Nano-scaled Pt/Ag/Ni/Au contacts on p-type GaN for low contact resistance and high reflectivity

We synthesized the vertical-structured LED (VLED) using nano-scaled Pt between p-type GaN and Ag-based reflector. The metallization scheme on p-type GaN for high reflectance and low was the nano-scaled Pt/Ag/Ni/Au. Nano-scaled Pt (5 A) on Ag/Ni/Au exhibited reasonably high reflectance of 86.2% at the wavelength of 460 nm due to high transmittance of light through nano-scaled Pt (5 A) onto Ag layer. Ohmic behavior of contact metal, Pt/Ag/Ni/Au, to p-type GaN was achieved using surface treatments of p-type GaN prior to the deposition of contact metals and the specific contact resistance was observed with decreasing Pt thickness of 5 A, resulting in 1.5 x 10(-4) ohms cm2. Forward voltages of Pt (5 A)/Ag/Ni contact to p-type GaN showed 4.19 V with the current injection of 350 mA. Output voltages with various thickness of Pt showed the highest value at the smallest thickness of Pt due to its high transmittance of light onto Ag, leading to high reflectance. Our results propose that nano-scaled Pt/Ag/Ni could act as a promising contact metal to p-type GaN for improving the performance of VLEDs.

Performance of GaN vertical light emitting diodes using wafer bonding process with Al-alloyed graphite substrate

We report on the vertical-structure light emitting diodes (VLEDs) fabricated with wafer bonding method using Al-alloyed graphite and Si supporter. VLEDs with Al-alloyed graphite produced no crack during/after laser lift-off (LLO) techniques while the wafer crack took place using Si supporter because of the difference of thermal expansion coefficients between Si and sapphire. The performance of VLEDs with wafer bonding method using Al-alloyed graphite supporter was compared to those fabricated by Cu plating methods. The output power of the chips with wafer bonding method was nearly same as the one with Cu-plating method. However, the forward voltage of VLEDs with wafer bonding method was higher than those with Cu-plating method. In the terms of reliabilities the wafer bonding process is more preferable to Cu-plating and our report proposes that Al-alloyed graphite could be one of promising candidates for the supporters in wafer bonding process.

Conditional sigma factor expression, using the inducible acetamidase promoter, reveals that the Mycobacterium tuberculosis sigF gene modulates expression of the 16-kilodalton alpha-crystallin homologue

A chemically inducible acetamidase promoter-sigF fusion gene was integrated into the chromosome of Mycobacterium bovis BCG. Two-dimensional protein gel analysis permitted the identification of a number of protein spots whose expression was SigF related. One spot upregulated by inappropriate induction of sigF expression corresponded to the 16-kDa antigen alpha-crystallin.

IgE-mediated triggering signals for mediator release from human mast cells and basophils

Human basophils were developed in suspension culture of mononuclear cells of cord blood in the presence of conditioned medium of phytohemagglutinin-stimulated human T cells, from which interleukin 2 had been eliminated. Approximately 50-90% of cells recovered after 2-4 wk of culture were basophil granulocytes, which bear receptors with high affinity for human IgE. Sensitization of the cells with human IgE followed by challenge with anti-IgE resulted in the release of histamine and arachidonic acid (AA). In both the cultured basophils and human lung mast cells, bridging of cell-bound IgE with anti-IgE induced a transient increase in phospholipid methylation and intracellular cyclic AMP (cAMP), and these processes were followed by Ca2+ uptake and release of both histamine and AA. As demonstrated in rat mast cells, evidence was obtained that the activation of a proteolytic enzyme and phospholipid methylation induced by the bridging of IgE receptors are involved in the subsequent increase in AMP, and are an essential step for transduction of triggering signals for mediator release.

IgD levels in white and Metis communities in Saskatchewan

Levels of serum IgD have been measured in white and Metis (Cree Indian) communities in Saskatchewan. IgD levels in the Metis were, on average, 10 times as high as those in the white population. In both groups IgD levels rose rapidly to reach, by the age of two years, levels which did not differ significantly from those found in the adult. From the age of two to three years, levels in the populations remained relatively constant with time, although levels in any of individual may rise or fall over a three-year period by factors ranging from 10 to 20.

Immunoglobulin levels in smokers and non-smokers

Immunoglobulin levels were compared in smoking and non-smoking grain handlers and teachers. Mean IgC and IgM levels were significantly lower, and IgE levels were significantly higher, in the smokers than in the non-smokers. IgA levels were also lower but with the numbers studied not significantly so. IgD levels were unchanged.

Immunoglobulin levels in white and metis communities in Saskatchewan

Serum-immunoglobulin levels (IgG, IgM, IgA, IgD, IgE) have been studied in white and metis (Cree Indian) communities in Saskatchewan. The levels of IgG, IgA, IgD and IgE were higher in the metis than in the whites. Both IgG and IgM were higher in females than in males. IgG and IgA levels rose progressively with age. IgM levels rose rapidly during the first year to almost adult levels, and then fell gradually after the age of 30. IgE levels also rose rapidly during the first 3 years of life, were higher on average in children than in adults, and fell to adult levels at puberty. Low levels of IgA were associated with high levels of IgG; they were not associated with either high levels of IgE or an increase in the prevalence of asthma.