Transverse distribution of the transport current density in (Bi, Pb)2223 tapes

The distribution of the critical transport current density, Jc, has been measured across the core thickness of silver sheathed (Bi, Pb)2223 tapes which contained silver addition of different particle sizes. We have found the Jc of tapes without silver addition and with 8 wt% silver addition of small particle size decreases continuously with distance from the core-sheath interface. The Jc of layers close to the silver sheath is up to four times higher than that of central layers, e.g. 3 × 104A cm?2 near the sheath and 7 × 103 Acm?2 in the centre at 77 K and self field. The tape with addition of 50 wt% 80 ?m silver particles shows a uniform Jc of about 2 × 104 A cm?2 throughout the core thickness. The V?I characteristics of the baser core of the tape without silver addition have also been measured in magnetic fields

Socio-Demographic Characteristics and Patterns of Substance Use Disorder in Oman : A retrospective study of the National Surveillance Programme between 2004 and 2018

Objectives: Substance use disorder is a global challenge. Therefore, this study aimed to provide an updated view of socio-demographic characteristics and patterns of substance use in Oman. Methods: This retrospective descriptive study was conducted between 2004 and 2018. Data were retrieved from Oman’s National Drug Addict Registry. The data collected included the socio-demographic characteristics of registered cases, the proportion of various psychoactive substances’ consumption and their routes of administration, the associated sociodemographic determinants as well as comorbid conditions. Results: A total of 6,453 cases were registered during the study’s timeframe. The majority of which were Omani (97.9%), male (98.7%), single (57.9%), unemployed (50.2%), had an education level below university (81.0%) and were adolescents and young adults (77.0%). Opiates were the most common substance used (66.6%) and more than half of the sample were polydrug users (51.0%). Injecting-drug users constituted 53.4% of the total registered cases. The proportion of people with hepatitis virus C, hepatits virus B and HIV among the registered cases were 46.9%, 5.1% and 3.7%, respectively. Conclusion: The findings are in favour of rapidly escalating the introduction of a substance use preventive programme at all school levels as well as making opioid substitution therapy and other harm reduction programmes available in Oman. Keywords: Substance Use Disorders; Intravenous Drug Abuse; Opioid-Related Disorders; Comorbidity; Oman

The characterisation of dental enamel using transmission Kikuchi diffraction in the scanning electron microscope combined with dynamic template matching

The remarkable physical properties of dental enamel can be largely attributed to the structure of the hydroxyapatite (HAp) crystallites on the sub-micrometre scale. Characterising the HAp microstructure is challenging, due to the nanoscale of individual crystallites and practical challenges associated with HAp examination using electron microscopy techniques. Conventional methods for enamel characterisation include imaging using transmission electron microscopy (TEM) or specialised beamline techniques, such as polarisation-dependent imaging contrast (PIC). These provide useful information at the necessary spatial resolution but are not able to measure the full crystallographic orientation of the HAp crystallites. Here we demonstrate the effectiveness of enamel analyses using transmission Kikuchi diffraction (TKD) in the scanning electron microscope, coupled with newly-developed pattern matching methods. The pattern matching approach, using dynamic template matching coupled with subsequent orientation refinement, enables robust indexing of even poor-quality TKD patterns, resulting in significantly improved data quality compared to conventional diffraction pattern indexing methods. The potential of this method for the analysis of nanocrystalline enamel structures is demonstrated by the characterisation of a human enamel TEM sample and the subsequent comparison of the results to high resolution TEM imaging. The TKD – pattern matching approach measures the full HAp crystallographic orientation enabling a quantitative measurement of not just the c-axis orientations, but also the extent of any rotation of the crystal lattice about the c-axis, between and within grains. Results presented here show how this additional information highlights potentially significant aspects of the HAp crystallite structure, including intra-crystallite distortion and the presence of multiple high angle boundaries between adjacent crystallites with rotations about the c-axis. These and other observations enable a more rigorous understanding of the relationship between HAp structures and the physical properties of dental enamel

The Origin and MgCl2–NaCl Variations in an Athalassic Sag Pond: Insights from Chemical and Isotopic Data

The examination of past and new chemical–isotopic data (2H/1H–18O/16O,11B/10B and87Sr/86Sr ratios) shows the meteoric origin of the Sawa Lake (Muthanna Governorate, Iraq) and its connection with the local aquifers, which feed the lake via the groundwater emerging from its floor through fault systems. The chemical and isotopic evaporation models are traced by geochemical computer codes by using a different composition of some potential inflows to the lake (e.g., the Euphrates River and Dammam aquifer). The main product of the chemical evaporation models is gypsum, as confirmed by the mineralogical examination of the sediment and the surrounding outcrops. A strong18O–2H enrichment is a consequence of the evaporation effect in arid regions; δ18O–Cl models and δ11B = + 23.4‰ exclude the contribution of any seawater-derived fluids. This latter value along with87Sr/86Sr = 0.707989 suggests a mixed origin from the Eocene–Miocene aquifers. The isotope and chemical evaporation paths from the meteorically recharged sources match the lake composition. However, compositional switches from NaCl toward MgCl2occurred in the last decade and are related to post-drought periods, showing that the interaction of the recharging waters with the local soils (Na–Mg exchange and/or the leaching of the top layer salts) have a role in the chemical composition. This demonstrates that the lake is significantly influenced by climatic variations