bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion‐Pair SN2 Substitution: Activation Strain Analyses of Counter‐Ion and Solvent Effects
Authors: Laloo Jalal Z. A. , Rhyman Lydia , Ramasami Ponnadurai , Bickelhaupt F. Matthias , de Cózar Abel 
Published: February 2016

AbstractThe ion‐pair SN2 reactions of model systems MnFn−1+CH3Cl (M+=Li+, Na+, K+, and MgCl+; n=0, 1) have been quantum chemically explored by using DFT at the OLYP/6‐31++G(d,p) level. The purpose of this study is threefold: 1) to elucidate how the counterion M+ modifies ion‐pair SN2 reactivity relative to the parent reaction F−+CH3Cl; 2) to determine how this influences stereochemical competition between the backside and frontside attacks; and 3) to examine the effect of solvation on these ion‐pair SN2 pathways. Trends in reactivity are analyzed and explained by using the activation strain model (ASM) of chemical reactivity. The ASM has been extended to treat reactivity in solution. These findings contribute to a more rational design of tailor‐made substitution reactions.
Abnormal Cathodic Photocurrent Generated on an n‐Type FeOOH Nanorod‐Array Photoelectrode
Authors: Chen Hongjun , Lyu Miaoqiang , Liu Gang , Wang Lianzhou 
Published: February 2016

AbstractA simple, wet‐chemical method for the synthesis of an FeOOH nanorod‐array photoelectrode on fluorine‐doped tin oxide (FTO) glass is reported. Nanorods of diameter about 35 nm and length about 300 nm have been vertically grown on an FTO substrate. Upon calcination, the FeOOH phase could be easily converted to a hematite structure while maintaining the shape of the nanorod array. An interesting abnormal cathodic photocurrent is generated on the FeOOH nanorod‐array photoelectrode under illumination, which is totally different from that obtained on a calcined hematite photoelectrode under the same experimental conditions. The cathodic photocurrent density generated on the FeOOH photoelectrode can also be tuned by applying an electrochemical anodic or cathodic treatment. Detailed analysis has revealed that higher valence state FeIV species in the FeOOH photoelectrode play an important role in sacrificing the photoexcited electrons for generation of the cathodic photocurrent. Comparison between the FeOOH and hematite photoelectrodes allows for a better understanding of the interplay between crystal structure, surface reactions, and photocurrent. The findings on this new abnormal phenomenon could also provide guidance for the design of new types of semiconducting photoelectrochemical devices.
Nitration of Norcorrolatonickel(II): First Observation of a Diatropic Current in a System Comprising a Norcorrole Ring
Authors: Deng Zhihong , Li Xiaofang , Stępień Marcin , Chmielewski Piotr J. 
Published: February 2016

AbstractA one‐pot reaction of 5,14‐bis(mesityl)‐norcorrolatonickel(II) with isoamyl nitrite under mild reaction conditions resulted in the consecutive formation of 3‐nitro‐, 3,12‐dinitro‐ and 3,16‐dinitro‐, 3,7,12‐trinitro‐, and 3,7,12,16‐tetranitro‐norcorrolatonickel(II) in 50–80 % yield. The substituted macrocycles retained their antiaromatic character. The observed regioselectivity of the substitution was analyzed by comparing the relative energies of the DFT energy‐optimized models of the radical or arenium cationic intermediates that can be formed upon reaction with NO2. The nitrated systems were characterized by high‐resolution mass spectrometry, NMR and UV/Vis spectroscopy, X‐ray diffraction analysis, cyclic voltammetry, and DFT calculations. A significant and systematic cathodic shift of the redox couples was observed to correlate with an increasing number of the NO2 group. A decrease of the LUMO energies in the tri‐ and tetra‐nitrated products stabilizes mono‐ and bis‐reduced complexes of these ligands. The reduction takes place on the macrocycle rather than on the metal ion leading to the consecutive formation of stable paramagnetic monoanion radicals and water‐soluble diamagnetic dianions with an aromatic character, which were revealed by ESR and 1H NMR measurements, respectively. The electronic structures of the reduced forms were analyzed by extensive TD‐DFT calculations.
Biodegradable Peptide–Silica Nanodonuts
Authors: Maggini Laura , Travaglini Leana , Cabrera Ingrid , Castro‐Hartmann Pablo , De Cola Luisa 
Published: February 2016

