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Development of Cellulose-Titanium dioxide-Porphyrin Nanocomposite Films with High-barrier, UV-blocking, and Visible Light-Responsive Antimicrobial FeaturesLovely, Belladini 03 June 2024 (has links)
The packaging does not serve as a mere containment but also can be designed to play a key role in preserving the product from quality-deteriorating factors, including oxygen, light irradiation, and foodborne pathogenic microorganisms (e.g., Escherichia coli).
There has been a growing interest in employing ultra-porous metal-organic frameworks (MOF) with visible light-responsive antibacterial mechanisms to generate reactive oxygen species (ROS) that can eliminate bacteria via an oxidative burst. MOF is made of inorganic metal ions/nodes/clusters/secondary building units linked by organic bridge ligands, where titanium dioxide (TiO2) and tetrakis(4-carboxyphenyl)porphyrin) (TCPP) were selected for these components, respectively. TiO2 is an exceptional UV-A/B/C-blocker; meanwhile, TCPP dye performs a remarkable photocatalytic ability even under visible light, on top of its macro-heterocyclic structure that is ideal as a MOF linker. Both have good compatibility but suffer from the notorious tendency to self-quench/aggregate. The incorporation of MOF-based conjugates into a polymeric matrix, like cellulose, is among the proven-successful solutions. Cellulose is the Earth's most abundant and naturally biodegradable, and cellulose nanofibril (CNF) was particularly chosen for its high specific surface area and surface activity. However, a straightforward, cheap, and environmentally friendly approach of multicycle homogenization (0-25 passes) was conducted to solve neat cellulose's challenge of natural hydrophilicity, where low pressure (<10 MPa) was applied to prevent the common over-shearing effect. The antibacterial efficacy of CNF films functionalized with TiO2-TCPP conjugate on inhibiting E. coli growth was analyzed with and without light of different intensities (3000 and 6000 lux). The positive impacts of CNFs' promoted fibrillation and subsequent inter/intra-molecular hydrogen bonding post-homogenization were evidenced in an array of functional properties, i.e., crystallinity, TiO2-TCPP conjugate dispersion, surface smoothness, mechanical properties, thermal stability, hydrophobicity, oxygen barrier (comparable to ethylene-vinyl alcohol (EVOH), a commercial high-barrier polymer), and 100%-antibacterial rate (under 6000 lux after 72 hours). Varying optimum cycles of homogenization demonstrated the prospect of the proposed homogenization approach in preparing CNF with diverse processability and applicability. These findings also exhibited a promising potential for a myriad of high-barrier, UV-blocking, and/or visible light-responsive antibacterial film applications, including food packaging and biomedical. / Doctor of Philosophy / Packaging is useful not only as a container but can also be designed to help prevent products from being spoiled due to various reasons such as oxidation, light, and bacterial contamination. Researchers have discovered the promising antibacterial feature of the metal-organic framework (MOF). Packaging made with MOF technology can harness light and oxygen in the environment to produce a special form of oxygen called reactive oxygen species (ROS) that can kill unwanted bacteria. MOF is an extremely porous sponge-like material made of two ingredients: an inorganic metal cluster and an organic linker; in this study, titanium dioxide (TiO2) and a porphyrin called TCPP were selected, respectively. TiO2 is an excellent ultraviolet blocker, while TCPP has a unique, ring-like geometry that is ideal for use as a linker and an antimicrobial feature that works well under the visible light spectrum. The pair are compatible but still suffer from MOF's notorious challenge, where it tends to clump together because of its tiny size. To resolve this problem, TiO2-TCPP MOF can be deposited evenly in a cast made of polymer.
Cellulose has been proven to work effectively as a polymeric cast; moreover, it is natural, biodegradable, and in abundant supply. A type of nanosized cellulose—cellulose nanofibril (CNF)—was specifically chosen because its high surface area and activity are useful when blended with other materials. However, cellulose is naturally a poor water-repellant that is not ideal for packaging applications. As a solution, cellulose can be treated with a homogenization technique by passing the material through a very narrow hole under high pressure. Homogenization can be problematic as it possibly damages the cellulose's structure, and its high pressure can also be expensive and energy consuming.
Therefore, low pressure with multiple cycles was applied in this work. CNF-TiO2-TCPP films were tested for their ability to slow down E. coli bacteria growth with and without light of varying brightness to compare its light-sensitive antimicrobial feature.
Homogenization was found helpful in producing higher-quality CNF, which improved several of the film's final characteristics, including an even material dispersion, structural order, smoothness, strength, heat resistance, and water repellency. Most importantly, it produced films with oxygen barrier ability comparable to commercial high-barrier plastics and completely eliminated bacteria after 72 hours. The optimum number of homogenization cycles was found to be dependent on the desired characteristics and application. Overall, these findings carry a promising potential for a variety of applications, including food packaging and the biomedical field.
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New nitric oxide releasing materialsMcKinlay, Alistair C. January 2010 (has links)
The aim of this thesis was to examine the ability of metal organic frameworks (MOFs) to store and controllably release biologically significant amounts of nitric oxide (NO). Initial work involved the synthesis of a series of isostructural MOFs, known as M-CPO-27, which display coordinatively unsaturated metal sites (CUSs) when fully activated (guest solvent molecules both coordinated and uncoordinated to the metal atom are removed). Two of these frameworks (Ni and Co CPO-27) displayed exceptional performance over the entire cycle of activation, storage and delivery showing the largest storage and release of NO of any known porous material (up to 7 mmolg⁻¹). These frameworks would therefore be considered for initial research into the formulation of MOFs, for possible use in medical applications. It was shown that they still release large amounts of NO even when placed inside porous paper bags, creams or hydrocolloids. The other versions of M-CPO-27 also displayed significant adsorption of NO however they show poor total NO release. It was also shown that it is possible to synthesise both Ni and Co CPO-27 using microwave synthesis without any detrimental effect to the porous structure. Several iron-based MOFs were also investigated for NO storage and release. The results showed that Fe MIL-88 based structures adsorb good amounts of NO but only release a small amount of the irreversibly adsorbed NO. Two successfully amine grafted giant pore MOFs were then investigated to attempt to improve the NO adsorption and release. This result was not observed however, due to the poor total amine grafting coverage and pore blockage resulting from the amines. In-situ IR studies reveal that when exposed to NO, activated Fe MIL-100 forms a chemical bond with the NO. The studies also displayed that when water is then allowed to attempt to replace the NO that only a small amount of NO is actually released, the majority of the NO either remains chemically bonded to the Fe atom or forms N₂O in conjunction with a Fe-OH group. Other MOFs were also successfully synthesised and characterised for NO storage and release. Both Ni succinate and Ni STA-12 display good adsorption and excellent release of NO. This indicates that Ni based MOFs show the best results for NO adsorption and release. In the conclusion of the thesis I am able to categorise the NO release ability of MOFs based on composition and formulate a theory as to why this happens.
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High-throughput screening: speeding up porous materials discoveryWollmann, Philipp, Leistner, Matthias, Stoeck, Ulrich, Grünker, Ronny, Gedrich, Kristina, Klein, Nicole, Throl, Oliver, Grählert, Wulf, Senkovska, Irena, Dreisbach, Frieder, Kaskel, Stefan 31 March 2014 (has links) (PDF)
A new tool (Infrasorb-12) for the screening of porosity is described, identifying high surface area materials in a very short time with high accuracy. Further, an example for the application of the tool in the discovery of new cobalt-based metal–organic frameworks is given. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Application of a chiral metal–organic framework in enantioselective separationPadmanaban, Mohan, Müller, Philipp, Lieder, Christian, Gedrich, Kristina, Grünker, Ronny, Bon, Volodymyr, Senkovska, Irena, Baumgärtner, Sandra, Opelt, Sabine, Paasch, Silvia, Brunner, Eike, Glorius, Frank, Klemm, Elias, Kaskel, Stefan 31 March 2014 (has links) (PDF)
A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal–organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reported. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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A highly porous metal–organic framework, constructed from a cuboctahedral super-molecular building block, with exceptionally high methane uptakeStoeck, Ulrich, Krause, Simon, Bon, Volodymyr, Senkovska, Irena, Kaskel, Stefan 03 April 2014 (has links) (PDF)
A highly porous metal–organic framework Cu2(BBCDC) (BBCDC = 9,9′-([1,1′-[b with combining low line]iphenyl]-4,4′-diyl)[b with combining low line]is(9H-[c with combining low line]arbazole-3,6-[d with combining low line]i[c with combining low line]arboxylate) (DUT-49) with a specific surface area of 5476 m2 g−1, a pore volume of 2.91 cm3 g−1, a H2 excess uptake of 80 mg g−1 (77 K, 50 bar), a CO2 excess uptake of 2.01 g g−1 (298 K, 50 bar) and an exceptionally high excess methane storage capacity of 308 mg g−1 (298 K, 110 bar) was obtained using an extended tetratopic linker. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Control of water and toxic gas adsorption in metal-organic frameworksMcPherson, Matthew Joseph January 2016 (has links)
The research presented in this thesis aims to determine the effectiveness of the uptake of toxic gases by several MOFs for future use in gas-mask cartridges, and to attempt to compensate for any deficiencies they show in “real-world” conditions. The main findings of this thesis confirm that MOFs are suitable candidates for the use in respirator cartridge materials and provide high capacity for adsorption of toxic gases like ammonia and STAM-1 in particular showed an impressive improvement in humid conditions, which normally decrease the performance of MOFs made from the same materials, such as HKUST-1. STAM-1's improved performance in humid conditions is attributed to the structural shift it displays upon dehydration and rehydration and this was shown to be the case in a structural analogue, CuEtOip, which was synthesised in the author's research group. This analogue was analysed using a combination of single crystal XRD and solid state MAS-NMR, both of which showed the structural change occurring and displays similar gas sorption behaviours, suggesting that this mechanism is the source of STAM-1's improved performance in humid conditions. This thesis also examines the “Armoured MOF” process and investigates the transferability of the process of deposition of mesoporous silica onto MOFs with vastly different properties and synthetic methods compared to those published in the original publication. Alongside this, attempts to protect MOFs using mesoporous silicates were investigated for their viability.
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Comment la répartition des rôles et tâches influence l'efficacité du support et des opérations informatiquesBouvrette, Nicolas 05 1900 (has links) (PDF)
Cette recherche porte sur les facteurs d'influence de l'efficacité des opérations et du support TI. Plus précisément nous cherchons à connaître l'impact de la répartition des rôles et des tâches sur l'efficacité. En identifiant ces facteurs, il serait possible d'aider de futures recherches ou projets afin de modéliser une situation organisationnelle optimale. Plusieurs référentiels connus ont tenté de généraliser les meilleures pratiques dans ce domaine, mais ce sujet reste largement sous-exploité par le milieu académique. Nous avons donc tenté de percer le mystère des facteurs d'influence et de comprendre si la répartition de rôles et des tâches a un impact important sur l'efficacité. En second lieu, plusieurs autres variables ont été ajoutées à l'analyse telles que la maturité, la performance, les outils, les compétences et la situation professionnelle. C'est à l'aide des référentiels existants (ITIL, COBIT, MOF, etc.) que la revue de littérature a permis d'établir les variables entourant la question principale de cette recherche. Les facteurs d'influence retenus pour cette recherche ont alors été utilisés afin de construire un questionnaire permettant de faire la lumière sur les interrelations existantes dans le secteur professionnel montréalais. Une fois les données collectées, plusieurs méthodes d'analyse statistique ont été utilisées afin de trouver toutes relations existantes parmi ces variables. Les résultats sont quand même intéressants, même s'ils démontrent que la répartition des rôles et des tâches semble avoir une faible influence sur l'efficacité. On explique en partie cette situation à l'aide des variables concernant l'expertise requise afin d'exécuter les tâches spécifiques aux opérations et support TI. Le résultat final semble sensiblement le même, peu importe qui est responsable de ces tâches. Ce même constat s'applique autant aux tâches bien maîtrisées que celles moins connues par les professionnels du secteur. Par contre, d'autres liens seront découverts et discutés, tels que l'influence de l'utilisation d'outils sur la performance ainsi que celle de la maturité sur l'efficacité.
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MOTS-CLÉS DE L’AUTEUR : rôles, tâches, opérations, support, TI, efficacité, performance, maturité, outils, ITIL, COBIT, MOF.
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Function of granulocytes after burns and trauma, associations with pulmonary vascular permeability, acute respiratory distress syndrome, and immunomodulationJohansson, Joakim January 2013 (has links)
Background: Our innate immunesystem protects us from infections but, since its methods is not all specific for microorganisms, may also induce collateral damage. Severe physical injury often proved deadly throughout evolution. Such injuries may induce massive collateral damage. Nowadays we can initiate advanced critical care for affected patients and save them from imminent trauma-related death. We are therefore faced with the fact that the collateral damage from the immune system may pose a major threat to the patient, the pathophysiology of which is not amenable to direct medical treatment and which leaves us with only passive supportive measures. In this thesis we investigated the role of leucocytes under such circumstances. Our main aim was to understand better the role of leucocytes in the development of increased vascular permeability after burns and trauma. More specifically we investigated the impact of an injury on the function of leucocytes such as the dynamic change of certain cell-surface receptors on the leucocytes and in their numbers and immature forms. We wanted to find out if the increased pulmonary vascular permeability after a burn could be mediated through heparin binding protein (HBP) released from granuloctes, and whether HBP could be used as a biomarker for respiratory failure after trauma. We also wanted to confirm the possible role of histamine as a mediator of the systemic increase in vascular permeability after burns. Methods: The dynamic change of cell-surface receptors was measured by flow-acquired cytometer scanning (FACS) on blood samples taken after burns. The concentrations of HBP after a burn and mechanical trauma were analysed in plasma. Pulmonary vascular permeability after a burn was assessed using transpulmonary thermodilution. The histamine turnover after a burn was assessed with high performance liquid chromatography (HPLC) for concentrations of histamine and methylhistamine in urine. Results: We confirmed earlier investigations showing altered expression of receptors on leucocytes after a burn, receptors intimately associated with leucocyte functions (study I). In a pilot study of 10 patients we measured plasma concentrations of HBP and found them to be increased soon after a burn (study II). This finding was not confirmed in a larger, more extensive and specific study of 20 patients. We did, however, find an association between alterations in the number of leucocytes soon after a burn and pulmonary vascular permeability, indicating that they had a role in this process (study III). In another study of trauma (non burn) we found an association between the concentration of HBP in early plasma-samples after injury and the development of ARDS, indicating that granulocytes and HBP have a role in its aetiology (study IV). We found a small increase in urinary histamine and normal urinary methylhistamine concentrations but had anticipated a distinct increase followed by a decrease after reading the current papers on the subject. This indicates that the role of histamine as a mediator of increased vascular permeability after burns may have been exaggerated (study V). Conclusions: We conclude that leucocytes are affected by burns and trauma, and it is likely that they contribute to the development of respiratory failure and acute respiratory distress syndrome (ARDS). HBP is a candidate biomarker for the early detection of ARDS after trauma, and the white blood count (WBC) is a useful biomarker for the detection of decreased oxygenation soon after a burn.
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A new metal–organic framework with ultra-high surface areaGrünker, Ronny, Bon, Volodymyr, Müller, Philipp, Stoeck, Ulrich, Krause, Simon, Mueller, Uwe, Senkovska, Irena, Kaskel, Stefan 21 July 2014 (has links) (PDF)
A new mesoporous MOF, Zn4O(bpdc)(btctb)4/3 (DUT-32), containing linear ditopic (bpdc2−; 4,4′-biphenylenedicarboxylic acid) and tritopic (btctb3−; 4,4′,4′′-[benzene-1,3,5-triyltris(carbonylimino)]tris-benzoate) linkers, was synthesised. The highly porous solid has a total pore volume of 3.16 cm3 g−1 and a specific BET surface area of 6411 m2 g−1, adding this compound to the top ten porous materials with the highest BET surface area.
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A family of 2D and 3D coordination polymers involving a trigonal tritopic linkerHauptvogel, Ines Maria, Bon, Volodymyr, Grünker, Ronny, Baburin, Igor A., Senkovska, Irena, Müller, Uwe, Kaskel, Stefan 08 April 2014 (has links) (PDF)
Five new coordination polymers, namely, [Zn2(H2O)2(BBC)](NO3)(DEF)6 (DUT-40), [Zn3(H2O)3(BBC)2] (DUT-41), [(C2H5)2NH2][Zn2(BBC)(TDC)](DEF)6(H2O)7 (DUT-42), [Zn10(BBC)5(BPDC)2(H2O)10](NO3)(DEF)28(H2O)8 (DUT-43), and [Co2(BBC)(NO3)(DEF)2(H2O)](DEF)6(H2O) (DUT-44), where BBC – 4,4′,4′′-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate, TDC – 2,5-thiophenedicarboxylate, BPDC – 4,4′-biphenyldicarboxylate, DEF – N,N-diethylformamide, were obtained under solvothermal conditions and structurally characterized. It has been shown that compounds DUT-40, DUT-41 and DUT-44 exhibit 2D layered structures with large hexagonal channels. Utilization of additional angular dicarboxylic TDC linker led to the formation of the DUT-42 compound with the structure consisting of three interpenetrated 3D networks. Using the linear co-linker dicarboxylic BPDC, DUT-43 was obtained which forms a complicated 3D architecture arising from the polycatenation of triple-layered 2D building units and 2D single layer units. The pore accessibility of the synthesized compounds in the liquid phase was proved by the adsorption of dye molecules. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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