Vibrational behavior of adsorbed CO2 on single-walled carbon nanotubes

We present theoretical and experimental evidence for CO(2) adsorption on different sites of single walled carbon nanotube (SWNT) bundles. We use local density approximation density functional theory (LDA-DFT) calculations to compute the adsorption energies and vibrational frequencies for CO(2) adsorbed on SWNT bundles. The LDA-DFT calculations give a range of shifts for the asymmetric stretching mode from about -6 to -20 cm(-1) for internally bound CO(2), and a range from -4 to -16 cm(-1) for externally bound CO(2) at low densities. The magnitude of the shift is larger for CO(2) adsorbed parallel to the SWNT surface; various perpendicular configurations yield much smaller theoretical shifts. The asymmetric stretching mode for CO(2) adsorbed in groove sites and interstitial sites exhibits calculated shifts of -22.2 and -23.8 cm(-1), respectively. The calculations show that vibrational mode softening is due to three effects: (1) dynamic image charges in the nanotube; (2) the confining effect of the adsorption potential; (3) dynamic dipole coupling with other adsorbate molecules. Infrared measurements indicate that two families of CO(2) adsorption sites are present. One family, exhibiting a shift of about -20 cm(-1) is assigned to internally bound CO(2) molecules in a parallel configuration. This type of CO(2) is readily displaced by Xe, a test for densely populated adsorbed species, which are expected to be present on the highest adsorption energy sites in the interior of the nanotubes. The second family exhibits a shift of about -7 cm(-1) and the site location and configuration for these species is ambiguous, based on comparison with the theoretical shifts. The population of the internally bound CO(2) may be enhanced by established etching procedures that open the entry ports for adsorption, namely, ozone oxidation followed by annealing in vacuum at 873 K. Xenon displacement experiments indicate that internally bound CO(2) is preferentially displaced relative to the -7 cm(-1) shifted species. The -7 cm(-1) shifted species is assigned to CO(2) adsorbed on the external surface based on results from etching and Xe displacement experiments.     

"Tethered" Ru(II) catalysts for asymmetric transfer hydrogenation of ketones

Stereochemically well-defined ruthenium(II) catalysts have been applied to the asymmetric transfer hydrogenation of a series of ketones. In one case, statistical experimental design was employed to optimize the enantiomeric excess of the product. In the case of the TsDPEN-based systems, the replacement of trans-1,2-diphenyl substitution with cis-, or deletion of one of the phenyl groups, results in significant deterioration of the enantiomeric excess. A new method is described for the synthesis of tethered amino alcohol-containing catalysts.     

Production of the neutron-rich hypernucleus 10LambdaLi in the (pi-,K+) double charge-exchange reaction

In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing the (pi-,K+) double charge-exchange reaction on a 10B target. We observed the production of a 10LambdaLi hypernucleus. The cross section for the Lambda bound region was found to be 11.3+/-1.9 nb/sr with the 1.2 GeV/c incident momentum, which is compared with the 10LambdaB hypernucleus production cross section, 7.8+/-0.3 microb/sr, in the (pi+,K+) reaction with a 1.05 GeV/c incident momentum beam.     

Applicability of X-ray microscopy to non-contact tablet mass estimation

The pharmaceutical tablet manufacturing process requires a tablet mass measuring step to ensure that all tablets have the prescribed dosage. The digital scales commonly used for that purpose require tens of seconds to stabilize, resulting in a substantial slow-down of the manufacturing process. The alternative visual approaches are fallible because of the potential existence of voids and cracks in the tablets. This paper uses an X-ray microscopy for mass measurement. Albeit with some constraints concerning tablet size and constituents, the approach can measure a tablet’s mass in under one second, and may constitute, in the future, a viable and practical approach.     

Control of noisy chaotic motion in a system with nonlinear excitation and restoring forces

In this study we examine the complex and chaotic oscillations of a dynamical system with nonlinear excitation and restoring forces for the purpose of controlling these oscillatory states. The physical system, modeled as a system of first-order nonlinear ordinary differential equations, takes into account a geometric nonlinearity in the restoring force, a quadratic viscous drag, and a harmonic excitation force. It is controlled using small perturbations about a selected unstable cycle and control is instigated for periodic cycles of varying periodicities. The controller, when applied on the dynamical system with additive random noise in the excitation, successfully controls the system with noise levels in excess of 5% of the total energy, giving the first evidence that (stochastic) control of these systems is possible. (c) 1997 American Institute of Physics.     

Quantified High-Throughput Screening of Escherichia coli Producing Poly(3-hydroxybutyrate) Based on FACS

Here, we report on a highly sensitive method for the detection of P(3HB) accumulation in Escherichia coli cells based on the automated flow cytometry system using fluorescent dyes. E. coli containing P(3HB) were stained with either BODIPY or Nile red fluorescent dye, and their staining properties were analyzed under a variety of conditions. Compared with Nile red, BODIPY was much more sensitive in staining P(3HB) and overall demonstrated a more rapid staining of cells, a greater resistance to photobleaching, and greater cell viability. In addition, we also successfully monitored heterogeneity in P(3HB) accumulation within a cell population using BODIPY staining and flow cytometry. We believe this optimized staining method using BODIPY in combination with screening by high-speed flow cytometer will be helpful in the engineering of host cells toward an enhanced production of bioplastics.     

Application of a rapid and selective method for the simultaneous determination of carebastine and pseudoephedrine in human plasma by liquid chromatography–electrospray mass spectrometry for bioequivalence study in Korean subjects

We describe a simple, rapid and sensitive high‐performance liquid chromatography–electrospray ionization tandem mass spectrometric method that was developed for the simultaneous determination of carebastine and pseudoephedrine in human plasma using cisapride as an internal standard. Acquisition was performed in multiple‐reaction monitoring mode by monitoring the transitions: m/z 500.43 > 167.09 for carebastine and m/z 166.04 > 147.88 for pseudoephedrine. The devised method involves a simple single‐step liquid–liquid extraction with ethyl acetate. Chromatographic separation was performed on a C₁₈ reversed‐phase chromatographic column at 0.2 mL/min by isocratic elution with 10 mM ammonium formate buffer–acetonitrile (30:70, v/v; adjusted to pH 3.3 with formic acid). The devised method was validated over 0.5–100 ng/mL of carebastine and 5–1000 ng/mL of pseudoephedrine with acceptable accuracy and precision, and was successfully applied to a bioequivalence study involving a single oral dose (10 mg of ebastine plus 120 mg of pseudoephedrine complex) to healthy Korean volunteers. Copyright © 2010 John Wiley & Sons, Ltd.     

Real-time on-line ultrasonic monitoring for bubbles in ceramic ‘slip’ in pottery pipelines

When casting ceramic items in potteries, liquid ‘slip’ is passed from a settling tank, through overhead pipelines, before being pumped manually into the moulds. It is not uncommon for bubbles to be introduced into the slip as it passes through the complex piping network, and indeed the presence of bubbles is a major source of financial loss to the ceramics industry worldwide. This is because the bubbles almost always remain undetected until after the ceramic items have been fired in a kiln, during which process bubbles expand and create unwanted holes in the pottery. Since there it is usually an interval of several hours between the injection of the slip into the moulds, and the inspection of the items after firing, such bubble generation goes undetected on the production line during the manufacture of hundreds or even thousands of ceramic units. Not only does this mean hours of wasted staff time, power consumption and production line time: the raw material which makes up these faulty items cannot even be recycled, as fired ceramic cannot be converted back into slip.Currently, the state-of-the-art method for detecting bubbles in the opaque ceramic slip is slow and invasive, can only be used off-line, and requires expertise which is rarely available. This paper describes the invention, engineering and in-factory testing across Europe of an ultrasonic system for real-time monitoring for the presence of bubbles in casting slip. It interprets changes in the scattering statistics accompanying the presence of the bubbles, the latter being detected through perturbations in the received signal when a narrow-band ultrasonic probing wave is transmitted through the slip. The device can be bolted onto the outside of the pipeline, or used in-line. It is automated, and requires no special expertise. The acoustic problems which had to be solved were severe, and included making the system capable of monitoring the slip regardless of the material of pipe (plastic, steel, etc.) and nature of the slip (which can be very variable). It must also be capable of detecting bubbles amongst the myriad solid particles and other species present in the flowing slip. The completed prototype was tested around several factories in Europe, and proved not only to be more versatile, but also more sensitive, than the state-of-the-art method.