Possible participation of cyclooxygenase-2 in the recurrence of allergic inflammation in rats

The possible involvement of purines and/or nitric oxide (NO) in the gamma-aminobutyric acid (GABA)A receptor-mediated effects on the spontaneous activity of isolated preparations from longitudinal and circular muscles of cat terminal ileum was investigated. GABA had biphasic effects, which were neurogenic and muscarinic. ATP and adenosine dose dependently inhibited the activity of the muscles. A contractile response evoked by the nucleotide only was also observed. The effects of the purines were equipotent and resistant to Nomega-nitro-L-arginine (L-NNA), tetrodotoxin and to desensitization by alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-meATP), except for the contractile effect of ATP, which was abolished by alpha,beta-meATP. Pretreatment of the preparations with ATP or adenosine produced: (i) desensitization to the effects of the respective purinoceptor agonist only; and (ii) suppression of the GABA-induced responses of longitudinal and circular muscles. Hemoglobin and L-NNA greatly reduced or completely blocked the GABA(A)-induced relaxation and decreased the GABA(A)-induced contraction. Our results indicate that purines and NO, to a different extent, mediate the relaxant phase of the GABA effects in both layers. Interactions between muscarinic cholinoceptors and GABA-nitrergic pathway and a concomitant activation of postjunctional P1 and P2y purinoceptors are suggested to explain the prejunctional biphasic effects of GABA.     

Enacting new temporal boundaries: the role of mobile phones

This paper examines how the use of mobile phones influences the temporal boundaries that people enact in order to regulate and coordinate their work and non-work activities. We investigate both the structural and interpretive aspects of socio-temporal order, so as to gain a fuller appreciation of the changes induced by the use of mobile phones. With specific reference to professionals working in traditional, physically based and hierarchically structured organizations, we found that mobile phone users are becoming more vulnerable to organizational claims and that as a result ‘the office’ is always present as professionals, because of the use of mobile phones, become available ‘anytime’. This is enabled by the characteristics of the technology itself but also by users’ own behaviour. In the paper, we discuss the properties of the emerging socio-temporal order and show how mobile phones may render the management of the social spheres in which professionals participate more challenging.     

Possibility of a Chiral Phase Transition in Two-Dimensional 3He Solid

We study a Hamiltonian of S = 1/2 spins with two-, three and four-spin exchange interactions on the triangular lattice as a possible model of the nuclear magnetism of solid ³ He layers. The spin wave theory shows that the tetrahedral ground state, which was shown to be favoured by the four-spin exchange interaction in our previous paper, is stable against quantum fluctuations in some parameter region. Since this state has a scalar chiral long-range order, a phase transition occurs at a finite temperature even though the Hamiltonian has a full rotational symmetry in the spin space. Critical behavior of this phase transition was examined by classical Monte Carlo simulations. The specific heat diverges much more strongly than that of the 2D Ising model.     

A 25.5 MHz double-coaxial λ/4-resonator as a rebuncher in heavy ion linac system

A 25.5 MHz double-coaxial λ/4-resonator has been constructed to be used as a rebuncher between a 25.5 MHz RFQ linac and a 51 MHz interdigital-H linac for the acceleration of short-lived nuclei. By employing a double coaxial structure, the resonator length is only 130 cm; the length of the natural λ/4-resonator is 294 cm. The resonator, 69 cm in inner diameter, has six acceleration gaps. The bare shunt impedance is 40.6 MΩ/m. The ions with a charge-to-mass ratio 1/10 can be rebunched by feeding an rf power of 1.4 kW.     

Growth and electrical properties of ZnO thin films deposited by novel ion plating method

The URT(Uramoto-gun with Tanaka magnetic field)-IP(ion plating) method is a technique for depositing a thin film on a substrate. This method offers the advantage of low-ion damage, low deposition temperatures, large area deposition and high growth rates. Ga-doped ZnO thin films were grown using the URT-IP method, and the material properties were evaluated. The quality of ZnO thin films grown by the URT-IP method was found to be sensitive to oxygen supply during growth. It was observed that the saturation point of the growth rate corresponding to the optimum oxygen supply leads to the best electrical properties. The profiles of the dependence of film properties on oxygen supply revealed a part of growth mechanism of the URT-IP method.     

