Release of carbon nanotubes from an epoxy-based nanocomposite during an abrasion process

The abrasion behavior of an epoxy/carbon nanotube (CNT) nanocomposite was investigated. An experimental setup has been established to perform abrasion, particle measurement, and collection all in one. The abraded particles were characterized by particle size distribution and by electron microscopy. The abrasion process was carried out with a Taber Abraser, and the released particles were collected by a tube for further investigation. The particle size distributions were measured with a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS) and revealed four size modes for all measured samples. The mode corresponding to the smallest particle sizes of 300-400 nm was measured with the SMPS and showed a trend of increasing size with increasing nanofiller content. The three measured modes with particle sizes from 0.6 to 2.5 μm, measured with the APS, were similar for all samples. The measured particle concentrations were between 8000 and 20,000 particles/cm(3) for measurements with the SMPS and between 1000 and 3000 particles/cm(3) for measurements with the APS. Imaging by transmission electron microscopy (TEM) revealed that free-standing individual CNTs and agglomerates were emitted during abrasion.     

Occurrence of pharmaceuticals and personal care products in german fish tissue: a national study

German Environment Specimen Bank (GESB) fish tissue samples, collected from 14 different GESB locations, were analyzed for 15 pharmaceuticals, 2 pharmaceutical metabolites, and 12 personal care products. Only 2 pharmaceuticals, diphenhydramine and desmethylsertraline, were measured above MDL. Diphenhydramine (0.04-0.07 ng g(-1) ww) and desmethylsertraline (1.65-3.28 ng g(-1) ww) were measured at 4 and 2 locations, respectively. The maximum concentrations of galaxolide (HHCB) (447 ng g(-1) ww) and tonalide (AHTN) (15 ng g(-1) ww) were measured at the Rehlingen sampling site in the Saar River. A significant decrease in HHCB and AHTN fish tissue concentrations was observed from 1995 to 2008 at select GESB sampling sites (r(2) = 0.69-0.89 for galaxolide and 0.89-0.97 for tonalide with p < 0.003). Galaxolide and tonalide fish tissue concentrations in Germany were ～19× and ～28× lower, respectively, as compared to fish tissue concentrations measured in a United States nationwide PPCP study conducted in 2006. Proximity of the sampling locations to the upstream wastewater treatment plant discharging point and mean annual flow at the sampling location were found to significantly predict galaxolide and tonalide fish tissue concentrations (HHCB: r(2) = 0.79, p = 0.021 and AHTN: r(2) = 0.81, p = 0.037) in Germany.     

Life cycle comparison of environmental emissions from three disposal options for unused pharmaceuticals

We use life cycle assessment methodology to compare three disposal options for unused pharmaceuticals: (i) incineration after take-back to a pharmacy, (ii) wastewater treatment after toilet disposal, and (iii) landfilling or incineration after trash disposal. For each option, emissions of active pharmaceutical ingredients to the environment (API emissions) are estimated along with nine other types of emissions to air and water (non-API emissions). Under a scenario with 50% take-back to a pharmacy and 50% trash disposal, current API emissions are expected to be reduced by 93%. This is within 6% of a 100% trash disposal scenario, which achieves an 88% reduction. The 50% take-back scenario achieves a modest reduction in API emissions over a 100% trash scenario while increasing most non-API emissions by over 300%. If the 50% of unused pharmaceuticals not taken-back are toileted instead of trashed, all emissions increase relative to 100% trash disposal. Evidence suggests that 50% participation in take-back programs could be an upper bound. As a result, we recommend trash disposal for unused pharmaceuticals. A 100% trash disposal program would have similar API emissions to a take-back program with 50% participation, while also having significantly lower non-API emissions, lower financial costs, higher convenience, and higher compliance rates.     

Long-period grating inscription in hydrogen-free SMF-28 fiber by high-repetition-rate femtosecond UV pulses

Using femtosecond UV (258 nm) pulses, generated at high-repetition-rate (50 kHz), we managed to record high-quality long-period gratings in a number of fibers, including a standard telecommunication one, SMF-28. Along with the main grating, connected to the refractive index change in the fiber core, at the relatively high intensity of the inscribing UV radiation, I ～ 1.5 TW/cm², we recorded the formation of an additional long-period grating, based on the refractive index change induced in the fiber cladding. We have compared the temperature sensitivity and the thermal stability of both gratings.     

Programming many‐core architectures ‐ a case study: dense matrix computations on the Intel single‐chip cloud computer processor

A message passing, distributed‐memory parallel computer on a chip is one possible design for future, many‐core architectures. We discuss initial experiences with the Intel Single‐chip Cloud Computer research processor, which is a prototype architecture that incorporates 48 cores on a single die that can communicate via a small, shared, on‐die buffer. The experiment is to port a state‐of‐the‐art, distributed‐memory, dense matrix library, Elemental, to this architecture and gain insight from the experience. We show that programmability addressed by this library, especially the proper abstraction for collective communication, greatly aids the porting effort. This enables us to support a wide range of functionality with limited changes to the library code. Copyright © 2011 John Wiley & Sons, Ltd.     

