Bis-aminoquinolines as potential antimalarial agents and a novel fused ring system,pyrano[3,2-c:5,6-c′]diquinoline

3,3′(1,3-Ethyliminodimethylene)bis(4-hydroxy-6-methoxy-2-methyl)quinoline ( 2c ) and related compounds were synthesized. 3,3-Methylenebis(4-hydroxy-6-methoxy-2-methyl)quinoline ( 5 ) was prepared and upon treatment with phosphorus oxychloride gave 1,13-dimethyl-5,9-dimethoxy-14H-pyrano[3,2-c:5,6-c′]diquinoIine (6), a novel ring system.     

Electronic spectra, solvatochromic behavior and acid-base properties of some azo cinnoline compounds

The electronic spectra of three azo cinnoline derivatives have been studied in pure and mixed organic solvents of different characteristics as well as the effect of concentration of the compounds in the different solvents. The different bands observed have been assigned to the proper electronic transition. The longer wavelength band displayed by the para nitro cinnoline derivative in dimethylformamide (DMF) solution is assigned to an intermolecular CT transition. The solvated H-bonding complexes formed between DMF and the para nitro derivative were investigated. DeltaG and K(f) values of these complexes have been determined. The acidity constants of the para nitro compound were determined from the spectra in aquous-methanolic solution of varying pH values. The effect of temperature on the longer wavelength visible band of p-NO(2) has been investigated.     

γγ-Disubstituted Itaconic Acids. Part 1. The Stobbe condensation of 1-arylnaphthyl ketones with diethyl succinate

Arylnaphthyl ketones condense with diethyl succinate yielding the stereoisomeric half-esters 2a–2d which were subjected to a series of reactions leading to 1-phenylphenanthrene and 1,1′-binaphthyl derivatives. (E)-3-Ethoxycarbonyl-4-(4-methoxynaphth-1-yl)-4-arylbut-3-enoic acids ( 2b–d ) were converted finally into the corresponding naphtho[1,2-c]fluorenones ( 9 ). The structure of the products was established by IR. and UV. spectroscopy. The effect of substituents on the relative proportions of (E)- and (Z)-half-esters 2 was determined by chromatography and UV. spectroscopy.     

Effect of sulfur on the electrical conductivity of FEF-loaded SBR during swelling

Following a series of experiments on the effect of different factors of the electrical conductivity of carbon-black-loaded styrene butadiene rubber, an attempt was made to study the effect on electrical conduction of changing the sulfur content. It was found that an optimum sulfur content leads to a swelling-resistant composite with good electrical insulation. This was done for dry as well as wet specimens of rubber.     

Measurement of the proton total reaction cross section for 159Tb, 181Ta and 197Au between 20 and 48 MeV

Proton total reaction cross sections have been measured for the nuclei ¹⁵⁹Tb, ¹⁸¹Ta and ¹⁹⁷Au at seven proton energies between 20 and 48 MeV using an attenuation technique. The experimentally determined energy dependence of the total reaction cross sections is compared with results obtained for black nucleus and optical model calculations.     

Structure cristallographique et magnetique de Cr1−xTixN a basse temperature

Cr_1?xTi_xN solid solutions have at room temperature a crystallographic structure of NaCl type. The space group is Fm3m. The compounds with x ? 0.15 present at low temperature an antiferromagnetic order of the fourth kind and show an orthorhombic distorsion. The space group of the deformed phase is Pnmm. The magnetic moment measured by neutron diffraction decreases with increasing titanium concentration. The compounds with x ? 0.20 do not show any magnetic order and any crystallographic distortion at very low temperature.     

The role of the weakest-link mechanism in controlling the plasticity of micropillars

We present a computational study on the effects of sample size on the strength and plastic flow characteristics of micropillars under compression loading. We conduct three-dimensional simulations using the parametric dislocation dynamics coupled with the boundary element method. Two different loading techniques are performed. The plastic flow characteristics as well as the stress-strain behavior of simulated micropillars are shown to be in general agreement with experimental observations. The flow strength versus the diameter of the micropillar follows a power law with an exponent equal to -0.69. A stronger correlation is observed between the flow strength and the average length of activated dislocation sources. This relationship is again a power law, with an exponent -0.85. Simulation results with and without the activation of cross-slip are compared. Discontinuous hardening is observed when cross-slip is included. Experimentally observed size effects on plastic flow and work-hardening are consistent with a “weakest-link activation mechanism”.     

Tripartite Entanglements in Noninertial Frames

Entanglement degradation caused by the Unruh effect is discussed for the tripartite GHZ or W states constructed by modes of a non-interacting quantum field viewed by one inertial observer and two uniformly accelerated observers. For fermionic states, the Unruh effect even for infinite accelerations cannot completely remove the entanglement. However, for the bosonic states, the situation is different and the entanglement vanishes asymptotically. Also, the entanglement is studied for the bipartite subsystems. While for the GHZ states all the bipartite subsystems are identically disentangled, for the W states the bipartite subsystems are somewhat entangled, though, this entanglement can be removed for appropriately accelerated observers. Interestingly, logarithmic negativity as a measure for determining the entanglement of one part of the system relative to the other two parts, is not generally the same for different parts. This means that we encounter tripartite systems where each part is differently entangled to the other two parts.