To see the other types of publications on this topic, follow the link: Chemical approach.
Dissertations / Theses on the topic 'Chemical approach'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Chemical approach.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Pennington, Daniel. "Chemical facility preparedness a comprehensive approach." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FPennington.pdf.
Full textAbstract:
Thesis (M.A. in Security Studies (Homeland Security And Defense))--Naval Postgraduate School, September 2006.Thesis Advisor(s): Ted Lewis. "September 2006." Includes bibliographical references (p. 83-88). Also available in print.
2
Aldeeb, Abdulrehman Ahmed. "Systematic approach for chemical reactivity evaluation." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/159.
Full textAbstract:
Under certain conditions, reactive chemicals may proceed into uncontrolled chemical reaction pathways with rapid and significant increases in temperature, pressure, and/or gas evolution. Reactive chemicals have been involved in many industrial incidents, and have harmed people, property, and the environment. Evaluation of reactive chemical hazards is critical to design and operate safer chemical plant processes. Much effort is needed for experimental techniques, mainly calorimetric analysis, to measure thermal reactivity of chemical systems. Studying all the various reaction pathways experimentally however is very expensive and time consuming. Therefore, it is essential to employ simplified screening tools and other methods to reduce the number of experiments and to identify the most energetic pathways. A systematic approach is presented for the evaluation of reactive chemical hazards. This approach is based on a combination of computational methods, correlations, and experimental thermal analysis techniques. The presented approach will help to focus the experimental work to the most hazardous reaction scenarios with a better understanding of the reactive system chemistry. Computational methods are used to predict reaction stoichiometries, thermodynamics, and kinetics, which then are used to exclude thermodynamically infeasible and non-hazardous reaction pathways. Computational methods included: (1) molecular group contribution methods, (2) computational quantum chemistry methods, and (3) correlations based on thermodynamic-energy relationships. The experimental techniques are used to evaluate the most energetic systems for more accurate thermodynamic and kinetics parameters, or to replace inadequate numerical methods. The Reactive System Screening Tool (RSST) and the Automatic Pressure Tracking Adiabatic Calorimeter (APTAC) were employed to evaluate the reactive systems experimentally. The RSST detected exothermic behavior and measured the overall liberated energy. The APTAC simulated near-adiabatic runaway scenarios for more accurate thermodynamic and kinetic parameters. The validity of this approach was investigated through the evaluation of potentially hazardous reactive systems, including decomposition of di-tert-butyl peroxide, copolymerization of styrene-acrylonitrile, and polymerization of 1,3-butadiene.
3
Jensen, Stephanie Meryl, and Stephanie Meryl Jensen. "A Bioorthogonal Approach to Chemical Virology." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621769.
Full textAbstract:
Dengue virus (DENV) is a mosquito-transmitted flavivirus that threatens approximately half of the world's population. In this dissertation, the use of bioorthogonal chemistry as a tool for researching emerging viral diseases, including DENV is explored. To this end, a bioorthogonally-modified amino acid was successfully installed within the proteome of DENV, which was used for the pull down of a known virus-protein interaction. This technology is intended to be broadly used for the determination of any virus-host interaction, through the installment of a non-perturbing modification that 1) does not hinder viral infectivity and 2) can be selectively discriminated by any complimentary probe. En route to using this technology, a new viral purification strategy was developed for DENV that reduces the overall purification time by 10 hours, and improves retention of virion infectivity. This method and a survey of other viral purification methods used with DENV is contained herein. Furthermore, a chemical scaffold that was repurposed for exploration of protein-protein crosslinking, namely for release of a reactive chemical warhead under acidic conditions, was used for the surface modification of DENV. This triazabutadiene probe was found to be activated by light. In this dissertation is reported the first time aryl diazonium ions for protein crosslinking have been generated on a protein or viral surface through UV-irradiation. The advantages and limitations of this chemistry are presented herein.
4
Baldauf, Paul D. "Chemical industry security voluntary or mandatory approach?" Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FBaldauf.pdf.
Full textAbstract:
Thesis (M.A. in Security Studies (Homeland Security and Defense))--Naval Postgraduate School, March 2007.Thesis Advisor(s): Thomas J. Mackin, Nadav Morag. "March 2007." Includes bibliographical references (p. 75-79). Also available in print.
5
Alqahtani, Abdullah. "Integrated approach to chemical process flowsheet synthesis." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/4034.
Full textAbstract:
Chemical process synthesis is an open ended step of process design as it deals with the problem of how to develop and integrate the chemical process flowsheet. Over the past four decades, very few systematic procedures have been proposed for the rigorous synthesis of complete chemical process flowsheets. Mathematical design and heuristics from experience of past processes are the two main methods usually employed in process synthesis. Most approaches for new designs use heuristics based on studying reaction and separation systems in isolation. This thesis discusses the development of a new process synthesis systematic procedure and software that integrates a knowledge based system with Aspen HYSYS process simulator, HYSYS optimizer, Aspen Icarus economic evaluator, and databases, utilising knowledge from existing industrial processes to obtain design rules. The proposed generic superstructure for the synthesis and optimization of reaction-separation-recycle systems has been validated. To account for the non-ideal behaviour of reactors, modular simulation is used and an example of the approach is illustrated for a fluidized bed reactor. Preliminary work in customizing Aspen HYSYS to simulate new unit operation has been illustrated. A Visual Basic for Application (VBA) programming code has been developed to link the integrated knowledge based system (IKBS) to Aspen HYSYS. The prototype IKBS has been applied for the selection of reactor-separator-recycle systems for ethylene oxide, ethylene glycol, acetic acid and cumene manufacturing processes as case studies. A wide range of chemical reactors and separators were considered during the selection process and then elimination occurs at different levels leading to the best alternatives being selected for simulation, optimization and economic evaluation in the second phase of the IKBS for future development. The suggested alternative reactor-separator-recycle systems by the IKBS include currently used processes in addition to novel and recommended reactors/separators in industrial research. The proposed integrated knowledge based approach to chemical process flowsheet synthesis is expected to yield a cost effective design methodology for the petrochemical industry.
6
Milsted, Andrew J. "Facilitating chemical discovery : an e-science approach." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/377591/.
Full textAbstract:
e-Science technologies and tools have been applied to the facilitating of the accumulation, validation, analysis, computation, correlation and dissemination of chemical information and its transformation into accepted chemical knowledge. In this work a number of approaches have been investigated to address the diffeerent issues with recording and preserving the scientific record, mainly the laboratory notebook. The electronic laboratory notebook (ELN) has the potential to replace the paper notebook with a marked-up digital record that can be searched and shared. However it is a challenge to achieve these benefits without losing the usability and flexibility of traditional paper notebooks. Therefore using a blog-based platform will be investigated to try and address the issues associated with the development of a flexible system for recording scientific research.
7
Cocchi, Stefano <1984>. "A chemical loop approach for methanol reforming." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4758/1/Cocchi_Stefano_Tesi.pdf.
Full textAbstract:
Over the past few years, the switch towards renewable sources for energy production is considered as necessary for the future sustainability of the world environment. Hydrogen is one of the most promising energy vectors for the stocking of low density renewable sources such as wind, biomasses and sun. The production of hydrogen by the steam-iron process could be one of the most versatile approaches useful for the employment of different reducing bio-based fuels.
