North-south asymmetry of geomagnetic and tropospheric events

The influences of the solar plasma on geomagnetic and atmospheric phenomena are considered. There are the north-south asymmetry in the reaction of the geomagnetic field, of the geopotential and of the pressure in the magnetically conjugate points relative to the direction of the interplanetary magnetic field. There are the synchronism between direction of the meridinal component of wind at the level of the tropopause and the direction of the interplanetary magnetic field. © 1974

Growth of 3C-SiC Films on Si (111) and Sapphire (0001) Substrates by MOCVD

Thick silicon carbide films were grown on sapphire (0001) and silicon (111) substrates using metal organic chemical vapor deposition (MOCVD). Diethylmethylsilane (DEMS) has been used as a single precursor, which contain Si and C atoms in the same molecule, without any carrier or bubbler gas. Atomic structure, surface composition and morphology have been investigated by XRD, AES, SEM and AFM analysis. SiC films of 5-7 micron thickness were grown at a rate of ~ 40 nm/min on sapphire (0001) and Si (111) substrates. The films grown at low temperature (850 ºC and 900 ºC) on both substrates show crystalline 3C-SiC in the (111) orientation. XRD results show that the orientation of the crystal structure does not depend of the substrate orientation AFM pictures of SiC films grown on sapphire (0001) exhibit more crystalline order as compared to films grown on the Si (111) substrates. AES of the grown films shows that in both cases the Si peak intensity is greater than that of carbon. This work shows promise for the development of alternative processes for developing low cost, large area substrates for application to IIInitrides LED and UV photodetector fabrication and also for gas detector application

Formation of Hydroxyapatite Coating by Mechanical Alloying Method

Hydroxyapatite [Ca10(PO4)6(OH)2 − HA] material has been clinically applied in many areas of dentistry and orthopaedics. Presented work describes the effect of mechanical alloying treatment, as a non-conventional solid-state process, on the microstructure of hydroxylapatite powder and Ti-alloy substrate. The relationship between the crystallinity, crystallite size and strain of the HA with milling factors was investigated. Milled HA powders and Ti-substrate were characterized by X-Ray Diffraction (XRD) and/or scanning probe microscope (SPM) using atomic force microscopy (AFM). Increasing the ratio of the weight of the ball to the powder (Wb:Wp) ratio and milling time accelerates the broadening and intensity reduction of XRD peaks. There was no evidence that milling time up to 2 hrs or Wb:Wp can change chemical composition of the HA. Decomposition of HA phase or secondary phases such as α and/or β-tri-calcium phosphate (α, β − TCP), and calcium oxide (CaO) was not observed throughout the milling process. The average grain size and the internal strain are calculated from the XRD by Scherrer's formula and Hall–Williamson method. The Ti doped HA samples shows a notable broadening and intensity reduction comparing with HA powders before and after milling

Self-Propagating High Temperature Synthesis of Composition Materials using Mineral Raw Materials

The possibility of obtaining multicomponent refractory composition materials on the basis of quarts containing raw material by SHS method was studied. The use of a modifying carbon additive in the form of graphite power, carbonized rice husk, apricot stones and shungit was considered. It is shown that a complex use of preliminary mechanochemical activation (MA) and modification of the charge mixture with carbon containing additives contributes to formation of carbide and nitride phases in synthesis products

Study of Sorption Capacity and Surface Morphology of Carbon Nanomaterials/Chitosan Based Aerogels

In this research aerogels were synthesized by homogenization of carbon nanotubes and chitosan under ultrasonic treatment and active magnetic stirring, followed by freeze-drying in order to remove the liquid from its structure. Freeze-drying is characterized by a certain ratio of pressure and temperature at which the solid phase, in our case – the ice, turns into a gas without passing through a liquid phase. Freezedrying was carried out at a temperature of –15 °C and a pressure of 30–40 Pa. After freeze-drying which lasted for 20 h, the as-obtained aerogels were carbonized at temperature of 800 °C in an inert atmosphere. Surface morphology of resulting aerogels was studied using scanning electron microscopy. The hydrophobicity and sorption capacity of these aerogels to organic liquids characterized by different densities were investigated. In addition, composite aerogels with the presence of graphene nano-platelets in the structure were obtained and the influence of introduction of graphene nanoplatelets on aerogel’s properties was analyzed. It was found that composite aerogels based on graphene and carbon nanotubes with chitosan as a glue matrix are characterized by a better-developed porosity of surface with a smaller pore sizes, and their sorption capacity for organic liquids is higher compared with the aerogels based on carbon nanotubes

Surgical treatment of the ascending aorta giant aneurysm

We shared our experience of surgical treatment of a giant aneurysm of the ascending aorta (11 cm) in a female patient with bicuspid valve, arterial hypertension and severe obesity.  We performed aortic valve replacement and supracoronary prosthetic replacement of ascending aorta.  She showed improvement in clinical status, echocardiography, and was discharged and followed up for 5 months after operation. Control computed tomography angiography demonstrated functioning aortic prosthetic graft