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  • 1.
    Abtahi, Jahan
    et al.
    Linköping Univ, Dept Oral & Maxillofacial Surg, Linköping, Sweden.;Linköping Univ, Dept Biomed & Clin Sci, Linköping, Sweden.;Linköping Univ, Ctr Med Image Sci & Visualizat CMIV, Linköping, Sweden..
    Klintström, Benjamin
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Medicinsk avbildning.
    Klintström, Eva
    Linköping Univ, Ctr Med Image Sci & Visualizat CMIV, Linköping, Sweden.;Linköping Univ, Dept Radiol, Linköping, Sweden.;Linköping Univ, Dept Hlth Med & Caring Sci, Linköping, Sweden..
    Ibandronate Reduces the Surface Bone Resorption of Mandibular Bone Grafts: A Randomized Trial With Internal Controls2021Inngår i: JBMR Plus, ISSN 2473-4039, Vol. 5, nr 3, artikkel-id e10468Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Autologous bone grafts are considered the gold standard for reconstruction of the edentulous alveolar ridges. However, this procedure is associated with unpredictable bone loss caused by physiological bone resorption. Bisphosphonates are antiresorptive drugs that act specifically on osteoclasts, thereby maintaining bone density, volume, and strength. It was hypothesized that the resorption of bone grafts treated with an ibandronate solution would be less advanced than bone grafts treated with saline. Ten patients who underwent bilateral sagittal split osteotomy were included in a randomized double-blind trial with internal controls. Each patient received a bone graft treated with a solution of ibandronate on one side and a graft treated with saline (controls) contralaterally. Radiographs for the measurement of bone volume were obtained at 2 weeks and at 6 months after surgery. The primary endpoint was the difference in the change of bone volume between the control and the ibandronate bone grafts 6 months after surgery. All of the bone grafts healed without complications. One patient was excluded because of reoperation. In eight of the nine patients, the ibandronate bone grafts showed an increase in bone volume compared with baseline, with an average gain of 126 mm(3) (40% more than baseline) with a range of +27 to +218 mm(3). Only one ibandronate-treated graft had a decrease in bone volume (8%). In the controls, an average bone volume loss of -146 mm(3) (58% of baseline) with a range of -29 to -301 mm(3) was seen. In the maxillofacial field, the reconstructions of atrophic alveolar ridges, especially in the esthetical zones, are challenging. These results show that bone grafts locally treated with ibandronate solution increases the remaining bone volume. This might lead to new possibilities for the maxillofacial surgeons in the preservation of bone graft volumes and for dental implant installations.

  • 2.
    Basak, Togar
    et al.
    Univ Bayburt, Vocat Sch Hlth Serv, Dept Med Serv & Tech, Bayburt, Turkey..
    Hasan, Turkez
    Univ Ataturk, Sch Med, Dept Med Biol, Erzurum, Turkey..
    Feray, Bakan
    Univ Sabanci, Nanotechnol Res & Applicat Ctr, Istanbul, Turkey..
    Enes, Arslan Mehmet
    Univ Erzurum Tech, Fac Sci, Dept Mol Biol & Genet, Erzurum, Turkey..
    Abdulgani, Tatar
    Univ Ataturk, Sch Med, Dept Med Genet, Erzurum, Turkey..
    Ivana, Cacciatore
    Univ Gabriele dAnnunzio, Dept Pharm, Chieti Pescara, Italy..
    Ahmet, Hacimuftuoglu
    Univ Ataturk, Sch Med, Dept Med Pharmacol, Erzurum, Turkey..
    Kenan, Cadirci
    Univ Hlth Sci, Erzurum Reg Training & Res Hosp, Dept Internal Med, Erzurum, Turkey..
    Antonio, Stefano Di
    Univ Gabriele dAnnunzio, Dept Pharm, Chieti Pescara, Italy..
    Mardinoglu, Adil
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Systembiologi. Kings Coll London, Fac Dent Oral & Craniofacial Sci, Ctr Host Microbiome Interact, London, England..
    Synthesis and in Vitro Toxicity Assessment of Different Nano-Calcium Phosphate Nanoparticles2022Inngår i: Brazilian archives of biology and technology, ISSN 1516-8913, E-ISSN 1678-4324, Vol. 65, artikkel-id e22200784Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanoscale biomaterials are commonly used in a wide range of biomedical applications such as bone graft substitutes, gene delivery systems, and biologically active agents. On the other hand, the cytotoxic potential of these particles hasn't yet been studied comprehensively to understand whether or not they exert any negative impact on the cellular structures. Here, we undertook the synthesis of beta-tricalcium phosphate (beta-TCP) and biphasic tricalcium phosphate (BCP) nanoparticles (NPs) and determine their concentration-dependent toxic effects in human fetal osteoblastic (hFOB 1.19) cell line. Firstly, BCP and beta-TCP were synthesized using a water-based precipitation technique and characterized by X-Ray Diffraction (XRD), Raman Spectroscopy, and Transmission Electron Microscopy (TEM). The cytological effects of beta-TCP and BCP at different concentrations (0-640 ppm) were evaluated by using 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. The total oxidative status (TOS) parameter was used for investigating oxidative stress potentials of the NPs. In addition, the study assessed the DNA damage product 8-hydroxy-2'-deoxyguanosine (8-Oxo-dG) level in hFOB 1.19 cell cultures. The results indicated that the beta-TCP (above 320 ppm) and BCP (above 80 ppm) NPs exhibited cytotoxicity effects on high concentrations. It was also observed that the oxidative stress increased relatively as the concentrations of NPs increased, aligning with the cytotoxicity results. However, the NPs concentrations of 160 ppm and above increased the level of 8-OH-dG. Consequently, there is a need for more systematic in vivo and in vitro approaches to the toxic effects of both nanoparticles.

  • 3.
    Baza, Rabi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Teknisk vårdvetenskap.
    Evaluating Artificial Intelligence in Dental Radiography2024Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The integration of Artificial Intelligence (AI) in dental radiography not only presents an opportunity but also holds immense potential to enhance diagnostic accuracy and efficiency. This study addresses the exciting challenge of leveraging AI, specifically a generative pre-trained transformer model, to interpret dental panoramic X-rays, a task traditionally reliant on human expertise. The central purpose of the study is to evaluate the diagnostic capabilities of this AI model compared to professional dental evaluations, focusing on its accuracy and consistency, thereby paving the way for a promising future in dental diagnostics.

    The research involved a sample of 35 dental panoramic X-rays obtained from Flexident AB, anonymized and annotated by a panel of dental professionals. The study was conducted in two stages: Stage One tested the AI model in three different methods: 1- without any annotations, 2- with numbered teeth, and 3- with colored circles highlighting areas of interest. Stage Two involved training a specialized GPT model with domain-specific knowledge.

    Key findings indicate that the AI model, when provided with detailed visual annotations, achieved diagnostic accuracy comparable to that of dental professionals, as statistical analysis showed no significant differences between the golden standard (dentist group) and the visually annotated group (P>0.05). However, the model struggled with unannotated images, highlighting the importance of structured input. The research underscores the potential of language-based AI in medical imaging while emphasizing the need for detailed input to optimize performance. This study is pioneering in applying a generative pre-trained transformer model for dental diagnostics, opening new avenues for AI integration in healthcare.

    Fulltekst (pdf)
    fulltext
  • 4.
    Bergenstråhle, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Thormann, Esben
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Nordgren, Niklas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Force Pulling of Single Cellulose Chains at the Crystalline Cellulose-Liquid Interface: A Molecular Dynamics Study2009Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, nr 8, s. 4635-4642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pulling single cellulose molecules from a crystalline cellulose surface has been modeled by molecular dynamics (MD) simulations of the experimental procedure used in atomic force microscopy (AFM). Specifically, the aim of the study was to investigate cellulose interactions at desorption. Simulations were performed in both water and the organic solvent cyclohexane. Moreover, the effects of initial octamer conformation and orientation with respect to the surface chains were studied. A strong effect from the solvent was observed. In cyclohexane, normal forces of 200-500 pN and energies of 43.5 +/- 6.0 kJ/mol glucose unit were required to pull off the octamer. The normal forces in water were substantially lower, around 58 pN, and the energies were 18.2 +/- 3.6 kJ/mol glucose unit. In addition, the lateral components of the pull-off force were shown to provide information on initial conformation and orientation. Hydrogen bonds between the octamer and surface were analyzed and found to be an important factor in the pull-off behavior. Altogether, it was shown that MD provides detailed information on the desorption processes that may be useful for the interpretation of AFM experiments.

