Polymorphism of the glass former ethanol confined in mesoporous silicon

X-ray diffraction patterns of ethanol confined in parallel-aligned channels of approx. 10 nm diameter and 50 micrometer length in mesoporous silicon have been recorded as a function of filling fraction, temperature and for varying cooling and heating rates. A sorption isotherm, recorded in the liquid state, indicates a three monolayer thick, strongly adsorbed wall layer and a capillary condensed fraction of molecules in the pore center. Though the strongly adsorbed film remains in an amorphous state for the entire temperature range investigated, the capillary condensed molecules reproduce the polymorphism of bulk solid ethanol, that is the formation of either crystalline or glass-like states as a function of cooling rate. The critical rate necessary to achieve a vitrification in the mesopores is, however, at least two orders of magnitude smaller than in the bulk state. This finding can be traced both to pure geometrical constraints and quenched disorder effects, characteristic of confinement in mesoporous silicon.Comment: 6 pages, 4 figure

Crystallization of medium length 1-alcohols in mesoporous silicon: An X-ray diffraction study

The linear 1-alcohols n-C16H33OH, n-C17H35OH, n-C19H37OH have been imbibed and solidified in lined up, tubular mesopores of silicon with 10 nm and 15 nm mean diameters, respectively. X-ray diffraction measurements reveal a set of six discrete orientation states (''domains'') characterized by a perpendicular alignment of the molecules with respect to the long axis of the pores and by a four-fold symmetry about this direction, which coincides with the crystalline symmetry of the Si host. A Bragg peak series characteristic of the formation of bilayers indicates a lamellar structure of the spatially confined alcohol crystals in 15 nm pores. By contrast, no layering reflections could be detected for 10 nm pores. The growth mechanism responsible for the peculiar orientation states is attributed to a nano-scale version of the Bridgman technique of single-crystal growth, where the dominant growth direction is aligned parallelly to the long pore axes. Our observations are analogous to the growth phenomenology encountered for medium length n-alkanes confined in mesoporous silicon (Phys. Rev. E 75, 021607 (2007)) and may further elucidate why porous silicon matrices act as an effective nucleation-inducing material for protein solution crystallization.Comment: 4 pages, 4 figures, to appear as a Brief Report in Physical Review

The assessment of the implementation of fuel related legislations and their impact on air quality and public health

The main focus of Work Package 6 of the Aphekom project was: to develop innovative methods to analyse the decrease in air pollution levels following implementation of an European regulation to reduce the sulphur content in liquid fuels; to follow the evolution of health risks over time; to track related effect modifiers; and to quantify the monetary costs of health impacts of the implemented regulation

Profiling SO2 air pollution patterns in 9 EU Aphekom cities: The Aphekom Project

A detailed analysis of hourly pollutant concentrations mainly focusing on SO2 data obtained from 9 centres involved in the Aphekom project was conducted. This involved the generation of individual diurnal SO2 profiles in order to: (i) identify city specific patterns including source apportionment and quantification, (ii) track changes over time, (iii) analyse the changes in SO2 concentrations from different emission sources, i.e. traffic, heating, shipping and industrial sources, overtime

Mortality impacts of sulphur concetrations in 20 European cities in the APHEKOM Project

The implementation of three EU directives to reduce sulphur content in fuel was assessed for mortality impacts in 20 European cities, between 1990 and 2007 in the APHEKOM project. This specific study aimed to examine whether different lag structures apply to the relationships between cardiovascular and respiratory events and SO2 concentrations, which will therefore result in differences in mortality impacts from regulation implementation. Prior evidence has shown that cardiovascular mortality is more likely to be affected by SO2 concentrations on the same or the previous day of the event, while respiratory mortality more likely to show a delayed effect of exposure to the same pollutant

Investigation of a direction sensitive sapphire detector stack at the 5 GeV electron beam at DESY-II

