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11.
Problems in the use of x-ray spectrometry for the fast multi-element analysis of environmental samples such as aerosols collected on filters arise from absorption of the fluorescence intensity in the filter and in the collected matter. A procedure is described for the determination of the elements sulphur to calcium in aerosols collected on Whatman 41 filters. Two methods are compared for deconvolution of the spectra. These are based on counting in fixed energy channels or on non-linear least-squares analysis. Corrections for absorption effects have been calculated. Calibration is done with thin film standard deposits. The accuracy of the method is better than 15%. Difficulties in ascertaining the chlorine content of the filter are discussed. The evaporation of the chlorine fraction from the filter was studied in detail. 相似文献
12.
Eva C. Sonnenschein Marc Stierhof Stephan Goralczyk Floriane M. Vabre Leonie Pellissier Kine Østnes Hanssen Mercedes de la Cruz Caridad Díaz Peter de Witte Daniëlle Copmans Jeanette Hammer Andersen Espen Hansen Venke Kristoffersen José R. Tormo Rainer Ebel Bruce F. Milne Hai Deng Lone Gram Jioji N. Tabudravu 《Tetrahedron》2017,73(18):2633-2637
A new siderophore containing a 4,5-dihydroimidazole moiety was isolated from Pseudoalteromonas piscicida S2040 together with myxochelins A and B, alteramide A and its cycloaddition product, and bromo- and dibromoalterochromides. The structure of pseudochelin A was established by spectroscopic techniques including 2D NMR and MS/MS fragmentation data. In bioassays selected fractions of the crude extract of S2040 inhibited the opportunistic pathogen Pseudomonas aeruginosa. Pseudochelin A displayed siderophore activity in the chrome azurol S assay at concentrations higher than 50 μM, and showed weak activity against the fungus Aspergillus fumigatus, but did not display antibacterial, anti-inflammatory or anticonvulsant activity. 相似文献
13.
Friis Helmer André Pedersen Janne Jettestuen Espen Helland Johan Olav Prodanović Maša 《Transport in Porous Media》2019,128(1):123-151
Transport in Porous Media - Multiphase flow simulations on imaged porous rock structures require numerical methods that are accurate and robust when applied on complex geometries. A key element in... 相似文献
14.
Fred Espen Benth 《Applied Mathematical Finance》2018,25(1):36-65
The recent introduction of wind power futures written on the German wind power production index has brought with it new interesting challenges in terms of modelling and pricing. Some particularities of this product are the strong seasonal component embedded in the underlying, the fact that the wind index is bounded from both above and below and also that the futures are settled against a synthetically generated spot index. Here, we consider the non-Gaussian Ornstein–Uhlenbeck type processes proposed by Barndorff-Nielsen and Shephard in the context of modelling the wind power production index. We discuss the properties of the model and estimation of the model parameters. Further, the model allows for an analytical formula for pricing wind power futures. We provide an empirical study, where the model is calibrated to 37 years of German wind power production index that is synthetically generated assuming a constant level of installed capacity. Also, based on 1 year of observed prices for wind power futures with different delivery periods, we study the market price of risk. Generally, we find a negative risk premium whose magnitude decreases as the length of the delivery period increases. To further demonstrate the benefits of our proposed model, we address the pricing of European options written on wind power futures, which can be achieved through Fourier techniques. 相似文献
15.
W. Van Borm P. Van Espen F. Adams M. Demuynck 《International journal of environmental analytical chemistry》2013,93(2-4):165-182
Abstract A methodology is described for the apportionment of zinc-containing particulate matter sampled in the vicinity of a zinc smelter to their corresponding sources in the factory. Bulk samples of particulate matter from six potential emission sources were analysed by automated electron probe microanalysis (EPMA) in order to characterize the individual particles. Based on a data set of relative peak intensities and with the aid of a binary clustering method, the most important particle classes were identified. They were used as a basis for the development of a set of disjunct identification rules (decision rules), which were able to describe the classes in a unique manner. Applying these rules upon ambient particulate data enabled the estimation of relative contributions of different types of zinc-containing particles. Evidence was found that a large number of particles was modified by a soil component or by gas phase reactions. 相似文献
16.