  • 5.
    Colding-Rasmussen, Thomas
    et al.
    Department of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Allé 30, Hvidovre, 2650, Denmark.
    Schwarzenberg, Peter
    AO Research Institute Davos, Clavadelerstrasse 8, Davos, 7270, Switzerland.
    Horstmann, Peter Frederik
    Department of Orthopedic Surgery, Gentofte Hospital, Gentofte Hospitalsvej 1, Hellerup, 2900, Denmark.
    Ottesen, Casper Bent Smedegaard
    Department of Orthopedic Surgery, Copenhagen University Hospital, Blegdamsvej 9, Copenhagen, Rigshospitalet, 2100, Denmark.
    San Jacinto García, Jorge
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Hutchinson, Daniel John
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Petersen, Michael Mørk
    epartment of Orthopedic Surgery, Copenhagen University Hospital, Blegdamsvej 9, Copenhagen, Rigshospitalet, 2100, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark.
    Varga, Peter
    AO Research Institute Davos, Clavadelerstrasse 8, Davos, 7270, Switzerland.
    Tierp-Wong, Christian Nai En
    Department of Orthopedic Surgery, Hvidovre University Hospital, Kettegaard Allé 30, Hvidovre, 2650, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen, 2200, Denmark.
    Biomechanical Variability and Usability of a Novel Customizable Fracture Fixation Technique2023Inngår i: Bioengineering, E-ISSN 2306-5354, Vol. 10, nr 10, artikkel-id 1146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel in situ customizable osteosynthesis technique, Bonevolent™ AdhFix, demonstrates promising biomechanical properties under the expertise of a single trained operator. This study assesses inter- and intra-surgeon biomechanical variability and usability of the AdhFix osteosynthesis platform. Six surgeons conducted ten osteosyntheses on a synthetic bone fracture model after reviewing an instruction manual and completing one supervised osteosynthesis. Samples underwent 4-point bending tests at a quasi-static loading rate, and the maximum bending moment (BM), bending stiffness (BS), and AdhFix cross-sectional area (CSA: mm²) were evaluated. All constructs exhibited a consistent appearance and were suitable for biomechanical testing. The mean BM was 2.64 ± 0.57 Nm, and the mean BS was 4.35 ± 0.44 Nm/mm. Statistically significant differences were observed among the six surgeons in BM (p < 0.001) and BS (p = 0.004). Throughout ten trials, only one surgeon demonstrated a significant improvement in BM (p < 0.025), and another showed a significant improvement in BS (p < 0.01). A larger CSA corresponded to a statistically significantly higher value for BM (p < 0.001) but not for BS (p = 0.594). In conclusion, this study found consistent biomechanical stability both across and within the surgeons included, suggesting that the AdhFix osteosynthesis platform can be learned and applied with minimal training and, therefore, might be a clinically viable fracture fixation technique. The variability in BM and BS observed is not expected to have a clinical impact, but future clinical studies are warranted.

  • 6. Cornelio, Roberto Belloti
    et al.
    Wikant, Aksel
    Mjosund, Hanne
    Kopperud, Hilde Molvig
    Haasum, Johan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ortengren, Ulf Thore
    The influence of bis-EMA vs bis GMA on the degree of conversion and water susceptibility of experimental composite materials2014Inngår i: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 72, nr 6, s. 440-447Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective. The aim of this work was to assess the influence of the bis-EMA content on the degree of conversion (DC) and its effect on the water sorption and solubility. Materials and methods. In a polytetrafluorethylene (PTFE) mould, 30 samples (O = 5 mm, height = 2 mm) of four experimental dental composite resins were cured for 10 s, 20 s and 40 s. The DC was analysed by Fourier Transform (FT)-Raman spectroscopy. To analyse sorption and solubility, six samples (O = 15 mm and thickness = 1 mm) of each composite (n = 72) were stored in water at 37 degrees C for different storage periods: 24 h, 7 days and 30 days. Results. When cured for 20 or 40 s the DC increased with the increasing content of bis-EMA. However, the presence of 15 wt% of bis-GMA did not affect the DC, except when cured with 10 s irradiation time. This study also found a correlation between the content of bis-EMA and the reduced values for sorption and solubility, for all storage times used, when the materials were cured with 20 s. Conclusions. The DC of mixtures with higher content of bis-EMA is affected by the presence of bis-GMA at lower energy density delivered from the curing device, suggesting that the restrictions caused by the presence of hydrogen bonds is dependent of the irradiation time used.

  • 7. Daub, Jennifer
    et al.
    Gardner, Paul P.
    Tate, John
    Ramsköld, Daniel
    KTH.
    Manske, Magnus
    Scott, William G.
    Weinberg, Zasha
    Griffiths-Jones, Sam
    Bateman, Alex
    The RNA WikiProject: Community annotation of RNA families2008Inngår i: RNA: A publication of the RNA Society, ISSN 1355-8382, E-ISSN 1469-9001, Vol. 14, nr 12, s. 2462-2464Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The online encyclopedia Wikipedia has become one of the most important online references in the world and has a substantial and growing scientific content. A search of Google with many RNA-related keywords identifies a Wikipedia article as the top hit. We believe that the RNA community has an important and timely opportunity to maximize the content and quality of RNA information in Wikipedia. To this end, we have formed the RNA WikiProject (http://en.wikipedia.org/wiki/Wikipedia: WikiProject_RNA) as part of the larger Molecular and Cellular Biology WikiProject. We have created over 600 new Wikipedia articles describing families of noncoding RNAs based on the Rfam database, and invite the community to update, edit, and correct these articles. The Rfam database now redistributes this Wikipedia content as the primary textual annotation of its RNA families. Users can, therefore, for the first time, directly edit the content of one of the major RNA databases. We believe that this Wikipedia/Rfam link acts as a functioning model for incorporating community annotation into molecular biology databases.

  • 8.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    Inverse agreement algorithms with application to swarm dispersion for multiple nonholonomic agents2008Inngår i: 2008 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, 2008, s. 1973-1978Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We propose an inverse agreement control strategy for multiple nonholonomic agents that forces the team members to disperse in the workspace in a distributed manner. Both the cases of an unbounded and a circular bounded workspace are considered. In the first case, we show that the closed loop system reaches a configuration in which the minimum distance between any pair of agents is larger than a specific lower bound. It is proved that this lower bound coincides with the agents' sensing radius. In the case of a bounded workspace, the control law is modified to force the agents to remain within the workspace boundary throughout the closed loop system evolution. Moreover the proposed control guarantees collision avoidance between the team members. The results are supported through relevant computer simulations.

  • 9.
    Ferrannini, G.
    et al.
    Karolinska Inst, Med, Stockholm, Sweden..
    Norhammar, A.
    Karolinska Inst, Med, Stockholm, Sweden..
    Almosawi, M.
    Karolinska Inst, Med, Stockholm, Sweden..
    Kjellstrom, B.
    Karolinska Inst, Med, Stockholm, Sweden..
    Buhlin, K.
    Karolinska Inst, Dent Med, Stockholm, Sweden..
    De Faire, U.
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Gustafsson, A.
    Karolinska Inst, Dent Med, Stockholm, Sweden..
    Nygren, L. A.
    Clin Sci Danderyds Hosp, Karolinska Inst, Stockholm, Sweden..
    Näsman, Per
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Lindahl, B.
    Uppsala Univ, Med Sci, Uppsala, Sweden..
    Naslund, U.
    Umeå Univ, Dept Publ Hlth & Clin Med, Umeå, Sweden..
    Svenungsson, E.
    Karolinska Inst, Med, Stockholm, Sweden..
    Klinge, B.
    Karolinska Inst, Dent Med, Stockholm, Sweden..
    Ryden, L.
    Karolinska Inst, Med, Stockholm, Sweden..
    Periodontitis and cardiovascular outcome - a prospective follow-up of the PAROKRANK cohort2021Inngår i: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 42, s. 1120-1120Artikkel i tidsskrift (Annet vitenskapelig)
  • 10.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Multifunctional nanomaterials for diagnostic and therapeutic applications2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In the past few years, the use of nanostructured materials in medical applications hasdramatically increased, both in the research phase and for clinical purposes, due to thepeculiar properties and the ability of such materials to interact at a similar scale withbiological entities. In this thesis, we developed tailored magnetic multifunctionalnanoparticles for diagnostic and therapeutic applications, such as detection ofbiomolecules, simultaneous enhanced magnetic resonance imaging (MRI), fluorescentvisualization and controlled drug release.For sensitive and selective detection of specific biomolecules, thermally blocked ironoxide nanoparticles with tailored magnetic properties were developed. The formation ofsuch nanoparticles has been studied both in terms of size and magnetic behavior in liquidsuspension or in polymer matrixes. These particles with narrow size distribution (averagediameter of 19 nm) were surface functionalized by antigen molecules and were used forthe detection of Brucella antibodies in biological samples. The binding of biomoleculesresults in an increase in the particle’s hydrodynamic diameter, affecting the relaxationbehavior that was monitored by magnetic measurements. This sensing system is a fastand sensitive biosensor with very low detection limits (0.05 μg/mL).Superparamagnetic iron oxide nanoparticles (SPION) have been synthesized withaverage diameter of 10-12 nm, narrow size distribution, high crystallinity and superiormagnetic properties as liquid suspensions or embedded in a bulk transparent magneticnanocomposite. These nanoparticles were synthesized in organic solvents and, after phasetransfer with Pluronic F127 amphiphilic copolymer, show excellent relaxivity properties(high r2/r1 ratio) and great contrast enhancement in T2 weighted MRI, confirmed by invivostudies of rat inner ear.SPION have been used as a component for different multifunctional nanostructures. Thefirst system based on poly (L,L lactide)-methoxy polyethylene glycol (PLLA-mPEG)copolymer has been prepared by an emulsion/evaporation process that lead to polymericnanoparticles containing several imaging agents, such as SPION, quantum dots (QDs)and gold nanorods as well as indomethacin (IMC) as therapeutic payload. With a similarprocedure, but using poly (lactide-co-glycolide) (PLGA-PEG-NH2) copolymer, a secondtype of multifunctional nanoparticles has been obtained. Their size can be tailored from70 to 150 nm varying synthesis parameters, such as the surfactant concentration or waterto oil ratio. Both these polymer-based multifunctional nanoparticles can be visualized byfluorescence microscopy (QDs photoemission) and MRI (SPION magnetization) and theycan be used for photothermal therapy (gold nanorods) and drug delivery. The last systemconsists of SPION nanoparticles coated with PLLA directly on the surface by an in-situpolymerization process. A hydrophobic drug was loaded before the phase transfer withPluronic F127 and these nanoparticles show simultaneous MRI T2 contrast enhancementas well as high drug loading and sustained delivery.Controlling the drug release rate is also a critical parameter for tailored therapeutictreatments, and for this reason we developed a novel drug delivery system based on theintegration of SPION and Pluronic F127 gels. IMC was loaded in the ferrogel (with atailored gelation temperature) and its release rate was triggered by applying an externalmagnetic field owing to the SPION magnetic properties.

