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Soft, pneumatic actuators that buckle when interior pressure is less than exterior provide a new mechanism of actuation. Upon application of negative pneumatic pressure, elastic beam elements in these actuators undergo reversible, cooperative collapse, and generate a rotational motion. These actuators are inexpensive to fabricate, lightweight, easy to control, and safe to operate. They can be used in devices that manipulate objects, locomote, or interact cooperatively with humans, as described by G. M. Whitesides and co-workers on page 6323.
OBJECTIVE—The purpose of this study was to investigate whether adiponectin concentrations and biomarkers of inflammation, endothelial dysfunction, and insulin resistance mediate the association between alcohol consumption and diabetes. RESEARCH DESIGN AND METHODS—In a nested case-control study of 705 women with incident diabetes and 787 matched control subjects, we examined the adjusted relationship between baseline alcohol consumption and risk of diabetes before and after adjustment for markers of inflammation/endothelial dysfunction (C-reactive protein, vascular cell adhesion molecule-1, intercellular adhesion molecule-1, E-selectin, tumor necrosis factor-α receptor 2, and interleukin-6), fasting insulin, and adiponectin concentrations. RESULTS—Alcohol consumption was associated with a decreased risk of diabetes (odds ratio per 12.5 g/day increment in alcohol use 0.58; 95% CI 0.49–0.69; P < 0.001). Adjustment for BMI attenuated the association by 25%. None of the markers of inflammation or fasting insulin appeared to account for >2% of the observed relationship. Without adjustment for BMI, these biomarkers individually explained slightly more of the association, but <10% in all cases. Adiponectin accounted for 25% in a fully adjusted model and for 29% without adjustment for BMI. CONCLUSIONS—In this population of women, alcohol consumption was inversely associated with risk of type 2 diabetes. Adiponectin appeared to be a mediator of this association, but circulating biomarkers of inflammation, endothelial dysfunction, and fasting insulin did not explain this association. These results suggest that further research is needed into the potentially mediating roles of other biomarkers affected by alcohol consumption.
We have assembled two junctions that incorporate redox sites between Hg electrodes by different interactions. In the first junction, Hg-SAM-R//R-SAM-Hg, the redox site (R) are covalently linked to each electrode in self assembled monolayers (SAM-R). In the second junction, Hg-SAM//R//SAM-Hg, the redox sites dissolved in solution are trapped by electrostatic interaction at the SAM formed at the electrodes. The current flowing through these junctions can be controlled by adjusting the potential applied at the electrodes with respect to the redox potential of the species by using an electrochemical system. The current flowing in these two junctions is mediated by the redox sites through different mechanisms. In particular, the current flowing through the Hg-SAM-R//R-SAM-Hg junction occurs through a self exchange mechanism between the redox sites organized at each electrode, while the current flowing through the Hg-SAM//R//SAM-Hg junction is dominated by a redox-cycling mechanism. The systems described here are easy to assemble, well-characterized, yield reproducible data and make it easy to modify the electrical properties of the junctions by changing the nature of the redox centres. For these characteristics they are well suited for collecting fundamental information relevant to the fabrication of molecular switches.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharge density wave pinning and disorder in two dimensionsHongjie Dai and Charles M. LieberCite this: J. Phys. Chem. 1993, 97, 10, 2362–2367Publication Date (Print):March 1, 1993Publication History Published online1 May 2002Published inissue 1 March 1993https://pubs.acs.org/doi/10.1021/j100112a042https://doi.org/10.1021/j100112a042research-articleACS PublicationsRequest reuse permissionsArticle Views379Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
Dislocation nucleation from a stressed crack tip is analyzed based on the Peierls concept. A periodic relation between shear stress and atomic shear displacement is assumed to hold along the most highly stressed slip plane emanating from a crack tip. This allows some small slip displacement to occur near the tip in response to small applied loading and, with increase in loading, the incipient dislocation configuration becomes unstable and leads to a fully formed dislocation which is driven away from the crack. An exact solution for the loading at that nucleation instability is developed via the J-integral for the case when the crack and slip planes coincide, and an approximate solution is given when they do not. Solutions are also given for emission of dissociated dislocations, especially partial dislocation pairs in fcc crystals. The level of applied stress intensity factors required for dislocation nucleation is shown to be proportional to √γ us , where γ us , the unstable stacking energy, is a new solid state parameter identified by the analysis. It is the maximum energy encountered in the block-like sliding along a slip plane, in the Burgers vector direction, of one half of a crystal relative to the other. Approximate estimates of γ us are summarized and the results are used to evaluate brittle vs ductile response in fcc and bcc metals in terms of the competition between dislocation nucleation and Griffith cleavage at a crack tip. The predictions seem compatible with known behavior and also show that in many cases solids which are predicted to first cleave under pure mode I loading should instead first emit dislocations when that loading includes very small amounts of mode II and III shear. The analysis in this paper also reveals a feature of the near-tip slip distribution corresponding to the saddle point energy configuration for cracks that are loaded below the nucleation threshold, as is of interest for thermal activation.
Deformation associated with the earthquake cycle in the Shumagin Islands segment of the Alaska‐Aleutian subduction zone is analyzed with the use of a two‐dimensional finite element model. The model consists of an oceanic plate dipping under an upper plate, both of which respond elastically to stress fluctuations in the earthquake cycle, and these are underlain by asthenospheric mantle and mantle wedge regions which respond viscoelastically. It is tailored to the geometry of the Shumagin Islands region, by using seismicity to define the position of the interplate interface and (partially) coupled region along it. The model is preconditioned by forcing this interface to undergo periodically repeated slips up to (and including) the time of the May 31, 1917, event ( M s = 7.4) in that region, with each chosen to be consistent with the moment and estimated rupture area of that event. We investigated the dependence of model results for geodetic signals on the strength of seismic coupling between the plates and viscoelastic relaxation of deviatoric stresses in the mantle, including in the mantle wedge close to the plate junction and along the aseismic downdip continuation of the thrust interface. In models with significant relaxation in the wedge or downdip thrust zone, results show that as the intraseismic stage matures, there is a region of diminished compressional strain rates, and even of locally extensional rates, on the Earth's surface above the downdip end of the seismically coupled zone. Based on the seismic estimates of the location of the coupled zone, this region is in the area of the Shumagin Islands. We find that if approximately 20% of the convergence takes place seismically (compatible with the previous seismic history), and if an extensive region of relaxed deviatoric stress is assumed to be present in the wedge and/or along the downdip interface, then deformations predicted by the model can be made consistent with the measured strain data from the Shumagin Islands geodetic network [ Lisowski et al. , 1988; Larson and Lisowski , 1994], as well as uplift and tilt data [ Savage and Plafker , 1991; Beavan , 1992]. Our model simulations here suggest that the Shumagin segment is capable of large earthquakes. The hypothesis of totally aseismic subduction is not similarly consistent with all geodetic constraints.
