Chemical bonding of perovskite LaFeO_(3) with Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2) to moderate anion redox for achieving high cycling stability

Oxygen anion redox reaction provides a high theoretical capacity for Li-rich manganese-based cathodes.However,irreversible surface oxygen release often results in further oxygen loss and exacerbates the decomposition of the electrolyte,which could reduce the capacity contribution from the anionic redox and produce more acidic substances to corrode the surface of the material.In this paper,the surface oxygen release is suppressed by moderating oxygen anion redox activity via constructing chemical bonds between M(M=Fe and La)in LaFeO_(3)and surface oxygen anions of Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2).The constructed interface layer stabilizes the surface lattice oxygen and retards the electrolyte from being attacked by the nucleophilic oxygen generated in the process of oxygen release,as evidenced by Differential Electrochemical Mass Spectrometry(DEMS)and X-ray Photoelectron Spectroscopy(XPS)detections.Moreover,in the charge and discharge process,the formed FeF_(3),located at the cathode electrolyte interfacial layer,is conducive to the stability of the cathode surface.The modified Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)electrode with 3 wt%LaFeO_(13)exhibits a high specific capacity of 189.5 mA h g-at 1C(200 mA g^(-1))after 150 cycles with capacity retentions of 96.6%,and 112.6 mA h g^(-1)(84.7%)at 5C after 200 cycles higher than the pristine sample.This study provides a rational design chemical bonding method to suppress the oxygen release from the cathode surface and enhance cyclic stability.

Multi-scale Cyclone Activity in the Changjiang River–Huaihe River Valleys during Spring and Its Relationship with Rainfall Anomalies

Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River-Huaihe River valleys （CHV） were developed. We studied the characteristics of the multi-scale cyclone activity that affects CHV and its relationship with rainfall during spring since 1979. The results indicated that the automated identification algorithm for cyclones proposed in this paper could intuitively identify multi-scale cyclones that affect CHV. The algorithm allows for effectively describing the shape and coverage area of the closed contours around the periphery of cyclones. We found that, compared to the meso- and sub-synoptic scale cyclone activities, the synoptic-scale cyclone activity showed more intimate correlation with the overall activity intensity of multi-scale CHV cyclones during spring. However, the frequency of occurrence of sub-synoptic scale cyclones was the highest, and their effect on changes in CHV cyclone activity could not be ignored. Based on the area of impact and the depth of the cyclones, the sub-synoptic scale, synoptic scale and comprehensive cyclone intensity indices were further defined, which showed a positive correlation with rainfall in CHV during spring. Additionally, the comprehensive cyclone intensity index was a good indicator of strong rainfall events.

Multi-dimensional blind separation method for STBC systems

Intercepted signal blind separation is a research topic with high importance for both military and civilian communication systems. A blind separation method for space-time block code （STBC） systems is proposed by using the ordinary independent component analysis （ICA）. This method cannot work when specific complex modulations are employed since the assumption of mutual independence cannot be satisfied. The analysis shows that source signals, which are group-wise independent and use multi-dimensional ICA （MICA） instead of ordinary ICA, can be applied in this case. Utilizing the block-diagonal structure of the cumulant matrices, the JADE algorithm is generalized to the multidimensional case to separate the received data into mutually independent groups. Compared with ordinary ICA algorithms, the proposed method does not introduce additional ambiguities. Simulations show that the proposed method overcomes the drawback and achieves a better performance without utilizing coding information than channel estimation based algorithms.

A multifunctional rock testing system for rock failure analysis under different stress states: Development and application

The stress state in a rock mass is complex. Stress redistribution around underground excavation may lead to various failure modes, including compressive-shear, tensile-shear, and tensile failures. The ability to perform laboratory tests with these complex stress states is significant for establishing new strength criteria. The present paper introduces a new rock testing system with “tensile-compressive-shear”loading functions. The device includes bi-directional and double-range hydraulic cylinders, auxiliary loading equipment, and roller rows that can perform direct compressive-shear tests, direct tensile tests,and direct tensile-shear tests. The testing system provides maximum vertical and lateral loading forces of2000 k N and allows testing cubical rock specimens with dimensions of 0.5 m × 0.5 m × 0.5 m. The performance of the testing machine was evaluated by testing a rock-like material based on cement mortar under compressive-shear, tensile, and tensile-shear stress states. The failure process and deformation characteristics were monitored during loading using acoustic emission(AE) transient recorder,piezoelectric AE sensors, a high-speed camera, and a thermal infrared camera. The failure mechanism was investigated by analyzing AE counts, AE amplitude, strain, and temperature changes on the rock specimen surface. The test results confirmed that the testing system could successfully simulate the abovementioned stress path. The AE counts and amplitude responses were influenced by different failure modes. The temperature response during the compressive-shear test indicated the development of a high-temperature band on the rock specimen surface. In contrast, a negligible temperature change was observed during the tensile and tensile-shear tests. The newly developed multifunctional rock testing system allows laboratory tests under various failure modes. The monitoring results of multiple variables during rock failure tests provide valuable information on failure characteristics.

Using self-location to calibrate the errors of observer positions for source localization

The uncertainty of observers＇ positions can lead to significantly degrading in source localization accuracy. This pa-per proposes a method of using self-location for calibrating the positions of observer stations in source localization to reduce the errors of the observer positions and improve the accuracy of the source localization. The relative distance measurements of the two coordinative observers are used for the linear minimum mean square error （LMMSE） estimator. The results of computer si-mulations prove the feasibility and effectiveness of the proposed method. With the general estimation errors of observers＇ positions, the MSE of the source localization with self-location calibration, which is significantly lower than that without self-location calibra-tion, is approximating to the Cramer-Rao lower bound （CRLB）.

Research on the Reform and Practice of “Basic Nursing Skills Practice” Course Assessment

Objective: “Basic Nursing Skills Practice” is a key course connecting classroom and clinical teaching in nursing specialty teaching. Nursing practice ability is one of the core abilities of nurse practitioners. Therefore, the teaching quality of this course is directly related to the quality of nursing work. To improve the teaching quality of practical course, the assessment reform of the “Basic Nursing Skills Practice” course was carried out among the nursing undergraduates to explore a reasonable and fair assessment mechanism. Method: In the assessment of “Basic Nursing Skills Practice” course, the assessment included individual skill operation assessment, virtual simulation assessment and team comprehensive skill assessment. The assessment proportion was adjusted from 100% for the final examination to 50% for the middle and final examinations respectively. The assessment method was changed from individual skills assessment at the end of the term to a combination of individual skills assessment at the midterm and virtual simulation assessment and team skills assessment at the end of the term. The method has changed from summative evaluation to a combination of formative evaluation and summative evaluation, and self-made questionnaire was used to investigate the effect. Results: After implementing the assessment reform, 86.84% of the students were satisfied with the assessment reform, and the percentage of students with scores above 80 reached 100%. The highest score is 93.0, while the lowest score is 83.0, and the average score was 88.0. Conclusions: High satisfaction of students with basic nursing skills examination reform promoted the learning effectiveness and professional emotions, cultivated comprehensive quality and ability, promoted the realization of talent training objectives.

卤化物固态电解质研究进展

全固态电池因其高能量密度和高安全性而成为具有发展前景的下一代储能技术。开发具有高室温离子电导率、优异化学/电化学稳定性、良好正/负极兼容性的固态电解质是实现全固态电池实用化的关键。卤化物固态电解质因其优异的电化学窗口、高正极稳定性、可接受的室温锂离子电导率等优势,受到了广泛的关注。本文通过对近年来卤化物电解质的相关研究进行总结,综述了该类电解质的组成、结构、离子传导路径及制备方法,并分析了金属卤化物电解质的电导率、稳定性特点,归纳了近年来该电解质在全固态电池中具有代表性的应用,并基于以上总结和分析,指出了卤化物固态电解质的研究难点及发展方向。

Automated Pavement Crack Detection Using Deep Feature Selection and Whale Optimization Algorithm

Pavement crack detection plays a crucial role in ensuring road safety and reducing maintenance expenses.Recent advancements in deep learning(DL)techniques have shown promising results in detecting pavement cracks;however,the selection of relevant features for classification remains challenging.In this study,we propose a new approach for pavement crack detection that integrates deep learning for feature extraction,the whale optimization algorithm(WOA)for feature selection,and random forest(RF)for classification.The performance of the models was evaluated using accuracy,recall,precision,F1 score,and area under the receiver operating characteristic curve(AUC).Our findings reveal that Model 2,which incorporates RF into the ResNet-18 architecture,outperforms baseline Model 1 across all evaluation metrics.Nevertheless,our proposed model,which combines ResNet-18 with both WOA and RF,achieves significantly higher accuracy,recall,precision,and F1 score compared to the other two models.These results underscore the effectiveness of integrating RF and WOA into ResNet-18 for pavement crack detection applications.We applied the proposed approach to a dataset of pavement images,achieving an accuracy of 97.16%and an AUC of 0.984.Our results demonstrate that the proposed approach surpasses existing methods for pavement crack detection,offering a promising solution for the automatic identification of pavement cracks.By leveraging this approach,potential safety hazards can be identified more effectively,enabling timely repairs and maintenance measures.Lastly,the findings of this study also emphasize the potential of integrating RF and WOA with deep learning for pavement crack detection,providing road authorities with the necessary tools to make informed decisions regarding road infrastructure maintenance.

聚乳酸基层状纳米复合材料的研究进展

聚乳酸由于其良好的生物降解性、力学性能以及可加工性,具有极大的应用潜力,但是却面临脆性大、耐热温度低、阻燃性能差等缺点。而层状纳米材料是一类具有层状纳米结构,颗粒尺度为纳米或亚微米的纳米材料,具有优异的力学性能、热稳定性能、气体阻隔性能、电性能及化学性能。因此,使用层状纳米材料对聚乳酸进行改性,可以制备出具有优异性能的聚乳酸基纳米复合材料。文中重点综述了聚乳酸基层状硅酸盐、聚乳酸基层状双氢氧化物、聚乳酸基石墨烯及其衍生物3类纳米复合材料最新研究进展。

Altitudinal patterns of stand structure and herb layer diversity of Picea schrenkiana forests in the central Tianshan Mountains,Northwest China

Altitude is a useful indicator to examine patterns of forest structure and species diversity in relation to environmental factors.In this study,the altitude patterns of forest stand structure and species diversity were analyzed across 20 plots in the Tianchi Nature Reserve,Northwest China.The results showed that mean stem height（Hm）,maximum stem height（Hmax） and mean stem diameter at breast height（Dm） of Picea schrenkiana trees all decreased significantly with increasing altitude.Potential tree height（H＊） decreased while stem taper increased significantly as altitude increased,suggesting remarkable altitudinal changes in biomass allocation between the diameter and height growth of Picea schrenkiana.Understory herbaceous richness increased significantly with increasing altitude,or with decreasing total basal area（TBA）,Hm and stand volume（Volume）.High light availability for understory herbs might account for the higher species richness at high altitude.Sorensen Index decreased significantly with the increase in altitude intervals,while the Cody Index demonstrated a converse pattern,suggesting greater differences in species composition with larger distances.

Influence of stress wave-induced disturbance on ultra-low friction in broken blocks

Deep rock mass tends to be broken into blocks when mining for materials deep below the surface.The rock layer of the roof of the mine can be regarded as a system of blocks of fractured rock mass.When subjected to high ground stress and mining-induced disturbance,the efect of the ultra-low friction of the block system easily becomes apparent,and can induce rock burst and other accidents.By taking the block of rock mass as research object,this study developed a test system for ultra-low friction to experimentally examine its efects on the broken blocks under stress wave-induced disturbance.We used the horizontal displacement of the working block as the characteristic parameter refecting the efect of ultra-low friction,and examine its characteristic laws of horizontal displacement,acceleration,and energy when subjected to the efects of ultra-low friction by changing the frequency and amplitude of the stress wave-induced disturbance.The results show that the frequency of stress wave-induced disturbance is related to the generation of ultra-low friction in the broken block.The frequency of disturbance of the stress wave is within 1–3 Hz,and signifcantly increases the maximum acceleration and horizontal displacement of the broken blocks.The greater the intensity of the stress wave-induced disturbance is,the higher is the degree of block fragmentation,and the more likely are efects of ultra-low friction to occur between the blocks.The greater the intensity of the horizontal impact load is,the higher is the degree of fragmentation of the rock mass,and the easier it is for the efects of ultra-low friction to occur.Stress wave-induced disturbance and horizontal impact are the main causes of sliding instability of the broken blocks.When the dominant frequency of the kinetic energy of the broken block is within 20 Hz,the efects of ultra-low friction are more likely.

Evolution characteristics of precursor information of coal and gas outburst in deep rock cross‑cut coal uncovering

As mines become deeper,the potential for coal and gas outbursts in deep rock cross-cut coal uncovering is enhanced.The outburst precursors are unclear,which restricts the effectiveness and reliability of warning systems.To reveal the evolution characteristics of coal and gas outburst precursor information in deep rock cross-cut coal uncovering,briquette specimens are constructed and experiments are conducted using a self-developed true triaxial outburst test system.Using acoustic emission monitoring technology,the dynamic failure of coal is monitored,and variations in the root mean square(RMS)of the acoustic emissions allow the effective cracking time and effective cracking gas pressure to be defined.These characteristics are obviously different in deep and shallow coal.The characteristic parameters of gas outburst exhibit stepwise variations at different depths.The RMS and cumulative RMS have stepped failure characteristics with respect to changes in gas pressure.The characteristic parameters of coal failure are negatively correlated with the average in-situ stress and effective stress,but positively correlated with the lateral pressure coefficient of in-situ stress and the critical gas pressure.The transition characteristics are highly sensitive in all cases.The critical depth between deep and shallow coal and gas outbursts is 1700 m.The expansion multiple of acoustic emission intensity from the microfracture stage to the sharp-fracture stage of coal is defined as the outburst risk index,N1.For depths of 1100–1700 m,N1≥7 denotes a higher risk of outburst,whereas at depths of 1700–2500 m,N1≥3 indicates enhanced risk.

LLR Processing of Polar Codes in Concatenation Systems

This paper studies the decoding performance of low-density parity-check(LDPC)codes in a serial concatenation system with polar codes employing the successive cancellation(SC)decoding.It is known that the absolute incorrect log-likelihood ratio(LLR)values from the SC decoding can be very large.This phenomenon dramatically deteriorates the error correcting performance of the outer LDPC codes.In this paper,the LLR values of polar codes are regulated by a log processing before being sent to the LDPC decoder.Simulation results show that the log processing is an efficient approach with a low optimization complexity compared with the existing procedures to improve the performance of the serial concatenation systems.

Optimal Reservoir Operation Using Stochastic Dynamic Programming

This paper focused on the applying stochastic dynamic programming (SDP) to reservoir operation. Based on the two stages decision procedure, we built an operation model for reservoir operation to derive operating rules. With a case study of the China’s Three Gorges Reservoir, long-term operating rules are obtained. Based on the derived operating rules, the reservoir is simulated with the inflow from 1882 to 2005, which the mean hydropower generation is 85.71 billion kWh. It is shown that the SDP works well in the reservoir operation.

Definition and analysis of the circulation indices of polar vortex at 10 hPa in the Northern Hemisphere

A set of circulation indices are defined and calculated to characterize monthly mean polar vortex at 10 hPa geopotential height chart in the Northern Hemisphere,including area–(S),intensity–(P) and center position (λc,φc)–indices by use of 1948–2007 NCEP/NCAR 10 hPa monthly height data.These indices series are used to investigate the seasonal variation and interannual anomaly of polar vortex,along with the relations with global warming,ozone anomaly and Arctic Oscillation (AO).The results show that (1) there is anticyclonic (cyclonic) from Jun.to Aug.(from Sep.to Mar.).The change of spring circulation pattern is slower than that of autumn.(2) S can be replaced by P due to the interannual synchronal variations of the intensity and area for polar vortex.The interannual (interdecadal) variations of P are significant in Jan.(Jul.).(3) The anomalies of system center position in Jan.are more evident than that in Jul.(4) The variations of mean temperature at mid-stratosphere in the vicinity of pole zone in Jan.are different from that in Jul.,but they are synchronal with the corresponding P and not significant correlation with the trend of global warming.However,the relationship between P and total O3 in Jul.are obvious.(5) There is so notable correlation between P and AO that P can represent AO.

Health Problem and Occupational Stress among Chinese Doctors

This paper provides an overview of research into mental health problem and occupational stress among Chinese doctors in recent 10 years. It indicates that doctors in general hospitals have worse mental status. Occupational stress comes from over workload, high demanding from patients, occupational risk, effort-reward imbalance and fierce competition for job promotion. For medical staffs battling against severe acute respiratory syndrome (SARS), or working in catastrophic Wenchuan earthquake-affected areas, they have elevated stress and worrying levels of psychological distress. Post-traumatic stress disorder (PTSD) is a common mental health problem among them. The most common diseases the Chinese doctors usually suffered were cervical spondylosis, hyperlipidemia, hypertension, fatty liver and hyperglycemia. It could be important for health administrators to note that mental health appears to be an?increasing problem in Chinese doctors and corresponding helping measure should be made.

构建青少年化学科普活动内容分级素材库

在收集和分析常见化学类科普素材的基础上,通过整合素材内容与科学教育体系的对应关系,为化学教育和化学科普工作者搭建一个有实践参考价值的内容分级素材库。本研究着眼新时期社会发展的政策导向和现实需求,旨在为青少年化学类科普活动的具体实践提供一种框架性和建设性的新视角。

低浓度胰蛋白酶原代培养大鼠血管内皮细胞实验方法研究

目的:探索改进一种简单、经济和高纯度的大鼠血管内皮细胞分离培养方法。方法:采用2%戊巴比妥钠麻醉Wistar大鼠,在无菌条件下截取主动脉约3~4 cm,再将主动脉血管外翻使内膜暴露,用丝线结扎动脉两端,以0.125%胰蛋白酶消化18~20 min,在倒置相差显微镜下直接观察细胞生长和细胞形态特征,分别应用免疫组化和免疫荧光方法检测第VIII因子相关抗原抗体结合情况,对培养传代的血管内皮细胞进行鉴定。结果:采用0.125%胰蛋白酶直接消化可获得高纯度的大鼠主动脉血管内皮细胞。经过3~4天培养,细胞呈集落样散在分布于六孔培养板底,到10~12天时,细胞贴壁增长至覆盖大部分培养板底,约85%的细胞汇合成单层,呈现典型的“鹅卵石”样内皮细胞特征;此外,免疫组化和免疫荧光方法检测第VIII因子相关抗原抗体结合情况,发现大多数细胞胞浆呈现棕黄色和绿色荧光的阳性反应,显示分离培养的细胞主要是血管内皮细胞。结论:本改良的细胞培养方法操作简便,只需浓度低至0.125%胰蛋白酶即可获取较高纯度的血管内皮细胞,不需要较昂贵的胶原酶及内皮细胞生长因子,与现有的其他培养方法相比更为经济实用。

Geographic range size patterns across plants and animals of Xinjiang,China

Patterns in species geographic range size are relatively well-known for vertebrates,but still poorly known for plants.Contrasts of these patterns between groups have rarely been investigated.With a detailed flora and fauna distribution database of Xinjiang,China,we used regression methods,redundancy analysis and random forests to explore the relationship of environment and body size with the geographic range size of plants,mammals and birds in Xinjiang and contrast these patterns between plants and animals.We found positive correlations between species range size and body size.The range size of plants was more influenced by water variables,while that of mammals and birds was largely influenced by temperature variables.The productivity variable,i.e.,Enhanced Vegetation Index(EVI)was far more correlated with range size than climatic variables for both plants and animals,suggesting that vegetation productivity inferred from remote sensing data may be a good predictor of species range size for both plants and animals.

Red list assessments of Chinese higher plants

Based on the two most recent assessments of Chinese higher plants in 2013 and 2020,of 34,450 and 39,330 species,respectively,we analysed the threatened status of Chinese higher plants.In 2020,around 4,088(10.39%)of the assessed species in China are threatened,2,875(7.31%)Near Threatened,27,593(70.16%)not currently threatened and categorised as Least Concern and 4,752(12.08%)categorised as Data Deficient.While in 2013,3,767(10.93%)of the assessed higher plants in China are threatened,2,723(7.90%)Near Threatened,24,296(70.53%)Least Concern and 3,612(10.48%)Data Deficient.Estimates of the Red List Index in the two years show different patterns when using different weighting methods with the equal steps weighting method showing a slight decrease(0.91675-0.91495)and the extinction risk weighting method showing a slight increase(0.98792-0.98797).We inferred that China's threatened plant species were likely/relatively effectively protected.However,attention should also be given to the non-threatened species in the future as an additional strategy for their conservation,to maintain their non-threatened status.