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Trapping Efficiency (trapping + efficiency)
Selected AbstractsValidation of a vegetated filter strip model (VFSMOD)HYDROLOGICAL PROCESSES, Issue 5 2001Dr Majed Abu-Zreig Abstract Vegetated filter strips (VFS) are designed to reduce sediment load and other pollutants into water bodies. However, adaptation of VFS in the field has been limited owing to lack of data about their efficiency and performance under natural field conditions. A number of models are available that simulate sediment transport and trapping in VFS, but there is a general lack of confidence in VFS models owing to limited validation studies and model limitations that prevent correct application of these models under field conditions. The objective of this study is to test and validate a process-based model (VFSMOD) that simulates sediment trapping in VFS. This model links three submodels: modified Green,Ampt's infiltration, Quadratic overland flow submodel based on kinematic wave approximation and University of Kentucky sediment filtration model. A total of 20 VFS, 2, 5, 10 and 15 m long and with various vegetation covers, were tested under simulated sediment and runoff conditions. The results of these field experiments were used to validate the VFS model. The model requires 25 input parameters distributed over five input files. All input parameters were either measured or calculated using experimental data. The observed sediment trapping efficiencies varied from 65% in the 2-m long VFS to 92% in the 10-m long filters. No increase in sediment removal efficiency was observed at higher VFS length. Application of the VFS model to experimental data was satisfactory under the condition that actual flow widths are used in the model instead of the total filter width. Predicted and observed sediment trapping efficiencies and infiltration volume fitted very well, with a coefficient of determination (R2) of 0·9 and 0·95, respectively. Regression analyses revealed that the slope and intercept of the regression lines between predicted versus observed infiltration volume and trapping efficiency were not significantly different than the line of perfect agreement with a slope of 1·0 and intercept of 0·0. Copyright © 2001 John Wiley & Sons, Ltd. [source] Acceleration of Cheddar Cheese Lipolysis by Using Liposome-entrapped LipasesJOURNAL OF FOOD SCIENCE, Issue 2 2002E.E. Kheadr ABSTRACT: Two types of lipase (Palatase M and Lipase 50) were encapsulated in liposomes with trapping efficiencies of 35.9 and 40.3%, respectively. The lipases were incorporated into cheese milk at levels of 0.2, 0.5, and 1.0 lipase units/g fat. Treated cheeses had higher moisture and lower protein, fat, and ash contents than the control cheese and they were less firm, but more elastic and cohesive, than the control cheese. Production of free fatty acids was accelerated by the addition of encapsulated enzymes. Cheeses with up to 0.5 lipase unit/g milk fat had slightly better flavor intensities than control cheese. Cheeses with the highest level of Palatase M and Lipase 50 developed a pronounced soapy off-flavor after 2 and 3 mo of ripening, respectively. [source] A bidirectional gene trap construct suitable for T-DNA and Ds -mediated insertional mutagenesis in rice (Oryza sativa L.)PLANT BIOTECHNOLOGY JOURNAL, Issue 5 2004Andrew L. Eamens Summary A construct suitable for genome-wide transfer-DNA (T-DNA) and subsequent transposon-based (Ds) gene trapping has been developed for use in rice (Oryza sativa). This T-DNA/Ds construct contains: Ds terminal sequences immediately inside T-DNA borders for subsequent Ds mobilization; promoterless green fluorescent protein (sgfpS65T) and ,-glucuronidase (uidA) reporter genes, each fused to an intron (from Arabidopsis GPA1 gene) to enable bidirectional gene trapping by T-DNA or Ds; an ampicillin resistance gene (bla) and a bacterial origin of replication (ori) to serve as the plasmid rescue system; an intron-containing hygromycin phosphotransferase gene (hph) as a selectable marker or Ds tracer; and an intron-containing barnase gene in the binary vector backbone (VB) to select against transformants carrying unwanted VB sequences. More than a threefold increase over previously reported reporter gene-based gene trapping efficiencies was observed in primary T-DNA/Ds transformant rice lines, returning an overall reporter gene expression frequency of 23%. Of the plant organs tested, 3.3,7.4% expressed either reporter at varying degrees of organ or tissue specificity. Approximately 70% of the right border (RB) flanking sequence tags (FSTs) retained 1,6 bp of the RB repeat and 30% of the left border (LB) FSTs retained 5,23 bp of the LB repeat. The remaining FSTs carried deletions of 2,84 bp inside the RB or 1,97 bp inside the LB. Transposition of Ds from the original T-DNA was evident in T-DNA/Ds callus lines super-transformed with a transposase gene (Ac) construct, as indicated by gene trap reporter activity and rescue of new FSTs in the resulting double transformant lines. [source] A new linear ion trap mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2002James W. Hager Characteristics of mass selective axial ion ejection from a linear quadrupole ion trap in the presence of an auxiliary quadrupole field are described. Ion ejection is shown to occur through coupling of radial and axial motion in the exit fringing fields of the linear ion trap. The coupling is efficient and can result in extraction of as much as 20% of the trapped ions. This, together with the very high trapping efficiencies, can yield high sensitivity mass spectral responses. The experimental apparatus is based on the ion path of a triple quadrupole mass spectrometer allowing either the q2 collision cell or the final mass analysis quadrupole to be used as the linear trap. Space charge induced distortions of the mass resolved features while using the pressurized q2 linear ion trap occur at approximately the same ion density as reported for conventional three-dimensional ion traps. These distortions are, however, much reduced for the lower pressure linear trap possibly owing to the proposed axial ejection mechanism that leads to ion ejection only for ions of considerable radial amplitude. RF heating due to the high ejection q -value and the low collision frequency may also contribute. Two hybrid RF/DC quadrupole-linear ion trap instruments are described that provide high sensitivity product ion scanning while operated in the linear ion trap mode while also retaining all conventional triple quadrupole scan modes such as precursor ion and neutral loss scan modes. Copyright © 2002 John Wiley & Sons, Ltd. [source] Effectiveness of grass strips in trapping suspended sediments from runoffEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2010Chengzhong Pan Abstract Little information is available concerning the performance of grass strips for erosion control from steep cropland. An experiment was conducted on 5-m-long grass strips with slopes of 3°,15° that were subjected to silt laden runoff and simulated rainfall, to investigate the sediment trapping processes. The grass strips had three treatments including intact grass control (C), no litter (dead grass material covering the soil surface was removed) (NL), and no litter or leaves (only 2,3,cm grass stems and roots were reserved) (NLL). Generally the grass strips had a high effectiveness in trapping sediment from steep cropland runoff. Sediment trapping efficiency (STE) decreased with increasing slope gradient, and even for a 15° slope, STE was still more than 40%. Most sediment deposited in the backwater region before each grass strips. The removal of grass litter or/and leaves had no significant influence on STE. The sediment median size (D50) in inflow was greater than that in outflow, and the difference (,D50) decreased with increasing slope. A positive power relationship between STE and ,D50 can be obtained. Grass strips were more effective in trapping sediments coarser than 10 or 25,µm, but sediments finer than 1,µm were more readily removed from runoff than particles in the range of 2 to approximately 10,µm. Grass litter had less influence on flow velocity than leaves because the deposited sediment partially covered the litter layer. Mean flow velocity and its standard deviation were negatively correlated with STE, and they can help make good estimation of STE. Results from this study should be useful in planting and managing forage grass to effectively conserve soil loss by runoff from steep slopes on the Loess Plateau of China. Copyright © 2010 John Wiley & Sons, Ltd. [source] A 3-D dielectrophoretic filter chipELECTROPHORESIS, Issue 7 2007Ciprian Iliescu Dr. Abstract The paper presents a 3-D filter chip employing both mechanical and dielectrophoretic (DEP) filtration, and its corresponding microfabrication techniques. The device structure is similar to a classical capacitor: two planar electrodes, made from a stainless steel mesh, and bonded on both sides of a glass frame filled with round silica beads. The solution with the suspension of particles flows through both the mesh-electrodes and silica beads filter. The top stainless steel mesh (with openings of 60,,m and wires of 30,,m-thickness) provides the first stage of filtration based on mechanical trapping. A second level of filtration is based on DEP by using the nonuniformities of the electric field generated in the capacitor due to the nonuniformities of the dielectric medium. The filter can work also with DC and AC electric fields. The device was tested with yeast cells (Saccharomyces cerevisae) and achieved a maximal trapping efficiency of 75% at an applied AC voltage of 200,V and a flow rate of 0.1,mL/min, from an initial concentration of cells of 5×105 cells/mL. When the applied frequency was varieted in the range between 20 and 200,kHz, a minimal value of capture efficiency (3%) was notticed at 50,kHz, when yeast cells exhibit negative DEP and the cells are repelled in the space between the beads. [source] The use of riparian vegetated filter strips to reduce river sediment loads: an overestimated control measure?HYDROLOGICAL PROCESSES, Issue 20 2006Gert Verstraeten Abstract The spatially distributed soil erosion and sediment delivery model WATEM/SEDEM was used to simulate the impact of riparian vegetated filter strips (RVFSs) on river sediment delivery at different spatial scales. For a field plot with a straight slope, sediment reduction by the RVFSs is comparable to results obtained through experimental set-ups elsewhere (i.e. >70%). However, at the scale of an entire catchment, sediment reduction is much less (i.e. ±20%) due to (1) overland flow convergence, which reduces the sediment trapping efficiency of an RVFS, and (2) because part of the sediment bypasses the RVFSs through ditches, sewers and road surfaces. These results suggest that, at the catchment scale, RVFSs should be accompanied with other conservation techniques that are more appropriate for reducing river sediment loads, and that also reduce on-site soil erosion. Copyright © 2006 John Wiley & Sons, Ltd. [source] Validation of a vegetated filter strip model (VFSMOD)HYDROLOGICAL PROCESSES, Issue 5 2001Dr Majed Abu-Zreig Abstract Vegetated filter strips (VFS) are designed to reduce sediment load and other pollutants into water bodies. However, adaptation of VFS in the field has been limited owing to lack of data about their efficiency and performance under natural field conditions. A number of models are available that simulate sediment transport and trapping in VFS, but there is a general lack of confidence in VFS models owing to limited validation studies and model limitations that prevent correct application of these models under field conditions. The objective of this study is to test and validate a process-based model (VFSMOD) that simulates sediment trapping in VFS. This model links three submodels: modified Green,Ampt's infiltration, Quadratic overland flow submodel based on kinematic wave approximation and University of Kentucky sediment filtration model. A total of 20 VFS, 2, 5, 10 and 15 m long and with various vegetation covers, were tested under simulated sediment and runoff conditions. The results of these field experiments were used to validate the VFS model. The model requires 25 input parameters distributed over five input files. All input parameters were either measured or calculated using experimental data. The observed sediment trapping efficiencies varied from 65% in the 2-m long VFS to 92% in the 10-m long filters. No increase in sediment removal efficiency was observed at higher VFS length. Application of the VFS model to experimental data was satisfactory under the condition that actual flow widths are used in the model instead of the total filter width. Predicted and observed sediment trapping efficiencies and infiltration volume fitted very well, with a coefficient of determination (R2) of 0·9 and 0·95, respectively. Regression analyses revealed that the slope and intercept of the regression lines between predicted versus observed infiltration volume and trapping efficiency were not significantly different than the line of perfect agreement with a slope of 1·0 and intercept of 0·0. Copyright © 2001 John Wiley & Sons, Ltd. [source] Performance Evaluation of the Scent Transfer UnitÔ (STU-100) for Organic Compound Collection and ReleaseJOURNAL OF FORENSIC SCIENCES, Issue 4 2006Brian A. Eckenrode Ph.D. ABSTRACT: The Scent Transfer UnitÔ (STU-100) is a portable vacuum that uses airflow through a sterile gauze pad to capture a volatiles profile over evidentiary items for subsequent canine presentation to assist law enforcement personnel. This device was evaluated to determine its ability to trap and release organic compounds at ambient temperature under controlled laboratory conditions. Gas chromatography-mass spectrometry (GC-MS) analyses using a five-component volatiles mixture in methanol injected directly into a capture pad indicated that compound release could be detected initially and 3 days after the time of collection. Additionally, 15 compounds of a 39-component toxic organic gaseous mixture (10,1000 parts per billion by volume [p.p.b.v]) were trapped, released, and detected in the headspace of a volatiles capture pad after being exposed to this mixture using the STU-100 with analysis via GC-MS. Component release efficiencies at ambient temperature varied with the analyte; however, typical values of c. 10% were obtained. Desorption at elevated temperatures of reported human odor/scent chemicals and colognes trapped by the STU-100 pads was measured and indicated that the STU-100 has a significant trapping efficiency at ambient temperature. Multivariate statistical analysis of subsequent mass spectral patterns was also performed. [source] Synthesis of [11C- carbonyl]hydroxyureas by a rhodium-mediated carbonylation reaction using [11C]carbon monoxideJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2006Julien Barletta Abstract [11C]Hydroxyurea has been