Fluid dynamics of packed columns principles of the fluid dynamic design of columns for gas/liquid and liquid/liquid systems

CERN Document Server

Mackowiak, Jerzy

2010-01-01

This book describes the basic design principles of columns equipped with modern lattice packings and structured packed beds, as generally used in industry. It provides support to engineers as well as graduate students in their daily design work.

Super/subcritical fluid chromatography with packed columns: state of the art and applications

Directory of Open Access Journals (Sweden)

Carla Grazieli Azevedo da Silva

2014-07-01

Full Text Available Separations using supercritical fluid chromatography (SFC with packed columns have been re-discovered and explored in recent years. SFC enables fast and efficient separations and, in some cases, gives better results than high performance liquid chromatography (HPLC. This paper provides an overview of recent advances in SFC separations using packed columns for both achiral and chiral separations. The most important types of stationary phases used in SFC are discussed as well as the most critical parameters involved in the separations and some recent applications.

Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow

NARCIS (Netherlands)

Roes, A.W.M.; van Swaaij, Willibrordus Petrus Maria

1979-01-01

Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow, a promising new countercurrent operation, was evaluated using residence time distribution (RTD) experiments. The column was packed with dumped Pall rings, the gas phase was air at ambient conditions and the solid

Rice Husk Packed Bed Column Reactor To Remove Cadmium From Landfill Leachate

Directory of Open Access Journals (Sweden)

Monik Kasman

2014-06-01

Full Text Available The landfill leachate can be a major problem due to large variability of high organic, inorganic, heavy metal content and toxicity characteristics from landfill leachate such as  cadmium. Thus, this study was aimed to observe the application of rice husk packed bed column to reduce cadmium from landfill leachate. Experiment was conducted in gravity down flow system by pumping landfill leachate into packed bed column. The effect of influent flow rate to adsorption capacity was studied by varying flow rate (5 mL/min and 10 mL/min. The effluent-influent concentration ratio Ce/C0 (% as a function of throughput volume (L was used to represent the breakthrough curve in column systems. Result shows that the flow rate of 5 mL/min was favorable to achieve higher removal rates with the percentage of cadmium was 57 %. At breakthrough time, the cadmium effluent concentration reached on 0.01 mg/l for both of flow rate.ABSTRAKLindi yang dihasilkan dari TPA (Tempat Pembuangan Akhir menimbulkan permasalahan lingkungan karena kandungan pencemarnya meliputi material organik, material anorganik, logam dan material beracun. Salah satu logam berat yang terdapat dalam lindi tersebut adalah kadmium. Penelitian ini bertujuan untuk mereduksi kadmium dalam lindi dengan menggunakan sekam padi yang diinstal dalam packed bed column. Lindi dipompakan dari tangki penampung lindi ke dalam packed bed column dan dialirkan dari atas ke bawah kolom secara gravitasi. Fokus pada penelitian ini adalah pengaruh laju alir influen terhadap kapasitas adsorpsi. Dimana lindi dialirkan dengan laju alir 5 mL/menit dan 10 mL/menit. Kurva breakthrough (titik jenuh kolom dipresentasikan oleh hubungan antara rasio konsentrasi efluen-influen Ce/C0 (% dan jumlah aliran lindi yang diolah dalam kolom. Hasil eksperimen menunjukkan bahwa persentase reduksi tertinggi dicapai pada laju alir 5 mL/menit yaitu 57%. Waktu jenuh kedua laju alir (5 mL/menit dan 10 mL/menit tercapai saat konsentrasi efluen

Hydrodynamic behaviour of a gas—solid counter-current packed column at trickle flow

NARCIS (Netherlands)

Roes, A.W.M.; van Swaaij, Willibrordus Petrus Maria

1979-01-01

Trickle flow of a more or less fluidized catalyst through a packed column is a promising new gas—solid counter-current operation. The hydrodynamic, behaviour of such a column, filled with dumped PALL rings, has been investigated, while some results have been obtained with RASCHIG rings and

Improvement for the design of packed moving bed adsorption column

International Nuclear Information System (INIS)

Xiao Wei

2014-01-01

The problems needed to pay attention to in the physical design of packed moving bed adsorption column were presented. The design of key parts such as the inlet and outlet of liquid phase and gas phase were improved. The expected effect was achieved by the improvement. (author)

Adsorption of zinc ions on bone char using helical coil-packed bed columns and its mass transfer modeling

DEFF Research Database (Denmark)

Moreno-Pérez, J.; Bonilla-Petriciolet, A.; Rojas-Mayorga, C. K.

2016-01-01

This study reports the assessment of helical coil-packed bed columns for Zn2+ adsorption on bone char. Zn2+ adsorption breakthrough curves have been obtained using helical coil columns with different characteristics and a comparison has been conducted with respect to the results of straight fixed-bed...... columns. Results showed that the helical coil adsorption columns may offer an equivalent removal performance than that obtained for the traditional packed bed columns but using a compact structure. However, the coil diameter, number of turns, and feed flow appear to be crucial parameters for obtaining...... the best performance in this packed-bed geometry. A mass transfer model for a mobile fluid flowing through a porous media was used for fitting and predicting the Zn2+ breakthrough curves in helical coil bed columns. Results of adsorbent physicochemical characterization showed that Zn2+ adsorption on bone...

Hydrodynamic impact of particle shape in slurry packed liquid chromatography columns

DEFF Research Database (Denmark)

Lottes, F.; Arlt, W.; Minceva, M.

2009-01-01

We report on a series of flow velocity and efficiency profiles, which were measured across the cross section of preparative chromatographic columns packed with different stationary phase materials using computed tomography. It is shown that this non-invasive technique is very useful for visualiza...

Analysis of packing microstructure and wall effects in a narrow-bore ultrahigh pressure liquid chromatography column using focused ion-beam scanning electron microscopy.

Science.gov (United States)

Reising, Arved E; Schlabach, Sabine; Baranau, Vasili; Stoeckel, Daniela; Tallarek, Ulrich

2017-09-01

Column wall effects are well recognized as major limiting factor in achieving high separation efficiency in HPLC. This is especially important for modern analytical columns packed with small particles, where wall effects dominate the band broadening. Detailed knowledge about the packing microstructure of packed analytical columns has so far not been acquired. Here, we present the first three-dimensional reconstruction protocol for these columns utilizing focused ion-beam scanning electron microscopy (FIB-SEM) on a commercial 2.1mm inner diameter×50mm length narrow-bore analytical column packed with 1.7μm bridged-ethyl hybrid silica particles. Two sections from the packed bed are chosen for reconstruction by FIB-SEM: one from the bulk packing region of the column and one from its critical wall region. This allows quantification of structural differences between the wall region and the center of the bed due to effects induced by the hard, confining column wall. Consequences of these effects on local flow velocity in the column are analyzed with flow simulations utilizing the lattice-Boltzmann method. The reconstructions of the bed structures reveal significant structural differences in the wall region (extending radially over approximately 62 particle diameters) compared to the center of the column. It includes the local reduction of the external porosity by up to 10% and an increase of the mean particle diameter by up to 3%, resulting in a decrease of the local flow velocity by up to 23%. In addition, four (more ordered) layers of particles in the direct vicinity of the column wall induce local velocity fluctuations by up to a factor of three regarding the involved velocity amplitudes. These observations highlight the impact of radial variations in packing microstructure on band migration and column performance. This knowledge on morphological peculiarities of column wall effects helps guiding us towards further optimization of the packing process for analytical

[Analysis of hydrogen isotopes by gas chromatography using a MnCl2 coated γ-Al2O3 capillary packed column].

Science.gov (United States)

Chen, Ping; Fu, Xiaolong; Hu, Peng; Xiao, Chengjian; Ren, Xingbi; Xia, Xiulong; Wang, Heyi

2017-07-08

The conventional packed column gas chromatographic analysis of hydrogen isotopes has low column efficiency, broad peak and long retention time. In this work, a γ -Al 2 O 3 with MnCl 2 coated capillary packed column was tested at cryogenic temperature. The systematic column efficiency analysis and the hydrogen isotopes analytical technique research had been carried out. The results showed that, the γ -Al 2 O 3 with MnCl 2 coating could greatly improve the surface degree of order, pore structure and adsorption properties. Also the o -H 2 peak and p -H 2 peak were eluted in a single area. The γ -Al 2 O 3 with MnCl 2 coating was packed into a 0.53 mm inner diameter and 1.0 m long fused silica capillary column. It had a good linear relationship used this column with thermal conductivity detector (TCD) to detect the volume concentrations of hydrogen isotopes from 1 to 10 mL/L, and the relative error was less than 5% for low concentration sample testing. For H 2 , HD and D 2 , the retention times can be shortened to 39, 46 and 60 s, respectively. The limits of detection were reduced to 0.046, 0.067 and 0.072 mL/L, respectively. Compared with conventional packed column, capillary packed column had sharper peak form, higher separation degree of adjacent components, shorter retention time and lower detection limits. The above results indicate that the capillary packed column with TCD detector can be used for fast detection of low concentration of hydrogen isotopes and their online analysis.

Dissolved oxygen removal in a column packed with catalyst

International Nuclear Information System (INIS)

Lee, Han Soo; Chung, Hong Suk; Cho, Young Hyun; Ahn, Do Hee; Kim, Eun Kee

1996-01-01

The dissolved oxygen removed by H 2 -O 2 reaction in column packed with various catalysts was examined. The catalysts employed were the prepared polymeric catalyst, platinum on activated carbon, and Lewatit OC-1045 which is available commercially. The column experiments with the prepared polymeric catalyst showed the dissolved oxygen reduced to 35 ppb which is below the limit in feel water of power plants. This implies the likely application of the prepared catalyst for practical use. The activated carbon required the pre-treatment for the removed of dissolved oxygen, since the surface of activated carbon contains much oxygen adsorbed initially. The Lewatit catalyst exposed the best performance, however, the aged one showed the gradual loss of catalytic activity due to degradation of resin catalyst. 14 refs., 6 figs., 2 tabs. (author)

Determination of betaine, l-carnitine, and choline in human urine using a self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

Science.gov (United States)

Wei, Dan; Liu, Junwei; Guo, Ming; Zhu, Yan

2017-11-01

A simple method for the determination of betaine, l-carnitine, and choline in human urine was developed based on column-switching ion chromatography coupled with nonsuppressed conductivity detection by using a self-packed column. A pretreatment column (50 mm × 4.6 mm, id) packed with poly(glycidyl methacrylate-divinylbenzene) microspheres was used for the extraction and cleanup of analytes. Chromatographic separation was achieved within 10 min on a cationic exchange column (150 mm × 4.6 mm, id) using maleic anhydride modified poly(glycidyl methacrylate-divinylbenzene) as the particles for packing. The detection was performed by ion chromatography with nonsuppressed conductivity detection. Parameters including column-switching time, eluent type, flow rates of eluent, and interfering effects were optimized. Linearity (r 2 ≥ 0.99) was obtained for the concentration range of 0.50-100, 0.75-100, and 0.25-100 μg/mL for betaine, l-carnitine, and choline, respectively. Detection limits were 0.12, 0.20, and 0.05 μg/mL for betaine, l-carnitine, and choline, respectively. The intra- and interday accuracy and precision for all quality controls were within ±10.11%. Satisfactory recovery was observed between 92.5 and 105.0%. The validated method was successfully applied for the determination of betaine, l-carnitine, and choline in urine samples from healthy people. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physical properties and structure of fine core-shell particles used as packing materials for chromatography Relationships between particle characteristics and column performance.

Science.gov (United States)

Gritti, Fabrice; Leonardis, Irene; Abia, Jude; Guiochon, Georges

2010-06-11

The recent development of new brands of packing materials made of fine porous-shell particles, e.g., Halo and Kinetex, has brought great improvements in potential column efficiency, demanding considerable progress in the design of chromatographic instruments. Columns packed with Halo and Kinetex particles provide minimum values of their reduced plate heights of nearly 1.5 and 1.2, respectively. These packing materials have physical properties that set them apart from conventional porous particles. The kinetic performance of 4.6mm I.D. columns packed with these two new materials is analyzed based on the results of a series of nine independent and complementary experiments: low-temperature nitrogen adsorption (LTNA), scanning electron microscopy (SEM), inverse size-exclusion chromatography (ISEC), Coulter counter particle size distributions, pycnometry, height equivalent to a theoretical plate (HETP), peak parking method (PP), total pore blocking method (TPB), and local electrochemical detection across the column exit section (LED). The results of this work establish links between the physical properties of these superficially porous particles and the excellent kinetic performance of columns packed with them. It clarifies the fundamental origin of the difference in the chromatographic performances of the Halo and the Kinetex columns. Copyright 2010 Elsevier B.V. All rights reserved.

Modeling chromatographic columns. Non-equilibrium packed-bed adsorption with non-linear adsorption isotherms

NARCIS (Netherlands)

Özdural, A.R.; Alkan, A.; Kerkhof, P.J.A.M.

2004-01-01

In this work a new mathematical model, based on non-equilibrium conditions, describing the dynamic adsorption of proteins in columns packed with spherical adsorbent particles is used to study the performance of chromatographic systems. Simulations of frontal chromatography, including axial

Aromatically enhanced pear distillates from blanquilla and conference varieties using a packed column.

Science.gov (United States)

Arrieta-Garay, Yanine; García-Llobodanin, Laura; Pérez-Correa, José Ricardo; López-Vázquez, Cristina; Orriols, Ignacio; López, Francisco

2013-05-22

Pear distillates are generally produced from the Bartlett variety because of its rich aroma. In this study, a chemical and sensorial comparative examination of pear distillates from the three main varieties grown in Spain (Bartlett, Blanquilla, and Conference) using two distillation systems (copper Charentais alembic and packed column) was undertaken. Volatile compounds were identified by gas chromatography to differentiate the spirits according to pear variety and distillation method. The Bartlett distillates from both distillation systems possessed higher ethyl ester and acetate and lower cis-3-hexen-1-ol and 1-hexanol concentrations. Despite these differences, a sensory analysis panel could distinguish only the Bartlett alembic distillate from the alembic distillates of the other varieties. In contrast, the panel rated the packed-column distillates equally. Therefore, less aromatic pear varieties can be used to produce distillates with aromatic characteristics similar to those of the Bartlett variety if a suitable distillation process is used.

Comparative study of the performance of columns packed with several new fine silica particles. Would the external roughness of the particles affect column properties?

Science.gov (United States)

Gritti, Fabrice; Guiochon, Georges

2007-09-28

We measured and compared the characteristics and performance of columns packed with particles of five different C(18)-bonded silica, 3 and 5 microm Luna, 3 microm Atlantis, 3.5 microm Zorbax, and 2.7 microm Halo. The average particle size of each material was derived from the SEM pictures of 200 individual particles. These pictures contrast the irregular morphology of the external surface of the Zorbax and Halo particles and the smooth surface of the Luna and Atlantis particles. In a wide range of mobile phase velocities (from 0.010 to 3 mL/min) and at ambient temperature, we measured the first and second central moments of the peaks of naphthalene, insulin, and bovine serum albumin (BSA). These moments were corrected for the contributions of the extra-column volumes to calculate the reduced HETPs. The C-terms of naphthalene and insulin are largest for the Halo and Zorbax materials and the A-term smallest for the Halo-packed column. The Halo column performs the best for the low molecular weight compound naphthalene (minimum reduced HETP, 1.4) but is not as good as the Atlantis or Luna columns for the large molecular weight compound insulin. The Zorbax column is the least efficient column because of its large C-term. The lowest sample diffusivity through these particles, alone, does not account for the results. It is most likely that the roughness of the external surface of the Halo and Zorbax particles limit the performance of these columns at high flow rates generating an unusually high film mass transfer resistance.

Flooding characteristics of Goodloe packing

International Nuclear Information System (INIS)

Begovich, J.M.; Watson, J.S.

1976-08-01

Experimental flooding data for the countercurrent flow of air and water in a 7.62-cm-diam glass column filled with Goodloe packing were compared with a correlation reported by the packing manufacturer. Flooding rates observed in this study were as low as one-half those predicted by the correlation. Rearranging the packing by inverting the column and removing some packing segments yielded results similar to the correlation for liquid-to-gas (L/G) mass flow rate ratios greater than 10, but the experimental flooding curve fell significantly below the correlation at lower L/G ratios. When the column was repacked with new packing, the results were essentially the same as those obtained in the inverted column. Thus, it is believed that a carefully packed column is more likely to yield flooding rates similar to those obtained in the new or inverted columns rather than rates predicted by the original correlation

Effect of oxygen on ethanol fermentation in packed-bed tapered-column reactor

Energy Technology Data Exchange (ETDEWEB)

Hamamci, H.; Ryu, D.D.Y.

1988-07-01

In ethanol production with immobilized yeast a major problem is the provision of nutrients to these highly concentrated cells. O/sub 2/ being one of the nutrients of utmost importance to yeast cells, was fed into a column packed with beads with a cell loading of more than 40 g/l. Since addition of large volume of air or O/sub 2/ to a cylindrical column reactor would aggravate the problems of pressure build up and channelling caused by the evolving CO/sub 2/ gas, a tapered-column reactor and pulsed flow of oxygen gas was used. The supplement of O/sub 2/ gas to the tapered column increased the productivity from 21.1 g ethanol x (l gel x h)/sup -1/ to 26.7 g x (l gelxh)/sup -1/, when the ethanol concentration at the outlet was about 80 g/l. The yield coefficient of ethanol was also increased from 0.41 g ethanol/g glucose to 0.43 after O/sub 2/ supplement was started. The effects of frequency and duration of O/sub 2/ supplement were also determined.

Height determination at the transfer unit in isotopic distillation of hydrogen on type B7 ordered column packing

International Nuclear Information System (INIS)

Pop, F.; Croitoru, C.; Peculea, M.

2001-01-01

Owing to the low pressure drop implied by ordered column packings these are often utilized for vacuum distillations and separation of mixtures in which the important component occurs at a very low concentration, as for instance is the case of water, deuterium or oxygen isotopic distillation. The paper presents a model for determination of the height of transfer unit (HTU) in the hydrogen isotopic distillation installation, equipped with ordered column packing of B7 type. The computed values for HUT based on the analogy between heat, moment and mass transfer, were compared with the experimental data

Multiple steady states detection in a packed-bed reactive distillation column using bifurcation analysis

DEFF Research Database (Denmark)

Ramzan, Naveed; Faheem, Muhammad; Gani, Rafiqul

2010-01-01

A packed reactive distillation column producing ethyl tert-butyl ether from tert-butyl alcohol and ethanol was simulated for detection of multiple steady states using Aspen Plus®. A rate-based approach was used to make the simulation model more realistic. A base-case was first developed and fine...

Two-Phase Flow in Packed Columns and Generation of Bubbly Suspensions for Chemical Processing in Space

Science.gov (United States)

Motil, Brian J.; Green, R. D.; Nahra, H. K.; Sridhar, K. R.

2000-01-01

For long-duration space missions, the life support and In-Situ Resource Utilization (ISRU) systems necessary to lower the mass and volume of consumables carried from Earth will require more sophisticated chemical processing technologies involving gas-liquid two-phase flows. This paper discusses some preliminary two-phase flow work in packed columns and generation of bubbly suspensions, two types of flow systems that can exist in a number of chemical processing devices. The experimental hardware for a co-current flow, packed column operated in two ground-based low gravity facilities (two-second drop tower and KC- 135 low-gravity aircraft) is described. The preliminary results of this experimental work are discussed. The flow regimes observed and the conditions under which these flow regimes occur are compared with the available co-current packed column experimental work performed in normal gravity. For bubbly suspensions, the experimental hardware for generation of uniformly sized bubbles in Couette flow in microgravity conditions is described. Experimental work was performed on a number of bubbler designs, and the capillary bubble tube was found to produce the most consistent size bubbles. Low air flow rates and low Couette flow produce consistent 2-3 mm bubbles, the size of interest for the "Behavior of Rapidly Sheared Bubbly Suspension" flight experiment. Finally the mass transfer implications of these two-phase flows is qualitatively discussed.

Effect of the structured packing height on efficiency of freons mixture separation in a large-scale model of distillation column

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Pavlenko Aleksandr

2017-01-01

Full Text Available Results of experimental studies of heat-and-mass transfer and hydrodynamic processes at distillation on a regular packing are presented. The mixture of freons R114–R21 at the pressure of 0.3 MPa was used as a working mixture. The mixture was separated on the Mellapak 350Y structured packing with the diameter of 0.9 m under the conditions of complete reflux (L/V = 1 at different packing heights. A specially designed liquid distributor with a possibility to change the density and pattern of drip points was used to irrigate the packing. The experimental data on the efficiency of mixture separation (height of transfer unit HTU and distribution of the local flow rate density over the column cross-section were compared. It is shown that an increase in the height of the structured packing from 2.1 m to 4.0 m leads to a significant decrease in the efficiency of mixture separation in the distillation column.

Application of a Fast Separation Method for Anti-diabetics in Pharmaceuticals Using Monolithic Column: Comparative Study With Silica Based C-18 Particle Packed Column.

Science.gov (United States)

Hemdan, A; Abdel-Aziz, Omar

2018-04-01

Run time is a predominant factor in HPLC for quality control laboratories especially if there is large number of samples have to be analyzed. Working at high flow rates cannot be attained with silica based particle packed column due to elevated backpressure issues. The use of monolithic column as an alternative to traditional C-18 column was tested for fast separation of pharmaceuticals, where the results were very competitive. The performance comparison of both columns was tested for separation of anti-diabetic combination containing Metformin, Pioglitazone and Glimepiride using Gliclazide as an internal standard. Working at high flow rates with less significant backpressure was obtained with the monolithic column where the run time was reduced from 6 min in traditional column to only 1 min in monolithic column with accepted resolution. The structure of the monolith contains many pores which can adapt the high flow rate of the mobile phase. Moreover, peak symmetry and equilibration time were more efficient with monolithic column.

Kinetic investigation of narrow-bore columns packed with prototype sub-2 μm superficially porous particles with various shell thickness.

Science.gov (United States)

Gritti, Fabrice; Omamogho, Jesse; Guiochon, Georges

2011-10-07

The recent successful breakthrough of sub-3 μm shell particles in HPLC has triggered considerable research efforts toward the design of new brands of core-shell particles. We investigated the mass transfer mechanism of a few analytes in narrow-bore columns packed with prototype 1.7 μm shell particles, made of 1.0, 1.2, and 1.4 μm solid nonporous cores surrounded by porous shells 350, 250, and 150 nm thick, respectively. Three probe solutes, uracil, naphthalene, and insulin, were chosen to assess the kinetic performance of these columns. Inverse size exclusion chromatography, peak parking experiments, and the numerical integration of the experimental peak profiles were carried out in order to measure the external, internal, and total column porosities, the true bulk diffusion coefficients of these analytes, the height equivalent to a theoretical plate, the longitudinal diffusion term, and the trans-particle mass transfer resistance term. The residual eddy diffusion term was measured by difference. The results show the existence of important trans-column velocity biases (7%) possibly due to the presence of particle multiplets in the slurry mixture used during the packing process. Our results illustrates some of the difficulties encountered by scientists preparing and packing shell particles into narrow-bore columns. Copyright © 2011 Elsevier B.V. All rights reserved.

Hydrogen extraction from Pb-17Li: results with a 800 mm high packed column

International Nuclear Information System (INIS)

Alpy, N.; Terlain, A.; Lorentz, V.

2000-01-01

Within the framework of the studies carried out for the development of a gas-liquid alloy contactor for the extraction of hydrogen from Pb-17Li, the behaviour of a 800 mm high packed column has been investigated on the Melodie loop. The previous contactor technology, a structured packing supplied by the Sulzer Company, has been retained since it had shown satisfying efficiency, likely due to the beneficial effect, on the mass transfer, of the liquid flow division that it involves. The best results of the present study have been achieved via a reduction of the liquid load on the packing: an efficiency of up to 30% was reached at 673 K for an inlet hydrogen pressure in Pb-17Li of 1000 Pa. The impact of the hydrogen pressure in the inlet Pb-17Li flow and on the extraction efficiency has been experimentally assessed: this study allowed us to evaluate the potential of the process in terms of packing height. Finally, a future experimental facility, which should allow us to observe the hydraulic behaviour of liquid mercury (simulating Pb-17Li) on the packing is presented

Analysis of the Conditions for the Inception of Natural Pulsing Flow in Cocurrent Packed Columns

Czech Academy of Sciences Publication Activity Database

Akramov, T. A.; Stavárek, Petr; Jiřičný, Vladimír; Staněk, Vladimír

2008-01-01

Roč. 47, č. 19 (2008), s. 7424-7432 ISSN 0888-5885 R&D Projects: GA MPO FT-TA/039 Institutional research plan: CEZ:AV0Z40720504 Keywords : natural pulsing flow * cocurrent flow * packed columns Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.895, year: 2008

Holdup of O/W emulsion in a packed column for liquid membrane separation of hydrocarbon; Tankasuiso no ekimaku bunri ni okeru jutento nai no emarushon horudo appu

Energy Technology Data Exchange (ETDEWEB)

Egashira, R.; Sugimoto, T.; Kawasaki, J. [Tokyo Inst. of Technology, Tokyo (Japan). Faculty of Engineering

1993-07-10

Liquid membrane separation of hydrocarbon is an energy saving separation method that is expected of practical use. If the method uses a packed column, the holdup of O/W emulsion affects the effective contact area and residence time of the emulsion. Therefore, this paper describes an attempt to correlate the dynamic emulsion holdup in a packed column in liquid membrane separation of hydrocarbon with property values of the emulsion and external oil phase, and operation variables. The experiment used a mixture of toluene + n - heptane + n - decane for oil phase in the O/W emulsion and saponin aqueous solution for liquid phase (liquid membrane phase). The packed column with an inner diameter of 37 mm used stainless steel McMahon packing. As a result of the experiment, the dynamic emulsion holdup showed a correlation according to the Reynolds number and Galilei number, regardless of whether the emulsion permeates the liquid membrane. The correlation made it possible to estimate in a simple manner the emulsion holdup in the packed column when this separation method is used. 5 refs., 3 figs., 3 tabs.

Effects of the gas-liquid ratio on the optimum catalyst quantity for the CECE process with a homogeneously packed LPCE column

International Nuclear Information System (INIS)

Sugiyama, T.; Ushida, A.; Yamamoto, I.

2008-01-01

In order to improve the separative performance of a combined electrolysis catalytic exchange (CECE) process, we have carried out experimental studies on hydrogen isotope separation by a CECE process using a liquid phase catalytic exchange (LPCE) column of trickle-type packed beds. Two types of trickle beds were tested in our previous study. One was the layered bed, where layers of Kogel catalysts and Dixon gauze rings were alternately filled in the column. The other was the homogeneous bed, where Kogel catalysts and Dixon gauze rings were homogeneously mixed and filled in the column. We found that (1) the homogeneously packed bed was more efficient than the layered packed bed, and (2) the catalyst quantity was optimal, which resulted in the highest separative performance. In this study, the effect of the gas-liquid ratio (G/L) on the optimum catalyst quantity was studied experimentally in a homogeneously packed bed. When the value of G/L was 1.7, total separation factors were relatively small and the optimum catalyst quantity could not be determined. On the other hand, when the values of G/L were 0.9 and 0.7, the values of the total separation factors had maximums and the optimal quantities of the catalyst were clearly obtained

A stochastic view on column efficiency.

Science.gov (United States)

Gritti, Fabrice

2018-03-09

A stochastic model of transcolumn eddy dispersion along packed beds was derived. It was based on the calculation of the mean travel time of a single analyte molecule from one radial position to another. The exchange mechanism between two radial positions was governed by the transverse dispersion of the analyte across the column. The radial velocity distribution was obtained by flow simulations in a focused-ion-beam scanning electron microscopy (FIB-SEM) based 3D reconstruction from a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 particles. Accordingly, the packed bed was divided into three coaxial and uniform zones: (1) a 1.4 particle diameter wide, ordered, and loose packing at the column wall (velocity u w ), (2) an intermediate 130 μm wide, random, and dense packing (velocity u i ), and (3) the bulk packing in the center of the column (velocity u c ). First, the validity of this proposed stochastic model was tested by adjusting the predicted to the observed reduced van Deemter plots of a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 fully porous particles (FPPs). An excellent agreement was found for u i  = 0.93u c , a result fully consistent with the FIB-SEM observation (u i  = 0.95u c ). Next, the model was used to measure u i  = 0.94u c for 2.1 mm × 100 mm column packed with 1.6 μm Cortecs-C 18 superficially porous particles (SPPs). The relative velocity bias across columns packed with SPPs is then barely smaller than that observed in columns packed with FPPs (+6% versus + 7%). u w =1.8u i is measured for a 75 μm × 1 m capillary column packed with 2 μm BEH-C 18 particles. Despite this large wall-to-center velocity bias (+80%), the presence of the thin and ordered wall packing layer has no negative impact on the kinetic performance of capillary columns. Finally, the stochastic model of long-range eddy dispersion explains why analytical (2.1-4.6 mm i.d.) and capillary (columns can all be

Effect of Promoter Concentration on CO2 Separation Using K2CO3 With Reactive Absorption Method in Reactor Packed Column

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Monde Junety

2018-01-01

Full Text Available The presence of carbon dioxide (CO2 in the gas is not expected because CO2 can reduce heating value and CO2 is the major emission contributor into the atmosphere. Various separation technologies can be used to reduce CO2 content and improve quality of gas. Chemical or reactive absorption is most widely used because it provides higher removal rate. This paper will study the effect of the addition di ethanolamine (DEA concentration into aqueous 30wt.% potassium carbonate(K2CO3 with reactive absorption method in a reactor packed column at temperature from 40°C to 80°C, DEA concentration range of (1% - 3% and absorbent flow rate (0.5, 0.75 and 1 L. min1. Contacting the gas and absorbent are countercurrent flow in packed column with 1.5 m high and 50 mm in diameter. The absorption column was randomly packed with a packing material raschig rings 5 mm in diameter. The CO2 loading in the liquid samples was determined by titration. It is found that the best result of CO2 loading is 0.065594 mole/mole K2CO3 and CO2 removal 28%. The result show that the loading capacity (mole CO2/mole K2CO3 and CO2 removal increased with the increase of DEA concentration.

ETHANOL DEHYDRATION IN PACKED DISTILLATION COLUMN USING GLYCEROL AS ENTRAINER: EXPERIMENTS AND HETP EVALUATION

Directory of Open Access Journals (Sweden)

W. L. R. Souza

Full Text Available Abstract The ethanol-water separation is very important because ethanol is widely applied in the chemical industry and its use as a fuel can reduce the pollution emitted to the air. However, anhydrous ethanol production using conventional distillation is impossible, at atmospheric pressure, due to the presence of an azeotrope. In the present work, experimental tests were carried out in order to evaluate the use of glycerol as an entrainer, in substitution of ethylene glycol in an extractive distillation. The use of glycerol is motivated by the biodiesel production units, due to the fact that it is the main byproduct and a new market is necessary to consume its overproduction. The experiments were carried out in a distillation column packed with Raschig rings, varying the glycerol/feed (ethanol and water ratio, S/F, from 0.5 to 0.9. The samples were analyzed using a digital densimeter. The results showed that glycerol was effective to promote ethanol dehydration and the presence of an azeotrope was not observed using a solvent to feed ratio (S/F equal to 0.9. Some empirical correlations were investigated to evaluate the HETP (Height Equivalent to a Theoretical Plate, and the results provided a useful tool for designing a packed bed column for ethanol-water separation.

Effect of gravity on colloid transport through water-saturated columns packed with glass beads: modeling and experiments.

Science.gov (United States)

Chrysikopoulos, Constantinos V; Syngouna, Vasiliki I

2014-06-17

The role of gravitational force on colloid transport in water-saturated columns packed with glass beads was investigated. Transport experiments were performed with colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b). The packed columns were placed in various orientations (horizontal, vertical, and diagonal) and a steady flow rate of Q = 1.5 mL/min was applied in both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one-dimensional, colloid transport model. The effect of gravity is incorporated in the mathematical model by combining the interstitial velocity (advection) with the settling velocity (gravity effect). The results revealed that flow direction influences colloid transport in porous media. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for colloid deposition.

Prevention and suppression of metal packing fires.

Science.gov (United States)

Roberts, Mark; Rogers, William J; Sam Mannan, M; Ostrowski, Scott W

2003-11-14

Structured packing has been widely used because of large surface area that makes possible columns with high capacity and efficiency. The large surface area also contributes to fire hazards because of hydrocarbon deposits that can easily combust and promote combustion of the thin metal packing materials. Materials of high surface area that can fuel fires include reactive metals, such as titanium, and materials that are not considered combustible, such as stainless steel. Column design and material selection for packing construction is discussed together with employee training and practices for safe column maintenance and operations. Presented also are methods and agents for suppression of metal fires. Guidance for prevention and suppression of metal fires is related to incidents involving packing fires in columns.

Treatment of ammonia in waste air using packed column coupling with chemical reaction

Directory of Open Access Journals (Sweden)

Thepchai, R.

2007-05-01

Full Text Available Ammonia is a common chemical used in various industries. Emission of air contaminated with ammonia to the atmosphere without any treatment causes several effects on human health and environment.A high efficiency method for ammonia removal from waste air is then necessary. In this research, an absorption coupling with chemical reaction was investigated for ammonia removal from waste air using a packedcolumn. The packed column of 10 cm diameter and 200 cm height was packed with 1.4x1.4 cm Raschig rings. Three liquids including water, NaOCl and H2SO4 solution were used as an absorbent for the investigation.The objectives of this research were to determine a suitable absorbent and the optimum condition for ammonia removal from waste air. The packed column was operated at room temperature and atmosphericpressure. The tested conditions were as follows: the gas to liquid ratio (G:L ratio was 35-90 m3 gas/m3 liquid, the inlet concentration of ammonia was 150-500 ppm and the air flow rate was 18 m3/h. The results showedthat the ammonia removal efficiency depends on type of the absorbent and the operating condition. The efficiencies increased with decreasing of G:L ratio and with increasing absorbent concentration. They were70%, 80-92%, and 95-100% for pure water, sodium hypochlorite solution and sulphuric acid solution, respectively. The efficiency decreased with time when water was used as an absorbent while it was almostconstant when NaOCl and H2SO4 solution were applied. The ammonia removal efficiency when using H2SO4 as the absorbent was not dependent on G:L ratio and inlet ammonia concentration, in the range used in thisinvestigation. Since H2SO4 solution gave the highest removal efficiency and can reduce ammonia concentration in waste air to levels which meet the TLV-TWA standard, it is recommended as an absorbent solution forammonia removal from waste air.

Recovery of Filtered Graphene Oxide Residue Using Elastic Gel Packed in a Column by Cross Flow

Directory of Open Access Journals (Sweden)

Yuji Takaoka

2018-04-01

Full Text Available To recover the filtered residues on a gel layer in a column, the method using the elasticity of the gel layer and flowing water in a cross-flow manner is proposed. Polymerized spherical gel (40 μm was packed in a column to a set height of 0.7 cm. The suspensions of graphene oxide at various sizes and shapes were injected on the top of the gel layer and then water was flowed at a flow rate of 1000 mL·h−1 until 0.10 MPa. By releasing the applied pressure, the elastic gel layer rose up, and the filtered graphene oxide also rose above the layer. This rise of the gel layer is due to the difference of pressure between the gel layer, including the filtered graphene oxide, and the open bottom of the column, using the flow of water. The cross flow of water through the column carried away the larger-sized filtered graphene oxide floating above the gel layer. The elasticity of the gel layer and cross flow through the column has the potential to recover the filtered particles.

Retardation characteristics of radionuclides in geologic media through batch and packed column experiments

International Nuclear Information System (INIS)

Park, Hun Hwee; Han, Kyung Won; Han, Pil Soo; Lee, Jae Owan; Park, Chung Kyun; Yang, Ho Yeon

1988-03-01

Batch and packed column experiments are performed to investigate the retardation characteristics of radionuclide,i.e, Cs-137 in geologic media. In batch experiment, the effects of important parameters on the sorption of radionuclide in geologic media, such as nuclide concentration, pH, and particle size are examined. The Kd value obtained from breakthrough curve was compared with that from the batch sorption experiment to investigate the applicability of the Kd value from batch experiment to prediction of radionuclide migration in dynamic flow through porous media. The proposed model of radionuclide migration in porous media is also verified using the experimental results. (Author)

Simple determination of betaine, l-carnitine and choline in human urine using self-packed column and column-switching ion chromatography with nonsuppressed conductivity detection.

Science.gov (United States)

Wei, Dan; Zhu, Yan; Guo, Ming

2018-02-01

A sequential online extraction, clean-up and separation system for the determination of betaine, l-carnitine and choline in human urine using column-switching ion chromatography with nonsuppressed conductivity detection was developed in this work. A self-packed pretreatment column (50 × 4.6 mm, i.d.) was used for the extraction and clean-up of betaine, l-carnitine and choline. The separation was achieved using self-packed cationic exchange column (150 × 4.6 mm, i.d.), followed by nonsuppressed conductivity detection. Under optimized experimental conditions, the developed method presented good analytical performance, with excellent linearity in the range of 0.60-100 μg mL -1 for betaine, 0.75-100 μg mL -1 for l-carnitine and 0.50-100 μg mL -1 for choline, with all correlation coefficients (R 2 ) >0.99 in urine. The limits of detection were 0.15 μg mL -1 for betaine, 0.20 μg mL -1 for l-carnitine and 0.09 μg mL -1 for choline. The intra- and inter-day accuracy and precision for all quality controls were within ±10.32 and ±9.05%, respectively. Satisfactory recovery was observed between 92.8 and 102.0%. The validated method was successfully applied to the detection of urinary samples from 10 healthy people. The values detected in human urine using the proposed method showed good agreement with the measurement reported previously. Copyright © 2017 John Wiley & Sons, Ltd.

Separative analyses of a chromatographic column packed with a core-shell adsorbent for lithium isotope separation

International Nuclear Information System (INIS)

Sugiyama, T.; Sugura, K.; Enokida, Y.; Yamamoto, I.

2015-01-01

Lithium-6 is used as a blanket material for sufficient tritium production in DT fueled fusion reactors. A core-shell type adsorbent was proposed for lithium isotope separation by chromatography. The mass transfer model in a chromatographic column consisted of 4 steps, such as convection and dispersion in the column, transfer through liquid films, intra-particle diffusion and and adsorption or desorption at the local adsorption sites. A model was developed and concentration profiles and time variation in the column were numerically simulated. It became clear that core-shell type adsorbents with thin porous shell were saturated rapidly relatively to fully porous one and established a sharp edge of adsorption band. This is very important feature because lithium isotope separation requires long-distance development of adsorption band. The values of HETP (Height Equivalent of a Theoretical Plate) for core-shell adsorbent packed column were estimated by statistical moments of the step response curve. The value of HETP decreased with the thickness of the porous shell. A core-shell type adsorbent is, then, useful for lithium isotope separation. (authors)

Application of a two-dimensional model for predicting the pressure-flow and compression properties during column packing scale-up.

Science.gov (United States)

McCue, Justin T; Cecchini, Douglas; Chu, Cathy; Liu, Wei-Han; Spann, Andrew

2007-03-23

A two-dimensional model was formulated to describe the pressure-flow behavior of compressible stationary phases for protein chromatography at different temperatures and column scales. The model was based on the assumption of elastic deformation of the solid phase and steady-state Darcy flow. Using a single fitted value for the empirical modulus parameters, the model was applied to describe the pressure-flow behavior of several adsorbents packed using both fluid flow and mechanical compression. Simulations were in agreement with experimental data and accurately predicted the pressure-flow and compression behavior of three adsorbents over a range of column scales and operating temperatures. Use of the described theoretical model potentially improves the accuracy of the column scale-up process, allowing the use of limited laboratory scale data to predict column performance in large scale applications.

The system uranyl nitrate-dietyl ether-water. Extraction by water in spray and packed columns from uranyl nitrate-either solutions

International Nuclear Information System (INIS)

Perez Luina, A.; Gutierrez Jodra, L.

1960-01-01

This paper is a continuation of the one published in Chemical Engineering Progress. Symposium Series, 50, n. 12, 127 (1954). New runs for spray columns, are given and other concentrations in uranyl nitrate for the packed columns. New correlations for the overall H.T.U. are also given. The individual H.T.U. have been grapycally calculated and show that the film resistances have similar values, being independent of the concentration of the ether phase. (Author) 24 refs

Development of the Mo loading apparatus for adsorbing high level 99Mo to PZC and packing in 99mTc generator column

International Nuclear Information System (INIS)

Hishinuma, Yukio; Ohmori, Hiroyuki; Noguchi, Tuneyuki; Tatenuma, Katsuyoshi; Genka, Tsuguo; Machi, Sueo

2006-01-01

For developing the automatic system to produce the PZC- 99m Tc generator column based on (n, gamma) method, we developed and fabricated the proto-type apparatus for semi hot test to prepare and pack PZC adsorbed 99 Mo produced by (n, gamma) method into the generator column; PZC is Mo adsorbent with practical performance for (n, gamma) 99m Tc generator with high 99 Mo adsorption and high 99m Tc elution. For conducting the constant supply and delivery of 99m Tc generator, it is necessary to establish the technology of (n, gamma) method 99m Tc generator using PZC and to develop the fabrication system for 99 Mo loading to PZC and packing the 99m Tc generator column. By the reason, we are developing the Mo loading apparatus. In order to automatically conduct the process of 99 Mo adsorption to PZC and PZC- 99 Mo packing into the generator column, based on one channel system developed by JAERI-KAKEN at 3 years ago, an advanced automatic loading system functioned with 8 channels was developed as FNCA project proceeded by the core with Kaken Co. and JAIF for realizing a mass production of 99m Tc generators, and moreover the Japanese patent regarding the PZC- 99m Tc generator including the automatic loading system of 99 Mo to PZC and making 99m Tc generator columns has already been applied with joint applicants of BATAN and Kaken Co. Regarding the multi-type Mo loading apparatus mentioned above, we set it up in a hot of BATAN at December 2003 year. In this report, we will introduce mainly about the multi-channel automatic loading system of 99 Mo. (author)

Experimental Study of the Flooding and Appearance of a Bubble Bed on Top of a Countercurrent Packed-Bed Column

Czech Academy of Sciences Publication Activity Database

Jiřičný, Vladimír; Staněk, Vladimír; Svoboda, Petr; Ondráček, Jakub

2001-01-01

Roč. 40, č. 1 (2001), s. 407-412 ISSN 0888-5885 R&D Projects: GA ČR GA203/97/1174 Institutional research plan: CEZ:AV0Z4072921 Keywords : appearance * bubble-bed * packed bed column Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.351, year: 2001

Column-Oriented Database Systems (Tutorial)

NARCIS (Netherlands)

D. Abadi; P.A. Boncz (Peter); S. Harizopoulos

2009-01-01

textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as

Longitudinal dispersion coefficient depending on superficial velocity of hydrogen isotopes flowing in column packed with zeolite pellets at 77.4 K

Energy Technology Data Exchange (ETDEWEB)

Kotoh, K. [Faculty of Engineering, Kyushu University, Nishi-ku, Fukuoka (Japan); Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka (Japan); Kubo, K.; Takashima, S.; Moriyama, S.T. [Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka (Japan); Tanaka, M. [National Institute for Fusion Science, Oroshi-cho, Toki, Gifu (Japan); Sugiyama, T. [Faculty of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya (Japan)

2015-03-15

Authors have been developing a cryogenic pressure swing adsorption system for hydrogen isotope separation. In the problem of its design and operation, it is necessary to predict the concentration profiles developing in packed beds of adsorbent pellets. The profiling is affected by the longitudinal dispersion of gas flowing in packed beds, in addition to the mass transfer resistance in porous media of adsorbent pellets. In this work, an equation is derived for estimating the packed-bed dispersion coefficient of hydrogen isotopes, by analyzing the breakthrough curves of trace D{sub 2} or HD replacing H{sub 2} adsorbed in synthetic zeolite particles packed columns at the liquefied nitrogen temperature 77.4 K. Since specialized for hydrogen isotopes, this equation can be considered to estimate the dispersion coefficients more reliable for the cryogenic hydrogen isotope adsorption process, than the existing equations. (authors)

Biosorption of lead(II) and cadmium(II) by protonated Sargassum glaucescens biomass in a continuous packed bed column

International Nuclear Information System (INIS)

Naddafi, Kazem; Nabizadeh, Ramin; Saeedi, Reza; Mahvi, Amir Hossein; Vaezi, Forough; Yaghmaeian, Kamyar; Ghasri, Azar; Nazmara, Shahrokh

2007-01-01

Biosorption of lead(II) and cadmium(II) from aqueous solutions by protonated Sargassum glaucescens biomass was studied in a continuous packed bed column. The selective uptake of Pb 2+ and Cd 2+ was investigated in a binary system with initial concentration of 1 mM for each metal ion. The selective uptake capacities of Pb 2+ and Cd 2+ at complete exhaustion point were obtained 1.18 and 0.22 mmol/g, respectively; therefore, the biosorbent showed much higher relative affinity for Pb 2+ than for Cd 2+ . The optimum range of empty bed contact time (EBCT) was identified as 5-10 min in the packed bed column. The efficiency of biosorbent regeneration by 0.1 M HCl was achieved about 60%, so that the maximum uptake capacity of Pb 2+ by the regenerated biomass was determined to be 0.75 mmol/g while the same value for the original biomass was 1.24 mmol/g. The Thomas model was found in a suitable fitness with the experimental data (R 2 > 0.90 and ε% + with the uptake of heavy metals; hence, ion exchange was confirmed to be one of the main biosorption mechanisms

Experimental engineering section off-gas decontamination facility's fractionator column: installation and performance

International Nuclear Information System (INIS)

Gilliam, T.M.; Fowler, V.L.; Inman, D.J.

1978-03-01

A detailed description of the third column recently installed in the Experimental Engineering Section Off-Gas Decontamination Facility (EES-ODF) is presented. The EES-ODF is being used to provide engineering-scale experiments (nominal gas and liquid flows of 5 scfm and 0.5 gpm, respectively) in the development of the Krypton Absorption in Liquid CO 2 (KALC) process. A detailed discussion of the column's construction is provided. This discussion includes the peripherals associated with the column, such as refrigeration, heat exchangers, instrumentation, etc. The compressibility of Goodloe packing (the packing in the other columns) and the possible reduced throughput due to this compression have revealed the desirablility of a random (i.e., noncompressible) packing. Toward this end, the third column is packed with a new random packing (PRO-PAK). A preliminary comparison between this packing and the woven wire mesh packing (Goodloe) used in the other two columns has been made. Experiments comparing the throughput capacity indicate that the PRO-PAK packing has approximately 60% the capacity of Goodloe for a CO 2 system. When used as a fractionator or stripper with the basic O 2 -Kr-CO 2 KALC system, the PRO-PAK column produced HTU values less than or equal to the GOODLOE columns under similar operating conditions

Highly efficient high-performance liquid chromatographic separation of xylene isomers and phthalate acid esters on a homemade DUT-67(Zr) packed column.

Science.gov (United States)

Chen, Sha; Li, Xiao-Xin; Feng, Fan; Li, Sumei; Han, Jia-Hui; Jia, Zi-Yi; Shu, Lun; Somsundaran, P; Li, Jian-Rong

2018-04-16

In this study, the baseline separations of xylene isomers and phthalate acid esters on a homemade DUT-67(Zr) packed column were achieved, respectively. The high selectivity for xylene isomers and phthalate acid esters was obtained with the increase of temperature and decrease of the retention time. The hydrophobicity of xylene isomers and phthalate acid esters caused the different separation time on the DUT-67(Zr) packed column. The relative standard deviation values of retention time, peak area, peak height and half peak width for five repeat separation of the xylene isomers were 0.26-0.35, 2.11-2.26, 1.51-2.03, and 0.29-0.77%, and the values of the phthalate acid esters on DUT-67(Zr) column were 0.1-0.4, 4.4-5.2, 3.9-6.3, and 0.6-2.1%, respectively. The thermodynamic properties indicated that the separation of xylene isomers was controlled by ΔH and ΔS, but the separation of phthalate acid esters was mainly controlled by ΔS. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

EXPERIMENTAL STUDY ON HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR OF Al2O3 NANOFLUID IN A PACKED BED COLUMN

Directory of Open Access Journals (Sweden)

G. Srinivasa Rao

2011-12-01

Full Text Available The forced convection heat transfer coefficient and friction factor are determined for the flow of water and nanofluid in a vertical packed bed column. The analysis is undertaken in the laminar and transition Reynolds number range. The column is filled with spherical glass beads as the bed material. The heat transfer coefficients with Al2O3 nanofluid increased by 12% to 15% with the increase of volume concentration from 0.02% to 0.5% compared with water. The experimental values of axial temperature are in good agreement with the NTU-ε method proposed by Schumann’s model.

Separation of rate processes for isotopic exchange between hydrogen and liquid water in packed columns 10

International Nuclear Information System (INIS)

Butler, J.P.; Hartog, J. den; Goodale, J.W.; Rolston, J.H.

1977-01-01

Wetproofed platinum catalysts in packed columns promote isotopic exchange between counter-current streams of hydrogen saturated with water vapour and liquid water. The net rate of deuterium transfer from isotopically enriched hydrogen has been measured and separated into two rate processes involving the transfer of deuterium from hydrogen to water vapour and from water vapour to liquid. These are compared with independent measurements of the two rate processes to test the two-step successive exchange model for trickle bed reactors. The separated transfer rates are independent of bed height and characterize the deuterium concentrations of each stream along the length of the bed. The dependences of the transfer rates upon hydrogen and liquid flow, hydrogen pressure, platinum loading and the effect of dilution of the hydrophobic catalyst with inert hydrophilic packing are reported. The results indicate a third process may be important in the transfer of deuterium between hydrogen and liquid water. (author)

Degradation of nitrobenzene in simulated wastewater by iron-carbon micro-electrolysis packing.

