Immobilized titanium dioxide for emerging contaminant removal in wastewater

There have been rising concerns about emerging contaminants that are not efficiently removed by conventional wastewater treatment plants. TiO2 photocatalysis is one of the promising routes for sustainable wastewater treatment. Research on the use of TiO2 photocatalysis for water/wastewater treatment for the removal of persistent non-biodegradable emerging water pollutant is active worldwide. Since the mid-1970s the viability of photocatalytic degradation of organic compounds in water using TiO2 was demonstrated. More than 1,000 substances have been degraded using TiO2. Despite the extensive research on photocatalytic oxidation using TiO2, pilot and demonstration plants through the last four decades are still countable. Widespread use of photocatalytic treatment of water and wastewater require the development of an innovative photocatalytic reactor that is efficient, reliable, simple to construct, easy to maintain, has low energy consumption, low capital and operating cost and provides easy separation of catalyst after treatment ends. In an attempt to develop this desired photo-reactor, three photo-reactors were designed and constructed: the slurry water-bell photo-reactor, the immobilized water-bell photo-reactor and the immobilized tray photo-reactor. The slurry water-bell photo-reactor is based on generating a thin water film to allow for solar light penetration for photo-catalyst activation and continuous oxygenation. Recirculating the reaction solution at a high flow rate ensures good mixing and avoids dead zones in the photo-reactor. the reactor performance for degradation of phenol, as a model compound, was evaluated using commercial TiO2. Factors affecting the degradation efficiency were studied including catalyst loading, light intensity, initial pollutant concentration, oxidant addition and exposure time. Dissolved oxygen levels, temperature and pH were monitored through all the conducted tests. The performance of the slurry water-bell was compared with other photo-reactors using two benchmarks: the degradation rate constant and the reactor throughput. The reactor throughput is a function of the treated volume, treatment duration and reactor area footprint, thus it is as a versatile indicator for comparison between reactors of different types and geometries as well as selection of reactor configurations suitable for scale-up and commercialization. TiO2 was immobilized on sand grains for use as dispersed photo-catalyst in the water-bell reactor. Immobilization of TiO2 was conducted by two methods; direct immobilization using sol-gel synthesis and binding with epoxy coating. Photo-catalyst abrasion was encountered. The strong mixing conditions and flow through the recirculating pump resulted in high abrasion of the photo-catalyst off the sand surface. The tray photo-reactor was developed to avoid the high friction of the photo-catalyst particles in the recirculating pump while maintain fulfilling all the other photocatalytic process requirements of light penetration, continuous oxygen supply, and turbulent flow. The immobilized tray photocatalytic reactor uses a fixed-bed of TiO2 supported on sand grains. The reactor maintains a thin water film over the supported TiO2 catalytic bed. TiO2 was immobilized on the sand grains using 3 different immobilization approaches: 1) direct immobilization using the sol gel technique, 2) coating with TiO2/cement grout; and (3) binding with TiO2-epoxy coating. Reactor performance for the degradation of phenol as a model compound was evaluated for the three photo-catalysts. Immobilization of TiO2 on sand particles using epoxy was successful in achieving the highest phenol degradation and resistance to abrasion. The water turbidity remained unchanged indicating photo-catalyst resistance to abrasion even after multiple use of the catalytic bed. Successful operation of the tray photo-reactor in the continuous mode was also achieved. The performance of the immobilized tray photo-reactor was compared with other photo-reactors using three benchmarks: the initial degradation rate, the reactor throughput and turbidity. The immobilized tray photo-reactor is suitable for scale-up and commercialization due to five distinctive features which are: modular design; integrated storage; passive oxygenation; absence of need for UV transmitting components that are susceptible to breakage and optical losses, and simple and cheap components

Prediction of tip vortex cavitation inception on marine propellers at an early design stage

The inception of vortex cavitation at an early design stage is still difficult to forecast. The most reliable prediction of the full scale performance is achieved by means of model tests, which are possible for few designs only. A simplified model to calculate the inception of tip vortex cavitation is developed and tested. The model is based on results obtained from potential flow theory, using a boundary element method. The developed tip vortex cavitation inception model and also the panel method are described, after a short introduction to vortex cavitation. The numerical behaviour of the model is investigated for an elliptic wing at different angles of attack and two marine propellers in homogenous and not axially symmetric inflow. The cavitation model s properties concerning different Reynolds numbers are studied and the scale effects on calculated model- and full-scale tip vortices are discussed.http://deepblue.lib.umich.edu/bitstream/2027.42/84317/1/CAV2009-final143.pd

The factors which affect the information system needs for decision making in the hotel industry (A comparison study between the U. K. and Egypt)

