A new fluid distribution system for scale-flexible expanded bed adsorption

A new fluid distribution system designed for expanded bed adsorption was introduced and studied in a 150-cm diameter column. Based on fluid application through a rotating distributor, it eradicates the need for perforated plates, meshes, or local mixers. The effect of rotation rate on column performance was examined by fluidizing a 30-cm high bed of supports with tap water and introducing pulses of dye or acetone tracer. Linear bed expansion was seen as the superficial fluid velocity was raised from 170 x h(-1) to 450 cm x h(-1) (3000 L x h(-1) to 8000 L x h(-1)), and there was little change in expansion characteristics as distributor rotation rate was increased from 2.5 to 10 rpm. The distributor was observed to generate a flow pattern suitable for expanded bed adsorption when the supports were fluidized at a superficial fluid velocity of 283 cm center dot h(-1) and dye pulses introduced. At a rotation rate of 2.5 rpm, no significant dead zones were observed, and a discrete band was formed that moved up through the bed. Furthermore, the pattern of dye movement could be used to calculate interstitial linear fluid velocities of 460 cm x h(-1) and 572 cm x h(-1) at the column wall and center, respectively, indicating a parabolic flow profile. The distributor rotation rate giving the best operating conditions was found to be 2.5 rpm when the bed was fluidized at a flow velocity of 283 cm x h(-1) and the residence time distribution of acetone tracer examined. Under these conditions, the coefficient of axial dispersion was 6.1 x 10(-6) m(2) x s(-1) and 29 theoretical plates were measured. When the rotation rate was raised to 10 rpm, the coefficient of axial dispersion increased to 8.08 x 10(-6) m(2) x s(-1) and the number of theoretical plates decreased to 22.     

Bulk purification of isochorismic acid by low-pressure octadecyl (C18) reverse-phase liquid chromatography.

Partially purified isochorismate synthase (EC 5.4.99.6) from Klebsiella pneumoniae 62-1 was used to produce bulk quantities (3.4-6.8 mg) of isochorismate from chorismate. A new, preparative, low-pressure liquid chromatographic method for the purification of isochorismate was used; a (1.0 X 13.0 cm) octadecyl (C18) reverse-phase column with a discontinuous, stepped methanol gradient as eluent. The recovery of isochorismate was quantitative and its purity was verified by HPLC using a butyl (C4) reverse-phase column. This chromatographic method is superior to those previously described.     

High-Resolution Performance of Polycaprolactone Functionalized with Guanidinium Ionic Liquid for Gas Chromatography

This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations.     

Evaluation of radial chromatography versus axial chromatography, practical approach

Developments in packing and packing port design of radial columns in recent years have resulted in a claimed significant increase in performance of this process chromatography technology. In this first study, the main chromatographic parameters as efficiency, capacity factor, asymmetry and resolution were evaluated in a unique one-to-one comparison between a 120 ml bed-volume and 6 cm bed length radial chromatography mini-process column against a 50 mm diameter, 6 cm bed height and 120 ml bed-volume axial chromatography column. Radial chromatography showed an increase in efficiency by 31% in the number of plates per meter while the equilibration could be reduced by 0.4-0.5 column volumes. The asymmetry factor for bovine serum albumin in radial chromatography showed a reduction of 20% while the reduction of the asymmetry factor of the smaller protein ovotransferrin decreased even by 46% in comparison to the performance of the comparative axial chromatography column. Therefore in radial chromatography resolution improved up to 20%. The retention volume was similar in both cases. For radial chromatography, the decrease in "width at half height" at Height Equivalent of Theoretical Plates (HETP) measurements was 40% while the decrease of the over-all width of the peak was 27%. For adsorbed/desorbed proteins, the elution peak showed similar results: "width at half height" decreased to 45% while the over-all width of the peak decreased by 28%. The concentration of the non-retained protein in the flow-through (lysozyme), increased by 35% while the concentration of the eluted fraction (serum albumin bovine), increased with 40% in the radial chromatography columns. The better results obtained with the radial column were probably the consequence of the geometrical design of this device (larger inlet surface area and small outlet surface area which concentrate the eluted fraction).     

