A Study Of The Use Of Microelectromechanical Systems

A Study Of The Use Of Microelectromechanical Systems In this paper, microelectromechanical system (MEMS) has been utilized to make miniaturized ion optics required for making the portable all-in-one mass spectrometer. Four different ion optics components were fabricated using deep-reactive ion etching (DRIE) of n-doped silicon-on-insulator. These components are 1 mm Bradbury-Nielsen gate, 500 Â µm coaxial ring ion trap (CRITter), reflectron optics and 500 Â µm Einzel lens. The Bradbury-Nielsen gate was made using a pattern of alternating electrode wires which either allows ions to pass or stop through the gate. The CRITter was made using five trapping rings and two end caps to make mass selection ion optics and it was also used in testing the alignment capability of fabrication process. The reflectron optics was made using a assembly of fifteen rectangular elements arranged in series. The fourth ion optics component was assembled MEMS Einzel lens which consisted of three lenses. It was used to focus the ions beam to increase the ion current and detectability. All the components were tested using ion produced with 70 eV EI ionization. These assemblies were characterized in terms of breakdown voltage, durability, and alignment. For current devices, the breakdown voltage was reported 750 V. The CRITter was tested with 1% toluene at pressure of 1 x 10-4 Torr. The resolution was limited due to the alignment errors and also aberration in etched designs got more impactful as the size of the ion trap was reduced. Current reflectron optics was not capable of resolving the peaks of toluene. Therefore, in the future analyzer path length will be increased by using multiple reflectrons. These miniaturized components were assembled using an encoded piezo-manipulator with pick and place capability. Resolution and ion attenuation was found to be the greatest concern of the current design at present. Fox, J.; Saini, R.; Tsui, K.; Verbeck, G., Microelectromechanical system assembled ion optics: An advance to miniaturization and assembly of electron and ion optics. Review of Scientific Instruments 2009, 80 (9), 093302. In this paper, a soft landing (SL) instrument has been developed with capability of depositing the ions onto the substrate for preparative analysis. The two important components of this instrument are custom made drift tube and two split rings. The drift tube is consist of 18 concentric rings along with two split rings at the end. The drift tube was filled with an inert buffer gas like He and operated from 1 to 100 Torr of pressure. High pressure gas thermalized the cluster ions on collision to 0.01 to 1.0 eV kinetic energy and separate the clusters formed by laser ablation. This helped in further analysis of deposited clusters on mica surface. Two functions of split-ring are to direct the cluster ions towards either detector or a landing surface. This instrument works on the principle of narrowing the kinetic energy of ions going through drift tube to prevent the fragmentation on landing. The gating function of split ring was performed using a homemade pulsing circuit that changes t he voltage across the split ring. The SL instruments was built with a quick door CF flange which reduced the number of gaskets required and helped in holding, adjusting and removing the detector and landing surface from the instrument without disassembling the instrument. A simple Faraday plate was used in SL instrument as detector. A 15 mm mica disk used for atomic force microscopy (AFM) was used as landing surface. Split ring pulsing helped in selecting and isolating the specific ion clusters. For initial experiments copper was used as analyte and it was ionized using laser ablation using ND-YAG laser. Mass spectrum of Copper was reported to have multiple peaks due to Cun+, CunOm+ ions formation in the presence of O2 as contaminant. After the cluster deposition on mica surface, surface was analyzed using AFM and was compared with the physical vapor deposition (PVD). In the future, other landing surfaces like gold, silicon, and highly ordered pyrolytic graphite can be used to bette r understand the deposition mechanism.

