Preparation and biological investigation of luminescent water soluble CdTe nanoparticles

In this study CdTe quantum dots have been successfully prepared in aqueous medium using several different thiol stabilizers. The resulting nanocrystals were purified and the photoluminescence efficiency was subsequently enhanced through post preparative procedures such as photochemical etching and ageing. An optical study was carried out on the resulting CdTe nanocrystals as proof as their improvement. Preliminary tests of the thiol stabilised QDs as potential biolabels have been performed. It has been shown that L-cysteine stabilised QDs localising to the outer cell membrane in living cells. TGA stabilised CdTe QDs can potentially serve as live cell imaging tools as they exhibit strong luminescence and excellent photostability. In addition, the ability of TGA stabilised CdTe QDs to traverse the cell membrane of macrophages is a formidable quality that may potentially be harnessed for imaging and therapeutics. Modulating the delivery of QDs to subcellular locations in living cells opens a myriad of potential applications ranging from drug delivery to examination of intracellular processes

Nanostructured metal-fullerene field emission cathode

One of the important properties of carbon nanostructures is their cold electron emission ability. Carbon nanotubes and other nanostructures are capable of emitting high currents at relatively low electrical fields. They are already used in functional devices such as field emitters. The conventional method of carbon nanostructured cathodes manufacturing is thin film nanocarbon deposition using CVD process on electrically conducting substrate like metal or doped silicon plates. The alternative way of manufacturing of carbon field emission cathodes is based on a special processing of carbon microfibers or composite materials in metal holders. We used the similar approach to produce composite metal-nanocarbon material which may be easily processed and shaped to produce an effective field emission cathode which can be easily fixed an any environment. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2058

Современные методы идентификации возбудителя гонококковойинфекции

The authors present the data on the current laboratory methods and recommendations for identifying the gonorrhea pathogen applied in Russia and abroad: microscopy method, cultural (bacteriological) study method, nucleic acid amplification techniques and DNA chip technology. The benefits and shortcomings of each of the techniques have been compared. The authors emphasize the cultural method is currently considered to be the key one for diagnosing gonorrhea due to its high specificity and sensitivity making it possible to define the N.gonorrhoeae sensitivity to antimicrobial drugs, which is very important taking into consideration the N. gonorrhoeae resistance to antibiotics. The nucleic acid amplification techniques and, first of all, polymerase chain reaction, can be used in Russia as screening methods. The results obtained by using the techniques need confirmation by the cultural method.Приведены данные о современных лабораторных методах и рекомендациях по идентификации возбудителя гонореи, применяемых в России и за рубежом: методе микроскопии, культуральном (бактериологическом) методе исследования, методах амплификации нуклеиновых кислот, технологии ДНК-чипов; в сравнительном аспекте отражены достоинства и недостатки каждого метода. Подчеркнуто, что основой диагностики гонореи в настоящее время является культуральный метод, обладающий высокой специфичностью и чувствительностью, позволяющий определять чувствительность N. gonorrhoeae к антимикробным препаратам, что особенно актуально ввиду возрастания в последние годы резистентности N. gonorrhoeae к антибиотикам. Методы амплификации нуклеиновых кислот и прежде всего полимеразная цепная реакция в России могут применяться в качестве скрининговых методов; результаты, полученные при использовании этих методов, требуют подтверждения культуральным методом

Determination of the parameters of semiconducting CdF2:In with Schottky barriers from radio-frequency measurements

Physical properties of semiconducting CdF_2 crystals doped with In are determined from measurements of the radio-frequency response of a sample with Schottky barriers at frequencies 10 - 10^6 Hz. The dc conductivity, the activation energy of the amphoteric impurity, and the total concentration of the active In ions in CdF_2 are found through an equivalent-circuit analysis of the frequency dependencies of the sample complex impedance at temperatures from 20 K to 300 K. Kinetic coefficients determining the thermally induced transitions between the deep and the shallow states of the In impurity and the barrier height between these states are obtained from the time-dependent radio-frequency response after illumination of the material. The results on the low-frequency conductivity in CdF_2:In are compared with submillimeter (10^{11} - 10^{12} Hz) measurements and with room-temperature infrared measurements of undoped CdF_2. The low-frequency impedance measurements of semiconductor samples with Schottky barriers are shown to be a good tool for investigation of the physical properties of semiconductors.Comment: 9 pages, 7 figure

The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron

The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The analysis of obtained preliminary data has shown that even about 2x10³ discharge pulses in H₂-N₂₃ mixture causes drastic decrease of partial hydrogen pressure and ultimate base pressure. But, in contrast, to revert initial high hydrogen partial pressure in the U-3M torsatron vacuum chamber, it is needed more than 2x10⁴ pulsed discharges in pure hydrogen. The possible reasons of effective hydrogen removing in RF-discharges in hydrogen-nitrogen mixtures are discussed.Досліджувався режим чищення імпульсними ВЧ-розрядами в суміші водню й азоту при концентраціях азоту від 4 at. % to 96 at. % при тих же параметрах ВЧ-генератора, що і для чистого водню. Аналіз отриманих даних показав, що вже близько 2x10³ імпульсів у H₂-N₂ суміші викликає помітне зниження парціального тиску водню і граничного тиску в камері У-3М. Навпроти, щоб повернути високий парціальний тиск водню у вакуумній камері У-3М необхідно більш ніж 2x10⁴ імпульсних розрядів у чистому водні. Обговорюються можливі причини ефективного видалення водню розрядами в суміші водню й азоту.Исследовался режим чистки импульсными ВЧ-разрядами в смеси водорода и азота при концентрациях азота от 4 at.% to 96 at.% при тех же параметрах ВЧ-генератора, что и для чистого водорода. Анализ полученных данных показал, что уже около 2x10³ импульсов в H₂-N₂ смеси вызывает заметное снижение парциального давления водорода и предельного давления в камере У-3М. Напротив, чтобы вернуть высокое парциальное давление водорода в вакуумной камере У-3М необходимо более чем 2x10⁴ импульсных разрядов в чистом водороде. Обсуждаются возможные причины эффективного удаления водорода разрядами в смеси водорода и азота

Space-time dynamics of low frequency plasma density fluctuations in URAGAN-3 torsatron

Experimentally investigated the space-time dynamics of low-frequency plasma density fluctuations for two regimes of discharges in torsatron U-3M and with laser-ablation-injection of carbon.Експериментально досліджена просторово-часова динаміка низько-частотних флуктуацій густини електронів у двох режимах розрядів та з лазерною інжекцією домішок вуглецю в торсатроні У-3М.Экспериментально исследована пространственно-временная динамика низко-частотных флуктуаций плотности электронов в двух режимах разрядов и с лазерной инжекцией примеси углерода в торсатроне У-3М

Self-optimization, community stability, and fluctuations in two individual-based models of biological coevolution

We compare and contrast the long-time dynamical properties of two individual-based models of biological coevolution. Selection occurs via multispecies, stochastic population dynamics with reproduction probabilities that depend nonlinearly on the population densities of all species resident in the community. New species are introduced through mutation. Both models are amenable to exact linear stability analysis, and we compare the analytic results with large-scale kinetic Monte Carlo simulations, obtaining the population size as a function of an average interspecies interaction strength. Over time, the models self-optimize through mutation and selection to approximately maximize a community fitness function, subject only to constraints internal to the particular model. If the interspecies interactions are randomly distributed on an interval including positive values, the system evolves toward self-sustaining, mutualistic communities. In contrast, for the predator-prey case the matrix of interactions is antisymmetric, and a nonzero population size must be sustained by an external resource. Time series of the diversity and population size for both models show approximate 1/f noise and power-law distributions for the lifetimes of communities and species. For the mutualistic model, these two lifetime distributions have the same exponent, while their exponents are different for the predator-prey model. The difference is probably due to greater resilience toward mass extinctions in the food-web like communities produced by the predator-prey model.Comment: 26 pages, 12 figures. Discussion of early-time dynamics added. J. Math. Biol., in pres

Reflection, radiation and interference for black holes

Black holes are capable of reflection: there is a finite probability for any particle that approaches the event horizon to bounce back. The albedo of the black hole depends on its temperature and the energy of the incoming particle. The reflection shares its physical origins with the Hawking process of radiation, both of them arise as consequences of the mixing of the incoming and outgoing waves that takes place on the event horizon.Comment: 10 pages, 1 figure, Revte

Quantum Inequalities for the Electromagnetic Field

A quantum inequality for the quantized electromagnetic field is developed for observers in static curved spacetimes. The quantum inequality derived is a generalized expression given by a mode function expansion of the four-vector potential, and the sampling function used to weight the energy integrals is left arbitrary up to the constraints that it be a positive, continuous function of unit area and that it decays at infinity. Examples of the quantum inequality are developed for Minkowski spacetime, Rindler spacetime and the Einstein closed universe.Comment: 19 pages, 1 table and 1 figure. RevTex styl