Compatibility of alkaline earth metal (Mg, Ca, Sr)-doped lanthanum chromites as separators in planar-type high-temperature solid oxide fuel cells

The mechanical, electrical and thermal properties of alkaline earth metal (Mg, Ca and Sr)-doped LaCrO₃ have been examined as separators in planar-type high-temperature solid oxide fuel cells. The maximum three-point bending strength at 1000°C in air was measured and found to be 186 MPa for LaCr_0.9Mg_0.1O₃, 36 MPa for La_0.9Ca_0.1CrO₃ and 77 MPa for La_0.9Sr_0.1CrO₃. The La_0.8Sr_0.2CrO₃ separator placed in both an oxidizing and a reducing environment at 1000°C showed almost the same electrical conductivities of the H₂ atmosphere, and the conductivity was independent of sample thickness in the range 0.5–3.0 mm. For all the doped LaCrO₃ perovskites, a difference between the thermal expansion behaviours of air and the H₂ atmosphere was observed. In particular, the thermal expansion slope for the first heating cycle under the H₂ atmosphere showed a marked change. The volume changes were due to the formation of oxygen defects in the perovskite structure. This revised version was published online in November 2006 with corrections to the Cover Date.     

Acetazolamide challenge and technetium-99m-ECD versus iodine-123-IMP SPECT in chronic occlusive cerebrovascular disease

We compared the acetazolamide challenge test using 99mTc-ECD SPECT and 123I-IMP SPECT images in patients with chronic occlusive cerebrovascular disease. We also evaluated the usefulness of linearization correction for acetazolamide challenge test of 99mTc-ECD SPECT. METHODS: Twenty patients with unilateral chronic occlusive cerebrovascular disease (10 patients had middle cerebral arterial lesion and 10 had internal carotid lesion) were included in the study. Split-dose (a dose fractioning was 1:2), and sequential SPECT technique was used for 99mTc-ECD SPECT studies while only acetazolamide challenge test studies for 123I-IMP SPECT were performed. Permeability surface area product model (PS model) and back-diffusion model (Lassen's correction) were used for linearization correction of acetazolamide challenge with 99mTc-ECD SPECT. RESULTS: Six of 16 patients with reduced vasodilatory capacity in 123I-IMP SPECT were underestimated by 99mTc-ECD SPECT acetazolamide challenge test. Relative ECD uptake normalized by cerebellar uptake compared with IMP uptake showed a nonlinear relationship, indicating relatively less uptake in high flow range. The underestimations of limited vasodilatory capacity observed in 99mTc-ECD SPECT without linearization correction was modified by linearization algorithm. However, the effect of correction based on PS model was superior than that of Lassen's correction. The corrected 99mTc-ECD uptake ratio, based on PS model, and IMP uptake ratio demonstrated a better linear relationship than that of Lassen's correction. CONCLUSION: Technetium-99m ECD SPECT corrected based on the PS model is a better method of linearization for evaluating cerebrovascular reserve using acetazolamide challenge.     

Measurements ofPVTx properties of refrigerant mixture HFC-32+HFC-125 in the gaseous phase

The experimental 156PVTx properties of an important binary refrigerant mixture, HFC-32 (difluoromethane)+HFC-125 (pentafluorethane), have been measured for three compositions, i.e., 50, 60, and 80 wt% HFC-32, by a constant-mass-method coupled with expansion procedure in an extensive range of temperaturesT from 320 to 440 K, of pressuresP from 1.8 to 5.3 M Pa, and of densities p from 50 to 124 kg · m^–3. The experimental uncertainties of the present measurements are estimated to be within ±7 mK in temperature, ±2 kPa in pressure, ±0.2% in density and ±0.02 wt% of HFC-32. The sample purities are 99.998 wt% for HFC-32 and 99.99 wt% for HFC-125. Seventy-eight second and third virial coeflicients for temperatures from 320 to 440 K have been determined by the present measurements.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Hematopoietic and lymphopoietic responses in human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor transgenic mice injected with human GM-CSF

Using a clonal assay of bone marrow (BM) cells from transgenic mice (Tg-mice) expressing the human granulocyte-macrophage colony-stimulating factor receptor (hGM-CSFR), we found in earlier studies that hGM-CSF alone supported the development not only of granulocyte-macrophage colonies, but also of erythrocytes, megakaryocytes, mast cells, blast cells, and mixed hematopoietic colonies. In this report, we evaluated the in vivo effects of hGM-CSF on hematopoietic and lymphopoietic responses in the hGM-CSFR Tg-mice. Administration of this factor to Tg-mice resulted in dose-dependent increases in numbers of reticulocytes and white blood cells (WBCs) in the peripheral blood. Morphological analysis of WBCs showed that the numbers of all types of the cell, including neutrophils, eosinophils, monocytes, and lymphocytes increased; the most remarkable being in lymphocytes that contained a number of large granular lymphocytes (LGLs) in addition to mature T and B cells. However, total cellularity of the BM of the Tg-mice decreased in a dose-dependent manner when hGM-CSF was injected. In sharp contrast to the BM, spleens of the Tg-mice were grossly enlarged. Although all types of blood cells and hematopoietic progenitors increased in the spleen, erythroid cells and their progenitors showed the most significant increase. Increased numbers of megakaryocytes and LGLs were also observed in spleen and liver of the treated Tg-mice. Flow cytometric analysis showed that LGLs expanded in Tg-mice expressed Mac-1+ CD3- NK1.1+. The thymus of Tg-mice treated with hGM-CSF exhibited a dose-dependent shrinkage and a remarkable decrease in CD4+ CD8+ cells. Thus, hGM-CSF stimulated not only myelopoiesis but also erythropoiesis and megakaryopoiesis of hGM-CSFR Tg-mice in vivo, in accordance with our reported in vitro findings. In addition, hGM-CSF affected the development of lymphoid cells, including natural killer cells of these Tg-mice.     