On the use of size exclusion chromatography for the resolution of mixed amyloid aggregate distributions: I. equilibrium partition models

In this study, we investigated the theoretical potential of size exclusion chromatography (SEC) for resolving mixtures of protein aggregates (of various sizes and shapes) produced in the generation of amyloid fibrils. We present our findings in the form of an equilibrium partition model. We first review the general characteristics of SEC and discuss the physicochemical features affecting solute transport and partition. We then develop new methods for estimating the transport and partition coefficients of protein aggregates on the basis of their molecular dimensions and the SEC column properties. We detail how these calculated properties can be used to estimate the likely resolving power of an SEC column. Model predictions were found to be in general agreement with experimental data gained from the measurement of the elution profile of sheared amyloid fibrils prepared from bovine insulin and passed through a Superose 6 precision SEC column. Our formalism should provide a basic appreciation of the competing factors at work and allow an informed choice to be made for optimal selection of SEC column medium to separate a desired size range of aggregate.     

Practice of solid-phase extraction and protein precipitation in the 96-well format combined with high-performance liquid chromatography–ultraviolet detection for the analysis of drugs in plasma and brain

C₁₈ Empore 96-well extraction disc plates have been employed for the analysis of three drugs with different polarities in plasma in conjunction with HPLC–UV, rufinamide, ICL670 and an anticonvulsant agent (AA1) in an early stage of development. With the most polar compound (AA1), ion-pair extraction at pH 12 was applied. The method developed for the assay of AA1 in plasma was applied to its determination in brain using an Oasis HLB plate following homogenisation in a pH 7.4 buffer and protein precipitation with NaOH–ZnSO₄, thereby saving time for method development. Protein precipitation in the 96-well format with filtration of the precipitate was applied to the determination of ICL670, a highly protein-bound compound (>99.5%), with a good recovery (78%). Reversed-phase chromatography was applied using a short 5 cm column packed with 3 μm particles for the determination of ICL670 and AA1 and two parallel columns (15 cm long) for the determination of rufinamide. The methods were used routinely, one plate per analysis day being processed, resulting in increase in sample throughput and saving in solvents.     

A new meroterpenoid isolated from roots of Ptaeroxylon obliquum Radlk.

The roots of Ptaeroxylon obliquum Radlk. (Rutaceae) afforded a new meroterpenoid, ptaerobliquol, together with chromones, ptaeroxylinol acetate and peucenin, and coumarins, scopoletin and prenyletin. Ptaerobliquol was isolated using centrifugal partition chromatography followed by silica gel column and identified as 7a,8,9,9a,9b,10a-heptahydro-4H-10,10-dimethyl-1,7-dioxa-5-hydroxy-2-hydroxymethylcyclobutyl[1,2,3:3,3a,4]indeno[5,6-a]naphtalen-4-one by extensive NMR and single crystal X-ray analyses. A biosynthetic pathway is proposed for this new compound. Activity of ptaerobliquol toward Toxoplasma gondii was investigated and a moderate activity was found with an IC₅₀ of 5.13 μM.     

Scanning molecular sieve chromatography of interacting protein systems. II. Determination of large zone transport parameters by the difference profile method at low solute concentration

