Дисертації з теми "Analyte"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Analyte.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Analyte".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Mulrooney, Ray. "Analyte sensing with luminescent quantum dots." Thesis, Robert Gordon University, 2009. http://hdl.handle.net/10059/452.
Повний текст джерелаАнотація:
Semiconducting nanocrystals otherwise known as Quantum Dots (QDs) have attracted considerable attention over the last number of years due to their unique optical properties and potential applications. Their narrow size-tunable emission spectra, broad absorption spectra, resistance to photobleaching and long fluorescent lifetimes make them ideal for sensing ions and small molecules. This thesis explores the potential of QDs to function as the emissive unit in fluorescent probes. Primarily, the focus of the work is to develop QD-based sensors that operate through an electron transfer mechanism. Chapter 3 discusses the synthesis and characterisation of CdSe and CdSe/ZnS QDs. Three different sized QDs were prepared each with distinct emission wavelengths. The sizes of these nanoparticles were determined by three methods, transmission electron microscopy (TEM), dynamic light scattering (DLS) and by a UV-vis method. Surface functionalisation of these synthesised QDs (chapter 4) with mercaptosuccinic acid rendered them water soluble and were shown to display selectivity for Cu2+ over a number of biologically relevant metal ions. The negatively charged surface of the QDs and the position of copper in the Irving-William series were believed to be responsible for this interaction. Positively charged CdSe/ZnS QDs were also prepared and were shown to detect ATP and to a much lesser extent GTP over the other nucleotides screened. The greater net negative charge of the ATP and GTP when compared to their mono and diphosphate analogues was the likely cause of this discrimination. In chapter 5 the relatively unexplored field of anion sensing with QDs was examined using charge neutral urea and thiourea receptors. Based on a design by Gunnlaugsson et al, a CdSe/ZnS QD with a thiourea receptor anchored to its surface displayed similar PET-mediated fluorescence quenching as an organic dye sensor containing the same receptor. A ferrocenyl urea receptor was also anchored to a QD surface and shown to “switch off” the QD’s fluorescence emission. On addition of fluoride ions the emission was restored, most likely due to a modulation of the ferrocene’s redox activity. In chapter 6 the assembly of Schiff base receptors on the surface of preformed CdSe/ZnS QDs were shown to arrange in such a way to enable the simultaneous detection of Cu2+ and Fe3+. The intriguing aspect of this study was that the receptors themselves displayed no selectivity for any metal ion until they were assembled on the QDs. Recognition was also confirmed by a distinct colour change visible to the naked eye.
2
Taylor, Carolyn. "Multi-analyte immunoassays for drugs of abuse." Thesis, University of Sunderland, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251355.
Повний текст джерелаАнотація:
Currently, many methods are available for the analysis of drugs of abuse in urine but they all have their drawbacks. Thus, the purpose of this research was to overcome some of these drawbacks by developing multi-analyte detection systems based on sequential or spatial techniques and immunoassays. The first system was based on a spatial technique and involved a simple indirect competitive ELISA format. This produced relatively rapid multi-analyte dip-strip ELISAs for benzoylecgonine (BE), methadone (MET) and morphine (MOR). Various enzyme-labelled antibodies, substrates and filters were investigated. A multi-analyte dip-strip assay was developed based on cellulose nitrate filters, alkaline phosphatase labelled anti-mouse second antibody and nitro blue tetrazolium / 5-bromo-4-chloro-3- indoyl phosphate (NBT /BCIP) substrate. The resulting assays gave a simple 'yes/no' result when drug was present or absent from a sample at concentrations of 1.45 f,lg ml-I , 1.55 f,lg ml-I and 1.43 f,lg ml-I for BE, MET and MOR respectively. Limitations however were encountered that caused the concentrations to be above the accepted cutoff levels for these three drugs of abuse. The second system was based on a sequential technique and involved a flow-injection nnmunoassay (FIlA). Various monoclonal antibodies, fluorotracers and immobilisation methods were investigated. For morphine, a novel simple FIlA was developed which is based on competition between a mixture of a fluorescein derivative of the drug and morphine in flow over low affinity monoclonal morphine antibodies immobilised on a N-hydroxysuccinimidyl chloroformate activated agarose immunoreactor. With this system, a split peak profile (unbound and retarded fractions) was observed under isocratic conditions with the retarded peak disappearing and the unbound peak increasing in peak height/area as the concentration of morphine increased. Using a flow-rate of 0.5 ml min-I and a fluorescein derivative dilution of 1: 100, this assay had a sample throughput of 4 samples h-I and a detection limit of 14.1 f,lg ml- I . For a flow-rate of 1.6 ml min-I and a fluorescein derivative dilution of 1: 1 00,the assay had a sample throughput of 6 samples h-I and a detection limit of 10.9 J.!g mri. The origin of the phenomenon was investigated and revealed to be due to the low association rate of the drug tracer with the morphine antibody used and the near equivalence of the monoclonal antibody affinity for its respective tracer and drug. It was found that when these values are exceeded, the "split peak" phenomenon was not observed but the reagents could be used in conventional displacement flow injection fluoroimmunoassays as was demonstrated for benzoylecgonine and methadone.
3
Yamazaki, Miki. "Novel technologies for high sensitivity analyte detection." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9999.
Повний текст джерелаАнотація:
Microfluidic devices are attracting interest for point-of-care diagnostics due to their low unit cost, low reagent and sample usage, fast analysis times and portability. Fluorescence is the most widely used detection method in microfluidics due to its high sensitivity, excellent dynamic range, ease of implementation and non-invasive nature. Fluorescence detection has accordingly been widely used for the interrogation of microfluidic devices, with the majority of reports to date having used non-integrated laser excitation sources coupled with off-chip optics and photodetectors. For point-of-care applications, there is a growing need for self-contained systems which incorporate the microfluidic chip and all associated optical components into a compact, low-cost package. Highly compact systems of this kind would eliminate the need for expensive dedicated bench-top instrumentation. As such they would find multiple uses in the home, ambulance and GP’s surgery, where their ability to provide immediate and/or frequent testing would enable faster, more responsive and ultimately more successful treatment. Work undertaken in this thesis focuses on developing highly sensitive analyte detection systems that would enable the use of cheap optical and electronic components. To accomplish this, two separate methods, based on optical filters and time-gated detection of phosphorescent polymer beads, were investigated. We describe a simple technique for fabricating non-emissive colour filters based on the sensitisation of a highly porous nanostructured metal-oxide film with a monolayer of dye molecules. The resultant filters exhibit much less autofluorescence than conventional colour filters, and are a viable low cost alternative to interference filters. In separate work Ru(dpp)3-doped polystyrene/bisphenol A diglycidyl ether polymer phosphorescent beads developed by Dr. Edwards (Imperial College London) were used to demonstrate the feasibility of highly sensitive of low-cost time-gated detection. This method was applied to a simple biotin assay to show their bio-assay applicability.
