ALBERT

Description: The spectral reflectance of crop canopy is a spectral mixture, which includes soil background as one of the components. However, as soil is characterized by substantial spatial variability and temporal dynamics, its contribution to the spectral reflectance of crops will also vary. The aim of the research was to determine the impact of soil background on spectral reflectance of crop canopy in visible and near-infrared parts of the spectrum at different stages of crop development and how the soil type factor and the dynamics of soil surface affect vegetation indices calculated for crop assessment. The study was conducted on three test plots with winter wheat located in the Tula region of Russia and occupied by three contrasting types of soil. During field trips, information was collected on the spectral reflectance of winter wheat crop canopy, winter wheat leaves, weeds and open soil surface for three phenological phases (tillering, shooting stage, milky ripeness). The assessment of the soil contribution to the spectral reflectance of winter wheat crop canopy was based on a linear spectral mixture model constructed from field data. This showed that the soil background effect is most pronounced in the regions of 350–500 nm and 620–690 nm. In the shooting stage, the contribution of the soil prevails in the 620–690 nm range of the spectrum and the phase of milky ripeness in the region of 350–500 nm. The minimum contribution at all stages of winter wheat development was observed at wavelengths longer than 750 nm. The degree of soil influence varies with soil type. Analysis of variance showed that normalized difference vegetation index (NDVI) was least affected by soil type factor, the influence of which was about 30%–50%, depending on the stage of winter wheat development. The influence of soil type on soil-adjusted vegetation index (SAVI) and enhanced vegetation index (EVI2) was approximately equal and varied from 60% (shooting phase) to 80% (tillering phase). According to the discriminant analysis, the ability of vegetation indices calculated for winter wheat crop canopy to distinguish between winter wheat crops growing on different soil types changed from the classification accuracy of 94.1% (EVI2) in the tillering stage to 75% (EVI2 and SAVI) in the shooting stage to 82.6% in the milky ripeness stage (EVI2, SAVI, NDVI). The range of the sensitivity of the vegetation indices to the soil background depended on soil type. The indices showed the greatest sensitivity on gray forest soil when the wheat was in the phase of milky ripeness, and on leached chernozem when the wheat was in the tillering phase. The observed patterns can be used to develop vegetation indices, invariant to second-type soil variations caused by soil type factor, which can be applied for the remote assessment of the state of winter wheat crops.

Description: Ti-based alloys are accessible for use in the human body due to their good mechanical properties, corrosion resistance, and biocompatibilities. These main properties of alloys are important criteria for choosing biomedical implants for human bones or for other kinds of applications in general medicine. This paper presents a comparison of four new Ti-based alloys desired to satisfy various requirements for biomedical implants. The materials were prepared with recipes for two new system alloys, TiMoZrTa (TMZT) and TiMoSi (TMS), alloys with nontoxic elements. The presented research contains microstructure images, indentation tests, Vickers hardness, XRD, and corrosion resistance, showing better characteristics than most commercial products used as implants (Young’s modulus closer to the human bone).

Description: Biochar has altered plant yields and soil nutrient availability in tropical soils, but less research exists involving biochar additions to temperate cropping systems. Of the existing research, results vary based on soil texture, crop grown, and biochar properties. The objective of this study was to determine the effects of pine (Pinus spp.) woodchip biochar at 0, 5, and 10 Mg·ha−1 rates combined with urea nitrogen (N) on soil chemical properties and corn (Zea mays L.) yield under field conditions in the first growing season after biochar addition in a silt-loam alluvial soil. Biochar combined with fertilizer numerically increased corn yields, while biochar alone numerically decreased corn yields, compared to a non-amended control. Corn nitrogen uptake efficiency (NUE) was greater with 10 Mg·ha−1 biochar compared to no biochar. There were limited biochar effects on soil nutrients, but biochar decreased nitrate, total dissolved N, and Mehlich-3 extractable sulfur and manganese concentrations in the top 10 cm. Pine woodchip biochar combined with N fertilizer has the potential to improve corn production when grown in silt-loam soil in the mid-southern U.S. by improving NUE and increasing yield. Further research will be important to determine impacts as biochar ages in the soil.

Description: Since soybean (Glycine max L. (Merr.)) yields greater than 6719 kg ha−1 have only recently and infrequently been achieved, little is known about the soil microbiological environment related to high-yield soybean production. Soil microbiological properties are often overlooked when assessing agronomic practices for optimal production. Therefore, a greater understanding is needed regarding how soil biological properties may differ between high- and average-yielding areas within fields. The objectives of this study were to (i) evaluate the effects of region on soil microbial carbon substrate utilization differences between high- (HY) and average-yield (AY) areas and (ii) assess the effect of yield area on selected microbiological property differences. Replicate soil samples were collected from the 0–10 cm depth from yield-contest-entered fields in close proximity that had both a HY and an AY area. Samples were collected immediately prior to or just after soybean harvest in 2014 and 2015 from each of seven geographic regions within Arkansas. Averaged across yield area, community-level carbon substrate utilization and Shannon’s and Simpson’s functional diversity and evenness were greater (p 〈 0.05) in Region 7 than all other regions. Averaged across regions, Shannon’s functional diversity and evenness were greater (p 〈 0.05) in HY than in AY areas. Principal component analysis demonstrated that a greater variety of carbon substrates were used in HY than AY areas. These results may help producers understand the soil microbiological environment in their own fields that contribute to or hinder achieving high-yielding soybeans; however, additional parameters may need to be assessed for a more comprehensive understanding of the soil environment that is associated with high-yielding soybean.

Description: In this paper, optimality conditions are studied for a new class of PDE and PDI-constrained scalar variational control problems governed by path-independent curvilinear integral functionals. More precisely, we formulate and prove a minimal criterion for a local optimal solution of the considered PDE and PDI-constrained variational control problem to be its global optimal solution. The effectiveness of the main result is validated by a two-dimensional non-convex scalar variational control problem.

Description: Carbon nanotubes (CNTs) have record high tensile strength and Young’s modulus, which makes them ideal for making super strong yarns, ropes, fillers for composites, solid lubricants, etc. The mechanical properties of CNT bundles have been addressed in a number of experimental and theoretical studies. The development of efficient computational methods for solving this problem is an important step in the design of new CNT-based materials. In the present study, an atomistic chain model is proposed to analyze the mechanical response of CNT bundles under plane strain conditions. The model takes into account the tensile and bending rigidity of the CNT wall, as well as the van der Waals interactions between walls. Due to the discrete character of the model, it is able to describe large curvature of the CNT wall and the fracture of the walls at very high pressures, where both of these problems are difficult to address in frame of continuum mechanics models. As an example, equilibrium structures of CNT crystal under biaxial, strain controlled loading are obtained and their thermal stability is analyzed. The obtained results agree well with previously reported data. In addition, a new equilibrium structure with four SNTs in a translational cell is reported. The model offered here can be applied with great efficiency to the analysis of the mechanical properties of CNT bundles composed of single-walled or multi-walled CNTs under plane strain conditions due to considerable reduction in the number of degrees of freedom.