Dissertations / Theses: 'Absorption'

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Morrow, Heather. "Shock absorption." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ54662.pdf.

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Eriksson, Patrik. "Akustikavskärmning och absorption." Thesis, Gotland University, Institutionen för humaniora och samhällsvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hgo:diva-547.

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Det här är ett projekt i industriell design som gick ut på att lösa ett problem. Projektet var ett samarbete med kontors- och utbildningsmöbelföretaget Abstracta. Problemet var att det på arbetsplatser idag lätt blir högljutt och bullrigt, speciellt i öppna kontorslösningar. För att ta fram en produkt som löser problemet gjordes undersökningar och analyser av marknaden, kunden, användaren, akustik och material. Det utgjorde grunden för en idégenerering som resulterade i ett koncept, som sedan vidareutvecklades till en serie akustikabsorbenter. Absorbenternas utseende speglar en ljudvågs avtagande och formpressas i en blandning av lin och hampa. Materialet ger produkterna en klar hållbarhetsaspekt, vilket var något eftersträvades. Produktserien passar in och kompletterar Abstractas sortiment.

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Webb, J. K. "QSO absorption lines." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234000.

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The absorption lines found in the spectra of distant quasars provide a unique method of probing the physical conditions in the universe at early epochs. This thesis describes a study of the Lyman alpha forest absorption systems seen in the spectra of high redshift QSOs. The Anglo-Australian Telescope has been used to obtain high resolution spectra of several bright QSOs. Considerable effort has gone into developing statistical techniques for profile fitting to the data to objectively and reliably extract the parameters associated with each absorbing cloud. The distribution functions for these are given and discussed. Particular attention has been paid to the clustering properties of the Lyman alpha clouds and it is found that they are weakly (but significantly) clustered on small velocity scales. Possible interpretations of this result are discussed. One especially interesting aspect of QSO absorption systems concerns the potential for measuring, or obtaining limits on, the deuterium to hydrogen abundance at high redshifts. A knowledge of this quantity is important for constraining cosmological models and can also help us to understand the chemical evolution of light elements in galaxies. A series of numerical simulations has been carried out to explore the potential for such measurements and an absorption system has been analysed to obtain an upper limit to D/H at z = 3.

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Outram, Philip James. "QSO absorption systems." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624575.

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5

Currie, John S. "Absorption heat recovery." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/13527.

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Industrial drying operations are highly energy intensive, usually utilising a primary energy source to provide the necessary heat for the production of a wide range of materials. The use of hot air as the heat and mass transfer medium leads to a resultant loss of energy through the venting of humid exhaust streams. An absorption heat transformer pilot plant was designed and constructed to investigate the potential of recovering this waste heat. Using a two stage cycle, simulated dryer exhaust streams were successfully dehumidified and reheated. The first stage of the transformer employed a direct contact process which used a concentrated absorbent solution, in this case aqueous lithium bromide solution, to reduce the humidity of the gas stream. This stage was followed by an indirect contact process using a novel absorption column to reheat the 'dry' gas. It was found that, based on initial water vapour partial pressures of around 0.2 bar, exit partial pressures as low as 0.04 bar were achievable. Temperature lifts of 50 - 70°C were possible in the reheat column, while the maximum exit gas temperature achieved was 160°C. In conjunction with the experimental studies, a computer simulation program was also written. Results of the model show that the absorption process was extremely rapid, occurring within the first 5 cm (6%) of the absorption column. A good comparison between the experimental and computer results was achieved. A preliminary design of an industrial heat transformer was also proposed following an industrial case study of a spray drying operation.

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6

Kaufman, Sarah K. "Moments of Absorption." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1133.

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Moments of Absorption explores the conceptual and visual themes that are presented in my MFA thesis exhibition. The research looks into the absorption of the nude subject, the gestures that communicate this absorption, and the domestic space as a stage for the presentation of these gestures. This work investigates a tension between the theatrical and the natural as represented by images.

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Kouneli, Athina. "CO2 absorption in power plants : Emphasizing on CO2 absorption in biphasic solvent." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21842.

