Effects of MoOx modification on photocatalytic activity of hydroxyapatite and Ti-doped hydroxyapatite

Titanium-doped hydroxyapatite (Ti-HAp, (Ca_10-2x, Ti_x, □_x) (PO₄)₆(OH)₂, □: defect in Ca site) and hydroxyapatite (HAp, Ca₁₀(PO₄)₆(OH)₂) powders were modified with an ethanol solution of molybdenyl acetylacetonate (MoO₂(C₅H₈O₂)₂) using chemisorption calcination cycle (CCC) technique, which provides metal oxide clusters. Their photocatalytic activity under UV illumination was evaluated by the decomposition of gaseous 2-propanol. The photocatalytic activity of the Mo-modified Ti-HAp samples increased concomitantly with increasing Mo concentration up to 0.72% against P. The highest photocatalytic activity of Mo-modified Ti-HAp was about 13 times higher than that of Ti-HAp. The signal appearance of Mo(V) in electron spin resonance spectra and the decrease of photoluminescence intensity suggest electron transfer from the Ti-hybridized band to the MoO_x cluster, which suppresses recombination of the photoinduced electron and hole pairs. The photocatalytic activity of Mo-modified HAp samples was attributed to HOMO–LUMO excitation of MoO_x cluster.     

Nanopatterning of silicon with use of self-organized porous alumina and colloidal crystals as mask

Nanopatterning processes based on a localized anodization of Si and the subsequent chemical etching of SiO₂ were developed to fabricate a dot array and a hole array on an Si surface using self-organized anodic porous alumina as a mask. Through the porous alumina mask, regularly arranged metal nanopatterns on the Si surface were fabricated by the electroless deposition of Cu nanodots in a CuSO₄/hydrofluoric acid (HF) solution. The periodicity of the Cu dot arrays was determined using the pore interval of the upper anodic alumina. Using self-assembled nanospheres as a mask for an electroless plating of metals such as Cu and Ag on the Si substrate, the patterning of an ordered honeycomb structure and a hexagonally arranged convex array of metals on Si was also developed by the combination of colloidal crystal patterning and wet chemical etching. The proposed patterning processes of the Si surface have potential technological applications in fields that need textured surfaces of controlled nanoscale periodicity and morphology owing to their relative simplicity and low cost.     

Effects of starch on nitrous acid-induced oxidation of kaempferol and inhibition of α-amylase-catalysed digestion of starch by kaempferol under conditions simulating the stomach and the intestine

Kaempferol glycosides can be hydrolyzed to their aglycone kaempferol during cooking under acidic conditions and in the oral cavity and the intestine by glycosidases. Kaempferol was oxidised by nitrite under acidic conditions (pH 2.0) to produce nitric oxide (NO), and the nitrite-induced oxidation of kaempferol was enhanced and inhibited by 10 and 100 mg of starch ml⁻¹, respectively. The opposite effects of starch were discussed by considering the binding of kaempferol to starch and starch-dependent inhibition of the accessibility of nitrous acid to kaempferol. Kaempferol inhibited α-amylase-catalysed starch digestion by forming starch/kaempferol complexes, and the inhibitory effects increased in the order of amylopectin < soluble starch < amylose. The different effects of kaempferol were discussed to be due to the difference in binding sites of kaempferol between amylose and amylopectin. From the present study, dual-function of kaempferol became apparent in the digestive tract.     

Dynamic adaptation to history of trial difficulty explains the effect of congruency proportion on masked priming.

In reaction time research, there has been an increasing appreciation that response-initiation processes are sensitive to recent experience and, in particular, the difficulty of previous trials. From this perspective, the authors propose an explanation for a perplexing property of masked priming: Although primes are not consciously identified, facilitation of target processing by a related prime is magnified in a block containing a high proportion of related primes and a low proportion of unrelated primes relative to a block containing the opposite mix (Bodner & Masson, 2001). In the present study, this phenomenon is explored with a parity (even/odd) decision task in which a prime (e.g., 2) precedes a target that can be either congruent (e.g., 4) or incongruent (e.g., 3). It is shown that the effect of congruence proportion with masked primes cannot be explained in terms of the blockwise prime–target contingency. Specifically, with masked primes, there is no congruency disadvantage in a block containing a high proportion of incongruent primes, but there is a congruency advantage when the block contains an equal proportion of congruent and incongruent primes. In qualitative contrast, visible primes are sensitive to the blockwise prime–target contingency. The authors explain the relatedness proportion effect found with masked primes in terms of a model according to which response-initiation processes adapt to the statistical structure of the environment, specifically the difficulty of recent trials. This account is supported with an analysis at the level of individual trials using the linear mixed effects model. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Flavin-Dependent Monooxygenases NotI and NotI′ Mediate Spiro-Oxindole Formation in Biosynthesis of the Notoamides

The fungal indole alkaloids are a unique class of complex molecules that have a characteristic bicyclo[2.2.2]diazaoctane ring and frequently contain a spiro-oxindole moiety. While various strains produce these compounds, an intriguing case involves the formation of individual antipodes by two unique species of fungi in the generation of the potent anticancer agents (+)- and (−)-notoamide A. NotI and NotI′ have been characterized as flavin-dependent monooxygenases that catalyze epoxidation and semi-pinacol rearrangement to form the spiro-oxindole center within these molecules. This work elucidates a key step in the biosynthesis of the notoamides and provides an evolutionary hypothesis regarding a common ancestor for production of enantiopure notoamides.     

