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Publications (10 of 236) Show all publications
Kertmen, A., Torruella, P., Coy, E., Yate, L., Nowaczyk, G., Gapinski, J., . . . Andruszkiewicz, R. (2017). Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core-Shell Structures upon Nanoemulsion Fusion. Langmuir, 33(39), 10351-10365
Open this publication in new window or tab >>Acetate-Induced Disassembly of Spherical Iron Oxide Nanoparticle Clusters into Monodispersed Core-Shell Structures upon Nanoemulsion Fusion
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2017 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 39, p. 10351-10365Article in journal (Refereed) Published
Abstract [en]

It has been long known that the physical encapsulation of oleic acid-capped iron oxide nanoparticles (OA-IONPs) with the cetyltrimethylammonium (CTA(+)) surfactant induces the formation of spherical iron oxide nanoparticle clusters (IONPCs). However, the behavior and functional properties of IONPCs in chemical reactions have been largely neglected and are still not well-understood. Herein, we report an unconventional ligand-exchange function of IONPCs activated when dispersed in an ethyl acetate/acetate buffer system. The ligand exchange can successfully transform hydrophobic OA-IONP building blocks of IONPCs into highly hydrophilic, acetate-capped iron oxide nanoparticles (Ac-IONPs). More importantly, we demonstrate that the addition of silica precursors (tetraethyl orthosilicate and 3-aminopropyltriethoxysilane) to the acetate/oleate ligand-exchange reaction of the IONPs induces the disassembly of the IONPCs into monodispersed iron oxide-acetate-silica core-shell-shell (IONPs@acetate@SiO2) nanoparticles. Our observations evidence that the formation of IONPs@acetate@SiO2 nanoparticles is initiated by a unique micellar fusion mechanism between the Pickering-type emulsions of IONPCs and nanoemulsions of silica precursors formed under ethyl acetate buffered conditions. A dynamic rearrangement of the CTA(+)-oleate bilayer on the IONPC surfaces is proposed to be responsible for the templating process of the silica shells around the individual IONPs. In comparison to previously reported methods in the literature, our work provides a much more detailed experimental evidence of the silica-coating mechanism in a nanoemulsion system. Overall, ethyl acetate is proven to be a very efficient agent for an effortless preparation of monodispersed IONPs@acetate@SiO2 and hydrophilic Ac-IONPs from IONPCs.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-217041 (URN)10.1021/acs.langmuir.7b02743 (DOI)000412718700025 ()28895402 (PubMedID)2-s2.0-85030677707 (Scopus ID)
Note

QC 20171101

Available from: 2017-11-01 Created: 2017-11-01 Last updated: 2018-02-26Bibliographically approved
Lobov, G. S., Marinins, A., Etcheverry, S., Zhao, Y., Vasileva, E., Sugunan, A., . . . Popov, S. (2017). Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component. Optical Materials Express, 7(1), 52-61
Open this publication in new window or tab >>Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component
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2017 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, no 1, p. 52-61Article in journal (Refereed) Published
Abstract [en]

Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/mu m. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-202445 (URN)10.1364/OME.7.000052 (DOI)000392205600007 ()2-s2.0-85008157720 (Scopus ID)
Funder
Swedish Research Council, VR-SRL 2012-4421Swedish Research Council, VR-SRL 2013-6780Swedish Foundation for Strategic Research , EM11-0002
Note

QC 20170306

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-11-29Bibliographically approved
Nikkam, N., Toprak, M., Dutta, J., Al-Abri, M., Myint, M. T., Souayeh, M. & Mohseni, S. M. (2017). Fabrication and thermo-physical properties characterization of ethylene glycol-MoS2 heat exchange fluids. International Communications in Heat and Mass Transfer, 89, 185-189
Open this publication in new window or tab >>Fabrication and thermo-physical properties characterization of ethylene glycol-MoS2 heat exchange fluids
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2017 (English)In: International Communications in Heat and Mass Transfer, ISSN 0735-1933, E-ISSN 1879-0178, Vol. 89, p. 185-189Article in journal (Refereed) Published
Abstract [en]

