2,601 research outputs found

    Simulation-based Optimized Production Policy for Hybrid MTS/MTO Glass Tube Manufacturing Systems

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    Glass Tube is one of the main components for fluorescent lamps as it contains all the other components to generate light. Glass tube industry faces a decline in demand in Egypt. This is attributed to two factors: currency floating and new lighting technologies. In response, glass tube manufacturers decided to diversify their products. This required the integration of Make-to-Stock (MTS), which is used usually for glass tube manufacturing, and Make-to-Order (MTO) which is used to fulfill demands for diversified products. In this thesis, Production policy is proposed to plan for MTS & MTO production. This policy determines when to produce broken glass (cullet), MTS product or MTO product. Priority is given to Cullet which is used as raw material in glass making. The second choice is to produce MTS product, and excess capacity is used to produce MTO products. Once MTO order is fulfilled, the choice is made to either produce cullet or MTS product. The policy defines two levels for cullet inventory and MTS product inventory. If cullet inventory reaches the lower level, cullet will be produced until the inventory level reaches higher level. If the cullet reaches the higher level or the level is decreasing towards lower level, products will be produced. The type of product is determined according to the inventory level of MTS product. If the MTS inventory level is lower than high inventory level, MTS product will be produced. Once it reaches high inventory level, MTO product will be produced. A simulation model is developed to simulate glass tube production. The model is divided into three interconnected modules: production, order fulfillment and decision. The model was verified and validated through different cases. Based on the simulation model, an optimization algorithm is applied to select optimum parameters for proposed policy with the objective of minimizing total costs. The proposed production policy proved its effectiveness in reducing total cost in glass tube manufacturing. Sensitivity analysis was performed to show the effect of raw material prices and energy price on the solutions obtained by optimization algorithm. Increase in raw material prices has effect on production parameters; however, it has no effect policy parameters. Increase in energy prices has effect on production parameters and policy parameters

    Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry

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    [Image: see text] Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry

    Primer Payload System for Higher-Order Multiplex LAMP: Design and Development of Unit Processes

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    Design and Development of Platforms for the Application of Loop-mediated Isothermal Nucleic Acid Amplification, LAMP, in the Diagnosis of Polymicrobial Diseases Tochukwu Dubem Anyaduba, Travis Schlappi (PI) For the past two decades, several isothermal nucleic acid amplification technologies have emerged. These are mostly in response to the need for robust molecular diagnostic tools amenable to point-of-care and limited-resource settings. Of these, loop-mediated isothermal amplification, LAMP, stands out as a highly specific and rapid alternative to the polymerase chain reaction, PCR. One of LAMP\u27s significant characteristics involves using four essential and two loop (rate increasing) primers to recognize six to eight (6 – 8) distinctive regions in a target DNA sequence. While the assortment of primers makes LAMP highly specific, it also poses a challenge to its exploitation in multiplex molecular diagnostics. Several published methods present means of adopting LAMP in multiplexing; however, only very few can detect up to four targets within the same sample stream. Our research\u27s overall goal is to develop platforms capable of exploiting LAMP\u27s high degree of specificity in identifying 9+ pathogens within the same sample stream using rapid prototyping/ simplistic technologies. This goal is fundamental in diagnosing polymicrobial diseases such as urinary tract infections, diarrheal diseases, respiratory tract infections, and other diseases whose attendant symptoms compel uninformed prescriptions. To meet this need, we designed multiple methods and developed unit processes toward achieving a more promising platform, A Primer Payload Platform (P3). The P3 is borne out of the ideology that the isolation of LAMP primer sets and their specific target DNA moieties [AH1] in micro-reaction vesicles from a single reaction mix could aid the differential detection of multiple targets without the limitations attendant to current multiplexing systems. Thus, as a first step toward achieving the P3, we adopted methods for a multifaceted use of beads (as pathogen identity signatures, primer-delivery machinery, and specific target DNA carriers). Secondly, we employed simplistic rapid prototyping methodologies to develop microfluidic cartridges to generate highly monodisperse picoliter-scale droplets. As these droplets are digital-LAMP and digital PCR-ready, we further applied them to detect and quantify Escherichia coli and Lactobacillus acidophilus genomic DNA. Finally, we developed a mechanism for the encapsulation of the beads in picoliter-scale droplets. By unifying the droplet formation and bead introduction rates at the flow-focusing junction, we recorded more single-bead-carrying droplets than predicted by Poisson statistics. While we do not have a perfect system for single-particle encapsulation, we achieved higher single bead encapsulation than ever reported in systems using rapid prototyping for microfluidics or dense bead manipulation. Our vision is to fully integrate these unit processes into a unified microfluidics-based platform for polymicrobial diseases molecular diagnostics at the point of care. We believe this platform will enable timely and precise healthcare interventions within patients\u27 first clinic visits

