Characterization on the Conformation of Glucoamylase from Rhizopus niveus and Rhizopus delemar

Using the pH-jump (neutral to above 11) for Tyr-OH ionization as a probe, two glucoamylases from Rhizopus niveus and Rhizopus delemar were found to be caused the change in conformation, which is in a kinetically single step. The pH titration at pHs below 12 was carried out on a multidimensional correlation spectrophotometer. Correlations among the spectrophotometric properties: fluorescence, absorption and circular dichroism are almost identical for the two enzymes. These results suggest that conformational characteristics of the niveus enzyme is almost the same as that of the delemar one.     

SOURCES OF RESILIENCE IN THE COMPUTER AND SOFTWARE INDUSTRIES IN FRANCE

French hardware manufacturers were by and large incapable not only of translating technological advances into industrial products but even of understanding the new opportunities these advances offered. While true up to a point, this approach, focused on the failure of the so-called 'national champion' policy, is incapable of explaining why French providers of IT services have had considerable success both in their own domestic market and in the wider European market. The argument advanced is that a very active higher education policy and national research strategy has produced a supply of particularly valuable competences which feed the IT sector. In addition, the previous mission-oriented policies encouraged the development of effective technological districts which now nurture the appearance of a plethora of small, innovative IT firms.     

Effect of “soft-electron” (low-energy electron) treatment on three stored-product insect pests

Developmental stages of three stored-product insect pests viz. Tribolium castaneum (Herbst), Plodia interpunctella (Hübner) and Callosobruchus chinensis (L.) were exposed to “soft electrons”, low-energy electrons. Soft electrons at an acceleration voltage of 170 kV effectively inactivated eggs, larvae and pupae of T. castaneum and P. interpunctella. The adults of T. castaneum and P. interpunctella were inactivated by treatment for 10 min (4.8 kGy) and 15 min (7.2 kGy), respectively. Soft electrons at 170 kV also inactivated the eggs of C. chinensis effectively. The adults of C. chinensis survived a 15 min exposure (7.2 kGy), but were inactivated having lost the ability to walk after a 5 min exposure (2.4 kGy). Soft electrons at 170 kV could not completely inactivate the larvae of C. chinensis inside beans, because the electrons with low penetration did not reach the larvae due to the shield of beans. The movement of T. castaneum larvae exposed to soft electrons was sluggish for several days, and then the larvae died with their hindguts emerged from their posterior ends 17 days after the treatment. DNA comet assay of cells of P. interpunctella larvae indicated that soft electrons at 170 kV damaged DNA in the larvae.     

Irradiation inactivation of Listeria monocytogenes in low-fat ground pork at freezing and refrigeration temperatures

Gamma radiation effectively controls Listeria monocytogenes in uncooked and in ready-to-eat foods. This study was conducted to determine if gamma radiation could be used to control L. monocytogenes in ground pork. Ground pork was contaminated with L. monocytogenes, kept at refrigeration (4 degrees C), chilling (0 degrees C), and freezing (-18 degrees C) temperatures overnight, exposed to gamma radiation and stored at 4 degrees C for 7 days, and at 0 and -18 degrees C for 60 days. Following irradiation, the meat was assayed for L. monocytogenes viable counts and lipid oxidation. A triangle test was performed to determine if sausage made from the irradiated and nonirradiated ground pork differed in sensory quality. It was observed that a 5-log reduction of L. monocytogenes viable counts would require a 3.0-kGy radiation dose. The results of a 60-day storage study of ground pork inoculated with 10(5) to 10(6) CFU of L. monocytogenes per gram indicated that counts for nonirradiated meat remained fairly constant at refrigeration, chilling, and freezing temperatures. However, irradiation of ground pork at 3.0 kGy could inactivate L. monocytogenes totally in ground pork subsequently held at all the temperatures used in this study. Lipid oxidation measurements, as determined by the thiobarbituric acid-reactive substance assay, ranged from 0.16 nmol/g for nonirradiated ground pork and 0.20 nmol/g for meat irradiated at 3.0 kGy. Sensory panelists could distinguish between irradiated and nonirradiated sausage but were divided on whether irradiation adversely affected the sausage quality. Our results suggest that gamma radiation could be useful to control L. monocytogenes in ground pork and improve the safety of ground pork products.     