The experimental determination of difference profiles for the study of large zone transport processes by scanning molecular sieve chromatography is described. Using the difference profile method, the progesterone-induced purple glycoprotein of the porcine uterus was found to exist as monomeric units in high ionic environment, with a partition coefficient of 0.269, partition cross-section of 0.488, partition radius of 25 A and a molecular weight of 33500 g mole . The technique was further applied in examining the association-dissociation properties of oxyhemoglobin. In a high tonic environment, the partition coefficient was found to be 0.365 for dimer and the partition cross-section, 0.419; for the tetramer in low ionic strength solution, the partition coefficient was 0.275 and the partition cross-section 0.377, with a dissociation constant of 1.03 x 10(-6) mole/1. This new technique should prove applicable in (1) readily locating the centroid positions of transport boundary profiles at the lowest practicable protein concentration limits, (2) demonstrating the characteristic boundary shape and concentration-dependent centroid position for an interacting solute, (3) determining the axial dispersion coefficient characteristic of solute turbulence within the gel matrix, and (4) distinguishing the boundary between low and high ionic strength solvent phases in the gel column.     

Scanning molecular sieve chromatography of interacting protein systems. II. Determination of large zone transport parameters by the difference profile method at low solute concentration.

The experimental determination of difference profiles for the study of large zone transport processes by scanning molecular sieve chromatography is described. Using the difference profile method, the progesterone-induced purple glycoprotein of the porcine uterus was found to exist as monomeric units in high ionic environment, with a partition coefficient of 0.269, partition cross-section of 0.488, partition radius of 25 A and a molecular weight of 33,500 g/mole. The technique was further applied in examining the association-dissociation properties of oxyhemoglobin. In a high tonic environment, the partition coefficient was found to be 0.365 for dimer and the partition cross-section, 0.419; for the tetramer in low ionic strength solution, the partition coefficient was 0.275 and the partition cross-section 0.377, with a dissociation constant of 1.03 x 10(-6) mole/l. This new technique should prove applicable in (1) readily locating the centroid positions of transport boundary profiles at the lowest practible protein concentration limits, (2) demonstrating the characteristic boundary shape and concentration-dependent centroid position for an interacting solute, (3) determining the axial dispersion coefficient characteristic of solute turbulence within the gel matrix, and (4) distinguishing the boundary between low and high ionic strength solvent phases in the gel column.     

Oxygen diffusion in biological and artificial membranes determined by the fluorochrome pyrene

Quenching of pyrene fluorescence by oxygen was used to determine oxygen diffusion coefficients in phospholipid dispersions and erythrocyte plasma membranes. The fluorescence intensity and lifetime of pyrene in both artificial and natural membranes decreases about 80% in the presence of 1 atm O2, while the fluorescence excitation and emission spectra and the absorption spectrum are unaltered. Assuming the oxygen partition coefficient between membrane and aqueous phase to be 4.4, the diffusion coefficients for oxygen at 37 degrees C are 1.51 X 10(-5) cm2/s in dimyristoyl lecithin vesicles, 9.32 X 10(-6) cm2/s in dipalmitoyl lecithin vesicles, and 7.27 X 10(-6) cm2/s in erythrocyte plasma membranes. The heats of activation for oxygen diffusion are low (less than 3 kcal/degree-mol). A dramatic increase in the diffusion constant occurs at the phase transition of dimyristoyl and dipalmitoyl lecithin, which may result from an increase in either the oxygen diffusion coefficient, partition coefficient, or both. The significance of the change in oxygen diffusion below and above the phase transition for biological membranes is discussed.     

