It is very important to understand why a small amount of alkali metal doping in Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells can improve the conversion efficiency.In this work,Na-doped CZTSSe is prepared by a simple soluti...It is very important to understand why a small amount of alkali metal doping in Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells can improve the conversion efficiency.In this work,Na-doped CZTSSe is prepared by a simple solution method,and then the effects on the surface properties of the absorber layer,the buffer layer growth,and the modifications of the solar cell performance induced by the Na doping are studied.The surface of the absorber layer is more Cu-depletion and less roughness due to the Na doping.In addition,the contact angle of the surface increases because of Na doping.As a consequence,the thickness of the CdS buffer layer is significantly reduced and the optical losses in the CdS buffer layer are decreased.The difference of quasi-Fermi levels(EFn-EFp) increases with a small amount of Na doping in the CZTSSe solar cell,so that open circuit voltage(VOC) increased significantly.This work offers new insights into the effects of Na doping on CZTSSe via a solution-based approach and provides a deeper understanding of the origin of the efficiency improvement of Na-doped CZTSSe thin film solar cells.展开更多
Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (s...Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (sudden death) of prolonged strenuous exercise. Animal experiments would be helpful to resolve this problem. The objective of this study was to obtain baseline data of two new indicators of cardiac reserve in rats, rabbits, and dogs. Methods: Ten New Zealand White rabbits (1. 5 to 2 kg, 4 females), 10 male Wistar rats (2 months old), and 10 Golden Retriever dogs (40 days old, 5 females) were included in this study. Phonocardiogram of each animal was recorded. The basic points concerning heart sound quantitative analysis were: 1) measuring the duration and the amplitude of relevant heart sound components;2) calculating and analyzing relevant indicators based on the data obtained from the above measurements, including the ratio of diastolic to systolic duration (D/S) and the ratio of the amplitude of the first heart sound to the amplitude of the second heart sound (S1/S2). Results: The baseline data of D/S ratio and S1/S2 ratio in rats, rabbits, and dogs were obtained. The swimming time to exhaustion for rabbits was several to a dozen minutes, and for rats, several hours. Conclusion: D/S ratio has an important biological implication, which is a safe and easy indicator for evaluating the cardiac health status of both animals and humans.展开更多
In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptano...In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in high yields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer were investigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles, pseudoplasticity of these solutions and the effect of the presence of surfactant. These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.展开更多
One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for ...One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wutzite phase （hexagonal structure）. SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods （sulfur precursor： Na2S） was shown blue shift to 485 nm due to the quantum size effect.展开更多
A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence...A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence （CL） system. The effects of some critical experimental conditions were discussed and the optimization of working conditions was investigated. The linear dynamic range is 3.00 × 10^-8 - 9.00 × 10^-7 mol ·L-1 and the detection limit for CPLX is 4.40 × 10^-9 mol·L^-1. This method was applied to the determination of CPLX in tablet, urine, and serum samples and the recoveries of real sample analyses were in the range from 110 ± 4 to 104 ± 4.展开更多
This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The ...This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The field soil contained concentrations of Pb (307.31 mg⋅kg−1), Zn (207.77 mg⋅kg−1) and Cr (447.50 mg⋅kg−1). Both (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water were found to be effective on removing (Na2S2O5) Pb, Cr and Zn respectively. (Na2S2O5) + (0.1 HCl) Cr, Zn and Pb respectively. Sulfur Pb, Cr and Zn respectively. The removal rate of Pb, Zn, and Cr varied from 10.35% - 26%, 3.4% - 21.60% and 4.97% - 23.88% for (0.01 M Na2S2O5 respectively. The removal rate of Pb, Zn, and Cr varied from 16.13% - 20.07%, 8.20% - 23.48%, 5.42% - 28.93% for (0.01 M Na2S2O5 + 0.1 M HCl) respectively. The removal rate of Pb, Zn, and Cr varied from 10.20% - 25.5%, 9.55% - 25.13% and 6.04% - 25.54% for (S) respectively.展开更多
基金supported by the National Key R&D Program of China(2019YFB1503500,2018YFB1500200,2018YEE0203400)the Natural Science Foundation of China(U1902218,11774187)the 111 project(B16027)。
文摘It is very important to understand why a small amount of alkali metal doping in Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells can improve the conversion efficiency.In this work,Na-doped CZTSSe is prepared by a simple solution method,and then the effects on the surface properties of the absorber layer,the buffer layer growth,and the modifications of the solar cell performance induced by the Na doping are studied.The surface of the absorber layer is more Cu-depletion and less roughness due to the Na doping.In addition,the contact angle of the surface increases because of Na doping.As a consequence,the thickness of the CdS buffer layer is significantly reduced and the optical losses in the CdS buffer layer are decreased.The difference of quasi-Fermi levels(EFn-EFp) increases with a small amount of Na doping in the CZTSSe solar cell,so that open circuit voltage(VOC) increased significantly.This work offers new insights into the effects of Na doping on CZTSSe via a solution-based approach and provides a deeper understanding of the origin of the efficiency improvement of Na-doped CZTSSe thin film solar cells.
