Silicon vacancy containing two hydrogen atoms studied with electron paramagnetic resonance and infrared absorption spectroscopy, Phys

Float-zone and Czochralski-grown silicon crystals have been implanted with protons or deuterons. Electronparamagnetic-resonance measurements performed during illumination with light at 1064 nm reveal a signal, labeled DK5, in addition to the well-known signal from VO*-the excited spin-triplet state of the oxygenvacancy defect. The DK5 signal originates from a spin-triplet state of a vacancy-type defect with monoclinic-I ͑near-orthorhombic-I͒ symmetry. In contrast to the VO* signal, DK5 has about the same intensity in the spectra recorded on oxygen-lean and oxygen-rich samples, which indicates that the DK5 defect is not oxygen related. However, the close resemblance between the D tensors of DK5 and VO* strongly suggests that the electron-spin distributions are similar in the two defects. Moreover, anisotropic hyperfine splittings from two proton spins are partially resolved in the DK5 signal. The signal is assigned to VH 2 * , the excited spin-triplet state of the silicon vacancy containing two hydrogen atoms, which is the simplest defect consistent with the observed properties. The isochronal annealing behavior of DK5 coincides with that of two infrared-absorption lines at 2063 and 2077 cm Ϫ1 , which, like DK5, are observable only during illumination. These lines are assigned to Si-H stretch modes of VH 2 *

A participatory physical and psychosocial intervention for balancing the demands and resources among industrial workers (PIPPI): study protocol of a cluster-randomized controlled trial

Background: Need for recovery and work ability are strongly associated with high employee turnover, well-being and sickness absence. However, scientific knowledge on effective interventions to improve work ability and decrease need for recovery is scarce. Thus, the present study aims to describe the background, design and protocol of a cluster randomized controlled trial evaluating the effectiveness of an intervention to reduce need for recovery and improve work ability among industrial workers. Methods/Design: A two-year cluster randomized controlled design will be utilized, in which controls will also receive the intervention in year two. More than 400 workers from three companies in Denmark will be aimed to be cluster randomized into intervention and control groups with at least 200 workers (at least 9 work teams) in each group. An organizational resources audit and subsequent action planning workshop will be carried out to map the existing resources and act upon initiatives not functioning as intended. Workshops will be conducted to train leaders and health and safety representatives in supporting and facilitating the intervention activities. Group and individual level participatory visual mapping sessions will be carried out allowing team members to discuss current physical and psychosocial work demands and resources, and develop action plans to minimize strain and if possible, optimize the resources. At all levels, the intervention will be integrated into the existing organization of work schedules. An extensive process and effect evaluation on need for recovery and work ability will be carried out via questionnaires, observations, interviews and organizational data assessed at several time points throughout the intervention period. Discussion: This study primarily aims to develop, implement and evaluate an intervention based on the abovementioned features which may improve the work environment, available resources and health of industrial workers, and hence their need for recovery and work ability

Probing the crossover in CO desorption from single crystal to nanoparticulate Ru model catalysts

cited By 10International audienceUsing model catalysts, we demonstrate that CO desorption from Ru surfaces can be switched from that typical of single crystal surfaces to one more characteristic of supported nanoparticles. First, the CO desorption behaviour from Ru nanoparticles supported on highly oriented pyrolytic graphite was studied. Both mass-selected and thermally evaporated nanoparticles were deposited. TPD spectra from the mass-selected nanoparticles exhibit a desorption peak located around 410 K with a broad shoulder extending from around 480 K to 600 K, while spectra obtained from thermally evaporated nanoparticles exhibit a single broad feature from ∼350 K to ∼450 K. A room temperature deposited 50 Å thick Ru film displays a characteristic nanoparticle-like spectrum with a broad desorption feature at ∼420 K and a shoulder extending from ∼450 K to ∼600 K. Subsequent annealing of this film at 900 K produced a polycrystalline morphology of flat Ru(001) terraces separated by monatomic steps. The CO desorption spectrum from this surface resembles that obtained on single crystal Ru(001) with two large desorption features located at 390 K and 450 K due to molecular desorption from terrace sites, and a much smaller peak at ∼530 K due to desorption of dissociatively adsorbed CO at step sites. In a second experiment, ion sputtering was used to create surface defects on a Ru(0 1 54) single crystal surface. A gradual shift away from the desorption spectrum typical of a Ru(001) surface towards one resembling desorption from supported Ru nanoparticles was observed with increasing sputter time. © 2011 the Owner Societies

Increased renal sodium absorption by inhibition of prostaglandin synthesis during fasting in healthy man. A possible role of the epithelial sodium channels

