Fluid Handling Research Articles

Physiological or Functional Fluid Spaces

Physiological or Functional Fluid Spaces

Optical multiple-analyte immunosensor for water pollution control

A prototype of a portable optical immunosensor (called river analyser) has been developed. It can be applied for the monitoring of surface water quality. Antibodies carrying a fluorescent label are used for the specific recognition of pollutants, such as frequently applied pesticides. The transduction principle is based on total internal reflection fluorescence (TIRF). The outstanding advantage of the river analyser is, that at least three analytes can be detected simultaneously in one sample. Test cycles and fluid handling are automated and enable unattended measuring.

Pulsed electric field processing of high acid liquid foods: A review

Publisher Summary Pulsed electric field (PEF) is a nonthermal food preservation method using high voltage electric field to kill spoilage microorganisms in foods. PEF treatment maintains flavor, color, taste and nutritional value of foods while destroying microorganisms. PEF is useful in processing liquid foods where the food can flow between two electrodes. The generation of PEF processing requires a pulsed power supply, a series of treatment chambers and a temperature regulating system. Therefore, a PEF system usually consists of a high voltage pulse generator, a treatment chamber and a fluid handling system. To process a product using PEF in a continuous system, the product flows through a series of PEF treatment chambers where it is exposed to the desired electric field strength for a desired amount of time. The pulse generator is capable of converting low voltage electricity into high voltage energy to be stored in capacitors until discharged. Three different shapes of high voltage waveforms can be generated and applied to foods. The three waveforms are square wave, exponential decay and under-damped RCL (resistive capacitive and inductive discharge circuit). High voltage electricity is transferred into the food product in the treatment chambers, which may be designed for either static (batch) or continuous processing.

Comparison of reflectometric interference spectroscopy with other instruments for label-free optical detection.

On the basis of kinetic measurements of biomolecular interactions, a reflectometric interference spectroscopy (RIfS) setup is compared with two commercial instruments. These instruments are based on evanescent wave techniques, surface plasmon resonance (SPR) (represented by BIAcore 2000) and resonant mirror (RM) technique (using IAsys plus). All methods allow a label-free and time-resolved optical detection of biomolecular interaction. These methods are mainly used in biomolecular interaction analysis (BIA). They provide practical techniques for quantifying equilibrium constants and rate constants over several orders of magnitude. The general parameters of the three detectors, namely baseline noise and drift as well as overall sensitivity and limits of detection were compared. The fluid handling and the related implications on the measurements have also been considered. The interaction between thrombine and thrombine inhibitor (TI) was investigated as a test system with the three different methods and the kinetic rate constants were determined and compared. For this TI was immobilized on the surface and binding of thrombine was monitored time-resolved. Determination of the kinetic rate constants could prove that the RIfS set-up is comparable with SPR using BIAcore 2000 and RM technique represented by IAsys plus.

Covalent bound sensing layers on surface acoustic wave (SAW) biosensors

This paper reports on the development of immunosensors based on commercially available surface acoustic wave (SAW) devices working at 380 MHz. Approaches for coating the sensor surface with a sensing layer of receptive biomolecules are presented and discussed. It was found that the sensitivity strongly relates to the immobilization method. Additionally, the sensitivity can be influenced by the density of accessible biomolecules on the active sensing area. Usually, by most of the standard immobilization procedures, two-dimensional layers of receptive biomolecules are obtained. We present a three-dimensional layer, which provides a higher absolute amount of recognition molecules. A dextran layer is photoimmobilized to the sensor surface and the recognition molecules are covalently embedded into the dextran matrix. The feasibility of specific immunosensing is investigated using SAW sensors connected to a fluid handling system.

Green, safe and simple pump solutions

Fluid handling is a mature technology. Many pumps have long product life cycles and, in a typical year, few new products are being launched. Conversely, the way pumps are applied in process and manufacturing industries evolve with new business realities. AxFlow UK has found that there are some distinct new trends in customer preference.

Pumping equipment for offshore deep water & marginal oilfields

Weir Pumps Ltd has a long history of advances in pumping technology and is at the forefront of developing novel equipment for oil production for both on and offshore installations. Willie Vance, senior project sales engineer at Weir Pumps, looks at some of the latest Downhole Fluid Handling Technologies while below Graham Kent, applications manager at Weir Pumps, provides an overview of developments in water injection technology...

Fluidics cube for biosensor miniaturization.

To create a small, portable, fully automated biosensor, a compact means of fluid handling is required. We designed, manufactured, and tested a "fluidics cube" for such a purpose. This cube, made of thermoplastic, contains reservoirs and channels for liquid samples and reagents and operates without the use of any internal valves or meters; it is a passive fluid circuit that relies on pressure relief vents to control fluid movement. We demonstrate the ability of pressure relief vents to control fluid movement and show how to simply manufacture or modify the cube. Combined with the planar array biosensor developed at the Naval Research Laboratory, it brings us one step closer to realizing our goal of a handheld biosensor capable of analyzing multiple samples for multiple analytes.

Effects of ethanol on the changes in renal fluid and electrolyte handling and kidney morphology induced by long-term chloroquine administration to rats

This study investigated the effects of long-term chloroquine and ethanol administration on renal fluid and electrolyte handling and kidney structure. Male Sprague–Dawley rats were orally administered with chloroquine diphosphate (20 μg kg −1 bw) and/or ethanol (1.6 g kg −1 bw) every third consecutive day for 4 weeks. Urine volume and total urinary outputs of Na + and K + were determined from 24-h samples. For detailed renal studies, rats were subsequently anaesthetised and challenged with a continuous jugular infusion of 0.077 M NaCl at 150 μl min −1 24 h after the last treatment. After a 3-h equilibration period, urine flow, Na + and K + excretion rates were determined over a 4-h period. Plasma concentrations of AVP and aldosterone were measured in unanaesthetised rats and in anaesthetised rats after hypotonic saline infusion. In separate groups, the rats were anaesthetised with an overdose of ether after 4 weeks of treatment and part of the right kidney was quickly collected and routinely processed for light microscopy. Chloroquine decreased Na + excretion and increased plasma aldosterone concentrations in anaesthetised rats. Ethanol alone did not alter urinary Na + outputs or aldosterone levels. Combined chloroquine and ethanol increased renal Na + excretion, but did not affect plasma aldosterone levels. In unanaesthetised animals all treatments increased aldosterone levels by comparison with control rats. Urinary Na + excretion was decreased by separate administration of either chloroquine or ethanol, but increased by combined treatment. Microscopic studies showed that concurrent chloroquine and ethanol administration induced extensive damage of the proximal tubule and collecting ducts cells. The results of this study suggest that alcohol consumption and chloroquine administration could result in diminished renal function possibly due to alteration of renally active hormones or kidney morphology.

Renal electrolyte and fluid handling in the rat following chloroquine and/or ethanol administration

We postulated that chloroquine and/or ethanol affect plasma arginine vasopressin (AVP) concentrations to alter renal function. Therefore, we studied the effects of chloroquine and/or ethanol on plasma AVP concentrations and fluid, urinary Na + and K + outputs in separate groups of anaesthetized Sprague-Dawley (SD) rats challenged with a continuous jugular infusion of 0.077 M NaCl at 150 μl.min −1. After a 3-h equilibration period, vehicle, chloroquine (0.06 μg.min −1), ethanol (2.4 or 24 μg.min −1) or both chloroquine and ethanol were added to the infusate after 1 h (control) for 1 h 20 min (treatment). The animals were switched back to the infusate alone for the final 1 h 40 min recovery periods. Urine flow Na + and K + excretion rates were determined at 20-min intervals over the subsequent 4-h postequilibration period. Blood was collected from separate groups of animals at the end of treatment period or equivalent time for control animals for measurement of plasma aldosterone and AVP concentrations by radioimmunoassay. Simultaneous chloroquine and ethanol infusion significantly (p < 0.01) increased plasma chloroquine concentrations in an ethanol dose-dependent manner by comparison with animals administered chloroquine alone. Chloroquine infusion alone (0.06 μg.min −1) and/or ethanol (2.4 or 24 μg.min −1) elevated plasma AVP concentrations from 9.73 ± 1.64 fmol.l −1 in control rats to 15.65 ± 2.49 fmol.l −1, 17.39 ± 4.21 fmol.l −1, and 33.87 ± 6.18 fmol.l −1, respectively. Separate administration of chloroquine or ethanol at low dose rates increased urinary Na + excretion rates. We conclude that the impairment of renal electrolyte handling associated with chloroquine administration may be exacerbated by ethanol.

Value of lumbar puncture in the diagnosis of genetic metabolic encephalopathies.

Diagnostic testing for genetically determined metabolic disease has for many years relied heavily on the use of generalized screening tests that analyze groups of related compounds in easily accessible peripheral fluids such as plasma and urine. Organic acid profiles in urine and amino acid analysis in plasma are two of the most commonly requested tests; these, together with other protocols that examine peripheral fluids, have been and continue to be invaluable tools. There is, however, an emerging realization that many metabolic encephalopathies do not arise secondary to peripheral metabolic changes but rather have their origins within the central nervous system. In these cases, testing of peripheral fluids might be uninformative. This review is designed to examine the role of cerebrospinal fluid analyses in the investigation of infants and children with undefined encephalopathies. The aims are to review the conditions in which measurement of metabolites in cerebrospinal fluid is critical if a diagnosis is to be made, and to emphasize that considerable forethought is often required to ensure correct collection and handling of cerebrospinal fluid. Thus, fidelity of the diagnostic analytic procedures is maintained. This review will help the pediatric neurologist establish practical diagnostic guidelines that in turn will help in the recognition of recently described conditions. Those conditions can, in general, be identified only after specialized cerebrospinal fluid testing.

Development of immunosensors based on commercially available surface acoustic wave (SAW) devices

In the present paper we report about the development of immunosensors based on commercially available surface acoustic wave (SAW) devices. The SAW devices applied were originally developed for use in modern telecommunications and are thus available as series products at low costs. For biosensing applications the devices must be coated with a shielding layer to prevent corrosion of the aluminum structures in aqueous media. Thin films of polyimide and parylene, respectively, show good shielding properties and were used as a basis for immobilization of receptor molecules. Various approaches to coating the shielded surfaces with receptive biomolecules are presented briefly and discussed. Finally, covalent binding of dextran as an intermediate layer on SAW devices is described. Dextran bonding is achieved by a photoimmobilization process. The aryldiazirine-functionalized bovine serum albumin (T-BSA) serves as a multifunctional light-activated linking agent (photolinker polymer). Dextran and the photolinker are mixed and photobonded to the sensor surface. Essential parameters of the coating procedure are optimized. Immobilization of proteins to the dextran layer via carbodiimide chemistry is demonstrated. The feasibility of specific immunosensing is investigated using SAW sensors connected to a fluid handling system.

Postnatal time frame for renal vulnerability to enalapril in rats.

Angiotensin-converting enzyme inhibition or angiotensin II type 1 receptor blockade in neonatal, but not in weaned, rats induces irreversible renal histologic abnormalities and an impaired urinary concentrating ability. The aim of the present study was to define the postnatal time frame when the rat kidney is vulnerable to an interruption of the renin-angiotensin system. Male Wistar rats received daily injections of enalapril (10 mg/kg, intraperitoneally) during different age intervals within 3 to 24 d,of age. Fluid handling and urinary concentrating ability, renal function under pentobarbital anesthesia, and kidney histology using stereologic techniques were evaluated in adult rats. Enalapril treatment within 3 to 13 d after birth induced abnormalities in renal function and morphology long-term, whereas treatment initiated at 14 d of age did not. The main histologic alterations were papillary atrophy, and a reduction in the volume of tubular epithelial cells in association with an increase in the proportion of interstitium, throughout the cortex and outer medulla. Functionally, the predominant defect was an impairment in urinary concentrating ability, which correlated with the degree of papillary atrophy. In conclusion, the vulnerable age interval for the induction of irreversible renal abnormalities by enalapril was the first 13 d after birth in the rat. This postnatal time span coincides with the completion of nephrogenesis and a period of marked tubular growth and differentiation, suggesting a pivotal role for angiotensin II in these processes.

Enhanced natriuretic response to neutral endopeptidase inhibition in heart-transplant recipients.

