基于四象限模型煤粮复合区景观生态质量时空变化及影响因素

在煤粮复合区,煤炭开采通过影响区域的景观格局,不断地冲击着原有农业景观生态系统的功能和过程,对该区域的景观生态质量及其影响因素进行分析对于矿区生态治理具有重要的理论意义和实践价值。该研究以河南省辉县市赵固煤矿为例,以行政村为评价单元,采用四象限模型对研究区景观生态质量进行了综合评价。结果表明:1)受煤炭开采活动和土地生态整治的影响,2008—2016年,研究区耕地面积总体上呈现先减少后增加的变化趋势,耕地主要向建设用地和水域转移。建设用地呈现先增加后减少的变化趋势,建设用地主要向水域和耕地转移。2)研究区的景观稳定性指数呈现先减少后增加的变化趋势,而景观干扰性指数呈现先增加后减少的变化特征。3)研究区景观生态质量在时间尺度上呈现“良好—较差—较好”的变化特征。2008年,矿井建设及开采初期研究区景观生态质量整体上较好。随着开采活动增强,到2011年研究区景观干扰程度增加和稳定程度降低,造成区域景观生态质量下降。2014年后大规模土地复垦使研究区土地利用率增加,大面积沉陷水域改善了区域景观结构,景观系统稳定性增加。4)在空间尺度上,受开采活动和土地生态整治的影响,矿区采点附近村庄景观生态质量呈现先变差后好转的变化趋势,远离矿区开采点的村庄有略微变差的趋势。总体上,与2011年相比,2016年质量为优的村庄数量和面积增加,质量为差的村庄数量和面积减少,但与2008年相比,2016年质量为优的村庄数量和面积仍是减少,质量为差的区域的村庄数量和面积仍是增加,表明研究区景观生态质量虽有所改善,但仍未恢复到受扰动前的景观生态质量水平。

人造石矽肺文献病例分析

为降低我国人造石矽肺发病率,分析文献病例作业场所人造石成分、接触机会、临床特征、流行病学特点,并提出预防人造石矽肺的发生应采取湿式作业、通风除尘、个体防护等综合措施。结果表明:作业场所干式作业、结晶型二氧化硅质量浓度超标,无通风除尘、个体防护措施是引起人造石矽肺的主要原因。2010—2019年,西班牙、以色列、意大利、美国、澳大利亚和我国分别报道了本国人造石矽肺病例,共计131例。随着人造石的大量生产加工和使用,病例数也在不断增加。文献病例多集中在30~50岁,工龄在10年以上,且均为男性。很多病例早期无明显自觉症状。随着病情进展,或有合并症时,可出现咳嗽、咳痰、胸闷、气短、胸痛等症状。有时临床特征与X线胸片改变不一致。工作场所人造石中结晶型二氧化硅含量均在70%以上,粉尘质量浓度均超过其本国的职业接触限值。工作时多采用干式切割,无通风除尘等防尘措施,且大多没有佩戴合格的呼吸防护用品。

不同层理煤破坏过程声发射RA-AF特征研究

为研究不同层理煤破坏声发射RA-AF特征,开展了0°、30°、60°、90°层理夹角煤单轴压缩破坏试验,同步采集了煤体力学和声发射数据,分析了RA-AF特征与裂纹扩展模式的关系。结果表明:第Ⅰ和第Ⅱ阶段,声发射计数水平较低,第Ⅲ阶段,计数值逐渐增加,在第Ⅳ阶段,α=0°和60°时,声发射计数更多,峰值较高;α=0°和90°时,张拉破坏占比分别为58.44%和58.06%,裂纹以张拉破坏为主;α=30°时,张拉剪切破坏占比相当,裂纹表现为张剪复合破坏;α=60°时,试样剪切破坏占比68.14%,裂纹以剪切破坏为主。

