Inhibition of the growth of cariogenic bacteria in vitro by plant flavanones

Phytoalexins, defensive compounds produced by plants against microbial infections, were purified from Sophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2',4'-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 micrograms/ml.     

Mouse beta-galactoside alpha 2,3-sialyltransferases: comparison of in vitro substrate specificities and tissue specific expression

Four types of beta-galactoside alpha 2,3-sialyltransferase (ST3Gal I-IV) have been cloned from several animals, but some contradictory observations regarding their substrate specificities and expression have been reported. Therefore, it is necessary to concurrently analyze the substrate specificities of the four enzymes, of which the source should be one animal. Accordingly, the acceptor substrate specificities and gene expression of mST3Gal I-IV were analyzed. Since we had already cloned ST3Gal I and II, as previously reported (Lee, Y.-C. et al., Eur. J. Biochem., 216, 377-385 (1993); J. Biol. Chem., 269, 10028-10033 (1994)), the cDNAs of ST3Gal III and IV were cloned from mouse cDNA libraries. Each of the four enzymes was expressed in COS-7 cells as a recombinant enzyme fused with protein A, and applied on an IgG-Sepharose gel to eliminate endogenous sialyltransferase activity. ST3Gal I and II showed the highest activity toward Gal beta 1, 3 GalNAc (type III), very low activity toward Gal beta 1,3GlcNAc (type I), but none toward Gal beta 1,4GlcNAc (type II). ST3Gal III and IV exhibited high activity toward the type I and II disaccharides, but very low activity toward the type III one. On the other hand, asialo-GM1 (Gg4Cer) was as good a substrate for ST3Gal I and II as the type III disaccharide, though ST3Gal III and IV hardly utilized glycolipids as substrates, as indicated by in vitro experiments. Northern blot analysis revealed that enzymes of the ST3Gal-family are expressed mainly in a tissue-specific manner. The ST3Gal I gene was strongly expressed in spleen and salivary gland, and weakly in brain, liver, heart, kidney, and thymus. The ST3Gal II gene was strongly expressed in brain, and weakly in colon, thymus, salivary gland, and testis, and developmentally expressed in liver, heart, kidney, and spleen. The ST3Gal III and IV genes were expressed in a wide variety of tissues. These differences in tissue specific expression suggest the expression of each ST3Gal influences the distribution of sialyl-glycoconjugates in vivo.     

Factors determining the damage coefficients and the low-frequency noise in MeV proton-irradiated silicon diodes

In this paper, the factors determining the reverse current and the recombination lifetime damage coefficients in high-energy proton-irradiated Si junction diodes are studied. These factors are: the particle energy, the crystal growth technique and corresponding starting material quality, and the substrate doping density and type. The observed macroscopic device degradation is discussed in view of the microscopic damage factor, the nonionizing energy loss (NIEL). Finally, the impact of proton irradiation on the low-frequency noise in forward operation is reported. Several experimental factors lead to the conclusion that the change in the flicker noise is related to the created ionization damage in the lateral oxide isolation at the periphery of the diode rather than to the bulk displacement damage.     

云雾爆炸场的工程计算

根据爆轰波和冲击波理论对国内外资料和野外试验结果做了分析，并且把云雾爆炸场划分成云雾区、云雾区界面和冲击波区。相应的爆炸超压和比冲量按有关的公式计算，其结果与实验测定值较接近。     

Gated-diode study of corner and peripheral leakage current in high-energy neutron irradiated silicon p-n junctions

It will be shown that an analysis of gated-diode (GD) structures enables to investigate the radiation damage in different parts of p-n junctions in a CMOS technology. This is important as the peripheral, especially corner, p-n junction leakage at reverse voltage sets the leakage and power consumption of state-of-the-art integrated circuits (ICs) and the DRAM retention time. One GD enables to extract the radiation-induced peripheral leakage-current defined by the isolation surrounding the active p-n junction, while two GDs with different dimensions-the corner leakage. The method is applied to junctions fabricated in different silicon substrate types and irradiated by 1-MeV equivalent neutrons with fluence (/spl Phi/) ranging from 5/spl times/10/sup 11/ to 5/spl times/10/sup 13/ n/cm/sup 2/. While for low to moderate /spl Phi/ the significance of the peripheral leakage-current decreases, a rebound occurs for the higher /spl Phi/ investigated due to the increase of the bulk peripheral leakage and of the corner component.     

8-channel×2.5 Gbit/s hybrid integrated multiwavelengthphotoreceiver module with arrayed-waveguide grating demultiplexer

A compact 8-channel hybrid integrated multiwavelength photoreceiver module has been fabricated. The module, which consists of an arrayed-waveguide grating demultiplexer with a 100 GHz spacing, a photodiode array using a planar lightwave circuit platform, and preamplifier integrated circuits, successfully operated at 2.5 Gbit/s with good receiver sensitivity better than -17.5 dBm at a bit error rate of 10^-9 for all channels     

A new treatment for penile conservation in penile carcinoma: a preliminary study of combined laser hyperthermia, radiation and chemotherapy

We have previously shown that the four promoters of the IGF2 gene are under a tight but dynamic control during human liver development, whereby P3 and P1 are reciprocally active before and after birth respectively while the P2 and P4 promoters are constitutively active at a relatively lower level. In this study, we investigated the methylation status of the promoters P1 and P3 of IGF2 and the promoter region of the H19 gene in developing human livers ranging from fetal to late adult. A region of about 300 bp immediately upstream of the IGF2 exon 5 was found to be subjected to a developmental-specific methylation and this may correlate to the P3 promoter activity. The P1 domain of IGF2 was also found to be methylated in a developmentally-specific pattern. The promoter region of the H19 gene displayed different methylation patterns in different development stages showing decreased general methylation with increase of age. Therefore, regional- and developmental-specific DNA methylation is displayed in the promoter regions of the IGF2 and H19 genes. This may be an important factor involved in gene regulation in the developing human liver.     

Interfacial layer in homoepitaxial InP grown by organometallic vapor phase epitaxy with TMIn and TBP

The effects of interfacial layers with high impurity concentration on the properties of homoepitaxial InP layers have been studied by far-infrared (FIR) magnetoabsorption, in addition to dc mobility, Hall effect, and photoluminescence (PL) measurements. The layers are grown by organometallic vapor phase epitaxy with trimethylindium and tertiarybutylphosphine. Impurity absorption as well as cyclotron resonance is observed in the FIR measurements. Variations in the intensity of the resonance signals and the mobilities obtained from the linewidths of the cyclotron resonance are interpreted by a double layer model, i.e. a bulk layer with an interfacial layer. Carrier concentrations, dc mobilities, and PL intensities of both bound excitons and free excitons are also explained by the model.     

Far infrared and millimeter wave studies of impurity scattering within electron-hole liquid in semiconductors

Despite the experimental evidence in far-infrared that impurities are ionized within the electron-hole liquid in silicon and germanium, combination of luminescence data with millimeter wave cyclotron resonance and far-infrared magneto-optics tells us that the impurity-assisted intervalley electron scattering within EHL in silicon can apparently be interpreted on the basis of neutral impurity scattering. Justification of simulating the impurity center within EHL as “neutral” is grounded for the electron scattering problem, making use of the atomic scattering theory in contrast with a simple ionized impurity model calculation with proper screening.