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Carbon dioxide, the famous and vital to life gas, is also an important greenhouse gas. Since the combustion of fuels leads to the production of carbon dioxide it had to be expected that since the industrial revolution the concentration of carbon dioxide in the atmosphere was to be rapidly increased. When the consequences and the causes of the greenhouse effect were understood, serious efforts were made by the global community to reduce the greenhouse gases production and CO2 among them. The Kyoto Protocol, an international agreement linked to the United Nations Framework Convention on Climate Change, commits State Parties, also EU among them, to reduce the greenhouse gases by setting internationally binding emission reduction targets. The first commitment period started in 2008 and ended in 2012 and had as goal an average 5% reduction of carbon dioxide and other greenhouse gases, whereas during the second commitment period (2013-2020) the parties committed to reduce greenhouse gas emissions at least 18% below the 1990 levels. Greenhouse gas emissions in the EU-28 in 2013 stood at 4611 million tones of CO2 and the fuel combustion and the fugitive emissions were responsible for the 57.2% of the carbon dioxide production. The electricity, gas, steam and air conditioning supply activities account for the 26.6% of the emissions. Therefore it can be easily understood that the power plants is an important sector in CO2 production and therefore their carbon dioxide emissions need to be reduced. Carbon capture and storage (CCS) process is one of the available solutions to reduce the greenhouse gases. With CCS it is possible to capture the CO2 waste from large point sources and to transport it and deposit to a storage site, usually to a geological formation. This way the carbon dioxide can be prevented from getting released into the atmosphere. Within the framework of this thesis only the capture process of this method is to be examined. More specifically this thesis project involves research over a mature technology for CO2 capture, able to be adapted at plants exhaust gases. This technology is carbon dioxide absorption. The research on CO2 absorption today appears to focus mostly on power plants gases as the gases production of power plants are increased in comparison to other plants. It is indicated that using the classic solvents - amines for the CO2 absorption system results to a significant amount of energy consumption for the solvents regeneration. The purpose of this thesis is to search over the biphasic solvents as an alternative option to amines for the CO2 capture system and state the pros and cons mainly from the energy aspect. It is expected that the biphasic solvents contribute to energy reduction of the system as the solvents are separated into two phases after the absorption, giving the capability to remove the water phase from the absorption column and as a result use less energy in the regeneration column.

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Wright, Cody LeForge. "Evaluation of Absorption and Post-Absorptive Metabolism of Inorganic and Organic Zinc Sources." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010302-152709.

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A series of experiments was conducted to examine the absorption and post-absorptive metabolism of zinc (Zn) from inorganic and organic sources. Results of an in vivo experiment, using Holstein bull calves as models, suggested that, when Zn was supplemented at 20 mg Zn/kg DM for 98 d, Zn source had minimal impact on plasma or tissue Zn concentrations. However, when Zn was supplemented at 500 mg Zn/kg DM for 12 d, plasma and tissue Zn concentrations were greater in bulls that received Zn proteinate (ZnProt) than in those that received ZnSO and Ca only, uptake and transport of Zn from inorganic and organic Zn sources were similar. However, when added at high concentration in the presence of dietary antagonists, Zn uptake from organic sources appeared to be greater than from inorganic sources. Further research is certainly warranted to more clearly define differences in Zn absorption that may exist between inorganic and organic Zn sources at different dietary levels.

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Bohn, Torsten. "Magnesium absorption in humans /." [S.l.] : [s.n.], 2003. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14930.

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Wirth, Adrian. "Attosecond transient absorption spectroscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-140120.

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Alalwan, Tariq Abdulkarim Ebrahim. "Absorption of Dietary Flavonoids." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491922.

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Flavonoids represent a major class of plant polyphenols that are distributed ubiquitously in the human diet. Interest in the possible health-promoting effects of flavonoids has increased due to their various bioactive properties, as demonstrated in several in vitro and in vivo studies. Knowledge about flavonoid absorption and bioavailability is essential in order to fully understand their potential health benefits. This thesis was concerned with the uptake and absorption of dietary flavonoids in humans, with an emphasis on the effect of the chemical form of the flavonoid (as a product of processing) and the effect of food matrix. The first study investigated the flavonol content in different varieties of commerciallygrown tomatoes and widely consumed tomato-based food products. It was shown that the levels of rutin varied considerably between different cultivars and food-based products, with the highest levels found in cherry tomatoes. Furthermore, cellulase -Blf h-=-y_d_ro---'l~~is_of rut~~_:v.~~_ shown to be a viable alternative for the release ~f queLc~~~~__ aglycone. The second study was aimed to investigate the absorption and bioavailability of dietary quercetin glycosides and its aglycone from a food-based system (non-supplement) in humans by implementing urinary time-course analysis. Ingested quercetin glycosides resulted in an observed earlier appearance of quercetin conjugates in urine then when quercetin aglycone was ingested (1 h compared to 2 h). Significantly more quercetin was absorbed than the aglycone when present in a similar onion-based food matrix system (1.8% compared to 1.3%). Finally, a second human study was carried out to investigate the effect of dietary fat, 8.3% (w/w), on the bioavailability of quercetin present in onion-based foods as either quercetin glycosides or its aglycone. Absorption of quercetin in its glycosidic form was shown to be significantly higher than the aglycone form when co-ingested with fat (2.8% compared to 1.7%). The ingestion of quercetin with fat, compared with the study without fat, enhanced the bioavailability of quercetin glycosides and its aglycone by about 50 and 23%, respectively, which was significant for the quercetin glycoside meal only.

