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11.
By stacking alternatively rotated gallium phosphide (GaP) plates, the maximum photon conversion efficiency of 40% for the terahertz (THz) generation based on difference-frequency generation has been achieved. The corresponding peak power generated inside the four GaP plates approaches 4 kW. As the number of plates is increased from four to five, the THz output power is significantly decreased, due to back parametric conversion. 相似文献
12.
Hodgkinson JT Galloway WR Wright M Mati IK Nicholson RL Welch M Spring DR 《Organic & biomolecular chemistry》2012,10(30):6032-6044
Many species of bacteria employ a mechanism of intercellular communication known as quorum sensing which is mediated by small diffusible signalling molecules termed autoinducers. The most common class of autoinducer used by Gram-negative bacteria are N-acylated-L-homoserine lactones (AHLs). Pseudomonas aeruginosa is a clinically important bacterium which is known to use AHL-mediated quorum sensing systems to regulate a variety of processes associated with virulence. Thus the selective disruption of AHL-based quorum sensing represents a strategy to attenuate the pathogenicity of this bacterium. Herein we describe the design, synthesis and biological evaluation of a collection of structurally novel AHL mimics. A number of new compounds capable of modulating the LasR-dependent quorum sensing system of P. aeruginosa were identified, which could have value as molecular tools to study and manipulate this signalling pathway. Worthy of particular note, this research has delivered novel potent quorum sensing antagonists, which strongly inhibit the production of virulence factors in a wild type strain of this pathogenic bacterium. 相似文献
13.
Ketoreductases were utilized for the stereoselective synthesis of δ-hydroxy-β-keto esters, β-hydroxy-δ-keto esters, and β,δ-dihydroxy esters. Seven out of eight possible stereoisomers were obtained from the enzymatic reduction of the corresponding β,δ-diketo ester in high enantio- and diastereomeric excess. 相似文献
14.
15.
Ioulia Smonou 《合成通讯》2013,43(14):1999-2002
A convenient one step reduction of diaryl ketones to hydrocarbons using etherated boron trifluoride-triethylsilane is described. 相似文献
16.
McCauley MJ Chaurasiya KR Paramanathan T Rouzina I Williams MC 《Physics of life reviews》2010,7(3):358-361
17.
Sophia Mitkidou Evagelia Dimitrakoudi Dushka Urem-Kotsou Despina Papadopoulou Kostas Kotsakis John A. Stratis Ioulia Stephanidou-Stephanatou 《Mikrochimica acta》2008,160(4):493-498
Organic residues associated with Neolithic pottery from two Late Neolithic sites, Paliambela and Makriyalos (Northern Greece),
were analyzed by gas chromatography-mass spectrometry. The study aimed at identifying the origin of the tar used for waterproofing
and gluing broken pots. Reference tars were prepared in laboratory conditions by pyrolysis of the bark from three tree species,
namely from Betula pendula (silver birch), Ostrya carpinifolia (hop hornbeam) and Carpinus orientalis (Eastern hornbeam). The results suggest that mostly birch bark tar was used as glue for fixing broken pieces of the pots
as well as for waterproofing close-shaped vessels. None of the archaeological tars derived from the two hornbeams. The analysis
shows certain variability in the composition of birch bark tar, which is related to the production technique and to the re-use
of tar. Of particular interest is the presence of characteristic diterpenoid biomarkers in several samples, which indicates
that pine pitch was used for gluing and pine resin for waterproofing vessels for liquids.
Correspondence: Sophia Mitkidou, Department of Science, School of Technological Applications, Technological Institute of Kavala,
Greece 相似文献
18.
Paramanathan T Westerlund F McCauley MJ Rouzina I Lincoln P Williams MC 《Journal of the American Chemical Society》2008,130(12):3752-3753
The dumbbell shaped binuclear ruthenium complex DeltaDelta-P requires transiently melted DNA in order to thread through the DNA bases and intercalate DNA. Because such fluctuations are rare at room temperature, the binding rates are extremely low in bulk experiments. Here, single DNA molecule stretching is used to lower the barrier to DNA melting, resulting in direct mechanical manipulation of the barrier to DNA binding by the ligand. The rate of DNA threading depends exponentially on force, consistent with theoretical predictions. From the observed force dependence of the binding rate, we demonstrate that only one base pair must be transiently melted for DNA threading to occur. 相似文献
19.
Diaryl or aryl alkyl carbinols bearing a second reducible functional group (such as hydroxyl or ester) are selectively deoxygenated in high yields by the action of etherated boron trifluoride and triethyl silane reducing system. 相似文献
20.
It is shown how a full Newton–Raphson technique speeds up in impressive proportions the iterative resolution of molecular integral equations and makes it possible to reach quadratically complete convergence down to machine precision in a very few cycles. The technique generalises what has been originally proposed by Zerah and extensively used since then with great success for various fluids and mixtures of spherical objects. At each main iteration, the linearised cycle obtained by differentiating the Ornstein–Zernike and the integral equations is itself solved iteratively in terms of Δgmnlμν(r) projections. Its solution is reached very rapidly thanks to the powerful biconjugate gradient method and to the absence of any Euler angle manipulation. The virial equation is written in a shape formally different from the standard one, which allows a much higher numerical precision for the pressure without extra numerical work. The complete scheme is illustrated on the popular SPC/E water model. 相似文献