Dr. Vibe B. Jakobsen Dr. Elzbieta Trzop Dr. Laurence C. Gavin Emiel Dobbelaar Dr. Shalinee Chikara Dr. Xiaxin Ding Dr. Kane Esien Dr. Helge Müller-Bunz Dr. Solveig Felton Dr. Vivien S. Zapf Prof. Eric Collet Prof. Michael A. Carpenter Prof. Grace G. Morgan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13407-13414
Domain wall motion is detected for the first time during the transition to a ferroelastic and spin state ordered phase of a spin crossover complex. Single-crystal X-ray diffraction and resonant ultrasound spectroscopy (RUS) revealed two distinct symmetry-breaking phase transitions in the mononuclear Mn3+ compound [Mn(3,5-diBr-sal2(323))]BPh4, 1. The first at 250 K, involves the space group change Cc→Pc and is thermodynamically continuous, while the second, Pc→P1 at 85 K, is discontinuous and related to spin crossover and spin state ordering. Stress-induced domain wall mobility was interpreted on the basis of a steep increase in acoustic loss immediately below the the Pc-P1 transition 相似文献
17.
Priyanka Michael Espen Hansen Johan Isaksson Jeanette H. Andersen 《Natural product research》2020,34(14):2059-2064
AbstractThe new guanidine alkaloid Dendrobeaniamine A (1) was isolated from the organic extract of the Arctic marine bryozoan Dendrobeania murrayana. The chemical structure of 1 was elucidated by spectroscopic experiments, including 1D and 2D NMR and HRESIMS analysis. Compound 1 is a lipoamino acid, consisting of a C12 fatty acid anchored to the amino acid arginine. The bioactivity of 1 was evaluated using cellular and biochemical assays, but the compound did not show cytotoxic, antimicrobial, anti-inflammatory or antioxidant activities 相似文献
18.
A new zirconium inorganic building brick forming metal organic frameworks with exceptional stability 总被引:3,自引:0,他引:3
Cavka JH Jakobsen S Olsbye U Guillou N Lamberti C Bordiga S Lillerud KP 《Journal of the American Chemical Society》2008,130(42):13850-13851
Porous crystals are strategic materials with industrial applications within petrochemistry, catalysis, gas storage, and selective separation. Their unique properties are based on the molecular-scale porous character. However, a principal limitation of zeolites and similar oxide-based materials is the relatively small size of the pores, typically in the range of medium-sized molecules, limiting their use in pharmaceutical and fine chemical applications. Metal organic frameworks (MOFs) provided a breakthrough in this respect. New MOFs appear at a high and an increasing pace, but the appearances of new, stable inorganic building bricks are rare. Here we present a new zirconium-based inorganic building brick that allows the synthesis of very high surface area MOFs with unprecedented stability. The high stability is based on the combination of strong Zr-O bonds and the ability of the inner Zr6-cluster to rearrange reversibly upon removal or addition of mu3-OH groups, without any changes in the connecting carboxylates. The weak thermal, chemical, and mechanical stability of most MOFs is probably the most important property that limits their use in large scale industrial applications. The Zr-MOFs presented in this work have the toughness needed for industrial applications; decomposition temperature above 500 degrees C and resistance to most chemicals, and they remain crystalline even after exposure to 10 tons/cm2 of external pressure. 相似文献
19.
Bearden IG Beavis D Besliu C Blyakhman Y Budick B Bøggild H Chasman C Christensen CH Christiansen P Cibor J Debbe R Enger E Gaardhøje JJ Hagel K Hansen O Holm A Holme AK Ito H Jakobsen E Jipa A Jørdre JI Jundt F Jørgensen CE Karabowicz R Keutgen T Kim EJ Kozik T Larsen TM Lee JH Lee YK Løvhøiden G Majka Z Makeev A McBreen B Mikelsen M Murray M Natowitz J Nielsen BS Norris J Olchanski K Olness J Ouerdane D Płaneta R Rami F Ristea C Röhrich D Samset BH Sandberg D Sanders SJ Sheetz RA Staszel P 《Physical review letters》2002,88(20):202301
We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the 197Au+197Au reaction at square root[s(NN)] = 200 GeV. For the 5% most central events we obtain dN(ch)/deta/(eta = 0) = 625+/-55 and N(ch)/(-4.7< or =eta < or =4.7) = 4630 +/- 370, i.e., 14% and 21% increases, respectively, relative to square root[s(NN)] = 130 GeV collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy. 相似文献
20.
We compute tensor products of representations of the holomorphic discrete series of a Lie group G, or restrictions to some subgroup G′. A detailed study is done for the case of the conformal group O(4, 2). 相似文献