Academic literature on the topic 'Centrifugation'

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Journal articles on the topic "Centrifugation"

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Daramola, James Ola. "Effect of Centrifugation on Motility, Sperm Capacitation and Acrosome Reaction in Soy Bean and Avocado Seed Milk Extenders of Cryopreserved Goat Spermatozoa." Agricultura Tropica et Subtropica 50, no. 1 (March 1, 2017): 13–18. http://dx.doi.org/10.1515/ats-2017-0002.

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Abstract Removal of seminal plasma by centrifugation (0 centrifugation, 1 centrifugation, 2 centrifugations, 3 centrifugations) and preservation in two different tris-extenders viz., avocado seed milk (ASM) and soy bean milk (SBM) based extenders were studied for their ability to support motility, in vitro capacitation and acrosome reaction of spermatozoa obtained from West African Dwarf (WAD) goat bucks during cryopreservation. Semen samples collected with the aid of artificial vagina were centrifuged for one, two and three times. The centrifuged samples were diluted with the two tris-extenders each containing 20 mL of avocado seed milk and soybean milk and cryopreserved for 30 days. The results showed higher (P < 0.05) sperm motility (P < 0.05) with increased centrifugation times. Spermatozoa that were centrifuged had higher (P < 0.05) percentage of acrosome reaction and capacitation with increased centrifugation times compared to the control. Optimal improvement in these parameters was obtained with increased centrifugation times. The findings revealed that removal of seminal plasma by centrifugation improved sperm quality of WAD goat bucks during cryopreservation and optimum improvement was achieved consistently with 3 centrifugations.
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Gallagher, Sean R. "Centrifugation." Current Protocols Essential Laboratory Techniques 00, no. 1 (January 2008): 5.1.1–5.1.16. http://dx.doi.org/10.1002/9780470089941.et0501s00.

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Jo, Chris H., Young Hak Roh, Ji Eun Kim, Sue Shin, and Kang Sup Yoon. "Optimizing Platelet-Rich Plasma Gel Formation by Varying Time and Gravitational Forces During Centrifugation." Journal of Oral Implantology 39, no. 5 (October 1, 2013): 525–32. http://dx.doi.org/10.1563/aaid-joi-d-10-00155.

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Despite the increasing clinical use of topical platelet-rich plasma (PRP) to enhance tissue healing and regeneration, there is no properly standardized method of autologous PRP gel preparation. This study examined the effect of the centrifugation time and gravitational force (g) on the platelet recovery ratio of PRP and determined the most effective centrifugation conditions for preparing PRP. Two-step centrifugations for preparing PRP were used in 39 subjects who had consented prior to the study's start. The separating centrifugation (Step 1, used to separate whole blood into its two main components: red blood cells and plasma) was tested from 500g to 1900g at 200g increments for 5 minutes (min), and from 100g to 1300g at 200g increments for 10 minutes. After separating centrifugation, upper plasma layer was transferred to another plain tube for the condensation centrifugation and remaining lower cell layer was discarded. The condensation centrifugation (Step 2, used to condense the platelets in the separated plasma) was tested at 1000g for 15 min, 1500g for 15 min, 2000g for 5 min and 3000g for 5 min, additionally at 1000g for 10 min and 1500g for 10 min. Platelet gelation was induced by adding 10% calcium gluconate to final PRP with volume ratio of 1:10. The optimal separating centrifugation conditions were followed by 900g for 5 minutes and the condensation conditions were followed by 1500g for 15 minutes, of which recovery ratios were 92.0 ± 3.1% and 84.3 ± 10.0%, respectively.
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Yuliandari, Aisyara, Prima Octafia Damhuri, Tiur Sherly Margaretta, Sarah Ester Priskilla, and Hartini H. "EVALUATION OF PLATELET RICH PLASMA (PRP) PREPARATION PROCEDURE." JURNAL ANALIS LABORATORIUM MEDIK 8, no. 2 (December 19, 2023): 94–100. http://dx.doi.org/10.51544/jalm.v8i2.4509.

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The success of PRP therapy in repairing tissue damage is influenced by the PRP preparation procedure. Currently, there’s no standardization of PRP preparation procedures, and various techniques are used, such as the use of anticoagulants and different centrifugation speeds. This study aimed to evaluating the PRP preparation procedures based on the centrifugations steps (single and double centrifugation) and the use of anticoagulants variation (sodium citrate, EDTA and ACD-A). This study was an experimental study and used blood samples from respondents. The selected respondents must meet inclusion and exclusion criteria. The treatment groups in this study were the single centrifugation group and the double centrifugation group. Each group will be divided into 3 subgroups with different anticoagulant usage (sodium citrate, EDTA and ACD-A). Statistical analysis results showed a significant difference in the mean platelet count in the sodium citrate , EDTA, ACD-A groups with single and double centrifugation steps. Evaluation of platelet preparation procedures in this study, a higher platelet count was obtained, specifically in the sodium citrate group (494 x 103 cells/µL), EDTA group (829.4 x 103 cells/µL), and ACD-A group (607.1 x 103 cells/µL), compared to single centrifugation in the sodium citrate group (354.8 x 103 cells/µL), EDTA group (408.1 x 103 cells/µL), and ACD-A group (390.6 x 103 cells/µL). The highest platelet count in PRP was achieved with the preparation procedure using EDTA as the anticoagulant with double centrifugation. Further research is necessary to evaluate PRP preparation procedures regarding the concentration of growth factors present in PRP.
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Janky, Kristen L., and Neil T. Shepard. "Unilateral Centrifugation." Otology & Neurotology 32, no. 1 (January 2011): 116–21. http://dx.doi.org/10.1097/mao.0b013e3181ff7549.