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L'Écuyer, Tristan Simon. "Water dimer atmospheric absorption." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq24864.pdf.

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13

Arita, Yoshihiko. "Multi-mode absorption spectroscopy." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489407.

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A novel approach to absorption spectroscopy is presented which achieves, simultaneously, wide spectral coverage and high spectral resolution. The principle of the technique - dubbed multi-mode absorption spectroscopy (MUMAS) - is described, and demonstrations of the principle are reported using two multi-mode sources: diode lasers and micro-cavity solid state lasers. The technique is shown to have potential for the detection of multiple species and multiple parameters using a single laser and a single detector.

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Jones, Arfon Lloyd. "Pulmonary absorption of insulin." Thesis, Cardiff University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327930.

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Ridout, G. "Percutaneous absorption of drugs." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373320.

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Wong, Choong Wah. "An absorption recompression system." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320018.

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Wilson, Kevin Earl. "Pion absorption on ³He." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36007.

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Rauch, Michael. "Lyman alpha absorption systems." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260453.

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Treffel, Pierre. "Absorption percutanee : nouvelles approches." Besançon, 1992. http://www.theses.fr/1992BESA3710.

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Transmontano, Raimundo João. "Oral absorption of dermatan sulfate /." [S.l.] : [s.n.], 1992. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9997.

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Kren, Christoph. "Flue gas fired absorption chillers." kostenfrei, 2008. https://mediatum2.ub.tum.de/node?id=965968.

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Radtke, Jörg. "Zufuhr und Absorption ausgewählter Flavonoide." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963446843.

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Sjöstrand, Filip, and Reza Yazdi. "Absorption of CO2 : - by Ammonia." Thesis, Växjö universitet, Institutionen för teknik och design, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-5256.

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In this diploma work, the absorption of CO2 in different liquid solutions was studied by gas absorption in a randomly packed column. To characterize the absorption a few experiments with SO2 absorption were made.The report has resulted due to the large amounts of carbon dioxide released into the atmosphere, mainly from fossil-fired power plants. To reduce these emissions, carbon dioxide can be separated from flue gas by different techniques such as CO2 absorption with ammonia. The work consists of a theoretical and a laboratory part of measurements and calculations. In the experimental part a system of absorption and associated test equipment was constructed. Different liquid solutions of pure water, potassium carbonate solution and ammonia in various concentrations were used to catch carbon dioxide by countercurrent absorption. Also SO2 was absorbed in the potassium carbonate solution to determine the gas film constant. The absorption efficiency of CO2 ranged from a few percent in the experiment with water to up to 7% with potassium carbonate solution. The CO2 absorption of ammonia varied with concentration and gave a separation of between 12 and 94%. Ammonia tests were made at both 10 and 20 °C. In general, a higher CO2-capture at 20 °C was obtained as confirmed by theory.
I detta examensarbete har absorptionseffektivitet av CO2 hos olika vätskelösningar undersökts genom gasabsorption i en slumpmässigt packad kolonn. För att karakterisera absorptionen absorberades även SO2 i några experiment. Rapporten är utförd med anledning av de stora mängder koldioxid som släpps ut i atmosfären, främst från fossileldade kraftverk. För att minska dessa utsläpp kan koldioxiden avskiljas från rökgaserna genom olika tekniker t.ex. genom CO2-absorption med ammoniak. Arbetet består av en teoridel och en laborativ del med mätningar och beräkningar. I den experimentella delen konstruerades ett system med en absorptionskolonn och tillhörande mätutrustning. Olika vätskelösningar bestående av rent vatten, kaliumkarbonatlösning och ammoniak i olika koncentrationer användes till att ta upp koldioxid genom motströms absorption. Även SO2 absorberades i kaliumkarbonatlösning för att bestämma gasfilmkonstanten. Absorptionsgraden av CO2 varierade från några få procent i försöket med vatten upp till 7 % med kaliumkarbonatlösningen. CO2-absorptionen av ammoniak varierade med koncentrationen och gav en avskiljning på mellan 12 och 94 %. Ammoniakförsöken gjordes med både vid 10 och 20 °C. Generellt erhölls en bättre CO2-avskiljning vid 20°C, vilket bekräftas av teorin.

