DEVELOPMENT OF CURRENT-BASED MICROSCOPIC DEFECT ANALYSIS-METHODS AND ASSOCIATED OPTICAL FILLING TECHNIQUES FOR THE INVESTIGATION ON HIGHLY IRRADIATED HIGH-RESISTIVITY SILICON DETECTORS

Current based microscopic defect analysis methods such as current deep level transient spectroscopy (I-DLTS) and thermally stimulated current (TSC) have been further developed in accordance with the need for the defect analysis of highly irradiated (Phi(n) > 10(13) n/cm(2)) high resistivity silicon detectors. The new I-DLTS/TSC system has a temperature range of 8 K less than or equal to T less than or equal to 450 K and a high sensitivity that can detect a defect concentration of less than 10(10)/cm(3) (background noise as low as 10 fA). A new filling method using different wavelength laser illumination has been applied, which is more efficient and suitable than the traditional voltage pulse filling. It has been found that the filling of a defect level depends on such factors as the total concentration of free carriers generated or injected, the penetration length of the laser (laser wavelength), the temperature at which the filling is taking place, as well as the decay time after the filling (but before the measurement). The mechanism of the defect filling can be explained by the competition between trapping and detrapping of defect levels, possible capture cross section temperature dependence, and interaction among various defect levels in terms of charge transferring. Optimum defect filling conditions have been suggested for highly irradiated high resistivity silicon detectors.

Indoor/outdoor relationships for PM2.5 and associated carbonaceous pollutants at residential homes in Hong Kong - case study

IEECAS SKLLQG

System size dependence of associated yields in hadron-triggered jets STAR Collaboration

We present results on the system size dependence of high transverse momentum di-hadron correlations at root s(NN) = 200 GeV as measured by STAR at RHIC. Measurements in d + Au, Cu + Cu and Au + Au collisions reveal similar jet-like near-side correlation yields (correlations at small angular separation Delta phi similar to 0, Delta eta similar to 0) for all systems and centralities. Previous measurements have shown Chat the away-side (Delta phi similar to pi) yield is suppressed in heavy-ion collisions. We present measurements of the away-side Suppression as a function of transverse momentum and centrality in Cu + Cu and Au + Au collisions. The suppression is found to be similar in Cu + Cu and An + An collisions at a similar number of participants. The results are compared to theoretical calculations based on the patron quenching model and the modified fragmentation model. The observed differences between data and theory indicate that the correlated yields presented here will further constrain dynamic energy loss models and provide information about the dynamic density profile in heavy-ion collisions. (C) 2009 Elsevier B.V. All rights reserved.

Morphology and crystalline transition of poly (3-butylthiophene) associated with its polymorphic modifications

Poly (3-butylthiophene) (P3BT) is a much less studied conjugated polymer despite its high crystallizability and thus excellent electrical property. In this work, morphology of P3BT at different crystalline polymorphs and solvent/thermal induced phase transition between form I and U modifications have been intensively investigated by using optical microscopy, electron microscopy, differential scanning calorimetry, and X-ray diffraction. It is shown that a direct deposition from carbon disulfide (CS2) at fast evaporation results in P3BT crystals in form I modification, giving typical whiskerlike morphology. In contrast, low evaporation rate from CS, leads to formation of form II crystals with spherulitic morphology, which is so far scarcely observed in polythiophene.

Identification, Characterization, and Molecular Application of a Virulence-Associated Autotransporter from a Pathogenic Pseudomonas fluorescens Strain

A gene, pfa1, encoding an autotransporter was cloned from a pathogenic Pseudomonas fluorescens strain, TSS, isolated from diseased fish. The expression of pfa1 is enhanced during infection and is regulated by growth phase and growth conditions. Mutation of pfa1 significantly attenuates the overall bacterial virulence of TSS and impairs the abilities of TSS in biofilm production, interaction with host cells, modulation of host immune responses, and dissemination in host blood. The putative protein encoded by pfa1 is 1,242 amino acids in length and characterized by the presence of three functional domains that are typical for autotransporters. The passenger domain of PfaI contains a putative serine protease (Pap) that exhibits apparent proteolytic activity when expressed in and purified from Escherichia coli as a recombinant protein. Consistent with the important role played by PfaI in bacterial virulence, purified recombinant Pap has a profound cytotoxic effect on cultured fish cells. Enzymatic analysis showed that recombinant Pap is relatively heat stable and has an optimal temperature and pH of 50 degrees C and pH 8.0. The domains of PfaI that are essential to autotransporting activity were localized, and on the basis of this, a PfaI-based autodisplay system (named AT1) was engineered to facilitate the insertion and transport of heterologous proteins. When expressed in E. coli, AT1 was able to deliver an integrated Edwardsiella tarda immunogen (Et18) onto the surface of bacterial cells. Compared to purified recombinant Et18, Et18 displayed by E. coli via AT1 induced significantly enhanced immunoprotection.

