Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is...Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is vital to improve the kinetics of ammonia synthesis and obtain a less energy-intensive process.Herein,carbon-encapsulated mixed-valence Fe_(7)(PO_(4))_(6) was prepared and applied as an electrocatalyst for high-efficiency NRR.A dramatic faradaic efficiency(FE)of 36.93%and an NH_(3) production rate of 13.1μg h^(-1) mg_(cat)^(-1) were obtained at-0.3 V versus RHE,superior to nearly all Fe-based catalysts.Experiments and DFT calculations revealed that the superior performance was ascribed to the synergistic effect of mixed-valence iron pair,which braked the linear correlations to improve the kinetics of ammonia from collaborative hydrogenation and*NH_(3) separation.This work proves the feasibility of mixedvalence catalysts for nitrogen reduction and thus opening a new avenue towards artificial nitrogenfixation catalysts.展开更多
AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional ...AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional study.Totally 130 ON subjects(200 eyes) without ON onset within 6mo were included, who underwent BCVA assessment,peripapillary retinal nerve fibre layer(pRNFL) and macular segmented layers evaluation by optical coherence tomography(OCT).RESULTS: For the 0-18y cohort, the final BCVA(logMAR)was significantly better and less frequent recurrences than adult cohorts(P=0.000). The final BCVA(logMAR) in all age-cohorts of the ON patients had negative and linear correlations to the pRNFL thicknesses and macular retinal ganglion cell layer(mRGCL) volumes, when the pRNFL thicknesses were reduced to the thresholds of 57.2-67.5 μm or 0.691-0.737 mm;in mRGCL volumes, respectively, with the strongest interdependence in the 19-40y cohort. The ON patients from varying age cohorts would be threatened by blindness when their pRNFL thicknesses dropped 36.7-48.3 μm or the mRGCL volumes dropped to 0.495-0.613 mm;.CONCLUSION: The paediatric ON has best prognosis and young adult ON exhibits perfectly linear correlations of final vision and structural loss. The pRNFL and the mRGCL could be potential structural markers to predict the vision prognosis for varying-age ON patients.展开更多
Five optimized geometries of F-?(H2O)n (n = 1, 2) were obtained with ab initio calculation at the B3LYP/6-311++G** level. The accurate intermonomer interaction energy was calculated using the MP2 electron correlation ...Five optimized geometries of F-?(H2O)n (n = 1, 2) were obtained with ab initio calculation at the B3LYP/6-311++G** level. The accurate intermonomer interaction energy was calculated using the MP2 electron correlation correction as well as the basis set superposition error correction by the Boys-Bernardi “counterpoise” protocol. Natural bond orbital (NBO) theory was applied to quantify the relative strength of these interactions and account for their effects on the stability, structural and vibrational parameters of Fˉ?(H2O)n (n = 1, 2). It is shown that the charge transferring from the lone pair of F-1 to the σ?OH(…F) antibonding orbital is important. The results indicate the occupancy of σ?OH(…F) is increased (denoted ?σ?OH(…F)) and the σOH(…F) bond is leng- thened (denoted ?ROH(…F)), leading to the red-shift and the red-shift values have linear correlation with both ?σ?OH(…F) and ?ROH(…F).展开更多
<b>Background:</b> Erectile dysfunction (ED) is a common condition in general population. It has a negative impact on the couple’s quality of life. In 1995, it was estimated that it affected 152 million p...<b>Background:</b> Erectile dysfunction (ED) is a common condition in general population. It has a negative impact on the couple’s quality of life. In 1995, it was estimated that it affected 152 million people worldwide, and that it would affect more than 322 million people in 2025 with a large increase in developing countries. Several studies have suggested a causal link between ED and cardiovascular disease. In the Democratic Republic of Congo, no studies exist on this subject. Nonetheless, we are seeing increased promotion on the management of sexual disorders in our media, which could testify to the extent of this problem. <b>Objective:</b> To assess the extent of cardiovascular risk factors for ED in Kinshasa. <b>Material and Methods:</b> This is a cross-sectional study for analytical purposes. It collected several categories of individuals from May 1 to October 31, 2018. The severity of ED was assessed by the IIEF-5 score and the associated risk factors sought via logistic regression. <b>Results:</b> The mean age of the respondents was 59.9 ± 19.2 years, more than half of the respondents were over the age of 60 years old (60%). The ED proportion was 78.8%, and 75% of respondents had at least moderate ED. This anomaly was significantly elevated among respondents aged over 60 years (94.8%), diabetics (87.5%), hypertensive patients (92.3%) and stroke victims (86%). The independently associated risk factors were: age > 60 years [ORa: 9.87;95% CI: 6.42 - 10.48, <i>p</i> < 0.001], diabetes mellitus [ORa: 2.99;95% CI: 1.80 - 4.95, <i>p</i> = 0.013] and the stroke [ORa: 2.1;95% CI: 1.36 - 3.39;<i>p</i> = 0.012%]. The age threshold predicting ED was 67 years. <b>Conclusion:</b> ED is a frequent disorder in our environment and likely to affect the quality of life of men who suffer from it. There is an ED and cardiovascular risk factors correlation. A proactive attitude of the caregiver in current practice would allow early detection of ED with a view to early and optimal management.展开更多
Accurately identifying distribution network topol-ogy,which tends to be a mesh configuration with increasing penetration rate of distributed energy resources(DERs),is critical for reliable operation of a smart distrib...Accurately identifying distribution network topol-ogy,which tends to be a mesh configuration with increasing penetration rate of distributed energy resources(DERs),is critical for reliable operation of a smart distribution network.Multicollinearity among node voltages makes existing topology identification methods unstable and inaccurate.Considering partial correlation analysis can reveal the intrinsic correlation of two variables by eliminating the influence of other variables,this paper develops a novel data-driven method based on partial correlation analysis to identify distribution network topology(radial,mesh,or including DERs)using only historical voltage amplitude data.First,maximum spanning tree of network is generated through Prim algorithm.Then,the loops of network are identified by taking tree neighbors as controlling variables in partial correlation analysis.Finally,a new topology verification mechanism based on partial correlation analysis is developed to correct wrong connections caused by multicollinearity.Test results on IEEE 33-node system,IEEE 123-node system and practical distribution network demonstrate that our method outperforms common data-driven methods,and can robustly identify both radial and mesh distribution network with DERs.IndexTerms-Data-driven,linear correlation,partial correlation,smart meter,topology identification.展开更多
尽管许多催化剂已经被报道用于电化学转换二氧化碳(CO_(2))到甲烷(CH_(4))或者二碳(C_(2))产物,然而目前对各种产物之间的关联的研究仍然不够深入,这阻碍着催化剂设计的进一步发展.本文通过研究商品化铜粉(Cu)作为CO_(2)电还原的阴极催...尽管许多催化剂已经被报道用于电化学转换二氧化碳(CO_(2))到甲烷(CH_(4))或者二碳(C_(2))产物,然而目前对各种产物之间的关联的研究仍然不够深入,这阻碍着催化剂设计的进一步发展.本文通过研究商品化铜粉(Cu)作为CO_(2)电还原的阴极催化剂,发现一氧化碳中间体(*CO)在催化剂表面的覆盖度在较大的电位区间内会保持基本不变,且在这个电位区间内,CH_(4)与C_(2)产物的分电流密度呈线性关系,这一结论得到了理论动力学分析的支持.由于*CHO中间体分子是产生CH_(4)(*CHO→CH_(4))与C_(2)产物(*CHO+*CO→C_(2))的共同中间体,我们进一步猜想该线性关系是普遍存在的,且可以通过调节催化剂表面的吸附氢(*H)或者一氧化碳(*CO)的覆盖度,以分别促进CH_(4)或者C_(2)产物的生成,并改变线性关系的斜率.为了验证该猜想,本文合成了碳包覆的铜(Cu@C)催化剂,其中碳层可增加催化剂表面的*H覆盖度从而提高CH_(4)的产生,最高的CH_(4)法拉第效率(FE_(CH_(4)))达到52%,相应的分电流密度为±337 m A cm±2.另一方面,合成了银掺杂的铜催化剂,其中掺杂的银用以产生CO,以进一步提高催化剂表面的*CO覆盖度.该催化剂二氧化碳电还原的选择性变成了C_(2)产物为主,最高C_(2)产物的法拉第效率(FE_(CH_(4)))达到79%,相应的分电流密度为±421 m A cm±2.不仅如此,在这两种催化剂上,CH_(4)与C_(2)产物的分电流密度仍然保持良好的线性关系.本文工作揭示了CH_(4)与C_(2)产物产率的线性关系,以及反应中间分子的调控策略,为电催化二氧化碳还原为不同的产物提供了参考.展开更多
基金supported by the National Natural Science Foundation of China(21908120 and 22109078)the Youth Innovation Team Project of Shandong Provincial Education Department(2019KJC023)。
文摘Electrochemical nitrogen reduction(NRR)is deemed as a consummate answer for the traditional Haber–Bosch technology.Breaking the linear correlations between adsorption and transition-state energies of intermediates is vital to improve the kinetics of ammonia synthesis and obtain a less energy-intensive process.Herein,carbon-encapsulated mixed-valence Fe_(7)(PO_(4))_(6) was prepared and applied as an electrocatalyst for high-efficiency NRR.A dramatic faradaic efficiency(FE)of 36.93%and an NH_(3) production rate of 13.1μg h^(-1) mg_(cat)^(-1) were obtained at-0.3 V versus RHE,superior to nearly all Fe-based catalysts.Experiments and DFT calculations revealed that the superior performance was ascribed to the synergistic effect of mixed-valence iron pair,which braked the linear correlations to improve the kinetics of ammonia from collaborative hydrogenation and*NH_(3) separation.This work proves the feasibility of mixedvalence catalysts for nitrogen reduction and thus opening a new avenue towards artificial nitrogenfixation catalysts.
