packing

New column packing resists hydrolysis

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New column packing resists hydrolysis by Stephen Stinson.

Hydrolytically stable, C 18 -alkylated silica gel has been developed for use as packing in high-performance liquid chromatography (HPLC) columns by chemists at the University of Delaware, Newark [ Anal Chem. , 65, 822 (1993)]. The material enable analyses to be made very high- and low-pH solutions with high selectivity minimal column deterioration. alkylation method may also provide same benefits when applied interiors capillaries capillary zone electrophoresis. Research Corp. Technologies (RCT). Tucson, Ariz., patents on technology, which firm will license behalf university. Managers RCT suggest that technology useful making crack-resistant optical fibers. Analytical chemistry professor Mary J. Wirth graduate student Hafeez O. Fatunmbi alkylate stirring it 24 hours a solution n -propyland -octadecyltrichlorosilane -hexadecane solvent. This results dense surface but giv…

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Observations of seismic reflections from variations in grain packing

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Observations of seismic reflections from variations in grain packing by Donald H. Sherlock, Brian Evans.

Summary Seismic physical modelling experiments with unconsolidated sands have shown that it is possible to record a seismic reflection from layer boundary where there are only slight changes in material velocity and density. Furthermore, reflections been recorded the interface of two sand packages different average grain sizes but equal density velocity. This suggests combination at produces acoustic impedance contrast required for reflection, which provocative statement challenges need separate layers impedances.

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Opener, packer wheel and packing force effects on crop emergence and yield of direct seeded wheat, canola and field peas

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Opener, packer wheel and packing force effects on crop emergence and yield of direct seeded wheat, canola and field peas by A. M. Johnston, G. P. Lafond, William E. May, G. L. Hnatowich, G. E. Hultgreen.

An understanding of the effects different opener designs and on-row packing force would help producers in their selection appropriate direct seeding implement options for soil conditions. A field trial was conducted at three locations (Indian Head, Sylvania Watrous) Saskatchewan from 1997 to 1999 evaluate effect opener-packer design (spoon-steel V packer; spoon-flat rubber paired row-steel row-flat sweep-pneumatic tire) combination with a range forces [0, 333, 549, 746, 1000 Newton (N) per press wheel] on crop emergence grain yield seeding. The differences observed between combinations this study varied by less than 10% yield, were almost always associated not packer type. Despite variable results, there tendency higher pea wheat sweep + tire compared other types those that tended be drier spring. Also, greater Indian when heavy-textured site had high moisture conditions responses years among crops. Generally, 333 N wheel provided adequate across environmental encountered study, regardless combination. In 1997, 5% more seedlings emerged some amount no packing. Relative check, resulted 13% location-by-year combinations, 9% 1998. However, canola excessive (i.e., two highest vs. lower forces) 11 fewer m -2 1999. pressure conditions, only negatively influencing canola, yield. Key words: Furrow opener, force, emergence, seeding, zero till

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Lipid hydrolyses catalyzed by pancreatic cholesterol esterase. Regulation by substrate and product phase distribution and packing density

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Lipid hydrolyses catalyzed by pancreatic cholesterol esterase. Regulation by substrate and product phase distribution and packing density by Santhoor G. Bhat, Howard L. Brockman.

The role of oleic acid in the regulation hydrolysis cholesteryl oleate lipid films at air–buffer interface was investigated by using initial rate techniques. A small quantity enzyme is rapidly adsorbed to substrate-containing films; however, a much greater, although slower, adsorption occurs if present. constant for slow independent phase distribution but markedly dependent upon both concentration head groups and acyl chain packing density film. Adsorption controlled two ionizable groups, one which may be carboxyl group acid. In contrast adsorption, catalysis surface excess pH between 5.5 7.5 relatively specific substrate monolayer phase. second-order constants interfacial layer double-layer are 27 2 cm2 s-1 fmol-1. These results indicate that occur functionally. not physically, distinct sites on protein. product, acid, constitutes form product activation presumably helps keep it during intraluminal fat digestion. catalytic properties suggest specificities determined cholesterol esterase complex reaction systems largely reflect availability appropriate physical state lipid-water interface.

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APPROXIMATION ALGORITHMS FOR MULTIPLE STRIP PACKING AND SCHEDULING PARALLEL JOBS IN PLATFORMS

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APPROXIMATION ALGORITHMS FOR MULTIPLE STRIP PACKING AND SCHEDULING PARALLEL JOBS IN PLATFORMS by Marin Bougeret, Pierre-François Dutot, Klaus Jansen, Christina Robenek, Denis Trystram.

We consider two strongly related problems, multiple strip packing and scheduling parallel jobs in platforms. In the first one we are given a list of n rectangles with heights widths bounded by N strips unit width infinite height. The objective is to find nonoverlapping orthogonal without rotations all into minimizing maximum height used. problem instead rectangles, i.e., allowed cut vertically may have target areas different size, called A platform P ℓ collection m processors running at speed s minimize makespan, latest finishing time job.

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Granular Packing under Vibration

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Granular Packing under Vibration by Eric Clément.

Granular assemblies under vibration exhibit a very rich phenomenology. The apparent behavior is reminiscent of usual solid, liquid or fluid states. Using minimal amount concepts and crude representation local granular interactions, we discuss the emergence specific phenomenons such as fluidization, convection, heaping, sub-harmonic instability Faraday instability.

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