Emulsifier‐free reversible addition–fragmentation chain transfer emulsion polymerization of alkyl acrylates mediated by symmetrical trithiocarbonates based on poly(acrylic acid)

Emulsifier‐free batch emulsion polymerization of n‐butyl acrylate and its semi‐batch copolymerization with 2,2,3,3,4,4,5,5‐octafluoropentyl acrylate and 2,2,3,4,4,4‐hexafluorobutyl acrylate both mediated by poly(acrylic acid) containing the trithiocarbonate group in the chain was employed to produce amphiphilic triblock copolymers. The polymerization‐induced self‐assembly of these copolymers in aqueous media gave rise to spherical core–shell particles. Irrespective of the experimental conditions, the polymeric product was characterized by a bimodal molecular weight distribution. The apparent violation of the reversible addition–fragmentation chain transfer polymerization mechanism may be attributed to restricted accessibility of the trithiocarbonate group in the self‐assembled block copolymers for propagating radicals that enter into the particle. Mean‐field theoretical arguments were employed to explain the exclusively spherical morphology of the particles observed in the experiment. © 2019 Society of Chemical Industry     

Analysis of saturation currents and barrier height of Ta2O5 doped based on Ba0,5S0,5TiO3 photodiode

Ba_0,5Sr_0,5TiO₃ (BST) thin films have been prepared on Si (100) p-type substrates using a chemical solution deposition (CSD) method and doped with 0%, 2.5%, 5%, 7.5%, 10% tantalum pentaoxide (Ta₂O₅). Chemical Solution Deposition Method (CSD) used the spin coating techniques with a rotational speed of 3000?rpm for 30?seconds. BST thin films annealed at a temperature 850?°C. Various electrical parameters such as saturation current, series resistance and barrier height have been calculated from the analysis of experimental I–V results and discussed in detail. The series resistance was found from the experiment of 42.8 MΩ, 7.9 MΩ, 7.2 MΩ, 2.03 MΩ, 1.2 MΩ for variation doping content. The saturation current of 22.3 μA, 2.7 μA, 9.7 μA, 4.82 μA, 4.50 μA was obtained in BST thin film with variation doping content. Then, the barrier height of 0.56?eV, 0.62?eV, 0.58?eV, 0.54?eV, 0.60?eV was obtained in BST thin film with variation doping content. The optical characterization and analysis microstructure such as XRD, EDX were discussed in detail.     

Porous calcium phosphate ceramic granules and their behaviour in differently loaded areas of skeleton

Two kinds of calcium phosphate ceramic (CPC) granules of high porosity (50 ± 5%) and improved (for such materials) compressive strength (10–25 MPa) consisted of hydroxyapatite (PHA) and a mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) in 60 HA/40 β-TCP composition (PCPC) were developed. A comparative study of in vivo behavior of the materials implanted into an almost unloaded (greater trochanter of femur) and loaded (distal methaphysis of femur) zones in the skeleton of rabbits was performed. Significant activating influence of loading on the processes of new bone formation and reconstruction in macropores of both materials during all periods of implantation (up to 6 months) was observed. The role of relevant cells in the processes in the unsoluble PHA and the degradable PCPC (in which the processes was observed to intensify due to dissolution of the material) was studied and is discussed. Great disturbance in pore structure of the BCPC was revealed in more late periods of implantation. After 6 months, presence of large composite fragments located in intertrabecula spaces of greater trochanter was a characteristic feature of the PCPC crushing. The developed CPC materials seems to have good perspective for using in bone defect plasty in some loaded areas of the skeleton.     

The P300 as an electrophysiological probe of alcohol expectancy.

Language-based measures indicate that alcohol expectancies influence alcohol consumption. To relate these measures to brain actions that precede verbal output, the P300 component of the Event-related potentials (ERPs) was used to detect violations of individually held alcohol expectancies. As predicted, P300 amplitude elicited by negative alcohol expectancy stimuli was positively correlated with endorsement of positive/arousing alcohol expectancies on the language-based measures, such that the higher an individual's positive/arousing expectancies, the larger was the P300 elicited by negative alcohol expectancy stimuli. These results demonstrated concordance between language-based measures of alcohol expectancies and electrophysiological probes of expectancy. While it remains unknown whether these expectancy processes are integral to decision pathways that influence consumption, these findings suggest that such processing can occur very quickly outside of conscious deliberation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biodegradable Polymers, 9. Technologically Relevant Aspects of Kinetics and Mechanism of Ring‐Opening Polymerization of L,L‐Dilactide

