Carbon Dioxide Sensor Mechanism of Porous Hydroxyapatite Ceramics

Hydroxyapatite and Cl⁻ -containing hydroxyapatite powders are prepared and characterized. Reversible substitution of CO^2-₃ for OH⁻ at the surface is presumed to be responsible for the sensor function. The role of Cl⁻, which is necessary to realize the sensor function and is incorporated during soaking treatment, is considered as follows. It may reduce the strain caused by the incorporation of CO^2-₃ (which is larger than OH⁻), and, hence, promote the reversible substitution reaction. This behavior is presumed because Cl⁻ -containing hydroxyapatite samples exhibit sensor characteristics typical of CO₂ without any treatment.     

Influence of low temperature working on microstructure and mechanical properties of AI-7Si-(Fe) alloys

Changes in the microstructure and mechanical properties of Al-7Si-(Fe) alloys by low temperature working have been investigated. The size and shape of eutectic Si and intermetallic AlSiFe compound were controlled by the low temperature working process. This process consisted of repeated cold working at 77 K and recovery treatment at 793 K. By applying this process to the Al-7Si-1Fe alloy, the eutectic Si and acicular Fe compound(β-AlSiFe) phases were broken down to the size of 2-3 μm, with spherical shape. The refined particles were uniformly distributed, and a fine microstructure was obtained. The strength and elongation of Al-7Si-1Fe alloy increased as the temperature was lowered due to the microstructural refinement. This elongation was well reflected in the fracture surface.     

Neuromelanin in Parkinson’s Disease: Tyrosine Hydroxylase and Tyrosinase

Parkinson’s disease (PD) is an aging-related disease and the second most common neurodegenerative disease after Alzheimer’s disease. The main symptoms of PD are movement disorders accompanied with deficiency of neurotransmitter dopamine (DA) in the striatum due to cell death of the nigrostriatal DA neurons. Two main histopathological hallmarks exist in PD: cytosolic inclusion bodies termed Lewy bodies that mainly consist of α-synuclein protein, the oligomers of which produced by misfolding are regarded to be neurotoxic, causing DA cell death; and black pigments termed neuromelanin (NM) that are contained in DA neurons and markedly decrease in PD. The synthesis of human NM is regarded to be similar to that of melanin in melanocytes; melanin synthesis in skin is via DOPAquinone (DQ) by tyrosinase, whereas NM synthesis in DA neurons is via DAquinone (DAQ) by tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). DA in cytoplasm is highly reactive and is assumed to be oxidized spontaneously or by an unidentified tyrosinase to DAQ and then, synthesized to NM. Intracellular NM accumulation above a specific threshold has been reported to be associated with DA neuron death and PD phenotypes. This review reports recent progress in the biosynthesis and pathophysiology of NM in PD.     

Thermoelectric properties of β-FeSi2 with B4C and BN dispersion by mechanical alloying

The B₄C- and BN-dispersed -FeSi₂ thermoelectric materials were synthesized by mechanical alloying and subsequent hot pressing. The effects of the B₄C and BN dispersion on the thermoelectric properties, such as Seebeck coefficient, electrical resistivity and thermal conductivity etc., of the -FeSi₂ were investigated. For the sample with B₄C and BN addition, a larger amount of the residual phase was detected in the X-ray diffraction patterns than the sample without addition. In the case of the BN addition, the Seebeck coefficient was enhanced by BN addition above 700 K, and the electrical resistivity also increased with increasing amount of BN. This is considered to result from doping of a small amount of B into the phase due to partial decomposition of the BN phase. The fine dispersion of BN particles in the phase matrix was quite effective for reducing the thermal conductivity as compared to the B₄C addition over the entire temperature range. The figure of merit, Z, of the -FeSi₂ was significantly enhanced by BN addition.     

