Zn0.95Ni0.05O and Zn0.90Ni0.05Al0.05O compositions of nanocrystallites are synthesised using the well recognised auto-combustion technique.The x-ray diffraction patterns demonstrate the phase pure characteristic wurtz...Zn0.95Ni0.05O and Zn0.90Ni0.05Al0.05O compositions of nanocrystallites are synthesised using the well recognised auto-combustion technique.The x-ray diffraction patterns demonstrate the phase pure characteristic wurtzite-type crystal structure with space group P63mc in both the compositions.The elemental incorporation of Ni and Al contents into the ZnO structure is confirmed by energy dispersive x-ray analysis.The micrographs of scanning electron microscopy show an approximate ordered morphology.The electrical resistivity is observed to decrease with the rising temperature,depicting the characteristic semiconductor behaviour of the samples.The lower values of resistivity and ferromagnetic interactions in the Al-doped sample correspond to an increase of carrier's density.It is observed that the carrier mediated mechanism is mainly responsible for ferromagnetism in ZnO-based diluted magnetic semiconductors.展开更多
The substitution of divalent cations of alkaline-earth elements in nanodimensional structures of rare-earth manganites produces advanced materials with potential electrical and magnetic functionalities.A systematic in...The substitution of divalent cations of alkaline-earth elements in nanodimensional structures of rare-earth manganites produces advanced materials with potential electrical and magnetic functionalities.A systematic investigation of La_(0.65)A_(0.35)MnO_(3)(A=Ca,Sr,Ba)materials synthesized with a modified citrate route adopting ethanol dehydration has been undertaken.The structural and morphological analyses are carried out by using x-ray diffraction and scanning electron microscopy,respectively.Resistivity measurements are performed in variation with temperature to study the electrical transport properties which are found to vary with the size of the A-site cationic radius.Room temperature magnetic measurements are carried out to investigate the type of magnetic phase present in materials.The stability of the magnetic phase and coercivity are found to be dependent on the size of nanocrystallites.展开更多
Objective: To explore RNA dependent RNA polymerase of Chikungunya virus(CHIKV) and develop T cell based epitopes with high antigenicity and good binding affinity for the human leukocyte antigen(HLA) classes as targets...Objective: To explore RNA dependent RNA polymerase of Chikungunya virus(CHIKV) and develop T cell based epitopes with high antigenicity and good binding affinity for the human leukocyte antigen(HLA) classes as targets for epitopes based CHIKV vaccine. Methods: In this study we downloaded 371 non-structural protein 4 protein sequences of CHIKV belonging to different regions of the world from the US National Institute of Allergy and Infectious Diseases(NIAID) virus pathogen resource database. All the sequences were aligned by using CLUSTALW software and a consensus sequence was developed by using Uni Pro U Gene Software version 1.2.1. PropredⅠand Propred software were used to predict HLAⅠ and HLAⅡ binding promiscuous epitopes from the consensus sequence of non-structural protein 4 protein. The predicted epitopes were analyzed to determine their antigenicity through Vaxijen server version 2.0. All the HLAⅠ binding epitopes were scanned to determine their immunogenic potential through the Immune Epitope Database(IEDB). All the predicted epitopes of our study were fed to IEDB database to determine whether they had been tested earlier. Results: Twenty two HLA class Ⅱ epitopes and eight HLA classⅠepitopes were predicted. The promiscuous epitopes WMNMEVKII at position 486–494 and VRRLNAVLL at 331–339 were found to bind with 37 and 36 of the 51 HLA class Ⅱ alleles respectively. Epitope MANRSRYQS at position 58–66 and epitopes YQSRKVENM at positions 64–72 were predicted to bind with 12 and 9 HLAⅠI alleles with antigenicity scores of 0.754 9 and 1.013 0 respectively. Epitope YSPPINVRL was predicted to bind 18 HLAⅠ alleles and its antigenicity score was 1.425 9 and immunogenicity score was 0.173 83. This epitope is very useful in the preparation of a universal vaccine against CHIKV infection. Conclusions: Epitopes reported in this study showed promiscuity, antigenicity as well as good binding affinity for the HLA classes. These epitopes will provide the baseline for development of efficacious vaccine for CHIKV.展开更多
