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- Title
- A NOVEL SETUP FOR HIGH-PRESSURE RAMAN SPECTROSCOPY UNDER A MICROSCOPE.
- Creator
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Oakeson, Thomas, Schulte, Alfons, University of Central Florida
- Abstract / Description
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Functional properties of biological molecules and cells are affected by environmental parameters such as temperature and pressure. While Raman spectroscopy provides an intrinsic probe of molecular structural changes, the incorporation of a microscope enables studies of minuscule amounts of biological compounds with spatial resolution on a micron scale. We have developed a novel setup which combines a Raman microscope and a high pressure cell. A micro-capillary made out of fused silica...
Show moreFunctional properties of biological molecules and cells are affected by environmental parameters such as temperature and pressure. While Raman spectroscopy provides an intrinsic probe of molecular structural changes, the incorporation of a microscope enables studies of minuscule amounts of biological compounds with spatial resolution on a micron scale. We have developed a novel setup which combines a Raman microscope and a high pressure cell. A micro-capillary made out of fused silica simultaneously serves as the supporting body and the optical window of the pressure cell. The cell has been tested over the pressure range from 0.1 to 4 kbar. Raman spectra of less than 100 nanoliter amount of amino acid and protein solutions have been measured in the micro-capillary high pressure cell. It is also demonstrated that the setup is well suited for spectrally resolved fluorescence measurements at variable pressure.
Show less - Date Issued
- 2007
- Identifier
- CFE0001683, ucf:47208
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001683
- Title
- INSULATOR-INSULATOR CONTACT CHARGING AS A FUNCTION OF PRESSURE.
- Creator
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Hogue, Michael, Mucciolo, Eduardo, University of Central Florida
- Abstract / Description
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Metal – metal and to an extent metal – insulator contact or triboelectric charging are well known phenomena with good theoretical understanding of the charge exchange mechanism. However, insulator – insulator charging is not as well understood. Theoretical and experimental research has been performed that shows that the surface charge on an insulator after triboelectric charging with another insulator is rapidly dissipated with lowered atmospheric pressure. This pressure...
Show moreMetal – metal and to an extent metal – insulator contact or triboelectric charging are well known phenomena with good theoretical understanding of the charge exchange mechanism. However, insulator – insulator charging is not as well understood. Theoretical and experimental research has been performed that shows that the surface charge on an insulator after triboelectric charging with another insulator is rapidly dissipated with lowered atmospheric pressure. This pressure discharge is consistent with surface ions being evaporated off the surface once their vapor pressure falls below the saturation vapor pressure. A two-phase equilibrium model based on an ideal gas of singly charged ions in equilibrium with a submonolayer adsorbed film was developed to describe the pressure dependence of the surface charge on an insulator. The resulting charge density equation is an electrostatic version of the Langmuir isotherm for adsorbed surface particles, which describes well the experimental observations.
Show less - Date Issued
- 2005
- Identifier
- CFE0000755, ucf:46592
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000755
- Title
- PRESSURE LOSSES EXPERIENCED BY LIQUID FLOW THROUGH PDMS MICROCHANNELS WITH ABRUPT AREA CHANGES.
- Creator
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Wehking, Jonathan, Chew, Larry, University of Central Florida
- Abstract / Description
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Given the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant...
Show moreGiven the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant depth of 104 micrometers. The simplified Bernoulli equations for uniform, steady, incompressible, internal duct flow were used to compare flow through these microchannels to macroscale theory predictions for pressure drop. One major advantage of the channel design (and subsequent experimental set-up) was that pressure measurements could be taken locally, directly before and after the test section of interest, instead of globally which requires extensive corrections to the pressure measurements before an accurate result can be obtained. Bernoulli's equation adjusted for major head loses (using Darcy friction factors) and minor head losses (using appropriate K values) was found to predict the flow behavior within the calculated theoretical uncertainty (~12%) for all 150+ microchannels tested, except for sizes that pushed the aspect ratio limits of the manufacturing process capabilities (microchannels fabricated via soft lithography using PDMS). The analysis produced conclusive evidence that liquid flow through microchannels at these relative channel sizes and Reynolds numbers follow macroscale predictions without experiencing any of the reported anomalies expressed in other microfluidics research. This work also perfected the delicate technique required to pierce through the PDMS material and into the microchannel inlets, exit and pressure ports without damaging the microchannel. Finally, two verified explanations for why prior researchers have obtained poor agreement between macroscale theory predictions and tests at the microscale were due to the presence of bubbles in the microchannel test section (producing higher than expected pressure drops), and the occurrence of localized separation between the PDMS slabs and thus, the microchannel itself (producing lower than expected pressure drops).
Show less - Date Issued
- 2008
- Identifier
- CFE0002289, ucf:47865
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002289
- Title
- THE REMOVAL OF MOTION ARTIFACTS FROM NON-INVASIVE BLOOD PRESSURE MEASUREMENTS.
- Creator
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Thakkar, Paresh, Weeks, Arthur, University of Central Florida
- Abstract / Description
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Modern Automatic Blood Pressure Measurement Techniques are based on measuring the cuff pressure and on sensing the pulsatile amplitude variations. These measurements are very sensitive to motion of the patient or the surroundings where the patient is. The slightest unexpected movements could offset the readings of the automatic Blood Pressure meter by a large amount or render the readings totally meaningless. Every effort must be taken to avoid subjecting the body of the patient or the...
