bluuebunny/crossref_metadata_2025_split huggingface dataset:
“Spontaneous” Ambient Temperature Dehydrocoupling of Aromatic Amine–Boranes
Authors: Helten Holger , Robertson Alasdair P. M. , Staubitz Anne , Vance James R. , Haddow Mairi F. , Manners Ian 
Published: March 2012

AbstractThe dehydrocoupling/dehydrogenation behavior of primary arylamine–borane adducts ArNH2⋅BH3 (3 a–c; Ar=a: Ph, b: p‐MeOC6H4, c: p‐CF3C6H4) has been studied in detail both in solution at ambient temperature as well as in the solid state at ambient or elevated temperatures. The presence of a metal catalyst was found to be unnecessary for the release of H2. From reactions of 3 a,b in concentrated solutions in THF at 22 °C over 24 h cyclotriborazanes (ArNH‐BH2)3 (7 a,b) were isolated as THF adducts, 7 a,b⋅THF, or solvent‐free 7 a, which could not be obtained via heating of 3 a–c in the melt. The μ‐(anilino)diborane [H2B(μ‐PhNH)(μ‐H)BH2] (4 a) was observed in the reaction of 3 a with BH3⋅THF and was characterized in situ. The reaction of 3 a with PhNH2 (2 a) was found to provide a new, convenient method for the preparation of dianilinoborane (PhNH)2BH (5 a), which has potential generality. This observation, together with further studies of reactions of 4 a, 5 a, and 7 a,b, provided insight into the mechanism of the catalyst‐free ambient temperature dehydrocoupling of 3 a–c in solution. For example, the reaction of 4 a with 5 a yields 6 a and 7 a. It was found that borazines (ArN‐BH)3 (6 a–c) are not simply formed via dehydrogenation of cyclotriborazanes 7 a–c in solution. The transformation of 7 a to 6 a is slowly induced by 5 a and proceeds via regeneration of 3 a. The adducts 3 a–c also underwent rapid dehydrocoupling in the solid state at elevated temperatures and even very slowly at ambient temperature. From aniline–borane derivative 3 c, the linear iminoborane oligomer (p‐CF3C6H4)N[BH‐NH(p‐CF3C6H4)]2 (11) was obtained. The single‐crystal X‐ray structures of 3 a–c, 5 a, 7 a, 7 b⋅THF, and 11 are discussed.
Coronary Revascularization in Women
Authors: Lundberg Gina , King Spencer 
Published: March 2012

AbstractHistorically, mortality rates have been higher in women than in men for both PCI and CABG. Recent registries and studies have shown that women have mortality rates similar to men after correcting for age and comorbidities. The gender gap is narrowing with respect to outcomes for women with both PCI and CABG. Revascularization with PCI and CABG in women with stable angina (SA), unstable angina (UA), non ST‐elevation myocardial infarction (NSTEMI), and ST‐elevation myocardial infarction (STEMI) will all be reviewed in light of the most recent studies and registries. © 2012 Wiley Periodicals, Inc.All American College of Cardiology Foundation/American Heart Association guidelines are published in the Journal of the American College of Cardiology and Circulation, and are available online at www.cardiosource.com and http://my.americanheart.org/professional/Statements Guidelines. The authors have no funding, financial relationships, or conflicts of interest to disclose.
Effects of Cyclic Lipodepsipeptide Structural Modulation on Stability, Antibacterial Activity, and Human Cell Toxicity
Authors: Bionda Nina , Stawikowski Maciej , Stawikowska Roma , Cudic Maré , López‐Vallejo Fabian , Treitl Daniela , Medina‐Franco José , Cudic Predrag 
Published: March 2012

AbstractBacterial infections are becoming increasingly difficult to treat due to the development and spread of antibiotic resistance. Therefore, identifying novel antibacterial targets and new antibacterial agents capable of treating infections by drug‐resistant bacteria is of vital importance. The structurally simple yet potent fusaricidin or LI‐F class of natural products represents a particularly attractive source of candidates for the development of new antibacterial agents. We synthesized 18 fusaricidin/LI‐F analogues and investigated the effects of structure modification on their conformation, serum stability, antibacterial activity, and toxicity toward human cells. Our findings show that substitution of an ester bond in depsipeptides with an amide bond may afford equally potent analogues with improved stability and greatly decreased cytotoxicity. The lower overall hydrophobicity/amphiphilicity of amide analogues in comparison with their parent depsipeptides, as indicated by HPLC retention times, may explain the dissociation of antibacterial activity and human cell cytotoxicity. These results indicate that amide analogues may have significant advantages over fusaricidin/LI‐F natural products and their depsipeptide analogues as lead structures for the development of new antibacterial agents.
Interfacial Layering of a Room‐Temperature Ionic Liquid Thin Film on Mica: A Computational Investigation
Authors: Dragoni Daniele , Manini Nicola , Ballone Pietro 
Published: March 2012

