Loop Column Research Articles

CARRIER FLOTATION BY CHAR SLIME - WASHING OF ŞIRNAK ASPHALTITE SLIMES

Şırnak asphaltite slime below 200 micron size is processed. The clean coal products of the column flotation are received with mid-products and shale settlements in the modified column cell in the baffled form. The use of hydrocyclone, agglomerate thickener and wash decantation has been a suitable potential method after the driven and internal loop column flotation. With this method, ultrafine sized oily sludges with high efficiency and low solid rate coal washing are provided. It also enabled highly efficient wastewater treatment as a result of separating the oil with czar foam. Therefore, the method applied in this study can be designed as an optimum wastewater treatment technology for the treatment of oily wastewater in the oil and drilling industry. The aeration process in internal loop column flotation with air jet is widely used in lake water treatment and fresh water treatment. In this study, internal loop carrier column flotation, hydrocyclone overflows and agglomeration process are optimized for coal washing and environmental wastewater treatment. The ash and sulfur contents decreased to a level of 48% ash reduction and a 34% sulphur reduction

Biomechanical Characteristics of Light Synthetic Materials for Hernioplasty (Experimental Study)

Importance of the topic. One of the directions of improving hernioplasty efficiency with the use of light synthetic materials is including the strengthening zones in their structure.
 Purpose. To compare functional effectiveness of the light and the light strengthened polypropylene endoprostheses for hernioplasty on the base of studying biomechanical characteristics of anterior abdominal wall tissues after their implantation in experiment.
 Materials and methods. Experimental studies were conducted on 36 rabbits of “chinchilla” breed. All animals were divided into 2 series of experiments. In the first (control) series the light polypropylene endoprosthesis was implanted, while in the second (experimental) series there was used a new cancellated endoprosthesis from monofilamentous polypropylene, consisting of the basic and strengthened zones in the form of horizontally located, alternating with each other monothreads of the higher thickness. Pathomorphological changes and biomechanical properties of the abdominal wall tissues were studied macroscopically in the experiment by implantation of endoprostheses in onlay position on the 7th, 30th and 90th days.
 Results and their discussion. There was proved that in direction of the loop column as well as in the loop row after implantation of the studied materials breaking load increased from the 7th to the 90th day of experiment, that was related to the formation of the connective tissue capsule around materials. The light strengthened endoprosthesis was more durable and stronger in 1,6 times compare to the light analog at all stages of observation. Along the loop column there was no significant difference detected. In both series of experiment in the direction of the loop column as well as in loop row the reduction of sample lengthening took place. Along the loop column indicators of lengthening, characterizing elasticity of the prosthesis aponeurosis, in the series of the light strengthened endoprosthesis were 1,4-1,6 times lower than in its light analog. Along the loop row there was no significant difference of indicators.
 Conclusion. Introduction of the strengthened zones in a light endoprosthesis increases its durability with preservation of the material’s elasticity.

Washcoated Pd/Al2O3 monoliths for the liquid phase hydrodechlorination of dioxins

The catalytic activity and durability of 2wt.% Pd/Al2O3 in powder and washcoated on cordierite monoliths were examined for the liquid phase hydrodechlorination (LPHDC) of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs), also known as dioxins. NaOH was employed as a neutralizing agent, and 2-propanol was used as a hydrogen donor and a solvent. Fresh and spent powder and monolith samples were characterized by elemental analysis, surface area, hydrogen chemisorption, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and transmission electron microscopy/energy dispersive X-ray spectroscopy (TEM/EDX). Three reactor configurations were compared including the slurry and monolith batch reactors as well as the bubble loop column resulting in 100, 70, and 72% sample toxicity reduction, respectively, after 5h of reaction. However, the slurry and monolith batch reactors lead to catalyst sample loss via a filtration process (slurry) and washcoat erosion (monolith batch), as well as rapid deactivation of the powder catalyst samples. The monolith employed in the bubble loop column remained stable and active after four reaction runs. Three preemptive regeneration methods were evaluated on spent monolith catalyst including 2-propanol washing, oxidation/reduction, and reduction. All three procedures reactivated the spent catalyst samples, but the combustion methods proved to be more efficient at eliminating the more stable poisons.

