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Abstract

The cellular organizations of intestine in Lepidocephalichthys guntea (Hamilton, 1822) have been described by light as well as scanning and transmission electron microscopy. The intestine is short and straight like, marked into anterior, middle and posterior region based on mucosal folds, number and size of columnar epithelial cells and mucous cells, thickness of submucosa and muscularis layer. The mucosa of anterior intestine forms high folds, which are lined with compactly arranged columnar epithelial cells and mucous cells. In the middle intestine, folds are pointless whereas the posterior intestine is without folds. The submucosa is formed of thin layer of connective tissue, contained collagen bundles and blood capillaries, comparatively well developed in the posterior intestine. By scanning electron microscopy, outlines of the luminal surface of anterior and middle intestine is embossed with oval or rounded columnar epithelial cells contained densely packed stubby microridges. The posterior intestine has closely set longitudinal folds characterized with minute blood capillaries and columnar epithelial cells having inconspicuous microridges. Ultrastructurally, the mucosal surface of the intestine consists of mucous cells with electron dense granules and columnar epithelial cells having numerous microvilli, mitochondria, endoplasmic reticulum, lysosomes and Golgi body. Cellular components of the anterior and middle intestine participate in the absorption whereas the presence of enormous blood vessels and capillary net work of posterior intestine probably responsible for air breathing.

Abstract

The structural characterization of the olfactory epithelium in Pygocentrus nattereri Kner, 1858 was studied with the help of light as well as scanning and transmission electron microscope. The oval shaped olfactory rosette consisted of 26–28 primary lamellae radiated from midline raphe. The olfactory epithelium of each lamella was well distributed by sensory and non-sensory epithelium. The sensory epithelium contained morphologically distinct ciliated and microvillous receptor cells, supporting cells and basal cells. The non-sensory epithelium was made up of labyrinth cells, mucous cells and stratified epithelial cells. According to TEM investigation elongated rod emerging out from dendrite end of the receptor cells in the free space. The dendrite process of microvillous receptor cells contained microvilli. The supporting cells had lobular nucleus with clearly seen electron dense nucleolus. The apex of the ciliated non-sensory cells was broad and provided with plenty of kinocilia. Basal cells provided with oval nucleus and contained small number of secretory granules. The mucous cells were restricted to the non-sensory areas and the nuclei situated basally and filled with about two-third of the vesicles. The functional significance of various cells lining the olfactory epithelium was discussed with mode of life and living of fish concerned.

Abstract

The morphoanatomy, cellular organization, and surface architecture of the olfactory apparatus in Cirrhinus reba (Hamilton) is described using light and scanning electron microscopy. The oval shaped olfactory rosette contained 32 ± 2 primary lamellae on each side of the median raphe, and was lodged on the floor of the olfactory chamber. The olfactory lamellae were basically flat and compactly arranged in the rosette. The olfactory chamber communicated to the outside aquatic environment through inlet and outlet apertures with a conspicuous nasal flap in between. The mid dorsal portion of the olfactory lamellae was characterized by a linguiform process. Sensory and non-sensory regions were distributed separately on each lamella. The sensory epithelium occupied the apical part including the linguiform process, whereas the resting part of the lamella was covered with non-sensory epithelium. The sensory epithelium comprised both ciliated and microvillous receptor cells distinguished by the architecture on their apical part. The non-sensory epithelium possessed mucous cells, labyrinth cells, and stratified epithelial cells with distinctive microridges. The functional importance of the different cells lining the olfactory mucosa was correlated with the ecological habits of the fish examined.

Abstract

In the present study, the fine surface structures of Cystocaulus ocreatus and its worm as well as brood nodules obtained from the lung of Akkaraman sheep are demonstrated by scanning electron and light microscopy. The mouth of the parasite obtained from the worm nodules is located at the anterior tip and encircled by a collar of tissue. The mouth opening appears as three slits conjoined in the shape of a capital case letter Y, creating three lips. The mouth is surrounded by six papillae just behind the collar. The anterior end was similar in both sexes and covered by numerous wrinkles. Female parasite has a bell-shaped pro-vagina. The posterior end of the female parasite was sharply pointed. The male parasite has a bursa. In the worm nodule, curled parasites were enclosed by a capsula and no eggs and larvae of the parasite were observed. In the brood nodule, heavily affected alveoli and bronchioles contained excessive amounts of larvae and eggs.

Abstract

This paper presents first results and test of passive detection of Digisonde signal obtained at the Průhonice station, Czech Republic. Described technique can be used to analyze signals transmitted by the Digisonde and further received by simple loop antenna. The receiving system is based on the software defined radio (SDR USRP N210). The device works as the two channels receiver. This method will be employed to record oblique ionograms at several locations in the Czech Republic forming a simple array for detection of fine structures within ionospheric plasma using common DPS 4D transmitter. Using relatively inexpensive passive detection helps to increase a number of reflection points which leads to a better spatial coverage of the ionosphere sounding. The device represents a complementary measurement for detection of signal transmitted by Digisondes in European sector.

Abstract

The fine structure of the buccal capsule of the adult female nematode Anguillicoloides crassus (Spirurina) was studied for the first time. Results are based on serial section (longitudinal and transverse) light and transmission electron microscopy. The buccal capsule of A. crassus is a cuticular-lined structure. It can be divided into three main parts: cheilostom, gymnostom and stegostom. The cheilostom is the anterior region of the buccal capsule with the cuticular lining continuous with the body wall cuticle and underlain by epidermal syncytia. The gymnostom is a cuticular region with portions of it very electron dense and underlain by arcade syncytia. A dense circumoral cylinder together with the circumpharyngeal ring represent the prominent characters of the gymnostom. The stegostom is formed by anterior pharyngeal cuticle underlain by muscular radial cells and epithelial marginal cells. The cephalic cuticle of A. crassus makes a direct contact with the pharyngeal cuticle at the base of the circumoral cylinder, within a circumpharyngeal ring containing projections of pharyngeal muscular and marginal cells. The circumoral cylinder, circumpharyngeal ring and pharynx are connected to the body epidermis by junctional complexes. The buccal capsule includes occasionally 3 projections of the pharynx evidently observed in serial cross sections. These ultrastructural characters may provide useful data for comparative, functional as well as evolutionary studies within the Chromadorea.

Abstract

Soft X-ray imaging is a very useful diagnostic technique in plasma-focus (PF) experiments. This paper reports results of four experimental sessions which were carried out at the DPF-1000U plasma-focus facility in 2013 and 2014. Over 200 discharges were performed at various experimental conditions. Measurements were taken using two X-ray pinhole cameras with a line of sight perpendicular to the z-axis, at different azimuthal angles (about 20° and 200°), and looking towards the centre of the PF-pinch column. They were equipped with diaphragms 1000 μm or 200–300 μm in diameter and coated with filters of 500 μm Al foil and 10 μm Be foil, respectively. Data on the neutron emission were collected with silver activation counters. For time-resolved measurements the use was made of four PIN diodes equipped with various filters and oriented towards the centre of the PF-column, in the direction perpendicular to the electrode axis. The recorded X-ray images revealed that when the additional gas-puff system is activated during the discharge, the stability of the discharge is improved. The data collected in these experiments confirmed the appearance of a filamentary fine structure in the PF discharges. In the past years the formation of such filaments was observed in many Z-pinch type experiments. Some of the recorded X-ray images have also revealed the appearance of the so-called hot-spots, i.e. small plasma regions of a very intense X-ray emission. Such a phenomenon was observed before in many PF experiments, e.g. in the MAJA-PF device, but it has not been investigated so far in a large facility such as the DPF-1000U. The time-resolved measurements provided the evidence of a time lapse between the X-ray emission from plasma regions located at different distance from the anode surface. The formation of distinct ‘hot-spots’ in different instants of the DPF-1000U discharge was also observed.

