Enhancement of surface acidity and catalytic activity by glass formation of calcium metaphosphate

Effective acid sites for the dehydration of 2-propanol and isomerization of 1-butene were found to be generated by glass formation of calcium metaphosphate. The number of these sites with strong acidity remarkably decreased by the crystallization of the glass, where the condensation of hydroxyl groups were significant. Thus, the sites must be the monohydrogen phosphate protons.     

An advanced defect-monitoring test structure for electrical screening and defect localization

A new test structure for the detection and localization of short and open defects in large-scale integrated intralayer wiring processes is proposed. In the structure, an open-monitoring element in the first metal layer meanders around lines of short-monitoring elements placed in contact with N-type diffusion regions to make the structure compact. The proposed structure allows defective test structures to be screened through electrical measurements and killer defects to be localized through voltage contrast or optical microscopy methods.     

Influence of charged droplet cloud on flashover of air gaps for lightning impulse voltage

Transmission lines passing through a mountainous region often are struck by winter lightning. As a result, numerous double-circuit faults occur. Space charge might be responsible for this phenomena. Several investigations on flashover characteristics have been performed focusing on reduction of flashover voltage due to ionic space charge formed by corona discharge. In this paper, flashover characteristics of an air gap within a charged droplet cloud ejected from an airless nozzle using an induction charging method are discussed. The droplets are charged in the range -200 to 200 μC/kg, forming the space-charge density of approximately 13 μC/m³. The flashover voltage and the time lag to flashover were measured when 1.2 × 50 μs lightning impulse voltage applied to a rod-sphere gap is placed within the charged cloud. Flashover voltage for a positive rod increased markedly within a positive charged cloud by increasing the charge-to-mass ratio. The increase of flashover voltage was up to 80 percent in comparison with uncharged droplets. Flashover voltage for the negative rod decreased about 20 percent in the cloud of either polarity. The results show that the presence of charged droplets in the air gaps affects the discharge process significantly.     

Increased expression of endothelial cell nitric oxide synthase (ecNOS) in afferent and glomerular endothelial cells is involved in glomerular hyperfiltration of diabetic nephropathy

Root coverage procedures have become an important part of periodontal therapy. The purpose of this study was to compare 2 techniques, 1) guided tissue regeneration (GTR) with a bioabsorbable polylactic acid softened with citric acid ester membrane and 2) the connective tissue graft combined with a coronally positioned pedicle graft without vertical incisions. The GTR procedure produced a mean root coverage of 92.3% and the connective tissue graft combined with a coronally positioned pedicle graft, 95.0%. This difference was not statistically significant. Both procedures produced similar reductions in recession depth, recession width, and probing depth. The connective tissue graft combined with a coronally positioned pedicle graft resulted in a greater increase in the amount of keratinized tissue. Based on this study, both procedures can result in statistically similar amounts of mean root coverage, but the results are not identical. In most cases, the connective tissue with coronally positioned pedicle graft produced a more bulky result than guided tissue regeneration. Therefore, the procedures are not interchangeable.     

Sequence analysis of functional regions of homoserine dehydrogenase genes from L-lysine and L-threonine-producing mutants of Brevibacterium lactofermentum

The homoserine dehydrogenase (HD) genes from Brevibacterium lactofermentum lysine- and threonine-producing mutants were cloned, using the polymerase chain reaction, and sequenced. We found the amino acid substitutions, Val104Ile in the lysine-producing mutants in which HD may cause leaky mutation and Ser393Phe in the threonine-producing mutant with feedback-insensitive HD.     

Development of an automatic Vickers hardness testing system usingimage processing technology

The mechanical characteristics of machines or machine parts depend on the properties of the materials from which they are made. Hardness is an especially important index for machine design. The Vickers hardness number of a test material is defined by the surface area of the indentation made in the surface of a test specimen by a diamond pyramid indenter. Diagonal lines that indicate the indentation size are usually several micrometers to several hundred micrometers long, depending on the hardness of the material. Conventional automatic Vickers hardness testing systems have been applied only to specular-polished specimens. A new fully automatic Vickers hardness testing system has been developed that emulates visual Vickers hardness testing in terms of accuracy and that automatically sets the threshold level of the image processor to suit indentation image data. It can be applied not only to the testing of rough-polished specimens while meeting the measurement accuracy specified in Japanese Industrial Standard (JIS) B 7725, but can also process one indentation within 20 s, including the indenting, focusing and image processing time     

Group velocity dependence of propagation losses in single-line-defect photonic crystal waveguides on GaAs membranes

Group velocity, v/sub g/, dependence of propagation loss in single-line-defect photonic crystal waveguides on GaAs membranes, and minimum loss as low as 2.5 dB/mm, are presented. When v/sub g/ is reduced by a factor of 7, an additional loss is found to be only 5 dB/mm, thus proving a feasible usage of low v/sub g/.