Pulsed laser deposition of Bismuth Telluride compounds for human body energy scavengers

The world wide research interest in Bismuth Telluride thin films is due to the fact that they are the most commonly efficient thermoelectric materials at temperatures as low as room temperature, which is typically suitable for implementing such thin films through the fabrication of miniaturized thermoelectric generators and human body energy scavengers. This work aims to characterize various Bismuth Telluride -based thin films deposited by Pulsed Laser Deposition technique in order to optimize their thermoelectric performance represented in their thermoelectric figures of merit. This has been achieved by investigating the electrical and thermoelectric properties of the deposited thin films as well as studying the structural properties of such thin films that is necessary for future micromachining and fabrication of energy scavengers; the results of this effort are really promising. The first chapter is an introductory overview concerning thermoelectric effects and thermoelectric generators. The second chapter deals with the different deposition techniques and the reasoning behind the employment of PLD to deposit Bismuth Telluride thin films. The third chapter includes some of Bismuth Telluride chemical and physical properties in addition to a literature survey of what other groups have already achieved concerning this material. The fourth chapter covers all the experiments and includes the results of this work. Finally, the fifth chapter includes the summary, conclusion and recommendation for future progress in this topic

Caravan trade and routes in the northern Sudan in the 19th century: a study in historical geography

Trade is an important aspect of the economic geography of any country and during the 19th century trade in the Sudan laboured under peculiar difficulties. A harsh physical environment, presenting many difficulties, not least the absence of water, was associated with economic backwardness and political unrest. Thus in the 19th century trade was still limited to certain basic natural products, such as gum and ivory which had been articles of trade from earliest times . Further development was curtailed by a scarcity of capital, the absence of a standard currency, heavy and arbitrary taxation associated with administrative incompetence and short-sighted monopolistic policies. Underlying many of these problems was the absence of a cheap and efficient means of transport. As a result of physical barriers along the Nile in form of cataracts, trade routes were forced to cross barren deserts and hence the only mode of transport available was the camel. Slow and temperamental, this beast possessed only a limited carrying capacity and this fact, together with the nature of the routes followed, to a great extent determined the type of articles which could be transported. All fragile and bulky goods were necessarily excluded, and for export, traders of necessity concentrated an those products with a high value per unit weight, such as perfumes, spices and cotton goods. In addition to this trade in high value materials there was internal trade consisting mainly of provisions dealing which tended to be seasonally variable and relatively localised. Throughout the 19th century in an attempt to stimulate trade successive governments resorted to various schemes, attempting to improve communications and develop agricultural resources so as to diversify the articles available for export. These were some short-term successes but in general most of these attempts were a failure because of a singular lack of overall economic planning and the high cost and inadequacy of transport

Commercial cotton growing in the Sudan between 1860 and 1925: a study in historical geography

Commercial cotton production was introduced into the Sudan on two distinct and separate occasions, by the Turks in the 1860's and by the British in the 1900's. The earlier venture, however, was a total failure while the second was a success. This thesis examines the factors underlying failure and success using the records left by travellers, administrators and agriculturalists to discuss and evaluate man's changing attitude to the agricultural resources of the Sudan between the years 1860 and 1925. The thesis, a contribution to the historical geography of an African underdeveloped country in the colonial period, stresses the importance in development schemes of two factors, first, the need for careful, soundly conceived and sympathetic pilot studies prior to the main scheme, drawing as much as possible on indigenous farming practice, and second, the need for a clear view of the ultimate aims of large scale developments as an essential preliminary to the isolation of salient issues and the implementation of a consistent policy. In retrospect it can be seen that the Gezira Scheme proper has been a. great success and this study focuses upon the vital antecedents that made it a success

Well Control in Drilling Process

Kicks represent the most dangerous situations that could happen while drilling a well, since it can easily develop into a serious blowout.Well control is one of the important issues because improper well control will lead to a blowout which is the most feared operational hazards and expensive cost. Wells are not only drilled vertically or deviated nowadays but also horizontally and adding up extended reaches wells (ERD) for economical and technical reasons. For this study, the project focused on well control in ERD well by using Halliburton.s software, WELLPLAN. WELLPAN is very useful software which is provides various functionalities such as torque drag analysis, analyze hydraulics, analyze surge/swab pressures and ECD.s, investigate well control and etc. This project is focused on investigate well control using the Well Control Analysis Module. The Well Control module can be used to determined predicted kick type, estimate influx volume and kick tolerance, evaluate pressure and generate kill sheet

