Background：Quantifying syphilis prevalence is important for planning interventions and advocating for resources on syphilis.However,data on large sample studies regarding the prevalence of syphilis among reproductive...Background：Quantifying syphilis prevalence is important for planning interventions and advocating for resources on syphilis.However,data on large sample studies regarding the prevalence of syphilis among reproductive-age women in rural China were not available for analysis.The aim of the study was to determine the prevalence,epidemiological characteristics,and related factors of syphilis infection among reproductive-age women in rural China.Methods：Data were obtained from a nationwide,population-based,cross-sectional study under the National Free Preconception Health Examination Project which covered all the 31 provinces in China's Mainland.Women intending to get pregnant within the next 6 months were enrolled between January 1,2010,and December 31,2012.Sociodemographic,gynecological and obstetric characteristics,and other relevant information were obtained through face-to-face interviews.Treponema pallidum particle agglutination assay test was used to detect positive samples of syphilis.Univariate and multivariate logistic regressions were performed to assess the associations between syphilis seropositivity and related factors.Results：The overall seroprevalence of syphilis （SPS） among the 2,044,126 women who received syphilis screening test during 2010-2012 was 0.37% （95% confidence interval [CI]：0.36-0.37%）.The SPS appeared 0.24% （95% CI：0.23-0.26%） and 0.66% （95% CI：0.59-0.72%） in women at 21-24 and 40-44 years of age,respectively,showing an increase of SPS,parallel with age,and the difference was significant.SPS was significantly higher in ethnic minorities than that in Han nationality （0.58% vs.0.35%,respectively,odds ratio [OR] =1.41,95% CI：1.30-1.53） and higher in workers than that in farmers （0.45% vs.0.36%,respectively,OR =1.27,95% CI：1.14-1.41）.Women with primary school or below level had a higher SPS as compared to those with college or above educational level （0.61% vs.0.32%,respectively,OR =2.49,95% CI：2.14-2.89）,and the increase reversely correlated with展开更多
Temperature-dependent and driving current-dependent electroluminescence spectra of two different InGaN/GaN multiple quantum well structures SA and SB are investigated,with the In composition in each well layer(WL)alon...Temperature-dependent and driving current-dependent electroluminescence spectra of two different InGaN/GaN multiple quantum well structures SA and SB are investigated,with the In composition in each well layer(WL)along the growth direction progressively increasing for SA and progressively decreasing for SB.The results show that SB exhibits an improved efficiency droop compared with SA.This phenomenon can be explained as follows:owing to the difference in growth pattern of the WL between these two samples,the terminal region of the WL in SB contains fewer In atoms than in SA,and therefore the former undergoes less In volatilization than the latter during the waiting period required for warming-up due to the difference in the growth temperature between well and barrier layers.This results in SB having a deeper triangular-shaped potential well in its WL than SA,which strongly confines the carriers to the initial region of the WL to prevent them from leaking to the p-GaN side,thus improving the efficiency droop.Moreover,the improvement in the efficiency droop for SB is also partly attributed to its stronger Coulomb screening effect and carrier localization effect.展开更多
Photoluminescence(PL) spectra of two different green InGaN/GaN multiple quantum well(MQW) samples S1 and S2,respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyze...Photoluminescence(PL) spectra of two different green InGaN/GaN multiple quantum well(MQW) samples S1 and S2,respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K-3 30 K and an excitation power range of 0.001 mW-75 mW.The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range,the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples,and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1;in the highest excitation power range,the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1,and by the Coulomb screening effect for S2.The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature,and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatchinduced quantum-confined Stark effect.This explanation is also supported by other relevant measurements of the samples,such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.展开更多
The photoluminescence(PL) properties of blue multiple InGaN/GaN quantum well(BMQW) and green multiple InGaN/GaN quantum well(GMQW) formed on a single sapphire substrate are investigated. The results indicate that the ...The photoluminescence(PL) properties of blue multiple InGaN/GaN quantum well(BMQW) and green multiple InGaN/GaN quantum well(GMQW) formed on a single sapphire substrate are investigated. The results indicate that the peak energy of GMQW-related emission(PG) exhibits more significant "S-shaped" dependence on temperature than that of BMQW-related emission(PB), and the excitation power-dependent carrier-scattering effect is observed only in the PG emission;the excitation power-dependent total blue-shift(narrowing) of peak position(line-width) for the PGemission is more significant than that for the PBemission;the GMQW shows a lower internal quantum efficiency than the BMQW. All of these results can be attributed to the fact that the GMQW has higher indium content than the BMQW due to its lower growth temperature and late growth, and the higher indium content in the GMQW induces a more significant compositional fluctuation, a stronger quantum confined Stark effect, and more non-radiative centers.展开更多
