bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of acute responsive high frequency stimulation of the subiculum on the intra‐hippocampal kainic acid seizure model in rats
Authors: Huang L. , van Luijtelaar G. 
Published: July 2012

AbstractThe effects of acute responsive high frequency stimulation (HFS) to the subiculum on seizures and interictal spikes were investigated in a semi‐acute kainic acid (KA) induced seizure model in rats. Wistar rats (n = 15) were implanted with an electrode‐cannula complex in the CA3 area, stimulation and recording electrodes in the subiculum and another recording electrode at the contralateral motor cortex. Two weeks later rats were injected repeatedly with KA (0.05 μg/0.1 μL) for 3 days with an interval of 48 h. HFS (125 Hz, 100 μsec) was delivered to the subiculum at a predetermined intensity range (100–500 μA) in the HFS group (n = 7) when seizures were visually detected, while no stimulation was delivered in the sham control group (n = 8). Various severities of seizures were obtained (Stage I–V) and all rats of both groups reached Stage V (Racine's scale) on Day 1. The HFS group had less focal seizures and a longer inter‐focal seizure interval on Day 1. Interictal spike rate was also lower in the HFS group and decreased with injection days. Significant day effects were found for the latency, number of focal seizures, and duration of focal seizures and generalized seizures while differences between groups were no longer present. Responsive HFS did not disrupt ongoing seizures. However, focal seizures and interictal spikes were suppressed by HFS. Such anticonvulsant effects of acute subicular stimulation indicate that the subiculum is involved in seizure generation. The reduction of seizure sensitivity over the injection day reflects an intrinsic anticonvulsant mechanism.
Characterization of recovered walking patterns and motor control after contusive spinal cord injury in rats
Authors: Hansen Christopher N. , Linklater William , Santiago Raquel , Fisher Lesley C. , Moran Stephanie , Buford John A. , Michele Basso D. 
Published: July 2012

AbstractCurrently, complete recovery is unattainable for most individuals with spinal cord injury (SCI). Instead, recovery is typically accompanied by persistent sensory and motor deficits. Restoration of preinjury function will likely depend on improving plasticity and integration of these impaired systems. Eccentric muscle actions require precise integration of sensorimotor signals and are predominant during the yield (E2) phase of locomotion. Motor neuron activation and control during eccentric contractions is impaired across a number of central nervous system (CNS) disorders, but remains unexamined after SCI. Therefore, we characterized locomotor recovery after contusive SCI using hindlimb (HL) kinematics and electromyographic (EMG) recordings with specific consideration of eccentric phases of treadmill (TM) walking. Deficits in E2 and a caudal shift of locomotor subphases persisted throughout the 3‐week recovery period. EMG records showed notable deficits in the semitendinosus (ST) during yield. Unlike other HL muscles, recruitment of ST changed with recovery. At 7 days, the typical dual‐burst pattern of ST was lost and the second burst (ST2) was indistinct. By 21 days, the dual‐burst pattern returned, but latencies remained impaired. We show that ST2 burst duration is highly predictive of open field Basso, Beattie, Bresnahan (BBB) scores. Moreover, we found that simple changes in locomotor specificity which enhance eccentric actions result in new motor patterns after SCI. Our findings identify a caudal shift in stepping kinematics, irregularities in E2, and aberrant ST2 bursting as markers of incomplete recovery. These residual impairments may provide opportunities for targeted rehabilitation.
The transformative potential of marketing from the consumers' point of view
Authors: Heath Teresa Pereira , Chatzidakis Andreas 
Published: July 2012

