bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Detection of Multicarboxylate Anions based on “Turn on” Electron Transfer by Self‐Assembled Molecular Rectangles
Authors: Mishra Anurag , Lee Sunmi , Kim Hyunuk , Cook Timothy R. , Stang Peter J. , Chi Ki‐Whan 
Published: August 2012

AbstractTwo new large molecular rectangles (4 and 5) were obtained by the reaction of two different dinuclear arene ruthenium complexes [Ru2(arene)2(OO)2Cl2] (arene=p‐cymene; OO=2,5‐dihydroxy‐1,4‐benzoquinonato (2), 6,11‐dihydroxy‐5,12‐naphthacene dionato (3)) with the unsymmetrical amide (N‐[4‐(pyridin‐4‐ylethynyl)phenyl]isonicotinamide) donor ligand 1 in methanol in the presence of AgO3SCF3, forming tetranuclear cations of the general formula [Ru4(arene)4()2(O O)2]4+. Both rectangles were isolated in good yields as triflate salts and were characterized by multinuclear NMR, ESI‐MS, UV/Vis, and photoluminescence spectroscopy. The crystal structure of 5 was determined by X‐ray diffraction. Luminescent rectangle 5 was used for anion sensing with an amide ligand as a hydrogen‐bond donor and an arene–ruthenium acceptor as a signaling unit. Rectangle 5 strongly bound multicarboxylate anions, such as oxalate, tartrate, and citrate, in UV/Vis titration experiments in 1:1 ratios, in contrast to monoanions, such as F−, Cl−, NO3−, PF6−, CH3COO−, and C6H5COO−. The fluorescence titration experiment showed a large fluorescence enhancement of 5 upon binding to multicarboxylate anions, which could be attributed to blocking of the photoinduced electron transfer process from the arene–ruthenium moiety to the amidic donor in 5; this was likely to be a result of hydrogen bonding between the ligand and the anion. On the other hand, rectangle 5 was not selective towards any other anions. To the naked eye, multicarboxylate anions in a solution of 5 in methanol appear greenish upon irradiation with UV light.
Size and Shape Control of Metal Nanoparticles for Reaction Selectivity in Catalysis
Authors: An Kwangjin , Somorjai Gabor A. 
Published: August 2012

AbstractA nanoparticle with well‐defined surfaces, prepared through colloidal chemistry, enables it to be studied as a model heterogeneous catalyst. The colloidal synthetic approach provides versatile tools to control the size and shape of nanoparticles. Traditional nucleation and growth mechanisms have been utilized to understand how nanoparticles can be uniformly synthesized and unprecedented shapes can be controlled. Now, the size of metal particles can be controlled to cluster regimes by using dendrimers. By using seeds and foreign atoms, specific synthetic environments such as seeded growth and crystal overgrowth can be induced to generate various shaped mono‐ or bi‐metallic, core/shell, or branched nanostructures. For green chemistry, catalysis in 21st century is aiming for 100 % selectivity to produce only one desired product at high turnover rates. Recent studies on nanoparticle catalysts clearly demonstrate size and shape dependent selectivity in many catalytic reactions. By combining in situ surface characterization techniques, real‐time monitoring of nanoparticles can be performed under reaction environments, thus identifying several molecular factors affecting catalytic activity and selectivity.
The Role of Oxygen‐ and Nitrogen‐containing Surface Groups on the Sintering of Iron Nanoparticles on Carbon Nanotubes in Different Atmospheres
Authors: Sánchez Miguel D. , Chen Peirong , Reinecke Thomas , Muhler Martin , Xia Wei 
Published: August 2012

