bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proton‐Exchange Equilibrium between Bases and [BMIm][BF4]: An Electrochemical Procedure to Evaluate the Presence of Carbenes for Synthetic Applications
Authors: Chiarotto Isabella , Feroci Marta , Forte Gianpiero , Orsini Monica , Inesi Achille 
Published: July 2014

AbstractThe ability of a base to yield an N‐heterocyclic carbene (NHC) in a base–ionic‐liquid solution is investigated by using an electrochemical procedure. Accordingly, the equilibrium of proton exchange between different bases (1,5‐diazabicyclo[5.4.0]undec‐5‐ene, 1,1,2,3,3‐pentaisopropylguanidine, Cs2CO3, 2,4,6‐trimethylpyridine, and triethylamine) and the 1‐butyl‐3‐methylimidazolium (BMIm+) cation was studied with the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]) as a solvent. The concentration of NHC, in the different base–[BMIm][BF4] systems, is derivable from the anodic peak current (related to the oxidation of NHC) of the voltammograms recorded in base–[BMIm][BF4] solutions. The electrochemical procedure allows utilisation of base–[BMIm][BF4] solutions as a media that is capable of inducing NHC‐catalysed syntheses. The NHC‐catalysed oxidation of aldehydes to esters is selected as a model reaction. The results of the syntheses are in accordance with electrochemical forecasts.
Ruthenium Porphyrins with Axial π‐Conjugated Arylamide and Arylimide Ligands
Authors: Law Siu‐Man , Chen Daqing , Chan Sharon Lai‐Fung , Guan Xiangguo , Tsui Wai‐Man , Huang Jie‐Sheng , Zhu Nianyong , Che Chi‐Ming 
Published: July 2014

AbstractA series of ruthenium porphyrins [RuIV(por)(NHY)2] and [RuVI(por)(NY)2] bearing axially coordinated π‐conjugated arylamide and arylimide ligands, respectively, have been synthesized. The crystal structures of [RuIV(tmp)(NHY)2] (tmp=5,10,15,20‐tetramesitylporphyrinato(2−)) with Y=4′‐methoxy‐biphenyl‐4‐yl (ArAr‐p‐OMe), 4′‐chloro‐biphenyl‐4‐yl (ArAr‐p‐Cl), and 9,9‐dibutyl‐fluoren‐2‐yl (Ar^Ar) show axial RuN(arylamide) distances of 1.978(4), 1.971(6), and 1.985(13) Å, respectively. [RuIV(tmp)(NH{Ar^Ar})2] is an example of metalloporphyrins that bind an arylamide ligand featuring a co‐planar biphenyl unit. The [RuIV(por)(NHY)2] complexes show a quasi‐reversible reduction couple or irreversible reduction wave attributed to RuIV→RuIII with Epc from −1.06 to −1.40 V versus Cp2Fe+/0 and an irreversible oxidation wave with Epa from −0.04 to 0.19 V versus Cp2Fe+/0. Reaction of the [RuIV(por)(NHY)2] with bromine afforded [RuIV(por)(NHY)Br]. PhI(OAc)2 oxidation of the [RuIV(por)(NHY)2] gave [RuVI(por)(NY)2]; the latter can be prepared from reaction of [RuII(por)(CO)] with aryl azides N3Y. The crystal structure of [RuVI(tmp)(N{ArAr‐p‐OMe})2] features RuN(arylimide) distances of 1.824(5) and 1.829(5) Å. Alkene aziridination and CH amination catalyzed by “[RuII(tmp)(CO)]+π‐conjugated aryl azides”, or mediated by [RuVI(por)(NY)2] with Y=biphenyl‐4‐yl (ArAr) and ArAr‐p‐Cl, gave aziridines and amines in moderate yields. The electronic structure of [RuVI(por)(NY)2] was examined by DFT calculations.
A Unique Architecture Based on 1 D Semiconductor, Reduced Graphene Oxide, and Chalcogenide with Multifunctional Properties
Authors: Mukherjee Bratindranath , Gupta Satyajit , Peterson Aaron , Imahori Hiroshi , Manivannan Ayyakkannu , Subramanian Vaidyanathan (Ravi) 
Published: July 2014

