PWR annulus thermal hydraulics important to analysis of pressurized thermal shock

Analysis of plume mixing in the annulus of a pressurized water reactor (PWR) are presented. The plume mixing analysis is based on a simple two-dimensional model that accounts for the surrounding flow and confinement. A correlation for entrainment is presented and comparison with experiment is made.Mixed convection resulting from downflow between parallel heated plates is studied experimentally. The experimental system used to obtain the data is described with the scaling rationale for choosing the working fluid. Heat transfer results are presented in terms of a Nusselt number and a correlation is given. Results show an enhancement in heat transfer with increasing Gr_Dh/Re_Dh² due to an increase in turbulence intensity associated with the buoyant wall layer. The correlation obtained for Gr_Dh/Re_Dh² < 2.29 was found to be Nu_Dh/Nu_Dh,0 = 1 + 2.93 (Gr_Dh/Re_Dh²)^0.54, where where Nu_Dh,0 is given by the Dittus-Boelter correlation. Use of this correlation for Gr_Dh/Re_Dh² > 2.29 is not recommended due to an observed flow bifurcation in this neighborhood.     

High hydrostatic pressure modification of whey protein concentrate for improved functional properties

Whey protein concentrate (WPC) has many applications in the food industry. Previous research demonstrated that treatment of whey proteins with high hydrostatic pressure (HHP) can enhance solubility and foaming properties of whey proteins. The objective of this study was to use HHP to improve functional properties of fresh WPC, compared with functional properties of reconstituted commercial whey protein concentrate 35 (WPC 35) powder. Fluid whey was ultrafiltered to concentrate proteins and reconstituted to equivalent total solids (8.23%) as reconstituted commercial WPC 35 powder. Solutions of WPC were treated with 300 and 400 MPa (0- and 15-min holding time) and 600 MPa (0-min holding time) pressure. After HHP, the solubility of the WPC was determined at both pH 4.6 and 7.0 using UDY and BioRad protein assay methods. Overrun and foam stability were determined after protein dispersions were whipped for 15 min. The protein solubility was greater at pH 7.0 than at pH 4.6, but there were no significant differences at different HHP treatment conditions. The maintenance of protein solubility after HHP indicates that HHP-treated WPC might be appropriate for applications to food systems. Untreated WPC exhibited the smallest overrun percentage, whereas the largest percentage for overrun and foam stability was obtained for WPC treated at 300 MPa for 15 min. Additionally, HHP-WPC treated at 300 MPa for 15 min acquired larger overrun than commercial WPC 35. The HHP treatment of 300 MPa for 0 min did not improve foam stability of WPC. However, WPC treated at 300 or 400 MPa for 15 min and 600 MPa for 0 min exhibited significantly greater foam stability than commercial WPC 35. The HHP treatment was beneficial to enhance overrun and foam stability of WPC, showing promise for ice cream and whipping cream applications.     

SETTING INTERNAL AUDIT’S LONG-TERM PRIORITIES

As I have discussed in past articles, internal audit efforts must be risk-based and contribute to the long-term assurance needs of the organization and its board. A formal risk-assessment audit must be completed at least annually and the results of that assessment should direct audit priorities. Periodic updates throughout the year are also highly recommended. Over time, a focus on short-term results (quarterly financial results, meeting current regulatory requirements, etc.) has driven the priorities of management and consequently the organization toward a short-term perspective. Similarly, internal auditing’s efforts has commonly moved toward this short-term focus, boiling down priorities to whichever audits the company needs to complete in the immediate quarter or two. During the challenging business environment period some would say it is not a good time to refocus sights on the long-term horizon. I disagree. For example, knowing what the organization want to achieve in the next two to five years, and what does it need to do to get there, is critical to success! Certainly, each organization will have different goals, objectives, issues, and challenges, and no single “standard” long-term internal audit plan will work; but I took a shot at it anyway, and present the results in this article.     

Particle flow and sintering processes in extrusion

The flow mechanism of particulate polymers during processing is reviewed. The extrusion of starch-g-poly(methyl acrylate) polymers is a good example of this type of processing, since graft copolymers retain their granular appearance and do not melt, even at high temperature, due to the rigid starch matrix. The formation of a continuous plastic by extrusion is accomplished by the sintering of heat-deformed granules in the high-pressure zone of the extruder die. Photomicrographs confirm this mode of formation. Plots of flow rate through the extruder die versus pressure in the die are presented. Tensile strengths and percent elongation of extruded specimens are not greatly affected by variations in flow rate. The equilibrium moisture content (about 5 percent) of starch-g-poly(methyl acrylate) plasticizes the starch component and thus reduces the operating pressure in the die. Tensile strengths, however, are unaffected by the presence of equilibrium moisture. Final traces of residual acid (resulting from initiator solution) are difficult to remove from starch-g-poly(methyl acrylate), and prolonged heating of the graft copolymer in the presence of this acid results in polymer degradation.     

Chromatic contrast sensitivity: the role of absolute threshold and gain constant in differences between the fovea and the periphery

A model of foveal achromatic and chromatic sensitivity [Vision Res. 36, 1597 (1996)] was extended to the peripheral visual field. Threshold-versus-illuminance functions were analyzed to determine effects of eccentricity on absolute thresholds and gain constants of chromatic and luminance mechanisms. The resulting peripheral model successfully predicted peripheral contrast sensitivity as a function of wavelength, for both white and 500-nm backgrounds. We conclude that the short-wavelength-sensitive cone opponent mechanism may mediate thresholds in Sloan's notch in the normal periphery and that interpretation of reduced chromatic sensitivity in the periphery requires an explicit model of how eccentricity affects both the gain constant and the absolute threshold.     

Concerted evolution in an egg receptor for a rapidly evolving abalone sperm protein

Gamete interactions during fertilization exhibit species specificity. In abalone, the sperm protein lysin species-specifically creates a hole in the egg envelope. Lysin evolves rapidly by positive Darwinian selection. Evolution of the egg receptor for lysin provides the selective pressure for lysin's divergence. The egg receptor for lysin is a tandemly repeated sequence that evolves by concerted evolution. Concerted evolution in the egg receptor could explain the rapid, adaptive evolution in sperm lysin and may provide an underlying molecular mechanism that gives rise to species-specific fertilization.     

Stability of interests and the predictive and concurrent validity of the 1981 Strong-Campbell Interest Inventory for college majors.

116 of the 162 Occupational scales of the 1981 revision of the Strong-Campbell Interest Inventory (SCII) were constructed with new criterion samples. This study (a) assessed the concurrent and predictive validity of the revised SCII and explored its usefulness for predicting college majors (Exp I) and (b) examined the differential effect of stable and unstable interests during college on the validity of the SCII (Exp II). Data were analyzed for 354 females and 261 males who completed the SCII as college freshmen; 81% were still enrolled in school at the time of this study. Results indicate that the revised SCII can be used to predict college majors, having concurrent and predictive validity comparable to previous forms of the SCII. It was slightly more predictive for females than for males. Findings also show that the majority of Ss had stable interests during their college careers. The revised SCII was significantly more predictive of college majors for Ss who were satisfied with their majors or who had stable interests than it was for those who were dissatisfied or had unstable interests. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)