Show moreModern Automatic Blood Pressure Measurement Techniques are based on measuring the cuff pressure and on sensing the pulsatile amplitude variations. These measurements are very sensitive to motion of the patient or the surroundings where the patient is. The slightest unexpected movements could offset the readings of the automatic Blood Pressure meter by a large amount or render the readings totally meaningless. Every effort must be taken to avoid subjecting the body of the patient or the patient's surroundings to motion for obtaining a reliable reading. But there are situations in which we need Blood Pressure Measurements with the patient or his surroundings in motion; for instance in an ambulance while a patient is being transported to a hospital. In this thesis, we present a technique to reduce the effect of motion artifact from Blood Pressure measurements. We digitize the blood pressure waveform and use Digital Signal Processing Techniques to process the corrupted waveform. We use the differences in frequency spectra of the Blood Pressure signal and motion artifact noise to remove the motion artifact noise. The motion artifact noise spectrum is not very well defined, since it may consist of many different frequency components depending on the kind of motion. The Blood Pressure signal is more or less a periodic signal. That translates to periodicity in the frequency domain. Hence, we designed a digital filter that could take advantage of the periodic nature of the Blood Pressure Signal waveform. The filter is shaped like a comb with periodic peaks around the signal frequency components. Further processing of the filtered signal: baseline restoration and level shifting help us to further reduce the noise corruption.
Show less - Date Issued
- 2004
- Identifier
- CFE0000324, ucf:46289
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000324
- Title
- MAPPING OF PRESSURE LOSSES THROUGH MICROCHANNELS WITH SWEEPING-BENDS OF VARIOUS ANGLE AND RADII.
- Creator
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hansel, chase, Chew, Larry, University of Central Florida
- Abstract / Description
-
MEMS (Micro Electro Mechanical Systems) have received a great deal of attention in both the research and industrial sectors in recent decades. The broad MEMS category, microfluidics, the study of fluid flow through channels measured on the micrometer scale, plays an important role in devices such as compact heat exchangers, chemical and biological sensors, and lab-on-a-chip devices. Most of the research has been focused on how entire systems operate, both experimentally and through simulation...
Show moreMEMS (Micro Electro Mechanical Systems) have received a great deal of attention in both the research and industrial sectors in recent decades. The broad MEMS category, microfluidics, the study of fluid flow through channels measured on the micrometer scale, plays an important role in devices such as compact heat exchangers, chemical and biological sensors, and lab-on-a-chip devices. Most of the research has been focused on how entire systems operate, both experimentally and through simulation. This paper strives, systematically, to map them through experimentation of the previous to untested realm of pressure loss through laminar square-profile sweeping-bend microchannels. Channels were fabricated in silicone and designed so a transducer could detect static pressure across a very specific length of channel with a desired bend. A wide variety of Reynolds numbers, bend radii, and bend angles were repeatedly tested over long periods in order to acquire a complete picture of pressure loss with in the domain of experimentation. Nearly all situations tested were adequately captured with the exception of some very low loss points that were too small to detect accurately. The bends were found to match laminar straight-duct theory at Reynolds numbers below 30. As Reynolds numbers increased, however, minor losses began to build and the total pressure loss across the bend rose above straight-duct predictions. A new loss coefficient equation was produced that properly predicted pressure losses for sweeping-bends at higher Reynolds numbers; while lower flow ranges are left to laminar flow loss for prediction.
Show less - Date Issued
- 2008
- Identifier
- CFE0002091, ucf:47537
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002091
- Title
- LIQUID CRYSTAL THERMOGRAPHY STUDIES IN WATER POOL BOILING AT SUBATMOSPHERIC PRESSURES.
- Creator
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Talari, Kiran, Kumar, Ranganathan, University of Central Florida
- Abstract / Description
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A pool boiling experimental facility has been designed and built to investigate nucleate pool boiling in water under sub atmospheric pressure. Liquid crystal thermography, a non intrusive technique, is used for the determination of surface temperature distributions. This technique uses encapsulated liquid crystals that reflect definite colors at specific temperatures and viewing angle. Design of the test section is important in this experimental study. Since a new TLC is required for every...
Show moreA pool boiling experimental facility has been designed and built to investigate nucleate pool boiling in water under sub atmospheric pressure. Liquid crystal thermography, a non intrusive technique, is used for the determination of surface temperature distributions. This technique uses encapsulated liquid crystals that reflect definite colors at specific temperatures and viewing angle. Design of the test section is important in this experimental study. Since a new TLC is required for every new set of test conditions, a permanently sealed test section is not an option. The real challenge is to design a leak proof test section which is flexible so that it can be taken apart easily. A plexiglass test section, including a top chamber with an internal volume of 60.9 x 60.9 x 66.4 mm and a bottom plate of 5.5mm thickness is designed and assembled together using quick grips. In the test section, water is boiled using 85.0mm x 16.0mm and 0.050mm thick Fecralloy® as the heating element. The TLC sheet is attached to the bottom plate and the heating element is placed on top of TLC so that the temperature distribution of the heating element during boiling can be interpreted from TLC. A camera system fast enough to capture the thermal response of the TLC and an arrangement to capture both hue of the TLC and growth of the bubble on the same frame has been designed and successfully used. This system allowed recording of position, size and shape of the bubble with synchronized surface temperature. In order to get hue vs. temperature relation, in-situ calibration of the TLC is performed for each test condition with the present experimental setup and lighting conditions. It is found that the calibration curve of the TLC at atmospheric pressure is different from the calibration curve of the same TLC at subatmospheric pressures. The maximum temperature difference between the two curves for the same hue is found to be only 0.6°C. The experiment is run at four different test conditions of subatmospheric pressure and low heat flux. It is run at system pressures of 6.2kPa (0.89Psi) and 8.0kPa (1.16Psi) with a constant heat flux of 1.88kW/m2 and 2.70kW/m2, and a constant heat flux of 2.70kW/m2, 3.662kW/m2 and 4.50 kW/m2 respectively. Analysis of nucleating surface temperatures using thermochromic liquid crystal technique is performed for these test conditions and the bubble dynamics is studied. The temperature distribution is quite varied in each case and the temperature is at its maximum value at the center of the bubble and it decreases radially from the center. The dry spot observed during the experiments indicates that the process of evaporation of the microlayer is dominant at subatmospheric pressures. It is observed that at very low pressure and heat flux the bubble growth is accompanied by the neck formation. Boiling parameters such as bubble frequency, bubble size and contact are also analyzed and a summary of these results for four different test conditions is presented and the relevant differences between the cases are discussed and the effect of increase in pressure and heat flux is noted.
