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We have evaluated the total-ionizing-dose response of graphene-based X-ray detectors fabricated from graphene oxide (GO) via laser scribing. Raman characterization shows that the resulting structures exhibit the desired conversion of GO to graphene; both high- and low-resistance detectors are formed. The detectors are quite radiation sensitive, as demonstrated by fast pulse testing. The response time of the detectors degrades with total-ionizing dose exposure as a result of electron trapping at residual oxygen from unreacted GO and/or adsorbed oxygen on the graphene surface. [ABSTRACT FROM PUBLISHER]

OBJECTIVE: Helicobacter pylori is documented to have infected more than half of the world’s population. It colonizes the human stomach and is associated with the development of chronic active gastritis, peptic ulcer disease, gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Immunization against this bacterium represents a cost-effective strategy to reduce global gastric cancer rates and would have a major impact on H. pylori -related peptic ulcer disease. HpaA, a subunit protein of H. pylori adhesin, is known to be the pathogenic factor and attenuated Salmonella typhimurium is a live vaccine vector. The present study aimed at constructing and identifying a live attenuated S. typhimurium vaccine carrying the hpaA gene of H. pylori.. METHODS: The hpaA gene was amplified from H. pylori genomic DNA by polymerase chain reaction (PCR) and cloned into the Nco I-Sal I site of the prokaryotic expression plasmid pTrc99A. After sequence analysis of the hpaA gene, the identified recombinant plasmid was then used to transform a live attenuated S. typhimurium , namely SL3261, and positive clones were screened by PCR and restriction enzyme digestion. RESULTS: Confirmed by PCR, restriction enzyme digestion and sequence analysis, a recombinant prokaryotic expression plasmid, namely pTrc99A-hpaA, harboring approximately 560 bp hpaA was constructed and the recombinant plasmid was then successfully introduced into a live attenuated S. typhimurium SL3261. CONCLUSION: A recombinant live attenuated S. typhimurium vaccine harboring the H. pylori hpaA gene was constructed and identified. This work will help develop an oral recombinant live vaccine against H. pylori infection. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of AZ91–SiC nanocomposites processed by cyclic closed-die forging were investigated. The results showed that much finer grain size and more homogeneous distribution of Mg17Al12 phase and SiC nanoparticles were obtained along with significant improvement in strength and elongation after five passes. During cyclic closed-die forging processing, the agglomeration of nanoparticles disintegrated through kneading effect induced by intense matrix flow, and the nano-sized SiC particles were dispersed uniformly into the matrix. However, a few SiC clusters still existed due to the high surface energy of nanoparticles. Properties enhancement of the composites was mainly attributed to Hall–Petch effect and Orowan strengthening. [ABSTRACT FROM AUTHOR]