Evaluation of a pneumatic-shielded spraying system by CFD simulation

Shielding spray booms is one strategy recommended for reducing spray drift. Although many studies related to mechanical shields show positive effect on reducing spray drift, little information about the use of pneumatic shields is available. In this study, several pneumatic shield designs were rated based on drift potential by means of the FLUENT computational fluid dynamics (CFD) software package. For relative comparisons, conventional spraying using nozzles, air-assisted spraying, and air-shear spraying were included in the analysis. Results of this study indicate that not all simulated cases of pneumatic-shielded spraying provided better drift control. To ensure reduced drift potential and to reduce power required for pneumatic-shielded spraying, optimal operating parameters for the dominant variables appeared to be a jet velocity of 40 m s-1, a jet flow rate of 1.7 m3 s-1 m-1 of boom length, and a jet angle of 15° forward. Optimal operating parameters, obtained from analysis of variance, were similar to results from previous studies on air-assisted and air-shear spraying. Pneumatic-shielded spraying, with proper choice of operating parameters, may be a suitable alternative to reduce spray drift

Mutation of a nitrate transporter, AtNRT1 : 4, results in a reduced petiole nitrate content and altered leaf development

Unlike nitrate uptake of plant roots, less is known at the molecular level about how nitrate is distributed in various plant tissues. In the present study, characterization of the nitrate transporter, AtNRT1:4, revealed a special role of petiole in nitrate homeostasis. Electrophysiological studies using Xenopus oocytes showed that AtNRT1:4 was a low-affinity nitrate transporter. Whole-mount in situ hybridization and RT-PCR demonstrated that AtNRT1:4 was expressed in the leaf petiole. In the wild type, the leaf petiole had low nitrate reductase activity, but a high nitrate content, indicating that it is the storage site for nitrate, whereas, in the atnrt1:4 mutant, the petiole nitrate content was reduced to 50-64% of the wild-type level. Moreover, atnrt1:4 mutant leaves were wider than wild-type leaves. This study revealed a critical role of AtNRT1:4 in regulating leaf nitrate homeostasis, and the deficiency of AtNRT1: 4 can alter leaf development

TUUSAT-1A: The First Academic Microsatellite Developed by Universities in Taiwan

This paper describes the mission and current design results of Taiwan Universities-United SATellite NO.1A (TUUSAT-1A), which is a student microsatellite developed by a conjunct program of several universities in Taiwan. The mission goal of TUUSA-1A, according to the priority, includes two CMOS cameras of 1.3 million pixels for Earth imaging, one GPS receiver for orbital determination, and the commercial off-the-shelf (COTS) components for space qualification. The TUUSAT-1A main body is cube-shaped with size of 25 x 25 x 25 cm3 and weight of 26.4 kg. It is expected to be launched into a circular orbit with 500 km altitude and 21 degrees inclination by piggyback from most launch vehicles. Currently, the TUUSAT-1A project is on the design phase and the Critical Design Review (PDR) will be accomplished in October 2007. TUUSAT-1A is expected to be launched in the middle of 2008. This paper describes the mission and current design results of TUUSAT-1A, the results of environmental tests status of the COTS components by using NSPO Integration and Test Facility, and lessons learned from the program