WorldWideScience

Sample records for bulk speciation methods

  1. Speciation and distribution of copper in a mining soil using multiple synchrotron-based bulk and microscopic techniques.

    Science.gov (United States)

    Yang, Jianjun; Liu, Jin; Dynes, James J; Peak, Derek; Regier, Tom; Wang, Jian; Zhu, Shenhai; Shi, Jiyan; Tse, John S

    2014-02-01

    Molecular-level understanding of soil Cu speciation and distribution assists in management of Cu contamination in mining sites. In this study, one soil sample, collected from a mining site contaminated since 1950s, was characterized complementarily by multiple synchrotron-based bulk and spatially resolved techniques for the speciation and distribution of Cu as well as other related elements (Fe, Ca, Mn, K, Al, and Si). Bulk X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that soil Cu was predominantly associated with Fe oxides instead of soil organic matter. This agreed with the closest association of Cu to Fe by microscopic X-ray fluorescence (U-XRF) and scanning transmission X-ray microscopy (STXM) nanoanalysis, along with the non-occurrence of photoreduction of soil Cu(II) by quick Cu L3,2-edge XANES spectroscopy (Q-XANES) which often occurs when Cu organic complexes are present. Furthermore, bulk-EXAFS and STXM-coupled Fe L3,2-edge nano-XANES analysis revealed soil Cu adsorbed primarily to Fe(III) oxides by inner-sphere complexation. Additionally, Cu K-edge μ-XANES, L3,2-edge bulk-XANES, and successive Q-XANES results identified the presence of Cu2S rather than radiation-damage artifacts dominant in certain microsites of the mining soil. This study demonstrates the great benefits in use of multiple combined synchrotron-based techniques for comprehensive understanding of Cu speciation in heterogeneous soil matrix, which facilitates our prediction of Cu reactivity and environmental fate in the mining site.

  2. Strontium speciation during reaction of kaolinite with simulated tank-waste leachate: bulk and microfocused EXAFS analysis.

    Science.gov (United States)

    Choi, Sunkyung; O'Day, Peggy A; Rivera, Nelson A; Mueller, Karl T; Vairavamurthy, Murthy A; Seraphin, Supapan; Chorover, Jon

    2006-04-15

    Radioactive strontium (90Sr) is an important constituent of the complex wastes from past nuclear weapons production and has been stored in underground tanks at U.S. DOE sites (e.g., Hanford, WA). Using bulk and microfocused EXAFS spectroscopy, we examined temporal changes in solid-phase Sr speciation in kaolinite samples reacted for 1-369 d with high-pH, high ionic strength synthetic tank-waste leachate containing Sr(2+) and Cs(+) at 10(-3) mol kg(-1). Analyses of bulk EXAFS spectra showed that Sr initially forms a precipitate by 7 d with a local structure similar to SrCO(3-) (s). At 33 d, microfocused EXAFS of individual particles in one sample revealed a mixture of hydrated and dehydrated Sr associated with neoformed sodalite-type phases. At aging times of 93 d and longer, bulk EXAFS spectra and supporting characterizations indicated nonexchangeable Sr with a local structure consistent with incorporation into increasingly crystalline aluminosilicate particles, particularly sodalite. These experimental studies suggest that irreversible trapping of radionuclides occurs if they are present during the formation and aging of feldspathoid alteration products of local Si-bearing sediment minerals. This may serve as an effective contaminant sequestration mechanism at sites such as Hanford.

  3. Evaluation of mercury speciation by EPA (Draft) Method 29

    Energy Technology Data Exchange (ETDEWEB)

    Laudal, D.L.; Heidt, M.K. [Energy & Environmental Research Center, Grand Forks, ND (United States); Nott, B. [Electric Power Research Institute, Palo Alto, CA (United States)

    1995-11-01

    The 1990 Clean Air Act Amendments require that the U.S. Environmental protection Agency (EPA) assess the health risks associated with mercury emissions. Also, the law requires a separate assessment of health risks posed by the emission of 189 tract chemicals (including mercury) for electric utility steam-generating units. In order to conduct a meaningful assessment of health and environmental effects, we must have, among other things, a reliable and accurate method to measure mercury emissions. In addition, the rate of mercury deposition and the type of control strategies used may depend upon the type of mercury emitted (i.e., whether it is in the oxidized or elemental form). It has been speculated that EPA (Draft) Method 29 can speciate mercury by selective absorption; however, this claim has yet to be proven. The Electric Power Research Institute (EPRI) and the U.S. Department of Energy (DOE) have contracted with the Energy & Environmental Research Center (EERC) at University of North Dakota to evaluate EPA (Draft) Method 29 at the pilot-scale level. The objective of the work is to determine whether EPA (Draft) Method 29 can reliably quantify and speciate mercury in the flue gas from coal-fired boilers.

  4. A novel colorimetric method for field arsenic speciation analysis

    Institute of Scientific and Technical Information of China (English)

    Shan Hu; Jinsuo Lu; Chuanyong Jing

    2012-01-01

    Accurate on-site determination of arsenic (As) concentration as well as its speciation presents a great environmental challenge especially to developing countries.To meet the need of routine field monitoring,we developed a rapid colorimetric method with a wide dynamic detection range and high precision.The novel application of KMnO4 and CH4N2S as effective As(Ⅲ) oxidant and As(Ⅴ) reductant,respectively,in the formation of molybdenum blue complexes enabled the differentiation of As(Ⅲ) and As(Ⅴ).The detection limit of the method was 8 μg/L with a linear range (R2 =0.998) of four orders of magnitude in total As concentrations.The As speciation in groundwater samples determined with the colorimetric method in the field were consistent with the results using the high performance liquid chromatography atomic fluorescence spectrometry,as evidenced by a linear correlation in paired analysis with a slope of 0.9990-0.9997 (p < 0,0001,n =28).The recovery of 96%-116% for total As,85%-122% for As(Ⅲ),and 88%-127% for As(Ⅴ) were achieved for groundwater samples with a total As concentration range 100-800 μg/L,The colorimetric result showed that 3.61 g/L As(Ⅲ) existed as the only As species in a real industrial wastewater,which was in good agreement with the HPLC-AFS result of 3.56 g/L As(Ⅲ),No interference with the color development was observed in the presence of sulfate,phosphate,silicate,humic acid,and heavy metals from complex water matrix.This accurate,sensitive,and easy-to-use method is especially suitable for field As determination.

  5. On methods of estimating cosmological bulk flows

    CERN Document Server

    Nusser, Adi

    2015-01-01

    We explore similarities and differences between several estimators of the cosmological bulk flow, $\\bf B$, from the observed radial peculiar velocities of galaxies. A distinction is made between two theoretical definitions of $\\bf B$ as a dipole moment of the velocity field weighted by a radial window function. One definition involves the three dimensional (3D) peculiar velocity, while the other is based on its radial component alone. Different methods attempt at inferring $\\bf B$ for either of these definitions which coincide only for a constant velocity field. We focus on the Wiener Filtering (WF, Hoffman et al. 2015) and the Constrained Minimum Variance (CMV,Feldman et al. 2010) methodologies. Both methodologies require a prior expressed in terms of the radial velocity correlation function. Hoffman et al. compute $\\bf B$ in Top-Hat windows from a WF realization of the 3D peculiar velocity field. Feldman et al. infer $\\bf B$ directly from the observed velocities for the second definition of $\\bf B$. The WF ...

  6. Characterization of bulk superconductors through EBSD methods

    Science.gov (United States)

    Koblischka, M. R.; Koblischka-Veneva, A.

    2003-10-01

    The application of electron backscatter diffraction (EBSD) technique to bulk high- Tc superconductors is presented and reviewed. Due to the ceramic nature and the complex crystallographic unit cells of the perovskite-type high- Tc superconductors, the EBSD analysis is not yet as common as it deserves. We have successfully performed EBSD analysis on a variety of high- Tc compounds and samples including polycrystalline YBCO (pure and doped by alkali metals), melt-textured YBCO, thin and thick films of YBCO; the “green phase” Y 2BaCuO 5, thin film and melt-textured NdBa 2Cu 3O x and Bi-2212 single crystals and tapes. It is shown that the surface preparation of the samples is crucial due to the small information depth (up to 100 nm) of the EBSD technique. High quality Kikuchi patterns are the requirement in order to enable the automated EBSD mapping, which yields phase distributions, individual grain orientations and the misorientation angle distribution. The results can be presented in form of mappings, as charts, and as pole figures. These informations are required for a better understanding of the growth mechanism(s) of bulk high- Tc superconductors intended for applications.

  7. Carbon nanotubes grown on bulk materials and methods for fabrication

    Science.gov (United States)

    Menchhofer, Paul A.; Montgomery, Frederick C.; Baker, Frederick S.

    2011-11-08

    Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

  8. Positron methods for the study of defects in bulk materials

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard

    1995-01-01

    The basic principles of positron annihilation physics are briefly discussed and the three most important experimental techniques used for bulk studies are described (i.e. positron lifetime, angular correlation, Doppler broadening). Several examples of the use of the positron methods are discussed...

  9. Fabrication of bulk metallic glasses by centrifugal casting method

    OpenAIRE

    R. Nowosielski; R. Babilas

    2007-01-01

    Purpose: The aim of the present work is characterization of the centrifugal casting method, apparatus andproduced amorphous materials, which are also known as bulk metallic glassesDesign/methodology/approach: The studied centrifugal casting system consists of two main parts: castingapparatus and injection system of molten alloy. The described centrifugal casting method was presented bypreparing a casting apparatus “CentriCast – 5”. The apparatus includes a cylindrical copper mold, which isrot...

  10. Probing bulk defect energy bands using generalized charge pumping method

    Science.gov (United States)

    Masuduzzaman, Muhammad; Weir, Bonnie; Alam, Muhammad Ashraful

    2012-04-01

    The multifrequency charge pumping (CP) technique has long been used to probe the density of defects at the substrate-oxide interface, as well as in the bulk of the oxide of MOS transistors. However, profiling the energy levels of the defects has been more difficult due to the narrow scanning range of the voltage of a typical CP signal, and the uncertainty associated with the defect capture cross-section. In this paper, we discuss a generalized CP method that can identify defect energy bands within a bulk oxide, without requiring separate characterization of the defect capture cross-section. We use the new technique to characterize defects in both fresh and stressed samples of various dielectric compositions. By quantifying the way defects are generated as a function of time, we gain insight into the nature of defect generation in a particular gate dielectric. We also discuss the relative merits of voltage, time, and other variables of CP to probe bulk defect density, and compare the technique with related characterization approaches.

  11. A new method for antimony speciation in plant biomass and nutrient media using anion exchange cartridge.

    Science.gov (United States)

    Tisarum, Rujira; Ren, Jing-Hua; Dong, Xiaoling; Chen, Hao; Lessl, Jason T; Ma, Lena Q

    2015-11-01

    A selective separation method based on anion exchange cartridge was developed to determine antimony (Sb) speciation in biological matrices by graphite furnace atomic absorption spectrophotometry (GFAAS). The selectivity of the cartridge towards antimonite [Sb(III)] and antimonate [Sb(V)] reversed in the presence of deionized (DI) water and 2mM citric acid. While Sb(V) was retained by the cartridge in DI water, Sb(III) was retained in citric acid media. At pH 6, Sb(III) and Sb(V) formed Sb(III)- and Sb(V)-citrate complexes, but the cartridge had higher affinity towards the Sb(III)-citrate complex. Separation of Sb(III) was tested at various concentrations in fresh and spent growth media and plant tissues. Our results showed that cartridge-based Sb speciation was successful in plant tissues, which was confirmed by HPLC-ICP-MS. The cartridge retained Sb(III) and showed 92-104% Sb(V) recovery from arsenic hyperaccumulator Pteris vittata roots treated with Sb(III) and Sb(V). The cartridge procedure is an effective alternative for Sb speciation, offering low cost, reproducible results, and simple Sb analysis using GFAAS.

  12. Stability-indicating HPLC method for posaconazole bulk assay.

    Science.gov (United States)

    Garcia, Cássia V; Costa, Gislaine R; Mendez, Andreas S L

    2012-01-01

    A stability-indicating liquid chromatographic (LC) method was developed for the determination of posaconazole in bulk. Chromatographic separation was achieved using an isocratic elution in a reversed-phase system, with a mobile phase composed of methanol-water (75:25, v/v), at 1.0 mL min(-1) flow. Samples were exposed to degradation under thermal, oxidative and acid/basic conditions, and no interference in the analysis was observed. System suitability was evaluated and results were satisfactory (N = 4,900.00 tailing factor 1.04; RSD between injections = 0.65). The retention time of posaconazole was about 8.5 min and the method was validated within the concentration range 5-60 μg mL(-1) (r = 0.9996). Adequate results were obtained for repeatability (RSD % = 0.86-1.22), inter-day precision (RSD % = 1.21) and accuracy (98.13% mean recovery). Robustness was also determined to be satisfactory after evaluation. The proposed method was successfully applied to posaconazole bulk quantification, showing the method is useful for determination of the drug in routine analysis.

  13. Stability-Indicating HPLC Method for Posaconazole Bulk Assay

    OpenAIRE

    GARCIA, Cássia; COSTA, Gislaine; MENDEZ, Andreas

    2012-01-01

    A stability-indicating liquid chromatographic (LC) method was developed for the determination of posaconazole in bulk. Chromatographic separation was achieved using an isocratic elution in a reversed-phase system, with a mobile phase composed of methanol-water (75:25, v/v), at 1.0 mL min−1 flow. Samples were exposed to degradation under thermal, oxidative and acid/basic conditions, and no interference in the analysis was observed. System suitability was evaluated and results were satisfactory...

  14. A single-reagent method for the speciation of chromium in natural waters by flame atomic absorption spectrometry based on vesicular liquid coacervate extraction

    Science.gov (United States)

    Tsogas, George Z.; Giokas, Dimosthenis L.; Vlessidis, Athanasios G.; Evmiridis, Nicholaos P.

    2004-07-01

    The concept of liquid coacervate extraction (LCE) is deployed to accomplish metal speciation after appropriate derivatization of the target metallic species. The method involves the partitioning of the hydrophobic metal chelates, produced from the reaction of Cr with APDC, in the vesicular aggregates formed from an anionic surfactant with alkaline earth metals and a cosurfactant, which are separated from the bulk aqueous phase. Under the established experimental conditions, the method offers high reproducibility, very low detection limits and recoveries in the range of 95-104%. Moreover, the method affords high tolerance for EDTA, which is used as a masking agent in order to avoid interferences from co-extracted metals. Validation of the outlined method was performed by analysing a certified reference material (BCR 544) yielding recoveries higher than 94% for both Cr oxidation states.

  15. A single-reagent method for the speciation of chromium in natural waters by flame atomic absorption spectrometry based on vesicular liquid coacervate extraction

    Energy Technology Data Exchange (ETDEWEB)

    Tsogas, George Z.; Giokas, Dimosthenis L. E-mail: dgiokas@cc.uoi.gr; Vlessidis, Athanasios G.; Evmiridis, Nicholaos P

    2004-07-30

    The concept of liquid coacervate extraction (LCE) is deployed to accomplish metal speciation after appropriate derivatization of the target metallic species. The method involves the partitioning of the hydrophobic metal chelates, produced from the reaction of Cr with APDC, in the vesicular aggregates formed from an anionic surfactant with alkaline earth metals and a cosurfactant, which are separated from the bulk aqueous phase. Under the established experimental conditions, the method offers high reproducibility, very low detection limits and recoveries in the range of 95-104%. Moreover, the method affords high tolerance for EDTA, which is used as a masking agent in order to avoid interferences from co-extracted metals. Validation of the outlined method was performed by analysing a certified reference material (BCR 544) yielding recoveries higher than 94% for both Cr oxidation states.

  16. Field and laboratory arsenic speciation methods and their application to natural-water analysis

    Science.gov (United States)

    Bednar, A.J.; Garbarino, J.R.; Burkhardt, M.R.; Ranville, J.F.; Wildeman, T.R.

    2004-01-01

    The toxic and carcinogenic properties of inorganic and organic arsenic species make their determination in natural water vitally important. Determination of individual inorganic and organic arsenic species is critical because the toxicology, mobility, and adsorptivity vary substantially. Several methods for the speciation of arsenic in groundwater, surface-water, and acid mine drainage sample matrices using field and laboratory techniques are presented. The methods provide quantitative determination of arsenite [As(III)], arsenate [As(V)], monomethylarsonate (MMA), dimethylarsinate (DMA), and roxarsone in 2-8min at detection limits of less than 1??g arsenic per liter (??g AsL-1). All the methods use anion exchange chromatography to separate the arsenic species and inductively coupled plasma-mass spectrometry as an arsenic-specific detector. Different methods were needed because some sample matrices did not have all arsenic species present or were incompatible with particular high-performance liquid chromatography (HPLC) mobile phases. The bias and variability of the methods were evaluated using total arsenic, As(III), As(V), DMA, and MMA results from more than 100 surface-water, groundwater, and acid mine drainage samples, and reference materials. Concentrations in test samples were as much as 13,000??g AsL-1 for As(III) and 3700??g AsL-1 for As(V). Methylated arsenic species were less than 100??g AsL-1 and were found only in certain surface-water samples, and roxarsone was not detected in any of the water samples tested. The distribution of inorganic arsenic species in the test samples ranged from 0% to 90% As(III). Laboratory-speciation method variability for As(III), As(V), MMA, and DMA in reagent water at 0.5??g AsL-1 was 8-13% (n=7). Field-speciation method variability for As(III) and As(V) at 1??g AsL-1 in reagent water was 3-4% (n=3). ?? 2003 Elsevier Ltd. All rights reserved.

  17. Nondestructive Method for Bulk Chemical Characterization of Barred Olivine Chondrules

    Science.gov (United States)

    Montoya-Perez, M. A.; Cervantes-de la Cruz, K. E.; Ruvalcaba-Sil, J. L.

    2017-02-01

    This work develops a bulk chemical characterization of barred olivine chondrules based on the XRF analysis using a portable equipment at the National Research and Conservation Science Laboratory of Cultural Heritage (LANCIC-IF) in Mexico City.

  18. A new cation-exchange method for accurate field speciation of hexavalent chromium

    Science.gov (United States)

    Ball, J.W.; McCleskey, R.B.

    2003-01-01

    A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

  19. Chromium speciation in environmental samples using a solid phase spectrophotometric method

    Science.gov (United States)

    Amin, Alaa S.; Kassem, Mohammed A.

    2012-10-01

    A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H2SO4 and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11 × 107 and 3.90 × 107 L mol-1 cm-1 for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 μg L-1 with RSD of waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested.

  20. Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal [Department of Chemistry, Karadeniz Technical University, Faculty of Arts and Sciences, 61080 Trabzon (Turkey); Soylak, Mustafa [Department of Chemistry, Erciyes University, Faculty of Arts and Sciences, 38039 Kayseri (Turkey)], E-mail: soylak@erciyes.edu.tr

    2009-01-19

    A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H{sub 2}SO{sub 4} and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 {mu}g L{sup -1}. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

  1. Speciation of Dissolved Cadmium

    DEFF Research Database (Denmark)

    Holm, Peter Engelund; Andersen, Sjur; Christensen, Thomas Højlund

    1995-01-01

    Equilibrium dialysis and ion exchange methods, as well as computer calculations (GEOCHEM), were applied for speciation of dissolved cadmium (Cd) in test solutions and leachate samples. The leachate samples originated from soil, compost, landfill waste and industrial waste. The ion exchange (IE...... leachates showed different Cd speciation patterns as expected. Some leachates were dominated by free divalent Cd (1-70%), some by inorganic complexes (1-87%), and some by organic complexes (7-98%)....

  2. Adaptive finite element-element-free Galerkin coupling method for bulk metal forming processes

    Institute of Scientific and Technical Information of China (English)

    Lei-chao LIU; Xiang-huai DONG; Cong-xin LI

    2009-01-01

    An adaptive finite element-element-free Galerkin (FE-EFG) coupling method is proposed and developed for the numerical simulation of bulk metal forming processes. This approach is able to adaptively convert distorted FE elements to EFG domain in analysis. A new scheme to implement adaptive conversion and coupling is presented. The coupling method takes both advantages of finite element method (FEM) and meshless methods. It is capable of handling large deformations with no need of remeshing procedures, while it is computationally more efficient than those full meshless methods. The effectiveness of the proposed method is demonstrated with the numerical simulations of the bulk metal forming processes including forging and extrusion.

  3. Anthropogenic VOC speciation in emission inventories: a method for improvement and evaluation

    Science.gov (United States)

    von Schneidemesser, E.; D'angiola, A.; Granier, C.; Monks, P. S.; Law, K.

    2011-12-01

    Volatile organic compounds (VOCs) are important precursor compounds for the formation of ozone and other secondary organic aerosols. Anthropogenic sources of VOCs are dominated by industrial usage and transportation sources, the latter being extremely important in urban areas. Megacities and large urban conglomerations are emission hot spots that exert disproportionately large adverse health effects on the population and surrounding environment, owing to their high population density and concentrated emission sources. Exceedances of ozone air quality standards are a problem in many urban areas. Improvements in the modelling of ozone precursors would benefit our understanding of the impact of changes in emissions and the effect of future legislation on air quality. As many VOCs are extremely reactive in the atmosphere and have high ozone forming potential, improved speciation of VOCs in models could lead to better predictions of ozone levels and secondary organic aerosol formation. Previously, VOC and carbon monoxide (CO) data from urban areas around the world were compared. Significant differences in VOC concentrations were observed, however, when normalized to CO, the VOC-CO ratios were similar for many locations and over time, even as emission reductions were implemented. The largest variation was found in the lighter alkanes due to the use of alternative transportation fuels in various world regions. These ratios were grouped by region and used to develop a new speciation for surface emissions of VOCs, by applying the regional observed VOC-CO ratios to the CO emissions for the urban areas. Urban areas were defined as 150 inhabitants per km2 or greater. Model simulations were performed using the MOZART-4 chemistry transport model to assess the improved speciation of the VOC emissions. The model outputs were compared to urban observational data where available. The impact of the new speciation of the distribution of CO, OH and ozone at the global scale will be

  4. A multi-method approach for the study of lanthanum speciation in coastal and estuarine sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Babu, P.V.R.; Sarma, V.V.

    et al. 2000) which may not represent natural systems. In order to have a more precise picture on La speciation in sediments, kinetic extraction study was also performed for a better understanding of dynamic and inert La-sediment complexes... in an agate mortar, homogenized and stored at 4 o C until needed. 2.2 Leaching procedure and reagents All the reagents used in this study were of analytical grade or better. All the extraction processes were performed in Teflon containers. 2...

  5. Out of the deep: cryptic speciation in a Neotropical gecko (Squamata, Phyllodactylidae) revealed by species delimitation methods.

    Science.gov (United States)

    Domingos, Fabricius M C B; Bosque, Renan J; Cassimiro, José; Colli, Guarino R; Rodrigues, Miguel T; Santos, Marcella G; Beheregaray, Luciano B

    2014-11-01

    Levels of biodiversity in the Neotropics are largely underestimated despite centuries of research interest in this region. This is particularly true for the Cerrado, the largest Neotropical savanna and a formally recognized biodiversity hotspot. Molecular species delimitation methods have become essential tools to uncover cryptic species and can be notably robust when coupled with morphological information. We present the first evaluation of the monophyly and cryptic speciation of a widespread Cerrado endemic lizard, Gymnodactylus amarali, using phylogenetic and species-trees methods, as well as a coalescent-based Bayesian species delimitation method. We tested whether lineages resulting from the analyses of molecular data are morphologically diagnosed by traditional meristic scale characters. We recovered eight deeply divergent molecular clades within G. amarali, and two additional ones from seasonally dry tropical forest enclaves between the Cerrado and the Caatinga biomes. Analysis of morphological data statistically corroborated the molecular delimitation for all groups, in a pioneering example of the use of support vector machines to investigate morphological differences in animals. The eight G. amarali clades appear monophyletic and endemic to the Cerrado. They display several different properties used by biologists to delineate species and are therefore considered here as candidates for formal taxonomic description. We also present a preliminary account of the biogeographic history of these lineages in the Cerrado, evidence for speciation of sister lineages in the Cerrado-Caatinga contact, and highlight the need for further morphological and genetic studies to assess cryptic diversity in this biodiversity hotspot.

  6. VALIDATED SPECTROPHOTMETRIC METHOD FOR THE DETERMINATION OF SALBUTAMOL SULPHATE IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    Directory of Open Access Journals (Sweden)

    Eswarudu.M.M

    2012-04-01

    Full Text Available A new, simple, accurate and sensitive spectrophotometric method has been developed for the estimation of Salbutamol sulphate in bulk and in pharmaceutical formulations. Salbutamol sulphate shows ʎ max at 292 nm. The drug follows the beer’s lambert’s law in the concentration range of 20-100µ ml. the method was validated by following the analytical performance parameters as suggested by the international conference on harmonization which included accuracy, precision, linearity. All validation parameters were with in the acceptable range. The developed method was successfully applied to estimate the amount of Salbutamol sulphate in bulk and pharmaceutical dosage forms.

  7. METHOD DEVELOPMENT AND VALIDATION OF DULOXETINE HYDROCHLORIDE IN BULK AND FORMULATION USING UV SPECTROPHOTOMETRIC METHOD

    Directory of Open Access Journals (Sweden)

    Kishore Methuku

    2012-06-01

    Full Text Available New, simple and cost effective UV-spectrophotometric method was developed for the estimation of Duloxetine hydrochloride in bulk formulations. Duloxetine hydrochloride was estimated at 290 nm in 20% Acetonitrie. Linearity range was found to be 10–50 μg ml–1 (regression equation: 0.017 + 0.016; r2 = 0.999. The apparent molar absorptivity was found to be 5.922×10-3 mol−1 cm−1 in 20% Acetonitrile. These methods were tested and validated for various parameters according to ICH guidelines and USP. The quantitation limits were found to be 0.2405 μg ml–1 and 0.7289 μg ml–1 in 20% Acetonitrile respectively. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2%, while being simple, cheap and less time consuming and can be suitably applied for the estimation of Duloxetine hydrochloride in different dosage forms and dissolution studies.

  8. Speciation Analysis of Radionuclides in the Environment - NSK-B SPECIATION project report 2009

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Aldahan, Ala; Possnert, Göran;

    The second stage of the NKS-B project SPECIATION was complemented in 2008-2009, which mainly focus on three aspects: (1) Further improvement and development of methods for speciation analysis of radionuclides; (2) Investigation of speciation of some radionuclides in the environment (water......, sediments, particles); and (3) Intercomparison excise for speciation analysis of radionu-clides in soil and sediment. This report summarizes the work completed in the project partners’ laboratories, Method developments include: Development of an rapid and in-suit separation method for the speciation...... analysis of 129I in seawater samples; Development of a simple method for the speciation analysis of 129I in fresh water and seawater samples; Development of an on-line HPLC-ICP-MS method for the direct speciation analysis of 127I in water and leachate samples; Speciation of radionuclides in water includes...

  9. Use of thermal neutron reflection method for chemical analysis of bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Papp, A., E-mail: papppa@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Institute of Experimental Physics, University Debrecen (IEP), 4010 Debrecen-10, Pf. 105 (Hungary)

    2014-09-11

    Microscopic, σ{sub β}, and macroscopic, Σ{sub β}, reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ{sub β} values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ{sub βmol}(z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm{sup 3} dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials.

  10. Use of a modified, high-sensitivity, anodic stripping voltammetry method for determination of zinc speciation in the North Atlantic Ocean.

    Science.gov (United States)

    Jakuba, Rachel Wisniewski; Moffett, James W; Saito, Mak A

    2008-05-05

    Zinc speciation is considered to be an important determinant of the biological availability of zinc. Yet in oceanic surface waters, characterization of zinc speciation is difficult due to the low concentrations of this essential micronutrient. In this study, an anodic stripping voltammetry method previously developed for the total determination of cadmium and lead was successfully adapted to the measurement of zinc speciation. The method differs from previous zinc speciation anodic stripping voltammetry methods in that a fresh mercury film is plated with each sample aliquot. The fresh film anodic stripping voltammetry method was compared to competitive ligand exchange cathodic stripping voltammetry in a profile from the North Atlantic Ocean. Results using the fresh film anodic stripping voltammetry method were similar to those determined using the cathodic stripping voltammetry method, though ligand concentrations determined by fresh film anodic stripping voltammetry were generally slightly higher than those determined by cathodic stripping voltammetry. There did not seem to be a systematic difference between methods for the estimates of conditional stability constants. The ligand concentration in the North Atlantic profile ranged from 0.9 to 1.5 nmol L(-1) as determined by fresh film anodic stripping voltammetry and 0.6 to 1.3 nmol L(-1) as determined by cathodic stripping voltammetry. The conditional stability constants determined by fresh film anodic stripping voltammetry were 10(9.8)-10(10.5) and by cathodic stripping voltammetry were 10(9.8)-10(11.3).

  11. Special Speciation

    Science.gov (United States)

    Countryman, Lyn L.; Maroo, Jill D.

    2015-01-01

    Considerable anecdotal evidence indicates that some of the most difficult concepts that both high school and undergraduate elementary-education students struggle with are those surrounding evolutionary principles, especially speciation. It's no wonder that entry-level biology students are confused, when biologists have multiple definitions of…

  12. Speciation of arsenic by IC-ICP-MS: future standard method and its application on baby food samples

    DEFF Research Database (Denmark)

    Kollander, Barbro; Sloth, Jens Jørgen

    Arsenic is known to most people as extremely poisonous and several criminal authors have used this fact to assassinate their characters in novels for decades. However, the authors seldom or never mention which of the species of arsenic they use, although that is elementary for the outcome...... of the intended murder. For example the organic compound arsenobetaine, the main arsenic species in marine organisms, is regarded as basically harmless to humans while the inorganic forms of arsenic, arsenite and arsenate found in rice, are toxic. To enable the evaluation of the true toxicity from arsenic in food......, some kind of speciation analysis has to be performed. In this work, the concentration of inorganic arsenic in some baby food samples is evaluated. The applied methodology has recently been tested in a collaborative trial as a candidate standardized method for the determination of inorganic arsenic...

  13. DEVELOPMENT AND VALIDATION OF UV METHOD OF TEMOZOLOMIDE IN BULK AND CAPSULE FORMULATION

    Directory of Open Access Journals (Sweden)

    A. Abdul Razak*, Sk. Masthanamma, B. Omshanthi, V. Suresh and P. Obulamma

    2013-04-01

    Full Text Available ABSTRACT: An UV spectrophotometric method for the quantitative determination of Temozolomide (TMZ in bulk and capsule was developed in present work. The parameters linearity, precision, accuracy, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. UV spectroscopic determination was carried out at an absorption maximum of 328 nm using 0.1N Hydrochloric acid as solvent. In the UV spectroscopic method linearity over the concentration range of TMZ was found to be 2-18 µg/ml with a correlation coefficient 0.999. The limit of detection and limit of quantification were found to be 0.5271 and 1.6454 mg/ml respectively. Results of the analysis were validated statistically and by recovery studies. The proposed method is simple, rapid, precise, accurate and reliable and can be used for the routine quantitative analysis of TMZ in bulk and pharmaceutical formulation.

  14. Determination of prilocaine HCl in bulk drug and pharmaceutical formulation by GC-NPD method

    Directory of Open Access Journals (Sweden)

    Atila Alptug

    2013-01-01

    Full Text Available The novel analytical method was developed and validated for determination of prilocaine HCl in bulk drug and pharmaceutical formulation by gas chromatography-nitrogen phosphorus detection (GC-NPD. The chromatographic separation was performed using a HP-5MS column. The calibration curve was linear over the concentration range of 40-1000 ng ml-1 with a correlation coefficient of 0.9998. The limits of detection (LOD and quantification (LOQ of method were 10 ng ml-1 and 35 ng ml-1, respectively. The within-day and between-day precision, expressed as the percent relative standard deviation (RSD% was less than 5.0%, and accuracy (percent relative error was better than 4.0%. The developed method can be directly and easily applied for determination of prilocaine HCl in bulk drug and pharmaceutical formulation using internal standard methodology.

  15. UV-SPECTROPHOTOMETRIC METHOD FOR ESTIMATION OF SECNIDAZOLE IN BULK AND TABLET DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Jinendra M. Sonpetkar et al.

    2012-02-01

    Full Text Available A simple, precise and accurate UV-Spectrophotometric method has been developed and validated for estimation of secnidazole in bulk and tablet dosage form. It shows maximum absorbance at 313 nm with methanol and water (30:70. Estimation was carried out by A(1%1cm and by comparison with standard. Calibration graph was found to be linear (r2 =0.09998 over concentration range of 1-4µg/ml. The proposed methods appear to be simple, sensitive, and reproducible when checked for parameters like accuracy, precision, limit of detection for routine determination of secnidazole in bulk as well as in tablet. The methods can be adopted in its routine analysis.

  16. A new method for the measurement of meteorite bulk volume via ideal gas pycnometry

    Science.gov (United States)

    Li, Shijie; Wang, Shijie; Li, Xiongyao; Li, Yang; Liu, Shen; Coulson, Ian M.

    2012-10-01

    To date, of the many techniques used to measure the bulk volume of meteorites, only three methods (Archimedean bead method, 3-D laser imaging and X-ray microtomography) can be considered as nondestructive or noncontaminating. The bead method can show large, random errors for sample sizes of smaller than 5 cm3. In contrast, 3-D laser imaging is a high-accuracy method even when measuring the bulk volumes of small meteorites. This method is both costly and time consuming, however, and meteorites of a certain shape may lead to some uncertainties in the analysis. The method of X-ray microtomography suffers from the same problems as 3-D laser imaging. This study outlines a new method of high-accuracy, nondestructive and noncontaminating measurement of the bulk volume of meteorite samples. In order to measure the bulk volume of a meteorite, one must measure the total volume of the balloon vacuum packaged meteorite and the volume of balloon that had been used to enclose the meteorite using ideal gas pycnometry. The difference between the two determined volumes is the bulk volume of the meteorite. Through the measurement of zero porosity metal spheres and tempered glass fragments, our results indicate that for a sample which has a volume of between 0.5 and 2 cm3, the relative error of the measurement is less than ±0.6%. Furthermore, this error will be even smaller (less than ±0.1%) if the determined sample size is larger than 2 cm3. The precision of this method shows some volume dependence. For samples smaller than 1 cm3, the standard deviations are less than ±0.328%, and these values will fall to less than ±0.052% for samples larger than 2 cm3. The porosities of nine fragments of Jilin, GaoGuenie, Zaoyang and Zhaodong meteorites have been measured using our vacuum packaging-pycnometry method, with determined average porosities of Jilin, GaoGuenie, Zaoyang and Zhaodong of 9.0307%, 2.9277%, 17.5437% and 5.9748%, respectively. These values agree well with the porosities

  17. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; arsenic speciation in natural-water samples using laboratory and field methods

    Science.gov (United States)

    Garbarino, John R.; Bednar, Anthony J.; Burkhardt, Mark R.

    2002-01-01

    Analytical methods for the determination of arsenite [As(III)], arsenate [As(V)], dimethylarsinate (DMA), monomethylarsonate (MMA), and roxarsone in filtered natural-water samples are described. Various analytical methods can be used for the determination, depending on the arsenic species being determined. Arsenic concentration is determined by using inductively coupled plasma-mass spectrometry (ICP-MS) as an arsenic-specific detector for all methods. Laboratory-speciation methods are described that use an ion chromatographic column to separate the arsenic species; the column length, column packing, and mobile phase are dependent on the species of interest. Regardless of the separation technique, the arsenic species are introduced into plasma by eithe rpneumatic nebulization or arsine generation. Analysis times range from 2 to 8 minutes and method detection limits range from 0.1 to 0.6 microgram-arsenic per liter (ug-As/L), 10 to 60 picograms absolute (for a 100-microliter injection), depending on the arsenic species determined and the analytical method used. A field-generation specciation method also is described that uses a strong anion exchange cartridge to separate As(III) from As(V) in the field. As(III) in the eluate and the As(V) in the cartridge extract are determined by direct nebulization ICP-MS. Methylated arsenic species that also are retained on the cartridge will positively bias As(V) results without further laboratory separations. The method detection limit for field speciation is 0.3 ug-As/L. The distribution of arsenic species must be preserved in the field to eliminate changes caused by photochemical oxidation or metal oxyhydroxide precipitation. Preservation techniques, such as refrigeration, the addition of acides, or the additoin of ethylene-diaminetetraacetic acid (EDTA) and the effects of ambient light were tested. Of the preservatives evaluated, EDTA was found to work best with the laboratory- and field-speciation methods for all sample

  18. Development and Validation of HPTLC Method for the Estimation of Rizatriptan Benzoate in Bulk and Tablets.

    Science.gov (United States)

    Sundar, B Syama; Suneetha, A

    2010-11-01

    A new, simple high performance thin layer chromatographic method has been proposed for the determination of rizatriptan benzoate in a tablet dosage form. The drug was separated on aluminum plates precoated with silica gel 60 F(254) with dichloromethane-acetone-acetic acid 3:2:0.2(v/v/v) as mobilephase. Quantitative analysis was performed by densitometric scanning at 230 nm. The method was validated for linearity, accuracy, precision and robustness. The calibration plot was linear over the range 200-700 ng/band for rizatriptan benzoate. The method was successfully applied to the analysis of drug in bulk and marketed tablets.

  19. Gamma-ray attenuation method as an efficient tool to investigate soil bulk density spatial variability

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F., E-mail: lfpires@uepg.b [Laboratory of Soil Physics and Environmental Sciences, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Rosa, J.A. [Laboratory of Soil Physics, Agricultural Research Institute of Parana, IAPAR, C.E.P. 84.001-970 Ponta Grossa, PR (Brazil); Pereira, A.B. [Laboratory of Agrometeorology, State University of Ponta Grossa, UEPG, C.E.P. 84.030-900 Ponta Grossa, PR (Brazil); Arthur, R.C.J.; Bacchi, O.O.S. [Laboratory of Soil Physics, Center for Nuclear Energy in Agriculture, USP/CENA, C.E.P. 13.400-970 Piracicaba, SP (Brazil)

    2009-11-15

    The spatial variability of soil bulk density (rho{sub b}) was measured by using the volumetric ring method (VRM) and the gamma-ray attenuation method (GAM). Collimated radiation from 3.7 GBq of {sup 241}Am was used to evaluate the soil mass attenuation coefficient and its bulk density. Circular lead collimators were adjusted and aligned between source (D = 1, 2 and 3 mm) and detector (D = 4.5 mm). Results of GAM for average rho{sub b} provided good agreement with the corresponding values obtained gravimetrically. Variations in bulk density for different collimator dimensions can be attributed to multiple scattering after photons interaction with soil, mainly for 3 mm collimator size. The best result of rho{sub b} by the nuclear technique was obtained when rho{sub b} represents an average of the measurements for collimators of 1 and 2 mm. Another cause for the differences in rho{sub b} by GAM and VRM is the heterogeneity of soil when the collimated beam can interact with stones or large air-filled holes or channels present in the sample. Therefore, the pattern of spatial variability obtained by VRM was confirmed by GAM for all collimator sizes. This result is a good indication that GAM can be used with success to analyze soil spatial variability.

  20. Estimation of mercury speciation in soil standard reference materials with different extraction methods by ion chromatography coupled with ICP-MS.

    Science.gov (United States)

    Park, Misun; Yoon, Hyeon; Yoon, Cheolho; Yu, Jae-Young

    2011-01-01

    Analytical methods for the speciation of mercury, based on microwave extraction and sonication extraction, have been tested to determine the inorganic mercury and methyl mercury contents in two standard soil reference materials: SRM 2710 Montana Soil and BCR 580 estuarine sediment. Prior to applying the speciation extraction methods, the mineral compositions were analyzed via XRD analysis, with SRM 2710 shown to be composed mostly of aluminum silicate minerals, while carbonate minerals were the major constituent in BCR 580. Two extraction methods, microwave and sonication, were tested for the analysis and recovery efficiency of total mercury. The accuracy and efficiency of each extraction method was also compared. In the analysis of total mercury, the microwave extraction method, with using methanol and HCl as extractants, was better for SRM2710, while the application of the sonication extraction method was more efficient for the calcite-based BCR 580. The results showed good separation and recovery efficiencies, with values reaching 100% of those estimated. The sonication method was selected for the speciation of mercury, especially in BCR 580. An extraction solution comprising of a 1:1 mixture of methanol and HCl was used for the sonication extraction of BCR 580, with the resulting extractants analyzed by IC-HG-ICP-MS for methyl mercury and inorganic mercury. As a simple, rapid, sensitive, and accurate method, sonication extraction was found to be satisfactory.

  1. Development of an analytical method for antimony speciation in vegetables by HPLC-hydride generation-atomic fluorescence spectrometry.

    Science.gov (United States)

    Olivares, David; Bravo, Manuel; Feldmann, Jorg; Raab, Andrea; Neaman, Alexander; Quiroz, Waldo

    2012-01-01

    A new method for antimony speciation in terrestrial edible vegetables (spinach, onions, and carrots) was developed using HPLC with hydride generation-atomic fluorescence spectrometry. Mechanical agitation and ultrasound were tested as extraction techniques. Different extraction reagents were evaluated and optimal conditions were determined using experimental design methodology, where EDTA (10 mmol/L, pH 2.5) was selected because this chelate solution produced the highest extraction yield and exhibited the best compatibility with the mobile phase. The results demonstrated that EDTA prevents oxidation of Sb(III) to Sb(V) and maintains the stability of antimony species during the entire analytical process. The LOD and precision (RSD values obtained) for Sb(V), Sb(III), and trimethyl Sb(V) were 0.08, 0.07, and 0.9 microg/L and 5.0, 5.2, and 4.7%, respectively, for a 100 microL sample volume. The application of this method to real samples allowed extraction of 50% of total antimony content from spinach, while antimony extracted from carrots and onion samples ranged between 50 and 60 and 54 and 70%, respectively. Only Sb(V) was detected in three roots (onion and spinach) that represented 60-70% of the total antimony in the extracts.

  2. Including the spatial variability of metal speciation in the effect factor in life cycle impact assessment: Limits of the equilibrium partitioning method.

    Science.gov (United States)

    Tromson, Clara; Bulle, Cécile; Deschênes, Louise

    2017-03-01

    In life cycle assessment (LCA), the potential terrestrial ecotoxicity effect of metals, calculated as the effect factor (EF), is usually extrapolated from aquatic ecotoxicological data using the equilibrium partitioning method (EqP) as it is more readily available than terrestrial data. However, when following the AMI recommendations (i.e. with at least enough species that represents three different phyla), there are not enough terrestrial data for which soil properties or metal speciation during ecotoxicological testing are specified to account for the influence of soil property variations on metal speciation when using this approach. Alternatively, the TBLM (Terrestrial Biotic Ligand Model) has been used to determine an EF that accounts for speciation, but is not available for metals; hence it cannot be consistently applied to metals in an LCA context. This paper proposes an approach to include metal speciation by regionalizing the EqP method for Cu, Ni and Zn with a geochemical speciation model (the Windermere Humic Aqueous Model 7.0), for 5213 soils selected from the Harmonized World Soil Database. Results obtained by this approach (EF(EqP)regionalized) are compared to the EFs calculated with the conventional EqP method, to the EFs based on available terrestrial data and to the EFs calculated with the TBLM (EF(TBLM)regionalized) when available. The spatial variability contribution of the EF to the overall spatial variability of the characterization factor (CF) has been analyzed. It was found that the EFs(EqP)regionalized show a significant spatial variability. The EFs calculated with the two non-regionalized methods (EqP and terrestrial data) fall within the range of the EFs(EqP)regionalized. The EFs(TBLM)regionalized cover a larger range of values than the EFs(EqP)regionalized but the two methods are not correlated. This paper highlights the importance of including speciation into the terrestrial EF and shows that using the regionalized EqP approach is not an

  3. Estimating the duration of speciation from phylogenies.

    Science.gov (United States)

    Etienne, Rampal S; Morlon, Hélène; Lambert, Amaury

    2014-08-01

    Speciation is not instantaneous but takes time. The protracted birth-death diversification model incorporates this fact and predicts the often observed slowdown of lineage accumulation toward the present. The mathematical complexity of the protracted speciation model has barred estimation of its parameters until recently a method to compute the likelihood of phylogenetic branching times under this model was outlined (Lambert et al. ). Here, we implement this method and study using simulated phylogenies of extant species how well we can estimate the model parameters (rate of initiation of speciation, rate of extinction of incipient and good species, and rate of completion of speciation) as well as the duration of speciation, which is a combination of the aforementioned parameters. We illustrate our approach by applying it to a primate phylogeny. The simulations show that phylogenies often do not contain enough information to provide unbiased estimates of the speciation-initiation rate and the extinction rate, but the duration of speciation can be estimated without much bias. The estimate of the duration of speciation for the primate clade is consistent with literature estimates. We conclude that phylogenies combined with the protracted speciation model provide a promising way to estimate the duration of speciation.

  4. Bulk Electrical Cable Non-Destructive Examination Methods for Nuclear Power Plant Cable Aging Management Programs

    Energy Technology Data Exchange (ETDEWEB)

    Glass, Samuel W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jones, Anthony M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fifield, Leonard S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hartman, Trenton S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-01

    This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of nondestructive test methods focusing particularly on bulk electrical test methods that provide key indicators of cable aging and damage. The work includes a review of relevant literature as well as hands-on experimental verification of inspection capabilities. As nuclear power plants consider applying for second, or subsequent, license renewal to extend their operating period from 60 years to 80 years, it is important to understand how the materials installed in plant systems and components will age during that time and develop aging management programs to assure continued safe operation under normal and design basis events (DBE). Normal component and system tests typically confirm the cables can perform their normal operational function. The focus of the cable test program, however, is directed toward the more demanding challenge of assuring the cable function under accident or DBE. The industry has adopted 50% elongation at break (EAB) relative to the un-aged cable condition as the acceptability standard. All tests are benchmarked against the cable EAB test. EAB, however, is a destructive test so the test programs must apply an array of other nondestructive examination (NDE) tests to assure or infer the overall set of cable’s system integrity. Assessment of cable integrity is further complicated in many cases by vendor’s use of dissimilar material for jacket and insulation. Frequently the jacket will degrade more rapidly than the underlying insulation. Although this can serve as an early alert to cable damage, direct test of the cable insulation without violating the protective jacket becomes problematic. This report addresses the range of bulk electrical NDE cable tests that are or could be practically implemented in a field-test situation with a particular focus on frequency domain reflectometry (FDR). The FDR test method offers numerous advantages

  5. Method for determining transport critical current densities and flux penetration depth in bulk superconductors

    Science.gov (United States)

    Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

    1992-01-01

    A contact-less method for determining transport critical current density and flux penetration depth in bulk superconductor material. A compressor having a hollow interior and a plunger for selectively reducing the free space area for distribution of the magnetic flux therein are formed of superconductor material. Analytical relationships, based upon the critical state model, Maxwell's equations and geometrical relationships define transport critical current density and flux penetration depth in terms of the initial trapped magnetic flux density and the ratio between initial and final magnetic flux densities whereby data may be reliably determined by means of the simple test apparatus for evaluating the current density and flux penetration depth.

  6. HPLC METHOD DEVELOPMENT OF AMLODIPINE BY RP-HPLC IN ITS BULK DOSAGE FORMS

    Directory of Open Access Journals (Sweden)

    V. Naveen Kumar, K. Kiran kumar, P. Ramesh Babu, K. Anilkumar

    2012-06-01

    Full Text Available A new, simple, precise, sensitive, accurate and reproducible Reverse phase HPLC method was developed and validated for the analysis of amlodipine in bulk dosage forms. The separation was conducted by using c-18 RP-HPLC coloumn, which was maintained at ambient temperature. The mobile phase consisting of Phosphate buffer and Acetonitrile (90:10v/v was delivered at a rate of 1.5 ml/min. The analysis was detected by using UV detector at the wave length of 225nm.The method is validated for its specificity, precision, accuracy, linearity and robustness. The method was found to be linear over the concentration range 10-100 g/ml (r2 =0.999. The retention time for amlodipine was found to be 3.34min. Limit of quantification of the method is 0.179g/ml and limit of detection is 0.054 g/ml.

  7. Speciative determination of total V and dissolved inorganic vanadium species in environmental waters by catalytic–kinetic spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Ramazan Gürkan

    2017-02-01

    Full Text Available A kinetic determination of V(V as a catalyst was spectrophotometrically performed by using the indicator reaction of Gallamine blue (GB+ and bromate at pH 2.0. The reaction was followed by measuring absorbance change for a fixed-time of 3 min at 537 nm. The variables such as reagent concentration, pH, buffer concentration, ionic strength and temperature were optimized to improve the selectivity and sensitivity. Under the optimized conditions, the determination of V(V was performed in the range 1–100 μg L−1 with limits of detection and quantification of 0.31 and 0.94 μg L−1. The developed kinetic method is sufficiently sensitive, selective and simple. It was successfully applied to the speciative determination of total V and inorganic dissolved vanadium species, V(V and V(IV in environmental water samples. The oxidizing property of permanganate is used to differentiate between V(IV and V(V species. The V(IV content was found by subtracting the V(V content from those of total V. The recovery is above 95% for V(V spiked samples. Additionally, the accuracy was validated by analysis of a certified water sample, CRM TMDA-53.3, and the results were in good agreement with the certified value.

  8. Alternative method to determine the bulk etch rate of Lr-115 detectors

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, D.; Sajo B, L.; Barros, H.; Greaves, E. D. [Universidad Simon Bolivar, Laboratorio de Fisica Nuclear, Apdo. Postal 89000, Caracas (Venezuela, Bolivarian Republic of); Palacios, F. [Universidad de Oriente, Santiago de Cuba (Cuba)

    2010-02-15

    The measurements using the Lr-115 solid-state nuclear track detector depend critically on the removed thickness of the active layer during etching. In this work, Lr-115 detectors exposed to alpha particles were etched under no stirring in a 2.5 N NaOH solution at a temperature of 60{+-}1 C and different etching times (from 0.5 to 2.5 hours). The thickness of the removed layer was determined by a variant of the gravimetric method, so that the bulk etch rate could be deduced from mass change measurements of detectors. The bulk etch rate was found to be 3.63 {+-} 0.09 {mu}m.h{sup -}1, which agrees with most of the reported values. Comparisons of our results with the obtained by the optical density method are in correspondence. We propose here a fast, simple, and nondestructive method to determine the active-layer thickness of the Lr-115 solid-state nuclear track detector with good accuracy for routine measurements. (Author)

  9. Defence Research and Development Canada: Suffield research on nuclear methods for detection of buried bulk explosives

    Science.gov (United States)

    McFee, John E.; Faust, Anthony A.

    2011-06-01

    Defence R&D Canada - Suffield has conducted research and development on nuclear methods for detection of bulk explosives since 1994. Initial efforts were directed at confirmation of the presence of bulk explosives in land mines and improvised explosive devices (IEDs). In close collaboration with a few key Canadian companies, methods suitable for vehicle-mounted or fixed position applications and those suitable for person- or small robotportable roles have been studied. Vehicle-mounted systems mainly employ detection of characteristic radiation, whereas person-portable systems use imaging of back scattered radiation intensity distributions. Two key design tenets have been reduction of personnel shielding by the use of teleoperation and custom design of sensors to address the particular problem, rather than adapting an existing sensor to a problem. This is shown in a number of recent research examples. Among vehicle-mounted systems, recent research to improve the thermal neutron analysis (TNA) sensors, which were put into service with the Canadian Forces in 2002, are discussed. Research on fast neutron analysis (FNA) and associated particle imaging (API), which can augment or replace TNA, depending on the application, are described. Monoenergetic gamma ray induced photoneutron spectroscopy is a novel method which has a number of potential advantages and disadvantages over TNA and FNA. Sources, detectors and geometries have been identified and modelling studies have suggested feasibility. Among person-portable systems, research on neutron backscatter imaging and X-ray coded aperture backscatter imaging are discussed.

  10. A validated stability-indicating HPLC method for determination of varenicline in its bulk and tablets

    Directory of Open Access Journals (Sweden)

    Kassem Mohamed G

    2011-06-01

    Full Text Available Abstract A simple, sensitive and accurate stability-indicating HPLC method has been developed and validated for determination of varenicline (VRC in its bulk form and pharmaceutical tablets. Chromatographic separation was achieved on a Zorbax Eclipse XDB-C8 column (150 mm × 4.6 mm i.d., particle size 5 μm, maintained at ambient temperature by a mobile phase consisted of acetonitrile and 50 mM potassium dihydrogen phosphate buffer (10:90, v/v with apparent pH of 3.5 ± 0.1 and a flow rate of 1.0 ml/min. The detection wavelength was set at 235 nm. VRC was subjected to different accelerated stress conditions. The degradation products, when any, were well resolved from the pure drug with significantly different retention time values. The method was linear (r = 0.9998 at a concentration range of 2 - 14 μg/ml. The limit of detection and limit of quantitation were 0.38 and 1.11 μg/ml, respectively. The intra- and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 2%. The accuracy of the method was proved; the mean recovery of VRC was 100.10 ± 1.08%. The proposed method has high throughput as the analysis involved short run-time (~ 6 min. The method met the ICH/FDA regulatory requirements. The proposed method was successfully applied for the determination of VRC in bulk and tablets with acceptable accuracy and precisions; the label claim percentages were 99.65 ± 0.32%. The results demonstrated that the method would have a great value when applied in quality control and stability studies for VRC.

  11. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  12. Research progress in detection methods of arsenic and arsenic speciation%砷及砷的形态检测方法的研究现状

    Institute of Scientific and Technical Information of China (English)

    张金玲; 钟耀广; 孙晓红; 邓健康; 林栋

    2012-01-01

    砷是一种广泛分布于自然界的微量元素,摄入过量砷元素容易引起砷的急性中毒而致死,应引起人们足够的重视。砷的毒性主要取决于它的化学形态,形态不同毒性差异很大,所以选择适当、简便、快速的测定方法是现代分析技术取得发展的必要条件。本文综述了近年来砷及其形态常用的测定方法,并且分析了各检测方法的优缺点,展望了砷及其形态检测技术的发展前景。%Arsenic,a kind of trace elements, is widely distributed in nature. Excessive arsenic intake can lead to acute poisoning and even to death, which should arouse the society' s enough attention and awareness. The toxicity of arsenic compounds is mainly determined by its chemical speciation, and the toxicity of arsenic in different speciation varies greatly.It is essential for the development of modern analytical techniques that selecting the appropriate,simple and rapid determination method.Some common methods for the determination of arsenic and its speciation were reviewed and the advantages and disadvantages of various detection methods were analyzed.The article prospected the research on detection technique of arsenic and its speciation.

  13. ANALYTICAL METHOD DEVELOPMENT AND VALIDATION OF METAXALONE IN BULK AND ITS PHARMACEUTICAL FORMULATION BY UV SPECTROSCOPIC METHOD

    Directory of Open Access Journals (Sweden)

    N. V. Mahipal Reddy

    2013-03-01

    Full Text Available Metaxalone, a muscle relaxant used to relax muscles and relieve pain caused by strains, sprains and othermusculoskeletal conditions. A simple, accurate, precise, reproducible, highly sensitive, economic UV spectrophotometric method has been developed for the estimation of metaxalon in bulk and tablet dosage form. In this method metaxalon showed maximum absorbance at 280 nm in methanol. The developed spectrophotometric method was validated in accordance with ICH guidelines. Linearity of the method was found to be 5 - 160µg/ml. The method obeyed Beer’s law in the concentration range of 5 -160 µg/ml. The LOD and LOQ were found to be 3.489μg/ml and 10.575μg/ml respectively. A mean recovery of metaxalon in tablet dosage form was found to be 99.69%.the method was found to be simple, accurate, precise, specific, sensitive, reproducible and can be directly and easily applied to tablet dosage form.

  14. A Newly Improved Modified Method Development and Validation of Bromofenac Sodium Sesquihydrate in Bulk Drug Manufacturing

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Yelamanchi V

    2016-10-01

    Full Text Available The main objective of this study was to develop a simple, efficient, specific, precise and accurate newly improved modified Reverse Phase High Performance Liquid Chromatographic Purity (or Related substance method for bromofenac sodium sesquihydrate active pharmaceuticals ingredient dosage form. Validation of analytical method is the confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled as per ICH, USP, BP or any other suitable regulatory guidelines. The Reverse Phase High Performance Liquid Chromatographic Gradient method was developed by utilizing Waters Symmetry C8, 150x4.6mm, 3.5µm on Waters 2487 series Liquid Chromatograph. The retention time of bromofenac sodium sesquihydrate was found to be 5.973minutes. Considering all the results of validation parameters simplicity of the method and the cost effectiveness of the overall procedure, it is possible to conclude that the developed method can be suitable for the regular quality control determination of bromofenac sodium sesquihydrate in bulk as well as pharmaceutical dosage form.The developed Reverse Phase High Performance Liquid Chromatographic Purity (or Related substance method for bromofenac sodium sesquihydrate active pharmaceuticals ingredient method was validated with respect to System Suitability , linearity, , precision ,Range, Ruggedness, Test Solution and Mobile phase stability ,Robustness..

  15. Mercury speciation analysis in seafood by species-specific isotope dilution: method validation and occurrence data

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, Stephanie; Guerin, Thierry [Agence Nationale de Securite Sanitaire de l' Alimentation, Laboratoire de Securite des Aliments de Maisons-Alfort, Unite des Contaminants Inorganiques et Mineraux de l' Environnement, ANSES, Maisons-Alfort (France); Monperrus, Mathilde; Donard, Olivier F.X.; Amouroux, David [IPREM UMR 5254 CNRS - Universite de Pau et des Pays de l' Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut des Sciences Analytiques et de Physico-chimie pour l' Environnement et les Materiaux, Pau Cedex (France)

    2011-11-15

    Methylmercury (MeHg) and total mercury (THg) in seafood were determined using species-specific isotope dilution analysis and gas chromatography combined with inductively coupled plasma mass spectrometry. Sample preparation methods (extraction and derivation step) were evaluated on certified reference materials using isotopically enriched Hg species. Solid-liquid extraction, derivation by propylation and automated agitation gave excellent accuracy and precision results. Satisfactory figures of merit for the selected method were obtained in terms of limit of quantification (1.2 {mu}g Hg kg{sup -1} for MeHg and 1.4 {mu}g Hg kg{sup -1} for THg), repeatability (1.3-1.7%), intermediate precision reproducibility (1.5% for MeHg and 2.2% for THg) and trueness (bias error less than 7%). By means of a recent strategy based on accuracy profiles ({beta}-expectation tolerance intervals), the selected method was successfully validated in the range of approximately 0.15-5.1 mg kg{sup -1} for MeHg and 0.27-5.2 mg kg{sup -1} for THg. Probability {beta} was set to 95% and the acceptability limits to {+-}15%. The method was then applied to 62 seafood samples representative of consumption in the French population. The MeHg concentrations were generally low (1.9-588 {mu}g kg{sup -1}), and the percentage of MeHg varied from 28% to 98% in shellfish and from 84% to 97% in fish. For all real samples tested, methylation and demethylation reactions were not significant, except in one oyster sample. The method presented here could be used for monitoring food contamination by MeHg and inorganic Hg in the future to more accurately assess human exposure. (orig.)

  16. Bulk Electrical Cable Non-Destructive Examination Methods for Nuclear Power Plant Cable Aging Management Programs

    Energy Technology Data Exchange (ETDEWEB)

    Glass, Samuel W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jones, Anthony M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fifield, Leonard S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hartman, Trenton S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-01

    This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of nondestructive test methods focusing particularly on bulk electrical test methods that provide key indicators of cable aging and damage. The work includes a review of relevant literature as well as hands-on experimental verification of inspection capabilities. As nuclear power plants consider applying for second, or subsequent, license renewal to extend their operating period from 60 years to 80 years, it is important to understand how the materials installed in plant systems and components will age during that time and develop aging management programs to assure continued safe operation under normal and design basis events (DBE). Normal component and system tests typically confirm the cables can perform their normal operational function. The focus of the cable test program, however, is directed toward the more demanding challenge of assuring the cable function under accident or DBE. The industry has adopted 50% elongation at break (EAB) relative to the un-aged cable condition as the acceptability standard. All tests are benchmarked against the cable EAB test. EAB, however, is a destructive test so the test programs must apply an array of other nondestructive examination (NDE) tests to assure or infer the overall set of cable’s system integrity. Assessment of cable integrity is further complicated in many cases by vendor’s use of dissimilar material for jacket and insulation. Frequently the jacket will degrade more rapidly than the underlying insulation. Although this can serve as an early alert to cable damage, direct test of the cable insulation without violating the protective jacket becomes problematic. This report addresses the range of bulk electrical NDE cable tests that are or could be practically implemented in a field-test situation with a particular focus on frequency domain reflectometry (FDR). The FDR test method offers numerous advantages

  17. RP-HPLC Method Development and Validation of Abacavir Sulphate in Bulk and Tablet Dosage Form

    Directory of Open Access Journals (Sweden)

    S. LAVANYA

    2014-11-01

    Full Text Available RP-HPLC method was developed for the estimation of abacavir sulphate in bulk and pharmaceutical dosage form (tablets by using INERTSIL ODS 3V column, C18 (250x4.6 ID mobile phase consisting of a mixture of 10mM phosphate buffer: ACN (60:40 v/v % PH: 4.0 with detection of 287 nm. The retention time was found to be 2.430min and linearity was observed in the range 60-140μg /ml. Still now there were a number of analytical methods were developed for the estimation of abacavir in pharmaceutical dosage form and also in biological samples like spectroscopic methods, chromatographic methods, etc. But the present method was met the validation parameters according ICH guidelines like accuracy, precision, linearity, range, robustness, ruggedness, limit of detection and limit of quantitation, etc. with a short around time. The method was found to be precise as indicated by the repeatability analysis, showing %RSD less than 2.

  18. Kinetic speciation of mercury–humate complexes in aqueous solutions by using competing ligand exchange method

    Digital Repository Service at National Institute of Oceanography (India)

    Vudamala, K.; Chakraborty, P.

    . Materials and methods 2.1 Chemicals and materials A stock solution (1,000 mg dm-3, NIST Hg (NO3)2 in 10 % HNO3 CertiPUR) of Hg was purchased from Merck Chemicals, Germany. Standard solutions of Hg were prepared daily by dilution of the stock solution... in model solutions containing HA and varying concentration of Hg. The solutions were equilibrated for 24 hrs. Teflon reactor of 400 ml (containing Hg and HA solution) was continually stirred with a Teflon coated magnetic stirring bar throughout...

  19. Bulk Al/SiC nanocomposite prepared by ball milling and hot pressing method

    Institute of Scientific and Technical Information of China (English)

    GU Wan-li

    2006-01-01

    Nano-sized Al/SiC powders were prepared by mechanical alloying method. Two sorts of SiC particle,i.e.,nano-sized and popular micron-sized SiC were utilized. The particle size and microstructure of the milled powder were characterised. Effects of the particle size and agglomerate state of SiC,as well as the microstructure of Al/SiC nanocomposite were studied by SEM and TEM. The results show that nano-sized SiC particles is dispersed in aluminium uniformly after ball milled for only 2 h,whereas the similar process need about 10 h for popular micron-sized SiC particle. The bulk Al/SiC nanocomposite can be fabricated by hot pressing the nano-sized Al/SiC powders at temperature about 723 K under pressure of 100 MPa.

  20. Large bulk Y-Ba-Cu-O superconductors fabricated by multiseeding melt growth methods

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    We have fabricated the large single domain YBaCuO bulk superconductors by using multiseeding technique combined with composition gradient in the precursor. Obviously, the growth time can be shortened by multiseeding method and the weak links between grain boundaries originated from different seeds can be also overcome with introducing the chemical component gradient and arranging the seeds exactly. For these YBCO disks, only single peak occurs in the distributions of trapped field, and the magnetic levitation force is equal to that of the same size sample fabricated with single seed. Although the arrangement of seeds is similar, the distribution of trapped field still shows four peaks for the sample without composition gradient.

  1. A validated HPLC stability-indicating method for the determination of diacerhein in bulk drug substance.

    Science.gov (United States)

    Giannellini, Valerio; Salvatore, Francesco; Bartolucci, Gianluca; Coran, Silvia A; Bambagiotti-Alberti, Massimo

    2005-09-15

    A novel stability-indicating high-performance liquid chromatographic (HPLC) method was developed and validated for the assay of diacerhein in bulk forms. Diacerhein was found to degrade in alkaline and acidic conditions and also under oxidative stress. The drug was stable to dry heat and in presence of light. Resolution of drug, its potential impurities and degradation products were achieved on a RP18 (endcapped) column utilizing 0.1 M phosphoric acid and methanol (40:60, v/v) as eluent at the detection wavelength of 254 nm. The validation studies were carried out fulfilling International Conference on Harmonisation (ICH) requirements. The procedure was found to be specific, linear, precise (including intermediate precision), accurate and robust.

  2. Validated LC method for the estimation of voriconazole in bulk and formulation

    Directory of Open Access Journals (Sweden)

    Patel C

    2009-01-01

    Full Text Available Reversed phase high performance liquid chromatographic method was developed and validated for the estimation of voriconazole in bulk and formulation using prominence diode array detector. Selected mobile phase was a combination of water:acetonitrile (35:65 % v/v and wavelength selected was 256 nm. Retention time of voriconazole was 3.95 min. Linearity of the method was found to be 0.1 to 2 µg/ml, with the regression coefficient of 0.999. This method was validated according to ICH guidelines. Quantification was done by calculating area of the peak and the detection limit and quantitation limit ware 0.026 µg/ml and 0.1 µg/ml, respectively. There was no significant difference in the intra day and inter day analysis of voriconazole determined for three different concentrations using this method. Present method can be applied for the determination of voriconazole in quality control of formulation without interference of the excipients.

  3. Elemental Analysis and Comparison of Bulk Soil Using LA-ICP-MS and LIBS methods

    Science.gov (United States)

    Almirall, J.

