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Abstract.  “Almost quasistationary” approximation is suggested for the investigation of the problem of solidification front stability. It is appropriate for the initial stage of the process when sizes of particles are sufficiently small. The cases of “sphere like” and “cylinder-like” nuclei are considered. Capillary forces are taken into account. [ABSTRACT FROM AUTHOR]

It is known that for every Banach space $X$ and every proper $WOT$-closed subalgebra $mathcal A$ of $L(X)$, if $mathcal A$ contains a compact operator, then it is not transitive; that is, there exist non-zero $xin X$ and $fin X^*$ such that $langle f,Txrangle =0$ for all $Tin mathcal A$. In the case of algebras of adjoint operators on a dual Banach space, V. Lomonosov extended this result as follows: without having a compact operator in the algebra, one has $bigl lvert langle f,Txrangle bigr rvert le lVert T_*rVert _e$ for all $Tin mathcal A$. In this paper, we prove a similar extension of a result of R. Drnovsek. Specifically, we prove that if $mathcal C$ is a collection of positive adjoint operators on a Banach lattice $X$ satisfying certain conditions, then there exist non-zero $xin X_+$ and $fin X^*_+$ such that $langle f,Txrangle le lVert T_*rVert _e$ for all $Tin mathcal C$. [ABSTRACT FROM AUTHOR]

Abstract   Background: To investigate the activity and toxicity of high dose (HD) infusional 5-FU in comparison to EAP regimen as first-line chemotherapy in patients with advanced gastric cancer. Patients and methods: Histologically confirmed measurable advanced gastric cancer, age 2), etoposide (360 mg/m2), and cisplatin (80 mg/m2) every 28 d; HD 5-FU arm: 5-FU 2.6 g/m2 24 h infusion, biweekly. Results: Sixty patients were randomized. Patient characteristics (arms EAP/HD 5-FU): Median age 57/55 yr, median PS 1/1, LAD (patients) 3/8, M1 (patients) 27/22. Median number of cycles (range): EAP arm 4 (2–8), HD 5-FU arm 2 (1–8). Worst toxicity per cycle (grade 3 and 4 in%): Neutropenia 20/3, thrombocytopenia 9/0, anemia 9/13, diarrhea 3/10, nausea 17/7, vomiting 10/0 for EAP and HD 5-FU arms, respectively. All patients were eligible for response in both arms. Confirmed response rate (95%CI): EAP arm 34% [16–50%]/HD 5-FU arm 10% (0–21%), no change: 46/40%, progression of disease: 20/50, respectively. Overall survival (range): EAP arm A 7 mo [3–27], HD 5-FU arm 6 mo (4–25). Conclusions: Infusional HD 5-FU showed a low incidence of severe toxicity. But given the low efficacy of 5-FU in the dosage we applied in the study, it cannot be recommended as a single treatment for further studies. Assessment of higher dose intensity and/or dose density of 5-FU, with introduction of other active drugs in combination, could be an option for further studies. [ABSTRACT FROM AUTHOR]

Abstract  Models of the formation of nanorolls in fluid media are constructed. The successive stages of the detachment of a stressed double nanolayer with the subsequent twisting into a nanoroll are calculated by the molecular dynamics method. The dynamics of twisting with the formation of a multiwalled nanoroll is described within a continuous model. The results of simulating the formation of different configurations of nanorolls during their diffusion growth are reported. [ABSTRACT FROM AUTHOR]

Abstract Published data are reviewed along with our own data on synaptic plasticity and rearrangements of synaptic organelles in the central nervous system. Contemporary laser scanning and confocal microscopy techniques are discussed, along with the use of serial ultrathin sections for in vivo and in vitro studies of dendritic spines, including those addressing relationships between morphological changes and the efficiency of synaptic transmission, especially in conditions of the long-term potentiation model. Different categories of dendritic spines and postsynaptic densities are analyzed, as are the roles of filopodia in originating spines. The role of serial ultrathin sections for unbiased quantitative stereological analysis and three-dimensional reconstruction is assessed. The authors data on the formation of more than two synapses on single mushroom spines on neurons in hippocampal field CA1 are discussed. Analysis of these data provides evidence for new paradigms in both the organization and functioning of synapses. [ABSTRACT FROM AUTHOR]

An amplification scheme for ultrashort laser pulses of high radiation contrast was used to perform experiments on ablation pressure symmetrization using a prepulse upon acceleration of thin foils. It is shown that the spontaneous radiation of the regenerative amplifier restricts the energy contrast in the amplification of chirped pulses at a level of 10-4–10-3. The possibility of direct amplification of a short pulse with a view to increasing the energy contrast ratio was considered. Experiments were performed on the “PICO” laser facility to demonstrate that a 10-ps pulse amplification achieved an intensity ≥100 GW/cm2, a gain factor of 1.2, and an inversion dumping factor >30%. [ABSTRACT FROM AUTHOR]

