Does switching to low tar/nicotine/carbon-monoxide-yield cigarettes decrease alveolar carbon monoxide measures? A randomized controlled trial.

Assessed the effects of changing to low tar/nicotine/carbon-monoxide-(CO)-yield cigarettes on alveolar carbon monoxide over a 5–6 wk period for 40 adult chronic smokers of high tar/nicotine/CO cigarettes. Ss were assigned to either a 5-wk step-wise brand-reduction treatment or to a delayed-treatment control group. Ss were assessed for (a) resting CO body burden and CO uptake per cigarette and (b) smoking topography and rate. Although CO uptake was significantly lower after Ss smoked low tar/nicotine/CO cigarettes than after smoking their original brand, resting CO body burden did not change. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Einfluß der chemischen Zusammensetzung auf die Relaxationsbehinderung schweißsimulierter warmfester Feinkornbaustähle beim Spannungsarmglühen

Einfluß der Spurenelemente, Bedeutung der Stickstoff-Abbindungsverhältnisse, Aluminiumnitrid, Bornitrid, Absenkung des Kohlenstoffgehaltes, Auswirkung erhöhter Gehalte an Mischkristallbildnern, Warmzugversuche, Zugversuche unter konstanter Kraft.     

Synthesis,Inhibition Potency,Binding Mode,and Antiprotozoal Activities of Fluorescent Inhibitors of Trypanothione Reductase Based on Mepacrine‐Conjugated Diaryl Sulfide Scaffolds

Trypanothione reductase (TR) is a flavoenzyme unique to trypanosomatid parasites and a target for lead discovery programs. Various inhibitor scaffolds have emerged in the past, exhibiting moderate affinity for the parasite enzyme. Herein we show that the combination of two structural motifs of known TR inhibitors — diaryl sulfides and mepacrine — enables the simultaneous addressing of two hydrophobic patches in the active site. The binding efficacy of these conjugates is enhanced over that of the respective parent inhibitors. They show K_ic values for the parasite enzyme down to 0.9±0.1 μm and exhibit high selectivity for TR over human glutathione reductase (GR). Despite their considerable molecular mass and in some cases permanent positive charges, in vitro studies revealed IC₅₀ values in the low micromolar to sub‐micromolar range against Trypanosoma brucei rhodesiense and Trypanosoma cruzi, as well as the malaria parasite Plasmodium falciparum, which lack trypanothione metabolism. The inhibitors exhibit strong fluorescence due to their aminoacridine moiety. This feature allows visualization of the drugs in the parasite where high accumulation was observed by fluorescence microscopy even after short exposure times.     

Organic carbon-water concentration quotients (II(SOC)S and pi(poc)S): measuring apparent chemical disequilibria and exploring the impact of black carbon in Lake Michigan

Chemical concentration quotients measured between water and total organic carbon (TOC) in sediment (II(SOC)) or suspended particulates (pi(poc)) in southern Lake Michigan reveal up to 2 orders of magnitude differences for polychlorinated biphenyl (PCB), dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and polycyclic aromatic hydrocarbon (PAH) compounds with similar octanol-water partition coefficients (K(ow)S). Apparent disequilibria for PAHs, PCDDs, and PCDFs, determined as measured II(SOC)S or pi(poc)S divided by their organic carbon equilibrium partitioning values, are significantly greater than disequilibria of PCBs with similar K(ow)S. Apparent disequilibria, when adjusted for black carbon content by using published black carbon nonlinear partition coefficients (K(f,bc)S) and a Freundlich exponent (n(f)) value = 0.7, still exceed equilibrium predictions for the PAHs, PCBs, and PCDDs but with the PCDF disequilibria uniquely below equilibrium. While Monte Carlo analysis of all the variables associated with the black carbon adjusted disequilibria provides wide confidence intervals for individual chemicals, the large class disequilibria differences between PAHs and PCDFs with respect to the PCBs and PCDDs are highly significant. Use of the PCDD K(f,bc)S for calculating both the PCDF and PCDD disequilibria eliminates their extreme divergence. On the basis of the complexity of carbonaceous geosorbent effects and the apparent variable degrees of chemical sequestration in particles, the disequilibria can be adjusted by chemical class to meet expected near equilibrium conditions between suspended particles and water in the hypolimnion. Although these adjustments to the disequilibria calculations produce consistent and plausible values, the complexities of variable carbonaceous geosorbent affinities for these chemicals in Lake Michigan presently favor use of measured, rather than a priori modeled, steady-state total organic carbon-water concentration quotients indexed to TOC as biogenic organic carbon.     

