Controlling dispersion and morphology of MoS2 nanospheres by hydrothermal method using SiO2 as template

Monodispersed MoS_2 nanospheres were successfully synthesized by using SiO_2 as hard template. The size and morphology of the MoS_2 nanospheres could be finely controlled by the content of SiO_2 and sulfur precursors. Furthermore, higher surface area of monodispersed MoS_2 nanospheres exhibited high reaction rate for hydrodesulfurization(HDS) of dibenzenethiophene(DBT).

Pyrrolic N or pyridinic N: The active center of N-doped carbon for CO_(2) reduction

Pyridinic N is widely regarded as the active center while pyrrolic N has low‐activity in metal‐free N‐doped carbon for electrocatalytic CO_(2) reduction reaction(CO_(2)RR)to CO,but this viewpoint remains open to question.In this study,through density functional theoretical calculations,we first illustrate that the intrinsic activity of pyrrolic N is high enough for effectively catalyzing CO_(2)RR,however,due to the interplay with the neighboring pyridinic N sites,the activity of pyrrolic N is dramatically suppressed.Then,experimentally,metal‐free N‐doped carbon spheres(NCS)electrocatalysts without significant pyridinic N content are prepared for CO_(2)RR.The pyrrolic N in NCS shows a direct‐positive correlation with the performance for CO_(2)RR,representing the active center with high activity.The optimum NCS could produce syngas with a wide range of CO/H_(2) ratio(0.09 to 12)in CO_(2)RR depending on the applied potential,meanwhile,the best selectivity of 71%for CO can be obtained.Intentionally adding a small amount of pyridinic N to the optimum NCS dramatically decreases the activity for CO_(2)RR,further verifying the suppressed activity of pyrrolic N sites by the neighboring pyridinic N sites.This work reveals the interaction between a variety of N species in N‐doped carbon,and the potential of pyrrolic N as the new type of active site for electrocatalysts,which can improve our understanding of the electrocatalysis mechanism and be helpful for the rational design of high‐efficient electrocatalysts.

Application of the fractal theory for evaluating effects of coal comminution by waterjet

Comminution of coal to ultrafine sizes by high-pressure waterjet provides a novel method for preparation of coal-water fuels for next generation,near-zero emission electric power generation.The particle size distribution(PSD)of ground coal is a key parameter in the preparation of slurries as it determines the settling behavior of the particles and viscosity of the coal-water mixture.There are several methods available for representation and evaluation of particle size analysis data.However,fractal theory provides a means by which the entire PSD of comminuted materials can be quantified by using of a specific and exact value.In this paper,a volume-based fractal model was deduced to characterize the PSD of the coal which is ground in a specially designed comminution cell.During the size reduction process,the inlet pressures up to 276 MPa were used.

Drag of a D-shaped bluff body under small amplitude harmonic actuation

Open-loop flow control method was used to affect the development of a turbulent wake behind a D-shaped bluff body. Loud speakers were embedded inside the bluff body to produce two zero-net-mass- flux jets through 2 mm-wide span-wise slots located along the upper and lower edges on the rear wall. The drag forces for different actuation amplitudes （Cμ, the ratio between the momentum of the actuating jets and the moment deficit caused by the bluff body） and frequencies （StA） were examined. The effects of the phase difference in the two jets （0 and π） were also studied. It was found that when Cμ was 0.1%, a drag reduction up to 5% was achieved when the velocities of the two jets varied in phase at a frequency of 5tA = 0.16. When the velocities of the two jets varied π out of phase, significant drag increase was observed.

企业人力资源管理中的薪酬管理创新路径研究

薪酬管理是企业人力资源管理的重要组成部分,直接影响员工的工作积极性、组织效率以及公司竞争力。随着经济环境和市场条件的不断变化,传统薪酬管理模式也逐渐显露出其局限性。本文首先通过分析企业薪酬管理理念的发展,进而针对其对于企业发展的作用做出论述,指出当下企业薪酬管理中存在的问题并对其提出具有针对性的解决措施,旨在为企业提供改进薪酬管理的实践指导和理论支持。