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Knight, Pamela. "Continuous Centrifugation." Nature Biotechnology 6, no. 11 (November 1988): 1344–45. http://dx.doi.org/10.1038/nbt1188-1344.

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Kim, Mu-Young, and Hyun-Jung Han. "Optimization of a Two-Step Centrifugation Protocol for Bovine Platelet-Rich Plasma." Acta Veterinaria 72, no. 3 (September 1, 2022): 375–87. http://dx.doi.org/10.2478/acve-2022-0030.

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Abstract Platelet-rich plasma ( PRP), an autologous platelet concentrated in plasma, is a source of diverse growth factors and is extensively utilized to promote tissue healing. Most of the clinical and laboratory investigations in veterinary medicine have focused on horses and dogs. Consequently, the types and detailed conditions of the PRP preparation method are based on those species. However, in bovine medicine, only a few studies have investigated the species-specific characteristics of bovine platelets. The aim of this study was to optimize the conditions of a two-step centrifugation method for bovine PRP. Whole blood samples were obtained from eight healthy lactating Holstein-Friesian cows. Eight running conditions for the first and second centrifugations each were evaluated based on the platelet recovery rate, the concentration of growth factors, and the adenosine diphosphate (ADP)-induced aggregation response, which reflects the premature platelet activation caused by the centrifugation process. The results of this study showed that for the first and second centrifugations, 900×g for 10 minutes and 1250×g for 15 minutes, respectively, were the most suitable conditions for the platelet recovery rate, and the concentration of growth factors was highest under these conditions without significant activation of premature platelet aggregation. Thus, we established an optimal two-step centrifugation protocol for bovine PRP that should provide a better understanding of bovine platelets.
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Xu, Shujing, and Ali Nadim. "Oscillatory counter-centrifugation." Physics of Fluids 28, no. 2 (February 2016): 021302. http://dx.doi.org/10.1063/1.4939988.

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PITTS, JIM E. "Crystallization by centrifugation." Nature 355, no. 6356 (January 1992): 117. http://dx.doi.org/10.1038/355117a0.

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ABAD-ZAPATERO, CELE. "Crystallization by centrifugation." Nature 356, no. 6368 (April 1992): 392. http://dx.doi.org/10.1038/356392b0.

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Dissertations / Theses on the topic "Centrifugation"

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Astorsdotter, Jennifer. "Dewatering Cellulose Nanofibril Suspensions through Centrifugation." Thesis, KTH, Skolan för kemivetenskap (CHE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215079.

