716 research outputs found

    Critical dynamics of diluted relaxational models coupled to a conserved density (diluted model C)

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    We consider the influence of quenched disorder on the relaxational critical dynamics of a system characterized by a non-conserved order parameter coupled to the diffusive dynamics of a conserved scalar density (model C). Disorder leads to model A critical dynamics in the asymptotics, however it is the effective critical behavior which is often observed in experiments and in computer simulations and this is described by the full set of dynamical equations of diluted model C. Indeed different scenarios of effective critical behavior are predicted.Comment: 4 pages, 5 figure

    First insights on plasma orthodontics - Application of cold atmospheric pressure plasma to enhance the bond strength of orthodontic brackets

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    Objective: The development of an ideal adhesive system has long been subject of research. Recent studies show that treatment with cold atmospheric pressure plasma (CAP) positively affects the bonding properties of enamel. Conditioning with CAP could therefore improve the mechanical and physical properties of bracket adhesives, e.g. Glass ionomer cement (GIC). Material and methods: Laser-structured brackets (Dentaurum, Ispringen) were bonded onto 60 bovine mandibular incisors using different orthodontic adhesives. For 20 specimens FujiOrthoLC (GC America Corp, Alsip, USA) was used according to manufacturer's instructions. Another 20 specimens received a 60 s CAP-treatment (kINPen med, Neoplas tool, Greifswald, Germany) before bracket bonding, of which 10 were re-moistened before applying FujiOrthoLC and 10 remained dry. Onto 20 specimens, brackets were bonded with the Composite Transbond XT (3M/Unitek, St. Paul, USA) following manufacturer's instructions. The shear bond strength of brackets on the teeth was determined with the universal testing machine Zwick BZ050/TH3A (Zwick, Ulm, Germany). Results: Brackets bonded with FujiOrthoLC in standard method, showed average shear bond strength of 5.58±0.46 MPa. Specimens treated with plasma showed clinically unacceptable adhesion values (re-moistened group: 2.79±0.38 MPa, dry group: 1.01±0.2 MPa). Bonding onto dried out teeth also led to spontaneous bracket losses (4 of 10 specimens). The composite group (Transbond XT) showed clinically acceptable adhesion values (7.9±1.03 MPa). Conclusions: Despite promising potential, surface conditioning with CAP could not improve the adhesive properties of GIC. By contrast, a decrease in shear bond strength was noticed after CAP treatment. Further investigations have to show whether it is possible to increase the retention values ​​of other orthodontic adhesives by CAP application and thus take advantage of positive characteristics and reduce side effects

    Morphogenesis and Malformations of the Skin NICHD/NIADDK Research Workshop

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    Developmentally caused skin malformations constitute a spectrum of birth defects, some of which can be recognized prenatally by morphologic or biochemical means. The number of prenatally diagnosable skin diseases could be greatly expanded with an increased understanding of the molecular and cellular bases of skin development and the mechanisms that result in the generation of skin defects. The National Institute of Child Health and Human Development and the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, therefore, sponsored a workshop that recommended basic biologic studies combined with clinical investigations of normal and abnormal cutaneous development set forth in this article. Investigations resulting from these research recommendations are intended to contribute to the knowledge that should aid in the prevention of developmentally caused skin deformities

    Produktionsbiologische und hydrographische Untersuchungen in der Eckernförder Bucht

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    1964 wurden in der Eckernförder Bucht hydrographische und produktionsbiologische Untersuchungen durchgefĂŒhrt, wobei der Schwerpunkt auf der Bestimmung des partikulĂ€ren Kohlenstoffs und des partikulĂ€ren Phosphors lag. Die erhaltenen Resultate werden in Diagrammen gezeigt. In 1964 combined hydrographic and productivity measurements were started in the Bay of Eckernförde with recently developed instruments. Especially the recording instruments for determination of total and particulate organic carbon and particulate phosphorus were examined. Some results are given in diagrams, which offer an idea of the hydrographical situation and the start of the spring bloom of phytoplankton

    Global and local envelope protein dynamics of hepatitis C virus determine broad antibody sensitivity

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    Broad antibody sensitivity differences of hepatitis C virus (HCV) isolates and their ability to persist in the presence of neutralizing antibodies (NAbs) remain poorly understood. Here, we show that polymorphisms within glycoprotein E2, including hypervariable region 1 (HVR1) and antigenic site 412 (AS412), broadly affect NAb sensitivity by shifting global envelope protein conformation dynamics between theoretical “closed,” neutralizationresistant and “open,” neutralization-sensitive states. The conformational space of AS412 was skewed toward -hairpin–like conformations in closed states, which also depended on HVR1, assigning function to these enigmatic E2 regions. Scavenger receptor class B, type I entry dependency of HCV was associated with NAb resistance and correlated perfectly with decreased virus propensity to interact with HCV co-receptor CD81, indicating that decreased NAb sensitivity resulted in a more complex entry pathway. This link between global E1/E2 states and functionally distinct AS412 conformations has important implications for targeting AS412 in rational HCV vaccine design

    Exchange Effects in the Invar Hardening: Fe0.65Ni0.35Fe_{0.65}Ni_{0.35} as a test case

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    An increase of the critical resolved shear stress of Invar alloys (Invar hardening) with a lowering temperature is explained. The effect is caused by a growth of the exchange interaction between dangling dd-electron states of dislocation cores and paramagnetic obstacles (e.g., Ni atoms in FeNi alloys) which occurs below the Curie temperature. The spins of the two electrons align along the magnetization due to the exchange interaction with the surrounding atoms of the ferromagnetic. The exchange interaction between the dislocations and obstacles is enhanced in Invars due to a strong growth of the magnetic moments of atoms under the action of elastic strains near the dislocation cores. Parameters characterizing the exchange interaction are determined for the case of the Fe0.65_{0.65}Ni0.35_{0.35} Invar. The influence of the internal magnetic field on the dislocation detachment from the obstacles is taken into account. The obtained temperature dependence of the critical resolved shear stress in the Fe0.65_{0.65}Ni0.35_{0.35} Invar agrees well with the available experimental data. Experiments facilitating a further check of the theoretical model are suggested.Comment: 8 pages, 2 figure

    Absence of Meissner State and Robust Ferromagnetism in the Superconducting State of UCoGe: Possible Evidence of Spontaneous Vortex State

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    We report ac magnetic susceptibility and dc magnetization measurements on the superconducting ferromagnet UCoGe (with superconducting and Curie temperatures of TSC∌0.5T_{{\rm SC}} \sim 0.5~K and TCurie∌2.5T_{{\rm Curie}} \sim 2.5~K, respectively). In the normal, ferromagnetic state (TSC<T<TCurieT_{{\rm SC}} < T < T_{{\rm Curie}}), the magnetization curve exhibits a hysteresis loop similar to that of a regular itinerant ferromagnet. Upon lowering the temperature below TSCT_{{\rm SC}}, the spontaneous magnetization is unchanged, but the hysteresis is markedly enhanced. Even deeply inside the superconducting state, ferromagnetism is not completely shielded, and there is no Meissner region, a magnetic field region of H<Hc1H < H_{\rm c1} (a lower critical field). From these results, we suggest that UCoGe is the first material in which ferromagnetism robustly survives in the superconducting state and a spontaneous vortex state without the Meissner state is realized.Comment: 5 pages, 4 figures, to be published in J. Phys. Soc. Jp
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