Science.gov (United States)

Li, Meng; Zou, Donglei; Zou, Haochen; Fan, Dongyan

2011-12-01

The reductive degradation of nitrobenzene (NB) by iron-carbon micro-electrolysis packing was investigated. The influence of initial NB concentration, pH value and packing amount on the removal rate of NB were studied. The results showed that the reaction with packing followed the pseudo-first-order reaction. The optimum pH was 3.0 for the degradation of NB in the tested pH ranges of 3-9 and the optimum packing amount was 40 g/200 ml. The flow-through column packed with packing was designed to remove NB from simulated wastewater for approximately 68 days. The removal rate was over 90% within initial periods. It could be seen that after running for 68 days, the packing still had good performance after the long-term column experiment. In addition, the changes of the packing surfaces morphologies and matters before, during and after the column experiment were analysed by scanning electron microscopy in conjunction with energy-dispersion spectroscopy (EDS).

Biosorption of copper by marine algae Gelidium and algal composite material in a packed bed column.

Science.gov (United States)

Vilar, Vítor J P; Botelho, Cidália M S; Loureiro, José M; Boaventura, Rui A R

2008-09-01

Marine algae Gelidium and algal composite material were investigated for the continuous removal of Cu(II) from aqueous solution in a packed bed column. The biosorption behaviour was studied during one sorption-desorption cycle of Cu(II) in the flow through column fed with 50 and 25 mg l(-1) of Cu(II) in aqueous solution, at pH 5.3, leading to a maximum uptake capacity of approximately 13 and 3 mg g(-1), respectively, for algae Gelidium and composite material. The breakthrough time decreases as the inlet copper concentration increases, for the same flow rate. The pH of the effluent decreases over the breakthrough time of copper ions, which indicates that ion exchange is one of the mechanisms involved in the biosorption process. Temperature has little influence on the metal uptake capacity and the increase of the ionic strength reduces the sorption capacity, decreasing the breakthrough time. Desorption using 0.1M HNO(3) solution was 100% effective. After two consecutive sorption-desorption cycles no changes in the uptake capacity of the composite material were observed. A mass transfer model including film and intraparticle resistances, and the equilibrium relationship, for adsorption and desorption, was successfully applied for the simulation of the biosorption column performance.

Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

International Nuclear Information System (INIS)

Seungwoo Paek; Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

2006-01-01

Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

Column-Oriented Database Systems (Tutorial)

OpenAIRE

Abadi, D.; Boncz, Peter; Harizopoulos, S.

2009-01-01

textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as opposed to traditional database systems that store entire records (rows) one after the other. Reading a subset of a table’s columns becomes faster, at the potential expense of excessive disk-head s...

Post column derivatisation analyses review. Is post-column derivatisation incompatible with modern HPLC columns?

Science.gov (United States)

Jones, Andrew; Pravadali-Cekic, Sercan; Dennis, Gary R; Shalliker, R Andrew

2015-08-19

Post Column derivatisation (PCD) coupled with high performance liquid chromatography or ultra-high performance liquid chromatography is a powerful tool in the modern analytical laboratory, or at least it should be. One drawback with PCD techniques is the extra post-column dead volume due to reaction coils used to enable adequate reaction time and the mixing of reagents which causes peak broadening, hence a loss of separation power. This loss of efficiency is counter-productive to modern HPLC technologies, -such as UHPLC. We reviewed 87 PCD methods published from 2009 to 2014. We restricted our review to methods published between 2009 and 2014, because we were interested in the uptake of PCD methods in UHPLC environments. Our review focused on a range of system parameters including: column dimensions, stationary phase and particle size, as well as the geometry of the reaction loop. The most commonly used column in the methods investigated was not in fact a modern UHPLC version with sub-2-micron, (or even sub-3-micron) particles, but rather, work-house columns, such as, 250 × 4.6 mm i.d. columns packed with 5 μm C18 particles. Reaction loops were varied, even within the same type of analysis, but the majority of methods employed loop systems with volumes greater than 500 μL. A second part of this review illustrated briefly the effect of dead volume on column performance. The experiment evaluated the change in resolution and separation efficiency of some weak to moderately retained solutes on a 250 × 4.6 mm i.d. column packed with 5 μm particles. The data showed that reaction loops beyond 100 μL resulted in a very serious loss of performance. Our study concluded that practitioners of PCD methods largely avoid the use of UHPLC-type column formats, so yes, very much, PCD is incompatible with the modern HPLC column. Copyright © 2015. Published by Elsevier B.V.

Removal of H₂S from Biogas by Iron (Fe³⁺ Doped MgO on Ceramic Honeycomb Catalyst using Double Packed Columns System

Directory of Open Access Journals (Sweden)

Juntima Chungsiriporn

2010-03-01

Full Text Available Hydrogen sulfide is a toxic and corrosive in nature, gas should be safely removed from the biogas streams before subjecting into the fuel cell. Fe3+ doped magnesium oxide was synthesized using sol-gel technique and dip coating process of Fe3+ doped MgO on foam ceramic honeycomb. XRD and SEM indicate that Fe3+ in Fe3+ doped MgO on foam ceramic honeycomb catalyst is finely dispersed in the MgO support. Performance of the synthesized Fe3+ doped magnesium oxide on the honeycomb catalyst was examined for hydrogen sulfide (H2S oxidation by double packed column scrubbers. The absorption column was used for H2S scrubbing from biogas by deionized water absorption and catalytic column was used as catalyst bed for degradation of absorbed H2S in scrubbing water. In the catalytic column, counter current flow of the scrubbing water and air through the catalyst pack was performed for H2S oxidation accompany with catalyst regeneration. System capacity for H2S removal from gas stream showed 98% constant along 3 hr testing time at room temperature.

Continuous cadmium removal from aqueous solutions by seaweed in a packed-bed column under consecutive sorption-desorption cycles

International Nuclear Information System (INIS)

Jafari, Seyed Ali; Jamali, Abbas

2016-01-01

Packed-bed column process efficiency for cadmium adsorption from aqueous solution was investigated under different bed heights (2.6 to 7.5 cm) and feed flow rates (15 to 30 ml min -1 ). The column was filled with brown seaweed, Sargassum angustifolium. Three simplified models, including Bed Depth Service Time, Thomas, and Yoon- Nelson were employed for describing the experimental breakthrough curves as well as achieving design parameters. Bed lifetime was also evaluated in several consecutive sorption-desorption cycles. Cadmium concentration of 0.005mg l−1, as a standard limit for potable water, was considered as the breakthrough concentration. The maximum column performance was achieved 81% at 7.5 cm bed length and flow rate of 15 ml min -1 . Indeed, increasing the bed height increased the sorption performance and service time, while increasing the feed flow rate had a negative effect. Maximum sorption capacity value remained almost constant by the bed height changes; however, increase in the feed flow rate slightly decreased it. The modeling results revealed that the Yoon-Nelson model was more accurate than Thomas for describing the experimental breakthrough data, especially at low flow rates. Column service time predictions were surprisingly achieved using the Bed Depth Service Time model even at extrapolations. 20% reduction in column adsorption efficiency was observed at the end of four consecutive sorption-desorption cycles; however, desorption efficiencies were achieved more than 99% in each cycle.

Continuous cadmium removal from aqueous solutions by seaweed in a packed-bed column under consecutive sorption-desorption cycles

Energy Technology Data Exchange (ETDEWEB)

Jafari, Seyed Ali; Jamali, Abbas [Persian Gulf Research Institute, Persian Gulf University, 75169, Bushehr (Iran, Islamic Republic of)

2016-04-15

Packed-bed column process efficiency for cadmium adsorption from aqueous solution was investigated under different bed heights (2.6 to 7.5 cm) and feed flow rates (15 to 30 ml min{sup -1}). The column was filled with brown seaweed, Sargassum angustifolium. Three simplified models, including Bed Depth Service Time, Thomas, and Yoon- Nelson were employed for describing the experimental breakthrough curves as well as achieving design parameters. Bed lifetime was also evaluated in several consecutive sorption-desorption cycles. Cadmium concentration of 0.005mg l−1, as a standard limit for potable water, was considered as the breakthrough concentration. The maximum column performance was achieved 81% at 7.5 cm bed length and flow rate of 15 ml min{sup -1}. Indeed, increasing the bed height increased the sorption performance and service time, while increasing the feed flow rate had a negative effect. Maximum sorption capacity value remained almost constant by the bed height changes; however, increase in the feed flow rate slightly decreased it. The modeling results revealed that the Yoon-Nelson model was more accurate than Thomas for describing the experimental breakthrough data, especially at low flow rates. Column service time predictions were surprisingly achieved using the Bed Depth Service Time model even at extrapolations. 20% reduction in column adsorption efficiency was observed at the end of four consecutive sorption-desorption cycles; however, desorption efficiencies were achieved more than 99% in each cycle.

Enantioselective Analytical- and Preparative-Scale Separation of Hexabromocyclododecane Stereoisomers Using Packed Column Supercritical Fluid Chromatography.

Science.gov (United States)

Riddell, Nicole; Mullin, Lauren Gayle; van Bavel, Bert; Ericson Jogsten, Ingrid; McAlees, Alan; Brazeau, Allison; Synnott, Scott; Lough, Alan; McCrindle, Robert; Chittim, Brock

2016-11-10

Hexabromocyclododecane (HBCDD) is an additive brominated flame retardant which has been listed in Annex A of the Stockholm Convention for elimination of production and use. It has been reported to persist in the environment and has the potential for enantiomer-specific degradation, accumulation, or both, making enantioselective analyses increasingly important. The six main stereoisomers of technical HBCDD (i.e., the (+) and (-) enantiomers of α-, β-, and γ-HBCDD) were separated and isolated for the first time using enantioselective packed column supercritical fluid chromatography (pSFC) separation methods on a preparative scale. Characterization was completed using published chiral liquid chromatography (LC) methods and elution profiles, as well as X-ray crystallography, and the isolated fractions were definitively identified. Additionally, the resolution of the enantiomers, along with two minor components of the technical product (δ- and ε-HBCDD), was investigated on an analytical scale using both LC and pSFC separation techniques, and changes in elution order were highlighted. Baseline separation of all HBCDD enantiomers was achieved by pSFC on an analytical scale using a cellulose-based column. The described method emphasizes the potential associated with pSFC as a green method of isolating and analyzing environmental contaminants of concern.

Use of a Packed-Column Bioreactor for Isolation of Diverse Protease-Producing Bacteria from Antarctic Soil

Science.gov (United States)

Wery, Nathalie; Gerike, Ursula; Sharman, Ajay; Chaudhuri, Julian B.; Hough, David W.; Danson, Michael J.

2003-01-01

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10°C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were mainly psychrotrophs and presented a high morphological and metabolical diversity. The extracellular protease activities tested were optimal at neutral pH and between 30 and 45°C. 16S ribosomal DNA sequence analyses showed that the bioreactor was colonized by a wide variety of taxons, belonging to various bacterial divisions: α-, β-, and γ-Proteobacteria; the Flexibacter-Cytophaga-Bacteroides group; and high G+C gram-positive bacteria and low G+C gram-positive bacteria. Some strains represent candidates for new species of the genera Chryseobacterium and Massilia. This diversity demonstrates that the bioreactor is an efficient enrichment tool compared to traditional isolation strategies. PMID:12620829

Evaluation of monolithic and sub 2 microm particle packed columns for the rapid screening for illicit drugs--application to the determination of drug contamination on Irish euro banknotes.

Science.gov (United States)

Bones, Jonathan; Macka, Mirek; Paull, Brett

2007-03-01

A study comparing recently available 100 x 3 mm id, 200 x 3 mm id monolithic reversed-phase columns with a 50 x 2.1 mm id, 1.8 microm particle packed reversed-phase columns was carried out to determine the most efficient approach (using traditional van Deemter analysis and a modern kinetic plot approach) for the rapid screening of samples for 16 illicit drugs and associated metabolites. A plot of column backpressure versus plate number (N) showed a significant advantage of using the monolithic phases, with the 20 cm monolithic column exhibiting a maximum 15,000 plates at a column backpressure of approximately 70 bar, compared to approximately 7000 plates at 150 bar for the 5 cm 1.8 microm particle packed column. Optimum linear velocities were found to be 0.40 mm s(-1), 0.52 mm s(-1) and 0.98 mm s(-1) for the three above columns, respectively. The 20 cm monolithic column was subsequently applied to the separation and determination of illicit drug contamination on Irish euro banknotes, using methanol extraction followed by LC-MS/MS. Method performance data showed that the new LC-MS/MS method was significantly more sensitive than previous GC-MS/MS based methods for this application, with detection limits in the pg note(-1) region, based upon a 20 microL standard injection. All of the notes examined tested positive for trace quantities of cocaine, with benzoylecgonine detected on 12 of the 45 notes sampled. Traces of heroin were also detected on three of the 45 notes.

Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

Energy Technology Data Exchange (ETDEWEB)

Seungwoo Paek [KAERI (Korea, Republic of); Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

2006-07-01

Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

Gamma ray scanning as troubleshooting tool for unusual and large diameter refinery vacuum columns

International Nuclear Information System (INIS)

Sarkar, T.K.; Chawla, R.; Banik, S.; Chopra, S.J.; Singh, G.; Pant, H.J.; Sreeramakrishnan, P.; Dhar, D.C.; Pushpangathan, P.N.; Sharma, V.K.

1997-01-01

Gamma scanning of trayed and packed columns is widely used to obtain density profiles and identify on-line problems such as: damaged tray or packing, foaming, flooding, maldistribution, weeping and entrainment, etc. However, scanning of large diameter tray or packed columns requires expertise in handling high intensity gamma sources along with thorough understanding of distillation engineering. Engineers India Limited and the Bhabha Atomic Research Centre undertook scanning of two such large diameter (8.4 m and 7.4 m) trayed and packed refinery vacuum distillation columns and successfully diagnosed the problems and suggested remedial actions. Radiography testing of small diameter columns can be used to confirm gamma scanning results. One such example for ammonia separator column is given

Practical issues relating to soil column chromatography for sorption parameter determination.

Science.gov (United States)

Bi, Erping; Schmidt, Torsten C; Haderlein, Stefan B

2010-08-01

Determination of sorption distribution coefficients (K(d)) of organic compounds by a dynamic soil column chromatography (SCC) method was developed and validated. Eurosoil 4, quartz, and alumina were chosen as exemplary packing materials. Heterocyclic aromatic compounds were selected in the validation of SCC. The prerequisites of SCC with regard to column dimension, packing procedure, and sample injection volume are discussed. Reproducible soil column packing was achieved by addition of a pre-column and an HPLC pump for subsequent compression of the packed material. Various methods to determine retention times from breakthrough curves are discussed and the use of the half mass method is recommended. To dilute soil with inert material can prevent column-clogging and help to complete experiments in a reasonable period of time. For the chosen probe compounds, quartz rather than alumina proved a suitable dilution material. Non-equilibrium issue can be overcome by conducting the experiments under different flowrates and/or performing numerical simulation. Copyright 2010 Elsevier Ltd. All rights reserved.

Radial heterogeneity of some analytical columns used in high-performance liquid chromatography.

Science.gov (United States)

Abia, Jude A; Mriziq, Khaled S; Guiochon, Georges A

2009-04-10

An on-column electrochemical microdetector was used to determine accurately the radial distribution of the mobile phase velocity and of the column efficiency at the exit of three common analytical columns, namely a 100 mm x 4.6mm C18 bonded silica-based monolithic column, a 150 mm x 4.6mm column packed with 2.7 microm porous shell particles of C18 bonded silica (HALO), and a 150 mm x 4.6mm column packed with 3 microm fully porous C18 bonded silica particles (LUNA). The results obtained demonstrate that all three columns are not radially homogeneous. In all three cases, the efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius). The decrease in local efficiency from the core to the wall regions was lower in the case of the monolith (ca. 25%) than in that of the two particle-packed columns (ca. 35-50%). The mobile phase velocity was found to be ca. 1.5% higher in the wall than in the core region of the monolithic column while, in contrast, it was ca. 2.5-4.0% lower in the wall region for the two particle-packed columns.

CFD simulation of alleviation of fluid back mixing by baffles in bubble column

Energy Technology Data Exchange (ETDEWEB)

Xia, Y.K.; Peng, F.F.; Wolfe, E. [Sedgman LLC, Pittsburgh, PA (United States)

2006-07-15

The global back mixing of liquid in an open flotation column is harmful to mineral separations. The inclusion of baffles and packing in open columns can dampen the effects of global back mixing. A mathematical model based on the principle of fluid dynamics is helpful in designing baffled or packed columns. This paper presents a two-dimensional Euler-Lagrangian model to simulate the multiphase flow for some cases of baffled and packed columns. Fluid motion is calculated by directly solving the Navier-Stokes equations by a SIMPLE approach. Bubbles are moved in a Lagrangian frame through the interaction forces imposed by the gas-fluid coupling. The simulated results successfully reveal that the liquid back-mixing effect in the open bubble columns can be alleviated by baffles or packings.

Breakthrough characteristics of gas absorption in a packed column

International Nuclear Information System (INIS)

Shitanda, Shoji; Fukada, Satoshi; Koto, Kenji; Mitsuishi, Nobuo

1979-01-01

In nuclear industries, the operations to collect or recover various radioactive and non-radioactive gases with a number of absorption or adsorption reagents are practically utilized or planned. Specifically in the operations of recovering hydrogen isotopes, the direct collecting method with active metals such as uranium, zirconium (Zr) and yttrium is watched with keen interest. In this study, the capability of recovering hydrogen by means of Zr was investigated through the estimation of rate-determining step, by flowing the gas mixture of hydrogen and argon after activating metallic Zr under the condition of high temperature and high vacuum, and by determining overall mass transfer coefficient from the absorption breakthrough curves. The details of a packed column and the flowsheet are also described, and the deterioration of Zr powder is considered. That is, the diffusion speed and absorbing reaction speed of hydrogen in Zr particles are supposed to be slow and dominant in mass transfer speed. Further, since gas mixture does not simply diffuse in Zr particles, but the reaction plane seems to move toward the center from the surface in the case of Zr, different from general adsorbents, the moving speed seems to give large effect on the rate-determining step. It is ensured that the hydrogen absorption with Zr powder is so active that hydrogen in gas flow can easily be recovered, and its separation from other gases can be effectively carried out by the desorption of hydrogen from Zr powder by heating it in vacuum. (Wakatsuki, Y.)

Effects of the gas-liquid ratio on the optimal quantity of the catalyst for the CECE process with a homogeneously packed LPCE column

International Nuclear Information System (INIS)

Ushida, A.; Sugiyama, T.; Yamamoto, I.

2007-01-01

In order to improve the separative performance of a CECE (Combined Electrolysis Catalytic Exchange) process we have been carried out experimental studies on hydrogen isotope separation by a CECE process using with a LPCE (Liquid Phase Catalytic Exchange) column of trickle-type bed. Two types of trickle beds were tested in our previous study. One was the layered bed where layers of Kogel catalysts and that of Dixon gauze rings were filled in the column alternately. The other was the homogeneous bed where Kogel catalysts and Dixon gauze rings were mixed and filled in the column homogeneously. We found two major points: 1) the homogeneous bed was more efficient than the layered bed and 2) there was an optimal quantity of the catalyst for both types of beds to obtain the largest separation factor. The optimal quantity of the catalyst is affected by various factors such as catalytic activity, flow rates of fluid, temperature and so on. In this study we focused on an effect of the gasliquid ratio. The purpose of the present study is to investigate experimentally the effect of the gas-liquid ratio on the optimal quantity of the catalyst using with a homogeneous bed. The column is a Pyrex glass tube with 25 mm internal diameter and 60 cm length. The column is filled with Kogel catalysts (1.0 wt% Pt deposited) and Dixon gauze rings. A catalyst packed-ratio is defined as a ratio of the grain-volume of catalyst to the grain volume of the whole packings, where grain volumes mean the volume of a sphere with average diameter of the Kogel catalyst and the volume of a cylinder which has the outer shape same as a Dixon gauze ring. Hydrogen-deuterium isotope separation with the CECE equipment was performed at 101 kPa, 343 K for various values of the catalyst packed-ratio and for various values of the gas-liquid ratio. Hydrogen gas was generated by the Solid Polymer Electrolysis (SPE) electrolyzer. Maximum production rate and purity of hydrogen gas are 1 m3/h and 99.99%. The

Enantioselective Analytical- and Preparative-Scale Separation of Hexabromocyclododecane Stereoisomers Using Packed Column Supercritical Fluid Chromatography

Directory of Open Access Journals (Sweden)

Nicole Riddell

2016-11-01

Full Text Available Hexabromocyclododecane (HBCDD is an additive brominated flame retardant which has been listed in Annex A of the Stockholm Convention for elimination of production and use. It has been reported to persist in the environment and has the potential for enantiomer-specific degradation, accumulation, or both, making enantioselective analyses increasingly important. The six main stereoisomers of technical HBCDD (i.e., the (+ and (− enantiomers of α-, β-, and γ-HBCDD were separated and isolated for the first time using enantioselective packed column supercritical fluid chromatography (pSFC separation methods on a preparative scale. Characterization was completed using published chiral liquid chromatography (LC methods and elution profiles, as well as X-ray crystallography, and the isolated fractions were definitively identified. Additionally, the resolution of the enantiomers, along with two minor components of the technical product (δ- and ε-HBCDD, was investigated on an analytical scale using both LC and pSFC separation techniques, and changes in elution order were highlighted. Baseline separation of all HBCDD enantiomers was achieved by pSFC on an analytical scale using a cellulose-based column. The described method emphasizes the potential associated with pSFC as a green method of isolating and analyzing environmental contaminants of concern.

Comparison of Granular Activated Carbon, Natural Clinoptilolite Zeolite, and Anthracite Packed Columns in Removing Mercury from Drinking Water

Directory of Open Access Journals (Sweden)

Mohammad Taghi Samadi

2010-01-01

Full Text Available Development of effective methods for the removal of such pollutants as heavy metals (e.g., mercury from surface and ground water resources introduced by municipal and industrial wastewaters seems to be inevitable, especially in the face of the importance of water reuse in combating water shortages, limited availability of water resources, and imminent risks of a water crisis in Iran. A number of methods are already available for the removal of mercury from water resources. However, these techniques must be investigated for their practicability and economy, in addition to their not only effectiveness. In this research, granular activated carbon, natural zeolite, and anthracite packed-columns were investigated as cheap and effective adsorbents for the removal of mercury. Moreover, the effects of changes in pH (6-8, influent mercury concentrations (0.25, 0.5, 0.75, and 1 ppm, contact time (0.5, 1, 2, 3 hr were investigated. Mercury concentration in the samples was determined using a ditizon indicator and spectrophotometry at 492 nm. Results showed that decreasing influent mercury concentration from 1 ppm to 0.25 ppm (under constant conditions increased the removal efficiencies of anthracite, granular activated carbon, and zeolite columns from22%, 63%, and 55% to 28%, 72%, and 64%, respectively. Increasing contact time from 0.5 hr to 3 hr caused the removal efficiencies of these columns to increase from 22%, 56%, and 54% to 42%, 86%, and 82%, respectively. Also, increasing pH level led to increased removal efficiencies of the studied columns. It was found that contact time played a more effective role in enhancing mercury removal efficiency in the granular activated carbon column than in the other two columns. The ranges of mercury removal efficiency obtained for the granular activated carbon, natural zeolite, and anthracite columns under various conditions were (51%-92%, (42%-88%, and (16%-52%, respectively. Based on these results, granular

Boron isotope fractionation in column chromatography with glucamine type fibers

International Nuclear Information System (INIS)

Sonoda, Akinari; Makita, Yoji; Hirotsu, Takahiro

2008-01-01

Glucamine type polymers have specific affinity toward boric acid and borate ion. Among them, Chelest Fiber GRY-L showed larger fractionation for boron isotopes than other polymers in our previous study. For this study, we used Chelest Fibers with different fiber lengths (1.0 mm, 0.5 mm, and 0.3 mm) as column packing materials to perform chromatographic separation of boron isotopes. The shorter fiber has larger packing density when packed into the column using a dry method. The 0.3-mm-long fiber has a larger backpressure than fibers of other lengths. Boron adsorption capacities were measured using the breakthrough operation. At this time, the 0.5-mm-long fiber showed the highest capacity. When we measured the isotope ratio profile for fibers of different length using column chromatography, 0.5-mm-long fibers displayed the highest boron isotope fractionation. The 0.5-mm-long fiber is promising as a packing material of column chromatography for boron isotope separation. We also changed operation methods. The lower eluent concentration and the slower flow rate are suitable for boron isotope separation. (author)

Influence of pressure on the properties of chromatographic columns. II. The column hold-up volume.

Science.gov (United States)

Gritti, Fabrice; Martin, Michel; Guiochon, Georges

2005-04-08

The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C18-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C18 (10% carbon) and the Symmetry-C18 (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C18-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.

Removal of the brilliant blue through packed columns using corncobs

Directory of Open Access Journals (Sweden)

Angelina Hormaza Anaguano

2014-05-01

Full Text Available This research shows the adsorbent potential of corncobs in the removal of the anionic bright blue colorant on packed beds. It was evaluated the effect of pH parameters from this medium, particle size, saline presence and column height. The samples were analyzed by defined intervals of time. The colorant quantity removed was quantified by means of ultraviolet-visible spectroscopy. Models of Adams-Bohart, Thomas and Yoon-Nelson were used to predict the breakthrough curves using nonlinear regression and so set the characteristic parameters of the process. BDST model was used to express the influence of bed height into the breakthrough curve. It was found that acid pH (pH = 2.0 smaller particle size (0.3 mm < x < 0.5 mm and larger bed height (Z = 20 cm favor the transfer of colorant to the adsorbent material, reaching greater retention of bright blue on the corncob. The presence of NaCl in the solution reduces the efficiency of adsorption. In terms of models, the Thomas model presented the best setting for the description of the breakthrough curve to the experimental conditions (R2 = 0.93 -0.94, while Adams-Bohart model offered a good fit (R2 = 0.96-0.99 for the dynamic behavior limited  to the initial part of the process. Yoon-Nelson model presented a considerable drift between the experimental data and the predicted data. Finally, the BDST model showed a good correlation, R2 = 0.92 -0.99, establishing that the height is a determining factor for scaling of process

Cotransport of clay colloids and viruses through water-saturated vertically oriented columns packed with glass beads: Gravity effects.

Science.gov (United States)

Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

2016-03-01

The cotransport of clay colloids and viruses in vertically oriented laboratory columns packed with glass beads was investigated. Bacteriophages MS2 and ΦX174 were used as model viruses, and kaolinite (ΚGa-1b) and montmorillonite (STx-1b) as model clay colloids. A steady flow rate of Q=1.5 mL/min was applied in both vertical up (VU) and vertical down (VD) flow directions. In the presence of KGa-1b, estimated mass recovery values for both viruses were higher for VD than VU flow direction, while in the presence of STx-1b the opposite was observed. However, for all cases examined, the produced mass of viruses attached onto suspended clay particles were higher for VD than VU flow direction, suggesting that the flow direction significantly influences virus attachment onto clays, as well as packed column retention of viruses attached onto suspended clays. KGa-1b hindered the transport of ΦX174 under VD flow, while STx-1b facilitated the transport of ΦX174 under both VU and VD flow directions. Moreover, KGa-1b and STx-1b facilitated the transport of MS2 in most of the cases examined except of the case where KGa-1b was present under VD flow. Also, the experimental data were used for the estimation of virus surface-coverages and virus surface concentrations generated by virus diffusion-limited attachment, as well as virus attachment due to sedimentation. Both sedimentation and diffusion limited virus attachment were higher for VD than VU flow, except the case of MS2 and STx-1b cotransport. The diffusion-limited attachment was higher for MS2 than ΦΧ174 for all cases examined. Copyright © 2015 Elsevier B.V. All rights reserved.

Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns

International Nuclear Information System (INIS)

Ersoez, Arzu; Say, Ridvan; Denizli, Adil

2004-01-01

Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid-liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have developed a polymer obtained by imprinting with Ni(II) ion as a ion-imprinted SPE sorbent. For this purpose, NI(II)-methacryloylhistidinedihydrate (MAH/Ni(II)) complex monomer was synthesized and polymerized with cross-linking ethyleneglycoldimethacrylate to obtain [poly(EGDMA-MAH/Ni(II))]. Then, Ni(II) ions were removed from the polymer getting Ni(II) ion-imprinted sorbent. The MIP-SPE preconcentration procedure showed a linear calibration curve within concentration range from 0.3 to 25 ng/ml and the detection limit was 0.3 ng/ml (3 s) for flame atomic absorption spectrometry (FAAS). Ni(II) ion-imprinted microbeads can be used several times without considerable loss of adsorption capacity. When the adsorption capacity of nickel imprinted microbeads were compared with non-imprinted microbeads, nickel imprinted microbeads have higher adsorption capacity. The K d (distribution coefficient) values for the Ni(II)-imprinted microbeads show increase in K d for Ni(II) with respect to both K d values of Zn(II), Cu(II) and Co(II) ions and non-imprinted polymer. During that time K d decreases for Zn(II), Cu(II) and Co(II) ions and the k' (relative selectivity coefficient) values which are greater than 1 for imprinted microbeads of Ni(II)/Cu(II), Ni(II)/Zn(II) and Ni(II)/Co(II) are 57.3, 53.9, and 17.3, respectively. Determination of Ni(II) ion in sea water showed that the interfering matrix had been almost removed during preconcentration. The column was good enough for Ni determination in matrixes containing similar ionic radii ions such as Cu(II), Zn(II) and Co(II)

Simultaneous removal of SO2 and NOX with ammonia absorbent in a packed column

International Nuclear Information System (INIS)

Jia, Yong; Du, Daqian; Zhang, Xinxi; Ding, Xilou; Zhong, Oin

2013-01-01

Catalytic oxidation of NO followed by simultaneous removal of SO 2 and NO X with ammonia is a promising method for control of coal-fired flue gas pollutants. We investigated simultaneous absorption of SO 2 and NO X in a packed column with ammonia, and found that SO 2 and NO X could promote absorption with each other in the process of simultaneous removal SO 2 and NO X . The removal efficiency of SO 2 and NO X was, respectively, about 98% and 70.9% at pH 5.5, temperature 323.15 K, SO 2 concentration 1,800x10 −6 , NO X concentration 400x10 −6 and m NO2 /m NO 1 in our experimental system. The experimental results also show that the formation of sulfite oxidized by reacting with dissolved NO 2 and the molar ratio of sulfite to total sulfur is more than 0.8 in the solution. Accordingly, the energy consumption for sulfite oxidation would be greatly reduced in the process of simultaneous desulfurization and denitrification with ammonia

Mass transfer model liquid phase catalytic exchange column simulation applicable to any column composition profile

Energy Technology Data Exchange (ETDEWEB)

Busigin, A. [NITEK USA Inc., Ocala, FL (United States)

2015-03-15

Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.

Single column and two-column H-D-T distillation experiments at TSTA

International Nuclear Information System (INIS)

Yamanishi, T.; Yoshida, H.; Hirata, S.; Naito, T.; Naruse, Y.; Sherman, R.H.; Bartlit, J.R.; Anderson, J.L.

1988-01-01

Cryogenic distillation experiments were peformed at TSTA with H-D-T system by using a single column and a two-column cascade. In the single column experiment, fundamental engineering data such as the liquid holdup and the HETP were measured under a variety of operational condtions. The liquid holdup in the packed section was about 10 /approximately/ 15% of its superficial volume. The HETP values were from 4 to 6 cm, and increased slightly with the vapor velocity. The reflux ratio had no effect on the HETP. For the wo-colunn experiemnt, dynamic behavior of the cascade was observed. 8 refs., 7 figs., 2 tabs

The current revolution in column technology: how it began, where is it going?

Science.gov (United States)

Gritti, Fabrice; Guiochon, Georges

2012-03-09

This work revisits the exceptionally rapid evolution of the technology of chromatographic columns and the important progress in speed of analysis and resolution power that was achieved over the last ten years. Whereas columns packed with 10 and 5 μm fully porous particles dominated the field for nearly thirty years (1975-2000), it took barely six years to see the commercialization of monolithic silica rods (2000), their raise to fame and decay to oblivion, the development of finer fully porous particles with size down to 1.7 μm (2006), and of sub-3 μm superficially porous particles (2006). Analysis times and plate heights delivered by columns packed with these recent packing materials have then been improved by more than one order of magnitude in this short period of time. This progress has rendered practically obsolete the age-old design of LC instruments. For low molecular weight compounds, analysts can now achieve peak capacities of 40 peaks in about 15s with a hold-up time of the order of 1.5s , in gradient elution, by operating columns packed with sub-3 μm shell particles at elevated temperatures, provided that they use optimized high pressure liquid chromatographs. This is the ultimate limit allowed by modern instruments, which have an extra-column band broadening contribution of 7 μL² at 4.0 mL/min and data acquisition rate of 160 Hz. The best 2.1 mm × 50 mm narrow-bore columns packed with 1.7 μm silica core-shell particles provide peaks that have a variance of 2.1 μL² for k=1. Finally, this work discusses possible ways to accelerate separations and, in the same time perform these separations at the same level of efficiency as they have today. It seems possible to pack columns with smaller particles, probably down to 1 μm and operate them with current vHPLC equipments for separations of biochemicals. Analyses of low molecular weight compounds will require new micro-HPLC systems able to operate 1mm I.D. columns at pressures up to 5 kbar, which

Estimation of Chromatographic Columns Performances using Computer Tomography and CFD Simulations

DEFF Research Database (Denmark)

Schmidt, Irma; Lottes, Florian; Minceva, Mirjana

2011-01-01

The flow inside a chromatographic column depends decisively on the packed bed inside. Non‐destructive X‐ray computed tomography (CT) was applied as a novel measurement technique to visualize the distribution of velocity and axial dispersion coefficients in preparative scale columns. The results...... show, that spherical particles seem to be more efficient than irregular ones in terms of HETP, which has to be partly a result of the more homogeneous flow profile they induce. The prediction of column performance in dependence of the structure of the packed bed was simulated by CFD (Computational...

Optimization of the isotope separation in columns

International Nuclear Information System (INIS)

Kaminskij, V.A.; Vetsko, V.M.; Tevzadze, G.A.; Devdariani, O.A.; Sulaberidze, G.A.

1982-01-01

The general method for the multi-parameter optimization of cascade plants of packed columns is proposed. As an optimization effectiveness function a netcost of the isotopic product is selected. The net cost is comprehensively characterizing the sum total of capital costs for manufacturing the products as well as determining the choice of the most effective directions for capital investments and rational limits of improvement of the products quality. The method is based on main representations of the cascade theory, such as the ideal flow profile and form efficiency as well as mathematical model of the packed column specifying the bonds between its geometric and operating parameters. As a result, the isotopic products cost function could be bound with such parameters as the equilibrium stage height, ultimate packing capacity, its element dimensions, column diameter. It is concluded that the suggested approach to the optimization of isotope separation processes is rather a general one. It permits to solve a number of special problems, such as estimation of advisability of using heat-pump circuits and determining the rational automation level. Besides, by means of the method suggested one can optimize the process conditions with regard to temperature and pressure

Lead Biosorption by Self-Immobilized Rhizopus nigricans Pellets in a Laboratory Scale Packed Bed Column: Mathematical Model and Experiment

Directory of Open Access Journals (Sweden)

Adela Kogej

2010-01-01

Full Text Available The biosorption of lead ions from aqueous solution on a self-immobilized Rhizopus nigricans biomass has been studied. Experiments were performed in a laboratory scale packed bed column at different liquid flow rates and biosorbent bed heights. Recorded experimental breakthrough curves were compared to those predicted by a mathematical model, which was developed to simulate a packed bed biosorption process by a soft, self-immobilized fungal biosorbent. In the range of examined experimental conditions, the biomass characteristics such as pellet porosity and biosorption capacity substantially affected the predicted response curve. General correlations for the estimation of the intra-pellet effective diffusivity, the external mass transfer coefficient, as well as axial dispersion were successfully applied in this biological system with specific mechanical properties. Under the experimental conditions, mass transfer is controlled by the external film resistance, while the intra-pellet mass transfer resistance, as well as the effect of axial dispersion, can be neglected. A new parameter α, the fraction of active biomass, with an average value of α=0.7, was introduced to take into account the specific biomass characteristics, and consequently the observed non-ideal liquid flow through the bed of fungal pellets.

Mass transfer models analysis for the structured packings

International Nuclear Information System (INIS)

Suastegui R, A.O.

1997-01-01

The models that have been developing, to understand the mechanism of the mass transfer through the structured packings, present limitations for their application, existing then uncertainty in order to use them in the chemical industrial processes. In this study the main parameters used in the mass transfer are: the hydrodynamic of the bed of the column, the geometry of the bed, physical-chemical properties of the mixture and the flow regime of the operation between the flows liquid-gas. The sensibility of each one of these parameters generate an arduous work to develop right proposals and good interpretation of the phenomenon. With the purpose of showing the importance of these parameters mentioned in the mass transfer, this work is analyzed the process of absorption for the system water-air, using the models to the structured packings in packed columns. The models selected were developed by Bravo and collaborators in 1985 and 1992, in order to determine the parameters previous mentioned for the system water-air, using a structured packing built in the National Institute of Nuclear Research. In this work is showed the results of the models application and their discussion. (Author)

LIQUID-LIQUID EXTRACTION COLUMNS

Science.gov (United States)

Thornton, J.D.

1957-12-31

This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.

Fiber-based monolithic columns for liquid chromatography.

Science.gov (United States)

Ladisch, Michael; Zhang, Leyu

2016-10-01

Fiber-based monoliths for use in liquid chromatographic separations are defined by columns packed with aligned fibers, woven matrices, or contiguous fiber structures capable of achieving rapid separations of proteins, macromolecules, and low molecular weight components. A common denominator and motivating driver for this approach, first initiated 25 years ago, was reducing the cost of bioseparations in a manner that also reduced residence time of retained components while achieving a high ratio of mass to momentum transfer. This type of medium, when packed into a liquid chromatography column, minimized the fraction of stagnant liquid and resulted in a constant plate height for non-adsorbing species. The uncoupling of dispersion from eluent flow rate enabled the surface chemistry of the stationary phase to be considered separately from fluid transport phenomena and pointed to new ways to apply chemistry for the engineering of rapid bioseparations. This paper addresses developments and current research on fiber-based monoliths and explains how the various forms of this type of chromatographic stationary phase have potential to provide new tools for analytical and preparative scale separations. The different stationary phases are discussed, and a model that captures the observed constant plate height as a function of mobile phase velocity is reviewed. Methods that enable hydrodynamically stable fiber columns to be packed and operated over a range of mobile phase flow rates, together with the development of new fiber chemistries, are shown to provide columns that extend the versatility of liquid chromatography using monoliths, particularly at the preparative scale. Graphical Abstract Schematic representation of a sample mixture being separated by a rolled-stationary phase column, resulting separated peaks shown in the chromatogram.

New Structured Packing CUB for Purification of Exhaust Gases

Directory of Open Access Journals (Sweden)

Irina Novikova

2016-10-01

Full Text Available New structured packing for heat and mass transfer processes named CUB is presented in our article. The packing can be applied in packed towers for exhaust gas cleaning instead random packing, for example, rings type that are the most used in such processes. The advantages of the new packing over random packing are lower pressure drop, capability of purification and as a consequence long-term service of the packing. The researches of intensity of liquid-phase mass-transfer in packed bed depending on liquid spray rate and gas velocity were carried out. Obtained data show that packing CUB is more effective than the most popular type of structured packing under all other conditions being equal. As experimental data shown heat transfer coefficient was up by 17% and mass transfer coefficient was up by 51%. We found out optimal geometry of cross section of the new packing, namely, number of elements and parameters of one element. The new construction of structured packing is applicable for both type of column cross-section round and square.

Gas-solid trickle flow hydrodynamics in a packed column

NARCIS (Netherlands)

Westerterp, K.R.; Kuczynski, M.

1987-01-01

The pressure gradient and the static and the dynamic hold-up have been measured for a system consisting of a Fluid Cracking Catalyst (FCC) of 30–150 × 10−6 m diameter, trickling over a packed bed and with a gas streaming in countercurrent flow. The experiments were carried out at ambient conditions

New proposition on performance evaluation of hydrophobic Pt catalyst packed in trickle bed

International Nuclear Information System (INIS)

Shimizu, Masami; Kitamoto, Asashi; Takashima, Yoichi.

1983-01-01

On the evaluation of the performance of the hydrophobic Pt catalyst packed in the trickle-bed test column, the conventionally defined (Ksub(y)a) and the newly defined (Ksub(f))sub (G) are compared with each other as a measure of the overall D-transfer coefficient. The value of (Ksub(y)a) varies in a wide range in accordance with the length of the test column. On the other hand (Ksub(f))sub (G sub (l = L)) has a finite value in the test column longer than about 0.5 m. By considering the values of ksub(g) and ksub(l) which are the constituents of (Ksub(f))sub (G), it is possible to improve the hydrophobic Pt catalyst trickle bed and to design the H 2 /H 2 O-isotopic exchange trickle-bed column packed with this catalyst. (author)

Experimental investigation of liquid chromatography columns by means of computed tomography

DEFF Research Database (Denmark)

Astrath, D.U.; Lottes, F.; Vu, Duc Thuong

2007-01-01

The efficiency of packed chromatographic columns was investigated experimentally by means of computed tomography (CT) techniques. The measurements were carried out by monitoring tracer fronts in situ inside the chromatographic columns. The experimental results were fitted using the equilibrium di...

Process development of continuous glycerolysis in an immobilized enzyme-packed reactor for industrial monoacylglycerol production

DEFF Research Database (Denmark)

Damstrup, Marianne; Kiil, Søren; Jensen, Anker Degn

2007-01-01

Continuous and easily operated glycerolysis was studied in different lipase-packed columns to evaluate the most potential process set-ups for industrial monoacylglycerol (MAG) production. Practical design-related issues such as enzyme-filling degree, required reaction time, mass transfer investig......Continuous and easily operated glycerolysis was studied in different lipase-packed columns to evaluate the most potential process set-ups for industrial monoacylglycerol (MAG) production. Practical design-related issues such as enzyme-filling degree, required reaction time, mass transfer...

Mass spectrometric protein characterization in proteome analysis using GELoader tip micro-columns packed with various chromatographic material

International Nuclear Information System (INIS)

Larsen, M.R.

2001-01-01

In the early 90'ies mass spectrometry (MS) was introduced as a tool for identifying proteins in protein sequence databases. Since then it has become an integrated tool in protein characterization and is today routinely used to identify proteins separated by gel electrophoresis. A two-tiered mass spectrometric protein identification strategy has recently been proposed. In the first strategy peptide mass maps obtained from the protein of interest are compared with theoretically derived peptide mass maps from proteins in protein sequence databases. If the protein cannot be identified by this strategy, tandem mass spectrometric sequencing is used to generate enough sequence data to identify the protein in protein sequence databases or expressed sequence tag (EST) databases. However, the above strategies primarily identify a protein relatively to the DNA sequence, in which no information about e.g. post-translational modifications (PTMs) is stored. PTMs are known to modify the function, location, solubility and activity of proteins in the cell, and they are therefore very important for understanding living cells. More than 200 different PTMs are known, of which glycosylation, phosphorylation and proteolytic processing are the most common ones. Mass spectrometric analysis of PTMs on gel-separated proteins requires a higher amount of protein than for identification only. In addition, higher sequence coverage from the peptide mass maps or pre-purification of the modified peptides prior to MS analysis, is necessary for detection of putative modified peptides. In this study a multi-tiered strategy, in which GELoader tip micro-columns packed with increasingly more hydrophobic chromatographic material are used in combination with mass spectrometry, is described. The ultimate aim was to gain increased sequence coverage from peptide mixtures derived from gel-separated proteins, in order to locate modified peptides. Graphite powder is described as an alternative to traditional

Finite dipolar hexagonal columns on piled layers of triangular lattice

International Nuclear Information System (INIS)

Matsushita, Katsuyoshi; Sugano, Ryoko; Kuroda, Akiyoshi; Tomita, Yusuke; Takayama, Hajime

2007-01-01

We have investigated, by the Monte Carlo simulation, spin systems which represent moments of arrayed magnetic nanoparticles interacting with each other only by the dipole-dipole interaction. In the present paper we aim the understanding of finite size effects on the magnetic nanoparticles arrayed in hexagonal columns cut out from the close-packing structures or from those with uniaxial compression. In columns with the genuine close-packing structures, we observe a single vortex state which is also observed previously in finite two-dimensional systems. On the other hand in the system with the inter-layer distance set 1/2 times of the close-packing one, we found ground states which depend on the number of layers. The dependence is induced by a finite size effect and is related to a orientation transition in the corresponding bulk system

Evaluation of chromatographic columns packed with semi- and fully porous particles for benzimidazoles separation.

Science.gov (United States)

Gonzalo-Lumbreras, Raquel; Sanz-Landaluze, Jon; Cámara, Carmen

2015-07-01

The behavior of 15 benzimidazoles, including their main metabolites, using several C18 columns with standard or narrow-bore diameters and different particle size and type were evaluated. These commercial columns were selected because their differences could affect separation of benzimidazoles, and so they can be used as alternative columns. A simple screening method for the analysis of benzimidazole residues and their main metabolites was developed. First, the separation of benzimidazoles was optimized using a Kinetex C18 column; later, analytical performances of other columns using the above optimized conditions were compared and then individually re-optimized. Critical pairs resolution, analysis run time, column type and characteristics, and selectivity were considered for chromatographic columns comparison. Kinetex XB was selected because it provides the shortest analysis time and the best resolution of critical pairs. Using this column, the separation conditions were re-optimized using a factorial design. Separations obtained with the different columns tested can be applied to the analysis of specific benzimidazoles residues or other applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pulsing flow in trickle bed columns

NARCIS (Netherlands)

Blok, Jan Rudolf

1981-01-01

In the operation of a packed column with cocurrent downflow of gas and liquid (trickle bed) several flowpatterns can be observed depending on the degree of interaction between gas and liquid. At low liquid and gas flow rates - low interaction - gascontinuous flow occurs. In this flowregime, the

Mini-columns for Conducting Breakthrough Experiments. Design and Construction

Energy Technology Data Exchange (ETDEWEB)

Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ware, Stuart Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-06-11

Experiments with moderately and strongly sorbing radionuclides (i.e., U, Cs, Am) have shown that sorption between experimental solutions and traditional column materials must be accounted for to accurately determine stationary phase or porous media sorption properties (i.e., sorption site density, sorption site reaction rate coefficients, and partition coefficients or K_d values). This report details the materials and construction of mini-columns for use in breakthrough columns to allow for accurate measurement and modeling of sorption parameters. Material selection, construction techniques, wet packing of columns, tubing connections, and lessons learned are addressed.

Inert carriers for column extraction chromatography

International Nuclear Information System (INIS)

Katykhin, G.S.

1978-01-01

Inert carriers used in column extraction chromatography are reviewed. Such carriers are devided into two large groups: hydrophilic carriers which possess high surface energy and are well wetted only with strongly polar liquids (kieselguhrs, silica gels, glasses, cellulose, Al 2 O 3 ) and water-repellent carriers which possess low surface energy and are well wetted with various organic solvents (polyethylene, polytetrafluorethylene polytrifluorochlorethylene). Properties of various carriers are presented: structure, chemical and radiation stability, adsorption properties, extracting agent capacity. The effect of structure and sizes of particles on the efficiency of chromatography columns is considered. Ways of immovable phase deposition on the carrier and the latter's regeneration. Peculiarities of column packing for preparative and continuous chromatography are discussed

Solid foam packings for multiphase reactors: Modelling of liquid holdup and mass transfer

NARCIS (Netherlands)

Stemmet, C.P.; Schaaf, van der J.; Kuster, B.F.M.; Schouten, J.C.

2006-01-01

In this paper, experimental and modeling results are presented of the liquid holdup and gas–liquid mass transfer characteristics of solid foam packings. Experiments were done in a semi-2D transparent bubble column with solid foam packings of aluminum in the range of 5–40 pores per inch (ppi). The

Three versus five micrometer chlorinated polysaccharide-based packings in chiral capillary electrochromatography: performance evaluation.

Science.gov (United States)

Hendrickx, Ans; De Klerck, Katrijn; Mangelings, Debby; Clincke, Lies; Heyden, Yvan Vander

2014-01-01

In this study, a test set of 44 nonacidic compounds was analyzed on four 3 µm chlorinated polysaccharide-based chiral stationary phases with cellulose tris (3-chloro-4-methylphenylcarbamate) (Lux Cellulose-2®; LC2), amylose tris (5-chloro-2-methylphenylcarbamate) (Lux Amylose-2®, LA2), cellulose tris (4-chloro-3-methylphenylcarbamate) (Lux Cellulose-4®; LC4) and cellulose tris (3,5-dichlorophenylcarbamate) (Sepapak-5®, Sp5) as selectors. The analysis times, retention factors, efficiencies and enantioselectivities were compared with the results obtained on their 5 µm analogs. All 3 µm packings, except for LA2, individually separated more compounds than their 5 µm analogs. When the cumulative success rates on the 3 and 5 µm packings were considered, it was observed that they were similar for both particle sizes; the combination of three or four 5 µm columns separated one compound more from the considered test set than that of the same number of 3 µm columns. Furthermore, it was observed that the 3 and 5 µm packings showed some complementarity. Only four compounds were not separated on any of the columns, while the use of only either the 3 or 5 µm columns resulted in 10 and nine not-separated compounds, respectively. The analyses on 5 µm LC2 and Sp5 were faster than on their 3 µm analogs. For LC4 the 3 µm packing showed the shortest analysis times and diverse analysis times for both particle sizes were obtained on LA2. Furthermore, three out of four 3 µm packings, that is, LC2, LC4, and Sp5, were found to be more efficient than their 5 µm analogs. Copyright © 2013 John Wiley & Sons, Ltd.

Heat Transfer Analysis for a Fixed CST Column

International Nuclear Information System (INIS)

Lee, S.Y.

