Stock solution

Abstract: Collagen is a widely used material in biomedical applications. Although processes that prepare collagen and collagen-based materials that show suitable properties after extraction exist, a ready-to-use, easily stockable, with tailored collagen concentration has not yet been developed. Using rat tail tendons, acid soluble collagen solutions were prepared by two different methods. To improve cell viability of pure collagen films, solutions with physiological pH were also prepared by mixing with NaOH solution. Specimens in the form of thin sheets were then fabricated by solvent evaporation. Next, IR spectroscopy, tensile testing techniques as well as human fibroblast cell morphology and cytotoxicity were used to validate the significant variations in the processes. The results demonstrated that, during the synthesis of collagen stock solution, lyophilization and mechanical blending had little effect on the final properties and therefore offers a method for obtaining solutions with a more homogeneous and modifiable collagen concentration and longer storage time. Neutralizing the stock solution with aqueous NaOH prior to solvent evaporation provided films that had lower mechanical properties but significantly improved biological performance.

Abstract: Dosage calculation and stock solution preparation in preclinical studies, involving the use of experimental animals are important in screening and development of new drugs The present literature provides the basic principles and guidelines on dosage calculations and preparation of stock solution (with reference to crude plant extracts, sylimarin tablets, alloxan monohydrate as well as chemiron blood tonic) for experimental animal studies Keywords: Dosage calculation, stock solution preparation, crude plant extract, sylimarin and chemiron blood tonic

Abstract: A central composite rotatable design was used to examine the effects of five components of the medium on the growth of Haematococcus pluvialis in batch culture. The medium components considered were: sodium acetate,potassium nitrate, major elements, trace elements and vitamins. Within the range of the concentrations tested, a moderate concentration of the major elements significantly enhanced algal growth, both in terms of specific growth rate and cell dry weight, whereas the vitamins had no significant effect. Based on the response surface contour plots and the results of numerical analyses, the optimal nutrient concentrations for growth in terms of specific growth rate were 0.51 g L-1 sodium acetate, 0.25 g L-1 potassium nitrate, 0.63 mL L-1 of the major element stock solution and 0.2 mL L-1 of the trace element stock solution. The optimal nutrient concentrations for biomass production were 1.64 g L-1 sodium acetate, 0.37 g L-1potassium nitrate, 2.52 mL L-1 of the major element stock solution and 0.03 mL L-1 of the trace element stock solution.

Abstract: Polydiallyldimethylammonium chloride (polyDADMAC) and epichlorohydrin-dimethylamine (Epi-DMA) stock solutions were prepared, stored for varying amounts of time, and used in bench-scale simulations of coagulation/flocculation/sedimentation to determine whether polymer stock age had an influence on NDMA yields. Stock solution ages ranged from under one hour to fifty hours. PolyDADMAC stock age did not significantly affect NDMA production. Epi-DMA stock age significantly increased NDMA production over a time span of 0 to 5 hours, but not from 5 to 50 hours. The relationship between the change in NDMA yields and Epi-DMA stock solution age may be a first-order reaction or a two-phase process. Statistical evaluation of the data available supports both theories.