Dehydrochlorination of PVC Compositions During Thermal Degradation

The polyvinylchloride (PVC) differs from other polymer materials by low thermostability. The process of dehydrochlorination takes place even at low temperatures. The purpose of this investigation was to determine the influence of different PVC additives on formation of hydrogen chloride (HCl) from thermal degradation in different gaseous fluids. It has been established that the HCl formation takes place more in nitrogen as a medium than in air medium at a given temperature, especially for the high temperature region. Dibutyl phthalate (as a plasticizer) in 25 mass % w.r.t. PVC, reduces the mass loss due to HCl formation by about 5%, which is the result of two interaction processes - between HCl and plastifier degradation products. It has been found that the addition of 5 mass % of stabilizer in PVC slows down the process of dehydrochlorination and as a result the loss of mass is 2-5% less, compared to non-stabilized samples. Calcium carbonate as a filler was found to be active above 400-500 °C and reduction in mass loss was found to be up to 15% at a temperature range of 800-900 °C. Calculation of kinetic parameters shows that the rate of dehydrochlorination depends on the composition of PVC. The activation energy of formation of HCl in air, in a temperature range of 400-600 °C has been found to be 12.7, 13.3, 16.1 kJ/mol for pure, plasticized and stabilized PVC, respectively. The results reported here shall be useful for development of methods for waste utilization and their influence on the environment

Synthesis and Properties of Peroxy Oligomers Obtained by Telomerization Effects of the Presence of Bases

New bifunctional oligomers bearing peroxy groups have been synthesized by telomerization in one step reaction. For obtaining oligoperoxides (PO) by telomerization method, epoxide compounds will react with substances containing labile hydrogen atom. Using the principle of stochiometric imbalance between diepoxy compounds and substances with mobile hydrogen atoms and employing a functional peroxide as telogen, the synthesis of PO was studied. 2,2–Di[4–(2,3–epoxy–1-propoxy)phenyl]–propane (diglycidyl ether of diphenylol propane - DGEDPP), 1,2–Di (2,3–epoxy–1-propoxy) ethane (diglycidyl ether of ethylene glycol -DGEEG) and 1,2–Epoxy–3–tert–butylperoxypropane (EP) have been synthesized by methods reported in the literature. Chemical structures have been confirmed by NMR and FTIR, number-average molecular weights Mn of POs by cryoscopy, active oxygen content [O]act. for POs was determined by iodometry and epoxy number (e.n.) for POs was measured via direct titration of PO samples. A 50% solution of potassium or sodium isopropylates in 2-propanol is used to catalyze the telomerisation. Different parameters such as ratio of components, temperature, reaction time have been optimized in vu to get well defined peroxy oligomers. The presence of peroxy groups in synthesized POs allows us to employ these compounds as curing agents for polymers containing unsaturated double bonds and may be used to improve performance of unsaturated polyester GFR systems

Subconjunctival Injection of XG-102, a c-Jun N-Terminal Kinase Inhibitor Peptide, in the Treatment of Endotoxin-Induced Uveitis in Rats.

Abstract Purpose: XG-102, a TAT-coupled dextrogyre peptide inhibiting the c-Jun N-terminal kinase, was shown efficient in the treatment of experimental uveitis. Preclinical studies are now performed to determine optimal XG-102 dose and route of administration in endotoxin-induced uveitis (EIU) in rats with the purpose of clinical study design. METHODS: EIU was induced in Lewis rats by lipopolysaccharides (LPS) injection. XG-102 was administered at the time of LPS challenge by intravenous (IV; 3.2, 35 or 355 μg/injection), intravitreal (IVT; 0.08, 0.2 or 2.2 μg/eye), or subconjunctival (SCJ; 0.2, 1.8 or 22 μg/eye) routes. Controls received either the vehicle (saline) or dexamethasone phosphate injections. Efficacy was assessed by clinical scoring, infiltrating cells count, and expression of inflammatory mediators [inducible nitric oxide synthase (iNOS), cytokine-induced neutrophil chemoattractant-1 (CINC-1)]. The effect of XG-102 on phosphorylation of c-Jun was evaluated by Western blot. RESULTS: XG-102 demonstrated a dose-dependent anti-inflammatory effect in EIU after IV and SCJ administrations. Respective doses of 35 and 1.8 μg were efficient as compared with the vehicle-injected controls, but only the highest doses, respectively 355 and 22 μg, were as efficient as dexamethasone phosphate. After IVT injections, the anti-inflammatory effect of XG-102 was clinically evaluated similar to the corticoid's effect with all the tested doses. Regardless of the administration route, the lowest efficient doses of XG-102 significantly decreased the ration of phospho c-Jun/total c-Jun, reduced cells infiltration in the treated eyes, and significantly downregulated iNOS and CINC-1 expression in the retina. CONCLUSION: These results confirm that XG-102 peptide has potential for treating intraocular inflammation. SCJ injection appears as a good compromise to provide a therapeutic effect while limiting side effects