4
Tran, Ngoc L. "A fundamental study on analyte adsorption onto metallophthalocyanines." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3336474.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed Dec. 16, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 91-101).
5
Zhu, Tong. "Preparation of enzyme-analyte conjugates containing linker arms /." Online version of thesis, 1995. http://hdl.handle.net/1850/12161.
Повний текст джерела
6
Guo, Jiu-Chun. "The development of simultaneous multi-analyte fluorescence immunoassays." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/32926.
Повний текст джерелаАнотація:
Fluorescence immunoassays have been established for a number of years as valuable methods of analysis in clinical chemistry and other fields, being sensitive, safe, easy to use and available in a variety formats. Those in common use are normally single analyte assays. But in many cases (e.g. forensic drug screening, therapeutic drug monitoring, screening for cancer markers, monitoring of thyroid function, or the analysis of environmental pollutants) dual- or multi-analyte assays would be much more valuable, with the advantages of increased information content, savings in time and costs, and the elimination of some sources of sampling variance. Amongst all the labels used in immunoassays, only fluorescent groups offer realistic prospects of practicable multi-analyte assays. This project has investigated single-, dual- and multi-analyte fluorescence immunoassays using several spectroscopic and software methods to resolve multicomponent fluorescence emission or synchronous spectra. The assays have been based on flow injection analysis methodology, with solid phase reactors to effect the separation of antibody-bound and unbound labelled analytes. The use of solid phase reactors incorporating thiophiIic gels to bind antibodies has also been investigated: these stationary phases have the advantage that bound antibodies can be eluted by changes of ionic strength, rather than changes of pH. This allows the use of a much wider range of fluorescence labels, clearly important in multi-analyte assays, and it has thus proved possible to develop successful dual and triple analyte assays, with results that compare well with other independent methods.
7
Ranganathan, Lavakumar. "Sensor-array chip hybrid for simultaneous multiple analyte detection /." Full text open access at:, 2007. http://content.ohsu.edu/u?/etd,260.
Повний текст джерела
8
Easter, Renee N. "The application of elemental tags for biological analyte identification." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307043953.
Повний текст джерела
9
Pihlblad, Alma. "Development and comparison of bioanalytical methods to measure free analyte." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413669.
Повний текст джерелаАнотація:
Free analyte is measured to be able to understand the pharmacological effects of a drug in the body, the binding to its ligand, and the effective drug level among other things. Thereby, it is important with correct measurements of free analyte, although it is not that easy to achieve since overestimations can occur. In this project, several immunoassays were developed for the bioanalytical methods Gyrolab and ELISA to measure free analyte, where the biotherapeutics Avastin® and Lucentis®, and the ligand VEGF were used as analytes. One difference between the methods is the short contact time of just a few seconds for Gyrolab compared to the sample incubation time of a couple of hours for ELISA. One difference between the antibodies is that Lucentis is an affinity-matured Fab region, and therefore, has a stronger affinity to VEGF compared to Avastin. When free Avastin was measured, the difference was significant, with ELISA estimating higher concentrations compared to Gyrolab. However, this was not the case for all assays. In some cases, this was probably due to differences between the methods that could not be seen. Otherwise, the results with no difference between the methods, when measuring free analyte with Lucentis as the drug, were expected due to the stronger affinity and longer halftime of dissociation. However, the difference with the longer sample incubation time for ELISA compared to the short contact time for Gyrolab seems to influence the measurement of free analyte, depending on the affinity of the components being measured.
10
Andria, Sara. "Spectroelectrochemical Sensing: Novel Thin Film Characterization and Multiple Analyte Detection." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1253548394.
Повний текст джерела
11
Jacob, Silvana do Couto. "Studies of a microporous membrane for analyte preconcentration and separation." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/6846.
Повний текст джерелаАнотація:
A dual phase gas diffusion-FIA system containing a tubular PTFE-membrane was studied as a mean of producing gas samples for routine 15N/14N isotopic ratio mass spectrometry. The method is based on Rittenberg's reaction; the ammonium sample is injected into a liquid alkaline stream containing hypobromite and the N2 gas produced in the reaction diffuses across a PTFE-membrane into a helium carrier stream which carries it to the detector. Initially here, the use of a tubular microporous PTFE-membrane as a device for the preconcentration of samples in aqueous solutions was investigated. The performance of such a membrane was studied under a variety of operating conditions. A qualitative model of the membrane mechanism was developed based on the diffusion transport of vapour away from the contained liquid surface through the connected pore space. The dispersion undergone by the sample in the GD-FIA system containing this preconcentration unit was also studied and this FIA system was applied as a practical device for the determination and speciation of aluminium in a river water sample. The procedure for generating nitrogen gas involved optimisation of the system parameters including the oxidation reaction step and the production on-line of the chemicals used. The nitrogen gas was generated easily and rapidly, allowing a sample throughput capability of the order of 20 h-1. The system was applied to the determination of total nitrogen content in agricultural sample prepared by the Kjeldahl digestion. The method offered precision and accuracy comparable to those of the standard distillationtitration procedure. Isotope ratios were determined with good precision and means for obtaining accuracy comparable with established techniques were developed. It was also shown that the DPGD-FIA system can be readily adapted to enable different forms of nitrogen e. g. N02-, N03- and NH4+ to be determined.
12
Caughlin, Brenda Lea. "Analyte excitation and ionization in the argon inductively coupled plasma." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27038.
Повний текст джерелаАнотація:
A new approach to evaluating departures from local thermal equilibrium (LTE) in the inductively coupled plasma (ICP) is described. Experimentally evaluated electron density (n[sub e]) is used as the basis for an LTE framework.
Spatially resolved, radial electron density profiles were measured under a variety of plasma operating conditions. The variation of n[sub e] with spatial position, aerosol flow rate, input power and presence of easily ionizable elements was determined. The measured n[sub e] was used to calculate an LTE temperature, T[sub e,LTE]. This temperature was higher than most spectroscopically measured temperatures in the plasma.
