Study of flexographic imprints using the methods of optical and electron microscopy

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.

The methods of optical and electron microscopy and microanalysis are the linchpin of forensic inorganic analysis. However, their capacity is limited as for the exact identification of pigments and colour layers, and therefore it is essential that they be complemented by other methods of phase microanalysis - powder X-ray microdiffraction (micro pXRD) and FTIR in transmission mode. The classic way of sample division for different methods is not suitable with regard to the inhomogeneity of the sequence of strata. That is why a method was tested that would allow performance of optical microscopy, SEM/EDS(WDS), micro pXRD and FTIR in a nondestructive manner, from an identical spot of a single fragment. The solution can be polished sections - embedded samples and microtome sections. Conductive zerobackground single-crystal silicon plates were developed and tested for sample fixation in SEM, micro pXRD and transmission FTIR. Methods using a focused ion beam - FIB have recently gained importance in the field of electron microscopy. In the forensic sphere they can be employed in examinations of metal materials, technical analyses of documents, post-blast and gunshot residues.

To date, there is a large body of information on the structural composition of oocytes and embryonic cells of mammals, embryonal nucleogenesis, processes of gene expression, and specific protein synthesis during the preimplantation period. Different factors playing the key role in the transformation of the oocyte to the embryo after in the fertilization and activation of the embryonic genome [1–3] have been revealed. The number of such factors, revealed, as a rule, in the oocyte cytoplasm, constantly increases. In numerous studies on nucleus transplantation it was convincingly shown that oocytes contain specific factors causing genes highly specialized somatic cells to behave as the embryonic genome. It was established that these changes in gene expression are accompanied by considerable structural rearrangement of nuclei of these cells and their chromosome material [4–6]. As a result, the nuclei acquire the potential to direct and support embryonic development to term, though with an extremely low probability. The ability of mature oocytes to induce epigenetic reprogramming of nuclei and transform highly specialized cells ito stem cells is unique. Paradoxically, oocytes become unable to support these processes immediately after fertilization [6, 7]. Currently, the topical studies on derivation of embryonic stem cells from reconstructed embryos for therapeutic use challenge the problem of determination of the main strategy of cell reprogramming It is necessary to know in detail the spatiotemporal pattern of structural and functional rearrangements in donor nuclei and in reconstructed embryos to elucidate the mechanisms underlying these processes, and their influence on further embryo development. Among different methods of cell studies, the optical and electron microscopy are most adequate to provide a clear picture of localization of nuclei and chromatin structure and detect even very small changes in cells. Preparation of serial sections with subsequent three-dimensional reconstruction of objects on the basis of electron microscopy is a very useful approach to studying the rearrangements of nuclei in somatic cells being transferred into oocytes. No studies of this kind have been performed thus far. In this study, we obtained mouse embryos with the genome of cumulus cells and examined rearrangements in cumulus cell nuclei at early stages of their remodelling in the oocyte cytoplasm using serial ultrathin sections and three-dimensional reconstruction.

During its existence, electron microscopy has become one of the reference methods for assessing the structural and functional state of cells, tissues and organs, and an extensive evidence base has been formed that allows its use in the creation and formation of a biobank. The selection of sources for the literature review was carried out using keywords based on publications over the past 20 years. The publications presented in the review were selected by searching the eLIBRARY.RU, PubMed and Scopus databases. Based on foreign and domestic experience in the work of biobanks, we can distinguish four areas that determine the effectiveness of the use of electron microscopy studies as a component of its work. Firstly, it is control of microbiological contamination of a biological sample. The effectiveness of electron microscopy in detecting contamination of a biological sample with bacteria, fungi and viruses is comparable to the effectiveness of classical microbiological techniques. Secondly, it is a diagnostic tool that allows you to identify or confirm the presence in a sample of a pathogenetic process that is of interest for biobanking: tumor growth, atherosclerotic vessel damage, etc. Thirdly, it is quality control for cryopreservation of samples. A wide range of morphological characteristics of the ultramicroscopic structure of cells and microanatomical formations makes it possible to characterize the quality of cryopreservation and quantify the degree of damage, which contributes to the unification and standardization of biobanking. Transmission electron microscopy is the most informative in this matter. Fourthly, this is the basis for digitalization of the results obtained and the formation of an interdisciplinary biobank repository, which allows the use of “big date” technologies for fundamental research. The compliance of the biobank profile with the economic, scientific and industrial characteristics of the infrastructure of the industry or region is of great importance. Electron microscopy data are successfully combined with the results of molecular studies, which allows the formation of interdisciplinary metadata databases suitable for interregional and interdisciplinary scientific integrations. The latter makes it possible to use electron microscopy data to solve a wide range of applied and interdisciplinary problems. The above allows us to consider scanning and transmission microscopy methods as one of the key methods in the development of biobanking in the region.

Application of microarray technology for microbial diagnosis in stem cell cultures: a review

