16 research outputs found

    Biomass Processing for Biofuels, Bioenergy and Chemicals

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    Biomass can be used to produce renewable electricity, thermal energy, transportation fuels (biofuels), and high-value functional chemicals. As an energy source, biomass can be used either directly via combustion to produce heat or indirectly after it is converted to one of many forms of bioenergy and biofuel via thermochemical or biochemical pathways. The conversion of biomass can be achieved using various advanced methods, which are broadly classified into thermochemical conversion, biochemical conversion, electrochemical conversion, and so on. Advanced development technologies and processes are able to convert biomass into alternative energy sources in solid (e.g., charcoal, biochar, and RDF), liquid (biodiesel, algae biofuel, bioethanol, and pyrolysis and liquefaction bio-oils), and gaseous (e.g., biogas, syngas, and biohydrogen) forms. Because of the merits of biomass energy for environmental sustainability, biofuel and bioenergy technologies play a crucial role in renewable energy development and the replacement of chemicals by highly functional biomass. This book provides a comprehensive overview and in-depth technical research addressing recent progress in biomass conversion processes. It also covers studies on advanced techniques and methods for bioenergy and biofuel production

    On-Chip Fabry-PĂ©rot Microcavity for Refractive Index Cytometry and Deformability Characterization of Single Cells

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    Une identification correcte et prĂ©cise du phĂ©notype et des fonctions cellulaires est fondamentale pour le diagnostic de plusieurs pathologies ainsi qu’à la comprĂ©hension de phĂ©nomĂšnes biologiques tels que la croissance, les rĂ©ponses immunitaires et l’évolution de maladies. ConsĂ©quemment, le dĂ©veloppement de technologies de pointe offrant une mesure multiparamĂ©trique Ă  haut dĂ©bit est capital. À cet Ă©gard, la cytomĂ©trie en flux est l’étalon de rĂ©fĂ©rence due Ă  sa grande spĂ©cificitĂ©, sa grande sensibilitĂ© et ses dĂ©bits Ă©levĂ©s. Ces performances sont atteintes grĂące Ă  l’évaluation prĂ©cise du taux d’émission de fluorophores, conjuguĂ©s Ă  des anticorps, ciblant certains traits cellulaires spĂ©cifiques. NĂ©anmoins, sans ce prĂ©cieux Ă©tiquetage, les propriĂ©tĂ©s physiques caractĂ©risĂ©es par la cytomĂ©trie sont limitĂ©es Ă  la taille et la granularitĂ© des cellules. Bien que la cytomĂ©trie en flux soit fondamentalement un dĂ©tecteur optique, elle ne tire pas avantage de l’indice de rĂ©fraction, un paramĂštre reflĂ©tant la composition interne de la cellule. Dans la littĂ©rature, l’indice de rĂ©fraction cellulaire a Ă©tĂ© utilisĂ© comme paramĂštre phĂ©notypique discriminant pour la dĂ©tection de nombreux cancers, d’infections, de la malaria ou encore de l’anĂ©mie. Également, les structures fluidiques de la cytomĂ©trie sont conçues afin d’empĂȘcher une dĂ©formation cellulaire de se produire. Cependant, les preuves que la dĂ©formabilitĂ© est un indicateur de plusieurs pathologies et d’état de santĂ© cellulaire sont manifestes. Pour ces raisons, l’étude de l’indice de rĂ©fraction et de la dĂ©formabilitĂ© cellulaire en tant que paramĂštres discriminants est une avenue prometteuse pour l’identification de phĂ©notypes cellulaires. En consĂ©quence, de nombreux biodĂ©tecteurs qui exploitent l’une ou l’autre de ces propriĂ©tĂ©s cellulaires ont Ă©mergĂ© au cours des derniĂšres annĂ©es. D’une part, les dispositifs microfluidiques sont des candidats idĂ©aux pour la caractĂ©risation mĂ©canique de cellules individuelles. En effet, la taille des structures microfluidiques permet un contrĂŽle rigoureux de l’écoulement ainsi que de ses attributs. D’autre part, les dispositifs microphotoniques excellent dans la dĂ©tection de faibles variations d’indice de rĂ©fraction, ce qui est critique pour un phĂ©notypage cellulaire correcte. Par consĂ©quent, l’intĂ©gration de composants microfluidiques et microphotoniques Ă  l’intĂ©rieur d’un dispositif unique permet d’exploiter ces propriĂ©tĂ©s cellulaires d’intĂ©rĂȘt. NĂ©anmoins, les dispositifs capables d’atteindre une faible limite de dĂ©tection de l’indice de rĂ©fraction tels que les dĂ©tecteurs Ă  champ Ă©vanescent souffrent de faibles profondeurs de pĂ©nĂ©tration. Ces dispositifs sont donc plus adĂ©quats pour la dĂ©tection de fluides ou de molĂ©cules. De maniĂšre opposĂ©e, les dĂ©tecteurs interfĂ©romĂ©triques tels que les Fabry- PĂ©rots sont sensibles aux Ă©lĂ©ments prĂ©sents Ă  l’intĂ©rieur de leurs cavitĂ©s, lesquelles peuvent mesurer jusqu’à plusieurs dizaines de micromĂštres.----------Abstract Accurate identification of cellular phenotype and function is fundamental to the diagnostic of many pathologies as well as to the comprehension of biological phenomena such as growth, immune responses and diseases development. Consequently, development of state-of-theart technologies offering high-throughput and multiparametric single cell measurement is crucial. Therein, flow cytometry has become the gold standard due to its high specificity and sensitivity while reaching a high-throughput. Its marked performance is a result of its ability to precisely evaluate expression levels of antibody-fluorophore complexes targeting specific cellular features. However, without this precious fluorescence labelling, characterized physical properties are limited to the size and granularity. Despite flow cytometry fundamentally being an optical sensor, it does not take full advantage of the refractive index (RI), a valuable labelfree measurand which reflects the internal composition of a cell. Notably, the cellular RI has proven to be a discriminant phenotypic parameter for various cancer, infections, malaria and anemia. Moreover, flow cytometry is designed to prevent cellular deformation but there is growing evidence that deformability is an indicator of many pathologies, cell health and state. Therefore, cellular RI and deformability are promising avenues to discriminate and identify cellular phenotypes. Novel biosensors exploiting these cellular properties have emerged in the last few years. On one hand, microfluidic devices are ideal candidates to characterize single cells mechanical properties at large rates due to their small structures and controllable flow characteristics. On the other hand, microphotonic devices can detect very small RI variations, critical for an accurate cellular phenotyping. Hence, the integration of microfluidic and microphotonic components on a single device can harness these promising cellular physical properties. However, devices achieving very small RI limit of detection (LOD) such as evanescent field sensors suffer from very short penetration depths and thus are better suited for fluid or single molecule detection. In opposition, interference sensors such as Fabry-PĂ©rots are sensitive to the medium inside their cavity, which can be several tens of micrometers in length, and thus are ideally suited for whole-cell measurement. Still, most of these volume sensors suffer from large LOD or require out-of-plane setups not appropriate for an integrated solution. Such a complex integration of high-throughput, sensitivity and large penetration depth on-chip is an ongoing challenge. Besides, simultaneous characterization of whole-cell RI and deformability has never been reported in the literature

    Performance Enhancement of Building-Integrated Concentrator Photovoltaic System Using Phase Change Materials

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    Building-integrated Concentrator Photovoltaic (BICPV) technology produces noiseless and pollution free electricity at the point of use. With a potential to contribute immensely to the increasing global need for a sustainable and low carbon energy, the primary challenges such as thermal management of the panels are overwhelming. Although significant progress has been made in the solar cell efficiency increase, the concentrator photovoltaic industry has still to go a long way before it becomes competitive and economically viable. Experiencing great losses in their electrical efficiencies at high temperatures that may eventually lead to permanent degradation over time, affects the market potential severely. With a global PV installed capacity of 303 GW, a nominal 10 °C decrease in their average temperatures could theoretically lead to a 5 % electricity efficiency improvement resulting in 15 GW increase in electricity production worldwide. However, due to a gap in the research knowledge concerning the effectiveness of the available passive thermal regulation techniques both individually and working in tandem, this lucrative potential is yet to be realised. The work presented in this thesis has been focussed on incremental performance improvement of BICPV by developing innovative solutions for passive cooling of the low concentrator based BICPV. Passive cooling approaches are selected as they are generally simpler, more cost-effective and considered more reliable than active cooling. Phase Change Materials (PCM) have been considered as the primary means to achieve this. The design, fabrication and the characterisation of four different types of BIPCV-PCM assemblies are described. The experimental investigations were conducted indoors under the standard test conditions. In general, for all the fabricated and assembled BICPV-PCM systems, the electrical power output showed an increase of 2 %-17 % with the use of PCM depending on the PCM type and irradiance. The occurrence of hot spots due to thermal disequilibrium in the PV has been a cause of high degradation rates for the modules. With the use of PCM, a more uniform temperature within the module could be realised, which has the potential to extend the lifetime of the BICPV in the long-term. Consequentially, this may minimise the intensive energy required for the production of the PV cells and mitigate the associated environmental impacts. Following a parallel secondary approach to the challenge, the design of a micro-finned back plate integrated with a PCM containment has been proposed. This containment was 3D printed to save manufacturing costs and time and for reducing the PCM leakage. An organic PCM dispersed with high thermal conductivity nanomaterial was successfully tested. The cost-benefit analysis indicated that the cost per degree temperature reduction (£/°C) with the sole use of micro-fins was the highest at 1.54, followed by micro-fins + PCM at 0.23 and micro-fins + n-PCM at 0.19. The proposed use of PCM and application of micro-finned surfaces for BICPV heat dissipation in combination with PCM and n-PCM is one the novelties reported in this thesis. In addition, an analytical model for the design of BICPV-PCM system has been presented which is the only existing model to date. The results from the assessment of thermal regulation benefits achieved by introducing micro-finning, PCM and n-PCM into BICPV will provide vital information about their applicability in the future. It may also influence the prospects for how low concentration BICPV systems will be manufactured in the future.The financial support provided jointly by Engineering and Physical Science Research Council, UK (EP/J000345/1 and EP/K03619X/1) and Department of Science and Technology (DST), India is greatly acknowledged

    COMPUTATIONAL STUDY OF DROPLET AND CAPSULE FLOW IN CHANNELS WITH INERTIAL EFFECTS

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    The flow of droplets and capsules in channels is important for a variety of industrial and biological applications. Droplet flow is common in microfluidic devices and emulsion processing as well as oil recovery from porous materials. Capsules are used to encapsulate sensitive materials and can be used to study the mechanical properties of biological cells. A computational method was developed to study the two-phase flow of drops with and without surfactants, and capsules surrounded by a thin elastic membrane. This new computational method allowed for the inclusion of inertial effects on droplet and capsule flow which has not received much attention in the past. Results are presented for both the steady flow in straight cylindrical channels, and the transient flow in response to sudden expansions or contractions in the channel diameter. Increasing the Reynolds number was seen to cause non-monotonic trends in the capsule deformation and velocity. Parameters such as the drop viscosity and presence of surfactants were seen to have smaller effects when the Reynolds number became large. Capsules flowing in channels were seen to have limiting elastic capillary numbers above which no stable shape could be found. The transient deformation of drops and capsules moving through expansions depended strongly on the shape of the drop upstream of the expansion. The transient deformation increased with the capillary number up to a limiting value. The flow of droplets through channels was seen to produce large deformations that could break the drop apart at low viscosity ratios. The inclusion of inertial effects caused increases in the transient deformation as well as oscillations as the drops relaxed back into their steady shape

