Effects of Buoyancy on Laminar, Transitional, and Turbulent Gas Jet Diffusion Flames

Gas jet diffusion flames have been a subject of research for many years. However, a better understanding of the physical and chemical phenomena occurring in these flames is still needed, and, while the effects of gravity on the burning process have been observed, the basic mechanisms responsible for these changes have yet to be determined. The fundamental mechanisms that control the combustion process are in general coupled and quite complicated. These include mixing, radiation, kinetics, soot formation and disposition, inertia, diffusion, and viscous effects. In order to understand the mechanisms controlling a fire, laboratory-scale laminar and turbulent gas-jet diffusion flames have been extensively studied, which have provided important information in relation to the physico-chemical processes occurring in flames. However, turbulent flames are not fully understood and their understanding requires more fundamental studies of laminar diffusion flames in which the interplay of transport phenomena and chemical kinetics is more tractable. But even this basic, relatively simple flame is not completely characterized in relation to soot formation, radiation, diffusion, and kinetics. Therefore, gaining an understanding of laminar flames is essential to the understanding of turbulent flames, and particularly fires, in which the same basic phenomena occur. In order to improve and verify the theoretical models essential to the interpretation of data, the complexity and degree of coupling of the controlling mechanisms must be reduced. If gravity is isolated, the complication of buoyancy-induced convection would be removed from the problem. In addition, buoyant convection in normal gravity masks the effects of other controlling parameters on the flame. Therefore, the combination of normal-gravity and microgravity data would provide the information, both theoretical and experimental, to improve our understanding of diffusion flames in general, and the effects of gravity on the burning process in particular

EVALUATION OF NON H. PYLORI SPIRAL ORGANISMS IN HUMAN GASTRIC BIOPSIES BY USING PCR AND MICROSCOPIC METHODS IN IRAN (FIRST REPORT)

Introduction and Objectives: The Discovery of Helicobacter pylori in 1982 increased interest in the range of other spiral bacteria that had been seen in Stomach (Marshall & Warren 1984).The power of technologies such as the polymerase chain reaction (PCR) with genus specific primers revealed that many of these bacteria belong to the genus Helicobacter. These nonpylori helicobacters are increasingly being found in human clinical specimens. Non-pylori Helicobacters are Gram-negative, motile, long, tightly coiled, Spiral bacteria ,with three to eight coils, that cause of some gastric problems like gastritis, peptic ulceration and Mcosa-Associated Lymphoid Tissue (MALT) lynphoma in animals and humans. Materials and Methods: Samples taken during endoscopy were analyzed by rapid urease test, PCR and light microscope(Giemsa and Gram staining). In this study 270 samples were collected from Patients with gastric disorders. Presence of Helicobacters confirmed by a positive urease test and Helicobacter genus specific PCR method utilized. DNA was prepared from biopsies using the Qiamp tissue kit (QIAGEN Inc., Valencia, Calif.) and frozen at −20°C (like gastric samples/biopsies). DNA samples that PCR positive were amplified with 16SrRNA gene primers against Helicobacter species. Results: In gastric biopsy specimen's non-pylori helicobacter spp., have been observed. At the end of the study we found that 71% of urease tests, 0.37% of light microscopic studies (we observed some spiral gram negative bacteria with 2-7 coils) and 0.74% of PCR tests were positive. In analysis with PCR route 2 person (both of them were Male) were infected with H.heilmanniilike organisms( one of them kept a dog for 5 years as a pet).16S rRNA gene amplification was performed on 270 DNA samples and results were positive for H.heilmannii in two cases (275-bp), but negative for H.bizzozeronnii,H.felis and H. Salmonis

Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Combinatorial Geometry

Citation: Wilson JW, Slaba TC, Badavi FF, Reddell BD, and Bahadori AA 2015 Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Combinatorial Geometry NASA/TP-2015-218980 NASA Langley Research Center: Hampton, VA http://ntrs.nasa.gov/search.jsp?R=20160001628The 3DHZETRN code, with improved neutron and light ion (Z (is) less than 2) transport procedures, was recently developed and compared to Monte Carlo (MC) simulations using simplified spherical geometries. It was shown that 3DHZETRN agrees with the MC codes to the extent they agree with each other. In the present report, the 3DHZETRN code is extended to enable analysis in general combinatorial geometry. A more complex shielding structure with internal parts surrounding a tissue sphere is considered and compared against MC simulations. It is shown that even in the more complex geometry, 3DHZETRN agrees well with the MC codes and maintains a high degree of computational efficiency

Solar Proton Transport Within an ICRU Sphere Surrounded by a Complex Shield: Ray-trace Geometry

Citation: Slaba TC, Wilson JW, Badavi FF, Reddell BD, and Bahadori AA 2015 Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Ray-Trace Geometry NASA/TP-2015-218994 NASA Langley Research Center: Hampton, VA http://ntrs.nasa.gov/search.jsp?R=20160002213The computationally efficient HZETRN code has been used in recent trade studies for lunar and Martian exploration and is currently being used in the engineering development of the next generation of space vehicles, habitats, and extra vehicular activity equipment. A new version (3DHZETRN) capable of transporting High charge (Z) and Energy (HZE) and light ions (including neutrons) under space-like boundary conditions with enhanced neutron and light ion propagation is under development. In the present report, new algorithms for light ion and neutron propagation with well-defined convergence criteria in 3D objects is developed and tested against Monte Carlo simulations to verify the solution methodology. The code will be available through the software system, OLTARIS, for shield design and validation and provides a basis for personal computer software capable of space shield analysis and optimization

