Microdosimetric distribution of protons,Ep = 19-65 MeV,measured with a low pressure proportional counter

Microdosimetric measurements of 19, 32, 43, 55, and 65 MeV protons were carried out with the A-150-walled low pressure proportional counter (LPPC). The spectra are deconvoluted into three components, which are energy loss by directly incident protons, secondary electrons, and scattered protons and heavy charged particle (including protons) produced by proton nuclear reactions with the TE wall. Dose-mean lineal energies of protons are large as usual, because larger lineal energies by proton reaction events are affected.     

Space charge behavior in low density polyethylene at pre-breakdown

It has been known that the electrical breakdown of insulating materials is strongly affected by the formation of space charge in the bulk of the materials. Many researchers have attempted to study the relationship between the space charge and the breakdown; however, it has not been clarified yet. Although the pulsed electroacoustic (PEA) method has been widely used to observe space charge profiles, previous works have not shown clear evidence of the influence of the space charge on the breakdown. Therefore, we have developed a new PEA system with an interval of 0.5 ms to observe the space charge distribution continuously under the ultra-high electric field. Using this system, we observed the space charge dynamics in the low-density polyethylene (LDPE) at and around the breakdown. We also investigated the dependence of the applied electric field on space charge behavior. From the results, it is found that the injected charge packet moved faster and deeper under a relatively lower electric field rather than that under a higher electric field. Furthermore, we found that the maximum electric field in each specimen was almost the same when the breakdown happened in a specimen.     

Preparation of L-talose and D-gulose from L-tagatose and D-sorbose, respectively, using immobilized L-rhamnose isomerase

L-rhamnose isomerase of Pseudomonas sp. LL172 immobilized on BCW 2603 Chitopearl beads was used to produce L-talose and D-gulose. At equilibrium, the production yields of L-talose and D-gulose were determined to be 12 and 10% from L-tagatose and D-sorbose, respectively. The crystallized products were confirmed by HPLC, IR and NMR spectra, and optical rotation measurement analyses.     

Dithiobissuccinimidyl propionate as an anchor for assembling peroxidases at electrodes surfaces and its application in a H2O2 biosensor

Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands.     

Endothelin-1 secretion from cultured vascular endothelial cells of DOCA-salt hypertensive rats

The profile of endothelin-1 (ET-1) release from cultured vascular endothelial cells (ECs) obtained from deoxycorticosterone acetate (DOCA)-salt hypertensive rats, was examined and compared with that from normotensive sham rats. ET-1 release from ECs was increased in a time-dependent manner, and the level of DOCA-salt hypertensive rats was higher than that of sham rats. Incubation of ECs with transforming growth factor (TGF)-beta 1 or thrombin resulted in a significant increase in the ET-1 release, while FK409, a novel nitric oxide donor, produced a dose-dependent decrease in the release. In the case of ECs from DOCA-salt hypertensive rats, the potencies of TGF-beta 1- or thrombin-induced action was much less than that seen with sham rats, while the difference of reactivity to FK409 was not observed between ECs of DOCA-salt rats and sham rats. Thus, ET-1 production in ECs appears to be up-regulated in DOCA-salt hypertensive rats. In addition, there seems to be an abnormalities in the signaling pathway via TGF-beta 1- or thrombin-induced enhancement of ET-1 production in ECs of DOCA-salt hypertensive rats.     

Surgical treatment of Cronkhite-Canada syndrome associated with protein-losing enteropathy: report of a case

PURPOSE: The case of a patient with Cronkhite-Canada syndrome, who developed a protein-losing enteropathy, is reported. METHODS: After localization of the protein-losing region, a right colectomy was performed. RESULTS: Hypoproteinemia and ectodermal changes improved postoperatively. CONCLUSIONS: Surgery is an effective treatment for protein-losing enteropathy in Cronkhite-Canada syndrome. Ectodermal changes improve after correcting malnutrition.     

Evaluation of indoor gamma radiation dose in dwellings

The use of materials containing naturally occurring radionuclides for house construction may enhance the natural radiation background to which some population groups are exposed. External exposure results from gamma emitter radionuclides existing in the walls, floor and ceiling. Mathematical models can be used to predict external dose rates inside a room, provided the compartment geometry and the radionuclide concentration activities are known. This paper presents a methodology and a computer code for theoretical evaluation of indoor external gamma doses in the air. The room was modelled as three pairs of rectangular slabs of finite thickness. Doses were evaluated by applying a photon transport model, taking into account self-absorption and radiation build-up. Calculations were performed for 40K, 226Ra and 232Th, considering concrete walls. The results obtained show good agreement with those reported in the literature. Dose conversion factors are presented in a practical manner, ready to use for radiological impact screening.