Measurement of the linear viscoelastic behavior of antimisting kerosene

Measurements of dynamic viscoelastic properties in very small oscillating shear deformations was made on solutions of a jet fuel, Jet A, containing an antimisting polymeric additive, FM-9. A few measurements were also made on solutions of FM-9 in a mixed solvent of mineral oil, Tetralin, and 0-terphenyl. Two samples of FM-9 had approximate number-average molecular weights of 12,000,000 and 8,100,000 as deduced from analysis of the measurements. The ranges of variables were 2.42 to 4.03 g/1 in concentration (0.3 to 0.5% by weight), 1 to 35 in temperature, 1.3 to 9.4 cp in solvent viscosity, and 103 to 6100 Hz in frequency. Measurements in the Jet A solvent were made both with and without a modifying carrier. The results were compared with the Zimm theory and the viscoelastic behavior was found to resemble rather closely that of ordinary non-polar polymers in theta solvents. The relation of the results to the antithixotropic behavior of such solutions a high shear rates is discussed in terms of intramolecular and intermolecular interactions

On the mechanism of the highly viscous flow

The asymmetry model for the highly viscous flow postulates thermally activated jumps from a practically undistorted ground state to strongly distorted, but stable structures, with a pronounced Eshelby backstress from the distorted surroundings. The viscosity is ascribed to those stable distorted structures which do not jump back, but relax by the relaxation of the surrounding viscoelastic matrix. It is shown that this mechanism implies a description in terms of the shear compliance, with a viscosity which can be calculated from the cutoff of the retardation spectrum. Consistency requires that this cutoff lies close to the Maxwell time. The improved asymmetry model compares well with experiment.Comment: 8 pages, 3 figures, 49 references; revised version accepted in Journal of Chemical Physic

A profile of the Monterey squid fleet in 1992

There were approximately 20 vessels active in the 1992 Monterey Bay squid fishery. The size of the fleet has not changed since the early 1970's when 15 to 20 vessels participated in the fishery. Since 1977, eleven steel hulled vessels have been added to the fleet, replacing smaller wooden hulled vessels that were in use during the 1960's. The hold capacity of the new fleet remains about 800 tons, because the new larger vessels replaced small vessels that used lighters (20 - 25 ton capacity non-motorized barges). Purse seines were legalized in 1989 and have replaced lamparas which were in use during the 1960'S and 1970's. Seines used in the squid fishery are small and shallow, ranging from 120 to 200 fm in length with most less than 25 fm deep. Crew size has been reduced nearly 50% by the addition of net reels, power blocks, submersible fish pumps, and vacuum pumps used for unloading at dockside. In the 1970's flasher type fathometers were used by the fleet and few vessels had navigational aids. Today most of the fleet have sonar, radar, and loran C. Three vessels carry global positioning systems. In 1988 squid attracting lights were legalized and the entire fleet used lights during the 1992 season. (21pp.

DNA double helices for single molecule electronics

The combination of self-assembly and electronic properties as well as its true nanoscale dimensions make DNA a promising candidate for a building block of single molecule electronics. We argue that the intrinsic double helix conformation of the DNA strands provides a possibility to drive the electric current through the DNA by the perpendicular electric (gating) field. The transistor effect in the poly(G)-poly(C) synthetic DNA is demonstrated within a simple model approach. We put forward experimental setups to observe the predicted effect and discuss possible device applications of DNA. In particular, we propose a design of the single molecule analog of the Esaki diode.Comment: 4 pages, 4 figur

Spin-dependent pump current and noise in an adiabatic quantum pump based on domain walls in a magnetic nanowire

We study the pump current and noise properties in an adiabatically modulated magnetic nanowire with double domain walls (DW). The modulation is brought about by applying a slowly oscillating magnetic and electric fields with a controllable phase difference. The pumping mechanism resembles the case of the quantum dot pump with two-oscillating gates. The pump current, shot noise, and heat flow show peaks when the Fermi energy matches with the spin-split resonant levels localized between the DWs. The peak height of the pump current is an indicator for the lifetime of the spin-split quasistationary states between the DWs. For sharp DWs, the energy absorption from the oscillating fields results in side-band formations observable in the pump current. The pump noise carries information on the correlation properties between the nonequilibrium electrons and the quasi-holes created by the oscillating scatterer. The ratio between the pump shot noise and the heat flow serves as an indicator for quasi-particle correlation.Comment: 18 pages, 5 figure

Constitutional Law - Criminal Procedure - Right to Counsel at Lineup

The United States Supreme Court has held that a lineup conducted prior to indictment is not a critical stage of the prosecution and therefore the sixth amendment right to counsel is not applicable. Kirby v. Illinois, 406 U.S. 682 (1972)

SIGNIFICANCE EVALUATION OF THE FORGOTTEN CREEK SITE

Archaeological research has recognized the importance of montane environments in the subsistence and settlement strategies of pre-contact peoples. Yet little is understood about variation in the manner in which pre-contact peoples were using upland environments. In order to ascertain whether there is functional and/or technological variation between montane sites in comparable environmental settings, four lithic assemblages (45PI406, 45PI408, 45PI429, and 45PI438) from sites in the upper maritime forest and subalpine zone of Mount Rainier were compared. An evolutionary archaeology model was applied to define and measure variables relevant to stone tool manufacture and use. Statistically significant non-random associations were contextualized within the known environmental constraints and regional land use models for upland subsistence and settlement strategies in the southern Washington Cascades. Overall results indicate that the assemblages are dominated by debitage, and are consistent with those produced as a result of tool manufacture by semi-sedentary groups at limited activity sites. However, the assemblages differ synchronically in both technological and functional organization, indicating that local microenvironments and climate regimes significantly influenced stone tool manufacture and use

Improvement of current-control induced by oxide crenel in very short field-effect-transistor

A 2D quantum ballistic transport model based on the non-equilibrium Green's function formalism has been used to theoretically investigate the effects induced by an oxide crenel in a very short (7 nm) thin-film metal-oxide-semiconductor-field-effect-transistor. Our investigation shows that a well adjusted crenel permits an improvement of on-off current ratio Ion/Ioff of about 244% with no detrimental change in the drive current Ion. This remarkable result is explained by a nontrivial influence of crenel on conduction band-structure in thin-film. Therefore a well optimized crenel seems to be a good solution to have a much better control of short channel effects in transistor where the transport has a strong quantum behavior

Morphology and structure of soot emitted from various aircraft engines

International audienceWe present here an experimental characterization of the morphology, structure and chemical properties of soot particles emitted from various aircraft engines (CFM56-5C, -7B, SaM-146), and a combustor [Delhaye, 2008 ; Petzold, 2011]. Soot particles have been collected by direct impaction on electron microscope grids. Transmission electron microscopy (TEM) is used to determine the aggregates fractal dimension as well as soot primary particles and aggregates size distributions. The morphology, structure and texture of primary particles are also determined in addition to the elemental composition by the mean of X-ray energy dispersive spectrometry (XREDS)