Fluid Handling Research Articles

Metal‐polymer nanocomposites for integrated microfluidic separations and surface enhanced Raman spectroscopic detection

The widespread development of microfluidics (microfluidics) has allowed the extension of efficient separations, fluid handling, and hyphenation with many detection modes to a small, portable, highly controllable physico-chemical platform. Surface enhanced Raman spectroscopy (SERS) offers the powerful advantage of obtaining vibrational spectroscopic information about analytes in an aqueous matrix with negligible background. The mating of electrophoretic separations with vibrational spectroscopy on a microfluidic device will allow the chromatographic efficiency of capillary electrophoresis (CE) with the unequivocal analyte "fingerprinting" capability of detailed structural information. By utilizing SERS as a means of detection, this work promises to yield redress for the hindrances of electrophoretic separations, including uncertainty in analyte band identification due to changing migration times as well as compromised detection sensitivity for non-fluorescent analytes. Our work represents the first steps toward developing CE-SERS on a microfluidic platform with a region of novel metal-pliable polymer nanocomposite SERS substrate fabricated directly into the device. The device fabrication material has been extensively employed by the microfluidics community for over five years. SERS detection can be achieved in real time or after the separations, with on-column laser-induced fluorescence employed as a secondary detection mode used for confirmation of efficiencies and band locations.

Considerations for a canned motor pump

There are three basic types of sealless pump technology available today: Magnetic Drive, Canned Motor and Hybrids. While a cost benefit analysis for each of the three categories can be made based on the requirements of a facility, Calum Scott C.Eng M I Mech E, product specialist at Hayward Tyler Fluid Handling, argues that a canned motor pump (CMP) can offer the highest degree of containment (double containment), reduced maintenance cost and improved reliability when properly applied.

360 NFkB expression and disease outcome in prostate cancer

The miniaturization of biological and chemical analytical devices by micro-electro-mechanical-systems (MEMS) technology has posed a vital influence on such fields as medical diagnostics, microbial detection and other bio-analysis. Among many miniaturized analytical devices, the polymerase chain reaction (PCR) microchip/microdevices are studied extensively, and thus great progress has been made on aspects of on-chip micromachining (fabrication, bonding and sealing), choice of substrate materials, surface chemistry and architecture of reaction vessel, handling of necessary sample fluid, controlling of three or two-step temperature thermocycling, detection of amplified nucleic acid products, integration with other analytical functional units such as sample preparation, capillary electrophoresis (CE), DNA microarray hybridization, etc. However, little has been done on the review of above-mentioned facets of the PCR microchips/microdevices including the two formats of flow-through and stationary chamber in spite of several earlier reviews [Zorbas, H. Miniature continuous-flow polymerase chain reaction: a breakthrough? Angew Chem Int Ed 1999; 38 (8):1055–1058; Krishnan, M., Namasivayam, V., Lin, R., Pal, R., Burns, M.A. Microfabricated reaction and separation systems. Curr Opin Biotechnol 2001; 12:92–98; Schneegaβ, I., Köhler, J.M. Flow-through polymerase chain reactions in chip themocyclers. Rev Mol Biotechnol 2001; 82:101–121; deMello, A.J. DNA amplification: does ‘small’ really mean ‘efficient’? Lab Chip 2001; 1: 24N–29N; Mariella, Jr. R. MEMS for bio-assays. Biomed Microdevices 2002; 4 (2):77–87; deMello AJ. Microfluidics: DNA amplification moves on. Nature 2003; 422:28–29; Kricka, L.J., Wilding, P. Microchip PCR. Anal BioAnal Chem 2003; 377:820–825]. In this review, we survey the advances of the above aspects among the PCR microfluidic devices in detail. Finally, we also illuminate the potential and practical applications of PCR microfluidics to some fields such as microbial detection and disease diagnosis, based on the DNA/RNA templates used in PCR microfluidics. It is noted, especially, that this review is to help a novice in the field of on-chip PCR amplification to more easily find the original papers, because this review covers almost all of the papers related to on-chip PCR microfluidics.