    2012-04-01

    Elemental analysis methods utilizing Laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS) were developed and used in the characterization of soil samples from the US and Canada as part of a comprehensive forensic evaluation of soils. A LA-ICP-MS method was recently optimized for analysis and comparison between different soil samples in an environmental forensic application [1,2] and LIBS has recently attracted the interest of analytical chemists and forensic laboratories as a simpler, lower cost alternative to the more established analytical methods. In developing a LIBS method, there are many parameters to consider, including laser wavelength, spectral resolution, sensitivity, and matrix effects. The first LIBS method using a 266 nm laser for forensic soil analysis has also been recently reported by our group [3]. The results of an inter-laboratory comparison involving thirteen (13) laboratories conducting bulk elemental analysis by various methods are also reported. The aims of the inter-laboratory tests were: a) to evaluate the inter-laboratory performance of three methods (LA-ICP-MS, µXRF and LIBS) in terms of accuracy (bias), precision (relative standard deviation, RSD) and sensitivity using standard reference materials (SRMs); b) to evaluate the newly released NIST SRM 2710a, which supersedes 2710; and c) to evaluate the utility of LIBS as an alternative technique to LA-ICP-MS and µXRF for bulk analysis of soils. Each sample and standard was homogenized in a high-speed ball mill and pressed into pellets. Participants were instructed to measure the following elements: 7Li, 25Mg, 27Al, 42Ca, 45Sc, 47,49Ti, 51V, 55Mn, 88Sr, 137Ba, 206,207,208 Pb (LA-ICP-MS); Ti, Cr, Mn, Fe, Cu, Sr, Zr, Pb (µXRF); Ba, Cr, Cu, Fe, Li, Mg, Mn, Pb, Sr, Ti, Zr (LIBS). For both LIBS and µXRF, the choice of appropriate spectral lines was determined by the user, optimizing for linearity, sensitivity and precision

  4. Method development, validation and stability study of ritonavir in bulk and pharmaceutical dosage form by spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Anindita Behera

    2011-01-01

    Full Text Available Background: Ritonavir is a protease inhibitor and mostly used as a booster for increasing the bioavailability of other protease inhibitors like Atazanavir Sulfate and Lopinavir. Aims: Quality assessment of the new dosage form of Ritonavir i.e. tablets is very essential, so two sensitive, simple and precise methods are developed for quantification of Ritonavir in bulk and tablet dosage forms. Materials and Methods: The first method is based on first order derivative method and the second is based on area under curve method. Both the methods are validated according to international conference of harmonization (ICH guidelines. A stability study of Ritonavir is done in UV - Visible Spectrophotometer under different stress conditions recommended by ICH guidelines. Results: The absorption maximum is found to be 239nm in methanol. The absorption maximum in first method is chosen at 253.2nm, and the linearity is found between 4 - 20 ΅g/ml with coefficient of correlation value 0.9981. In the second method, the range for area under curve selected is 237 - 242nm. The linearity is found between 4 -20 ΅g/ml with coefficient of correlation value 0.9992. Conclusion: The developed methods are validated and found to be simple, rapid, precise and cost-effective. The degradation study in tablet dosage form can be used as a stability indicating assay method.

  5. Speciation analysis of radionuclides in the environment. NKS-B speciation project report 2007

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolin Hou (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Aldahan, A. (Uppsala Univ., Dept. of Earth Science, Uppsala (Sweden)); Possnert, G. (Uppsala Univ., Tandem Lab., Uppsala (Sweden)); Lujaniene, G. (Institute of Physics, Vilnius (Lithuania)); Lehto, J. (Univ. of Helsinki, Dept. of Chemistry, Helsinki (Finland)); Salbu, B. (Norwegian Univ. of Life Sciences (UMB), AAs (Norway))

    2008-07-15

    This report describes the work carried out under the NUK-B project SPECIATION 2007. In 2007, the project partners had two meeting in April and November, organized a NUK seminar on speciation and hot particles. SPECIATION 2007 t mainly focused on two issues on speciation (1) further development of speciation methods for radionuclides, and (2) investigation of speciation of radionuclides in environment. The report summarized the work done in partners labs, which includes: (1) Further development on the speciation of 129I and 127I in water samples; (2) Speciation method for 129I and 127I in air; (3) Dynamic system for fractionation of Pu and Am in soil and sediment; (4) Investigation on Re-absorption of Pu during the fractionation of Pu in soil and sediment; (5) Speciation of 129I in North Sea surface water; (6) Partition of 137Cs and 129I in the Nordic lake sediment, pore-water and lake water; (7) Sequential extraction of Pu in soil, sediment and concrete samples, (8) Pu sorption to Mn and Fe oxides in the geological materials, (10) Investigation of the adsorbed species of lanthanides and actinides on clays surfaces. In addition, two review articles on the speciation of plutonium and iodine in environmental are planned to be submitted to an international journal for publication. (au)

  6. Development and Validation of HLPC Method for the Estimation of Lamotrigine in Bulk and Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    T. Vijaya Bhaskara Reddy

    2013-01-01

    Full Text Available A simple, precise, accurate, and rapid HPLC method was developed to estimate the amount of lamotrigine in bulk and its pharmaceutical formulations. Waters Alliance HPLC system equipped with autosampler, ultraviolet detector, and Symmetry C8 (4.6 mm ID × 150 mm, 3.5 μm, Make: XTerra column were used for the quantification of the drug. Separation was carried out at a flow rate of 0.7 mL/min. of mobile phase (acetonitrile and potassium dihydrogen phosphate buffer of pH=7.0 in the ratio 60 : 40 v/v, and the detection was carried out at a wavelength of 215 nm. The retention time of lamotrigine was found to be 2.797 min. The linearity was obeyed in the range of concentration 5–25 μg/mL. The developed method was found to be repeatable and reproducible; hence, it can be used as an alternative method in assay of the lamotrigine in any pharmaceutical industries.

  7. Bulk Synthesis and Characterization of Ti3Al Nanoparticles by Flow-Levitation Method

    Directory of Open Access Journals (Sweden)

    Shanjun Chen

    2013-01-01

    Full Text Available A novel bulk synthesis method for preparing high pure Ti3Al nanoparticles was developed by flow-levitation method (FL. The Ti and Al vapours ascending from the high temperature levitated droplet were condensed by cryogenic Ar gas under atmospheric pressure. The morphology, crystalline structure, and chemical composition of Ti3Al nanoparticles were, respectively, investigated by transmission electron microscopy, X-ray diffraction, and inductively coupled plasma atomic emission spectrometry. The results indicated that the Ti3Al powders are nearly spherical-shaped, and the particle size ranges from several nanometers to 100 nm in diameter. Measurements of the d-spacing from X-ray (XRD and electron diffraction studies confirmed that the Ti3Al nanoparticles have a hexagonal structure. A thin oxidation coating of 2-3 nm in thickness was formed around the particles after exposure to air. Based on the XPS measurements, the surface coating of the Ti3Al nanoparticles is a mixture of Al2O3 and TiO2. The production rate of Ti3Al nanoparticles was estimated to be about 3 g/h. This method has a great potential in mass production of Ti3Al nanoparticles.

  8. Speciation in fishes.

    Science.gov (United States)

    Bernardi, Giacomo

    2013-11-01

    The field of speciation has seen much renewed interest in the past few years, with theoretical and empirical advances that have moved it from a descriptive field to a predictive and testable one. The goal of this review is to provide a general background on research on speciation as it pertains to fishes. Three major components to the question are first discussed: the spatial, ecological and sexual factors that influence speciation mechanisms. We then move to the latest developments in the field of speciation genomics. Affordable and rapidly available, massively parallel sequencing data allow speciation studies to converge into a single comprehensive line of investigation, where the focus has shifted to the search for speciation genes and genomic islands of speciation. We argue that fish present a very diverse array of scenarios, making them an ideal model to study speciation processes.

  9. Molecular Dynamics Study of a Thermal Expansion Coefficient: Ti Bulk with an Elastic Minimum Image Method

    Institute of Scientific and Technical Information of China (English)

    Yakup Hundur; Rainer Hippler; Ziya B. Güven(c)

    2006-01-01

    @@ Linear thermal expansion coefficient (TEC) of Ti bulk is investigated by means of molecular dynamics simulation.The elastic minimum image convention of periodic boundary conditions is introduced to allow the bulk to adjust its size according to the new fixed temperature. The TEC and the specific heat of Ti are compared to the available theoretical and experimental data.

  10. Comparison of two experimental speciation methods with a theoretical approach to monitor free and labile Cd fractions in soil solutions.

    Science.gov (United States)

    Parat, C; Cornu, J-Y; Schneider, A; Authier, L; Sapin-Didier, V; Denaix, L; Potin-Gautier, M

    2009-08-26

    This work focused on the suitability of two techniques to monitor cadmium speciation in soil solutions collected during a 7-day incubation of a contaminated soil. Anodic stripping voltammetry (ASV) and ion exchange were performed on soil solutions collected daily and results were compared with calculations obtained with the speciation software Visual MINTEQ. The electrochemically labile Cd fraction was greater than the exchange-estimated free Cd fraction during the first 6 days, after which it decreased sharply during the last 2 days to reach values close to the exchange-estimated free Cd fraction. Further investigations showed that the increase in pH was mainly responsible for the reduction. However, calculations performed with Visual MINTEQ software clearly demonstrated that a change in the nature of organic matter and/or its complexing capacity also needed to be taken into consideration.

  11. Comparison of two experimental speciation methods with a theoretical approach to monitor free and labile Cd fractions in soil solutions

    Energy Technology Data Exchange (ETDEWEB)

    Parat, C., E-mail: corinne.parat@univ-pau.fr [IPREM, UMR 5254, E.C.A.B.I.E., Avenue P. Angot, 64053 Pau Cedex 9 (France); Cornu, J.-Y.; Schneider, A. [INRA, UMR 1220, T.C.E.M., BP 81, 33883 Villenave d' Ornon (France); Authier, L. [IPREM, UMR 5254, E.C.A.B.I.E., Avenue P. Angot, 64053 Pau Cedex 9 (France); Sapin-Didier, V.; Denaix, L. [INRA, UMR 1220, T.C.E.M., BP 81, 33883 Villenave d' Ornon (France); Potin-Gautier, M. [IPREM, UMR 5254, E.C.A.B.I.E., Avenue P. Angot, 64053 Pau Cedex 9 (France)

    2009-08-26

    This work focused on the suitability of two techniques to monitor cadmium speciation in soil solutions collected during a 7-day incubation of a contaminated soil. Anodic stripping voltammetry (ASV) and ion exchange were performed on soil solutions collected daily and results were compared with calculations obtained with the speciation software Visual MINTEQ. The electrochemically labile Cd fraction was greater than the exchange-estimated free Cd fraction during the first 6 days, after which it decreased sharply during the last 2 days to reach values close to the exchange-estimated free Cd fraction. Further investigations showed that the increase in pH was mainly responsible for the reduction. However, calculations performed with Visual MINTEQ software clearly demonstrated that a change in the nature of organic matter and/or its complexing capacity also needed to be taken into consideration.

  12. Speciation analysis of radionuclides in the environment - NSK-B SPECIATION project report 2009

    Energy Technology Data Exchange (ETDEWEB)

    Hou, X. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Aldahan, A. (Uppsala Univ., Dept. of Earth Science (Sweden)); Possnert, G. (Uppsala Univ., Tandem Lab. (Sweden)); Lujaniene, G. (Univ. of Helsinki, Lab. of Radiochemistry (Finland)); Lehto, J. (Institute of Physics (Lithuania)); Skipperud, L.; Lind, O.C.; Salbu, B. (Norwegian Univ. of Life Sciences, Isotope Lab., AAs (Norway))

    2009-10-15

    The second stage of the NKS-B project SPECIATION was complemented in 2008-2009, which mainly focus on three aspects: (1) Further improvement and development of methods for speciation analysis of radionuclides; (2) Investigation of speciation of some radionuclides in the environment (water, sediments, particles); and (3) Intercomparison excise for speciation analysis of radionuclides in soil and sediment. This report summarizes the work completed in the project partners' laboratories. Method developments include: Development of an rapid and in-suit separation method for the speciation analysis of 129I in seawater samples; Development of a simple method for the speciation analysis of 129I in fresh water and seawater samples; Development of an on-line HPLC-ICP-MS method for the direct speciation analysis of 127I in water and leachate samples; Speciation of radionuclides in water includes: Speciation of 129I and 127I in time-series precipitation samples collected in Denmark 2001-2006 and its application for the investigation of geochemistry and atmospheric chemistry of iodine, Speciation of radionuclides in Ob and Yenisey Rivers, and Speciation of 129I and 127I in Lake Heimdalen water. Speciation of radionuclides in soils and sediments includes: Sequential extraction of radionuclides in sediments and of trace elements in soil samples. Sequential extraction of radionuclides in aerosols and particles has also been performed. Furthermore, sorption experiments have been performed to investigate the association of Pu, Am and Cs with different geological materials. The intercomparison exercises included sequential extraction of Pu, 137Cs, U, Th, and 129I in one soil and one sediment standard reference materials (NIST-4354, IAEA-375) and Pu in sediment collected from the Lake Heimdalen, Norway. (author)

  13. Determining uranium speciation in contaminated soils by molecular spectroscopic methods: Examples from the Uranium in Soils Integrated Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Allen, P.G.; Berg, J.M.; Chisholm-Brause, C.J.; Conradson, S.D.; Donohoe, R.J.; Morris, D.E.; Musgrave, J.A.; Tait, C.D.

    1994-03-01

    The US Department of Energy`s former uranium production facility located at Fernald, OH (18 mi NW of Cincinnati) is the host site for an Integrated Demonstration for remediation of uranium-contaminated soils. A wide variety of source terms for uranium contamination have been identified reflecting the diversity of operations at the facility. Most of the uranium contamination is contained in the top {approximately}1/2 m of soil, but uranium has been found in perched waters indicating substantial migration. In support of the development of remediation technologies and risk assessment, we are conducting uranium speciation studies on untreated and treated soils using molecular spectroscopies. Untreated soils from five discrete sites have been analyzed. We have found that {approximately}80--90% of the uranium exists as hexavalent UO{sub 2}{sup 2+} species even though many source terms consisted of tetravalent uranium species such as UO{sub 2}. Much of the uranium exists as microcrystalline precipitates (secondary minerals). There is also clear evidence for variations in uranium species from the microscopic to the macroscopic scale. However, similarities in speciation at sites having different source terms suggest that soil and groundwater chemistry may be as important as source term in defining the uranium speciation in these soils. Characterization of treated soils has focused on materials from two sites that have undergone leaching using conventional extractants (e.g., carbonate, citrate) or novel chelators such as Tiron. Redox reagents have also been used to facilitate the leaching process. Three different classes of treated soils have been identified based on the speciation of uranium remaining in the soils. In general, the effective treatments decrease the total uranium while increasing the ratio of U(IV) to U(VI) species.

  14. Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Karimi

    2014-01-01

    Full Text Available A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V after oxidation of As(III to As(V using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III was calculated by subtracting the concentration of As(V from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD of arsenate were 175 (for 350 mL of sample solution, 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7, respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.

  15. Phenomenological microstructure simulation of incremental bulk metal forming using a multi mesh method

    Science.gov (United States)

    Hirt, G.; Schäfer, D.

    2010-06-01

    For the process design of incremental forming processes like ring rolling or stretch forging there is need for fast and accurate simulation techniques. For many applications it would be necessary to predict the microstructural evolution during the process. For this reason the FEM-software Larstran/Shape which is used for the plastomechanical simulation can be coupled with the microstructure simulation module Strucsim. This software uses phenomenological equations for the calculation of recrystallization (dynamic and static) and grain size evolution [7]. To accelerate the simulation a multi mesh method has been developed. This method uses an adapted simulation mesh with fine elements only in the locally limited contact and forming zone to achieve a reduction of the number of elements. Due to the relative movement of the tool and workpiece the adapted FE-mesh has to be remeshed regularly according to the position of the tool. To avoid loss of information caused by the use of coarse elements the multi mesh method uses a second storage mesh which represents the entire workpiece and which is discretized using only fine elements. For the update of the storage mesh the displacement vectors and changes of scalar values like temperature can be interpolated. For the application of the multi mesh method to the microstructure simulation the update algorithm for the microstructure values has to be modified. The microstructure and plastomechanical simulation have to be uncoupled and the static recrystallization and grain growth outside the forming zone have to be calculated separately. Using the multi mesh method the simulation of incremental bulk metal forming processes including a microstructural simulation can be accelerated. The acceleration factor of the simulation compared to a simulation without adaptive meshing is dependent on the reduction of elements and nodes.

  16. New Simple UV Spectrophotometric Method for Determination of Mirtazapine in Bulk and pharmaceutical dosage forms

    Directory of Open Access Journals (Sweden)

    Sk. Benajeer

    2012-10-01

    Full Text Available Mirtazapine is chemically a tetratetracyclic (pyridodibenzazepine derivative which is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA. Mirtazapine acts as an antagonist at central pre-synaptic α2-receptors, inhibiting negative feedback to the presynaptic nerve and causing an increase in NErelease. It is also used for the treatment of Posttraumatic stress disorder. In present work, simple, sensitive, accurate and economical spectroscopic method has been developed for the estimation of mirtazapine in bulk and its pharmaceutical dosage forms. An absorption maximum was found to be at 232nm with the solvent systemphosphate buffer (pH 6.8. The drug follows beer’s law in the range of 5-30μg/ml with correlation coefficient of 0.999. The percentage recovery of mirtazapine ranged from 99.57-100.26% in pharmaceutical dosage form. Results of the analysis were validated for accuracy, precision, LOD, LOQ and were found to be satisfactory. The proposed method is simple, rapid and suitable for the routine quality control analysis.

  17. STABILIZATION OF DEWATERED SEWAGE SLUDGE BY AEROBIC COMPOSTING METHOD: USING SAWDUST AS BULKING AGENTS

    Directory of Open Access Journals (Sweden)

    A PARVARESH

    2002-12-01

    Full Text Available Introduction. Sludge production from municipal wastewater treatment plants should have quality standards before disposal in to the environment. Environmental specialists classified sewage sludge as a hazardous waste because of high organic compounds and pathogenic microorganisms. They belive that sewage should be stabilized before disposal and so composting of sewage sludge is an effective and economical method to stabilize. Sewage sludge compost could be used to improve soil structure and enrich the soil with nutrients. Methods. To evaluate the optimum conditions of aerobic compost, the mixture of dewatered sewage sludge from Isfahan municipal waste water treatment plant and sawdust as bulking agent were used. Pilot scale study were performed in Isfahan municipal waste water treatment plant. To perform this research project, the dewatered sewage sludge with humidity between 78 to 82 percent were mixed with sawdust. Turning over method of the piles with one week interval were applied to aerate the mixture. Temperature of the piles were monitored at different depths daily. Other parameters such as N, G, organic matters and pH were determined weekly. Total and fecal coli form, and salmonella were determined at the beginning and end of the composting process, also heavy metals were measured at the same time. Results. The results of this study showed that after days, temperature of the mixture reached up to 55 G, and were stabled for 15 days. Humidity, organic matter, organic carbon and GIN ratio of the mixture decreased over the period of the study, due to increasing the temperature. Also organic matter and humidity mainly decreased in thermofilic phase. The number of total and fecal coliform and also salmonella decreased to A class standards of US.EPA at the end of the operation. Discussion. The results of the study also showed that, this type of composting method is reliable, and simple to schedule, with high flexibility and low odor

  18. Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

    Science.gov (United States)

    Motwani, Sanjay K.; Chopra, Shruti; Ahmad, Farhan J.; Khar, Roop K.

    2007-10-01

    New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 μg ml -1 ( r2 = 0.9999) in hydrochloric acid and 1-14 μg ml -1 ( r2 = 0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 × 10 4 l mol -1 cm -1 and 9.5 ng cm -2/0.001 A in hydrochloric acid; and 4.08 × 10 4 l mol -1 cm -1 and 10.8 ng cm -2/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 μg ml -1 in hydrochloric acid and 0.0384, 0.1163 μg ml -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation dosage forms and dissolution studies.

  19. Factors contributing to the poor bulk behavior of meat and bone meal and methods for improving these behaviors.

    Science.gov (United States)

    Garcia, R A; Flores, R A; Mazenko, C E

    2007-11-01

    Meat and bone meal (MBM), a product of the rendering industry, is a potential feedstock for numerous bio-based applications. Design of processing equipment for MBM is difficult due to MBM's bulk behaviors; it flows less easily than many other granular materials, and it tends to foul the surfaces of processing equipment. This study examines the major factors contributing to MBM's poor bulk behavior, including moisture content, fat content, particle size distribution and temperature, and the relative importance of these factors. Potential methods for improving MBM's bulk properties, including use of an anti-caking agent, dehydration, fat extraction, milling and refrigeration are also studied. The effects of these factors were determined by a standard laboratory measurement, the Hausner ratio, as well as by the rate of surface-fouling and dust generation using a pilot-scale aspirator. In contrast to past studies with other granular materials, moisture content was shown to have an insignificant effect on MBM's bulk behavior. The results, however, show that MBM fat content is a major determinant of the bulk behavior of the MBM. Reduction of fat content resulted in major changes in MBM's bulk behavior, by all measures used. Less dramatic changes were achieved through refrigeration to solidify the fat and/or treatment with an anti-caking agent.

  20. DEVELOPMENT AND VALIDATION OF UV SPECTROPHOTOMETRIC ESTIMATION OF EBASTINE IN BULK AND TABLET DOSAGE FORM USING AREA UNDER CURVE METHOD

    Directory of Open Access Journals (Sweden)

    Dahivadkar Manish Sudhakar

    2013-06-01

    Full Text Available The aim of this work is to develop a simple, accurate, reproducible and cost effective spectrophotometric method for determination of Ebastine in bulk and pharmaceutical dosage form. This method is basedon area under curve (AUC in wavelength range of 247-257nm and method has followed linearity in the concentration range of 5-30μg/ml. Methanol was used as a solvent. The developed analytical method was validated as per International Conference on Harmonization (ICH guidelines. The value of correlation coefficient (R2 was 0.999. Limit of Detection and Limit of Quantitation were calculated as 0.78µg/ml and 2.37µg/ml, respectively. Results of the recovery studies showed good accuracy of the method. Validation results suggest that the developed method can be used for routine quality control studies for assay of Ebastine in bulk and tablet dosage form.

  1. 40 CFR Appendix E to Subpart E of... - Interim Method of the Determination of Asbestos in Bulk Insulation Samples

    Science.gov (United States)

    2010-07-01

    ... identification and quantitation of asbestos in bulk material samples that have undergone prior analysis by PLM or... must be analyzed initially for asbestos content by PLM. XRD should be used as an auxiliary method when... (sample size, homogeneity, particle size distribution, and overall composition as determined by PLM);...

  2. Investigation of preparation methods on surface/bulk structural relaxation and glass fragility of amorphous solid dispersions.

    Science.gov (United States)

    Ke, Peng; Hasegawa, Susumu; Al-Obaidi, Hisham; Buckton, Graham

    2012-01-17

    The objective of this study was to investigate the effect of preparation methods on the surface/bulk molecular mobility and glass fragility of solid dispersions. Solid dispersions containing indomethacin and PVP K30 were chosen as the model system. An inverse gas chromatography method was used to determine the surface structural relaxation of the solid dispersions and these data were compared to those for bulk relaxation obtained by DSC. The values of τ(β) for the surface relaxation were 4.6, 7.1 and 1.8h for melt quenched, ball milled and spray dried solid dispersions respectively, compared to 15.6, 7.9 and 9.8h of the bulk. In all systems, the surface had higher molecular mobility than the bulk. The glass fragility of the solid dispersions was also influenced by the preparation methods with the most fragile system showing the best stability. The zero mobility temperature (T(0)) was used to correlate with the physical stability of the solid dispersions. Despite having similar T(g) (65°C), the T(0) of the melt quenched, ball milled and spray dried samples were 21.6, -4.2 and 16.7°C respectively which correlated well with their physical stability results. Therefore, T(0) appears to be a better indicator than T(g) for predicting stability of amorphous materials.

  3. New down-hole TDR method for deep profile soil water content and bulk electrical conductivity

    Science.gov (United States)

    Comprehensive irrigation and salinity management both require accurate knowledge of field soil water content and bulk electrical conductivity to depths greater than the root zone depth in agricultural fields. Scientists at the USDA-ARS Conservation & Production Research Laboratory, Bushland, Texas, ...

  4. New method for introducing nanometer flux pinning centers into single domain YBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.M., E-mail: yangwm@snnu.edu.cn; Wang, Miao

    2013-10-15

    Highlights: • Single domain YBCO bulks with Bi{sub 2}O{sub 3} additions fabricated by TSIG process. • Nanoscale Y{sub 2}Ba{sub 4}CuBiOx(YBi2411) particles introduced by Bi{sub 2}O{sub 3} additions. • The YBi2411 particles are about 150 nm, can act as effective flux pinning centers. • The optimal addition of Bi{sub 2}O{sub 3} is 0.7wt% to achieve higher levitation force. • The result is helpful to improve the quality of REBCO bulk superconductors. -- Abstract: Single domain YBCO superconductors with different additions of Bi{sub 2}O{sub 3} have been fabricated by top seeded infiltration and growth process (TSIG). The effect of Bi{sub 2}O{sub 3} additions on the growth morphology, microstructure and levitation force of the YBCO bulk superconductor has been investigated. The results indicate that single domain YBCO superconductors can be fabricated with the additions of Bi{sub 2}O{sub 3} less than 2 wt%; Bi{sub 2}O{sub 3} can be reacted with Y{sub 2}BaCuO{sub 5} and liquid phase and finally form Y{sub 2}Ba{sub 4}CuBiO{sub x}(YBi2411) nanoscale particles; the size of the YBi2411 particles is about 100 nm, which can act as effective flux pinning centers. It is also found that the levitation force of single domain YBCO bulks is increasing from 13 N to 34 N and decreasing to 11 N with the increasing of Bi{sub 2}O{sub 3} addition from 0.1 wt% to 0.7 wt% and 2 wt%. This result is helpful for us to improve the physical properties of REBCO bulk superconductors.

  5. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    Science.gov (United States)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2009-01-01

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included.

  6. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Pereira, Francisco; Lavilla, Isela [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Quimica, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo (Spain); Bendicho, Carlos [Departamento de Quimica Analitica y Alimentaria, Area de Quimica Analitica, Facultad de Quimica, Universidad de Vigo, Campus As Lagoas-Marcosende s/n, 36310 Vigo (Spain)], E-mail: bendicho@uvigo.es

    2009-01-15

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included.

  7. Free-space reflection method for measuring moisture content and bulk density of particulate materials at microwave frequency

    Science.gov (United States)

    Li, Chenxiao; Han, Bing; Zhang, Tao

    2015-03-01

    A measurement system based on free-space reflection method is designed for simultaneous and independent determination of moisture content and bulk density of particulate materials. The proposed system consists of microwave cavity oscillator, horn antenna, slide rail, sample holder, mixer, and digital meter. Sand and rice with different moisture contents and bulk densities are chosen as samples. Calibration models for moisture content and bulk density are proposed according to the measurement of the position of the minimum of the traveling-standing wave and the ratio of the maximum-to-minimum field strength of the traveling-standing wave at different temperatures. The moisture constant, ranging from 0% to 24.6%, is obtained with a coefficient of determination (R2) greater than 0.982 and a standard error of prediction (SEP) value of less than 0.695%. The bulk density, ranging from 0.501 g/cm3 to 1.822 g/cm3, is determined with a R2 ≥ 0.961 and a SEP value ranging from 0.0144 g/cm3 to 0.0382 g/cm3 for different samples.

  8. RP-HPLC Method for the Determination of Cinitapride in the Presence of its Degradation Products in Bulk Drug

    Directory of Open Access Journals (Sweden)

    S. M. N. Roy

    2010-01-01

    Full Text Available A reverse phase HPLC method is described for the determination of cinitapride hydrogen tartrate in the presence of its degradation products in bulk drug. A drug was subjected to all stress conditions such as reduction, oxidation acidic and alkaline medium. Chromatography was recorded on an Intersil ODS-3 column using mixture of acetonitrile and phosphate buffer, pH adjusted to 6.7 in the ratio (70:30 v/v as the mobile phase at the rate of 1.0 mL/min with detection at 260 nm. Glimepride was used as internal standard. The retention time of drug cinitapride was 3.8 min and glimepride an internal standard was 2.5 minute. The drug was found to degrade extensively in reduction conditions and mild degradation in the presence of in alkaline, acidic and oxidative but the drug was stable in thermal stress. The method was validated by determining its specificity, linearity, precision and accuracy. The developed method with good separation of all degradation products from drug could be successfully applied for the determination of cinitapride in the presence of its degradation products in the bulk drug. The proposed method is simple, fast, accurate and precise and hence applied for routine quality control of cinitapride in bulk drug. It can be used for analysis of samples during stability testing.

  9. Standard Test Method for Water Absorption, Bulk Density, Apparent Porosity, and Apparent Specific Gravity of Fired Whiteware Products

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This test method covers procedures for determining water absorption, bulk density, apparent porosity, and apparent specific gravity of fired unglazed whiteware products. 1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  10. Analytical method development and validation of Drotaverine Hydrochloride and Aceclofenac in bulk and pharmaceutical dosage forms by UV-Spectrophotometer

    OpenAIRE

    Ram Babu Durgam; Sireesha. D; V. V. L. N Prasad; Diwan, Prakash V.

    2013-01-01

    New simple, precise, rapid and reproducible UV-spectrophotometric method has been developed for the estimation of Drotaverine Hydrochloride and Aceclofenac in both bulk and tablet formulation. Drotaverine and Aceclofenac in combined tablet formulation were estimated by using the multicomponent mode at 307 nm for Drotaverine and 276 nm for Aceclofenac in their solution in ethanol: distilled water in the ratio of 50:50 (v/v %), With correlation coefficient of 0.999 for the both the drugs. The B...

  11. The effect of hygroscopicity on sea-spray aerosol fluxes: a comparison of high-rate and bulk correction methods

    Directory of Open Access Journals (Sweden)

    D. A. J. Sproson

    2012-09-01

    Full Text Available The eddy covariance technique is the most direct of the methods that have been used to measure the flux of sea-spray aerosol between the ocean and atmosphere, but has been applied in only a handful of studies. However, unless the aerosol is dried before the eddy covariance measurements are made, the hygroscopic nature of sea-spray may combine with a relative humidity flux to result in a bias in the calculated aerosol flux. "Bulk" methods have been presented to account for this bias, however they rely on assumptions of the shape of the aerosol spectra which may not be valid for near-surface measurements of sea-spray.

    Here we describe a method of correcting aerosol spectra for relative humidity induced size variations at the high frequency (10 Hz measurement timescale, where counting statistics are poor and the spectral shape cannot be well represented by a simple power law. Such a correction allows the effects of hygroscopicity and relative humidity flux on the aerosol flux to be explicitly evaluated and compared to the bulk corrections, both in their original form and once reformulated to better represent the measured mean aerosol spectra. In general, the bulk corrections – particularly when reformulated for the measured mean aerosol spectra – perform relatively well, producing flux corrections of the right sign and approximate magnitude. However, there are times when the bulk methods either significantly over- or underestimate the required flux correction. We thus conclude that, where possible, relative humidity corrections should be made at the measurement frequency.

  12. A heuristic and hybrid method for the tank allocation problem in maritime bulk shipping

    DEFF Research Database (Denmark)

    Vilhelmsen, Charlotte; Larsen, Jesper; Lusby, Richard Martin

    2016-01-01

    In bulk shipping, ships often have multiple tanks and carry multiple inhomogeneous products at a time. When operating such ships it is therefore a major challenge to decide how to best allocate cargoes to available tanks while taking into account tank capacity, safety restrictions, ship stability...... and strength as well as other operational constraints. The problem of finding a feasible solution to this tank allocation problem has been shown to be NP-Complete. We approach the problem on a tactical level where requirements for computation time are strict while solution quality is less important than simply...

  13. Estimation of critical current density and grain connectivity in superconducting MgB 2 bulk using Campbell’s method

    Science.gov (United States)

    Ni, B.; Morita, Y.; Liu, Z.; Liu, C.; Himeki, K.; Otabe, E. S.; Kiuchi, M.; Matsushita, T.

    2008-09-01

    Many recent reports on the critical current density ( Jc) in superconducting MgB 2 bulks indicated that improving the grain connectivity is important, since the obtained Jc values were generally much lower than those in other metallic superconductors and it was ascribed to the poor connectivity between grains in polycrystalline MgB 2. In this study, we focused on the estimation of the global critical current density, super-current path, grain connectivity and their relationships with the faults volume fraction in the MgB 2 bulks prepared by a modified PIT (powder in tube) method. Campbell’s method was applied for the purpose of obtaining the penetrating AC flux profile and the characteristic of AC magnetic field vs. penetration depth from the sample’s surface. A computer simulation on the penetrating AC flux profile in MgB 2 bulks with randomly distributed voids, oxidized grains and other faults was also carried out. Jc obtained by Campbell’s method turned out to be smaller than that obtained from the SQUID measurement, implying that the global super-current was reduced by the existence of various faults and the lack of the electrical connectivity. It was verified that the relationship between the global critical current characteristics and the faults contained in MgB 2 samples can be quantitatively clarified by comparing the simulated critical current densities and other factors with the experimental results.

  14. A highly sensitive fluorimetric method for determination of lenalidomide in its bulk form and capsules via derivatization with fluorescamine

    Directory of Open Access Journals (Sweden)

    Darwish Ibrahim A

    2012-10-01

    Full Text Available Abstract Background Lenalidomide (LND is a potent novel thalidomide analog which demonstrated remarkable clinical activity in treatment of multiple myeloma disease via a multiple-pathways mechanism. The strong evidences-based clinical success of LND in patients has led to its recent approval by US-FDA under the trade name of Revlimid® capsules by Celgene Corporation. Fluorimetry is a convenient technique for pharmaceutical quality control, however there was a fluorimetric method for determination of LND in its bulk and capsules. Results A novel highly sensitive and simple fluorimetric method has been developed and validated for the determination of lenalidmide (LND in its bulk and dosage forms (capsules. The method was based on nucleophilic substitution reaction of LND with fluorescamine (FLC in aqueous medium to form a highly fluorescent derivative that was measured at 494 nm after excitation at 381 nm. The factors affecting the reaction were carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was postulated. Under the optimized conditions, linear relationship with good correlation coefficient (0.9999 was found between the fluorescence intensity and LND concentration in the range of 25–300 ng/mL. The limits of detection and quantitation for the method were 2.9 and 8.7 ng/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 1.4%. The proposed method was successfully applied to the determination of LND in its bulk form and pharmaceutical capsules with good accuracy; the recovery values were 97.8–101.4 ± 1.08–2.75%. Conclusions The proposed method is selective and involved simple procedures. In conclusion, the method is practical and valuable for routine application in quality control laboratories for determination of LND.

  15. Electrodynamic balance measurements of thermodynamic, kinetic, and optical aerosol properties inaccessible to bulk methods

    Directory of Open Access Journals (Sweden)

    S. S. Steimer

    2015-06-01

    Full Text Available Measurements of a single, levitated particle in an electrodynamic balance are an established tool for deriving thermodynamic and material data such as density, refractive index and activities of components of an aqueous solution under supersaturated conditions, where bulk measurements are not possible. The retrieval relies on combining mass-to-charge data and size data from light scattering. Here, we use a combination of low- and high-resolution Mie resonance spectroscopy to obtain radius data, enabling an accurate size determination not only when the particle is in equilibrium, but also when it is out of equilibrium due to kinetic limitation of mass transport. With the data measured under non-equilibrium conditions, it is possible to retrieve the water diffusivity. A challenge is that the radius retrieval by comparing measured light scattering with Mie theory requires the knowledge of refractive index as a function of concentration. Here, we show an iterative retrieval of refractive index and size for compounds for which data cannot be obtained in the bulk either due to lack of sufficient amounts of sample or limited solubility. We demonstrate the measurement strategy and the retrieval of water activity, density, refractive index and water diffusivity for aqueous shikimic acid. Water diffusivity in concentrated shikimic acid decreases by 6 orders of magnitude at 250 K compared to that at room temperature.

  16. Electrodynamic balance measurements of thermodynamic, kinetic, and optical aerosol properties inaccessible to bulk methods

    Directory of Open Access Journals (Sweden)

    S. S. Steimer

    2015-01-01

    Full Text Available Measurements of a single, levitated particle in an electrodynamic balance are an established tool for deriving thermodynamic and material data such as density, refractive index and activities of components of an aqueous solution under supersaturated conditions, where bulk measurements are not possible. The retrieval relies on combining mass-to-charge data and size data from light scattering. Here, we use a combination of low- and high-resolution Mie resonance spectroscopy to obtain radius data, enabling an accurate size determination not only when the particle is in equilibrium, but also when it is out of equilibrium due to kinetic limitation of mass transport. With the data measured under non-equilibrium conditions, it is possible to retrieve the water diffusivity. A challenge is that the radius retrieval by comparing measured light scattering with Mie theory requires the knowledge of refractive index as a function of concentration. Here, we show an iterative retrieval of refractive index and size for compounds for which data cannot be obtained in the bulk either due to lack of sufficient amounts of sample or limited solubility. We demonstrate the measurement strategy and the retrieval of water activity, density, refractive index and water diffusivity for aqueous shikimic acid. Water diffusivity in concentrated shikimic acid decreases by 6 orders of magnitude at 250 K compared to that at room temperature.

  17. Fast methods of computing bulk radiative properties of inhomogeneous clouds illuminated by solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, P. [Colorado State Univ., Fort Collins, CO (United States)

    1995-09-01

    The use of cloud fraction as a means of incorporating horizontal cloud inhomogeneity in radiative transfer calculations is widespread in the atmospheric science community. This research attempts to bypass the use of cloud fraction in radiative transfer modeling for two-dimensional media. Gabriel describes two approximation techniques useful in calculating the domain averaged bulk radiative properties such as albedo, flux divergence and mean radiance that dispense with the need to use cloud fraction as a specifier of cloud inhomogeneity. The results suggest that the variability of the medium can largely be accounted for through the pseudo-source term, offering hope of parameterizing the equation of transfer in terms of the statistical properties of the medium. 1 fig.

  18. Development of Stability Indicating LC Method for the Estimation of Tolperisone in Bulk and Pharmaceutical Dosage Form

    OpenAIRE

    Chhalotiya, U. K.; Bhatt, K. K.; Shah, D. A.; S. L. Baldania; Patel, S.B.

    2013-01-01

    A rapid, specific, and sensitive reverse phase high performance liquid chromatographic method has been developed and validated for analysis of tolperisone in both bulk and pharmaceutical dosage form. The HPLC method was performed with a reversed phase C18 SunFire column (250 mm × 4.6 mm i.d., 5 mm particle size), detection at 261 nm and a mixture of methanol, water and pH 7.5 adjusted by use of 1% solution of triethylamine (60 : 40) as mobile phase. The flow rate was 1.0 mL min−1 and effluent...

  19. STABILITY INDICATING RP-LC METHOD FOR DETERMINATION OF RASAGILINE MESYLATE IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    OpenAIRE

    R. Narendra Kumar; Nageswara Rao, G.; P.Y. Naidu

    2010-01-01

    An isocratic stability indicating liquid chromatographic method has been developed and validated for the determination of Rasagiline in bulk drug and its pharmaceutical dosage forms. Separation of the drug with degradation products was achieved using Puroshere Star, C18, 150 x 4.6mm; 5μm column as stationary phase and pH 7.0(±0.05) buffer: Acetonitrile (40:60,v/v) as mobile phase at a flow rate of 1.0 mL/min. UV detection was performed at 210 nm. The method is linear over the range of 4.8 – 1...

  20. Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: 1. Analysis of Individual Particles Using Complementary Microprobe Methods.

    Science.gov (United States)

    Desyaterik, Y.; Hopkins, R. J.; Tivanski, A. V.; Berkowitz, C. M.; Gilles, M. K.; Laskin, A.

    2006-12-01

    Chemical speciation of dry residues of individual cloud droplets and interstitial aerosol collected from sea-fog during the Marine Stratus Experiment (MASE) in July 2005 was facilitated using a complementary combination of computer controlled scanning electron microscopy with energy dispersed analysis of x-rays (CCSEM/EDX), time-of-flight secondary ionization mass spectrometry (TOF-SIMS), and scanning transmission x-ray microscopy with near edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS). Particle samples were collected at the ground site located in Pt. Reyes National Seashore, about 0.5 miles from the ocean coast over the period of time when the air plume, that originated over the open ocean, passed the area of the cold stream along the northern California coast. Based on composition, morphology, and microstructure, two externally mixed, distinct types of sea-fog particles were identified in the samples: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate excessive formation of methanesulfonate (CH3SO3-) rather then non-sea-salt sulfate (nss-SO42-) in the sea salt particles. This observation is consistent with the recent modeling studies of dimethylsulfide (DMS) oxidation chemistry in the marine boundary layer (MDL). Modeling studies predict enhanced formation of CH3SO3- in activated sea salt particles under cloudy MBL conditions over the areas with low ocean surface temperatures. We discuss the climate related effects of this chemistry which likely results in: a) increasing size and hygroscopicity of the pre-existing CCN (sea salt particles), and b) reducing the production of gaseous H2SO4 and subsequent new sulfate particle formation.

  1. Evaluation of Trapped Magnetic Field Properties in Superconducting MgB2 Bulk Magnets of Various Shapes by Finite Element Method

    Science.gov (United States)

    Hiramatsu, Y.; Otabe, E. S.; Kiuchi, M.

    The trapped magnetic field properties of superconducting MgB2 bulk magnets with various shapes such as a triangular, a quadrangular, a hexangular bulk were calculated by the Finite Elements Method (FEM). The effect for the combination of several numbers of bulks was also investigated for several kinds of shapes to obtain large area of bulk surface in spite of one large bulk. In this calculation, the simple magnetization process replaced by the field-cool magnetization was used to obtain the equivalent distribution of the magnetic field, and the thermal equation in FEM was omitted. The trapped magnetic field for the triangular bulk by FEM was compared with the experimental result. It was found that the calculated results agreed well with the experimental result. The maximum trapped magnetic field was obtained in the cylindrical shape among several kinds of shapes. The trapped magnetic field was increased by the combination of multi-bulks. It was confirmed that the trapped magnetic field of the multi-bulks was larger than that of the single bulk. The trapped magnetic field increases with increasing the number of the bulks.

  2. A method to search for bulk motions in the ICM with {\\sl Chandra} CCD spectra: application to the Bullet cluster

    CERN Document Server

    Liu, Ang; Tozzi, Paolo; Zhu, Zong-Hong

    2015-01-01

    We propose a strategy to search for bulk motions in the intracluster medium (ICM) of merging clusters based on {\\sl Chandra} CCD data. Our goal is to derive robust measurements of the average redshift of projected ICM regions obtained from the centroid of the $K_\\alpha$ line emission. We thoroughly explore the effect of the unknown temperature structure along the line of sight to accurately evaluate the systematic uncertainties on the ICM redshift. We apply our method to the "Bullet cluster" (1E~0657-56). We directly identify 23 independent regions on the basis of the surface brightness contours, and measure the redshift of the ICM averaged along the line of sight in each. We find that the redshift distribution across these regions is marginally inconsistent with the null hypothesis of a constant redshift or no bulk motion in the ICM, at a confidence level of about $2\\, \\sigma$. We tentatively identify the regions most likely affected by bulk motions and find a maximum velocity gradient of about $(46\\pm 13)$ ...

  3. Bulk single crystal growth of SiGe by PMCZ method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Weilian; NIU Xinhuan; CHEN Hongjian; ZHANG Jianxin; SUN Junsheng; ZHANG Enhuai

    2003-01-01

    A new type of magnetic device was used to replace the conventional electro-magnetic field for CZSi (doped with Ge) growth. The device was composed of three permanent magnetic rings and called PMCZ device. The lines of magnetic force are horizontally distributed at radial 360°. Using the ring permanent magnetic field, thermal convection in melt and centrifugal pumping flows due to crystal rotation could be strongly suppressed so that the fluctuations of temperature and micro-growth rate at solid/liquid interface could be restrained effectively. In the PMCZ condition, the growing environment of SiGe bulk single crystal was similar to the crystal growth in space under the condition of micro-gravity. The motion of impurities (Ge, oxygen, etc.) had been controlled by diffusion near the solid/liquid interface. Oxygen concentraion became lower and the distribution of composition became more homogeneous along longitudinal direction and across a radial section in the grown SiGe crystal. The mechanism of PMCZ superior to MCZ was also discussed.

  4. Searching for speciation genes

    DEFF Research Database (Denmark)

    Holt, Benjamin George; Côté, Isabelle M; Emerson, Brent C

    2011-01-01

    Closely related species that show clear phenotypic divergence, but without obvious geographic barriers, can provide opportunities to study how diversification can occur when opportunities for allopatric speciation are limited. We examined genetic divergence in the coral reef fish genus Hypoplectrus...

  5. Development and Validation of Simple UV Spectrophotometric Method for the Estimation of Dextromethorphan Hydrobromide in Bulk and Marketed Dosage Formulations

    Directory of Open Access Journals (Sweden)

    Vineeta V. Khanvilkar

    2016-05-01

    Full Text Available A simple, rapid and economic UV spectrophotometric method has been developed and validated using a solvent 0.1N HCl to determine Dextromethorphan hydrobromide content in bulk and two different pharmaceutical solid dosage formulations, lozenges and chewable tablets. At the pre-determined λmax of 278 nm, it was proved linear in the range of 5.0-30.0 µg/ml and exhibited good correlation coefficient (R2=0.9993 and excellent mean recovery (101.37-100.76% and (100.66-101.17% for lozenges and chewable tablets respectively. This method was successfully applied to the determination of Dextromethorphan hydrobromide content in lozenges and chewable tablets and the results were in good agreement with the label claim. The method was validated as per ICH guidelines for linearity, precision, accuracy, specificity, LOD and LOQ. The obtained results proved that the method can be employed for the routine analysis of Dextromethorphan hydrobromide in bulks as well as in the pharmaceutical formulations.

  6. What Is Speciation?

    Science.gov (United States)

    Shapiro, B Jesse; Leducq, Jean-Baptiste; Mallet, James

    2016-03-01

    Concepts and definitions of species have been debated by generations of biologists and remain controversial. Microbes pose a particular challenge because of their genetic diversity, asexual reproduction, and often promiscuous horizontal gene transfer (HGT). However, microbes also present an opportunity to study and understand speciation because of their rapid evolution, both in nature and in the lab, and small, easily sequenced genomes. Here, we review how microbial population genomics has enabled us to catch speciation "in the act" and how the results have challenged and enriched our concepts of species, with implications for all domains of life. We describe how recombination (including HGT and introgression) has shaped the genomes of nascent microbial, animal, and plant species and argue for a prominent role of natural selection in initiating and maintaining speciation. We ask how universal is the process of speciation across the tree of life, and what lessons can be drawn from microbes? Comparative genomics showing the extent of HGT in natural populations certainly jeopardizes the relevance of vertical descent (i.e., the species tree) in speciation. Nevertheless, we conclude that species do indeed exist as clusters of genetic and ecological similarity and that speciation is driven primarily by natural selection, regardless of the balance between horizontal and vertical descent.

  7. A Validated TLC-Densitometric Method for the Determination of Mesterolone in Bulk Material and in Tablets.

    Science.gov (United States)

    Dołowy, Małgorzata; Pyka-Pająk, Alina; Filip, Katarzyna; Zagrodzka, Joanna

    2015-01-01

    Mesterolone is a synthetic androgenic steroid indicating a weak anabolic activity. A new, simple in use, and economical TLC-densitometric method in normal phase system (NP-TLC) has been developed and validated for the identification and quantitative determination of mesterolone in bulk drug and in tablet formulation. NP-TLC analysis was performed on aluminium plates precoated with silica gel 60F254 as the stationary phase using chloroform-acetone (40 : 10, v/v) as mobile phase. Densitometric analysis was carried out at λ = 745 nm after staining with phosphomolybdic acid. These conditions were found to give visible (dark blue) spot and sharp peak, respectively, for mesterolone at R F 0.75 ± 0.02 and enabled satisfactory separation of mesterolone from its related substance (potential impurity). The proposed NP-TLC-densitometric method was validated for specificity, linearity, precision, accuracy, robustness, and sensitivity according to ICH guideline and other validation requirements. The limit of detection (LOD) and limit of quantification (LOQ) were 61.0 ng · spot(-1) and 184.0 ng · spot(-1), respectively. The percent content of mesterolone in marketed tablet formulation was found to be 99.40% of label claim. The developed TLC-densitometric method can be successfully used in quality control of mesterolone in bulk material and also tablet formulation.

  8. Development and validation of a HPTLC method for estimation of duloxetine hydrochloride in bulk drug and in tablet dosage form

    Directory of Open Access Journals (Sweden)

    Dhaneshwar Suneela

    2008-01-01

    Full Text Available Duloxetine hydrochloride is a potent dual reuptake inhibitor of serotonin and norepinephrine used to treat major depressive disorders. The present work describes a simple, precise and accurate HPTLC method for its estimation as bulk and in tablet dosage form. The chromatographic separation was carried out on precoated silica gel 60 F254 aluminium plates using mixture of chloroform:methanol (8:1 v/v as mobile phase and densitometric evaluation of spots was carried out at 235 nm using Camag TLC Scanner-3 with win CAT 1.3.4 version software. The experimental parameters like band size of the spot applied, chamber saturation time, solvent front migration, slit width etc. were critically studied and optimum conditions were evolved. The drug was satisfactorily resolved with Rf value 0.11±0.01. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity (40-200 ng/spot, precision (intra-day RSD 0.46-0.75%, inter-day RSD 0.46-1.59%, accuracy (98.72±0.20 and specificity according to ICH guidelines. The proposed method can analyse ten or more formulation units simultaneously on a single plate and provides a faster and cost-effective quality control tool for routine analysis of duloxetine hydrochloride as bulk drug and in tablet formulation.

  9. Rapid estimation of tadalafil by reverse-phase high-performance liquid chromatography method in bulk and tablet formulation

    Directory of Open Access Journals (Sweden)

    P H Sonawane

    2013-01-01

    Full Text Available The simple, selective, precise and accurate reverse-phase high-performance liquid chromatography method was developed and validated for analysis of tadalafil in bulk and tablet dosage form. The column was Inertsil C18 (150×4.6 mm; 5 μm in isocratic mode. The mobile phase used was phosphate buffer (10 mM, pH 3.2 and acetonitrile (50:50% v/v at the flow rate of 1.0 ml/min with ultraviolet detection at 295 nm at ambient temperature. The retention time for tadalafil was found to be 4.01 min. Linearity was observed in the concentration range from 60 to 140 μg/ml for tadalafil with a correlation coefficient of (r2 0.9998. The method was validated according to International Conference on Harmonisation guidelines in terms of linearity, accuracy, precision and specificity. Hence, the proposed method can be utilized for routine quality control of tadalafil in bulk and tablet dosage form.

  10. Simple and sensitive spectrophotometric methods for the analysis of mesalamine in bulk and tablet dosage forms

    Directory of Open Access Journals (Sweden)

    Bala Sekaran Chandra

    2011-01-01

    Full Text Available Three simple, sensitive, economical and reproducible spectrophotometric methods (A, B and C are described for determination of mesalamine in pure drug as well as in tablet dosage forms. Method A is based on the reduction of tungstate and/or molybdate in Folin Ciocalteu's reagent; method B describes the reaction between the diazotized drug and α-naphthol and method C is based on the reaction of the drug with vanillin, in acidic medium. Under optimum conditions, mesalamine could be quantified in the concentration ranges, 1-30, 1-15 and 2-30 µg mL-1 by method A, B and C, respectively. All the methods have been applied to the determination of mesalamine in tablet dosage forms. Results of analysis are validated statistically.

  11. STABILITY INDICATING RP-LC METHOD FOR DETERMINATION OF RASAGILINE MESYLATE IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    Directory of Open Access Journals (Sweden)

    R. Narendra Kumar

    2010-10-01

    Full Text Available An isocratic stability indicating liquid chromatographic method has been developed and validated for the determination of Rasagiline in bulk drug and its pharmaceutical dosage forms. Separation of the drug with degradation products was achieved using Puroshere Star, C18, 150 x 4.6mm; 5μm column as stationary phase and pH 7.0(±0.05 buffer: Acetonitrile (40:60,v/v as mobile phase at a flow rate of 1.0 mL/min. UV detection was performed at 210 nm. The method is linear over the range of 4.8 – 150.5 μg/mL. The percent recovery of drug in dosage forms was ranged from 98.0 to 102.1. The method is simple, rapid, precise, selective and stability indicating and can be used for the assay in quality control and stability studies samples.

  12. Extractive Spectrophotometric Methods for the Determination of Zolmitriptan in Bulk Drug and Pharmaceutical Formulation Using Bromocresol Green

    Science.gov (United States)

    Prashanth, K. N.; Swamy, N.; Basavaiah, K.

    2013-11-01

    Considering the basic property of zolmitriptan (ZMT) to generate ion-pairs with sulfonephthalein dyes two methods have been developed for its assay in bulk drug and dosage form. The first method (method A) is based on the formation of a colored ion-pair complex (1:1 drug:dye) of ZMT with bromocresol green (BCG) at pH 4.20 ± 0.01 and extraction of the complex into chloroform followed by measurement of the yellow ion-pair complex at 435 nm. In the second method (method B), the drug-dye ion-pair complex was treated with ethanolic potassium hydroxide in ethanolic medium and the resulting base form of the dye was measured at 630 nm. Beer's law was obeyed in the concentration range of 0.8-18.0 and 0.08-1.4 μg/ml for method A and B, respectively, and the corresponding molar absorptivity values were 1.50ṡ104 and 1.52ṡ105 l/(molṡcm). The Sandell sensitivity values were 0.0191 and 0.0019 μg/cm2 for method A and method B, respectively. The stoichiometry of the ion-pair complex formed between the drug and dye (1:1) was determined by Job's continuous variation method and the stability constant of the complex was also calculated. The proposed method was successfully extended to dosage form (tablets).

  13. Plastic scintillators for positron emission tomography obtained by the bulk polymerization method

    CERN Document Server

    Kapłon, Łukasz; Molenda, Marcin; Moskal, Paweł; Wieczorek, Anna; Bednarski, Tomasz; Białas, Piotr; Czerwiński, Eryk; Korcyl, Grzegorz; Kowal, Jakub; Kowalski, Paweł; Kozik, Tomasz; Krzemień, Wojciech; Niedźwiecki, Szymon; Pałka, Marek; Pawlik, Monika; Raczyński, Lech; Rudy, Zbigniew; Salabura, Piotr; Gupta-Sharma, Neha; Silarski, Michał; Słomski, Artur; Smyrski, Jerzy; Strzelecki, Adam; Wiślicki, Wojciech; Zieliński, Marcin; Zoń, Natalia

    2015-01-01

    This paper describes three methods regarding the production of plastic scintillators. One method appears to be suitable for the manufacturing of plastic scintillator, revealing properties which fulfill the requirements of novel positron emission tomography scanners based on plastic scintillators. The key parameters of the manufacturing process are determined and discussed.

  14. Structure and properties of Fe-Cr-Mo-C bulk metallic glasses obtained by die casting method

    Directory of Open Access Journals (Sweden)

    W. Pilarczyk

    2010-09-01

    Full Text Available urpose: The goal of this work is to investigate structure and properties of Fe54Cr16Mo12C18 alloy rods with different diameters obtained by the pressure die casting method.Design/methodology/approach: Master alloy ingot with compositions of Fe54Cr16Mo12C18 was prepared by induction melting of pure Fe, Cr, Mo, C elements in argon atmosphere. The investigated material were cast in form of rods with different diameters. Glassy and crystalline structures were examined by X-ray diffraction. The microscopic observation of the fracture morphology was carried out by the SEM with different magnification. The thermal properties of the studied alloy were examined by DTA and DSC method.Findings: These materials exhibit high glass-forming ability, excellent mechanical properties and corrosion resistance.Research limitations/implications: It is difficult to obtain a metallic glass of Fe54Cr16Mo12C18 alloy. The investigations carried out on the different samples of Fe54Cr16Mo12C18 bulk metallic alloy allowed to state that the studied ribbon was amorphous whereas rods were amorphous – crystalline.Originality/value: The formation and investigation of the casted Fe-Cr-Mo-C bulk materials and the study of glass-forming ability of this alloy.

  15. Potential sources and processes affecting speciated atmospheric mercury at Kejimkujik National Park, Canada: comparison of receptor models and data treatment methods

    Science.gov (United States)

    Xu, Xiaohong; Liao, Yanyin; Cheng, Irene; Zhang, Leiming

    2017-01-01

    Source apportionment analysis was conducted with positive matrix factorization (PMF) and principal component analysis (PCA) methods using concentrations of speciated mercury (Hg), i.e., gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), and other air pollutants collected at Kejimkujik National Park, Nova Scotia, Canada, in 2009 and 2010. The results were largely consistent between the 2 years for both methods. The same four source factors were identified in each year using PMF method. In both years, factor photochemistry and re-emission had the largest contributions to atmospheric Hg, while the contributions of combustion emission and industrial sulfur varied slightly between the 2 years. Four components were extracted with air pollutants only in each year using PCA method. Consistencies between the results of PMF and PCA include (1) most or all PMF factors overlapped with PCA components, (2) both methods suggest strong impact of photochemistry but little association between ambient Hg and sea salt, and (3) shifting of PMF source profiles and source contributions from one year to another was echoed in PCA. Inclusion of meteorological parameters led to identification of an additional component, Hg wet deposition in PCA, while it did not affect the identification of other components. The PMF model performance was comparable in 2009 and 2010. Among the three Hg forms, the agreements between model-reproduced and observed annual mean concentrations were excellent for GEM, very good for PBM, and acceptable for GOM. However, on a daily basis, the agreement was very good for GEM but poor for GOM and PBM. Sensitivity tests suggest that increasing sample size by imputation is not effective in improving model performance, while reducing the fraction of concentrations below method detection limit, by either scaling GOM and PBM to higher concentrations or combining them to reactive mercury, is effective. Most of the data

  16. Method development for the redox speciation analysis of iron by ion chromatography-inductively coupled plasma mass spectrometry and carryover assessment using isotopically labeled analyte analogues.

    Science.gov (United States)

    Wolle, Mesay Mulugeta; Fahrenholz, Timothy; Rahman, G M Mizanur; Pamuku, Matt; Kingston, H M 'Skip'; Browne, Damien

    2014-06-20

    An ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS) method was developed for the redox speciation analysis of iron (Fe) based on in-column complexation of Fe(2+) and Fe(3+) by dipicolinic acid (DPA). The effects of column type, mobile phase composition and molecular ion interference were studied in the method optimization. The carryover of the target species in the IC-ICP-MS method was uniquely and effectively evaluated using isotopically enriched analogues of the analytes ((54)Fe(2+) and (57)Fe(3+)). Standard solutions of the enriched standards were injected into the system following analysis of a sample, and the ratios of the isotopes of iron in the enriched standards were calculated based on the chromatographic peak areas. The concentrations of the analytes carried over from the sample to the enriched standards were determined using the quantitative relationship in isotope dilution mass spectrometry (IDMS). In contrast to the routine way of evaluating carryover effect by injecting a blank solution after sample analysis, the use of isotopically enriched standards identified significant analyte carryover in the present method. Extensive experiments were carried out to systematically identify the source of the carryover and to eliminate the problem; the separation column was found to be the exclusive source. More than 95% of the analyte carryover was eliminated by reducing the length of the column. The detection limit of the IC-ICP-MS method (MDL) for the iron species was 2ngg(-1). The method was used to determine Fe(2+) and Fe(3+) in synthetic aqueous standard solutions and a beverage sample.

  17. A Heuristic and Hybrid Method for the Tank Allocation Problem in Maritime Bulk Shipping

    DEFF Research Database (Denmark)

    Vilhelmsen, Charlotte; Larsen, Jesper; Lusby, Richard Martin

    and strength as well as other operational constraints. The problem of finding a feasible solution to this tank allocation problem has been shown to be NP-Complete. We approach the problem on a tactical level where requirements for computation time are strict while solution quality is less important than simply...... have created a hybrid method that first runs the heuristic and if the heuristic fails to solve the problem, then runs the modified optimality based method on the parts of the problem that the heuristic did not solve. This hybrid method cuts between 90% and 94% of the average running times compared...... finding a feasible solution. We have developed a heuristic that can efficiently find feasible cargo allocations. Computational results show that it can solve 99% of the considered instances within 0.4 seconds and all of them if allowed longer time. We have also modified an optimality based method from...

  18. New spectrofluorimetric method for the determination of nizatidine in bulk form and in pharmaceutical preparations

    Science.gov (United States)

    Karasakal, Ayça; Ulu, Sevgi Tatar

    2013-08-01

    A simple, accurate and highly sensitive spectrofluorimetric method has been developed for determination of nizatidine in pure form and in pharmaceutical dosage forms. The method is based on the reaction between nizatidine and 1-dimethylaminonaphthalene-5-sulphonyl chloride in carbonate buffer, pH 10.5, to yield a highly fluorescent derivative peaking at 513 nm after excitation at 367 nm. Various factors affecting the fluorescence intensity of nizatidin-dansyl derivative were studied and conditions were optimized. The method was validated as per ICH guidelines. The fluorescence concentration plot was rectilinear over the range of 25-300 ng/mL. Limit of detection and limit of quantification were calculated as 11.71 and 35.73 ng/mL, respectively. The proposed method was successfully applied to pharmaceutical preparations.

  19. Simultaneous Estimation of Fluoxetine HCl and Olanzapine in Bulk Drug and Pharmaceutical Formulation by Using UV-Visible Spectroscopy Method

    Directory of Open Access Journals (Sweden)

    Rubesh kumar S

    2011-01-01

    Full Text Available Present work is to carry out an analytical method development and validation of Fluoxetine HCl (FLU and Olanzapine (OLZ in bulk drug and pharmaceutical dosage form. The developed method is based upon simultaneous equations (Vierodt’s method by using UV/Visible spectroscopy. Both drugs come in the categories of anti- depressant and anti-psychotic agent. The developed method can be used for the simultaneous estimation of FLU and OLZ in pharmaceutical dosage form without separating from each other or from the excipients. Primarily the λ max of Fluoxetine HCl (FLU and Olanzapine (OLZ was determined as 226 and 258 nm respectively. The suggested method is validated by using ICH validation parameters like accuracy, precession, linearity and LOD and LOQ respectively. Accuracy study showed percentage recovery in the range of 97-102% w/w respectively. Precision studies were carried out for 6 successive absorbance and studied for their percentage relative standard deviation (%RSD was < 2%, LOD and LOQ was studied and the limit of detection and limit of quantification were found to be was 1-100 µg/ml for Olanzapine and Fluoxetine HCl, the slope of interception Y=0.23x6+0.054 (R2 0.993 and Y=0.222x6-0.014 (R 2 0.995 respectively. Relative standard deviation for Fluoxetine hydrochloride and Olanzapine were 0.4904 and 0.53969, the co-relation coefficient were 0.997 and 0.825 respectively. This procedure was applied successfully for the analysis of FLU and OLZ in bulk drug and Pharmaceutical preparations.

  20. Development and validation spectroscopic methods for the determination of lomefloxacin in bulk and pharmaceutical formulations

    Science.gov (United States)

    El-Didamony, A. M.; Hafeez, S. M.

    2016-01-01

    Four simple, sensitive spectrophotometric and spectrofluorimetric methods (A-D) for the determination of antibacterial drug lomefloxacin (LMFX) in pharmaceutical formulations have been developed. Method A is based on formation of ternary complex between Pd(II), eosin and LMFX in the presence of methyl cellulose as surfactant and acetate-HCl buffer pH 4.0. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 530 nm. Methods B and C are based on redox reaction between LMFX and KMnO4 in acid and alkaline media. In indirect spectrophotometry method B the drug solution is treated with a known excess of KMnO4 in H2SO4 medium and subsequent determination of unreacted oxidant by reacting it with safronine O in the same medium at λmax = 520 nm. Direct spectrophotometry method C involves treating the alkaline solution of LMFX with KMnO4 and measuring the bluish green product at 604 nm. Method D is based on the chelation of LMFX with Zr(IV) to produce fluorescent chelate. At the optimum reaction conditions, the drug-metal chelate showed excitation maxima at 280 nm and emission maxima at 443 nm. The optimum experimental parameters for the reactions have been studied. The validity of the described procedures was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed methods were successfully applied for the determination of the selected drug in pharmaceutical preparations with good recoveries.

  1. [Indirect methods of determining the amount of cellular elements in bulk cow's milk].

    Science.gov (United States)

    Filev, F; Kabaivanov, S

    1980-01-01

    Comparative studies have been carried out to establish the practical value of three indirect methods--Whiteside, Bernburg, and the antiformin one--intended for the rapid determination of the somatic cell count in pooled cow milk. A total of 556 samples of milk from various sources have been studied. The data obtained with the use of the direct method of Prescott and Breed served as control values of the cell elements in milk. A conclusion has been made that the test after Whiteside is the most appropriate one for the rapid determination of the cell count in pooled cow milk: it gives positive results in 100 per cent of the investigated samples having a count of more than 500000 cells. The use of this method is suggested in the case of detecting farms where mastitis is a problem.

  2. A NEW RP-HPLC METHOD DEVELOPMENT AND VALIDATION OF ORLISTAT IN BULK AND PHARMACEUTICAL DOSAGE FORMS

    Directory of Open Access Journals (Sweden)

    N.Sreekanth,

    2010-07-01

    Full Text Available A simple, accurate and rapid RP-HPLC method has been developed for the estimation of Orlistat (ORL in bulk and pharmaceutical dosage forms using a C 18 column 150 x 4.6 mm i.d, 3.5m particle sizein isocratic mode, with mobile phase comprising of acetonitrile, water and phosphoric acid in the ratio of 85:15:0.5 (v/v/v. The flow rate was 1ml/min and detection was carried out by UV detector at 205nm. The retention time for ORL was found to be 3.79 min. The proposed method has permitted the quantification of ORL over linearity in the range of 6-60μg/ml and its percentage recovery was found to be 99.78-100.27%. The % RSD of intra day and inter day precision were found 0.49% and 0.57%, respectively.

  3. Spectrophotometric method for quantitative determination of triclabendazole in bulk and pharmaceutical

    Directory of Open Access Journals (Sweden)

    Alankar Shrivastava

    2011-01-01

    Full Text Available Background: Triclabendazole (TCBZ, 6-chloro-5(2-3 dichlorophenoxy-2-methyl thio-benzimidazole, an halogenated benzimidazole (BZD thiol derivative, shows high efficacy against both the immature and mature stages of Fasciola hepatica in sheep and cattle, which is a differential feature compared to other available trematodicidal drugs. As a consequence of its excellent activity against the liver fluke, it has been extensively used and this has inevitably promoted the selection of TCBZ-resistant populations, which is now a worrying problem in several areas of the world. We propose simple ultraviolet spectrophotometric method for the estimation of triclabendazole in 0.1 methanolic HCl for the estimation of the drug. Method was validated as per ICH guidelines. Materials and Methods: Spectral absorbance measurements were made on Shimadzu UV-1800 with 10 mm matched quartz cells and dilutions were made in 0.1 M methanolic HCl. Results: The LOD and LOQ of triclabendazole at 305 nm were found to be 0.068434 and 2.73×10-4 μg/ml respectively. The calibration was linear in the range of 1-10 μg/ml. Analytical parameters such as stability, selectivity, accuracy, and precision have been established for the method in Endex and Fasinex tablets and evaluated statistically to assess the application of the method. Conclusion: Method passes all parameters with in desirable limits and found to be simple, stable, sensitive, reproducible, and accurate for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving triclabendazole.

  4. Habitat Choice and Speciation

    Directory of Open Access Journals (Sweden)

    Sophie E. Webster

    2012-01-01

    Full Text Available The role of habitat choice in reproductive isolation and ecological speciation has often been overlooked, despite acknowledgement of its ability to facilitate local adaptation. It can form part of the speciation process through various evolutionary mechanisms, yet where habitat choice has been included in models of ecological speciation little thought has been given to these underlying mechanisms. Here, we propose and describe three independent criteria underlying ten different evolutionary scenarios in which habitat choice may promote or maintain local adaptation. The scenarios are the result of all possible combinations of the independent criteria, providing a conceptual framework in which to discuss examples which illustrate each scenario. These examples show that the different roles of habitat choice in ecological speciation have rarely been effectively distinguished. Making such distinctions is an important challenge for the future, allowing better experimental design, stronger inferences and more meaningful comparisons among systems. We show some of the practical difficulties involved by reviewing the current evidence for the role of habitat choice in local adaptation and reproductive isolation in the intertidal gastropod Littorina saxatilis, a model system for the study of ecological speciation, assessing whether any of the proposed scenarios can be reliably distinguished, given current research.

  5. A validated RP-HPLC method for the determination of mosapride citrate in bulk drug samples and pharmaceutical formulations.

    Science.gov (United States)

    Krishnaiah, Y S R; Murthy, T K; Sankar, D G; Satyanarayana, V

    2002-12-01

    Mosapride citrate, a selective serotonin 5-HT4 agonist, is a novel and potent gastroprokinetic drug. So far no assay procedure has been reported for the estimation of this drug either in bulk drug samples, pharmaceutical formulations or in biological samples. A rapid and sensitive high-performance liquid chromatographic method was developed for the estimation of mosapride citrate in bulk drug samples and pharmaceutical dosage forms. Risperidone was used as an internal standard (ISD). A HPLC system consisting of gradient pump, reverse phase C-18 analytical column, a variable UV-visible detector set at 274 nm and an integrator was used. The mobile phase consisted of acetonitrile: 0.02 M potassium dihydrogen phosphate buffer (pH adjusted to 4.0 with o-phosphoric acid) in the ratio of 50:50 (v/v), and was pumped at 1 ml/min at 40 degrees C. The drug and ISD were eluted at 8.10 and 2.27 min, respectively. The peak drug/ISD area ratio versus drug concentration relationship was linear (r = 0.9998). The method was validated for its linearity, precision and accuracy. The calibration curve was linear in the range of 0.5 to 30 micrograms/ml. The lower detection limit was found to be 0.23 microgram/ml. The intra- and inter-day variation was found to be less than 1% showing high precision of the assay method. The mean recovery of the drug from the solutions containing 2, 4 or 10 micrograms/ml was 101.55 +/- 0.97% indicating high accuracy of the proposed HPLC method.

  6. Formation of P3KHT:PCBM bulk-heterojunction using orthogonal solvents by ultrasonic spray method

    Science.gov (United States)

    Mahajan, Mrunal S.; Lonkar, Ganesh S.; Ghosh, Sanjay S.; Patil, Mahendra B.; Dalal, Dipak S.; Sali, Jaydeep V.

    2015-07-01

    Bulk-heterojunction (BHJ) morphologies with pure domains and sharp interfaces can lead to a more pronounced photovoltaic performance in organic solar cells. In this paper we report the formation of bulk-heterojunction of P3KHT (poly [3-(sodium-6 hexanoate) thiophene-2, 5-diyl]) and PCBM (phenyl-C61-butyric acid methyl ester) using orthogonal solvents by the ultrasonic spray method, which can lead to pure phases and sharp interfaces. P3KHT and PCBM are soluble in water and chlorobenzene respectively, which are orthogonal solvents. The modelling and simulation of the ultrasonic spray method is reported, and shows the possibility of formation of interconnecting phases of the two components in P3KHT:PCBM BHJ, formed using orthogonal solvents, if specific process parameters are chosen. The modelling and simulation also presents a way to determine optimum parameter space in an intermittent spray deposition method using orthogonal solvents. P3KHT:PCBM BHJ has been prepared using three different approaches. Significant photoluminescence quenching, suggesting efficient excitons separation before recombination has been observed in BHJ prepared by the ‘emulsion of solutions’ method. The study of the optical properties of P3KHT:PCBM BHJ suggests that the BHJ may contain bilayer type structures embedded in the BHJ morphology, which is further confirmed by complementary experiments. This new approach to preparing BHJ with pure phase domains and sharp donor/acceptor interfaces may find applications in optoelectronic devices such as organic thin-film transistors, photodetectors, organic light emitting diodes and organic solar cells.

  7. Validation of four different spectrophotometric methods for simultaneous determination of Domperidone and Ranitidine in bulk and pharmaceutical formulation

    Science.gov (United States)

    Abdel-Ghany, Maha F.; Abdel-Aziz, Omar; Mohammed, Yomna Y.

    2015-10-01

    Four simple, specific, accurate and precise spectrophotometric methods were developed and validated for simultaneous determination of Domperidone (DP) and Ranitidine Hydrochloride (RT) in bulk powder and pharmaceutical formulation. The first method was simultaneous ratio subtraction (SRS), the second was ratio subtraction (RS) coupled with zero order spectrophotometry (D0), the third was first derivative of the ratio spectra (1DD) and the fourth method was mean centering of ratio spectra (MCR). The calibration curve is linear over the concentration range of 0.5-5 and 1-45 μg mL-1 for DP and RT, respectively. The proposed spectrophotometric methods can analyze both drugs without any prior separation steps. The selectivity of the adopted methods was tested by analyzing synthetic mixtures of the investigated drugs, also in their pharmaceutical formulation. The suggested methods were validated according to International Conference of Harmonization (ICH) guidelines and the results revealed that; they were precise and reproducible. All the obtained results were statistically compared with those of the reported method, where there was no significant difference.

  8. MATHEMATICAL OPTIMIZATION METHODS TO ESTABLISH ACTIVE PHASES ON HETEROGENEOUS CATALYSIS: CASE OF BULK TRANSITION METAL SULPHIDES

    Directory of Open Access Journals (Sweden)

    Iván Machín

    2015-03-01

    Full Text Available This paper presents a set of procedures based on mathematical optimization methods to establish optimal active sulphide phases with higher HDS activity. This paper proposes a list of active phases as a guide for orienting the experimental work in the search of new catalysts that permit optimize the HDS process. Studies in this paper establish Co-S, Cr-S, Nb-S and Ni-S systems have the greatest potential to improve HDS activity.

  9. Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

    Science.gov (United States)

    Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

    2012-12-21

    Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

  10. Speciation and bifurcations.

    Science.gov (United States)

    Volkenstein, M V; Livshits, M A

    1989-01-01

    The interrelations of physics and biology are discussed. It is shown that Darwin can be considered as one of the founders of the important field of contemporary physics called physics of dissipative structures or synergetics. The theories of gradual and punctual evolution are presented. The contradiction between these theories can be solved on the basis of molecular theory of evolution and on the basis of the phenomenological physical treatment. The general physical properties of living systems, considered as open systems being far from equilibrium, are listed and simple non-linear mathematical models describing gradual and punctual speciation are suggested. The usual pictures which present these two kinds of speciation can possess physico-mathematical sense. Punctuated speciation means bifurcation, a kind of non-equilibrium phase transition.

  11. Bulk crystals of L-Histidinium dihydrogen phosphate orthophosphoric acid grown by Sankaranarayanan-Ramasamy method

    Science.gov (United States)

    Ittyachan, Reena; Arunkumar, A.

    2017-01-01

    L-Histidinium dihydrogen phosphate orthophosphoric acid (LHDP) crystal of length 80 mm long and 20 mm diameter has been grown from aqueous solution along c-axis using Sankaranarayanan-Ramasamy method. The unit cell parameters were confirmed by single crystal X-ray diffraction analysis and it belongs to orthorhombic system. The UV-vis-NIR spectrum showed that the grown crystal is transparent in the entire visible region. The lower optical cut-off wavelength for this crystal was observed at 240 nm. Fluorescence studies were carried out in range of 200-700 nm. SHG efficiency was analyzed using Kurtz-Perry powder technique.

  12. Spectrophotometric method for estimation of amiloride in bulk and tablet dosage form

    Directory of Open Access Journals (Sweden)

    Aitha Vijaya Lakshmi

    2015-01-01

    Full Text Available Introduction: Amiloride chemically, 3,5-diamino-6-chloro-N-(diaminomethylene pyrazine-2-carboxamide. It is used in the management of congestive heart failure, available as Amifru tab, Amimide. It causes adverse effects like Nausea, diarrhea and dizziness. Materials: 0.1 N Hydrochloric acid, 0.1 N Sodium hydroxide and 1 mg/ml amiloride drug solution were required. Spectral and absorbance measurements were made using ELICO UV-160 double beam Spectrophotometer. Method: Amiloride drug solution concentration range of 25 to 125ug/ml in 0.1N HCl medium was scanned over the wave length range of 235-320 against blank prepared in 0.1N NaOH solution. Two wavelengths are selected one at positive peak 245 nm and another at negative peak 290 nm, the amplitude is calculated from these values. Results and Discussion: The sum of the absolute values at these wavelengths is called amplitude. The amplitude is proportional to the amount of drug. High accuracy, reproducibility and low t-values were reported from the calibration curve plotted with the amplitude verses amount of drug. So the proposed method is simple, less time consuming and it can be successfully adopted for the estimation of amiloride.

  13. Efficient Execution Methods of Pivoting for Bulk Extraction of Entity-Attribute-Value-Modeled Data.

    Science.gov (United States)

    Luo, Gang; Frey, Lewis J

    2016-03-01

    Entity-attribute-value (EAV) tables are widely used to store data in electronic medical records and clinical study data management systems. Before they can be used by various analytical (e.g., data mining and machine learning) programs, EAV-modeled data usually must be transformed into conventional relational table format through pivot operations. This time-consuming and resource-intensive process is often performed repeatedly on a regular basis, e.g., to provide a daily refresh of the content in a clinical data warehouse. Thus, it would be beneficial to make pivot operations as efficient as possible. In this paper, we present three techniques for improving the efficiency of pivot operations: 1) filtering out EAV tuples related to unneeded clinical parameters early on; 2) supporting pivoting across multiple EAV tables; and 3) conducting multi-query optimization. We demonstrate the effectiveness of our techniques through implementation. We show that our optimized execution method of pivoting using these techniques significantly outperforms the current basic execution method of pivoting. Our techniques can be used to build a data extraction tool to simplify the specification of and improve the efficiency of extracting data from the EAV tables in electronic medical records and clinical study data management systems.

  14. A Validated Enantioselective HPLC Method for Determination of Ibuprofen Enantiomers in Bulk and Tablet Dosage Form.

    Science.gov (United States)

    2016-04-19

    A new chiral reversed-phase (RP)-HPLC method with UV detection was developed. Enantioselective resolution of ibuprofen (IBP) was achieved using (3R,4S)-4-(3,5-dinitrobenzamido)-3-(3-(trioxysilyl)- propyl)-1,2,3,4-tetrahydro-phenanthrene [(R,R)-Whelk-O2] chiral stationary phase (4.6 mm id × 250 mm, 10 μm) with a mobile phase composed of ethanol-water (30 + 70, v/v) containing 100 mM ammonium acetate at a flow rate of 1.3 mL/min using diode array detector at λ 220 nm. Calibration curves were linear over the concentration range of 20-180 μg/mL for both IBP enantiomers. Mean % recoveries ±SD of 99.74 ± 1.73 and 99.60 ± 0.93 were obtained for dexibuprofen (dex-IBP) and levoibuprofen (levo-IBP), respectively. Intra- and interday precision calculated as RSD, % were not more than 1.66% for dex-IBP and 1.93% for levo-IBP. The detection limits were 2.09 and 2.06 μg/mL for dex-IBP and levo-IBP, respectively. The method was successfully applied for the determination of dex-IBP in tablet dosage form.

  15. How does climate influence speciation?

    Science.gov (United States)

    Hua, Xia; Wiens, John J

    2013-07-01

    Variation in climatic conditions over space and time is thought to be an important driver of speciation. However, the role of climate has not been explored in the theoretical literature on speciation, and the theory underlying empirical studies of climate and speciation has come largely from informal, verbal models. In this study, we develop a quantitative model to test a relatively new but theoretically untested model of speciation (speciation via niche conservatism) and to examine the climatic conditions under which speciation via niche conservatism and speciation via niche divergence are most plausible. Our results have three broad implications for the study of speciation: (1) ecological similarity over time (niche conservatism) can be an important part of speciation, despite the traditional emphasis on ecological divergence, (2) long-term directional climate change promotes speciation via niche conservatism for species with low climatic-niche lability, whereas climatic oscillations promote speciation via niche divergence for species with high climatic-niche lability, and (3) population extinction can be a key component of speciation.

  16. Inference of Gene Flow in the Process of Speciation: An Efficient Maximum-Likelihood Method for the Isolation-with-Initial-Migration Model

    Science.gov (United States)

    Costa, Rui J.; Wilkinson-Herbots, Hilde

    2017-01-01

    The isolation-with-migration (IM) model is commonly used to make inferences about gene flow during speciation, using polymorphism data. However, it has been reported that the parameter estimates obtained by fitting the IM model are very sensitive to the model’s assumptions—including the assumption of constant gene flow until the present. This article is concerned with the isolation-with-initial-migration (IIM) model, which drops precisely this assumption. In the IIM model, one ancestral population divides into two descendant subpopulations, between which there is an initial period of gene flow and a subsequent period of isolation. We derive a very fast method of fitting an extended version of the IIM model, which also allows for asymmetric gene flow and unequal population sizes. This is a maximum-likelihood method, applicable to data on the number of segregating sites between pairs of DNA sequences from a large number of independent loci. In addition to obtaining parameter estimates, our method can also be used, by means of likelihood-ratio tests, to distinguish between alternative models representing the following divergence scenarios: (a) divergence with potentially asymmetric gene flow until the present, (b) divergence with potentially asymmetric gene flow until some point in the past and in isolation since then, and (c) divergence in complete isolation. We illustrate the procedure on pairs of Drosophila sequences from ∼30,000 loci. The computing time needed to fit the most complex version of the model to this data set is only a couple of minutes. The R code to fit the IIM model can be found in the supplementary files of this article. PMID:28193727

  17. Electrical and Optical Properties of Bulk ZnO Single Crystal Grown by Flux Bridgman Method

    Institute of Scientific and Technical Information of China (English)

    LI Xin-Hua; XU Jia-Yue; JIN Min; SHEN Hui; LI Xiao-Min

    2006-01-01

    Zinc oxide (ZnO) single crystals are grown by the modified vertical Bridgman method using a PbF2 flux. Themaximum size of the as-grown ZnO crystal is about φ25 mm× 5mm. The transmittance of the as-grown ZnOcrystal is more than 70% in the range of 600-800nm and the optical band gap is estimated to be 3.21 eV. Thephotoluminescence spectrum indicates that the as-grown ZnO crystal has a very low concentration of nativedefects and is much closed to its stoichiometry. The electrical measurement exhibits that the ZnO crystal haslow electrical resistivity of 0.02394Ωcm-1 and a high carrier concentration of 2.10 × 1018 cm-3

  18. Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Isao Tanaka

    2009-01-01

    Full Text Available Copper orthophosphate, Cu3(PO42, and cyclo-tetraphosphates, Cu2P4O12, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD and Fourier transform infrared (FT-IR spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied.

  19. Development of Stability Indicating LC Method for the Estimation of Tolperisone in Bulk and Pharmaceutical Dosage Form

    Directory of Open Access Journals (Sweden)

    U. K. Chhalotiya

    2013-01-01

    Full Text Available A rapid, specific, and sensitive reverse phase high performance liquid chromatographic method has been developed and validated for analysis of tolperisone in both bulk and pharmaceutical dosage form. The HPLC method was performed with a reversed phase C18 SunFire column (250 mm × 4.6 mm i.d., 5 mm particle size, detection at 261 nm and a mixture of methanol, water and pH 7.5 adjusted by use of 1% solution of triethylamine (60 : 40 as mobile phase. The flow rate was 1.0 mL min−1 and effluents were monitored at 261 nm. The retention time of tolperisone was 4.8 min. Tolperisone was subjected to acid and alkali hydrolysis, chemical oxidation, wet hydrolysis, dry heat degradation, and sunlight degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of tolperisone in tablet dosage forms.

  20. Two methods of tuning threshold voltage of bulk FinFETs with replacement high-k metal-gate stacks

    Science.gov (United States)

    Xu, Miao; Zhu, Huilong; Zhang, Yanbo; Xu, Qiuxia; Zhang, Yongkui; Qin, Changliang; Zhang, Qingzhu; Yin, Huaxiang; Xu, Hao; Chen, Shuai; Luo, Jun; Li, Chunlong; Zhao, Chao; Ye, Tianchun

    2017-03-01

    In this work, we propose two threshold voltage (VTH) tuning methods for bulk FinFETs with replacement high-k metal gate. The first method is to perform a vertical implantation into fin structure after dummy gate removal, self-aligned forming halo & punch through stop pocket (halo & PTSP) doping profile. The second method is to execute P+/BF2+ ion implantations into the single common work function (WF) layer in N-/P-FinFETs, respectively. These two methods have been investigated by TCAD simulations and MOS-capacitor experiments respectively, and then integrated into FinFET fabrication successfully. Experimental results show that the halo & PTSP doping profile can reduce VTH roll off and total variation. With P+/BF2+ doped WF layer, the VTH-sat shift -0.43 V/+1.26 V for N-FinFETs and -0.75 V/+0.11 V for P-FinFETs, respectively, with gate length of 500 nm. The proposed two methods are simple and effective for FinFET VTH tuning, and have potential for future application of massive production.

  1. Novel LC Method Development and Validation for Simultaneous Determination of Montelukast and Doxofylline in Bulk and Pharmaceutical Dosage Forms

    Directory of Open Access Journals (Sweden)

    Gadapa Nirupa

    2013-01-01

    Full Text Available A novel rapid HPLC method was developed for simultaneous determination of montelukast and doxofylline in bulk and pharmaceutical dosage forms. Development of an analytical method for simultaneous estimation of drugs requires a lot of efforts and of course it is a challenging task. The method was developed by using C18 (150 mm×4.6 mm, 5 μm column; mobile phase consisting of methanol and phosphate buffer at pH 4.5; the flow rate of 1.0 mL/min and ultraviolet detection at 280 nm. Both drugs were sufficiently resolved having retention time of 4.7 min and 1.9 min for montelukast and doxofylline, respectively. The method was validated as per ICH Guidelines for various parameters like precision, linearity, accuracy, ruggedness, and robustness. The validated method was applied to the commercially available pharmaceutical dosage form and obtained the desired result.

  2. Selenium Speciation and Management in Wet FGD Systems

    Energy Technology Data Exchange (ETDEWEB)

    Searcy, K; Richardson, M; Blythe, G; Wallschlaeger, D; Chu, P; Dene, C

    2012-02-29

    rapidly than it sorbs to ferric solids. Though it was not possible to demonstrate a decrease in selenium concentrations to levels below the project'ale testing were evident at the pilot scale. Specifically, reducing oxidation air rate and ORP tends to either retain selenium as selenite in the liquor or shift selenium phase partitioning to the solid phase. Oxidation air flow rate control may be one option for managing selenium behavior in FGD scrubbers. Units that cycle load widely may find it more difficult to impact ORP conditions with oxidation air flow rate control alone. Because decreasing oxidation air rates to the reaction tank showed that all new selenium reported to the solids, the addition of ferric chloride to the pilot scrubber could not show further improvements in selenium behavior. Ferric chloride addition did shift mercury to the slurry solids, specifically to the fine particles. Several competing pathways may govern the reporting of selenium to the slurry solids: co-precipitation with gypsum into the bulk solids and sorption or co-precipitation with iron into the fine particles. Simultaneous measurement of selenium and mercury behavior suggests a holistic management strategy is best to optimize the fate of both of these elements in FGD waters. Work conducted under this project evaluated sample handling and analytical methods for selenium speciation in FGD waters. Three analytical techniques and several preservation methods were employed. Measurements of selenium speciation over time indicated that for accurate selenium speciation, it is best to conduct measurements on unpreserved, filtered samples as soon after sampling as possible. The capital and operating costs for two selenium management strategies were considered: ferric chloride addition and oxidation air flow rate control. For ferric chloride addition, as might be expected the reagent makeup costs dominate the overall costs, and range from 0.22 to 0.29 mills/kWh. For oxidation air flow rate

  3. Bulk crystal growth of Mg{sub 2}Si by the vertical Bridgman method

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaga, M.; Iida, T.; Noda, M.; Endo, T.; Takanashi, Y

    2004-08-02

    Mg{sub 2}Si were grown by the vertical Bridgman (VB) method in crucibles made of chemical vapor deposition (CVD) pyrolytic graphite (PG) in order to minimize the reaction and sticking of molten Mg-Si during growth. Congruent crystallization was derived from a stoichiometric melt of Mg{sub 2}Si, and incongruent crystallization was derived from nonstoichiometric melts having Mg/Si ratios of 85:15, 70:30 and 60:40. Grown samples were characterized by X-ray diffraction and electron-probe microanalysis, and their power factors were calculated from the Seebeck coefficients and electrical conductivities measured from room temperature to 773 K. The grown crystals were single-crystal-like and had high Seebeck coefficients at the temperatures from 500 to 773 K. A sample derived from a stoichiometric melt had a Seebeck coefficient of -470 {mu}V/K and the highest power factor, 7.8x10{sup -6} W/cm K{sup 2} at 373 K, was calculated for the sample derived from a melt with an Mg/Si ratio of 70:30.

  4. Fabrication and characterization of iron pnictide wires and bulk materials through the powder-in-tube method

    Science.gov (United States)

    Ma, Yanwei; Gao, Zhaoshun; Qi, Yanpeng; Zhang, Xianping; Wang, Lei; Zhang, Zhiyu; Wang, Dongliang

    2009-05-01

    The recent discovery of superconductivity in the iron-based superconductors with very high upper critical fields presents a new possibility for practical applications, but fabricating fine-wire is a challenge because of mechanically hard and brittle powders and the toxicity and volatility of arsenic. In this paper, we report the synthesis and the physical characterization of iron pnictide wires and bulks prepared by the powder-in-tube method (PIT). A new class of high- Tc iron pnictide composite wires, such as LaFeAsO 1-xF x, SmFeAsO 1-xF x and Sr 1-xK xFeAs, has been fabricated by the in situ PIT technique using Fe, Ta and Nb tubes. Microscopy and X-ray analysis show that the superconducting core is continuous, and retains phase composition after wire drawing and heat treatment. Furthermore, the wires exhibit a very weak Jc-field dependence behavior even at high temperatures. The upper critical field Hc2(0) value can exceed 100 T, surpassing those of MgB 2 and all the low temperature superconductors and indicating a strong potential for applications requiring very high field. These results demonstrate the feasibility of producing superconducting pnictide composite wire. We also applied the one-step PIT method to synthesize the iron-based bulks, due to its convenience and safety. In fact, by using this technique, we have successfully discovered superconductivity at 35 K and 15 K in Eu 0.7Na 0.3Fe 2As 2 and SmCoFeAsO compounds, respectively. These clearly suggest that the one-step PIT technique is unique and versatile and hence can be tailored easily for other rare earth derivatives of novel iron-based superconductors.

  5. Fabrication and characterization of iron pnictide wires and bulk materials through the powder-in-tube method

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yanwei, E-mail: ywma@mail.iee.ac.c [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China); Gao Zhaoshun; Qi Yanpeng; Zhang Xianping; Wang Lei; Zhang Zhiyu; Wang Dongliang [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China)

    2009-05-01

    The recent discovery of superconductivity in the iron-based superconductors with very high upper critical fields presents a new possibility for practical applications, but fabricating fine-wire is a challenge because of mechanically hard and brittle powders and the toxicity and volatility of arsenic. In this paper, we report the synthesis and the physical characterization of iron pnictide wires and bulks prepared by the powder-in-tube method (PIT). A new class of high-T{sub c} iron pnictide composite wires, such as LaFeAsO{sub 1-x}F{sub x}, SmFeAsO{sub 1-x}F{sub x} and Sr{sub 1-x}K{sub x}FeAs, has been fabricated by the in situ PIT technique using Fe, Ta and Nb tubes. Microscopy and X-ray analysis show that the superconducting core is continuous, and retains phase composition after wire drawing and heat treatment. Furthermore, the wires exhibit a very weak J{sub c}-field dependence behavior even at high temperatures. The upper critical field H{sub c2}(0) value can exceed 100 T, surpassing those of MgB{sub 2} and all the low temperature superconductors and indicating a strong potential for applications requiring very high field. These results demonstrate the feasibility of producing superconducting pnictide composite wire. We also applied the one-step PIT method to synthesize the iron-based bulks, due to its convenience and safety. In fact, by using this technique, we have successfully discovered superconductivity at 35 K and 15 K in Eu{sub 0.7}Na{sub 0.3}Fe{sub 2}As{sub 2} and SmCoFeAsO compounds, respectively. These clearly suggest that the one-step PIT technique is unique and versatile and hence can be tailored easily for other rare earth derivatives of novel iron-based superconductors.

  6. Development of a Simple RP-HPLC-UV Method for Determination of Azithromycin in Bulk and Pharmaceutical Dosage forms as an Alternative to the USP Method

    Science.gov (United States)

    Ghari, Tayebeh; Kobarfard, Farzad; Mortazavi, Seyed Alireza

    2013-01-01

    The present study was designed to develop a simple, validated liquid chromatographic method for the analysis of azithromycin in bulk and pharmaceutical dosage forms using ultraviolet detector. The best stationary phase was determined as C18 column, 5 μm, 250 mm × 4.6 mm. Mobile phase was optimized to obtain a fast and selective separation of the drug. Flow rate was 1.5 mL/min, Wavelength was set at 210 nm and the volume of each injection was 500 μL. An isocratic methanol/buffer mobile phase at the ratio of 90:10 v/v gave the best separation and resolution. The proposed method was accurate, precise, sensitive, and linear over a wide range of concentration of azithromycin. The developed method has the advantage of using UV detector compared to the USP method in which electrochemical detector has been used. The validated method was successfully applied to the determination of azithromycin in bulk and pharmaceutical dosage forms. PMID:24250672

  7. Ultrafiltration technique in conjunction with competing ligand exchange method for Ni–humics speciation in aquatic environment

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Boissel, M.; Reuillon, A.; Babu, P.V.R.; Parthiban, G.

    The combination of ultrafiltration technique with competing ligand exchange method provides a better understanding of interactions between Ni and different molecular weight fractions of humic acid (HA) at varying pH in aquatic environment...

  8. Method of aeration disinfecting and drying grain in bulk and pretreating seeds and a transverse blow silo grain dryer therefor

    Science.gov (United States)

    Danchenko, Vitaliy G.; Noyes, Ronald T.; Potapovych, Larysa P.

    2012-02-28

    Aeration drying and disinfecting grain crops in bulk and pretreating seeds includes passing through a bulk of grain crops and seeds disinfecting and drying agents including an ozone and air mixture and surrounding air, subdividing the disinfecting and drying agents into a plurality of streams spaced from one another in a vertical direction, and passing the streams at different heights through levels located at corresponding heights of the bulk of grain crops and seeds transversely in a substantially horizontal direction.

  9. Development and validation of a simple spectrophotometric method for the determination of methyldopa in both bulk and marketed dosage formulations

    Directory of Open Access Journals (Sweden)

    Paulo Roberto da Silva Ribeiro

    2014-09-01

    Full Text Available A simple, precise, sensitive, rapid, specific and economical spectrophotometric method was developed to determine methyldopa (MTD content in bulk and pharmaceutical dosage formulations. The proposed method was based on the formation of a colored product from the nitrosation reaction of MTD with sodium nitrite in an acid medium. The resultant nitroso derivative species reacts further with sodium hydroxide and is converted it into a more stable compound. This yellow nitrosation product exhibited an absorption maximum at 430 nm. Beer's Law was obeyed in a concentration range of 6.37 to 82.81 μg mL-1 MTD with an excellent coefficient of determination (R2 = 0.9998. No interference was observed from common excipients in formulations. The results showed the method to be simple, accurate and readily applied for the determination of MTD in pure form and in pharmaceutical preparations. The analytical results obtained for these products using the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure at a 95% confidence level.

  10. DEVELOPMENT AND VALIDATION OF A NEW HPLC METHOD FOR THE ESTIMATION OF AZITHROMYCIN IN BULK AND TABLET DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Irin Dewan*, T. Amin , Md. F. Hossain , M. Hasan , S. F. Chowdhury , M. Gazi and S.M. Ashraful Islam

    2013-01-01

    Full Text Available A simple, reproducible and efficient reversed phase high performance liquid chromatographic (RP-HPLC method has been developed for quantitative determination of azithromycin in drug substance. The separations were carried out on a Xterra C18 column (150 ×4.6 mm; 5µ with UV detection at 215 nm. The mobile phase consisting of acetonitrile and phosphate buffer (pH adjusted to 7.5 in a ratio of 50:50 v/v. The injection volume was 50 µl and flow rate was 1.0 mL/min. The linear dynamic response was found to be in the concentration range of 300µg-700 µg/mL and coefficient of correlation was found to be 0.998. The %RSD value was below 2.0 for intraday and interday precision indicated that the method was highly precise. The percentage recovery value was higher than 100 %, indicating the accuracy of the method and absence of interference of the excipients present in the tablet formulation. The proposed method was simple, economic, accurate, precise and reproducible and hence can be applied for routine quality control analysis of azithromycin in bulk and dosage form.

  11. FIRST ORDER DERIVATIVE SPECTROPHOTOMETRIC METHOD FOR SIMULTANEOUS ESTIMATION OF TELMISARTAN AND CHLORTHALIDONE IN BULK AND PHARMACEUTICAL DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Parmar Kreny E.

    2013-03-01

    Full Text Available A simple, precise, and accurate method was developed for the estimation of Telmisartan (TEL and Chlorthalidone (CHL in bulk and pharmaceutical dosage form using first order derivative spectrophotometry. Wavelength selected for quantitation were 264.85nm for Telmisartan (zero crossing point of Chlorthalidone and 222.38nm for Chlorthalidone(zero crossing point of Telmisartan. The method was validated with respect to linearity, accuracy, precision, limit of detection and limit of quantitation in accordance with the International Conference on Harmonisation (ICH guidelines. Linearity was observed in concentration range of 8-48 µg/ml for Telmisartan and 2.5-15 µg/ml for Chlorthalidone. The limit of detection and limit of quantitation were found to be 0.234µg/ml and 0.712 µg/ml for Telmisartan and 0.102 µg/ml and 0.309 µg/ml for Chlorthalidone. The percentage recovery of Telmisartan and Chlorthalidone was found to be 99.26% and 99.36% respectively. The % R.S.D. values for intra-day and inter-day precision study were <1.0%, confirming that the method was sufficiently precise. The method can be successfully employed for the simultaneous estimation of Telmisartan and Chlorthalidone in pharmaceutical formulations.

  12. Magnetic Forces Investigation of Bulk HTS over Permanent Magnetic Guideway under Different Lateral Offset with 3D-Model Numerical Method

    Directory of Open Access Journals (Sweden)

    Yiyun Lu

    2012-01-01

    Full Text Available Magnetic forces of a cylinder shape bulk high-temperature superconductor (HTS over a permanent magnet guideway (PMG are studied mathematically. One cylindrical bulk HTS with a diameter of 30 mm and 15 mm in height is used. Two types of PMG are employed for external magnetic fields consideration. The relationship of magnetic forces of bulk HTS under different lateral offsets over PMG is studied with 3D-model finite element method (FEM. The calculation results show that the maximum magnetic levitation force of bulk HTS over PMG is tightly related to the applied magnetic field distribution. For the symmetrical PMG, the maximum magnetic levitation force decreases linearly with the increase of lateral offset of the bulk sample. For the Halbach PMG, when lateral offset changes from 0 mm to 25 mm, the maximum magnetic levitation force increases with the increase of lateral offset of the bulk HTS. When the lateral offset exceeds the center of the Halbach by 25 mm, the maximum levitation force decreases rapidly with the increase of the lateral offset of the bulk sample.

  13. A novel method for the quantification, characterisation and speciation of silver nanoparticles in earthworms exposed in soil

    NARCIS (Netherlands)

    Makama, S.I.; Peters, R.J.B.; Undas, A.K.; Brink, van den N.W.

    2015-01-01

    Currently, metal engineered nanoparticles (ENPs) in tissues are generally quantified based on total concentrations after acid digestion of samples. Electron microscopy has also been used for non-quantitative characterisation of NPs in situ, and can be enhanced with tissue-processing methods that can

  14. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); Moricz, Agnes M. [L. Eoetvoes University, Department of Chemical Technology and Environmental Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Kroepfl, Krisztina [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Szikora, Szilvia [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Parra, Lue Meru Marco [Universidad Centro-occidental Lisandro Alvarado, Decanato de Agronomia, Departamento de Quimica y Suelos Unidad de Analisis Instrumental, Apartado Postal 4076, Cabudare 3023 (Venezuela); Zaray, Gyula [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary) and Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary) and L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods.

  15. Searching for speciation genes

    DEFF Research Database (Denmark)

    Holt, Benjamin George; Côté, Isabelle M; Emerson, Brent C

    2011-01-01

    Closely related species that show clear phenotypic divergence, but without obvious geographic barriers, can provide opportunities to study how diversification can occur when opportunities for allopatric speciation are limited. We examined genetic divergence in the coral reef fish genus Hypoplectr...... evidence for genes that may be associated with colour morphotype in the genus Hypoplectrus....

  16. Capillary electrophoresis method for speciation of iron (II) and iron (III) in pharmaceuticals by dual precapillary complexation.

    Science.gov (United States)

    Gotti, Roberto; Fiori, Jessica; Liverani, Lino; Spelta, Franco

    2015-07-20

    Pharmaceutical iron sucrose is an iron (III) replacement for the treatment of iron deficiency anemia in patients with chronic kidney disease. The drug product (injection) is a colloidal solution of ferric hydroxide in complex with sucrose, containing 20 mg/mL elemental iron; according to United States pharmacopoeia (USP), the limit of iron (II) is 0.4% w/v. A selective CE method for the simultaneous determination of iron (III) and its potential impurity iron (II), was developed by applying a dual precapillary complexation. In particular, 1,10-phenanthroline and 1,2-diaminocyclohexanetetraacetic acid were used for complexation of iron (II) and iron (III), respectively. Sample preparation was optimized to achieve mineralization of pharmaceuticals using HCl 6 M, by avoiding perturbation of the oxidation status of both iron species. Simple CZE conditions, involving a 60 mM (pH 9.3) tetraborate buffer at the constant voltage of 25 KV and 25°C, allowed fast separation of iron (II) and iron (III) complexes that were detected at 265 nm. Sensitivity for iron (II) determination was found to be 4.80 μM (LOQ) corresponding to 0.15% w/w with respect to the total iron test level. The method was validated by following International Conference on Harmonization guidelines for specificity, linearity, precision, accuracy, and robustness and it was applied to real pharmaceutical samples. The obtained results suggested that the method can be a useful alternative to the official USP and British pharmacopoeia polarographic method.

  17. A new spectrofluorometric method for the determination of total arsenic in sediments and its application to kinetic speciation

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; RaghunadhBabu, P.V.; Sarma, V.V.

    , 259 (2002) 32. I. Bodek, W.J. Lyman, W.F. Reehl, D.H. Rosenblatt, Environmental Inorganic Chemistry: Properties, Processes and Estimation Methods, Pergamon Press, USA (1998). 33. P.L. Smedley, Kinniburgh D.G. Sources and behaviour of arsenic...-metal or metalloid. As can be found in different oxidation states in nature and each of the forms vary in toxicity and occurrence. The concentration of this carcinogenic metalloid is increasing in different environmental compartments mainly because...

  18. Strategy for the mapping of interactive genes using bulked segregant analysis method and Mapmaker/Exp software

    Institute of Scientific and Technical Information of China (English)

    WU Weiren; HUANG Biguang

    2006-01-01

    A qualitative trait is usually controlled by a single gene, but it may be sometimes controlled by two or even more genes. This phenomenon is called gene interaction. Rapidly searching for linked molecular markers via bulked segregant analysis (BSA)and then constructing regional linkage map with Mapmaker/Exp has become a common approach to mapping single major genes. However, methods and computer programs developed for mapping single major genes cannot be simply applied to interactive genes because the genetic patterns of gene interactions are quite different from that of single-gene inheritance. Up to now, experimental methods for quickly screening molecular markers linked to interactive genes and statistical methods and corresponding computer softwares for simultaneously analyzing the linkage relationships of multiple molecular markers to an interactive gene have not been available. To solve this problem, in this paper, we propose a strategy for mapping interactive genes using BSA and Mapmaker/Exp. We demonstrate that Mapmaker/Exp' strategy using F2 generation (in a few cases, F3 generation is also needed). As BSA and Mapmaker/Exp have been broadly used in gene mapping studies and are well known by many researchers, the strategies proposed in this paper will be useful for practical researches.

  19. RP-HPLC Method for Simultaneous Estimation of Cefepime Hydrochloride and Tazobactam Sodium in Bulk and Pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Sagar R. Tamboli

    2013-01-01

    Full Text Available A precise, accurate, sensitive and robust RP-HPLC method was developed for cefepime hydrochloride and tazobactam sodium in bulk and pharmaceutical formulation. Chromatographic separation was achieved on PrincetonSPHER-100 C-18 column (250 mm × 4.6 mm i.d., 5 µm at ambient temperature. A binary mobile phase consisting of 25 mM potassium dihydrogen phosphate buffer, pH 6.2 and acetonitrile (94 : 6, v/v was delivered through a column at a flow rate of 1 mL/min. Measurement was performed at a wavelength 210 nm. The method was linear over the concentration range of 4–24 µg/mL ( for cefepime and 0.5–3.0 µg/mL ( for tazobactam. The percentage content found for cefepime was 101.12 ± 0.49 and for tazobactam was 101.33 ± 1.17 in the pharmaceutical formulation. The method was validated for linearity, precision, accuracy, sensitivity and robustness as per ICH Q2 (R1 guideline.

  20. Development of a validated liquid chromatographic method for determination of related substances of telmisartan in bulk drugs and formulations.

    Science.gov (United States)

    Rao, R Nageswara; Guru Prasad, K; Gangu Naidu, Ch; Maurya, Pawan K

    2011-11-01

    A simple and rapid reversed phase liquid chromatographic method for separation and determination of the related substances of telmisartan (TLM) was developed and validated. The chromatographic separation was achieved on Lichrospher RP-18 column (250 × 4.6 mm, 5 μm), using 20 mM ammonium acetate containing 0.1% (v/v) triethylamine (pH adjusted to 3.0 with trifluoroacetic acid) and acetonitrile as mobile phase at 25°C. The detection was performed at 254 nm. The method was validated and found to be robust, precise, specific and linear between 0.37 and 500 μg/mL. The limits of detection and quantification of telmisartan were 0.11 and 0.37 μg/mL, respectively. The method was successfully applied to quantify related substances and assay of TLM in bulk drugs and commercial tablets. The related substances relate to a novel synthetic route and different from those A-H impurities reported by European Pharmacopeia.

  1. RP-HPLC-DAD method for the determination of phenylepherine, paracetamol, caffeine and chlorpheniramine in bulk and marketed formulation

    Directory of Open Access Journals (Sweden)

    A.P. Dewani

    2014-11-01

    Full Text Available A simple, specific and accurate isocratic RP-HPLC-DAD method was developed for the simultaneous determination of phenylephrine, paracetamol, caffeine and chlorpheniramine in bulk and tablet dosage form. The four contents are present in variable concentrations and have variable chromatographic behavior making the process of analysis very difficult. For present studies a reversed-phase C-18 column (150 mm × 4.5 mm i.d., particle size 5 μm with mobile phase consisting of acetonitrile, methanol and 10 Mm phosphate buffer 16:22:62 (v/v (pH of buffer 2.5 ± 0.02, adjusted with ortho phosphoric acid was used. The flow rate was 1.0 ml/min and eluents were monitored at 280 nm. The mean retention times of phenylephrine, paracetamol, caffeine and chlorpheniramine were found to be 1.8, 3.1, 5.2 and 10.9 min, respectively. The method was validated in terms of linearity, range, specificity, accuracy, precision and robustness. The proposed method was successfully applied to the estimation of phenylephrine, paracetamol, caffeine and chlorpheniramine in combined tablet dosage form.

  2. Development of a validated stability-indicating HPTLC method for rufinamide in bulk and its pharmaceutical dosage form.

    Science.gov (United States)

    Patel, Apexa; Patwari, Arpit; Suhagia, Bhanubhai

    2014-01-01

    A sensitive, selective, precise and stability indicating a high-performance thin layer chromatographic method for the analysis of rufinamide (Rf) in bulk drug and its formulations was developed and validated. The method employed thin layer chromatography aluminum plates precoated with silica gel 60 F254 as the stationary phase. The solvent system consisted of chloroform : methanol : glacial acetic acid (9 : 1 : 0.1 v/v/v). This system was found to give compact spots for Rf (Rf value of 0.68 ± 0.02). Rf was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. Also, the degraded products were well separated from the pure drug. Densitometric analysis of Rf was carried out in the absorbance mode at 210 nm, which is wavelength maxima for the degradant. The linear regression data for the calibration plots showed a good linear relationship with an r(2) of 0.9989 in the concentration range of 1,000-3,500 ng. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 196.59 and 595.74 ng spot(-1), respectively. The drug undergoes degradation under acidic and basic conditions. All the peaks of degraded products were resolved from the standard drug with significantly different Rf values.

  3. Speciation of arsenic and mercury in feed: why and how?

    Directory of Open Access Journals (Sweden)

    Hedegaard, RV.

    2011-01-01

    Full Text Available The understanding of the mechanisms of biological activities and biotransformation of trace elements such as arsenic and mercury has improved during recent years with the help of chemical speciation studies. However, the most important practical application of elemental speciation is in the area of toxicology. Toxicological knowledge on the individual trace element species can lead to more specific legislation of hazardous substances found in feed. Examples here are arsenic, where the inorganic forms are the most toxic, and mercury, where the organic form methylmercury is more toxic than inorganic mercury. In the present paper an overview of the current knowledge on arsenic and mercury speciation in feed and analytical methodologies for arsenic and mercury speciation analysis are given. Additionally the current status and expected future developments within legislation for trace element speciation in feed as well as initiatives for the establishment of standardized methods for determination of inorganic arsenic and methylmercury are presented.

  4. Stability indicating RP-HPLC method for the estimation of Decitabine in bulk drug and lipid based Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yub Raj Neupane

    2014-07-01

    Full Text Available The aim of our present work was to develop and validate a reverse phase high-performance liquid chromatography (RP-HPLC method for the determination of Decitabine (DCB. The developed method was further applied to observe the degradation of DCB under various stress conditions. Methods: Chromatographic separation was achieved on C18, 250 × 4.6 mm, particle size 5 μm, Agilent column, using ammonium acetate (0.01M as mobile phase with flow rate of 1mL/min and injection volume was 20 μL. Quantification was carried out with UV detector at 230 nm with a linear calibration curve in the concentration range of 10–100 μg/mL based on peak area. Thus, developed method was validated for linearity, accuracy, precision, and robustness. Results: Linearity was found to be in the range between 10–100 μg/mL with a significantly higher value of correlation coefficient r2 = 0.9994. The limits of detection (LOD and the limits of quantification (LOQ were found to be 1.92μg/mL and 5.82 μg/mL respectively. Moreover, validated method was applied to study the degradation profile of DCB under various stress degradation conditions. Examination of different stress conditions on degradation of DCB showed that its degradation was highly susceptible to oxidative condition as 31.24% of drug was degraded. In acidic and alkaline conditions, the drug was degraded by 21.03% and 12.16% respectively, while thermal and photolytic condition causes least degradation, i.e. 0.21% and 0.3% respectively. Conclusion: The proposed method was found to be sensitive, specific and was successfully applied for the estimation of DCB in bulk drug, and lipid based nanoparticles.

  5. A Validated RP-HPLC Method for the Determination of Recombinant Human Insulin in Bulk and Pharmaceutical Dosage Form

    Directory of Open Access Journals (Sweden)

    B. A. Moussa

    2010-01-01

    Full Text Available A modified RP-HPLC method was developed for the quantitative determination of recombinant human insulin in bulk and pharmaceutical dosage form with reduced retention time. Study of the effects of the column temperature, pH of the mobile phase and presence of vial additives (phenol and m-cresol, or impurities (A-21 Disamido on the accuracy of the assay were assessed. Separation was achieved using a Hypersil BDS C-18 column and the mobile phase was composed of solution A (aqueous solution of 28.3 anhydrous Na2SO4g/L, pH 2.3 and solution B (28.5 g anhydrous Na2SO4 g/L in 50:50 mixture of water and acetonitrile, pH 2.3 in a ratio 48:52 (v/v at 45–50 °C. The column temperature was 40 °C, the flow rate was 1 mL/min and detection was performed at 216 nm. The procedures were validated according to international conference on harmonization (ICH guidelines. Recovery study was done applying standard addition technique for further validation of the procedure. The retention time of recombinant human insulin was 19.7 min as compared to 29 min obtained by the reference method. Analytical conditions fluctuations or presence of vial additives or impurities did not show any significant effect on the accuracy of the method. The prepared standard insulin solution in 0.01 N HCl was found to be stable for 5 days. Statistical comparison showed no significant difference between the described method and reference method regarding the accuracy and precision. The modified method can be applied for routine quality control applications for determination of recombinant human insulin.

  6. Optimization of cloud point extraction and solid phase extraction methods for speciation of arsenic in natural water using multivariate technique

    Energy Technology Data Exchange (ETDEWEB)

    Baig, Jameel A., E-mail: jab_mughal@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Kazi, Tasneem G., E-mail: tgkazi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Shah, Abdul Q., E-mail: aqshah07@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Arain, Mohammad B. [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Afridi, Hassan I., E-mail: hassanimranafridi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Kandhro, Ghulam A., E-mail: gakandhro@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan); Khan, Sumaira, E-mail: skhanzai@gmail.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Sindh (Pakistan)

    2009-09-28

    The simple and rapid pre-concentration techniques viz. cloud point extraction (CPE) and solid phase extraction (SPE) were applied for the determination of As{sup 3+} and total inorganic arsenic (iAs) in surface and ground water samples. The As{sup 3+} was formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, after centrifugation the surfactant-rich phase was diluted with 0.1 mol L{sup -1} HNO{sub 3} in methanol. While total iAs in water samples was adsorbed on titanium dioxide (TiO{sub 2}); after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The multivariate strategy was applied to estimate the optimum values of experimental factors for the recovery of As{sup 3+} and total iAs by CPE and SPE. The standard addition method was used to validate the optimized methods. The obtained result showed sufficient recoveries for As{sup 3+} and iAs (>98.0%). The concentration factor in both cases was found to be 40.

  7. Actinide speciation in glass leach-layers: An EXAFS study

    Energy Technology Data Exchange (ETDEWEB)

    Biwer, B.M.; Soderholm, L. [Argonne National Lab., IL (United States); Greegor, R.B. [Boeing Co., Seattle, WA (United States); Lytle, F.W. [EXAFS Co., Pioche, NV (United States)

    1996-12-31

    Uranium L{sub 3} X-ray absorption data were obtained from two borosilicate glasses, which are considered as models for radioactive wasteforms, both before and after leaching. Surface sensitivity to uranium speciation was attained by a novel application of simultaneous fluorescence and electron-yield detection. Changes in speciation are clearly discernible, from U(VI) in the bulk to (UO{sub 2}){sup 2+}-uranyl in the leach layer. The leach-layer uranium concentration variations with leaching times are also determined from the data.

  8. ARSENIC SPECIATION ANALYSIS IN HUMAN SALIVA

    Science.gov (United States)

    Background: Determination of arsenic species in human saliva is potentially useful for biomonitoring of human exposure to arsenic and for studying arsenic metabolism. However, there is no report on the speciation analysis of arsenic in saliva. Methods: Arsenic species in saliva ...

  9. SIMULTANEOUS ESTIMATION AND VALIDATION OF PARACETAMOL, CHLORPHENIRAMINE MALEATE AND PHENYLEPHRINE HYDROCHLORIDE IN BULK AND TABLET DOSAGE FORM BY USING DIFFERENT SPECTROPHOTOMETRIC METHOD

    Directory of Open Access Journals (Sweden)

    Hapse Sandip Appasaheb

    2013-10-01

    Full Text Available A simple, precise, accurate and economic simultaneous UV spectrophotometric method has been developed for the estimation of Paracetamol, Chlorpheniramine Maleate and Phenylephrine Hydrochloride in combination in bulk mixture and tablet. The estimation was based upon measurement of absorbance at absorbance maxima of 258 nm, 262 nm and 239 nm for Paracetamol, Chlorpheniramine Maleate and Phenylephrine Hydrochloride in methanol, respectively in bulk mixture and tablet. The Beer Lambert's law obeyed in the concentration range 4-24 μg/ml, for Paracetamol, Chlorpheniramine Maleate and Phenylephrine Hydrochloride respectively. The estimation of bulk mixture and tablet was carried out by simultaneous equation, Q-analysis and area under curve method for estimation of Paracetamol, Chlorpheniramine Maleate and Phenylephrine Hydrochloride. Recovery study was performed to confirm the accuracy of the methods. The methods were validated as per ICH guidelines.

  10. Improvement of the intersection method for the quantification of filamentous organisms: basis and practice for bulking and foaming bioindication purposes.

    Science.gov (United States)

    Salvadó, Humbert

    2016-09-01

    Bulking and foaming phenomena in activated sludge wastewater treatment plants are in most cases related to the abundance of filamentous microorganisms. Quantifying these microorganisms should be a preliminary stage in their control. In this paper, the simplicity of quantifying them based on the intersection method is demonstrated, by redescribing the theory and applying a new improved protocol; new data of interest are also provided. The improved method allows us to use it with stained smears, including epifluorescence techniques. The error that could be made, when considering the distribution of filamentous bacteria in fresh microscope preparations in two dimensions rather than three is negligible. The effect of the different types of filamentous microorganisms on the settleability was also studied. The effect of the total extended filament length on the sludge settleability was shown to depend on the type of filamentous organism and how it aggregates. When these groups of filamentous organisms are found in small aggregations and there is an increase in the number of filamentous organisms, the sludge volume index (SVI) increases proportionally to the filament length. However, when aggregation increases, the impact on the SVI is significantly lower.

  11. Stability Indicating HPLC Method for Estimation of S-amlodipine besylate and Nebivolol hydrochloride in Bulk Drugs and Marketed Formulation

    Directory of Open Access Journals (Sweden)

    G.V.S Kumar

    2012-10-01

    Full Text Available A simple, precise and stability indicating reversed phase liquid chromatographic method was developed and validated for estimation of s-amlodipine besylate and nebivolol hydrochloride in bulk drug and marketed formulation. The separation was achieved on Zorbax C8 G (250mm x 4.6mm, 5µm analytical column with mobile phase comprising of 0.05M Potassium di hydrogen phosphate: Acetonitrile (pH 3.0 (60:40v/v at isocratic flow of 1.0ml/min with UV detection at 269 nm. The retention times of s-amlodipine besylate and nebivolol hydrochloride was found to be 5.2 and 6.8 minutes respectively. The method was successfully validated in accordance to ICH guidelines for accuracy, precision, specificity, linearity, ruggedness and robustness. The linear regression analysis data for calibration plots showed good linear relationship in the concentration range 0.125-0.375μg/mL for s-amlodipine besylate and 0.25-0.75 for nebivolol hydrochloride. The drugs were exposed to acidic, basic, oxidation, thermal and photolytic stress degradation conditions. The resultant stressed samples were analyzed by the proposed method and was established to provide high resolution among the degradation products and the analytes. All the peaks of degraded product were resolved from the active pharmaceutical ingredient with significantly different retention time and the peak purity of analyte peaks in the stressed samples was confirmed by photodiode array detector. The method could effectively separate the drug from its degradation product; it can be employed as a stability- indicating one.

  12. Development and validation of HPTLC method for simultaneous determination of amlodipine besylate and metoprolol succinate in bulk and tablets

    Directory of Open Access Journals (Sweden)

    P S Jain

    2012-01-01

    Full Text Available A simple, selective, precise high-performance thin-layer chromatographic method for simultaneous determination of amlodipine besylate and metoprolol succinate in bulk and pharmaceutical combined dosage form was developed and validated. The method employed HPTLC aluminum plates precoated with silica gel 60F-254 (10×10 as the stationary phase. The solvent system consisted of toluene:ethyl acetate:methanol:triethylamine (4:1:1:0.4 v/v/v. The system was found to give a compact spot for amlodipine besylate (R f = 0.39±0.02 and metoprolol succinate (R f = 0.59±0.02. Densitometric analysis of amlodipine besylate and metoprolol succinate was carried out in the absorbance mode at 254 nm. Linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.9990±0.0013 with respect to peak area in the concentration range 400-1400 ng per spot for amlodipine besylate and r2 = 0.9993±0.0013 with respect to peak area in the concentration range 3800-13300 ng per spot for metoprolol succinate. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 39.99 and 121.20 ng per spot for amlodipine besylate and 234.31 and 710.03 ng per spot for metoprolol succinate, respectively. Statistical analysis proved that the method is selective, precise and accurate for the estimation of amlodipine and metoprolol.

  13. ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR THE ESTIMATION OF FAROPENEM IN BULK AND PHARMACEUTICAL FORMULATION USING THE RP-HPLC METHOD

    Directory of Open Access Journals (Sweden)

    Iffath Rizwana

    2012-12-01

    Full Text Available A simple, specific and accurate reverse phase high performance liquid chromatographic method was developed for the determination Faropenem in Bulk and pharmaceutical dosage form. The column used was Symmetry C18 (4.6 x 150mm, 5 m, Make: ODS or equivalent in isocratic mode, with mobile phase containing phosphate buffer adjusted the pH-4.0 with orthophosphoric acid and Acetonitrile in the ratio (70:30%v/v the flow rate was 0.9 mL/ min and eluents was monitored at 317 nm. The retention time Faropenem was 3.051 min, respectively. The linearity for Faropenem was in the range of 40-120 µg/ml respectively. The recovery of Faropenem was found to be 100.1%, respectively. The proposed method was validated and successfully applied to the estimation of Faropenem in tablet dosage form.

  14. Fabrication of monolithic bulk Ti3AlC2 and impurity measurement by K-value method

    Institute of Scientific and Technical Information of China (English)

    XU Xue-wen; FU Cheng-ke; LI Yang-xian; ZHU Jiao-qun; MEI Bing-chu

    2006-01-01

    Polycrystalline bulk Ti3AlC2 material with high purity and density was fabricated by hot pressing from the powder mixture with the starting stoichiometric mole ratios of 2.0TiC/ 1.0Ti/ 1.1Al/ 0.1Si at 1 300-1 500 ℃. X-ray diffraction patterns and scanning electron microscopy photographs of the fully dense samples indicate that the proper addition of silicon is favorable to the formation of Ti3AlC2,consequently results in high purity of the prepared samples. The Ti3AlC2 hot pressed at 1 300 ℃ and 1 400 ℃ is in plane-shape with sizes of 6-8 ìm and 15-20 ìm in the elongated dimension,respectively. The purities of samples are measured by the K-value method,and the contents of TiC are given by a linear equation.

  15. Modelling bacterial speciation

    OpenAIRE

    2006-01-01

    A central problem in understanding bacterial speciation is how clusters of closely related strains emerge and persist in the face of recombination. We use a neutral Fisher–Wright model in which genotypes, defined by the alleles at 140 house-keeping loci, change in each generation by mutation or recombination, and examine conditions in which an initially uniform population gives rise to resolved clusters. Where recombination occurs at equal frequency between all members of the population, we o...

  16. Aggression patterns and speciation.

    Science.gov (United States)

    Nevo, E; Naftali, G; Guttman, R

    1975-01-01

    The evolutionary significance of interspecific aggression as a factor in speciation was tested among three chromosome forms of the actively speciating fossorial rodent Spalax ehrenbergi in Israel. Laboratory experiments testing intra- and interspecific aggression were conducted on 48 adult animals from 10 populations comprising three chromosome forms with 2n = 52, 58, and 60. Twelve agonistic, motivational-conflict, and territorial behavioral variables were recorded during 72 combats involving homo- and heter-ogametic encounters between opponents. Analysis of the data matrix was carried out by the nonmetric multivariate Smallest Space Analysis (SSA-II). The results indicate that (a) aggression patterns, involving agonistic conflict and territorial variables, are higher in heterogametic encounters than in homogametic ones; and (b) aggression is higher between contiguous chromosome forms (2n = 58-60, and 2n = 52-58) than between noncontiguous ones (2n = 52-60). Both a and b suggest that high interspecific aggression appears to be adaptively selected at final stages of speciation in mole rats as a premating isolating mechanism which reinforces species identification and establishes parapatric distributions between the evolving species. PMID:1059109

  17. Superconducting and mechanical properties of the bulk Bi(pb)SCCO system prepared via solid state and ammonium nitrate precipitation methods

    Science.gov (United States)

    Safran, S.; Kılıçarslan, E.; Ozturk, H.; Alp, M.; Akdogan, M.; Asikuzun, E.; Ozturk, O.; Kılıç, A.

    2015-09-01

    We have investigated the effect of preparation method on superconducting and mechanical properties of Bi(Pb)-2223 bulk samples using Bi1.85Pb0.35Sr2Ca2Cu3O10±y stoichiometry. Solid-state reaction and ammonium nitrate precipitation methods have been used for fabrication of the bulk samples. In addition, the effect of annealing time on BSCCO samples have been studied. Structural, electrical, magnetic and microhardness analyses of samples are performed by the X-ray powder diffraction (XRD), the Scanning Electron Microscopy (SEM), DC resistivity, AC susceptibility and Vickers microhardness test. The critical transition temperature, phase purity, surface morphology and crystallinity of the prepared bulk samples are compared with each other. Elasticity (E), brittleness (Bi), fracture toughness (KIC) and yield strength (Y) values are also determined according to annealing time, applied load and production parameters of materials.

  18. The EU network on trace element speciation in full swing

    DEFF Research Database (Denmark)

    Cornelis, R.; Camara, C.; Ebdon, L.;

    2000-01-01

    The EC-funded thematic network 'Speciation 21' links scientists in analytical chemistry working in method development for the chemical speciation of trace elements, and potential users from industry and representatives of legislative agencies, in the field of environment, food and occupational...... as the influence of packing materials. Once the analytical methodology for the measurement of the trace element species has been optimised, the importance of trace element speciation will grow enormously. Food sciences, material sciences, medicine and occupational health, environmental sciences and related fields...

  19. Comparative tests of the role of dewlap size in Anolis lizard speciation.

    Science.gov (United States)

    Ingram, Travis; Harrison, Alexis; Mahler, D Luke; Castañeda, María Del Rosario; Glor, Richard E; Herrel, Anthony; Stuart, Yoel E; Losos, Jonathan B

    2016-12-28

    Phenotypic traits may be linked to speciation in two distinct ways: character values may influence the rate of speciation or diversification in the trait may be associated with speciation events. Traits involved in signal transmission, such as the dewlap of Anolis lizards, are often involved in the speciation process. The dewlap is an important visual signal with roles in species recognition and sexual selection, and dewlaps vary among species in relative size as well as colour and pattern. We compile a dataset of relative dewlap size digitized from photographs of 184 anole species from across the genus' geographical range. We use phylogenetic comparative methods to test two hypotheses: that larger dewlaps are associated with higher speciation rates, and that relative dewlap area diversifies according to a speciational model of evolution. We find no evidence of trait-dependent speciation, indicating that larger signals do not enhance any role the dewlap has in promoting speciation. Instead, we find a signal of mixed speciational and gradual trait evolution, with a particularly strong signal of speciational change in the dewlaps of mainland lineages. This indicates that dewlap size diversifies in association with the speciation process, suggesting that divergent selection may play a role in the macroevolution of this signalling trait.

  20. A validated stability indicating HPLC method for the determination of process-related impurities in pantoprazole bulk drug and formulations

    Directory of Open Access Journals (Sweden)

    Saurabh Pandey

    2013-03-01

    Full Text Available A stability-indicating high-performance liquid chromatographic (HPLC method was developed with short run time and validated for the assay of process related impurities of pantoprazole in bulk form. Resolution of drug, its potential impurities and degradation products were achieved on a Hypersil ODS column utilizing a gradient with 0.01 M phosphate buffer of pH 7 and acetonitrile as eluent, at the detection wavelength of 290 nm. Flow rate was set at 1 mL min-1. The procedure was found to be specific, linear (r=0.999, recovery (97.9-103%, LOD (0.043-0.047 µgmL-1, LOQ (0.13-0.14 µgmL-1 and robust. Acceptable robustness indicates that the assay method remains unaffected by small but deliberate variations. Pantoprazole was found to degrade in acidic, oxidative and under photolytic stress conditions. The drug was stable to alkaline and dry heat conditions. This method has been successively applied to pharmaceutical formulation and no interference from the excipients was found.Desenvolveu-se método indicador de estabilidade por Cromatografia a Líquido de Alta Eficiência (CLAE com pequeno tempo de corrida e validado para o ensaio de impurezas relacionadas ao processo de produção de pantoprazol em batelada. A determinação do fármaco, de suas impurezas potenciais e dos produtos de degradação foi realizada com coluna de ODS Hypersil, utilizando gradiente com tampão de fosfato 0,01 M pH 7 e acetonitrila como eluente, no comprimento de onda de detecção de 290 nm. A velocidade de fluxo foi fixada em 1 mLmin-1. O procedimento se mostrou específico, linear (r=0,999, com recuperação (97,9-103%, LOD (0,043-0,047 µgmL-1, LOQ (0,13-0,14 µg mL-1 e robusto. Robustez aceitável indica que o método de ensaio não é afetado por variações pequenas, exceto as planejadas. O pantoprazole degradou em condições ácidas, oxidativas e sob condições de estresse fotolítico. O fármaco foi estável em condições alcalinas e de calor seco. Este m

  1. Redox speciation of final repository relevant elements using separation methods in combination with ICP mass spectrometry; Redoxspeziation von endlagerrelevanten Elementen mit Hilfe von Trennmethoden gekoppelt an ein Massenspektrometer mit induktiv gekoppeltem Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Graser, Carl-Heinrich

    2015-12-18

    The long-term safety assessment for nuclear waste repositories requires a detailed understanding of the chemistry of actinide elements in the geosphere. The development of advanced analytical tools is required to gain detailed insights into actinide redox speciation in a given system. The mobility of radionuclides is mostly determined by the geochemical conditions which control the redox state of radionuclides. Besides the longlived radionuclides plutonium (Pu) and neptunium (Np), which are key elements in high level nuclear waste, iron (Fe) represents a main component in natural systems controlling redox related geochemical processes. Analytical techniques for determining oxidation state distribution for redox sensitive radionuclides and other metal ions often have a lack of sensitivity. The detection limits of these methods (i.e. UV/vis, TRLFS, XANES) are in general in the range of ≥ 10{sup -6} mol.L{sup -1}. As a consequence ultrasensitive new analytical techniques are required. Capillary electrophoresis (CE) and ion chromatography (IC) are powerful separation methods for metal ions. In the course of this thesis different speciation method for iron, neptunium and plutonium were optimized. With the optimized setup redox speciation analysis of these elements in different samples were done. Furthermore CE hyphenated to inductively coupled plasma sector field mass spectrometry (CE - ICP - SF - MS) was used to measure the redox speciation of Pu (III, IV, V, VI), Np (IV, V, VI) and Fe (II, III) at concentrations lower than 10{sup -7} mol.L{sup -1}. CE coupling and separation parameters such as sample gas pressure, make up flow rate, capillary position, auxiliary gas flow, as well as the electrolyte system were optimized to obtain the maximum sensitivity. The methodes detection limits are 10{sup -12} mol.L{sup -1} for Np and Pu. The various oxidation state species of Pu and Np in different samples were separated by application of an acetate based electrolyte system

  2. Especiação analítica de compostos de arsênio empregando métodos voltamétricos e polarográficos: uma revisão comparativa de suas principais vantagens e aplicações Speciation analysis of arsenic compounds by voltammetric and polarographic methods: a comparative review of their main advantages and applications

    Directory of Open Access Journals (Sweden)

    Leandro Machado de Carvalho

    2004-04-01

    Full Text Available This paper provides a review on voltammetric and polarographic methods for the speciation analysis of inorganic and organic arsenic compounds in different matrices. A discussion on the main advantages of electroanalytical methods in comparison with other analytical methods employed for arsenic speciation is presented. The mechanistic aspects of the most relevant techniques employing cathodic and anodic stripping voltammetry as well as polarographic methods published in the last twenty five years are summarized and discussed. The bibliographic references cited in this work were selected from the Web of Science (published by the ISI and the main journals of analytical chemistry.

  3. Speciation of long-lived radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolin Hou

    2008-11-15

    This project started in November 2005 and ended in November 2008, the work and research approaches are summarized in this report. This project studied the speciation of radionuclides in environment. A number of speciation analytical methods are developed for determination of species of 129I, 99Tc, isotopes of Pu, and 237Np in seawater, fresh water, soil, sediment, vegetations, and concrete. The developed methods are used for the investigation of the chemical speciation of these radionuclides as well as their environmental behaviours, especially in Danish environment. In addition the speciation of Pu isotopes in waste samples from the decommissioning of Danish nuclear facilities is also investigated. The report summarizes these works completed in this project. Through this research project, a number of research papers have been published in the scientific journals, the research results has also been presented in the Nordic and international conference/meeting and communicated to international colleagues. Some publications are also enclosed to this report. (au)

  4. Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

    Science.gov (United States)

    Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

    2013-03-01

    The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

  5. The drivers of tropical speciation.

    Science.gov (United States)

    Smith, Brian Tilston; McCormack, John E; Cuervo, Andrés M; Hickerson, Michael J; Aleixo, Alexandre; Cadena, Carlos Daniel; Pérez-Emán, Jorge; Burney, Curtis W; Xie, Xiaoou; Harvey, Michael G; Faircloth, Brant C; Glenn, Travis C; Derryberry, Elizabeth P; Prejean, Jesse; Fields, Samantha; Brumfield, Robb T

    2014-11-20

    Since the recognition that allopatric speciation can be induced by large-scale reconfigurations of the landscape that isolate formerly continuous populations, such as the separation of continents by plate tectonics, the uplift of mountains or the formation of large rivers, landscape change has been viewed as a primary driver of biological diversification. This process is referred to in biogeography as vicariance. In the most species-rich region of the world, the Neotropics, the sundering of populations associated with the Andean uplift is ascribed this principal role in speciation. An alternative model posits that rather than being directly linked to landscape change, allopatric speciation is initiated to a greater extent by dispersal events, with the principal drivers of speciation being organism-specific abilities to persist and disperse in the landscape. Landscape change is not a necessity for speciation in this model. Here we show that spatial and temporal patterns of genetic differentiation in Neotropical birds are highly discordant across lineages and are not reconcilable with a model linking speciation solely to landscape change. Instead, the strongest predictors of speciation are the amount of time a lineage has persisted in the landscape and the ability of birds to move through the landscape matrix. These results, augmented by the observation that most species-level diversity originated after episodes of major Andean uplift in the Neogene period, suggest that dispersal and differentiation on a matrix previously shaped by large-scale landscape events was a major driver of avian speciation in lowland Neotropical rainforests.

  6. Development and validation of a simple UV spectrophotometric method for the determination of levofloxacin both in bulk and marketed dosage formulations

    Institute of Scientific and Technical Information of China (English)

    Mahfuza Maleque; Md. Raquibul Hasan; Farhad Hossen; Sanjana Sail

    2012-01-01

    A rapid, specific and economic UV spectrophotometric method has been developed using a solvent composed of water:methanol:acetonitrile (9:0.5:0.5) to determine the levofloxacin content in bulk and pharmaceutical dosage formulations. At a pre-determined 2 of 292 nm, it was proved linear in the range of 1.0 12.0 μg/mL, and exhibited good correlation coefficient (R2=0.9998) and excellent mean recovery (99.0-100.07%). This method was successfully applied to the determination of levofloxacin content in five marketed brands from Bangladesh and the results were in good agreement with the label claims. The method was validated statistically and by recovery studies for linearity, precision, repeatability, and reproducibility. The obtained results proved that the method can be employed for the routine analysis of levofloxacin in bulks as well as in the commercial formulations.

  7. Bulk meltwater flow and liquid water content of snowpacks mapped using the electrical self-potential (SP) method

    Science.gov (United States)

    Thompson, Sarah S.; Kulessa, Bernd; Essery, Richard L. H.; Lüthi, Martin P.

    2016-02-01

    Our ability to measure, quantify and assimilate hydrological properties and processes of snow in operational models is disproportionally poor compared to the significance of seasonal snowmelt as a global water resource and major risk factor in flood and avalanche forecasting. We show here that strong electrical self-potential fields are generated in melting in situ snowpacks at Rhone Glacier and Jungfraujoch Glacier, Switzerland. In agreement with theory, the diurnal evolution of self-potential magnitudes ( ˜ 60-250 mV) relates to those of bulk meltwater fluxes (0-1.2 × 10-6 m3 s-1) principally through the permeability and the content, electrical conductivity and pH of liquid water. Previous work revealed that when fresh snow melts, ions are eluted in sequence and electrical conductivity, pH and self-potential data change diagnostically. Our snowpacks had experienced earlier stages of melt, and complementary snow pit measurements revealed that electrical conductivity ( ˜ 1-5 × 10-6 S m-1) and pH ( ˜ 6.5-6.7) as well as permeabilities (respectively ˜ 9.7 × 10-5 and ˜ 4.3 × 10-5 m2 at Rhone Glacier and Jungfraujoch Glacier) were invariant. This implies, first, that preferential elution of ions was complete and, second, that our self-potential measurements reflect daily changes in liquid water contents. These were calculated to increase within the pendular regime from ˜ 1 to 5 and ˜ 3 to 5.5 % respectively at Rhone Glacier and Jungfraujoch Glacier, as confirmed by ground truth measurements. We conclude that the electrical self-potential method is a promising snow and firn hydrology sensor owing to its suitability for (1) sensing lateral and vertical liquid water flows directly and minimally invasively, (2) complementing established observational programs through multidimensional spatial mapping of meltwater fluxes or liquid water content and (3) monitoring autonomously at a low cost. Future work should focus on the development of self-potential sensor

  8. A Method for Determining Bulk Density, Material Density, and Porosity of Melter Feed During Nuclear Waste Vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Hilliard, Zachary J.; Hrma, Pavel R.

    2016-01-31

    Abstract Glass making efficiency largely depends on heat transfer to reacting glass batch (melter feed), which in turn is influenced by the bulk density (ρb) and porosity (Φ) as functions of temperature (T). Neither b(T) nor Φ(T) functions are readily accessible to direct measurement, but they can be determined based on monitoring the profile area of heated glass batch pellets and material density of batches quenched at various stages of conversion via pycnometry. For the determination of Φb, the bulk volume must be calculated as a function of temperature. This is done via a program constructed in MATLAB which takes an image of a pellet profile at a given temperature and calculates the volume of said pellet. The quenched density measured by pycnometry must be converted to the density at heat treatment temperature. This is done by taking into account the volume change due to thermal expansion/contraction.

  9. Investigating ecological speciation in non-model organisms

    DEFF Research Database (Denmark)

    Foote, Andrew David

    2012-01-01

    Background: Studies of ecological speciation tend to focus on a few model biological systems. In contrast, few studies on non-model organisms have been able to infer ecological speciation as the underlying mechanism of evolutionary divergence. Questions: What are the pitfalls in studying ecological...... speciation in non-model organisms that lead to this bias? What alternative approaches might redress the balance? Organism: Genetically differentiated types of the killer whale (Orcinus orca) exhibiting differences in prey preference, habitat use, morphology, and behaviour. Methods: Review of the literature...... variation underlie reproductive isolation between sympatric killer whale types. Perhaps ecological speciation has occurred, but it is hard to prove. We will probably face this outcome whenever we wish to address non-model organisms – species in which it is not easy to apply experimental approaches...

  10. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel;

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  11. Bulk MgB2 superconductor with high critical current density synthesized by self-propagating high-temperature synthesis method

    Institute of Scientific and Technical Information of China (English)

    Feng Wang-Jun; Xia Tian-Dong; Liu Tian-Zuo; Zhao Wen-Jun; Wei Zhi-Qiang

    2005-01-01

    Pure MgB2 bulk samples are successfully synthesized by self-propagating high-temperature synthesis (SHS)method. The experiments show that the best preheating temperature is 250℃, the highest Jc values of the prepared MgB2 reach 1.5×106A/cm2 (10K, 0.5T) and 1.7×106A/cm2 (20K, 0T), and the MgB2 particle sizes range from 2 to 5μm. The advantages of this method are that it is simple, economical and suitable for the manufacture of bulk MgB2 materials on industrial scale.

  12. Method optimization and quality assurance in speciation analysis using high performance liquid chromatography with detection by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt

    1998-01-01

    operating characteristics of the entire hyphenated system. An isocratic HPLC system, which employs an aqueous mobile phase with organic buffer constituents, is well suited for introduction into the ICP-MS because of the stability of the detector response and high degree of analyte sensitivity attained......Achievement of optimum selectivity, sensitivity and robustness in speciation analysis using high performance liquid chromatography (HPLC) with inductively coupled mass spectrometry (ICP-MS) detection requires that each instrumental component is selected and optimized with a view to the ideal....... Anion and cation exchange HPLC systems, which meet these requirements, were used for the separation of selenium and arsenic species in crude extracts of biological samples. Furthermore, the signal-to-noise ratios obtained for these incompletely ionized elements in the argon ICP were further enhanced...

  13. Superconducting and mechanical properties of the bulk Bi(pb)SCCO system prepared via solid state and ammonium nitrate precipitation methods

    Energy Technology Data Exchange (ETDEWEB)

    Safran, S., E-mail: safran@science.ankara.edu.tr [Ankara University, Faculty of Science, Department of Physics, Tandoğan, Ankara 06100 (Turkey); Center of Excellence for Superconductivity Research, 50 Year Campus, Golbaşı, Ankara (Turkey); Kılıçarslan, E.; Ozturk, H. [Ankara University, Faculty of Science, Department of Physics, Tandoğan, Ankara 06100 (Turkey); Center of Excellence for Superconductivity Research, 50 Year Campus, Golbaşı, Ankara (Turkey); Alp, M. [Center of Excellence for Superconductivity Research, 50 Year Campus, Golbaşı, Ankara (Turkey); Akdogan, M. [Center of Excellence for Superconductivity Research, 50 Year Campus, Golbaşı, Ankara (Turkey); Abant İzzet Baysal University, Department of Physics, Bolu (Turkey); Asikuzun, E.; Ozturk, O. [Kastamonu University, Department of Physics, Kastamonu (Turkey); Kastamonu University, Research and Application Center, Kastamonu (Turkey); Kılıç, A. [Ankara University, Faculty of Science, Department of Physics, Tandoğan, Ankara 06100 (Turkey); Center of Excellence for Superconductivity Research, 50 Year Campus, Golbaşı, Ankara (Turkey)

    2015-09-01

    We have investigated the effect of preparation method on superconducting and mechanical properties of Bi(Pb)-2223 bulk samples using Bi{sub 1.85}Pb{sub 0.35}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10±y} stoichiometry. Solid-state reaction and ammonium nitrate precipitation methods have been used for fabrication of the bulk samples. In addition, the effect of annealing time on BSCCO samples have been studied. Structural, electrical, magnetic and microhardness analyses of samples are performed by the X-ray powder diffraction (XRD), the Scanning Electron Microscopy (SEM), DC resistivity, AC susceptibility and Vickers microhardness test. The critical transition temperature, phase purity, surface morphology and crystallinity of the prepared bulk samples are compared with each other. Elasticity (E), brittleness (B{sub i}), fracture toughness (K{sub IC}) and yield strength (Y) values are also determined according to annealing time, applied load and production parameters of materials.

  14. Effect of cooking method on the fatty acid content of reduced-fat and PUFA-enriched pork patties formulated with a konjac-based oil bulking system.

    Science.gov (United States)

    Salcedo-Sandoval, Lorena; Cofrades, Susana; Ruiz-Capillas, Claudia; Jiménez-Colmenero, Francisco

    2014-12-01

    The effect of cooking methods (electric grilling and pan-frying in olive oil) on the composition of reduced-fat and reduced-fat/PUFA enriched pork patties was studied. Fat reduction was performed by replacing pork backfat (38% and 100%) with konjac gel and PUFA-enrichment by replacing pork backfat (49%) with a konjac-based oil bulking system stabilizing a healthier oil combination (olive, linseed and fish oils). Cooking losses (13%-27%) were affected (pfat/improved sample containing the oil bulking system ranged between 1.4 and 1.6g/100g (0.47-0.51 from n-3 PUFAs), with EPA+DHA concentrations of around 75mg/100g. Konjac materials were successfully used to produce pork patties with a better lipid composition.

  15. Growth by the Multi-tube Physical Vapour Transport method and characterisation of bulk (Cd,Zn)Te

    Science.gov (United States)

    Choubey, A.; Veeramani, P.; Pym, A. T. G.; Mullins, J. T.; Sellin, P. J.; Brinkman, A. W.; Radley, I.; Basu, A.; Tanner, B. K.

    2012-08-01

    Growth by the Multi-tube Physical Vapour Transport technique and characterisation of bulk (Cd,Zn)Te is described. The crystalline perfection and uniformity of zinc content have been mapped by infra-red transmission and microscopy, X-ray diffraction and photoluminescence. X-ray double crystal rocking curve full widths at half maximum as low as 43 in have been obtained and a mean zinc mole fraction of 0.03 has been found to vary by less than ±0.003 over the diameter of a 50 mm boule. The material exhibits a resistivity in the 2×109Ω cm range and planar devices fabricated from this material have shown electron mobility lifetime products of 4.07×10-3 cm2 V-1.

  16. Development and Validation of Stability Indicating Uv and Rp-Hplc Method for the Estimation of Flupritine Maleate in Bulk and Formulations

    Directory of Open Access Journals (Sweden)

    D. Gowrisankar

    2014-12-01

    Full Text Available The objective of the study was to develop stability indicatingUV spectroscopy and RP-HPLC method for the estimation of flupritine maleate in bulk and marketed tablets. Chromatographic separation was achieved on Agilent Eclipse C18, 150 x 4.6 mm, 5m with mobile phase consisting of Buffer(1 ml OPA and 1 ml TEA in 1000 ml water and pH was adjusted to 3 with dilute OPA and Methanol are taken in 50:50%v/v. The effluent was monitored at 246 nm. A sharp peak was observed at 4.0 min. UV Spectrophotometric method was performed at 250 nm using methanol as the solvent. R2=0.999 for HPLC method and R2=0.998 for UV Spectrophotometric method. The method was validated as per ICH guidelines with linearity, precision, accuracy, robustness, ruggedness and specificity.Statistical analysis showed that both the methods were precise, accurate, sensitive, and Stability indicating can be used for the routine analysis of flupritine economically in bulk and commercial formulations.

  17. Development and Validation of UV-Visible Spectrophotometric Methods for Simultaneous Estimation of Thiocolchicoside and Dexketoprofen in Bulk and Tablet Dosage Form

    Directory of Open Access Journals (Sweden)

    M. T. Harde

    2012-04-01

    Full Text Available Development and validation of two simple, accurate, precise and economical UV Spectrophotometric methods for simultaneous estimation of Thiocolchicoside and Dexketoprofen in bulk and in tablet dosage form. The methods employed were Method-1 Absorbance correction method and Method-2 First order derivative spectroscopic method. In method-1 Absorbance is measured at two wavelengths 370nm at which Dexketoprofen has no absorbance and 255nm at which both the drug have considerable absorbance. In method-2, two wavelengths 232nm for Thiocolchicoside (zero cross for Dexketoprofen and 242nm for Dexketoprofen (zero cross for Thiocolchicoside were selected. The beers law obeyed in the concentration range 4-40µg/ml and 5-50µg/ml for Thiocolchicoside and Dexketoprofen respectively in methanol. The suggested method is validated by using ICH validation parameters like accuracy, precision, linearity, LOD and LOQ respectively. Recovery study values of Thiocolchicoside and Dexketoprofen was found 99.8% and 100.2% respectively for both the methods. Standard deviation and RSD for intra-day and inter-day precision studies was found to be less than ± 2. The linearity coefficient was found 0.9996 at 242nm and 0.999 at 255 nm for Dexketoprofen and 0.9997 at both 232nm and 370nm for Thiocolchicoside. The LOD and LOQ for Method-1 were found to be 0.0067μg/ml and 0.020μg/ml for Thiocolchicoside, 0.043μg/ml and 0.132μg/ml for Dexketoprofen and for Method-2 were found to be 0.0093μg/ml and 0.028μg/ml for Thiocolchicoside, 0.055μg/ml and 0.168μg/ml for Dexketoprofen respectively. The developed methods were successfully applied to estimate the amount of Thiocolchicoside and Dexketoprofen in bulk and tablet dosage form.

  18. 基于磁滞效应的YBCO块材磁刚度测试方法%YBCO bulk magnetic stiffness measuring method based on magnetic hysteretic effect

    Institute of Scientific and Technical Information of China (English)

    芦逸云; 段晓明; 王家素

    2011-01-01

    处于外磁场中的高温超导块材具有自稳定性.这种特性使得高温超导块材在磁悬浮轴承、飞轮储能、磁悬浮列车等方面,具有潜在的应用价值.非理想高温超导体具有很强的磁通钉扎特性,表现出很强的磁滞性.处于悬浮状态的高稳超导体,其稳定特性与其悬浮刚度密不可分.文中首先描述了高温超导块材磁悬浮测试系统磁刚度测试原理.此刚度测试方法充分考虑了非理想高温超导块材磁滞效应对磁刚度的影响.基于这种测试方法,研究了YBCO块材在永磁轨道上方悬浮力刚度的特性.通过与传统刚度测试方法比较,这种方法更能反应高温超导磁悬浮车实际磁刚度特性.%High - temperature superconducting bulk can stably levitate above permanent magnet. These characteristics make it possible for HTS bulk to be used in magnetic levitation bear, magnetic levitation flying wheel energy storing system and magnetic levitation transportation system. HTS has the characteristics of strong flux ping and then exhibits high magnetic hysteretic. For stable levitation of HTS bulk, there is a tight relationship between its stable property and magnetic levitation stiffness. This paper described the principle of magnetic stiffness measurement of HTS magnetic levitation system. This method considerd the influence of HTS bulk hysteretic of magnetic stiffness measurement. Based on the method, we researched YBCO bulk magnetic levitation stiffness property above permanent magnet gnideway. Compared with two experimental research results, it is found that this method can do well for magnetic levitation system optimum design.

  19. Arabidopsis hybrid speciation processes.

    Science.gov (United States)

    Schmickl, Roswitha; Koch, Marcus A

    2011-08-23

    The genus Arabidopsis provides a unique opportunity to study fundamental biological questions in plant sciences using the diploid model species Arabidopsis thaliana and Arabidopsis lyrata. However, only a few studies have focused on introgression and hybrid speciation in Arabidopsis, although polyploidy is a common phenomenon within this genus. More recently, there is growing evidence of significant gene flow between the various Arabidopsis species. So far, we know Arabidopsis suecica and Arabidopsis kamchatica as fully stabilized allopolyploid species. Both species evolved during Pleistocene glaciation and deglaciation cycles in Fennoscandinavia and the amphi-Beringian region, respectively. These hybrid studies were conducted either on a phylogeographic scale or reconstructed experimentally in the laboratory. In our study we focus at a regional and population level. Our research area is located in the foothills of the eastern Austrian Alps, where two Arabidopsis species, Arabidopsis arenosa and A. lyrata ssp. petraea, are sympatrically distributed. Our hypothesis of genetic introgression, migration, and adaptation to the changing environment during the Pleistocene has been confirmed: We observed significant, mainly unidirectional gene flow between the two species, which has given rise to the tetraploid A. lyrata. This cytotype was able to escape from the narrow ecological niche occupied by diploid A. lyrata ssp. petraea on limestone outcrops by migrating northward into siliceous areas, leaving behind a trail of genetic differentiation.

  20. DEVELOPMENT AND VALIDATION OF STABILITY-INDICATING TLC-DENSITOMETRY METHOD FOR THE SIMULTANEOUS DETERMINATION OF EPERISONE HYDROCHLORIDE AND PARACETAMOL IN BULK AND TABLET DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Pritam S. Jain

    2013-08-01

    Full Text Available A rapid and reproducible stability indicating TLC-densitometric method was developed for the determination of eperisone hydrochloride and paracetamol in presence of their degraded products in bulk drugs and pharmaceutical formulations. Uniform degradation conditions were maintained by refluxing reaction mixtures for 8 h at 60°C including acidic, alkaline hydrolysis. Oxidation at room temperature, photochemical and dry heating degradation studies were also carried out. A sensitive and robust stability indicating TLC-densitometric method for simultaneous quantification of eperisone hydrochloride and paracetamol in bulk drugs and pharmaceutical formulations has been developed and validated. Separation was done on TLC aluminum sheets, pre-coated with silica gel 60F-254 using ethyl acetate: toluene: methanol (2:2:1 v/v/v. Spots at Rf 0.42 ± 0.04 and Rf 0.60 ± 0.02 were recognized as paracetamol and eperisone hydrochloride, respectively. Densitometric analysis of chromatoplates was carried out in absorbance mode at isobastic point 260 nm. The developed method was optimized and validated as per ICH guidelines. Method was found linear over the concentration range of 100-350 ng / spot for eperisone hydrochloride and 600-2100 ng / spot for paracetamol with the correlation coefficient (r2 of 0.999 and 0.999 for eperisone hydrochloride and paracetamol, respectively. The developed TLC method can be applied for routine analysis of eperisone hydrochloride and paracetamol in presence of their degraded products in their combined pharmaceutical formulations.

  1. Selenium Speciation and Management in Wet FGD Systems

    Energy Technology Data Exchange (ETDEWEB)

    Searcy, K; Richardson, M; Blythe, G; Wallschlaeger, D; Chu, P; Dene, C

    2012-02-29

    rapidly than it sorbs to ferric solids. Though it was not possible to demonstrate a decrease in selenium concentrations to levels below the project'ale testing were evident at the pilot scale. Specifically, reducing oxidation air rate and ORP tends to either retain selenium as selenite in the liquor or shift selenium phase partitioning to the solid phase. Oxidation air flow rate control may be one option for managing selenium behavior in FGD scrubbers. Units that cycle load widely may find it more difficult to impact ORP conditions with oxidation air flow rate control alone. Because decreasing oxidation air rates to the reaction tank showed that all new selenium reported to the solids, the addition of ferric chloride to the pilot scrubber could not show further improvements in selenium behavior. Ferric chloride addition did shift mercury to the slurry solids, specifically to the fine particles. Several competing pathways may govern the reporting of selenium to the slurry solids: co-precipitation with gypsum into the bulk solids and sorption or co-precipitation with iron into the fine particles. Simultaneous measurement of selenium and mercury behavior suggests a holistic management strategy is best to optimize the fate of both of these elements in FGD waters. Work conducted under this project evaluated sample handling and analytical methods for selenium speciation in FGD waters. Three analytical techniques and several preservation methods were employed. Measurements of selenium speciation over time indicated that for accurate selenium speciation, it is best to conduct measurements on unpreserved, filtered samples as soon after sampling as possible. The capital and operating costs for two selenium management strategies were considered: ferric chloride addition and oxidation air flow rate control. For ferric chloride addition, as might be expected the reagent makeup costs dominate the overall costs, and range from 0.22 to 0.29 mills/kWh. For oxidation air flow rate

  2. Molybdenum Speciation and its Impact on Catalytic Activity during Methane Dehydroaromatization in Zeolite ZSM-5 as Revealed by Operando X-Ray Methods.

    Science.gov (United States)

    Lezcano-González, Inés; Oord, Ramon; Rovezzi, Mauro; Glatzel, Pieter; Botchway, Stanley W; Weckhuysen, Bert M; Beale, Andrew M

    2016-04-18

    Combined high-resolution fluorescence detection X-ray absorption near-edge spectroscopy, X-ray diffraction, and X-ray emission spectroscopy have been employed under operando conditions to obtain detailed new insight into the nature of the Mo species on zeolite ZSM-5 during methane dehydroaromatization. The results show that isolated Mo-oxo species present after calcination are converted by CH4 into metastable MoCx Oy species, which are primarily responsible for C2 Hx /C3 Hx formation. Further carburization leads to MoC3 clusters, whose presence coincides with benzene formation. Both sintering of MoC3 and accumulation of large hydrocarbons on the external surface, evidenced by fluorescence-lifetime imaging microscopy, are principally responsible for the decrease in catalytic performance. These results show the importance of controlling Mo speciation to achieve the desired product formation, which has important implications for realizing the impact of CH4 as a source for platform chemicals.

  3. Development and validation of a reversed-phase HPLC method for separation and simultaneous determination of process-related substances of mirtazapine in bulk drugs and formulations.

    Science.gov (United States)

    Rao, R Nageswara; Raju, A Narasa

    2009-03-01

    A simple and rapid reversed-phase high-performance liquid chromatographic method has been developed for the separation and simultaneous determination of related substances of mirtazapine in bulk drugs and pharmaceutical formulations. Six impurities, including one degradation product of mirtazapine, have been separated on a BDS Hypersil (4.6 x 250 mm; particle size 5 microm) column with a mobile phase consisting of 0.3% triethylamine (pH 3.0)-acetonitrile (78:22 v/v) eluted in an isocratic mode and monitored with a photo diode array detector at 215 nm. The chromatographic behavior of all the analytes was studied under variable compositions of different solvent systems, temperatures, buffer concentrations, and pH values. The method was validated in terms of accuracy, precision, and linearity. The inter- and intra-day assay precision was found to be method was successfully applied to the analysis of commercial formulations and the recoveries of mirtazapine were in the range of 99.38-100.73% with method is useful not only for rapid evaluation of the purity of mirtazapine, but also for the simultaneous determination of related substances in bulk drugs and pharmaceutical formulations.

  4. Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles

    NARCIS (Netherlands)

    Zielinska, K.

    2014-01-01

    Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid phas

  5. Development and Validation of a RP-Ultra performance liquid chromatographic Method for Quantification of Topotecan Hydrochloride in Bulk and Injection Dosage Form.

    Science.gov (United States)

    Saini, P K; Jain, C L; Singh, R M; Mathur, S C; Singh, G N

    2010-07-01

    A simple, very fast, precise and accurate reverse phase ultra performance liquid chromatographic method was developed for the determination and validation of topotecan hydrochloride in bulk and injection dosage form. A Waters BEH C18, 50×2.1 mm, 1.7 μm particle size column in gradient mode was used with mobile phase comprising of 0.1% v/v orthophosphoric acid in water and acetonitrile. The analytical column was thermostated at 50° and flow rate was set at 0.4 ml per min, with photo diode array detection at 260 nm. The retention time of topotecan was found 1.38 min. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found linear between 20 to 60 μg/ml. The limit of detection and limit of quantification were found 0.2353 and 0.7131 μg/ml, respectively. Percentage recoveries were obtained in the range of 98.91% and 99.17%. The proposed method is precise, accurate, selective and reproducible. The ultra performance liquid chromatographic assay procedure, which proved superior because of its greater sensitivity and relatively shorter (4 min) run time, should be an important tool for speedy future analysis of topotecan hydrochloride in bulk and its injection dosage form.

  6. Radiative Bulk Viscosity

    CERN Document Server

    Chen, X

    2001-01-01

    Viscous resistance to changes in the volume of a gas arises when different degrees of freedom have different relaxation times. Collisions tend to oppose the resulting departures from equilibrium and, in so doing, generate entropy. Even for a classical gas of hard spheres, when the mean free paths or mean flight times of constituent particles are long, we find a nonvanishing bulk viscosity. Here we apply a method recently used to uncover this result for a classical rarefied gas to radiative transfer theory and derive an expression for the radiative stress tensor for a gray medium with absorption and Thomson scattering. We determine the transport coefficients through the calculation of the comoving entropy generation. When scattering dominates absorption, the bulk viscosity becomes much larger than either the shear viscosity or the thermal conductivity.

  7. DEVELOPMENT AND VALIDATION OF A RP- HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF OMEPRAZOLE AND CINITAPRIDE IN BULK AND CAPSULE DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    G. Nagarajan

    2013-02-01

    Full Text Available A simple reversed-phase high-performance liquid chromatographic (RP-HPLC method has been developed and validated for simultaneous determination of Omeprazole and Cinitapride in bulk and Capsule dosage form. Chromatographic analysis was performed on a Symmetry C8 column (150x 4.5 mm, 5μm column ambient temperature with a mixture of mixed phosphate buffer and Acetonitrile in the ratio 50:50 (mixed phosphate buffer preparation; 1.625 gm of potassium Dihydrogen phosphate and 0.3 gm of Di potassium hydrogen phosphate in 550 mL HPLC grade water, pH= 6.0 adjust with phosphoric acid as mobile phase, at a flow rate of 1.0 mL min-1. UV detection was performed at 287 nm. The method was validated for accuracy, precision, specificity, linearity and sensitivity. The retention times of Omeprazole and Cinitapride were 2.49 and 3.650 min, respectively. Calibration plots were linear over the concentration ranges 5–30 μg mL-1 and 0.75-4.5 μg mL-1 for Omeprazole and Cinitapride, respectively. The Limit of detection was 1.43570 and 0.086 µg mL-1 and the quantification limit was 4.35 µg mL-1 and 0.26 µg mL-1 for Omeprazole and Cinitapride, respectively. The accuracy of the proposed method was determined by recovery studies and found to be 98.62% to 100.37%. Commercial capsule formulation was successfully analyzed using the developed method and the proposed method is applicable to routine analysis of determination of Omeprazole and Cinitapride in bulk and capsule dosage form.

  8. How common is homoploid hybrid speciation?

    Science.gov (United States)

    Schumer, Molly; Rosenthal, Gil G; Andolfatto, Peter

    2014-06-01

    Hybridization has long been considered a process that prevents divergence between species. In contrast to this historical view, an increasing number of empirical studies claim to show evidence for hybrid speciation without a ploidy change. However, the importance of hybridization as a route to speciation is poorly understood, and many claims have been made with insufficient evidence that hybridization played a role in the speciation process. We propose criteria to determine the strength of evidence for homoploid hybrid speciation. Based on an evaluation of the literature using this framework, we conclude that although hybridization appears to be common, evidence for an important role of hybridization in homoploid speciation is more circumscribed.

  9. Development and Validation of a Reversed-Phase Chiral HPLC Method to Determine the Chiral Purity of Bulk Batches of (S)-Enantiomer in Afoxolaner.

    Science.gov (United States)

    Kumar, Satish; Rustum, Abu; Padivitage, Nilusha

    2016-10-13

    Afoxolaner is a new antiparasitic molecule from the isoxazoline family that acts on insect acarine γ-aminobutyric acid and glutamate receptors. Afoxolaner is a racemic mixture, which has a chiral center at the isoxazoline ring. A reversed-phase chiral HPLC method has been developed to determine the chiral purity of bulk batches of (S)-enantiomer in afoxolaner for the first time. This method can also be used to verify that afoxolaner is a racemic mixture, which was demonstrated by specific rotation. ChromSword, an artificial intelligence method development tool, was used for initial method development. The column selected for the final method was CHIRALPAK AD-RH (150 × 4.6 mm, 5 μm particle size), maintained at 45°C, and isocratic elution using water-isopropanol-acetonitrile (40 + 50 + 10, v/v/v) as the mobile phase with a detection wavelength of 312 nm. The run time for the method was 11 min. The resolution and selectivity factors of the two enantiomers were 2.3 and 1.24, respectively. LOQ and LOD of the method were 1.6 and 0.8 μg/mL, respectively. This method was appropriately validated according to International Conference on Harmonization guidelines for its intended use.

  10. Plutonium Speciation in Support of Oxidative-Leaching Demonstration Test

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.

    2007-10-31

    Bechtel National, Inc. (BNI) is evaluating the plutonium speciation in caustic solutions that reasonably represent the process streams from the oxidative-leaching demonstration test. Battelle—Pacific Northwest Division (PNWD) was contracted to develop a spectrophotometric method to measure plutonium speciation at submicromolar (< 10-6 M) concentrations in alkaline solutions in the presence of chromate and carbonate. Data obtained from the testing will be used to identify the oxidation state of Pu(IV), Pu(V), and Pu(VI) species, which potentially could exist in caustic leachates. Work was initially conducted under contract number 24590-101-TSA-W000-00004 satisfying the needs defined in Appendix C of the Research and Technology Plan TSS A-219 to evaluate the speciation of chromium, plutonium, and manganese before and after oxidative leaching. In February 2007, the contract mechanism was switched to Pacific Northwest National Laboratory (PNNL) Operating Contract MOA: 24590-QL-HC9-WA49-00001.

  11. Development of a validated RP-LC/ESI-MS-MS method for separation, identification and determination of related substances of tamsulosin in bulk drugs and formulations.

    Science.gov (United States)

    Nageswara Rao, R; Kumar Talluri, M V N; Narasa Raju, A; Shinde, Dhananjay D; Ramanjaneyulu, G S

    2008-01-01

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method for evaluation of purity of tamsulosin in bulk drugs and pharmaceuticals was developed. The separation was accomplished on an Inertsil C(18) column using 10 mM ammonium acetate: acetonitrile as a mobile phase in a gradient elution mode. A photodiode array detector set at 280 nm was used for detection. The impurities were identified by ESI-MS-MS. The detection limits were 0.06-0.11 microg/ml. The method was validated with respect to accuracy, precision, linearity, ruggedness and limits of detection and quantification. It finds application not only for monitoring the reactions during the process development but also on quality assurance of tamsulosin.

  12. Sensory drive in cichlid speciation

    NARCIS (Netherlands)

    Maan, Martine E.; Hofker, Kees D.; van Alphen, Jacques J. M.; Seehausen, Ole

    2006-01-01

    The role of selection in speciation is a central yet poorly understood problem in evolutionary biology. The rapid radiations of extremely colorful cichlid fish in African lakes have fueled the hypothesis that sexual selection can drive species divergence without geographical isolation. Here we prese

  13. A validated stability-indicating LC method for estimation of etoposide in bulk and optimized self-nano emulsifying formulation: Kinetics and stability effects.

    Science.gov (United States)

    Akhtar, Naseem; Talegaonkar, Sushama; Khar, Roop Kishan; Jaggi, Manu

    2013-01-01

    The present investigation was aimed to establish a validated stability-indicating liquid chromatographic method for the estimation of etoposide (ETP) in bulk drug and self-nano emulsifying formulation. ETP was successfully separated from the degradation products formed under stress conditions on LiChrospher 100 C18 reverse-phase column (a 250 mm × 4.6 mm i.d., 5-μm particle size) using 55:45 (v/v) acetonitrile-phosphate buffer saline (pH 4.5) as the mobile phase, at a flow rate of 1.0 mL min(-1) and detection at 283 nm. The response was a linear function of analyte concentration (R(2) > 0.9997) over the concentration range of 0.05-50 μg mL(-1). The method was validated for precision, accuracy, robustness, sensitivity and specificity. The % recovery of ETP at three different levels (50%, 100% and 150%) ranged between 93.84% and 100.06% in optimized self-nano emulsifying formulation, Etosid® soft-gelatin capsule and Fytosid® injection. First-order degradation kinetics of ETP were observed under acidic and alkaline conditions. The method was also applied for the stability assessment of self-nano emulsifying formulation under accelerated conditions, the formulation was found to be stable at all storage conditions with the shelf-life of 2.37 years at 25 °C. The method holds promise for routine quality control of ETP in bulk, pharmaceutical formulations as well as in stability-indicating studies.

  14. Models of speciation: where are we now?

    Science.gov (United States)

    Gavrilets, Sergey

    2014-01-01

    Theory building is an integral part of biological research, in general, and of speciation research, in particular. Here, I review the modeling work on speciation done in the last 10 years or so, assessing the progress made and identifying areas where additional effort is required. Specific topics considered include evolutionary dynamics of genetic incompatibilities, spatial and temporal patterns of speciation, links to neutral theory of biodiversity, effects of multidimensionality of phenotype, sympatric and parapatric speciation, adaptive radiation, speciation by sexual conflict, and models tailored for specific biological systems. Particularly challenging questions for future theoretical research identified here are 1) incorporating gene regulatory networks in models describing accumulation of genetic incompatibilities; 2) integrating models of community ecology with those developed in speciation theory; 3) building models providing better insights on the dynamics of parapatric speciation; 4) modeling speciation in multidimensional ecological niches with mating preferences based on multidimensional mating cues and sexual characters; 5) linking microevolutionary processes with macroevolutionary patterns as observed in adaptive radiations and paleontological record; 6) modeling speciation in specific systems studied by empirical biologists; and 7) modeling human origins. The insights from dynamic models of speciation should be useful in developing statistical tools that would enable empiricists to infer the history of past evolutionary divergence and speciation from genomic data.

  15. A Validated New Gradient Stability-Indicating LC Method for the Analysis of Doripenem in Bulk and Injection Formulation

    Directory of Open Access Journals (Sweden)

    Singaram Kathirvel

    2013-01-01

    Full Text Available A sensitive, precise, specific, linear, and stability-indicating gradient HPLC method was developed for the estimation of doripenem in active pharmaceutical ingredient (API and in injectable preparations. Chromatographic separation was achieved on C18 stationary phase with a mobile phase gradient consisting of acetonitrile, methanol, and pH 5.2 phosphate buffer. The mobile phase flow rate was 0.8 mL/min, and the eluted compounds were monitored at 210 nm. The method is linear over the range of 0.335 to 76.129 µg/mL. The correlation coefficient was found to be 0.999. The numbers of theoretical plates and tailing factor for doripenem were 53021 and 0.9, respectively. Doripenem was subjected to the International Conference on Harmonization (ICH prescribed hydrolytic (acid, base, and neutral, oxidative, photolytic, and thermal stress conditions. Among all the above-mentioned conditions, the drug was found to be stable under photolytic degradation. Peak homogeneity data for doripenem in the chromatograms from the stressed samples obtained by use of the photodiode array detector demonstrated the specificity of the method for analysis of doripenem in presence of the degradation products. The performance of the method was validated according to the present ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, and robustness.

  16. Characteristics of a Bulk High-Critical Temperature Superconductor Fabricated by the Shock Compaction Method: Possible Use as a Highly Sensitive Magnetic Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, H [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Maeji, Y [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Yamagata, K [Relia. Eval. Technol. Center, Nitto Denko Corp., Onomichi, Hiroshima 722-0212 (Japan); Itoh, M [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Kezuka, H [Faculty of Bionics, Tokyo University of Technol., Hachioji, Tokyo 192-0982 (Japan); Kikuchi, M [Kansen Fukushi Research Center, Tohoku Fukushi University Sendai, Miyagi 989-3201 (Japan); Atou, T [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan); Kawasaki, M [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan); Fukuoka, K [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan)

    2006-06-01

    A magnetic sensor, constructed of bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO), was fabricated by use of the shock compaction method, employing a propellant gun-system, and then sintered under through use of an electronic furnace. The specimen as a magnetic sensor was maintained in the superconducting state at 77.4 K, under a current density J of approximately 40 A/cm{sup 2} in the absence of an excitation magnetic field B{sub ex}. The superconducting state was then broken and the specimen exposed to a B{sub ex} value of 40x10{sup -4} T. That is, the resistance R{sub meas} of the specimen occurred when exposed to 40x10{sup -4} T under a constant J of 40 A/cm{sup 2}. The magnetic sensitivity S of the specimen was approximately 13 %/(10{sup -4} T) over the range of measurement of the magnetic field B{sub meas} from 0 to {+-}5x10{sup -4} T, under a constant 40x10{sup -4} T for the value of B{sub ex}, being approximately 13 times greater than that of a giant magnetoresistance (GMR) sensor. It was, consequently, determined that it was possible to apply the bulk BPSCCO specimen as a highly sensitive magnetic sensor.

  17. Cosmic bulk flows on 50 {h}^{-1}$Mpc scales: A Bayesian hyper-parameter method and multi-shells likelihood analysis

    CERN Document Server

    Ma, Yin-Zhe

    2012-01-01

    It has been argued recently that the galaxy peculiar velocity field provides evidence of excessive power on scales of $50\\hmpc$, which seems to be inconsistent with the standard $\\Lambda$CDM cosmological model. We discuss several assumptions and conventions used in studies of the large-scale bulk flow to check whether this claim is robust under a variety of conditions. Rather than using a composite catalogue we select samples from the SN, ENEAR, SFI++ and A1SN catalogues, and correct for Malmquist bias in each according to the IRAS PSCz density field. We also use slightly different assumptions about the small-scale velocity dispersion and the parameterisation of the matter power spectrum when calculating the variance of the bulk flow. By combining the likelihood of individual catalogues using a Bayesian hyper-parameter method, we find that the joint likelihood of the amplitude parameter gives $\\sigma_8=0.65^{+0.47}_{-0.35}(\\pm 1 \\sigma)$, which is entirely consistent with the $\\Lambda$CDM model. In addition, ...

  18. Slit beam shaping method for femtosecond laser direct-write fabrication of symmetric waveguides in bulk glasses

    Science.gov (United States)

    Ams, Martin; Marshall, G. D.; Spence, D. J.; Withford, M. J.

    2005-07-01

    We report both theoretical and experimental results of a slit beam shaping configuration for fabricating photonic waveguides by use of femtosecond laser pulses. Most importantly we show the method supports focusing objectives with a long depth of field and allows the direct-writing of microstructures with circular cross-sections whilst employing a perpendicular writing scheme. We applied this technique to write low loss (0.39 dB/cm), single mode waveguides in phosphate glass.

  19. Bulk characterization of pharmaceutical powders by low-pressure compression II: effect of method settings and particle size.

    Science.gov (United States)

    Sørensen, Arne Hagsten; Sonnergaard, Jørn Møller; Hovgaard, Lars

    2006-01-01

    The aim of the present study was to investigate the effect of punch and die diameter, sample size, compression speed, and particle size on two low-pressure compression-derived parameters; the compressed density and the Walker w parameter. The excellent repeatability of the low-pressure compression method allowed small effects of variations in punch and die diameter and sample size to be demonstrated on a high significance level. Changing the compression speed, however, did not cause a significant effect in the compressed density, whereas a decrease in w was seen. The effect of particle size was studied by compressing and tapping different grades of calcium carbonate, lactose, and microcrystalline cellulose. The low-pressure compression-derived parameters were compared to tapped densities and to Compressibility Indexes obtained by tapping volumetry. Even though the relationship between particle size and the low-pressure compression-derived parameters appeared to be more complicated, a similar trend was observed. It was concluded that the low-pressure compression method provides a useful alternative to the more sample-consuming methods providing flow-related information.

  20. Sensitive method for rapid estimation of Lornoxicam in bulk and its dosage form by RP-HPLC

    Institute of Scientific and Technical Information of China (English)

    Prajapati Prajesh; Vaghela Vipul; Baraiya Dharmendra

    2013-01-01

    Lornoxicam (6-chloro-4-hydroxy-2-methyl-N-2-pyridyl-2H-thieno-[2,3-e]-1,2-thiazine-3-carboxamide-1,1-dioxide)is persist as a non-steroidal anti-inflammatory drug of the oxicam class with analgesic,anti-inflammatory and antipyretic properties.A fast,accurate and sensitive chromatographic method for estimation of Lomoxicam was developed as no official method available for detection.The chromatographic separation employs isocratic elution by utilizing an inertsil ODS-C18,250 mm×4.6 mm,5 μm columns.Mobile phase consisting of solvent (40 mL acetonitrile and 60 mL 0.1 M phosphate buffer (pH 6.8 was adjusted with triethylamine)) endowed at a flow rate of 1.0 mL/min.The analyte was detected and quantified at 290 nm using UV detector.The method was validated according to ICH guidelines,illustrating to be accurate (recovery 99.08%-101.13%) and precise (intraday (0.27-1.32) and interday (0.59-1.59))within the corresponding linear range (10-60 μg/mL) with r2 0.9992.

  1. Mercury speciation analysis in terrestrial animal tissues.

    Science.gov (United States)

    Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C; Guzmán Bernardo, F J; Rodríguez Fariñas, N; Patiño Ropero, M J

    2012-09-15

    No previous analytical procedures are available and validated for mercury speciation analysis in terrestrial animal tissues. This analysis is a difficult task both because the expected concentrations are low, since important accumulation process are not likely to occur, and also because there are not commercially available certified reference material. Thus, an analytical methodology has been developed and validated for mercury speciation for the specific case of terrestrial animal tissues. The proposed method is based on the quantitative extraction of the species by closed-vessel microwave assisted heating with an alkaline reagent, followed by ethylation. The ethylated derivatives were then submitted to head-space solid phase microextraction with a 100 μm polidimethylsiloxane-coated fiber, and desorbed onto a gas chromatograph coupled to atomic fluorescence detection via pyrolysis unit (HS-SPME-GC-pyro-AFS). Procedural detection limits were 31.8 ng g(-1) and 52.5 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for liver and 35.3 ng g(-1) and 58.1 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for kidney. These limits of detection are 5.5 and 6 times better than the obtained without solid phase microextraction for CH(3)Hg(+) and Hg(2+), respectively. The methodology was found linear up to 120 μg L(-1) and reproducible from one day to the following. It was validated with certified reference materials NCS ZC 71001 (beef liver) and BCR No 186 (pig kidney) for total mercury, calculated as the sum of species, and with spiked red deer liver and kidney for speciation. Finally, it was applied to the analysis of samples of red deer liver, red deer kidney and wild boar kidney coming from the Almadén's mercury mining area (Ciudad Real, Spain), the longest and largest producer of mercury in the world until its closure in 2002.

  2. DEVELOPMENT AND VALIDATION OF A RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF PROPRANOLOL HCl AND CLONAZEPAM IN BULK AND PHARMACEUTICAL DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Tanikella Sai Annapurneswari

    2012-09-01

    Full Text Available The present work describes a reverse phase high performance liquid chromatographic method (RP-HPLC for the simultaneous estimation of Propranolol HCl (PRH and Clonazepam (CNZ in bulk and in pharmaceutical dosage form. Chromatographic separation was performed on Agilent Eclipse xdb C18 (150 mm  4.6 mm i.d., 5 m column, with a mobile phase comprising of a mixture of methanol, acetonitrile and 20 mM potassium dihydrogen phosphate buffer in the ratio of 27.5:27.5:45 v/v. The pH of buffer was adjusted to 3.0 with orthophosphoric acid. The flow rate was 1.0 ml/min with detection at 266 nm. Retention times of Propranolol HCl and Clonazepam were found to be 2.400 and 4.492 min respectively. As per International Conference on Harmonisation (ICH guidelines the method was validated for linearity, accuracy, precision, limit of quantitation, limit of detection, and robustness. Linearity of PRH was found to be in the range of 20-120 µg/mL and that for CNZ was found to be 1-6 µg/mL. The correlation coefficients were 0.9994 and 0.9995 for PRH and CNZ respectively. The mean recoveries obtained for PRH and CNZ were 100.6% and 100.1%. This demonstrates that the developed method is simple, precise, accurate, reproducible and rapid for simultaneous estimation of these drugs in bulk and in tablet dosage forms.

  3. Practical Implication of Chromatographic Method for Estimation of Aceclofenac and Pregabalin in Bulk and Pharmaceutical Dosage Forms

    Directory of Open Access Journals (Sweden)

    Hitendrakumar D. Gelani

    2014-01-01

    Full Text Available Background. Aceclofenac and Pregabalin in combination significantly reduce pain as compared to individual drug in chronic low back pain. Literature reveals that all the reported spectrophotometric methods either need tedious extraction procedures, do not offer high sensitivity, use nonspecific reagent, or recommend the measurement of absorbance in the near UV region where interference most probably occurs that does not offer suitable linearity range. Result. A selective, sensitive, accurate, and precise, high performance liquid chromatographic method with UV detector analysis of Aceclofenac and Pregabalin was investigated. Good chromatographic separation was achieved using an ODS-BP hypersil C18 column (250 mm × 4.6 mm, i.d., 5 μm and a mobile phase consisting of 0.05 M phosphate buffer (KH2PO4 (pH 6.0 : methanol (60 : 40, v/v at a flow rate 1 mL/min. The ultraviolet detector was set at wavelength 218 nm. Retention time for Aceclofenac and Pregabalin was found to be 3.220 and 5.910 min, respectively. Rectilinear relationship with good regression coefficients 0.999 and 0.999 was found over the concentration ranges of 5–25 μg/mL and 3.75–18.75 μg/mL for ACF and PGB, respectively, with detection limits 0.64 and 0.35 μg/mL and quantitation limits 1.95 and 1.06 μg/mL. Conclusion. The mean percentage recoveries were in the range of 98.45–100.08 and 99.69–100.48 for ACF and PGB, respectively. The developed method was successfully applied to the analysis of the drugs in their commercial tablets.

  4. A validated stability-indicating normal phase LC method for clopidogrel bisulfate and its impurities in bulk drug and pharmaceutical dosage form.

    Science.gov (United States)

    Durga Rao, Dantu; Kalyanaraman, L; Sait, Shakil S; Venkata Rao, P

    2010-05-01

    A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of clopidogrel drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of clopidogrel along with the chiral impurities. This method can be also be used for the estimation of assay of clopidogrel in drug substance as well as in drug product. The method was developed using Chiralcel OJ-H (250mmx4.6mm, 5microm) column. n-Hexane, ethanol and diethyl amine in 95:5:0.05 (v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 240nm. Clopidogrel bisulfate was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability.

  5. DEVELOPMENT AND VALIDATION OF A NEW HPLC METHOD FOR THE ESTIMATION OF AZITHROMYCIN IN BULK AND TABLET DOSAGE FORM

    OpenAIRE

    Irin Dewan*, T. Amin , Md. F. Hossain , M. Hasan , S. F. Chowdhury , M. Gazi and S.M. Ashraful Islam

    2013-01-01

    A simple, reproducible and efficient reversed phase high performance liquid chromatographic (RP-HPLC) method has been developed for quantitative determination of azithromycin in drug substance. The separations were carried out on a Xterra C18 column (150 ×4.6 mm; 5µ) with UV detection at 215 nm. The mobile phase consisting of acetonitrile and phosphate buffer (pH adjusted to 7.5) in a ratio of 50:50 v/v. The injection volume was 50 µl and flow rate was 1.0 mL/min. The linear dynamic response ...

  6. Mineralogy and metals speciation in Mo rich mineral sludges generated at a metal recycling plant.

    Science.gov (United States)

    Vemic, M; Bordas, F; Guibaud, G; Joussein, E; Labanowski, J; Lens, P N L; van Hullebusch, E D

    2015-04-01

    In France, more than 250 million metric tons of sludges need to be treated each year. These sludges are either dumped on the landfills or reused as secondary resources in order to preserve natural resources. A large portions of these sludges are mineral sludges, originating from metal recycling plants. In order to estimate their metal recovery potential, these mineral sludges were characterized. Four types of mineral sludge samples were collected from a metal recycling plant (3 from the recycling plant storage areas (bulk storage, barrel storage and storage shed) and 1 from the collection basin). The sludges were characterized, wherein the Mo, Ni, Cr, Co, Zn and W content and speciation were quantified. The samples had pH values between 5.9 and 10.3 with organic matter contents varying between 6.3% (storage shed) and 29.5% (bulk storage) (loss on ignition at 500 °C). Based on their leaching properties, the four mineral sludge samples (in the case of Mo) and the bulk storage sludge (in the case of Ni and Zn) were classified as potentially hazardous regarding the EN 12457-1 and EN 12457-2 method. Mineralogical results reveal that both bulk storage and the storage shed give the highest contributions to the metal content of the collection basin sample. Sequential extraction of the collection basin samples indicated that Mo is bound to the oxidizable and residual fraction, while Ni, Cr and Co were bound to the residual fraction, and Zn to the soluble acid fraction, respectively. W tends to be equally distributed among all extracted fractions. A strong correlation existed between Mo and Co, as well as between Ni, Zn and Cr, respectively.

  7. Stability-indicating liquid chromatographic method for quantification of new anti-epileptic drug lacosamide in bulk and pharmaceutical formulation

    Directory of Open Access Journals (Sweden)

    Chhalotiya Usmangani K.

    2012-01-01

    Full Text Available An isocratic stability indicating reversed-phase liquid chromatographic determination was developed for the quantitative determination of lacosamide in the pharmaceutical dosage form. A Hypersil C-18, 4.5μm column with mobile phase containing acetonitrile-water (20:80, v/v was used. The flow rate was 1.0 mL min-1 and effluents were monitored at 258 nm. The retention time of lacosamide was 8.9 min. The method was found to be linear in the concentration range of 5-100 μg/ml and the recovery was found to be in the range of 99.15 - 100.09 %. The limit of detection and limit of quantification were found to be 2 μg/ml and 5 μg/ml, respectively. Lacosamide stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The drug was found to be stable to the dry heat and acidic condition attempted. The proposed method was validated and successfully applied to the estimation of lacosamide in tablet dosage forms.

  8. Bulk growth of ninhydrin single crystals by solvent evaporation method and its characterization for SHG and THG applications

    Science.gov (United States)

    Vijayan, N.; Philip, J.; Haranath, D.; Rathi, Brijesh; Bhagavannarayana, G.; Halder, S. K.; Roy, N.; Jayalakshmy, M. S.; Verma, Sunil

    2014-03-01

    Ninhydrin is a well-known compound generally used in amino acid synthesis and also for detecting the latent fingerprints on porous surfaces. Single crystals can be grown by dissolving the compound in double distilled water at ambient temperature, and can be used as a potential material for second and third harmonic generation applications. The grown specimen was subjected to different characterization techniques in order to find out its suitability for device fabrication. Its lattice dimensions have been confirmed by X-ray powder diffraction and its crystalline quality has been assessed by high resolution X-ray diffraction and X-ray topography methods. The presence of functional groups was identified from HETCOR analysis and confirmed the absence of impurities during crystallization. Its optical properties have been examined by photoluminescence and birefringence analyses. Its thermal parameters such as thermal diffusivity, thermal conductivity and specific capacity have been carried out by following photopyroelectric method. Third order nonlinear optical measurements have been carried out using Z-scan technique and its nonlinear optical absorption coefficient has been determined.

  9. Development and validation of UV-spectrophotometric methods for the determination of sumatriptan succinate in bulk and pharmaceutical dosage form and its degradation behavior under varied stress conditions

    Directory of Open Access Journals (Sweden)

    Kudige Nagaraj Prashanth

    2014-04-01

    Full Text Available The aim of the present work is to develop sensitive, simple, accurate, precise and cost effective UV-spectrophotometric methods for the determination of sumatriptan succinate (STS, an anti-migraine drug, in bulk and pharmaceutical dosage form; and also to monitor the degradation behavior of the drug under different ICH prescribed stress conditions. Two methods were developed using different solvents, 0.1 M HCl (method A and acetonitrile (method B. The calibration graphs are linear over the range of 0.2–6.0 μg ml−1 in both the methods with a correlation coefficient (r of 0.9999. The apparent molar absorptivity values are 7.59 × 104 and 7.81 × 104 l mol−1 cm−1, for method A and method B, respectively. The other optical characteristics such as Sandell’s sensitivity, limit of detection (LOD and limit of quantification (LOQ values are also reported. The accuracy and precision of the methods were evaluated based on intra-day and inter-day variations. The accuracy of the methods was further confirmed by standard addition procedure. The degradation behavior of the drug was studied by subjecting STS to an acid and alkaline hydrolysis, oxidative, thermal and UV degradation. This study indicated that STS was degraded in alkaline medium and in oxidative condition. The proposed methods were successfully applied to the determination of STS in tablets and the results obtained are comparable with the official method.

  10. Speciation and migration of 129I in soil profiles

    DEFF Research Database (Denmark)

    Luo, Maoyi; Hou, Xiaolin; Zhou, Weijian;

    2013-01-01

    A method has been developed for speciation analysis of ultra low level 129I in soil using sequential extraction combined with coprecipitation for separation of carrier free iodine and AMS measurement of 129I. Two loess profiles collected from northwest China were analyzed for species of 129I...

  11. Extractive spectrophotometric methods for the determination of oxomemazine hydrochloride in bulk and pharmaceutical formulations using bromocresol green, bromocresol purple and bromophenol blue.

    Science.gov (United States)

    El-Didamony, Akram M

    2005-04-01

    Three simple, sensitive and accurate spectrophotometric methods have been developed for the determination of oxomemazine hydrochloride in bulk and pharmaceutical formulations. These methods are based on the formation of yellow ion-pair complexes between the examined drug and bromocresol green (BCG), bromocresol purple (BCP), and bromophenol blue (BPB) as sulphophthalein dyes in acetate-HCl buffer of pH 3.6, 3.4, and 4.0, respectively. The formed complexes were extracted with dichloromethane and measured at 405 nm for all three systems. The best conditions of the reactions were studied and optimized. Beer's law was obeyed in the concentration ranges 2.0-12, 2.0-13, and 2.0-14 microg mL(-1) with molar absorptivities of 3.2 x 10(4), 3.7 x 10(4), and 3.1 x 10(4) L mol(-1) cm(-1) for the BCG, BCP, and BPB methods, respectively. Sandell's sensitivity, correlation coefficient, detection and quantification limits are also calculated. The proposed methods have been applied successfully for the analysis of the drug in pure form and in its dosage forms. No interference was observed from common pharmaceutical excipients. Statistical comparison of the results with those obtained by HPLC method shows excellent agreement and indicates no significant difference in accuracy and precision.

  12. Development and Validation of Stability-Indicating GC-FID Method for the Quantitation of Memantine Hydrochloride and Its Nonchromophoric Impurities in Bulk and Pharmaceutical Dosages

    Directory of Open Access Journals (Sweden)

    Sanjay A. Jadhav

    2012-01-01

    Full Text Available A stability-indicating method has been developed and validated for the quantitative determination of memantine hydrochloride and its nonchromophoric impurities in drug substance and drug product using gas chromatography coupled with flame ionization detector (GC-FID. The stability-indicating nature of the method has been proved by establishing peak purity and confirming the mass balance of all samples by subjecting them to stress conditions like hydrolysis, oxidation, photolysis, and thermal degradation studies. The chromatographic separation was performed on a fused silica capillary (HP-5, 30 meter, 0.32 mm and 0.25 μm film thickness column. The method validation results indicate that the method has acceptable specificity, accuracy, linearity, precision, robustness, and high sensitivity with detection limits and quantitation limits ranging from 0.001% to 0.01% and 0.004% to 0.03%, respectively. The effectiveness of the technique was demonstrated by analysis of different bulk sample of Memantine hydrochloride. The proposed GC-FID method was also found to be specific and selective for the analysis of commercial formulation samples.

  13. A validated chiral LC method for enantiomeric separation of nebivolol stereoisomers in bulk drugs and dosage forms on amylose-based stationary phase.

    Science.gov (United States)

    Visweswara Rao, Karri; Padmaja Reddy, Kesareddy; Haldar, Pranab

    2014-10-01

    A novel and reproducible isocratic normal phase liquid chromatographic method was developed for the quantitative determination of 10 stereoisomers of Nebivolol in pharmaceutical bulk drugs and dosage forms. The method was developed using an amylose-based chiral stationary phase, Chiralpak AD-3 (250 × 4.6 mm, 3 μm) column with mobile phase containing n-hexane-ethanol-isopropanol-diethanolamine in the ratio 42:45:13:0.1 (v/v/v/v). The eluted compounds were monitored at 280 nm. Ten stereoisomers of Nebivolol were well separated with resolution >2.0 for all pair of components. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, linearity (R(2) value >0.999), limit of detection, limit of quantification, accuracy (recovery range 95.8-103.2%), precision (relative standard deviation, RSD, <2.5%) and robustness. Nebivolol sample solutions were found to be stable when characterized over a period of 48 h. Forced degradation studies were also performed to demonstrate the stability-indicating power of the developed HPLC method. The method was found to be rugged and robust.

  14. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  15. SIMULTANEOUS ESTIMATION OF FEXOFENADINE HYDROCHLORIDE AND MONTELUKAST SODIUM IN BULK DRUG AND MARKETED FORMULATION BY RP-HPLC METHOD

    Directory of Open Access Journals (Sweden)

    Ravisankar M

    2012-04-01

    Full Text Available A new simple and precise accurate RP-HPLC method has been developed and validated for simultaneous estimation of Montelukast Sodium and Fexofenadine in tablet formulations. The chromatographic separation was performed in Water symmetry C8 (150X4.6mm 5µm and mobile phase 0.05 m potassium di hydrogen ortho phosphate: acetonitrile in the ratio of 35:65 and the pH – 6 adjusted by triethylamine.The flow rate was 1.0ml/min and the wavelength selected for the quantization was 226 nm. The retention time was found to be 2.127 min for Fexofenadine and 5.650 min for Montelukast sodium .The linearity were found to be in the range of 4.8 - 28.8 µg/ml and 0.4 – 2.4 µg/ml for Fexofenadine and Montelukast respectively with the correlation co efficient of 0.999.The mean recoveries for Fexofenadine and Montelukast were 99.85 % and 100.19 % respectively, and relative standard deviation was less than 2%. Precision were performed as per ICH guidelines with the result shows relative standard deviation not more than 2%.The assay value for Fexofenadine and Montelukast were found to be 100.55 % and 100.40 % respectively.

  16. Liquid chromatographic method for the simultaneous determination of captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulation, and human serum by programming the detector.

    Science.gov (United States)

    Sultana, Najma; Arayne, M Saeed; Ali, Saeeda Nadir

    2013-10-01

    A highly sensitive LC method with UV detection has been developed for the simultaneous determination of coadministered drugs captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulations, and human serum at the isosbestic point (235 nm) and at individual λmax (220, 255, and 238 nm, respectively) by programming the detector with time to match the individual analyte's chromophore, which enhanced the sensitivity with linear range. The assay involved an isocratic elution of analytes on a Bondapak C18 (10 μm, 25 × 0.46 cm) column at ambient temperature using a mobile phase of methanol/water 80:20 at pH 2.9 and a flow rate of 1.0 mL/min. Linearity was found to be 0.25-25, 0.10-6.0, and 0.20-13.0 μg/mL with correlation coefficient >0.998 and detection limits of 7.39, 3.90, and 9.38 ng/mL, respectively, whereas calibration curves for wavelength-programmed analysis were 0.10-6.0, 0.04-2.56, and 0.10-10.0 μg/mL with correlation coefficient >0.998 and detection limits of 5.79, 2.68, and 3.87 ng/mL, respectively. All the validated parameters were in the acceptable range. The recovery of drugs was 99.32-100.39 and 98.65-101.96% in pharmaceutical formulation and human serum, respectively, at the isosbestic point and at individual λmax . This method is applicable for the analysis of drugs in bulk drug, tablets, serum, and in clinical samples without interference of excipients or endogenous serum components.

  17. Model inadequacy and mistaken inferences of trait-dependent speciation.

    Science.gov (United States)

    Rabosky, Daniel L; Goldberg, Emma E

    2015-03-01

    Species richness varies widely across the tree of life, and there is great interest in identifying ecological, geographic, and other factors that affect rates of species proliferation. Recent methods for explicitly modeling the relationships among character states, speciation rates, and extinction rates on phylogenetic trees- BiSSE, QuaSSE, GeoSSE, and related models-have been widely used to test hypotheses about character state-dependent diversification rates. Here, we document the disconcerting ease with which neutral traits are inferred to have statistically significant associations with speciation rate. We first demonstrate this unfortunate effect for a known model assumption violation: shifts in speciation rate associated with a character not included in the model. We further show that for many empirical phylogenies, characters simulated in the absence of state-dependent diversification exhibit an even higher Type I error rate, indicating that the method is susceptible to additional, unknown model inadequacies. For traits that evolve slowly, the root cause appears to be a statistical framework that does not require replicated shifts in character state and diversification. However, spurious associations between character state and speciation rate arise even for traits that lack phylogenetic signal, suggesting that phylogenetic pseudoreplication alone cannot fully explain the problem. The surprising severity of this phenomenon suggests that many trait-diversification relationships reported in the literature may not be real. More generally, we highlight the need for diagnosing and understanding the consequences of model inadequacy in phylogenetic comparative methods.

  18. DEVELOPMENT AND VALIDATION OF STABILITY INDICATING RP- HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF AMLODIPINE AND LOSARTAN IN BULK DRUG AND TABLET DOSAGE FORMULATION

    Directory of Open Access Journals (Sweden)

    Ramya Gavini

    2012-11-01

    Full Text Available A simple, precise and stability indicating reversed phase liquid chromatographic method was developed and validated for simultaneous estimation of Amlodipine and Losartan potassium in bulk and tablet formulation. The separation was achieved on Enable C18 G (250mm x 4.6mm, 5µm analytical column with mobile phase comprising of 0.005M Potassium dihydrogen phosphate: Acetonitrile (pH 3.0 (50:50v/v at isocratic flow of 1.0ml/min with UV detection at 230 nm. The retention times of amlodipine and losartan potassium was found to be 4.3 and 6.7 minutes respectively. The method was successfully validated in accordance with ICH guidelines for different validation parameters using PDA detector. The linear regression analysis data for calibration plots showed good linear relationship in the concentration range 0.125-0.75 μg/mL for amlodipine and 1.25-7.5 μg/mL for losartan potassium. The drugs were exposed to acidic, basic, oxidation, thermal and photolytic stress degradation conditions and the resultant stressed samples were analyzed by the proposed method and was established to provide high resolution among the degradation products and the analytes. The method could effectively separate the drug from its degradation product; hence it can be employed as a stability- indicating one.

  19. NICKEL SPECIATION OF URBAN PARTICULATE MATTER

    Energy Technology Data Exchange (ETDEWEB)

    Kevin C. Galbreath; Charlene R. Crocker; Carolyn M. Nyberg; Frank E. Huggins; Gerald P. Huffman

    2003-10-01

    A four-step sequential Ni extraction method, summarized in Table AB-1, was evaluated for identifying and quantifying the Ni species occurring in urban total suspended particulate (TSP) matter and fine particulate matter (<10 {micro}m [PM{sub 10}] and <2.5 {micro}m [PM{sub 2.5}] in aerodynamic diameter). The extraction method was originally developed for quantifying soluble, sulfidic, elemental, and oxidic forms of Ni that may occur in industrial atmospheres. X-ray diffraction (XRD) and x-ray absorption fine structure (XAFS) spectroscopy were used to evaluate the Ni species selectivity of the extraction method. Uncertainties in the chemical speciation of Ni in urban PM{sub 10} and PM{sub 2.5} greatly affect inhalation health risk estimates, primarily because of the large variability in acute, chronic, and cancer-causing effects for different Ni compounds.

  20. Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials.

    Science.gov (United States)

    Mulugeta, Mesay; Wibetoe, Grethe; Engelsen, Christian J; Lund, Walter

    2010-10-01

    A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 μg/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates.

  1. MODELING MONOMETHYLMERCURY AND TRIBUTYLTIN SPECIATION WITH EPA'S GEOCHEMICAL SPECIATION MODEL MINTEQA2

    Science.gov (United States)

    Given the complexity of the various, simultaneous (and competing) equilibrium reactions governing the speciation of ionic species in aquatic systems, EPA has developed and distributed the geochemical speciation model MINTEQA2 (Brown and Allison, 1987, Allison et al., 1991; Hydrog...

  2. Speciation in fungal and oomycete plant pathogens.

    Science.gov (United States)

    Restrepo, Silvia; Tabima, Javier F; Mideros, Maria F; Grünwald, Niklaus J; Matute, Daniel R

    2014-01-01

    The process of speciation, by definition, involves evolution of one or more reproductive isolating mechanisms that split a single species into two that can no longer interbreed. Determination of which processes are responsible for speciation is important yet challenging. Several studies have proposed that speciation in pathogens is heavily influenced by host-pathogen dynamics and that traits that mediate such interactions (e.g., host mobility, reproductive mode of the pathogen, complexity of the life cycle, and host specificity) must lead to reproductive isolation and ultimately affect speciation rates. In this review, we summarize the main evolutionary processes that lead to speciation of fungal and oomycete plant pathogens and provide an outline of how speciation can be studied rigorously, including novel genetic/genomic developments.

  3. Development and validation of a liquid chromatographic method for the simultaneous determination of aniracetam and its related substances in the bulk drug and a tablet formulation.

    Science.gov (United States)

    Papandreou, Georgios; Zorpas, Kostas; Archontaki, Helen

    2011-11-01

    Simultaneous determination of aniracetam and its related impurities (2-pyrrolidinone, p-anisic acid, 4-p-anisamidobutyric acid and (p-anisoyl)-4-methyl-2-pyrrolidinone) was accomplished in the bulk drug and in a tablet formulation using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS-CN column (150 mm × 4.0 mm, 5 μm) using a gradient elution program with solvent A composed of phosphate buffer (pH 4.0; 0.010 M) and solvent B of acetonitrile-phosphate buffer (pH 4.0; 0.010 M) (90:10, v/v). The flow rate of the mobile phase was 1.0 mL min(-1) and the total elution time, including the column re-equilibration, was approximately 20 min. The UV detection wavelength was varied appropriately among 210, 250 and 280 nm. Injection volume was 20 μL and experiments were conducted at ambient temperature. The developed method was validated in terms of system suitability, selectivity, linearity, range, precision, accuracy, limits of detection and quantification for the impurities, short term and long term stability of the analytes in the prepared solutions and robustness, following the ICH guidelines. Therefore, the proposed method was suitable for the simultaneous determination of aniracetam and its studied related impurities.

  4. Stability indicating method development and validation for simultaneous estimation of atorvastatin calcium and celecoxib in bulk and niosomal formulation by RP-HPLC

    Directory of Open Access Journals (Sweden)

    Priyanka S. Jadhav

    2015-09-01

    Full Text Available The present work describes development and validation of a specific, sensitive, precise and stability-indicating high-performance liquid chromatographic method of analysis of atorvastatin calcium and celecoxib, both as a bulk drug and in niosomal formulation. The analysis has been performed by using Cosmosil-C18 column (4.6 mm´250 mm, 5 m at 25 °C using acetonitrile: ammonium acetate buffer pH 5.0: methanol (50:25:25 v/v/v as mobile phase. The detection was carried out at 277nm with a flow rate of 1.0mL/min. The retention times of Atorvastatin calcium and Celecoxib were 6.195 and 3.989min, respectively. The method was validated according to ICH guidelines, for specificity, precision, linearity, accuracy and robustness. Atorvastatin calcium and Celecoxib were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The degradation was observed in oxidation and acid hydrolysis. The linearity for atorvastatin calcium and celecoxib were in the range of 100-500 µg/mL. The recovery study of atorvastatin and celecoxib were found to be in the range of 98.96 - 99.92% and 98.90-100%, respectively. The proposed method was validated and successfully applied to the estimation of Atorvastatin calcium and Celecoxib in combined in-house niosomal formulation.

  5. Forced degradation study to develop and validate stability-indicating RP-LC method for the determination of ciclesonide in bulk drug and metered dose inhalers.

    Science.gov (United States)

    Elkady, Ehab F; Fouad, Marwa A

    2011-12-15

    A simple, selective and precise stability-indicating reversed-phase liquid chromatographic method was developed and validated for the determination of ciclesonide. Ciclesonide was subjected to acid and alkali hydrolysis, oxidation, thermal and photo-degradation. The degradation products were well separated from the pure drug. The method was based on isocratic elution of ciclesonide and its degradation products on reversed phase C18 column (250 mm × 4.6 mm, 10 μm) - Phenomenex using a mobile phase consisting of ethanol-water (70:30, v/v) at a flow rate of 1 mL min(-1). Quantitation was achieved with UV detection at 242 nm. Linearity, accuracy and precision were found to be acceptable over the concentration range of 5-200 μg mL(-1). Desisobutyryl-ciclesonide was prepared by selective alkaline hydrolysis of the ester and proved to be the main degradation product. The proposed method was successfully applied to the determination of ciclesonide in bulk and in its pharmaceutical preparation.

  6. Application of experimental design for the optimization of forced degradation and development of a validated stability-indicating LC method for luliconazole in bulk and cream formulation

    Directory of Open Access Journals (Sweden)

    Sandeep Sonawane

    2016-11-01

    Full Text Available A stability-indicating LC method was developed and validated for the determination of luliconazole in bulk and cream formulation. Luliconazole was exposed to acid, alkali and water hydrolysis, oxidation effect by hydrogen peroxide, dry heat and photolytic conditions. Full factorial design was used during forced degradation experiments and the factors/combination of factors which were most likely to effect degradation of luliconazole under various conditions were identified and further were optimized using surface response curve. Drug was found to be stable under wet heat and dry heat conditions, but substantial degradation was observed under acid, alkali, oxidative and photolytic conditions. Drug and its degradation products were optimally resolved on HiQ sil C-18HS (250 × 4.6 mm, 5 μm column with the mobile phase consisting of methanol and water (80:20, v/v at a flow rate of 1 mL/min, detection was performed at 296 nm. The procedure was validated for specificity, linearity, accuracy and precision. There was no interference of excipients and degradation products in the determination of active pharmaceutical ingredient. The method was accurate and precise and the response was found to be linear in the range of 2–14 μg/mL. The method was found to be simple and fast by making use of experimental design.

  7. Speciation of Black-necked Crane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the concepts of species and speciation,the speciation of Black-necked Grane(Grus nigricollis) was discussed using bio-geographic principles and some evidences suggest that Black-necked Grane had a close relationship with Red-crowned Crane(Grus japonensis).The Qinghai-Tibetan Plateau uplift may be the most important factor in allopatric speciation for Black-necked Crane.

  8. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    Energy Technology Data Exchange (ETDEWEB)

    Beinhauer, Jana [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Bian, Liangqiao [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Fan, Hui [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Šebela, Marek [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Kukula, Maciej [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Barrera, Jose A. [Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); and others

    2015-02-09

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL{sup −1}, and demonstrated good linearity of R{sup 2} from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL{sup −1}. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.

  9. Speciation and release kinetics of cadmium in an alkaline paddy soil under various flooding periods and draining conditions.

    Science.gov (United States)

    Khaokaew, Saengdao; Chaney, Rufus L; Landrot, Gautier; Ginder-Vogel, Matthew; Sparks, Donald L

    2011-05-15

    This study determined Cd speciation and release kinetics in a Cd-Zn cocontaminated alkaline paddy soil, under various flooding periods and draining conditions, by employing synchrotron-based techniques, and a stirred-flow kinetic method. Results revealed that varying flooding periods and draining conditions affected Cd speciation and its release kinetics. Linear least-squares fitting (LLSF) of bulk X-ray absorption fine structure (XAFS) spectra of the air-dried, and the 1 day-flooded soil samples, showed that at least 50% of Cd was bound to humic acid. Cadmium carbonates were found as the major species at most flooding periods, while a small amount of cadmium sulfide was found after the soils were flooded for longer periods. Under all flooding and draining conditions, at least 14 mg/kg Cd was desorbed from the soil after a 2-hour desorption experiment. The results obtained by micro X-ray fluorescence (μ-XRF) spectroscopy showed that Cd was less associated with Zn than Ca, in most soil samples. Therefore, it is more likely that Cd and Ca will be present in the same mineral phases rather than Cd and Zn, although the source of these two latter elements may originate from the same surrounding Zn mines in the Mae Sot district.

  10. Validated stability-indicating high performance thin layer chromatographic method for determination of Ivabradine hydrochloride in bulk and marketed formulation: An application to kinetic study

    Directory of Open Access Journals (Sweden)

    Mitesh H. Motisariya

    2013-12-01

    Full Text Available A sensitive, selective, precise and accurate stability-indicating high-performance thin layer chromatographic method for analysis of Ivabradine hydrochloride (IH an anti anginal agent, both as a bulk drug and in formulations was developed and validated according to ICH guideline. Densitometric analysis of IH was carried out in the absorbance mode at 287 nm using ethyl acetate: 0.389 M ammonium acetate in methanol (1:5, v/v as solvent system. This system was found to give compact spots for IH at an Rf value of 0.36 ± 0.01. Moreover, IH was subjected to acid and alkali hydrolysis, oxidation, accelerated humidity/temperature, wet heat treatment, and photo degradation. The drug undergoes degradation under mainly acidic and basic conditions. Also the degraded products were well resolved from the pure drug with significantly different Rf values. Linearity was found to be in the range of 1200–2800 ng/band. The LOD and LOQ for IH were 255.86 ng/band and 775.33 ng/band, respectively. “Bartlett’s test” and “Lack of fit” applied on peak area for linearity, additionally proved validity of the developed method. Good accuracy and precision were obtained as revealed from %RSD value less than 2. Similarly, no interference was observed from common excipients in tablet formulation as well as degradation product, indicating specificity of the method. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one. Moreover, proposed method was also utilized to investigate the kinetics of acidic degradation process at different temperatures and first order rate constant, half-life, shelf-life and activation energy were calculated.

  11. USE OF MICRO X-RAY ABSORPTION SPECTROSCOPY AND DIFFRACTION TO DELINEATE Cr(VI) SPECIATION IN COPR

    Energy Technology Data Exchange (ETDEWEB)

    CHRYSOCHOOU, M.; MOON, D. H.; FAKRA, S.; MARCUS, M.; DERMATAS, D.; CHRISTODOULATOS, C.

    2010-06-22

    The speciation of Cr(VI) in Cromite Ore Processing Residue was investigated by means of bulk XRD, and a combination of micro-XRF, -XAS and -XRD at the Advanced Light Source (ALS), Berkeley, CA, U.S.A.. Bulk XRD yielded one group of phases that contained explicitly Cr(VI) in their structure, Calcium Aluminum Chromium Oxide Hydrates, accounting for 60% of the total Cr(VI). Micro-analyses at ALS yielded complimentary information, confirming that hydrogarnets and hydrotalcites, two mineral groups that can host Cr(VI) in their structure by substitution, were indeed Cr(VI) sinks. Chromatite (CaCrO4) was also identified by micro-XRD, which was not possible with bulk methods due to its low content. The acquisition of micro-XRF elemental maps enabled not only the identification of Cr(VI)-binding phases, but also the understanding of their location within the matrix. This information is invaluable when designing Cr(VI) treatment, to optimize release and availability for reduction.

  12. Development and validation of a simple stability-indicating high performance liquid chromatographic method for the determination of miconazole nitrate in bulk and cream formulations.

    Science.gov (United States)

    De Zan, María M; Cámara, María S; Robles, Juan C; Kergaravat, Silvina V; Goicoechea, Héctor C

    2009-08-15

    A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB - C18 (4.6 mm x 150 mm, 5 microm particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 degrees C and 10 microL of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis.

  13. DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF GLIPIZIDE AND METFORMIN IN BULK DRUGS AND TABLET DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    D.Triveni

    2012-09-01

    Full Text Available The present work describes development and validation of simple, precise and accurate reversed-phase liquid chromatographic method for simultaneous estimation of glipizide and metformin hydrochloride in both bulk drugs and pharmaceutical dosage forms. The chromatographic separation was achieved on (Enable, symmetry C18, 250mm x 4.6mm, 5μ analytical column. A mobile phase consisting mixture of potassium dihydrogen phosphate (0.2M, pH 5.8 adjusted with dilute sodium hydroxide and acetonitrile in ratio (60:40 v/v at flow rate of 1.0ml/min and UV detector wavelength 258 nm. The retention time of glipizide and metformin Hcl was found to be 7.9 and 2.5 minutes respectively.The method was successfully validated in accordance to ICH guidelines for accuracy, precision, specificity, linearity, ruggedness and robustness. The linear regression analysis data for calibration plots showed good linear relationship in the concentration range 60-140 μg/mL for both glipizide and metformin hydrochloride.

  14. Application of a Validated Stability-Indicating LC Method for the Simultaneous Estimation of Tapentadol and Its Process-Related Impurities in Bulk and Its Dosage Form

    Directory of Open Access Journals (Sweden)

    Singaram Kathirvel

    2013-01-01

    Full Text Available Described is a first reported, simple, rapid, selective, and isocratic stability-indicating RP-LC method for the quantitative determination of tapentadol and its related substances in bulk samples and pharmaceutical dosage forms in the presence of its two process-related impurities. Chromatographic separation was achieved on the reversed phase, Enable column (C18 (5-μm, 250 × 4.6 mm, i.d. at ambient temperature using a mobile phase consisting of 0.02 M potassium dihydrogen orthophosphate (adjusted to pH 6 with 1 M KOH and acetonitrile (80 : 20, v/v. Flow rate was 1 mL/min and retention time was found to be 7.7 ± 0.05 min. Quantitation was achieved with UV detection at 215 nm based on peak area with linear calibration curves at concentration range 75–300 μg/mL. Forced degradation studies were performed, in accordance with ICH guidelines, using acidic, alkaline, oxidative, neutral, photolytic, and thermal conditions. The drug was found to be stable under all the conditions. The developed method was validated in terms of precision, robustness, recovery, and limits of detection and quantitation. Regression analysis shows an “r” value (correlation coefficient of greater than 0.999 for tapentadol and two potential impurities.

  15. Reconstructing the history of selection during homoploid hybrid speciation.

    Science.gov (United States)

    Karrenberg, Sophie; Lexer, Christian; Rieseberg, Loren H

    2007-06-01

    This study aims to identify selection pressures during the historical process of homoploid hybrid speciation in three Helianthus (sunflower) hybrid species. If selection against intrinsic genetic incompatibilities (fertility selection) or for important morphological/ecological traits (phenotypic selection) were important in hybrid speciation, we would expect this selection to have influenced the parentage of molecular markers or chromosomal segments in the hybrid species' genomes. To infer past selection, we compared the parentage of molecular markers in high-density maps of the three hybrid species with predicted marker parentage from an analysis of fertility selection in artificial hybrids and from the directions of quantitative trait loci effects with respect to the phenotypes of the hybrid species. Multiple logistic regression models were consistent with both fertility and phenotypic selection in all three species. To further investigate traits under selection, we used a permutation test to determine whether marker parentage predicted from groups of functionally related traits differed from neutral expectations. Our results suggest that trait groups associated with ecological divergence were under selection during hybrid speciation. This study presents a new method to test for selection and supports earlier claims that fertility selection and phenotypic selection on ecologically relevant traits have operated simultaneously during sunflower hybrid speciation.

  16. Speciation by selection: A framework for understanding ecology's role in speciation

    Institute of Scientific and Technical Information of China (English)

    R.Brian LANGERHANS; Rüdiger RIESCH

    2013-01-01

    Speciation research during the last several decades has confirmed that natural selection frequently drives the generation of new species.But how does this process generally unfold in nature? We argue that answering this question requires a clearer conceptual framework for understanding selection's role in speciation.We present a unified framework of speciation,providing mechanistic descriptions of fundamentally distinct routes to speciation,and how these may interact during lineage splitting.Two major categories are recognized:reproductive isolation resulting from (1) responses to selection,"speciation by selection,"or (2) non-selective processes,"speciation without selection." Speciation by selection can occur via three mechanisms:(1) similar selection,(2) divergent selection,and (3) reinforcement selection.Understanding ecology's role in speciation requires uncovering how these three mechanisms contribute to reproductive isolation,and their relative importance compared to non-selective processes,because all three mechanisms can occur side-by-side during speciation.To accomplish this,we highlight examination of groups of organisms inhabiting replicated environmental gradients.This scenario is common in nature,and a large literature illustrates that both parallel and non-parallel responses to similar environments are widespread,and each can result in speciation.This recognition reveals four general pathways of speciation by similar or divergent selection-parallel and nonparallel responses to similar and divergent selection.Altogether,we present a more precise framework for speciation research,draw attention to some under-recognized features of speciation,emphasize the multidimensionality of speciation,reveal limitations of some previous tests and descriptions of speciation mechanisms,and point to a number of directions for future investigation [Current Zoology 59(1):31-52,2013].

  17. 密集烤房不同装烟方式比较研究%Comparison of Tobacco Leaf Loading Methods in Bulk Curing Barn

    Institute of Scientific and Technical Information of China (English)

    孙曙光; 周童; 顾会战; 彭毅; 汪健; 王鹏; 陈利平

    2012-01-01

    [目的]探索密集烤房的最佳装烟方式.[方法]以密集烤房挂杆方式为对照,比较研究了托架式烟夹、框架散叶、散叶插签装烟方式的配套设备成本、装烟量、用工量、烤后烟叶经济性状、能耗成本等状况.[结果]托架式烟夹、框架散叶、散叶插签装烟方式节能省工效果明显,3种装烟方式装烟量最大可提高71.43%,初烤烟经济性状均有所提高,符合现代烟草农业集约化和可持续发展要求.[结论]研究可为密集烤房不同装烟方式的优化提供参考依据.%[Objective] To explore the best tobacco leaf loading method. [Method] With hang poles as control group, bracket type smoke clamp, framework loose leaf and loose leaf cutting sign loading tobacco patterns were tested in bulk curing barn about corollary equipment cost, pack smoke volume, the employment quantity, roast tobacco leaf after economic characters, energy consumption cost. [Result] The results showed that bracket type smoke clamp, framework loose leaf and loose leaf cutting sign were much better than hang poles in energy and worker saving. Because largest amount of the three tobacco leaf loading method can be increased by 71. 43 % and initial flue-cured tobacco economic characters are improved so they accord with the modern tobacco agriculture. [Conclusion] The study provides reference basis for optimization of different tobacco loading method.

  18. The Development and Validation of a Stability-Indicating UHPLC-DAD Method for Determination of Perindopril l-Arginine in Bulk Substance and Pharmaceutical Dosage Form.

    Science.gov (United States)

    Paczkowska, Magdalena; Zalewski, Przemysław; Garbacki, Piotr; Talaczyńska, Alicja; Krause, Anna; Cielecka-Piontek, Judyta

    2014-01-01

    A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril l-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile-0.1 % formic acid (20:80 v/v) at a flow rate of 1 mL min(-1). The injection volume was 5.0 µL and the wavelength of detection was controlled at 230 nm. The selectivity of the UHPLC-DAD method was confirmed by determining perindopril l-arginine in the presence of degradation products formed during acid-base hydrolysis and oxidation as well as degradation in the solid state, at an increased relative air humidity and in dry air. The method's linearity was investigated in the ranges 0.40-1.40 µg mL(-1) for isomer I and 0.40-2.40 µg mL(-1) for isomer II of perindopril l-arginine. The UHPLC-DAD method met the precision and accuracy criteria for the determination of the isomers of perindopril l-arginine. The limits of detection and quantitation were 0.1503 and 0.4555 µg mL(-1) for isomer I and 0.0356 and 0.1078 µg mL(-1) for isomer II, respectively.

  19. Speciation of Fe(II) and Fe(III) by the modified ferrozine method, FIA-spectrophotometry, and flame AAS after cloud-point extraction

    Energy Technology Data Exchange (ETDEWEB)

    Giokas, Dimosthenis L.; Paleologos, Evangelos K.; Karayannis, Miltiades I. [Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina (Greece)

    2002-07-01

    A method has been developed for the simultaneous determination of traces of Fe(III) and Fe(II) in water by on-line coupling of spectrophotometry with flame atomic absorption spectrometry (FAAS). The method involves cloud-point extraction (CPE) of both species with ammonium pyrrolidinecarbodithioate (APDC) under standard conditions, which facilitates the in situ complexation and extraction of both species. Differentiation of the oxidation states of iron is achieved by using mathematical equations to overcome the interference of Fe(III) in the spectrophotometric determination of Fe(II) when they are both present in the same solution. In this manner the time-consuming and labor-intensive steps of preoxidation of Fe(II) or reduction of Fe(III) are eliminated. By preconcentrating a 10-mL sample solution detection limits as low as 7 {mu}g L{sup -1}, were obtained after a single-step extraction procedure. The relative standard deviation (n=4, 30 {mu}g L{sup -1}) was 2.6 % and 1.8 % for spectrophotometry and FAAS, respectively. Recoveries in the range of 96-105 % were obtained by analysis of spiked real samples. The method was further verified by analyzing a certified reference material (IMEP-9); for this the recovery was 98.5 %. (orig.)

  20. DEVELOPMENT AND VALIDATION OF FIRST ORDER DERIVATIVE UV SPECTROPHOTOMETRIC METHOD FOR SIMULTANEOUS ESTIMATION OF PROPRANOLOL HYDROCHLORIDE AND FLUNARIZINE DIHYDROCHLORIDE IN BULK AND COMBINED DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Wagh Dipmala Dilip

    2013-06-01

    Full Text Available The first order derivative of UV spectrometry method for simultaneous determination of Propranolol hydrochloride (PRO and Flunarizine dihydrochloride (FLU in pure bulk drug and combined dosage form was found to be simple, accurate, fast, precise and reproducible. The first derivative values measured at 289nm for PRO and 253nm for FLU. The linearity for zero order derivative method was carried out by using the concentration range 4-28µg/ml for PRO and 3-7µg/ml for FLU. The coefficient correlation of PRO and FLU for zero order was found to be 0.9995 and 0.9991 respectively. At zero crossing point of PRO (289nm FLU showed a measurable derivative absorbance where as at the zero crossing point of FLU (253nm, PRO showed appreciable derivative absorbance value. The coefficient correlation of PRO and FLU for first order derivative was found to be 0.9991 and 0.9995 respectively. Precision study showed that % RSD was within the range of acceptable limits (<2. The % recovery for PRO and FLU was found to be in the range of 98-102% and 100-101% respectively. The percentage assay was found to be as 99.5 and 100.12% for PRO and FLU. The results of analysis have been validated as per ICH Q2 (R1 guidelines. This method has applied successfully for the determination of PRO and FLU in its combination with a high percentage of recovery good accuracy and precision.

  1. Investigation of low-temperature electrical conduction mechanisms in highly resistive GaN bulk layers extracted with simple parallel conduction extraction method

    Energy Technology Data Exchange (ETDEWEB)

    Yildiz, A. [Ahi Evran University, Department of Physics, Faculty of Science and Arts, Kirsehir (Turkey); Ankara University, Department of Engineering Physics, Faculty of Engineering, Besevler, Ankara (Turkey); Lisesivdin, S.B. [Bilkent University, Nanotechnology Research Center, Bilkent, Ankara (Turkey); Kasap, M.; Ozcelik, S. [Gazi University, Department of Physics, Faculty of Science and Arts, Teknikokullar, Ankara (Turkey); Ozbay, E. [Bilkent University, Nanotechnology Research Center, Bilkent, Ankara (Turkey); Bilkent University, Department of Physics, Bilkent, Ankara (Turkey); Bilkent University, Department of Electrical and Electronics Engineering, Bilkent, Ankara (Turkey); Balkan, N. [University of Essex, School of Computer Science and Electronic Engineering, Colchester (United Kingdom)

    2010-03-15

    The electrical conduction mechanisms in various highly resistive GaN layers of Al{sub x}Ga{sub 1-x}N/AlN/GaN/AlN heterostructures are investigated in a temperature range between T=40 K and 185 K. Temperature-dependent conductivities of the bulk GaN layers are extracted from Hall measurements with implementing simple parallel conduction extraction method (SPCEM). It is observed that the resistivity ({rho}) increases with decreasing carrier density in the insulating side of the metal-insulator transition for highly resistive GaN layers. Then the conduction mechanism of highly resistive GaN layers changes from an activated conduction to variable range hopping conduction (VRH). In the studied temperature range, ln ({rho}) is proportional to T{sup -1/4} for the insulating sample and proportional to T{sup -1/2} for the more highly insulating sample, indicating that the transport mechanism is due to VRH. (orig.)

  2. Arsenic speciation in edible mushrooms.

    Science.gov (United States)

    Nearing, Michelle M; Koch, Iris; Reimer, Kenneth J

    2014-12-16

    The fruiting bodies, or mushrooms, of terrestrial fungi have been found to contain a high proportion of the nontoxic arsenic compound arsenobetaine (AB), but data gaps include a limited phylogenetic diversity of the fungi for which arsenic speciation is available, a focus on mushrooms with higher total arsenic concentrations, and the unknown formation and role of AB in mushrooms. To address these, the mushrooms of 46 different fungus species (73 samples) over a diverse range of phylogenetic groups were collected from Canadian grocery stores and background and arsenic-contaminated areas. Total arsenic was determined using ICP-MS, and arsenic speciation was determined using HPLC-ICP-MS and complementary X-ray absorption spectroscopy (XAS). The major arsenic compounds in mushrooms were found to be similar among phylogenetic groups, and AB was found to be the major compound in the Lycoperdaceae and Agaricaceae families but generally absent in log-growing mushrooms, suggesting the microbial community may influence arsenic speciation in mushrooms. The high proportion of AB in mushrooms with puffball or gilled morphologies may suggest that AB acts as an osmolyte in certain mushrooms to help maintain fruiting body structure. The presence of an As(III)-sulfur compound, for the first time in mushrooms, was identified in the XAS analysis. Except for Agaricus sp. (with predominantly AB), inorganic arsenic predominated in most of the store-bought mushrooms (albeit with low total arsenic concentrations). Should inorganic arsenic predominate in these mushrooms from contaminated areas, the risk to consumers under these circumstances should be considered.

  3. Estimating the duration of speciation from phylogenies

    NARCIS (Netherlands)

    Etienne, Rampal S.; Morlon, Helene; Lambert, Amaury

    2014-01-01

    Speciation is not instantaneous but takes time. The protracted birth-death diversification model incorporates this fact and predicts the often observed slowdown of lineage accumulation toward the present. The mathematical complexity of the protracted speciation model has barred estimation of its par

  4. Adaptive speciation theory : A conceptual review

    NARCIS (Netherlands)

    Weissing, Franz J.; Edelaar, Pim; van Doorn, G. Sander

    2011-01-01

    Speciation-the origin of new species-is the source of the diversity of life. A theory of speciation is essential to link poorly understood macro-evolutionary processes, such as the origin of biodiversity and adaptive radiation, to well understood micro-evolutionary processes, such as allele frequenc

  5. Cd(II) Speciation in alginate gels

    NARCIS (Netherlands)

    Davis, T.A.; Kalis, E.J.J.; Pinheiro, J.P.; Town, R.M.; Leeuwen, van H.P.

    2008-01-01

    Polysaccharides, such as those occurring in cell walls and biofilms, play an important role in metal speciation in natural aqueous systems. This work describes the speciation of Cd(II) in alginate gels chosen as a model system for biogels. The gels are formed by bridging calcium ions at junction zon

  6. Speciation of heavy metals in River Rhine

    NARCIS (Netherlands)

    Vega, F.A.; Weng, L.

    2013-01-01

    Chemical speciation of Zn, Cu, Ni, Cd and Pb in River Rhine was studied by measuring free ion concentration and distribution in nanoparticles, and by comparing the measurement with speciation modeling. Concentrations of free metal ions were determined in situ using Donnan Membrane Technique (DMT). T

  7. Ion-pair chromatography coupled to inductively coupled plasma-mass spectrometry (IPC-ICP-MS) as a method for thiomolybdate speciation in natural waters.

    Science.gov (United States)

    Lohmayer, Regina; Reithmaier, Gloria Maria Susanne; Bura-Nakić, Elvira; Planer-Friedrich, Britta

    2015-03-17

    Molybdenum precipitates preferentially under reducing conditions; therefore, its occurrence in sediment records is used as an indicator of paleoredox conditions. Although thiomolybdates (MoO4-xSx(2-) with x = 1-4) supposedly are necessary intermediates in the process of molybdenum precipitation under anoxic conditions, there is no information about their abundance in natural environments, because of a lack of element-specific methods with sufficiently low detection limits. Here, we optimized ion-pair chromatographic separation for coupling to an inductively coupled plasma-mass spectrometry detector (IPC-ICP-MS). 2-Propanol (10%-25% gradient) replaced the previously used acetonitrile (25%-75%) as the solvent, to reduce the carbon load into the plasma. In synthetic solutions, formation of thiomolybdates was found to occur spontaneously in the presence of excess sulfide and the degree of thiolation was highest at pH 7. Excess hydroxyl led to a transformation of thiomolybdates to molybdate. Under acidic to neutral conditions, precipitation of molybdenum and hydrolysis of tetrathiomolybdate were observed. Flash-freezing was found to be suitable to stabilize tetrathiomolybdate, with 2 mM) negatively affected the detection of molybdate, which eluted mainly in the dead volume, but had no negative effect on higher thiolated molybdates. Detection limits were ∼10 nM. With the newly developed IPC-ICP-MS method, thiomolybdates were found to form spontaneously in euxinic marine waters after adding a molybdate spike and occur naturally in sulfidic geothermal waters.

  8. The Construction and Validation of All-Atom Bulk-Phase Models of Amorphous Polymers Using the TIGER2/TIGER3 Empirical Sampling Method.

    Science.gov (United States)

    Li, Xianfeng; Murthy, Sanjeeva; Latour, Robert A

    2011-07-12

    A new empirical sampling method termed "temperature intervals with global exchange of replicas and reduced radii" (TIGER3) is presented and demonstrated to efficiently equilibrate entangled long-chain molecular systems such as amorphous polymers. The TIGER3 algorithm is a replica exchange method in which simulations are run in parallel over a range of temperature levels at and above a designated baseline temperature. The replicas sampled at temperature levels above the baseline are run through a series of cycles with each cycle containing four stages - heating, sampling, quenching, and temperature level reassignment. The method allows chain segments to pass through one another at elevated temperature levels during the sampling stage by reducing the van der Waals radii of the atoms, thus eliminating chain entanglement problems. Atomic radii are then returned to their regular values and re-equilibrated at elevated temperature prior to quenching to the baseline temperature. Following quenching, replicas are compared using a Metropolis Monte Carlo exchange process for the construction of an approximate Boltzmann-weighted ensemble of states and then reassigned to the elevated temperature levels for additional sampling. Further system equilibration is performed by periodic implementation of the previously developed TIGER2 algorithm between cycles of TIGER3, which applies thermal cycling without radii reduction. When coupled with a coarse-grained modeling approach, the combined TIGER2/TIGER3 algorithm yields fast equilibration of bulk-phase models of amorphous polymer, even for polymers with complex, highly branched structures. The developed method was tested by modeling the polyethylene melt. The calculated properties of chain conformation and chain segment packing agreed well with published data. The method was also applied to generate equilibrated structural models of three increasingly complex amorphous polymer systems: poly(methyl methacrylate), poly

  9. Rapid parapatric speciation on holey adaptive landscapes

    CERN Document Server

    Gavrilets, S; Vose, M D; Gavrilets, Sergey; Li, Hai; Vose, Michael D.

    1998-01-01

    A classical view of speciation is that reproductive isolation arises as a by-product of genetic divergence. Here, individual-based simulations are used to evaluate whether the mechanisms implied by this view may result in rapid speciation if the only source of genetic divergence are mutation and random genetic drift. Distinctive features of the simulations are the consideration of the complete process of speciation (from initiation until completion), and of a large number of loci, which was only one order of magnitude smaller than that of bacteria. It is demonstrated that rapid speciation on the time scale of hundreds of generations is plausible without the need for extreme founder events, complete geographic isolation, the existence of distinct adaptive peaks or selection for local adaptation. The plausibility of speciation is enhanced by population subdivision. Simultaneous emergence of more than two new species from a subdivided population is highly probable. Numerical examples relevant to the theory of ce...

  10. Plant invasion and speciation along elevational gradients on the oceanic island La Palma, Canary Islands

    DEFF Research Database (Denmark)

    Steinbauer, Manuel; Irl, Severin David Howard; González-Mancebo, Juana Maria;

    2016-01-01

    Background: Ecosystems that provide environmental opportunities but are poor in species and functional richness generally support speciation as well as invasion processes. These processes are expected not to be equally effective along elevational gradients due to specific ecological, spatial...... and anthropogenic filters, thus controlling the dispersal and establishment of species. Here, we investigate speciation and invasion processes along elevational gradients. Methods: We assess the vascular plant species richness as well as the number and percentage of endemic species and non-native species...

  11. A novel validated RP-HPLC-DAD method for the simultaneous estimation of Metformin Hydrochloride and Canagliflozin in bulk and pharmaceutical tablet dosage form with forced degradation studies

    Directory of Open Access Journals (Sweden)

    Uttam Prasad Panigrahy

    2015-09-01

    Full Text Available A novel approach was used to develop and validate a rapid isocratic Reversed Phase-High Performance Liquid Chromatographic method for the simultaneous estimation of Metformin Hydrochloride and Canagliflozin in bulk and pharmaceutical tablet dosage form with forced degradation studies. The separation was performed by using Kromasil C18 column (250mm×4.6 mm, 5mm particle size, Waters Alliance e2695 HPLC system with 2998 PDA detector and mobile phase contained a mixture of 0.01M Ammonium acetate (pH adjusted to 3.5 with orthophosphoric acid and Acetonitrile (65:35, v/v. The flow rate was set to 1ml/min with responses measured at 254nm. The retention time of Metformin Hydrochloride and Canagliflozin was 2.440min and 3.713min respectively with resolution of 8.95.Linearity was established in the range of 50-300µg/ml for Metformin Hydrochloride and 5-30µg/ml for Canagliflozin with correlation coefficients (r2=0.999. The percentage recoveries were between (99.45%-100.65% and (99.95%-100.74% for Metformin Hydrochloride and Canagliflozin respectively. Validation parameters were evaluated according to the International Conference on Harmonization (ICH Q2 R1 guidelines. The forced degradation studies were performed by using HCl, NaOH, H2O2, thermal, UV radiation and water. Metformin Hydrochloride and Canagliflozin are more sensitive towards oxidative degradation condition. The developed method was successfully applied for the quantification and hyphenated instrumental analysis.

  12. Novel speciation method based on Diffusive Gradients in Thin Films for in situ measurement of uranium in the vicinity of the former uranium mining sites.

    Science.gov (United States)

    Drozdzak, Jagoda; Leermakers, Martine; Gao, Yue; Phrommavanh, Vannapha; Descostes, Michael

    2016-07-01

    The Diffusive Gradients in Thin Films (DGT) technique using PIWBA resin (The Dow Chemical Company) was developed and validated for the measurement of uranium (U) concentration in natural and uranium mining influenced waters. The U uptake on the PIWBA resin gel was 97.3 ± 0.4% (batch method; Vsol = 5 mL; [U] = 20 μg L(-1); 0.01 M NaNO3; pH = 7.0 ± 0.2). The optimal eluent was found to be HNO3conc/70 °C with an elution efficiency of 88.9 ± 1.4%. The laboratory DGT investigation demonstrated that the PIWBA resin gel exhibits a very good performance across a wide range of pH (3-9) and ionic strength (0.001-0.7 M NaNO3) at different time intervals. Neither effect of PO4(3-) (up to 1.72 × 10(-4) M), nor of HCO3(-) (up to 8.20 × 10(-3) M) on the quantitative measurement of uranium by DGT-PIWBA method were observed. Only at very high Ca(2+) (2.66 × 10(-4) M), and SO4(2-) (5.55 × 10(-4) M) concentration, the U uptake on DGT-PIWBA was appreciably lessened. In-situ DGT field evaluation was carried out in the vicinity of three former uranium mining sites in France (Loire-Atlantique and Herault departments), which employ different water treatment technologies and have different natural geochemical characteristics. There was a similar or inferior U uptake on DGT-Chelex(®)-100 in comparison with the U accumulation on a DGT-PIWBA sampler. Most likely, the performance of Chelex(®)-100 was negatively affected by a highly complex matrix of mining waters. The high concentration and identity of co-accumulating analytes, typical for the mining environment, did not have a substantial impact on the quantitative uptake of labile U species on DGT- PIWBA. The use of the polyphenol impregnated anion exchange resin leads to a significant advancement in the application and development of the DGT technique for determination of U in the vicinity of the former uranium mining sites.

  13. Potential ability of 3 T-class trapped field on MgB2 bulk surface synthesized by the infiltration-capsule method

    Science.gov (United States)

    Naito, Tomoyuki; Ogino, Arata; Fujishiro, Hiroyuki

    2016-11-01

    We successfully synthesized a dense (˜90%-filled) MgB2 bulk with no residual Mg via an infiltration process by overcoming the problems in this process such as the expansion of a B precursor disk under a liquid Mg infiltration and the residuals of unreacted Mg in the bulk using a specially designed capsule. As a result, we have achieved a record-high trapped field to date, {B}{{T}}, of 2.4 T at the center of the bulk surface at the lowest temperature of 15.9 K among the infiltration-processed MgB2 bulks. The trapped-fields simulated for a model with the experimental {J}{{c}}({μ }0H) characteristics well reproduced the experimental {B}{{T}}’s and gave a reliable estimated {B}{{T}} below 15.9 K. The extrapolation of the experimental and simulated {B}{{T}} curve reached 3 T at 4.2 K. The critical current densities, {J}{{c}}({μ }0H)’s, at 20 K were 1.8 × 105 A cm-2 under the self-field and 4.5 × 103 A cm-2 under the magnetic-field of {μ }0H = 3 T. The connectivity, K, of 16% of the present bulk was comparable with that of the ˜50%-filled MgB2 bulk. The high {B}{{T}} with low K and the microstructure of the present bulk suggested that the high- and low-{J}{{c}} regions coexisted because of the wide variation of the MgB2 grain-size.

  14. Validation of Two-Control-Volume Bulk Flow Method for Rotordynamic Characteristics of Hole-Pattern Seals%Bulk Flow方法分析孔型密封转子动力特性的有效性

    Institute of Scientific and Technical Information of China (English)

    晏鑫; 李军; 丰镇平

    2009-01-01

    基于Kleynhans和Childs的两控制容积等温BF(Bulk Flow)模型,通过增加能量方程和理想气体状态方程,建立了理想气体BF方法的数学模型,来预测和分析孔型密封转子在偏心状态下的静力学和动力学特性.由于转子在密封中心附近做微小涡动,故可通过采用摄动方法使得NS方程的求解过程得到较大的简化,再通过迭代求解简化后的零阶和一阶摄动方程组,就可以求出孔型密封的流场和动力特性系数.以此为依据发展了相关程序,计算出了不同工况条件下孔型密封的转子动力特性系数与激振频率的关系,通过与已有的实验数据和等温BF模型的计算结果进行对比,验证了理想气体BF模型及相关求解方法的有效性.结果表明:理想气体BF模型的预测结果与实验数据吻合良好,且优于等温BF模型的计算结果,证明了该理想气体BF模型的正确性和计算方法的可靠性.该方法可用于孔型密封动力特性的预测.

  15. Looking for a bulk point

    CERN Document Server

    Maldacena, Juan; Zhiboedov, Alexander

    2015-01-01

    We consider Lorentzian correlators of local operators. In perturbation theory, singularities occur when we can draw a position-space Landau diagram with null lines. In theories with gravity duals, we can also draw Landau diagrams in the bulk. We argue that certain singularities can arise only from bulk diagrams, not from boundary diagrams. As has been previously observed, these singularities are a clear diagnostic of bulk locality. We analyze some properties of these perturbative singularities and discuss their relation to the OPE and the dimensions of double-trace operators. In the exact nonperturbative theory, we expect no singularity at these locations. We prove this statement in 1+1 dimensions by CFT methods.

  16. Surveying selenium speciation from soil to cell - forms and transformations

    Energy Technology Data Exchange (ETDEWEB)

    Gammelgaard, Bente; Gabel-Jensen, Charlotte [University of Copenhagen, Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, Copenhagen (Denmark); Jackson, Matthew I. [Grand Forks Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Grand Forks, ND (United States)

    2011-02-15

    The aim of this review is to present and evaluate the present knowledge of which selenium species are available to the general population in the form of food and common supplements and how these species are metabolized in mammals. The overview of the selenium sources takes a horizontal approach, which encompasses identification of new metabolites in yeast and food of plant and animal origin, whereas the survey of the mammalian metabolism takes a horizontal as well as a vertical approach. The vertical approach encompasses studies on dynamic conversions of selenium compounds within cells, tissues or whole organisms. New and improved sample preparation, separation and detection methods are evaluated from an analytical chemical perspective to cover the progress in horizontal speciation, whereas the analytical methods for the vertical speciation and the interpretations of the results are evaluated from a biological angle as well. (orig.)

  17. Environmental harshness, latitude and incipient speciation.

    Science.gov (United States)

    Weir, Jason T

    2014-02-01

    Are rates of evolution and speciation fastest where diversity is greatest - the tropics? A commonly accepted theory links the latitudinal diversity gradient to a speciation pump model whereby the tropics produce species at a faster rate than extra-tropical regions. In this issue of Molecular Ecology, Botero et al. () test the speciation pump model using subspecies richness patterns for more than 9000 species of birds and mammals as a proxy for incipient speciation opportunity. Rather than using latitudinal centroids, the authors investigate the role of various environmental correlates of latitude as drivers of subspecies richness. Their key finding points to environmental harshness as a positive predictor of subspecies richness. The authors link high subspecies richness in environmental harsh areas to increased opportunities for geographic range fragmentation and/or faster rates of trait evolution as drivers of incipient speciation. Because environmental harshness generally increases with latitude, these results suggest that opportunity for incipient speciation is lowest where species richness is highest. The authors interpret this finding as incompatible with the view of the tropics as a cradle of diversity. Their results are consistent with a growing body of evidence that reproductive isolation and speciation occur fastest at high latitudes.

  18. Phylogenetic test of speciation by host shift in leaf cone moths (Caloptilia) feeding on maples (Acer).

    Science.gov (United States)

    Nakadai, Ryosuke; Kawakita, Atsushi

    2016-07-01

    The traditional explanation for the exceptional diversity of herbivorous insects emphasizes host shift as the major driver of speciation. However, phylogenetic studies have often demonstrated widespread host plant conservatism by insect herbivores, calling into question the prevalence of speciation by host shift to distantly related plants. A limitation of previous phylogenetic studies is that host plants were defined at the family or genus level; thus, it was unclear whether host shifts predominate at a finer taxonomic scale. The lack of a statistical approach to test the hypothesis of host-shift-driven speciation also hindered studies at the species level. Here, we analyze the radiation of leaf cone moths (Caloptilia) associated with maples (Acer) using a newly developed, phylogeny-based method that tests the role of host shift in speciation. This method has the advantage of not requiring complete taxon sampling from an entire radiation. Based on 254 host plant records for 14 Caloptilia species collected at 73 sites in Japan, we show that major dietary changes are more concentrated toward the root of the phylogeny, with host shift playing a minor role in recent speciation. We suggest that there may be other roles for host shift in promoting herbivorous insect diversification rather than facilitating speciation per se.

  19. Arsenic speciation in clinical samples: urine analysis using fast micro-liquid chromatography ICP-MS.

    Science.gov (United States)

    Morton, Jackie; Leese, Elizabeth

    2011-02-01

    Arsenic speciation is a subject that is developing all the time both from improvements in analytical techniques and from increases in toxicological understanding. Despite speciation methods being widely developed, arsenic speciation is not routinely offered as an analysis in clinical laboratory. The work in this paper describes a simple routine method for arsenic speciation that could be easily implemented in clinical laboratories. The method described, a new, fast analytical method for arsenic speciation, is reported using micro-liquid chromatography hyphenated to an inductively coupled plasma mass spectrometer (μLC-ICP-MS). The method uses a low-pressure delivery six-port valve with a 5 cm anion exchange column, which allows a fully resolved separation of five arsenic species (arsenobetaine [AB], arsenite [As(3+)], arsenate [As(5+)], mono-methylarsonic acid [MMA(5+)] and dimethylarsinic acid [DMA(5+)]) in urine in just 6 min. This fast analytical method offers an arsenic speciation method that is feasible for a laboratory that does not have the capability for a dedicated arsenic speciation LC-ICP-MS instrument. The micro-LC system is small, easy to install and is fully integrated with the ICP-MS software. The results reported here are from urine samples from 65 workers in a semiconductor work providing a sample for their routine biological monitoring to assess workplace exposure. Control samples from 20 unexposed people were also determined. Results show that the semiconductor workers exhibit very low levels of arsenic in their urine samples, similar to the levels in the controls, and thus are not significantly exposed to arsenic. Care must be taken when interpreting urinary arsenic species results because it is not always possible to differentiate between dietary and other external sources of exposure.

  20. Arsenic localization and speciation in the root-soil interface of the desert plant Prosopis juliflora-velutina.

    Science.gov (United States)

    Castillo-Michel, Hiram; Hernandez-Viezcas, Jose A; Servin, Alia; Peralia-Videa, Jose R; Gardea-Torresdey, Jorge L

    2012-06-01

    The bioavailability and mobility of arsenic (As) in soils depends on several factors such as pH, organic matter content, speciation, and the concentration of oxides and clay minerals, among others. Plants modify As bioavailability in the rhizosphere; thus, the biogeochemical processes of As in vegetated and non-vegetated soils are different. Changes in As speciation induced by the rhizosphere can be monitored using micro-focused synchrotron-based X-ray fluorescence (μXRF) combined with μX-ray absorption near-edge spectroscopy (μXANES). This research investigated As speciation in the rhizosphere of mesquite (Prosopis juliflora-velutina) plants grown in a sandy clay loam treated with As(III) and As(V) at 40 mg kg(-1). Rhizosphere soil and freeze-dried root tissues of one-month-old plants were analyzed by bulk XAS. Bulk XAS results showed that As(V) was the predominant species in the soil (rhizosphere and non-vegetated), whereas As(III) was dominant in the root tissues from both As(V) and As(III) treated plants. μXAS and μXRF studies of thin sections from resin embedded soil cores revealed the As(III)-S interactions in root tissues and a predominant As-Fe interaction in the soil. This research demonstrated that the combination of bulk XAS and μXAS techniques is a powerful analytical technique for the study of As speciation in soil and plant samples.

  1. Large area bulk superconductors

    Science.gov (United States)

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  2. Trace metal characterization and speciation in geothermal effluent by multiple scanning anodic stripping voltammetry and atomic absorption analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, B.R.

    1979-05-25

    Recent studies have shown geothermal power plants to have a significant environmental impact on the ground water of the area. The heavy metals arsenic and mercury are special problems, as both are concentrated by flora and fauna exposed to the effluent waters. Because the toxicity of these and other metallic pollutants present in geothermal effluent depends on the chemical form, or speciation, of the particular metal, any serious study of the environmental impact of a geothermal development should include studies of trace metal speciation, in addition to trace metal concentration. This proposal details a method for determining metal speciation in dilute waters. The method is based on ion-exchange and backed by atomic absorption spectrometry and multiple scanning anodic stripping voltammetry. Special laboratory studies will be performed on mercury, arsenic and selenium speciation in synthetic geothermal water. The method will be applied to three known geothermal areas in Washington and Oregon, with emphasis on the speciation of mercury, arsenic and selenium in these waters. The computer controlled electrochemical instrumentation was built and tested. Using this instrumentation, a new experimental procedure was developed to determine the chemical form (speciation) of metal ions in very dilute solutions (ng/ml). This method was tested on model systems including Pb, Cd, and As with C1/sup -/, CO/sub 3//sup 2 -/ and glycine ligands. Finally, the speciation of lead in a geothermal water was examined and the PbC1/sup +/ complex was observed and quantified.

  3. Simultaneous Forecast for Three Speciations of Heavy Metal Elements Using Fuzzy Cluster-Artificial Neural Network

    Institute of Scientific and Technical Information of China (English)

    ZHAO Tian-qi; MENG Fan-yu; WANG Hong-yan; GAO Yan

    2012-01-01

    Abstract The three speciations(water extract,adsorption and organic speciations) of Cu,Zn,Fe and Mn in geo-chemical samples were determined by fuzzy cluster-artificial neural network(FC-ANN) method coupled with atomic absorption spectrometry.A back-propagation artificial neural network with one input node and three export nodes was constructed,which could forecaste three speciations of heavy metals simultaneously.In the learning sample set,the three speciations of each element were allowed to change in a wide concentration range and the accuracy of the analysis was apparently increased via the learning sample set optimized with the help of the fuzzy cluster analysis.The average relative errors of the three speciations of Cu,Zn,Fe or Mn from 100 geo-chemical samples were less than 5%.The relative standard deviations of the three speciations of each of four heavy metals were 0.008%-4.43%.

  4. Development and validation of a general non-digestive method for the determination of palladium in bulk pharmaceutical chemicals and their synthetic intermediates by graphite furnace atomic absorption spectroscopy.

    Science.gov (United States)

    Wang, T; Walden, S; Egan, R

    1997-02-01

    A simple, selective, sensitive, accurate and relatively inexpensive method for the determination of palladium in bulk pharmaceutical chemicals (BPC) and their synthetic intermediates by graphite furnace atomic absorption spectroscopy has been developed and validated. Sample preparation by direct dissolution of sample in 70% nitric acid is simple and effective without adverse effects. The limit of detection and the limit of quantitation of the method were determined to be 0.7 ppm and 2 ppm respectively in BPC.

  5. Speciation of Pb in industrially polluted soils

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Ottosen, Lisbeth M.; Pedersen, Anne Juul

    2006-01-01

    This study was aimed at elucidating the importance of original Pb-speciation versus soil-characteristics to mobility and distribution of Pb in industrially polluted soils. Ten industrially polluted Danish surface soils were characterized and Pb speciation was evaluated through SEM-EDX studies......, examination of pH-dependent desorption, distribution in grain-size fractions and sequential extraction. Our results show that the first factors determining the speciation of Pb in soil are: (1) the stability of the original speciation and (2) the contamination level, while soil characteristics...... are of secondary importance. In nine of ten soils Pb was concentrated strongly in the soil fines (soils, particles with a highly concentrated Pb-content were observed during SEM-EDX. In eight of the soils, the particles contained various Pb-species with aluminum/iron, phosphate, sulfate...

  6. Speciation by Symbiosis: the Microbiome and Behavior

    OpenAIRE

    2016-01-01

    ABSTRACT Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasi...

  7. Tungsten Speciation in Firing Range Soils

    Science.gov (United States)

    2011-01-01

    The geochemical model MINTEQ was used to predict the stable thermo- dynamic phases in desorption isotherm experiments, and the equilibrium...tungstate adsorption in adsorption experiments. Visual MINTEQ v. 2.61 (Gustafsson 2009) is an equilibrium speciation model used to calculate the equilibrium...composition of dilute aqueous solutions from adsorp- tion−desorption experiments. MINTEQ is designed to describe aqueous speciation and mineral

  8. Recombination and the nature of bacterial speciation

    OpenAIRE

    2007-01-01

    Genetic surveys are uncovering the diversity of bacteria, and are causing the species concepts used to categorize these to be questioned. One difficulty in defining bacterial species arises from the high rates of recombination that results in the transfer of DNA between relatively distantly related bacteria. Barriers to this process, which could be used to define species naturally, are not apparent. Here, we have reviewed conceptual models of bacterial speciation and simulate speciation in si...

  9. Speciation and distribution of arsenic and localization of nutrients in rice grains

    Energy Technology Data Exchange (ETDEWEB)

    Lombi, E.; Scheckel, K.G.; Pallon, J.; Carey, A.M.; Zhu, Y.G.; Meharg, A.A. (EPA); (UCopenhagen); (Aberdeen); (Lund); (Chinese Aca. Sci.)

    2012-09-05

    Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques ({mu}-XANES, {mu}-X-ray fluorescence ({mu}-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.

  10. Refining the conditions for sympatric ecological speciation.

    Science.gov (United States)

    Débarre, F

    2012-12-01

    Can speciation occur in a single population when different types of resources are available, in the absence of any geographical isolation, or any spatial or temporal variation in selection? The controversial topics of sympatric speciation and ecological speciation have already stimulated many theoretical studies, most of them agreeing on the fact that mechanisms generating disruptive selection, some level of assortment, and enough heterogeneity in the available resources, are critical for sympatric speciation to occur. Few studies, however, have combined the three factors and investigated their interactions. In this article, I analytically derive conditions for sympatric speciation in a general model where the distribution of resources can be uni- or bimodal, and where a parameter controls the range of resources that an individual can exploit. This approach bridges the gap between models of a unimodal continuum of resources and Levene-type models with discrete resources. I then test these conditions against simulation results from a recently published article (Thibert-Plante & Hendry, 2011, J. Evol. Biol. 24: 2186-2196) and confirm that sympatric ecological speciation is favoured when (i) selection is disruptive (i.e. individuals with an intermediate trait are at a local fitness minimum), (ii) resources are differentiated enough and (iii) mating is assortative. I also discuss the role of mating preference functions and the need (or lack thereof) for bimodality in resource distributions for diversification.

  11. Speciation, in the nuclear fuel cycle by spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Colette, S.; Plancque, G.; Allain, F.; Lamouroux, C.; Steiner, V.; Amekraz, B.; Moulin, C. [CEA/Saclay, Dept, des Procedes d' Enrichissement (DPE), 91 - Gif-sur-Yvette (France)

    2000-07-01

    New analytical techniques allowing to perform speciation in the framework of the nuclear fuel cycle are more and more needed. They have to be selective (since matrix encountered are very complex), sensitive (in order to work at representative concentration and below solubility limit), as well as non intrusive (in order to keep the image of the real solution). Among them, laser-based analytical techniques present these advantages together with the possibility to perform remote measurements via fiber optics. Hence, Time-Resolved Laser-Induced Fluorescence (TRLIF) has been used for actinides/lanthanides interaction and speciation studies in inorganic and organic matrices from the reprocessing to waste storage. Moreover, new ion detection methods such as Electro-Spray - Mass Spectrometry (ES-MS) seems promising for speciation studies. Hence, it is the first time that it is possible to directly couple a liquid at atmospheric pressure to a mass detection working at reduced pressure with a soft mode of ionisation that should allow to give informations on chemical species present. Principle, advantages and limitations as well as results obtained with the use of TRLIF and ES-MS on different systems of interest including actinides, lanthanides, fission products in interaction with simple organic molecules to very complex structure will be presented and discussed. (authors)

  12. Selenium speciation in flue desulfurization residues.

    Science.gov (United States)

    Zhong, Liping; Cao, Yan; Li, Wenying; Xie, Kechang; Pan, Wei-Ping

    2011-01-01

    Flue gas from coal combustion contains significant amounts of volatile selenium (Se). The capture of Se in the flue gas desulfurization (FGD) scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the environmental impact of its disposal. A simple method has been developed for selective inorganic Se(IV), Se(VI) and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry (AFS). It has been determined that Se(IV), Se(VI) and organic Se can be accurately determined with detection limits (DL) of 0.05, 0.06 and 0.06 microg/L, respectively. The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists in a reduced state as selenite (Se(IV)). The toxicity of Se(IV) is the strongest of all Se species. Flue gas desulfurization residues pose a serious environmental risk.

  13. Selenium speciation in flue desulfurization residues

    Institute of Scientific and Technical Information of China (English)

    Liping Zhong; Yan Cao; Wenying Li; Kechang Xie; Wei-Ping Pan

    2011-01-01

    Flue gas from coal combustion contains significant amounts of volatile selenium (Se).The capture of Se in the flue gas desulfurization (FGD) scrubber unit has resulted in a generation of metal-laden residues.It is important to determine Se speciation to understand the environmental impact of its disposal.A simple method has been developed for selective inorganic Se(Ⅳ), Se(Ⅵ) and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry (AFS).It has been determined that Se(Ⅳ), Se(Ⅵ) and organic Se can be accurately determined with detection limits (DL) of 0.05, 0.06 and 0.06 μg/L, respectively.The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples.Analysis indicates that the concentration of Se is nigh in FGD liquid residues and primarily exists in a reduced state as selenite (Se(Ⅳ)).The toxicity of Se(Ⅳ) is the strongest of all Se species.Flue gas desulfurization residues pose a serious environmental risk.

  14. On speciation of VOC localization

    Science.gov (United States)

    Chen, S.; Chang, J.; Wang, J.

    2011-12-01

    Most of the gas-phase chemical mechanisms successfully used in gas-phase atmospheric chemical processes, such as CBM-Z, RADM2 or SAPRC-07, treat hundreds of VOC as lumped organic species by their chemical characteristics. Most of the model results are compared with total VOC observations, and it is not appropriate to compare lumped VOC simulations to observations even if there are separate VOC observations like Photochemical Assessment Monitoring Stations (PAMS). While the PAMS Air Quality Model (PAMS-AQM) is developed, separate organic species observed by PAMS without a doubt can be directly compared with model simulations. From the past case study (Chen et al., 2010), it shows a major and very significant finding in that detailed emissions of VOC in the existing emissions database are often in error in Taiwan or other countries due to the fact that the annual VOC emissions are classified into hundreds of species-specific emissions by using the speciation factors following the protocol of the U.S. EPA (AP-42). Based on all PAMS observations from 2006-2007, four base cases with well comparable meteorological simulations were selected for the unified correction for all sources in Taiwan. After the PAMS species emissions are modified, the diurnal patterns and simulation-observation correlation for most of the PAMS species are improved, and the concentration levels are more comparable with those of observations. More expanded case studies also revealed necessary corrections for the PAMS species emissions. Sensitivity analyses for lumped organic species with modified PAMS species emissions are also conducted. After modified PAMS emissions are added into lumped VOC emissions, there is an increase of only 10% of totally VOC emissions. While the sources of the lumped VOC emissions are changed, ozone formation shows no significant change with modified lumped VOC emissions. This helps to support the argument that for ozone simulation, the lumped VOC processes balance out

  15. Speciation rates decline through time in individual-based models of speciation and extinction.

    Science.gov (United States)

    Wang, Shaopeng; Chen, Anping; Fang, Jingyun; Pacala, Stephen W

    2013-09-01

    A well-documented pattern in the fossil record is a long-term decline in the origination rate of new taxa after diversity rebounds from a mass extinction. The mechanisms for this pattern remain elusive. In this article, we investigate the macroevolutionary predictions of an individual-based birth-death model (BDI model) where speciation and extinction rates emerge from population dynamics. We start with the simplest neutral model in which every individual has the same per capita rates of birth, death, and speciation. Although the prediction of the simplest neutral model agrees qualitatively with the fossil pattern, the predicted decline in per-species speciation rates is too fast to explain the long-term trend in fossil data. We thus consider models with variation among species in per capita rates of speciation and a suite of alternative assumptions about the heritability of speciation rate. The results show that interspecific variation in per capita speciation rate can induce differences among species in their ability to resist extinction because a low speciation rate confers a small but important demographic advantage. As a consequence, the model predicts an appropriately slow temporal decline in speciation rates, which provides a mechanistic explanation for the fossil pattern.

  16. Ecological speciation in marine v. freshwater fishes.

    Science.gov (United States)

    Puebla, O

    2009-10-01

    Absolute barriers to dispersal are not common in marine systems, and the prevalence of planktonic larvae in marine taxa provides potential for gene flow across large geographic distances. These observations raise the fundamental question in marine evolutionary biology as to whether geographic and oceanographic barriers alone can account for the high levels of species diversity observed in marine environments such as coral reefs, or whether marine speciation also operates in the presence of gene flow between diverging populations. In this respect, the ecological hypothesis of speciation, in which reproductive isolation results from divergent or disruptive natural selection, is of particular interest because it may operate in the presence of gene flow. Although important insights into the process of ecological speciation in aquatic environments have been provided by the study of freshwater fishes, comparatively little is known about the possibility of ecological speciation in marine teleosts. In this study, the evidence consistent with different aspects of the ecological hypothesis of speciation is evaluated in marine fishes. Molecular approaches have played a critical role in the development of speciation hypotheses in marine fishes, with a role of ecology suggested by the occurrence of sister clades separated by ecological factors, rapid cladogenesis or the persistence of genetically and ecologically differentiated species in the presence of gene flow. Yet, ecological speciation research in marine fishes is still largely at an exploratory stage. Cases where the major ingredients of ecological speciation, namely a source of natural divergent or disruptive selection, a mechanism of reproductive isolation and a link between the two have been explicitly documented are few. Even in these cases, specific predictions of the ecological hypothesis of speciation remain largely untested. Recent developments in the study of freshwater fishes illustrate the potential for

  17. Production, Properties and Applications of Bulk Amorphous Alloys

    Institute of Scientific and Technical Information of China (English)

    Tao Zhang; Akihisa Inoue

    2000-01-01

    A review is given of recent work concerned with the production method, the characteristic properties(1) Bulk amorphous system; (2) Mechanical and magnetic properties of bulkamorphous alloys; (3)application of bulk amorphous alloys.

  18. Speciation by Symbiosis: the Microbiome and Behavior

    Directory of Open Access Journals (Sweden)

    J. Dylan Shropshire

    2016-05-01

    Full Text Available Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasizing the patterns seen in these analyses and highlighting areas worthy of additional exploration. We conclude that the role of microbial symbionts in behavior and speciation is gaining exciting traction and that the holobiont and hologenome concepts afford an evolving intellectual framework to promote research and intellectual exchange between disciplines such as behavior, microbiology, genetics, symbiosis, and speciation. Given the increasing centrality of microbiology in macroscopic life, microbial symbiosis is arguably the most neglected aspect of animal and plant speciation, and studying it should yield a better understanding of the origin of species.

  19. Patterns of species ranges, speciation, and extinction.

    Science.gov (United States)

    Birand, Aysegul; Vose, Aaron; Gavrilets, Sergey

    2012-01-01

    The exact nature of the relationship among species range sizes, speciation, and extinction events is not well understood. The factors that promote larger ranges, such as broad niche widths and high dispersal abilities, could increase the likelihood of encountering new habitats but also prevent local adaptation due to high gene flow. Similarly, low dispersal abilities or narrower niche widths could cause populations to be isolated, but such populations may lack advantageous mutations due to low population sizes. Here we present a large-scale, spatially explicit, individual-based model addressing the relationships between species ranges, speciation, and extinction. We followed the evolutionary dynamics of hundreds of thousands of diploid individuals for 200,000 generations. Individuals adapted to multiple resources and formed ecological species in a multidimensional trait space. These species varied in niche widths, and we observed the coexistence of generalists and specialists on a few resources. Our model shows that species ranges correlate with dispersal abilities but do not change with the strength of fitness trade-offs; however, high dispersal abilities and low resource utilization costs, which favored broad niche widths, have a strong negative effect on speciation rates. An unexpected result of our model is the strong effect of underlying resource distributions on speciation: in highly fragmented landscapes, speciation rates are reduced.

  20. Speciation by Symbiosis: the Microbiome and Behavior.

    Science.gov (United States)

    Shropshire, J Dylan; Bordenstein, Seth R

    2016-03-31

    Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasizing the patterns seen in these analyses and highlighting areas worthy of additional exploration. We conclude that the role of microbial symbionts in behavior and speciation is gaining exciting traction and that the holobiont and hologenome concepts afford an evolving intellectual framework to promote research and intellectual exchange between disciplines such as behavior, microbiology, genetics, symbiosis, and speciation. Given the increasing centrality of microbiology in macroscopic life, microbial symbiosis is arguably the most neglected aspect of animal and plant speciation, and studying it should yield a better understanding of the origin of species.

  1. Speciation without Pre-Defined Fitness Functions.

    Science.gov (United States)

    Gras, Robin; Golestani, Abbas; Hendry, Andrew P; Cristescu, Melania E

    2015-01-01

    The forces promoting and constraining speciation are often studied in theoretical models because the process is hard to observe, replicate, and manipulate in real organisms. Most models analyzed to date include pre-defined functions influencing fitness, leaving open the question of how speciation might proceed without these built-in determinants. To consider the process of speciation without pre-defined functions, we employ the individual-based ecosystem simulation platform EcoSim. The environment is initially uniform across space, and an evolving behavioural model then determines how prey consume resources and how predators consume prey. Simulations including natural selection (i.e., an evolving behavioural model that influences survival and reproduction) frequently led to strong and distinct phenotypic/genotypic clusters between which hybridization was low. This speciation was the result of divergence between spatially-localized clusters in the behavioural model, an emergent property of evolving ecological interactions. By contrast, simulations without natural selection (i.e., behavioural model turned off) but with spatial isolation (i.e., limited dispersal) produced weaker and overlapping clusters. Simulations without natural selection or spatial isolation (i.e., behaviour model turned off and high dispersal) did not generate clusters. These results confirm the role of natural selection in speciation by showing its importance even in the absence of pre-defined fitness functions.

  2. How might epigenetics contribute to ecological speciation?

    Directory of Open Access Journals (Sweden)

    Gilbert SMITH, Michael G. RITCHIE

    2013-10-01

    Full Text Available Speciation research has seen a renewed interest in ecological speciation, which emphasises divergent ecological selection leading to the evolution of reproductive isolation. Selection from divergent ecologies means that phenotypic plasticity can play an important role in ecological speciation. Phenotypic plasticity involves the induction of phenotypes over the lifetime of an organism and emerging evidence suggests that epigenetic marks such as cytosine and protein (histone modifications might regulate such environmental induction. Epigenetic marks play a wide role in a variety of processes including development, sex differentiation and allocation, sexual conflict, regulation of transposable elements and phenotypic plasticity. Here we describe recent studies that investigate epigenetic mechanisms in a variety of contexts. There is mounting evidence for environmentally induced epigenetic variation and for the stable inheritance of epigenetic marks between generations. Thus, epigenetically-based phenotypic plasticity may play a role in adaptation and ecological speciation. However, there is less evidence for the inheritance of induced epigenetic variation across multiple generations in animals. Currently few studies of ecological speciation incorporate the potential for the involvement of epigenetically-based induction of phenotypes, and we argue that this is an important omission [Current Zoology 59 (5: 686-696, 2013 ].

  3. Bulk chemicals from biomass

    NARCIS (Netherlands)

    Haveren, van J.; Scott, E.L.; Sanders, J.P.M.

    2008-01-01

    Given the current robust forces driving sustainable production, and available biomass conversion technologies, biomass-based routes are expected to make a significant impact on the production of bulk chemicals within 10 years, and a huge impact within 20-30 years. In the Port of Rotterdam there is a

  4. A phylogenetic test of sympatric speciation in the Hydrobatinae (Aves: Procellariiformes).

    Science.gov (United States)

    Wallace, S J; Morris-Pocock, J A; González-Solís, J; Quillfeldt, P; Friesen, V L

    2017-02-01

    Phylogenetic relationships among species can provide insight into how new species arise. For example, careful consideration of both the phylogenetic and geographic distributions of species in a group can reveal the geographic models of speciation within the group. One such model, sympatric speciation, may be more common than previously thought. The Hydrobatinae (Aves: Procellariformes) is a diverse subfamily of Northern Hemisphere storm-petrels for which the taxonomy is unclear. Previous studies showed that Hydrobates (formally Oceanodroma) castro breeding in the Azores during the cool season is sister species to H. monteiroi, a hot season breeder at the same locations, which suggests sympatric speciation by allochrony. To test whether other species within the subfamily arose via sympatric speciation by allochrony, we sequenced the cytochrome b gene and five nuclear introns to estimate a phylogenetic tree using multispecies coalescent methods, and to test whether species breeding in the same geographic area are monophyletic. We found that speciation within the Hydrobatinae appears to have followed several geographic modes of divergence. Sympatric seasonal species in Japan likely did not arise through sympatric speciation, but allochrony may have played a role in the divergence of H. matsudairae, a cool season breeder, and H. monorhis, a hot season breeder. No other potential cases of sympatric speciation were discovered within the subfamily. Despite breeding in the same geographic area, hydrobatine storm-petrels breeding in Baja California (H. microsoma and H. melania) are each sister to a species breeding off the coast of Peru (H. tethys and H. markhami, respectively). In fact, antitropical sister species appear to have diverged at multiple times, suggesting allochronic divergence might be common. In addition, allopatry has likely played a role in divergence of H. furcata, a north Pacific breeder, and H. pelagius, a north Atlantic breeder. This study demonstrates

  5. Copper speciation in variably toxic sediments at the Ely Copper Mine, Vermont, United States

    Science.gov (United States)

    Kimball, Bryn E.; Foster, Andrea L.; Seal, Robert; Piatak, Nadine; Webb, Samuel M.; Hammarstrom, Jane M.

    2016-01-01

    At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160–1200 times) and sediments (15–79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80–95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu.

  6. Copper Speciation in Variably Toxic Sediments at the Ely Copper Mine, Vermont, United States.

    Science.gov (United States)

    Kimball, Bryn E; Foster, Andrea L; Seal, Robert R; Piatak, Nadine M; Webb, Samuel M; Hammarstrom, Jane M

    2016-02-01

    At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160-1200 times) and sediments (15-79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80-95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu.

  7. Speciation of arsenic, selenium, and chromium in wildfire impacted soils and ashes

    Science.gov (United States)

    Wolf, Ruth E.; Hoefen, Todd M.; Hageman, Philip L.; Morman, Suzette A.; Plumlee, Geoffrey S.

    2010-01-01

    In 2007-09, California experienced several large wildfires that damaged large areas of forest and destroyed many homes and buildings. The U.S. Geological Survey collected samples from the Harris, Witch, Grass Valley, Ammo, Santiago, Canyon, Jesusita, and Station fires for testing to identify any possible characteristics of the ashes and soils from burned areas that may be of concern for their impact on water quality, human health, and endangered species. The samples were subjected to analysis for bulk chemical composition for 44 elements by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion and de-ionized water leach tests for pH, alkalinity, conductivity, and anions. Water leach tests generated solutions ranging from pH 10-12, suggesting that ashes can generate caustic alkalinity in contact with rainwater or body fluids (for example, sweat and fluids in the respiratory tract). Samples from burned residential areas in the 2007 fires had elevated levels for several metals, including: As, Pb, Sb, Cu, Zn, and Cr. In some cases, the levels found were above the U.S. Environmental Protection Agency (USEPA) preliminary remediation goals (PRG) for soils. Speciation analyses were conducted on de-ionized water and simulated lung fluid leachates for As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI). All species were determined in the same analytical run using an ion-pairing HPLC-ICP-MS method. For leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent, Cr(VI), form. Higher total and hexavalent chromium levels were observed for samples collected from burned residential areas. Arsenic was also generally present in the more oxidized, As(V), form. Selenium (IV) and (VI) were present, but typically at levels below 2 ppb for most samples. Stability studies of leachate solutions under different storage conditions were performed and the suitability of different sample preservation methods for speciation

  8. Cobalt toxicity in anaerobic granular sludge: influence of chemical speciation

    NARCIS (Netherlands)

    Bartacek, J.; Fermoso, F.G.; Baldo-Urrutia, A.M.; Hullebusch, van E.D.; Lens, P.N.L.

    2008-01-01

    The influence of cobalt speciation on the toxicity of cobalt to methylotrophic methanogenesis in anaerobic granular sludge was investigated. The cobalt speciation was studied with three different media that contained varying concentrations of complexing ligands [carbonates, phosphates and ethylenedi

  9. Trace metal speciation in natural waters: Computational vs. analytical

    Science.gov (United States)

    Kirk, Nordstrom D.

    1996-01-01

    Improvements in the field sampling, preservation, and determination of trace metals in natural waters have made many analyses more reliable and less affected by contamination. The speciation of trace metals, however, remains controversial. Chemical model speciation calculations do not necessarily agree with voltammetric, ion exchange, potentiometric, or other analytical speciation techniques. When metal-organic complexes are important, model calculations are not usually helpful and on-site analytical separations are essential. Many analytical speciation techniques have serious interferences and only work well for a limited subset of water types and compositions. A combined approach to the evaluation of speciation could greatly reduce these uncertainties. The approach proposed would be to (1) compare and contrast different analytical techniques with each other and with computed speciation, (2) compare computed trace metal speciation with reliable measurements of solubility, potentiometry, and mean activity coefficients, and (3) compare different model calculations with each other for the same set of water analyses, especially where supplementary data on speciation already exist. A comparison and critique of analytical with chemical model speciation for a range of water samples would delineate the useful range and limitations of these different approaches to speciation. Both model calculations and analytical determinations have useful and different constraints on the range of possible speciation such that they can provide much better insight into speciation when used together. Major discrepancies in the thermodynamic databases of speciation models can be evaluated with the aid of analytical speciation, and when the thermodynamic models are highly consistent and reliable, the sources of error in the analytical speciation can be evaluated. Major thermodynamic discrepancies also can be evaluated by simulating solubility and activity coefficient data and testing various

  10. Monte Carlo simulations of parapatric speciation

    Science.gov (United States)

    Schwämmle, V.; Sousa, A. O.; de Oliveira, S. M.

    2006-06-01

    Parapatric speciation is studied using an individual-based model with sexual reproduction. We combine the theory of mutation accumulation for biological ageing with an environmental selection pressure that varies according to the individuals geographical positions and phenotypic traits. Fluctuations and genetic diversity of large populations are crucial ingredients to model the features of evolutionary branching and are intrinsic properties of the model. Its implementation on a spatial lattice gives interesting insights into the population dynamics of speciation on a geographical landscape and the disruptive selection that leads to the divergence of phenotypes. Our results suggest that assortative mating is not an obligatory ingredient to obtain speciation in large populations at low gene flow.

  11. [XANES study of lead speciation in duckweed].

    Science.gov (United States)

    Chu, Bin-Bin; Luo, Li-Qiang; Xu, Tao; Yuan, Jing; Sun, Jian-Ling; Zeng, Yuan; Ma, Yan-Hong; Yi, Shan

    2012-07-01

    Qixiashan lead-zinc mine of Nanjing was one of the largest lead zinc deposits in East China Its exploitation has been over 50 years, and the environmental pollution has also been increasing. The lead concentration in the local environment was high, but lead migration and toxic mechanism has not been clear. Therefore, biogeochemistry research of the lead zinc mine was carried out. Using ICP-MS and Pb-L III edge XANES, lead concentration and speciation were analyzed respectively, and duckweed which can tolerate and enriched heavy metals was found in the pollution area. The results showed that the lead concentration of duckweed was 39.4 mg x kg(-1). XANES analysis and linear combination fit indicated that lead stearate and lead sulfide accounted for 65% and 36.9% respectively in the lead speciation of duckweed, suggesting that the main lead speciation of duckweed was sulfur-containing lead-organic acid.

  12. Melting of SmBa2Cu3O7-y-seeds during preparation of YBCO Bulk Superconductors by Infiltration Growth Method

    Science.gov (United States)

    Vojtkova, L.; Diko, P.; Volochová, D.

    2016-03-01

    The conditions for single-grain growth of YBCO bulk superconductors by top seeded infiltration growth were tested. It is shown that the interaction of melt formed from BaCuO2 + CuO + Y2O3 precursor with the Sm123 seed causes dissolution of the seed at maximum melting temperature 1045 °C. Experiments with low weight Y211 pellet confirmed that the low concentration of Y in the infiltration melt is responsible for this effect. The most effective way suppressing the seed dissolution was shown to be the insertion of Y123 + Y211 buffer layer between the seed and the Y211 pellet. This buffer layer possesses the melt which is saturated with yttrium what prevents dissolution of the seed.

  13. SPECIATE Version 4.4 Database Development Documentation

    Science.gov (United States)

    SPECIATE is the U.S. Environmental Protection Agency’s (EPA) repository of volatile organic gas and particulate matter (PM) speciation profiles of air pollution sources. Some of the many uses of these source profiles include: (1) creating speciated emissions inventories for regi...

  14. Speciation and domestication in Suiformes: a genomic perspective

    NARCIS (Netherlands)

    Frantz, L.A.F.

    2015-01-01

    Abstract Frantz, L.A.F. (2015). Speciation and Domestication in Suiformes: a genomic perspective. PhD thesis, Wageningen University, the Netherlands The diversity of life on earth owes its existence to the process of speciation. The concept of speciation is primordial for evolutiona

  15. Phenotypic plasticity's impacts on diversification and speciation.

    Science.gov (United States)

    Pfennig, David W; Wund, Matthew A; Snell-Rood, Emilie C; Cruickshank, Tami; Schlichting, Carl D; Moczek, Armin P

    2010-08-01

    Phenotypic plasticity (the ability of a single genotype to produce multiple phenotypes in response to variation in the environment) is commonplace. Yet its evolutionary significance remains controversial, especially in regard to whether and how it impacts diversification and speciation. Here, we review recent theory on how plasticity promotes: (i) the origin of novel phenotypes, (ii) divergence among populations and species, (iii) the formation of new species and (iv) adaptive radiation. We also discuss the latest empirical support for each of these evolutionary pathways to diversification and identify potentially profitable areas for future research. Generally, phenotypic plasticity can play a largely underappreciated role in driving diversification and speciation.

  16. Liquid phase microextraction for the analysis of trace elements and their speciation

    Science.gov (United States)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated.

  17. Influence of magnetic fields on hysteretic ac losses in bulk MgB{sub 2} superconductor investigated by using Hall probe ac susceptibility method

    Energy Technology Data Exchange (ETDEWEB)

    Varilci, A [Faculty of Arts and Sciences, Department of Physics, Abant Izzet Baysal University, 14280 Bolu (Turkey)

    2007-04-15

    We report the results of an investigation of the influence of magnetic fields on hysteretic ac losses in bulk MgB{sub 2} superconductor by using Hall probe ac susceptibility. The external magnetic field in this study had an ac part with frequency 10 Hz and magnitude in the range 240-1200 A m{sup -1} and no dc part. We have measured the imaginary part of the magnetic susceptibility and analysed data by using Bean's critical state model of cylindrical geometry for four different temperature values 39.55, 39.51, 39.47 and 39.41 K. The result of this analysis indicates that Bean's model is adequate to explain the experimental findings. Calculated hysteretic ac loss versus applied magnetic field curve is given by using the critical state model. We have also measured the magnetization versus applied magnetic field and determined the first critical magnetic field of a MgB{sub 2} sample as 500 A m{sup -1} at 35 K.

  18. Factors Controlling Redox Speciation of Plutonium and Neptunium in Extraction Separation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Paulenova, Alena [Principal Investigator; Vandegrift, III, George F. [Collaborator

    2013-09-24

    The objective of the project was to examine the factors controlling redox speciation of plutonium and neptunium in UREX+ extraction in terms of redox potentials, redox mechanism, kinetics and thermodynamics. Researchers employed redox-speciation extractions schemes in parallel to the spectroscopic experiments. The resulting distribution of redox species w studied uring spectroscopic, electrochemical, and spectro-electrochemical methods. This work reulted in collection of data on redox stability and distribution of redox couples in the nitric acid/nitrate electrolyte and the development of redox buffers to stabilize the desired oxidation state of separated radionuclides. The effects of temperature and concentrations on the redox behavior of neptunium were evaluated.

  19. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    DEFF Research Database (Denmark)

    Cheng, Shaodong; Yang, Guang; Zhao, Yanqi;

    2015-01-01

    developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which...... fraction in glasses. In addition, the boron speciation of a CeO2 doped potassium borosilicate glass has been analyzed by using the time-resolved EELS spectra. The results clearly demonstrate that the BO4 to BO3 transformation induced by the electron beamirradiation can be efficiently suppressed by doping...

  20. Electrochemical metal speciation in colloidal dispersions.

    NARCIS (Netherlands)

    Wonders, J.H.A.M.

    1995-01-01

    The term "heavy metals" is connected with toxicity. They form strong complexes with enzymes, other proteins and DNA in living organisms, which causes dysfunctioning and hence poisoning. In combination with the uptake mechanism of the organism, speciation of heavy metal determines the bio-availabilit

  1. Speciation through the learning of habitat features.

    Science.gov (United States)

    Beltman, J B; Haccou, P

    2005-05-01

    Learning of environmental features can influence both mating behaviour and the location where young are produced. This may lead to speciation in three steps: (i) colonization of a new habitat, (ii) genetic divergence of the two groups by adaptation to the habitats, and (iii) a decrease of genetic mixing between the lineages (similar to reinforcement). In a previous paper we showed that steps (i) and (ii) occur readily for a wide range of fixed mating and habitat preferences. Here, we study whether this can ultimately lead to speciation through selective changes in these preferences. We show that this indeed occurs, and, furthermore, it is very general: for a large class of models there is selection toward producing young more frequently in the natal habitat. Once habitat preference is strong, there is selection toward stronger assortative mating. Even when steps (i) and (ii) initially fail, genetic divergence may succeed at a later evolutionary stage, after which a decrease of genetic mixing completes speciation. Our results show that speciation by the learning of habitat features is an extremely effective mechanism.

  2. Biosensor for metal analysis and speciation

    Science.gov (United States)

    Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

    2007-01-30

    A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

  3. Characterization of Technetium Speciation in Cast Stone

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Jung, Hun Bok; Wang, Guohui; Westsik, Joseph H.; Peterson, Reid A.

    2013-11-11

    This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Production and Long-Term Performance of Low Temperature Waste Forms” to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability from Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.

  4. EFFECT OF SCR CATALYST ON MERCURY SPECIATION

    Science.gov (United States)

    A pilot-scale research study was conducted to investigate the effect of selective catalytic reduction (SCR) on elemental mercury speciation in bituminous and subbituminous coal combustion flue gases. Three different Illinois bituminous coals and one Powder River Basin (PRB) coal...

  5. Behavioural reproductive isolation and speciation in Drosophila

    Indian Academy of Sciences (India)

    Punita Nanda; Bashisth Narayan Singh

    2012-06-01

    The origin of premating reproductive isolation continues to help elucidate the process of speciation and is the central event in the evolution of biological species. Therefore, during the process of species formation the diverging populations must acquire some means of reproductive isolation so that the genes from one gene pool are prevented from dispersing freely into a foreign gene pool. In the genus Drosophila, the phenomenon of behavioural reproductive isolation, which is an important type of premating (prezygotic) reproductive isolating mechanisms, has been extensively studied and interesting data have been documented. In many cases incomplete sexual isolation has been observed and the pattern and degree of isolation within and between the species have often been used to elucidate the phylogenetic relationships. The present review documents an overview of speciation mediated through behavioural incompatibility in different species groups of Drosophila with particular reference to the models proposed on the basis of one-sided ethological isolation to predict the direction of evolution. This study is crucial for understanding the mechanism of speciation through behavioural incompatibility and also for an understanding of speciation genetics in future prospects.

  6. Development and validation of stability-indicating HPLC method for simeltaneous determination of Lamivudine, Tenofovir, and Dolutegravir in bulk and their tablet dosage form

    Directory of Open Access Journals (Sweden)

    Nagasarapu Mallikarjuna Rao

    2015-12-01

    Conclusion: The proposed method was validated in terms of Linearity, Range, Accuracy, Precision, Specificity, Robustness and stability studies and the method is successfully applies to the estimation of Lamivudine, Tenofovir, and Dolutegravir in combined tablet dosage form.

  7. Selenium Metabolism in Cancer Cells: The Combined Application of XAS and XFM Techniques to the Problem of Selenium Speciation in Biological Systems

    Directory of Open Access Journals (Sweden)

    Hugh H. Harris

    2013-05-01

    Full Text Available Determining the speciation of selenium in vivo is crucial to understanding the biological activity of this essential element, which is a popular dietary supplement due to its anti-cancer properties. Hyphenated techniques that combine separation and detection methods are traditionally and effectively used in selenium speciation analysis, but require extensive sample preparation that may affect speciation. Synchrotron-based X-ray absorption and fluorescence techniques offer an alternative approach to selenium speciation analysis that requires minimal sample preparation. We present a brief summary of some key HPLC-ICP-MS and ESI-MS/MS studies of the speciation of selenium in cells and rat tissues. We review the results of a top-down approach to selenium speciation in human lung cancer cells that aims to link the speciation and distribution of selenium to its biological activity using a combination of X-ray absorption spectroscopy (XAS and X-ray fluorescence microscopy (XFM. The results of this approach highlight the distinct fates of selenomethionine, methylselenocysteine and selenite in terms of their speciation and distribution within cells: organic selenium metabolites were widely distributed throughout the cells, whereas inorganic selenium metabolites were compartmentalized and associated with copper. New data from the XFM mapping of electrophoretically-separated cell lysates show the distribution of selenium in the proteins of selenomethionine-treated cells. Future applications of this top-down approach are discussed.

  8. Selenium metabolism in cancer cells: the combined application of XAS and XFM techniques to the problem of selenium speciation in biological systems.

    Science.gov (United States)

    Weekley, Claire M; Aitken, Jade B; Finney, Lydia; Vogt, Stefan; Witting, Paul K; Harris, Hugh H

    2013-05-21

    Determining the speciation of selenium in vivo is crucial to understanding the biological activity of this essential element, which is a popular dietary supplement due to its anti-cancer properties. Hyphenated techniques that combine separation and detection methods are traditionally and effectively used in selenium speciation analysis, but require extensive sample preparation that may affect speciation. Synchrotron-based X-ray absorption and fluorescence techniques offer an alternative approach to selenium speciation analysis that requires minimal sample preparation. We present a brief summary of some key HPLC-ICP-MS and ESI-MS/MS studies of the speciation of selenium in cells and rat tissues. We review the results of a top-down approach to selenium speciation in human lung cancer cells that aims to link the speciation and distribution of selenium to its biological activity using a combination of X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (XFM). The results of this approach highlight the distinct fates of selenomethionine, methylselenocysteine and selenite in terms of their speciation and distribution within cells: organic selenium metabolites were widely distributed throughout the cells, whereas inorganic selenium metabolites were compartmentalized and associated with copper. New data from the XFM mapping of electrophoretically-separated cell lysates show the distribution of selenium in the proteins of selenomethionine-treated cells. Future applications of this top-down approach are discussed.

  9. Dissolved Mn Speciation and Ligand Characteristics in a Coastal Waterway

    Science.gov (United States)

    Oldham, V.; Jensen, L.; Luther, G. W., III

    2014-12-01

    Soluble manganese speciation (Mn(II) and Mn(III); 0.2 μm filtered) was measured along a salinity gradient in the Broadkill River, a coastal waterway bordered by wetlands and salt marshes in Delaware. We modified an established method of porphyrin (T-4(CP)P) addition, by incorporating a heating step and coupling a 100-cm cell to a UV/Vis detector, to achieve a 4.0 nM sample DL. Surface waters were collected from June to August, 2014 and total dissolved Mn (0.23 - 1.92 μM) first increased then decreased along the salinity gradient (31 ppt to freshwater). However, Mn speciation was highly variable; Mn(III) made up 0-49 % of the total dissolved Mn, where the highest Mn(III) values occurred at sites with high salt-marsh runoff. Mn(III) was not recoverable without the addition of a strong reducing agent, indicating that little or no weak ligand was present, and that a strong ligand was responsible for complexing Mn(III). An assessment of potential strong ligand character was made by precipitating humic matter, by acidifying subsamples to pHyellow color. Upon the addition of 500 μM desferrioxamine-B (DFOB) to the same sample, a peak at 310 nm appeared, indicating the formation of Mn(III)-DFOB. In acidified samples, the Mn(III)-pyrophosphate peak did not change. Humic matter, therefore, may be acting as an Mn(III) binding ligand, outcompeting pyrophosphate for Mn(III), however this natural ligand is outcompeted by a large excess of DFOB. The humic matter and increased Mn likely come from the salt marsh runoff during tidal exchange, and we observed that as salinity increased, the amount of humic binding decreased. These results present the first Mn speciation measurements along a salinity gradient in oxygenated waters.

  10. Study of the feasibility and precision in dose calculation with the method of bulk density assignment%容积密度分配法剂量计算可行性研究

    Institute of Scientific and Technical Information of China (English)

    秦颂兵; 周菊英; 龚唯; 吴承骏; 郭建; 陈龙; 詹蔚

    2013-01-01

    Objective To study investigate the dose accuracy that can be achieved with the method of bulk density assignment.Methods Sixteen cases of nasopharyngeal cancer patients and nineteen cases of esophageal cancer patients who accept radiotherapy in our department were selected.The planning CT images with bulk density assignment to different classes of tissues were applied to calculate the dose distributions,and then the resulting dose volume histograms (DVH) of the tumor and organs of risk were compared with the original treatment plan.The paired t-test was taken for dose comparison between two plans.Results The DVH comparison based on the planning CT and the bulk density assignment CT showed good agreements.With nasopharyngeal cancer patients,differences between the two plans about target and normal tissue were less than 1%.With esophageal cancer patients,the dose differences were less than 2%.Conclusion Preliminary results confirm that the bulk density assignment method can be applied to calculate the dose distributions.%目的 评估采用容积密度分配法进行剂量计算的可行性.方法 选取本科放疗的16例鼻咽癌和19例食管癌患者,对定位CT计划进行容积密度分配法重新制作计划,根据靶区和危及器官受量及剂量体积直方图比较新计划与原计划的剂量分布差异.两种计划的剂量比较行配对t检验.结果 采用容积密度分配法后的计划与定位CT计划相比靶区及危及器官剂量差异鼻咽癌患者均<1%、食管癌患者均<2%.结论 初步结果证实采用容积密度分配法可以进行剂量计算.

  11. Bulk Moisture and Salinity Sensor

    Science.gov (United States)

    Nurge, Mark; Monje, Oscar; Prenger, Jessica; Catechis, John

    2013-01-01

    Measurement and feedback control of nutrient solutions in plant root zones is critical to the development of healthy plants in both terrestrial and reduced-gravity environments. In addition to the water content, the amount of fertilizer in the nutrient solution is important to plant health. This typically requires a separate set of sensors to accomplish. A combination bulk moisture and salinity sensor has been designed, built, and tested with different nutrient solutions in several substrates. The substrates include glass beads, a clay-like substrate, and a nutrient-enriched substrate with the presence of plant roots. By measuring two key parameters, the sensor is able to monitor both the volumetric water content and salinity of the nutrient solution in bulk media. Many commercially available moisture sensors are point sensors, making localized measurements over a small volume at the point of insertion. Consequently, they are more prone to suffer from interferences with air bubbles, contact area of media, and root growth. This makes it difficult to get an accurate representation of true moisture content and distribution in the bulk media. Additionally, a network of point sensors is required, increasing the cabling, data acquisition, and calibration requirements. measure the dielectric properties of a material in the annular space of the vessel. Because the pore water in the media often has high salinity, a method to measure the media moisture content and salinity simultaneously was devised. Characterization of the frequency response for capacitance and conductance across the electrodes was completed for 2-mm glass bead media, 1- to 2-mm Turface (a clay like media), and 1- to 2-mm fertilized Turface with the presence of root mass. These measurements were then used to find empirical relationships among capacitance (C), the dissipation factor (D), the volumetric water content, and the pore water salinity.

  12. Analysis and stability of mercury speciation in petroleum hydrocarbons.

    Science.gov (United States)

    Bloom, N S

    2000-03-01

    Raw petroleum and natural gas often contain high concentrations of mercury, which can be damaging to the metal components of production facilities, as well as to the environment. Various Hg species have different properties in terms of mobility, reactivity and bioavailability. Thus, for cost-effective decisions regarding plant design, Hg extraction, and pollution control, speciation information must be available at the production facility. In this paper, a simple, wet chemical speciation method, which provides data on Hg(o), dissolved and particulate total Hg, Hg(II), and methyl Hg is presented. The method incorporates species-specific extraction and separation procedures, followed by cold vapor atomic fluorescence spectrometry (CVAFS). For each species, detection limits of approximately 0.1 ng/g were obtained. Storage experiments in various containers showed that organo-mercury species were stable for at least 30 days in all containers except those made of polyethylene; and Hg(o) was stable in all containers except those made of stainless steel or polyethylene. Hg(II) was rapidly lost from all containers except those made of aluminum, which rapidly converted it to Hg(o), which was stable. In general, most of the total Hg in petroleum products was particulate Hg, followed by dissolved Hg(II) and Hg(o). Sub-ng/g concentrations of methyl-Hg were observed in most samples.

  13. Detecting Hidden Diversification Shifts in Models of Trait-Dependent Speciation and Extinction.

    Science.gov (United States)

    Beaulieu, Jeremy M; O'Meara, Brian C

    2016-07-01

    The distribution of diversity can vary considerably from clade to clade. Attempts to understand these patterns often employ state-dependent speciation and extinction models to determine whether the evolution of a particular novel trait has increased speciation rates and/or decreased extinction rates. It is still unclear, however, whether these models are uncovering important drivers of diversification, or whether they are simply pointing to more complex patterns involving many unmeasured and co-distributed factors. Here we describe an extension to the popular state-dependent speciation and extinction models that specifically accounts for the presence of unmeasured factors that could impact diversification rates estimated for the states of any observed trait, addressing at least one major criticism of BiSSE (Binary State Speciation and Extinction) methods. Specifically, our model, which we refer to as HiSSE (Hidden State Speciation and Extinction), assumes that related to each observed state in the model are "hidden" states that exhibit potentially distinct diversification dynamics and transition rates than the observed states in isolation. We also demonstrate how our model can be used as character-independent diversification models that allow for a complex diversification process that is independent of the evolution of a character. Under rigorous simulation tests and when applied to empirical data, we find that HiSSE performs reasonably well, and can at least detect net diversification rate differences between observed and hidden states and detect when diversification rate differences do not correlate with the observed states. We discuss the remaining issues with state-dependent speciation and extinction models in general, and the important ways in which HiSSE provides a more nuanced understanding of trait-dependent diversification.

  14. Liquid phase microextraction for the analysis of trace elements and their speciation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bin, E-mail: binhu@whu.edu.cn; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated. - Highlights: • The state of art of LPME for trace elements and their speciation analysis is updated. • Different extraction formats of LPME are described. • The application potential and future

  15. Chromosomal Speciation in the Genomics Era: Disentangling Phylogenetic Evolution of Rock-wallabies

    Science.gov (United States)

    Potter, Sally; Bragg, Jason G.; Blom, Mozes P. K.; Deakin, Janine E.; Kirkpatrick, Mark; Eldridge, Mark D. B.; Moritz, Craig

    2017-01-01

    The association of chromosome rearrangements (CRs) with speciation is well established, and there is a long history of theory and evidence relating to “chromosomal speciation.” Genomic sequencing has the potential to provide new insights into how reorganization of genome structure promotes divergence, and in model systems has demonstrated reduced gene flow in rearranged segments. However, there are limits to what we can understand from a small number of model systems, which each only tell us about one episode of chromosomal speciation. Progressing from patterns of association between chromosome (and genic) change, to understanding processes of speciation requires both comparative studies across diverse systems and integration of genome-scale sequence comparisons with other lines of evidence. Here, we showcase a promising example of chromosomal speciation in a non-model organism, the endemic Australian marsupial genus Petrogale. We present initial phylogenetic results from exon-capture that resolve a history of divergence associated with extensive and repeated CRs. Yet it remains challenging to disentangle gene tree heterogeneity caused by recent divergence and gene flow in this and other such recent radiations. We outline a way forward for better integration of comparative genomic sequence data with evidence from molecular cytogenetics, and analyses of shifts in the recombination landscape and potential disruption of meiotic segregation and epigenetic programming. In all likelihood, CRs impact multiple cellular processes and these effects need to be considered together, along with effects of genic divergence. Understanding the effects of CRs together with genic divergence will require development of more integrative theory and inference methods. Together, new data and analysis tools will combine to shed light on long standing questions of how chromosome and genic divergence promote speciation. PMID:28265284

  16. Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection.

    Science.gov (United States)

    Liu, Jian; Bi, Shuping; Yang, Li; Gu, Xiaodong; Ma, Pengju; Gan, Ning; Wang, Xianlong; Long, Xiufeng; Zhang, Fuping

    2002-12-01

    The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.

  17. Validated stability-indicating high-performance thin-layer chromatographic method for estimation of cefpodoxime proxetil in bulk and in pharmaceutical formulation according to International conference on harmonization guidelines

    Directory of Open Access Journals (Sweden)

    Pritam Jain

    2012-01-01

    Full Text Available Aim: A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC method for analysis of cefpodoxime proxetil both in bulk and in pharmaceutical formulation has been developed and validated. Materials and Methods: The method employed HPTLC aluminum plates precoated with silica gel 60 RP-18 F 254 as the stationary phase. The solvent system consisted of toluene:methanol:chloroform (4:2:4 v/v. The system was found to give compact spot for cefpodoxime proxetil (R f value of 0.55 ± 0.02. Densitometric analysis of cefpodoxime proxetil was carried out in the absorbance mode at 289 nm. Results: The linear regression analysis data for the calibration plots showed good linear relationship, with r 2 = 0.998 ± 0.0015 with respect to peak area in the concentration range of 100-600 ng per spot. The mean value±SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 3.99 and 12.39 ng per spot, respectively. Cefpodoxime proxetil was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions, indicating that the drug is susceptible to both acid and base. The degraded product was well resolved from the pure drug, with significantly different R f value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of the investigated drug. Conclusion: The proposed HPTLC method can be applied for identification and quantitative determination of cefpodoxime proxetil in both bulk drug and pharmaceutical formulation.

  18. Foliar or root exposures to smelter particles: Consequences for lead compartmentalization and speciation in plant leaves

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, Eva [Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l' Agrobiopole, 31326 Castanet-Tolosan (France); CNRS, EcoLab, 31326 Castanet-Tolosan (France); Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue E. Belin, F-31400 Toulouse (France); Dappe, Vincent [LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d' Ascq Cedex (France); Sarret, Géraldine [ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble (France); Sobanska, Sophie [LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d' Ascq Cedex (France); Nowak, Dorota; Nowak, Jakub; Stefaniak, Elżbieta Anna [Department of Chemistry, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin (Poland); Magnin, Valérie [ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble (France); Ranieri, Vincent [CEA-INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Dumat, Camille, E-mail: camille.dumat@ensat.fr [Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l' Agrobiopole, 31326 Castanet-Tolosan (France); CNRS, EcoLab, 31326 Castanet-Tolosan (France)

    2014-04-01

    In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO{sub 4}, chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO{sub 3}. In rye-grass, the changes in Pb speciation were even more egregious: Pb–cell wall and Pb–organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to

  19. Optimization of parameters for the synthesis of Y2Cu2O5 nanoparticles by Taguchi method and comparison of their magnetic and optical properties with their bulk counterpart

    Science.gov (United States)

    Farbod, Mansoor; Rafati, Zahra; Shoushtari, Morteza Zargar

    2016-06-01

    Y2Cu2O5 nanoparticles were synthesized by sol-gel combustion method and effects of different factors on the size of nanoparticles were investigated. In order to reduce the experimental stages, Taguchi robust design method was employed. Acid citric:Cu+2 M ratio, pH, sintering temperature and time were chosen as the parameters for optimization. Among these factors the solution pH had the most influence and the others had nearly the same influence on the nanoparticles sizes. Based on the predicted conditions by Taguchi design, the sample with a minimum particle size of 47 nm was prepared. The magnetic behavior of Y2Cu2O5 nanoparticles were measured and found that at low fields they are soft ferromagnetic but at high fields they behave paramagnetically. The magnetic behavior of nanoparticles were compared to their bulk counterparts and found that the Mr of the samples was slightly different, but the Hc of the nanoparticles was 76% of the bulk sample. The maximum absorbance peak of UV-vis spectrum showed a blue shift for the smaller particles.

  20. Simple and rapid high performance liquid chromatography method for the determination of polidocanol as bulk product and in pharmaceutical polymer matrices using charged aerosol detection.

    Science.gov (United States)

    Ilko, David; Puhl, Sebastian; Meinel, Lorenz; Germershaus, Oliver; Holzgrabe, Ulrike

    2015-02-01

    Currently, neither the European nor the United States Pharmacopoeia provide a method for the determination of polidocanol (PD) content despite the fact that PD, besides being an excipient, is also used as an active pharmaceutical ingredient. We therefore developed a method where the PD content was determined using a Kinetex C18 column operated at 40°C with water-acetonitrile (15:85, v/v) as mobile phase. A Corona(®) charged aerosol detector was employed for the detection of PD that is lacking a suitable UV chromophore. The method was fully validated. Additionally, the method was applied for the determination of PD release from a pharmaceutical polymer matrix consisting of poly-ɛ-caprolactone and poly(lactic-co-glycolic acid) and PD.

  1. The Incredible Bulk

    CERN Document Server

    Fukushima, Keita; Kumar, Jason; Sandick, Pearl; Yamamoto, Takahiro

    2014-01-01

    Recent experimental results from the LHC have placed strong constraints on the masses of colored superpartners. The MSSM parameter space is also constrained by the measurement of the Higgs boson mass, and the requirement that the relic density of lightest neutralinos be consistent with observations. Although large regions of the MSSM parameter space can be excluded by these combined bounds, leptophilic versions of the MSSM can survive these constraints. In this paper we consider a scenario in which the requirements of minimal flavor violation, vanishing $CP$-violation, and mass universality are relaxed, specifically focusing on scenarios with light sleptons. We find a large region of parameter space, analogous to the original bulk region, for which the lightest neutralino is a thermal relic with an abundance consistent with that of dark matter. We find that these leptophilic models are constrained by measurements of the magnetic and electric dipole moments of the electron and muon, and that these models have ...

  2. Explosive bulk charge

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jacob Lee

    2015-04-21

    An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.

  3. A Validated HPLC Method for Simultaneous Determination of Perindopril Arginine, Amlodipine, and Indapamide: Application in Bulk and in Different Pharmaceutical Dosage Forms.

    Science.gov (United States)

    El-Bagary, Ramzia I; Elkady, Ehab F; Mowaka, Shereen; Attallah, Maria A

    2017-02-07

    A simple, accurate, and precise LC method with a reversed stationary phase was developed and validated for the determination of perindopril (PER) arginine, amlodipine (AML), and indapamide (IND) alone and in binary mixtures (PER arginine is found in two dosage forms, i.e., with either AML or IND). Chromatographic separation was carried out on a BDS Hypersil® C18 column (100 × 3 mm, 5 μm). The mobile phase, consisting of 0.05 M potassium dihydrogen phosphate buffer (pH 2.6)-methanol(50 + 50, v/v), was pumped through the column whose temperature was maintained at 50°C at a flow rate of 0.6 mL/min using isocratic elution, and UV detection at 215 nm was performed. Acceptable values of linearity, accuracy, and precision of the method were found over the concentration ranges of5-80 μg/mL PER, 2.5-80 μg/mL AML, and 0.5-20 μg/mLIND. The proposed chromatographic method was statistically compared to that of reference methods using one-way analysis of variance. The results showed that there was no significant difference between the methods. The developed method proved reliable for use in accurate QC of the drugs in their pharmaceutical preparations.

  4. VALIDATION OF RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF FEBUXOSTAT AND DICLOFENAC POTASSIUM IN BULK DRUG AND IN BI LAYER TABLET FORMULATION

    Directory of Open Access Journals (Sweden)

    Sanghvi Vaibhav

    2013-09-01

    Full Text Available A simple, rapid, accurate and precise isocratic reverse phase high performance liquid chromatography (RP-HPLC method has been developed for simultaneous estimation of febuxostat and diclofenac potassium in combined dosage form by using phenomenex C18 column (stationary phase having dimension of 4.6 × 250 mm and particle size of 5 μm and mobile phase containing a mixture of 0.02 M potassium dihydrogen orthophosphate buffer (adjusted to pH 7 with sodium hydroxide: acetonitrile: methanol (35:9:56 v/v/v at a flow rate of 1 ml/min and detection was carried out at 290 nm. The retention times of febuxostat and diclofenac potassium were 6.01 ± 0.02 minutes and 7.10 ± 0.02 minutes respectively. The developed method was validated as per ICH guideline for specificity, linearity, accuracy and precision, limit of detection and limit of quantification. Linearity studies for the developed method were found in the range of 5 to 30 μg/ml for febuxostat and 12.5 to 75 μg/ml for diclofenac potassium respectively. The accuracy of the method was studied by recovery study and found to be in the range of 98 % - 102 %. The % RSD for intraday and inter day precision was found less than 2. The new RP-HPLC method was successfully applied to marketed formulation of Febuxostat and Diclofenac potassium without any interference from excipients.

  5. Speciation Effect in the Penna Aging Model

    Science.gov (United States)

    Łaszkiewicz, A.; Szymczak, Sz.; Cebrat, S.

    We have simulated the evolution of diploid, sexually reproducing populations using the Penna model of aging. We have noted that diminishing the recombination frequency during the gamete production generates a specific diversity of genomes in the populations. When two populations independently evolving for some time were mixed in one environmental niche of the limited size and crossbreeding between them was allowed, the average lifespan of hybrids was significantly shorter than the lifespan of the individuals of parental lines. Another effect of higher hybrid mortality is the faster elimination of one parental line from the shared environment. The two populations living in one environment co-exist much longer if they are genetically separated — they compete as two species instead of crossbreeding. This effect can be considered as the first step to speciation — any barrier eliminating crossbreeding between these populations, leading to speciation, would favor the populations.

  6. Speciation in aqueous solutions of nitric acid.

    Science.gov (United States)

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments.

  7. Does speciation matter for tungsten ecotoxicology?

    Science.gov (United States)

    Strigul, Nikolay

    2010-09-01

    Tungsten is a widely used transition metal that has not been thoroughly investigated with regards to its ecotoxicological effects. Tungsten anions polymerize in environmental systems as well as under physiological conditions in living organisms. These polymerization/condensation reactions result in the development of several types of stable polyoxoanions. Certain chemical properties (in particular redox and acidic properties) differentiate these polyanions from monotungstates. However, our current state of knowledge on tungsten toxicology, biological and environmental effects is based entirely on experiments where monotungstates were used and assumed by the authors to be the form of tungsten that was present and that produced the observed effect. Recent discoveries indicate that tungsten speciation may be important to ecotoxicology. New results obtained by different research groups demonstrate that polytungstates develop and persist in environmental systems, and that polyoxotungstates are much more toxic than monotungstates. This paper reviews the available toxicological information from the standpoint of tungsten speciation and identifies knowledge gaps and pertinent future research directions.

  8. Speciation of potentially mobile Si in Yangtze Estuary surface sediments: estimates using a modified sequential extraction technique.

    Science.gov (United States)

    Zhu, Huagang; Wang, Chao; Wang, Peifang; Hou, Jun; Qian, Jin; Ao, Yanhui; Liu, Cui

    2016-09-01

    To improve our understanding of the Si-related biogeochemical processes that occur in estuarine ecosystems with large subaqueous deltas (e.g., the Yangtze Estuary; YE), the speciation of Si in the surface sediments of the YE was investigated. The relationships between the different Si species and sediment bulk parameters were also discussed. Based on modified sequential extraction method, we can successfully estimate the following five sedimentary potentially mobile Si pools: weak acid leachable Si (W-Si); Si bound to organic matter (H-Si); Si coprecipitated with amorphous Fe/Al oxides (O-Si); Si coprecipitated with crystalline Fe/Al oxides (Ouv-Si), and biogenic silica (B-Si). The total potentially mobile Si pool (T-Si) ranged between 1689.31 and 5487.10 μg/g, with high values observed in deltaic mud deposits. The Si fractions were closely correlated with grain size compositions, except for O-Si. In deltaic mud deposits, efficient loss of organic matters and recycling of Fe oxides probably resulted in the amorphous or poorly crystalline Fe oxides uncoupled with the clay fractions, and thus leading to the lack of correlation between O-Si and grain size. As compared with Ouv-Si, the O-Si should possess stronger mobility, which highlights the importance of quantifying the O-Si pool in deltaic sediments.

  9. Speciation in arctic and alpine diploid plants

    OpenAIRE

    Gustafsson, A Lovisa S

    2013-01-01

    The main objectives of this thesis are to study patterns and processes of plant speciation in arctic and alpine diploid plants. Cryptic species are here referred to as morphologically similar individuals belonging to the same taxonomic species but that are unable to produce fertile offspring (i.e. 'sibling' species). The arctic flora is considered as one of the most species-poor floras of the world, and the latitudinal gradient with decreasing diversity from low to high latitudes is likely...

  10. Development and Validation of a Stability-Indicating HPTLC Method for Analysis of Rasagiline Mesylate in the Bulk Drug and Tablet Dosage Form

    Directory of Open Access Journals (Sweden)

    Singaram Kathirvel

    2012-01-01

    Full Text Available A simple and sensitive thin-layer chromatographic method has been established for analysis of rasagiline mesylate in pharmaceutical dosage form. Chromatography on silica gel 60 F254 plates with 6 : 1 : 2(v/v/v butanol-methanol water as mobile phase furnished compact spots at Rf  0.76±0.01. Densitometric analysis was performed at 254 nm. To show the specificity of the method, rasagiline mesylate was subjected to acid, base, neutral hydrolysis, oxidation, photolysis, and thermal decomposition, and the peaks of degradation products were well resolved from that of the pure drug. Linear regression analysis revealed a good linear relationship between peak area and amount of rasagiline mesylate in the range of 100–350 ng/band. The minimum amount of rasagiline mesylate that could be authentically detected and quantified was 11.12 and 37.21 ng/band, respectively. The method was validated, in accordance with ICH guidelines for precision, accuracy, and robustness. Since the method could effectively separate the drug from its degradation products, it can be regarded as stability indicating.

  11. Speciation and Localization of Arsenic in White and Brown Rice Grains

    Energy Technology Data Exchange (ETDEWEB)

    Meharg, Andrew A.; Lombi, Enzo; Williams, Paul N.; Scheckel, Kirk G.; Feldmann, Joerg; Raab, Andrea; Zhu, Yongguan; Islam, Rafiql (EPA); (Bangladesh); (UCopenhagen); (Aberdeen); (Chinese Aca. Sci.)

    2008-06-30

    Synchrotron-based X-ray fluorescence (S-XRF) was utilized to locate arsenic (As) in polished (white) and unpolished (brown) rice grains from the United States, China, and Bangladesh. In white rice As was generally dispersed throughout the grain, the bulk of which constitutes the endosperm. In brown rice As was found to be preferentially localized at the surface, in the region corresponding to the pericarp and aleurone layer. Copper, iron, manganese, and zinc localization followed that of arsenic in brown rice, while the location for cadmium and nickel was distinctly different, showing relatively even distribution throughout the endosperm. The localization of As in the outer grain of brown rice was confirmed by laser ablation ICP?MS. Arsenic speciation of all grains using spatially resolved X-ray absorption near edge structure (?-XANES) and bulk extraction followed by anion exchange HPLC?ICP?MS revealed the presence of mainly inorganic As and dimethylarsinic acid (DMA). However, the two techniques indicated different proportions of inorganic:organic As species. A wider survey of whole grain speciation of white (n = 39) and brown (n = 45) rice samples from numerous sources (field collected, supermarket survey, and pot trials) showed that brown rice had a higher proportion of inorganic arsenic present than white rice. Furthermore, the percentage of DMA present in the grain increased along with total grain arsenic.

  12. Speciation of sulfur in biochar produced from pyrolysis and gasification of oak and corn stover.

    Science.gov (United States)

    Cheah, Singfoong; Malone, Shealyn C; Feik, Calvin J

    2014-01-01

    The effects of feedstock type and biomass conversion conditions on the speciation of sulfur in biochars are not well-known. In this study, the sulfur content and speciation in biochars generated from pyrolysis and gasification of oak and corn stover were determined. We found the primary determinant of the total sulfur content of biomass to be the feedstock from which the biochar is generated, with oak and corn stover biochars containing 160 and 600-800 ppm sulfur, respectively. In contrast, for sulfur speciation, we found the primary determinant to be the temperature combined with the thermochemical conversion method. The speciation of sulfur in biochars was determined using X-ray absorption near-edge structure (XANES), ASTM method D2492, and scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). Biochars produced under pyrolysis conditions at 500-600 °C contain sulfate, organosulfur, and sulfide. In some cases, the sulfate contents are up to 77-100%. Biochars produced in gasification conditions at 850 °C contain 73-100% organosulfur. The increase of the organosulfur content as the temperature of biochar production increases suggests a similar sulfur transformation mechanism as that in coal, where inorganic sulfur reacts with hydrocarbon and/or H2 to form organosulfur when the coal is heated. EDS mapping of a biochar produced from corn stover pyrolysis shows individual sulfur-containing mineral particles in addition to the sulfur that is distributed throughout the organic matrix.

  13. Arsenic speciation and sorption in natural environments

    Science.gov (United States)

    Campbell, Kate M.; Nordstrom, D. Kirk

    2014-01-01

    Aqueous arsenic speciation, or the chemical forms in which arsenic exists in water, is a challenging, interesting, and complicated aspect of environmental arsenic geochemistry. Arsenic has the ability to form a wide range of chemical bonds with carbon, oxygen, hydrogen, and sulfur, resulting in a large variety of compounds that exhibit a host of chemical and biochemical properties. Besides the intriguing chemical diversity, arsenic also has the rare capacity to capture our imaginations in a way that few elements can duplicate: it invokes images of foul play that range from sinister to comedic (e.g., “inheritance powder” and arsenic-spiked elderberry wine). However, the emergence of serious large-scale human health problems from chronic arsenic exposure in drinking water has placed a high priority on understanding environmental arsenic mobility, toxicity, and bioavailability, and chemical speciation is key to these important questions. Ultimately, the purpose of arsenic speciation research is to predict future occurrences, mitigate contamination, and provide successful management of water resources.

  14. The genetics of speciation by reinforcement.

    Directory of Open Access Journals (Sweden)

    Daniel Ortiz-Barrientos

    2004-12-01

    Full Text Available Reinforcement occurs when natural selection strengthens behavioral discrimination to prevent costly interspecies matings, such as when matings produce sterile hybrids. This evolutionary process can complete speciation, thereby providing a direct link between Darwin's theory of natural selection and the origin of new species. Here, by examining a case of speciation by reinforcement in Drosophila,we present the first high-resolution genetic study of variation within species for female mating discrimination that is enhanced by natural selection. We show that reinforced mating discrimination is inherited as a dominant trait, exhibits variability within species, and may be influenced by a known set of candidate genes involved in olfaction. Our results show that the genetics of reinforced mating discrimination is different from the genetics of mating discrimination between species, suggesting that overall mating discrimination might be a composite phenomenon, which in Drosophila could involve both auditory and olfactory cues. Examining the genetics of reinforcement provides a unique opportunity for both understanding the origin of new species in the face of gene flow and identifying the genetic basis of adaptive female species preferences, two major gaps in our understanding of speciation.

  15. Development of superconductor bulk for superconductor bearing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong (and others)

    2008-08-15

    Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C {approx} 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm{sup 2} using TSMG processing technique.

  16. Development and Validation of Reverse-phase High-performance Liquid Chromatography Method for Estimation of Citicoline Sodium in Bulk and Dosage Form.

    Science.gov (United States)

    Maradiya, H K; Pansara, Vasundhara H

    2013-03-01

    A simple, accurate, precise and sensitive reverse-phase high-performance liquid chromatography method for the determination of citicoline sodium has been developed and validated. Drug was resolved on a C18 column (Phenomenex Luna, 250×4.6 mm, 10μ), utilizing mobile phase of potassium dihydrogen phosphate buffer and acetonitrile in a ratio of 30:70. Mobile phase was delivered at the flow rate of 1.0 ml/min and detection was carried out at 272 nm. Separation was completed within 2.22 min. Calibration curve was linear with good correlation coefficient (R(2)=0.999) over a concentration range 10-60 μg/ml. Recovery was between 98.84 and 101.76%. Method was found to be reproducible with relative standard deviation for intra and interday precision of <2.0% over the said concentration range. The method was successfully applied to the determination of the citicoline sodium, it can be very useful and an alternate to performing the stability studies.

  17. Stability Indicating RP-HPLC Method Development and Validation of Simultaneous Estimation of Trandolapril and Verapamil Hydrochloride with Forced Degradation Studies in Bulk and Commercial Products

    Directory of Open Access Journals (Sweden)

    Ganipisetty Lakshmi Aswini

    2015-11-01

    Full Text Available A simple reproducible and efficient isocratic reversed-phase high-performance liquid chromatographic (RP-HPLC method has been developed and validated for the simultaneous estimation of Trandolapril and Verapamil. All the drugs were separated on an Inertsil ODS – 3V 150 x 4.6mm, 5µm. The mobile phase, optimized through an experimental design, was a 40:60 (v/v mixture of acetonitrile and triethylamine buffer (pH 3.0 , pumped at a flow rate of 1.3 ml/min. UV detection was performed at 216 nm. The retention time of Verapamil Hydrochloride and Trandolapril was found to be 1.51 min and 3.43 min respectively. The method was validated in the sample concentration ranges of 1.6 - 25µg/ml for Trandolapril and 95-1530µg/ml for Verapamil Hydrochloride, The method demonstrated to be robust, resisting to small deliberate changes in pH and flow rate of the mobile phase. The LOD values were 0.26 µg/ml and 10.3 µg/ml, while the LOQ values were 0.87 µg/ml and 31.1 µg/ml for Trandolapril and Verapamil Hydrochloride respectively. The recoveries for all three levels were above 99%.

  18. Validated HPTLC and Stability Indicating RP-HPLC Methods for the Simultaneous Estimation of Moxifloxacin and Dexamethasone in Bulk and Ophthalmic Dosage Form

    Directory of Open Access Journals (Sweden)

    B. Mohan Gandhi

    2016-08-01

    Full Text Available Novel HPTLC and stability indicating RP-HPLC methods were developed for simultaneous estimation of Moxifloxacin (MOX and Dexamethasone (DEX in ophthalmic dosage form. For HPTLC method, the separation was carried out on HPTLC aluminum plates using acetonitrile:water:ammonia (8:1:0.5 v/v/v as mobile phase and developed plates were read at 266 nm. The drugs were resolved satisfactorily with Rf values of 0.09±0.01 and 0.74±0.01 for MOX and DEX, respectively. The RP-HPLC analysis is carried out on Shiseido C18 column (250 mm × 4.6 mm I.D., 5 µm, using 0.02M acetate buffer (pH is 4 adjusted with triethylamine and acetonitrile in the ratio of 60:40 v/v with a flow rate of 1.2 m/min and the detection was carried out at 254 nm. The retention times were found to be 2.144±0.5 min and 4.732±0.5 min. for MOX and DEX respectively. Developed methods were validated as per ICH guidelines and were found to be within the limits.

  19. Utility of Hantzsch reaction for development of highly sensitive spectrofluorimetric method for determination of alfuzosin and terazosin in bulk, dosage forms and human plasma.

    Science.gov (United States)

    Hammad, Mohamed A; Omar, Mahmoud A; Salman, Baher I

    2017-03-17

    A highly sensitive, cheap, simple and accurate spectrofluorimetric method has been developed and validated for the determination of alfuzosin hydrochloride and terazosin hydrochloride in their pharmaceutical dosage forms and in human plasma. The developed method is based on the reaction of the primary amine moiety in the studied drugs with acetylacetone and formaldehyde according to the Hantzsch reaction, producing yellow fluorescent products that can be measured spectrofluorimetrically at 480 nm after excitation at 415 nm. Different experimental parameters affecting the development and stability of the reaction products were carefully studied and optimized. The fluorescence-concentration plots of alfuzosin and terazosin were rectilinear over a concentration range of 70-900 ng ml(-1) , with quantitation limits 27.1 and 32.2 ng ml(-1) for alfuzosin and terazosin, respectively. The proposed method was validated according to ICH guidelines and successfully applied to the analysis of the investigated drugs in dosage forms, content uniformity test and spiked human plasma with high accuracy.

  20. Development and validation of reverse-phase high-performance liquid chromatography method for estimation of citicoline sodium in bulk and dosage form

    Directory of Open Access Journals (Sweden)

    H K Maradiya

    2013-01-01

    Full Text Available A simple, accurate, precise and sensitive reverse-phase high-performance liquid chromatography method for the determination of citicoline sodium has been developed and validated. Drug was resolved on a C18 column (Phenomenex Luna, 250×4.6 mm, 10μ, utilizing mobile phase of potassium dihydrogen phosphate buffer and acetonitrile in a ratio of 30:70. Mobile phase was delivered at the flow rate of 1.0 ml/min and detection was carried out at 272 nm. Separation was completed within 2.22 min. Calibration curve was linear with good correlation coefficient (R 2 =0.999 over a concentration range 10-60 μg/ml. Recovery was between 98.84 and 101.76%. Method was found to be reproducible with relative standard deviation for intra and interday precision of <2.0% over the said concentration range. The method was successfully applied to the determination of the citicoline sodium, it can be very useful and an alternate to performing the stability studies.

  1. Stability-indicating UHPLC method for determination of nevirapine in its bulk form and tablets: identification of impurities and degradation kinetic study.

    Science.gov (United States)

    Reis, Naialy Fernandes Araújo; de Assis, Jéssica Camille; Fialho, Sílvia Ligório; Pianetti, Gerson Antônio; Fernandes, Christian

    2016-07-15

    Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, is a drug widely used in the treatment of Acquired Immunodeficiency Syndrome (AIDS). The evaluation of NVP stability is of fundamental importance in order to guarantee drug product efficacy, safety and quality. In this study, NVP active pharmaceutical ingredient (API) and tablets were subjected to a detailed study of forced degradation, employing several degrading agents (acid, alkaline, water, metal ions, humidity, heat, light and oxidation agents). In order to determine NVP and the degradation products formed, a stability-indicating UHPLC method using fused core column was developed and validated. The separation was carried out using a Poroshell 120C18 column (100×2.1mm i.d.; 2.7μm particle size) and the mobile phase was composed of acetonitrile and water in a gradient elution, at a flow rate of 0.2ml/min. Chemical structures and mechanisms for the formation of three degradation products were proposed by means of LC/MS-MS. Also, NVP degradation kinetic was studied and its order of degradation evaluated. NVP was degraded in acidic and oxidative conditions and the degradation profile for NVP tablets and API were similar. The stability-indicating method proved to be selective for NVP and its degradation products. Calibration curve was linear in the range of 8-48μg/ml and the method showed to be precise, accurate and robust for both NVP API and tablets, with detection and quantification limits of 0.092μg/ml and 0.174μg/ml, respectively.

  2. Comparison of preparation methods for ceria catalyst and the effect of surface and bulk sulfates on its activity toward NH3-SCR.

    Science.gov (United States)

    Chang, Huazhen; Ma, Lei; Yang, Shijian; Li, Junhua; Chen, Liang; Wang, Wei; Hao, Jiming

    2013-11-15

    A series of CeO2 catalysts prepared with sulfate (S) and nitrate (N) precursors by hydrothermal (H) and precipitation (P) methods were investigated in selective catalytic reduction of NOx by NH3 (NH3-SCR). The catalytic activity of CeO2 was significantly affected by the preparation methods and the precursor type. CeO2-SH, which was prepared by hydrothermal method with cerium (IV) sulfate as a precursor, showed excellent SCR activity and high N2 selectivity in the temperature range of 230-450 °C. Based on the results obtained by temperature-programmed reduction (H2-TPR), transmission infrared spectra (IR) and thermal gravimetric analysis (TGA), the excellent performance of CeO2-SH was correlated with the surface sulfate species formed in the hydrothermal reaction. These results indicated that sulfate species bind with Ce(4+) on the CeO2-SH catalyst, and the specific sulfate species, such as Ce(SO4)2 or CeOSO4, were formed. The adsorption of NH3 was promoted by these sulfate species, and the probability of immediate oxidation of NH3 to N2O on Ce(4+) was reduced. Accordingly, the selective oxidation of NH3 was enhanced, which contributed to the high N2 selectivity in the SCR reaction. However, the location of sulfate on the CeO2-SP catalyst was different. Plenty of sulfate species were likely deposited on CeO2-SP surface, covering the active sites for NO oxidation, which resulted in poor SCR activity in the test temperature range. Moreover, the resistance to alkali metals, such as Na and K, was improved over the CeO2-SH catalyst.

  3. Study on Effect of Gd (III) Speciation on Ca (II) Speciation in Human Blood Plasma by Computer Simulation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ca (II) speciation and effect of Gd (III) speciation on Ca (II) speciation in human blood plasma were studied by computer simulation. [CaHCO3]+ is a predominant compound species of Ca (II). Gd (III) can compete with Ca (II) for biological molecules. The presence of Gd (III) results in a increase of concentration of free Ca (II) and a decrease of concentration of Ca (II) compounds.

  4. Chromium speciation in solid matrices and regulation: a review

    Energy Technology Data Exchange (ETDEWEB)

    Unceta, N. [University of the Basque Country, Department of Analytical Chemistry, Faculty of Pharmacy, Vitoria-Gasteiz (Spain); Seby, F. [Ultra Traces Analyses Aquitaine (UT2A), Helioparc Pau-Pyrenees, Pau (France); Malherbe, J.; Donard, O.F.X. [Universite de Pau et des Pays de l' Adour, Helioparc Pau-Pyrenees, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM, UMR CNRS 5254, Pau (France)

    2010-06-15

    In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na{sub 2}CO{sub 3} solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future. (orig.)

  5. Primate extinction risk and historical patterns of speciation and extinction in relation to body mass.

    Science.gov (United States)

    Matthews, Luke J; Arnold, Christian; Machanda, Zarin; Nunn, Charles L

    2011-04-22

    Body mass is thought to influence diversification rates, but previous studies have produced ambiguous results. We investigated patterns of diversification across 100 trees obtained from a new Bayesian inference of primate phylogeny that sampled trees in proportion to their posterior probabilities. First, we used simulations to assess the validity of previous studies that used linear models to investigate the links between IUCN Red List status and body mass. These analyses support the use of linear models for ordinal ranked data on threat status, and phylogenetic generalized linear models revealed a significant positive correlation between current extinction risk and body mass across our tree block. We then investigated historical patterns of speciation and extinction rates using a recently developed maximum-likelihood method. Specifically, we predicted that body mass correlates positively with extinction rate because larger bodied organisms reproduce more slowly, and body mass correlates negatively with speciation rate because smaller bodied organisms are better able to partition niche space. We failed to find evidence that extinction rates covary with body mass across primate phylogeny. Similarly, the speciation rate was generally unrelated to body mass, except in some tests that indicated an increase in the speciation rate with increasing body mass. Importantly, we discovered that our data violated a key assumption of sample randomness with respect to body mass. After correcting for this bias, we found no association between diversification rates and mass.

  6. Macroevolutionary speciation rates are decoupled from the evolution of intrinsic reproductive isolation in Drosophila and birds.

    Science.gov (United States)

    Rabosky, Daniel L; Matute, Daniel R

    2013-09-17

    The rate at which speciation occurs varies greatly among different kinds of organisms and is frequently assumed to result from species- or clade-specific factors that influence the rate at which populations acquire reproductive isolation. This premise leads to a fundamental prediction that has never been tested: Organisms that quickly evolve prezygotic or postzygotic reproductive isolation should have faster rates of speciation than organisms that slowly acquire reproductive isolation. We combined phylogenetic estimates of speciation rates from Drosophila and birds with a method for analyzing interspecific hybridization data to test whether the rate at which individual lineages evolve reproductive isolation predicts their macroevolutionary rate of species formation. We find that some lineages evolve reproductive isolation much more quickly than others, but this variation is decoupled from rates of speciation as measured on phylogenetic trees. For the clades examined here, reproductive isolation--especially intrinsic, postzygotic isolation--does not seem to be the rate-limiting control on macroevolutionary diversification dynamics. These results suggest that factors associated with intrinsic reproductive isolation may have less to do with the tremendous variation in species diversity across the evolutionary tree of life than is generally assumed.

  7. Development and validation of a single RP-HPLC assay method for analysis of bulk raw material batches of four parabens that are widely used as preservatives in pharmaceutical and cosmetic products.

    Science.gov (United States)

    Kumar, S; Mathkar, S; Romero, C; Rustum, A M

    2011-05-01

    A stability-indicating, robust, fast, and user friendly reversed-phase high-performance liquid chromatographic (RP-HPLC) assay method has been developed and validated for the analysis of commercial raw material batches of methylparaben, ethylparaben, propylparaben, and butylparaben. These four parabens are widely used as preservatives in pharmaceutical and cosmetic products. Accurate assay value of each of the parabens in their respective commercial lots is critical to determine the correct weight of the paraben that is needed to obtain the target concentration of the paraben in a specific lot of pharmaceutical or cosmetic products. Currently, there are no single HPLC assay methods (validated as per ICH requirements) available in the literature that can be used to analyze the commercial lots of each of the four parabens. The analytical method reported herein analyzes all four parabens in less than 10 min. The method presented in this report was successfully validated as per ICH guidelines. Therefore, this method can be implemented in QC laboratories to analyze and assay the commercial bulk lots of the four parabens.

  8. Can bulk viscosity drive inflation

    Energy Technology Data Exchange (ETDEWEB)

    Pacher, T.; Stein-Schabes, J.A.; Turner, M.S.

    1987-09-15

    Contrary to other claims, we argue that bulk viscosity associated with the interactions of non- relativistic particles with relativistic particles around the time of the grand unified theory (GUT) phase transition cannot lead to inflation. Simply put, the key ingredient for inflation, negative pressure, cannot arise due to the bulk-viscosity effects of a weakly interacting mixture of relativistic and nonrelativistic particles.

  9. Brane Couplings from Bulk Loops

    OpenAIRE

    Georgi, Howard; Grant, Aaron K.; Hailu, Girma

    2000-01-01

    We compute loop corrections to the effective action of a field theory on a five-dimensional $S_1/Z_2$ orbifold. We find that the quantum loop effects of interactions in the bulk produce infinite contributions that require renormalization by four-dimensional couplings on the orbifold fixed planes. Thus bulk couplings give rise to renormalization group running of brane couplings.

  10. Speciation and recovery of chromium from chromite ore processing residues.

    Science.gov (United States)

    Sreeram, K J; Ramasami, T

    2001-10-01

    The processing of chromite ore is associated with the generation of large quantities of solid wastes containing chromium, which have been disposed of as landfill for many years. The mobilization and operational speciation of chromium contained in soils contaminated with metal salts are important in terms of the environment. Several methods have been employed for the extraction and recovery of solid wastes. Chromium contained in contaminated soils and solid wastes can be categorized as exchangeable, oxidizable, carbonate-bound, reducible and residual. The results from this study indicate a need for efficient leaching methodologies in chromite ore processing plants to decrease the non-detrital fractions of chromium in the residue. Aggressive methodologies are required to recover chromium from the detrital fractions. The potential benefits of employing sodium peroxide for the complete recovery of chromium from chromite residue have been demonstrated, and the need to ensure the safety of the process has been emphasized.

  11. Arsenic speciation in solids using X-ray absorption spectroscopy

    Science.gov (United States)

    Foster, Andrea L.; Kim, Chris S.

    2014-01-01

    Synchrotron-based X-ray absorption spectroscopy (XAS) is an in situ, minimally-destructive, element-specific, molecular-scale structural probe that has been employed to study the chemical forms (species) of arsenic (As) in solid and aqueous phases (including rocks, soils, sediment, synthetic compounds, and numerous types of biota including humans) for more than 20 years. Although several excellent reviews of As geochemistry and As speciation in the environment have been published previously (including recent contributions in this volume), the explosion of As-XAS studies over the past decade (especially studies employing microfocused X-ray beams) warrants this new review of the literature and of data analysis methods.

  12. Speciation and bio-availability of copper in Lake Tjeukemeer.

    NARCIS (Netherlands)

    Verweij, W.

    1991-01-01

    Chapter 1: introductionIn this thesis an account is given of a research project dealing with the chemical speciation and bioavailability of copper in Lake Tjeukemeer, a lake in the north of the Netherlands. The reason for the initiation of this project was a lack of knowledge about the speciation of

  13. The neutral theory of biodiversity with random fission speciation

    NARCIS (Netherlands)

    Etienne, Rampal S.; Haegeman, Bart

    2011-01-01

    The neutral theory of biodiversity and biogeography emphasizes the importance of dispersal and speciation to macro-ecological diversity patterns. While the influence of dispersal has been studied quite extensively, the effect of speciation has not received much attention, even though it was already

  14. Speciation and release kinetics of zinc in contaminated paddy soils

    Science.gov (United States)

    Zinc is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation of Zn is controlled by many factors, especially soil pH and Eh, which can vary in lowland rice culture. This study determined Zn speciation and release kinetics in Cd-Zn co-contamina...

  15. Sympatric speciation in structureless environments Theories and models

    NARCIS (Netherlands)

    Getz, Wayne M.; Salter, Richard; Seidel, Dana Paige; Hooft, Van Pim

    2016-01-01

    Background: Darwin and the architects of the Modern Synthesis found sympatric speciation difficult to explain and suggested it is unlikely to occur. Increasingly, evidence over the past few decades suggest that sympatric speciation can occur under ecological conditions that require at most intras

  16. Coevolutionary immune system dynamics driving pathogen speciation.

    Directory of Open Access Journals (Sweden)

    Kimberly J Schlesinger

    Full Text Available We introduce and analyze a within-host dynamical model of the coevolution between rapidly mutating pathogens and the adaptive immune response. Pathogen mutation and a homeostatic constraint on lymphocytes both play a role in allowing the development of chronic infection, rather than quick pathogen clearance. The dynamics of these chronic infections display emergent structure, including branching patterns corresponding to asexual pathogen speciation, which is fundamentally driven by the coevolutionary interaction. Over time, continued branching creates an increasingly fragile immune system, and leads to the eventual catastrophic loss of immune control.