Poly(L ‐lactide) is manufactured by a cascade process comprising the fermentation of glucose substrate, oligomerization of L ‐lactic acid, cyclization depolymerization to L ,L ‐dilactide and ring‐opening polymerization of the cyclic diester. The process development requires detailed knowledge of kinetics, thermodynamics and reaction mechanism in all process stages. This paper aims to show the influence of micro‐ and macrokinetic factors on the course of the ring‐opening polymerization and the molecular parameters of the formed polyester. Monomer conversion and molecular weight of the polyester are determined by chemically active process parameters, like kind and concentration of catalyst and initiator, respectively, reaction temperature or presence of cocatalysts as well as by the intensity of mixing of the polymerizing melt. The highest polymerization rate is observed in presence of tin octoate, but this catalyst leads to a fast degradation of the formed polymer.     

Stem Cell Therapy Enhances Motor Activity of Triceps Surae Muscle in Mice with Hereditary Peripheral Neuropathy

Impaired motor and sensory functions are the main features of Charcot–Marie–Tooth disease. Mesenchymal stem cell (MSCs) therapy is one of the possible treatments for this disease. It was assumed that MSCs therapy can improve the contractile properties of the triceps surae (TS) muscles in mice with hereditary peripheral neuropathy. Murine adipose-derived mesenchymal stromal cells (AD-MSCs) were obtained for transplantation into TS muscles of FVB-C-Tg(GFPU)5Nagy/J mice. Three months after AD-MSCs transplantation, animals were subjected to electrophysiological investigations. Parameters of TS muscle tension after intermittent high frequency electrical sciatic nerve stimulations were analyzed. It was found that force of TS muscle tension contraction in animals after AD-MSCs treatment was two-time higher than in untreated mice. Normalized values of force muscle contraction in different phases of electrical stimulation were 0.3 ± 0.01 vs. 0.18 ± 0.01 and 0.26 ± 0.03 vs. 0.13 ± 0.03 for treated and untreated animals, respectively. It is assumed that the two-fold increase in TS muscle strength was caused by stem cell therapy. Apparently, AD-MSCs therapy can promote nerve regeneration and partial restoration of muscle function, and thus can be a potential therapeutic agent for the treatment of peripheral neuropathies.     

Cleaning UF membranes with simple and formulated solutions

The ultrafiltration membranes fouled by proteins are typically cleaned by consecutive soaking in alkali, surfactant and oxidizing solutions. We combined all three chemicals into a formulated cleaning agent and examined its efficiency to restore the water flux without damaging the membrane or enhancing protein fouling. Lower concentrations of ingredients in the composite were required to restore the water flux to the initial level. The membrane after the cleaning remained intact and subsequent filtration left trace protein amount on the membrane surface. We propose a mechanism of cleaning based on a fast penetration of alkali and oxidizing ingredients through a fouling layer and efficient micellation of detached foulants with surfactant.     

Pseudotransient Continuation-Based Steady State Solver: Extension to Zero Flow Rates

This paper presents and discusses an extension of the pseudotransient continuation-based steady state solver for hydraulic networks proposed previously to the case of zero flow rates. The original solver, which reduces the solution of the governing nonlinear algebraic equations to the numerical integration of an initial-value problem, has problems in situations in which the head derivative of the flow rate tends to infinity, as is the case with zero flow rates. The extension is on the basis of the use of a model headloss-flow relationship that coincides with the true one at zero and has a finite head derivative at that point. This modified steady state solver is free from some convergence problems that occur in Newton-Raphson method-based solvers when analyzing a pipe network with control devices. The paper includes the results of the numerical analysis of test networks, which demonstrate the convergence of the modified steady state solver for cases in which existing steady state solvers have troubles.     

Synthesis of cross‐linked polyethylene oxide‐acetal macrocycles for solid superbase catalysts

A novel long‐chain divinyl ether of tris(diethyleneglycol)‐bisacetal, has been synthesized by electrophilic addition of one molecule of diethylene glycol to two molecules of divinyl ether of diethylene glycol (DVDEG) in the presence of CF₃COOH in quantitative yield. The monomer was cationically polymerized (BF₃·OEt₂, or complex LiBF₄·MeO(CH₂)₂OMe) and copolymerized with DVDEG to deliver solid polymers the yields being 80–100%. The polymers represent the cross‐linked polyether‐polyacetal structures comprising macrocycles. The polymers were treated with 3% solution of KOH or CsOH in methanol to afford solid superbase complexes of KOH (CsOH) with cross‐linked polyether‐polyacetal macrocyclic networks. Preliminary tests have shown the complexes to be active catalysts for ethynylation of acetones and prototropic isomerization of methyl propargyl ethers to allenyl methyl ethers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011