bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivariate Analysis: Overview
Authors: Krzanowski Wojtek J. 
Published: September 2014

Abstract
Multivariate analysis is appropriate whenever more than one variable is measured on each sample individual, and overall conclusions about the whole system are sought. Many different multivariate techniques now exist for addressing a variety of objectives. This brief review outlines, in broad terms, some of the more common objectives and sketches out some of the ways in which they are tackled. The techniques are grouped under four headings: visualization and description, extrapolation and inference, discrimination and classification, modeling and explanation. Within each heading, the chief objectives are first identified, and the rationales behind some of the specific techniques are sketched out. The review ends with an outline of current trends and recent developments.
Studying Microstructure in Molecular Crystals With Nanoindentation: Intergrowth Polymorphism in Felodipine
Authors: Mishra Manish Kumar , Desiraju Gautam R. , Ramamurty Upadrasta , Bond Andrew D. 
Published: September 2014

AbstractIntergrowth polymorphism refers to the existence of distinct structural domains within a single crystal of a compound. The phenomenon is exhibited by form II of the active pharmaceutical ingredient felodipine, and the associated microstructure is a significant feature of the compound’s structural identity. Employing the technique of nanoindentation on form II reveals a bimodal mechanical response on specific single‐crystal faces, demonstrating distinct properties for two polymorphic forms within the same crystal.
Fluorocarbon and Hydrocarbon N‐Heterocyclic (C5–C7) Imidazole‐Based Liquid Crystals
Authors: Chen Hongren , Hong Fengying , Shao Guang , Hang Deyu , Zhao Lei , Zeng Zhuo 
Published: September 2014

AbstractBy using three synthetic protocols, a series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals (LCs) and related imidazolium‐based ionic liquid crystals (ILCs) have been prepared. The ring size of the N‐heterocycle and the length of the N‐terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid‐crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole‐based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based LCs and related imidazolium‐based ILCs could be used as new liquid‐crystalline materials.
Synthesis and Photophysical Behavior of a Supramolecular Nanowire made from Dithienylethene‐Bridged Bis(permethyl‐β‐cyclodextrin)s and Porphyrins
Authors: Yang Yang , Zhang Ying‐Ming , Zhang Yue , Xu Xiufang , Liu Yu 
Published: September 2014

AbstractA photochromic dithienylethene‐bridged bis(permethyl‐β‐cyclodextrin)s was successfully synthesized through an amide condensation reaction, and its photochromic properties were also investigated by 1H NMR spectra and UV/vis spectroscopy. Moreover, taking advantage of the strong interaction between permethyl‐β‐cyclodextrin and water soluble porphyrins, a supramolecular nanowire was then successfully constructed and characterized by UV/vis spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Significantly, the fluorescence resonance energy transfer (FRET) process from the porphyrin to the dithienylethene core can be modulated by alternate irradiation with ultraviolet and visible light and, thus, light‐controlled quenching and recovery of fluorescence of porphyrins was realized.
Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N‐Heterocyclic Carbenes with Palladium(II)
Authors: Yu Kuo‐Hsuan , Wang Chia‐Ching , Chang I‐Hsin , Liu Yi‐Hung , Wang Yu , Elsevier Cornelis J. , Liu Shiuh‐Tzung , Chen Jwu‐Ting 
Published: September 2014

AbstractImidazolium salts, [RS(O)CH2(C3H3N2)Mes]Cl (R=Me (L1 a), Ph (L1 b)); Mes=mesityl), make convenient carbene precursors. Palladation of L1 a affords the monodentate dinuclear complex, [(PdCl2{MeS(O)CH2(C3H2N2)Mes})2] (2 a), which is converted into trans‐[PdCl2(NHC)2] (trans‐4 a; N‐heterocyclic carbene) with two rotamers in anti and syn configurations. Complex trans‐4 a can isomerize into cis‐4 a(anti) at reflux in acetonitrile. Abstraction of chlorides from 4 a or 4 b leads to the formation of a new dication: trans‐[Pd{RS(O)CH2(C3H2N2)Mes}2](PF6)2 (R=Me (5 a), Ph (5 b)). The X‐ray structure of 5 a provides evidence that the two bidentate SONHC ligands at palladium(II) are in square‐planar geometry. Two sulfoxides are sulfur‐ and oxygen‐bound, and constitute five‐ and six‐membered chelate rings with the metal center, respectively. In acetonitrile, complexes 5 a or 5 b spontaneously transform into cis‐[Pd(NHC)2(NCMe)2](PF6)2. Similar studies of thioether–NHCs have also been examined for comparison. The results indicate that sulfoxides are more labile than thioethers.
Highly Selective and Sensitive Near‐Infrared‐Fluorescent Probes for the Detection of Cellular Hydrogen Sulfide and the Imaging of H2S in Mice
Authors: Wu Haixia , Krishnakumar Saarangan , Yu Jie , Liang Dong , Qi Hongyi , Lee Zheng‐Wei , Deng Lih‐Wen , Huang Dejian 
Published: September 2014

