Influence of arsenic on the corrosion resistance of low-carbon low-alloy steel. Part 2

Literature data regarding the influence of arsenic on the corrosion resistance of low-carbon low-alloy steel are analyzed. A mechanism explaining this influence in air and in sea water is proposed.     

Mathematical model for choosing the preferable range of concentrations of ligands as components of solutions for alloy electrodeposition

Based on a statistical analysis of the information on the composition of solutions for the electrodeposition of A-B alloys, a mathematical model is proposed that makes it possible to choose the preferable range of the total concentrations of ligands in solutions for alloy electrodeposition. The prediction by the model is verified by known and new experimental data.     

Cerebrovascular and cardiovascular responses to graded tilt in patients with autonomic failure

BACKGROUND AND PURPOSE: Patients with autonomic nervous system failure often experience symptoms of orthostatic intolerance while standing. It is not known whether these episodes are caused primarily by a reduced ability to regulate arterial blood pressure or whether changes in cerebral autoregulation may also be implicated. METHODS: Eleven patients and eight healthy age- and sex-matched control subjects were studied during a graded-tilt protocol. Changes in their steady state middle cerebral artery mean flow velocities (MFV), measured by transcranial Doppler, brain-level mean arterial blood pressures (MABPbrain), and the relationship between the two were assessed. RESULTS: Significant differences between patients and control subjects (P < .05) were found in both their MFV and MABPbrain responses to tilt. Patients' MFV dropped from 60 +/- 10.2 cm/s in the supine position to 44 +/- 14.0 cm/s at 60 degrees head-up tilt, whereas MABPbrain fell from 109 +/- 11.7 to 42 +/- 16.9 mm Hg. By comparison, controls' MFV dropped from 54 +/- 7.8 cm/s supine to 51 +/- 8.8 cm/s at 60 degrees, whereas MABPbrain went from 90 +/- 11.2 to 67 +/- 8.2 mm Hg. Linear regression showed no significant difference in the MFV-MABPbrain relationship between patients and control subjects, with slopes of 0.228 +/- 0.09 cm.s-1.mm Hg-1 for patients and 0.136 +/- 0.16 cm.s-1.mm Hg-1 for control subjects. CONCLUSIONS: The present study found significant differences between patients and control subjects in their MFV and MABPbrain responses to tilt but no difference in the autoregulatory MFV-MABPbrain relationship. These results suggest that patients' decreased orthostatic tolerance may primarily be the result of impaired blood pressure regulation rather than a deficiency in cerebral autoregulation.     

Correction to: Hydrodynamic Tests of Small-Sized Circulating Water Cooling Devices

Chemical and Petroleum Engineering - To the article “Hydrodynamic Tests of Small-Sized Circulating Water Cooling Devices,” by K. E. Bondar’, N. S. Shulaev, and S. P. Ivanov, Vol....     

pH-Dependent Protonation of Surface Carboxylate Groups in PsbO Enables Local Buffering and Triggers Structural Changes

Photosystem II (PSII) catalyzes the splitting of water, releasing protons and dioxygen. Its highly conserved subunit PsbO extends from the oxygen-evolving center (OEC) into the thylakoid lumen and stabilizes the catalytic Mn₄CaO₅ cluster. The high degree of conservation of accessible negatively charged surface residues in PsbO suggests additional functions, as local pH buffer or by affecting the flow of protons. For this discussion, we provide an experimental basis, through the determination of pK_a values of water-accessible aspartate and glutamate side-chain carboxylate groups by means of NMR. Their distribution is strikingly uneven, with high pK_a values around 4.9 clustered on the luminal PsbO side and values below 3.5 on the side facing PSII. pH-dependent changes in backbone chemical shifts in the area of the lumen-exposed loops are observed, indicating conformational changes. In conclusion, we present a site-specific analysis of carboxylate group proton affinities in PsbO, providing a basis for further understanding of proton transport in photosynthesis.     

Sulfonation of (glycidyl methacrylate) chains grafted onto nonwoven polypropylene fabric

Sulfonation of polyglycidyl methacrylate (PGMA) chains grafted onto nonwoven polypropylene fabric is investigated in detail. Sulfonation reaction consists in implantation of sulfonate groups via epoxy ring‐opening of PGMA chains grafted onto nonwoven polypropylene fabric by reaction between the GMA‐grafted sample and sodium hydrogensulfite in water–dimethylformamide solution. On the basis of analyses of IR spectra of the appropriate samples and data of backward titration, two simultaneous processes are demonstrated to take place during the sulfonation reaction. These processes are the implantation of sulfonate groups via opening of the GMA epoxy rings and hydrolysis of the GMA epoxy rings with α‐glycol groups formation. The main peculiarities of the sulfonation reaction in depending on the GMA grafting degree are reported. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Nanostructuring Lipophilic Dyes in Water Using Stable Vesicles,Quatsomes, as Scaffolds and Their Use as Probes for Bioimaging

A new kind of fluorescent organic nanoparticles (FONs) is obtained using quatsomes (QSs), a family of nanovesicles proposed as scaffolds for the nanostructuration of commercial lipophilic carbocyanines (1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine perchlorate (DiI), 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl‐indodicarbocyanine perchlorate (DiD), and 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl‐indotricarbocyanine iodide (DiR)) in aqueous media. The obtained FONs, prepared by a CO₂‐based technology, show excellent colloidal‐ and photostability, outperforming other nanoformulations of the dyes, and improve the optical properties of the fluorophores in water. Molecular dynamics simulations provide an atomistic picture of the disposition of the dyes within the membrane. The potential of QSs for biological imaging is demonstrated by performing superresolution microscopy of the DiI‐loaded vesicles in vitro and in cells. Therefore, fluorescent QSs constitute an appealing nanomaterial for bioimaging applications.     

Titanium-boride eutectic materials: Phase equilibria and properties of alloys in the Ti-rich portion of the Ti–Sn–B system

Phase equilibria in the Ti–TiB–Ti₃Sn region of the Ti–Sn–B system were experimentally investigated in the melting (solidification) temperature range using metallography (including EPMA), XRD, DTA, and pyrometry. The phase diagram is presented as solidus and liquidus surfaces projections and a vertical section through the 7.5 at.% B. The Sn alloying was found to have a profound hardening effect on the eutectic titanium-boride alloys.