AbstractThe sintering of iron nanoparticles on carbon nanotubes (CNTs) under different atmospheres was investigated. CNTs were first treated with HNO3 vapor at 200 °C to obtain O‐functionalized CNTs (OCNTs). The OCNTs were treated in ammonia at 400 °C to obtain N‐doped CNTs (NCNTs). Highly dispersed FeOx nanoparticles were subsequently deposited by chemical vapor deposition from ferrocene under oxidizing conditions. The obtained FeOx/OCNT and FeOx/NCNT samples were allowed to sinter at 500 °C under flowing helium, hydrogen, or ammonia. The samples were studied by X‐ray diffraction, transmission electron microscopy, and X‐ray photoelectron spectroscopy. A significant increase in particle size and a decrease in Fe surface atomic concentration were observed in all the sintered samples. The sintering on OCNTs was more severe than on NCNTs, which can be attributed to stronger metal‐substrate interactions and a higher amount of surface defects on NCNTs. The applied gas atmosphere had a substantial influence on the sintering behavior of the nanoparticles: treatment in helium led to the growth of particles and a significant widening of particle size distributions, whereas treatment in hydrogen or ammonia resulted in the growth of particles, but not in the widening of particle size distributions.
Support‐dependent Performance of Size‐selected Subnanometer Cobalt Cluster‐based Catalysts in the Dehydrogenation of Cyclohexene
Authors: Lee Sungsik , Di Vece Marcel , Lee Byeongdu , Seifert Sönke , Winans Randall E. , Vajda Stefan 
Published: August 2012

AbstractThe evolution of the chemical state and change in the morphology of subnanometer cobalt clusters during the dehydrogenation of cyclohexene was investigated in terms of metal‐support interactions. The model catalyst systems were prepared by deposition of size selected subnanometer Co27±4 clusters on various amorphous metal oxide supports (Al2O3, ZnO, and MgO), as well as on a carbon‐based support (UNCD=ultrananocrystaline diamond). The reactivity, oxidation state, and sintering resistance of the clusters were monitored by temperature programmed reaction (TPRx), in situ grazing incidence X‐ray absorption spectroscopy (GIXAS), and grazing incidence small angle X‐ray scattering (GISAXS), respectively. The reactivity and selectivity of cobalt clusters show strong dependency on the support used, with clusters supported on UNCD possessing the highest activity at 300 °C. The evolution of the oxidation state of metal cluster during the reaction reveals that metal‐support interaction plays a key role in performance of the subnanometer catalyst. A reversible assembly of clusters into a nanostructure which evolves with reaction temperature was observed on the MgO support.
Synthesis of Aldehydes by Layer‐by‐Layer Immobilized Laccases in the Presence of Redox Mediators
Authors: Guazzaroni Melissa , Bozzini Tiziana , Saladino Raffaele 
Published: August 2012

AbstractLaccase from Trametes versicolor was immobilized on Eupergit®C250L and alumina particles. The immobilized enzyme was protected by coating with oppositely charged polyelectrolytes by means of the Layer‐by‐Layer (LbL) technique. Enzymatic assay showed that immobilized laccase was more stable than free enzyme at different pH and temperatures without loss of catalytic efficiency. Immobilized laccase based catalysts were efficiently used for the selective oxidation of alcohols to aldehydes in the presence of redox mediators such as ABTS (2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulphonic acid), HBT (1‐hydroxybenzotriazole), VLA (violuric acid) and TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy free radical)
Total Synthesis of Indole‐Derived Allocolchicine Analogues Exhibiting Strong Apoptosis‐Inducing Activity
Authors: Sitnikov Nikolay , Velder Janna , Abodo Liliane , Cuvelier Nicole , Neudörfl Jörg , Prokop Aram , Krause Günter , Fedorov Aleksey Y. , Schmalz Hans‐Günther 
Published: August 2012

