The effect of oxidation on the surface chemistry of sulfur-containing carbons and their arsine adsorption capacity

Two carbons with different sulfur contents were prepared and oxidized either by heating in air or by chemical treatment. The samples were then tested as adsorbents of arsine in dynamic conditions at room temperature, both in dry conditions and in the presence of moisture. Chemical and structural features of the initial and arsine-exposed materials were analyzed by energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analyses, sorption of nitrogen and sorption of water. It was found that oxygen- and sulfur-containing groups participate in arsine oxidation to arsenic tri- and pentoxide and/or in the formation of arsenic sulfides. This occurred either via activation of oxygen or a direct involvement of these groups in reactions with arsine. A very hydrophilic surface of sulfur-containing carbons, which causes the presence of adsorbed water, even in dry conditions, enhances arsine removal. On the other hand, in moist conditions water totally occupies the pore system blocking the catalytic action of the surface toward oxidation, which leads to a very limited or zero AsH₃ adsorption capacity.     

Performance of a newly developed hydrophilic additive blended with different ultrafiltration base polymers

The capability of modifying ultrafiltration (UF) membranes with different base‐polymers using a newly synthesized hydrophilic additive was investigated in this study. Five typical base‐polymers were tested: cellulose acetate (CA), polyetherimide (PEI), polyethersulfone (PES), polysulfone (PS), and polyvinylidene fluoride (PVDF). The changes in characteristics and performance of the membranes were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle analysis, and solute transport tests. It was found that the effect of the hydrophilic additive was different for each polymer. Higher additive contents resulted in higher permeation flux. A visible effect on water content and permeability was obtained but the impact was not shown clearly in contact angles, possibly the additive's concentration was not sufficiently high at the surface. In term of flux enhancement the PES and PVDF membranes benefited the most by the addition of the hydrophilic additive. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

U.S. College Students' Internet Use: Race, Gender and Digital Divides

The goal of this study was to learn about whether race and gender make a difference in Internet use among U.S. college students. A survey of college students at 40 U.S. higher education institutions was conducted, along with observations and interviews at several Midwestern U.S. universities. For comparison to the general U.S. population a nationwide telephone survey was undertaken. The study presents new data on Internet use among male and female college students, as well as trends in use across racial lines. Data on non-White Hispanic college student users of the Internet provides insight into Internet use among a group that appears to be underrepresented in the literature on college students and Internet use. The data analysis presents a complex picture of differential Internet use along gender lines, one that is generally consistent with the existing scholarly literature. Differential use based on race is a bit more complex. Stronger points of contrast emerge amongst White non-Hispanic, Hispanic, and Black non-Hispanic college students than they do when the respondents are grouped by gender.     

Contribution of relay intercropping with legume cover crops on nitrogen dynamics in organic grain systems

Nitrogen (N) management is a key issue in livestock-free organic grain systems. Relay intercropping with a legume cover crop can be a useful technique for improving N availability when two cash crops are grown successively. We evaluated the benefits of four relay intercropped legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) on N dynamics and their contribution to the associated and subsequent cash crops in six fields of organic farms located in South-East France. None of the relay intercropped legumes affected the N uptake of the associated winter wheat but all significantly increased the N uptake of the succeeding spring crop, either maize or spring wheat. The improvement of the N nutrition of the subsequent maize crop induced a 30 % increase in grain yield. All relay intercropped legumes enriched the soil–plant system in N through symbiotic fixation. From 71 to 96 % of the N contained in the shoots of the legumes in late autumn was derived from the atmosphere (Ndfa) and varied between 38 and 67 kg Ndfa ha^?1. Even if the cover crop is expected to limit N leaching during wintertime, the presence of relay intercropped legumes had no significant effect on N leaching during winter compared to the control.     

