Matrix influence on the piezoelectric properties of piezoelectric ceramic/polymer composite exhibiting particle alignment

This study was addressed to the influence of an electric field strength applied at fabrication process and matrix properties, such as the dielectric constant and the Young's modulus, on “pseudo‐1‐3 piezoelectric ceramic/polymer composite” in order to further enhance the piezoelectricity of that. The pseudo‐1‐3 piezoelectric ceramic/polymer composite consists of linearly ordered piezoelectric ceramic particles in polymer material. Silicone gel, silicone rubber, urethane rubber, and poly‐methyl‐methacrylate, which exhibit different dielectric constants and Young's modulus, were used as matrices to evaluate the matrix influence. The piezoelectricity of the pseudo‐1‐3 piezoelectric ceramic/polymer composite was evaluated using the piezoelectric strain constant d₃₃. The d₃₃ is one of the indices of the piezoelectric properties for piezoelectric materials. As a result, it was confirmed that d₃₃ of the pseudo‐1‐3 piezoelectric ceramic/polymer composite increased with the increase of the electric filed strength applied at fabrication process, though, it reached a constant value at a certain strength value. Further it was confirmed that dielectric constant of the matrix had a small influence on d₃₃ of the pseudo‐1‐3 piezoelectric ceramic/polymer composite, however, in case of matrix of lower Young's modulus, d₃₃ was increase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41817.     

Unperturbed dimension of poly(4-acetoxystyrene) measured in good and theta solvents

In order to obtain the additional data concerning the unperturbed dimension of poly-4-substituted styrene, light scattering measurements are performed on the twenty-two fractions with molecular weight of (0.91–352)·10⁴ of poly(4-acetoxystyrene) in dioxan at 25°C, from which the molecular weight obtained was found easily to be evaluated with the gel permeation chromatography using THF. Phase separation experiments for this polymer indicate that the theta state is attained in isopropyl acetate at 19.7°C and butyl acetate at 26.8°C. By making viscosity measurements at that state, the value of K_Θ is directly evaluated as 5.4·10^?4 dl g^?1. The limiting viscosity number is also obtained in good solvents, THF and dioxan, at 25°C and constants of the Mark-Houwink-Sakurada equation in each solvent are determined. Further, approximately the same K_Θ as above is obtained from these data with the Stockmayer-Fixman plot. The calculated value of steric factor, 2.37, on this polymer may be plausible, compared with those of polyvinylaromatic derivatives.     

Simulation program for estimating statistical power of Cox's proportional hazards model assuming no specific distribution for the survival time

Small sample properties of the maximum partial likelihood estimates for Cox's proportional hazards model depend on the sample size, the true values of regression coefficients, covariate structure, censoring pattern and possibly baseline hazard functions. Therefore, it would be difficult to construct a formula or table to calculate the exact power of a statistical test for the treatment effect in any specific clinical trial. The simulation program, written in SAS/IML, described in this paper uses Monte-Carlo methods to provide estimates of the exact power for Cox's proportional hazards model. For illustrative purposes, the program was applied to real data obtained from a clinical trial performed in Japan. Since the program does not assume any specific function for the baseline hazard, it is, in principle, applicable to any censored survival data as long as they follow Cox's proportional hazards model.     

Extensions of polyacrylic acid ammonium salts in the adsorption layer to fluidize alumina slurries

An average shell volume occupied in the adsorption layer on alumina by a polyacrylic acid ammonium salts molecule (PAA) defined as the average area occupied by an adsorbed PAA on alumina multiplied by the average thickness of the water layer at the limit of thickening, has been calculated from the adsorbed amount of PAA and from the flow points of alumina in the presence of PAA of different molecular weights. A steric effect of the PAA dispersant on the dispersion of alumina resulted in a flow with no yield stress. This was due to the change of the extension of PAA in the adsorption shell from a sphere to an ellipsoid with a long axis which exceeded the effective distance that the van der Waals attraction force reaches at a molecular weight for the PAA of between 10 000–20 000.     