Evidence for a solar coronal thick-target hard X-ray source observed by RHESSI

We study a solar flare hard X-ray (HXR) source observed by the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) in which the HXR emission is almost entirely in a coronal loop so dense as to be collisionally thick at electron energies up to ∼45−60 keV. This contrasts with most events previously reported in which the HXR emission is primarily from the loop footpoints in the collisionally dense chromosphere. In particular, we show that the high loop column densities inferred from the GOES and RHESSI soft X-ray emission measure and the volume of the flare loop are consistent with the coronal thick-target interpretation of the HXR images and spectra. The high column densities observed already at the very beginning of the impulsive phase are explained by chromospheric evaporation during a preflare which, as Nobeyama 17 GHz radio images reveal, took place in the same set of nested loops as the main flare.

A Coronal Thick-Target Interpretation of Two Hard X-Ray Loop Events

We report a new class of solar flare hard X-ray (HXR) sources in which the emission is mainly in a coronal loop so dense as to be collisionally thick at electron energies up to ≳50 keV. In most of the events previously reported, most of the emission is at the dense loop footpoints, although sometimes with a faint high-altitude component. HXR RHESSI data on loop dimensions and nonthermal electron parameters and GOES soft X-ray data on hot loop plasma parameters are used to model coronal thick-target physics for two "discovery" events (2002 April 14 [23:56 UT] and 2002 April 15 [23:05 UT]). We show that loop column densities N are consistent with (1) a nonthermal coronal thick-target interpretation of the HXR image and spectrum; (2) chromospheric evaporation by thermal conduction from the hot loop rather than by electron beam heating; and (3) the hot loop temperature being due to a balance of thick-target collisional heating and (mainly) conductive cooling.

A novel column fermentor having a wetted-wall of perfluorocarbon as an oxygen carrier

A novel loop column fermentor was developed, having a wetted-wall of perfluorocarbon (PFC), which has characteristics of very high gas-dissolving capacity and chemical and biological inertness. Medium was supplied with oxygen through liquid–liquid contact with a PFC liquid film created on the annular wall of the column. PFC at the column bottom was re-oxygenated in a separate aerator and re-circulated. The PFC liquid film on the wall did not only carry oxygen but also gently agitate the medium by downward flow of the PFC film. The fermentor was applied to insect cell culture. The growth characteristics of maximum cell density, specific growth yield, and specific lactate yield indicated that the PFC wetted-wall column fermentor was useful for the cultures of shear-sensitive cells.

The Cytoplasmic Loops between Domains II and III and Domains III and IV in the Skeletal Muscle Dihydropyridine Receptor Bind to a Contiguous Site in the Skeletal Muscle Ryanodine Receptor

Excitation-contraction coupling in skeletal muscle is a result of the interaction between the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (ryanodine receptor or RyR1) and the skeletal muscle L-type Ca2+ channel (dihydropyridine receptor or DHPR). Interactions between RyR1 and DHPR are critical for the depolarization-induced activation of Ca2+ release from the sarcoplasmic reticulum, enhancement of DHPR Ca2+ channel activity, and repolarization-induced inactivation of RyR1. The DHPR III-IV loop was fused to glutathione S-transferase (GST) or His-peptide and used as a protein affinity column for 35S-labeled, in vitro translated fragments from the N-terminal three-fourths of RyR1. RyR1 residues Leu922-Asp1112 bound specifically to the DHPR III-IV loop column, but the corresponding fragment from the cardiac ryanodine receptor (RyR2) did not. Construction of chimeras between RyR1 and RyR2 showed that amino acids Lys954-Asp1112 retained full binding activity, whereas Leu922-Phe1075 had no binding activity. The RyR1 sequence Arg1076-Asp1112, previously shown to interact with the DHPR II-III loop (Leong, P., and MacLennan, D., H. (1998) J. Biol. Chem. 273, 7791-7794), bound to DHPR III-IV loop columns, but with only half the efficiency of binding of the longer RyR1 sequence, Lys954-Asp1112. These data suggest that the site of DHPR III-IV loop interaction contains elements from both the Lys954-Phe1075 and Arg1076-Asp1112 fragments. The presence of 4 +/- 0.4 microM GST-DHPR II-III or 5 +/- 0.1 microM His-peptide-DHPR III-IV was required for half-maximal co-purification of 35S-labeled RyR1 Leu922-Asp1112 on glutathione-Sepharose or Ni2+-nitrilotriacetic acid. Dose-dependent inhibition of 35S-labeled RyR1 Leu922-Asp1112 binding to GST-DHPR II-III and GST-DHPR III-IV by His10-DHPR II-III and His-peptide-DHPR III-IV was observed. These studies indicate that the DHPR II-III and III-IV loops bind to contiguous and possibly overlapping sites on RyR1 between Lys 954 and Asp1112.