The steam iron process is a two-step chemical looping reaction based (i) on the reduction of an iron-based oxide with an organic compound followed by (ii) a reoxidation of the reduced solid material by water, which lead to the production of hydrogen. The overall reaction is the water oxidation of the organic fuel (gasification or reforming processes) but the inherent separation of the two semireactions allows the production of carbon-free hydrogen.
In this thesis, steam-iron cycle with methanol is proposed and three different oxides with the generic formula AFe2O4 (A=Co,Ni,Fe) are compared in order to understand how the chemical properties and the structural differences can affect the productivity of the overall process. The modifications occurred in used samples are deeply investigated by the analysis of used materials. A specific study on CoFe2O4-based process using both classical and in-situ/ex-situ analysis is reported employing many characterization techniques such as FTIR spectroscopy, TEM, XRD, XPS, BET, TPR and Mössbauer spectroscopy.
8
Cocchi, Stefano <1984>. "A chemical loop approach for methanol reforming." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4758/.
Full textAbstract:
Over the past few years, the switch towards renewable sources for energy production is considered as necessary for the future sustainability of the world environment. Hydrogen is one of the most promising energy vectors for the stocking of low density renewable sources such as wind, biomasses and sun. The production of hydrogen by the steam-iron process could be one of the most versatile approaches useful for the employment of different reducing bio-based fuels.
The steam iron process is a two-step chemical looping reaction based (i) on the reduction of an iron-based oxide with an organic compound followed by (ii) a reoxidation of the reduced solid material by water, which lead to the production of hydrogen. The overall reaction is the water oxidation of the organic fuel (gasification or reforming processes) but the inherent separation of the two semireactions allows the production of carbon-free hydrogen.
In this thesis, steam-iron cycle with methanol is proposed and three different oxides with the generic formula AFe2O4 (A=Co,Ni,Fe) are compared in order to understand how the chemical properties and the structural differences can affect the productivity of the overall process. The modifications occurred in used samples are deeply investigated by the analysis of used materials. A specific study on CoFe2O4-based process using both classical and in-situ/ex-situ analysis is reported employing many characterization techniques such as FTIR spectroscopy, TEM, XRD, XPS, BET, TPR and Mössbauer spectroscopy.
9
Vozniuk, Olena <1989>. "Chemical-Loop Approach in Bio-Alcohols Reforming." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7775/1/Thesis%20Olena%20Vozniuk%202017.pdf.
Full textAbstract:
The current research is focused on the study and evaluation of a new process for the hydrogen generation, named as Chemical-Loop Reforming (CLR) of Ethanol. The main principle of the CLR process is that an oxygen-storage material is first reduced by ethanol stream (T-450oC), and then re-oxidized by water (T-450oC), in order to produce hydrogen and restore the original oxidation state of a looping-material. Different M-modified spinel-type mixed oxides: TYPE I – MFe2O4 and TYPE II – M0.6Fe2.4Oy viz. modified ferrospinels (where M=Cu, Co, Mn, Mg, Ca and Cu/Co, Cu/Mn, Co/Mn), as potentially attractive ionic oxygen and electron carrier looping materials, were prepared via co-precipitation method and tested in terms of both redox properties and catalytic activity to generate hydrogen by oxidation with steam, after the reductive step carried out with ethanol. Particularly, the focus on the reactivity behavior of binary/ternary materials explained by their ability to form thermodynamically stable spinel oxides which allow us to re-obtain the initial spinel phase upon cycling and in turn increase a stability of the looping material itself. In addition, the research includes in-situ DRIFTS and in-situ XPS studies that allowed to extract information at molecular level and to follow surface changes within the reduction/re-oxidation processes during CLR process. Bulk characterizations have been done using XRD, TEM/SEM/EDX, TPR/O, Magnetic measurements and Raman/Mössbauer Spectroscopic techniques. Moreover, a modification of the conventional CLR process with an addition of the 3rd regeneration step (carried out with air) was done in order to increase the stability of the looping material and to overcome the deactivation problems, such as: a coke deposition/accumulation and an incomplete re-oxidation of M0 during the 2nd step.
10
Heikkilä, Anna-Mari. "Inherent safety in process plant design : an index-based approach /." Espoo [Finland] : Technical Research Centre of Finland, 1999. http://www.vtt.fi/inf/pdf/publications/1999/P384.pdf.
Full text
11
Delacour, Quentin. "Light-induced protein degradation : a chemical biology approach." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066347/document.
Full textAbstract:
La régulation de la protéolyse est un outil efficace pour le contrôle de la fonction d'une protéine dans des cellules. Nous présentons dans ce travail une stratégie générique permettant d'activer la protéolyse de façon conditionnelle par la lumière, améliorant ainsi la résolution spatio-temporelle. Notre approche repose sur un système de dégradation inductible par l'auxine (AID), mis au point en transposant des composants de la voie de dégradation contrôlée par l'auxine existant chez les plantes dans des cellules de mammifères. Nous présentons une version optimisée du système AID qui a permis de diminuer de façon significative la stabilité de protéines cibles en présence d'auxine. Nous avons en parallèle développé un déclencheur de dégradation photo-activable sous la forme d'une auxine cagée. Une illumination courte et locale permet la libération efficace de l'auxine dans les cellules et induit la dégradation de protéine d'intérêt avec un bon contrôle spatiotemporel. Cette méthode générique a été utilisée dans des contextes nucléaires et cytoplasmiquesThe regulation of proteolysis is an efficient way to control protein function in cells. Here, we present a general strategy enabling to increase the spatiotemporal resolution of conditional proteolysis by using light activation as trigger. Our approach relies on the auxin-inducible degradation (AID) system obtained by transposing components of the plant auxin-dependent degradation pathway in mammalian cells. We developed an optimized version of the AID which enables to significantly destabilize target proteins in presence of auxin. Parallely, we developed a photoactivatable auxin that acts as a photoactivatable inducer of degradation. Upon local and short light illumination, auxin is released in cells and triggers the degradation of a protein of interest with spatiotemporal control. This generic method was implemented in nuclear and cytoplasmic contexts
12
Horne, Simon James. "A novel hybrid approach to modeling chemical processes." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531756.
Full text
13
Valette, Nathalie Marie. "A chemical biology approach to investigate amyloid formation." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555842.
Full textAbstract:
Many peptides and proteins have now been linked with 'amyloidosis' disorders despite having apparently different structural and functional properties in their native states. Although progress has been made over recent years, it is still unclear how such different proteins can assemble into the common type of cross-B architecture that characterises such aggregates. Detailed knowledge of the mechanism leading to protein misfolding and aggregation, and of the structures of amyloid fibrils is highly important in order to develop new drugs capable of treating these life-threatening diseases. In addition such studies will illuminate the fundamental principles underpinning the behaviour of the peptide chain. Using a chemical approach, modifications that are generally difficult to access with standard biological techniques can be easily introduced into the polypeptide chain. These chemical modifications which can include completely unnatural functionalities can allow site-specific interactions to be studied during fibrillar assembly, and provide a deeper understanding of the underlying causes of aggregation at both peptide and protein scale. In this work we show how the aggregation of a peptide corresponding to strand E of P2-microglobulin can be modulated by phosphorylation. Peptides equivalent to strand E were synthesised with inclusion of phosphoamino acids. By monitoring the aggregation propensity of an array of differentially phosphorylated sequences at a range of pH values, the effect of the phosphate group was determined. Not only was the aggregation pH-dependent, but also the position of the phosphate group in the peptide sequence was important for the propensity of the peptide to aggregate. These results were combined with molecular dynamics simulations to produce models of putative fibrillar architectures. Because small peptide model systems cannot always mimic the aggregation behaviour of the equivalent full-length protein, a synthetic strategy to chemically prepare full-length P2M was developed with the scope to introduce non-natural amino acids and to probe the effect of those on the aggregation propensity of P2M. A four fragment strategy previously developed in the group with a single point mutation at Ser52 and a phosphotyrosine residue at position 67 was optimised and enhanced, and the conditions to achieve the final folding and oxidation steps were determined. A synthetic route to prepare a true wild-type P2M requiring a 55-amino acid long peptide fragment was also developed.
14
Toole, Edward. "An expert system approach to chemical hazard assessment." Thesis, Glasgow Caledonian University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319147.
Full textAbstract:
Hazard assessment involves the retrieval of appropriate chemical hazard data and the production of an assessment which complies with relevant regulations. This is a complex process requiring detailed knowledge of chemical hazards and hazard assessment regulations. The purpose of this project is to investigate the use of an expert system approach for hazard assessment of complex systems. The approach has focused on the design, development and evaluation of an expert hazard assessor after appropriate modelling of chemical database retrieval, and legislative knowledge base. An "intelligent form" was designed to link the legislation to the chemical hazard data. To facilitate ease of use, the program was extended to include an on-line help facility, and a user friendly interface to address local and remote databases. The feasibility and benefits of the Expert Hazard Assessor ( EHA ) have been demonstrated through system testing and evaluation using sample regulations, and available chemical data, by groups of inexperienced users. Comparison with a previous standard expert system, also shows the EHA to be more comprehensive in output, more efficient, easier to use for the non-expert assessor, and provides better help support. The results suggest that an EHA such as the one detailed in this work is of significant benefit in providing appropriate hazard assessment.
15
Byrne, Paul E. "A new approach to chemical synthesis of glycopeptides." Thesis, Liverpool John Moores University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304508.
Full text
16
Fishovitz, Jennifer. "A Chemical Approach to Distinguish ATP-dependent Proteases." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1291142553.
Full text
17
Radisic, Milica. "Biomimetic approach to cardiac tissue engineering." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28665.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2004."September 2004."
Includes bibliographical references.
(cont.) biochemical and morphological properties in the pretreated group. Finally, in order to mimic capillary structure cardiac fibroblasts and myocytes were co-cultured on a scaffold with a parallel channel array that was perfused with culture medium supplemented with synthetic oxygen carrier (PFC emulsion). Presence of the PFC emulsion resulted in significantly higher cell density and improved contractile properties compared to the constructs cultivated in the culture medium alone, by increasing total oxygen content and effective diffusivity.
Heart disease is the leading cause of death in the Western world. Tissue engineering may offer alternative treatment options or suitable models for studies of normal and pathological cardiac tissue function in vitro. Current tissue engineering approaches have been limited by diffusional oxygen supply, lack of physical stimuli and absence of multiple cell types characteristic of the native myocardium. We hypothesized that functional, clinically sized (1-5 mm thick), compact cardiac constructs with physiologic cell densities can be engineered in vitro by mimicking cell microenvironment present in the native myocardium in vivo. Since cardiac myocytes have limited ability to proliferate we developed methods of seeding cells at high densities while maintaining cell viability. Cultivation of cardiac constructs in the presence of convective-diffusive oxygen transport in perfusion bioreactors, maintained aerobic cell metabolism, viability and uniform distribution of cells expressing cardiac markers. To improve cell morphology and tissue assembly cardiac constructs were cultivated with electrical stimulation of contraction in a physiologically relevant regime. Electrical stimulation enabled formation of tissue with elongated cells aligned in parallel and with organized ultrastructure remarkably similar to the one present in the native heart. To investigate the effect of multiple cell types on the properties of engineered cardiac tissue cardiac fibroblasts and cardiac myocytes were cultivated synchronously, separately or serially (pretreatment of scaffolds with fibroblasts followed by the addition of myocytes). Presence of fibroblasts remarkably improved contractile response of the engineered cardiac constructs with the superior
by Milica Radisic.
Ph.D.
18
Wood, Mark D. "A Methodological Approach to Process Intensification." Thesis, Cranfield University, 2000. http://hdl.handle.net/1826/3560.
Full textAbstract:
A methodological approach to process intensification (PI) has been developed to aid in
the design of intensified chemical processes. Current process development procedures
fail to consider if, and how, a chemical process can be intensified, resulting in limited
application of PI in the chemicals industry. The PI methodology has been developed
to meet these needs, focusing upon the chemical reaction stages of a process.
The PI methodology is a paper-based tool, based around a flowsheet known as the
framework. Throughout development, the methodology was applied to industrial case
studies which revealed considerations that should be included in the methodology and
aided in determining its format. Each section of the framework contains checklists and
procedures detailing the information required and the decisions to be made by the
participants, who should be in a multi-disciplinary team. Examination of chemical
reaction kinetics and the effects of mixing upon the reaction are key aspects of the
methodology that are normally not examined during process development.
Incorporated within the methodology is a PI experimental protocol designed to model
PI operation in the laboratory. Mixing theory was reviewed to identify that the protocol
approach should be based upon recreating the mixing conditions experienced in a full
scale plant within a small scale laboratory stirred vessel.
The developed laboratory protocol utilises semi-batch operation in a highly-mixed
stirred vessel of 10cm diameter and height with twin pitched-blade turbine impellers.
Turbulent energy dissipation rates of 150 W/kg can be achieved in the vessel.
Experiments were run, showing that the performance of static mixer reactors can be
predicted through the application of the protocol, though future work is required to
develop this laboratory protocol approach into a rigorous experimental tool.
19
Prapainop, Kanlaya. "A chemical approach to nanoparticle targeting of the macrophage." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549608.
Full text
20
Alshami, Ali Saleh. "Dielectric properties of biological materials : a physical-chemical approach." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/A_Alshami_053107.pdf.
Full text
21
Nortcliffe, Anne. "Anti-logging approach to pH control of chemical effluent." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398382.
Full text
22
Pookaiyaudom, Panavy. "Chemical current-conveyor : a new approach in biochemical computation." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7037.
Full textAbstract:
Biochemical sensors that are low cost, small in size and compatible with integrated circuit technology play an essential part in the drive towards personalised healthcare and the research described in this thesis is concerned with this area of medical instrumentation. A new biochemical measurement system able to sense key properties of biochemical fluids is presented. This new integrated circuit biochemical sensor, called the Chemical Current-Conveyor, uses the ion sensitive field effect transistor as the input sensor combined with the current-conveyor, an analog building-block, to produce a range of measurement systems. The concept of the Chemical Current-Conveyor is presented together with the design and subsequent fabrication of a demonstrator integrated circuit built on conventional 0.35μm CMOS silicon technology. The silicon area of the Chemical Current-Conveyor is (92μm x 172μm) for the N-channel version and (99μm x 165μm) for the P-channel version. Power consumption for the N-channel version is 30μW and 43μW for the P-channel version with a full load of 1MΩ. The maximum sensitivity achieved for pH measurement was 46mV per pH. The potential of the Chemical Current Conveyor as a versatile biochemical integrated circuit, able to produce output information in an appropriate form for direct clinical use has been confirmed by applications including measurement of (i) pH, (ii) buffer index ( ), (iii) urea, (iv) creatinine and (v) urea:creatinine ratio. In all five cases the device has been demonstrated successfully, confirming the validity of the original aim of this research project, namely to produce a versatile and flexible analog circuit for many biochemical measurement applications. Finally, the thesis closes with discussion of another potential application area for the Chemical Current Conveyor and the main contributions can be summarised by the design and development of the first: ISFET based current-conveyor biochemical sensor, called 'Chemical Current Conveyor, CCCII+' has been designed and developed. It is a general purpose biochemical analog building-block for several biochemical measurements. Real-time buffer capacity measurement system, based on the CCCII+, which exploits the imbedded analog computation capability of the CCCII+. Real-time enzyme based CCCII+ namely, Creatinine-CCCII+ and Urea-CCCII+ for real-time monitoring system of renal system. The system can provide outputs of 3 important parameters of the renal system, namely (i) urea concentration, (ii) creatinine concentration, and (ii) urea to creatinine ratio.
23
Amale, Amit. "New approach to the design and optimization on energy efficient chemical processes /." View online ; access limited to URI, 2008. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3314439.
Full text
24
De, Man Patrick A. P. (Patrick Antonius Petrus). "Applications of the Bayesian approach for experimentation and estimation." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34624.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.Page 272 blank.
Includes bibliographical references (p. 267-271).
A Bayesian framework for systematic data collection and parameter estimation is proposed to aid experimentalists in effectively generating and interpreting data. The four stages of the Bayesian framework are: system description, system analysis, experimentation, and estimation. System description consists of specifying the system under investigation and collecting available information for the parameter estimation. Subsequently, system analysis entails a more in-depth system study by implementing various mathematical tools such as an observability and sensitivity analysis. The third stage in the framework is experimentation, consisting of experimental design, system calibration, and performing actual experiments. Finally, the last stage is estimation, where all relevant information and collected data is used for estimating the desired quantities. The Bayesian approach embedded within this framework provides a versatile, robust, and unified methodology allowing for consistent incorporation and propagation of uncertainty. To demonstrate the benefits, the Bayesian framework was applied to two different case studies of complex reaction engineering problems.
(cont.) The first case study involved the estimation of a kinetic rate parameter in a system of coupled chemical reactions involving the relaxation of the reactive O(D) oxygen atom. The second case study was aimed at estimating multiple kinetic rate parameters concurrently to gain an understanding regarding the reaction mechanism of the oxygen addition to the transient cyclohexadienyl radical. An important advantage of the proposed Bayesian framework demonstrated with these case studies is the possibility of 'real-time' updating of the state of knowledge regarding the parameter estimate allowing for exploitation of the close relationship between experimentation and estimation. This led to identifying systematic errors among experiments and devising a stopping rule for experimentation based on incremental information gain per experiment. Additional advantages were the improved understanding of the underlying reaction mechanism, identification of experimental outliers, and more precisely estimated parameters.
(cont.) A unique feature of this work is the use of Markov Chain Monte Carlo simulations to overcome the computational problems affecting previous applications of the Bayesian approach to complex engineering problems. Traditional restricting assumptions can therefore be relaxed so that the case studies could involve non-Gaussian distributions, applied to multi-dimensional, nonlinear systems.
by Patrick A.P. de Man.
Ph.D.
25
Bahri, Parisa A. "A new integrated approach for operability analysis of chemical plants." Connect to full text, 1995. http://hdl.handle.net/2123/4015.
Full textAbstract:
Thesis (Ph. D.)--University of Sydney, 1996.Title from title screen (viewed on February 3, 2009) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Dept. of Chemical Engineering. Degree awarded 1996, thesis submitted 1995. Includes bibliographical references. Also issued in print.
26
Jiang, Jun. "A generalized quantum chemical approach for nano- and bio-electronics." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286.
Full text
27
Schellenberger, Mario [Verfasser], and Brunhilde [Akademischer Betreuer] Blömeke. "Immunoprophylactic approach against chemical carcinogensis / Mario Schellenberger ; Betreuer: Brunhilde Blömeke." Trier : Universität Trier, 2012. http://d-nb.info/119780630X/34.
Full text
28
Shiers, Vincent Paul. "Surface chemical physics of dye- diacetyl interactions : an optical approach." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358231.
Full text
29
Sadawi, Noureddin. "A rule-based approach for recognition of chemical structure diagrams." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4325/.
Full textAbstract:
In chemical literature much information is given in the form of diagrams depicting chemical structures. In order to access this information electronically, diagrams have to be recognized and translated into a processable format. Although a number of approaches have been proposed for the recognition of molecule diagrams in the literature, they traditionally employ procedural methods with limited flexibility and extensibility. This thesis presents a novel approach that models the principal recognition steps for molecule diagrams in a strictly rule based system. We develop a framework that enables the definition of a set of rules for the recognition of different bond types and arrangements as well as for resolving possible ambiguities. This allows us to view the diagram recognition problem as a process of rewriting an initial set of geometric artefacts into a graph representation of a chemical diagram without the need to adhere to a rigid procedure. We demonstrate the flexibility of the approach by extending it to capture new bond types and compositions. In experimental evaluation we can show that an implementation of our approach outperforms the currently available leading open source system. Finally, we discuss how our framework could be applied to other automatic diagram recognition tasks.
30
Hanson, Kimberley. "A chemical genetic approach to identify new treatments for melanoma." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/57211/.
Full textAbstract:
Melanoma is the most deadly form of skin cancer which develops from the pigment producing cells called melanocytes. Unlike the majority of other cancers, the incidence rates of melanoma are still on the rise and the few treatment options currently available are being hindered by resistance. A recent chemical genetic screen carried out in Xenopus laevis embryos identified that the already FDA approved drug leflunomide used for rheumatoid arthritis patients also holds potential therapeutic value in treating melanoma. This thesis shows the results of a new successful chemical genetic and cell based viability screen of the NCI Diversity set II library. 13 potential novel targets for treating melanoma were identified. This thesis also further characterised the function of leflunomide and showed that leflunomide reduces the number of viable cells in both wild type and BRAFV600E mutant melanoma cell lines. Further experiments revealed leflunomide reduces cell proliferation and causes cells to arrest in G1 of the cell cycle. Cell death assays showed leflunomide to cause apoptosis coupled with a stable mitochondrial membrane potential at 25 and 50μM leflunomide. However at 100μM the number of apoptotic cells decreased and an increase in the number of viable cells with a hyperpolarised mitochondrial membrane potential was observed. To determine if leflunomide had the potential to be used in combination with other melanoma drugs, it was tested in combination with the MEK inhibitor selumetinib. This combination showed a synergistic effect in the majority of the cell lines tested. The M375 melanoma cell line produced strong synergy values across all of the combinations of leflunomide and selumetinib tested. This combination led to an enhanced decrease in tumour size when tested in vivo in a mouse xenograft model when compared to either drug alone. Key words; Melanoma, BRAFV600E, leflunomide, cell viability, selumetinib, synergy, combination index value, NCI Diversity Set II, Xenopus laevis.
31
Vafaeyan, Shadi. "A new approach to the Rough Set multicriteria optimisation method." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/28031.
Full textAbstract:
In the recent years, enormous amount of attention has been given to multicriteria optimisation problems. These are problems with conflicting objectives, to which it is impossible to obtain an optimum solution that contains the best value for every criterion simultaneously, therefore the decision maker must decide on a reasonable compromise. There have been numerous developments of optimisation methods to aid the decision-maker in addressing such problems. These methods can be divided to two categories based on the use or not of the Pareto domain (PD). The Pareto domain is the set of all non-dominated solutions to the multicriteria problem, where no solution is better or worse than any other in the set when all the criteria are considered equal in importance.
This thesis is a collection of two papers that focuses on a new approach to the Rough Set multicriteria optimisation technique. Rough Set method (RSM) requires the determination of the PD as the first step to the optimisation process. In the suggested new approach to RSM, a more systematic way in the selection of points from the PD, that is given to the expert for ranking and then the generation of rules by which the entire PD is ranked, is presented. The RSM that operates based on this new approach was applied to three case studies in paper 1 and to "Beer quality optimisation" in the second paper. The results were compared to the ones obtained by the traditional RSM, Net Flow method and the simple Least Squares method. In conclusion, the new RSM showed to be the most reliable and robust method of all.
32
Arizzi, Simone Marco Paolo. "Diffusion of small molecules in polymeric glasses : a modelling approach." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13742.
Full text
33
How, Bing Shen. "Novel sustainable evaluation approach for multi-biomass supply chain." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49091/.
Full textAbstract:
After the oil crisis held in 1973 and 1979, academicians and industry players have noticed the importance and necessity of having alternative and sustainable energy sources in future. Biological wastes, also named as “Biomass” has been cited as one of the significant sustainable energy sources. Biomass poses an ideal and substantial potential to achieve a sustainable system. However, the development of biomass industry is still relatively sluggish due to the lack of confidence of the investor to venture in this relatively new green business. This is most probably attributed to the low-maturation of biomass technologies compared to other conventional technologies, high logistics cost required for biomass transportation and uncertain market penetration barrier for the biomass-derived products. This raises the importance of having a proper biomass management system and a systematic evaluation approach to assess the sustainability performances of the biomass industry. Therefore, the ultimate goal of this thesis is to develop a sustainable multi-biomass supply chain with the aims of optimising all three sustainability dimensions simultaneously. A sustainable multi-biomass supply chain is referred as the integrated value chain of the green products, which derived from various types of biomass, starting from harvesting stage to the final products delivery stage. This thesis discusses in detail on the relevant previous research works toward the introduction of novel evaluation approach to attain different sustainable objectives (i.e., economic, environmental and social) simultaneously. The evaluation approach encompasses various components, including (i) model reduction by using P-graph integrated two-stage optimisation approach; (ii) consideration of vehicle capacity constraint for detailed transportation cost estimation; (iii) integration of various sustainability indexes using various optimisation techniques. On top of that, two novel debottlenecking approaches, one through principal component analysis (PCA) method; while another through P-graph framework, which able to identify and remove barriers that limit the sustainability performance of the biomass supply chain, are proposed. Aside from this, this thesis also aims to reduce the gaps between the researchers and industry players by developing some user-friendly and non-programming-background dependent decision-making tools. Thus, decision-makers are able to understand the insight of their problems easily without requirement of strong mathematical background. A case study in Johor, a southern state in Malaysia, which is endowed with extensive biomass resources, is used to demonstrate the effective of the proposed approaches.
34
Selvaraj, Rajkumar. "Plant-wide energy assessment using a systems approach." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3125.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains vi, 97 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 97).
35
Godin, François. "Theory and simulation of self-cycling fermentation : a population balance approach." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0006/MQ44012.pdf.
Full text
36
Keibler, Mark Andrew. "An integrated approach to understanding the metabolic rewiring of cancer cells." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115016.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references.
Cancer remains a leading worldwide health problem, and in the U.S., 1 in 3 women and 1 in 2 men are expected to develop it during their lifetimes. While the last several decades have provided tremendous understanding of the genetic mutations and signaling pathways that give rise to oncogenic transformation. However, the field of oncology has only relatively recently begun to appreciate the extent of metabolic rewiring required to sustain the uncontrolled growth of tumors. Cancer metabolism is now an active area of research, and efforts are underway to expand the range of oncology diagnostics and therapeutics through targeting metabolism. Despite this progress, there remains much unknown about the extent of metabolic remodeling in cancer cells, including the influence of proliferation, oncogene activation, tumor suppressor loss, tissue of origin, metastatic potential, environmental cues, and many other factors. Further, metabolism comprises a large and complex network of interconnected reactions and transport processes that interface with many other components of cell physiology. In the field of metabolic engineering, there is precedence for using systems-wide approaches to studying metabolism, and these can be applied to cancer cells to unravel the contribution of such factors to the metabolic phenotype. In this thesis, we describe an integrated approach, spanning multiple computational and empirical techniques derived from metabolic engineering, to understand contributors to cancer metabolism. We specifically focused on the influence of proliferation (i.e. cell growth and division) for our analysis. We first review how some of the techniques of metabolic engineering, most notably stable isotope tracers, can be used to study metabolism in cancer cells. Next, using a published account of hybridoma composition, we analyzed the metabolic requirements of proliferation through reducing mammalian cell biomass needs to a small number of precursors and cofactors. We then incorporated this information into a stoichiometric network to understand how metabolic flux became redistributed following either shifts in metabolic objective or the introduction of constraints to simulate respiratory impairment. These investigations revealed the high biosynthetic burdens of amino acids, ATP, and NADPH, but also demonstrated the flexibility through which metabolism can adapt to fulfill these needs. Finally, we established a cell line system to study the differential metabolic effects of proliferation and expression of an oncogenic mutant of KRAS that drives growth factor-independent division. We found that, in the growth-titratable control cell line, proliferation was accompanied by a dramatic switch of branched-chain amino acid catabolism for TCA cycle flux to proteinogenesis. Additionally, we saw that cells undergoing oncogenic KRAS-driven growth possessed lower consumption rates of the major carbon metabolic substrates, glucose and glutamine, than the growth factor-sensitive control line growing at comparable rates. Our multifaceted approach toward understanding the influence of proliferation on metabolism in cancer cells clarifies the biosynthetic requirements for growth and range of metabolic strategies through which they can be satisfied. As well, our comparison of growth vs. oncogenic KRAS-driven metabolism represents, to our knowledge, the first rigorous attempt to deconvolute the proliferation- and oncogene-specific effects on metabolism in a cell line model.
by Mark Andrew Keibler.
Ph. D.
37
Tan, Jonathan S. (Jonathan Samuel). "A quantitative approach for continuous improvement in process safety and reliability." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/10793.
Full text
38
Huang, Kuan-Chen. "Study The Application of Non-isocyanate Approach in Polyurethanes and Diols." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron161729301625948.
Full text
39
Ross, Roderick. "Dynamic operability assessment : a mathematical programming approach based on Q-parametrization." Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/19814.
Full textAbstract:
Bibliography: pages 197-208.The ability of a process plant to guarantee high product quality, in terms of low variability, is emerging as a defining feature when distinguishing between alternative suppliers. The extent to which this can be achieved is termed a plant's dynamic operability and is a function of both the plant design and the control system design. In the limit, however, the closedloop performance is determined by the properties inherent in the plant. This realization of the interrelationship between a plant design and its achievable closed-loop performance has motivated research toward systematic techniques for screening inherently inferior designs. Pioneering research in the early 1980's identified right-half-plane transmission zeros, time delays, input constraints and model uncertainty as factors that limit the achievable closedloop performance of a process. Quantifying the performance-limiting effect of combinations of these factors has proven to be a challenging problem, as reflected in the literature. It is the aim of this thesis to develop a systematic procedure for dynamic operability assessment in the presence of combinations of performance-limiting factors. The approach adopted in this thesis is based on the Q-parametrization of stabilizing linear feedback controllers and involves posing dynamic operability assessment as a mathematical programming problet? In the proposed formulation, a convex objective function, reflecting a measure of closed-loop performance, is optimized over all stable Q, subject. to a set of constraints on the closed-loop behavior, which for many specifications of interest is convex. A discrete-time formulation is chosen so as to allow for the convenient hand.ling of time delays and time-domain constraints. An important feature of the approach is that, due to the convexity, global optimality is guaranteed. Furthermore, the fact that Q parametrizes all stabilizing linear feedback controllers implies that the performance at the optimum represents the best possible performance for any such controller. The results are thus not biased by controller type or tuning, apart from the requirement that the controller be linear.
40
Ashner, Matthew N. (Matthew Nickol). "Data-driven approach to understanding exciton-exciton interactions in CsPbBr₃ nanocrystals." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122847.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 105-109).
Lead halide perovskites are a rapidly developing class of materials of interest for optoelectronic applications. They have a number of desirable properties such as long carrier diffusion lengths and defect tolerance that arise from the materials' unique dielectric properties. Although much of the initial interest in lead halide perovskites was geared towards producing highly efficient solar cells from the bulk material, cubic perovskite nanocrystals are a strong candidate system for light-emitting applications. Optical gain in semiconductor nanocrystals relies on emission from biexciton or doubly excited states. Knowledge of the spectral properties of biexciton states is critical for understanding optical gain development as well as many-body interactions between charge carriers more broadly. In this thesis, we develop and demonstrate a data-driven approach to characterizing the energetics and dynamics of biexciton states in CsPbBr₃ nanocrystals using TA spectroscopy.
We then use the understanding developed using the TA data to guide experiments using other techniques and further examine the physical phenomena that influence these excited states. In Chapter 2, we describe our data-driven method in detail and demonstrate its effectiveness in extracting spectral information about CsPbBr₃ nanocrystals. The method combines the target analysis fit commonly employed in organic systems with Bayesian inference and a Markov chain Monte Carlo sampler to accurately characterize the model uncertainty and vet the model itself. In Chapter 3, we apply the analysis developed in Chapter 2 to a size-series of CsPbBr₃ nanocrystals to extract the biexciton and exciton component TA spectra as a function of nanocrystal size. We find that the exciton and biexciton spectra have distinctive shapes, in contrast with the common assumption about these spectra.
The biexciton spectra a broader and slightly blue-shifted from the exciton spectrum, and the broadening and blue-shifting both increase as the nanocrystal size decreases. We verify this with our own time-resolved photoluminescence experiments. In Chapter 4, we propose and discuss in detail the development of an experiment to verify our hypothesis for why the exciton-exciton interaction is repulsive - the effect of polaron formation. We describe the development of a femtosecond stimulated Raman spectroscopy experiment to directly observe polaron formation and the challenges of performing this technique at high repetition rate. The central goal of this thesis is to describe a more careful approach to analyzing spectroscopic data.
by Matthew N. Ashner.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering
41
Linh, Thi Thuy Vu. "An integrated approach for simultaneous operability and switchability analysis of chemical plants." Phd thesis, Department of Chemical Engineering, 1999. http://hdl.handle.net/2123/3968.
Full text
42
Magee, Alfred Wesley. "Chemical surface textures on quartz grains : an experimental approach using salts." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306038.
Full text
43
Georget, Dominique M. R. "A physical and chemical approach to understanding texture in Daucus carota." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302024.
Full text
44
Lucius, Ruth A. "Assessing Corn Quality And Transformation During Nixtamalization: A Physico-Chemical Approach." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1231442056.
Full text
45
Martínez, Haya Rebeca. "Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/114828.
Full textAbstract:
En las últimas décadas, los procesos redox fotoinducidos mediados por luz visible han recibido gran atención debido a las suaves condiciones de operación en que se llevan a cabo. Como resultado, se han logrado posicionar como una alternativa más dentro de los Procesos de Oxidación Avanzada. Además, se han convertido en una metodología excepcional en síntesis orgánica, que ha abierto la puerta a nuevas rutas químicas con aplicaciones sintéticas. Sin embargo, a pesar del crecimiento del campo, se ha prestado poca atención a los mecanismos por los que operan estos procesos.
El principal objetivo de esta tesis fue avanzar en la comprensión de distintos procesos fotoredox llevados a cabo empleando fotocatalizadores orgánicos. Más específicamente, se estudió la viabilidad de distintos fotocatalizadores orgánicos, y además, se realizó un estudio mecanístico detallado basado en técnicas resueltas en el tiempo. A partir de estos resultados, se estableció una metodología para determinar los puntos clave a considerar en un sistema fotoredox.
En primer lugar, en la Parte I, se eligieron dos fotocatalizadores basados en sales de pirilio y tiapirilio, que operan mediante transferencia electrónica oxidativa, con distintos objetivos. En el Capítulo 3, se evaluó su aplicabilidad en la fotodegradación de dos contaminantes de la industria del corcho y se estudió el mecanismo por el que se produce dicha fotodegradación. En el Capítulo 4, se demostró la utilidad de la detección directa de todos los intermedios de vida corta derivados del TPP+ implicados en la oxidación fotocatalizada como herramienta para evaluar el nivel de fotodegradación. En el Capítulo 5, se empleó TPTP+ para establecer las mejores características de un fotocatalizador y la influencia de la concentración de las sustancias a oxidar en la eficiencia de los estados excitados, o en general, de los intermedios clave de vida corta.
En segundo lugar, en la Parte II, en el Capítulo 6, se evaluó el potencial del Rosa Bengala en la eliminación de dos fármacos. Éste es un fotocatalizador típico en la remediación de aguas residuales conocido por actuar via mecanismo Tipo II. Se incluyó además un segundo fotocatalizador, Perinaftenona, cuyo rendimiento cuántico de oxígeno singlete es incluso mayor a Rosa Bengala. En el Capítulo 7, se llevó a cabo la fotooxidación de tres contaminantes, usando NMQ+, un fotocatalizador inusual, capaz de generar oxígeno singlete desde su estado excitado singlete. En todos los casos se pudo demostrar la mayor contribución del mecanismo Tipo I sobre el mecanismo Tipo II en la fotodegradación de los diferentes contaminantes.
