Preparation of copper single crystals by means of powder metallurgy methods

Since different mechanical properties of metals result from different grain size became known, the metallurgists have been interested in finding out the true nature of the grain boundaries. Consequently, several different theories concerning the mechanism of recrystallization, grain growth, and the structure of metals were advanced and studied. These threw much light on the difference of properties between polycrystalline metals and single crystals of the same metals. The single crystals of metals were studied because they enabled the investigator to determine the important points of metallic behavior. The first work on single crystals was rather obscure and limited to isolated, though significant, observations on native metals and on large grains which were removed from severely coarsened metal parts. The aim of the present research was to investigate the possibility of preparing the single crystals from copper powder by employing the powder metallurgy technique. However, the principal differences between cast and sintered metals are the relative weakness of the adhesive forces between particles and the presence of pores between them in the case of powder compacts. The factors controlling grain growth and grain size for powder compacts depend not only upon the amount of deformation, temperature and time of annealing, but also depend upon the amount of compressing pressure and the sintering conditions of powder compacts --Introduction, page 1

High and Increasing Oxa-51 DNA Load Predict Mortality in Acinetobacter baumannii Bacteremia: Implication for Pathogenesis and Evaluation of Therapy

BACKGROUND: While quantification of viral loads has been successfully employed in clinical medicine and has provided valuable insights and useful markers for several viral diseases, the potential of measuring bacterial DNA load to predict outcome or monitor therapeutic responses remains largely unexplored. We tested this possibility by investigating bacterial loads in Acinetobacter baumannii bacteremia, a rapidly increasing nosocomial infection characterized by high mortality, drug resistance, multiple and complicated risk factors, all of which urged the need of good markers to evaluate therapeutics. METHODS AND FINDINGS: We established a quantitative real-time PCR assay based on an A. baumannii-specific gene, Oxa-51, and conducted a prospective study to examine A. baumannii loads in 318 sequential blood samples from 51 adults patients (17 survivors, 34 nonsurvivors) with culture-proven A. baumannii bacteremia in the intensive care units. Oxa-51 DNA loads were significantly higher in the nonsurvivors than survivors on day 1, 2 and 3 (P=0.03, 0.001 and 0.006, respectively). Compared with survivors, nonsurvivors had higher maximum Oxa-51 DNA load and a trend of increase from day 0 to day 3 (P<0.001), which together with Pitt bacteremia score were independent predictors for mortality by multivariate analysis (P=0.014 and 0.016, for maximum Oxa-51 DNA and change of Oxa-51 DNA, respectively). Kaplan-Meier analysis revealed significantly different survival curves in patients with different maximum Oxa-51 DNA and change of Oxa-51 DNA from day 0 to day 3. CONCLUSIONS: High Oxa-51 DNA load and its initial increase could predict mortality. Moreover, monitoring Oxa-51 DNA load in blood may provide direct parameters for evaluating new regimens against A. baumannii in future clinical studies

Solar Heating in Taiwan

AbstractSolar water heaters (SWHs) can provide hot water at temperatures ranging from 40 to 80oC for domestic or industrial use. With the subsidy programs (1986-1991 and 2000-present) offered by the Bureau of Energy, Ministry of Economic Affairs and some municipal governments, the accumulated area of solar collectors installed at the end of 2012 reached 2.25 million square meters. The well-orchestrated and concerted efforts put forward by the government of Taiwan, particularly with the Renewable Energy Development Bill promulgated in 2010, have played a significant role in the increased dissemination of SWHs. Further, the long-duration national subsidy programs might constitute one of the main driving forces for local market expansion. The mass media should be more aggressively utilized to enhance public awareness and promote utilization of SWHs. Organizations also need to consider the interests of society by being accountable for their businesses practices and by being responsible for the impact of their activities on the environment. This paper reports the current status and perspectives of SWHs in Taiwan, according to the desk and field surveys

Strategically examining the full-genome of dengue virus type 3 in clinical isolates reveals its mutation spectra

