Variation of long periodicity in blends of styrene butadiene,styrene copolymer/polyaniline using small angle X-ray scattering data

Small angle X-ray scattering data have been recorded for the blends of styrene butadiene, styrene copolymer/polyaniline using the beamline of the LNLS (Laboratorio Nacional de Luz sincroton-Campinas, Brazil). Employing one-dimensional Hosemann’s paracrystalline model, we have simulated the meridional reflections of these blends in order to compute the long periodicity and hence to find the variation with concentrations of the blends. Within the region of available experimental data we observe that there is a linear relationship between long periodicity and concentration of blends. These parameters are compared with physical measurements like tensile strength to find the structure-property relation in these blends.      

Total Synthesis of Myceliothermophins C,D, and E

The total synthesis of cytotoxic polyketides myceliothermophins E ( 1 ), C ( 2 ), and D ( 3 ) through a cascade‐based cyclization to form the trans‐fused decalin system is described. The convergent synthesis delivered all three natural products through late‐stage divergence and facilitated unambiguous C21 structural assignments for 2 and 3 through X‐ray crystallographic analysis, which revealed an interesting dimeric structure between its enantiomeric forms.     

Referential Opacity and Epistemic Logic

Referential opacity is the failure of substitutivity of identity (SI, for short) and in Quine’s view of existential generalization (EG, for short) as well. Quine thinks that its “solution” in epistemic and doxastic contexts, which relies on the notion of exportation, leads to undesirable results. But epistemic logicians such as Jaakko Hintikka and Wolfgang Lenzen provide another solution based on a different diagnosis: opacity is not, as in Quine’s view, due to the absence of reference, it is rather due to the plurality of references; therefore, one must stabilize the reference to restore SI and EG. However, Hintikka’s semantics remains classical in its treatment of existence, which makes EG non-applicable to possible objects, while in Lenzen’s system, EG is applicable by means of a particular quantifier. But this requires adding the predicate of existence to account for real objects. In this paper, I will show the advantages and disadvantages of both solutions and will end by providing an alternative approach to the problem of non-existent objects, which stays into the frame of possible worlds semantics, but introduces some more restrictions, eliminates the problematic predicate of existence, and applies a neutral quantifier to possible non-existent objects.     

5-Phenylpyridazinones-A serendipitous route from coumarins

A new route of the ring transformation has been discovered during the reaction of 4-bromomethylcoumarins with hydrazine hydrate leading to the formation of pharmacologically important pyridazinones in a single step with very high yields. These so obtained pyridazinones have the potential for further functional group interconversions.     

Strong persistence of an attractor and generalized partial synchronization in a coupled chaotic system

It is widely believed that when two discrete time chaotic systems are coupled together then there is a contraction in the phase space (where the essential dynamics takes place) when compared with the phase space in the uncoupled case. Contrary to such a popular belief, we produce a counter example--we consider two discrete time chaotic systems both with an identical attractor A, and show that the two systems could be nonlinearly coupled in a way such that the coupled system's attractor persists strongly, i.e., it is A?×?A despite the coupling strength is varied from zero to a nonzero value. To show this, we prove robust topological mixing on A?×?A. Also, it is of interest that the studied coupled system can exhibit a type of synchronization called generalized partial synchronization which is also robust.     

Preparation and properties of Zn<Subscript>0.9</Subscript>Ni<Subscript>0.1</Subscript>O diluted magnetic semiconductor nanoparticles

With a view to study the structural, electronic, magnetic, and electrical properties of Zn_0.9Ni_0.1O diluted magnetic semiconductor nanoparticles, systematic investigation has been undertaken. Samples were prepared for the first time by hydrazine-assisted polyol method, and the powders were annealed at various temperatures in order to obtain the samples with different grain sizes. From the Rietveld refined XRD data, lattice parameters, the average crystallite size values, and r.m.s micro-strain values were computed. From the AFM and TEM studies, the average particle sizes were obtained and are found to be in the range 12–46 nm. XPS measurements clearly indicate that the chemical states as +2 for both Zn and Ni ions and are stable with varying annealing temperature. Further, using XPS and optical studies, the electronic structure of the materials was analyzed. A careful phase analysis of the Rietveld refined XRD data (at logarithmic scale) selected area electron diffraction patterns, FTIR, Raman, and XPS studies; it was concluded that all the samples are having hexagonal wurtzite structure without any detectable impurity phases. The optical band gap values are found to exhibit a clear blue shift. The influence of oxygen vacancies on the emission spectra was studied by Photo Luminescence measurement. The magnetization studies were undertaken by VSM, MFM, and FMR techniques and confirmed the presence of clear room temperature ferromagnetism without any magnetic clusters. The carrier concentration (n) values obtained from the thermo power studies are found to decrease with increasing annealing temperature and depend on the local defects which are critically influenced by the annealing temperature and crystallite size of the nanomaterials.     

Fibrillar aggregation in cotton cellulose subjected to multiple swelling treatments with alkali

The role of aqueous alkali solutions as swelling agents of cotton cellulose has been studied by various workers and these reagents have been invariably considered to cause lattice disorder in cellulose. The effect of multiple swelling treatments on the cotton cellulose structure has not been studied hitherto. The present study on cotton demonstrates that is the concentration of the swelling agents and the conditions at the time of treatment which determine the resultant order in the final product. The resultant lattice order so attained is shown to be far in excess of any observed in either native or regenerated celluloses or even their hydrolyzed products, with complete retention of their fibrous form. X-ray diffraction and electron microscopy data show conclusively that fibrillar “aggregation” or their “dispersion” can be effectively controlled and are the results of the soda cellulose complexes which form upon alkali treatments. The role of water vis-á-vis the formation of cellulose II is extensively discussed. Studies on sorption and tensile properties of the treated samples lend support to the phenomenon of fibrillar aggregation in cellulosic fibers.     

Microwave synthesis of 1-aryl-1H-pyrazole-5-amines

A microwave-mediated synthesis of 1H-pyrazole-5-amines utilizing 1?M HCl at 150?°C was developed in order to provide products in a matter of minutes with minimal purification. Most reactions are complete in only 10?min and can be isolated via a simple filtration without the need for further purification by column chromatography or recrystallization. This method tolerates a range of functional groups and can be performed on milligram to gram scales.     

Nonlinearities effects on optical MIMO systems

Optical Review - Multimode fibers (MMF) are enjoying a renewed attention boosted by recent advances in multimode complex nonlinear optics. Reason behind nonlinearity is occurred either due to...