pinecone/core-2020-05-10-deduplication huggingface dataset:
Ceria-Zirconia Particles Wrapped in a 2D Carbon Envelope: Improved Low-Temperature Oxygen Transfer and Oxidation Activity

Engineering the interface between different components of heterogeneous catalysts at nanometer level can radically alter their performances. This is particularly true for ceria-based catalysts where the interactions are critical for obtaining materials with enhanced properties. Here we show that mechanical contact achieved by high-energy milling of CeO2 -ZrO2 powders and carbon soot results in the formation of a core of oxide particles wrapped in a thin carbon envelope. This 2D nanoscale carbon arrangement greatly increases the number and quality of contact points between the oxide and carbon. Consequently, the temperatures of activation and transfer of the oxygen in ceria are shifted to exceptionally low temperatures and the soot combustion rate is boosted. The study confirms the importance of the redox behavior of ceria-zirconia particles in the mechanism of soot oxidation and shows that the organization of contact points at the nanoscale can significantly modify the reactivity resulting in unexpected properties and functionalities
Ceria-zirconia particles wrapped in a 2D carbon envelope: improved low-temperature oxygen transfer and oxidation activity

Engineering the interface between different compo-nents of heterogeneous catalysts at nanometer level canradically alter their performances.This is particularly true forceria-based catalysts where the interactions are critical forobtaining materials with enhanced properties.Here we showthat mechanical contact achieved by high-energy milling ofCeO2–ZrO2powders and carbon soot results in the formationof acore of oxide particles wrapped in athin carbon envelope.This 2D nanoscale carbon arrangement greatly increases thenumber and quality of contact points between the oxide andcarbon. Consequently,the temperatures of activation andtransfer of the oxygen in ceria are shifted to exceptionally lowtemperatures and the soot combustion rate is boosted. Thestudy confirms the importance of the redox behavior of ceria-zirconia particles in the mechanism of soot oxidation andshows that the organization of contact points at the nanoscalecan significantly modify the reactivity resulting in unexpectedproperties and functionalities.Postprint (published version
MiniAp-4: A Venom-Inspired Peptidomimetic for Brain Delivery

Drug delivery across the blood-brain barrier (BBB) is a formidable challenge for therapies targeting the central nervous system. Although BBB shuttle peptides enhance transport into the brain non-invasively, their application is partly limited by lability to proteases. The present study proposes the use of cyclic peptides derived from venoms as an affordable way to circumvent this drawback. Apamin, a neurotoxin from bee venom, was minimized by reducing its complexity, toxicity, and immunogenicity, while preserving brain targeting, active transport, and protease resistance. Among the analogues designed, the monocyclic lactam-bridged peptidomimetic MiniAp-4 was the most permeable. This molecule is capable of translocating proteins and nanoparticles in a human-cell-based BBB model. Furthermore, MiniAp-4 can efficiently deliver a cargo across the BBB into the brain parenchyma of mice
A general method for extracting individual coupling constants from crowded 1H NMR spectra

Couplings between protons, whether scalar or dipolar, provide a wealth of structural information. Unfortunately, the high number of 1H-1H couplings gives rise to complex multiplets and severe overlap in crowded spectra, greatly complicating their measurement. Many different methods exist for disentangling couplings, but none approaches optimum resolution. Here, we present a general new 2D J-resolved method, PSYCHEDELIC, in which all homonuclear couplings are suppressed in F2, and only the couplings to chosen spins appear, as simple doublets, in F1. This approaches the theoretical limit for resolving 1H-1H couplings, with close to natural linewidths and with only chemical shifts in F2. With the same high sensitivity and spectral purity as the parent PSYCHE pure shift experiment, PSYCHEDELIC offers a robust method for chemists seeking to exploit couplings for structural, conformational, or stereochemical analyses
Sulfur-limonene polysulfide: a material synthesized entirely from industrial by-products and its use in removing toxic metals from water and soil

Published online: October 20, 2015A polysulfide material was synthesized by the direct reaction of sulfur and d-limonene, by-products of the petroleum and citrus industries, respectively. The resulting material was processed into functional coatings or molded into solid devices for the removal of palladium and mercury salts from water and soil. The binding of mercury(II) to the sulfur-limonene polysulfide resulted in a color change. These properties motivate application in next-generation environmental remediation and mercury sensing.Michael P. Crockett, Austin M. Evans, Max J. H. Worthington, Inês S. Albuquerque, Ashley D. Slattery, Christopher T. Gibson, Jonathan A. Campbell, David A. Lewis, Gonçalo J. L. Bernardes, Justin M. Chalke
Role of the Symmetry of Multipoint Hydrogen Bonding on Chelate Cooperativity in Supramolecular Macrocyclization Processes

This is the accepted version of the following article: Angewandte Chemie International Edition 55.1 (2016): 223-227, which has been published in final form at http://dx.doi.org/10.1002/anie.201508854Herein, we analyze the intrinsic chelate effect that multipoint H-bonding patterns exert on the overall energy of dinucleoside cyclic systems. Our results indicate that the chelate effect is regulated by the symmetry of the H-bonding pattern, and that the effective molarity is reduced by about three orders of magnitude when going from the unsymmetric ADD-DAA or DDA-AAD patterns to the symmetric DAD-ADA patternFunding from the European Union (ERC-Starting Grant 279548) and MINECO (CTQ2011-23659 and CTQ2014-57729-P) is gratefully acknowledge
Transfer hydrosilylation

Transfer hydrogenation is without question a common technology in industry and academia. Unlike its countless varieties, conceptually related transfer hydrosilylations had essentially been unreported until the recent development of a radical and an ionic variant. The new methods are both based on a silicon-substituted cyclohexa-1,4-diene and hinge on the aromatization of the corresponding cyclohexadienyl radical and cation intermediates, respectively, concomitant with homo-or heterolytic fission of the Si-C bond. Both the radical and ionic transfer hydrosilylation are brought into context with one other in this Minireview, and early insight into the possibility of transfer hydrosilylation is included. Although the current state-of-the-art is certainly still limited, the recent advances have already revealed the promising potential of transfer hydrosilylation
Experimental and Computational Analysis of the Solvent-Dependent O2/Li+-O2− Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium-Oxygen Batteries

Understanding and controlling the kinetics of O[subscript 2] reduction in the presence of Li+-containing aprotic solvents, to either Li+-O[subscript 2]− by one-electron reduction or Li[subscript 2]O[subscript 2] by two-electron reduction, is instrumental to enhance the discharge voltage and capacity of aprotic Li-O[subscript 2] batteries. Standard potentials of O[subscript 2]/Li+-O[subscript 2]− and O[subscript 2]/O[subscript 2]− were experimentally measured and computed using a mixed cluster-continuum model of ion solvation. Increasing combined solvation of Li+ and O[subscript 2]− was found to lower the coupling of Li+-O[subscript 2]− and the difference between O[subscript 2]/Li+-O[subscript 2]− and O[subscript 2]/O[subscript 2]− potentials. The solvation energy of Li+ trended with donor number (DN), and varied greater than that of O[subscript 2]− ions, which correlated with acceptor number (AN), explaining a previously reported correlation between Li+-O[subscript 2]− solubility and DN. These results highlight the importance of the interplay between ion–solvent and ion–ion interactions for manipulating the energetics of intermediate species produced in aprotic metal–oxygen batteries.National Science Foundation (U.S.) (NSF award no. ECS-0335765)China Clean Energy Research Center-Clean Vehicles Consortium (CERC-CVC)United States. Dept. of Energy (Award number DEPI0000012)National Science Foundation (U.S.) (Award number DMR-0819762)Robert Bosch GmbH (Bosch Energy Research Network (BERN) Grant)Skolkovo Institute of Science and Technology (Skoltech-MIT Center for Electochemical Energy Storage
Polymeric Nanoparticles Amenable to Simultaneous Installation of Exterior Targeting and Interior Therapeutic Proteins

