Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I.

The stereoselective total synthesis of strongylodiol H and I has been accomplished. The synthetic procedure comprised the stereoselective reduction of a ketone functionality in an ene-yne-one employing CBS as a catalyst and a Cadiot-Chodkiewicz coupling reaction as the key reaction steps. A common aldehyde intermediate has been used for the synthesis of both strongylodiols.

Facile hydrothermal synthesis of urchin-like cobalt manganese spinel for high-performance supercapacitor applications.

A facile hydrothermal method has been adopted to synthesize the spherical urchin-like hierarchical CoMnO nanostructures on the nickel foam substrate. The as-synthesized urchins have an average diameter of ∼3-7μm with numerous self-assembled nanoneedles grown radically in all the directions from its center with a huge void space between them. For comparison, we have also studied the electrochemical as well as other physicochemical properties of parent simple CoO and MnO materials, which were also synthesized by a similar hydrothermal method.

Para amino benzoic acid-derived self-assembled biocompatible nanoparticles for efficient delivery of siRNA.

A number of diseases can result from abnormal gene expression. One of the approaches for treating such diseases is gene therapy to inhibit expression of a particular gene in a specific cell population by RNA interference. Use of efficient delivery vehicles increases the safety and success of gene therapy.

Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis.

Hydrothermal fabrication of selectively doped (Ag(+)+Pd(3+)) advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions (autogeneous; 150°C). Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr.

Evaluation of thermophysical properties of ionic liquids with polar solvent: a comparable study of two families of ionic liquids with various ions.

In this work, we explore and compare the role of the ion effect on the thermophysical properties of two families of ionic liquids (ILs), namely, tetra-alkyl ammonium cation [R4N](+) with hydroxide [OH](-) anion and 1-alkyl-3-methyl imidazolium cation [amim](+) with different anions (chloride, methyl sulfate, and tetrafluoroborate), with polar solvent such as dimethylsulfoxide (DMSO) in the temperature range from 25 to 40 °C and over the whole concentration range of ILs. Two families of ILs, namely, tetramethyl ammonium hydroxide [(CH3)4N][OH] (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N][OH] (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N][OH] (TPAH), and tetrabutyl ammonium hydroxide [(C4H9)4N][OH] (TBAH) from ammonium-based ILs and 1-ethyl-3-methylimidazolium chloride [Emim][Cl], 1-ethyl-3-methylimidazolium methylsulfate [Emim][MeSO4], 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4], and 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) from imidazolium family of ILs, are used in the present study. To address the molecular interactions of ILs with DMSO, densities (ρ), ultrasonic sound velocities (u), and viscosities (η) have been measured over the entire composition range and at four temperatures, 25, 30, 35, and 40 °C, under atmospheric pressure.

Ultrasonic Studies on Molecular Interactions in Binary Mixtures of -Methyl Aniline with Methyl Isobutylketone, +3-Pentanone, and +Cycloalkanones at 303.15 K.

Densities, , viscosities, , and ultrasonic sound velocities of pure methyl isobutylketone, diethylketone, cyclopentanone, cyclohexanone, 2-methyl cyclohexanone and those of their binary mixtures with -methyl aniline were measured at 303.15 K over the entire composition range. These experimental data have been used to calculate the excess volume (), deviation in ultrasonic sound velocity (∆), isentropic compressibility ( ), intermolecular free length (), excess intermolecular free length ([Formula: see text]), acoustic impedance (), excess isentropic compressibility ([Formula: see text]), deviation in viscosity (∆) and excess Gibbs energy of activation of viscous flow ().

Selective and sensitive method for the determination of metoprolol in human plasma using liquid chromatography coupled with tandem mass spectrometry.

A high-performance liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of metoprolol in human plasma. The analyte and internal standard, nevirapine, were extracted from plasma matrix by liquid-liquid extraction with ethyl acetate. Chromatographic separation was achieved on a C-18 analytical column with an isocratic mobile phase of 15:85 (V/V) 10 mmol L-1 ammonium acetate (pH 5.

High performance liquid chromatography/negative ion electrospray tandem mass spectrometry method for the measurement of hydrochlorothiazide in human plasma: application to a comparative bioavailability study.

A sensitive, selective and rapid liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of hydrochlorothiazide (HCTZ) in human plasma. The plasma samples were prepared by solid phase extraction using Oasis HLB 30 mg 1CC cartridges. Chromatographic separation was accomplished on a Thermo Hypurity Advance (50 mm x 4.

Rapid high-performance liquid chromatography-tandem mass spectrometry method for simultaneous measurement of venlafaxine and O-desmethylvenlafaxine in human plasma and its application in comparative bioavailability study.

A rapid high-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for simultaneous measurement of venlafaxine and O-desmethylvenlafaxine in human plasma using fluoxetine as an internal standard. In the liquid-liquid extraction method, compounds and internal standard were extracted from plasma using methyl tertiary butyl ether as an extraction solvent. The HPLC separation of the analytes was performed on a Zorbax SB-C(18), 50 x 4.

Removal of mercury from aqueous solutions using activated carbon prepared from agricultural by-product/waste.