AbstractThe structure of a thin (4 nm) [bmim][Tf2N] film on mica was studied by molecular dynamics simulations using an empirical force field. Interfacial layering at T=300 K and at T=350 K is investigated by determining the number‐ and charge‐density profiles of [bmim][Tf2N] as a function of distance from mica, and by computing the normal force Fz opposing the penetration of the ionic liquid film by a spherical nanometric tip interacting with [bmim][Tf2N] atoms by a short‐range potential. The results show that layering is important but localised within ∼1 nm from the interface. The addition of a surface charge on mica, globally neutralised by an opposite charge on the [bmim][Tf2N] side, gives rise to low‐amplitude charge oscillations extending through the entire film. However, outside a narrow interfacial region, the resistance of the [bmim][Tf2N] film to penetration by the mesoscopic tip is only marginally affected by the charge at the interface. The results obtained here for [bmim][Tf2N]/mica are similar to those obtained using the same method for the [bmim][Tf2N]/silica interface, and agree well with experimental force–distance profiles measured on the latter interface at ambient conditions.
Nanocarbon Composites and Hybrids in Sustainability: A Review
Authors: Vilatela Juan J. , Eder Dominik 
Published: March 2012

AbstractThere is an ever‐growing need to protect our environment by increasing energy efficiency and developing “clean” energy sources. These are global challenges, and their resolution is vital to our energy security. Although many conventional materials, such as metals, ceramics, and plastics, cannot fulfil all requirements for these new technologies, many material combinations can offer synergistic effects that create improved and even new properties. The implementation of nanocarbons, such as graphene and carbon nanotubes, into nanocomposites and, more recently, into the new class of hybrids, are very promising examples. In contrast to classical nanocomposites, where a low volume fraction of the carbon component is mixed into a polymer or ceramic matrix, hybrids are materials in which nanocarbon is coated with a thin layer of the functional compound, which introduces the interface as a powerful new parameter. Based on interfacial charge and energy transfer processes, nanocarbon hybrids have shown increased sensitivities in gas sensors, improved efficiencies in photovoltaics, superior activities in photocatalysts, and enhanced capacities in supercapacitors. This review compares the characteristics and potentials of both nanocarbon composites and hybrids, highlights recent developments in their synthesis and discusses key challenges for their use in various energy applications.
Synthesis of Nitrogen‐Rich Mesoporous Carbon Nitride with Tunable Pores, Band Gaps and Nitrogen Content from a Single Aminoguanidine Precursor
Authors: Talapaneni Siddulu N. , Mane Gurudas P. , Mano Ajayan , Anand Chokkalingam , Dhawale Dattatray S. , Mori Toshiyuki , Vinu Ajayan 
Published: March 2012

AbstractHighly ordered mesoporous carbon nitride (CN) with an extremely high nitrogen content and tunable pore diameters was synthesized by using a new precursor with a high nitrogen content, aminoguanidine hydrochloride and mesoporous silica SBA‐15 with different pore diameters as hard templates. Surprisingly, the N/C ratio of the prepared mesoporous CN (MCN‐4: 1.80) was considerably higher than that of the theoretically predicted C3N4 nanostructures (1.33). This is mainly due to the fact that the CN precursor easily undergoes polymerization at high temperature and affords a highly stable polymer composed of a diamino‐s‐tetrazine moiety with a six‐membered aromatic ring containing six nitrogen atoms that are linked trigonally with the nitrogen atoms. The obtained materials were thoroughly characterized by means of XRD, nitrogen adsorption, high resolution TEM, electron energy loss spectra, high resolution SEM, X‐ray photoelectron spectroscopy, FTIR, and C, N, O, and S analysis. The results show that the MCN‐4 materials possess a well‐ordered mesoporous structure similar to SBA‐15 with a high specific surface area and tunable band gap in the range of 2.25–2.49 eV. Interestingly, the pore diameter of the materials can be finely tuned from 3.1–5.8 nm by increasing the pore diameter of the hard‐template SBA‐15. The reaction temperature plays a critical role for the formation of MCN, and we found that 400 °C is the best condition to obtain MCN‐4 with a high nitrogen content. We have further investigated the catalytic application of the MCN‐4 materials towards Friedel–Crafts hexanoylation of benzene and compared the results with the mesoporous CN with less nitrogen content (MCN‐1) and nonporous CN. Among the materials studied, MCN‐4 showed the highest activity, affording a high yield of hexanophenone within a few hours, which is mainly due to the presence of free amine groups on the wall structure of MCN‐4.
Atomic Layer Deposition of HfO2 Thin Films Employing a Heteroleptic Hafnium Precursor
Authors: Xu Ke , Milanov Andrian P. , Parala Harish , Wenger Christian , Baristiran‐Kaynak Canan , Lakribssi Kaoutar , Toader Teodor , Bock Claudia , Rogalla Detlef , Becker Hans‐Werner , Kunze Ulrich , Devi Anjana 
Published: March 2012