LTE ion-atom emission intensity ratios for Sr, Ca, Mg, Cd and Zn were calculated from n[sub e] and T[sub e,LTE] compared to experimental values. Ion-atom ratios were within an order of magnitude of LTE values and, in most cases, less than the LTE values. The infrathermal ion-atom ratios were interpreted as being due to an overpopulation of the atom levels relative to LTE populations.
Experimental degree of ionization was evaluated for a number of elements and compared to LTE values. Elements were underionized relative to LTE values. Degree of ionization and departure from LTE were correlated with ionization potential of the element. Elements with a high ionization potential had lower degrees of ionization and exhibited greater departures from LTE than elements of lower ionization potential.
The underionization and infrathermal ion-atom intensity ratios are attributed to overpopulation of atom levels. The experimental observations and results of other plasma diagnostic studies are discussed in terms of a partial LTE (p-LTE) model for the ICP. The ion ground state and upper energy levels of atoms are in Saha equilibrium. Lower atomic levels are over populated with respect to these levels. The overpopulation of the lower levels is a consequence of radiative depopulating processes, such as radiative decay and radiative recombination, not being balanced by their inverse absorption processes. For low lying atomic levels where radiative processes make significant contribution to the total depopulation rates this improper balance causes deviations from LTE populations. The atom ground state is the most overpopulated level and overpopulation decreases with increasing energy of the level until p-LTE is reached for the upper atomic levels.Science, Faculty of
Chemistry, Department of
Graduate
13
Troiani, David. "Analyte sensitive ultrasound contrast agents based on molecularly imprinted nanogel sensors." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106230.
Повний текст джерелаАнотація:
Recently developed ultrasound contrast agents provide traditional ultrasound techniques with highly localized contrast within samples depending on contrast agent concentration. Contrast agents resonate at characteristic frequencies, allowing background signals in backscatter collected from samples to be easily removed through filtration, leaving only resonance from contrast agents remaining. The goal of this thesis was to develop analyte sensitive contrast agents based on molecularly imprinted poly(N-isopropylacrylamide) (pNIPA) nanogel polymers. Molecularly imprinted pNIPA was synthesized in presence of target analyte theophylline. Ultrasonic analysis of pNIPA behavior in the presence of varying theophylline concentration revealed amplitude changes at various frequencies. Analysis of chemically similar caffeine demonstrated ultrasonic changes at different frequencies.Solutions containing increasing amounts of theophylline in the 8.4 to 167 μM range with 1% by weight molecularly imprinted pNIPA in water were analysed ultrasonically. Concentration models displayed very high linearity (r2 coefficient exceeding 0.99). Additional concentration models were constructed in a matrix of solutions containing both the imprinted analyte theophylline, and interferant caffeine. Regression models for the two analytes demonstrated good linearity in the micromolar range (r2 of 0.98 for theophylline, 0.87 for caffeine) using different subsets of frequencies for each analyte.A tighter binding arrangement between analyte and pNIPA was achieved through synthesis of molecularly imprinted pNIPA in the collapsed phase. This increased analyte sensitivity and linear range to nanomolar concentrations. Quantification assays were carried out on a dopamine oxidation product, (5-6-dihydroxyindole, DHI), from 16.7 to 163 nM. High linearity was obtained (r2 correlation coefficient exceeding 0.99). The experiment was repeated in a presence of albumin, a biologically relevant interferant, with good agreement between actual and estimated concentration.Multi-analyte quantification was improved by combining two differently imprinted pNIPA nanogels to form multiplexed nanogels. Simultaneous quantification assays were carried out for theophylline (8.4 to 49 uM) and DHI (48.8 to 176 nM). Good linearity between estimated and actual concentrations were obtained (r2 of 0.99 for DHI, 0.96 for theophylline).Determination of a larger analyte, tobacco mosaic virus (TMV), was also carried out. Concentration models in the 9 to 140 ppb range showed excellent linearity (correlation coefficients exceeding 0.99). The process was repeated in presence of another virus, tomato bushy stunt virus (TBSV), acting as an interferant. Similar linearity was obtained.Critical points of the ultrasound quantification system based on molecularly imprinted nanogels are summarized in the Conclusion chapter. Improvements focusing on obtaining stronger ultrasonic signals in aforementioned analyses are discussed in the Future Works section.Le développement des agents de contraste ultrasonique ont produit des agents qui fournissent du contraste très élevé et localisé dans l'échantillon, selon la concentration des agents. Ces agents résonnent avec des fréquences particulières, et facilitent la soustraction du bruit par filtration, qui laissent seulement le résonance des agents. Le but de cette thèse est de développer des agents de contraste capable de quantifier des analytes en utilisant des polymères poly(N-isopropylacrylamide) (pNIPA) imprimés avec des molécules cible comme point de départ. La synthèse des polymères pNIPA était faite en présence de la molécule théophylline. L'analyse ultrasonique de pNIPA en présence de differentes concentration de théophylline conduit à des changements d'amplitudes à plusieurs fréquences. L'analyse de pNIPA avec de la caféine a produit des changements à d'autres fréquences. Des solutions avec théophylline (8.4 à 167 μM) et 1% massique de pNIPA imprimé avec théophylline ont été analysées avec le système ultrasonique. Les modèles de concentration que cette analyse a produit ont un très haut niveau de linéarité (r2 plus que 0.99). Plusieurs modèles de concentration ont été construit avec une matrice de solution qui contenait théophylline et caféine. Les modèles de régression pour les deux analytes ont démontrés de la linéarité dans les concentrations micromolar (r2 de 0.98 pour théophylline, 0.87 pour caféine), utilisant différentes fréquences pour chaque analyte.Une affinité plus grande entre l'analyte et pNIPA a été gràce à la synthèse avec du pNIPA comprimé. Cela a élevé la sensibilité aux concentrations nanomolaires. Des quantifications d'un produit d'oxidation de la dopamine (5-6-dihydroxyindole, DHI) de 16.7 à 163 nM ont été faites. Les résultats ont démontrés une très bonne linéarité (r2 plus que 0.99). L'expérience a été reproduite avec de l'albumine dans chaque solution, encore avec des bons résultats.La quantification de plusieurs analytes simultanément a été améliorée avec la combinaison de deux nanogels pNIPA imprimés avec les différentes analytes. Les analyses de concentration ont été menées en parallèle pour la théophylline (8.4 à 49 uM) et le DHI (48.8 à 176 nM). Les concentrations estimées étaient en accord avec les concentrations actuelles (r2 de 0.99 pour DHI, 0.96 pour théophylline).Un analyte plus large, le virus tabac mosaïque (TMV), a été detecté avec le système ultrasonique. Des modèles de concentration de 9 à 140 ppb ont démontrés un très haut niveau de linéarité (r2 plus que 0.99). Le processus a été répeté avec un autre virus, tomate bushy stunt (TBSV), ajouté aux solutions de TMV avec des résultats semblables. Les aspects critiques du système de quantification ultrasonique sont récapitulés dans le chapitre de conclusion. Des améliorations pour obtenir des signaux plus fort dans les analyses ultrasoniques sont discutés dans la section futur.
