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Power conditioning of thermoelectric generated power using dc-dc converters: A case study of a boost converter
(University of Nottingham, 1930) Twaha, Ssennoga; Zhu, Jie; Yan, Yuying
The near exhaustion of non renewable energy resources such as fossil fuels followed by disastrous climatic changes have alerted the world to invest in alternative energy sources. Thermoelectric (TE) technology is responsible for innovating TE devices such as thermoelectric generators (TEGs) which are used to generate electrical energy from heat in an environmentally friendly manner. One of the challenges behind TEG is that they have low efficiency due to low figure of merit. Moreover the power generated is unstable and therefore needs proper power conditioning mechanism before it is connected to the load. The objective of this work is to analyze the performance of a boost dc dc converter connected on TEG system. The simplified models have been used as the basis of TEG design. Results indicate that the converter is able to stabilize and boost the voltage and higher converter efficiencies are achieved at different hot side temperatures.
A microcomputer-controlled solid-state dark adaptometer
(Behavior Research Methods & Instrumentatio, 1981) Omara, Peter A.; Zwick, Harry; Van Sice, Charles W.
A low-cost microprocessor-controlled light-emitting diode (LED) dark adaptometer is described. The apparent intensities of red and green stimuli are controlled by changing the duty cycles of LED display elements which are operated at constant pulse repetition rates. The psychophysical method of limits is used to obtain threshold data. Stimulus parameters and test procedures are under software control. The design utilizes programmable integrated circuitry that may be used with a variety of microprocessors.
Neuron-based sensors for biochemical quantitation
(Proceedings of the Annual International Engineering in Medicine and Biology Society, 1989) Kisaalita, William S.; Skeen, R.S.; Van Wie, B. J.; Barnes, C. D.; Fung, S. J.; Davis, W. C.
Using intracellular recording from freshly dissected Limnea stagnalis neurons and cultured clones for mouse neuroblastoma, N-18 and N1E-115, linear relationships between several analyte concentrations and neuron electrical properties, such as action potential, are obtained. This demonstrates the suitability of neurons as primary transducers in neuron-based sensors. Initial development work that will lead to testing cultured neurons for the detection of monoclonal antibodies is reported.<>
Initiating Cross Disciplinary Research : The Neuron-Based Chemical Sensor Project
(Chemical Engineering Education, 1989) Kisaalita, William S.; Van Wie, Bernard J.; Skeen, Rodney S.; Davis, William C.; Barnes, Charles D.; Fung, Simon J.; Chun, Kukjin; Dogan, Numan S.
CHEMICAL ENGINEERING is essential to the pro-cess of bringing new areas like biotechnology, electronic, and other advanced materials to commercial success. The success of this process depends on significant cooperation between chemical engineering and other disciplines. Although there is a large volume of literature on the subject of interdisciplinary and/or crossdisciplinary research [1-3], most of it concerns large projects (as defined in Table 1) and little has been written from a chemical engineering perspective. The rationale behind the levels of funding used in Table 1 is called for. Usually in the initial stages of a project, $30,000 to $70,000 for a single year is only sufficient to generate pilot data and perhaps to provide incentive for the formation of a cross-or an interdisciplinary team. A yearly budget of $70,000 to $150,000 for a period of three to five years provides enough for more than one graduate student to focus on specific aspects relating to the expertise of each co-investigator. Amounts above $150,000 can support large groups with more personnel per discipline involved as well as supporting inter-university research activities where extensive travel may be necessary. The purpose of this paper is to address the problems
Evaluation of Neuron-Based Sensing with the Neurotransmitter Serotonin
(Biosensors and Bioelectronics, 1990) Skeen, Rodney S.; Kisaalita, William S.; Van Wie, Bernard J.; Fung, Simon J.; Barnes, Charles D.