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Motavas, Saloome. "Optical absorption in carbon nanotubes." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50121.

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Due to their unique optical properties, carbon nanotubes have been widely investigated for use in photonic and optoelectronic devices and optical absorption and emission with nanotubes have been achieved in experiments. On the other hand, the structural characteristics of nanotubes, e.g. the chirality, diameter, and length, as well as other factors such as the polarization of the incident light, presence of a magnetic field and mechanical deformation can significantly affect the optical properties of these structures. Some of these effects have been theoretically studied at the tight-binding approximation level. However, a systematic first-principles-based study of nanotubes that addresses these effects did not exist in the literature prior to the present work. This thesis aims at performing such a fundamental study. We first describe a method for calculating the dipole moments and transition rates in nanotubes. This also enables the study of selection rules, based on which a modified set of rules is defined. The probability of absorption is studied in the full range of infrared-visible-ultraviolet. We show that π-σ*, σ-π*, and σ-σ* transitions that are neglected in previous works are allowed and can lead to high probabilities of transition. We then investigate several effects caused by the curvature of the nanotube sidewall and their impacts on the optical properties. The overall effect is shown to not only depend on the diameter, but also on the chirality of the nanotube. Through the study of the light polarization effect, we show that the overall transition rate spectrum of the perpendicularly polarized light is suppressed for smaller-diameter nanotubes in the IR/VIS range. In the UV region, however, perpendicular polarization is generally absorbed at a higher rate compared to parallel polarization. Finally, we show how the absorption spectra of short nanotube segments can be different from those of long nanotubes. We examine the effect of length on individual absorption peaks and also investigate the effect of spin on the optical properties of nanotube segments. The calculation method described in this thesis and the results can be used to estimate the effects of structural and environmental factors on the optical absorption properties of nanotubes.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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Sripanyakorn, Supannee. "Silicon absorption and bone health." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417265.

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Crighton, Neil Physics Faculty of Science UNSW. "Cosmology with Quasar Absorption Lines." Awarded by:University of New South Wales. Physics, 2006. http://handle.unsw.edu.au/1959.4/30178.

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In this thesis we make a new measurement of the primordial deuterium abundance, and analyse five other systems selected as possible D/H candidates. We also undertake an investigation of systematic errors in a system where an existing deuterium measurement has been made. We measure the number of hydrogen components and their velocity distributions in a moderate and high redshift sample of Lyman limit systems in one Angstrom resolution spectra. We present a new measurement of the deuterium-to-hydrogen ratio, D/H, at z=3.2560 in a newly-discovered low metallicity absorption system towards the quasar PG1937-1009. We attempt to account for any systematic effects that could influence the D/H measurement. We find a 1 sigma range for D/H*1e5 of 1.6 (+0.25) (-0.30). Using high resolution spectra from the Hubble Space Telescope and the Very Large Telescope, we assess the suitability of five D/H candidate absorption systems. These systems were selected as candidates using lower resolution spectra. We measure the neutral hydrogen column density, identify metal lines and analyse the velocity structure of each system, and show them to be unsuitable for measuring D/H. We also investigate the systematic errors in the absorber at z=0.701 towards quasar PG1718-4801 that was initially thought to show a high primordial D/H value. We analyse the dependence of the putative deuterium line's parameters on wavelength calibration errors in the HST spectra and present a revised deuterium measurement. We examine the velocity widths of two samples of one Angstrom resolution quasar spectra showing Lyman limit absorption systems. The first sample is at high redshifts, taken from the Sloan quasar data release 3 catalogue. The second is at intermediate redshifts, compiled from a survey for UV quasar absorption systems taken with the Hubble Space Telescope. We use a modified version of the Voigt profile fitting program, VPFIT, to estimate the number of hydrogen velocity components and column density in the Lyman limit systems. We compare the velocity distributions of the higher and lower redshift samples. We find the distributions are consistent with other measures of the velocity spread in absorption systems, and find no compelling evidence for evolution between the redshift samples.

