Microbiologically induced corrosion of 70Cu-30Ni alloy in anaerobic seawater

The corrosion of 70Cu-30Ni alloy induced by sulfate-reducing bacteria (SRB) in seawater was investigated by microscopic and electrochemical methods. Under anaerobic conditions, the SRB attached on the alloy surface formed blotchy biofilms, as observed by confocal laser scanning microscopy. Intergranular corrosion of the alloy occurred after immersion in SRB-containing seawater for 7 days, as observed by atomic force and scanning electron microscopy. Compared to the control experiment in the absence of SRB, a 330 mV shift of open-circuit potential resulted in the active direction and the polarization resistance decreased by a factor of 10. Electrochemical impedance spectroscopy data revealed that the impedance had remarkable capacitive characteristics. The response of the impedance was determined by two time constants for both the media with and without SRB. Analyses of concentrations of bacteria, metabolites, Cu, and Ni showed that the variation of concentrations of metabolites coincided with the growth of bacteria, and copper and nickel precipitated due to the production of metal sulfide, The effect of bacteria growth was the precipitation of cuprous sulfide to lower the potential of the anodic reaction and the reduction of hydrogen sulfide as the possible cathodic reaction. © 2004 The Electrochemical Society. All rights reserved.published_or_final_versio

Atomic Force Microscopy Study of Microbiologically Influenced Corrosion of Mild Steel

The anaerobic corrosion of mild steel in seawater was studied by atomic force microscopy (AFM). In the presence of sulfate reducing bacteria (SRB), corrosion was intensified and accelerated. A biofilm consists of heterogeneous microbial cells and extracellular polymeric substance with interstitial voids was observed on the surface of mild steel coupons. The greatest damage of steel occurred beneath the biofilm, in the form of pitting corrosion. The corrosion of steel can be quantified through section and bearing analyses. The depth of pits increased linearly with time whereas the volume of pits increased as f2.83, the 2.83 power of time. Compared with a control experiment without SRB, the depth of pitting corrosion is about one order of magnitude higher. Weight loss estimates from AFM images are about one order of magnitude smaller than actual weight loss experimental results. The problems of AFM quantification of corrosion rate al extended stage of corrosion are discussed. © 1999 The Electrochemical Society. S0013-4651(99)01-006-X. All rights reserved.published_or_final_versio

High Methanol Oxidation Activity of Well-Dispersed Pt Nanoparticles on Carbon Nanotubes Using Nitrogen Doping

Pt nanoparticles (NPs) with the average size of 3.14 nm well dispersed on N-doped carbon nanotubes (CNTs) without any pretreatment have been demonstrated. Structural properties show the characteristic N bonding within CNTs, which provide the good support for uniform distribution of Pt NPs. In electrochemical characteristics, N-doped CNTs covered with Pt NPs show superior current density due to the fact that the so-called N incorporation could give rise to the formation of preferential sites within CNTs accompanied by the low interfacial energy for immobilizing Pt NPs. Therefore, the substantially enhanced methanol oxidation activity performed by N-incorporation technique is highly promising in energy-generation applications

Radial Growth of Qilian Juniper on the Northeast Tibetan Plateau and Potential Climate Associations

There is controversy regarding the limiting climatic factor for tree radial growth at the alpine treeline on the northeastern Tibetan Plateau. In this study, we collected 594 increment cores from 331 trees, grouped within four altitude belts spanning the range 3550 to 4020 m.a.s.l. on a single hillside. We have developed four equivalent ring-width chronologies and shown that there are no significant differences in their growth-climate responses during 1956 to 2011 or in their longer-term growth patterns during the period AD 1110–2011. The main climate influence on radial growth is shown to be precipitation variability. Missing ring analysis shows that tree radial growth at the uppermost treeline location is more sensitive to climate variation than that at other elevations, and poor tree radial growth is particularly linked to the occurrence of serious drought events. Hence water limitation, rather than temperature stress, plays the pivotal role in controlling the radial growth of Sabina przewalskii Kom. at the treeline in this region. This finding contradicts any generalisation that tree-ring chronologies from high-elevation treeline environments are mostly indicators of temperature changes

Decitabine impact on the endocytosis regulator RhoA, the folate carriers RFC1 and FOLR1, and the glucose transporter GLUT4 in human tumors.

