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This article reviews state-of-the-art microdroplet technological solutions for screening microorganisms mutant and GMO strains. Microorganisms used in the production of various products – single-cell protein, single-cell oil, enzymes, pigments and other bioactive compounds – can always be improved and their properties enhanced to increase the production of products of interest, to simplify microbial cultivation process, improve efficiency or adapted strains to use cheaper raw materials such as agroindustrial by-products. Microorganisms can be improved using either classical mutagenesis techniques or genetic engineering methods. Regardless of the selected method for mutant or GMO creation, during the process most promising microorganism strains must be selected, which is usually a slow and labour-intensive process. The use of microdroplets is a promising technological solution to speed up strain selection. This review looks at the latest developments in microdroplet technology, compares their variations, and identifies future prospects.

The research and development of carotenoids production have a long history, and interest in this group of pigments has not decreased to this day. Among all existing carotenoids, six are considered industrially important: astaxanthin, β-carotene, lutein, zeaxanthin, canthaxanthin, and lycopene. These carotenoids have a wide range of application and are used as additives in food and beverage, feed, nutraceuticals, pharmaceuticals, and cosmetics due to their bioactive and colour properties. An undisputed leader in the global pigment market is chemically synthesized carotenoids. To a lesser extent, carotenoids derived from natural sources as plants and microorganisms. Currently, the market of natural carotenoids is mainly represented by microalgae Haematococcus pluvialis, Dunaliella salina, Botryococcus braunii, fungus Blakeslea trispora, yeast Phaffia rhodozyma and bacteria Paracoccus carotinifaciens. These microorganisms afford the production of astaxanthin, βcarotene, canthaxanthin, and lycopene. In turn, lutein is obtained by extracting marigold flowers Tagetes eracta L. and there is no other competitive source yet. Therefore, the potential of microorganisms to synthesize and accumulate lutein and other equally important carotenoids in their cells has been actively studied. Several yeast and bacteria species from Rhodosporidium, Rhodotorula, Sporobolomyces, Sphingomonas, Gordonia, and Sphingobacterium genus have a potential to replenish the diversity of sources of industrially important natural pigments, but available technologies still need improving. This paper reviews strategies for increasing of competitiveness of fungal and bacterial carotenoids production. Strategies such as selection of carotenogenic strain, use of low-cost substrates, simultaneous production of carotenoids and other value-added compounds, and optimization of fermentation medium and conditions are considered.

Biomethanation is a prospective method to integrate a renewable solar or wind power grid with a biogas grid, where excess energy can be used to produce hydrogen for the biomethanation of the biogas and produce biomethane. The use of biotrickling filter reactors with appropriate carrier materials for biomethanation is essential for the immobilisation of hydrogenotrophic methanogens on the surface of the packing material. Wood ash filter material use end-of-the-line waste ash as the main raw material for the production of filters. The wood ash filter material is a robust porous material that has good properties in the context of biomethanation. Testing packing materials in constantly operating biotrickling filter reactors would cost too much time and money. The purpose of this study is to compare a novel wood ash filter material with materials that are often applied in the sector. The study uses an effective methodology to test three alternative packing materials for use in a biotrickling filter. The manometric method and BMP test is used to determine the rate of CH4 production. The physical parameters such as bulk-specific surface area (m2 × m–3), external porosity (% vol), and bulk density (kg × m–3), and chemical composition of the novel wood ash filter material are compared to other filter materials commonly used in biomethanation applications. The results of the experiment determine whether the novel wood ash filter material or other tested materials can compete with and even replace some of the materials currently used in biomethanation applications.

X-ray diffraction method has been carried out to study the structure in the equiatomic InPbGaSnCu high entropy alloy in liquid state. Structure factors and pair correlation functions have been analyzed and used to determine the main structure parameters. Existence of shoulder on right hand side of principal peak and its transformation was the main feature of structure factors. Comparison of structure functions and main parameters obtained from them for multicomponent alloy with ones for constituent elements shown that mixing process is related with formation of structural inhomogeneities in liquid state.

A fragment of the Al corner in the ternary Al–Ge–Mg phase diagram has been constructed. Experimental methods have shown that the tie-line of the L ⇆ α-Al + Mg2Ge three-phase eutectic equilibrium (corresponding to the maximum temperature of eutectic transformation) does not match the stoichiometric Al–Mg2Ge section in the ternary Al–Ge–Mg phase diagram and is shifted toward its magnesium-rich side. The temperature–composition parameters of the univariant L ⇆ α-Al + Mg2Ge eutectic transformation and the boundaries of two-phase α-Al + Mg2Ge alloys after crystallization and annealing have been determined. The results will be used in the development of new aluminum casting alloys.