AbstractA unique heterostructured optoelectronic material (HOM), consisting of a reduced graphene oxide (RGO) layer with spatially distributed CdS, suspended by zinc oxide (ZnO) nanorods, is presented. The key features of this HOM are the assembly of the components in a manner so as to realize an effective integration between the constituents and the ability to modify the electronic properties of the RGO. For the first time, the location of RGO (as a suspended layer) along with the tuning of its charge‐transport properties (n‐/p‐type) and its influence on the photo(electro)chemical processes has been examined systematically by using this ZnO/RGO/CdS HOM as a case study. The n‐type RGO interlayer facilitates >100 % increase in the photocurrent density and 25 % increase in the photodegradation of a dye, compared to ZnO/CdS, thus demonstrating its multifunctionality. At 3.2 mA cm−2, this HOM architecture helps to achieve the highest photocurrent density utilizing ZnO, RGO, and CdS as building blocks in any form. The work is significant for the following reasons: i) other one dimensional (1D) oxides/chalcogenides or 1D oxides/dyes may be designed with similar architectures; ii) HOMs with tunable optical absorbance and charge‐transport properties could be realized; iii) related application areas (e.g., sensing or solar fuel generation) should be greatly benefited.
Engineered Electron‐Transfer Chain in Photosystem 1 Based Photocathodes Outperforms Electron‐Transfer Rates in Natural Photosynthesis
Authors: Kothe Tim , Pöller Sascha , Zhao Fangyuan , Fortgang Philippe , Rögner Matthias , Schuhmann Wolfgang , Plumeré Nicolas 
Published: July 2014

AbstractPhotosystem 1 (PS1) triggers the most energetic light‐induced charge‐separation step in nature and the in vivo electron‐transfer rates approach 50 e− s−1 PS1−1. Photoelectrochemical devices based on this building block have to date underperformed with respect to their semiconductor counterparts or to natural photosynthesis in terms of electron‐transfer rates. We present a rational design of a redox hydrogel film to contact PS1 to an electrode for photocurrent generation. We exploit the pH‐dependent properties of a poly(vinyl)imidazole Os(bispyridine)2Cl polymer to tune the redox hydrogel film for maximum electron‐transfer rates under optimal conditions for PS1 activity. The PS1‐containing redox hydrogel film displays electron‐transfer rates of up to 335±14 e− s−1 PS1−1, which considerably exceeds the rates observed in natural photosynthesis or in other semiartificial systems. Under O2 supersaturation, photocurrents of 322±19 μA cm−2 were achieved. The photocurrents are only limited by mass transport of the terminal electron acceptor (O2). This implies that even higher electron‐transfer rates may be achieved with PS1‐based systems in general.
The Local Atomic Structures of Liquid CO at 3.6 GPa and Polymerized CO at 0 to 30 GPa from High‐Pressure Pair Distribution Function Analysis
Authors: Rademacher Nadine , Bayarjargal Lkhamsuren , Morgenroth Wolfgang , Winkler Björn , Ciezak‐Jenkins Jennifer , Batyrev Iskander G. , Milman Victor 
Published: July 2014

AbstractThe local atomic structures of liquid and polymerized CO and its decomposition products were analyzed at pressures up to 30 GPa in diamond anvil cells by X‐ray diffraction, pair distribution function (PDF) analysis, single‐crystal diffraction, and Raman spectroscopy. The structural models were obtained by density functional calculations. Analysis of the PDF of a liquid CO‐rich phase revealed that the local structure has a pronounced short‐range order. The PDFs of polymerized amorphous CO at several pressures revealed the compression of the molecular structure; covalent bond lengths did not change significantly with pressure. Experimental PDFs could be reproduced with simulations from DFT‐optimized structural models. Likely structural features of polymerized CO are thus 4‐ to 6‐membered rings (lactones, cyclic ethers, and rings decorated with carbonyl groups) and long bent chains with carbonyl groups and bridging atoms. Laser heating polymerized CO at pressures of 7 to 9 GPa and 20 GPa resulted in the formation of CO2.
Reactivity of an Intramolecular Fluorophosphonium Fluoroborate
Authors: Ekkert Olga , Caputo Christopher B. , Pranckevicius Conor , Daniliuc Constantin G. , Kehr Gerald , Erker Gerhard , Stephan Douglas W. 
Published: July 2014

