Zhao Zhang

© 2016, American Society for Biochemistry and Molecular Biology Inc. All rights reserved.Glycyl-tRNA synthetase is the enzyme that covalently links glycine to cognate tRNA for translation. It is of great research interest because of its nonconserved quaternary structures, unique species-specific aminoacylation properties, and noncanonical functions in neurological diseases, but none of these is fully understood. We report two crystal structures of human GlyRS variants, in the free form and in complex with tRNAGly respectively, and reveal new aspects of the glycylation mechanism. We discover that insertion 3 differs considerably in conformation in catalysis and that it acts like a "switch" and fully opens to allow tRNA to bind in a cross-subunit fashion. The flexibility of the protein is supported by molecular dynamics simulation, as well as enzymatic activity assays. The biophysical and biochemical studies suggest that human GlyRS may utilize its flexibility for both the traditional function and alternative functions.

Tree branches near the electric power transmission lines are of great threat to the electricity supply. Nowadays, the tasks of clearing threatening tree branches are still mostly operated by hand and simple tools. Traditional structures of the multirotor aerial robot have the problem of fixed structure and limited performance, which affects the stability and efficiency of pruning operation. In this article, in order to obtain better environmental adaptability, an active deformable trees-pruning aerial robot is presented. The deformation of the aerial robot is implemented through two ways, arm telescopic and folding. In order to suppress the influence of internal and external disturbances on the system, Active Disturbance Rejection Control technology is adopted to build the flight controller. Firstly, active deformation aerial robot structure is given, followed by system dynamic model establishment under wind disturbance using the Newton–Euler method. Also, the analysis of the gusts influence on the system is considered. Then, the active deformation aerial robot system is decoupled into a combination of six SISO systems, so that a disturbance rejection controller is designed. Finally, the expanded state observer and the nonlinear state error feedback law are used to inspect and compensate the disturbance. Simulation results of attitude and position tracking as well as the antidisturbance capability show that the active deformation aerial robot with the ADRC flight controller designed in this paper has excellent attitude control capabilities during flight and trees-pruning operation.

The Cabin Pressure Control System is an essential part of the aviation environmental control system that ensures aircraft structure and flight crew safety. However, the CPCS usually has potential faults of sensors and actuators. To this end, a Simple Adaptive Control- based reconfiguration method is proposed to compensate for the above adverse effects. Some good pressure control performance of CPCS can be achieved by the basic pressure controller when the system is in normal operation. A parallel feedforward compensator is designed to guarantee the closed-loop system’s stability and the almost strictly positive realness of the augmented system. Thus, the simple adaptive controller can be utilized for the CPCS. In particular, the reconfiguration system can update the control law online when the fault occurs without the system identification process. The reference model is obtained by mathematical model linearization after considering the mechanical characteristics of the CPCS. Extensive simulations under various typical fault scenarios are carried out throughout the entire flight envelope of the aircraft from take-off to landing. Simulation results validate the robustness and reconfiguration control capability of the proposed method.

© 2015 American Chemical Society.Near-infrared dye-sensitized upconversion nanoparticles can broaden the absorption range and boost upconversion efficiency of UCNPs. Here, we achieved significantly enhanced upconversion luminescence in dye-sensitized core/active shell UCNPs via the doping of ytterbium ions in the UCNP shell, which bridged the energy transfer from the dye to the UCNP core. As a result, we synergized the two most practical upconversion booster effectors to amplify upconversion efficiency. We demonstrated two biomedical applications using these UCNPs. By using dye-sensitized core/active shell UCNP embedded poly polymer implantable systems, we successfully shifted the optogenetic neuron excitation window to a biocompatible and deep tissue penetrable 800 nm wavelength. Furthermore, UCNPs were water-solubilized with Pluronic F127 with high upconversion efficiency and can be imaged in a mouse model.

© 2014 Elsevier B.V.. Nitrogen pollution is a global environmental problem that has greatly increased the risks of both the eutrophication of surface waters and contamination of ground waters. The majority of N pollution mainly comes from agricultural fields, in particular during rice growing seasons. In recent years, a gradual shift from the transplanting rice cultivation method to the direct seeding method has occurred, which results in different water and N losses from paddy fields and leads to distinct impacts on water environments. The N transport and transformations in an experimental direct-seeded-rice field in the Taihu Lake Basin of east China were observed during two consecutive seasons, and simulated using Hydrus-1D model. The observed crop N uptake, ammonia volatilization, N concentrations in soil, and N leaching were used to calibrate and validate the model parameters. The two most important inputs of N, i.e., fertilization and mineralization, were considered in the simulations with 220 and 145.5kgha-1 in 2008 and 220 and 147.8kgha-1 in 2009, respectively. Ammonia volatilization and nitrate denitrification were the two dominant pathways of N loss, accounting for about 16.0% and 38.8% of the total N input, respectively. Both nitrification and denitrification processes mainly occurred in the root zone. N leaching at 60 and 120cm depths accounted for about 6.8% and 2.7% of TNI, respectively. The crop N uptake was 32.1% and 30.8% of TNI during the 2008 and 2009 seasons, respectively, and ammonium was the predominant form. Simulated N concentrations and fluxes in soil matched well with the corresponding observed data. Hydrus-1D could simulate the N transport and transformations in the DSR field, and could thus be a good tool for designing optimal fertilizer management practices in the future.

In the recent decade, increasing costs of labor, water, and fertilizers around the world led to a change in the method of crop establishment from traditional transplanted rice to direct-seeded rice and to a substantial rise in the DSR-managed area. Since water management in areas with DSR is quite different from those with TPR, vertical water movement and water and nutrient losses during the crop season may be different as well. Water flow and water losses in a DSR field in the Taihu Lake Basin of east China were monitored and evaluated using Hydrus-1D during two seasons with different rainfalls and irrigation managements. While during the 2008 season, irrigation accounted for 57% of the total water input, during the 2009 season, it accounted for only 32%. Due to large rainfall during the wet, 2009 rice season, surface runoff accounted for about 17.0% of TWI. During the much drier 2008 rice season with higher irrigation inputs, surface runoff could be controlled much better. Modeled evapotranspiration during the 2008 and 2009 seasons accounted for 54.6% and 44.6% of TWIs, respectively. Measured and simulated results indicate that water leaching was the main path of water loss from the DSR fields, which implies that frequent irrigation increases water leaching. The plough sole layer played a major buffering role for water flow during both dry and wet seasons. Water productivities evaluated from TWIs during the 2008 and 2009 seasons were 0.71 and 0.59kg/m3, respectively; they were 1.30 and 1.33kg/m3 when evaluated from modeled evapotranspiration fluxes. Pressure heads and vertical fluxes simulated using Hydrus-1D matched measured data well. The Hydrus-1D can be used to simulate water flow and water balance in the DSR fields. © 2014 Elsevier B.V.

This paper shows how analytic modeling research in the Marketing field is focused on answering questions of "How?" and "Why?" It describes the disciplines involved in analytic modeling; examines how the key criteria of parsimony and robustness help to define a good model; and discusses other goodness criteria, including appropriate use of analytic techniques, applicability of the model to institutionally rich, real-world problems, non-obvious results, generalizability, and ability to provide insight where other research techniques do not work. The paper defines and discusses key concepts in analytic models of distribution channels, including double marginalization, coordination, incentive alignment and contract design, strategic substitutability and complementarity, externalities, and principal-agent problems. Next, the paper summarizes research presented in the session on analytic models in channels at the Erin Anderson conference; and finally, the paper suggests avenues for future analytic modeling research.