    Fulltekst (pdf)
    FULLTEXT01
  • 11.
    Fornara, Andrea
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Chiavarino, Annalisa
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    PLGA-PEG multifunctional nanoparticles for simultaneous drug delivery and visualizationInngår i: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896XArtikkel i tidsskrift (Annet vitenskapelig)
  • 12. Gray-Mitsumune, Madoka
    et al.
    Mellerowicz, Ewa J.
    Abe, Hisashi
    Schrader, Jarmo
    Winzell, Anders
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Sterky, Fredrik
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Blomqvist, Kristina
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    McQueen-Mason, Simon
    Teeri, Tuula T.
    KTH, Tidigare Institutioner (före 2005), Bioteknologi.
    Sundberg, Björn
    Expansins abundant in secondary xylem belong to subgroup a of the alpha-expansin gene family (1 w )2004Inngår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 135, nr 3, s. 1552-1564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Differentiation of xylem cells in dicotyledonous plants involves expansion of the radial primary cell walls and intrusive tip growth of cambial derivative cells prior to the deposition of a thick secondary wall essential for xylem function. Expansins are cell wall-residing proteins that have an ability to plasticize the cellulose-hemicellulose network of primary walls. We found expansin activity in proteins extracted from the cambial region of mature stems in a model tree species hybrid aspen (Populus tremula X Populus tremuloides Michx). We identified three a-expansin genes (PttEXP1, PttEXP2, and PttEXP8) and one beta-expansin gene (PttEXPB1) in a cambial region expressed sequence tag library, among which PttEXP1 was most abundantly represented. Northern-blot analyses in aspen vegetative organs and tissues showed that PttEXP1 was specifically expressed in mature stems exhibiting secondary growth, where it was present in the cambium and in the radial expansion zone. By contrast, PttEXP2 was mostly expressed in developing leaves. In situ reverse transcription-PCR provided evidence for accumulation of mRNA of PttEXP1 along with ribosomal rRNA at the tips of intrusively growing xylem fibers, suggesting that PttEXP1 protein has a role in intrusive tip growth. An examination of tension wood and leaf cDNA libraries identified another expansin, PttEXP5, very similar to PttEXP1, as the major expansin in developing tension wood, while PttEXP3 was the major expansin expressed in developing leaves. Comparative analysis of expansins expressed in woody stems in aspen, Arabidopsis, and pine showed that the most abundantly expressed expansins share sequence similarities, belonging to the subfamily A of alpha-expansins and having two conserved motifs at the beginning and end of the mature protein, RIPVG and KNFRV, respectively. This conservation suggests that these genes may share a specialized, not yet identified function.

  • 13.
    Hassel, Ivon
    et al.
    Laboratory of Structural Function, Research Institute for Sustainable Humanosphere, Kyoto University.
    Berard, Pierre
    Laboratory of Sustainable Materials, Research Institute for Sustainable Humanosphere, Kyoto University.
    Modén, Carl S.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    The single cube apparatus for shear testing: Full-field strain data and finite element analysis of wood in transverse shear2009Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 69, nr 7-8, s. 877-882Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The design and analysis of wood structures require accurate data for shear properties, where transverse shear in particular has been neglected in the past. The single cube apparatus (SCA) was applied to transverse shear of Norway spruce (Picea Abies), due to the importance of this species in wood structures, such as glulam, and also its allegedly low value of GRT . Full-field strain data and FEA were used to analyze the potential of the method. The presence of a large central region of homogeneous and close to pure shear strain was confirmed. The SCA method is therefore a strong candidate for improved shear test procedures in wood and other materials, where porosity (gripping problems), heterogeneity on mm-scale and polar orthotropy (annual ring curvature) may cause particular difficulties. In contrast to many other shear test studies, the accuracy of the present GRT data is supported by documented large and homogeneous specimen stress- and strain-fields in almost pure shear, direct measurements of strain field, and careful stress analysis based on FEA.

  • 14.
    Hedberg, Yolanda S.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Qian, Bin
    Shen, Zhijian
    Virtanen, Sannakaisa
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    In vitro biocompatibility of CoCrMo dental alloys fabricated by selective laser melting2014Inngår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 30, nr 5, s. 525-534Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective. Selective laser melting (SLM) is increasingly used for the fabrication of customized dental components made of metal alloys such as CoCrMo. The main aim of the present study is to elucidate the influence of the non-equilibrium microstructure obtained by SLM on corrosion susceptibility and extent of metal release (measure of biocompatibility). Methods. A multi-analytical approach has been employed by combining microscopic and bulk compositional tools with electrochemical techniques and chemical analyses of metals in biologically relevant fluids for three differently SLM fabricated CoCrMo alloys and one cast CoCrMo alloy used for comparison. Results. Rapid cooling and strong temperature gradients during laser melting resulted in the formation of a fine cellular structure with cell boundaries enriched in Mo (Co depleted), and suppression of carbide precipitation and formation of a martensitic epsilon (hcp) phase at the surface. These features were shown to decrease the corrosion and metal release susceptibility of the SLM alloys compared with the cast alloy. Unique textures formed in the pattern of the melting pools of the three different laser melted CoCrMo alloys predominantly explain observed small, though significant, differences. The susceptibility for corrosion and metal release increased with an increased number (area) of laser melt pool boundaries. Significance. This study shows that integrative and interdisciplinary studies of microstructural characteristics, corrosion, and metal release are essential to assess and consider during the design and fabrication of CoCrMo dental components of optimal biocompatibility. The reason is that the extent of metal release from CoCrMo is dependent on fabrication procedures.

  • 15.
    Holzapfel, Gerhard A.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Biomekanik.
    Sommer, Gerhard
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Biomekanik.
    Gasser, Christian T.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Biomekanik.
    Regitnig, P
    Determination of layer-specific mechanical properties of human coronary arteries with nonatherosclerotic intimal thickening and related constitutive modeling2005Inngår i: American Journal of Physiology. Heart and Circulatory Physiology, ISSN 0363-6135, E-ISSN 1522-1539, Vol. 289, nr 5, s. H2048-H2058Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    At autopsy, 13 nonstenotic human left anterior descending coronary arteries [71.5 +/- 7.3 ( mean +/- SD) yr old] were harvested, and related anamnesis was documented. Preconditioned prepared strips (n = 78) of segments from the midregion of the left anterior descending coronary artery from the individual layers in axial and circumferential directions were subjected to cyclic quasi-static uniaxial tension tests, and ultimate tensile stresses and stretches were documented. The ratio of outer diameter to total wall thickness was 0.189 +/- 0.014; ratios of adventitia, media, and intima thickness to total wall thickness were 0.4 +/- 0.03, 0.36 +/- 0.03, and 0.27 +/- 0.02, respectively; axial in situ stretch of 1.044 +/- 0.06 decreased with age. Stress-stretch responses for the individual tissues showed pronounced mechanical heterogeneity. The intima is the stiffest layer over the whole deformation domain, whereas the media in the longitudinal direction is the softest. All specimens exhibited small hysteresis and anisotropic and strong nonlinear behavior in both loading directions. The media and intima showed similar ultimate tensile stresses, which are on average three times smaller than ultimate tensile stresses in the adventitia (1,430 +/- 604 kPa circumferential and 1,300 +/- 692 kPa longitudinal). The ultimate tensile stretches are similar for all tissue layers. A recently proposed constitutive model was extended and used to represent the deformation behavior for each tissue type over the entire loading range. The study showed the need to model nonstenotic human coronary arteries with nonatherosclerotic intimal thickening as a composite structure composed of three solid mechanically relevant layers with different mechanical properties. The intima showed significant thickness, load-bearing capacity, and mechanical strength compared with the media and adventitia.

