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  • Author or Editor: K. K. Tan x
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A method is described for the enthalpimetric determination of inhibition constants based on a previously reported procedure for the determination ofK m, using the integrated Michaelis-Menten equation. The inhibition of the cholinesterase-catalyzed hydrolysis of butyryl-choline by morphine, quinine and procaine is chosen as a model. The results compare favourably with Lineweaver-Burk data.

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Summary  

Some stability and convergence theorems of the modified Ishikawa iterative sequences with errors for asymptotically nonexpansive mapping in the intermediate sense and asymptotically pseudo contractive and uniformly Lipschitzian mappings in Banach spaces are obtained.

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Abstract  

The isoquinoline alkaloids were isolated from traditional Chinese drugs of Phellodendri Cortex, Radix Stephaniae Tetrandrae, Corydalis Yanhusuo and Corydalis Bungeana. The power-time curves of growth of E. coli at different concentrations of isoquinoline alkaloid at 37�C were determined by a 2277 Thermal Activity Monitor. The rate constant of bacteriostastic activity was calculated. The relationship between growth rate constant and concentration was established. The optimum bacteriostastic concentration was determined. Experimental results have indicated that all the isoquinoline alkaloids isolated from the four kinds of traditional Chinese drugs have bacteriostastic activity and the order is Phellodendri Cortex>Radix Stephaniae Tetrandrae>Corydalis Yanhusuo>Corydalis Bungeana.

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Abstract

Methylcellulose (MC) is a thermo-reversible physical hydrogel. This study investigates the thermodynamic characteristics of gelation mechanism for MC. The relative and absolute specific heat capacity values of the hydrogel system were modeled using an empirical formulation to facilitate calculation of thermodynamic parameters. Experiments verifying the assumptions for the model formulation were conducted and are discussed. Parameters such as enthalpy, entropy, and changes in their magnitude as a function of temperature were calculated and their trends were studied. The implications of these observations on the various stages of the gel formation process and the associated mechanisms are evaluated. The studies revealed that the gelation of MC is a temperature- driven process rather than only driven by the heat input, and it attains a state of equilibrium under isothermal conditions. During gelation, the entropy of the overall (MC+water) system increases due to an increase in the disorderliness of the MC system.

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Lactobacilli and bifidobacteria are most commonly encountered in the dairy industries, either existing naturally in milk or inoculated as starters in fermented dairy products. Recent research suggests that fermented dairy products are a cocktail of bioactive ingredients. The objective of our study was to evaluate the bioactivity of cell wall fractions of Lactobacillus and Bifidobacterium grown in reconstituted skimmed milk, and the possibility of intra- and extracellular extracts of these bacteria for applications in foods and beyond. Intracellular and extracellular extracts of Lactobacillus and Bifidobacterium showed inhibitory activities against food and dermal pathogens. All strains were able to produce inhibitors, such as organic acids, antimicrobial peptides, diacetyl, and hydrogen peroxide. Most strains showed higher production of extracellular than intracellular inhibitors (P<0.05). Meanwhile, all strains were able to produce hyaluronic acid, lipoteichoic acid, peptidoglycan, neutral sphingomyelinase and acid sphingomyelinase at concentrations applicable for cosmeceutical application. Findings from our study demonstrated that inhibitors and bioactives from lactobacilli and bifidobacteria have the potential to be developed into formulations for food and non-food applications.

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Chromosome segment substitution lines (CSSLs) are powerful tools to combine naturally occurring genetic variants with favorable alleles in the same genetic backgrounds of elite cultivars. An elite CSSL Z322-1-10 was identified from advanced backcrosses between a japonica cultivar Nipponbare and an elite indica restorer Xihui 18 by SSR marker-assisted selection (MAS). The Z322-1-10 line carries five substitution segments distributed on chromosomes 1, 2, 5, 6 and 10 with an average length of 4.80 Mb. Spikilets per panicle, 1000-grain weight, grain length in the Z322-1-10 line are significantly higher than those in Nipponbare. Quantitative trait loci (QTLs) were identified and mapped for nine agronomic traits in an F3 population derived from the cross between Nipponbare and Z322-1-10 using the restricted maximum likelihood (REML) method in the HPMIXED procedure of SAS. We detected 13 QTLs whose effect ranging from 2.45% to 44.17% in terms of phenotypic variance explained. Of the 13 loci detected, three are major QTL (qGL1, qGW5-1 and qRLW5-1) and they explain 34.68%, 44.17% and 33.05% of the phenotypic variance. The qGL1 locus controls grain length with a typical Mendelian dominance inheritance of 3:1 ratio for long grain to short grain. The already cloned QTL qGW5-1 is linked with a minor QTL for grain width qGW5-2 (13.01%) in the same substitution segment. Similarly, the previously reported qRLW5-1 is also linked with a minor QTL qRLW5-2. Not only the study is important for fine mapping and cloning of the gene qGL1, but also has a great potential for molecular breeding.

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