Effect of Cilia Orientation in Metachronal Transport of Microparticles

A biomimetic approach is used to generate a directed transversal transportation of micron-sized particles in liquids based on the principle of cilia-type arrays in coordinated motion. Rows of flaps mimicking planar cilia are positioned off-centre along an array of cavities covered with membranes that support the flaps. These membranes are deflected from a concave to a convex shape and vice versa by pneumatic actuation applying positive and negative pressures (relative to the ambient) inside the cavities. As a result, the flap on top of the membrane tilts to the left or right within such a pressure cycle, performing a beat stroke. Since each cavity can be addressed in the device individually and in rapid succession, waves of coordinated flap motion can be run along the wall. Such metachronal waves are generated and transport of particles along the cilia surface is achieved in both symplectic and antiplectic direction. It is shown that the initial tilt of the flaps relative to the wall-normal determines the direction of transport

Transmission and diffraction of impulse waves in foam media with cavities

Widespread use of foam materials in construction, which makes it possible to significantly reduce the cost and facilitate construction, caused increasing interest in the development of methods studying the stress state of such materials during action of various dynamic loads triggered by technological and mechanical influences. Research of transmission of waves that arises from the effects of such influences will give an opportunity to more accurately assess the strength of such structural elements and the effectiveness of their use. The aim of the work is to develop a method for studying the transmission and diffraction of elastic impulses in foam materials with tunnel cavities of an arbitrary cross-section.In order to solve the problem the boundary integral equations method was used together with the time Fourier transform, which made it possible to obtain integral equations in a complex form for the Cosserat pseudo-continuum. Using the developed approach the research of transmission and diffraction of weak shock waves on tunnel cavities in foam media was carried out based on the analysis of fields of dynamic and radial stresse

Production of retardation film with pixel strusture

At present the commercial success of LC displays is achieved due to the high characteristics of quality: viewing angles, contrast, price, etc. For example, LC display have been used for creation of 3D images by means of forming images on the display for the left and right eye and using of polarizing glasses for the left and right eye. It allows us to see the resulting 3D image. Such a system can be implemented by means of using of a pattern phase retardation film which is placed on the display screen. The retardation film is a structured phase plate with display pixels order resolution which allows to form lines of images for the left and right eye without loss of image quality

Fluid transport via pneumatically actuated waves on a ciliated wall

To manipulate fluids actively a pneumatically actuated micro membrane device is developed to generate a directed transversal fluid transport in a liquid layer next to the wall. The biomimetic approach is based on the principle of cilia-type arrays that generate a mean flow by travelling wave activation. Rows of long flaps, which mimic the comb row of a ctenophore, are positioned off-centre along a row of cavities. Each cavity is covered by a flexible membrane that supports the flaps. The membranes with the flaps on top are deflected by applying a well-defined pressure profile to the cavities under the membranes such that an individual beat can be generated for each flap. Flow visualization experiments were carried out under the conditions of travelling waves. The results show a mean velocity profile that resembles that of a wall-jet. Mixing effects with increased retention times of the fluid occur in the vicinity of the membrane surfaces

Potential of Antifungal Drugs as Photosensitizers

In the present work, using commercially available formulation of polyene antifungal antibiotic amphotericin B, it is shown that its antifungal activity could be enhanced in combination with optical radiation corresponding to the absorption band of amphotericin B due to photodynamic effect. It is assumed that the radical processes dominate in the mechanism of photodynamic action in the presence of amphotericin B. Keywords: Amphotericin B, antimicrobial/antifungal photodynamic therapy (aPDT), lactate dehydrogenase (LDH), singlet oxygen, laser, LED

Biological Effect of Continuous, Quasi-Continuous and Pulsed Laser Radiation

In this work, for the first time, comparative studies of biological activity of low intensity continuous, quasi-continuous and pulsed laser radiation of nano- and picosecond time ranges with the same average power density are carried out. It is shown, that, despite the significant differences in peak values of intensity of acting factor, both continuous and quasi-continuous radiation and radiation of nano- and picosecond ranges are able to have both stimulating and inhibiting effects on all investigated parameters of functional activity of biological systems in a certain range of dose rates. The ability of laser radiation of near infra-red spectral region (800 - 1340 nm) located out the absorption bands of main chromophores of cells to have regulatory effect on biochemical processes that control the hatching of branchiopod crustaceans Artemia salina L. upon irradiation of their cysts is revealed. The role of molecular oxygen and water as acceptors of laser radiation is discussed. Keywords: Low intensity laser radiation, Laser activation, Biological activity, Zooplankton Artemia salina L., Sturgeon sperm

Calculation of the stability of composite rods according to the non-classical bending model

