72 research outputs found
Generation of low-temperature plasma by low-pressure arcs for synthesis of nitride coatings
Experiments were performed to study gas, metal, and mixed metal-gas plasmas. The plasmas were generated with the use of an arc evaporator and a gas-plasma source with a hot filament and hollow cathode that were operated independently or simultaneously. It has been revealed that the arc current of gas-plasma source affects the parameters of the metal-gas plasma and the element concentrations in the coatings. It has been demonstrated that the characteristics of the nitride coatings produced by plasma-assisted vacuum-arc deposition can be controlled by varying the parameters of the arc in the gas-plasma source
Graphoanalytical method for determining the indicators of thermal-oxidative stability of lubricating oils
Noncompact SL(2,R) spin chain
We consider the integrable spin chain model - the noncompact SL(2,R) spin
magnet. The spin operators are realized as the generators of the unitary
principal series representation of the SL(2,R) group. In an explicit form, we
construct R-matrix, the Baxter Q-operator and the transition kernel to the
representation of the Separated Variables (SoV). The expressions for the energy
and quasimomentum of the eigenstates in terms of the Baxter Q-operator are
derived. The analytic properties of the eigenvalues of the Baxter operator as a
function of the spectral parameter are established. Applying the diagrammatic
approach, we calculate Sklyanin's integration measure in the separated
variables and obtain the solution to the spectral problem for the model in
terms of the eigenvalues of the Q-operator. We show that the transition kernel
to the SoV representation is factorized into a product of certain operators
each depending on a single separated variable.Comment: 29 pages, 12 figure
The open XXZ and associated models at q root of unity
The generalized open XXZ model at root of unity is considered. We review
how associated models, such as the harmonic oscillator, and the lattice
sine-Gordon and Liouville models are obtained. Explicit expressions of the
local Hamiltonian of the spin XXZ spin chain coupled to dynamical
degrees of freedom at the one end of the chain are provided. Furthermore, the
boundary non-local charges are given for the lattice sine Gordon model and the
harmonic oscillator with open boundaries. We then identify the spectrum and
the corresponding Bethe states, of the XXZ and the q harmonic oscillator in the
cyclic representation with special non diagonal boundary conditions. Moreover,
the spectrum and Bethe states of the lattice versions of the sine-Gordon and
Liouville models with open diagonal boundaries is examined. The role of the
conserved quantities (boundary non-local charges) in the derivation of the
spectrum is also discussed.Comment: 31 pages, LATEX, minor typos correcte
ПЕРСПЕКТИВЫ ПОЛУЧЕНИЯ ПРОРОСТКОВ СЕМЯН ЛУКОВЫХ КУЛЬТУР, ОБОГАЩЕННЫХ СЕЛЕНОМ
Sprouts of agricultural crops seeds are considered to be functional food products with high content of antioxidants. Though seeds of Allium species plants are used in some countries as spices the possibilities of appropriate sprouts utilization have never been investigated so far. Evaluation of perennial and A. cepa seeds biofortification with selenium revealed high nutritional value of the resulting sprouts characterized not only by high selenium content exclusively in a form of selenomethyl selenocysteine (a natural anti carcinogen) but also with high levels of antioxidant activity and high polyphenol content. It was demonstrated that among seven studied representatives of Allium species Allium cepa variety Krasnoye krugevo and perennial onion Allium fistulosum give seeds sprouts with the highest levels of selenium (10500-11000 μg/kg d.w.), polyphenols (9.3-10.8 mg-eq GA/g d.w) and the largest values of antioxidant activity (14.7-17.1 mg-eq GA/g d.w.). Utilization of one g of dried seeds sprouts powder, fortified with selenium provides up to 15.7% of the adequate consumption level of selenium exclusively in a form of selenomethyl selenocysteine possessing powerful anti carcinogenic activity.