AbstractThe reactions of the intramolecular frustrated Lewis pair‐adduct Ph2PC(p‐Tol)C(C6F5)B(C6F5)2(CNtBu) with XeF2 gave Ph2P(F)C(p‐Tol)C(C6F5)B(F)(C6F5)2 (3). This species reacts with two equivalents of Al(C6F5)3⋅C7H8 producing the salt, [Ph2P(F)C(p‐Tol)C(C6F5)B(C6F5)2][F(Al(C6F5)3)2] (4), whereas reaction with HSiEt3/B(C6F5)3 gave Ph2P(F)C(p‐Tol)C(H)B(C6F5)3 (5). The photolysis of 3 resulted in aromatization affording the phenanthralene derivative Ph2P(F)C(p‐Tol(o‐C6F4))CB(F)(C6F5)2 (6).
DNA Aptamers are Functional Molecular Recognition Sensors in Protic Ionic Liquids
Authors: Machado Isabel , Özalp Veli Cengiz , Rezabal Elixabete , Schäfer Thomas 
Published: July 2014

AbstractThe function and structural changes of an AMP molecular aptamer beacon and its molecular recognition capacity for its target, adenosine monophosphate (AMP), was systematically explored in solution with a protic ionic liquid, ethylammonium nitrate (EAN). It could be proven that up to 2 M of EAN in TBS buffer, the AMP molecular aptamer beacon was still capable of recognizing AMP while also maintaining its specificity. The specificity was proven by using the guanosine monophosphate (GMP) as target; GMP is structurally similar to AMP but was not recognized by the aptamer. We also found that in highly concentrated EAN solutions the overall amount of double stranded DNA formed, as well as its respective thermal stability, diminished gradually, but surprisingly the hybridization rate (kh) of single stranded DNA was significantly accelerated in the presence of EAN. The latter may have important implications in DNA technology for the design of biosensing and DNA‐based nanodevices in nonconventional solvents, such as ionic liquids.
Invoking Pairwise Interactions in Water‐Promoted Diels–Alder Reactions by using Ionic Liquids as Cosolvents
Authors: Manna Arpan , Kumar Anil 
Published: July 2014

AbstractRate constants and derived activation parameters of organic reactions in aqueous media, in particular Diels–Alder reactions, are sensitive to the presence of cosolvents in water. To enhance the solubility window of water, we introduced ionic liquids as cosolvents in the aqueous Diels–Alder reaction between anthracene‐9‐carbinol and N‐ethylmaleimide. The reactive potentials of the organic compounds are parameterized by using semi‐empirical quantum chemical methods. The principle of Savage–Wood additivity of group interactions is used to quantify the pairwise group interactions among chemically inert ionic liquids and organic reactants, both at initial and transition states of the reaction. The present approach shows promise, as the use of simple calculations from easily available kinetic data can help researchers to understand the versatility of green ionic‐liquid alternatives to volatile organic solvents.
Preventing the Dissolution of Lithium Polysulfides in Lithium–Sulfur Cells by using Nafion‐coated Cathodes
Authors: Oh Soo Jung , Lee Jun Kyu , Yoon Woo Young 
Published: July 2014

