Structural characterization,thermal stability,and solvent de-/ad-sorption behavior of two d10 M(II) (M = Cd and Zn) coordination polymers constructed by 1,3,5-tris(4-pyridylsulfanyl-methyl)-2,4,6-trimethyl-benzene (L1)

Two d¹⁰ M(II) (M = Cd and Zn) coordination polymers (CPs) with chemical formulas, {[Cd(L¹)(NCS)₂(H₂O)]⋅C₂H₅OH}_n (1) , and {[Zn(L¹)(NCS)₂]⋅C₂H₅OH⋅0.5H₂O}_n (2) (L¹ = 1,3,5-tris(4-pyridylsulfanylmethyl)-2,4,6-trimethylbenzene) were synthesized and structurally characterized by single-crystal x-ray diffraction method. In compound 1 , the coordination environment of Cd(II) ion is distorted octahedral bonded to three nitrogen donors from three L¹ ligands located in a facial-position, two nitrogen donors from NCS⁻ and one water molecule. The L¹ acts as a bridge ligand with tris-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Cd(II) to form a two-dimensional (2D) zigzag-like layered metal-organic frameworks. Adjacent 2D layers are then arranged orderly in an ABAB manner to complete its three-dimensional (3D) supramolecular architecture. In compound 2 , the coordination environment of Zn(II) ion is distorted tetrahedral bonded to two nitrogen donors from two L¹ ligands and two nitrogen donors from two NCS⁻ ligands. The L¹ acts as a bridge ligand with bis-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Zn(II) ions to form a one-dimensional (1D) zigzag-like polymeric chain. Adjacent chains are arranged orderly in an alternate ABAB manner to generate a 2D framework and then further arranged in an AAA manner to complete its 3D supramolecular architecture. The structural characterization as well as thermal-stability and solvents de-/ad-sorption behavior of 1 and 2 are studied and discussed in details.     

Supramolecular architectures and crystal structures of gold(III) compounds with semicarbazones

The synthesis and crystal structures of two novel semicarbazones and four gold(III) compound derivatives of these semicarbazones are presented. A pattern in the formation of the semicarbazones shows the association of Cl^– ions held together by intra- and intermolecular forces. [AuCl₄]^? and [AuBr₄]^? anions are co-crystallised with these semicarbazone ligands, and the packing architectures revealed by a single-crystal X-ray diffraction analysis showed the different influences of the anions and the association of these chemical species by intermolecular forces on the crystal packing. Crystal engineering led to gold(III) compounds that are stabilised by relevant hydrogen bonding networks, which demonstrated their importance to the supramolecular organisation of the studied compounds. Interestingly, Cl???Br interactions are observed and contribute to the formation of the supramolecular structures. Elemental analysis data and spectroscopic properties in the solid state and solution are also described.     

基于快速神经网络架构搜索的鲁棒图像水印网络算法

为解决深度学习在图像水印算法中计算量大且模型冗余的问题，提高图像水印算法在抵抗噪声、旋转和剪裁等攻击时的鲁棒性，提出基于快速神经网络架构搜索（neural architecture search，NAS）的鲁棒图像水印网络算法。通过多项式分布学习快速神经网络架构搜索算法，在预设的搜索空间中搜索最优网络结构，进行图像水印的高效嵌入与鲁棒提取。首先，将子网络中线性连接的全卷积层设置为独立的神经单元结构，并参数化表示结构单元内节点的连接，预先设定结构单元内每个神经元操作的搜索空间；其次，在完成一个批次的数据集训练后，依据神经元操作中的被采样次数和平均损失函数值动态更新概率；最后，重新训练搜索完成的网络。水印网络模型的参数量较原始网络模型缩减了92%以上，大大缩短了模型训练时间。由于搜索得到的网络结构更为紧凑，本文算法具有较高的时间性能和较好的实验效果，在隐藏图像时，对空域信息的依赖比原始网络更少。对改进前后的2个网络进行了大量鲁棒性实验，对比发现，本文算法在CIFAR-10数据集上对抵抗椒盐噪声和旋转、移除像素行（列）等攻击优势显著；在ImageNet数据集上对抵抗椒盐高斯噪声、旋转、中值滤波、高斯滤波、JPEG压缩、裁剪等攻击优势显著，特别是对随机移除行（列）和椒盐噪声有较强的鲁棒性。     

Effect of chain architecture on the phase transition of star and cyclic poly(N‐isopropylacrylamide) in water

The heat‐induced phase transition of aqueous solutions of Poly(N‐isopropylacrylamide) (PNIPAM) in water is examined for a four‐arm PNIPAM star (s‐PNIPAM), a cyclic PNIPAM (c‐PNIPAM), and their linear counterparts (l‐PNIPAM) in the case of polymers (1.0 g L^?1) of 12,700 g mol^?1 < M_n < 14,700 g mol^?1. Investigations by turbidity, high‐sensitivity differential scanning calorimetry (HS‐DSC), and light scattering (LS) indicate that the polymer architecture has a strong effect on the cloud point (T_c: decrease for s‐PNIPAM; increase for c‐PNIPAM), the phase transition enthalpy change (ΔH decrease for s‐PNIPAM and c‐PNIPAM), and the hydrodynamic radius of the aggregates formed above T_c (R_H: c‐PNIPAM < s‐PNIPAM < l‐PNIPAM). The properties of s‐PNIPAM are compared with those of previously reported PNIPAM star polymers (3 to 52 arms). The overall observations are described in terms of the arm molecular weight and the local chain density in the vicinity of the core of the star, by analogy with the model developed for PNIPAM brushes on nanoparticles or planar surfaces. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2059–2068.     

