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Selected AbstractsInfluence of silica gel in production of diacylglycerol via enzymatic glycerolysis of palm oleinEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 6 2009Chiou Moi Yeoh Abstract Enzymatic glycerolysis was explored in this paper for the production of diacylglycerol (DAG) oils from palm olein. Three commercial enzymes, Lipozyme TL,IM, Lipozyme RM,IM and Novozym 435 were used for their ability to synthesize DAG in a solvent-free system. Novozym 435 was found to be the more effective enzyme, resulting in a high DAG production even in the absence of an adsorbent such as silica gel. The yields of DAG were between 43 and 50,wt-%. Lipozyme TL,IM and RM,IM, being supported on hydrophilic materials, require an adsorbent to allow slow release of glycerol for reaction with the enzyme and oil. In the absence of silica, no reaction was observed. The success of the reaction is therefore very dependent on the amount of silica used. The yields of DAG using Lipozyme TL,IM and RM,IM were 52 and 45,wt-%, respectively. In addition, the degree of reduction in tocopherols and tocotrienols appeared correlated with the efficacy of the glycerolysis reaction. Changes in the slip melting points and solid fat contents of the products are indicative of the reaction occurring. [source] Sensitivity of multi-coil frequency domain electromagnetic induction sensors to map soil magnetic susceptibilityEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2010D. Simpson Magnetic susceptibility is an important indicator of anthropogenic disturbance in the natural soil. This property is often mapped with magnetic gradiometers in archaeological prospection studies. It is also detected with frequency domain electromagnetic induction (FDEM) sensors, which have the advantage that they can simultaneously measure the electrical conductivity. The detection level of FDEM sensors for magnetic structures is very dependent on the coil configuration. Apart from theoretical modelling studies, a thorough investigation with field models has not been conducted until now. Therefore, the goal of this study was to test multiple coil configurations on a test field with naturally enhanced magnetic susceptibility in the topsoil and with different types of structures mimicking real archaeological features. Two FDEM sensors were used with coil separations between 0.5 and 2 m and with three coil orientations. First, a vertical sounding was conducted over the undisturbed soil to test the validity of a theoretical layered model, which can be used to infer the depth sensitivity of the coil configurations. The modelled sounding values corresponded well with the measured data, which means that the theoretical models are applicable to layered soils. Second, magnetic structures were buried in the site and the resulting anomalies measured to a very high resolution. The results showed remarkable differences in amplitude and complexity between the responses of the coil configurations. The 2-m horizontal coplanar and 1.1-m perpendicular coil configurations produced the clearest anomalies and resembled best a gradiometer measurement. [source] Molecular dynamics study on effects of surface structures in nanometer scale on energy transfer from fluid to surfaceHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2005Masahiko Shibahara Abstract Energy transfer from fluid to surface was calculated numerically by using the classical molecular dynamics method in order to investigate the effects of surface structures from 0.1 nm to 10 nm on surface energy transfer. Surface structures on a constant surface area were composed of several hundred atoms having various potential energy parameters, in other words, thermal properties. The upper region in the calculation domain was controlled at a constant temperature and one of the solid atomic layers at the lower region in the calculation domain was controlled at another constant temperature to create a temperature gradient in the calculation system. Energy transfer to the surface was very dependent on surface nanometer scale structures in that affected the static structure and the dynamic behaviors of fluid molecules in the vicinity of the surface. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(3): 171,179, 2005; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/htj.20055 [source] Energy and exergy analysis of a double absorption heat transformer operating with water/lithium bromideINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009H. Martínez Abstract In the present study, the first and second law of thermodynamics have been used to analyze in detail the performance of a double absorption (lift) heat transformer operating with the water,lithium bromide mixture. A mathematical model was developed to estimate the coefficient of performance (COP), the exergy coefficient of performance (ECOP), the total exergy destruction in the system (,TD) and the exergy destruction (,D) in each one of the main components, as a function of the system temperatures, the efficiency of the economizer (EFEC), the gross temperature lift and flow ratio (FR). The results showed that the generator is the component with the highest irreversibilities or exergy destruction contributing to about 40% of the total exergy destruction in the whole system, reason why this component should be carefully designed and optimized. The results also showed that the COP and ECOP increase with increase in the generator, the evaporator and the absorber,evaporator temperatures and decrease with the absorber and condenser temperatures. Finally, it was observed that the COP and ECOP are very dependent of the FR and the economizer efficiency (EFEC) values. Also the optimum operating region of the analyzed system is shown in the present study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Detection of Cryptosporidium parvum in lettuceINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2007John E. Moore Summary Human cryptosporidiosis has emerged as an important gastrointestinal infection in the 1990s as a result of the ingestion of mainly contaminated water and to a lesser extent foodstuffs containing the protozoan parasite, Cryptosporidium parvum. This pathogen has particular clinical significance for immunocompromised persons, including AIDS patients and cancer patients receiving toxic chemotherapeutic drug regimens. There have been a limited number of studies performed examining the occurrence of the parasite on vegetables, including lettuce. Detection rates are very dependent on the laboratory isolation technique employed and has ranged from 1.2% to 14.5%. Current best practice of laboratory recovery, isolation and detection methods include detergent removal, oocysts concentration by immunomagnetic separation, followed by a combination of immunofluorescent microscopy and a nested PCR approach. Employment of contaminated non-potable water in the production of vegetables, particularly lettuce, may represent an important potential source of entry of pathogens into food processing and the human food chain. Given that lettuce is an important constituent of hamburger dressing, and the size of the fast-food industry, where lettuce is an important constituent, horticultural producers of lettuce should therefore place special emphasis on developing suitable and efficient Hazard Analysis Critical Control Point strategies for the critical control of oocysts depending on the type of unit operation employed and vegetable being processed. This review aims to examine (i) the incidence of C. parvum in vegetables, particularly lettuce and (ii) laboratory detection methods for the isolation and identification of this parasite from lettuce. [source] Effect of Cation Doping on the Superplastic Flow in Yttria-Stabilized Tetragonal Zirconia PolycrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2001Junpei Mimurada The superplastic characteristics of various cation-doped yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) were examined. For 1 mol% cation doping the true stress of Y-TZP is very dependent on the ionic radii of the doped cations; for instance, smaller cation radii give rise to lower true stress when compared with the other compositions for the same grain size, strain rate, and testing temperature. The altered true stress level must be due to the change in diffusivity of the accommodation process for grain boundary sliding caused by the addition of cations in ZrO2. The strain to failure of the doped zirconia is affected by both ionic radius and valence of the dopant cations. [source] Immobilization of Candida antarctica lipase B on Polystyrene NanoparticlesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2010Nemanja Mileti Abstract Polystyrene (PS) nanoparticles were prepared via a nanoprecipitation process. The influence of the pH of the buffer solution used during the immobilization process on the loading of Candida antarctica lipase B (Cal-B) and on the hydrolytic activity (hydrolysis of p -nitrophenyl acetate) of the immobilized Cal-B was studied. The pH of the buffer solution has no influence on enzyme loading, while immobilized enzyme activity is very dependent on the pH of adsorption. Cal-B immobilized on PS nanoparticles in buffer solution pH 6.8 performed higher hydrolytic activity than crude enzyme powder and Novozyme 435. [source] Atmospheric tides over the Pyrenees: observational study and numerical simulationTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 650 2010J. Díaz de Argandoña Abstract Barometric tides around the Pyrenees mountain range are analyzed by means of synoptic surface-station data recorded during one year, surface data from the Pyrenees Experiment (PYREX) and the CRA/LA Very High Frequency (VHF) wind profiler installed in the north of the range. Tides are decomposed into their diurnal and semi-diurnal components. Diurnal tides show a strong non-migrating component and are very dependent on local conditions. Semi-diurnal tides are more homogeneous and present a north,south asymmetry, also noted in the Alps. This cross-range asymmetry could be related to some interference effect caused by the mountain range in the migrating semi-diurnal tide wave. The asymmetry of the diurnal component presents a very strong seasonal variation, probably related to local diabatic effects. A three-month long simulation has been carried out with the National Center for Atmospheric Research's Weather Research and Forecasting (WRF) limited-area model to try to reproduce the tide structure. The validation of the results with wind-profiler data shows reasonable agreement with the observed diurnal tide and poorer results for the semi-diurnal component. At surface level, however, the model reproduces some of the features of the observed semi-diurnal tide, and especially the cross-range asymmetry. Copyright © 2010 Royal Meteorological Society [source] Modelling the wet deposition of reduced nitrogen over the British Isles using a Lagrangian multi-layer atmospheric