Conductivity of Tazheranite Ceramics Synthesized by Controlling Composition

Tazheranite ceramics with controlled compositions were synthesized by solid-phase reaction, and their conductivity was measured using the complex impedance method. The CaO content in tazheranite compositions showed the highest conductivity at around 15 mol%. In particular, Ca_0.81Ti_0.04O_y sintered bodies revealed the highest conductivity, and this value agreed very closely with that of 15 mol% CaO-stabilized ZrO₂.     

Liposome-assisted activity of superoxide dismutase under oxidative stress

A biological membrane is the front line of defense for cells against various environmental stresses such as heat and reactive oxygen species (ROS) and is expected to play an important role in the antioxidant system with antioxidant enzymes, similarly to its chaperone-like function in cooperation with heat shock proteins. The oxidative stress response of superoxide dismutase (SOD), which is known to catalyze the dismutation of O(2)(-) to H(2)O(2), was investigated in the presence of artificial membranes, liposomes, in order to obtain fundamental information on the biological ROS scavenging system. SOD lost its activity in the presence of H(2)O(2) and was found to have two loops including one which contains an alpha-helix which presents the substrate O(2)(-) to the activity center of SOD (Cu(II)). From circular dichroism analysis of SOD in the presence of H(2)O(2), the contents of the alpha-helix in SOD were found to decrease in correspondence with the inactivation and conformational change of SOD, suggesting that the conformation of the alpha-helix loops affects SOD activity. In the presence of liposomes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), SOD was not inactivated in the presence of H(2)O(2) although the contents of its alpha-helix structure were decreased. The oxidized SOD was found to interact with the liposome surface under oxidative stress using dielectric dispersion analysis. Based on these results, a possible mechanism of SOD protection against ROS on liposomes was presented.     

Theoretical calculation of fundamental uncertainty region based on the maximum and/or the minimum size in the preparation of standard reference particles for particle size measurement

In order to confirm the reliability of particle size measurement technique and to prepare standard reference particles for calibrating particle size measurement devices, experimental and theoretical studies have been conducted through particle size measurement of silica particles having a size range of 0.1–1 μm.A new theoretical equation to calculate fundamental uncertainty region in the case that the maximum and/or the minimum particle size is known, is derived based on a log-normal distribution truncated by the maximum and/or the minimum. Fundamental uncertainty regions calculated based on these truncated size distributions are compared with that calculated based on the perfect log-normal distribution. The relationship between the parameter u to determine the reliability of size distribution and the truncate-parameter g is obtained to get 95% reliability of the measurement. Value of the parameter u is fairly reduced as the truncate-parameter g becomes smaller.Numerical simulation of uncertainty region agreed with the results calculated by the new theoretical equation. Calculations on the silica particles having a size range of 0.1–1 μm have been conducted showing that the uncertainty region based on the known maximum size is slightly smaller compared to that given in the previous paper.     

Immobilization of microorganisms within porous polymeric capsules

Porous capsules suitable for immobilizing yeast and Escherichia coli were prepared by the phase separation of poly(m‐phenylene isophthalamide) solution. The microorganisms were coated with starch or dextrin, which was subsequently extracted after capsule formation but served both to position the microorganisms in the capsule pores and to form spaces around the microorganisms. Fermentation experiments were carried out with capsules immobilizing yeast. Yeasts could be cultivated in the capsules, and effective release of CO₂ produced by the fermentation was observed with capsules prepared using polyethylene glycol because of the porous structure at the capsule surfaces. Notably, yeasts could be cultivated at high density even after 1 year. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synergistic effects of organic and inorganic additives in preparation of composite poly(vinylidene fluoride) antifouling ultrafiltration membranes

Composite ultrafiltration membranes were successfully fabricated by blending a nonionic surfactant and inorganic nanoparticles via a nonsolvent-induced phase separation (NIPS) method. Brij35 was used as the nonionic surfactant and silica (SiO₂) nanoparticles from rice husk ash, a low cost and widely available material, were used as the inorganic nanoparticles. The synergetic effect of both additives was used to tailor the membrane structure and properties because the selected additives showed completely different or, in some cases, the opposite effect on the membrane properties and structure. The combined effects of Brij and SiO₂ resulted in a membrane with a noticeable improvement in membrane overall performance including pure water permeability, hydrophilicity, antifouling properties, long-term stability, tensile strength, on the cost of a slight decrease in membrane elongation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47737.     