14
Reschke, Kathleen C. "Development of nanofluidic/microfluidic interfaces as analyte concentrators for proteomic samples." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/11161.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains xii, 124 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
15
Harrington, Helen. "The development of analyte responsive nanosensors for application within regenerative medicine." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537688.
Повний текст джерела
16
Choi, Woo-Hyuck. "Needle-Type Sensor For In Situ 3-D Multi-Analyte Mapping." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321641570.
Повний текст джерела
17
Kakkar, Nikhil. "Mixed-Signal IC design for Heterogeneously Integrated Multi-Analyte Chemical Sensor Arrays." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/36247.
Повний текст джерелаАнотація:
Wireless sensor nodes are emerging in a wide range of critical applications such as environmental monitoring, health applications, home automation and military surveillance and reconnaissance. The addition of low power wireless capability to such sensor nodes allows communication between a node and a base station or between nodes, resulting in the formation of wireless sensor networks. Sensor networks can use the information available from the distributed sensor nodes to determine the location and nature of a stimulus or environmental condition. The information collected by the base station can be used to determine the appropriate course of action for dealing with the stimulus. In chemical/biological defense or safety monitoring scenarios, wireless sensor networks can be used to identify and track harmful chemical or biological agents which might be present in a particular area. Due to the potentially remote areas that wireless sensor networks aim to cover, it is essential to minimize the power consumption of a sensor node so that it can operate over a long period of time without a connection to the power grid. Sensor nodes can contain multiple blocks, such as the readout circuit which interfaces with the sensor, an embedded processor, and the wireless transceiver circuits, all of which need to operate on a low power budget.
This thesis specifically focuses on design of low power mixed signal readout circuits which interface with chemoresistive chemical sensors, i.e. sensors that demonstrate a variation of resistance (or impedance) in the presence of chemical agents. For this thesis, the sensor can be either a chemoresistive bead or a nanowire. By integrating multiple non-specific chemoresistive sensors together in arrays, a cross-reactive array can be realized, where the combined response of the arrayed sensors can be used to determine analytes present in a mixture even if their concentrations are low.
In this thesis, a CMOS resistive readout circuit based on a sigma-delta ADC is presented. The design is used to measure the resistance of chemoresistive beads and nanowires with respect to time. The frequency of the ADC output varies as the resistance of a sensor changes and, based on the magnitude and duration of the variation, the type of chemical agent and its concentration can potentially be estimated. For future cross-reactive sensor applications, an array of 16x16 sites is also included in the readout circuit design. Individual sites in the sensor array can be accessed using addressing blocks which designed to select a particular row and column using an 8-bit addressing system. This thesis also covers the techniques used for integration of chemoresistive beads and nanowires into the array locations provided on the prefabricated CMOS IC. Measurement results that demonstrate the operation of the resistive readout circuitry are presented.
Finally, a second readout circuit is proposed to measure complex impedance variations of a sensor device. Measurement of magnitude and phase changes of a sensor device can provide another degree of freedom in the analysis of chemical mixture. Simulation results demonstrating the functionality of the proposed impedance measurement system are also presented.Master of Science
18
Lee, Jongchun. "Measurement uncertainty in contaminated land investigations related to analyte concentration and cost." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/8589.
Повний текст джерела
19
Ratterman, Michael E. "Multi-analyte Lab on a Chip Detection Utilizing Optical and Electro-chemical Methods." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305840.
Повний текст джерела
20
Hawkins, Kenneth R. "Designing the diffusion immunoassay (DIA) : how properties of the analyte affect DIA performance /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/8076.
Повний текст джерела
21
Huynh, Vivian. "Forensic Analysis of Ink on Documents Using Direct Analyte-Probed Nanoextraction Coupled Techniques." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849635/.
Повний текст джерелаАнотація:
Analzying questioned documents in a nondestructive nature has been an issue for the forensic science community. Using nondestructive techniques such as video spectral comparator does not give reliable information due to the variations in gray or color levels that are distinguished differently by analysts. Destructive techniques such as chromatography give dependable, qualitative and quantitative, information but involves altering the evidentiary value of these questioned documents. The paradox of document examination becomes a problem when document evidence is involved, especially when trying to preserve its evidentiary value and critical data is needed. Thus, a nondestructive technique has been developed to solve the loopholes in document examinations.
Direct analyte-probed nanoextraction (DAPNe) is a nanomanipulation technique that extracts ink directly off the document for further examination. A watermark is left, at most, post-extraction. DAPNe utilizes a tip emitter, pre-filled with a solvent, which is controlled in x-, y-, and z-coordinates via joystick controller and aspirates/extracts using a pressure injector. The versatility of this technique lies within the solvent chemistry and its capability to be coupled to various types of instrumentation. The extraction solvent can be altered to target specific components in the ink. For example, a chelator may be added to target metal ions found in ancient inks or methanol may be added to target certain organic resins and binding agents found in modern inks. In this study, DAPNe has been coupled to nanospray ionization mass spectrometry, fluorescence microscopy, Raman spectroscopy, matrix-assisted laser desorption ionization mass spectrometry, and laser ablation to solve questioned document concerns in the area of falsified or forged documents, redacted documents, and aging studies.
22
Gupta, Samit Kumar. "Development of a planar immunoFET which detects protein analyte in high salt environments." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290575121.
Повний текст джерела
23
Lee, Jin-Hwan. "MEMS Needle-Type Multi-Analyte Microelectrode Array Sensors for In Situ Biological Applications." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212146149.
