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11.
Arthur Maki Robert L. Sams Jeffrey Barber Engelene t.H. Chrysostom Alfons Weber 《Journal of Molecular Spectroscopy》2004,225(2):109-122
Several new infrared absorption bands for 32S16O3 have been measured and analyzed. The principal bands observed were ν1+ν2 (at 1561 cm−1), ν1+ν4 (at 1594 cm−1), ν3+ν4 (at 1918 cm−1), and 3ν3 (at 4136 cm−1). Except for 3ν3, these bands are very complicated because of (a) the Coriolis coupling between ν2 and ν4, (b) the Fermi resonance between ν1 and 2ν4, (c) the Fermi resonance between ν1 and 2ν2, (d) ordinary l-type resonance that couples levels that differ by 2 in both the k and l quantum numbers, and (e) the vibrational l-type resonance between the A1′ and A2′ levels of ν3+ν4. The unraveling of the complex pattern of these bands was facilitated by a systematic approach to the understanding of the various interactions. Fortunately, previous work on the fundamentals permitted good estimates of many constants necessary to begin the assignments and the fit of the measurements. In addition, the use of hot band transitions accompanying the ν3 band was an essential aid in fitting the ν3+ν4 transitions since these could be directly observed for only one of four interacting states. From the hot band analysis we find that the A1′ vibrational level is 3.50 cm−1 above the A2′ level, i.e., r34=1.75236(7) cm−1. In the case of the 3ν3 band, the spectral analysis is straightforward and a weak Δk=±2, Δl3=±2 interaction between the l3=1 and l3=3 substates locates the latter A1′ and A2′ “ghost” states 22.55(4) cm−1 higher than the infrared accessible l3=1 E′ state. 相似文献
12.
13.
Richard A. Cairncross Jeffrey G. Becker Shri Ramaswamy Ryan O'Connor 《Applied biochemistry and biotechnology》1996,131(1-3):774-785
Management of moisture penetration and hydrolytic degradation of polylactide (PLA) is extremely important during the manufacturing,
shipping, storage, and end-use of PLA products. Moisture transport, crystallization, and degradation, in PLA have been measured
through a variety of experimental techniques including size-exclusion chromatography, differential scanning calorimetry, and
X-ray diffraction. Quartz crystal microbalance and dynamic vapor sorption experiments have also been used to measure moisture
sorption isotherms in PLA films with varying crystallinity. A surprising result is that, within the accuracy of the experiments,
crystalline and amorphous PLA films exhibit identical sorption isotherms. 相似文献
14.
Jeffrey C. Johnson Dawn L. Parks 《Computational & Mathematical Organization Theory》1998,4(3):223-239
Earlier research has shown a relationship between various forms of structural centrality and perceived leadership and role
satisfaction in small experimental groups. The limited amount of research on this topic in naturally occurring social networks
has yielded results that often conflict with one another. Different results have generally been attributed to possible differences
in task environments. This paper examines the relationship between two types of structural centrality and perceived influence,
role satisfaction, and perceived effectiveness in an environmental resource management program. Findings in this paper suggest
that the observed differences in relationships between the network and other variables is partly a function of global network
properties (e.g., marginality of subgroups) and related task environments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
In this paper, we describe an algorithm to stably sort an array ofn elements using only a linear number of data movements and constant extra space, albeit in quadratic time. It was not known previously whether such an algorithm existed. When the input contains only a constant number of distinct values, we present a sequence ofin situ stable sorting algorithms makingO(n lg(k+1)
n+kn) comparisons (lg(K) means lg iteratedk times and lg* the number of times the logarithm must be taken to give a result 0) andO(kn) data movements for any fixed valuek, culminating in one that makesO(n lg*n) comparisons and data movements. Stable versions of quicksort follow from these algorithms.Research supported by Natural Sciences and Engineering Research Council of Canada grant No.A-8237 and the Information Technology Research Centre of Ontario.Supported in part by a Research Initiation Grant from the Virginia Engineering Foundation. 相似文献
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17.
Yan B Collins N Wheatley J Irving M Leopold K Chan C Shornikov A Fang L Lee A Stock M Zhao J 《Journal of combinatorial chemistry》2004,6(2):255-261
We have developed a high-throughput purification system to purify combinatorial libraries at a 50-100-mg scale with a throughput of 250 samples/instrument/day. We applied an accelerated retention window method to shorten the purification time and targeted one fraction per injection to simplify data tracking, lower QC workload, and simplify the postpurification processing. First, we determined the accurate retention time and peak height for all compounds using an eight-channel parallel LC/UV/MS system, and calculated the specific preparative HPLC conditions for individual compounds. The preparative HPLC conditions include the compound-specific gradient segment for individual compounds with a fixed gradient slope and the compound-specific UV or ELSD threshold for triggering a fraction collection device. A unique solvent composition or solvent strength was programmed for each compound in the preparative HPLC in order to elute all compounds at the same target time. Considering the possible deviation of the predicted retention time, a 1-min window around the target time was set to collect peaks above a threshold based on UV or ELSD detection. Dual column preparative instruments were used to maximize throughput. We have purified more than 500 000 druglike compounds using this system in the past 3 years. We report various components of this high-throughput purification system and some of our purification results. 相似文献
18.
Jeffrey T. Culp Franz Frye Mark W. Meisel Daniel R. Talham 《Coordination chemistry reviews》2005,249(23):2642-2648
Studies of metal cyanide thin films prepared directly at interfaces are reviewed. The systems range from monolayers, single-layer analogs of Prussian blue-like networks, to bulk powders prepared as thin films. Monolayer networks are prepared at the air/water interface and transferred to solid supports using Langmuir-Blodgett film methods. Films of bulk materials are prepared directly on solid surfaces using a templated sequential deposition procedure. The magnetic properties of the films have been explored, and in some cases, these monolayers and surface films give rise to new behavior that is only possible because of the fabrication method or thin film architecture. The methods of synthesis can generate oriented samples, even when the materials are poorly crystalline. Furthermore, the interface-assembled networks are inherently anisotropic, leading to phenomena not present in the solid-state analogs, such as anisotropic photomagnetism in a thin film of RbjCok[Fe(CN)6]l·nH2O. 相似文献
19.
1R,2S,5R,8R; 1R,2S,5R,8S; 1S,2S,5R,8R; and 1S,2S,5R,8S-Iridodials have been prepared in five steps from 4aS,7S,7aR and 4aS,7S,7aS-nepetalactones, major components of catnip oil. 1R,2S,5R,8R-Iridodial has been identified as a male-produced male-aggregation pheromone for Chrysopa oculata, the first pheromone of any kind identified for lacewings. 相似文献