Xylitol Affects the Intestinal Microbiota and Metabolism of Daidzein in Adult Male Mice

This study examined the effects of xylitol on mouse intestinal microbiota and urinary isoflavonoids. Xylitol is classified as a sugar alcohol and used as a food additive. The intestinal microbiota seems to play an important role in isoflavone metabolism. Xylitol feeding appears to affect the gut microbiota. We hypothesized that dietary xylitol changes intestinal microbiota and, therefore, the metabolism of isoflavonoids in mice. Male mice were randomly divided into two groups: those fed a 0.05% daidzein with 5% xylitol diet (XD group) and those fed a 0.05% daidzein-containing control diet (CD group) for 28 days. Plasma total cholesterol concentrations were significantly lower in the XD group than in the CD group (p < 0.05). Urinary amounts of equol were significantly higher in the XD group than in the CD group (p < 0.05). The fecal lipid contents (% dry weight) were significantly greater in the XD group than in the CD group (p < 0.01). The cecal microbiota differed between the two dietary groups. The occupation ratios of Bacteroides were significantly greater in the CD than in the XD group (p < 0.05). This study suggests that xylitol has the potential to affect the metabolism of daidzein by altering the metabolic activity of the intestinal microbiota and/or gut environment. Given that equol affects bone health, dietary xylitol plus isoflavonoids may exert a favorable effect on bone health.     

Quadrature operators with arbitrary phase and applications to phase-space distribution and quantum communication

Quadrature operators with arbitrary phase are studied from a point of view of the phase-space representation of quantum states, and the results are applied to simultaneous measurement and quantum communication. The Wigner function of arbitrary phase quadrature variables is introduced, which is a generalization of the usual Wigner function of position and momentum. The Kirkwood distribution is also extended for arbitrary phase quadrature variables. The simultaneous measurement of two quadrature operators is investigated using a beam splitter model and a generalized version of the Arthurs-Kelley model. The quantum teleportation of continuous variables is considered in terms of arbitrary phase quadrature variables. A general formula is derived that provides the quantum teleportation channel. The fidelity of the quantum teleportation with an uncontrollable phase is calculated for a coherent state. Furthermore, the mutual information of the quantum dense coding of continuous variables is obtained when classical information is encoded on arbitrary phase quadrature variables. The result is compared with that of the communication system, where information is transmitted using coherent and squeezed states.     

Micromorphological effect of calcium phosphate coating on compatibility of magnesium alloy with osteoblast

Abstract

Octacalcium phosphate (OCP) and hydroxyapatite (HAp) coatings were developed to control the degradation speed and to improve the biocompatibility of biodegradable magnesium alloys. Osteoblast MG-63 was cultured directly on OCP- and HAp-coated Mg-3Al-1Zn (wt%, AZ31) alloy (OCP- and HAp-AZ31) to evaluate cell compatibility. Cell proliferation was remarkably improved with OCP and HAp coatings which reduced the corrosion and prevented the H₂O₂ generation on Mg alloy substrate. OCP-AZ31 showed sparse distribution of living cell colonies and dead cells. HAp-AZ31 showed dense and homogeneous distribution of living cells, with dead cells localized over and around corrosion pits, some of which were formed underneath the coating. These results demonstrated that cells were dead due to changes in the local environment, and it is necessary to evaluate the local biocompatibility of magnesium alloys. Cell density on HAp-AZ31 was higher than that on OCP-AZ31 although there was not a significant difference in the amount of Mg ions released in medium between OCP- and HAp-AZ31. The outer layer of OCP and HAp coatings consisted of plate-like crystal with a thickness of around 0.1 μm and rod-like crystals with a diameter of around 0.1 μm, respectively, which grew from a continuous inner layer. Osteoblasts formed focal contacts on the tips of plate-like OCP and rod-like HAp crystals, with heights of 2–5 μm. The spacing between OCP tips of 0.8–1.1 μm was wider than that between HAp tips of 0.2–0.3 μm. These results demonstrated that cell proliferation depended on the micromorphology of the coatings which governed spacing of focal contacts. Consequently, HAp coating is suitable for improving cell compatibility and bone-forming ability of the Mg alloy.