Reflectivity and scattering measurements of an Advanced X-ray Astrophysics Facility test coating sample

Reflectivity and scattering profile measurements were made on a gold-coated witness sample produced to evaluate mirror coatings for the Advanced X-ray Astrophysics Facility program. Reflectivity measurements were made at Al K, Ti K, and Cu K energies as a function of incident graze angle. The results are fit to a model that includes the effects of roughness, particulate and organic contamination layers, and gold-coating density. Reflectivities are close to theoretical, with the difference being well accounted for by 4.1 ? of roughness at spatial frequencies above 4 μm(-1), a gold-coating density equal to 0.98 bulk, and a surface contaminant layer 27 ? thick. Scattering measurements extending to ±35 arcmin of the line center were obtained by the use of Al K x rays and incidence angles from 0.75° to 3°. The scattering profiles imply a power spectral density of surface-scattering frequencies that follows a power law with an index of -1.0 and a total surface roughness for the spatial frequency band between 0.05 μm(-1) and 4 μm(-1) of 3.3 ? Combining the roughnesses derived from both the reflectivity and scattering measurements yields a total roughness of 5.3 ? for scattering frequencies between 0.05 μm(-1) and 15,000 μm(-1).     

Characterisation of a uranium ore using multiple X-ray diffraction based methods

Uranium bearing ores are often a complex mixture of minerals and compounds, a number of which are not of economic importance and are commonly referred to as gangue materials. In order to improve the efficiency of the dissolution stage of the overall uranium extraction process, a greater understanding of the minerals and compounds present in the ore is required. A greater knowledge of the gangue materials present is important as they can influence various aspects of the dissolution process such as providing potential adsorption sites for aqueous uranium species and through influencing the equilibrium of reactions involving aqueous uranium species. In this study the mineralogy of a uranium ore was investigated using a range of X-ray diffraction (XRD) based methods including in situ high temperature XRD and XRD using a synchrotron beam line. The results obtained from standard XRD (Cu Kα), high temperature XRD and synchrotron XRD (16.534 keV) were compared and a number of minerals were identified. The improved spatial resolution and intensity of the synchrotron data allowed for superior phase identification of a variety of minerals where standard X-ray techniques gave inconclusive results.     

Evaluation of Instructional Design of Computer‐Based Teaching Modules for a Manufacturing Processes Laboratory

Studies concerning student preferences and student learning as a function of the instructional design and delivery of a computer‐based teaching (CBT) module are presented. The studies were conducted in conjunction with the development of twenty‐one CBT modules for an Introduction to Manufacturing Processes laboratory that emphasized metal removal. Study results indicate there is no statistically relevant difference in learning between students using material presented with traditional multimedia (35 mm slides and cassette tapes) and the identical material presented with digital multimedia. Engineering students' preferences for interface design and audio‐visual information presentation are also presented. The most important result is that learning outcomes of a reader‐driven CBT module were found to be statistically lower than those associated with author‐driven CBT module, especially for average and below‐average students. These results suggest that if students must absolutely understand material, e.g., laboratory safety, the CBT should be author‐driven. Based on these results, we speculate that average and below average engineering students are more linear learners. A hybrid scheme, where information presentation transitions from an author‐driven to a reader‐driven environment may help weaker students develop better non‐linear, open‐ended problem solving skills.     

Preliminary study of the effect of aging following irradiation on the wear of ultrahigh-molecular-weight polyethylene

Several studies have indicated that degradation of ultrahigh-molecular-weight polyethylene following gamma irradiation in air adversely affects the mechanical properties of the material; however, it is not known how this subsequently affects its wear rate. Wear studies have therefore been performed on three groups of ultrahigh-molecular-weight polyethylene; unirradiated material, recently irradiated material (aged for 2 months), and aged irradiated material (aged for 5 years). The aging took place in sterile packaging on the shelf. The wear studies were carried out on a tri-pin-on-disk wear tester, with a pin from each type of material being studied in each test. In each test the wear rate of the nonirradiated material was slightly lower than the 2-month-aged, irradiated material. The 5-year-aged, irradiated material had the highest wear rate, and this was significantly greater than that of the unirradiated material (P < .05).     

