The performance of dye-sensitized solar cells （DSSCs） is strongly affected by the properties of semiconductor nanoparticles. In this work, we used TiO2 particles prepared by TiC14 hydrolysis n times on A1203 films ...The performance of dye-sensitized solar cells （DSSCs） is strongly affected by the properties of semiconductor nanoparticles. In this work, we used TiO2 particles prepared by TiC14 hydrolysis n times on A1203 films （A/T（n））, and investigated morphology, photoelectric, and electron transport properties of A/T（n）. The TiO2 shell was composed of 10-20 nm nanoparticles and the number of nanoparticles increased with increasing TIC14 treatment times. The highest photoelectric conversion efficiency of 3.23% was obtained as A/T（4）. IMPS results indicated that electron transport rate was high enough to conduct current, and was not the dominating effect to limit the Jsc. Jsc was mainly determined by dye loading on TiO2 and the interconnection of TiO2. These may provide a new strategy for preparing semiconductor working electrodes for DSSC.展开更多
To investigate factors involved in the secretion of protoporphyrin IX (PpIX), a superficial eggshell pigment, from shell gland epithelial cells of Japanese quail, we cultured cells in Ham’s F12 medium with calcium ch...To investigate factors involved in the secretion of protoporphyrin IX (PpIX), a superficial eggshell pigment, from shell gland epithelial cells of Japanese quail, we cultured cells in Ham’s F12 medium with calcium chloride and quail plasma. The addition of hormones (prostaglandin F2α, progesterone, estradiol-17β) to the medium did not change the PpIX concentration in the culture supernatant, but changing the calcium chloride (CaCl2) concentration did: a lower concentration of CaCl2 led to a higher PpIX concentration;0 mM CaCl2 enhanced the secretion of PpIX from epithelial cells prepared at 5 or 7 mM CaCl2. The result suggests that a drop in concentration of CaCl2 mimics the end of shell calcification and stimulates rapid secretion of PpIX in vivo. Bovine serum albumin was almost as effective as quail plasma for PpIX secretion in culture, and would facilitate further study of the mechanism of PpIX secretion.展开更多
To investigate the secretion of protoporphyrin IX (PpIX), superficial eggshell pigment, from shell gland cells of Japanese quail, the epithelial cells of the gland were collected and isolated for cultivation in vitro....To investigate the secretion of protoporphyrin IX (PpIX), superficial eggshell pigment, from shell gland cells of Japanese quail, the epithelial cells of the gland were collected and isolated for cultivation in vitro. An analysis of a peak for PpIX in the cells was performed using a fluorescence microplate reader. The measurement showed that PpIX has a peak of excitation wavelength at 410 nm and emission wavelength at 606 nm in the culture medium (HamF12 + 4% HCl). Volumes of PpIX in the medium after 4 hour culture of the cells were measured with a microplate reader using filter set of excitation wavelength 400/30nm and emission wavelength 620/40nm. However the cells did not secrete significantly PpIX during 4 hour incubation in this culture system, addition of quail plasma to the medium resulted in significantly higher secretion. A cultivation system in this study is able to use for the study on the mechanism of the secretion of eggshell pigment, PpIX from Japanese quail shell gland epithelial cells.展开更多
AIM: To facilitate engineering of suitable biomaterials to meet the challenges associated with myocardial infarction. METHODS: Poly (glycerol sebacate)/collagen (PGS/ collagen) core/shell fibers were fabricated by cor...AIM: To facilitate engineering of suitable biomaterials to meet the challenges associated with myocardial infarction. METHODS: Poly (glycerol sebacate)/collagen (PGS/ collagen) core/shell fibers were fabricated by core/ shell electrospinning technique, with core as PGS and shell as collagen polymer; and the scaffolds were characterized by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), contact angle and tensile testing for cardiac tissue engineering. Collagen nanofibers were also fabricated by electrospinning for comparison with core/shell fibers. Studies on cell-scaffold interaction were carriedout using cardiac cells and mesenchymal stem cells (MSCs) co-culture system with cardiac cells and MSCs separately serving as positive and negative controls respectively. The co-culture system was characterized for cell proliferation and differentiation of MSCs into cardiomyogenic lineage in the co-culture environment using dual immunocytochemistry. The co-culture cells were stained with cardiac specific marker proteins like actinin and troponin and MSC specific marker protein CD 105 for proving the cardiogenic differentiation of MSCs. Further the morphology of cells was analyzed using SEM.RESULTS: PGS/collagen core/shell fibers, core is PGS polymer having an elastic modulus related to that of cardiac fibers and shell as collagen, providing natural environment for cellular