Investigation of the Design of a Bistable Micro-Chemical-Mechanical Device Utilizing Lateral Buckling

The Gracias Laboratory at Johns Hopkins University has developed microgrippers which utilize chemically-actuated joints to be used in micro-surgery. These grippers, however, take up to thirty minutes to close fully when activated biochemicals in the human body. This is very problematic and could limit the use of the devices in surgery. It is the goal of this research to develop a gripper that uses theGracias Laboratory\u27s existing joints in conjunction with mechanical components to decrease the closing time. The purpose of including the mechanical components is to induce a state of instability at which time a small perturbation would cause the joint to close fully.The main concept of the research was to use the lateral buckling of a triangular gripper geometry and use a toggle mechanism to decrease the closure time of the device. This would create a snap-action device mimicking the quick closure of a Venus flytrap. All developed geometries were tested using finite element analysis to determine ifloading conditions produced the desired buckled shape. This research examines lateral buckling on the micro-scale and the possibility ofusing this phenomenon in a micro-gripper. Although a final geometry with the required deformed shaped was not found, this document contains suggestions for future geometries that may produce the correct deformed shape. It was determined through this work that in order to obtain the desired deformed shape, polymeric sections need to be added to the geometry. This simplifies the analysis and allows the triangular structure to buckle in the appropriate way due to the added joints. Future work for this project will be completed by undergraduate students at Bucknell University. Fabrication and testing of devices will be done at Johns Hopkins University in the Gracias Laboratory

Growth and characterisation of functional molecular wires

With the miniaturisation of silicon based technology approaching its fundamental physical limit, molecular electronic components are considered an alternative route to prolong the lifetime of integrated circuit technology. In order to realise this technology, the fundamental physical and electronic properties of such nanoscopic materials and devices must be fully understood. This thesis reports the successful formation and characterisation of a series of novel molecular wires on both planar and nanoparticulate surfaces, from which two papers have been published. Formation of these wires was achieved using the reproducible chemical self- assembly method often utilised in bottom-up molecular electronics. After the initial chemisorption of a functional headgroup to a suitable substrate , subsequent layers were chemically reacted by means of an imine bond formation. This allowed multilayer donor-a- bridge-acceptor systems of up to ea. 10.4 nm in length to be constructed. Not only does this method allow the formation of reasonably complex systems, it also enables functionality to be incorporated into the wire. The assembly characteristics of various wires have been characterised using Quartz Crystal Microbalance and X-ray Photoelectron Spectroscopy, and in the case of those on Ti02 nanoparticles, with Infrared Spectroscopy. Furthermore, an investigation into the factors affecting the formation of upright, homogeneous mono layers was carried out on a set of related compounds, revealing the importance of molecule-molecule and molecule-substrate interactions. Multiple molecular wires were also characterised with respect to their electrical properties which show symmetrical or asymmetrical current-voltage curves. This was done using Scanning Tunnelling Spectroscopy to obtain current-voltage characteristics, as well as the so called current jump method to measure single molecule current or that of small clusters of molecules. The effect of increasing molecular length and steric hindrance on molecular current rectification was examined, as well as the effect of increasing length on single molecule conductance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

User Friendly: A Short History of the Graphical User Interface

Susan B. Barnes is an Assistant Professor in the Department of Communication and Media Studies at Fordham University. This paper was presented at Sacred Heart University on November 5, 1995 as part of a symposium on The Implications of New Media Technology sponsored by the Media Studies Department

Exploring the Link Between Customer Care and Brand Reputation in the Age of Social Media

Consumers are more empowered than ever to share their customer care experiences. Through the use of social media and new communications tools and technologies, messages can be sent more widely than ever before. This research study examined the links between social media, customer satisfaction, brand reputation and customer loyalty. The Society for NewCommunications Research designed the research to examine how customer care influences brand reputation given the widespread adoption of social media. Objectives of the research included:To assess the extent to which consumers research and review companies' products/services online prior to making purchase decisionsTo assess the influence of social media on user opinions as they relate to the customer care experienceTo determine what types of online resources and social media are considered the most valuable sources of information about the customer care experienceTo assess the extent to which consumers are influenced by their own customer care experiences and how they think sharing that information online influences how others view products and brands

From Banners to YouTube: Using the Rear-View Mirror to Look at the Future of Internet Advertising

In twelve short years, Internet advertising has evolved from banners to experiential promotions. In the beginning advertisers viewed the Internet in similar ways as they considered traditional media (television, newspaper, magazines). The idea of using a new medium like an older one, was described by McLuhan\u27s concept of the rear view mirror. This article describes the history of Internet advertising from 1994 to 2006 by looking back to understand the future direction of Internet advertising

Plant Ultrastructure in the Scanning Electron Microscope

Preparative techniques which have been used to study internal details of plant cells in the scanning electron microscope are reviewed. A number of methods have previously been described which involve selective extraction of materials from freeze-fractured surfaces and can be referred to as freeze-fracture and cytoplasmic maceration. One of these techniques which involves an extended period of cytoplasmic maceration with dilute osmium tetroxide has been applied to the study of Cichorium intybus (chicory) pollen ontogeny. The results obtained, including changes in the numbers of mitochondria and the form of endoplasmic reticulum during the course of development demonstrate the value of the approach in showing the three dimensional arrangement of organelles and wall layers. The findings emphasise that pollen grains with similar mature morphologies may differ in the details of their ontogeny