Show less - Date Issued
- 2007
- Identifier
- CFE0001537, ucf:47150
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001537
- Title
- EFFECTS OF VOLUNTARY CONTROL ON PERFORMANCE RESPONSE UNDER STRESS.
- Creator
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Morris, Christina Shawn, Hancock, Peter A., University of Central Florida
- Abstract / Description
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Recent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an...
Show moreRecent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an alternative perspective about these metaphorical, or black box, interpretations and reveals how they may be confounded with respect to the intended real world counterpart. To examine how voluntary human control can influence traditional stress/no-stress research findings, traditional as well as exploratory paradigms were presented. Both noise and time pressure conditions produced significant differences between experimental and control groups on visual discrimination. However, when analogous cash payment-contingency conditions were employed, the traditional stress/no-stress findings were not evident. In addition, a second experiment revealed that this trend of differences (and non-differences) held consistently over 30 minutes of interrupted task performance time. This study indicates the importance of developing more diagnostic measures that include assessments of how the differences between participants' and the generalized operators' goals and motivations may alter results in stressful task environments.
Show less - Date Issued
- 2004
- Identifier
- CFE0000019, ucf:46134
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000019
- Title
- EFFECT OF PRESSURE GRADIENT AND WAKE ON ENDWALL FILM COOLING EFFECTIVENESS.
- Creator
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Rodriguez, Sylvette, Kapat, Jayanta, University of Central Florida
- Abstract / Description
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Endwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching...
Show moreEndwall film cooling is a necessity in modern gas turbines for safe and reliable operation. Performance of endwall film cooling is strongly influenced by the hot gas flow field, among other factors. For example, aerodynamic design determines secondary flow vortices such as passage vortices and corner vortices in the endwall region. Moreover blockage presented by the leading edge of the airfoil subjects the incoming flow to a stagnating pressure gradient leading to roll-up of the approaching boundary layer and horseshoe vortices. In addition, for a number of heavy frame power generation gas turbines that use cannular combustors, the hot and turbulent gases exiting from the combustor are delivered to the first stage vane through transition ducts. Wakes induced by walls separating adjacent transition ducts located upstream of first row vanes also influence the entering main gas flow field. Furthermore, as hot gas enters vane passages, it accelerates around the vane airfoils. This flow acceleration causes significant streamline curvature and impacts lateral spreading endwall coolant films. Thus endwall flow field, especially those in utility gas turbines with cannular combustors, is quite complicated in the presence of vortices, wakes and strong favorable pressure gradient with resulting flow acceleration. These flow features can seriously impact film cooling performance and make difficult the prediction of film cooling in endwall. This study investigates endwall film cooling under the influence of pressure gradient effects due to stagnation region of an axisymmetric airfoil and in mainstream favorable pressure gradient. It also investigates the impact of wake on endwall film cooling near the stagnation region of an airfoil. The investigation consists of experimental testing and numerical simulation. Endwall film cooling effectiveness is investigated near the stagnation region on an airfoil by placing an axisymmetric airfoil downstream of a single row of inclined cylindrical holes. The holes are inclined at 35° with a length-to-diameter ratio of 7.5 and pitch-to-diameter ratio of 3. The ratio of leading edge radius to hole diameter and the ratio of maximum airfoil thickness to hole diameter are 6 and 20 respectively. The distance of the leading edge of the airfoil is varied along the streamwise direction to simulate the different film cooling rows preceding the leading edge of the airfoil. Wake effects are induced by placing a rectangular plate upstream of the injection point where the ratio of plate thickness to hole diameter is 6.4, and its distance is also varied to investigate the impact of strong and mild wake on endwall film cooling effectiveness. Blowing ratio ranged from 0.5 to 1.5. Film cooling effectiveness is also investigated under the presence of mainstream pressure gradient with converging main flow streamlines. The streamwise pressure distribution is attained by placing side inserts into the mainstream. The results are presented for five holes of staggered inclined cylindrical holes. The inclination angle is 30° and the tests were conducted at two Reynolds number, 5000 and 8000. Numerical analysis is employed to aid the understanding of the mainstream and coolant flow interaction. The solution of the computational domain is performed using FLUENT software package from Fluent, Inc. The use of second order schemes were used in this study to provide the highest accuracy available. This study employed the Realizable κ-ε model with enhance wall treatment for all its cases. Endwall temperature distribution is measured using Temperature Sensitive Paint (TSP) technique and film cooling effectiveness is calculated from the measurements and compared against numerical predictions. Results show that the characteristics of average film effectiveness near the stagnation region do not change drastically. However, as the blowing ratio is increased jet to jet interaction is enhanced due to higher jet spreading resulting in higher jet coverage. In the presence of wake, mixing of the jet with the mainstream is enhanced particularly for low M. The velocity deficit created by the wake forms a pair of vortices offset from the wake centerline. These vortices lift the jet off the wall promoting the interaction of the jet with the mainstream resulting in a lower effectiveness. The jet interaction with the mainstream causes the jet to lose its cooling capabilities more rapidly which leads to a more sudden decay in film effectiveness. When film is discharged into accelerating main flow with converging streamlines, row-to-row coolant flow rate is not uniform leading to varying blowing ratios and cooling performance. Jet to jet interaction is reduced and jet lift off is observed for rows with high blowing ratio resulting in lower effectiveness.
Show less - Date Issued
- 2008
- Identifier
- CFE0002425, ucf:47769
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002425
- Title
- LOW REYNOLDS NUMBER WATER FLOW CHARACTERISTICS THROUGH RECTANGULAR MICRO DIFFUSERS/NOZZLES WITH A PRIMARY FOCUS ON MAJOR/MINOR PRESSURE LOSS, STATIC PRESSURE RECOVERY, AND FLOW SEPARATION.