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Cellulose nanofibrils (CNF) is a renewable material with unique strength properties. A difficulty in CNF production is that CNF suspensions contain large amounts of water. If CNF suspension volume can be decreased by dewatering facilitated by centrifugation, then transportation costs and storage costs can be reduced. The aim of this thesis is to investigate the impact various parameters have on CNF centrifugation dewatering and identify optimal conditions for maximal water removal. A laboratory study was conducted using four materials; 2.0 w% enzymatically treated CNF (CNF1), 1.9 w% carboxymethylated CNF (CNF2) and two commercial samples (1.9 w% CNFA and 1.8 w% CNFB). The main method was analytical centrifugation up to 2330 g. Parameters tested were initial concentration before centrifugation, temperature, NaCl addition, pH, and applied solid compressive pressure (g-force and surface weight). In addition to centrifugation experiments the four materials were characterized with laser diffraction, UV-vis absorption, Dynamic light scattering, and dry weight measurements. Analysis of the experimental data collected show that increase in initial concentration give a higher final concentration, but less water is removed. Furthermore, temperature changes have no effect on separation of CNF and water. At an applied solid compressive pressure of 3 kPa and initial concentration at 1.5 w% the concentrations 5.5 w%, 1.5 w%, 4.0 w%, and 4.3 w% can be reach for CNF1, CNF2, CNFA, and CNFB respectively. After extrapolation of polynomial functions fitted to experimental data an applied solid compressive pressure of 22 kPa and initial concentration at 1:5 w%, the concentrations 9.1 w%, 1.5 w%, 6.9 w%, and 7.9 w% are predicted for CNF1, CNF2, CNFA, and CNFB respectively. The thickening of CNF suspensions achieved and predicted in this thesis implies possibilities for large amounts of water removal, e.g. the water content in a CNF1 suspension is reduced from 65.7 litres/kg CNF to 10.0 litres/kg CNF at the solid compressive pressure 22 kPa. The concentrations at 22 kPa are determined by extrapolation from experimental data <3 kPa solid compressive pressure. The carboxymethylated CNF2 can not be dewatered unless it is diluted or if salt or pH is adjusted. This is directly correlated to the electrostatic forces in the suspension and the Debye length. Addition of salt or lowered pH also eliminate any concentration gradients in diluted and centrifuged CNF2 suspensions.
Cellulosa nanofibriller (CNF) är ett förnybart material med unika styrkeegenskaper. En svårighet med produktion av CNF är att CNF suspensioner innehåller stora mängder vatten. Om volymerna av CNF suspensioner kan minskas med avvattning genom centrifugering, då kan transport- och lagerkostnader sänkas. Målet med det här examensarbetet är att undersöka vilken inverkan olika parametrar har på CNF-avvattning genom centrifugering och identifiera optimala förhållanden för maximalt avlägsnande av vatten. En laboratoriestudie utfördes på fyra olika material. De fyra materialen är 2 w% enzymatiskt behandlad CNF (CNF1), 1.9 w% karboxymetylerad CNF (CNF2) och två kommersiella prover (1.9 w% CNFA och 1.8 w% CNFB). Den huvudsakliga metoden var analytisk centrifugering upp till maximalt 2330 g. De testade parametrarna var initial koncentration innan centrifugering, temperatur, NaCl tillsats, pH, och applicerat fast kompressionstryck (g-kraft och ytvikt). Förutom centrifugeringsexperimenten så karaktäriserades the fyra mmaterialen med laser diffraktion, UV-vis absorption, dynamisk ljusspridning och vägningar av torrhalt. Analys av den experimentella data som insamlats visar att en ökad initial koncentration ger en högre slutkoncnentration, men mindre vatten kan bortföras. Temperaturförändringar har ingen effekt på separation av CNF och vatten. Vid ett applicerat fast kompressibelt tryck på 3 kPa och en initial koncentration 1.5 w% kan koncentrationerna 5.5 w%, 1.5 w%, 4.0 w%, och 4.3 w% nås för CNF1, CNF2, CNFA, och CNFB. Efter extrapolering av polynoma funktioner passad till experimentell data förutspås att koncentrationerna 9.1 w%, 1.5 w%, 6.9 w%, och 7.9 w% kan nås för CNF1, CNF2, CNFA, and CNFB vid 22 kPa och en initial koncentration på 1.5 w%. Förtjockningen av CNF suspensioner som kan, eller förutspås kunna nås genom centrifugering i det här examensarbetet innebär att det är möjligt att avlägsna stora mängder vatten, till exempel kan vatteninnehållet i CNF1 minskas från 65.7 liter/kg CNF till 10.0 liter/kg CNF vid 22 kPa fast kompressionstryck. Koncentrationerna vid 22 kPa fast kompressionstryck är extrapolerade från exprimentell data <3 kPa fast kompressionstryck. Den karboy- metylerade CNF2 kan inte avvattnas om den inte späds ut eller om salt eller pH justeras. Detta är direkt kopplat till de elektrostatiska krafterna i suspensionen och Debye längden. Tillsats av salt eller sänkt pH eliminerar också de koncentrationsgradienter som kan förekomma i utspädda centrifugerade CNF2 suspensioner.
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Keles, Serhat. "Fine Coal Dewatering Using Hyperbaric Centrifugation." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37807.

