A numerical model for predicting energy dispersion in thermal plumes issuing from large, vertical outfalls in shallow coastal water

A theoretical study of the heat and momentum transfer resulting from a flow of power plant condenser effluent discharged vertically to shallow, quiescent coastal receiving water is presented. The complete partial differential equations governing steady, incompressible, turbulent flow driven by both initial momentum and buoyancy are solved using finite-difference techniques to obtain temperature and velocity distributions in the near field of the thermal discharge. The method of steady-flow vorticity transport was deemed the most attractive approach for this numerical study. A partial differential equation for buoyancy transport was used as a direct couple to the vorticity transport equation, and related the effluent temperature and salinity to buoyancy through an equation of state for sea water. Three-dimensional formulations along with two-dimensional translent methods were investigated at the outset of this research. However, in view of excessive computation requirements, two-dimensional steady flow techniques were found to be satisfactory and computationally more attractive to meet objectives of this study. Turbulent quantities were treated through the use of Reynolds stresses with further simplification utilizing the concept of eddy diffusivities computed by Prandtl's mixing length theory. A Richardson number correlation was used to account for the effects of density gradients on the computed diffusivities. Results were obtained for over 100 cases, 66 of which are reported, using the computer program presented in this manuscript. These results ranged from cases of pure buoyancy to pure momentum and for receiving water depths from 1 to 80 discharge diameters deep. Various computed gross aspects of the flow were compared to published data and found to be in excellent agreement. Data for shallow water plumes and the ensuing lateral spread are not readily available; however, one computed surface temperature distribution was compared to proprietary data and found also to be in excellent agreement. It is concluded that the numerical techniques presented in this study comprise an accurate and practical method for thermal analysis of the type of discharge cited. Although Prandtl's theory was used in this study with good success, it was found that modeling eddy transport coefficients is an area of considerable weakness and research is needed for general numerical fluid dynamic applications

Characterization of a molecular switch system that regulates gene expression in mammalian cells through a small molecule

Abstract Background Molecular switch systems that activate gene expression by a small molecule are effective technologies that are widely used in applied biological research. Nuclear receptors are valuable candidates for these regulation systems due to their functional role as ligand activated transcription factors. Previously, our group engineered a variant of the retinoid × receptor to be responsive to the synthetic compound, LG335, but not responsive to its natural ligand, 9-cis-retinoic acid. Results This work focuses on characterizing a molecular switch system that quantitatively controls transgene expression. This system is composed of an orthogonal ligand/nuclear receptor pair, LG335 and GRQCIMFI, along with an artificial promoter controlling expression of a target transgene. GRQCIMFI is composed of the fusion of the DNA binding domain of the yeast transcription factor, Gal4, and a retinoid × receptor variant. The variant consists of the following mutations: Q275C, I310M, and F313I in the ligand binding domain. When introduced into mammalian cell culture, the switch shows luciferase activity at concentrations as low as 100 nM of LG335 with a 6.3 ± 1.7-fold induction ratio. The developed one-component system activates transgene expression when introduced transiently or virally. Conclusions We have successfully shown that this system can induce tightly controlled transgene expression and can be used for transient transfections or retroviral transductions in mammalian cell culture. Further characterization is needed for gene therapy applications.</p

Patterns of Distribution of Oxygen-Binding Globins, Neuroglobin and Cytoglobin in Human Retina

Objective To determine the distribution of 2 intracellular oxygen-carrying molecules, neuroglobin (NGB) and cytoglobin (CYGB), in specific retinal cell types of human retinas. Methods Specific antibodies against NGB and CYGB were used in immunohistochemical studies to examine their distribution patterns in human retinal sections. Double-labeling studies were performed with the anti-NGB and anti-CYGB antibodies along with antibodies against neuronal (microtubule-associated protein 2, class III β-tubulin [TUJ1], protein kinase C alpha, calretinin) and glial (vimentin, glial fibrillary acid protein) markers. Confocal microscopy was used to examine the retinal sections. Results Immunohistochemical analysis of human retinal tissue showed NGB and CYGB immunoreactivity in the ganglion cell layer, inner nuclear layer, inner and outer plexiform layers, and retinal pigment epithelium. Neuroglobin immunoreactivity was also present in the outer nuclear layer and photoreceptor inner segments. Neuroglobin and CYGB were coexpressed in the neurons in the ganglion cell layer and inner nuclear layer but not within glial cells. Conclusion Neuroglobin and CYGB are colocalized within human retinal neurons and retinal pigment epithelium but not within glial cells. Clinical Relevance Our results suggest that NGB and CYGB may serve a neuroprotective role as scavengers of reactive oxygen species and therefore should be considered when developing therapeutic strategies for treatment of hypoxia-related ocular diseases

