Fine-sized BaMgAl10O17:Eu phosphor powders prepared by spray pyrolysis from the spray solution with BaF2 flux

Fine-sized BaMgAl₁₀O₁₇:Eu²⁺ phosphor powders with plate-like morphology were prepared by spray pyrolysis process. The effects of ratio of BaF₂ and Ba(NO₃)₂ used as the source materials of Ba component on the morphological and optical properties of the BaMgAl₁₀O₁₇:Eu²⁺ phosphor powders were investigated. BaF₂ was used as the flux material as well as the source material of Ba component. The phosphor powders prepared from the spray solution with the same mole concentrations of BaF₂ and Ba(NO₃)₂ had fine size, plate-like morphology and narrow size distribution. The addition of BaF₂ as the source material of Ba component increased the photoluminescence intensities of the phosphor powders. The phosphor powders prepared from the spray solution with the ratios of BaF₂ and Ba(NO₃)₂ larger than 1 had the similar photoluminescence intensities to that of the commercial product.     

Sideband noise of a large phase carrier in interferometric sensors

Interferometric sensors using balanced detectors and phase stabilisation schemes remain susceptible to laser intensity noise if phase carrier techniques are employed. An intensity stability of 4 × 10?6 is required for the low-frequency side-band noise to be equivalent to microradian phase shift sensitivity if the phase carrier has a peak phase shift of ?/2 rad.     

Shrink‐Wrapped Boundary Face Algorithm for Mesh Reconstruction from Unorganized Points

A new mesh reconstruction scheme for approximating a surface from a set of unorganized 3D points is proposed. The proposed method, called a shrink‐wrapped boundary face (SWBF) algorithm, produces the final surface by iteratively shrinking the initial mesh generated from the definition of the boundary faces. SWBF surmounts the genus‐0 spherical topology restriction of previous shrink‐wrapping‐based mesh generation techniques and can be applied to any type of surface topology. Furthermore, SWBF is significantly faster than a related algorithm of Jeong and others, as SWBF requires only a local nearest‐point‐search in the shrinking process. Our experiments show that SWBF is very robust and efficient for surface reconstruction from an unorganized point cloud.     

Mutagenesis of the conserved residue Glu259 of Gsalpha demonstrates the importance of interactions between switches 2 and 3 for activation

We previously reported that substitution of Arg258 within the switch 3 region of Gsalpha impaired activation and increased basal GDP release due to loss of an interaction between the helical and GTPase domains (Warner, D. R., Weng, G., Yu, S., Matalon, R., and Weinstein, L. S. (1998) J Biol. Chem. 273, 23976-23983). The adjacent residue (Glu259) is strictly conserved in G protein alpha-subunits and is predicted to be important in activation. To determine the importance of Glu259, this residue was mutated to Ala (Gsalpha-E259A), Gln (Gsalpha-E259Q), Asp (Gsalpha-E259D), or Val (Gsalpha-E259V), and the properties of in vitro translation products were examined. The Gsalpha-E259V was studied because this mutation was identified in a patient with Albright hereditary osteodystrophy. S49 cyc reconstitution assays demonstrated that Gsalpha-E259D stimulated adenylyl cyclase normally in the presence of GTPgammaS but was less efficient with isoproterenol or AlF4-. The other mutants had more severely impaired effector activation, particularly in response to AlF4-. In trypsin protection assays, GTPgammaS was a more effective activator than AlF4- for all mutants, with Gsalpha-E259D being the least severely impaired. For Gsalpha-E259D, the AlF4--induced activation defect was more pronounced at low Mg2+ concentrations. Gsalpha-E259D and Gsalpha-E259A purified from Escherichia coli had normal rates of GDP release (as assessed by the rate GTPgammaS binding). However, for both mutants, the ability of AlF4- to decrease the rate of GTPgammaS binding was impaired, suggesting that they bound AlF4- more poorly. GTPgammaS bound to purified Gsalpha-E259D irreversibly in the presence of 1 mM free Mg2+, but dissociated readily at micromolar concentrations. Sucrose density gradient analysis of in vitro translates demonstrated that all mutants except Gsalpha-E259V bind to beta gamma at 0 degreesC and were stable at higher temperatures. In the active conformation Glu259 interacts with conserved residues in the switch 2 region that are important in maintaining both the active state and AlF4- in the guanine nucleotide binding pocket. Although both Gsalpha Arg258 and Glu259 are critical for activation, the mechanisms by which these residues affect Gsalpha protein activation are distinct.     

Promising zeolite-type hydrocarbon trap catalyst by a knowledge-based combinatorial approach

Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst.     

Effect of impact energy on the impact-wear properties of low carbon high manganese alloy steels in corrosive conditions

The impact-wear properties of low carbon high manganese alloy steel were tested under three different impact energies (0.7 J, 1.2 J and 1.7 J) using a modified MLD-10 wear tester. SEM inspection of the wear surface and subsurface optical metallographic analysis reveal the impact wear mechanism. Under corrosive conditions we observe a shift from single micro-cutting to impact-flaking, after the appearance of vertical section micro-cracks, while at higher impact energies fatigue corrosion and abrasion are observed.