AbstractA series of novel pyrrolo‐allocolchicine derivatives (containing a 1‐methyl‐1H‐indol‐5‐yl moiety replacing ring C) was synthesized. The tetracyclic ring system was constructed by Suzuki–Miyaura cross‐coupling of a 1‐methylindole‐5‐boronate with an ortho‐iodo‐dihydrocinnamic acid derivative and subsequent intramolecular Friedel–Crafts acylation. After reduction of the resulting ketone, the nitrogen functionality was introduced in a Mitsunobu‐type reaction by using zinc azide followed by LiAlH4 reduction. Structural assignments were supported by X‐ray crystallography. The compounds synthesized were then tested against BJAB tumor cells and found to exhibit pronounced cytotoxic activity (proliferation inhibition and apoptosis induction). The ketone 24 b was even active at sub‐nanomolar concentration. In addition, the antitumor potential of the compounds was confirmed by using B lymphoid cell lines.
Highly Dispersed TiO6 Units in a Layered Double Hydroxide for Water Splitting
Authors: Zhao Yufei , Chen Pengyun , Zhang Bingsen , Su Dang Sheng , Zhang Shitong , Tian Lei , Lu Jun , Li Zhuoxin , Cao Xingzhong , Wang Baoyi , Wei Min , Evans David G. , Duan Xue 
Published: August 2012

AbstractA family of photocatalysts for water splitting into hydrogen was prepared by distributing TiO6 units in an MTi‐layered double hydroxide matrix (M=Ni, Zn, Mg) that displays largely enhanced photocatalytic activity with an H2‐production rate of 31.4 μmol h−1 as well as excellent recyclable performance. High‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) mapping and XPS measurement reveal that a high dispersion of TiO6 octahedra in the layered doubled hydroxide (LDH) matrix was obtained by the formation of an M2+‐O‐Ti network, rather different from the aggregation state of TiO6 in the inorganic layered material K2Ti4O9. Both transient absorption and photoluminescence spectra demonstrate that the electron–hole recombination process was significantly depressed in the Ti‐containing LDH materials relative to bulk Ti oxide, which is attributed to the abundant surface defects that serve as trapping sites for photogenerated electrons verified by positron annihilation and extended X‐ray absorption fine structure (EXAFS) techniques. In addition, a theoretical study on the basis of DFT calculations demonstrates that the electronic structure of the TiO6 units was modified by the adjacent MO6 octahedron by means of covalent interactions, with a much decreased bandgap of 2.1 eV, which accounts for its superior water‐splitting behavior. Therefore, the dispersion strategy for TiO6 units within a 2D inorganic matrix can be extended to fabricate other oxide or hydroxide catalysts with greatly enhanced performance in photocatalysis and energy conversion.
Development of Domino Processes by Using 7‐Silylcycloheptatrienes and Its Analogues
Authors: Beniazza Redouane , Desvergnes Valérie , Girard Emeline , Kauffmann Brice , Berlande Muriel , Landais Yannick 
Published: August 2012

Abstract7‐Silyl‐ and 7‐silylmethylcycloheptatrienes were shown to react with acylnitroso reagents at room temperature, through their norcaradiene forms, to generate the corresponding cycloadducts 5 a–b and 6 a–b as single diastereomers. The course of the reaction was dramatically modified by changing the reaction conditions. Using a polar medium, functionalized cyclohexa‐1,3‐dienes 7 a–b and bicyclic compounds 13 a–b were instead generated, incorporating one or two amino groups. Similar behavior was observed by using other dienophiles, including triazolinedione, but also activated aldehydes and ketones. A tentative mechanism has been proposed to rationalize the formation of both classes of products that relies on a domino process involving four consecutive elementary steps, in this order: 1) electrocyclic process, 2) hetero‐Diels–Alder reaction, 3) cyclopropane ring opening, and 4) hetero‐Diels–Alder reaction. Trapping of the cationic intermediate and isolation of the primary cycloadduct provide support for this hypothesis. An enantioselective version of the cascade using cycloheptatriene 4 b and aldehydes and ketones, under copper(II) catalysis was also carried out, leading to cyclohexa‐1,3‐dienes 21, 28, and 30 with enantioselectivities up to 93 % ee. Finally, elaboration of the intermediates above has been carried out, opening a straightforward access to sugar mimics 42–43 and complex polycyclic systems 36 and 39.
Increasing the Biomass Flexibility for Power Plants
Authors: Vodegel Stefan , Gehrmann Hans‐Joachim , Bernhardt Daniel , Lyczkowska Angelika 
Published: August 2012

