Asset Pricing and Productivity Growth: The Role of Consumption Scenarios

The paper analyzes the performance of asset prices implied by an aggregate macroeconomic growth model under two different consumption hypotheses: overlapping generations of agents with two period lives versus the infinitely lived agent. The production side of the economy is described by a random growth model with a competitive labor market and an exogenously given random dividend payout ratio. For an isoelastic technology with multiplicative production shocks this implies a random dynamical system for the firm’s rate of profit with a unique asymptotically stable random fixed point for a large class of productivity growth and dividend payout ratio processes. Based on an extensive numerical study of stationary solutions we show that the two consumption scenarios imply a limited number of diverse effects regarding equity and bond returns and equity premia.     

High temperature catalytic combustion of methane and propane over hexaaluminate catalysts: NOx emission characteristics

Several hexaaluminate-related materials were prepared via hydrolysis of alkoxide and powder mixing method for high temperature combustion of CH₄ and C₃H₈, in order to investigate the effect of the concentration of the fuels, O₂ and H₂O on NO_x emission and combustion characteristics. Among the hexaaluminate catalysts, Sr_0.8La_0.2MnAl₁₁O₁₉₋ prepared by the alkoxide method exhibited the highest activity for methane combustion and low NO_x emission capability. NO_x emission at 1500 °C was increased linearly with O₂ concentration, whereas water vapor addition decreased NO_x emission in CH₄ combustion over the Sr_0.8La_0.2MnAl₁₁O₁₉₋ catalyst. In the catalytic combustion of C₃H₈ over the Sr_0.8La_0.2MnAl₁₁O₁₉₋ catalyst, the amount of NO_x emitted was raised in the temperature range between 1000 and 1500 °C when the C₃H₈ concentration increased from 1 to 2 vol.%. It was found that NO_x emission in this temperature range was reduced effectively by adding water vapor.     

Melting and glass transition of radiation-induced graft polyethylene

Melting and glass transition data are reported employing DSC for styrene-grafted high-density polyethylene obtained by γ radiation. Judging from the data of the melting point and the heat of fusion, the grafted polystyrene had no effect on the polyethylene crystallites, but the half-width of the thermogram was observed to increase slightly, showing an effect on the crystallite size distribution. As no effect was observed on the glass transition temperature by grafting, the amorphous region of the polyethylene apparently was not affected. It is suggested, therefore, that the free volume or segmental mobility will not be decreased by radiation-induced grafting. Very few but long grafted chains had negligible effect on the average polyethylene chain length available for segmental motion, and grafted polystyrene should be expected to differ little from the styrene homopolymer in thermal motions.     

High-strength–high-modulus polyimide fibers II. Spinning and properties of fibers

The polyimides based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) described in Part I of this series were dissolved in p-chlorophenol and spun into fibers using a coagulating bath of ethanol. The fibers as spun had in general low tenacities and low moduli, but a heat treatment at 300–500°C under tension produced a remarkable increase in strength and modulus, and fibers with a tensile strength of 26 g/den (3.1 GPa) and an initial modulus higher than 1,000 g/den (120 GPa) could be obtained. Thus, the annealed fibers of polyimides are comparable to aramid fibers in mechanical properties. To heating in air and in the saturated steam, the polyimide fibers showed higher resistance than the aramid fibers. The polyimide fibers surpassed the aramid fibers in resistance to acid treatment and ultraviolet (UV) irradiation, but were inferior in resistance to alkali treatment. The annealed fibers of polyimides displayed distinct X-ray diffraction patterns. The chain repeat distance of 20.5 Å determined on the fibers of polyimide prepared from BPDA and o-tolidine, and 20.6 Å determined on the fibers of polyimide derived from BPDA and 3,4′-diaminodiphenyl ether are reasonable when the dimensions of monomeric units and the shapes of the molecular chains are considered. The X-ray reflections of both polyimide fibers were indexed satisfactorily on the basis of postulated unit cells.     

Effects of 6-anilino-1,3,5-triazine-2,4-dithiol,zinc stearate,and barium stearate on the thermal stabilization of PVC

Individual action and synergistic effect in the combination of 6-anilino-1,3,5-triazine-2,4-dithiol (AF), zinc stearate, and barium stearate on the color stabilization of PVC were investigated. In this system, AF selectively reacts with allylic chlorine atoms in PVC. Consequently, unstable allylic chlorine units were converted to thermally stable allylic structures, thus retarding the development of polyene sequences. Zinc stearate accelerated the reaction of AF with allylic chlorine atoms in PVC, forming the zinc salts of AF (AFZ_nSt, St?C₁–H₃₅COO? ) by reacting with AF. Barium stearate reacted with ZnCl₂ which is formed in the above reaction to give St₂Zn and BaCl₂. Consequently, barium stearate led to the selective reaction of AF with allylic chlorine atoms in PVC and the remarkable retarding effect of discoloration of PVC.     

