Determination and Optimisation of Descriptor Values of Safrole by Gas-Liquid Chromatographic Methods and Liquid-Liquid Partition Systems

In recent years, accumulation of harmful organic chemicals in various environmental and biological compartments causes regrettable harmful effects to humans and ecosystems. Therefore, determining their distribution levels and controlling their risks in these compartments is important for environmental risk assessment procedures. However, experimental determination of their distribution for dose-response and exposure assessments needs a large amount of economical, technical, and human resources. Moreover, such requirements are difficult to afford by developing countries like Sri Lanka. As a solution to this problem, Quantitative-Structure Property Relationship (QSPR) method can be used to establish a quantitative relationship between the structures of the compounds and their chemical and physical properties. In this study, Abraham’s solvation parameter model, was used as the QSPR together with experimental values to determine descriptor values for safrole. Safrole is a harmful organic chemical which is used as a flavouring agent, a fragrance agent, and a raw material in many industries including the drug and perfumery. Because sufficient levels of safrole were identified as a carcinogen, the use of safrole was prohibited by United States Food and Drug Administration (US FDA) since 1970. According to the food additive regulations, safrole in soft drinks, beverages, and food must be lower than 1 μg ml-1 .Safrole is a constituent compound of some spices which are being used for commercial beverage productions and is also used widely in the perfumery industry. Here, descriptor values for safrole were determined using gas-liquid chromatographic retention factors combined with liquid-liquid partition coefficients. Isothermal retention factors were determined at 20o C intervals over the temperature range of 60o C to 160o C for poly (cyanopropylphenyldimethylsiloxane) stationary phase with 14% cyanopropylphenyl monomer. Previously measured retention factors for poly (dimethyldiphenylsiloxane) stationary phase with 5% diphenylsiloxane monomer were optimized in this research study, over the temperature range of 80o C to 280o C. Partition coefficients of safrole were determined using eight different totally organic partition systems (n-heptane-formamide, n-heptane-methanol, n-heptane-n,n-dimethyl formamide, n-heptanetrifluoroethanol, n-heptane-dimethyl sulfoxide, isopentyl ether-ethylene glycol, isopentyl ether-dimethylsulfoxide, and n-hexane-acetonitrile). Then the descriptor values were determined using Solver Algorithm in excel using the measured retention factors and partition coefficients. Solver is an algorithm which assigns the values for the descriptors such that the standard deviation between the experimental solute property and the calculated solute property would be minimum. Determined descriptor values for safrole using these stationary phases and solvent systems are E=1.108, S=1.123, A=0.000, L=5.340, B=0.174, B (0)=0.365 and V=1.246. Validity of the descriptors were tested with theoretical models. The determined descriptor values have a small standard deviation (0.068). Therefore, the determined descriptor values will be useful in determining the distribution level of safrole in environmental compartments.Keywords: QSPR, Solvation parameter model, Safrole, Gas-liquid chromatography, Liquid-liquid partition system

Instability of vortex array and transitions to turbulent states in rotating helium II

We consider superfluid helium inside a container which rotates at constant angular velocity and investigate numerically the stability of the array of quantized vortices in the presence of an imposed axial counterflow. This problem was studied experimentally by Swanson {\it et al.}, who reported evidence of instabilities at increasing axial flow but were not able to explain their nature. We find that Kelvin waves on individual vortices become unstable and grow in amplitude, until the amplitude of the waves becomes large enough that vortex reconnections take place and the vortex array is destabilized. The eventual nonlinear saturation of the instability consists of a turbulent tangle of quantized vortices which is strongly polarized. The computed results compare well with the experiments. Finally we suggest a theoretical explanation for the second instability which was observed at higher values of the axial flow

Simple Fluids with Complex Phase Behavior

We find that a system of particles interacting through a simple isotropic potential with a softened core is able to exhibit a rich phase behavior including: a liquid-liquid phase transition in the supercooled phase, as has been suggested for water; a gas-liquid-liquid triple point; a freezing line with anomalous reentrant behavior. The essential ingredient leading to these features resides in that the potential investigated gives origin to two effective core radii.Comment: 7 pages including 3 eps figures + 1 jpeg figur

The approach to vortex reconnection

We present numerical solutions of the Gross--Pitaevskii equation corresponding to reconnecting vortex lines. We determine the separation of vortices as a function of time during the approach to reconnection, and study the formation of pyramidal vortex structures. Results are compared with analytical work and numerical studies based on the vortex filament method.Comment: 11 pages, 9 figure

Small-Scale Vertical Movements of Summer Flounder Relative to Diurnal, Tidal, and Temperature Changes

Observation of animal movements on small spatial scales provides a means to understand how large-scale species distributions are established from individual behavioral decisions. Small-scale vertical movements of 14 Summer Flounder Paralichthys dentatus residing in Chesapeake Bay were observed by using depth data collected with archival tags. A generalized linear mixed model was employed to examine the relationship between these vertical movements and environmental covariates such as tidal state, time of day, lunar phase, and temperature. Vertical movements increased with warming water temperatures, and this pattern was most apparent at night and during rising and falling tides. Fish generally exhibited greater vertical movements at night, but the difference between vertical movements in the day and those at night decreased as fish increased in size. Results from this study fill a void in understanding the small-scale movements of Summer Flounder and could be incorporated into individual-based models to investigate how species distributions develop in response to environmental conditions

Normal fluid eddies in the thermal counterflow past a cylinder

A recent Particle Image Velocimetry (PIV) experiment in He II counterflow around a cylindrical obstacle showed the existence of apparently stationary normal fluid ddies both downstream (at the rear) and upstream (in front) of the cylinder. This rather surprising result does not have an analogue in experimental observations of classical fluid flows. We suggest that the explanation for the apparent stability of such eddies can be provided entirely from the viewpoint of classical fluid dynamics. We also discuss a possible connection between the emergence of the normal fluid eddies and the polarization of the vortex tangle in superfluid.Comment: submitte

Particles-vortex interactions and flow visualization in He4

Recent experiments have demonstrated a remarkable progress in implementing and use of the Particle Image Velocimetry (PIV) and particle tracking techniques for the study of turbulence in He4. However, an interpretation of the experimental data in the superfluid phase requires understanding how the motion of tracer particles is affected by the two components, the viscous normal fluid and the inviscid superfluid. Of a particular importance is the problem of particle interactions with quantized vortex lines which may not only strongly affect the particle motion, but, under certain conditions, may even trap particles on quantized vortex cores. The article reviews recent theoretical, numerical, and experimental results in this rapidly developing area of research, putting critically together recent results, and solving apparent inconsistencies. Also discussed is a closely related technique of detection of quantized vortices negative ion bubbles in He4.Comment: To appear in the J Low Temperature Physic

Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)

BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems