Knowledge of timing and extent of weed emergence before and immediately after crop seedbed preparation is needed to decrease need for preplant herbicides and increase efficacy of postemergence weed control in crops with either mechanical or chemical methods. Such knowledge is important for weeds that infest most crops over a wide area. For these reasons a mechanistic seedling emergence model based solely on soil temperature was developed for common lambsquarters. The model was validated using four sets of field data collected in 1988, 1990, and 1991 near Morris, MN. Agreement of predicted and observed emergence values across all site-years was 0.95 and the coefficient of determination (R2) was 0.98 (P < 0.001). Agreement for individual site-years was 0.96, 1.08, 1.08, and 0.98 and associated R2 values were 0.99, 0.99, 0.99, and 0.98 (P < 0.001 for each site-year), indicating close agreement between predicted and actual emergence values.

Nanoindentation techniques are commonly used to characterize nanomechanical properties of microscaled and nanoscaled materials. Nanoindentation using a cylindrical flat-tip indenter has a constant contact area which makes it a reliable source to find material’s yield strength as well as other mechanical properties. However, an angular misalignment of the indenter with the specimen results in experimental error. In this work, the effects of angular misalignment on the nanoindentation testing with a cylindrical flat-tip indenter were numerically analyzed. A three-dimensional nanoindentation solid model was generated, computer modeling based on finite element analysis was conducted. The angle of misalignment ranged from 0° to 1°. Young’s modulus and hardness were evaluated. Based on the hemispherical stress–strain distribution assumption of an elastic plastic indentation, corrected depths and modifiers were proposed for adjusting material’s 0.1% offset and 0.2% offset yield strengths. Low carbon steel AISI 1018 was selected as sample material for indentation testing and modeling validation.

A vascular corrosion cast of an entire mouse kidney was scanned with a modular multiresolution X-ray nanotomography system. Using an isotropic voxel pitch of 0.5 μm, capillary systems such as the vasa recta, peritubular capillaries and glomeruli were clearly resolved. This represents a considerable improvement over corrosion casts scanned with microcomputed tomography systems. The resolving power of this system was clearly demonstrated by the unique observation of a dense, subcapsular mat of capillaries enveloping the entire outer surface of the cortical region. Resolution of glomerular capillaries was comparable to similar models derived from laser scanning confocal microscopy. The high-resolution, large field of view and the three-dimensional nature of the resulting data opens new possibilities for the use of corrosion casting in research.

Corrosion-casted capillary systems of the kidney glomerulus were imaged with confocal microscopy because of the fluorescence properties of the casting plastic. Acquisition of a z-series through the glomerular capillaries provided three-dimensional data sets from which surface-rendered models were generated. These models could be rotated and viewed from any angle and also contained quantitative information allowing cast surface area and volume measurements to be calculated. The computer-generated models were also skeletonized to form a one-voxel-thick skeleton of the original model. The skeleton exhibited the three-dimensional topology and network of the capillary bed, and interior capillary relations could also be viewed. Quantitative information such as the total capillary length and number of capillary intersects was calculated from the skeletonized model. Extending this method to noncorroded kidney specimens revealed not only the casted vessels but also cellular features of the adjacent tissues surrounding the capillaries.

A novel three-dimensional model of tertiary interactions in the core region of the eukaryotic selenocysteine tRNA is proposed based on the analysis of available nucleotide sequences. The model features the 7/5 tRNASec secondary structure characterized by seven and five base pairs in the acceptor and T-stems, respectively, and four nucleotides in the connector region between the acceptor and D-stems. The model suggests a unique system of tertiary interactions in the area between the major groove of the D-stem and the first base pair of the extra arm that provides a rigid orientation of the extra arm and contributes to the overall stability of the molecule. The model is consistent with available experimental data on serylation, selenylation, and phosphorylation of different tRNASec mutants. The important similarity between the proposed model and the structure of the tRNASer is shown. Based on this similarity, the ability of some tRNASer mutants to be serylated, selenylated, and phosphorylated was evaluated and found to be in a good agreement with experimental data.