Comparative Study on Reused Haemodialysis Membranes

In this paper the advantages of application of the nanocomposite track membranes (NCTM) with TiN coating as the substrates for sample preparation for their investigation by methods of electron microscopy are discussed. This membrane material was obtained by the ion-plasma sputtering of TiN coating on the polymer track-etched membrane. The physicochemical properties of NCTM were researched. Preparation technique allows to separate nanoand microdimensional samples from dry, liquid and gas mixtures for their investigation by methods of scanning and transmission electron microscopy.

Particulate growth processes in Ar+SiH4 RF plasmas are studied using ultraviolet light-absorption and scanning electron microscopic (SEM) methods. Measurements of particulate size and density using the SEM method show that they grow through three phases: nucleation, rapid growth and growth saturation. Such features of temporal evolutions of their size and density are very similar to those for He+SiH4 RF plasmas previously obtained by SEM and in situ laser light scattering methods. It is also found that particulates in two different size ranges coexist after the initiation of the rapid growth phase, and their coagulation plays an important role in this phase. Close similarities among spatial profiles of Si emission intensity, Si density, and amount of particulates are revealed in wide discharge-parameter ranges of 1–100% SiH4, 11–20 Pa, and 40–100 W. These results suggest that many short-lifetime neutral radicals such as SiHn (n=0–2) contribute to nucleation and subsequent initial growth of a particulate, since other short-lifetime radicals are also expected to have similar spatial profiles.

Methods of transmission and scanning electron microscopy and chemical microanalysis, electron diffraction, and X-ray diffraction were used to systematically study the structure and the chemical and phase composition of the Ni50Ti38Hf12 alloy synthesized by rapid quenching from the melt and subjected to various heat treatments. The critical temperatures of the devitrification of the initially amorphous rapidly quenched alloy and the B2 ↔ B19′ thermoelastic martensitic transformations have been determined. The lattice parameters of the B2 austenite and thermoelastic B19′ martensite have been measured. The main features of the formation of an ultrafine-grained structure in the alloy and the subsequent phase transformations (martensitic transformation and the decomposition with the formation of an intermetallic phase of the (Ti,Hf)2Ni type) have been studied depending on the regimes of heat treatment. Based on the results of measurements of mechanical properties upon tension (σM, σu, and δ) and the shape-memory effects (degree of shape recovery depending on the deformation by bending; and magnitude of the reversible strain erev), regimes for obtaining high-strength and plastic states of the alloy with a shape-memory effect have been established.

Methods of X-ray diffraction, transmission and scanning electron microscopy, and electron diffraction have been used to study phase and chemical compositions and structure of Ti2NiCu alloys. The alloys of the quasi-binary section TiNi–TiCu, which exhibit in the initial as-cast state thermoelastic martensitic transformations B2↔B19 and related shape memory effects, have been produced by rapid quenching of the melt (melt spinning technique). The chemical composition of the Ti2NiCu alloys was varied with respect to titanium and nickel within x ≤ ±1 at. %. The mechanical properties of the alloys have been measured in the initial state and after subsequent heat treatment. The kinetics of the crystallization from the amorphous state, devitrification processes and the forward and reverse thermoelastic martensitic transformations were investigated. Their characteristic temperatures have been determined by measuring temperature dependences of the electrical resistivity of the alloys. The diagram of the dependence of the critical temperatures on the chemical composition has been constructed.

Deep-sea Entoprocta from the Sea of Okhotsk and the adjacent open Pacific abyssal area: New species and new taxa of host animals

Young and mature larvae of queen and workers of the thief ant, Solenopsis helena, are herein described for the first time. Specimens were treated and described by usual methods of light and scanning electron microscopy. Many of the observed characteristics confirmed traits of the thief ant larva, reinforcing the assumption that they are a distinct group from fire ants. The larva of S. helena can be recognized from other close species by details of the mouthparts, but seem extensively similar to Solenopsis molesta. These findings are useful for taxonomic studies and phylogenetic inferences.

The South American species of the genus Viguiera (Asteraceae) have been transferred to Aldama based on molecular studies. However, the circumscription of Aldama tenuifolia and A. kunthiana has not been well established because the two species are morphologically similar. Both occur in areas of the Cerrado domain, especially in “campos sujos”, “campos limpos” and “campos rupestres”, which are characterised by intense solar irradiation, water scarcity during the autumn and winter, and frequent fires. The aim of the present study is to analyse the anatomy of the vegetative organs of both species in order to identify features that may be useful in their circumscription and in understanding their environmental adaptations. Samples of leaves, stems, xylopodia and roots of each species were collected, fixed, and processed according to the usual methods for light and scanning electron microscopy. The anatomical features useful to delimit the two species are the contours of the epidermal cell walls and in the occurrence of secretory ducts in the primary phloem and fundamental parenchyma of the midrib (leaves), the occurrence of secretory ducts in the primary and secondary phloem (stems) and the degree of cambial activity in the tuberisation process (roots). Regarding the environmental adaptation, both species share the presence of a xylopodium with a high bud shoot-forming potential, fructan accumulation in the tuberised roots, root-mycorrhizal associations, the occurrence of secretory structures, such as glandular trichomes (stems and leaves), internal secretory spaces (roots, xylopodia, stems and leaves) and hydathodes (leaves).

Quantitative analysis of the phase composition of the Ti – Al – Mo – V – Zr system is performed as applied to a standard titanium alloy VT20L. Polythermal and isothermal sections of the phase diagram are plotted, the solidus and liquidus temperatures and the temperature of transition to the β-range under heating (T pt) are determined. The methods of light and scanning electron microscopy are used to study the effect of heat treatment on the structure of alloy VT20L.

