Analysis of a shielded TE011 mode composite dielectric resonator for stable frequency reference

Analysis of a TE₀₁₁ mode composite sapphire-rutile dielectric resonator has been carried out to study the temperature variation of resonance frequency, close to the Cs atomic clock hyperfine frequency of 9.192 GHz. The complementary behavior of dielectric permittivity with temperature of the composite has been exploited to obtain the desired turning point in the resonant frequency. The frequency of the composite structure is found to be independent of the shield diameter beyond four times the puck diameter.     

Large-scale purification of single-wall carbon nanotubes: process, product, and characterization

Received: 13 February 1998     

Increasing high‐throughput Discovery bioanalysis using automated selected reaction monitoring compound optimization,ultra‐high‐pressure liquid chromatography,and single‐step sample preparation workflows

QuickQuan is an integrated software package for Thermo Scientific triple quadrupole mass spectrometers that allows users to automate routine operations ranging from method development to data processing. QuickQuan automated optimization of compound‐selected reaction monitoring (SRM) transitions by evaluating both positive and negative polarities during an infusion. Whichever mode produces the most intense Q1 scan is then carried to product ion spectra. QuickQuan then writes these SRM methods to a shared network database. The total volume of compound needed is 100 µL infused over approximately 1.6 min. The auto‐optimization is carried out in 96‐well plates and does not require an operator present. The SRM database was shared between two identical TSQ Quantum mass spectrometers. For data acquisition, QuickQuan automatically created a sequence file complete with a data processing method pre‐populated with compound IDs and corresponding SRM transitions. To increase throughput we coupled each Finnigan Quantum with ultra‐high‐pressure liquid chromatography (uHPLC) accomplished using 4× Ultra Flux quaternary pumps that were designed to handle pressures up to 15 000 psi. The total run time for all analyses was 1.2 min using BEH 1.7 µm particle C18 columns. Further time reductions were realized with sample preparation accomplished using Strata Impact protein precipitation plates which provided an in‐well protein crash and 0.20 micron filtering in a one‐step process. Pharmacokinetic data turnaround time was significantly improved by combining these three techniques of automated method development with the speed efficiency of uHPLC and a single step in well sample preparation. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermoelectric power of p-doped single-wall carbon nanotubes and the role of phonon drag

We measured thermoelectric power S of bulk single-wall carbon nanotube materials p doped with acids. In contrast to oxygen-exposed or degassed samples, S is very small at the lowest temperatures, increases superlinearly above a characteristic and sample-dependent T, and then levels off. We attribute this unusual behavior to 1D phonon drag, in which the depression of the Fermi energy cuts off electron-phonon scattering at temperatures below a characteristic T0. This idea is supported by a model calculation in which the low temperature behavior of phonon drag is specifically related to the one-dimensional character of the electronic spectrum.     

A theoretical introduction to the development of a unified approach to flexible rotor balancing

Several successful methods for balancing flexible rotating shafts have been developed in recent years, whose relative merits have been the subject of much debate and argument. These methods can be separated into two, seemingly distinct, groups which can be concisely identified as modal balancing and influence coefficient techniques. The present authors consider that in practice many of the differences are more apparent rather than real and that the time has arrived for an attempt to reconcile the differences and hopefully to synthesize a method which includes the best features of both methods. This paper reviews the theoretical basis for this programme. The results of a preliminary experimental exploration have been recorded elsewhere.     

Integral versus local conservation laws in metric theories of gravity

Previously we considered extensions of metric theories of gravitation with non-zero divergence of the energy-momentum tensor. We confirm here that lack of local conservation laws does not exclude, a priori, existence of integral conservation laws.     

A highly selective, one-pot purification method for single-walled carbon nanotubes

We report on a one-pot, highly selective chemistry to remove residual catalysts from single-walled carbon nanotubes (SWNTs). The impurities, initially present at approximately 35 wt % and mostly as carbon-coated iron nanoparticles, can be driven below 5 wt % with nearly no loss of SWNTs. The carbon-coated iron impurities are dissolved simply by reacting with an aqueous mixture of H2O2 and HCl at 40-70 degrees C for 4-8 h. This purification combines two known reactions involving H2O2 and HCl, respectively; however, by combining these two typically inefficient reactions into a one-pot reaction, the new process is surprisingly selective toward the removal of the metal impurities. This high selectivity derives from the proximity effect of the iron-catalyzed Fenton chemistry. At pH approximately 1-3, iron is dissolved upon exposure, avoiding the otherwise aggressive iron-catalyzed digestion of SWNTs by H2O2. This extremely simple and selective chemistry offers a "green" and scalable process to purify carbon nanotube materials.     

Riemann curvature tensor in nonholonomic coordinates and non-Riemannian space-times

The calculation of the Riemann Curvature from the deviation of a vector undergoing parallel transport around a closed loop takes a very simple form when expressed in generalized geometrical notation. We discuss the parallel transport of a vector and the type of closed loop used in the calculation. Our method generalizes similar work of Morganstern, to nonholonomic coordinates and non-Riemannian space-times.     

A spin polarized disc. II

We present a solution to the gravitational field equations which describes either a static disc in general relativity or a spin polarized rotating disc in a Riemann-Cartan spacetime. The disc has infinite radius and finite thickness. The energy and pressure are finite and positive within the disc and for some parameter choices, a radial fall off in the fluid parameters is possible. A comparison is made to axis-symmetric wall solutions.     

Base-induced intramolecular cyclisation of o-azidophenyl sec-alkyl ketones. A new synthesis of 2,2-dialkylindoxyls

$\text{o}$-Azidophenyl $\text{sec}$-alkyl ketones in ethanolic potassium hydroxide at room temperature cyclise in high yield to 2,2-dialkylindoxyls.