Migration arising from gradients in shear stress: Particle distributions in Poiseuille flow

Experimental evidence for the existence of shear induced migration processes is reviewed and the mechanism by Leighton and Acrivos (1987b) is described in detail. The proposed mechanism is shown to lead to the existence of an additional shear induced migration in the presence of gradients in shear stress such as would be found in Poiseuille flow, and which may be used to predict the amplitude of the observed short-term viscosity increase. The concentration and velocity profiles which result from such a migration are discussed in detail and are compared to the experimental observations of Karnis, Goldsmith and Mason (1966)

Solar array flight experiment/dynamic augmentation experiment

This report presents the objectives, design, testing, and data analyses of the Solar Array Flight Experiment/Dynamic Augmentation Experiment (SAFE/DAE) that was tested aboard Shuttle in September 1984. The SAFE was a lightweight, flat-fold array that employed a thin polyimide film (Kapton) as a substrate for the solar cells. Extension/retraction, dynamics, electrical and thermal tests, were performed. Of particular interest is the dynamic behavior of such a large lightweight structure in space. Three techniques for measuring and analyzing this behavior were employed. The methodology for performing these tests, gathering data, and data analyses are presented. The report shows that the SAFE solar array technology is ready for application and that new methods are available to assess the dynamics of large structures in space

CULTIVATING OPPORTUNITIES FOR AT-RISK YOUTH AND NUTRITIOUS FOOD FOR THE COMMUNITY

Garden City Harvest is a Missoula, Montana nonprofit organization. Garden City Harvest sponsors the Youth Harvest program. Youth Harvest teaches at-risk youth job and life skills. The program’s mission is to improve participants’ professional and personal outcomes as adults. Participants utilize farming and retail skills they learn in the program to improve their employment opportunities and learn important life skills, such as money management, nutritional literacy, and food preparation. Participants also have the opportunity to assist other vulnerable people in Missoula and to become more connected to their communities. This paper is an analysis of questionnaires that Youth Harvest staff distribute to adolescents in the program. Those questionnaires are designed to measure if Youth Harvest is meeting its goals. This analysis suggests that Youth Harvest is mostly successful in helping youth achieve professional and personal goals, but there is room for improvement

Fluorescence Lifetime Discrimination of Near-Infrared Dye-Labeled Oligonucleotide Fragments Separated by Capillary Gel Electrophoresis for Base-Calling Applications in DNA Sequencing.

The research presented in this dissertation involves the construction of a near-infrared time-correlated single photon counting system which utilizes a mode-locked Ti:sapphire or pulsed diode laser as the excitation source and single photon avalanche diode as the photodetector and the subsequent study of two simple algorithms, the Maximum Likelihood Estimator (MLE) and the Rapid Lifetime Determination (RLD) methods, for fluorescence lifetime determination. The purpose of this research is to aid in the development of a low cost, highly efficient, and high throughput device for DNA sequencing which utilizes near-IR fluorophores which have similar absorption and emission properties but possess unique fluorescence lifetimes, which will allow the identity of the terminal base to be accomplished by lifetime discrimination. The performance of the MLE and RLD for measuring nanosecond and subnanosecond fluorescence lifetimes were evaluated in static solutions in the limits of low concentrations and high backgrounds from scattered photons generated from the solvent using experimental and Monte Carlo simulation results. The conclusions from these results were used in the on-line determinations of fluorescence lifetimes of components separated via capillary electrophoresis. For example, a capillary gel electrophoretic separation of near-IR dye-labeled C-terminated fragments was done with decay profiles of the separated fragments collected. The MLE lifetime value for decay profiles collected from 35 individual peaks was 581 $\pm$ 9 ps, which agreed with the high concentration value (\tau\sb{f}=581 ps). Also, a pulsed-diode laser based instrument with the counting electronics situated on a PC board was constructed and its performance evaluated by a CGE separation of A- and C-terminated DNA fragments. The results indicated lifetime values of 669 $\pm$ 42 ps and 528 + 68 ps for the A-terminated and C-terminated fragments, respectively, for the MLE. In order to study the effects of peak resolution on the fluorescence lifetime determination, Monte Carlo simulations were used to study the effect of electrophoretic resolution between peaks on the calculated lifetime using both the MLE and RLD algorithms. In addition, accuracy and precision were analyzed for the calculated lifetimes during the electrophoresis as a function of integration time

Viscosity-Temperature Relations of Naphthalene in Benzene

A study was made of multi-benzene ring compounds dissolved in benzene in order to discover any relationship between viscosity, density, and temperature. However, as there was insufficient time, only solutions of naphthalene dissolved in benzene were studied

Binary Oscillatory Crossflow Electrophoresis

Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that solute is drawn into the cell from reservoirs at both ends of the cell leading to a large mass build up. As a consequence, any initially induced mass flux will vanish after short times. This effect was not captured by the infinite channel model and hence numerical and experimental results deviated significantly. The revised model including finite cell lengths and reservoir volumes allowed quantitative predictions of the time history of the concentration profile throughout the system. This latter model accurately describes the fluxes observed for both oscillatory flow modes in experiments using single protein species. Based on the results obtained from research funded under NASA grant NAG-8-1080.S, we conclude that binary separations are not possible using purely oscillatory flow modes because of end effects associated with the cos((omega)t) mode. Our research shows, however, that a combination of cos(2(omega)t) and steady flow should lead to efficient separation free of end effects. This possibility is currently under investigation

Cloud-Chamber Observations of Some Unusual Neutral V Particles Having Light Secondaries

From six cloud-chamber photographs of unusual V0 decay events, the following conclusions are drawn: (1) there is a neutral V particle that decays into two particles lighter than κ mesons with a Q value too small to be consistent with a θ0(π, π, 214 Mev) particle; (2) some of these events cannot be explained in terms of the decay of a τ0(π0, π-, π+, Q∼80 Mev) particle; (3) these events can be explained by any one of a number of three-body decay schemes, but two different types of V particles must be postulated if two-body decays are assumed

Cloud-Chamber Study of Charged V Particles

An analysis of 103 charged V-particle decays is presented. These events have been observed with a double cloud chamber operated at 1750-m altitude. The events in the upper chamber appear to have markedly different properties from those in the lower. The particles in the upper chamber have measured properties which are in every respect consistent with those of the κ meson. Their lifetime is in the range 5×10^-10 to 2×10^-8 sec; their mass is ∼1000 me; their transverse momentum distribution is consistent with a three-body decay scheme; the momentum in the center-of-mass system of their charged decay products is also consistent with three-body decay; and their frequency of production is greater than 0.4 percent of the total number of shower particles observed. On the other hand, the particles observed in the lower chamber have a lifetime in the range 10^-11 to 3×10^-10 sec; their transverse momentum distribution is consistent with a two-body decay scheme; their frequency of production is greater than 0.8 percent of the total number of shower particles; they are observed with approximately one-third of the frequency of Λ0 particles; and they apparently can be produced in meson-nucleon collisions. The majority of the particles in the lower chamber are tentatively identified as charged hyperons with the aid of two cases which appear to have proton secondaries. The proposed decay scheme is V1+→p+π0+Q; and in order to fit all of the data, the alternate mode of decay, V1+→π++n+Q must be introduced. The Q value is estimated to be ≲125 Mev