    Photochemical transformations of quinones under batch and continuous-flow conditions

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    Following green chemistry principles, Madyan Yaseen investigated photochemical transformations of naphthoquinones under batch and continuous–flow conditions. The processes developed offered substantial advantages as they utilized a more selective and practical light source and a safe and low-cost solvent, while at the same time reducing reaction times and product selectivity

    Facile Controlled Preparation of Multifunctional Core-Shell Magnetic Nanoparticles and Their Use in Microfluidic Separation

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    Continuous microfluidic technology has proven to be a potential competitor with established batch systems for facilitating chemical synthesis and purification, and more amenable to miniaturization, integration, and automation. Nevertheless, combining synthesis, purification and analysis remains a challenge due to the lack of development in efficient continuous flow purification techniques. An emerging continuous-flow purification technique is magnetophoresis, which utilizes surface-functionalized magnetic particles to selectively capture target molecules through specific binding, followed by manipulating the migration of particles through external magnetic force. This dissertation explores the synthesis of monodisperse core-shell functionalized magnetic nanoparticles composed of a single-core structure, and their application in magnetic manipulation for capture and isolation of targets in the continuous flow. First, single-cored magnetic nanoparticles with surface functionalities were prepared by coating functional triethoxysilanes onto iron oxide nanoparticles. The morphology, size, and colloidal stability of the resulting functionalized magnetic nanoparticles can be predicted and controlled. Second, a microfluidic device was fabricated from poly(dimethylsiloxane)(PDMS), consisting of two major components, a mixer and a separator (a diagram shown below). In the mixer, target molecules were captured by functionalized magnetic nanoparticles in a T-shape microchannel. Then the magnetic bead-target complex is directed into the separator, where the captured target molecules are magnetically steered out of the matrix while passing through a laminar co-flow profile. For proof of concept, we used a mixture of toluidine blue O (TBO) and sodium fluorescein as a model target and nontarget, respectively, and carboxyl functionalized magnetic beads as a receptor, leading to the selective complexation of TBO and magnetic beads via electrostatic binding. The device allowed for complete separation of the target from the nontarget molecules with high separation selectivity and efficiency as well as excellent reliability and flexibility

    Integrated Vertical Photobioreactor System for Carbon Dioxide Removal Using Phototrophic Microalgae

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    A vertical photobioreactor containing the microalgae Scenedesmus obliquus is a highly efficient system for converting carbon dioxide (CO2) into biomass. The use of photobioreactor for CO2 mitigation has been explored using microalgae as photosynthetic microorganism. The growth rate (m, h-1) were 0.03; 0.13; 0.20; 0.09 at treatment of 0%, 2%, 5% and 7% pure CO2 supplied, respectively during 16 days experiment. The maximum dried biomass (gr ml-1) was 1.7 at 2% pure CO2. The highest CO2 removal effiency (%) was 34 at 2% pure CO2 supply. The results showed that the photobioreactor gave a high efficiency of CO2 removal by phototrophic microalgae culture

