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51.
Wenqing Yin Yongcheng Lin Zhigang She L. L. P. Vrijmoed E. B. Gareth Jones 《Chemistry of Natural Compounds》2008,44(1):3-5
A new metabolite xyloketal H (1), was isolated from mangrove fungus Xylaria sp. (No.2508) obtained from the South China Sea. By spectroscopic analyses, primarily 2D NMR methods and X-ray diffraction
experiments, its structure was elucidated.
Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 5–6, January–February, 2008. 相似文献
52.
Using filament stretching rheometry to predict strand formation and “processability” in adhesives and other non-Newtonian fluids 总被引:1,自引:0,他引:1
The spinning of polymeric fibers, the processing of numerous foodstuffs and the peel and tack characteristics of adhesives
are all associated with the formation, stability and, ultimately, the longevity of thin fluid `strands'. This tendency to
form strands is usually described in terms of the tackiness of the fluid or by heuristic concepts such as `stringiness' (Lakrout
et al. J Adhesion 1999). The dynamics of such processes are complicated due to spatially and temporally non-homogeneous growth
of extensional stresses, the action of capillary forces and the evaporation of volatile solvents. We describe the development
and application of a simple instrument referred to as a microfilament rheometer (MFR) that can be used to readily differentiate
between the dynamical response of different pressure-sensitive adhesive fluid formulations. The device relies on a quantitative
observation of the rate of extensional thinning or `necking' of a thin viscous or viscoelastic fluid filament in which the
solvent is free to evaporate across the free surface. This high-resolution measurement of the radial profile provides a direct
indication of the ultimate time to break up of the fluid filament. This critical time is a sensitive function of the rheological
properties of the fluid and the mass transfer characteristics of the solvent, and can be conveniently reported in terms of
a new dimensionless quantity we refer to as a processability parameter P. We demonstrate the usefulness of this technique by presenting our results in the form of a case study in which we measure
the visco-elasto-capillary thinning of slender liquid filaments for a number of different commercial polymer/solvent formulations
and relate this to the reported processing performance of the materials. We also compare the MFR observations with the prediction
of a simple 1D theory derived from the governing equations that model the capillary thinning of an adhesive filament.
Received: 22 December 1999/Accepted: 4 January 2000 相似文献
53.
Chiral and achiral bipyridines are readily accessible via a solvent-free Michael addition involving solid NaOH, followed by treatment with ammonium acetate in acetic acid, as a ‘one pot’ more benign protocol, affording pure products in high yield, typically >80%. 相似文献
54.
55.
George A. Koutsantonis Jackson Lee Nigel A. Lengkeek Gareth L. Nealon Brian W. Skelton Allan H. White 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(1-2):61-66
The synthesis and single-crystal x-ray structure determination of two new trinuclear metal complexes is detailed. In these we utilise the appended iminodiacetate substituents, in [Co(CH3)NH(CH2CO2H)2sar]3+, to act as a focus for coordination of other metal ions. Thus, we have made complexes of Cu and Ni utilising the basic carbonates of these metals and [Co(CH3){N(CH2CO2H)2}sar]3+ (CoL2) which gave rise to ((CoL2–2H+)2M), M = Cu and Ni. The electrochemical study of the latter was inconclusive and provides the impetus for further study. 相似文献
56.
Gareth P. Keeley Niall McEvoy Shishir Kumar Nikos Peltekis Marcel Mausser Georg S. Duesberg 《Electrochemistry communications》2010,12(8):1034-1036
This communication describes the electrochemical properties of thin pyrolytic carbon (PyC) films created using a reliable, non-catalytic chemical vapour deposition (CVD) process. After deposition, the electron transfer characteristics of the films are optimised using a simple oxygen plasma treatment. The redox probes Ru(NH3)63+/2+, Fe(CN)63?/4? and Fe3+/2+ are employed to demonstrate that the resulting material is endowed with a large electrochemical surface area and outstanding electron transfer properties. Atomic force microscopy (AFM), Raman and X-ray photoelectron spectroscopy (XPS) are used to elucidate the morphology and chemical composition of the electrode surfaces. This material represents a new class of carbon electrode, and its large densities of edge-plane sites and oxygenated functionalities make it an ideal candidate for electrochemical sensor applications. 相似文献
57.
A. Gareth Brenton A. Ruth Godfrey 《Journal of the American Society for Mass Spectrometry》2010,21(11):1821-1835
High-resolution mass spectrometry has become ever more accessible with improvements in instrumentation, such as modern FT-ICR
and Orbitrap mass spectrometers. This has resulted in an increase in the number of articles submitted for publication quoting
accurate mass data. There is a plethora of terms related to accurate mass analysis that are in current usage, many employed
incorrectly or inconsistently. This article is based on a set of notes prepared by the authors for research students and staff
in our laboratories as a guide to the correct terminology and basic statistical procedures to apply in relation to mass measurement,
particularly for accurate mass measurement. It elaborates on the editorial by Gross in 1994 regarding the use of accurate
masses for structure confirmation [1]. We have presented and defined the main terms in use with reference to the International
Union of Pure and Applied Chemistry (IUPAC) recommendations for nomenclature and symbolism for mass spectrometry. The correct
use of statistics and treatment of data is illustrated as a guide to new and existing mass spectrometry users with a series
of examples as well as statistical methods to compare different experimental methods and datasets. 相似文献
58.
Andrzej Rajca Prof. Velavan Kathirvelu Dr. Sandip K. Roy Dr. Maren Pink Dr. Suchada Rajca Dr. Santanu Sarkar Sandra S. Eaton Prof. Gareth R. Eaton Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5778-5782
Site‐directed spin labeling and EPR spectroscopy offer accurate, sensitive tools for the characterization of structure and function of macromolecules and their assemblies. A new rigid spin label, spirocyclohexyl nitroxide α‐amino acid and its N‐(9‐fluorenylmethoxycarbonyl) derivative, have been synthesized, which exhibit slow enough spin‐echo dephasing to permit accurate distance measurements by pulsed EPR spectroscopy at temperatures up to 125 K in 1:1 water/glycerol and at higher temperatures in matrices with higher glass transition temperatures. Distance measurements in the liquid nitrogen temperature range are less expensive than those that require liquid helium, which will greatly facilitate applications of pulsed EPR spectroscopy to the study of structure and conformation of peptides and proteins. 相似文献
59.
Flávio B. Gonçalves Gareth O. Roberts 《Methodology and Computing in Applied Probability》2014,16(4):907-930
Exact simulation of SDEs is a very important and challenging problem. In this paper we discuss exact simulation problems for jump-diffusion processes. Motivated by statistical applications, our main contribution is to propose an algorithm that performs exact simulation of a class of jump-diffusion bridges. We also present and discuss the existing methods for forward simulation and propose an extension of one of them to account for unbounded jump rate. Finally, the exact algorithms are compared to competing non-exact ones in some simulated examples. 相似文献
60.
Gareth J. Rowlands Author Vitae 《Tetrahedron》2010,66(9):1593-501