Computerized histomorphometric study of the splenic collagen polymorphism: A control‐tissue for polarization microscopy

Previous articles have pointed out the presence of type III collagen within the extracellular structure of the parenchymatous organs. This study aimed to quantitatively characterize the collagen polymorphism at the capsule and parenchymal trabeculae of the largest lymphoid organ of the body i.e., the spleen, in mouse, rat, and rabbit models. Following a Picrosirius Red‐Polarization procedure and computer assisted image analysis of paraffin sections, the results showed (1) a predominant and significantly higher amount of type III collagen in the trabeculae area compared to the capsule area in the three species, (2) no statistical difference among the three species concerning the parenchymal collagen polymorphism or the type I/type III collagen ratio, (3) a heterogeneous type I/type III collagen ratio varying from 0.86 (mouse) to 6.62 (rabbit) in the fibromuscular capsule region. A qualitative analysis corroborated these histomorphometric results. In conclusion, the spleen may be used as (1) a control tissue to qualitatively visualize type I and III collagen under polarization microscopy and to validate the quality of PSR staining (2) an aid to accurately calibrate the angle of polarization before quantitative measurements of type I and type III collagen. Among the studied species, the rabbit spleen appeared to be the most appropriate control tissue as it showed the highest amount of type I collagen in the capsule and a similarly high amount of type III collagen in the parenchymal trabeculae. Microsc. Res. Tech. 78:900–907, 2015. © 2015 Wiley Periodicals, Inc.     

Fine‐Tuning of Superhydrophobicity Based on Monolayers of Well‐defined Raspberry Nanoparticles with Variable Dual‐roughness Size and Ratio

Superhydrophobic surfaces have been extensively investigated for self‐cleaning, low‐adhesion, anti‐corrosion or reduced‐drag applications. Roughness and its characteristics, i.e., morphology, overall roughness and individual feature size, is an essential factor for superhydrophobicity. Several experimental methods and theoretical models strived to predict how the surface wettability is affected by the surface roughness. However, due to the difficulty of making practical surfaces with well‐defined roughness profiles, only limited and arbitrary experimental studies focused on practical superhydrophobic films. Here, the roughness factors which determine the wetting properties of films are reported, based on monolayers of well‐defined raspberry silica‐silica nanoparticles, exhibiting a wide‐range and systematic variation of individual features sizes and ratios (large over small features). The advancing water contact angle does not depend on the feature size or ratio, while the contact angle hysteresis (CAH) is strongly dependent on both. The minimum size and size ratio to reach superhydrophobicity were determined. These new insights into the wetting of rough surfaces can be used to direct the design of practical superhydrophobic materials for advanced applications such as solar panels, microelectronics or microfluidic devices.     

The time course of grief reactions to spousal loss: Evidence from a national probability sample.

Most studies of widowhood have focused on reactions during the first few years postloss. The authors investigated whether widowhood had more enduring effects using a nationally representative U.S. sample. Participants were 768 individuals who had lost their spouse (from a few months to 64 years) prior to data collection. Results indicated that the widowed continued to talk, think, and feel emotions about their lost spouse decades later. Twenty years postloss, the widowed thought about their spouse once every week or 2 and had a conversation about their spouse once a month on average. About 12.6 years postloss, the widowed reported feeling upset between sometimes and rarely when they thought about their spouse. These findings add to an understanding of the time course of grief. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydrodynamic Changes in Sand due to Biogrowth on Naphthalene and Decane

Biological activity in zones of chemical contamination changes the pore characteristics that control the flow of water and transport of dissolved chemicals in soils. To further the understanding of these processes, column experiments were performed to evaluate the effect of biomass growth on decane or naphthalene dissolved in simulated groundwater on the hydraulic conductivity and dispersivity of sand. The effect of grain size, groundwater flowrate, and nitrogen limitation were investigated. Given the low carbon loading resulting from the solubility of decane and naphthalene, sparse and discontinuous biomass growth reduced the hydraulic conductivity of the sand by 2 to 3 orders of magnitude after 35 to 63 days. This biogrowth initially increased dispersivity of the sand, but after longer periods of growth dispersivity, decreased to stable values near that of the clean sand. The results indicate that biogrowth can have significant effects in natural systems with low carbon loading and nitrogen availability, and should be taken into account when using models to predict contaminant transport in the field.