ABSTRACTIn this article, we explore consumers' perceptions of marketing and the extent to which they believe that marketing can play a positive transformative role in society. Findings from 36 semistructured interviews indicate that consumers typically perceive marketing as having a traditional short‐term, transactional, and ‘company‐focused’ orientation rather than a transformative one. This was reflected in participants' views of marketing, as well as in their choices and comments when they were given two academic definitions of marketing and one description of unethical marketing and asked to choose the one they thought best described marketing. In addition, participants viewed marketing as manipulative, and most held one‐sidedly negative opinions of its transformative potential. The majority did not feel autonomous in their purchase decisions, calling into question marketers' usual defence that consumers are sovereign. In a similar vein, they expressed concerns about the effects of marketing's manipulative and deceptive techniques on vulnerable consumers. These findings are rather worrying given that enhancing the transformative potential of marketing requires a more nuanced understanding of its role and function within society. Accordingly, we argue that successful transformative marketing interventions need to take into account and address consumers' disbelief as to the capacity of marketing to improve social welfare. Copyright © 2012 John Wiley & Sons, Ltd.
Taste lovers versus nutrition fact seekers: How health consciousness and self‐efficacy determine the way consumers choose food products
Authors: Mai Robert , Hoffmann Stefan 
Published: July 2012

ABSTRACTThis article identifies consumer segments that differ in the way they consider health‐related and health‐unrelated food properties when making food choices. The paper makes two assumptions: first, the level of health consciousness determines the quality of the attributes (health related versus health unrelated) these segments consider important; and second, the degree of nutrition‐related self‐efficacy subsequently defines the quantity of health‐related attributes considered important. Two studies measure preferences for food attributes (Study 1: n = 54, 12 attributes, conjoint analysis; Study 2: n = 162, 25 attributes, constant sum scales). In both studies, cluster analysis identifies two major segments (taste lovers and nutrition fact seekers) that are determined by consumers' level of health consciousness. Study 2 demonstrates that nutrition‐related self‐efficacy determines how many health‐related attributes nutrition fact seekers consider important. Consequently, they can be split into ‘heavy’ and ‘soft’ subsegments. The study also identifies a segment that lacks a clear food choice strategy as a result of incompatible beliefs. The paper guides marketers and producers in developing healthy food products tailored to the needs of different target segments. Considering the enormous health expenditures, the studies' results are also beneficial to policy makers and governmental organizations to design social marketing campaigns. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis and Structural Characterization of New Divanada‐ and Diniobaboranes Containing Chalcogen Atoms
Authors: Roy Dipak Kumar , Bose Shubhankar Kumar , Geetharani K. , Varma Chakrahari Kiran Kumar , Mobin Shaikh M. , Ghosh Sundargopal 
Published: July 2012

AbstractThe reaction of [CpnMCl4−x] (M=V: n=2, x=2; M=Nb: n=1, x=0; Cp=η5‐C5H5) with LiBH4⋅THF followed by thermolysis in the presence of dichalcogenide ligands E2R2 (E=S, Te; R=2,6‐(tBu)2‐C6H2OH, Ph) and 2‐mercaptobenzothiazole (C7H5NS2) yielded dimetallaheteroboranes [{CpV(μ‐TePh)}2(μ3‐Te)BH⋅thf] (1), [(CpV)2(BH3S)2] (2), [(CpNb)2B4H10S] (3), [(CpNb)2B4H11S(tBu)2C6H2OH] (4), and [(CpNb)2B4H11TePh] (5). In cluster 1, the V2BTe atoms define a tetrahedral framework in which the boron atom is linked to a THF molecule. Compound 2 can be described as a dimetallathiaborane that is built from two edge‐fused V2BS tetrahedron clusters. Cluster 3 can be considered as an edge‐fused cluster in which a trigonal‐bipyramidal unit (Nb2B2S) has been fused with a tetrahedral core (Nb2B2) by means of a common Nb2 edge. In addition, thermolysis of an in‐situ‐generated intermediate that was produced from the reaction of [Cp2VCl2] and LiBH4⋅THF with excess BH3⋅THF yielded oxavanadaborane [(CpV)2B3H8(μ3‐OEt)] (6) and divanadaborane cluster [(CpV)2B5H11] (7). Cluster 7 exhibits a nido geometry with C2v symmetry and it is isostructural with [(Cp*M)2B5H9+n] (M=Cr, Mo, and W, n=0; M=Ta, n=2; Cp*=η5‐C5Me5). All of these new compounds have been characterized by 1H NMR, 11B NMR, and 13C NMR spectroscopy and elemental analysis and the structural types were established unequivocally by crystallographic analysis of compounds 1–4, 6, and 7.
Supramolecular Binding Thermodynamics by Dispersion‐Corrected Density Functional Theory
Authors: Grimme Stefan 
Published: July 2012