文摘Background：Quantifying syphilis prevalence is important for planning interventions and advocating for resources on syphilis.However,data on large sample studies regarding the prevalence of syphilis among reproductive-age women in rural China were not available for analysis.The aim of the study was to determine the prevalence,epidemiological characteristics,and related factors of syphilis infection among reproductive-age women in rural China.Methods：Data were obtained from a nationwide,population-based,cross-sectional study under the National Free Preconception Health Examination Project which covered all the 31 provinces in China's Mainland.Women intending to get pregnant within the next 6 months were enrolled between January 1,2010,and December 31,2012.Sociodemographic,gynecological and obstetric characteristics,and other relevant information were obtained through face-to-face interviews.Treponema pallidum particle agglutination assay test was used to detect positive samples of syphilis.Univariate and multivariate logistic regressions were performed to assess the associations between syphilis seropositivity and related factors.Results：The overall seroprevalence of syphilis （SPS） among the 2,044,126 women who received syphilis screening test during 2010-2012 was 0.37% （95% confidence interval [CI]：0.36-0.37%）.The SPS appeared 0.24% （95% CI：0.23-0.26%） and 0.66% （95% CI：0.59-0.72%） in women at 21-24 and 40-44 years of age,respectively,showing an increase of SPS,parallel with age,and the difference was significant.SPS was significantly higher in ethnic minorities than that in Han nationality （0.58% vs.0.35%,respectively,odds ratio [OR] =1.41,95% CI：1.30-1.53） and higher in workers than that in farmers （0.45% vs.0.36%,respectively,OR =1.27,95% CI：1.14-1.41）.Women with primary school or below level had a higher SPS as compared to those with college or above educational level （0.61% vs.0.32%,respectively,OR =2.49,95% CI：2.14-2.89）,and the increase reversely correlated with
基金the National Natural Science Foundation of China(Grant Nos.51872167 and 51672163)the Major Science and Technology Innovation Project of Shandong Province,China(Grant No.2019JZZY010210).
文摘Temperature-dependent and driving current-dependent electroluminescence spectra of two different InGaN/GaN multiple quantum well structures SA and SB are investigated,with the In composition in each well layer(WL)along the growth direction progressively increasing for SA and progressively decreasing for SB.The results show that SB exhibits an improved efficiency droop compared with SA.This phenomenon can be explained as follows:owing to the difference in growth pattern of the WL between these two samples,the terminal region of the WL in SB contains fewer In atoms than in SA,and therefore the former undergoes less In volatilization than the latter during the waiting period required for warming-up due to the difference in the growth temperature between well and barrier layers.This results in SB having a deeper triangular-shaped potential well in its WL than SA,which strongly confines the carriers to the initial region of the WL to prevent them from leaking to the p-GaN side,thus improving the efficiency droop.Moreover,the improvement in the efficiency droop for SB is also partly attributed to its stronger Coulomb screening effect and carrier localization effect.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51672163 and 51872167)the Major Research Plan of the National Natural Science Foundation of China(Grant No.91433112)。
文摘Photoluminescence(PL) spectra of two different green InGaN/GaN multiple quantum well(MQW) samples S1 and S2,respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K-3 30 K and an excitation power range of 0.001 mW-75 mW.The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range,the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples,and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1;in the highest excitation power range,the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1,and by the Coulomb screening effect for S2.The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature,and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatchinduced quantum-confined Stark effect.This explanation is also supported by other relevant measurements of the samples,such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51672163,51872167,and 61504044)the Major Research Plan of the National Natural Science Foundation of China(Grant No.91433112)
文摘The photoluminescence(PL) properties of blue multiple InGaN/GaN quantum well(BMQW) and green multiple InGaN/GaN quantum well(GMQW) formed on a single sapphire substrate are investigated. The results indicate that the peak energy of GMQW-related emission(PG) exhibits more significant "S-shaped" dependence on temperature than that of BMQW-related emission(PB), and the excitation power-dependent carrier-scattering effect is observed only in the PG emission;the excitation power-dependent total blue-shift(narrowing) of peak position(line-width) for the PGemission is more significant than that for the PBemission;the GMQW shows a lower internal quantum efficiency than the BMQW. All of these results can be attributed to the fact that the GMQW has higher indium content than the BMQW due to its lower growth temperature and late growth, and the higher indium content in the GMQW induces a more significant compositional fluctuation, a stronger quantum confined Stark effect, and more non-radiative centers.
