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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

CHEMOMETRICS, SPECTROMETRY, AND SENSORS FOR INTEGRATED SENSING AND PROCESSING: ADVANCING PROCESS ANALYTICAL TECHNOLOGY

Medendorp, Joseph Peter 01 January 2006 (has links)
The research contained in the following dissertation spans a diverse range of scientific scholarship, including; chemometrics for integrated sensing and processing (ISP), near infrared and acoustic resonance spectrometry for analyte quantification and classification, and an ISP acoustic sensor as an alternative to conventional acoustic spectrometry. These topics may at first seem disjointed; however, closer inspection reveals that chemometrics, spectrometry, and sensors taken together form the umbrella under which applied spectrometry and analytical chemistry fall. The inclusion of each of these three serves to paint the complete portrait of the role of applied spectrometry for the advancement of process analytical technology. To illustrate the totality of this portrait, this research seeks to introduce and substantiate three key claims. (1) When applicable, optical spectrometry and acoustic spectrometry are preferred alternatives to slower and more invasive methods of analysis. (2) Chemometrics can be implemented directly into the physical design of spectrometers, thus sparing the need for computationally demanding post-collection multivariate analyses. (3) Using this principle, ISP sensors can be developed specifically for use in highly applied situations, making possible automatic analyte quantification or classification without the computational burden and extensive data analysis typically associated with conventional spectrometry. More concisely, these three claims can be stated as follows: spectrometry has a broad range of uses, chemometrics for ISP makes spectrometry more efficient, and for all analytical problems with a spectrometric solution, an ISP sensor, specifically tailored to the needs of the experiment, can more effectively solve the same analytical problem.
42

The synthesis and application of near infrared absorbing dyes in photoelectrochemical cells

Goddard, Victoria H. M. January 2006 (has links)
Research into dye sensitised solar cells has increased in recent years as the search for a viable low cost, renewable energy source continues. The synthesis and characterisation of an array of symmetrical and asymmetrical zinc and ruthenium centred phthalocyanines and naphthalocyanines are presented in this work. Certain compounds were designed so that they would possess a carboxylic acid group which could be utilised to chemisorb the compound to a titanium dioxide surface. The dye sensitised titania electrodes were studied as potential photoanodes in dye sensitised solar cells. The use of symmetrical and asymmetrical compounds in the solar cells enabled conclusions to be drawn about the effects on electron injection of the HOMO energy level and the number and position of binding groups. The highest incident photon-to-current conversion efficiency (IPCE) of 4 % and overall conversion efficiency (η) of 0.09 % were obtained when 2,3:9,10-(22,92-carboxyl)benzo(b,k)-15,18,22,25-tetrakis(octyl)phthalocyaninatozinc(II) (63) was utilised as a sensitiser. This response was concluded to be due to the molecule possessing two binding groups and phthalocyanine like energy levels. When the ruthenium centred and zinc centred compounds were compared as sensitisers in DSCs, an increase in photovoltage and photocurrent was observed with the use of the ruthenium centred compounds. This is due to the binding group being attached to the axial ligand and therefore being situated closer to the LUMO electron density which is found at the centre of the molecule. As the binding group is closer there is less hindrance to electron injection into the TiO2 conduction band. Aggregation studies were also conducted on the acid and ester substituted zinc naphthalocyanine with and without the use of additives. It was found that the ester existed primarily as a dimer whose formation is concentration dependent. The acid also existed as a dimer but produced a "fake" monomer peak due to the formation of J aggregates. It was found that upon dilution the angle of the J aggregates shifted so that they formed face-to-face aggregates. It was found that the peripherally binding additive cetyltrimethylammonium bromide (CTAB) prevented aggregation at a concentration 20 times that of the compound but upon dilution rearranged itself so that aggregation was no longer inhibited.
43

Near-infrared spectroscopic studies of human scalp hair in a forensic context

Brandes, Sarina January 2009 (has links)
Human hair is a relatively inert biopolymer and can survive through natural disasters. It is also found as trace evidence at crime scenes. Previous studies by FTIRMicrospectroscopy and – Attenuated Total Reflectance (ATR) successfully showed that hairs can be matched and discriminated on the basis of gender, race and hair treatment, when interpreted by chemometrics. However, these spectroscopic techniques are difficult to operate at- or on-field. On the other hand, some near infrared spectroscopic (NIRS) instruments equipped with an optical probe, are portable and thus, facilitate the on- or at –field measurements for potential application directly at a crime or disaster scene. This thesis is focused on bulk hair samples, which are free of their roots, and thus, independent of potential DNA contribution for identification. It explores the building of a profile of an individual with the use of the NIRS technique on the basis of information on gender, race and treated hair, i.e. variables which can match and discriminate individuals. The complex spectra collected may be compared and interpreted with the use of chemometrics. These methods can then be used as protocol for further investigations. Water is a common substance present at forensic scenes e.g. at home in a bath, in the swimming pool; it is also common outdoors in the sea, river, dam, puddles and especially during DVI incidents at the seashore after a tsunami. For this reason, the matching and discrimination of bulk hair samples after the water immersion treatment was also explored. Through this research, it was found that Near Infrared Spectroscopy, with the use of an optical probe, has successfully matched and discriminated bulk hair samples to build a profile for the possible application to a crime or disaster scene. Through the interpretation of Chemometrics, such characteristics included Gender and Race. A novel approach was to measure the spectra not only in the usual NIR range (4000 – 7500 cm-1) but also in the Visible NIR (7500 – 12800 cm-1). This proved to be particularly useful in exploring the discrimination of differently coloured hair, e.g. naturally coloured, bleached or dyed. The NIR region is sensitive to molecular vibrations of the hair fibre structure as well as that of the dyes and damage from bleaching. But the Visible NIR region preferentially responds to the natural colourants, the melanin, which involves electronic transitions. This approach was shown to provide improved discrimination between dyed and untreated hair. This thesis is an extensive study of the application of NIRS with the aid of chemometrics, for matching and discrimination of bulk human scalp hair. The work not only indicates the strong potential of this technique in this field but also breaks new ground with the exploration of the use of the NIR and Visible NIR ranges for spectral sampling. It also develops methods for measuring spectra from hair which has been immersed in different water media (sea, river and dam)
44

Neural correlates of cognitive workload and anesthetic depth : fNIR spectroscopy investigation in humans /

Izzetoglu, Kurtulus. Onaral, Banu. January 2008 (has links)
Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 60-65).
45

An application of near-infrared spectroscopy for the determination of biomass viability /

Pérez-Clark, Astrid Melisa, January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [158]-162).
46

Infestation detection in wild blueberries using near infrared spectra and multivariate data analysis /

Peshlov, Boyan N., January 2008 (has links)
Thesis (Ph.D.) in Chemical Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 136-147).
47

Chicken egg quality assessment from visible/near infrared observations

Abdel-Nour, Nicolas, January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2009/06/18). Includes bibliographical references.
48

Non-destructive measurement of tomato quality using visible and near-infrared reflectance spectroscopy

Chen, Limei. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2009/06/22). Includes bibliographical references.
49

Functional near infrared spectroscopy in the multimodal assessment of working memory impairments following traumatic brain injury /

Merzagora, Anna Caterina. Izzetoglu, Meltem Alkan. Onaral, Banu. Schultheis, Maria T. January 2010 (has links)
Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 105-116).
50

Near-infrared analysis and process control of pharmaceutical pelletization processes

Wargo, David J. January 2009 (has links)
Thesis (Ph.D.)--Duquesne University, 2009. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 184-195) and index.

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