Focus on the well-primed US pump industry

For this month's special focus, World Pumps returns to the USA's $6 billion/year pump market. According to a recent study from Freedonia, demand for products from the country's 300-plus pump manufacturers is currently rising 5% per year on average as most pump-using industries emerge from the recession of the early 2000s, and this growth is likely to continue until at least 2007. By way of introduction, John Michael Paz , president of Godwin Pumps of America, considers the development of markets for automatic self-priming pumps in the USA. Then, Steve Schmitz of ITT's Fluid Handling Division reviews the problem of noise in pumps used in cooling tower applications, its causes and control. Finally, returning to the theme of self-priming pumps, John Kanute of Goulds Pumps takes us back to basics with a discussion of their principles of operation, advantages and use.

Automated electrochemical CV profiling of LED structures on wafer scale

A newly developed equipment is presented to perform (photo-)electrochemical (PEC) CV profiling in semiconductor structures. The equipment is fully automated to handle sample sizes from some mm2 up to 6″ wafers. Fully automated loading of the electrochemical cell, fluid handling system, automatic unloading of the fluid, and drying of the sample at the end of the measurement are incorporated into the setup. Furthermore, together with a wafer stepper it is possible to perform wafer topography measurements. The hardware makes use of a recently, especially for group III-nitrides developed etch procedure named “cyclic oxidation”: featuring high etch rates in the range of 3 μm/h for n- and p-type (Al,In)GaN layers together with mirror-like etched surface morphology. Using this new equipment, LED structures have been characterized by CV profiling. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Reducing pump noise in cooling tower applications

Cooling tower applications are one of the areas where excessively noisy pumps are most frequently encountered. High noise levels are not only a nuisance but also a potential indicator of diminished pump performance.Steve Schmitz, senior product line manager for centrifugal pumps at ITT's Fluid Handling Division, provides practical tips for identifying the causes of excessive noise and for reducing or eliminating it, thereby improving operating costs.

Design and Optimization of Compact Microscale Electrophoretic Separation Systems

The ability to manipulate and synthesize chemical species on microchip devices provides access to a new and exciting field. These technologies have several advantages throughout the industrial and scientific communities, especially in the emerging areas of biomedical engineering and the life sciences. Recent advances in microscale mixing, reaction, separation, and fluid handling have opened new areas in which process systems engineering techniques can be applied. Here we discuss our initial efforts at creating automatic synthesis methods for the design of microchip-based electrophoretic separation systems that occupy minimal areas. We use piecewise algebraic and logic models to compare the conflicting design goals of maximum system performance and minimum device area. We have implemented both heuristic and numerical optimization design techniques. The long-term goal of our work is the development of methodologies for the design of complete lab-on-a-chip devices.

Pediatric neurotransmitter diseases.

The pediatric neurotransmitter disorders represent a challenging group of rare neurometabolic disorders classified on the basis of alterations in neurotransmitter metabolic pathways. The disorders are currently classified into disturbances of monoamine and gamma-aminobutyric acid (GABA) metabolism, although disorders of other neurotransmitters, such as glutamate and melatonin, may well be recognized in future investigations. This review summarizes the clinical and laboratory features of selected pediatric neurotransmitter disorders that have been partially delineated. Of the monoamine group, these are Segawa disease or guanosine triphosphate-cyclohydrolase I deficiency, aromatic L-amino acid decarboxylase deficiency, and tyrosine hydroxylase deficiency. Of the GABA disorders, these are pyridoxine-dependent epilepsy, GABA transaminase deficiency, and succinic semialdehyde dehydrogenase deficiency. As proper collection, handling, and interpretation of cerebrospinal fluid is required for assessment of most of these disorders, we end by summarizing important considerations for obtaining cerebrospinal fluid samples.

‘Sensing’ significant savings with VFD systems

Although a great deal of effort often goes into the hardware specification for variable frequency drives (VFD), little attention or understanding is applied to how to control the system. The belief is that the hardware of the VFD itself causes the energy savings. The core of the misunderstanding appears to be the term ‘Centrifugal Affinity Laws / Pump Laws’. In this article John Everhart of ITT Industries — Fluid Handling Division takes a look at these ‘Laws’, the assumptions behind them and the savings that can be realistically expected in most systems.

Focus on Laboratory Equipment

Focus on Laboratory Equipment

Colfax withdraws from Netzsch buyout

Colfax Corp, the US-based producer of fluid handling and power transmission products, has withdrawn from its planned takeover of Germany’s Netzsch Group. Privately-held Colfax, with headquarters in Richmond, Virginia, said that it could not meet the parameters of the acquisition finance facility. Visit www.filtsep.com for the latest filtration industry news

Solving the "world-to-chip" interface problem with a microfluidic matrix.