Diffusion and partition of solutes in cartilage under static load

We describe experimental apparatus, methodology and mathematical algorithms to measure diffusion and partition for typical small ionic solutes and inulin (a medium size solute) in statically loaded cartilage. The partition coefficient based on tissue water (K(H(2)O)) of Na(+) increased from 1.8 to 4.5 and for SO(4)(-2) decreased from 0.5 to 0.1, when the applied pressure was raised from zero to 22 atm K(H(2)O) of inulin decreased from 0.3 to 0.05, for an increase in pressure from zero to 11 atm. Our theoretical interpretation of the results is that the partition coefficient can be expressed as a function of fixed charge density (FCD) for both loaded and unloaded cartilage. The partition coefficient shows good agreement with the ideal Gibbs-Donnan equilibrium, particularly when FCD is based on extrafibrillar water (EFW). The diffusion coefficients, D also decreased with an increase in applied pressure; raising the pressure from 0 to 22 atm resulted in the following changes in the values of D: for Na(+) from 2.86 x 10(-6) to 1.51 x 10(-6) cm(2)/s, for SO(4)(-2) from 1.58 x 10(-6) to 7.5 x 10(-7) cm(2)/s, for leucine from 1.69 x 10(-6) to 8.30 x 10(-7) cm(2)/s and for inulin from 1.80 x 10(-7) to 3.30 x 10(-8) cm(2)/s. For the three small solutes (two charged and one neutral) the diffusion coefficient D is highly correlated with the fraction of fluid volume in the tissue. These experimental results show good agreement with the simple model of Mackie and Meares: hence solute charge does not affect the diffusion of small solutes under load. For inulin D & K show some agreement with a modified Ogston model based on two major components, viz., glycosaminoglycans (GAG) and core protein. We conclude that the changes in the partition and diffusion coefficients of small and medium size solutes in statically loaded cartilage can be interpreted as being due to the reduction in hydration and increase in FCD. The change in the latter affects the partition of small ionic solutes and the partition and diffusion of larger molecules. Our results throw light on the ionic environment of chondrocytes in loaded cartilage as well as on the transport of solutes through the matrix.     

Scanning gel chromatography: determination of transport parameters from dynamic profiles measured at low solute concentration

Direct optical scanning of solute boundaries in large zone gel Chromatography experiments provides an accurate means of determining boundary profile shapes and rates of motion. A method has been developed for correcting such boundaries to a constant time frame, eliminating the distortion which arises from finite column scanning rate Centroids or the corrected profiles can be used to determine the partition cross section for the solute of interest The partition cross section and flow rate determine translational motion within the column. The axial dispersion coefficient, L, which characterizes rate of boundary spreading may also be calculated from the profiles. In order to explore these procedures a study of four noninteracting solutes was conducted. Partition cross sections determined from rates of motion of boundary centroids were found to be in good agreement with those determined by the equilibrium saturation method on the same column.In order to explore the lowest concentration limits of the technique and to illustrate the boundary characteristics for a selfassociating solute, a study of carboxyhemoglobin was conducted over a wide concentration range. From measurements at 220 nm the lowest concentration where useful data could be obtained was 2 micrograms per ml (0.12 πM heme) These results establish validity of the procedures used in analyzing the rates of boundary transport and in studying solute transport over a wide range of conditions.     

Evaluation of Matrex cellufine GH 25

The aim of this work was to test a new matrix for group size exclusion chromatography, Matrex cellufine GH 25, and compare it with Sephadex G25 Superfine and Sephadex G25 fine. Matrex cellufine GH 25 showed a better behaviour at high flow rate (792 cm/h) without back-pressure or packing-down. Sephadex G25 superfine showed a limited flow rate (226 cm/h) with both back-pressure and packing-down and Sephades G25 fine allowed running at 792 cm/h but with packing-down fourfold superior to that of Matrex cellufine GH 25. To have the same number of theoretical plates, it was necessary to increase the height of the bed and therefore the volume of the matrix (43%). With Matrex cellufine GH 25, the sample volume was more limited (9% of column volume) than with Sephadex G25 superfine (17%) but was equivalent to Sephadex fine (9%). To have the same elution time as Sephadex G25 superfine, the flow rate had to be increased by a factor 1.7. As Matrex cellufine GH 25 allowed a high flow rate when the volume of the sample was limited to 6% of column volume, its performance is better than that of Sephadex G25.     

Image analysis method for evaluation of specific and non-specific hand contamination

AIMS: To evaluate a quantifying image analysis method for assessing the degree of hand contamination and efficacy of hand washing procedures. METHODS AND RESULTS: Two types of experimental design were used. In one, different concentrations of pure cultures of Escherichia coli, Listeria innocua and Pseudomonas flourescens were applied to hands. In the other, hands were contaminated by handling various raw foods. Imprints of the contaminated palms were made on 24.5 x 24.5 cm agar plates using appropriate agars. After incubation, digital photographs of the plates were analysed using image analysis. In pure culture studies with selective agars, levels from 1 to 10(6) CFU cm(-2) palm could be monitored. For aerobic, mesophilic organisms from raw chicken, levels from 10(3) to 10(6) CFU cm(-2) palm were correlated linearly to image analysis data. CONCLUSIONS: The image analysis of palm imprints made on agar plates was suitable for assessing the degree of contamination from foods on the palms. Sensitivity and specificity depended on the agar used and the type of contamination encountered. SIGNIFICANCE AND IMPACT OF THE STUDY: Data capture by the image analysis method is simple and can be partly automated. Sampling time is short for the person to be tested, which makes it an attractive method for assessing hand hygiene status in larger field trials.     

THEORETICAL DESIGN CONSIDERATIONS AND PHYSIOLOGIC PERFORMANCE CRITERIA FOR AN IMPROVED INTRACORPOREAL (ABDOMINAL) ELECTRICALLY ACTUATED LONG-TERM LEFT VENTRICULAR ASSIST DEVICE ("E-TYPE" ALVAD) OR PARTIAL ARTIFICIAL HEART

Our laboratories are engaged in the design of a clinically-oriented electrically actuated long-term intracorporeal (abdominal) left ventricular assist device ("E-type" ALVAD) or partial artificial heart. This infradiaphragmatic blood pump is designed to be powered by implantable electrical to mechanical energy converter systems. THE FOLLOWING ANALYSES WERE UNDERTAKEN TO: [List: see text] The proposed "E-type" ALVAD should be capable of pumping 4-7 liters per minute at heart rates of 75-100 beats per minute during rest, and 10 liters per minute at rates of 120 beats per minute during moderate exercise. These performance levels should be exceeded with a maximum device stroke volume of 85-90 ml and a mean pump inflow (filling) impedance of 相似文献   

Three New Flavone Glycosides from Drymaria diandra Bl.

In order to find new structural and biologically active compounds, the constituents from the whole plant of Drymaria diandra B1. (Caryophyllaceae) were investigated and three new flavone glycosides,named drymariatins B (1), C (2), and D (3), were isolated by solvent partition, Si gel, sephadex LH-20, and Rp-18 column chromatography. Using spectroscopic methods, including two-dimensional nuclear magnetic resonance analysis, the structures of these compounds were elucidated as 6-C-(2-deoxy-β-D-fucopyranosyl)-5,7,4'-trihydroxyl-flavone, 6-C-(2-deoxy-β-D-fucopyranosyl)-7-O-(β-D-glucopyranosyl)-5,4'-dihydroxylflavone, and 6-C-(3-keto-β-digitoxopyranosyl)-7-O-(β-D-glucopyranosyl)-5,4'-dihydroxyl-flavone.     

Isoelectric focusing in layers of granulated gels. II. Preparative isoelectric focusing.

A method for preparative isoelectric focusing of 0.1-10 g amounts of proteins is described. For anticonvective stabilization of the pH gradient, layers of granulated gels (E.G. Sephadex or Bio-Gel) of variable length, width and thickness were used either on glass plates or in troughs. Load capacity, defined as the amount of protein per ml gel suspension, was determined to be 5-10 mg per ml for total protein, irrespective of the pH range of the carrier ampholytes. For single proteins load capacities of 0.25-1 mg per ml were found for pH 3-10 carrier ampholytes, and 2-4 mg per ml for narrow pH range ampholytes. Experiments on a quartz plate followed by densitometric evaluation in situ at 280 nm have demonstrated that it is possible to proceed from analytical thin-layer isoelectric focusing to preparative separations without loss of resolution, just by changing the dimension of the gel layer and increasing the protein load. Improved resolution which facilitates isolation of isoelectrically homegenious components could be achieved on a 40 cm long separation distance. The geometry of a layer is favourable to heat dissipation and this permits the use of high voltage gradients. Recovery of the focused proteins is high an elution simple. The efficiency of the method is illustrated by examples showing separations of single proteins and protein mixtures.     

Distribution of viral abundance in the reef environment of Key Largo, Florida.

The distribution of viral and microbial abundance in the Key Largo, Fla., reef environment was measured. Viral abundance was measured by transmission electron microscope direct counts and plaque titer on specific bacterial hosts in water and sediment samples from Florida Bay (Blackwater Sound) and along a transect from Key Largo to the outer edge of the reef tract in Key Largo Sanctuary. Water column viral direct counts were highest in Blackwater Sound of Florida Bay (1.2 x 10(7) viruses per ml), decreased to the shelf break (1.7 x 10(6) viruses per ml), and were inversely correlated with salinity (r = -0.97). Viral direct counts in sediment samples ranged from 1.35 x 10(8) to 5.3 x 10(8)/cm(3) of sediment and averaged nearly 2 orders of magnitude greater than counts in the water column. Viral direct counts (both sediment and water column measurements) exceeded plaque titers on marine bacterial hosts (Vibrio natriegens and others) by 7 to 8 orders of magnitude. Water column viral abundance did not correlate with bacterial direct counts or chlorophyll a measurements, and sediment viral parameters did not correlate with water column microbial, viral, or salinity data. Coliphage, which are indicators of fecal pollution, were detected in two water column samples and most sediment samples, yet their concentrations were relatively low (<2 to 15/liter for water column samples, and <2 to 108/cm(3) of sediment). Our findings indicate that viruses are abundant in the Key Largo environment, particularly on the Florida Bay side of Key Largo, and that processes governing their distribution in the water column (i.e., salinity and freshwater input) are independent of those governing their distribution in the sediment environment.     

Three New Flavone Glycosides from Drymaria diandra B1.

In order to find new structural and biologically active compounds, the constituents from the whole plant of Drymaria diandra B1. （Caryophyllaceae） were investigated and three new flavone glycosides, named drymariatins B （1）, C （2）, and D （3）, were isolated by solvent partition, Si gel, sephadex LH-20, and Rp- 18 column chromatography. Using spectroscopic methods, including two-dimensional nuclear magnetic resonance analysis, the structures of these compounds were elucidated as 6-C-（2-deoxy-β-D-fucopyranosyl）- 5,7,4＇-trihydroxyl-flavone, 6-C-（2-deoxy-β-D-fucopyranosyl）-7-O-（β-D-glucopyranosyl）-5,4＇-dibydroxyl- flavone, and 6-C-（3-keto-β-digitoxopyranosyl）-7-O-（β-D-glucopyranosyl）-5,4＇-dihydroxyl-flavone.     

Preparative Electrophoresis of Living Mammalian Cells in a Stationary Ficoll Gradient

An apparatus was designed for the vertical density-gradient electrophoresis of viable mammalian cells. Cultured Chinese hamster cells (M3-1F3) were grown is suspension and layered on top of a 0–10% ficoll gradient which was also an inverse 6.8-5.1% sucrose gradient in phosphate buffer, pB 7.2 and 1Z glucose. A 60-ml vertical gradient of this composition covered the density range 1.04–1.05 g/cm³ over a distance of 15 cm in a 2.3 cm diameter glass column. An electric field of approximately 2.3 V/cm was applied for 5 hr. The cells migrated 4.7 cm during this period. The migration rate was consistent with the cells having an electrophoretic mobility of -1.15 ± 0.20 μm/sec per volt/cm, equal to that determined by microelectrophoresis. The gradient was harvested in 50 fractions after electrophoresis, and the viability of the cells was 75% on the basis of colony formation.