Alkylene oxide poylmerizations: identification of side reactions and by-products

In this study microwave-assisted anionic ring opening polymerization (ROP) of alkylene oxides is reported. Low molar mass polymers of propylene oxide (PO), butylene oxide (BO) and hexylene oxide (HO) are synthesized by anionic ring opening using various monohydric alcohols as initiators. The monohydric alcohols and lower molar masses allowed for monitoring of different types of possible unwanted by-products and their sources. Liquid chromatography at critical conditions (LCCC) and liquid adsorption chromatography (LAC) are used to determine the presence of oligomers other than targeted. Finally, MALDI-TOF MS of the products have clearly shown the trends and extents of different types of side reactions that are possible in anionic ring opening of alkylene oxides. Propylene oxide is most vulnerable to chain transfer reactions compared to higher alkylene oxide.     

Luminescent and transport properties of metastable quaternary compounds in the Cd,M<Superscript>III</Superscript> || S,Te (M<Superscript>III</Superscript> = In,Ga) systems

Metastable quaternary compounds in the reciprocal systems Cd, M || S, Te (M = In, Ga) are prepared by liquid quenching, and their luminescent and transport properties are studied for the first time. Cd₃In₂S₂Te₄, Cd₃Ga₂S₂Te₄, Cd₂Ga₂S₂Te₃, and CdGa₂S₂Te₂ are photosensitive and exhibit efficient near-IR or red (CdGa₂S₂Te₂) luminescence. The properties of the compounds Cd₂M₆S₂Te₉ (M = In, Ga) are also described. All of the synthesized compounds are semiconductors. Their band gaps are evaluated from luminescence data. The peak positions in their luminescence spectra are found to be composition-independent within the homogeneity ranges of Cd₃M₂S₂Te₄Cd₅M₂S₂Te₆ (M = In, Ga).Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1427–1430.Original Russian Text Copyright © 2004 by Odin, Chukichev, Rubina     

Design, Fabrication, and Multiplexing of Magnetic Calorimeter X-ray Detectors with High-Efficiency SQUID Readout

Metallic magnetic calorimeters, where deposited energy is detected by measuring a temperature-dependent magnetization with a low-noise SQUID, remain a promising potential route to X-ray spectrometers with energy resolution approaching 1 eV. In this paper we describe our recent work toward array-compatible, high-resolution MMCs fabricated entirely using thin-film techniques. We describe a meander-style pickup loop designed for good coupling to high-efficiency, low noise SQUIDs, as well as considering various routes to a thin-film paramagnetic sensor. We also briefly overview the most promising technology for multiplexing arrays of non-dissipative metallic magnetic calorimeters.      

Influence of pH, curing time and environmental stress on the immobilization of hazardous waste using activated fly ash

The current work is related to inorganic species in sludge generated from Common Effluent Treatment Plant contaminated with hazardous wastes at relatively high concentration. The environmental sensitive metals studied in the sludge are Pb, Fe, Ni, Zn and Mn. The solidification/stabilization (S/S) of heavy metals within fly ash-cement-based matrix was conducted for low cost treatment and reuse of sludge. The study examines the strength of the S/S product by predicting the effect of supplementary cementing material from efficiency factor (k) at 60 degrees C curing temperature. The leaching test was performed at two different pH 7 and 4 to determine the efficiency of heavy metal immobilization. It was observed that replacing 76% OPC by 56% fly ash and 20% sludge for 28 days curing period shows increase in strength as well as rate of stabilization for zinc, iron and manganese at pH 7, lead and nickel were stabilized by 79 and 82%, respectively. Environmental stress test was performed to evaluate the tolerance of extreme adverse environmental condition.     

