Enhancement of Transition Temperature in FexSe0.5Te0.5 Film via Iron Vacancies

The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8<x<1) on superconductivity and electronic properties have been studied. A significant enhancement of the superconducting transition temperature (TC) up to 21K was observed in the most Fe deficient film (x=0.8). Based on the observed and simulated structural variation results, there is a high possibility that Fe vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows a strong relationship with the lattice strain effect induced by Fe vacancies. Importantly, the presence of Fe vacancies alters the charge carrier population by introducing electron charge carriers, with the Fe deficient film showing more metallic behavior than the defect-free film. Our study provides a means to enhance the superconductivity and tune the charge carriers via Fe vacancy, with no reliance on chemical doping.Comment: 15 pages, 4 figure

Shadow replication: An energy-aware, fault-tolerant computational model for green cloud computing

As the demand for cloud computing continues to increase, cloud service providers face the daunting challenge to meet the negotiated SLA agreement, in terms of reliability and timely performance, while achieving cost-effectiveness. This challenge is increasingly compounded by the increasing likelihood of failure in large-scale clouds and the rising impact of energy consumption and CO2 emission on the environment. This paper proposes Shadow Replication, a novel fault-tolerance model for cloud computing, which seamlessly addresses failure at scale, while minimizing energy consumption and reducing its impact on the environment. The basic tenet of the model is to associate a suite of shadow processes to execute concurrently with the main process, but initially at a much reduced execution speed, to overcome failures as they occur. Two computationally-feasible schemes are proposed to achieve Shadow Replication. A performance evaluation framework is developed to analyze these schemes and compare their performance to traditional replication-based fault tolerance methods, focusing on the inherent tradeoff between fault tolerance, the specified SLA and profit maximization. The results show that Shadow Replication leads to significant energy reduction, and is better suited for compute-intensive execution models, where up to 30% more profit increase can be achieved due to reduced energy consumption

Microbial diversity in a full-scale anaerobic reactor treating high concentration organic cassava wastewater

Microbial characteristics in the up-flow anaerobic sludge blanket reactor (UASB) of a full-scale high concentration cassava alcohol wastewater plant capable of anaerobic hydrocarbon removal were analyzed using cultivation-independent molecular methods. Forty-five bacterial operational taxonomic units (OTUs) and 24 archaeal OTUs were identified by building 16S rRNA gene of bacterial and archaeal clone libraries. Most bacterial OTUs were identified as phyla of Firmicutes (53.3%), Chloroflexi (20.0%), Proteobacteria (11.1%), Bacteroidetes (6.7%) and a candidate division (2.2%). Methanosaeta (57.5%) were the most abundant archaeal group, followed by Methanobacterium (10.6%), Methanomethylovorans (8.5%) and Methanosarcina (6.4%). Most bacterial species take charge of cellulolysis, proteolysis, acidogenesis and homo-acetogenesis; the most methanogens were typical hydrogenotrophic or hydrogenotrophic/aceticlastic. This study revealed a succession of both bacterial and archaeal populations during the trial, which could be linked to operational adaptation of high concentration organic cassava wastewater.Keywords: Full-scale, anaerobic reactor, 16S rRNA gene clone library, microbial diversity, functional analysis