Regioselective Synthesis of Para‐Bromo Aromatic Compounds

Reaction of substituted benzene rings with N‐bromophthalimide, under neutral conditions, gave the corresponding bromo derivatives with a preference for the formation of the para bromo isomer over the ortho isomer. The simple work‐up procedure minimizes loss of product and the yields are good.     

Design of plasmonic nanoantennae for enhancing spontaneous emission

We apply two- and three-dimensional numerical calculations to study optical nanoantennae made of two coupled gold nanostructures, enclosing a single emitter in their gap. We show that, using structures manufacturable with today's nanotechnology, it is possible to increase the radiative decay rate by three orders of magnitude while keeping a quantum efficiency larger than 80% in the near-infrared regime. We examine the competition between the radiative and nonradiative processes in the presence of the antennae as a function of wavelength and antenna geometry. Our results hold great promise for improving the quantum efficiency of poor emitters such as silicon nanocrystals or carbon nanotubes.     

Novel nanocomposite membranes prepared with PVC/ABS and silica nanoparticles for C<Subscript>2</Subscript>H<Subscript>6</Subscript>/CH<Subscript>4</Subscript> separation

Composite membranes based on polyvinyl chloride and acrylonitrile butadiene styrene (ABS) copolymer have been prepared and then filled with 2–8 wt % of silica nanoparticles. Membranes were fabricated by solution casting method using dimethylacetamide. The performance of prepared membranes were studied for methane and ethane at the feed pressure of 1.0, 1.5, 2.0, and 3.0 bar at 35°C. By increasing the percentage of ABS, permeability of methane and ethane increased. In addition, by adding the silica nanoparticles in the membrane, permeability of gas increased in all cases. The highest gas pair selectivity for C₂H₆/CH₄ could be obtained from PVC/BS (20 wt %) which loaded with 8 wt % of silica nanoparticles. The results of this study suggest that high performance gas separation nanocomposite membranes can be attained by adopting a judicious combination of blending technique for polymeric membrane, optimized loading percentage, and feed operating conditions.     

Response surface optimization of heterogeneous Fenton-like degradation of sulfasalazine using Fe-impregnated clinoptilolite nanorods prepared by Ar-plasma

Research on Chemical Intermediates - Optimization of sulfasalazine degradation using the heterogeneous Fenton-like process in batch mode was investigated by response surface methodology. The...     

Maximum Order of Triangle‐Free Graphs with a Given Rank

The rank of a graph is defined to be the rank of its adjacency matrix. A graph is called reduced if it has no isolated vertices and no two vertices with the same set of neighbors. We determine the maximum order of reduced triangle‐free graphs with a given rank and characterize all such graphs achieving the maximum order.     

Synthesis, characterization, mechanochromism and photochromism of [Fe(dm4bt)3][FeCl4]2 and [Fe(dm4bt)3][FeBr4]2, along with the investigation of steric influence on spin state

The complexes [Fe(dm4bt)(3)][FeCl(4)](2) (1) and [Fe(dm4bt)(3)][FeBr(4)](2) (2) were prepared from the reaction of 2,2'-dimethyl-4,4'-bithiazole (dm4bt) with FeCl(3)·6H(2)O and FeBr(3), respectively, in methanol. Both complexes were characterized by IR, UV-Vis and (1)H NMR spectroscopy and their structures were studied by single-crystal diffraction. The methylated bithiazole led to high spin Fe(II) centers in the octahedral cation part of complexes 1 and 2 with Fe-N distance of 2.220 ?, in spite of the low spin octahedral Fe(II) complexes with unsubstituted bithiazole ligands. Crystal structure determination of 2 was performed at 90, 120 and 298 K. Temperature reduction to 90 K resulted in a decrease in the Fe-N bond length to 2.206 ? which is still in the range of high spin Fe(II). Complex 1 shows a reversible mechanochromic effect from the crystalline phase to powder form from red to yellow; it also displays reversible photochromism from yellow to green in solution under sunlight. The magnetic behaviour of the complexes was also studied at 2-300 K. The temperature dependence of χ(m)T curves for the two forms of 1, crystal and powder, demands some changes in their magnetic behavior, causing different colors i.e. red and yellow. At low temperatures, χ(m)T decreases where the decrease starts at around 65 K for compound 1, and at around 100 K for compound 2, due to different counterions. The two complexes exhibit antiferromagnetism at around 4 K.     

A channel differential EZW coding scheme for EEG data compression

In this paper, a method is proposed to compress multichannel electroencephalographic (EEG) signals in a scalable fashion. Correlation between EEG channels is exploited through clustering using a k-means method. Representative channels for each of the clusters are encoded individually while other channels are encoded differentially, i.e., with respect to their respective cluster representatives. The compression is performed using the embedded zero-tree wavelet encoding adapted to 1-D signals. Simulations show that the scalable features of the scheme lead to a flexible quality/rate tradeoff, without requiring detailed EEG signal modeling.     

Surface properties of nano-Al2O3 film and its application in the preparation of morphine electrochemical sensor

In this study, alumina nanoparticles and film were synthesized by sol–gel method and thermally grown. The chemical composition, morphology, and structural properties of the grain nanostructures of the nanoaggregate aluminum atoms on the silicon surface are characterized by X-ray diffraction, energy dispersive spectroscopy, and scanning electron microscopy techniques which show that the atomic ratio of Al and O elements is about 60:45 and the mass ratio is about 70:31. This point reveals that there is no intermediate layer between Al₂O₃ and the silicon substrate. In conclusion, this nanoparticle shows good electron conductivity at the surface of a carbon paste electrode that shows its ability in the preparation of a nanosensor in morphine analysis. The linear response range and detection limit were found to be 0.1–550 and 0.03 μmol L^?1, respectively. The proposed sensor was successfully applied for the determination of morphine in real samples such as human urine and drug.     

SpecSyn: an environment supporting the specify-explore-refineparadigm for hardware/software system design

System-level design issues are gaining increasing attention, as behavioral synthesis tools and methodologies mature. We present the SpecSyn system-level design environment, which supports the new specify-explore-refine (SER) design paradigm. This three-step approach to design includes precise specification of system functionality, rapid exploration of numerous system-level design options, and refinement of the specification into one reflecting the chosen option. A system-level design option consists of an allocation of system components, such as standard and custom processors, memories, and buses, and a partitioning of functionality among those components. After refinement, the functionality assigned to each component can then he synthesized to hardware or compiled to software. We describe the issues and approaches for each part of the SpecSyn environment. The new paradigm and environment are expected to lead to a more than ten times reduction in design time, and our experiments support this expectation