BACKGROUND: Previous studies presented the quasispecies spectrum of the envelope region of dengue virus type 3 (DENV-3) from either clinical specimens or field-caught mosquitoes. However, the extent of sequence variation among full genomic sequences of DENV within infected individuals remains largely unknown. RESULTS: Instead of arbitrarily choosing one genomic region in this study, the full genomic consensus sequences of six DENV-3 isolates were used to locate four genomic regions that had a higher potential of sequence heterogeneity at capsid-premembrane (C-prM), envelope (E), nonstructural protein 3 (NS3), and NS5. The extentof sequence heterogeneity revealed by clonal sequencing was genomic region-dependent, whereas the NS3 and NS5 had lower sequence heterogeneity than C-prM and E. Interestingly, the Phylogenetic Analysis by Maximum Likelihood program (PAML) analysis supported that the domain III of E region, the most heterogeneous region analyzed, was under the influence of positive selection. CONCLUSION: This study confirmed previous reports that the most heterogeneous region of the dengue viral genome resided at the envelope region, of which the domain III was under positive selection pressure. Further studies will need to address the influence of these mutations on the overall fitness in different hosts (i.e., mosquito and human) during dengue viral transmission

Characterization of AlInN layer grown on GaN/Sapphire substrate by MOCVD

The AlInN layers have been grown with different growth parameters on GaN/sapphire substrates by metal-organic chemical vapor deposition (MOCVD). The effects of growth parameters such as pressure and temperature on the Al incorporation during AlInN material growth have been investigated. The results showed that lower pressure provides a tendency for higher Al incorporating in the AlInN layer. Besides, as the temperature was increased from 700°C to 780°C, an estimation of 4% reduction on the indium composition has been observed for each 20°C increment. XRD analysis showed that the best crystal quality of AlInN occured at 80% Al composition because of the higher lattice matching with GaN. Based on the above criteria, an Al0.8In0.2N/GaN HEMT device with 2 μm gate length has also been fabricated. The DC characteristics showed a saturated current, Idss of 280 mA/mm and transconductance of 140 mS/mm

Induced pluripotent stem cells and regenerative medicine

AbstractStem cells, a special subset of cells derived from embryo or adult tissues, are known to present the characteristics of self-renewal, multiple lineages of differentiation, high plastic capability, and long-term maintenance. Recent reports have further suggested that neural stem cells (NSCs) derived from the adult hippocampal and subventricular regions possess the utilizing potential to develop the transplantation strategies and to screen the candidate agents for neurogenesis, neuroprotection, and neuroplasticity in neurodegenerative diseases. In this article, we review the roles of NSCs and other stem cells in neuroprotective and neurorestorative therapies for neurological and psychiatric diseases. We show the evidences that NSCs play the key roles involved in the pathogenesis of several neurodegenerative disorders, including depression, stroke, and Parkinson’s disease. Moreover, the potential and possible utilities of induced pluripotent stem cells, reprogramming from adult fibroblasts with ectopic expression of four embryonic genes, are also reviewed and further discussed. An understanding of the biophysiology of stem cells could help us elucidate the pathogenicity and develop new treatments for neurodegenerative disorders. In contrast to cell transplantation therapies, the application of stem cells can further provide a platform for drug discovery and small molecular testing, including Chinese herbal medicines. In addition, the high-throughput stem cell-based systems can be used to elucidate the mechanisms of neuroprotective candidates in translation medical research for neurodegenerative diseases

Dissemination of solar water heaters in South Africa

Global concern over a looming energy crisis, water scarcity and man-made climate change are driving a huge demand for clean technologies, which focus on preserving the earth’s resources. In South Africa, the economy is very energy-intensive with coal being the main national energy supply. In view of the growing depletion of fossil fuel, it is important for South Africa to adopt a more sustainable energy mix. This study examines the potential for widespread dissemination of solar water heaters (SWHs) in South Africa. Barriers and constraints to market expansion are analyzed to determine strategies for overcoming these barriers. It is found that payback period of a SWH is shorter than the life-span of the system itself, indicating that SWHs are economically viable even with low production cost of electricity and thus represent a profitable investment proposition for end users, manufacturers and distributors. However, the subsidy programs offered by the government of South Africa may not be sufficient to facilitate diffusion. This is attributed to the high initial capital cost of the system and low affordability of the majority of the South Africa population with low income. Alternative financing mechanisms are required