Dissolution of phase-separated domains after a jump to a temperature in the single-phase region

Phase-separated domains prepared in the two-phase region were dissolved at a temperature in the single-phase region, and their dissolution dynamics was studied by using the time-resolved light scattering (TRLS) technique and a scanning electron microscope (SEM). The time t_ps of preparation of domains was chosen to be long enough for phase separation to proceed into the late stage. The scattered light intensity at small wavenumbers increased before it attenuated. As t_ps increased, the increase at smaller wavenumbers became more significant and the peak intensity decreased only slightly with dissolution time. The characteristic wavenumber q_m evaluated from TRLS and SEM followed the power-law relation q_mt^−0.3.     

The effects of 18 alpha,beta-glycyrrhetinic acid on the hormonal induction of tyrosine aminotransferase in rat primary cultured hepatocytes

Complementary medicine (CM) is popular with patients but physicians do not feel at ease with this situation and some fear that the patient might be the loser. Their fear is based on the perception that some CM practitioners have dubious qualifications and competence and that too little is known about the efficacy and safety of many complementary therapies. It follows that, in the interest of the patient and all other parties involved, we urgently need more and better research to fill the void. Integration of complementary medicine into mainstream care requires a minimum of essential evidence. As in all areas of medicine, there can be no short cut to rigorous research.     

A flexible random allocation program for multi-institutional clinical trials

This paper describes a flexible random allocation program that assigns treatments to patients according to their prognostic factors in multi-institutional clinical trials. The source lists are available in the appendix of this paper. This program is based on Pocock and Simon's minimization method and Zelen's method for institution balancing. The numbers of institutions, treatments, and prognostic factors can be set arbitrarily. The maximum number of institutions, treatments, or prognostic factors that can be accommodated by the program is limited only by the size of the main memory. For example, an IBM-PC with a 640KB main memory can run a program of 1500 institutions, 4 treatments and 20 prognostic factors.     

Stability of protective oxide films in waste incineration environment—solubility measurement of oxides in molten chlorides

Solubility measurements of several oxides in molten NaCl-KCl and NaCl-KCl-Na₂SO₄-K₂SO₄ were conducted in three different levels of basicity. The dissolution behavior of the oxides showed almost the same tendency as that shown by the dissolution behavior of the oxides in molten Na₂SO₄ in literature. In a waste incineration environment, a protective Cr₂O₃ film easily dissolves in molten chlorides as CrO₄²⁻ because pO²⁻ of the molten chlorides tends to have a small value due to the effect of water vapor contained in the combustion gas. From the result of the solubility measurement, the addition of molybdenum and/or silicon was expected to improve the corrosion resistance of alloys. Laboratory corrosion tests confirmed this expectation. However, the scale analysis suggested that the effect of molybdenum could not be explained completely by only the mechanism derived from the result of the solubility measurement.     

Preparation of poly(p-phenylene terephthalamide)/poly(vinyl chloride) molecular composite and its thermal and mechanical properties

Poly(p-phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution-blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between C? Cl of PVC and N? H of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi-3-dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA.     

Interactions oftrans-cinnamic acid,its related phenolic allelochemicals,and abscisic acid in seedling growth and seed germination of lettuce

Phenolic compounds have been identified as the most common allelochemicals produced by higher plants. Inhibitions of cinnamic acid, its related phenolic derivatives, and abscisic acid (ABA) on seedling growth and seed germination of lettuce were studied.trans-Cinnamic acid, ando-,m-, andp-coumaric acids inhibited the growth of etiolated seedlings of lettuce at concentrations higher than 10^–4 M and seed germination above 10^–3 M. Coumarin inhibited seedling growth and seed germination at 10^–5 M or above. Chlorogenic acid inhibited seedling growth above 10^–4 M, but did not inhibit seed germination at 10^–5–5×10^–3 M. Low concentrations (below 10^–3 M) of caffeic and ferulic acids promoted the elongation of hypocotyls, but higher concentrations (over 10^–3 M) inhibited seedling growth and seed germination. These phenolic compounds and abscisic acid had additive inhibitory effects both on seedling growth and seed germination. The inhibition on lettuce was reversed by caffeic and ferulic acids at concentrations lower than 10^–3 M except for the inhibition of germination by coumarin. These results suggest that in naturetrans-cinnamic acid,o-, m-, p-coumaric acids, coumarin, and chlorogenic acid inhibit plant growth regardless of their concentration. However, caffeic and ferulic acids can either promote or inhibit plant growth according to their concentration.