Self-service computerized bibliographic retrieval: a comparison of Colleague and PaperChase, programs that search the MEDLINE data base

Colleague and PaperChase are the two most widely used computer systems designed specifically for clinicians and scientists who wish to search the National Library of Medicine's MEDLINE data base of references to the biomedical literature. The present study compares the performance of these two systems. Two matched groups of second-year medical students each received 3 hr of instruction, one group in Colleague, the other in PaperChase. Each student then attempted 10 test searches. The next day the groups were reversed, and each student attempted 5 additional searches. During 3 1/2 hr allocated for searching, users of Colleague attempted 64 test searches and retrieved 326 target references; users of PaperChase attempted 78 searches and retrieved 496. Users of Colleague took a mean of 2.2 min and spent a mean of $1.20 to find each target reference; users of PaperChase took 1.6 min and spent $0.92. We conclude that after limited training, medical students find more references faster and at lower cost with PaperChase than with Colleague.     

Production Flow Line System Design-A Review

Problems associated with the design and operation of manual production flow line systems are identified and discussed. Research findings and currently available techniques are examined in the light of these problems and the nature of research, both past and present, is critically examined in an attempt to develop strategies for future work.     

High rates of [1-14C]acetate incorporation into the lipid of isolated spinach chloroplasts

Spinach chloroplasts, isolated by techniques yielding preparations with high O2- evolving activity, showed rates of light-dependent acetate incorporation into lipids 3-4 fold higher than any previously reported. Incorporation rates as high as 500 nmol of acetate/h per mg of chlorophyll were measured in buffered sorbitol solutions containing only NaHCO3 and [1-14C]acetate, and as high as 800 nmol/h per mg of chlorophyll when 0.13 mM-Triton X-100 was also included in the reaction media. The fatty acids synthesized were predominantly oleic (70-80% of the total fatty acid radioactivity) and palmitic (20-25%) with only minor amounts (1-5%) of linoleic acid. Linolenic acid synthesis was not detected in the system in vitro. Free fatty acids accounted for 70-90% of the radioactivity incorporated and the remainder was shared fairly evenly between 1,2-diacylglycerols and polar lipids. Oleic acid constituted 80-90% of the free fatty acids synthesized, but the diacylglycerols and polar lipids contained slightly more palmitic acid than oleic acid. Triton X-100 stimulated the synthesis of diacylglycerols 3-6 fold, but stimulated free fatty acid synthesis only 1-1.5-fold. Added glycerol 1-phosphate stimulated both the synthesis of diacylglycerols and palmitic acid relative to oleic acid, but did not increase acetate incorporation into total chloroplast lipids. CoA and ATP, when added separately, stimulated acetate incorporation into chloroplast lipids to variable extents and had no effect on the types of lipid synthesized, but when added together resulted in 34% of the incorporated acetate appearing in long-chain acyl-CoA. Pyruvate was a much less effective precursor of chloroplast fatty acids than was acetate.     

Household hazardous waste in municipal landfills: contaminants in leachate

Household hazardous waste (HHW) includes waste from a number of household products such as paint, garden pesticides, pharmaceuticals, photographic chemicals, certain detergents, personal care products, fluorescent tubes, waste oil, heavy metal-containing batteries, wood treated with dangerous substances, waste electronic and electrical equipment and discarded CFC-containing equipment. Data on the amounts of HHW discarded are very limited and are hampered by insufficient definitions of what constitutes HHW. Consequently, the risks associated with the disposal of HHW to landfill have not been fully elucidated. This work has focused on the assessment of data concerning the presence of hazardous chemicals in leachates as evidence of the disposal of HHW in municipal landfills. Evidence is sought from a number of sources on the occurrence in landfill leachates of hazardous components (heavy metals and xenobiotic organic compounds [XOC]) from household products and the possible disposal-to-emissions pathways occurring within landfills. This review demonstrates that a broad range of xenobiotic compounds occurring in leachate can be linked to HHW but further work is required to assess whether such compounds pose a risk to the environment and human health as a result of leakage/seepage or through treatment and discharge.     

Calcium carbonate hexahydrate: Its properties and formation in lime-soda softening

The properties and the conditions of formation of a metastable hydrated form of calcium carbonate (CaCO₃6H₂O) are described. This compound often crystallises when Essex river waters are softened by the lime/soda process. Formation of the hydrated salt is favoured by low water temperatures and by high orthophosphate levels. Calcium carbonate hexahydrate forms pure well-defined crystals which are considerably more soluble in water than calcite, the usual product of lime/soda softening. The efficiency of the softening process is very much reduced when the hydrated compound crystallises, and increased quantities of chemicals are required both for softening and for subsequent stabilisation of the softened water.Considerable success has been achieved on the practical scale in reducing the incidence of formation of the hexahydrate by precipitating phosphate before softening using ferric salts and by addition of pre-formed calcite nuclei in the form of commercial Whiting; this has led to substantial economies in chemical consumption.     

