Gel filtration of surfactants

A simulation technique was developed for analyzing the gel filtration chromatography of surfactants. Theoretical elution curves obtained by this technique were compared with the experimental curves for the following five systems: an ionic or a nonionic surfactant of a single component, an ionic surfactant in the presence of an electrolyte, a mixture of two nonionic surfactants, a mixture of two ionic surfactants, and a mixture of an ionic and a nonionic surfactant. In the first four systems, good agreement was found between the theoretical and experimental elution curves. A possible explanation for the disagreement in the last system is presented.     

InGaAs avalanche photodiode with InP p-n junction

A new InGaAs avalanche photodiode structure that has an InGaAs light absorption region and InP avalanche multiplying region is proposed. A dark-current density of 2.2 × 10?3 A/cm2 at 90% of breakdown voltage and a multiplication factor of 45 were obtained for the new structure diode fabricated from a liquid-phase epitaxially grown wafer.     

Separation of sulfated bile acids by high-performance liquid chromatography

In order to establish a new method for simultaneous determination of sulfated bile acids without deconjugation, separation of 3-sulfates of unconjugated, glyco- and tauroconjugated bile acids by high-performance liquid chromatography has been undertaken. The preliminary experiment indicated that reversed phase chromatography on an ODS SC-02 column using ammonium carbonate aqueous solution/acetonitrile as a mobile phase would be promising. The ratio of peak width to retention time was varied depending upon the salt concentration. The content of water in mobile phase exerted an influence on the capacity ratio to a certain extent, but not on the resolution. The use of 0.5% ammonium carbonate/acetonitrile (26∶8 and 20∶8, v/v) was found to be suitable for complete resolution of sulfated cholate, chenodeoxycholate, deoxycholate, lithocholate and their glyco- and tauro-conjugates.     

Irradiation effects of boron carbide used as control rod elements in fast breeder reactors

The paper describes radiation effects on 8₄C pellets used as control rod elements in the Enrico Fermi Fast Breeder Reactor. Pellet swelling (Δ$\text{V/V}$) caused by irradiation was less than 1% in which crystal lattice swelling was less than 20%. Many microcracks, a main cause of pellet swelling, appeared in the irradiated pellets. The production of microcracks was related to graphite precipitation in the pellets before irradiation. Open pores which did not exist in the unirradiated pellets were formed in the irradiated ones. In a unit cell of B₄C, the α-axis elongated by 0.025 Å and the $\text{c-}\text{axis}$ shrank by 0.07 Å by irradiation. Moreover, we found three recovery stages which were from room temperature to 400°C, from 400 to 750°C and from 850 to 1100°C. The recovery mechanisms in the irradiated pellets are discussed in terms of the helium behavior.     

Endoscopic electromyographic study on upper gastrointestinal tract (author's transl)

Recently we made the electromyographic study on human gastrointestinal tract using the endoscopic method is useful for the clinical studies of the patho-physiological aspects on human gastrointestinal tract. The silver bipolar needle electrode which was 0.2 mm in diameter, 10 mm in length and 1.0 mm in interpolar distance and the electroencephalography recorder provided with pen-writer were used for this research. The endoscopy was done to the volunteer anesthetized his pharynx with xylocaine spray. 20 cases of gastro-electromyograms, 35 cases of duodeno-electromyograms and 5 cases of the electromyograms of duodenal papilla were recorded. On these endoscopic electromygorams, the typical rhythms and patterns of electrical activities were disturbed by various kinds of factors; that is, on the endoscopic manipulation, the sticking of needle electrode into the shallow layer of gastrointestinal wall and automatical pouring of water into canal through the endoscope. On volunteers' condition, his deep breathing, electrocardiogram and vasotonic condition were important factors. Typical duodeno-electromyograms showed the grouped spikes synchronizing with the duodenal peristalsis observed endoscopically. The electromyograms of the duodenal papilla showed the similar patterns and rhythms to those of duodeno-electromyograms on active phase. In the clinical study on the correlation and propagation between gastric and duodenal motility, the rhythms of electrical activities on duodeno-electromyograms were not similar to the rhythms of gastric peristalsis at the prepyloric region. The propagation of gastric movement to duodenal bulb were not able to be clarified. We assumed that the gastric and duodenal motility occurred each other on the different rhythms.     

Stress-sensitive properties of silicon-gate MOS devices

Stress-sensitive properties were measured on both p- and n-channel silicongate MOS devices fabricated on (100) Si at room temperature. Stress-induced variations in drain currents for both enhancement- and depletion-mode MOS transistors with various channel-dopings were measured over a wide range of gate biases. In addition to piezoresistance effect, remarkable drain-current variations were observed at weak-inversion and explained theoretically in terms of changes in minority carrier densities due to energy band shifts by stresses. Elastoresistance shear-constants for polycrystalline-silicon gate layers were also obtained and compared with coefficients for source-drain diffused layers. Further, the elastoresistance of p-type polycrystalline-silicon films was investigated on doping-concentration dependences. A theoretical model for polycrystalline-silicon elastoresistance was developed based on the barrier model for conductivity in polycrystalline-silicon. Results obtained from the model were compared with the experimental results and found to be in good agreement at higher doping-concentrations than trap density.     

Structural analysis of an N-glycan with "beta1-4 bisecting branch" from human serum IgG by negative-ion MSn spectral matching and exoglycosidase digestion

A novel N-linked oligosaccharide (N-glycan) with "beta1-4 bisecting branch (galactose beta1-4 bisecting N-acetylglucosamine)" was found in human serum IgG. Its structure was efficiently analyzed by using beta-galactosidase digestion, a MSn spectral library database, and negative-ion MS2 spectral matching. For confirmation, the novel N-glycan was synthesized by using an expected standard N-glycan (acceptor), UDP-galactose (donor), and beta1-4 galactosyltransferase. This work also demonstrates that the MSn spectral library database, in particular, negative-ion MS2 spectral matching, can efficiently reduce the number of specific, sequential exoglycosidase digestions required and is useful for rapid structural analysis of unknown glycans not in the database.     

Simultaneous analysis of 2-aminopyridine-derivatized neutral and sialylated oligosaccharides from human serum in the negative-ion mode by sonic spray ionization ion trap mass spectrometry

Neutral and acidic (sialylated) 2-aminopyridine-derivatized (PA) oligosaccharides were analyzed by using reversed-phase high-performance liquid chromatography/ion trap mass spectrometry (RP-HPLC/IT MS) with a sonic spray ionization (SSI) source. Under the RP-HPLC separation using a buffer of 1 mM ammonium acetate (pH4.3) at a flow rate of 0.2 mL/min, both PA-oligosaccharides in the negative-ion mode showed a comparable degree of ionization efficiency, differing from that of the positive-ion mode, which exhibits a wide gap between their ionization efficiencies. In addition, the ion intensities of both PA-oligosaccharides were higher in the negative-ion mode than in the positive-ion mode. These results strongly suggest that the negative-ion mode of SSI-MS is suitable for simultaneous analysis of neutral and acidic (sialylated) oligosaccharides in RP-HPLC/MS. In the present study, RP-HPLC/SSI-IT MS in the negative-ion mode was used in the analysis of PA-oligosaccharides from human serum and its usefulness was investigated. As a result, 32 neutral and sialylated PA-oligosaccharides from human serum were identified with differentiating isomeric oligosaccharides and relatively quantified by a single HPLC/MS run. This method is useful for simple and rapid analysis of the overall distribution of neutral and sialylated oligosaccharides in a complex sample such as serum.