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Xia, Qi. "Gas absorption kinetics in STR's." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0032/NQ64694.pdf.

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Fischer, Nathan Lee. "Novel composites for microwave absorption." [Ames, Iowa : Iowa State University], 2008.

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Watanabe, Akira. "Case absorption and WH-agreement /." Dordrecht [u.a.] : Kluwer Acad. Publ, 1996. http://www.loc.gov/catdir/enhancements/fy0821/96029249-d.html.

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Zhang, Changjun. "Seismic absorption estimation and compensation." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2820.

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As seismic waves travel through the earth, the visco-elasticity of the earth's medium will cause energy dissipation and waveform distortion. This phenomenon is referred to as seismic absorption or attenuation. The absorptive property of a medium can be described by a quality factor Q, which determines the energy decay and a velocity dispersion relationship. Four new ideas have been developed in this thesis to deal with the estimation and application of seismic absorption. By assuming that the amplitude spectrum of a seismic wavelet may be modeled by that of a Ricker wavelet, an analytical relation has been derived to estimate a quality factor from the seismic data peak frequency variation with time. This relation plays a central role in quality factor estimation problems. To estimate interval Q for reservoir description, a method called reflectivity guided seismic attenuation analysis is proposed. This method first estimates peak frequencies at a common midpoint location, then correlates the peak frequency with sparsely-distributed reflectivities, and finally calculates Q values from the peak frequencies at the reflectivity locations. The peak frequency is estimated from the prestack CMP gather using peak frequency variation with offset analysis which is similar to amplitude variation with offset analysis in implementation. The estimated Q section has the same layer boundaries of the acoustic impedance or other layer properties. Therefore, the seismic attenuation property obtained with the guide of reflectivity is easy to interpret for the purpose of reservoir description. To overcome the instability problem of conventional inverse Q filtering, Q compensation is formulated as a least-squares (LS) inverse problem based on statistical theory. The matrix of forward modeling is composed of time-variant wavelets. The LS de-absorption is solved by an iterative non-parametric approach. To compensate for absorption in migrated seismic sections, a refocusing technique is developed using non-stationary multi-dimensional deconvolution. A numerical method is introduced to calculate the blurring function in layered media, and a least squares inverse scheme is used to remove the blurring effect in order to refocus the migrated image. This refocusing process can be used as an alternative to regular migration with absorption compensation.

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Falklöf, Olle, and Bo Durbeej. "Modeling of phytochrome absorption spectra." Linköpings universitet, Beräkningsfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92393.

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Phytochromes constitute one of the six well-characterized families of photosensory proteins in Nature. From the viewpoint of computational modeling, however, phytochromes have been the subject of much fewer studies than most other families of photosensory proteins, which is likely a consequence of relevant high-resolution structural data becoming available only in recent years. In this work, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are used to calculate UV-vis absorption spectra of Deinococcus radiodurans bacteriophytochrome. We investigate how the choice of QM/MM methodology affects the resulting spectra and demonstrate that QM/MM methods can reproduce the experimental absorption maxima of both the Q and Soret bands with an accuracy of about 0.15 eV. Furthermore, we assess how the protein environment influences the intrinsic absorption of the bilin chromophore, with particular focus on the Q band underlying the primary photochemistry of phytochromes.

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McFarland, Elizabeth Gramling. "Infrared absorption characteristics of fabrics." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/10185.

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Jacob, David. "Analytical analysis of absorption cycles." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16094.

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Bozkurt, Volkan. "Pentlanditepyrrhotite interactions and xanthate absorption." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34703.

