Unfolding and unzipping of single-stranded DNA by stretching

We present a theoretical study of single-stranded DNA under stretching. Within the proposed framework, the effects of basepairing on the mechanical response of the molecule can be studied in combination with an arbitrary underlying model of chain elasticity. In a generic case, we show that the stretching curve of ssDNA exhibits two distinct features: the second-order "unfolding" phase transition, and a sharp crossover, reminiscent of the first-order "unzipping" transition in dsDNA. We apply the theory to the particular cases of Worm-like Chain (WLC) and Freely-Joint Chain (FJC) models, and discuss the universal and model--dependent features of the mechanical response of ssDNA. In particular, we show that variation of the width of the unzipping crossover with interaction strength is very sensitive to the energetics of hairpin loops. This opens a new way of testing the elastic properties of ssDNA.Comment: 7 pages, 4 figures, substantially revised versio

Особливості морфології личинок звичайної землянки Pelobates fuscus (Laurenti, 1768) з територій Волинського та Чернігівського Полісся

Исследована морфология личинок обыкновенной чесночницы, обитающей на территориях Волынского и Черниговского Полесья, с момента массового выхода из оболочек до завершения метаморфоза. Изучено строение присоски, развитие ротового аппарата, изменения линейных параметров. Выяснено, что строение присоски, ротового аппарата, изменения линейных параметров личинок обыкновенной чесночницы из популяций Волынского и Черниговского Полесья не имеют существенных отличий. Досліджено морфологію личинок звичайної землянки, що мешкає на територіях Волинського та Чернігівського Полісся, з моменту масового виходу з оболонок до завершення метаморфозу. Вивчено будову присоска, розвиток ротового апарату, зміни лінійних параметрів. З’ясовано, що будова присоска, ротового апарату, зміни лінійних параметрів личинок звичайної землянки з популяцій Волинського та Чернігівського Полісся не мають істотних відмінностей. The article treats off the morphology of the larvae of Common Spadefoot Toad inhabiting Volyn and Chernihiv Polissia. The span of analysis extended from the moment of their mass leaving the jelly envelopes up to the end of metamorphosis. The article studies the structure of the sucker and mouthparts, dynamics of larvae’s linear parameters. The achieved results testify to the absence of significant differences in the said species’ larvae’s structure of the sucker and mouthparts, as well as their linear parameters’ dynamics.Работа выполнена на кафедре экологии и охраны природы ЧНПУ им. Т. Г. Шевченк

Materials and Methods of the Study of Influence of Agrotechnical Methods on Sensory Characteristics of Technical Sorts of Grape

The topicality of using the sensory analysis of berries in enological practice at planning of agrotechnical complex at vineyard to receive the certain style and quality of production was grounded. For study of the influence of agrotechnical methods on sensory characteristics of technical sorts of grape Zagrey and Fragrant, selected by NSC “IVaW named after V.E. Tairov” (Ukraine), there was elaborated the algorithm of research, including field experiment and laboratory sensory analysis. The method of organoleptic analysis of berries, consisted of 20 parameters for assessment of visual, tactile and gustatory properties of pulp, peel and seeds, was approbated. Mathematical processing of experimental data was carried out by the methods of one- and two-factor analysis of variance and analysis of main components in the environment of package of applied programs MS Excell 2010, Statistica Statsoft ver. 7. 0 (Tulsa, USA).The sensory descriptors, characterizing the quality of studied sorts of grape, were determined. It was established, that agrotechnical methods of planting grape bushes influenced the sensory characteristics of berries of studied sorts

A study of cell membranes in nasal epithelial cells from patients with chronic rhinosinusitis with nasal polyps by means of a fluorescent probe

Aim. To assess the state of membranes in nasal epithelial cells obtained from the patients with chronic rhinosinusitis with nasal polyps (CRSwNP) with the help of the fluorescent probe 2-(2ʹ-ОН-phenyl)-5-phenyl-1,3-oxazole. Methods. The state of membrane phospholipid bilayer in suspensions of nasal epithelial cells isolated from ten patients with CRSwNP was evaluated using the fluorescent probe 2-(2ʹ-ОН-phenyl)-5-phenyl-1,3-oxazole that reacts on the physico-chemical properties of its microenvironment. Changes in fluorescence spectra were determined using a Thermo Scientific Lumina fluorescence spectrometer (Thermo Fisher Scientific) 1 hour after the addition of the probe to nasal epithelial cell suspensions. Results. CRSwNP was found to be associated with a higher rate of nasal epithelial cell membrane hydration in the region of phospholipid glycerol moiety, carbonyl groups and aliphatic chains of fatty acids attached to the carbonyl groups. Conclusion. Our findings suggest that CRSwNP is accompanied by the elevated hydration rate of the most polar region, namely polar heads of phospholipids of nasal epithelial cell membranes

Coulomb Charging Effects in an Open Quantum Dot

Low-temperature transport properties of a lateral quantum dot formed by overlaying finger gates in a clean one-dimensional channel are investigated. Continuous and periodic oscillations superimposed upon ballistic conductance steps are observed, when the conductance G of the dot changes within a wide range 0<G<6e^2/h. Calculations of the electrostatics confirm that the measured periodic conductance oscillations correspond to successive change of the total charge of the dot by $e$. By modelling the transport it is shown that the progression of the Coulomb oscillations into the region G>2e^2/h may be due to suppression of inter-1D-subband scattering. Fully transmitted subbands contribute to coherent background of conductance, while sequential tunneling via weakly transmitted subbands leads to Coulomb charging of the dot.Comment: 12 pages, RevTeX, 15 eps figures included, submitted to Phys. Rev.

Vortices in Spatially Inhomogeneous Superfluids

We study vortices in a radially inhomogeneous superfluid, as realized by a trapped degenerate Bose gas in a uniaxially symmetric potential. We show that, in contrast to a homogeneous superfluid, an off-axis vortex corresponds to an anisotropic superflow whose profile strongly depends on the distance to the trap axis. One consequence of this superflow anisotropy is vortex precession about the trap axis in the absence of an imposed rotation. In the complementary regime of a finite prescribed rotation, we compute the minimum-energy vortex density, showing that in the rapid-rotation limit it is extremely uniform, despite a strongly inhomogeneous (nearly) Thomas-Fermi condensate density $\rho_s(r)$. The weak radially-dependent contribution ($\propto \nabla^2\ln\rho_s(r)$) to the vortex distribution, that vanishes with the number of vortices $N_v$ as $\frac{1}{N_v}$, arises from the interplay between vortex quantum discretness (namely their inability to faithfully support the imposed rigid-body rotation) and the inhomogeneous superfluid density. This leads to an enhancement of the vortex density at the center of a typical concave trap, a prediction that is in quantitative agreement with recent experiments (cond-mat/0405240). One striking consequence of the inhomogeneous vortex distribution is an azimuthally-directed, radially-shearing superflow.Comment: 22 RevTeX pages, 20 figures, Submitted to PR

Influence of the modifying agent nano-powder of nickel on basic electrophysical characteristics of polyvinylidene fluoride

Results of the study of temperature-frequency relationships of dielectric permittivity and dielectric loss tangent, electric strength and permolecular structure of polyvinylidene fluoride, modified nano-powder of nickel are presented in this paper. It was shown that load nano-particles of nickel in polyvinylidene fluoride lead to change of structure and electrophysical characteristics one