Thermoset IM-LSI-based C/C-SiC: Influence of flow direction and weld lines on microstructure and mechanical properties

The production of ceramic matrix composites (CMC) based on C/C-SiC is still very cost-intensive and therefore only economical for a few applications. The fabrication of the preforms involves many costs that need to be reduced. In this work, the shaping of the CFRP-preforms is realized by thermoset injection molding, which enables large-scale production. The polymeric matrix used is a multi-component matrix consisting of novolak resin, curing agent and lubricant. Six millimeter chopped carbon fiber with a proportion of 50 wt.% were used as a reinforcement. These ingredients are processed by an industrial equipment for compounding and injection molding in order to manufacture a CFRP demonstrator representing a brake disc. Test specimens are cut out of the demonstrator in different directions in order to investigate influences of flow direction and weld lines on microstructural and mechanical properties. Afterward, the CFRP samples were converted to C/C-SiC composites by the liquid silicon infiltration process. The article addresses the flow behavior of the compound during the injection molding and the building of the weld lines in the demonstrator. In addition, results of the directional dependence of the microstructural and mechanical properties within the fabricated disc in the different production steps are presented.     

Optimization of Broadband Smooth-Wall Circular Horn Antennas

This paper presents the optimization and characterization of broadband circular horn antennas with smooth walls. These antennas are simpler and easier to manufacture than corrugated horns. They work by converting the incoming fundamental mode to a mode mixture, whose total field corresponds to a Gaussian beam pattern at the aperture. The geometry of the horn is found by an optimization algorithm. While smooth-wall horn antennas have been designed for many years, they are inherently band limited because they rely on a correct multimode interference in the aperture to match the total field to a Gaussian distribution. The presented method achieves significantly larger bandwidths by allowing the Gaussian beam parameters, and thus the required mode spectrum in the aperture, to vary with the frequency. Together with an appropriate mirror optics, a receiver system with a bandwidth of more than 3 octaves could be realized.     

Updated Taxonomy for the Network and Service Management Research Field

Network and service management is an established research field within the general area of computer networks. A few years ago, an initial taxonomy, organizing a comprehensive list of terms and topics, was established through interviews with experts from both industry and academia. This taxonomy has since been used to better partition standardization efforts, identify classes of managed objects and improve the assignment of reviewers to papers submitted in the field. Because the field of network and service management is rapidly evolving, a biyearly update of the taxonomy was proposed. In this paper, a large-scale questionnaire is presented which was answered by experts in the field, evaluating the relevance of each individual topic for the next five years. Missing topics, which are likely to become relevant over the next few years, are identified as well. Furthermore, an analysis is performed of the records of papers submitted to major conferences in the area. Based on the obtained results, an updated version of the taxonomy is proposed.     

Nonuniformly Weighted Schwarz Smoothers for Spectral Element Multigrid

A hybrid Schwarz/multigrid method for spectral element solvers to the Poisson equation in \(\mathbb {R}^2\) is presented. It extends the additive Schwarz method studied by Lottes and Fischer (J Sci Comput 24:45–78, 2005) by introducing nonuniform weight distributions based on the smoothed sign function. Using a V-cycle with only one pre-smoothing, the new method attains logarithmic convergence rates in the range from 1.2 to 1.9, which corresponds to residual reductions of almost two orders of magnitude. Compared to the original method, it reduces the iteration count by a factor of 1.5–3, leading to runtime savings of about 50%. In numerical experiments the method proved robust with respect to the mesh size and polynomial orders up to 32. Used as a preconditioner for the (inexact) CG method it is also suited for anisotropic meshes and easily extended to diffusion problems with variable coefficients.     

Thermoelektrische analyse (TEA), eine neue Methode zum gleichzeitigen Studium elektrischer und thermischer Eigenschaften von Polymeren

A new method for the simultaneous study of electrical and thermal properties of polymers is proposed. The thermal electrical analysis (TEA) combines the existing techniques of DSC (or DTA) with the electrical method of thermally stimulated discharge (TSD). TEA measurements were carried out with copolymers of methyl methacrylate (PMMA). The molecular origin of the TSD-current at the lower temperature side of the α₁-relaxation process (glass transition T_g of the PMMA) is related to the disorientation of small polar segments of the comonomer (α₂-relaxation) in the main chain of the PMMA. It can be shown that the TSD-current of the α₂-relaxation (T > 80°C) increases with increasing comonomer content. This supports the molecular interpretation of the α₂-process which is not reflected in the DSC. At higher temperatures frozen in dipoles regain their mobility and show a TSD peak at that temperature which corresponds to the T_g of the PMMA. The TSD ρ-peak at T>T_g can be attributed to trapped space charges which regain their freedom of motion. The results demonstrate the high resolution and resolving power of the TEA-method. TEA is recommended as an analyzing tool to investigate the relationship between the depolarization of dipoles, carrier transport, trapping of real charges and thermal transitions of polymers.