基金Supported by the National High Technology Research and Development Program of China(863 Programme,No.2015AA020511)Clinical Support Foundation of PLA General Hospital,China(No.2016FC-TSYS-I016)。
文摘AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional study.Totally 130 ON subjects(200 eyes) without ON onset within 6mo were included, who underwent BCVA assessment,peripapillary retinal nerve fibre layer(pRNFL) and macular segmented layers evaluation by optical coherence tomography(OCT).RESULTS: For the 0-18y cohort, the final BCVA(logMAR)was significantly better and less frequent recurrences than adult cohorts(P=0.000). The final BCVA(logMAR) in all age-cohorts of the ON patients had negative and linear correlations to the pRNFL thicknesses and macular retinal ganglion cell layer(mRGCL) volumes, when the pRNFL thicknesses were reduced to the thresholds of 57.2-67.5 μm or 0.691-0.737 mm;in mRGCL volumes, respectively, with the strongest interdependence in the 19-40y cohort. The ON patients from varying age cohorts would be threatened by blindness when their pRNFL thicknesses dropped 36.7-48.3 μm or the mRGCL volumes dropped to 0.495-0.613 mm;.CONCLUSION: The paediatric ON has best prognosis and young adult ON exhibits perfectly linear correlations of final vision and structural loss. The pRNFL and the mRGCL could be potential structural markers to predict the vision prognosis for varying-age ON patients.
基金This work was supported by the Foundation of Education Committee of Gansu Province (021-227).
文摘Five optimized geometries of F-?(H2O)n (n = 1, 2) were obtained with ab initio calculation at the B3LYP/6-311++G** level. The accurate intermonomer interaction energy was calculated using the MP2 electron correlation correction as well as the basis set superposition error correction by the Boys-Bernardi “counterpoise” protocol. Natural bond orbital (NBO) theory was applied to quantify the relative strength of these interactions and account for their effects on the stability, structural and vibrational parameters of Fˉ?(H2O)n (n = 1, 2). It is shown that the charge transferring from the lone pair of F-1 to the σ?OH(…F) antibonding orbital is important. The results indicate the occupancy of σ?OH(…F) is increased (denoted ?σ?OH(…F)) and the σOH(…F) bond is leng- thened (denoted ?ROH(…F)), leading to the red-shift and the red-shift values have linear correlation with both ?σ?OH(…F) and ?ROH(…F).
文摘<b>Background:</b> Erectile dysfunction (ED) is a common condition in general population. It has a negative impact on the couple’s quality of life. In 1995, it was estimated that it affected 152 million people worldwide, and that it would affect more than 322 million people in 2025 with a large increase in developing countries. Several studies have suggested a causal link between ED and cardiovascular disease. In the Democratic Republic of Congo, no studies exist on this subject. Nonetheless, we are seeing increased promotion on the management of sexual disorders in our media, which could testify to the extent of this problem. <b>Objective:</b> To assess the extent of cardiovascular risk factors for ED in Kinshasa. <b>Material and Methods:</b> This is a cross-sectional study for analytical purposes. It collected several categories of individuals from May 1 to October 31, 2018. The severity of ED was assessed by the IIEF-5 score and the associated risk factors sought via logistic regression. <b>Results:</b> The mean age of the respondents was 59.9 ± 19.2 years, more than half of the respondents were over the age of 60 years old (60%). The ED proportion was 78.8%, and 75% of respondents had at least moderate ED. This anomaly was significantly elevated among respondents aged over 60 years (94.8%), diabetics (87.5%), hypertensive patients (92.3%) and stroke victims (86%). The independently associated risk factors were: age > 60 years [ORa: 9.87;95% CI: 6.42 - 10.48, <i>p</i> < 0.001], diabetes mellitus [ORa: 2.99;95% CI: 1.80 - 4.95, <i>p</i> = 0.013] and the stroke [ORa: 2.1;95% CI: 1.36 - 3.39;<i>p</i> = 0.012%]. The age threshold predicting ED was 67 years. <b>Conclusion:</b> ED is a frequent disorder in our environment and likely to affect the quality of life of men who suffer from it. There is an ED and cardiovascular risk factors correlation. A proactive attitude of the caregiver in current practice would allow early detection of ED with a view to early and optimal management.
