Understanding the dielectric properties and electromagnetic shielding efficiency of zirconia filled epoxy-MWCNT composites

In the present study, hybrid composites are prepared by reinforcing various concentrations of high permittivity zirconia nanofiller into epoxy/CNT compositions to test their usability in EMI shielding applications in the X and Ku bands. ZrO2 nanofiller is added in different proportions to improve absorbance shielding while maintaining the composite conductivity uniform by adding constant CNT concentration to restrict the reflectance shielding. The microscopic studies have revealed an efficient dispersion of ZrO2 nanoparticles in the CNT networks and provided a smoother surface. The presence of zirconia nanofillers increased the dielectric properties, viz. the dielectric constant (194 at 0.1 Hz) and loss tangent (1.57 at 0.1 Hz), respectively, whereas the conductivity was found to be invariantly constant. The increased permittivity of composites enhanced the shielding by absorption, while the shielding by reflection is least influenced by the addition of zirconia nanofiller. The addition of zirconia nanofillers increased the permittivity and tan delta, allowing charges to accumulate at the interfacial areas for incoming EM radiations, resulting in increased absorbance shielding. Limiting the CNT concentration in all composites to the same level resulted in the formation of conductive networks, thus resulting in uniform reflectance shielding for all the hybrid composites in the present study. The dynamic mechanical analysis showed the improvement in the storage modulus and activation energy due to the enhanced interfacial adhesion and cross-linked polymer density.

Tongue Leptin Decreases Oro-Sensory Perception of Dietary Fatty Acids

Leptin, an anorectic hormone, regulates food intake, energy expenditure and body weight. We assessed the implication of tongue leptin in the modulation of oro-sensory detection of dietary fatty acids in mice. The RT-PCR analysis showed that mRNA encoding leptin and leptin receptor (Ob-Rb) was expressed in mice taste bud cells (TBC). Confocal microscopic studies showed that the lipid sensor CD36 was co-expressed with leptin in mice TBC. Silencing of leptin or Ob-Rb mRNA in tongue papillae upregulated preference for a long-chain fatty acid (LCFA), i.e., linoleic acid (LA), in a two-bottle paradigm in mice. Furthermore, tongue leptin application decreased the preference for the LCFA. These results suggest that tongue leptin exerts an inhibitory action on fatty acid preference. In isolated mice TBC, leptin decreased LCFA-induced increases in free intracellular calcium concentrations, [Ca2+]i. Leptin and LCFA induced the phosphorylation of ERK1/2 and STAT-3 and there were no additive or opposite effects of the two agents on the degree of phosphorylation. However, leptin, but not the LCFA, induced phosphoinositide-3-kinase (PI-3-K)-dependent Akt phosphorylation in TBC. Furthermore, leptin induced hyperpolarization, whereas LCFA induced depolarization in TBC. Our study demonstrates that tongue leptin exerts an inhibitory action on oro-sensory detection of a dietary fatty acid by interfering with Ca2+ signaling and membrane potential in mice TBC.

Diagenetic stages of oil-saturated sandstones of the pashyisky horizon at the Romashkinskoye oil field

It was identified three stages of reservoir rock formation of the Pashyisky horizon of the Frasnian stage of the Upper Devonian at the Romashkinskoye field, based on optical microscopic studies. The first stage, associated with clastic deposits sedimentation and marked by clastic grains dense structural packing formation, close to cubic. The second diagenetic stage of quartz sandstones is associated with the subsidence stage of sediments into the burial zone. During this period were actively proceeding the processes of grains mechanical deformation, blastesis of quartz clasts, the formation of siderite fragments, and fibrous chalcedony, partially metasomatic replacing clay layers in sandstones. The third diagenetic stage in quartz sandstones is associated with the migration of underground gas-water solutions. Analysis of the transformation degree of the Pashyisky horizon quartz sandstones at different areas of the Romashkinskoye field revealed the relationship between the intensity of secondary diagenetic processes and the degree of rocks oil saturation. Keywords: pashyisky horizon; oil; sandstone; reservoir; diagenesis.

