Observing non-classical crystallisation processes in gypsum via infrared attenuated total reflectance spectroscopy

The nature of crystallisation processes is of major interest, as they are among the most frequently occurring reactions associated with a variety of relevant processes in chemistry, biochemistry, and geochemistry. In this study, an innovative approach towards fundamentally understanding crystallisation pathways in a seemingly simple system-gypsum-has been developed via infrared spectroscopic techniques. Specifically, infrared attenuated total reflection spectroscopy (IR-ATR) was instrumental in revealing detailed information on inter- and intramolecular interactions during gypsum crystallization via subtle changes in the vibrational spectra of the involved reactants. When applying D2O as an isotope marker, it was shown that isotopically labelled water may serve as a viable spectroscopic probe during mid-infrared (3-15 µm) studies providing unique insight into the crystallization process at molecular-level detail. In addition, it was revealed that H2O and D2O give rise to distinctly different reaction kinetics during the crystallization process

Nanometer-scale sharpness in corner-overgrown heterostructures

A corner-overgrown GaAs/AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile of 3.5 nm width. In the AlGaAs layers we observe self-ordered diagonal stripes, precipitating exactly at the corner, which are regions of increased Al content measured by an XEDS analysis. A quantitative model for self-limited growth is adapted to the present case of faceted MBE growth, and the corner sharpness is discussed in relation to quantum confined structures. We note that MBE corner overgrowth maintains nm-sharpness even after microns of growth, allowing the realization of corner-shaped nanostructures.Comment: 4 pages, 3 figure

Surface Rearrangement and Evaporation Kinetics of Supported Gold Nanoparticle Catalysts

Heterogeneous catalysts consisting of supported metallic nanoparticles typically derive exceptional catalytic activity from their large proportion of under-coordinated surface sites which promote adsorption of reactant molecules. Simultaneously, these high energy surface configurations are unstable, leading to nanoparticle growth or degradation, and eventually a loss of catalytic activity. Surface morphology of catalytic nanoparticles is paramount to catalytic activity, selectivity, as well as degradation rates, however, it is well-known that harsh reaction conditions can cause the surface structure to change. Still, limited research has focused on understanding the link between nanoparticle surface facets and degradation rates or mechanisms. Here, we study a model Au supported catalyst system over a range of temperatures using a combination of \textit{in situ} Transmission Electron Microscopy, kinetic Monte Carlo simulations, and density functional theory calculations to establish an atomistic picture of how variations in surface structures and atomic coordination environments lead to shifting evolution mechanisms as a function of temperature. By combining experimental results, which yield direct observation of dynamic shape changes and particle evaporation rates, with computational techniques, which enable understanding the fundamental thermodynamics and kinetics of nanoparticle evolution, we illustrate a two-step evolution mechanism in which mobile adatoms form through desorption from low-coordination facets and subsequently evaporate off the particle surface. By understanding the role of temperature in the competition between surface diffusion and evaporation, we are able to show how individual atomic movements lead to particle-scale morphological changes, and rationalize why evaporation rates vary between particles in a system of nearly identical nanoparticles

Evolution and stabilization of subnanometric metal species in confined space by in situ TEM

Understanding the behavior and dynamic structural transformation of subnanometric metal species under reaction conditions will be helpful for understanding catalytic phenomena and for developing more efficient and stable catalysts based on single atoms and clusters. In this work, the evolution and stabilization of subnanometric Pt species confined in MCM-22 zeolite has been studied by in situ transmission electron microscopy (TEM). By correlating the results from in situ TEM studies and the results obtained in a continuous fix-bed reactor, it has been possible to delimitate the factors that control the dynamic agglomeration and redispersion behavior of metal species under reaction conditions. The dynamic reversible transformation between atomically dispersed Pt species and clusters/nanoparticles during CO oxidation at different temperatures has been elucidated. It has also been confirmed that subnanometric Pt clusters can be stabilized in MCM-22 crystallites during NO reduction with CO and H2

Response of Multi-strip Multi-gap Resistive Plate Chamber

A prototype of Multi-strip Multi-gap Resistive Plate chamber (MMRPC) with active area 40 cm $\times$ 20 cm has been developed at SINP, Kolkata. Detailed response of the developed detector was studied with the pulsed electron beam from ELBE at Helmholtz-Zentrum Dresden-Rossendorf. In this report the response of SINP developed MMRPC with different controlling parameters is described in details. The obtained time resolution ($\sigma_t$) of the detector after slew correction was 91.5$\pm$3 ps. Position resolution measured along ($\sigma_x$) and across ($\sigma_y$) the strip was 2.8$\pm$0.6 cm and 0.58 cm, respectively. The measured absolute efficiency of the detector for minimum ionizing particle like electron was 95.8$\pm$1.3 $\%$. Better timing resolution of the detector can be achieved by restricting the events to a single strip. The response of the detector was mainly in avalanche mode but a few percentage of streamer mode response was also observed. A comparison of the response of these two modes with trigger rate was studiedComment: 19 pages, 26 figure