医疗保险干预能否缓解三级医院的“虹吸效应”?——基于某大城市的实证研究

【问题】患者普遍偏好在三级医院就诊,而三级医院对患者的“虹吸效应”直接影响了医疗服务体系的运行效率。差异化报销的医保政策干预成为各地推行“分级诊疗”的普遍手段。虽然三级医院的“虹吸效应”已经得到学界的普遍关注,成为医改领域的热点研究问题,但现有相关研究还主要停留在理论探讨层面。而且,医保政策干预作为分级诊疗推动措施究竟能够发挥多大作用,在实证方面还缺乏足够的文献支持。【方法】文章基于A市的医疗保险数据,使用固定效应等研究方法,对三级医院的“虹吸效应”和医保政策干预效果进行了分析。【发现】三级医院对使用社会医疗保险患者的门诊就医选择有“虹吸效应”,每10万人配备的三级医院数量每增加1家,赴三级医院门诊就医的患者比例就提高5.8%。“虹吸”的主要对象来自二级医院而非一级及以下医疗机构的患者群体。“虹吸效应”存在异质性:无慢性病群体、高收入者、儿童更容易被三级医院“虹吸”。医保政策干预能够缓解“虹吸效应”,且对“小病、常见病”的影响程度更大,可以有效引导把价格敏感的患者向基层医院分流。【贡献】文章从实证上检验了三级医院对需求方的“虹吸效应”及其程度,首次揭示了中国二级医院的“夹心层”困境;通过检验医保政策干预对“虹吸效应”的效果,为医保补偿政策推动分级诊疗提供了新的经验证据。文章对于推动分级诊疗、优化医疗资源配置具有重要的现实意义。

Effects of pyrite on the spontaneous combustion of coal

Abstract Pyrite has a significant effect on the spontaneous combustion of coal. The presence of pyrite can change the propensity of coal towards spontaneous combustion. The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc., were investigated in this study, Coal samples with different pyrite contents （0 %, 3 %, 5 %, 7 % and 9 %） were made by mixing coal and pyrite. The oxidation experiments under temperature-programmed condition were carried out to test the release rate of gaseous oxidation products at different temperatures. Differential scanning calorimeter （DSC） was employed to measure the intensity of heat release during coal oxidation for various pyrite contents. The results indicate that pyrite can nonlinearly accelerate the process of spontaneous combustion. The coal sample with a pyrite content of 5 % has the largest CO release rate and oxygen adsorption as well. However, the coal sample with a pyrite content of ？ % has the largest rate of heat flow according to the results from the DSC tests. Pyrite contents of 5 %-7 % in coal has the most significant effects on spontaneous combustion within the range of this study. The conclusions are conducive to the evaluation and control for the spontaneous combustion of coal.

看电视时间与婴幼儿语言、情绪社会性发展的关系——一项追踪研究

采用追踪设计,利用家庭基本情况调查表调查婴幼儿14～25个月的电视接触时长,利用《汉语沟通发展量表》和《婴幼儿社会-情绪性量表》评估婴幼儿14～25个月语言发展及情绪社会性发展,由此考察看电视时间与婴幼儿语言以及情绪社会性发展的关系,结果发现:(1)在看电视时间与儿童语言发展方面,婴幼儿14个月时,不看电视和看电视30分钟的婴幼儿比看电视超过60分钟的婴幼儿在短语理解上的表现相对更好;每天看电视30分钟的婴幼儿比不看电视和看电视超过60分钟的婴幼儿在动作和手势方面的表现相对更好。在婴幼儿25个月时,没有发现看电视时间长短与此年龄阶段语言发展的相关;14个月婴幼儿看电视时间与其25个月语言发展也没有关系。(2)在看电视时间与情绪社会性发展方面,在婴幼儿14个月时,每天不看电视和看电视30分钟的婴幼儿比看电视15分钟以内的婴幼儿在能力域和掌握动机上表现更好,并且这两组分别在能力域和掌握动机上比看电视超过60分钟的婴幼儿表现更好。在婴幼儿25个月时,不看电视的婴幼儿比看30分钟以内和看电视超过60分钟的婴幼儿在注意力方面表现更好;看电视不超过60分钟的婴幼儿比每天看电视超过60分钟的婴幼儿在亲社会同伴关系中拥有更好的表现。看电视时间在跨年龄段的比较结果显示,每天不看电视的婴幼儿有更多的同伴攻击行为,但不看电视的婴幼儿比看电视15分钟以内以及看电视超过60分钟的婴幼儿注意力表现更好;看电视在15分钟以内的婴幼儿拥有最多的内隐行为问题和焦虑行为;看电视30分钟的婴幼儿比看电视15分钟以内和超过60分钟的婴幼儿在能力域和注意力方面表现更好,且该组婴幼儿比其他组的婴幼儿拥有更好的移情能力。婴幼儿看电视时间对其语言和情绪社会性发展的影响有利有弊,需要家长高度重视,采用合理的方式积极引导婴幼儿养成良好的看电视习惯,从而促进其语言和情绪社会性等方面的健康发展。

A phylogeny of the Passerida(Aves: Passeriformes)based on mitochondrial 12S ribosomal RNA gene

Background: Passerida is the largest avian radiation within the order Passeriformes. Current understanding of the high-level relationships within Passerida is based on DNA–DNA hybridizations; however, the phylogenetic relationships within this assemblage have been the subject of many debates.Methods: We analyzed the 12 S ribosomal RNA gene from 49 species of Passerida, representing 14 currently recognized families, to outline the phylogenetic relationships within this group.Results: Our results identified the monophyly of the three superfamilies in Passerida: Sylvioidea, Muscicapoidea and Passeroidea. However, current delimitation of some species is at variance with our phylogeny estimate. First, the Parus major, which had been placed as a distinct clade sister to Sylvioidea was identified as a member of the super family;second, the genus Regulus was united with the Sturnidae and nested in the Muscicapoidea clade instead of being a clade of Passerida.Conclusion: Our results were consistent with Johansson's study of the three superfamilies except for the al ocation of two families, Paridae and Regulidae.

Cloning and Diversity Analysis of TaHKT2;2 in Hexaploid Wheat

In order to study the roles of members of HKT gene fanfily in wheat, TaHKT2 ; 2 was isolated by using homologous cloning strategy and screening genomic BAC library. TaHKT2; 2 genes were mapped on chromosomes 7A, 7B and 7D, named as TaHKT2; 2-7A, TaHKT2; 2-7B, and TaHKT2; 2-7D, respectively. TaHKT2 ; 2 and TaHKT2 ; 1 had the same genetic structure, composed of three exons and two introns, and formed a cluster with TaHKT2 ; 1 on the phylogenetic tree of plant HKT transporters. The coding sequences of TaHKT2 ; 2-7A, TaHKT2 ; 2-7B, and TaHKT2 ; 2-7D were 1 602, 1 602 and 1 596 bp long, respectively, but TaHKT2 ;2-7D cDNA sequence was not isolated by RT-PCR in eight wheat varieties. The natural diversity of TaHKT2 ;2 genes was analyzed by cloning and sequencing from 12 wheat varieties. The results showed that TaHKT2;2-7A was found to be more diverse than TaHKT2; 2-7B and TaHKT2; 2-7D. Only a few bases changed in the alleles of TaHKT2 ; 2 genes in wheat. No amino-acid natural variation lay in the P-loops of deduced protein sequences of all alleles of TaHKT2 ; 2 in 12 wheat varieties. The identity of coding sequences was nmch higher than that of 5＇ flanking regions of TaHKT2 ; 2 genes. TaHKT2 ; 2 nfight be selected over the comse of wheat domestication and belonged to domestication gene.

基于相关系数的水文序列滑动周期识别方法

准确进行周期识别对于合理认识水文变异规律、开展中长期水文模拟预报、水安全评价等具有重要的意义.本文通过滑动改变周期长度和初相位,构造出多组模拟周期序列,并以相关系数作为模拟周期序列与原始序列拟合精度的判别指标,选择拟合程度最好的模拟周期作为最优周期识别结果,从而提出水文序列滑动周期识别方法.理论和公式推导表明:相关系数可表征水文序列中的周期波动程度,相关系数越大,说明拟合精度越高,对应的周期变异越显著.统计试验结果显示:相比于常用的周期识别方法,文中方法的周期识别效率更高,且在各因素影响下也最具稳定性和可靠性.最后,文中方法应用于澜沧江流域21个站的年降雨量序列进行周期识别,结果显示该流域的降雨周期存在多时间尺度特征,北部和中部的降雨周期长度较短,多数在2~5 a左右,而南部的降雨周期5~10 a居多,个别站点的周期长度达到了18 a.