  • 16. Janiszewska-Olszowska, Joanna
    et al.
    Szatkiewicz, Tomasz
    Tomkowski, Robert
    Department of Fine Mechanics, Koszalin University of Technology, Koszalin, Poland.
    Tandecka, Katarzyna
    Grocholewicz, Katarzyna
    Effect of orthodontic debonding and adhesive removal on the enamel - current knowledge and future perspectives - a systematic review.2014Inngår i: Medical Science Monitor, ISSN 1234-1010, E-ISSN 1643-3750, Vol. 20, s. 1991-2001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    After orthodontic treatment, brackets are debonded and residual adhesive is removed, causing iatrogenic enamel damage. The aim of this study was to review the methods of orthodontic adhesive removal, find clear evidence, and provide a rationale for this procedure. A literature search was performed in PubMed, Dentistry and Oral Sciences, Scopus, Cochrane, Google, and Google Scholar using keywords: orthodontic adhesive removal, orthodontic debonding, orthodontic clean-up. Studies concerning human enamel roughness or loss from debonding and adhesive removal were considered. Forty-four full-text articles were analyzed and 3 were rejected after detailed reading; finally 41 papers were included. Fifteen qualitative studies, 13 studies based on indices of enamel surface, and 13 quantitative studies were found. No meta-analysis could be performed due to a lack of homogenous quantitative evidence. The most popular tools were tungsten carbide burs, which were faster and more effective than Sof-Lex discs, ultrasonic tools, hand instruments, rubbers, or composite burs. They remove a substantial layer of enamel and roughen its surface, but are less destructive than Arkansas stones, green stones, diamond burs, steel burs, and lasers. Multi-step Sof-Lex discs and pumice slurry are the most predictable enamel polishing tools. Arkansas stones, green stones, diamond burs, steel burs, and lasers should not be used for adhesive removal. The use of tungsten carbide bur requires multistep polishing. Further efforts should be made to find tools and methods for complete removal of adhesive remnants, minimizing enamel loss and achieving a smooth surface.

  • 17. Janiszewska-Olszowska, Joanna
    et al.
    Tomkowski, Robert
    Faculty of Mechanical Engineering, Koszalin University of Technology.
    Tandecka, Katarzyna
    Stepien, Piotr
    Szatkiewicz, Tomasz
    Sporniak-Tutak, Katarzyna
    Grocholewicz, Katarzyna
    Effect of orthodontic debonding and residual adhesive removal on 3D enamel microroughness.2016Inngår i: PeerJ, E-ISSN 2167-8359, Vol. 4, artikkel-id e2558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Termination of fixed orthodontic treatment is associated with bracket debonding and residual adhesive removal. These procedures increase enamel roughness to a degree that should depend on the tool used. Enamel roughening may be associated with bacterial retention and staining. However, a very limited data exists on the alteration of 3D enamel roughness resulting from the use of different tools for orthodontic clean-up.

    AIMS: 1. To perform a precise assessment of 3D enamel surface roughness resulting from residual adhesive removal following orthodontic debonding molar tubes. 2. To compare enamel surfaces resulting from the use of tungsten carbide bur, a one-step polisher and finisher and Adhesive Residue Remover.

    MATERIAL AND METHODS: Buccal surfaces of forty-five extracted human third molars were analysed using a confocal laser microscope at the magnification of 1080× and 3D roughness parameters were calculated. After 20 s etching, molar tubes were bonded, the teeth were stored in 0.9% saline solution for 24 hours and debonded. Residual adhesive was removed using in fifteen specimen each: a twelve-fluted tungsten carbide bur, a one-step finisher and polisher and Adhesive Residue Remover. Then, surface roughness analysis was repeated. Data normality was assessed using Shapiro-Wilk test. Analysis of variance (ANOVA) was used to compare between variables of normal distribution and for the latter-Kruskal-Wallis test.

    RESULTS: Sa (arithmetical mean height) was significantly different between the groups (p = 0, 01326); the smoothest and most repeatable surfaces were achieved using Adhesive Residue Remover. Similarly, Sq (root mean square height of the scale-limited surface) had the lowest and most homogenous values for Adhesive Residue Remover (p = 0, 01108). Sz (maximum height of the scale-limited surface) was statistically different between the groups (p = 0, 0327), however no statistically significant differences were found concerning Ssk (skewness of the scale-limited surface).

    DISCUSSION: Confocal laser microscopy allowed 3D surface analysis of enamel surface, avoiding the limitations of contact profilometry. Tungsten carbide burs are the most popular adhesive removing tools, however, the results of the present study indicate, that a one step polisher and finisher as well as Adhesive Residue Remover are less detrimental to the enamel. This is in agreement with a recent study based on direct 3D scanning enamel surface. It proved, that a one-step finisher and polisher as well as Adhesive Residue Remover are characterized by a similar effectiveness in removing residual remnants as tungsten carbide bur, but they remove significantly less enamel.

    CONCLUSION: Orthodontic debonding and removal of adhesive remnants increases enamel roughness. The smoothest surfaces were achieved using Adhesive Residue Remover, and the roughest using tungsten carbide bur.

  • 18.
    Liu, Hua
    et al.
    Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, P. R. China, 197 Ruijin 2nd Road; Department of Orthopaedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopaedics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, P. R. China, 197 Ruijin 2nd Road.
    Fan, Yanmiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Zhong, Jie
    Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, P. R. China, 197 Ruijin 2nd Road.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Cai, Zhengwei
    Department of Orthopaedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopaedics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, P. R. China, 197 Ruijin 2nd Road.
    Wang, Zhengting
    Department of Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai 200025, P. R. China, 197 Ruijin 2nd Road.
    Advance in oral delivery of living material2023Inngår i: Biomedical Technology, E-ISSN 2949-723X, Vol. 3, s. 26-39Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Nowadays, living therapeutics is a promising candidate among various therapies, and oral administration of living therapeutics characterized by universality and safety avail to make the transition from bench to bedside. However, precise delivery and continuous maintenance of cell viability and activity to acquire stable and ideal therapeutic efficacy remain challenging. Living material is the smart integration of the flexibly programmable functionality of biomaterial and the autonomous environmental responsiveness of living elements, heralding a new era of biotherapeutics in addressing human health concerns. Here, our review aims at presenting an overview of the status of the oral delivery of living material from a biological, technical, and practical perspective, describing the clinical significance and potential, the current technological development and dilemma, as well as the prospect.

  • 19.
    Liu, Yanling
    KTH, Skolan för bioteknologi (BIO).
    Electric DNA arrays for determination of pathogenic Bacillus cereus2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Silicon-based electric chip arrays were developed for characterization of Bacillus

    cereus with respect to the capacity to produce toxins involved in food poisoning and foodborne infections. Bacteria of the B. cereus group contain different sets of four toxins encoded by eight genes. The purpose of this work was to develop a fast method for determination of the presence of these genes in colonies from primary enrichment cultures. The specific DNA detection was based on immobilization of DNA capture probes, which hybridize to specific sites on the target genes. Biotin-labeled detection probes were designed to hybridize with the target DNA adjacent to the capture probes. An extravidin - alkaline phosphatase complex was subsequently bound to the hybridized detection probes. Finally, p-aminophenyl phosphate was added as substrate for the enzyme, and the product p-aminophenol was brought in contact with the interdigitated gold electrode on the silicon chips surface. The p-aminophenol was oxidized at the anode to quinoneimine, which was then reduced back to paminophenol at the cathode. This redox recycling generates a current that was used as the DNA-chip response to the target DNA. Two versions of the assay were used. In the first version the capture probes were immobilized on magnetic beads and all

    chemical reactions until and including the enzymatic reaction took place in an

    eppendorf tube while the redox recycling was used to measure the amount of paminophenol produced after transfer from the tube to the silicon chip surface. In the second version a silicon chip array was used with 16 parallel electrode positions, each activated by immobilization of one type of capture probes on the gold electrodes. With this system all chemical reactions took place at the chip surface. The kinetics of cell disruption and DNA fragmentation from B. cereus by ultrasonication was determined. Maximum cell disruption was achieved within 5 min and the chip response increased in proportion to the ultrasonic time. Further ultrasonication up to 10 min resulted in further increasing current although no further cell disruption was observed. If the sonication time was extended above 10 min the signal declined. Based on analysis of the DNA size distribution by early end-point PCR and gel electrophoresis, it is suggested that the first 5 min ultrasonication increased the signal by increasing the release of target DNA molecules. Thereafter the signal was increased by fragmentation of target DNA which increases the diffusion rate and also the accessibility of the hybridization site. Finally, the DNA fragment sizes approached that of the hybridization site (51-bp) which may reduce the signal because of cleavage of the target DNA in the hybridization region. These studies were performed with the bead-based hybridization assay. The assay was highly specific to the target gene (hblC) of both B. cereus and B. thuringiensis with no response from negative control

    cells of B. subtilis. The 16 positions of the silicon chip array were activated by

    immobilization of all known toxin-coding genes of B. cereus and also included both a positive control and a negative control electrode positions. When these chips were exposed to ultrasonicated B. cereus, the gold electrodes were fouled by some component in DNA cell lysates. To circumvent this, the released large DNA was first extracted and then ultrasonicated again, since the extract mainly contains large molecular weight DNA. This DNA extract was applied to characterize one “diarrheal” and one “emetic” strain of B. cereus with the DNA chip arrays. The results agreed with PCR control analysis which means that these electric DNA chip arrays can be used to characterize bacterial colonies with respect to the genes coding of all known toxins of B. cereus: haemolysin (hblA, hblC, hblD), non-haemolytic enterotoxin (nheA, nheB, nheC), cytotoxin K-2 (cytK-2), and cereulide (ces). The chip assay required about 30 min after application of DNA samples. Due to the generic properties of the chips, this technique should also be applicable for characterization of the pathogenicity potential of many other organisms. Keywords: Bacillus cereus, haemolysin, non-haemolytic enterotoxin, cytotoxin K-2, cereulide, toxin-coding genes, bacterial colony, electric DNA chip, ultrasonication, DNA fragmentation.