基金supported by the National Key R&D Program of China(2020YFB0905900)science and technology project of SGCC(State Grid Corporation of China)(SGTJDKOODWJS 2100223)。
文摘Accurately identifying distribution network topol-ogy,which tends to be a mesh configuration with increasing penetration rate of distributed energy resources(DERs),is critical for reliable operation of a smart distribution network.Multicollinearity among node voltages makes existing topology identification methods unstable and inaccurate.Considering partial correlation analysis can reveal the intrinsic correlation of two variables by eliminating the influence of other variables,this paper develops a novel data-driven method based on partial correlation analysis to identify distribution network topology(radial,mesh,or including DERs)using only historical voltage amplitude data.First,maximum spanning tree of network is generated through Prim algorithm.Then,the loops of network are identified by taking tree neighbors as controlling variables in partial correlation analysis.Finally,a new topology verification mechanism based on partial correlation analysis is developed to correct wrong connections caused by multicollinearity.Test results on IEEE 33-node system,IEEE 123-node system and practical distribution network demonstrate that our method outperforms common data-driven methods,and can robustly identify both radial and mesh distribution network with DERs.IndexTerms-Data-driven,linear correlation,partial correlation,smart meter,topology identification.
基金supported by the National Key Research and Development Program of China(2018YFA0209401 and 2017YFA0206901)the National Natural Science Foundation of China(22025502 and 21975051)+1 种基金the Science and Technology Commission of Shanghai Municipality(21DZ1206800,19XD1420400)the Shanghai Municipal Education Commission(2019-01-07-00-07-E00045)。
文摘尽管许多催化剂已经被报道用于电化学转换二氧化碳(CO_(2))到甲烷(CH_(4))或者二碳(C_(2))产物,然而目前对各种产物之间的关联的研究仍然不够深入,这阻碍着催化剂设计的进一步发展.本文通过研究商品化铜粉(Cu)作为CO_(2)电还原的阴极催化剂,发现一氧化碳中间体(*CO)在催化剂表面的覆盖度在较大的电位区间内会保持基本不变,且在这个电位区间内,CH_(4)与C_(2)产物的分电流密度呈线性关系,这一结论得到了理论动力学分析的支持.由于*CHO中间体分子是产生CH_(4)(*CHO→CH_(4))与C_(2)产物(*CHO+*CO→C_(2))的共同中间体,我们进一步猜想该线性关系是普遍存在的,且可以通过调节催化剂表面的吸附氢(*H)或者一氧化碳(*CO)的覆盖度,以分别促进CH_(4)或者C_(2)产物的生成,并改变线性关系的斜率.为了验证该猜想,本文合成了碳包覆的铜(Cu@C)催化剂,其中碳层可增加催化剂表面的*H覆盖度从而提高CH_(4)的产生,最高的CH_(4)法拉第效率(FE_(CH_(4)))达到52%,相应的分电流密度为±337 m A cm±2.另一方面,合成了银掺杂的铜催化剂,其中掺杂的银用以产生CO,以进一步提高催化剂表面的*CO覆盖度.该催化剂二氧化碳电还原的选择性变成了C_(2)产物为主,最高C_(2)产物的法拉第效率(FE_(CH_(4)))达到79%,相应的分电流密度为±421 m A cm±2.不仅如此,在这两种催化剂上,CH_(4)与C_(2)产物的分电流密度仍然保持良好的线性关系.本文工作揭示了CH_(4)与C_(2)产物产率的线性关系,以及反应中间分子的调控策略,为电催化二氧化碳还原为不同的产物提供了参考.