  17. Performance and applications of quench melt-growth bulk magnets

    Science.gov (United States)

    Nariki, S.; Teshima, H.; Morita, M.

    2016-03-01

    This paper describes the progress in quench melt-growth (QMG) bulk magnets, developed by the Nippon Steel & Sumitomo Metal Corporation, which consist of single crystalline RE123 phase and finely dispersed RE211 particles. QMG bulks can trap high magnetic fields. The field-trapping ability of QMG bulks is largely increased with an improvement in its J c and size, promising the realization of various applications such as flywheel energy-storage systems, ship motors, NMR/MRI spectrometers, wind-power generators and so on. Intensive research has revealed that the optimal RE element is different depending on application requirements. Gd-QMG bulk is the most promising material for several high-field engineering applications. The trapped magnetic field of Gd-QMG bulk 60 mm in diameter at 77 K is twice as large as that of Y-QMG bulk with a similar size due to its excellent J c properties. The large Gd-based QMG bulks up to 150 mm in diameter are fabricated by incorporating the RE compositional gradient method. Compact NMR/MRI spectrometers are one of the promising applications of bulk superconductors. Eu-QMG bulks are suitable for NMR magnets. NMR applications require extremely homogeneous magnetic fields. In the Eu-system, the small paramagnetic moment of a Eu ion compared to a Gd ion improves the field homogeneity in the bulk. For the application of current leads, Dy-based QMG is available by utilizing a low thermal conductivity.

  18. Comparison of Implementation Methods for State Analysis of Bulk Power System Reliability%大电网可靠性评估状态分析实现方法的比较

    Institute of Scientific and Technical Information of China (English)

    陈凡; 卫志农; 黄正; 孙国强; 张雪娇

    2016-01-01

    系统状态分析是影响大电网可靠性评估计算效率的关键环节,基于此对系统状态分析的具体实现方法进行了比较研究。介绍了大电网可靠性分析的原理,对系统状态分析中包含的网络拓扑分析、断线潮流计算、最优负荷削减量的计算等步骤的实现方法进行了分析,以RBTS、IEEE RTS79和IEEE RTS96等可靠性测试系统为例进行了算例分析。算例结果表明:节点标记法能更快地进行系统解列判断;利用故障前的节点阻抗矩阵和故障线路信息能够更加快速地计算系统的直流断线潮流;应根据系统规模和复杂性,选择合适的数学模型和优化算法来计算系统的最优负荷削减量。%System state analysis is the key procedure affecting the calculation efficiency of bulk power system reliabili⁃ty. The implementation methods of steps in state analysis are studied comparatively in this paper. The principle of bulk power system reliability is reviewed,and the implementation methods for state analysis are analyzed,including network topology analysis,line-outage power flow calculation and optimal load curtailment. Finally,a series of case studies are carried out on reliability test systems,such as RBTS,IEEE RTS79 and IEEE RTS 96. Results of case studies show that node notation method can conduct the network connectivity analysis more rapidly,the fast algorithm which is on the ba⁃sis of node impedance matrix of normal system state and the information of fault lines can be used to calculate the line-outage power flow more effectively,and appropriate mathematical model and optimal method should be chosen to calcu⁃late the optimal load curtailment according to the system scale and complexity.

  19. Ephemeral ecological speciation and the latitudinal biodiversity gradient.

    Science.gov (United States)

    Cutter, Asher D; Gray, Jeremy C

    2016-10-01

    The richness of biodiversity in the tropics compared to high-latitude parts of the world forms one of the most globally conspicuous patterns in biology, and yet few hypotheses aim to explain this phenomenon in terms of explicit microevolutionary mechanisms of speciation and extinction. We link population genetic processes of selection and adaptation to speciation and extinction by way of their interaction with environmental factors to drive global scale macroecological patterns. High-latitude regions are both cradle and grave with respect to species diversification. In particular, we point to a conceptual equivalence of "environmental harshness" and "hard selection" as eco-evolutionary drivers of local adaptation and ecological speciation. By describing how ecological speciation likely occurs more readily at high latitudes, with such nascent species especially prone to extinction by fusion, we derive the ephemeral ecological speciation hypothesis as an integrative mechanistic explanation for latitudinal gradients in species turnover and the net accumulation of biodiversity.

  20. Speciation of arsenic and mercury in feed: why and how?

    DEFF Research Database (Denmark)

    Hedegaard, Rikke Susanne Vingborg; Sloth, Jens Jørgen

    2011-01-01

    The understanding of the mechanisms of biological activities and biotransformation of trace elements such as arsenic and mercury has improved during recent years with the help of chemical speciation studies. However, the most important practical application of elemental speciation is in the area...... of toxicology. Toxicological knowledge on the individual trace element species can lead to more specific legislation of hazardous substances found in feed. Examples here are arsenic, where the inorganic forms are the most toxic, and mercury, where the organic form methylmercury is more toxic than inorganic...... mercury. In the present paper an overview of the current knowledge on arsenic and mercury speciation in feed and analytical methodologies for arsenic and mercury speciation analysis are given. Additionally the current status and expected future developments within legislation for trace element speciation...

  1. Chemical Speciation Analysis and Environmental Behaviour of 127I and 129I

    DEFF Research Database (Denmark)

    Hansen, Violeta

    2011-01-01

    be used as a bio-indicator for iodine-129 in the marine environment. The results shows however that iodide is somewhat more efficient accumulate than iodate in Fucus. A rapid on-line HPLC-ICP-MS method for direct speciation analysis of 127I (as iodide and iodate) in water samples was developed. The method...

  2. Bulk Glassy Alloys: Historical Development and Current Research

    Directory of Open Access Journals (Sweden)

    Akihisa Inoue

    2015-06-01

    Full Text Available This paper reviews the development of current research in bulk glassy alloys by focusing on the trigger point for the synthesis of the first bulk glassy alloys by the conventional mold casting method. This review covers the background, discovery, characteristics, and applications of bulk glassy alloys, as well as recent topics regarding them. Applications of bulk glassy alloys have been expanding, particularly for Fe-based bulk glassy alloys, due to their unique properties, high glass-forming ability, and low cost. In the near future, the engineering importance of bulk glassy alloys is expected to increase steadily, and continuous interest in these novel metallic materials for basic science research is anticipated.

  3. The rate test of speciation: estimating the likelihood of non-allopatric speciation from reproductive isolation rates in Drosophila.

    Science.gov (United States)

    Yukilevich, Roman

    2014-04-01

    Among the most debated subjects in speciation is the question of its mode. Although allopatric (geographical) speciation is assumed the null model, the importance of parapatric and sympatric speciation is extremely difficult to assess and remains controversial. Here I develop a novel approach to distinguish these modes of speciation by studying the evolution of reproductive isolation (RI) among taxa. I focus on the Drosophila genus, for which measures of RI are known. First, I incorporate RI into age-range correlations. Plots show that almost all cases of weak RI are between allopatric taxa whereas sympatric taxa have strong RI. This either implies that most reproductive isolation (RI) was initiated in allopatry or that RI evolves too rapidly in sympatry to be captured at incipient stages. To distinguish between these explanations, I develop a new "rate test of speciation" that estimates the likelihood of non-allopatric speciation given the distribution of RI rates in allopatry versus sympatry. Most sympatric taxa were found to have likely initiated RI in allopatry. However, two putative candidate species pairs for non-allopatric speciation were identified (5% of known Drosophila). In total, this study shows how using RI measures can greatly inform us about the geographical mode of speciation in nature.

  4. Arsenic speciation patterns in freshwater fish.

    Science.gov (United States)

    Slejkovec, Zdenka; Bajc, Zlatka; Doganoc, Darinka Z

    2004-04-19

    Muscle of 16 freshwater fish (9 different species belonging to 4 different families) was analysed for arsenic species using HPLC separation (anion and cation exchange) followed by on-line UV-decomposition, hydride generation and AFS detection. The main arsenic compounds found in the extracts were arsenobetaine (AsB), which accounted for 92-100% of extractable arsenic in species of salmonids (Salmo marmoratus, Oncorhynchus mykiss, Salmo trutta m. fario), and dimethylarsinic acid (DMAA), which accounted for 75% of extractable arsenic in burbot (Lota lota). AsB was also found in lower concentrations in almost all other fish species analysed (Silurus glanis, L. lota, Barbus barbus, Rutilus pigus virgo, Chondrostoma nasus). Arsenite (As(III)) and trimethylarsine oxide (TMAO) were detected in low concentrations in some representatives of Cyprinidae only (R. pigus virgo, C. nasus). Except in salmonids, an unknown cationic compound was present in most of the samples in relatively low concentrations. Cluster analysis of the generated data seems to indicate that there is a correlation between fish family and the arsenic speciation pattern. This is especially clear for the salmonids which show a completely separate cluster and thus a very distinct arsenic speciation pattern.

  5. Chemical speciation code CHEMSPEC and its applications

    Institute of Scientific and Technical Information of China (English)

    WANG XiangYun; CHEN Tao; LIU ChunLi

    2009-01-01

    The adsorption and migration behavior of a radionuclide in geological media heavily depends on its chemical forms in a given chemical environment.In order to predict the temporal and spatial distribution of radionuclides around a disposal site when its canister is damaged,it is necessary to develop coupled chemical speciation-solute transport models and relevant software.For that reason,we wrote a new chemical speciation program CHEMSPEC.In this paper,the principles and structure of CHEMSPEC are briefly described,and the strategy and algorithms that were used in this code are interpreted in some detail,such as the measures adopted to prevent divergence in iteratively solving the mass balance equations,the "predictor-corrector" algorithm for calculation of the number and quantities of solid species formed,and the alternate use of "freezing" and "defreezing" oxidation states in handling of co-existent redox and precipitation equilibria.Four examples are given to illustrate CHEMSPEC's features and capabilities.

  6. Chemical speciation code CHEMSPEC and its applications

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The adsorption and migration behavior of a radionuclide in geological media heavily depends on its chemical forms in a given chemical environment.In order to predict the temporal and spatial distribution of radionuclides around a disposal site when its canister is damaged,it is necessary to develop coupled chemical speciation-solute transport models and relevant software.For that reason,we wrote a new chemical speciation program CHEMSPEC.In this paper,the principles and structure of CHEMSPEC are briefly described,and the strategy and algorithms that were used in this code are interpreted in some detail,such as the measures adopted to prevent divergence in iteratively solving the mass balance equations,the "predictor-corrector" algorithm for calculation of the number and quantities of solid species formed,and the alternate use of "freezing" and "defreezing" oxidation states in handling of co-existent redox and precipitation equilibria.Four examples are given to illustrate CHEMSPEC’s features and capabilities.

  7. Mercury speciation by CE: an update.

    Science.gov (United States)

    Kubán, Petr; Pelcová, Pavlína; Margetínová, Jana; Kubán, Vlastimil

    2009-01-01

    This review provides an update on mercury speciation by CE. It includes a brief discussion on physicochemical properties, toxicity and transformation pathways of mercury species (i.e. methyl-, ethyl-, phenyl- and inorganic mercury) and outlines recent trends in Hg speciation by CE. CE is presented as a complementary technique to chromatographic separation techniques, especially in cases when speed, high efficiency and low sample volumes are required. The development of suitable sample preconcentration/isolation (sample stacking, ion exchange, liquid-liquid-liquid extraction, dual-cloud point extraction) to achieve low LODs for analysis of trace concentrations of mercury species in real samples is emphasized. Hyphenation of CE to element specific detectors (i.e. electrothermal atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry) is discussed as well as a potential of CE in interaction studies that may provide useful information on interaction of various Hg species with selected bio-macromolecules.

  8. Determination of mercury speciation in fish tissue with a direct mercury analyzer.

    Science.gov (United States)

    Barst, Benjamin D; Hammerschmidt, Chad R; Chumchal, Matthew M; Muir, Derek C G; Smith, James D; Roberts, Aaron P; Rainwater, Thomas R; Drevnick, Paul E

    2013-06-01

    Knowledge of Hg speciation in tissue is valuable for assessing potential toxicological effects in fish. Direct Hg analyzers, which use thermal decomposition and atomic absorption spectrometry, have recently gained popularity for determining organic Hg after procedural solvent extraction from some environmental media, although quantitative recovery from lipid-rich materials, such as fish liver, has been problematic. The authors developed a new method by which organic Hg in fish liver and muscle is estimated by the difference between direct measurements of inorganic Hg in an acid extract and total Hg in whole tissue. The method was validated by analysis of a certified reference material (DOLT-4 dogfish liver) and naturally contaminated fish tissues with comparison to an established Hg speciation method (gas chromatography cold vapor atomic fluorescence spectrometry). Recovery of organic Hg from DOLT-4, estimated by difference, averaged 99 ± 5% of the mean certified value for methylmercury. In most liver samples and all muscle samples, estimates of organic Hg from the proposed method were indiscernible from direct speciation measurements of methylmercury (99% ± 6%). Estimation of organic Hg by the difference between total Hg and inorganic Hg was less accurate in liver samples with a high percentage of inorganic Hg (90%). This was because of the increased uncertainty that results from estimating a third value (i.e., organic Hg) by using the difference between two large concentrations (inorganic and total Hg). The proposed method is a useful tool for examining the speciation of Hg in fish muscle and liver, and by extension, potentially other tissues and environmental media.

  9. Can bulk viscosity drive inflation

    Energy Technology Data Exchange (ETDEWEB)

    Pacher, T.; Stein-Schabes, J.A.; Turner, M.S.

    1987-04-01

    Contrary to other claims, we argue that, bulk viscosity associated with the interactions of nonrelativistic particles with relativistic particles around the time of the grand unified theory (GUT) phase transition cannot lead to inflation. Simply put, the key ingredient for inflation, negative pressure, cannot arise due to the bulk viscosity effects of a weakly-interacting mixture of relativistic and nonrelativistic particles. 13 refs., 1 fig.

  10. Arsenic speciation by hydride generation-quartz furnace atomic absorption spectrometry. Optimization of analytical parameters and application to environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Molenat, N.; Astruc, A.; Holeman, M.; Pinel, R. [Laboratoire de Chimie Analytique Bioinorganique et Environnement, Dept. de Chimie, Faculte des Sciences et Techniques, 64 - Pau (France); Maury, G. [Montpellier-2 Univ., 34 (France). Dept. de Chimie Organique Fine

    1999-11-01

    Analytical parameters of hydride generation, trapping, gas chromatography and atomic absorption spectrometry detection in a quartz cell furnace (HG/GC/QFAAS) device have been optimized in order to develop an efficient and sensitive method for arsenic compounds speciation. Good performances were obtained with absolute detection limits in the range of 0.1 - 0.5 ng for arsenite, arsenate, mono-methyl-arsonic acid (MMAA), dimethyl-arsinic acid (DMAA) and trimethyl-arsine oxide (TMAO). A pH selective reduction for inorganic arsenic speciation was successfully reported. Application to the accurate determination of arsenic compounds in different environmental samples was performed. (authors)

  11. A review on speciation of iodine-129 in the environmental and biological samples

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Hansen, Violeta; Aldahan, Ala

    2009-01-01

    plants, the I-129/I-127 ratios have being reached to values of 10(-10) to 10(-4) in the environment from 10(-12) in the pre-nuclear era. In this article, we review the occurrence, sources, inventory, and concentration level of I-129 in environment and the method for speciation analysis of I-129...... toxicity (close to thyroid) of I-129 are discussed. (C) 2008 Elsevier B.V. All rights reserved....

  12. Genomic islands of speciation in Anopheles gambiae.

    Directory of Open Access Journals (Sweden)

    2005-09-01

    Full Text Available The African malaria mosquito, Anopheles gambiae sensu stricto (A. gambiae, provides a unique opportunity to study the evolution of reproductive isolation because it is divided into two sympatric, partially isolated subtaxa known as M form and S form. With the annotated genome of this species now available, high-throughput techniques can be applied to locate and characterize the genomic regions contributing to reproductive isolation. In order to quantify patterns of differentiation within A. gambiae, we hybridized population samples of genomic DNA from each form to Affymetrix GeneChip microarrays. We found that three regions, together encompassing less than 2.8 Mb, are the only locations where the M and S forms are significantly differentiated. Two of these regions are adjacent to centromeres, on Chromosomes 2L and X, and contain 50 and 12 predicted genes, respectively. Sequenced loci in these regions contain fixed differences between forms and no shared polymorphisms, while no fixed differences were found at nearby control loci. The third region, on Chromosome 2R, contains only five predicted genes; fixed differences in this region were also verified by direct sequencing. These "speciation islands" remain differentiated despite considerable gene flow, and are therefore expected to contain the genes responsible for reproductive isolation. Much effort has recently been applied to locating the genes and genetic changes responsible for reproductive isolation between species. Though much can be inferred about speciation by studying taxa that have diverged for millions of years, studying differentiation between taxa that are in the early stages of isolation will lead to a clearer view of the number and size of regions involved in the genetics of speciation. Despite appreciable levels of gene flow between the M and S forms of A. gambiae, we were able to isolate three small regions of differentiation where genes responsible for ecological and behavioral

  13. Lead Speciation in remote Mountain Lakes

    Science.gov (United States)

    Plöger, A.; van den Berg, C. M. G.

    2003-04-01

    In natural waters trace metals can become complexed by organic matter. This complexation can change the geochemistry of the metals by preventing them being scavenged, thereby increasing their residence time in the water column. The chemical speciation of trace metals also affects the bioavalability and their toxicological impact on organisms. It is therefore important to determine the chemical speciation of trace metals as well as their concentrations. Mountain lakes have been less studied in the past than other lakes- partly because of their remoteness and partly because they were perceived to be unpolluted and undisturbed. But work so far on mountain lakes has shown that most sites are affected and threatened, for example by transboundary air pollutants like trace metals. One of the important features that distinguishes these lakes from lowland lakes at similar latitudes is the fact that they may be isolated from the atmosphere for six months or more during the winter by a thick ice cover. Also, as these lakes are remote from direct anthropogenic influences, they reflect the regional distribution of pollutants transferred via the atmosphere. For this work, under the framework of the EMERGE (European Mountain lake Ecosystems: Regionalisation, diaGnostic and socio-economic Evaluation) programme, two remote mountain lakes have been studied in detail, with water sampling taking place at different times of the year to investigate possible seasonal differences in lead concentrations and speciation. Results so far have shown that lead-complexing ligand concentrations are in excess to dissolved lead concentrations, indicating that dissolved lead probably occurs fully complexed in these lakes. Therefore the toxic fraction is likely to be less than the dissolved lead concentration. Also, lead concentrations at the time of the spring thaw are higher than autumn concentrations just before ice cover, indicating that a significant proportion of fallout onto the lake catchment

  14. Bulk density - RTD results and status of the standardisation

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, T.; Hartmann, H. [Technologie- und Foerderzentrum fuer Nachwachsende Rohstoffe - TFZ, Straubing (Germany); Daugbjerg Jensen, P. [Royal Veterinary and Agricultural University, Vejle (Denmark). Danish Centre for Forest, Landscape and Planning - DFLRI; Temmerman, M.; Rabier, F. [CRA, Gembloux (Belgium). Department Genie Rural; Jirjis, R.; Burvall, J. [Swedish University of Agricultural Sciences, Uppsala (Sweden). Department of Bioenergy; Hersener, J.L. [Ingenieurbuero HERSENER, Wiesendangen (Switzerland); Rathbauer, J. [Bundesanstalt fuer Landtechnik - BLT, Wieselburg (Austria)

    2004-07-01

    Bulk density is an important property for determining storage and transportation room demands and for volume based payment of biofuels. It is also used for calculation of the energy density. Furthermore, bulk density influences the readings from many physical principles for rapid moisture content determination (e. g. microwave reflection method, time domain reflectometric or capacitive sensors [6]). Although bulk density is mostly regarded as an easily determinable parameter, the applied national and international standard methods are highly inconsistent in practice [1, 4, 8]. The goal of the here presented research was therefore to provide a sound knowledge basis for bulk density determination, which shall be used in the ongoing process of European biofuel standardisation. In particular the research focus was to determine the - effect of container size and shape in respect of different biofuels, - effect of shock impact and the - effect of moisture content (as received) on measured bulk density (dry basis). (orig.)

  15. Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

    Directory of Open Access Journals (Sweden)

    Rajmund Michalski

    2012-01-01

    Full Text Available Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices.

  16. The Interplay of Al and Mg Speciation in Advanced Mg Battery Electrolyte Solutions.

    Science.gov (United States)

    See, Kimberly A; Chapman, Karena W; Zhu, Lingyang; Wiaderek, Kamila M; Borkiewicz, Olaf J; Barile, Christopher J; Chupas, Peter J; Gewirth, Andrew A

    2016-01-13

    Mg batteries are an attractive alternative to Li-based energy storage due to the possibility of higher volumetric capacities with the added advantage of using sustainable materials. A promising emerging electrolyte for Mg batteries is the magnesium aluminum chloride complex (MACC) which shows high Mg electrodeposition and stripping efficiencies and relatively high anodic stabilities. As prepared, MACC is inactive with respect to Mg deposition; however, efficient Mg electrodeposition can be achieved following an electrolytic conditioning process. Through the use of Raman spectroscopy, surface enhanced Raman spectroscopy, (27)Al and (35)Cl nuclear magnetic resonance spectroscopy, and pair distribution function analysis, we explore the active vs inactive complexes in the MACC electrolyte and demonstrate the codependence of Al and Mg speciation. These techniques report on significant changes occurring in the bulk speciation of the conditioned electrolyte relative to the as-prepared solution. Analysis shows that the active Mg complex in conditioned MACC is very likely the [Mg2(μ-Cl)3·6THF](+) complex that is observed in the solid state structure. Additionally, conditioning creates free Cl(-) in the electrolyte solution, and we suggest the free Cl(-) adsorbs at the electrode surface to enhance Mg electrodeposition.

  17. Contribution of analytical techniques coupled to the knowledge of the uranium speciation in natural conditions; Apports des techniques analytiques couplees a la connaissance de la speciation de l'uranium en conditions naturelles

    Energy Technology Data Exchange (ETDEWEB)

    Petit, J.

    2009-06-15

    To understand the transport mechanisms and the radionuclides behaviour in the bio-geosphere is necessary to evaluate healthy and environmental risks of nuclear industry. These mechanisms are monitored by radioelements speciation, namely the distribution between their different physico-chemical forms in the environment. From this perspective, this PhD thesis deals with uranium speciation in a natural background. A detailed summary of uranium biogeochemistry has been written, which enables to restrict the PhD issue to uranium complexation with oxalic acid, a hydrophilic organic acid with good binding properties, ubiquitous in soil waters. Analytical conditions have been established by means of speciation diagrams. The speciation diagrams building by means of literature stability constants has allowed to define the analytical conditions of complex formation. The chosen analytical technique is the hyphenation of a separative technique (liquid chromatography LC or capillary electrophoresis CE) with mass spectrometry (ICPMS). The studied complexes presence in the synthetic samples has been confirmed with UV/visible spectrophotometry. LC-ICPMS analyses have proved the lability of the uranyl-organic acid complexes, namely their tendency to dissociate during analysis, which prevents from studying uranium speciation. CE-ICPMS study of labile complexes from a metal-ligand system has been made possible by employing affinity capillary electrophoresis, which enables to determine stability constants and electrophoretic mobilities. This PhD thesis has allowed to compare the different mathematical treatments of binding isotherm and to take into account ionic strength and real ligand concentration. Affinity CE has been applied successfully to lanthanum-oxalate (model system) and uranium-oxalate systems. The obtained results have been applied to a real system (situated in Le Bouchet). This shows the contribution of the developed method to the modelling of uranium speciation. (author)

  18. Integration of bulk piezoelectric materials into microsystems

    Science.gov (United States)

    Aktakka, Ethem Erkan

    Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with management IC, which incorporates a supply-independent bias circuitry, an active diode for low-dropout rectification, a bias-flip system for higher efficiency, and a trickle battery charger. The overall system does not require a pre-charged battery, and has power consumption of sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.

  19. Spatially Resolved Sulfur Speciation in Urban Soils

    Science.gov (United States)

    Brettholle, M.; Gleber, S.-C.; Mekiffer, B.; Legnini, D.; McNulty, I.; Vogt, S.; Wessolek, G.; Thieme, J.

    2011-09-01

    A combination of x-ray microscopy, elemental mapping, and XANES spectroscopy at the K-absorption edge of sulfur was used to analyze the elemental and particulate composition of an urban soil loaded with building rubble from WWII, exemplarily from Berlin, Germany. This combination of element specific high-resolution microscopy with high spectral resolution capabilities allows for the determination of elemental composition as well as chemical speciation and is therefore well suited for the analysis of highly heterogeneous environmental samples. Different soil and debris constituents could be assigned to elemental distribution patterns within collected fluorescence maps, allowing for a detailed analysis of the sulfur pool and release from war debris in subsequent studies. A detailed understanding of this sulfur lixiviation is central to preserve urban water quality.

  20. Speciation of arsenic in sulfidic waters

    Directory of Open Access Journals (Sweden)

    Ford Robert G

    2003-03-01

    Full Text Available Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH2S from 10-7.5 to 10-3.0 M, ΣAs from 10-5.6 to 10-4.8 M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH30, and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10-4.3 M at neutral pH. Conversion from neutral As(OH30 to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions.

  1. Chemical state speciation by resonant Raman scattering

    CERN Document Server

    Karydas, A G; Zarkadas, C; Paradelis, T; Kallithrakas-Kontos, N

    2002-01-01

    In the resonant Raman scattering (RRS) process the emitted photon exhibits a continuous energy distribution with a high energy cutoff limit. This cutoff energy depends on the chemical state of the element under examination. In the present work, the possibility of identifying the chemical state of V atoms by employing RRS spectroscopy with a semiconductor Si(Li) detector is investigated. A proton induced Cr K alpha x-ray beam was used as the incident radiation, having a fixed energy lower than the V K-absorption edge. The net RRS distributions extracted from the energy dispersive spectra of metallic V and its compound targets were simulated by an appropriate theoretical model. The results showed the possibility of employing RRS spectroscopy with a semiconductor detector for chemical speciation studies.

  2. Horizontal Gene Transfer, Dispersal and Haloarchaeal Speciation

    Directory of Open Access Journals (Sweden)

    R. Thane Papke

    2015-05-01

    Full Text Available The Halobacteria are a well-studied archaeal class and numerous investigations are showing how their diversity is distributed amongst genomes and geographic locations. Evidence indicates that recombination between species continuously facilitates the arrival of new genes, and within species, it is frequent enough to spread acquired genes amongst all individuals in the population. To create permanent independent diversity and generate new species, barriers to recombination are probably required. The data support an interpretation that rates of evolution (e.g., horizontal gene transfer and mutation are faster at creating geographically localized variation than dispersal and invasion are at homogenizing genetic differences between locations. Therefore, we suggest that recurrent episodes of dispersal followed by variable periods of endemism break the homogenizing forces of intrapopulation recombination and that this process might be the principal stimulus leading to divergence and speciation in Halobacteria.

  3. Horizontal Gene Transfer, Dispersal and Haloarchaeal Speciation

    Science.gov (United States)

    Papke, R. Thane; Corral, Paulina; Ram-Mohan, Nikhil; de la Haba, Rafael R.; Sánchez-Porro, Cristina; Makkay, Andrea; Ventosa, Antonio

    2015-01-01

    The Halobacteria are a well-studied archaeal class and numerous investigations are showing how their diversity is distributed amongst genomes and geographic locations. Evidence indicates that recombination between species continuously facilitates the arrival of new genes, and within species, it is frequent enough to spread acquired genes amongst all individuals in the population. To create permanent independent diversity and generate new species, barriers to recombination are probably required. The data support an interpretation that rates of evolution (e.g., horizontal gene transfer and mutation) are faster at creating geographically localized variation than dispersal and invasion are at homogenizing genetic differences between locations. Therefore, we suggest that recurrent episodes of dispersal followed by variable periods of endemism break the homogenizing forces of intrapopulation recombination and that this process might be the principal stimulus leading to divergence and speciation in Halobacteria. PMID:25997110

  4. Nitrogen speciation in mantle and crustal fluids

    Science.gov (United States)

    Li, Yuan; Keppler, Hans

    2014-03-01

    Seventy-nine experiments have been carried out at 600-1400 °C, 2-35 kbar, and oxygen fugacities ranging from the Fe-FeO to the Re-ReO2 buffer to investigate the nitrogen speciation in mantle and crustal N-H-O fluids. Laser Raman analyses of fluid inclusions trapped in situ in quartz and olivine crystals show that N2 and/or NH3 are the only detectable nitrogen species in the fluids at the conditions of the present study. The results further show that in the fluids of the oxidized shallow upper mantle, nitrogen is mostly present as N2, while in the deep reduced upper mantle, NH3 is the dominant nitrogen species. Nitrogen speciation in subduction zone fluids is also calculated from the experimental data to constrain the efficiency of nitrogen recycling. The data show that a hot, oxidized slab is an efficient barrier for deep nitrogen subduction, while a cold, reduced slab would favor recycling nitrogen into the deep mantle. The nitrogen species in magmatic fluids of mid-ocean ridge basalt and arc magmas are predominantly N2, but a significant fraction of nitrogen can be NH3 at certain conditions. The nitrogen species in fluids released from the solidifying magma ocean and the reduced young mantle may have been mostly NH3. The release of such fluids may have created a reduced atmosphere on the every early Earth, with an elevated concentration of NH3. This may not only resolve the faint young Sun paradox but may also have created favorable conditions for the formation of biomolecules through Miller-Urey type reactions.

  5. Speciation of metals in natural waters

    Directory of Open Access Journals (Sweden)

    Millero Frank

    2001-09-01

    Full Text Available The form or speciation of a metal in natural waters can change its kinetic and thermodynamic properties. For example, Cu(II in the free ionic form is toxic to phytoplankton, while copper complexed to organic ligands is not toxic. The form of a metal in solution can also change its solubility. For example, Fe(II is soluble in aqueous solutions while Fe(III is nearly insoluble. Natural organic ligands interactions with Fe(III can increase the solubility by 20-fold in seawater. Ionic interaction models that can be used to determine the activity and speciation of divalent and trivalent metals in seawater and other natural elements will be discussed. The model is able to consider the interactions of metals with the major (Cl-, SO42-, HCO3-, CO32-, Br-, F- and minor (OH-, H2PO4-, HPO42-, PO43-, HS- anions as a function of temperature (0 to 50 °C, ionic strength [0 to 6 m (m = mol kg-1] and pH (1 to 13. Recently, it has been shown that many divalent metals are complexed with organic ligands. Although the composition of these ligands is not known, a number of workers have used voltammetry to determine the concentration of the ligand [Ln] and the stability constant (KML for the formation of the complex M2+ + Ln → MLn+2 KML= [MLn+2]/[M2+] [Ln] We have added the experimental values of KML for the formation of complexes of natural organics in seawater of known concentration ([Ln] with Cu2+, Zn2+, Cd2+, Co2+, and Fe3+ . The model can be used to examine the competition of inorganic and organic ligands for divalent metals as a function of ionic strength. The importance of organic ligands in controlling the solubility of Fe(III in seawater will be discussed. New experimental studies are needed to extend the model to higher temperatures and ionic strength.

  6. Selenium speciation analysis of Misgurnus anguillicaudatus selenoprotein by HPLC-ICP-MS and HPLC-ESI-MS/MS

    Science.gov (United States)

    Analytical methods for selenium (Se) speciation were developed using high performance liquid chromatography (HPLC) coupled to either inductively coupled plasma mass spectrometry (ICP-MS) or electrospray ionization tandem mass spectrometry (ESI-MS/MS). Separations of selenomethionine (Se-Met) and sel...

  7. 密集烤房不同装烟方式对比试验研究%Comparative Test for Different Methods of Loading Tobacco Leaves in Bulk Curing Barn

    Institute of Scientific and Technical Information of China (English)

    叶志国; 杨占伟; 陈献勇; 王鹏; 郑仕发

    2013-01-01

    为了选出减工增效的装烟方式,对3种不同的装烟方式进行了对比试验.结果表明:与常规的绑竿装烟方式相比,采用散叶、烟夹装烟方式,烤房装烟容量分别增加了57.89%和18.42%,装烤效率分别提高了63.53%、49.02%,卸烤效率分别提高了77.66%、39.30%,烘烤每千克干烟分别节省了能耗成本0.70、0.28元,烘干100 kg鲜烟叶的用时分别减少了0.83、0.27 h;采用烟夹装烟方式的烤后烟的上等烟比例高,散叶方式烤后烟的外观质量较好.%In order to reduce the labor cost and increase the benefit, we compared three different methods of loading tobacco leaves in bulk curing bam. Compared with the traditional leaf - loading method with pole, using loose - leaf method and tobacco -clip method increased bam loading capacity by 57. 89% and 18.42% , respectively, enhanced loading efficiency by 63. 53% and 49.02% , respectively, improved unloading efficiency by 77.66% and 39.30% , separately, saved the energy consumption cost of roasting 1 kg dry tobacco leaf by 0.70 and 0.28 yuan, respectively, and reduced the time for drying 100 kg fresh tobacco leaf by 0.83 and 0.27 h separately. The proportion of high - class tobacco leaf roasted with tobacco - clip leaf - loading method was higher, and the appearance quality of tobacco leaf roasted with the loose - leaf method was better.

  8. Genetic structure and bio-climatic modeling support allopatric over parapatric speciation along a latitudinal gradient

    Directory of Open Access Journals (Sweden)

    Rossetto Maurizio

    2012-08-01

    Full Text Available Abstract Background Four of the five species of Telopea (Proteaceae are distributed in a latitudinal replacement pattern on the south-eastern Australian mainland. In similar circumstances, a simple allopatric speciation model that identifies the origins of genetic isolation within temporal geographic separation is considered as the default model. However, secondary contact between differentiated lineages can result in similar distributional patterns to those arising from a process of parapatric speciation (where gene flow between lineages remains uninterrupted during differentiation. Our aim was to use the characteristic distributional patterns in Telopea to test whether it reflected the evolutionary models of allopatric or parapatric speciation. Using a combination of genetic evidence and environmental niche modelling, we focused on three main questions: do currently described geographic borders coincide with genetic and environmental boundaries; are there hybrid zones in areas of secondary contact between closely related species; did species distributions contract during the last glacial maximum resulting in distributional gaps even where overlap and hybridisation currently occur? Results Total genomic DNA was extracted from 619 individuals sampled from 36 populations representing the four species. Seven nuclear microsatellites (nSSR and six chloroplast microsatellites (cpSSR were amplified across all populations. Genetic structure and the signature of admixture in overlap zones was described using the Bayesian clustering methods implemented in STUCTURE and NewHybrids respectively. Relationships between chlorotypes were reconstructed as a median-joining network. Environmental niche models were produced for all species using environmental parameters from both the present day and the last glacial maximum (LGM. The nSSR loci amplified a total of 154 alleles, while data for the cpSSR loci produced a network of six chlorotypes. STRUCTURE revealed

  9. Phylogenetic estimates of speciation and extinction rates for testing ecological and evolutionary hypotheses.

    Science.gov (United States)

    Pyron, R Alexander; Burbrink, Frank T

    2013-12-01

    Phylogenies are used to estimate rates of speciation and extinction, reconstruct historical diversification scenarios, and link these to ecological and evolutionary factors, such as climate or organismal traits. Recent models can now estimate the effects of binary, multistate, continuous, and biogeographic characters on diversification rates. Others test for diversity dependence (DD) in speciation and extinction, which has become recognized as an important process in numerous clades. A third class incorporates flexible time-dependent functions, enabling reconstruction of major periods of both expanding and contracting diversity. Although there are some potential problems (particularly for estimating extinction), these methods hold promise for answering many classic questions in ecology and evolution, such as the origin of adaptive radiations, and the latitudinal gradient in species richness.

  10. Multiply associating electrolytes in the binding mean spherical approximation: Thermodynamic properties and speciation

    Science.gov (United States)

    Bernard, O.; Torres-Arenas, J.; Simonin, J.-P.

    2014-01-01

    Ionic solutions exhibiting multiple association are described within the binding mean spherical approximation (BiMSA). This model is based on the Wertheim formalism, in the framework of the primitive model at the McMillan-Mayer level. The cation and the anion form the various complexes according to stepwise complexation-equilibria. Analytic expressions for the Helmholtz energy, the internal energy, the speciation, and for the osmotic and activity coefficients are given considering a binary solution with an arbitrary number of association sites on one type of ion (polyion) and one site on the ions of opposite sign (counterions). As an alternative, mean field expressions, as developed in SAFT-type theories, are also presented. The result obtained from the latter approximate method exhibits a reasonable agreement with those from BiMSA for the speciation, and a remarkable one for the osmotic coefficient.

  11. Multiply associating electrolytes in the binding mean spherical approximation: Thermodynamic properties and speciation

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, O., E-mail: olivier.bernard@upmc.fr; Simonin, J.-P. [Laboratoire Physicochimie des Electrolytes, Colloïdes et Sciences Analytiques, PECSA (UMR CNRS 7195), Université P. M. Curie, Case 51, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Torres-Arenas, J. [División de Ciencias e Ingenierías, Universidad de Guanajuato, Loma del Bosque 103, Colonia Lomas del Campestre, León, Guanajuato, CP 37150 (Mexico)

    2014-01-21

    Ionic solutions exhibiting multiple association are described within the binding mean spherical approximation (BiMSA). This model is based on the Wertheim formalism, in the framework of the primitive model at the McMillan-Mayer level. The cation and the anion form the various complexes according to stepwise complexation-equilibria. Analytic expressions for the Helmholtz energy, the internal energy, the speciation, and for the osmotic and activity coefficients are given considering a binary solution with an arbitrary number of association sites on one type of ion (polyion) and one site on the ions of opposite sign (counterions). As an alternative, mean field expressions, as developed in SAFT-type theories, are also presented. The result obtained from the latter approximate method exhibits a reasonable agreement with those from BiMSA for the speciation, and a remarkable one for the osmotic coefficient.

  12. Multiply associating electrolytes in the binding mean spherical approximation: thermodynamic properties and speciation.

    Science.gov (United States)

    Bernard, O; Torres-Arenas, J; Simonin, J-P

    2014-01-21

    Ionic solutions exhibiting multiple association are described within the binding mean spherical approximation (BiMSA). This model is based on the Wertheim formalism, in the framework of the primitive model at the McMillan-Mayer level. The cation and the anion form the various complexes according to stepwise complexation-equilibria. Analytic expressions for the Helmholtz energy, the internal energy, the speciation, and for the osmotic and activity coefficients are given considering a binary solution with an arbitrary number of association sites on one type of ion (polyion) and one site on the ions of opposite sign (counterions). As an alternative, mean field expressions, as developed in SAFT-type theories, are also presented. The result obtained from the latter approximate method exhibits a reasonable agreement with those from BiMSA for the speciation, and a remarkable one for the osmotic coefficient.

  13. 阿加曲班原料药中催化剂钯残留监测方法建立%Establishment of a Method for Monitoring the Catalyst Palladium Residual Content in Argatroban Bulk Drug

    Institute of Scientific and Technical Information of China (English)

    郭旭光; 郑子栋; 郭毅

    2014-01-01

    目的:建立凝血酶抑制剂阿加曲班原料药中催化剂钯的残留量测定方法。方法采用石墨炉原子吸收分光光度法测定阿加曲班中钯的残留量。试验条件:光源为钯空心阴极灯,波长247.6 nm,狭缝0.5 nm,灯电流10 mA,燃烧器高度2 mm,石墨管以横向加热方式,氩气压力0.4 MPa,进样体积20μL,背景校正D2,石墨炉程序升温。结果钯在0.015~0.2μg·mL-1范围内与吸光度呈良好的线性关系(r=0.9996);检出限为0.00057μg·mL-1;特征浓度为0.00107μg·mL-1;平均回收率为99.8%;RSD 为4.08%(n=9)。结论该方法经方法学验证可用于阿加曲班原料药中痕量钯含量的测定,可为该原料药质量标准的完善提供参考。%Objective To establish a method for the content determination of palladium catalyst residue in thrombin inhibitor argatroban bulk drug.Methods Graphite furnace atomic absorption spectrometry (AAS)method was used to determine palladium residue content in argatroban.Test conditions were as follows.The palladium hollow cathode lamp was used for light source.The detection wavelength was 247.6 nm,and the slit was 0.5 nm.The lamp current was 10 mA,and the burner height was 2 mm with transverse heating graphite tube.The argon pressure was 0.4 MPa.The injection volume was 20μL with background correction D2.The temperature program was used for graphite furnace.Results It showed a good linear relationship within the concentration range of 0.0 1 5-0.2 μg · mL-1 (r=0.9 9 9 6 ). The detection limit and the characteristic concentration were 0.00057 μg · mL-1 and 0.00107 μg · mL-1 , respectively.The average recovery was 99.8%,with RSD of 4.08% (n=9).Conclusion This method could be used for the determination of the trace palladium content in argatroban bulk drug after methodology verification,and could provide reference for improving quality standard of the raw material medicine.

  14. Speciation Analysis of Serum Copper by Ultrafiltration Com-bined with Graphite Furnace Atomic Absorption Spectrometry

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Hua; MA Hui-Min; MA Quan-Li; LIANG Shu-Chuan

    2001-01-01

    UItrafiltration combined with graphite furnace atomic absorp-tion spectrometry(GFAAS)was used to study protein binding and speciation of copper in human serum..UItrafiltration was carried out using a cell unit ultrafiltration membraoes having a nominal cut-off of 10,000Dalton.The effects of var-ious experimental factors including the kind and concentration of electrolyte,sample storge,pH,pressure and the precon-ditioning of the membranes on the speciation analysis of serum copper by ultrafiltration were examined.It was observed that 4.5±2.3% of the total copper in serum was ultrafiltrable and this value did not seem to be influenced by the total serum ele-mental concentration,the PH (6.5——10) adn the pressure(≤1.5kg/cm2).the preconditioning of the ultrafiltration system with 0.1mol/L calcium nitrate can overcome the adsorption loss of copper effectively,and the addition of tris-HCI sohtion (pH 7.4)to serum accelerates the ultrafiltration.The present method was proved to be suitable for speciation analysis for its simplicity,rapidity,small sample reuqirement and easy con-trol.The results obtained with the method are accurate and reliable.

  15. Pb Speciation Data to Estimate Lead Bioavailability to Quail

    Data.gov (United States)

    U.S. Environmental Protection Agency — Linear combination fitting data for lead speciation of soil samples evaluated through an in-vivo/in-vitro correlation for quail exposure. This dataset is associated...

  16. A dynamical theory of speciation on holey adaptive landscapes

    CERN Document Server

    Gavrilets, S

    1998-01-01

    The metaphor of holey adaptive landscapes provides a pictorial representation of the process of speciation as a consequence of genetic divergence. In this metaphor, biological populations diverge along connected clusters of well-fit genotypes in a multidimensional adaptive landscape and become reproductively isolated species when they come to be on opposite sides of a ``hole'' in the adaptive landscape. No crossing of any adaptive valleys is required. I formulate and study a series of simple models describing the dynamics of speciation on holey adaptive landscapes driven by mutation and random genetic drift. Unlike most previous models that concentrate only on some stages of speciation, the models studied here describe the complete process of speciation from initiation until completion. The evolutionary factors included are selection (reproductive isolation), random genetic drift, mutation, recombination, and migration. In these models, pre- and post-mating reproductive isolation is a consequence of cumulativ...

  17. Male competition fitness landscapes predict both forward and reverse speciation.

    Science.gov (United States)

    Keagy, Jason; Lettieri, Liliana; Boughman, Janette W

    2016-01-01

    Speciation is facilitated when selection generates a rugged fitness landscape such that populations occupy different peaks separated by valleys. Competition for food resources is a strong ecological force that can generate such divergent selection. However, it is unclear whether intrasexual competition over resources that provide mating opportunities can generate rugged fitness landscapes that foster speciation. Here we use highly variable male F2 hybrids of benthic and limnetic threespine sticklebacks, Gasterosteus aculeatus Linnaeus, 1758, to quantify the male competition fitness landscape. We find that disruptive sexual selection generates two fitness peaks corresponding closely to the male phenotypes of the two parental species, favouring divergence. Most surprisingly, an additional region of high fitness favours novel hybrid phenotypes that correspond to those observed in a recent case of reverse speciation after anthropogenic disturbance. Our results reveal that sexual selection through male competition plays an integral role in both forward and reverse speciation.

  18. How humans drive speciation as well as extinction

    DEFF Research Database (Denmark)

    Bull, Joseph William; Maron, M.

    2016-01-01

    A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known...... extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation—and emerging technologies could eventually provide additional mechanisms. The number of species relocated......, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic...

  19. Bulk metallic glass for low noise fluxgate Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The team of Prime Photonics, Virginia Tech, and Utron Kinetics propose to demonstrate a method for fabrication of a bulk, amorphous, cobalt-rich material that...

  20. Bulk nano-crystalline alloys

    OpenAIRE

    T.-S. Chin; Lin, C. Y.; Lee, M.C.; R.T. Huang; S. M. Huang

    2009-01-01

    Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and confirmed successful on another Fe-based BMG Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed cr...

  1. Different methods in assessing iodine speciation in urine of people ingested iodate iodized salt%测定摄入碘酸钾碘盐人群尿中碘形态的方法讨论

    Institute of Scientific and Technical Information of China (English)

    张亚平

    2015-01-01

    目前国内对食用碘酸钾碘盐人群尿中是否含碘酸根离子(IO3-)的测定方法有碘离子选择性电极测定法、对苯二胺比色测定法、在线分离在线消化-流动注射砷铈催化光度测定法.对这3种测定方法及其结果的可靠性和可信性进行分析发现,碘离子选择性电极测定法和对苯二胺比色测定法没有消除尿成分的严重干扰,测定特异性差.在线分离在线消化-流动注射砷铈催化光度测定法特异性好、灵敏度高、准确度好,其得到摄入碘酸钾碘盐人群尿中无IO3-形态排出.%At present, the methods to analyze IO3-in urine of human ingested edible salt iodized with potassium iodate include the iodine ion selective electrode analysis method, para-phenylene diamine colorimetric method and flow injection arsenite ceric catalytic spectrophotometry with online ion exchangeonline digestion(IE-FIA).In studies comparing the reliability of these methods and their results, it is found that iodine ion selective electrode analysis method and para-phenylene diamine colorimetric method did not eliminate the serious interference of urine compositions, and their determining specificity was lower.IE-FIA had the characteristics of high specificity, sensitivity and accuracy,and no IO3-ions was found in urine of people ingested KIO3 iodized salt.

  2. Speciation, Ecological Opportunity, and Latitude (American Society of Naturalists Address).

    Science.gov (United States)

    Schluter, Dolph

    2016-01-01

    Evolutionary hypotheses to explain the greater numbers of species in the tropics than the temperate zone include greater age and area, higher temperature and metabolic rates, and greater ecological opportunity. These ideas make contrasting predictions about the relationship between speciation processes and latitude, which I elaborate and evaluate. Available data suggest that per capita speciation rates are currently highest in the temperate zone and that diversification rates (speciation minus extinction) are similar between latitudes. In contrast, clades whose oldest analyzed dates precede the Eocene thermal maximum, when the extent of the tropics was much greater than today, tend to show highest speciation and diversification rates in the tropics. These findings are consistent with age and area, which is alone among hypotheses in predicting a time trend. Higher recent speciation rates in the temperate zone than the tropics suggest an additional response to high ecological opportunity associated with low species diversity. These broad patterns are compelling but provide limited insights into underlying mechanisms, arguing that studies of speciation processes along the latitudinal gradient will be vital. Using threespine stickleback in depauperate northern lakes as an example, I show how high ecological opportunity can lead to rapid speciation. The results support a role for ecological opportunity in speciation, but its importance in the evolution of the latitudinal gradient remains uncertain. I conclude that per capita evolutionary rates are no longer higher in the tropics than the temperate zone. Nevertheless, the vast numbers of species that have already accumulated in the tropics ensure that total rate of species production remains highest there. Thus, tropical evolutionary momentum helps to perpetuate the steep latitudinal biodiversity gradient.

  3. How humans drive speciation as well as extinction.

    Science.gov (United States)

    Bull, J W; Maron, M

    2016-06-29

    A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation-and emerging technologies could eventually provide additional mechanisms. The number of species relocated, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon 'no net loss' conservation literature-considering phylogenetic diversity and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity.

  4. Sexual selection and magic traits in speciation with gene flow

    Institute of Scientific and Technical Information of China (English)

    Maria R.SERVEDIO; Michael KOPP

    2012-01-01

    The extent to which sexual selection is involved in speciation with gene flow remains an open question and the subject of much research.Here,we propose that some insight can be gained from considering the concept of magic traits (i.e.,traits involved in both reproductive isolation and ecological divergence).Both magic traits and other,“non-magic”,traits can contribute to speciation via a number of specific mechanisms.We argue that many of these mechanisms are likely to differ widely in the extent to which they involve sexual selection.Furthermore,in some cases where sexual selection is present,it may be prone to inhibit rather than drive speciation.Finally,there are a priori reasons to believe that certain categories of traits are much more effective than others in driving speciation.The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow.In particular,we suggest that sexual selection can act as a driver of speciation in some scenarios,but may play a negligible role in potentially common categories of magic traits,and may be likely to inhibit speeiation in common categories of non-magic traits.

  5. Towards accounting for dissolved iron speciation in global ocean models

    Directory of Open Access Journals (Sweden)

    A. Tagliabue

    2011-03-01

    Full Text Available The trace metal iron (Fe is now routinely included in state-of-the-art ocean general circulation and biogeochemistry models (OGCBMs because of its key role as a limiting nutrient in regions of the world ocean important for carbon cycling and air-sea CO2 exchange. However, the complexities of the seawater Fe cycle, which impact its speciation and bioavailability, are highly simplified in such OGCBMs to avoid high computational costs. In a similar fashion to inorganic carbon speciation, we outline a means by which the complex speciation of Fe can be included in global OGCBMs in a reasonably cost-effective manner. We use our Fe speciation to suggest the global distribution of different Fe species is tightly controlled by environmental variability (temperature, light, oxygen and pH and the assumptions regarding Fe binding ligands. Impacts on bioavailable Fe are highly sensitive to assumptions regarding which Fe species are bioavailable. When forced by representations of future ocean circulation and climate we find large changes to the speciation of Fe governed by pH mediated changes to redox kinetics. We speculate that these changes may exert selective pressure on phytoplankton Fe uptake strategies in the future ocean. We hope our modeling approach can also be used as a ''test bed'' for exploring our understanding of Fe speciation at the global scale.

  6. XAS Studies of Se Speciation in Selenite-Fed Rats

    Science.gov (United States)

    Weekley, Claire M.; Aitken, Jade B.; Witting, Paul K.; Harris, Hugh H.

    2014-01-01

    The biological activity of selenium is dependent on its chemical form. Therefore, knowledge of Se chemistry in vivo is required for efficacious use of selenium compounds in disease prevention and treatment. Using X-ray absorption spectroscopy, Se speciation in the kidney, liver, heart, spleen, testis and red blood cells of rats fed control (~0.3 ppm Se) or selenite-supplemented (1 ppm or 5 ppm Se) diets for 3 or 6 weeks, was investigated. X-ray absorption spectroscopy revealed the presence of Se–Se and Se–C species in the kidney and liver, and Se–S species in the kidney, but not the liver. X-ray absorption near edge structure (XANES) spectra showed that there was variation in speciation in the liver and kidneys, but Se speciation was much more uniform in the remaining organs. Using principal component analysis (PCA) to interpret the Se K-edge X-ray absorption spectra, we were able to directly compare the speciation of Se in two different models of selenite metabolism – human lung cancer cells and rat tissues. The effects of Se dose, tissue type and duration of diet on selenium speciation in rat tissues were investigated, and a relationship between the duration of the diet (3 weeks versus 6 weeks) and selenium speciation was observed. PMID:25363824

  7. How humans drive speciation as well as extinction

    Science.gov (United States)

    Maron, M.

    2016-01-01

    A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation—and emerging technologies could eventually provide additional mechanisms. The number of species relocated, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature—considering phylogenetic diversity and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity. PMID:27358365

  8. Can environmental change affect host/parasite-mediated speciation?

    Science.gov (United States)

    Brunner, Franziska S; Eizaguirre, Christophe

    2016-08-01

    Parasitism can be a driver of species divergence and thereby significantly alter species formation processes. While we still need to better understand how parasite-mediated speciation functions, it is even less clear how this process is affected by environmental change. Both rapid and gradual changes of the environment can modify host immune responses, parasite virulence and the specificity of their interactions. They will thereby change host-parasite evolutionary trajectories and the potential for speciation in both hosts and parasites. Here, we summarise mechanisms of host-parasite interactions affecting speciation and subsequently consider their susceptibility to environmental changes. We mainly focus on the effects of temperature change and nutrient input to ecosystems as they are major environmental stressors. There is evidence for both disruptive and accelerating effects of those pressures on speciation that seem to be context-dependent. A prerequisite for parasite-driven host speciation is that parasites significantly alter the host's Darwinian fitness. This can rapidly lead to divergent selection and genetic adaptation; however, it is likely preceded by more short-term plastic and transgenerational effects. Here, we also consider how these first responses and their susceptibility to environmental changes could lead to alterations of the species formation process and may provide alternative pathways to speciation.

  9. How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

    Science.gov (United States)

    Kam, K.; Lemke, K.

    2014-12-01

    The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

  10. Improving Performance in Dense Wireless Spaces by Controlling Bulk Traffic

    Directory of Open Access Journals (Sweden)

    Marat Zhanikeev

    2017-01-01

    Full Text Available The growing number of wireless devices nowadays often results in congestion of wireless channels. In research, this topic is referred to as networking in dense wireless spaces. The literature on the topic shows that the biggest problem is the high number of concurrent sessions to a wireless access point. The obvious solution is to reduce the number of concurrent sessions. This paper proposes a simple method called Bulk-n-Pick which minimizes the number of prolonged concurrent sessions by separating bulk from sync traffic. Aiming at educational applications, under the proposed design, web applications would distribute the main bulk of content once at the beginning of a class and then rely on small messages for real time sync traffic during the class. For realistic performance analysis, this paper first performs real-life experiments with various counts of wireless devices, bulk sizes, and levels of sync intensity. Based on the experiments, this paper shows that the proposed Bulk-n-Pick method outperforms the traditional design even when only two concurrent bulk sessions are allowed. The experiment shows that up to 10 concurrent bulk sessions are feasible in practice. Based on these results, a method for online performance optimization is proposed and validated in a trace-based emulation.

  11. Development and Validation of a Rapid Chemometrics Assisted RP-HPLC with PDA Detection Method for the Simultaneous Estimation of Pyridoxine HCl and Doxylamine Succinate in Bulk and Pharmaceutical Dosage Form

    Directory of Open Access Journals (Sweden)

    P. Giriraj

    2014-01-01

    Full Text Available Simple, rapid, precise, and accurate RP-HPLC method was developed and optimized with the help of chemometric tool for the simultaneous estimation of pyridoxine HCl and doxylamine succinate in bulk and pharmaceutical dosage form. Optimization was done by central composite design in response surface methodology. Based on the trial and error, percentage of organic phase (methanol in mobile phase, flow rate, and molarity of the buffer were selected as factors. Resolution and retention time were used for the estimation of system response during the optimization procedure. The optimized condition was used and the separation was carried out on phenomenex C18 column (150 × 4.6 mm; i.d, 5 μ particle size using the mobile phase containing 49.37% of methanol and 50.63% of phosphate buffer (45.14 mM at a flow rate of 1 mL/min. Retention time was found to be 1.884 minutes for pyridoxine HCl and 3.959 minutes for doxylamine succinate. The calibration curves were found to be linear from 10 to 70 μg/mL and 10 to 90 μg/mL for pyridoxine HCl and doxylamine succinate with their correlation coefficient values 0.9995 and 0.9997. LOD and LOQ were found to be 23.5 ng/mL and 71.1 ng/mL for pyridoxine HCl and 99.9 ng/mL and 302.6 ng/mL for doxylamine succinate.

  12. Analysis on Economic Benefit of Curing under Different Loading Methods in Bulk Curing Barn%密集烤房不同装烟方式烘烤经济效益分析

    Institute of Scientific and Technical Information of China (English)

    詹良; 范才银; 李建华; 刘亮; 李旭; 李迪秦

    2014-01-01

    Three tobacco leaves loading methods ,two kinds of tobacco clips for knitting tobacco leaves and the traditional tobacco pole for weaving tobacco leaf ,were comparatively analyzed.The results showed that tobacco clips were simple mode with time-saving and energy-saving,its speed of knitting tobacco leaves was 1~2 times of the traditional tobacco pole , and it could save electric consumption and artificial cost for 117.53~181.06 RMB/room.Under knitting tobacco leaves with tobacco clips ,the capacity of bulk curing barn was increase by 20%~30%,and the quality of tobacco leaves was im-proved.%对两种不同口径型号的烟夹与传统挂杆3种装烟方式进行了对比分析。结果表明:烟夹编烟操作简单,省工省时,是传统烟杆编烟速度的1~2倍;采用烟夹编烟每炕烤烟可节省能耗与人工总成本117.53~181.06元/房;烟夹编烟能有效增加烤房容量,每炕烘烤鲜烟总重量比传统编烟烘烤可增加20%~30%;烤后烟叶质量相对有所提升。

  13. Longitudinal bulk acoustic mass sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Teva, Jordi; Boisen, Anja

    2009-01-01

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10(-15) g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise i...

  14. The Universe With Bulk Viscosity

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Exact solutions for a model with variable G, A and bulk viscosity areobtained. Inflationary solutions with constant (de Sitter-type) and variable energydensity are found. An expanding anisotropic universe is found to isotropize duringits expansion but a static universe cannot isotropize. The gravitational constant isfound to increase with time and the cosmological constant decreases with time asAo∝t-2.

  15. Nuclear locus divergence at the early stages of speciation in the Orchard Oriole complex.

    Science.gov (United States)

    Sturge, Rachel J; Cortés-Rodríguez, M Nandadevi; Rojas-Soto, Octavio R; Omland, Kevin E

    2016-07-01

    As two lineages diverge from one another, mitochondrial DNA should evolve fixed differences more rapidly than nuclear DNA due to its smaller effective population size and faster mutation rate. As a consequence, molecular systematists have focused on the criteria of reciprocal monophyly in mitochondrial DNA for delimiting species boundaries. However, mitochondrial gene trees do not necessarily reflect the evolutionary history of the taxa in question, and even mitochondrial loci are not expected to be reciprocally monophyletic when the speciation event happened very recently. The goal of this study was to examine mitochondrial paraphyly within the Orchard Oriole complex, which is composed of Icterus spurius (Orchard Oriole) and Icterus fuertesi (Fuertes' Oriole). We increased the geographic sampling, added four nuclear loci, and used a range of population genetic and coalescent methods to examine the divergence between the taxa. With increased taxon sampling, we found evidence of clear structure between the taxa for mitochondrial DNA. However, nuclear loci showed little evidence of population structure, indicating a very recent divergence between I. spurius and I. fuertesi. Another goal was to examine the genetic variation within each taxon to look for evidence of a past founder event within the I. fuertesi lineage. Based on the high amounts of genetic variation for all nuclear loci, we found no evidence of such an event - thus, we found no support for the possible founding of I. fuertesi through a change in migratory behavior, followed by peripheral isolates speciation. Our results demonstrate that these two taxa are in the earliest stages of speciation, at a point when they have fixed differences in plumage color that are not reflected in monophyly of the mitochondrial or nuclear DNA markers in this study. This very recent divergence makes them ideal for continued studies of species boundaries and the earliest stages of speciation.

  16. Effects of water management on arsenic and cadmium speciation and accumulation in an upland rice cultivar

    Institute of Scientific and Technical Information of China (English)

    Pengjie Hu; Younan Ouyang; Longhua Wu; Libo Shen; Yongming Luo; Peter Christie

    2015-01-01

    Pot and field experiments were conducted to investigate the effects of water regimes on the speciation and accumulation of arsenic (As) and cadmium (Cd) in Brazilian upland rice growing in soils polluted with both As and Cd.In the pot experiment constant and intermittent flooding treatments gave 3-16 times higher As concentrations in soil solution than did aerobic conditions but Cd showed the opposite trend.Compared to arsenate,there were more marked changes in the arsenite concentrations in the soil solution as water management shifted,and therefore arsenite concentrations dominated the As speciation and bioavailability in the soil.In the field experiment As concentrations in the rice grains increased from 0.14 to 0.21 mg/kg while Cd concentrations decreased from 0.21 to 0.02 mg/kg with increasing irrigation ranging from aerobic to constantly flooding conditions.Among the various water regimes the conventional irrigation treatment produced the highest rice grain yield of 6.29 tons/ha.The As speciation analysis reveals that the accumulation of dimethylarsinic acid (from 11.3% to 61.7%) made a greater contribution to the increase in total As in brown rice in the intermittent and constant flooding treatments compared to the intermittent-aerobic treatment.Thus,water management exerted opposite effects on Cd and As speciation and bioavailability in the soil and consequently on their accumulation in the upland rice.Special care is required when irrigation regime methods are employed to mitigate the accumulation of metal(loid)s in the grain of rice grown in soils polluted with both As and Cd.

  17. Chemical and physical speciation of mercury in Offatts Bayou: A seasonally anoxic bayou in Galveston Bay

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghee; Lehman, Ronald D.; Choe, Key-Young; Gill, Gary A.

    2007-07-01

    A chemical equilibrium model was used to predict the solution speciation of dissolved mercury (Hg) in the stratified water column of Offatts Bayou, a subestuary in Galveston Bay, Texas, which undergoes seasonal anoxia in bottom waters. Chemical equilibrium modeling was conducted using conditional stability constants and concentrations of Hg-complexing organic ligands experimentally determined by competitive ligand equilibration methods. Dissolved Hg complexation was dominated by interactions with sulfide and dissolved organic matter (DOM) (HOHgHS0, HOHgHS(DOM), HgSHS2, and HgS 2{ 2 ) at all depths. Sulfide and glutathione competed for methylmercury (MeHg) complexation in oxic layers; in anoxic waters, sulfide complexation dominated MeHg speciation. The particle–water distribution coefficient (Kd) of Hg decreased in the anoxic layer of the water column, where the dissolved sulfide concentration increased, providing evidence that sulfide complexation influences the solubility of Hg. The solubility of MeHg was elevated in the anoxic as compared to the oxic layers, and this distributional feature was coincident with a change in the solution speciation of dissolved MeHg from glutathione/sulfide complexation in the oxic layers to a predominantly sulfide complexation in the anoxic layers. Maximum enrichment of Hg, MeHg, and iron (Fe) in suspended particulate matter was observed in the lower layer of the pycnocline, most likely resulting from formation of insoluble Fe oxide, which scavenged dissolved Hg sulfide and MeHg-sulfide species. The concomitant decrease in dissolved inorganic Hg, Fe, and sulfide in the anoxic layers is suggested to result from scavenging of inorganic Hg by FeS, which is in accordance with the Hg speciation model. Overall, Hg cycling in the water column of Offatts Bayou was associated with sulfide and DOM complexation, Fe dissolution/precipitation, water column production of MeHg, and/or efflux of MeHg from anoxic sediment.

  18. Sorption Speciation of Lanthanides/Actinides on Minerals by TRLFS, EXAFS and DFT Studies: A Review

    Directory of Open Access Journals (Sweden)

    Xiaoli Tan

    2010-11-01

    Full Text Available Lanthanides/actinides sorption speciation on minerals and oxides by means of time resolved laser fluorescence spectroscopy (TRLFS, extended X-ray absorption fine structure spectroscopy (EXAFS and density functional theory (DFT is reviewed in the field of nuclear disposal safety research. The theoretical aspects of the methods are concisely presented. Examples of recent research results of lanthanide/actinide speciation and local atomic structures using TRLFS, EXAFS and DFT are discussed. The interaction of lanthanides/actinides with oxides and minerals as well as their uptake are also of common interest in radionuclide chemistry. Especially the sorption and inclusion of radionuclides into several minerals lead to an improvement in knowledge of minor components in solids. In the solid-liquid interface, the speciation and local atomic structures of Eu(III, Cm(III, U(VI, and Np(IV/VI in several natural and synthetic minerals and oxides are also reviewed and discussed. The review is important to understand the physicochemical behavior of lanthanides/actinides at a molecular level in the natural environment.

  19. Selective speciation improves efficacy and lowers toxicity of platinum anticancer and vanadium antidiabetic drugs.

    Science.gov (United States)

    Doucette, Kaitlin A; Hassell, Kelly N; Crans, Debbie C

    2016-12-01

    Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color. For both vanadium and platinum systems, understanding the processes as the compounds, Lipoplatin and Satraplatin, enter cells is needed to better combat the disease; there are many cellular metabolites, which may affect processing and thus the efficacy of the drugs. Examples of two formulations of platinum compounds illustrate how changing the chemistry of the platinum will result in less toxic and better tolerated drugs. The consequence of the much lower toxicity of the drug, can be readily realized because cisplatin administration requires hospital stay whereas Lipoplatin can be done in an outpatient manner. Similarly, the properties of Satraplatin allow for development of an oral drug. These forms of platinum demonstrate that the direct consequence of more selective speciation is lower side effects and cheaper administration of the anticancer agent. Therefore we urge that as the community goes forward in development of new drugs, control of speciation chemistry will be considered as one of the key strategies in the future development of anticancer drugs.

  20. Speciation and Health Risks of Atmospheric Nanoparticulates

    Science.gov (United States)

    Nguyen, Kennedy

    Exposure to air pollution causes several adverse health effects such as asthma, respiratory disease, cardiovascular disease, cancer, and premature death; and the San Joaquin Valley is one of the most heavily polluted regions in the US. The mountains that surround the valley allow air pollution, including particulate matter, to remain stagnant, prolonging the exposure of valley populations to it. The primary sources of particulate matter for this region are aluminosilicate dust from agricultural activities, and soot emissions from diesel trucks and vehicular traffic. A substantial fraction of emitted material is nanoparticulate matter (health impacts of particulate matter. There is a need for chemical speciation of particulate matter that will allow the identification of the chemical and physical properties of particulates by source, the creation of well-controlled proxy particles with those properties for testing in cell culture studies, and correlation of particulate properties and sources with their negative health impacts. These results can help identify the sources of air pollution to prioritize for mitigation for the greatest health benefit. In addition, further chemical speciation can help monitor the results of such mitigation efforts. Here, natural particulate matter samples from Merced and Fresno, two cities in the San Joaquin Valley, were analyzed. Ultrafine particles present were 40 to 50 nm in diameter and mostly composed of aluminum, silicon, oxygen, and iron hydroxide. XAS data confirmed the presence of the aluminosilicate as smectite clay and the iron hydroxide as ferrihydrite. Furthermore, a chemical speciation study investigated industrial emissions of air particulate matter. Samples were analyzed using electron microscopy for elemental composition and size distribution, and found to contain fine metal particulates (lead and iron) that can lead to lung inflammation. From characterization data, in order to create a simplified proxy particle system

  1. Cobalamin Concentrations in Fetal Liver Show Gender Differences: A Result from Using a High-Pressure Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry as an Ultratrace Cobalt Speciation Method.