    Fulltekst (pdf)
    FULLTEXT01
  • 20. Lombard, Vincent
    et al.
    Bernard, Thomas
    Rancurel, Corinne
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Coutinho, Pedro M.
    Henrissat, Bernard
    A hierarchical classification of polysaccharide lyases for glycogenomics2010Inngår i: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 432, s. 437-444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbohydrate-active enzymes face huge substrate diversity in a highly selective manner using only a limited number of available folds. They are therefore subjected to multiple divergent and convergent evolutionary events. This and their frequent modularity render their functional annotation in genomes difficult in a number of cases. In the present paper, a classification of polysaccharide lyases (the enzymes that cleave polysaccharides using an elimination instead of a hydrolytic mechanism) is shown thoroughly for the first time. Based on the analysis of a large panel of experimentally characterized polysaccharide lyases, we examined the correlation of various enzyme properties with the three levels of the classification: fold, family and subfamily. The resulting hierarchical classification, which should help annotate relevant genes in genomic efforts, is available and constantly updated at the Carbohydrate-Active Enzymes Database (http://www.cazy.org).

  • 21. Malmqvist, S.
    et al.
    Liljeborg, Anders V. G.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Qadri, T.
    Johannsen, G.
    Johannsen, A.
    Using 445 nm and 970 nm lasers on dental implants-an in vitro study on change in temperature and surface alterations2019Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 23, artikkel-id 3934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to evaluate the safety of using a 445 nm laser on dental implants by comparing it with a laser with 970 nm wavelength. Two models, a pig mandible and glass ionomer cement, were used to evaluate the temperature increase in dental implants during laser irradiation with both wavelengths. Temperature was measured every second at four different places on the dental implants. Different power settings, effects of water cooling, distance of the laser fibre to the dental implant and continuous comparison to a pulsed laser beam were tested. Surface alterations on titanium discs after laser irradiation for 4 min at 2.0 W, were analysed in a scanning electron microscope (SEM). The maximum temperature and time to reach each of the thresholds were comparable between the 445 nm and 970 nm lasers. Neither the 445 nm nor the 970 nm wavelength showed any signs of surface alterations on the titanium discs. Using a 445 nm laser on dental implants is as safe as using a 970 nm laser, in terms of temperature increase and surface alterations. Applying a generous amount of cooling water and irradiating in short intervals is important when using lasers on dental implants.

  • 22.
    Modén, Carl S.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Micromechanics of softwoods in the transverse plane: effects on cell and annual ring scales2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Transverse mechanical properties of wood are important in many practial applications and an interesting scientific subject. A very low transverse shear modulus has been identified in spruce, which causes large strain concentrations in wood structures. In this thesis, experimental characterization of local density variations as well as local strain fields are carried out using the SilviScan apparatus and digital speckle photography, respectively. This is combined with micromechanical modeling based on hexagonal wood cells in combination with finite element analysis. Problems addressed include the moduli in the transverse plane, including variations at the scale of individual annual rings. The relative importance of cell wall bending and stretching deformation mechanisms is analysed as a function of wood cell geometry, relative density and direction of loading (radial, tangential and shear). Transverse anisotropy is also analyzed, including its dependency of earlywood and latewood characteristics. The wood cell shape angle variation and density effects are sufficient to explain transverse anisotropy in softwoods (no ray effects), and the influence of earlywood/latewood ratio is explained. As a practical test method for shear modulus measurements, an off-axis compression test with full-field strain determination is proposed. The advantage is a simple fixture and large region of representative strain required for a heterogeneous material such as wood. As an alternative, the single cube apparatus (SCA) for shear tests is evaluated. The SCA is used to determine the shear strain distribution within the annual rings. Based on the density distribution of the shear test specimen and a micromechanics model, a finite element model is developed, and predictions are compared with the measured shear strains. The agreement between predicted and measured shear strains at the annual ring scale are remarkably good. It shows that the low GRT of spruce is due to the low earlywood density and the large cell wall bending deformation resulting from shear loading. Furthermore, it illustrates the need for improved understanding of annual ring scale effects. For example, fairly low transverse global loads will lead to lage local shear strains.

    Fulltekst (pdf)
    FULLTEXT01
  • 23.
    Modén, Carl S.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Biokompositer.
    A two-phase annual ring model of transverse anisotropy in softwoods2008Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 68, nr 14, s. 3020-3028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transverse anisotropy in softwoods is an important phenomenon of both scientific and industrial interest. Simple one-phase hexagonal honeycomb cell models for transverse moduli of softwoods are based on cell wall bending as the only deformation mechanism. In the present study, a two-phase annual ring model is developed and includes both cell wall bending and stretching as deformation mechanisms. The proportion of cell wall bending and stretching for different cases is analysed and the importance of stretching is confirmed. A two-phase annual ring model is presented based on fixed densities for earlywood and latewood. Such a model is motivated by the large difference in density between earlywood and latewood layers. Two-phase model predictions show much better agreement with experimental data than predictions from a one-phase model. Radial modulus is dominated by bending at low density and by stretching at high density. For tangential modulus, bending is more important at all densities.

  • 24. Mutafela, R. N.
    et al.
    Fei, Ye
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik.
    Jani, Y.
    Dutta, Joydeep
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Material- och nanofysik. Center of Nanotechnology, King Abdulaziz University, Jeddah, 21589, Saudi Arabia.
    Hogland, W.
    Sustainable extraction of hazardous metals from crystal glass waste using biodegradable chelating agents2022Inngår i: Journal of Material Cycles and Waste Management, ISSN 1438-4957, E-ISSN 1611-8227, Vol. 24, nr 2, s. 692-701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extraction of hazardous metals from dumped crystal glass waste was investigated for site decontamination and resource recovery. Mechanically activated glass waste was leached with biodegradable chelating agents of ethylenediamine-N,N′-disuccinic acid (EDDS) and nitrilotriacetic acid (NTA), where the concentration and reaction time were determined by using Box–Wilson experimental design. Hazardous metals of lead (Pb), arsenic (As), antimony (Sb) and cadmium (Cd) with concentrations higher than regulatory limits were extracted wherein the extraction yield was found to vary Pb > Sb > As > Cd. Extraction was influenced more by type and concentration of chelator rather than by reaction time. A maximum of 64% of Pb could be extracted by EDDS while 42% using NTA. It is found that increase of chelator concentrations from 0.05 M to 1 M did not show improved metal extraction and the extraction improved with reaction time until 13 h. This study provides sustainable alternative for treating hazardous glass waste by mechanical activation followed by extraction using biodegradable chelator, instead of acid leaching. Graphical abstract: [Figure not available: see fulltext.]. 

  • 25.
    Osinger, Barbara
    et al.
    Uppsala Univ, Dept Chem Angstrom, SE-75121 Uppsala, Sweden..
    Mao, Huahai
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermo Calc Software AB, Solna, Sweden..
    Fritze, Stefan
    Uppsala Univ, Dept Chem Angstrom, SE-75121 Uppsala, Sweden..
    Riekehr, Lars
    Uppsala Univ, Dept Chem Angstrom, SE-75121 Uppsala, Sweden.;Univ Antwerp, Dept Phys, Antwerp, Belgium..
    Jansson, Ulf
    Uppsala Univ, Dept Chem Angstrom, SE-75121 Uppsala, Sweden..
    Lewin, Erik
    Uppsala Univ, Dept Chem Angstrom, SE-75121 Uppsala, Sweden..
    Investigation of the phase formation in magnetron sputtered hard multicomponent (HfNbTiVZr)C coatings2022Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 221, artikkel-id 111002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicomponent carbides have gained interest especially for ultra-high temperature applications, due to their ceramic hardness, good oxidation resistance and enhanced strength. In this study the phase forma-tion, stability and mechanical properties of (HfNbTiVZr)C multicomponent carbide coatings were inves-tigated. Phase stability was predicted by the CALPHAD (CALculation of PHAse Diagrams) methods. This revealed that the multicomponent solid solution phase is only stable at elevated temperatures, namely above 2400 degrees C. At lower temperatures a phase mixture was predicted, with a particular tendency for V to segregate. Magnetron sputtered thin films deposited at 300 degrees C exhibited a single NaCl-type multicom-ponent carbide phase, which attributes to the kinetic stabilisation of simple structures during thin film growth. Films deposited at 700 degrees C, or exposed to UHV annealing at 1000 degrees C, however, revealed the decom-position of the single-phase multicomponent carbide by partial elemental segregation and formation of additional phases. Thus, confirming the CALPHAD predictions. These results underscore the importance of explicitly considering temperature when discussing the stability of multicomponent carbide materials, as well as the applicability of CALPHAD methods for predicting phase formation and driving forces in these materials. The latter being crucial for designing materials, such as carbides, that are used in appli-cations at elevated temperatures.