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The solid-solid separation processes employed by modern coal preparation plants require large amounts of process water that must be removed from the surfaces of particles using mechanical dewatering equipment. Unfortunately, the existing processes that are used to dewater fine particles are inefficient in terms of moisture reduction and/or solids recovery. Many coal preparation plants are forced to discard fine coal particles because of the inability of existing technologies to reduce the moisture content of this product to an acceptable level. In light of this problem, a new ultrafine dewatering process called hyperbaric filter centrifugation (HFC) has been developed. This novel method combines centrifugation and pressure filtration within a single process to substantially reduce moistures over what can be achieved using conventional dewatering systems. In the current study, steady-state and dynamic dewatering models were developed in order to be able to simulate the behavior of the HFC technology. The steady-state model, which was based on grain-size properties, used empirical expressions to predict product moistures. On the other hand, the dynamic model was based on fundamental theories of filtration and centrifugation. Although the dynamic model provided a better understanding of the working principles of the process, the steady-state grain model produced more accurate equilibrium moisture predictions. Therefore, the steady-state model was used to further investigate the effects of several parameters on cake moistures. As such, the steady-state model was useful for scale up and design purposes. The steady-state dewatering model was also used to perform an economical analysis of potential applications of the HFC technology. The model was used to investigate a variety of new circuit designs that have the potential to be commercially applied in the coal industry. The results clearly showed that this new technology would allow coal companies to process difficult-to-dewater ultrafines using the HFC process, while coarser solids would be more appropriately dewatered using conventional technologies such as vacuum filters or screenbowl centrifuges. This â split dewateringâ concept would provide substantially higher profitability due to lower moistures and higher recoveries of ultrafine solids than could be achieved using a single dewatering process. Laboratory- and pilot-scale versions of this technology has been constructed and tested at the facilities of Mining & Minerals Engineering Department of Virginia Tech. Results of this testing program showed that 30-50% lower moisture values than the ones obtained using conventional mechanical dewatering processes could be achieved with the HFC technology. Based on these promising results, a pilot-scale prototype unit, which was tested successfully at several commercial U.S. coal plants, was also constructed by Decanter Machine, Inc. Finally, the process of developing of this novel technology was successfully completed with the sale of the first full-scale commercial unit by Decanter Machine, Inc. to a major U.S. coal producer.
Ph. D.
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Chen, Fei Ph D. Massachusetts Institute of Technology. "Magnetically enhanced centrifugation for continuous biopharmaceutical processing." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51565.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.
Includes bibliographical references.
Effective separation and purification of biopharmaceutical products from the media in which they are produced continues to be a challenging task. Such processes usually involve multiple steps and the overall product loss can be significant. As an integrative technique, high gradient magnetic separation (HGMS), together with the application of functional magnetic particles, provides many advantages over traditional techniques. However, HGMS has a number of drawbacks; and its application is limited because it is inherently a batch process and it is difficult to recycle the magnetic nanoparticles. This thesis explores the development of a new type of continuous magnetic separation process, called magnetically enhanced centrifugation (MEC), which exploits the interactions of magnetic particles with magnetic field gradients, forced convective flows and large centrifugal forces. Magnetically susceptible wires in a uniform magnetic field facilitate the capture and aggregation of magnetic particles on wires, and a centrifugal force perpendicular to the magnetic force conveys the particle sludge parallel to the wires in a continuous mode. The primary focus of this thesis is multi-scale modeling and simulation to understand the underlying physics of MEC processes. The potential of MEC as an effective unit operation for biopharmaceutical downstream processing has been demonstrated. Unlike traditional batch-mode HGMS, MEC has a great advantage in that it can be operated continuously as magnetic particles captured on wire surface are constantly removed.
(cont.) A dimensionless model for simulating the trajectories of magnetic particles in combined magnetic and flow fields has been developed. The model was first applied to single wire configurations and then extended to multi-wire arrays. It was shown that modified rhombic arrays can provide high capture efficiency while maintaining low pressure drop. It is also shown that capture efficiencies based on results for clean, particle-free wires, may be seriously in error because the particle buildup that accumulates on the wire significantly distorts the flow and the magnetic fields and thus influences the particle trajectories. The dynamic buildup growth process was treated as a moving-boundary problem. Simulation results have shown that the capture efficiency decreases dramatically as particle buildup volume increases. In addition, the influence of particle chaining under magnetic dipole-dipole forces on separation efficiency has been investigated. Magnetic particles form chains as soon as they enter a background magnetic field, and are captured in the form of particle chains. The hydrodynamic force on particle chains was calculated using a 3-D CFD simulation. The capture radius calculated with considering the chaining effect is few times as great as the capture radius calculated assuming individual particles. Bench-top MEC experiments have shown that magnetic particle buildup generally comprises two layers with distinct structures: a spiky layer with all chains parallel to the magnetic field, and a densely-packed layer near the wire.
(cont.) This unique structure reflects the dominance of magnetic forces near the wire and of magnetic dipole-dipole interactions at locations further from the wire. As more and more particles accumulate on the wire surface, the centrifugal force can overcome the cohesion of the layer or the adhesion of the layer to the wire, leading to movement of the buildup material. The onset of such movement can be achieved either by increasing the centrifugal force or by increasing the buildup height. Energy and force analyses have been carried out to study various scenarios of buildup movement. For monodisperse magnetic particles, four scenarios can be expected: chain-like layer collapsing down (I), rigid body movement (II), buildup breakage (III), and mixed behavior of rigid body movement and buildup breakage (IV). A set of design formulas were derived to predict buildup structure and different scenarios. Useful scenario and operating regime diagrams were obtained. A discrete element modeling (DEM) package was developed to study the dynamics and rheological behavior of highly concentrated magnetic particle systems. For monodisperse magnetic particles, simulation results confirmed the four regions of the scenario diagram as predicted by force arguments. For polydisperse magnetic particles, DEM simulations showed that the buildup exhibits solid-like behavior when centrifugal effects are small, and liquid-like behavior with a continuous velocity profile when centrifugal effects are large.
(cont.) DEM simulations were able to predict the three dimensional effects, including the buildup profiles at the wire tip. Taken together, the results of this work provide a general strategy that can be used as a starting point for the design, evaluation, and optimization of magnetically enhanced processes that are suitable for biopharmaceutical downstream processing.
by Fei Chen.
Ph.D.
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Duda, Kevin R. 1979. "Squat exercise biomechanics during short-radius centrifugation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38525.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Vita.
Includes bibliographical references (p. 178-187).
Artificial gravity (AG) created by short-radius centrifugation is a promising countermeasure to the physiological de-conditioning that results from long-duration spaceflight. However, as on Earth, gravity alone does not ensure fitness. We will need to supplement passive exposure to AG with physical exercise to achieve a comprehensive countermeasure. Before AG exercise can be deemed safe and effective, we must understand how Coriolis accelerations and a gravity gradient affect our biomechanics and how centrifuge-based exercises differ from Earth-upright ones. Two experiments were designed to investigate the squat biomechanics while upright in the laboratory and while lying supine on a horizontal, clockwise-rotating short-radius centrifuge at speeds up to 30 revolutions per minute. Constant force springs provided additional resistive force up to 25% of body weight. Dependent measure included the three-dimensional position of the left and right knee, left and right foot reaction forces, and muscle activity. We investigated the Coriolis-induced mediolateral knee perturbations and the sensory-motor after-effects from a multiple repetition protocol. The upright and centrifuge biomechanics were compared for similarities and differences between them. In addition, a two-dimensional kinematic model was developed to predict foot reaction forces, Coriolis accelerations, and joint torques.
(cont.) Our results show that mediolateral knee travel during the AG squats was 1.0 to 2.0 centimeters greater than Earth-upright squats. Increasing the rotation rate or adding resistive force did not affect the results. The peak foot forces increased with rotation rate, but rarely exceeded 200% body weight. The ratio of left-to-right foot force during centrifugation was non-constant and approximately sinusoidal, suggesting a postural correction for the Coriolis accelerations. There was a qualitative difference in the foot force vs. knee angle profile between upright and centrifuge-supine because of the centripetal acceleration. Muscle activity, however, was qualitatively similar between the conditions. The kinematic model was used to evaluate the exercise safety and extend the results to larger-radius centrifuges. We conclude that centrifugation provides a unique and challenging environment for exercise and that a brief artificial gravity squat can be carried out safely. The results are extended to cycle ergometry, when possible, and recommendations are made for future AG squat protocols. Supported by NASA Grant NNJ04HD64G and the MIT-Italy Program Progetto Roberto Rocca.
by Kevin Ronald Duda.
Ph.D.
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Stuhtmann, Gesa [Verfasser]. "Density gradient centrifugation of stallion semen / Gesa Stuhtmann." Hannover : Bibliothek der Tierärztlichen Hochschule Hannover, 2011. http://d-nb.info/1019427086/34.

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Pouly, Jeremie M. "A parametric study of vestibular stimulation during centrifugation." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35291.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"February 2006."
Includes bibliographical references (p. 155-160).
Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure to the health problems associated with long duration human spaceflight. Head-turns performed during centrifugation, however, trigger a disturbing vestibular response that is only qualitatively understood. In order to design an efficient incremental adaptation procedure, the present study investigates the quantitative aspect of the vestibular side effects associated with AG, in particular, the relationship among crosscoupled stimulation, vestibular response, and adaptation. We tested 20 young adults with supine right-quadrant yaw head-turns performed in a dark environment during short-radius centrifugation. We studied the changes in vestibular response and adaptation to head-turns at different levels of cross-coupled stimulation. Nine combinations of head-turn angle (20°, 40° or 80°) with centrifugevelocity (12, 19 or 30 rpm) were tested over two consecutive days.
(cont.) There were four key findings: 1. All measures, except the slow-phase velocity (SPV) peak amplitude of the vestibulo-ocular reflex, decrease significantly between the two experimental days, which demonstrates that significant adaptation is achieved. 2. Large head-angles lead to longer vertical vestibulo-ocular reflex time-constants than smaller angles do, but do not lead to greater adaptation. 3. In the nose-up position, the perceived body-tilt is highly correlated with the true tilt of the gravito-inertial force at mid-chest level. 4. The SPV-peak amplitude and all subjective ratings except body-tilt show significant correlation with the intensity of the cross-coupled stimulus (CCS): the larger the CCS, the stronger the vestibular response.
by Jeremie M. Pouly.
S.M.
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Bagur, Eric. "Les mélanges nutritifs injectables : étude granulométrique par centrifugation." Bordeaux 2, 1995. http://www.theses.fr/1995BOR2P078.