Irradiation to kill Escherichia coli O157:H7 and Salmonella on ready-to-eat radish and mung bean sprouts

A study was carried out to evaluate the effectiveness of ionizing radiation in eliminating Escherichia coli O157:H7 and Salmonella on commercial ready-to-eat radish and mung bean sprouts and to assess the chemical and physical quality of these sprouts. The use of ionizing radiation was investigated as a means of reducing or totally inactivating these pathogens, if present, on the sprouts. Treatment of mung bean and radish sprouts with a dose of 1.5 and 2.0 kGy, respectively, significantly reduced E. coli O157:H7 and Salmonella to nondetectable limits. The total vitamin C content was gradually reduced with the increase in irradiation dose (P < 0.0001). However, the effect of storage interval on the loss of vitamin C was nonsignificant for radish sprouts and significant for mung bean sprouts (P < 0.04). The color, firmness, and overall visual quality of the tested sprouts were acceptable when effective doses were applied to both radish and mung bean sprouts. Therefore, ionizing radiation could be useful in reducing the population of pathogens on sprouts and yet retain acceptable quality parameters.     

Experimental investigation of new concentration measurements using nonlinear dynamics through laser-induced thermal lens oscillation

The laser-induced thermal lens oscillation that is generated in an organic solution by Ar-ion laser irradiation was studied as a nonlinear dynamic system. The different dynamic states depend on three control parameters: laser beam power (P), depth (d) from a surface to a laser beam position, and solvent concentration. The transitions of dynamic states including several complicated states, for example, periodic, double periodic, were investigated by varying the parameters (P, d) for 27%, 30%, and 33% of tri-n-butyl phosphate solution diluted with n-dodecane. It was found that these transitions were strongly dependent on the concentration of the TBP solution. Based on this result, we also propose an application to solvent concentration measurement with a difference of 3%.     

Determination of the temperature of bremsstrahlung photon generated by ultraintense laser using various thickness attenuators

We evaluate the simplified method using the Lambert-Beer law to measure the temperature of bremsstrahlung photon generated by an ultraintense laser. Analytical values are compared to the results of the Monte Carlo calculation of GEANT4 and they agreed very well on the condition of the appropriate distance between the attenuator and the detector. We performed the experiment to measure the temperature of bremsstrahlung x-ray emitted from a metal target irradiated by a Ti:sapphire laser with 76 mJ, 72 fs, 2.2 × 10(18) W∕cm(2). For a Cu target of 30 μm thick, the photon temperature was reasonably determined to be 0.18 MeV, which is in good agreement with previous studies.     

Sprout inhibition of potatoes with soft‐electron (low‐energy electron beams)

The surfaces of potatoes were irradiated with electrons of different energy levels, and the effects on sprouting were investigated. Electrons at 270 keV or higher effectively inhibited sprouting of four cultivars of potatoes, cvs Danshaku, Hokkaikogane, Toyoshiro and May Queen, even after storage at 23 °C for 4 months. Sugar contents in tubers treated with 270‐keV electrons were lower after storage for 3 months than their levels before electron treatment. The levels of glucose, fructose and sucrose were significantly lower in the tubers treated with 270‐keV electrons than in low temperature (5 °C)‐stored tubers. The results indicate the potential of low energy electron treatment for the shelf‐life extension of potatoes as an alternative to treatments with gamma‐rays or chemicals. Copyright © 2004 Society of Chemical Industry     

Determination of tetrahydro-beta-carbolines in rat brain by gas chromatography-negative-ion chemical ionization mass spectrometry without interference from artifactual formation

This paper describes a quantitative method for neuroactive alkaloids, 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) and 1,2,3,4-tetrahydro-beta-carboline (TBC), in rat brain by gas chromatography-negative-ion chemical ionization mass spectrometry (GC-NICIMS). After addition of tetradeuterated MTBC and TBC (internal standards), the samples were subjected to deproteinization, reaction with fluorescamine, solvent extractions, trifluoroacetylation and GC-NICIMS analysis. In contrast to the other previous methods, the artifactual formation during analysis did not interfere with the determination of MTBC and TBC because their precursor tryptamine was removed as a fluorescamine derivative from the analytical system at the first step of pretreatment. MTBC and TBC were specifically and reliably determined in the range of pg-ng/sample. Application of the proposed method has revealed that the MTBC and TBC contents in rat brain significantly increase after intraperitoneal administration of MTBC and TBC, indicating their ability to easily cross the blood-brain barrier.     

Development and single laboratory validation for thermoluminescence detection of irradiated foods using X-ray irradiation

The thermoluminescence (TL) method using X-rays was investigated for the purpose of detection of irradiated food, and the method was validated at a single laboratory level. A small X-ray irradiator was developed as an alternative radiation source for normalization, and X-ray irradiation conditions equivalent to gamma-ray irradiation from (60)Co were established. Gamma-ray irradiated spices were used for the method validation. The detection limits (MDL) and lower limit of integrated TL intensities (MDL×10) for the spices were checked and the separation of silicate minerals from the spices was confirmed to be sufficient for TL analysis. There was no significant difference in TL glow ratio obtained using two sets of X-ray irradiation equipment including the newly developed equipment. Repeatability and intermediate precision showed no influence of analysts, X-ray irradiation equipments, or measurement days on the TL ratios. From these results, this detection method was validated in a single laboratory.