activities like cell adhesion, proliferation and differentiation. SEM micrographs of electrospun fibrous scaffolds revealed porous, beadless, uniform fibers with a fiber diameter in the range of 380 ± 77 nm and 1192 ± 277 nm for collagen fibers and PGS/collagen core/shell fibers respectively. The obtained PGS/collagen core/shell fibrous scaffolds were hydrophilic having a water contact angle of 17.9 ± 4.6° compared to collagen nanofibers which had a contact angle value of 30 ± 3.2°. The PGS/collagen core/shell fibers had mechanical properties comparable to that of native heart muscle with a young's modulus of 4.24 ± 0.7 MPa, while that of collagen nanofibers was comparatively higher around 30.11 ± 1.68 MPa. FTIR spectrum was performed to confirm the functional groups present in the electrospun scaffolds. Amide Ⅰ and amide Ⅱ of collagen were detected at 1638.95 cm -1 and 1551.64 cm -1 in the electrospun collagen fibers and at 1646.22 cm -1 and 1540.73 cm -1 for PGS/collagen core/shell fibers respectively. Cell culture studies performed using MSCs and cardiac cells co-culture environment, indicated that the cellproliferation significantly increased on PGS/collagen core/shell scaffolds compared to collagen fibers and the cardiac marker proteins actinin and troponin were expressed more on PGS/collagen core/shell scaffolds compared to collagen fibers alone. Dual immunofluorescent staining was performed to further confirm the cardiogenic differentiation of MSCs by employing MSC specific marker protein, CD 105 and cardiac specific marker protein, actinin. SEM observations of cardiac cells showed normal morphology on PGS/collagen fibers and providing adequate tensile strength for the regeneration of myocardial infarction. CONCLUSION: Combination of PGS/collagen fibers and cardiac cells/MSCs co-culture system providing natural microenvironments to improve cell survival and differentiation, could bring cardiac tissue engineering to clinical application.展开更多
Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection.Recently,a new strategy relying on type-Ⅱ band alignment has been proposed to facili...Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection.Recently,a new strategy relying on type-Ⅱ band alignment has been proposed to facilitate efficient charge separation in core/shell nanowire solar cells.This paper reviews the type-Ⅱ heterojunction solar cells based on core/shell nanowire arrays,and specifically focuses on the progress of theoretical design and fabrication of type-Ⅱ Zn O/Zn Se core/shell nanowire-based solar cells.A strong photoresponse associated with the type-Ⅱ interfacial transition exhibits a threshold of 1.6 e V,which demonstrates the feasibility and great potential for exploring all-inorganic versions of type-Ⅱ heterojunction solar cells using wide bandgap semiconductors.Future prospects in this area are also outlooked.展开更多
The changeable structure of 2 D graphene nanosheets makes the Pt-based nanoparticles（NPs） possess a low efficiency toward oxygen reduction reaction（ORR） and a short lifetime for proton exchange membrane fuel cells...The changeable structure of 2 D graphene nanosheets makes the Pt-based nanoparticles（NPs） possess a low efficiency toward oxygen reduction reaction（ORR） and a short lifetime for proton exchange membrane fuel cells. Thus, a unique Ti C@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs.The as-prepared Pt/GNS@Ti C catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2 D graphene nanosheets,impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 m V cmunder a low Pt loading(0.25 mg Pt cm) and H/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields.展开更多
Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging...Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging [1,2]. Pt-based catalysts have been acknowledged to be the most effective catalyst for the oxygen reduction reaction(ORR) [3–5]. However, both the source scarcity and high cost of Pt severely hinder the commercial application of the PEMFCs [1,6,7].展开更多
基金Project supported by the National Materials Genome Project of China(Grant No.2016YFB0700600)the National Natural Science Foundation of China(Grant No.51673204)
文摘The performance of dye-sensitized solar cells （DSSCs） is strongly affected by the properties of semiconductor nanoparticles. In this work, we used TiO2 particles prepared by TiC14 hydrolysis n times on A1203 films （A/T（n））, and investigated morphology, photoelectric, and electron transport properties of A/T（n）. The TiO2 shell was composed of 10-20 nm nanoparticles and the number of nanoparticles increased with increasing TIC14 treatment times. The highest photoelectric conversion efficiency of 3.23% was obtained as A/T（4）. IMPS results indicated that electron transport rate was high enough to conduct current, and was not the dominating effect to limit the Jsc. Jsc was mainly determined by dye loading on TiO2 and the interconnection of TiO2. These may provide a new strategy for preparing semiconductor working electrodes for DSSC.
文摘To investigate factors involved in the secretion of protoporphyrin IX (PpIX), a superficial eggshell pigment, from shell gland epithelial cells of Japanese quail, we cultured cells in Ham’s F12 medium with calcium chloride and quail plasma. The addition of hormones (prostaglandin F2α, progesterone, estradiol-17β) to the medium did not change the PpIX concentration in the culture supernatant, but changing the calcium chloride (CaCl2) concentration did: a lower concentration of CaCl2 led to a higher PpIX concentration;0 mM CaCl2 enhanced the secretion of PpIX from epithelial cells prepared at 5 or 7 mM CaCl2. The result suggests that a drop in concentration of CaCl2 mimics the end of shell calcification and stimulates rapid secretion of PpIX in vivo. Bovine serum albumin was almost as effective as quail plasma for PpIX secretion in culture, and would facilitate further study of the mechanism of PpIX secretion.
文摘To investigate the secretion of protoporphyrin IX (PpIX), superficial eggshell pigment, from shell gland cells of Japanese quail, the epithelial cells of the gland were collected and isolated for cultivation in vitro. An analysis of a peak for PpIX in the cells was performed using a fluorescence microplate reader. The measurement showed that PpIX has a peak of excitation wavelength at 410 nm and emission wavelength at 606 nm in the culture medium (HamF12 + 4% HCl). Volumes of PpIX in the medium after 4 hour culture of the cells were measured with a microplate reader using filter set of excitation wavelength 400/30nm and emission wavelength 620/40nm. However the cells did not secrete significantly PpIX during 4 hour incubation in this culture system, addition of quail plasma to the medium resulted in significantly higher secretion. A cultivation system in this study is able to use for the study on the mechanism of the secretion of eggshell pigment, PpIX from Japanese quail shell gland epithelial cells.