A 3DHZETRN Code in a Spherical Uniform Sphere with Monte Carlo Verification

Citation: Wilson JW, Slaba TC, Badavi FF, Reddell BD, and Bahadori AA 2014 A 3DHZETRN Code in a Spherical Uniform Sphere with Monte Carlo Verification NASA/TP-2014-218271 NASA Langley Research Center: Hampton, VA http://ntrs.nasa.gov/search.jsp?R=20140006706The computationally efficient HZETRN code has been used in recent trade studies for lunar and Martian exploration and is currently being used in the engineering development of the next generation of space vehicles, habitats, and extra vehicular activity equipment. A new version (3DHZETRN) capable of transporting High charge (Z) and Energy (HZE) and light ions (including neutrons) under space-like boundary conditions with enhanced neutron and light ion propagation is under development. In the present report, new algorithms for light ion and neutron propagation with well-defined convergence criteria in 3D objects is developed and tested against Monte Carlo simulations to verify the solution methodology. The code will be available through the software system, OLTARIS, for shield design and validation and provides a basis for personal computer software capable of space shield analysis and optimization

Targeting delivery of lipocalin 2-engineered mesenchymal stem cells to colon cancer in order to inhibit liver metastasis in nude mice

One of the major obstacles in cancer therapy is the lack of anticancer agent specificity to tumor tissues. The strategy of cell-based therapy is a promising therapeutic option for cancer treatment. The specific tumor-oriented migration of mesenchymal stem cells (MSCs) makes them a useful vehicle to deliver anticancer agents. In this study, we genetically manipulated bone marrow-derived mesenchymal stem cells with their lipocalin 2 (Lcn2) in order to inhibit liver metastasis of colon cancer in nude mice. Lcn2 was successfully overexpressed in transfected MSCs. The PCR results of SRY gene confirmed the presence of MSCs in cancer liver tissue. This study showed that Lcn2-engineered MSCs (MSC-Lcn2) not only inhibited liver metastasis of colon cancer but also downregulated the expression of vascular endothelial growth factor (VEGF) in the liver. Overall, MSCs by innate tropism toward cancer cells can deliver the therapeutic agent, Lcn2, and inhibit cancer metastasis. Hence, it could be a new modality for efficient targeted delivery of anticancer agent to liver metastasis. © 2015, International Society of Oncology and BioMarkers (ISOBM)

A Study of Neutron Leakage in Finite Objects

A computationally efficient 3DHZETRN code capable of simulating High charge (Z) and Energy (HZE) and light ions (including neutrons) under space-like boundary conditions with enhanced neutron and light ion propagation was recently developed for simple shielded objects. Monte Carlo (MC) benchmarks were used to verify the 3DHZETRN methodology in slab and spherical geometry, and it was shown that 3DHZETRN agrees with MC codes to the degree that various MC codes agree among themselves. One limitation in the verification process is that all of the codes (3DHZETRN and three MC codes) utilize different nuclear models/databases. In the present report, the new algorithm, with well-defined convergence criteria, is used to quantify the neutron leakage from simple geometries to provide means of verifying 3D effects and to provide guidance for further code development

3D Space Radiation Transport in a Shielded ICRU Tissue Sphere

A computationally efficient 3DHZETRN code capable of simulating High Charge (Z) and Energy (HZE) and light ions (including neutrons) under space-like boundary conditions with enhanced neutron and light ion propagation was recently developed for a simple homogeneous shield object. Monte Carlo benchmarks were used to verify the methodology in slab and spherical geometry, and the 3D corrections were shown to provide significant improvement over the straight-ahead approximation in some cases. In the present report, the new algorithms with well-defined convergence criteria are extended to inhomogeneous media within a shielded tissue slab and a shielded tissue sphere and tested against Monte Carlo simulation to verify the solution methods. The 3D corrections are again found to more accurately describe the neutron and light ion fluence spectra as compared to the straight-ahead approximation. These computationally efficient methods provide a basis for software capable of space shield analysis and optimization

Space Radiation Transport Code Development: 3DHZETRN

The space radiation transport code, HZETRN, has been used extensively for research, vehicle design optimization, risk analysis, and related applications. One of the simplifying features of the HZETRN transport formalism is the straight-ahead approximation, wherein all particles are assumed to travel along a common axis. This reduces the governing equation to one spatial dimension allowing enormous simplification and highly efficient computational procedures to be implemented. Despite the physical simplifications, the HZETRN code is widely used for space applications and has been found to agree well with fully 3D Monte Carlo simulations in many circumstances. Recent work has focused on the development of 3D transport corrections for neutrons and light ions (Z 14 directions. The improved code, 3DHZETRN, transports neutrons, light ions, and heavy ions under space-like boundary conditions through general geometry while maintaining a high degree of computational efficiency. A brief overview of the 3D transport formalism for neutrons and light ions is given, and extensive benchmarking results with the Monte Carlo codes Geant4, FLUKA, and PHITS are provided for a variety of boundary conditions and geometries. Improvements provided by the 3D corrections are made clear in the comparisons. Developments needed to connect 3DHZETRN to vehicle design and optimization studies will be discussed. Future theoretical development will relax the forward plus isotropic interaction assumption to more general angular dependence