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181.
Sweeney CM Nehl CL Hasan W Liang T Eckermann A Meade TJ Odom TW 《The journal of physical chemistry. C, Nanomaterials and interfaces》2011,115(32):15933-15937
A three-channel spectrometer (3CS) based on a commercial digital camera was developed to distinguish among tens of large (>100 nm), anisotropic plasmonic particles with various shapes, orientations, and compositions on a surface simultaneously. Using band pass filters and polarizers, the contrast of 3CS images could be enhanced to identify specific orientation and composition characteristics of gold and gold-silver nanopyramids and as well as the direction of the longest arm of gold nanostars. 相似文献
182.
183.
Previous research on adaptive harvest strategies has suggested that it should rarely be optimal to introduce deliberate, probing variations in harvest rates in order to reduce uncertainty about production parameters, when there is strong aversion to the risk of low catches. Here we show that this suggestion is incorrect for cases where the stock dynamics can be approximated by a simple power model and the objective is to maximize the sum over time of discounted logarithms of catches. In such cases, the objective function has a simple form that permits easy comparison between passively adaptive (certainty equivalent or cautious) versus actively adaptive policies involving probing variation in harvest rates. Probing is favored when there is high uncertainty about the power parameter that represents density dependence in the stock dynamics. 相似文献
184.
Cluster analysis and principal components analysis have been used to classify nine octadecyl (C18) high-performance liquid chromatography (HPLC) columns into three general groups displaying similar chromatographic behaviour. Principal components analysis was also able to identify the key test compounds on which the classification was most highly dependent. These identifications agreed with the classification and test compound selection by an HPLC specialist. In addition, the chemometric techniques can easily be extended to many more columns and test measurements than could be conveniently examined by a human expert. 相似文献
185.
186.
Russel M. Walters Karen E. Sohn Karen I. Winey Russell J. Composto 《Journal of Polymer Science.Polymer Physics》2002,40(24):2833-2841
The local environment of unneutralized carboxylic acid groups in poly(ethylene‐ran‐methacrylic acid) (E/MAA) ionomers neutralized with monovalent (Li and Na) and divalent (Ca and Zn) ions has been investigated with Fourier transform infrared spectroscopy. These unneutralized acid groups interact with one another to form acid dimers, and they associate with existing neutralized complexes. At room temperature, no free acids can be detected for any system, not even for pure E/MAA. With the acid dimer peak (1700 cm?1) and a known unneutralized acid concentration, the concentration of acids associated with a neutralized complex can be determined. This concentration of associated acids increases with increasing neutralization, reaches a maximum below 50% neutralization, and then decreases toward zero near 80% neutralization. This behavior is perhaps due to the increased driving force for aggregation of the neutralization acids. Although Li, Na, and Ca contain similar concentrations of associated acids over the range of neutralizations, the Zn system contains far fewer associated acids (i.e., more acid dimers) at any particular neutralization level. These results are confirmed by an analysis of the absorbance in the neutralized region (1650–1500 cm?1). © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2833–2841, 2002 相似文献
187.
Robert Vestberg Christina Nilsson Cesar Lopes Per Lind Bertil Eliasson Eva Malmstrm 《Journal of polymer science. Part A, Polymer chemistry》2005,43(6):1177-1187
The synthesis and characterization of dendron‐coated 2,5‐bis(phenylethynyl)thiophene chromophores are described. The dendrimers were grown divergently on the arylthiophene core with the versatile anhydride of 2,2‐bis(methylol)propionic acid. The arylthiophene core was synthesized with Sonogashira coupling reactions. Structurally well‐defined dendrimers up to the fourth generation were grown, as confirmed by size exclusion chromatography, NMR, and matrix‐assisted laser desorption/ionization time‐of‐flight analysis. The different dendritic substitution did not influence the absorption spectra of the compounds in or near the visible region. Solutions of arylthiophenes had good transparency at wavelengths greater than 400 nm. The dendritic thiophenes exhibited an optical‐power limit at the laser wavelength of 532 nm. However, the magnitude of the optical‐power limit of these compounds was slightly lower than that of a nondendritic arylthiophene with n‐pentyl substituents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1177–1187, 2005 相似文献
188.
Shing Horng Lee Christina F. Jou Chien Ping Lee Cheng Chi Hu 《International Journal of Infrared and Millimeter Waves》1997,18(10):2001-2017
A simple varactor tuned X-band Gunn diode VCO antenna array which is strongly coupled has been demonstrated. These arrays
have the advantages of simple biasing circuit, no resistors required to eliminate multimode problem and suitable for monolithic
integration circuit. Preliminary results show a maximum tuning range of 47MHz for 1×1 array and 170MHz for 2×2 array. In order
to solve power combining heating problem, we move the backside metal forward and it becomes a microstrip form. The measured
frequency and radiation patterns of these grid arrays agree very well with theoretical calculations. 相似文献
189.
A new type of biosensor is introduced, based on a novel internal enzyme system which separates the sample solution from the analytical reaction. The bioanalyte diffuses through a gas-permeable membrane into the internal enzyme solution. A reaction that includes the bioanalyte is catalysed and the rate of this reaction is related to the bioanalyte concentration. The first example of this type of biosensor is illustrated by the development of a fiber-optic internal enzyme biosensor for ethanol. Alcohol dehydrogenase is the enzyme and the rate of production of reduced nicotinamide adenine dinucleotide is measured. Results that demonstrate the feasibility of the internal enzyme system are presented and the relative merits of this type of biosensor are discussed. 相似文献
190.
Wilfried Imrich J.M.S Simões-Pereira Christina M Zamfirescu 《Journal of Combinatorial Theory, Series B》1984,36(1):1-15
This paper extends previous results of the authors. In particular, non-treerealizable metrics are investigated and it is shown that every finite metric has an optimal realization by a graph. 相似文献