Rice (Oryza sativa L.) is a chilling-sensitive staple crop that originated in subtropical regions of Asia. Introduction of the chilling tolerance trait enables the expansion of rice cultivation to temperate regions. Here we report the cloning and characterization of HAN1, a quantitative trait locus (QTL) that confers chilling tolerance on temperate japonica rice. HAN1 encodes an oxidase that catalyzes the conversion of biologically active jasmonoyl-L-isoleucine (JA-Ile) to the inactive form 12-hydroxy-JA-Ile (12OH-JA-Ile) and fine-tunes the JA-mediated chilling response. Natural variants in HAN1 diverged between indica and japonica rice during domestication. A specific allele from temperate japonica rice, which gained a putative MYB cis-element in the promoter of HAN1 during the divergence of the two japonica ecotypes, enhances the chilling tolerance of temperate japonica rice and allows it to adapt to a temperate climate. The results of this study extend our understanding of the northward expansion of rice cultivation and provide a target gene for the improvement of chilling tolerance in rice.
Zinc is an important micronutrient for both crop growth and human nutrition. In rice production, yields are often reduced and Zn mass concentrations in the grains are often low when Zn is in short supply to the crop. This may result in malnutrition of people dependent on a rice-based diet. Plant breeding to enhance low-Zn tolerance might result in higher yields and nutritional quality but requires effective selection criteria embedded in physiological insight into the Zn husbandry of the crop and applicable in field evaluation of advanced breeding material or in screening of existing varieties. Using existing and newly developed low-Zn tolerance indices, this study presents the results of screening experiments carried out in high-and low-Zn soils. Sixteen accessions of aerobic rice were grown under greenhouse conditions to conceptualize the indices and 14 under field conditions to validate the indices. As the differences in soil-Zn levels in these experiments did not result in differences in grain yield, literature data were used from experiments where the soil-Zn level did have an effect on grain yield, to further check the validity of the indices. Several indices were applied to evaluate the genotypic low-Zn tolerance performance in attaining (relatively) high grain yield, high grain-Zn mass concentration, or both. The results indicate that the grain-Zn mass concentration efficiency index is different from the grain yield efficiency index and that the low-Zn tolerance indices identified superior genotypes best. Amongst the indices tested, the low-Zn tolerance index for grain yield and the low-Zn tolerance index for grain-Zn mass concentration were closely correlated with grain yield and grain-Zn mass concentration, respectively. Therefore, the low-Zn tolerance index for grain yield was effective in screening for high stability and high potential of grain yield, and the low-Zn tolerance index for grain-Zn mass concentration was effective for grain-Zn mass concentration under low and high soil-Zn conditions.
This work studies the effect of lubricant inertia on the fluid cavitation for partially sealed high-speed squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs). The lubricant cavitation is modeled by both the Elrod algorithm and the Gumbel's cavitation boundary condition to provide the comparison between the most common lubricant cavitation models. Additionally, the fluid inertia is integrated by adapting a finite-length SFD model for partially sealed dampers. The integrated SFD model is incorporated into a numerical simulation model and the results are validated by comparison with experimental data. The results of the analysis demonstrate that the fluid inertia effects significantly extend the cavitation region and influence the cavitation onset and the film reformation.
GENE LIAO is currently Director of the Electric-drive Vehicle Engineering and Alternative Energy Technology programs and Professor at Wayne State University. He received a M.S. in mechanical engineering from Columbia University, and a doctor of engineering from University of Michigan, Ann Arbor. He has over 17 years of industrial practices in the automotive sector prior to becoming a faculty member. Dr. Liao has research and teaching interests in the areas of hybrid vehicles, energy storage, and advanced manufacturing.
Prof
Direct Ink Writing Extruders for Biomedical Applications AbstractThere are many 3D printing processes using various printing materials for different applications.Among these printing methods, robocasting or direct ink writing (DIW) is suitable and mostly adopted for biology and biomedical applications. DIW is an additive manufacturing technique in which a filament of 'ink' is extruded from a nozzle. The ink is usually supplied through a syringe or container and does not need to be heated to a high temperature to extrude through the nozzle for printing. Therefore, cells and bacteria can survive during the printing process. The ink must have high viscosity or be gel-like to maintain the sturdy structure for the printed object before post-processing. Several professional DIW printers designed for biomedical and medical research are available in the market such as EnvisionTEC 3D-Bioplotter, however they are usually extremely expensive. Collaborating with the medical school, this project will design and build new extruding systems on a low-cost RepRap machine. One RepRap Prusa i3 printer is modified able to extrude independently two different hydro-gels dedicated to the stem cell research. The modification is expected to utilize other 3D printing methods to create parts. This is a team's Capstone Design Project with students involved to promote and extend the applications of 3D printing. Student working processes of design, hardware modification, as well as testing procedures will be observed and recorded. The project activities, the testing results, and the students' learning experiences and outcomes will be present in this paper. Student working processes of design, hardware modification, as well as programing procedures are observed and evaluated for systematic course material development.
In this paper, the effect of a circumferential central groove on an open-ended squeeze film damper is analytically investigated. Flow equations in both the central groove and film land are solved by applying the technique of separation of variables. Model validation is presented by a rotor-squeeze film damper test rig using a recorded squeeze film damper film pressure, where a significant improvement from a classical squeeze film damper model is shown. It is found that the central groove has a high and stable pressure region while neglecting the groove effect that would over-estimate the damping force. Both simulation and experiment show that the increase of supply flow escalates the damper pressure and it could possibly avoid the film cavitation, thus raising the squeeze film damper reaction force. In addition, the effects of different groove cross-section shapes including rectangle, square, semi-circle, and semi-ellipse are evaluated. Model sensitivity shows that the size of the central groove has more impact on the damper performance than the shape of the groove.
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