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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.
1

Energetic Molecules as Future Octane Boosters: Theoretical and Experimental Study

Al-Khodaier, Mohannad 06 1900 (has links)
The utilization of energetic strained molecules may be one way to mitigate carbon emissions or better and more economical fuel blends. To investigate candidate molecules, limonene and dicyclopentadiene, both theoretical and experimental procedures were implemented here. Computational quantum chemistry methods were employed to determine the thermodynamic properties and kinetic parameters for the hydrogen-abstraction reactions of limonene by a hydrogen atom. Geometry optimization and energy calculation was conducted for all stable species and transition states using Gaussian 09. The rate constants of the H-abstraction reactions were calculated using conventional transition state theory, as implemented in ChemRate software. The obtained values were fitted over the temperature range of 298 – 2000 K to obtain the modified Arrhenius parameters. Increasing the anti-knock quality of gasoline fuels can enable higher efficiency in spark ignition engines. This study explores blending the anti-knock quality of dicyclopentadiene (DCPD, a by-product of ethylene production from naphtha cracking), with various gasoline fuels. The blends were tested in an ignition quality tester (IQT) and a modified cooperative fuel research (CFR) engine operating under homogenous charge compression ignition (HCCI) and knock limited spark advance (KLSA) conditions. Ethanol is widely used as a gasoline blending component in many markets, due to current fuel regulations. The test results of DCPD-gasoline blends were compared to those of ethanol-gasoline blends. Furthermore, the anti-knock properties of dicyclopentadiene (DCPD) as an additive to primary reference fuels (PRF) and toluene primary reference fuels (TPRF) have been investigated. The research octane number (RON) and motor octane number (MON) were measured using cooperative fuels research (CFR) engine for four different fuel blends. Moreover, the ignition delay times of these mixtures were measured in a high-pressure shock tube at 40 bar and stoichiometric mixtures over a temperature range of [700-1200 K]. Ignition delay measurements were also conducted using rapid compression machine (RCM) at stoichiometric conditions and 20 bar. An ignition quality tester (IQT) compared ignition delay times of iso-octane and DCPD. Furthermore, a chemical kinetic auto-ignition model was designed to simulate the IDT experiments.
2

Synthetic biology for synthetic chemistry - Microbial production and selective functionalization of limonene

Willrodt, Christian 06 April 2016 (has links) (PDF)
The progress in biotechnological disciplines such as metabolic engineering or synthetic biology increased the interest of chemical and pharmaceutical industries to implement microbial processes for chemical synthesis. However, most microorganisms, e.g., Escherichia coli or Saccharomyces cerevisiae, used in biotechnological applications are not evolved by nature for the production of industrially relevant compounds, which are often hydrophobic, non-charged, volatile, or toxic to the microbial organisms. Bioprocess design relies on an integrated approach addressing pathway, cellular, reaction, and process engineering to combine the results of natural evolution with the demands of industrial applicability. In this thesis, the microbial de novo production and selective oxyfunctionalization of the highly volatile isoprenoid limonene has been investigated as a model system featuring reactants with challenging physicochemical characteristics. Key constraints that limit limonene biosynthesis and its oxyfunctionalization in recombinant E. coli, related to genetics, physiology, and reaction engineering, were identified and relieved.
3

Development and Validation of a Novel Assay to Quantify D-Limonene in Human Adipose Biopsies

Miller, Jessica Anne January 2007 (has links)
d-Limonene is a lipid-soluble bioactive food component found in citrus peel. It has demonstrated strong chemopreventive effects in rodent mammary, gastric, skin, liver, and lung cancers and is correlated with a significantly reduced risk for human squamous cell skin carcinoma. Because d-limonene is fat-soluble, it may have enhanced chemopreventive activity in fatty tissues such as breast. No previous methodology to quantify d-limonene in the adipose had been developed which significantly limited d-limonene tissue distribution research. For this research, an assay to extract d-limonene from adipose tissue and quantify with GC/MS was developed and validated. Linear calibration curves were established over the range of 0.0-2,526 ng d-limonene. Extraction recovery was 80%. Satisfactory within day precision (RSD 6.75 to 9.56%) and accuracy (% difference of 2-4%) were achieved. This sensitive, accurate, and precise assay to quantify d-limonene in adipose can be used for future human or animal fatty tissue deposition studies.
4

Copolymerization of Limonene

Zhang, Yujie January 2014 (has links)
In this thesis, we explored the use of a renewable resource to produce more sustainable polymeric materials. Limonene, a monocyclic terpene existing in many essential oils extracted from citrus rinds, was the renewable monomer investigated. The d-limonene ((+)-limonene) isomer is a major component (~90%) of orange oils from orange juicing and peel processing. Having been used as a flavour and fragrance additive in cosmetics, foods and beverages, as well as a green solvent, limonene is of particular interest in polymerization, because it contains double bonds, which provide the bifunctionality necessary for polymerization. Limonene is also an allylic monomer (CH2=CH-CH2Y), which presents challenges in free-radical homopolymerization and thus, copolymerization was investigated herein to overcome this difficulty. 2-Ethylhexyl acrylate (EHA) and n-butyl methacrylate (BMA) were used in two separate projects, as comonomers with limonene. Using bulk free-radical copolymerization at 80℃, with benzoyl peroxide (BPO) as the initiator, high molecular weight (>100,000) EHA/limonene and BMA/limonene copolymers were produced. Reactivity ratios, important parameters used in the prediction of copolymer composition, were estimated and shown to accurately predict the copolymer composition of subsequent experiments. These can now be used for the application of appropriate semi-batch policies to further enhance limonene incorporation into the copolymers.
5

Bioavailability and Disposition of the Bioactive Food Component D-Limonene, and Implications for Breast Cancer Prevention

Miller, Jessica A. January 2010 (has links)
d-Limonene is a monoterpene found in high concentration in citrus peel oil. Evidence from animal models and cell culture indicate that it has strong anti-cancer effects, particularly in mammary cancer models. Chapter 1; "D-LIMONENE: A BIOACTIVE FOOD COMPONENT FROM CITRUS AND EVIDENCE FOR A POTENTIAL ROLE IN BREAST CANCER PREVENTION AND TREATMENT" is a review paper accepted to Oncology Reviews. This review describes the evidence for <italic>d<italic>-limonene's anti-cancer mechanisms, bioavailability and safety, focusing on relevance to breast cancer prevention. Chapter 2; "ADIPOSE TISSUE ACCUMULATION OF D-LIMONENE WITH THE CONSUMPTION OF A LEMONADE PREPARATION RICH IN D-LIMONENE CONTENT" is published in Nutrition and Cancer journal and describes a phase I clinical trial in which participants consumed 40 oz of high-limonene lemonade daily. This study demonstrated that after 4 weeks of oral consumption of high-limonene lemonade, d-limonene deposits in high levels in adipose tissue. Chapter 3; "A CLINICAL BIOMARKER STUDY OF TOPICALLY APPLIED D-LIMONENE FOR BREAST CANCER PREVENTION" was submitted to Nutrition and Cancer journal. In this phase 0 clinical study, four weeks of a 10% d-limonene formulation resulted in minimal change in NAF and plasma biomarkers or d-limonene levels. Biomarkers in NAF and plasma, however, were significantly differently correlated with BMI and menopausal status, perhaps suggesting effect modifications. Chapter 4: "MOUSE MAMMARY TISSUE DISTRIBUTION OF D-LIMONENE AND PERILLIC ACID FOLLOWING ORAL AND TOPICAL D-LIMONENE ADMINISTRATION," was a study comparing d-limonene and perillic acid disposition after administration of 10% and 20% d-limonene in coconut oil in topical and oral forms to SKH-1 mice. This study demonstrated that d-limonene deposits in high levels in mouse mammary tissue after both oral and topical administration short-term, but is largely cleared after 24 hours in this model. Perillic acid deposits in high levels in adipose after oral administration, and these high concentrations remained after 24 hours. Chapter 5: "IMPLICATIONS AND FUTURE DIRECTIONS" provides a summary of the key findings from these three projects and proposals for future research. The appendices provide results from smaller d-limonene projects, as well as extensions of the body of the dissertation work.
6

CHIRAL POLYMER PHOTODETECTOR

Zhang, YIWEI 25 March 2014 (has links)
A polymer photodetector is fabricated using polythiophene with chiral alkyl side chains. The Cotton effect is observed in the CD spectrum of the photodetector, indicating an unequal absorbance of left- and right-handed circular polarized light (CPL). The photodetector is proven to be able to identify incident left- and right-handed CPL. Polymer photodetectors that are made from R- and S-limonene induced achiral polymers are fabricated. A “hot spin-coating” process is introduced to cast uniform limonene induced polymer films. As a result of chirality transfer, Cotton effects are also observed in these photodetectors’ CD spectra. A model is suggested to explain the chirality generation of the polythiophene with chiral alkyl side chains and limonene induced achiral polymers. / Thesis (Master, Chemistry) -- Queen's University, 2014-03-25 14:37:23.168
7

Cold Pasteurization Of Tender Coconut Water By A Batch And Flow Processes Using Glassbeads Coated With Phytochemicals Encapsulated Nano-Liposomes

Thomson, Jim 01 May 2018 (has links)
Tender coconut water (TCW) is one of most consumed natural energy drinks. Although it is widely available in tropical countries, because of its natural health benefits it is increasingly consumed in other parts of the world. Therefore there has been an increased requirement for packaging and shipping. TCW is highly susceptible to microbial contamination during extraction and packaging, requiring pasteurization. Thermal pasteurization leads to loss of flavor and color of coconut water. The purpose of this study was to test the feasibility of a non-thermal method of pasteurization of TCW using natural antimicrobials like curcumin, eugenol, and d-limonene with curcumin. The non-thermal pasteurization method was developed in two different processes, i.e. a batch and flow-filter process. Batch cold pasteurization process was conducted by suspending liposome encapsulated antimicrobials immobilized on glassbeads in TCW at 4oC by shake flask assay. Maximum Reduction of Listeria monocytogenes and Escherichia coli W1485 in pasteurized TCW were observed to be 5 log CFU per ml of TCW within 7 days of incubation under the presence of nano-liposomes containing 50 mM of curcumin, d- limonene or eugenol. There was no change in color and aroma of TCW after 1 month of storage at 4oC. the flow filter cold pasteurization process was developed using filter medium coated with nano-liposomes encapsulated antimicrobial leading to extended release of the natural antimicrobial curcumin to the coconut water in 4oC. Listeria monocytogenes and E. coli W1485 were used as model organisms to test effectiveness of cold pasteurization. Reduction of L. monocytogenes and E. coli W1485 in pasteurized TCW was observed to be 5.2 and 4.5 log10CFU/ml of TCW respectively within 17.25 min of incubation under the presence of nano-liposomes containing 50 mM of curcumin. There was no change in color and aroma of TCW after 1 week of storage at 4oC.
8

Síntese e avaliação da atividade farmacológica in vitro de aminas derivadas do limoneno

Graebin, Cedric Stephan January 2008 (has links)
O limoneno é um produto natural da classe dos terpenos, encontrado abundantemente em plantas cítricas e relatado na literatura como um composto com atividades farmacológicas interessantes, entre elas antibacteriana, antifúngica, antileishmania, nociceptiva e citotóxica. A presente tese relata a funcionalização do limoneno utilizando a Síntese Orgânica em Fase Sólida e a Síntese Orgânica Clássica (em solução). A partir da síntese orgânica em solução, especialmente através das reações de hidroformilação e hidroaminometilação, obtiveram-se vinte compostos. Os compostos foram testados para várias atividades farmacológicas in vitro, a saber: antibacteriana, antifúngica, anti-tripanossoma e anti-leishmania. Destes, dezessete foram testados para a atividade anti-leishmania in vitro contra formas promastigotas de L. (V.) braziliensis e sete apresentaram atividade superior ao fármaco pentamidina, utilizado como padrão no teste, com valores de IC50 entre 11,5 e 35,6 μM. / Limonene is a natural product from the terpene family, found in great proportions in citrical plants, being reported in the literature as having interesting pharmacological activities, such as antibacterial, antifungical, antileishmanial, nociceptive and citotoxic. This thesis reports the funcionalization of limonene via Solid-Phase Organic Synthesis and classical solution-phase synthesis. Twenty products were obtained from the solution-phase protocols, especially from reactions such as hydroformylation and hydroaminomethylation. The compounds were tested for several pharmacological activities, e.g.: antibacterial, antifungical, anti-tripanossomal and anti-leishmanial. Seventeen of those compounds were tested against in vitro promastigote strains of Leishmania (V.) braziliensis and seven compounds were found to have greater anti-leishmanial activity than pentamidine, the standard drug used in this test, presenting IC50 values ranging from 11,5 to 35,6 μM.
9

Síntese e avaliação da atividade farmacológica in vitro de aminas derivadas do limoneno

Graebin, Cedric Stephan January 2008 (has links)
O limoneno é um produto natural da classe dos terpenos, encontrado abundantemente em plantas cítricas e relatado na literatura como um composto com atividades farmacológicas interessantes, entre elas antibacteriana, antifúngica, antileishmania, nociceptiva e citotóxica. A presente tese relata a funcionalização do limoneno utilizando a Síntese Orgânica em Fase Sólida e a Síntese Orgânica Clássica (em solução). A partir da síntese orgânica em solução, especialmente através das reações de hidroformilação e hidroaminometilação, obtiveram-se vinte compostos. Os compostos foram testados para várias atividades farmacológicas in vitro, a saber: antibacteriana, antifúngica, anti-tripanossoma e anti-leishmania. Destes, dezessete foram testados para a atividade anti-leishmania in vitro contra formas promastigotas de L. (V.) braziliensis e sete apresentaram atividade superior ao fármaco pentamidina, utilizado como padrão no teste, com valores de IC50 entre 11,5 e 35,6 μM. / Limonene is a natural product from the terpene family, found in great proportions in citrical plants, being reported in the literature as having interesting pharmacological activities, such as antibacterial, antifungical, antileishmanial, nociceptive and citotoxic. This thesis reports the funcionalization of limonene via Solid-Phase Organic Synthesis and classical solution-phase synthesis. Twenty products were obtained from the solution-phase protocols, especially from reactions such as hydroformylation and hydroaminomethylation. The compounds were tested for several pharmacological activities, e.g.: antibacterial, antifungical, anti-tripanossomal and anti-leishmanial. Seventeen of those compounds were tested against in vitro promastigote strains of Leishmania (V.) braziliensis and seven compounds were found to have greater anti-leishmanial activity than pentamidine, the standard drug used in this test, presenting IC50 values ranging from 11,5 to 35,6 μM.
10

Síntese e avaliação da atividade farmacológica in vitro de aminas derivadas do limoneno

Graebin, Cedric Stephan January 2008 (has links)
O limoneno é um produto natural da classe dos terpenos, encontrado abundantemente em plantas cítricas e relatado na literatura como um composto com atividades farmacológicas interessantes, entre elas antibacteriana, antifúngica, antileishmania, nociceptiva e citotóxica. A presente tese relata a funcionalização do limoneno utilizando a Síntese Orgânica em Fase Sólida e a Síntese Orgânica Clássica (em solução). A partir da síntese orgânica em solução, especialmente através das reações de hidroformilação e hidroaminometilação, obtiveram-se vinte compostos. Os compostos foram testados para várias atividades farmacológicas in vitro, a saber: antibacteriana, antifúngica, anti-tripanossoma e anti-leishmania. Destes, dezessete foram testados para a atividade anti-leishmania in vitro contra formas promastigotas de L. (V.) braziliensis e sete apresentaram atividade superior ao fármaco pentamidina, utilizado como padrão no teste, com valores de IC50 entre 11,5 e 35,6 μM. / Limonene is a natural product from the terpene family, found in great proportions in citrical plants, being reported in the literature as having interesting pharmacological activities, such as antibacterial, antifungical, antileishmanial, nociceptive and citotoxic. This thesis reports the funcionalization of limonene via Solid-Phase Organic Synthesis and classical solution-phase synthesis. Twenty products were obtained from the solution-phase protocols, especially from reactions such as hydroformylation and hydroaminomethylation. The compounds were tested for several pharmacological activities, e.g.: antibacterial, antifungical, anti-tripanossomal and anti-leishmanial. Seventeen of those compounds were tested against in vitro promastigote strains of Leishmania (V.) braziliensis and seven compounds were found to have greater anti-leishmanial activity than pentamidine, the standard drug used in this test, presenting IC50 values ranging from 11,5 to 35,6 μM.

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