The formation of intermetallic compounds (IMCs) during the friction stir welding (FSW) of aluminum and steel is problematic because these IMCs can reduce weld strength. In this study, the mechanism ...behind the observed rapid growth of IMCs during the dissimilar FSW of aluminum and steel was investigated. The temperature during welding was measured using
K
-type thermocouples, and the microstructures of cross sections of the welded materials were examined via scanning electron microscopy. Microstructural observations indicated that the growth of IMCs was not constant, but occurred in two rapid growth steps. The first phase of rapid IMC growth was observed immediately after the probe contacted the steel, while the second began in the region subjected to the large downward pressure of the tool shoulder on the steel plate. The measurements showed that the temperature underneath the tool shoulder was higher than that at the tool probe. Additionally, it was found that the two IMC growth steps and the growth rate could be expressed by an equation based on metallic diffusion and the measured temperatures. As the IMCs grew rapidly via contact between the steel plate and the tool probe or shoulder, it is necessary to control such contacts to inhibit IMC growth. This strategy and the proposed formula for predicting IMC growth rates could help improve the strength of welds during the fabrication of lightweight materials in the automotive and aerospace industries.
•Metabolically engineered Escherichia coli is treated as a microbial chassis.•Pathway engineering to generate E. coli chassis is summarized.•Strategies for accumulating 5 important metabolic ...intermediates are highlighted.
The present work reviews literature describing the re-design of the metabolic pathways of a microbial host using sophisticated genetic tools, yielding strains for producing value-added chemicals including fuels, building-block chemicals, pharmaceuticals, and derivatives. This work employed Escherichia coli, a well-studied microorganism that has been successfully engineered to produce various chemicals. E. coli has several advantages compared with other microorganisms, including robustness, and handling. To achieve efficient productivities of target compounds, an engineered E. coli should accumulate metabolic precursors of target compounds. Multiple researchers have reported the use of pathway engineering to generate strains capable of accumulating various metabolic precursors, including pyruvate, acetyl-CoA, malonyl-CoA, mevalonate and shikimate. The aim of this review provides a promising guideline for designing E. coli strains capable of producing a variety of useful chemicals. Herein, the present work reviews their common and unique strategies, treating metabolically engineered E. coli as a “microbial chassis”.
In order to decrease carbon emissions and negative environmental impacts of various pollutants, biofuel/biochemical production should be promoted for replacing fossil-based industrial processes. ...Utilization of abundant lignocellulosic biomass as a feedstock has recently become an attractive option. In this review, we focus on recent efforts of cell surface display using industrial microorganisms such as Escherichia coli and yeast. Cell surface display is used primarily for endowing cellulolytic activity on the host cells, and enables direct fermentation to generate useful fuels and chemicals from lignocellulosic biomass. Cell surface display systems are systematically summarized, and the drawbacks/perspectives as well as successful application of surface display for industrial biotechnology are discussed.
The balance between cell death and survival is a critical parameter in the regulation of cells and the maintenance of homeostasis in vivo. Three major mechanisms for cell death have been identified ...in mammalian cells: apoptosis (type I), autophagic cell death (type II), and necrosis (type III). These three mechanisms have been suggested to engage in cross talk with each other. Among them, autophagy was originally characterized as a cell survival mechanism for amino acid recycling during starvation. Whether autophagy functions primarily in cell survival or cell death is a critical question yet to be answered. Here, we present a comprehensive review of the cell death-related events that take place during autophagy and their underlying mechanisms in cancer and autoimmune disease development.
Post-weld properties of dissimilar friction stir welds of mild steel/A7075-T6 aluminum alloy were investigated. The joint strength increased with reduction in thickness of the intermetallic compound ...at the weld interface. During tensile tests of the composite weld, no weld failed in the aluminum base metal. Comprehensive analysis using the heat input parameter showed that the apparent interface strength between the steel and aluminum was lower than the joint strength of the friction-stir-welded A7075-T6 alloy.