AbstractBiomasseheizkraftwerke werden in Europa vorzugsweise mit Holz betrieben, das aber weltweit nur begrenzt verfügbar ist. Schon jetzt führt eine Verknappung zu einer Verteuerung und damit zu wirtschaftlichen Herausforderungen bei den Betreibern. Daher wird nach alternativen biogenen Einsatzstoffen gesucht. Der möglicherweise kostengünstigeren Beschaffung gegenüber Holz stehen jedoch deren Verbrennungseigenschaften gegenüber, die zu Verschlackung, Korrosion und zusätzlichen Emissionswerten führen können. Über eine prozessorientierte Bewertung von neuen biogenen Brennstoffen in unterschiedlichen thermischen Prozessen werden Chancen und Risiken aufgezeigt, wie sie verstärkt im Markt eingeführt werden können. Dabei spielen nicht nur verfahrenstechnische Gesichtspunkte eine Rolle, sondern auch die Frage, inwieweit sich Nährstoffe zurückgewinnen lassen, um einen Beitrag zur Ressourceneffizienz zu leisten.
Separation of Tin in Recycling of Lead Batteries
Authors: Stelter Michael , Morgenstern Gunter , Beimel Bruno , Zeidler Oliver 
Published: August 2012

AbstractDer gegenwärtig anfallende Akkumulatorenschrott besitzt höhere Zinngehalte als die Bleilegierungen moderner Akkumulatoren. Dadurch fallen bei der Aufarbeitung des Akkuschrotts blei/zinnhaltige Raffinationsprodukte an, die nicht in den Wertstoffkreislauf zurückgeführt werden können. Es wird eine Möglichkeit zur Trennung dieser Produkte beschrieben. Damit hat der Recycler die Möglichkeit, die Wertstoffe Zinn und Blei der Wirtschaft wieder getrennt zur Verfügung zu stellen.
Gram‐Scale Solution‐Phase Synthesis of Selective Sodium Bicarbonate Co‐transport Inhibitor S0859: in vitro Efficacy Studies in Breast Cancer Cells
Authors: Larsen Ann M. , Krogsgaard‐Larsen Niels , Lauritzen Gitte , Olesen Christina W. , Honoré Hansen Steen , Boedtkjer Ebbe , Pedersen Stine F. , Bunch Lennart 
Published: August 2012

AbstractNa+‐coupled HCO3− transporters (NBCs) mediate the transport of bicarbonate ions across cell membranes and are thus ubiquitous regulators of intracellular pH. NBC dysregulation is associated with a range of diseases; for instance, NBCn1 is strongly up‐regulated in a model of ErbB2‐dependent breast cancer, a malignant and widespread cancer with no targeted treatment options, and single‐nucleotide polymorphisms in NBCn1 genetically link to breast cancer development and hypertension. The N‐cyanosulfonamide S0859 has been shown to selectively inhibit NBCs, and its availability on the gram scale is therefore of significant interest to the scientific community. Herein we describe a short and efficient synthesis of S0859 with an overall yield of 45 % from commercially available starting materials. The inhibitory effect of S0859 on recovery of intracellular pH after an acid load was verified in human and murine cancer cell lines in Ringer solutions. However, S0859 binds very strongly to components in plasma, and accordingly, measurements on isolated murine tissues showed no effect of S0859 at concentrations up to 50 μM.
Obesity at diagnosis is associated with inferior outcomes in hormone receptor‐positive operable breast cancer
Authors: Sparano Joseph A. , Wang Molin , Zhao Fengmin , Stearns Vered , Martino Silvana , Ligibel Jennifer A. , Perez Edith A. , Saphner Tom , Wolff Antonio C. , Sledge George W. , Wood William C. , Fetting John , Davidson Nancy E. 
Published: August 2012