The problem of the effect of deformations of transverse shear and transverse compression on the value of the critical stress in the problem of the loss of stability of a transversely isotropic rod is considered. The fourth-order differential equation of the nonclassical bending model of rods is applied. Formulas for the critical stress are obtained, as well as numerical results for rods made of different material

Comprehensive Study of Ni Nanotubes for Bioapplications: From Synthesis to Payloads Attaching

Due to the Ni nanotubes’ shape anisotropy, low specific density, large specific surface, and uniform magnetic field, they have been offered as carriers for targeted delivery of drug or protein and the process of their formation from synthesis stage to the stage of surface modification and protein attaching has been demonstrated. Some steps to hasten their biomedical application have been applied. First, to have full control over the carrier dimensions and structure parameters, electrodeposition method in pores of polyethylene terephthalate template has been applied. Second, to understand the scope of Ni nanostructures application, their degradation in media with different acidity has been studied. Third, to improve the biocompatibility and to make payloads attachment possible, nanotubes surface modification with organosilicon compound has been carried out. At last, the scheme of protein attaching to the nanostructure surface has been developed and the binding process was demonstrated as an example of the bovine serum albumin

ПОЛУЧЕНИЕ КЛИНКЕРНОГО КИРПИЧА НА ОСНОВЕ МИНЕРАЛЬНОГО СЫРЬЯ РЕСПУБЛИКИ БЕЛАРУСЬ

Mass compositions for production of dense ceramics, in particular clinker bricks based on low-melting clays, loams, low-calcined chamotte and cullet glass have been developed. A positive effect of finely ground low-ash chamotte obtained by heat treatment of low-melting clays at 1000 °C, which contributes to the expansion of the sintering interval of materials, is established. The complex use of polymineral clays, low-calcined chamotte and loams allows obtaining dense-looking material with a water absorption of 3–5 %, which is due to the effective action of fine-dispersed amorphous silica contained in loam. Dense material with a less than 5 % water absorption, frost resistance of 120–200 thermal cyclings and mechanical compressive strength of 41–47 MPa was produced by calcination of the mentioned materials at 1150 ± 10 °C. Проведены исследования и разработаны составы масс для получения плотноспекшейся керамики, в частности клинкерного кирпича, на основе легкоплавких глин, суглинков, низкожженного шамота и стеклобоя тарного. Установлено положительное влияние тонкомолотого низкожженого шамота, полученного термообработкой легкоплавких глин при 1000 °С, который способствует расширению интервала спекания материалов. Комплексное использование полиминеральных глин, низкожженого шамота, суглинков позволяет получить плотноспекшийся материал с водопоглощением 3–5 %, что обусловлено эффективным воздействием тонкодисперсного аморфного кремнезема, содержащегося в суглинках. Выявлено, что при таком использовании указанных компонентов при температуре обжига 1150±10 °С получен плотноспекшийся материал с водопоглощением менее 5 %, морозостойкостью 120–200 циклов и механической прочностью при сжатии 41–47 МПа.

Препаративный синтез N-ацетил-3-индолинонов

Compounds that contain an indole cycle in their structure have biological activity and are a source for the development of new medicinal products. N-acetyl-3-indolinones are actively used as incoming substance for their organic synthesis. Preparative methods for the obtaining of N-acetyl-3-indolinones, used as incoming substances for the synthesis of condensed indole derivatives with high therapeutic activity, have been developed. Synthesis of N-acetyl-3-indolinone was performed by deacetylation and cyclization of N-(2-carboxyphenyl) glycine and its 4-bromo-derivative to form N,O-diacetylindoxyls followed by hydrolysis of the obtained compounds to target indolinones. It was established that brominated derivatives have increased stability as compared with the analogues which do not contain bromine on the benzene ring of the indole nucleus, resulting in the increase in the yield of desired products in the reaction.Соединения, содержащие в своей структуре индольный цикл, обладают биологической активностью и являются источником для разработки новых лекарственных средств. Для их органического синтеза активно используются в качестве исходных веществ N-ацетил-3-индолиноны. Разработаны препаративные методики получения N-ацетил-3-индолинонов, применяемых в качестве исходных соединений для синтеза конденсированных производных индола, обладающих высокой терапевтической активностью. Синтез N-ацетил-3-индолинонов осуществляли путем диацетилирования и циклизации N-(2-карбоксифенил)глицина и его 4-бромпроизводного с образованием N,O-диацетилиндоксилов с последующим гидролизом полученных соединений до целевых индолинонов. Установлено, что бромзамещенные производные обладают повышенной стабильностью по сравнению с аналогами, не содержащими брома в бензольном кольце индольного ядра, в результате чего при их использовании в реакции повышается выход целевых продуктов