2004-01-01

In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for several alternate column sizes, heat loads of the packed column, engineered cooling systems, and various ambient conditions at the exterior wall of the column have been performed under the reference conditions of the CST-salt solution to assess the impact of those parameters on the peak temperatures of the packed column for a given transient time. The results indicate that a water-coolant pipe at the center of the CST column filled with salt solution is the most effective one among the potential design parameters related to the thermal energy dissipation of decay heat load. It is noted that the cooling mechanism at the wall boundary of the column has significant

Determination of Intrinsic Permeability for Packed Waste of Indonesian Solid Waste

Directory of Open Access Journals (Sweden)

Benno Rahardyan

2010-11-01

Full Text Available Gas permeability and intrinsic permeability are the major parameters to promote aeration for packed waste. The objectives of this research are to identify physical parameters of gas transfer from a various type of packed wastes and examine ventilation design theory for landfill to enhance waste stabilization. Method to determine value of gas permeability and intrinsic permeability for packed waste is by flushing the packed column containing various type and physical characteristics of wastes with an air pump. Permeability was calculated by measuring pressure gradient on sampling points of the column using inclined manometer at distance 10 cm, 23 cm, 46 cm, 69 cm, 92 cm and 115 cm from origin. Gas permeability is specifically relied on physical parameters of wastes as follows, density, moisture content, particle size and gas velocity on the surface of compacted waste layer. Compost has finer pore structure and smaller pore size than leaves as well as mixed organic (65% and inorganic wastes (35%. The experiment found the intrinsic permeability of leaves waste are in the order of 10-11 to 10-8 m2, 10-11 to 10-9 m2 for compost and 10-9 m2 for mixed organic (65% and inorganic wastes (35%.

Characterization of metallic surfaces in phosphorous-bronze ordered packings

International Nuclear Information System (INIS)

Sandru, Claudia; Titescu, Gh.

1997-01-01

Copper and its alloys, particularly the phosphorous bronze, are characterized by a high water wettability as compared with other materials. This feature led to utilization of phosphorous bronze in fabrication of contact elements, a packing type equipping the distillation columns. For heavy water separation by isotopic distillation under vacuum, ordered packings of phosphorous bronze networks were fabricated. The superior performances of these packings are determined by the material and also by the geometrical form and the state of the metallic surface. Thus, a procedure of evaluating the wettability has been developed, based on tests of the network material. The results of the tests constitute a criterion of rating the functional performances of packings, particularly of their efficiencies. Also, investigation techniques of the chemical composition and of the thickness of superficial layer on the packing were developed. It was found that the packing surface presents a layer of about 5-20 μm formed mainly by oxides of copper, tin, and, depending on the packing treatment, of oxides of other elements coming from the treatment agent. The paper presents characterization of phosphorous bronze treated with potassium permanganate, a specific treatment for improving the functional performances of the packings used in the heavy water concentration and re-concentration installations

Approximate transient and long time limit solutions for the band broadening induced by the thin sidewall-layer in liquid chromatography columns.

Science.gov (United States)

Broeckhoven, Ken; Desmet, Gert

2007-11-16

Using a combination of both analytical and numerical techniques, approximate analytical expressions have been established for the transient and long time limit band broadening, originating from the presence of a thin disturbed sidewall layer in liquid chromatography columns, including packed, monolithic as well as microfabricated columns. The established expressions can be used to compare the importance of a thin disturbed sidewall layer with that of other radial heterogeneity effects (such as transcolumn packing density variations due to the relief of packing stresses). The expressions are independent of the actual velocity profile inside the layer as long as the disturbed sidewall layer occupies less than 2.5% of the column width.

HPLC-CUPRAC post-column derivatization method for the determination of antioxidants: a performance comparison between porous silica and core-shell column packing.

Science.gov (United States)

Haque, Syed A; Cañete, Socrates Jose P

2018-01-01

An HPLC method employing a post-column derivatization strategy using the cupric reducing antioxidant capacity reagent (CUPRAC reagent) for the determining antioxidants in plant-based materials leverages the separation capability of regular HPLC approaches while allowing for detection specificity for antioxidants. Three different column types, namely core-shell and porous silica including two chemically different core-shell materials (namely phenyl-hexyl and C18), were evaluated to assess potential improvements that could be attained by changing from a porous silica matrix to a core-shell matrix. Tea extracts were used as sample matrices for the evaluation specifically looking at catechin and epigallocatechin gallate (EGCG). Both the C18 and phenyl-hexyl core-shell columns showed better performance compared to the C18 porous silica one in terms of separation, peak shape, and retention time. Among the two core-shell materials, the phenyl-hexyl column showed better resolving power compared to the C18 column. The CUPRAC post-column derivatization method can be improved using core-shell columns and suitable for quantifying antioxidants, exemplified by catechin and EGCG, in tea samples.

Evaluation of a subsurface oxygenation technique using colloidal gas aphron injections into packed column reactors

International Nuclear Information System (INIS)

Wills, R.A.; Coles, P.

1991-11-01

Bioremediation may be a remedial technology capable of decontaminating subsurface environments. The objective of this research was to evaluate the use of colloidal gas aphron (CGA) injection, which is the injection of micrometer-size air bubbles in an aqueous surfactant solution, as a subsurface oxygenation technique to create optimal growth conditions for aerobic bacteria. Along with this, the capability of CGAs to act as a soil-washing agent and free organic components from a coal tar-contaminated matrix was examined. Injection of CGAs may be useful for remediation of underground coal gasification (UCG) sites. Because of this, bacteria and solid material from a UCG site located in northeastern Wyoming were used in this research. Colloidal gas aphrons were generated and pumped through packed column reactors (PCRS) containing post-burn core materials. For comparison, PCRs containing sand were also studied. Bacteria from this site were tested for their capability to degrade phenol, a major contaminant at the UCG site, and were also used to bioaugment the PCR systems. In this study we examined: (1) the effect of CGA injection on dissolved oxygen concentrations in the PCR effluents, (2) the effect of CGA, H 2 O 2 , and phenol injections on bacterial populations, (3) the stability and transport of CGAs over distance, and (4) CGA injection versus H 2 O 2 injection as an oxygenation technique

New series of paper pack vending machines; Paper pack jido hanbaiki no shin series

Energy Technology Data Exchange (ETDEWEB)

Ohashi, M. [Fuji Denki Reiki Co. Ltd., Tokyo (Japan); Umino, S. [Fuji Electric Co. Ltd., Tokyo (Japan)

1996-07-10

This paper presents series of paper pack vending machines. These machines may be broadly classified into those of cold drinks and of hot and cold drinks depending on the storage temperature of products. The former is the machine for cooling dairy products at 10{degree}C with a combined stacking by direct-stacked racks and chain-multiracks. The latter is provided with divided storing chambers with each chamber selectively cooled or heated. Products in the hot chamber are canned coffee and the like set at 55{degree}C. The temperature control is performed by a microcomputer. The chain-multiracks are provided with advantages such as capability of handling various kinds of container shapes, storing drinks and foods vertically, replacing products by the change of a shelf attachment with one operation, and storing one liter packs by setting pair columns. The direct-stacked racks are provided with advantages such as versatility of handling various kinds of containers and miniaturization of the mechanism other than the storage part. The installation space was reduced by devising the opening and closing of the door. The control part is capable of setting temperatures differently for cans and paper packs. 7 figs., 1 tab.

The Performance of the Trickle Bed Reactor Packed with the Pt/SDBC Catalyst Mixture for the CECE Process

International Nuclear Information System (INIS)

Seungwoo Paek; Do-Hee Ahn; Heui-Joo Choi; Kwang-Rag Kim; Hongsuk Chung; Sung-Paal Yim; Minsoo Lee; Kyu-Min Song; Soon Hwan Sohn

2006-01-01

The CECE (Combined Electrolysis Catalytic Exchange) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE process is composed of an electrolysis cell and a LPCE (Liquid Phase Catalytic Exchange) column. This paper describes the experimental results of the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst for the development of the LPCE column of the CECE process. The hydrophobic Pt/SDBC (Styrene Divinyl Benzene Copolymer) catalyst has been developed by Korean researchers for the LPCE column of WTRF (Wolsong Tritium Removal Facility). An experimental apparatus was constructed for the various experiments with the different parameters, such as hydrogen flow rate, temperature, and the structure of the mixed catalyst column. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring). The performance of the catalyst bed was expressed as an overall rate constant Kya. To improve the performance of the trickle bed, the modification of the catalyst bed design (changing the shape of the catalyst complex and diluting with inert) has been investigated. (author)

Characterization of the efficiency of microbore liquid chromatography columns by van Deemter and kinetic plot analysis.

Science.gov (United States)

Hetzel, Terence; Loeker, Denise; Teutenberg, Thorsten; Schmidt, Torsten C

2016-10-01

The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro-liquid chromatography system. Fully porous, core-shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub-2 μm fully porous as well as the 2.7 μm core-shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56-2.69) before correction for extra-column contribution compared to normal-bore columns. Moreover, the influence of extra-column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub-2 μm fully porous particle packed column for ultra-fast liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mass and heat transfer on B7 ordered packing in hydrogen isotope separation by distillation

International Nuclear Information System (INIS)

Croitoru, Cornelia; Pop, Floarea; Titescu, Gheorghe; Stefanescu, Ioan; Trancota, Dan; Peculea, Marius

2002-01-01

This work presents theoretical and experimental data referring to mass and heat transfer on B7 ordered packing in deuterium isotope separation by distillation. The first part is devoted to the study of mass transfer in hydrogen isotopic distillation while the second one treats the mass and heat transfer in water isotopic distillation. A stationary mathematical model for the mass and heat transfer was developed based on multitubular column model with wet wall. This model allowed the calculation starting from theoretical data of the ordered packing efficiency, expressed by the transfer unit height, TUH. Also, from theoretical data the mass and heat transfer coefficients were determined. A test of the mathematical model was performed with the experimental data obtained from two laboratory installations for hydrogen isotope separation by distillation. From the first installation, experimental data concerning the B7 ordered packing efficiency were obtained for the deuterium separation by cryogenic distillation at the - 250 deg C level. With the second one data referring to the mass and heat transfer on the same packing were obtained for the deuterium separation by water distillation under vacuum at the 60 deg C level. The values of TUH, mass and heat transfer coefficients as theoretically evaluate and experimentally checked are in agreement with the respective values obtained in separation processes in chemical industry. This is the fact which endorses utilization of the model of multitubular column with wet wall for describing the transfer processes in distillation columns equipped with B7 ordered packing

Establishing column batch repeatability according to Quality by Design (QbD) principles using modeling software.

Science.gov (United States)

Rácz, Norbert; Kormány, Róbert; Fekete, Jenő; Molnár, Imre

2015-04-10

Column technology needs further improvement even today. To get information of batch-to-batch repeatability, intelligent modeling software was applied. Twelve columns from the same production process, but from different batches were compared in this work. In this paper, the retention parameters of these columns with real life sample solutes were studied. The following parameters were selected for measurements: gradient time, temperature and pH. Based on calculated results, batch-to-batch repeatability of BEH columns was evaluated. Two parallel measurements on two columns from the same batch were performed to obtain information about the quality of packing. Calculating the average of individual working points at the highest critical resolution (R(s,crit)) it was found that the robustness, calculated with a newly released robustness module, had a success rate >98% among the predicted 3(6) = 729 experiments for all 12 columns. With the help of retention modeling all substances could be separated independently from the batch and/or packing, using the same conditions, having high robustness of the experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Future perspectives of using hollow fibers as structured packings in light hydrocarbon distillation

Energy Technology Data Exchange (ETDEWEB)

Yang, Dali [Los Alamos National Laboratory; Orler, Bruce [Los Alamos National Laboratory; Tornga, Stephanie [Los Alamos National Laboratory; Welch, Cindy [Los Alamos National Laboratory

2011-01-26

Olefin and paraffin are the largest chemical commodities. Furthermore, they are major building blocks for the petrochemical industry. Each year, petroleum refining, consumes 4,500 TBtu/yr in separation energy, making it one of the most energy-intensive industries in the United States). Just considering liquefied petroleum gas (ethane/propane/butane) and olefins (ethylene and propylene) alone, the distillation energy consumption is about 400 TBtu/yr in the US. Since petroleum distillation is a mature technology, incremental improvements in column/tray design will only provide a few percent improvements in the performance. However, each percent saving in net energy use amounts to savings of 10 TBtu/yr and reduces CO{sub 2} emissions by 0.2 MTon/yr. In practice, distillation columns require 100 to 200 trays to achieve the desired separation. The height of a transfer unit (HTU) of conventional packings is typical in the range of 36-60 inch. Since 2006, we had explored using several non-selective membranes as the structured packings to replace the conventional packing materials used in propane and propylene distillation. We obtained the lowest HTU of < 8 inch for the hollow fiber column, which was >5 times shorter than that of the conventional packing materials. In 2008, we also investigated this type of packing materials in iso-/n-butane distillation. Because of a slightly larger relative volatility of iso-/n-butane than that of propane/propylene, a wider and a more stable operational range was obtained for the iso-/n-butane pair. However, all of the experiments were conducted on a small scale with flowrate of < 25 gram/min. Recently, we demonstrated this technology on a larger scale (<250 gram/min). Within the loading range of F-factor < 2.2 Pa{sup 0.5}, a pressure drop on the vapor side is below 50 mbar/m, which suggests that the pressure drop of hollow fibers packings is not an engineering barrier for the applications in distillations. The thermal stability study

Fluoride retardation from quartz sand-packed column tests

Directory of Open Access Journals (Sweden)

Eduardo Usunoff

2009-06-01

Full Text Available Inasmuch as both low and high concentrations of F- in groundwater have different detrimental effects on human health (increased dental caries, and mottled enamel or even severe structural bone deformations, respectively, many efforts have focused on the movement of such anion in aqueous systems. It is so because water drinking is the main intake of F- by humans. This paper presents the results of seven dynamic experiments in which solutions of varying [F-], pH, and flow velocities circulated through columns packed with clean quartz sand. The breakthrough data were analyzed by means of a computer code adapted to the estimation of equilibrium and non-equilibrium solute transport parameters from miscible displacement experiments in a steady-state, uniform flow field using a pulse-type or continuous source. It was found that larger retardation factors (R are associated with low pH, low [F-] in the feed solutions, and larger flow velocities. Such results appear to be related to the form of the F species, the rather weak bond between the adsorbate and the quartz sand, and stronger anion repulsion at low pore velocities. The estimated values for R vary between 1,22 and 1,50, whereas the distribution coefficients were in the range of 0,1 to 0,05 L kg-1. It should be said that the breakthrough curves display hysteresis, leading to a desorption behavior that proceeds faster than the adsorption process.Puesto que tanto valores bajos como altos de F- en las aguas subterráneas tienen efectos adversos en la salud de los humanos (mayor cantidad de caries, y manchas del esmalte dental e incluso deformaciones óseas, respectivamente, han sido muchos los esfuerzos destinados a dilucidar el movimiento de especies fluoradas en ambientes acuosos. Ello es así porque el consumo de agua por parte de seres humanos representa la mayor fuente de ingreso de F-. Este trabajo presenta los resultados de siete experimentos dinámicos en los que soluciones de diferentes [F

Breakthrough properties of chloride ions in columns of lead phosphate hydroxide

International Nuclear Information System (INIS)

Akiba, Kenichi; Hashimoto, Hiroyuki; Mimura, Hitoshi; Shindo, Manabu.

1994-01-01

Breakthrough properties of chloride ion (Cl - ) have been studied by using columns packed with a granular anion-exchanger of lead phosphate hydroxide (Pb 10 (PO 4 ) 6 (OH) 2 , IXE-1000G). The column utilization of the ratio of breakthrough capacity to total capacity increased with decreasing particle size and increasing temperature. The collection of Cl - from a simulated waste solution was improved by the addition of cation-exchange to IXE-1000G; the adsorption capacity of the column of IXE-1000G/IXE-300G (Sb type cation-exchanger) was over 0.16 mmol Cl - /g, yielding a relatively high column utilization of 75%. (author)

Enabling Microliquid Chromatography by Microbead Packing of Microchannels

Science.gov (United States)

Balvin, Manuel; Zheng, Yun

2014-01-01

The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid

Development of an experimental radioisotope based process tomography system for research applications in a cold trickle bed column

International Nuclear Information System (INIS)

Sau, Madhusudan; Kumar, Pravesh; Kumar, Umesh; Acharya, Rajesh; Singh, Gursharan

2009-01-01

In chemical and petrochemical engineering applications, random and structured packing are used in process columns to enhance the heat and mass transfer between two phases. The packing used in such columns is meant to obtain a high specific interfacial area. It is of paramount importance for scale-up and design of trickle bed process columns, to understand and predict the complex multiphase fluid dynamics. In simplified terms, the phase holdup, solid packing distribution in terms of density and gas and liquid velocities among other important parameters need to be qualitatively and quantitatively understood. In the petrochemical industry, many processes are carried out using fixed bed reactors with concurrent upward and downward gas and liquid flows. In order to characterize the liquid and gas flow distribution through a mock-up column, data on planar and volume density distribution using computed tomographic measurements are very helpful. The paper describes the development efforts of a multi-detector 137 Cs radioisotope based in-situ tomography scanner suitable for 600mm dia. cold trickle bed reactor. The development work is at present in progress. The schematics and development of the scanner gantry is described in this paper. (author)

Mass and heat transfer on B7 structured packing in the separation of hydrogen isotopes by distillation

International Nuclear Information System (INIS)

Croitoru, C.; Pop, F.; Titescu, Gh.; Culcer, M.; Iliescu, M.; Stefanescu, I.; Trancota, D.; Peculea, M.

2002-01-01

The paper presents theoretical and experimental data concerning mass and heat transfer on B7 ordered packing, at deuterium separation by distillation. The first section of the paper is dedicated to the mass transfer study of hydrogen distillation, while the second section deals with mass and heat transfer in water distillation. A mathematical model was worked out and compared with experimental data, obtained from two laboratory distillation plants for deuterium separation. From the first plant experimental data concerning B7 ordered packing efficiency of hydrogen cryogenic distillation at 250 deg. C level were obtained. Data concerning mass and heat transfer on the same packing in deuterium separation by water vacuum distillation at 60 deg. C level were obtained in the second plant. HUT values, mass and heat transfer coefficients both theoretically evaluated and experimentally determined were found to be comparable with those obtained from chemical industry separation processes. The fact justifies the use of multi-tubular column model for description of transfer processes in distillation columns equipped with B7 structured packing. (authors)

Evaluating Design Parameters for Breakthrough Curve Analysis and Kinetics of Fixed Bed Columns for Cu(II Cations Using Lignocellulosic Wastes

Directory of Open Access Journals (Sweden)

Zaira Zaman Chowdhury

2014-12-01

Full Text Available A continuous adsorption study for removal of Cu(II cations from wastewater using a fixed-bed column was conducted. A granular carbonaceous activated adsorbent produced by carbonization of the outer rind, or exocarp, of mangostene fruit shell was used for column packing. The effects of feed flow rate, influent cation concentration, and bed depth on the breakthrough curve were investigated at pH 5.5. Experimental analysis confirmed that the breakthrough curves were dependent on flow rate, initial concentration of Cu(II cations, and bed height related to the amount of activated carbon used for column packing. Thomas, Yoon–Nelson, and Adams–Bohart models were applied to analyze the breakthrough curves at different conditions. Linear regression analysis of experimental data demonstrated that Thomas and Yoon–Nelson models were appropriate to explain the breakthrough curve, while the Adams–Bohart model was only applicable to predict the initial part of the dynamic process. It was concluded that the column packed with fruit rind based activated carbon can be used to treat Cu(II-enriched wastewater.

Pressure drop effects on selectivity and resolution in packed-column supercritical fluid chromatography

NARCIS (Netherlands)

Lou, X.W.; Janssen, J.G.M.; Snijders, H.M.J.; Cramers, C.A.M.G.

1996-01-01

The influence of pressure drop on retention, selectivity, plate height and resolution was investigated systematically in packed supercritical fluid chromatography (SFC) using pure carbon dioxide as the mobile phase. Numerical methods developed previously which enabled the prediction of pressure

Successive pretreatment and enzymatic saccharification of sugarcane bagasse in a packed bed flow-through column reactor aiming to support biorefineries.

Science.gov (United States)

Terán-Hilares, R; Reséndiz, A L; Martínez, R T; Silva, S S; Santos, J C

2016-03-01

A packed bed flow-through column reactor (PBFTCR) was used for pretreatment and subsequent enzymatic hydrolysis of sugarcane bagasse (SCB). Alkaline pretreatment was performed at 70 °C for 4h with fresh 0.3M NaOH solution or with liquor recycled from a previous pretreatment batch. Scheffersomyces stipitis NRRL-Y7124 was used for fermentation of sugars released after enzymatic hydrolysis (20 FPU g(-1) of dry SCB). The highest results for lignin removal were 61% and 52%, respectively, observed when using fresh NaOH or the first reuse of the liquor. About 50% of cellulosic and 57% of hemicellulosic fractions of pretreated SCBs were enzymatically hydrolyzed and the maximum ethanol production was 23.4 g L(-1) (ethanol yield of 0.4 gp gs(-1)), with near complete consumption of both pentoses and hexoses present in the hydrolysate during the fermentation. PBFTCR as a new alternative for SCB-biorefineries is presented, mainly considering its simple configuration and efficiency for operating with a high solid:liquid ratio. Copyright © 2015 Elsevier Ltd. All rights reserved.

Admittance Scanning for Whole Column Detection.

Science.gov (United States)

Stamos, Brian N; Dasgupta, Purnendu K; Ohira, Shin-Ichi

2017-07-05

Whole column detection (WCD) is as old as chromatography itself. WCD requires an ability to interrogate column contents from the outside. Other than the obvious case of optical detection through a transparent column, admittance (often termed contactless conductance) measurements can also sense changes in the column contents (especially ionic content) from the outside without galvanic contact with the solution. We propose here electromechanically scanned admittance imaging and apply this to open tubular (OT) chromatography. The detector scans across the column; the length resolution depends on the scanning velocity and the data acquisition frequency, ultimately limited by the physical step resolution (40 μm in the present setup). Precision equal to this step resolution was observed for locating an interface between two immiscible liquids inside a 21 μm capillary. Mechanically, the maximum scanning speed was 100 mm/s, but at 1 kHz sampling rate and a time constant of 25 ms, the highest practical scan speed (no peak distortion) was 28 mm/s. At scanning speeds of 0, 4, and 28 mm/s, the S/N for 180 pL (zone length of 1.9 mm in a 11 μm i.d. column) of 500 μM KCl injected into water was 6450, 3850, and 1500, respectively. To facilitate constant and reproducible contact with the column regardless of minor variations in outer diameter, a double quadrupole electrode system was developed. Columns of significant length (>1 m) can be readily scanned. We demonstrate its applicability with both OT and commercial packed columns and explore uniformity of retention along a column, increasing S/N by stopped-flow repeat scans, etc. as unique applications.

Effects of modifiers in packed and open-tubular supercritical fluid chromatography

NARCIS (Netherlands)

Janssen, J.G.M.; Schoenmakers, P.J.; Cramers, C.A.M.G.

1991-01-01

The applicability of packed and open columns for supercritical fluid chromatography using pure carbon dioxide for the elution of a number of selected test components was investigated. It is showns that the number of solutes that can be eluted as symmetrical peaks is much larger in open-tubular

Transient methods to characterize flows and mass transfer in a packed column by tracers; Methodes transitoires de caracterisation des ecoulements et du transfert de masse dans une colonne a garnissage a l'aide de traceurs

Energy Technology Data Exchange (ETDEWEB)

Perrin, S.

1998-06-11

The aim of this study is to propose a packed column characterization method in the form of phases flows and mass transfer model, in which the parameters are estimated by transient technique. After a bibliographic study a model is performed and validated. It allows efficiency and precision in the parameters choice. Two tracer techniques have been implemented: they show interesting possibilities of flow diagnosis. (A.L.B.)

Absorption column working study for iodine formed in spent fuel reprocessing plant gaseous effluents: hydrodynamic and mass transfer

International Nuclear Information System (INIS)

Vignau, B.

1986-09-01

The hydrodynamic and matter transfer parameters has been studied on absorption columns destined to trap iodine issued of spent fuel reprocessing plants. These columns have different packing - Raschig rings (glass, ceramic, PVC, steel) - Berl saddles (ceramic) - Weaved metallic thread (steel). The effect of dimension and of packing structure on gas pressure drop and on liquid holdup has been evaluated. The partial transfer coefficients of I 2 -Air-NaOH system has been the object of an experimental study. This system can be simulated by CO 2 -Air-NaOH system [fr

Fluid flow profile in a packed bead column using residence time curves and radiotracer techniques

Energy Technology Data Exchange (ETDEWEB)

Almeida, Ana Paula F. de; Gonçalves, Eduardo Ramos; Brandão, Luis Eduardo B.; Salgado, Cesar M., E-mail: anacamiqui@gmail.com, E-mail: egoncalves@con.ufrj.br, E-mail: brandao@ien.gov.br, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

Filling columns are extremely important in the chemical industry and are used for purification, separation and treatment processes of gas or liquid mixtures. The objective of this work is to study the hydrodynamics of the fluid for a characterization of aqueous phase flow patterns in the filling column, associating with the methodology of the Curves of Residence Time Distribution (RTD) to analyze and associate theoretical models that put as conditions column operating. RTD can be obtained by using the pulse-stimulus response technique which is characterized by the instantaneous injection of a radiotracer into the system input. In this work, 68Ga was used as radiotracer. Five shielded and collimated NaI (Tl) 1 x 1″ scintillator detectors were suitably positioned to record the movement of the radiotracer's path in the conveying line and filling column. Making possible the analysis of the RTD curve in the regions of interest. With the data generated by the NaI (Tl) detectors with the passage of the radiotracer in the transport line and inside the column, it was possible to evaluate the flow profile of the aqueous phase and to identify operational failures, such as internal conduit and the existence of a retention zone in the inside the column. Theoretical models were used for different flow flows: the piston flow and perfect mixing. (author)

Fluid flow profile in a packed bead column using residence time curves and radiotracer techniques

International Nuclear Information System (INIS)

Almeida, Ana Paula F. de; Gonçalves, Eduardo Ramos; Brandão, Luis Eduardo B.; Salgado, Cesar M.

2017-01-01

Filling columns are extremely important in the chemical industry and are used for purification, separation and treatment processes of gas or liquid mixtures. The objective of this work is to study the hydrodynamics of the fluid for a characterization of aqueous phase flow patterns in the filling column, associating with the methodology of the Curves of Residence Time Distribution (RTD) to analyze and associate theoretical models that put as conditions column operating. RTD can be obtained by using the pulse-stimulus response technique which is characterized by the instantaneous injection of a radiotracer into the system input. In this work, 68Ga was used as radiotracer. Five shielded and collimated NaI (Tl) 1 x 1″ scintillator detectors were suitably positioned to record the movement of the radiotracer's path in the conveying line and filling column. Making possible the analysis of the RTD curve in the regions of interest. With the data generated by the NaI (Tl) detectors with the passage of the radiotracer in the transport line and inside the column, it was possible to evaluate the flow profile of the aqueous phase and to identify operational failures, such as internal conduit and the existence of a retention zone in the inside the column. Theoretical models were used for different flow flows: the piston flow and perfect mixing. (author)

Measurement of capacity coefficient of inclined liquid phase catalytic exchange column for tritiated water processing

International Nuclear Information System (INIS)

Yamai, Hideki; Konishi, Satoshi; Yamanishi, Toshihiko; Okuno, Kenji

1994-01-01

Liquid phase catalytic exchange (LPCE) is effective method for enrichment and removal of tritium from tritiated water. Capacity coefficients of operating LPCE column that are essential to evaluate column performance were measured. Experiments were performed with short catalyst packed columns and effect of inclination was studied. Method for evaluation of capacity coefficients was established from measurement of isotope concentration of liquid, vapor, gas phases at the two ends of the column. The capacity coefficients were measured under various superficial gas velocities. Feasibility study of helical columns with roughened inner surface was performed with short inclined columns. The column performance was not strongly affected by the inclination. The result indicates technological feasibility of helical LPCE column, that is expected to have operation stability and reduced height

Compressibility effects in packed and open tubular gas and supercritical fluid chromatography

NARCIS (Netherlands)

Janssen, J.G.M.; Snijders, H.M.J.; Cramers, C.A.; Schoenmakers, P.J.

1992-01-01

The influence of the pressure drop on the efficiency and speed of anal. in packed and open tubular supercrit. fluid chromatog. (SFC) is described: methods previously developed to describe the effects of mobile phase compressibility on the performance of open tubular columns in SFC have been extended

ANALYSIS OF TRICKLE BED AND PACKED BUBBLE COLUMN BIOREACTORS FOR COMBINED CARBON OXIDATION AND NITRIFICATION

Directory of Open Access Journals (Sweden)

Iliuta I.

2002-01-01

Full Text Available Biological removal of nitrogen and carbon by combined nitrification-oxidation in gas-liquid trickle-bed reactors (TBRs and packed bubble columns (PBCs was analyzed theoretically using a transient two-dimensional model. The model describes TBR and PBC performances at steady state as well as their transient response to a pulse or step increase in inlet methanol and NH4+-nitrogen concentrations. The hydrodynamic parameters were determined from residence time distribution measurements, using an imperfect pulse method for time-domain analysis of nonideal pulse tracer response. A transient diffusion model of the tracer in the porous particle coupled with the piston-dispersion-exchange model was used to interpret the residence time distribution curves obtained. Gas-liquid mass transfer parameters were determined by a stationary method based on the least-squares fit of the calculated concentration profiles in gas phase to the experimental values. Analysis of steady-state performances showed that under like operating conditions, the TBR outperforms the PBC in terms of conversions. A pulse change in the inlet methanol or NH4+-nitrogen concentration causes a negligible transient change in the outlet methanol concentration and a negligible or high transient change in the outlet NH4+-nitrogen concentration. A step change in the inlet methanol concentration causes the negligible transient change in the methanol outlet concentration and a relatively important transient change in the NH4+-nitrogen outlet concentration. A step increase in the NH4+-nitrogen inlet concentration induces a drastic transient change in the NH4+-nitrogen outlet concentration but a negligible transient change in the methanol outlet concentration.

Carbon dioxide degassing in fresh and saline water I: Degassing performance of a cascade column

DEFF Research Database (Denmark)

Moran, Damian

2010-01-01

A study was undertaken to measure carbon dioxide degassing in a cascade column operating with both fresh (0‰) and saline water (35‰ NaCl) at 15 °C. The cascade column contained bio-block type packing material, was 1.7 m long in each dimension, and was tested both with and without countercurrent a...

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

International Nuclear Information System (INIS)

Watanabe, S; Sano, Y.; Nomura, K.; Koma, Y.; Okamoto, Y.

2015-01-01

The extraction chromatography technology is one of the promising methods for the partitioning of minor actinides (Am and Cm) from spent nuclear fuels. In the extraction chromatography system, the accumulation of hydrogen gas in the chromatography column is suspected to lead to fire or explosion. In order to prevent hazardous accidents, it is necessary to evaluate behaviors of gas radiolytically generated inside the column. In this study, behaviors of gas inside the extraction chromatography column were investigated through experiments and Computation Fluid Dynamics (CFD) simulation. N_2 gas once accumulated as bubbles in the packed bed was hardly discharged by the flow of mobile phase. However, the CFD simulation and X-ray imaging on γ-ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and then discharged. (authors)

Ideal versus real automated twin column recycling chromatography process.

Science.gov (United States)

Gritti, Fabrice; Leal, Mike; McDonald, Thomas; Gilar, Martin

2017-07-28

The full baseline separation of two compounds (selectivity factors αchromatography is used to confirm that the speed-resolution performance of the TCRSP is intrinsically superior to that of the single-column process. This advantage is illustrated in this work by developing an automated TCRSP for the challenging separation of two polycyclic aromatic hydrocarbon (PAH) isomers (benzo[a]anthracene and chrysene) in the reversed-phase retention mode at pressure smaller than 5000psi. The columns used are the 3.0mm×150mm column packed with 3.5μm XBridge BEH-C 18 material (α=1.010) and the 3.0mm or 4.6mm×150mm columns packed with the same 3.5μm XSelect HSST 3 material (α=1.025). The isocratic mobile phase is an acetonitrile-water mixture (80/20, v/v). Remarkably, significant differences are observed between the predicted retention times and efficiencies of the ideal TCRSP (given by the number of cycles multiplied by the retention time and efficiency of one column) and those of the real TCRSP. The fundamental explanation lies in the pressure-dependent retention of these PAHs or in the change of their partial molar volume as they are transferred from the mobile to the stationary phase. A revisited retention and efficiency model is then built to predict the actual performance of real TCRSPs. The experimental and calculated resolution data are found in very good agreement for a change, Δv m =-10cm 3 /mol, of the partial molar volume of the two PAH isomers upon transfer from the acetonitrile-water eluent mixture to the silica-C 18 stationary phase. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of nitrate, ammonia and phosphate from aqueous solutions in packed bed filter using biochar augmented sand media

Directory of Open Access Journals (Sweden)

El Hanandeh Ali

2017-01-01

Full Text Available Nutrients from wastewater are a major source of pollution because they can cause significant impact on the ecosystem. Accordingly, it is important that the nutrient concentrations are kept to admissible levels to the receiving environment. Often regulatory limits are set on the maximum allowable concentrations in the effluent. Therefore, wastewater must be treated to meet safe levels of discharge. In this study, laboratory investigation of the efficiency of packed bed filters to remove nitrate, ammonium and phosphate from aqueous solutions were conducted. Sand and sand augmented with hydrochloric acid treated biochar (SBC were used as packing media. Synthetic wastewater solution was prepared with PO43−, NO3−, NH4+ concentrations 20, 10, 50 mg/L, respectively. Each experiment ran for a period of five days; samples from the effluent were collected on alternate days. All experiments were duplicated. Over the experiment period, the average removal efficiency of PO43−, NO3−, NH4+ were 99.2%, 72.9%, 96.7% in the sand packed columns and 99.2%, 82.3%, 97.4% in the SBC packed columns, respectively. Although, the presence of biochar in the packing media had little effect on phosphate and ammonium removal, it significantly improved nitrate removal.

Development Of ABEC Column For Separation Of Tc-99 From Northstar Dissolved Target Solution

Energy Technology Data Exchange (ETDEWEB)

Stepinski, Dominique C. [Argonne National Lab. (ANL), Argonne, IL (United States); Bennett, Megan E. [Argonne National Lab. (ANL), Argonne, IL (United States); Naik, Seema R. [Argonne National Lab. (ANL), Argonne, IL (United States); ling, lei [Argonne National Lab. (ANL), Argonne, IL (United States); Wang, N-H. Linda [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-12-01

Batch and column breakthrough experiments were performed to determine isotherms and mass-transfer parameters for adsorption of Tc on aqueous biphasic extraction chromatographic (ABEC) sorbent in two solutions: 200 g/L Mo, 5.1 M K⁺, 1 M OH^-, and 0.1 M NO₃^- (Solution A) and 200 g/L Mo, 9.3 M K⁺, 5 M OH^-, and 0.1 M NO₃^- (Solution B). Good agreement was found between the isotherm values obtained by batch and column breakthrough studies for both Solutions A and B. Potassium-pertechnetate intra-particle diffusivity on ABEC resin was estimated by VERSE simulations, and good agreement was found among a series of column-breakthrough experiments at varying flow velocities, column sizes, and technetium concentrations. However, testing of 10 cc cartridges provided by NorthStar with Solutions A and B did not give satisfactory results, as significant Tc breakthrough was observed and ABEC cartridge performance varied widely among experiments. These different experimental results are believed to be due to inconsistent preparation of the ABEC resin prior to packing and/or inconsistent packing.

The system uranyl nitrate-dietyl ether-water. Extraction by water in spray and packed columns from uranyl nitrate-either solutions; El sistema nitrato de uranilo-eter dietilico-agua, extraccion de nitrato de uranilo con agua a partir de disoluciones etereas en columnas de pulverizacion y de relleno

Energy Technology Data Exchange (ETDEWEB)

Perez Luina, A; Gutierrez Jodra, L

1960-07-01

This paper is a continuation of the one published in Chemical Engineering Progress. Symposium Series, 50, n. 12, 127 (1954). New runs for spray columns, are given and other concentrations in uranyl nitrate for the packed columns. New correlations for the overall H.T.U. are also given. The individual H.T.U. have been grapycally calculated and show that the film resistances have similar values, being independent of the concentration of the ether phase. (Author) 24 refs.

Multi-column adsorption systems with condenser for tritiated water vapor removal

International Nuclear Information System (INIS)

Kotoh, Kenji; Kudo, Kazuhiko

1996-01-01

Two types of multi-column adsorption system are proposed as the system for removal of tritiated moisture from tritium process gases or/and handling room atmospheres. The types are of recycle use of adsorption columns, and are composed of twin or triplet columns and one condenser which is used for collecting the adsorbed moisture from columns in desorption process. The systems utilize the dry gas from a working column as the purge gas for regenerating a saturated column and appropriate an active column for recovery of the tritiated moisture passing through the condenser. Each column hence needs the additional amount of adsorbent for collecting the moisture from the condenser. In the modeling and design of an adsorption column, it is primary to estimate the necessary amount of a candidate adsorbent for its packed-bed. The performance of the proposed systems is examined here by analyzing the dependence of the necessary amount of adsorbent for their columns on process operational conditions and adsorbent moisture-adsorption characteristics. The result shows that the necessary amount is sensitive to the types of adsorption isotherm, and suggests that these systems should employ adsorbents which exhibit the Langmuir-type isotherms. (author)

Surface Characterization of Some Novel Bonded Phase Packing Materials for HPLC Columns Using MAS-NMR Spectroscopy

Directory of Open Access Journals (Sweden)

Jude Abia

2015-03-01

Full Text Available Information on the surface properties of three novel chemically bonded phase packing materials for High performance liquid chromatography (HPLC were obtained using spectra obtained by solid state cross-polarization (CP magic-angle spinning (MAS nuclear magnetic resonance (NMR spectroscopic experiments for the 29Si, and 13C nuclei. These packing materials were: Cogent bidentate C18 bonded to type-C silica, hybrid packing materials XTerra MS C18, and XBridge Prep. C18. The spectra obtained using cross-polarization magic angle spinning (CP-MAS on the Cogent bidentate C18 bonded to type-C silica show the surface to be densely populated with hydride groups (Si-H, with a relative surface coverage exceeding 80%. The hybrid packing materials XTerra and XBridge gave spectra that reveal the silicon atoms to be bonded to organic moieties embedded in the molecular structure of these materials with over 90% of the alkyl silicon atoms found within the completely condensed silicon environments. The hydrolytic stability of these materials were investigated in acidic aqueous solutions at pHs of 7.0 and 3.0, and it was found that while the samples of XTerra and XBridge were not affected by hydrolysis at this pH range, the sample of Cogent lost a significant proportion of its Si-H groups after five days of treatment in acidic aqueous solution.

Application of Nanofiber-packed SPE for Determination of Urinary 1-Hydroxypyrene Level Using HPLC.

Science.gov (United States)

Ifegwu, Okechukwu Clinton; Anyakora, Chimezie; Chigome, Samuel; Torto, Nelson

2014-01-01

It is always desirable to achieve maximum sample clean-up, extraction, and pre-concentration with the minimum possible organic solvent. The miniaturization of sample preparation devices was successfully demonstrated by packing 10 mg of 11 electrospun polymer nanofibers into pipette tip micro column and mini disc cartridges for efficient pre-concentration of 1-hydroxypyrene in urine samples. 1-hydroxypyrene is an extensively studied biomarker of the largest class of chemical carcinogens. Excretory 1-hydroxypyrene was monitored with HPLC/fluorescence detector. Important parameters influencing the percentage recovery such as fiber diameter, fiber packing amount, eluent, fiber packing format, eluent volume, surface area, porosity, and breakthrough parameters were thoroughly studied and optimized. Under optimized condition, there was a near perfect linearity of response in the range of 1-1000 μg/L with a coefficient of determination (r (2)) between 0.9992 and 0.9999 and precision (% RSD) ≤7.64% (n = 6) for all the analysis (10, 25, and 50 μg/L). The Limit of detection (LOD) was between 0.022 and 0.15 μg/L. When compared to the batch studies, both disc packed nanofiber sorbents and pipette tip packed sorbents exhibited evident dominance based on their efficiencies. The experimental results showed comparable absolute recoveries for the mini disc packed fibers (84% for Nylon 6) and micro columns (80% for Nylon 6), although the disc displayed slightly higher recoveries possibly due to the exposure of the analyte to a larger reacting surface. The results also showed highly comparative extraction efficiencies between the nanofibers and conventional C-18 SPE sorbent. Nevertheless, miniaturized SPE devices simplified sample preparation, reducing back pressure, time of the analysis with acceptable reliability, selectivity, detection levels, and environmental friendliness, hence promoting green chemistry.

Radiotracer Imaging of Sediment Columns

Science.gov (United States)

Moses, W. W.; O'Neil, J. P.; Boutchko, R.; Nico, P. S.; Druhan, J. L.; Vandehey, N. T.

2010-12-01

Nuclear medical PET and SPECT cameras routinely image radioactivity concentration of gamma ray emitting isotopes (PET - 511 keV; SPECT - 75-300 keV). We have used nuclear medical imaging technology to study contaminant transport in sediment columns. Specifically, we use Tc-99m (T1/2 = 6 h, Eγ = 140 keV) and a SPECT camera to image the bacteria mediated reduction of pertechnetate, [Tc(VII)O4]- + Fe(II) → Tc(IV)O2 + Fe(III). A 45 mL bolus of Tc-99m (32 mCi) labeled sodium pertechnetate was infused into a column (35cm x 10cm Ø) containing uranium-contaminated subsurface sediment from the Rifle, CO site. A flow rate of 1.25 ml/min of artificial groundwater was maintained in the column. Using a GE Millennium VG camera, we imaged the column for 12 hours, acquiring 44 frames. As the microbes in the sediment were inactive, we expected most of the iron to be Fe(III). The images were consistent with this hypothesis, and the Tc-99m pertechnetate acted like a conservative tracer. Virtually no binding of the Tc-99m was observed, and while the bolus of activity propagated fairly uniformly through the column, some inhomogeneity attributed to sediment packing was observed. We expect that after augmentation by acetate, the bacteria will metabolically reduce Fe(III) to Fe(II), leading to significant Tc-99m binding. Imaging sediment columns using nuclear medicine techniques has many attractive features. Trace quantities of the radiolabeled compounds are used (micro- to nano- molar) and the half-lives of many of these tracers are short (Image of Tc-99m distribution in a column containing Rifle sediment at four times.

Activity behavior of a HPLC column including α-chymotrypsin immobilized monosized-porous particles

International Nuclear Information System (INIS)

Bilici, Z.; Camli, S.T.; Unsal, E.; Tuncel, A.

2004-01-01

In this study, a polymer-based, α-chymotrypsin (CT) immobilized HPLC column was prepared as a potential material for affinity-HPLC and chiral separation applications. Monosized-macroporous particles were synthesized as the support material by a relatively new polymerization protocol, the so-called, 'modified seeded polymerization'. The particles were obtained in the form of styrene-glycidyl methacrylate- divinylbenzene terpolymer approximately 11 μm in size. The particles were treated with aqueous ammonia to have primary amine groups on the porous surface. The amine functionalized particles were reacted by glutaraldehyde and the enzyme, CT, was covalently attached. CT carrying monosized-porous particles were slurry packed into the HPLC column 50 mmx4.6 mm in size. Since the activity behavior of immobilized CT played an important role in the enantiomeric separations performed by similar columns, the enzymatic activity behavior of the column produced by our protocol was determined. For this purpose, HPLC column was used as a packed bed reactor and the enzymatic reaction was continuously followed by measuring the absorbance of the output flow by the UV-detector of HPLC. S-shaped absorbance-time curves were obtained by monitoring the reactor output both in dynamic and steady-state periods. The columns with relatively lower immobilized enzyme content were more sensitive to the changes in the operating conditions and responded with more appreciable substrate conversion changes. The maximum reaction rate of the immobilized enzyme was estimated as approximately 25% of the free one by the mathematical model describing the activity behavior of the column. No significant loss was observed in the activity of the immobilized enzyme during the course of the experiments

Use of a pulsed column with discs and crowns for uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

1982-04-01

The physico-chemistry of the system phosphoric acid-uranium-dioctylpyrophosphoric acid is studied for the determination of analytical methods and extraction parameters (oxidation state of uranium and iron, phosphorus concentration, extractant concentration). Extraction is then realized on a pilot scale with a liquid-liquid extraction column 4m high and of 50 mm in diameter with a column packing made of discs and crowns. Column efficiency is evaluated by studying uranium transfer as a function of operating conditions. The results obtained are extrapolated to an industrial scale and a comparative economic evaluation is made between a pulsed column and a mixer-settler [fr

High-efficiency liquid chromatography on conventional columns and instrumentation by using temperature as a variable I. Experiments with 25 cm x 4.6 mm I.D., 5 microm ODS columns.

Science.gov (United States)

Lestremau, François; Cooper, Andrew; Szucs, Roman; David, Frank; Sandra, Pat

2006-03-24

High plate numbers were obtained in conventional LC by coupling columns and by using temperature to reduce the viscosity of the mobile phase. At 80 degrees C up to eight columns of 25 cm x 4.6 mm I.D. packed with 5 microm ODS particles could be coupled generating 180,000 effective plates while the pressure drop was only 350bar. For routine work, a set of four columns is preferred. The analysis times on one column operated at 30 degrees C and 1 mL/min flow rate and on four columns at 80 degrees C and 2 mL/min flow rate are the same in isoeluotropic conditions while the resolution is doubled. Multicolumn systems were successfully applied in isocratic and gradient mode for the analysis of pharmaceutical and environmental samples.

Tritium Isotope Separation Using Adsorption-Distillation Column

International Nuclear Information System (INIS)

Fukada, Satoshi

2005-01-01

In order to miniaturize the height of a distillation tower for the detritiation of waste water from fusion reactors, two experiments were conducted: (1) liquid frontal chromatography of tritium water eluting through an adsorption column and (2) water distillation using a column packed with adsorbent particles. The height of the distillation tower depends on the height equivalent to a theoretical plate, HETP, and the equilibrium isotope separation factor, α H-T equi . The adsorption action improved not only HETP but also α H-T equi . Since the adsorption-distillation method proposed here can shorten the tower height with keeping advantages of the distillation, it may bring an excellent way for miniaturizing the distillation tower to detritiate a large amount of waste water from fusion reactors

A cryogenic distillation column cascade for a fusion reactor

International Nuclear Information System (INIS)

Kinoshita, M.

1984-01-01

A cryogenic distillation column cascade composed of only two columns is proposed. Compared with the Tritium Systems Test Assembly (TSTA) cascade, the tritium inventory is about 1.5 times more and the packed height of the highest column increases by about 40%. However, the number of the columns is halved with the separation performance unchanged. The number of the instruments needed and the number of the process parameters to be monitored are also reduced. Unlike in the case of the TSTA cascade, the performance of the proposed cascade is not subject to the flow rate of the neutral beam injector recycle stream. The high performance can be maintained even if the protium percentage in the raw fuel input increases significantly (e.g., from 1 to 3%), just by adjusting the flow rates of the top, bottom, and side streams. Because of this great flexibility, it is worthwhile to build and study the proposed cascade as a possible alternative to the TSTA cascade

RpeakChrom: Novel R package for the automated characterization and optimization of column efficiency in high-performance liquid chromatography analysis.

Science.gov (United States)

Peris-Díaz, Manuel David; Alcoriza-Balaguer, Maria Isabel; García-Cañaveras, Juan Carlos; Santonja, Francisco; Sentandreu, Enrique; Lahoz, Agustín

2017-11-01

Characterization of chromatographic columns using the traditional van Deemter method is limited by the necessity of calculating extra-column variance, issue particularly relevant when modeling asymmetrical peaks eluted from monolithic columns. A novel R package that implements Parabolic Variance Modified Gaussian approach for accurate peak modeling, van Deemter equation and two alternatives approaches, based on van Deemter, has been developed to calculate the height equivalent to a theoretical plate (HETP). To assess package capabilities conventional packed reverse-phase and monolithic HPLC columns were characterized. Peaks eluted from the monolithic column showed a high value of factor asymmetry due, in part, to the contribution of extra-column factors. Such deviation can be circumvented by the two alternatives approaches implemented in the R-package. Furthermore, increased values of eddy diffusion and mass transfer kinetics terms in HETP were observed for the packed column, while accuracy was below 9% in all cases. These results showed the usefulness of the R-package for both modeling chromatographic peaks and assessing column efficiency. The RpeakChrom package could become a helpful tool for testing new stationary phases during column development and to evaluate column during its lifetime. This R tool is freely available from CRAN (https://CRAN.R-project.org/package=RpeakChrom). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Column Chromatography To Obtain Organic Cation Sorption Isotherms.

Science.gov (United States)

Jolin, William C; Sullivan, James; Vasudevan, Dharni; MacKay, Allison A

2016-08-02

Column chromatography was evaluated as a method to obtain organic cation sorption isotherms for environmental solids while using the peak skewness to identify the linear range of the sorption isotherm. Custom packed HPLC columns and standard batch sorption techniques were used to intercompare sorption isotherms and solid-water sorption coefficients (Kd) for four organic cations (benzylamine, 2,4-dichlorobenzylamine, phenyltrimethylammonium, oxytetracycline) with two aluminosilicate clay minerals and one soil. A comparison of Freundlich isotherm parameters revealed isotherm linearity or nonlinearity was not significantly different between column chromatography and traditional batch experiments. Importantly, skewness (a metric of eluting peak symmetry) analysis of eluting peaks can establish isotherm linearity, thereby enabling a less labor intensive means to generate the extensive data sets of linear Kd values required for the development of predictive sorption models. Our findings clearly show that column chromatography can reproduce sorption measures from conventional batch experiments with the benefit of lower labor-intensity, faster analysis times, and allow for consistent sorption measures across laboratories with distinct chromatography instrumentation.