AbstractWe report hybrid organosilica toroidal particles containing a short peptide sequence as the organic component of the hybrid systems. Once internalised in cancer cells, the presence of the peptide allows for interaction with peptidase enzymes, which attack the nanocarrier effectively triggering its structural breakdown. Moreover, these biodegradable nanovectors are characterised by high cellular uptake and exocytosis, showing great potential as biodegradable drug carriers. To demonstrate this feature, doxorubicin was employed and its delivery in HeLa cells investigated.
Control of Surface Plasmon Resonance of Au/SnO2 by Modification with Ag and Cu for Photoinduced Reactions under Visible‐Light Irradiation over a Wide Range
Authors: Tanaka Atsuhiro , Hashimoto Keiji , Kominami Hiroshi 
Published: February 2016

AbstractGold particles supported on tin(IV) oxide (0.2 wt % Au/SnO2) were modified with copper and silver by the multistep photodeposition method. Absorption around λ=550 nm, attributed to surface plasmon resonance (SPR) of Au, gradually shifted to longer wavelengths on modification with Cu and finally reached λ=620 nm at 0.8 wt % Cu. On the other hand, the absorption shifted to shorter wavelength with increasing amount of Ag and reached λ=450 nm at 0.8 wt % Ag. These Cu‐ and Ag‐modified 0.2 wt % Au/SnO2 materials (Cu‐Au/SnO2 and Ag‐Au/SnO2) and 1.0 wt % Au/SnO2 were used for mineralization of formic acid to carbon dioxide in aqueous suspension under irradiation with visible light from a xenon lamp and three kinds of light‐emitting diodes with different wavelengths. The reaction rates for the mineralization of formic acid over these materials depend on the wavelength of light. Apparent quantum efficiencies of Cu‐Au/SnO2, Au/SnO2, and Ag‐Au/SnO2 reached 5.5 % at 625 nm, 5.8 % at 525 nm, and 5.1 % at 450 nm, respectively. These photocatalysts can also be used for selective oxidation of alcohols to corresponding carbonyl compounds in aqueous solution under visible‐light irradiation. Broad responses to visible light in formic acid mineralization and selective alcohol oxidation were achieved when the three materials were used simultaneously.
Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes
Authors: Papadas Ioannis T. , Fountoulaki Stella , Lykakis Ioannis N. , Armatas Gerasimos S. 
Published: February 2016

AbstractIron(III) oxide is a low‐cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe2O3 with high surface area‐to‐volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4–5 nm γ‐Fe2O3 nanoparticles by a polymer‐assisted aggregating self‐assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open‐pore structure with high surface area (up to 167 m2 g−1) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ‐Fe2O3 to α‐Fe2O3 and to Fe3O4 under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large‐scale synthesis.
Reversible Morphological Evolution of Responsive Giant Vesicles to Nanospheres by the Self‐Assembly of Crystalline‐b‐Coil Polyphosphazene Block Copolymers
Authors: Suárez‐Suárez Silvia , Carriedo Gabino A. , Presa Soto Alejandro 
Published: February 2016

AbstractThe preparation of long‐term‐stable giant unilamellar vesicles (GUVs, diameter ≥1000 nm) and large vesicles (diameter ≥500 nm) by self‐assembly in THF of the crystalline‐b‐coil polyphosphazene block copolymers [N=P(OCH2CF3)2]n‐b‐[N=PMePh]m (4 a: n=30, m=20; 4 b: n=90, m=20; 4 c: n=200, m=85), which combine crystalline [N=P(OCH2CF3)2] and amorphous [N=PMePh] blocks, both of which are flexible, is reported. SEM, TEM, and wide‐angle X‐ray scattering experiments demonstrated that the stability of these GUVs is induced by crystallization of the [N=P(OCH2CF3)2] blocks at the capsule wall of the GUVS, with the [N=PMePh] blocks at the corona. Higher degrees of crystallinity of the capsule wall are found in the bigger vesicles, which suggests that the crystallinity of the [N=P(OCH2CF3)2] block facilitates the formation of large vesicles. The GUVs are responsive to strong acids (HOTf) and, after selective protonation of the [N=PMePh] block, they undergo a morphological evolution to smaller spherical micelles in which the core and corona roles have been inverted. This morphological evolution is totally reversible by neutralization with a base (NEt3), which regenerates the original GUVs. The monitoring of this process by dynamic light scattering allowed a mechanism to to be proposed for this reversible morphological evolution in which the block copolymer 4 a and its protonated form 4 a+ are intermediates. This opens a route to the design of reversibly responsive polymeric systems in organic solvents. This is the first reversibly responsive vesicle system to operate in organic media.
Heteroleptic Tetrapyrrole‐Fused Dimeric and Trimeric Skeletons with Unusual Non‐Frustrated Fluorescence
Authors: Zhang Yuehong , Oh Juwon , Wang Kang , Chen Chao , Cao Wei , Park Kyu Hyung , Kim Dongho , Jiang Jianzhuang 
Published: February 2016

AbstractPhthalocyanine (Pc) and porphyrin (Por) chromophores have been fused through the benzo[α]pyrazine moiety, resulting in unprecedented heteroleptic tetrapyrrole‐fused dimers and trimers. The heteroleptic tetrapyrrole nature has been clearly revealed based on single‐crystal X‐ray diffraction analysis of the zinc dimer. Electrochemical analysis, theoretical calculations, and time‐resolved spectroscopic results disclose that the two/three‐tetrapyrrole‐fused skeletons behave as one totally π‐conjugated system as a result of the strong conjugative interaction between/among the tetrapyrrole chromophores. In particular, the effectively extended π‐electron system through the fused‐bridge induced strong electronic communication between the Pc and Por moieties and large transition dipole moments in the Pc–Por‐fused systems, providing high fluorescence quantum yields (>0.13) and relatively long excited state lifetimes (>1.3 ns) in comparison with their homo‐tetrapyrrole‐fused analogues.
Structural Collapse of the Hydroquinone–Formic Acid Clathrate: A Pressure‐Medium‐Dependent Phase Transition
Authors: Eikeland Espen , Thomsen Maja K. , Madsen Solveig R. , Overgaard Jacob , Spackman Mark A. , Iversen Bo. B. 
Published: February 2016

AbstractThe energy landscape governing a new pressure‐induced phase transition in the hydroquinone–formic acid clathrate is reported in which the host structure collapses, opening up the cavity channels within which the guest molecules migrate and order. The reversible isosymmetric phase transition causes significant changes in the morphology and the birefringence of the crystal. The subtle intermolecular interaction energies in the clathrate are quantified at varying pressures using novel model energies and energy frameworks. These calculations show that the high‐pressure phase forms a more stable host network at the expense of less‐stable host–guest interactions. The phase transition can be kinetically hindered using a nonhydrostatic pressure‐transmitting medium, enabling the comparison of intermolecular energies in two polymorphic structures in the same pressure range. Overall this study illustrates a need for accurate intermolecular energies when analyzing self‐assembly structures and supramolecular aggregates.
Selectivity Effects in Bimetallic Catalysis
Authors: Mankad Neal P. 
Published: February 2016

AbstractAn emerging area of homogeneous catalysis is the use of catalysts featuring two closely associated metal sites. This approach complements the traditional focus on single‐site catalysts and makes available new parameters with which to optimize catalytic behavior. Single‐site catalysts are optimized through changing 1) the identity of the metal, and 2) the steric and electronic properties of the ligands. Bimetallic catalysts introduce new optimization parameters such as 3) catalyst nuclearity (mononuclear vs. binuclear), and 4) bimetallic pairing (relative compatibility of two metal sites). In order to harness these new optimization parameters in developing systems, it is necessary to first understand the origin of bimetallic selectivity effects that already have been documented. This Concept article highlights bimetallic effects on the chemo‐, regio‐, and stereoselectivity of catalytic transformations, using selected case studies from the recent literature as illustrative examples.
The Quadruple Bonding in C2 Reproduces the Properties of the Molecule
Authors: Shaik Sason , Danovich David , Braida Benoit , Hiberty Philippe C. 
Published: February 2016

AbstractEver since Lewis depicted the triple bond for acetylene, triple bonding has been considered as the highest limit of multiple bonding for main elements. Here we show that C2 is bonded by a quadruple bond that can be distinctly characterized by valence‐bond (VB) calculations. We demonstrate that the quadruply‐bonded structure determines the key observables of the molecule, and accounts by itself for about 90 % of the molecule's bond dissociation energy, and for its bond lengths and its force constant. The quadruply‐bonded structure is made of two strong π bonds, one strong σ bond and a weaker fourth σ‐type bond, the bond strength of which is estimated as 17–21 kcal mol−1. Alternative VB structures with double bonds; either two π bonds or one π bond and one σ bond lie at 129.5 and 106.1 kcal mol−1, respectively, above the quadruply‐bonded structure, and they collapse to the latter structure given freedom to improve their double bonding by dative σ bonding. The usefulness of the quadruply‐bonded model is underscored by “predicting” the properties of the 3
state. C2’s very high reactivity is rooted in its fourth weak bond. Thus, carbon and first‐row main elements are open to quadruple bonding!
Mit der Eberesche vom Heimatlied zur Frühstücksmagarine
Authors: Selg Christoph , Geißler David , Sicker Dieter , Siehl Hans‐Ullrich , Zeller Klaus‐Peter , Berger Stefan 
Published: February 2016

AbstractDie Eberesche gehört zu den anpassungsfähigen Bäumen der Pioniervegetation. Vogelbeeren sind die Früchte der Eberesche. Sie sind essbar, aber es ist nötig zu wissen, wie sie zuzubereiten sind, damit ihr Verzehr ein Genuss wird. Auch volksmedizinische Anwendungen sind bekannt. Der Vogelbeerbaum wird so geschätzt, dass es sogar ein Volkslied über ihn gibt. Typisch sind die Inhaltsstoffe Parasorbosid (1), ein Glucosid, und Parasorbinsäure (2), ein Lacton und Sorbinsäure (3), eine isomere ungesättigte Carbonsäure. Diese ist ein Konservierungsstoff, welcher sich chemisch aus 2 herstellen lässt. In über 100 Jahren ermittelten z.T. berühmte Chemiker diese Strukturen. Wir beschreiben den Zugang zu 1, 2 und 3 auf Vogelbeerenbasis. Alle analytischen Spektren werden vollständig entweder im Hauptteil oder in der supporting information wiedergegeben und interpretiert.
The impact of sense of duty on brand community outcomes
Authors: Goellner Katharina , Mark Tanya , Alvarado Jennifer 
Published: February 2016

AbstractResearch suggests that three markers are essential for a successful brand community: a sense of belonging, rituals and tradition, and a sense of duty toward the community. The first two of these markers have been empirically validated; however, the third marker, sense of duty, has yet to be empirically investigated. From a marketing perspective, this is important because there is a need to understand the marketing levers that influence favourable behavioural outcomes. We find that sense of duty is a decisive mediator of brand community behaviours and social identity. In addition, we find that sense of duty is a multidimensional construct consisting of three distinct components: new member integration, mentorship, and member retention. Copyright © 2016 ASAC. Published by John Wiley & Sons, Ltd.
Lipoprotein(a) and Increased Cardiovascular Risk in Women
Authors: Costello Briana T. , Silverman Eric R. , Doukky Rami , Braun Lynne T. , Aggarwal Neelum T. , Deng Youping , Li Yan , Lundberg Gina , Williams Kim A. , Volgman Annabelle S. 
Published: February 2016

AbstractBackgroundApproximately 20% of the population has elevated circulating levels of lipoprotein(a) (Lp[a]), one of the most robust predictors of cardiovascular disease risk. This is particularly true for women.HypothesisMany female patients with “normal” traditional risk factors or low atherosclerotic cardiovascular disease (ASCVD) risk scores may harbor high risk related to elevated levels of Lp(a).MethodsA retrospective, cross‐sectional study of consecutive female patients presenting to Heart Centers for Women was performed. Discordance between low‐density lipoprotein cholesterol (LDL‐C) and Lp(a) was determined. The ASCVD risk and Reynolds Risk Score models A (RRS‐A) and B (RRS‐B) were calculated, and level of agreement in patients meeting treatment threshold (≥7.5% for ASCVD, ≥10% for RRS‐A and RRS‐B) were compared.ResultsAmong 713 women, 290 (41%) had elevated Lp(a); however, LDL‐C and Lp(a) were weakly correlated (r = 0.08). Significant discordance was observed between abnormal LDL‐C and Lp(a) levels (McNemar P = 0.03). There was moderate correlation between RRS‐A and ASCVD risk (r = 0.71, P < 0.001), and Bland‐Altman plot showed diminished correlation with increased risk. More patients met treatment threshold by ASCVD risk estimation, but nearly 1 out of 20 patients met treatment threshold by RRS‐A but not ASCVD score.ConclusionsThere is high prevalence of elevated Lp(a) among women presenting to Heart Centers for Women. Although traditional risk markers such as elevated LDL‐C or high ASCVD risk may be absent in some women, elevated Lp(a) may identify patients who may benefit from aggressive risk‐factor modification and pharmacologic therapy.
Clinical Outcome of First‐ vs Second‐Generation DES According to DAPT Duration: Results of ARCTIC‐Generation
Authors: Collet Jean‐Philippe , Silvain Johanne , Kerneis Mathieu , Cuisset Thomas , Meneveau Nicolas , Boueri Ziad , Barthélémy Olivier , Rangé Grégoire , Cayla Guillaume , Belle Eric Van , Elhadad Simon , Carrié Didier , Caussin Christophe , Rousseau Hélène , Aubry Pierre , Monségu Jacques , Sabouret Pierre , O'Connor Stephen A. , Abtan Jérémie , Saint‐Etienne Christophe , Beygui Farzin , Vicaut Eric , Montalescot Gilles ,   for the ARCTIC Investigators
Published: February 2016

ABSTRACTThere is an apparent benefit with extension of dual antiplatelet therapy (DAPT) beyond 1 year after implantation of drug‐eluting stents (DES). Assessment by a Double Randomization of a Conventional Antiplatelet Strategy vs a Monitoring‐Guided Strategy for Drug‐Eluting Stent Implantation, and of Treatment Interruption vs Continuation One Year After Stenting (ARCTIC)‐Generation assessed whether there is a difference of outcome between first‐ vs second‐generation DES and if there is an interaction with DAPT duration in the ARCTIC‐Interruption study. ARCTIC‐Interruption randomly allocated 1259 patients 1 year after stent implantation to a strategy of interruption of DAPT (n = 624), in which aspirin antiplatelet treatment only was maintained, or DAPT continuation (n = 635) for 6 to 18 additional months. The primary endpoint was the composite of death, myocardial infarction, stent thrombosis, stroke, or urgent revascularization. A total of 520 and 722 patients received a first‐ and a second‐generation DES, respectively. After a median follow‐up of 17 months (interquartile range, 15–18 months) after randomization, the primary endpoint occurred in 32 (6.2%) and 19 (2.6%) patients with first‐ and second‐generation DES, respectively (hazard ratio: 2.31, 95% confidence interval: 1.31‐4.07, P = 0.004). This was observed irrespective of the strategy of interruption or continuation of DAPT and timing of study recruitment. Major bleeding events occurred in 4 (0.8%) and 3 patients (0.4%) with first‐ and second‐generation DES, respectively (hazard ratio: 1.79, 95% confidence interval: 0.40‐8.02, P = 0.44). Results did not change after multiple adjustments for potential confounding variables. ARCTIC‐Generation showed worse clinical outcome with first‐ vs second‐generation DES, a difference that appeared to persist even with prolonged DAPT.
Young investigator challenge: Validation and optimization of immunohistochemistry protocols for use on cellient cell block specimens
Authors: Sauter Jennifer L. , Grogg Karen L. , Vrana Julie A. , Law Mark E. , Halvorson Jennifer L. , Henry Michael R. 
Published: February 2016

BACKGROUNDThe objective of the current study was to establish a process for validating immunohistochemistry (IHC) protocols for use on the Cellient cell block (CCB) system.METHODSThirty antibodies were initially tested on CCBs using IHC protocols previously validated on formalin‐fixed, paraffin‐embedded tissue (FFPE). Cytology samples were split to generate thrombin cell blocks (TCB) and CCBs. IHC was performed in parallel. Antibody immunoreactivity was scored, and concordance or discordance in immunoreactivity between the TCBs and CCBs for each sample was determined. Criteria for validation of an antibody were defined as concordant staining in expected positive and negative cells, in at least 5 samples each, and concordance in at least 90% of the samples total. Antibodies that failed initial validation were retested after alterations in IHC conditions.RESULTSThirteen of the 30 antibodies (43%) did not meet initial validation criteria. Of those, 8 antibodies (calretinin, clusters of differentiation [CD] 3, CD20, CDX2, cytokeratin 20, estrogen receptor, MOC‐31, and p16) were optimized for CCBs and subsequently validated. Despite several alterations in conditions, 3 antibodies (Ber‐EP4, D2‐40, and paired box gene 8 [PAX8]) were not successfully validated.CONCLUSIONSNearly one‐half of the antibodies tested in the current study failed initial validation using IHC conditions that were established in the study laboratory for FFPE material. Although some antibodies subsequently met validation criteria after optimization of conditions, a few continued to demonstrate inadequate immunoreactivity. These findings emphasize the importance of validating IHC protocols for methanol‐fixed tissue before clinical use and suggest that optimization for alcohol fixation may be needed to obtain adequate immunoreactivity on CCBs. Cancer (Cancer Cytopathol) 2016;124:89‐99. © 2016 American Cancer Society.