Generation of phospholipid artefacts during extraction of developing soybean seeds with methanolic solvents

The major phospholipids of soybean cotyledons during development were phosphatidylcholine (45–55%), phosphatidylethanolamine (24–28%), and phosphatidylinositol (15–18%) when the tissue was steam-killed prior to extraction of the lipids. The only other phospholipids of any significance (4–6%) was identified as phosphatidylglycerol. Phosphatidic acid was a minor constituent (<1%), and neither N-acyl phosphatidylethanolamine norbis-phosphatidic acid were detected in appreciable (>0.1% of the total lipid phosphorus) quantities. When fresh cotyledons were rapidly homogenized in mixtures of chloroform and methanol or in methanol alone, phosphatidylmethanol was formed in variable amounts (0–20% of the total phospholipid), and when cotyledons were soaked in methanol prior to homogenizing, phosphatidylmethanol became the major phospholipid, accounting for up to 75% of the total lipid phosphorus. Phosphatidylmethanol was formed by the phospholipase D-catalyzed transphosphatidylation of phosphatidylcholine and phosphatidylethanolamine during extraction.     

THE FRACTIONATION OF POLYPEPTIDES FROM BARLEY AND BEER BY HYDROPHOBIC INTERACTION CHROMATOGRAPHY: THE INFLUENCE OF THEIR HYDROPHOBICITY ON FOAM STABILITY

Polypeptides from beer and from aqueous extracts of barley have been separated by hydrophobic interaction chromatography. The most stable foams are given by polypeptides of greatest hydrophobic character whereas hydrophilic polypeptides give much less stable foams. This effect is most pronounced in polypeptides of molecular size between 5000 and 30,000 and less so in the case of high molecular weight polypeptides (> 50,000).     

Performance of a CO2 sorbent for indoor air cleaning applications: Effects of environmental conditions,sorbent aging,and adsorption of co-occurring formaldehyde

Indoor air cleaning systems that incorporate CO₂ sorbent materials enable HVAC load shifting and efficiency improvements. This study developed a bench-scale experimental system to evaluate the performance of a sorbent under controlled operation conditions. A thermostatic holder containing 3.15 g sorbent was connected to a manifold that delivered CO₂-enriched air at a known temperature and relative humidity (RH). The air stream was also enriched with 0.8-2.1 ppm formaldehyde. The CO₂ concentration was monitored in real-time upstream and downstream of the sorbent, and integrated formaldehyde samples were collected at different times using DNPH-coated silica cartridges. Sorbent regeneration was carried out by circulating clean air in countercurrent. Almost 200 loading/regeneration cycles were performed in the span of 17 months, from which 104 were carried out at reference test conditions defined by loading with air at 25°C, 38% RH, and 1000 ppm CO₂, and regenerating with air at 80°C, 3% RH and 400 ppm CO₂. The working capacity decreased slightly from 43-44 mg CO₂ per g sorbent to 39-40 mg per g over the 17 months. The capacity increased with lower loading temperature (in the range 15-35°C) and higher regeneration temperature, between 40 and 80°C. The CO₂ capacity was not sensitive to the moisture content in the range 6-9 g/m³, and decreased slightly when dry air was used. Loading isothermal breakthrough curves were fitted to three simple adsorption models, verifying that pseudo-first-order kinetics appropriately describes the adsorption process. The model predicted that equilibrium capacities decreased with increasing temperature from 15 to 35°C, while adsorption rate constants slightly increased. The formaldehyde adsorption efficiency was 80%-99% in different cycles, corresponding to an average capacity of 86 ± 36 µg/g. Formaldehyde was not quantitatively released during regeneration, but its accumulation on the sorbent did not affect CO₂ adsorption.     

Household hazardous waste data for the UK by direct sampling

The amount of household hazardous waste (HHW) disposed of in the United Kingdom (UK) requires assessment. This paper describes a direct analysis study carried out in three areas in southeast England involving over 500 households. Each participating householder was provided with a special bin in which to place items corresponding to a list of HHW. The amount of waste collected was split into nine broad categories: batteries, home maintenance (DIY), vehicle upkeep, pesticides, pet care, pharmaceuticals, photographic chemicals, household cleaners, and printer cartridges. Over 1 T of waste was collected from the sample households over a 32-week period, which would correspond to an estimated 51,000 T if extrapolated to the UK population for the same period or over 7,000 T per month. Details of likely disposal routes adopted by householders were also sought, demonstrating the different pathways selected for different waste categories. Co-disposal with residual household waste dominated for waste batteries and veterinary medicines, hence avoiding classification as hazardous waste under new UK waste regulations. The information can be used to set a baseline for the management of HHW and provides information for an environmental risk assessment of the disposal of such wastes to landfill.