Oxidative degradation of polymers. II. Thermal oxidative degradation of atactic polypropylene in solution under pressure

Atactic polypropylene was oxidized in solution in the presence and absence of radical initiator over the temperature range of 140° to 200°C under oxygen pressure of 3.3 to 12.4 kg/cm², and the effects of metal catalyst and additives on the rate, products, and change in molecular weight distribution were measured. The synergistic effect was observed with cobalt and managanese salts. The deactivation of the metal catalyst was suppressed by the addition of acetic acid and acetic anhydride as solvent. The rate of oxidation increased with increasing temperature, but the decrease in molecular weight was nevertheless not so significant as to give many low-boiling products. However, the production of mixtures of acid, ketone, alcohol, and ester with molecular weights of several hundreds was promising. The refractive index of polypropylene decreased markedly as the oxidation proceeded, and the complications involved in the determination of the change in molecular weight distribution measured by gel permeation chromatography are discussed.     

Long life sealed nickel-zinc cell using a new separator

Because of internal shorting due to zinc (Zn) dendrite formation at the Zn electrode, nickel-zinc (NiZn) secondary cell cycle life is somewhat less than the NiCd cell cycle life. To solve this problem, a new kind of separator was developed which consisted of nylon non-woven cloth coated with poly(vinyl alcohol) (PVA) containing boric acid. This separator has a high ionic conductivity, but is resistant to zincate ion penetration. A large number of additives, effective for Zn dendrite suppression, was also tested. From them, bismuth oxide (Bi₂O₃) was selected and added, together with calcium hydroxide (Ca(OH)₂), to the Zn electrode. A charging method, applying an intermittent anodic pulse, was found to be effective to reduce the Zn electrode shape change and prolong the cycle life of this cell. By using these materials and investigating a cell construction containing an electrolytic solution and hydrogen gas absorber, sizes AA, C, and D sealed NiZn cells were developed whose charging and discharging cycle life achieved over 500 cycles, for a size C cell.     

Electrical and magnetic properties of rare-earth sulfides, (Sm1−xGdx)3S4

Electrical and magnetic properties of mixed-valence rare-earth sulfides, (Sm_1?xGd_x)₃S₄, were investigated. The valence transition from trivalent to divalent samarium ions takes place gradually with increasing gadolinium concentration. In the range between x=0.80 and x=0.85, a drastic change from semiconducting to metallic conduction was observed. This phenomenon is explained by the valence change of the samarium ion in the solid solution. A mechanism of the conduction in the semiconducting sulfide is an electron hopping between Sm²⁺ and Sm³⁺ sites, and that in the metallic sulfide is a band conduction through conduction electrons. A maximum in the resistivity vs temperature curve for a metallic sample appeared near its Curie temperature. This behavior was found to result from the formation of magnetic polarons.     

Quantitative analysis of branching in poly(ortho ester) networks

A direct method to quantify the branching attributable to fully reacted hexane-1,2,6-triol (HT) in poly(ortho ester) networks is reported. The method was based on the presence of free hydroxyl groups on incompletely reacted HT in the poly(ortho ester) matrix that were “tagged” prior to matrix hydrolysis. HT molecules that were completely reacted, i.e., acting as cross-linker, within the polymer matrix would have no free hydroxyl groups available for “tagging” and posthydrolysis would be present as free HT. Experimentally, the matrix was swollen in p-dioxane, then phenyl isocyanate (PhCNO) was added to “tag” the hydroxyl groups in the presence of a stannous octoate catalyst. After removal of excess PhCNO, the matrix was hydrolyzed under mild acidic conditions. Any “untagged” HT was subsequently derivatized into trimethylsilyl ethers and analyzed by gas chromatography (GC). The level of branching determined by this direct chemical method correlated well with conventional swell ratio measurements. Furthermore, the extent of hydrolysis of the polymer backbone covalent bonds were also measured by this method since the resulting hydroxyl groups were “tagged” by PhCNO. All polyols were analyzed simultaneously by GC. Application of this method in characterization of the solid-state hydrolysis of a poly(ortho ester) network was demonstrated. The degradation profiles of the branch sites and other backbone ortho ester bonds showed that the hydrolysis was initially slow, becoming progressively rapid. © 1993 John Wiley & Sons, Inc.     

Finite element steady-state solutions of the traveling magnetic field problem

The paper is concerned with stability and accuracy of n-order finite element (FE) steady-state solutions of traveling magnetic field problem. It is found that the odd-order FE solutions (nis the odd number) are stable0 < sigma|u|h|nu < f(n) simeq 2.0 + 1.4(n - 1), and that the even-order FE solutions (nis the even number) are unconditionally stable. The consistent domain is also proposed, in which then-order FE solutions are stable and of 2n-order accuracy. Moreover, three-dimensional cases are dealt with, and the comparison with upwind methods is given. The merit and limits of the n-order FE method are finally cleared.