Results are presented on the development of a novel biosensor which will use neurons or neuronal components as both the recognition elements and primary transducers for analyte quantitation. This concept is demonstrated and evaluated by exposing identified neurons from the visceral ganglia of the pond snail Limnea stagnalis to the model analyte serotonin. Experiments reveal a reversible, concentration-dependent increase in the rate of spontaneous action potential generation, over a concentration range of four orders of magnitude. Studies with the antagonist methysergide verify that this response is mediated through serotonin-sensitive receptors. Exposure of the neurons to serotonin causes the firing frequency to rapidly increase to a maximum and then slowly diminish to a sub-optimal level. It was found that the maximum frequency provides an indication of chemical concentration that is repeatable. Data are also presented which further advanced the field of neuronal biosensing by demonstrating both the effects of cell to cell variability on response reproducibility and the effects of the desensitizing response on the operation of a neuron-based sensor in both a continuous and discontinuous mode.
Optimization of Glass Microelectrode Properties by Response Surface Methodology
(Journal of neuroscience methods, 1991) Kisaalita, William S.; Skeen, Rodney S.; Van Wie, Bernard J.; Barnes, Charles D.; Fung, Simon J.
Glass microelectrodes filled with electrolyte solutions are standard tools for electrophysiological studies. However, for any given application, there are limitations to the properties of the microelectrode, such as impedance and shank length, that can yield satisfactory results. The trial and error approach in pulling electrodes with the desired properties can be time consuming. The use of a response surface procedure which allows the experimenter to change more than one factor at a time and therefore determine the desired puller condition more efficiently is demonstrated. Also, design improvements for the World Precision Instrument, Model PUL-1, Microelectrode puller, used in this study are suggested.
Biosensor Standards Requirements
(Biosensors & Bioelectronics, 1992) Kisaalita, William S.
Since biosensor applications are springing up in many places, it should be the wish of all biosensor manufacturers, their customers, as well as those in academia, that the same language and requirements are used to describe similar products. In order to find answers to the question as to whether the time is right to consider developing standards for biosensors, and if so, what the priority areas might be, we have conducted a survey of biosensor users and/or manufacturers. It is the purpose of this article to report our survey results.
A Fiber-optic System for Measuring Single Excitation-Dual Emission Fluorescence Ratios in Real Time
(Biotechnology progress, 1992) McCarthy, John F.; Magin, Richard L.; Kisaalita, William S.; Slininger, Patricia J.
The development and subsequent evaluation of a fiber‐optic system for measuring single excitation—dual emission fluorescence ratios in real time is described. The design of the flashlamp excitation source, optics, electronics, and computer software is discussed. The dual emission pH sensitive fluorophore 1, 4‐dihydroxyphthalonitrile (1, 4‐DHPN) was used to test the performance of this system. The flexible design of this modular system permits the use of other single excitation—dual emission fluorophores by simply changing the appropriate optical filters. Upon a single 340–380‐nm excitation, pH‐sensitive emissions were monitored at 488 nm and 434 nm. The ratio of these emissions (488/434) was then computed in real time, for a 2 mM solution of 1, 4‐DHPN, while the pH was titrated over the range 5–9. The nonlinear, system‐dependent, calibration curve of pH versus the ratio of emission wavelengths was empirical fit by a fourth‐order polynomial (r2 = 0.995). Reliable pH measurements in the range 6–8 were obtained using concentrations of 1, 4‐DHPN as low as 50 μM. The standard deviation of pH measurements using a 1 mM solution of 1, 4‐DHPN, near neutral pH, was found to be approximately 0.1 pH unit
Defined media for optimal pyoverdine production by Pseudomonas fluorescens 2-79
(Applied microbiology and biotechnology, 1993) Kisaalita, William S.; Slininger, Patricia J.; Bothast, Rodney J.
