Low-angle x-ray estimation of macromolecular parameters of the scattering particles in Agave sisalana

Various macromolecular parameters of Agave sisalana (sisal) fiber were investigated by the low-angle x-ray scattering method. The well known Kratky camera of the latest design was utilized for the experimental measurements. The sample studied was a densely packed colloidal system belonging to a general micelle system, and the theories of Kratky and Kratky and Porod were utilized to estimate the parameters. Pore analysis of the substance yields a value for the specific inner surface of the dispersed phase of 0.406 × 10^?1 m²/cm³; the transversal length is the same as the length of inhomogeneity, 107.31 Å, and the length of coherence is 342.21 Å. The air fraction of the scattering particles was found to be 0.01%.     

Simple, sensitive and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric method for the quantification of lacidipine in human plasma

A simple, sensitive and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric method was developed and validated for the quantification of lacidipine in human plasma using its structural analogue, amlodipine, as internal standard (IS). The method involves a simple single-step liquid-liquid extraction with tert-butyl methyl ether. The analyte was chromatographed on an Xterra MS C(18) reversed-phase chromatographic column by isocratic elution with 20 mM ammonium acetate buffer-acetonitrile (10:90, v/v; pH 6) and analyzed by mass spectrometry in the multiple reaction monitoring mode. The precursor to product ion transitions of m/z 456.4 --> 354.4 and m/z 409.3 --> 238.3 were used to measure the analyte and the I.S., respectively. The chromatographic run time was 1.5 min and the weighted (1/x(2)) calibration curves were linear over the range 0.1-25 ng ml(-1). Lacidipine was sensitive to temperature in addition to light. The method was validated in terms of accuracy, precision, absolute recovery, freeze-thaw stability, bench-top stability and re-injection reproducibility. The limit of detection and lower limit of quantification in human plasma were 50 and 100 pg ml(-1), respectively. The within- and between-batch accuracy and precision were found to be well within acceptable limits (<15%). The analyte was stable after three freeze-thaw cycles (deviation <15%). The average absolute recoveries of lacidipine and amlodipine (IS) from spiked plasma samples were 51.1 +/- 1.3 and 50.3 +/- 4.9%, respectively. The assay method described here could be applied to study the pharmacokinetics of lacidipine.     

Separation of metalloporphyrins from metallation reactions by liquid chromatography and electrophoresis

The analytical separation of the indium and manganese complexes of three synthetic, meso-substituted, water-soluble porphyrins from their respective free bases in metallation reaction mixtures is described. The ligands tetra-3N-methylpyridyl porphyrin, tetra-4N-methylpyridyl porphyrin and tetra-N,N,N-trimethylanilinium porphyrin are complexed with In (III) and Mn (III) and are separated from residual free base by high-performance liquid chromatography (HPLC) in acidic conditions with gradient elution on ODS bonded stationary phase. Electrophoretic separation is achieved on both cellulose polyacetate strips and polyacrylamide tube gels under basic conditions. Although analytical separations can be achieved by both HPLC and electrophoresis, only HPLC is suitable for the development of preparative scale separations. Column chromatography, ion-pairing and ion-suppression HPLC techniques fail to separate such highly charged and closely related aromatic compounds.     

Determination of zirconium,thorium and scandium with 2,5-dihydroxy-1,4-benzoquinone

Zirconium is quantitatively precipitated by 2,5-dihydroxy-1,4-benzoquinone and is separated from scandium in 1 N hydrochloric acid solution. Thorium is separated at pH 0.5 from uranium(VI), cerium(IV), lanthanum, yttrium and scandium. Scandium is quantitatively precipitated by this reagent in the pH range 1.4–2.0 and at pH 1.5 equivalent amounts of lanthanum do not interfere; small amounts of yttrium cause interference.     

Normal coordinate analysis and quantum chemical study of tris(p-fluorophenyl)antimony di(N-phenylglycinate) [(p-FC6H4)3Sb(O2CCH2NHC6H5)2]

A complete normal coordinate analysis was performed by two different methods: a classical Wilson’s G-F matrix method and the semi-empirical molecular orbital PM3 method, for a five coordinate tris(p-fluorophenyl)antimony di(N-phenylglycinate) [(p-FC₆H₄)₃Sb(O₂CCH₂NHC₆H₅)₂], known to be an in vitro antitumour molecule.      