We report an effective solution to the macroscopic/microfluidic interface issue and demonstrate how microfluidics can achieve impressive economies of scale in reducing the complexity of pipetting operations. Using an N x N microfluidic matrix with N = 20, we performed N2 = 400 distinct PCR reactions with only 2N + 1 = 41 pipetting steps, compared with the 3N2 = 1200 steps required with conventional fluid handling. Each vertex of the matrix has a 3-nL reactor, and a single 2-microL aliquot of polymerase is amortized over all 400 independent reactions, thus dramatically reducing sample overhead and minimizing reagent consumption. Beyond PCR, the matrix chip provides a general method to perform chemical and biological experiments with precious reagents in a highly automated fashion.

Prominent focuses on complete solutions

ProMinent Dosiertechnik GmbH has been reorganized into two business segments: Chemical Fluid Handling (CFH) and Water Treatment Systems (WTS), in a shift away from being a pure component manufacturer to become a complete solutions partner. This is a short news story only. Visit www.worldpumps.com for the latest pump industry news.

A model for visualizing fluid handling by the gastrointestinal tract.

Students often find models useful in learning or reviewing physiological concepts. As a result, we have developed a physical model of the gastrointestinal tract, which is used in the GI sections of our medical and graduate physiology courses to demonstrate ingested, secreted, reabsorbed, and

Renal fluid and electrolyte handling in BKCa-beta1-/- mice.

Large-conductance Ca(2+)-activated K(+) channels (BK(Ca)) are composed of pore-forming alpha-subunits and one of four accessory beta-subunits. The beta1-subunit, found predominantly in smooth muscle, modulates the Ca(2+) sensitivity and pharmacological properties of BK(Ca). BK(Ca)-beta1 null mice (Mbeta1(-/-)) are moderately hypertensive, consistent with the role of BK(Ca) in modulating intrinsic vascular tone. Because BK(Ca) are present in various renal cells including the mesangium and cortical collecting ducts, we determined whether fluid or electrolyte excretion was impaired in Mbeta1(-/-) under euvolemic, volume-expanded, or high-salt diet conditions. Under euvolemic conditions, no differences in renal function were found between Mbeta1(-/-) and Mbeta1(+/+). However, glomerular filtration rate (GFR) and fractional K(+) excretion were significantly impaired in Mbeta1(-/-) in response to acute volume expansion. In contrast, Mbeta1(-/-) exhibited enhanced Na(+) excretion and fractional Na(+) excretion responses to acute volume expansion. Differences in renal function between Mbeta1(+/+) and Mbeta1(-/-) were not observed when chronically treated with a high-salt diet. These observations indicate that the beta1-subunit of BK(Ca) contributes to the increased GFR that accompanies an acute salt and volume load and raises the possibility that it is also involved in regulating K(+) excretion under these conditions.

AxFlow expands in Spain with Colfax Bombas buy

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.

INJECTION MIXING SYSTEM FOR BOOMLESS, TARGET–ACTIVATED HERBICIDE SPRAYING

An injection mixing system for herbicide solution was developed for a target–activated spray system designed for roadside weed control. Commercial components were used for fluid handling, and two interface techniques were developed for communication between the target sensing sprayer and the injection system. An electronic technique used digital scaling of the relative weed load to characterize and initiate changes in relative injection rate of active ingredient. The alternative mechanical technique relied on fluid coupling between the spray emission and the injection systems to maintain the desired concentration of active ingredient in the spray mix. Performance of the injection system was evaluated using salt tracer as the injection solution and in–line liquid conductivity measurements to determine concentration. Response, stability, and steady–state accuracy of the system were quantified over a 12:1 turndown ratio at command rates of 0.5 to 10 Hz. Both interface techniques maintained desired tracer concentration within 10% of the target level when subjected to highly variable weed loads. The electronic technique provided faster response and the possibility for feedforward control. Liquid pressure at the nozzle manifold was maintained during the rapid changes in spray emission by using 3–way valves to shuttle flow between the spray nozzle and a bypass line. Nozzle pressure remained within 10% of the desired value during the dynamic testing. The fluid handling and injection control systems were transparent to the operator and required no changes to the operator interface typically used for conventional spraying.