Pseudomonas fluorescens strain 2-79 (NRRL-15132) produces a fluorescent yellow-green pyoverdine when cultured on Fe(III)-poor medium. When cultured on Fe(III)-rich medium, strain 2-79 produces an antibiotic, phenazine 1-carboxylic acid, which is effective in suppressing plant fungal diseases such as take-all of wheat. A 23 factorial design was used to examine pyoverdine production as a function of the presence or absence of Bacto casamino acids, purines-pyrimidines and vitamins in an iron-deficient medium. Amino acids were found to be an important factor (P=0.0002). A Plackett-Burman design was used to identity eight amino acids, out of the 19 present in casamino acids, that were responsible for the increased pyoverdine production: methionine, valine, isoleucine, tyrosine, proline, phenylalanine, glutamic acid, and glycine. Biomass was enhanced only by glutamic acid.
Effect of Pseudomonas fluorescens (2–79) culture age on the relationship between optical density and biomass
(Biotechnology techniques, 1994) Kisaalita, William S.
The effect of cell-cell adhesion (clump formation) on the relationship between optical density and dry biomass was investigated for Pseudomonas fluorescens (2–79). Calibration curves were generated at the beginning, middle and end of the arithmetic growth phase, as well as during the decay phase. The results show that use of a single biomass-turbidimetric equation for the entire arithmetic growth phase may yield erroneous results.
Purification of Pyoverdines of Pseudomonas fluorescens 2-79 by Copper-Chelate Chromatography
(Applied and environmental microbiology, 1995) Xiao, Rong; Kisaalita, William S.
Three pyoverdines, Pf-A, Pf-B, and Pf-C, were purified with copper-chelate Sepharose and Sephadex G-15 columns from Pseudomonas fluorescens 2-79, and the yields (per 100 ml of culture supernatant) were 2.8, 21.6, and 3.2 mg, respectively. The absorption and fluorescence spectra of these pyoverdines were strongly pH dependent. Characteristic changes in the maximal absorbance wavelengths were observed when Fe(sup3+) or Cu(sup2+) was added. The addition of Cu(sup2+) shifted the pyoverdine Pf-B absorbance spectrum so that it exhibited a single peak at 410 nm but did not give rise to a new absorbance maximum at approximately 460 nm, which appeared when Fe(sup3+) was added. Fluorescence quenching experiments revealed that the forward reaction rate constant with pyoverdines was much higher with Cu(sup2+) (10(sup4) to 10(sup5) M(sup-1) s(sup-1)) than with Fe(sup3+) (10(sup2) M(sup-1) s(sup-1)). However, Cu(sup2+)-pyoverdine complexes were completely dissociated by EDTA at a low concentration (0.1 mM), while the level of Fe(sup3+)-pyoverdine complex dissociation at the same EDTA concentration was relatively low. The dissociation of Fe(sup3+)-pyoverdine complexes was EDTA concentration dependent. Formation of free pyoverdine was observed when the three types of Fe(sup3+)-pyoverdine complexes were incubated separately with P. fluorescens 2-79 cells, thus demonstrating that pyoverdines Pf-A, Pf-B, and Pf-C mediate iron transport.
Assessment of Murine Neuroblastoma (N1E-115) Resting Membrane Potential by Confocal Microscopy
(Journal of Fluorescence, 1996) Hernandez, Miguel; Kisaalita, William S.; Farmer, Mark A.
Digital imaging (confocal microscopy) and a slow potentiometric dye (tetramethylrhodamine methyl ester) were used to assess the resting membrane potential (V m) of murine neuroblastoma cells (N1E-115). The averageV m was found to be −64.0±2.0 mV. The difference between this and the previously reported higher values was attributed to the use of glass microelectrode techniques that probably caused mechanical injury to the cell membranes: Digital imaging of N1E-115V m was found to be sensitive, reproducible, fast, and simple.
GABAA receptor currents recorded from Müller glial cells of the baboon (Papio cynocephalus) retina
(Neuroscience letters, 1996) Reichelt, Winfried; Hernandez, Miguel; Damian, Raymond T.; Kisaalita, William S.
