Browsing by Subject "transfer"
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Item Assembly Of The First Dwarf Galaxies(2010-11) Pawlik, A.; Milosavljevic, M.; Bromm, V.; Pawlik, Andreas; Milosavljević, Miloš; Bromm, VolkerUnderstanding the formation and evolution of the first stars and galaxies is crucial to understanding reionization, a key epoch in the history of the Universe. Detailed theoretical studies of the galaxies before and during reionization are now particularly urgent because of the wealth of observational data that will soon be provided by the next generation of telescopes, such as JWST, ALMA, LOFAR, MWA, and others. We simulate the formation of the first galaxies using cosmological smoothed particle hydrodynamics simulations. Zooming in on individual galaxies, we explore how various physical processes affect their assembly and further evolution. A highlight of our study will be the simulation of the radiation-hydrodynamics of galaxy assembly, which we will perform using our multi-frequency radiative transfer method TRAPHIC. Feedback from radiation has long been suspected to play a decisive role in galaxy formation and we will investigate its implications for observable properties of the first galaxies.Item Biomaterial-based ligand presentation to induce notch signaling in vitro(2013) Mehta, Naveen; Roy, KrishnenduT cell adoptive transfer is an important procedure in immunotherapy. In immunocompromised patients, T cells may need to be developed from stem cells, requiring the induction of Notch signaling events responsible for native T cell differentiation in the thymus. Current methods to develop T cells in vitro fail to mimic the 3D thymic niche and are not mechanically tunable. In this study, we improve on these approaches with a 2D polymer system with controllable mechanical properties, and with a 3D system that more accurately mimics the thymic niche. 3D inverse opal poly(ethylene glycol) (PEGDA) scaffolds were fabricated with defined pores using poly(methyl methacrylate) microspheres that are soluble in acetic acid, leaving negative space for cell growth. The PEGDA surface was made bioactive via biotinylation, followed by a streptavidin linker attaching biotinylated Notch ligand Delta-Like Ligand 4 (bDLL4). 2D polyacrylamide gels were prepared by sandwiching a pre-polymer droplet between two glass surfaces during redox initiation. Mechanical properties were modified by adjusting the concentrations of acrylamide and bisacrylamide. Gels were functionalized by immobilizing streptavidin via a SANPAH linker and binding bDLL4. After fabricating the systems and demonstrating their chemical and mechanical tunability, RT-PCR was used to detect Hes-1 expression, a downstream target of Notch, and flow cytometry was used to detect T cell differentiation levels following incubation of T cell progenitors with functionalized polymer systems. We show that a) the thymic niche can be effectively mimicked by synthetic systems, b) these systems effectively induce Notch signaling, and c) Notch signaling results in early T cell differentiation. These data are promising and suggest the potential to develop T cell banks from stem cells for the purposes of immunotherapy.Item Bursting and spalling in pretensioned U-beams(2009-12) Dunkman, David Andrew; Bayrak, Oguzhan, 1969-; Jirsa, James O.An experimental program was conducted at the Ferguson Structural Engineering Laboratory of The University of Texas at Austin, under the auspices of Texas Department of Transportation (TxDOT) Research Project 5831, to investigate the tensile stresses that develop in the end regions of pretensioned concrete U-beams at transfer of prestress. Understanding the effect of these “bursting” and “spalling” stresses is essential in order to design standard details that might lead to reliably-serviceable end regions. Two full-scale beam specimens, designed to be worst-case scenarios for bursting and spalling, were fabricated. Each beam had one square and one highly skewed end. Extensive instrumentation, including strain gages on transverse and lateral reinforcing bars, was employed in the end regions of these U-beams. Experimentally determined bursting and spalling stresses in these bars were compared to results of past projects (from the literature) investigating I-beams and inverted T-beams. Preliminary recommendations are made for changes in the standard reinforcing details for U-beam end regions. Such recommended details will be tested in the upcoming phase of Research Project 5831.Item Letter to Henryk Stenzel from Raymond C. Moore on 1967-01-19(1967-01-19) Moore, Raymond C.Item The LIBERATOR Archive, October 2018(University of Texas at Austin, 2018-10) University of Texas at AustinItem A Parameter Study Of The Dust And Gas Temperature In A Field Of Young Stars(2009-06) Urban, Andrea; Evans, Neal J.; Doty, Steven D.; Urban, Andrea; Evans, Neal J.We model the thermal effect of young stars on their surrounding environment in order to understand clustered star formation. We take radiative heating of dust, dust-gas collisional heating, cosmic-ray heating, and molecular cooling into account. Using DUSTY, a spherical continuum radiative transfer code, we model the dust temperature distribution around young stellar objects with various luminosities and surrounding gas and dust density distributions. We have created a grid of dust temperature models, based on our modeling with DUSTY, which we can use to calculate the dust temperature in a field of stars with various parameters. We then determine the gas temperature assuming energy balance. Our models can be used to make large-scale simulations of clustered star formation more realistic.Item Phase and Redox Shifted Four Iron/Four Sulfur Clusters: Fluorous Analogs of Metalloenzyme Cofactors(2015-07) Zhang, Cheng-Pan; Xi, Zhenxing; Mueller, Kory M.; Holliday, Bradley J.; Bazzi, Hassan S.; Gladysz, John A.; Mueller, Kory M.; Holliday, Bradley J.Reactions of (1) [Q](2)[Fe4S4(SC(CH3)(3))(4)] and the fluorous thiols HS(CH2)(n)R-f8 (n = 2, 3; R-f8 = (CF2)(7)CF3)), or (2) [Na](2)[Fe4S4(S(CH2)(n)R-f8)(4)] (n = 2, 3) and [PhCH2P((CH2)(3)R-f6)(3)][Br] or [PPN][Cl] (PPN = Ph3P - N - PPh3), give the title compounds [Q] 2[Fe4S4(S(CH2) nRf8) 4], comprised of a fluorous dianion and in some cases fluorous cations, with (1) Q/n = Ph4P/2 (4, 67%), Ph4P/3 (5, 67%), Me4N/3 (69%), and Ph3P(CH2)(2)R-f6/2 (73%) or (2) PhCH2P((CH2)(3)R-f6)(3)/2 (14, 39%), PhCH2P((CH2)(3)R-f6)(3)/3 (15, 63%), and PPN/2 (36%). The educt [Ph3P(CH2)(2)Rf(6)](2)[Fe4S4(SC(CH3)(3))(4)] is in turn prepared from FeCl3, HSC(CH3)(3)/CH3ONa, and [Ph3P( CH2)(2)R-f6][I], and the educts [Na](2)[Fe4S4(S(CH2) nR(f8))(4)] from [Na](2)[Fe4S4(SC(CH3)(3))(4)] and HS(CH2) nRf8. The SCH2 H-1 and C-13 NMR signals of these paramagnetic salts appear 8.7-10.3 and 32.3-34.9 ppm downfield from those of the corresponding thiols, but the chemical shifts of other signals are nearly normal. The UV-visible spectra show bands similar to those of non-fluorous analogs (290-298 nm and 406-415 nm; e = 25 700 and 19 200 M-1 cm-1 for 5). The singly fluorous salts are soluble in organic solvents of moderate polarity, but not in fluorous solvents. The doubly fluorous salts 14, 15 are soluble in all fluorous solvents assayed, with partition coefficients of > 99.65 : < 0.35 (CF3C6F11/toluene) and 93.2-93.1 : 6.9-6.8 (FC-72/THF). Cyclic voltammograms carried out using a platinum working microelectrode show that 4 is 0.08 V thermodynamically easier to reduce than 5.