6,726 research outputs found
Synthesis and Characterization of Heterobimetallic Oxo-Bridged Aluminum–Rare Earth Metal Complexes
No full textReaction of the aluminum hydroxide LAl(OH)[C(Ph)CH(Ph)] (1, L = HC[(CMe)(NAr)](2), Ar = 2,6-iPr(2)C(6)H(3)) with Y(CH2SiMe3)(3)(THF)(2) yielded the oxo-bridged heterobimetallic yttrium dialkyl complex LAl[C(Ph)CH(Ph)](mu-O)Y(CH2SiMe3)(2)(THF)(2) (2). Alkane elimination reaction of 2 with 2-(imino)pyrrole [NN]H ([NN]H = 2-(ArN=CH)-5-tBuC(4)H(2)NH) afforded the yttrium monoalkyl complex LAl[C(Ph)CH (Ph)] (mu-O)Y(CH2SiMe3)[NN] (THF)(2) (5). Alternatively, 5 can be prepared in high yield by reaction of 1 with [NN]Y(CH2SiMe3)(2)(THF)(2) (3). The analogous samarium alkyl complex LAl[C(Ph)CH(Ph)](mu-O)Sm(CH2SiMe3)[NN](THF)(2) (6) was prepared similarly. Reactions of 5 and 6 with 1 equiv of iPrOH yielded the corresponding alkoxyl complexes 7 and 8, respectively. The molecular structures of 3, 6, and 8 have been determined by X-ray single-crystal analysis. Complexes 2, 3, 5, 7, and 8 have been investigated as lactide polymerization initiators. The heterobimetallic alkoxyl 8 is highly active to yield high molecular weight (M-n = 6.91 x 10(4)) polylactides with over 91% conversion at the lactide-to-initiator molar ratio of 2000.Deutsche Forschungsgemeinschaf
Samarium-Catalyzed Diastereoselective Double Addition of Phenylphosphine to Imines and Mechanistic Studies by DFT Calculations
No full textbibtex: ISI:000400097100003 bibtex\location:'POSTFACH 101161, 69451 WEINHEIM, GERMANY',publisher:'WILEY-V C H VERLAG GMBH',type:'Article',affiliation:'Cui, CM (Reprint Author), Nankai Univ, State Key Lab Elementoorgan Chem, Collaborat Innovat Ctr Chem Sci & Engn, Tianjin 300071, Peoples R China. Maron, L (Reprint Author), Univ Toulouse, LPCNO, CNRS, INSA,UPS,UMR 5215, 135 Ave Rangueil, F-31077 Toulouse, France. Li, Jianfeng; Song, Changhong; Liu, Jinxi; Fan, Guilan; Cui, Chunming, Nankai Univ, State Key Lab Elementoorgan Chem, Collaborat Innovat Ctr Chem Sci & Engn, Tianjin 300071, Peoples R China. Lamsfus, Carlos Alvarez; Maron, Laurent, Univ Toulouse, LPCNO, CNRS, INSA,UPS,UMR 5215, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET2JI',eissn:'1867-3899','funding-acknowledgement':'National Natural Science Foundation of China [21390401]; Humboldt Foundation; Chinese Academy of Sciences','funding-text':'We are grateful to the National Natural Science Foundation of China (21390401) for financial support. L.M. is a member of the Institut Universitaire de France. The Humboldt Foundation and the Chinese Academy of Sciences are acknowledged for financial support of this work. L.M. and C.A.L. are grateful to CalMip for the generous grant of computing time.','journal-iso':'ChemCatChem','keywords-plus':'H BOND ADDITION; AMINOPHOSPHINE LIGANDS; ASYMMETRIC ADDITION; CHIRAL 3,4-DIAZAPHOSPHOLANES; ALPHA-AMINOPHOSPHINES; EFFICIENT SYNTHESIS; METAL-COMPLEXES; HYDROPHOSPHINATION; ALKENES; CARBODIIMIDES','number-of-cited-references':'48','orcid-numbers':'Alvarez Lamsfus, Carlos/0000-0002-4442-7052','research-areas':'Chemistry','times-cited':'2','unique-id':'ISI:000400097100003','usage-count-last-180-days':'4','usage-count-since-2013':'13','web-of-science-categories':'Chemistry, Physical'\International audienceThe catalytic hydrophosphination of imines represents the most straightforward and atom-economical strategy for the preparation of alpha-aminophosphines, which are useful as biologically active molecules and ligands for catalysis. The first catalytic protocol for the rapid and high-yielding hydrophosphination of common imines enabled by an ene-diamido samarium methoxide catalyst was developed. The reaction allowed the efficient and diastereoselective synthesis of various bis(alpha-amino)phosphines through the double addition of PhPH2 to common imines. The catalytic reaction has a relatively wide substrate scope and offers high diastereoselectivities (up to 99: 1 dr for meso products) and high yields (up to 97%). DFT calculations disclosed an inner-sphere mechanism involving unprecedented activation of a Sm-O bond by a phosphine and stabilization of the addition intermediates by the metal center
Native p-type transparent conductive CuI via intrinsic defects