Identification and expression of TRAF6 (TNF receptor-associated factor 6) gene in Zhikong Scallop Chlamys farreri

Tumor necrosis factor receptor-associated factor 6 (TRAF6), a key signaling adaptor molecule common to the TNFR superfamily and IL-IR/TLR family, is important not only for a diverse array of physiological processes functions of the TNFR superfamily, but also is involved in adaptive immunity and innate immunity. In this report, the first bivalve TRAF6 (named as CfTRAF6) gene is identified and characterized from Zhikong scallop Chlamys farreri. The full-length cDNA of CfTRAF6 is of 2510 bp, consisting of a 5'-terminal untranslated region (UTR) of 337 bp, a 3'-terminal UTR of 208 bp with a canonical polyadenylation signal sequence AATAAA and a poly (A) tail, and an open reading frame (ORF) encoding a polypeptide of 655 amino acids. The predicted amino acid sequence of CfTRAF6 comprises characteristic motifs of the TRAF proteins, including a Zinc finger of RING-type, two Zinc fingers of TRAF-type, a coiled-coil region, and a MATH (the meprin and TRAF homology) domain. The overall amino acid sequence identity between CfTRAF6 and other TRAF6s is 28-68%. Phylogenetic analyses of CfTRAF6 sequence with TRAF sequences from other organisms indicate that CfTRAF6 is a true TRAF6 orthologue. The mRNA expression of CfTRAF6 in various tissues is measured by Real-time RT-PCR. The mRNA transcripts are constitutively expressed in tissues of haemocyte, muscle, mantle, heart, gonad and gill, but the highest expression is observed in the gonad. The temporal expressions of CfTRAF6 mRNA in the mixed primary cultured haemocytes are recorded after treatment with 20 mu g mL(-1) and 0.5 mu g mL(-1) peptido-glycan (PGN). The expression level of CfTRAF mRNA is down-regulated from 1.5 h to 3 h after the treatment with 0.5 mu g mL(-1) PGN, and then recovers to the original level. While the expression of CfTRAF6 is obviously decreased after treatment with 20 mu g mL(-1) PGN, and reach the lowest point (only about 1/9 times to control) at 3 h. The result Suggests that CfTRAF6 can be greatly regulated by PGN and it may be involved in signal transduction and immune response of scallop. (C) 2008 Published by Elsevier Ltd.

Comparison of two marine sponge-associated Penicillium strains DQ25 and SC10: differences in secondary metabolites and their bioactivities

Two strains of Penicillium, DQ25 and SC10, isolated from marine sponge Haliclona angulata (Bowerbank) and Hymeniacidon sp. respectively, were subjected to stationary cultivation under GYP medium for 30 days. The fermentation extracts were undergone bioactivities assays against human pathogens, phytopathogenic fungi and brine shrimp (Artemia salina). Bioassays-guided compounds isolation was performed by Silica gel columns and Sephadex LH-20 chromatography. Spectroscopic methods were used to structures elucidation of the compounds. Results showed the activities of secondary metabolites of strain DQ25 were generally stronger than that of strain SC10. Major bioactive molecules isolated from strain DQ25 were a 1,4-naphthoquinone derivative and an unidentified alkaloid. The two components were not isolated from the extract of strain SC10. ITS sequences revealed that these two species have the greatest similarity with Penicillium vinaceum and Penicillium granulatum respectively.

Identification and characterization of a virulence-associated protease from a pathogenic Pseudomonas fluorescens strain

Pseudomonas fluorescens is an aquaculture pathogen that can infect a number of fish species. The virulence mechanisms of aquatic P. fluorescens remain largely unknown. Many P. fluorescens strains are able to secrete an extracellular protease called AprX, yet no AprX-like proteins have been identified in pathogenic P. fluorescens associated with aquaculture. In this study, a gene encoding an AprX homologue was cloned from TSS, a pathogenic A fluorescens strain isolated from diseased fish. In TSS, AprX is secreted into the extracellular milieu, and the production of AprX is controlled by growth phase and calcium. Mutation of aprX has multiple effects, which include impaired abilities in interaction with cultured host cells, adherence to host mucus, modulation of host immune response, and dissemination and survival in host tissues and blood. Purified recombinant AprX exhibits apparent proteolytic activity, which is optimal at pH 8.0 and 50 degrees C. The protease activity of recombinant AprX is enhanced by Ca2+ and Zn2+ and reduced by Co2+. Cytotoxicity analyses showed that purified recombinant AprX has profound toxic effect on cultured fish cells. These results demonstrate that AprX is an extracellular metalloprotease that is involved in bacterial virulence. (C) 2009 Elsevier B.V. All rights reserved.