A Study on Correlations Between the Initial Optical and Scintillation Properties and Their Radiation Damage for Lead Tungstate Crystals

This paper presents a study of correlations between the initial optical and scintillation properties and their radiation damage for mass produced lead tungstate crystals. A correlation was observed between crystal's initial light outputs and the values of its initial longitudinal transmittance at 360 nm. A strong correlation was found between the emission weighted radiation induced absorption coefficients and the relative losses of the longitudinal transmittance at 440 nm. Correlations were also observed between the relative losses of crystal's light output and the relative losses of its longitudinal transmittance at 440 nm, or the emission weighted radiation induced absorption coefficients. No correlations were observed between crystal's radiation hardness and its initial longitudinal transmittance or the slope of the initial longitudinal transmittance across the band edge

Large size LYSO crystals for future high energy physics experiments

Because of their high stopping power and fast bright scintillation, cerium doped silicate based heavy crystal scintillators, such as GSO, LSO, and LYSO, have been developed for medical instruments. Their applications in high energy and nuclear physics, however, are limited by lacking high quality crystals in sufficiently large size. The optical and scintillation properties, including the transmittance, emission and excitation spectra and the light output, decay kinetics and light response uniformity, as well as their degradation under /spl gamma/-ray irradiation were measured for two long (2.5/spl times/2.5/spl times/20 cm) LYSO samples from CPI and Saint-Gobain, and were compared to a BGO sample of the same size from SIC. Possible applications for crystal calorimetry in future high energy and nuclear physics experiments are discussed

A Radiation Damage and Recovery Study for Lead Tungstate Crystals from BTCP and SIC

This paper presents result of a study on radiation damage and recovery for lead tungstate crystals produced at BTCP and SIC. Correlations were observed between initial light output and initial longitudinal transmittance at 360 nm, between the loss of longitudinal transmittance at 440 nm and the loss of light output, and between radiation damages levels at different dose rates. No correlations, however, were found between crystal’s initial optical properties and radiation hardness. Excellent linearity was observed between the variations of crystal’s light output and its longitudinal transmittance at 440 nm in several cycles of irradiation followed by recovery, indicating these PWO crystals can be monitored in situ at LHC

Direct observation of ultrafast thermal and non-thermal lattice deformation of polycrystalline Aluminum film

The dynamics of thermal and non-thermal lattice deformation of nanometer thick polycrystalline aluminum film has been studied by means of femtosecond (fs) time-resolved electron diffraction. We utilized two different pump wavelengths: 800 nm, the fundamental of Ti: sapphire laser and 1250 nm generated by a home-made optical parametric amplifier(OPA). Our data show that, although coherent phonons were generated under both conditions, the diffraction intensity decayed with the characteristic time of 0.9+/-0.3 ps and 1.7+/-0.3 ps under 800 nm and 1250 nm excitation, respectively. Because the 800 nm laser excitation corresponds to the strong interband transition of aluminum due to the 1.55 eV parallel band structure, our experimental data indicate the presence of non-thermal lattice deformation under 800 nm excitation, which occurs on a time-scale that is shorter than the thermal processes dominated by electron-phonon coupling under 1250 nm excitation

Interaction between Nobiliside-a and lipid bilayers

Nobiliside A (Nob) is a new triterpenoid saponin first discovered and isolated from the Holothuria nobilis with chemical molecular structure of C54H87O26 SNa. Extracorporeal antitumor test showed that Nob may be a new category of effective anticancer medicine which had excellent cytotoxicity as well as inhibited vascular endothelial cell (VEC) proliferation and migration in vitro and chicken chorioallantoic membrane (CAM) angiogenesis in vivo at a lower dose. Unfortunately, the clinical application of Nob was severely limited by the low bioavailability of Nob after oral administration, and highly toxic especially heart toxicity and the ability causing hemolysis of blood cells after intravenous injection. To reduce the hemolysis and toxicity of Nob after intravenous injection, liposomes were used as its carriers and good effect was acquired in our previous study. During the preparation and study of Nob liposomes, we found that Nob liposomes had high encapsulation efficiency (EE), which nearly 100 % and good stability. It was proposed that there would be strong interaction between Nob and lipid bilayers, which would affect the EE, the stability, pharmacokinetics, pharmacodynamics and even the toxicity of the drug. Thus, fourier transformer infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), fluoroscense spectroscopy were used to study the interaction between Nob and lipid bilayers. The results showed that there was a strong interaction between Nob and both phospholipids (PL) and cholesterol (CH) in lipid bilayers, and the interaction between Nob and CH was stronger than that between Nob and PL. There was also interaction between PL and CH, which would be decreased when Nob existed. Thus, the reason of Nob liposomes having high EE and good stability could be infered from the study. In fluoroscense spectroscopy study it was found that Nob could destroy calcein liposomes and lead release of the content, while Nob encapsuled in liposomes could not cause the destruction of calcein liposomes. These phenomena were different with Nob liposomes leading to the content release from red blood cells, so the mechanism of Nob liposomes decreasing the toxicity to mice and hemolysis in vitro should be further studied.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Impact of Climate Change on Canadian Water Resources: A Continental-Scale Hydrologic Modelling Study Using Multiple RCM Projections