单层FeSe薄膜/氧化物界面高温超导

单层FeSe/SrTiO_3界面增强超导的发现为理解高温超导机理提供了一个新的途径,也为实现新的高温超导体开拓了新思路.本文通过在SrTiO_3(001)表面高温沉积Mg进而沉积单层FeSe薄膜,制备出了FeSe/MgO双层/SrTiO_3异质结.利用扫描隧道显微镜研究了异质结的电学及超导特性,观测到约14-15 meV的超导能隙,比体相FeSe超导能隙值增大了5—6倍,与K掺杂双层FeSe/SrTiO_3的超导能隙值相当.这一结果可理解为能带弯曲造成的界面电荷转移和界面处电声耦合共同作用导致的超导增强.FeSe/MgO界面是继FeSe/TiO_2之后的一个新界面超导体系,为研究界面高温超导机理提供了新载体.

Improved wettability and mechanical properties of metal coated carbon fiber-reinforced aluminum matrix composites by squeeze melt infiltration technique

In order to improve the wettability and bonding performance of the interface between carbon fiber and aluminum matrix,nickel-and copper-coated carbon fiber-reinforced aluminum matrix composites were fabricated by the squeeze melt infiltration technique.The interface wettability,microstructure and mechanical properties of the composites were compared and investigated.Compared with the uncoated fiber-reinforced aluminum matrix composite,the microstructure analysis indicated that the coatings significantly improved the wettability and effectively inhibited the interface reaction between carbon fiber and aluminum matrix during the process.Under the same processing condition,aluminum melt was easy to infiltrate into the copper-coated fiber bundles.Furthermore,the inhibited interface reaction was more conducive to maintain the original strength of fiber and improve the fiber−matrix interface bonding performance.The mechanical properties were evaluated by uniaxial tensile test.The yield strength,ultimate tensile strength and elastic modulus of the copper-coated carbon fiber-reinforced aluminum matrix composite were about 124 MPa,140 MPa and 82 GPa,respectively.In the case of nickel-coated carbon fiber-reinforced aluminum matrix composite,the yield strength,ultimate tensile strength and elastic modulus were about 60 MPa,70 MPa and 79 GPa,respectively.The excellent mechanical properties for copper-coated fiber-reinforced composites are attributed to better compactness of the matrix and better fiber−matrix interface bonding,which favor the load transfer ability from aluminam matrix to carbon fiber under the loading state,giving full play to the bearing role of carbon fiber.

Numerical simulation of airflow distribution in mine tunnels

Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels is studied. The average velocity points were analyzed quantitatively. The results show that the airflow pattern is similar for the three-center arch section under different ventilation velocities and cross sectional areas. The shape of the tunnel cross section and wall are the critical factors influencing the airflow pattern. The average velocity points are mainly close to the tunnel wall. Characteristic equations are developed to describe the average velocity distribution, and provide a theoretical basis for accurately measuring the average velocity in mine tunnels.

A movement-assisted software-defined sensor network with NFV support

A flexible and controllable movement-assisted software-defined sensor network(MA-SDSN)based on the software-defined network(SDN)and network function virtualization(NFV)is proposed.First,a three-layer fundamental architecture is proposed to overcome the inherent distributed management and rigidity of the conventional wireless sensor networks.Furthermore,the platform for research and development of MA-SDSN is established,and the dumb node(DN),the software-defined node(SN)and the movement-assisted node(MN)are designed and implemented.Then,the southbound application programming interface(API)is designed to provide a series of frames for communication between controllers and sensor nodes.The northbound API is developed and demonstrated overall and in detail.The functions of the controller are presented including topology discovery,dynamic networking,packet processing,mobility management and virtualization.Followed by the MA-SDSN network model,a Markov chain-based movement-assisted weighted relocation(MMWR)topology control algorithm is proposed to redeploy the MNs based on the node status and weight.Simulation results and analysis indicate that the proposed algorithm based on the MA-SDSN extends network lifetime with a lower average power consumption.

A novel model of drug cue-induced behaviours in rhesus macaque subjected to chronic ketamine exposure

To the Editor,Non-human primate(NHP)models are advantageous for mimicking human addiction with high behavioural validity.1 However,current NHP drug addiction models(eg,self-administration)often require a comprehensive behavioural training paradigm,relatively expensive apparatus and invasive surgical procedures.