Some Peculiarities of Creation of Stable Polyimide - Azo Chromophore System

Azo dyes: methyl orange, methyl red, congo red have been suggested as doping agents for formulation of stable soluble azo dye - polyimide (PI) system according to guest-host scheme. The dyes were added to the reactive mixture of monomers: dianhydrides of alicyclic tetracarboxylic acids and aromatic diamines. Polyimide synthesis was carried out by one step polycyclocondensation in protolytic media. Addition of azo dyes influences on the molecular weights of final PIs. In great extent they depend on the nature and  concentration of doping agent. Investigation of dependence of reduced viscosity of PI on monomers concentration, duration and temperature of synthesis, concentration of doping agent. It has been determined that addition of dyes to the reaction mixture up to definite value rises molecular weights of PIs from 45-50 000 up to 320-330 000. The most efficient catalyst is congo red. However some functional groups of azo dyes disturb equimolarity of the reaction by interaction with one of main monomers. The colour of thus doped PIs is stable under processing and high temperatures. Stability of the azo dye - polyimide system depends on interaction of NLO agent with polyimide chain. It is suggested that congo red molecules can coordinate with carbonyl groups of polymer. PI films display solvatochromic properties

Catalysis of Trans-esterification Reactions in Model Ester Mixtures

Model trans-esterification reaction of n-butylbenzoate with phenyl-p-chlorobenzoate in the molar ratio of 20:1 has been studied. In order to evaluate catalysts based on lanthanide system the activity of nyodymium compounds – neodymium acetate, neodymium acetylacetonate and nitrate complex with benzo-12-crown-4 (neodymium nitrate coronate) – has been studied in the model trans-esterification reaction of n-butylbenzoate with phenyl-pchlorobenzoate. The effect of the electronic structure of the metal on the catalytic activity of the coronates of lanthanum, cerium, praseodymium, neodymium, samarium, terbium and erbium nitrates has been studied. In order to estimate the optimum concentration of the catalysts, a study of the dependence of the transesterification reaction on concentration of neodymium nitrate coronate was carried out. An asymptotic nature of the concentration dependence on the catalytic activity of lanthanide compounds has been observed. In order to look for new classes of inhibitors of trans-esterefication reaction, the model trans-esterificatiom reaction of n-butylbenzoate with phenyl-p-chlorbenzoate has been studied in the presence of some carborane derivatives: cesium salts of bis-1,2-(dicarbollyl) complexes of iron, cobalt and nickel(3+) and bis-1,2(dicarbollyl) nickel(4+) [(C2B9H11)2Me]. Some of these compounds were found to be effective inhibitors. The dependence of the constant rate of the model trans-esterification reaction of n-butylbenzoate with phenyl-p-chlorobenzoate on the concentration of cerium salt of bis-1,2-(dicarbollyl) complex of nickel has been studied to determine the optimum concentration of inhibitors. The influence of the ester chemical structure on the activity of ester groups in the trans-esterification activity has been determined in the reaction of di-n-butylterephthalate with different p-substituted derivatives of phenylbenzoate (phenyl-p-methoxybenzoate, phenyl-p-methylbenzoate, phenylbenzoate, phenyl- pchlorobenzoate, phenyl-p-nitrobenzoate, p-methoxyphenylbenzoate, p-methylphenylbenzoate, p-chlorophenylbenzoate, p-nitrophenylbenzoate, n-butylbenzoate, di-n-butylterephthalate) in presence of the samarium nitrate coronate

Synthesis of Diblocks Copolymers PCL-b-PLLA and Optimization of its Mechanical Characteristics

