An efficient method for LEED crystallography

Determination of periodic surface structures from analysis of LEED intensity data is usually based on the evaluation of continuous I/V-spectra for a large number of model structures for which all the structural parameters have to be refined simultaneously until the best agreement with the experimental data, as quantified by the minimum of R-factor, is achieved. It is demonstrated that analysis based on intensity data taken only at discrete energy intervals (of up to about 20 eV) leads to no loss in accuracy if compared with the evaluation of continuous I/V-spectra. The introduction of a novel RDE-factor permits in addition to replace the “grid search” technique by a “least-squares” optimisation scheme which enables automatic search of the R-factor minimum at considerably reduced computational efforts. The strength of this technique becomes particularly evident with more complex structures as is demonstrated for Ni(110)-(2 × 1)O and other systems

A LEED structural analysis of the Co(100) surface

The structure of the clean Co(1010) surface has been analysed by LEED. Application of a recently developed computational scheme reveals the prevalence of the termination A in which the two topmost layers exhibit a narrow spacing of 0.62 Å, corresponding to a 12.8(±0.5)% contraction with respect to the bulk value, while the spacing between the second and third layer is slightly expanded by 0.8(±0.2)%

A novel procedure for fast surface structural analysis based on LEED intensity data

By evaluating LEED intensities from different diffraction beams taken only at discrete energy intervals (which may be as large as 15–20 eV) the same degree of reliability in surface structure determination can be reached as with the conventional techniques based on analysis of continuous I/V-spectra. The minimum of the corresponding R-factor can be found by a least-squares fit method, as will be exemplified with a system in which 8 structural parameters were subject to simultaneous refinement

Reconstruction and subsurface lattice distortions in the (2 × 1)O-Ni(110) structure: A LEED analysis

LEED analysis of the reconstructed (2 × 1)O-Ni(110) system clearly favors the “missing row” structure over the “saw-tooth” and “buckled row” models. By using a novel computational procedure 8 structural parameters could be refined simultaneously, leading to excellent R-factors (RZJ = 0.09, RP = 0.18). The adsorbed O atoms are located 0.2 Å above the long bridge sites in [001] direction, presumably with a slight displacement ( 0.1 Å) in [1 0] direction to an asymmetric adsorption site. The nearest-neighbor Ni---O bond lengths (1.77 Å) are rather short. The separation between the topmost two Ni layers is expanded to 1.30 Å (bulk value 1.25 Å), while that between the second and third layer is slightly contracted to 1.23 Å. The third layer is, in addition, slightly buckled (±0.05 Å). The results are discussed on the basis of our present general knowledge about the structure of adsorbate covered metallic surfaces

Standardizing STI Screening in Child Sexual Abuse Cases at the CARES Institute

Children who are sexually abused have a higher risk of contracting STIs and/or becoming pregnant. CDC STI testing guidelines should be adhered to in order to provide the safest outcomes for patients. Physician compliance with testing guidelines plays a significant role in ensuring patient safety, which highlights the importance of ensuring high physician compliance. Identifying ways physicians can improve compliance can enhance patient care. In order to determine compliance rates of the CARES Institute physicians, data was extracted from 275 patient charts from 2017 and 100 patients charts from 2021, before and after a continuing medical education (CME) training was provided to CARES physicians. Statistical analyses were performed on these sets of data to determine compliance rates. A second CME training including conclusions from these analyses was provided to CARES physicians in 2023. Data collection and analysis from new 2023 patient statuses is currently in progress. Results from analysis of the 2017 and 2021 data showed an increase in compliance rates from 2017 to 2021. This highlights the potential benefit of physician education to increasing physician adherence to STI testing protocol. Further physician education is still necessary to reach higher rates of compliance. Future studies can focus on identifying commonly non-documented risk factors for STIs and determining ways to improve documentation

A Lightweight Loudspeaker for Aircraft Communications and Active Noise Control

A series of new, lightweight loudspeakers for use on commercial aircraft has been developed. The loudspeakers use NdFeB magnets and aluminum alloy frames to reduce the weight. The NdFeB magnet is virtually encapsulated by steel in the new speaker designs. Active noise reduction using internal loudspeakers was demonstrated to be effective in 1983. A weight, space, and cost efficient method for creating the active sound attenuating fields is to use the existing cabin loudspeakers for both communication and sound attenuation. This will require some additional loudspeaker design considerations

Coverage-dependent adsorption sites in the K/Ru(0001) system: a low-energy electron-diffraction analysis

The two ordered phases p(2 × 2) at a coverage θ = 0.25 and (√3 × √3)R30° at θ = 0.33 of potassium adsorbed on Ru(0001) were analyzed by use of low-energy electron-diffraction (LEED). In the (√3 × √3)R30° phase, the K atoms occupy threefold hcp sites, while in the p(2 × 2) phase the fcc site is favoured. In both phases, the K hard-sphere radii are nearly the same and close to the covalent Pauling radius

Cholesteryl ester transfer protein (CETP) I405V polymorphism and cardiovascular disease in eastern European Caucasians – a cross-sectional study

Methods A cross-sectional study was conducted to genotype 1028 healthy blood donors and 1517 clinically well characterized elderly for CETP I405V. Results We could not find any association of this polymorphism with age for both, males or females, in any of these cohorts (P = 0.71 and P = 0.57, respectively, for males and P = 0.55 and P = 0.88, respectively, for females). In addition, no association with cardiovascular diseases could be observed in the elderly cohort (males OR = 1.12 and females OR = 0.88). In the same cohort, the CETP V405V genotype was associated with significantly enhanced HDL levels (P = 0.03), mostly owing to the female sex (P = 0.46 for males, P = 0.02 for females), whereas LDL and triglyceride levels were unchanged (P = 0.62 and P = 0.18, respectively). Conclusion Our data support the recent hypothesis that variations enhancing HDL levels without affecting LDL levels are not associated with the risk for cardiovascular diseases