Hydroxyapatite (HA) is a synthetic ceramic which is used in numerous biomedical applications. However, its use is restricted in load bearing applications. A novel batch hydrothermal method is indigenously developed to...Hydroxyapatite (HA) is a synthetic ceramic which is used in numerous biomedical applications. However, its use is restricted in load bearing applications. A novel batch hydrothermal method is indigenously developed to synthesize fine size, crystalline hydroxyapatite (HA) and titania doped hydroxyapatite (TiO2-HA) powders with distinct phase formation. Powders were characterized using XRD, FTIR and DSC-TGA. Sharp peaks in HA XRD pattern after sintering at 1000°C indicate significant crystallinity while sharp peaks in TiO2 XRD pattern at 27°, 36° and 5° after sintering indicate anatase to rutile transformation. This fact is also confirmed by FTIR and DSC-TGA Plots.展开更多
Keratin constitutes the major component of the feather,hair,hooves,horns,and wool represents a group of biological material having high cysteine content(7–13%)as compared to other structural proteins.Keratin-based bi...Keratin constitutes the major component of the feather,hair,hooves,horns,and wool represents a group of biological material having high cysteine content(7–13%)as compared to other structural proteins.Keratin-based biomaterials have been investigated extensively over the past few decades due to their intrinsic biological properties and excellent biocompatibility.Unlike other natural polymers such as starch,collagen,chitosan,the complex three-dimensional structure of keratin requires the use of harsh chemical conditions for their dissolution and extraction.The most commonly used methods for keratin extraction are oxidation,reduction,steam explosion,microbial method,microwave irradiation and use of ionic liquids.Keratin-based materials have been used extensively for various biomedical applications such as drug delivery,wound healing,tissue engineering.This review covers the structure,properties,history of keratin research,methods of extraction and some recent advancements related to the use of keratin derived biomaterials in the form of a 3-D scaffold,films,fibers,and hydrogels.展开更多
Cobalt （Co）-doped Bi0.9La0.lFeO3 multiferroics were synthesized by a sol-gel method based on the auto- combustion technique. As-synthesized powder was examined using various characterization techniques to explore th...Cobalt （Co）-doped Bi0.9La0.lFeO3 multiferroics were synthesized by a sol-gel method based on the auto- combustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi0.9La0.1FeO3. X-ray diffraction reveals that Co-doped Bi0.9La0.1FeO3 preserves the perovskite-type rhombohedral structure of BiFeO3, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi2Fe409 has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. Magnetic measurements show the enhancement in magnetization with the increase in Co content.展开更多
Single-phase Zn_(0.95)Co_(0.05)O and Zn_(0.90)Co_(0.05)Al_(0.05)O samples were prepared by a novel combustion method.Xray diffraction studies exhibit the pure phase wurtzite structure of doped ZnO.Energy dispersive x-...Single-phase Zn_(0.95)Co_(0.05)O and Zn_(0.90)Co_(0.05)Al_(0.05)O samples were prepared by a novel combustion method.Xray diffraction studies exhibit the pure phase wurtzite structure of doped ZnO.Energy dispersive x-ray analysis confirms the incorporation of dopants into the host material.Scanning electron microscopy shows the ordered morphology in both of the samples.Temperature-dependent resistivity analysis describes the expected semiconducting behavior that is similar to the parent ZnO materials.Room-temperature magnetic measurements reveal the absence of ferromagnetism in Co-doped ZnO,while the Co and Al co-doped sample displays apparent room-temperature ferromagnetic behavior.The decrease of resistivity and presence of ferromagnetic behavior in Al-doped ZnCoO system corroborate the significant role of free carriers.展开更多
This work aimed to synthesis a novel material that would be able to efficiently remove both organic and microbiological pollutants from wastewater. Through the hydrothermal process, we first doped titanium dioxide, a ...This work aimed to synthesis a novel material that would be able to efficiently remove both organic and microbiological pollutants from wastewater. Through the hydrothermal process, we first doped titanium dioxide, a semiconductor possessing excellent photocatalytic properties with silver nanoparticles having good antibacterial properties. The obtained material was then associated with clay known for its good adsorbent properties to form [AgTiO<sub>2</sub>]:[clay] type nanocomposites. The different mass composition of [AgTiO<sub>2</sub>]:[clay] considered in this work were 1:1;1:0.5;1:0.1;1:0.05 and 1:0.01. The prepared nanocomposites were characterized by means of XRD, FTIR and SEM techniques. Results revealed the presence of TiO<sub>2</sub> anatase and Ag on the surface of the clay mainly composed of kaolinite and quartz. The photocatalytic activities of the nanocomposites were tested in the presence of synthetic Orange II (25 mg/L) wastewater under visible light irradiation. The experiments demonstrated that organic pollutants were effectively photodegraded when the proportion of clay in