Повний текст джерела
24
Chae, Mi-Young. "Synthesis and study of conjugate fluorescence probes for analyte detection in aqueous solutions /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487841548270506.
Повний текст джерела
25
Harvey, Daniel Peter. "The combination of smart hydrogels and fibre optic sensor technology for analyte detection." Thesis, Aston University, 2011. http://publications.aston.ac.uk/15806/.
Повний текст джерелаАнотація:
The subject of investigation of the present research is the use of smart hydrogels with fibre optic sensor technology. The aim was to develop a costeffective sensor platform for the detection of water in hydrocarbon media, and of dissolved inorganic analytes, namely potassium, calcium and aluminium. The fibre optic sensors in this work depend upon the use of hydrogels to either entrap chemotropic agents or to respond to external environmental changes, by changing their inherent properties, such as refractive index (RI). A review of current fibre optic technology for sensing outlined that the main principles utilised are either the measurement of signal loss or a change in wavelength of the light transmitted through the system. The signal loss principle relies on changing the conditions required for total internal reflection to occur. Hydrogels are cross-linked polymer networks that swell but do not dissolve in aqueous environments. Smart hydrogels are synthetic materials that exhibit additional properties to those inherent in their structure. In order to control the non-inherent properties, the hydrogels were fabricated with the addition of chemotropic agents. For the detection of water, hydrogels of low refractive index were synthesized using fluorinated monomers. Sulfonated monomers were used for their extreme hydrophilicity as a means of water sensing through an RI change. To enhance the sensing capability of the hydrogel, chemotropic agents, such as pH indicators and cobalt salts, were used. The system comprises of the smart hydrogel coated onto an exposed section of the fibre optic core, connected to the interrogation system measuring the difference in the signal. Information obtained was analysed using a purpose designed software. The developed sensor platform showed that an increase in the target species caused an increase in the signal lost from the sensor system, allowing for a detection of the target species. The system has potential applications in areas such as clinical point of care, water detection in fuels and the detection of dissolved ions in the water industry.
26
Lavigne, John James. "Molecular recognition and molecular sensing : single analyte analysis and multi-component sensor arrays for the simultaneous detection of a plethora of analytes /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерела
27
Chiu, May Leung. "Investigation and characterization of analyte-reporter enzyme conjugates for the enzyme-multiplied immunoassay technique." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1930910331&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Повний текст джерела
28
Adegoke, Oluwasesan. "The design of quantum dots and their conjugates as luminescent probes for analyte sensing." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1010866.
Повний текст джерелаАнотація:
The design and applications of quantum dots (QDs) as fluorescent probes for analyte sensing is presented. Cadmium based thiol-capped QDs were employed as probe for the detection of analytes. Comparative studies between core CdTe and core-shell CdTe@ZnS QDs showed that the overall sensitivity and selectivity of the sensor was dependent on the nature of the capping agent and the QDs employed, hence making CdTe@ZnS QDs a more superior sensor than the core. To explore the luminescent sensing of QDs based on the fluorescence “turn ON” mode, L-glutathione-capped CdTe QDs was conjugated to 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4AT) to form a QDs-4AT conjugate system. The QDs-4AT nanoprobe was highly selective and sensitive to the detection of bromide ion with a very low limit of detection. Subsequently, metallo-phthalocyanines (MPcs) were employed as host molecules on the surface of QDs based on the covalent linking of the QDs to the MPc. Elucidation of the reaction mechanism showed that the fluorescence “turn ON” effect of the QDs-MPc probe in the presence of the analyte was due to axial ligation of the analytes to the Pc ring. Studies showed that the type of substituent attached to the MPc ring influenced the overall sensitivity of the probe. Additionally, a comparative investigation using newly synthesized phthalocyanine and triaza-benzcorrole complexes was conducted when these complexes were conjugated to CdSe@ZnS QDs for analyte sensing. Results showed that the triaza-benzcorrole complex can be employed as a host-molecule sensor but displayed a lower sensitivity for analyte sensing in comparison to the phthalocyanine complex.
29
Mohammad, Avaes. "Study into the effect of water and analyte concentration upon differential mobility spectrometry responses." Thesis, University of Manchester, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548663.
Повний текст джерела
30
Chatterjee, Debolina. "Simple, Label-Free and Non-Instrumented Analyte Quantitation by Flow Distance Measurement in Microfluidic Devices." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4234.
Повний текст джерелаАнотація:
Rapid determination of the concentrations of molecules related to diseases can provide timely information for treatment options. However, most biomarker quantitation methods require costly and complex equipment. On the other hand, point-of-care systems have less complex instrumentation needs than laboratory-based equipment, but often provide less information; for example, biomarker presence or absence instead of concentration. A complete analysis setup addressing key limitations of both laboratory-based and portable systems is highly desirable. I developed microfluidic devices with visual inspection readout of a target’s concentration from microliter volumes of solution flowed into a microchannel. Microchannels are formed within polydimethylsiloxane (PDMS), and the surfaces are coated with receptors. Capillary flow of target solution in the channel crosslinks the top and bottom surfaces, which constricts the channel and stops flow. The flow distance of the target solution in the channel before flow stops indicates the target’s concentration, enabling simple visual inspection readout without complex detection instrumentation. Because of its easy readout and portability, my system has great potential for use in point-of-care diagnostics. I initially demonstrated a proof-of-concept assay using biotin-streptavidin. Solution capillary flow distances scaled linearly with the negative logarithm of streptavidin concentration over a 100,000-fold range. I measured streptavidin concentrations as low as 1 ng/mL using these microsystems, demonstrating low detection limits. I also characterized the mechanism wherein time-dependent channel constriction in the first few millimeters leads to concentration-dependent flow distances. I demonstrated the visual detection and quantification capability of my system to determine an antigen target, thymidine kinase 1 (TK1). I developed surface modification methods for carrying out flow assays and verified receptor attachment on channel surfaces using fluorescence imaging. I obtained a 1 ng/mL TK1 detection limit in flow assays. I also demonstrated nucleic acid quantitation in my flow devices. I detected specific DNA targets in buffer and synthetic urine at 10 pg/mL levels. A dynamic range of 106 was obtained with single-base mismatch specificity. DNA analogues of two miRNA biomarkers were measured near clinically significant levels, showing great promise for future medical application. The promising results demonstrate that this diagnostic tool offers a simple route to analyte quantitation in microliter volumes, with excellent potential for point-of-care application.
