Calcium Silicate Hydrates Studied by Small-Angle Neutron Scattering (SANS)

Small-angle neutron scattering (SANS) was used to study calcium silicate hydrate (C-S-H) formed via pozzolanic reaction between calcium oxide and ultrafine silica in water or polymer solutions at a temperature of 20°C. The SANS profile of this product was consistent with a structure that consisted of platelets with maximum diameters of ∼20 nm (± 5 nm) in the x – y plane, which was similar to a structure that had been deduced in previous work via X-ray diffractometry. The presence of two different types of superplasticizer in solution (at a concentration of 10 g/L) had no significant effect on its formation kinetics or its SANS profile.     

Effect of Pulsed Laser Radiation on the Properties of Resistive Thick Films Based on Nickel and Barium Borides

We have used atomic force microscopy to study the surface morphology of resistive thick films based on powders of nickel and barium borides and a glass binder, treated with laser radiation. We used x-ray phase analysis to study the phase composition of these films. We have observed a change in the surface morphology, the phase composition, and the electrical resistance of the studied films as a function of the laser radiation energy.     

A conservative integral for determining stress intensity factors of a bimaterial notch

This work presents regular and singular asymptotic solutions for non-planar quasi-circular cracks. Regular asymptotic solutions, which do not give rise to hyper-singular stresses near the crack tip, are developed in the general three-dimensional setting. Singular asymptotic solutions are considered for axisymmetric problems only, because those problems do not involve hyper-singularity. The validity of asymptotic solutions for planar and non-planar cracks is investigated by comparing them with detailed numerical and analytical solutions. Also asymptotic solutions are applied to analysis of quasi-static crack growth in three dimensions.     

Gold nanorods with a hematoporphyrin-loaded silica shell for dual-modality photodynamic and photothermal treatment of tumors in vivo

Nanocomposites （NCs） consisting of a gold nanorod core and a mesoporous silica shell doped with hematoporphyrin （HP） have been fabricated in order to improve the efficiency of cancer treatment by combining photothermal and photodynamic therapies （PDT ＋ PTT） in vivo. In addition to the long-wavelength plasmon resonance near 810-830 nm, the fabricated NCs exhibited a 400-nm absorbance peak corresponding to bound HP, generated singlet oxygen under 633-nm excitation near the 632.5-nm Q-band, and produced heat under a 808-nm near-infrared （NIR） laser irradiation. These modalities were used for a combined PDT ＋ PTT treatment of large （about 3 cm3） solid tumors in vivo with a xenorafted tumor rat model. NCs were directly injected into tumors and irradiated simultaneously with 633-nm and 808-nm lasers to stimulate the combined photodynamic and photothermal activities of NCs. The efficiency of the combined therapy was evaluated by optical coherence tomography, histological analysis, and by measurements of the tumor volume growth during a 21-day period. The NC-mediated PDT led to weak changes in tissue histology and to a moderate 20% decrease in the tumor volume. In contrast, the combined PDT ＋ PTT treatment resulted in the large-area tumor necrosis and led to dramatic decrease in the tumor volume.     

Au@Hg Nanoalloy Formation Through Direct Amalgamation: Structural,Spectroscopic, and Computational Evidence for Slow Nanoscale Diffusion

Dynamic core–shell nanoparticles have received increasing attention in recent years. This paper presents a detailed study of Au–Hg nanoalloys, whose composing elements show a large difference in cohesive energy. A simple method to prepare Au@Hg particles with precise control over the composition up to 15 atom% mercury is introduced, based on reacting a citrate stabilized gold sol with elemental mercury. Transmission electron microscopy shows an increase of particle size with increasing mercury content and, together with X‐ray powder diffraction, points towards the presence of a core–shell structure with a gold core surrounded by an Au–Hg solid solution layer. The amalgamation process is described by pseudo‐zero‐order reaction kinetics, which indicates slow dissolution of mercury in water as the rate determining step, followed by fast scavenging by nanoparticles in solution. Once adsorbed at the surface, slow diffusion of Hg into the particle lattice occurs, to a depth of ca. 3 nm, independent of Hg concentration. Discrete dipole approximation calculations relate the UV–vis spectra to the microscopic details of the nanoalloy structure. Segregation energies and metal distribution in the nanoalloys were modeled by density functional theory calculations. The results indicate slow metal interdiffusion at the nanoscale, which has important implications for synthetic methods aimed at core–shell particles.     

Age-Related Changes in the Fibroblastic Differon of the Dermis: Role in Skin Aging

Skin aging is a multi-factorial process that affects nearly every aspect of skin biology and function. The processes developing in the skin during aging are based on fundamental molecular mechanisms associated with fibroblasts, the main cellular population of the dermis. It has been revealed that the amount of fibroblasts decreases markedly with age and their functional activity is also reduced. This inevitably leads to a decrease in the regenerative abilities of the skin and the progression of its aging. In this review we consider the mechanisms underlying these processes, mainly the changes observed with age in the stem/progenitor cells that constitute the fibroblastic differon of the dermis and form their microenvironment (niches). These changes lead to the depletion of stem cells, which, in turn, leads to a decrease in the number of differentiated (mature) dermal fibroblasts responsible for the production of the dermal extracellular matrix and its remodeling. We also describe in detail DNA damages, their cellular and systemic consequences, molecular mechanisms of DNA damage response, and also the role of fibroblast senescence in skin aging.     

Structural Wear-Resistant Sintered Materials Based on Titanium

A principle is proposed for increasing the wear resistance of structural titanium materials by addition (together with a moderate number of hard inclusions) of alloying elements which, without decreasing the strength and ductility of titanium, increase the wear resistance of the material thanks to the formation of oxide films during friction that prevent seizing of the contacting surfaces. Requirements for the hard inclusions and alloying additions were defined, the basic of which is a high affinity of the alloying elements for oxygen. Grades of wear-resistant structural titanium materials were created and recommended for use in the production of components operating in friction units at room temperature (IT20, IT15V) and at 250-550°C (IT16M). The mechanical properties and operating conditions (sliding rate, pressure, temperature, counterbody material, atmosphere) of the sintered titanium materials were investigated.     

Don't pull punches.

Comments on C. A. Kiesler's (1977) editorial on the training of psychiatrists and psychologists, charging that the editorial was a tenuous rebuttal to the American Psychiatric Association. The entire psychological community must stand together against this powerful group of psychiatrists, and leaders of the psychologists should present a forceful defense of the survival and legitimacy of psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Styrene–substituted‐styrene copolymerization using diphenylzinc–metallocene–methylaluminoxane systems

Homopolymerization of disubstituted styrenes (2,4‐ and 2,5‐dimethylstyrene) and trisubstituted styrene (2,4,6‐trimethylstyrene) and their copolymerization with styrene were carried out using diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n‐BuCp)₂TiCl₂ and for half‐metallocene CpTiCl₃. The studied comonomers were found to be less reactive than p‐tertbutylstyrene, p‐methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di‐ and tri‐methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry