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H Samples (h + sample)
Selected AbstractsPassivation study of the amorphous,crystalline silicon interface formed using DC saddle-field glow dischargePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010Barzin Bahardoust Abstract The DC saddle-field (DCSF) glow discharge method was used to deposit intrinsic a-Si:H onto c-Si to passivate the c-Si surface. The effective minority carrier lifetime in the heterostructures as a function of the excess minority carrier density in the c-Si wafers was measured. The results were then analyzed in the context of recombination associated with interface defect states using three known recombination models. The defect density and the charge density at the interface are inferred. In addition subsequent annealing of the samples was studied. It is shown that for our intrinsic a-Si:H samples improvements in surface passivation are directly correlated with the reduction of interface defects and not the reduction of minority carrier concentration at the interface due to electric field. We have achieved excellent surface passivation with effective carrier lifetime >4,ms for an intrinsic a-Si:H sample deposited at a process temperature of 200,°C and thickness of about 30,nm. It is also demonstrated that subsequent annealing, at 240,°C, of the samples which were prepared at process temperatures <240,°C greatly increases the effective lifetime. [source] Annealing effects on crystallized Al-doped a-Ge:H thin filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005F. Fajardo Abstract Annealing effects on crystallized aluminum doped hydrogenated amorphous germanium (a-Ge:H) thin films have been studied by Raman spectroscopy, as a function of Al concentration ([Al/Ge] ,10,6,10,2 range). All the as-deposited Al-doped a-Ge:H samples with [Al/Ge] < 1.3 at% possess a Raman spectra that includes the signal given by the amorphous phase and a shoulder at around 300 cm,1, that evolves with increasing impurity content, to a well defined peak, corresponding to the contribution of the TO vibration of crystallized Ge. The scattering intensity of samples having 1.4 , [Al/Ge] , ,1.8 at% is dominated by the c-Ge TO vibration. Aluminum concentrations above [Al/Ge] > ,1.8 at% do not indicate crystallization of a-Ge:H films to levels detectable by Raman spectroscopy. An abrupt crystallization was observed to occur after annealing at Ta , 500 °C for all the range of the Al-doped samples, including the intrinsic one. These results and the comparison with data of the local order and coordination of Ga atoms into the a-Ge:H network, suggest that Al-induced crystallization originates from fourfold coordinated aluminum atoms that act as crystallization seeds. These seeds have only small influence on the abrupt crystallization of Al doped a-Ge:H films due to annealing treatments. (İ 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High dose methotrexate population pharmacokinetics and Bayesian estimation in patients with lymphoid malignancyBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 8 2009Ye Min Abstract The purpose of present study was to develop a population pharmacokinetic model of high dose methotrexate (HD-MTX) infusion in patients with lymphoid malignancy, to investigate the biological and clinical covariates related to the drug distribution and elimination. It is also the purpose to propose a limited sampling strategy (LSS) for the estimation of the time above the threshold (0.2,µmol·L,1). A total 82 patients with lymphoid malignancy were involved in the study. A pharmacokinetic model was developed using nonlinear mixed-effect model. The influence of demographic characteristics, biological factors, and concurrent administration were investigated. The final predictive performance was validated by bootstrap and cross-validation. Bayesian estimation was evaluated. The pharmacokinetics of HD-MTX was described by a two-compartment model. The pharmacokinetic parameters and the inter-individual variability were as follows: the clearance CL, 7.45,L·h,1 (inter-individual variability 50.6%), the volume of the central and peripheral compartment V1, 25.9,L (22.5%), V2, 9.23,L (97.8%), respectively, and the intercompartmental clearance Q, 0.333,L·h,1 (70.4%). The influence of serum creatinine on CL and weight on V1 was retained in the final model. The protocol involved one sampling time at 44,h after the start of the infusion, allowing one to predict the time at which the MTX concentration reached the expected threshold (0.2,µmol·L,1). Serum creatinine and weight showed significant influence on methotrexate CL and V1, respectively. Furthermore, a Bayesian estimation based on the covariates and 44,h sample was developed, allowing prediction of the individual methotrexate pharmacokinetic parameters and the time to 0.2,µmol·L,1. Copyright İ 2009 John Wiley & Sons, Ltd. [source] Feeding ecology of silverperch, Terapon plumbeus Kner, and the impact of fish-pens in Laguna de Bay, PhilippinesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2000M. Kock Summary Aquaculture is an important factor in the fishery of Laguna de Bay in the Philippines; fish-pens and net-cages covered ,10% of the lake surface in the late 1990s. The present study was carried out to assess the possible influences of aquaculture on a wild fish species, silverperch, Terapon plumbeus Kner, with a special emphasis on the feeding ecology of this fish. For the purposes of the investigation, 24-h samples were taken at 2-month intervals close to a fish-pen as well as in open water over a one-year period to acquire more information on this species. Significant differences in standard length and total weight were found between stations and sampling months. In open water, a mean standard length of 53.6 mm and a mean total weight of 4.2 g were found, whereas close to the fish-pen, the corresponding values were 57.6 mm and 5.4 g, respectively. The maximum mean standard length was attained around December 1996 and February 1997 (59.5 mm in open water; 66.1 mm close to the fish-pen), and the minimum was found in June 1996 (49.1 mm in open water; 46.2 mm close to the fish-pen). Noticeable differences were found in the food spectrum between the two sampling stations. Zooplankton, the major food source at both stations, was more important in the stomach content of fish in open water. The same was true for insects (i.e. chironomid larvae), although these did not make up such a large fraction of the diet. On the other hand, close to the fish-pen, aufwuchs- algae, phytoplankton and fish were more important. Generally, benthic organisms were consumed more frequently close to the fish-pen. Zooplankton was more important in the diet of smaller fish. In all size groups, the importance of zooplankton decreased during the rainy season. [source] Determination of amino acid enantiomers in human urine and blood serum by gas chromatography,mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 3 2001Hans Brückner Amino acid (AA) enantiomers were determined as N(O) -pentafluoropropionyl-(2)-propyl esters by chiral gas chromatography,mass spectrometry (GC-MS) in 24,h samples of the urine of three healthy volunteers and in their blood sera. In urine the largest amounts were determined for D -Ser (64,199,µmol/day) and D -Ala (24,138,µmol/day). In blood sera, D -Ala (2.3,4.2,µmol/L) and D -Ser (1.0,2.9,µmol/L) were most abundant. Varying amounts of the D -enantiomers of Thr, Pro, Asx, Glx, Phe, Tyr, Orn and Lys were also found, albeit not in all urines and sera. Further, enantiomers were quantified in urine samples of two volunteers fasting for 115,h. Quantities of renally excreted D -AAs decreased in fasting, although amounts of D -Ser (69 and 77,µmol/L urine) as well as other D -AAs were still detectable. Time-dependent analyses of urine showed that D -AAs are continuously excreted. Copyright İ 2001 John Wiley & Sons, Ltd. [source] | ||||||||||