583 research outputs found
Stereoelectronic control of photophysics:red and yellow axial and equatorial anomers of a rhenium-quinoline complex
A novel quinoline-substituted pyrimidine ligand forms two different coloured complexes upon reaction with Re(CO)(5)Br. These compounds display distinct photophysical properties that are dictated by their stereochemistry
Computational Fluid Dynamic Simulations for Determination of Ventricular Workload in Aortic Arch Obstructions
Objective
The cardiac workload associated with various types of aortic obstruction was determined using computational fluid dynamic simulations. Methods
Computed tomography image data were collected from 4 patients with 4 distinct types of aortic arch obstructions and 4 controls. The categorization of arch hypoplasia corresponded to the “A, B, C” nomenclature of arch interruption; a type “D” was added to represent diffuse arch hypoplasia. Measurements of the vessel diameter were compared against the normal measurements to determine the degree of narrowing. Three-dimensional models were created for each patient, and additional models were created for type A and B hypoplasia to represent 25%, 50%, and 75% diameter narrowing. The boundary conditions for the computational simulations were chosen to achieve realistic flow and pressures in the control cases. The simulations were then repeated after changing the boundary conditions to represent a range of cardiac and vascular adaptations. The resulting cardiac workload was compared with the control cases. Results
Of the 4 patients investigated, 1 had aortic coarctation and 3 had aortic hypoplasia. The cardiac workload of the patients with 25% narrowing type A and B hypoplasia was not appreciably different from that of the control. When comparing the different arch obstructions, 75% type A, 50% type B, and 50% type D hypoplasia required a greater workload increase than 75% coarctation. Conclusions
The present study has determined the hemodynamic significance of aortic arch obstruction using computational simulations to calculate the cardiac workload. These results suggest that all types of hypoplasia pose more of a workload challenge than coarctation with an equivalent degree of narrowing
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Advanced oxidation and reduction processes: Closed-loop applications for mixed waste
At Los Alamos we are engaged in applying innovative oxidation and reduction technologies to the destruction of hazardous organics. Non thermal plasmas and relativistic electron-beams both involve the generation of free radicals and are applicable to a wide variety of mixed waste as closed-loop designs can be easily engineered. Silent discharge plasmas (SDP), long used for the generation of ozone, have been demonstrated in the laboratory to be effective in destroying hazardous organic compounds and offer an altemative to existing post-incineration and off-gas treatments. SDP generates very energetic electrons which efficiently create reactive free radicals, without adding the enthalpy associated with very high gas temperatures. A SDP cell has been used as a second stage to a LANL designed, packed-bed reactor (PBR) and has demonstrated DREs as high as 99.9999% for a variety of combustible liquid and gas-based waste streams containing scintillation fluids, nitrates, PCB surrogates, and both chlorinated and fluorinated solvents. Radiolytic treatment of waste using electron-beams and/or bremsstrahlung can be applied to a wide range of waste media (liquids, sludges, and solids). The efficacy and economy of these systems has been demonstrated for aqueous waste through both laboratory and pilot scale studies. We win present recent experimental and theoretical results for systems using stand alone SDP, combined PBR/SDP, and electron-beam treatment methods
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Advanced oxidation and reduction processes: Closed-loop applications for mixed waste
At Los Alamos we are engaged in applying innovative oxidation and reduction technologies to the destruction of hazardous organics. Non thermal plasmas and relativistic electron-beams both involve the generation of free radicals and are applicable to a wide variety of mixed waste as closed-loop designs can be easily engineered. Silent discharge plasmas (SDP), long used for the generation of ozone, have been demonstrated in the laboratory to be effective in destroying hazardous organic compounds and offer an altemative to existing post-incineration and off-gas treatments. SDP generates very energetic electrons which efficiently create reactive free radicals, without adding the enthalpy associated with very high gas temperatures. A SDP cell has been used as a second stage to a LANL designed, packed-bed reactor (PBR) and has demonstrated DREs as high as 99.9999% for a variety of combustible liquid and gas-based waste streams containing scintillation fluids, nitrates, PCB surrogates, and both chlorinated and fluorinated solvents. Radiolytic treatment of waste using electron-beams and/or bremsstrahlung can be applied to a wide range of waste media (liquids, sludges, and solids). The efficacy and economy of these systems has been demonstrated for aqueous waste through both laboratory and pilot scale studies. We win present recent experimental and theoretical results for systems using stand alone SDP, combined PBR/SDP, and electron-beam treatment methods
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Advanced oxidation technologies for chemical demilitarization
This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. The main project objective was to establish a technical basis for future program development in the area of chemical warfare agent destruction using a Los Alamos-developed advanced oxidation process: a two-stage device consisting of thermal packed-bed reactor (PBR) and a nonthermal plasma (NTP) reactor. Various compounds were evaluated as potential surrogates for chemical warfare (CW) agents. Representative effluent mass balances were projected for future comparisons with incinerators. The design and construction of lab-scale PBR/NTP reactors (consisting of a liquid injection and metering system, electric furnace, condensers, chemical traps, plasma reactors, power supplies, and chemical diagnostics) has been completed. This equipment, the experience gained from chemical-processing experiments, process modeling, and an initial demonstration of the feasibility of closed-loop operation, have provided a technical basis for further demonstrations and program development efforts
Unprecedented staining of polar lipids by a luminescent rhenium complex revealed by FTIR microspectroscopy in adipocytes.
Fourier transform infrared (FTIR) microspectroscopy and confocal imaging have been used to demonstrate that the neutral rhenium(i) tricarbonyl 1,10-phenanthroline complex bound to 4-cyanophenyltetrazolate as the ancillary ligand is able to localise in regions with high concentrations of polar lipids such as phosphatidylethanolamine (PE), sphingomyelin, sphingosphine and lysophosphatidic acid (LPA) in mammalian adipocytes
Non-state space: The strategic ejection of dangerous and high maintenance urban space
Some commentators have characterised so-called ‘no-go’ areas as sites in which the
exercise of authority is prevented. Here we suggest that many such spaces are produced by
state, policing and citizen repertoires that aim to minimise the costs and risks of engaging,
supporting and servicing such spaces and their populations. In this article we locate
strategies of public spending, policing and political action that offer a governing logic in
which neighbourhoods are essentially subtracted from the constitution of the city. During
such designations the assurances of citizenship, vitality of civic institutions and presence of
policing may be partially or wholly suspended. We present a framework for the
identification of such strategies in which these forms of social, political and spatial exiting
are described as being autotomic in nature – spaces that are ejected in order to avoid losses
or further damage to the body politic of the city in ways akin to the response of certain
animals that protect themselves from predation by shedding a limb or body part. This term
adds force and depth to assessments of the ways in which both temporary and more
sustained exits by policing, management and state servicing are designed in order to avoid
responsibility over, or engagement with, spaces that are deemed a threat in order to
maintain the integrity of the remaining, included city
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