PIKES Analysis Reveals Response to Degraders and Key Regulatory Mechanisms of the CRL4 Network

Co-opting Cullin4 RING ubiquitin ligases (CRL4s) to inducibly degrade pathogenic proteins is emerging as a promising therapeutic strategy. Despite intense efforts to rationally design degrader molecules that co-opt CRL4s, much about the organization and regulation of these ligases remains elusive. Here, we establish protein interaction kinetics and estimation of stoichiometries (PIKES) analysis, a systematic proteomic profiling platform that integrates cellular engineering, affinity purification, chemical stabilization, and quantitative mass spectrometry to investigate the dynamics of interchangeable multiprotein complexes. Using PIKES, we show that ligase assemblies of Cullin4 with individual substrate receptors differ in abundance by up to 200-fold and that Cand1/2 act as substrate receptor exchange factors. Furthermore, degrader molecules can induce the assembly of their cognate CRL4, and higher expression of the associated substrate receptor enhances degrader potency. Beyond the CRL4 network, we show how PIKES can reveal systems level biochemistry for cellular protein networks important to drug development

Science of entropy-stabilized ultra-high temperature thin films: Synthesis, validation and properties

The authors report on using multi-cathode magnetron sputtering to fabricate 5-component refractory carbides that are stabilized by configurational entropy to form a robust and high-temperature class of high temperature materials. Magnetron sputtering is an appealing fabrication method as one can prepare layers with high density and the compositional flexibility afforded by five independent metallic sources. Thin layers that comprise mixed carbides of the following elements: W, Mo, Ti, Hf, Zr, Ta, V, and Nb, will be discussed. In all cases sputtering is performed reactively in a gas atmosphere including Ar as the inert sputter gas and propane as the carbon source. Sputter depositions can be conducted between room temperature and 800 °C. The relationship between sputtering parameters including power, pressure, rate, gas mixture, and film properties including density, thermal conductivity, lattice constant, and phase evolution will be discussed. Please click Additional Files below to see the full abstract

S-102 Transfer Pump Restriction Modeling Results

It was determined that a radioactive waste leak in the Hanford S Farm in the vicinity of the S-102 retrieval pump discharge occurred because of over-pressurization and failure of the S-102 dilution water supply hose while operating the retrieval pump in reverse with an obstructed suction cavity and an unobstructed flow path to the dilution water supply hose. This report describes efforts to identify plausible scenarios for the waste leak to occur

Science of high entropy ultra-high temperature thin films: synthesis and characterization

The authors describe the use of a 5-cathode reactive RF magnetron sputtering system to fabricate up to 5-component refractory high entropy carbides which form a robust class of high temperature materials. Magnetron sputtering is an appealing fabrication method it allows for deposition of high density films of many compositions at relatively low temperatures compared to bulk processing techniques. Thin films of mixed carbides consisting of the following elements: Ti, Zr, Hf, Nb, Ta, Mo, and W, will be discussed. All films are sputtered reactively in a gas atmosphere where Ar is the inert sputter gas with methane as the carbon source. Carbon stoichiometry is controlled via methane flow rates and assessed with density measurements. Use of 5 cathodes allows for rapid exploration of the 5 metal composition space from unary to quaternary or quinary carbides in short time spans. Please click Additional Files below to see the full abstract

Measurements and simulations of the phonon thermal conductivity of entropy stabilized alloys

The phonon thermal conductivity of solids is intimately related to any changes in atomic scale periodicity. As a classic example, the phonon thermal conductivity of alloys can be greatly reduces as compared to that of the corresponding non-alloy parent materials. However, the improved mechanical properties and environmental stability of alloyed materials makes these multi-atom solids ideal for a wide variety of applications. In this sense, entropy stabilized oxides and high entropy diborides are promising new materials that have potential to withstand extreme environments consisting of high temperatures and pressures. In these novel materials, thermal characterization is essential for understanding and predicting performance at elevated temperatures, as the presence of multi atomic species (5+ different atoms) in these solid solutions could lead to drastically modified phonon scattering rates and thermal conductivities. In this talk, we present recent measurements and molecular dynamics simulations on multiple atom alloys, including entropy stabilized oxides and high entropy diborides. We use time-domain thermoreflectance (TDTR), and optical pump-probe technique, to measure the thermal conductivity of these various systems. We also demonstrate the ability to extend TDTR measurements to temperatures above 1000 deg. C. The TDTR measurements show drastic reductions in the thermal conductivity of these crystalline solid solution materials, approaching values of the amorphous phases. These reductions in thermal conductivity can not be explained by phonon-mass scattering alone. Thus, to investigate the nature of the reduction in thermal conductivity of these multi-atom solid solutions, we turn to classical molecular dynamics simulations. In agreement with the Klemens’ perturbation theory, the thermal conductivity reduction due to mass scattering alone is found to reach a critical point, whereby adding more impurity atoms in the solid solution does not reduce the thermal conductivity. A further decrease in thermal conductivity requires a change in local strain-field, which together with mass defect scattering can lead to ultralow thermal conductivities in solid solutions, which surpasses the theoretical minimum limit of the corresponding amorphous phases. These simulations qualitatively agree well with our experimental measurements, and add insight into the nature of phonon scattering in entropy stabilized materials. This work is supported by the U.S. Office of Naval Research MURI program (grant No. N00014-15-1-2863)

Phonon scattering mechanisms contributing to the low thermal conductivities of entropy stabilized oxides and high entropy carbides

The phonon thermal conductivity of solids is intimately related to any changes in atomic scale periodicity. As a classic example, the phonon thermal conductivity of alloys can be greatly reduced as compared to that of the corresponding non-alloy parent materials. However, the improved mechanical properties and environmental stability of alloyed materials makes these multi-atom solids ideal for a wide variety of applications. In this sense, entropy stabilized oxides and high entropy carbides are promising new materials that have potential to withstand extreme environments consisting of high temperatures and pressures. In these novel materials, thermal characterization is essential for understanding and predicting performance at elevated temperatures, as the presence of multi atomic species (5+ different atoms) in these solid solutions could lead to drastically modified phonon scattering rates and thermal conductivities. In this talk, we present recent measurements and molecular dynamics simulations on multiple atom alloys, including entropy stabilized oxides and high entropy diborides. We use time-domain thermoreflectance (TDTR), and optical pump-probe technique, to measure the thermal conductivity of these various systems. We also demonstrate the ability to extend TDTR measurements to temperatures above 1000 deg. C. The TDTR measurements show drastic reductions in the thermal conductivity of these crystalline solid solution materials, approaching values of the amorphous phases. These reductions in thermal conductivity can not be explained by phonon-mass scattering alone. Thus, to investigate the nature of the reduction in thermal conductivity of these multi-atom solid solutions, we turn to classical molecular dynamics simulations. In agreement with the Klemens’ perturbation theory, the thermal conductivity reduction due to mass scattering alone is found to reach a critical point, whereby adding more impurity atoms in the solid solution does not reduce the thermal conductivity. A further decrease in thermal conductivity requires a change in local strain-field, which together with mass defect scattering can lead to ultralow thermal conductivities in solid solutions, which surpasses the theoretical minimum limit of the corresponding amorphous phases. These simulations qualitatively agree well with our experimental measurements, and add insight into the nature of phonon scattering in entropy stabilized materials. This work is supported by the U.S. Office of Naval Research MURI program (grant No. N00014-15-1-2863