大气风速对深凹露天矿山炮烟排烟时间的影响研究

为探究大气风速对深凹露天矿山爆破排烟时间的影响,采用CFD数值模拟方法构建了深凹露天矿山爆破非稳态数值模型,模拟大气风速为3、6、9、15 m/s和不同爆破位置条件下炮烟扩散场景,研究了不同大气风速对深凹露天采坑内风流场特征和爆破排烟时间的影响。研究结果表明:不同爆破位置下,随着大气风速的增大,露天采坑内的风流分布呈现出单复环流向双复环流结构的转变;当大气风速大于6 m/s后,随着大气风速的增大,爆破炮烟排烟时间下降的幅度逐渐减小,大气风速对排烟时间的影响逐渐降低;不同爆破位置下,随着大气风速的增大,露天采坑爆破炮烟排烟时间均呈现下降趋势,且与大气风速呈现良好的指数函数关系。

可有效利用大尺度空间的蜂巢式空间分隔构件

大尺度空间在带给人们宽阔透亮的视觉感受的同时,也会带来一些不可避免的空间浪费,空间分隔方法可以对空间进行有效利用。研究将蜂巢作为仿生对象,结合其特点和空间结构,创建蜂巢式空间分隔构件。蜂巢式空间分隔构件既能满足不同的功能需求,又能做到造型美观、材质环保,在人流密集时可以做到人员分流、隔离,提高结构安全性。适用于对高校图书馆、食堂等大尺度公共空间进行进一步改造,从而打造一个令人方便、舒适的环境。

Stress-relevant social behaviors of middle-class male cynomolgus monkeys （Macaca fascicularis）

Stress from dominance ranks in human societies, or that of other social animals, especially nonhuman primates, can have negative influences on health. Individuals holding different social status may be burdened with various stress levels. The middle class experiences a special stress situation within the dominance hierarchy due to its position between the higher and lower classes. Behaviorally, questions about where middle-class stress comes from and how individuals adapt to middle-class stress remain poorly understood in nonhuman primates. In the present study, social interactions, including aggression, avoidance, grooming and mounting behaviors, between beta males, as well as among group members holding higher or lower social status, were analyzed in captive male-only cynomolgus monkey groups. We found that aggressive tension from the higher hierarchy members was the main origin of stress for middle- class individuals. However, behaviors such as attacking lower hierarchy members immediately after being the recipient of aggression, as well as increased avoidance, grooming and mounting toward both higher and lower hierarchy members helped alleviate middle-class stress and were particular adaptations to middle-class social status.

爆破位置对深凹露天矿山炮烟扩散影响的数值模拟研究

深凹露天矿山结构特殊,导致爆破产生的炮烟扩散稀释较为困难,严重危害生产作业人员的生命安全与健康。基于实际矿山构建了深凹露天矿山的二维物理及数学模型,采用非稳态数值分析方法研究了不同爆破位置下深凹露天矿山采坑内爆破炮烟的扩散规律。研究结果表明:不同爆破位置下,露天采坑内均出现复环流,爆破点位置是影响露天采坑内风流结构特征的重要因素;露天采坑内的炮烟最高浓度均随着时间变化而逐渐下降,但下降的速率逐步减小,呈现三个阶段的下降趋势;爆破位置位于背风侧时,露天采坑内的炮烟最高浓度和降至安全浓度所需时间远高于迎风侧三个爆破位置;随着背风侧爆破点与采坑底部距离的缩短,炮烟最高浓度及降至安全浓度所需时间先降低后增加,炮烟最高浓度和降至安全浓度所需时间随着迎风侧爆破位置与采坑底部距离的缩短而增加。研究结果对于指导深凹露天矿山企业合理组织爆破后的生产作业和保障作业人员安全具有重要意义。