- Creator
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Hallenbeck, Kyle, Chew, Larry, University of Central Florida
- Abstract / Description
-
The field of microfluidics has recently been gathering a lot of attention due to the enormous demand for devices that work in the micro scale. The problem facing many researchers and designers is the uncertainty in using macro scaled theory, as it seems in some situations they are incorrect. The general idea of this work was to decide whether or not the flow through micro diffusers and nozzles follow the same trends seen in macro scale theory. Four testing wafers were fabricated using PDMS...
Show moreThe field of microfluidics has recently been gathering a lot of attention due to the enormous demand for devices that work in the micro scale. The problem facing many researchers and designers is the uncertainty in using macro scaled theory, as it seems in some situations they are incorrect. The general idea of this work was to decide whether or not the flow through micro diffusers and nozzles follow the same trends seen in macro scale theory. Four testing wafers were fabricated using PDMS soft lithography including 38 diffuser/nozzle channels a piece. Each nozzle and diffuser consisted of a throat dimension of 100μm x 50μm, leg lengths of 142μm, and half angles varying from 0o – 90o in increments of 5o. The flow speeds tested included throat Reynolds numbers of 8.9 – 89 in increments of 8.9 using distilled water as the fluid. The static pressure difference was measured from the entrance to the exit of both the diffusers and the nozzles and the collected data was plotted against a fully attached macro theory as well as Idelchik's approximations. Data for diffusers and nozzles up to HA = 50o hints at the idea that the flow is neither separating nor creating a vena contracta. In this region, static pressure recovery within diffuser flow is observed as less than macro theory would predict and the losses that occur within a nozzle are also less than macro theory would predict. Approaching a 50o HA and beyond shows evidence of unstable separation and vena contracta formation. In general, it appears that there is a micro scaled phenomenon happening in which flow gains available energy when the flow area is increased and looses available energy when the flow area decreases. These new micro scaled phenomenon observations seem to lead to a larger and smaller magnitude of pressure loss respectively.
Show less - Date Issued
- 2008
- Identifier
- CFE0002391, ucf:47772
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002391
- Title
- THE EFFECT OF COMBAT EXERCISES ON CARDIOVASCULAR RESPONSE: AN EXPLORATORY STUDY.
- Creator
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Gantt, MeLisa, Sole, Mary Lou, University of Central Florida
- Abstract / Description
-
PURPOSE: Hypertension (HTN) affects one in every three adults in the United States. Often associated with the older population, this silent killer has emerged in an unsuspecting group, young military soldiers. With the rapid succession of multiple deployments, long intervals between blood pressure (BP) assessments, and the absence of cardiovascular (CV) measures during the pre and post deployment health screenings; soldiers may be at higher risk for HTN than their civilian counterparts of the...
Show morePURPOSE: Hypertension (HTN) affects one in every three adults in the United States. Often associated with the older population, this silent killer has emerged in an unsuspecting group, young military soldiers. With the rapid succession of multiple deployments, long intervals between blood pressure (BP) assessments, and the absence of cardiovascular (CV) measures during the pre and post deployment health screenings; soldiers may be at higher risk for HTN than their civilian counterparts of the same age. The purpose of this study was to explore real-time continuous CV measures of soldiers before, during, and after exposure to a simulated combat stressor as well as to assess which personal characteristics played a significant role. METHODS: Applying the Allostasis/Allostatic Load theoretical framework, a repeated measure quasi-experimental design was used to compare the CV measures of two groups: one exposed to a physical combat stressor (experimental) and the other exposed to a psychological combat stressor (control). A convenience sample of 60 college Army Reserve Officer Training Corps cadets were fitted with Tiba Medical Ambulo 2400 ambulatory BP monitors for 48 continuous hours. Several CV indices were analyzed using one-way Analysis of Variance (ANOVA), paired t-test, and independent sample t-test. Four instruments (Participant Information Sheet, State-Trait Anxiety Inventory, Paintball Perceived Stress Questionnaire, and Army Physical Fitness Test) were used to assess which characteristics played the most significant role in the CV response. RESULTS: Demographic characteristics between the two 30-cadet groups were not statistically different, with the exception of deployment history (experimental = 4, control= 0). Hours after the stress exposure, subjects in the experimental group had a higher mean awake systolic blood pressure (SBP) when compared to the control group (113.76 mm Hg vs 102.98 mm Hg, p= 009). When assessing pre and post stressor morning BP surge and evening BP decline, the control group showed the biggest change. Significant bivariate correlations (p < .05) found that: Females consistently had higher pulse rates (PR) throughout each of the phases. Age positively correlated with elevated BP during the stressor, and increased morning BP surge post stressor. African Americans had higher sleep BPs pre stressor, and decreased SBP recovery post stressor; Hispanics had higher PRs during and after the stressor. Waist circumference positively correlated with elevated BP morning surge pre stressor but, body mass index (BMI) positively correlated with elevated BP morning surge post stressor as well as elevated BP during the stressor. Family history of HTN played no significant role; however, deployment history correlated with mean awake SBP post stressor. Trait anxiety scores negatively correlated with SBP recovery while state anxiety scores positively correlated with post stressor awake mean arterial pressure and evening SPB decline. Perceived stress during the stressor negatively correlated with post stressor SBP morning surge with females reporting higher anxiety and stress. Finally, Army Physical Fitness (APFT) total scores as well as APFT run scores negatively correlated with pre and post stressor sleep PRs. DISCUSSION/IMPLICATIONS: Age, female gender, African American descent, Hispanic ethnicity, waist circumference, BMI, previous deployment history, level of fitness and the psychological stress state during and after a stressor played significant roles in soldiersÂÂÂÂ' CV response. SBP was the most dynamic and informative of the CV indices and a psychological stressor was comparable to a physical stressor when observing the residual effect of stress. If a combat exercise was enough of a stressor to produce residual CV effects that lasted well into following morning, the residual effect of a lengthy strenuous deployment may be alarming. This study not only provided a snapshot of the CV health of incoming young soldiers, but also provided evidence to support policy change regarding the implementation of regular CV health assessments before and after deployment.
Show less - Date Issued
- 2010
- Identifier
- CFE0003390, ucf:48458
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003390
- Title
- FINITE DEPTH SEEPAGE BELOW FLAT APRON WITH END CUTOFFS AND A DOWNSTREAM STEP.
- Creator
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Jain, Arun, Reddi, Lakshmi, University of Central Florida
- Abstract / Description
-
Hydraulic structures with water level differences between upstream and downstream are subjected to seepage in foundation soils. Two sources of weakness are to be guarded against: (1) percolation or seepage may cause under-mining, resulting in the collapse of the whole structure, and (2) the floor of the apron may be forced upwards, owing to the upward pressure of water seeping through pervious soil under the structure. Many earlier failures of hydraulic structures have been reported due to...
Show moreHydraulic structures with water level differences between upstream and downstream are subjected to seepage in foundation soils. Two sources of weakness are to be guarded against: (1) percolation or seepage may cause under-mining, resulting in the collapse of the whole structure, and (2) the floor of the apron may be forced upwards, owing to the upward pressure of water seeping through pervious soil under the structure. Many earlier failures of hydraulic structures have been reported due to these two reasons. The curves and charts prepared by Khosla, Bose, and Taylor still form the basis for the determination of uplift pressure and exit gradient for weir apron founded on pervious soil of infinite depth. However, in actual practice, the pervious medium may be of finite depth owing to the occurrence of a clay seam or hard strata at shallow depths in the river basin. Also, a general case of weir profile may consist of cutoffs, at the two ends of the weir apron. In addition to the cutoffs, pervious aprons are also provided at the downstream end in the form of (i) inverted filter, and (ii) launching apron. These pervious aprons may have a thickness of 2 ft. to 5 ft. In order to accommodate this thickness, the bed adjacent to the downstream side of downstream cutoff has to be excavated. This gives rise to the formation of step at the downstream end. Closed form theoretical solutions for the case of finite depth seepage below weir aprons with end cutoffs, with a step at the downstream side are obtained in this research. The parameters studied are : (i) finite depth of pervious medium, (ii) two cut offs at the ends, and (iii) a step at the downstream end. The resulting implicit equations, containing elliptic integrals of first and third kind, have been used to obtain various seepage characteristics. The results have been compared with existing solutions for some known boundary conditions. Design curves for uplift pressure at key points, exit gradient factor and seepage discharge factor have been presented in terms of non-dimensional floor profile ratios.
Show less - Date Issued
- 2011
- Identifier
- CFE0003898, ucf:48751
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003898
- Title
- Effects of a 10-Week Introductory Judo Course on Postural Control During Reactionary Bilateral Gripping Task With Varied Stances and Lower Body Power Performance.
- Creator
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Muddle, Tyler, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, University of Central Florida
- Abstract / Description
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PURPOSE: The purpose of the present study is twofold: 1.) Examine the effects of 10-weeks of an introductory judo course on postural control during maximal bilateral isometric handgrip testing using different stance conditions and lower body power performance, and 2.) To analyze the relationship between maximal bilateral handgrip exertions on postural control during varied stance conditions. METHODS: Twenty recreationally active men and women divided into two an experimental group, (JDO) (n =...
Show morePURPOSE: The purpose of the present study is twofold: 1.) Examine the effects of 10-weeks of an introductory judo course on postural control during maximal bilateral isometric handgrip testing using different stance conditions and lower body power performance, and 2.) To analyze the relationship between maximal bilateral handgrip exertions on postural control during varied stance conditions. METHODS: Twenty recreationally active men and women divided into two an experimental group, (JDO) (n = 10; 21.70 (&)#177; 3.83 y; 169.91 (&)#177; 6.01 cm; 73.89 (&)#177; 12.10 kg; 19.01 (&)#177; 8.06% BF), and a control group, (CON) (n = 10; 21.50 (&)#177; 2.84 y; 170.06 (&)#177; 8.28 cm; 76.62 (&)#177; 12.03 kg; 22.41 (&)#177; 6.64% BF), participated in this study. Both groups completed pre-testing, performing nine randomly assigned experimental trials measuring center of pressure (COP) variables during the performance of a bilateral reactionary gripping task using varied stance conditions. Each trial consisted of bilateral maximal voluntary contractions (MVC) measured simultaneously with a handgrip dynamometer, three times with a neutral (N), dominant foot forward (D), and non-dominant (ND) foot forward stance. Furthermore, participants performed three bilateral countermovement jumps (CMJ) trials. All trials were completed while standing on a portable force platform, which was used, in conjunction with corresponding software, to track COP amplitude in the mediolateral (COPML) and anteroposterior (COPAP) directions, COP mean velocity (MV), and COP area (AREA) while gripping the dynamometer, and ground reaction forces, peak force (CMJPKF), peak power (CMJPP), and rate of power development (CMJRPD), during CMJ performance. Subjects were instructed to grasp the dynamometers as forcefully as possible for ?5-sec during each trial. All trials were separated by a recovery period of 60-sec. A Waterloo Handedness and Footedness Questionnaire was used to determine subject upper and lower body laterality. Participants repeated the testing protocol following the conclusion of the 10-week course. RESULTS: No significant interactions were observed in MVC strength of the DOM and NON hands during any of the three stance conditions following the 10-week judo course. Furthermore, no significant interactions were observed for any of the COP variables. However, a significant main effect of stance was observed for COPML, MV, and AREA. Results did reveal that CMJPP significantly improved in the JDO group (PRE: 3584.70 (&)#177; 716.59W - POST: 3750.10 (&)#177; 699.61W) following the 10-week judo course, while no change was observed in the CON group (PRE: 3693.10 (&)#177; 1083.77W (-) POST: 3654.40 (&)#177; 1023.94W). However, no change was seen in CMJPKF or CMJRPD. CONCLUSIONS: The results of this investigation indicate that 10-weeks of an introductory judo course may increase CMJPP, however, has no effect on postural control or bilateral MVC strength of the DOM and NON hand during varied stance conditions. Furthermore, results reveal that bilateral MVC exertion has no influence on postural control performed during varied stance conditions.