No full textThe ability of CuI to be doped p-type via the introduction of native defects has been investigated using first-principles pseudopotential calculations based on density functional theory. The Cu vacancy has a lower formation energy than any of the other native defects, which include I vacancy (V(I)), Cu interstitial (Cu(i)), I interstitial (I(i)), Cu antisite (Cu(I)), and I antisite (I(Cu)). Combined with its shallow acceptor level, it offers sufficient hole concentrations in CuI. The natural band alignments as compared to zinc-blende ZnS, ZnSe, and ZnTe have also been calculated in order to further identify the p-type dopability of CuI. It is found that CuI has a relatively high valence band maximum and conduction band minimum, which also makes it easy to dope CuI p-type in terms of the doping limit rule. In addition, the small effective mass of the light hole-about 0.303m(0)-can provide high mobility and p-type conductivity in CuI. All of these results make CuI an ideal candidate for native p-type materials (C) 2011 American Institute of Physics. [doi:10.1063/1.3633220
Samarium-Catalyzed Diastereoselective Double Addition of Phenylphosphine to Imines and Mechanistic Studies by DFT Calculations
No full textbibtex: ISI:000400097100003 bibtex\location:'POSTFACH 101161, 69451 WEINHEIM, GERMANY',publisher:'WILEY-V C H VERLAG GMBH',type:'Article',affiliation:'Cui, CM (Reprint Author), Nankai Univ, State Key Lab Elementoorgan Chem, Collaborat Innovat Ctr Chem Sci & Engn, Tianjin 300071, Peoples R China. Maron, L (Reprint Author), Univ Toulouse, LPCNO, CNRS, INSA,UPS,UMR 5215, 135 Ave Rangueil, F-31077 Toulouse, France. Li, Jianfeng; Song, Changhong; Liu, Jinxi; Fan, Guilan; Cui, Chunming, Nankai Univ, State Key Lab Elementoorgan Chem, Collaborat Innovat Ctr Chem Sci & Engn, Tianjin 300071, Peoples R China. Lamsfus, Carlos Alvarez; Maron, Laurent, Univ Toulouse, LPCNO, CNRS, INSA,UPS,UMR 5215, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET2JI',eissn:'1867-3899','funding-acknowledgement':'National Natural Science Foundation of China [21390401]; Humboldt Foundation; Chinese Academy of Sciences','funding-text':'We are grateful to the National Natural Science Foundation of China (21390401) for financial support. L.M. is a member of the Institut Universitaire de France. The Humboldt Foundation and the Chinese Academy of Sciences are acknowledged for financial support of this work. L.M. and C.A.L. are grateful to CalMip for the generous grant of computing time.','journal-iso':'ChemCatChem','keywords-plus':'H BOND ADDITION; AMINOPHOSPHINE LIGANDS; ASYMMETRIC ADDITION; CHIRAL 3,4-DIAZAPHOSPHOLANES; ALPHA-AMINOPHOSPHINES; EFFICIENT SYNTHESIS; METAL-COMPLEXES; HYDROPHOSPHINATION; ALKENES; CARBODIIMIDES','number-of-cited-references':'48','orcid-numbers':'Alvarez Lamsfus, Carlos/0000-0002-4442-7052','research-areas':'Chemistry','times-cited':'2','unique-id':'ISI:000400097100003','usage-count-last-180-days':'4','usage-count-since-2013':'13','web-of-science-categories':'Chemistry, Physical'\International audienceThe catalytic hydrophosphination of imines represents the most straightforward and atom-economical strategy for the preparation of alpha-aminophosphines, which are useful as biologically active molecules and ligands for catalysis. The first catalytic protocol for the rapid and high-yielding hydrophosphination of common imines enabled by an ene-diamido samarium methoxide catalyst was developed. The reaction allowed the efficient and diastereoselective synthesis of various bis(alpha-amino)phosphines through the double addition of PhPH2 to common imines. The catalytic reaction has a relatively wide substrate scope and offers high diastereoselectivities (up to 99: 1 dr for meso products) and high yields (up to 97%). DFT calculations disclosed an inner-sphere mechanism involving unprecedented activation of a Sm-O bond by a phosphine and stabilization of the addition intermediates by the metal center
Youthhood
No full textTESTING-GROUND issue 03, Youthhood, examines worlds through youthful eyes, makes evident young ambitions, and questions how we can better empower young people to design cities, landscapes, and a planet that works for them. The issue includes contributions from: Carmel Keren, Jude Daniel Smith, Claire Edwards, Kazeem Kuteyi, Emmanuel Adarkwah, Reza Nik, Dan Cui, Kristofer Cullum-Fernandez, Fida Sassi, Simeon Shtebunaev, Daze Aghaji, Averill Dimabuyu, Sarri Elfaitouri, Rebecca McDonald-Balfour, and Ed Wall.