AbstractHerein, we report the development of two fluorescent probes for the highly selective and sensitive detection of H2S. The probes take advantage of a CuIIcyclen complex, which acts as a reaction center for H2S and as a quencher of BODIPY (boron‐dipyrromethene)‐based fluorophores with emissions at 765 and 680 nm, respectively. These non‐fluorescent probes could only be turned on by the addition of H2S, and not by other potentially interfering biomolecules, including reactive oxygen species, cysteine, and glutathione. In a chemical system, both probes detected H2S with a detection limit of 80 nM. The probes were successfully used for the endogenous detection of H2S in HEK 293 cells, for measuring the H2S‐release activity of dietary organosulfides in MCF‐7 cells, and for the in vivo imaging of H2S in mice.
A Cyclic KLVFF‐Derived Peptide Aggregation Inhibitor Induces the Formation of Less‐Toxic Off‐Pathway Amyloid‐β Oligomers
Authors: Arai Tadamasa , Sasaki Daisuke , Araya Takushi , Sato Takeshi , Sohma Youhei , Kanai Motomu 
Published: September 2014

AbstractInhibition of amyloid‐β (Aβ) aggregation could be a target of drug development for the treatment of currently incurable Alzheimer's disease. We previously reported that a head‐to‐tail cyclic peptide of KLVFF (cyclic‐KLVFF), a pentapeptide fragment corresponding to the Aβ16–20 region (which plays a critical role in the generating Aβ fibrils), possesses potent inhibitory activity against Aβ aggregation. Here we found that the inhibitory activity of cyclic‐KLVFF was significantly improved by incorporating an additional phenyl group at the β‐position of the Phe4 side chain (inhibitor 3). Biophysical and biochemical analyses revealed the rapid formation of 3‐embedded oligomer species when Aβ1–42 was mixed with 3. The oligomer species is an “off‐pathway” species with low affinity for cross‐β‐sheet‐specific dye thioflavin T and oligomer‐specific A11 antibodies. The oligomer species had a sub‐nanometer height and little capability of aggregation to amyloid fibrils. Importantly, the toxicity of the oligomer species was significantly lower than that of native Aβ oligomers. These insights will be useful for further refinement of cyclic‐KLVFF‐based aggregation inhibitors.
Outcomes using a clinical practice pathway for the management of pulse loss following pediatric cardiac catheterization
Authors: Glatz Andrew C. , Keashen Rachel , Chang Julie , Balsama Lisa‐Ann , Dori Yoav , Gillespie Matthew J. , Giglia Therese M. , Raffini Leslie , Rome Jonathan J. 
Published: September 2014

ObjectiveObjectives To describe the results of a clinical practice pathway (CPP) for the management of postcatheterization pulse loss in a children's hospital.BackgroundStandardized approaches to the diagnosis and management of postcatheterization arterial thrombus are lacking. As a result, substantial practice variation exists.MethodsData collected prospectively for quality improvement purposes were retrospectively reviewed.ResultsSince initiation of the CPP, 93/1,672 (5.4%) catheterizations resulted in pulse loss at a median patient age and weight of 73 days (1 day–5.8 years) and 4.8 kg (2–14.1 kg). Arterial thrombus was documented by ultrasound (US) in 85. Of these, 66 resolved by 12 weeks of therapy, seven patients died, and four were lost to follow‐up before completing treatment. Eight patients had persistent thrombus despite a full treatment course (89% success rate in those able to complete treatment). Of patients treated with unfractionated heparin as initial therapy, 46% (17/37) achieved a therapeutic partial thromboplastin time within 12 hr with 19% (67/343) of all levels therapeutic. As a result, the CPP was modified to use enoxaparin as first line agent, of which 57% (41/72) had a therapeutic anti‐Xa level after the 2nd dose and 88% by the 4th dose. No bleeding complications were observed. A priori established process metrics were achieved.ConclusionsA CPP utilizing early initiation of anticoagulation and US to aid diagnosis of postcatheterization arterial thrombus and response to therapy is feasible and effective. In those able to complete up to 12 weeks of treatment, resolution occurs in nearly 90%. © 2014 Wiley Periodicals, Inc.
Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides Catalyzed by a Keggin‐Type Polyoxometalate‐Supported Rhenium Carbonyl Derivate in Ionic Liquid
Authors: Huo Zhiyuan , Zhao Juan , Bu Zhanwei , Ma Pengtao , Liu Qisen , Niu Jingyang , Wang Jingping 
Published: September 2014

AbstractA monovacant Keggin‐type polyoxometalate‐supported trirhenium carbonyl derivate [(CH3)4N]5H23[(PW11O39){Re(CO)3}3(μ3‐O)(μ2‐OH)]4⋅24 H2O was synthesized. It was used as a catalyst for the synthesis of cyclic carbonates from carbon dioxide and epoxides under mild reaction conditions with co‐catalyst pyrrolidinium bromide. The catalyst system was recycled 10 times with only a small decline in yield. The catalytic mechanism was hypothesized based on experimental results and the frontier orbitals computed by DFT calculations.
Heterogeneously Catalyzed Hydrogenation of Squalene to Squalane under Mild Conditions
Authors: Pandarus Valerica , Ciriminna Rosaria , Kaliaguine Serge , Béland François , Pagliaro Mario 
Published: September 2014

AbstractThe full chemoselective hydrogenation of highly unsaturated all‐trans linear squalene into valuable fully saturated squalane is achieved smoothly under mild conditions over the sol–gel‐entrapped Pd catalyst SiliaCat Pd0. The catalysis is truly heterogeneous, and the catalyst is stable and recyclable, which opens the route to an easier and less expensive hydrogenation of squalene.
Development of Electrolytes towards Achieving Safe and High‐Performance Energy‐Storage Devices: A Review
Authors: Wang Yu , Zhong Wei‐Hong 
Published: September 2014

AbstractIncreasing interest in flexible/wearable electronics, clean energy, electrical vehicles, and so forth is calling for advanced energy‐storage devices, such as high‐performance lithium‐ion batteries (LIBs), which can not only store energy efficiently and safely, but also possess additional properties, such as good mechanical properties to bear deformations or even to be used as structural components. These expectations first indicate the directions, but also raise new challenges for the advancement of energy materials. As one of the critical components in LIBs, the electrolyte connecting the two electrodes is vital for achieving the desired performances in batteries. In this Review, the developments of various liquid electrolytes (organic, ionic liquid, and aqueous electrolytes), solid electrolytes (solid polymer and inorganic solid), as well as gel electrolytes is briefly summarized and discussed. For each type of electrolyte, the challenging issues and possible solutions are discussed. In particular, safety, ionic conductivity, and contact/interface issues are emphasized. Finally, from a composite point of view, strategies for the development of high‐performance electrolytes with all‐round properties are proposed.
Synthesis of {100} Facet Dominant Anatase TiO2 Nanobelts and the Origin of Facet‐Dependent Photoreactivity
Authors: Pan Feng , Wu Kai , Li Hexing , Xu Guoqin , Chen Wei 
Published: September 2014

AbstractSword‐like anatase TiO2 nanobelts exposed with 78 % clean {100} facets were synthesized and the facet‐dependent photoreactivity of anatase TiO2 was investigated. By quantitative comparison with the reference {001} facets, the {100} facets possessed about ten‐times higher active sites density than that on {001} facets, resulting in higher photoreaction efficiency. After the active sites density normalization, the {100} and {001} facets exhibited distinct wavelength‐dependent photocatalytic performance, attributed to the anisotropic electronic structures in TiO2 crystals.
Stereoselective Total Synthesis and Structural Elucidation of (−)‐Indoxamycins A–F
Authors: He Chi , Zhu Chenlong , Wang Bingnan , Ding Hanfeng 
Published: September 2014

AbstractIn this study, a concise and stereoselective approach for the divergent total synthesis of (−)‐indoxamycins A–F is described. The key steps of the strategy include an Ireland–Claisen rearrangement, an enantioselective 1,6‐enyne reductive cyclization, and a tandem 1,2‐addition/oxa‐Michael/methylenation reaction. The relative and absolute configuration of these natural products has been unambiguously elucidated, and their cytotoxic activities against HT‐29 and A‐549 tumor cell lines are also reported.
Dramatic Influence of an Anionic Donor on the Oxygen‐Atom Transfer Reactivity of a MnV–Oxo Complex
Authors: Neu Heather M. , Quesne Matthew G. , Yang Tzuhsiung , Prokop‐Prigge Katharine A. , Lancaster Kyle M. , Donohoe James , DeBeer Serena , de Visser Sam P. , Goldberg David P. 
Published: September 2014

AbstractAddition of an anionic donor to an MnV(O) porphyrinoid complex causes a dramatic increase in 2‐electron oxygen‐atom‐transfer (OAT) chemistry. The 6‐coordinate [MnV(O)(TBP8Cz)(CN)]− was generated from addition of Bu4N+CN− to the 5‐coordinate MnV(O) precursor. The cyanide‐ligated complex was characterized for the first time by Mn K‐edge X‐ray absorption spectroscopy (XAS) and gives MnO=1.53 Å, MnCN=2.21 Å. In combination with computational studies these distances were shown to correlate with a singlet ground state. Reaction of the CN− complex with thioethers results in OAT to give the corresponding sulfoxide and a 2e−‐reduced MnIII(CN)− complex. Kinetic measurements reveal a dramatic rate enhancement for OAT of approximately 24 000‐fold versus the same reaction for the parent 5‐coordinate complex. An Eyring analysis gives ΔH≠=14 kcal mol−1, ΔS≠=−10 cal mol−1 K−1. Computational studies fully support the structures, spin states, and relative reactivity of the 5‐ and 6‐coordinate MnV(O) complexes.
Unexpected Anion Effect in the Alkoxylation of Alkynes Catalyzed by N‐Heterocyclic Carbene (NHC) Cationic Gold Complexes
Authors: Biasiolo Luca , Trinchillo Marina , Belanzoni Paola , Belpassi Leonardo , Busico Vincenzo , Ciancaleoni Gianluca , D'Amora Angela , Macchioni Alceo , Tarantelli Francesco , Zuccaccia Daniele 
Published: September 2014

AbstractThe intermolecular alkoxylation of alkynes is the oldest application of cationic gold(I) catalysts; however, no systematic experimental data about the role of the anion are available. In this contribution, the role of the anion in this catalytic reaction as promoted by a N‐heterocyclic carbene‐based gold catalyst, [(NHC)AuX] (X=BARF−, BF4−, OTf−, OTs−, TFA−, or OAc−) is analyzed, through a combined experimental (NMR spectroscopy) and theoretical (DFT calculation) approach. The most important factor seems to be the ability to abstract the proton from the methanol during the nucleophilic attack, and such ability is related to the anion basicity. On the other hand, too high coordination power or basicity of the anion worsens the catalytic performance by preventing alkyne coordination or by forming too much free methoxide in solution, which poisons the catalyst. The intermediate coordinating power and basicity of the OTs− anion provides the best compromise to achieve efficient catalysis.
Numerical analysis of solutal Marangoni convections in porous media
Authors: Alizadeh Mostafa , Rostami Behzad , Khosravi Maryam 
Published: September 2014

AbstractThe possibility of instability initiation in porous media by Marangoni convection is studied numerically with a special focus on its application in petroleum engineering and enhanced oil recovery (EOR). Both types of micro‐ and macro‐convections are considered. The finite element method is employed to solve the models numerically. The appropriate Marangoni numbers are introduced according to the model after making equations and boundary conditions dimensionless. In order to evaluate micro‐convections in porous media, the Molenkamp model is extended and validation is performed by comparing concentration maps in a special case. For macro‐convections, a specific concentration distribution is imposed on the boundary to simulate similar conditions in EOR. Results showed that micro‐convections are not strong enough to alter the fluid flow in porous media in applicable ranges of Marangoni numbers and porous media properties. On the other hand, for macro‐convection results, fourteen test cases, each with three different porosities, are defined. As a result, the margin of stability is found and it is also shown that the damping forces of porous media delays the onset of convection.
A massive data processing approach for effective trustworthiness in online learning groups
Authors: Miguel Jorge , Caballé Santi , Xhafa Fatos , Prieto Josep 
Published: September 2014

SummaryThis paper proposes a trustworthiness‐based approach for the design of secure learning activities in online learning groups. Although computer‐supported collaborative learning has been widely adopted in many educational institutions over the last decade, there exist still drawbacks that limit its potential. Among these limitations, we investigate on information security vulnerabilities in learning activities, which may be developed in online collaborative learning contexts. Although security advanced methodologies and technologies are deployed in learning management systems, many security vulnerabilities are still not satisfactorily solved. To overcome these deficiencies, we first propose the guidelines of a holistic security model in online collaborative learning through an effective trustworthiness approach. However, as learners' trustworthiness analysis involves large amount of data generated along learning activities, processing this information is computationally costly, especially if required in real time. As the main contribution of this paper, we eventually propose a parallel processing approach, which can considerably decrease the time of data processing, thus allowing for building relevant trustworthiness models to support learning activities even in real time. Copyright © 2014 John Wiley & Sons, Ltd.
Laser Sculpting of Atomic sp, sp2, and sp3 Hybrid Orbitals
Authors: Liu Chunmei , Manz Jörn , Yang Yonggang 
Published: September 2014