Effective delivery of therapeutic proteins is a formidable challenge. Herein, using a unique polymer family with a wide-ranging set of cationic and hydrophobic features, we developed a novel nanoparticle (NP) platform capable of installing protein ligands on the particle surface and simultaneously carrying therapeutic proteins inside by a self-assembly procedure. The loaded therapeutic proteins (e.g., insulin) within the NPs exhibited sustained and tunable release, while the surface-coated protein ligands (e.g., transferrin) were demonstrated to alter the NP cellular behaviors. In vivo results revealed that the transferrin-coated NPs can effectively be transported across the intestinal epithelium for oral insulin delivery, leading to a notable hypoglycemic response.National Institutes of Health (U.S.) (Grants EB015419, R00CA160350, and CA151884)Prostate Cancer Foundation (Challenge Award)National Research Foundation of Korea (Grant  K1A1A2048701)David H. Koch Institute for Integrative Cancer Research at MIT. Prostate Cancer Foundation Program in Cancer NanotherapeuticsNational Natural Science Foundation (China) (Grant 81173010
Intermolecular electronic coupling of organic units for efficient persistent room-temperature phosphorescence.

Although persistent room-temperature phosphorescence (RTP) emission has been observed for a few pure crystalline organic molecules, there is no consistent mechanism and no universal design strategy for organic persistent RTP (pRTP) materials. A new mechanism for pRTP is presented, based on combining the advantages of different excited-state configurations in coupled intermolecular units, which may be applicable to a wide range of organic molecules. By following this mechanism, we have developed a successful design strategy to obtain bright pRTP by utilizing a heavy halogen atom to further increase the intersystem crossing rate of the coupled units. RTP with a remarkably long lifetime of 0.28 s and a very high quantum efficiency of 5 % was thus obtained under ambient conditions. This strategy represents an important step in the understanding of organic pRTP emission
Two-Dimensional Nanoporous Networks Formed by Liquid-to-Solid Transfer of Hydrogen-Bonded Macrocycles Built from DNA Bases

This is the peer reviewed version of the following article: Angewandte Chemie 128.2 (2016): 669–673, which has been published in final form at http://dx.doi.org/10.1002/anie.201509233. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingWe present an approach that makes use of DNA base pairing to produce hydrogen-bonded macrocycles whose supramolecular structure can be transferred from solution to a solid substrate. A hierarchical assembly process ultimately leads to two-dimensional nanostructured porous networks that are able to host size-complementary guests. DNA base pairing is used to produce hydrogen-bonded macrocycles whose supramolecular structure can be transferred from solution to a solid substrate. A hierarchical assembly process ultimately leads to two-dimensional nanostructured porous networks that are able to host size-complementary guestsFunding from the E.U. (ERC-Starting Grant 279548), MICINN (CTQ2014-57729-P), Fund for Scientific Research – Flanders, KU Leuven (GOA 11/003), Belgian Federal Science Policy Office (IAP-7/05), and the European Research Council under the FP7/2007-2013 / ERC Grant Agreement no. 34032
An Amidinohydrolase Provides the Missing Link in the Biosynthesis of Amino Marginolactone Antibiotics

Desertomycin A is an aminopolyol polyketide containing a macrolactone ring. We have proposed that desertomycin A and similar compounds (marginolactones) are formed by polyketide synthases primed not with gamma-aminobutanoyl-CoA but with 4-guanidinylbutanoyl-CoA, to avoid facile cyclization of the starter unit. This hypothesis requires that there be a final-stage de-amidination of the corresponding guanidino-substituted natural product, but no enzyme for such a process has been described. We have now identified candidate amidinohydrolase genes within the desertomycin and primycin clusters. Deletion of the putative desertomycin amidinohydrolase gene dstH in Streptomyces macronensis led to the accumulation of desertomycin B, the guanidino form of the antibiotic. Also, purified DstH efficiently catalyzed the in vitro conversion of desertomycin B into the A form. Hence this amidinohydrolase furnishes the missing link in this proposed naturally evolved example of protective-group chemistry.BBSRC/BB/J007250/1BBSRC/BB/K002341/
A computational and experimental approach linking disorder, high-pressure behavior, and mechanical properties in UiO frameworks

