Numerical And Experimental Study Of Multi-Point Forming Of Thick Double-Curvature Plates From Aluminum Alloy 7075

The paper describes various rod type work tools intended for forming parts and their design peculiarities and technological processes they are used in. We present the device for multi-point forming thick double-curvature plates with the use of reconfigurable core punch and die in large temperature and speed range. The results of finite element modeling of forming and machining process are demonstrated. It is revealed that heating the work piece results in pressing of the rod into the work piece in the areas of maximum pressure. The depth of pressing depends on mechanical behavior of the material at forming temperature and force to forming rods. The paper presents the results of experiments on developing of multi-point forming plates

Fabrication and properties of L-arginine-doped PCL electrospun composite scaffolds

The article describes fabrication and properties of composite fibrous scaffolds obtained by electrospinning of the solution of poly({\epsilon}-caprolactone) and arginine in common solvent. The influence of arginine content on structure, mechanical, surface and biological properties of the scaffolds was investigated. It was found that with an increase of arginine concentration diameter of the scaffold fibers was reduced, which was accompanied by an increase of scaffold strength and Young modulus. It was demonstrated that porosity and water contact angle of the scaffold are independent from arginine content. The best cell adhesion and viability was shown on scaffolds with arginine concentration from 0.5 to 1 % wt

Features of pulsed synchronization of a systems with a tree-dimensional phase space

Features of synchronization picture in the system with the limit cycle embedded in a three-dimensional phase space are considered. By the example of Ressler system and Dmitriev - Kislov generator under the action of a periodic sequence of delta - function it is shown, that synchronization picture significantly depends on the direction of pulse action. Features of synchronization tons appeared in these models are observed.Comment: 16 pages, 11 figure

Photoinduced Absorption in Bismuth Titanate Crystals on Nano- and Picosecond Excitation

The peculiarities in the induced absorption of bismuth titanate (Bi12TiO20) crystals upon their irradiation by high intensity nano and picosecond pulses with a wave length of 532 nm have been studied. The relationship between the photochromic effect and radiation intensity at the fixed radiation dose in con ditions of pulsed laser excitation has been established. A threshold character of the relationship between the photochromic effect and intensity has been found for the first time. A phenomenological model making it possible to explain qualitatively the dynamics of the trapping level population process has been proposed

TRIS I: Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82 and 2.5 GHz

At frequencies close to 1 GHz the sky diffuse radiation is a superposition of radiation of Galactic origin, the 3 K Relic or Cosmic Microwave Background Radiation, and the signal produced by unresolved extragalactic sources. Because of their different origin and space distribution the relative importance of the three components varies with frequency and depends on the direction of observation. With the aim of disentangling the components we built TRIS, a system of three radiometers, and studied the temperature of the sky at $\nu =0.6$, $\nu = 0.82$ and $\nu = 2.5$ GHz using geometrically scaled antennas with identical beams (HPBW = $18^{\circ} \times 23^{\circ}$). Observations included drift scans along a circle at constant declination $\delta=+42^{\circ}$ which provided the dependence of the sky signal on the Right Ascension, and absolute measurement of the sky temperature at selected points along the same scan circle. TRIS was installed at Campo Imperatore (lat. = $42^{\circ}~26'$ N, long.= $13^{\circ}~33'$, elevation = 2000 m a.s.l.) in Central Italy, close to the Gran Sasso Laboratory.Comment: Accepted for publication in The Astrophysical Journa

Исследование экстракта из лишайника Cetrária islándica после ультразвукового воздействия