  • 26.
    Ouldyerou, Abdelhak
    et al.
    Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria.
    Mehboob, Hassan
    Department of Engineering Management, College of Engineering, Prince Sultan University, Riyadh, Saudi Arabia.
    Mehboob, Ali
    Advanced Digital & Additive Manufacturing Center, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
    Merdji, Ali
    Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria.
    Aminallah, Laid
    Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria.
    Mukdadi, Osama M.
    Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia, United States of America.
    Barsoum, Imad
    KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik. Advanced Digital & Additive Manufacturing Center, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
    Junaedi, Harri
    Department of Engineering Management, College of Engineering, Prince Sultan University, Riyadh, Saudi Arabia.
    Biomechanical performance of resin composite on dental tissue restoration: A finite element analysis2023Inngår i: PLOS ONE, E-ISSN 1932-6203, Vol. 18, nr 12 December, artikkel-id e0295582Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigates the biomechanical performance of various dental materials when filled in different cavity designs and their effects on surrounding dental tissues. Finite element models of three infected teeth with different cavity designs, Class I (occlusal), Class II mesial-occlusal (MO), and Class II mesio-occluso-distal (MOD) were constructed. These cavities were filled with amalgam, composites (Young’s moduli of 10, 14, 18, 22, and 26 GPa), and glass carbomer cement (GCC). An occlusal load of 600 N was distributed on the top surface of the teeth to carry out simulations. The findings revealed that von Mises stress was higher in GCC material, with cavity Class I (46.01 MPa in the enamel, 23.61 MPa in the dentin), and for cavity Class II MO von Mises stress was 43.64 MPa, 39.18 MPa in enamel and dentin respectively, while in case of cavity Class II MOD von Mises stress was 44.67 MPa in enamel, 27.5 in the dentin. The results showed that higher stresses were generated in the non-restored tooth compared to the restored one, and increasing Young’s modulus of restorative composite material decreases stresses in enamel and dentin. The use of composite material showed excellent performance which can be a good viable option for restorative material compared to other restorative materials.

  • 27.
    Palmberg, Robin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Centra, Integrated Transport Research Lab, ITRL.
    Susilo, Y. O.
    Gidofalvi, Gyözö
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Naqavi, Fatemeh
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Transport och systemanalys.
    Nybacka, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Teknisk mekanik, Farkostteknik och Solidmekanik.
    Towards a better understanding of the health impacts of one’s movement in space and time2022Inngår i: Journal of Literature and Science, E-ISSN 1754-646X, s. 1-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To better understand the interactions between physical built environment conditions and one’s well-being, we created a passive data collector for travellers and made the first step towards an explanatory model based on psychophysiological relations. By measuring biometric information from select trial participants we showed how different controlled factors are affecting the heart rate of the participants. A regression model with the impact factors such as speed, location, time and activity (accelerometer data) reveals how the factors relate to each other and how they correlate with the recorded individual’s heart rates throughout the observed period. For examples, the results show that the increase in movement speed is not linearly correlated with the heart rate. One’s heart rate would increase significantly when the individual reaches brisk walking and running speed, but not before nor after. Early morning and early evening time slots were the time where the observed individuals have the highest heart rates, which may correlate to individuals’ commute activities. Heart rates at the office would be lower than at home, which might correlate to more physical activities in the household. 

  • 28. Patil, V
    et al.
    Naik, N
    Gadicherla, S
    Smriti, K
    Raju, Adithya
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem.
    Rathee, U
    Biomechanical Behavior of Bioactive Material in Dental Implant: A Three-Dimensional Finite Element Analysis2020Inngår i: Scientific World Journal, ISSN 2356-6140, Vol. 2020Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dental implants are widely accepted for the rehabilitation of missing teeth due to their aesthetic compliance, functional ability, and great survival rate. The various components in implant design like thread design, thread angle, pitch, and material used for manufacturing play a critical role in its success. Understanding these influencing factors and implementing them properly in implant design can reduce cases of potential implant failure. Recently, finite element analysis (FEA) is being widely used in the field of health sciences to solve problems in designing medical devices. It provides valid and accurate assessment in the clinical and in vitro analysis. Hence, this study was conducted to evaluate the impact of thread design of the implant and 3 different bioactive materials, titanium alloy, graphene, and reduced graphene oxide (rGO) on stress, strain, and deformation in the implant system using FEA. In this study, the FEA model of the bones and the tissues are modeled as homogeneous, isotropic, and linearly elastic material with a titanium implant system with an assumption of it 100% osseointegrated into the bone. The titanium was functionalized with graphene and graphene oxide. A modeling software tool Catia¯ and Ansys Workbench¯ is used to perform the analysis and evaluate the von Mises stress distribution, strain, and deformation at the implant and implant-cortical bone interface. The results showed that the titanium implant with a surface coating of graphene oxide exhibited better mechanical behavior than graphene, with mean von Mises stress of 39.64 MPa in pitch 1, 23.65 MPa in pitch 2, and 37.23 MPa in pitch 3. It also revealed that functionalizing the titanium implant will help in reducing the stress at the implant system. Overall, the study emphasizes the use of FEA analysis methods in solving various biomechanical issues about medical and dental devices, which can further open up for invivo study and their practical uses.

  • 29. Pedersen, T. O.
    et al.
    Xing, Z.
    Finne-Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hellem, S.
    Mustafa, K.
    Hyperbaric oxygen stimulates vascularization and bone formation in rat calvarial defects2013Inngår i: International Journal of Oral and Maxillofacial Surgery, ISSN 0901-5027, E-ISSN 1399-0020, Vol. 42, nr 7, s. 907-914Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hyperbaric oxygen (HBO) therapy is used to treat or prevent tissue necrosis in patients undergoing irradiation. Many such patients require reconstructive surgery, but little is known of the effects of HBO on bone vascularization and regeneration. In this study, copolymer poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) scaffolds were implanted into critical-sized calvarial defects in Wistar rats. The animals were randomly allotted to hyperbaric or normobaric oxygen groups. The treatment group received five sessions weekly for 90 min at increased atmospheric pressure, for up to 4 weeks. Samples were retrieved at weeks 2 and 8, i.e. after a total of 10 and 20 sessions, respectively. The samples were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and histology at week 2, and radiographically and histologically at week 8. At week 2, defects treated with HBO exhibited greater numbers of cells positive for the endothelial marker CD31, up-regulated gene expression of osteogenic markers, and down-regulated expression of pro-inflammatory cytokines. At week 8, radiographic examination revealed that calvarial defects subjected to HBO exhibited a higher percentage of radiopacities than normobaric controls, and histological examination disclosed enhanced bone healing. These results confirmed that HBO treatment was effective in stimulating vascularization and bone formation in rat calvarial defects.

  • 30.
    Plangger, K.
    et al.
    Kings Coll London, Dept Management, London SE1 9NH, England..
    Bredican, John
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Industriell marknadsföring.
    Mills, A. J.
    Simon Fraser Univ, Beedie Sch Business, Vancouver, BC V6C 1W6, Canada..
    Armstrongin, J.
    AARM Dent Grp, Vancouver, BC V6E 4M9, Canada..
    Smart dental practice: capitalising on smart mobile technology2015Inngår i: British Dental Journal, ISSN 0007-0610, E-ISSN 1476-5373, Vol. 219, nr 3, s. 135-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To keep pace with consumer adoption of smart mobile devices, such as smartphones and tablets, and the applications ('apps') developed for these devices, dental professionals should consider how this technology could be used to simultaneously improve both patient service experiences and dental practice management. Using U-Commerce as a theoretical lens, this article discusses the potential value of smart mobile technology to the dental practice context, with a particular focus on the unique and customisable capabilities of apps. To take full advantage of this technology, a process is outlined for identifying and designing bespoke dental apps that takes into account the unique advantages of these devices. Dental practices, with increasing financial and competitive pressures, may improve the efficiency and profitability of operations and better manage patients, employees and stakeholders by integrating smart mobile technology.

  • 31.
    Powell, Nelson
    et al.
    Stanford University School of Medicine.
    Mihaescu, Mihai
    Aerospace Engineering, University of Cincinnati.
    Mylavarapu, Goutham
    Aerospace Engineering, University of Cincinnati.
    Weaver, Edward
    University of Washington.
    Guilleminault, Christian
    Stanford University School of Medicine.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Patterns in pharyngeal airflow associated with sleep-disordered breathing2011Inngår i: Sleep Medicine, ISSN 1389-9457, E-ISSN 1878-5506, Vol. 12, nr 10, s. 966-974Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: To establish the feasibility of a noninvasive method to identify pharyngeal airflow characteristics in sleep-disordered breathing.

    Methods: Four patients with sleep-disordered breathing who underwent surgery or used positive airway pressure devices and four normal healthy controls were studied. Three-dimensional CT imaging and computational fluid dynamics modeling with standard steady-state numerical formulation were used to characterize pharyngeal airflow behavior in normals and pre-and post-treatment in patients. Dynamic flow simulations using an unsteady approach were performed in one patient.

    Results: The pre-treatment pharyngeal airway below the minimum cross-sectional area obstruction site showed airflow separation. This generated recirculation airflow regions and enhanced turbulence zones where vortices developed. This interaction induced large fluctuations in airflow variables and increased aerodynamic forces acting on the pharyngeal wall. At post-treatment, for the same volumetric flow rate, airflow field instabilities vanished and airflow characteristics improved. Mean maximum airflow velocity during inspiration reduced from 18.3 ± 5.7 m/s pre-treatment to 6.3 ± 4.5 m/s post-treatment (P = 0.002), leading to a reduction in maximum wall shear stress from 4.8 ± 1.7 Pa pre-treatment to 0.9 ± 1.0 Pa post-treatment (P = 0.01). The airway resistance improved from 4.3 ± 1.4 Pa/L/min at pre-treatment to 0.7 ± 0.7 Pa/L/min at post-treatment (P = 0.004). Post-treatment airflow characteristics were not different from normal controls (all P ⩾ 0.39).

    Conclusions: This study demonstrates that pharyngeal airflow variables may be derived from CT imaging and computational fluid dynamics modeling, resulting in high quality visualizations of airflow characteristics of axial velocity, static pressure, and wall shear stress in sleep-disordered breathing.

