• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • Tagged with
  • 6
  • 6
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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.
1

Non-destructive Analysis Of Trace Textile Fiber Evidence Via Room-temperature Fluorescence Spectrocopy

Appalaneni, Krishnaveni 01 January 2013 (has links)
Forensic fiber evidence plays an important role in many criminal investigations. Nondestructive techniques that preserve the physical integrity of the fibers for further court examination are highly valuable in forensic science. Non-destructive techniques that can either discriminate between similar fibers or match a known to a questioned fiber - and still preserve the physical integrity of the fibers for further court examination - are highly valuable in forensic science. When fibers cannot be discriminated by non-destructive tests, the next reasonable step is to extract the questioned and known fibers for dye analysis with a more selective technique such as high-performance liquid chromatography (HPLC) and/or gas chromatography-mass spectrometry (GC-MS). The common denominator among chromatographic techniques is to primarily focus on the dyes used to color the fibers and do not investigate other potential discriminating components present on the fiber. Differentiating among commercial dyes with very similar chromatographic behaviors and almost identical absorption spectra and/or fragmentation patterns is a challenging task. This dissertation explores a different aspect of fiber analysis as it focuses on the total fluorescence emission of fibers. In addition to the contribution of the textile dye (or dyes) to the fluorescence spectrum of the fiber, we investigate the contribution of intrinsic fluorescence impurities – i.e. impurities imbedded into the fibers during fabrication of garments - as a reproducible source of fiber comparison. Differentiation of visually indistinguishable fibers is achieved by comparing excitation-emission matrices (EEMs) recorded from single textile fibers with the aid of a commercial spectrofluorimeter coupled to an epi-fluorescence microscope. Statistical data comparison was carried out via principal component analysis. An application of iv this statistical approach is demonstrated using challenging dyes with similarities both in twodimensional absorbance spectra and in three dimensional EEM data. High accuracy of fiber identification was observed in all the cases and no false positive identifications were observed at 99% confidence levels.
2

The "Curtain Dress" : construction, conservation, and analytical research

Villarreal, Nicole 08 November 2012 (has links)
This thesis examines the condition of the “Curtain Dress” of Gone With the Wind (GWTW) with the purpose of advising a conservation plan that would allow its exhibit in 2014 as part of the 75th anniversary of the film. The dress has been stored since 1981 in the Harry Ransom Center (HRC) at the University of Texas at Austin as part of the David O. Selznick (DOS) Collection. The project addresses the book, the film, the creation of the dress, and what happened to it after filming was over. A collaborative team was formed including HRC staff, a conservator, and graduate students from the Textiles and Apparel Division at the University of Texas at Austin. The author of this study provided historical context, document analysis, construction evaluation, and fiber testing. A timeline for the book, film, and garment was established; communications from Selznick referencing the dress were analyzed; construction details were photographed and documented for reference; and colorimetry and spectroscopy techniques were used for fiber analysis. / text
3

An Investigation of Textile Fibers by means of RGB analysis of Birefringence

Feild, Olivia F 01 January 2019 (has links)
Fiber analysis using birefringence has been around for years but has only recently been looked at more closely under a microscope. Recent scientists have proposed methods to correct issues found with fiber analysis using birefringence, yet there has not be a defined perfect method. This research will focus on correcting previously found issues with works by Michel-Lévy and Sorensen's, as well as other scientists involved and perfecting the analysis of fiber through birefringence. The goal will be to take this research one step further into the analysis of textile fibers by RGB value analysis and birefringence. The RGB values will be analyzed in a color analysis program to compare HEX values. The cross section of the fiber will be done to receive an accurate diameter measurement of the fiber. Those RGB values and cross section diameter will then be matched to the Michel-Lévy chart and the birefringence will be determined.
4

Heterologous expression, characterization and applications of carbohydrate active enzymes and binding modules

Kallas, Åsa January 2006 (has links)
Wood and wood products are of great economical and environmental importance, both in Sweden and globally. Biotechnology can be used both for achieving raw material of improved quality and for industrial processes such as biobleaching. Despite the enormous amount of carbon that is fixed as wood, the knowledge about the enzymes involved in the biosynthesis, re-organization and degradation of plant cell walls is relatively limited. In order to exploit enzymes more efficiently or to develop new biotechnological processes, it is crucial to gain a better understanding of the function and mechanism of the enzymes. This work has aimed to increase the knowledge about some of the enzymes putatively involved in the wood forming processes in Populus. Xyloglucan endotransglycosylases and a putative xylanase represent transglycosylating and hydrolytic enzymes, respectively. Carbohydrate binding modules represent non-catalytic modules, which bind to the substrate. Among 24 genes encoding for putative xyloglucan endotransglycosylases or xyloglucan endohydrolases that were identified in the Populus EST database, two were chosen for further studies (PttXTH16-34 and PttXTH16-35). The corresponding proteins, PttXET16-34 and PttXET16-35, were expressed in P. pastoris, purified and biochemically characterized. The importance of the N-glycans was investigated by comparing the recombinant wild-type proteins with their deglycosylated counterparts. In order to obtain the large amounts of PttXET16-34 that were needed for crystallization and development of biotechnological applications, the conditions for the large-scale production of PttXET16-34 in a fermenter were optimized. In microorganisms, endo-(1,4)-β-xylanases are important members of the xylan degrading machinery. These enzymes are also present in plants where they might fulfill a similar, but probably more restrictive function. One putative endo-(1,4)-β-xylanase, denoted PttXYN10A, was identified in the hybrid aspen EST library. Sequence analysis shows that this protein contains three putative carbohydrate-binding modules (CBM) from family 22 in addition to the catalytic module from GH10. Heterologous expression and reverse genetics were applied in order to elucidate the function of the catalytic module as well as the binding modules of PttXYN10A. Just as in microorganisms, some of the carbohydrate active enzymes from plants have one or more CBM attached to the catalytic module. So far, a very limited number of plant CBMs has been biochemically characterized. A detailed bio-informatic analysis of the CBM family 43 revealed interesting modularity patterns. In addition, one CBM43 (CBM43PttGH17_84) from a putative Populus b-(1,3)-glucanase was expressed in E. coli and shown to bind to laminarin (β-(1,3)-glucan), mixed-linked β-(1,3)(1,4)-glucans and crystalline cellulose. Due to their high specificity for different carbohydrates, CBMs can be used as probes for the analysis of plant materials. Generally, they are more specific than both staining techniques and carbohydrate-binding antibodies. We have used cellulose- and mannan binding modules from microorganisms as tools for the analysis of intact fibers as well as processed pulps. / QC 20100903
5

