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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
A long-standing limitation of first-principles calculations of substitutional alloy phase diagrams is the difficulty in accounting for lattice vibrations. A survey of the theoretical and experimental literature seeking to quantify the effect of lattice vibrations on phase stability indicates that they can be significant. Typical vibrational entropy differences between phases are of the order of 0.1 to 0.2kB/atom, which is comparable to the typical values of configurational entropy differences in binary alloys (at most 0.693kB/atom). This article presents the basic formalism underlying ab initio phase diagram calculations, along with the generalization required to account for lattice vibrations. The authors review the various techniques allowing the theoretical calculation and the experimental determination of phonon dispersion curves and related thermodynamic quantities, such as vibrational entropy or free energy. A clear picture of the origin of vibrational entropy differences between phases in an alloy system is presented that goes beyond the traditional bond counting and volume change arguments. Vibrational entropy change can be attributed to the changes in chemical bond stiffness associated with the changes in bond length that take place during a phase transformation. This so-called “bond stiffness vs bond length” interpretation both summarizes the key phenomenon driving vibrational entropy changes and provides a practical tool to model them.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract The linear response of a selected arch dam to harmonic upstream, vertical or cross‐stream ground motion is presented for a wide range of the important system parameters characterizing the properties of the dam, foundation rock, impounded water and reservoir boundary materials. Based on these frequency‐response functions, the dam‐foundation rock interaction effects in the dynamic response of arch dams are investigated.
There is an increasing conflict between business incentives to hide models and data as trade secrets, and the societal need for algorithmic transparency. For example, a rightsholder wishing to know whether their copyrighted works have been used during training must convince the model provider to allow a third party to audit the model and data. Finding a mutually agreeable third party is difficult, and the associated costs often make this approach impractical. In this work, we show that it is possible to simultaneously allow model providers to keep their model weights (but not architecture) and data secret while allowing other parties to trustlessly audit model and data properties. We do this by designing a protocol called ZkAudit in which model providers publish cryptographic commitments of datasets and model weights, alongside a zero-knowledge proof (ZKP) certifying that published commitments are derived from training the model. Model providers can then respond to audit requests by privately computing any function F of the dataset (or model) and releasing the output of F alongside another ZKP certifying the correct execution of F. To enable ZkAudit, we develop new methods of computing ZKPs for SGD on modern neural nets for simple recommender systems and image classification models capable of high accuracies on ImageNet. Empirically, we show it is possible to provide trustless audits of DNNs, including copyright, censorship, and counterfactual audits with little to no loss in accuracy.
No abstract is provided for this article.
A large acceleration of carbon−nitrogen bond-forming reductive elimination from heteroarylpalladium amido complexes by addition of Lewis acids is described. Several lines of data imply that this effect arises from coordination of the Lewis acid to the nitrogen of the heteroaryl group. The presence of this coordination was confirmed by isolation of a Lewis acid base complex with a borane coordinated to the pyridyl nitrogen. This adduct underwent reductive elimination faster than the complex lacking the Lewis acid, and it occurred in high yield. Control experiments showed that this acceleration of reductive elimination was not observed for the reactions of arylpalladium amide complexes. This effect of Lewis acids translated to catalytic C−N bond-forming coupling processes. The binding of Lewis acids to the pyridyl nitrogen led to an acceleration of the amidation of unactivated heteroaryl bromides catalyzed by palladium complexes of Xantphos. The rates were faster and the yields were higher for reactions of BEt3 adducts of basic heteroaryl bromides than for the free heteroaryl bromides. This phenomenon draws parallels to the beneficial effect of Lewis acids on the reductive elimination of nitriles from arylmetal cyanide complexes and the catalytic hydrocyanation of olefins.
Few readers of this journal will have failed to notice the recent uproar, particularly in Great Britain, concerning the release of genetically modified organisms (GMOs). In response to the demands of activists, European governments have restricted the import and release of GMOs, and activists here
ADVERTISEMENT RETURN TO ISSUEPREVArticleMolecular dynamics study of methane and xenon in silicalite [Erratum to document cited in CA113(20):183284q]R. Larry June, Alexis T. Bell, and Doros N. TheodorouCite this: J. Phys. Chem. 1991, 95, 2, 1014Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/j100155a098https://doi.org/10.1021/j100155a098research-articleACS PublicationsRequest reuse permissionsArticle Views41Altmetric-Citations4LEARN 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
