6,332 publications from this institution
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe reduction by deuterium on platinum black of exo-2-norbornyl* and endo-2-norbornyl* to norbornane-2-d1 occurs with predominant retention of configurationT. Randall Lee and George M. WhitesidesCite this: J. Am. Chem. Soc. 1991, 113, 1, 368–369Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/ja00001a058https://doi.org/10.1021/ja00001a058research-articleACS PublicationsRequest reuse permissionsArticle Views82Altmetric-Citations3LEARN 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 optionsGet e-Alertsclose Get e-Alerts
Abstract : This paper presents calculations of the temperature elevations accompanying rapid plastic deformation near a crack tip. Solutions for the stress and strain distribution in non-hardening materials are employed as a basis for the heating rate distribution. Results are approximate in that temperature independent mechanical and thermal properties are assumed and thermal stressing is neglected. Two cases are considered: a stationary crack under increasing load, and a running crack with locally constant speed and plastic zone size. Numerical results are presented as based on properties of 2024 aluminum alloy, 6Al-4V titanium alloy, and mild steel. Temperature rises predicted for test conditions on these metals seldom exceed 100C. This may, nevertheless, be large enough to influence fracture and to account for the observed rise in roughness at very fast rates. Consequences are examined for the assumption that the localized tip temperature elevation alone governs fracture toughness at very fast rates. (Author)
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnzyme-catalyzed organic synthesis: regeneration of deuterated nicotinamide cofactors for use in large-scale enzymatic synthesis of deuterated substancesChi Huey Wong and George M. WhitesidesCite this: J. Am. Chem. Soc. 1983, 105, 15, 5012–5014Publication Date (Print):July 1, 1983Publication History Published online1 May 2002Published inissue 1 July 1983https://pubs.acs.org/doi/10.1021/ja00353a026https://doi.org/10.1021/ja00353a026research-articleACS PublicationsRequest reuse permissionsArticle Views543Altmetric-Citations64LEARN 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 optionsGet e-Alertsclose Get e-Alerts
This paper describes the oriented nucleation of calcite controlled by self-assembled monolayers (SAMs) of ω-terminated alkanethiols (HS(CH2)nX) supported on metal films. The effect of the chemistry and geometry of the organic surfaces was surveyed by using different functional groups (X = CO2-, SO3-, PO32-, OH, N(CH3)3+, CH3) and different supporting metals (Au and Ag). Optical microscopy, SEM with image analysis, and XRD were employed to characterize density and orientation of the crystals. Compared to the control surfaces of bare metal films, SAMs terminated in CO2-, SO3-, PO32-, and OH groups were more active in inducing nucleation, whereas SAMs terminated in N(CH3)3+ and CH3 inhibited nucleation. The crystallographic orientations of the crystals were distinct and highly homogeneous for each surface, but different on different surfaces. SAMs of CO2-/Au, CO2-/Ag, OH/Au, OH/Ag, SO3-/Au, and SO3-/Ag induced the face-selective nucleation of calcite from the (015), (012), (104), (103), (1 0 12), and (107) crystallographic planes, respectively. SAMs of PO32-/Au and PO32-/Ag were specific for a family of planes that form an angle of 24° and 40° with the c-axis, respectively. The high degree of orientational uniformity of the overgrown crystals (97−100% oriented crystals for well-ordered SAMs) and the decrease of uniformity as the defect density in the SAMs increased imply that nucleation takes place from the oriented, homogeneous SAM and that the specific interfacial structure is controlling orientation of crystal growth. The possible correlation between the differences in the structure of SAMs supported on Au and Ag and the orientation of the incipient crystals is discussed. Varying the geometry, chemistry, and pattern of the functional groups on SAMs provides, therefore, a tool for a fine-tuning of the orientation of crystal growth and for the formation of high-resolution patterns of oriented crystals.
Computational science's driving force has been and will continue to be the steady and rapid growth in available raw computing power. This growth exceeds anything else witnessed in the history of technology. The challenge for the 21st Century is to exploit properly this enormous potential. Several fairly obvious directions of development can (and do) present great technical challenges, but the author's focus is on the less obvious challenges. He considers multiphysics phenomena, software validation, multiscale phenomena and computational intelligence.
Abstract Das Alkyl‐Hg(II)‐bromid (I) reagiert mit Na‐tetrahydridoborat in N,N‐Dimethylformamid (DMF) in Gegenwart von Sauerstoff zu den Produkten (II) bis (IV).
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFumarase-catalyzed synthesis of L-threo-chloromalic acid and its conversion to 2-deoxy-D-ribose and D-erythro-sphingosineMark A. Findeis and George M. WhitesidesCite this: J. Org. Chem. 1987, 52, 13, 2838–2848Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 1987https://pubs.acs.org/doi/10.1021/jo00389a035https://doi.org/10.1021/jo00389a035research-articleACS PublicationsRequest reuse permissionsArticle Views362Altmetric-Citations56LEARN 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 optionsGet e-Alertsclose Get e-Alerts