X-ray diffraction study of liquid and solid Al–Ge–Fe alloys along the sections Al-Fe33.3Ge66.7, Fe-Al65Ge35 и Ge-Al78Fe22 has been discussed. It has been shown that addition of third component to the corresponding binary melt leads to the atomic clusters with structure similar to liquid germanium due to energy inequality of interactions in Al–Fe and Fe–Ge pairs and competition between Al and Ge atoms in formation of local structure around Fe atoms in the ternary melts. The Al88Ge8Fe4, Al68Ge21Fe11, Al64Ge18Fe18, Al55Ge30Fe15 melts have been quenched by melt spinning technique. The fully amorphous state was obtained only for the Al55Ge30Fe15 ribbon, the one with composition Al68Ge21Fe11 is amorphous-crystalline and Al88Ge8Fe4 и Al64Ge18Fe18 ribbons are microcrystalline. A new hexagonal τ1 phase (a = 9.75(1) A, c = 8.80(1) A) in the ingot Al55Ge30Fe15 and Al41Ge39Fe20 alloys and a new tetragonal phase τ2 (a = 5.11(3) A, c = 4.60(2) A) in the ingot Al20Ge53Fe27 alloy have been found. The annealed at 623 K ribbons with composition Al88Ge8Fe4 and Al68Ge21Fe11 contain a new hexagonal phase τ3 (a = 6.709(5) A, c = 9.07(1) A), which is missing in the ingot.

The influence of the concentration of alloying components on thermal stability, magnetic and electrical properties of amorphous alloys of Co73-66Fe4,6-3Cr0-9(B,Si)22-29 system was studied by methods of differential scanning calorimetry, XRD, resistometry and magnetometry. The crystallization of several alloys with advanced magnetic characteristics was studied. At continuous heating of the ribbons, either primary or eutectic crystallization was observed depending on the chemical composition of these alloys. Certain tendencies in the anomalous behavior of temperature dependence of electrical resistance of ribbons were revealed. By increasing chromium and metalloids concentrations, we obtained the alloys with relatively low saturation induction and large difference between the Curie temperature and the temperature of crystallization onset. The heat treatment regimes to obtain the best magnetic properties of these alloys were found. Prospective applications of Co73-66Fe4,6-3Cr0-9(B,Si)22-29 amorphous ribbons for fabrication of high sensitive sensors of magnetic field were discussed.

The structure of Fe—P-Nb-Cr amorphous metallic glasses produced by a melt spinning technique was investigated. Using SAXS analysis the size distributions of inhomogeneities in the samples were determined in both as-quenched state and after heat treatment. The surface of amorphous Fe-B-P-Nb-Cr alloys in as-quenched state and after heat treatment at 620–750 K, depending on the alloy, was investigated. Unexpected surface phenomena were observed during SEM studies.

Several Fe-B-Si-P-Nb-Cr amorphous metallic glasses were produced by a melt spinning technique. The structure, thermal stability and crystallization processes of amorphous alloys were studied. The size distributions of inhomogeneities of both initial and annealed samples were determined.

The local atomic structure of the liquid Ni–Si and Al–Ni–Si alloys has been studied by X-ray diffraction and Reverse Monte Carlo simulations. The chemical short-range order and disordered close packing in the liquid binary and ternary alloys have been discussed. A method of calculating the X-ray scattering curve (I(Q)) of a ternary melt based on I(Q) of boundary binary melts was proposed and tested. The phase and microstructure analyses of the melt-spun and annealed Al70Ni10Si20 ribbons were performed.

X-ray diffraction study of the Al-Ge-Ni melts along different sections of the ternary phase diagram has been discussed. The measurements were taken at 1000 °C or at temperatures on 50° above liquidus for compositions with high melting point. It has been shown that Al Ni interactions play the most important role in the formation of the local atomic structure in the Al-Ge-Ni melts. The most significant decreasing of the nearest interatomic distance (R1) takes places with addition of Ni to binary Al Ge alloys. There is a competition between Al and Ge atoms in the formation of local atomic structure around Ni atoms. For ternary melts with high Ge content the influence of Ge Ge pairs increases resulting in the formation of the clusters with structure similar to the liquid germanium. The ribbons of the Al79Ge15Ni6, Al61Ge29Ni10 and Al61Ge15Ni24 alloys have been obtained by rapid solidification from the liquid state. The phase analysis of the as-quenched and annealed ribbons has been discussed.

