Ti、Zr和Hf元素协同优化Nb-Si基合金显微组织、相组成和室温断裂韧性

采用真空电弧熔炼制备Nb-16Si-xTi-yZr-zHf (x=18, 22;y=0, 4;z=0, 4;摩尔分数,%)合金并研究Ti、Zr与Hf元素对Nb-Si合金物相组成、显微组织、断裂韧性以及裂纹扩展行为的影响。结果表明:单独添加4%Zr元素能促进(Nb,X)3Si向Nb固溶体(Nbss)/γ-(Nb,X)5Si3共析反应的发生;同时添加Ti、Zr、Hf元素能进一步促进共析反应的发生。裂纹倾向于在(Nb,X)3Si中扩展,当裂纹途径Nb固溶体时会发生偏转。细密的Nbss/γ-(Nb,X)5Si3共晶组织以及层状Nbss/γ-(Nb,X)5Si3共晶组织可以使裂纹产生桥接与分支,阻碍裂纹的扩展。Nb-16Si-22Ti-4Zr-4Hf的合金化元素含量最高,因此,其室温断裂韧性最好(11.62 MPa·m1/2),相较于Nb-16Si-18Ti提高87.7%,性能的提升主要归因于存在层状共晶组织。

废三元锂离子电池正极材料脱锂渣的淀粉还原浸出动力学

以淀粉为还原剂从废三元锂离子电池(LIBs)正极材料脱锂渣中回收Ni、Co和Mn,并研究其浸出动力学和机理。系统地研究搅拌速率、浸出温度、H_(2)SO_(4)浓度和淀粉用量对Ni、Co和Mn浸出率的影响。结果表明,在搅拌速率为500 r/min、硫酸浓度为1.5 mol/L、淀粉用量为6 g/L、浸出温度为80℃和浸出时间为60 min的优化条件下,Ni、Co和Mn的浸出率分别达到98.07%、96.52%和98.06%。根据冶金过程液固反应动力学模型,脱锂渣的浸出动力学可以用化学反应控制的未反应收缩核模型很好地进行描述。在浸出反应中,Ni、Co和Mn的表观反应活化能分别为93.32、102.84和95.68 k J/mol,H_(2)SO_(4)的表观反应级数分别为0.9225、1.0335和1.1285。淀粉容易制取、成本低,可取代传统还原剂用于从废三元锂电池中提取有价金属。

Discovery of the oldest(ca.2.87 Ga)granitic gneisses in the Qinling-Dabie Orogenic Belt:Direct evidence of Mesoarchean crust

1.Objectives Precambrian microcontinents(terranes)or continental fragments are generally essential components in the evolution and architecture of Phanerozoic orogenic belts.Formation of the Qinling-Dabie Orogenic Belt,a typical Paleozoic to Triassic collisional zone between the South China Block(including the Yangtze Block and the Cathaysia Block)and the North China Block(inset map in Fig.1a),is characterized by the occurrence of several Precambrian complexes or microcontinents.

Estimated prevalence and sociodemographic correlates of mental disorders in medical students of Hebei Province,China:A crosssectional study

BACKGROUND In China,the identification rate and treatment rate of mental disorders are low,and there are few surveys on the prevalence of mental disorders among college students using diagnostic tools such as Mini-International Neuropsychiatric Interview(MINI),so the prevalence and treatment of mental disorders among college students are unclear.AIM To estimate prevalence of mental disorders among medical students in Hebei Province,and provide guidance for improving their mental health.METHODS This was a cross-sectional study based on an Internet-based survey.Three levels of medical students in Hebei Province were randomly selected(by cluster sampling)for screening.Using the information network assessment system,the subjects scanned the 2D code with their mobile phones,clicked to sign the informed consent,and answered a scale.A self-designed general status questionnaire was used to collect information about age,gender,ethnicity,grade,and origin of students.The MINI 5.0.was used to investigate mental disorders.Data analysis was performed with SPSS software.Statistically significant findings were determined using a two-tailed P value of 0.05.RESULTS A total of 7117 subjects completed the survey between October 11 and November 7,2021.The estimated prevalence of any mental disorders within 12 mo was 7.4%.Mood disorders were the most common category(4.3%),followed by anxiety disorders(3.9%);15.0%had been to psychological counseling,while only 5.7%had been to a psychiatric consultation,and only 10%had received drug therapy in the past 12 mo.CONCLUSION Although the estimated prevalence of mental disorders in medical students is lower than in the general population,the rate of adequate treatment is low.We determined that improving the mental health of medical students is an urgent matter.

Huangqi Guizhi Wuwu Decoction for treating diabetic peripheral neuropathy：a meta-analysis of 16 randomized controlled trials

OBJECTIVE:This meta-analysis was performed to systematically assess the efficacy and safety of the Chinese herbal medicine Huangqi Guizhi Wuwu Decoction(HGWWD) for treating diabetic peripheral neuropathy.DATA SOURCES:Six electronic databases,including the Cochrane Library,MEDLINE database,Chinese Biomedical Database,Chinese National Knowledge Infrastructure Database,Chinese Science and Technique Journals Database,and the Wanfang Database,were search ed on the internet for randomized controlled trials published up until 1 December 2015.The search terms included "Chinese herbal medicine","diabetic peripheral neuropathy" and "randomized controlled trials" in Chinese and in English.DATA SELECTION:We included randomized controlled trials using HGWWD/modified HGWWD for the treatment group,without restriction for the control group.We assessed literature quality in accordance with the Cochrane Review Handbook.A random or a fixed effects model was used to analyze outcomes using Rev Man 5.2 software.OUTCOME MEASURES:The primary outcomes were changes in symptoms and nerve conduction velocities.The secondary outcomeswere fasting blood glucose and hemorheological indexes.RESULTS:Sixteen randomized controlled trials,with a total of 1,173 patients,were included.Meta-analysis revealed that the efficacy of HGWWD for diabetic peripheral neuropathy was significantly superior compared with the control treatment(i.e.,control group)(risk ratio = 0.36,95% confidence interval(CI):0.29–0.46,Z =8.33,P < 0.00001) Compared with the control group,there was an increase in median motor nerve conduction velocity(mean difference(MD) = 3.46,95%CI:1.88–5.04,Z = 4.30,P < 0.01) and median sensory nerve conduction velocity(MD = 3.30,95%CI:2.04–4.56,Z = 5.14,P < 0.01).There was also an increase in peroneal motor nerve conduction velocity(MD = 3.22,95%CI:2.45–3.98,Z = 8.21,P < 0.01) and peroneal sensory nerve conduction velocity(MD = 3.05,95%CI:2.01–4.09,Z = 5.75,P < 0.01) in the treatment groups.No significant difference in fasting blood glucose was found between the treatment groups and the control groups(MD =-0.12,95%CI:-0.42–0.19,Z = 0.76,P = 0.45).Plasma viscosity was significantly decreased after treatment(MD =-0.11,95%CI:-0.21 to-0.02,Z = 2.30,P = 0.02).No significant difference in fibrinogen was detectable(MD =-0.53,95%CI:-1.28–0.22,Z = 1.38,P = 0.17).Four trials reported that treatment groups experienced no adverse reactions.Adverse events were not mentioned in the other 12 trials.No trial reported the incidence of complications,quality of life outcomes,or health economics.CONCLUSION:HGWWD treatment improves diabetic neurologic symptoms and ameliorates nerve conduction velocities.Our study suggests that HGWWD may have significant therapeutic efficacy for the treatment of diabetic peripheral neuropathy.However,the methodological quality of the randomized controlled trials was generally low.Larger and better-designed randomized controlled trials are required to more reliably assess the clinical effectiveness of HGWWD.

Energy-saving Technology of Vent in Passive Solar Wall of Rural House of Severe Cold Region

This paper aims at solving the problems of low thermal collection rate,inconvenient maintenance,hindering indoor using during the application of passive solar technologies in rural houses in severe cold region.All these defects prevent the passive solar houses' further development. This paper chooses trombe wall,which has higher thermal efficiency of the passive solar house,as research object. The traditional vent is improved into a new type of ventilation device. This improvement overcomes the shortcoming,which traditional vent loses huge heat,and simplifies the construction of vent. Comparing with traditional trombe wall,the energy saving rate is 15. 69%.

An Exercise Collection Auto-Assembling Framework with Knowledge Tracing and Reinforcement Learning

In educational practice,teachers often need to manually assemble an exercise collection as a class quiz or a homework assignment.A well-assembled exercise collection needs to have the proper difficulty index and discrimination index so that it can better develop students'abilities.In this paper,we propose an exercise collection auto-assembling framework,in which a teacher provides the target values of difficulty and discrimination indices and a qualified exercise collection is automatically assembled.The framework consists of two stages.At the answer prediction stage,a knowledge tracing model is utilized to predict the students'answers to unseen exercises based on their history interaction records.In addition,to better represent the exercises in the model,we propose exercise embeddings and design a pre-training approach.At the collection assembling stage,we propose a deep reinforcement learning model to assemble the required exercise collection effectively.Since the knowledge tracing model in the first stage has different confidences in the predicted answers,it is also taken into account in the objective.Experimental results show the effectiveness and efficiency of the proposed framework.

Correspondence:Thermal strain response of saturated clays in 1D condition

1 Introduction In recent years the thermomechanical behavior of soils has attracted more attention due to an increasing number of geotechnical practices involving thermal effects (Bourne-Webb et al,2013;Olgun et al.,2014;Loria et al,2018;Peng et al.,2018;Pinyol et al.,2018;Kaddouri et al.,2019;Mu et al.,2019).