Improvement of the high-temperature oxidation resistance of Zr alloy cladding by surface modification with aluminium-containing ternary carbide coatings

Alumina-forming MAX phase ternary carbides are being considered as protective coatings on zirconium alloys as occident tolerant fuel (ATF) cladding because of their resistivity against high-temperature steam oxidation during occident scenarios. This study attempted to synthesize three types of Al-containing MAX phase carbides (Ti2AlC, Cr2AlC and Zr2AlC) as coatings on Zircaloy-4 substrates via deposition of elemental nanoscale multilayer thin films using magnetron sputtering, and subsequent thermal annealing in argon. Formation of Ti2AlC and Cr2AlC MAX hases was confirmed after annealing at 800°C and 550°C, respectively, while growth of Zr(Al)C carbide rather than Zr2AlC AX phase was observed in the Zr-C-Al system. Oxidation of the three coated samples at 1000°C in steam for 1 hour evealed no protective effect of the Ti2AlC and Zr(Al)C coatings with significant spallation and cracking. The Cr2AlC oatings possess superior oxidation resistance and self-healing capability with a thin and dense α-Al2O3 layer growth on the surface, which shows good promise as a candidate for coated ATF claddings

Mitochondrial precursor proteins are imported through a hydrophilic membrane environment

We have analyzed how translocation intermediates of imported mitochondrial precursor proteins, which span contact sites, interact with the mitochondrial membranes. F1-ATPase subunit β(F1β) was trapped at contact sites by importing it into Neurospora mitochondria in the presence of low levels of nucleoside triphosphates. This F1β translocation intermediate could be extracted from the membranes by treatment with protein denaturants such as alkaline pH or urea. By performing import at low temperatures, the ADP/ATP carrier was accumulated in contact sites of Neurospora mitochondria and cytochrome b2 in contact sites of yeast mitochondria. These translocation intermediates were also extractable from the membranes at alkaline pH. Thus, translocation of precursor proteins across mitochondrial membranes seems to occur through an environment which is accessible to aqueous perturbants. We propose that proteinaceous structures are essential components of a translocation apparatus present in contact sites

Substrate finishing and niobium content effects on the high temperature corrosion resistance in steam atmosphere of CrN/NbN superlattice coatings deposited by PVD-HIPIMS

The main objective of this work was to evaluate the oxidation resistance of three PVD-HIPIMS CrN/NbN coatings, studying the effect of the surface finishing of the substrate and the role of niobium content into the coating composition. CrN/NbN nano-multilayered films on P92 steel were tested at 650°C in pure steam atmosphere. The mass gain was measured at fixed intervals to study their oxidation kinetics. The morphology and thickness of nanoscales were measured by transmission electron microscopy (TEM). Characterization of coatings before and after the thermal treatment was performed by scanning electron microscopy-energy with facilities of dispersive X-ray spectroscopy (SEM–EDX) and X-ray diffraction (XRD). All coatings improved the oxidation resistance of the substrate material, but the best behaviour was exhibited by the CrN/NbN with the high niobium (Nb) content and deposited on the substrate with the finest surface finishing

Polymorphisms of glutathione S-transferases (GST) and thymidylate synthase (TS) – novel predictors for response and survival in gastric cancer patients

