Probing the Local Effects of Magnetic Impurities on Superconductivity     

A Yazdani  BA Jones  CP Lutz  MF Crommie  DM Eigler 《Science (New York, N.Y.)》1997,275(5307):1767-1770

The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra.  相似文献   

Spontaneous formation of macroscopic chiral domains in a fluid smectic phase of achiral molecules     

DR Link  G Natale  R Shao  JE Maclennan  NA Clark  E Korblova  DM Walba 《Science (New York, N.Y.)》1997,278(5345):1924-1927

A smectic liquid-crystal phase made from achiral molecules with bent cores was found to have fluid layers that exhibit two spontaneous symmetry-breaking instabilities: polar molecular orientational ordering about the layer normal and molecular tilt. These instabilities combine to form a chiral layer structure with a handedness that depends on the sign of the tilt. The bulk states are either antiferroelectric-racemic, with the layer polar direction and handedness alternating in sign from layer to layer, or antiferroelectric-chiral, which is of uniform layer handedness. Both states exhibit an electric field-induced transition from antiferroelectric to ferroelectric.  相似文献   

Organic Glasses: A New Class of Photorefractive Materials     

PM Lundquist  R Wortmann  C Geletneky  RJ Twieg  M Jurich  VY Lee  CR Moylan  DM Burland 《Science (New York, N.Y.)》1996,274(5290):1182-1185

The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties.  相似文献   

Crystallographic structure of the octameric histone core of the nucleosome at a resolution of 3.3 A   总被引：13，自引：0，他引：13  

R W Burlingame  W E Love  B C Wang  R Hamlin  H X Nguyen  E N Moudrianakis 《Science (New York, N.Y.)》1985,228(4699):546-553

The structure of the (H2A-H2B-H3-H4)2 histone octamer has been determined by means of x-ray crystallographic techniques at a resolution of 3.3 angstroms. The octamer is a prolate ellipsoid 110 angstroms long and 65 to 70 angstroms in diameter, and its general shape is that of a rugby ball. The size and shape are radically different from those determined in earlier studies. The most striking feature of the histone octamer is its tripartite organization, that is, a central (H3-H4)2 tetramer flanked by two H2A-H2B dimers. The DNA helix, placed around the octamer in a path suggested by the features on the surface of the protein, appears like a spring holding the H2A-H2B dimers at either end of the (H3-H4)2 tetramer.  相似文献   

Nanofabrication of Small Copper Clusters on Gold(111) Electrodes by a Scanning Tunneling Microscope     

DM Kolb  R Ullmann  T Will 《Science (New York, N.Y.)》1997,275(5303):1097-1099

The use of scanning tunneling microscopy in an electrochemical environment as a tool for the nanoscale modification of gold electrodes was demonstrated. Small copper clusters, typically two to four atomic layers in height, were precisely positioned on a gold(111) electrode by a process in which copper was first deposited onto the tip of the scanning tunneling microscope, which then acted as a reservoir from which copper could be transferred to the surface during an appropriate approach of the tip to the surface. Tip approach and position were controlled externally by a microprocessor unit, allowing the fabrication of various patterns, cluster arrays, and "conducting wires" in a very flexible and convenient manner.  相似文献   

Laboratory Preparation and Decontamination of Mustard     

Reeves AM  Love S 《Science (New York, N.Y.)》1948,107(2773):204-205

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The Arabidopsis circadian clock incorporates a cADPR-based feedback loop     

Dodd AN  Gardner MJ  Hotta CT  Hubbard KE  Dalchau N  Love J  Assie JM  Robertson FC  Jakobsen MK  Gonçalves J  Sanders D  Webb AA 《Science (New York, N.Y.)》2007,318(5857):1789-1792

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Determination of a chemical basis of air-pollution stress in wood of mature white pine trees in the susceptive forest ecosystems     

S. N. Pathak  D. V. Love  D. N. Roy 《Water, air, and soil pollution》1986,31(1-2):385-392

This paper describes a pilot investigation dealing with changes in chemical composition of wood in pollution-stressed white pine trees, taken from two forested ecosystems of Southern Ontario, Canada. The implications of this research lie in a much needed search for a potential bloindicator of a pre-decline, incipient-stress induced (and/or contributed by) the air-pollutants.  相似文献   

Treatment and prevention of intestinal parasite-associated disease.     

Sandy Love 《Veterinary Clinics of North America: Equine Practice》2003,19(3):791-806

Since 1917, only 11 new endoparasiticides have been developed for the horse, of which five chemical classes are in common use. The selection pressure of frequent administration of deworming doses for parasite control programs has been associated with the development of resistance of small strongyle parasites to the effects of benzimidazoles and pyrantel salts. Against the background of the inevitability of the occurrence of ivermectin/moxidectin resistance, responsible use of equine anthelmintics based on the clinical pharmacology of the compounds and the biology/epidemiology of intestinal parasites is a major issue for equine clinicians. The evidence base for the recommendations for treatment and control of equine intestinal parasites is sparse, however, and few robust data exist from controlled clinical trials to validate current guidelines.  相似文献   

Could the worms have turned?     

S Love  J L Duncan 《Equine veterinary journal》1991,23(3):152-154

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