Whilst many metal–organic frameworks possess the chemical stability needed to be used as functional materials, they often lack the physical strength required for industrial applications. Herein, we have investigated the mechanical properties of two UiO-topology Zr-MOFs, the planar UiO-67 ([Zr6O4(OH)4(bpdc)6], bpdc: 4,4′-biphenyl dicarboxylate) and UiO-abdc ([Zr6O4(OH)4(abdc)6], abdc: 4,4′-azobenzene dicarboxylate) by single-crystal nanoindentation, high-pressure X-ray diffraction, density functional theory calculations, and first-principles molecular dynamics. On increasing pressure, both UiO-67 and UiO-abdc were found to be incompressible when filled with methanol molecules within a diamond anvil cell. Stabilization in both cases is attributed to dynamical linker disorder. The diazo-linker of UiO-abdc possesses local site disorder, which, in conjunction with its longer nature, also decreases the capacity of the framework to compress and stabilizes it against direct compression, compared to UiO-67, characterized by a large elastic modulus. The use of non-linear linkers in the synthesis of UiO-MOFs therefore creates MOFs that have more rigid mechanical properties over a larger pressure range
Solution layer deposition: A technique for the growth of ultra-pure manganese oxides on silica at room temperature

With the ever increasing miniaturization in microelectronic devices, new deposition techniques are required to form high-purity metal oxide layers. Herein, we report a liquid route to specifically produce thin and conformal amorphous manganese oxide layers on silicon substrate, which can be transformed into a manganese silicate layer. The undesired insertion of carbon into the functional layers is avoided through a solution metal–organic chemistry approach named Solution Layer Deposition (SLD). The growth of a pure manganese oxide film by SLD takes place through the decoordination of ligands from a metal–organic complex in mild conditions, and coordination of the resulting metal atoms on a silica surface. The mechanism of this chemical liquid route has been elucidated by solid-state 29Si MAS NMR, XPS, SIMS, and HRTEM
Increasing Electron Transfer Rates with Increasing Donor-Acceptor Distance

Electron transfer can readily occur over long (≥15 Å) distances. Usually reaction rates decrease with increasing distance between donors and acceptors, but theory predicts a regime in which electron-transfer rates increase with increasing donor–acceptor separation. This counter-intuitive behavior can result from the interplay of reorganization energy and electronic coupling, but until now experimental studies have failed to provide unambiguous evidence for this effect. We report here on a homologous series of rigid rodlike donor-bridge-acceptor compounds in which the electron-transfer rate increases by a factor of 8 when the donor–acceptor distance is extended from 22.0 to 30.6 Å, and then it decreases by a factor of 188 when the distance is increased further to 39.2 Å. This effect has important implications for solar energy conversion
Monitoring Backbone Hydrogen-Bond Formation in β-Barrel Membrane Protein Folding

β-barrel membrane proteins are key components of the outer membrane of bacteria, mitochondria and chloroplasts. Their three-dimensional structure is defined by a network of backbone hydrogen bonds between adjacent β-strands. Here, we employ hydrogen-deuterium (H/D) exchange in combination with NMR spectroscopy and mass spectrometry to monitor backbone hydrogen bond formation during folding of the outer membrane protein X (OmpX) from E. coli in detergent micelles. Residue-specific kinetics of interstrand hydrogen-bond formation were found to be uniform in the entire β-barrel and synchronized to formation of the tertiary structure. OmpX folding thus propagates via a long-lived conformational ensemble state in which all backbone amide protons exchange with the solvent and engage in hydrogen bonds only transiently. Stable formation of the entire OmpX hydrogen bond network occurs downhill of the rate-limiting transition state and thus appears cooperative on the overall folding time scale
Synthesis, separation, and characterization of small and highly fluorescent nitrogen-doped carbon nanodots