Evidence of climate change is mounting and there is nowadays an increasing international scientific consensus that current climate change is, in part, induced by anthropogenic emissions of greenhouse gases. Climate change will have significant impacts on the water cycle and hence on both quantity and quality of our limited and valuable water resources. Quantifying the potential hydrologic responses to a range of plausible future climates is the key for assessing the linkage between future climate change and water resources. There have been a large number of hydrologic impact studies addressing this challenging issue in the literature. Most of the studies, however, bear one or more of the following deficiencies: 1) global-scale GCM data are directly used as the forcing for the hydrologic model; 2) Future climate projections are derived based on only one emission scenario; 3) Future climate projections are derived based on only one climate model; 4) The future climate scenario is hypothetical, e.g. based on an arbitrary assumed change factor relative to the present-day climate scenario, instead of using a climate model output; 5) The hydrologic model does not simulate both surface water and groundwater in a physically-based manner and 6) The model domain is too small, e.g. a catchment or river basin scale. In this study, a continental-scale modelling framework free of the above caveats is developed to predict the potential future climate change effects on Canadian water resources. To the best of my knowledge, this study is one of the first of its kind in the literature. HydroGeoSphere, a physically-based fully-coupled surface-subsurface flow and transport simulator, is selected to perform hydrologic modelling in this study. The study domain covers the Northern half of North America continent, consisting of six super watersheds. The study domain is discretized into a triangular mesh, with refinement along hydrologically important features. After discretization, the 3D prism grid has 15 vertical layers and about one million nodes. In total 11 hydrostratigraphic units are represented in the 3D geology model which is constructed based on sediment thickness, permafrost distribution and surficial geological data. In this work, net precipitation data are used as the forcing to drive the HydroGeoSphere model. Present-day net precipitation is computed using observed total precipitation data in conjunction with high-resolution RCM outputs. The hydrologic model is initially used to reproduce present-day hydrology and the simulation results show good agreement against observed hydrologic data. After calibration and validation, the HydroGeoSphere model is used to assess hydrologic impacts of future climate changes assuming that, except for net precipitation, all parameters and boundary conditions remain unchanged. Multiple high-resolution outputs obtained with three reputable RCMs (CRCM, HRM and WRF) under two IPCC emission scenarios (A2 and A1B) are used to estimate future net precipitation. This is determined based on the RCM projected changes between the future periods (2011-2040, 2041-2070 or 2071-2100) and the control period (1971-2000) using a hybrid approach. The long-term evolution of hydrologic responses to future climate changes over the 21st century is explored using three 30-year-period CRCM data. Efforts are also made to quantify the two main uncertainties in simulation results that are associated with the climate models and the emission scenarios using four RCM outputs for the period of 2041-2070. Simulation results suggest that rivers in the North are likely to observe a steady increase in streamflow and streamflows of the major rivers in the South are predicted to remain more or less unchanged over the 21st century. The water table is predicted to rise in mountainous regions in the NW, decrease in the prairies and remain relatively unchanged for most of the remaining areas where the terrains are relatively flat. Sensitivity analyses indicate that the hydrologic responses are more sensitive to the different climate models than they are to the different emission scenarios. This modelling study demonstrates that a fully-coupled surface and subsurface flow hydrologic simulation at the continental-scale is possible and could be made operational. The good skill exhibited by the HydroGeoSphere model for the present-day hydrology simulation suggests that high-resolution RCM outputs are effective surrogate data for actual ET estimation when observed climate data are insufficiently available. Based on the RCM projections used in this work, future climate may have significant hydrologic impacts in some regions of this study domain such as in the North and the prairies. However, simulation results should be interpreted with cautions due to the inconsistencies and sometimes even opposite predictions between the outputs of different RCMs