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81.
Urgast DS Ellingsen DG Berlinger B Eilertsen E Friisk G Skaug V Thomassen Y Beattie JH Kwun IS Feldmann J 《Analytical and bioanalytical chemistry》2012,404(1):89-99
In recent years, bismuth has been promoted as a "green element" and is used as a substitute for the toxic lead in ammunition and other applications. However, the bioavailability and toxicity of bismuth is still not very well described. Following a hunting accident with bismuth-containing shots, a bioavailability study of bismuth from metal pellets inoculated into rat limb muscles was carried out. Bismuth could be found in urine and blood of the animals. Bio-imaging using laser ablation ICP-MS of thin sections of the tissue around the metal implant was carried out to find out more about the distribution of the metal diffusing into the tissue. Two laser ablation systems with different ablation cell designs were compared regarding their analytical performance. Low concentrations of bismuth showing a non-symmetrical pattern were detected in the tissue surrounding the metal implant. This was partly an artefact from cutting the thin sections but also bio-mobilisation of the metals of the implant could be seen. An accumulation of zinc around the implant was interpreted as a marker of inflammation. Challenges regarding sample preparation for laser ablation and bio-imaging of samples of diverse composition became apparent during the analysis. 相似文献
82.
A crystal face growing from solution while exerting a normal force on a confining surface is often observed to develop a growth rim surrounding a hollow core. The interpretation has been that this is a manifestation of steady state growth due to the balance between the concentration gradient and stress gradient along the confined crystal surface. In this paper, we present experimental results which show that the growth rim is instead formed as a consequence of faceted growth on the confined surface. Steady state growth is not ensured by a gradient in normal stress, but rather a gradient in step density along the crystal face. The loaded crystal surfaces display a high degree of roughness, and the stress is not uniformly distributed across the surface, but transmitted at discrete asperities. We discuss the implications of these findings for the interpretation of previous experimental results, and for the thermodynamics of crystal growth subject to normal stress. 相似文献
83.
Ekeberg D Flaete PO Eikenes M Fongen M Naess-Andresen CF 《Journal of chromatography. A》2006,1109(2):267-272
A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylvestris L.) using gas chromatography (GC) with flame ionization detection (FID) was developed. The limit of detection (LOD) was 0.03 mg/g wood and the linear range (r = 0.9994) was up to 10 mg/g with accuracy within +/- 10% and precision of 18% relative standard deviation. The identification of the extractives was performed using gas chromatography combined with mass spectrometry (GC-MS). The yields of extraction by Soxhlet were tested for solid wood, small particles and fine powder. Small particles were chosen for further analysis. This treatment gave good yields of the most important extractives: pinosylvin, pinosylvin monomethyl ether, resin acids and free fatty acids. The method is used to demonstrate the variation of these extractives across stems and differences in north-south direction. 相似文献
84.
Klaus Wendt Tina Gottwald Dag Hanstorp Christoph Mattolat Sebastian Raeder Sebastian Rothe Fabio Schwellnus Charles Havener Jens Lassen Yuan Liu 《Hyperfine Interactions》2010,196(1-3):151-160
Laser ion sources based on resonant excitation and ionization of atoms are well-established tools for selective and efficient production of radioactive ion beams. A recent trend is the complementary installation of reliable state-of-the-art all solid-state Ti:Sapphire laser systems. To date, 35 elements of the Periodic Table are available at laser ion sources by using these novel laser systems, which complements the overall accessibility to 54 elements including use of traditional dye lasers. Recent progress in the field concerns the identification of suitable optical excitation schemes for Ti:Sapphire laser excitation as well as technical developments of the source in respect to geometry, cavity material as well as by incorporation of an ion guide system in the form of the laser ion source trap LIST. 相似文献
85.
Hakan Durmaz Aydan Dag Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):5083-5091
Well‐defined linear α‐anthracene‐ω‐maleimide functionalized polystyrene (l‐Anth‐PS‐MI) and linear α‐alkyne‐ω‐maleimide functionalized poly(tert‐butyl acrylate) (l‐alkyne‐PtBA‐MI) homopolymers, and linear α‐anthracene‐ω‐maleimide functionalized PS‐b‐PtBA (l‐Anth‐PS‐b‐PtBA‐MI) and linear α‐anthracene‐ω‐maleimide functionalized PS‐b‐poly(ε‐caprolactone) (PCL) (l‐Anth‐PS‐b‐PCL‐MI) block copolymers were obtained via combination of atom transfer radical polymerization (ATRP)/ring opening polymerization (ROP) and azide‐alkyne click reaction strategy. Subsequently, these linear homo and block copolymers were efficiently clicked via Diels‐Alder reaction to give their corresponding cyclic homo and block copolymers at reflux temperature of toluene for 48 h under 7–4 × 10?5 M conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
86.