BackgroundIn 31 solid tumor patients treated with the demethylating agent decitabine, we performed tumor biopsies before and after the first cycle of decitabine and used immunohistochemistry (IHC) to assess whether decitabine increased expression of various membrane transporters. Resistance to chemotherapy may arise due to promoter methylation/downregulation of expression of transporters required for drug uptake, and decitabine can reverse resistance in vitro. The endocytosis regulator RhoA, the folate carriers FOLR1 and RFC1, and the glucose transporter GLUT4 were assessed.ResultsPre-decitabine RhoA was higher in patients who had received their last therapy >3 months previously than in patients with more recent prior therapy (P = 0.02), and varied inversely with global DNA methylation as assessed by LINE1 methylation (r = -0.58, P = 0.006). Tumor RhoA scores increased with decitabine (P = 0.03), and RFC1 also increased in patients with pre-decitabine scores ≤150 (P = 0.004). Change in LINE1 methylation with decitabine did not correlate significantly with change in IHC scores for any transporter assessed. We also assessed methylation of the RFC1 gene (alias SLC19A1). SLC19A1 methylation correlated with tumor LINE1 methylation (r = 0.45, P = 0.02). There was a small (statistically insignificant) decrease in SLC19A1 methylation with decitabine, and there was a trend towards change in SLC19A1 methylation with decitabine correlating with change in LINE1 methylation (r = 0.47, P <0.15). While SLC19A1 methylation did not correlate with RFC1 scores, there was a trend towards an inverse correlation between change in SLC19A1 methylation and change in RFC1 expression (r = -0.45, P = 0.19).ConclusionsIn conclusion, after decitabine administration, there was increased expression of some (but not other) transporters that may play a role in chemotherapy uptake. Larger patient numbers will be needed to define the extent to which this increased expression is associated with changes in DNA methylation

The association between atopic eczema and lymphopenia: results from a UK cohort study with replication in US survey data.

BACKGROUND: Lymphocyte skin homing in atopic eczema (AE) may induce lymphopenia. OBJECTIVE: To determine if AE is associated with lymphopenia. METHODS: We used UK primary care electronic health records (Clinical Practice Research Datalink GOLD) for a matched cohort study in adults (18yrs+) (1997-2015) with at least 1 recorded lymphocyte count. We matched people with AE to up to 5 people without. We used multivariable logistic regression to estimate the association between AE and lymphopenia (two low lymphocyte counts within 3 months) and linear mixed effects regression to estimate the association with absolute lymphocyte counts using all available counts. Cox proportional hazard models were used to investigate the effect of lymphopenia on common infections. We replicated the study using US survey data (National Health and Nutrition Examination Survey [NHANES]). RESULTS: Amongst 71,731 adults with AE and 126,349 adults without AE, we found an adjusted odds ratio (OR) for lymphopenia of 1.16 (95%CI: 1.09-1.23), the strength of association increased with increasing eczema severity. When comparing all recorded lymphocyte counts from adults with AE(n=1,497,306) to those of people without AE(n=4,035,870) we saw a lower mean lymphocyte (adjusted mean difference -0.047*109 /L (95%CI:- 0.051- -0.043)) in those with AE. The difference was larger for men, increasing age, increasing AE severity and was present among people with AE not treated with immunosuppressive drugs. In NHANES (n=22,624), the adjusted OR for lymphopenia in adults with AE was 1.30 (95% CI 0.80-2.11), and the adjusted mean lymphocyte count difference was -0.03*109 /L (95%CI -0.07-0.02). Despite having a lower lymphocyte count, adjusting for time with lymphopenia, did not alter risk estimates of infections. CONCLUSION: AE, including increasing AE severity, is associated with a decreasing lymphocyte count, regardless of immunosuppressive drug use.. Whether the decreasing lymphocyte count has wider health implications for people with severe eczema warrants further investigation

IL-12 RB1 Genetic Variants Contribute to Human Susceptibility to Severe Acute Respiratory Syndrome Infection among Chinese

BACKGROUND: Cytokines play important roles in antiviral action. We examined whether polymorphisms of interleukin (IL)-12 receptor B1 (IL-12RB1) affect the susceptibility to and outcome of severe acute respiratory syndrome (SARS). METHODS: A case-control study was carried out in Chinese SARS patients and healthy controls. The genotypes of 4SNPs on IL-12 RB1 gene, +705A/G,+1158T/C, +1196G/C and +1664 C/T, were determined by PCR-RFLP. Haplotypes were estimated from the genotype data using the expectation-maximisation algorithm. RESULTS: Comparison between patients and close contacts showed that individuals with the +1664 C/T (CT and TT) genotype had a 2.09-fold (95% confidence interval [CI], 1.90-7.16) and 2.34-fold (95% CI, 1.79-13.37) increased risk of developing SARS, respectively. For any of the other three polymorphisms, however, no significant difference can be detected in allele or genotype frequencies between patients and controls. Additionally, estimation of the frequencies of multiple-locus haplotypes revealed potential risk haplotypes (GCCT) for SARS infection. CONCLUSIONS: Our data indicate that genetic variants of IL12RB1confer genetic susceptibility to SARS infection, but not necessary associated with the progression of the disease in Chinese population