Synchrotron microanalytical methods in the study of trace and minor elements in apatite

Synchrotron X-ray facilities have the capability for numerous microanalytical methods with spatial resolutions in the micron to submicron range and sensitivities as low as ppm to ppb. These capabilities are the result of a high X-ray brilliance (many orders of magnitude greater than standard tube and rotating anode sources); a continuous, or white, spectrum through the hard X-ray region; high degrees of X-ray columniation and polarization; and new developments in X-ray focusing methods. The high photon flux and pulsed nature of the source also allow for rapid data collection and high temporal resolution in certain experiments. Of particular interest to geoscientists are X-ray fluorescence microprobes which allow for numerous analytical techniques including X-ray fluorescence (XRF) analysis of trace element concentrations and distributions; X-ray absorption spectroscopy (XAS) for chemical speciation, structural and oxidation state information; X-ray diffraction (XRD) for phase identification; and fluorescence microtomography (CMT) for mapping the internal structure of porous or composite materials as well as elemental distributions (Newville et al. 1999; Sutton et al. 2002; Sutton et al. 2004).

We have employed several synchrotron based microanalytical methods including XRF, microEXAFS (Extended X-ray Absorption Fine Structure), microXANES (X-ray Absorption Near Edge Structure) and CMT for the study of minor and trace elements in apatite (and other minerals). We have also been conducting time resolved X-ray diffraction to study nucleation of and phase transformations among precursor phases in the formation of apatite from solution at earth surface conditions. Summaries of these studies are given to exemplify the capabilities of synchrotron microanalytical techniques.

Summary

Spermatological characteristics of Calicotyle affinis Scott, 1911, an endoparasitic monocotylid monogenean from the cloaca of a holocephalan fish Chimaera monstrosa L, have been investigated by means of transmission electron microscopy for the first time. Spermiogenesis exhibits features basically similar to those of the congeneric Calicotyle kroyeri and Calicotyle australiensis, but there are some new findings with respect to the formation and fine structure of the spermatozoon including the remarkable complex end-piece (EP). Morphogenesis of the EP, which is located at the anterior (proximal) region of the late spermatid, includes two stages: (1) the centriolar region is continuous with a cytoplasmic mass of the zone of differentiation, the electron-dense surface of the spermatid undergoes significant changes in the sculpturing and the inner core of developing spermatid is electron-lucent; (2) after central fusion of the arching membranes a definitive structure of the EP is subsequently evolved, finally comprising 3 – 4 electron-dense discs attached to a central common electron-lucent column. The EP is considered as a synapomorphy of the genera Calicotyle + Dictyocotyle. The mature spermatozoon of C. affinis comprises the EP, two parallel axonemes of almost equal lengths with the 9 + “1” trepaxonematan pattern, mitochondrion, nucleus, and a reduced number of parallel cortical microtubules (1 – 3). The posterior (distal) extremity of the mature spematozoon contains a single tapering axoneme. Ultrastructural characteristics of the mature spermatozoon of C. affinis coincide mostly with those of congeneric C. australiensis. Variations of the spermatological characters within the genus Calicotyle, between Calicotyle and enigmatic Dictyocotyle as well as other monocotylid monogeneans are discussed.

Abstract

In this work was established that serial traditional hardfacing materials based on the Fe-Cr-C system are not effective for improvement of abrasion resistance of elements of equipment for production of bricks, solid fuel briquettes and for restoration of augers, due to the fact that this equipment works at significant specific and cyclic loads. Features of the coarse-grained structure of Fe-Cr-C based coatings leads to intensive abrasive wear. The aim of this study was to increase a durability of that equipment by using of flux cored electrodes with reaction components of Ti, Cr, Mo, B4C and their combinations to provide synthesis, which leads to fine-grained structure of refractory borides and carbides and their solid solutions with increased hardness. Structure of the hardfacing coatings were investigated by method of metallography, scanning electron microscopy (SEM), electron backscatter diffraction (BSD) mode and energy dispersive X-ray spectroscopy (EDS). Temperature dependences of equilibrium phase amount of the hardfacing materials were calculated by the CALPHAD technique, using JMatPro software. It was investigated that the offered materials are characterized by higher wear resistance at high specific and cyclic loads in comparison with serial production high-chromium hardfacing materials (Lastek, ESAB, Paton IEW). It was established that the abrasion wear resistance at high specific and cyclic loads depends mostly of formation of the structure of hardfacing material, and not the hardness. Also, using of powders of pure metals and their combination as reaction mixture for FCAW leads to fine structure which contains of refractory borides and carbides and their solid solutions.