Survey of histamine content in seafood on the market

Food poisoning involving histamine has occurred almost every year for 20 years in Tokyo, and is usually due to ingestion of fish with lean meat, such as sardine, mackerel, horse mackerel and so on. Therefore, we were investigated the levels of histamine and 4 non-volatile amines (tyramine, putrescine, cadaverine, spermidine) in 637 samples on the market. The water activity of samples in which histamine was detected at 5 mg/100 g and over was examined. Histamine, tyramine, putrescine, cadaverine and spermidine were detected in 66, 43, 26, 64 and 5 samples, and the detection ranges were 5-340, 5-51, 5-42, 5-180 and 5-8 mg/100 g, respectively. Most of the samples in which histamine was detected were semi-dried round and split sardine. Water activity of 24 samples of semi-dried round and split sardine in which histamine was detected was in the range of 0.68-0.96.     

Combination effect of phospholipids and n-3 polyunsaturated fatty acids on rat cholesterol metabolism

This study evaluated phospholipids (PLs) containing n-3 polyunsaturated fatty acids (n-3 PUFAs) for their specific inherent effects and effects due to a combination of the presence of glycerophosphate structure and n-3 PUFAs on cholesterol metabolism in rats. Rats were fed a diet of AIN-93G containing soybean oil (SO, 7%), SO (5.8%)+fish oil (1.2%), SO (5.2%)+soybean PLs (1.8%), SO (5.2%)+PLs containing n-3 PUFAs (1.8%), and SO (4.0%)+fish oil (1.2%)+soybean PLs (1.8%). Diets with PLs containing n-3 PUFAs, and soybean PLs in combination with fish oil, resulted in decreased serum and liver cholesterol levels through enhancement of fecal cholesterol excretion and suppression of liver sterol regulatory element binding protein-2 mRNA expression compared with the diet containing soybean oil alone. This study shows that soybean PLs with added triacylglycerol that included n-3 PUFAs have the same effects on cholesterol metabolism as PLs containing n-3 PUFAs, and that these could be of benefit to people.     

Single-Component Pheromone Consisting of Bombykal in a Diurnal Hawk Moth, <Emphasis Type="Italic">Neogurelca himachala sangaica</Emphasis>

Recent work has suggested that hawk moths share pheromone components but are sexually separated by qualitative and quantitative differences in their pheromone blends. During field assays on the sex pheromones of other species, a diurnal hawk moth, Neogurelca himachala sangaica (Lepidoptera: Sphingidae), was frequently captured, but the composition of the sex pheromone of this species was not known. Analysis of hexane extracts of the pheromone glands of calling female by gas chromatography (GC) using an electroantennographic detector (EAD) revealed two components that elicited EAD responses from male moth antennae. These components were identified by their mass spectra and retention indices on two GC columns as (10E,12Z)-10,12-hexadecadienal (E10,Z12–16:Ald) and a trace of its (10E,12E)-isomer (E10,E12–16:Ald) in 98:2 ratio. In field experiments, E10,Z12–16:Ald alone attracted male moths, and addition of E10,E12–16:Ald significantly reduced the attractiveness, even at the naturally-occurring ratio. Analysis of the data using a generalized linear mixed model showed that E10,Z12–16:Ald positively contributed to attractiveness, whereas E10,E12–16:Ald did so negatively, and it was concluded that the sex pheromone of N. himachala sangaica consists solely of E10,Z12–16:Ald, bombykal. The negative effect of E10,E12–16:Ald on attractiveness could promote the species-specificity of this single-component pheromone system.     

Dynamical Transition of 4He Crystallization in a Very High Porosity Aerogel

Crystallization of ⁴He in aerogels of 90 and 96% porosities shows a dynamical phase transition at around 600 mK due to the competition between thermal fluctuation and disorder: crystals grow via creep at high temperatures and via avalanche at low temperatures. In a very high porosity 99.5% aerogel, however, the transition had not been observed in our previous publication (Nomura et al. in Phys. Rev. Lett. 101:175703, 2008). We improved the spatial resolution of the video image and found that the 99.5% aerogel did have the transition at around 200 mK, which is much lower than those of the lower porosities. The avalanche size is significantly smaller in the 99.5% aerogel. The reduction in the transition temperature and avalanche size may be the consequence of weaker disorder for the crystallization in the very high porosity aerogel.     

Moderately high speed impact of two identical spheres

This paper deals with impacts between two identical spheres in moderately high speed range. Impact of spheres is one of basic problems in mechanical dynamics. Severity of impact is generally characterized by the coefficient of restitution. However, influence of material property on the coefficient of restitution has not been clarified yet. The authors previously investigated direct central impacts of two identical spheres in low speed range and revealed that strain rate sensitivity of material properties could not be ignored even in the low speed impacts. Therefore, this paper investigates the direct central impact of two identical spheres in higher speed range. The impact experiments were performed in range of impact speed 10 m/s–20 m/s by using air-gun setup. It was confirmed that the expressions for the coefficient of restitution and the contact time derived from the low speed impact remained effective in the moderately high speed range. Then numerical simulations by using Finite Element Method (F.E.M) have been carried out, in which the material properties and the strain rate effect were taken into account. The coefficient of restitution, contact time, sphere’s compression and contact circle diameter obtained by experiments and F.E.M. were compared and they matched well. Contact pressure distributions at maximum contact force were investigated. The contact pressure at sphere center varied little with impact speed but the contact pressure increased with impact speed near contact edge. Theoretical expression for prediction of the coefficient of restitution proposed by C. Thornton was examined to the experimental results of this study. To provide an accurate prediction, it is necessary to estimate the contact pressure depending on material properties. Finally, the Meyer analysis was applied to the case of this study and it was found that the Meyer’s law holds in the moderately high speed impact between two identical spheres.     

Solid dispersion particles of tolbutamide prepared with fine silica particles by the spray-drying method

Solid dispersion particles of tolbutamide (TBM) were prepared by formulating nonporous (Aerosil 200 (hydrophilic), Aerosil R972 (hydrophobic)) or porous (Sylysia 350 (hydrophilic), Sylophobic 200 (hydrophobic)) silica as a carrier and applying the spray-drying (SD) or evaporation (Eva) method. In the solid dispersion particles prepared by the SD method, TBM existed in a meta-stable form (Form II) irrespective of the type of silica. On the other hand, when the Eva method was used, various crystalline forms of TBM were observed in the solid dispersion particles according to the type of silica. Polymorphs of Forms III and IV were prepared with Aerosil 200 and Aerosil R972, respectively, while crystalline Form II was obtained when either of the forms of porous silica, Sylysia 350 or Sylophobic 200, was formulated. The dissolution property of TBM in the solid dispersion particles prepared with hydrophilic silica was remarkably improved compared with those of the original TBM crystals (Form I) or spray-dried TBM without silica (Form II). In the case of hydrophobic silica, the release rate of TBM from the solid dispersion particles was much slower than that of original TBM. The meta-stable form of TBM in the solid dispersion particles was stable for at least 4 weeks when stored at 60 °C and 0% RH, while the spray-dried TBM without silica (Form II) was gradually converted to the stable form (Form I) under the same storage conditions. Under the humid storage conditions (60 °C, 75% RH), the spray-dried TBM without silica (Form II) immediately converted into the stable form (Form I) within 1 day, while TBM (Form II) in the solid dispersions in a matrix of silica was stable for at least 1 week.