The employment of cellulose pressure columns for the chromatographic separation of radioactive nuclides

International Nuclear Information System (INIS)

Meier, H.; Zimmerhackl, E.; Unger, E.; Zeitler, G.; Albrecht, W.; Boesche, D.; Hecker, W.; Menge, P.

1975-01-01

A study was made of the separation properties of cellulose pressure columns operating at a slight over-pressure of around 1 atmosphere, with respect to the length of the column packing, the flow rate, and the load. The optimal separation stage heights of the columns are situated at H=0.16 mm. Since as a consequence of the favorable separation stage heights observed at column lengths of 3 to 7 cm, separation stage numbers of 200 to 400 are attained, and hence it is possible to attain separations within several minutes with flow rates of 1 ml/min. The choice of the mobile phase is made easier by the fact that paper chromatographic Rsub(f)-values can be transferred to the cellulose pressure column with the aid of a transfer function. (author)

Influence of packing motives on charge Carrier mobility in perylene tetracarboxdiimide derivatives

Energy Technology Data Exchange (ETDEWEB)

May, Falk; Andrienko, Denis [Max-Planck Institute for Polymer Research, Mainz (Germany); Marcon, Valentina [Center of Smart Interfaces, Darmstadt (Germany)

2010-07-01

Discotic mesophases are known for their ability to self-assemble into columnar structures and can serve as semiconducting molecular wires. Charge carrier mobility along these wires strongly depends on molecular packing which is controlled by intermolecular interactions. In this work we compare the influence of side chains on the packing motives of perylene tetracarboxdiimide (PDI) derivatives. Two different (alkyl and glycol) side chains are considered. We first establish how the packing of side chains affects the molecular orientation within the columns using molecular dynamics. Then, using the high temperature non-adiabatic limit of Marcus theory for hopping rates and solving the rate equation for charge transport, we analyze the link between the secondary structure and charge carrier mobility. This analysis eventually provides a pathway to rational design of columnar assemblies of PDI derivatives with high charge mobilities.

Pulse column hydrodynamics for liquid-liquid extraction with truncated-disc packing

International Nuclear Information System (INIS)

Bracou, H.; Hanssens, A.

1993-01-01

The experimental installation is composed of a stainless steel truncated disc packing with 25% of axial transparency, 25 mm of distance between the plates and 50 mm of diameter (DT 25/25/50 stainless steel). The phase system used during these tests is the hydrogenated tetra-propylene (HTP dispersed phase) /water (continuous phase) in continuous aqueous operating ''FAC'' method. The aim of this work is to gather the whole requisite data to the modelization stage based on the extrapolation of a mathematical tool, type population evaluation with a double object to supply the basis information useful for the model, and to establish an experimental data base for the model validation. 9 refs., 4 figs

Nasal packing with ventilated nasal packs; a comparison with traditional vaseline nasal pack

International Nuclear Information System (INIS)

Alam, J.; Siddiqui, M.W.; Abbas, A.; Sami, M.; Ayub, Z.

2017-01-01

To compare the benefits of ventilated nasal packing with traditional vaseline guaze nasal packing. Study Design: Randomized controlled trial. Place and Duration of Study: This study was conducted at CMH Multan, from Jun 2014 to Dec 2014. Material and Methods: In this study, sample size of 80 patients was calculated using WHO calculator. Patients were divided in two groups using lottery method endotracheal tube and piece of surgical glove filled with ribbon guaze was utilized for fabricated ventilated nasal pack and compared with traditional nasal packs. Nasal obstruction and sleep disturbance were studied at eight hours and twenty-four hours following surgery using visual analog scale. Results: Mean nasal obstruction with ventilated nasal pack was 45.62 +- 6.17 and with Vaseline nasal pack was 77.67 +- 4.85 which was statistically significant (p=0.001) in both the groups. Mean sleep disturbance in both the groups was 46.32 +- 5.23 and 68.75 +- 2.70 respectively which was statistically significant (p=0.001) in both the groups. Conclusion: Patients with ventilated nasal packs were found to have better tolerance to nasal packs due to less nasal obstruction and sleep disturbance

Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications

Science.gov (United States)

Preti, Raffaella

2016-01-01

The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large amount of samples must be analyzed fast using reliable and solvent-saving apparatus. The literature hereby described shows how the outstanding performances provided by core-shell particles column on a traditional HPLC instruments are comparable to those obtained with a costly UHPLC instrumentation, making this novel column a promising key tool in food analysis. PMID:27143972

Humic colloid-borne migration of uranium in sand columns

International Nuclear Information System (INIS)

Artinger, R.; Rabung, T.; Kim, J.I.; Sachs, S.; Schmeide, K.; Heise, K.H.; Bernhard, G.; Nitsche, H.

2002-09-01

Column experiments were carried out to investigate the influence of humic colloids on subsurface uranium migration. The columns were packed with well-characterized aeolian quartz sand and equilibrated with groundwater rich in humic colloids (dissolved organic carbon (DOC): 30 mg dm -3 ). U migration was studied under an Ar/1% CO 2 gas atmosphere as a function of the migration time, which was controlled by the flow velocity or the column length. In addition, the contact time of U with groundwater prior to introduction into a column was varied. U(VI) was found to be the dominant oxidation state in the spiked groundwater. The breakthrough curves indicate that U was transported as a humic colloid-borne species with a velocity up to 5% faster than the mean groundwater flow. The fraction of humic colloid-borne species increases with increasing prior contact time and also with decreasing migration time. The migration behavior was attributed to a kinetically controlled association/dissociation of U onto and from humic colloids and also a subsequent sorption of U onto the sediment surface. The column experiments provide an insight into humic colloid-mediated U migration in subsurface aquifers

Deuterium exchange reaction between hydrogen and water in a trickle-bed column packed with novel catalysts

International Nuclear Information System (INIS)

Ahn, D. H.; Baek, S. W.; Lee, H. S.; Kim, K. R.; Kang, H. S.; Lee, S. H.; Jeong, H. S.

1998-01-01

The activity of a novel catalyst (Pt/SDBC) for deuterium exchange reaction between water and hydrogen streams in a trickle bed was measured. The performance of the catalyst was compared with a commercial catalyst with same metal content. The catalytic activity for the bed of wet-proofed catalyst diluted with hydrophillic packing material also measured. The Pt/SDBC catalyst shows higher activity in the liquid phase reaction than the commercial catalyst as measured in the vapor phase reaction. The performance for 50% dilution of the Pt/SDBC catalyst bed with hydrophillic packing material is better than that of the 100% bed due to more liquid holdup and better water distribution

Hydrodynamic Study Of Column Bioleaching Processes

Directory of Open Access Journals (Sweden)

Sadowski Zygmunt

2015-06-01

Full Text Available The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore with the support, inertial materials (glass small balls and polyethylene beads was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.

Experimental Study on Pressure Drop and Flow Dispersion in Packed Bed of Natural Zeolite

Directory of Open Access Journals (Sweden)

Ruya Petric Marc

2018-01-01

Full Text Available The use of conventional correlation for pressure drop and dispersion coefficient calculation may result in inaccurate values for zeolite packed bed as the correlations are generally developed for regularly shaped and uniformly sized particles. To support the research on the application of modified natural zeolite as tar cracking catalyst, the research on the hydrodynamic behaviour of zeolite packed bed has been conducted. Experiments were carried out using a glass column with diameter of 37.8 mm. Natural zeolite with particle size of about 2.91 to 6.4 mm was applied as packing material in the column, and the bed height was varied at 9, 19 and 29 cm. Air was used as the fluid that flows through the bed and nitrogen was used as a tracer for residence time distribution determination. Air flow rates were in the range of 20 to 100 mL/s which correspond to the laminar-transitional flow regime. The pressure drops through the bed were in the range of 1.7 to 95.6 Pa, depending on the air flow rate and bed height. From these values, the parameters in the Ergun equation were estimated, taking into account the contribution by wall effect when the ratio of column to particle diameter is low. The viscous and inertial term constants in the Ergun equation calculated ranges from 179 to 199 and 1.41 to 1.47 respectively while the particle sphericity ranges from 0.56 to 0.59. The reactor Peclet number were determined to range from 5.2 to 5.5, which indicated significant deviation from a plug flow condition.

Electrical Capacitance Volume Tomography for the Packed Bed Reactor ISS Flight Experiment

Science.gov (United States)

Marashdeh, Qussai; Motil, Brian; Wang, Aining; Liang-Shih, Fan

2013-01-01

Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and

Mass transfer models analysis for the structured packings; Analisis de los modelos en transferencia de masa para los empaques estructurados

Energy Technology Data Exchange (ETDEWEB)

Suastegui R, A O

1997-12-01

The models that have been developing, to understand the mechanism of the mass transfer through the structured packings, present limitations for their application, existing then uncertainty in order to use them in the chemical industrial processes. In this study the main parameters used in the mass transfer are: the hydrodynamic of the bed of the column, the geometry of the bed, physical-chemical properties of the mixture and the flow regime of the operation between the flows liquid-gas. The sensibility of each one of these parameters generate an arduous work to develop right proposals and good interpretation of the phenomenon. With the purpose of showing the importance of these parameters mentioned in the mass transfer, this work is analyzed the process of absorption for the system water-air, using the models to the structured packings in packed columns. The models selected were developed by Bravo and collaborators in 1985 and 1992, in order to determine the parameters previous mentioned for the system water-air, using a structured packing built in the National Institute of Nuclear Research. In this work is showed the results of the models application and their discussion. (Author).

Study and selection of structured packing material: metallic, polymeric or ceramic to operate a column of absorption polluting gases coming from brick kilns efficiently

International Nuclear Information System (INIS)

Salazar P, A.

2012-01-01

In this research three structured packing materials were characterized: a metallic, polymeric and ceramic. The study of the physical properties of structured packing materials, and their behavior within the absorption column allowed to suggest a gas-liquid contactor material with higher mechanical and chemical resistance, which is more efficient for the treatment of sour gases from brick kilns. To study the mechanical properties (hardness, tension and elastic modulus) were used procedures of the American Society for Testing Materials, as well as resistance to corrosion. The geometric characteristics, the density, the melting temperature and the weight were tested with procedures of the measuring equipment. The structure was evaluated by X-ray diffraction, morphology was observed by scanning electron microscopy coupled to a sound of dispersive energy of X-ray, to quantify elemental chemical composition. The interaction of gas-liquid contactors materials in presence of CO 2 , was evaluated in three absorption columns built of Pyrex glass, with a diameter of 0.1016 m, of 1.5 m in height, 0.0081m 2 cross-sectional area, packed with every kind of material: metallic, polymeric and ceramic, processing a gas flow of 20m 3 / h at 9% CO 2 , in air and a liquid flow to 30% of Mea 5 L/min. The results of the properties studied were by the metallic material: more density, higher roughness, the greater tensile strength, greater resistance to corrosion in the presence of an aqueous solution of monoethanolamine (Mea) to 30% by weight, improvement more efficient absorption of CO 2 , and higher modulus of elasticity. The polymeric material was characterized to have lower hardness, lower roughness, lower density, lower melting temperature, greater resistance to corrosion in the presence of 1 N H 2 SO 4 aqueous solution, and allowed an absorption efficiency of CO 2 , 2% lower than that presented by the material metallic. The ceramic material found to be the hardest of the three

Analysis of an industrial process simulator column using third-generation computed tomography

International Nuclear Information System (INIS)

Kirita, Rodrigo; Carvalho, Diego Vergacas de Sousa; Mesquita, Carlos Henrique de; Vasquez, Pablo Antonio S.; Hamada, Margarida Mizue

2011-01-01

The CT methodology must be tested using a simulator column in the laboratory before applying it in the industrial plants. In this work, using the third-generation industrial computed tomography developed at the IPEN, a gas absorption column, used as a simulator column for industrial process was evaluated. It is a glass cylindrical tube of 90 mm diameter and 1400 mm height constituted the following parts: random packed column, liquid circuit (water), gas circuit and analysis was used as a simulator column. Gamma ray tomography experiments were carried out, using this simulator column empty and filled with water. In this work the scanner was setting for 90 views and 19 projections for each detector totalizing 11970 projections. The resulting images describe the presence of liquid or gas phases and are possible to evaluate the linear attenuation coefficients inside the column. In this case, linear attenuation coefficient for water was 0.0813 cm-1. It was established that the newly developed third-generation fan-beam arrangement gamma scanner unit has a good spatial resolution acceptable given the size of the column used in this study. (author)

To Pack or Not to Pack? A Randomized Trial of Vaginal Packing After Vaginal Reconstructive Surgery.

Science.gov (United States)

Westermann, Lauren B; Crisp, Catrina C; Oakley, Susan H; Mazloomdoost, Donna; Kleeman, Steven D; Benbouajili, Janine M; Ghodsi, Vivian; Pauls, Rachel N

2016-01-01

Placement of vaginal packing after pelvic reconstructive surgery is common; however, little evidence exists to support the practice. Furthermore, patients have reported discomfort from the packs. We describe pain and satisfaction in women treated with and without vaginal packing. This institutional review board-approved randomized-controlled trial enrolled patients undergoing vaginal hysterectomy with prolapse repairs. The primary outcome was visual analog scales (VASs) for pain on postoperative day 1. Allocation to "packing" ("P") or "no-packing" ("NP") arms occurred intraoperatively at the end of surgery. Visual analog scales regarding pain and satisfaction were completed early on postoperative day 1 before packing removal. Visual analog scale scores for pain, satisfaction, and bother attributable to packing were recorded before discharge. All packing and perineal pads were weighed to calculate a "postoperative vaginal blood loss." Perioperative data were collected from the hospital record. Our sample size estimation required 74 subjects. Ninety-three women were enrolled. After exclusions, 77 were randomized (P, 37; NP, 40). No differences were found in surgical information, hemoglobin levels, or narcotic use between groups. However, "postoperative vaginal blood loss" was greater in packed subjects (P discharge (P, 35.0 vs NP, 40.0; P = 0.43] were not significantly different between treatment arms. Likewise, VAS scores for satisfaction before removal of packing (P, 81.0 vs NP, 90.0; P = 0.08] and before discharge (P, 90.0 vs NP, 90.5; P = 0.60] were not significantly different. Packed patients noted lower nursing verbal pain scores (P = 0.04) and used less ketorolac (P = 0.01). Bother from packing was low overall. Although there was no difference based on VAS, women receiving vaginal packing had lower nursing documented pain and used less ketorolac than packed women. Vaginal packing may provide benefit and can remain part of the surgical practice.

Methacrylate-bonded covalent-organic framework monolithic columns for high performance liquid chromatography.

Science.gov (United States)

Liu, Li-Hua; Yang, Cheng-Xiong; Yan, Xiu-Ping

2017-01-06

Covalent-organic frameworks (COFs) are a newfangled class of intriguing microporous materials. Considering their unique properties, COFs should be promising as packing materials for high performance liquid chromatography (HPLC). However, the irregular shape and sub-micrometer size of COFs synthesized via the traditional methods render the main obstacles for the application of COFs in HPLC. Herein, we report the preparation of methacrylate-bonded COF monolithic columns for HPLC to overcome the above obstacles. The prepared COF bonded monolithic columns not only show good homogeneity and permeability, but also give high column efficiency, good resolution and precision for HPLC separation of small molecules including polycyclic aromatic hydrocarbons, phenols, anilines, nonsteroidal anti-inflammatory drugs and benzothiophenes. Compared with the bare polymer monolithic column, the COF bonded monolithic columns show enhanced hydrophobic, π-π and hydrogen bond interactions in reverse phase HPLC. The results reveal the great potential of COF bonded monoliths for HPLC and COFs in separation sciences. Copyright © 2016 Elsevier B.V. All rights reserved.

Accurate measurements of infinite dilution activity coefficients using gas chromatography with static-wall-coated open-tubular columns.

Science.gov (United States)

Xu, Qianqian; Su, Baogen; Luo, Xinyi; Xing, Huabin; Bao, Zongbi; Yang, Qiwei; Yang, Yiwen; Ren, Qilong

2012-11-06

Wall-coated open-tubular (WCOT) columns provide higher column efficiency and lower solute interfacial adsorption effect than packed columns. However, previous efforts used to measure the infinite dilution activity coefficient (γ(∞)) via a chromatographic technique have used packed columns, because the low carrier gas flow rate (U) and the small stationary phase amount (n(2)) in WCOT columns raise large errors. By rationally revising the γ(∞)-calculation equation for static-wall-coated open-tubular column, we observed that U and n(2) are not necessarily needed and the resulting error could be reduced, and WCOT column gas chromatography subsequently became a superior method for the accurate γ(∞) determination. In this study, we validate our revised γ(∞)-calculation equation by measuring γ(∞) in an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate system, in which 55 organic compounds covering a wide range of functional groups were used as probe solutes and their γ(∞) values in the ionic liquid were determined at 40.0, 50.0, and 60.0 °C. Experimental error analysis shows that our revised equation remarkably reduces the error compared to the common γ(∞)-calculation equation. Our data is consistent with previously reported values obtained via other techniques, which further proves the credibility of our revised equation. The accurately determined γ(∞) values can be directly used to calculate the partial molar excess enthalpy, selectivity, and capacity, which will benefit for the rapid screening of solvents (especially ionic liquids) in separation approaches.

Mini-column assay for rapid detection of malachite green in fish.

Science.gov (United States)

Shalaby, Ali R; Emam, Wafaa H; Anwar, Mervat M

2017-07-01

A simple, rapid and economical mini-column method for detecting malachite green (MG) residue in fish was developed. The method used a column with 2mm ID that was tightly packed with silica gel followed by alumina. Detection of MG was performed by viewing the developed mini-column at visible light by naked eye; where MG was seen as compact green band at the confluence of the silica gel layer with alumina layer. The limit of detection of the assay was 2ng which conform the minimum required performance limit (MRPL). Evaluation utility of the method indicated that all blank and spiked samples at levels below MRPL were assessed as accepted. The intensity of the green band increased whenever MG level in the extract increased; indicated that suggested mini-column technique could be used for semi-quantitative determination of MG in fish samples. The method can be used to select the questionable samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sorption of nitrate onto amine-crosslinked wheat straw: characteristics, column sorption and desorption properties.

Science.gov (United States)

Xing, Xu; Gao, Bao-Yu; Zhong, Qian-Qian; Yue, Qin-Yan; Li, Qian

2011-02-15

The nitrate removal process was evaluated using a fixed-bed column packed with amine-crosslinked wheat straw (AC-WS). Column sorption and desorption characteristics of nitrate were studied extensively. Solid-state (13)C NMR and zeta potential analysis validated the existence of crosslinked amine groups in AC-WS. Raman shift of the nitrate peaks suggested the electrostatic attraction between the adsorbed ions and positively charged amine sites. The column sorption capacity (q(ed)) of the AC-WS for nitrate was 87.27 mg g(-1) in comparison with the raw WS of 0.57 mg g(-1). Nitrate sorption in column was affected by bed height, influent nitrate concentration, flow rate and pH, and of all these, influent pH demonstrated an essential effect on the performance of the column. In addition, desorption and dynamic elution tests were repeated for several cycles, with high desorption rate and slight losses in its initial column sorption capacity. Copyright © 2010 Elsevier B.V. All rights reserved.

Modelling and dynamics of an air separation rectification column as part of an IGCC power plant

Energy Technology Data Exchange (ETDEWEB)

Seliger, B.; Hanke-Rauschenbach, R.; Hannemann, F.; Sundmacher, K. [Otto Von Guericke University, Magdeburg (Germany)

2006-04-15

An Integrated Gasification Combined Cycle plant (IGCC) opens the well-proven and highly efficient combined cycle process to fossil fuels, like coal or heavy refinery residues. Such a plant thereby possesses a novel linkage of typical energy engineering related units, e.g. a gas turbine and typical process engineering parts, which in the present case is an air separation plant. Different responses from the connected components can cause undesired mass flow fluctuations within the system especially during changing load demands. The cryogenic rectification column, as the core of the air separation plant, strongly affects the system's transient behaviour. The upper part of such a heat-integrated double column, a packed column with structured packing, has therefore been more closely investigated in the present paper. For this purpose, a dynamic model of such a column has been developed which is also able to describe the pressure dynamics supposedly responsible for these mass flow fluctuations. The transient behaviour of the uncontrolled column is analysed and discussed with special regard to pressure dynamics. The column pressure responds to disturbances on two different time scales. The short-term response, which is in the range of 100-200 s, is governed by the transient behaviour of the fluid dynamics and is discussed in detail. The long-term response is dominated by the nonlinear dynamics of the concentration profiles. The time constant of this response depends strongly on the direction and intensity of the disturbance and takes from 10,000 up to several 100,000 s.

Phenol Biodegradation by Free and Immobilized Candida tropicalis RETL-Crl on Coconut Husk and Loofah Packed in Biofilter Column

International Nuclear Information System (INIS)

Shazryenna, D; Ruzanna, R; Jessica, M S; Piakong, M T

2015-01-01

Phenols and its derivatives are environmental pollutant commonly found in many industrial effluents. It is toxic in nature and causes various health hazards. However, they are poorly removed in conventional biological processes due to their toxicity. Immobilization of microbial cells has received increasing interest in the field of waste treatment and creates opportunities in a wide range of sectors including environmental pollution control. Live cells of phenol-degrading yeast, Candida tropicalis RETL-Crl, were immobilized on coconut husk and loofah by adsorption. The immobolized particle was packed into biofilter column which used for continuous treatment of a phenol with initial phenol concentration of 3mM. Both loofah and coconut husk have similar phenol biodegradation rate of 0.0188 gL −1 h −1 within 15 hours to achieve a phenol removal efficiency of 100%. However loofah have lower biomass concentration of 4.22 gL −1 compared to biomass concentration on coconut husk, 4.39 gL −1 . Coconut husk contain higher biomass concentration which makes it better support material than loofah. Fibrous matrices such as loofah and coconut husk provide adequate supporting surfaces for cell adsorption, due to their high specific surface area. Therefore, coconut husk and loofah being an agricultural waste product have the potential to be used as low-cost adsorbent and support matrix for microbial culture immobilization for the removal of organic pollutant from wastewater. (paper)

Dry-column chromatography of uranium. Application to chemical analysis of monazite and phosphate rock for uranium

Energy Technology Data Exchange (ETDEWEB)

Oguma, K; Kuroda, R [Chiba Univ. (Japan). Faculty of Engineering

1981-08-01

A dry-column chromatographic technique has been applied to the separation of uranium from complicated matrices. It has been demonstrated that operating parameters of thin-layer chromatography on silanized silica gel in isopropyl ether - tetrahydrofuran - nitric acid (65:20:3) can be transferred to this technique. Chromatograms are thus easily developed on dry packed column with the solvent system of the type used in the TLC. Uranium is eluted off the column and determined with Arsenazo III spectrophotometrically. The technique is successfully applied to the determination of uranium in monazite and phosphate rock samples with good precision and accuracy.

Single-column ion chromatography with determination of hydrazoic acid produced in spent nuclear fuel reprocessing

International Nuclear Information System (INIS)

Ma Guilan; Tan Shuping

2006-01-01

The reaction of hydrazine and its derivative with ammonium metavanadate may produce hydrazoic acid (HN 3 ). A single-column ion chromatography is used for the determination of HN 3 after neutralizing the rest acid in the sample with sodium hydroxide. Chromatography separation of HN 3 is carried out on a 25 cm x 0.46 cm (inside diameter) stainless steel column packed with Vydac IC302 ion Chromatography packing. The eluent is 1 mmol/L o-phthalic acid, and the ion is detected by conductivity detector. The detection limit in the presence chromatography is 5 μg/mL, the linear range is from 5 to 201 μg/mL, the linear correlation coefficient is 0.9994, respectively. The analysis accuracy is 2% for standard sample, and the detection limit is 51 μg/mL for HN 3 in the real sample. (authors)

Pre-treatment of pyridine wastewater by new cathodic-anodic-electrolysis packing.

Science.gov (United States)

Jin, Yang; Yue, Qinyan; Yang, Kunlun; Wu, Suqing; Li, Shengjie; Gao, Baoyu; Gao, Yuan

2018-01-01

A novel cathodic-anodic-electrolysis packing (CAEP) used in the treatment of pyridine wastewater was researched, which mainly consisted of 4,4'-diamino-2,2'-disulfonic acid (DSD acid) industrial iron sludge. The physical properties and morphology of the packing were studied. The CAEP was used in a column reactor during the pretreatment of pyridine wastewater. The influence of pH, hydraulic retention time (HRT), the air-liquid ratio (A/L) and the initial concentration of pyridine were investigated by measuring the removal of total organic carbon (TOC) and pyridine. The characterization results showed that the bulk density, grain density, water absorption percentage and specific surface area were 921kg/m 3 , 1086kg/m 3 , 25% and 29.89m 2 /g, respectively; the removal of TOC and pyridine could reach 50% and 58% at the optimal experimental conditions (pH=3, HRT=8hr, A/L=2). Notably, the surface of the packing was renewed constantly during the running of the filter, and the handling capacity was stable after running for three months. Copyright © 2017. Published by Elsevier B.V.

Mass transfer between a fluid and an immersed object in liquid–solid packed and fluidized beds

Directory of Open Access Journals (Sweden)

NEVENKA BOSKOVIC-VRAGOLOVIC

2005-11-01

Full Text Available Themass transfer coefficient between fluid and an immersed sphere in liquid packed and fluidized beds of inert spherical particles have been studied experimentally using a column 40 mm in diameter. The mass transfer data were obtained by studying the transfer of benzoic acid from the immersed sphere to flowing water using the dissolution method. In all runs, the mass transfer rates were determined in the presence of inert glass particles 0.50-2.98 mm in diameter. The influence of different parameters, such as: liquid velocity, particles size and bed voidage, on the mass transfer in packed and fluidized beds is presented. The obtained experimental data for mass transfer in the packed and particulate fluidized bed were correlated by a single correlation, thus confirming the similarity between the two systems.

The Dynamic Behavior of Water Flowing Through Packed Bed of Different Particle Shapes and Sizes

Directory of Open Access Journals (Sweden)

Haneen Ahmed Jasim

2017-12-01

Full Text Available An experimental study was conducted on pressure drop of water flow through vertical cylindrical packed beds in turbulent region and the influence of the operating parameters on its behavior. The bed packing was made of spherical and non-spherical particles (spheres, Rasching rings and intalox saddle with aspect ratio range 3.46 D/dp 8.486 obtaining bed porosities 0.396 0.84 and Reynolds number 1217 21758. The system is consisted of 5 cm inside diameter Perspex column, 50 cm long; distilled water was pumped through the bed with flow rate 875, 1000, 1125, 1250,1375 and 1500 l/h and inlet water temperature 20, 30, 40 and 50 ˚C. The packed bed system was monitored by using LabVIEW program, were the results have been obtained from Data Acquisition Adaptor (DAQ.

Experimental investigation of virus and clay particles cotransport in partially saturated columns packed with glass beads.

Science.gov (United States)

Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

2015-02-15

Suspended clay particles in groundwater can play a significant role as carriers of viruses, because, depending on the physicochemical conditions, clay particles may facilitate or hinder the mobility of viruses. This experimental study examines the effects of clay colloids on the transport of viruses in variably saturated porous media. All cotransport experiments were conducted in both saturated and partially saturated columns packed with glass beads, using bacteriophages MS2 and ΦX174 as model viruses, and kaolinite (KGa-1b) and montmorillonite (STx-1b) as model clay colloids. The various experimental collision efficiencies were determined using the classical colloid filtration theory. The experimental data indicated that the mass recovery of viruses and clay colloids decreased as the water saturation decreased. Temporal moments of the various breakthrough concentrations collected, suggested that the presence of clays significantly influenced virus transport and irreversible deposition onto glass beads. The mass recovery of both viruses, based on total effluent virus concentrations, was shown to reduce in the presence of suspended clay particles. Furthermore, the transport of suspended virus and clay-virus particles was retarded, compared to the conservative tracer. Under unsaturated conditions both clay particles facilitated the transport of ΦX174, while hindered the transport of MS2. Moreover, the surface properties of viruses, clays and glass beads were employed for the construction of classical DLVO and capillary potential energy profiles, and the results suggested that capillary forces play a significant role on colloid retention. It was estimated that the capillary potential energy of MS2 is lower than that of ΦX174, and the capillary potential energy of KGa-1b is lower than that of STx-1b, assuming that the protrusion distance through the water film is the same for each pair of particles. Moreover, the capillary potential energy is several orders of

Long-term operational studies of lab-scale pumice-woodchip packed stormwater biofilters.

Science.gov (United States)

Cheng, Jing; Yuan, Qingke; Kim, Youngchul

2017-06-13

The performance of three pumice-woodchip packed stormwater biofilter (PWSWBF) systems with three packing volume ratios of pumice to woodchip (1:2, 1:1 and 2:1) were compared. The results show that the PWSWBF system packed with a lower percentage of woodchip attained a higher removal efficiency of TCOD, TN, NH 4 -N and TP, whereas all three systems completely removed nitrate. The highest removal efficiencies for TCOD, TN, NH 4 -N, NO 3 -N and TP were 95%, 70%, 86%, 100% and 100%, respectively. In the biofilter with a lower percentage of woodchip, the pollutants that get removed through aerobic biological processes were removed more significantly, which is attributed to less oxygen depletion via woodchip decomposition, which is common under wet conditions. Nitrate was significantly removed via denitrification in all three systems, indicating that the woodchip that occupied one-third of the main media was sufficient for denitrification, and also that the oxygen condition inside the column was proper for denitrification to proceed. A smaller amount of woodchip as the packing material also mitigated the adverse effect of the release of organics from the media during the initial period. In addition, the system showed very good buffering capacity, in that the outflow pH was constant within the optimal range for microorganism growth.

Evaluation of polymeric materials packed in fixed bed column for oil water remediation; Avaliacao de materiais polimericos empacotados em colunas de leito fixo para a remediacao de aguas oleosas

Energy Technology Data Exchange (ETDEWEB)

Queiros, Yure G.C.; Barros, Cintia Chagas; Oliveira, Roberta S.; Marques, Luiz R.S.; Cunha, Luciana; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas Eloisa Mano], e-mail: yuregomes@ima.ufrj.br, e-mail: elucas@ima.ufrj.br

2007-07-01

Polymeric resins are being tried as an alternative material for treating oily waters from the petroleum industry, which have already been treated by conventional methods. The objective of this work has been to evaluate the purification degree of synthetic oily waters when treated in fixed bed columns packed with polymeric resins made up of hydrophilic and lipophilic moieties. The analysis used for characterizing the total grease and oil content (TOG) was fluorimetry. Starting oily waters of average TOG 50 ppm were prepared. Data obtained from eluted waters did not outweigh 10% of the TOG values of starting solutions in some blends of resins with a pretty good mechanical stability under the increase of pressure. Organoclay material showed a good retention performance, but has presented a mechanical instability too, compromising its use for larger amounts of wastewater. (author)

Temperature-based on-column solute focusing in capillary liquid chromatography reduces peak broadening from pre-column dispersion and volume overload when used alone or with solvent-based focusing.

Science.gov (United States)

Groskreutz, Stephen R; Horner, Anthony R; Weber, Stephen G

2015-07-31

On-column focusing is essential for satisfactory performance using capillary scale columns. On-column focusing results from generating transient conditions at the head of the column that lead to high solute retention. Solvent-based on-column focusing is a well-known approach to achieve this. Temperature-assisted on-column focusing (TASF) can also be effective. TASF improves focusing by cooling a short segment of the column inlet to a temperature that is lower than the column temperature during the injection and then rapidly heating the focusing segment to the match the column temperature. A troublesome feature of an earlier implementation of TASF was the need to leave the capillary column unpacked in that portion of the column inside the fitting connecting it to the injection valve. We have overcome that problem in this work by packing the head of the column with solid silica spheres. In addition, technical improvements to the TASF instrumentation include: selection of a more powerful thermo-electric cooler to create faster temperature changes and electronic control for easy incorporation into conventional capillary instruments. Used in conjunction with solvent-based focusing and with isocratic elution, volumes of paraben samples (esters of p-hydroxybenzoic acid) up to 4.5-times the column liquid volume can be injected without significant bandspreading due to volume overload. Interestingly, the shapes of the peaks from the lowest volume injections that we can make, 30nL, are improved when using TASF. TASF is very effective at reducing the detrimental effects of pre-column dispersion using isocratic elution. Finally, we show that TASF can be used to focus the neuropeptide galanin in a sample solvent with elution strength stronger than the mobile phase. Here, the stronger solvent is necessitated by the need to prevent peptide adsorption prior to and during analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Capillary trap column with strong cation-exchange monolith for automated shotgun proteome analysis.

Science.gov (United States)

Wang, Fangjun; Dong, Jing; Jiang, Xiaogang; Ye, Mingliang; Zou, Hanfa

2007-09-01

A 150 microm internal diameter capillary monolithic column with a strong cation-exchange stationary phase was prepared by direct in situ polymerization of ethylene glycol methacrylate phosphate and bisacrylamide in a trinary porogenic solvent consisting dimethylsulfoxide, dodecanol, and N,N'-dimethylformamide. This phosphate monolithic column exhibits higher dynamic binding capacity, faster kinetic adsorption of peptides, and more than 10 times higher permeability than the column packed with commercially available strong cation-exchange particles. It was applied as a trap column in a nanoflow liquid chromatography-tandem mass spectrometry system for automated sample injection and online multidimensional separation. It was observed that the sample could be loaded at a flow rate as high as 40 microL/min with a back pressure of approximately 1300 psi and without compromising the separation efficiency. Because of its good orthogonality to the reversed phase separation mechanism, the phosphate monolithic trap column was coupled with a reversed-phase column for online multidimensional separation of 19 microg of the tryptic digest of yeast proteins. A total of 1522 distinct proteins were identified from 5608 unique peptides (total of 54,780 peptides) at the false positive rate only 0.46%.

Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications

OpenAIRE

Preti, Raffaella

2016-01-01

The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large am...

Hemifield columns co-opt ocular dominance column structure in human achiasma.

Science.gov (United States)

Olman, Cheryl A; Bao, Pinglei; Engel, Stephen A; Grant, Andrea N; Purington, Chris; Qiu, Cheng; Schallmo, Michael-Paul; Tjan, Bosco S

2018-01-01

In the absence of an optic chiasm, visual input to the right eye is represented in primary visual cortex (V1) in the right hemisphere, while visual input to the left eye activates V1 in the left hemisphere. Retinotopic mapping In V1 reveals that in each hemisphere left and right visual hemifield representations are overlaid (Hoffmann et al., 2012). To explain how overlapping hemifield representations in V1 do not impair vision, we tested the hypothesis that visual projections from nasal and temporal retina create interdigitated left and right visual hemifield representations in V1, similar to the ocular dominance columns observed in neurotypical subjects (Victor et al., 2000). We used high-resolution fMRI at 7T to measure the spatial distribution of responses to left- and right-hemifield stimulation in one achiasmic subject. T 2 -weighted 2D Spin Echo images were acquired at 0.8mm isotropic resolution. The left eye was occluded. To the right eye, a presentation of flickering checkerboards alternated between the left and right visual fields in a blocked stimulus design. The participant performed a demanding orientation-discrimination task at fixation. A general linear model was used to estimate the preference of voxels in V1 to left- and right-hemifield stimulation. The spatial distribution of voxels with significant preference for each hemifield showed interdigitated clusters which densely packed V1 in the right hemisphere. The spatial distribution of hemifield-preference voxels in the achiasmic subject was stable between two days of testing and comparable in scale to that of human ocular dominance columns. These results are the first in vivo evidence showing that visual hemifield representations interdigitate in achiasmic V1 following a similar developmental course to that of ocular dominance columns in V1 with intact optic chiasm. Copyright © 2017 Elsevier Inc. All rights reserved.

Studies about the transfer phenomena of tritium from liquid to gaseous phase in a catalyst and ordered packing successive system

International Nuclear Information System (INIS)

Bornea, Anisia; Cristescu, Ion; Zamfirache, Marius; Varlam, Carmen

2002-01-01

The processes for hydrogen isotope separation are very important for nuclear technology. One of the most important processes for tritium separation, is the catalyst isotope exchange water-hydrogen. In a column of isotope exchange tritium is transferred from liquid phase (tritiated heavy water) in gaseous phase (hydrogen). In the experimental setup, which was used, the column of catalytic isotope exchange is filled with successive layers of catalyst and ordered packing. The catalyst consists of 95.5 wt.% of PTFE, 4.1 wt. % of carbon and 0.40 wt. % of platinum and was made of Raschig rings 10 x 10 x 2 mm. The ordered packing was of B7 type and consists of a phosphor bronze wire mesh of 0.18 x 0.48 mm dimension. We analysed the transfer phenomena of tritium from liquid to gaseous phase, in this system. The mathematical model presented in the paper allowed computing experimental data for testing the catalyst performances. In this way the speed constants which characterized the isotopic exchange on the catalysis bed ks, and the distillation on the ordered packing kd, were expressed as function of experimental concentrations and hydrodynamic conditions. (authors)

Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

Science.gov (United States)

Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

2016-06-01

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

A novel bench-scale column assay to investigate site-specific nitrification biokinetics in biological rapid sand filters

DEFF Research Database (Denmark)

Tatari, Karolina; Smets, Barth F.; Albrechtsen, Hans-Jørgen

2013-01-01

A bench-scale assay was developed to obtain site-specific nitrification biokinetic information from biological rapid sand filters employed in groundwater treatment. The experimental set-up uses granular material subsampled from a full-scale filter, packed in a column, and operated with controlled...

Characterising gas behaviour during gas-liquid co-current up-flow in packed beds using magnetic resonance imaging

OpenAIRE

Collins, James HP; Sederman, Andrew John; Gladden, Lynn Faith; Afeworki, Mobae; Kushnerick, J Douglas; Thomann, Hans

2016-01-01

Magnetic resonance (MR) imaging techniques have been used to study gas phase dynamics during co-current up-flow in a column of inner diameter 43 mm, packed with spherical non-porous elements of diameters of 1.8, 3 and 5 mm. MR measurements of gas hold-up, bubble-size distribution, and bubble-rise velocities were made as a function of flow rate and packing size. Gas and liquid flow rates were studied in the range of 20–250 cm3 s−1 and 0–200 cm3 min−1, respectively. The gas hold-up within the b...

A Reconciliation of Packed Column Permeability Data: Column Permeability as a Function of Particle Porosity

Directory of Open Access Journals (Sweden)

Hubert M. Quinn

2014-01-01

Full Text Available In his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.

Measurement of liquid mixing characteristics in large-sized ion exchange column for isotope separation by stepwise response method

International Nuclear Information System (INIS)

Fujine, Sachio; Saito, Keiichiro; Iwamoto, Kazumi; Itoi, Toshiaki.

1981-07-01

Liquid mixing in a large-sized ion exchange column for isotope separation was measured by the step-wise response method, using NaCl solution as tracer. A 50 cm diameter column was packed with an ion exchange resin of 200 μm in mean diameter. Experiments were carried out for several types of distributor and collector, which were attached to each end of the column. The smallest mixing was observed for the perforated plate type of the collector, coupled with a minimum stagnant volume above the ion exchange resin bed. The 50 cm diameter column exhibited the better characteristics of liquid mixing than the 2 cm diameter column for which the good performance of lithium isotope separation had already been confirmed. These results indicate that a large increment of throughput is attainable by the scale-up of column diameter with the same performance of isotope separation as for the 2 cm diameter column. (author)

The performance of a trickle-bed reactor packed with a Pt/SDBC catalyst mixture for the CECE process

International Nuclear Information System (INIS)

Paek, Seungwoo; Ahn, Do-Hee; Choi, Heui-Joo; Kim, Kwang-Rag; Lee, Minsoo; Yim, Sung-Paal; Chung, Hongsuk; Song, Kyu-Min; Sohn, Soon Hwan

2007-01-01

The combined electrolysis and catalytic exchange (CECE) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy wastewater streams because of its high separation factor and mild operating conditions. A hydrophobic platinum/styrene-divinyl benzene copolymer (Pt/SDBC) catalyst which was developed for the liquid-phase catalytic exchange (LPCE) column of the Wolsong tritium removal facility (WTRF) has been tested in a trickle bed reactor for the design of the CECE process. An experimental apparatus has been built for the testing of the catalyst at various temperatures and gas velocities. The catalyst column was packed with a mixture of a hydrophobic catalyst and a hydrophilic packing (Dixon gauze ring) to improve the liquid distribution and vapor/liquid transfer area. Many tests have been carried out at Korea Atomic Energy Research Institute (KAERI) to measure the activity of the catalyst, K y a (1 s -1 ), under various operating conditions. K y a increases with the hydrogen flow rates in the range of 0.4-1.6 m s -1 at STP. The height of the catalyst column was determined from these K y a values according to the reaction temperatures and hydrogen flow rates

The performance of a trickle-bed reactor packed with a Pt/SDBC catalyst mixture for the CECE process

Energy Technology Data Exchange (ETDEWEB)

Paek, Seungwoo [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)], E-mail: swpaek@kaeri.re.kr; Ahn, Do-Hee; Choi, Heui-Joo; Kim, Kwang-Rag; Lee, Minsoo; Yim, Sung-Paal; Chung, Hongsuk [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Song, Kyu-Min; Sohn, Soon Hwan [Korea Electric Power Research Institute, 103-16 Munji-dong, Yuseong-gu, Daejeon 305-380 (Korea, Republic of)

2007-10-15

The combined electrolysis and catalytic exchange (CECE) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy wastewater streams because of its high separation factor and mild operating conditions. A hydrophobic platinum/styrene-divinyl benzene copolymer (Pt/SDBC) catalyst which was developed for the liquid-phase catalytic exchange (LPCE) column of the Wolsong tritium removal facility (WTRF) has been tested in a trickle bed reactor for the design of the CECE process. An experimental apparatus has been built for the testing of the catalyst at various temperatures and gas velocities. The catalyst column was packed with a mixture of a hydrophobic catalyst and a hydrophilic packing (Dixon gauze ring) to improve the liquid distribution and vapor/liquid transfer area. Many tests have been carried out at Korea Atomic Energy Research Institute (KAERI) to measure the activity of the catalyst, K{sub y}a (1 s{sup -1}), under various operating conditions. K{sub y}a increases with the hydrogen flow rates in the range of 0.4-1.6 m s{sup -1} at STP. The height of the catalyst column was determined from these K{sub y}a values according to the reaction temperatures and hydrogen flow rates.

Preparation of Affinity Column Based on Zr4+ Ion for Phosphoproteins Isolation

International Nuclear Information System (INIS)

Lee, Seon Mi; Bae, In Ae; Park, Jung Hyen; Kim, Tae Dong; Choi, Seong Ho

2009-01-01

This paper has described about preparation of Zr 4+ affinity column based on the poly(styreneco- glycidyl methacrylate) prepared by emulsion polymerization of styrene and glycidyl methacrylate in order to isolate phosphopeptide. The Zr 4+ ions were introduced after the phophonation of an epoxy group on polymeric microspheres. The successful preparation of Zr 4+ -immobilized polymeric microsphere stationary phase was confirmed through Fourier transform infrared spectra, optical microscopy, scanning electron microscopy, X-ray photoelectron spectra and inductively coupled plasma-atomic emission spectrometer. The separation efficiency for Zr 4+ affinity column prepared by slurry packing was tested to phosphonated casein and dephosphonated casein. The resolution time (min) of the phosphonated casein was higher than that of dephosphated casein for Zr 4+ affinity polymeric microsphere by liquid chromatography. This Zr 4+ affinity column can be used for isolation of phosphonated casein from casein using liquid chromatography

Study of hydrodynamic and mass transfer parameters in pulsed sieve-plate columns

International Nuclear Information System (INIS)

Safdari, J.

2001-01-01

One of the most important liquid-liquid extractor in industry is pulsed column. The pulsed columns are generally classified into the following categories: 1-Pulsed perforated-plate column. 2- Pulsed packed column. The pulsed plate column is differential contactor with the application of mechanical energy and is used for a diverse range of processes. Probably its best known application has been in the nuclear fuel industry. The pulsed plate column consists of a cylindrical shell with settling zones at the top and the bottom of the column. The liquids are fed continuously to the column (flowing counter-currently) and are removed continuously from opposite ends of the column. In this work using a pilot pulsed plate column and two different chemical systems (toluene/acetone/water and n-butyl acetate/acetone/water) various experiments are carried out. In each experiment direction of mass transfer is from organic phase (dispersed phase) into aqueous phase (continuous phase) and the continuous phase is water. The main objects of this thesis are as follow: a- Investigation of effect of operating parameters on dispersed phase hold up, volumetric overall mass transfer coefficients based on dispersed and continuous phase, extraction efficiency, pressure drop of column and flooding velocities (maximum column capacities). Obtained results in this part show that if the calorimetric flow rate of aqueous phase or pulsation intensity increase, hold up, volumetric overall mass transfer coefficients based on both two phases and extraction efficiency will increase and flooding velocities will decrease. Also results show that if volumetric flow rate of organic phase increase, hold up, volumetric mass transfer coefficients based on both two phases and pressure drop will increase and extraction efficiency and flooding velocities will decrease. b- Investigation of effect of internal circulation inside drops in designing pulsed perforated-plate column

Tunable random packings

International Nuclear Information System (INIS)

Lumay, G; Vandewalle, N

2007-01-01

We present an experimental protocol that allows one to tune the packing fraction η of a random pile of ferromagnetic spheres from a value close to the lower limit of random loose packing η RLP ≅0.56 to the upper limit of random close packing η RCP ≅0.64. This broad range of packing fraction values is obtained under normal gravity in air, by adjusting a magnetic cohesion between the grains during the formation of the pile. Attractive and repulsive magnetic interactions are found to affect stongly the internal structure and the stability of sphere packing. After the formation of the pile, the induced cohesion is decreased continuously along a linear decreasing ramp. The controlled collapse of the pile is found to generate various and reproducible values of the random packing fraction η

A novel fiber-packed column for on-line preconcentration and speciation analysis of chromium in drinking water with flame atomic absorption spectrometry.

Science.gov (United States)

Monasterio, Romina P; Altamirano, Jorgelina C; Martínez, Luis D; Wuilloud, Rodolfo G

2009-02-15

A novel on-line preconcentration and determination system based on a fiber-packed column was developed for speciation analysis of Cr in drinking water samples prior to its determination by flame atomic absorption spectrometry (FAAS). All variables involved in the development of the preconcentration method including, pH, eluent type, sample and eluent flow rates, interfering effects, etc., were studied in order to achieve the best analytical performance. A preconcentration factor of 32 was obtained for Cr(VI) and Cr(III). The levels of Cr(III) species were calculated by difference of total Cr and Cr(VI) levels. Total Cr was determined after oxidation of Cr(III) to Cr(VI) with hydrogen peroxide. The calibration graph was linear with a correlation coefficient of 0.999 at levels near the detection limit and up to at least 50 microg L(-1). The relative standard deviation (R.S.D.) was 4.3% (C=5 microg L(-1) Cr(VI), n=10, sample volume=25 mL). The limit of detection (LOD) for both Cr(III) and Cr(VI) species was 0.3 microg L(-1). Verification of the accuracy was carried out by the analysis of a standard reference material (NIST SRM 1643e "Trace elements in natural water"). The method was successfully applied to the determination of Cr(III) and Cr(VI) species in drinking water samples.

Recent Advances and Uses of Monolithic Columns for the Analysis of Residues and Contaminants in Food

Directory of Open Access Journals (Sweden)

Mónica Díaz-Bao

2015-02-01

Full Text Available Monolithic columns are gaining interest as excellent substitutes to conventional particle-packed columns. These columns show higher permeability and lower flow resistance than conventional liquid chromatography columns, providing high-throughput performance, resolution and separation in short run times. Monoliths possess also great potential for the clean-up and preparation of complex mixtures. In situ polymerization inside appropriate supports allows the development of several microextraction formats, such as in-tube solid-phase and pipette tip-based extractions. These techniques using porous monoliths offer several advantages, including miniaturization and on-line coupling with analytical instruments. Additionally, monoliths are ideal support media for imprinting template-specific sites, resulting in the so-called molecularly-imprinted monoliths, with ultra-high selectivity. In this review, time-saving LC columns and preparative applications applied to the analysis of residues and contaminants in food in 2010–2014 are described, focusing on recent improvements in design and with emphasis in automated on-line systems and innovative materials and formats.

Preparation of Affinity Column Based on Zr{sup 4+} Ion for Phosphoproteins Isolation

Energy Technology Data Exchange (ETDEWEB)

Lee, Seon Mi; Bae, In Ae; Park, Jung Hyen; Kim, Tae Dong; Choi, Seong Ho [Hannam University, Daejeon (Korea, Republic of)

2009-06-15

This paper has described about preparation of Zr{sup 4+} affinity column based on the poly(styreneco- glycidyl methacrylate) prepared by emulsion polymerization of styrene and glycidyl methacrylate in order to isolate phosphopeptide. The Zr{sup 4+} ions were introduced after the phophonation of an epoxy group on polymeric microspheres. The successful preparation of Zr{sup 4+}-immobilized polymeric microsphere stationary phase was confirmed through Fourier transform infrared spectra, optical microscopy, scanning electron microscopy, X-ray photoelectron spectra and inductively coupled plasma-atomic emission spectrometer. The separation efficiency for Zr{sup 4+} affinity column prepared by slurry packing was tested to phosphonated casein and dephosphonated casein. The resolution time (min) of the phosphonated casein was higher than that of dephosphated casein for Zr{sup 4+} affinity polymeric microsphere by liquid chromatography. This Zr{sup 4+} affinity column can be used for isolation of phosphonated casein from casein using liquid chromatography.

Environmental Conditions Influencing Sorption of Inorganic Anions to Multiwalled Carbon Nanotubes Studied by Column Chromatography.