This study reports on the fabrication and thermo-physical properties evaluation of ethylene glycol (EG) based heat exchange fluids containing molybdenum disulfide nanoparticles (MoS2 NPs) and micrometer sized particles (MPs). For this purpose, MoS2 NPs and MPs (with average size of 90 nm and 1.2 mu m; respectively) were dispersed and stabilized in EG with particle loading of 0.25, 0.5, 1 wt%. To study the real effect of MoS2 NP/MP the use of surfactants was avoided and ultrasonic agitation was used for dispersion and preparation of stable MoS2 NFs/MFs. The objectives were investigation of impact of MoS2 particle size (including NP/MP) and particle loading on thermo-physical properties of EG based MoS2 NFs/MFs including thermal conductivity (TC) and viscosity of NFs/MFs at 20 degrees C. All suspensions (NFs/MFs) exhibited a higher TC than the EG as base liquid and NFs showed higher TC enhancement values than the MFs. A TC enhancement of 16.4% was observed for NFs containing 1 wt % MoS2 NPs while the maximum increase in viscosity of 9.7% was obtained for the same NF at 20 degrees C. It indicates this NF system may have some potential to be utilized in heat transfer applications.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2017
Keywords
MoS2 nanoparticles, MoS2 microparticles, Nanofluids, Microfluids thermal conductivity, Viscosity, Thermo-physical property
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-221874 (URN)10.1016/j.icheatmasstransfer.2017.10.011 (DOI)000419412500021 ()
Note

QC 20180131

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2018-01-31Bibliographically approved
Mohamed, A., Yousef, S., Ali Abdelnaby, M., Osman, T. A., Hamawandi, B., Toprak, M. S., . . . Uheida, A. (2017). Photocatalytic degradation of organic dyes and enhanced mechanical properties of PAN/CNTs composite nanofibers. Separation and Purification Technology, 182, 219-223
Open this publication in new window or tab >>Photocatalytic degradation of organic dyes and enhanced mechanical properties of PAN/CNTs composite nanofibers
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2017 (English)In: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 182, p. 219-223Article in journal (Refereed) Published
Abstract [en]

This work describes the enhanced mechanical properties of the composite nanofibers and the photodegradation of two organic dyes using PAN/CNTs under UV irradiation at different volume concentration (0.05, 0.1, 0.2, and 0.3 wt.%). The composite nanofibers was performed with polyacrylonitrile (PAN), and carbon nanotubes (CNTs) by electrospinning process. The composite nanofibers structure and morphology is characterized by XRD, FTIR, SEM, and TEM. The result indicates that with increasing CNTs content, the mechanical properties of the composite nanofibers was enhanced, and became more elastic, and the elastic modulus increased drastically. The results of mechanical properties exhibit improvements in tensile strengths, and elastic modulus by 38% and 84% respectively, at only 0.05 wt.% CNTs. Moreover, photocatalytic degradation performance in short time and low power intensity was achieved comparison to earlier reports.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Composite nanofibers, Mechanical properties, Photodegradation, Carbon, Carbon nanotubes, Elastic moduli, Irradiation, Tensile strength, Yarn, Electrospinning process, Organic dye, Photo catalytic degradation, Polyacrylonitrile (PAN), Structure and morphology, UV irradiation, Volume concentration, Nanofibers
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-207443 (URN)10.1016/j.seppur.2017.03.051 (DOI)000401393700025 ()2-s2.0-85016937303 (Scopus ID)
Note

QC 20170523

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2017-06-14Bibliographically approved
Mohamed, A., Osman, T. A., Toprak, M. S., Muhammed, M. & Uheida, A. (2017). Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions. Chemosphere, 180, 108-116
Open this publication in new window or tab >>Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions
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2017 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 180, p. 108-116Article in journal (Refereed) Published
Abstract [en]

A novel composites nanofiber was synthesized based on PAN-CNT/TiO2-NH2 nanofibers using electrospinning technique followed by chemical modification of TiO2 NPs. PAN-CNT/TiO2-NH2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
Keywords
Arsenic adsorption, Composite nanofibers, Electrospinning, Isotherm, Kinetics
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-207283 (URN)10.1016/j.chemosphere.2017.04.011 (DOI)000401880500013 ()2-s2.0-85017101033 (Scopus ID)
Note

QC 20170619

Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2017-06-19Bibliographically approved
Saleemi, M., Tafti, M. Y., Jacquot, A., Jaegle, M., Johnson, M. & Toprak, M. S. (2016). Chemical Synthesis of Iron Antimonide (FeSb2) and Its Thermoelectric Properties. Inorganic Chemistry, 55(4), 1831-1836
Open this publication in new window or tab >>Chemical Synthesis of Iron Antimonide (FeSb2) and Its Thermoelectric Properties
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2016 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 4, p. 1831-1836Article in journal (Refereed) Published
Abstract [en]

Low temperature thermoelectric (TE) materials are in demand for more efficient cooling and power generation applications. Iron antimonide (FeSb2) draws great attention over the past few years because of its enhanced power factor values. Polycrystalline bulk FeSb2 nanopowder was prepared via a low-temperature molten salts approach followed by subsequent thermal treatment in synthetic air and hydrogen gas for calcination and reduction reactions, respectively. Structural analysis confirms the desired final phase with submicrometer grain size and high compaction density after consolidation using spark plasma sintering (SPS). TE transport properties revealed that the material is n-type below 150 K and p-type above this temperature; this suggests antimony vacancies in FeSb2. The electrical conductivity increased significantly, and the highest conductivity achieved was 6000 S/cm at 100 K. The maximum figure-of-merit, ZT, of 0.04 is achieved at 500 K, which is about 6 times higher than the earlier reported state-of-the art ZT value for the same material.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-184039 (URN)10.1021/acs.inorgchem.5b02658 (DOI)000370395000055 ()26836130 (PubMedID)2-s2.0-84958818272 (Scopus ID)
Note

QC 20160323

Available from: 2016-03-23 Created: 2016-03-22 Last updated: 2017-11-30Bibliographically approved
Mohamed, A., El-Sayed, R., Osman, T. A., Toprak, M., Muhammed, M. A. & Uheida, A. (2016). Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water. Environmental Research, 145, 18-25
Open this publication in new window or tab >>Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water
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2016 (English)In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 145, p. 18-25Article in journal (Refereed) Published
Abstract [en]

In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO2 nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity compared to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Carbon nanotubes (CNTs), Composite nanofibers, Electrospinning, Organic contaminants, Photocatalytic
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-181428 (URN)10.1016/j.envres.2015.09.024 (DOI)000368218700003 ()2-s2.0-84947786246 (Scopus ID)
Note

QC 20160204. QC 20160220

Available from: 2016-02-04 Created: 2016-02-02 Last updated: 2017-11-30Bibliographically approved
Kurtan, U., Amir, M., Baykal, A., Sozeri, H. & Toprak, M. S. (2016). Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes. Journal of Nanoscience and Nanotechnology, 16(3), 2548-2556
Open this publication in new window or tab >>Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes
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2016 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 16, no 3, p. 2548-2556Article in journal (Refereed) Published
Abstract [en]

Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FTIR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water.

Place, publisher, year, edition, pages
American Scientific Publishers, 2016
Keywords
Magnetic Recyclable Nanocatalyst, Azo Dyes, Catalytic Reduction, Magnetic Properties
National Category
Condensed Matter Physics Nano Technology
Identifiers
urn:nbn:se:kth:diva-186568 (URN)10.1166/jnn.2016.11707 (DOI)000374153800060 ()2-s2.0-84960419370 (Scopus ID)
Note

QC 20160513

Available from: 2016-05-13 Created: 2016-05-13 Last updated: 2017-11-30Bibliographically approved
Khachatourian, M. A., Golestani-Fard, F., Sarpoolaky, H., Vogt, C., Vasileva, E., Mensi, M., . . . Toprak, M. S. (2016). Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties. Journal of Luminescence, 169, 1-8
Open this publication in new window or tab >>Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties
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2016 (English)In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 169, p. 1-8Article in journal (Refereed) Published
Abstract [en]

