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Our recent results on application of 4D laser printing to preparation of porous core-shell polymer structures containing encapsulated micro and nanoparticles are overviewed. Thus prepared polymer-matrix nanocomposite can find their application in micro/nano-electromechanical systems. Synthesized highly porous nanocomposites can also be used in catalysis, lab-on-chips, hydrogen storage devices, surgery medicine, and drug delivery systems.

–The gas-sensing properties of nickel ferrite (NiFe2O4) and nickel oxide (NiO) nanoparticles prepared by a self-sustaining levitation-jet synthesis (LJS) method are reported. These have been compared to the gas-sensing properties of a NiO sensor prepared using a commercially sourced powder. The microstructure, surface area, particle size, and morphology varied widely across the sensors fabricated. It was anticipated that these contrasting properties would play a key role in either enhancing or worsening the sensing capabilities of the materials. Gases of interest included ethanol, toluene, and carbon monoxide as well as the gas response of the sensors was investigated at different operating temperatures. In general, the sensors responded to gases with different degrees of sensitivity. Among the sensors with higher surface areas, one provided noticeable enhancements in sensitivity towards gases when compared, for instance, to the sensitivity of the commercially based NiO sensor. The NiFe2O4 sensor presented most promise as a gas sensor to ethanol and, to a greater or lesser degree, towards toluene gas. In general, sensors were poorly responsive to the carbon monoxide concentrations tested. This study is one of the first reports of using LJS-based powders for gas sensing applications and it highlights the suitability of the method to fabricate size- and shape-controlled nanomaterials for the detection of environmentally relevant gases.

For the first time, complex oxide NaFeYO7 + x was prepared by SHS (T c = 750–1200 K, U = 1–4 mm/s) in the Na-Fe-Y-O system. Explored was the influence of reagents ratio on combustion limits for the mixtures under study. Combustion products were characterized by XRD, SEM, EDX, chemical analysis, and magnetic measurements. Single-phase NaFeYO7 + x was obtained at an excess of sodium in green mixtures. To stabilize the product, the water-washing procedure was used just after synthesis. The synthesized material has a cubic crystal structure with a cell parameter close to that of sodium yttrate NaYO2, it exhibited very weak magnetic properties, and overly-stoichiometric oxygen content. The product is heat resistant up to 450 K. The synthesized product is a new inorganic superoxide with good technological perspectives for use as a solid oxygen-containing material.

Selective laser sintering (SLS) process was used to prepare nanostructured porous 3D items consisting of Ni or/and Cu nanoclusters embedded into a polycarbonate (PC) matrix for potential use in nanoelectromechanical systems (NEMS). Liquid-phase SLS was performed (in air or Ar) with the Ni-PC powder mixtures taken in proportions of 1 : 1, 1 : 2 (Ni particle size 27–184 nm) and Cu-PC powder mixtures (1 : 9, 1 : 4, 3 : 7, Cu particle size 76–90 nm) using a cw YAG : Nd+3 laser (P = 4–10 W) and a scanned spot of slightly defocused beam. After sintering, the size of starting nanoparticles remained unaffected. Demonstrated was the feasibility of SLS production of functionally graded 3D items, which opens up a way to direct synthesis of NEMS devices. Process conditions for preparation of monolayers and 3D items were optimized. Functionally graded 3D items with alternating ferromagnetic Ni-PC and non-magnetic Cu-PC layers exhibited interesting electrophysical and magnetic properties.

The effect of a 0.2 T external magnetic field on the heterogeneous combustion of a mixture of iron metal and oxide (Fe2O3) system with solid oxidizer (NaClO4) was studied. Time-resolved X-ray diffraction (TRXRD) was used to study the kinetics of intermediate product formation and thermal imaging experiments to measure the reaction temperature and velocity. Metastable fcc iron phase formation was discovered as an intermediate predominantly in applied field reactions.

Overviewed are new experimental methods for investigating the processes of phase formation during SHS. The first experiments using penetrating synchrotron radiation and energy dispersive detectors for different classes of complex inorganic materials were carried out in ESRF (Grenoble, France), LURE (Orsay, France) and Daresbury (UK). A new and very sensitive thermal imaging method (Thermal Imaging Technique, TIT) is based on continuous registration of the whole combustion process by using a highly sensitive IR camera and software developed by MIKRON Instruments Co. (USA) was also used for precise registration of combustion parameters. SHS was performed on different types of pure on doped complex inorganic materials in pellet and powder form in a range of dc magnetic field induction up to 20 T and electrical field strength up to ±220 kV/m. The dc magnetic field was applied during the reaction, supplied either by permanent magnet (transverse, 1.1 T) or by an electromagnet (longitudinal, up to 20 T). The dc electrical field was applied along direction of the combustion wave propagation. The combined processes of SHS and SLS (Selective Laser Sintering) of 3D articles for different powdered compositions was realized with optimal parameters of laser irradiation, under what SHS reactions proceeded in controlled regime.

The comparative microstructural analyses and histomorphological studies of tissue reactions to porous titanium and nitinol implants synthesized by Selective Laser Sintering (SLS) are presented for a rat model for bone implants. It was discovered that the surface of porous pegs of titanium and nitinol made by SHS/SLS has a significantly favorable structure to the mechanical interlocking with bone and soft tissues. Histological analysis of decalcified paraffin sections after implant removal could only show that trabecular bone structures and marrow cavities were observed around the porous implants. In the connective tissue of the remaining implant beds the following cells: macrophages, fibroblasts, adipocytes and lymphocytes are discernible. It was shown that the nitinol synthesized by combined SHS/SLS technique has a developed and ordered microstructure.

A new approach to power engineering modeling in a weak electrically conductive dynamic medium with induction fields was developed. The optimum induction field energy for moving liquid-gas systems in which chemical transformations takes place was estimated. For these systems, the dynamics of Joule energy dissipation and pondermotive action distributions was found to depend on the induction field frequency and movement velocity.

We suggest two approaches to collecting the electromotive force (Ec) generated by SHS reactions such as the use of mechanical systems with a movable voltage-collecting electrode and the so-called battery assembly. The use of the battery system comprising of two reactive systems generating voltage of opposite polarity afforded to increase Ec up to 2.3 V.