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The scintillation response to an α source (241Am) and the ionization yield in pure gaseous xenon and its mixtures with 0.2–2% of methane were measured at a pressure of 26 atm and different values of reduced electric field E/N. Both light and ionization yields in xenon were shown to decrease with increasing percentage of methane.

The type XL cross-axis coil planet centrifuge (CPC) was successfully utilized for purification of cholinesterase (ChE) from human serum by countercurrent chromatography (CCC). Aqueous-aqueous polymer phase systems composed of polyethylene glycol-potassium phosphate buffers were tested at various pHs, ranging from 6.8 to 9.2 for the distribution ratios (D) of ChE, human serum albumin, α- and γ-globulins. The CCC separation was performed with optimized polymer phase systems in two different coiled columns. The best purification was achieved with 16.0% PEG 600–12.5% potassium phosphate at pH 9.2, by eluting the lower phase at 0.5 mL/min through the small capacity column in which ChE was purified directly from human serum within 2h. The ChE fractions confirmed by the enzymatic activity were free of serum proteins by SDS PAGE analysis.

We summarize the present R&D status of high-pressure xenon time projection chamber (HPXe-TPC) which is a new gamma-ray camera for planetary science mission.

A 64-year-old male was admitted to our hospital with complaints of the development of high fever, cough and dyspnea 5-6 hours after painting automobiles. His chest X-ray film showed interstitial shadows in both lungs. Pulmonary function test demonstrated reduction of diffusion capacity; and blood gas analysis demonstrated hypoxemia and an increase in alveolar-arterial oxygen tension difference. Marked lymphocytosis and a striking decrease in CD4/CD8 ratio were observed in the bronchoalveolar lavage fluid. Transbronchial lung biopsy specimens showed alveolitis and Masson's bodies. We suspected that the patient was suffering from hypersensitivity pneumonitis induced by isocyanates contained in the urethane paint he used. Immunological studies were performed using chemical compounds of three species of isocyanate molecules (TDI, MDI, HDI) and human serum albumin (HSA). The results were as follows: skin tests were positive for TDI-HSA and MDI-HSA; lymphocyte-stimulation tests on peripheral blood were positive for TDI-HSA; precipitation reaction was negative for all the isocyanates studies; enzyme-linked immunosorbent assay (ELISA) demonstrated the existence of specific IgG antibodies for TDI, MDI and HDI; inhalation challenge test by TDI-HSA was negative, but environmental provocation was considered to be positive. We diagnosed his pulmonary disorder as hypersensitivity pneumonitis due to isocyanates. Type III and Type IV allergic reactions of Gell-Coombs were suggested to be involved in the pathogenesis, however, there remains the possibility that the instability of isocyanate compounds as antigen modified the results of our immunological studies.

We have obtained the ratio of the transverse diffusion coefficient to the mobility of electrons multiplied by the elementary charge, in Xe and Xe+H2 under electric fields at a higher pressure of 1 MPa in comparison with those in preceding experiments. The results show that the density effect (nonlinear effect) of the ratio in both pure Xe and Xe+H2 is ≤15% below 1 MPa over the reduced electric field range from 0.08 to 0.6×10-17 V·cm2. We also found that the diffusion of an electron swarm is suppressed by adding trace amount of hydrogen to high-pressure xenon gas. We discuss the application of Xe+H2 gas to a new gamma-ray camera.

High-pressure xenon time projection chamber (HPXe-TPC) is a sophisticated detector, which can determine not only an energy of gamma ray but also its arrival direction by using Compton scattering. Diffusion of electrons and scintillation yield in Xe and Xe+H/sub 2/ mixture have been investigated to realize a HPXe-TPC. The transverse characteristic energy of electrons in Xe-H/sub 2/ mixture (H/sub 2/ 0.44%) was reduced to about 40% against that of pure Xe at 1.0 MPa. Scintillation yields by alpha-particles (/sup 241/Am) in Xe+H/sub 2/ mixture (H/sub 2/ /spl sim/ 0.23-5.7%) at 2.6 MPa were obtained as a function of E/N. The scintillation yields in Xe+H/sub 2/ mixture at 2.6 MPa and at E/N = 0.3/spl times/10/sup -17/ Vcm/sup 2/ were luminous enough to generate a trigger signal of a HPXe-TPC. It is found that doping hydrogen into xenon is effective to prevent the degradation of angular resolution of a HPXe-TPC.