Finalmente, en la Parte II, el Capítulo 8 se dedicó a la reducción fotocatalítica de bromuros orgánicos, empleando Riboflavina, un colorante orgánico no metálico, como fotocatalizador. De nuevo, se prestó especial atención a la detección y comportamiento de las especies intermedias, lo que resultó de acuerdo a los datos termodinámicos.En les últimes dècades, els processos redox fotoinduïts mitjan per llum visible han rebut gran atenció degut a les suaus condicions d'operació en que es donen. Com a resultat, s'han aconseguit col·locar com una alternativa mes dins dels Processos d'Oxidació Avançada. A més, han estat convertint-se en una metodologia excepcional en síntesi orgànica, que ha obert la porta a noves rutes químiques amb aplicacions sintètiques. No obstant això, a pesar del creixement del camp, s'ha prestat poca atenció als mecanismes pels que operen aquests processos. El principal objectiu d'esta tesi va ser avançar en la comprensió de diferents processos fotoredox duts a terme emprant fotocatalitzadors orgànics. Més específicament, es va estudiar la viabilitat de distints fotocatalitzadors orgànics, i a més, es va realitzar un estudi mecanístic al detall basat en tècniques resoltes en el temps. Amb aquests resultats, es va establir una metodologia per a determinar els punts clau a considerar en un sistema fotoredox. En primer lloc, en la Part I, es van elegir dos fotocatalitzadors basats en sals de pirili i tiapirili, els quals operen per mitjà de transferència electrònica oxidativa, amb distints objectius. En el Capítol 3, es va avaluar la seua aplicabilitat en la fotodegradació de dos contaminants de la indústria del suro i es va estudiar el mecanisme pel qual es produeix dita fotodegradació. En el Capítol 4, es va demostrar la utilitat de la detecció directa de tots els intermedis de curt temps de vida derivats del TPP+ implicats en l'oxidació fotocatalitzada com a ferramenta per avaluar el nivell de fotodegradació. En el Capítol 5, es va emprar TPTP+ per a establir les millors característiques d'un fotocatalitzador i l'influencia de la concentració de les substàncies a oxidar en la eficiència dels estats oxidats, o en general, del intermedis claus de vida curta. En segon lloc, en la Part II, en el Capítol 6, es va avaluar el potencial del Rosa Bengala en l'eliminació de dos fàrmacs. Aquest es un fotocatalitzador típic en la remediació d'aigües residuals conegut per actuar via mecanisme Tipus II. Es va incloure a més un segon fotocatalitzador, Perinaftenona, el del qual rendiment quàntic d'oxigen singlet és inclús major a Rosa Bengala. En el Capítol 7, es va dur a terme la fotooxidació de tres contaminants, usant NMQ+, un fotocatalitzador inusual, capaç de generar oxigen singlet des del seu estat excitat singlet. En tots els casos es va poder demostrar la major contribució del mecanisme Tipus I sobre el mecanisme Tipo II en la fotodegradació dels diferents contaminants. Finalment, en la Part II, el Capítol 8 es va dedicar a la reducció fotocatalítica de bromurs orgànics, emprant Riboflavina, un colorant orgànic no metàl·lic, com fotocatalitzador. De nou, es va prestar especial atenció a la detecció i comportament de les espècies intermèdies, el que va resultar d'acord amb les dades termodinàmiques.
In the last decades, photoinduced-redox processes mediated through visible light have obtained great attention due to the generally mild operating conditions that they offer. As a result, they constitute a further alternative within the so-called Advanced Oxidation processes. Besides, they are becoming an outstanding methodology in organic synthesis, which has opened the door to new synthetic and chemical routes. However, despite the growth of the field, little attention has been paid to the mechanisms pathways behind these processes. The main objective of this thesis was to gain deeper understanding of different photoredox processes carried out using organic photocatalysts. More specifically, the viability of several organic photocatalysts was studied, and besides, a careful mechanistic study based on time resolved techniques supported the postulated mechanisms. With this information, a methodology determining the key points to consider in a photoredox system were stablished. Firstly, in Part I, two photocatalysts based on pyrilium and thiapyrilium salts, which operate through an oxidative electron transfer, have been used with different objectives. In Chapter 3, the viability of the photodegradation of two common pollutants from cork industry and the mechanism behind it has been evaluated. In Chapter 4, the direct detection of all the TPP+ derived short-lived intermediates in the photocatalyzed oxidation of a mixture of pollutants using TPP+ was proposed as a methodology to assess the photodegradation extent. In the last chapter of Part I, Chapter 5, TPTP+ is used to stablish the best characteristics of a photocatalyst. Besides, the study claimed the influence of the concentration of the target substances in the efficiency of the excited states or, in general, of the key short-lived intermediates. Secondly, in Part II, in Chapter 6, Rose Bengal, a typical photocatalyst used in wastewater remediation, known for working via Type II mechanism, was evaluated for the removal of two common drugs. In addition, a second one, Perinaphtenone, which exhibits even a higher singlet oxygen quantum yield than Rose Bengal was tested. In Chapter 7, NMQ+, a non-typical photocatalyst able of generate singlet oxygen from its singlet excited state, was used in the photooxidation of three different pollutants. In every case, the major contribution of Type I vs Type II mechanism was demonstrated. Finally, in Part III, Chapter 8 was devoted to the photocatalytic reduction of organic bromides. In this case, Riboflavine, a non-metallic organic dye, was used as a photocatalyst. Analogously, careful attention was paid to the behavoiur of the intermediates, which were in agreement, as well as to the thermodynamics of the steps involved in the photocatalytic cycle.
Martínez Haya, R. (2018). Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/114828
TESIS
46
Berry, Alexandra Fay Helen. "A chemical proteomic approach to investigate Rab prenylation in living systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/10926.
Full textAbstract:
Protein prenylation is an important post-translational modification that occurs in all eukaryotes; defects in the prenylation machinery can lead to toxicity or pathogenesis. Prenylation is the modification of a protein with a farnesyl or geranylgeranyl isoprenoid, and it facilitates protein-membrane and protein-protein interactions. Proteins of the Ras superfamily of small GTPases are almost all prenylated and of these the Rab family of proteins forms the largest group. Rab proteins are geranylgeranylated with up to two geranylgeranyl groups by the enzyme Rab geranylgeranyltransferase (RGGT). Prenylation of Rabs allows them to locate to the correct intracellular membranes and carry out their roles in vesicle trafficking. Traditional methods for probing prenylation involve the use of tritiated geranylgeranyl pyrophosphate which is hazardous, has lengthy detection times, and is insufficiently sensitive. The work described in this thesis developed systems for labelling Rabs and other geranylgeranylated proteins using a technique known as tagging-by-substrate, enabling rapid analysis of defective Rab prenylation in cells and tissues. An azide analogue of the geranylgeranyl pyrophosphate substrate of RGGT (AzGGpp) was applied for in vitro prenylation of Rabs by recombinant enzyme. Alternatively, geranylgeranylated proteins (including Rabs) were labelled with AzGG via metabolic labelling of live cells with AzGGOH. Once Rabs were tagged with an azide moiety they could be labelled via a bioorthogonal ligation reaction with a trifunctional alkyne probe. The probe contained a fluorophore for in-gel fluorescence analysis and a biotin affinity label for affinity purification of labelled proteins. The conditions for protein tagging, labelling, affinity purification and LC-MS/MS analysis were optimised significantly during this work. Affinity purified proteins were identified and in some cases quantified using LC-MS/MS techniques, with iTRAQ labelling for quantification. Rab prenylation was probed in cell culture, in cells treated with the drug Mevastatin and in tissue from mouse models with defects in the prenylation machinery.
47
Lucius, Ruth A. "Assessing corn quality and transformation during nixtamalization a physico-chemical approach /." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1231442056.
Full text
48
Zarzhitsky, Dimitri. "Physics-based approach to chemical source localization using mobile robotic swarms." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1663060071&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full text
49
FACCHINI, FABIO ALESSANDRO. "Toll-like Receptor 4 (TLR4) therapeutic modulation: a chemical biology approach." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198940.