Heart-transplant recipients (Htx) generally present with body fluid and sodium handling abnormalities and hypertension. To investigate whether neutral endopeptidase inhibition (NEP-I) increases endogenous atrial natriuretic peptide (ANP) and enhances natriuresis and diuresis after heart transplantation, ecadotril was given orally to 8 control subjects and 8 matched Htx, and levels of volume-regulating hormones and renal water, electrolyte, and cyclic guanosine monophosphate (cGMP) excretions were monitored for 210 minutes. Baseline plasma ANP, brain natriuretic peptide (BNP), and cGMP were elevated in Htx, but renin and aldosterone, like urinary parameters, did not differ between groups. NEP-I increased plasma ANP (Htx, 20.6+/-2.3 to 33.2+/-5.9 pmol/L, P<0.01; controls, 7.7+/-1. 2 to 10.6+/-2.6 pmol/L) and cGMP, but not BNP. Renin decreased similarly in both groups, whereas aldosterone decreased significantly only in Htx. Enhanced urinary sodium (1650+/-370% versus 450+/-150%, P=0.01), cGMP, and water excretions were observed in Htx and urinary cGMP positively correlated with natriuresis in 6 of the Htx subjects. Consistent with a normal circadian rhythm of blood pressure, without excluding a possible effect of NEP-I, mean systemic blood pressure increased similarly in both groups at the end of the study (6.9+/-2.0% versus 7.4+/-2.8% in controls and Htx). Thus, systemic hypertension, mild renal impairment, and raised plasma ANP levels are possible contributory factors in the enhanced natriuresis and diuresis with NEP-I in Htx. These results support a physiological role for the cardiac hormone after heart transplantation and suggest that long-term studies may be useful to determine the potential of NEP-I in the treatment of sodium retention and water retention after heart transplantation.

The Use of Lithium Clearance Measurements as an Estimate of Glomerulo-Tubular Function

Lithium clearance measurements are based on the observation that lithium undergoes isoosmotic reabsorption in the proximal renal tubule to the same extent as salt and water, but undergoes neither reabsorption nor secretion elsewhere in the nephron. Consequently, lithium clearance values estimate the delivery of isoosmotic fluid to the loop of Henle and hence provide an assessment of proximal tubular reabsorption of isoosmotic fluid. If sodium clearance and urinary flow rate are also measured, then this allows the derivation of a number of parameters relating to both the absolute and relative renal handling of isoosmotic fluid in the proximal and distal regions of the kidney. Consequently, lithium clearance techniques can be used in both experimental and clinical studies to evaluate glomerulo-tubular function and provide information regarding the handling of sodium and water by the proximal and distal nephron in both health and disease. The use of lithium clearance measurements in the assessment of glomerulo-tubular function in patients treated with rIL2 for colorectal cancer is described and its application to both drug-induced toxicity and other disease states discussed.

Mechanisms of impaired urinary concentrating ability in adult rats treated neonatally with enalapril.

Neonatal angiotensin-converting enzyme inhibition or angiotensin II type-1 receptor blockade induces irreversible renal histological abnormalities and an impaired urinary concentrating ability in the rat. The aim of the present study was to determine the pathophysiological mechanisms underlying the defect in urine concentration in adult rats treated neonatally with enalapril. Male Wistar rats received daily intraperitoneal injections of enalapril (10 mg kg(-1)) or saline vehicle from 3 to 24 days of age. Assessments of fluid handling and maximal urine osmolality (Uosm(max)), renal function and tubular free water reabsorption (T(c)H2O) under pentobarbital anaesthesia, renal tissue solute concentrations, renal aquaporin-2 (AQP2) expression, and kidney histology, were performed in 12-16-week-old rats. Uosm(max) (1488 +/- 109 vs. 2858 +/- 116 mosm kg(-1), P < 0.05) and maximal T(c)H2O were reduced in enalapril- vs. vehicle-treated rats after administration of 1-desamino-8-D-arginine vasopressin. Neonatally enalapril-treated rats showed marked papillary atrophy, a decrease in medullary tissue solute concentrations, and a reduction in AQP2 expression specifically in the inner medulla. Glomerular filtration rate, renal plasma flow and urinary excretion rates of sodium, potassium and chloride did not differ between groups. In conclusion, adult rats treated neonatally with enalapril showed a urinary concentrating defect of renal origin which primarily could be explained by the papillary atrophy. However, an impaired ability to generate medullary interstitial hypertonicity, and a decrease in inner medullary AQP2 expression, also seem to contribute to this defect.