the mixture (AgTiO<sub>2</sub>)-(Clay) was inferior or equaled to 50%. The use of commercial TiO<sub>2</sub>, for comparison purpose, showed a lower degradation efficiency of the Orange II solution (η < 30%). The antibacterial properties of the nanocomposites [AgTiO<sub>2</sub>]:[clay] were also assessed in the presence of two types of bacteria E. coli (Gram negative) and S. aureus (Gram positive). The antibacterial activities of the nanocomposites were characterized with and without UV irradiation. In dark conditions, the antibacterial activities of nanocomposites (AgTiO<sub>2</sub>)-(Clay) against S. aureus gradually increased with increasing the clay amount. Under visible light irradiation, the nanocomposites showed a significant antimicrobial activity against E. coli and S. aureus.展开更多
Recent advances in the research on the molecular mechanism of cell death and methods for preparation of nanomaterials make the integration of various therapeutic approaches, targeting, and imaging modes into a single ...Recent advances in the research on the molecular mechanism of cell death and methods for preparation of nanomaterials make the integration of various therapeutic approaches, targeting, and imaging modes into a single nanoscale complex a new trend for the development of future nanotherapeutics. Hence, a novel ellipsoidal composite nanoplatform composed of a magnetic Fe3O4/Fe nanorod core （-120 nm） enwrapped by a catalase （CAT）-imprinted fibrous SiO2/ polydopamine （F-SiO2/PDA） shell with thickness 70 nm was prepared in this work. In vitro experiments showed that the Fe3O4/Fe@F-SiO2/PDA nanoparticles can selectively inhibit the bioactivity of CAT in tumor cells by the molecular imprinting technique. As a result, the H2O2 level in tumor cells was elevated dramatically. At the same time, the Fe304FFe core released Fe ions to catalyze the conversion of H2O2 to ＊OH in tumor cells. Eventually, the concentration of ＊OH in tumor cells rapidly rose to a lethal level thus triggering apoptosis. Combined with the remarkable near-infrared light （NIR） photothermal effect of the CAT- imprinted PDA layer, the Fe3O4/Fe@F-SiO2/PDA nanoparticles can effectively kill MCF-7, HeLa, and 293T tumor cells but are not toxic to nontumor cells. Furthermore, these nanoparticles show good capacity for magnetic targeting and suitability for magnetic resonance imaging （MRI）. Therefore, the integrated multifunctional nanoplatform opens up new possibilities for high-efficiency visual targeted nonchemo therapy for cancer.展开更多
Dy2O3 is a rare earth oxide having a number of advanced applications in various fields including protective or antireflective coatings,Main objective of this novel research work is to check the effect of Cr and Cu add...Dy2O3 is a rare earth oxide having a number of advanced applications in various fields including protective or antireflective coatings,Main objective of this novel research work is to check the effect of Cr and Cu addition on different properties of Dy2O3 and achievement of antireflective thin films with enhanced abso rption.Thin films of these materials we re deposited using DC magnetron with reactive cosputtering.XRD studies reveals the crystalline nature of thin films having Dy2O3(222)reflection in all samples with Cr2O3(116)and CuO(111)reflections in Cr and Cu containing compositions.Field emission scanning electron microscopy demonstrates the homogeneous deposition of thin films with uniform shape,size and distribution of grains.Refractive index,extinction coefficient and absorption coefficient significantly increase while optical reflectance decreases with Cr and Cu mediation corroborating an improved antireflective mechanism.The imaginary part of dielectric constant is found to increase slightly with low tangent loss for Cr containing composition co nsidered favorable for energy storage applications.展开更多
A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the "A2+BB2' " approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular struct...A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the "A2+BB2' " approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form the crosslinked HAPTZ-PU film in different ratio of HAPTZ to PEG-IPDI.The glass transition temperature of HAPTZ-PU increased from 44.9 to 56.4 ℃ as the HPUTZ content increased from 20% to 33% from the DSC analysis.The DMA results indicated that the HPUTZ-PU with 20% HPUTZ possessed the highest storage modulus and loss tangent.However,the storage modulus increased with the increasing of HPUTZ segment at higher temperature.The shape memory study showed that all the films presented the excellent shape memory function.Over 98% shape recovery could be obtained for the HAPTZ-PU with 20%-33% HAPTZ segment content within 60 s in the tension deformation test and within 40 s at 80 ℃ in the bend deformation test.展开更多
基金Supported by Higher Education Commission(HEC)of Pakistan.
