An empirical model predicting the viscosity of highly concentrated, bimodal dispersions with colloidal interactions

The relationship between particle size distribution and viscosity of concentrated dispersions is of great industrial importance, since it is the key to get high solids dispersions or suspensions. The problem is treated here experimentally as well as theoretically for the special case of strongly interacting colloidal particles. An empirical model based on a generalized Quemada equation is used to describe η as a function of volume fraction for mono- as well as multimodal dispersions. The pre-factor η˜ accounts for the shear rate dependence of η and does not affect the shape of the η vs φ curves. It is shown here for the first time that colloidal interactions do not show up in the maximum packing parameter and φ_max can be calculated from the particle size distribution without further knowledge of the interactions among the suspended particles. On the other hand, the exponent ɛ is controlled by the interactions among the particles. Starting from a limiting value of 2 for non-interacting either colloidal or non-colloidal particles, ɛ generally increases strongly with decreasing particle size. For a given particle system it then can be expressed as a function of the number average particle diameter. As a consequence, the viscosity of bimodal dispersions varies not only with the size ratio of large to small particles, but also depends on the absolute particle size going through a minimum as the size ratio increases. Furthermore, the well-known viscosity minimum for bimodal dispersions with volumetric mixing ratios of around 30/70 of small to large particles is shown to vanish if colloidal interactions contribute significantly. Received: 7 June 2000/Accepted: 12 February 2001     

A peptide-derived strategy for specifically targeting the mitochondria and ER of cancer cells: a new approach in fighting cancer

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance. Here, we present a new approach in cancer therapy that specifically targets the mitochondria and ER of cancer cells. We developed a peptide derived from the flexible and transmembrane domains of the human protein NAF-1/CISD2. This peptide (NAF-1^44-67) specifically permeates through the plasma membranes of human epithelial breast cancer cells, abolishes their mitochondria and ER, and triggers cell death with characteristics of apoptosis, ferroptosis and necroptosis. In vivo analysis revealed that the peptide significantly decreases tumor growth in mice carrying xenograft human tumors. Computational simulations of cancer vs. normal cell membranes reveal that the specificity of the peptide to cancer cells is due to its selective recognition of their membrane composition. NAF-1^44-67 represents a promising anti-cancer lead compound that acts via a unique mechanism.

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance.     

Editorial: Mobile Networks in the Era of Big Data

Mobile Networks and Applications -     

Development of a 9-borabicyclo[3.3.1]nonane-mediated solid-phase Suzuki coupling for the preparation of dihydrostilbene analogs

A novel 9-borabicyclo[3.3.1]nonane-mediated solid-phase Suzuki coupling was developed to generate dihydrostilbenes (bibenzyls) and related compounds. Using optimized conditions (20 mol% PdCl₂(dppf), 10 equiv. Et₃N, and 10 equiv. olefin/9-BBN, in 9:1 DMF/H₂O, 50°C, 18 h), high conversions to desired products were generally obtained. A small combinatorial library of derivatives was successfully prepared via radiofrequency tagging and directed sorting techniques.     

利用对称位移脉冲改善分辨率-IMPRESS HMBC

众所周知异核二维实验在中、小分子的结构确定中非常重要. 例如¹H与¹³C/¹⁵N异核远程相关无疑是连接分子中孤立结构碎片及季碳的最有利的工具. 然而，在间接检测的异核二维实验中，间接检测域-异核维的太低分辨率一直是困扰着化学家的主要问题. 过去在有限的采样时间内提高分辨率的方法主要有线性预测、带选择脉冲和控制好的折叠3种方法. 文中介绍一种最新开发出的利用Hadamard激发雕刻的方法. 借助Varian核磁共振系统的高品质射频系统和灵活的软件工具, 用户可以方便的实施新的激发雕 刻方案，极大地改善gHMBC实验的F₁分辨率.     

通讯测量无国界 软件定义测试平台后势看涨

受到产品上市的竞赛所驱使,研究和设计的脚步超越了测试.制造厂商早在ZigBee和802.11n的标准完备之前即推出相关设备,传统仪器制造商则完全没有推出预制的标准测试系统.这个现象主要是因为传统的周期是推出无线标准、主要使用者制造原型设备,再针对大量商业用途开发测试设备;而这个循环周期过于漫长.当这种模式同时出现在数十种新发表的标准上,测试设备制造厂商面对一个艰难的决定:若不是比符合标准的测试设备晚一点上市,就是可能要花数百万元的研发经费在一项不被采用的标准上,这种现象促使工程师寻找具有弹性且立即可用的解决方案.     

Facile preparation of bis(thiocarbonyl)disulfides via elimination

A robust facile synthetic preparation of bis(thiocarbonyl)disulfides is presented. The route follows an elimination mechanism rather than the more common oxidation. Addition of p-tosyl chloride to a thiocarbonyl thiolate results in the elimination of the chloride by the trithiocarbonate anion and subsequent elimination of the tosyl leaving group (by a second thiocarbonyl thiolate). The side products of the reaction are bis(4-methylphenyl)disulfone and tosylate salts/acids.     

On the number of rectangulations of a planar point set

We investigate the number of different ways in which a rectangle containing a set of n noncorectilinear points can be partitioned into smaller rectangles by n (nonintersecting) segments, such that every point lies on a segment. We show that when the relative order of the points forms a separable permutation, the number of rectangulations is exactly the (n+1)st Baxter number. We also show that no matter what the order of the points is, the number of guillotine rectangulations is always the nth Schröder number, and the total number of rectangulations is O(n²⁰/n⁴).