    The role of flow in green chemistry and engineering

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    Flow chemistry and continuous processing can offer many ways to make synthesis a more sustainable practice. These technologies help bridge the large gap between academic and industrial settings by often providing a more reproducible, scalable, safe and efficient option for performing chemical reactions. In this review, we use selected examples to demonstrate how continuous methods of synthesis can be greener than batch synthesis on a small and a large scale.Natural Sciences and Engineering Research Council of Canada (NSERC postdoctoral fellowship

    Spectroscopic study on diverse photocatalytic systems for organic transformations

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    The present doctoral dissertation was dedicated to select and develop an integrated photocatalytic system, which can be applied in organic reactions performed at liquid-liquid (homogenous reaction system) or liquid-solid (heterogenous reaction system) interface inside the microfluidic channels. The scientific strategy included (i) examination of potential photocatalysts upon various reaction conditions, (ii) selection of stable photocatalytic system and (iii) its implementation towards flow photochemistry by design an exemplar prototype of microfluidic devices for chemical transformations. Demonstrated strategy consist of consecutive protocols precisely described in subsequent chapters of this thesis. First part of the discussion is concentrated on the selection of photoactive organic molecule, which can act as photocatalyst for further organic transformation. The significant efforts have been made to understand all the factors which affect the formation of stable and efficient photocatalytic system. On that basis, benzothiadiazole derivative compound is proposed as an environmentally friendly photocatalyst applicable in a simple dehalogenation and C-C bond formation reactions of thiophene compounds, as well as in photo-controlled polymerization reaction of methacrylate monomers. Subsequently, to expand the scope of the photoredox catalysis towards flow technologies, the extensive spectroscopic studies on selected photocatalytic system, forming at the liquid-liquid and the solid-liquid interfaces inside the microchannel, were performed. This study allowed to design an exemplar prototype of microfluidic device, which can work upon homogenous and heterogeneous reaction conditions. At the end, the potential application of inorganic photocatalyst towards flow photochemistry is briefly discussed. The ruthenium (Ru(bpy)2CN2) complex with cyanide ligands (CN-) is consider as a potential molecular module that may provide desire architecture of photocatalytic systems, especially under microfluidic conditions due to its self-assembling properties

    A concept for nanoparticle-based photocatalytic treatment of wastewater from textile industry