Effects of Helichrysum ceres Extracts on Renal

Objective. To evaluate the effects of Helicrysum ceres root and leaf extracts on mean arterial blood pressure and renal fluid and electrolyte handling in anesthetized male Sprague-Dawley rats. Design. Cross sectional study. Setting. Departments of Physiology and Pharmacy, University of Zimbabwe. Subjects. Eight separate groups comprising of control and treated Male Sprague–Dawley rats (n = 6 in each group) were anesthetized and placed on a continuous jugular infusion of 0.077 M NaCl at 150 µL min−1. The left carotid artery was cannulated with polythene tubing and then connected to a pressure transducer for blood pressure measurements. After 3 h equilibration period, consecutive 20 min urine collections and blood pressure measurements were made over the subsequent 4 h of 1 h 20 min control, 1 h treatment and 1 h 40 min post-equilibration periods for measurements of urine flow and Na+ and K+ excretion rates. Helichrysum ceres leaf extracts at 0.3, 0.6 and 1.2 µg min−1or roots 0.3, 3 and 6 µg min−1 were added to the infusate during the treatment period. To establish whether the extracts had activities comparable to drugs already in use, a separate group of animals was administered furosemide (0.12 µg min−1) during the treatment period. Main Outcome Measures. Hypotension, Natriuresis and Diuresis. Results. Infusion of graded doses of aqueous leaf extracts of Helicrysum ceres provoked an increase in urine flow rates but did not achieve statistical significance. However, the extracts produced dose dependent decreases in potassium excretion as well as increases in urinary Na+ outputs and diuresis. Administration of the various doses of aqueous root extracts of Helicrysum ceres significantly increased urine flow rate and urinary Na+ excretion in all groups. The intravenous (i.v.) administration of the aqueous root or leaf extracts of Helichrysum ceres significantly depressed mean arterial blood pressure (MAP). The diuretic and natriuretic effects of plant extracts were not significantly different to that of furosemide. Conclusion. The results suggest that oral administration to rats of aqueous crude Helicrysum ceres root or leaves extracts induce hypotension and natriuresis.

IonWorks™ HT: A New High-Throughput Electrophysiology Measurement Platform

To address the throughput restrictions of classical patch clamp electrophysiology, Essen Instruments has developed a plate-based electrophysiology measurement platform. The instrument is an integrated platform that consists of computer-controlled fluid handling, recording electronics, and processing tools capable of voltage clamp whole-cell recordings from thousands of individual cells per day. To establish a recording, the system uses a planar, multiwell substrate (a PatchPlate). The system effectively positions 1 cell into a hole separating 2 fluid compartments in each well of the substrate. Voltage control and current recordings from the cell membrane are made subsequent to gaining access to the cell interior by applying a permeabilizing agent to the intracellular side. Based on the multiwell design of the PatchPlate, voltage clamp recordings of up to 384 individual cells can be made in minutes and are comparable to measurements made using traditional electrophysiology techniques. An integrated pipetting system allows for up to 2 additions of modulation agents. Typical throughput, measurement fidelity, stability, and comparative pharmacology of a recombinant voltage-dependent sodium channel (hNav1.3) and a voltage-gated potassium channel (hKv1.5) exogenously expressed in CHO cells are presented. The IonWorks HT device can be used in biophysical and pharmacological profiling of ion channels in an environment compatible with high-capacity screening.

Endothelin inhibits NPR-A and stimulates eNOS gene expression in rat IMCD cells.

We have shown in previous studies that high extracellular tonicity is associated with increased expression of the type A natriuretic peptide receptor (NPR-A) and reduced expression of the endothelial NO synthase (eNOS) gene in cultured rat inner-medullary collecting duct cells. The vasoactive peptide endothelin has been shown to be avidly expressed in this nephron segment, and to be subject to osmotic regulation. We asked whether endothelin might play a role in the control of basal or osmotically regulated NPR-A or eNOS gene expression in these cells. Although exogenous endothelin had little or no effect on basal expression of eNOS mRNA or protein or NPR-A gene expression, both the type A (BQ610) and type B (IRL1038) endothelin receptor antagonists proved capable of reducing eNOS mRNA and protein expression, and increasing levels of the NPR-A mRNA. Increased extracellular tonicity reduced endothelin mRNA accumulation in these cells (approximately 15% of control levels); however, exogenous endothelin failed to normalize osmotically increased NPR-A activity or expression, or osmotically suppressed eNOS expression. Collectively, these data demonstrate the presence of a number of independent but highly interactive local regulatory networks governing fluid and electrolyte handling in this distal nephron segment.