DNA-polymer complexes for gene therapy

The condensation of DNA induced by vinyl saccharide graft copolymers of N-methacryloy-lamino-D-glucose with N,N-dimethylaminoethyl methacrylate and N-vinylpyrrolidone with N-vinylamine and induced by the linear polycation poly(L-lysine) in solution, as well as the conformational changes of a DNA molecule during its interaction with polycations in solution, is studied by atomic-force microscopy, low-gradient viscometry, dynamic birefringence, spectrophotometry, circular dichroism, and electrophoresis. The differences in the conformational changes of DNA related to the effect of polycations and other agents inducing its condensation are discussed.     

Material properties and fire test results

Five material properties commonly used to describe the fire behavior of solids were evaluated as sole explanatory variables for four small‐scale fire tests with pass/fail outcomes by using a physically based probabilistic (phlogistic) burning model. The phlogistic model describes the likelihood of passing vertical Bunsen burner tests and a regulatory heat release rate test reasonably well over a wide range of material properties, as deduced from the correlation coefficient and mean deviation of the predicted and measured values. Of the thermal, combustion, and fire properties examined, the best predictors of the likelihood of passing the fire tests of this study were the heat of combustion of the sample, the heat release capacity, and the heat release parameter. The relative merits and drawbacks of qualitative (threshold) and quantitative (probabilistic) approaches to predicting fire test results using thermal and combustion properties are discussed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Thermal analysis of polymer ignition

Gas phase criteria for the onset of flaming combustion of solids in fires are used to locate a critical temperature T_cr in a nonisothermal analysis (TA) experiment that corresponds to the surface temperature of the solid at ignition in a fire test, T_ign. This critical TA temperature occurs at low conversion of solid to gaseous fuel so it is independent of the heating rate in the test or the thermal decomposition reaction model. However, T_cr depends on the thermal properties of the polymer and the conditions of the fire test in which the gas phase criteria were measured. Nonisothermal analysis data in nitrogen and air were obtained for 20 polymers by thermogravimetric analysis and microscale combustion calorimetry. The critical temperatures T_crs obtained from TA experiments compared favorably with analytic results for a simple polymer ignition model and finite element simulations and were in qualitative agreement with ignition temperatures measured in standardized fire tests.     

Hyaluronan/Diethylaminoethyl Chitosan Polyelectrolyte Complexes as Carriers for Improved Colistin Delivery

Improving the therapeutic characteristics of antibiotics is an effective strategy for controlling the growth of multidrug-resistant Gram-negative microorganisms. The purpose of this study was to develop a colistin (CT) delivery system based on hyaluronic acid (HA) and the water-soluble cationic chitosan derivative, diethylaminoethyl chitosan (DEAECS). The CT delivery system was a polyelectrolyte complex (PEC) obtained by interpolymeric interactions between the HA polyanion and the DEAECS polycation, with simultaneous inclusion of positively charged CT molecules into the resulting complex. The developed PEC had a hydrodynamic diameter of 210–250 nm and a negative surface charge (ζ-potential = −19 mV); the encapsulation and loading efficiencies were 100 and 16.7%, respectively. The developed CT delivery systems were characterized by modified release (30–40% and 85–90% of CT released in 15 and 60 min, respectively) compared to pure CT (100% CT released in 15 min). In vitro experiments showed that the encapsulation of CT in polysaccharide carriers did not reduce its antimicrobial activity, as the minimum inhibitory concentrations against Pseudomonas aeruginosa of both encapsulated CT and pure CT were 1 μg/mL.     

Low-cost spectroscopy with a variable multivariate optical element

Here, successful realization of a variable multivariate optical element (VMOE) based on a transmissive liquid crystal (LC) panel is reported. In contrast to conventional multivariate optical elements (MOEs), a single VMOE is a dynamic system, allowing measurement of numerous analytes in different mixtures. Furthermore, VMOE has superior spectral resolution in comparison to a conventional MOE. It is demonstrated here that the system implemented in a Raman spectrometer predicts the concentration of each individual component in toluene-acetonitrile-cyclohexane mixtures with a prediction error of <6% (mass percentage). With a dedicated optical design of the setup, a prediction error smaller than 2% is expected to be feasible for the current chemical system.     

The Two-Circuit Parametric Amplifier of the Range 60–65 GHz

In present work the results of research of the not cooled parametric amplifier with little noise intended for use as the input stage of receiving devices of the range 60–65 GHz are given. The dynamic characteristics of oscillatory system that has as filters and circuits of signal and idle frequency the dielectric inserts and expansion in signal plumbing are investigated. The experimental results of research of amplifier models executed on BDS without package are given. Factor of amplification is 15 dB, temperature of noise - 550 - 600 ⁰ K.     

Conformational changes of a DNA molecule induced by metal complexes formed in solution

Changes in the tertiary structure of a high-molecular-mass DNA in solution that result from the addition of trivalent lanthanum ions, including intramolecular structuring of the macromolecule, are studied by atomic-force microscopy. The effect of bivalent magnesium and manganese ions on the structure of DNA in an aqueous-alcohol solution is analyzed. The data are compared with the results of viscometry, dynamic light scattering, flow birefringence, circular dichroism, and UV spectrophotometry.     

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer （LDV）.     

Geometry of Contact Metal-Semimetal BiSb Influence on Their Voltwatt Sensitivity in MM Range

Contact phenomena's studying is one of the most important physics and solid state department that has great applied significance. All modern solid state electronics based on use contact phenomena's in various junctions- electron-hole, metal-semiconductor etc. In recent time the class of solid state as semimetal which typical representatives are bismuth, antimony and its alloys is rather good searched. Special interest is the current traverse through small area metal-semimetal contact processes in connection with such contact may be used for detecting HF signals and measuring of small levels continuous and pulse UHF power as in centimeter as in millimeter wave length range [1,2\. One of the main characteristic of electromagnetic radiation detectors based on metal-semimetal BiSb contact is volt-watt sensitivity.     

The effect of variation in polymer properties on the rate of burning

The sensitivity of the burning rate to variations in physical and chemical properties of synthetic polymers has been examined in order to understand the relative importance of the knowledge of these properties. The sensitivity analysis was performed using a numerical pyrolysis model called ThermaKin, which was employed to compute the rate of burning (expressed in terms of mass loss) of a one‐dimensional material object exposed to steady radiative heat. The results of the calculations indicate that the knowledge of decomposition reaction parameters (including the Arrhenius pre‐exponential factor, activation energy, heat, and char yield) is of key importance for prediction of the peak and average burning rates. Copyright © 2009 John Wiley & Sons, Ltd.