Realization of an advanced nozzle concept for compact chemical oxygen iodine laser

Conventional supersonic chemical oxygen–iodine lasers (SCOIL) are not only low-pressure systems, with cavity pressure of 2–3 Torr and Mach number of approximately 1.5, but also are high-throughput systems with a typical laser power per unit evacuation capacity of nearly 1 J/l, thus demanding high capacity vacuum systems which mainly determine the compactness of the system. These conventional nozzle-based systems usually require a minimum of a two-stage ejector system for realization of atmospheric pressure recovery in a SCOIL. Typically for a 500 W class SCOIL, a first stage requires a motive gas flow (air) of 120 gm/s to entrain a laser gas flow of 3 g/s and is capable of achieving the pressure recovery in the range of 60–80 Torr. On the other hand, the second stage ejector requires 4.5 kg/s of motive gas (air) to achieve atmospheric pressure recovery. An advanced nozzle, also known as ejector nozzle, suitable for a 500 W-class SCOIL employing an active medium flow of nearly 12 g/s, has been developed and used instead of a conventional slit nozzle. The nozzle has been tested in both cold as well as hot run conditions of SCOIL, achieving a typical cavity pressure of nearly 10 Torr, stagnation pressure of approximately 85 Torr and a cavity Mach number of 2.5. The present study details the gas dynamic aspects of this ejector nozzle and highlights its potential as a SCOIL pressure recovery device. This nozzle in conjunction with a diffuser is capable of achieving pressure recovery equivalent to a more cumbersome first stage of the pressure recovery system used in the case of a conventional slit nozzle-based system. Thus, use of this nozzle in place of a conventional slit nozzle can achieve atmospheric discharge using a single stage ejector system, thereby making the pressure recovery system quite compact.     

Broad energy spectrum of laser-accelerated protons for spallation-related physics

A beam of MeV protons, accelerated by ultraintense laser-pulse interactions with a thin target foil, is used to investigate nuclear reactions of interest for spallation physics. The laser-generated proton beam is shown (protons were measured) to have a broad energy distribution, which closely resembles the expected energy spectrum of evaporative protons (below 50 MeV) produced in GeV-proton-induced spallation reactions. The protons are used to quantify the distribution of residual radioisotopes produced in a representative spallation target (Pb), and the results are compared with calculated predictions based on spectra modeled with nuclear Monte Carlo codes. Laser-plasma particle accelerators are shown to provide data relevant to the design and development of accelerator driven systems.     

Lamb wave characteristics of thickness-graded piezoelectric IDT

An equivalent single layer model of Lamb wave generation by thickness-graded piezoelectric IDT on host structure is developed. Various additional complexities, such as the coupling between the Lamb wave modes, complicated nature of the electro-mechanical excitation are considered. The model of infinite IDT is extended to deal with the finite IDT with edge discontinuities. The effects of electromechanical coupling and thickness gradation on the wavelength shifts are investigated. The problem of electrically driven instability within the IDT is analyzed. Numerical results are reported by considering Al2O3/PZT IDT as integral part of the host structure, which show that there are significant changes and improvements in the Lamb wave characteristics due to the graded configuration. Most important among these is the reduced dispersiveness of the Lamb wave modes, which is useful in launching a SAW that propagates with narrower pulse width and less attenuation.     

Mobility of trace elements in soils by thin layer chromatography - Part I

Summary Mobility of some trace elements in a soil under different conditions of leaching has been measured in terms of R_F values with the help of the thin layer method of chromatography. While the iron ions were immobile in a soil of pH 8.8, the mobility of other trace elements was also seriously affected by the presence of Na₂CO₃. Appreciable changes also occurred in the R_F values of the trace elements with the change in the nature and concentration of other leachates. Further the removal of organic matter from the soil resulted in an increase in the movement of the trace elements.

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Zusammenfassung Es wurde die Beweglichkeit von Spurenelementen in Böden gemessen und durch die R_F-Werte mit Hilfe der Dünnschichtchromatographie charakterisiert. Eisen wird bei einem pH von 8,8 unbeweglich. Auch andere Spurenelemente sind im alkalischen Bereich wenig beweglich. Die Entfernung organischer Komponenten aus dem Boden erhöht die Beweglichkeit.