Science.gov (United States)

Metzelder, Florian; Schmidt, Torsten C

2017-05-02

Sorption to carbon-based nanomaterials is typically studied in batch experiments. An alternative method offering advantages to study sorption is column chromatography. Sorbent packed columns are used and sorption data are determined by relating sorbate retention to that of a nonretarded tracer. We have now for the first time applied this technique to study the influence of environmental conditions on sorption of inorganic anions (bromide, nitrite, nitrate, and iodide) to multiwalled carbon nanotubes. Deuterium oxide was used as nonretarded tracer. Sorption isotherms were best described by the Freundlich model. Sorption increased in the order bromide 4.5 the surface charge was negative, but sorption was still detectable at pH 6 and 9. Consequently, other forces than electrostatic attraction contributed to sorption. These forces may include H-bonding as indicated by sorption enthalpy determined by variation of column temperature. Overall, column chromatography represents a promising alternative in sorption studies to reveal sorbent properties.

Exogenous factors contributing to column bed heterogeneity: Part 1: Consequences of 'air' injections in liquid chromatography.

Science.gov (United States)

Samuelsson, Jörgen; Fornstedt, Torgny; Shalliker, Andrew

2015-08-07

It has been shown that not only the packing homogeneity, but also factors external to the column bed, such as, frits and distributors can have important effects on the column performance. This current communication is the first in a series focusing on the impact of exogenous factors on the column bed heterogeneity. This study is based on several observations by us and others that chromatographic runs often, for technical reasons, include more or less portions of air in the injections. It is therefore extremely important to find out the impact of air on the column performance, the reliability of the results derived from analyses where air was injected, and the effect on the column homogeneity. We used a photographic approach for visualising the air transport phenomena, and found that the air transport through the column is comprised of many different types of transport phenomena, such as laminal flow, viscous fingering like flows, channels and bulbs, and pulsations. More particularly, the air clouds within the column definitely interact in the adsorption, i.e. mobile phase adsorbed to the column surface is displaced. In addition, irrespective of the type of air transport phenomena, the air does not penetrate the column homogeneously. This process is strongly flow dependent. In this work we study air transport both in an analytical scale and a semi-prep column. Copyright © 2015. Published by Elsevier B.V.

Studies on transfer phenomena of tritium from liquid to gaseous phase in a successive catalyst and ordered packing system

International Nuclear Information System (INIS)

Bornea, Anisia; Cristescu, Ion; Zamfirache, Marius; Varlam, Carmen

2001-01-01

The processes for hydrogen isotope separation are very important for nuclear technology. One of the most important processes in tritium separation, is the water-hydrogen catalytic isotope exchange. In a column of isotope exchange, tritium is transferred from the liquid phase (tritiated heavy water) to the gaseous phase (hydrogen). In the experimental set-up, which was used, the column of catalytic isotope exchange is filled with successive layers of catalyst Pt/C/PtFe and B7 type ordered packing of phosphor bronze. The tritium transfer from liquid phase to water vapours, is achieved on ordered packing by distillation process: (DTO)L+(D 2 O)V → (D 2 O)L+(DTO)V. On the catalytic tritium transfer from water vapours to hydrogen gas is achieved by the catalytic isotopic exchange process: (DTO)V+(D 2 )G → (D 2 O)V+(DT)G. We analyzed the transfer phenomena of tritium in this system by using the experimental data obtained. The mathematical model presented in the paper allowed computing experimental data for testing the catalyst performances. The transfer equations are solved using the Runge - Kutta method. In this way the speed constants which characterized the isotopic exchange on the catalysis bed ks, and the distillation on the ordered packing kd, were expressed as function of experimental concentrations and hydrodynamic conditions. (authors)

Simultaneous removal of CO2 and H2S using MEA solution in a packed column absorber for biogas upgrading

Directory of Open Access Journals (Sweden)

Preecha Kasikamphaiboon

2013-12-01

Full Text Available Biogas production and utilization is an emerging alternative energy technology that has gained importance since the price of oil and gas has increased steadily over the last two decades. Biogas primarily consists of methane (CH4 and carbon dioxide (CO2 with smaller amounts of hydrogen sulfide (H2S and ammonia (NH3. For many applications the quality of biogas has to be improved. The main parameters that may require removal in upgrading systems are CO2 and H2S. This work presents the study of simultaneous absorption of CO2 and H2S by Monoethanolamine (MEA solution in a packed column. Simulated biogas containing 40% CO2 and 60% N2 and biogas generated from an anaerobic digestion plant were used as feed gas streams. The effects of gas flow rate, L/G ratio and absorbent concentration were investigated. The performance of the system was found to vary with process parameters. Increasing L/G ratio and MEA concentration causes the system efficiency to increase whereas increasing gas flow rate results in lower efficiency. An operating condition of L/G ratio of 83.3 ml/L, gas flow rate of 3 L/min and MEA concentration of 3 mol/L was found to remove more than 99.5% of CO2 and H2S from biogas. The volumetric overall mass-transfer coefficient (KGav for CO2 removal initially increases with increasing gas flow rate up to a certain value beyond which the coefficient becomes essentially constant. The KGav also increases with increasing L/G ratio throughout the range tested in this study.

LIQUID CHROMATOGRAPHIC / MASS SPECTROMETRIC DETERMINATION OF MORPHINE, CODEINE AND COCAINE IN HUMAN SERA USING A NEW INTERNAL SURFACE REVERSED PHASE COLUMN

OpenAIRE

Hattori, Hideki; Arinobu, Tetsuya; Iwai, Masae; Suzuki, Osamu; Seno, Hiroshi

2003-01-01

A new internal surface reversed phase column (Shim-pack MAYI-ODS) was used for analysis of morphine, codeine and cocaine in human sera by LC/MS/MS. The column enabled direct injection of crude biological samples without pretreatment realizing a rapid analytical procedure. Therecoveries of morphine, codeine and cocaine spiked into human sera were 50-60 %. The regression equations for morphine, codeine and cocaine in sera, using atropine as internal standard, showed good linearity in the ranges...

Fixed-bed column study for 90Sr removal from solution by sunflower straw

International Nuclear Information System (INIS)

Ai Lian; Luo Xuegang; Lin Xiaoyan; Li Wenming

2014-01-01

This paper deals with removal of strontium ions from solution by sunflower straw. Metal sorption performance of the packed column was assessed under variable operating conditions, such as, bed depths, flow rates and initial influent strontium concentration. It was found that the breakthrough time and the depletion time were extended with increase of bed heights but obviously shortened with increase of influent concentration and flow rates, respectively. The equilibrium uptake (q e(exp) ) of sunflower straw increased with increase in initial influent strontium concentration and flow rates but decreased with increase in bed depth, respectively. The data in regard to the effect of bed depths were fitted well to the Bohrat-Adams model. The saturated column was successfully regenerated by 0.1 mol/L hydrogen chloride solution and sunflower straw could be reused in strontium removal. The results indicated that the column could efficiently remove strontium ions from real industrial effluents, and hence the sunflower straw is a good candidate for commercial application. (authors)

Volatile Removal Assembly Flight Experiment and KC-135 Packed Bed Experiment: Results and Lessons Learned

Science.gov (United States)

Holder, Donald W.; Parker, David

2000-01-01

The Volatile Removal Assembly (VRA) is a high temperature catalytic oxidation process that will be used as the final treatment for recycled water aboard the International Space Station (ISS). The multiphase nature of the process had raised concerns as to the performance of the VRA in a microgravity environment. To address these concerns, two experiments were designed. The VRA Flight Experiment (VRAFE) was designed to test a full size VRA under controlled conditions in microgravity aboard the SPACEHAB module and in a 1 -g environment and compare the performance results. The second experiment relied on visualization of two-phase flow through small column packed beds and was designed to fly aboard NASA's microgravity test bed plane (KC-135). The objective of the KC-135 experiment was to understand the two-phase fluid flow distribution in a packed bed in microgravity. On Space Transportation System (STS) flight 96 (May 1999), the VRA FE was successfully operated and in June 1999 the KC-135 packed bed testing was completed. This paper provides an overview of the experiments and a summary of the results and findings.

Numerical analysis and optimisation of heavy water upgrading column

International Nuclear Information System (INIS)

Sankar, Rama; Ghosh, Brindaban; Bhanja, K.

2013-01-01

In the 'Pressurised Heavy Water' type of reactors, heavy water is used both as moderator and coolant. During operation of reactor downgraded heavy water is generated that needs to be upgraded for reuse in the reactor. When the isotopic purity of heavy water becomes less than 99.75%, it is termed as downgraded heavy water. Downgraded heavy water also contains impurity such as corrosion products, dirt, oil etc. Upgradation of downgraded heavy water is normally done in two steps: (i) Purification: In this step downgraded heavy water is first purified to remove corrosion products, dirt, oil, etc. and (ii) Upgradation of heavy water to increase its isotopic purity, this step is carried out by vacuum distillation of downgraded heavy water after purification. This project is aimed at mathematical modelling and numerical simulation of heavy water upgrading column. Modelling and simulation studies of the upgradation column are based on equilibrium stage model to evaluate the effect of feed location, pressure, feed composition, reflux ratio in the packed column for given reboiler and condenser duty of distillation column. State to stage modelling of two-phase two-component flow has constitutes the overall modelling of the column. The governing equations consist of stage-wise species and overall mass continuity and stage-wise energy balance. This results in tridigonal matrix equation for stage liquid fractions for heavy and light water. The stage-wise liquid flow rates and temperatures are governed by stage-wise mass and energy balance. The combined form of the corresponding governing equations, with the incorporation of thermodynamic equation of states, form a system of nonlinear equations. This system have been resolved numerically using modified Newton-Raphson method. A code in the MATLAB platform has been developed by on above numerical procedure. The optimisation of the column operating conditions is to be carried out based on parametric studies and analysis of different

Derringer desirability and kinetic plot LC-column comparison approach for MS-compatible lipopeptide analysis.

Science.gov (United States)

D'Hondt, Matthias; Verbeke, Frederick; Stalmans, Sofie; Gevaert, Bert; Wynendaele, Evelien; De Spiegeleer, Bart

2014-06-01

Lipopeptides are currently re-emerging as an interesting subgroup in the peptide research field, having historical applications as antibacterial and antifungal agents and new potential applications as antiviral, antitumor, immune-modulating and cell-penetrating compounds. However, due to their specific structure, chromatographic analysis often requires special buffer systems or the use of trifluoroacetic acid, limiting mass spectrometry detection. Therefore, we used a traditional aqueous/acetonitrile based gradient system, containing 0.1% (m/v) formic acid, to separate four pharmaceutically relevant lipopeptides (polymyxin B 1 , caspofungin, daptomycin and gramicidin A 1 ), which were selected based upon hierarchical cluster analysis (HCA) and principal component analysis (PCA). In total, the performance of four different C18 columns, including one UPLC column, were evaluated using two parallel approaches. First, a Derringer desirability function was used, whereby six single and multiple chromatographic response values were rescaled into one overall D -value per column. Using this approach, the YMC Pack Pro C18 column was ranked as the best column for general MS-compatible lipopeptide separation. Secondly, the kinetic plot approach was used to compare the different columns at different flow rate ranges. As the optimal kinetic column performance is obtained at its maximal pressure, the length elongation factor λ ( P max / P exp ) was used to transform the obtained experimental data (retention times and peak capacities) and construct kinetic performance limit (KPL) curves, allowing a direct visual and unbiased comparison of the selected columns, whereby the YMC Triart C18 UPLC and ACE C18 columns performed as best. Finally, differences in column performance and the (dis)advantages of both approaches are discussed.

Mass transfer in liquid phase catalytic exchange column of trickle bed type

International Nuclear Information System (INIS)

Yamanishi, Toshihiko; Iwai, Yasunori; Okuno, Kenji

1995-09-01

The mechanism of mass transfer in a liquid phase catalytic exchange column was discussed for a trickle bed type. A new model has been proposed on the basis of this mass transfer mechanism; and several problems for the previous reported models were pointed out in the derivation of the model. An overall rate equation was first derived from the vapor-hydrogen exchange in the model. The mass transfer for the vapor-hydrogen exchange was decomposed to the following three steps: the mass transfer in a gas boundary layer on a catalyst particle; the mass transfer within the pores in the catalyst; and the chemical reaction on the surface of the catalyst. The water-vapor scrubbing process was considered as a series of the mass transfers in gas and liquid boundary layers on the wetted surfaces of the catalyst and packings or wall of the column. Significant subjects to be studied were proposed from the viewpoint of the validity of the model and the optimization of the column. (author)

Unsaturated hydraulic conductivity of sandy soil columns packed to different bulk densities and water uptake by plantroots

NARCIS (Netherlands)

Rossi-Pisa, P.

1978-01-01

This paper describes a laboratory metbod used to determine both the soil moisture retention curve and the unsaturated hydraulic conductivity in soil columns under transient flow conditions during evaporation.

Comparing the efficacy of mature mud pack and hot pack treatments for knee osteoarthritis.

Science.gov (United States)

Sarsan, Ayşe; Akkaya, Nuray; Ozgen, Merih; Yildiz, Necmettin; Atalay, Nilgun Simsir; Ardic, Fusun

2012-01-01

The objective of this study is to compare the efficacy of mature mud pack and hot pack therapies on patients with knee osteoarthritis. This study was designed as a prospective, randomized-controlled, and single-blinded clinical trial. Twenty-seven patients with clinical and radiologic evidence of knee osteoarthritis were randomly assigned into two groups and were treated with mature mud packs (n 15) or hot packs (n=12). Patients were evaluated for pain [based on the visual analog scale (VAS)], function (WOMAC, 6 min walking distance), quality of life [Short Form-36 (SF-36)], and serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and insulin-like growth factor-1 (IGF-1) at baseline, post-treatment, and 3 and 6~months after treatment. The mud pack group shows a significant improvement in VAS, pain, stifness, and physical function domains of WOMAC. The difference between groups of pain and physical activity domains is significant at post-treatment in favor of mud pack. For a 6 min walking distance, mud pack shows significant improvement, and the difference is significant between groups in favor of mud pack at post-treatment and 3 and 6 months after treatment. Mud pack shows significant improvement in the pain subscale of SF-36 at the third month continuing until the sixth month after the treatment. Significant improvements are found for the social function, vitality/energy, physical role disability, and general health subscales of SF-36 in favor of the mud pack compared with the hot pack group at post-treatment. A significant increase is detected for IGF-1 in the mud pack group 3 months after treatment compared with the baseline, and the difference is significant between groups 3 months after the treatment. Mud pack is a favorable option compared with hotpack for pain relief and for the improvement of functional conditions in treating patients with knee osteoarthritis.

Plutonium-239 sorption and transport on/in unsaturated sediments. Comparison of batch and column experiments for determining sorption coefficients

International Nuclear Information System (INIS)

Jinchuan Xie; Jiachun Lu; Xiaohua Zhou; Xuhui Wang; Mei Li; Lili Du; Yueheng Liu; Guoqing Zhou

2013-01-01

Sorption (distribution) coefficients of plutonium were most often derived by static batch experiments. However, it is not clear how unsaturated flow conditions including moisture content and pore water velocity change the sorption coefficients. Transport experiments of plutonium through the unsaturated sediments packed into the columns were then performed in order to determine the sorption coefficients (column-K ds ). Static batch experiments were also conducted to obtain batch-K ds and then compare the differences between batch-K ds and column-K ds . The results show that unsaturated flow conditions had no significant effect on column-K ds , and the average column-K d value was 1.74 ± 0.02 m 3 /kg. By comparison, batch-K d values spanned several orders of magnitude, regardless of the specified liquid-solid conditions. Moreover, the batch-K d (22.7 m 3 /kg) at the standard L/S (4 mL/g) recommended by ASTM D 4319 was over an order of magnitude larger than the average column-K d . (author)

Argo packing friction research update

International Nuclear Information System (INIS)

VanTassell, D.M.

1994-01-01

This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

The hydrodynamic behaviour of gas—solid trickle flow over a regularly stacked packing

OpenAIRE

Verver, A.B.; van Swaaij, Willibrordus Petrus Maria

1986-01-01

The hydrodynamic properties of counter-current gas—solid flow over a regularly stacked packing at trickle flow conditions have been studied. The flow properties of the solids phase were examined, using five types of solid particles with a mean particle diameter ranging from 70 to 880 μm and a particle density from 800 to 7800 kg m−3. Data on the solids hold-up and the pressure drop caused by the solids flow were obtained from experiments in a test column of 0.10 m square cross-section. A part...

Minimum number of transfer units and reboiler duty for multicomponent distillation columns

International Nuclear Information System (INIS)

Pleşu, Valentin; Bonet Ruiz, Alexandra Elena; Bonet, Jordi; Llorens, Joan; Iancu, Petrica

2013-01-01

Some guidelines to evaluate distillation columns, considering only basic thermodynamic data and principles, are provided in this paper. The method allows a first insight to the problem by simple calculations, without requiring column variables to ensure rational use of energy and low environmental impact. The separation system is approached by two complementary ways: minimum and infinite reflux flow rate. The minimum reflux provides the minimum energy requirements, and the infinite reflux provides the feasibility conditions. The difficulty of separation can be expressed in terms of number of transfer units (NTU). The applicability of the method is not mathematically limited by the number of components in the mixture. It is also applicable to reactive distillation. Several mixtures, including reactive distillation, are rigorously simulated as illustrative examples, to verify the applicability of the approach. The separation of the mixtures, performed by distillation columns, is feasible if a minimum NTU can be calculated between the distillate and bottom products. Once verified the feasibility of the separation, the maximum thermal efficiency depends only on boiling point of bottom and distillate streams. The minimum energy requirements corresponding to the reboiler can be calculated from the maximum thermal efficiency, and the variation of entropy and enthalpy of mixing between distillate and bottom streams. -- Highlights: • Feasibility analysis complemented with difficulty of separation parameters • Minimum and infinite reflux simplified models for distillation columns • Minimum number of transfer units (NTU) for packed columns at early design stages • Calculation of minimum energy distillation requirements at early design stages • Thermodynamic cycle approach and efficiency for distillation columns

Packing force data correlations

International Nuclear Information System (INIS)

Heiman, S.M.

1994-01-01

One of the issues facing valve maintenance personnel today deals with an appropriate methodology for installing and setting valve packing that will minimize leak rates, yet ensure functionality of the the valve under all anticipated operating conditions. Several variables can affect a valve packing's ability to seal, such as packing bolt torque, stem finish, and lubrication. Stem frictional force can be an excellent overall indicator of some of the underlying conditions that affect the sealing characteristics of the packing and the best parameter to use when adjusting the packing. This paper addresses stem friction forces, analytically derives the equations related to these forces, presents a methodology for measuring these forces on valve stems, and attempts to correlate the data directly to the underlying variables

Integrated Multiscale Latent Variable Regression and Application to Distillation Columns

Directory of Open Access Journals (Sweden)

Muddu Madakyaru

2013-01-01

Full Text Available Proper control of distillation columns requires estimating some key variables that are challenging to measure online (such as compositions, which are usually estimated using inferential models. Commonly used inferential models include latent variable regression (LVR techniques, such as principal component regression (PCR, partial least squares (PLS, and regularized canonical correlation analysis (RCCA. Unfortunately, measured practical data are usually contaminated with errors, which degrade the prediction abilities of inferential models. Therefore, noisy measurements need to be filtered to enhance the prediction accuracy of these models. Multiscale filtering has been shown to be a powerful feature extraction tool. In this work, the advantages of multiscale filtering are utilized to enhance the prediction accuracy of LVR models by developing an integrated multiscale LVR (IMSLVR modeling algorithm that integrates modeling and feature extraction. The idea behind the IMSLVR modeling algorithm is to filter the process data at different decomposition levels, model the filtered data from each level, and then select the LVR model that optimizes a model selection criterion. The performance of the developed IMSLVR algorithm is illustrated using three examples, one using synthetic data, one using simulated distillation column data, and one using experimental packed bed distillation column data. All examples clearly demonstrate the effectiveness of the IMSLVR algorithm over the conventional methods.

Ultra high pressure liquid chromatography. Column permeability and changes of the eluent properties.

Science.gov (United States)

Gritti, Fabrice; Guiochon, Georges

2008-04-11

The behavior of four similar liquid chromatography columns (2.1mm i.d. x 30, 50, 100, and 150 mm, all packed with fine particles, average d(p) approximately 1.7 microm, of bridged ethylsiloxane/silica hybrid-C(18), named BEH-C(18)) was studied in wide ranges of temperature and pressure. The pressure and the temperature dependencies of the viscosity and the density of the eluent (pure acetonitrile) along the columns were also derived, using the column permeabilities and applying the Kozeny-Carman and the heat balance equations. The heat lost through the external surface area of the chromatographic column was directly derived from the wall temperature of the stainless steel tube measured with a precision of +/-0.2 degrees C in still air and +/-0.1 degrees C in the oven compartment. The variations of the density and viscosity of pure acetonitrile as a function of the temperature and pressure was derived from empirical correlations based on precise experimental data acquired between 298 and 373 K and at pressures up to 1.5 kbar. The measurements were made with the Acquity UPLC chromatograph that can deliver a maximum flow rate of 2 mL/min and apply a maximum column inlet pressure of 1038 bar. The average Kozeny-Carman permeability constant of the columns was 144+/-3.5%. The temperature hence the viscosity and the density profiles of the eluent along the column deviate significantly from linear behavior under high-pressure gradients. For a 1000 bar pressure drop, we measured DeltaT=25-30 K, (Deltaeta/eta) approximately 100%, and (Deltarho/rho) approximately 10%. These results show that the radial temperature profiles are never fully developed within 1% for any of the columns, even under still-air conditions. This represents a practical advantage regarding the apparent column efficiency at high flow rates, since the impact of the differential analyte velocity between the column center and the column wall is not maximum. The interpretation of the peak profiles recorded in

A Microfluidic Device for Preparing Next Generation DNA Sequencing Libraries and for Automating Other Laboratory Protocols That Require One or More Column Chromatography Steps

Science.gov (United States)

Tan, Swee Jin; Phan, Huan; Gerry, Benjamin Michael; Kuhn, Alexandre; Hong, Lewis Zuocheng; Min Ong, Yao; Poon, Polly Suk Yean; Unger, Marc Alexander; Jones, Robert C.; Quake, Stephen R.; Burkholder, William F.

2013-01-01

Library preparation for next-generation DNA sequencing (NGS) remains a key bottleneck in the sequencing process which can be relieved through improved automation and miniaturization. We describe a microfluidic device for automating laboratory protocols that require one or more column chromatography steps and demonstrate its utility for preparing Next Generation sequencing libraries for the Illumina and Ion Torrent platforms. Sixteen different libraries can be generated simultaneously with significantly reduced reagent cost and hands-on time compared to manual library preparation. Using an appropriate column matrix and buffers, size selection can be performed on-chip following end-repair, dA tailing, and linker ligation, so that the libraries eluted from the chip are ready for sequencing. The core architecture of the device ensures uniform, reproducible column packing without user supervision and accommodates multiple routine protocol steps in any sequence, such as reagent mixing and incubation; column packing, loading, washing, elution, and regeneration; capture of eluted material for use as a substrate in a later step of the protocol; and removal of one column matrix so that two or more column matrices with different functional properties can be used in the same protocol. The microfluidic device is mounted on a plastic carrier so that reagents and products can be aliquoted and recovered using standard pipettors and liquid handling robots. The carrier-mounted device is operated using a benchtop controller that seals and operates the device with programmable temperature control, eliminating any requirement for the user to manually attach tubing or connectors. In addition to NGS library preparation, the device and controller are suitable for automating other time-consuming and error-prone laboratory protocols requiring column chromatography steps, such as chromatin immunoprecipitation. PMID:23894273

A microfluidic device for preparing next generation DNA sequencing libraries and for automating other laboratory protocols that require one or more column chromatography steps.

Directory of Open Access Journals (Sweden)

Swee Jin Tan

Full Text Available Library preparation for next-generation DNA sequencing (NGS remains a key bottleneck in the sequencing process which can be relieved through improved automation and miniaturization. We describe a microfluidic device for automating laboratory protocols that require one or more column chromatography steps and demonstrate its utility for preparing Next Generation sequencing libraries for the Illumina and Ion Torrent platforms. Sixteen different libraries can be generated simultaneously with significantly reduced reagent cost and hands-on time compared to manual library preparation. Using an appropriate column matrix and buffers, size selection can be performed on-chip following end-repair, dA tailing, and linker ligation, so that the libraries eluted from the chip are ready for sequencing. The core architecture of the device ensures uniform, reproducible column packing without user supervision and accommodates multiple routine protocol steps in any sequence, such as reagent mixing and incubation; column packing, loading, washing, elution, and regeneration; capture of eluted material for use as a substrate in a later step of the protocol; and removal of one column matrix so that two or more column matrices with different functional properties can be used in the same protocol. The microfluidic device is mounted on a plastic carrier so that reagents and products can be aliquoted and recovered using standard pipettors and liquid handling robots. The carrier-mounted device is operated using a benchtop controller that seals and operates the device with programmable temperature control, eliminating any requirement for the user to manually attach tubing or connectors. In addition to NGS library preparation, the device and controller are suitable for automating other time-consuming and error-prone laboratory protocols requiring column chromatography steps, such as chromatin immunoprecipitation.

Sorption-enhanced water gas shift reaction for high-purity hydrogen production: Application of a Na-Mg double salt-based sorbent and the divided section packing concept

International Nuclear Information System (INIS)

Lee, Chan Hyun; Lee, Ki Bong

2017-01-01

Highlights: •Na-Mg double salt-based sorbent was used for high-temperature CO 2 sorption. •Divided section packing concept was applied to the SE-WGS reaction. •High-purity H 2 was produced from the SE-WGS reaction with divided section packing. •High-purity H 2 productivity could be further enhanced by modifying packing method. -- Abstract: Hydrogen is considered a promising environmentally benign energy carrier because it has high energy density and produces no pollutants when it is converted into other types of energy. The sorption-enhanced water gas shift (SE-WGS) reaction, where the catalytic WGS reaction and byproduct CO 2 removal are carried out simultaneously in a single reactor, has received considerable attention as a novel method for high-purity hydrogen production. Since the high-purity hydrogen productivity of the SE-WGS reaction is largely dependent on the performance of the CO 2 sorbent, the development of sorbents having high CO 2 sorption capacity is crucial. Recently, a Na-Mg double salt-based sorbent has been considered for high-temperature CO 2 capture since it has been reported to have a high sorption capacity and fast sorption kinetics. In this study, the SE-WGS reaction was experimentally demonstrated using a commercial catalyst and a Na-Mg double salt-based sorbent. However, the SE-WGS reaction with a one-body hybrid solid, a physical admixture of catalyst and sorbent, showed poor reactivity and reduced CO 2 sorption uptake. As a result, a divided section packing concept was suggested as a solution. In the divided section packing method, the degree of mixing for the catalyst and sorbent in a column can be controlled by the number of sections. High-purity hydrogen (<10 ppm CO) was produced directly from the SE-WGS reaction with divided section packing, and the hydrogen productivity was further improved when the reactor column was divided into more sections and packed with more sorbent.

Retention behavior of neutral solutes in pressurized flow-driven capillary electrochromatography using an ODS column.

Science.gov (United States)

Nakagawa, Hiroyuki; Kitagawa, Shinya; Araki, Shuki; Ohtani, Hajime

2006-02-01

Several alkyl benzenes are separated by pressurized flow-driven capillary electrochromatography using a temperature-controlled capillary column packed with octadecyl siloxane-modified silica gel, and the effect of applied voltage on the retention is investigated. The van't Hoff plot shows good linearity at the column temperature between 305 and 330 K under applications from -6 to +6 kV. The applied voltage causes a relatively large variation in the enthalpy and the entropy of transfer of the solute from the mobile phase to the stationary phase (> 20%). However, the direction of variation in the enthalpy is almost opposite to that in the entropy, both of which might compensate each other. Therefore, the retention factor is not significantly varied (< 4%) by the application of voltage.

American Spirit Pack Descriptors and Perceptions of Harm: A Crowdsourced Comparison of Modified Packs.

Science.gov (United States)

Pearson, Jennifer L; Richardson, Amanda; Feirman, Shari P; Villanti, Andrea C; Cantrell, Jennifer; Cohn, Amy; Tacelosky, Michael; Kirchner, Thomas R

2016-08-01

In 2015, the Food and Drug Administration issued warnings to three tobacco manufacturers who label their cigarettes as "additive-free" and/or "natural" on the grounds that they make unauthorized reduced risk claims. The goal of this study was to examine US adults' perceptions of three American Spirit (AS) pack descriptors ("Made with Organic Tobacco," "100% Additive-Free," and "100% US Grown Tobacco") to assess if they communicate reduced risk. In September 2012, three cross-sectional surveys were posted on Amazon Mechanical Turk. Adult participants evaluated the relative harm of a Marlboro Red pack versus three different AS packs with the descriptors "Made with Organic Tobacco," "100% Additive-Free," or "100% US Grown Tobacco" (Survey 1; n = 461); a Marlboro Red pack versus these AS packs modified to exclude descriptors (Survey 2; n = 857); and unmodified versus modified AS pack images (Survey 3; n = 1001). The majority of Survey 1 participants rated the unmodified AS packs as less harmful than the Marlboro Red pack; 35.4%-58.8% of Survey 2 participants also rated the modified (no claims) packs as less harmful than Marlboro Red. In these surveys, prior use of AS cigarettes was associated with reduced perceptions of risk (adjusted odds ratio [AOR] 1.59-2.40). "Made with Organic Tobacco" and "100% Additive-Free" were associated with reduced perceptions of risk when comparing the modified versus the unmodified AS packs (Survey 3). Data suggest that these AS pack descriptors communicate reduced harm messages to consumers. Findings have implications for regulatory actions related to product labeling and packaging. These findings provide additional evidence that the "Made with Organic Tobacco," "100% Additive-Free," and "100% US Grown" descriptors, as well as other aspects of the AS pack design, communicate reduced harm to non-, current, and former smokers. Additionally, they provide support for the importance of FDA's 2015 warning to Santa Fe Natural Tobacco Company on

Validity of using modified capillary column with larger diameter to study the Cs diffusion in local Taiwan laterite

International Nuclear Information System (INIS)

Tsing-Hai Wang; National Tsing Hua University, Hsinchu, Taiwan; Wen-Chun Yeh; Shih-Chin Tsai; Yi-Lin Jan; Shi-Ping Teng

2008-01-01

We have examined the working diameter of capillary columns with diameter of 5, 7, 10 and 20 mm. These modified capillary columns were carefully filled with local Taiwan laterite (LTL). The porosity and density of these packed columns was 0.51±0.02 g/g and 1.27±0.05 g/cm 3 , respectively. The diffusion experiments were then carried out in synthetic groundwater with Cs loading of 0.1mM at room temperature. Experimental results have shown that the diffusion profiles of modified capillary columns fit Fick's second law very well. This result revealed that the working diameter of a capillary column can be expanded to at least to 20 mm without affecting the validity of the derived diffusion coefficients. Among these columns, the ones with 5 mm diameter show the most consistent results of the derived K d , apparent and effective diffusion coefficients. Although the derived distribution and effective diffusion coefficients slightly decrease as the diameter of these columns increases due to the increase of the solid/liquid ratio. These values are still informative of the Cs diffusion in local Taiwan laterite. Moreover, our results clearly demonstrate the potential of using 'modified capillary method' to study the diffusion behaviors of concerned radionuclide because columns with large diameter enable the filling with more versatile geological substances. (author)

Moisture removal rate for air dehumidification by triethylene glycol in a structured packed column

International Nuclear Information System (INIS)

Elsarrag, Esam

2007-01-01

In this investigation, a desiccant dehumidifier is tested for different ranges of liquid to air flow rate ratios to expand the validity range of the results. Theoretical and experimental studies of the simultaneous heat and mass transfer to evaluate the moisture removal rate are conducted. The model predictions are compared with experimental results with very good agreement. Through the experimental study, the important design variables that affect the moisture removal rate are defined and compared with previous studies. The correlation found in the literature is assessed, and the errors are reported. The parameters that are varied during the experiments included the air and liquid flow rates, the air humidity ratio, the desiccant equilibrium humidity and the packing height. It is found that the liquid flow rate has no significant effect on the moisture removal rate when the liquid to air flow ratio has exceeded the value of 2

The adsorption of copper in a packed-bed of chitosan beads: Modeling, multiple adsorption and regeneration

OpenAIRE

Neomagus, Hein W J P; Osifo, Peter O; Everson, Raymond C; Webster, Athena; Gun, Marius A

2009-01-01

In this study, exoskeletons of Cape rock lobsters were used as raw material in the preparation of chitin that was successively deacetylated to chitosan flakes. The chitosan flakes were modified into chitosan beads and the beads were cross-linked with glutaraldehyde in order to study copper adsorption and regeneration in a packed-bed column. Five consecutive adsorption and desorption cycles were carried out and a chitosan mass loss of 25% was observed, after the last cycle. Despite the loss of...

Hardness of approximation for strip packing

DEFF Research Database (Denmark)

Adamaszek, Anna Maria; Kociumaka, Tomasz; Pilipczuk, Marcin

2017-01-01

Strip packing is a classical packing problem, where the goal is to pack a set of rectangular objects into a strip of a given width, while minimizing the total height of the packing. The problem has multiple applications, for example, in scheduling and stock-cutting, and has been studied extensively......)-approximation by two independent research groups [FSTTCS 2016,WALCOM 2017]. This raises a questionwhether strip packing with polynomially bounded input data admits a quasi-polynomial time approximation scheme, as is the case for related twodimensional packing problems like maximum independent set of rectangles or two...

Modified strip packing heuristics for the rectangular variable-sized bin packing problem

Directory of Open Access Journals (Sweden)

FG Ortmann

2010-06-01

Full Text Available Two packing problems are considered in this paper, namely the well-known strip packing problem (SPP and the variable-sized bin packing problem (VSBPP. A total of 252 strip packing heuristics (and variations thereof from the literature, as well as novel heuristics proposed by the authors, are compared statistically by means of 1170 SPP benchmark instances in order to identify the best heuristics in various classes. A combination of new heuristics with a new sorting method yields the best results. These heuristics are combined with a previous heuristic for the VSBPP by the authors to find good feasible solutions to 1357 VSBPP benchmark instances. This is the largest statistical comparison of algorithms for the SPP and the VSBPP to the best knowledge of the authors.

Permeability change with dissolution and precipitation reaction induced by highly alkaline plume in packed bed with amorphous silica particles

International Nuclear Information System (INIS)

Komatsu, Kyo; Kadowaki, Junichi; Niibori, Yuichi; Mimura, Hitoshi; Usui, Hideo

2008-01-01

A large amount of cement is used to construct of the geological disposal system. Such a material alters the pH of groundwater to highly alkaline region. The highly alkaline plume contains rich Ca ion compared to the surrounding environment, and the Ca ion reacts with soluble silicic acid. Its product would deposit on the surface of flow-paths in the natural barrier and decrease the permeability. In this study, the influence of Ca ions in highly alkaline plume on flow-paths has been examined by using packed bed column. The column was packed with the amorphous silica particles of 75-150 μm in diameter. The Ca(OH) 2 solution (0.78 mM, 2.58 mM, 4.37 mM, and 8.48 mM, pH: 12.2-12.4) was continuously injected into the column at a constant flow rate (5 ml/min, and 2 ml/min), and the change of permeability was monitored. At the same time, the concentrations of [Ca] total and [Si] in the eluted solution were measured by the inductively coupled plasma atomic emission spectrometry (ICP-AES). The Ca(OH) 2 solutions were prepared with CO 2 -free pure water, and filtrated through 0.45 μm filter. The permeability was normalized by the initial permeability value. In the experiment results, the permeability dramatically changed with increasing Ca concentration, because Ca ions and H 4 SiO 4 (due to the dissolution of SiO 2 ) produce C-S-H gel between the packed particles in the column. The SEM images and XRD analyses showed that the surface of SiO 2 particles was covered with the C-S-H gel precipitation. On the other hand, when the Ca concentration was relatively low, the permeability did not show remarkable change. For the cross section of SiO 2 particles, EPMA analysis suggested the consumption of Ca in the inner pore of the SiO 2 particles. However, the time-change in the concentrations of Si and Ca was not always simple. Such time-change strongly depended not only on pH or Ca concentration, but also on the flow rates. This suggested that mass transport controls the chemical

The advantages of hydraulic packing extraction

International Nuclear Information System (INIS)

Baker, R.S.

1991-01-01

Today's competitive environment, coupled with industry's desire to improve the efficiency of plant maintenance and operations, has management continually seeking ways to save time, money, and, at nuclear plants, radiation exposure. One area where a tremendous improvement in efficiency can be realized is valve packing removal. For example, industry experience indicates that up to 70% of the time it takes to repack a valve can be spent just removing the old packing. In some case, the bonnets of small valves are removed to facilitate packing removal and prevent stem and stuffing box damage that can occur when using packing removal picks. In other cases, small valves are simply removed and discarded because it costs less to replace the valves than to remove the packing using conventional methods. Hydraulic packing extraction greatly reduces packing removal time and will not damage the stem nor stuffing box, thus eliminating the need for bonnet removal or valve replacement. This paper will review some of the more common problems associated with manual packing extraction techniques. It will explain how hydraulic packing extraction eliminates or greatly reduces the impact of each of the problem areas. A discussion will be provided of some actual industry operating experiences related to success stories using hydraulic packing extraction. The paper will also briefly describe the operating parameters associated with hydraulic packing extraction tools. Throughout the paper, actual operating experiences from the nuclear power, fossil power, petrochemical, and refinery industries will be used to support the conclusion that hydraulic packing extraction is an alternative that can save time, money, and exposure

1.9 μm superficially porous packing material with radially oriented pores and tailored pore size for ultra-fast separation of small molecules and biomolecules.

Science.gov (United States)

Min, Yi; Jiang, Bo; Wu, Ci; Xia, Simin; Zhang, Xiaodan; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2014-08-22

In this work, 1.9 μm reversed-phase packing materials with superficially porous structure were prepared to achieve the rapid and high efficient separation of peptides and proteins. The silica particles were synthesized via three steps, nonporous silica particle preparation by a modified seeded growth method, mesoporous shell formation by a one pot templated dissolution and redeposition strategy, and pore size expansion via acid-refluxing. By such a method, 1.9 μm superficially porous materials with 0.18 μm shell thickness and tailored pore diameter (10 nm, 15 nm) were obtained. After pore enlargement, the formerly dense arrays of mesoporous structure changed, the radially oriented pores dominated the superficially porous structure. The chromatographic performance of such particles was investigated after C18 derivatization. For packing materials with 1.9 μm diameter and 10 nm pore size, the column efficiency could reach 211,300 plates per m for naphthalene. To achieve the high resolution separation of peptides and proteins, particles with pore diameter of 15 nm were tailored, by which the baseline separation of 5 peptides and 5 intact proteins could be respectively achieved within 1 min, demonstrating the superiority in the high efficiency and high throughput analysis of biomolecules. Furthermore, BSA digests were well separated with peak capacity of 120 in 30 min on a 15 cm-long column. Finally, we compared our columns with a 1.7 μm Kinetex C18 column under the same conditions, our particles with 10nm pore size demonstrated similar performance for separation of the large intact proteins. Moreover, the particles with 15 nm pore size showed more symmetrical peaks for the separation of large proteins (BSA, OVA and IgG) and provided rapid separation of protein extracts from Escherichia coli in 5 min. All these results indicated that the synthesized 1.9 μm superficially porous silica packing materials would be promising in the ultra-fast and high

The Maximum Resource Bin Packing Problem

DEFF Research Database (Denmark)

Boyar, J.; Epstein, L.; Favrholdt, L.M.

2006-01-01

Usually, for bin packing problems, we try to minimize the number of bins used or in the case of the dual bin packing problem, maximize the number or total size of accepted items. This paper presents results for the opposite problems, where we would like to maximize the number of bins used...... algorithms, First-Fit-Increasing and First-Fit-Decreasing for the maximum resource variant of classical bin packing. For the on-line variant, we define maximum resource variants of classical and dual bin packing. For dual bin packing, no on-line algorithm is competitive. For classical bin packing, we find...

Systematic evaluation of commercially available ultra-high performance liquid chromatography columns for drug metabolite profiling: optimization of chromatographic peak capacity.

Science.gov (United States)

Dubbelman, Anne-Charlotte; Cuyckens, Filip; Dillen, Lieve; Gross, Gerhard; Hankemeier, Thomas; Vreeken, Rob J

2014-12-29

The present study investigated the practical use of modern ultra-high performance liquid chromatography (UHPLC) separation techniques for drug metabolite profiling, aiming to develop a widely applicable, high-throughput, easy-to-use chromatographic method, with a high chromatographic resolution to accommodate simultaneous qualitative and quantitative analysis of small-molecule drugs and metabolites in biological matrices. To this end, first the UHPLC system volume and variance were evaluated. Then, a mixture of 17 drugs and various metabolites (molecular mass of 151-749Da, logP of -1.04 to 6.7), was injected on six sub-2μm particle columns. Five newest generation core shell technology columns were compared and tested against one column packed with porous particles. Two aqueous (pH 2.7 and 6.8) and two organic mobile phases were evaluated, first with the same flow and temperature and subsequently at each column's individual limit of temperature and pressure. The results demonstrated that pre-column dead volume had negligible influence on the peak capacity and shape. In contrast, a decrease in post-column volume of 57% resulted in a substantial (47%) increase in median peak capacity and significantly improved peak shape. When the various combinations of stationary and mobile phases were used at the same flow rate (0.5mL/min) and temperature (45°C), limited differences were observed between the median peak capacities, with a maximum of 26%. At higher flow though (up to 0.9mL/min), a maximum difference of almost 40% in median peak capacity was found between columns. The finally selected combination of solid-core particle column and mobile phase composition was chosen for its selectivity, peak capacity, wide applicability and peak shape. The developed method was applied to rat hepatocyte samples incubated with the drug buspirone and demonstrated to provide a similar chromatographic resolution, but a 6 times higher signal-to-noise ratio than a more traditional UHPLC

Removal of radium-226 from radium-contaminated soil using humic acid by column leaching method

International Nuclear Information System (INIS)

Esther Phillip; Muhamad Samudi Yasir

2012-01-01

In this study, evaluation of radium-226 removal from radium-contaminated soil using humic acid extracted from peat soil by column leaching method was carried out. Humic acid of concentration 100 ppm and pH 7 was leached through a column packed with radium-contaminated soil and leachates collected were analysed with gamma spectrometer to determine the leached radium-226. Results obtained indicated low removal of radium-226 between 1 - 4 %. Meanwhile, leaching profile revealed that radium-226 was bound to soil components with three different strength, thus resulting in three phases of radium-226 removal. It was estimated that the total removal of radium-226 from 10 g radium-contaminated soil sample studied could be achieved using approximately 31500 - 31850 ml HA solutions with leaching rate of 1 ml/ min. (author)

Valve packing manual. A maintenance application guide

International Nuclear Information System (INIS)

Aikin, J.A.; McCutcheon, R.G.; Cumming, D.

1997-01-01

Since 1970, AECL Chalk River Mechanical Equipment Development (MED) branch has invested over 175 person years in testing related to improving valve packing performance. Successful developments, including, 'live-loading', reduced packing heights, and performance-based packing qualification testing have been implemented. Since 1986, MED and the Integrated Valve Actuator Program Task Force - Valve Packing Steering Committee (IVAP-VPSC) have been involved in the development of combination die-formed graphite packing for use in CANDU plants. Many reports, articles, and specifications have been issued. Due to the large amount of test data and reports, a more user-friendly document has been prepared for everyday use. The Valve Packing Manual is based on many years of MED research and testing, as well as operating experience from CANDU nuclear generating stations (NGS). Since 1986, packing research and testing has been funded by the CANDU Owners Group (COG), the Electric Power Research Institute (EPRI), and participating valve packing manufacturers. The Valve Packing Manual (VPM) provides topical summaries of all work related to valve packing done since 1985. It includes advances in configuration design, stem packing friction, materials specifications, and installation procedures. This paper provides an overview on the application of the VPM with a focus on qualification testing, packing configuration, and stem packing friction. (author)

Experimental studies on the coolability of packed beds. Flooding of hot dry packed beds

International Nuclear Information System (INIS)

Leininger, S.; Kulenovic, R.; Laurien, E.

2013-01-01

In case of a severe accident in a nuclear power plant meltdown of the reactor core can occur and form a packed bed in the lower plenum of the reactor pressure vessel (RPV) after solidification due to contact with water. The removal of after-heat and the long-term coolability is of essential interest. The efficient injection of cooling water into the packed bed has to be assured without endangering the structural integrity of the reactor pressure vessel. The experiments performed aimed to study the dry-out and the quenching (flooding) of hot dry packed beds. Two different inflow variants, bottom- and top-flooding including the variation of the starting temperature of the packed bed and the injection rate were studied. In case of bottom flooding the quenching time increases with increasing packed bed temperature and decreasing injection rate. In case of top flooding the flow pattern is more complex, in a first phase the water flows preferentially toward the RPV wall, the flow paths conduct the water downwards. The flow resistance of the packed bed increases with increasing bed temperatures. The quenching temperatures increase significantly above average.

Oxidation of SO{sub 2} in a trickle bed reactor packed with activated carbon at low liquid flow rates

Energy Technology Data Exchange (ETDEWEB)

Suyadal, Y.; Oguz, H. [Ankara Univ. (Turkey). Dept. of Chemical Engineering

2000-07-01

In this study, the oxidation of SO{sub 2} on activated carbon (AcC) by using distilled water and air was carried out in a laboratory scale trickle bed reactor (TBR). Distilled water and air containing 1.7% (v/v) SO{sub 2} were fed co-currently downward through a fixed bed of AcC particles in a range of 1-7 cm{sup 3}/s and 10-27 cm{sup 3}/s, respectively. H{sub 2}SO{sub 3}/H{sub 2}SO{sub 4} solutions were the products obtained in the liqiuid phase. Steady-state experiments were performed in a column of 0.15 m packing height and 0.047 m column diameter at 20 C and atmospheric pressure. (orig.)

Separation of cannabinoids on three different mixed-mode columns containing carbon/nanodiamond/amine-polymer superficially porous particles.

Science.gov (United States)

Hung, Chuan-Hsi; Zukowski, Janusz; Jensen, David S; Miles, Andrew J; Sulak, Clayton; Dadson, Andrew E; Linford, Matthew R

2015-09-01

Three mixed-mode high-performance liquid chromatography columns packed with superficially porous carbon/nanodiamond/amine-polymer particles were used to separate mixtures of cannabinoids. Columns evaluated included: (i) reversed phase (C18 ), weak anion exchange, 4.6 × 33 mm, 3.6 μm, and 4.6 × 100 mm, 3.6 μm, (ii) reversed phase, strong anion exchange (quaternary amine), 4.6×33 mm, 3.6 μm, and (iii) hydrophilic interaction liquid chromatography, 4.6 × 150 mm, 3.6 μm. Different selectivities were achieved under various mobile phase and stationary phase conditions. Efficiencies and peak capacities were as high as 54 000 N/m and 56, respectively. The reversed phase mixed-mode column (C18 ) retained tetrahydrocannabinolic acid strongly under acidic conditions and weakly under basic conditions. Tetrahydrocannabinolic acid was retained strongly on the reversed phase, strong anion exchange mixed-mode column under basic polar organic mobile phase conditions. The hydrophilic interaction liquid chromatography column retained polar cannabinoids better than the (more) neutral ones under basic conditions. A longer reversed phase (C18 ) mixed-mode column (4.6 × 100 mm) showed better resolution for analytes (and a contaminant) than a shorter column. Fast separations were achieved in less than 5 min and sometimes 2 min. A real world sample (bubble hash extract) was also analyzed by gradient elution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ecology of southern ocean pack ice.

Science.gov (United States)

Brierley, Andrew S; Thomas, David N

2002-01-01

Around Antarctica the annual five-fold growth and decay of sea ice is the most prominent physical process and has a profound impact on marine life there. In winter the pack ice canopy extends to cover almost 20 million square kilometres--some 8% of the southern hemisphere and an area larger than the Antarctic continent itself (13.2 million square kilometres)--and is one of the largest, most dynamic ecosystems on earth. Biological activity is associated with all physical components of the sea-ice system: the sea-ice surface; the internal sea-ice matrix and brine channel system; the underside of sea ice and the waters in the vicinity of sea ice that are modified by the presence of sea ice. Microbial and microalgal communities proliferate on and within sea ice and are grazed by a wide range of proto- and macrozooplankton that inhabit the sea ice in large concentrations. Grazing organisms also exploit biogenic material released from the sea ice at ice break-up or melt. Although rates of primary production in the underlying water column are often low because of shading by sea-ice cover, sea ice itself forms a substratum that provides standing stocks of bacteria, algae and grazers significantly higher than those in ice-free areas. Decay of sea ice in summer releases particulate and dissolved organic matter to the water column, playing a major role in biogeochemical cycling as well as seeding water column phytoplankton blooms. Numerous zooplankton species graze sea-ice algae, benefiting additionally because the overlying sea-ice ceiling provides a refuge from surface predators. Sea ice is an important nursery habitat for Antarctic krill, the pivotal species in the Southern Ocean marine ecosystem. Some deep-water fish migrate to shallow depths beneath sea ice to exploit the elevated concentrations of some zooplankton there. The increased secondary production associated with pack ice and the sea-ice edge is exploited by many higher predators, with seals, seabirds and whales

Comparison of LC Columns Packed with 2.6 lm Core-Shell and Sub-2 lm Porous Particles for Gradient Separation of Antibiotics

Czech Academy of Sciences Publication Activity Database

Tylová, Tereza; Kameník, Zdeněk; Flieger, Miroslav; Olšovská, Jana

2011-01-01

Roč. 74, 1-2 (2011), s. 19-27 ISSN 0009-5893 R&D Projects: GA MŠk 1M06011 Institutional research plan: CEZ:AV0Z50200510 Keywords : Column liquid chromatography * Sub-2 mu m particles * Acquity BEH C18 column Subject RIV: EE - Microbiology, Virology Impact factor: 1.195, year: 2011

Optimized packings with applications

CERN Document Server

Pintér, János

2015-01-01

This volume presents a selection of case studies that address a substantial range of optimized object packings (OOP) and their applications. The contributing authors are well-recognized researchers and practitioners. The mathematical modelling and numerical solution aspects of each application case study are presented in sufficient detail. A broad range of OOP problems are discussed: these include various specific and non-standard container loading and object packing problems, as well as the stowing of hazardous and other materials on container ships, data centre resource management, automotive engineering design, space station logistic support, cutting and packing problems with placement constraints, the optimal design of LED street lighting, robust sensor deployment strategies, spatial scheduling problems, and graph coloring models and metaheuristics for packing applications. Novel points of view related to model development and to computational nonlinear, global, mixed integer optimization and heuristic st...

