Sintering behaviour and hydration resistance of reactive dolomite

Sintering of raw dolomite and hydroxides derived from dolomite was carried out in the temperature range 1350-1650 °C. The hydroxide derived from dolomite was developed through pre-calcination of dolomite followed by its hydration. For hydroxide development, after precalcination one sample was air-quenched and the other powder was furnace cooled before hydration. The air quenched samples showed better densification than that of the furnace cooling process at the same temperature. Fe₂O₃ addition enhances sintering by liquid formation at higher temperature. The grain size of doloma with Fe₂O₃ addition is bigger than that without additive. Hydration resistance was related to densification and grain size of sintered dolomite.     

Microencapsulation of reactive amine by interfacially engineered epoxy microcapsules for smart applications

The most common approach for incorporation of extrinsic self-healing functionality relies on introducing healant-loaded micro-containers in the polymeric formulation. In this context, a healing system based on encapsulated epoxy resin and amine hardener appears to be one of the most economically viable solutions, in view of the chemical as well as mechanical compatibility with the matrix. Encapsulation of epoxy resins has been extensively studied while the high reactivity of the amine hardener renders its encapsulation rather difficult and has been attempted with only modest success. The purpose of the present work is to adopt an interfacial polymerization approach for the preparation of epoxy microcapsules encapsulating a reactive amine hardener (triethylene tetramine). The effects of experimental parameters, including reaction temperature, stirring speed and epoxy/amine concentration ratio on the microcapsule formation were investigated. A polymeric surfactant was used to stabilize the suspension to modulate the particle size distribution of the resultant microcapsules. The highest encapsulation efficiencies were obtained when the reaction medium was maintained at 70 °C under stirring (600 rpm) at epoxy/amine ratio of 10/3.2. The microcapsule dimensions and core content could be tailored, following this encapsulation approach of interfacial polymerisation. Under optimal conditions, spherical microcapsules with 100% yield and 12% core content were obtained.     

Study of nitric acid leachout characteristics from weak base anion exchanger to maintain a specified pH regime during Gd(NO3)3 removal from moderator system of 540 MWe PHWRs

Nitric acid leachout characteristics from weak base anion exchanger (WBA) have been experimentally evaluated as a function of total nitric acid loading at a given flow velocity. An empirical first order model is used to explain the column outlet behaviour. Based on the experimental evaluation, a column configuration of a strong acid cation exchanger (SAC) topped mixed bed of SAC and WBA followed by a 5% nitric acid loaded WBA as the bottom layer of the column has been used to remove Gd(NO₃)₃ from water while maintaining the column outlet pH in the range of 5.0–5.5.     

Hot Ductility and Deformation Behavior of C-Mn/Nb-Microalloyed Steel Related to Cracking During Continuous Casting

Hot ductility studies have been performed on C-Mn and C-Mn-Nb steels with an approach to simulate the effect of cooling conditions experienced by steel in secondary cooling zone during continuous casting. Thermal oscillations prior to tensile straining deteriorate hot ductility of steel by deepening and widening the hot ductility trough. C-Mn steels are found to exhibit ductility troughs in three distinct zones whereas C-Mn-Nb steel shows drop in ductility only at low temperature in the vicinity of ferrite transformation temperatures. Start of ferrite transformation in steels causes yield ratio to increase while work hardening rates and strength coefficient decrease with decrease in test temperature in presence of thermal oscillation prior to tensile testing. Inhibition of recrystallization due to build-up of AlN particles along with the presence of MnS particles in structure and low work hardening rates causes embrittlement of steel in austenitic range. Alloying elements enhancing work hardening rates in austenitic range can be promoted to improve hot ductility. The presence of low melting phase saturated with impurities along the austenitic grain boundaries causes intergranular fracture at high temperature in C-Mn steels.     

Interaction between MoO3 and metals Te, Cd, Sb

Eighteen compositions of MoO₃-Te at 800 °C and seven of each of MoO₃-Cd (at 500 °C) and MoO₃-Sb (at 600 °C) were heat treated in vacuum-sealed quartz ampules. The phases of the heat-treated compositions were analyzed using x-ray diffraction (XRD) patterns. The interactions in the three systems are summarized. Three phases in equilibrium are (1) in the MnO₃-Te system at 800 °C, Te, Mo₄O₁₁, TeMo₄O₁₃—(0<x_{MoO 3}<0 889) and MoO₃, Mo₄O₁₁, TeMo₄O₁₃—(0.889<x_{MoO 3}<1); (2) in the MoO₃_Cd system at 500 °C, Cd, MoO₂, CdMoO₄—(0<x_{MoO 3}<0.6667) and MoO₃, MoO₂, CdMoO₄—(0.6667<x_{MoO 3}<1); and (3) in the MoO₃-Sb system at 600 °C, Sb, MoO₂, Sb₄Mo₁₀O₃₁—(0<x_{MoO 3}<0.734) and MoO₃+MoO₂+Sb₄Mo₁₀O₃₁ (0.734<x_{MoO 3}<1). The results lead to construction of ternary phase diagrams: Te-MoO₃-TeMo₄O₁₃, Cd-MoO₃-CdMoO₄, and Sb-MoO₃-Sb₄Mo₁₀O₃₁.     

Identification of Natural Products as Potential Pharmacological Chaperones for Protein Misfolding Diseases

Defective protein folding and accumulation of misfolded proteins is associated with neurodegenerative, cardiovascular, secretory, and metabolic disorders. Efforts are being made to identify small-molecule modulators or structural-correctors for conformationally destabilized proteins implicated in various protein aggregation diseases. Using a metastable-reporter-based primary screen, we evaluated pharmacological chaperone activity of a diverse class of natural products. We found that a flavonoid glycoside ( C-10 , chrysoeriol-7-O-β-D-glucopyranoside) stabilizes metastable proteins, prevents its aggregation, and remodels the oligomers into protease-sensitive species. Data was corroborated with additional secondary screen with disease-specific pathogenic protein. In vitro and cell-based experiments showed that C-10 inhibits α-synuclein aggregation which is implicated in synucleinopathies-related neurodegeneration. C-10 interferes in its structural transition into β-sheeted fibrils and mitigates α-synuclein aggregation-associated cytotoxic effects. Computational modeling suggests that C-10 binds to unique sites in α-synuclein which may interfere in its aggregation amplification. These findings open an avenue for comprehensive SAR development for flavonoid glycosides as pharmacological chaperones for metastable and aggregation-prone proteins implicated in protein conformational diseases.     

Nanostructured membranes and electrodes with sulfonic acid functionalized carbon nanotubes

Herein we report the covalent functionalization of multiwall carbon nanotubes by grafting sulfanilic acid and their dispersion into sulfonated poly(ether ether ketone). The nanocomposites were explored as an option for tuning the proton and electron conductivity, swelling, water and alcohol permeability aiming at nanostructured membranes and electrodes for application in alcohol or hydrogen fuel cells and other electrochemical devices. The nanocomposites were extensively characterized, by studying their physicochemical and electrochemical properties. They were processed as self-supporting films with high mechanical stability, proton conductivity of 4.47 × 10⁻² S cm⁻¹ at 30 °C and 16.8 × 10⁻² S cm⁻¹ at 80 °C and 100% humidity level, electron conductivity much higher than for the plain polymer. The methanol permeability could be reduced to 1/20, keeping water permeability at reasonable values. The ratio of bound water also increases with increasing content of sulfonated filler, helping in keeping water in the polymer in conditions of low external humidity level.     

Role of hydrogen in electrical and structural characteristics of bilayer CdTe/Mn diluted magnetic semiconductor thin films

Bilayer thin films of diluted magnetic semiconductor CdTe/Mn have been prepared using vacuum thermal evaporation method at pressure of 10⁻⁵ torr. Annealing of bilayer thin films has been performed in atmospheric condition at constant temperature 400 °C for 1 hour. Hydrogenation of as-grown and annealed bilayer thin films has been performed by keeping these in hydrogenation cell. Structural characteristics of as-grown and heat treated thin films have been performed by X-ray diffractometer. Current–voltage characteristics of both as-grown hydrogenated and annealed hydrogenated bilayer thin films have been studied to find out the effect of hydrogenation. Surface topography of as-grown and annealed bilayer thin films has been confirmed by optical microscopy.