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Xanthate interaction with pentlandite and pyrrhotite has been investigated in the case of single and mixed minerals in the presence of Ni ions and depressants such as meta-bisulfite (MBS), diethylenetriamine (DETA) and MBS plus DETA at two pHs controlled by lime and soda ash. It was found that dixanthogen was the main product and the surface concentration was consistently higher on pentlandite than on pyrrhotite. Ni ions enhanced the dixanthogen adsorption on both minerals in the case of single minerals. Mixed mineral experiments (i.e. pentlandite and pyrrhotite together) showed that dixanthogen formation on penlandite was promoted while on pyrrhotite it was suppressed, interpreted as due to a galvanic interaction between minerals. The ratio of dixanthogen adsorption on pentlandite to pyrrhotite increased to ca 4:1 compared to <2:1 for single minerals and this ratio was maintained in the presence of depressants; overall however, depressants reduced the dixanthogen adsorption on both minerals in the case of single and mixed minerals. For pentlandite in the mixed mineral case, this reduction returned dixanthogen adsorption to values similar to those on the single mineral in the absence of depressants. For pyrrhotite, dixanthogen was reduced below detectable limits. In terms of flotation, the mixture of minerals enhances dixanthogen formation on pentlandite at the expense of pyrrhotite. This is preserved on addition of depressants which serve to reduce the absolute dixanthogen adsorption on pyrrhotite perhaps below a critical level for flotation.
Xanthate adsorption on both minerals is reduced when the pH is adjusted by soda ash instead of lime. The general effects of depressants otherwise were similar regardless of pH modifier.
Open circuit potential measurements showed that pentlandite has a higher rest potential than pyrrhotite. In the presence of xanthate, however, the order was reversed. A mixed potential model was used to explain the effect of mineral interaction on dixanthogen formation. At the potential of the mixed mineral system, the anodic reaction (xanthate oxidation to dixanthogen) occurred preferentially on the pentlandite and the cathodic reaction (reduction of oxygen to hydroxyl ion) occurred on the pyrrhotite.
A new design of spectroelectrochemical external reflectance cell has been developed for in situ analysis under controlled electrochemical conditions. Orientation and stability of xanthate adsorption products on a copper electrode was studied as a model system. Cuprous xanthate was found to be the major product over the potential range --0.5 to --0.1 V (SCE). Further increase in potential to 0.1 V resulted in the formation of dixanthogen in addition to cuprous xanthate. It was also found that the characteristic dixanthogen bands disappeared when the potential was brought back and held at --1.0 V while the cuprous xanthate bands were enhanced. When polarized radiation was used, the appearance of the characteristic peaks of cuprous xanthate changed while that of dixanthogen remained the same, suggesting preferential orientation of the cuprous xanthate molecules but not of the dixanthogen. The probable orientation of cuprous xanthate is given.
In the stability study, the dixanthogen disappeared while the copper xanthate peaks intensified. The rate of dixanthogen disappearance was greater in the case of ex situ compared to in situ sampling conditions.

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Xia, Qi 1962. "Gas absorption kinetics in STR's." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36732.

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Experiments were carved out in a stirred tank reactor with both two phase and three phase systems. A systematic examination of the effect of solid particles on parameters such as volumetric liquid-side mass transfer coefficient kLa, specific interfacial area a, gas holdup epsilong, bubble size dB, and average bubble residence time tau, was conducted. Both dimensional and dimensionless correlations were generated and conclusions were drawn.
The work was carried out in the context of the industrial experience that stirred tank reactors are widely used in both metallurgical and chemical engineering processes that often involve gas absorption in two and three phase systems. The effect of solids loading on the oxygen absorption rate in stirred tank reactors is complex due to the interactions between bubbles and solid particles, and also between other parameters. The measurement of some parameters, such as bubble size, specific interfacial area, volumetric mass transfer coefficient, is difficult, and there are many discrepancies in the literature with respect to the form of the correlation for oxygen absorption rate and bubble size and also the explanation of the internal mechanisms.
The present work found that kLa decreased with increasing solids volume fraction. This decrease was as much as 50% when solids loading was increased from 0 (water) to 14 vol% at a superficial gas velocity of 0.64 cm/s and a impeller speed of 400 rpm. The primary reason for this was due to the enhancing effect of solids on bubble coalescence and the increase of slurry density. Kolmogroff's turbulence theory was proved not applicable to the present STR and conditions. The cause for this was believed to be due to the fact that the power density in the STR was far from homogeneous, and the dynamic equilibrium between bubble breakup and the bubble coalescence was not established.
Bubble size, dB, was found to be increased by increasing solids volume fraction. The increase was due to the direct enhancing effect of solids on bubble coalescence and due to less bubble recirculation, i.e., change of the bulk flow pattern, with increased solids loading. There was no direct relationship found between a change of the apparent viscosity of slurry and a change of bubble size. Therefore, the manner by which many people incorporated apparent viscosity into the correlation of dB is inappropriate.
To properly describe the extent of bubble coalescence in three phase systems, a new parameter, the coalescence factor, fc, was defined in the present work. It was found that the coalescence factor decreased with increasing solids volume fraction and power input, but decreased with increasing superficial gas velocity.

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36

Jailani, Fadhilah. "Absorption and metabolism of flavonols." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.634526.

