Analysis of ultracentrifugation interference patterns with image digitizer: Application to molecular weight determination of SRM 1478 polystyrene

A new method for the analysis of ultracentrifugation interference patterns with the use of a commercial image digitizer is given. The application of the method to the sedimentation equilibrium data for SRM 1478 polystyrene leads to a weight-average molecular weight of 37 400 g mol⁻¹ having a sample standard deviation of 0.7% and an expected systematic error limit of 2%.     

Hydrogenation of brown coal. 2. Iron-based catalysis

Some of the inherent cations of Victorian brown coals have been exchanged for iron by treatment with solutions of iron salts. Coals with various iron contents are obtained by variation of the pH of the solutions used. Hydrogenation of coals treated in this way at 395 °C, and an initial hydrogen pressure of 10 MPa, give product yields similar to those obtained using commercial cobalt molybdate on alumina catalysts, and greater than those obtained using red mud as a catalyst. The increase in yields compared with non-catalysed experiments results mainly from increased production of asphaltenes. The amount and composition of gas (80–90 wt% C0₂, resulting from decarboxylation) remains constant. Despite the similar conversions, the hydrogen consumption and tetralin/naphthalene ratios for iron-catalysed experiments are less than for cobalt—molybdate-catalysed experiments.     

Effect of water deficit on yield and protein content in pearl millet grains

Seventy-two pearl millet genotypes were water stressed at panicle development and grain filling stages. Neither grain yields, yield components, protein percent nor total protein per unit area were affected by water deficit during panicle development but protein content per grain was increased. When plants were water stressed during grain filling, grain yield, grains per unit area and 1000 grain weight were reduced, but grain protein percentage increased. Total protein per unit area was reduced primarily due to lower grain yield. The protein content per grain was unaffected by stress, suggesting that the apparent increase in protein percentage is due to reduced carbohydrate accumulation under stress.     

Recombineering reagents for improved inducible expression and selection marker re-use in Schizosaccharomyces pombe

The fission yeast Schizosaccharomyces pombe is an excellent model organism for cell biology. However, its genetic toolbox is less developed than that of Saccharomyces cerevisiae. In the first part of this study we describe an improved inducible expression vector based on tetracycline regulation of the CaMV35S promoter, which is also capable of chromosomal integration and therefore works in minimal and in rich media. We found that anhydrotetracycline is a superior ligand for induction. Maximum expression levels were observed after 12 h in minimal media (EMM) and after 9 h in rich media (YES), which is faster than the nmt1 promoter system. The system was combined with a convenient recombineering-based subcloning strategy for ease of cloning. In the second part we present four template plasmids, pSVEM-bsd, pSVEM-nat, pSVEM-kan and pSVEM-hph, which harbour four recyclable disruption cassettes based on the Cre recombinase lox71/66 strategy for use in PCR targeting methods. Cre-mediated excision leaves a non-functional mutant lox site in the genome, allowing the reiterative usage of these cassettes for multiple targetings. These cassettes are also configured with dual eukaryotic/prokaryotic promoters so that they can be used for recombineering in E. coli. Amongst other purposes, this permits the rapid and convenient creation of targeting constructs with much longer homology arms for difficult and complex targetings in the Sz. pombe genome.     

Alginate coating as carrier of oligofructose and inulin and to maintain the quality of fresh-cut apples

The aim of this study was to apply an edible coating containing prebiotics such as oligofructose and inulin to fresh-cut apple wedges. An assessment of the quality, sensory, polyphenol, and volatile attributes of coated and uncoated fresh-cut apple wedges was also undertaken. Fructan analysis showed that all prebiotics remained stable over the 14-d storage period and an intake of 100 g of apple supplies 1 to 3 g of prebiotics. Browning index, firmness, acidity remained stable throughout the 14 d compared to the control while applying prebiotic coatings resulted in an increase in soluble solids. Sensory and visual assessment indicated acceptable quality of apple wedges coated with prebiotics. HPLC analysis showed that levels of polyphenolic compounds were more stable in coated apple wedges (without prebiotic inclusions) than in uncoated control apples. No difference was found between O(2) and CO(2) headspace concentration of coated and uncoated samples. Significant differences (P < 0.001) were found for headspace volatile production between the samples. Most coated samples showed lower volatile production in the headspace than uncoated samples.     

Quality and antioxidant capacity of fresh‐cut apple wedges enriched with honey by vacuum impregnation

The effect of vacuum impregnation (VI) of fresh‐cut apple wedges with honey, in presence and absence of a browning inhibitor on physicochemical, sensory and antioxidant properties over 7 days of storage at 2–4 °C was studied. Infusion of wedges with honey resulted in very little weight change indicating loss of internal water and ingress of honey carbohydrates into the wedges, hence the correlation coefficients with soluble solids content (r = ?0.91) and dry matter (r = ?0.77). Water infused samples showed the highest water uptake resulting in an increase in weight of 30%. Browning (P < 0.001) and firmness (P < 0.001) of apple wedges were the quality parameters most affected by VI. Samples dipped in browning inhibitor prior AS1 showed slightly better performance than undipped wedges with regard to browning and firmness. Total phenol content and antioxidant activity were significantly (P < 0.001) lower for honey infused apple wedges.     

Determination of stability constants of U(VI)-Fe(III)-citrate complexes

Ion-exchange experiments were performed to evaluate the formation of the uranium-citrate and uranium-iron-citrate complexes over a wide concentration range; i.e., environmentally relevant concentrations (e.g., 10(-6) M in metal and ligand) and concentrations useful for spectroscopic investigations (e.g., 10(-4) M in metal and ligand). The stability of the well-known uranium-citrate complex was determined to validate the computational and experimental methods applied to the more complex system. Values of the conditional stability constants for these species were obtained using a chemical equilibrium model in FITEQL. At a pH of 4.0, the stability constant for uranium-citrate complex (log beta1,1) was determined to be 8.71+/-0.6 at I = 0. Analysis of the results of ion-exchange experiments for the U-Fe-citric acid system indicates the formation of the 1:1:1 and 1:1:2 ternary species with stability constants (log beta) of 17.10+/-0.41 and 20.47+/-0.31, respectively, at I= 0.     

Comparing GC–MS,HPLC and H NMR analysis of beef longissimus dorsi tissue extracts to determine the effect of suspension technique and ageing

Beef longissimus dorsi muscle samples matured over a 21 day period were analysed using three different analytical techniques; ¹H NMR, GC–MS and HPLC. The data from the three experimental techniques were correlated with each other to determine if the results were statistically similar to each other. From our analysis we determined that the metabolites measured using ¹H NMR were statistically similar to the compounds quantified using the chromatography techniques (p < 0.001). In addition, using PCA, we were able to show that different metabolites, measured using the various analytical techniques produced very similar scores and loadings plots for all the analysis and extraction techniques undertaken across the 21 day time domain. Using a combination of these three different techniques provides a unique and holistic insight into the biochemistry behind the conversion of muscle to meat which would not be possible using any single technique alone.     

Effect of high hydrostatic pressure and thermal processing on the nutritional quality and enzyme activity of fruit smoothies

Fruit smoothie samples were thermally (P₇₀ > 10 min) or high hydrostatic pressure (HHP) processed (450 MPa/20 °C/5 min or 600 MPa/20 °C/10 min) and the total antioxidant capacity (TAC), levels of antioxidant groups [total phenols (TP), anthocyanins and ascorbic acid], instrumental colour, polyphenol oxidase (PPO) enzyme activity and dissolved oxygen were examined over a storage period of 10 h at 4 °C. Thermal processing of smoothies reduced (p < 0.001) TAC and TP values, ascorbic acid and L and a colour attributes (lightness and redness respectively) compared to fresh and HHP-450 processed samples. Conversely, it did result in complete inactivation of PPO enzyme, with no activity detected. Of the HHP treatments, HHP-450 samples had higher (p < 0.001) levels of total antioxidant, phenols and anthocyanin content than HHP-600 samples. However, the latter was more effective in reducing (p < 0.001) the endogenous enzyme activity of the smoothies. .Ascorbic acid content degraded over the storage for all smoothies. HHP-600 samples had high initial values, which declined slowly over storage, while thermal samples had the lowest initial value (0.5 h) that fell below detectable limits by 10 h. Despite these data, less pronounced effects were observed for storage. No significant effects were observed for total anthocyanin and phenolic contents as well as L and colour change (ΔE) variables. Overall, HHP processing of smoothies at moderate temperatures may be a suitable alternative to traditional thermal processing.