31
Twine, Nicholas B. "Open Nanofluidic Films with Rapid Transport and No Analyte Loss for Ultra-Low Sample Volumes." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535633706613122.
Повний текст джерела
32
Al-Karawi, Dheyaa Hussein. "The Investigation of The Electrical Control of Hemimicelles and Admicelles on Gold for Analyte Preconcentration." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1732.
Повний текст джерелаАнотація:
Hemimicelles and admicelles are well-investigated wonders in modern science; they are surfactant monolayers and surface adsorbed micelles, respectively. Capacitance measurements for monitoring the formation of dodecyl sulfate (DS) surfactant monolayer on positively charged gold substrates (planar gold) and the adsorbance of 2-naphthol onto DS surfactant monolayer were performed. The investigation of the electrical control of DS at various concentrations (4, 6, 16, and 32 mM) below and above the critical micelle concentration (CMC= 8 mM) on gold surfaces for analyte preconcentration, prior to chromatographic analysis, is presented. Charged ionic surfactants, such as DS, drawn to a surface of opposite charge (porous nickel substrates coated with gold) serve as a stationary phase to trap organic analytes. It is believed that these DS assemblies gain stability through surfactant chain–chain interactions. The attachment and the removal of the surfactant are controlled using an electric field. Due to the fact that the surfactantanalyte association is released by electrical control, organic solvents, which are used in conventional solid phase extraction, are not required, making this procedure environmentally friendly. Electrical Impedance Spectroscopy was used to investigate the formation of the DS layer and the preconcentration of 2-naphthol in the presence of an applied electric field. High performance liquid chromatography was used to determine 2- naphthol concentrations. Anthracene and 9-anthracenecarboxylic acid were substituted as additional test molecules as well. Presented are the results of the preconcentration of 2-naphthol, anthracene and 9-anthracenecarboxylic acid using the DS layer with various concentrations of sodium dodecyl sulfate on a gold electrode surface.
33
Sushko, O. A., О. М. Bilash, and M. M. Rozhitskii. "Nanophotonic method for polycyclic aromatic hydrocarbons detection in water." Thesis, ISE, 2012. http://openarchive.nure.ua/handle/document/8866.
Повний текст джерелаАнотація:
Polycyclic aromatic hydrocarbons (PAHs) are the widespread environmental contaminants that can be found in atmosphere, water, soil, sediment and organisms. Among most dangerous PAHs is benzo[a]pyrene (BP). The effects of BP on health are: short-term when people are exposed to it at levels above the maximum contaminant level (MCL) (0.2 ppm) for relatively short periods of time leading to red blood cells damage, anemia ect; suppression of immune system and long-term, when human beings are exposured do BP influence at levels above the MCL namely effects on reproducibility and high probability of cancer illnesses.
There are known methods for PAHs detection, such as chromatography, immuno-chemistry, biological and chemical ones. However, they have several disadvantages, including high cost, duration and complexity of the analysis procedure, the high detection limit and low selectivity. So at present a development of a new method of PAHs detection based on modern technologies and materials such as nanotechologies and nanomaterials. Belonging to above mentioned is nanophotonic method of PAHs assay.
Nanophotonic method for PAHs detection in particular BP in water is a combination of electrochemical and electrochemiluminescence analysis with the application of nanomaterials and nanotechnologies. This method can be carried out using nanophotonic sensor based on nanomaterials such as semiconductor quantum dots (QDs).
34
Florea, Mara [Verfasser]. "Applications of Fluorescent Displacement-Based Sensors for Monitoring Time-Resolved Changes in Analyte Concentrations / Mara Florea." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037013697/34.
Повний текст джерела
35
Loader, Robert James. "The synthesis of solid phase quenching agents and their applications in derivatisations at low analyte levels." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307321.
Повний текст джерела
36
Kemp, Helen Rochelle. "Sensitive sub-doppler gas phase nonlinear laser spectroscopy for hyperfine structure analysis and trace analyte detection /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3036948.
Повний текст джерела
37
Hoeman, Kurt W. "Novel methods for micellar electro kinetic chromatography and preconcentration on traditional micro fluidic devices and the fabrication and characterization of paper micro fluidic." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2752.
Повний текст джерела
38
Salaam, Jeremy. "Sondes magnetogènes à base de Fe(II) répondantes à un analyte chimique par changement de spin électronique." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEN075.
Повний текст джерелаАнотація:
Cette thèse traite de molécules à base de Fe(II) capables d’un passage de spin sous l’action d’un analyte en solution, utilisées dans le domaine de l’imagerie moléculaire, notamment l’IRM (Imagerie par Résonance Magnétique). Depuis plusieurs années, la communauté scientifique autour de l’IRM a pris conscience de deux problématiques importantes : la faible sensibilité de l’IRM et la toxicité des agents de contrastes utilisés pour l’améliorer. Notre équipe répond à ces deux problématiques en développant des sondes magnétogènes spécifiques à un analyte biologique et supposées moins toxiques. Dans ce but, l’élaboration d’une méthodologie fiable permettant le greffage d’unités sulfonates en périphérie de complexes de coordination, et offrant un gain de solubilité et de compatibilité avec les milieux biologiques, a été réalisé. Puis, elle a été appliquée à un système de sonde déjà établi dans l’équipe afin d’augmenter son pH d’activation. En élargissant ces unités décoratives en périphérie a d’autre fonctions, une série de dérivés a été synthétisé, afin d’en extraire une tendance dans les performances d’activation du système en milieu acide.Dans le but de trouver un système de sonde s’activant à pH physiologique, deux complexes ont été synthétisés, portant des motifs d’activation nouveaux. La caractérisation poussée et l’étude d’activation de ces complexes ont offert de nouvelles données précieuses à équipe dans sa compréhension des concepts moléculaires et leur optimisation.La biocompatibilité in cellulo des systèmes développés a été explorée par l’étude de leur toxicité et de leur pénétration cellulaire. Un projet d’activation enzymatique dans l’estomac de rats, et première tentative de preuve de concept in vivo de l’équipe, a pu être initié. Les manipulations préliminaires s’avèrent prometteuses pour la suite du projet.Enfin, l’écart de signal IRM des objets chimiques synthétisés, écart entre la sonde avant rencontre avec son analyte et après, sont inédits dans le domaine. Ces résultats sont encourageants pour le développement d’une sonde suffisamment sensible pour permettre l’application à des expériences d’imagerie moléculaire de routineThis thesis deals with Fe(II) based molecules capable of a spin switch by interacting with an analyte in solution, which are used in the field of molecular imaging, in particular MRI (Magnetic Resonance Imaging). For several years now, the scientific community around MRI has become aware of two important issues: MRI’s low sensitivity and the toxicity of the contrast agents used to improve it. Our team responds to these two drawbacks by developing magnetogenic probes that are specific to a biological analyte and supposedly less toxic.For that purpose, the development of a reliable methodology allowing the incorporation of sulfonate units on the periphery of coordination complexes, offering a solubility and compatibility increase in biological media, was carried out. Then it was applied to a probe system already established in the team in order to increase its pH of activation. By expanding these peripheral decorative units to other functional groups, a series of derivatives have been synthesized, in order to extract a trend in the activation performance of the system in acidic conditions.With the aim of finding a system operating at physiological pH, two complexes were synthesized, carrying new activation motifs. The extensive characterization and activation studies of these complexes provided valuable data for the team in its understanding and optimization of the probe’s design.The in cellulo biocompatibility of the developed systems has been explored by studying their toxicity and their cellular absorption.An enzymatic activation project in the stomach of laboratory animals (rat), and the team's first in vivo proof of concept attempt, has been initiated. The preliminary manipulations are promising for the rest of the project. Finally, the difference in the MRI signal of the synthesized chemical objects, the difference between the probe before its encounter of the analyte and after, is unprecedented in the field. These results are encouraging for the development of a probe sensitive enough to allow application to routine molecular imaging experiments
39
Shah, Abhilasha Parag. "Impact of Analyte-Surface Spacing on the Performance of Desorption/Ionization on Porous Silicon Mass Spectrometry (DIOS-MS)." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-06302008-131449/.
