Evaluation of Hydrogen Permeation into High-Strength Steel during Corrosion in Different Marine Corrosion Zones

Hydrogen permeation into high-strength steel during the corrosion process can deteriorate their mechanical properties, thus seriously threatening the safety of steel structures. However, the hydrogen permeation behavior of steels in corrosive marine environments is not well understood. In this study, the hydrogen permeation behavior and mechanism of AISI 4135 steel in different marine corrosion zones was investigated for the first time using an in situ hydrogen permeation monitoring system via outdoor and indoor tests. The three-month outdoor hydrogen permeation test showed that the diffusible hydrogen content of the steels exposed to the marine atmospheric, splash, tidal and immersion zone was 3.15 × 10−3, 7.00 × 10−2, 2.06 × 10−2 and 3.33 × 10−2 wt ppm, respectively. Meanwhile, results showed that the hydrogen permeation current density was positively correlated with the corrosion rate of the steel in the marine environments. This research is of great significance for guiding the safe application of high-strength steel in the marine environments

Determination of Extra- and Intra-Cellular pH Using Characteristic Absorption of Water by Near-Infrared Spectroscopy

Accurate determination of extra-cellular pH (pHe) and intra-cellular pH (pHi) is important to cancer diagnosis and treatment because tumor cells exhibit a lower pHe and a slightly higher pHi than normal cells. In this work, the characteristic absorption of water in the near-infrared (NIR) region was utilized for the determination of pHe and pHi. Dulbecco’s modified eagle medium (DMEM) and bis (2-ethylhexyl) succinate sodium sulfonate reverse micelles (RM) were employed to simulate the extra- and intra-cellular fluids, respectively. Continuous wavelet transform (CWT) was used to enhance the resolution of the spectra. Quantitative models for pHe and pHi were established using partial least squares (PLS) regression, producing relative errors of validation samples in a range of −0.74–2.07% and −1.40–0.83%, respectively. Variable selection was performed, and the correspondence between the selected wavenumbers and water structures was obtained. Therefore, water with different hydrogen bonds may serve as a good probe to sense pH within biological systems

Evaluation of Hydrogen Permeation into High-Strength Steel during Corrosion in Different Marine Corrosion Zones

Hydrogen permeation into high-strength steel during the corrosion process can deteriorate their mechanical properties, thus seriously threatening the safety of steel structures. However, the hydrogen permeation behavior of steels in corrosive marine environments is not well understood. In this study, the hydrogen permeation behavior and mechanism of AISI 4135 steel in different marine corrosion zones was investigated for the first time using an in situ hydrogen permeation monitoring system via outdoor and indoor tests. The three-month outdoor hydrogen permeation test showed that the diffusible hydrogen content of the steels exposed to the marine atmospheric, splash, tidal and immersion zone was 3.15 × 10−3, 7.00 × 10−2, 2.06 × 10−2 and 3.33 × 10−2 wt ppm, respectively. Meanwhile, results showed that the hydrogen permeation current density was positively correlated with the corrosion rate of the steel in the marine environments. This research is of great significance for guiding the safe application of high-strength steel in the marine environments

Characteristics and mechanisms of low-alloy high-strength steel corrosion behavior under barnacle adhesion based on a comparison experiment

A comparative experiment was set up in a field site and laboratory to study the effect of barnacles (model organisms of macrofouling) on the corrosion behavior of a low-alloy high-strength steel. The results indicated that barnacle adhesion can slow the corrosion rate of steel in an immersion environment by hindering the diffusion of corrosive ions. It was found that barnacle adhesion had a significant promotion effect on localized corrosion. Due to steel’s high corrosion rate, the corrosion-impeding effect was improved, and the promotioneffect on localized corrosion was weakened. The study proposed a corrosion mechanism model influenced by barnacles

Bone Marrow-Derived Mesenchymal Stem Cells Maintain the Resting Phenotype of Microglia and Inhibit Microglial Activation

<div><p>Many studies have shown that microglia in the activated state may be neurotoxic. It has been proven that uncontrolled or over-activated microglia play an important role in many neurodegenerative disorders. Bone marrow-derived mesenchymal stem cells (BMSCs) have been shown in many animal models to have a therapeutic effect on neural damage. Such a therapeutic effect is attributed to the fact that BMSCs have the ability to differentiate into neurons and to produce trophic factors, but there is little information available in the literature concerning whether BMSCs play a therapeutic role by affecting microglial activity. In this study, we triggered an inflammatory response situation <i>in vitro</i> by stimulating microglia with the bacterial endotoxin lipopolysaccharide (LPS), and then culturing these microglia with BMSC-conditioned medium (BMSC-CM). We found that BMSC-CM significantly inhibited proliferation and secretion of pro-inflammatory factors by activated microglia. Furthermore, we found that the phagocytic capacity of microglia was also inhibited by BMSC-CM. Finally, we investigated whether the induction of apoptosis and the production of nitric oxide (NO) were involved in the inhibition of microglial activation. We found that BMSC-CM significantly induced apoptosis of microglia, while no apoptosis was apparent in the LPS-stimulated microglia. Our study also provides evidence that NO participates in the inhibitory effect of BMSCs. Our experimental results provide evidence that BMSCs have the ability to maintain the resting phenotype of microglia or to control microglial activation through their production of several factors, indicating that BMSCs could be a promising therapeutic tool for treatment of diseases associated with microglial activation.</p></div

Methylenetetrahydrofolate reductase <it>C677T</it> polymorphism is associated with estimated glomerular filtration rate in hypertensive Chinese males

<p>Abstract</p> <p>Background</p> <p>Plasma level of total homocysteine (tHcy) is negatively correlated with kidney function in general population. However, the causal mechanism of this correlation is poorly understood. The purpose of this study is to investigate the association of methylenetetrahydrofolate reductase (<it>MTHFR</it>) <it>C677T</it> gene polymorphism, which is a major genetic determinant of the plasma tHcy level, with estimated glomerular filtration rate (eGFR) in Chinese.</p> <p>Methods</p> <p>A total of 18 814 hypertensive patients (6 914 males, 11 900 females) were included in the study.</p> <p>Results</p> <p>Association between the eGFR and <it>MTHFR C677T</it> genotype was examined by sex-specific regression analyses. In males, TT genotype was associated with 1.37 ml/min/1.73 m² decrease in eGFR (p = 0.004) and with an increased risk (OR = 1.32, p = 0.008) for the lowest quintile of eGFR after adjusting for age, BMI, and blood pressures. However, such association was not observed in females (p > 0.05). This association suggests <it>MTHFR C677T</it> polymorphism may play a role in the regulation of eGFR in males.</p> <p>Conclusions</p> <p><it>MTHFR 677 T</it> is a risk allele for decreased kidney function in Chinese males, implicating this gene in the pathogenesis of chronic kidney disease (CKD).</p

BMSC-induced apoptosis of microglial cells.

<p>We investigated the effects of conditioned medium on apoptosis of microglial cells by TUNEL assay. (A) Cells were observed under a fluorescence microscope (magnification 400×), or stained with DAB and observed under an optical microscope (magnification 400×). We found fewer apoptotic cells in the LPS-treated groups compared with the control groups, while apoptosis was increased in the groups cultured in BMSC-CM. (B) The percentage of apoptotic microglial cells among the total number of microglial cells in each group is shown. Bars represent means plus or minus SD obtained from eight random fields. *P<0.05, **P<0.01, compared with control groups.</p