Preparation and photocatalytic activity of porous spherical TiO2 particles comprised of H3PW12O40 in hydrophobic nanopores

Porous TiO₂ sphere particles were prepared by impregnating titanium (IV) oxysulfate solutions into organic monolith particles, with subsequent calcination in air. The powder possessed pores of meso-order. Its crystalline phase was anatase. Then, 12 Tungsto(VI) phosphoric acid (PW₁₂) was present in the mesopores. The entire surface was modified to be hydrophobic by octadecylphosphonic acid (ODP). Subsequent UV illumination in water removed the PW₁₂ and ODP adsorbed onto the outer sphere surface. The obtained spherical TiO₂ particles with hydrophobic acidic nanopores exhibited high photocatalytic performance against the removal of 1,4-dioxane in water. Detailed analysis revealed that this material removed both 1,4-dioxane and ethylene glycol diformate (EGDF), the main intermediate of the photocatalysis of 1,4-dioxane. Results suggest that hydrophobic acidic nanopores enhance adsorption of EGDF in water and play an important role in the overall photocatalytic performance of this system.     

Viscoelastic and fragmentation characters of model bolus from polysaccharide gels after instrumental mastication

Model bolus from polysaccharide gels was investigated by the stress-relaxation tests and particulate size analyses. Using two gelling agents, gellan gum and a composite of gellan/psyllium seed gums, gels with different physical properties (i.e., elastic gellan single gels and plastic composite gels) and gel hardness were prepared. Gels were masticated instrumentally in the presence or absence of artificial saliva to prepare model bolus. Data from the stress-relaxation tests analyzed by 5-element mechanical model showed that difference between two Maxwell-bodies in the elasticity for the composite gels was generally smaller than that for gellan single gels when compared at equivalent gel hardness and was less influenced by the addition level of saliva. For each gel sample, cumulative particulate size distribution of model bolus was reduced logarithmically with a normal curve regardless of the addition level of saliva. Mean particulate size of model bolus from the composite gels was generally larger than that for gellan single gels when compared at equivalent gel hardness and was less influenced by the addition level of saliva. Based on the particulate size distribution of model bolus, coefficients of skewness and kurtosis calculated for the composite gels tended to be larger than those for gellan single gels when compared at equivalent gel hardness. Results indicated higher structural homogeneity of model bolus from the composite gels, which is related to higher miscibility with saliva. Structural homogeneity should be the key for texture design of nursing-care foods, particularly for dysphagia.     

Characteristics of SiH4/H2 VHF plasma produced by short gap discharge

A SiH₄/H₂ VHF plasma was produced with the multi rod electrode and the fundamental plasma parameters were examined as a function of pressure and power, where the frequency of the power source was 60 MHz. It was found that the ion saturation current takes a peak at a certain power as well as pressure. These results were discussed from the point of view of electron trapping effect in VHF electric fields. In addition, anomalous reduction of the sheath potential was observed.     

Hydroxyapatite-induced alkaline phosphatase activity of human pulp fibroblasts

Hydroxyapatite is widely used clinically in the field of dentistry, however, the modulating action of hydroxyapatite with respect to the cells has not been investigated. In this study, it is described that one of the cytokines released by fibroblasts can cause increasing alkaline phosphatase (ALPase) activity of fibroblastsin vitro. Human pulp fibroblasts (HPFs) were cultured with hydroxyapatite (30–480 µg cm^–2) in serum-supplemented medium for 6 to 96 h, then the serum-free conditioned medium was obtained and added to sub-cnfluent HPF cultures. Significantly enhanced ALPase activity was detected when HPFs were incubated with the conditioned medium. This HPF-derived activity which induces increasing ALPase activity appeared in the conditioned medium with a 12h culture period, and the appearance of this mediator was completely inhibited in the presence of cycloheximide. Enhanced ALPase activity is detected in lesions in which calcification is occurring. The results of this experiment suggest that HPFs in contact with hydroxyapatite serve as a mediator in cell-to-cell interaction, and are related to the functional differentiation of cells for tissue repair including pulpal calcification.     

An MD simulation to form an NV-N center using N2 implantation into diamond

We have examined the dissociation process of a low-energy molecular beam making use of an empirical molecular dynamic simulation. The main concern was to explain why two (nitrogen molecule N₂) beams with different energy (sub-keV and keV) give a similar intrapair distance R_N-N in diamond. It was due to the peculiar dependence of the lateral range straggling on the incident energy across a few keV. When a sub-keV (N₂) beam was implanted into a diamond, the dissociation elapsed a long time until it was settled in several hundreds fs because of multiple collisions. The range distribution caused by multiple collisions is almost isotropic whereas it becomes anisotropic when used a (N₂) beam with the higher energy than that. From the viewpoint of computation, a few keV is a critical energy to choose an algorithm MD or MC with binary collision approximation. For the case of sub-keV N₂ beam, MD is indispensable. This proved the reason of the apparent contradiction. Much later than the collision stage, a definite change further occurred in the long-range-order of the crystal at around 2 ps in diamond. It seems a phonon-assisted phenomenon would start then and might affect on the further events to be occurred later than 20 ps.     