Preparation and characterization of biomedical collagen–chitosan scaffolds with entrapped ibuprofen and silver nanoparticles

In this work, the preparation and characterization of a novel multifunctional collagen–chitosan material containing silver nanoparticles and nonsteroid anti‐inflammatory drug ibuprofen is described. As a starting material, the commercially available collagen–chitosan scaffold was used. Drug‐loading procedure was performed via supercritical CO₂‐assisted impregnation technique. Silver nanoparticles were prepared via metal vapor synthesis and introduced into the composite biopolymer matrix. An analysis of the small‐angle X‐ray scattering profiles revealed that silver nanoparticles are characterized by having a logarithmic normal size distribution with the maximum at 25 nm. The average size of particles determined from the broadening of diffraction peaks is in a good agreement with this result. The surface of the materials was characterized by X‐ray photoelectron spectroscopy. The in vitro release kinetics of ibuprofen in phosphate buffer solution with pH = 7.4 from prepared materials was studied. The drug release to solution is governed by Fickian diffusion and can be described within the Ritger–Peppas model. Introduction of silver nanoparticles has no effect on the diffusion mechanism. The as‐prepared materials are promising for the medical applications such as dressings for treatments of infected wounds and infection preventing. These materials can act as a matrix for transdermal drug administration. POLYM. ENG. SCI., 59:2479–2487, 2019. © 2019 Society of Plastics Engineers     

Multifunctional 3D‐Printed Patches for Long‐Term Drug Release Therapies after Myocardial Infarction

A biomaterial system incorporating nanocellulose, poly(glycerol sebacate), and polypyrrole is introduced for the treatment of myocardial infarction. Direct ink writing of the multicomponent aqueous suspensions allows multifunctional lattice structures that not only feature elasticity and electrical conductivity but enable cell growth. They are proposed as cardiac patches given their biocompatibility with H9c2 cardiomyoblasts, which attach extensively at the microstructural level, and induce their proliferation for 28 days. Two model drugs (3i‐1000 and curcumin) are investigated for their integration in the patches, either by loading in the precursor suspension used for extrusion or by direct impregnation of the as‐obtained, dry lattice. In studies of drug release conducted for five months, a slow in vitro degradation of the cardiac patches is observed, which prevents drug burst release and indicates their suitability for long‐term therapy. The combination of biocompatibility, biodegradability, mechanical strength, flexibility, and electrical conductivity fulfills the requirement of the highly dynamic and functional electroresponsive cardiac tissue. Overall, the proposed cardiac patches are viable alternatives for the regeneration of myocardium after infarction through the effective integration of cardiac cells with the biomaterial.     

Synthesis and optimization of soy protein fiber based graft copolymer through response surface methodology for removal of oil spillage

Present study deals with the development of novel biodegradable polymer device for petroleum fraction removal from different petroleum-saline emulsion. Soy protein fiber was graft copolymerized with poly(methylmethacrylate) using sequential experimental design approach. Six process variables, such as solvent amount, monomer concentration, FAS:KPS ratio, reaction time, reaction temperature, and pH were taken at two levels as per Resolution-V design. Significant process variables were monomer concentration, reaction temperature, and pH. In phase-2, screened variables were taken for model building and optimization as per optimal response surface design. At optimum conditions (monomer concentration: 3.10 mmol L^?1; reaction temperature: 84.2 °C; pH 6.03), the graft percentage was found to be 272 %. Graft copolymer was characterized using FTIR, SEM, TGA, DTA, and DTG techniques. Further, graft copolymer was evaluated for acid–base and moisture resistance behavior. The synthesized soy protein fiber based polymer showed 76–70 % petroleum fraction absorption from different petroleum-saline emulsions.     

Leaching behavior and immobilization of heavy metals in solidified/stabilized products

Solidification/stabilization (S/S) of hazardous sludge from steel processing plant has been studied. Mechanical strength and leaching behavior test of solidified/stabilized product was performed. Mechanical strength decreases with increase in waste content. Pb, Zn, Cu, Fe and Mn could be considerably immobilized by the solidification/stabilization process. The elements least immobilized were Na, K, and Cl. Leaching of heavy metals in the S/S matrix can be considered as pH dependent and corresponding metal hydroxide solubility controlled process. Geochemical modeling was performed for the prediction of speciation. On the basis of test results, mobility and mechanism of leaching was assessed. Dominant leaching mechanism was surface wash off in the initial stages followed by diffusion for Pb, Zn, Cu, Fe and Mn. Diffusion coefficient was above 11.5 indicating low mobility in the cement matrix.