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Solubility was measured in the Na−F−SO4 system at 25 °C and at 50 °C. Pure-component solubilities for NaF and Na2SO4 are in agreement with available literature data at 25 °C and at 50 °C. The influence of sodium hydroxide on the solubility of the sodium−fluoride−sulfate double salt (Na3FSO4) was also examined. The solubility of the double salt was decreased as the concentration of sodium hydroxide in solution increased.

Measurements of ammonia emission, especially from cattle buildings, are needed to assess the environmental impact of ammonia. There are no data available for cattle buildings in the United Kingdom because most buildings are naturally ventilated and methods for long-term measurement of emission from naturally ventilated buildings have not been developed.Two measurement methods, based on either the release of a tracer gas or on the pressure difference across ventilation openings, were validated in a full-scale cross-section of a naturally ventilated livestock building against a known release rate of a gaseous pollutant at high and low wind speeds. A good correlation between the measured and the actual release rates was found for the tracer gas method with an average recovery rate of 108%.The method based on pressure difference failed to estimate the ventilation rate correctly when only measured pressure coefficients were used, because the measurements of mass flow rates in and out through all openings of the building failed to balance. The traditional approach, based on measured values for the external pressure coefficients and an estimate of the internal coefficient balanced the flow through the building by definition, but failed to estimate the actual emission rate correctly. Current knowledge of the discharge coefficient for the opening designs of the building is insufficient for the pressure difference method to be used to estimate the ventilation rate.Using the tracer method, measurements were carried out between February and May 1996 in a straw-based beef house and a slurry-based dairy cow house with cubicles and scraped passage ways. The buildings were space boarded and had a covered ridge. The ammonia emission was estimated to be 3·5 and 8·9 kg NH3per livestock unit per year for the beef and dairy buildings, respectively.

Given the important role of ammonia emissions in atmospheric chemistry and subsequent damage to the environment, and given that livestock production is the major source of these emissions, there is a strong need for good methods to measure ammonia emission rates from livestock buildings and slurry or manure stores e.g. to guide abatement strategies. In this paper, techniques needed when monitoring these emission rates have been reviewed. The review thus amplifies and extends a consideration of the basic approaches to the above measuring task, presented in a companion review paper.A wide range of techniques was identified for measuring low concentrations of ammonia in air, for measuring airflow rates and for directly measuring ammonia flux rates. The ‘ammonia measurement by annular denuder sampling with on-line analysis’ (AMANDA) rotary annular denuder is recommended as the best technique overall for measuring ammonia concentrations. Wet chemistry offers a less sophisticated but generally acceptable alternative: acid bubblers or simple active denuders can measure ammonia concentrations reliably, while ‘Ferm tube’ passive samplers offer the potential for measuring ammonia fluxes directly, thus eliminating the need for any measurement of airflows. Acid bubblers and Ferm tubes are both cheaper than the AMANDA, but, unlike the AMANDA, cannot measure continuously.If an approach to determining the emission rate from a building is chosen which necessitates the measurement of ventilation rate, then the use of fan-wheel anemometers should be considered where the building is force-ventilated. If, however, the building is naturally ventilated, a tracer gas method is necessary. Sulphur hexafluoride is the recommended tracer, not only for this latter scenario, but also for use with the tracer ratio method for determining source strengths directly.

A full-scale, laboratory building section at Silsoe Research Institute was adapted to simulate cross-ventilating airflow patterns representative of those that develop in naturally ventilated, intensive livestock buildings. In the fully controlled, steady-state environment of the building section, the distribution of aerial pollutants and/or tracers was shown to depend on source location and ventilation rate. No single location within the building showed a consistently representative concentration of tracer that would be suitable for calculating ventilation rate by the constant release tracer method. Estimates of ventilation rate using the constant release tracer method, based on the average concentration of groups of six sampling locations within the building section, ranged from 93 to 119% of the ventilation rate measured using calibrated fan-wheel anemometers placed in the ventilation ducts. The best estimates of ventilation rate were obtained when the tracer concentration was measured at the perimeter (in the outlets and inlets) of the building section—these ranged from 99 to 109% of the ventilation rate measured using the fan-wheel anemometers.Airflow and pollutant distribution in the building section were predicted using computational fluid dynamics (CFD). However, these predictions were of limited help as a tool to select sampling locations within the building section, because the use of CFD requires the selection of parameters which entails verification of predictions against experimental data. Visualization of the airflow by smoke was simpler and more suitable for the present purpose.