Biodegradable polymeric materials have a wide application in medicine, ecology and a number of other branches of industry. Overwhelming majority of such polymers is well exposed to the biodegradation, but they have mechanical properties which don’t correspond to the requirements of application areas. As a rule, these materials possess low elasticity. In this work, optimization of mechanical properties of biodegradable polymers and the search of structure of block polymer on the basis of e-caprolactone and L-lactide with the maximal elasticity are considered. The purpose of the work is to receive the diblock polymer with mechanical properties as close as possible to elastomer for medical devices. The task is reached due to application of design of experiment with the subsequent optimization of the received results. Maximization of elongation at maximum load of received polymer is solved by the greatest possible reduction of crystallinity with a variation of molar weight of both part of diblock: polycaprolactone and polylactide. The absolute maximum of elongation at maximum load of synthesized diblock polymers is found. It is established that diblock with the following structure possesses the best mechanical properties in this class of polymers. Molar weight of the polycaprolactone block is 5000 Da while polylactide block is 7000 Da. Elongation at maximum load of this polymer was about 30%. In the second stage of our research, we try to improve the mechanical properties by making one block partly random (PCL-co-PLLA). Second block was made from homopolymer (PLLA). Maximum received elongation at break is 200%. First block of this polymer contains 25% of lactide, has molar weight of 10000 Da. Second block is the pure polylactide, with molar weight 10000 Da. All the experimental results and mathematical modeling pointing direction to maximum elongation could be achieved by multi-block structures

A review of spatial causal inference methods for environmental and epidemiological applications

The scientific rigor and computational methods of causal inference have had great impacts on many disciplines, but have only recently begun to take hold in spatial applications. Spatial casual inference poses analytic challenges due to complex correlation structures and interference between the treatment at one location and the outcomes at others. In this paper, we review the current literature on spatial causal inference and identify areas of future work. We first discuss methods that exploit spatial structure to account for unmeasured confounding variables. We then discuss causal analysis in the presence of spatial interference including several common assumptions used to reduce the complexity of the interference patterns under consideration. These methods are extended to the spatiotemporal case where we compare and contrast the potential outcomes framework with Granger causality, and to geostatistical analyses involving spatial random fields of treatments and responses. The methods are introduced in the context of observational environmental and epidemiological studies, and are compared using both a simulation study and analysis of the effect of ambient air pollution on COVID-19 mortality rate. Code to implement many of the methods using the popular Bayesian software OpenBUGS is provided

A peptide inhibitor of c-Jun N-terminal kinase for the treatment of endotoxin-induced uveitis.

PURPOSE: To evaluate the effect of XG-102 (formerly D-JNKI1), a TAT-coupled dextrogyre peptide that selectively inhibits the c-Jun N-terminal kinase, in the treatment of endotoxin-induced uveitis (EIU). METHODS: EIU was induced in Lewis rats by LPS injection. XG-102 was administered at the time of LPS challenge. The ocular biodistribution of XG-102 was evaluated using immunodetection at 24 hours after either 20 microg/kg IV (IV) or 0.2 microg/injection intravitreous (IVT) administrations in healthy or uveitic eyes. The effect of XG-102 on EIU was evaluated using clinical scoring, infiltration cell quantification, inducible nitric oxide synthase (iNOS) expression and immunohistochemistry, and cytokines and chemokines kinetics at 6, 24, and 48 hours using multiplex analysis on ocular media. Control EIU eyes received vehicle injection IV or IVT. The effect of XG-102 on c-Jun phosphorylation in EIU was evaluated by Western blot in eye tissues. RESULTS: After IVT injection, XG-102 was internalized in epithelial cells from iris/ciliary body and retina and in glial and microglial cells in both healthy and uveitic eyes. After IV injection, XG-102 was concentrated primarily in inflammatory cells of uveitic eyes. Using both routes of administration, XG-102 significantly inhibited clinical signs of EIU, intraocular cell infiltration, and iNOS expression together with reduced phosphorylation of c-Jun. The anti-inflammatory effect of XG-102 was mediated by iNOS, IFN-gamma, IL-2, and IL-13. CONCLUSIONS: This is the first evidence that interfering with the JNK pathway can reduce intraocular inflammation. Local administration of XG-102, a clinically evaluated peptide, may have potential for treating uveitis

Programme de recherche sur le traitement et l'elimination des boues residuaires 3ere tranche annuelle

SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3305) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc