bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐Regenerative Property of Nanocrystalline Ce0.89M0.11O2−y (M=Pd, Rh) Mixed Oxides
Authors: Kurnatowska Michalina , Schuster Manfred E. , Mista Wlodzimierz , Kepinski Leszek 
Published: September 2014

AbstractSelf‐regenerative properties of nanocrystalline Ce0.89M0.11O2−y (M=noble metal, e.g., Pd and Rh) mixed oxides were investigated by applying the reduction–oxidation treatment. These oxides were synthesised as chemically and structurally homogeneous powders (4–5 nm) with a large surface area (≈100 m2 g−1) by using the water‐in‐oil microemulsion method. The analysis of the reduced oxides revealed the presence of the crystalline M particles (size: 2 nm for Pd and 1 nm for Rh) that demonstrate a preferred orientation on the substrate—(1 1 1)M||(1 1 1)CeO2. The size and arrangement of the metal crystallites were the same after each reduction cycle. After oxidation treatment, the M particles disappeared but no distinct particles of an oxide phase (e.g., PdO or Rh2O3) could be detected. However, a thin amorphous layer was visible on the surface of Ce0.89Pd0.11O2−y crystallites. Temperature‐programmed reduction of hydrogen and temperature‐programmed oxidation confirmed the complete reversibility of the redox properties of Ce0.89Rh0.11O2−y after the reduction–oxidation treatment but only partial reversibility for Ce0.89Pd0.11O2−y .
Mild and Selective Hydrogenation of Nitro Compounds using Palladium Nanoparticles Supported on Amino‐Functionalized Mesocellular Foam
Authors: Verho Oscar , Gustafson Karl P. J. , Nagendiran Anuja , Tai Cheuk‐Wai , Bäckvall Jan‐E. 
Published: September 2014

AbstractWe present the utilization of a heterogeneous catalyst comprised of Pd nanoparticles supported on aminopropyl‐functionalized siliceous mesocellular foam (Pd0–AmP–MCF) for the selective hydrogenation of aromatic, aliphatic, and heterocyclic nitro compounds to the corresponding amines. In general, the catalytic protocol exclusively affords the desired amine products in excellent yields within short reaction times with the reactions performed at room temperature under ambient pressure of H2. Moreover, the reported Pd nanocatalyst displayed excellent structural integrity for this transformation as it could be recycled multiple times without any observable loss of activity or leaching of metal. In addition, the Pd nanocatalyst could be easily integrated into a continuous‐flow device and used for the hydrogenation of 4‐nitroanisole on a 2.5 g scale, where the product p‐anisidine was obtained in 95 % yield within 2 h with a Pd content of less than 1 ppm.
Role of Nanointerfaces in Cu‐ and Cu+Au‐Based Near‐Ambient‐Temperature CO Oxidation Catalysts
Authors: Gnanakumar Edwin S. , Naik Jarpla Madhusudhan , Manikandan Marimuthu , Raja Thirumalaiswamy , Gopinath Chinnakonda S. 
Published: September 2014

AbstractDisordered mesoporous Cu‐doped ceria‐zirconia (Cu0.1Ce0.85Zr0.05O2), and gold deposited (Au/Cu0.1Ce0.85Zr0.05O2) catalysts were synthesized and evaluated for CO oxidation. Onset of CO oxidation activity, and 50 % (100 %) CO2 formation occurs at room temperature (RT), and 77 (120)°C, respectively, with Cu0.1Ce0.85Zr0.05O2. A small amount of gold on Cu0.1Ce0.85Zr0.05O2 induces the sustainable oxidation catalysis around RT. Onset of copper reduction temperature decreases from 110 °C on Cu0.1Ce0.85Zr0.05O2 to 48 °C with Au/Cu0.1Ce0.85Zr0.05O2, highlighting the direct interaction between Cu and Au through a Cu–Au interface. Au particles with a (0 0 1) facet deposit on an oxygen‐deficient site of (1 1 1) facet of CeO2‐ZrO2. Any decrease in surface Cu‐content with increasing Au‐content further supports the Au‐Cu‐Ce/Zr interface interactions. Nanointerfaces of Au clusters on Cu next to oxygen‐deficient sites of CeO2‐ZrO2 facilitate all the elementary steps of the CO+O2 reaction to occur in close proximity at ambient conditions.
Zn Electrochemistry in 1‐Ethyl‐3‐Methylimidazolium and N‐Butyl‐N‐Methylpyrrolidinium Dicyanamides: Promising New Rechargeable Zn Battery Electrolytes
Authors: Simons Tristan J. , MacFarlane Douglas R. , Forsyth Maria , Howlett Patrick C. 
Published: September 2014

AbstractWe have studied both 1‐ethyl‐3‐methylimidazolium (C2mim) and N‐butyl‐N‐methylpyrrolidinium (C4mpyr) dicyanamide (dca) ionic liquids (ILs) containing 3 wt % H2O and 9 mol % Zn(dca)2 salt for their ability to support Zn0/2+ electrochemistry in the context of a rechargeable Zn battery. Despite the similarities of the two IL electrolyte systems [identical H2O and Zn(dca)2 contents], the system based on [C2mim] supported much higher current densities for Zn electrochemistry at greatly reduced overpotentials [−0.23 V vs. Zn pseudo‐reference, 32 mA cm−2 (red) and 61 mA cm−2 (ox)] compared to the [C4mpyr]‐based electrolyte [−0.84 V vs. Zn pseudo‐reference, 8 mA cm−2 (red) and 15 mA cm−2 (ox)]. The overpotential for Zn deposition is reduced by 0.13 V on Zn metal surfaces compared to glassy carbon (GC), regardless of the electrolyte used. The morphologies of the Zn deposits on both GC and Zn surfaces were also studied. The Zn surfaces promote a deposition that displays a smooth morphology, resulting from an instantaneous nucleation mechanism demonstrated by chronoamperometric experiments. Finally, both [C2mim] and [C4mpyr] electrolytes were tested in symmetrical Zn|Zn cells, where it was determined that the [C2mim] system could sustain over 90 cycles at 0.1 mA cm−2, whereas the [C4mpyr] based system could only achieve 15 cycles at the more modest current density of 0.05 mA cm−2.
Microbial Electroreduction: Screening for New Cathodic Biocatalysts
Authors: de Campos Rodrigues Tatiana , Rosenbaum Miriam A. 
Published: September 2014

AbstractCathodic microbial electrocatalysis, where microorganisms consume electrons from a cathode to perform biochemical reductions, is currently of high interest. For an effective electrochemical screening of potential new cathode biocatalysts, we developed a time‐saving medium‐throughput potentiostatic BES system to evaluate microbial ability to accept reducing equivalents from an electrode in pure cultures. Of nine tested physiologically and phylogenetically different strains, five promising cathode‐active strains were identified: Acidithiobacillus ferrooxidans (jmax=−50 μA cm−2), Desulfosporosinus orientis (jmax=−4 μA cm−2), Thiobacillus denitrificans and Sulfurimonas denitrificans (jmax=−2 μA cm−2 for both), and Desulfovibrio piger (jmax=−1.5 μA cm−2). From this screening, hypotheses were formulated on possible electron consumption and utilization processes. This work serves as a foundation for deeper investigation and characterization of the identified cathode biocatalysts.
Dissymmetrical U‐Shaped π‐Stacked Supramolecular Assemblies by Using a Dinuclear CuI Clip with Organophosphorus Ligands and Monotopic Fully π‐Conjugated Ligands
Authors: El Sayed Moussa Mehdi , Guillois Kevin , Shen Wenting , Réau Régis , Crassous Jeanne , Lescop Christophe 
Published: September 2014

AbstractReactions between the U‐shaped binuclear CuI complex A that bears short metal–metal distances and the cyano‐capped monotopic π‐conjugated ligands 1–5 that carry gradually bulkier polyaromatic terminal fragments lead to the formation of π‐stacked supramolecular assemblies 6–10, respectively, in yields of 50–80 %. These derivatives have been characterized by multinuclear NMR spectroscopic analysis and X‐ray diffraction studies. Their solid‐state structures show the selective formation of U‐shaped supramolecular assemblies in which two monotopic π‐conjugated systems present large (6, 7, and 9) or medium (8 and 10) intramolecular π overlap, thus revealing π–π interactions. These assemblies self‐organize into head‐to‐tail π‐stacked dimers that in turn self‐assemble to afford infinite columnar π stacks. The nature, extent, and complexity of the intermolecular contacts within the head‐to‐tail π‐stacked dimer depend on the nature of the terminal polyaromatic fragment carried by the cyano‐capped monotopic ligand, but it does not alter the result of the self‐assembling process. These results demonstrate that the dinuclear molecular clip A that bears short metal–metal distances allows selective supramolecular assembly processes driven by the formation of intra‐ and intermolecular short π–π interactions in the resulting self‐assembled structures; thus, demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extended π‐stacked columns based on dissymmetrical and functional π‐conjugated systems.
Targeted Functionalization of Porous Materials for Separation of Alcohol/Water Mixtures by Modular Assembly
Authors: Ren Cai‐Xia , Ji Min , Yao Qing‐Xia , Cai Li‐Xuan , Tan Bin , Zhang Jie 
Published: September 2014

AbstractThree isoreticular hydrogen‐bonded frameworks with functionalized pore structures were constructed by a modular self‐assembly process in which a series of amino acids with various substituents serve as facile exchange subassemblies to decorate the pore wall. The ordered amino acid side‐chain groups in the pore channels play an important role in determining the adsorption behavior of the framework materials, and ensure exclusive adsorption of methanol/water over ethanol. Gas‐chromatographic separation experiments demonstrated that alcohols can be efficiently separated from ternary water/methanol/ethanol mixtures and revealed a key influence of the adsorbate–host framework interaction on the practical separation performance of mixtures.
A Bis(pyridine N‐oxide) Analogue of DOTA: Relaxometric Properties of the GdIII Complex and Efficient Sensitization of Visible and NIR‐Emitting Lanthanide(III) Cations Including PrIII and HoIII
Authors: Martins André F. , Eliseeva Svetlana V. , Carvalho Henrique F. , Teixeira João M. C. , Paula Carlos T. B. , Hermann Petr , Platas‐Iglesias Carlos , Petoud Stephane , Tóth Éva , Geraldes Carlos F. G. C. 
Published: September 2014

AbstractWe report the synthesis of a cyclen‐based ligand (4,10‐bis[(1‐oxidopyridin‐2‐yl)methyl]‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid=L1) containing two acetate and two 2‐methylpyridine N‐oxide arms anchored on the nitrogen atoms of the cyclen platform, which has been designed for stable complexation of lanthanide(III) ions in aqueous solution. Relaxometric studies suggest that the thermodynamic stability and kinetic inertness of the GdIII complex may be sufficient for biological applications. A detailed structural study of the complexes by 1H NMR spectroscopy and DFT calculations indicates that they adopt an anti‐Δ(λλλλ) conformation in aqueous solution, that is, an anti‐square antiprismatic (anti‐SAP) isomeric form, as demonstrated by analysis of the 1H NMR paramagnetic shifts induced by YbIII. The water‐exchange rate of the GdIII complex is ${k{{298\hfill \atop {\rm ex}\hfill}}}$=6.7×106 s−1, about a quarter of that for the mono‐oxidopyridine analogue, but still about 50 % higher than the ${k{{298\hfill \atop {\rm ex}\hfill}}}$ of GdDOTA (DOTA=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The 2‐methylpyridine N‐oxide chromophores can be used to sensitize a wide range of LnIII ions emitting in both the visible (EuIII and TbIII) and NIR (PrIII, NdIII, HoIII, YbIII) spectral regions. The emission quantum yield determined for the YbIII complex (${Q{{{\rm L}\hfill \atop {\rm Yb}\hfill}}}$=7.3(1)×10−3) is among the highest ever reported for complexes of this metal ion in aqueous solution. The sensitization ability of the ligand, together with the spectroscopic and relaxometric properties of its complexes, constitute a useful step forward on the way to efficient dual probes for optical imaging (OI) and MRI.
Quantitative Description of Structural Effects on the Stability of Gold(I) Carbenes
Authors: Ringger David H. , Kobylianskii Ilia J. , Serra Daniel , Chen Peter 
Published: September 2014

AbstractThe gas‐phase bond‐dissociation energies of a SO2–imidazolylidene leaving group of three gold(I) benzyl imidazolium sulfone complexes are reported (E0=46.6±1.7, 49.6±1.7, and 48.9±2.1 kcal mol−1). Although these energies are similar to each other, they are reproducibly distinguishable. The energy‐resolved collision‐induced dissociation experiments of the three [L]–gold(I) (L=ligand) carbene precursor complexes were performed by using a modified tandem mass spectrometer. The measurements quantitatively describe the structural and electronic effects a p‐methoxy substituent on the benzyl fragment, and trans [NHC] and [P] gold ligands, have towards gold carbene formation. Evidence for the formation of the electrophilic gold carbene in solution was obtained through the stoichiometric and catalytic cyclopropanation of olefins under thermal conditions. The observed cyclopropane yields are dependent on the rate of gold carbene formation, which in turn is influenced by the ligand and substituent. The donation of electron density to the carbene carbon by the p‐methoxy benzyl substituent and [NHC] ligand stabilizes the gold carbene intermediate and lowers the dissociation barrier. Through the careful comparison of gas‐phase and solution chemistry, the results suggest that even gas‐phase leaving‐group bond‐dissociation energy differences of 2–3 kcal mol−1 enormously affect the rate of gold carbene formation in solution, especially when there are competing reactions. The thermal decay of the gold carbene precursor complex was observed to follow first‐order kinetics, whereas cyclopropanation was found to follow pseudo‐first‐order kinetics. Density‐functional‐theory calculations at the M06‐L and BP86‐D3 levels of theory were used to confirm the observed gas‐phase reactivity and model the measured bond‐dissociation energies.
BrettPhos Ligand Supported Palladium‐Catalyzed CO Bond Formation through an Electronic Pathway of Reductive Elimination: Fluoroalkoxylation of Activated Aryl Halides
Authors: Rangarajan T. M. , Singh Rajendra , Brahma Raju , Devi Kavita , Singh Rishi Pal , Singh R. P. , Prasad Ashok K. 
Published: September 2014

AbstractWe report an unprecedented BrettPhos ligand supported Pd‐catalyzed CO bond‐forming reaction of activated aryl halides with primary fluoroalkyl alcohols. We demonstrate that the Phosphine ligand (BrettPhos) possesses the property of altering the mechanistic pathway of reductive elimination from nucleophile to nucleophile. The Pd/BrettPhos catalyst system facilitates the reductive elimination of the oxygen nucleophile through an electronic pathway.
Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives
Authors: Thomas Joice , Jejcic Alenka , Vervaeke Peter , Romagnoli Romeo , Liekens Sandra , Balzarini Jan , Dehaen Wim 
Published: September 2014

AbstractMethyl‐2‐amino‐5‐[2‐(4‐methoxyphenethyl)]thiophene‐3‐carboxylate (8 c) is the prototype of a well‐defined class of tumor‐selective agents. Compound 8 c preferentially inhibited the proliferation of a number of tumor cell lines including many human T‐lymphoma/leukemia cells, but also several prostate, renal, central nervous system and liver tumor cell types. Instead, a broad variety of other tumor cell lines including B‐lymphomas and HeLa cells were not affected. The tumor selectivity (TS; selectivity index or preferential suppression of CEM lymphoma (IC50=0.90 μM) versus HeLa tumor cell carcinoma (IC50=39 μM)) amounted up to ∼43 for 8 c. At higher concentrations, the compound proved cytotoxic rather than cytostatic. The antiproliferative potency and selectivity of 8 c could be preserved by replacing the ethyl linker between the 2‐amino‐3‐carboxymethylthiophene and the substituted aryl by a thioalkyl but not by an oxyalkyl nor an aminoalkyl. Among >50 novel 8 c derivatives, the 5‐(4‐ethyl‐ and 4‐isopropylarylmethylthio)thiophene analogues, methyl‐2‐amino‐5‐((4‐ethylphenylthio)methyl)thiophene‐3‐carboxylate (13 m) and methyl‐2‐amino‐5‐((4‐isopropylphenylthio)methyl)thiophene‐3‐carboxylate (13 n), were more potent (IC50: 0.3–0.4 μM) and selective (TS: 100–144) anti‐T‐lymphoma/leukemia agents than the prototype compound.
Design and Structural Analysis of Aromatic Inhibitors of Type II Dehydroquinase from Mycobacterium tuberculosis
Authors: Howard Nigel I. , Dias Marcio V. B. , Peyrot Fabienne , Chen Liuhong , Schmidt Marco F. , Blundell Tom L. , Abell Chris 
Published: September 2014

Abstract3‐Dehydroquinase, the third enzyme in the shikimate pathway, is a potential target for drugs against tuberculosis. Whilst a number of potent inhibitors of the Mycobacterium tuberculosis enzyme based on a 3‐dehydroquinate core have been identified, they generally show little or no in vivo activity, and were synthetically complex to prepare. This report describes studies to develop tractable and drug‐like aromatic analogues of the most potent inhibitors. A range of carbon–carbon linked biaryl analogues were prepared to investigate the effect of hydrogen bond acceptor and donor patterns on inhibition. These exhibited inhibitory activity in the high‐micromolar range. The addition of flexible linkers in the compounds led to the identification of more potent 3‐nitrobenzylgallate‐ and 5‐aminoisophthalate‐based analogues.
Endoscopic ultrasonography in esophageal cancer leads to improved survival rates: Results from a population‐based study
Authors: Wani Sachin , Das Ananya , Rastogi Amit , Drahos Jennifer , Ricker Winifred , Parsons Ruth , Bansal Ajay , Yen Roy , Hosford Lindsay , Jankowski Meghan , Sharma Prateek , Cook Michael B. 
Published: September 2014

BACKGROUNDThe advantages of endoscopic ultrasound (EUS) and computed tomography (CT)–positron emission tomography (PET) with respect to survival for esophageal cancer patients are unclear. This study aimed to assess the effects of EUS, CT‐PET, and their combination on overall survival with respect to cases not receiving these procedures.METHODSPatients who were ≥66 years old when diagnosed with esophageal cancer were identified in the Surveillance, Epidemiology, and End Results–Medicare linked database. Cases were split into 4 analytic groups: EUS only (n = 318), CT‐PET only (n = 853), EUS+CT‐PET (n = 189), and no EUS or CT‐PET (n = 2439). Survival times were estimated with the Kaplan‐Meier method and were compared with the log‐rank test for each group versus the no EUS or CT‐PET group. Multivariate Cox proportional hazards models were used to compare 1‐, 3‐, and 5‐year survival rates.RESULTSKaplan‐Meier analyses showed that EUS, CT‐PET, and EUS+CT‐PET patients had improved survival for all stages (with the exception of stage 0 disease) in comparison with patients undergoing no EUS or CT‐PET. Receipt of EUS increased the likelihood of receiving endoscopic therapies, esophagectomy, and chemoradiation. Multivariate Cox proportional hazards models showed that receipt of EUS was a significant predictor of improved 1‐ (hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.39‐0.59; P < .0001), 3‐ (HR, 0.57; 95% CI, 0.48‐0.66; P < .0001), and 5‐year survival (HR, 0.59; 95% CI, 0.50‐0.68). Similar results were noted when the results were stratified on the basis of histology and for the CT‐PET and EUS+CT‐PET groups.CONCLUSIONSReceipt of either EUS or CT‐PET alone in esophageal cancer patients was associated with improved 1‐, 3‐, and 5‐year survival. Future studies should identify barriers to the dissemination of these staging modalities. Cancer 2015;121:194–201. © 2014 American Cancer Society.
Significant clinical impact of recurrent BRCA1 and BRCA2 mutations in Mexico
Authors: Villarreal‐Garza Cynthia , Alvarez‐Gómez Rosa María , Pérez‐Plasencia Carlos , Herrera Luis A. , Herzog Josef , Castillo Danielle , Mohar Alejandro , Castro Clementina , Gallardo Lenny N. , Gallardo Dolores , Santibáñez Miguel , Blazer Kathleen R. , Weitzel Jeffrey N. 
Published: September 2014

BACKGROUNDFrequent recurrent mutations in the breast and ovarian cancer susceptibility (BRCA) genes BRCA1 and BRCA2 among Hispanics, including a large rearrangement Mexican founder mutation (BRCA1 exon 9‐12 deletion [ex9‐12del]), suggest that an ancestry‐informed BRCA‐testing strategy could reduce disparities and promote cancer prevention by enabling economic screening for hereditary breast and ovarian cancer in Mexico.METHODSIn a multistage approach, 188 patients with cancer who were unselected for family cancer history (92 with ovarian cancer and 96 with breast cancer) were screened for BRCA mutations using a Hispanic mutation panel (HISPANEL) of 115 recurrent mutations in a multiplex assay (114 were screened on a mass spectroscopy platform, and a polymerase chain reaction assay was used to screen for the BRCA1 ex9‐12del mutation). This was followed by sequencing of all BRCA exons and adjacent intronic regions and a BRCA1 multiplex ligation‐dependent probe amplification assay (MLPA) for HISPANEL‐negative patients. BRCA mutation prevalence was calculated and correlated with histology and tumor receptor status, and HISPANEL sensitivity was estimated.RESULTSBRCA mutations were detected in 26 of 92 patients (28%) with ovarian cancer, in 14 of 96 patients (15%) with breast cancer overall, and in 9 of 33 patients (27%) who had tumors that were negative for estrogen receptor, progesterone receptor, and human epithelial growth factor 2 (triple‐negative breast cancer). Most patients with breast cancer were diagnosed with locally advanced disease. The Mexican founder mutation (BRCA1 ex9‐12del) accounted for 35% of BRCA‐associated ovarian cancers and 29% of BRCA‐associated breast cancers. At 2% of the sequencing and MLPA cost, HISPANEL detected 68% of all BRCA mutations.CONCLUSIONSIn this study, a remarkably high prevalence of BRCA mutations was observed among patients with ovarian cancer and breast cancer who were not selected for family history, and the BRCA1 ex9‐12del mutation explained 33% of the total. The remarkable frequency of BRCA1 ex9‐12del in Mexico City supports a nearby origin of this Mexican founder mutation and may constitute a regional public health problem. The HISPANEL mutation panel presents a translational opportunity for cost‐effective genetic testing to enable breast and ovarian cancer prevention. Cancer 2015;121:372–378. © 2014 American Cancer Society.
A Theoretical Analysis of the Potential Role of π–π Stacking Interactions in the Photoprotolytic Cycle of Firefly Luciferin
Authors: Pinto da Silva Luís , Esteves da Silva Joaquim C. G. 
Published: September 2014

AbstractFirefly oxyluciferin is a photoacid that presents a pH‐sensitive fluorescence, which results from pH‐dependent changes on the conformation of self‐aggregated π–π stacking complexes. Luciferin is a derivative of oxyluciferin with very similar fluorescence and photoacidic properties. This similarity indicates that luciferin is also expected to be able to form π–π stacking complexes, but no pH‐sensitive fluorescence is found for this compound. Here, a theoretical approach is used to rationalize this finding. We have found that luciferin only forms π–π stacking complexes in the ground state at acidic pH. At basic pH and in the excited state, luciferin is present as a dianion. This species is not able to self‐aggregate, owing to repulsive electrostatic interactions. Thus, this emissive species is not subject to π–π stacking interactions; this explains its pH‐insensitive fluorescence.
Substitution‐Controlled Excited State Processes in Heteroleptic Copper(I) Photosensitizers Used in Hydrogen Evolving Systems
Authors: Tschierlei Stefanie , Karnahl Michael , Rockstroh Nils , Junge Henrik , Beller Matthias , Lochbrunner Stefan 
Published: September 2014

AbstractFour different heteroleptic [Cu(N^N)(P^P)]PF6 complexes, which combine classical bidentate diimine ligands and sterically demanding diphosphine ligands, are studied by a combination of ultrafast time‐resolved spectroscopy and quantum chemical calculations. The light‐induced excited state processes, accompanied by a structural change, are discussed with respect to the application of these complexes as a new class of noble‐metal‐free photosensitizers in proton reducing systems. In particular, the influence of different substituents in the ligand backbone on the photophysical properties is highlighted.