Single step modification of micrometer-sized polystyrene particles by electromagnetic polyaniline and sorption of chromium(VI) metal ions from water

This article describes a single-step reproducible approach for the surface modification of micrometer-sized polystyrene (PS) core particles to prepare electromagnetic PS/polyaniline–Fe₃O₄ (PS/PANi–Fe₃O₄) composite particles. The electromagnetic PANi–Fe₃O₄ shell was formed by simultaneous seeded chemical oxidative polymerization of aniline and precipitation of Fe₃O₄ nanoparticles. The weight ratio of PS to aniline was optimized to produce core–shell structure. PS/PANi–Fe₃O₄ composite particles were used as adsorbent for the removal of Cr(VI) via anion-exchange mechanism. The composite particles possessed enough magnetic property for magnetic separation. The adsorption was highly pH dependent. Adsorption efficiency reached 100% at pH 2 in 120 min when 0.05 g of composite particles was mixed with 30 mL 5 mg L⁻¹ Cr(VI) solution. The adsorption isotherm fitted best with Freundlich model and maximum adsorption capacity approached 20.289 mg g⁻¹ at 323 K. The prepared composite was found to be an useful adsorbent for the removal of soluble Cr(VI) ions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47524.     

Preparation of porous membrane by combined use of thermally induced phase separation and immersion precipitation

By immersion in the cooled nonsolvent, PMMA porous membrane was prepared by the combined use of thermally induced phase separation (TIPS) and immersion precipitation. As nonsolvent, water with low mutual affinity with cyclohexanol (diluent) and methanol with high affinity were used. In the case of water, the porous structure was formed by TIPS immediately after the immersion. Near the top surface contacted with the nonsolvent, the thin skin layer was formed due to the outflow of the diluent. After the long immersion period, macrovoids were formed near the top surface due to the penetration of the nonsolvent. Thus, TIPS and the immersion precipitation occurred serially. On the contrary, TIPS and the immersion precipitation occurred simultaneously in the case of methanol because the inflow of methanol was fast. Therefore, the membrane obtained after the short immersion period had the larger pores near the top surface due to the nonsolvent induced phase separation and the smaller pores near the bottom surface due to TIPS. These two modes of the phase separations were confirmed by the changes in light transmittance through the polymer solutions.     

Identification of continuous-time systems with multiple unknown time delays by global nonlinear least-squares and instrumental variable methods

This paper considers the identification problem of multiple input single output (MISO) continuous-time systems with unknown time delays of the inputs, from sampled input-output data. An iterative global separable nonlinear least-squares (GSEPNLS) method which estimates the time delays and transfer function parameters separably is derived to significantly reduce the possibility of convergence to a local minimum, by using the stochastic global-optimization techniques. Furthermore, the GSEPNLS method is modified to a novel global separable nonlinear instrumental variable (GSEPNIV) method to remove the biases of the estimates in the presence of high measurement noise. Simulation results show that the proposed algorithms work quite well.     

The compaction of soot particles generated by spark discharge in the propene ozonolysis system

The compaction of soot aggregates generated by spark discharge is reported in the propene ozonolysis experiment. Since propene is not an organic aerosol precursor, the compaction cannot be explained by an earlier hypothesis attributing the compaction to the capillary forces of condensed organic matter in the small angle cavities of the aggregates [Saathoff, Naumann et al. (2003). Coating of soot and (NH₄)₂ SO₄ particles by ozonolysis products of alpha-pinene. Journal of Aerosol Science, 34, 1297–1321]. Several species among the gas-phase products from propene ozonolysis are proposed to contribute to the structural change of soot particles. As the compaction would directly change the morphology and the size distribution of soot particles, it is expected to induce important changes to the soot particles’ physical and chemical properties, which in turn would have significant atmospheric implications.     

Synthesis,physical properties,and crystallization of optically active poly(L‐phenyllactic acid) and poly(L‐phenyllactic acid‐co‐L‐lactic acid)

Optically active poly(L ‐phenyllactic acid) (Ph‐PLLA), poly(L ‐lactic acid) (PLLA), and poly(L ‐phenyllactic acid‐co‐L ‐lactic acid) with weight‐average molecular weight exceeding 6 × 10³ g mol^?1 were successfully synthesized by acid catalyzed direct polycondensation of L ‐phenyllactic acid and/or L ‐lactic acid in the presence of 2.5–10 wt % of p‐toluenesulfonic acid. Their physical properties and crystallization behavior were investigated by differential scanning calorimetry, thermogravimetry, and polarimetry. The absolute value of specific optical rotation ([α]) for Ph‐PLLA (?38 deg dm^?1 g^?1 cm³) was much lower than that of [α] for PLLA (?150 deg dm^?1 g^?1 cm³), suggesting that the helical nature was reduced by incorporation of bulky phenyl group. PLLA was crystallizable during solvent evaporation, heating from room temperature, and cooling from the melt. Incorporation of a very low content of bulky phenyllactyl units even at 4 mol % suppressed the crystallization of L ‐lactyl unit sequences during heating and cooling, though the copolymers were crystallizable for L ‐phenylactyl units up to 6 mol % during solvent evaporation. The activation energy of thermal degradation (ΔE_td) for Ph‐PLLA (200 kJ mol^?1) was higher than that for PLLA (158 kJ mol^?1). The ΔE_td for the copolymers increased with an increase in L ‐phenyllactyl unit content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008