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    Industrial wastewater, such as the effluents from textile and garment companies, may contain toxic organic pollutants, which resist conventional wastewater treatment. Their complete and environmentally friendly degradation requires innovative technologies. Photocatalysis, an advanced oxidation process, can serve this purpose. Since 1972, when the photocatalytic activity of titanium dioxide was first noticed, photocatalysis has drawn the attention of scientists and engineers but it has not yet been widely applied in industrial practice. This is mainly related to the challenges of up-scaling from laboratory experiments to large production sites. The main goal of this thesis is to develop a concept of nanoparticle-based photocatalysis for the treatment of wastewater. Ideally, process parameters should be adjustable and process conditions should be well-defined. These constraints are prerequisite for establishing process models and comparing the photocatalytic efficiency of different photocatalysts or for different pollutants. More importantly, the configuration should be scalable, in order to cover a wide spectrum of applications. In response to these requirements, this thesis introduces a new reactor concept for photocatalytic wastewater treatment, which relies on finely dispersed photocatalysts as well as uniform and defined process conditions with regard to illumination and flow. The concept was realized in a photocatalytic setup with an illuminated flow reactor. The flow channel has a rectangular cross section and meanders in a plane exposed to two dimensional illumination. Crucial process parameters, e.g., volumetric flow rate and light intensity, can be adjusted in a defined manner. This facilitates the study on the photocatalytic degradation of different organic pollutants in the presence of various photocatalytic materials under arbitrary illumination. The thesis provides a comprehensive description of the operational procedures necessary to run photocatalytic reactions in the experimental setup. It includes three main steps: i) dispersion of photocatalysts, ii) equilibration with respect to pollutant adsorption and iii) accomplishing the photocatalytic reaction. Samples are collected in a mixing tank for online or offline analysis. The proceeding decrease in the concentration of organic pollutant is used to assess the activity of the photocatalytic materials. A particular focus lies on the first of these steps, the dispersion of photocatalysts, because it is ignored in most studies. Typically, photocatalysts are in an aggregated state. The thesis demonstrates that type, intensity and energy of dispersion exert a crucial influence on size and morphology of the photocatalyst particles and, thus, on their optical properties and, accordingly, macroscopic photocatalytic behavior. Apart from this, a proper dispersion is necessary to reduce speed of gravitational solid-liquid separation, at best, to prevent catalyst sedimentation and to avoid misleading results. The photocatalytic performance was intensively investigated for the color removal of a model dye substance, methylene blue. Commercial titanium dioxide nanoparticles, widely explored in literature, were used as a photocatalyst. Their characteristics (size, morphology, stability and optical properties) were determined. Photocatalytic experiments were carried out under UV irradiation. Influences of different factors, including the concentration of the photocatalyst, the concentration of the organic compounds, light intensity, optical pathlength and pH were examined. The degradation was quantified via the decrease of methylene blue concentration. This conversion is, however, an immediate result influenced by all process parameters, e.g., the volume, the light intensity, the optical pathlength. Hence, kinetic models on macroscopic and microscopic levels are established. Normalizations with respect to process conditions are proposed. The apparent reaction kinetics are traced back to volume- and intensity-related reaction rate constants, and the reaction rate constant at the illuminated surface of the reactor. Additionally, the model is modified to be used for time-variant UV intensities, as encountered for solar photocatalysis. These achievements allow for a comparison of the experimental results from different laboratories. Moreover, they are prerequisite for the translation of laboratory results into large scale plants. Selected case studies for further applications are introduced. The photocatalytic degradation of different organic molecules (one antibiotic and two commercial dyes) with different photocatalytic materials (commercial nanomaterials and self-synthesized magnetic particles) under artificial or natural light sources was performed. Additionally, photocatalysis was studied in a realistic application. Preliminary tests with dye solutions of a textile company in Danang, Vietnam, impressively showed the feasibility of wastewater treatment by means of photocatalysis. Based on the reported capacity of wastewater in the current treatment plant of the company, the necessary process parameters were assessed. The rough estimation showed that photocatalysis can improve the working ability of the current wastewater treatment plant. In conclusion, this thesis presents a concept for wastewater treatment by slurry photocatalysis. As the process conditions are adjustable and definable, the process can be ideally performed in laboratories for research purposes, where different materials need to be tested and the working volume can be lower than hundreds of milliliters. The photocatalytic configuration is expected to work with a capacity of hundreds of liters, although appropriate experimental evidences are reserved for further up-scaling studies

    Efficient production of hybrid bio-nanomaterials by continuous microchannel emulsification: Dye-doped SiO2 and Au-PLGA nanoparticles

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    A novel microfluidic system was designed to produce in a continuous manner hybrid nanomaterials using the microchannel double w/o/w emulsification technique. Double w/o/w nanoemulsions were produced combining two inter-digital micromixers that afford working in continuous flow and with a high reproducibility and control on the reaction conditions. High throughput production of two hybrid nanomaterials, dye-doped SiO2 (4 mg/min) and Au-loaded poly(lactic-co-glycolic) acid (PLGA) (168 mg/min) nanoparticles, were achieved, showing the resulting nanomaterials excellent and reproducible optical properties and tunable loading. These hybrid nanomaterials could be potentially used in different biomedical applications. In addition, the microfluidic system designed for carrying out double emulsification enabled to decrease the particle size distribution of dye-doped SiO2 nanoparticles (NPs) up to 20 nm and to improve the Au NPs loading efficiency in Au-loaded PLGA hybrid nanoparticles. The excellent control achieved in the Au NPs loading allowed tuning the payload on demand. Finally, the microfluidic system designed in this work overpasses the productivity described in previously published batch-type reactors, while assuring the same properties of the resulting hybrid nanomaterials
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