Impedance-type measurements using XPS

Cataloged from PDF version of article.An impedance type of measurement using X-ray photoelectron spectroscopy is applied for probing charging/discharging dynamics of a sample containing Rb deposited on a SiO(2)/Si substrate containing an octadecyltrichlorosilane (OTS) bilayer coating. The OTS bilayer coatings have possible use as anti-relaxation wall coatings for alkali atom vapor cells in miniaturized instruments such as chip-scale atomic clocks, and/or magnetometers. The measurement consists of the application of bipolar square wave pulses of +/- 10.0 V amplitude to the sample with varying frequencies in the range of 10(-2) to 10(2) Hz while recording X-ray photoemission data. For a conducting sample this type of measurement twins all the photoemission peaks at -10.0 and +10.0 eV positions at all frequencies with exactly 20.0 eV difference between them. However, for samples amenable to charging, the difference between the twinned peaks is less than 20.0 eV, and gradually decreases at correspondingly lower frequencies. For the sample under consideration here at 0.01 Hz, the twinned O1s and Si2p peaks, representing the SiO(2) substrate, are separated by 18.2 eV, displaying a 1.8 eV charging shift. These positions differ from those of the C1s (18.0 eV) representing the OTS bilayer and the Rb3d peaks (18.1 eV). These results reveal that the Rb is electrically (perhaps also chemically) isolated from the OTS bilayer, which may be correlated with the improved performance of the OTS bilayers as anti-relaxation coatings in these alkali atom magnetometer cells. (C) 2009 Elsevier B. V. All rights reserved

A short-term multicenter analysis of radiolucent lines in a single uncemented rotating platform implant for total knee arthroplasty

BACKGROUND: Uncemented total knee arthroplasty is increasing as a potential solution for aseptic loosening via biologic fixation and to increase operative efficiency. However, postoperative radiolucent lines (RLLs) remain a concern for some clinicians. We report on a multicenter analysis of these RLLs over a 2-year period to identify their incidence, progression, and clinical significance. MATERIAL AND METHODS: Institutional review board approval was obtained for this retrospective, multicenter case series. A total of 312 patients treated with a single cruciate-retaining, fully porous coated femoral and tibial component design were included in the study. All patients were evaluated clinically and radiographically in the early postoperative period and at final follow-up (average 2.0 years). Average age of the study group was 58.2 years, and average body mass index was 30.7. Of the total, 66% were male, and 34% were female. Two independent surgeons evaluated the radiographs at the initial postoperative visit and at the most recent follow-up for RLLs. Knee Society Scores and range of motion (ROM) were collected at each visit. RESULTS: We identified RLLs in 25% of patients. All RLLs were less than 1 mm in size and located at the periphery of the tibial implant. None of the RLLs were progressive. At the final follow-up, compared with early postoperative imaging, no new RLLs were identified. Average ROM in flexion was 124 degrees, and the average Knee Society Scores at the most recent clinical follow-up was 96. CONCLUSION: RLLs are commonly seen following cementless TKA, most commonly underneath the tibial tray. Based on this data set, there does not appear to be progression of these RLLs with time, and they do not appear to have an effect on ROM or clinical outcome at 2 years

Investigation of Anti-Relaxation Coatings for Alkali-Metal Vapor Cells Using Surface Science Techniques

Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of anti-relaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10,000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings, in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge X-ray absorption fine structure spectroscopy, and X-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C=C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin anti-relaxation coatings, as well as the design and synthesis of new classes of coating materials.Comment: 12 pages, 12 figures. Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in the Journal of Chemical Physics and may be found at http://link.aip.org/link/?JCP/133/14470

Fluorescence yield near edge spectroscopy of [pi]-bonded CO on Fe(100)

Near edge X-ray absorption fine structure (NEXAFS) spectra of CO adsorbed on the Fe(100) surface are reported. Spectra, obtained by fluorescence yield (FYNES), are presented for each of the four individual CO adsorption configurations observed on this surface. The [pi]-bonded state exhibits an unusual FYNES spectrum and polarization dependence which indicates that the molecule is either extensively rehybridized or tilted with respect to the surface normal. The FYNES spectra of each of the adsorption states directly reflect the perturbation of the carbon-oxygen bond by the surface and track systematically with the heat of adsorption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27641/1/0000017.pd

International approaches to Islamic studies in higher education

This report considers the academic approach of selected countries (including the UK) to the study of Islamic studies in higher education. The objectives of the desk-based research, commissioned by HEFCE, were to: *map different approaches to Islamic studies *understand how publicly funded universities and colleges relate to private institutions that offer programmes of study in or related to Islamic studies *understand the size and scope of Islamic studies capacity in each country in order to reach a judgement about the 'health of the discipline' in each country *identify, for each country, whether Islamic studies has gained in prominence in the past 10 years, for what reason(s) and how policy-makers, Government or funding bodies have responded. The report found that Islamic studies has increased in prominence in the eight countries surveyed. This has led to: *efforts to incorporate aspects of the training of local Muslim leaders, including imams, into higher education programmes *the development of inter- and trans-regional centres for the study of Islam and Muslims *the development of modules related to Islamic studies that can be integrated into wider, and unrelated, programmes of study. These findings will help HEFCE in the shaping of possible options for support for Islamic Studies in the UK

Does Gender Affect Investors' Appetite for Risk? Evidence from Peer-to-Peer Lending

This study investigates the role of gender in financial risk-taking. Specifically, I ask whether female investors tend to fund less risky investment projects than males. To answer this question, I use real-life investment data collected at the largest German market for peer-to-peer lending. Investors' utility is assumed to be a function of the projects expected return and its standard deviation, whereas standard deviation serves as a measure of risk. Gender differences regarding the responses to projects' risk are tested by estimating a random parameter regression model that allows for variation of risk preferences across investors. Estimation results provide no evidence of gender differences in investors' risk propensity: On average, male and female investors respond similarly to the changes in the standard deviation of expected return. Moreover, no differences between male and female investors are found with respect to other characteristics of projects that may serve as a proxy for projects' risk. Significant gender differences in investors' tastes are found only with respect to preferred investment duration, purpose of investment project and borrowers' age