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This report contains evidence to show that the information provided by computers in the hotel industry, for the management work & decision making, has not changed too much since 1970. In most industries, the successful computer applications are clearly noticed in the routine work (clerical jobs) more than the management work (strategic & tactical jobs). As for the hotel industry the use of computers still comes at the back of the list. The hospitality characteristic of hotel work is the main reason why people and not machines are used Small hotels are different from large luxury hotels in using computers, mainly for economic reasons. Top managers are different from lower managers in using computers, simply for technical reasons (lack of management computer programmes). The British hotels are different from Egyptian hotels in applying computers and information technology successfully for reasons related to the influence of the managerial environment in each country. A comparison between hotels of the two countries shows the unsatisfaction of the hotel managers about the information they receive from their computer departments. The analysis of the management work, the identification of the decision making needs are still hard tasks for system analysts. The identification of both the managers' decisions & information needs is still not recognized, even by the managers themselves. The decision making approach is used in this study to identify both the managers' decisions & information needs and to evaluate the information systems available in the hotels of the two countries. The managerial environment of the country greatly influences the managers' decisions and system needs. This report outlines the background literature & approaches used to research this area. Use is made of the results of previous study done about Egyptian hotel industry and the factors which affect the success of the information systems there. Investigational work for the influence of the managerial environment in Egypt, over the structure of the marketing decision making process in the hotel industry is carried out. Areas for further ‘field’ research studies are highlighted.Ministry of Higher Education and Scientific Research of Egyp

The Insecticidal Activity of Tea Tree Oil (Melaleuca Alternifolia) Against the Common Pest in Mummies (Dermestes Maculatus)

Egyptian mummies show different signs of deterioration caused by insects, such as missing parts, gaps and accumulated dust. Dermestes maculatus is one of the serious pests that cause damage to Egyptian mummies. To assess the insecticidal activity of tea tree oil against the larvae of the museum insect pest Dermestes maculatus (isolated from Egyptian mummies) we tested it under different concentration and treatment times by the bioassay methods. Our results showed that tea tree oil diluted in ethanol was highly toxic to Dermestes maculatus larvae. Insecticidal activity depended on both concentration and exposure time. By increasing the concentration level and the exposure time we obtained a higher mortality rate

Integrity of financial information and firms\u27 access to energy in developing countries

© 2020 There are strong international pressures on developing countries to achieve the universal energy access 2030 goal and to establish stricter monitoring mechanisms of firms\u27 financial information to attract energy investment. We argue that energy access is both a technical and an economic issue, and hence the integrity of firms\u27 financial information is a key monitoring mechanism. We analyze the impact of financial information integrity on firms\u27 access to energy in 138 developing countries. Our results show that the integrity of financial information is a robust predictor of firm\u27s access to energy. The decision of a firm to have its financial accounts externally audited is associated with a higher probability of better access to energy. The effect depends on country size, but not country development. Other important aspects of business operation, such as financing and corruption, also affect energy access. The financial information integrity effect on energy access depends on the firm\u27s size, industry and geographical location. Country-level macroeconomic, auditing and energy infrastructure conditions play a role too. Economic and financial development, economic openness, the accounting and auditing environment and the technical conditions of energy generation in a country are important controlling factors of the financial information integrity effect. Policy considerations in the developing world aiming at improving firms\u27 access to energy must pay attention to the role of external monitoring mechanisms and the conditions that induce firms to embrace higher level and quality of external auditing

Flow study on a ducted azimuth thruster

This paper presents the results of the numerical validation and verification studies on an azimuth thruster. The numerical investigations include a grid study as well as an analysis of the simulation results obtained by different isotropic an anisotropic turbulence models, such as k-omega, SST, SAS-SST, BSL-EARSM and DES. The numerical simulation results of selected flow conditions are compared with experimental data. To investigate scale effects on the open water results numerical computations are carried out for a thruster in full- and model scale and the calculated thrust and torque coefficients are compared with model scale simulations and measurements

Time domain simulation of dynamic positioning manoeuvres based on impulse response functions

The Paper focusses on the development of a numerical method to simulate ship motions under arbitrary external forces. Based on impulse response functions, the de- veloped method benefits from the computational efficiency of boundary element methods in frequency domain to determine hydrodynamic forces acting on the vessel. Major non- linear effects are captured directly in time domain. To capture the vessels drift motion, second-order wave excitation is considered. Wind and current induced forces complete the modelling of environmental loads. An interface to MATLAB/SIMULINK simplifies an efficient representation of the vessels control system and the dynamics of its propul- sion plant. This finally allows time-domain simulations of complex dynamic positioning manoeuvres in natural seaway

Minimal Invasive Chirurgie der Zehengelenke mit Hilfe der C-Bogen Technik

Deckblatt-Impressum persönlicher Dank Contents Abbreviations Introduction Review of literature Materials and methods Results Discussion Conclusions Summary Zusammenfassung References Acknowledgment SelbständigkeitserklärungThis study was carried out on 140 horses of different sexes, ages and breeds which were admitted to the Equine Clinic at the Free University, Berlin between January 2000 and May 2004. A total of 158 phalangeal joints underwent successful fluoroscopic guided minimal invasive surgery using the mobile C-arm fluoroscope (Philips BV212 Rlease 4). The indications in all horses were: 1-Surgical removal of isolated shadows (radiopaque bodies) from the region of the common digital extensor tendon insertion at the extensor process of the pedal bone (28 horses). 2- Surgical removal of isolated shadows (radiopaque bodies) from the dorsal aspect of the pastern (3 horses). 3-Surgical removal of isolated shadows (radiopaque bodies) from the dorsal or the palmar/plantar aspect of the fetlock joint (76 horses). 4-Surgical repair of intra-articular fractures associated with the phalangeal joints (25 horses). 5-Surgical managements of subchondral bone cysts (8 horses). All personnel in the operating room wore standard radioprotective aprons and every one had a portable dosimeter. Each surgeon wore an additional ring dosimeter. At monthly intervals, the radiation doses were measured for every one in mSv and were very low and did not exceed the legal limits permitted in Germany. From the technical point of view all the operations were easily performed and no intraoperative complications encountered. In equine orthopedic surgery, minimal invasive techniques should be more applied to improve wound healing by a minimal access and consequently to shorten the convalescence period. Phalangeal joints are from the joints that can be successfully operated with the aid of fluoroscopic guided C-arm technique as a minimal invasive technique. The possibility now exists to operate these joints only under fluoroscopic control which constitutes a further step in the replacement of arthroscopy and arthrotomy techniques by fluoroscopy (especially in case of the small joints or in case of isolated shadows which located in the joint vicinity and are embedded or buried within the joint capsule, tendons or ligaments). The use of a combination of fluoroscopy and arthroscopy techniques is also possible. Fluoroscopic guide C-arm technique is practical from the technical and cosmetic point of view. The technique is not sophisticated, quick, and easy to perform. Following fluoroscopic guided surgery the cosmetic appearance was improved and the convalescent time decreased.Diese Studie wurde an 140 Pferden mit unterschiedlichem Geschlecht, Alter und Rasse, die im Zeitraum Januar 2000 bis Mai 2004 in der Klinik für Pferde der Freien Universität vorgestellt wurden, durchgeführt. Insgesamt wurden 158 Zehnengelenke mittels minimalinvasiver Chirurgie und unter Durchleuchtungkontrolle mit einer C- förmigen Bogen (Philips BV212 Release 4) operiert. Die Indikationen bei allen Pferden waren: 1-Chirurgische Entfernung der isolierten Verschattung aus dem Bereich des Prozessus extensorius (28 Pferde). 2- Chirurgische Entfernung der isolierten Verschattung aus der dorsalen Gelenkaussackung des Kronglenkes (3 Pferde). 3- Chirurgische Entfernung der isolierten Verschattung aus dem dorsalen oder palmaren/ plantaren Bereich des Fesselgelenks (76 Pferde). 4- Interne Fragmentfixation (Osteosynthese) von intraartikulären Frakturen der Zehengelenke (25 Pferde). 5- Chirurgische Behandlung zystoider Knochendefekte (8 Pferde). Alle beteiligten Personen im Operationssaal waren mit Röntgenschürzen und Dosimeter ausgestattet. Die Chirurgen trugen zusätzlich Fingerring Dosimeter. Die Dosimeter wurden in monatlichen Intervallen ausgewertet und die gemessene Werte (mSv) übersteigen in keinen Fall die zugelassenen Normalwerte. Aus technischer Sicht waren alle Operationen einfach durchzuführen und es kam zu keinen intraoperativen Komplikationen. In der Pferdeorthopädie sollte die minimalinvasive Technik mehr eingesetzt werden, um die Wundheilung zu verbessern und die Rekonvaleszenzzeit zu verkürzen. Die Zehenengelenke können mit dem Einsatz des C-Bogens erfolgreich minimalinvasiv operiert werden. Diese Operationtechnik mit C-Bogen Kontrolle kann als Ersatz einer Arthroskopie oder Arthrotomie-Technik eingesetzt werden (besonders in Fällen bei kleinen Gelenken oder im Fall von isoliertem Verschattungen, die außerhalb des Gelenkes, in der Gelenkkapselwand, in Sehnen oder in Bänden eingebaut sein können). Der Einsatz von Kombinationen mit C-Bogen und Arthroskopie-Technik ist ebenfalles vorteilhaft. Die Durchleuchtungskontrolle mit dem C-Bogen ist aus technischen und kosmetischen Gesichtpunkt praktisch. Die Technik ist hoch entwickelt, schnell, und einfach durchzuführen