Voltammetric study of electrocatalysis for dioxygen reduction by trinuclear rutheniumammine complex confined in a polymer membrane

Electrocatalytic O₂ reduction was studied using a modified electrode coated with a Nafion membrane (Nf) dispersing a trinuclear ruthenium ammine complex ([(NH₃)₅Ru^IIIORu^IV(NH₃)₄ORu^III(NH₃)₅]Cl₆, Ru-red). When measuring cyclic voltammogram under O₂ atmosphere (at 0.5 mV s⁻¹), catalytic currents due to O₂ reduction were found to develop below −0.2 V (vs. Ag/AgCl). Since Ru-red undergoes irreversible decomposition into the mononuclear complexes via the reduced state (Ru^III-Ru^III-Ru^III) (∼−0.1 V), it is suggested that the electrocatalysis originates from the decomposed species (initial active species: Ru^II(NH₃)₅(OH₂) and Ru^II(NH₃)₄(OH₂)₂) rather than from the Ru-red. Although the present electrocatalyst was also applied to H₂O₂ reduction system, the catalytic activity was found to be poor from the voltammetric behavior. It appeared that the kinetics of the electrocatalysis is much faster in the O₂ reduction than in the H₂O₂ one. A selective and direct catalysis for O₂ reduction into H₂O was suggested from a ring-disk voltammogram to take place by an aggregate of the mononuclear ruthenium complexes in the polymer matrix. In addition, it was found that electrocatalytic O₂ reduction involves a slow kinetic process, so that factors affecting the overall kinetics were discussed in terms of the catalysis mechanism.     

Synthesis and application of fluorescein- and biotin-labeled molecular probes for the chemokine receptor CXCR4

The design, synthesis, and bioevaluation of fluorescence- and biotin-labeled CXCR4 antagonists are described. The modification of D-Lys8 at an epsilon-amino group in the peptide antagonist Ac-TZ14011 derived from polyphemusin II had no significant influence on the potent binding of the peptide to the CXCR4 receptor. The application of the labeled peptides in flow cytometry and confocal microscopy studies demonstrated the selectivity of their binding to the CXCR4 receptor, but not to CXCR7, which was recently reported to be another receptor for stromal cell-derived factor 1 (SDF-1)/CXCL12.     

Modification of bismaleimide resin by poly(propylene phthalate), poly(butylene phthalate) and related (co)polyesters

Aromatic polyesters were prepared and used to decrease the brittleness of the bismaleimide resin composed of 4,4′-bismaleimidediphenyl methane (BMI) and o,o′-diallyl bisphenol A (DBA) (Matrimid 5292 resin). The aromatic polyesters included poly(propylene phthalate) (PPP), poly(2,2-dimethylpropylene phthalate) (PDPP), poly(butylene phthalate) (PBP) and poly(butylene phthalate-co-butylene terephthalate) (50mol% terephthalate unit) (PBPT). The polyesters were effective modifiers for decreasing the brittleness of the bismaleimide resin. For example, inclusion of 20wt% PPP (MW 18700) led to 50% increase in the fracture toughness (K_IC) with retention of flexural properties and a slight loss of the glass transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Micro-structures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The thermal stability of the modified resins was slightly lower than that of the unmodified resin as determined by thermogravimetric analysis. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified bismaleimide resin system. © 1998 SCI.     

Very high temperature annealing effect on amorphous carbon films grown on refractory oxide substrates by pulsed laser deposition

We have carried out very high temperature heat treatment at 1400–2700 °C of about 10 nm-thick amorphous carbon thin films deposited on refractory substrates MgO, Al₂O₃, and yttria-stabilized zirconia (YSZ) using pulsed laser deposition techniques. After the annealing, a few nanometer scale sp² crystallization of the films and a large corrugation with a height of more than 1 μm were observed by Raman spectroscopy analysis and optical/atomic force microscopes, respectively. The corrugation is probably caused by the formation of gases at the film/substrate interface during the heat treatment.     

Synthesis of novel compounds with cation ordered fluorite and α-PbO2 related structures by oxidation of Sn2Nb2O7 pyrochlore

Sn(II)_1.2(Nb(V)_1.6Sn(IV)_0.4)O₆ pyrochlore precursor was oxidized at temperature of the range 573–973 K in 1% O₂/Ar and O₂ gases for various periods of time. Two kinds of novel metastable phases with a composition of Sn(IV)_0.6(Nb(V)_0.8Sn(IV)_0.2)O_3.6 could be synthesized. Further, the other novel metastable phase with the same composition was found as a phase contained. One of the metastable phases was the cubic κ-CeZrO₄ related-type possessing the fluorite-related structure, which was formed by the cation diffusionless insertion of the oxygen atom into original oxygen vacant site of the pyrochlore-type structure. Another was an orthorhombic α-PbO₂ related-type possessing a cation ordered arrangement unlike a well known NiWO₄ structure. The other was the rutile related-type possessing a cation ordered arrangement. Appearance of the two latter metastable phases could be attributed to the displacement of the oxygen stacking in the κ-CeZrO₄ related-type phase without cation redistributions. The appearance mechanisms were analogous to the well known transformations for AX₂ compounds among rutile-type, α-PbO₂-type, and fluorite-type phases under high pressure and its release. The dependence of the appearance of these novel metastable phases on oxygen partial pressure and temperature has been discussed in terms of the driving forces and energy barriers for reactions.