AbstractThe principal drawback of lithium–sulfur batteries is the dissolution of long‐chain lithium polysulfides into the electrolyte, which limits cycling performance. To overcome this problem, we focused on the development of a novel cathode as well as anode material and designed Nafion‐coated NiCrAl/S as a cathode and lithium powder as an anode. Nafion‐coated NiCrAl/S cathode was synthesized using a two‐step dip‐coating technique. The lithium‐powder anode was used instead of a lithium‐foil anode to prohibit dendrite growth and to improve on the electrochemical behaviors. The cells showed an initial discharge capacity of about 900 mA g−1 and a final discharge capacity of 772 mA g−1 after 100 cycles at 0.1 C‐rate. Scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS) demonstrate that using the Nafion‐coated NiCrAl/S cathode can suppress the dissolution of long‐chain lithium polysulfides.
Withdrawal of BDNF from hippocampal cultures leads to changes in genes involved in synaptic function
Authors: Mariga Abigail , Zavadil Jiri , Ginsberg Stephen D. , Chao Moses V. 
Published: July 2014

ABSTRACTNeurotrophins play a crucial role in mediating neuronal survival and synaptic plasticity. A lack of trophic factor support in the peripheral nervous system (PNS) is associated with a transcription‐dependent programmed cell death process in developing sympathetic neurons. While most of the attention has been on events culminating in cell death in the PNS, the earliest events that occur after trophic factor withdrawal in the central nervous system (CNS) have not been investigated. In the CNS, brain‐derived neurotrophic factor (BDNF) is widely expressed and is released in an activity‐dependent manner to shape the structure and function of neuronal populations. Reduced neurotrophic factor support has been proposed as a mechanism to account for changes in synaptic plasticity during neurodevelopment to aging and neurodegenerative disorders. To this end, we performed transcriptional profiling in cultured rat hippocampal neurons. We used a TrkB ligand scavenger (TrkB‐FC) to sequester endogenous neurotrophic factor activity from hippocampal neurons in culture. Using a high‐density microarray platform, we identified a significant decrease in genes that are associated with vesicular trafficking and synaptic function, as well as selective increases in MAP kinase phosphatases. A comparison of these changes with recent studies of Alzheimer's disease and cognitive impairment in postmortem brain tissue revealed striking similarities in gene expression changes for genes involved in synaptic function. These changes are relevant to a wide number of conditions in which levels of BDNF are compromised. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 75: 173–192, 2015
Nanoparticle structure development in the gastro‐intestinal model fluid FaSSIFmod6.5 from several phospholipids at various water content relevant for oral drug administration
Authors: Khoshakhlagh Pooneh , Johnson Raphael , Nawroth Thomas , Langguth Peter , Schmueser Lars , Hellmann Nadja , Decker Heinz , Szekely Noemi Kinga 
Published: July 2014

The characteristics of intestinal model fluids were investigated at conditions, which simulate the passage from the middle to the end of the duodenum. The formation and decay of liposomes and micelles in model bile fluids were studied, because of their role as an intermediate host for the resolution and uptake of hydrophobic drugs (BCS classes II, IV). The conditions, which may influence the formation of these nanoparticulate intermediates were studied, i.e., the lipid composition of the bile, the preparation method, the time of the passage through the modelled duodenum segment and the concentration, which results from the variable dilution of the bile by mixing with the transfer medium representing the fluid arriving from the stomach. The variation of the lecithin entity revealed an equivalence of Egg–lecithin of a high purity (99%) with its main component 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine POPC, while 1,2‐di‐oleoyl‐sn‐glycero‐3‐phosphocholine DOPC resulted in a slight delay of the micelle‐liposome conversion. The FeSSIF preparation method was best with the sequential‐film method, while the bile‐film method yielded comparable results; the shake method showed a slightly different kinetics of the nanoparticle conversion. The time and concentration dependence of the formation and decay of lipidic nanoparticles indicates that these strongly depend on the passage time (speed) and bile dilution rate. The corresponding physiological conditions at healthy persons may vary in vivo individually and due to diseases. The studied conditions cover typical physiological conditions, which should be taken into consideration in the exploration of in vitro tests of formulations of hydrophobic drugs.Formation and decay of liposomes and micelles from bile in the duodenum was studied, due to their role as an intermediate for resolution and uptake of hydrophobic drugs (BCS II, IV). The physiological conditions studied may vary individually and due to diseases.
Regiospecific Synthesis of Substituted 2‐Nitrobenzaldehydes from Benzaldehydes through Palladium‐Catalyzed Chelation‐Assisted C–H Nitration
Authors: Zhang Wei , Wu Degui , Zhang Jian , Liu Yunkui 
Published: July 2014

AbstractA regiospecific synthesis of substituted 2‐nitrobenzaldehydes from substituted benzaldehydes has been developed that involves a three‐step process with palladium‐catalyzed chelation‐assisted C–H nitration as the key step. In the process, O‐methyl aldoxime serves as a removable directing group for the palladium‐catalyzed ortho‐nitration of substituted benzaldoximes and it can be removed in subsequent conversion of the resulting 2‐nitrobenzaldoximes into 2‐nitrobenzaldehydes.
Self‐report pain and symptom measures for primary dysmenorrhoea: A critical review
Authors: Chen C.X. , Kwekkeboom K.L. , Ward S.E. 
Published: July 2014

AbstractPrimary dysmenorrhoea (PD) is highly prevalent among women of reproductive age and it can have significant short‐ and long‐term consequences for both women and society as a whole. Validated symptom measures are fundamental for researchers to understand women's symptom experience of PD and to test symptom interventions. The objective of this paper was to critically review the content and psychometric properties of self‐report tools to measure symptoms of PD. Databases including PubMed, PsychoINFO, Cumulative Index of Nursing and Allied Health Literature, and Health and Psychosocial Instruments were searched for self‐report symptom measures that had been used among women with either PD or perimenstrual symptoms. A total of 15 measures met inclusion criteria and were included in the final analysis. The measures were categorized into generic pain measures, dysmenorrhoea‐specific measures, and tools designed to measure perimenstrual symptoms. These measures had varying degrees of comprehensiveness of symptoms being measured, relevance to PD, multidimensionality and psychometric soundness. No single measure was found to be optimal for use, but some dysmenorrhoea‐specific measures could be recommended if revised and further tested. Key issues in symptom measurement for PD are discussed. Future research needs to strengthen dysmenorrhoea‐specific symptom measures by including a comprehensive list of symptoms based on the pathogenesis of PD, exploring relevant symptom dimensions beyond symptom severity (e.g., frequency, duration, symptom distress), and testing psychometric properties of the adapted tools using sound methodology and diverse samples.
The relationship between cognitive performance and insulin resistance in non‐diabetic patients with mild cognitive impairment
Authors: Kim Tae‐Eun , Lee Dong Hyun , Kim Yoon‐Jeong , Mok Ji Oh , Kim Chul‐ Hee , Park Jeong‐Ho , Lee Tae‐Kyeong , Yoo Kwangsun , Jeong Yong , Lee Yunhwan , Park Sun Ah 
Published: July 2014

ObjectiveInsulin resistance (IR) is a distinct and early feature of type 2 diabetes mellitus and metabolic syndrome. IR is thought to play a vital role in cognitive impairment. We conducted this study to understand the early characteristics of cognitive dysfunctions attributable to IR.MethodsThis study included 85 consecutive non‐diabetic elderly participants with mild cognitive impairment (MCI). IR was estimated with the homeostasis model assessment of insulin resistance (HOMA‐IR). Cognitive performances were analyzed as a function of scores on the HOMA‐IR.ResultsThe group analysis those with and without IR did not show any differences in the cognitive performance although higher HOMA‐IR was closely associated with lower performances in immediate recall on the Seoul Verbal Learning Test (SVLT‐I) (r = −0.244, p = 0.026) and Controlled Oral Word Association Test (COWAT) (r = −0.270, p = 0.013). In subgroup analysis by APOE status, SVLT‐delayed (p = 0.027) and COWAT (p = 0.016) scores were found to be significantly lower in the IR than the non‐IR among those with APOE ε4 allele. In multiple regression analysis, impairment on the COWAT remained significantly correlated with scores on HOMA‐IR (β = −0.271, t = −2.340, p = 0.022). However, IR status was identified to interact with APOE ε4 carriership toward poor performances in the COWAT (β = −0.335, t = −2.285, p = 0.026).ConclusionThis study found a domain‐specific impact of HOMA‐IR scores on cognitive performances in non‐diabetic patients with MCI. This association was profound only in APOE ε4carriers. Copyright © 2014 John Wiley & Sons, Ltd.
Diisocyanates, occupational asthma and IgE antibody: implications for hazard characterization
Authors: Kimber Ian , Dearman Rebecca J. , Basketter David A. 
Published: July 2014