AbstractThe application of a heteroleptic hafnium amide‐guanidinate precursor for the deposition of HfO2 thin films via a water‐assisted atomic layer deposition (ALD) process is demonstrated for the first time. HfO2 films are grown in the temperature range 100–300 °C using the compound [Hf(NMe2)2(NMe2‐Guan)2] (1). This compound shows self‐limiting ALD‐type growth characteristics with growth rates of the order of 1.0–1.2 Å per cycle in the temperature range 100–225 °C. The saturation behavior and a linear dependence on film thickness as a function of number of cycles are verified at various temperatures within the ALD window. The as‐deposited HfO2 films are characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy (RBS), X‐ray photoelectron spectroscopy (XPS), and electrical measurements. For a direct comparison of the precursor performance with that of the parent alkyl amide [Hf(NMe2)4] (2), ALD experiments are also performed employing compound 2 under similar process conditions, and in this case no typical ALD characteristics are observed.
Initial Stage Growth during Plasma‐Enhanced Atomic Layer Deposition of Cobalt
Authors: Lee Han‐Bo‐Ram , Park Yong Jun , Baik Sunggi , Kim Hyungjun 
Published: March 2012

AbstractThe initial growth of Co thin films during plasma‐enhanced atomic layer deposition (PE‐ALD) is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), and synchrotron radiation X‐ray reflectivity (SR‐XRR). For the PE‐ALD of Co, CoCp2 and NH3 plasma were used as precursor and reactant, respectively. From XRR simulation, the growth rate at the initial stage of growth did not linearly increase with growth cycles, showing deviation from ideal ALD growth. The low density of PE‐ALD‐produced Co film up to 100 cycles is observed from XRR and confirmed by AFM and SEM results. The growth behavior of Co is explained by island growth under substrate‐inhibited growth mode.
Application of Carbon Nanotubes Directly Grown on Aluminum Foils as Electric Double Layer Capacitor Electrodes
Authors: Khavrus Vyacheslav O. , Weiser Mathias , Fritsch Marco , Ummethala Raghunandan , Salvaggio Maria Grazia , Schneider Michael , Kusnezoff Mihails , Leonhardt Albrecht 
Published: March 2012

AbstractCarbon nanotubes (CNTs) are directly grown by catalytic (C)CVD on Al foils with various surface morphologies to make hybrid electrodes for electric double layer capacitors (EDLCs). A simple drop‐coating procedure is used for the deposition of the Fe/Al‐based catalyst. It is found that the surface topography of the Al foil is a governing factor for the growth of CNTs, their alignment, and adhesion to the current collector. Prepared electrodes achieve a specific capacitance up to 11.2 F g−1, which is found to be weakly sensitive to the alignment of the CNTs. Discussion of parameters that influence the properties of the resulting EDLCs is presented.
Physical activity is related to insulin sensitivity in children and adolescents, independent of adiposity: a review of the literature
Authors: Berman Laura J. , Weigensberg Marc J. , Spruijt‐Metz Donna 
Published: March 2012