AbstractThe equilibrium association free enthalpies ΔGa for typical supramolecular complexes in solution are calculated by ab initio quantum chemical methods. Ten neutral and three positively charged complexes with experimental ΔGa values in the range 0 to −21 kcal mol−1 (on average −6 kcal mol−1) are investigated. The theoretical approach employs a (nondynamic) single‐structure model, but computes the various energy terms accurately without any special empirical adjustments. Dispersion corrected density functional theory (DFT‐D3) with extended basis sets (triple‐ζ and quadruple‐ζ quality) is used to determine structures and gas‐phase interaction energies (ΔE), the COSMO‐RS continuum solvation model (based on DFT data) provides solvation free enthalpies and the remaining ro‐vibrational enthalpic/entropic contributions are obtained from harmonic frequency calculations. Low‐lying vibrational modes are treated by a free‐rotor approximation. The accurate account of London dispersion interactions is mandatory with contributions in the range −5 to −60 kcal mol−1 (up to 200 % of ΔE). Inclusion of three‐body dispersion effects improves the results considerably. A semilocal (TPSS) and a hybrid density functional (PW6B95) have been tested. Although the ΔGa values result as a sum of individually large terms with opposite sign (ΔE vs. solvation and entropy change), the approach provides unprecedented accuracy for ΔGa values with errors of only 2 kcal mol−1 on average. Relative affinities for different guests inside the same host are always obtained correctly. The procedure is suggested as a predictive tool in supramolecular chemistry and can be applied routinely to semirigid systems with 300–400 atoms. The various contributions to binding and enthalpy–entropy compensations are discussed.
Dramatic Substituent Effects on the Photoluminescence of Boron Complexes of 2‐(Benzothiazol‐2‐yl)phenols
Authors: Santra Mithun , Moon Hyunsoo , Park Min‐Ho , Lee Tae‐Woo , Kim Young Kook , Ahn Kyo Han 
Published: July 2012

AbstractSubstituents can induce dramatic changes in the photoluminescence properties of N,O‐chelated boron complexes. Specifically, the boron complexes of 2‐(benzothiazol‐2‐yl)phenols become bright deep blue‐ and orange‐red‐emitting materials depending on amino substituents at the 5‐ and 4‐positions of 2‐(benzothiazol‐2‐yl)phenol, respectively. Absorption and emission data show that the resulting boron complexes have little or small overlap between the absorption and emission spectra and, furthermore, X‐ray crystal structures for both the blue and orange‐red complexes indicate the absence of π–π stacking interaction in the crystal‐packing structures. These features endow the boron complexes with bright and strong photoluminescence in the solid state, which distinguishes itself from the typical boron complexes of dipyrromethenes (BODIPYs). A preliminary study indicates that the blue complexes have promising electro‐optical characteristics as dopant in an organic light‐emitting diode (OLED) device and show chromaticity close to an ideal deep blue. The substituent effects on the photoluminescent properties may be used to tune the desired emission wavelength of related boron or other metal complexes.
Symmetry‐Enthalpy Correlations in Diels–Alder Reactions
Authors: Tuvi‐Arad Inbal , Avnir David 
Published: July 2012