Precision X-ray spectroscopy on 8.5 MeVamu heavy ions

A new experimental capability has been developed at the Lawrence Berkeley Laboratory Super-HILAC to investigate questions relating to high resolution atomic spectroscopy. A key element of these measurements is a dual arm Johann spectrometer. The ion beam passes inside the Rowland circle of two curved crystals which are mounted such that diffracted X-rays have equal and opposite linear Doppler shifts. The X-ray lines are detected with high speed X-ray film mounted on the Rowland circle. The beam-crystal geometry is arranged so a spectral range θ_B ~ 30°–70° is detected. The spectrometer efficiency is high with useful exposures obtained with only 10 mC of beam. A wavelength calibration is obtained by simultaneously exposing the film with diffracted K and L X-rays from an X-ray tube. X-ray lines from the beam are slanted, with respect to the calibration lines, due to Doppler shifts arising from X-rays incident on the crystal at angles other than perpendicular to the diffraction plane. The slope of these lines provides an independent determination of the beam velocity, which is used to correct for the transverse Doppler shift. Typical results are presented.     

The effectiveness of bone density measurement and associated treatments for prevention of fractures. An international collaborative review

This review assesses the evidence regarding the effectiveness of bone density measurement (BDM) screening and related interventions--hormone replacement therapy (HRT) and intranasal salmon calcitonin (SCT[N])--in menopausal women to prevent fractures in later life. Data sources included systematic reviews of evidence and relevant primary studies identified through literature searches on MEDLINE and EMBASE. Study selection included trials of BDM screening programs, prospective studies examining the predictive value of BDM, randomized controlled trials, cohort studies, and case-control studies of HRT and SCT (N). The evidence was evaluated using a classification system incorporating study design and quality. Outcomes were measured in terms of relative risk of fracture for a 1 SD decrease in bone mineral density below the age-adjusted mean, relative risks or odds ratios for fractures associated with treatments, and proportion of hip fractures potentially prevented by BDM screening linked to treatments. Fair evidence from prospective cohort studies suggests that BDM can predict the risk of fractures, but not with high accuracy. Fair evidence from low-quality randomized controlled trials and observational studies suggests that HRT and SCT(N) are efficacious in preventing fractures. Good evidence supports the efficacy of these treatments in preserving bone mass, but there is fair evidence that the effect wears off after cessation of therapy. There is little evidence on the impact of screening menopausal women with BDM in association with HRT or SCT(N) treatment. Estimates based on combining existing evidence regarding the predictive value of BDM and efficacy of HRT suggests that 1-7% of hip fractures might be prevented.     

On-line monitoring of powder blend homogeneity by near-infrared spectroscopy

Near-infrared spectroscopy is evaluated as an on-line technique for monitoring the homogeneity of a pharmaceutical blend during the blending process. Blends containing 10% sodium benzoate (model active), which provided an aromatic functionality typical of many pharmaceutical compounds, 39% microcrystalline cellulose (Avicel PH102), 50% lactose, and 1% magnesium stearate were developed to mimic the properties of an actual pharmaceutical blend. A twin-shell V-blender was modified to allow installation of a diffuse reflectance fiber-optic probe at the axis of rotation, and spectra were collected during three experiments using a commercially available near-infrared spectrophotometer. In each experiment, blender control and spectral data collection were controlled by a compilation of software packages. The experiments detected spectral changes which eventually converged to a point of constant variance. Further analysis of the spectral data showed the blend is homogeneous long before a typical blending period is complete. Near-infrared spectroscopy has proven to be a feasible and effective method for the "real time" noninvasive determination of homogeneity in a pharmaceutical blend.     

MRZ code extraction from visa and passport documents using convolutional neural networks

International Journal on Document Analysis and Recognition (IJDAR) - Detecting and extracting information from the machine-readable zone (MRZ) on passports and visas is becoming increasingly...