Schiff base derivatives have gained great importance due to revealing a great number of biological properties. Schiff bases were synthesized by treatment of 4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one ( 1 ) with various aldehydes in methanol at reflux. In addition, diamine was reacted with an aldehyde to yield the corresponding Schiff bases. The structures of synthesized Schiff bases were elucidated by spectroscopic methods such as microanalysis, 1H-NMR, 13C-NMR, and FTIR. Antioxidant activities of synthesized Schiff bases were carried out using different antioxidant assays such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH•) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power activity. (E)-4-((1H-indol-3-yl)methyleneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one ( 3 ), (E)-1,5-dimethyl-4-((2-methyl-1H-indol-3-yl)methyleneamino)-2-phenyl-1H-pyrazol-3(2H)-one ( 5 ), (E)-1,5-dimethyl-2-phenyl-4-(thiophen-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one ( 7 ), (E)-1,5-dimethyl-2-phenyl-4-(quinolin-2-ylmethyleneamino)-1H-pyrazol-3(2H)-one ( 9 ), (1S,2S,N1,N2)-N1,N2-bis((1H-indol-3-yl)methylene)cyclohexane-1,2-diamine ( 11 ), and (1S,2S,N1,N2)-N1,N2-bis((2-methyl-1H-indol-3-yl)methylene)cyclohexane-1,2-diamine ( 12 ) were synthesized in high yields. Compound 5 displayed a good ABTS•+ activity. Compound 3 revealed the outstanding activity in all assays. Compound 7 has the best-reducing power ability in comparison to other synthesized compounds. Although compounds 5, 11, 12 are new, compounds 3, 7, 9 are known. Due to revealing a good antioxidant activity, the synthesized compounds ( 3, 5, 7 ) have the potential to be used as synthetic antioxidant agents. 相似文献
87.
Aydan Dag Hakan Durmaz Okan Sirkecioglu Gurkan Hizal Umit Tunca 《Journal of polymer science. Part A, Polymer chemistry》2009,47(9):2344-2351
The click chemistry strategy is successfully applied for the preparation of three‐arm star (A3) ring opening metathesis polymers. A well‐defined monoazide end‐functionalized poly(N‐ethyl oxanorbornene) and a poly(N‐butyl oxanorbornene) obtained via ring opening metathesis polymerization using first generation Grubbs' catalyst are simply clicked with the trisalkyne core affording the synthesis of target star polymers. The obtained star polymers are characterized via nuclear magnetic resonance spectroscopy and gel permeation chromatography (GPC). The deconvolution analyses of GPC traces reveal that the click reaction efficiency for the star formation strongly depends on the chemical nature and the molecular weight of ROM polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2344–2351, 2009 相似文献
88.
Innocent Joy Kwame Aboh Dag Henriksson Jens Laursen Magnus Lundin Francis Gormon Ofosu Niels Pind Eva Selin Lindgren Tomas Wahnstrm 《X射线光谱测定》2009,38(4):348-353
Small aerosol particles have for a long time been known to be harmful to humans, and are today regarded to cause a larger number of deaths than traffic accidents globally. Energy dispersive x‐ray fluorescence (EDXRF) is a well known method that has been used for identification of toxic as well as non‐toxic elements in the particles. The combination of elements will together with other information help to identify the sources and predict the effects of particles on environment and human health. The present work was conducted in Kwabenya, a suburb of the capital Accra of Ghana, which is frequently exposed to Harmattan dust from the Sahara–Sahel region. In total 171 filters each of PM2.5 and PM(2.5–10) were collected during 1 year. Levels of elements, black carbon (BC) and mass, were determined for both particle sizes. Principal component analysis (PCA) was performed on the datasets from Harmattan and non‐Harmattan periods. The daily average of PM10 was very high, 179 µg m?3 and the BC contents were 4 µg m?3. The presence of crustal elements was large in PM(2.5–10) as well as in PM2.5, and had a more than tenfold increase in PM(2.5–10) during the Harmattan period. Major characteristic elements for different sources were identified from correlation coefficients and regression analysis of the data. Sahara sand aerosol was the major source in both study periods, but influence from biomass burning, sea‐spray and metal industries was also observed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
89.
Panayiotis Alefragis Peter Sanders Tuomo Takkula Dag Wedelin 《Annals of Operations Research》2000,99(1-4):141-166
Performance aspects of a Lagrangian relaxation based heuristic for solving large 0-1 integer linear programs are discussed. In particular, we look at its application to airline and railway crew scheduling problems. We present a scalable parallelization of the original algorithm used in production at Carmen Systems AB, Göteborg, Sweden, based on distributing the variables. A lazy variant of this approach which decouples communication and computation is even useful on networks of workstations. Furthermore, we develop a new sequential active set strategy which requires less work and is better adapted to the memory hierarchy properties of modern RISC processors. This algorithm is also suited for parallelization on a moderate number of networked workstations. 相似文献
90.
Dag W. Breiby Emil J. Samuelsen L. Bert
Groenendaal Bernd Struth 《Journal of Polymer Science.Polymer Physics》2003,41(9):945-952
Sub‐micrometer layers of electrochemically prepared methyl‐ and decyl‐substituted poly(3,4‐ethylenedioxythiophene) (PEDOT) carrying perchlorate counterions have been examined with grazing incidence X‐ray diffraction with synchrotron radiation. The materials were found to be partially crystalline, and the data could be ascribed to a model of sheets of π‐π stacked polymer chains with a smectic ordering of these sheets. An unsubstituted PEDOT sample with the polymeric polystyrenesulfonic acid as a counterion was also investigated and turned out to be essentially amorphous. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 945–952, 2003 相似文献