Chromatographic analysis of cadaverine to detect incipient spoilage in mutton

Suitability of measuring cadaverine for rapid assessment of bacterial quality of fresh and stale mutton (showing signs of incipient spoilage) was examined. HPTLC for rapid screening and detection and HPLC for accurate quantification was employed. Analysis of over 150 samples of varying degrees of freshness and postmortem age showed that in more than 90% of the samples, no cadaverine was detectable when meat was deemed acceptable with <10⁶ orgs/g. However, when meat showed incipient spoilage, as judged by off odour and dull colour, cadaverine was detected in the range of 1–5 ppm. Such meat samples had a bacterial load of 10⁷ orgs / g or more. HPTLC analysis allowed the simultaneous analysis of 5–6 samples and the total time including extraction was 1.5–2 h. As only easily available chemicals and equipment were required, it was a simple, rapid and inexpensive technique. HPTLC detection of cadaverine can therefore be recommended for the rapid assessment of bacterial quality of mutton and HPLC can be used for accurate quantification.     

Benchmark results for the critical slab and sphere problem in one-speed neutron transport theory

In this paper benchmark numerical results for the one-speed criticality problem with isotropic scattering for the slab and sphere are reported. The Fredholm integral equations of the second kind based on the Case eigenfunction formalism are numerically solved by Neumann iterations with the Double Exponential quadrature.     

Rapid three-step purification of a hepatic neutral cholesteryl ester hydrolase which is not the pancreatic enzyme

A rat liver cytosolic cholesteryl ester hydrolase (CEH) was purified 12,600-fold by ammonium sulfate precipitation, cation exchange chromatography and gel permeation high-performance liquid chromatography, with an overall yield of 20%. Its properties are compared to those of pancreatic CEH, with which it has sometimes been identified. Liver CEH exhibited a single silver stained band following SDS-polyacrylamide gel electrophoresis (M_r=66 kDa), was activated by 0.5–10 mM taurocholate but was strongly inhibited by higher levels of taurocholate, which activate pancreatic CEH. Whereas bile salts are known to induce formation of a hexamer of pancreatic CEH, in the current study, 0.5 mM taurocholate dissociated a multimeric form of liver CEH to monomer. Liver CEH did not coelute with pancreatic CEH from cation exchange and chromatofocusing columns, exhibited no immunoreactivity with anti-rat pancreatic CEH IgG in Western blots, was not inhibited by anti-rat pancreatic CEH IgG and had a different amino acid composition from pancreatic CEH. In contrast to liver CEH, which is known to be activated by protein kinases A and C, pancreatic CEH was unaffected by cofactors for protein kinase A and was inhibited by cofactors for protein kinase C.     

On time-step bounds in unitary quantum evolution using the Lanczos method

To solve the non-relativistic time dependent Schrödinger equation using the Lanczos method, Park and Light have provided an approximate expression for the time step for a given accuracy. We provide an exact expression for the time step in terms of the eigenvalues and eigenvectors of the resulting tridiagonal matrix. For two test problems, the values of the time step provided by Park and Light differ significantly from the exact values provided by the present method. We also indicate upper and lower bounds for the time step in terms of the maximum and minimum eigenvalues. These bounds indicate the possibility of using a new time step given by the geometric mean of the eigenvalues of the tridiagonal matrix.     

Power Law Fluids in a Circular Curved Tube. Part III. Numerical Simulation of Laminar Flow

The equations of motion and continuity of a fully developed, steady-state, isothermal, incompressible laminar flow of power law fluids within a toroidal-type coiled tube geometry have been solved numerically using the successive overrelaxation method. Numerical solutions have been obtained for curvature ratios from 5 to 100, Dean number from 1 to 300, and power law index from 0.5 to 1.5. Dean's constraint has been relaxed and the numerical solutions for primary and secondary flow, and the numerical results of the friction factor for different values of Dean number, curvature ratio, and power law index have been computed. The solutions have been carefully checked for accuracy and the results are compared with previous studies. The numerical results are found to be consistent with the published results for the case of Newtonian fluids. The ratio of friction factor of a curved tube to a straight tube increases with the Dean number and also with the power law index.     

Histological localization of oil palm fruit lipase

Development of free fatty acids (FFA) and subsequent deterioration of palm oil quality can be attributed to lipase, an active hydrolytic enzyme present in the mesocarp of oil palm fruit. A histochemical method was used to localize this enzyme in the mesocarp. FFA released from endogenous glycerides were precipitated as lead salt. The deposits were located on the membranes of oil bodies. Enzymatic activity in the mesocarp was also studied under different conditions of fruit storage: ambient temperature, freezing, etc. The enzyme was active after freezing but less active under ambient conditions of fruit storage. Investigations on fruit development indicated that the enzyme activity started appearing between 16–20 weeks after anthesis (WAA) which synchronized with the beginnning of lipid formation. These histochemical studies were supported wity biochemical data on FFA.     

Accurate estimation of statistical parametric variation in microelectronic test structures

Advanced technologies of microelectronic device fabrication need accurate determination of process parameters and their analysis. Test structures which represent individual process steps are incorporated in the design. Independent measurements can be carried out on these structures and the information is used as a feedback in order to achieve perfection at different stages of fabrication. This note presents an algorithm for analysis of measurement data and identification of defective sites on the wafer leading to an accurate yield analysis.