AbstractWoodward–Hoffmann (WH) rules provide strict symmetry selection rules: when they are obeyed, a reaction proceeds; when they are not obeyed, there is no reaction. However, the voluminous experimental literature provides ample evidence that strict compliance to symmetry requirements is not an obstacle for a concerted reaction to proceed, and therefore the idea has developed that it is enough to have a certain degree of the required symmetry to have reactivity. Here we provide quantitative evidence of that link, and show that as one deviates from the desired symmetry, the enthalpy of activation increases, that is, we show that concerted reactions slow down the further they are from the ideal symmetry. Specifically, we study the deviation from mirror symmetry (evaluated with the continuous symmetry measure (CSM)) of the [4+2] carbon skeleton of the transition state of a series of twelve Diels–Alder reactions in seven different solvents (and in the gas phase), in which the dienes are butadiene, cyclopentadiene, cyclohexadiene, and cycloheptadiene; the dienophiles are the 1‐, 1,1‐, and 1,1,2‐cyanoethylene derivatives; the solvents were chosen to sample a range of dielectric constants from heptane to ethanol. These components provide twenty‐four symmetry–enthalpy DFT‐calculated correlation lines (out of which only one case is a relatively mild exception) that show the general trend of increase in enthalpy as symmetry decreases. The various combinations between the dienophiles, cyanoethylenes, and solvents provide all kinds of sources for symmetry deviations; it is therefore remarkable that although the enthalpy of activation is dictated by various parameters, symmetry emerges as a primary parameter. In our analysis we also bisected this overall picture into solvent effects and geometry variation effects to evaluate under which conditions the electronic effects are more dominant than symmetry effects.
The Structural Diversity Triggered by Intermolecular Interactions between AuIS2 Groups: Aurophilia and Beyond
Authors: Azani Mohammad‐Reza , Castillo Oscar , Gallego M. Luz , Parella Teodor , Aullón Gabriel , Crespo Olga , Laguna Antonio , Alvarez Santiago , Mas‐Ballesté Rubén , Zamora Félix 
Published: July 2012

AbstractThe present study is aimed at elucidating the factors that direct the assembly of a specific family of AuI species. The assembly of AuI centers and dithiocarboxylato or xanthato ligands results in a surprising structural diversity observed by single‐crystal X‐ray diffraction. However, in solution, just evidences for discrete bimetallic [Au2L2] species have been observed. Interestingly, when dithiocarboxylato ligands have been used, a reversible supramolecular assembly has been observed forming the supramolecules of formulae [Au2L2]2 and [Au2L2]3. Initial studies on luminescent properties have been carried out at variable temperature. All the compounds show red emissions in the solid state at very similar energies, suggesting that the intramolecular interactions play a more relevant role in the luminescent properties than the intermolecular ones. The computational studies indicate that not only Au⋅⋅⋅Au interactions, but also Au⋅⋅⋅S and S⋅⋅⋅S ones play a role in the structure and energetic of the supramolecular species, as well as for the choice between supramolecular association or intramolecular oligomerization.
Hydrogen‐Bonding Induced Alternate Stacking of Donor (D) and Acceptor (A) Chromophores and their Supramolecular Switching to Segregated States
Authors: Das Anindita , Molla Mijanur Rahaman , Maity Bholanath , Koley Debasis , Ghosh Suhrit 
Published: July 2012