Removal of mercury from aqueous solutions using activated carbon prepared from Ceiba pentandra hulls, Phaseolus aureus hulls and Cicer arietinum waste was investigated. The influence of various parameters such as effect of pH, contact time, initial metal ion concentration and adsorbent dose for the removal of mercury was studied using a batch process. The experiments demonstrated that the adsorption process corresponds to the pseudo-second-order-kinetic models and the equilibrium adsorption data fit the Freundlich isotherm model well.

An occupational exposure assessment of a perfluorooctanesulfonyl fluoride production site: biomonitoring.

This investigation randomly sampled a fluorochemical manufacturing employee population to determine the distribution of serum fluorochemical levels according to employees' jobs and work areas. Previous analyses of medical surveillance data have not shown significant associations between fluorochemical production employees' clinical chemistry and hematology tests and their serum PFOS and perfluorooctanoate (PFOA, C(7)F(15)COO(-)) concentrations, but may have been subject to nonparticipation bias. A random sample of the on-site film plant employee population, where fluorochemicals are not produced, determined their serum concentrations also.

Continuous-wave laser beam fanning in organic solutions: a novel phenomenon.

If a low-power cw Ar(+) laser beam (~50 mW) is sent horizontally and focused on the entrance side of a cuvette containing an absorptive solution, the beam fans into the lower half of the cuvette instead of propagating through and forming self-phase-modulation fringes. We call this phenomenon self-beam fanning, which has been observed in several organic solutions. We present here several experimental results and a descriptive model of the phenomenon.

Four-photon-mixing-mediated stimulated Raman scattering in a multimode optical fiber.

Stimulated Raman scattering with 532-nm pulsed laser light is investigated in a 7.9-microm-core step-index multimode fiber. While low-intensity pump or single-mode LP(01) excitation produces the usual stimulated Raman scattering light, mixed-mode (LP(01) + LP(02)) excitation with pump intensities of ~5 kW uniformly shifts the multiorder Stokes Raman spectrum by an amount determined by fiber parameters, thus making stimulated Raman scattering tunable.

Determination of fluorine in biological materials: a review.

This review on determination of fluorine in biological materials briefly covers (a) a discussion of various forms of fluorine in body fluids and tissues [and also in foods]; (b) methods of their determination, including pretreatment of samples, separation and concentration of F and its final measurement; (c) an evaluation of the analytical methods used and interpretation of results; and (d) some recommendations for future research in fluorine analytical methods applicable to biological materials.

Optical phase conjugation in polycarbonate resin doped with Coumarin 314 dye.

Optical phase conjugate wave generation in Coumarin 314-doped polycarbonate resin is investigated by using 488-nm light for writing the grating and 632.8-nm light for reading it. The observed oscillatory behavior of grating growth as a function of writing time is attributed to heating effects.

Laser beam collimation using Talbot interferometry.

A modified method of checking laser beam collimation by using Talbot interferometry coupled with a moir6 phenomenon is described.

Energy-transfer measurement and determination of the phase shift between the holographic grating and the fringe pattern in photorefractive materials.

We describe a novel accurate method to measure energy transfer between two beams coupling in photorefractive materials. We have used this method to measure the on-line energy-transfer signal in an electrically poled BaTiO(3) crystal and to record the growth of the grating responsible for energy transfer. We also used this technique to determine the phase shift between the grating that is written in the crystal and the fringe pattern responsible for writing that grating.

Compact in-line laser radial shear interferometer.

A compact in-line radial shearing interferometer using laser as a light source is presented. The interferometer is made out of a cube-type beam splitter so that the two opposite surfaces are generated with different curvatures while the normal to the entrance and exit surfaces are in the same line. The interferometer is simple to make and easy to align.

Separation of fluoride from fluoroelastomers by diffusion in test tubes.

The conventional procedure for separation of fluoride as trimethylfluorosilane in Conway diffusion cells involves the use of grease for sealing the cell and also for closing the hole in the lid drilled for introduction of hexamethyldisiloxane. We have developed a simpler procedure in which diffusion is carried out in 5-mL test tubes without the use of grease. Results of analysis of fluoride following diffusion from water, urine, and bone samples are in excellent agreement with those obtained by other procedures not involving diffusion.

Determination of refractive index of a simple negative, positive, or zero power lens using wedged plated interferometer.

Measurement of the refractive index of a simple negative lens is presented. The technique is also useful for measuring the refractive index of a simple convex and zero power lens.

Evaluation of analytical methods for fluorine in biological and related materials.

During the past two decades, some major pitfalls in fluorine analysis have been recognized and overcome. Therefore, it is important that facts be separated from fallacies in published literature on levels and forms of fluorine (ionic, bound, covalent, etc.) in biological materials, in order that correct perceptions of physiological, biochemical, and toxicological aspects of inorganic as well as organic fluorine compounds can be formed.

Optical bistability in self-pumped phase-conjugate ring resonators.

Bistable oscillations have been observed in BaTiO(3) pumped by a single-mode 30-mW (488-nm) argon-ion laser, which is used simultaneously as a ring passive phase conjugator (RPPC) and as a unidirectional ring resonator (UDRR). Strong oscillations in the UDRR increase the threshold coupling strength required for oscillation in the RPPC. The oscillations in the RPPC reduce the fanning in the crystal necessary for the startup of oscillation in the UDRR.