NANOSIZED STRUCTURES IN PbTe MATRIX WITH CdSe IMPURITIES

В работе проведены электронно-микроскопические исследования полупроводниковых соединений на основе PbTe с примесями дисперсных фаз CdSe. Как показали результаты исследования, в исходном нелегированном соединении PbTe содержание атомов свинца составляет около 63,8 вес%, а содержание теллура составляет 36,2 вес%, т.е. соответствует стехиометрическому составу. Согласно изображениям электронного микроскопа, эти компоненты равномерно распределены по площади. Результаты исследования также показали, что образующиеся новые фазы имеют размеры зерен от 90 нм до 2 мкм. Полученные значения параметра решетки для соединения теллурида свинца и сингония хорошо согласуются с литературными данными. Структура образующихся фаз имеет такую же симметрию, как и исходное нелегированное соединение PbTe, гранецентрированную кубическую решетку с классом симметрии Fm3m. В молекулах новых образующихся фаз, в которых преобладают содержания элементов Cd и Se, обнаружено изменение сингонии кристаллической решетки. In this work, electron microscopic studies of semiconductor compounds based on PbTe with impurities of dispersed CdSe phases have been carried out. As shown by the research results, in the initial undoped PbTe compound, the content of lead atoms is about 63,8 wt.%, and the tellurium content was 36,2 wt.%, i.e. corresponded to the stoichiometric composition. According to the electron microscope images, these components are evenly distributed over the area. The results of the study also showed that the formed new phases had grain sizes from 90 nm to 2 pm. The obtained values of the lattice parameter for the lead telluride compound and crystal system are in good agreement with the literature data. The structure of the resulting phases has the same symmetry as the initial undoped PbTe compound, a face-centered cubic lattice with the Fm3m symmetry class. In the molecules of the newly formed phases, in which the abundances of the elements Cd and Se prevailed, a change in the crystal lattice syngony was found.

Characterization of Macro Mechanical Properties and Microstructures of Cement-Based Composites Prepared from Fly Ash, Gypsum and Steel Slag

Using solid wastes (SWs) as backfilling material to fill underground mined-out areas (UMOAs) solved the environmental problems caused by SWs and reduced the backfilling cost. In this study, fly ash (FA), gypsum and steel slag (SS) were used to prepare cement-based composites (CBC). The uniaxial compression, computed tomography (CT) and scanning electron microscope (SEM) laboratory experiments were conducted to explore the macro and micromechanical properties of CBC. The findings showed that the uniaxial compressive strength (UCS) of CBC with a curing time of 7 d could reach 6.54 MPa. The increase of SS content reduced the UCS of CBC, while the gypsum and FA content could increase the UCS of CBC. Microscopic studies have shown that the SS particles in CBC have noticeable sedimentation, and the increase of SS content causes the failure mode of CBC from tensile to tensile-shear. These research results can provide a scientific reference for the preparation of backfilling materials.

GÜZELYURT – ABBASLAR ARASINDAKİ (DULKADİROĞLU – KAHRAMANMARAŞ) KAYAÇLARIN PETROGRAFİK EVRİMİ VE EKONOMİK POTANSİYELLERİ

The study area between subdistrict Güzelyurt, 11 km southeast of the city Kahramanmaraş and the Abbaslar village. Mesosoic and Senosoic age units are obsorved in the field the oldest units are tectonites, the parts of the ophiolitics series which moved into the field by mounting in the Upper Kretase. Serpantinites which are formed by the alteration of partically or completely serpantinized and harzburgite and peridotites, form the tectonites. Tectonically bordered Paleosen-Eosen limestones have came into ophiolitic series. The youngest units in the area are plateau basalts which are the results of Cretase-aged volcanism. Besides, they have proved to the different from the basalts of the ophiolitic series because they have been spilitised as regarded with the appereans in the area and they don’t show cushion flow. These rocks, defined as olivined basalt after the microscopic studies. Peridotites in the ophiolite series in the study area are noteworthy because they contain chromite. The chromites in the region take place in the peridotites as scattered grains and small pockets. Detailed studies are needed to reveal the economic values of chromites in a healthy way. Especially west of Denizli village and north of Tevekkeli village can be suggested as places where work should be intensified. However, limestones and basalts in the formations cropping out in the study area are used as building blocks in small and large settlements in the region.