Full textAbstract:
I recettori Toll-like (TLR) sono attivati in molte interazioni ospite-patogeno. Essi riconoscono pattern molecolari associati a patogeni (PAMP) inducendo la risposta immunitaria innata nell’ospite. Il TLR4 permette ai mammiferi di rilevare l’endotossina batterica, lipopolisaccaride (LPS). L’attivazione incontrollata del TLR4 è alla base di sepsi sistemica acuta e di molti disturbi infiammatori, come le malattie infiammatorie intestinali (IBD). La modulazione del TLR4 è pertanto di estremo interesse terapeutico. Questa tesi di dottorato si basa su tre articoli (capitolo 1-3) e ha lo scopo di studiare il potenziale ruolo terapeutico di piccole molecole attive sul TLR4, testate da sole o in combinazione con peptidi antimicrobici (AMP). Nel capitolo I mostriamo la progettazione e la caratterizzazione biologica di una serie di molecole anfifiliche con scaffold calixarenico. La struttura di questi composti è stata progettata mediante studi computazionali in modo da poter interagire con il complesso TLR4/MD-2 e con il co-recettore CD14. Alcuni calixareni ottenuti inibiscono l'attivazione di TLR4 indotta da LPS in modo dose-dipendente e riducono la produzione di citochine mediata da TLR4 in cellule immunitarie umane e murine. Inoltre, i guanidinocalixareni cationici sono in grado di inibire l’attivazione del TLR4 indotta dalla lectina PHA. Sebbene l’attività inibitoria dei guanidinocalixareni è stata correlata alla capacità di neutralizzare l’LPS, i risultati ottenuti in questo studio suggeriscono un effetto tali molecole diretto sul complesso TLR4/MD-2. La struttura dei calixareni potrebbe pertanto rivelarsi utile per lo sviluppo di nuovi modulatori del TLR4. Nel capitolo II sono riportati gli effetti della co-somministrazione di peptidi antimicrobici (AMP) con un antagonista sintetico del TLR4 (FP7) sull'attivazione del TLR4. Due AMP noti per neutralizzare LPS aumentano di un ordine di grandezza la potenza di FP7 nel bloccare il segnale mediato da TLR4. Questo effetto è mantenuto anche quando le cellule sono stimolate con un agonista del TLR4 diverso da LPS. I dati suggeriscono un possibile doppio meccanismo d’azione, non esclusivamente basato sulla capacità degli AMP di neutralizzare l’LPS, ma anche ad un effetto diretto sui recettori dell’endotossina. Esperimenti NMR in soluzione mostrano che l'aggiunta degli AMP modifica lo stato di aggregazione di FP7 promuovendo la formazione di micelle più grandi. Questi risultati suggeriscono una relazione tra lo stato di aggregazione di ligandi mimetici dell’LPS e il tipo/intensità della risposta mediata da TLR4. Il capitolo III descrive uno studio preclinico in cui l’antagonista FP7 è stato utilizzato in un modello sperimentale di malattia infiammatoria intestinale (IBD). Questo studio ha lo scopo di valutare una possibile strategia terapeutica basata sull'uso di piccole molecole dirette selettivamente sul complesso TLR4/MD-2 per ridurre l'infiammazione nelle IBD. I risultati ottenuti mostrano che FP7 riduce la secrezione di citochine proinfiammatorie indotta da LPS da parte di cellule mononucleate del sangue periferico (PBMC) e di cellule mononucleate della lamina propria (LPMC) isolate dai pazienti con IBD. L'effetto anti-infiammatorio di FP7 è dovuto ad una ridotta attivazione della via di segnalazione indotta da LPS dipendente dal fattore myeloid differentiation primary response gene (88) (Myd88). Lo studio mostra che il meccanismo di azione di FP7 è correlato alla sua capacità di competere con l’LPS per il legame con i recettori MD-2 e CD14. Inoltre FP7 riduce l'infiammazione in vivo su un modello murino di colite ulcerosa. Considerando che la patogenesi delle IBD è associata a un’eccessiva risposta immunitaria innata verso antigeni microbici, l'inibizione del TLR4 da parte di agenti chimici come FP7 potrebbe rivelarsi un promettente approccio alternativo al trattamento delle IBD.Among the first receptors activated during host-pathogen interactions are Toll-like receptors (TLRs), which detect pathogen-associated molecular patterns (PAMPs) to induce innate and adaptive immune responses. TLR4 is the mammalian sensor of bacterial endotoxin, lipopolysaccharide (LPS). Dysregulated TLR4 activation is involved in acute systemic sepsis and in many disorders that involve inflammation, including inflammatory bowel diseases (IBDs). Therefore, therapeutic modulation of TLR4 signalling is of major interest. This PhD thesis is based on three papers (Chapter 1-3) and has the aim to study the capacity of synthetic small molecule TLR4 antagonists, alone or in combination with antimicrobial peptides (AMPs), to act as therapeutics in inflammatory diseases. In Chapter I, starting from the assumption that opportunely designed cationic amphiphiles can behave as ligands of the LPS receptor system and therefore modulate the TLR4 signaling, we present the rational design and biological characterization of a panel of amphiphilic guanidinocalixarenes. The structure of these compounds was computationally designed and optimized to dock into MD-2 and CD14 binding sites. We found that some of these calixarenes were active in inhibiting, in a dose-dependent way, the LPS-stimulated TLR4 activation and TLR4-dependent cytokine production in human and mouse immune cells. Moreover, cationic guanidinocalixarenes also inhibited TLR4 signaling when TLR4 was activated by the plant lectin PHA. While the activity of guanidinocalixarenes in inhibiting LPS toxic action has previously been related to their capacity to bind and neutralize LPS, the results obtained in this chapter suggest a direct antagonist effect of calixarenes on TLR4/MD-2 dimerization: this suggests the use of the calixarene scaffold for the development of new TLR4-directed therapeutics. In Chapter II is presented the effect of co-administration of antimicrobial peptides (AMPs) and a synthetic TLR4 antagonist (the glycolipid FP7) on TLR4 activation and signalling. The co-administration of two LPS-neutralizing peptides (a cecropin A-melittin hybrid peptide and a human cathelicidin) enhances by an order of magnitude the potency of FP7 in blocking the TLR4 signal. Interestingly, this potentiation effect also occurs when cells are stimulated with a non-LPS TLR4 agonist. Our data suggest a dual mechanism of action for the peptide/glycolipid combination, not exclusively based on LPS binding and neutralization, but also on a direct effect on CD14 and MD-2 binding. NMR experiments in solution show that peptide addition changes the aggregation state of FP7, promoting the formation of larger micelles. These results suggest a relationship between the aggregation state of lipid A-like ligands and the type and intensity of TLR4 response. Chapter III describes a preclinical study in which FP7 is used in an experimental model of IBD. This study has the aim to evaluate a possible therapeutic strategy based on the use of small molecule that selectively targets TLR4/MD-2 complex to reduce IBD inflammation. The results obtained show that FP7 reduced the secretion of the main LPS-induced innate pro-inflammatory cytokines by peripheral blood mononuclear cells (PBMCs) and lamina propria mononuclear cells (LPMCs) isolated from IBD patients. FP7 anti-inflammatory effect is due to a reduced activation of the main myeloid differentiation primary response gene (88) (Myd88)-depedent pathway effectors normally induced by LPS presence. We indicated that the mechanism of action of FP7 is related to its capacity to compete with LPS for the binding to MD-2 adaptor protein and to CD14 co-receptor. FP7 also reduced inflammation in vivo on a murine model of ulcerative colitis. Considering that IBD pathogenesis is associated to an abnormal innate immune response towards microbial antigens, TLR4 inhibition by chemical agents as FP7 emerged as a promising alternative approach to IBD treatment.
50
Zhu, Yizu. "A molecular thermodynamic approach to phase partitioning of biomolecues and protein folding." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13141.
Full text