Pharmacological study on circadian rhythms in mammals

Living organisms including humans drive circadian rhythm, and this rhythm influences the social structure and daily life of human beings. The suprachiasmatic nucleus (SCN) has been established as a pacemaker for mammalian circadian rhythm. There are many kinds of neurotransmitters and neuromodulators in this nucleus. The circadian systems are involved in oscillation, input (entrainment) and output (overt rhythm). Therefore in this review, pharmacological characteristics of circadian systems in relation to the SCN are discussed by focussing especially upon the roles of various neurotransmitters and modulators.     

Theoretical and Experimental Study of Water Transport in a Hollow Cylinder Applied to the Drying of Round Squid Mantle

Until now, attention has been focused solely in the drying of squid mantle from an experimental point of view, neglecting the transport phenomenon studies of water in squid muscle. This work studies the drying of squid mantle (Loligo brasiliensis), previously salted and smoked by liquid smoking (hickory extract), using a tubular dryer in closed cycle with a silicagel fixed bed in series. The mass transfer phenomenon during drying was studied, based on the Fick's second law, with the effective diffusivity supposed constant, which enabled an analytical solution to the problem. The drying curve calculated with the resulting equation was compared with experimental data. The model was applied to a hollow cylinder geometry (round squid mantle), with its internal surface isolated from the drying environment by a plastic film. The latter was given a tubular form and introduced inside the mantle cavity (impervious wall boundary condition).     

An equation of state for 1,1-difluroethane (HFC 152a)

An equation of state for 1,1-difluoroethane (HFC 152a, CH₃CHF₂) has been developed on the basis of reliable experimental data including PVT, liquid C_p, and saturated-liquid-density data measured by our group. It is a non-dimensionalized virial equation whose functional form is the same as that originally developed for 1,1,1,2-tetrafluoroethane (HFC 134a) in our group. The effective range is for pressures up to 15 MPa, temperatures from 230 to 450 K, and densities to 1000 kg m⁻³. The equation represents reliable PVT measurements within ± 1% in pressure for the superheated vapour and supercritical fluid, while within ±0.5% in density for the compressed liquid. In addition, it should be noted that the equation represents the other essential thermodynamic properties including vapour pressures, saturated-liquid/ vapour densities, isobaric/isochoric specific heats and sound velocity in both the liquid and gaseous phase of HFC 152a.     

KGa-priderite and related compound for the selective reduction of nitrogen monoxide with propylene

The catalytic activity of KGa-priderite, K_1.6Ga_1.6Ti_6.4O₁₆, and its related compound KGa₈Ga₉Ti₁₅O₅₆ was investigated for the selective reduction of nitrogen monoxide (NO) with propylene (C₃H₆) in the presence of high oxygen concentrations. The KGa-priderite showed significant activity during this reaction, but the related compound showed only a little activity. These compounds are quite different from the conventional catalysts for NO_x selective reduction and are characterized by the fact that their properties are free from the effects of solid acidity and support metals. This difference was attributable to the NO desorption rate at the surface of these compounds. It has become clear that the KGa-priderite catalyst remarkably adsorbed NO, and it is suggested that the amount of NO adsorbed and the amount of catalytic activity are able to be increased by the design of priderite structure.     

A sensorless brushless dc motor system

This paper describes a brushless dc motor system without position or speed sensor. The brushless motor consists of a permanent magnet synchronous motor and a voltage-source inverter capable of controlling the amplitude and frequency of voltage. The rectangular-shaped stator current with a conducting interval of 120° (electrical) is controlled to be in phase with the trapezoidal back electromotive force. This results in producing maximum torque. Variable speed is achieved by adjusting the average motor voltage similarly to chopper control of dc motors. In this paper, two sensorless position detecting methods, i.e., an “indirect method” suited for the lower-speed range and a “direct method” suited for the higher-speed range are proposed. The combination of the two makes it possible to detect the rotor position over a wide-speed range. Furthermore, a speed-sen-sorless PLL control is proposed in applying the principle of the direct method. Experimental results obtained from a prototype brushless dc motor are shown to confirm the validity of the sensorless drive. The starting procedure of the motor also is discussed because it is impossible to detect the rotor position at a standstill.     

Progressive bronchial obstruction during the acute stage of respiratory tract infection in asthmatic children

To study the time-course of infectious asthma, we retrospectively examined FEV1 from 5 days before to 10 days after the onset of illness in 31 asthmatic children (20 boys and 11 girls), aged 8 to 12 years. Infections were confirmed by a rise of at least fourfold in serum compliment fixation titers (respiratory syncytial virus, adenovirus, and Mycoplasma pneumoniae) and hemoagglutination inhibition titers (parainfluenza virus types 1, 2, and 3). All the patients had 20 percent or more fall in FEV1 from baseline value during acute phase, but were clinically tolerable and required minimum or no bronchodilators. Regardless of infectious agent, FEV1 began to fall on the first disease day or the previous day, and deteriorate for the first few days. Mean(SD) maximum fall in FEV1 ranged from 39(12) percent to 45(20) percent. Thereafter, FEV1 began to improve and returned to the preillness level by the seventh to tenth day. These results suggest that progressive bronchial obstruction may be inevitable during the acute stage of any infectious asthma.