Red fluorescent emitting monodispersed spherical Y<inf>2</inf>O<inf>3</inf> nanophosphors with different Eu3+ doping concentrations (0-13 mol%) are synthesized by a novel microwave assisted urea precipitation, which is recognized as a green, fast and reproducible synthesis method. The effect of Eu3+ doping and calcination temperature on the structural characteristics and luminescence properties of particles is investigated in detail. The as prepared powders have (Y,Eu)(OH)(CO<inf>3</inf>) structure which converts to Y<inf>2</inf>O<inf>3</inf>:Eu3+ from 500 °C and become crystalline at higher temperatures. The crystallite size of nanophosphors increased from 15 nm to 25 nm as the calcination temperature increased from 700 °C to 1050 °C. The efficient incorporation of Eu3+ ions in cubic Y<inf>2</inf>O<inf>3</inf> host matrix is confirmed by the calculated X-ray Powder diffraction (XRPD) structural parameters. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show that the as obtained and calcined particles are spherical, monodispersed and non-agglomerated. The overall size of particles increases from 61±8 nm to 86±9 nm by increasing Eu3+ concentration from 0 mol% to 13 mol%. High resolution TEM revealed polycrystalline nature of calcined particles. The particles exhibit a strong red emission under ultraviolet (UV) excitation. The photoluminescence (PL) intensity of the peaks increases proportionally with Eu3+ concentration and the calcination temperature with no luminescence quenching phenomenon observed even for Y<inf>2</inf>O<inf>3</inf>:13%Eu3+. The fluorescent emission properties combined with the monodispersity and narrow size distribution characteristics make the Y<inf>2</inf>O<inf>3</inf>:Eu3+ heavy metal free nanophosphors applicable in fluorescence cell imaging and as fluorescence biolabels.

Keywords
Chemical synthesis, Luminescence, Microstructure, Optical properties, Phosphors, Rare earth compounds, Calcination, Chemical compounds, Crystallite size, Electron microscopy, Fluorescence, Heavy metals, High resolution transmission electron microscopy, Light emission, Photoluminescence, Powder metals, Scanning electron microscopy, Structural properties, Synthesis (chemical), Transmission electron microscopy, Urea, X ray powder diffraction, Calcination temperature, Luminescence properties, Luminescence quenching, Narrow size distributions, Photoluminescence intensities, Photoluminescence properties, Structural characteristics, Ultraviolet excitations, Europium
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-175601 (URN)10.1016/j.jlumin.2015.08.059 (DOI)000365604700001 ()2-s2.0-84941767189 (Scopus ID)
Note

QC 20151103

Available from: 2015-11-03 Created: 2015-10-19 Last updated: 2017-12-01Bibliographically approved
Kim, S.-H., Kim, M. C., Kim, M.-S., Ahn, J. P., Moon, K.-S., Koo, S. M., . . . Kim, D. K. (2016). Nanophase oxalate precursors of thermoelectric CoSb3 by controlled coprecipitation predicted by thermodynamic modeling. Advanced Powder Technology, 27(2), 773-778
Open this publication in new window or tab >>Nanophase oxalate precursors of thermoelectric CoSb3 by controlled coprecipitation predicted by thermodynamic modeling
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2016 (English)In: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 27, no 2, p. 773-778Article in journal (Refereed) Published
Abstract [en]

The precursors for the formation of thermoelectric skutterudite CoSb3 nanoparticles are predicted by thermodynamic modeling of the complex chemical species. Based on the results, equimolar mixture of CoC2O4 center dot 2H(2)O and Sb(C2O4) OH are successively co-precipitated under controlled conditions of pH = 2.7 and concentration of reactants. The as synthesized powder was decomposed at 350 degrees C to remove the organic molecules and further reduced to CoSb3 phase by heating at 530 degrees C under hydrogen flow. The obtained powder was consolidated by spark plasma sintering (SPS). CoSb3 prepared by controlled chemical co-precipitation has p-type behavior with a positive sign of the Seebeck coefficient. TE transport properties were measured, which revealed that the Seebeck coefficient increased 2.5 times with increasing the temperature and it is lower than the ball milled CoSb3. Thermal conductivity of sintered CoSb3 at 773 K starts from 0.06 W/cm K at room temperature and decreases to 0.04 W/cm K at 700 K, which is lower than the bulk counterpart. The ZT of coprecipitated CoSb3 and SPS consolidated at 773 K shows 2 times higher than the ball milled one. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Thermoelectric, Thermodynamic modeling, Co-precipitation, CoSb3
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-186005 (URN)10.1016/j.apt.2016.03.006 (DOI)000373525700059 ()2-s2.0-84981169048 (Scopus ID)
Note

QC 20160509

Available from: 2016-05-09 Created: 2016-04-29 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5678-5298

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