Pore size distribution and supercritical hydrogen adsorption in activated carbon fibers

Pore size distributions (PSD) and supercritical H_2 isotherms have been measured for two activated carbon fiber (ACF) samples. The surface area and the PSD both depend on the degree of activation to which the ACF has been exposed. The low-surface-area ACF has a narrow PSD centered at 0.5 nm, while the high-surface-area ACF has a broad distribution of pore widths between 0.5 and 2 nm. The H_2 adsorption enthalpy in the zero-coverage limit depends on the relative abundance of the smallest pores relative to the larger pores. Measurements of the H_2 isosteric adsorption enthalpy indicate the presence of energy heterogeneity in both ACF samples. Additional measurements on a microporous, coconut-derived activated carbon are presented for reference

The Bio-Politics of Population Control and Sex Selective Abortion in China and India

China and India, two countries with skewed sex ratios in favor of males, have introduced a wide range of policies over the past few decades to prevent couples from deselecting daughters, including criminalizing sex-selective abortion through legal jurisdiction. This article aims to analyze how such policies are situated within the bio-politics of population control and how some of the outcomes reflect each government’s inadequacy in addressing the social dynamics around abortion decision making and the social, physical, and psychological effects on women’s wellbeing in the face of criminalization of sex-selective abortion. The analysis finds that overall, the criminalization of sex selection has not been successful in these two countries. Further, the broader economic, social, and cultural dynamics which produce bias against females must be a part of the strategy to combat sex selection, rather than a narrow criminalization of abortion which endangers women’s access to safe reproductive health services and their social, physical, and psychological wellbeing

Adsorption and melting of hydrogen in potassium-intercalated graphite

Volumetric adsorption and quasielastic neutron scattering are used to study the diffusion and thermodynamics of sorbed H_2 in the graphite intercalation compound KC24. A sorption enthalpy of 8.5 kJ/mol at zero coverage is determined from H_2 adsorption isotherms. From measurements of total elastic-neutron-scattering intensity as a function of temperature, a melting transition of the H_2 adsorbate is observed at 35 K for KC_(24)(H_2)_1. Quasielastic-neutron-scattering (QENS) spectra reveal distinct slow- and fast-H_2-diffusion processes which exist simultaneously at temperatures above the transition point. The temperature dependence of the characteristic diffusion times follows an Arrhenius relation tau=tau_0 exp(E_a/T), where tau_0^(fast)=1.0±0.1 ps, tau_0^(slow)=21±2 ps, E_a^(fast)=156±5 K, and E_a^(slow)=189±5 K. The fast-diffusion process is attributable to individual motions of H_2 molecules in a static potassium structure, and the slow-diffusion process could be attributable to fluctuations in H_2 particle density correlated with jumps of potassium atoms. The QENS spectra at low Q are used to discuss the dimensionality of the diffusion process

EHV-1 gene63 is not essential for in vivo replication in horses and mice, nor does it affect reactivation in the horse: Short Communication

The aim of this study was to investigate the role of immediate early gene (gene63) in the pathogenesis of equine herpesvirus 1 (EHV-1) acute and latent infections in equine and murine models. EHV-1 gene63 mutant virus (g63mut) along with EHV-1 (Ab4) was used for intracerebral and intranasal infection of 3 and 17-day-old mice. Both viruses were recovered at the same frequency from tissues after infection. Two Welsh ponies were infected via the intranasal route with each of the viruses. Acute infection was monitored by virus isolation from nasal swabs and peripheral blood leukocytes. Six weeks post infection, peripheral blood leukocytes were taken from ponies and in vitro reactivation was positive for both viruses. At autopsy, both viruses were isolated by co-cultivation from bronchial and submandibular lymph nodes. These findings indicate that the mutation of EHV-1 gene63 does not play a role in the establishment and reactivation from latency

Hydrogen diffusion in potassium intercalated graphite studied by quasielastic neutron scattering

The graphite intercalation compound KC24 adsorbs hydrogen gas at low temperatures up to a maximum stoichiometry of KC_(24)(H_2)_2, with a differential enthalpy of adsorption of approximately −9 kJ mol^(−1). The hydrogen molecules and potassium atoms form a two-dimensional condensed phase between the graphite layers. Steric barriers and strong adsorption potentials are expected to strongly hinder hydrogen diffusion within the host KC_24 structure. In this study, self-diffusion in a KC_(24)(H_2)_0.5 sample is measured experimentally by quasielastic neutron scattering and compared to values from molecular dynamics simulations. Self-diffusion coefficients are determined by fits of the experimental spectra to a honeycomb net diffusion model and found to agree well with the simulated values. The experimental H2 diffusion coefficients in KC_24 vary from 3.6 × 10^(−9) m^2 s^(−1) at 80 K to 8.5 × 10^(−9) m^2 s^(−1) at 110 K. The measured diffusivities are roughly an order of magnitude lower that those observed on carbon adsorbents, but compare well with the rate of hydrogen self-diffusion in molecular sieve zeolites

