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991.
Mohammad Saadatfar Adrian P. Sheppard Tim J. Senden Alexandre J. Kabla 《Journal of the mechanics and physics of solids》2012,60(1):55-66
Our understanding of the elasticity and rheology of disordered materials, such as granular piles, foams, emulsions or dense suspensions relies on improving experimental tools to characterise their behaviour at the particle scale. While 2D observations are now routinely carried out in laboratories, 3D measurements remain a challenge. In this paper, we use a simple model system, a packing of soft elastic spheres, to illustrate the capability of X-ray microtomography to characterise the internal structure and local behaviour of granular systems. Image analysis techniques can resolve grain positions, shapes and contact areas; this is used to investigate the material's microstructure and its evolution upon strain. In addition to morphological measurements, we develop a technique to quantify contact forces and estimate the internal stress tensor. As will be illustrated in this paper, this opens the door to a broad array of static and dynamical measurements in 3D disordered systems. 相似文献
992.
Cuihua Xue Singaravelu Velayudham Steve Johnson Ratul Saha Adrian Smith Wilbel Brewer Pushpalatha Murthy Susan T. Bagley Haiying Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2289-2295
Know your bacteria! Two fluorene‐based, conjugated polymers with oligo(ethylene glycol)‐ and poly(ethylene glycol)‐tethered spacers have been prepared by the Suzuki coupling polymerization reactions. β‐Glucose and α‐mannose residues were covalently attached to the conjugated polymers by post‐polymerization functionalization with thiol‐functionalized carbohydrates under basic conditions. Investigations on their use as biosensing materials for the detection of Escherichia coli are reported (see figure).
993.
Superlinear convergence of the Newton method for nonsmooth equations requires a “semismoothness” assumption. In this work we prove that locally Lipschitz functions definable in an o-minimal structure (in particular semialgebraic or globally subanalytic functions) are semismooth. Semialgebraic, or more generally, globally subanalytic mappings present the special interest of being γ-order semismooth, where γ is a positive parameter. As an application of this new estimate, we prove that the error at the kth step of the Newton method behaves like $O(2^{-{(1+\gamma)}^k})$ . 相似文献
994.
Adrian Butscher 《Annals of Global Analysis and Geometry》2009,36(3):221-274
Four constructions of constant mean curvature (CMC) hypersurfaces in
\mathbb Sn+1{\mathbb {S}^{n+1}} are given, which should be considered analogues of ‘classical’ constructions that are possible for CMC hypersurfaces in Euclidean
space. First, Delaunay-like hypersurfaces, consisting roughly of a chain of hyperspheres winding multiple times around an
equator, are shown to exist for all the values of the mean curvature. Second, a hypersurface is constructed which consists
of two chains of spheres winding around a pair of orthogonal equators, showing that Delaunay-like hypersurfaces can be fused
together in a symmetric manner. Third, a Delaunay-like handle can be attached to a generalized Clifford torus of the same
mean curvature. Finally, two generalized Clifford tori of equal but opposite mean curvature of any magnitude can be attached
to each other by symmetrically positioned Delaunay-like ‘arms’. This last result extends Butscher and Pacard’s doubling construction
for generalized Clifford tori of small mean curvature. 相似文献
995.
Aileen Roth Adrian Gihring Florian Gser Christian Peifer Uwe Knippschild Joachim Bischof 《Molecules (Basel, Switzerland)》2021,26(16)
Phosphorylation events catalyzed by protein kinases represent one of the most prevalent as well as important regulatory posttranslational modifications, and dysregulation of protein kinases is associated with the pathogenesis of different diseases. Therefore, interest in developing potent small molecule kinase inhibitors has increased enormously within the last two decades. A critical step in the development of new inhibitors is cell-free in vitro testing with the intention to determine comparable parameters like the commonly used IC50 value. However, values described in the literature are often biased as experimental setups used for determination of kinase activity lack comparability due to different readout parameters, insufficient normalization or the sheer number of experimental approaches. Here, we would like to hold a brief for highly sensitive, radioactive-based in vitro kinase assays especially suitable for kinases exhibiting autophosphorylation activity. Therefore, we demonstrate a systematic workflow for complementing and validating results from high-throughput screening as well as increasing the comparability of enzyme-specific inhibitor parameters for radiometric as well as non-radiometric assays. Using members of the CK1 family of serine/threonine-specific protein kinases and established CK1-specific inhibitors as examples, we clearly demonstrate the power of our proposed workflow, which has the potential to support the generation of more comparable data for biological characterization of kinase inhibitors. 相似文献
996.
Gold nanoparticles have been available for many years as a research tool in the life sciences due to their electron density and optical properties. New applications are continually being developed, particularly in nanomedicine. One drawback is the need for an easy, real-time quantitation method for gold nanoparticles so that the effects observed in in vitro cell toxicity assays and cell uptake studies can be interpreted quantitatively in terms of nanoparticle loading. One potential method of quantifying gold nanoparticles in real time is by chemisorption of iodine-125, a gamma emitter, to the nanoparticles. This paper revisits the labelling of gold nanoparticles with iodine-125, first described 30 years ago and never fully exploited since. We explore the chemical properties and usefulness in quantifying bio-functionalised gold nanoparticle binding in a quick and simple manner. The gold particles were labelled specifically and quantitatively simply by mixing the two items. The nature of the labelling is chemisorption and is robust, remaining bound over several weeks in a variety of cell culture media. Chemisorption was confirmed as potassium iodide can remove the label whereas sodium chloride and many other buffers had no effect. Particles precoated in polymers or proteins can be labelled just as efficiently allowing for post-labelling experiments in situ rather than using radioactive gold atoms in the production process. We also demonstrate that interparticle exchange of I-125 between different size particles does not appear to take place confirming the affinity of the binding. 相似文献
997.