The effect of γ-aminobutyric acid (GABA) application on acutely isolated, non-cultivated Muller glial cells from the baboon retina was studied using the whole-cell voltage-clamp technique. Application of GABA (0.1 mM) generated inward currents at a holding potential of −80 mV as well as an increase in current noise. The GABA-activated current had a reversal potential of 18.6 mV and was therefore supposed to be a. Cl− current (ECl = 5 mV). The GABAA receptor agonist muscimol (0.1 mM) elicited an inward current and bicucullin (0.5 mM), a blacker of the GABAA receptor, diminished the GABA responses in our experiments completely. Baclofen (0.1 mM), a GABAB agonist, neither had an effect when applied under conditions where the dominant Müller cell K+ currents were unblocked, nor when the K+ currents were blocked by application of Ba2+ (1 rnM). Glycine (0.1 mM) was ineffective as well. From these results we conclude that the baboon retinal Muller cells possess GABAA receptors. However, these have recently been discovered on skate Müller cells whereas GABAA receptors could not be found on Muller cells of guinea pig, pig, mouse, rat and rabbit.
Comparative evaluation of the susceptibility of neuronal (N1E-115) and non-neuronal (HeLa) cells to acetylsalicylic acid (ASA) cytotoxicity by confocal microscopy
(Toxicology in vitro, 1996) Hernandez, M.; Kisaalita, William S.
A voltage-sensitive probe, tetramethylrhodamine methyl ester (TMRM) and digital imaging (confocal microscopy) were used to quantify differential membrane potential alteration in neuronal (murine neuroblastoma, N1E-115) and non-neuronal (human epithelial-like, HeLa) cells, after 1 and 24 hr of exposure to a knownin vivo neurotoxic agent, acetylsalicylic acid (ASA), as a first step in substantiating the relevance of alteration in resting membrane potential (Vm) as a neurotoxic endpoint. After 1 hr of exposure, ASA (5.0 mm) hyperpolarized both HeLa and N1E-115 cells. Vm decreased from −57.6mV± 2.8 (n= 20cells)to−74.7mV± 1.9 (n= 20cells) and from −64.0mV± 2.1 (n= 20cells)to−82.5mV± 3.4 (n= 20cells) for HeLa and N1E-115 cells, respectively. The extent of hyperpolarization was found to be ASA concentration dependent. There was no significant difference (P < 0.05) between the cell lines with respect to ASA sensitivity, suggesting that under these experimental conditions, ASA exhibited no selective cytotoxic activity for the neuronal cells. In comparison with control cultures, 24-hr ASA (5.0 mm) exposure did not affect the surviving cell Vm. The results of the present study were inconclusive with respect to the suitability of Vm alteration as an indicator of neurotoxic potential.
Development of resting membrane potentials in differentiating murine neuroblastoma cells (N1E-115) evaluated by flow cytometry
(Cytotechnology, 1997) Kisaalita, William S.; Bowen, John M.
With the aid of a voltage-sensitive oxonol dye, flow cytometry was used to measure relative changes in resting membrane potential (Vm) and forward angle light scatter (FALS) profiles of a differentiating/differentiated murine neuroblastoma cell line (N1E-115). Electrophysiological differentiation was characterized by Vm establishment. The (Vm)-time profile was found to be seed cell concentration-dependent for cell densities of less than 2 × 104 cells/cm2. At higher initial cell densities, under differentiating culture conditions, Vm development commenced on day 2 and reached a steady-state on day 12. The relative distribution of differentiated cells between low and high FALS has been proposed as a potential culture electrophysiological differentiation state index. These experiments offer a general methodology to characterize cultured excitable cells of nervous system origin, with respect to electrophysiological differentiation. This information is valuable in studies employing neuroblastoma cells as in vitro screening models for safety/hazard evaluation and/or risk assessment of therapeutical and industrial chemicals under development.