SummaryIn adults, there is evidence that physical activity effectively improves insulin sensitivity regardless of adiposity. Whether this is also the case in children and adolescents is less clear. Clarifying this matter may help to identify the best outcomes to target in exercise programs for these age groups, where changes in adiposity may not always be desirable or realistic. A review of the literature was conducted on studies that examined the relationships of physical activity, cardiorespiratory fitness and strength with insulin sensitivity independent of adiposity in children and adolescents. Experimental (intervention) and correlational (longitudinal and cross‐sectional) studies on participants ages 18 years and younger were identified. A total of 42 studies were included in this review. Sample sizes in the studies ranged from 14 to 4955 participants, with individual ages ranging from 5 to 19 years. A significant relationship with insulin sensitivity existed in 78% of studies on physical activity, 69% of studies on cardiorespiratory fitness and 66% of studies on strength. In studies that examined both physical activity and cardiorespiratory fitness concurrently, evidence suggests that they are both correlated with insulin sensitivity independent of adiposity, especially when physical activity is at higher intensities. However, the strength of this relationship might be influenced by study design, measurement techniques and participant characteristics. This is the first review of its type to take research design into account and to examine study outcomes according to participant ethnicity, gender, age, pubertal status and weight status. Copyright © 2012 John Wiley & Sons, Ltd.
Erosion of soils due to rainfall impact – an interpolation method
Authors: Parlange J‐Y. , Hogarth W. L. , Heng B. C. P. , Sander G. C. , Barry D. A. , Brovelli A. , Jomaa S. , Parlange M. B. , Hairsine P. B. , Steenhuis T. S. , van Meerveld H. J. , Rose C. W. 
Published: March 2012

ABSTRACTAn approximate analytical solution of the Hairsine–Rose model of erosion is obtained by interpolation of asymptotic expressions for large times and great distances. The solution, when erosion is initiated by rainfall impact, is both simple and accurate. The results are illustrated by comparison with a numerical solution. Copyright © 2012 John Wiley & Sons, Ltd.
Pd‐ and/or Au‐Loaded Nb‐ and V‐Doped Macro‐Mesoporous TiO2 Supports as Catalysts for the Total Oxidation of VOCs
Authors: Barakat Tarek , Rooke Joanna C. , Franco Manuel , Cousin Renaud , Lamonier Jean‐François , Giraudon Jean‐Marc , Su Bao‐Lian , Siffert Stéphane 
Published: March 2012

AbstractTwo sets of hierarchically structured titania (TiO2) supports were doped with group V metal oxides, one with Nb2O5 and the other with V2O5. It was noted that before thermal treatment the prepared materials were amorphous, whereas after calcination at 400 °C the XRD patterns showed well‐defined peaks that indicated that the materials were a crystalline anatase phase. Treating these supports at high temperatures was followed by a decrease in their Brunauer–Emmett–Teller (BET) specific surface area values. The catalytic performance of these materials and their corresponding noble metal (Pd and Au) loaded catalysts was investigated in the total oxidation of toluene. It was clear that after noble‐metal loading, the activity was much higher than that of the unloaded supports, with Pd5VTi and PdAu3NbTi offering the best performances in the oxidation reaction. XRD patterns of the noble‐metal‐loaded catalysts showed peaks associated with the presence of metallic gold particles and palladium species on the supports; diffuse‐reflectance UV/Vis spectra also showed the presence of these noble metals, as well as a reduction in the intensities of the bands relative to those in the spectra of the unloaded doped titania supports, which is due to the metal–support interactions. Spectra obtained with this characterization technique also showed a shift of the Au bands to higher wavelengths, which should be correlated to changes in the size of the gold particles.
Cage Rearrangements in Dodecanuclear Co–Pt Dicarbido Clusters Promoted by Redox Reactions
Authors: Femoni Cristina , Iapalucci Maria Carmela , Longoni Giuliano , Zacchini Stefano , Fedi Serena , Fabrizi de Biani Fabrizia 
Published: March 2012

AbstractThe chemical reduction of [Co8Pt4C2(CO)24]2– ([1]2–) with Na/naphthalene results, after workup, in the isolation of either [Co10Pt2C2(CO)22]4– ([2]4–) or [Co8Pt4C2(CO)20]4– ([3]4–), depending on the experimental conditions. All these species undergo several chemical and/or electrochemical redox reactions, disclosing the existence of structurally related dodecanuclear clusters [1]n– (n = 0–4), [2]n– (n = 2–6) and [3]n–(n = 1–7). In the attempt to isolate more reduced species,[1]n–, [2]n– and [3]n– undergo structural rearrangements resulting, among others, in the formation of the new species [Co10–xPt2+xC2(CO)24]2– ([4]2–) (x = 0–2) structurally related to [1]2–. These dodecanuclear M12C2 dicarbido clusters are not isostructural and differ in the metal composition and/or the number of CO ligands. Nevertheless, they can be readily interconverted even if the interconversion reactions are not straightforward.
An Electron‐Density‐Based Study on the Ionic Reactivity of 1,3‐Azoles
Authors: Otero Nicolás , Estévez Laura , Mandado Marcos , Mosquera Ricardo A. 
Published: March 2012

