156 research outputs found
DESIGNING A DIGITAL PLATFORM FOR ASSESSING THE PHYSICAL DEVELOPMENT OF CHILDREN IN THE EUROPEAN NORTH OF RUSSIA
This article discusses the prerequisites for creating a Web application that will automatically calculate basic anthropometric indicators of physical development and hemodynamic indices of children of the Arkhangelsk region
Determination of the Bending Rigidity of Graphene via Electrostatic Actuation of Buckled Membranes
The small mass and atomic-scale thickness of graphene membranes make them
highly suitable for nanoelectromechanical devices such as e.g. mass sensors,
high frequency resonators or memory elements. Although only atomically thick,
many of the mechanical properties of graphene membranes can be described by
classical continuum mechanics. An important parameter for predicting the
performance and linearity of graphene nanoelectromechanical devices as well as
for describing ripple formation and other properties such as electron
scattering mechanisms, is the bending rigidity, {\kappa}. In spite of the
importance of this parameter it has so far only been estimated indirectly for
monolayer graphene from the phonon spectrum of graphite, estimated from AFM
measurements or predicted from ab initio calculations or bond-order potential
models. Here, we employ a new approach to the experimental determination of
{\kappa} by exploiting the snap-through instability in pre-buckled graphene
membranes. We demonstrate the reproducible fabrication of convex buckled
graphene membranes by controlling the thermal stress during the fabrication
procedure and show the abrupt switching from convex to concave geometry that
occurs when electrostatic pressure is applied via an underlying gate electrode.
The bending rigidity of bilayer graphene membranes under ambient conditions was
determined to be eV. Monolayers have significantly lower
{\kappa} than bilayers
Effect of Laser Optoperforation of the Zona Pellucida on Mouse Embryo Development in vitro
Laser operations on cells and embryos are an important field of current photobiology and biophotonics. The high power density of tightly focused laser irradiation provides an efficient impact on matter of cells or embryos. Precise focusing of the laser spot allows strictly controlled perforation of the membrane. The present work was devoted to studying the influence of optoperforation of mammalian embryonic zona pellucida with a tightly focused laser beam with 1.48-µm wavelength on further development of the embryo. Such a laser operation was proposed for application in in vitro fertilization (IVF) practice and intracytoplasmic sperm injection into the oocyte (ICSI). For cultured in vitro oocytes and embryos, the process of natural exiting from the zona pellucida ("hatching") is often impaired, which decreases probability of implantation and pregnancy The goals of the present work were to determine the influence of different manipulations on development of embryos in vitro until blastocyst formation and on the ISSN 0006-2979, Biochemistry (Moscow), 2015, Vol. 80, No. 6, pp. 769-775. © Pleiades Publishing, Ltd., 2015. Original Russian Text © E. O. Zakharchenko, A. D. Zalessky, A. A. Osychenko, A. S. Krivokharchenko, A. K. Shakhbazyan, A. V. Ryabova, V. A. Nadtochenko, 2015, published in Biokhimiya, 2015 769 * To whom correspondence should be addressed. Abstract-The effect of laser optical perforation of the zona pellucida on the viability and development of mouse embryos has been studied. Operations of zona pellucida thinning and single or double perforation were carried out on 2-cell embryo, morula, and blastocyst stages with a laser pulse (wavelength 1.48 µm, pulse duration 2 ms). Embryo development up to the blastocyst stage and hatching efficiency were statistically analyzed. It was found that 2-cell or morula stage embryo zona pellucida thinning or single perforation did not affect development to the blastocyst stage and number of hatched embryos, but it accelerated embryo hatching compared to control groups one day earlier in vitro. Double optoperforation on 2-cell embryo or morula stage did not significantly affect development to the blastocyst stage, but it strongly decreased the number of hatched embryos. Also, zona pellucida perforation at the blastocyst stage had a negative effect: hatching did not occur after this manipulation. Blastocyst cell number calculation after single zona pellucida perforation at 2-cell and morula stages showed that cell number of hatching or hatched blastocysts did not differ from the same control groups. This fact points out that the laser single optoperforation method is a useful and safe experimental tool that allows further manipulations within the zona pellucida. Effect of Laser Optoperforation of the Zon
Technical and economic efficiency of the unconventional propulsion units use for civilian aircraft of various purposes