<p>Abstract</p> <p>Background</p> <p>Treatment with prostaglandin inhibitors can reduce renal function and impair renal water and sodium excretion. We tested the hypotheses that a reduction in prostaglandin synthesis by ibuprofen treatment during fasting decreased renal water and sodium excretion by increased absorption of water and sodium via the aquaporin2 water channels and the epithelial sodium channels.</p> <p>Methods</p> <p>The effect of ibuprofen, 600 mg thrice daily, was measured during fasting in a randomized, placebo-controlled, double-blinded crossover study of 17 healthy humans. The subjects received a standardized diet on day 1, fasted at day 2, and received an IV infusion of 3% NaCl on day 3. The effect variables were urinary excretions of aquaporin2 (u-AQP2), the beta-fraction of the epithelial sodium channel (u-ENaCbeta), cyclic-AMP (u-cAMP), prostaglandin E2 (u-PGE2). Free water clearance (CH2O), fractional excretion of sodium (FENa), and plasma concentrations of vasopressin, angiotensin II, aldosterone, atrial-, and brain natriuretic peptide.</p> <p>Results</p> <p>Ibuprofen decreased u-AQP2, u-PGE2, and FENa at all parts of the study. During the same time, ibuprofen significantly increased u-ENaCbeta. Ibuprofen did not change the response in p-AVP, u-c-AMP, urinary output, and free water clearance during any of these periods. Atrial-and brain natriuretic peptide were higher.</p> <p>Conclusion</p> <p>During inhibition of prostaglandin synthesis, urinary sodium excretion decreased in parallel with an increase in sodium absorption and increase in u-ENaCbeta. U-AQP2 decreased indicating that water transport via AQP2 fell. The vasopressin-c-AMP-axis did not mediate this effect, but it may be a consequence of the changes in the natriuretic peptide system and/or the angiotensin-aldosterone system</p> <p>Trial Registration</p> <p>Clinical Trials Identifier: NCT00281762</p

Growth of the purple dye murex, Bolinus brandaris (Gastropoda: Muricidae), marked and released in a semi-intensive fish culture earthen pond

The present study reports the growth rate of the purple dye murex, Bolinus brandaris (Gastropoda: Muricidae), estimated from mark-recapture experiments. A total of 1067 specimens (shell length = 43.4±8.1 mm, range = 14.6−78.4 mm) were marked with Dymo® tape tags and released in a semi-intensive fish culture earthen pond. After a period at liberty ranging from almost two months to around two years, 288 individuals were recaptured (shell length = 67.4±6.2 mm, range = 45.3−88.6 mm), which corresponded to a recapture rate of 27.0%. At recapture, only one specimen had lost the tag (tag loss rate <0.1%) and all remaining tags were intact and legible. Mean monthly growth rates were 0.9±1.0 mm in shell length, 0.4±0.5 mm in shell width and 0.7±0.7 g in total weight. Growth rates showed high inter-individual variability and an evident decreasing trend with specimen size. Comparison of growth rates with similar information available for other muricids confirmed that B. brandaris is a relatively slow-growing species. This provides valuable information for both fisheries management and for assessing the potential of B. brandaris as a candidate species for molluscan aquaculture.Crecimiento de la cañailla, Bolinus Brandaris (Gastropoda: Muricidae), mediante técnicas de marcado-recaptura realizadas en estanques de cultivo semiintensivo de peces. – Se ha estudiado el crecimiento de la cañailla Bolinus brandaris (Gastropoda: Muricidae) mediante técnicas de marcado-recaptura. Se marcaron un total de 1067 individuos (longitud concha = 43.4±8.1 mm, rango = 14.6−78.4 mm) con etiquetas plásticas Dymo, que fueron puestos en libertad en un estanque en tierra dedicado al cultivo semiintensivo de peces. En el plazo de tiempo comprendido entre dos meses y dos años, se recuperaron 288 ejemplares (longitud concha = 67.4±6.2 mm, rango = 45.3−88.6 mm), lo que corresponde a una tasa de recaptura del 27.0%. Las etiquetas permanecieron intactas y legibles en todos los ejemplares recuperados, a excepción de un único individuo (tasa de pérdida de marca <0.1%). La tasa de crecimiento media mensual estimada fue de 0.9±1.0 mm de longitud, 0.4±0.5 mm de anchura y 0.7±0.7 g de peso total. Esta tasa muestra una elevada variabilidad intraespecífica y una tendencia clara a la disminución con el aumento de la talla. Comparando las tasas de crecimiento obtenidas en este estudio con la información disponible sobre diversas especies de murícidos, se confirma que B. brandaris es un gasterópodo de crecimiento relativamente lento. Este estudio resulta de interés tanto para gestionar la pesca de este recurso como para evaluar el potencial de la especie como candidata a ser cultivada.publishe