Reflection and structural analyses of different copper and zinc coatings were performed. The copper coatings were electrodeposited from a sulfate solution in the presence of thiourea, as well as in the presence of modified polyglycol ether, PEG 6000 and 3-mercaptopropanesulfonate. The zinc coating was electrodeposited from a sulfate solution in the presence of a dextrin/salicylaldehyde mixture. They were examined by STM and X-ray diffraction analysis, and measurements of the reflection of light from their surfaces were taken. The mean sizes of atomically flat parts of these surfaces were estimated by the STM software measurements, using options for the determination of the autocovariance function and the power spectral density function. It was shown that the mean sizes of atomically flat parts of the copper coatings were several times greater than the mean size of atomically flat parts of the zinc coating. This difference probably leads to the difference in the maximum degrees of mirror reflection between copper and zinc coatings. [ABSTRACT FROM AUTHOR]

Evidence for morphological substrates of long-term changes in synaptic efficacy is controversial, partly because it is difficult to employ an unambiguous control. We have used a high-frequency stimulation protocol in vivo to induce long-term potentiation (LTP) in the hippocampal dentate gyrus of aged (22-month-old) rats and have found a clear distinction between animals that sustain LTP and those that fail to sustain it. The “failure group” was used as a specific/“like-with-like” control for morphological changes associated with the expression of LTP per se. Quantitative optical and electron microscopy was used to analyze large populations of dendritic spines and excitatory perforant path synapses; LTP was found to be associated with an increase in numbers of segmented (perforated) postsynaptic densities in spine synapses. In contrast, an increase in the number of branched spines appears to result from high-frequency stimulation alone. These data shed light on the current controversy about the expression mechanism of LTP. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

From the pulse rate curve taken during exercise and recovery from highly qualified sportsmen performing a bicycle exercise test at a maximum workload, the work pulse sum, pulse debt, and pulse cost were calculated. Plots of these indices versus the time to exhaustion and versus the relative exercise workload were identical to the respective plots of oxygen consumption during exercise, oxygen debt, and oxygen requirement. The exercise pulse cost can serve as a criterion for quantifying physical workloads. [ABSTRACT FROM AUTHOR]

Two-dimensional materials such as hexagonal boron nitride (h-BN) and graphene have attracted wide attention in nanoelectronics and spintronics. Since their electronic characteristics are strongly affected by the local atomic structure, the heteroatom doping could allow us to tailor the electronic and physical properties of two-dimensional materials. In this study, a non-chemical method of heteroatom doping into h-BN under high-energy ion irradiation was demonstrated for the LiF/h-BN/Cu heterostructure. Spectroscopic analysis of chemical states on the relevant atoms revealed that 6% ± 2% fluorinated h-BN is obtained by the irradiation of 2.4 MeV Cu2+ ions with the fluence up to 1014 ions cm−2. It was shown that the high-energy ion irradiation leads to a single-sided fluorination of h-BN by the formation of the fluorinated sp3-hybridized BN. [ABSTRACT FROM AUTHOR]

Electronic spectra of arylaminoanthraquinones and their amidinium salts in acids were studied, and experimental data on electrophilic substitution of diarylaminoanthraquinone amidinium salts in acetic and sulfuric acids of various concentrations were considered. [ABSTRACT FROM AUTHOR]

Aqueous solutions containing thallium(III) and diethylenetriaminopentakis(methylenephosphonic acid) (DTPP, H10Dtpph) in a ratio of 1 : 1 were studied by 31P NMR spectroscopy in a pH range from 4 to 11. Complexation between DTPP and thallium in aqueous solutions gave complexes [TlHnDtpph]n – 7, which are highly stable on the NMR time scale. Each complex contains three nonequivalent phosphonic groups characterized by 2,3J(31Р,Tl) spin–spin coupling constants of 560 to 310 Hz. All the five phosphonic groups of DTPP are involved in coordination. The structure of the complex [TlHnDtpph]n – 7 was proposed. [ABSTRACT FROM AUTHOR]

The effect of treatment in nitrogen plasma on the properties of partially reduced graphene oxide (rGO) was studied. A comparison is made between two different sample locations in the reaction chamber. It is shown that in the case when rGO films were turned towards the inductor of the plasma system, the etching rate is much higher. Effective nitrogen functionalization of rGO was established in the second position, when the rGO films were turned in the opposite direction. In this case, the nitrogen content increases to 5 at% of the initial value. The change in the current–voltage characteristics is observed under illumination, which is independent of the wavelength. On and off daylight changes the resistance to 30% of the initial value. The magnitude of the photocurrent increases depending on the applied voltage. The effect is most noticeable for thin rGO films 10–15 nm in thickness. [ABSTRACT FROM AUTHOR]

The response of a graphene-based humidity sensor is considered as a function of film structures. Analysis of the resistance changes due to water molecule adsorption on the graphene or multi-layer graphene (MLG) surface is performed for films with different structures and resistivities from hundreds of ohms/sq to hundreds of kilo-ohms/sq. The results revealed possible increase, decrease and non-monotonous behavior of resistance with changes in film structure. Adsorption of water molecules at grain boundary defects is assumed to lead to an increase in film resistivity due to the donor property of water and the p-type conductivity of graphene. Another type of conductive center with a higher capture cross-section is realized in the case of water molecule adsorption at edge defects in MLG films (the formation of conductive chains with ionic conductivity). If these chains form a continuous network the film resistivity decreases. The result of the competition between the opposite effects of the conductivity compensation and formation of the water-based conductive chains depends on the film structure and determines the response of humidity sensors. Sensor sensitivity is found to increase when only one type of defect determines water adsorption (edge defects or grain boundary defects). [ABSTRACT FROM AUTHOR]