Theoretical insights into the effects of molar ratios on stabilities,mechanical properties,and detonation performance of CL-20/HMX cocrystal explosives by molecular dynamics simulation

To research and estimate the effects of molar ratios on structures, stabilities, mechanical properties, and detonation properties of CL-20/HMX cocrystal explosive, the CL-20/HMX cocrystal explosive models with different molar ratios were established in Materials Studio (MS). The crystal parameters, structures, stabilities, mechanical properties, and some detonation parameters of different cocrystal explosives were obtained and compared. The molecular dynamics (MD) simulation results illustrate that the molar ratios of CL-20/HMX have a direct influence on the comprehensive performance of cocrystal explosive. The hardness and rigidity of the 1:1 cocrystal explosive was the poorest, while the plastic property and ductibility were the best, thus implying that the explosive has the best mechanical properties. Besides, it has the highest binding energy, so the stability and compatibility is the best. The cocrystal explosive has better detonation performance than HMX. In a word, the 1:1 cocrystal explosive is worth more attention and further research. This paper could offer some theoretical instructions and technological support, which could help in the design of the CL-20 cocrystal explosive.     

Advanced Electro-active Dry Adhesive Actuated by an Artificial Muscle Constructed from an Ionic Polymer Metal Composite Reinforced with Nitrogen-doped Carbon Nanocages

An advanced electro-active dry adhesive,which was composed of a mushroom-shaped fibrillar dry adhesive array actuated by an Ionic Polymer Metal Composite (IPMC) artificial muscle reinforced with nitrogen-doped carbon nanocages (NCNCs),was developed to imitate the actuation of a gecko's toe.The properties of the NCNC-reinforced Nafion membrane,the electromechanical properties of the NCNC-reinforced IPMC,and the related electro-active adhesion ability were investigated.The NCNCs were uniformly dispersed in the 0.1 wt％ NCNC/Nafion membrane,and there was a seamless connection with no clear interface between the dry adhesive and the IPMC.Our 0.1 wt％ NCNC/Nafion-IPMC actuator shows a displacement and force that are 1.6-2 times higher than those of the recast Nafion-IPMC.This is due to the increased water uptake (25.39％) and tensile strength (24.5 MPa) of the specific 3D hollow NCNC-reinforced Nafion membrane,as well as interactions between the NCNCs and the sulfonated groups of the Nafion.The NCNC/Nafion-IPMC was used to effectively actuate the mushroom-shaped dry adhesive.The normal adhesion forces were 7.85 mN,12.1 mN,and 51.7 mN at sinusoidal voltages of 1.5 V,2.5 V,and 3.5 V,respectively,at 0.1 Hz.Under the bionic leg trail,the normal and shear forces were approximately 713.5 mN (159 mN·cm-2) and 1256.6 mN (279 mN·cm-2),respectively,which satisfy the required adhesion.This new electro-active dry adhesive can be applied for active,distributed actuation and flexible grip in robots.     

Three‐Stage Inter‐Orthorhombic Evolution and High Thermoelectric Performance in Ag‐Doped Nanolaminar SnSe Polycrystals

The ultrahigh thermoelectric performance of SnSe‐based single crystals has attracted considerable interest in their polycrystalline counterparts. However, the temperature‐dependent structural transition in SnSe‐based thermoelectric materials and its relationship with their thermoelectric performance are not fully investigated and understood. In this work, nanolaminar SnSe polycrystals are prepared and characterized in situ using neutron and synchrotron powder diffraction measurements at various temperatures. Rietveld refinement results indicate that there is a complete inter‐orthorhombic evolution from Pnma to Cmcm by a series of layer slips and stretches along the a‐ and b‐axes over a 200 K temperature range. This phase transition leads to drastic enhancement of the carrier concentration and phonon scattering above 600 K. Moreover, the unique nanolaminar structure effectively enhances the carrier mobility of SnSe. Their grain and layer boundaries further improve the phonon scattering. These favorable factors result in a high ZT of 1.0 at 773 K for pristine SnSe polycrystals. The thermoelectric performances of polycrystalline SnSe are further improved by p‐type and n‐type dopants (i.e., doped with Ag and SnCl₂, respectively), and new records of ZT are achieved in Ag_0.015Sn_0.985Se (ZT of 1.3 at 773 K) and SnSe_0.985Cl_0.015 (ZT of 1.1 at 773 K) polycrystals.     

闽江河口红树林土壤微生物群落对互花米草入侵的响应

采用磷脂脂肪酸标记法(PLFA)研究外来入侵植物互花米草对闽江河口湿地红树林土壤微生物群落结构的影响,并探讨其主要影响因素。结果表明:从3种不同植被群落土壤(红树林群落MC、红树林-互花米草混生群落MS、互花米草群落SC)共检测到22种PLFA生物标记,MS土壤微生物PLFA生物标记总量明显高于其他植被群落,3种植被群落土壤理化性质和酶活性的变化趋势为:MCMSSC,表明互花米草入侵后土壤微生物量增加,而理化性质和酶活性均有明显下降,红树林湿地土壤质量发生了明显退化。3种植被群落土壤中含量最高的PLFA生物标记是16:0,16:1w7c,9Me15:0w,18:1w12c。土壤中特征微生物相对生物量存在明显差异,细菌分布量最大,其次是真菌和放线菌,原生动物分布量最小。群落多样性指数呈相似规律,MS土壤微生物类群多样性指数均小于MC,表明互花米草入侵后土壤微生物群落多样性指数均有下降。通过主成分分析,基本能区分出3种不同植被群落微生物群落的特征。土壤理化性质、酶活性间存在相关性,有机碳、全氮、蔗糖酶、过氧化氢酶与革兰氏阴性菌、放线菌呈显著或极显著正相关。研究结果表明互花米草入侵在一定程度上具有影响红树林群落土壤营养代谢循环的潜力,特别是关于碳、氮、磷等的循环及酶活性,改变部分有利于自身生长的土壤环境相关的微生物类群含量,竞争有利环境,迅速扩张实现入侵。     

2001-2010年疏勒河流域植被净初级生产力时空变化及其与气候因子的关系

通过改进的光能利用率CASA模型估算2001-2010年间疏勒河流域陆地生态系统的净第一性生产力（NPP），采用线性趋势分析、变异系数和Hurst指数等方法，分析了NPP的时空变化特征及其与气候因子的相关性。结果表明：①疏勒河流域NPP的空间分布具有明显差异，空间上呈现西北低、东南高的趋势，且具有较明显的经向"条带"分布特征，2001-2010年，NPP平均值为102.26 gC m^-2 a^-1。②2001-2010年，疏勒河流域NPP总体呈增长趋势，年际波动较大，NPP明显增加的区域占总面积25.15%，明显减小的区域约占11.93%。③Hurst指数分析显示，疏勒河流域NPP变化的同向特征强于反向特征，其中持续改善地区占总面积的78.3%，21.7%的区域将由改善转为退化。④在年尺度上，降水是植被NPP变化的主要影响因素，NPP与降水呈弱的正相关关系，与温度相关性不显著；在月尺度上，温度是NPP变化的主要控制因子。疏勒河流域NPP对气候因子不存在明显的时滞和累积效应。     

不同光质光对葡萄愈伤组织增殖和白藜芦醇含量的影响

研究不同光质影响‘黑比诺’种子诱导并继代10个月的葡萄愈伤组织增殖及白藜芦醇含量的结果表明：不同光质下愈伤组织的增殖顺序依次为黄光〉绿光〉红光〉蓝光〉白光；白藜芦醇的含量依次为白光〉黄光〉红光〉蓝光〉绿光：白藜芦醇的生产量是白光〉黄光〉红光〉蓝光〉绿光。     

亚抑菌浓度头孢西丁对耐药质粒接合转移的影响

目的探讨亚抑菌浓度头孢西丁对耐药质粒接合转移的影响,研究病原菌耐药性播散的产生机制。方法采用聚合酶链反应（PCR）分析临床分离的63株产ESBLs肺炎克雷伯菌株SHV型β-内酰胺酶编码基因。质粒接合转移试验采用肉汤接合法。研究不同亚抑菌浓度头孢西丁（0、1、0.5、0.25、0.125μg/ml）和不同作用时间（2、4、6、8、10、12 h）下临床产ESBLs肺炎克雷伯菌株供体菌与受体菌E.coliC600接合转移频率的变化。结果63株临床分离的产ESBLs肺炎克雷伯菌株有41株扩增出SHV型基因,阳性率为65.08%。随着亚抑菌浓度头孢西丁作用时间的增加,接合转移频率有随之增加的趋势。在相同作用时间下,头孢西丁浓度0.125μg/ml作用下的接合转移频率高于其他亚抑菌浓度的作用。结论应合理使用抗菌药物,减少抗菌药物的选择性压力,防止耐药细菌传播。     

池蝶蚌(贝)血细胞显微观察

本文对池蝶蚌血细胞的形态结构及其动态变化进行了研究。根据血细胞形态、大小和密度等特征，把血细胞分为六类：颗粒细胞、透明细胞、浆液细胞、类淋巴细胞、梭形细胞和血栓细胞；并对各种血细胞显微结构予以描述，统计了血细胞胞体大小、细胞核大小、核质比、密度及所占比例，其中颗粒细胞所占比例最大，透明细胞次之，类淋巴细胞最少，颗粒细胞和透明细胞是两种主要的细胞类型，约占总数的82%，担负着最基本的代谢和免疫功能；通过对池蝶蚌血细胞形态的连续观察，发现血细胞存在形态变化现象，推测细胞间可能存在相互转化的情况。