Bioavailability of essential trace elements in the presence of phytate, fiber and calcium

Summary Bioavailability and/or homeostasis of some essential trace elements such as zinc, iron, etc., in the presence of phytate, fiber and calcium are subject to alteration. These factors were measured in this study for Iranian diets in a frame of a Coordinated Research Project (CRP). However, the most prominent dietary factor in this regard is phytate. The phytate effect on zinc homeostasis is a chemical phenomenon dependent physiologically on pH in the gastrointestinal tract at or near the sites of absorption. Calcium is a synergistic coprecipitating factor in the complexation of zinc by phytate. Fiber has also a tendency to absorb insoluble compounds in gastrointestinal tract including zinc, iron and many other trace elements. One of the most known clinical observations regarding zinc deficiency was found in the rural area of the Fars province of Iran in the late 1950s at Shiraz University. However, the molar ratio of [phytate] : [zinc] and [calcium] [phytate] : [zinc] in Iranian Diets in a recent study are 7-17 and 150-800, respectively. The critical ratios of [phytate] : [zinc] of 10 or less will provide adequate zinc to sustain homeostasis.     

Novel toughened automotive clearcoats modified by a polyester‐amide hyperbranched polymer: structural and mechanical aspects

The present work attempts to study the mechanical properties and toughness behavior of a typical acrylic melamine clearcoat modified by a polyester‐amide hyperbranched polymer (HBP). Formulations were such that 0, 5, 10, 25 and 50% (molar percent) of total acrylic hydroxyl groups were stoichiometrically substituted by those of HBP. Bulk and surface of the clearcoats were studied by various mechanical techniques including hardness, tensile, dynamic mechanical thermal analysis (DMTA), nano‐indentation and scratch tests. In addition a scanning electron microscope (SEM) was utilized to observe the morphology of the fractured films. The bulk mechanical properties showed that a low loading (5 molar %) of HBP was sufficient to considerably increase the bulk hardness, cross‐linking density and toughness. DMTA and SEM results proved the occurrence of a single‐phase blend and that the shear deformation was the main toughening mechanism of HBP modified clearcoats. In general, it was revealed that the HBP not only could act as an excellent compatible toughening agent, but also maintained the clarity of the clearcoat and increased its scratch resistance. Copyright © 2013 John Wiley & Sons, Ltd.     

Efficient,Rapid, and Regioselective Bromination of Phenols and Anilines with N-Bromosaccharin Using Tungstophosphoric Acid as a Heterogeneous Recyclable Catalyst

A simple, efficient, and rapid method for high-yielding regioselective mono bromination of phenols and anilines has been achieved by treatment with N-bromasaccharin in the presence of a catalytic amount of tungstophosphoric acid.     

Synthesis and antibacterial activity of ethyl 2-amino-6-methyl-5-oxo- 4-aryl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate

The three-component reaction of 4-hydroxy-1-methyl-2(1H)-quinolinone, aromatic aldehydes and ethyl cyanoacetate was carried out in the presence of a catalytic amount of 4-dimethyl aminopyridine(DMAP) in aqueous ethanol. The reactions result in the formation of pyranoquinoline derivatives in excellent yields. Antibacterial activity has been evaluated against Gram positive and Gram negative bacteria for some of the synthesized compounds. The results indicated that these compounds are moderately effective against bacterial growth and their effectiveness is highest against Pseudomonas aeruginosa.     

One-pot synthesis of new hydantoin (thiohydantoin) derivatives and evaluation of their antibacterial and antioxidant activities

One-pot four-component reactions of phenacyl bromides, parabanic or thioparabanic acids, thiophenols, and triphenylphosphine in the presence of triethylamine afforded new derivatives of hydantoin or thiohydantoin in good to high yields (65%-90%). Their antibacterial activities were evaluated against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Among the synthesized compounds, the obtained products from 2-hydroxythiophenol exhibited higher antibacterial activity than those obtained from 2-aminothiophenol. Compound 9l including N,N′^′-diphenyl thiohydantoin moiety showed the highest antibacterial activity (26.0 ± 01.4) against B subtilis, in comparison with other synthesized samples. The antioxidant activities of the synthesized hydantoins and thiohydantoins were investigated by DPPH radical-scavenging based on Blois method. The results showed that all the compounds have high DPPH inhibition potency (77.4%-83.9%) that it could be due to existence of heteroatoms with lone pair electrons and exchangeable protons on their NH₂ and OH groups.     

Electrostatic self-energy and Bekenstein entropy bound in the massive Schwinger model

We obtain the electrostatic energy of two opposite charges near the horizon of stationary black holes in the massive Schwinger model. Besides the confining aspects of the model, we discuss the Bekenstein entropy upper bound of a charged object using the generalized second law. We show that despite the massless case, in the massive Schwinger model the entropy of the black hole and consequently the Bekenstein bound are altered by the vacuum polarization.     

Using Taguchi experimental design to reveal the impact of parameters affecting the abrasion resistance of sol–gel based UV curable nanocomposite films on polycarbonate

This work aims at studying the abrasion resistance of differently formulated organic–inorganic hybrid coatings prepared by sol–gel method. The organic phase contained UV curable urethane acrylate oligomers and monomers having different functionalities. The inorganic phase was composed of tetraethyl orthosilicate (TEOS) and 3-methacryloxy propyltrimethoxy silane (MEMO). Through a Taguchi experimental design, the impact of influencing parameters such as molar ratio of precursors, hydrolysis ratio (R), post-curing temperature, post-curing time and weight percentage of inorganic to organic part were investigated. Very high transparency of hybrid coatings indicated that nano sized inorganic phase had formed. MEMO could facilitate the connection of two phases, preventing macro phase separation. However, high levels of MEMO lead to ‘defect structure’ in silica network as well as to decreased transparency and mechanical properties. The optimum condition in which highly transparent films with great abrasion resistance occurred was observed at equimolar ratio of water to alkoxide and TEOS: MEMO ratio being unity. Statistical analysis revealed that thermal post-curing was not significantly important.     

Electropolymerization of Thin Film Conducting Polymer and Its Application for Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid

In this paper electropolymerization of a thin film of para‐phenylenediamine (PPD) is studied at glassy carbon electrode (GCE) in sulfuric acid media by cyclic voltammetry. The results showed that this polymer was conducting and had a reproducible redox couple in the potential region from 0.0 to 0.4 V in phosphate buffer solution. This modified GCE (p‐PPD‐GCE) was applied for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) using differential pulse voltammetry (DPV). The p‐PPD‐GCE in 0.1 M phosphate buffer solution (pH 5.0) separated the DPV signals of AA, DA and UA with sufficient potential differences between AA–DA and DA–UA and also enhanced their oxidation peak currents. The oxidation currents were increased from 2.0 to 2000.0 µM for AA, 10.0 to 1250.0 µM for DA and 50.0 to 1600.0 µM for UA. The detection limits were evaluated as 0.4, 1.0 and 2.5 µM for AA, DA and UA, respectively (S/N=3).     

Rational invariants of certain orthogonal groups over finite fields of characteristic two

In this article we establish the conjecture of Huah Chu [8] on modular rational invariants of finite orthogonal groups over finite fields of characteristic two.

We prove that the invariant subfield of two cases non-singular, and singular quadratic space over a finite field of characteristic two is purely transcendental.