Mechanisms of carrier lifetime enhancement and conductivity-type switching on hydrogen-incorporated arsenicdoped BaSi2

A comparative experimental and theoretical study of the role of H incorporation in As-doped BaSi2 films has been carried out based on the experimental results that an optimal time of H treatment for the increase in photoresponsivity and carrier lifetime was in the range of 1 – 20 min. Adequate theoretical representation of the decay curves in the framework of the model for non-radiative processes accounted for various trap-related recombination mechanisms to estimate the trap concentration to be in the range of 1.9 × 1013 to 1.7 × 1014 cm-3. Additionally, the extended theoretical ab initio quantum-chemical simulation of the electronic structure of the studied systems was performed. It was revealed that interstitial As atoms can mostly provide trap states in the gap while H atoms neutralize such traps. The experimentally observed unexpected switching in conductivity from n-type to p-type and vice versa in As-doped BaSi2 with H incorporation was explained to specific configurations of point defects (an As impurity with a H atom in different positions and various interatomic As-H distances) which affect the position of states in the gap

Protective effect of geranylgeranylacetone, an inducer of heat shock protein 70, against drug-induced lung injury/fibrosis in an animal model

<p>Abstract</p> <p>Background</p> <p>To determine whether oral administration of geranylgeranylacetone (GGA), a nontoxic anti-ulcer drug that is an inducer of heat shock protein (HSP) 70, protects against drug-induced lung injury/fibrosis <it>in vivo</it>.</p> <p>Methods</p> <p>We used a bleomycin (BLM)-induced lung fibrosis model in which mice were treated with oral 600 mg/kg of GGA before and after BLM administration. Inflammation and fibrosis were evaluated by histological scoring, hydroxyproline content in the lung and inflammatory cell count, and quantification by ELISA of macrophage inflammatory protein-2 (MIP-2) in bronchoalveolar lavage fluid. Apoptosis was evaluated by the TUNEL method. The induction of HSP70 in the lung was examined with western blot analysis and its localization was determined by immunohistochemistry.</p> <p>Results</p> <p>We confirmed the presence of inflammation and fibrosis in the BLM-induced lung injury model and induction of HSP70 by oral administration of GGA. GGA prevented apoptosis of cellular constituents of lung tissue, such as epithelial cells, most likely related to the <it>de novo </it>induction of HSP70 in the lungs. GGA-treated mice also showed less fibrosis of the lungs, associated with the findings of suppression of both production of MIP-2 and inflammatory cell accumulation in the injured lung, compared with vehicle-treated mice.</p> <p>Conclusion</p> <p>GGA had a protective effect on drug-induced lung injury/fibrosis. Disease-modifying antirheumatic drugs such as methotrexate, which are indispensable for the treatment of rheumatoid arthritis, often cause interstitial lung diseases, an adverse event that currently cannot be prevented. Clinical use of GGA for drug-induced pulmonary fibrosis might be considered in the future.</p

‘A phase II study of oral uracil/ftorafur (UFT®) plus leucovorin combined with oxaliplatin (TEGAFOX) as first-line treatment in patients with metastatic colorectal cancer'

This phase II trial was performed to evaluate the efficacy and tolerability of a new combination of Uracil/Ftorafur (UFT®)/leucovorin (LV) and oxaliplatin in patients (pts) with metastatic colorectal cancer (MCRC) who had not received prior chemotherapy for metastatic disease. Between February 2002 and October 2002, 64 patients received UFT® 300 mg m−2 day−1 and LV 90 mg day−1 from day 1 to day 14 combined with oxaliplatin 130 mg m−2 on day 1, every 3 weeks. All patients were evaluable for safety analysis and 58 of 64 patients were eligible for efficacy. Responses were reviewed by an independent review committee. Of the 58 per-protocol defined assessable patients, 1 complete response and 20 partial responses were observed yielding a response rate of 34% (95% CI: 22–47). The median response duration was 8.74 months (range 1.6–14). The median time to progression and the median survival were 5.88 months (95% CI: 4.34–8.21) and 18.2 months (95% CI: 10–20.7), respectively. Diarrhoea and peripheral neuropathy were the most frequent and predictable toxicities. These events were reversible, noncumulative and manageable. Grade 3 diarrhoea occurred in only 11% of the patients. No grade 4 gastrointestinal toxicity was reported in the study. The incidence of grade 3/4 (National Cancer Institute Common Toxicity Criteria 2: NCI-CTC 2) peripheral neuropathy was 15%. Haematological toxicity was of mild to moderate intensity with 10% of the patients with Grade 3/4 neutropenia without any episode of complication. The TEGAFOX regimen, a new combination using UFT®/LV and oxaliplatin every 3 weeks is feasible on an outpatient basis. The combination is safe and active and may offer a promising alternative to the intravenous route. Nevertheless this efficacy results should be confirmed by randomized phase III trials

Marked enhancement of the photoresponsivity and minority-carrier lifetime of BaSi2 passivated with atomic hydrogen

Passivation of barium disilicide (BaSi2) films is very important for their use in solar cell applications. In this paper, we demonstrated the effect of hydrogen (H) passivation on both the photoresponsivity and minority-carrier lifetime of BaSi2 epitaxial films grown by molecular beam epitaxy. First, we examined the growth conditions of a 3-nm-thick hydrogenated amorphous silicon (a-Si) capping layer formed on a 500-nm-thick BaSi2 film and found that an H supply duration (ta-Si:H) of 15 min at a substrate temperature of 180 °C sizably enhanced the photoresponsivity of the BaSi2 film. We next supplied atomic H to BaSi2 epitaxial films at 580 °C and changed supply duration (tBaSi;H) in the range of 1–30 min, followed by capping with an a-Si layer. The photoresponsivity of the films changed considerably depending on tBaSi;H and reached a maximum of 2.5 A/W at a wavelength of 800 nm for the sample passivated for tBaSi;H = 15 min under a bias voltage of 0.3 V applied to the front-surface indium-tin-oxide electrode with respect to the back-surface aluminum electrode. This photoresponsivity is approximately one order of magnitude higher than the highest value previously reported for BaSi2. Microwave photoconductivity decay measurements revealed that the minority-carrier lifetime of the BaSi2 film with the highest photoresponsivity was 14 μs, equivalent to its bulk carrier lifetime ever reported. We performed theoretical analyses based on a rate equation including several recombination mechanisms and reproduced the experimentally obtained decay curves. We also calculated the total density of states of BaSi2 by ab initio studies when one Si vacancy existed in a unit cell and one, two, and three H atoms occupied Si vacancy or interstitial sites. A Si vacancy caused a localized state with two energy bands to appear close to the middle of the band gap. In certain cases, H passivation of the Si dangling bonds can markedly decrease trap concentration. From both experimental and theoretical viewpoints, we conclude that an atomic H supply is beneficial for BaSi2 solar cells

Modelling Strategies for Predicting the Residual Strength of Impacted Composite Aircraft Fuselages

Aeronautic Certification rules established for the metallic materials are not convenient for the composite structures concerning the resistance against impact. The computerbased design is a new methodology that is thought about to replace the experimental tests. It becomes necessary for numerical methods to be robust and predictive for impact. Three questions are addressed in this study: (i) can a numerical model be “mechanically intrinsic” to predict damage after impact, (ii) can this model be the same for a lab sample and a large structure, and (iii) can the numerical model be predictive enough to predict the Compression After Impact (CAI)? Three different computational strategies are used and compared: a Cohesive Model (CM), a Continuous Damage Model (CDM) coupling failure modes and damage, and a Mixed Methodology (MM) using the CDM for delamination initiation and the CM for cracks propagation. The first attempts to use the Smooth Particle Hydrodynamics method are presented. Finally, impact on a fuselage is modelled and a numerical two-stage strategy is developed to predict the CAI