MEMS Switches Implemented in Different Technologies for RF Applications

Microfabrication technologies allow building micro-scale and nano-scale mechanical switches. Despite the fact that the solid-state switches exhibit superior performance as compared to their micro-mechanical competitors in terms of speed and lifetime, mechanical switches exhibit various attractive features such as low power consumption, high linearity, high isolation and low loss. This work summarizes the design, fabrication and testing of several micro-mechanical switches for Radio Frequency (RF) applications and using different microelectromechanical systems (MEMS) technologies. The implementation is carried out through four approaches for realizing MEMS switches. In the first approach, the switches are built by post-processing chips fabricated in a standard complementary metal-oxide semiconductor (CMOS) fabrication process. The structural layers of the electrostatic MEMS switches are implemented in the four metal layers of the back end of line (BEOL) in the standard CMOS 0.35µm process. In addition, an enhanced post-processing technique is developed and implemented successfully. The switches presented include a compact 4-bit capacitor bank, a compact 4-bit phase shifter / delay line, a W-band single pole single through (SPST) series capacitive switch, SPST shunt capacitive switches with enhanced capacitance density, and a proposed compact T-switch cell with metal-to-metal contact switches. In the second approach, a standard multi-user MEMS process is implemented. Electrothermal and electrostatic MEMS switches designed, fabricated and tested for low-frequency high-power RF applications using the MetalMUMPs process. The devices include a 3-bit capacitor bank, a compact discrete capacitor bank that can be configured for 2-bit / 3-bit operation depending on the stroke of the electrothermal actuators, and a novel rotor-based electrostatic multi-port switch. In the third approach, an in-house university-based microfabrication process is developed in order to build reliable MEMS switches. The UWMEMS process, which was developed at the Center for Integrated RF Engineering (CIRFE), is used in this research to fabricate novel switch configurations. Moreover, the capabilities of the standard UWMEMS process are further expanded in order to allow for building geometric confinement (GC) or anchorless switches and other novel switches. The gold-based UWMEMS switches presented include compact T-switches, R-switches and C-switches, GC SPST shunt and series switches. Additionally, other novel switch architectures such as the hybrid self-actuation switch (HSAS) and thermally-restored switches (TRS). In the fourth approach, which is a hybrid approach between the first and third approaches, the MEMS switches are built and packaged in one fabrication process, and without the need for sacrificial layer, by means of a wafer-level packaging technique. Adopting silicon wafers for the microfabrication necessitates using silicon-core switching, which offers few attractive advantages as compared to the metal-based switches implemented by the third approach. The designed switches to be fabricated in a state-of-the-art industrial facility include a variety of simple SPST contact-type switches as well as compact designs of T-switch, C-switch, a novel four-port gimbal-based switch (G-switch) introduced in this work, SP4T cells, and a seesaw push-pull SPST switch design is included

Synthesis, spectral characterization, antimicrobial, DNA binding and antioxidant studies of Co(II), Ni(II), Cu(II) and Zn(II) metal complexes of novel thiosalen analog N2S2

Co(II), Ni(II), Cu(II) and Zn(II) metal complexes of a quadridentate Schiff base with a N2S2 donor set derived from condensation of benzene-1,2-dicarboxaldehyde(o-phthaldehyde) with 2-aminothiophenol were synthesized and characterized by elemental microanalyses, molar conductance, magnetic susceptibility measurements and spectroscopic techniques viz, FT-IR, 1H NMR, EPR and UV-Vis. The spectral data showed that, the ligand acts as a tetradentate ligand and the bonding sites were deprotonated thiol-S groups and azomethine nitrogen atoms. The results have indicated that the complexes exhibited tetrahedral geometry arrangements except Cu(II) complex that exhibited square planar geometry. Preliminary antimicrobial screening shows the promising results against both bacterial and fungal strains. The interaction of the Schiff base ligand and its complexes with calf-thymus DNA (CT-DNA) has been monitored by UV-Vis, competitive fluorescence titration and hydrodynamic techniques (Viscosity measurements). The results have indicated that the ligand and its complexes bind to CT-DNA through intercalation mode. Moreover, investigations of antioxidative properties showed that all the compounds have strong radical scavenging properties. The data have shown that, among all compounds, Cu(II) complex has exhibited better biological activity than other complexes and the parent ligand

Modulation of macrophage functions by sheeppox virus provides clues to understand interaction of the virus with host immune system

BACKGROUND: Poxviruses encode a range of immunomodulatory genes to subvert or evade the challenges posed by the innate and adaptive immune responses. However, the inactivated poxviruses possessed immunostimulating capacity and were used as a prophylactic or metaphylactic application that efficiently reduced susceptibility to infectious diseases in different species. This fact is intensively studied in different genera of poxviruses. However, little is known about the basic mechanisms adopted by sheeppox virus (SPPV). SPPV causes an acute disease of sheep that recently, has been observed to reinfect its host in spite of vaccination. RESULTS: By injecting inactivated or attenuated sheeppox virus SPPV vaccine in adult male Swiss mice, SPPV was found to reduce macrophages' functions in a local event that occurs at the site of application 12 h after vaccine administration as indicated by increased level of IL-10 and decreased level of SOD from cultured peritoneal macrophages. In contrast increased levels of IL-12, and SOD activity from cultured splenic macrophages, lymphocyte response to PHA-P, and in-vivo response to T-dependant Ag were detected. These effects were observed in both attenuated and inactivated SPPV, but more prominent in attenuated one. CONCLUSION: The results of this study help to elucidate, the phenomenon of existence natural SPPV infections in sheep instead of vaccination and the basic mechanisms responsible for the immunostimulating capacity of sheeppox virus. Locally, SPPV shows evidence for an immune escape mechanism that alleviates the host's immune response. Later and systemically, the virus protects the host from any fatal consequences of the immune system suppression

Stability of Vitamin C in Tomato Juice

Author Institution: Department of Agricultural Industries, Faculty of Agriculture, Cairo University, Giza, Egyp