Design and research of seal structure for thermocouple column assembly

International Nuclear Information System (INIS)

Rao Qiqi; Li Na; Zhao Wei; Ma Zhigang

2015-01-01

The new seal structure was designed to satisfy the function of thermocouple column assembly and the reactor structure. This seal structure uses the packing graphite ring and adopts the self-sealing principle. Cone angle is brought to the seal face of seal structure which is conveniently to assembly and disassembly. After the sealing principle analysis and stress calculation of graphite ring which adopt the cone angle, the cone angle increases the radial force of seal structure and improves the seal effect. The stress analysis result shows the seal structure strength satisfies the regulation requirement. The cold and hot function test results shows the sealing effect is good, and the design requirement is satisfied. (authors)

An on-line estimation of battery pack parameters and state-of-charge using dual filters based on pack model

International Nuclear Information System (INIS)

Zhang, Xu; Wang, Yujie; Yang, Duo; Chen, Zonghai

2016-01-01

Accurate estimation of battery pack state-of-charge plays a very important role for electric vehicles, which directly reflects the behavior of battery pack usage. However, the inconsistency of battery makes the estimation of battery pack state-of-charge different from single cell. In this paper, to estimate the battery pack state-of-charge on-line, the definition of battery pack is proposed, and the relationship between the total available capacity of battery pack and single cell is put forward to analyze the energy efficiency influenced by battery inconsistency, then a lumped parameter battery model is built up to describe the dynamic behavior of battery pack. Furthermore, the extend Kalman filter-unscented Kalman filter algorithm is developed to identify the parameters of battery pack and forecast state-of-charge concurrently. The extend Kalman filter is applied to update the battery pack parameters by real-time measured data, while the unscented Kalman filter is employed to estimate the battery pack state-of-charge. Finally, the proposed approach is verified by experiments operated on the lithium-ion battery under constant current condition and the dynamic stress test profiles. Experimental results indicate that the proposed method can estimate the battery pack state-of-charge with high accuracy. - Highlights: • A novel space state equation is built to describe the pack dynamic behavior. • The dual filters method is used to estimate the pack state-of-charge. • Battery inconsistency is considered to analyze the pack usage efficiency. • The accuracy of the proposed method is verified under different conditions.

Modeling Stone Columns.

Science.gov (United States)

Castro, Jorge

2017-07-11

This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.

Determination of asphaltenes in heavy oils using an on-column method

Energy Technology Data Exchange (ETDEWEB)

Rogel, E.; Ovalles, C.; Moir, M. [Chevron Energy Technology Co., Richmond, CA (United States); Schabron, J.F. [Western Research Inst., Laramie, WY (United States)

2009-07-01

An improved analytical method for determining the asphaltene content in crude oil and petroleum samples was presented. The method used an on-column precipitation technique coupled with an evaporative light scattering detector (ELSD). The column has an inert packing material where the asphaltene was precipitated and re-dissolved using a solvent. Heavy crude oils with asphaltene contents ranging from 5 to 25 per cent w/w were tested. A blend of 90:10 dichloromethane and methanol was used to decrease the influence of hydrocarbon adsorption mechanisms from the polymeric liquid chromatographic phases. A series of laboratory experiments were conducted to compare results obtained using the method with results obtained using traditional gravimetric methods. Regression analysis was used to determine the calibration constants. The study showed that the method can be used as replacement for conventional gravimetric methods when faster results are needed or when sample sizes are small. It was concluded that the method was able to accurately quantify asphaltene contents as low as 120 ppm. 8 refs., 1 tab., 3 figs.

Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

Science.gov (United States)

Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

2009-02-01

Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

Packing Degenerate Graphs Greedily

Czech Academy of Sciences Publication Activity Database

Allen, P.; Böttcher, J.; Hladký, J.; Piguet, Diana

2017-01-01

Roč. 61, August (2017), s. 45-51 ISSN 1571-0653 R&D Projects: GA ČR GJ16-07822Y Institutional support: RVO:67985807 Keywords : tree packing conjecture * graph packing * graph processes Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics

Process engineering and optimization of glycerol separation in a packed-bed reactor for enzymatic biodiesel production.

Science.gov (United States)

Hama, Shinji; Tamalampudi, Sriappareddy; Yoshida, Ayumi; Tamadani, Naoki; Kuratani, Nobuyuki; Noda, Hideo; Fukuda, Hideki; Kondo, Akihiko

2011-11-01

A process model for efficient glycerol separation during methanolysis in an enzymatic packed-bed reactor (PBR) was developed. A theoretical glycerol removal efficiency from the reaction mixture containing over 30% methyl esters was achieved at a high flow rate of 540 ml/h. To facilitate a stable operation of the PBR system, a batch reaction prior to continuous methanolysis was conducted using oils with different acid values and immobilized lipases pretreated with methyl esters. The reaction system successfully attained the methyl ester content of over 30% along with reduced viscosity and water content. Furthermore, to obtain a high methyl ester content above 96% continuously, long-term lipase stability was confirmed by operating a bench-scale PBR system for 550 h, in which the intermediates containing methyl esters and residual glycerides were fed into the enzyme-packed columns connected in series. Therefore, the developed process model is considered useful for industrial biodiesel production. Copyright © 2011 Elsevier Ltd. All rights reserved.

Heuristics for Multidimensional Packing Problems

DEFF Research Database (Denmark)

Egeblad, Jens

for a minimum height container required for the items. The main contributions of the thesis are three new heuristics for strip-packing and knapsack packing problems where items are both rectangular and irregular. In the two first papers we describe a heuristic for the multidimensional strip-packing problem...... that is based on a relaxed placement principle. The heuristic starts with a random overlapping placement of items and large container dimensions. From the overlapping placement overlap is reduced iteratively until a non-overlapping placement is found and a new problem is solved with a smaller container size...... of this heuristic are among the best published in the literature both for two- and three-dimensional strip-packing problems for irregular shapes. In the third paper, we introduce a heuristic for two- and three-dimensional rectangular knapsack packing problems. The two-dimensional heuristic uses the sequence pair...

Valve-stem-packing improvement study. Final report

International Nuclear Information System (INIS)

Adey, C.W.; Klein, J.J.

1982-08-01

By employing questionnaires and face-to-face interviews with valve and valve packing manufacturers, as well as nuclear plant personnel, an understanding of valve stem packing leakage problems from each of the three viewpoints was developed. This information, in-house experience, and available technical literature were used to develop specific recommendations for valve manufacturers, valve packing manufacturers, and nuclear plant valve users. It was generally recommended that each these groups make better use of graphite packing. The questionnaires and interviews indicated that increased usage of graphite packing over the last few years has reduced the incidence of valve packing problems. To confirm this, a survey of Licensee Event Reports (LERs) from 1972 to 1980 was undertaken using the keywords Valve and Packing. A statistical analysis of the LER data confirms that the adoption of graphite packing has significantly reduced valve stem leakage

Enantioselective separation of dansyl-DL-amino acids and some racemates on "click" functionalized native α-cyclodextrin based sub-2 μm columns.

Science.gov (United States)

Ai, Feng; Wang, Yong; Chen, Hui; Yang, Yanhui; Tan, Timothy Thatt Yang; Ng, Siu-Choon

2013-04-21

The current work demonstrates that native α-cyclodextrin, anchored onto sub-2 μm silica particles via "click" reactions and packed into a 5 cm column, was found to be effective for the resolution of 11 pairs of dansyl-DL-amino acids (DAAs) using ultra-high performance liquid chromatography (UHPLC). All DAAs were completely or partially separated on the column and the resolution achieved for 7 pairs of DAAs was significantly greater than 1.5. It was found that the buffer type exerted a profound impact on the separation. The effects of analyte substituents adjacent to the chiral center of analytes as well as operation conditions with respect to the separation efficiency were discussed. Five racemic compounds with single or double rings also got resolved on this short α-CD column to some extent.

Complications of balloon packing in epistaxis

NARCIS (Netherlands)

Vermeeren, Lenka; Derks, Wynia; Fokkens, Wytske; Menger, Dirk Jan

2015-01-01

Although balloon packing appears to be efficient to control epistaxis, severe local complications can occur. We describe four patients with local lesions after balloon packing. Prolonged balloon packing can cause damage to nasal mucosa, septum and alar skin (nasal mucosa, the cartilaginous skeleton

Hypostatic jammed packings of frictionless nonspherical particles

Science.gov (United States)

VanderWerf, Kyle; Jin, Weiwei; Shattuck, Mark D.; O'Hern, Corey S.

2018-01-01

We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, dumbbells, and others to determine which shapes form packings with fewer contacts than degrees of freedom (hypostatic packings) and which have equal numbers of contacts and degrees of freedom (isostatic packings), and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from naive constraint counting. To generate highly accurate force- and torque-balanced packings of circulo-lines and cir-polygons, we developed an interparticle potential that gives continuous forces and torques as a function of the particle coordinates. We show that the packing fraction and coordination number at jamming onset obey a masterlike form for all of the nonspherical particle packings we studied when plotted versus the particle asphericity A , which is proportional to the ratio of the squared perimeter to the area of the particle. Further, the eigenvalue spectra of the dynamical matrix for packings of different particle shapes collapse when plotted at the same A . For hypostatic packings of nonspherical particles, we verify that the number of "quartic" modes along which the potential energy increases as the fourth power of the perturbation amplitude matches the number of missing contacts relative to the isostatic value. We show that the fourth derivatives of the total potential energy in the directions of the quartic modes remain nonzero as the pressure of the packings is decreased to zero. In addition, we calculate the principal curvatures of the inequality constraints for each contact in circulo-line packings and identify specific types of contacts with inequality constraints that possess convex curvature. These contacts can constrain multiple degrees of freedom and allow hypostatic packings of nonspherical particles to be mechanically

Assembly for connecting the column ends of two capillary columns

International Nuclear Information System (INIS)

Kolb, B.; Auer, M.; Pospisil, P.

1984-01-01

In gas chromatography, the column ends of two capillary columns are inserted into a straight capillary from both sides forming annular gaps. The capillary is located in a tee out of which the capillary columns are sealingly guided, and to which carrier gas is supplied by means of a flushing flow conduit. A ''straight-forward operation'' having capillary columns connected in series and a ''flush-back operation'' are possible. The dead volume between the capillary columns can be kept small

High Efficiency Robust Open Tubular Capillary Electrochromatography Column for the Separation of Peptides

Energy Technology Data Exchange (ETDEWEB)

Ali, Faiz; Cheong, Won Jo [Inha University, Incheon (Korea, Republic of)

2016-08-15

In this study, the carefully designed tri-component copolymer layer was fabricated onto the inner surface of a pretreated silica capillary (52 cm effective length, 50 μm id). The initiator moieties were incorporated onto the capillary inner surface by reaction with 4-chloromehtylphenyl isocyanate followed by sodium diethyl dithiocarbamate. Next, RAFT copolymerization was held upon the initiator moieties and a thin polymer film was made. The observed peak capacity was, of course, lower than those of the state-of-the art gradient HPLC systems. The UPLC system operated in the long gradient elution mode with a long narrow column of sub-3 μm packed particles could achieve the impressive high peak capacity of ca. 1000. On the other hand, a system with a 20 cm column of 0.8 μm particles could achieve a peak capacity of 220 (comparable to our result) under a pressure of 20 000 psi in a gradient time of 20 min. It should be noted that the operational conditions of this study has been optimized to obtain the best column separation efficiency. It was also operated in the isocratic elution mode. A better peak capacity is expected if the operational conditions are tuned to the optimum peak capacity.

Coupling sequential injection on-line preconcentration using a PTFE beads packed column to direct injection nebulization inductively coupled plasma mass spectrometry

DEFF Research Database (Denmark)

Wang, Jianhua; Hansen, Elo Harald

2002-01-01

An automated sequential injection on-line preconcentration procedure for trace metals by using a PTFE bead-packed microcolumn coupled to ICP-MS is described, and used for simultaneous analyses of cadmium and lead. In dilute nitric acid (0.5%, v/v), neutral complexes between the analytes...

Ion mobility based on column leaching of South African gold tailings dam with chemometric evaluation.

Science.gov (United States)

Cukrowska, Ewa M; Govender, Koovila; Viljoen, Morris

2004-07-01

New column leaching experiments were designed and used as an alternative rapid screening approach to element mobility assessment. In these experiments, field-moist material was treated with an extracting solution to assess the effects of acidification on element mobility in mine tailings. The main advantage of this version of column leaching experiments with partitioned segments is that they give quick information on current element mobility in conditions closely simulating field conditions to compare with common unrepresentative air-dried, sieved samples used for column leaching experiments. Layers from the tailings dump material were sampled and packed into columns. The design of columns allows extracting leachates from each layer. The extracting solutions used were natural (pH 6.8) and acidified (pH 4.2) rainwater. Metals and anions were determined in the leachates. The concentrations of metals (Ca, Mg, Fe, Mn, Al, Cr, Ni, Co, Zn, and Cu) in sample leachates were determined using ICP OES. The most important anions (NO3-, Cl-, and SO4(2)-) were determined using the closed system izotacophoresis ITP analyser. The chemical analytical data from tailings leaching and physico-chemical data from field measurements (including pH, conductivity, redox potential, temperature) were used for chemometric evaluation of element mobility. Principal factor analysis (PFA) was used to evaluate ions mobility from different layers of tailings dump arising from varied pH and redox conditions. It was found that the results from the partitioned column leaching illustrate much better complex processes of metals mobility from tailings dump than the total column. The chemometric data analysis (PFA) proofed the differences in the various layers leachability that are arising from physico-chemical processes due to chemical composition of tailings dump deposit. Copyright 2004 Elsevier Ltd.

Chemometrics applications in biotechnology processes: predicting column integrity and impurity clearance during reuse of chromatography resin.

Science.gov (United States)

Rathore, Anurag S; Mittal, Shachi; Lute, Scott; Brorson, Kurt

2012-01-01

Separation media, in particular chromatography media, is typically one of the major contributors to the cost of goods for production of a biotechnology therapeutic. To be cost-effective, it is industry practice that media be reused over several cycles before being discarded. The traditional approach for estimating the number of cycles a particular media can be reused for involves performing laboratory scale experiments that monitor column performance and carryover. This dataset is then used to predict the number of cycles the media can be used at manufacturing scale (concurrent validation). Although, well accepted and widely practiced, there are challenges associated with extrapolating the laboratory scale data to manufacturing scale due to differences that may exist across scales. Factors that may be different include: level of impurities in the feed material, lot to lot variability in feedstock impurities, design of the column housing unit with respect to cleanability, and homogeneity of the column packing. In view of these challenges, there is a need for approaches that may be able to predict column underperformance at the manufacturing scale over the product lifecycle. In case such an underperformance is predicted, the operators can unpack and repack the chromatography column beforehand and thus avoid batch loss. Chemometrics offers one such solution. In this article, we present an application of chemometrics toward the analysis of a set of chromatography profiles with the intention of predicting the various events of column underperformance including the backpressure buildup and inefficient deoxyribonucleic acid clearance. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

An on-line coupling of nanofibrous extraction with column-switching high performance liquid chromatography - A case study on the determination of bisphenol A in environmental water samples.

Science.gov (United States)

Háková, Martina; Chocholoušová Havlíková, Lucie; Chvojka, Jiří; Solich, Petr; Šatínský, Dalibor

2018-02-01

Polyamide 6 nanofiber polymers were used as modern sorbents for on-line solid phase extraction (SPE) coupled with liquid chromatography. The on-line SPE system was tested for the determination of bisphenol A in river water samples. Polyamide nanofibers were prepared using needleless electrospinning, inserted into a mini-column cartridge (5 × 4.6mm) and coupled with HPLC. The effect of column packing and the amount of polyamide 6 on extraction efficiency was tested and the packing process was optimized. The proposed method was performed using a 50-µL sample injection followed by an on-line nanofibrous extraction procedure. The influence of the washing mobile phase on the retention of bisphenol A during the extraction procedure was evaluated. Ascentis ® Express C18 (10cm × 4.6mm) core-shell column was used as an analytical column. Fluorescence detection wavelengths (λ ex = 225nm and λ em = 320nm) were used for identification and quantification of Bisphenol A in river waters. The linearity was tested in the range from 2 to 500µgL -1 (using nine calibration points). The limits of detection and quantification were 0.6 and 2µgL -1 , respectively. The developed method was successfully used for the determination of bisphenol A in various samples of river waters in the Czech Republic (The Ohře, Labe, Nisa, Úpa, and Opava Rivers). Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a leadership resource pack

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

The pack contains notes and presentation material for OSD inspectors to help them prepare for health and safety discussions with senior managers. The successful application of the leadership resource pack depends on an inspector gaining familiarity with the contents of the pack. Flexibility and adaptability were considered crucial factors in developing the contents. The pack is not considered a substitute for an inspector's own experience, knowledge or substitute for prior research. The leadership resource pack is intended as a source of knowledge and good practice that demonstrates how positive leadership can drive a health and safety agenda alongside business considerations. The benefits of the leadership resource pack include: the creation of a flexible tool that inspectors can use to highlight key leadership messages in health and safety; the development of a seven-stage model for characterising senior management commitment; practical examples of how leadership in health and safety management was felt throughout nine organisations; ideas for devising an aide memoire for specific discussions with senior managers. (author)

Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters

Science.gov (United States)

Hinkle, S.R.; Böhlke, J.K.; Fisher, L.H.

2008-01-01

Septic tank systems are an important source of NO3- to many aquifers, yet characterization of N mass balance and isotope systematics following septic tank effluent discharge into unsaturated sediments has received limited attention. In this study, samples of septic tank effluent before and after transport through single-pass packed-bed filters (sand filters) were evaluated to elucidate mass balance and isotope effects associated with septic tank effluent discharge to unsaturated sediments. Chemical and isotopic data from five newly installed pairs and ten established pairs of septic tanks and packed-bed filters serving single homes in Oregon indicate that aqueous solute concentrations are affected by variations in recharge (precipitation, evapotranspiration), NH4+ sorption (primarily in immature systems), nitrification, and gaseous N loss via NH3 volatilization and(or) N2 or N2O release during nitrification/denitrification. Substantial NH4+ sorption capacity was also observed in laboratory columns with synthetic effluent. Septic tank effluent ??15N-NH4+ values were almost constant and averaged + 4.9??? ?? 0.4??? (1 ??). In contrast, ??15N values of NO3- leaving mature packed-bed filters were variable (+ 0.8 to + 14.4???) and averaged + 7.2??? ?? 2.6???. Net N loss in the two networks of packed-bed filters was indicated by average 10-30% decreases in Cl--normalized N concentrations and 2-3??? increases in ??15N, consistent with fractionation accompanying gaseous N losses and corroborating established links between septic tank effluent and NO3- in a local, shallow aquifer. Values of ??18O-NO3- leaving mature packed-bed filters ranged from - 10.2 to - 2.3??? (mean - 6.4??? ?? 1.8???), and were intermediate between a 2/3 H2O-O + 1/3 O2-O conceptualization and a 100% H2O-O conceptualization of ??18O-NO3- generation during nitrification.

Mechanised packing for longwall coal faces. Monolithic packing and powered supports for the packhole

Energy Technology Data Exchange (ETDEWEB)

Carr, F; Kitching, F

1978-11-01

If full advantage is to be taken of the great advances that have taken place in power loading and powered support at the coalface, other operations in that vicinity must be similarly mechanised and automated. The gateside packing is one of the most important of these ancillary operations on the longwall face, and in previous articles F. Carr and F. Kitching, National Coal Board Headquarters, Coalface Operations Mining Engineers have given a very comprehensive resume of the present situation. Subjects covered include the requirements of mechanised packing, the parameters involved, the various working arrangements, the different systems of gate-ends, the types of equipment that are being used, their characteristics, the spread of their application, and the results obtained from them. In this article the authors conclude their survey by dealing with dirt/cement and anhydrite packing, by taking a hard look at powered supports for the packhole, and by expressing their views on the way mechanised packing may be expected to develop in the future.

Hypostatic jammed packings of frictionless nonspherical particles

OpenAIRE

VanderWerf, Kyle; Jin, Weiwei; Shattuck, Mark D.; O'Hern, Corey S.

2017-01-01

We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, and dumbbells to determine which shapes form hypostatic versus isostatic packings and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from na\\"ive constraint counting. To generate highly accurate force- and torque-balanced packings of circul...

Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.

Science.gov (United States)

Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J

2015-05-22

Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.

Packed bed reactor for degradation of simulated cyanide-containing wastewater.

Science.gov (United States)

Kumar, Virender; Kumar, Vijay; Bhalla, Tek Chand

2015-10-01

The discharge of cyanide-containing effluents into the environment contaminates water bodies and soil. Effective methods of treatment which can detoxify cyanide are the need of the hour. The aim of the present study is to develop a bioreactor for complete degradation of cyanide using immobilized cells of Serratia marcescens RL2b. Alginate-entrapped cells of S. marcescens RL2b were used for complete degradation of cyanide in a packed bed reactor (PBR). Cells grown in minimal salt medium (pH 6.0) were harvested after 20 h and exhibited 0.4 U mg -1  dcw activity and 99 % cyanide degradation in 10 h. These resting cells were entrapped using 3 % alginate beads and packed in a column reactor (20 × 1.7 cm). Simulated cyanide (12 mmol l -1 )-containing wastewater was loaded and fractions were collected after different time intervals at various flow rates. Complete degradation of 12 m mmol l -1 (780 mg l -1 ) cyanide in 10 h was observed at a flow rate of 1.5 ml h -1 . The degradation of cyanide in PBR showed direct dependence on retention time. The retention time of cyanide in the reactor was 9.27 h. The PBR can degrade 1.2 g of cyanide completely in 1 day.

JCE Feature Columns

Science.gov (United States)

Holmes, Jon L.

1999-05-01

The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

Development of an effective valve packing program

Energy Technology Data Exchange (ETDEWEB)

Hart, K.A.

1996-12-01

Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

Simple, specific analysis of organophosphorus and carbamate pesticides in sediments using column extraction and gas chromatography

Science.gov (United States)

Belisle, A.A.; Swineford, D.M.

1988-01-01

A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetone:methylene chloride (1:l,v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93 % for sediments extracted shortly after spiking, but decreased significantly as the samples aged.

Random packing of digitized particles

NARCIS (Netherlands)

Korte, de A.C.J.; Brouwers, H.J.H.

2013-01-01

The random packing of regularly and irregularly shaped particles has been studied extensively. Within this paper, packing is studied from the perspective of digitized particles. These digitized particles are developed for and used in cellular automata systems, which are employed for the simple

Random packing of digitized particles

NARCIS (Netherlands)

de Korte, A.C.J.; Brouwers, Jos

2012-01-01

The random packing of regularly and irregularly shaped particles has been studied extensively. Within this paper, packing is studied from the perspective of digitized particles. These digitized particles are developed for and used in cellular automata systems, which are employed for the simple

BNGS B valve packing program

International Nuclear Information System (INIS)

Cumming, D.

1995-01-01

The Bruce B Valve Packing Program began in 1987. The early history and development were presented at the 1992 International CANDU Maintenance conference. This presentation covers the evolution of the Bruce B Valve Packing Program over the period 1992 to 1995. (author)

The pursuit of perfect packing

CERN Document Server

Weaire, Denis

2008-01-01

Coauthored by one of the creators of the most efficient space packing solution, the Weaire-Phelan structure, The Pursuit of Perfect Packing, Second Edition explores a problem of importance in physics, mathematics, chemistry, biology, and engineering: the packing of structures. Maintaining its mathematical core, this edition continues and revises some of the stories from its predecessor while adding several new examples and applications. The book focuses on both scientific and everyday problems ranging from atoms to honeycombs. It describes packing models, such as the Kepler conjecture, Voronoï decomposition, and Delaunay decomposition, as well as actual structure models, such as the Kelvin cell and the Weaire-Phelan structure. The authors discuss numerous historical aspects and provide biographical details on influential contributors to the field, including emails from Thomas Hales and Ken Brakke. With examples from physics, crystallography, engineering, and biology, this accessible and whimsical bo...

Column studies of strontium and cesium migration in a granular geologic material

International Nuclear Information System (INIS)

Reynolds, W.D.; Gilham, R.W.; Cherry, J.A.

1981-06-01

Infinite-pulse, miscible-displacement experiments were conducted to investigate the applicability of batch Ksub(d) values in the prediction of reactive solute transport during dynamic flow through porous media. Non-reactive tracers (chloride, tritium and oxygen-18), and the reactive tracers (strontium-85 and cesium-137) were passed through a column 5.0 cm long and 6.5 cm in diameter packed with a medium to fine sand. The effluent concentrations of the nonreactive solutes were accurately predicted using the advection-dispersion equation; however, there were large discrepancies between the measured and predicted effluent concentrations for both reactive species. Good agreement was obtained between the measured and computed results by incorporating an empirical isotherm into the advection-dispersion model

Battery Pack Thermal Design

Energy Technology Data Exchange (ETDEWEB)

Pesaran, Ahmad

2016-06-14

This presentation describes the thermal design of battery packs at the National Renewable Energy Laboratory. A battery thermal management system essential for xEVs for both normal operation during daily driving (achieving life and performance) and off-normal operation during abuse conditions (achieving safety). The battery thermal management system needs to be optimized with the right tools for the lowest cost. Experimental tools such as NREL's isothermal battery calorimeter, thermal imaging, and heat transfer setups are needed. Thermal models and computer-aided engineering tools are useful for robust designs. During abuse conditions, designs should prevent cell-to-cell propagation in a module/pack (i.e., keep the fire small and manageable). NREL's battery ISC device can be used for evaluating the robustness of a module/pack to cell-to-cell propagation.

7 CFR 982.11 - Pack.

Science.gov (United States)

2010-01-01

... according to size, internal quality, and external appearance and condition of hazelnuts packed in accordance... 7 Agriculture 8 2010-01-01 2010-01-01 false Pack. 982.11 Section 982.11 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and...

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

International Nuclear Information System (INIS)

Nguyen, T.A.H.; Ngo, H.H.; Guo, W.S.; Pham, T.Q.; Li, F.M.; Nguyen, T.V.; Bui, X.T.

2015-01-01

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

Energy Technology Data Exchange (ETDEWEB)

Nguyen, T.A.H. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Ngo, H.H., E-mail: ngohuuhao121@gmail.com [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Guo, W.S. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Pham, T.Q. [Faculty of Geography, University of Science, Vietnam National University, Hanoi (Viet Nam); Li, F.M. [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Nguyen, T.V. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Bui, X.T. [Environmental Engineering and Management Research Group, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Environment and Natural Resources, Ho Chi Minh City University of Technology-Vietnam National University, Ho Chi Minh City (Viet Nam)

2015-08-01

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage.

Deterministic indexing for packed strings

DEFF Research Database (Denmark)

Bille, Philip; Gørtz, Inge Li; Skjoldjensen, Frederik Rye

2017-01-01

Given a string S of length n, the classic string indexing problem is to preprocess S into a compact data structure that supports efficient subsequent pattern queries. In the deterministic variant the goal is to solve the string indexing problem without any randomization (at preprocessing time...... or query time). In the packed variant the strings are stored with several character in a single word, giving us the opportunity to read multiple characters simultaneously. Our main result is a new string index in the deterministic and packed setting. Given a packed string S of length n over an alphabet σ...

Post-column derivatization capillary electrochromatography for detection of biogenic amines in tuna-meat.

Science.gov (United States)

Oguri, Shigeyuki; Okuya, Yukie; Yanase, Yukiko; Suzuki, Sayaka

2008-08-15

A system to perform post-column derivatization capillary electrochromatography (CEC) was developed for the first time. The system mainly included a 4-microm (O.D.) silica packed column (200 mm effective length x 0.1 mm inner diameter I.D.) with micro-magnetic particles (MMPs) frits, a T-junction connector, an in-line fluorescence detector and a high-voltage power supply. The system was evaluated by using histamine (HA) as a standard biogenic amine for this study. A 5 microM HA solution was loaded at the anodic site of the capillary column by applying 3 kV for 5s. Then, HA was electrophoretically eluted with a 20mM phosphate buffer (pH 7) by applying 3 kV, and was derivatized with 3mM o-phthalaldehyde (OPA)/N-acetylcysteine (NAC) in 100 mM borate (pH 10), which was continuously delivered through the reagent-loading capillary tube by gravity into the T-junction connector. HA derivative was finally detected with the in-line fluorescence detector (lambda(Ex)=340 nm, lambda(Em)=450 nm) at 9.7 min after sample loading. To test the utility of this system, it was next employed for its ability to detect the presence of HA and other kinds of biogenic amines, including cadaverine (Cad), spermidine (Spm) and tyramine (Tyr) in tuna-meat, once the validity of the method had been confirmed.

Random packing of colloids and granular matter

NARCIS (Netherlands)

Wouterse, A.

2008-01-01

This thesis deals with the random packing of colloids and granular matter. A random packing is a stable disordered collection of touching particles, without long-range positional and orientational order. Experimental random packings of particles with the same shape but made of different materials

Packing circles and spheres on surfaces

KAUST Repository

Schiftner, Alexander; Hö binger, Mathias; Wallner, Johannes; Pottmann, Helmut

2009-01-01

Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

Packing circles and spheres on surfaces

KAUST Repository

Schiftner, Alexander

2009-12-01

Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

Packing circles and spheres on surfaces

KAUST Repository

Schiftner, Alexander

2009-01-01

Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

Packing circles and spheres on surfaces

KAUST Repository

Schiftner, Alexander; Hö binger, Mathias; Wallner, Johannes; Pottmann, Helmut

2009-01-01

Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

Continuous adsorption of Pb(II) and methylene blue by engineered graphite oxide coated sand in fixed-bed column

Energy Technology Data Exchange (ETDEWEB)

Gong, Ji-Lai, E-mail: jilaigong@gmail.com [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zhang, Yong-Liang; Jiang, Yan [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zeng, Guang-Ming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Cui, Zhi-Hui; Liu, Ke; Deng, Can-Hui; Niu, Qiu-Ya; Deng, Jiu-Hua [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Huan, Shuang-Yan [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2015-03-01

Highlights: • GO-sand was prepared by coating GO on the surface of sand. • Pb(II) and MB were efficiently removed by GO-sand filter in column. • The removal of MB was enhanced with the presence of Pb(II). • GO-sand is low-cost and convenient for its application as packed bed filter. - Abstract: The mixture of several effluents, caused by the improper handling and management of effluents, generated multi-component wastewater containing both metals and dyes, leading to the complicated treatment process. In this study, a continuous adsorption of Pb(II) and methylene blue (MB) has been studied in single and binary solutions by using graphite oxide coated sand (GO-sand) as an adsorbent in a fixed-bed column. GO-sand was analyzed by X-ray photoelectron spectroscopy before and after analyte adsorption. Compared with sand filter, adsorption quantity and capacity for Pb(II) and MB by GO-sand filter were greatly increased. In Pb(II) and MB single solutions, the experimental parameters were investigated in detail including initial concentration, flow rate, bed depth and pH. Exhaustion time decreased with increasing initial concentration and flow rate, and increased with increasing bed depth and pH. In the Pb(II)-MB binary solution, exhaustion time significantly decreased for Pb(II) adsorption, but increased for MB adsorption. The reason was explained that the more favorable adsorption for MB onto the surface of GO-sand than that for Pb(II), which was derived from π–π interaction between MB and GO on sand surface in packed filter. The Yoon–Nelson model was applied at different concentration of Pb(II) and MB to predict the breakthrough curves. The experimental data were well fit with the model indicating that it was suitable for this column design.

Packing configuration performance for small stem diameters

International Nuclear Information System (INIS)

Aikin, J.A.; Spence, C.G.; Cumming, D.

1997-01-01

The extensive use of graphite packing and its excellent track record for large isolating valves in CANDU, Primary Heat Transfer (PHT) systems has resulted in an increased application of graphite packing on the conventional side. Many of these applications are in air operated valves (AOVs) where the packing sets are used on small stem diameters (<1 inch) with frequent short-cycling strokes (± 10% of full stroke). The direct application of the proven packing configurations for large isolated valves to control valve application has generated problems such as stiction, packing wear and, in isolated cases, stem stall. To address this issue, a test program was conducted at AECL, CRL by MED branch. The testing showed that by reconfiguring the packing sets and using PTFE wafers reductions in stem friction of 50% at ambient conditions, a 3 fold at hot conditions are achievable. The test program also demonstrated benefits gained in packing wear with different stem roughness finishes and the potential need to exercise small stems valves that see less than full stroke cycling. The paper describes the tests results and provides field support experience. (author)

Bidispersed Sphere Packing on Spherical Surfaces

Science.gov (United States)

Atherton, Timothy; Mascioli, Andrew; Burke, Christopher

Packing problems on spherical surfaces have a long history, originating in the classic Thompson problem of finding the ground state configuration of charges on a sphere. Such packings contain a minimal number of defects needed to accommodate the curvature; this is predictable using the Gauss-Bonnet theorem from knowledge of the topology of the surface and the local symmetry of the ordering. Famously, the packing of spherical particles on a sphere contains a 'scar' transition, where additional defects over those required by topology appear above a certain critical number of particles and self-organize into chains or scars. In this work, we study the packing of bidispersed packings on a sphere, and hence determine the interaction of bidispersity and curvature. The resultant configurations are nearly crystalline for low values of bidispersity and retain scar-like structures; these rapidly become disordered for intermediate values and approach a so-called Appollonian limit at the point where smaller particles can be entirely accommodated within the voids left by the larger particles. We connect our results with studies of bidispersed packings in the bulk and on flat surfaces from the literature on glassy systems and jamming. Supported by a Cottrell Award from the Research Corporation for Science Advancement.

Non-equilibrium mass transfer absorption model for the design of boron isotopes chemical exchange column

International Nuclear Information System (INIS)

Bai, Peng; Fan, Kaigong; Guo, Xianghai; Zhang, Haocui

2016-01-01

Highlights: • We propose a non-equilibrium mass transfer absorption model instead of a distillation equilibrium model to calculate boron isotopes separation. • We apply the model to calculate the needed column height to meet prescribed separation requirements. - Abstract: To interpret the phenomenon of chemical exchange in boron isotopes separation accurately, the process is specified as an absorption–reaction–desorption hybrid process instead of a distillation equilibrium model, the non-equilibrium mass transfer absorption model is put forward and a mass transfer enhancement factor E is introduced to find the packing height needed to meet the specified separation requirements with MATLAB.

Column Liquid Chromatography.

Science.gov (United States)

Majors, Ronald E.; And Others

1984-01-01

Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

Influence of γ-ray radiation on mechanical character of packing

International Nuclear Information System (INIS)

Tashiro, Hisao; Sakuma, Toshio

1989-01-01

This paper describes the results of investigation on coefficient of friction, normal to axial pressure-ratio and compressed strain of packings influenced by γ-ray irradiation, which are necessary to evaluate the mechanical characteristics of packing, using packings made of seven kinds of new materials and conventional asbestos packing A. It resulted that graphite packing was less influenced by the γ-ray exposure, whereas carbon-fiber (pitch) packing, tefron-fiber packing and alamid-fiber packing were much influenced as compared with the graphite packing. (author)

Caffeine degradation by Rhizopus delemar in packed bed column bioreactor using coffee husk as substrate Degradação de cafeína por Rhizopus delemar em biorreator de colunas usando casca de café como substrato

Directory of Open Access Journals (Sweden)

Cristiane Vanessa Tagliari

2003-11-01

Full Text Available Various microorganisms including bacteria, yeast and fungi can degrade caffeine. There are few publications about caffeine degradation pathway in filamentous fungi, mainly by solid-state fermentation (SSF. Studies were carried out on degradation of caffeine and their metabolites by filamentous fungi in SSF using coffee husk as substrate. The purpose of this work was to investigate the caffeine degradation pathway by Rhizopus delemar in packed bed column fermenter and to compare this degradation metabolism with glass flasks fermentation. The methylxanthines were quantified by HPLC analysis. The experiments were realized with the optimized conditions in previous experiments: pH 6.5, 28ºC, inoculation rate 10(6 spores/g substrate, aeration rate 60 mL/min and initial moisture 73%. Under these conditions, after 72 hous of fermentation was achieved only 0.19% of caffeine and 0.014% of theophylline in the coffee husk. The strain proved to be able for caffeine and theophylline degradation by SSF in packed bed column bioreactor.Diversos microrganismos incluindo bactérias, fungos e leveduras são capazes de assimilar a cafeína de meios sintéticos ou de resíduos de café. Existem poucos trabalhos sobre a via de degradação da cafeína em fungos filamentosos, principalmente por fermentação no estado sólido (FES. Estudos de degradação da cafeína por fungos filamentosos em FES usando casca de café como substrato vêm sendo realizados. O objetivo deste trabalho foi investigar a via de degradação da cafeína por Rhizopus delemar em biorreator de colunas aeradas e comparar este metabolismo de degradação com o da fermentação em frascos de vidro. As metilxantinas foram quantificadas por análises em HPLC. Os experimentos foram realizados com as condições otimizadas previamente: pH 6,5, 28ºC, 10(6 espores/g substrato, vazão de ar 60 mL/min e 73% de umidade inicial. Após 90 horas de fermentação, 65% da cafeína foi reduzida, resultando 0

Quasi-human seniority-order algorithm for unequal circles packing

International Nuclear Information System (INIS)

Zhu, Dingju

2016-01-01

In the existing methods for solving unequal circles packing problems, the initial configuration is given arbitrarily or randomly, but the impact of different initial configurations for existing packing algorithm to the speed of existing packing algorithm solving unequal circles packing problems is very large. The quasi-human seniority-order algorithm proposed in this paper can generate a better initial configuration for existing packing algorithm to accelerate the speed of existing packing algorithm solving unequal circles packing problems. In experiments, the quasi-human seniority-order algorithm is applied to generate better initial configurations for quasi-physical elasticity methods to solve the unequal circles packing problems, and the experimental results show that the proposed quasi-human seniority-order algorithm can greatly improve the speed of solving the problem.

48 CFR 552.211-87 - Export packing.

Science.gov (United States)

2010-10-01

... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Export packing. 552.211-87... FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Text of Provisions and Clauses 552.211-87 Export packing. As prescribed in 511.204(b)(7), insert the following clause: Export Packing (JAN 2010) (a...

High-resolution ultrahigh-pressure long column reversed-phase liquid chromatography for top-down proteomics

Energy Technology Data Exchange (ETDEWEB)

Shen, Yufeng; Tolic, Nikola; Piehowski, Paul D.; Shukla, Anil K.; Kim, Sangtae; Zhao, Rui; Qu, Yi; Robinson, E. W.; Smith, Richard D.; Pasa-Tolic, Ljiljana

2017-05-01

We report development of an approach providing high-resolution RPLC of proteins and its utility for mass spectrometry-based top-down proteomics. A chromatographic peak capacity of ~450 was achieved for proteins and large polypeptides having MWs up to 43 kDa in the context of proteomics applications. RPLC column lengths from 20 to 200 cm, particle sizes from 1.5 to 5 m, bonding alkyl chains from C1 to C2, C4, C8, and C18, and particle surface structures that spanned porous, superficially porous (porous shell, core-shell), and nonporous were investigated at pressures up to14K psi. Column length was found as the most important factor for >20 kDa proteins in gradient RPLC, and shortening column length degraded RPLC resolution and sensitivity regardless of the size and surface structure of the packing particles used. The alkyl chains bonded to the silica particle surface significantly affected the RPLC recovery and efficiency, and short alkyl C1-C4 phases provided higher sensitivity and resolution than C8 and C18 phases. Long gradient separations (e.g., >10 hours) with long columns (e.g., 100 cm) were particularly effective in conjunction with use of high accuracy mass spectrometers (e.g., the Orbitrap Elite) for top-down proteomics with improved proteoform coverage by allowing multiple HCD, CID, and ETD dissociation modes. It was also found that HCD produced small fragments useful for proteoform identification, while low energy CID and ETD often complemented HCD by providing large fragments.

Shelving 6 pack crisps

OpenAIRE

Garriga Torrecillas, Núria; Otrubova, Natalie; Worm, Robert; Larroque, Thibaut

2017-01-01

6-Pack crisps are one of the main products sold by PepsiCo using the standard shelf storage options offered by Tesco PLC. While presenting specific packaging involves a multitude of variables. This report focusses on cognitive recognition, brand confusion and product attractiveness. PepsiCo asked the research team to investigate innovative ways of presenting the crisp 6-pack variant on instore displays. research shows that attraction is crucial in the form of expected rewards. The combination...

Does Post Septoplasty Nasal Packing Reduce Complications?

Directory of Open Access Journals (Sweden)

Bijan Naghibzadeh

2011-01-01

Full Text Available The main issues in nasal surgery are to stabilize the nose in the good position after surgery and preserve the cartilages and bones in the favorable situation and reduce the risk of deviation recurrence. Also it is necessary to avoid the synechia formation, nasal valve narrowing, hematoma and bleeding. Due to the above mentioned problems and in order to solve and minimize them nasal packing, nasal splint and nasal mold have been advised. Patients for whom the nasal packing used may faced to some problems like naso-pulmonary reflex, intractable pain, sleep disorder, post operation infection and very dangerous complication like toxic shock syndrome. We have two groups of patients and three surgeons (one of the surgeons used post operative nasal packing in his patients and the two others surgeons did not.Complications and morbidities were compared in these two groups. Comparing the two groups showed that the rate of complication and morbidities between these two groups were same and the differences were not valuable, except the pain and discomfort post operatively and at the time of its removal. Nasal packing has several risks for the patients while its effects are not studied. Septoplasty can be safely performed without postoperative nasal packing. Nasal packing had no main findings that compensated its usage. Septal suture is one of the procedures that can be used as alternative method to nasal packing. Therefore the nasal packing after septoplasty should be reserved for the patients with increased risk of bleeding.

To compare efficacy & discomfort in posterior nasal packing with foley's catheters versus bipp gauze packing in cases of posterior epistaxis

International Nuclear Information System (INIS)

Khan, M.A.; Ahmed, A.

2015-01-01

To compare efficacy and discomfort in posterior nasal packing with Foley's catheters versus BIPP gauze packing in cases of posterior epistaxis. Study Design: Randomized controlled trial. Place and Duration of Study: Combined Military Hospital (CMH) Kharian from October 2011 to October 2013. Material and Methods: A total of 206 patients of posterior epistaxis were included in the study through non-probability convenience sampling and randomly divided in two groups of 103 each. In group A patients were treated by posterior nasal packing with Foley's catheter and in group B patients were treated by posterior nasal packing with BIPP gauze and results in terms of control of epistaxis and discomfort during pack insertion, while the packs were in situ and pack removal, based on VAS (Visual Analogue Scale) were observed. Results: Average age in group A was 52.64 years (SD=9.57) and in group B it was 50.27 years (SD ± 10.13). There were 71 (68.9%) males in group A while 67 (65%) males in group B. During posterior nasal pack insertion, the mean pain score in Group A was 6.21 (SD ± I.13) and in Group B was 7.43 (SD ± 1.19). The mean pain score with the pack in situ was 4.27 (SD ± 0.08) in Group A versus 4.76 (SD ± 0.09) Group B. Similarly pack removal was also more painful in group B than group A (6.14 ± 0.91 vs 6.89 ± 1.09) (p =0.000). In the group A, 31 (30.1%) patients had rebleeding after pack removal, out of which 9 (8.7%) had significant bleeding requiring repacking. In 22 (21.4%) cases there was mild bleeding which settled without repacking. In group B 22 (21.4%) patients had rebleeding after pack removal, out of which 5 (4.7%) had significant bleeding requiring repacking. Conclusion: It is concluded that posterior nasal packing with BIPP gauze pack is effective for controlling posterior epistaxis but causes more discomfort to the patients as compared to Foley's catheter packing. (author)

Biodegradation of No. 2 diesel fuel in the vadose zone: A soil column study

International Nuclear Information System (INIS)

Widrig, D.L.; Manning, J.F. Jr.

1995-01-01

Packed soil columns were used to simulate and investigate in situ biological remediation of soil contaminated with diesel fuel. The authors investigated and evaluated several operating strategies, including continuous flooding of the column soil with nutrient solution, and periodic operating cycles consisting of flooding followed by draining and aeration. The objectives were: (a) to determine the extent of diesel fuel degradation in soil columns under four operating conditions (biologically inhibited control; continuous saturation with nitrogen and phosphorus amendments; periodic operation, consisting of flooding with nitrogen and phosphorus, followed by draining and forced aeration; and periodic operation, consisting of flooding with nitrogen phosphorus, and calcium and magnesium amendments, followed by draining and forced aeration); (b) to evaluate CO 2 production and oxygen consumption as indicators of biodegradation; (c) to monitor hydraulic conductivity under different operating strategies; and (d) to examine the system requirements for nitrogen and phosphorus. The results showed that periodic operation promoted higher rates of biodegradation of diesel fuel in soil and minimized the use of water containing nutrient amendments, and consequently the possible need to collect and treat such water. The authors believe that monitoring CO 2 and O 2 levels in situ may provide a means of optimizing the timing of flooding and aeration events to increase degradation rates. Results of this laboratory study will aid in improving the design and operation of field-scale bioremediation systems

A Quantitative Study on Packing Density and Pozzolanic Activity of Cementitious Materials Based on the Compaction Packing Model

International Nuclear Information System (INIS)

Gong, Jianqing; Chou, Kai; Huang, Zheng Yu; Zhao, Minghua

2014-01-01

A brief introduction to the theoretical basis of compaction packing model (CPM) and an over-view of the principle of the specific strength method provided the starting point of this study. Then, research on quantitative relations was carried out to find the correlation between the contribution rate of the pozzolanic activity and the contribution value of packing density when CPM was applied to fine powder mixture systems. The concept of the contribution value of the packing density being in direct correspondence with the contribution rate was proved by the compressive strength results and SEM images. The results indicated that the variation rule of the contribution rate of the pozzolanic activity is similar to that of the contribution value of packing density as calculated by CPM. This means the contribution value of the packing density could approximately simulate the change tendency of the contribution rate of the pozzolanic activity, which is of significant value for the future of mix designs for high and ultra-high performance concrete

Power Packing

Centers for Disease Control (CDC) Podcasts

2011-08-16

In this podcast for kids, the Kidtastics talk about how to pack a lunch safely, to help keep you from getting sick.  Created: 8/16/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/16/2011.

Decontamination of pesticide packing using ionizing radiation

International Nuclear Information System (INIS)

Duarte, C.L.; Mori, M.N.; Kodama, Yasko; Oikawa, H.; Sampa, M.H.O.

2007-01-01

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry-GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases

Decontamination of pesticide packing using ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Duarte, C.L. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)], E-mail: clduarte@ipen.br; Mori, M.N.; Kodama, Yasko; Oikawa, H.; Sampa, M.H.O. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)

2007-11-15

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry-GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.

Flow-through Column Experiments and Modeling of Microbially Mediated Cr(VI) Reduction at Hanford 100H

Science.gov (United States)

Yang, L.; Molins, S.; Beller, H. R.; Brodie, E. L.; Steefel, C.; Nico, P. S.; Han, R.

2010-12-01

Microbially mediated Cr(VI) reduction at the Hanford 100H area was investigated by flow-through column experiments. Three separate experiments were conducted to promote microbial activities associated with denitrification, iron and sulfate reduction, respectively. Replicate columns packed with natural sediments from the site under anaerobic environment were injected with 5mM Lactate as the electron donor and 5 μM Cr(VI) in all experiments. Sulfate and nitrate solutions were added to act as the main electron acceptors in the respective experiments, while iron columns relied on the indigenous sediment iron (and manganese) oxides as electron acceptors. Column effluent solutions were analyzed by IC and ICP-MS to monitor the microbial consumption/conversion of lactate and the associated Cr(VI) reduction. Biogeochemical reactive transport modeling was performed to gain further insights into the reaction mechanisms and Cr(VI) bioreduction rates. All experimental columns showed a reduction of the injected Cr(VI). Columns under denitrifying conditions showed the least Cr(VI) reduction at early stages (simulations indicated that biomass growth completely depleted influent ammonium, and called for an additional source of N to account for the measured reduction rates. Iron columns were the least active with undetectable consumption of the injected lactate, slowest cell growth, and the smallest change in Cr(VI) concentrations during the course of the experiment. In contrast, columns under sulfate-reducing/fermentative conditions exhibited the greatest Cr(VI) reduction capacity. Two sulfate columns evolved to complete lactate fermentation with acetate and propionate produced in the column effluent after 40 days of experiments. These fermenting columns showed a complete removal of injected Cr(VI), visible precipitation of sulfide minerals, and a significant increase in effluent Fe and Mn concentrations. Reactive transport simulations suggested that direct reduction of Cr(VI) by

Structured packing: an opportunity for energy savings

International Nuclear Information System (INIS)

Chavez T, R.H.; Guadarrama G, J.J.

1996-01-01

This work emphasizes the advantages about the use of structured packing. This type of packings allows by its geometry to reduce the processing time giving energy savings and throw down the production costs in several industries such as heavy water production plants, petrochemical industry and all industries involved with separation processes. There is a comparative results of energy consumption utilizing the structured vs. Raschig packings. (Author)

Automated Hydrophobic Interaction Chromatography Column Selection for Use in Protein Purification

Science.gov (United States)

Murphy, Patrick J. M.; Stone, Orrin J.; Anderson, Michelle E.

2011-01-01

In contrast to other chromatographic methods for purifying proteins (e.g. gel filtration, affinity, and ion exchange), hydrophobic interaction chromatography (HIC) commonly requires experimental determination (referred to as screening or "scouting") in order to select the most suitable chromatographic medium for purifying a given protein 1. The method presented here describes an automated approach to scouting for an optimal HIC media to be used in protein purification. HIC separates proteins and other biomolecules from a crude lysate based on differences in hydrophobicity. Similar to affinity chromatography (AC) and ion exchange chromatography (IEX), HIC is capable of concentrating the protein of interest as it progresses through the chromatographic process. Proteins best suited for purification by HIC include those with hydrophobic surface regions and able to withstand exposure to salt concentrations in excess of 2 M ammonium sulfate ((NH4)2SO4). HIC is often chosen as a purification method for proteins lacking an affinity tag, and thus unsuitable for AC, and when IEX fails to provide adequate purification. Hydrophobic moieties on the protein surface temporarily bind to a nonpolar ligand coupled to an inert, immobile matrix. The interaction between protein and ligand are highly dependent on the salt concentration of the buffer flowing through the chromatography column, with high ionic concentrations strengthening the protein-ligand interaction and making the protein immobile (i.e. bound inside the column) 2. As salt concentrations decrease, the protein-ligand interaction dissipates, the protein again becomes mobile and elutes from the column. Several HIC media are commercially available in pre-packed columns, each containing one of several hydrophobic ligands (e.g. S-butyl, butyl, octyl, and phenyl) cross-linked at varying densities to agarose beads of a specific diameter 3. Automated column scouting allows for an efficient approach for determining which HIC media

27 CFR 24.308 - Bottled or packed wine record.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottled or packed wine... BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Records and Reports § 24.308 Bottled or packed wine record. A proprietor who bottles, packs, or receives bottled or packed beverage wine in bond shall...

Hashish Body Packing: A Case Report

Directory of Open Access Journals (Sweden)

Manuel Jesus Soriano-Perez

2009-01-01

Full Text Available A 42-year-old African male was brought by the police to the emergency department under suspicion of drug smuggling by body-packing. Plain abdominal radiograph showed multiple foreign bodies within the gastrointestinal tract. Contrast-enhanced abdominal CT confirmed the findings, and the patient admitted to have swallowed “balls” of hashish. Body-packing is a recognized method of smuggling drugs across international borders. Body packers may present to the emergency department because of drug toxicity, intestinal obstruction, or more commonly, requested by law-enforcement officers for medical confirmation or exclusion of suspected body packing.

36 CFR 34.10 - Saddle and pack animals.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent. ...

CoolPack – Simulation tools for refrigeration systems

DEFF Research Database (Denmark)

Jakobsen, Arne; Rasmussen, Bjarne D.; Andersen, Simon Engedal

1999-01-01

CoolPack is a collection of programs used for energy analysis and optimisation of refrigeration systems. CoolPack is developed at the Department of Energy Engineering at the Technical University of Denmark. The Danish Energy Agency finances the project. CoolPack is freeware and can be downloaded...

Family of columns isospectral to gravity-loaded columns with tip force: A discrete approach

Science.gov (United States)

Ramachandran, Nirmal; Ganguli, Ranjan

2018-06-01

A discrete model is introduced to analyze transverse vibration of straight, clamped-free (CF) columns of variable cross-sectional geometry under the influence of gravity and a constant axial force at the tip. The discrete model is used to determine critical combinations of loading parameters - a gravity parameter and a tip force parameter - that cause onset of dynamic instability in the CF column. A methodology, based on matrix-factorization, is described to transform the discrete model into a family of models corresponding to weightless and unloaded clamped-free (WUCF) columns, each with a transverse vibration spectrum isospectral to the original model. Characteristics of models in this isospectral family are dependent on three transformation parameters. A procedure is discussed to convert the isospectral discrete model description into geometric description of realistic columns i.e. from the discrete model, we construct isospectral WUCF columns with rectangular cross-sections varying in width and depth. As part of numerical studies to demonstrate efficacy of techniques presented, frequency parameters of a uniform column and three types of tapered CF columns under different combinations of loading parameters are obtained from the discrete model. Critical combinations of these parameters for a typical tapered column are derived. These results match with published results. Example CF columns, under arbitrarily-chosen combinations of loading parameters are considered and for each combination, isospectral WUCF columns are constructed. Role of transformation parameters in determining characteristics of isospectral columns is discussed and optimum values are deduced. Natural frequencies of these WUCF columns computed using Finite Element Method (FEM) match well with those of the given gravity-loaded CF column with tip force, hence confirming isospectrality.

Simulation of abuse tolerance of lithium-ion battery packs

Energy Technology Data Exchange (ETDEWEB)

Spotnitz, Robert M.; Weaver, James; Yeduvaka, Gowri [Battery Design LLC, 2277 DeLucchi Drive, Pleasanton, CA 94588 (United States); Doughty, D.H.; Roth, E.P. [Lithium Battery Department, Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2007-01-01

A simple approach for using accelerating rate calorimetry data to simulate the thermal abuse resistance of battery packs is described. The thermal abuse tolerance of battery packs is estimated based on the exothermic behavior of a single cell and an energy balance than accounts for radiative, conductive, and convective heat transfer modes of the pack. For the specific example of a notebook computer pack containing eight 18650-size cells, the effects of cell position, heat of reaction, and heat-transfer coefficient are explored. Thermal runaway of the pack is more likely to be induced by thermal runaway of a single cell when that cell is in good contact with other cells and is close to the pack wall. (author)

Hardfacing and packings for improved valve performance

International Nuclear Information System (INIS)

Aikin, J.A.; Patrick, J.N.F.; Inglis, I.

2003-01-01

The CANDU Owners Group (COG), Chemistry, Materials and Components (CMC) Program has supported an ongoing program on valve maintenance and performance for several years. An overview is presented of recent work on iron-based hardfacing, packing qualification, friction testing of polytetrafluoroethylene (PTFE) packings, and an investigation of re-torquing valve packing. Based on this program, two new valve-packing materials have been qualified for use in CANDU stations. By doing this, CANDU maintenance can avoid having only one packing qualified for station use, as well as assess the potential impact of the industry trend towards using lower gland loads. The results from corrosion tests by AECL and the coefficient of friction studies at Battelle' s tribology testing facilities on Delcrome 910, an iron-based hardfacing alloy, indicate it is an acceptable replacement for Stellite 6 under certain conditions. This information can be used to update in-line valve purchasing specifications. The renewed interest in friction characteristics, and environmental qualification (EQ) of packing containing PTFE has resulted in a new test program in these areas. The COG-funded valve programs have resulted in modifications to design specifications for nuclear station in-line valves and have led to better maintenance practices and valve reliability. In the end, this means lower costs and cheaper electricity. (author)

Enantioseparation of dansyl amino acids by HPLC on a monolithic column dynamically coated with a vancomycin derivative.

Science.gov (United States)

Pittler, Elfriede; Schmid, Martin G

2010-11-01

In this work a chiral stationary phase was prepared by dynamically coating a monolithic reversed-phase HPLC column with a vancomycin-derivative as chiral selector. A hydrophobic alkyl-chain was attached to the vancomycin molecule, providing the immobilization of the chiral selector on the reversed-phase material. Dansyl amino acids were chosen as model analytes for testing the separation power of the dynamically coated phase. All investigated compounds were separated into their enantiomers. Compared with a conventionally packed vancomycin-CSP, a reversal of the enantiomer elution order was obtained. Copyright © 2010 John Wiley & Sons, Ltd.

Distillation Column Flooding Predictor

Energy Technology Data Exchange (ETDEWEB)

George E. Dzyacky

2010-11-23

The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillation columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid

Annular pulse column development studies

International Nuclear Information System (INIS)

Benedict, G.E.

1980-01-01

The capacity of critically safe cylindrical pulse columns limits the size of nuclear fuel solvent extraction plants because of the limited cross-sectional area of plutonium, U-235, or U-233 processing columns. Thus, there is a need to increase the cross-sectional area of these columns. This can be accomplished through the use of a column having an annular cross section. The preliminary testing of a pilot-plant-scale annular column has been completed and is reported herein. The column is made from 152.4-mm (6-in.) glass pipe sections with an 89-mm (3.5-in.) o.d. internal tube, giving an annular width of 32-mm (1.25-in.). Louver plates are used to swirl the column contents to prevent channeling of the phases. The data from this testing indicate that this approach can successfully provide larger-cross-section critically safe pulse columns. While the capacity is only 70% of that of a cylindrical column of similar cross section, the efficiency is almost identical to that of a cylindrical column. No evidence was seen of any non-uniform pulsing action from one side of the column to the other

Structural characterization of the packings of granular regular polygons.

Science.gov (United States)

Wang, Chuncheng; Dong, Kejun; Yu, Aibing

2015-12-01

By using a recently developed method for discrete modeling of nonspherical particles, we simulate the random packings of granular regular polygons with three to 11 edges under gravity. The effects of shape and friction on the packing structures are investigated by various structural parameters, including packing fraction, the radial distribution function, coordination number, Voronoi tessellation, and bond-orientational order. We find that packing fraction is generally higher for geometrically nonfrustrated regular polygons, and can be increased by the increase of edge number and decrease of friction. The changes of packing fraction are linked with those of the microstructures, such as the variations of the translational and orientational orders and local configurations. In particular, the free areas of Voronoi tessellations (which are related to local packing fractions) can be described by log-normal distributions for all polygons. The quantitative analyses establish a clearer picture for the packings of regular polygons.

Max–min Bin Packing Algorithm and its application in nano-particles filling

International Nuclear Information System (INIS)

Zhu, Dingju

2016-01-01

With regard to existing bin packing algorithms, higher packing efficiency often leads to lower packing speed while higher packing speed leads to lower packing efficiency. Packing speed and packing efficiency of existing bin packing algorithms including NFD, NF, FF, FFD, BF and BFD correlates negatively with each other, thus resulting in the failure of existing bin packing algorithms to satisfy the demand of nano-particles filling for both high speed and high efficiency. The paper provides a new bin packing algorithm, Max–min Bin Packing Algorithm (MM), which realizes both high packing speed and high packing efficiency. MM has the same packing speed as NFD (whose packing speed ranks no. 1 among existing bin packing algorithms); in case that the size repetition rate of objects to be packed is over 5, MM can realize almost the same packing efficiency as BFD (whose packing efficiency ranks No. 1 among existing bin packing algorithms), and in case that the size repetition rate of objects to be packed is over 500, MM can achieve exactly the same packing efficiency as BFD. With respect to application of nano-particles filling, the size repetition rate of nano particles to be packed is usually in thousands or ten thousands, far higher than 5 or 500. Consequently, in application of nano-particles filling, the packing efficiency of MM is exactly equal to that of BFD. Thus the irreconcilable conflict between packing speed and packing efficiency is successfully removed by MM, which leads to MM having better packing effect than any existing bin packing algorithm. In practice, there are few cases when the size repetition of objects to be packed is lower than 5. Therefore the MM is not necessarily limited to nano-particles filling, and can also be widely used in other applications besides nano-particles filling. Especially, MM has significant value in application of nano-particles filling such as nano printing and nano tooth filling.

Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste.

Science.gov (United States)

Vilar, Vítor J P; Loureiro, José M; Botelho, Cidália M S; Boaventura, Rui A R

2008-06-15

Continuous metal ions biosorption from Pb/Cu and Pb/Cd solutions onto seaweed Gelidium sesquipedale and a composite material prepared from an industrial algal waste was performed in a packed bed column. A binary Langmuir equation describes well the equilibrium data and indicates a good adsorption capacity. In the sorption process, Cd and Cu break through the column faster than Pb due to its lower affinity for the biosorbent. An overshoot in the outlet Cd concentration was observed and explained by competitive adsorption between Pb and Cd, whereby the higher Pb affinity for the biosorbent displaces bound Cd ions. A small overshoot happens for Cu adsorption in the presence of Pb ions. Desorption using 0.1 M HNO3 as eluant, was 100% effective. A mass transfer model for the adsorption and desorption processes, considering an external and intraparticle film resistance, adequately simulates the column performance. A binary Langmuir equation was used to describe equilibrium for the saturation process and a mass action law for the desorption process. Elution process is defined as an ion exchange mechanism, between protons and metal ions.

Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste

Energy Technology Data Exchange (ETDEWEB)

Vilar, Vitor J.P. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: vilar@fe.up.pt; Loureiro, Jose M. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: loureiro@fe.up.pt; Botelho, Cidalia M.S. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: cbotelho@fe.up.pt; Boaventura, Rui A.R. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: bventura@fe.up.pt

2008-06-15

Continuous metal ions biosorption from Pb/Cu and Pb/Cd solutions onto seaweed Gelidium sesquipedale and a composite material prepared from an industrial algal waste was performed in a packed bed column. A binary Langmuir equation describes well the equilibrium data and indicates a good adsorption capacity. In the sorption process, Cd and Cu break through the column faster than Pb due to its lower affinity for the biosorbent. An overshoot in the outlet Cd concentration was observed and explained by competitive adsorption between Pb and Cd, whereby the higher Pb affinity for the biosorbent displaces bound Cd ions. A small overshoot happens for Cu adsorption in the presence of Pb ions. Desorption using 0.1 M HNO{sub 3} as eluant, was 100% effective. A mass transfer model for the adsorption and desorption processes, considering an external and intraparticle film resistance, adequately simulates the column performance. A binary Langmuir equation was used to describe equilibrium for the saturation process and a mass action law for the desorption process. Elution process is defined as an ion exchange mechanism, between protons and metal ions.

Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste

International Nuclear Information System (INIS)

Vilar, Vitor J.P.; Loureiro, Jose M.; Botelho, Cidalia M.S.; Boaventura, Rui A.R.

2008-01-01

Continuous metal ions biosorption from Pb/Cu and Pb/Cd solutions onto seaweed Gelidium sesquipedale and a composite material prepared from an industrial algal waste was performed in a packed bed column. A binary Langmuir equation describes well the equilibrium data and indicates a good adsorption capacity. In the sorption process, Cd and Cu break through the column faster than Pb due to its lower affinity for the biosorbent. An overshoot in the outlet Cd concentration was observed and explained by competitive adsorption between Pb and Cd, whereby the higher Pb affinity for the biosorbent displaces bound Cd ions. A small overshoot happens for Cu adsorption in the presence of Pb ions. Desorption using 0.1 M HNO 3 as eluant, was 100% effective. A mass transfer model for the adsorption and desorption processes, considering an external and intraparticle film resistance, adequately simulates the column performance. A binary Langmuir equation was used to describe equilibrium for the saturation process and a mass action law for the desorption process. Elution process is defined as an ion exchange mechanism, between protons and metal ions

Determination of trace lithium in uranium compounds by adsorption on activated alumina using a micro-column method.

Science.gov (United States)

Luo, Ming-Biao; Li, Bo-Ping; Yang, Zhi; Liu, Wei; Sun, Yu-Zhen

2008-08-01

A novel method using a micro-column packed with active alumina as solid phase was proposed for separation of trace lithium from uranium compounds prior to determination. The method is based on a preliminary chromatographic separation of the total amount of uranium. This separation involves passing the solution containing sodium carbonate through active alumina and then eluting the trace lithium retained by the solid phase with a solution of sulfuric acid. Two modes, off-line and on-line micro-column preconcentration, were performed. In conjunction with atomic absorption spectrometry, this on-line preconcentration technique allows a determination of lithium at 10(-9) level. Both off-line and on-line mode operation conditions were investigated in separation and determination of trace lithium by micro-column method (length of column bed, flow rate, etc.). The adsorption capacity of activated alumina was found to be 343 microg g(-1) for lithium. Under the optimal operation condition, the detection limit (DL) of on-line preconcentration corresponding to three times the standard deviation of the blank (S/N = 3) was found to be 1.3 ng mL(-1) and the RSD of this method is 3.32% (n = 5). The on-line calibration graph was linear over the range 20 - 200 ng mL(-1). A good preconcentration factor 820 was achieved by experiment under the on-line mode. The developed method was applied to the analysis of trace lithium in nuclear grade uranium compounds.

Evaluation of an activated carbon packed bed for the adsorption of phenols from petroleum refinery wastewater.

Science.gov (United States)

El-Naas, Muftah H; Alhaija, Manal A; Al-Zuhair, Sulaiman

2017-03-01

The performance of an adsorption column packed with granular activated carbon was evaluated for the removal of phenols from refinery wastewater. The effects of phenol feed concentration (80-182 mg/l), feed flow rate (5-20 ml/min), and activated carbon packing mass (5-15 g) on the breakthrough characteristics of the adsorption system were determined. The continuous adsorption process was simulated using batch data and the parameters for a new empirical model were determined. Different dynamic models such as Adams-Bohart, Wolborsko, Thomas, and Yoon-Nelson models were also fitted to the experimental data for the sake of comparison. The empirical, Yoon-Nelson and Thomas models showed a high degree of fitting at different operation conditions, with the empirical model giving the best fit based on the Akaike information criterion (AIC). At an initial phenol concentration of 175 mg/l, packing mass of 10 g, a flow rate of 10 ml/min and a temperature of 25 °C, the SSE of the new empirical and Thomas models were identical (248.35) and very close to that of the Yoon-Nelson model (259.49). The values were significantly lower than that of the Adams-Bohart model, which was determined to be 19,358.48. The superiority of the new empirical model and the Thomas model was also confirmed from the values of the R 2 and AIC, which were 0.99 and 38.3, respectively, compared to 0.92 and 86.2 for Adams-Bohart model.

Forced Convection Heat Transfer of a sphere in Packed Bed Arrangement

International Nuclear Information System (INIS)

Lee, Dong-Young; Chung, Bum-Jin

2016-01-01

This paper analysis and discuss the forced convective heat transfer from heated single sphere, which is buried in unheated packed bed, depending on Re d with porosity. The present work determines the test matrix for the packed bed experiment. And this study discuss difference of heat transfer according to the location of heated sphere and compared heated bed with heated sphere in packed bed and compared FCC (Face Centered Cubic), HCP (Hexagonal Closed Packed) structured packed bed with random packed. This paper is to discuss and make the plan to experiment the heat transfer for depending on location of heated single sphere in unheated packed bed, to compare single sphere in packed bed with heated packed bed and to compare the structured packed bed with random packed bed. The Nu d increase as heated single sphere is close to the wall and bottom because of increasing porosity and enhancing eddy motion respectively. The existing experiment of heated sphere in packed bed do not consider the preheating effect which decrease heat transfer on downstream. The heat transfer rate of structured packed bed is different from random packed bed because of unsteady flow in random packed bed. In this study, mass transfer experiments will replace heat transfer experiments based on analogy concept. An electroplating system is adopted using limiting current technique

Forced Convection Heat Transfer of a sphere in Packed Bed Arrangement

Energy Technology Data Exchange (ETDEWEB)

Lee, Dong-Young; Chung, Bum-Jin [Kyung Hee University, Yongin (Korea, Republic of)

2016-10-15

This paper analysis and discuss the forced convective heat transfer from heated single sphere, which is buried in unheated packed bed, depending on Re{sub d} with porosity. The present work determines the test matrix for the packed bed experiment. And this study discuss difference of heat transfer according to the location of heated sphere and compared heated bed with heated sphere in packed bed and compared FCC (Face Centered Cubic), HCP (Hexagonal Closed Packed) structured packed bed with random packed. This paper is to discuss and make the plan to experiment the heat transfer for depending on location of heated single sphere in unheated packed bed, to compare single sphere in packed bed with heated packed bed and to compare the structured packed bed with random packed bed. The Nu{sub d} increase as heated single sphere is close to the wall and bottom because of increasing porosity and enhancing eddy motion respectively. The existing experiment of heated sphere in packed bed do not consider the preheating effect which decrease heat transfer on downstream. The heat transfer rate of structured packed bed is different from random packed bed because of unsteady flow in random packed bed. In this study, mass transfer experiments will replace heat transfer experiments based on analogy concept. An electroplating system is adopted using limiting current technique.

Nuclear reactor control column

International Nuclear Information System (INIS)

Bachovchin, D.M.

1982-01-01

The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest crosssectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor

Domain Discretization and Circle Packings

DEFF Research Database (Denmark)

Dias, Kealey

A circle packing is a configuration of circles which are tangent with one another in a prescribed pattern determined by a combinatorial triangulation, where the configuration fills a planar domain or a two-dimensional surface. The vertices in the triangulation correspond to centers of circles...... to domain discretization problems such as triangulation and unstructured mesh generation techniques. We wish to ask ourselves the question: given a cloud of points in the plane (we restrict ourselves to planar domains), is it possible to construct a circle packing preserving the positions of the vertices...... and constrained meshes having predefined vertices as constraints. A standard method of two-dimensional mesh generation involves conformal mapping of the surface or domain to standardized shapes, such as a disk. Since circle packing is a new technique for constructing discrete conformal mappings, it is possible...

The pursuit of perfect packing

CERN Document Server

Weaire, Denis

2000-01-01

In 1998 Thomas Hales dramatically announced the solution of a problem that has long teased eminent mathematicians: what is the densest possible arrangement of identical spheres? The Pursuit of Perfect Packing recounts the story of this problem and many others that have to do with packing things together. The examples are taken from mathematics, physics, biology, and engineering, including the arrangement of soap bubbles in foam, atoms in a crystal, the architecture of the bee''s honeycomb, and the structure of the Giant''s Causeway. Using an informal style and with key references, the book also includes brief accounts of the lives of many of the scientists who devoted themselves to problems of packing over many centuries, together with wry comments on their efforts. It is an entertaining introduction to the field for both specialists and the more general public.

Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters.

Science.gov (United States)

Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

2016-01-21

This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

Random close packing of hard spheres and disks

International Nuclear Information System (INIS)

Berryman, J.G.

1983-01-01

A simple definition of random close packing of hard spheres is presented, and the consequences of this definition are explored. According to this definition, random close packing occurs at the minimum packing fraction eta for which the median nearest-neighbor radius equals the diameter of the spheres. Using the radial distribution function at more dilute concentrations to estimate median nearest-neighbor radii, lower bounds on the critical packing fraction eta/sub RCP/ are obtained and the value of eta/sub RCP/ is estimated by extrapolation. Random close packing is predicted to occur for eta/sub RCP/ = 0.64 +- 0.02 in three dimensions and eta/sub RCP/ = 0.82 +- 0.02 in two dimensions. Both of these predictions are shown to be consistent with the available experimental data

Improvements in solvent extraction columns

International Nuclear Information System (INIS)

Aughwane, K.R.

1987-01-01

Solvent extraction columns are used in the reprocessing of irradiated nuclear fuel. For an effective reprocessing operation a solvent extraction column is required which is capable of distributing the feed over most of the column. The patent describes improvements in solvent extractions columns which allows the feed to be distributed over an increased length of column than was previously possible. (U.K.)

New iodine filter pack design

International Nuclear Information System (INIS)

Blackbee, B.A.

1977-10-01

To enable Naval Emergency Monitoring Teams to fulfil their role in the field it was necessary to locate or design a replacement filter pack for the collection of radioactive iodine air samples. Collaboration with the Berkeley Laboratories of the Central Electricity Generating Board provided the necessary starting point for a suitable type of package. Further development by NGTE (West Drayton) yielded the improved filter pack which is the subject of this memorandum. (author)

36 CFR 1002.16 - Horses and pack animals.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Horses and pack animals. 1002... AND RECREATION § 1002.16 Horses and pack animals. The following are prohibited: (a) The use of animals other than those designated as “pack animals” for purposes of transporting equipment. (b) The use of...

36 CFR 2.16 - Horses and pack animals.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Horses and pack animals. 2.16... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.16 Horses and pack animals. The following are prohibited: (a) The use of animals other than those designated as “pack animals” for purposes of transporting...

Understanding and diminishing the extra-column band broadening effects in supercritical fluid chromatography.

Science.gov (United States)

De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

2015-07-17

Supercritical fluid chromatography, where a low-viscosity mobile phase such as carbon dioxide is used, proves to be an excellent technique for fast and efficient separations, especially when sub-2μm particles are used. However, to achieve high velocities when using these small particles, and in order to stay within the flow rate range of current SFC-instruments, narrow columns (e.g. 2.1mm ID) must be used. Unfortunately, state-of-the-art instrumentation is limiting the full separation power of these narrower columns due to significant extra-column band broadening effects. The present work identifies and quantifies the different contributions to extra-column band broadening in SFC such as the influence of the sample solvent, injection volume, extra-column volumes and detector cell volume/design. When matching the sample solvent to the mobile phase in terms of elution strength and polarity (e.g. using hexane/ethanol/isopropanol 85/10/5vol%) and lowering the injection volume to 0.4μL, the plate count can be increased from 7600 to 21,300 for a low-retaining compound (k'=2.3) on a 2.1mm×150mm column (packed with 1.8μm particles). The application of a water/acetonitrile mixture as sample solvent was also investigated. It was found that when the volumetric ratio of water/acetonitrile was optimized, only a slightly lower plate count was measured compared to the hexane-based solvent when minimizing injection and extra-column volume. This confirms earlier results that water/acetonitrile can be used if water-soluble samples are considered or when a less volatile solvent is preferred. Minimizing the ID of the connection capillaries from 250 to 65μm, however, gives no further improvement in obtained efficiency for early-eluting compounds when a standard system configuration with optimized sample solvent was used. When switching to a state-of-the-art detector design with reduced (dispersion) volume (1.7-0.6μL), an increase in plate count is observed (from 11,000 to 14

Packing Smart

Centers for Disease Control (CDC) Podcasts

2011-08-22

In this podcast for kids, the Kidtastics talk about packing a lunch that's not boring and is full of the power and energy kids need to make it through the day.  Created: 8/22/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/22/2011.

21 CFR 133.124 - Cold-pack cheese food.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cold-pack cheese food. 133.124 Section 133.124 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Cheese and Related Products § 133.124 Cold-pack cheese food. (a)(1) Cold-pack cheese food is the food...

Elution behavior of poly(ethylene glycol) through poly(vinyl alcohol) gel column using several solvents as eluents

International Nuclear Information System (INIS)

Hirayama, Chuichi; Motozato, Yoshiaki; Matsumoto, Kazuaki.

1983-01-01

γ-Irradiated poly(vinyl alcohol) beads, which were sufficiently allowed to swell in water, were washed with methanol, and then were packed into column. Gel chromatography was performed using methanol, benzene, esters and ketones as eluents and poly(ethylene glycol) as a sample. When the elution was carried out using methanol and benzene as eluents, elution behavior of samples was ordinary. When ethyl formate, methyl acetate and ethyl propionate were used as eluents, samples were slightly adsorbed and the elution was delayed. In the case the elution was carried out using ethyl acetate, propyl acetate, butyl acetate and ethyl methyl ketone as eluents, samples were adsorbed strongly on the bed material, and the adsorption curve was analogous to the calibration curve using methanol as an eluent. Dried poly(vinyl alcohol) gel as a packing material, showed ordinary elution behaviors for the samples. The adsorption of poly(ethylene glycol) on the present bed material was attributed to the existence of hydrated water on poly(vinyl alcohol) gel matrix. (author)

( Anogeissus leiocarpus ) timber columns

African Journals Online (AJOL)

A procedure for designing axially loaded Ayin (Anogeissus leiocarpus) wood column or strut has been investigated. Instead of the usual categorization of columns into short, intermediate and slender according to the value of slenderness ratio, a continuous column formula representing the three categories was derived.

The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2

Energy Technology Data Exchange (ETDEWEB)

Soler, Josep M. [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain)], E-mail: jsoler@ija.csic.es; Boi, Marco [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Mogollon, Jose Luis [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Instituto de Ciencias de la Tierra, Universidad Central de Venezuela, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cama, Jordi; Ayora, Carlos [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Nico, Peter S.; Tamura, Nobumichi; Kunz, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

2008-12-15

Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H{sub 2}SO{sub 4}, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L{sup -1}, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe-oxyhydroxysulfates (Fe(III)-SO{sub 4}-H{sup +} solutions) or Fe-oxyhydroxychlorides (Fe(III)-Cl-H{sup +} solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to {approx}6-7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)-SO{sub 4}-H{sup +} solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)-Cl-H{sup +} solutions.

Cell packing structures

KAUST Repository

Pottmann, Helmut; Jiang, Caigui; Hö binger, Mathias; Wang, Jun; Bompas, Philippe; Wallner, Johannes

2015-01-01

optimization schemes for the computation of quad-based support structures. Hex-dominant structures may be designed via Voronoi tessellations, power diagrams, sphere packings and various extensions of these concepts. Apart from the obvious application as load

SEPTOPLASTY WITH AND WITHOUT NASAL PACKING: A COMPARATIVE STUDY

Directory of Open Access Journals (Sweden)

Mitta

2016-05-01

Full Text Available Septoplasty is one of the most commonly performed surgeries in rhinology to relieve nasal obstruction of patients with distortion in the midline cartilage or septum of the nose to relieve nasal obstruction of patient and findings consistent with nasal endoscopy. The anterior nasal packing routinely done following septoplasty is usually conventional and not evidence based. The purpose of nasal packing is to obtain haemostasis, enhance opposition of septal flaps, avoid septal haematoma formation, close the dead space, avoid synechiae formation, provide support to septal cartilage and prevent its displacement. OBJECTIVE This study intends to evaluate the effects of nasal packing on surgical success and related complications in septoplasty. MATERIALS AND METHODS The present clinical prospective and randomised study was carried out on patients attending Otorhinolaryngology Department of Santhiram Medical College & General Hospital between March 2012 and March 2015. Patients undergoing septoplasty were randomised either to receive anterior nasal packing or to not receive nasal packing postoperatively. RESULTS Levels of pain experienced by patients with nasal packing postoperatively during the initial 24 hours postoperatively and during the removal of the pack were significantly more. Post-operative headache, epiphora, swallowing discomfort and sleep disturbance were more in patients with nasal packing and statistically (p.05. Septal haematoma, adhesions and local infections in both groups were statistically insignificant (p>.05. CONCLUSION Septoplasty enhances the standard of living of patients with septal deviation and nasal obstruction. Our study results suggest that nasal packing after septoplasty is not obligatory. Nasal packing causes considerably more pain and complications, and it should be reserved only for those who have bleeding predisposition.

Fast charge implications: Pack and cell analysis and comparison

Science.gov (United States)

Tanim, Tanvir R.; Shirk, Matthew G.; Bewley, Randy L.; Dufek, Eric J.; Liaw, Bor Yann

2018-03-01

This study investigates the effect of 50-kW (about 2C) direct current fast charging on a full-size battery electric vehicle's battery pack in comparison to a pack exclusively charged at 3.3 kW, which is the common alternating current Level 2 charging power level. Comparable scaled charging protocols are also independently applied to individual cells at three different temperatures, 20 °C, 30 °C, and 40 °C, to perform a comparative analysis with the packs. Dominant cell-level aging modes were identified through incremental capacity analysis and compared with full packs to gain a clear understanding of additional key factors that affect pack aging. While the cell-level study showed a minor impact on performance due to direct current fast charging, the packs showed a significantly higher rate of capacity fade under similar charging protocols. This indicates that pack-level aging cannot be directly extrapolated from cell evaluation. Delayed fast charging, completing shortly before discharge, was found to have less of an impact on battery degradation than conventional alternating current Level 2 charging.

Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

Science.gov (United States)

Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu

2016-07-15

The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temperature-based on-column solute focusing in capillary liquid chromatography reduces peak broadening from precolumn dispersion and volume overload when used alone or with solvent-based focusing

Science.gov (United States)

Groskreutz, Stephen R.; Horner, Anthony R.; Weber, Stephen G.

2015-01-01

On-column focusing is essential for satisfactory performance using capillary scale columns. On-column focusing results from generating transient conditions at the head of the column that lead to high solute retention. Solvent-based on-column focusing is a well-known approach to achieve this. Temperature-assisted on-column focusing (TASF) can also be effective. TASF improves focusing by cooling a short segment of the column inlet to a temperature that is lower than the column temperature during the injection and then rapidly heating the focusing segment to the match the column temperature. A troublesome feature of an earlier implementation of TASF was the need to leave the capillary column unpacked in that portion of the column inside the fitting connecting it to the injection valve. We have overcome that problem in this work by packing the head of the column with solid silica spheres. In addition, technical improvements to the TASF instrumentation include: selection of a more powerful thermo-electric cooler to create faster temperature changes and electronic control for easy incorporation into conventional capillary instruments. Used in conjunction with solvent-based focusing and with isocratic elution, volumes of paraben samples (esters of p-hydroxybenzoic acid) up to 4.5-times the column liquid volume can be injected without significant bandspreading due to volume overload. Interestingly, the shapes of the peaks from the lowest volume injections that we can make, 30 nL, are improved when using TASF. TASF is very effective at reducing the detrimental effects of precolumn dispersion using isocratic elution. Finally, we show that TASF can be used to focus the neuropeptide galanin in a sample solvent with elution strength stronger than the mobile phase. Here, the stronger solvent is necessitated by the need to prevent peptide adsorption prior to and during analysis. PMID:26091787

SPH Modelling of Sea-ice Pack Dynamics

Science.gov (United States)

Staroszczyk, Ryszard

2017-12-01

The paper is concerned with the problem of sea-ice pack motion and deformation under the action of wind and water currents. Differential equations describing the dynamics of ice, with its very distinct mateFfigrial responses in converging and diverging flows, express the mass and linear momentum balances on the horizontal plane (the free surface of the ocean). These equations are solved by the fully Lagrangian method of smoothed particle hydrodynamics (SPH). Assuming that the ice behaviour can be approximated by a non-linearly viscous rheology, the proposed SPH model has been used to simulate the evolution of a sea-ice pack driven by wind drag stresses. The results of numerical simulations illustrate the evolution of an ice pack, including variations in ice thickness and ice area fraction in space and time. The effects of different initial ice pack configurations and of different conditions assumed at the coast-ice interface are examined. In particular, the SPH model is applied to a pack flow driven by a vortex wind to demonstrate how well the Lagrangian formulation can capture large deformations and displacements of sea ice.

Thermal Modeling Analysis Of CST Media In The Small Column Ion Exchange Project

International Nuclear Information System (INIS)

Lee, S.

2010-01-01

Models have been developed to simulate the thermal characteristics of Crystalline Silicotitanate (CST) ion exchange media fully loaded with radioactive cesium in a column configuration and distributed within a waste storage tank. This work was conducted to support the Small Column Ion Exchange (SCIX) program which is focused on processing dissolved, high-sodium salt waste for the removal of specific radionuclides (including Cs-137, Sr-90, and actinides) within a High Level Waste (HLW) storage tank at the Savannah River Site. The SCIX design includes CST columns inserted and supported in the tank top risers for cesium removal. Temperature distributions and maximum temperatures across the column were calculated with a focus on process upset conditions. A two-dimensional computational modeling approach for the in-column ion-exchange domain was taken to include conservative, bounding estimates for key parameters such that the results would provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on CST. One salt processing scenario includes the transport of the loaded (and possibly ground) CST media to the treatment tank floor. Therefore, additional thermal modeling calculations were conducted using a three-dimensional approach to evaluate temperature distributions for the entire in-tank domain including distribution of the spent CST media either as a mound or a flat layer on the tank floor. These calculations included mixtures of CST with HLW sludge or loaded Monosodium Titanate (MST) media used for strontium/actinide sorption. The current full-scale design for the CST column includes one central cooling pipe and four outer cooling tubes. Most calculations assumed that the fluid within the column was stagnant (i.e. no buoyancy-induced flow) for a conservative estimate. A primary objective of these calculations was to estimate temperature distributions across packed CST beds

Direct contact condensation in packed beds

Energy Technology Data Exchange (ETDEWEB)

Li, Yi; Klausner, James F.; Mei, Renwei; Knight, Jessica [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

2006-12-15

A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated air inlet temperatures of 36, 40 and 43{sup o}C. The temperature and humidity data have been collected at the inlet and exit of the packed bed for different water to air mass flow ratios that vary between 0 and 2.5. A one-dimensional model based on conservation principles has been developed, which predicts the variation of temperature, humidity, and condensation rate through the condenser stages. Agreement between the model and experiments is very good. It is observed that the countercurrent flow stage condensation effectiveness is significantly higher than that for the co-current stage. The condensation heat and mass transfer rates were found to decrease when water blockages occur within the packed bed. Using high-speed digital cinematography, it was observed that this problem can occur at any operating condition, and is dependent on the packing surface wetting characteristics. This observation is used to explain the requirement for two different empirical constants, depending on packing diameter, suggested by Onda for the air side mass transfer coefficient correlation. (author)

Modi ed strip packing heuristics for the rectangular variable-sized ...

African Journals Online (AJOL)

Two packing problems are considered in this paper, namely the well-known strip packing problem (SPP) and the variable-sized bin packing problem (VSBPP). A total of 252 strip packing heuristics (and variations thereof) from the literature, as well as novel heuristics proposed by the authors, are compared statistically by ...

Reference book for design of valve packings, sealing high temperature water

International Nuclear Information System (INIS)

Doubt, G.L.

1976-01-01

Mockups of stuffing boxes for valves in the 1/4 to 1 in. (0.6-2.54cm) pipe size range and ASA 900 and up pressure class were tested to determine how temperature, stuffing box dimensions, packing compressive stress and stem surface finish affect water leak rate, packing friction torque and packing volume loss (creep). One brand of wire-reinforced asbestos braid on graphite-and-asbestos core packing was used in all tests. The theory of leakage through porous media was reviewed with emphasis on application to packed stuffing boxes, and a mathematical framework for relating leakage and packing friction to stuffing box dimensions and compressive stress was developed. The tests gave empirical relationships (1) for leak rate vs temperature, packing compressive stress, stem diameter and packing size, (2) for packing friction torque vs the above variables and (3) for packing creep vs temperature and stress. Packing stress affected leakage far more than any other variable, the leak rate being inversely proportional to stress to the 7.3 power at a packing temperature of 350 deg F (175 deg C). Factors which increase packing compression (density) have a strong reducing effect on leakage and a moderate to zero effect on packing friction torque. Surface finish had no visible effect on leakage, torque or creep. Empirical results and theory have been combined to show how stuffing boxes can be designed for a given leakage rate. Suggestions for decreasing leakage from existing high temperature stuffing boxes are included. (author)

A new pilot absorber for CO2 capture from flue gases: Measuring and modelling capture with MEA solution

DEFF Research Database (Denmark)

Sønderby, Tim L.; Carlsen, Kim B.; Fosbøl, Philip Loldrup

2013-01-01

A pilot absorber column for CO2 recovery from flue gases was constructed and tested with aqueous 30wt% monoethanolamine (MEA), a primary amine, as capture solvent. The pilot plant data were compared with a mathematical rate based packed-column model. The simulation results compared well...... with the pilot plant data. The packed height of the column can be varied from 1.6 to 8.2. m by means of five different liquid inlets. The column has an inner diameter of 100. mm and is packed with structured Mellapak 250Y packing. Counter-current flow is used. The pilot plant performance was investigated...

Pack stability in dip faces fitted with scraper conveyors

Energy Technology Data Exchange (ETDEWEB)

Schwartzmann, R

1978-01-01

This paper presents an account of an investigation conducted by CERCHAR, at the request of HBNPC, into the problems of goafside pack stability. Winning method and support and stowing techniques are described. Sets out the study methods used: systematic measurement (by direct or remote means) using an instrument developed by CERCHAR to investigate all aspects of in situ pack behaviour: settling, stresses, pressure on supports, etc. Gives the results of the investigation (tables and graphs) load-bearing capacity of the supports, deformation of the surrounding rock, convergence and stresses in the pack (figures, graphs), resistance of support-timber screen, model of in situ pack behaviour. Detailed conclusions (potential techniques, detailed study, practical improvements in packing techniques) are presented.

Scandinavian consumer preference for beef steaks packed with or without oxygen.

Science.gov (United States)

Aaslyng, M D; Tørngren, M A; Madsen, N T

2010-07-01

Beef steaks retail-packed with (80% O(2), 20% CO(2)) or without oxygen (either skin-packed or gas-packed (69.6% N(2), 30% CO(2), 0.04% CO or 70% N(2), 30% CO(2))) were compared by consumers in Denmark (n=382), Norway (n=316) and Sweden (n=374). Two pairs of two steaks - one steak packed in a high oxygen atmosphere and one packed without oxygen - were given to the consumers. They were instructed to prepare the steaks at home on two consecutive days, and two persons had to taste each steak. In Denmark, the oxygen-free packing was either gas packing with CO (69.6% N(2), 30% CO(2), 0.04% CO) or without CO (70% N(2), 30% CO(2)), in Norway it was either gas packing with CO (69.6% N(2), 30% CO(2), 0.04% CO) or skin packing, and in Sweden it was either skin packing or gas packing without CO (70% N(2), 30% CO(2)). The meat represented animals that were between 17 and 80 months old (Denmark) and young bulls (Norway and Sweden). Consumers in all three countries clearly preferred steaks packed without oxygen, in terms of overall liking, willingness to pay and their preferred choice of one steak. Furthermore, they preferred the oxygen-free steaks in terms of both overall liking and liking of tenderness, juiciness and flavour. In Sweden, many consumers would pay more than usual for the skin-packed steak, and it was more often chosen as the preferred steak out of the four compared with gas-packed without oxygen. No difference was seen between the two oxygen-free packing methods in Denmark and Norway. Copyright 2010 Elsevier Ltd. All rights reserved.

On contact numbers in random rod packings

NARCIS (Netherlands)

Wouterse, A.; Luding, Stefan; Philipse, A.P.

2009-01-01

Random packings of non-spherical granular particles are simulated by combining mechanical contraction and molecular dynamics, to determine contact numbers as a function of density. Particle shapes are varied from spheres to thin rods. The observed contact numbers (and packing densities) agree well

Packing of ganglioside-phospholipid monolayers

DEFF Research Database (Denmark)

Majewski, J.; Kuhl, T.L.; Kjær, K.

2001-01-01

Using synchrotron grazing-incidence x-ray diffraction (GIXD) and reflectivity, the in-plane and out-of-plane structure of mixed ganglioside-phospholipid monolayers was investigated at the air-water interface. Mixed monolayers of 0, 5, 10, 20, and 100 mol% ganglioside GM, and the phospholipid...... monolayers did not affect hydrocarbon tail packing (fluidization or condensation of the hydrocarbon region). This is in contrast to previous investigations of lipopolymer-lipid mixtures, where the packing structure of phospholipid monolayers was greatly altered by the inclusion of lipids bearing hydrophilic...

A Sensitive Method Approach for Chromatographic Analysis of Gas Streams in Separation Processes Based on Columns Packed with an Adsorbent Material

Directory of Open Access Journals (Sweden)

I. A. A. C. Esteves

2016-01-01

Full Text Available A sensitive method was developed and experimentally validated for the in-line analysis and quantification of gaseous feed and product streams of separation processes under research and development based on column chromatography. The analysis uses a specific mass spectrometry method coupled to engineering processes, such as Pressure Swing Adsorption (PSA and Simulated Moving Bed (SMB, which are examples of popular continuous separation technologies that can be used in applications such as natural gas and biogas purifications or carbon dioxide sequestration. These processes employ column adsorption equilibria on adsorbent materials, thus requiring real-time gas stream composition quantification. For this assay, an internal standard is assumed and a single-point calibration is used in a simple mixture-specific algorithm. The accuracy of the method was found to be between 0.01% and 0.25% (-mol for mixtures of CO2, CH4, and N2, tested as case-studies. This makes the method feasible for streams with quality control levels that can be used as a standard monitoring and analyzing procedure.

Optimization and simulation of tandem column supercritical fluid chromatography separations using column back pressure as a unique parameter.

Science.gov (United States)

Wang, Chunlei; Tymiak, Adrienne A; Zhang, Yingru

2014-04-15

Tandem column supercritical fluid chromatography (SFC) has demonstrated to be a useful technique to resolve complex mixtures by serially coupling two columns of different selectivity. The overall selectivity of a tandem column separation is the retention time weighted average of selectivity from each coupled column. Currently, the method development merely relies on extensive screenings and is often a hit-or-miss process. No attention is paid to independently adjust retention and selectivity contributions from individual columns. In this study, we show how tandem column SFC selectivity can be optimized by changing relative dimensions (length or inner diameter) of the coupled columns. Moreover, we apply column back pressure as a unique parameter for SFC optimization. Continuous tuning of tandem column SFC selectivity is illustrated through column back pressure adjustments of the upstream column, for the first time. In addition, we show how and why changing coupling order of the columns can produce dramatically different separations. Using the empirical mathematical equation derived in our previous study, we also demonstrate a simulation of tandem column separations based on a single retention time measurement on each column. The simulation compares well with experimental results and correctly predicts column order and back pressure effects on the separations. Finally, considerations on instrument and column hardware requirements are discussed.

Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices

DEFF Research Database (Denmark)

Ke, Yonggang; Voigt, Niels Vinther; Shih, William M.

2012-01-01

“Scaffolded DNA origami” has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry....... Here we report successful folding of multilayer DNA origami with helices arranged on a close-packed hexagonal lattice. This arrangement yields a higher density of helical packing and therefore higher resolution of spatial addressing than has been shown previously. We also demonstrate hybrid multilayer...... DNA origami with honeycomb-lattice, square-lattice, and hexagonal-lattice packing of helices all in one design. The availability of hexagonal close-packing of helices extends our ability to build complex structures using DNA nanotechnology....

Multilayer DNA origami packed on hexagonal and hybrid lattices.

Science.gov (United States)

Ke, Yonggang; Voigt, Niels V; Gothelf, Kurt V; Shih, William M

2012-01-25

"Scaffolded DNA origami" has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry. Here we report successful folding of multilayer DNA origami with helices arranged on a close-packed hexagonal lattice. This arrangement yields a higher density of helical packing and therefore higher resolution of spatial addressing than has been shown previously. We also demonstrate hybrid multilayer DNA origami with honeycomb-lattice, square-lattice, and hexagonal-lattice packing of helices all in one design. The availability of hexagonal close-packing of helices extends our ability to build complex structures using DNA nanotechnology. © 2011 American Chemical Society

Coalescence preference in dense packing of bubbles

Science.gov (United States)

Kim, Yeseul; Gim, Bopil; Gim, Bopil; Weon, Byung Mook

2015-11-01

Coalescence preference is the tendency that a merged bubble from the contact of two original bubbles (parent) tends to be near to the bigger parent. Here, we show that the coalescence preference can be blocked by densely packing of neighbor bubbles. We use high-speed high-resolution X-ray microscopy to clearly visualize individual coalescence phenomenon which occurs in micro scale seconds and inside dense packing of microbubbles with a local packing fraction of ~40%. Previous theory and experimental evidence predict a power of -5 between the relative coalescence position and the parent size. However, our new observation for coalescence preference in densely packed microbubbles shows a different power of -2. We believe that this result may be important to understand coalescence dynamics in dense packing of soft matter. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST and also was supported by Ministry of Science, ICT and Future Planning (2009-0082580) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry and Education, Science and Technology (NRF-2012R1A6A3A04039257).

Granular packing as model glass formers

International Nuclear Information System (INIS)

Wang Yujie

2017-01-01

Static granular packings are model hard-sphere glass formers. The nature of glass transition has remained a hotly debated issue. We review recent experimental progresses in using granular materials to study glass transitions. We focus on the growth of glass order with five-fold symmetry in granular packings and relate the findings to both geometric frustration and random first-order phase transition theories. (paper)

A Harmonic Algorithm for the 3D Strip Packing Problem

NARCIS (Netherlands)

N. Bansal (Nikhil); X. Han; K. Iwama; M. Sviridenko; G. Zhang (Guochuan)

2013-01-01

htmlabstractIn the three-dimensional (3D) strip packing problem, we are given a set of 3D rectangular items and a 3D box $B$. The goal is to pack all the items in $B$ such that the height of the packing is minimized. We consider the most basic version of the problem, where the items must be packed

Duration of Nasal Packs in the Management of Epistaxis

International Nuclear Information System (INIS)

Kundi, N. A.; Raza, M.

2015-01-01

Objective:To compare the efficacy of nasal packs for 12 and 24 hours in the management of epistaxis. Study Design: Quasi experimental study. Place and Duration of Study: Combined Military Hospital, Nowshera and Heavy Industries Taxilla Hospital, from October 2012 to April 2013. Methodology: A total of 60 patients presenting with epistaxis were selected and were divided into two groups of 30 patients each. Patients in both the groups were managed by nasal packs. In group-A packs were removed after 12 hours while in group-B after 24 hours. Symptoms of headache, lacrimation and recurrence of bleeding were recorded. SPSS 20 was used for data analysis and p-value less than 0.01 was considered significant. Results: There was significant difference for headache between removal of nasal packs after 12 hours and 24 hours (p < 0.001). There was significant difference for excessive lacrimation at 12 and 24 hours (p = 0.001). No significant difference was observed for recurrence of bleed when nasal packs were removed at 12 and 24 hours (p = 0.317). Conclusion: Duration in removal of nasal packs after 12 or 24 hours made a difference in the management of epistaxis. Symptoms of headache and excessive lacrimation were significantly higher when nasal packs were removed after 24 hours. It is recommended that patient could be managed with lesser duration of packs after episode of epistaxis to avoid inconvenience. (author)

Effect of packing fraction variations on reactivity in pebble-bed reactor

International Nuclear Information System (INIS)

Snoj, L.; Ravnik, M.

2004-01-01

The pebble-bed reactor (PBR) core consists of large number of randomly packed spherical fuel elements. The effect of fuel element packing density variations on multiplication factor in a typical PBR is studied using WIMS code. It is observed that at normal conditions the k-eff increases with packing fraction. Effects of secondary coolant ingress (water or molten lead) in the core at accidental conditions are studied at various packing densities. The effect of water ingress on reactivity depends strongly on water density and packing fraction and is prevailingly positive, while the lead ingress reduces multiplication factor regardless of lead effective density and packing fraction. Both effects are stronger at lower packing fractions. (author)

Cylinder valve packing nut studies

Energy Technology Data Exchange (ETDEWEB)

Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

1991-12-31

The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

Characteristics of illegal and legal cigarette packs sold in Guatemala.