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Garrick-Bethell, Ian 1980. "Cross plane transfer of vestibular adaptation to human centrifugation." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17770.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.
Includes bibliographical references (p. 101-106).
Human short-radius centrifugation (SRC) is being investigated as a volume-efficient means of delivering intermittent doses of "artificial gravity" to counter the deleterious effects of long exposures to weightlessness. Rotation rates on short radius centrifuges are high to provide the needed g-loading, and therefore entail a variety of unusual vestibular stimuli when certain head movements are made. Since these movements can elicit inappropriate nystagmus, illusions of tumbling, and motion sickness, efforts have been made to adapt people to the stimuli. So far these efforts have been successful in showing that people will adapt to at least one plane of head motion, the yaw (transverse) plane, during supine head-on-axis rotation. However, astronauts must be adapted to all planes of head motion if they are to function normally on the centrifuge. If adaptation to yaw head turns transferred to some extent to pitch (sagittal) plane turns, or any other plane of motion, it would greatly simplify and hasten the adaptation process. To investigate if transfer of adaptation across planes is possible, 10 subjects in the Experimental Group performed a sufficient number of yaw plane head turns to demonstrate adaptation. Adaptation was indicated by decreases in metrics of the off-axis vestibuloocular reflex induced by the head turns, and by subjective ratings of illusory motion. A block of pitch movements was performed before and after the yaw movements, and these two pitch blocks were compared to assess how much adaptation to pitch head turns had taken place. The same procedure was followed on a subsequent day. A Control Group of 10 subjects performed only the blocks of pitch turns, and their adaptation was compared to the adaptation to pitch turns measured in the Experimental
(cont.) Group. While both Control and Experimental Groups showed statistically significant signs of adaptation to pitch head turns, we failed to find any significant differences between the amounts of adaptation. If true, this result implies that adaptation to SRC may need to be performed one plane of motion at a time. Additionally, it implies that the brain and vestibular system does not build up a generalized model of SRC stimulation, but rather builds adaptation one input at a time.
by Ian Garrick-Bethell.
S.M.
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Bruni, Sylvain 1981. "Artificial gravity : neurovestibular adaptation to incremental exposure to centrifugation." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/26749.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 115-122).
(cont.) not build up adaptation, all subjects in the experimental group who completed the protocol showed signs of adaptation to the stimulus. Only one subject did not complete the five sessions, setting the drop-out rate at about 14%. If this conclusion holds true with more subjects, then a better protocol of adaptation has been unveiled.
In order to counteract the debilitating effects of the space environment on the human body, short-radius intermittent centrifugation is investigated as a possible means to expose astronauts to artificial gravity. Whereas AG is efficient in providing stimuli for muscles, bones and cardiovascular system, short-radius centrifugation elicits discomfort and illusory sensations of motion if particular head movements are made while spinning. Past research has shown that human beings can adapt to these sensations and undergo various stimuli without the disturbing effects of motion sickness, sensations of tumbling and inappropriate eye movements. However, current protocols for adaptation basically consist in repeated exposure to the discomfort. This solution is not satisfactory because the drop-out rate oscillates between 30 and 50%. Since it is not acceptable to spend days of training on astronauts who, in the end, because of this training, could become unsuitable for flight, it is of primary importance to find a training protocol that achieves adaptation without going through permanent discomfort. Incremental exposure to centrifugation is expected to be a compromised protocol to bring trainees to adaptive level without exposing them to maximum discomfort. Seven subjects were exposed to centrifugation during a five-day protocol, over which the speed of rotation was progressively increased. As in previous protocols of adaptation, subjects performed provocative head movements at all speeds. A control experiment had ten subjects exposed to centrifugation without making head turns, in order to verify to what extent the experimental conditions of measurement impact the subjects' behavior and reactions. While subjects in the control experiment did
by Sylvain Bruni.
S.M.
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Edmonds, Jessica Leigh. "Exercise protocols during short-radius centrifugation for artificial gravity." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45273.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.
"June 2008."
Includes bibliographical references (p. 125-133).
Long-duration spaceflight results in severe physiological deconditioning, threatening the success of interplanetary travel. Exercise combined with artificial gravity provided by centrifugation may be the comprehensive countermeasure needed to prevent such deconditioning. The aims of this study were (1) to characterize the physiological responses to longitudinal g-gradient and high g-levels during short-radius centrifugation, and (2) to quantify the fitness benefits of an eight-week exercise program on a short-radius centrifuge. In the first experiment, we utilized a tilting short-radius centrifuge to investigate heart rate, blood pressure, and calf volume responses to high g-level and g-gradient centrifugation with and without light exercise (stepping in place). All measures increased significantly with increasing g-level and increasing g-gradient, but these effects were reduced significantly when the subject stepped in place. In the second experiment, we quantified the effectiveness of an eight-week exercise program using a stair-stepper and resistive arm bands on a horizontally-rotating short radius centrifuge. Healthy, previously sedentary subjects exercised at a constant heart rate three times per week for eight weeks, and underwent measurements to test aerobic capacity and endurance, strength, and body composition at weeks 0, 4, and 8. Eight subjects successfully completed 24 exercise sessions with little or no discomfort. After eight weeks of exercise, we found significant improvements in aerobic capacity (increased work rate for a given heart rate, increased stepping endurance), muscular strength (increased number of push-ups), and body composition (decreased leg fat percentage, increased pelvic bone mineral content).
(cont.) Stepping in place significantly reduced the physiological responses to increasing g-level and g-gradient, suggesting that subjects may be able to better tolerate exposure to high-g centrifugation if they exercise. Further, an eight-week exercise program using a stair-stepper on a short-radius centrifuge resulted in improvements to aerobic capacity, strength, and body composition. These two studies demonstrate the feasibility and benefits of exercise in an artificial gravity environment.
by Jessica Leigh Edmonds.
Ph.D.
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Books on the topic "Centrifugation"

1

Regel, Liya L., and William R. Wilcox, eds. Processing by Centrifugation. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0687-4.

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Leung, Wallace Woon-Fong. Industrial centrifugation technology. New York: McGraw-Hill, 1998.

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Regel, Liya L. Processing by Centrifugation. Boston, MA: Springer US, 2002.

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Rickwood, D. Centrifugation: Essential data. Chichester, West Sussex: Wiley, 1994.

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1943-, Graham J. M., ed. An introduction to centrifugation. Oxford: Bios, 1991.

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D, Rickwood, ed. Preparative centrifugation: A practical approach. Oxford: IRL Press at Oxford University Press, 1992.

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Forster, R. M. The application of density gradient centrifugation to palynology. [Hull], England: School of Geography & Earth Resources, University of Hull, 1989.

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K, Brownfield Isabelle, and Geological Survey (U.S.), eds. Improved density gradient separation techniques using sodium polytungstate and a comparison to the use of other heavy liquids. [Denver, Colo.]: U.S. Dept. of the Interior, U.S. Geological Survey, 1993.

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K, Brownfield Isabelle, and Geological Survey (U.S.), eds. Improved density gradient separation techniques using sodium polytungstate and a comparison to the use of other heavy liquids. [Denver, Colo.]: U.S. Dept. of the Interior, U.S. Geological Survey, 1993.

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Ungarish, M. Hydrodynamics of suspensions: Fundamentals of centrifugal and gravity separation. Berlin: Springer-Verlag, 1993.

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Book chapters on the topic "Centrifugation"

1

Gooch, Jan W. "Centrifugation." In Encyclopedic Dictionary of Polymers, 130. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_2154.

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Buxbaum, Engelbert. "Centrifugation." In Biophysical Chemistry of Proteins, 237–49. Boston, MA: Springer US, 2010. http://dx.doi.org/10.1007/978-1-4419-7251-4_25.

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Pomeranz, Yeshajahu, and Clifton E. Meloan. "Centrifugation." In Food Analysis, 409–18. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-6998-5_25.

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Isenberg, Gerhard. "Centrifugation." In Cytoskeleton Proteins, 20–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79632-6_6.

