Mechanical, tribological, and stress analyses of ion-beam-deposited boron-rich boron nitride films with increasing N content

Author name used in this publication: C. L. ChoyVersion of RecordPublishe

X-ray photoemission spectroscopy of nonmetallic materials : electronic structures of boron and BᵪOᵧ

Author name used in this publication: H. Huang2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Age, period, and cohort analysis of regular dental care behavior and edentulism: A marginal approach

<p>Abstract</p> <p>Background</p> <p>To analyze the regular dental care behavior and prevalence of edentulism in adult Danes, reported in sequential cross-sectional oral health surveys by the application of a marginal approach to consider the possible clustering effect of birth cohorts.</p> <p>Methods</p> <p>Data from four sequential cross-sectional surveys of non-institutionalized Danes conducted from 1975-2005 comprising 4330 respondents aged 15+ years in 9 birth cohorts were analyzed. The key study variables were seeking dental care on an annual basis (ADC) and edentulism. For the analysis of ADC, survey year, age, gender, socio-economic status (SES) group, denture-wearing, and school dental care (SDC) during childhood were considered. For the analysis of edentulism, only respondents aged 35+ years were included. Survey year, age, gender, SES group, ADC, and SDC during childhood were considered as the independent factors. To take into account the clustering effect of birth cohorts, marginal logistic regressions with an independent correlation structure in generalized estimating equations (GEE) were carried out, with PROC GENMOD in SAS software.</p> <p>Results</p> <p>The overall proportion of people seeking ADC increased from 58.8% in 1975 to 86.7% in 2005, while for respondents aged 35 years or older, the overall prevalence of edentulism (35+ years) decreased from 36.4% in 1975 to 5.0% in 2005. Females, respondents in the higher SES group, in more recent survey years, with no denture, and receiving SDC in all grades during childhood were associated with higher probability of seeking ADC regularly (<it>P </it>< 0.05). The interaction of SDC and age (<it>P </it>< 0.0001) was significant. The probabilities of seeking ADC were even higher among subjects with SDC in all grades and aged 45 years or older. Females, older age group, respondents in earlier survey years, not seeking ADC, lower SES group, and not receiving SDC in all grades were associated with higher probability of being edentulous (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>With the use of GEE, the potential clustering effect of birth cohorts in sequential cross-sectional oral health survey data could be appropriately considered. The success of Danish dental health policy was demonstrated by a continued increase of regular dental visiting habits and tooth retention in adults because school dental care was provided to Danes in their childhood.</p

Depletion of surface boron of heavily boron-doped diamond films by annealing

Surface boron of heavily boron-doped polycrystalline diamond thin films was found to be depleted upon annealing. Based on analyses using X-ray photoelectron spectroscopy, X-ray photoelectron energy loss spectroscopy, time-of-flight secondary ion mass spectroscopy and Auger electron spectroscopy, surface boron was found to be removed when the diamond film was annealed at 500 °C in vacuum and continued to be eliminated at 900 °C. The loss of surface boron undoubtedly altered the electronic properties of the diamond surface. This phenomenon is important in the fabrication of diamond-based electronic devices

Effects of ion beam bombardment on electrochromic tungsten oxide films studied by X-ray photoelectron spectroscopy and Rutherford back-scattering

The effect of ion bombardment on thermally evaporated and magnetron sputtered tungsten oxide films were investigated using X-ray photoelectron spectroscopy (XPS). Results show that irrespective of the porosity and crystallinity of the film samples formed with different techniques and conditions, ion bombardment induced preferential sputtering of oxygen, resulting in a decrease of oxygen/tungsten (O/W) ratio with increasing sputtering time. Samples experienced electrochromic switching cycles also show the same effect, except that a higher O/W ratio is detected because the tungsten oxide film reacts with the LiClO4-propylene carbonate electrolyte. Angle-resolved XPS experiments further confirm preferential sputtering of oxygen, suggesting that ion beam sputtering used in XPS for pre-cleaning and depth profile analysis of tungsten oxide must be used with caution. Rutherford back-scattering gives more reliable composition data of tungsten oxide, since it does not involve any sputtering process

Magnetic properties and structure evolution of amorphous Co-C nanocomposite films prepared by pulsed filtered vacuum arc deposition

The magnetic properties and structure evolution of CoxC1-x (x=44, 65, 71 at. \%) nanocomposite films prepared by pulsed filtered vacuum arc deposition were studied. The as-deposited films consist of amorphous Co clusters in a-C and are soft ferromagnets. The low coercivity in the amorphous films is due to the very low anisotropy of the amorphous Co clusters. After annealing in vacuum at 350 degrees C for 1 h, the Co clusters crystallize and these films become magnetically harder. The magnetic hardening is attributed to the enhanced magnetic anisotropy of the nanocrystals. Their saturation magnetization reduces slightly. This is attributed to the reduction of the density of states at the Fermi level caused by the crystallization of the amorphous Co clusters. (C) 2000 American Institute of Physics. [S0021-8979(00)03021-8]

SIMS analysis of lead isotope composition in ancient Chinese metallic artefacts

An attempt on the use of secondary ion mass spectroscopy (SIMS) in studying ancient Chinese bronze is reported with an evaluation of the suitability of SIMS for the provenance study of ancient bronze objects. The advantage of using SIMS in the study of the lead isotope ratio is the high sensitivity that enables the examination of small fragments of valuable relies that are often difficult to collect. The application of SIMS in this direction widens the sampling area, which is limited by the use of thermal ionization mass spectroscopy (TIMS). The focus of the study has been placed on the precision of SIMS when compared to TIMS and the effect of sample matrices on the precision. Samples of Chinese bronze artefacts and a standard lead sample (SRM 981) were tested for their lead isotope ratios using both SIMS and TIMS. A comparison of the data obtained using the two techniques showed that SIMS results have a relatively large standard deviation, which was attributed to the non-uniformity of the ancient samples and the single-isotope detection system of the SIMS set-up used, Matrix effects were found to be small among bronze samples of different compositions. Non-conducting samples can also be analysed when a specimen isolation technique is employed. Although SIMS gave higher uncertainties than TIMS, the SIMS technique can be applied easily to differentiate the high radiogenic lead in Shang bronze artefacts from common lead. Copyright (C) 2000 John Wiley & Sons, Ltd

Prospective randomized study of selective neck dissection versus observation for no neck of early tongue carcinoma

Background. There are controversies on the bene-fits of elective neck dissection (END) for oral tongue carcinoma. Method. This is a prospective randomized study of elective selective I, II, III neck dissection versus observation for N0 neck of stage I to II oral tongue carcinoma. There were 35 patients on the observation arm and 36 patients on the END arm. The main outcome assessment parameters are node-related mortality and disease-specific survival rate. Results. There were 11 patients in the observed arm and 2 patients in the END arm who developed nodal recurrence alone without associated local or distant recurrence. All 13 patients were salvaged, and no patient died of nodal recurrence. The 5-year disease-specific survival rate was 87% for the observation arm and was 89% for the END arm; the 2% difference was not significant. Conclusion. Observation may be an acceptable alternative to END if strict adherence to a cancer surveillance protocol is followed. © 2009 Wiley Periodicals, Inc.link_to_subscribed_fulltex