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The consumption of flavonols, major sources of dietary flavonoids, have been linked to the reduction of risk factors for various chronic diseases. However, the bioavailability of flavonols would appear to be limited and not all compounds within the same subclass are absorbed with equal efficacy, thus compromising their nutritional relevance. The aim of this current study was to examine the absorption and metabolism of four major flavonols specifically quercetin, myricetin, kaempferol and galangin using both in vitro methods and healthy human volunteers to investigate how bioavailability was affected by the addition of other ingredients, specifically fat. Firstly, the enzymatic synthesis of flavonol metabolites was conducted using liver S9 homogenates, which demonstrated that all major flavonol aglycone generated several isomers of glucuronide or sulphate forms after the incubation period. The evidence for identification and characterisation of available authentic standards and synthesised flavonol metabolites using HPLC-DAD-MS-MS is presented. The success of this method was demonstrated through its application to assess the fate of flavonols in the cell culture transport experiments, which were examined using co-cultures of Caco-2 (enterocyte cell) and HT29-MTX (goblet cell) monolayers and the results partially substantiate that the absorption is most probably achieved by passive transport.

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37

Zhou, Xin Hua. "Characterisation of drug absorption barrier." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335622.

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38

Richardson, Julie Lynn. "The vaginal absorption of drugs." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277940.

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39

Ashton, P. "Surfactant effects in subcutaneous absorption." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380198.

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40

Traynor, Matthew John. "Dermal absorption of solvent mixtures." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427345.

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41

Duffield, Roger John. "Direct atomisation furnace atomic absorption." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236310.

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42

Morgan, Emma Louise. "Intestinal glucose and calcium absorption." Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424573.

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43

Lashmar, U. T. "Vehicle effects on percutaneous absorption." Thesis, Open University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370508.

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The availability of a drug from a topical preparation is dependent on many factors, one of the most important being the composition of the vehicle. Glycerol, propylene glycol and polyethylene glycol 200 are widely used as ingredients in topical formulations. The aim of this study was to examine how these glycols affected some of the fundamental factors involved in percutaneous absorption of ethyl- methyl- and glycol salicylate. To do this, certain drug-vehicle, drug-vehicle-skin and vehicle-skin interactions were investigated. Drug-vehicle interactions were evaluated using solubility - and rheological measurements, equilibrium dialysis, diffusion coefficient - and release rate determinations. In particular, the study showed that it is important to consider the viscosity contribution of a cosolvent to the vehicle and that it is essential not to over solubilise a drug in the vehicle. The evaluation of drug-vehicle-skin interactions involved both in vitro and in vivo determinations. The in vitro study consisted of solubility- and partition coefficient measurements together with determination of diffusion coefficients and penetration rates for the drugs and the glycols using a two compartment cell in which nude mouse skin was the rate controlling barrier. In vivo, the concentrations of the glycols were determined in the individual layers in the skin and in the plasma of nude mice. The flux of the salicylates was largely unaffected by the various solvent concentrations and the different solvents, except when high concentrations of propylene glycol and glycerol were employed. The measurements of glycerol and propylene glycol in the skin and plasma suggested that the amount of the glycols penetrating into the skin from a topical application were unlikely to have any effect on the partition coefficient of a drug between the vehicle and the skin or the diffusivity of the drug in the skin phase. A comparison of the in vivo and in vitro results indicated a good correlation between these studies. In vivo and in vitro histological assessment were employed to evaluate vehicle-skin effects. Applications of glycerol and PEG 200 had no effect on the skin, whereas increasing concentrations of propylene glycol caused progressive disintegration of the stratum corneum. Some `penetration enhancers' showed unacceptable levels of skin damage and/or irritancy. Future studies may correlate these findings with their penetration enhancing properties.

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44

Ahmadnia, Ali. "Energy absorption of macrocomposite laminates." Thesis, Queen Mary, University of London, 2000. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1342.