Adrian Wüthrich 《Annalen der Physik》2017,529(5)
One of the first publications by the ATLAS collaboration using data from the Large Hadron Collider at CERN dealt with the measurement of the production cross section of the W boson. The collaboration “rediscovered” the W in order to, among other things, check whether the detector and analysis methods were working well. Originally, the discovery of the W had been announced in 1983 by the CERN management, referring mainly to work done by its UA1 collaboration. In both the discovery and the “rediscovery”, the convergence of two distinct sets of criteria of data selection was an important concern of the researchers. In 1983, this concern figured prominently in the published paper whereas in 2010 it was mainly dealt with inside the collaboration. 相似文献
998.
In this paper, we prove a strong convergence theorem for resolvents of accretive operators in a Banach space by the viscosity approximation method with a generalized contraction mapping. The proximal point algorithm in a Banach space is also considered. The results extend some very recent theorems of W. Takahashi. 相似文献
999.
Nell S. Townsend Adrian B. Chaplin Dr. M. Abu Naser Dr. Amber L. Thompson Dr. Nicholas H. Rees Dr. Stuart A. Macgregor Prof. Andrew S. Weller Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(28):8376-8389
Oxidative addition of aryl bromides to 12‐electron [Rh(PiBu3)2][BArF4] (ArF=3,5‐(CF3)2C6H3) forms a variety of products. With p‐tolyl bromides, RhIII dimeric complexes result [Rh(PiBu3)2(o/p‐MeC6H4)(μ‐Br)]2[BArF4]2. Similarly, reaction with p‐ClC6H4Br gives [Rh(PiBu3)2(p‐ClC6H4)(μ‐Br)]2[BArF4]2. In contrast, the use of o‐BrC6H4Me leads to a product in which toluene has been eliminated and an isobutyl phosphine has undergone C? H activation: [Rh{PiBu2(CH2CHCH3C H2)}(PiBu3)(μ‐Br)]2[BArF4]2. Trapping experiments with ortho‐bromo anisole or ortho‐bromo thioanisole indicate that a possible intermediate for this process is a low‐coordinate RhIII complex that then undergoes C? H activation. The anisole and thioanisole complexes have been isolated and their structures show OMe or SMe interactions with the metal centre alongside supporting agostic interactions, [Rh(PiBu3)2(C6H4O Me)Br][BArF4] (the solid‐state structure of the 5‐methyl substituted analogue is reported) and [Rh(PiBu3)2(C6H4S Me)Br][BArF4]. The anisole‐derived complex proceeds to give [Rh{PiBu2(CH2CHCH3C H2)}(PiBu3)(μ‐Br)]2[BArF4]2, whereas the thioanisole complex is unreactive. The isolation of [Rh(PiBu3)2(C6H4O Me)Br][BArF4] and its onward reactivity to give the products of C? H activation and aryl elimination suggest that it is implicated on the pathway of a σ‐bond metathesis reaction, a hypothesis strengthened by DFT calculations. Calculations also suggest that C? H bond cleavage through phosphine‐assisted deprotonation of a non‐agostic bond is also competitive, although the subsequent protonation of the aryl ligand is too high in energy to account for product formation. C? H activation through oxidative addition is also ruled out on the basis of these calculations. These new complexes have been characterised by solution NMR/ESIMS techniques and in the solid‐state by X‐ray crystallography. 相似文献
1000.
Thompson KC Rennie AR King MD Hardman SJ Lucas CO Pfrang C Hughes BR Hughes AV 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17295-17303
The reaction between gas-phase ozone and monolayers of the unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, on aqueous solutions has been studied in real time using neutron reflection and surface pressure measurements. The reaction between ozone and lung surfactant, which contains POPC, leads to decreased pulmonary function, but little is known about the changes that occur to the interfacial material as a result of oxidation. The results reveal that the initial reaction of ozone with POPC leads to a rapid increase in surface pressure followed by a slow decrease to very low values. The neutron reflection measurements, performed on an isotopologue of POPC with a selectively deuterated palmitoyl strand, reveal that the reaction leads to loss of this strand from the air-water interface, suggesting either solubilization of the product lipid or degradation of the palmitoyl strand by a reactive species. Reactions of (1)H-POPC on D(2)O reveal that the headgroup region of the lipids in aqueous solution is not dramatically perturbed by the reaction of POPC monolayers with ozone supporting degradation of the palmitoyl strand rather than solubilization. The results are consistent with the reaction of ozone with the oleoyl strand of POPC at the air-water interface leading to the formation of OH radicals. The highly reactive OH radicals produced can then go on to react with the saturated palmitoyl strands leading to the formation of oxidized lipids with shorter alkyl tails. 相似文献