    Metallosupramolecular assemblies : development of novel cyclometalated Pt(II) and Ir(III)-based capsules

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    Inspired by nature’s use of self-assembled systems to carry out virtually all biological processes, chemists have taken to building simplified synthetic systems that mimic the biotic world. Although transition metal-ligand interactions are rarely used for the purpose of biological self-assembly, they have several advantages over other weak noncovalent interactions, such as pronounced directionality and significant strength. These particular attributes have allowed chemists to construct a comprehensive library of self-assembled polygons and polyhedra, using different transition metal-ligand motifs. Many of these supramolecular assemblies possess cavities of defined shape and size, which are able to accommodate guest molecules. It has further been realised that isolation of guest species from the bulk phase can lead to many interesting functions, such as containment, sensing and catalysis. Herein, a new self-assembly strategy has been used to construct novel cyclometalated Pt cages and assembly of the first known [Ir(ppy)2]-based capsule has also been achieved. Chapter 1 includes an introduction to metallosupramolecular assemblies, followed by a comprehensive review of three-dimensional architectures with accessible cavities, their synthetic strategies and applications. Chapter 2 reports on the construction of novel Pt(II)-based trigonal prisms using an unusual, kinetically controlled protocol. By exploiting asymmetric cyclometalated 2-phenylatopyridine based platinum corner units that possess both labile and non-labile cis-coordination sites, trigonal prismatic stereoisomeric architectures have been selectively prepared by altering the sequence of addition of ditopic 4,4â€Č-bipy (4,4â€Č-bipyridine) and tritopic tpt (2,4,6-tris(4-pyridyl)-1,3,5-triazine) molecular structural components using a template free method. Collision-induced-dissociation mass spectrometry experiments were used to differentiate between the structural isomers due to their significantly different fragmentation profiles. Chapter 3 describes the synthesis and characterisation of the first molecular capsule based on an [Ir(ppy)2]+ 90° metallosupramolecular acceptor unit. Initial work focused on pyridine-based donor ligands from which an Ir2L2 metallamacrocycle was assembled. However, when the highly conjugated tpt “panels” were used, due to postulated constraints in the dihedral angle, self-assembly of the Ir6tpt4 octahedral was unsuccessful. The constraints in the dihedral angle were eliminated by swapping pyridine for nitrile-based ligands and following the development of a method to resolve rac-[(Ir(ppy)2Cl)2] into its enantiopure forms, homochiral Ir6tcb4 (tcb = 1,3,5-tricyanobenzene) octahedral capsules where realised. Photophysical studies on the Ircapsules have shown that the ensemble of cooperative, weakly coordinating ligands can lead to luminescence not present in the comparative mononuclear analogues. X-ray crystallographic analysis revealed that the Ir capsules possess cavities large enough to accommodate 4 triflate counterions. Through a series of titration experiments the ability of the capsules to act as anion sensors was also exposed. Further exploration into the host-guest chemistry of the Ir6tcb4 capsule is reported in Chapter 4. Subsequent experiments have shown that self-assembly is highly dependent on the counterions associated with the system. While a number of different anions (OTf-, BF4 -, ClO4 -, PF6 -) facilitate the formation of the same octahedral scaffold, when triflimide was employed as a bulkier counterion, no capsule was observed. On subsequent addition of smaller counterions, such as triflate, the same Ir6tcb4 cage assembles, demonstrating that the anions also act as templates. Kinetic stability experiments, undertook by monitoring the rate of scrambling of the Δ and Λ-[Ir(ppy)2]+ components within the preformed ensembles, show that the Ir capsules are up to 1.4×104 times more stable than their mononuclear analogues. The counter anions were also observed to play a crucial role in the capsule’s stability with measured scrambling half-lives ranging from 4.7 mins with tetrafluoroborate to as long as 4.5 days with triflate. In contrast, the rate of ligand exchange in simple mononuclear complexes, as ascertained using EXSY NMR experiments, was found to be approximately independent of the associated anion
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