Skeletal reaction model generation,uncertainty quantification and minimization: Combustion of butane

Skeletal reaction models for n-butane and iso-butane combustion are derived from a detailed chemistry model through directed relation graph (DRG) and DRG-aided sensitivity analysis (DRGASA) methods. It is shown that the accuracy of the reduced models can be improved by optimization through the method of uncertainty minimization by polynomial chaos expansion (MUM-PCE). The dependence of model uncertainty on the model size is also investigated by exploring skeletal models containing different number of species. It is shown that the dependence of model uncertainty is subject to the completeness of the model. In principle, for a specific simulation the uncertainty of a complete model, which includes all reactions important to its prediction, is convergent with respect to the model size, while the uncertainty calculated with an incomplete model may display unpredictable correlation with the model size.     

Solvothermal Synthesis of Acmite Conversion Coatings on Steel

Acmite (NaFeSi₂O₆) films were formed on steel coupons via solvothermal reaction of silica, sodium hydroxide, and 1, 4‐butanediol in an autoclave under autogenous pressure. Systematic variation in processing variables led to homogenous coatings comprised of pinacoidal acmite grains with an average grain size of ~33 μm. The coatings were produced on the steel coupons from reactant conditions of 0.635 m SiO₂, 2.546 m NaOH, and 3.087 m 1,4‐butanediol for 72 h at 240°C.     

医疗电子机柜的冷却和噪声控制

医疗诊断影像设备制造商采用通用机架安装的外壳可以满足越来越复杂和精密的医疗成像系统的要求,从而可将更多精力和投资集中于成像系统本身,而不必为系统的机械外形花费太多。 CPS　Innovations最新系列PET(正电子发射断层) 成像系统就是这样做的。利用模块化方法来解决一系列运行难题,该公司成功地在单个标准电子机柜中集成了更为强大的系统。CPS销售的成像系统非常灵敏,能够提供身体新陈代谢活动的多个截面“快照”。因此,相应的电子外壳解决方案不能牺牲系统性能、耐用性或灵活性,同时还要能够保护内部组件不受热量以及灰尘的影响。 在开发最新PET成像系统时,CPSInnovations开发了一种基本的机柜配置来满足其整个诊断成像系统系列产品的需求。CPS　　Innovations需要外壳足够灵活,支持多种不同的设备配置。在研究了多种外壳解决方案后,C P SInnovations选择了38U配置的Schroff　19英寸Eurorack系列机柜。6英尺高31.5英寸深的Schroff　Eurorack机柜提供了足够的空间,可以容纳整个PET系统和数据处理子系统,同时可以方便地通过标准的房门和通道进行移动。在PET系...     

Effects of 0.1 wt.% Manganese, Aluminum, and Silicon on Oxidation and Copper-rich Liquid Phase Formation in an Iron–0.3 wt.% Copper–0.15 Wt.% Nickel Alloy

This study investigated the effect of easily oxidizable impurities on the oxidation behavior of iron containing small amounts of copper and nickel. The motivation for this work stems from a cracking phenomenon in low carbon steels known as hot shortness. This type of cracking is caused by formation of a copper-rich liquid layer and is reduced in the presence of easily oxidizable impurities. This work studied iron alloys with 0.3 wt.% copper, 0.15 wt.% nickel, and 0.1 wt.% (manganese, aluminum, or silicon) oxidized in air at 1,150 °C. Parabolic oxidation rates were not affected by manganese or aluminum but were decreased with silicon additions. Manganese and aluminum additions led to internal MnO and hercynite formation. These slightly increased the amount of material entrapped into the oxide. Silicon additions led to a nearly continuous fayalite layer near the oxide/metal interface that decreased the oxidation rate and therefore the amount of copper-rich liquid.     

Streptomyces sp.—A Treasure Trove of Weapons to Combat Methicillin-Resistant Staphylococcus aureus Biofilm Associated with Biomedical Devices

Biofilms formed by methicillin-resistant S. aureus (MRSA) are among the most frequent causes of biomedical device-related infection, which are difficult to treat and are often persistent and recurrent. Thus, new and effective antibiofilm agents are urgently needed. In this article, we review the most relevant literature of the recent years reporting on promising anti-MRSA biofilm agents derived from the genus Streptomyces bacteria, and discuss the potential contribution of these newly reported antibiofilm compounds to the current strategies in preventing biofilm formation and eradicating pre-existing biofilms of the clinically important pathogen MRSA. Many efforts are evidenced to address biofilm-related infections, and some novel strategies have been developed and demonstrated encouraging results in preclinical studies. Nevertheless, more in vivo studies with appropriate biofilm models and well-designed multicenter clinical trials are needed to assess the prospects of these strategies.