文摘Background: It is difficult to observe the phenomena of cardiac fatigue under a low or moderate workload test, and little was reported about cardiac fatigue under a heavy workload test because of the potential risk (sudden death) of prolonged strenuous exercise. Animal experiments would be helpful to resolve this problem. The objective of this study was to obtain baseline data of two new indicators of cardiac reserve in rats, rabbits, and dogs. Methods: Ten New Zealand White rabbits (1. 5 to 2 kg, 4 females), 10 male Wistar rats (2 months old), and 10 Golden Retriever dogs (40 days old, 5 females) were included in this study. Phonocardiogram of each animal was recorded. The basic points concerning heart sound quantitative analysis were: 1) measuring the duration and the amplitude of relevant heart sound components;2) calculating and analyzing relevant indicators based on the data obtained from the above measurements, including the ratio of diastolic to systolic duration (D/S) and the ratio of the amplitude of the first heart sound to the amplitude of the second heart sound (S1/S2). Results: The baseline data of D/S ratio and S1/S2 ratio in rats, rabbits, and dogs were obtained. The swimming time to exhaustion for rabbits was several to a dozen minutes, and for rats, several hours. Conclusion: D/S ratio has an important biological implication, which is a safe and easy indicator for evaluating the cardiac health status of both animals and humans.
基金Project supported by National Natural Science Foundation,Grant approval numbers 29472074 and 29632003
文摘In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in high yields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer were investigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles, pseudoplasticity of these solutions and the effect of the presence of surfactant. These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.
文摘One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wutzite phase （hexagonal structure）. SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods （sulfur precursor： Na2S） was shown blue shift to 485 nm due to the quantum size effect.
文摘A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence （CL） system. The effects of some critical experimental conditions were discussed and the optimization of working conditions was investigated. The linear dynamic range is 3.00 × 10^-8 - 9.00 × 10^-7 mol ·L-1 and the detection limit for CPLX is 4.40 × 10^-9 mol·L^-1. This method was applied to the determination of CPLX in tablet, urine, and serum samples and the recoveries of real sample analyses were in the range from 110 ± 4 to 104 ± 4.
文摘This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The field soil contained concentrations of Pb (307.31 mg⋅kg−1), Zn (207.77 mg⋅kg−1) and Cr (447.50 mg⋅kg−1). Both (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water were found to be effective on removing (Na2S2O5) Pb, Cr and Zn respectively. (Na2S2O5) + (0.1 HCl) Cr, Zn and Pb respectively. Sulfur Pb, Cr and Zn respectively. The removal rate of Pb, Zn, and Cr varied from 10.35% - 26%, 3.4% - 21.60% and 4.97% - 23.88% for (0.01 M Na2S2O5 respectively. The removal rate of Pb, Zn, and Cr varied from 16.13% - 20.07%, 8.20% - 23.48%, 5.42% - 28.93% for (0.01 M Na2S2O5 + 0.1 M HCl) respectively. The removal rate of Pb, Zn, and Cr varied from 10.20% - 25.5%, 9.55% - 25.13% and 6.04% - 25.54% for (S) respectively.