Protective layer for high‐efficiency PDPs driven at low voltage

Abstract— The sustain pulse voltage of a panel for 66‐kPa Ne + Xe (5–30%) with an (SrCa)O protective layer is 20–40% lower than that with an MgO protective layer. The luminous efficiency of the panel with a Ne + Xe (30%) (SrCa)O protective layer is 1.5 times that of the conventional panel with a Ne + Xe (10%) MgO protective layer; the sustain pulse voltages of these panels are almost the same. The power loss caused by panel capacitance is proportional to the second power of the sustain pulse voltage. Using the (SrCa)O protective layer for Xe (5–30%), the power loss is reduced by 35–60% compared with the MgO protective layer. It follows that, using the (SrCa)O protective layer, we can increase the Xe content with little power loss and thus achieve high‐efficiency PDPs. As for MgO and CaO with Xe ions, electrons are probably ejected from only the defect states. On the other hand, as for the SrO with Xe ions, it is likely that electrons can be ejected from not only defect states but also the valance band. This seems to be the reason why the driving voltage is lower with the (SrCa)O protective layer than with the MgO protective layer.     

A method for calculating the electromagnetic noise of a motor-driven thin blade fan

An urgent need exists to develop a method of predicting the noise level of a blade fan attached to a motor shaft. To satisfy this requirement, we developed a method for calculating the sound generated when a rotating blade is excited by the torque pulsation of a motor. The sound pressure values calculated by the new method for a rotating blade were found to correspond well with experimentally measured ones.     

Role of Stripes in Spin and Charge Dynamics of Underdoped La2−x Sr x CuO4

We investigate the electronic states of underdoped La _2–x Sr _x CuO ₄ (LSCO) by using a microscopic model, i.e., t-t-t-J model, containing charge stripes. The numerically exact diagonalization calculation is employed on small clusters. The physical properties observed in the angle-resolved photoemission and optical conductivity experiments are consistently explained in the model with vertical stripes, but not diagonal ones. These results demonstrate a crucial role of the vertical stripes in underdoped LSCO.     

Effect of anti-IL-4 and anti-IL-5 antibodies on allergic airway hyperresponsiveness in mice

In order to study the role of IL-4 and IL-5 in allergen-induced airway hyperresponsiveness in mice, the effect of the combined administration of anti-IL-4 and anti-IL-5 monoclonal antibodies (mAbs) on IgE response, airway inflammation and airway hyperresponsiveness was studied in sensitized Balb/c mice. Three inhalations of antigen caused an increase in the number of eosinophils in bronchoalveolar lavage fluid and in airway responsiveness to acetylcholine, with a significant elevation in the serum antigen-specific IgE level. Anti-IL-4 mAb inhibited IgE production but did not affect airway eosinophilia or hyperresponsiveness. Moreover, anti-IL-5 mAb inhibited airway eosinophilia but did not affect IgE production or airway hyperresponsiveness. The combined administration of anti-IL4 and anti-IL-5 mAbs, however, inhibited IgE antibody production, airway eosinophilia and hyperresponsiveness. These results suggest that inhibitory action of IL-4 and IL-5 in combination can effectively suppress the onset of antigen-induced airway hyperresponsiveness in mice.     

Endothelin converting enzyme inhibitor protects development of right ventricular overload and medial thickening of pulmonary arteries in rats with monocrotaline-induced pulmonary hypertension

We evaluated the effects of FR901533, endothelin converting enzyme inhibitor, on development of right ventricular overload and medial thickening of pulmonary arteries in rats with monocrotaline-induced pulmonary hypertension. Pulmonary hypertension was induced by a single injection of monocrotaline (80 mg/kg). Twenty-four hours later (day 1), continuous subcutaneous injection of FR901533 (100 mg/kg/day) was started. Right ventricular systolic pressure, mass ratio of right ventricle to left ventricle, right ventricular wall thickness, right ventricular myocardial fiber diameter, percent medial thickness, and percent smooth muscle area in pulmonary arteries were significantly less in rats that received FR901533 than in the control with monocrotaline on day 28. Both immunoreactivities of endothelin-1 in pulmonary arteries and plasma endothelin-1 levels were observed significantly less in rats treated with FR901533 than in the control with monocrotaline. There were significant increased immunoreactivities of endothelin-B receptor in pulmonary arteries in rats that received FR901533 as compared with those in the control with monocrotaline. FR901533 (100 mg/kg/day), protected the development of right ventricular overload and medial thickening of pulmonary arteries in a rat model of pulmonary hypertension.