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Abstract—: The characteristics of the shape memory effect of a silicone rubber–titanium nickelide composite material under bending deformation have been studied. It is shown that the critical deformation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon _{{{\text{cr}}}}^{{0.2}}$$\end{document}), upon reaching which 0.2% of unrecoverable deformation is accumulated in the composite, can reach 36–38% (at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon _{{{\text{cr}}}}^{{0.2}}$$\end{document}= 9% in a reinforcing filler made of titanium nickelide). A method for calculating the mechanical behavior of a composite under bending deformation is proposed.

Abstract: In this paper, we study the effect of artificial aging modes on the structure, mechanical properties, and crack resistance of high-strength aluminum-lithium alloy V-1469 sheets. Kinetic curves of changes in mechanical properties at various temperatures and long exposures are plotted. To establish the possibility of increasing the crack resistance, one-stage and multistage modes of artificial aging are selected in the study. As a result, a mode that allows increasing crack resistance at a slight decrease in strength and maintaining high corrosion resistance and fatigue life is chosen. The structural-phase state and the complex of properties of sheets processed according to the selected mode with sheets processed according to the mode providing maximum strength are compared. Crack resistance determined for large-sized (750 mm wide) samples from V‑1469T1 alloy sheets processed according to the selected aging mode is at the level of plating sheets of alloy 1163AT. Unlike high-strength aluminum alloys with strength and fracture toughness achievable by overaging, the same properties in aluminum-lithium alloy V-1469 can be achieved by aging with short exposures.

The regularities of the effect of the variation in the chemical composition of the new Russian β‑solidifying TiAl-alloy (Ti–44.5 Al–2 V–1 Nb–2 Cr/1 Zr–(0–0.1) Gd, at %) within the chromium content from 1.5 to 2.5 at % (2.0–3.5 wt %) and zirconium from 0.5 to 1.5 at % (1.2–3.5 wt %), as well as the effect of gadolinium microalloying on the phase composition and the structure of ingots, have been studied. The ingots were obtained using double vacuum-arc remelting with the subsequent vacuum-induction melting and pouring of the melt into the steel chill mold at the melting-casting unit with a cold crucible. It is shown that 0.1 at % gadolinium microaddition results in a decrease in the average size of the macro grains from 3000 ± 500 μm to 400 ± 80 μm in the peripheral part of the ingots after the first remelting. It was found that the phase composition of TiAl-alloy compositions with Cr and Zr is represented by three main phases: γ-TiAl, α2-Ti3Al, and β-phase. The volume fraction of β-phase does not exceed 2–3% in ingots containing Zr, while it reaches 5–6% in ingots containing Cr. It was revealed that the microstructure of the ingots of all studied chemical compositions has a lamellar morphology. Sprouting of lamellar colonies through the grain boundaries was noted for ingots containing Zr.

Abstract—A composite material consisting of a silicone rubber matrix and nickel–titanium wire reinforcement added at different volume fractions is prepared, and its debond strength and thermomechanical behavior are studied. The debond strength of the composite can be increased by reducing the surface roughness of the embedded nickel–titanium wire to Ra= 0.16 μm. The loading rate has a considerable effect on the residual strain in this material. The composite materials with the reinforcement content of 10 to 31% subjected to a 10% pre-strain can fully recover their shape on heating, suggesting the presence of memory shape effect in these materials.

Abstract: The effect of excreta of earthworm species Aporrectodea caliginosa and Eisenia fetida on the mineralization of nitrogen compounds in soils has been studied. A single application of excreta obtained from three earthworms in one day increased the formation of nitrate nitrogen compounds in the soil by 10–50%. The application of ammonium nitrogen (in the form of NH4Cl) in amounts equivalent to the ammonium nitrogen content in the daily excreta of three earthworms had the same effect on the mineralization of nitrogen compounds. The effect of earthworm excreta, as well as the effect of ammonium nitrogen, on the nitrification process was an order of magnitude higher than their contribution to the formation of nitrates due to the oxidation of the introduced ammonium. Hence, ammonium—an important component of the earthworm excreta—can exert a stimulating effect on nitrification processes in the soil and produce long-term cumulative effects that are much more significant than the direct effect of this nitrogen compound.

Heparin was modified at carboxyl groups by reaction with several pharmacologically important amino-containing compounds in aqueous medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. In dependence on the nature of the amine and the ratio of reagents, conjugates containing 36–100% amide and 0–25% isoureidocarbonyl groups were synthesized. Isoureidoarylamide groups are present, along with amide moieties, in the products of heparin modification by hydroxyl-containing aromatic amines. The conjugate of heparin with p-aminobenzoic acid contained oligomeric arylamide.Heparin was modified at carboxyl groups by reaction with several pharmacologically important amino-containing compounds in aqueous medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. In dependence on the nature of the amine and the ratio of reagents, conjugates containing 36–100% amide and 0–25% isoureidocarbonyl groups were synthesized. Isoureidoarylamide groups are present, along with amide moieties, in the products of heparin modification by hydroxyl-containing aromatic amines. The conjugate of heparin with p-aminobenzoic acid contained oligomeric arylamide.

Before sensor-based variable rate technology (VRT) can be used to reduce nitrogen (N) fertilizer rates in winter wheat (Triticum aestivum L.) spectral radiance readings must be understood. One prominent issue is the impact of crop growth stage on spectral radiance readings, and the ensuing problem of relating databases gathered at different locations and different stages of growth. In order to evaluate the impact of growth stage on spectral radiance, sensor readings were taken from a winter wheat variety trial and two long-term N and phosphorus (P) fertility trials. The normalized difference vegetative index was computed using red and near infrared (NIR) spectral radiance measurements [NDVI=(NIR-red)/(NIR+red)]. TotalNuptake in winter wheat at Feekes growth stages 4, 5, 7, and 8 was highly correlated with NDVI. In the variety trial, non-significant differences in ND VI readings were noticed between the five common genotypes (by growth stage) grown in this region. However, slopes from linear regression of total N uptake on NDVI were different at different stages of growth, which suggests the need for growth stage specific calibration. Freeze injury (altered tissue color) affected the relationship between total N uptake and NDVI, however, NDVI continued to be a good predictor of in-season total N uptake in wheat even though cell blasting altered tissue color. This work showed that NDVI is a good predictor of biomass, but not necessarily total N concentration in plant tissue. The amount of variability in total N uptake as explained by NDVI increased with advancing growth stage (Feekes 4 to 7), largely due to an increased percentage of soil covered by vegetation.

Soil reflectance affects spectral irradiance measurements taken in winter wheat at early stages of growth when percent cover is low. The objective of this study was to determine the critical percent vegetation coverage needed for forage nitrogen (N) uptake calibration with indirect spectral irradiance measurements. Two field experiments were conducted at Tipton and Perkins, OK in October 1996. The effect of row spacing (15.2, 19.0, 25.4, and 30.5 cm) and growth stage (Feekes 4 and 5) under various N fertilizer rates (0, 56, 112, and 168 kg N ha-1) on spectral irradiance measurements from wheat was evaluated. The normalized difference vegetative index (NDVI) was used to characterize wheat canopy irradiance. In general, NDVI decreased with increasing row spacing and increased with N fertilizer rate at Feekes growth stage 4. Row spacing and N rate were independent of each other since no significant interaction was found. High correlation (r=0.81-0.98) was observed between NDVI and vegetation coverage. Percent vegetation coverage was a good predictor of the other dependent variables including forage dry matter, and total N uptake, which could indirectly be determined using NDVI. The coefficients of variation (CV's) from NDVI values decreased with increasing vegetation coverage suggesting that less variable NDVI values (CV less than 10%) might be obtained from plots where vegetation coverage exceeds 50%.

Abstract: Using clonal methods for assessment of hemopoietic and stromal cells and long-term bone marrow cell cultures, we have demonstrated heterogeneity of myelodysplastic syndrome. Low content of stromal precursor cells in native bone marrow, peculiarities in the formation of the stromal layer and its hemopoiesis-stimulating capacity in long-term cultures, and altered properties of stromal precursor cells in long-term cultures indicate defect in the stromal microenvironment in myelodysplastic syndrome.

No method exists to reliably predict percent vegetation coverage using indirect measures. This study was conducted to evaluate the use of digital image processing techniques applied to digital color, red-green-blue (RGB), images of crop canopies to estimate percent vegetation coverage and biomass. Two field experiments with winter wheat (Triticum aestivum L.) “Tonkawa”; were planted in October 1996 and 1997 at Perkins, OK on a Teller sandy loam (Udic Argiustoll) and at Tipton, OK on a Tipton silt loam (Pachic Argiustoll). Plot images from winter wheat canopies were taken using a Kodak DC40 Digital Camera (1995)1 with an image resolution of 756 × 504 pixels. Spectral irradiance readings were taken from wheat canopies in red (671±6 nm) and near infrared (780±6 nm) wavelengths, and normalized difference vegetation index (NDVI) was calculated. Percent vegetation coverage was estimated using image-processing routines in Micrografx Picture Publisher® version 7.0. The digital images were converted from 8-bit RGB tagged image file format (TIFF) files, which were produced by processing the images from the camera with Photo Enhancer®, to binary pseudo-color images. Percent of pixels corresponding to the vegetation color was then calculated and used as the percent coverage for each plot. Binary pseudo-color images provided useful estimates of percent vegetation coverage that were highly correlated with wheat canopy NDVI measurements.

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