Extremely radiation hard sensors are needed in particle physics experiments to instrument the region near the beam pipe. Examples are beam halo and beam loss monitors at the Large Hadron Collider, FLASH or XFEL. Currently artificial diamond sensors are widely used. In this paper single crystal sapphire sensors are considered as a promising alternative. Industrially grown sapphire wafers are available in large sizes, are of low cost and, like diamond sensors, can be operated without cooling. Here we present results of an irradiation study done with sapphire sensors in a high intensity low energy electron beam. Then, a multichannel direction-sensitive sapphire detector stack is described. It comprises 8 sapphire plates of 1 cm^2 size and 525 micro m thickness, metallized on both sides, and apposed to form a stack. Each second metal layer is supplied with a bias voltage, and the layers in between are connected to charge-sensitive preamplifiers. The performance of the detector was studied in a 5 GeV electron beam. The charge collection efficiency measured as a function of the bias voltage rises with the voltage, reaching about 10 % at 950 V. The signal size obtained from electrons crossing the stack at this voltage is about 22000 e, where e is the unit charge. The signal size is measured as a function of the hit position, showing variations of up to 20 % in the direction perpendicular to the beam and to the electric field. The measurement of the signal size as a function of the coordinate parallel to the electric field confirms the prediction that mainly electrons contribute to the signal. Also evidence for the presence of a polarisation field was observed.Comment: 13 pages, 7 figures, 3 table

The APHEKOM Project: A literature review of air pollution interventions and their impact of public health

Intervention studies play an important role in supporting and complementing scientific validation of results of epidemiological non-intervention studies linking air pollution and health. In this paper a collection of existing published intervention studies is reviewed with the aim to give a summarized overview spanning a variety of approaches regarding the type of the intervention and findings with the main focus on studies that assessed interventions that improved air quality and the associated positive impact on public health. Air pollution interventions were defined as events aimed at reducing air pollution and also events where air pollution reductions occurred as a side effect

Genetic diversity and low stratification of the population of the United Arab Emirates

© Copyright © 2020 Tay, Henschel, Daw Elbait and Al Safar. With high consanguinity rates on the Arabian Peninsula, it would not have been unexpected if the population of the United Arab Emirates (UAE) was shown to be relatively homogenous. However, this study of 1000 UAE nationals provided a contrasting perspective, one of a relatively heterogeneous population. Located at the apex of Europe, Asia, and Africa, the observed diversity could be explained by a plethora of migration patterns since the first Out-of-Africa movement. A strategy to explore the extent of genetic variation of the population of the UAE is presented. The first step involved a comprehensive population stratification study that was instructive for subsequent whole genome sequencing (WGS) of suitable representatives (which is described elsewhere). When these UAE data were compared to previous smaller studies from the region, the findings were consistent with a population that is a diverse and admixed group of people. However, rather than sharp and distinctive clusters, cluster analysis reveals low levels of stratification throughout the population. UAE emirates exhibit high within-Emirate-distance/among-Emirate distance ratios. Supervised admixture analysis showed a continuous gradient of ancestral populations, suggesting that admixture on the south eastern tip of the Arabian Peninsula occurred gradually. When visualized using a unique technique that combined admixture ratios and principal component analysis (PCA), unappreciated diversity was revealed while mitigating projection bias of conventional PCA. We observe low population stratification in the UAE in terms of homozygosity versus separation cluster coefficients. This holds for the UAE in a global context as well as for isolated cluster analysis of the Emirati birthplaces. However, the subtle clustering observed in the Emirates reflects geographic proximity and historic migration events. The analytical strategy used here highlights the complementary nature of data from genotype array and WGS for anthropological studies. Specifically, genotype array data were instructive to select representative subjects for WGS. Furthermore, from the 2.3 million allele frequencies obtained from genotype arrays, we identified 46,481 loci with allele frequencies that were significantly different with respect to other world populations. This comparison of allele frequencies facilitates variant prioritization in common diseases. In addition, these loci bear great potential as biomarkers in anthropological and forensic studies