ABSTRACTSensitization of the respiratory tract by chemicals resulting in rhinitis and asthma is an important occupational health issue. Occupational asthma is associated with significant morbidity and can be fatal. Tests for the identification and characterization of chemicals with the potential to cause sensitization of the respiratory tract are lacking. In spite of sustained interest there are no validated or widely accepted methods available, and this presents toxicologists with a considerable challenge. One important constraint on the development of appropriate testing strategies has been uncertainty and controversy about the immunological mechanisms through which chemicals may induce sensitization of the respiratory tract. By analogy with protein respiratory allergy it is legitimate to consider that IgE antibody‐dependent mechanisms may play a pivotal role. However, although many aspects of chemical respiratory allergy are consistent with reactions caused by IgE antibody, uncertainty remains because among patients with occupational asthma caused by chemical respiratory allergens there are commonly a proportion, and sometimes a significant proportion, of subjects that lack detectable IgE antibody. Here we consider the relevance of IgE antibody responses for the development of a chemical respiratory allergy to diisocyanates. A case is made that IgE antibody responses are, either directly or indirectly, closely associated with occupational asthma to the diisocyanates (and to other chemical respiratory allergens). As such the argument is advanced here that IgE antibody represents an appropriate readout for the characterization of chemical respiratory allergens, and that uncertainty about mode of action should no longer represent a hurdle in the development of suitable test methods. Copyright © 2014 John Wiley & Sons, Ltd.
A Magnetically Separable Catalyst for Synthesis of 1‐Phenoxy‐2‐propanol Via Atom‐economic Reaction
Authors: Feng Shide , Cao Fengyun , Lu Bin , Cai Qinghai 
Published: July 2014

AbstractA magnetically separable catalyst Al2O3‐MgO/Fe3O4 was prepared by Al2O3‐MgO supported on magnetic oxide Fe3O4 and charactered by FT‐IR, XRD and SEM. The mixed oxides afforded high catalytic activity and selectivity for synthesis of 1‐phenoxy‐2‐propanol from phenol and propylene oxide with 80.3% conversion and 88.1% selectivity to 1‐phenoxy‐2‐propanol. Especially, facile separation of the catalyst by a magnet was obtained and the catalytic performance of the recovered catalyst was unaffected even at the forth run.
Recent Progress in Preparation and Lithium‐ion Storage Properties of TiO2 Mesocrystals
Authors: Hong Zhensheng , Wei Mingdeng 
Published: July 2014

AbstractTiO2 nanostructures have been considered as promising anode materials in a new generation of lithiumion batteries due to their high safety, superior rate capability and excellent cyclic stability. In particular, TiO2 mesocrystals, a new class of superstructured materials, have attracted a great deal of research interests due to the unique structure composed of crystallographically oriented nanocrystals, and thus showed improved lithium‐ion insertion performance. In this review, recent progress in preparation and lithium‐ion storage properties of TiO2 mesocrystals are summarized. Two typical ways for synthesizing TiO2 mesocrystals are described, namely, the oriented topotactic transformation and direct synthesis in solution. The additive‐free synthesis of TiO2 mesocrystals and their lithium‐ion intercalation properties are highlighted and discussed.