Determination of Arsenic, Mercury and Barium in herbarium mount paper using dynamic ultrasound-assisted extraction prior to atomic fluorescence and absorption spectrometry

A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic Flourescence spectrometers as detectors was developed to analyse mercury, arsenic and barium from herbarium mount paper originating from the herbarium collection of the National Museum of Wales. The variables influencing extraction were optimised by a multivariate approach. The optimal conditions were found to be 1% HNO3 extractant solution used at a flow rate of 1 mL min-1. The duty cycle and amplitude of the ultrasonic probe was found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance between the probe and the top face of the extraction chamber was found to be 0 cm. Under these conditions the time required for complete extraction of the three analytes was 25 min. Cold vapour and hydride generation coupled to atomic fluorescence spectrometry was utilized to determine mercury and arsenic, respectively. The chemical and instrumental conditions were optimized to provide detection limits of 0.01ng g-1 and 1.25 ng g-1 for mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic absorption spectrometry, with a detection limit of 25 ng g-1. By using 0.5 g of sample, the concentrations of the target analytes varied for the different types of paper and ranged between 0.4–2.55 µg g-1 for Ba, 0.035–10.47 µg g-1 for As and 0.0046–2.37 µg g-1 for Hg

Adolescents' judgments of doubly deviant peers: Implications of intergroup and intragroup dynamics for disloyal and overweight group members

Group membership, loyalty, and weight are highly relevant for adolescent peer evaluations at school. This research tested how in‐group/out‐group membership affected judgments of peers who deviated from social norms for weight and loyalty. Two hundred and forty 11–13‐year‐olds (49 percent female; 94 percent Caucasian) judged two in‐group or out‐group peers: one was normative (loyal and average weight) and the other was non‐normative (i.e., ‘deviant’). The deviant target was overweight, disloyal to their own group (school), or both (‘doubly deviant’). Derogation of overweight relative to average weight peers was greater if they were in‐group rather than out‐group members, revealing a strong ‘black sheep effect’ for overweight peers. Disloyal out‐group deviants were judged favorably, but this effect was eliminated if they were doubly deviant, suggesting that their disloyalty was insufficient to overcome the overweight stigma. Consistent with developmental subjective group dynamics theory, effects of group membership and types of deviance on adolescents’ favorability toward peers were mediated by adolescents’ perceptions of how well the deviant members would ‘fit’ with the in‐group school. Implications for theory and strategies to reduce peer exclusion, particularly weight stigmatization, are considered

Landau Level Splitting in Graphene in High Magnetic Fields

The quantum Hall (QH) effect in two-dimensional (2D) electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T. QH plateaus at filling factors $\nu=0,\pm 1,\pm 4$ are discovered at magnetic fields $B>$20 T, indicating the lifting of the four-fold degeneracy of the previously observed QH states at $\nu=\pm(|n|+1/2)$, where $n$ is the Landau level index. In particular, the presence of the $\nu=0, \pm 1$ QH plateaus indicates that the Landau level at the charge neutral Dirac point splits into four sublevels, lifting sublattice and spin degeneracy. The QH effect at $\nu=\pm 4$ is investigated in tilted magnetic field and can be attributed to lifting of the spin-degeneracy of the $n=1$ Landau level.Comment: 11 pages including 4 figures, to appear in PR

MOF-5 composites exhibiting improved thermal conductivity

Metal-organic frameworks MOF-5 Thermal conductivity Surface area a b s t r a c t The low thermal conductivity of the prototype hydrogen storage adsorbent, metal-organic framework 5 (MOF-5), can limit performance in applications requiring rapid gas uptake and release, such as in hydrogen storage for fuel cell vehicles. As a means to improve thermal conductivity, we have synthesized MOF-5-based composites containing 1e10 wt.% of expanded natural graphite (ENG) and evaluated their properties. Cylindrical pellets of neat MOF-5 and MOF-5/ENG composites with densities of 0.3, 0.5, and 0.7 g/cm 3 are prepared and assessed with regard to thermal conductivity, specific heat capacity, surface area, and crystallinity. For pellets of density w0.5 g/cm Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Metal-organic framework 5 (MOF-5) is a microporous, crystalline solid comprised of 1, Regarding gas storage, MOF-5 has been extensively studied for automotive hydrogen storage applications [1,7e10,15,16]. This interest stems from the observation that MOF-5 can adsorb a large amount of hydrogen, up to 7.1 excess wt.% at 77 K and 40 bar With conventional synthesis methods, MOF-5 is obtained as a loose powder consisting of small cubic crystallites (<1 mm) with low bulk density (r ¼ 0.13 g/cm 3 ) E-mail addresses: [email protected] (J. Yang), [email protected] (D.J. Siegel). Available online at www.sciencedirect.com journal h om epa ge: www.elsev ier.com/locate/he i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 6 1 0 9 e6 1 1