Effect of Medium Serum Concentration on N1E-115 Neuroblastoma Membrane Potential Development
(Animal, 1997) Kisaalita, William S.; Bowen, John M.
Propidium iodide (PI) emissions were determined by PMT2 after pas-sage through a 610-nm long-pass filter. SSC was determined by PMT4. FALS signals were linearly amplified with a gain of 2. Unless otherwise stated, 50,000 events were counted at an approximate rate of 200 events per second. Because subcellular debris has low FALS, this parameter was used to gate out these particles. Oxonol fluorescence analysis was restricted to events that were PI-negative, since dead or dying cells are stained by PI. To compare results for experiments conducted at different times, polystyrene fluorospheres (Coul-ter Corporation, Hialeah, FL) were used to set the PMT,(oxonol signal) and PMT4 (SSC signal) at channel numbers of 35? 1 and 100? 2, respectively, before each experiment. DMSO was included in this study as a positive control, because it is considered one of the most potent enhancers of electrical excit-ability among other chemical differentiating agents (Spector and Baumgold, 1982). Aminopterin was also included as a positive con-trol. Aminopterin blocks the normal biosynthetic pathway by which nucleotides are made (Henderson et al., 1965) and therefore was expected to kill off most if not all the dividing (nondifferentiating) cells and thus yield the most differentiated cells. Previous Vm results obtained by intracellular and patch clamp recording techniques on a few cells have indicated that the transition from low to high Vm occurred between 7 and 10 days (Kimhi et al., 1976; Santone et al., 1986; Baumgold and Spector, 1987; Cosgrove and Cobbett, 1991).
Iron acquisition from transferrin and Iactoferrin by Pseudornonas aeruginosa pyoverdin
(Microbiology, 1997) Xiao, Rong; Kisaalita, William S.
Pseudomonas aeruginosa is an opportunistic pathogen which is frequently found in clinical specimens from burns, surface wounds, urinary tract, ear and eye infections, and is commonly isolated from the lungs of patients with cystic fibrosis (CF)(Doggett et al., 1966; Reynolds et al., 1976). In response to iron deprivation P. aeruginosa produces two unrelated siderophores, pyoverdin and pyochelin, as well as membrane receptors for binding the corresponding iron-siderophore complexes. Both of these siderophores promoted the growth of P. aeruginosa when added to medium with iron-transferrin or human sera as the iron sources (Ankenbauer et al., 1985). Because of the higher iron-pyoverdin binding constant (lo3,)(Demange et al., 1990), in comparison to that of iron-pyochelin (lo5)(Cox & Graham, 1979), pyoverdin was considered to be more effective. It has been reported that a pyochelin-deficient mutant (Pvd+ Pch-) strain grew as well as the parent strain whereas a pyoverdin-deficient mutant (Pvd-Pch+) exhi-Abbreviations: CF, cystic fibrosis; ICP, inductively coupled plasma. bited severely retarded growth (Ankenbauer et al., 1985).