Science.gov (United States)

Arevalo, Rodrigo; Corral, Juan E; Monzon, Diego; Yoon, Mira; Barnoya, Joaquin

2016-11-25

Guatemala, as a party to the Framework Convention on Tobacco Control (FCTC), is required to regulate cigarette packaging and labeling and eliminate illicit tobacco trade. Current packaging and labeling characteristics (of legal and illegal cigarettes) and their compliance with the FCTC is unknown. We sought to analyze package and label characteristics of illegal and legal cigarettes sold in Guatemala. We visited the 22 largest traditional markets in the country to purchase illegal cigarettes. All brands registered on tobacco industry websites were purchased as legal cigarettes. Analysis compared labeling characteristics of illegal and legal packs. Most (95%) markets and street vendors sold illegal cigarettes; 104 packs were purchased (79 illegal and 25 legal). Ten percent of illegal and none of the legal packs had misleading terms. Half of the illegal packs had a warning label covering 26 to 50% of the pack surface. All legal packs had a label covering 25% of the surface. Illegal packs were more likely to have information on constituents and emissions (85% vs. 45%, p Guatemala, neither illegal nor legal cigarette packs comply with FCTC labeling mandates. Urgent implementation and enforcement of the FCTC is necessary to halt the tobacco epidemic.

Generalized network improvement and packing problems

CERN Document Server

Holzhauser, Michael

2016-01-01

Michael Holzhauser discusses generalizations of well-known network flow and packing problems by additional or modified side constraints. By exploiting the inherent connection between the two problem classes, the author investigates the complexity and approximability of several novel network flow and packing problems and presents combinatorial solution and approximation algorithms. Contents Fractional Packing and Parametric Search Frameworks Budget-Constrained Minimum Cost Flows: The Continuous Case Budget-Constrained Minimum Cost Flows: The Discrete Case Generalized Processing Networks Convex Generalized Flows Target Groups Researchers and students in the fields of mathematics, computer science, and economics Practitioners in operations research and logistics The Author Dr. Michael Holzhauser studied computer science at the University of Kaiserslautern and is now a research fellow in the Optimization Research Group at the Department of Mathematics of the University of Kaiserslautern.

Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

Science.gov (United States)

Huz, Kateryna

2014-01-01

RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

Small Column Ion Exchange

International Nuclear Information System (INIS)

Huff, Thomas

2010-01-01

Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.

Selection of stationary phase particle geometry using X-ray computed tomography and computational fluid dynamics simulations.

Science.gov (United States)

Schmidt, Irma; Minceva, Mirjana; Arlt, Wolfgang

2012-02-17

The X-ray computed tomography (CT) is used to determine local parameters related to the column packing homogeneity and hydrodynamics in columns packed with spherically and irregularly shaped particles of same size. The results showed that the variation of porosity and axial dispersion coefficient along the column axis is insignificant, compared to their radial distribution. The methodology of using the data attained by CT measurements to perform a CFD simulation of a batch separation of model binary mixtures, with different concentration and separation factors is demonstrated. The results of the CFD simulation study show that columns packed with spherically shaped particles provide higher yield in comparison to columns packed with irregularly shaped particles only below a certain value of the separation factor. The presented methodology can be used for selecting a suited packing material for a particular separation task. Copyright © 2012 Elsevier B.V. All rights reserved.

Multi-Node Thermal System Model for Lithium-Ion Battery Packs: Preprint

Energy Technology Data Exchange (ETDEWEB)

Shi, Ying; Smith, Kandler; Wood, Eric; Pesaran, Ahmad

2015-09-14

Temperature is one of the main factors that controls the degradation in lithium ion batteries. Accurate knowledge and control of cell temperatures in a pack helps the battery management system (BMS) to maximize cell utilization and ensure pack safety and service life. In a pack with arrays of cells, a cells temperature is not only affected by its own thermal characteristics but also by its neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model, which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs. neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model, which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs.

Glottotecnologie didattiche per i migranti L’italiano fra le altre lingue nel progetto L-Pack (Citizenship Language Pack for Migrants in Europe

Directory of Open Access Journals (Sweden)

Pierangela Diadori

2017-01-01

Full Text Available Teaching languages to migrants through ICT L-Pack Project for Italian and other languages (Citizenship Language Pack for Migrants in EuropeThe most recent trends in technology and the internet, commonly called Web 2.0., have determined new concepts in teaching and learning that involve autonomy, multimodality and flexibility. New approaches to ‘knowledge by technology’ are changing both teachers’ and learners’ roles, responding to their different aims and needs. At the same time, nearly 4 million people are presently involved in massive migration processes all over Europe, coming either from outside Europe or from another EU member state. The EU policies on migrants state the importance of a basic knowledge of the host country’s language, history and institutions for an effective integration process, and EU governments are expected to contribute to this aim. This paper describes the European Project ‘L-PACK: Citizenship Language Pack For Migrants in Europe’ (2011-2016, whose main aim consisted in developing a series of internet video texts, accompanied with materials and resources to lead adult migrants to A2 level (according to QCER levels scale in different EU languages. The project has been developed in two main stages. In the first part of the programme, called L-Pack 1, from 2011 to 2013, the languages were Italian, Spanish, German, Lithuanian, Greek and Czech. In the second part, called L-Pack 2 extended, from 2014 to 2016, the project added English and French and was integrated with new resources and tools. The L-PACK course, which consists of 60 short video dialogues from everyday life, supported by comprehension activities and linguistic explanation and rules, is totally free and available through Youtube, Wikibooks and Soundcloud. The dedicated website http://www.l-pack.eu was visited by 120.000 users from 146 countries in the period 2011-2016. L-Pack teaching materials have also been used by teachers in classroom

Stress concentrations in an impregnated fibre bundle with random fibre packing

OpenAIRE

Swolfs, Y.; Gorbatikh, L.; Romanov, V.; Orlova, S.; Lomov, S. V.; Verpoest, I.

2013-01-01

The stress redistribution after a single fibre break is a fundamental issue in longitudinal strength models for unidirectional composites. Current models assume hexagonal or square fibre packings. In the present work, random fibre packings were modelled using 3D finite element analysis and compared to ordered fibre packings. Significant differences in the stress redistribution are found. Compared to square and hexagonal packings, random fibre packings result in smaller stress concentration fa...

Microbiological Quality of Blister Pack Tablets in Community ...

African Journals Online (AJOL)

Keywords: Blister pack, Community pharmacy, Good Manufacturing Practice, Microbial contamination,. Quality control ... High levels of microbial contamination in blister-packed tablets ... and their drugs approved by the Jordan Food and Drug ...

Reactive transport of Sr, Cs and Tc through a column packed with fracture-filling material

International Nuclear Information System (INIS)

Cui, D.; Eriksen, T.

1998-01-01

The migration behaviour of the fission products 90 Sr, 137 Cs and 99 Tc in a granite fracture-groundwater system was studied in column experiments using crushed Stripa granite fracture-filling material (125-250 μm) as a sorbent. Based on breakthrough curves of Sr 2+ , Cs + , TcO 4 - and anthraquinonsulphonate, the distribution ratio K d (cm 3 /g) values for Sr 2+ and Cs + were estimated to be 1.5 and 2 respectively; non-sorbing behaviour of TcO 4 - under oxic conditions was observed. The diffusion of Sr 2+ in the material is shown to be a kinetic-controlling step in the desorption process that followed the initial leaching. Under reducing conditions, it was found that TcO 4 - was reduced to TcO 2 .nH 2 O(s) by the Fe(II)-containing fracture-filling material and Tc(IV) aq was rapidly sorbed by the material. This observation proves that the migration of technetium under reducing conditions in deep groundwater systems will not only be controlled by the solubility of TcO 2 . nH 2 O(s) and the speed of groundwater flow but also by the rapid sorption of Tc(IV) aq on all available mineral surfaces. (orig.)

Improved Taxation Rate for Bin Packing Games

Science.gov (United States)

Kern, Walter; Qiu, Xian

A cooperative bin packing game is a N-person game, where the player set N consists of k bins of capacity 1 each and n items of sizes a 1, ⋯ ,a n . The value of a coalition of players is defined to be the maximum total size of items in the coalition that can be packed into the bins of the coalition. We present an alternative proof for the non-emptiness of the 1/3-core for all bin packing games and show how to improve this bound ɛ= 1/3 (slightly). We conjecture that the true best possible value is ɛ= 1/7.

Random close packing in protein cores.

Science.gov (United States)

Gaines, Jennifer C; Smith, W Wendell; Regan, Lynne; O'Hern, Corey S

2016-03-01

Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions ϕ ≈ 0.75, a value that is similar to close packing of equal-sized spheres. A limitation of these analyses was the use of extended atom models, rather than the more physically accurate explicit hydrogen model. The validity of the explicit hydrogen model was proved in our previous studies by its ability to predict the side chain dihedral angle distributions observed in proteins. In contrast, the extended atom model is not able to recapitulate the side chain dihedral angle distributions, and gives rise to large atomic clashes at side chain dihedral angle combinations that are highly probable in protein crystal structures. Here, we employ the explicit hydrogen model to calculate the packing fraction of the cores of over 200 high-resolution protein structures. We find that these protein cores have ϕ ≈ 0.56, which is similar to results obtained from simulations of random packings of individual amino acids. This result provides a deeper understanding of the physical basis of protein structure that will enable predictions of the effects of amino acid mutations to protein cores and interfaces of known structure.

Minimal packing duration in close reduction for nasal bone fracture treatment.

Science.gov (United States)

Choi, Dong Sik; Lee, Jeong Woo; Yang, Jung Dug; Chung, Ho Yun; Cho, Byung Chae; Choi, Kang Young

2015-04-15

Nasal bone fracture is the most common type of facial bone fracture. The optimal duration of the packing after closed reduction has been a controversial issue. The packing has several disadvantages such as blocking the nasal airway, causing infection and a headache, which is the most common immediate complication. The present study investigated the minimal and optimal duration of the nasal packing following reduction surgery of nasal bone fracture. A prospective study was performed for the patients undergoing reduction surgery following nasal bone fracture between July 2010 and June 2012. The patients were categorised into three groups according to the duration of nasal packing. For the patients treated between July 2010 and June 2011, nasal packing was maintained for 5 days. For those between July 2011 and December 2011, packing was maintained for 3 days. For those between January 2012 and June 2012, the packing was removed after 1 day. The computed tomography scan and the cephalolateral X-ray were checked at immediate postoperative period after packing removal and 6 months postoperatively. The alteration of heights, deviations, and nasal bone contours with time passage were compared among three groups. The patient satisfaction survey was also performed and compared. A total of 530 patients including 322 of the 5-days packing group, 102 of the 3-days group, and 106 of the 1-day group were enrolled. There was no statistically significant difference between the groups in terms of heights, deviations, and nasal bone contours (p-value ≥ 0.05). In the patient satisfaction survey, the 1-day packing group complained of discomfort related to nasal packing and headache symptoms much less, compared to the other two groups. The present study demonstrated that 1-day packing had comparable postoperative outcome with reducing the patients' discomfort. As such, a longer packing duration was not needed to achieve stable results one day is a reasonable packing time for most

Economics Action Pack.

Science.gov (United States)

McDonald's Corp., Oak Brook, IL.

One of five McDonald's Action Packs, this learning package introduces intermediate grade students to basic economic concepts. The fourteen activities include the topics of consumption (4 activities), production (5), the market system (3), a pretest, and a posttest. Specific titles under consumption include The Wonderful Treasure Tree (introduction…

Two generalizations of column-convex polygons

International Nuclear Information System (INIS)

Feretic, Svjetlan; Guttmann, Anthony J

2009-01-01

Column-convex polygons were first counted by area several decades ago, and the result was found to be a simple, rational, generating function. In this work we generalize that result. Let a p-column polyomino be a polyomino whose columns can have 1, 2, ..., p connected components. Then column-convex polygons are equivalent to 1-convex polyominoes. The area generating function of even the simplest generalization, namely 2-column polyominoes, is unlikely to be solvable. We therefore define two classes of polyominoes which interpolate between column-convex polygons and 2-column polyominoes. We derive the area generating functions of those two classes, using extensions of existing algorithms. The growth constants of both classes are greater than the growth constant of column-convex polyominoes. Rather tight lower bounds on the growth constants complement a comprehensive asymptotic analysis.

Sugar microanalysis by HPLC with benzoylation: improvement via introduction of a C-8 cartridge and a high efficiency ODS column.

Science.gov (United States)

Miyagi, Michiko; Yokoyama, Hirokazu; Hibi, Toshifumi

2007-07-01

An HPLC protocol for sugar microanalysis based on the formation of ultraviolet-absorbing benzoyl chloride derivatives was improved. Here, samples were prepared with a C-8 cartridge and analyzed with a high efficiency ODS column, in which porous spherical silica particles 3 microm in diameter were packed. These devices allowed us to simultaneously quantify multiple sugars and sugar alcohols up to 10 ng/ml and to provide satisfactory separations of some sugars, such as fructose and myo-inositol and sorbitol and mannitol. This protocol, which does not require special apparatuses, should become a powerful tool in sugar research.

Packing parameters effect on injection molding of polypropylene nanostructured surfaces

DEFF Research Database (Denmark)

Calaon, Matteo; Tosello, Guido; Hansen, Hans Nørgaard

2012-01-01

having a diameter of 500 nm was employed. The tool insert surface was produced using chemical-based-batch techniques such aluminum anodization and nickel electroplating. During the injection molding process, polypropylene (PP) was employed as material and packing phase parameters (packing time, packing...

Performance of high-rate gravel-packed oil wells

Energy Technology Data Exchange (ETDEWEB)

Unneland, Trond

2001-05-01

Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for

New techniques for analysis of organic pollutants in drinking water

Energy Technology Data Exchange (ETDEWEB)

Kissinger, L.D.

1979-01-01

An abstractor packing prepared by coating Chromosorb G AW/DMCS with copper(II) chloride was effective for removal of amines from gas-chromatographic streams, but it did not affect the chromatographic behavior of nonamine compounds. By using pre-columns packed with the abstractor packing, solventless chromatograms were obtained for samples in pyridine. A method was developed for determining haloforms in drinking water by sorption of the haloforms on columns packed with acetylated XAD-2. A pre-column of the abstractor packing was used to remove the pyridine solvent from the samples containing the haloforms concentrated from waters. Detection limits for the four chloro-, bromo- haloforms in a 100-ml water sample using an electron capture detector were below 1 ppB. Addition of ascorbic acid to chlorinated waters was effective for stopping the production of haloforms. Design of the inlet allowed samples to be introduced to the capillary column in a Tracor model 550 gas chromatograph with or without splitting of the carrier-gas stream. An exit splitter was implemented that carried the effluent from the capillary column to two detectors. The capillary-column system was applied to the analysis of trace components in complex mixtures. Small columns packed with Florisil were used to fractionate mixtures of organic compounds by gravity-flow liquid chromatography. Three fractions of organic compounds were collected from the Florisil columns. The recovery and elution behavior of many organic compounds was investigated. Organic compounds from fifteen waters were fractionated on Florisil.

Random close packing in protein cores

OpenAIRE

Gaines, Jennifer C.; Smith, W. Wendell; Regan, Lynne; O'Hern, Corey S.

2015-01-01

Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions $\\phi \\approx 0.75$, a value that is similar to close packing equal-sized spheres. A limitation of these analyses was the use of `extended atom' models, rather than the more physically accurate `explicit hydrogen' model. The validity of using the explicit hydrogen model is proved by its ability to predict the side chain dihedral angle distributions obs...

Packing Density Approach for Sustainable Development of Concrete

Directory of Open Access Journals (Sweden)

Sudarshan Dattatraya KORE

2017-12-01

Full Text Available This paper deals with the details of optimized mix design for normal strength concrete using particle packing density method. Also the concrete mixes were designed as per BIS: 10262-2009. Different water-cement ratios were used and kept same in both design methods. An attempt has been made to obtain sustainable and cost effective concrete product by use of particle packing density method. The parameters such as workability, compressive strength, cost analysis and carbon di oxide emission were discussed. The results of the study showed that, the compressive strength of the concrete produced by packing density method are closer to that of design compressive strength of BIS code method. By adopting the packing density method for design of concrete mixes, resulted in 11% cost saving with 12% reduction in carbon di oxide emission.

Packing Nonspherical Particles: All Shapes Are Not Created Equal

Science.gov (United States)

Torquato, Salvatore

2012-02-01

Over the past decade there has been increasing interest in the effects of particle shape on the characteristics of dense particle packings, since deviations from sphericity can lead to more realistic models of granular media, nanostructured materials, and tissue architecture. It is clear the that the broken rotational symmetry of a nonspherical particle is a crucial aspect in determining its resulting packing characteristics, but given the infinite variety of possible shapes (ellipsoids, superballs, regular and irregular polyhedra, etc.) it is desirable to formulate packing organizing principles based the particle shape. Such principles are beginning to be elucidated; see Refs. 1 and 2 and references therein. Depending upon whether the particle has central symmetry, inequivalent principle axes, and smooth or flat surfaces, we can describe the nature of its densest packing (which is typically periodic) as well as its disordered jammed states (which may or may not be isostatic). Changing the shape of a particle can dramatically alter its packing attributes. This tunability capability via particle shape could be used to tailor many-particle systems (e.g., colloids and granular media) to have designed crystal, liquid and glassy states. [4pt] [1] S. Torquato and F. H. Stillinger, ``Jammed Hard-Particle Packings: From Kepler to Bernal and Beyond," Rev. Modern Phys. 82, 2633 (2010). [0pt] [2] Y. Jiao and S. Torquato, Communication: ``A Packing of Truncated Tetrahedra That Nearly Fills All of Space and its Melting Properties," J. Chem. Phys. 135, 151101 (2011).

The benefits of hypopharyngeal packing in nasal surgery: a pilot study.

LENUS (Irish Health Repository)

Fennessy, B G

2012-02-01

BACKGROUND: Hypopharyngeal packs are used in nasal surgery to reduce the risk of aspiration and postoperative nausea and vomiting. Side effects associated with their use range from throat pain to retained packs postoperatively. AIM: To evaluate, as a pilot study, postoperative nausea\\/vomiting and throat pain scores for patients undergoing nasal surgery in whom a wet or dry hypopharyngeal pack was placed compared with patients who received no packing. METHODS: A randomized, double-blind prospective trial in a general ENT unit. RESULTS: The study failed to show a statistically significant difference between the three groups in terms of their postoperative nausea\\/vomiting and throat pain scores at 2 and 6 h postoperatively. This is the first study in which dry packs have been compared with wet and absent packs. CONCLUSION: Based on our findings, the authors recommend against placing hypopharyngeal packs for the purpose of preventing postoperative nausea and vomiting.

Granular packings with moving side walls

International Nuclear Information System (INIS)

Landry, James W.; Grest, Gary Stephen

2004-01-01

The effects of movement of the side walls of a confined granular packing are studied by discrete element, molecular dynamics simulations. The dynamical evolution of the stress is studied as a function of wall movement both in the direction of gravity as well as opposite to it. For all wall velocities explored, the stress in the final state of the system after wall movement is fundamentally different from the original state obtained by pouring particles into the container and letting them settle under the influence of gravity. The original packing possesses a hydrostaticlike region at the top of the container which crosses over to a depth-independent stress. As the walls are moved in the direction opposite to gravity, the saturation stress first reaches a minimum value independent of the wall velocity, then increases to a steady-state value dependent on the wall velocity. After wall movement ceases and the packing reaches equilibrium, the stress profile fits the classic Janssen form for high wall velocities, while some deviations remain for low wall velocities. The wall movement greatly increases the number of particle-wall and particle-particle forces at the Coulomb criterion. Varying the wall velocity has only small effects on the particle structure of the final packing so long as the walls travel a similar distance.

Development of spent salt treatment technology by zeolite column system. Performance evaluation of zeolite column

International Nuclear Information System (INIS)

Miura, Hidenori; Uozumi, Koichi

2009-01-01

At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)

7 CFR 906.340 - Container, pack, and container marking regulations.

Science.gov (United States)

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Container, pack, and container marking regulations... AGRICULTURE ORANGES AND GRAPEFRUIT GROWN IN LOWER RIO GRANDE VALLEY IN TEXAS Container and Pack Requirements § 906.340 Container, pack, and container marking regulations. (a) No handler shall handle any variety of...

cellPACK: a virtual mesoscope to model and visualize structural systems biology.

Science.gov (United States)

Johnson, Graham T; Autin, Ludovic; Al-Alusi, Mostafa; Goodsell, David S; Sanner, Michel F; Olson, Arthur J

2015-01-01

cellPACK assembles computational models of the biological mesoscale, an intermediate scale (10-100 nm) between molecular and cellular biology scales. cellPACK's modular architecture unites existing and novel packing algorithms to generate, visualize and analyze comprehensive three-dimensional models of complex biological environments that integrate data from multiple experimental systems biology and structural biology sources. cellPACK is available as open-source code, with tools for validation of models and with 'recipes' and models for five biological systems: blood plasma, cytoplasm, synaptic vesicles, HIV and a mycoplasma cell. We have applied cellPACK to model distributions of HIV envelope protein to test several hypotheses for consistency with experimental observations. Biologists, educators and outreach specialists can interact with cellPACK models, develop new recipes and perform packing experiments through scripting and graphical user interfaces at http://cellPACK.org/.

Homometrism in close-packed structures

International Nuclear Information System (INIS)

Mardix, S.

1990-01-01

Homometric structures are non-congruent structures having identical X-ray intensity distributions. It has so far been assumed that such structures, while theoretically interesting, would not be realized in practice. Homometrism in close-packed structures is shown to be a realistic possibility. Some general rules applicable to homometric pairs are presented; it is shown that an infinite number of them can be derived from one-dimensional homometric pairs. An exhaustive search of close-packed structures with periods of up to 26 reveals that the smallest period of a homometric pair is 15 and that their number increases rapidly with the period. Homometrism in polytypic structures is further discussed. (orig.)

Avoidance of cigarette pack health warnings among regular cigarette smokers.

Science.gov (United States)

Maynard, Olivia M; Attwood, Angela; O'Brien, Laura; Brooks, Sabrina; Hedge, Craig; Leonards, Ute; Munafò, Marcus R

2014-03-01

Previous research with adults and adolescents indicates that plain cigarette packs increase visual attention to health warnings among non-smokers and non-regular smokers, but not among regular smokers. This may be because regular smokers: (1) are familiar with the health warnings, (2) preferentially attend to branding, or (3) actively avoid health warnings. We sought to distinguish between these explanations using eye-tracking technology. A convenience sample of 30 adult dependent smokers participated in an eye-tracking study. Participants viewed branded, plain and blank packs of cigarettes with familiar and unfamiliar health warnings. The number of fixations to health warnings and branding on the different pack types were recorded. Analysis of variance indicated that regular smokers were biased towards fixating the branding rather than the health warning on all three pack types. This bias was smaller, but still evident, for blank packs, where smokers preferentially attended the blank region over the health warnings. Time-course analysis showed that for branded and plain packs, attention was preferentially directed to the branding location for the entire 10s of the stimulus presentation, while for blank packs this occurred for the last 8s of the stimulus presentation. Familiarity with health warnings had no effect on eye gaze location. Smokers actively avoid cigarette pack health warnings, and this remains the case even in the absence of salient branding information. Smokers may have learned to divert their attention away from cigarette pack health warnings. These findings have implications for cigarette packaging and health warning policy. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

The investigation of cooling tower packing in various arrangements

International Nuclear Information System (INIS)

Golshayshi, H.R.; Missenden, J.F.

1998-01-01

The effect of form with corrugated packing on heat transfer and pressure drop characteristics in atmospheric cooling towers has been studied experimentally. The results showed that the heat transfer coefficient decreased with increase in packing pitch and increase in the ratio of rib pitch to rib height. Friction factors were expressed by a dimensional equation which included pitch and distance between the packings, for both smooth and rough surface. From these results, the relationship between packing heat transfer coefficient and pressure drop was deduced. The correlations were verified with additional experimental data taken with 1.1,P/D p /e 5 . This provides a useful semi experimental relation, in the area generally lacking in design and performance data. (author)

Dynamic chemical characteristics of soil solution after pig manure application: a column study.

Science.gov (United States)

Hao, Xiuzhen; Zhou, Dongmei; Sun, Lei; Li, Lianzhen; Zhang, Hailin

2008-06-01

When manures from intensive livestock operations are applied to agricultural or vegetable fields at a high rate, large amounts of salts and metals will be introduced into soils. Using a column leaching experiment, this study assessed the leaching potential of the downward movement of Cu and Zn as well as some salt ions after an intensive farm pig manure at rates of 0%, 5% and 10% (w/w) were applied to the top 20 cm of two different textured soils (G soil -sandy loam soil; H soil-silty clay loam soil), and investigated the growth of amaranth and Cu and Zn transfer from soil to amaranth (Amaranthus tricolor). Soil solutions were obtained at 20, 40 and 60 cm depth of the packed column and analyzed for pH, electrical conductivity (EC), dissolved organic matter (DOC) and Cu and Zn concentrations. The results indicated that application of pig manure containing Cu and Zn to sandy loam soil might cause higher leaching and uptake risk than silty clay loam soil, especially at high application rates. And manure amendment at 5% and 10% significantly decreased the biomass of amaranth, in which the salt impact rather than Cu and Zn toxicity from manures played more important role in amaranth growth. Thus the farmer should avoid application the high rate of pig manure containing metal and salt to soil at a time, especially in sandy soil.

Integrality gap analysis for bin packing games

NARCIS (Netherlands)

Kern, Walter; Qui, X.

A cooperative bin packing game is an $N$-person game, where the player set $N$ consists of $k$ bins of capacity 1 each and $n$ items of sizes $a_1,\\dots,a_n$. The value $v(S)$ of a coalition $S$ of players is defined to be the maximum total size of items in $S$ that can be packed into the bins of

Investigation of hydrodynamic behavior of a pilot-scale trickle bed reactor packed with hydrophobic catalyst using radiotracer technique

International Nuclear Information System (INIS)

Kumar, Rajesh; Mohan, Sadhana; Pant, H.J.; Sharma, V.K.; Mahajani, S.M.

2010-01-01

Exchange of isotopes of hydrogen between aqueous phase and hydrogen gas is one of the most efficient methods for separation of hydrogen isotopes and is commonly used for production of heavy water or removal of tritium from tritiated water effluents. The isotope exchange reaction can be effectively executed in a counter-current trickle bed reactor (TBR) packed with a novel metal (Pt, Pd, Ni) based hydrophobic catalyst as the conventional novel metal based hydrophilic catalysts become ineffective after they come in contact with liquid effluents. The overall exchange reaction in the TBR mainly consists of a gas-liquid mass transfer process that transfers reactants from liquid to gaseous phase followed by an isotopic exchange reaction between the reactants in gaseous phase in presence of a solid hydrophobic catalyst. However, due to water repellent nature of the catalyst, poor liquid distribution in the reactor is normally observed that deteriorates the gas-liquid mass transfer. Therefore, it was thought that if a mixture of hydrophobic catalyst and a suitable hydrophilic mass transfer packing is used to fill the TBR column then, it can improve the distribution or mixing of the liquid and gas phase and thus improve the gas-liquid mass transfer and overall performance of the reactor and needs to be confirmed

Gravel packing dual zones in one trip reduces offshore completion time

International Nuclear Information System (INIS)

Brannon, D.H.; Harrison, D.T.; van Sickle, E.W.

1991-01-01

A single trip, dual-zone gravel pack system was used to successfully gravel pack two wells on Green Canyon platform 52 A in the Gulf of Mexico. An average 56 hours was saved on each well, representing reductions of about 25% in completion time and 26% in completion cost per well. Time-sensitive costs had the largest impact on Green Canyon 52 A final well completion cost; therefore, new technology or more efficient operations were required to minimize completion time. One way to enhance project economics was to gravel pack two separate zones in one trip. In this paper, four objectives are addressed during development of a single trip tool to gravel pack the stacked zones of the Marquette project. These were time and cost reduction, removal of loss circulation material (LCM) prior to gravel packing, zone isolation during gravel packing and use of conventional gravel placement techniques. The design requirement that all LCM (salt and/or viscous polymer pills), perforation debris and formation sand be removed from the wellbore prior to gravel packing was accomplished by incorporating a washdown feature that allows circulation at the bottom of the gravel pack assembly prior to landing in the sump packer

Disordered strictly jammed binary sphere packings attain an anomalously large range of densities

Science.gov (United States)

Hopkins, Adam B.; Stillinger, Frank H.; Torquato, Salvatore

2013-08-01

Previous attempts to simulate disordered binary sphere packings have been limited in producing mechanically stable, isostatic packings across a broad spectrum of packing fractions. Here we report that disordered strictly jammed binary packings (packings that remain mechanically stable under general shear deformations and compressions) can be produced with an anomalously large range of average packing fractions 0.634≤ϕ≤0.829 for small to large sphere radius ratios α restricted to α≥0.100. Surprisingly, this range of average packing fractions is obtained for packings containing a subset of spheres (called the backbone) that are exactly strictly jammed, exactly isostatic, and also generated from random initial conditions. Additionally, the average packing fractions of these packings at certain α and small sphere relative number concentrations x approach those of the corresponding densest known ordered packings. These findings suggest for entropic reasons that these high-density disordered packings should be good glass formers and that they may be easy to prepare experimentally. We also identify an unusual feature of the packing fraction of jammed backbones (packings with rattlers excluded). The backbone packing fraction is about 0.624 over the majority of the α-x plane, even when large numbers of small spheres are present in the backbone. Over the (relatively small) area of the α-x plane where the backbone is not roughly constant, we find that backbone packing fractions range from about 0.606 to 0.829, with the volume of rattler spheres comprising between 1.6% and 26.9% of total sphere volume. To generate isostatic strictly jammed packings, we use an implementation of the Torquato-Jiao sequential linear programming algorithm [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.82.061302 82, 061302 (2010)], which is an efficient producer of inherent structures (mechanically stable configurations at the local maxima in the density landscape). The identification and

SimPackJ/S: a web-oriented toolkit for discrete event simulation

Science.gov (United States)

Park, Minho; Fishwick, Paul A.

2002-07-01

SimPackJ/S is the JavaScript and Java version of SimPack, which means SimPackJ/S is a collection of JavaScript and Java libraries and executable programs for computer simulations. The main purpose of creating SimPackJ/S is that we allow existing SimPack users to expand simulation areas and provide future users with a freeware simulation toolkit to simulate and model a system in web environments. One of the goals for this paper is to introduce SimPackJ/S. The other goal is to propose translation rules for converting C to JavaScript and Java. Most parts demonstrate the translation rules with examples. In addition, we discuss a 3D dynamic system model and overview an approach to 3D dynamic systems using SimPackJ/S. We explain an interface between SimPackJ/S and the 3D language--Virtual Reality Modeling Language (VRML). This paper documents how to translate C to JavaScript and Java and how to utilize SimPackJ/S within a 3D web environment.

Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices

OpenAIRE

Ke, Yonggang; Voigt, Niels V.; Gothelf, Kurt V.; Shih, William M.

2012-01-01

“Scaffolded DNA origami” has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry. Here we report successful folding of multilayer DNA origami with helices arranged on a close-packed hexagonal lattice. This arrangement yields a higher density of helical packing and therefore higher r...

Improved Erythrocyte Osmotic Fragility and Packed Cell Volume ...

African Journals Online (AJOL)

Improved Erythrocyte Osmotic Fragility and Packed Cell Volume following administration of Aloe barbadensis Juice Extract in Rats. ... Abstract. Aloe barbadensis is a popular house plant that has a long history of a multipurpose folk remedy. ... Keywords: osmotic fragility, packed cell volume, haemoglobin, Aloe vera ...

The Tobacco Pack Surveillance System: A Protocol for Assessing Health Warning Compliance, Design Features, and Appeals of Tobacco Packs Sold in Low- and Middle-Income Countries.

Science.gov (United States)

Smith, Katherine; Washington, Carmen; Brown, Jennifer; Vadnais, Alison; Kroart, Laura; Ferguson, Jacqueline; Cohen, Joanna

2015-01-01

Tobacco remains the world's leading preventable cause of death, with the majority of tobacco-caused deaths occurring in low- and middle-income countries. The first global health treaty, the Framework Convention on Tobacco Control (FCTC), outlines a set of policy initiatives that have been demonstrated as effective in reducing tobacco use. Article 11 of the FCTC focuses on using the tobacco package to communicate tobacco-caused harms; it also seeks to restrict the delivery of misleading information about the product on the pack. The objective of this study was to establish a surveillance system for tobacco packs in the 14 low- and middle-income countries with the greatest number of smokers. The Tobacco Pack Surveillance System (TPackSS) monitors whether required health warnings on tobacco packages are being implemented as intended, and identifies pack designs and appeals that might violate or detract from the communication of harm-related information and undermine the impact of a country's tobacco packaging laws. The protocol outlined is intended to be applicable or adaptable for surveillance efforts in other countries. Tobacco packs were collected in 14 countries during 2013. The intention was, to the extent possible, to construct a census of "unique" pack presentations available for purchase in each country. The TPackSS team partnered with in-country field staff to implement a standardized protocol for acquiring packs from 36 diverse neighborhoods across three cities in each country. At the time of purchase, data on price and place of acquisition of each pack was recorded. The field staff, according to a standardized protocol, then photographed packs before they were shipped to the United States for coding and archiving. Each pack was coded for compliance with the country-specific health warning label laws, as well as for key design features of the pack and appeals of the branding elements. The coding protocols were developed based upon prior research, expert

Application of four novel fungal strains to remove arsenic from contaminated water in batch and column modes.

Science.gov (United States)

Jaiswal, Virendra; Saxena, Sangeeta; Kaur, Ispreet; Dubey, Priya; Nand, Sampurna; Naseem, Mariya; Singh, Suman B; Srivastava, Pankaj Kumar; Barik, Saroj Kanta

2018-08-15

Immobilized biomass of novel indigenous fungal strains FNBR_3, FNBR_6, FNBR_13, and FNBR_19 were evaluated for arsenic (As) removal from aqueous solution. Alginate beads containing 0.1 g biomass were used in a batch experiment (200 mg l -1 As; pH 6). Biosorption equilibrium established in first 2 h with As adsorption (mg g -1 ) as 70, 68, 113 and 90 by FNBR_3, FNBR_6, FNBR_13 and FNBR_19, respectively. The equilibrium was fitted to the Langmuir model (r 2  = 0. 90-0.97). The absorption kinetic followed the pseudo second order. Changes in the surface of fungal cells and intracellular As-uptake by fungal biomass were also confirmed by scanning electron microscopy combined with X-ray energy dispersive spectrometer. The presence of different functional groups on fungal cells capable of As-binding was investigated by FTIR. The As-removal by immobilized fungal beads tested in the packed columns also. The As-adsorption by biomass (qe as mg g -1 ) were recorded as 59.5 (FNBR_3 and FNBR_6), 74.8 (FNBR_13), and 66.3 (FNBR_19) in the column and validated by Thomas model. This is the first report concerning the arsenic removal by immobilized biomass of these novel fungal strains from aqueous solution both in batch and column studies with a prospect of their further industrial application. Copyright © 2018 Elsevier B.V. All rights reserved.

Scottish young people's perceptions of standardised packs - a qualitative study

Directory of Open Access Journals (Sweden)

Andy Macgregor

2018-03-01

Full Text Available Background Standardised cigarette packs were introduced into the UK in May 2016. Retailers could sell old stock until May 2017 after which only the sale of cigarettes and tobacco in standardised packs was allowed. As in Australia, pack shape, colour, opening mechanism and font are regulated, together with the size and position of health warnings and number of cigarettes in a pack. This paper explores Scottish young people's awareness of and views about standardised packs in Spring 2017. Methods The DISPLAY study is a five year study established to evaluate the national tobacco point-of sale (POS promotions ban in four communities in Scotland. This paper is based on the qualitative component, annual focus groups carried out with Secondary 2 (13 year olds and Secondary 4 (15 year olds students in four secondary schools. 16 groups (82 students convened in February - March 2017 explored students' perceptions of standardised packaging. Results There was a high level of awareness of standardised packs prior to their full implementation. Smokers had bought them, and they and other participants had seen them in possession of friends and family members, and in litter. Participants' views of the new packaging were generally negative, described as unappealing and depressing, particularly the pictorial health warnings. Packs were compared unfavourably with previous non-standardised versions. However, there was no consensus on their likely impact. Some participants argued that their impact would be widespread, while others thought that any impact would be confined to young non/occasional smokers and that established smokers would be unaffected. Conclusions In early 2017 young people in Scotland had high awareness and knowledge of standardised tobacco packs before their full implementation. Despite differing views about their likely impact on youth smoking, participants irrespective of smoking status overwhelmingly regarded them as unattractive and less

Metallic witness packs for behind-armour debris characterization

NARCIS (Netherlands)

Verolme, J.L.; Szymczak, M.; Broos, J.P.F.

1999-01-01

For the experimental characterization of behind-armour debris so-called metallic witness packs can be used. A metallic witness pack consists of an array of metallic plates interspaced by polystyrene foam sheets. To quantify the fragment mass and velocity from the corresponding hole area and position

Consistency Check for the Bin Packing Constraint Revisited

Science.gov (United States)

Dupuis, Julien; Schaus, Pierre; Deville, Yves

The bin packing problem (BP) consists in finding the minimum number of bins necessary to pack a set of items so that the total size of the items in each bin does not exceed the bin capacity C. The bin capacity is common for all the bins.

Performance evaluation of a rectifier column using gamma column scanning

Directory of Open Access Journals (Sweden)

Aquino Denis D.

2017-12-01

Full Text Available Rectifier columns are considered to be a critical component in petroleum refineries and petrochemical processing installations as they are able to affect the overall performance of these facilities. It is deemed necessary to monitor the operational conditions of such vessels to optimize processes and prevent anomalies which could pose undesired consequences on product quality that might lead to huge financial losses. A rectifier column was subjected to gamma scanning using a 10-mCi Co-60 source and a 2-inch-long detector in tandem. Several scans were performed to gather information on the operating conditions of the column under different sets of operating parameters. The scan profiles revealed unexpected decreases in the radiation intensity at vapour levels between trays 2 and 3, and between trays 4 and 5. Flooding also occurred during several scans which could be attributed to parametric settings.

A new approach for bioethanol production from sugarcane bagasse using hydrodynamic cavitation assisted-pretreatment and column reactors.

Science.gov (United States)

Terán Hilares, Ruly; Kamoei, Douglas Viana; Ahmed, Muhammad Ajaz; da Silva, Silvio Silvério; Han, Jong-In; Santos, Júlio César Dos

2018-05-01

Hydrodynamic cavitation (HC) was adopted to assist alkaline-hydrogen peroxide pretreatment of sugarcane bagasse (SCB). In the following condition: 0.29 M of NaOH, 0.78% (v/v) of H 2 O 2 , 9.95 min of process time and 3 bar of inlet pressure, 95.4% of digestibility of cellulosic fraction was achieved. To take the best use of the pretreated biomass, the overall process was intensified by way of employing a packed bed flow-through column reactor and thus enabling to handle a high solid loading of 20%, thereby leading to cellulose and hemicellulose conversions to 74.7% and 75%, respectively. In the fermentation step, a bubble column reactor was introduced to maximize ethanol production from the pretreated SCB by Scheffersomyces stipitis NRRL-Y7124, resulting in 31.50 g/L of ethanol, 0.49 g/g of ethanol yield and 0.68 g/L.h of productivity. All this showed that our HC-assisted NaOH-H 2 O 2 pretreatment strategy along with the process intensification approach might offer an option for SCB-based biorefineries. Copyright © 2018 Elsevier B.V. All rights reserved.

Non-Fickian dispersive transport of strontium in laboratory-scale columns: Modelling and evaluation

Science.gov (United States)

Liu, Dongxu; Jivkov, Andrey P.; Wang, Lichun; Si, Gaohua; Yu, Jing

2017-06-01

In the context of environmental remediation of contaminated sites and safety assessment of nuclear waste disposal in the near-surface zone, we investigate the leaching and non-Fickian dispersive migration with sorption of strontium (mocking strontium-90) through columns packed with sand and clay. Analysis is based on breakthrough curves (BTCs) from column experiments, which simulated rainfall infiltration and source term release scenario, rather than applying constant tracer solution at the inlet as commonly used. BTCs are re-evaluated and transport parameters are estimated by inverse modelling using two approaches: (1) equilibrium advection-dispersion equation (ADE); and (2) continuous time random walk (CTRW). Firstly, based on a method for calculating leach concentration, the inlet condition with an exponential decay input is identified. Secondly, the results show that approximately 39%-58% of Br- and 16%-49% of Sr2+ are eluted from the columns at the end of the breakthrough experiments. This suggests that trapping mechanisms, including diffusion into immobile zones and attachment of tracer on mineral surfaces, are more pronounced for Sr2+ than for Br-. Thirdly, we demonstrate robustness of CTRW-based truncated power-law (TPL) model in capturing non-Fickian reactive transport with 0 2. The non-Fickian dispersion observed experimentally is explained by variations of local flow field from preferential flow paths due to physical heterogeneities. Particularly, the additional sorption process of strontium on clay minerals contributes to the delay of the peak concentration and the tailing features, which leads to an enhanced non-Fickian transport for strontium. Finally, the ADE and CTRW approaches to environmental modelling are evaluated. It is shown that CTRW with a sorption term can describe non-Fickian dispersive transport of strontium at laboratory scale by identifying appropriate parameters, while the traditional ADE with a retardation factor fails to reproduce

Packing frustration in dense confined fluids.

Science.gov (United States)

Nygård, Kim; Sarman, Sten; Kjellander, Roland

2014-09-07

Packing frustration for confined fluids, i.e., the incompatibility between the preferred packing of the fluid particles and the packing constraints imposed by the confining surfaces, is studied for a dense hard-sphere fluid confined between planar hard surfaces at short separations. The detailed mechanism for the frustration is investigated via an analysis of the anisotropic pair distributions of the confined fluid, as obtained from integral equation theory for inhomogeneous fluids at pair correlation level within the anisotropic Percus-Yevick approximation. By examining the mean forces that arise from interparticle collisions around the periphery of each particle in the slit, we calculate the principal components of the mean force for the density profile--each component being the sum of collisional forces on a particle's hemisphere facing either surface. The variations of these components with the slit width give rise to rather intricate changes in the layer structure between the surfaces, but, as shown in this paper, the basis of these variations can be easily understood qualitatively and often also semi-quantitatively. It is found that the ordering of the fluid is in essence governed locally by the packing constraints at each single solid-fluid interface. A simple superposition of forces due to the presence of each surface gives surprisingly good estimates of the density profiles, but there remain nontrivial confinement effects that cannot be explained by superposition, most notably the magnitude of the excess adsorption of particles in the slit relative to bulk.

Evaluation of Type II Fast Packs for Electrostatic Discharge Properties.

Science.gov (United States)

1983-08-01

34 x 8" x 1 3/4") consisting of a reclosable cushioned carrier which mates into an outer fiberboard sleeve. A cushioning insert is used consisting of a... RECLOSABLE CUSHIONED CARRIER TEST LOAD FIGURE 1: Cancel Caddy Pack * CONVOLUTED 4* CUSHIONED I FIGURE 2: Type II Fast Pack (PPP-B-1672) TYPE II FAST PACK

Important notice for Windows 2000 Service Pack 3 computers

CERN Multimedia

The NICE Team

2005-01-01

Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1)) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the ‘Start' button and select ‘Run'. In the new window that open...

Important notice for Windows 2000 Service Pack 3 computers

CERN Multimedia

The NICE Team

2005-01-01

Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1) ) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the ‘Start' button and select ‘Run'. In the new window that opens, type ‘wi...

ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION

International Nuclear Information System (INIS)

Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

2012-01-01

We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 10 21 cm –2 , which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 10 22 cm –2 at z = 0. Using observations of the column density distribution, we argue that the H I-H 2 transition does not cause the turnover at N H I ≈ 10 21 cm –2 but can plausibly explain the turnover at N H I ∼> 10 22 cm –2 . We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ∼ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

A Three-electrode Column for Pd-Catalytic Oxidation of TCE in Groundwater with Automatic pH-regulation and Resistance to Reduced Sulfur Compound Foiling

OpenAIRE

Yuan, Songhu; Chen, Mingjie; Mao, Xuhui; Alshawabkeh, Akram N.

2012-01-01

A hybrid electrolysis and Pd-catalytic oxidation process is evaluated for degradation of trichloroethylene (TCE) in groundwater. A three-electrode, one anode and two cathodes, column is employed to automatically develop a low pH condition in the Pd vicinity and a neutral effluent. Simulated groundwater containing up to 5 mM bicarbonate can be acidified to below pH 4 in the Pd vicinity using a total of 60 mA with 20 mA passing through the third electrode. By packing 2 g of Pd/Al2O3 pellets in ...

Quasi-Dual-Packed-Kerneled Au49 (2,4-DMBT)27 Nanoclusters and the Influence of Kernel Packing on the Electrochemical Gap.

Science.gov (United States)

Liao, Lingwen; Zhuang, Shengli; Wang, Pu; Xu, Yanan; Yan, Nan; Dong, Hongwei; Wang, Chengming; Zhao, Yan; Xia, Nan; Li, Jin; Deng, Haiteng; Pei, Yong; Tian, Shi-Kai; Wu, Zhikun

2017-10-02

Although face-centered cubic (fcc), body-centered cubic (bcc), hexagonal close-packed (hcp), and other structured gold nanoclusters have been reported, it was unclear whether gold nanoclusters with mix-packed (fcc and non-fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. A Au 49 (2,4-DMBT) 27 nanocluster with a shell electron count of 22 has now been been synthesized and structurally resolved by single-crystal X-ray crystallography, which revealed that Au 49 (2,4-DMBT) 27 contains a unique Au 34 kernel consisting of one quasi-fcc-structured Au 21 and one non-fcc-structured Au 13 unit (where 2,4-DMBTH=2,4-dimethylbenzenethiol). Further experiments revealed that the kernel packing greatly influences the electrochemical gap (EG) and the fcc structure has a larger EG than the investigated non-fcc structure. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Packing of equal discs on a parabolic spiral lattice

International Nuclear Information System (INIS)

Xudong, F.; Bursill, L.A.; Julin, P.

1989-01-01

A contact disc model is investigated to determine the most closely-packed parabolic spiral lattice. The most space-efficient packings have divergence angles in agreement with the priority ranking of natural spiral structures

Empirical correlations for axial dispersion coefficient and Peclet number in fixed-bed columns.

Science.gov (United States)

Rastegar, Seyed Omid; Gu, Tingyue

2017-03-24

In this work, a new correlation for the axial dispersion coefficient was obtained using experimental data in the literature for axial dispersion in fixed-bed columns packed with particles. The Chung and Wen correlation, the De Ligny correlation are two popular empirical correlations. However, the former lacks the molecular diffusion term and the latter does not consider bed voidage. The new axial dispersion coefficient correlation in this work was based on additional experimental data in the literature by considering both molecular diffusion and bed voidage. It is more comprehensive and accurate. The Peclet number correlation from the new axial dispersion coefficient correlation on the average leads to 12% lower Peclet number values compared to the values from the Chung and Wen correlation, and in many cases much smaller than those from the De Ligny correlation. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrodynamics of multi-phase packed bed micro-reactors

NARCIS (Netherlands)

Márquez Luzardo, N.M.

2010-01-01

Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the

27 CFR 24.255 - Bottling or packing wine.

Science.gov (United States)

2010-04-01

... in the same tax class when that wine is removed from bond, without benefit of tolerance, when the... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottling or packing wine..., DEPARTMENT OF THE TREASURY LIQUORS WINE Storage, Treatment and Finishing of Wine Bottling, Packing, and...

Compact electron beam focusing column

Science.gov (United States)

Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

2001-12-01

A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

A Capillary Electrochromatographic Microchip Packed with Self-Assembly Colloidal Carboxylic Silica Beads

Energy Technology Data Exchange (ETDEWEB)

Jeon, In Sun; Kim, Shin Seon; Park, Jong Man [Konkuk University, Seoul (Korea, Republic of)

2012-04-15

An electrochromatographic microchip with carboxyl-group-derivatized mono-disperse silica packing was prepared from the corresponding colloidal silica solution by utilizing capillary action and self-assembly behavior. The silica beads in water were primed by the capillary action toward the ends of cross-patterned microchannel on a cyclic olefinic copolymer (COC) substrate. Slow evaporation of water at the front of packing promoted the self-assembled packing of the beads. After thermally binding a cover plate on the chip substrate, reservoirs for sample solutions were fabricated at the ends of the microchannel. The packing at the entrances of the microchannel was silver coated to fix utilizing an electroless silver-plating technique to prevent the erosion of the packed structure caused by the sudden switching of a high voltage DC power source. The electrochromatographic behavior of the microchip was explored and compared to that of the microchip with bare silica packing in basic borate buffer. Electrophoretic migration of Rhodamine B was dominant in the microchip with the carboxyl-derivatized silica packing that resulted in a migration approximated twice as fast, while the reversible adsorption was dominant in the bare silica-packed microchip. Not only the faster migration rates of the negatively charged FITC-derivatives of amino acids but also the different migration due to the charge interaction at the packing surface were observed. The electrochromatographic characteristics were studied in detail and compared with those of the bare silica packed microchip in terms of the packing material, the separation potential, pH of the running buffer, and also the separation channel length

49 CFR 173.121 - Class 3-Assignment of packing group.

Science.gov (United States)

2010-10-01

... packing group shall be determined by applying the following criteria: Packing group Flash point (closed-cup) Initial boiling point I ≤35°C (95 °F) II 35 °C (95 °F) III ≥23 °C, ≤60 °C (≥73 °F, ≤140 °F) >35...-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Definitions Classification, Packing Group Assignments...

The pack size effect: Influence on consumer perceptions of portion sizes

NARCIS (Netherlands)

Hieke, Sophie; Palascha, Aikaterini; Jola, Corinne; Wills, Josephine; Raats, Monique M.

2016-01-01

Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While