How shopping centres and social spaces have changed in terms of Dissertation

How shopping centres and social spaces have changed in terms of architecture and design from 1976-2012 - Dissertation Example This paper discusses that from the perspective of history of art and visual design, the evolution from commercial marketing areas and shopping centres to departmental stores, supermarkets, malls and mega malls, are significant developments since 1976 in Britain. During the time Margaret Thatcher was Prime Minister, 1979-1990, a wide policy of privatization resulted in the establishment of urban development corporations. Control over urban development was seized from local government. This resulted in the widespread privatisation of public space such as the development of shopping centres or malls. According to McGuigan, â€Å"such privatisation of public space erodes urbanity and social cohesion†. During the last few decades, increasing private spaces in public areas have been identified; most are owned by private individuals, organisations and financial institutions; while government-owned space is considered as ‘public’. Privatisation in the public domain is ide ntified in various cases including the emergence of multipurpose shopping centres. Thus, one aspect of privatisation is known as Malling, which reshapes the structure of cities. London’s public spaces and mega shopping malls like Brent Cross in the north-west, Wood Green in the north and Westfield in west London focus on the multidimensional functions that mall culture offers to its clientele. Private developers are aiming to create miniature cities with high quality community space. An extensive variety of shops, services and car parks are provided in these modern interpretations of the High Street. Since they require large areas, they are usually located on the outer suburbs of the city (Grolle 7). Components of the built environment are related to abstract concepts, social relations or ideologies through culturally determined systems of association. They combine to communicate social meaning. The built environment first represents its function, expressing its practical pur pose. Thus, the shopping centre constructed in a wide range of styles â€Å"announces itself through its location and its conventional form as a palace of consumption† (Goss 36). Even the most technologically limited architectural solutions give symbolic expression. The built environment is full of meaning with various nuances; it serves its main objective and also extends beyond its primary function. Thesis Statement: The purpose of this dissertation is to investigate the history and development of the architectural design of London’s shopping centres from Brent Cross to Westfield including other malls like Wood Green, between 1976-2012. British mall culture’s roots in the United States will be identified. The transformations in visual design in malls and social spaces will be examined; and the impact of globalisation, consumerism, fashions, branding, and new product versions will be determined. ADVANCES IN THE DESIGN OF SHOPPING CENTRES AND SOCIAL SPACES FROM BRENT CROSS TO WESTFIELD: 1976 – 2012 Shopping is the most important contemporary social activity, and is mostly carried out in the shopping centre. Developers and designers of the retail built environment exploit the significance of the space to enhance consumption and subsequently ensure the realization of retail profits. They strive to provide other purposes for the shopping centre’s existence, â€Å"manipulate shoppers’ behaviour through the configuration of space, and consciously design a symbolic landscape that induces associative moods and nature in the shopper† (Goss 18). By examining these strategies, it will be possible to gain an understanding of how the retail environment works. â€Å"Brent Cross Shopping Centre and Wood Green Shopping City are both a product of the expansion and large scale investment that occurred in London during the 1970s†

Clandestine labs and the dangers it poses to law enforcement and Essay

Clandestine labs and the dangers it poses to law enforcement and emergency personnel - Essay Example One of the most important growing issues that are provided a particular attention by the US government and US departments on law enforcement is the continuous increase of number of clandestine laboratories in the country. So far, although the government has tried hard to practically create massive definitions on how the law enforcers should actually be involved in handling the situation properly through training and increased competence in the process, it could be seen how the increase of rate in connection with the number of clandestine laboratories in the country today provides a rather different picture on the part of the efforts placed by the national officials on the matter in concern. In this paper, a practical presentation on the issues and particular dangers that both law enforcers and emergency personnel face every time they risk their lives in attacking clandestine laboratories for the sake of protecting the security of the greater population making up the nation. Clandestine laboratories are well known local factories of drug production particularly that of Methamphetamines. These laboratories are noted to be located in hidden areas that are usually kept from the human naked eye due to its being illegal especially in the United States. Many operators of Clan Labs hide their laboratories in places where no one would actually suspect such as garage areas, and other home areas that are not likely much visited by outsiders. However, although placed in such areas, the recognition of these laboratories becomes easy due to the smell of chemicals coming out from the said sources of drug production. Usually, the smell of urine [due to the existence of ammonia] could be recognised from the area of production. An alarming cue that a clan lab may exist in an area should actually give one the right push to tell about the matter to law enforcers who are appointed to oversee the concerned place under the case of a possible clan lab existence. Why is this a must It has been researched and well studied through experience based cases that clan labs are highly dangerous especially for those living within its vicinities. Considerably, the imposed position of the people living around the area is endangered due to the existence of the chemicals that are used for the production of the illegal drugs. These substances are noted to be highly flammable and are also considered dangerous to the health of those who are living around the area where they are used for mass production of drug substances. For this reason, it is highly recommended that community security law enforcers closely see to it that nothing is unnoticeably passed through especially when the issue comes to unknown areas of clan labs hidden within populated communities. Along with that, the aim of protecting the values of the law enforcers appointed for the areas concerned is