An integral part of human healthy nutrition is intake of biologically active substances. Extraction is an important stage of isolation of different bioactive substances from plants and effectiveness of their extraction increases with the use of ultrasonic treatment. The aim of this research was to study an effect of different types of aqueous media and treatment methods on Cetraria islandica, including the use of principles of ultrasonic treatment and maceration methods (infusion). The experimental studies consisted in detecting an effect of the active acidity of the aqueous medium (solvent) and method of impact upon extraction on several physicochemical and rheological indicators. The experimental samples of extracts were examined by the following indicators: active acidity and redox potential detected by the ionometric technique; dynamic viscosity and the depth of output of polymeric forms of phenolic substances determined by measuring the optical density and transmission coefficient. Mathematical processing of data using the regression analysis was carried out. The results are presented as graphs, tables and regression equations. It has been established that transfer of substances from Cetraria islandica to its extracts had high results at pH = 7.0 and рН = 9.0 of the solvent. When obtaining extracts by the infusion method, the quantity of polymeric compounds in the transition process was 1.3 times higher than the quantity of monomeric forms of phenolic compounds. The highest value of the dynamic viscosity was revealed in the extract sample obtained by the infusion method in the alkaline medium. The extracts obtained can be used in food system modeling.Неотъемлемой частью здорового питания является поступление в организм человека биологически активных соединений. Экстракция — важнейший этап выделения из растений различных биоактивных веществ, и эффективность их извлечения повышается в совокупности с ультразвуковой обработкой. Цель данного исследования — изучить влияние различных видов водной среды и способов обработки на цетрарию исландскую, в том числе с использованием принципов ультразвуковой обработки и методом мацерации (настаивание). Экспериментальные исследования заключались в установлении влияния активной кислотности водной среды (растворителя) и метода воздействия при проведении экстракции на ряд физико-химических и реологических показателей. Исследованы опытные образцы экстрактов по следующим показателям: активная кислотность и окислительно-восстановительный потенциал, выявленные с помощью ионометрического метода; динамическая вязкость и глубина выхода полимерных форм фенольных веществ, установленные измерением оптической плотности и коэффициента пропускания. Проведена математическая обработка данных с использованием регрессионного анализа. Результаты представлены в виде графиков, таблиц и уравнений регрессии. Установлено, что переход веществ из цетрарии исландской в экстракты из нее имели высокие результаты при рН = 7,0 и рН = 9,0 растворителя. При получении экстрактов методом настаивания количество полимерных соединений в процессе перехода в 1,3 раза превышало число мономерных форм фенольных соединений. Наибольшее значение по исследуемому показателю «динамическая вязкость» было выявлено в образце экстракта, полученном методом настаивания в щелочной среде. Выделенные экстракты могут быть применены при моделировании пищевых систем

Hydrogel Cross-Linking via Thiol-Reactive Pyridazinediones

Thiol-reactive Michael acceptors are commonly used for the formation of chemically cross-linked hydrogels. In this paper, we address the drawbacks of many Michael acceptors by introducing pyridazinediones as new cross-linking agents. Through the use of pyridazinediones and their mono- or dibrominated analogues, we show that the mechanical strength, swelling ratio, and rate of gelation can all be controlled in a pH-sensitive manner. Moreover, we demonstrate that the degradation of pyridazinedione-gels can be induced by the addition of thiols, thus providing a route to responsive or dynamic gels, and that monobromo-pyridazinedione gels are able to support the proliferation of human cells. We anticipate that our results will provide a valuable and complementary addition to the existing toolkit of cross-linking agents, allowing researchers to tune and rationally design the properties of biomedical hydrogels

Research of vein-protective effect of the preparation "Agsular”® on the models of 106 vascular pathology

Varicose disease is the most common vascular pathology of lower extremities that causes development of chronic venous insufficiency (CVI). Modern Russian pharmaceutical market of medicines external application used in phlebology is mainly presented by expensive imported medicines. That's why development of original Russian high-effective and. available medicines for prevention, and. treatment of chronic venous insufficiency is an actual problem of medical and. pharmaceutical sciences. Pharmacologically active substance 'Asgular®" that has hypolipidemic and anticoagulant activity was developed in A.E. Favorsky Irkutsk Institute of Chemistry SB RAS as the result of chemical modification of polysaccharide of Siberian larch. Original pharmaceutical compositions (preparation. "Asgular®") in solid and. liquid medicinal forms for external application in forms of hydrophilic gel and rectal capsules with hydrophilic gel were developed on the basis of that active substance. Veinprotective effect of "Agsular®" preparation was studied on the models of vascular pathology. It was determined. that antiinflammatory activity and. anti-transudative effect — decrease of vessels' permeability and increase of their walls' tone — were of most importance in the mechanism of veinprotective effect of the preparation "Agsular"®. Anti-inflammatory activity is developed in decrease of intensity of neutrophil infiltration in wound, area and. in anti-exudative effect that is presented by the decrease of stroma and cell hypostases. Thus our researches indicates prospectivity of use of "Agsular'® preparation for prevention and. treatment of chronic venous insufficiency and varicosis in particular