基金Supported by NRF-Technion, No. R-398-001-065-592Ministry of Education, No. R-265-000-318-112NUSNNI, National University of Singapore
文摘AIM: To facilitate engineering of suitable biomaterials to meet the challenges associated with myocardial infarction. METHODS: Poly (glycerol sebacate)/collagen (PGS/ collagen) core/shell fibers were fabricated by core/ shell electrospinning technique, with core as PGS and shell as collagen polymer; and the scaffolds were characterized by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), contact angle and tensile testing for cardiac tissue engineering. Collagen nanofibers were also fabricated by electrospinning for comparison with core/shell fibers. Studies on cell-scaffold interaction were carriedout using cardiac cells and mesenchymal stem cells (MSCs) co-culture system with cardiac cells and MSCs separately serving as positive and negative controls respectively. The co-culture system was characterized for cell proliferation and differentiation of MSCs into cardiomyogenic lineage in the co-culture environment using dual immunocytochemistry. The co-culture cells were stained with cardiac specific marker proteins like actinin and troponin and MSC specific marker protein CD 105 for proving the cardiogenic differentiation of MSCs. Further the morphology of cells was analyzed using SEM.RESULTS: PGS/collagen core/shell fibers, core is PGS polymer having an elastic modulus related to that of cardiac fibers and shell as collagen, providing natural environment for cellular activities like cell adhesion, proliferation and differentiation. SEM micrographs of electrospun fibrous scaffolds revealed porous, beadless, uniform fibers with a fiber diameter in the range of 380 ± 77 nm and 1192 ± 277 nm for collagen fibers and PGS/collagen core/shell fibers respectively. The obtained PGS/collagen core/shell fibrous scaffolds were hydrophilic having a water contact angle of 17.9 ± 4.6° compared to collagen nanofibers which had a contact angle value of 30 ± 3.2°. The PGS/collagen core/shell fibers had mechanical properties comparable to that of native heart muscle with a young's modulus of 4.24 ± 0.7 MPa, while that of collagen nanofibers was comparatively higher around 30.11 ± 1.68 MPa. FTIR spectrum was performed to confirm the functional groups present in the electrospun scaffolds. Amide Ⅰ and amide Ⅱ of collagen were detected at 1638.95 cm -1 and 1551.64 cm -1 in the electrospun collagen fibers and at 1646.22 cm -1 and 1540.73 cm -1 for PGS/collagen core/shell fibers respectively. Cell culture studies performed using MSCs and cardiac cells co-culture environment, indicated that the cellproliferation significantly increased on PGS/collagen core/shell scaffolds compared to collagen fibers and the cardiac marker proteins actinin and troponin were expressed more on PGS/collagen core/shell scaffolds compared to collagen fibers alone. Dual immunofluorescent staining was performed to further confirm the cardiogenic differentiation of MSCs by employing MSC specific marker protein, CD 105 and cardiac specific marker protein, actinin. SEM observations of cardiac cells showed normal morphology on PGS/collagen fibers and providing adequate tensile strength for the regeneration of myocardial infarction. CONCLUSION: Combination of PGS/collagen fibers and cardiac cells/MSCs co-culture system providing natural microenvironments to improve cell survival and differentiation, could bring cardiac tissue engineering to clinical application.
基金supported by "973" Program (No.2012CB619301 and 2011CB925600)the National Natural Science Foundations of China (No.61227009,61106008,61106118,90921002,and 60827004)+1 种基金the Natural Science Foundations of Fujian Provincethe fundamental research funds for the central universities (No.2011121042 and 2011121026)
文摘Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection.Recently,a new strategy relying on type-Ⅱ band alignment has been proposed to facilitate efficient charge separation in core/shell nanowire solar cells.This paper reviews the type-Ⅱ heterojunction solar cells based on core/shell nanowire arrays,and specifically focuses on the progress of theoretical design and fabrication of type-Ⅱ Zn O/Zn Se core/shell nanowire-based solar cells.A strong photoresponse associated with the type-Ⅱ interfacial transition exhibits a threshold of 1.6 e V,which demonstrates the feasibility and great potential for exploring all-inorganic versions of type-Ⅱ heterojunction solar cells using wide bandgap semiconductors.Future prospects in this area are also outlooked.
基金supported by the National Science Foundation of China(nos.51372186 and 51672204)
文摘The changeable structure of 2 D graphene nanosheets makes the Pt-based nanoparticles（NPs） possess a low efficiency toward oxygen reduction reaction（ORR） and a short lifetime for proton exchange membrane fuel cells. Thus, a unique Ti C@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs.The as-prepared Pt/GNS@Ti C catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2 D graphene nanosheets,impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 m V cmunder a low Pt loading(0.25 mg Pt cm) and H/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields.
基金supported by the National Natural Science Foundation of China (Nos. 21676106 and 21576101)Science and Technology Program of Guangzhou (201704030065)+1 种基金Science and Technology Program of Guangdong (2017A050506015)the Fundamental Research Funds for the Central Universities
文摘Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging [1,2]. Pt-based catalysts have been acknowledged to be the most effective catalyst for the oxygen reduction reaction(ORR) [3–5]. However, both the source scarcity and high cost of Pt severely hinder the commercial application of the PEMFCs [1,6,7].