Повний текст джерелаАнотація:
Desorption/ionization on porous silicon (DIOS), a matrix free-laser desorption mass spectrometric technique shows potential for direct analysis of biological compounds in the low mass region. However, the geometric scale of the porous silicon is significantly smaller than the biological samples used in MS imaging and suspect to limit an effective direct analysis of analyte. Herein, I have investigated the effect of the spacing distance between analytes and a porous substrate in DIOS-MS. In particular, organic polymer films were used to simulate the biological tissue between analyte and porous substrate. These films circumvent biological complexity that simplifies data analysis. The thicknesses of polymer film on the substrate controlled by varying spin coating condition. Different classes of analytes were used as standard molecules to evaluate the analyte-substrate spacing effect. In all cases, the standard molecules were successfully detected atop of the polymer film in DIOS-MS. The insulating layer of polymer shift the laser threshold compare to bare DIOS. Relatively stable signal-to-background (S/B) ratios across the tested spacing distances suggest that the analyte detection is less dependent of the distance between analyte and porous surface. The total ion current (TIC) of the analytes however, decreases as the distance increases suggesting distance effect on desorption/ionization. Moreover, the TIC was limited by the amount of analyte accessible for detection. In addition, the ultra-thin SiOx film showed improvement in analyte detectability over the tested thickness. Analyte detection on the DIOS surface greatly influence by surface chemical functionality; oxidized surface is advantageous for positive mode detection whereas the amine derivatized surface showed improvement in negative mode detection.
40
Zehr, Anna Janina [Verfasser], and Gerhard [Akademischer Betreuer] Binder. "Ermittlung von pädiatrischen Referenzwerten für die Analyte Testosteron, Estradiol und Cortisol (Immunoassay) / Anna Janina Zehr ; Betreuer: Gerhard Binder." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1176510398/34.
Повний текст джерела
41
Moses, Lance. "Fluorescence Imaging of Analyte Profiles in an Inductively Coupled Plasma with Laser Ablation as a Sample Introduction Source." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/4367.
Повний текст джерелаАнотація:
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has risen to among the top tier techniques for the direct analysis of solid samples. However, significant problems remain that must be solved to achieve the full analytical potential of LA-ICP-MS. Inefficient conversion of aerosol to ions within the ICP or transmission through the MS interface may decrease precision, sensitivity, and/or accuracy. Although fundamental mechanisms that govern ion production and transmission have been studied extensively in solution-nebulization (SN) ICP-MS instruments, significant gaps in our understanding remain. Furthermore, it is unclear to what extent differences between the aerosols generated during SN and LA influence either ion production or transmission. In this work, I initially investigated differences in the spatial distributions of Ca, Ba, and Sc ions generated by LA and SN using high-resolution LIF imaging. Ions formed from aerosol generated by LA at low fluence were distributed over much greater axial and narrower radial distances than SN aerosol. Additionally, I investigated the effects of solvent, laser fluence, and ablation atmosphere (He vs Ar) on ion distributions in the ICP. Unlike solvent, changing laser fluence and ablation atmosphere produced considerable changes in the ion signal intensity and spatial distribution during LA. At greater laser fluence, the radial distance over which ions were distributed dramatically increased. Surprisingly, when helium was mixed with argon as carrier gas, ion signals decreased. Many of these effects were assumed to be related to changes in the number and size of particles generated during LA. In a follow-up study, relative contributions to ion densities in the ICP from particles of different sizes were investigated. LIF images were recorded while filtering particles above a threshold size on-line. Micron-sized particles contributed the majority of ions formed in the ICP. For Ba, Ca, and Sc, differences in the axial position where nanometer- and micron-sized particles vaporized were 2, 1, and less than 1 mm, respectively. I also performed experiments to identify changes in the ion signal related to changing ablation conditions vs. changing ICP conditions associated with helium additions to the carrier gas. LIF images were recorded during different combinations of He/Ar added upstream and/or downstream of the ablation cell. Changes in the ion signal during ablation in helium vs argon did not always match expectations based on changes in particle numbers and sizes measured with SEM. The results force re-examination of some of the fundamental assumptions about the effect of carrier gas composition on the performance of LA-ICP-MS. The research described in this dissertation provides valuable insight into fundamental aspects of key ICP processes related to LA generated aerosol.
42
Zehr, Janina [Verfasser], and Gerhard [Akademischer Betreuer] Binder. "Ermittlung von pädiatrischen Referenzwerten für die Analyte Testosteron, Estradiol und Cortisol (Immunoassay) / Anna Janina Zehr ; Betreuer: Gerhard Binder." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1176510398/34.
