Radiation vulcanization of NR/SBR composite enhanced with different polyfunctional monomers

The effect of different polyfunctional monomers (PFMs) as enhancing agents on the properties of natural rubber/styrene-butadiene rubber blend reinforced with 40 (phr) part per hundred part of rubber, by weight of HAF carbon black and vulcanized with gamma irradiation was investigated. The coagents N,N’ methylene diacrylamide (MDA), trimethylol propane-trimethacrylate (TMPTMA) and trimethylol-methane tetraacrylate (TMMTA) were used at a constant content of 5 phr. The physico-chemical properties such as tensile strength, tensile modulus at 100 % elongation, elongation at break, gel fraction and swelling number were studied. The results indicated that the properties are greatly improved by PFMs at lower doses. TMMTA as coagent is more effective than TMPTMA and MDA.     

Antibacterial and Antifungal Activities—Surface Active Properties Relation of Novel Dischiff Base Cationic Gemini Amphiphiles Bearing Homogeneous Hydrophobes

A novel series of cationic Gemini amphiphiles containing Dischiff base species were synthesized and their chemical structures were determined using different analytical tools. Their surface properties were determined using surface tension measurements. The adsorption and micellization thermodynamic parameters were calculated using Gibb's equations at 25°C. The surface parameters were also determined including critical micelle concentration, effectiveness, efficiency, maximum surface excess, minimum surface area, interfacial tension, and emulsification power. The synthesized cationic Gemini surfactants were evaluated as bactericides for gram negative and gram positive bacteria and also against sulfur reducing bacteria (SRB). The results of the cytotoxicity of the synthesized compounds against the targeted bacterial strains were promising and completely dependent on the surface activity of these compounds.     

Synthesis and antidiabetic activity of novel triazole derivatives containing amino acids

New series of triazole derivatives coupled with amino acids 1a-h were obtained via multicomponent reaction of 2-hydroxy benzaldehyde or 2-hydroxy acetophenone with thiosemicarbazide and different amino acids. The obtained compounds were reacted with p-toluinesulfonyl chloride 2 to give the corresponding sulfonamides 3a-h . Compound 1b was allowed to react with different aromatic aldehydes or cyclic ketone under alkaline conditions to afford the expected imino compounds 4a-d and 6a-c , respectively. These compounds were allowed to react with ethyl glycolate to yield the expected thiazolidinone derivatives 5a-d or 7a-c , respectively. Structures of the newly synthesized compounds were found to be in accordance with their elemental analyses and spectral data. The obtained compounds exhibited very prominent in vitro and in vivo antihyperglycemic effect at a dose of 40 mg/kg body weight compared to the standard drug gliclazide and control. The antidiabetic effect was investigated using oral glucose tolerance test in normal and non-insulin-dependent diabetes mellitus (NIDDM) in STZ-rat model. Compounds 3a - h , 5b , 5c , 5d , 7a , 7b , and 7c showed significant activity in lowering blood glucose (more than 80%) compared to the NIDDM control.     

The pyridyl-tag strategy applied to the hydrocarbon/perfluorocarbon phase-switching of a porphyrin and a fullerene

A new hydrocarbon/perfluorocarbon phase-switching strategy based on coordination of pyridyl-tagged molecules to a highly fluorinated dicopper-carboxylate complex possessing two accessible axial coordination sites is described. When a chloroform solution of the tetrapyridyl-substituted porphyrin 3 (0.1 mM, 2 mL) is layered on a perfluorodecalin solution of 2 (3.25 mM, 1.5 mL), complete extraction of the porphyrin into the fluorous phase is observed after 30 min of stirring. Quantitative release of both the porphyrin and 2 is achieved simply by adding excess THF to the biphasic system, the THF acting as a pyridine competing ligand. The recovered perfluorocarbon solution containing 2 can be reused for another complexation with the same efficiency. The scope of this approach is emphasized by the phase-switching of a dipyridyl-substituted fullerene, another example of a molecule for which solubilization in perfluorocarbons is very challenging.     

A Dielectric Chirped Layered Mirror for Optical Telecommunication Wavelengths

We describe in this paper a design procedure for omnidirectional high reflectors with wide bandwidths for optical telecommunication bands. From the numerical results achieved by the transfer matrix method, it is found that a partial omnidirectional high-reflector covering the optical telecommunication wavelengths 1.3 and 1.55 μm is obtained for a partially deformed quarter-wave stack air/H(LH)¹⁵/glass by using the tellurium as a material of high refractive index (n _H = 4.6). The partially deformed stack is a periodic system deformed by a power law y = x ^1+k. Here y is the coordinates of the deformed object, x is the coordinates of the periodic stack and k is the coefficient defining the deformation degree. The study of this system leads to an omnidirectional high reflector band covering the optical telecommunication wavelengths 1.3 and 1.55 μm for k = 0.2.     

An asymptotic preserving scheme for the Kac model of the Boltzmann equation in the diffusion limit

In this article, we propose a numerical scheme to solve the Kac model of the Boltzmann equation for multiscale rarefied gas dynamics. Formally, this scheme is shown to be uniformly stable with respect to the Knudsen number, consistent with the fluid-diffusion limit for small Knudsen numbers, and with the Kac equation in the kinetic regime. Our approach is based on the micro–macro decomposition which leads to an equivalent formulation of the Kac model that couples a kinetic equation with macroscopic ones. This method is validated with various test cases and compared to other standard methods.     

A generalizaton of Hardy’s uncertainty principle on compact extensions of \mathbb R ^n

Let \(K\) be a compact subgroup of automorphisms of \(\mathbb R ^n\) . We prove in this paper a generalization of Hardy’s uncertainty principle on the semi-direct product \(K\ltimes \mathbb R ^n\) , and we solve the sharpness problem. As a consequence, a complete analogue of classical Hardy’s theorem is obtained. The representation theory and the Plancherel formula play an important role in the proofs.     

Photophysics and kinetics of naphthopyran derivatives,part 1: General analytical solutions for the kinetics of AB(k,ϕ) and ABC(k,ϕ) systems

A new formalism allowing solution of the differential equations for kinetic systems comprising three species (ABC) linked by first‐order thermal and/or photochemical reactions is proposed. The approach is developed specifically with photochromic materials in mind, but the formalism developed is shown to be applicable to a variety of kinetic systems irradiated with monochromatic light where the photokinetic factor ( F ) is constant. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 162–174, 2005     

On the route to mimic natural movements: synthesis and photophysical properties of a molecular arachnoid

The synthesis, photoswitchability and NIR emitting properties of a novel π-extended pyrene derivative, peripherally decorated with four azobenzenyl-ethynyl legs, are reported.