TheT*-T relation for chrominum-potassium alum

TheT*-T relation for powdered chromium-potassium alum was determined by calibration with a CMN thermometer. The result was considerably different from the hitherto reported ones but was highly reproducible. The obtained relation is expressed in the region ofT=600–30 mK as a linear equationT=1.01T*+1.01(4/3–)fC–47.0 (mK), where is the demagnetizing factor,f the filling factor, andC the Curie constant. The effect of the crystalline field on this relation is discussed.     

GaAs-AlxGa1-xAs integrated twin-guide lasers with distributed Bragg reflectors

A GaAs-AlxGa1-xAs integrated twin-guide (ITG) laser with distributed Bragg reflectors (DBR) was fabricated. The DBR was in the form of a third-order grating which was chemically etched on the surface of the output waveguide. The ITG lasers with distributed Bragg reflectors (DBR-ITG lasers) operating at room temperature showed single mode oscillation up to 1.5 times the threshold current and the half-side external quantum efficiency was 1 ∼ 2 percent.     

An investigation of the fractionation of whey proteins by two microfiltration membranes with nominal pore size of 0.1 μm

There is growing interest in the fractionation of whey proteins because of the specific properties of individual whey proteins. The objective of this work was to assess the efficiency of two membranes to obtain two fractions, one rich in β‐lactoglobulin (β‐Lg) and the other rich in α‐lactalbumin (α‐La) from a whey‐protein concentrate using microfiltration (MF). Two MF membranes were tested for the fractionation: a flat‐sheet membrane VCWP and a spiral membrane MF‐7002, both with nominal pore sizes of 0.1 μm. The VCWP retained 78% of the proteins in solution, and this membrane was shown to be permeable to both proteins, β‐Lg and α‐La. The retention of protein by MF‐7002 was 65%, and there was a partial retention of lactose. The permeate collected in the MF‐7002 in the concentration stage was over 50%α‐La; although this was present in lower concentrations, it was passed preferentially to the permeate. The results indicated that some aggregation of the proteins may have occurred under the experimental conditions because there was only a partial separation of the proteins under study.     

A Y-fed directional coupler modulator with a highly linear transfer curve

We demonstrated a linearized Y-fed directional coupler modulator in Z-cut LiNbO/sub 3/. The proof-of-concept device employed two electrode sections of opposite polarity whose lengths were chosen based on the results of our previous theoretical modeling. A highly linear modulation characteristic and improved tolerance to fabrication errors were achieved with a simple design, in excellent agreement with the theory. The linearity exceeded 90% over a wavelength range of 45 nm, centered around 1530 nm, with a maximum linearity of 97% at 1510 nm and a maximum modulation depth of 98%. By comparison, the linearity of conventional modulators is typically around 70%. Thus the device was proven to have a high linearity with a wide usable spectral range and relaxed fabrication tolerances.     

Histopathologic and radiographic findings of the simple bone cyst

Biosynthesis of extracellular alkaline guanyl-specific RNase by Bacillus circulans (RNase Bci) was studied. Synthesis of the enzyme by the culture started in the late exponential phase and was inhibited by inorganic phosphate and glucose, in contrast to the biosynthesis of its structural and functional homologue, RNase Ba (barnase) of B. amyloliquefaciens. It is suggested that differences in the regulation of the biosynthesis of RNase Bci and Ba are related to different structures of their gene promoters.     

Semi-rational Engineering of a Promiscuous Fatty Acid Hydratase for Alteration of Regioselectivity

Fatty acid hydratases (FAHs) catalyze regio- and stereo-selective hydration of unsaturated fatty acids to produce hydroxy fatty acids. Fatty acid hydratase-1 (FA-HY1) from Lactobacillus Acidophilus is the most promiscuous and regiodiverse FAH identified so far. Here, we engineered binding site residues of FA-HY1 (S393, S395, S218 and P380) by semi-rational protein engineering to alter regioselectivity. Although it was not possible to obtain a completely new type of regioselectivity with our mutant libraries, a significant shift of regioselectivity was observed towards cis-5, cis-8, cis-11, cis-14, cis-17-eicosapentaenoic acid (EPA). We identified mutants (S393/S395 mutants) with excellent regioselectivity, generating a single hydroxy fatty acid product from EPA (15-OH product), which is advantageous from application perspective. This result is impressive given that wild-type FA-HY1 produces a mixture of 12-OH and 15-OH products at 63 : 37 ratio (12-OH : 15-OH). Moreover, our results indicate that native FA-HY1 is at its limit in terms of promiscuity and regiospecificity, thus it may not be possible to diversify its product portfolio with active site engineering. This behavior of FA-HY1 is unlike its orthologue, fatty acid hydratase-2 (FA-HY2; 58 % sequence identity to FA-HY1), which has been shown earlier to exhibit significant promiscuity and regioselectivity changes by a few active site mutations. Our reverse engineering from FA-HY1 to FA-HY2 further demonstrates this conclusion.