New Understandings of Ethanol Oxidation Reaction Mechanism on Pd/C and Pd2Ru/C Catalysts in Alkaline Direct Ethanol Fuel Cells

Ethanol oxidation reaction (EOR) on Pd2Ru/C and Pd/C catalysts in alkaline media is studied comprehensively by cyclic voltammetry, chronoamperometry, in situ FTIR, single fuel cell test and electrochemical impedance spectroscopy measurements. The results show that, as compared to Pd/C, Pd2Ru/C favors acetaldehyde formation and hinders its oxidation. Based on X-ray absorption data, which evidence that Ru promotes a larger electronic vacancy of the Pd 4d band, it is expected that the formation of adsorbed ethoxy is favored on Pd2Ru/C and followed by its oxidation to acetaldehyde facilitated by oxygenated species provided by Ru. In contrast, acetaldehyde oxidation is more difficult on Pd2Ru/C than on Pd/C likely because the adsorption energy of the reactive species is increased. We also show that the performance of Pd2Ru/C anode in alkaline direct ethanol fuel cell (ADEFC) is initially better but degrades much more rapidly than that with Pd/C anode under the same test conditions. The degradation is demonstrated to result from the accumulation of large amounts of acetaldehyde, which in alkaline media forms dimers by the aldol condensation reaction. The dimers tend to be responsible for blocking the active sites for further ethanol oxidation. This comprehensive study provides new understandings of the roles of Ru in Pd2Ru/C for EOR in alkaline media, unveils the causes of the performance degradation of fuel cells with Pd2Ru/C and demonstrates that initial good performances are not necessarily a valid criterion for selecting appropriate anode catalysts for ADEFC applications

MicroRNA-200c overexpression inhibits tumorigenicity and metastasis of CD117+CD44+ ovarian cancer stem cells by regulating epithelial-mesenchymal transition

BACKGROUND: Cancer stem cells (CSCs) are believed to be ‘seed cell’ in cancer recurrence and metastasis. MicroRNAs (miRNAs) can play an important role in the progression of primary tumor towards metastasis by regulating the epithelial-mesenchymal transition (EMT). The goal of this study was to investigate the effect of miRNA-200c overexpression on the EMT, tumorigenicity and metastasis of epithelial ovarian cancer (EOC) CSCs. METHODS: The EOC CD117(+)CD44(+)CSCs were isolated from the human ovarian cancer cell line SKOV3 by using a magnetic-activated cell sorting system, and the lentivirus miR-200c transduced CSCs were then selected for the study. The assays of colony forming, wound healing, cellular migration in vitro and tumor progression in vivo were performed. RESULTS: The miR-200c expression was reduced in the CD117(+)CD44(+)CSCs compared with the non-CD117(+)CD44(+)CSCs. However, the stable overexpression of the miR-200c in the CD117(+)CD44(+)CSCs resulted in a significant down-regulation of ZEB-1 and the Vimentin expression, an upregulation of the E-cadherin expression as well as a decrease of colony forming, migratory and invasion in vitro. Importantly, the miR-200c overexpression significantly inhibited the CD117(+)CD44(+)CSCs xenograft growth and lung metastasis in vivo in nude mice by inhibition of the EMT. In addition, the down-regulation of ZEB-1 showed the same efficacy as the miR-200c overexpression in the CD117(+)CD44(+)CSCs. CONCLUSION: These findings from this study suggest that the miR-200c overexpression may be considered a critical approach for the EOC CD117(+)CD44(+)CSCs in clinical trials

Engineering Escherichia coli for autoinducible production of n-butanol

Background: Escherichia coli does not produce n-butanol naturally, but can be butanologenic when related enzymes were expressed using inducible elements on plasmids. In this study we attempted to confer E. coli strain capability of automatic excretion of the chemical by employing a native anaerobic promoter. Also, a novel DNA kit was designed for PCR preparation of linear DNA fragments to perform strain modification. The kit is primarily composed of two mother vectors, co-transformation of linear DNAs into E. coli can simultaneously introduce two butanol synthetic operons into the chromosome and create two in-frame gene deletions at targeted native loci. Results: E. coli strain Bw2V carries plasmid pCNA-PHC and pENA-TA, both utilizes native anaerobic promoter Phya for the expression of butanol synthetic enzymes. When Bw2V was subjected in anaerobic fermentation using medium containing extra glucose, the accumulated n-butanol in the broth was up to 2.8 g/L in bioreactor; as the genetic element expressing the same pathway was introduced into the genome, the titer of butanol was 1.4 g/L. Conclusions: The expression systemusing Phya is effective in applications that involve expression plasmids as also applicable in ectopic expression as single copy on the chromosome. Results imply that Phya can be subjected for broader application in bioproduction of more feedstock chemicals

Improved Biogeography-Based Optimization approach to secondary protein prediction

In recent years, many bio-inspired computation algorithms have been proposed to solve constraint problems. Biogeography-Based Optimization (BBO) is one of these newly proposed optimization algorithms. As a new way to solve complicated optimization problems, BBO has a quick convergence. In this paper, we proposed an improved BBO for solving protein structure prediction problems. Comparative experiments with standard BBO and differential evolution algorithm (DE) are also conducted, and the results demonstrate this improved BBO approach performs better in solving these complicated protein prediction problems. ? 2014 IEEE.EI4223-422

A moving target extraction algorithm based on the fusion of infrared and visible images