In order to develop a methodological apparatus for assessing various stages of the life cycle of hybrid/electric propulsion units, the existing approaches to estimating the costs of developing, manufacturing and operating aircraft engines of the traditional propulsion units scheme for determining the cost framework and their further harmonization with the technical and economic boundary conditions of new elements in the hybrid/electric SU scheme are considered. The relevance of solving the problems of assessing the technical and economic efficiency and forecasting the cost of hybrid propulsion units is determined. To solve the tasks, a methodological approach to determining boundary conditions and criteria is proposed. Within the framework of this methodological approach, a preliminary assessment of the cost of the main stages of the life cycle of aircraft engines for various variants of traditional propulsion units was made. Based on the estimates obtained, criteria for the economic efficiency of using a hybrid propulsion unit of various capacities for civil aircraft were formed. A computational and parametric analysis of the cost estimation of variants of aircraft engines included in the propulsion unit of the traditional scheme is presented. The role of accounting and management accounting data in economic and mathematical models is determined, which makes it possible to qualitatively reflect the economic efficiency of the life cycle of aviation products
Immunomodulating and Revascularizing Activity of Kalanchoe pinnata Synergize with Fungicide Activity of Biogenic Peptide Cecropin P1
© 2017 N. S. Zakharchenko et al. Previously transgenic Kalanchoe pinnata plants producing an antimicrobial peptide cecropin P1 (CecP1) have been reported. Now we report biological testing K. pinnata extracts containing CecP1 as a candidate drug for treatment of wounds infected with Candida albicans. The drug constitutes the whole juice from K. pinnata leaves (not ethanol extract) sterilized with nanofiltration. A microbicide activity of CecP1 against an animal fungal pathogen in vivo was demonstrated for the first time. However, a favorable therapeutic effect of the transgenic K. pinnata extract was attributed to a synergism between the fungicide activity of CecP1 and wound healing (antiscar), revascularizing, and immunomodulating effect of natural biologically active components of K. pinnata. A commercial fungicide preparation clotrimazole eliminated C. albicans cells within infected wounds in rats with efficiency comparable to CecP1-enriched K. pinnata extract. But in contrast to K. pinnata extract, clotrimazole did not exhibit neither wound healing activity nor remodeling of the scar matrix. Taken together, our results allow assumption that CecP1-enriched K. pinnata extracts should be considered as a candidate drug for treatment of dermatomycoses, wounds infected with fungi, and bedsores
Bactericide, Immunomodulating, and Wound Healing Properties of Transgenic Kalanchoe pinnata Synergize with Antimicrobial Peptide Cecropin P1 In Vivo
Procedure of manufacturing K. pinnata water extracts containing cecropin P1 (CecP1) from the formerly described transgenic plants is established. It included incubation of leaves at +4°C for 7 days, mechanical homogenization of leaves using water as extraction solvent, and heating at +70°C for inactivating plant enzymes. Yield of CecP1 (after heating and sterilizing filtration) was 0.3% of total protein in the extract. The water extract of K. pinnata + CecP1 exhibits favorable effect on healing of wounds infected with S. aureus (equal to Cefazolin) and with a combination of S. aureus with P. aeruginosa (better than Cefazolin). Wild-type K. pinnata extract exhibited evident microbicide activity against S. aureus with P. aeruginosa but it was substantially strengthened in K. pinnata + CecP1 extract. K. pinnata extracts (both wild-type and transgenic) did not exhibit general toxicity and accelerated wound recovery. Due to immunomodulating activity, wild-type K. pinnata extract accelerated granulation of the wound bed and marginal epithelialization even better than K. pinnata + CecP1 extract. Immunomodulating and microbicide activity of K. pinnata synergizes with microbicide activity of CecP1 accelerating elimination of bacteria
Ripple Texturing of Suspended Graphene Atomic Membranes
Graphene is the nature's thinnest elastic membrane, with exceptional
mechanical and electrical properties. We report the direct observation and
creation of one-dimensional (1D) and 2D periodic ripples in suspended graphene
sheets, using spontaneously and thermally induced longitudinal strains on
patterned substrates, with control over their orientations and wavelengths. We
also provide the first measurement of graphene's thermal expansion coefficient,
which is anomalously large and negative, ~ -7x10^-6 K^-1 at 300K. Our work
enables novel strain-based engineering of graphene devices.Comment: 15 pages, 4 figure
Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy
The thermal expansion coefficient (TEC) of single-layer graphene is estimated
with temperature-dependent Raman spectroscopy in the temperature range between
200 and 400 K. It is found to be strongly dependent on temperature but remains
negative in the whole temperature range, with a room temperature value of
-8.0x10^{-6} K^{-1}. The strain caused by the TEC mismatch between graphene and
the substrate plays a crucial role in determining the physical properties of
graphene, and hence its effect must be accounted for in the interpretation of
experimental data taken at cryogenic or elevated temperatures.Comment: 17 pagese, 3 figures, and supporting information (4 pages, 3
figures); Nano Letters, 201
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