AbstractBasic processes for the ionic chemistry of 1,3‐azoles (protonation, nitration, hydride addition, and deprotonation) have been studied by analyzing B3LYP/6‐311++G(2d,2p) 6d electron densities using the Quantum Theory of Atoms in Molecules (QTAIM) and delocalization indices in the gas phase and in aqueous solution modeled with the Polarizable Continuum Model (PCM) method. The most stable protonation site is N3 in all cases, and this takes place without a significant change in electron delocalization, whereas C5 is the preferred site for electrophilic substitution. Activating and deactivating effects on the carbon atoms of the imidazole ring were tested by analyzing the variation of atomic properties introduced by amino and nitro substituents, respectively. The largest activation was observed for C5 in 4‐aminoimidazole. C2 is the most favored site for hydridation in all 1,3‐azoles, which always results in loss of ring planarity and reduced electron delocalization in the ring. PCM calculations allow the experimentally observed preferred deprotonation C‐site in water for these compounds to be modeled and reproduced. In all anions, QTAIM charges do not keep in line with the resonance forms; whereas QTAIM describes deprotonated carbon atoms as positive or nearly neutral in the gas phase, they should display negative charge according to the resonance model.
Explaining the stress‐inducing effects of nicotine to cigarette smokers
Authors: Parrott Andrew C. , Murphy Rachel S. 
Published: March 2012

AimsTo explain how nicotine dependency causes mood fluctuation and increases daily stress.MethodsProspective studies show that taking‐up smoking leads to higher stress and depression. Cross‐sectional studies show that adult smokers report more irritability, stress and depression than non‐smokers. Prospective studies show that smoking cessation leads to enduring mood gains. The adverse mood effects of nicotine dependency are explained by the deprivation reversal model. In between cigarettes, most smokers experience subtle abstinence symptoms, and cumulatively these can increase everyday stress. Hence, adolescents who take up smoking become more stressed, and quitting reduces stress. An explanatory leaflet to explain this model was empirically assessed with tobacco smokers.ResultsIn a cohort study of 82 cigarette smokers, knowledge levels were significantly enhanced by the explanatory leaflet, and this understanding was maintained 1 week later. Hence, normal cigarette smokers can understand the adverse mood consequences of nicotine addiction. The information leaflet could prove useful for tobacco‐education packages in schools, and smoking‐cessation packages with adults.ConclusionsThe deprivation reversal model can be easily described using a simple leaflet. It explains how nicotine dependency can cause mood fluctuation, and outlines the psychological benefits of quitting. Copyright © 2012 John Wiley & Sons, Ltd.
Epigallocatechin gallate, cerebral blood flow parameters, cognitive performance and mood in healthy humans: a double‐blind, placebo‐controlled, crossover investigation
Authors: Wightman Emma L. , Haskell Crystal F. , Forster Joanne S. , Veasey Rachel C. , Kennedy David O. 
Published: March 2012

ObjectiveThe aim of the study was to assess the effects of oral ingestion of the ‘green tea’ polyphenol epigallocatechin gallate (EGCG) on cognitive performance, mood and localised cerebral blood flow (CBF) parameters in healthy human adults.MethodIn this double‐blind, placebo‐controlled, crossover study, 27 healthy adults received placebo and two doses (135 and 270 mg) of EGCG in counterbalanced order on separate days. Following a 45‐min resting absorption period, participants performed a selection of computerised cognitive tasks that activate the frontal cortex for a further 42 min. CBF and haemodynamics, as indexed by concentration changes in oxygenated and deoxygenated haemoglobin, were assessed in the frontal cortex throughout the post‐treatment period using Near‐infrared spectroscopy (NIRS).ResultsDuring the post‐dose task performance period, the administration of 135 mg EGCG resulted in reduced CBF in the frontal cortex, as indexed by significantly lower concentrations of both oxygenated and total haemoglobin, in comparison with placebo. Heart rate was significantly reduced from pre dose to post dose across all treatments. No significant differences were observed for the level of deoxygenated haemoglobin or on any of the cognitive performance/mood measures.ConclusionsThese results demonstrate that a single dose of orally administered EGCG can modulate CBF parameters in healthy humans but that this is not associated with changes in cognitive performance or mood. Copyright © 2012 John Wiley & Sons, Ltd.