DESIGN AND BEHAVIOR OF COMPOSITE COUPLING BEAM TO COMPOSITE PLATE SHEAR WALL CONNECTIONS

Mubashshir Ahmad (16647003) 01 August 2023 (has links)
<p>Coupled Composite Plate Shear Walls / Concrete Filled (CC-PSW/CFs) are being employed as a seismic lateral force resisting system for the design and construction of mid- to high-rise buildings around the world. The coupled system consists of two or more Composite Plate Shear Walls – Concrete Filled (C-PSW/CFs) connected to each other using composite coupling beams located at the story heights. The CC-PSW/CF system can provide higher overturning moment capacity, lateral stiffness, and ductility than uncoupled walls. Concrete-filled steel box sections are typically used for the composite coupling beams, which are designed to be flexure critical members. When the CC-PSW/CF system is subjected to lateral seismic forces, plastic hinge formation and inelastic deformations (energy dissipation) occur near the ends of most of coupling beams along the structure's height, followed by flexural hinging of the C-PSW/CFs, typically at the base. </p> <p>This work presents the details and design of four composite coupling beam-to-C-PSW/CF connection configurations. Six connection specimens, representing the four connection configurations, with beam clear span-to-section depth, <em>Lb</em>/<em>d</em>, ratios of 3.5 and 5.1, were designed, fabricated, and tested. The experimental program focused on the force-displacement and moment-rotation responses, behavioral observations, limit states, and flexural capacities of the tested specimens. Major limit states and events included yielding of the steel plates comprising the coupling beam, followed by local inelastic buckling, fracture initiation in the base metal (near the weld toes) in the connection region, and fracture propagation through the beam flange and web plates leading to loss of flexural strength and failure. All specimens developed and exceeded the capacity and chord rotation requirements, in accordance with ANSI/AISC 341-22 guidelines.</p> <p>Detailed nonlinear 3D finite element models of the tested specimens were developed and verified using experimental results. The 3D finite element models accurately simulate the stiffness, flexural capacities, and monotonic responses of tested specimens. Nonlinear fiber-based models of the tested coupling beam-to-C-PSW/CF specimens were developed and verified using experimental results. The nonlinear fiber-based models can accurately simulate the stiffness, flexural capacities, and cyclic responses of tested specimens. The benchmarked fiber models were used to estimate the moment-rotation response of full-scale archetype connections. </p>
6

Improved techniques for CE and MALDI-MS including microfluidic hyphenations foranalysis of biomolecules

Jacksén, Johan January 2011 (has links)
In this thesis, improved techniques for biomolecule analysis using capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and hyphenations between those have been presented.A pre-concentration method which is possible to apply in both techniques, has also been investigated. In this work the off-line MS mode has been used either in the form of fractionation (Paper I) or by incorporating the MALDI target in the CE separation system (Paper II).In Paper I, a protocol for CE-MALDI analysis of cyanogen bromide digested bacteriorhodopsin (BR) peptides as model integral membrane protein peptides were established. Also, an improved protocol for partially automated manufacturing of a concentration MALDI-target plate is presented. The design of the targets was suitable for the fractions from the CE. A novel technique for the integration of CE to MALDI-MS using a closed-open-closed system is presented in Paper II, where the open part is a micro canal functioning as a MALDI target window. A protein separation was obtained and detected with MALDI-MS analysis in the micro canal. A method has been developed for detection of monosaccharides originating from hydrolysis of a single wood fiber performed in a micro channel, with an incorporated electromigration pre-concentration step preceding CE analysis in Paper III. The pre-concentration showed to be highly complex due to the fact that several parameters are included that affecting each other. In Paper IV a protocol using enzymatic digestion, MALDI-TOF-MS and CE with laser induced fluorescence (LIF) detection for the investigation of the degree of substitution of fluorescein isothiocyanate (FITC) to bovine serum albumin (BSA), as a contact allergen model system for protein-hapten binding in the skin, is presented. The intention of a further CE-MALDI hyphenation has been considered during the work. In Paper V 2,6-dihydroxyacetophenone (DHAP) was investigated, showing promising MALDI-MS matrix properties for hydrophobic proteins and peptides. 2,5-dihydroxybenzoic acid (DHB) was undoubtedly the better matrix for the hydrophilic proteins, but its performance for the larger and hydrophobic peptides was not optimal. Consequently, DHAP can be used as a compliment matrix for improved analysis of hydrophobic analytes. / QC 20101214

Page generated in 0.0621 seconds