transport modelTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 606 2005N. Fournier Abstract Wet deposition of reduced nitrogen is estimated for the United Kingdom using a Lagrangian long-term, long-range atmospheric transport model. Such long-range transport models are used to develop emission-control strategies to combat environmental acidification in the sensitive regions of the United Kingdom and Europe. These models currently consider the wet deposition as a loss term using scavenging rates and a simple seeder,feeder effect. The seeder,feeder effect is assumed to be the main process producing orographic precipitation since the majority of British Isles annual rainfall falls in frontal events. This paper focuses on the analysis of different parametrizations of the removal process by wet deposition. It is shown that the seeder,feeder effect is very dependent on flow direction. Therefore, a model of directional orographic enhancement of precipitation is developed to simulate this effect. A revised formulation of the wet deposition parametrization is suggested, incorporating the directional orographic precipitation produced with this model. This new formulation also takes into account the larger concentrations of ions dissolved in rain water measured in mountainous areas. Moreover, a new representation of the wet deposition process is developed by considering explicitly the mixing layer's depth calculated in the model. The results from the atmospheric model, with these revised parametrizations of the wet deposition, are then compared with measured wet deposition of reduced nitrogen. Firstly, with the new directional orographic rainfall, the modelled United Kingdom reduced nitrogen wet deposition budget is still underestimated but an increased correlation with measurements is obtained. Secondly, the inclusion of the calculated mixing layer's depth leads to a considerable improvement in the modelled reduced nitrogen wet deposition budget compared with measurements. Copyright © 2005 Royal Meteorological Society. [source] Importance of Uniform Heparin Coating on BiopolymersARTIFICIAL ORGANS, Issue 3 2000Patrícia Da Luz Moreira Abstract: Cardiopulmonary surgeries need connectors for extracorporeal circulation. The patient's blood in contact with the tube surfaces modifies its plasmatic proteins, promotes platelet aggregation, and activates the complement system, unleashing thrombus formation. Thus, it becomes necessary for an anticoagulant to keep the circuit free from these events. Heparin is the anticoagulant used even after reports about its disadvantages. Platelet adherence seems to be very dependent on the quality from the surfaces that can promote cellular proliferation, aggregation, and thrombosis. In this study, we compare the quality of the heparin-coated and uncoated surfaces. We used a blood cell culture and scanning electron microscopy (SEM) to visualize the platelet aggregation. It was concluded that there are groove areas that permit platelet adherence, and if they are not coated totally by the heparin, aggregation still occurs although in lower scale than on the uncoated tubes. [source] OUTLYING OBSERVATIONS AND MISSING VALUES: HOW SHOULD THEY BE HANDLED?CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2008John Ludbrook SUMMARY 1The problems of, and best solutions for, outlying observations and missing values are very dependent on the sizes of the experimental groups. For original articles published in Clinical and Experimental Pharmacology and Physiology during 2006,2007, the range of group sizes ranged from three to 44 (,small groups'). In surveys, epidemiological studies and clinical trials, the group sizes range from 100s to 1000s (,large groups'). 2How can one detect outlying (extreme) observations? The best methods are graphical, for instance: (i) a scatterplot, often with mean±2 s; and (ii) a box-and-whisker plot. Even with these, it is a matter of judgement whether observations are truly outlying. 3It is permissable to delete or replace outlying observations if an independent explanation for them can be found. This may be, for instance, failure of a piece of measuring equipment or human error in operating it. If the observation is deleted, it can then be treated as a missing value. Rarely, the appropriate portion of the study can be repeated. 4It is decidedly not permissable to delete unexplained extreme values. Some of the acceptable strategies for handling them are: (i) transform the data and proceed with conventional statistical analyses; (ii) use the mean for location, but use permutation (randomization) tests for comparing means; and (iii) use robust methods for describing location (e.g. median, geometric mean, trimmed mean), for indicating dispersion (range, percentiles), for comparing locations and for regression analysis. 5What can be done about missing values? Some strategies are: (i) ignore them; (ii) replace them by hand if the data set is small; and (iii) use computerized imputation techniques to replace them if the data set is large (e.g. regression or EM (conditional Expectation, Maximum likelihood estimation) methods). 6If the missing values are ignored, or even if they are replaced, it is essential to test whether the individuals with missing values are otherwise indistinguishable from the remainder of the group. If the missing values have not occurred at random, but are associated with some property of the individuals being studied, the subsequent analysis may be biased. [source] | |||||||||||||||||||