Lyotropic chromonic liquid crystal semiconductors for water-solution processable organic electronics

We propose lyotropic chromonic liquid crystals (LCLCs) as a distinct class of materials for organic electronics. In water, the chromonic molecules stack on top of each other into elongated aggregates that form orientationally ordered phases. The aligned aggregated structure is preserved when the material is deposited onto a substrate and dried. The dried LCLC films show a strongly anisotropic electric conductivity of semiconductor type. The field-effect carrier mobility measured along the molecular aggregates in unoptimized films of LCLC V20 is 0.03 cm^2 V^(-1) s^(-1). Easy processibility, low cost, and high mobility demonstrate the potential of LCLCs for microelectronic applications

Temperature Diffusivity Measurement and Nondestructive Testing Requiring No Extensive Sample Preparation and Using Stepwise Point Heating and IR Thermography

This chapter describes a modification to the laser flash method that allows determining temperature diffusivity and nondestructive testing of materials and constructions without cutting samples of predefined geometry. Stepwise local heating of the studied object surface at a small spot around 0.1 mm radius with simultaneous high temporary-spatial resolution infrared (IR) filming of the transient temperature distribution evolution with a thermal camera provides a wide range of possibilities for material characterization and sample testing. In case of isotropic and macroscopic homogeneous materials, the resulting transient temperature distribution is radially symmetric that renders possible to improve temperature measurement accuracy by averaging many pixels of the IR images located at the same distance from the heating spot center. The temperature diffusivity measurement can be conducted either on thin plates or on massive samples. The developed emissivity independent in plain IR thermographic method and mathematical algorithms enable thermal diffusivity measurement for both cases with accuracy around a few per cent for a wide range of materials starting from refractory ceramics to well-conducting metals. To detect defects, the differential algorithm was used. Subtracting averaged radial symmetric temperature distribution from the original one for each frame makes local inhomogeneities in the sample under study clearly discernible. When applied to crack detection in plates, the technique demonstrates good sensitivity to part-through cracks located both at the visible and invisible sides of the studied object

Enzyme Release from Polyion Complex by Extremely Low Frequency Magnetic Field

Remote nano-magneto-mechanical actuation of magnetic nanoparticles (MNPs) by non-heating extremely low frequency magnetic field (ELF MF) is explored as a tool for non-invasive modification of bionanomaterials in pharmaceutical and medical applications. Here we study the effects of ELF MF (30–160 Hz, 8–120 kA/m) on the activity and release of a model enzyme, superoxide dismutase 1 (SOD1) immobilized by polyion coupling on dispersed MNPs aggregates coated with poly(L-lysine)-blockpoly(ethylene glycol) block copolymer (s-MNPs). Such fields do not cause any considerable heating of MNPs but promote their rotating-oscillating mechanical motion that produces mechanical forces and deformations in adjacent materials. We observed the changes in the catalytic activity of immobilized SOD1 as well as its release from the s-MNPs/SOD1 polyion complex upon application of the ELF MF for 5 to 15 min. At longer exposures (25 min) the s-MNPs/SOD1 dispersion destabilizes. The bell-shaped effect of the field frequency with maximum at f = 50 Hz and saturation effect of field strength (between 30 kA/m and 120 kA/m at f = 50 Hz) are reported and explained. The findings are significant as one early indication of the nano-magneto-mechanical disruption by ELF MF of cooperative polyion complexes that are widely used for design of current functional healthcare bionanomaterials

Magnetostimulated Chandges of Microhardness in Potassium Acid Phthalate Crystals

A decrease in microhardness along the (010) cleavage in potassium acid phthalate single crystals by 15--18% after the application of a permanent magnetic field was revealed for the first time. It is shown that the effect revealed is of the volume character. The role of interlayer water in the processes stimulated by a magnetic field is studied., Interlayer water plays does not cause the observed changes it only plays the part of an indicator of these changes in potassium acid phthalate crystals in a magnetic field. It is established that microhardness in the (100) plane of the crystal in an applied a magnetic field first increases by 12--15% and then remains constant in time within the accuracy of the experiment. The possibility of varying the crystal structure of potassium acid phthalate crystals by applying magnetic fields inducing rearrangement in the system of hydrogen bonds or in the defect structure is discussed.Comment: 6 pages, 7 figure

Magnetic liposome design for drug release systems responsive to super-low frequency alternating current magnetic field (AC MF)

HYPOTHESIS: Magnetic liposomes are shown to release the entrapped dye once modulated by low frequency AC MF. The mechanism and effectiveness of MF application should depend on lipid composition, magnetic nanoparticles (MNPs) properties, temperature and field parameters. EXPERIMENTS: The study was performed using liposomes of various lipid composition and embedded hydrophobic MNPs. The liposomes structural changes were studied by the transmission electron microscopy (TEM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and the leakage was monitored by the fluorescent dye release. FINDINGS: Magnetic liposomes exposure to the AC MF resulted in the clustering of the MNPs in the membranes and disruption of the lipid packaging. Addition of cholesterol diminished the dye release from the saturated lipid-based liposomes. Replacement of the saturated lipid for unsaturated one also decreased the dye release. The dye release depended on the strength, but not the frequency of the field. Thus, the oscillating motion of MNPs in AC MF ruptures the gel phase membranes of saturated lipids. As the temperature increases the disruption also increases. In the liquid crystalline membranes formed by unsaturated lipids the deformations and defects created by mechanical motion of the MNPs are more likely to heal and results in decreased release

Using Laser Point Scanning Thermography for Quality Monitoring of Products Made of Composite Materials

Introduction. Control of the presence of subsurface defects in products from composite materials is necessary for verification of products after release from production and in the process of operation. Aim of the Study. The purpose of the presented work is to estimate the parameters of subsurface defects using local laser thermography, suitable for quality control of both small objects and suspicious areas of large objects with curved surfaces. Materials and Methods. The laboratory setup on which this work was carried out includes a robotic arm, a COX CG640 thermal imager and a 3 W laser. The method was tested on a fiberglass sample with introduced delamination defect simulations located at different depths below the surface. By means of computer modeling rational parameters of thermographic control were selected, providing reliable detection of the defect at a depth of up to 3 mm under the surface of the composite sample. Results. Numerical modeling of surface temperature field induced by moving focused laser beam was carried out using COMSOL software package. It showed that laser beam with 3 W power moving at 5 mm/s provided the thermal contrast sufficient to detect the defects at the depth up to 3 mm. The obtained experimental data are in satisfactory agreement with numerical modeling both qualitatively and quantitatively. Experimental data were used to construct a regression model for determining defect depth based on the maximal thermal contrast and the time interval between heating and the contrast maximum. Discussion and Conclusion. The results obtained in this work allow us to propose a technique for detecting defects in fiberglass plastics and estimating their depth. The coefficient of determination for the obtained regression model was found to be equal to 0.95, and the mean square error of the metric was no more than 0.016 mm2. The use of a robotic arm to scan objects will make it possible to investigate objects with complex curved surfaces

Factors of colonization resistance of oral mucous membranes in individuals using dental orthopedic constructions: peculiarities of biofilm-forming activity of microorganisms

The article presents the results of assessing the biofilm-forming ability of the oral microflora in individuals using dental orthopedic constructions. It has been established that microorganisms isolated from oral fluid of persons using removable dentures and implants have a pronounced ability to form biofilms, in comparison with the microflora of persons without dental orthopedic constructions (p<0,05).В статье представлены результаты оценки биопленкообразующей способности микрофлоры ротовой полости у лиц, использующих стоматологические ортопедические конструкции. Установлено, что микроорганизмы, выделенные из ротовой жидкости лиц, использующих съемные зубные протезы и имплантаты, обладают выраженной способностью к образованию биопленок, в сравнении с микрофлорой лиц без стоматологических ортопедических конструкций (р<0,05)

Measurement of the two-photon exchange contribution in elastic epep scattering at VEPP-3

We report on the status of the Novosibirsk experiment on a precision measurement of the ratio $R$ of the elastic $e^+ p$ and $e^- p$ scattering cross sections. Such measurements determine the two-photon exchange effect in elastic electron-proton scattering. The experiment is conducted at the VEPP-3 storage ring using a hydrogen internal gas target. The ratio $R$ is measured with a beam energy of 1.6 GeV (electron/positron scattering angles are $\theta = 55 \div 75^{\circ}$ and $\theta = 15 \div 25^{\circ}$) and 1 GeV ($\theta = 65 \div 105^{\circ}$). We briefly describe the experimental method, paying special attention to the radiative corrections. Some preliminary results are presented.Comment: 5 pages, 6 figures and 1 table; contribution to the Proceedings of the PHIPSI11 Workshop (Novosibirsk, Russia, 19-22 September 2011

Ледотехнические аспекты создания объектов транспортной инфраструктуры и разведочного бурения в Арктике

Starting from the mid 2000-s the increase of sustained development of the Russian Arctic is observed, in many cases the technologies using the ice cover as an infrastructure element and the ice as the construction materials are used. In the present time the different approaches of use of natural and artificial ice for applied tasks on the Arctic offshore exist. For example, the clearance of the upper surface of ice from snow and ridges is used for the purposes of the vessel unloading on the fast ice or constructing the airstrips on the drifting ice cover. In case of insufficient thickness of the level ice the latter is increased by the means of preliminary freezing (natural on the bottom side of ice and artificial by pouring the fresh or saline water on the upper surface). By constructing the artificial ice islands the ice body is made by spraying the sea water with the partial freezing of the water drops in the air and further freezing of the 2-phase elements (i.e. ice crystals in the liquid film) on the surface of the ice cover. The problem of cracks in the ice cover is solved by different means according to the proper task. When it is possible, the cracks are “healed”— i.e. are filled with the snow and ice gravel and then freezed. In case of impossibility of use of such method (for example — presence of tidal cracks or relatively high air temperature) the cracks are overlapped with the help of different covers made of different materials and of different sizes. The promising trend of ice technology is involving the reinforced or composite ice, having the increased strength, into the ice engineering practice. By unloading the cargo ships on the fast ice the ice strength is decreased locally for the purpose of easy berthing of the vessel with safekeeping the original strength of the surrounding ice for the aims of the vessel unloading. This problem is solved by creating the system of notches in the ice cover according to the vessel dimensions. The specialized hydrometeorological support on every stage of the ice engineering operation is an essential element of the ice engineering activities on the ice cover of lakes, rivers and seas.Рассматриваются направления ледотехники, связанные с использованием ледяного покрова природных водоемов как несущей площадки для создания транспортной инфраструктуры (ледовые причалы, аэродромы, искусственные ледяные острова и т.п.). Обсуждаются общие вопросы организации и проведения инженерно-технических работ на льду и некоторые частные проблемы, связанные с решением отдельных конкретных задач. Особое внимание уделено специальному гидрометеорологическому обеспечению операций как неотъемлемой части ледотехнических работ