GaInP/AlGaInP double-heterostructure laser grown on a(111)B-oriented GaAs substrate by metalorganic chemical vapourdeposition

Room temperature continuous-wave operation of a Ga_0.5In _0.5P/(Al_0.5Ga_0.5)_0.5In _0.5P double-heterostructure laser grown on a (111)B-oriented GaAs substrate by metalorganic chemical vapour deposition was obtained for the first time. The threshold current was 99 mA. The emission wavelength was around 650 nm, which was about 30 nm shorter than that of a similar laser grown on a (100)-oriented GaAs substrate     

Roles of cuticular hydrocarbons in intra-and interspecific recognition behavior of two rhinotermitidae species

Soldiers of two termite species.Reticulitermes speratus andCoptotermes formosanus, showed aggressive behavior toward workers of other species. Soldiers always exhibited aggressive behavior to a conspecific worker treated with heterospecific cuticular hydrocarbons. A bioassay using live workers to test contact chemical cues was developed.     

Lipid composition of 30 species of yeast

The detailed composition of cellular lipid of more than 23 species of yeast has been determined quantitatively by thinchrography on quartz rods, a method previously used for estimating cellular lipids of seven species of yeast. That data was fortified by neutral and phospholipid quantitations on 30 species of yeast cells. Most of the test organisms contained 7–15% total lipid and 3–6% total phospholipid per dry cell weight, except for the extremely high accumulation of triglycerides in two species ofLipomyces. Qualitatively, 30 species of yeast cells contained similar neutral lipid constituents (triglyceride, sterol ester, free fatty acid, and free sterol) and polar lipid components (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, cardiolipin, and ceramide monohexoside) without minor constituents. Based on the quantitative composition of neutral lipids, the 30 species of yeast were divided into two groups, the triglyceride predominant group and the sterol derivative group. These groupings were fairly well overlapped from the standpoint of the distribution characteristics of fatty acid. The relative polar lipid compositions also grossly resembled each other. Only one exception of polar lipid composition in yeast cells was found inRhodotorula rubra species which contained phosphatidyl ethanolamine as the most abundant phospholipid. Fatty acid distribution patterns in yeast cells consistently coincided with other reports concerning fatty acid composition of yeast cells. Correlation of lipid composition and classification of yeasts are suggested and discussed. A part of this investigation has been reported at the 14th conference of the Japan Oil Chemists' Society, Nagoya, Japan, October 1975.     

Digital DPCM Codec for TV Signals Based onDeltaM/DPCMDigital Conversions

A digital differential pulse-code modulation (DPCM) codec based on ΔM/DPCM and DPCM/ΔM digital conversions is presented as an equivalent replacement of a conventional DPCM codec for TV signals by using digital processing technology. A generalized model and equivalent circuit are shown for the digital DPCM codec, and transfer characteristics and quantizing noises are analyzed. The digital DPCM codec is designed for 1-MHz TV signals and the performance is verified by experiments. By the use of double integration ΔM and digital filter technology, it is shown that at the ΔM sampling rate of 16 MHz the overall SNR performance is sufficiently good for use as a conventional DPCM codec, and the digital code converters can be realized with commercially available transistor-transistor-logic (TTL) medium-scale-integrated (MSI) circuits and low-power emitter-coupled-logic (ECL) integrated circuits (IC's).     

Brightness uniformity in liquid crystal television display

A liquid crystal matrix display has been developed for television. It has a larger panel size and a larger number of dots than liquid crystal displays for calculators and watches. However, it has been difficult to display intermediate grey areas with uniform brightness. The conditions necessary to obtain uniform brightness are discussed.     

Dendrite coarsening during solidification of hypo- and hyper-eutectic Al-Cu alloys

Dendrite coarsening during cooling at a constant rate was compared at various stages of solidification with that during isothermal holding for Al-Cu alloys of hypo- and hypereutectic compositions. For each specimen, the undercooling for the initial dendrite formation and the time elapsed after it were measured directly. The dendrite arm spacing was shown to be determined solely by the latter, and the dendrite structure was therefore coarsening-controlled from the early stage of solidification. The rate of coarsening in terms of the dendrite arm spacing during solidification at a constant cooling rate was same as that during isothermal holding in all the alloys tested. Numerical values of the fractional rate of solidification were evaluated for the hypo-eutectic compositions and the results show that the rate of dendrite coarsening does not depend on the fractional rate of solidification. Aluminium dendrites show structural coarsening with progressive solidification in the same way as during isothermal holding. CuAl₂ dendrites show curved boundaries after isothermal holding whereas those cooled at a constant rate are faceted.