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Basha, Mahin. "Centrifugation." In Springer Protocols Handbooks, 13–21. New York, NY: Springer US, 2019. http://dx.doi.org/10.1007/978-1-0716-0134-1_3.

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Hu, Xing, and Peng Zhang. "Centrifugation." In Bioprocess Engineering, 15–25. Boca Raton, FL : Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9780429466731-2.

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Gandhi, Kamal, Neelima Sharma, Priyae Brath Gautam, Rajan Sharma, Bimlesh Mann, and Vanita Pandey. "Centrifugation." In Springer Protocols Handbooks, 85–102. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1940-7_3.

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Khasim, S. M., K. Thammasiri, S. Rama Rao, and M. Rahamtulla. "Centrifugation." In Plant Techniques, 99–106. London: CRC Press, 2024. http://dx.doi.org/10.1201/9781003503682-7.

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Devi, Rooma, Aman Chauhan, Simmi Kharb, and Chandra Shekhar Pundir. "Centrifugation." In Clinical Biochemistry, 269–73. New York: Jenny Stanford Publishing, 2023. http://dx.doi.org/10.1201/9781003455660-26.

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Regel, Liya L., William R. Wilcox, Ramnath Derebail, and Peter V. Skudarnov. "Vibration During Centrifugation." In Processing by Centrifugation, 1–6. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-0687-4_1.

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Conference papers on the topic "Centrifugation"

1

Denfors, I., H. Wadenvik, and J. Kutti. "PREPARATION OF A REPRESENTATIVE PLATELET POPULATION BY A SINGLE STEP SLOW CENTRIFUGATION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644549.

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Circulating platelets differ with respect to size, density and functional ability. In several experimental settings it is of vital importance that a representative platelet-rich plasma (PRP) is extracted from the anticoagulated blood. We therefore investigated the effect of centrifugation time and gravitational force on platelet yield and platelet volume distribution in PRP obtained by a single step slow centrifugation.Methods. From each of 12 healthy male blood donors, 357 ml of venous blood were mixed with 63 ml citrate phosphate dextrose in a plastic bag. 20 ml aliquots of the anticoagulated blood were transferred into 30 ml screwcap polycarbonate tubes (Nalgene Labware). PRP was prepared by a single step slow centrifugation in a microprocessor-controlled bench centrifuge (Hettich Rotanta/RP). The gravitational force was calculated at the bottom of the tube. Centrifugations were performed at 180, 200, 220, 240, 260 g for 10 min, at 180, 200, 220, 240, 260 g for 15 min and at 120, 140, 160, 180, 200 g for 20 min. Three hours after blood collection, the platelet count, mean platelet volume (MPV) and platelet distribution width were determined in PRP and anticoagulated blood with an impedance cell counter (Coulter Counter Model S-Plus VI). Student's t-test was employed for comparison of mean values.Comments. Very precise centrifugation conditions can be provided by using a microprocessor-controlled centrifuge and a "fully representative" platelet population can be isolated with a single step slow centrifugation method.
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Haibo Yu, Wen J. Li, Yanli Qu, Xiaojun Tian, Zaili Dong, Yuechao Wang, Ke Qin, and Wencai Ren. "Purification of SWNTs using high-speed centrifugation." In 2008 3rd IEEE International Conference on Nano/Micro Engineered and Molecular Systems. IEEE, 2008. http://dx.doi.org/10.1109/nems.2008.4484390.

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"Characterising mineral slurry dewatering through laboratory centrifugation." In 20th International Congress on Modelling and Simulation (MODSIM2013). Modelling and Simulation Society of Australia and New Zealand, 2013. http://dx.doi.org/10.36334/modsim.2013.a11.berres.

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Arias, Fernando, Micah Hester, Nathan Long, Abraham Diaz, Aylin Mona, Ben Casillas, Bethany Hansen, et al. "Mars Artificial Gravity Habitat with Centrifugation (MAGICIAN)." In 2024 IEEE Aerospace Conference. IEEE, 2024. http://dx.doi.org/10.1109/aero58975.2024.10521126.

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Mailyan, Levon, Sergei Stel'makh, Evgenii Shcherban’, and Vladislav Smachney. "Physical bases of variatropy regulation and control of concrete properties by technological factors during centrifugation and vibro-centrifugation." In PROCEEDINGS OF THE II INTERNATIONAL SCIENTIFIC CONFERENCE ON ADVANCES IN SCIENCE, ENGINEERING AND DIGITAL EDUCATION: (ASEDU-II 2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0104561.

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Laughner, J. W., F. J. Calnan, B. Borglum, and L. M. Falter. "Centrifugation and Fast Firing of a Commercial BaTiO3Powder." In Sixth IEEE International Symposium on Applications of Ferroelectrics. IEEE, 1986. http://dx.doi.org/10.1109/isaf.1986.201162.

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Juiz, Vitor Moura, Matheus Alex Domit Mallat, Shanely da Silva Ribeiro, Gabriella Maria Silveira de Sá, Hudson Jean Bianquini Couto, and Eduardo de Sousa Lima. "Classification of Nanometric Silicon Carbide Powder by Centrifugation." In Anais do Encontro Nacional de Modelagem Computacional e Encontro de Ciência e Tecnologia dos Materiais. Recife, Brasil: Even3, 2023. http://dx.doi.org/10.29327/1340957.26-34.

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Wei, Junhua, and Jenny Qiu. "Tunable Optical Properties of Graphene Quantum Dots by Centrifugation." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64756.

