Search Results - (Author, Cooperation:C. A. Watson)

2013-11-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2013-10-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2012-01-20

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

1475-2743

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract. Formulation of nitrogen balances on farms requires accurate information on all inputs of the nutrient. N2-fixation by legumes, particularly forage legumes, is an important input which is difficult to measure. Simple regression models have been established from the literature for predicting N2-fixation by grass–white clover (Trifolium repens) mixtures using dry matter yields.Linear relationships were obtained between the N2- fixation (Nfix) and the extra dry matter production of mixed swards (Md) compared with pure grass swards. Nitrogen fixation was given by Nfix= A + 0.067Md where A is the intercept having a value of 6.8 for cut swards and -168.1 for grazed swards. A common slope was adopted because the F statistics showed that slopes fitted separately were not significantly different. The value of the negative intercept represents the supply of N to the grazed sward from soil and excreta-derived N. The regression equation for the cut sward gave reasonable predictions (r2= 0.953) of values of N2-fixed for experimental data not used in establishing the relationship. For grazed grass, the approach over-estimated the N2- fixation by an average of 15%.

Electronic Resource

1365-2389

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

The production of fine roots is one of the principal means by which carbon, fixed during photosynthesis, enters the soil, and quantifying the production for particular combinations of environmental and biotic factors is important for predicting the sequestration of carbon in the soils of grassland ecosystems. Arbuscular mycorrhizal fungi (AMF) can have a major effect on the production of roots, and we studied how colonization by AMF affects the lifespan of roots. Twenty per cent of control roots of Trifolium repens survived for longer than 42 days whereas 37% survived that long in AMF-colonized plants. The overall survival of the roots of Lolium perenne was less than in T. repens: around 10% of roots survived beyond 42 days and this was not affected by AMF colonization. Previous studies have shown that lifespans of roots can be affected by temperature. We tested the hypothesis that these observations are linked to a change in the morphology of the root system caused by temperature and also by AMF. We found that inoculation with AMF in a microcosm study using Plantago lanceolata grown at various temperatures, with and without AMF, showed no clear effect of AMF on branching patterns. Temperature had a significant effect on total lengths, numbers and branching rates of some higher orders of roots. Total lengths of both secondary and tertiary roots grown at 27°C were about double those of plants grown at 15°C. Colonization by AMF tended to reduce this effect. Evidently the effect of colonization by AMF on root lifespan depends on the species. Increased branching, and thus a greater proportion of ephemeral roots, was responsible for shortening the lives of the roots at increased temperature, which suggests a strong link between lifespan and morphology.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

This study shows that both campesteryl palmitate and Sitosteryl palmitate are present in wheat flour. These two saturated steryl esters, which appeared as one spot by thin-layer chromatography, were identified as the palmitates of campesterol and sitosterol by gas-liquid chrmoatography and infrared studies. Campesteryl palmitate and sitosteryl palmitate were present in proportions of about 1 to 5 in wheat flour in amounts of 0.0043 and 0.021%, respectively.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Some effects of egg albumen, gelatin, methyl cellulose c(MC) and carboxymethyl cellulose (CMC) on the gelatinization of unmodified corn and waxy maize starches are reported. The effect of increasing concentrations of those four substances on gelatinization of the starch was determined at 70, 80, and 100°C, and with 40, 60, and 80% moisture. The main criterion for the amount of gelatinization was the susceptibility of the starch to beta-amylase.Albumen, at the higher concentrations employed, inhibited gelatinization of the starches heated at 70°C with 60 and 80% moisture but did not affect degree of gelatinization at higher moisture levels or at higher temperatures. Gelatin inhibited gelatinization of the starches heated at 70°C more than did albumen, and inhibited to some degree the gelatinization of starches heated to 80°C with 60% moisture. At higher moisture levels and temperatures, gelatin had no effect on extent of starch gelatinization. Methyl cellulose significantly affected starch gelatinization at 70°C but had less and no effect at 80 and 100°C, respectively. Carboxymethyl cellulose had pronounced effect on starch gelatinization at all temperatures and moisture levels except the 80% moisture level system heated at 100°C.In bread dough containing between 36 to 38% moisture, starch gelatinization increased with temperature in the center of the loaf. The rate of increase of starch gelatinization was less than the rate of increase of temperature during baking.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

SUMMARY Bulk volume expands or contracts when solid particles of fairly uniform size flow out of a container by gravity and are loaded into another container. Expansion or contraction depends on the initial void fraction of the bulk volume. In this study, only expansion of the bulk volume was studied. The expansion was measured after wheat and spherical Lucite particles flowed separately through a plain tube and through a motionless mixer. It was found that expansion of the bulk volume was independent both of the number of helices in the mixer and the length of the plain tube. Passing wheat particles through the mixer expanded their bulk 3–4% less than did passing them through a plain tube of the same distance. Using 3/16-in. particles, the mixer gave 3% less bulk volume expansion. For a given weight range of particles (using the expanded volume in the plain tube as a basis) the mixer reduced the expanded volume of wheat 20% and reduced more than 40% of the expanded volume of 3/16-in. Lucite particles. The degree of mixedness, a measure of radial mixing, increased exponentially as the number of helices in a motionless mixer increased. Use of four helices for mixing 3/16-in. Lucite particles, six helices for mixing 1/8-in. particles and six helices for mixing red and white wheat appears to be optimum for the operating conditions in this study.

Electronic Resource

1573-0867

available N ; cover crop ; crop uptake ; green manure ; incorporation ; N2O

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Nitrogen retention and release following the incorporation of cover crops and green manures were examined in field trials in NE Scotland. These treatments reduced the amounts of nitrate-N by between 10–20 kg ha-1 thereby lowering the potential for leaching and gaseous N losses. However, uptake of N by overwintering crops was low, reflecting the short day-lengths and low soil temperatures associated with this part of Britain. Vegetation that had regenerated naturally was as effective as sown cover crops at taking up N over winter and in returning N to the soil for the following crop. Incorporation of residues generally resulted in lower mineralisation rates and reduced N2O emissions than the cultivation of bare ground, indicating a temporary immobilisation of soil N following incorporation. Emissions from incorporated cover crops ranged from 23–44 g N2O-N ha-1 over 19 days, compared with 61 g N2O-N ha-1 emitted from bare ground. Emissions from incorporated green manures ranged from 409–580 g N2O-N ha-1 over 53 days with 462 g N2O-N ha-1 emitted from bare ground. Significant positive correlations between N2O and soil NO3 - after incorporation (r=0.8–0.9; P〈0.001 and r=0.1–0.4; P〈0.05 for cover crops and green manures, respectively) suggest that this N2O was mainly produced during nitrification. There was no significant effect of either cover cropping or green manuring on the N content or yield of the subsequent oats crop, suggesting that N was not sufficiently limiting in this soil for any benefits to become apparent immediately. However, benefits of increased sustainability as a result of increased organic matter concentrations may be seen in long-term organic rotations, and such systems warrant investigation.

Electronic Resource

0001-1541

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Process Engineering, Biotechnology, Nutrition Technology

A Markov chain model was used to model the axial mixing of solid particles in a motionless mixer having no moving parts. One step transition probabilities were determined experimentally for the model. Based on these transition probabilities, the model was able to predict spatial distribution of tracer particles up to seven steps of the Markov chain, which was equivalent to seven consecutive passes of the mixture through the mixer. Experimental results were in good agreement with those predicted from the Markov chain model.

9 Ill.

Electronic Resource