Micromorphological and Pharmacognostic Studies of Leaf and Stem of Solenostemon monostachyus P. Beauv (Lamiaceae)

Solenostemon monostachyus P. Beauv (Lamiaceae), it’s ethnomedical uses include anti-plasmodial, anti-pyretic, antiulcerogenic, antioxidant, anti-inflammatory and anti-nociceptive activities. The aim of this study was to employ the quality control parameters in the evaluation of the leaf and stem of Solenostemon monostachyus to aid in the identification and standardization of the medicinal plant. The plant leaves and stems were collected, identified, air-dried, pulverized and stored in separate glass containers. Standard procedures were employed to obtain the microscopic features of the fresh and powdered samples, micromeritic, chemomicroscopy, fluorescence properties, moisture contents, ash values and soluble extractive values. The results of the microscopic studies using fresh and powdered leaf samples revealed the presence of diacytic stomata on both the abaxial and adaxial surfaces (amphistomatic), with stomatal index of 27.9% and 14.8% respectively. The result of the micromeritics properties of the powdered leaf and stem samples showed angles of repose of 38.0o and 46.0o, Carr’s index of 23.7% and 32.5% and Hausner’s ratios of 1.3 and 1.5 respectively. Results for the moisture content, total, acid-insoluble and water-soluble ash values were 11.7%w/w, 13.7%w/w, 1.8%w/w and 9.4%w/w for the leaf and 13.3%w/w, 17.3%w/w, 1.8%w/w and 9.2%w/w for the stem respectively. Extractive values for water-soluble, methanol-soluble and ethanol-soluble were 26.5%w/w, 32.3%w/w, 14.5%w/w and 15.5%w/w, 15.8%w/w and 14.5%w/w for the leaf and stem respectively. Chemomicroscopy indicated the presence of lignin, calcium oxalate crystals and protein in the leaf and stem. The results obtained therefore could be used to establish pharmacopoeial standard for the fresh and powdered drug products of Solenostemon monostachyus, thus preventing adulteration.

Phenotypical and Myopathological Consequences of Compound Heterozygous Missense and Nonsense Variants in SLC18A3

Background: Presynaptic forms of congenital myasthenic syndromes (CMS) due to pathogenic variants in SLC18A3 impairing the synthesis and recycling of acetylcholine (ACh) have recently been described. SLC18A3 encodes the vesicular ACh transporter (VAChT), modulating the active transport of ACh at the neuromuscular junction, and homozygous loss of VAChT leads to lethality. Methods: Exome sequencing (ES) was carried out to identify the molecular genetic cause of the disease in a 5-year-old male patient and histological, immunofluorescence as well as electron- and CARS-microscopic studies were performed to delineate the muscle pathology, which has so far only been studied in VAChT-deficient animal models. Results: ES unraveled compound heterozygous missense and nonsense variants (c.315G>A, p.Trp105* and c.1192G>C, p.Asp398His) in SLC18A3. Comparison with already-published cases suggests a more severe phenotype including impaired motor and cognitive development, possibly related to a more severe effect of the nonsense variant. Therapy with pyridostigmine was only partially effective while 3,4 diaminopyridine showed no effect. Microscopic investigation of the muscle biopsy revealed reduced fibre size and a significant accumulation of lipid droplets. Conclusions: We suggest that nonsense variants have a more detrimental impact on the clinical manifestation of SLC18A3-associated CMS. The impact of pathogenic SLC18A3 variants on muscle fibre integrity beyond the effect of denervation is suggested by the build-up of lipid aggregates. This in turn implicates the importance of proper VAChT-mediated synthesis and recycling of ACh for lipid homeostasis in muscle cells. This hypothesis is further supported by the pathological observations obtained in previously published VAChT-animal models.