Study of New Miniaturized Microwave Devices based on Ratchet Effect in an Environment of Asymmetric Nano-Scatterers

La nanotechnologie est un domaine en voie d’expansion qui a attiré l’attention de la recherche en raison de ses applications potentielles illimitées. La technologie des ondes millimétriques est un autre domaine intéressant qui joue un rôle de premier plan dans le développement des systèmes de communications sans fil. La combinaison de ces deux champs de recherche avancée, donne naissance à l’innovation du Dispositif Ratchet qui est une nouvelle application qui représente un vrai défi. Ce dispositif est de taille nanométrique et son concept d’opération consiste à générer une tension DC lorsque le dispositif, basé sur le gaz d’électron bidimensionnel, est rayonné par l’énergie des micro-ondes. L’objectif de cette thèse est d’essayer d’améliorer la réponse du dispositif, ce qui ouvre de nouvelles perspectives dans la fabrication des détecteurs de champ à haute fréquence et à l’échelle nanométrique. Malheureusement, les Dispositifs Ratchet actuels, basés sur des hétérostructures de semiconducteurs, réalisés jusqu’à présent fonctionnent à basse température pour assurer une grande mobilité électronique. Cette condition nécessite l’utilisation d’un setup expérimental complexe qui a un grand impact sur la tension induite et sur la reproductibilité du phénomène Ratchet observé. Dans ce contexte, le travail effectué dans le cadre de cette thèse a abordé ce problème en deux parties. La première partie concerne l’analyse électromagnétique du setup expérimental. Ceci a été réalisé par la mise en oeuvre des simulations électromagnétiques intenses. D’autre part, différentes solutions ont été proposées afin d’optimiser le setup et ainsi améliorer la tension Ratchet produite. Outre l’étude électromagnétique, certaines mesures de modulation ont été réalisées pour tester la faisabilité du Dispositif Ratchet comme un démodulateur d’amplitude. La deuxième partie de cette thèse traite l’étude de la matière qui compose le Dispositif Ratchet. Récemment, le graphène commence à envahir le monde scientifique et technologique avec ses fascinantes propriétés électroniques, tels que sa mobilité d’électrons élevée à température ambiante, où les matériaux conventionnels sont en train de confronter des obstacles. En conséquence, l’idée de fabriquer un Dispositif Ratchet à base de graphène au lieu des hétérojonctions de semiconducteurs, a été introduite. Plusieurs modèles de conception, caractérisation et mesures RF ont été accomplis en vue d’obtenir un Dispositif Ratchet fiable approprié pour de nombreuses applications pratiques à la température ambiante, dans la gamme de fréquences micro-ondes et pourraient s’étendre à la bande térahertz. ABSTRACT : Nanotechnology is a growing field that has attracted significant research attention due to its unlimited potential applications. Millimeter wave technology is another interesting field that plays a leading role in the development of wireless communications systems. Combining these two advanced research fields together, has given rise to the innovation of the Ratchet Device which is now a new challenging application. This device has a nanoscale size and its concept of operation consists of generating a DC voltage when radiating a two-dimensional electron gas based device with microwave energy. The aim of this thesis is in trying to improve the device response and hence opening new perspectives in the fabrication of high frequency field detectors on the nanoscale level. Unfortunately, the current Ratchet Devices, based on semiconductor heterostructures, realized till now, operate at low temperatures to ensure high electron mobility. This condition necessitates the use of a complex experimental setup that has a great impact on the induced voltage and on the reproducibility of the observed Ratchet phenomenon. In this context, the work performed within the framework of this thesis has addressed this problem in two parts. The first part concerns the electromagnetic analysis of the experimental setup behavior. This has been achieved by implementing intensive full wave electromagnetic simulations. Different solutions have been proposed to optimize the setup and thus enhance the Ratchet voltage produced. In addition to the electromagnetic study, some modulation measurements have been performed to test the feasibility of the Ratchet Device as an amplitude demodulator. The second part of this thesis deals with the study of the material composing the Ratchet Device. Recently, graphene has started to invade the scientific and the technological world with its fascinating electronic properties, such as its high electron mobility at room temperature, which distinguishes it from conventional materials that typically collide with obstacles. As a result, the idea of fabricating a Ratchet Device based on graphene instead of semiconductor heterojunctions has been introduced. Several design models, characterizations and RF measurements have been performed in order to obtain a reliable Ratchet Device suitable for many practical applications at room temperature. This has been done in the microwave frequency range and can also extend to the terahertz band