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Wiseman G 《Journal of AOAC International》2002,85(3):792-796
Consequential to the implementation of European Commission (EC) Regulation 1139/98, EC Regulation 49/2000, and EC Regulation 50/2000 has been the need to measure accurately the levels of the genetically modified (GM) species Roundup Ready Soya and Bt 176 Maize that are present in food. Analytical methods to detect and quantitate these transgenic species have received much attention particularly with respect to the deminimus threshold of 1% for their presence in materials derived from non-GM identity-preserved (IP) supplies. The relative advantages and limitations of threshold analysis by double-competitive polymerase chain reaction (PCR) and quantitative real-time PCR are discussed in their application to the quantitative analysis of processed foods. Consideration is also given to other factors involved in the analyses that affect the performance of quantitative procedures, and to the many uncertainties involved in the precision of a reported analytical result. 相似文献
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The range of chemical flexibilities of the hexagonal frameworks (Ta6Si4O26)6? and (Ta14Si4O47)8? have been partially explored. This has been done with high-temperature preparations as in general ionic mobilities in these frameworks are too low to permit low-temperature ion exchange. Ionic site potential calculations indicate that preferential site-occupancy factors as well as geometric constraints are responsible for the absence of ionic motion. New phases K6?xNaxTa6Si4O26 (x ? 4), K8?xNaxTa14Si4O47 (x ? 5), and impure Ba3?xNa2xTa6Si4O26 have been prepared. Introduction of up to 2 moles of Li+ and 1 mole of Mg2+ ions per formula unit into sites of the framework not normally occupied has been demonstrated as well as the possibility of partially substituting Zr4+ for Ta5+ ions. Substitutions designed to introduce large tunnel vacancies in the presence of only monovalent K+ or Na+ ions (P for Si, W for Ta and F for O) generally proved unsuccessful. Competitive phases also frustrated attempts to substitute either the larger Rb+ or the smaller Li+ ions into the large-tunnel sites. A large area of solid solution was discovered in the BaONa2OTa2O5 phase diagram; it has a (TaO3)-framework with the structure of tetragonal potassium tungsten bronze. 相似文献
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Christopher Batich Edgar Heilbronner Clayton B. Quinn John R. Wiseman 《Helvetica chimica acta》1976,59(2):512-522
Photoelectron spectroscopy has been used to examine the consequences of steric inhibition of conjugation in a distorted vinyl sulfide and vinyl ether. Based upon the degree of interaction a deviation from coplanarity of 70°–75° is calculated for 9-oxabicyclo[3.3.1]non-1-ene ( 3 ) and approximately 75°–80° for the sulfur analog 6 . 相似文献
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Fabio Drucker David Richeson Jim Wiseman 《Journal of Dynamics and Differential Equations》2016,28(2):301-315
We consider shift spaces in which elements of the alphabet may overlap nontransitively. We define a notion of entropy for such spaces and show that it is equal to a limit of entropies of standard (non-overlapping) shifts when the underlying shift is of finite type. When a shift space with overlaps arises as a model for a discrete dynamical system with a finite set of overlapping neighborhoods, the entropy gives a lower bound for the topological entropy of the dynamical system. 相似文献
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J. R. Wells Floyd L. Wiseman Dale C. Williams J. Steven Baxley D. F. Smith 《国际化学动力学杂志》1996,28(7):475-480
The gas-phase reaction products of the OH radical with 2-ethoxyethyl acetate (EEA, CH3C(O)OCH2CH2OCH2CH3) have been investigated. 1,2-Ethanediol acetate formate (EAF, CH3C(O)OCH2CH2OC(O)H) and ethyl formate (EF, HC(O)OCH2CH3) were identified as the two main products. A third product, ethylene glycol diacetate (EGD, CH3C(O)OCH2CH2OC(O)CH3), was also observed. EAF, EF, and EGD formation yields were determined to be 0.37 ± 0.03 and 0.328 ± 0.018 and 0.040 ± 0.005, respectively. Proposed reaction mechanisms are discussed and compared with these data. © 1996 John Wiley & Sons, Inc. 相似文献
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Detection of a single photon escaping an optical cavity QED system prepares a nonclassical state of the electromagnetic field. The evolution of the state can be modified by changing the drive of the cavity. For the appropriate feedback, the conditional state can be captured (stabilized) and then released. This is observed by a conditional intensity measurement that shows suppression of vacuum Rabi oscillations for the length of the feedback pulse and their subsequent return. 相似文献