Show less - Date Issued
- 2016
- Identifier
- CFE0006148, ucf:51157
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006148
- Title
- High Pressure Micro-Spectroscopy of Biological Assemblies and Cells.
- Creator
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Park, Sang, Schulte, Alfons, Chow, Lee, Luo, Weili, Phanstiel, Otto, University of Central Florida
- Abstract / Description
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Functional properties of living cells depend on the thermodynamic variables such as temperature and pressure. A unique tool to investigate volume effects on structure and metabolism of the cell and biomolecules is pressure perturbation. We have developed a new setup that enables micro-spectroscopy and optical imaging of individual live cells at variable pressure from 0.1 to 400 MPa. Following characterization of the setup, pressure and temperature effects on the secondary structure of the...
Show moreFunctional properties of living cells depend on the thermodynamic variables such as temperature and pressure. A unique tool to investigate volume effects on structure and metabolism of the cell and biomolecules is pressure perturbation. We have developed a new setup that enables micro-spectroscopy and optical imaging of individual live cells at variable pressure from 0.1 to 400 MPa. Following characterization of the setup, pressure and temperature effects on the secondary structure of the peptide Poly-L-glutamic acid (PGA) in deuterated water buffer solution were investigated. The amide I band of PGA is sensitive to pressure and temperature, and by spectral deconvolution, we determined the relative contributions due to the ?-helix and random coil conformations. The population of ?-helix increases with increasing pressure. Pressure effects on single red blood cells and the intracellular protein hemoglobin were studied by micro-Raman spectroscopy. In particular, we observed a shift in the frequency of the iron-histidine vibrational band in both the intracellular hemoglobin and hemoglobin in solutions. The iron-histidine mode is a sensitive structural marker of the crucial iron-protein linkage in heme proteins. The pressure dependent shift suggests a conformational change of the heme environment. This finding was further supported by micro-absorption measurements at variable pressure.In additional experiments, Raman spectroscopy was employed to probe molecular changes that occurred in hemoglobin in erythrocytes infected with the malaria parasite Plasmodium falciparum. The spectra of infected cells indicated that hemoglobin degradation can be correlated with the stages of the parasite multiplication cycle. The research was further extended towards probing size and shape changes of individual cells with pressure. The lateral diameter in yeast cells was observed to decrease with pressure in a reversible way. These results suggest that transport of the intra-cellular water may play a significant role for volume changes.In summary, pressure changes were shown to induce conformational changes in proteins and shape changes in yeast cells. A Raman technique was developed to monitor the states of Plasmodium falciparum multiplication cycle within a red blood cell.
Show less - Date Issued
- 2012
- Identifier
- CFE0004637, ucf:49909
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004637
- Title
- A STUDY OF SYNGAS OXIDATION AT HIGH PRESSURES AND LOW TEMPERATURES.
- Creator
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Kalitan, Danielle, Petersen, Eric, University of Central Florida
- Abstract / Description
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Ignition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825
Show moreIgnition and oxidation characteristics of CO/H2, H2/O2 and CO/H2/CH4/CO2/Ar fuel blends in air were studied using both experimental and computer simulation methods. Shock-tube experiments were conducted behind reflected shock waves at intermediate temperatures (825 < T < 1400 K) for a wide range of pressures (1 < P < 45 atm). Results of this study provide the first undiluted fuel-air ignition delay time experiments to cover such a wide range of syngas mixture compositions over the stated temperature range. Emission in the form of chemiluminescence from the hydroxyl radical (OH*) transition near 307 nm and the pressure behind the reflected shock wave were used to monitor reaction progress from which ignition delay times were determined. In addition to the experimental analysis, chemical kinetics calculations were completed to compare several chemical kinetics mechanisms to the new experimental results. Overall, the models were in good agreement with the shock-tube data, especially at higher temperatures and lower pressures, yet there were some differences between the models at higher pressures and the lowest temperatures, in some cases by as much as a factor of five. In order to discern additional information from the chemical kinetics mechanisms regarding their response to a wide range of experimental conditions, ignition delay time and reaction rate sensitivity analyses were completed at higher and lower temperatures and higher and lower pressures. These two sensitivity analyses allow for the identification of the key reactions responsible for ignition. The results of the sensitivity analysis indicate that the ignition-enhancing reaction H + O2 = O + OH and hydrogen oxidation kinetics in general were most important regardless of mixture composition, temperature or pressure. However, lower-temperature, higher-pressure ignition delay time results indicate additional influence from HO2- and CO- containing reactions, particularly the well-known H + O + M = HO2 + M reaction and also the CO + O + M = CO2 + M and CO + HO2 = CO2 + OH reactions. Differences in the rates of the CO-related reactions are shown to be the cause of some of the discrepancies amongst the various models at elevated pressures. However, the deviation between the models and the experimental data at the lowest temperatures could not be entirely explained by discrepancies in the current rates of the reactions contained within the mechanisms. Additional calculations were therefore performed to gain further understanding regarding the opposing ignition behavior for calculated and measured ignition delay time results. Impurities, friction induced ionization, static charge accumulation, boundary layer effects, wall reaction effects, and revised chemical kinetics were all considered to be possible mechanisms for the model and measured data disparity. For the case of wall-reaction effects, additional shock-tube experiments were conducted. For the remaining effects listed above, only detailed calculations were conducted. Results from this preliminary anomaly study are at this time inconclusive, but likely avenues for future study were identified. Additional kinetics calculations showed that the large difference between the experimental data and the chemical kinetics models predictions at low temperatures can be explained by at least one missing reaction relevant to low-temperature and high-pressure experimental conditions involving the formation of H2O2, although further study beyond the scope of this thesis is required to prove this hypothesis both theoretically and experimentally.