The influence of winding-induced mechanical stresses on the magnetic anisotropy and core loss in toroidal cores made of Fe73Cu1Nb3Si16B7 ribbon is studied. The ribbon for the cores was rapidly pre-heated under tensile stress up to 120 MPa. It was found that magnetic characteristics of the material (magnetic anisotropy energy and the core loss) can be controlled by varying the tensile stress during the preliminary rapid heating of the ribbon. It was shown that with reducing core diameter, the magnetic anisotropy energy and core loss significantly increase. However, relatively high winding-induced core loss in small cores can be significantly reduced by increasing tensile stresses applied to the ribbon during pre-heating.

In this paper we present and discuss magnetic properties of the Al 87 Y 5 Ni 8 , Al 87 Y 4 Gd 1 Ni 8 , Al 87 Gd 5 Ni 8 , Al 87 Y 4 Gd 1 Ni 4 Fe 4 and Al 87 Gd 5 Ni 4 Fe 4 amorphous alloys. The examinations have been concentrated on a possible magnetic ordering at low temperatures and its modification by amorphous surroundings as well as different magnetic moment of alloying additions. It was shown that magnetic properties of the Al 87 Y 5 Ni 8 amorphous base alloy correspond to a superparamagnetic body with Ni magnetic clusters. Magnetic moment of Ni atom in amorphous aluminum matrix is found to be 0.3 μ B that corresponds to less than 50 Ni atoms per one cluster. Gd doping of the base alloy leads to a decrease of the resultant magnetic moment of Ni clusters that can be explained by some antiferromagnetic coupling Ni–Gd and Ni–Ni within magnetic clusters.

Crystallization of amorphous Al-based alloys (Al–Y–Gd–Ni–Fe) was investigated by applying differential scanning calorimetry (DSC), X-ray diffraction (XRD) and high resolution electron microscopy (HREM). It was shown that the crystallization in the examined alloys proceeds in three stages (DSC maxima). The two first stages are attributed to formation of solid solution of fcc Al(RE) nanograins in amorphous matrix. In the third stage the precipitation of ternary compound Al 19 Ni 5 RE 3 of the orthorhombic Al 19 Ni 5 Gd 3 -type structure was observed. A partial substitution of Ni by Fe causes a change of stoichiometry and crystal structure of the ternary compounds: Al 8 TM 4 RE (TM = Fe, Ni; RE = Y, Gd) of the tetragonal ThMn 12 (Al 8 Mn 4 Ce)-type structure. A partial replacing of Y atoms by Gd in the Al 87 Y 5 Ni 8 based alloy shifts the Al(RE) nanocrystallization to lower temperatures. In contrast to this a partial replacing of Ni by Fe shifts the nanocrystallization to higher temperatures.

Amorphous Fe73B7Si16Nb3Cu1 ribbon was crystallized rapidly by electric current heating under simultaneously applied tensile stress along the ribbon axis. As a result, strong transverse magnetic anisotropy was induced in the ribbon. Dynamic magnetic properties of the ribbons rapidly heated either under the tensile stress or without tensile stress were measured using toroidal cores. Optimal electric current heating regime that provides maximum improvement of the initial magnetic permeability and core loss was determined. Tensile stress increase from 0 to 180 MPa was shown to result in the decrease of the initial magnetic permeability down to 400 and core loss at frequencies from 0.4 to 200 kHz. Comparative analysis of magnetic properties of the cut core (with non-magnetic gap) and the cores heated under tensile stress was carried out. The magnetic properties of the latter cores are advantageous for manufacturing the reactors and linear chokes of switch-mode power supplies.

Corrosive properties of some Al-based amorphous metallic alloys (AMA) and the relationship between the AMA composition and nature of protective layers on the surface of alloys were studied. The complex of physico-chemical methods, namely the potentiometry, voltammetry, electrochemical impedance spectroscopy and electronic microscopy, has been used. It was shown that the influence of Dy doping on the same characteristics of alloys is opposite to that of Gd. It increases corrosion resistance of Dy-containing alloys in comparison to the reference Al87Y5Ni8 alloy. Partial substitution of 4 at. % Ni by Fe causes further increase of corrosion resistance of Al87Gd5Ni4Fe4.

The comparative analysis of magnetic properties of cut cores made of nanocrystalline Fe73Nb3Cu1B7Si16 alloy ribbon and cores made of the same ribbon with preliminary tension-induced transverse magnetic anisotropy was carried out. The possibility of improving magnetic properties of cut cores, decreasing loss, and increasing DC bias immunity of reversible magnetic permeability is presented. The influence of induced magnetic anisotropy on DC bias immunity of reversible magnetic permeability was investigated. The advantages and disadvantages of new cores (made of ribbon heated under tensile stress) over cut ones were determined.