Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry

Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated

Analysis of two-body decays of charmed baryons using the quark-diagram scheme

We give a general formulation of the quark diagram scheme for the nonleptonic weak decays of baryons. We apply it to all decays of the antitriplet and sextet charmed baryons and express their decay amplitudes in terms of the quark-diagram amplitudes, including the effects of final-state interactions. (We also point out the mistaken results in the literature.) We obtain many relations among various decay modes. It will be interesting to test them in future experiments

Salient collinear grouping diminishes local salience in visual search: An eye movement study

SCI Impact Factor(2011)=2.417[[abstract]]Our eyes and attention are easily attracted to salient items in search displays. When a target is spatially overlapped with a salient distractor (overlapping target), it is usually detected more easily than when it is not (nonoverlapping target). Jingling and Tseng (2013), however, found that a salient distractor impaired visual search when the distractor was comprised of more than nine bars collinearly aligned to each other. In this study, we examined whether this search impairment is due to reduction of salience on overlapping targets. We used the short-latency saccades as an index for perceptual salience. Results showed that a long collinear distractor decreases perceptual salience of local overlapping targets in comparison to nonoverlapping targets, reflected by a smaller proportion of the short-latency saccades. Meanwhile, a salient noncollinear distractor increases salience of overlapping targets. Our results led us to conclude that a long collinear distractor diminishes the perceptual salience of the target, a factor which poses a counter-intuitive condition in which a target on a salient region becomes less salient. We discuss the possible causes for our findings, including crowding, the global precedence effect, and the filling-in of a collinear contour.[[notice]]補正完畢[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]電子版[[countrycodes]]US

The System Si 3 N 4 -SiO 2 -Y 2 O 3

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65627/1/j.1151-2916.1980.tb10644.x.pd

Laser pulse annealing of ion-implanted GaAs

GaAs single-crystals wafers are implanted at room temperature with 400-keV Te + ions to a dose of 1×10^15 cm^–2 to form an amorphous surface layer. The recrystallization of this layer is investigated by backscattering spectrometry and transmission electron microscopy after transient annealing by Q-switched ruby laser irradiation. An energy density threshold of about 1.0 J/cm^2 exists above which the layer regrows epitaxially. Below the threshold the layer is polycrystalline; the grain size increases as the energy density approaches threshold. The results are analogous to those reported for the elemental semiconductors, Si and Ge. The threshold value observed is in good agreement with that predicted by the simple model successfully applied previously to Si and Ge

Biosynthesis of chiral 3-hydroxyvalerate from single propionate-unrelated carbon sources in metabolically engineered E. coli

Background The ability to synthesize chiral building block molecules with high optical purity is of considerable importance to the fine chemical and pharmaceutical industries. Production of one such compound, 3-hydroxyvalerate (3HV), has previously been studied with respect to the in vivo or in vitro enzymatic depolymerization of biologically-derived co-polymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). However, production of this biopolymeric precursor typically necessitates the supplementation of a secondary carbon source (e.g., propionate) into the culture medium. In addition, previous approaches for producing 3HV have not focused on its enantiopure synthesis, and thus suffer from increased costs for product purification. Results Here, we report the selective biosynthesis of each 3HV stereoisomer from a single, renewable carbon source using synthetic metabolic pathways in recombinant strains of Escherichia coli. The product chirality was controlled by utilizing two reductases of opposing stereoselectivity. Improvement of the biosynthetic pathway activity and host background was carried out to elevate both the 3HV titers and 3HV/3HB ratios. Overall, shake-flask titers as high as 0.31 g/L and 0.50 g/L of (S)-3HV and (R)-3HV, respectively, were achieved in glucose-fed cultures, whereas glycerol-fed cultures yielded up to 0.19 g/L and 0.96 g/L of (S)-3HV and (R)-3HV, respectively. Conclusions Our work represents the first report of direct microbial production of enantiomerically pure 3HV from a single carbon source. Continued engineering of host strains and pathway enzymes will ultimately lead to more economical production of chiral 3HV.Synthetic Biology Engineering Research CenterNational Science Foundation (Grant EEC-0540879)Massachusetts Institute of Technology. Energy InitiativeShell Oil Compan