A model to optimize the design of biofilters for livestock buildings is presented. This was developed from four sub-models covering biofilter size, biological performance, pressure drop and costs. The sub-model for biological performance predicts that for a specified duty, residence time multiplied by effective surface area of packing is constant. Hence direct comparison of different packing media can be made without the need to quantify the difficult parameter of odour. Five different packing media were compared, based on given inputs. The model predicts that peat and heather, a common packing medium, is the cheapest packing when fewer than 5000 broilers are housed.

The pressure drop per unit depth (ΔP Pa/m) across seven potential minimum-cost biofilter media was determined at different moisture contents for superficial air velocities (u) between 0·03 and 0·13 m/s in pilot scale biofilters, and fitted to the equation ΔP = au^b where a and b are constants. Mean values of a ranged from around 200, for pure heather, to around 6000 for a peat-heather mixture. Mean values of b ranged from 1·20, for coir, to 1·69 for softwood chips of over 75 mm screen size. Estimates were made of particle specific surface area and void fraction, under the conditions of use, for some of the packing media, thus allowing calculation of the modified Reynolds numbers prevailing during the experiments. This showed that the values of b observed experimentally were within the range expected from the Kozeny-Carman theory. Based on the physical characteristics of the various packing media studied, soft-wood chips of over 75 mm screen size appeared to be the most promising because they gave one of the lowest pressure drops, the lowest coefficient of variation for air distribution across the packing, and were the least compressible. All of these three physical factors are important for efficient, minimum-cost operation of biofilters in agricultural buildings. Copyright 1995, 1999 Academic Press

Mixing of ingredients, or dispersion of one phase into another, is an important process in many agricultural and food production systems. In most batch mixing processes, the object is to make a spatially homogeneous product, using the minimum amount of energy, or sometimes in the minimum amount of time. For continuous processes, the object is to obtain a given (uniform) concentration of one, or more, of the mixture components in the outflow product, which does not vary with time. This is the fourth part of a series of papers reviewing mixing processes: in this paper, various methods of describing the completeness of mixing for batch and, to a lesser extent, continuous processes are discussed. Assessment of the degree of mixedness of a system involves proper sampling procedures and methods of quantifying the mixing state. A variety of mixing indices and their use as measures of mixture quality are reviewed for both fluid and particulate mixtures, and one, designated M₇ in this paper, is recommended as it ranges conveniently from 0 to 1, provides good discrimination over the full range of mixing time and is relatively insensitive to the number of particles in a sample of particulate mixture. Techniques for monitoring the state of a mixing process at both laboratory and full industrial scales are also described. Copyright 1994, 1999 Academic Press

This report describes studies designed to evaluate possible inhibitory effects of diaminoantifolates on folate-dependent biosynthetic enzymes in intact L1210 leukemia cells. A novel approach is described which involves an assessment of the metabolism of and biosynthetic flux of the one-carbon moiety from (6S)5-formyltetrahydrofolate in folate-depleted cells. Pretreatment with methotrexate (10 microM), resulting in the formation of methotrexate polyglutamates, or continuous incubation with trimetrexate (1 microM) inhibited growth of folate-depleted L1210 cells in the presence of folic acid or 5-formyltetrahydrolate. In both control and drug-treated cells, double-labeled (6S)-5-[14C]formyl[3H]tetrahydrofolate was rapidly metabolized with the loss of the [14C]formyl group. Under all conditions, the predominant metabolite was 10-formyl[3H]tetrahydrofolate, detectable both intracellularly and extracellularly. In drug-treated cells, there was a remarkably small decrease in the level of 10-formyl[3H]tetrahydrofolate (approximately 30%) and a 10-fold rise in the level of [3H]dihydrofolate to less than 20% of the total folate pool. The incorporation of [14C]formyl group from 5-[14C]formyltetrahydrofolate into thymidylate, serine, and methionine was unaffected by the presence of 1 microM trimetrexate, consistent with the generation of sufficient 5,10-[14C]methylenetetrahydrofolate to drive these reactions. Similarly, the presence of methotrexate polyglutamates had no effect at the level of amino acid synthesis; however, carbon transfer into thymidylate was markedly inhibited. Even though 10-formyltetrahydrofolate was readily formed from 5-formyltetrahydrofolate in this model, the net incorporation of 14C from 5-[14C]formyltetrahydrofolate into purine nucleotides was inhibited by both methotrexate and trimetrexate treatments. Similar findings were obtained when [14C]glycine incorporation into purine nucleotides was monitored in cells incubated with unlabeled 5-formyltetrahydrofolate. Finally, in antifolate-treated cells incubated with unlabeled 5-formyl-tetrahydrofolate, transfer of 14C from [14C]formate or [14C]serine into biosynthetic products or incorporation of [3H]deoxyuridine into nucleic acids was potently inhibited. These results suggest that insufficient levels of tetrahydrofolate and 5, 10-methylenetetrahydrofolate were formed to drive these reactions despite the presence of high levels of 10-formyltetrahydrofolate.(ABSTRACT TRUNCATED AT 400 WORDS)

Summary A radioimmunoassay for melatonin has been developed and used to measure the level of melatonin of male and post-menopausal female patients coming to operation for benign and malignant conditions. The amount of melatonin in the serum of the females was considerably lower than that in males. No difference could be found between patients suffering from benign and malignant conditions.

Agricultural animal production is increasingly regarded as a source of gases which are both aggravating and ecologically harmful. An overview of the origin, number and quantity of trace gases emitted from animal housing and from manure stores is presented and possible means of preventing or reducing them are discussed. Of the 136 trace gases in the air of animal houses, ammonia and methane present the greatest risk to the environment. Quantitative information on concentrations found in air is available for only 23 of these gases. The gases are emitted principally from freshly deposited and stored excreta, from animal feed and from the animals themselves. Future work should determine sources and quantities of the gases emitted from animal housing more precisely and should aim to investigate the potential of these gases to cause damage to man, animals and environment. Total ammonia emissions from animal production in the former West Germany are estimated as approximately 300 000 to 700 000 t/a. It is calculated that between 10 and 23 kg/ha of nitrogen a year enters the soil via the air from these sources, the average of which is higher than the average "critical loads" for most natural habitats. However, there is still a shortage of satisfactory information on the extent of emissions, in particular on those from naturally ventilated animal houses. Ammonia has a direct effect on the trees in the area surrounding animal houses and is also transported long distances through the air causing eutrophication and acidification of water and soil. This frequently results in changes in plant ecology, hence reducing plant diversity. Reduction measures must begin with the housing and manure removal systems and with feeding and management. Factors such as the protein content of feeds, the pH value of slurry and feed additives, air temperature, air exchange rate and litter affect the extent of ammonia emissions from animal housing. Sustained reduction of emissions from outdoor stores is possible by using various coverings. The greatest research need is perceived to be in the area of feed practices which reduce nitrogen and the development of low emission housing and manure removal systems as well as in a detailed compilation of emission factors. As regards the environment, probably the most important carbon-containing gas is methane, which contributes to the "greenhouse effect". Emissions from animal husbandry in Germany are estimated at about 2Mt/a. This corresponds to 0·15% of the assumed global emission from all sources. There is still little knowledge about the quantities of the greenhouse gas nitrous oxide (N₂0) released from agricultural animals. It is estimated that agriculture in Germany emits between 5 and 23 kt/a. It will take some time for reduction measures to be put into practice and the possibility of reducing livestock numbers should also be included in the discussion. Ammonia emissions from animal production represent a considerable loss in valuable fertilizer nitrogen. A reduction in emissions is therefore necessary not only for environmental protection but also to minimize economic loss. Copyright 1994, 1999 Academic Press

Alleles of the HLA DQA1, LDLR, GYPA, HGBB, D7S8 and GC loci, which are amplified using the AmpliType® PM PCR Reaction Mix and Primer Set, can be detected using sequence-specific oligonucleotide probes immobilized on a nylon membrane strip. Using reagents supplied in AmpliType PCR Amplification and Typing Kits, patterns of blue dots corresponding to particular alleles are visualized on the DNA probe strips. Frequently, the correct interpretation of typing results is dependent not only on the presence of probe signals but also on their relative intensities. The relative probe signal intensities obtained from an undegraded DNA sample extracted from a single individual will be different from those obtained from degraded DNA and from samples containing DNA from more than one source. Because probe signal intensity is an essential consideration for interpretation, factors that can influence it need to be identified. Clearly, the time and temperature of the assay steps and the salt concentration in the typing solutions can affect probe signal intensity. Also, if heat-denatured PCR products are allowed to cool for several minutes, the strands will reanneal and become unavailable for binding to the probes immobilized on the strips. However, the selective loss of GC B and HLA DQA1 4.1 probe signals observed after shorter cooling times cannot be explained by these factors. We demonstrate that following heat denaturation of PM PCR products there is sufficient residual TaqDNA polymerase activity to extend primers as the solution cools and that this primer extension occurs at a more rapid rate than PCR product reannealing. Primer extension across probe binding sites will prevent hybridization of the PCR product to complementary probes on the strip. The extent of signal reduction is dependent on the position of the probe binding site relative to the 3′ ends of the primers and on the strand to which the probe is complementary. We recommend a simple modification to the AmpliType typing protocol to ensure all probe binding sites will be available for hybridization to PM and HLA DQA1 DNA probe strips.