AbstractBACKGROUND:Obesity has been associated with inferior outcomes in operable breast cancer, but the relation between body mass index (BMI) and outcomes by breast cancer subtype has not been previously evaluated.METHODS:The authors evaluated the relation between BMI and outcomes in 3 adjuvant trials coordinated by the Eastern Cooperative Oncology Group that included chemotherapy regimens with doxorubicin and cyclophosphamide, including E1199, E5188, and E3189. Results are expressed as hazard ratios (HRs) from Cox proportional hazards models (HR >1 indicates a worse outcome). All P values are 2‐sided.RESULTS:When evaluated as a continuous variable in trial E1199, increasing BMI within the obese (BMI, ≥30 kg/m2) and overweight (BMI, 25‐29.9 kg/m2) ranges was associated with inferior outcomes in hormone receptor‐positive, human epidermal growth receptor 2 (HER‐2)/neu‐negative disease for disease‐free survival (DFS; P = .0006) and overall survival (OS; P = .0007), but not in HER‐2/neu–overexpressing or triple‐negative disease. When evaluated as a categorical variable, obesity was associated with inferior DFS (HR, 1.24; 95% confidence interval [CI], 1.06‐1.46; P = .0008) and OS (HR, 1.37; 95% CI, 1.13‐1.67; P = .002) in hormone receptor‐positive disease, but not other subtypes. In a model including obesity, disease subtype, and their interaction, the interaction term was significant for OS (P = .02) and showed a strong trend for DFS (P = .07). Similar results were found in 2 other trials (E5188, E3189).CONCLUSIONS:In a clinical trial population that excluded patients with significant comorbidities, obesity was associated with inferior outcomes specifically in patients with hormone receptor‐positive operable breast cancer treated with standard chemohormonal therapy. Cancer 2012. © 2012 American Cancer Society.
Influence of bypass angles on extracardiac Fontan connections: a numerical study
Authors: Ding Jinli , Liu Youjun , Wang Feng 
Published: August 2012

SUMMARYThe extracardiac Fontan connection (EFC) is an effective treatment for congenital single ventricle heart defects. Numerous studies have sought to optimize the EFC design. However, the optimal design of EFC remains uncertain. This study aims to examine the influence of bypass angles between the inferior vena cava (IVC) and right pulmonary artery (RPA), and the angles between the IVC and superior vena cava (SVC), on hemodynamics. Furthermore, this study demonstrates a methodology for cardiovascular surgical planning. First, a three‐dimensional anatomical geometry was reconstructed from the medical images of a patient with single ventricle heart defects. Second, based on haptic deformations, six computational models were virtually generated. Third, numerical simulations were conducted using computational fluid dynamics through the finite volume method. Finally, hemodynamic parameters were obtained and evaluated. The hemodynamic parameters, including the flow patterns, streamlines, and swirling flow, were obtained. Meanwhile, the energy loss and flow distributions of vena cava blood were calculated. First, the hepatic artery blood distribution to two lungs and the flow ratio of the left pulmonary artery to RPA are sensitive to the angle between the IVC and RPA and not to that between the IVC and SVC. Second, energy dissipation is mainly sensitive to the angle between the IVC and SVC and not to that between the IVC and RPA. Third, an appropriate increase in the angle between the IVC and RPA or that between the IVC and SVC may lead to optimal options. This study is useful for surgeons in evaluating optimal Fontan options. Copyright © 2012 John Wiley & Sons, Ltd.
Hyperfine Coupling Constants on Inner‐Sphere Water Molecules of GdIII‐Based MRI Contrast Agents
Authors: Esteban‐Gómez David , de Blas Andrés , Rodríguez‐Blas Teresa , Helm Lothar , Platas‐Iglesias Carlos 
Published: August 2012

