No abstract

Ammonium influx into plant roots via the high-affinity transport system (HATS) is down-modulated under elevated external ammonium, preventing ammonium toxicity. In ammonium-fed Arabidopsis, ammonium transporter 1 (AMT1) trimers responsible for HATS activity are allosterically inactivated in a dose-dependent manner via phosphorylation of the conserved threonine at the carboxyl-tail by the calcineurin B-like protein 1-calcineurin B-like protein-interacting protein kinase 23 complex and other yet unidentified protein kinases. Using transcriptome and reverse genetics in ammonium-preferring rice, we revealed the role of the serine/threonine/tyrosine protein kinase gene OsACTPK1 in down-modulation of HATS under sufficient ammonium. In wild-type roots, ACTPK1 mRNA and protein accumulated dose-dependently under sufficient ammonium. To determine the function of ACTPK1, two independent mutants lacking ACTPK1 were produced by retrotransposon Tos17 insertion. Compared with segregants lacking insertions, the two mutants showed decreased root growth and increased shoot growth under 1 mm ammonium due to enhanced ammonium acquisition, via aberrantly high HATS activity, and use. Furthermore, introduction of OsACTPK1 cDNA fused to the synthetic green fluorescence protein under its own promoter complemented growth and the HATS influx, and suggested plasma membrane localization. Root cellular expression of OsACTPK1 also overlapped with that of ammonium-induced OsAMT1;1 and OsAMT1;2. Meanwhile, threonine-phosphorylated AMT1 levels were substantially decreased in roots of ACTPK1-deficient mutants grown under sufficient ammonium. Bimolecular fluorescence complementation assay further confirmed interaction between ACTPK1 and AMT1;2 at the cell plasma membrane. Overall, these findings suggest that ACTPK1 directly phosphorylates and inactivates AMT1;2 in rice seedling roots under sufficient ammonium.

The interdiffusion of the compositional atoms was investigated at heterointerface between a GaAs epilayer and a Ge(111) substrate by secondary ion mass spectroscopy. When a thin AlAs layer is applied initially, diffusion of Ge into the GaAs epilayer was suppressed effectively. An abrupt heterointerface was successfully realized in relatively high temperature growth. The interdiffusion process at the AlAs-Ge heterointerface was clarified in high temperature growth, which was dominated by the temperature-assisted segregation of Ge atoms during the AlAs growth rather than thermal diffusion. The compositional diffusion of Al atoms into the GaAs epilayer was also observed, which was enhanced by the Ge segregation in the structure of GaAs/AlAs/Ge substrate grown at higher temperature.

Interaction between 96% alumina and three binary glassesfor this study. A penetration model of alumina by glass is used as frits in thick-film technology is studied. A possible proposed based on scanning electron microscopy (SEM) and interfacial reaction mechanism where a melt glass peneelectron probe microanalysis (EPMA) studies of the interfacial trates into the alumina through the grain boundaries dismicrostructure between alumina and glass. The degree of penesolving SiO 2 , one of the grain boundary components, is tration is discussed in terms of the viscosity and the surface suggested. The formulation expressing the glass penetration tension of the melt glass. rate into the alumina based on Poiseuille's law, assuming the driving force for the glass penetration is the capillary II. Experimental Procedure force, is consistent with the experimental growth rate of the reaction layer in the alumina. The formulation also clearly explains the relationship of the degree of glass penetration(1) Alumina to the viscosity and the surface tension of the melt glass. TheWell-sintered dense 96% alumina (Kyocera) was used for the extraordinary difference in K, designated as the coefficient alumina sample because it is commonly used for thick-film of penetration, between the calculated result and the expericeramic substrates. Table I shows the properties of the alumina. mental result suggests that the process of dissolving SiO 2As shown in Fig. 1, the alumina contains SiO 2 , MgO, and a into a melt glass at the alumina grain boundaries retards small amount of CaO as the minor components. the glass penetration.( 2) Glass Preparation 7,8Three binary glass systems with various ratios (mol%) of I. Introduction glass modifier to glass former were selected for the glass G LASS is an important constituent in thick-film materials that samples: 10PbOи90B 2 O 3 to 90PbOи10B 2 O 3 , 40PbOи60SiO 2 performs different functions according to the nature of the to 90PbOи10SiO 2 , and 10Bi 2 O 3 и90B 2 O 3 to 90Bi 2 O 3 и10B 2 O 3 . thick-film layer. In thick-film conductors, glass is added to These glasses are commonly used as bonding agents in thickpromote adhesion with the ceramic substrate and sintering of film materials. In the PbO-SiO 2 system, glasses with SiO 2 the conductive metal powders. In thick-film dielectrics, glass greater than 60 mol% were not used because of their high improves densification, dielectric strength, and adhesion, and it melting temperatures. provides passivation. In thick-film resistors, glass is vital as a Calculated amounts of reagent-grade chemicals (PbO, Bi 2 O 3 , matrix for the cermet structure, and it determines the electrical SiO 2 , and H 3 BO 3 ) for the various glass compositions were properties, such as resistivity, and the temperature coefficient.weighed, mixed, and melted in a platinum crucible in an Each application places its own unique set of demands on the air atmosphere at 1000ЊC for 3 h. The molten glasses were glass phase used. Therefore, the glass transition temperature, quenched on a plati...

We have performed molecular-dynamics (MD) simulations of hydrogenated amorphous silicon (a-Si:H) thin-film growth using realistic many-body semiclassical potentials developed to describe Si-H interactions. In our MD model, it was assumed that SiH3, SiH2 and the H radicals are main precursors for the thin-film growth. In MD simulations of a-Si:H thin-film growth by many significant precursor SiH3 radicals, we have evaluated average radical migration distances, defect ratios, hydrogen contents, and film growth rates as a function of different incident radical energies to know the effect of the radical energization on the properties. As a result of the comparison between the numerical and experimental results, it was observed that the agreement is fairly good, and that an increase of radical migration distance due to the radical energization is effective on a- Si:H thin-film growth with a low defect.