Synthesis, Crystal Structure and Properties of a New 3D Supramolecular Metal–Organic Framework with Stable Tunnels

A flexible polycarboxyl ligand of tetrahydrofuran-2,3,4,5-tetracarboxylic acid (H₄THFTCA) and a common rigid aromatic ligand of 1,10-phenanthroline (phen) have been successfully co-assembled with Cu(NO₃)₂·3H₂O to give out a novel 3D supramolecular metal–organic framework (MOF) compound, [Cu₂(THFTCA)(phen)(H₂O)₂·CH₃CH₂OH·3H₂O] _n (1), by a solution self-assembly process. Compound 1 has been characterized as a 2D layered coordination polymer constructed by THFTCA^4? and Cu²⁺ ions, and the layer present a novel (3.5²)(3².5³.6⁴.7) topological network. Interestingly, the layers are fused each other via strong π–π stacking interactions among adjacent ligands of the terminal phen, so that a 3D supramolecular MOF with 1D rhomboidal tunnels array is formed. The thermogravimetric analysis and corresponding powder X-ray diffraction analysis have revealed that the tunnels structure of 1 could be retained after all guest molecules are removed, and the framework could resist the collapse even heating up to 210?°C. An opinion has also been proposed that the larger accessible volume of the guests means the larger stress on the backbone of the MOF after the guests are removed, and the stress is harmful to the stability of the supramolecular porous structure. Finally, the application properties based on the porous structure have also been primarily evaluated.     

正极材料LiFePO4/C掺杂改性的研究进展

LiFePO₄/C具有高温稳定性好、价格低廉、循环性能良好、环保等性能,是一种具有发展潜力的锂离子动力电池正极材料之一,因此在锂离子电池行业备受关注。但由于其电子电导率低以及锂离子扩散速率慢等缺点制约其发展。介绍了磷酸铁锂的结构、性能、充放电原理和掺杂机理,尤其对近年来LiFePO₄/C材料的掺杂改性研究进行了综述。     

分散固相萃取净化离子色谱-串联质谱测定茶叶中高氯酸盐

目的 建立分散固相萃取净化离子色谱-串联质谱法测定茶叶中高氯酸盐的含量。方法 样品经80 ℃超纯水浸泡提取30 min, 定性滤纸过滤, 滤液采用分散固相萃取技术, 以多壁碳纳米管和N-丙基乙二胺键合固相吸附剂吸附提取液中的杂质, 待测样品由离子色谱-串联质谱法测定, 内标法定量。结果 高氯酸盐浓度0.02~10.00 μg/L有良好的线性关系, 相关系数r2为0.9998, 检出限为0.6 μg/kg, 定量限为2.0 μg/kg, 加标回收率为80.1%~99.2%, 相对标准偏差为3.89%~7.68% (n=6)。对市场上随机购买的茶叶样品进行测定, 样品的含量为0.15~0.72 mg/kg。结论 该方法简便、可靠、稳定、灵敏度高, 可用于茶叶中高氯酸盐快速检测。     

ZnO-C三维网络结构涂层的制备及其储锂性能研究

通过简单的刮涂工艺成功地在铜箔表面制备出具有三维网络结构的ZnO-C复合涂层。采用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)和透射电镜(TEM)对复合涂层的晶体结构及微观形貌进行研究。结果表明: 该涂层由宽度为0.1~1 μm的碳基枝条相互连接形成连续的三维网络结构, 碳基枝条内包含ZnO纳米粒子和尺寸约为2 nm的微孔。该涂覆在铜箔表面的复合涂层可直接用作锂离子电池的负极。电化学测试结果表明: ZnO-C复合涂层负极材料在0.1 A/g电流密度下经过100次循环后的比容量为855 mAh/g, 并且在循环过程中未出现容量衰减现象; 在5A/g大电流密度下的比容量为418 mAh/g, 是0.1 A/g电流密度下比容量的51.3%。     

社会网络中基于节点平均度的k-度匿名隐私保护方案

社会网络数据的发布可能导致用户隐私被泄露,例如用户的身份信息可能被恶意攻击者通过分析网络中节点的度数识别出来,针对这个问题提出一种基于节点平均度的k-度匿名隐私保护方案.方案首先利用基于平均度的贪心算法对社会网络节点进行划分,使得同一分组中节点的度都修改成平均度,从而生成k-度匿名序列;然后利用优先保留重要边的图结构修改方法对图进行修改,从而实现图的k-度匿名化.本方案在生成k-度匿名序列时引入平均度,提高了聚类的精度,降低了图结构修改的代价.同时,由于在图结构修改时考虑了衡量边重要性的指标—邻域中心性,重要的边被优先保留,保持了稳定的网络结构.实验结果表明,本方案不仅能有效地提高网络抵抗度攻击的能力,还能极大降低信息损失量,在保护用户隐私的同时提高了发布数据的可用性.     

稀土化合物浆料对CVD金刚石厚膜的刻蚀

ＣＶＤ金刚石厚膜具有极高的硬度,使得对其进行表面抛光极为困难．传统的机械抛光方法既不经济又耗费时间,而一些新的抛光技术又由于实验条件限制而难以推广．针对以上情况,我们寻求到一种新的化学刻蚀方法,即利用稀土化合物浆料对金刚石厚膜生长表面进行刻蚀,破坏表面的晶粒使之成为晶骸,降低表面的耐磨性,以提高表面粗糙的金刚石厚膜的抛光效率．     

Detection of Ricin Intoxication in Mice Using Serum Peptide Profiling by MALDI-TOF/MS

Ricin toxin has been regarded as one of the most potent poisons in the plant kingdom, and there is no effective therapeutic countermeasure or licensed vaccine against it. Consequently, early detection of ricin intoxication is necessary. In this study, we took mice as test subjects, and used the technique of Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) and ClinProt™ microparticle beads to set up an effective detection model with an accuracy of almost 100%. Eighty-two peaks in the mass range 1000–10,000 m/z were detected by ClinProTools software, and five different peaks with m/z of 4982.49, 1333.25, 1537.86, 4285.05 and 2738.88 had the greatest contribution to the accuracy and sensitivity of this model. They may therefore provide biomarkers for ricin intoxication.     

重庆地区地基承载力的确定——《工程地质勘察规范》(DBJ50-043-2005)讲座之四

<正>引言地基承载力的确定是地基勘察评价的关键内容之一。新颁布的重庆市工程建设标准《工程地质勘察规范》(DBJ50-043-2005)(以下简称本标准)在地基承载力确定方     

工程勘察中岩土性质指标的确定——《工程地质勘察规范》(DBJ50-043-2005)讲座之五

<正>引言岩土性质指标的确定是工程地质勘察评价的核心内容之一,新颁布的重庆市工程建设标准《工程地质勘察规范》(DBJ50-043-2005)(以下简称本标准)用专章对此进行了规定,在岩土样最小试验数据量、单指标统计、双指标统计、     

一种HEVC整像素运动估计优化算法

对HEVC整像素运动估计算法进行优化,目的是在保持编码视频压缩后码流率和解码视频图像质量基本不变的同时,降低编码耗时。首先,统计了不同视频序列的进行帧间预测时整像素运动估计的搜索步长的分布。进而根据统计结果,改进了不同搜索步长下的分支搜索模板。同时调整了整像素运动估计的提前终止条件。最终比较了测试视频序列优化前后编码输出的YUV分量、码流和耗时。实验结果表明,对于class E(1 920×1 080)视频序列,在编码后视频质量的客观值(YUV分量)最多下降0.182 2 d B,比特率最多上升0.40%,耗时最少下降1.25%。