Factors that affect the aggregation of rennet-altered casein micelles at low temperatures

The effects of temperature, CaCl₂ concentration, pH and ionic strength of milk on the aggregation of casein micelles in milk renneted at 15ºC were studied using particle size analysis determined by laser-light scattering. The rate of aggregation of rennet-altered casein micelles became significantly slower on reducing the temperature of renneting from 30 to 10ºC. At 15ºC, the rate of aggregation of rennet-altered casein micelles increased significantly on adding CaCl₂, on reducing the pH of renneted milk or on adding NaCl (up to 50 m m ). These results indicate that particle size analysis can be used successfully to study the aggregation of rennet-altered casein micelles.     

Effect of Hydrogenation on the Chemical Composition of Canola Oil

Canola oil was hydrogenated under selective and nonselective conditions with commercial nickel catalysts. The composition of the hydrogenated oils was characterized by iodine value, fatty acid composition, trans-isomer content and cis, cis-methylene interrupted (CCMI) polyunsaturated fatty acids. Selectivity ratios and hydrogenation rates were calculated. Selective conditions resulted in high levels of trans-isomers. Loss of CCMI fatty acids occurred in the early stages of the hydrogenation process. Hydrogenation rates were higher under selective than under nonselective conditions.     

Biaxial Fracture Studies of a Glass-Ceramic

Uniaxial and equibiaxial tensile strengths are reported for glass-ceramic specimens exhibiting strength isotropy. Uniaxial strengths were determined in both 3- and 4-point bend tests. Stressing rate was a controlled variable and the tests were conducted in both dry N₂ and water environments, to provide data for different conditions of slow crack growth. There was little or no difference between strengths in the 3- and 4-point bend tests, indicating the absence of a size effect. In comparable tests, the strength under equibiaxial tension was greater than under uniaxial tension. The biaxial strengthening became less pronounced with increased slow crack growth during testing. A maximum observed biaxial-to-uniaxial strength ratio of 1.21 resulted from ball-on-ring and uniaxial bend tests in dry N₂. These results are attributed to differences in flaw severity between biaxial and uniaxial stressing. The decreasing strength ratios can be explained by a change in configuration of critical flaws due to slow crack growth. Numerical calculations, using a simplified two-dimensional model of the strength-controlling flaw, supported this hypothesis. The calculations also indicate that the slow crack growth exponent is smaller for the biaxial tension mode of stressing than for the uniaxial mode.     

Thermal Modelling of a Natural Convection Solar Water Heating System with a Thermal Trap Collector

A mathematical model has been developed to study the performance of a solar water heating system with a thermal trap flat plate collector and in which the flow of water between the collector and the storage tank is maintained by natural convection. An expression has also been developed for the mass flow rate in terms of known parameters. The model yields exact expressions for the temperature of water in the storage tank as a function of time in terms of collector's parameters and the solar insolation. Numerical calculations have been performed to compare the performance of the hot water heating system with a thermal trap collector with the one with an ordinary flat plate collector.     

Profit function analysis of system with mixture of warm and cold standby

This paper deals with the profit function analysis of a single-server two-unit standby system with two modes of each unit normal (N) and total failure (F). Regarding the standby unit, an interconversion is made repeatedly after a random length of time from warm to cold and cold to warm. Upon failure of the operative unit, the standby unit, if it is warm, starts the operation instantaneously; otherwise the system goes down until the cold standby starts operation. System failure occurs when both units fail totally. Identifying the system at suitable regenerative instants, integral equations are set up and explicit expressions of interest to system designers are obtained to carry out the profit function analysis. The results of two particular cases are also derived.     

Metallurgical and mechanical characterization of mild steel-mild steel joint formed by microwave hybrid heating process

In this paper, mild steel–mild steel (MS-MS) joints fabricated through microwave hybrid heating (MHH) have been characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe micro analyser (EPMA), Vicker’s microhardness measurement and tensile strength. The XRD spectrum of the developed joints shows substitution type of solid solution form in the joint zone. The back scattered electron (BSE) images of the joint obtained by SEM show complete melting of powder particle and consequently diffusion bonding takes place between the substrate and the powder particle. The electron probe micro analysis shows diffusion of element across the joint. The Vicker’s micro hardness of the joints was measured to be 420 ± 30 Hv, which is higher than that of substrate hardness 230 ± 10 Hv. The tensile strength of the sample was measured by an universal testing machine and found to be 240 MPa which is about 50% of base material strength. The SEM micrographs of the fractured sample indicate mixed modes of failure during fracture of the joint; both ductile and brittle modes of failures occurred as indicated by dimple and cleavage of the brittle faces, respectively.     

Delineating the role of phytocompounds against anti-bacterial drug resistance–An update

Antibacterial resistance developed by bacteria due to the unlimited use of antibiotics has posed a challenge forhuman civilization. This kind of problem is not limited to India only, but it is a global concern. Nowadays, manytreatments and medicines for bacterial diseases have been developed. However, they possess some drawbacks.Therefore, the alternative medicine has been used to target the drug resistant mechanisms and such medicines haveless side effects which is becoming necessary. Natural products have traditionally or historically been of importancefor the development of antibacterial agents and are also known to overcome bacterial drug resistance by directlytargeting the drug resistance mechanisms in bacteria. In recent years, researchers have also focused on new drugdiscovery from plant-based research. They have looked on various phytocompounds as antibacterial agents. In thecurrent review, we report various classes of secondary metabolites such as phenolic compounds, flavonoids, alkaloids,saponins, terpenes, quinones, and some essential oils that have been used as an antibacterial agent. In addition, wealso discuss several mechanisms behind bacterial multi-drug resistance that are used during bacterial pathogenesis.     

A STUDY OF HIGH PRESSURE WATER JETS FOR CUTTING CHICKEN BREAST MEAT

A replicated experiment was conducted to determine optimum settings for orifice size, operating pressure, and nozzle traverse speed for cutting boneless chicken breast meat with high-pressure water jets. Three orifices of 0.076, 0.127 and 0.178 mm were tested with different water pressures in the 90 to 224 MPa range and nozzle traverse speeds in the 50 to 800 mm/s range. A 0.127-mm orifice working with water pressure in the range of 179 to 224 MPa and at 100 mm/s or slower cutting speed gave best results in this study to produce sharp clean cuts. Water jets from a 0.178-mm orifice frequently caused too much meat loss especially at higher water pressures and slower nozzle speeds. Variations in chicken filet thickness also had significant effect on chicken breast meat cutting quality and depth with both 0.076 and 0.127-mm orifices.     

Surface Tension of ZrF4-BaF2-LaF3 Glass

The surface tension of a 62ZrF₄.33BaF₂.5LaF₃ (mol%) glass was measured by a solidified pendant drop technique. The surface tension at 550°C is 0.174 ± 0.005 J/m².