Structure and electrical conductivity of polyvinyl alcohol films with multi-walled carbon nanotubes, cured in a magnetic field

The results of the study of the effect of the permanent magnetic field of a neodymium magnet on the polymerization process and the electrophysical characteristics of polyvinyl alcohol (PVA) films with the inclusion of multi-walled carbon nanotubes (MWCNTs) are presented. When studying the morphology of films using a scanning electron microscope, it was found that nanocomposite films with a thickness of 30 microns, cured in the presence of a magnetic field with the direction of the magnetic induction vector perpendicular to the surface of the films, have a homogeneous structure, while a significant number of MWCNTs agglomerations are observed in control samples of films. Measurements of the conductivity of films in the direction of the MWCNTs orientation at direct and alternating current showed that the conductivity of films obtained in a magnetic field significantly (by almost two orders of magnitude) exceeds the conductivity of control samples. The obtained results are analyzed on the basis of known models of electrical conductivity of nanocomposites with oriented MWCNTs. The degree of orientation of the MWCNTs during the curing of films in a magnetic field is estimated, taking into account the increase in the viscosity of the nanocomposite during the curing process.

Analisis Pertumbuhan Fase Superkonduktor BSCCO-2212 dan BPSCCO-2212 Akibat Variasi Suhu Sintering Menggunakan Metode Pencampuran Basah

The research was conducted to determine the effect of sintering temperature on the level of purity of the superconducting phase BSCCO-2212 and BPSCCO-2212 using the wet mixing method. Sintering was carried out for 20 hours with variations in sintering temperature: 825, 830, 835 and 840°C. XRD results showed that the phase purity level increased until it reached the optimum point at 835°C sintering temperature and then decreased at 840°C. The highest volume fraction of the BSCCO-2212 sample was obtained at a sintering temperature of 835°C at 71.09% and the highest degree of orientation was obtained at a sintering temperature of 830°C at 26.44%. In the BPSCCO-2212 sample, the highest volume fraction was obtained at a sintering temperature of 835°C at 52.59% and the highest degree of orientation at a sintering temperature of 830°C at 43.49%. The results of the comparison of BSCCO-2212 and BPSCCO-2212 samples showed that the BPSCCO-2212 sample had a higher level of phase purity than BSCCO-2212.

Genetic variations for the eggshell crystal structure revealed by genome-wide association study in chickens

Background Eggshell is a bio-ceramic material comprising columnar calcite (CaCO3) crystals and organic proteinaceous matrix. The size, shape and orientation of the CaCO3 crystals influence the microstructural properties of chicken eggshells. However, the genetic architecture underlying eggshell crystal polymorphism remains to be elucidated. Results The integral intensity of the nine major diffraction peaks, total integral intensity and degree of orientation of the crystals were measured followed by a genome-wide association study in 839 F2 hens. The results showed that the total integral intensity was positively correlated with the eggshell strength, eggshell thickness, eggshell weight, mammillary layer thickness and effective layer thickness. The SNP-based heritabilities of total integral intensity and degree of orientation were 0.23 and 0.06, respectively. The 621 SNPs located in the range from 55.6 to 69.1 Mb in GGA1 were significantly associated with TA. PLCZ1, ABCC9, ITPR2, KCNJ8, CACNA1C and IAPP, which are involved in the biological process of regulating cytosolic calcium ion concentration, can be suggested as key genes regulating the total integral intensity. Conclusions The findings greatly advance the understanding of the genetic basis underlying the crystal ultrastructure of eggshell quality and thus will have practical significance in breeding programs for improving eggshell quality.

Design of an Experimental Injection Moulding Tool for Testing Microstructured Cavity Surfaces

This research is based on the impact assessment of the active element of injection moulding tools. The quality of the tool surface has a significant effect on the filling and cooling efficiency. Our goal is to create a uniform structure on the cavity’s surface that results in a high degree of orientation during the injection moulding process. A special experimental tool is needed for the research. Our design was based on the results of previous experimental research and preliminary criteria. The design was based on the size and position tolerances of the A side of the tool. As the previous study has shown, there are three main points to consider when designing an experimental moulding tool. These are the applied manufacturing technology, Design for Assembly, and the expansion of the measurement possibilities by using different sensors. The small beam size of the femtosecond laser also allows the machining of microscopic-sized details, a technology used to structure the cavity surface. The success of this was analyzed by microscopic examination.