To evaluate the predictive value of a panel of gene polymorphisms involved in metabolism of 5-FU and cisplatin on clinical outcome in advanced gastric cancer patients. A total of 52 patients were enrolled in this study. DNA was extracted from paraffin-embedded tumour specimen. Genotypes were determined using PCR-RFLP. Median survival time was 6.0 months (95% CI 3.9;8.1). Overall response rate was 26%. Patients possessing the glutathione S-transferase P1-105 Valine/Valine (GSTP1-105VV) genotype showed a response rate of 67% compared to 21% in patients harbouring at least one GSTP1-105 Isoleucine (GSTP1-105I) allele (P=0.038). GSTP1-105VV patients demonstrated a significant superior median survival time of 15.0 months (95% CI 7.8;22.0) compared to 6.0 months (95% CI 5.1;7.0) in patients with at least one GSTP1-105I allele (P=0.037). Patients possessing a favourable thymidylate synthase (TS) genotype (2R/2R, 2R/3RC, 3RC/3RC) experienced a superior survival time of 10.2 months (95% CI 5.1;15.3) compared to 6.0 months (95% CI 5.0;7.0) in patients with unfavourable TS genotypes (P=0.099). Patients harbouring the GSTP1-105II genotype and one of the unfavourable TS genotypes showed an inferior median survival time of 6.0 months (95% CI 3.9;8.1) compared to 11 months (95% CI 6,23;15,77) in patients with either GSTP1-105VV or a favourable TS genotype (P=0.044). Testing for TS and GSTP1 polymorphisms may allow identification of gastric cancer patients who will benefit from 5-FU/cisplatin chemotherapy, sparing others the side effects of this chemotherapy

Effects of a recombinant gene expression on ColE1-like plasmid segregation in Escherichia coli

<p>Abstract</p> <p>Background</p> <p>Segregation of expression plasmids leads to loss of recombinant DNA from transformed bacterial cells due to the irregular distribution of plasmids between the daughter cells during cell division. Under non-selective conditions this segregational instability results in a heterogeneous population of cells, where the non-productive plasmid-free cells overgrow the plasmid-bearing cells thus decreasing the yield of recombinant protein. Amongst the factors affecting segregational plasmid instability are: the plasmid design, plasmid copy-number, host cell genotype, fermentation conditions etc. This study aims to investigate the influence of transcription and translation on the segregation of recombinant plasmids designed for constitutive gene expression in <it>Escherichia coli </it>LE392 at glucose-limited continuous cultivation. To this end a series of pBR322-based plasmids carrying a synthetic human interferon-gamma (hIFNγ) gene placed under the control of different regulatory elements (promoter and ribosome-binding sites) were used as a model.</p> <p>Results</p> <p>Bacterial growth and product formation kinetics of transformed <it>E. coli </it>LE392 cells cultivated continuously were described by a structured kinetic model proposed by Lee et al. (1985). The obtained results demonstrated that both transcription and translation efficiency strongly affected plasmid segregation. The segregation of plasmid having a deleted promoter did not exceed 5% after 190 h of cultivation. The observed high plasmid stability was not related with an increase in the plasmid copy-number. A reverse correlation between the yield of recombinant protein (as modulated by using different ribosome binding sites) and segregational plasmid stability (determined by the above model) was also observed.</p> <p>Conclusions</p> <p>Switching-off transcription of the hIFNγ gene has a stabilising effect on ColE1-like plasmids against segregation, which is not associated with an increase in the plasmid copy-number. The increased constitutive gene expression has a negative effect on segregational plasmid stability. A kinetic model proposed by Lee et al. (1985) was appropriate for description of <it>E. coli </it>cell growth and recombinant product formation in chemostat cultivations.</p

Uncertainty and Narratives of the Future. A Theoretical Framework for Contemporary Fertility

Explanations for fertility decisions based on structural constraints—such as labor, housing condition, or income—do not account for the contemporary fertility downturn faced by many countries in Europe. In this paper, we posit that the rise of uncertainty is central for understanding contemporary fertility dynamics. We propose a theoretical framework (the Narrative Framework) for the study of fertility decisions under uncertain conditions based on expectations, imaginaries and narratives. Relying on the idea of future–oriented action, we argue that uncertainty needs to be conceptualized and operationalized taking into account that people use works of imagination, producing their own narrative of the future. Narratives of the future are potent driving forces helping people to act according to or despite uncertainty. We present the different elements of the Narrative Framework and address its causal validity. We conclude by highlighting the advantages of taking into account the narratives of the future in fertility research