Show less - Date Issued
- 2007
- Identifier
- CFE0001862, ucf:47414
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001862
- Title
- STRUCTURAL HEALTH MONITORING OF COMPOSITE OVERWRAPPED PRESSURE VESSELS.
- Creator
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Letizia, Luca, Catbas, F. Necati, University of Central Florida
- Abstract / Description
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This work is focusing to study the structural behavior of Composite Overwrapped Pressure Vessels (COPVs). These COPVs are found in many engineering applications. In the aerospace field, they are installed onto spaceships and aid the reorientation of the spacecraft in very far and airless, therefore frictionless, orbits to save energy and fuel. The intent of this research is to analyze the difference in performance of both perfectly intact and purposely damaged tanks. Understanding both the...
Show moreThis work is focusing to study the structural behavior of Composite Overwrapped Pressure Vessels (COPVs). These COPVs are found in many engineering applications. In the aerospace field, they are installed onto spaceships and aid the reorientation of the spacecraft in very far and airless, therefore frictionless, orbits to save energy and fuel. The intent of this research is to analyze the difference in performance of both perfectly intact and purposely damaged tanks. Understanding both the source and location of a structural fault will help NASA engineers predict the performance of COPVs subject to similar conditions, which could prevent failures of important missions. The structural behavior of six tanks is investigated by means of experimental modal analysis. Knowledge of statistical signal processing methods allows to sort out and extract meaningful features from the data as to gain understanding of the performance of the structures. Structural identification is carried out using Narrow Band and Broad Band algorithms. A comparison through correlation tables and figures presents the differences in natural frequencies, mode shapes and damping ratios of all structures. A careful analysis displays the deviation of these modal parameters in the damaged tanks, highlighting the evident structural defects.
Show less - Date Issued
- 2016
- Identifier
- CFH2000069, ucf:45514
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000069
- Title
- SODIUM (NA) LEVELS IN DRINKING WATER (H20) AND DEVELOPMENT OF HYPERTENSION IN CHILDREN.
- Creator
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Schiffman, Sara, Bushy, Angeline, University of Central Florida
- Abstract / Description
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This integrative review of the literature focused on sodium (Na) content in drinking water (H2O) supplies and the subsequent effect on blood pressure levels in children. Studies for this review were drawn from the Cumulative Index of Nursing and Allied Health, PubMED, Science and Technology Databases, PsychInfo, United States (US) Environmental Protection Agency (EPA) and EPA in Florida websites. Criterion for inclusion in the data base searches were hypertension, high blood pressure, sodium...
Show moreThis integrative review of the literature focused on sodium (Na) content in drinking water (H2O) supplies and the subsequent effect on blood pressure levels in children. Studies for this review were drawn from the Cumulative Index of Nursing and Allied Health, PubMED, Science and Technology Databases, PsychInfo, United States (US) Environmental Protection Agency (EPA) and EPA in Florida websites. Criterion for inclusion in the data base searches were hypertension, high blood pressure, sodium in drinking water, drinking water salinity, children or preg*. Subsequently, further article selection criteria included children (under 18 years of age)and published in the English language (N=59). Findings of the review as summarized in this thesis could guide nursing research, education, policy and practice related to primary, secondary and tertiary interventions associated with sodium levels in drinking as a contributing factor to blood pressure levels in children.
Show less - Date Issued
- 2013
- Identifier
- CFH0004469, ucf:45123
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004469
- Title
- NON-INVASIVE POSITIVE PRESSURE VENTILATION (NPPV): ITS USES, COMPLICATIONS, & IMPLICATIONS WITHIN NURSING PRACTICE IN ACUTE CARE SETTINGS.
- Creator
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Marano, Alexis, Sole, Mary, University of Central Florida
- Abstract / Description
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The use of noninvasive positive pressure ventilation (NPPV) in acute care settings has drastically increased within the past 20 years. Research has indicated that NPPV is equally as effective as traditional mechanical ventilation(MV) in treating acute exacerbations of chronic pulmonary obstructive disease (COPD) and cardiogenic pulmonary edema. Furthermore, the risk of complication from NPPV is much lower than MV, in terms of ventilator-associated pneumonia and sepsis. It is imperative for...
Show moreThe use of noninvasive positive pressure ventilation (NPPV) in acute care settings has drastically increased within the past 20 years. Research has indicated that NPPV is equally as effective as traditional mechanical ventilation(MV) in treating acute exacerbations of chronic pulmonary obstructive disease (COPD) and cardiogenic pulmonary edema. Furthermore, the risk of complication from NPPV is much lower than MV, in terms of ventilator-associated pneumonia and sepsis. It is imperative for the nurse to understand the various indications, interfaces, and potential complications associated with NPPV use. In addition to treating acute exacerbations of COPD and cardiogenic pulmonary edema, NPPV has been used for prevention of reintubation, palliative care, and status asthmaticus. Furthermore, NPPV could be delivered through various interfaces, such as nasal, facial, and helmet. Each of these interfaces could eventually cause complications for the patient, such as skin ulceration and sepsis. However, there is limited amount of research available discussing the role of the nurse in caring for the patient with NPPV. There are no standardized guidelines established to assist the nurse in this care, in terms of interface selection, prevention of complications, and staffing patterns. Several recommendations are presented at the end of this thesis to guide future nursing research, education, and clinical practice, such as exploring the role of oral care and education for NPPV patients.
Show less - Date Issued
- 2012
- Identifier
- CFH0004276, ucf:44937
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004276
- Title
- PRESSURE DROP AND ENDWALL HEAT TRANSFER EFFECTS OF POROUS TURBULATORS IN A RECTANGULAR CHANNEL.
- Creator
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Pent, Jared, Kapat, Jay, University of Central Florida
- Abstract / Description
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This study examines the local and averaged endwall heat transfer effects of a staggered array of porous pin fins within a rectangular channel. The porous pin fins were made from aluminum and had a pore density of 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates and presented in terms of the friction factor. Local heat transfer coefficients on the endwall were measured using Thermochromic Liquid Crystal (TLC) sheets recorded with a...
