Mass transfer in vertical liquid-solids flow of coarse particles

Wall-to-bed mass transfer in the hydraulic transport of spherical glass particles was studied. The experiments were performed by transporting spherical glass particles 1.20, 1.94 and 2.98 mm in diameter with water in a 25.4 mm I.D. tube. The mass transfer coefficients were determined by following rate of dissolution of a segment of the transport tube prepared from benzoic acid.In the runs in hydraulic transport, the Reynolds number of the tube varied between 1826 and 27597. The loading ratio (G_p/G_f) was between 0.026 and 0.474, and the fluid superficial velocity was between 0.267 · U_t and 4.904 · U_t, where U_t represents the single particle terminal velocity. For these ratios, the voidage ranged from 0.7123 to 0.9228.Also, wall-to-bed mass transfer in the single phase flow regime was studied. In the runs without particles, the Reynolds number of the tube varied between 122 and 39132. The data for the mass transfer factor (j_D) in single phase flow are correlated for turbulent flow regime, using the Chilton-Colburn's type equations, j_D = f(Re). Those investigations were conducted in aim to compare with results for wall-to-bed mass transfer in hydraulic transport.The data for wall-to-bed mass transfer (j_D) in hydraulic transport of spherical particles were correlated by treating the flowing fluid-particle suspension as a pseudofluid, by introducing a modified suspension-wall friction coefficient (f_w) and a modified Reynolds number (Re_m). The data for wall-to-bed mass transfer in the hydraulic transport of particles show that an analogy between mass and momentum transfer exists.     

Effects of growth rate, sex and slaughter weight on fat characteristics of pork bellies

A total of 119 Duroc × (Landrace × Yorkshire) commercial pigs were used to investigate the effect of growth rate (fast vs slow), sex (barrows vs gilts) and slaughter liveweight (107, 115 and 125 kg) on the fat characteristics of bellies. Backfat thickness increased with weight (P < 0.01). Fat firmness score was only affected by sex (P < 0.05), with gilts showing softer bellies than barrows. Fat from gilts and slow growing pigs showed a lower proportion of saturated fatty acids (SFA; P < 0.001 and P < 0.01, respectively), a higher proportion of linoleic fatty acid (C18:2 n-6; P < 0.01), a higher proportion of total polyunsaturated fatty acids (PUFA; P < 0.001 and P < 0.01, respectively), and an increased iodine value (P < 0.001). Consequently, the fat from these bellies had higher PUFA:SFA ratios (P < 0.001) and n-6:n-3 ratios (P < 0.01 and P < 0.001, respectively) than that from the bellies of barrows and fast growing pigs. The belly fat from barrows and fast growing pigs had higher stearic fatty acid (C18:0; P < 0.01) and SFA proportions (P < 0.001 and P < 0.01, respectively) than that from gilts and slow growing pigs. The belly fat from gilts and slow growing pigs would better meet the health requirements of consumers, but it is more prone to rancidity during storage leading to a potentially reduced bacon shelf-life.     

Protein Denaturation in Pork Longissimus Muscle of Different Quality Groups

Differential scanning calorimetry (DSC) was used to investigate the protein denaturation characteristics of pork muscles from four quality groups namely RFN (red, firm, and non-exudative), RSE (red, soft, and exudative), PFN (pale, firm, and non-exudative), and PSE (pale, soft, and exudative). The thermograms indicated three endothermic peaks between 45°C to 90°C, corresponding to denaturation of myosin (peak I), sarcoplasmic proteins (peak II), and actin (peak III). The myosin peak was much reduced in PSE samples, while the actin peak remained almost identical in all groups. RFN and RSE samples were found to have very similar protein denaturation characteristics and were not significantly different in their thermodynamic protein denaturation parameters. PFN samples showed similar myofibrilar protein denaturation but significantly different sarcoplasmic protein denaturation characteristics compared to normal (RFN) samples according to their DSC thermograms. Based on these findings, it was suggested that the pale color in PFN pork is linked to sarcoplasmic protein denaturation.     