文摘Zn0.95Ni0.05O and Zn0.90Ni0.05Al0.05O compositions of nanocrystallites are synthesised using the well recognised auto-combustion technique.The x-ray diffraction patterns demonstrate the phase pure characteristic wurtzite-type crystal structure with space group P63mc in both the compositions.The elemental incorporation of Ni and Al contents into the ZnO structure is confirmed by energy dispersive x-ray analysis.The micrographs of scanning electron microscopy show an approximate ordered morphology.The electrical resistivity is observed to decrease with the rising temperature,depicting the characteristic semiconductor behaviour of the samples.The lower values of resistivity and ferromagnetic interactions in the Al-doped sample correspond to an increase of carrier's density.It is observed that the carrier mediated mechanism is mainly responsible for ferromagnetism in ZnO-based diluted magnetic semiconductors.
文摘The substitution of divalent cations of alkaline-earth elements in nanodimensional structures of rare-earth manganites produces advanced materials with potential electrical and magnetic functionalities.A systematic investigation of La_(0.65)A_(0.35)MnO_(3)(A=Ca,Sr,Ba)materials synthesized with a modified citrate route adopting ethanol dehydration has been undertaken.The structural and morphological analyses are carried out by using x-ray diffraction and scanning electron microscopy,respectively.Resistivity measurements are performed in variation with temperature to study the electrical transport properties which are found to vary with the size of the A-site cationic radius.Room temperature magnetic measurements are carried out to investigate the type of magnetic phase present in materials.The stability of the magnetic phase and coercivity are found to be dependent on the size of nanocrystallites.
文摘Objective: To explore RNA dependent RNA polymerase of Chikungunya virus(CHIKV) and develop T cell based epitopes with high antigenicity and good binding affinity for the human leukocyte antigen(HLA) classes as targets for epitopes based CHIKV vaccine. Methods: In this study we downloaded 371 non-structural protein 4 protein sequences of CHIKV belonging to different regions of the world from the US National Institute of Allergy and Infectious Diseases(NIAID) virus pathogen resource database. All the sequences were aligned by using CLUSTALW software and a consensus sequence was developed by using Uni Pro U Gene Software version 1.2.1. PropredⅠand Propred software were used to predict HLAⅠ and HLAⅡ binding promiscuous epitopes from the consensus sequence of non-structural protein 4 protein. The predicted epitopes were analyzed to determine their antigenicity through Vaxijen server version 2.0. All the HLAⅠ binding epitopes were scanned to determine their immunogenic potential through the Immune Epitope Database(IEDB). All the predicted epitopes of our study were fed to IEDB database to determine whether they had been tested earlier. Results: Twenty two HLA class Ⅱ epitopes and eight HLA classⅠepitopes were predicted. The promiscuous epitopes WMNMEVKII at position 486–494 and VRRLNAVLL at 331–339 were found to bind with 37 and 36 of the 51 HLA class Ⅱ alleles respectively. Epitope MANRSRYQS at position 58–66 and epitopes YQSRKVENM at positions 64–72 were predicted to bind with 12 and 9 HLAⅠI alleles with antigenicity scores of 0.754 9 and 1.013 0 respectively. Epitope YSPPINVRL was predicted to bind 18 HLAⅠ alleles and its antigenicity score was 1.425 9 and immunogenicity score was 0.173 83. This epitope is very useful in the preparation of a universal vaccine against CHIKV infection. Conclusions: Epitopes reported in this study showed promiscuity, antigenicity as well as good binding affinity for the HLA classes. These epitopes will provide the baseline for development of efficacious vaccine for CHIKV.