According to the principle of thermal imaging, moving targets can be better located in infrared images, but their boundary is blurred, and the details of objects cannot be displayed. The details of objects in natural images can be better shown, but for the condition of shelter, shadow and etc., miss-tracking and false-tracking may easily occur. Thus, we construct a framework for moving target extraction and tracking in infrared and natural images. For infrared images: according to the rough fuzzy set theory, we propose the rough entropy model based on the traditional frame difference method. The model is fused with the infrared imaging characteristics to locate moving target regions. For natural images: a time-space fusion LBP model is proposed for target coding. The model is integrated into the GMM model to obtain moving target information. The moving regions in infrared images and natural images are fused to form a priori model, and the C-V model is improved to extract targets accurately

Synthesis of Glycolate by Bacillus subtilis through Glyoxylate Bypass Pathway

In order to construct a food-safe strain that could produce glycolate, the metabolic modification of Bacillus subtilis was carried out. In this study, the exogenous isocitrate lyase gene (aceA) was first integrated into the genome of Bacillus subtilis by homologous recombination, and the starting strain 164MCT-GA was constructed. Then the glycolate anabolism was optimized by means of metabolic engineering in the starting strain 164MCT-GA. The results showed that 164MCT-GA could synthesize glycolate with glycerol as substrate, and the yield of shaker fermentation was 0.114 g/L. To increase the supply of the key intermediate substrates, the citrate synthase gene (citA) and the glyoxylate reductase gene (yvcT) were overexpressed by replacing the native promoter with individual T7 promoter. The Bacillus strains were further engineered at multiple loci that included lactate dehydrogenase (ldh), phosphate acetyltransferase (pta) and acetyl-CoA transacetylase (mmgA, yhfs), in an attempt to modulate the carbon flux toward the formation of glycolate with a higher efficiency. The fermentation study revealed that the accumulated concentration of glycolate from the obtained B. subtilis strain GA3-52 reached 0.572 g/L, with a conversion rate of 0.175 g/g glycerol, the titer was more than five times as much as that achieved by 164MCT-GA. Thus, this study constructed a de novo synthesis pathway in B. subtilis, and laid the foundation for the fermentation production of high yield glycolic acid by food safety bacteria

Engineering Escherichia coli for autoinducible production of n-butanol

Background: Escherichia coli does not produce n-butanol naturally, but can be butanologenic when related enzymes were expressed using inducible elements on plasmids. In this study we attempted to confer E. coli strain capability of automatic excretion of the chemical by employing a native anaerobic promoter. Also, a novel DNA kit was designed for PCR preparation of linear DNA fragments to perform strain modification. The kit is primarily composed of two mother vectors, co-transformation of linear DNAs into E. coli can simultaneously introduce two butanol synthetic operons into the chromosome and create two in-frame gene deletions at targeted native loci. Results: E. coli strain Bw2V carries plasmid pCNA-PHC and pENA-TA, both utilizes native anaerobic promoter Phya for the expression of butanol synthetic enzymes. When Bw2V was subjected in anaerobic fermentation using medium containing extra glucose, the accumulated n-butanol in the broth was up to 2.8 g/L in bioreactor; as the genetic element expressing the same pathway was introduced into the genome, the titer of butanol was 1.4 g/L. Conclusions: The expression system using Phya is effective in applications that involve expression plasmids as also applicable in ectopic expression as single copy on the chromosome. Results imply that Phya can be subjected for broader application in bioproduction of more feedstock chemicals

Simultaneous chromatographic fingerprinting and quantitative analysis of flavonoids in Pollen Typhae by high-performance capillary electrophoresis

To evaluate the quality of Pollen Typhae as used in traditional Chinese medicine, a high-performance capillary electrophoresis (HPCE) method has been developed, validated and applied to chromatographic fingerprinting and quantitation of its eight main bioactive flavonoids (naringenin, isorhamnetin 3-O-(2G-α-l-rhamnosyl)-rutinoside, rhamnetin 3-O-neohesperidoside, isorhamnetin, quercetin 3-O-(2G-α-l-rhamnosyl)-rutinoside, quercetin 3-O-neohesperidoside, kaempferol and quercetin). Fingerprinting was based on the selection of nine characteristic chromatographic peaks. In quantitative analysis, the recovery of all eight compounds was in the range 98.5–102.2% with good linearity (r2>0.9919) over a relatively wide concentration range. The assay was successfully applied to the analysis of the eight bioactive flavonoids in 14 different samples. The results indicate that the assay is reproducible and precise and can be used for convenient quality assessment of Pollen Typhae

Combination of multiple strengthening mechanisms facilitates excellent strength-ductility balance in metastable β titanium alloy

A remarkable balance between the strength (844 MPa) and ductility (35.6%) of the Ti–4V–2Mo–2Fe alloy was achieved by hot rolling. Notably, alloy specimens rolled at 700 °C exhibited a yield strength exceeding 1 GPa. This outstanding yield strength from several factors: fine-grain strengthening, dislocations strengthening in the non-recrystallized region, and precipitation strengthening of α phase and isothermal ω phase. Within the 750–900 °C temperature range, a notable enhancement in yield strength, uniform elongation, total elongation, and work hardening rate was observed as rolling temperature decreased. This enhancement can be attributed to the “dynamic Hall-Petch effect” caused by the stress-induced {332} twins. Additionally, grain refinement and stress-induced ω phase further enhanced ductility and work hardening capacity. These findings show that reasonable adjustment of microstructure and deformation mechanism is an effective strategy to achieve excellent strength-ductility balance of metastable β titanium alloys