Effect of calf feeding regimes and diet EDTA on physico-chemical characteristics of veal stored under modified atmospheres

Physico-chemical characteristics of veal from 30 calves allotted to five different rations with respect to iron bioavailability were evaluated at packaging and after 2 and 4 weeks of storage under both 100% CO(2) and 100% N(2). The five diets were 'Milk', 'Grain', 'Mix' (combination of Milk and Grain) and 'Mix + EDTA' and 'Grain + EDTA' where 15 mg EDTA were added per mg Fe in the feed concentrate. Diet EDTA was generally more influential on veal quality than storage treatments. The chelator caused an unexpected pH drop in veal stored four weeks irrespective of storage conditions (p ≤ 0.05). However, the colour, texture and flavour of meat from animals fed EDTA in the Grain- and Mix-ration was equivalent to that of Milk-fed veal (p ≤ 0.05). The EDTA treatments also improved the appearance of veal under anoxic atmospheres. Upon storage however, the chelator increased veal drip losses (p ≤ 0.05) and also cooking losses from Grain-fed calves (p ≤ 0.05). Packaging under CO(2) decreased pH (p ≤ 0.05) and increased drip losses (p ≤ 0.05) but did not alter other physico-chemical parameters. Dietary treatments had no effect on shear forces (p > 0.05) which decreased after two weeks in storage (p ≤ 0.05) independent of gas atmospheres. Overall, the quality characteristics of pale veal were obtained following addition of EDTA in Grain- and Mix-fed animals and were maintained in storage. This approach looks promising for the veal industry but warrants further research.     

Heat transfer and flow pattern in vertical liquid-solids flow

Wall-to-bed heat transfer in hydraulic transport of spherical glass particles of diameter 1.20, 1.94 and 2.98 mm and in single-phase flow regime was studied. Experiments were performed by transporting the spherical glass particles with water in a 25.4 mm I.D. copper tube equipped with a steam jacket.In the runs without particles, the tube Reynolds number varied between 2280 and 21,300, while in hydraulic transport runs, the tube Reynolds number varied between 3300 and 20,150. The loading ratio (G_p/G_f) was between 0.07 and 0.328, and the fluid superficial velocity was between 0.29·U_t and 2.86·U_t, where U_t represents the single particle terminal velocity. For these ratios, the voidage ranged from 0.715 to 0.895.The data for the heat transfer factor (j_H) in single-phase flow are correlated using a general form j_H=f(Re). The data for wall-to-bed heat transfer in the hydraulic transport of particles show that an analogy between heat and momentum transfer exists. The data were correlated by treating the flowing fluid-particle suspension as a pseudofluid, by introducing a modified suspension-wall friction coefficient (f_w) and a modified Reynolds number (Re_m).     

Use of support vector regression and numerically predicted cloudiness to forecast power output of a photovoltaic power plant in Kitakyushu,Japan

The development of a methodology to forecast accurately the power produced by photovoltaic systems can be an important tool for the dissemination and integration of such systems on the public electricity grids. Thus, the objective of this study was to forecast the power production of a 1‐MW photovoltaic power plant in Kitakyushu, Japan, using a new methodology based on support vector machines and on the use of several numerically predicted weather variables, including cloudiness. Hourly forecasts of the power produced for 1 year were carried out. Moreover, the effect of the use of numerically predicted cloudiness on the quality of the forecasts was also investigated. The forecasts of power production obtained with the proposed methodology had a root mean square error of 0.0948 MW h and a mean absolute error of 0.058 MW h. It was also found that the forecast and measured values of power production had a good level of correlation varying from 0.8 to 0.88 according to the season of the year. Finally, the use of numerically predicted cloudiness had an important role in the accuracy of the forecasts, and when cloudiness was not used, the root mean square error of the forecasts increased more than 32%, and the mean absolute error increased more than 42%. Copyright © 2011 John Wiley & Sons, Ltd.     