A 37-Amino Acid Sequence in the Skeletal Muscle Ryanodine Receptor Interacts with the Cytoplasmic Loop between Domains II and III in the Skeletal Muscle Dihydropyridine Receptor

Interactions between the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (ryanodine receptor or RyR1) and the loop linking domains II and III (II-III loop) of the skeletal muscle L-type Ca2+ channel (dihydropyridine receptor or DHPR) are critical for excitation-contraction coupling in skeletal muscle. The DHPR II-III loop was fused to glutathione S-transferase- or His-peptide and used as a protein affinity column for 35S-labeled in vitro translated fragments from the N-terminal three-fourths of RyR1. RyR1 residues Leu922-Asp1112 bound specifically to the DHPR II-III loop column, but the corresponding fragment from the cardiac ryanodine receptor (RyR2) did not. The use of chimeras between RyR1 and RyR2 localized the interaction to 37 amino acids, Arg1076-Asp1112, in RyR1. The RyR1 922-1112 fragment did not bind to the cardiac DHPR II-III loop but did bind to the skeletal muscle Na+ channel II-III loop. The skeletal DHPR II-III loop double mutant K677E/K682E lost most of its capacity to interact with RyR1, suggesting that two positively charged residues are important in the interaction between RyR and DHPR.

On the prediction of local flow structures in internal loop and bubble column reactors using a two-fluid model

On the prediction of local flow structures in internal loop and bubble column reactors using a two-fluid model

The effect of static mixer on mass transfer in draft tube bubble column and in external loop column

Measurement were carried out for pressure drops, liquid circulation velocities, minimum gas velocities for complete suspension of particles, rates of mass transfer from gas to liquid and from liquid to solid in bubble slurry columns with and without static mixers (motionless mixers). Two types of column, a draft tube bubble column (internal type) and an external loop column (external type), were compared. The static mixers were found to be effective to increase rates of mass transfer when a single nozzle was used as the gas distributor. When an optional pump was used in the external loop column, the mass transfer rate could be enhanced significantly.

Plasma assay of salbutamol by means of high-performance liquid chromatography with amperometric determination using a loop column for injection of plasma extracts. Application to the evaluation of subcutaneous administration of salbutamol.

An isocratic high-performance liquid chromatography method with amperometric detection for the assay of plasma salbutamol is described. The plasma extract is injected into the chromatographic system via a loop column. This insures the purification of the injected extracts and allows a simple and rapid liquid-solid extraction procedure. The good reliability, as shown by the low limit of detection (0.5 ng/ml) and a precision ranging between 5 and 10%, has permitted the investigation of a new mode of administration of salbutamol using a portable subcutaneous infusion pump. Our results show that subcutaneous administration yields plasma levels comparable with those obtained after usual intravenous doses.

Determination of lansoprazole and its metabolites in plasma by high-performance liquid chromatography using a loop column

A high-performance liquid chromatographic method for the simultaneous determination of lansoprazole, a new proton pump inhibitor, and its metabolites in human plasma is described. Lansoprazole, its metabolites and an internal standard were extracted with tert.-butyl methyl ether. Samples were injected using an automatic injector via a loop column, and separation was obtained using a reversed-phase column under isocratic conditions. The absorbance was monitored at 285 and 303 nm. The quantification limit was 2 ng/ml for lansoprazole and 3 or 5 ng/ml for the metabolites. No endogenous compounds were found to interfere. The mean overall recovery was between 75 and 95% for lansoprazole and its metabolites. This method is suitable for pharmacokinetic studies.

Loop-column technique: a new sample clean-up method for the determination of gallopamil from biological matrix

A new sample clean-up method for the HPLC determination of gallopamil from biological matrix has been developed. In this method the loop capillary of the injection valve was replaced by a loop column filled with Nucleosil particles. This technique offers reduced extraction time (<1 min) and high sensitivity with a limit of detection as low as 0.1 ng/ml.

Effects of Coulomb collisions on cyclotron maser and plasma wave growth in magnetic loops

The evolution of nonthermal electrons accelerated in magnetic loops is determined by solving the kinetic equation, including magnetic field convergence and Coulomb collisions in order to determine the effects of these interactions on the induced cyclotron maser and plasma wave growth. It is found that the growth rates are larger and the possibility of cyclotron maser action is stronger for smaller loop column density, for larger magnetic field convergence, for a more isotropic injected electron pitch angle distribution, and for more impulsive acceleration. For modest values of the column density in the coronal portion of a flaring loop, the growth rates of instabilities are significantly reduced, and the reduction is much larger for the cyclotron modes than for the plasma wave modes. The rapid decrease in the growth rates with increasing loop column density suggests that, in flare loops when such phenomena occur, the densities are lower than commonly accepted.