On the whole, 17 species of small-sized centric diatoms were revealed using the methods of light and scanning electron microscopy. Among them, five species (Aulacoseira subarctica, Cyclotella ocellata, Handmannia comta, Stephanodiscus minutulus, and Conticribra weissflogii) were found in water bodies of various urban agglomerations (Kiev and Zhitomir) for the first time. Their electron microphotographs, brief morphological description, and ecological and geographic characteristics are given in the paper. It has been found that the number of new species of Centrophyceae did not depend on the type of urban agglomeration. The presence of small-sized centric diatoms, and also of brackishwater species of the genus Thalassiosira Cl., in plankton of urban water bodies is one of the mechanisms of phytoplankton adaptation to anthropogenic load.

Individual sarcocysts were isolated from fresh or alcohol-fixed muscle samples of two moose from Alberta, Canada, and examined by light (LM) and scanning electron microscopy (SEM) and molecular methods, comprising polymerase chain reaction (PCR) amplification and sequencing of the complete18S rRNA gene and the partial cytochrome c oxidase subunit I gene (cox1). By LM, four sarcocyst types were recognized, and the sequencing results showed that each type represented a distinct species, i.e. Sarcocystis alces, Sarcocystis alceslatrans, Sarcocystis ovalis and Sarcocystis taeniata n. sp. The finding of S. alceslatrans and S. ovalis has been reported briefly previously, but further details are provided here, including the ultrastructure of sarcoysts of S. alceslatrans as seen by SEM. The species S. alces was found for the first time in Canadian moose, whereas the finding of S. taeniata is the first record of this species in any host. The sarcocysts of S. taeniata were sac-like and about 1,000-1,100 × 60-80 μm in size. By LM, the cysts had a thin and smooth wall with no visible protrusions, whereas SEM revealed that the cyst surface had sparsely but regularly distributed, thin ribbon-like protrusions, about 2 μm long and 0.2 μm wide, lying flat against the surface and leaving most of the cyst surface naked. Similar protrusions have previously been reported from Sarcocystis grueneri in reindeer, which was found by sequence comparisons and phylogenetic analyses to be the species most closely related to S. taeniata. The phylogenetic analyses further suggested that S. taeniata, like S. alces and S. alceslatrans, use canids as definitive hosts, whereas corvid birds are known definitive hosts for S. ovalis. In contrast to the three other species found, S. taeniata displayed considerable intra-specific and intra-isolate sequence variation (substitutions, insertions/deletions) in certain regions of the 18S rRNA gene.

TiNb coatings were obtained by the electro-explosive doping on the surface of a titanium dental implant (VT6 alloy). The elemental and phase composition was determined by the methods of scanning and transmission electron microscopy and by X-ray structural analysis. The morphology and defective substructure of the coating were studied. Hardness and Young's modulus, friction coefficient and wear resistance of the formed coating were determined. It has been established that the electro-explosive coating is multi-element and multi-phase and possesses submicro-and nanocrystalline structure, high strength and tribological properties. It was found, that the formation of TiNb coating is accompanied by a multiple (more than 2 times) decrease in the wear parameter, i.e. wear resistance increase of the surface layer, an increase in the friction coefficient by 1.5 times, significant increase in hardness (1.5 times) and Young's modulus (1.3 times).

The changes in the structure-phase state of the surface layer of molybdenum caused by the action of a soft-X-ray beam of energy density E<9 J/cm/sup 2/ and pulse duration 0.1 /spl mu/s were investigated by the methods of optical metallography, scanning and transmission electron microscopy. It has been found that the action of a soft X-ray beam causes the surface under irradiation to melt, produces thin films of complex-composition amorphous phases, and increases (almost doubles) the microhardness of the surface layer. The irradiation with soft X-rays has been demonstrated to be highly efficient method for enhancing the performance of materials and article. This method allows surface modification modes which, preserving the surface condition, preclude, in particular, crater formation, surface melting, etc.

The article considers laser alloying technologies of surface layers of samples made of structural steel using powder filler add-on materials based on tungsten carbide and chromium. Structural transformations, concentration changes of chemical elements, grain and subgrain structures, dislocation density, size and volume fraction of phase precipitates, causes of crack formation in treated surface layers under various alloying regimes have been studied by the methods of optical, analytical scanning, and transmission electron microscopy. It was found that the tendency to crack formation of samples after laser alloying is due to structural (crystallite size, shape factor) and concentration changes associated with redistribution of elements, in particular, chromium. Noticeable changes in the structural-phase state of the treated surfaces are observed for an optimal mode of laser alloying. This laser alloying regime is characterized by a uniform distribution of dislocations with a general decrease in their density. The sizes of phase precipitates in the surface layers are more dispersed and evenly distributed in the internal volumes of grains. These are nanoparticles with a size of 40...100 nm and larger phase precipitates (up to 1 μm).

The elemental and phase composition, the state of the defective substructure of eutectic silumin used for engineering were studied by the methods of scanning and transmission electron microscopy. The findings of the study show that silumin is a multiphase material and comprises, along with phases based on solid solutions of aluminum and silicon, intermetallic compounds of different composition. Particles of silicon and intermetallics have diverse forms and as a consequence they can both reinforce the material or cause microcracks in the process of product operation.

Intercalated polymer-silicate nanocomposites are obtained by the mechanochemical method from smectite clay, zeolite-containing roches, and polythiophene. Their structure and morphology are studied by the methods of scanning and transmission electron microscopy, as well as X-ray phase, thermal, and IR-spectroscopic analyses.