Fibers of Thermoplastic Copolyamides with Carbon Nanotubes for Electromagnetic Shielding Applications

Polymer composites containing carbon nanofillers are extensively developed for electromagnetic shielding applications, where lightweight and flexible materials are required. One example of the microwave absorbers can be thermoplastic fibers fabricated from copolyamide hot melt adhesives and 7 wt % of multi-walled carbon nanotubes, as presented in this paper. A broadband dielectric spectroscopy confirmed that the addition of carbon nanotubes significantly increased microwave electrical properties of the thin (diameter about 100 μm) thermoplastic fibers. Moreover, the dielectric properties are improved for the thicker fibers, and they are almost stable at the frequency range 26–40 GHz and not dependent on the temperature. The variances in the dielectric properties of the fibers are associated with the degree of orientation of carbon nanotubes and the presence of bundles, which were examined using a high-resolution scanning microscope. Analyzing the mechanical properties of the nanocomposite fibers, as an effect of the carbon nanotubes addition, an improvement in the stiffness of the fibers was observed, together with a decrease in the fibers’ elongation and tensile strength.

Corrosion Behavior of Niobium-Coated 316L Stainless Steels as Metal Bipolar Plates for Polymer Electrolyte Membrane Fuel Cells

Niobium was coated on 316L stainless steel by pulsed direct-current (DC) magnetron sputtering to improve corrosion behavior. The applied bias voltage highly affected the microstructure and crystallographic features, which lead to improved corrosion behavior. Due to the increased bias voltage, the microstructure of the niobium coating layer presented a smaller crystallite size and a densified structure, which obviously reduced the number of pinholes in the coated layer. Additionally, an increase in the degree of orientation toward the (110) plane, the most densely packed plane, lead to reduced dissolution of metal ions. Therefore, a pure niobium coating layer effectively protected the metal bipolar plate from a highly corrosive environment of polymer electrolyte membrane fuel cell (PEMFC) stacks. In particular, higher bias voltages of 600 and 800 V induced improved corrosion resistance, which satisfied the demand for the bipolar plate.

Oriented Thin Films of Insoluble Polythiophene Prepared by the Friction Transfer Technique

A thin film of unsubstituted polythiophene (PT), an insoluble conjugated polymer, with molecular chains uniaxially oriented in plane was prepared by the friction transfer method. The structure of highly oriented thin films of PT was investigated using grazing-incidence X-ray diffraction (GIXD), ultraviolet–visible (UV–vis) spectroscopy, and infrared (IR) spectroscopy. The polarized UV–vis and IR spectra and GIXD measurements showed the PT molecular chains were well aligned in parallel to the friction direction. The GIXD studies clarified that the polymer backbones were aligned with very narrow distribution, such that the half-width was about 4 degrees. The degree of orientation of the PT friction-transferred film was higher compared with those of regioregular poly(3-alkylthiophene)s. Moreover, the GIXD results show a preferred orientation where the a-axis is perpendicular to the substrate plane.

The underlying factors of foreign language reading anxiety: Their effects on strategy use and orientation toward reading

Both positive and negative emotions have been the focus of a wealth of language learning research in recent years. This can mostly be attributed to the established links between an individual’s psychological responses, existing and emerging from learning, the learning processes they engage in, and the outcomes they achieve. A look at advanced research on language anxiety, a negative emotion that appears to be strongly involved in learning, has shown that specific information about reading anxiety is comparatively insufficient. This study, therefore, examines the underlying factors of reading anxiety in Korean university students, using the Foreign Language Reading Anxiety Scale. Subsequently, it explores how these anxiety factors are related to strategy use (i.e., metacognitive, cognitive, and support strategies) and orientation toward reading, which demonstrates a reader’s active involvement while reading. Three sub-factors of reading anxiety were found: anxiety experienced during the process of reading English, confidence in reading, and anxiety when reading English characters. Interestingly, confidence or positive emotion was found to be a far more powerful positive contributor to Korean EFL university readers’ use of metacognitive strategies and the degree of orientation to reading than was anxiety experienced while reading. Pedagogical implications are discussed.

Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

Pengaruh Variasi Kadar CaCO3 terhadap Pertumbuhan Fase Superkonduktor BPSCCO–2212 Menggunakan Metode Pencampuran Basah

This research was conducted to determine the effect of CaCO3 levels on the formation of superconducting phase BPSCCO - 2212 by calculating the level of purity of the phases formed and looking at the microstructure. The variation of CaCO3 was 0.95, 1.00, 1.05 and 1.10 mole using the wet mixing method. The samples were calcined at 800 ° C for 10 hours, and sintered at 820 ° C for 20 hours. Synthesized samples were characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD’s chacterization results show that the level of purity of the formed phases increases with increasing Ca levels with maximum point at BPSCCO-2212/1.10 mole. The highest volume fraction was 79,06% in the BPSCCO-2212/1.10 sample. While the lowest volume fraction was 72.10% in the BPSCCO-2212/0.95 sample. Meanwhile, the highest degree of orientation was 20.59% at BPSCCO-2212/0.95. The lowest degree of orientation was 8.46% at BPSCCO-2212/1.10. SEM’s chacterization results show of all samples have been oriented altought not perfect yet and have relatively little space between slabs (voids).