Covalent photolinker-mediated immobilization of an intermediate dextran layer to polymer-coated surfaces for biosensing applications

A new method is presented for the covalent binding of dextran as an intermediate layer on surface acoustic wave (SAW) devices. For biosensing applications in aqueous media commercially available SAW devices require surface passivation to prevent corrosion of the aluminum device structures in electrolytes. Thin films of polyimide and parylene revealed exceptional passivation properties. They were used as a base for dextran immobilization. Covalent binding of dextran to polymer-coated surfaces was achieved by photoimmobilization. Aryldiazirine-functionalized bovine serum albumin served as the multifunctional light-activable linking agent (photolinker polymer). Dextran and photolinker polymer were mixed and photobonded to sensor surfaces. Essential photoimmobilization parameters were optimized. The binding of proteins to dextran applying carbodiimide chemistries was exemplified with anti-urease antibodies and the feasibility of specific immunosensing was investigated on SAW sensors connected to a fluid handling system.

Engineering Core Analysis

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Introduction Core analysis has come a long way from the days when reservoir productivity was determined by blowing through a piece of cable-tool-produced core. Our tools and methods for drilling and core analysis have changed, but our interests have not. The reservoir-rock properties that determine hydrocarbon production, the variation in these properties, and how these properties affectultimate recovery are still of primary concern. Properly engineered core analysis provides a direct measurement of these reservoir-rock properties and is an essential step in formation-evaluation, reservoir, and production engineering. Fundamental core-analysis measurements are unchanged, but advances provide the ability to test at reservoir conditions and to acquire simultaneous measurements of reservoir-dependent properties. Core analysis today uses X-ray computerized tomography (CT) to determine two- and three-dimensional (2D and3D, respectively) porosity distributions, while continuing to apply Boyle's law and Archimedes' principle to determine porosity. Mercury injection is used routinely to describe pore-throat distributions, but nuclear magnetic resonance(NMR) is becoming a popular method to delineate relationships between poreradii and permeability. This review addresses some recurrent concerns of core analysis as well as some new approaches and insights that are part of the physical reservoir model determined by core analysis. Refs. 1 through 6 provide more information on the subject. Coring and Field Operation Reservoir studies seeking to interpret and define both geological and engineering parameters dictate the core-analysis program. Core analyses mustintegrate with field and production data and eliminate reservoir uncertainties that cannot be addressed with log, well-test, or seismic data. These requirements define the coring objectives that, in turn, control coring fluid, tools, and core handling. In most cases, these objectives cannot be obtained with core retrieved in a single well. Coring is thus an integral part of the reservoir-life-cycle process, with cored wells selected to verify or provide maximum information for the current geological, engineering, or production model of the reservoir.

AN INTEGRATED PEF PILOT PLANT FOR CONTINUOUS NONTHERMAL PASTEURIZATION OF FRESH ORANGE JUICE

A pilot plant scale pulsed electric field (PEF) continuous processing system was integrated with an asepticpackaging machine to demonstrate the efficacy of PEF technology as a nonthermal pasteurization method for freshorange juice. Major system components include a 40,000 V/17 MWp high voltage pulse generator, a set of multiple stageco-field flow PEF treatment chambers, a fluid handling system for flow control and a Benco Aspack/2 aseptic thermalform packaging machine. Orange juice was processed at a 75 ~ 125 L/h flow rate and packed aseptically into 200 mLplastic cup containers. Microbially enhanced orange juice (MEOJ) tests validated the microbial inactivation effect of thisintegrated PEF system. The PEF treated and aseptically packaged fresh orange juice demonstrated the feasibility of PEFtechnology to extend the product shelf life with very little loss of flavor, vitamin C, and color.

Volume kinetics of Ringer solution during endotoxinemia in conscious rabbits

The volume effect of Ringer solution was studied in normal and endotoxinemic rabbits to find out whether endotoxin alters the body's handling of crystalloid fluid. Ten rabbits (mean body weight 4.4 kg) were given 25 ml/kg of Ringer solution over 30 min with and without receiving 20 μg/kg of endotoxin 1 h before the infusion. The hemodilution, as measured every 10 min during 2 h, was used to calculate the size of the fluid space expanded by the fluid (V) and the elimination rate constant (kr). Apart from fever and leukopenia, the injection of endotoxin reduced V from 473 (37) ml to 327 (54) ml (mean (SEM); P &lt; 0.04) and kr increased from 2.9 (0.5) ml/min to 5.9 (2.8) ml/min (not significant). Computer-based simulations using the derived kinetic data indicated that endotoxin increases the volume effect of infused fluid when it is infused very fast but reduces it when the fluid is infused more slowly.