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The aim of this project was two-fold. Firstly to provide an understanding of the behaviour of SMC when subjected to drop weight impact and secondly to investigate the effect of a surface layer of a metallic material (stainless steel, aluminium, brass and copper) and a layer of Ionomer on the impact behaviour of SMC. Tensile, flexural, compression, shear, charpy and drop weight impact tests were carried out on SMC (Sheet Moulding Compound). The response of SMC and various combinations of SMC and metal sheet (stainless steel, aluminium, brass and copper) and SMC with a layer of Ionomer to impact load have been assessed using an Instrumented Falling Weight Impact test machine. Slow indentation tests and a variety of destructive and non-destructive test techniques were used to monitor the initiation and propagation of damage and relate them to the major features of typical force-time curves obtained during impact. The deformation of the metallic layer was compared under impact and slow test and a calibration curve was produced. By using the calibration curve the energy absorbed by SMC and SMC as a layer in SMC+metal laminate was compared and results were related to stiffness and ductility of the metallic layer. The energy absorbed by the SMC-metal laminates were analysed and the energy absorbed by each constituents was determined. The effect of impact damage on tensile and compressive residual strength was assessed by conducting tension and compression test on the damaged specimens. Finally, a number of simple models and fInite element technique were used to predict the impact response of SMC and SMCmetal laminates to impact. The results of the research programme indicated a strong macrocomposite effect resulting in greatly improved energy absorbing capabilities for SMC. The indications were that a metal layer was required that would be stiff, thereby putting the SMC into compression and also ductile in order to support extensive deformation in the SMC whereby microcracking could accumulate.

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PEREIRA, KARINE RIBEIRO. "SEISMIC ABSORPTION AND CORRECTION METHODS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25659@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Este trabalho tem como objetivo analisar o problema das perdas por absorção dos dados de reflexão sísmica, bem como testar três métodos disponíveis na literatura para sua correção. Utilizamos a modelagem da absorção apresentada por Romanelli Rosa, com a noção de frequência instantânea, e analisamos os seguintes métodos de correção: a Compensação Q, o método de Varela et al. e o método de Duarte, que é um filtro recursivo. Observamos que o método de Duarte é computacionalmente mais rápido que os demais. Ainda assim, podemos utilizar a Transformada de Fourier para torná-lo mais rápido nos casos em que a recursão é interrompida em uma etapa M, menor que o número de amostras N do dado sísmico e maior que lnN. Por fim, testamos o desempenho dos métodos em uma linha de reflexão sísmica marítima da Bacia de Sergipe-Alagoas, fornecida pela Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP). A linha foi reprocessada, com a correção das perdas por absorção aplicada antes do empilhamento, para cada método estudado. Para comparar os resultados, o dado também foi processado sem correção da absorção. Verificamos que houve um aumento da resolução das camadas geológicas de subsuperfície em todos os métodos testados em comparação com o dado sem correção, porém o método de Duarte mostrou-se mais rápido que os demais.
This work aims at analyzing the problem of losses by absorption in seismic reflection data and test three correction methods available in the literature. We use the modeling of the absorption presented by Romanelli Rosa, with the concept of instantaneous frequency, and analyzed the following correction methods: Q compensation, Varela s method and Duarte s method, which is a recursive filter. We note that Duarte s method is computationally faster than the others. However, we can use the Fourier Transform to make it faster in cases where the recursion is interrupted at a step M, smaller than the number of samples N in the seismic data and greater than ln N. Finally, we test the performance of the methods in a marine seismic line in Sergipe-Alagoas Basin, provided by the Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP). The line was reprocessed, with the correction of the losses by absorption applied before stacking, for each method studied. In order to compare the results, the data was also processed without correction of absorption. We observe an increase in the resolution of the geological subsurface in all methods tested in comparison with the data without correction. We also observe the computational advantage of Duarte s method.

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JÖNSSON, EMMA. "A comparison of absorption methods." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17480.

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This report is an attempt to find an absorption method that is more suitable for IKEA. Several different methods and standards from around the world are compared to see their pros and cons. The methods are compared both theoretically and practically. The practically comparison is made in a round robin were 14 different fabric is tested in three different methods. Two of the methods in the round robin are compared against each other and the result from a home test to see if the methods can show what the customer experience. The results from the round robin is used to recommend a proper method and requirement level that suit IKEA the best, based on their demands and requirements.
Program: Magister i textilteknologi

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47

Hageman, Stephen James. "Complex Attosecond Transient-absorption Spectroscopy." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1608050018545904.

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48

Fleshman, Matthew Kintz. "β-Carotene Absorption and Metabolism." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313548706.

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49

Sanderson, Francis D. "Absorption models of drug delivery." Thesis, Aston University, 1986. http://publications.aston.ac.uk/12457/.

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50

Partridge, Stephen. "The gastrointestinal absorption of lead." Thesis, Aston University, 1986. http://publications.aston.ac.uk/14504/.

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Dissertations / Theses on the topic 'Absorption'

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