    Science.gov (United States)

    Bosle, Janine; Goetz, Sven; Raab, Andrea; Krupp, Eva M; Scheckel, Kirk G; Lombi, Enzo; Meharg, Andrew A; Fowler, Paul A; Feldmann, Jörg

    2016-12-20

    Maternal diet and lifestyle choices may affect placental transfer of cobalamin (Cbl) to the fetus. Fetal liver concentration of Cbl reflects nutritional status with regards to vitamin B12, but at these low concentration current Cbl measurement methods lack robustness. An analytical method based on enzymatic extraction with subsequent reversed-phase-high-pressure liquid chromatography (RP-HPLC) separation and parallel ICPMS and electrospray ionization (ESI)-Orbitrap-MS to determine specifically Cbl species in liver samples of only 10-50 mg was developed using 14 pig livers. Subsequently 55 human fetal livers were analyzed. HPLC-ICPMS analysis for cobalt (Co) and Cbl gave detection limits of 0.18 ng/g and 0.88 ng/g d.m. in liver samples, respectively, with a recovery of >95%. Total Co (Cot) concentration did not reflect the amount of Cbl or vitamin B12 in the liver. Cbl bound Co contributes only 45 ± 15% to Cot. XRF mapping and μXANES analysis confirmed the occurrence of non-Cbl cobalt in pig liver hot spots indicating particular Co. No correlations of total cobalt nor Cbl with fetal weight or weeks of gestation were found for the human fetal livers. Although no gender difference could be identified for total Co concentration, female livers were significantly higher in Cbl concentration (24.1 ± 7.8 ng/g) than those from male fetuses (19.8 ± 7.1 ng/g) (p = 0.04). This HPLC-ICPMS method was able to quantify total Cot and Cbl in fetus liver, and it was sensitive and precise enough to identify this gender difference.

  2. Development of speciation analysis for selenium in nutritional supplements by the determination of the seleno-methionine; Developpement de l'analyse de speciation du selenium dans des complements alimentaires par la determination de la selenomethionine

    Energy Technology Data Exchange (ETDEWEB)

    Sannac, S.; Labarraque, G.; Fisicaro, P. [Laboratoire National de Metrologie et d' Essai (LNE), 75 - Paris (France); Sannac, S.; Pannier, F.; Potin-Gautier, M. [Pau Univ. et des Pays de l' Adour, CNRS/UMR 5254, Lab. de Chimie Analytique, Bio-Inorganique et Environnement (IPREM), 64 (France)

    2009-07-01

    The development of a reference method in analytical chemistry is presented. Liquid chromatography with inductively coupled plasma mass spectrometry is employed to perform in speciation analysis. Applications are developed for the determination of seleno-methionine in nutritional supplements. The use of isotope dilution, a primary method, is required to enable measurement traceability. Method validation is ensured by the study of a certified reference material. (authors)

  3. Uranium Speciation and Bioavailability in Aquatic Systems: An Overview

    Directory of Open Access Journals (Sweden)

    Scott J. Markich

    2002-01-01

    Full Text Available The speciation of uranium (U in relation to its bioavailability is reviewed for surface waters (fresh- and seawater and their sediments. A summary of available analytical and modeling techniques for determining U speciation is also presented. U(VI is the major form of U in oxic surface waters, while U(IV is the major form in anoxic waters. The bioavailability of U (i.e., its ability to bind to or traverse the cell surface of an organism is dependent on its speciation, or physicochemical form. U occurs in surface waters in a variety of physicochemical forms, including the free metal ion (U4+ or UO22+ and complexes with inorganic ligands (e.g., uranyl carbonate or uranyl phosphate, and humic substances (HS (e.g., uranyl fulvate in dissolved, colloidal, and/or particulate forms. Although the relationship between U speciation and bioavailability is complex, there is reasonable evidence to indicate that UO22+ and UO2OH+ are the major forms of U(VI available to organisms, rather than U in strong complexes (e.g., uranyl fulvate or adsorbed to colloidal and/or particulate matter. U(VI complexes with inorganic ligands (e.g., carbonate or phosphate and HS apparently reduce the bioavailability of U by reducing the activity of UO22+ and UO2OH+. The majority of studies have used the results from thermodynamic speciation modeling to support these conclusions. Time-resolved laser-induced fluorescence spectroscopy is the only analytical technique able to directly determine specific U species, but is limited in use to freshwaters of low pH and ionic strength. Nearly all of the available information relating the speciation of U to its bioavailability has been derived using simple, chemically defined experimental freshwaters, rather than natural waters. No data are available for estuarine or seawater. Furthermore, there are no available data on the relationship between U speciation and bioavailability in sediments. An understanding of this relationship has been

  4. Molecular imprinting of bulk, microporous silica

    Science.gov (United States)

    Katz, Alexander; Davis, Mark E.

    2000-01-01

    Molecular imprinting aims to create solid materials containing chemical functionalities that are spatially organized by covalent or non-covalent interactions with imprint (or template) molecules during the synthesis process. Subsequent removal of the imprint molecules leaves behind designed sites for the recognition of small molecules, making the material ideally suited for applications such as separations, chemical sensing and catalysis. Until now, the molecular imprinting of bulk polymers and polymer and silica surfaces has been reported, but the extension of these methods to a wider range of materials remains problematic. For example, the formation of substrate-specific cavities within bulk silica, while conceptually straightforward, has been difficult to accomplish experimentally. Here we describe the imprinting of bulk amorphous silicas with single aromatic rings carrying up to three 3-aminopropyltriethoxysilane side groups; this generates and occupies microporosity and attaches functional organic groups to the pore walls in a controlled fashion. The triethoxysilane part of the molecules' side groups is incorporated into the silica framework during sol-gel synthesis, and subsequent removal of the aromatic core creates a cavity with spatially organized aminopropyl groups covalently anchored to the pore walls. We find that the imprinted silicas act as shape-selective base catalysts. Our strategy can be extended to imprint other functional groups, which should give access to a wide range of functionalized materials.

  5. Speciation methods and sample analysis of soluble mercury in traditional Chinese medicines%中成药可溶性汞形态分析方法及样品结果测定

    Institute of Scientific and Technical Information of China (English)

    徐陆正; 解清; 闫赖赖; 陈玉红; 王京宇

    2011-01-01

    建立了微波辅助提取、HPLC-ICP-MS联用分析中成药中二价汞和甲基汞的方法.分别比较了提取液中盐酸和L-半胱氨酸含量、提取温度和提取时间对提取结果的影响,得到了微波辅助提取的最优条件:体积分数为1%的盐酸10 mL和质量分数为5%的L-半胱氨酸1 mL作为提取液,控温70℃,微波辅助提取1h.该方法测得的二价汞和甲基汞的精密度分别为1.7%和4.4%,加标回收率分别为80.7%~99.5%和93.7%~95.8%.并应用该方法分析测定了20种、共49批次的含朱砂的中成药中可溶性汞的形态.%A method with microwave-assisted extraction and HPLC-ICP-MS to analyse the inorganic mercury and methyl mercury in the traditional Chinese medicines (TCMs) has been built. The hydrochloric acid and L-cysteine concentration, the extraction temperature and extraction time have been investigated. The optimal conditions are as follows: 1% hydrochloric acid 10 ml and 5% L-cysteine 1 ml as extract, temperature control 70 ℃, and time control lh. Using this method, the inorganic mercury and methyl mercury's RSDs(relative standard deviation) are 1. 7% and 4. 4%, and the standardized recoveries are 80. 7~99. 5% and 93. 7~ 95. 8%. Then, 49 batches of 20 kinds TCMs which contain cinnabar have been determinated using this method.

  6. Polyploidy and Speciation in Pteris (Pteridaceae

    Directory of Open Access Journals (Sweden)

    Yi-Shan Chao

    2012-01-01

    Full Text Available The highest frequency of polyploidy among plants is considered to occur in the Pteridophytes. In this study, we focused on polyploidy displayed by a specific fern taxon, the genus Pteris L. (Pteridaceae, comprising over 250 species. Cytological data from 106 Pteris species were reviewed. The base number of chromosomes in Pteris is 29. Polyploids are frequently found in Pteris, including triploids, tetraploids, pentaploids, hexaploids, and octoploids. In addition, an aneuploid species, P. deltodon Bak., has been recorded. Furthermore, the relationship between polyploidy and reproductive biology is reviewed. Among these 106 Pteris species, 60% exhibit polyploidy: 22% show intraspecific polyploidy and 38% result from polyploid speciation. Apogamous species are common in Pteris. Diploids are the most frequent among Pteris species, and they can be sexual or apogamous. Triploids are apogamous; tetraploids are sexual or apogamous. Most Pteris species have one to two ploidy levels. The diverse ploidy levels suggest that these species have a complex evolutionary history and their taxonomic problems require further clarification.

  7. Bulk sound velocity of porous materials at high pressures

    Institute of Scientific and Technical Information of China (English)

    耿华运; 吴强; 谭华; 蔡灵仓; 经福谦

    2002-01-01

    A correction of Walsh's method for bulk sound velocity calculation for shocked porous materials is accomplishedbased on the Wu-Jing thermodynamic equation of state. The corrected bulk velocities for solid and porous sampleswith low porosities are in good agreement with the corresponding experimental data published previously. On the basisof this corrected equation, the influence of thermoelectrons on the bulk velocity of shocked materials is discussed indetail at pressures of 50, 70 and 200 GPa. Some interesting phenomena are revealed, which seem to be the uniquefeatures of a dynamic-pressure-loading process and could not be found in static experiments.

  8. Negative Effects of Sludge Bulking in Membrane Bio-Reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying; HUANG Zhi; REN Nanqi; MENG Qingjuan

    2006-01-01

    Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly through the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures, the high block rate of membrane pore and the great quantity of filamentous bacteria at the external surface presented at the same time. Thus, plenty of methods should be performed to control sludge bulking once it happened in membrane bio-reactor.

  9. Divergence is focused on few genomic regions early in speciation: incipient speciation of sunflower ecotypes.

    Science.gov (United States)

    Andrew, Rose L; Rieseberg, Loren H

    2013-09-01

    Early in speciation, as populations undergo the transition from local adaptation to incipient species, is when a number of transient, but potentially important, processes appear to be most easily detected. These include signatures of selective sweeps that can point to asymmetry in selection between habitats, divergence hitchhiking, and associations of adaptive genes with environments. In a genomic comparison of ecotypes of the prairie sunflower, Helianthus petiolaris, occurring at Great Sand Dunes National Park and Preserve (Colorado), we found that selective sweeps were mainly restricted to the dune ecotype and that there was variation across the genome in whether proximity to the nondune population constrained or promoted divergence. The major regions of divergence were few and large between ecotypes, in contrast with an interspecific comparison between H. petiolaris and a sympatric congener, Helianthus annuus. In general, the large regions of divergence observed in the ecotypic comparison swamped locus-specific associations with environmental variables. In both comparisons, regions of high divergence occurred in portions of the genetic map with high marker density, probably reflecting regions of low recombination. The difference in genomic distributions of highly divergent regions between ecotypic and interspecific comparisons highlights the value of studies spanning the spectrum of speciation in related taxa.

  10. Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

    Directory of Open Access Journals (Sweden)

    Magdalena Jabłońska-Czapla

    2015-01-01

    Full Text Available Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples. An important issue addressed is the preparation of environmental samples for speciation analysis.

  11. Epigenetic divergence as a potential first step in darter speciation.

    Science.gov (United States)

    Smith, Tracy A; Martin, Michael D; Nguyen, Michael; Mendelson, Tamra C

    2016-04-01

    Recent studies show that epigenetic variation in the form of DNA methylation may serve as a substrate for selection. Theory suggests that heritable epigenetic marks that increase fitness should increase in frequency in a population, and these changes may result in novel morphology, behaviour, or physiology, and ultimately reproductive isolation. Therefore, epigenetic variation might provide the first substrate for selection during the course of evolutionary divergence. This hypothesis predicts that populations in the earliest stages of divergence will differentiate in their methylome prior to any genetic differentiation. While several studies have investigated natural epigenetic variation, empirical studies that test predictions about its role in speciation are surprisingly scarce. Here, we investigate DNA methylation variation using an isoschizomeric digest method, Methyl-Sensitive Amplified Polymorphism, across multiple stages of evolutionary divergence in natural populations of North American stream fishes. We show that epigenetic differentiation between methylomes is greater than genetic divergence among closely related populations across two river drainages. Additionally, we demonstrate that epigenetic divergence is a stronger predictor of the strength of behavioural reproductive isolation and suggest that changes in the methylome could influence the evolution of reproductive isolation between species. Our findings suggest a role for epigenetics not only in the initiation of divergence, but also in the maintenance of species boundaries over greater evolutionary timescales.

  12. Bulk Superconductors in Mobile Application

    Science.gov (United States)

    Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

    We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

  13. The use of ion chromatography-dc plasma atomic emission spectrometry for the speciation of trace metals

    Energy Technology Data Exchange (ETDEWEB)

    Urasa, I.T.

    1991-09-20

    The original objects of this research program were: to interface d.c. plasma atomic emission spectrometer with an ion chromatograph; to characterize and optimize the combined systems for application in the speciation of metals in aqueous solutions; to use this system in the study of the solution chemistry of various metals; and to find ways in which the measurement sensitivity of the method can be enhanced, thereby allowing the detection of metal species at low ppb concentration levels. This approach has been used to study the chemistry of and speciate several elements in solution including: arsenic, chromium, iron, manganese, nickel phosphorus, platinum, selenium, and vanadium. During the course of this research, we have found that the solution chemistry of the elements studied and the speciation data obtained can vary considerably depending on the solution, and the chromatographic conditions employed. The speciation of chromium, iron, and vanadium was found to be highly influenced by the acidity of the sample. The element selective nature of the d.c. plasma detector allows these changes to be monitored, thereby providing quantitative information on the new moieties formed. New approaches are being developed including the use of chelating ligands as preconcentration agents for purposes of reducing further the detection limits of the elements of interest and to improve the overall element speciation scheme. New thrusts are being directed towards the employment of post-column derivatization method coupled with colorimetric measurements to detect and quantify metal species eluting from the chromatographic column. The influence of sample acidity on these investigations will be carefully evaluated. These new thrusts are described in the accompanying Project Renewal Proposal.

  14. Surface barrier and bulk pinning in MgB$_2$ superconductor

    OpenAIRE

    Pissas, M.; Moraitakis, E.; Stamopoulos, D.; Papavassiliou, G.; V. Psycharis; Koutandos, S.

    2001-01-01

    We present a modified method of preparation of the new superconductor MgB$_2$. The polycrystalline samples were characterized using x-ray and magnetic measurements. The surface barriers control the isothermal magnetization loops in powder samples. In bulk as prepared samples we always observed symmetric magnetization loops indicative of the presence of a bulk pinning mechanism. Magnetic relaxation measurements in the bulk sample reveal a crossover of surface barrier to bulk pinning.

  15. Calculated Bulk Properties of the Actinide Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Andersen, O. K.; Johansson, B.

    1978-01-01

    Self-consistent relativistic calculations of the electronic properties for seven actinides (Ac-Am) have been performed using the linear muffin-tin orbitals method within the atomic-sphere approximation. Exchange and correlation were included in the local spin-density scheme. The theory explains...... the variation of the atomic volume and the bulk modulus through the 5f series in terms of an increasing 5f binding up to plutonium followed by a sudden localisation (through complete spin polarisation) in americium...

  16. Fabrication of Porous Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    Keqiang QIU; Yinglei REN

    2005-01-01

    An open-cell porous bulk metallic glass (BMG)with a diameter of at least 6 mm was fabricated by using an U-turn quartz tube and infiltration casting aroundsoluble NaCl placeholders. The pore formation and glassy structure were examined by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the pores or cells are connected to each other and the specimenis composed of a mostly glassy phase.This paper provides a suitable method for fabrication of porous BMG and BMG with larger size in diameter.

  17. Analytical tools for speciation in the field of toxicology

    Energy Technology Data Exchange (ETDEWEB)

    Bresson, C. [CEA, DEN, DPC, SEARS, Gif-sur-Yvette (France). Laboratoire de Developpement Analytique Nucleaire, Isotopique et Elementaire; Chartier, F. [CEA, DEN, Gif-sur-Yvette (France). Dept. de Physico-Chimie; Ansoborlo, E. [CEA, DEN, DRCP, CETAMA, Marcoule, Bagnols-sur-ceze (France); Ortega, R. [Bordeaux Univ., CENBG, UMR 5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, Gradignan (France)

    2013-08-01

    The knowledge of the speciation of elements at trace and ultra-trace level, in biological and environmental media is essential to acquire a better understanding of the mechanisms of toxicity, transport and accumulation in which they are involved. Determining the speciation of an element in a given medium is challenging and requires the knowledge of different methodological approaches: the calculation approach and the experimental approach through the use of dedicated analytical and spectroscopic tools. In this framework, this mini-review reports the approaches to investigate the speciation of elements in biological and environmental media as well as the experimental techniques of speciation analysis, illustrated by recent examples. The main analytical and spectroscopic techniques to obtain structural, molecular, elemental and isotopic information are described. A brief overview of separation techniques coupled with spectrometric techniques is given. Imaging and micro-localisation techniques, which aim at determining the in situ spatial distribution of elements and molecules in various solid samples, are also presented. The last part deals with the development of micro-analytical systems, since they open crucial perspectives to speciation analysis for low sample amounts and analysis on field. (orig.)

  18. Female mate-choice behavior and sympatric speciation.

    Science.gov (United States)

    Verzijden, Machteld N; Lachlan, Robert F; Servedio, Maria R

    2005-10-01

    Many models have investigated how the process of speciation may occur in sympatry. In these models, individuals are either asexual or mate choice is determined by very simple rules. Females, for example, may be assumed either to compare their phenotype to that of a potential mate, preferring to mate with similar males (phenotype matching), or to possess preference genes that determine which male phenotype they prefer. These rules often do not reflect the mate-choice rules found in empirical studies. In this paper, we compare these two modes of female choice with various types of sexual imprinting. We examine the efficacy of different mate-choice behavior in causing divergence in male traits under simple deterministic one-locus population genetic models as well as under polygenic, individual-based simulations based on the models of Dieckmann and Doebeli (1999). We find that the inheritance mechanism of mate choice can have a large effect on the ease of sympatric speciation. When females imprint on their mothers, the result of the model is similar to phenotype matching, where speciation can occur fairly easily. When females imprint on their fathers or imprint obliquely, speciation becomes considerably less likely. Finally, when females rely on preference genes, male trait evolution occurs easily, but the correlation between trait and preference can be weak, and interpreting these results as speciation may be suspect.

  19. Elemental speciation analysis, from environmental to biochemical challenge

    Science.gov (United States)

    Jitaru, P.; Barbante, C.

    2006-12-01

    Information regarding the distribution of metallic/metalloid chemical species in biological compartments is required for understanding their biochemical impact on living organisms. To obtain such information implies the use of a dedicated measurement approach, namely speciation analysis. The current trend in (elemental) speciation analysis regards bioinorganic applications. New analytical methodologies are therefore necessary for identification, detection and characterization of metal(loids) complexed or incorporated into biomolecules. The established element-speciation approaches developed for the determination of low molecular mass metal(loid) species (e.g. organometallic compounds) in environmental, food, toxicological and health sciences are presently being adapted for the determination of high molecular mass metal-species, generally related to biological processes. This is one of the newest approaches in terms of element speciation and is called metallomics; this concept refers to the totality of metal species in a cell and covers the inorganic element content and the ensemble of its complexes with biomolecules, particularly proteins, participating in the organisms' response to beneficial or harmful conditions. Compared to conventional elemental speciation analysis, the approach applied to bioinorganic analysis is challenging, particularly given the difficulties in identification/characterization of the organic (e.g. protein) content of such species. In addition, quantification is not feasible with the conventional approaches, which led to the exploitation of the unique feature of (post-column) online isotope dilution-mass spectrometry for species quantification in metallomics.

  20. Tailoring Magnetic Properties in Bulk Nanostructured Solids

    Science.gov (United States)

    Morales, Jason Rolando

    Important magnetic properties and behaviors such as coercivity, remanence, susceptibility, energy product, and exchange coupling can be tailored by controlling the grain size, composition, and density of bulk magnetic materials. At nanometric length scales the grain size plays an increasingly important role since magnetic domain behavior and grain boundary concentration determine bulk magnetic behavior. This has spurred a significant amount of work devoted to developing magnetic materials with nanometric features (thickness, grain/crystallite size, inclusions or shells) in 0D (powder), 1D (wires), and 2D (thin films) materials. Large 3D nanocrystalline materials are more suitable for many applications such as permanent magnets, magneto-optical Faraday isolators etc. Yet there are relatively few successful demonstrations of 3D magnetic materials with nanoscale influenced properties available in the literature. Making dense 3D bulk materials with magnetic nanocrystalline microstructures is a challenge because many traditional densification techniques (HIP, pressureless sintering, etc.) move the microstructure out of the "nano" regime during densification. This dissertation shows that the Current Activated Pressure Assisted Densification (CAPAD) method, also known as spark plasma sintering, can be used to create dense, bulk, magnetic, nanocrystalline solids with varied compositions suited to fit many applications. The results of my research will first show important implications for the use of CAPAD for the production of exchange-coupled nanocomposite magnets. Decreases in grain size were shown to have a significant role in increasing the magnitude of exchange bias. Second, preferentially ordered bulk magnetic materials were produced with highly anisotropic material properties. The ordered microstructure resulted in changing magnetic property magnitudes (ex. change in coercivity by almost 10x) depending on the relative orientation (0° vs. 90°) of an externally

  1. Arsenic speciation and reactivity in poultry litter

    Science.gov (United States)

    Arai, Y.; Lanzirotti, A.; Sutton, S.; Davis, J.A.; Sparks, D.L.

    2003-01-01

    Recent U.S. government action to lower the maximum concentration levels (MCL) of total arsenic (As) (10 ppb) in drinking water has raised serious concerns about the agricultural use of As-containing biosolids such as poultry litter (PL). In this study, solid-state chemical speciation, desorbability, and total levels of As in PL and long-term amended soils were investigated using novel synchrotronbased probing techniques (microfocused (??) synchrotron X-ray fluorescence (SXRF) and ??-X-ray absorption near-edge structure (XANES) spectroscopies) coupled with chemical digestion and batch experiments. The total As levels in the PL were as high as ???50 mg kg-1, and As(II/III and V) was always concentrated in abundant needle-shaped microscopic particles (???20/ ??m x 850 ??m) associated with Ca, Cu, and Fe and to a lesser extent with S, CI, and Zn. Postedge XANES features of litter particles are dissimilar to those of the organo-As(V) compound in poultry feed (i.e., roxarsone), suggesting possible degradation/transformation of roxarsone in the litter and/or in poultry digestive tracts. The extent of As desorption from the litter increased with increasing time and pH from 4.5 to 7, but at most 15% of the total As was released after 5 d at pH 7, indicating the presence of insoluble phases and/or strongly retained soluble compounds. No significant As accumulation (< 15 mg kg-1) was found in long-term PL-a mended agricultural surface soils. This suggests that As in the PL may have undergone surface and subsurface transport processes. Our research results raise concerns about long-term PL amendment effects on As contamination in surrounding soilwater environments.

  2. Voltammetric Investigation Of Hydrothermal Iron Speciation

    Directory of Open Access Journals (Sweden)

    Charlotte eKleint

    2016-05-01

    Full Text Available Hydrothermal vent fluids are highly enriched in iron (Fe compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world`s surface ocean. We have investigated the concentration and speciation of Fe in several vent fluid and plume samples from the Nifonea vent field, Coriolis Troughs, New Hebrides Island Arc, South Pacific Ocean using competitive ligand exchange - adsorptive cathodic stripping voltammetry (CLE - AdCSV with salicylaldoxime (SA as the artificial ligand. Our results for total dissolved Fe (dFe in the buoyant hydrothermal plume samples showed concentrations up to 3.86 µM dFe with only a small fraction between 1.1% and 11.8% being chemically labile. Iron binding ligand concentrations ([L] were found in µM level with strong conditional stability constants up to log K[L],Fe3+ of 22.9. Within the non-buoyant hydrothermal plume above the Nifonea vent field, up to 84.7% of the available Fe is chemically labile and [L] concentrations up to 97 nM were measured. [L] was consistently in excess of Felab, indicating that all available Fe is being complexed, which in combination with high Felab values in the non-buoyant plume, signifies that a high fraction of hydrothermal dFe is potentially being transported away from the plume into the surrounding waters, contributing to the global oceanic Fe budget.

  3. Bulk metamaterials: Design, fabrication and characterization

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Alabastri, Alessandro

    2009-01-01

    Bulk metamaterials claim a lot of attention worldwide. We report about our activity and advances in design, fabrication and characterization of metal-dielectric composites with three-dimensional lattices. The nomenclature of designs exhibiting negative index behaviour in the near infrared includes...... the generic family of so-called nested structures. Such designs allow keeping the cubic symmetry of the unit cell along with the electric and magnetic responses showed by different parts in separate. For extraction of effective parameters we employ homemade wave propagation retrieving method free from...... ambiguity generic to the standard S-parameters retrieval method. Accurateness of the method is highlighted by a set of numerical checks. To fabricate smooth metal three-dimensional structures we develop an electroless chemical technique. We present the results of silver deposition on the surface of a 30...

  4. Bulk modification of PDMS microchips by an amphiphilic copolymer.

    Science.gov (United States)

    Xiao, Yan; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2007-09-01

    A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk-modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk-modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.

  5. Micro and bulk analysis of prostate tissues classified as hyperplasia

    Energy Technology Data Exchange (ETDEWEB)

    Kwiatek, W.M. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Cracow (Poland)], E-mail: wojciech.kwiatek@ifj.edu.pl; Banas, A.; Banas, K. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Cracow (Poland); Cinque, G. [INFN- Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati (Italy); Dyduch, G. [Collegium Medicum, Jagiellonian University, Cracow (Poland); Falkenberg, G. [Hasylab, DESY Notkestraae 85, D-22603 Hamburg (Germany); Kisiel, A. [Institute of Physics, Jagiellonian University, ul.Reymonta 4, 30-059 Cracow (Poland); Marcelli, A. [INFN- Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati (Italy); Podgorczyk, M. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Cracow (Poland)

    2007-07-15

    BPH (Benign Prostatic Hyperplasia) is the most common benign neoplasm (non cancerous enlargement of the prostate gland), whose prevalence increases with age. The gland, when increased in size, exerts pressure on the urethra, causing obstruction to urine flow. The latter may result in severe urinary tract and kidney conditions. In this work prostate samples from patients diagnosed with BPH were analyzed using synchrotron radiation. Micro-analysis of the hyperplastic samples was carried out on the L-beam line at HASYLAB, DESY (Germany), while bulk analysis on selected samples was performed at the DRX2 beamline at LNF, Frascati (Italy). Microanalysis with a mono-energetic beam 15 {mu}m in diameter confirmed that concentrations of certain elements, such as S, Mn, Cu, Fe and Zn, are good indicators of pathological disorders in prostate tissue that may be considered effective tracers of developing compliant. The concentrations of Mn, Cu, Fe and Zn are higher in hyperplastic tissues, as compared to normal ones, while for sulphur the opposite is observed. Additionally, Fe and S K-edge XANES (X-ray Absorption Near Edge Structure) spectroscopy experiments were carried out in order to determine the chemical speciation of these elements in our samples.

  6. Micro and bulk analysis of prostate tissues classified as hyperplasia

    Science.gov (United States)

    Kwiatek, W. M.; Banaś, A.; Banaś, K.; Cinque, G.; Dyduch, G.; Falkenberg, G.; Kisiel, A.; Marcelli, A.; Podgórczyk, M.

    2007-07-01

    BPH (Benign Prostatic Hyperplasia) is the most common benign neoplasm (non cancerous enlargement of the prostate gland), whose prevalence increases with age. The gland, when increased in size, exerts pressure on the urethra, causing obstruction to urine flow. The latter may result in severe urinary tract and kidney conditions. In this work prostate samples from patients diagnosed with BPH were analyzed using synchrotron radiation. Micro-analysis of the hyperplastic samples was carried out on the L-beam line at HASYLAB, DESY (Germany), while bulk analysis on selected samples was performed at the DRX2 beamline at LNF, Frascati (Italy). Microanalysis with a mono-energetic beam 15 μm in diameter confirmed that concentrations of certain elements, such as S, Mn, Cu, Fe and Zn, are good indicators of pathological disorders in prostate tissue that may be considered effective tracers of developing compliant. The concentrations of Mn, Cu, Fe and Zn are higher in hyperplastic tissues, as compared to normal ones, while for sulphur the opposite is observed. Additionally, Fe and S K-edge XANES (X-ray Absorption Near Edge Structure) spectroscopy experiments were carried out in order to determine the chemical speciation of these elements in our samples.

  7. Towards accounting for dissolved iron speciation in global ocean models

    Directory of Open Access Journals (Sweden)

    A. Tagliabue

    2011-10-01

    Full Text Available The trace metal iron (Fe is now routinely included in state-of-the-art ocean general circulation and biogeochemistry models (OGCBMs because of its key role as a limiting nutrient in regions of the world ocean important for carbon cycling and air-sea CO2 exchange. However, the complexities of the seawater Fe cycle, which impact its speciation and bioavailability, are simplified in such OGCBMs due to gaps in understanding and to avoid high computational costs. In a similar fashion to inorganic carbon speciation, we outline a means by which the complex speciation of Fe can be included in global OGCBMs in a reasonably cost-effective manner. We construct an Fe speciation model based on hypothesised relationships between rate constants and environmental variables (temperature, light, oxygen, pH, salinity and assumptions regarding the binding strengths of Fe complexing organic ligands and test hypotheses regarding their distributions. As a result, we find that the global distribution of different Fe species is tightly controlled by spatio-temporal environmental variability and the distribution of Fe binding ligands. Impacts on bioavailable Fe are highly sensitive to assumptions regarding which Fe species are bioavailable and how those species vary in space and time. When forced by representations of future ocean circulation and climate we find large changes to the speciation of Fe governed by pH mediated changes to redox kinetics. We speculate that these changes may exert selective pressure on phytoplankton Fe uptake strategies in the future ocean. In future work, more information on the sources and sinks of ocean Fe ligands, their bioavailability, the cycling of colloidal Fe species and kinetics of Fe-surface coordination reactions would be invaluable. We hope our modeling approach can provide a means by which new observations of Fe speciation can be tested against hypotheses of the processes present in governing the ocean Fe cycle in an

  8. Toughness of Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Shantanu V. Madge

    2015-07-01

    Full Text Available Bulk metallic glasses (BMGs have desirable properties like high strength and low modulus, but their toughness can show much variation, depending on the kind of test as well as alloy chemistry. This article reviews the type of toughness tests commonly performed and the factors influencing the data obtained. It appears that even the less-tough metallic glasses are tougher than oxide glasses. The current theories describing the links between toughness and material parameters, including elastic constants and alloy chemistry (ordering in the glass, are discussed. Based on the current literature, a few important issues for further work are identified.

  9. Ecological Speciation and the Intertidal Snail Littorina saxatilis

    Directory of Open Access Journals (Sweden)

    Juan Galindo

    2014-01-01

    Full Text Available In recent decades biologists studying speciation have come to consider that the process does not necessarily require the presence of a geographical barrier. Rather, it now seems to be possible for reproductive barriers to evolve within what was hitherto a single ‘‘species.’’ The intertidal snail Littorina saxatilis has been the focus of a considerable amount of work in this context, and it is now thought of as a good case study of ‘‘ecological speciation.’’ We review some of this work and briefly consider prospects for future developments.

  10. Speciation of phosphorus in the continental shelf sediments in the Eastern Arabian Sea

    Science.gov (United States)

    Acharya, Shiba Shankar; Panigrahi, Mruganka Kumar; Kurian, John; Gupta, Anil Kumar; Tripathy, Subhasish

    2016-03-01

    The distributions of various forms of phosphorus (P) and their relation with sediment geochemistry in two core sediments near Karwar and Mangalore offshore have been studied through the modified SEDEX procedure (Ruttenberg et al., 2009) and bulk chemical analysis. The present study provides the first quantitative analysis of complete phosphorus speciation in the core sediments of the Eastern Arabian shelf. The chemical index of alteration (CIA), chemical Index of Weathering (CIW) and Al-Ti-Zr ternary diagram suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, despite the intense orographic rainfall in the source area. Due to the presence of same source rock and identical oxic depositional environment, the studied sediments show the same range of variation of total phosphorus (24 to 83 μmol/g) with a down-depth depleting trend. Organic bound P and detrital P are the two major chemical forms followed by iron-bound P, exchangeable/loosely bound P and authigenic P. The authigenic P content in the sediments near Mangalore coast varies linearly with calcium (r=0.88) unlike that of Karwar coast. The different reactive-phosphorus pools exhibit identical depleting trend with depth. This indicates that the phosphorus released from the organic matter and Fe bound fractions are prevented from precipitating as authigenic phosphates in the deeper parts of the sediment column. The low concentration of total P, dominance of detrital non-reactive fraction of P and inhibition of formation of authigenic phosphate result in the absence of active phosphatization in the Eastern Arabian Shelf in the studied region. High sedimentation rate (35-58 cm/kyr) and absence of winnowing effect appear to be the dominant factor controlling the P-speciation in the studied sediments.

  11. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger

    Energy Technology Data Exchange (ETDEWEB)

    Déjeant, Adrien, E-mail: adrien.dejeant@normalesup.org [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Paris Diderot — Paris VII, 5 rue Thomas Mann, 75013 Paris (France); Galoisy, Laurence [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Roy, Régis [AREVA Mines — Geoscience Department, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France); Calas, Georges; Boekhout, Flora [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Phrommavanh, Vannapha; Descostes, Michael [AREVA Mines — R& D Department, BAL 0414C-2, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France)

    2016-03-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam — Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. - Highlights: • The evolution of U distribution and speciation in mill tailings is investigated. • High resolution satellite images provide useful information on tailings evolution. • U and many other elements are enriched in a sulfate-rich duricrust. • Formation of

  12. Simultaneous Speciation of Arsenic, Selenium, and Chromium by HPLC-ICP-MS

    Science.gov (United States)

    Wolf, Ruth E.; Morman, Suzette A.; Morrison, Jean M.; Lamothe, Paul J.

    2008-01-01

    An adaptation of an analytical method developed for chromium speciation has been utilized for the simultaneous determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) species using high performance liquid chromatography (HPLC) separation with ICP-MS detection. Reduction of interferences for the determination of As, Se, and Cr by ICP-MS is a major consideration for this method. Toward this end, a Dynamic Reaction Cell (DRC) ICP-MS system was used to detect the species eluted from the chromatographic column. A variety of reaction cell gases and conditions may be utilized, and the advantages and limitations of the gases tested to date will be presented and discussed. The separation and detection of the As, Se, and Cr species of interest can be achieved using the same chromatographic conditions in less than 2 minutes by complexing the Cr(III) with EDTA prior to injection on the HPLC column. Practical aspects of simultaneous speciation analysis will be presented and discussed, including issues with HPLC sample vial contamination, standard and sample contamination, species stability, and considerations regarding sample collection and preservation methods. The results of testing to determine the method's robustness to common concomitant element and anion effects will also be discussed. Finally, results will be presented using the method for the analysis of a variety of environmental and geological samples including waters, soil leachates and simulated bio-fluid leachates.

  13. Gap-related trapped magnetic flux dependence between single and combined bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z., E-mail: zgdeng@gmail.co [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan); Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Uetake, T.; Izumi, M. [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan)

    2011-05-15

    Highlights: {yields} Rectangular YBCO bulks to realize a compact combination. {yields} The gap effect was added to consider in the trapped flux density mapping. {yields} The trapped-flux dependence between single and combined bulks is gap related. {yields} It is possible to estimate the total magnetic flux of bulk combinations. - Abstract: Aiming at examining the trapped-flux dependence between single and combined bulk superconductors for field-pole applications, three rectangular Y{sub 1.65}Ba{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) bulks with a possibly compact combination were employed to investigate the trapped-flux characteristics of single and combined bulks with a field-cooling magnetization (FCM) method. A gap-related dependence was found between them. At lower gaps of 1 mm and 5 mm, the peak trapped fields and total magnetic flux of combined bulks are both smaller than the additive values of each single bulk, which can be ascribed to the demagnetization influences of the field around the bulk generated by the adjacent ones. While, at larger gaps like 10 mm, the situation becomes reversed. The combined bulks can attain bigger peak trapped fields as well as total magnetic flux, which indicates that the magnetic field by the bulk combination can reach higher gaps, thanks to the bigger magnetic energy compared with the single bulk. The presented results show that, on one hand, it is possible to estimate the total trapped magnetic flux of combined bulks by an approximate additive method of each single bulk while considering a demagnetization factor; on the other hand, it also means that the performance of combined bulks will be superior to the addition of each single bulk at larger gaps, thus preferable for large-scaled magnet applications.

  14. Sequential injection methodology for carbon speciation in bathing waters.

    Science.gov (United States)

    Santos, Inês C; Mesquita, Raquel B R; Machado, Ana; Bordalo, Adriano A; Rangel, António O S S

    2013-05-17

    A sequential injection method (SIA) for carbon speciation in inland bathing waters was developed comprising, in a single manifold, the determination of dissolved inorganic carbon (DIC), free dissolved carbon dioxide (CO2), total carbon (TC), dissolved organic carbon and alkalinity. The determination of DIC, CO2 and TC was based on colour change of bromothymol blue (660 nm) after CO2 diffusion through a hydrophobic membrane placed in a gas diffusion unit (GDU). For the DIC determination, an in-line acidification prior to the GDU was performed and, for the TC determination, an in-line UV photo-oxidation of the sample prior to GDU ensured the conversion of all carbon forms into CO2. Dissolved organic carbon (DOC) was determined by subtracting the obtained DIC value from the TC obtained value. The determination of alkalinity was based on the spectrophotometric measurement of bromocresol green colour change (611 nm) after reaction with acetic acid. The developed SIA method enabled the determination of DIC (0.24-3.5 mg C L(-1)), CO2 (1.0-10 mg C L(-1)), TC (0.50-4.0 mg C L(-1)) and alkalinity (1.2-4.7 mg C L(-1) and 4.7-19 mg C L(-1)) with limits of detection of: 9.5 μg C L(-1), 20 μg C L(-1), 0.21 mg C L(-1), 0.32 mg C L(-1), respectively. The SIA system was effectively applied to inland bathing waters and the results showed good agreement with reference procedures.

  15. Analysis and Speciation of Lanthanoides by ICP-MS

    Science.gov (United States)

    Telgmann, Lena; Lindner, Uwe; Lingott, Jana; Jakubowski, Norbert

    2016-11-01

    Inductively coupled plasma mass spectrometry (ICP-MS) is based on formation of positively charged atomic ions in a high-frequency inductively coupled Argon plasma at atmospheric pressure. The ions are extracted and transferred from the plasma source into a mass analyzer operated at high vacuum via an interface equipped with a sampling and a skimmer cone. The ions are separated in the mass analyzer according to their charge to mass ratio. The ions are converted at a conversion dynode and are detected by use of a secondary electron multiplier or a Faraday cup. From an analytical point of view, ICP-MS is a well-established method for multi-elemental analysis in particular for elements at trace- and ultra-trace levels. Furthermore, methods based on ICP-MS offer simple quantification concepts, for which usually (liquid) standards are applied, low matrix effects compared to other conventional analytical techniques, and relative limits of detection (LODs) in the low pg g-1 range and absolute LODs down to the attomol range. For these applications, ICP-MS excels by a high sensitivity which is independent of the molecular structure and a wide linear dynamic range. It has found acceptance in various application areas and during the last decade ICP-MS is also more and more applied for detection of rare earth elements particularly in the life sciences. Due to the fact that all molecules introduced into the high temperature of the plasma in the ion source were completely dissociated and broken down into atoms, which are subsequently ionized, all elemental species information is completely lost. However, if the different species are separated before they enter the plasma by using adequate fractionation or separation techniques, then ICP-MS can be used as a very sensitive element-specific detector. We will discuss this feature of ICP-MS in this chapter in more detail at hand of the speciation of gadolinium-containing contrast agents.

  16. Analysis of physical demands during bulk bag closing and sealing.

    Science.gov (United States)

    Nasarwanji, Mahiyar F; Reardon, Leanna M; Heberger, John R; Dempsey, Patrick G

    2016-05-01

    Several tools are sold and recommended for closing and sealing flexible intermediate bulk containers (bulk bags) which are used to transport product that has been mined and processed. However, there is limited information on the risks, physical demands, or the benefits of using one tool over another. The purpose of this study was to evaluate the physical demands involved with two closing methods and several sealing tools in order to provide recommendations for selecting tools to reduce exposure to risk factors for work-related musculoskeletal disorders. In this study, twelve participants completed bag closing and sealing tasks using two different closing methods and eight sealing tools on two types of bulk bags. Physical demands and performance were evaluated using muscle activity, perceived exertion, subjective ratings of use, and time. Results indicate that using the "flowering" method to close bags required on average 32% less muscle activity, 30% less perceived exertion, 42% less time, and was preferred by participants compared to using the "snaking" method. For sealing, there was no single method significantly better across all measures; however, using a pneumatic cable tie gun consistently had the lowest muscle activity and perceived exertion ratings. The pneumatic cable tie gun did require approximately 33% more time to seal the bag compared to methods without a tool, but the amount of time to seal the bag was comparable to using other tools. Further, sealing a spout bulk bag required on average 13% less muscle activity, 18% less perceived exertion, 35% less time, and was preferred by participants compared to sealing a duffle bulk bag. The current results suggest that closing the spout bag using the flowering method and sealing the bag using the pneumatic cable tie gun that is installed with a tool balancer is ergonomically advantageous. Our findings can help organizations select methods and tools that pose the lowest physical demands when closing and

  17. 复合胶本体聚合法增韧ABS合成及结构与性能%Synthesis,structure and properties of ABS toughened by composite rubber via bulk polymerization method

    Institute of Scientific and Technical Information of China (English)

    于志省; 李杨; 杨娟; 杨力; 郭曦; 张春庆; 王玉荣

    2011-01-01

    The poly(acrylonitrile-butadiene-styrene)(ABS) resins were synthesized via bulk polymerization method using nickel catalyzed high-cis polybutadiene rubber(Ni-9004),lithium catalyzed low-cis polybutadiene rubber(Li-700A) and their composite rubbers as modifiers.The influences of reaction time and content of composite rubber on the polymerization reaction,grafting parameters and microstructures of ABS were investigated.And the morphologies and mechanical properties of resins under different incorporation ratio of composite rubbers were also researched.It is shown that the grafting degree of Ni-9004 gradually increases and its grafting efficiency and volume fraction of rubber phase gradually decrease with the reaction time.Besides,an obvious phase inversion occurs in the polymerization process and the final ABS resin presents a typical ″core-shell″ structure.And its morphology can be distinctly improved when combined with Li-700A.Furthermore,the lower amount of composite rubber is beneficial to grafting and occlusion,which shows a positive reinforcement value;an augmented particle size and a negative value are obtained while composite rubber amount increases.Performance measurements show that the toughening effect of Li-700A can be significantly enhanced by incorporating Ni-9004.When its incorporation content reaches 75%,the notched Izod impact strength of ABS resin is improved by at least 150%,while there is no loss of the tensile strength.%以镍系高顺式聚丁二烯橡胶(Ni-9004)、锂系低顺式聚丁二烯橡胶(Li-700A)及二者的复合胶做增韧改性剂,用本体聚合法合成了聚(丙烯腈-丁二烯-苯乙烯)(ABS)树脂,考察了聚合时间、复合胶用量对ABS聚合反应、接枝参数和微观形态的影响,并对复合胶不同配比下树脂形态及性能进行了研究.结果表明:随聚合时间的延长,Ni-9004的接枝率增大,而接枝效率和橡胶相体积分数均有所降低;聚合中

  18. Effect of air drying on speciation of heavy metals in flooded rice paddies

    Institute of Scientific and Technical Information of China (English)

    Bao Wang; Biao Huang; Yan Bing Qi; Wen You Hu; Wei Xia Sun

    2012-01-01

    Flooded soil samples were collected in the typical area of the Yangtze Delta Region; fractions of heavy metals in flooded and air dried samples were measured with BCR sequential extraction method and atomic absorption spectrometry.In flooded soils,fractions of heavy metals increased in the order of acid soluble < oxidizable < reducible < residual.The acid soluble and reducible fractions significantly decreased but residual fraction significantly increased when the samples were air dried.The data obtained from air dried soil samples could not accurately represent the speciation of heavy metals in flooded field conditions.

  19. Handling of bulk solids theory and practice

    CERN Document Server

    Shamlou, P A

    1990-01-01

    Handling of Bulk Solids provides a comprehensive discussion of the field of solids flow and handling in the process industries. Presentation of the subject follows classical lines of separate discussions for each topic, so each chapter is self-contained and can be read on its own. Topics discussed include bulk solids flow and handling properties; pressure profiles in bulk solids storage vessels; the design of storage silos for reliable discharge of bulk materials; gravity flow of particulate materials from storage vessels; pneumatic transportation of bulk solids; and the hazards of solid-mater

  20. Speciation of four selenium compounds using high performance liquid chromatography with on-line detection by inductively coupled plasma mass spectrometry or flame atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Pedersen, Gitte Alsing; Larsen, Erik Huusfeldt

    1997-01-01

    spectrometry (ICP-MS). The signal-to-noise ratio of the FAAS detector was optimized using a hydrogen-argon entrained-air flame and a slotted-tube atom trap (STAT) in the flame. The limit of detection (3 sigma) achieved by the HPLC-FAAS system was 1 mg L-1 of selenium (100 mu L injections) for each of the four......An analytical method for the speciation of selenomethionine, selenocystine, selenite and selenate by high performance liquid chromatography (HPLC) with atomic spectrometric detection is presented. An organic polymeric strong anion exchange column was used as the stationary phase in combination...... of 1300 W. The limit of detection achieved under these conditions was 1 mu g L-1 (100 mu L injections). The HPLC-ICP-MS system was used for selenium speciation of selenite and selenate in aqueous solutions during a BCR certification exercise and for selenium speciation in the certified reference material...

  1. Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries

    DEFF Research Database (Denmark)

    Hansen, Claus; Schmidt, Bjørn; Larsen, Erik Huusfeldt;

    2011-01-01

    In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb’s oxidation state. The most commonly applied chromatographic methods used for this redox speciation...... analysis do, however, often show a low chromatographic Sb recovery when samples of environmental or biological origin are analysed. In this study we explored basal chemistry of antimony and found that formation of macromolecules, presumably oligomeric and polymeric Sb(V) species, is the primary cause...... of low chromatographic recoveries. A combination of HPLC-ICP-MS, AFFF-ICP-MS and spinfiltration was applied for analysis of model compounds and biological samples. Quantitative chromatographic Sb redox speciation analysis was possible by acidic hydrolysis of the antimony polymers prior to analysis...

  2. A Batch Feeder for Inhomogeneous Bulk Materials

    Science.gov (United States)

    Vislov, I. S.; Kladiev, S. N.; Slobodyan, S. M.; Bogdan, A. M.

    2016-04-01

    The work includes the mechanical analysis of mechanical feeders and batchers that find application in various technological processes and industrial fields. Feeders are usually classified according to their design features into two groups: conveyor-type feeders and non-conveyor feeders. Batchers are used to batch solid bulk materials. Less frequently, they are used for liquids. In terms of a batching method, they are divided into volumetric and weighting batchers. Weighting batchers do not provide for sufficient batching accuracy. Automatic weighting batchers include a mass controlling sensor and systems for automatic material feed and automatic mass discharge control. In terms of operating principle, batchers are divided into gravitational batchers and batchers with forced feed of material using conveyors and pumps. Improved consumption of raw materials, decreased loss of materials, ease of use in automatic control systems of industrial facilities allows increasing the quality of technological processes and improve labor conditions. The batch feeder suggested by the authors is a volumetric batcher that has no comparable counterparts among conveyor-type feeders and allows solving the problem of targeted feeding of bulk material batches increasing reliability and hermeticity of the device.

  3. Plant evolution: pulses of extinction and speciation in gymnosperm diversity.

    Science.gov (United States)

    Davis, Charles C; Schaefer, Hanno

    2011-12-20

    Living gymnosperms represent the survivors of ancient seed plant lineages whose fossil record reaches back 270 million years. Two recent studies find that recent pulses of extinction and speciation have shaped today's gymnosperm diversity, contradicting the widespread assumption that gymnosperms have remained largely unchanged for tens of millions of years.

  4. Capillary electrophoresis application in metal speciation and complexation characterization

    Science.gov (United States)

    Capillary electrophoresis is amenable to the separation of metal ionic species and the characterization of metal-ligand interactions. This book chapter reviews and discusses three representative case studies in applications of CE technology in speciation and reactions of metal with organic molecules...

  5. Electrochemical metal speciation in natural and model polyelectrolyte systems.

    NARCIS (Netherlands)

    Hoop, van den M.A.G.T.

    1994-01-01

    The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules. In chapter

  6. Cytonuclear incompatibility contributes to the early stages of speciation.

    Science.gov (United States)

    Barnard-Kubow, Karen B; So, Nina; Galloway, Laura F

    2016-12-01

    Genetic incompatibility is a hallmark of speciation. Cytonuclear incompatibilities are proposed to be among the first genetic barriers to arise during speciation. Accordingly, reproductive isolation (RI) within species should be heavily influenced by interactions between the organelle and nuclear genomes. However, there are few clear examples of cytonuclear incompatibility within a species. Here, we show substantial postzygotic RI in first-generation hybrids between differentiated populations of an herbaceous plant (up to 92% reduction in fitness). RI was primarily due to germination and survival, with moderate RI for pollen viability. RI for survival was asymmetric and caused by cytonuclear incompatibility, with the strength of incompatibility linearly related to chloroplast genetic distance. This cytonuclear incompatibility may be the result of a rapidly evolving plastid genome. Substantial asymmetric RI was also found for germination, but was not associated with cytonuclear incompatibility, indicating endosperm or maternal-zygote incompatibilities. These results demonstrate that cytonuclear incompatibility contributes to RI within species, suggesting that initial rates of speciation could be influenced by rates of organelle evolution. However, other genetic incompatibilities are equally important, indicating that even at early stages, speciation can be a complex process involving multiple genes and incompatibilities.

  7. Metacommunity speciation models and their implications for diversification theory.

    Science.gov (United States)

    Hubert, Nicolas; Calcagno, Vincent; Etienne, Rampal S; Mouquet, Nicolas

    2015-08-01

    The emergence of new frameworks combining evolutionary and ecological dynamics in communities opens new perspectives on the study of speciation. By acknowledging the relative contribution of local and regional dynamics in shaping the complexity of ecological communities, metacommunity theory sheds a new light on the mechanisms underlying the emergence of species. Three integrative frameworks have been proposed, involving neutral dynamics, niche theory, and life history trade-offs respectively. Here, we review these frameworks of metacommunity theory to emphasise that: (1) studies on speciation and community ecology have converged towards similar general principles by acknowledging the central role of dispersal in metacommunities dynamics, (2) considering the conditions of emergence and maintenance of new species in communities has given rise to new models of speciation embedded in the metacommunity theory, (3) studies of diversification have shifted from relating phylogenetic patterns to landscapes spatial and ecological characteristics towards integrative approaches that explicitly consider speciation in a mechanistic ecological framework. We highlight several challenges, in particular the need for a better integration of the eco-evolutionary consequences of dispersal and the need to increase our understanding on the relative rates of evolutionary and ecological changes in communities.

  8. Underappreciated Consequences of Phenotypic Plasticity for Ecological Speciation

    Directory of Open Access Journals (Sweden)

    Benjamin M. Fitzpatrick

    2012-01-01

    Full Text Available Phenotypic plasticity was once seen primarily as a constraint on adaptive evolution or merely a nuisance by geneticists. However, some biologists promote plasticity as a source of novelty and a factor in evolution on par with mutation, drift, gene flow, and selection. These claims are controversial and largely untested, but progress has been made on more modest questions about effects of plasticity on local adaptation (the first component of ecological speciation. Adaptive phenotypic plasticity can be a buffer against divergent selection. It can also facilitate colonization of new niches and rapid divergent evolution. The influence of non-adaptive plasticity has been underappreciated. Non-adaptive plasticity, too can interact with selection to promote or inhibit genetic differentiation. Finally, phenotypic plasticity of reproductive characters might directly influence evolution of reproductive isolation (the second component of ecological speciation. Plasticity can cause assortative mating, but its influence on gene flow ultimately depends on maintenance of environmental similarity between parents and offspring. Examples of plasticity influencing mating and habitat choice suggest that this, too, might be an underappreciated factor in speciation. Plasticity is an important consideration for studies of speciation in nature, and this topic promises fertile ground for integrating developmental biology with ecology and evolution.

  9. Latitude, elevational climatic zonation and speciation in New World vertebrates.

    Science.gov (United States)

    Cadena, Carlos Daniel; Kozak, Kenneth H; Gómez, Juan Pablo; Parra, Juan Luis; McCain, Christy M; Bowie, Rauri C K; Carnaval, Ana C; Moritz, Craig; Rahbek, Carsten; Roberts, Trina E; Sanders, Nathan J; Schneider, Christopher J; VanDerWal, Jeremy; Zamudio, Kelly R; Graham, Catherine H

    2012-01-07

    Many biodiversity hotspots are located in montane regions, especially in the tropics. A possible explanation for this pattern is that the narrow thermal tolerances of tropical species and greater climatic stratification of tropical mountains create more opportunities for climate-associated parapatric or allopatric speciation in the tropics relative to the temperate zone. However, it is unclear whether a general relationship exists among latitude, climatic zonation and the ecology of speciation. Recent taxon-specific studies obtained different results regarding the role of climate in speciation in tropical versus temperate areas. Here, we quantify overlap in the climatic distributions of 93 pairs of sister species of mammals, birds, amphibians and reptiles restricted to either the New World tropics or to the Northern temperate zone. We show that elevational ranges of tropical- and temperate-zone species do not differ from one another, yet the temperature range experienced by species in the temperate zone is greater than for those in the tropics. Moreover, tropical sister species tend to exhibit greater similarity in their climatic distributions than temperate sister species. This pattern suggests that evolutionary conservatism in the thermal niches of tropical taxa, coupled with the greater thermal zonation of tropical mountains, may result in increased opportunities for allopatric isolation, speciation and the accumulation of species in tropical montane regions. Our study exemplifies the power of combining phylogenetic and spatial datasets of global climatic variation to explore evolutionary (rather than purely ecological) explanations for the high biodiversity of tropical montane regions.

  10. Stripping chronopotentiometry for metal ion speciation analysis at a microelectrode

    NARCIS (Netherlands)

    Leeuwen, van H.P.; Town, R.

    2002-01-01

    The features of metal ion speciation determination by stripping chronopotentiometry (SCP) at a microelectrode are examined and compared with those of DP-SV. SCP measurements are essentially of a steady-state nature under experimentally achievable conditions and correspond to practically complete dep

  11. Species and speciation in the Hebeloma crustuliniforme complex

    NARCIS (Netherlands)

    Aanen, D.K.

    1999-01-01

    This thesis deals with species delimitation and speciation in the ectomycorrhizal Hebeloma crustuliniforme complex. The species concept traditionally used in this complex is based on morphology of basidiocarps. However, species delimitation has been controversial. One of the best known names is H. c

  12. Behavioural isolation may facilitate homoploid hybrid speciation in cichlid fish

    NARCIS (Netherlands)

    Selz, O. M.; Thommen, R.; Maan, M. E.; Seehausen, O.

    2014-01-01

    Hybrid speciation is constrained by the homogenizing effects of gene flow from the parental species. In the absence of post-mating isolation due to structural changes in the genome, or temporal or spatial premating isolation, another form of reproductive isolation would be needed for homoploid hybri

  13. A recombination suppressor contributes to ecological speciation in OSTRINIA moths.

    Science.gov (United States)

    Wadsworth, C B; Li, X; Dopman, E B

    2015-06-01

    Despite unparalleled access to species' genomes in our post-genomic age, we often lack adequate biological explanations for a major hallmark of the speciation process-genetic divergence. In the presence of gene flow, chromosomal rearrangements such as inversions are thought to promote divergence and facilitate speciation by suppressing recombination. Using a combination of genetic crosses, phenotyping of a trait underlying ecological isolation, and population genetic analysis of wild populations, we set out to determine whether evidence supports a role for recombination suppressors during speciation between the Z and E strains of European corn borer moth (Ostrinia nubilalis). Our results are consistent with the presence of an inversion that has contributed to accumulation of ecologically adaptive alleles and genetic differentiation across roughly 20% of the Ostrinia sex chromosome (~4 Mb). Patterns in Ostrinia suggest that chromosomal divergence may involve two separate phases-one driving its transient origin through local adaptation and one determining its stable persistence through differential introgression. As the evolutionary rate of rearrangements in lepidopteran genomes appears to be one of the fastest among eukaryotes, structural mutations may have had a disproportionate role during adaptive divergence and speciation in Ostrinia and in other moths and butterflies.

  14. Nanofluidics, from bulk to interfaces.

    Science.gov (United States)

    Bocquet, Lydéric; Charlaix, Elisabeth

    2010-03-01

    Nanofluidics has emerged recently in the footsteps of microfluidics, following the quest for scale reduction inherent to nanotechnologies. By definition, nanofluidics explores transport phenomena of fluids at nanometer scales. Why is the nanometer scale specific? What fluid properties are probed at nanometric scales? In other words, why does 'nanofluidics' deserve its own brand name? In this critical review, we will explore the vast manifold of length scales emerging for fluid behavior at the nanoscale, as well as the associated mechanisms and corresponding applications. We will in particular explore the interplay between bulk and interface phenomena. The limit of validity of the continuum approaches will be discussed, as well as the numerous surface induced effects occurring at these scales, from hydrodynamic slippage to the various electro-kinetic phenomena originating from the couplings between hydrodynamics and electrostatics. An enlightening analogy between ion transport in nanochannels and transport in doped semi-conductors will be discussed (156 references).

  15. New fermions in the bulk

    CERN Document Server

    de Brito, K P S

    2016-01-01

    Spinor fields on 5-dimensional Lorentzian manifolds are classified, according to the geometric Fierz identities that involve their bilinear covariants. Based upon this classification that generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are, hence, found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density, through the truncated exterior bundle. In order to accomplish a realisation of these new spinors, a Killing vector field is constructed on the horizon of 5-dimensional Kerr black holes. This Killing vector field is shown to reach the time-like Killing vector field at the spatial infinity, through a current 1-form density, constructed with the derived new spinor fields. The current density is, moreover, expressed as the f\\"unfbein components, assuming a condensed for...

  16. New fermions in the bulk

    Science.gov (United States)

    de Brito, K. P. S.; da Rocha, Roldão

    2016-10-01

    The spinor fields on 5-dimensional Lorentzian manifolds are classified according to the geometric Fierz identities, which involve their bilinear covariants. Based upon this classification, which generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are hence found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density through the truncated exterior bundle. In order to accomplish the realisation of these new spinors, a Killing vector field is constructed on the horizon of a 5-dimensional Kerr black hole. This Killing vector field is shown to reach the time-like Killing vector field at spatial infinity through a current 1-form density, constructed with the new derived spinor fields. The current density is, moreover, expressed as the fünfbein component, assuming a condensed form.

  17. Sensitive redox speciation of neptunium by CE-ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Stoebener, Nils; Amayri, Samer; Gehl, Aaron; Kaplan, Ugras; Malecha, Kurtis; Reich, Tobias [Johannes Gutenberg-Universitaet Mainz, Institute of Nuclear Chemistry, Mainz (Germany)

    2012-11-15

    Capillary electrophoresis (CE) was used to separate the neptunium oxidation states Np(IV) and Np(V), which are the only oxidation states of Np that are stable under environmental conditions. The CE setup was coupled to an inductively coupled plasma mass spectrometer (Agilent 7500ce) using a Mira Mist CE nebulizer and a Scott-type spray chamber. The combination of the separation capacity of CE with the detection sensitivity of inductively coupled plasma mass spectrometry (ICP-MS) allows identification and quantification of Np(IV) and Np(V) at the trace levels expected in the far field of a nuclear waste repository. Limits of detection of 1 x 10{sup -9} and 5 x 10{sup -10} mol L{sup -1} for Np(IV) and Np(V), respectively, were achieved, with a linear range from 10{sup -9} to 10{sup -6} mol L{sup -1}. The method was applied to study the redox speciation of the Np remaining in solution after interaction of 5 x 10{sup -7} mol L{sup -1} Np(V) with Opalinus Clay. Under mildly oxidizing conditions, a Np sorption of 31% was found, with all the Np remaining in solution being Np(V). A second sorption experiment performed in the presence of Fe{sup 2+} led to complete sorption of the Np onto the clay. After desorption with HClO{sub 4}, a mixture of Np(IV) and Np(V) was found in solution by CE-ICP-MS, indicating that some of the sorbed Np had been reduced to Np(IV) by Fe{sup 2+}. (orig.)

  18. Evidence for progenitor–derivative speciation in sexually deceptive orchids

    Science.gov (United States)

    Schlüter, Philipp M.; Ruas, Paulo M.; Kohl, Gudrun; Ruas, Claudete F.; Stuessy, Tod F.; Paulus, Hannes F.

    2011-01-01

    Background and Aims Sexually deceptive orchids of the genus Ophrys use mimicry of pollinator females to attract specific pollinators. Pollinator shifts may drive speciation in Ophrys, since novel pollinators may in principle act as isolating factors immediately. It is thus possible that evolution of novel species occurs rapidly and with a progenitor–derivative pattern. The aims of this study are to compare genetic structure and diversity among widespread and geographically restricted Ophrys taxa, to test whether genetic structure is associated with specific pollinators, and to investigate whether any widespread species may have acted as a progenitor for the evolution of more restricted taxa. Methods Genetic differentiation and diversity were investigated in O. leucadica and O. cinereophila, the two taxa of the Ophrys fusca sensu lato complex widespread in the Aegean, and three geographically restricted taxa from Rhodes, O. attaviria, O. parvula and O. persephonae, all differing in their specific pollinators. This was done using amplified fragment length polymorphism (AFLP) DNA fingerprinting, and sequencing of the low-copy nuclear gene LEAFY (LFY). Key Results All taxa were found to be separate genetic entities, with O. leucadica forming two geographic groups from the west and east of the Aegean. Genetic structure was significantly shaped by pollinators and geography, and comparison of sequence and AFLP data revealed ancestral polymorphisms shared among several taxa. Among the sampled taxa, O. leucadica harbours the greatest genetic differentiation and geographic structure, and the highest genetic diversity. Part of the genome of O. parvula, endemic to Rhodes, may be derived from O. leucadica. Conclusions Pollinators probably influence the genetic structure of the investigated Ophrys species. The genetic pattern identified is consistent with O. leucadica being the oldest of the sampled taxa, making O. leucadica a candidate progenitor species from which more

  19. Layer speciation and electronic structure investigation of freestanding hexagonal boron nitride nanosheets

    Science.gov (United States)

    WangEqual Contribution To This Work., Jian; Wang, Zhiqiang; Cho, Hyunjin; Kim, Myung Jong; Sham, T. K.; Sun, Xuhui

    2015-01-01

    Chemical imaging, thickness mapping, layer speciation and polarization dependence have been performed on single and multilayered (up to three layers and trilayered nanosheets overlapping to form 6 and 9 layers) hexagonal boron nitride (hBN) nanosheets by scanning transmission X-ray microscopy. Spatially-resolved XANES directly from freestanding regions of different layers has been extracted and compared with sample normal and 30° tilted configurations. Notably a double feature σ* excitonic state and a stable high energy σ* state were observed at the boron site in addition to the intense π* excitonic state. The boron projected σ* DOS, especially the first σ* exciton, is sensitive to surface modification, particularly in the single layered hBN nanosheet which shows more significant detectable contaminants and defects such as tri-coordinated boron/nitrogen oxide. The nitrogen site has shown very weak or no excitonic character. The distinct excitonic effect on boron and nitrogen was interpreted to the partly ionic state of hBN. Bulk XANES of hBN nanosheets was also measured to confirm the spectro-microscopic STXM result. Finally, the unoccupied electronic structures of hBN and graphene were compared.Chemical imaging, thickness mapping, layer speciation and polarization dependence have been performed on single and multilayered (up to three layers and trilayered nanosheets overlapping to form 6 and 9 layers) hexagonal boron nitride (hBN) nanosheets by scanning transmission X-ray microscopy. Spatially-resolved XANES directly from freestanding regions of different layers has been extracted and compared with sample normal and 30° tilted configurations. Notably a double feature σ* excitonic state and a stable high energy σ* state were observed at the boron site in addition to the intense π* excitonic state. The boron projected σ* DOS, especially the first σ* exciton, is sensitive to surface modification, particularly in the single layered hBN nanosheet which

  20. Host shift and speciation in a coral-feeding nudibranch

    Science.gov (United States)

    Faucci, Anuschka; Toonen, Robert J; Hadfield, Michael G

    2006-01-01

    While the role of host preference in ecological speciation has been investigated extensively in terrestrial systems, very little is known in marine environments. Host preference combined with mate choice on the preferred host can lead to population subdivision and adaptation leading to host shifts. We use a phylogenetic approach based on two mitochondrial genetic markers to disentangle the taxonomic status and to investigate the role of host specificity in the speciation of the nudibranch genus Phestilla (Gastropoda, Opisthobranchia) from Guam, Palau and Hawaii. Species of the genus Phestilla complete their life cycle almost entirely on their specific host coral (species of Porites, Goniopora and Tubastrea). They reproduce on thei