Solid-phase extraction of pesticides from surface water using discs,bulk sorbents and supercritical fluid extraction (SFE)     

Staffan Bengtsson  Tomas Berglf  Sophia Granat  Gran Jonsll 《Pest management science》1994,41(1):55-60

Extraction of pesticides from river water samples using the classical liquid-liquid extraction (LLE) approach is a labour-intensive procedure that requires relatively large volumes of solvent. With the solid-phase extraction (SPE) technique using membranes, the volumes of solvent are reduced. However, it is necessary to pre-filter and often also to acidify the river water to pH < 2 to prevent plugging of the capillary pores. This low pH may decompose some pesticides and therefore a fast and inexpensive technique with bulk sorbent and without prefiltration and acidification was developed. To reduce the solvent volumes further, extractions of discs and bulk sorbent were performed with supercritical fluids (SF). Seven pesticides with different polarities were studied. Mean recoveries from the bulk sorbent and the discs were of the same order (61%). However, recoveries from the latter improved to 82% with SFE of the discs, providing results comparable to LLE (94%) recovery.  相似文献   

Genotypic characterization by spoligotyping and VNTR typing of Mycobacterium bovis and Mycobacterium caprae isolates from cattle of Tunisia     

Hela Lamine-Khemiri  Remigio Martínez  Waldo Luis García-Jiménez  Jose Manuel Benítez-Medina  Maria Cortés  Inés Hurtado  Mohammed Salah Abassi  Imed Khazri  Mohammed Benzarti  Javier Hermoso-de-Mendoza 《Tropical animal health and production》2014,46(2):305-311

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Weaning of juvenile pikeperch, Stizostedion lucioperca L., and perch, Perca fluviatilis L., to formulated feed     

L Ljunggren  F Staffan  S Falk  B Lindén  & J Mendes 《Aquaculture Research》2003,34(4):281-287

Weaning success of pond‐cultured pikeperch and wild‐caught perch (mean length 51 and 48 mm respectively) was evaluated using different weaning techniques and different formulated feeds. Juveniles that were fed formulated feed grew as well as or better than juveniles that were weaned successively using zooplankton or yolk. Four different formulated feeds (agglomerated marine larvae feed, marine larvae feed, trout feed and a semi‐moist feed) were evaluated regarding specific growth rate (SGR), condition factor and a subjective stomach fullness estimate. The agglomerated marine larvae feed gave significantly better weaning performance than the other feeds regarding all parameters (SGR = 7.3% day^?1 and 3.4% day^?1 for pikeperch and perch respectively).  相似文献   

Utilization of nitrogen and energy by Holstein steers fed formaldehyde- and formic acid-treated alfalfa or orchardgrass silage at two intakes     

G A Varga  H F Tyrrell  G B Huntington  D R Waldo  B P Glenn 《Journal of animal science》1990,68(11):3780-3791

Our objective was to measure the utilization of energy (E) and N by Holstein steers when fed alfalfa and orchardgrass silages offered at 65 and 90 g DM/kg live weight (LW).75 daily. Twelve steers adapted to the Beltsville respiration chambers were assigned to three Latin squares with 42-d periods. Steers in one square had permanent catheters in the portal and two mesenteric veins. Energy and N balance were measured during a 7-d collection of feces and urine that included a 3-d measurement of respiratory exchange. Energy and N variables were not different between catheterized and uncatheterized steers. Apparent digestibilities of DM, OM, CP, neutral detergent solubles and permanganate lignin were higher (P less than .01) and digestibilities of NDF and ADF, hemicellulose and cellulose were lower (P less than .01) for steers consuming alfalfa compared to orchardgrass silage. When fed alfalfa, steers' daily gross energy intake, DE, urine energy, ME, heat production and tissue energy retention were greater (P less than .01) and fecal energy losses were less (P less than .01) than when they were fed orchardgrass. Partial efficiency of ME use for tissue energy (TE) was greater (P less than .01) for steers when fed alfalfa (46.1%) than when fed orchardgrass (35.6%). Apparent ME (kcal/LW.75) required for maintenance of TE was similar for steers when fed alfalfa (133.9) and orchardgrass (131.2) silages. Nitrogen retention (g/d) was 48% greater (P less than .01) for steers when fed alfalfa (30.6) than when fed orchardgrass (20.7). This study demonstrates that steers used ME from alfalfa more efficiently for TE deposition than ME from orchardgrass.  相似文献   

The influence of slope aspect and soil type on immigration and emergence of some northern temperate dung beetles     

Karolina Vessby  Staffan Wiktelius 《Pedobiologia》2003,47(1):39-51

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On "Improving Scientific Communication"     

Waldo WH 《Science (New York, N.Y.)》1955,121(3143):444-445

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Catecholamine-induced alteration in sedimentation behavior of membrane bound beta-adrenergic receptors   总被引：10，自引：0，他引：10  

T K Harden  C U Cotton  G L Waldo  J K Lutton  J P Perkins 《Science (New York, N.Y.)》1980,210(4468):441-443

Incubation of astrocytoma cells with catecholamines results in a decrease in catecholamine-stimulated adenylate cyclase activity and a concomitant alteration in the sedimentation properties of particulate beta-adrenergic receptors. The altered receptors exhibit agonist binding properties similar to those of receptors that are "uncoupled" from adenylate cyclase.  相似文献   

The earthquake of Aug. 10     

Waldo L 《Science (New York, N.Y.)》1884,4(81):144-145

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How to make Meteorological Observations at a Distance above the Earth's Surface     

Waldo F 《Science (New York, N.Y.)》1887,10(232):33-34

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PANAMA: A DISCUSSION OF PRESENT CONDITIONS AND THE PROSPECT     

Waldo FL 《Science (New York, N.Y.)》1906,23(594):769-773

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