Perceived Financial Satisfaction, Health Related Quality of Life and depressive Symptoms in Early Pregnancy

Objectives To assess the associations of perceived financial satisfaction and health-related quality of life (HRQoL) and depressive symptoms in an unselected pregnant population in early pregnancy. Methods 750 consecutive pregnant women attending the first communal ultrasound examination before gestational week 14 were invited to participate. Questionnaires assessing HRQoL (15D), depressive symptoms (Edinburgh Depression Scale, EPDS), medical, obstetric, and socioeconomic status were handed out. The participants were divided into three groups according to their satisfaction with their financial status, (unsatisfied, somewhat satisfied, and satisfied). Main outcome measures were 15D and EPDS-scores and dimensions of HRQoL. Results 325 (43,3%) questionnaires were returned. The mean 15D-score for HRQoL was 0,926 (SD 0,056). The financially unsatisfied women had lower HRQoL than women in more satisfied groups (0.906, 0.923 and 0.931, p = 0.012). The result remained significant, even after adjusting for age and education(p = 0.032). The unsatisfied women had a higher mean body mass index (BMI) (25.4, 24.4 and 23.2 kg/m(2), p for linearity = 0.002), were more often smokers, (13 vs. 4 and 3%, p = 0.029), and had experienced at least one abortion (18, 14 and 7%, p = 0.017). Dimensions of depression, distress and sleep explained the differences between the groups. 27% of unsatisfied women scored EPDS ae10 points suggesting increased risk of depression. Conclusions Financial satisfaction in early pregnancy associates with HRQoL and risk of perinatal depressive symptoms. Unsatisfied women more often have risk factors for unfavourable pregnancy outcomes which may influence the later health and wellbeing of the mother and child.Peer reviewe

Physical activity and health-related quality of life among high-risk women for type 2 diabetes in the early years after pregnancy

Background Previous studies have shown that physical activity (PA) correlates positively with health-related quality of life (HRQoL) in the general population. Few studies have investigated associations between device-measured PA and HRQoL among premenopausal women at risk for type 2 diabetes (T2D). In addition to physical well-being, general well-being improved by PA has been suggested to strengthen PA's benefits in reducing metabolic diseases. The aim of this study was to examine the associations between PA and HRQoL (general and dimensions) among high-risk women in the early post-pregnancy years when T2D risk is highest and to estimate whether current obesity or prior gestational diabetes (GDM) modified these associations. Methods This cross-sectional study of high-risk women [body mass index (BMI) >= 30 kg/m(2) and/or prior GDM)]4-6 years after delivery measured sleep, sedentary time, daily steps, and light (LPA), moderate-to-vigorous (MVPA), and vigorous PA (VPA) with the SenseWear ArmbandTM accelerometer for seven days and HRQoL with the 15D instrument. Results The analyses included 204 women with a median (IQR) age of 39 (6.0) years and a median BMI of 31.1 kg/m(2) (10.9). 54% were currently obese (BMI >= 30 kg/m(2)), and 70% had prior gestational diabetes (GDM+). Women with obesity had lower PA levels than women with normal weight or overweight (p = 30 kg/m(2)), the associations remained significant only in women without obesity. Among them, sleep, total steps, MVPA, and VPA were positively associated with 15D. Conclusions Higher PA levels are associated with better HRQoL among high-risk women with normal weight and overweight but no differences were found among women affected by obesity in the early years after pregnancy. Trial registration Ethics committees of Helsinki University Hospital (Dnro 300/e9/06) and South Karelian Central Hospital (Dnro 06/08).Peer reviewe

Correlation of pre-operative cancer imaging techniques with post-operative gross and microscopic pathology images

In this paper, different algorithms for volume reconstruction from tomographic cross-sectional pathology slices are described and tested. A tissue-mimicking phantom made with a mixture of agar and aluminium oxide was sliced at different thickness as per pathological standard guidelines. Phantom model was also virtually sliced and reconstructed in software. Results showed that shape-based spline interpolation method was the most precise, but generated a volume underestimation of 0.5%