Automatic laser shutdown implications for all optical data networks

Generalized multiprotocol label switching (GMPLS), optical packet, and burst-switched networks in which the synchronous digital hierarchy/synchronous optical network (SDH/SONET) layer is removed may be rendered nonfunctional because the current standard for triggering Automatic Power Reduction (APR) cannot distinguish between a fiber that has been de-energized and a fiber failure. If this standard is applied, without modification, the likelihood of unnecessary amplifier shutdown in optical networks is significant. These shutdown events may impact large regions of the network and render optical links inoperable. To avoid unnecessary amplifier shutdown, amendments to the current operation of APR are suggested.     

Homocysteine and cognitive impairment; a case series in a General Practice setting

Background  

An elevated blood level of homocysteine is a risk factor for cognitive impairment and dementia. Homocysteine can be lowered by folate and/or vitamin B₁₂ supplementation; antioxidants might also be required for optimal reduction in neurovascular tissue. This report presents clinical and radiological findings from administering the antioxidant N-acetylcysteine together with B vitamins to cognitively impaired patients with hyperhomocysteinaemia.     

Quantitation of Ink Transferred During Pharmaceutical Printing Operations Using Inductively Coupled Plasma Atomic Emission Spectroscopy

The identification of solid dosage forms is often achieved through printing with a non-toxic ink. Due to product purity requirements, a method to quantify the amount of ink applied to tablets and capsules is of interest to the pharmaceutical industry.

The following presentation investigated the use of inductively coupled plasma atomic emission spectroscopy (ICP-AES) as a direct method of quantifying the amount of ink on a tablet. Because the ink used contained an iron oxide pigment of known composition, quantitation of the iron content could be used to measure the amount of ink transferred to the tablet.

The quantitative results obtained using ICP-AES were in agreement with calculated values for the volume of ink in the gravure roll. Tablets exposed to “double printing” were easily detected by the ICP-AES method.     

Biobehavioral approaches to the treatment of essential hypertension.

Despite recent advances in the medical management of hypertension, chronically elevated blood pressure remains a major health problem in the United States, affecting almost 50 million Americans. It is widely recognized that lifestyle factors contribute to the development and maintenance of elevated blood pressure. This article critically reviews current approaches to the nonpharmacological treatment of high blood pressure and highlights outcome studies of exercise, weight loss and dietary modification, and stress management and relaxation therapies. Methodological issues in the assessment and treatment of hypertension are discussed, along with possible mechanisms by which lifestyle modification may reduce elevated blood pressure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

White wool,the growth of the ancient dye industry and an expanding colour vocabulary

The possible stimulus to the dye industry in antiquity provided by the breeding of sheep with a white fleece is linked to the development of a colour vocabulary apparent in ancient texts.     

In situ TEM nanoindentation and dislocation-grain boundary interactions: a tribute to David Brandon

As a tribute to the scientific work of Professor David Brandon, this paper delineates the possibilities of utilizing in situ transmission electron microscopy to unravel dislocation-grain boundary interactions. In particular, we have focused on the deformation characteristics of Al–Mg films. To this end, in situ nanoindentation experiments have been conducted in TEM on ultrafine-grained Al and Al–Mg films with varying Mg contents. The observed propagation of dislocations is markedly different between Al and Al–Mg films, i.e. the presence of solute Mg results in solute drag, evidenced by a jerky-type dislocation motion with a mean jump distance that compares well to earlier theoretical and experimental results. It is proposed that this solute drag accounts for the difference between the load-controlled indentation responses of Al and Al–Mg alloys. In contrast to Al–Mg alloys, several yield excursions are observed during initial indentation of pure Al, which are commonly attributed to the collective motion of dislocations nucleated under the indenter. Displacement-controlled indentation does not result in a qualitative difference between Al and Al–Mg, which can be explained by the specific feedback characteristics providing a more sensitive detection of plastic instabilities and allowing the natural process of load relaxation to occur. The in situ indentation measurements confirm grain boundary motion as an important deformation mechanism in ultrafine-grained Al when it is subjected to a highly inhomogeneous stress field as produced by a Berkovich indenter. It is found that solute Mg effectively pins high-angle grain boundaries during such deformation. The mobility of low-angle boundaries is not affected by the presence of Mg.Special title: Advanced Materials and Characterization: Proceedings of the Brandon Symposium; Guest Editors: Wayne D. Kaplan and Srinivasa Ranganathan     

The influence of copolymerization with methacrylic acid on poly(butyl acrylate) film properties

The effects of methacrylic acid (MAA) on the physical properties of polymer made by emulsion copolymerization of butyl acrylate (BA) and MAA were examined. Emulsion polymerizations were performed with and without MAA and at temperatures of 0.1 and 50 °C, using redox initiation so that the radical flux was essentially independent of temperature. The presence of methacrylic acid had only a small effect on gel fraction and on molecular weight, but a profound effect on the film properties; changing the synthesis temperature was found to slightly alter the properties of the copolymer films. Latexes containing MAA formed much stronger films (from creep tests), and significantly increased tack and peel adhesion. This was attributed to intermolecular dipole-dipole interactions of the acid groups. Conductometric titration measurements revealed that the acid groups were predominantly located inside the latex particles, with only a small proportion in the aqueous phase and on the particle surface. Temperature was found not to affect significantly the partitioning of the acid groups in the latex.     

Molecular simulation of the glass transition and proton conductivity of 2,2′‐benzidinedisulfonic acid and 4,4′‐diaminodiphenylether‐2,2′‐disulfonic acid‐based copolyimides as polyelectrolytes for fuel cell applications

The glass transition temperatures (T_gs) and proton conductivities of polyimides synthesized from naphthalene‐1,4,5,8‐tetracarboxylic dianhydride (NTDA), 2,2′‐benzidinedisulfonic acid (BDSA), 4,4′‐diaminodiphenylether‐2,2′‐disulfonic acid (ODADS), and non‐sulfonated diamine monomers have been predicted using molecular dynamics simulations. The specific volumes for two dry and four hydrated NTDA‐based polyimides were plotted versus temperatures above and below T_gs to obtain the glass transition temperatures. The simulation results suggest that the ODADS‐based polyimide membranes exhibit lower T_gs and thus better mechanical properties than the BDSA‐based polyimides, which may be attributed to the high mobility of backbones of ODADS as supported by the vectorial autocorrelation function (VACF) results of this study. In addition, comparison of the simulated T_gs for the dry and hydrated ODADS‐based polyimides has shown that water content in polyimides can affect their T_gs. The proton conductivities of a representative polyimide in both dry and hydrated conditions have been obtained from molecular dynamics simulations of the proton and hydronium ion diffusion. The simulated conductivity for the hydrated NTDA‐ODADS/BAPB cell is in reasonable agreement with the experimental value obtained from the AC impedance method. The relationship between the chemical composition, chain flexibility, and the glass transition and proton conduction of these NTDA‐based polyimides was explored on the basis of VACF and pair correlation function analysis. Copyright © 2006 Society of Chemical Industry