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Surface Leads (surface + lead)
Selected AbstractsInteractions between surface proteins of Streptococcus pyogenes and coagulation factors modulate clotting of human plasmaJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2003H. Herwald Summary., Invasive and toxic infections caused by Streptococcus pyogenes are connected with high morbidity and mortality. Typical symptoms of these infections are hypotension, edema formation, tissue necrosis, and bleeding disorders. Here we report that components of the coagulation system including fibrinogen, factors V, XI, and XII, and H-kininogen, are assembled at the surface of S. pyogenes through specific interactions with bacterial surface proteins. In plasma environment, absorption of fibrinogen by S. pyogenes causes a hypocoagulatory state resulting in prolonged clotting times and impaired fibrin network formation. Moreover, the binding of coagulation factors and the subsequent activation of the coagulation system at the bacterial surface lead to the formation of a fibrin network covering S. pyogenes bacteria adhering to epithelial cells. The results suggest that interactions between S. pyogenes and components of the coagulation system contribute to some of the symptoms seen in severe infections caused by this important human pathogen. [source] Multiresolution Surface Representation Based on Displacement VolumesCOMPUTER GRAPHICS FORUM, Issue 3 2003Mario Botsch We propose a new representation for multiresolution models which uses volume elements enclosed between thedifferent resolution levels to encode the detail information. Keeping these displacement volumes locally constantduring a deformation of the base surface leads to a natural behaviour of the detail features. The correspondingreconstruction operator can be implemented efficiently by a hierarchical iterative relaxation scheme, providingclose to interactive response times for moderately complex models. Based on this representation we implement a multiresolution editing tool for irregular polygon meshes that allowsthe designer to freely edit the base surface of a multiresolution model without having to care about self-intersectionsin the respective detailed surface. We demonstrate the effectiveness and robustness of the reconstructionby several examples with real-world data. [source] Fabrication of a Superhydrophobic Surface from a Smectic Liquid-Crystal Defect ArrayADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Yun Ho Kim Abstract A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi-fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ,160° and a sliding angle of ,2° for a 10,µL water droplet. The results show that this phenomenon is due to the development of a dual-scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self-assembly in smectic liquid-crystalline materials. [source] Alkali Metal Doped Organic Molecules on Insulators: Charge Impact on the Optical PropertiesADVANCED MATERIALS, Issue 36 2010Thomas Dienel Doping-induced absorption changes of organic molecules on an insulating solid are reported. The charge transfer between alkali metal atoms and individual molecules on a surface leads to new electronic transitions identified with optical absorption spectroscopy. Progressive doping allows the discrimination of neutral, monoanionic and dianionic molecules in the solid state through examination of the spectra and rate equation modeling. [source] Self-Assembled Pb Nanostructures on Si(111) Surfaces: From Nanowires to NanoringsADVANCED MATERIALS, Issue 45 2009Rui Wu Abstract A template-directed growth method for metals is described in which ordered arrays of super-long single-crystalline metal nanowires with atomic-level-controlled width, thickness (height), and surface location are prepared by molecular beam epitaxy. Their subsequent examination by in situ scanning tunneling microscopy is also outlined. A phase-separated stripe pattern composed of alternately a Ge-rich incommensurate phase and a ,3,×,,3 phase is first obtained by Ge deposition on Si(111) substrates. Further deposition of Pb on this patterned surface leads to a well-ordered array of super-long Pb nanowires. Using the same mechanism, superconducting Pb nanorings can also be fabricated. In this review of our recent work, these Pb single-crystalline nanowires and nanorings are shown to serve as an ideal platform for the study of superconductivity in reduced dimensionalities. Furthermore, because the widths and spatial distributions of two phases can be precisely controlled by the Ge coverage and substrate temperature, and because a metal will always selectively nucleate on one of two phases, this template-directed growth method can be applied to a wide range of metals. [source] In,Situ Microstructure Control of Oriented Layered Double Hydroxide Monolayer Films with Curved Hexagonal Crystals as Superhydrophobic Materials,ADVANCED MATERIALS, Issue 23 2006H. Chen Oriented NiAl-layered double hydroxide (LDH) films with micro-/nanometer scale binary structures are prepared by in,situ crystallization, without using any external aluminum source or shape-directing surfactant, on a porous anodic alumina/aluminum substrate. The NiAl-LDH film structures can be controlled by tuning crystallization temperature and time. Facile hydrophobic modification of the film surface leads to superhydrophobicity, as shown in the figure. [source] Microphotoluminescence spectroscopy of CdSe quantum dots grown on vicinal-surface and exact-orientation substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004T. Makino Abstract We investigated the optical properties of CdSe quantum dots (QDs) grown by molecular-beam epitaxy on GaAs substrates using micro-photoluminescence spectroscopy. Comparison was made between the QDs grown on a substrate with a vicinal tilt of 2° in the [111] direction and those on an on-axis substrate. We have studied the evolution of lineshapes of QD photoluminescence spectra under the improved condition of spatial resolution. It was found that the use of a substrate with the vicinal surface leads to the suppression of excitonic PL emitted from a wetting layer. The PL studies revealed that the thermo-stability up to 150 K was obtained in the sample on the on-axis substrate, whereas rapid temperature-induced quenching starting from 6 K was observed in that grown on the vicinal substrate. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A simple model of coupled synoptic waves in the land surface and atmosphere of the northern SahelTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 637 2008Douglas J. Parker Abstract A simple dynamic model is developed to describe the observed interactions between the atmosphere and the soil moisture patterns of the northern Sahel. In the model, the atmosphere follows quasi-geostrophic dynamics, while land-atmosphere coupling is described by simple linear relationships. Dry surfaces heat the atmospheric boundary layer, while wet surfaces cool the boundary layer, relative to the equilibrium state of the atmosphere and land surface. In turn, cloud processes, which are assumed to maximise in the cool, humid phase of an atmospheric disturbance, cool the land surface through wetting (rainfall) and reduction of the incoming solar flux. These assumptions lead to a linear system which can be solved numerically to obtain modal solutions, and the adjoints (optimal excitation) of these. Moist convective influences on the atmospheric state are not explored in detail. The coupling with the land surface leads to the existence of unstable modes, which do not exist in the atmosphere-only part of the system. Solutions can be easterly or westerly propagating, according to wave number, with the longer waves tending to be easterly. Propagation relies on a favourable configuration between the atmospheric and soil moisture anomalies: easterly propagation requires the surface temperature pattern to be shifted to the east of the atmospheric temperature pattern. In contrast, optimal excitation of the fastest-growing mode occurs when the atmospheric pattern has a thermal anomaly lying to the east of a strong surface temperature (and moisture) anomaly. These results have value for weather prediction, and indicate the usefulness of soil moisture data for forecasters. Copyright © 2008 Royal Meteorological Society [source] Potentiometric Detection of Single Nucleotide Polymorphism by Using a Genetic Field-effect transistorCHEMBIOCHEM, Issue 4 2005Toshiya Sakata Dr. Abstract Potentiometric measurement of allele-specific oligonucleotide hybridization based on the principle of detection of charge-density change at the surface of a gate insulator by using of a genetic field-effect transistor has been demonstrated. Since DNA molecules are negatively charged in aqueous solution, a hybridization event at the gate surface leads to a charge-density change in the channel of the FET and can be directly transduced into an electrical signal without any labeling of target DNA molecules. One of the unique features of our method is to utilize DNA binders such as intercalators as charged species for double-stranded DNA after hybridization, since these are ionized and carry positive charges in aqueous solution. Single-base mismatch of the target DNA could be successfully detected both with the wild-type and with the mutant genetic FETs by controlling the hybridization temperatures and introducing Hoechst 33258 as DNA binder. The genetic FET platform is suitable as a simple, accurate, and inexpensive system for SNP typing in clinical diagnostics. [source] Bioinspired Ribbed Nanoneedles with Robust SuperhydrophobicityADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Xi Yao Abstract The robustness of superhydrophobicity is a fundamental issue for the applications of water-repellent materials. Inspired by the hierarchical structures of water-strider legs, this work describes a new water-repellent material decorated with ribbed, conical nanoneedles, successfully achieved on the surface of copper and consisting of copper hydroxide nanoneedle arrays sculptured with nanogrooves. The behavior of water drops on an as-prepared surface under various external disturbances is investigated. It is shown in particular that squeezing and relaxing drops between two such surfaces leads to a fully reversible exploration of the solid surface by the liquid, which is distinct from other superhydrophobic surfaces. This unique character is attributed to the penetrating Cassie state that occurs at the ribbed, conical nanoneedles. The proprietary lateral nanogrooves can, not only vigorously support the enwrapped liquid-air interface when a force is applied to the drop, but also provide reliable contact lines for the easy de-pinning of the deformed interface when the force is released from the drop. The results confirm the exceptional ability of strider legs to repel water, and should help to further the design of robust water-repellent materials and miniaturized aquatic devices. [source] Analysis of unstirred water layer in in vitro permeability experimentsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2009Timo Korjamo Abstract In vitro permeability experiments are used widely in drug discovery and other areas of pharmaceutical research. Much effort has been expended in developing novel epithelial models but generally much less attention has been paid to the hydrodynamic barrier in the actual experiments. The restricted liquid flow in the vicinity of solid surfaces leads to a zone where the diffusional movement of molecules exceeds the convection. This leads to formation of a concentration gradient between the bulk solution and the surface. The formed unstirred water layer (UWL) reduces the apparent permeability (Papp) of compounds that rapidly pass through the actual epithelial layer. This lowers the resolution of Papp versus fraction-absorbed assay, complicates the structure-permeability analysis and skews apparent kinetic parameters of transporter substrates. This review describes the techniques that can be used to determine the UWL thickness in permeability experiments and apparatuses described in the literature to control the in vitro hydrodynamics. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4469,4479, 2009 [source] Morphology of Symmetric Diblock Copolymers Confined Between Two Stripe-Patterned Surfaces , Tilted Lamellae and MoreMACROMOLECULAR THEORY AND SIMULATIONS, Issue 2 2005Qiang Wang Abstract Summary: We report the first Monte Carlo simulations on the thin-film morphology of symmetric diblock copolymers confined between either symmetrically or antisymmetrically stripe-patterned surfaces. Under suitable surface configurations (where the lamellae can comply with the surface patterns and can have a period close to the bulk lamellar period L0), tilted lamellae are observed for film thicknesses D,,,2L0; the checkerboard morphology is obtained for smaller film thicknesses. The A-B interfaces in the tilted lamellae are basically perpendicular to the surfaces in their immediate vicinity, and exhibit undulations away from them. In some cases, the severe frustration imposed by the two patterned surfaces leads to irregular or unexpected morphologies, which represent locally stable states. The efficient sampling of our expanded grand-canonical Monte Carlo technique enables us to observe more than one locally stable morphologies and the flipping between them during a single simulation run. Tilted lamellae between symmetrically patterned surfaces (perpendicular to z) with a surface pattern period of 1.5L0 and a film thickness of 2.67L0. L0 is the bulk lamellar period and the black curves mark the A-B interfaces. [source] | |||||||||||||