AbstractHerein we present a theoretical investigation of the hyperfine coupling constants (HFCCs) on the inner‐sphere water molecules of [Gd(H2O)8]3+ and different GdIII‐based magnetic resonance imaging contrast agents such as [Gd(DOTA)(H2O)]−, [Gd(DTPA)(H2O)]2−, [Gd(DTPA‐BMA)(H2O)] and [Gd(HP‐DO3A)(H2O)]. DFT calculations performed on the [Gd(H2O)8]3+ model system show that both hybrid‐GGA functionals (BH&HLYP, B3PW91 and PBE1PBE) and the hybrid meta‐GGA functional TPSSh provide 17O HFCCs in close agreement with the experimental data. The use of all‐electron relativistic approaches based on the DKH2 approximation and the use of relativistic effective core potentials (RECP) provide results of essentially the same quality. The accurate calculation of HFCCs on the [Gd(DOTA)(H2O)]−, [Gd(DTPA)(H2O)]2−, [Gd(DTPA‐BMA)(H2O)] and [Gd(HP‐DO3A)(H2O)] complexes requires an adequate description of solvent effects. This was achieved by using a mixed cluster/continuum approach that includes explicitly two second‐sphere water molecules. The calculated isotropic 17O HFCCs (Aiso) fall within the range 0.40–0.56 MHz, and show deviations from the corresponding experimental values typically lower than 0.05 MHz. The Aiso values are significantly affected by the distance between the oxygen atom of the coordinated water molecule and the GdIII ion, as well as by the orientation of the water molecule plane with respect to the Gd‐O vector. 1H HFCCs of coordinated water molecules and 17O HFCCs of second‐sphere water molecules take values close to zero.
Novel Multifunctional Graphene Sheets with Encased Au/Ag Nanoparticles for Advanced Electrochemical Analysis of Organic Compounds
Authors: Pruneanu Stela , Biris Alexandru R. , Pogacean Florina , Lazar Diana Mihaela , Ardelean Stefania , Watanabe Fumyia , Dervishi Enkeleda , Biris Alexandru S. 
Published: August 2012

AbstractThis work is the first presentation of the synthesis of few‐layer graphene decorated with gold and silver nanoparticles (Gr–Au–Ag) by chemical vapor deposition over a catalytic system formed of bimetallic Au–Ag nanoclusters supported on MgO and with methane used as the source of carbon. The sheetlike morphology of the graphene nanostructures, with mean sizes in the range of hundreds of nanometers, was observed by high‐resolution electron microscopy. The distinctive feature found in all the samples was the regular rectangular or square shapes. This multi‐component organic–inorganic nanomaterial was used to modify a platinum substrate and subsequently employed for the detection of carbamazepine, an anti‐convulsion drug. UV/Vis spectroscopy revealed that a strong hypochromism occurred over time, after mixing solutions of graphene–Au–Ag with carbamazepine. This can be attributed to π–π stacking between the aromatic groups of the two compounds. Linear sweep voltammetry (LCV) provided evidence that the modified platinum substrate presented a significant electrocatalytic reaction toward the oxidation of carbamazepine. The intensity of the current was found to increase by up to 2.5 times, and the oxidation potential shifted from +1.5 to +1.35 V(Ag/AgCl) in comparison with the unmodified electrode. Electrochemical impedance spectroscopy (EIS) was further used to thoroughly assess the activity of the platinum electrode that was modified by the deposition of the Gr‐Au‐Ag composites in the presence of various concentrations of carbamazepine. The experimental EIS records were used for the generation of an equivalent electrical circuit, based on the charge‐transfer resistance (Rct), Warburg impedance (ZD), solution resistance (Rs), and a constant phase element (CPE) that characterizes the non‐ideal interface capacitive responses.