With the aid of the methods of photometry and electronic microscopy, we studied the sedimentation and aggregative stability of the lipid­magnetite suspensions (LMS). Different LMS were obtained. All suspensions are sufficiently stable over time. The best results in stability were displayed by suspensions, in which the ratio Fe 3 O 4 :SAS=0,02:0,35 g or 0,04 mass %:0,70 mass % and 0,025:0,35 g or 0,05 mass %:0,70 mass %. We determined size of the particles of magnetite with SAS. The order of mean particle size is defined – it amounts to ~76 nm. It was found that in the course of time (0–48,0 h) and with an increase in the wavelength (210–1000 nm), a gradual increase in the coefficient of transmission is observed from 25 % (210 nm) to 71,9 % (1000 nm) at 0 hours of exposure of the suspension: from 27,5 % (210 nm) to 81,2 % (1000 nm) at the maximum period of exposure of the suspension (48 hours). The indices of LMS are determined: concentration of the particles – N=1,43 1012 сm ­3 , in 48 hours the concentration decreased by 20 % (N=1,19·1012 сm ­3 ); r=38 nm, n=1,48, k=0,01. The distribution function of the particles by size is rather narrow and symmetrical, which indicates that the system of the synthesized nanoparticles is homogenous with a low degree of polydispersity. The UV spectra of LMS and their components were taken and analyzed. The comparison of the spectra of transmission of suspensions with different degree of dilution testifies to chemical identity of the samples. The kinetic dependences of the coefficient of transmission for the suspensions with different concentration of magnetite (Fe(ov.).), were examined, based on which we calculated the effective mean radius of the particles of the stabilized magnetite: 76–168 nm. The mean radius of the particles in the lipid suspension of magnetite without stabilizer (r eff )=400 nm. Visually, LMS manifested high aggregation stability at the total time of sedimentation reaching several tens of hours. It was established that LMS can be used as the biologically­active and food supplements, which possess the comprehensive action: beneficial biological effect on the human organism; due to the presence of bivalent iron in magnetite and capacity to form transition complexes with oxygen and peroxide radicals (and hydroperoxides), they manifest antioxidant activity, which leads to improvement in the quality and lengthening of the period of storage of the products that contain fat. Furthermore, LMS due to Fe 2+ of magnetite can be recommended as the source of easily assimilated iron and as the anti­anemic means. Therefore, the introduction of LMS to the food products increases its quality, nutritional and biological value.

Chapter 3 - Characterization of nanoparticles

Aminoglutethimide ( Elipten, Ciba,) interferes with the biosynthesis of adrenocortical hormones by blocking the conversion of cholesterol to pregnenolone. Male albino rats were fed with the diet containing aminoglutethimide and were killed after various time intervals ranging from 24 hours to 7 days. The adrenal cortices of these animals were studied both by light and electron microscopy. Special effort was made to determine the intracellular localization of free cholesterol by an electron microscopic histochemical method using the digitonin reaction. The animals killed 24 hours after the initiation of the feeding were found to have small myelin figures in contact with the mitochondrial membrane in fasciculata cells which might reflect compensatory rise of ACTH. The animals fed with the diet for 4 to 7 days were shown to have enlarged adrenal cortex. Light microscopic examination revealed an increase of the lipid globules both in size and number in the zona fasciculata. Ultrastructural studies showed swollen, hypertrophied, bizarre prophiles of the mitochondria with the formation of the vacuoles. The electron microscopic histochemical method demonstrated digitonincholesterol crystals localized in the vacuoles of the mitochondria, in the perimitochondrial areas and in the lipid globules. These findings correlate well with the biochemical data which indicate the intracellular site of steroid bicsynthesis and lend morphological support to the view that the biosynthesis of pregnenolone from cholesterol takes place within the mitochondria. These results indicate that aminoglutethimide causes accumulation of cholesterol in the vacuoles of the mitochondria.

As obligate intracellular parasites, viruses need to hijack their cellular hosts and reprogram their machineries in order to replicate their genomes and produce new virions. For the direct visualization of the different steps of a viral life cycle (attachment, entry, replication, assembly and egress) electron microscopy (EM) methods are extremely helpful. While conventional EM has given important information about virus-host cell interactions, the development of three-dimensional EM (3D-EM) approaches provides unprecedented insights into how viruses remodel the intracellular architecture of the host cell. During the last years several 3D-EM methods have been developed. Here we will provide a description of the main approaches and examples of innovative applications.

Vacuum systems in electron microscopy, by Wilbur C. Bigelow. vol. 15 in “practical methods in electron microscopy,” A. M. glauert, ed., portland press, London, 1994, 492 pp., $80 (paperback), $175 (hardcover)

9. Electron Microscopy

High-strength, wear-resistant steel often suffers from delayed cracking after flame cutting. Delayed cracking can lead to extremely harmful sudden brittle fracture; therefore, it is necessary to study the formation of delayed cracking in high-strength steel. This work investigated the influence of TiN inclusions and segregation on the delayed cracking in NM450 wear-resistant steel by optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and electron backscattered diffractometer methods. The results indicated that the delayed cracks originated from the segregation zones (SZs) containing multiple high-hardness segregation bands. The tensile strength of the SZ specimens was higher than that of non-segregation zone (NSZ) specimens, while the total elongation and reduction of area of the SZ specimens were relatively lower compared with the NSZ specimens. Therefore, the delayed cracking on the flame cutting surface of the NM450 steel plate was attributed to the existence of SZs that contain a high density of dislocations and considerable micro-sized TiN inclusions.

Fabrication of nanocrystalline austenitic stainless steel with superior strength and ductility via binder assisted extrusion method

After running 41808 hours, the superheater tube of a medium temperature separated circulating fluidized bed boiler in a plant cracked. The tube is swollen and thick-lip-shape fracture is covered with oxides. By utilizing energy dispersive spectrometer(EDS), transmission electron microscopy(TEM), optical microscopy(OM), scanning electron microscopy(SEM), ANSYS, and other methods to detect the tube, it is found that the element content of the tube conforms to the standard. In terms of the shape of the fracture morphology, it is transcrystalline rupture, along with dimple and pores in the grain boundary. The carbides gather and grow at the grain boundaries, and the morphology of tempered sorbite is not obvious. By thermal field and stress analysis, the tube stressed runs in super-temperature environment. The tensile strength of the failed tube is not up to the standard. In all, the failure reason of superheater tube is high temperature creep cracking which is caused by the tube is not up to the T91 steel standard and long-term overheating resulted from the oxide layer.

Poor manganese ore dressing on the basis of mineralogical-technological studies