酸性矿山废水对稻田土壤微生物菌群结构的影响

为探究酸性矿山废水(AMD)对稻田土壤微生物群落结构的影响,通过取自矿区受AMD污染和未受污染的稻田土壤进行微宇宙灌溉模拟实验,研究了AMD污染过程中土壤理化性质和微生物群落的变化,同时建立环境条件变化引起土壤微生物群落结构改变的相关性关系.结果表明,受AMD污染的土壤中SO4^2-、Cd、Zn含量显著上升,土壤酸化且土壤中细菌群落的多样性下降;而恢复清洁水灌溉可提高土壤细菌群落的多样性,有利于修复AMD的污染.采用高通量测序技术分析了不同处理稻田土壤中微生物群落在门和属分类水平上的相对丰度分布变化,冗余分析(RDA)表明,土壤pH和重金属(Pb、Cu)含量是影响稻田土壤微生物群落结构的主要环境因子.研究结果不仅有助于进一步揭示AMD污染、土壤因子与土壤微生物群落的相互关系,同时可为恢复AMD污染农业土壤提供理论依据.

Diluted ferromagnetic semiconductor(LaCa)(ZnMn)SbO isostructural to “1111” type iron pnictide superconductors

We report discovery of ferromagnetism in(LaCa)(ZnMn)SbO isostructural to the well-studied iron-based superconductor LaFeAs(O1 xFx).Spin is induced by partial substitution of Mn2+for Zn2+,while charge is induced by substitution of Ca2+for La3+within the parent compound LaZnSbO.Ferromagnetism with Curie temperature(TC)is observed up to 40 K at the spin doping 0.15 by introducing Mn2+into the Zn2+sites for(La0.95Ca0.05)(Zn1 xMnx)SbO.The Hall coefficient measurement indicates p-type carrier for(La0.95Ca0.05)(Zn0.9Mn0.1)SbO with concentration of n^1020cm 3showing anomalous Hall effect below TC.

不同国家室内装修工人的人造石矽肺发病情况

本文对来自以色列、西班牙、美国、意大利、澳大利亚的177例室内装修工人人造石矽肺病例的健康状况及作业场所防尘措施等进行分析。室内装修工人都来自小型企业(或作坊),从事厨房和/或浴室人造石台面切割、研磨、抛光等再加工。工作环境中人造石结晶型二氧化硅含量均在70%以上,矽尘浓度超过相关标准。多数作业场所采用干式切割,无通风除尘等防尘措施,工人大多没有佩戴合格的呼吸防护用品。采取湿式作业、通风除尘、个体防护等综合措施,可以有效地预防人造石矽肺的发生。

Prefrontal dysfunction and a monkey model of schizophrenia

The prefrontal cortex is implicated in cognitive functioning and schizophrenia. Prefrontal dysfunction is closely associated with the symptoms of schizophrenia. In addition to the features typical of schizophrenia, patients also present with aspects of cognitive disorders. Based on these relationships, a monkey model mimicking the cognitive symptoms of schizophrenia has been made using treatment with the non-specific competitive N-methyI-D-aspartate receptor antagonist, phencyclidine. The symptoms are ameliorated by atypical antipsychotic drugs such as clozapine. The beneficial effects of clozapine on behavioral .impairment might be a specific indicator of schizophrenia-related cognitive impairment.

Influence of Coal Nature and Structure on Ash Size Formation Characteristic and Related Pollutant Emissions During CFB Combustion

The size distribution of coal particles in a Circulating Fluidized Bed (CFB) boiler plays a crucial role in the complicated combustion, heat exchange and pollutant emissions in such a plat. Therefore, it is fundamental to study the different factors having influence on the size distribution of coal particles. Above all, the coal itself and in particular, the coal combination phenomenon is a very influent factor. In the frame of this work, the coal nature (elementary composition) and coal internal structure (mineral components) are studied in detail. At this intermediary stage, experiments on three typical Chinese coals on a l.5 MWt CFBC pilot plant have been made. Some primary fragmentation tests have also been made in a small lab scale fluidized bed reactor. The results from the hot pilot test show i) the variation of coal ash distributions and other CFB performance data due to the cyclone and the coal characteristics and ii) the variation of desulfurization efficiency with limestone. Whereas the bench scale primary fragmentation test, likely linked to the caking propriety of a coal, does not seem to change considerably the char size distribution.