Crown Ether-Modified Clays and their Polystyrene Nanocomposites

Crown ether-modified clays were obtained by the combination of sodium and potassium clays with crown ethers and cryptands. Polystyrene nanocomposites were prepared by bulk polymerization in the presence of these clays. The structures of nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. Their thermal stability and flame retardancy were measured by thermogravimetric analysis and cone calorimetry, respectively. Nanocomposites can be formed only from the potassium clays; apparently the sodium clays are not sufficiently organophilic to enable nanocomposite formation. The onset temperature of the degradation is higher for the nanocomposites compared to virgin polystyrene, and the peak heat release rate is decreased by 25% to 30%

Rapid rotation of micron and submicron dielectric particles measured using optical tweezers

We demonstrate the use of a laser trap (‘optical tweezers’) and back-focal-plane position detector to measure rapid rotation in aqueous solution of single particles with sizes in the vicinity of 1 μm. Two types of rotation were measured: electrorotation of polystyrene microspheres and rotation of the flagellar motor of the bacterium Vibrio alginolyticus. In both cases, speeds in excess of 1000 Hz (rev s−1) were measured. Polystyrene beads of diameter about 1 μm labelled with smaller beads were held at the centre of a microelectrode array by the optical tweezers. Electrorotation of the labelled beads was induced by applying a rotating electric field to the solution using microelectrodes. Electrorotation spectra were obtained by varying the frequency of the applied field and analysed to obtain the surface conductance of the beads. Single cells of V. alginolyticus were trapped and rotation of the polar sodium-driven flagellar motor was measured. Cells rotated more rapidly in media containing higher concentrations of Na+, and photodamage caused by the trap was considerably less when the suspending medium did not contain oxygen. The technique allows single-speed measurements to be made in less than a second and separate particles can be measured at a rate of several per minute

Millimeter-Wave MMICs and Applications

As device technology improves, interest in the millimeter-wave band grows. Wireless communication systems migrate to higher frequencies, millimeter-wave radars and passive sensors find new solid-state implementations that promise improved performance, and entirely new applications in the millimeter-wave band become feasible. The circuit or system designer is faced with a new and unique set of challenges and constraints to deal with in order to use this portion of the spectrum successfully. In particular, the advantages of monolithic integration become increasingly important. This thesis presents many new developments in Monolithic Millimeter-Wave Integrated Circuits (MMICs), both the chips themselves and systems that use them. It begins with an overview of the various applications of millimeter waves, including a discussion of specific projects that the author is involved in and why many of them demand a MMIC implementation. In the subsequent chapters, new MMIC chips are described in detail, as is the role they play in real-world projects. Multi-chip modules are also presented with specific attention given to the practical details of MMIC packaging and multi-chip integration. The thesis concludes with a summary of the works presented thus far and their overall impact on the field of millimeter-wave engineering.</p

Daubert and the Quest for Value-Free Scientific Knowledge in the Courtroom

In a world that grows more technologically complex every day and in which scientific research continually expands both our understanding of, and our questions about, the operation of the natural and man-made world, it is hardly surprising that science should show up with increasing frequency in our court-rooms. Science itself is sometimes at issue, for example, in proceedings on allegations of scientific misconduct or in disputes over the ownership or patentability of technologies. But more frequently, science enters in aid of resolving a case in which a complex question of causation is at issue. To establish or rebut causation, each side may seek to introduce evidence from expert witnesses. With crowded dockets, the simpler cases are more likely to settle, while more complex ones-especially class actions and mass tort suits-go to trial, which may explain why in some jurisdictions, experts take part in upwards of eighty percent of all trials

Job Insecurity Across Borders: An Examination of Job Insecurity, Perceived Organizational Support, and Turnover Intentions in the United States and China

Job insecurity is growing around the world, with employees staying at their jobs for shorter durations and part-time, contract, and even extremely short-term “gig” work becoming increasingly common. Job insecurity has been linked with several undesirable outcomes for both the individual and the organization, such as higher levels of employee burnout and increased turnover. This thesis seeks to extend the job insecurity literature by treating job insecurity as a demand within the Job Demands-Resources model, with perceived organizational support (POS) as its resource opposite. In addition, I utilized data collected in both the United States and China, providing insights into how job insecurity’s effects may differ cross-culturally. Results from this study showed that job insecurity had a direct relationship with turnover intentions in the Chinese sample and POS had a direct relationship in the American sample, suggesting cultural differences do exist regarding experiences of job insecurity. Implications for future research and practice are also discussed