Size Changes in Differentiating Neuroblastoma Cells
(In vitro cellular & developmental biology. Animal, 1997) Kisaalita, William S.; Lund, Robert B.; Evans, Mark
Day 12 0.0001 0.5572 0.4714 0.0001 0.0005 0.0001 0.0081 0.0001 control reject don't don't reject reject reject reject reject Ho rej. Ho rej. Ho Ho Ho Ho Ho Ho aBlocks below and above the main diagonal compare control vs. control and treatment vs. treatment, respectively, across the day of study. bp-values for Z-test. light scatter (FALS), one of the flow cytometry parameters, is as light of the same wavelength as the illuminating laser bea is refracted as it passes through the cell so as to diverge fr original path of the laser beam by approximately 0.5'. Henc is dependent on both cell refractive index and size. The r distribution of differentiating/differentiated cells between lo high-FALS has been proposed as a potential culture electrop logical differentiation index before and after terminal differe (Kisaalita and Bowen, 1997). Our purpose here is to study t lationship between cell-size distribution and culture age for entiating and control cells, and perhaps more importantly, ass effect of cell differentiation size changes to FALS. How c changes influence FALS has biological relevance when usin as a measure of the extent of electrophysiological differentiat saalita and Bowen, 1997). N1E-115 cells of Passage 12 were obtained from Dr. M. Nire National Institutes of Health (Bethesda, MD). Previously pub protocols for N1E-115 cell cultures (Kimhi et al., 1976; Mo and Spector, 1978; Miyake and Kurihara, 1983) were fol Briefly, N1E-115 cells were routinely cultured in 370 C air p CO2 at 90% relative humidity. The growth media was comp Dulbecco's modified Eagle's medium (DMEM) containing NaHCO3 (wt/vol) and supplemented with 13% fetal bovine (FBS), 50 units/ml penicillin, 50 g/ml streptomycin, and 2 m tamine. Cultures were monodispersed gently by flushing the c ent cells from the base of a 75-cm2 T-flask (Costar, Cambrid by a stream of medium ejected from a Pasteur pipette. The sions were centrifuged (500 g, 10 min) and the pellet resusp in 25-cm2 T-flasks (Costar) with fresh growth media at 2.0 viable cells (able to exclude trypan blue) per flask, unless oth stated. Flasks (in triplicate) were incubated for 24 h to allow to settle and adhere to the base of the flask. Cells were then e to the differentiating medium (this is the same as the growth except serum was reduced to 0.5%). The differentiating medi changed every 3 to 4 d. Cell-size data were taken at Days 1, 6, 8, 10, and 12 after exposure to the differentiating mediu saalita and Bowen (1997) have previously shown that it tak
Fluorescent Pseudomonad Pyoverdines Bind and Oxidize Ferrous Ion
(Applied and Environmental Microbiology, 1998) Xiao, Rong; Kisaalita, William S.
Major pyoverdines from Pseudomonas fluorescens 2-79 (Pf-B), P. aeruginosa ATCC 15692 (Pa-C), and P. putida ATCC 12633 (Pp-C) were examined by absorption and fluorescence spectroscopic techniques to investigate the interaction between ferrous ion and the pyoverdine ligand. At physiological pH, ferrous ion quenched the fluorescence of all three pyoverdines much faster than ferric ion did. Also, increased absorbance at 460 nm was observed to be much faster for Fe2+-pyoverdine than for Fe3+-pyoverdine. At pH 7.4, about 90% of Fe3+was bound by pyoverdine Pa-C after 24 h whereas Fe2+was bound by the pyoverdine completely in only 5 min. The possibility that Fe2+ underwent rapid autoxidation before being bound by pyoverdine was considered unlikely, since the Fe2+concentration in pyoverdine-free samples remained constant over a 3-min period at pH 7.4. Incubating excess Fe2+ with pyoverdine in the presence of 8-hydroxyquinoline, an Fe3+-specific chelating agent, resulted in the formation of a Fe3+-hydroxyquinoline complex, suggesting that the iron in the Fe2+-pyoverdine complex existed in the oxidized form. These results strongly suggested that pyoverdines bind and oxidize the ferrous ion.
Micro-Perfusion Flow Cell for Imaging Cultured Cells
(Biotechniques, 1999) Agnihotri, Naveen; Kisaalita, William S.; Keith, Charles H.
We present a unique design for a flow cell with a small working volume that allows rapid displacement of media viewed under high power and short working distance objectives. The flow cell has a small internal depth (ca. 0.033 cm) and volume (ca. 0.05 mL) and is easy to handle. Made of Delrin®, the flow cell is biologically inert. We have used the flow cell for fluorescence imaging of PC12 cells loaded with tetramethylrhodamine dextran (TMRD) and other dyes.

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