THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …     

Gold‐ and Silver‐Catalyzed Reactions of Propargylic Alcohols in the Presence of Protic Additives

A wide range of primary, secondary and tertiary propargylic alcohols undergo a Meyer–Schuster rearrangement to give enones at room temperature in the presence of a gold(I) catalyst and small quantities of MeOH or 4‐methoxyphenylboronic acid. The syntheses of the enone natural products isoegomaketone and daphenone were achieved using this reaction as the key step. The rearrangement of primary propargylic alcohols can readily be combined in a one‐pot procedure with the addition of a nucleophile to the resulting terminal enone, to give β‐aryl, β‐alkoxy, β‐amino or β‐sulfido ketones. Propargylic alcohols bearing an adjacent electron‐rich aryl group can also undergo silver‐catalyzed substitution of the alcohol with oxygen, nitrogen and carbon nucleophiles. This latter reaction was initially observed with a batch of gold catalyst that was probably contaminated with small quantities of silver salt.     

Nonlinear compression of optical solitons

In this paper, we consider nonlinear Schrödinger (NLS) equations, both in the anomalous and normal dispersive regimes, which govern the propagation of a single field in a fiber medium with phase modulation and fibre gain (or loss). The integrability conditions are arrived from linear eigen value problem. The variable transformations which connect the integrable form of modified NLS equations are presented. We succeed in Hirota bilinearzing the equations and on solving, exact bright and dark soliton solutions are obtained. From the results, we show that the soliton is alive, i.e. pulse area can be conserved by the inclusion of gain (or loss) and phase modulation effects.     

Symplectic supercuspidal representations and related problems

In this paper, we summarize the basic structures and properties of irreducible symplectic supercuspidal representations of GLn(F) over a p-adic local field F with characteristic zero, and explore possible topics for further investigation.     

Weak oblique collisions of interfacial solitary waves

A third order perturbation solution is developed to describe the interaction between two solitary waves approaching each other at an angle close to 180 ° on the interface between two immiscible inviscid homogeneous fluids. The solution is steady in the frame of reference moving with the point of intersection of the waves. To lowest order, the solution consists simply of the superposition of the undisturbed solitary waves. Second-order collision effects include interaction terms localized near the point of intersection and a phase shift in the solitary waves. In addition to corrections to the phase shift and localized interaction terms, third order effects are found to include a wave train that is stationary in the frame of reference moving with the point of intersection of the solitary waves. The amplitudes of the wave train and localized interaction terms diminish with distance from the point of intersection, and the solitary waves recover their initial shape asymptotically long after the collision. Thus, the only long-term effect of the collision is a phase shift.     

Construction of a well-defined multifunctional dendrimer for theranostics

A dendrimer-based building block for theranostics was designed. The multifunctional dendrimer is polyamide-based and contains nine azide termini, nine amine termini, and fifty-four terminal acid groups. Orthogonal functionalization of the multifunctional dendrimer with a near-infrared (NIR) cyanine dye afforded the final dendrimer that shows fluorescence in the NIR region and no toxicity toward T98G human cells. The synthetic strategy described here might be promising for fabricating the next generation of materials for theranostics.     

Identification of impurities in artemisinin, their behavior in high performance liquid chromatography and implications for the quality of derived anti-malarial drugs

Previous work [1] on the HPLC analysis of artemisinin tentatively identified the two impurities present above trace levels. This identification was based on LC-MS results and NMR of impurities isolated from artemisinin. In this work the impurities have been synthesized allowing verification of their identity by LC-MS. It is found that the previously suggested elution order is incorrect. A determination of relative response factors strongly impacts suggested limits on impurity levels and explains the erroneous peak assignment. The fates of the identified impurities are explored in the transformation of artemisinin to its derivative active pharmaceutical ingredients. A survey of a wide variety of artemisinin samples isolated from different geographical regions, different growing seasons, different plant backgrounds and using different extraction and purification approaches showed that artemisinin has sufficient purity for its intended use as a raw material for anti-malarial drug products.     

Electrochromic polymer films containing Re(I) and Pt(II) metal centers

Three Re(I) complexes (3, 5, and 7) (Re(CO)3Cl(L)2) and three new Pt(II) complexes (4, 6, and 8) ([Pt(P(Et)3)2(L)2](OTf)2), where L = pyridine, 1 (4-Py-EDOT) or 2 (4-Py-bithiophene), were prepared and characterized. The solid-state structures of 4 and 5 were determined by X-ray crystallography. Electrochromic polymeric films of 2, 5, and 6 were prepared and characterized.