Повний текст джерела
43
Rathsack, Benjamen Michael. "Photoresist modeling for 365 nm and 257 nm laser photomask lithography and multi-analyte biosensors indexed through shape recognition." Access restricted to users with UT Austin EID, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035170.
Повний текст джерела
44
Zachreson, Matthew R. "Comparing Theory and Experiment for Analyte Transport in the First Vacuum Stage of the Inductively Coupled Plasma Mass Spectrometer." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5610.
Повний текст джерелаАнотація:
The inductively coupled plasma mass spectrometer (ICP-MS) has been used in laboratories for many years. The majority of the improvements to the instrument have been done empirically through trial and error. A few fluid models have been made, which have given a general description of the flow through the mass spectrometer interface. However, due to long mean free path effects and other factors, it is very difficult to simulate the flow details well enough to predict how changing the interface design will change the formation of the ion beam. Towards this end, Spencer et al. developed FENIX, a direct simulation Monte Carlo algorithm capable of modeling this transitional flow through the mass spectrometer interface, the transitional flow from disorganized plasma to focused ion beam. Their previous work describes how FENIX simulates the neutral ion flow. While understanding the argon flow is essential to understanding the ICP-MS, the true goal is to improve its analyte detection capabilities. In this work, we develop a model for adding analyte to FENIX and compare it to previously collected experimental data. We also calculate how much ambipolar fields, plasma sheaths, and electron-ion recombination affect the ion beam formation. We find that behind the sampling interface there is no evidence of turbulent mixing. The behavior of the analyte seems to be described simply by convection and diffusion. Also, ambipolar field effects are small and do not significantly affect ion beam formation between the sampler and skimmer cones. We also find that the plasma sheath that forms around the sampling cone does not significantly affect the analyte flow downstream from the skimmer. However, it does thermally insulate the electrons from the sampling cone, which reduces ion-electron recombination. We also develop a model for electron-ion recombination. By comparing it to experimental data, we find that significant amounts of electron-ion recombination occurs just downstream from the sampling interface.
45
Zachreson, Matthew R. "Comparing Theory and Experiment for Analyte Transport in the First Vacuum Stage of the Inductively Coupled Plasma Mass Spectrometer." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3538.
Повний текст джерелаАнотація:
The Direct Simulation Monte Carlo algorithm as coded in FENIX is used to model the transport of trace ions in the first vacuum stage of the inductively coupled plasma mass spectrometer. Haibin Ma of the Farnsworth group at Brigham Young University measured two radial trace density profiles: one 0.7 mm upstream of the sampling cone and the other 10 mm downstream. We compare simulation results from FENIX with the experimental results. We find that gas dynamic convection and diffusion are unable to account for the experimentally-measured profile changes from upstream to downstream. Including discharge quenching and ambipolar electric fields, however, makes it possible to account for the way the profiles change.
46
Petrich, Nicholas Thomas. "Simulating and explaining passive air sampling rates and analyte air concentrations for semi-volatile compounds on polyurethane foam disks." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3513.
Повний текст джерела
47
Jaeger, Frederick Howard. "Simplified Plant Sample Preparation for use in Gas Chromatography-Mass Spectrometry (GC-MS) Based Metabolomic Profiling and Targeted Analyte Quantitation." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-02202008-155316/.
Повний текст джерелаАнотація:
A simple, fast, reproducible and less laborious sample preparation protocol was developed for the analysis of Arabidopsis thaliana using Gas chromatography coupled with mass spectrometry (GC-MS). In particular, a semi-automated machine tool is used to replace the traditional mortar-pestle method in tissue grinding. One-pot chemical extraction-derivatization is used to provide simplified sample preparation over the conventional multi-step liquid-liquid extraction protocol. Wild-type and transgenic Arabidopsis thaliana seedlings were used as the model system to evaluate performance of this newly developed method for use in metabolic profiling and also targeted quantitative analysis of salicylic acid for the study of systemic acquired resistance.
48
Ghode, Amit Suresh. "Two-Phase Partitioning System Using Elvax 40W Polymer for the Biodegradation of Aqueous Phenols." TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/224.
Повний текст джерелаАнотація:
A solid-liquid two phase partitioning system (TPPS) is a new technology platform for destroying toxic organic compounds. TPPS have traditionally been operated by using an immiscible organic phase which partitions organic compounds into the aqueous phase. TPPS using an immiscible organic phase suffers from several limitations such as the organic phase could be biodegradable and hence only certain compatible microbial strains could be used. This therefore, eliminates the desired use of mixed microbial populations for efficient degradation. A solid-liquid two phase partitioning system, in which solid polymeric beads replace liquid organic phase, appears to have benefits over the traditional liquid-liquid partitioning systems. The choice of suitable polymeric material should have similar absorption properties as the liquid organic solvent but have the added benefit of being able to be used with mixed microbial population. In this study, poly (ethylene-co-vinyl acetate), brand name ELVAX 40W, was selected as the test polymer in an effort to lower the concentrations of selected analytes; phenol, 4- nitrophenol and o-cresol in aqueous solutions. Studies were performed to determine the degree of partitioning using HPLC and UV-VIS. Kinetic studies were also performed and illustrated a first order dependence on the absorption of the phenols tested. Activation energies were also determined for each analyte. Rate constants were on the order of 10-4 min-1. Activation energy ranged from 19-46 kJ/mol.
Regeneration tests showed that a release of analyte from the polymer is possible when the beads are placed in water. Therefore the ability to reuse the polymer is possible and therefore cost efficient. The polymer was observed to lower high concentrations up to 2000 ppm suggesting its potential use to treat the high concentrations of toxic organic compounds.
49
Ghale, Garima [Verfasser], Werner [Akademischer Betreuer] Nau, Mathias [Akademischer Betreuer] Winterhalter, and Andreas [Akademischer Betreuer] Hennig. "Analyte-Responsive Macrocyclic Host-Fluorophore Systems For Monitoring Biological Processes / Garima Ghale. Betreuer: Werner Nau. Gutachter: Werner Nau ; Mathias Winterhalter ; Andreas Hennig." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2014. http://d-nb.info/1087299594/34.
Повний текст джерела
50
Guo, Wenpeng, and 郭文鹏. "Enhancing capabilities of microfluidic chip-capillary devices to extend working range, adjust analyte/sample ratio and improve sample/reagent mixing in biomedical analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46589673.
Повний текст джерела