Glucose and xylose are the major components of lignocellulose. Effective utilization of both sugars can improve the efficiency of bioproduction. Here, we report a method termed parallel metabolic ...pathway engineering (PMPE) for producing shikimate pathway derivatives from glucose-xylose co-substrate. In this method, we seek to use glucose mainly for target chemical production, and xylose for supplying essential metabolites for cell growth. Glycolysis and the pentose phosphate pathway are completely separated from the tricarboxylic acid (TCA) cycle. To recover cell growth, we introduce a xylose catabolic pathway that directly flows into the TCA cycle. As a result, we can produce 4.09 g L
cis,cis-muconic acid using the PMPE Escherichia coli strain with high yield (0.31 g g
of glucose) and produce L-tyrosine with 64% of the theoretical yield. The PMPE strategy can contribute to the development of clean processes for producing various valuable chemicals from lignocellulosic resources.
Background
Several studies have investigated the diagnostic accuracy of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for pancreatic lesions, but they have included only limited ...patient populations. This study aimed to clarify the diagnostic accuracy of EUS-FNA in a large number of pancreatic lesions, and to describe the factors that influence it.
Methods
From March 1997 to May 2010, 944 consecutive patients who had undergone EUS-FNA for pancreatic solid lesions were evaluated retrospectively. Factors affecting EUS-FNA accuracy were then analyzed.
Results
A total of 996 solid pancreatic lesions were sampled by EUS-FNA. The overall sampling adequacy and diagnostic accuracy of these lesions were 99.3 % (989/996) and 91.8 % (918/996), respectively. The sensitivity and specificity for differentiating malignant from benign lesions were 91.5 % (793/867) and 97.7 % (126/129), respectively. The diagnostic performance was significantly higher when both cytological and cell-block examinations were carried out than with only cytological examination. In multivariate analysis, final diagnosis, location of lesion, lesion size, availability of on-site cytopathological evaluation, and experience of EUS-FNA procedure were independent factors affecting the accuracy of EUS-FNA. On-site cytopathological evaluation and lesion size were found to be the most weighted factors affecting diagnostic accuracy.
Conclusions
EUS-FNA for pancreatic solid lesions yielded a high accuracy and low complication rate. Both cytological and cell-block preparations and on-site cytopathological evaluation contributed to improve the accuracy. The diagnostic ability of EUS-FNA was less for smaller lesions, and repeated procedures may be needed if malignancy is suspected.
infection is a well-known risk factor for gastric cancer. However, the contribution of germline pathogenic variants in cancer-predisposing genes and their effect, when combined with
infection, on the ...risk of gastric cancer has not been widely evaluated.
We evaluated the association between germline pathogenic variants in 27 cancer-predisposing genes and the risk of gastric cancer in a sample of 10,426 patients with gastric cancer and 38,153 controls from BioBank Japan. We also assessed the combined effect of pathogenic variants and
infection status on the risk of gastric cancer and calculated the cumulative risk in 1433 patients with gastric cancer and 5997 controls from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC).
Germline pathogenic variants in nine genes (
,
,
,
,
,
,
,
, and
) were associated with the risk of gastric cancer. We found an interaction between
infection and pathogenic variants in homologous-recombination genes with respect to the risk of gastric cancer in the sample from HERPACC (relative excess risk due to the interaction, 16.01; 95% confidence interval CI, 2.22 to 29.81; P = 0.02). At 85 years of age, persons with
infection and a pathogenic variant had a higher cumulative risk of gastric cancer than noncarriers infected with
(45.5% 95% CI, 20.7 to 62.6 vs. 14.4% 95% CI, 12.2 to 16.6).
infection modified the risk of gastric cancer associated with germline pathogenic variants in homologous-recombination genes. (Funded by the Japan Agency for Medical Research and Development and others.).
This study focused on the process development for the d-lactic acid production from cellulosic feedstocks using the Lactobacillus plantarum mutant, genetically modified to produce optically pure ...d-lactic acid from both glucose and xylose. The simultaneous saccharification and fermentation (SSF) using delignified hardwood pulp (5-15% loads) resulted in the lactic acid titers of 55.2-84.6g/L after 72h and increased productivities of 1.77-2.61g/L/h. To facilitate the enzymatic saccharification of high-load pulp at a fermentation temperature, short-term (⩽10min) pulverization of pulp was conducted, leading to a significantly improved saccharification with the suppressed formation of formic acid by-product. The short-term milling followed by SSF resulted in a lactic acid titer of 102.3g/L, an optical purity of 99.2%, and a yield of 0.879g/g-sugars without fed-batch process control. Therefore, the process presented here shows promise for the production of high-titer d-lactic acid using the L. plantarum mutant.
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