Rebecca McDonald-Balfour (Author), Jude Daniel Smith (Author), Daze Aghaji (Author), Carmel Keran (Author), Alexis Liu (Author), Dan Cui (Author), Kristofer Cullum-Fernandez (Author), Fida Sassi (Author), Averill Dimabuyu (Author), Ed
Impact damage of composite laminates with high-speed waterjet
No full textRain erosion may cause substantial damage to aircrafts during supersonic flight. Such event is investigated here via high-speed waterjet impact on composite laminates. An experimental setup is developed to produce waterjets with the speed up to 700m/s and a finite element model of the waterjet-composite impact event is established. The consistency of experiment and simulation results validates the adopted numerical methods. The distribution of the water-hammer pressure is non-uniform and the maximum pressure occurs near the contact periphery when the water is about to eject laterally. After a high-speed (300∼560m/s) waterjet impacts a composite laminate, the impacted surface depression is observed, and the typical surface damage presents a central region with no visible surface damage surrounded by a faded “failure ring” with resin removal, matrix cracking and minor fiber fracture. Delamination occurs at the interfaces of adjacent layers with unequal dimensions and longitudinal matrix cracking appears on the back surface. Both the velocity and the diameter of waterjets are crucial factors on CFRP damage extents. Water-hammer pressure, the stagnation pressure and propagation of stress waves are failure mechanisms for most matrix damage in CFRP impacted by waterjets.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Sampling and Reconstruction of Signals on Product Graphs
No full textIn this paper, we consider the problem of subsampling and reconstruction of signals that reside on the vertices of a product graph, such as sensor network time series, genomic signals, or product ratings in a social network. Specifically, we leverage the product structure of the underlying domain and sample nodes from the graph factors. The proposed scheme is particularly useful for processing signals on large-scale product graphs. The sampling sets are designed using a low-complexity greedy algorithm and can be proven to be near-optimal. To illustrate the developed theory, numerical experiments based on real datasets are provided for sampling 3D dynamic point clouds and for active learning in recommender systems.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
Ban dao ti yi zhi jie gou zai guang cui hua he guang dian cui hua zhong de yan jiu
No full textLi, Qian = 半導體异质结构在光催化和光電催化中的研究 / 李乾.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 145-162).Abstracts also in Chinese.Title from PDF title page (viewed on 30, December, 2016).Li, Qian = Ban dao ti yi zhi jie gou zai guang cui hua he guang dian cui hua zhong de yan jiu / Li Qian
A Conversational User Interface for Instructional Maintenance Reports
No full textMaintaining a complex system, such as a modern production line, is a knowledge-intensive task. Many firms use maintenance reports as a decision support tool. However, reports are often poor quality and tedious to compile. A Conversational User Interface (CUI) could streamline the reporting process by validating the user's input, eliciting more valuable information, and reducing the time needed. In this paper, we use a Technology Probe to explore the potential of a CUI to create instructional maintenance reports. We conducted a between-groups study (N = 24) in which participants had to replace the inner tube of a bicycle tire. One group documented the procedure using a CUI while replacing the inner tube, whereas the other group compiled a paper report afterward. The CUI was enacted by a researcher according to a set of rules. Our results indicate that using a CUI for maintenance reports saves a significant amount of time, is no more cognitively demanding than writing a report, and results in maintenance reports of higher quality. Internet of ThingsHuman-Centred Artificial Intelligenc
The Logic of Knowledge-Based Cooperation in the Social Dilemma
No full textComputer Science, Artificial IntelligenceComputer Science, Theory & MethodsCPCI-S(ISTP)
- …