A facile bottom-up approach to carbon nanodots (CNDs) is reported, using a microwave-assisted procedure under controlled conditions. The as-prepared nitrogen-doped CNDs (NCNDs) show narrow size-distribution, abundant surface traps and functional groups, resulting in tunable fluorescent emission and excellent solubility in water. Moreover, we present a general method for the separation of NCNDs by low-pressure size-exclusion chromatography, leading to an even narrower size distribution, different surface composition, and optical properties. They display among the smallest size and the highest FLQYs reported so far. 13C-enriched starting materials produced N13CNDs suitable for thorough NMR studies, which gave useful information on their molecular structure. Moreover, they can be easily functionalized and can be used as water-soluble carriers. This work provides an avenue to size- and surface-controllable and structurally defined NCNDs for applications in areas such as optoelectronics, biomedicine, and bioimaging
Paving the way for lignin valorisation: recent advances in bioengineering, biorefining and catalysis

© 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine-tuning of multiple “upstream” (i.e., lignin bioengineering, lignin isolation and “early-stage catalytic conversion of lignin”) and “downstream” (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a “beginning-to-end” analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignins biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance
A Potent Glucose-Platinum Conjugate Exploits Glucose Transporters and Preferentially Accumulates in Cancer Cells

Three rationally designed glucose–platinum conjugates (Glc–Pts) were synthesized and their biological activities evaluated. The Glc–Pts, 1–3, exhibit high levels of cytotoxicity toward a panel of cancer cells. The subcellular target and cellular uptake mechanism of the Glc–Pts were elucidated. For uptake into cells, Glc–Pt 1 exploits both glucose and organic cation transporters, both widely overexpressed in cancer. Compound 1 preferentially accumulates in and annihilates cancer, compared to normal epithelial, cells in vitro.National Cancer Institute (U.S.) (CA034992
Azulenesulfonium salts:accessible, stable, and versatile reagents for cross-coupling

Azulenesulfonium salts may be readily prepared from the corresponding azulenes by an SEAr reaction. These azulene sulfonium salts are bench-stable species that may be employed as pseudohalides for cross-coupling. Specifically, their application in Suzuki-Miyaura reactions has been demonstrated with a diverse selection of coupling partners. These azulenesulfonium salts possess significant advantages in comparison with the corresponding azulenyl halides, which are known to be unstable and difficult to prepare in pure form
Targeted synthesis of two super-complex zeolites with embedded isoreticular structures

A novel structural coding approach combining structure solution, prediction, and the targeted synthesis of new zeolites with expanding complexity and embedded isoreticular structures was recently proposed. Using this approach, the structures of two new zeolites in the RHO family, PST-20 and PST-25, were predicted and synthesized. Herein, by extending this approach, the next two higher generation members of this family, PST-26 and PST-28, have been predicted and synthesized. These two zeolites have much larger unit cell volumes (422 655 Å3 and 614 912 Å3, respectively) than those of the lower generations. Their crystallization was confirmed by a combination of both powder X-ray and electron diffraction techniques. Aluminate and water concentrations in the synthetic mixture were found to be the two most critical factors influencing the structural expansion of embedded isoreticular zeolites under the synthetic conditions studied herein.PostprintPostprintPeer reviewe
A Poly(cobaloxime)/Carbon Nanotube Electrode: Freestanding Buckypaper with Polymer-Enhanced H2-Evolution Performance

A freestanding H$_{2}$-evolution electrode consisting of a copolymer-embedded cobaloxime integrated into a multiwall carbon nanotube matrix by π–π interactions is reported. This electrode is straightforward to assemble and displays high activity towards hydrogen evolution in near-neutral pH solution under inert and aerobic conditions, with a cobalt-based turnover number (TONCo) of up to 420. An analogous electrode with a monomeric cobaloxime showed less activity with a TONCo of only 80. These results suggest that, in addition to the high surface area of the porous network of the buckypaper, the polymeric scaffold provides a stabilizing environment to the catalyst, leading to further enhancement in catalytic performance. We have therefore established that the use of a multifunctional copolymeric architecture is a viable strategy to enhance the performance of molecular electrocatalysts.We acknowledge support by the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development), the OMV Group, the EPSRC, the BBSRC (Grant BB/K010220/1) and the Woolf Fisher Trust in New Zealand and the Cambridge Trusts. We also thank the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, UK.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/anie.20151137