  • 32.
    Rodriguez, Raul
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Moreno, LuisKTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Modelling of an Upflow Anaerobic Sludge Blanket reactor2010Collection/Antologi (Annet vitenskapelig)
    Abstract [en]

    A model describing both physical and biological processes in Upflow Anaerobic Sludge Blanket (UASB) reactors was developed The main objective of the modelling was to take into account the transient growth of the microorganisms from the start-up of the reactor until a steady state is reached In addition, the model considers the degradation of the substrate and its reaction with the biomass, which is present in the form of spherical granules of different sizes For the degradation of the substrate within the granule, the mass transport through the stagnant film around the granule and the intra-particle diffusion are accounted for, together with the specific reaction rate In the model, the growth of the biomass follows the Contois kinetics The amount of biomass reaches a steady state after weeks or months Biomass is generated when substrate is degraded and a given fraction of biomass disappears per unit of time, which is determined by the decay constant The value of this constant is taken from the literature The model also considers that a fraction of the biomass may be carried out by the water flow The model was solved by using COMSOL Multiphysics Data from the literature was used in order to illustrate the processes occurring in the UASB reactor Modelling can be a useful tool for the design and optimization of UASB reactors

  • 33.
    Råvik, Mattias
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Influence of Escherichia coli feedstock properties on the performance of primary protein purification2006Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Abstract

    The aim of the present study was to increase the understanding of how the cell surface properties affect the performance of unit operations used in primary protein purification. In particular, the purpose was to develop, set up and apply methods for studies of cell surface properties and cell interactions.

    A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Escherichia coli strains were used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cells and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the strains were observed. The physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and were compared with the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA).

    Studies of the behaviour of the model cells on stirred cell filtration and in an interaction test with different expanded bed adsorption (EBA) adsorbents were performed. It could be concluded that especially one of the strains behaved differently. Differences in the properties of the model cells were indicated by microelectrophoresis and aqueous two-phase partitioning which to some extent correlated with observed differences in behaviour during filtration and in an interaction test with EBA adsorbents.

    The impact of high-pressure homogenisation of E. coli cell extract was examined, with a lab scale and a pilot scale technique. The DNA-fragmentation, visualised with agarose gel electrophoresis, and the resulting change in viscosity was analysed. A short homogenisation time resulted in increased viscosity of the process solution that correlated with increased concentration of released non-fragmented DNA. With longer homogenisation time the viscosity decreased with increasing degree of DNA-fragmentation.

    The results show that strain dependant cell surface properties of E. coli may have an impact on several primary steps in downstream processing.

    Fulltekst (pdf)
    FULLTEXT01
  • 34.
    Ríos Bayona, Francisco
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Johansson, Fredrik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Ivars, Diego Mas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik. SKB Swedish Nucl Fuel & Waste Management Co, Solna, Sweden..
    Sanchez-Juncal, Abel
    A&P Consultants, Edmonton, AB, Canada.;Previously Itasca Consultants AB, Stockholm, Sweden..
    Bolin, Axel
    Swedish Transport Adm, Stockholm, Sweden..
    Using PFC2D to simulate the shear behaviour of joints in hard crystalline rock2022Inngår i: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 81, nr 9, artikkel-id 381Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Significant uncertainties remain regarding the assessment of the peak shear strength of rock joints. In recent years, Particle Flow Code (PFC) has been used to simulate shear tests of rock joints. Although previous studies showed PFC's capability to simulate rock joint shear behaviour, it is uncertain how different parameters in PFC should be combined to realistically capture roughness and strength of asperities in contact of actual rock joints. Under low normal stresses, the shear behaviour of well-mated hard crystalline joints is governed by the interaction between asperities of some tenths of a millimetre. This paper investigates the capability of PFC2D to realistically simulate the peak shear strength of hard crystalline rock joints under different constant normal stress magnitudes. The simulated two-dimensional profiles were selected from the digitised joint surface obtained with optical scanning measurements. To realistically capture surface roughness and asperity strength in PFC2D, different values of joint segment length, particle resolution per segment, and bond strength between particles were studied and calibrated while taking into account the laboratory observations. The results of the numerical simulations in the PFC2D environment show that the simulated peak shear strength using the profile containing the steepest asperity is in good agreement with that measured in the laboratory. The joint profile needs to be represented by both a magnitude of segment length that captures the grain size, and at least two particles per segment. The bond strength calibration needs to account for both asperity size and the number of particles in contact during shearing.

  • 35.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Rowell, Roger Max
    Larsson Brelid, Pia
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Westin, Mats
    Alfredsen, G.
    Improved Durability and Moisture Sorption Characteristics of Extruded WPCs made from Chemically Modified Wood2007Inngår i: Proceedings of the 9th International Conference on Wood & Biofiber Plastic Composites., 2007, s. 251-256Konferansepaper (Fagfellevurdert)
  • 36.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Walkenström, Pernilla
    IFP Research, Swedish Institute for Fibre and Polymer Research.
    Nyström, B.
    SICOMP, Swedish Institute of Composites.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson Brelid, Pia
    SP Trätek, Technical Research Institute of Sweden.
    Micromorphology, moisture sorption and mechanical properties of a biocomposite based on acetylated wood particles and cellulose ester2007Inngår i: Wood Material Science and Engineering, ISSN 1748-0272, Vol. 3-4, nr 2, s. 106-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the major issues in a long-term perspective for the use of wood-plastic composites (WPCs) in outdoor applications is the moisture sensitivity of the wood component and the consequent dimensional instability and susceptibility to biological degradation of the composite. In this work, the effects of using an acetylated wood component and a cellulose ester as matrix on the micromorphology, mechanical performance and moisture uptake of injection-moulded WPCs have been studied. Composites based on unmodified and acetylated wood particles, specially designed with a length-to-width ratio of about 5-7, combined with both cellulose acetate propionate (CAP) and polypropylene (PP) matrices were studied. The size and shape of the wood particles were studied before and after the processing using light microscopy, and the micromorphology of the composites was studied using a newly developed surface preparation technique based on ultraviolet laser irradiation combined with low-vacuum scanning electron microscopy (LV-SEM). The water vapour sorption in the composites and the effect of accelerated weathering were measured using thin samples which were allowed to reach equilibrium moisture content (EMC). The length-to-diameter ratio was only slightly decreased for the acetylated particles after compounding and injection moulding, although both the unmodified and the acetylated particles were smaller in size after the processing steps. The tensile strength was about 40% higher for the composite based on acetylated wood than for the composite with unmodified wood using either CAP or PP as matrix, whereas the notched impact strength of the composite based on acetylated wood was about 20% lower than those of the corresponding unmodified composites. The sorption experiments showed that the EMC was 50% lower in the composites with an acetylated wood component than in the composites with an unmodified wood component. The choice of matrix material strongly affected the moisture absorptivity of the WPC. The composites with CAP as matrix gained moisture more rapidly than the composites with PP as matrix. It was also found that accelerated ageing in a Weather-Ometer® significantly increased the moisture sensitivity of the PP-based composites.

  • 37.
    Segerholm, Kristoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Wålinder, Magnus
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Larsson Brelid, Pia
    Walkenström, Pernilla
    Westin, Mats
    Wood plastic composites made from acetylated wood: Effects on water vapour sorption behaviour and durability2005Inngår i: Proceedings of the 9th European Panel Products Symposium, 2005, s. 233-242Konferansepaper (Fagfellevurdert)
  • 38. Shen, M.
    et al.
    Wang, C.
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi. KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. Shanghai Institute of Technology.
    Mechanical Properties of ZrO2 TPMS Structures Prepared by DLP 3D Printing2019Inngår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2019, nr 1Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Compressive strength is one of the most important mechanical properties for cellular ceramics. But the dependence of compressive strength of highly porous cellular ceramic structures on porosity remains unclear due to the limit of available methods for making such strong structures based on specific structural designs. In this paper, the TPMS structures, namely P-cell, and neovius structure, were prepared based on the DLP 3D printing technology. Samples with various unit cells were fabricated with zirconia. The relative density of the sintered samples exceeds 99%. The effects of cell number on the compressive strength and deformation of the model were investigated. Samples with similar relative densities exhibited comparable mechanical property in aspect of compressive strength. It is very interesting that the cell number eventually only influence the total strain.

  • 39.
    Shen, Minhao
    et al.
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Zhao, Weiming
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Xing, Bohang
    Tianjin Univ, Sch Mat Sci & Engn, Tianjin 300072, Peoples R China..
    Sing, Ying
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Gao, Shuyue
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Wang, Cao
    Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Shanghai Inst Technol, Sch Mat Sci & Engn, Shanghai 201418, Peoples R China..
    Effects of exposure time and printing angle on the curing characteristics and flexural strength of ceramic samples fabricated via digital light processing2020Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, nr 15, s. 24379-24384Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45 degrees exhibits the worst performance.

  • 40.
    Svagan, Anna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Azizi Samir, My
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Nanocomposite cellulose-starch foams prepared by lyophilizationManuskript (Annet vitenskapelig)
  • 41. Tellefsen, G.
    et al.
    Liljeborg, Anders V G
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Johannsen, A.
    Johannsen, G.
    The role of the toothbrush in the abrasion process2011Inngår i: International Journal of Dental Hygiene, ISSN 1601-5029, E-ISSN 1601-5037, Vol. 9, nr 4, s. 284-290Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: To evaluate the relative abrasivity of different toothbrushes both qualitatively and quantitatively. Materials and Methods: Acrylic plates were exposed to brushing in a brushing machine with ten different toothbrushes with water alone and with a toothpaste. The results were evaluated using a profilometer after one and 6 h of brushing (corresponding to 2000 and 12 000 double strokes, respectively). A surface roughness value (Ra-value) and also a volume loss value were calculated from the profilometer measurements. These values were then compared to each other. Results: The results showed that brushing with water alone caused less abrasion than when a toothpaste was added. Six-hour brushing with water caused less abrasion than 1 h with a toothpaste. The number of filaments or filament diameter influenced the results in various ways. When brushing with water, the harder toothbrush (Jordan Medium) caused more abrasion (higher Ra-value), but when adding the toothpaste, the softer toothbrush (Jordan soft) caused more abrasion after 12 000 double strokes. Conclusion: Besides supporting the fact that a toothpaste is needed to create a significant abrasion, this study also showed that a softer toothbrush can cause as much and in some cases more abrasion than harder ones. When conducting abrasivity studies, it is important to look at both the quantitative and qualitative aspect of abrasivity.

  • 42. Vollmer, Antje
    et al.
    Voiges, Kristin
    Bork, Christian
    Fiege, Kathrin
    Cuber, Katja
    Mischnick, Petra
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Comprehensive analysis of the substitution pattern in dextran ethers with respect to the reaction conditions2009Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 395, nr 6, s. 1749-1768Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dextrans from Leuconostoc ssp., alpha-1,6-linked glucans branched at O-3, were O-methylated in DMSO with lithium dimsyl and methyl iodide under various conditions. Methyl substituent distribution was comprehensively studied in the terminal, internal, and branched glucosyl units and along and over the dextran macromolecules. The order of reactivity was O-2>O-4 >= O-3. The methyl pattern in the glucosyl units significantly deviates from a random distribution with enhanced amounts of un- and trisubstituted moieties. This deviation was found to proceed on macromolecular level by means of ESI-MS of perdeuteromethylated and partially depolymerized methyl dextrans. Heterogeneity was much more pronounced than for methyl amylose prepared under comparable conditions. DS gradients in and over the material are discussed with respect to dextran structure and the mechanism of Li dimsyl alkylation. For comparison, cyanoethyl dextrans were prepared by sodium hydroxide catalyzed addition of acrylonitrile. Monomer analysis of cyanoethyl dextrans revealed that this thermodynamically controlled reaction gave a random substitution pattern with 48% of cyanoethyl groups at O-2, 33% at O-4, and 19% at O-3.

  • 43.
    Wennstam, Lisa
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Inte bara hus som hus: Ett underlag till diskussion kring ett lämpligt innehåll i en samtida arkitekturpolitik i Lidköpings kommun2022Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Under 2018, mitt i en global miljökris, en nationell ökning av sociala klyftor och segregation, accepterade den svenska regeringen en ny nationell arkitekturpolitik, Politik för Gestaltad livsmiljö (Policy for Designed Living Environment). Politiken är förankrad i en marknadsekonomi och förmedlar olika strategier för hållbar utveckling. De sträcker sig från social hållbarhetsteorier om inkludering och tillgänglighet, ner till resurshantering, lokalt hantverk och återvinning av byggmaterial. Politiken är ett resultat av en förändrad förståelse för arkitektur, arkitekturpolitik, arkitekten och hans eller hennes roll, eller som teoretiker Kaminer och Kossak skulle hävda: roller.

    Detta arbete i Hållbar samhällsplanering och stadsutformning utforskar och presenterar vad som kan vara ett relevant innehåll i arkitekturbestämmelser i Lidköpings kommun. Det är resultatet av en dokumentstudie som innehåller den svenska nationella arkitekturpolitiken, lokala tolkningar av den i 12 kommuner över hela Sverige och Lidköpings kommuns Stadsutvecklingsplan för staden Lidköping. Samt, en enkät och en utökad dialog i form av en designworkshop med sex ungdomar i Lidköping om Lidköpings framtid. Detta projekt syftar till att stödja utvecklingen av lokala tolkningar av den svenska nationella politiken, och fungera som en bas för diskussion kring ämnet arkitekturpolitik i Sverige.

    Fulltekst (pdf)
    fulltext
  • 44.
    Winzell, Anders
    KTH, Skolan för bioteknologi (BIO).
    Analysis of Genes and Proteins Involved in Wood Formation2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    SAMMANFATTNING

    Vedbildning är en underliggande mekanism för så skilda områden som industri, boende och en hållbar miljö. Vedbildning sker i det vaskulära kambiet där organiserade celldelningar åtföljs av differentiering till specialiserade vedceller. Ved består av sekundärt xylem som är starka, stora celler med tjocka cellväggar som är lignifierade. Dessa celler transporterar vatten och näringsämnen samt ger trädet dess styrka. Grunden för de starka cellerna är en avancerad komposit bestående av cellulosafibrer tvärbundna av hemicellulosa och slutligen ingjutet i lignin. Denna fiberkomposit är den sekundära cellväggen i vedartade växter. Celldelning och differentiering regleras genom att sätta igång och stänga av gener. Proteiner som kodas av dessa gener utför de viktigaste funktionerna i cellerna. De styr hela maskineriet som upprätthåller cellernas struktur och funktion, underhåller tillväxt samt tillverkar nödvändiga produkter såsom cellväggskolhydraterna.

    Träbioteknologiforskningsgruppen har varit en del av ett kraftfullt åtagande att identifiera de proteiner som är ansvariga för nyckelprocesser i vedbildning. Detta har utförts genom att övervaka genexpressionen vid olika tidpunkter av vedcellsmognad i Populus tremula x tremuloides. Här beskriver vi undersökningen av proteiner som är inblandade i cellexpansion och bildandet av sekundär cellvägg liksom utvecklandet av ett modellsystem som kommer vara en hjälp i den funktionella analysen av cellulosabiosyntes. Expansin är ett protein som verkar i cellexpansionen i alla växtens vävnader. Vi har studerat ett expansin, PttEXPA1, som visat sig vara särskilt närvarande i celler som genomgår vedbildning. Dessutom har vi undersökt glykosyltransferaser som tycks spela en viktig roll i bildandet av sekundär cellvägg. En av dessa, PttGT43A har uttryckts i jästen Pichia pastoris och i baculovirusinfekterade insektsceller. Dessvärre var proteinnivåerna för låga för biokemisk karakterisering. Dessutom har vi demonstrerat att flytande cellkulturer av hybridasp kan användas som ett modellsystem för cellulosabiosyntes.

    Genom att bemästra proteinerna som är ansvariga för vedbildning får vi verktyg att utveckla skogsproduktsmarknaden. En vision är nya produkter som till exempel träd som växer snabbare, ändrade fiberegenskaper, produktion av vedkolhydrater såväl som utvecklandet av intelligenta material genom biomimetisk ingenjörskonst.

    Fulltekst (pdf)
    FULLTEXT01
  • 45.
    Yan, Hongji
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap. AIMES - Center for the Advancement of Integrated Medical and Engineering Sciences at KI Karolinska Institutet; Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    De Deus, Gustavo
    Department of Endodontics, Universidade Federal Fluminense, R. Mario Santos Braga, 30 - Centro, Niteroi - RJ, 24020-140, Brazil.
    Kristoffersen, Ida Marie
    Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    Wiig, Elisabeth
    Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    Reseland, Janne Elin
    Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    Johnsen, Gaute F.
    Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    Silva, Emmanuel J.N.L.
    Department of Endodontics, Grande Rio University, Duque de Caxias, Brazil.
    Haugen, Håvard J.
    Department of Biomaterials, Institute of Clinical Dentistry, Faculty of Odontology, University of Oslo, 0317 Oslo, Norway.
    Regenerative Endodontics by Cell Homing: A Review of Recent Clinical trials2023Inngår i: Journal of Endodontics, ISSN 0099-2399, E-ISSN 1878-3554, Journal of Endodontics, ISSN 0099-2399, Vol. 49, nr 1, s. 4-17Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Introduction: The conventional treatment for irreversibly inflamed or necrotic teeth is root canal treatment or apexification. Regenerative endodontics aims to regenerate the damaged “pulp-like” tissue, which can preserve the teeth' vitality and sensitivity while avoiding necrosis. The main clinical benefit is root maturation. The “pulp-like” tissue does not refer to regenerated pulp tissue with an odontoblastic layer or the formation of pulp-dentin complexes. The cell homing technique is built on endogenous stem cells and their capacity to regenerate tissue. Cell homing refers to endogenous cells’ migration or infiltration into the cite when stimulated by physiochemical or biological stimuli or by passive flow with a blood clot from the apical tissue. Its Regenerative Endodontic Procedures success criteria are defined by the American Association of Endodontists. The purpose of this article is to provide an overview of vital pulp tissue and various strategies to promote regeneration of damaged pulp tissue. The cell homing technique will be reviewed through clinical trials. Methods: We performed a comprehensive literature review on a total of nine clinical trials of regenerative endodontics using the cell-homing technique based on three databases and duplicate manuscripts were removed. Results: Regenerative endodontics using the cell-homing technique shows promising results that can be translated into clinical practice. However, a favorable result was observed in immature teeth, and the results are contradictory in mature teeth. Conclusion: Regeneration therapy is an attractive new alternative to conventional endodontic treatments. Preservation of vitality and continuation of root development in damaged teeth would be a clear advantage.

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