Impacts of carrier trapping and ion migration on charge transport of perovskite solar cells with TiOx electron transport layer

The ion migration in perovskite materials has been extensively studied by researchers, but the charge dynamic distribution caused by ion migration and carrier trapping is partly unclear. To investigate the impacts of ion migration and defect induced carrier trapping on the carrier transport and the carrier collection, we measured the evolution of the photocurrent response in microseconds, milliseconds and seconds for the perovskite solar cells pretreated at different biases. Our results reveal that the photocurrent of the solar cells pretreated at negative bias decreases with time and achieves its minimum at several milliseconds, then rises and achieves its maximum at tens of seconds. For the device pretreated at positive bias beyond built-in potential, the time to reach maximum photocurrent is much shorter than that of the solar cell pretreated at negative bias. The transient photocurrent responses to the sequence of single-light-pulses also show that there is obvious carrier trapping in a positive bias treated device, which indicates that defect induced carrier trapping is the critical factor for the perovskite solar cells with an n-TiO_x electron transport layer. In order to improve the performance of the perovskite solar cells with nano-TiO_x ETL, it is very necessary to significantly reduce defects. Our results also demonstrate that cation accumulation at the interface between the perovskite active layer and ETL can enhance the device performance to a certain extent.

The ion migration in perovskite materials has been extensively studied by researchers, but the charge dynamic distribution caused by ion migration and carrier trapping is partly unclear.     

Neuroprotective constituents from the aerial parts of Cannabis sativa L. subsp. sativa

Five new compounds including three new cannabinoids, cannabisativas A–C (1–3), two new phenolic acids, (7Z,9Z)-cannabiphenolic acid A (4) and (8S,9Z)-cannabiphenolic acid B (5), together with twelve known compounds (6–17), were isolated from the aerial parts of Cannabis sativa L. subsp. sativa. The structures of 1–5 were established on the basis of extensive 1D, 2D NMR and HRESIMS analysis. The absolute configurations were determined by comparison between their experimental and calculated spectra of electronic circular dichroism (ECD) or the modified Mosher''s method. The neuroprotective effects of the compounds 1–17 were evaluated on PC 12 cells. Compounds 12, 13 and 15 showed potential protective effects against H₂O₂-induced damage.

5 new compounds including 3 new cannabinoids, cannabisativas A–C, 2 new phenolic acids, (7Z,9Z)-cannabiphenolic acid A and (8S,9Z)-cannabiphenolic acid B, together with 12 known compounds, were isolated from the aerial parts of Cannabis sativa L. subsp. sativa.     

Thermogravimetric analysis of soot combustion in the presence of ash and soluble organic fraction

Soot (Printex U, PU) combustion in the presence of ash and soluble organic fraction (SOF) was studied by thermogravimetric analysis (TGA). The comprehensive combustion index, combustion stability index and peak temperature were collected to evaluate the combustion performance of soot/ash/SOF mixtures. Compared with SiO₂, Fe₂O₃ and CaSO₄ nanoparticles, ZnO nanoparticles efficiently accelerate soot combustion with excellent oxygen carrying abilities. When the weight ratio of the PU/ZnO mixture is 1 : 1, this acceleration effect is maximized in the soot combustion process. The comprehensive combustion and combustion stability indices increase from 0.667 × 10⁻⁷%² min⁻² °C⁻³ and 23.53 × 10⁵ to 1.296 × 10⁻⁷%² min⁻² °C⁻³ and 39.53 × 10⁵, compared to pure PU, respectively. Compared with the PU/ZnO mixture, the soot combustion had inferior results after adding two oils as the simulative SOF. The 15W lubricant had the minimum negative impact compared to 0# diesel fuel. The comprehensive combustion and combustion stability indices reach the maximum values of 1.074 × 10⁻⁷%² min⁻² °C⁻³ and 33.29 × 10⁵ at the 1 : 1 : 0.1 weight ratio of PU/ZnO/15W, which grew by 62% and 42% compared to pure PU, respectively. This work contributes to an understanding of the combined effect of ash and SOF on soot combustion.

Soot (Printex U, PU) combustion in the presence of ash and soluble organic fraction (SOF) was studied by thermogravimetric analysis (TGA).     

Synthesis,characterization, and catalytic application of hierarchical nano-ZSM-5 zeolite

Hierarchical nano-ZSM-5 zeolites (Z5-X) with different grain sizes were synthesized by varying amounts of 3-glycidoxypropyltrimethoxysilane (KH-560) in the hydrothermal synthesis strategy. Moreover, the conventional ZSM-5zeolite(Z5), which was prepared without KH-560, was used as the reference sample. The crystalline phases, morphologies, porous characteristics, Si/Al molar ratios and acidic properties of all fresh catalysts were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), N₂ adsorption–desorption, inductively coupled plasma atomic emission spectroscopy (ICP) and temperature programmed desorption of ammonia (NH₃-TPD) techniques. Results show that the grain size and strong acid amount of zeolite decreased with the increasing amount of KH-560. The micropore surface areas and the corresponding volume of Z5-X changed less compared with Z5. Consequently, the high shape-selectivity of zeolite was preserved well under the addition of KH-560. However, the mesopore surface areas and the corresponding volume increased significantly with the increasing amount of KH-560. Benefiting from the abundant hierarchical structure, the Z5-X catalysts exhibited a larger coke capacity than the Z5 catalyst. The coke depositions of all the deactivated catalysts were characterized by the thermogravimetric technique (TG), and the results are indicative of the decreased average rate of coke deposition with an increasing amount of KH-560, which could result from the gradually reduced strong acid amount and the nano-sized crystallites. The catalytic performance of methanol-to-aromatics (MTA) indicates that the Z5-0.12 catalyst exhibited higher catalytic activity and selectivity of BTX as the reaction was prolonged, which could result from the synergistic effect among the proper strong acid amount, the smaller zeolite grain size, and the abundant hierarchical structure.

The crystal size and strong acid amounts of ZSM-5 decrease and the mesopores increase with increasing of KH-560. High MTA catalytic performance could be obtained under synergistic effect of proper strong acid amount, smaller crystal size and abundant hierarchical structure.     

Enhanced light emission of quantum dot films by scattering of poly(zinc methacrylate) coating CdZnSeS/ZnS quantum dots and high refractive index BaTiO3 nanoparticles

Quantum dots (QDs) have received considerable attention in information displays owing to their high quantum yield, high colour purity and low-cost fabrication. However, light emission for ultra-thin QD films with low mass percentage of QDs still need to be improved because the blue light can directly transmit the films, leading to insufficient energy to excite the QDs. In this study, we report QD films based on a poly(zinc methacrylate) coating with alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs@PZnMA) together with high refractive-index BaTiO₃ nanoparticles to enhance the scattering coefficient of the QD films. Results demonstrate a 7.5-fold increase in the absorption coefficient, 11.3-fold increase in the scattering coefficient, 8.5-fold increase in the optical density (OD) and 8.6-fold increase in the green-light emission of QD films, compared with films that have the same mass percentage of pristine QDs. This approach provides a promising strategy for developing QD optical films with high scattering and enhanced light emission for flexible displays.

We report QD films based on a poly(zinc methacrylate) coating with alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs@PZnMA) together with high refractive-index BaTiO₃ nanoparticles to enhance the scattering coefficient of the QD films.     

基于时空分析的急诊护理人力资源管理

目的 探讨急诊患者的时空分布规律,优化急诊护理人力资源的管理。方法 回顾分析2017-2019年笔者所在医院急诊科就诊患者的资料,对患者每年不同月份、不同工作日、不同时间段及省内外就诊辐射特点进行时空分布的统计分析。结果 急诊患者就诊量呈逐年上升趋势,节假日的日均就诊量最高,就诊患者大部分集中在1-4月和9-12月,9∶00和20∶00是全天就诊的2个高峰时间点。空间上以笔者所在医院为中心就诊患者呈中心辐射状分布,人群主要为湖北省内患者为主,省内集中在武汉、黄冈、孝感等城市;省外以河南居首,其次为江西、湖南、浙江。结论 应根据患者的时空分布规律,科学合理地配置及利用护理人力资源,以保障患者安全和提高急救护理质量。     

山西省汾阳市中学生饮食行为及其与高血压患病的关系

目的:了解山西省汾阳市中学生饮食行为及其与高血压患病的关系,为山西省汾阳市中学生高血压的防治提供一定的参考依据。方法:于2018年9月—2019年1月采用随机抽样的方法,在山西省汾阳市抽取8642名中学生进行问卷调查。结果:山西省汾阳市8642名中学生中高血压342人,患病率为3.96%。多因素非条件Logistic回归分析显示,吃饭速度较快、饮食口味偏咸或者偏甜、超重或肥胖、有高血压家族史是汾阳市中学生高血压患病的危险因素,而每周饮牛奶的频率≥6次是汾阳市中学生高血压患病的保护因素。结论:吃饭速度、饮食口味、每周饮牛奶的次数等可以影响到山西省汾阳市中学生高血压的患病情况,家长应该引起足够的重视,对中学生的饮食行为加以重视,对中学生高血压的预防起到一定的作用。     

共享决策研究的文献计量学分析

目的:通过对2010年—2019年共享决策研究进行分析,探讨该领域研究热点及发展趋势,为今后我国共享决策领域的研究提供参考.方法:检索选取Web of Science核心合集收录的2010年—2019年共享决策研究的文献,并使用CiteSpace进行统计分析.结果:共享决策研究的发文量逐年增加,其研究力量主要集中在美国、英国和加拿大等发达国家;高产作者为LEGARE F,得到5个名词术语聚类为前列腺癌(prostate cancer)、癌症(cancer)、服药依从性(medical adherence)、决策辅助(decision aid)和决策研究(decision study).结论:共享决策研究大多集中在美国,研究热点以癌症为主,关注癌症防护、安宁疗护、精神疾患以及决策辅助工具应用以及理论研究等方面.