Show moreThis study examines the local and averaged endwall heat transfer effects of a staggered array of porous pin fins within a rectangular channel. The porous pin fins were made from aluminum and had a pore density of 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates and presented in terms of the friction factor. Local heat transfer coefficients on the endwall were measured using Thermochromic Liquid Crystal (TLC) sheets recorded with a charge-coupled device (CCD) camera. Static and total pressure measurements were taken at the entrance and exit of the test section to determine the overall pressure drop through the channel and explain the heat transfer trends through the channel. Results are presented for Reynolds numbers between 25000 and 130000 and a blockage ratio (blocked channel area divided by open channel area) of 50%. All results were compared to the corresponding results obtained using solid pins. All experiments were carried out in a 150 mm by 500 mm channel with an X/D of 1.72, a Y/D of 2.0, and a Z/D of 1.72 for the porous pins. It was found that for the range of Reynold's numbers tested in this study, the porous pin array consistently resulted in a larger friction factor, and therefore greater losses than a geometrically similar array of solid pins. The friction factors for the solid pin array were between 9.5 and 10.5, similar to the results found in the literature. For the porous pins, however, the friction factors were significantly increased as the Reynold's number increased, reaching as high as 15.3 at the highest Reynold's number tested. The heat transfer enhancement for the porous pins was found to be between 150 and 170% while the solid pins resulted in a heat transfer enhancement between 190 and 230%.
Show less - Date Issued
- 2009
- Identifier
- CFE0002819, ucf:48085
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002819
- Title
- INTEGRATION OF A NANOSTRUCTURE EMBEDDED THERMORESPONSIVE POLYMER FOR MICROFLUIDIC APPLICATIONS.
- Creator
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Londe, Ghanashyam, Cho, Hyoung Jin, University of Central Florida
- Abstract / Description
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This work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature...
Show moreThis work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature) of a unique switchable, nanostructured, thermoresponsive surface consisting of silica nanoparticles and the thermoresponsive polymer, Poly(N-isopropylacrylamide ) (PNIPAAm) which changes its wetting angle upon heating. Important metrics such as the absolute lower critical solution temperature, threshold & saturation temperatures and gain are modeled and quantified by mathematical expressions. Based on the modeling, a heat source for the thermoresponsive surface was integrated on the glass substrate itself to create a fully functional smart surface. The design and fabrication of a smart platform consisting of the switchable, nanostructured, thermoresponsive surface with an integrated gold microheater for wettability control and its time response analysis was conducted. The insight gained into the behavior of the thermoresponsive surface by using the analytical model, aided the effort in the effective integration of the surface into a microfluidic channel for flow regulation applications. The implementations of novel microfluidic flow regulator concepts were tested. The aim is to integrate a regulator function to a channel surface utilizing the layer-by-layer (LBL) deposition technique. The characterization and pressure differential study of the microfluidic regulators was carried out on simple straight microchannels which were selectively coated with the thermoresponsive surface. Theoretical and experimental studies were performed to determine the important characteristic parameters including capillary, Weber and Reynolds numbers. The pressure differential data was used to develop critical operating specifications. This work lays out a new microfluidic device concept consisting of a channel with a built-in regulatory function.
Show less - Date Issued
- 2008
- Identifier
- CFE0002368, ucf:47786
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002368
- Title
- HIGH PRESSURE AND MICRO-SPECTROSCOPIC STUDIES OF SINGLE LIVING ERYTHROCYTES AND THE INTRAERYTHROCYTIC MULTPLICATION CYCLE OF PLASMODIUM FALCIPARUM.
- Creator
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ARORA, SILKI, SCHULTE, ALFONS, University of Central Florida
- Abstract / Description
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A novel experimental approach for micro-absorption spectroscopy and high-pressure microscopy of single cells is developed and applied to the investigation of morphological, volume, and spectroscopic changes in healthy red blood cells (RBCs) and erythrocytes infected with the malaria parasite Plasmodium falciparum. Through real-time optical imaging of individual erythrocytes (size ~ 7 microns) we determine the change in volume over the pressure range from 0.1 to 210 MPa. The lateral diameter...
Show moreA novel experimental approach for micro-absorption spectroscopy and high-pressure microscopy of single cells is developed and applied to the investigation of morphological, volume, and spectroscopic changes in healthy red blood cells (RBCs) and erythrocytes infected with the malaria parasite Plasmodium falciparum. Through real-time optical imaging of individual erythrocytes (size ~ 7 microns) we determine the change in volume over the pressure range from 0.1 to 210 MPa. The lateral diameter of healthy RBCs decreases reversibly with pressure with an approximate slope of 0.015 microns / MPa. In infected cells, clear differences in the deformability and between the compression and decompression curves are observed. The results are discussed with respect to the elasticity of the phospholipid membrane and the spectrin molecular network. Employing micro-absorption spectroscopy with spatial resolution of 1.4 microns in the lateral and 3.6 microns in the axial direction the visible absorption spectrum of hemoglobin in a single red blood cell is measured under physiological conditions. The spectra of cells infected with the malaria parasite show changes in peak positions and relative intensities in the Soret and the alpha- and beta-bands. These indicate hemoglobin degradation that can be correlated with the stages of the parasite multiplication cycle and can be used as a potential diagnostic marker. The research is further extended towards the understanding of pressure effects on the ligand binding kinetics to heme proteins. For a well characterized reaction at ambient pressure, CO binding to myoglobin in solution, we investigate the transient absorption following laser flash photolysis over eight decades in time at variable pressure and temperature. The data demonstrate that pressure significantly affects the amplitudes (not just the rates) of the component processes. The amplitude of the geminate process increases with pressure corresponding to a smaller escape fraction of ligands into the solvent and a smaller inner barrier.
Show less - Date Issued
- 2011
- Identifier
- CFE0004039, ucf:49157
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004039
