Salt-gradient Solar Ponds: Summary of US Department of Energy Sponsored Research

The solar pond research program conducted by the United States Department of Energy was discontinued after 1983. This document summarizes the results of the program, reviews the state of the art, and identifies the remaining outstanding issues. Solar ponds is a generic term but, in the context of this report, the term solar pond refers specifically to saltgradient solar pond. Several small research solar ponds have been built and successfully tested. Procedures for filling the pond, maintaining the gradient, adjusting the zone boundaries, and extracting heat were developed. Theories and models were developed and verified. The major remaining unknowns or issues involve the physical behavior of large ponds; i.e., wind mixing of the surface, lateral range or reach of horizontally injected fluids, ground thermal losses, and gradient zone boundary erosion caused by pumping fluid for heat extraction. These issues cannot be scaled and must be studied in a large outdoor solar pond

Cofactor regeneration by a soluble pyridine nucleotide transhydrogenase for biological production of hydromorphone

We have applied the soluble pyridine nucleotide transhydrogenase of Pseudomonas fluorescens to a cell-free system for the regeneration of the nicotinamide cofactors NAD and NADP in the biological production of the important semisynthetic opiate drug hydromorphone. The original recombinant whole-cell system suffered from cofactor depletion resulting from the action of an NADP(+)-dependent morphine dehydrogenase and an NADH-dependent morphinone reductase. By applying a soluble pyridine nucleotide transhydrogenase, which can transfer reducing equivalents between NAD and NADP, we demonstrate with a cell-free system that efficient cofactor cycling in the presence of catalytic amounts of cofactors occurs, resulting in high yields of hydromorphone. The ratio of morphine dehydrogenase, morphinone reductase, and soluble pyridine nucleotide transhydrogenase is critical for diminishing the production of the unwanted by-product dihydromorphine and for optimum hydromorphone yields. Application of the soluble pyridine nucleotide transhydrogenase to the whole-cell system resulted in an improved biocatalyst with an extended lifetime. These results demonstrate the usefulness of the soluble pyridine nucleotide transhydrogenase and its wider application as a tool in metabolic engineering and biocatalysis

Duality Between the Weak and Strong Interaction Limits for Randomly Interacting Fermions

We establish the existence of a duality transformation for generic models of interacting fermions with two-body interactions. The eigenstates at weak and strong interaction U possess similar statistical properties when expressed in the U=0 and U=infinity eigenstates bases respectively. This implies the existence of a duality point U_d where the eigenstates have the same spreading in both bases. U_d is surrounded by an interval of finite width which is characterized by a non Lorentzian spreading of the strength function in both bases. Scaling arguments predict the survival of this intermediate regime as the number of particles is increased.Comment: RevTex4, 4 pages, 4 figures. Accepted for publication at Phys. Rev. Let

Evaluation of Aerodynamic and Propulsive Terminal Phase Systems for an Unmanned Mars Soft Lander

The terminal phase of an unmanned Mars soft lander is defined as that portion of the descent trajectory bridging the gap between the high speed entry trajectory and the very low speed soft landing. This paper presents the results of a parametric analysis comparing the performance and capability of several candidate deceleration systems considered for use during the terminal phase. System comparison is made on the basis of total decelerator system weight requirements and system capability to cope with the mission uncertainties. The mission mode is entry from orbit. Two general types of terminal phase decelerator systems are analyzed; aerodynamic and allretro systems. The aerodynamic decelerators considered include both subsonic type parachutes and (supersonic) ballutes. Subsonic type parachutes are limited to a maximum deployment Mach No. of 1.6. Supersonic ballutes are assumed deployed at Mach Nos. from 3.0 to 5.0. Both groups use a propulsive retro vernier system for final deceleration and landing. The all-retro system analysis assumes a rocket propulsion system with two phases - initial braking followed by a vertical descent

Dwarf Mistletoe Parasite in Spruce

Locations of all known major infection centers of dwarf mistletoe (Arceuthobium pusillum) in Minnesota are presented and compared to botanical ranges of important hosts. A brief summary of disease symptoms and identification of the parasite are included

Dynamics of Perfectly Wetting Drops under Gravity

We study the dynamics of small droplets of polydimethylsiloxane (PDMS) silicone oil on a vertical, perfectly-wetting, silicon wafer. Interference videomicroscopy allows us to capture the dynamics of these droplets. We use droplets with a volumes typically ranging from 100 to 500 nanolitres (viscosities from 10 to 1000 centistokes) to understand long time derivations from classical solutions. Past researchers used one dimensional theory to understand the typical $t^{1/3}$ scaling for the position of the tip of the droplet in time $t$. We observe this regime in experiment for intermediate times and discover a two-dimensional, similarity solution of the shape of the droplet. However, at long times our droplets start to move more slowly down the plane than the $t^{1/3}$ scaling suggests and we observe deviations in droplet shape from the similarity solution. We match experimental data with simulations to show these deviations are consistent with retarded van der Waals forcing which should become significant at the small heights observed

Drying and cracking mechanisms in a starch slurry

Starch-water slurries are commonly used to study fracture dynamics. Drying starch-cakes benefit from being simple, economical, and reproducible systems, and have been used to model desiccation fracture in soils, thin film fracture in paint, and columnar joints in lava. In this paper, the physical properties of starch-water mixtures are studied, and used to interpret and develop a multiphase transport model of drying. Starch-cakes are observed to have a nonlinear elastic modulus, and a desiccation strain that is comparable to that generated by their maximum achievable capillary pressure. It is shown that a large material porosity is divided between pore spaces between starch grains, and pores within starch grains. This division of pore space leads to two distinct drying regimes, controlled by liquid and vapor transport of water, respectively. The relatively unique ability for drying starch to generate columnar fracture patterns is shown to be linked to the unusually strong separation of these two transport mechanisms.Comment: 9 pages, 8 figures [revised in response to reviewer comments

Drying and cracking mechanisms in a starch slurry

Starch-water slurries are commonly used to study fracture dynamics. Drying starch-cakes benefit from being simple, economical, and reproducible systems, and have been used to model desiccation fracture in soils, thin film fracture in paint, and columnar joints in lava. In this paper, the physical properties of starch-water mixtures are studied, and used to interpret and develop a multiphase transport model of drying. Starch-cakes are observed to have a nonlinear elastic modulus, and a desiccation strain that is comparable to that generated by their maximum achievable capillary pressure. It is shown that a large material porosity is divided between pore spaces between starch grains, and pores within starch grains. This division of pore space leads to two distinct drying regimes, controlled by liquid and vapor transport of water, respectively. The relatively unique ability for drying starch to generate columnar fracture patterns is shown to be linked to the unusually strong separation of these two transport mechanisms.Comment: 9 pages, 8 figures [revised in response to reviewer comments

Special Theory of Relativity through the Doppler Effect

We present the special theory of relativity taking the Doppler effect as the starting point, and derive several of its main effects, such as time dilation, length contraction, addition of velocities, and the mass-energy relation, and assuming energy and momentum conservation, we discuss how to introduce the 4-momentum in a natural way. We also use the Doppler effect to explain the "twin paradox", and its version on a cylinder. As a by-product we discuss Bell's spaceship paradox, and the Lorentz transformation for arbitrary velocities in one dimension.Comment: 20 pages, 1 figur

Crushed Stone Aggregate Resources of Indiana

Indiana Geological Survey Bulletin 42-HMineral aggregate is an aggregation of mineral material, such as crushed rock, expanded shale, perlite, sand and gravel, shells, or slag. It is sometimes bound with such material as cement or asphalt or is sometimes not bound for use as filter stone, flux stone, railroad ballast, riprap, or road metal. Crushed limestone and dolomite, sand and gravel, slag, perlite, and expanded shale are the main natural and fabricated aggregates currently used in Indiana. Some aggregate, such as sand and gravel, requires little or no processing and can be used almost as it is mined, but rock must be crushed and sorted into various desired sizes before it can be used. Many types of rocks can be used for crushed stone aggregate, but limestone and dolomite are used exclusively in Indiana (pl. 1). In this report crushed stone is synonymous with crushed limestone and dolomite. Each type of aggregate has a distinct advantage with respect to cost and availability or to a specific use for which one type is more suited than another. The advantages of crushed limestone and dolomite are that they can be crushed and sized to meet most specifications, the materials are clean and angular and bind well with cementing mixtures, a uniform lithologic composition can be maintained with little or no selective quarrying in many areas, and they are available at low cost in most counties in Indiana. Crushed stone is one of Indiana’s most important mineral commodities, ranking third in annual value behind coal and cement. During 1969 crushed stone production in Indiana totaled 25, 516,000 tons and was valued at $34,418,000.Indiana Department of Natural Resource