AbstractAtomic sp, sp2, and sp3 hybrid orbitals were introduced by Linus Pauling to explain the nature of the chemical bond. Quantum dynamics simulations show that they can be sculpted by means of a selective series of coherent laser pulses, starting from the 1s orbital of the hydrogen atom. Laser hybridization generates atoms with state‐selective electric dipoles, opening up new possibilities for the study of chemical reaction dynamics and heterogeneous catalysis.
A Fluorescence Switch for the Detection of Nitric Oxide and Histidine and Its Application in Live Cell Imaging
Authors: Sivaraman Gandhi , Anand Thangaraj , Chellappa Duraisamy 
Published: September 2014

AbstractA rhodamine‐based copper complex as a selective, sensitive turn‐on fluorescent chemosensor for NO/histidine has been developed. A conspicuous fluorescence enhancement was observed in the presence of nitric oxide/histidine. The probe was specific towards NO over other reactive oxygen species and reactive nitrogen species. The probe showed selective fluorescence enhancement with histidine; the other naturally occurring amino acids did not result in fluorescence enhancement. EPR and ESIMS studies clearly showed that NO‐induced reduction of copper ions leads to the fluorescence enhancement. The viability of the probe for fluorescent imaging of nitric oxide and histidine in living cells has been demonstrated by means of confocal laser scanning microscopy experiments.
Synthesis, Characterization, and Interconversion of β‐Diketiminato Nickel NxHy Complexes
Authors: Köthe Claudia , Braun Beatrice , Herwig Christian , Limberg Christian 
Published: September 2014

AbstractThe β‐diketiminato nickel(II) hydrazido(–1) complex [LtBuNi(η2‐N2H3)], (IV) was investigated with respect to its deprotonation/protonation behavior. Deprotonation with KOtBu led to [LtBuNi(μ,η2:η2‐N2H2)K(solv)] (1), and this process was proven to be reversible. Spectroscopic and DFT studies revealed an electronic structure intermediate between nickel(II) hydrazido(–2) and nickel(0) diazene. On the other hand, protonation of IV with [LutH]OTf reversibly generated the hydrazine complex [LtBuNi(η2‐N2H4)]OTf (2). Warming a solution of IV led to N–N bond cleavage yielding the nickel(I) ammine complex [LtBuNi(NH3)], (3). Hence, LtBuNi moieties were shown to effectively activate NxHy species for diverse conversions.
The activation of spinal astrocytes contributes to preoperative anxiety‐induced persistent post‐operative pain in a rat model of incisional pain
Authors: Liu Y. , Hou B. , Zhang W. , Sun Y.‐E. , Li L. , Ma Z. , Gu X. 
Published: September 2014

AbstractBackgroundPreoperative anxiety, a clinically significant problem for many patients undergoing surgery, is associated with prolonged and exacerbated post‐operative pain. To date, the mechanisms of preoperative anxiety‐induced persistent post‐operative pain remain unclear. The present study aimed to provide a rat model of preoperative anxiety‐induced persistent post‐operative pain using the single‐prolonged stress (SPS) procedure to induce preoperative anxiety‐like behaviours, and to explore the role of spinal astrocytes in this phenomenon.MethodsRats were exposed to the SPS procedure to induce preoperative anxiety‐like behaviours. Subsequently, acute post‐operative pain was developed using a 1‐cm longitudinal incision through skin and fascia of the plantar aspect of the right hindpaw. Mechanical allodynia was measured before and after the incision. Immunofluorescence assay was used to assess the expression of glial fibrillary acidic protein and the activation of astrocytes in spinal dorsal horn.ResultsThe SPS performed before the incision resulted in (1) enhanced preoperative anxiety‐like behaviours as revealed by the elevated plus maze tests; (2) exacerbated and prolonged mechanical allodynia that lasted for at least 28 post‐operative days; and (3) activation of astrocytes in the lumbar spinal dorsal horn.ConclusionsThe data suggest that this rat model, which could mimic the clinical persistent post‐operative pain induced by preoperative anxiety, may be a useful tool to explore the mechanisms as well as effective prevention and treatment for this problem. Furthermore, spinal astrocytes activation may contribute to the development of post‐operative hyperalgesia in this model.