Production of antimicrobial nanofibers by electroforming

The possibility of electroforming nanofibers from a solution of polyvinyl alcohol containing an additive of a second polymer, polyvinylpyrrolidone, and the antimicrobial compound chlorhexidine digluconate was studied. The rheological and electrophysical properties of the solutions and their effect on the electroforming parameters were examined. The microbiological properties of the prepared nanofibers were characterized.     

Multipurpose geoinformation management system of Yenisei meridian territories

The paper presents the architecture and key functional characterisitcs of a multiservice geoinformation management system of Yenisei meridian territories. The system has original architecture that combines elements of classical GISs, information systems of satellite imagery storage, and decision support systems.     

Desorption of palladium and platinum from the VP-1P anionite

Complex forms of palladium and platinum forming in ammonia-nitrate solutions during the desorption of platinum group metals (PGM) from the VP-1P anionite are investigated. The possibility in principle of using VP-1P anionite for the removal of PGMs from electrolytes in the technology of silver refining is confirmed.     

Preparation of processible polyaniline-formate salt via emulsifier free inverted emulsion polymerization and its antistatic applications

For the first time, processible polyaniline salt was prepared by inverted emulsion polymerization pathway without using any emulsifier. Aniline oxidation with benzoyl peroxide, in the presence of formic acid, yields novel polyaniline-formate salt containing free formic acid (PANI salt), the latter being trapped due to agglomeration and the presence of cohesive forces between the acid molecules and polyaniline chains. The synthetic procedure, outlined above, constituted the basis for the preparation of PANI salt containing free formic acid. PANI salt was studied by complementary characterization methods: conductivity, FT-IR, XRD, XPS & TGA. PANI salt containing free formic acid turned out to be especially well suited for the fabrication of blends with poly(vinyl alcohol), showing a very low percolation threshold. This lowering of the percolation threshold was attributed to the plasticizing effect of polyvinyl alcohol molecules present in the polymer matrix.     

A technique for measuring permeability of samples of anisotropic rocks for water and gas

A technique, equipment, and software for measuring permeability (including anisotropic) of rock samples for water and gas, taking variations of density and dynamic viscosity of the flowing medium into account, is described. The proposed method is intended to determine permeability with a high accuracy (up to 3–5%) in a range of 10⁻²² to 10⁻¹⁵ m² at efficient pressures up to 50 MPa and temperatures up to 300°C. In the course of one experiment on a single sample, the developed equipment and technique ensure the simultaneous determination of the axial and radial permeability components of the sample for water and Klinkenberg’s parameter which characterizes a pore space of the rock.     

Enhanced Piezoelectric,Ferroelectric, and Electrostrictive Properties of Lead-Free (1-x)BCZT-(x)BCST Electroceramics with Energy Harvesting Capability

Next-generation electronics and energy technologies can now be developed as a result of the design, discovery, and development of novel, environmental friendly lead (Pb)-free ferroelectric materials with improved characteristics and performance. However, there have only been a few reports of such complex materials’ design with multi-phase interfacial chemistry, which can facilitate enhanced properties and performance. In this context, herein, novel lead-free piezoelectric materials (1-x)Ba_0.95Ca_0.05Ti_0.95Zr_0.05O₃-(x)Ba_0.95Ca_0.05Ti_0.95Sn_0.05O₃, are reported, which are represented as (1-x)BCZT-(x)BCST, with demonstrated excellent properties and energy harvesting performance. The (1-x)BCZT-(x)BCST materials are synthesized by high-temperature solid-state ceramic reaction method by varying x in the full range (x = 0.00–1.00). In-depth exploration research is performed on the structural, dielectric, ferroelectric, and electro-mechanical properties of (1-x)BCZT-(x)BCST ceramics. The formation of perovskite structure for all ceramics without the presence of any impurity phases is confirmed by X-ray diffraction (XRD) analyses, which also reveals that the Ca²⁺, Zr⁴⁺, and Sn⁴⁺ are well dispersed within the BaTiO₃ lattice. For all (1-x)BCZT-(x)BCST ceramics, thorough investigation of phase formation and phase-stability using XRD, Rietveld refinement, Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and temperature-dependent dielectric measurements provide conclusive evidence for the coexistence of orthorhombic + tetragonal (Amm2 + P4mm) phases at room temperature. The steady transition of Amm2 crystal symmetry to P4mm crystal symmetry with increasing x content is also demonstrated by Rietveld refinement data and related analyses. The phase transition temperatures, rhombohedral-orthorhombic (T_R-O), orthorhombic- tetragonal (T_O-T), and tetragonal-cubic (T_C), gradually shift toward lower temperature with increasing x content. For (1-x)BCZT-(x)BCST ceramics, significantly improved dielectric and ferroelectric properties are observed, including relatively high dielectric constant ε_r ≈ 1900–3300 (near room temperature), ε_r ≈ 8800–12 900 (near Curie temperature), dielectric loss, tan δ ≈ 0.01–0.02, remanent polarization P_r ≈ 9.4–14 µC cm⁻², coercive electric field E_c ≈ 2.5–3.6 kV cm⁻¹. Further, high electric field-induced strain S ≈ 0.12–0.175%, piezoelectric charge coefficient d₃₃ ≈ 296–360 pC N⁻¹, converse piezoelectric coefficient ${(d_{33}^{\ast })}_{\mathrm{ave}}$≈ 240–340 pm V⁻¹, planar electromechanical coupling coefficient k_p ≈ 0.34–0.45, and electrostrictive coefficient (Q₃₃)_avg ≈ 0.026–0.038 m⁴ C⁻² are attained. Output performance with respect to mechanical energy demonstrates that the (0.6)BCZT-(0.4)BCST composition (x = 0.4) displays better efficiency for generating electrical energy and, thus, the synthesized lead-free piezoelectric (1-x)BCZT-(x)BCST samples are suitable for energy harvesting applications. The results and analyses point to the outcome that the (1-x)BCZT-(x)BCST ceramics as a potentially strong contender within the family of Pb-free piezoelectric materials for future electronics and energy harvesting device technologies.     

Radiation-curable prepreg composites

Advanced composites, specifically carbon-fiber-reinforced epoxies, are used extensively for a variety of demanding structural applications, primarily because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, and damage tolerance characteristics. Electron beam (EB) treatment can be used to produce useful physical and/or chemical changes in plastics and composites by initiating various polymerization and crosslinking reactions. The advantages of using EB rather than thermal curing for carbon-fiber-reinforced epoxy composites include curing at ambient temperature, reduced curing times, and fewer volatiles. An EB-curable carbon fiber-acrylated epoxy composite is being developed for various applications. The tensile properties of the 14-ply EB-cured epoxy laminate were comparable with the properties of the thermally cured laminates used in the aircraft industry. Research is continuing to develop resin formulations and select coupling agents to improve the compression properties of EB-cured laminates.     

Transformation of Contact‐Explosives Primary Amines and Iodine(III) into a Successful Chemical Reaction under Solvent‐Free Ball Milling Conditions

Any synthetic transformation using contact‐explosives primary amines and hypervalent iodine(III) (phenyliodine diacetate) in constrained media (extreme conditions) is practically impossible. Herein, we report a method of controlling the explosion into a successful chemical reaction using the acid‐salt NaHSO₄. As a proof‐of‐concept, we considered mechanochemical (ball‐milling) cross dehydrogenative coupling (CDC) reaction for the amidation of aldehydes via C H activation. An isothermal titration calorimetric (ITC) study was helpful to understand the enthalpy changes during the reactions before and after addition of NaHSO₄.