Isotopic signature and impact of car catalysts on the anthropogenic osmium budget

Higher osmium concentrations and lower 187Os/188Os ratios in sediments from urban areas have been linked to anthropogenic osmium sources. Automobile catalytic converters that use platinum group metals (PGM) are a potential source for this Os pollution. We present the first direct Os concentrations and isotopic measurements of catalytic converters for major automobile brands to test the assumption that car catalysts release Os with a distinct signature in the environment. The analysis of four new catalytic converters yields similar low 187Os/188Os ratios (0.1-0.2), suggesting a similar source for the PGM. The Os concentrations measured are in the ppt range (6-228 ppt). From our results, the osmium contribution of the car catalysts to the environment through attrition (wearing and grinding down of the catalyst by friction) is predicted to be low, <0.2 pg Os/m2/year in highly urbanized environment. We show that Os loss from catalysts as volatile OsO4 is important at car catalyst operating temperatures. Moreover, we estimate that car catalysts may be responsible for up to approximately 120 pg Os/m2 deposited per year in urban areas and that part of it may be exported to sedimentary sinks. Car catalytic converters are thus an important anthropogenic osmium source in densely populated areas. The NIST car catalyst standard (SRM-2557, made from recycled used catalysts) yields higher concentrations (up to 721 ppt Os) and a more radiogenic isotopic composition (approximately 0.38), perhaps indicative of Os contamination during its preparation.     

Ultra-shallow raised p+−n junctions formed by diffusion from selectively depositedIn-situ doped Si0.7Ge0.3

In this paper, a novel raised p⁺−n junction formation technique is presented. The technique makes use ofin- situ doped, selectively deposited Si_0.7Ge_0.3 as a solid diffusion source. In this study, the films were deposited in a tungsten halogen lamp heated cold-walled rapid thermal processor using SiCl₂H₂, GeH₄, and B₂H₆. The microstructure of the Si_0.7Ge_0.3 layer resembles that of a heavily defected epitaxial layer with a high density of misfit dislocations, micro-twins, and stacking faults. Conventional furnace annealing or rapid thermal annealing were used to drive the boron from thein- situ doped Si_0.7Ge_0.3 source into silicon to form ultra-shallow p⁺−n junctions. Segregation at the Si_0.7Ge_0.3/Si interface was observed resulting in an approximately 3:1 boron concentration discontinuity at the interface. Junction profiles as shallow as a few hundred angstroms were formed at a background concentration of 10¹⁷ cm⁻³.     

Functionality of high and low voltage electrically stimulated beef chilled under moderate and rapid chilling regimes

Chuck muscles from 24 beef carcasses electrically stimulated (ES) with either high or low voltage, or a combination of both, and submitted to conventional or rapid chilling regimes were used in a model system study (pH, salt-solubloe protein extraction, emulsifying capacity) and in frank-further fabrication and analysis (yield, color, texture). Glycolytic rates measured in the loin had no effects on the functional parameters or on the quality of frankfurters. The ultimate pH values of unstimulated carcasses remained higher than in any ES carcasses, and led to higher protein extraction (P ≤ 0·05). However, ES had no further influence on the emulsifying capacity or on frankfurter yield and quality parameters independently of the voltage used (P > 0·05). Chilling regimes had no influence on the functional parameters of the model system but slightly influenced the yield and chewiness of the frankfurters (P ≤ 0·05). Therefore, the use of any type of ES in combination with either conventional (Canadian) or more rapid chilling is unlikely to have commercial significance on the yield or quality of frankfurters.     

A Comparative Study on the Effect of Chemical,Microwave, and Pulsed Electric Pretreatments on Convective Drying and Quality of Raisins

In order to discourage the use of chemicals in raisin processing, the effect of microwave and pulsed electric field (PEF) pretreatments on the drying rate and other quality parameters like color, total soluble solids, bulk density, appearance, and market quality were compared with that of chemically pretreated raisins dried at 65°C. The untreated and pretreated samples had a statistically significant difference in drying rate (P < 0.05). The drying rate of chemically pretreated raisins was the highest when compared to others. The results showed that the PEF and microwave-treated samples had a significantly high Total Soluble Solids (TSS), along with good appearance and market quality.