Detection of Leuconostoc strains at a meat processing plant using polymerase chain reaction

To simplify the labor-intensive conventional routine testing of samples to detect Leuconostoc at a meat processing plant, we developed polymerase chain reaction (PCR) primers specific for Leuconostoc from 16S rRNA gene sequences. These primers did not detect other common lactic acid bacteria such as Lactobacillus plantarum, Lact. sake, Lact. fermentum, Lact. acidophilus and Weissella viridescens. PCR with this primer detected all Leuconostoc species tested (Leu. mesenteroides subsp. mesenteroides, Leu. pseudomesenteroides, Leu. carnosum, Leu. lactic, Leu. citreum, Leu. amelibiosum, Leu. gelidum), except for Leu. fallax, and no other lactic acid bacteria on agarose gel electrophoresis. The method could identify areas contaminated with Leuconostoc in a large-scale industrial meat processing plant. Of 69 samples analyzed, 34 were positive for Leuconostoc according to the conventional culture method (isolation of LAB producing dextran) and PCR, whereas 29 were negative according to both. Six samples were culture-negative but positive by PCR. No false negative results were generated by PCR. The method is rapid and simple, is useful for routinely monitoring areas contaminated with Leuconostoc in meat processing plants, and could help to prevent the spoilage of meat products.     

A development of an equilibrium analysis model between electricity retailers under competitive environment

This paper provides a novel equilibrium model for analyzing behaviors of the electric retailers under competitive environment. In the deregulated electricity retail market, the retailers purchase the electricity power and sell it to consumers at the competitive prices. According to their risk attitudes, the retailers optimize the selling prices and the purchase allocation between a day‐ahead market and forward contracts. Without the regulation, an equilibrium by those selfish decision‐making processes of multiple retailers would cause an adverse impact on the electricity market and also the power system. From stable and economical viewpoints, it is important to analyze the unfavorable equilibrium. The selfish behaviors of retailers are modeled as an equilibrium problem with equilibrium constraints in this paper and formulated as a mixed integer linear programming problem to obtain a generalized Nash equilibrium by commercial solvers efficiently. Through computational examples, the proposed model and formulation are validated.     

High magnesium concentration inhibits ligand-stimulated calcium influx and hormone secretion in rat pituitary lactotropes with involvement of intracellular free magnesium

The effects of extracellular magnesium concentration ([Mg2+]ex) on thyrotropin-releasing hormone (TRH)-stimulated intracellular free calcium mobilization and prolactin secretion were investigated concomitantly with measurement of the intracellular free magnesium concentration ([Mg2+]i). TRH-stimulated intracellular free calcium mobilization was significantly inhibited when the medium was replaced by high Mg2+ medium ([Mg2+]ex = 10 mM) in normal Ca2+ medium. The inhibitory effects of high Mg2+ became apparent concomitantly with an increase in [Mg2+]i from 0.7 to 1.3 mM. High Mg2+ significantly inhibited TRH-induced PRL secretion in a dose-dependent manner in normal Ca2+ medium. TRH-stimulated inositol triphosphate (IP3) production was rather augmented by the replacement with high Mg2+ medium. In summary, high Mg2+ inhibits Ca2+ influx stimulated by TRH in the rat pituitary lactotropes, possibly with the involvement of [Mg2+]i increase. These results have general importance in relation to high Mg(2+)-induced suppression of the biological functions of cells.     

Infiltration of fibrous preform by molten aluminum in a centrifugal force field

The pressure to infiltrate molten aluminum into alumina short-fiber preforms was generated by centrifugal force, and it was proved that centrifugal force is effective as a motive force for the infiltration and sound composites that are produced. The initiation pressure of the infiltration was also calculated and obtained clearly. The start pressure agreed well with the threshold pressure obtained theoretically. The characteristics of the infiltration in the preform was discussed using a one-dimensional solution of D’Arcy’s law in a centrifugal force field. It was made clear that when preform surface pressure is low, the region having lower pressure than the threshold pressure appears in the infiltrated region.     

Early detection of recurrent hepatocellular carcinoma

BACKGROUND/AIMS: Early detection and treatment of recurrent hepatocellular carcinoma (HCC) are keys to patient survival after hepatic resection. In attempts at early detection, we make use of the alpha-fetoprotein (AFP) test every month and abdominal ultrasound (US) and computed tomography (CT) are carried out every three months after hepatectomy. The objective of the present study was to evaluate the most appropriate interval for follow-up re-examinations after resection for HCC. PATIENTS AND METHODS: Eighty-five patients with recurrent HCC were divided into two groups according to the state of the tumor when recurrence was detected: Group I (n = 70); tumor size < or = 2.0 cm, and group II (n = 15); tumor size > or = 2.1 cm. Clinicopathological comparisons were made between the two groups. RESULTS: AFP positivity in group I was significantly lower than group II at the time of recurrence. Rates of extrahepatic intra-abdominal recurrences, i.e. recurrence at the surgical stump and in the abdominal cavity and lymph nodes around the liver, were more frequent in group II than in group I (47% vs 4%; p < 0.001). The average tumor size was larger in 10 patients with extrahepatic intra-abdominal recurrence than in 75 patients with intrahepatic recurrence (3.4 +/- 2.0 vs 1.6 +/- 0.6 cm; p < 0.0001). There was a statistically significant difference regarding the histological grade of initial HCC between the two patterns of recurrence. CONCLUSIONS: Measurements of AFP were seen to have limited value for detecting recurrence, at an early stage. Close postoperative follow-up, including bedside US in the outpatient clinic, should be carried out when the initial HCC is histologically less differentiated HCC.     

Cationic ring-opening polymerization of 2-substituted-2-oxazolines initiated by carbon black surface

Summary Carbon blacks were found capable of initiating the ringopening polymerization of 2-substituted-2-oxazolines at relativery high temperatures. The activation energy of the polymerization of 2-methyl-2-oxazoline was estimated to be 13.4 kcal/mol. Carbon black lost the initiating activity of the polymerization upon the blocking of carboxyl groups on the surface by the treatment with potassium hydroxide or diazomethane. Therefore, it was concluded that carboxyl groups on carbon black play an important role in the initiation of the polymerization. Furthermore, it was found that during the polymerization, poly(N-acylethyleneimine) was grafted onto carbon black by the termination of growing polymer chain with the surface.     

X-ray Diffraction Study of the Structure of Silicon Nitride Fiber Made from Perhydropolysilazane

Continuous stoichiometric silicon nitride fiber was produced by the pyrolysis of perhydropolysilazane. This high-purity silicon nitride fiber is colorless and has high strength, modulus of elasticity, and thermal stability which are properties suitable for reinforcing plastics, metals, glasses, and even ceramics. The structures of three kinds of amorphous silicon nitride fibers (with stoichiometric, Si-excess and O-excess composition) were investigated by X-ray diffraction followed by calculating the radial distribution functions. Radial distribution functions were calculated from several possible crystal structures and compared with observed radial distribution functions.     

Comparative study of various methods for thermogravimetric analysis of polystyrene degradation

Various methods of thermogravimetric analysis were compared in case of polystyrene degradation. The reaction order, the activation energy and the preexponential factor were evaluated from common TG curves experimentally obtained. In most cases a 5-mg sample of polystyrene with 110,000 molecular weight was decomposed at heating rate of 10°C/min. The reaction was found under this experimental condition to be of first order with activation energy of 61.0 kcal/mole, though there were slight differences depending on the analytical methods used.