Influence of surface topography on the multilayer film formation

The relationship between the topography of substrates and multilayer films deposited on these substrates (which are used in ring laser gyroscopes) has been investigated. The surfaces were studied by atomic-force microscopy. The statistical properties of the surface topography are analyzed within the approach based on a comparative analysis of the power spectral density functions of roughness calculated for the substrate and film. The degree of correlation between the substrate nanotopography and multilayer film is determined, and the influence of the substrate roughness on the optical characteristics of the deposited mirrors is established.     

Optical properties of one-dimensional subwave plasmonic nanostructures

Nanogratings formed by parallel gold nanowires on a quartz substrate have been fabricated. Their transmission and reflection spectra have been studied experimentally. Numerical simulation of the transmission (reflection) spectra has been performed. The simulated spectra agree well with the experimental ones. A package has been proposed, which combines the experimental techniques of the structure fabrication and theoretical methods for calculating the parameters of optical spectra. This package is a promising tool for designing and fabricating optoelectronic devices such as filters, polarizers, and switches.     

Nanobiocomposites of noble metals based on arabinogalactan: Preparation and properties

A simple general method employing arabinogalactan hemicellulose as a reducing and stabilizing agent is used to synthesize hydrophilic nanoparticles of noble metals. The prepared organic-inorganic nanobiocomposites are characterized by electronic spectroscopy, powder X-ray diffraction, and scanning electron microscopy. The sizes of coherent scattering regions of the metal phase of the prepared nanocomposites are determined, and their surface morphology and grain size are demonstrated to be controlled by the nature of the nanosized metal.     

Barothermal Diels-Alder functionalization of multi-walled carbon nanotubes

Abstract

Multi-walled carbon nanotubes (MWCNTs) have an ordered geometric structure, large specific surface area, prominent electrical conductivity, and unique mechanical properties. They are nontoxic and can be used in biomedicine. Physical and surface chemical characteristics of MWCNTs should be tuned to that required to improve certain properties and obtain a variety of functional materials. We modified the MWNTs by using the barothermal Diels-Alder reaction with dienophiles, p-benzoquinone, fumaronitrile, and maleimide, to address this issue. The prepared MWCNTs were studied by SEM-EDX, nitrogen adsorption porometry, ATR FTIR, and thermal analysis. Results showed that both separate and conjugated C?=?C bonds at the edge and outer/inner surface of walls could react with dienophiles. The grafted groups are separated by the temperature on weak (low-temperature) and strong (high-temperature) chemisorbed forms; they are detached at temperatures below and above 350?°C, correspondingly. Thermal analysis shows that up to 5% of the carbon atoms are involved in the [4?+?2] cycloaddition. The high-temperature forms of the grafted groups under extreme heating can be involved in the retro-Diels-Alder reaction that breaks six-membered rings, producing a dienophile.     

Kinetics of the dehydration of 2-propanol on modified activated charcoal containing acid sites

A study was carried out on the kinetics of the dehydration of 2-propanol on activated bone charcoal (ABC) with supported acid sites. The rate-limiting step is the loss of water from the alcohol molecule adsorbed on the acid site. The sites containing the minimum amount of water are the most active. The reaction on these sites presumably proceeds through a concerted mechanism, which is possible at sufficiently high temperatures (above 120 °C). Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 5, pp. 321–327, September–October, 2008.     

Design of a molecular-beam reflector yielding a uniform distribution of condensate over the plane of its cross section

In certain cases it is advantageous to use a molecular-beam reflector, when a uniform distribution of condensate over a large substrate surface is desired with a maximum economy of the evaporated substance. The authors propose and analyze here a computer-aided design of the reflector geometry, a hollow solid of revolution, to yield a uniform distrltution of condensate over the plane of its cross section. A digital-computer program has been set up which follows the steps of the solution process and designed for calculating the reflector geometry on the basis of the Maxwell-Millikan coefficient for incidence and reflection of a molecular beam at angles within 2π.     

The phosphorylation of carboxylic acids and amino acids by diseryl pyrophosphates

Summary 1. From the reaction of chymotrypsin with the NPE of CBZ-L- and CBZ-D-valine the enzyme-substrate compounds CBZ-L-valylchymotrypsin and CBZ-D-valylchymotrypsin have been isolated. The methyl esters of benzoyl-D-phenylalanine and of benzoyl-L-valine also form enzyme-substrate compounds with chymotrypsin, although to a smaller extent. The methyl ester of benzoyl-D-valine does not react with chymotrypsin.2. Conditions for the isolation of a water-soluble enzyme-substrate compound have been found.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 2, pp. 134–138, 1966Given at the First All-Union Biochemical Congress, 25 January 1964 (Leningrad).