Production of tyramine in "moromi" mash during soy sauce fermentation

The concentrations of 7 non-volatile amines, tyramine (Tym), histamine (Him), phenethylamine (Phm), putrescine (Put), cadaverine (Cad), spermidine (Spd) and spermine (Spm) in the liquid part of "moromi" mash during soy sauce fermentation were studied. These amines, except for him and Cad, were detected during fermentation by the conventional production method in the laboratory. Put and Spd were detected at the beginning, and Tym, Phm and Spm appeared later; these 5 amines increased gradually during the fermentation. Put, Spd, Spm and Cad were present in the raw starting material for soy sauce; thus, Tym and Phm were produced by the fermentation. When "moromi" mash was added to liquid medium and cultivated, Tym was detected in some "moromi" mash and the other amines were not detected. Tym-producing bacterial strains were isolated from the liquid culture media of Tym-positive "moromi" mash. The Tym-producing strain was a gram-positive coccus. The conditions for production of amines by Tym-producing bacterial strains were examined. These strains grew and produced tyramine under various conditions, which may occur during soy sauce fermentation. Namely, Tym was produced at pH 5-10, at salt concentrations of less than 8%, under either aerobic or anaerobic conditions. During soy sauce fermentation, it is assumed that Tym would be produced by these strains during the early stages of soy sauce aging within a short period when the salt concentration and pH conditions are optimal for growth. Based on the bacteriological properties, the strains were identified as Enterococcus faecium. With the exception of Phm and Him, which did not exist in the starting raw material, non-volatile amines (including Put, Cad, Spd and Spm) were not produced and microorganisms producing them are not believed to be present during "moromi" fermentation.     

Ultrahigh-speed pseudomorphic InGaAs/InAlAs HEMTs with 400-GHzcutoff frequency

An excellent cutoff frequency (f_t) as high as 400 GHz was successfully realized in 45-nm-gate pseudomorphic InGaAs/InAlAs high electron mobility transistors (HEMTs). An additional vertical gate-recess suppressed short-channel effects, while keeping good pinchoff characteristics. Gate length (L_g) dependence of electron transit time (τ_transit) implied an increased saturation velocity (υ_s) of 3.6×10⁷ cm/s in the developed pseudomorphic HEMTs. This f_t is the highest value ever reported for any transistors to date     

Transmission electron microscopic observation of a metastable phase on the thermal decomposition process of Ca-deficient hydroxyapatite

Calcium-deficient hydroxyapatite (Ca-def HAp) decomposes to stoichiometric hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) at high temperature. In a previous study, we reported that a metastable phase with a high Ca/P molar ratio appeared in the temperature range from 700 to 800°C. In the present study, the formation process of a metastable phase and the crystallographic relationship between the Ca-rich metastable phase and HAp matrix were investigated by high-resolution transmission electron microscopy (HRTEM). Ca-def HAp was annealed at 600–850°C for 2 or 6 h in air. TEM observations were performed before and after annealing Ca-def HAp. Based on analysis of image of Ca-def HAp before annealing, several HAp crystals with different aspect ratios agglomerated. The metastable phases grew thicker by long-term annealing. HRTEM image suggested that the Ca-rich metastable phase was formed by migration to the interface and continuous accumulation of calcium ions from HAp crystals with a small aspect ratio. From HRTEM images and results of the analysis of selected area electron diffraction patterns along the [010], [110] and [001] zone axes, lattice constants of the metastable phases were determined to be a = 2.86 nm, b = 0.94 nm, and c = 0.69 nm with orthorhombic crystals system.     

On fracture analysis using an element overlay technique

In this paper, an element overlay technique (s-FEM [Comput. Struct. 43 (1992) 539]) is applied to various two dimensional linear fracture problems. When s-FEM is adopted, local finite element model concerning cracks can be built independently from the global finite element mesh for modeling overall structure. The local model is superposed on the global one. Therefore, it is tractable to introduce cracks in an existing finite element model. The accuracy of s-FEM is critically examined and it is found that the size of local mesh region needs to be larger than or roughly equal to that of an element in the global mesh.     

High transconductance of 2.25 S/mm observed at 16 K for 195-nm-gate In/sub 0.75/Ga/sub 0.25/As/In/sub 0.52/Al/sub 0.48/As HEMT fabricated on [411]A-oriented InP substrate

We achieved a maximum transconductance (g/sub m/) of 2.25 S/mm at 16 K for a 195-nm-gate In/sub 0.75/Ga/sub 0.25/As/In/sub 0.52/Al/sub 0.48/As pseudomorphic high-electron mobility transistor (PHEMT) fabricated on a [411]A-oriented InP substrate, which is the highest value ever reported for HEMTs. This PHEMT also showed a much enhanced cutoff frequency (f/sub T/) of 310 GHz at 16 K, compared with its room temperature value (245 GHz). The significantly enhanced g/sub m/ and f/sub T/ at 16 K can be attributed to the higher saturation velocity in the region "under the gate," which is caused not only by suppressing the phonon scattering, but also by suppressing the interface roughness scattering due to the "(411)A super-flat InGaAs/InAlAs interfaces" (effectively atomically flat heterointerfaces over a wafer-size area).     

Surface small crack growth behavior in low-cycle fatigue at elevated temperature and application limit of macroscopic crack growth law

Surface small crack growth behavior of Type 304 stainless steel in low cycle fatigue under fast-fast and slow-fast cyclings was investigated at a temperature of 873 K, by means of the smooth specimens with various grain sizes. It was shown that once the small cracks had grown up to a few grains size, they predominantly propagated with strain cycling, while most of small cracks stopped propagating when they grew up to one grain size. It was also shown that the small crack growth rate significantly slowed down where the crack length was integral multiple of the grain size. Above behavior resulted from the grain boundaries temporarily impeding the small crack growth. The crack length below which the grain boundaries affected the small crack growth rate was also given as function of the relative length to the grain size. Furthermore, the small crack growth rate was compared with the macroscopic crack growth one. In fast-fast cycling, the small crack growth rate was about ten times as large as as the macroscopic crack growth one where its length was comparable to the grain size. Based on the results thus obtained, the application limit of macroscopic crack growth law to the surface small crack growth was discussed. The macroscopic crack growth law was not applicable to the small crack growth, until the crack length was about ten times average grain size in fast-fast and slow-fast cyclings.     

Effects of smoking and nicotine on the gastric mucosa: a review of clinical and experimental evidence

Epidemiological and experimental evidence have shown that nicotine has harmful effects on the gastric mucosa. The mechanisms by which cigarette smoking or nicotine adversely affect the gastric mucosa have not been fully elucidated. In this report, clinical and experimental data are reviewed. The effects of nicotine from smoking on gastric aggressive or defensive factors are discussed. Nicotine potentiates gastric aggressive factors and attenuates defensive factors; it also increases acid and pepsin secretions, gastric motility, duodenogastric reflux of bile salts, the risk of Helicobacter pylori infection, levels of free radicals, and platelet-activating factor, endothelin generation, and vasopressin secretion. Additionally, nicotine impairs the therapeutic effect of H2-receptor antagonists and decreases prostaglandin synthesis, gastric mucosal blood flow, mucus secretion, and epidermal growth factor secretion. Although many of the studies provide conflicting results, the bulk of the evidence supports the hypothesis that nicotine is harmful to the gastric mucosa.