Materials science and applications of solid crystals

AbstractProfessor Robert Triboulet from CNRS, France and Professor Antoni Rogalski from the Institute of Applied Physics, Military University of Technology in Warsaw, Poland report on the ”Second International Conference on Solid State Crystals (ICSSG)-Material Science and Applications“, which was held in Zakopane, Poland, 9-13 October and covered developments in bulk crystal growth of GaN and CdZnTe, infra-red detectors for thermal imaging arrays on cars, and two-colour QWIP detectors

Simulation and analysis of a digital scanning system

The analysis and simulation of the motion of a digitally-controlled digital imaging system is presented. The dynamic system consists of a scanning carriage, power transmission elements, a prime mover, and a control subsystem. The prime mover is a permanent magnet DC motor that is positioned by a direct digital control system. The scan carriage motion is mathematically modeled and simulated using ACSL and DADS simulation software. T he simulation results are compared to empirical data. It is shown that the dynamic response of the actual scan system can be predicted quite well using such simulations. Furthermore, these simulations can aid in the design of vibration-sensitive image formation devices

Local adaptation of a parasite to solar radiation impacts disease transmission potential, spore yield, and host fecundity*

Environmentally transmitted parasites spend time in the abiotic environment, where they are subjected to a variety of stressors. Learning how they face this challenge is essential if we are to understand how host–parasite interactions may vary across environmental gradients. We used a zooplankton–bacteria host–parasite system where availability of sunlight (solar radiation) influences disease dynamics to look for evidence of parasite local adaptation to sunlight exposure. We also examined how variation in sunlight tolerance among parasite strains impacted host reproduction. Parasite strains collected from clearer lakes (with greater sunlight penetration) were most tolerant of the negative impacts of sunlight exposure, suggesting local adaptation to sunlight conditions. This adaptation came with both a cost and a benefit for parasites: parasite strains from clearer lakes produced relatively fewer transmission stages (spores) but these strains were more infective. After experimental sunlight exposure, the most sunlight‐tolerant parasite strains reduced host fecundity just as much as spores that were never exposed to sunlight. Sunlight availability varies greatly among lakes around the world. Our results suggest that the selective pressure sunlight exposure exerts on parasites may impact both parasite and host fitness, potentially driving variation in disease epidemics and host population dynamics across sunlight availability gradients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156433/3/evo13940.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156433/2/evo13940-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156433/1/evo13940_am.pd

Gamma radiation exposure of MCT diode arrays

Investigations of electrical properties of long-wavelength infrared (LWIR) mercury cadmium telluride (MCT) arrays exposed to gamma-radiation have been performed. Resistance-area product characteristics of LWIR n{+}-p photodiodes have been investigated using microprobe technique at T=78 K before and after an exposure to various doses of gamma-radiation. The current transport mechanisms for those structures are described within the framework of the balance equation model taking into account the occupation of the trap states in the band gap.Comment: 11 pages, 4 figures, submitted to Semiconductor Science and Technolog

Florula da ilha de Moleques do Sul, Santa Catarina, Brasil

The floristic study of “Moleques do Sul” Island (Santa Catarina, Brazil), was carried out from May/2003 to September/2004. The collected material was dried and included at HLS herbarium (UNIVALI). Twenty-four species, congregated in 18 botanical families, have been identified. Fifteen new occurrences were registered for the island. Fabaceae was the best represented family. The species most widely distributed was Verbesina glabrata Hook. & Arn. (Asteraceae).The floristic study of “Moleques do Sul” Island (Santa Catarina, Brazil), was carried out from May/2003 to September/2004. The collected material was dried and included at HLS herbarium (UNIVALI). Twenty-four species, congregated in 18 botanical families, have been identified. Fifteen new occurrences were registered for the island. Fabaceae was the best represented family. The species most widely distributed was Verbesina glabrata Hook. & Arn. (Asteraceae)

Formation and action of lignin-modifying enzymes in cultures of Phlebia radiata supplemented with veratric acid

Transformation of veratric (3,4-dimethoxybenzoic) acid by the white rot fungus Phlebia radiata was studied to elucidate the role of ligninolytic, reductive, and demeth(ox)ylating enzymes. Under both air and a 100% O2 atmosphere, with nitrogen limitation and glucose as a carbon source, reducing activity resulted in the accumulation of veratryl alcohol in the medium. When the fungus was cultivated under air, veratric acid caused a rapid increase in laccase (benzenediol:oxygen oxidoreductase; EC 1.10.3.2) production, which indicated that veratric acid was first demethylated, thus providing phenolic compounds for laccase. After a rapid decline in laccase activity, elevated lignin peroxidase (ligninase) activity and manganese-dependent peroxidase production were detected simultaneously with extracellular release of methanol. This indicated apparent demethoxylation. When the fungus was cultivated under a continuous 100% O2 flow and in the presence of veratric acid, laccase production was markedly repressed, whereas production of lignin peroxidase and degradation of veratryl compounds were clearly enhanced. In all cultures, the increases in lignin peroxidase titers were directly related to veratryl alcohol accumulation. Evolution of 14CO2 from 3-O14CH3-and 4-O14CH3-labeled veratric acids showed that the position of the methoxyl substituent in the aromatic ring only slightly affected demeth(ox)ylation activity. In both cases, more than 60% of the total 14C was converted to 14CO2 under air in 4 weeks, and oxygen flux increased the degradation rate of the 14C-labeled veratric acids just as it did with unlabeled cultures

Room temperature mid-infrared InAsSbN multi-quantum well photodiodes grown by MBE

Room temperature photoresponse in the mid-infrared spectral region is demonstrated from InAsSbN/InAs multi-quantum well photodiodes grown by nitrogen plasma assisted molecular beam epitaxy. The structural quality of the InAsSbN MQWs was ascertained in situ by reflection high energy electron diffraction and ex situ by high resolution x-ray diffraction and photoluminescence measurements. The extended long wavelength photoresponse is identified to originate from the electron–heavy hole (e1–hh1) and electron–light hole (e1–lh1) transitions in the InAsSbN MQW, with a cut off wavelength ~4.20 µm and peak detectivity D *  =  1.25  ×  109 cm Hz1/2 W−1