A basket tetradecavanadate cluster with blue luminescence

A blue luminescent tetradecavanadate compound, [Et4N]5[V14O36Cl], has been synthesized. It possesses an unprecedented half-open basket framework. Through the {ABAB}-type stacking, the {V14O36} clusters form infinite one-dimensional channels with considerable accessible volume in the crystalline state.     

Chains, ladders and sheets of d metal–organic polymers generated from the flexible bipyridyl ligands

By use of the three-layer diffusion method, reactions of flexible bipyridyl ligands (4,4′-bpp or 3,3′-bpp) with M(II) salts (M = Zn, Cd) and multi-carboxylate ligands resulted in the formation of four interesting d¹⁰ metal–organic coordination polymers: [Zn(μ-4,4′-bpp)Br₂]_n (1), [Zn(μ-4,4′-bpp)(1,2-bdc)]_n · nH₂O (2), [Zn(μ-3,3′-bpp)(1,3-bdc)]_n · nCH₃OH · 2nH₂O (3) and [Cd(μ-3,3′-bpp)(C₄H₂O₄)]_n · 3nH₂O (4) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 3,3′-bpp = 2,2 ′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene; bdc=benzenedicarboxylate, C₄H₄O₄ = fumaric acid). Complex 1 has a 2D sheet structure consisting of two unusual zigzag Zn(II) chains which are nearly perpendicular to each other. Complex 2 is comprised of two-leg ladders, in which [Zn(4,4′-bpp)] chains serve as the side rails and 1,2-bdc ligands serve as the cross rungs. In complex 3, every two 1,3-bdc ligands connect the neighbouring Zn(II)-3,3′-bpp dimetallic rings in η¹ coordination modes into an interesting chain structure. Complex 4 consists of an anionic macrocycle-containing cadmium dicarboxylate sheets that are separated by 3,3′-bpp. These d¹⁰ metal complexes exhibit high thermal stabilities and strong luminescence efficiencies.     

基于复杂性研究的Internet安全模型

回顾了基于复杂性科学和复杂网络研究的相关理论建立的几种Internet安全大范围模式行为的模型．从Internet复杂系统的Power-Law分布规律出发，论述了该分布规律对网络安全建模的影响，然后围绕网络安全的两个方面，即病毒传播和网络鲁棒性，分别论述了基于复杂系统和复杂网络研究成果建立的病毒传播的定量模型，以及网络鲁棒性与复杂网络结构的定性关系模型，最后还展望了未来该领域的研究前景．     

SEM analysis of the changes of carbon layer structure of mesocarbon microbeads heat-treated at different temperatures

Mesocarbon microbeads (MCMB) with narrow size distribution, excellent sphericity and no obvious conglutination have been prepared with a coal tar pitch containing quinoline insolubles (QI) as the raw material. Optical microscopy and scanning electron microscopy (SEM) are used to examine the structure of the MCMB. It has been found that SEM technique shows the structural information of MCMB clearly in the form of micrographs even when the structure of MCMB is complex, while the optical technique is useful for analysis of the regular structure of the mesophase spheres but cannot be effectively used to analyze either the complex structure of the green MCMB or the structures of the further heat-treated ones at different temperatures. According to the characteristics of the carbon layers, the structures of the as-prepared MCMB in the present experiment could be classified as (I) Parallel Layer type structure and (2) Bent Layer type structure with the carbon layers gathering at one or two points in the MCMB. In the experiments, SEM is also utilized to investigate the structures of MCMB that are heat-treated at different temperatures. It has been found that the MCMB without any further heat-treatment show no layered-carbons, while the ones heat-treated at temperaturehigher than 1000℃ exhibit obvious layered carbons across their sections. When increasing the heat-treatment temperature, the carbon layers become thinner and flatter.     