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In this work, tunable optical properties of graphene quantum dots (GQDs) were achieved by centrifugation method. GQDs prepared through intercalating and exfoliating commercially available stacked graphene nanofibers were separated into two samples with different mean sizes by centrifugation. The separated GQD samples were characterized by transmission electron microscope (TEM). The optical properties of the GQD samples were measured by UV-visible and photoluminescence spectroscopy. The characterization results demonstrated that the UV and photoluminescence of GQDs were highly correlated with their sizes and surface chemistry. As the diameters of GQDs reduced, the UV peaks of the GQD blue shift, and the photoluminescence of PL red shift, indicating that the centrifugation method can be used to efficiently achieve tunable optical properties from as-synthesized GQD.
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Camassa, Roberto. "Convective instabilities in liquid centrifugation for nuclear wastes separation." In The international conference on accelerator-driven transmutation technologies and applications. AIP, 1995. http://dx.doi.org/10.1063/1.49056.

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Jianbao, Fu, Li Shunqun, and Chen Lihang. "Centrifugation method for reducing heavy metal content in sediment." In 2021 4th International Symposium on Traffic Transportation and Civil Architecture (ISTTCA). IEEE, 2021. http://dx.doi.org/10.1109/isttca53489.2021.9654727.

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Reports on the topic "Centrifugation"

1

Bowman, C. D. Liquid centrifugation for nuclear waste partitioning. Office of Scientific and Technical Information (OSTI), March 1992. http://dx.doi.org/10.2172/7023850.

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Bowman, C. D. Liquid centrifugation for nuclear waste partitioning. Office of Scientific and Technical Information (OSTI), March 1992. http://dx.doi.org/10.2172/10176356.

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Buerger, Raimund, and Kenneth H. Karlsen. A Strongly Degenerate Convection-Diffusion Problem Modeling Centrifugation of Flocculated Suspensions. Fort Belvoir, VA: Defense Technical Information Center, June 2000. http://dx.doi.org/10.21236/ada397140.

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Koenig, S. C., Craig Reister, J. Schtaub, Gary Muniz, and Tim Fergusan. Cardiac Pacing in a Chronically Instrumented Non-Human Primate Model during Centrifugation,. Fort Belvoir, VA: Defense Technical Information Center, September 1995. http://dx.doi.org/10.21236/ada300621.

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Tiller, F. M. Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing. Office of Scientific and Technical Information (OSTI), June 1992. http://dx.doi.org/10.2172/5105692.

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Johnson, M. E., A. R. Montoro Bustos, S. K. Hanna, E. J. Petersen, K. E. Murphy, L. L. Yu, B. C. Nelson, and M. R. Winchester. Sucrose density gradient centrifugation for efficient separation of engineered nanoparticles from a model organism, Caenorhabditis elegans. Gaithersburg, MD: National Institute of Standards and Technology, October 2017. http://dx.doi.org/10.6028/nist.sp.1200-24.

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Martinez, Melissa. Lab Basics: Mini Centrifuges. ConductScience, June 2022. http://dx.doi.org/10.55157/cs20220601.

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Mini centrifuges are compact benchtop centrifuges designed to meet the centrifugation needs of laboratories with limited space. Primarily used for quick spin-downs, they are particularly suitable for microfuge and PCR tubes. Operating on the principle of sedimentation, mini centrifuges separate molecular lab samples based on density. They find applications in various fields like environmental, chemical, molecular biology, and biomedical research, including mixing PCR master mix and microfiltration. Despite their advantages of space efficiency and ease of use, they are not well-suited for high-output labs due to their small to medium output yield.
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Tiller, F. M. Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing. Progress report, January 1993--November 1993. Office of Scientific and Technical Information (OSTI), November 1993. http://dx.doi.org/10.2172/10195065.

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Tiller, F. M. Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing. [Annual report], February 1, 1991--January 31, 1992. Office of Scientific and Technical Information (OSTI), June 1992. http://dx.doi.org/10.2172/10155848.

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Sagaiyaraj, Bernard. Increasing Energy Efficiency of Central Cooling Systems with Engineered Nanofluids. Department of the Built Environment, 2023. http://dx.doi.org/10.54337/aau538344493.

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Buildings consume about 40% of the world’s energy consumption and of that, 65% is dedicated to cooling (or heating) systems. Central building cooling uses water as the main heat transfer medium. The nanoparticle fluid suspension exhibits thermal properties superior to water. The goal was to achieve the highest possible thermal properties with just the right amount of nanoparticles in a uniform and stable dispersion and suspension in water. This engineered nanofluid contains a uniform and stable suspension of graphene nanoparticles (GNP) in water. Using covalent functionalization, centrifugation and high-speed dispersion, the GNP remains in a stable suspension indefinitely. The nanofluid is applied to the closed loop of the chilled water system, where the heat transfer enhancement occurs at the fluid tubes within the evaporator and the tubing in the chilled water coils within the Air Handling Units(AHUs). The Proof of Concept (POC) completed in 2019 using laboratory-derived nanofluid resulted in energy saving that averaged at 32% compared with the baseline fluid (water). In 2022, a Scaled-Up mini plant produced GNP nanofluids in a commercial process environment, showing an average energy savings of 21%. These results were further verified and validated on small chilled water plants outside of the Scaled-Up plant with 25% and 29% average savings.
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