步进扫描差示扫描量热法研究不同链结构的聚乙烯类聚烯烃热力学特性

采用步进扫描差示扫描量热法研究了几种具有不同链结构的聚乙烯类聚烯烃的热力学性质.结果表明，不同链结构的聚烯烃在热力学平衡熔融态下，其绝对比热容的温度依赖性在实验误差范围内几乎相同；而无论链结构的变化如何，在极低温度下稳定结晶态的热容也非常接近.但在熔融温度范围内，比热容对不同聚烯烃的链结构非常敏感，这是由于在远低于聚烯烃主熔化峰温度范围内，聚乙烯晶体结构中的不同支链的影响.在时间-热流的步进扫描曲线中，具有长支链结构的聚烯烃表现出独特的熔融-再结晶行为，这可能是由于交联点之间较长的受约束链段的运动在熔融过程中得到释放并重排所致.     

A proposal for a convertible stadium roof structure derived from Watt-I linkage

In this paper, a novel convertible stadium roof structure is introduced, which has been derived from a special geometric configuration of Watt-I linkage, a 1-DoF mechanism used in robot technologies as anthropomorphic fingers. The proposed structure can offer a wide range of different shape configurations according to the environmental conditions and spatial needs, thus offering several aesthetic and functional advantages over existing solutions. This paper serves as a feasibility investigation of this concept, mainly from geometric and structural point of view. To that affect, first kinematic analysis and geometric design of this linkage are introduced. Then, structural analyses of the proposed structure with realistic dimensions and loading conditions are performed in three different geometric configurations, in order to discuss strength and stiffness limitations. Finally, potential cover materials and actuators are briefly discussed.     

基于Socket通信的工业机器人监控系统研究

针对Epson-G6和Staubli-TX90工业机器人，研究一种基于Socket通信的工业机器人监控系统。系统分为本地监控端和Web远程监控端。基于TCP协议和Socket通信技术，编写了机器人控制器服务端程序和MFC类库开发的客户端程序，客户端分为通讯功能模块，末端坐标轨迹存储模块和基于OpenGL类库的运动姿态展现模块。在此基础上, 基于J2EE架构和WebSocket通信协议编写了Web远程监控端程序，分为用户管理模块和实时监控模块。系统实现了机器人末端坐标轨迹的采集并远程存储至PostgreSQL数据库，同时通过逆运动学计算展现了机器人三维运动姿态，并在Web页面以动态曲线方式监控机器人的末端坐标轨迹。     

Controlling Necking in Extrusion Film Casting Using Polymer Nanocomposites

The research described was concerned with the effect of layered-silicate-based organically modified nanoclay fillers on controlling the extent of necking in a polymer melt extrusion film casting (EFC) process. We show that a linear polythylene resin (such as a linear low-density polyethylene—LLDPE) filled with a very low percentage of well-dispersed (or intercalated) nanoclay displays an enhanced resistance to the necking phenomenon. In general, melt-compounded nanoclay-filled LLDPE resin formulations displayed a higher final film width (less necking), thus a lower final film thickness (greater draw down for the same draw ratio), and cooled down faster when compared to the base LLDPE resin. Incorporation of nanoclay filler in the mainly linear chain LLDPE resin led to significant modification of the melt rheological properties that, in turn, affected the melt processability of these formulations. Primarily, the intercalated nanoclay-filled LLDPE formulations displayed the presence of strain-hardening in unaxial extensional rheology. Additionally, the presence of well-dispersed nanoclay in the LLDPE resin led to a display of prominent extrudate swell indicating the presence of melt elasticity in such formulations. The presence of melt elasticity, as shown by shear rheology and strain-hardening, observed by uniaxial extensional rheology, contributed to the LLDPE nanoclay formulations displaying an enhanced resistance to necking for these films. It can be concluded that linear chain polymers susceptible to necking in an EFC process can be made more resistant to such necking by using nanoclay fillers at very low levels of loading.     

Statistical assertion: A more powerful method for debugging scientific applications

Traditional debuggers are of limited value for modern scientific codes that manipulate large complex data structures. Current parallel machines make this even more complicated, because the data structure may be distributed across processors, making it difficult to view/interpret and validate its contents. Therefore, many applications’ developers resort to placing validation code directly in the source program. This paper discusses a novel debug-time assertion, called a “Statistical Assertion”, that allows using extracted statistics instead of raw data to reason about large data structures, therefore help locating coding defects. In this paper, we present the design and implementation of an ‘extendable’ statistical-framework which executes the assertion in parallel by exploiting the underlying parallel system. We illustrate the debugging technique with a molecular dynamics simulation. The performance is evaluated on a 20,000 processor Cray XE6 to show that it is useful for real-time debugging.