Peculiarities of Electron-Beam Formation of Hydrophobic and Superhydrophobic Coatings Based on Hydrocarbons of Various Molecular Weights and PTFE

The paper studies the possibility of superhydrophobic coatings formations at exposure of powder mixture of polytetrafluorethylene and hydrocarbons having various molecular weights to low-energy electron beam in vacuum. It is shown that paraffin and PTFE based thin composite coatings may be characterized by superhydrophobic properties. The superhydrophobic properties are attained due to low surface energy of the fluorine-containing component and structured surface due to peculiarities of composite layer formation. The chemical processes observed in electron beam exposed area determine the molecular structure, morphology and the contact angle of thin organic coatings deposited. It is shown that high-molecular-weight hydrocarbon compounds should not be recommended for vacuum electron-beam deposition of superhydrophobic thin coatings because of deep changes in the molecular structure exposed to electron beam. These processes are responsible for high degree of unsaturation of the thin layer formed and for occurrence of oxygen-containing polar groups. The influence of substrate temperature on molecular structure, morphology and hydrophobic properties of thin coatings deposited is investigated. Potentially such coatings may be applied for deposition on the surface of metal capillaries used in biotechnological analyzers

Investigation of Nanostructured Thermoelectric Material Si0.8Ge0.2P0.022 for Application in Multisectional Legs of Thermoelectric Elements

Complex investigations of high-temperature thermoelectric material nanostructured Si0.8Ge0.2P0.022 n-type were carried out. Temperature dependencies of conductivity, thermoelectric coefficient and thermal conductivity were studied. Obtained data were used for the calculation of temperature dependence of ZT. Maximum value of ZT =1.04 is observed at 900 °C. Differential scanning calorimetry indicates on the high thermal stability of the nanostructured material. It was established that optimal temperature range for the application of the material in the multisectional legs of thermoelements is 600-900 °C

Boron-carbon coatings: structure, morphology and mechanical properties

Boron-doped carbon coatings have been produced by a method combining the deposition of a pulsed carbon plasma coating and a boron flow formed as a result of the evaporation of a boron target by pulsed YAG: Nd3+ laser irradiation. Phase, chemical composition, structure, and mechanical properties of composite boron-carbon coatings have been determined. Changes in the coatings’ roughness depending on the boron concentration have been established using atomic force microscopy. It has been shown that the grain size is on the rise with increasing boron concentration. Raman spectroscopy has revealed that at a boron concentration of 43.2 at. %. There is a sharp increase in the ID/IG ratio, which indicates the carbon component’s graphitization. Low ID/IG ratios are observed in the coating at low boron concentrations (no more than 17.4 at. %), suggesting a high content of carbon atoms with sp3 bond hybridization. The coating studies, carried out by X-ray photoelectron microscopy, showed that boron could be in a free state or in the form of carbide or oxide depending on the concentration in the coating. In this case, with an increase in boron concentration, there is a decrease in the concentration of carbon atoms in the state with sp3 bond hybridization, accompanied by an increase in the number of B-C bonds and a reduction in the boron concentration not associated with carbon and oxygen. These coating and chemical composition features determine the boron concentration’s established non-monotonic nature on their microhardness, elastic and mechanical properties

Neutron-upscattering enhancement of the triple-alpha process

The neutron inelastic scattering of carbon-12, populating the Hoyle state, is a reaction of interest for the triple-alpha process. The inverse process (neutron upscattering) can enhance the Hoyle state’s decay rate to the bound states of 12C, effectively increasing the overall triple-alpha reaction rate. The cross section of this reaction is impossible to measure experimentally but has been determined here at astrophysically-relevant energies using detailed balance. Using a highly-collimated monoenergetic beam, here we measure neutrons incident on the Texas Active Target Time Projection Chamber (TexAT TPC) filled with CO2 gas, we measure the 3α-particles (arising from the decay of the Hoyle state following inelastic scattering) and a cross section is extracted. Here we show the neutron-upscattering enhancement is observed to be much smaller than previously expected. The importance of the neutron-upscattering enhancement may therefore not be significant aside from in very particular astrophysical sites (e.g. neutron star mergers)

Investigation of Nanostructured Thermoelectric Material Si0.8Ge0.2P0.022 for Application in Multisectional Legs of Thermoelectric Elements

Complex investigations of high-temperature thermoelectric material nanostructured Si0.8Ge0.2P0.022 n-type were carried out. Temperature dependencies of conductivity, thermoelectric coefficient and thermal conductivity were studied. Obtained data were used for the calculation of temperature dependence of ZT. Maximum value of ZT =1.04 is observed at 900 °C. Differential scanning calorimetry indicates on the high thermal stability of the nanostructured material. It was established that optimal temperature range for the application of the material in the multisectional legs of thermoelements is 600-900 °C

Features of Formation of Ohmic Contacts and Gate on Epitaxial Heterostructure of AlGaN / GaN High Electron Mobility Transistor

Reported about study of processes of formation of Ti / Al / Ni / Au ohmic contacts to heterostructures AlGaN / GaN and gate Ni / Au. Investigated of process recess the semiconductor layer for minimum resistance of ohmic contact – 0.4 Ohm·mm. Studied influence of encapsulation ohmic contacts on their surface morphology

The effectiveness of radiofrequency ablation for varicose veins treatment

Varicous veins are very common for Russian population. The disease is an important cause of morbidity and it also negatively impact patients' quality of life. The management of it can be conservative or surgical.Open surgery has been the gold-standart treatment for varicose veins since the late 1800s, when Friedrich von Trendelenburg perfomed a med-thigh open ligation. Over the last 15 years surgical treatment has been moving towards minimally invasive endovascular techniques, less invasive than conventional surgery

Spherical sector model for describing the experimental small-angle neutron scattering data for dendrimers

A new model for interpreting the results of small-angle neutron scattering from dendrimer solutions is proposed. The mathematical description is given and the theoretical small-angle scattering curves for spherical sectors with different parameters are presented. It is shown that the model proposed is in good agreement with the experimental results. Comparison of the experimental small-angle neutron scattering curves for polyallylcarbosilane dendrimers of the ninth generation with model scattering curves suggests that the inner dendrimer sphere is permeable to a solvent whose density is lower than the density of the solvent beyond the dendrimer by a factor of at least 2