successfully labelled using [11C]carbon monoxide at low concentration. The decay-corrected radiochemical yield was 38±3%, and the trapping efficiency of [11C]carbon monoxide in the order of 90±5%. This synthesis was performed by a rhodium-mediated carbonylation reaction starting with azidotrimethylsilane and the rhodium complex being made in situ by chloro(1,5-cyclooctadiene)rhodium(I) dimer ([Rh(cod)Cl]2) and 1,2- bis(diphenylphosphino)ethane (dppe). (13C)Hydroxyurea was synthesized using this method and the position of the labelling was confirmed by 13C-NMR. In order to perform accurate LC,MS identification, the derivative 1-hydroxy-3-phenyl[11C]urea was synthesized in a 35±4% decay-corrected radiochemical yield. After 13 µA h bombardment and 21 min synthesis, 1.6 GBq of pure 1-hydroxy-3-phenyl[11C]urea was collected starting from 6.75 GBq of [11C]carbon monoxide and the specific radioactivity of this compound was in the order of 686 GBq/µmol (3.47 nmol total mass). [11C]Hydroxyurea could be used in conjunction with PET to evaluate the uptake of this anticancer agent into tumour tissue in individual patients. Copyright © 2006 John Wiley & Sons, Ltd. [source] The design of an on-line semi-preparative LC,SPE,NMR system for trace analysis,MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2005Feng Xu Abstract This paper reports the design of an on-line semi-preparative LC,SPE,NMR system and its use in the structural analysis of mixture components at the 0.02,1% level. The combination provides at least a five fold mass sensitivity increase over that obtained from typical analytical LC,SPE systems and a >30-fold total NMR sensitivity enhancement over analysis by LC,NMR. This is accomplished by using a novel on-line device to store, dilute (1,100-fold) and deliver (at an optimized flow-rate) the isolated component of interest to an SPE trap unit. The SPE unit consists of two cartridges connected in parallel to increase the overall SPE capacity and also to decrease the flow-rate through each trap for enhanced trapping efficiency. As the coupling of semi-preparative LC with NMR (through SPE) is well matched in terms of optimal mass loading for both techniques, only one LC,SPE cycle is required to enrich a 50 µg ml,1 component (1% in a 5 mg ml,1 mixture) for the acquisition of heteronuclear 1H,13C NMR data using a conventional NMR flow probe. Furthermore, analytes at the 0.02% level (,1 µg ml,1) can be studied using 2D 1H NMR techniques if peak cuts from replicate sample injections (,3) are accumulated into the storage/dilution unit and the resulting solution processed by just one SPE trap and elute cycle. Copyright © 2005 John Wiley & Sons, Ltd. [source] Orientation of Culex mosquitoes to carbon dioxide-baited traps: flight manoeuvres and trapping efficiencyMEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2006M. F. Cooperband Abstract., Females of Culex quinquefasciatus Say and Culex tarsalis Coquillet (Diptera: Culicidae) in the host-seeking stage were released and video recorded in three dimensions in a large field wind tunnel as they flew to four kinds of CO2 -baited mosquito traps. The trapping efficiency (number of mosquitoes approaching compared to the number caught) was determined for each trap type. The Encephalitis Virus Surveillance (EVS), Mosquito Magnet Freedom (MMF) and Mosquito Magnet Liberty (MML) traps captured only 13,16% of approaching Cx. quinquefasciatus females, whereas the Mosquito Magnet-X (MMX) trap captured 58%. Similar results were obtained for Cx. tarsalis. Orientation behaviour and flight parameters of mosquitoes approaching the four traps were compared. Mosquitoes spent the most time orienting to the EVS trap. Flight speed decreased as mosquitoes entered the vicinity of each trap and a large portion of their time was spent within 30 cm downwind of the traps. Flights became highly tortuous downwind of the poorly performing traps and just upwind of the MMX trap. Differences between traps and possible explanations for the superior performance of the MMX trap are considered. [source] Fine structure of the stability diagram and the amplitude of ion oscillation within hyperboloidal mass spectrometersRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2002Ernst P. Sheretov This article shows that the dependence of the amplitude of ion oscillation within a hyperboloidal mass spectrometers (HMS) as a function of working point location on the stability diagram (in this case all working points lie at one scan line) exhibits a structure with spikes: the amplitude decreases drastically in some points and these dips look like ,reversed spikes'. It is shown that the dips appear at particular values of the stability parameter, ,0, that correspond to intersections of the scan line with lines of parametric resonances (quasi-stability lines) described by us previously. This effect governs the trapping efficiency of ions injected into a radio-frequency ion trap from an external source. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||