关于如何理解物理量熵的若干思考

热力学作为物理学最难理解的一门分支学科,其改革与创新至关重要。通过热力学与电学之间的类比,引入了基于直觉认知的热荷和热荷量的概念,由此得出熵就是热荷量这一简单而明确的定义。其结果是,熵(热荷量)与热量这两个不同性质的物理量得以清晰地区分开来,从而不仅消除了热力学的抽象性,而且还消除了熵这个物理量之前在概念上的模糊性。以全新的面貌出现的热力学不但有利于我国广大科研和工程技术人员的理解、掌握、应用和创新,有利于提升我国的科技软实力,而且也有利于大、中学生的物理教学和热力学知识的普及。     

高效液相色谱柱后衍生测定鸡组织中甲基盐霉素残留量

建立了鸡组织中甲基盐霉素的高效液相色谱柱后衍生化分析方法.样品经异辛烷提取,离心后上层有机相过硅胶固相萃取小柱,洗脱液浓缩后用V(甲醇)∶ V(水)=90∶ 10混合液溶解.采用Inertsil ODS-3 C18柱,以V(甲醇): V(乙酸)∶ V(水)=94∶ 3∶ 3为流动相,香草醛为衍生剂进行高效液相色谱柱后衍生分析,520 nm检测,外标法定量.方法检出限为6 μg/kg; 定量限为20 μg/kg; 添加浓度在20～1800 μg/kg范围内,平均添加回收率为76.4%～93.1%; 批内相对标准偏差(RSD)在2.6%～8.9%之间; 批间相对标准偏差(RSD)在4.7%～9.7%之间.样品浓度在0.07～10.0 mg/L范围内与峰面积呈良好的线性关系,r>0.9993.     

啤酒酵母中β-(1-3)葡聚糖的提取及其性能分析

本文采用Sevage脱蛋白法、酸溶液浸提法、碱溶液浸提法对啤酒废酵母细胞壁中的β-(1-3)葡聚糖作了提取试验,并对所获多糖进行生化特性分析,阐述了碱溶液浸提法是从啤酒酵母中回收高质量β-(1-3)葡聚糖的理想途径．     

Some Measurement-Based Characterizations of Separability of Bipartite States

Importance of quantum entanglement has been demonstrated in various applications. Usually, separability of a bipartite state is defined by its algebraic structure, i.e. a convex combination of product states. But it seems to be hard to check separability (equivalently, entanglement) of a state from its algebraic structure. In this note, we give some characterizations of separability of bipartite states based on POVM measurements. For bipartite pure states, we prove the separability, Bell locality, unsteerability and classical correlation are the same. As a consequence, every entangled pure bipartite state is always Bell nonlocal, steerable and quantum correlated.

     

氮添加对亚热带常绿阔叶林土壤有机碳及土壤呼吸的影响

以福建省武夷山亚热带常绿阔叶米槠林为研究对象, 开展氮添加实验。采用4个氮添加梯度(CK, N50, N100和N150, 分别表示氮添加0, 50, 100和150 kg/(hm²·a))模拟自然氮沉降变化, 探究氮添加对土壤有机碳及土壤呼吸的影响。结果表明, 氮添加对表层土壤(0~20 cm)总有机碳的影响不显著, 对颗粒态有机碳(POC)和矿物结合态有机碳(MAOC)两种不同碳组分含量的影响不同。其中, N100和N150处理分别使土壤POC含量显著上升110.7%和147.9% (p₁ = 0.024, p₂ < 0.001); 土壤MAOC含量则随氮添加量升高呈下降趋势, 但差异不显著。土壤呼吸速率的年际波动呈单峰式, 且在不同观测时间内, 各样地土壤呼吸速率对氮添加的响应不同。通过土壤呼吸速率与土壤温度的拟合方程计算, 得到2018—2020年CK, N50, N100和N150样地土壤呼吸年均碳排放量分别为1205.31, 1191.56, 1287.56和1128.61 g C/m²。其中, N50样地与CK样地无显著差异, N100样地显著上升6.82% (p<0.001), N150显著下降 6.8% (p<0.001), 即N100可以促进土壤呼吸年碳排放, 而N150对土壤呼吸年碳排放有抑制作用。     

通过热力学与电学的类比加深对于熵的理解

恰当地开展分支学科之间的类比是理解物理学的一条有效途径。在借鉴电荷概念引入热荷概念之后,继而直接将熵定义为热荷量,使之成为一个通俗易懂的物理量。以此为基础,在电流与熵流的连续性、驱动力,以及它们与能流之间的关系和电流与熵流在流动过程中的熵产生等方面对热力学与电学进行了较为全面的类比。这样不仅能凸显出热力学与电学的一些基本物理过程之间的相似性或共性,以及客观世界的内在和谐性,而且能更加鲜明地反衬出它们之间的差异即各自的个性,从而加深对于熵的理解。