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161.
David H. Lamparelli Alba Villar-Yanez Lorenz Dittrich Jeroen Rintjema Fernando Bravo Carles Bo Arjan W. Kleij 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314659
We here report the organocatalytic and temperature-controlled depolymerization of biobased poly(limonene carbonate) providing access to its trans-configured cyclic carbonate as the major product. The base TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene) offers a unique opportunity to break down polycarbonates via end-group activation or main chain scission pathways as supported by various controls and computational analysis. These energetically competitive processes represent an unprecedented divergent approach to polycarbonate recycling. The trans limonene carbonate can be converted back to its polycarbonate via ring-opening polymerization using the same organocatalyst in the presence of an alcohol initiator, offering thus a potential circular and practical route for polycarbonate recycling. 相似文献
162.
Erik Schwartz Vincenzo Palermo Dr. Chris E. Finlayson Dr. Ya‐Shih Huang Matthijs B. J. Otten Andrea Liscio Dr. Sara Trapani Irene González‐Valls Patrick Brocorens Dr. Jeroen J. L. M. Cornelissen Dr. Kalina Peneva Dr. Klaus Müllen Prof. Dr. Frank C. Spano Prof. Dr. Arkady Yartsev Prof. Sebastian Westenhoff Dr. Richard H. Friend Prof. Dr. David Beljonne Dr. Roeland J. M. Nolte Prof. Dr. Paolo Samorì Prof. Dr. Alan E. Rowan Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(11):2536-2547
Exciton migration! Spectroscopic analyses and extensive molecular dynamics studies revealed a well‐defined 41 helix in which the perylene molecules (see figure) form four “helter‐skelter‐like” overlapping pathways along which excitons and electrons can rapidly migrate.
163.
Leach ES Hopkinson A Franklin K van Duijneveldt JS 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3821-3830
It is shown how stable, nonaqueous suspensions of fully exfoliated smectite clays such as Laponite and montmorillonite can be obtained. Suspensions in toluene and in a branched aliphatic solvent (polydecene) were characterized using elemental analysis, rheometry, and small-angle X-ray scattering. For Laponite, stable suspensions were obtained by adsorbing a dichain poly(isobutylene) based stabilizer to the particles. This approach did not result in full exfoliation for montmorillonite particles, possibly because the stabilizer was able to connect individual clay sheets at the edges during the treatment process. Instead, a quaternary ammonium surfactant, dimethyl dioctadecylammonium bromide (DODAB), was first adsorbed to the clay. Subsequently, adsorption of the poly(isobutylene) based stabilizer to this pretreated clay resulted in fully exfoliated suspensions of montmorillonite. Suspensions of clay particles treated only with DODAB have been studied by several authors before and are included in this study for comparison. A detailed discussion of the suspension behavior of the different clay samples is given. The suspension routes presented here may enable further studies of the structure and flow behavior of suspensions of thin, flexible clay platelets as a function of aspect ratio. 相似文献
164.
Reinout Heijungs Gjalt Huppes Jeroen B. Guinée 《Polymer Degradation and Stability》2010,95(3):422-1719
There are many approaches to study the environmental and sustainability aspects of production and consumption. Some of these reside at the level of concepts, e.g., industrial ecology, design for environment, and cleaner production. Other approaches are based on the use of quantitative models, e.g., life cycle assessment, material flow accounting and strategic environmental assessment. This paper focuses on the development of a framework that is able to incorporate different models for environmental analysis, with the option of a broader scope that also includes economic and social aspects, thus covering the three pillars of sustainability. This framework builds on the ISO-framework for life cycle assessment, but takes a broader view, and allows us to move from micro questions on specific products, via meso questions on life styles up to macro questions in which the entire societal structure is part of the analysis. 相似文献
165.
Jeroen Suijs Peter Borm Herbert Hamers Marieke Quant Maurice Koster 《Annals of Operations Research》2005,137(1):117-140
This paper focuses on sharing the costs and revenues of maintaining a public network communication structure. Revenues are
assumed to be bilateral and communication links are publicly available but costly. It is assumed that agents are located at
the vertices of an undirected graph in which the edges represent all possible communication links. We take the approach from
cooperative game theory and focus on the corresponding network game in coalitional form which relates any coalition of agents
to its highest possible net benefit, i.e., the net benefit corresponding to an optimal operative network. Although finding
an optimal network in general is a difficult problem, it is shown that corresponding network games are (totally) balanced.
In the proof of this result a specific relaxation, duality and techniques of linear production games with committee control
play a role. Sufficient conditions for convexity of network games are derived. Possible extensions of the model and its results
are discussed.
The research of Jeroen Suijs has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences. 相似文献
166.
We generalize the Existential Divisibility Lemma by Th. Pheidas [7] to all global fields K of characteristic not 2, and for all sets of primes that are inert in a quadratic extension L of K. We also remove the conditions in real and ramifying primes, which were present in Pheidas’ version. As a Corollary, we recover
the known fact that the set of integral elements at a prime in a global field is existentially definable. 相似文献
167.
Two Bacterial Diterpene Synthases from Allokutzneria albata Produce Bonnadiene,Phomopsene, and Allokutznerene 下载免费PDF全文
Lukas Lauterbach Jan Rinkel Prof. Dr. Jeroen S. Dickschat 《Angewandte Chemie (International ed. in English)》2018,57(27):8280-8283
Two diterpene synthases from Allokutzneria albata were studied for their products, resulting in the identification of the new compound bonnadiene from the first enzyme. Although phylogenetically unrelated to fungal phomopsene synthase, the second enzyme produced a mixture of phomopsene and a biosynthetically linked new compound, allokutznerene, as well as spiroviolene. Both enzymes were subjected to in‐depth mechanistic studies involving isotopic labelling experiments, metal‐cofactor variation, and site‐directed mutagenesis. Oxidation products of phomopsene and allokutznerene are also discussed. 相似文献
168.
Brereton Richard G. Jansen Jeroen Lopes João Marini Federico Pomerantsev Alexey Rodionova Oxana Roger Jean Michel Walczak Beata Tauler Romà 《Analytical and bioanalytical chemistry》2018,410(26):6691-6704
Analytical and Bioanalytical Chemistry - The contribution of chemometrics to important stages throughout the entire analytical process such as experimental design, sampling, and explorative data... 相似文献
169.
van As BA van Buijtenen J Heise A Broxterman QB Verzijl GK Palmans AR Meijer EW 《Journal of the American Chemical Society》2005,127(28):9964-9965
Iterative tandem catalysis is presented as a flexible tool for obtaining chiral macromolecules from racemic or prochiral monomers. Here, we combine lipase-catalyzed ring-opening of omega-substituted lactones with ruthenium-catalyzed racemization. In a two-pot system, enantioenriched oligomers of 6-methyl-epsilon-caprolactone were synthesized, which could not have been obtained by enzymatic ring-opening alone. A one-pot experiment proved highly promising in developing a novel route toward enantiopure polyesters. 相似文献
170.
The determination of binding constants using surface plasmon resonance (SPR) was introduced to optimise a competitive homogeneous fluorescence energy-transfer immunoassay (ETIA) before labelling. Steroids were chosen as model for the detection of three analytes estrone, estradiol and ethinylestradiol--by taking three polyclonal antibodies (anti estrone-, anti estradiol- and anti estrogen-antibodies) and the corresponding analyte derivatives used for the immunisation. The active concentration of the antibodies was determined before and after labelling. Inhibition curves were recorded using SPR for all possible combinations of analyte, antibody, and analyte derivatives. The experiments revealed that the active antibody concentration can be reduced to 30% whereas the antibody affinity is not affected by the labelling process. Limits of the use of SPR for determination of affinity constants in solution are discussed. All possible ETIA calibration for the quantification of estrone and estradiol was performed. The lower limits of detection for estrone (0.06 microg L(-1)) and estradiol (0.17 microg L(-1)) were reached with the anti-estrogen IgG and its derivative 相似文献