文摘Hydroxyapatite (HA) is a synthetic ceramic which is used in numerous biomedical applications. However, its use is restricted in load bearing applications. A novel batch hydrothermal method is indigenously developed to synthesize fine size, crystalline hydroxyapatite (HA) and titania doped hydroxyapatite (TiO2-HA) powders with distinct phase formation. Powders were characterized using XRD, FTIR and DSC-TGA. Sharp peaks in HA XRD pattern after sintering at 1000°C indicate significant crystallinity while sharp peaks in TiO2 XRD pattern at 27°, 36° and 5° after sintering indicate anatase to rutile transformation. This fact is also confirmed by FTIR and DSC-TGA Plots.
基金supported by Department of Anatomy,University of Otago,Otago,9016,New Zealand.
文摘Keratin constitutes the major component of the feather,hair,hooves,horns,and wool represents a group of biological material having high cysteine content(7–13%)as compared to other structural proteins.Keratin-based biomaterials have been investigated extensively over the past few decades due to their intrinsic biological properties and excellent biocompatibility.Unlike other natural polymers such as starch,collagen,chitosan,the complex three-dimensional structure of keratin requires the use of harsh chemical conditions for their dissolution and extraction.The most commonly used methods for keratin extraction are oxidation,reduction,steam explosion,microbial method,microwave irradiation and use of ionic liquids.Keratin-based materials have been used extensively for various biomedical applications such as drug delivery,wound healing,tissue engineering.This review covers the structure,properties,history of keratin research,methods of extraction and some recent advancements related to the use of keratin derived biomaterials in the form of a 3-D scaffold,films,fibers,and hydrogels.
文摘Cobalt （Co）-doped Bi0.9La0.lFeO3 multiferroics were synthesized by a sol-gel method based on the auto- combustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi0.9La0.1FeO3. X-ray diffraction reveals that Co-doped Bi0.9La0.1FeO3 preserves the perovskite-type rhombohedral structure of BiFeO3, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi2Fe409 has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. Magnetic measurements show the enhancement in magnetization with the increase in Co content.
基金by the Higher Education Commission(HEC)of Pakistan under the indigenous Ph.D.fellowship 5000 Scheme.
文摘Single-phase Zn_(0.95)Co_(0.05)O and Zn_(0.90)Co_(0.05)Al_(0.05)O samples were prepared by a novel combustion method.Xray diffraction studies exhibit the pure phase wurtzite structure of doped ZnO.Energy dispersive x-ray analysis confirms the incorporation of dopants into the host material.Scanning electron microscopy shows the ordered morphology in both of the samples.Temperature-dependent resistivity analysis describes the expected semiconducting behavior that is similar to the parent ZnO materials.Room-temperature magnetic measurements reveal the absence of ferromagnetism in Co-doped ZnO,while the Co and Al co-doped sample displays apparent room-temperature ferromagnetic behavior.The decrease of resistivity and presence of ferromagnetic behavior in Al-doped ZnCoO system corroborate the significant role of free carriers.
文摘This work aimed to synthesis a novel material that would be able to efficiently remove both organic and microbiological pollutants from wastewater. Through the hydrothermal process, we first doped titanium dioxide, a semiconductor possessing excellent photocatalytic properties with silver nanoparticles having good antibacterial properties. The obtained material was then associated with clay known for its good adsorbent properties to form [AgTiO<sub>2</sub>]:[clay] type nanocomposites. The different mass composition of [AgTiO<sub>2</sub>]:[clay] considered in this work were 1:1;1:0.5;1:0.1;1:0.05 and 1:0.01. The prepared nanocomposites were characterized by means of XRD, FTIR and SEM techniques. Results revealed the presence of TiO<sub>2</sub> anatase and Ag on the surface of the clay mainly composed of kaolinite and quartz. The photocatalytic activities of the nanocomposites were tested in the presence of synthetic Orange II (25 mg/L) wastewater under visible light irradiation. The experiments demonstrated that organic pollutants were effectively photodegraded when the proportion of clay in the mixture (AgTiO<sub>2</sub>)-(Clay) was inferior or equaled to 50%. The use of commercial TiO<sub>2</sub>, for comparison purpose, showed a lower degradation efficiency of the Orange II solution (η < 30%). The antibacterial properties of the nanocomposites [AgTiO<sub>2</sub>]:[clay] were also assessed in the presence of two types of bacteria E. coli (Gram negative) and S. aureus (Gram positive). The antibacterial activities of the nanocomposites were characterized with and without UV irradiation. In dark conditions, the antibacterial activities of nanocomposites (AgTiO<sub>2</sub>)-(Clay) against S. aureus gradually increased with increasing the clay amount. Under visible light irradiation, the nanocomposites showed a significant antimicrobial activity against E. coli and S. aureus.
基金We thank Prof. Zhishen Ge of the Department of Polymer Science and Engineering of USTC, Prof. Yu Zhao of Department of Plastic Surgery, The First Affiliated Hospital of Anhui Medical University, and Prof. Yinfeng Qian of Department of Radiology, The First Affiliated Hospital of Anhui Medical University for their kind help in providing the 808 nm semicon- ductor laser device, adipose-derived stem cells, and the instruction of MRI testing, respectively. This work was supported by the National Natural Science Foundation of China （Nos. 51103143, 51173175, 51473152, and 51573174）, the Fundamental Research Funds for the Central Universities （Nos. WK2060200012 and WK3450000001）.
文摘Recent advances in the research on the molecular mechanism of cell death and methods for preparation of nanomaterials make the integration of various therapeutic approaches, targeting, and imaging modes into a single nanoscale complex a new trend for the development of future nanotherapeutics. Hence, a novel ellipsoidal composite nanoplatform composed of a magnetic Fe3O4/Fe nanorod core （-120 nm） enwrapped by a catalase （CAT）-imprinted fibrous SiO2/ polydopamine （F-SiO2/PDA） shell with thickness 70 nm was prepared in this work. In vitro experiments showed that the Fe3O4/Fe@F-SiO2/PDA nanoparticles can selectively inhibit the bioactivity of CAT in tumor cells by the molecular imprinting technique. As a result, the H2O2 level in tumor cells was elevated dramatically. At the same time, the Fe304FFe core released Fe ions to catalyze the conversion of H2O2 to ＊OH in tumor cells. Eventually, the concentration of ＊OH in tumor cells rapidly rose to a lethal level thus triggering apoptosis. Combined with the remarkable near-infrared light （NIR） photothermal effect of the CAT- imprinted PDA layer, the Fe3O4/Fe@F-SiO2/PDA nanoparticles can effectively kill MCF-7, HeLa, and 293T tumor cells but are not toxic to nontumor cells. Furthermore, these nanoparticles show good capacity for magnetic targeting and suitability for magnetic resonance imaging （MRI）. Therefore, the integrated multifunctional nanoplatform opens up new possibilities for high-efficiency visual targeted nonchemo therapy for cancer.
基金the Deanship of Scientific Research at King Saud University for funding under Research Group(No.RG 1435-004)
文摘Dy2O3 is a rare earth oxide having a number of advanced applications in various fields including protective or antireflective coatings,Main objective of this novel research work is to check the effect of Cr and Cu addition on different properties of Dy2O3 and achievement of antireflective thin films with enhanced abso rption.Thin films of these materials we re deposited using DC magnetron with reactive cosputtering.XRD studies reveals the crystalline nature of thin films having Dy2O3(222)reflection in all samples with Cr2O3(116)and CuO(111)reflections in Cr and Cu containing compositions.Field emission scanning electron microscopy demonstrates the homogeneous deposition of thin films with uniform shape,size and distribution of grains.Refractive index,extinction coefficient and absorption coefficient significantly increase while optical reflectance decreases with Cr and Cu mediation corroborating an improved antireflective mechanism.The imaginary part of dielectric constant is found to increase slightly with low tangent loss for Cr containing composition co nsidered favorable for energy storage applications.
基金support of the National Natural Science Foundation of China (50633010) is gratefully acknowledged
文摘A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the "A2+BB2' " approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form the crosslinked HAPTZ-PU film in different ratio of HAPTZ to PEG-IPDI.The glass transition temperature of HAPTZ-PU increased from 44.9 to 56.4 ℃ as the HPUTZ content increased from 20% to 33% from the DSC analysis.The DMA results indicated that the HPUTZ-PU with 20% HPUTZ possessed the highest storage modulus and loss tangent.However,the storage modulus increased with the increasing of HPUTZ segment at higher temperature.The shape memory study showed that all the films presented the excellent shape memory function.Over 98% shape recovery could be obtained for the HAPTZ-PU with 20%-33% HAPTZ segment content within 60 s in the tension deformation test and within 40 s at 80 ℃ in the bend deformation test.
