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91.
The convergent syntheses of 3-deazapurine 2′-deoxy-β-D -ribonucleosides and 2′,3′-dideoxy-D -ribonucleosides, including 3-deaza-2′-deoxyadenosine ( 1a ) and 3-deaza-2′,3′-dideoxyadenosine ( 1b ) is described. The 4-chloro-lH-imidazo[4,5-c]pyridinyl anion derived from 5 was reacted with either 2′-deoxyhalogenose 6 or 2′,3′-dideoxyhalogenose 10 yielding two regioisomeric (N1 and N3) glycosylation products. They were deprotected and converted into 4-substituted imidazo[4,5-c]pyridine 2′-deoxy-β-D -ribonucleosides and 2′,3′-dideoxy-D -ribonucleosides. Compounds 1a and 1b proved to be more stable against proton-catalyzed N-glycosylic bond hydrolysis than the parent purine nucleosides and were not deaminated by adenosine deaminase. 相似文献
92.
Silbernagel KM Jechorek RP Kaufer AL Johnson RL Aleo V Brown B Buen M Buresh J Carson M Franklin J Ham P Humes L Husby G Hutchins J Jechorek R Jenkins J Kaufer A Kexel N Kora L Lam L Lau D Leighton S Loftis M Luc S Martin J Nacar I Nogle J Park J Schultz A Seymore D Smith C Smith J Thou P Ulmer M Voss R Weaver V 《Journal of AOAC International》2005,88(3):750-760
A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance. 相似文献
93.
Man-Kit Lau Qian-Feng Zhang Wing-Tak Wong Wa-Hung Leung 《Journal of organometallic chemistry》2004,689(14):2401-2410
Treatment of [M(Buppy)2Cl]2 (M=Ir (1), Rh (2); BuppyH=2-(4′-tert-butylphenyl)pyridine) with Na(Et2NCS2), K[S2P(OMe)2], and K[N(Ph2PS)2]2 afforded monomeric [Ir(Buppy)2(S∧S)] (S∧S=Et2NCS2 (3), S2P(OMe)2 (4), N(PPh2S)2 (5)) and [Rh(Buppy)2(S∧S)] (S∧S=Et2NCS2 (6), S2P(OMe)2 (7), N(PPh2S)2 (8)), respectively. Reaction of 1 with Na[N(PPh2Se)2] gave [Ir(Buppy)2{N(PPh2Se)2}] (9). The crystal structures of 3, 4, 7, and 8 have been determined. Treatment of 1 or 2 with AgOTf (OTf=triflate) followed by reaction with KSCN gave dinuclear [{M(Buppy)2}2(μ-SCN)2] (M=Ir (10), Rh (11)), in which the SCN− ligands bind to the two metal centers in a μ-S,N fashion. Interaction of 1 and 2 with [Et4N]2[WQ4] gave trinuclear heterometallic complexes [{Ir(Buppy)2}2(μ-WQ4)] (Q=S (12), Se (13)) and [{Rh(Buppy)2}2{(μ-WQ)4}] (Q=S (14), Se (15)), respectively. Hydrolysis of 12 led to formation of [{Ir(Buppy)2}2{W(O)(μ-S)2(μ3-S)}] (16) that has been characterized by X-ray diffraction. 相似文献
94.
Sabine Beernaerts Marie Gerard Philippe Debongnie Jean-Paul Barthelemy Luc Pussemier Alfred Copin 《International journal of environmental analytical chemistry》2013,93(6):469-480
A monitoring study was carried out in 1998-1999 on a medium-sized (c. 4580 km2) watershed of the Dyle (or Dijle) river in central Belgium, composed of both rural and urbanized areas. This watershed may be considered as representative of a large part of the country. Samples were taken each month from seven sites along the course of the river, plus one from its major affluent the Demer. The eight molecules monitored were the main herbicides used on the major crops in the area, plus some used in nonagricultural sectors. The concentrations found were mostly in the 0-3 μg/L range, with some peaks between 3 and 14 μg/L. The averages over all spring and summer samples analyzed ranged from 0.14 (bentazone) to 1.54 μg/L (diuron). Time and space specific patterns could be observed. 相似文献
95.
96.
97.
Elias Nursyafiqah Wahab Roswanira Abdul Jye Lau Woei Mahat Naji Arafat Chandren Sheela Jamalis Joazaizulfazli 《Cellulose (London, England)》2021,28(9):5669-5691
Cellulose - A greener processing route to replace the current environmentally-unfriendly esterification technique to produce biofuels such as pentyl valerate (PeVa) was explored. This study... 相似文献
98.
The (mixed finite element) discretization of the linearized Navier–Stokes equations leads to a linear system of equations of saddle point type. The iterative solution of this linear system requires the construction of suitable preconditioners, especially in the case of high Reynolds numbers. In the past, a stabilizing approach has been suggested which does not change the exact solution but influences the accuracy of the discrete solution as well as the effectiveness of iterative solvers. This stabilization technique can be performed on the continuous side before the discretization, where it is known as ‘grad‐div’ (GD) stabilization, as well as on the discrete side where it is known as an ‘augmented Lagrangian’ (AL) technique (and does not change the discrete solution). In this paper, we study the applicability of ??‐LU factorizations to solve the arising subproblems in the different variants of stabilized saddle point systems. We consider both the saddle point systems that arise from the stabilization in the continuous as well as on the discrete setting. Recently, a modified AL preconditioner has been proposed for the system resulting from the discrete stabilization. We provide a straightforward generalization of this approach to the GD stabilization. We conclude the paper with numerical tests for a variety of problems to illustrate the behavior of the considered preconditioners as well as the suitability of ??‐LU factorization in the preconditioners. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
99.
100.
Philipp Wagener Marcus Lau Sandra Breitung-Faes Arno Kwade Stephan Barcikowski 《Applied Physics A: Materials Science & Processing》2012,108(4):793-799
Combination of wet-grinding and laser fragmentation is a promising approach to advance both methods: Laser fragmentation will be more efficient when combined with mechanical treatment and wet-grinding may take advance of the abrasion-free laser process to achieve fabrication of smaller particles. By mechanical pre-treatment of zinc oxide microparticles in a stirred-media mill, the starting material is activated by generation of crystallographic defects, which strongly enhance the efficiency of subsequent laser fragmentation. Picosecond-laser irradiation of mechanically treated and untreated microparticles suspended in water yielded in colloidal zinc oxide nanoparticles. Furthermore, nanoparticle productivity and properties can be controlled by variation of anionic surfactant concentration. 相似文献