ABSTRACTCarnosol and carnosic acid in Rosmarinus officinalis L. were separated by high-performance capillary electrophoresis using a 50 cm capillary, a 12 mmol/L 80:20 pH 9.9 borax:methanol buffer using 25 kV of applied voltage at 30°C with detection at 280 nm. Rosmarinus officinalis L. was extracted with methanol with ultrasound at 170 W and 50 kHz for 20 min. The precision, repeatability, and recovery of the method were evaluated. The calibration relationships for carnosol and carnosic acid were y = 2.331x + 5.92 from 0.01 to 0.160 mg/mL and y = 7.980x + 4.32 from 0.005 to 0.080 mg/mL, respectively. The established method allows the separation and quantification of carnosic acid and carnosol in R. officinalis from various locations in China.

ABSTRACTConventional nuclear magnetic resonance (NMR) instruments are limited by their large volume volume. A miniature NMR spectrometer is reported using a partially enclosed miniature permanent magnet and a low-cost solenoid microcoil probe. The miniature NMR spectrometer uses a sample volume smaller than conventional NMR spectrometers by a factor of 1000. Transverse relaxation times were obtained by the miniature spectrometer using 150 nL of 40 mM copper sulfate, 1 M aqueous sucrose, absolute ethanol, and deionized water. The results demonstrate that high signal-to-noise ratios were obtained. The results were also compared with a commercial NMR spectrometer and suitable accuracy of the laboratory-constructed device was obtained. The miniature NMR spectrometer was employed for the characterization of heated soybean oil. The reported miniature NMR spectrometer is anticipated to have applications for onsite detection.

ABSTRACTScanning tunneling microscopy (STM) was employed to characterize the topography of 32 and 4 µm thick gallium films; thicknesses that have not yet been addressed. The STM images revealed submicron grains on both surfaces although a reduced grain density was observed on the thinner film. The granular structure may be explained by a thin gallium oxide layer that acted as an elastic membrane against liquid gallium underneath that expanded during freezing of the sample. We also believe that the same gallium oxide layer is also responsible for an intriguing effect that appears as soon as the tungsten tip lands on the gallium film: the onset of continuous regular z-oscillations of the tip even at rest. This is an effect that we believe has not been previously reported in the literature. We have also demonstrated, for the first time, a new thickness determination method for the gallium film based on an STM image obtained during the solid-to-liquid phase transition.

ABSTRACTAn optimized voltammetric method is reported for the quantification of ibuprofen in aqueous solution using a carbon paste–multiwalled carbon nanotube composite as the working electrode. The electrode preparation and the experimental conditions were optimized; a sensitivity of 228.08 mA mol−1 L was obtained. The limits of detection and quantification were 9.1 µM and 25.5 µM, respectively, and the linear dynamic range extended from 2.36–242 µM. The repeatability was 5.35% expressed as the relative standard deviation. Using statistical analysis for the lower concentrations, the detection limit was reduced to 4.13 µM. The method was employed for the analysis of ibuprofen tablets.

ABSTRACTIt is necessary to monitor and balance the pulverized coal velocity and flowrate among the conveying pipelines leading to injection burners and to optimize the air-coal ratio for safety, economical operation, and reduction of pollution of coal-fired boilers in power plants. A novel electrostatic sensing system is reported for monitoring the velocity and relative mass flowrate of pulverized coal. The design, implementation, and on-plant trials of the system are reported. The velocity of pulverized coal was determined by autocorrelating the output derived from a linear electrostatic sensor array. The relative concentration and mass flowrate were obtained by the root mean square values of the output of two ring-shaped electrodes with the consideration of the pulverized coal velocity. The instrumentation was evaluated on a full-scale 600 MW power generation unit. The results demonstrate that the technique provides reliable measurement of pulverized coal velocity, relative flowrate, and split distribution among the injection pipes from the same pulverizing mill. The prototype achieved split balance and optimized air/coal ratio in combination with the pulverized coal balancing control valve and proportional-integral-derivative controller in fuel injection pipes in a power plant.

ABSTRACTA method for calibrating the parameters of a small angle X-ray scattering instrument using the diffraction ring of a standard sample is presented. A generalized geometric model for small angle X-ray scattering was constructed and detailed mathematical derivations presented to solve for the relevant instrument parameters, which were then used to convert two-dimensional small angle X-ray scattering data to standard curves. The method is valid regardless whether the detector photosensitive plane is perpendicular or tilted with respect to the beam. Small angle X-ray scattering was performed using standard calibration samples to validate the methodology.

ABSTRACTCobalt boride nanoparticles were deposited on the surface of Mobil Crystalline Material 41 (MCM-41) and the catalytic activity for sodium borohydride hydrolysis was characterized. The transition from cobalt boride particle to cobalt boride layer was evaluated, and the catalytic activity of cobalt boride was improved because of the MCM-41. The catalytic activity increased with the cobalt boride/MCM-41 mass ratio from 1:4 to 1:1. A cobalt boride/MCM-41 mass ratio of 1:1 provided high catalytic activity similar to cobalt boride. Sintered measurements showed that the catalytic activity was from amorphous cobalt boride and not from crystalline cobalt boride. Sintering resulted in the conversion of amorphous cobalt boride to crystalline cobalt boride and damaged the nanostructure of the amorphous cobalt boride framework.

ABSTRACTMorphological, thermal, mechanical, and solvent uptake was characterized for neat nylon 6, 6 and functionalized single-walled carbon nanotube/nylon 6, 6. Single-walled carbon nanotubes were functionalized by acid which introduced carboxyl groups on the nanotubes. Scanning electron micrographs of the fractured surfaces of the nanocomposites suggested that the functionalized single-walled carbon nanotubes were dispersed and embedded within the nylon 6, 6 polymer matrix. Polarized optical micrographs showed that the size of spherulites of the nanocomposites decreased, which may be due to nucleation of the carbon nanotubes. Thermogravimetric analysis showed that the stability of the functionalized single-walled carbon nanotubes/nylon 6, 6 nanocomposites was higher by 28–35°C than neat nylon 6, 6. The uptake of solvent by the functionalized single-walled carbon nanotube/nylon 6, 6 was lower than the neat nylon 6, 6, which may be due to the hydrophobic nature of functionalized single-walled carbon nanotubes and their interaction with the polymer.

ABSTRACTTwo stability-indicating chromatographic methods are reported for the determination of methyl gallate in crude extracts of Bauhinia retusa. Separation by high performance thin layer chromatography was conducted on silica gel aluminum sheets using 9.5:0.5:0.2 (v/v/v) chloroform:methanol:acetic acid at 280 nm. The results from the 2–40 µg/band were used to prepare a linear calibration graph. The limits of detection and quantitation were 0.5 and 1.5 µg/band, respectively. The reverse phase high performance liquid chromatographic isolation of methyl gallate was performed at ambient temperature with an injection volume of 10 μL. The mobile phase consisted of 40:60 (v/v) methanol:0.1% ortho-phosphoric acid. The separation was performed at 1 mL/min using a detection wavelength of 280 nm. The calibration graph for methyl gallate was rectilinear from 0.02–40 µg/mL with limits of detection and quantitation of 0.004 and 0.010 µg/mL, respectively. For both methods, intra-day and inter-day precision were evaluated and the relative standard deviation was less than 2%, indicating good precision. The robustness was evaluated by making small and deliberate changes to appropriate parameters and the calculated relative standard deviation was less than 2%.The chromatographic methods were employed to determine methyl gallate in crude Bauhinia retusa extracts.

ABSTRACTThis article optimizes the conditions for the formation of slow light produced by coupled fiber ring resonators. Investigated parameters include the number of rings, ring length, splitting ratio of couplers, and ring losses. The optimized parameters included two rings in the resonator, equal length of the rings, and splitting ratios of 90:10 and 50:50 for the couplers. Under these conditions, a slow light delay time of 32.0668 ns was achieved, which corresponds to a group velocity of 3.43 × 107 m/s.