Проростки семян сельскохозяйственных культур являются функциональными продуктами питания с высоким содержанием природных антиоксидантов. Хотя семена растений рода Allium используют в ряде стран в качестве приправы, однако возможности использования соответствующих проростков в пищу ранее не исследовались. Оценка эффективности обогащения семян многолетних луков и лука репчатого селеном выявила высокую пищевую ценность получаемого продукта, отличающегося не только высоким содержанием селена, причем преимущественно в виде селенометил селеноцистеина, мощного природного антиканцерогена, но также повышенным уровнем антиоксидантной активности и высоким содержанием полифенолов. Установлено, что среди 7 исследованных представителей рода Allium наиболее перспективными являются проростки семян лука репчатого Красное кружево и многолетнего лука батуна, содержащих наиболее высокие уровни селена (10500-11000 мкг/кг с.м), полифенолов (9,3-10,8 мг-экв ГК/1 г с.м.) и имеющих наибольший уровень антиоксидантной активности (14,7-17,1 мг-экв ГК/1 г с.м.). Использование 1 г порошка высушенных проростков лука, обогащенных селеном, обеспечивает поступление в организм человека до 15,7% суточной потребности человека в селене, причем в виде селенометил селеноцистеина, обладающего высокой антиканцерогенной активностью
Ion Channel Density Regulates Switches between Regular and Fast Spiking in Soma but Not in Axons
The threshold firing frequency of a neuron is a characterizing feature of its dynamical behaviour, in turn determining its role in the oscillatory activity of the brain. Two main types of dynamics have been identified in brain neurons. Type 1 dynamics (regular spiking) shows a continuous relationship between frequency and stimulation current (f-Istim) and, thus, an arbitrarily low frequency at threshold current; Type 2 (fast spiking) shows a discontinuous f-Istim relationship and a minimum threshold frequency. In a previous study of a hippocampal neuron model, we demonstrated that its dynamics could be of both Type 1 and Type 2, depending on ion channel density. In the present study we analyse the effect of varying channel density on threshold firing frequency on two well-studied axon membranes, namely the frog myelinated axon and the squid giant axon. Moreover, we analyse the hippocampal neuron model in more detail. The models are all based on voltage-clamp studies, thus comprising experimentally measurable parameters. The choice of analysing effects of channel density modifications is due to their physiological and pharmacological relevance. We show, using bifurcation analysis, that both axon models display exclusively Type 2 dynamics, independently of ion channel density. Nevertheless, both models have a region in the channel-density plane characterized by an N-shaped steady-state current-voltage relationship (a prerequisite for Type 1 dynamics and associated with this type of dynamics in the hippocampal model). In summary, our results suggest that the hippocampal soma and the two axon membranes represent two distinct kinds of membranes; membranes with a channel-density dependent switching between Type 1 and 2 dynamics, and membranes with a channel-density independent dynamics. The difference between the two membrane types suggests functional differences, compatible with a more flexible role of the soma membrane than that of the axon membrane
APPLICATION OF A SURFACE-RENEWAL MODEL TO PERMEATE-FLUX DATA FOR CONSTANTPRESSURE CROSS-FLOW MICROFILTRATION WITH DEAN VORTICES
Research results of makeup influence on semi-synthetic motor oils thermal oxidation stability
During the running motor oil quality determination oil makeup has a big influence on thermal oxidation mechanism, however there is a problem of insufficient examination of makeup influence on motor oil conditions. Main goal of these researches is to determine how makeup effects on motor oil’s thermal oxidation stability. For the research Lube oil Lukoil Super 10W-40 SG/CD has been chosen. Thermal oxidation stability results assessment was conducted basing on obtained values of: light stream absorption criteria, volatility and thermal oxidation stability criteria in cases of research with makeup and without it. There was offered a criteria of makeup influence on thermal oxidation stability values, which identified as change of light stream absorption rate proportion and thermal oxidation stability criteria in case of research with and without makeup. Research methodology involved motor oil test on thermostating device consequently under temperatures 180, 170 and 160 °С with makeup and without it in condition when quantity of makeup oil corresponded to vaporized oil quantity. Research results demonstrated that oil makeup decrease thermal oxidation intensity on the whole temperature test rate
Graphoanalytical method for determining the indicators of thermaloxidative stability of lubricating oils
Research of engine and transmission oils for thermo-oxidative stability with cyclic temperature changes
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