High performance liquid chromatography determination of doxorubicin and daunorubicin in plasma using UV detection and column switching

A method for the determination of doxorubicin and daunorubicin in plasma is described. The plasma is injected directly into a loop column and then washed with water. After switching the injection valve, the sample is separated on a phenyl column using detection at 254 nm. The detection limit is 10 ng/mL, the coefficient of variation is 7% for 100 ng/mL of doxorubicin and 4% for 200 ng/mL of daunorubicin.

Determination of phosphatidylcholine and disaturated phosphatidylcholine content in lung surfactant by high performance liquid chromatography.

A rapid isocratic method for determining the total phosphatidylcholine and disaturated phosphatidylcholine levels in lung surfactant preparations by high performance liquid chromatography (HPLC) is described. The analysis was performed on a 3.9 x 300 mm mu-Porasil column with detection by refractive index. The lipids were eluted with a solvent system of chloroform-acetonitrile-methanol-water-85% phosphoric acid 650:650:500:130:2 (v/v/v/v/v). A 4.6 x 30 mm silica guard column was used in place of an injector loop which served as a sample concentrator and purifier. Phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol, all known components of lung surfactants, were eluted from the loop column and were prevented from reaching the analytical column. Sphingomyelin and lysophosphatidylcholine elute later than the phosphatidylcholines on the analytical column. The method was developed so that phosphatidylcholines elute as a single peak regardless of the fatty acid chain length (C12-C20). When the sample was first oxidized with a potassium permanganate-potassium metaperiodate solution, and potentially interfering oxidation products were removed by extraction into a basic aqueous phase, then only the disaturated phosphatidylcholines were analyzed.

A stability-indicating HPLC assay with on-line clean-up for betamethasone 17-valerate in topical dosage forms

A stability-indicating high-performance liquid Chromatographic method with on-line clean-up has been developed for the analysis of betamethasone 17-valerate in topical dosage forms. A short pre-column containing 10 μm octadecylsilane mounted into the sample loop position of an injection valve was used as the primary clean-up step. The utilization of a diode-array UV detector allowed the quantitative analysis of betamethasone 17-valerate together with its degradation product, betamethasone 21-valerate, as well as the qualitative analysis of these compounds, relevant internal standards and the preservatives chlorocresol and methyl hydroxybenzoate contained in the cream and lotion formulations, respectively. Typically, cream and lotion dosage forms were dissolved in acetonitrile and ointments in tetrahydrofuran, internal standards added and aliquots injected onto the analytical system. Dosage form excipients were retained on the loop column and back-flushed to waste with the aid of a second solvent pump while components of interest were allowed to transfer to the analytical column for quantitative analysis. The method is accurate, precise and stability indicating and permits the rapid on-line analysis of betamethasone 17-valerate from complex topical formulation matrices without prior extractions.

A dynamical model of coronal loops

It is shown that, for MHD equilibrium configurations in the corona, the plasma transport across the magnetic field drives the plasma motion when the plasma resistivity is taken into account, provided that the equilibrium configurations are not force-free and that the pressure and/or density changes radially from the center of the loop column.

On-line HPLC method for clean-up and analysis of hydrocortisone and sulconazole nitrate in a cream

The application of a new on-line high-performance liquid Chromatographic method for the clean-up and analysis of drugs in semi-solid formulations was investigated. A short column of a chemically bonded stationary phase (10 μm octadecylsilane) mounted into the sample loop position of the high pressure injection valve was used as the primary clean-up step. The elution behavior of commonly used cream excipients on the loop column as a function of various combinations of water, methanol and THF was studied using a refractive index detector. Typically, samples of the cream were dissolved in methanol-THF and injected onto the loop column. The drug substances were eluted onto the analytical column with predetermined volumes of the mobile phase. The relatively non-polar cream excipients were retained on the loop column. At this time the injection valve was switched, isolating the loop column and the retained excipients were eluted off to waste with a strong solvent (methanol-THF). Loss of efficiency due to the insertion of the loop column was negligible. This technique was applied to the simultaneous analysis of a corticosteroid (hydrocortisone) and a hydrophobic amine (sulconazole nitrate) in a topical cream formulation.