Swallowing profiles of food polysaccharide gels in relation to bolus rheology

Swallowing profiles of food polysaccharide gels were investigated in relation to bolus rheology. Polysaccharide gel from either gellan gum or a mixture of gellan gum and psyllium seed gum was used as a model food. Acoustic analysis and sensory evaluation were carried out to investigate the swallowing profiles using the same human subjects. Model bolus was prepared through instrumental mastication using a mechanical simulator to mimic the action of the human jaw in the presence or absence of artificial saliva and was subjected to dynamic viscoelasticity measurements to investigate the rheological properties. Bolus from the binary gel was shorter in time required to transfer through the pharyngeal phase due to mass flow and was scored higher in sensory perceived cohesiveness (bolus forming) than that from gellan gum gel. Model bolus from the binary gel showed a rheologically weak gel (or structured fluid) behavior and was higher in structural homogeneity than that from gellan gum gel. Also, dynamic viscoelasticity parameters of the binary gel were less dependent on the addition level of saliva. Results indicate that the viscoelasticity balance is a key for texture design of dysphagia foods in relation to the saliva miscibility.     

On phase relaxation processes

Time-evolutions of two-level and multi-level systems in phase relaxation processes are investigated in a systematic way. A general form of the decoherence function which determines phase relaxation of a quantum state is obtained by making use of a microscopic interaction Hamiltonian between the relevant system and reservoir. Furthermore the loss of the phase coherence is described in terms of the Pegg–Barnett phase operator. The decoherence function is explicitly calculated for the stochastic dephasing, the boson detector model and the Coleman–Hepp model.     

Plasma HDL Reduces Nonesterified Fatty Acid Hydroperoxides Originating from Oxidized LDL: a Mechanism for Its Antioxidant Ability

The antioxidant property of plasma high-density lipoprotein (HDL) is thought to be involved in potential anti-atherogenic effects but the exact mechanism is not known. We aimed to reveal the contribution of HDL on the elimination of lipid hydroperoxides (LOOH) derived from oxidized low-density lipoprotein (LDL). Oxidized LDL prepared by copper ion-induced oxidation contained nonesterified fatty acid hydroperoxides (FFA-OOH) and lysophosphatidylcholine (lysoPtdCho), in addition to cholesteryl ester hydroperoxides (CE-OOH) and phosphatidylcholine hydroperoxides (PtdCho-OOH). A platelet-activating factor-acetylhydrolase (PAF-AH) inhibitor suppressed formation of FFA-OOH and lysoPtdCho in oxidized LDL. Among LOOH species, FFA-OOH was preferentially reduced by incubating oxidized LDL with HDL. HDL exhibited selective FFA-OOH reducing ability if it was mixed with a liposomal solution containing FFA-OOH, CE-OOH and PtdCho-OOH. Two-electron reduction of the hydroperoxy group to the hydroxy group was confirmed by the formation of 13-hydroxyoctadecadienoic acid from 13-hydroperoxyoctadecadienoic acid in HPLC analyses. This reducing effect was also found in apolipoprotein A-1 (apoA-1). FFA-OOH released from PtdCho-OOH due to PAF-AH activity in oxidized LDL undergo two-electron reduction by the reducing ability of apoA1 in HDL. This preferential reduction of FFA-OOH may participate in the mechanism of the antioxidant property of HDL.     

Effects of silicate and phosphate ions on the formation of ferric oxide hydroxide particles

The effects of silicate and phosphate ions on the formation of α- and β-FeOOH particles were studied. The formation and crystallization of α-FeOOH particles were inhibited by both the anions, and their particle size decreased with increasing concentration of the anions added. This inhibition was caused not only by complexing with ferric ions but also by adsorption on the particle surface. For α-FeOOH the amorphous particles were formed at a higher concentration of these anions. On the other hand, in the case of β-FeOOH the effects of both the anions were little, especially for silicate ions. This difference between α- and β-FeOOH particles could be explained by the difference between their preparation pH. The α-FeOOH particles prepared in the presence of these anions showed a microporosity.     

Effect of protic solvents on the polarographic reduction of the alkali metal ions in hexamethylphosphoric triamide

Sodium and lithium ions are not reduced at the dropping mercury electrode in hexamethylphosphoric triamide containing 0.05 mol dm^?3 tetraethylammonium perchlorate while rubidium and caesium ions show diffusion controlled, l-electron reduction waves. The reduction of potassium ion is partially kinetic. When increasing amount of water is added to the solution, reduction waves of sodium and lithium begin to appear, and the kinetic contribution of potassium wave gradually disappears to give a diffusion controlled wave. The diffusion controlled waves of rubidium and caesium ions are essentially unaffected. The addition of methanol, ethanol, l-buthanol and dimethyl sulfoxide also has similar enhancing effects, which is attributed to the acceleration of the desolvation process by protons. These effects of protic solvent are apparently similar to that of the cation size of the supporting electrolytes, but of different origin, as indicated by the different behavior of the electrocapillary curves.