Reproducibly emitting reference materials for volatile and semi-volatile organic compounds—using finite element modeling for emission predictions

Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. A VOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE?) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.     

Primary acute angle closure: long-term clinical outcomes over a 10-year period in the Chinese population

To investigate long-term clinical outcomes after acute angle closure in the Chinese population. A 10-year retrospective review of primary acute angle closure in Hong Kong Chinese to document patient demographics, treatment, and pre- and post-acute angle closure intraocular pressure (IOP) and visual acuity (VA). The year of attack was correlated with the timing of laser, last VA and IOP, and the number of anti-glaucoma eye drops. In 210 eyes (200 patients), 10 % had a simultaneous bilateral acute angle closure. VA improvement was noted in 68.6 % of eyes whilst 11.4 % were blinded. At 3.7 ± 2.4 years of follow-up, 49.5 % had IOP <21 mmHg with medication or surgery, 41.9 % needed anti-glaucoma eye drops, and 13.8 % had undergone trabeculectomy. The older the year of attack, the poorer the VA (r = 0.2, p = 0.03) and the longer the laser wait time (r = 0.3, p < 0.0001). VA outcome and laser promptness in acute angle closure has improved over the years. At 4 years after the attack, 50 % had normal IOP, 69 % had improved VA but 11 % were blinded.     

The international migration of dentists: directions for research and policy

In 2010, the World Health Organization Global Code of Practice for International Recruitment of Health Personnel (the WHO Code) was adopted by the 193 Member States of the WHO. The WHO Code is a tool for global diplomacy, providing a policy framework to address the challenges involved in managing dentist migration, as well as improving the retention of dental personnel in source countries. The WHO Code recognizes the importance of migrant dentist data to support migration polices; minimum data on the inflows, outflows and stock of dentists are vital. Data on reasons for dentist migration, job satisfaction, cultural adaptation issues, geographic distribution and practice patterns in the destination country are important for any policy analysis on dentist migration. Key challenges in the implementation of the WHO Code include the necessity to coordinate with multiple stakeholders and the lack of integrated data on dentist migration and the lack of shared understanding of the interrelatedness of workforce migration, needs and planning. The profession of dentistry also requires coordination with a number of private and nongovernmental organizations. Many migrant dentist source countries, in African and the South‐Asian WHO Regions, are in the early stages of building capacity in dentist migration data collection and research systems. Due to these shortcomings, it is prudent that developed countries take the initiative to pursue further research into the migration issue and respond to this global challenge.     

Identification of early vascular calcification with 18F-sodium fluoride: potential clinical application

Vascular calcification plays a prominent role in cardiovascular disease. Once considered to be a passive consequence of aging, this pathological process is now accepted to be dynamic and tightly regulated, its onset triggered by inflammation and necrosis and its progression bearing key similarities to osteogenesis. A major potential advance in our ability to understand the natural history and clinical implications of vascular calcification is the detection of its early and dynamic stages through the use of the positron-emitting radiotracer, ¹⁸F-sodium fluoride. Alongside anatomical information gained from computed tomography, hybrid positron emission and computed tomography (PET/CT) imaging with ¹⁸F-sodium fluoride has, for the first time, enabled the non-invasive detection of microcalcification within the aortic valve, great vessels, and vulnerable coronary plaque. This has raised promise that exploring this process may allow improved risk prediction, better application of current therapies and ultimately the development of novel treatments to target this widespread pathology.     

How superhydrophobicity breaks down

A droplet deposited or impacting on a superhydrophobic surface rolls off easily, leaving the surface dry and clean. This remarkable property is due to a surface structure that favors the entrainment of air cushions beneath the drop, leading to the so-called Cassie state. The Cassie state competes with the Wenzel (impaled) state, in which the liquid fully wets the substrate. To use superhydrophobicity, impalement of the drop into the surface structure needs to be prevented. To understand the underlying processes, we image the impalement dynamics in three dimensions by confocal microscopy. While the drop evaporates from a pillar array, its rim recedes via stepwise depinning from the edge of the pillars. Before depinning, finger-like necks form due to adhesion of the drop at the pillar’s circumference. Once the pressure becomes too high, or the drop too small, the drop slowly impales the texture. The thickness of the air cushion decreases gradually. As soon as the water–air interface touches the substrate, complete wetting proceeds within milliseconds. This visualization of the impalement dynamics will facilitate the development and characterization of superhydrophobic surfaces.     

Microstructural basis of contusion expansion in traumatic brain injury: insights from diffusion tensor imaging

Traumatic brain injury (TBI) is often exacerbated by events that lead to secondary brain injury, and represent potentially modifiable causes of mortality and morbidity. Diffusion tensor imaging was used to characterize tissue at-risk in a group of 35 patients scanned at a median of 50 hours after injury. Injury progression was assessed in a subset of 16 patients with two scans. All contusions within the first few days of injury showed a core of restricted diffusion, surrounded by an area of raised apparent diffusion coefficient (ADC). In addition to these two well-defined regions, a thinner rim of reduced ADC was observed surrounding the region of increased ADC in 91% of patients scanned within the first 3 days after injury. In patients who underwent serial imaging, the rim of ADC hypointensity was subsumed into the high ADC region as the contusion enlarged. Overall contusion enlargement tended to be more frequent with early lesions, but its extent was unrelated to the time of initial imaging, initial contusion size, or the presence of hemostatic abnormalities. This rim of hypointensity may characterize a region of microvascular failure resulting in cytotoxic edema, and may represent a ‘traumatic penumbra'' which may be rescued by effective therapy.     

Keramikimplantate

In den letzten Jahren l?sst sich eine steigende Nachfrage nach keramischem Zahnersatz verzeichnen. Sei es aus Biokompatibilit?tsgründen, aus ganzheitsmedizinischen oder ?sthetischen überlegungen – Keramik wird nicht nur als Restaurationsmaterial immer pr?senter, sondern auch in der zahn?rztlichen Implantologie.