AbstractThis paper reports comprehensive studies on the mixed assembly of bis‐(trialkoxybenzamide)‐functionalized dialkoxynaphthalene (DAN) donors and naphthalene‐diimide (NDI) acceptors due the cooperative effects of hydrogen bonding, charge‐transfer (CT) interactions, and solvophobic effects. A series of DAN as well as NDI building blocks have been examined (wherein the relative distance between the two amide groups in a particular chromophore is the variable structural parameter) to understand the structure‐dependent variation in mode of supramolecular assembly and morphology (organogel, reverse vesicle, etc.) of the self‐assembled material. Interestingly, it was observed that when the amide functionalities are introduced to enhance the self‐assembly propensity, the mode of co‐assembly among the DAN and NDI chromophores no longer remained trivial and was dictated by a relatively stronger hydrogen‐bonding interaction instead of a weak CT interaction. Consequently, in a highly non‐polar solvent like methylcyclohexane (MCH), although kinetically controlled CT‐gelation was initially noticed, within a few hours the system sacrificed the CT‐interaction and switched over to the more stable self‐sorted gel to maximize the gain in enthalpy from the hydrogen‐bonding interaction. In contrast, in a relatively less non‐polar solvent such as tetrachloroethylene (TCE), in which the strength of hydrogen bonding is inherently weak, the contribution of the CT interaction also had to be accounted for along with hydrogen bonding leading to a stable CT‐state in the gel or solution phase. The stability and morphology of the CT complex and rate of supramolecular switching (from CT to segregated state) were found to be greatly influenced by subtle structural variation of the building blocks, solvent polarity, and the DAN/NDI ratio. For example, in a given D–A pair, by introducing just one methylene unit in the spacer segment of either of the building blocks a complete change in the mode of co‐assembly (CT state or segregated state) and the morphology (1D fiber to 2D reverse vesicle) was observed. The role of solvent polarity, structural variation, and D/A ratio on the nature of co‐assembly, morphology, and the unprecedented supramolecular‐switching phenomenon have been studied by detail spectroscopic and microscopic experiments in a gel as well as in the solution state and are well supported by DFT calculations.
Activation and Coordination of Ammonia at [Cp*Ir(H)2]: NMR and Matrix Isolation Studies
Authors: Jungton Ann‐Katrin , Herwig Christian , Braun Thomas , Limberg Christian 
Published: July 2012

Abstract1H NMR exchange spectroscopy of a reaction mixture of [Cp*Ir(H)4] (1; Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) and ammonia suggests an exchange of hydrogen atoms between the hydrido ligands and ammonia. Treatment of 1 with ND3 led to an H/D exchange between ND3 and the hydrido ligands of 1. Subsequent studies showed that photolysis of 1 isolated in frozen argon matrices leads to the formation of the iridium compounds [Cp*Ir(H)2] (2) and [Cp*Ir(H)3] (4), as it was confirmed by IR spectroscopy. In the presence of water the aqua complex [Cp*Ir(H)2(OH2)] (3) was generated simultaneously. Accordingly, photolysis of 1 in an argon matrix doped with ammonia gave rise to the ammine complex [Cp*Ir(H)2(NH3)] (5). IR assignments were supported by calculations of the gas‐phase IR spectra of 1–5 by DFT methods.
New Tetraphosphorus Ligands for Highly Linear Selective Hydroformylation of Allyl and Vinyl Derivatives
Authors: Cai Chaoxian , Yu Shichao , Cao Bonan , Zhang Xumu 
Published: July 2012

AbstractNew tetraphosphorus ligands have been developed and applied in the rhodium‐catalyzed regioselective hydroformylation of a variety of functionalized allyl and vinyl derivatives. Remarkably high linear selectivity was obtained by these tetraphosphorus ligands. The ligand that bears strong electron‐withdrawing 2,4‐difluorophenyl groups is the most effective one in affording linear aldehydes. The Rh/tetraphosphorus ligand catalyst is highly effective to produce linear aldehydes from functionalized allyl derivatives with heteroatoms or aromatic groups directly adjacent to the allyl group. For vinyl derivatives, the ligand is highly linear selective for acrylic derivatives, styrene, vinyl pyridine, and vinyl phthalimide. Linear to branch ratios of 26:1 and 10:1 were obtained for the hydroformylation of styrene and allyl cyanide, respectively.
Systemic Studies of Tetraphenylethene–Triphenylamine Oligomers and a Polymer: Achieving Both Efficient Solid‐State Emissions and Hole‐Transporting Capability
Authors: Liu Yang , Chen Xihan , Lv Yun , Chen Shuming , W. Y. Lam Jacky , Mahtab Faisal , Kwok Hoi Sing , Tao Xutang , Tang Ben Zhong 
Published: July 2012

AbstractBy employing a new synthetic strategy, a series of oligomers and a polymer composed of different number of tetraphenylethene and triphenylamine units was designed and synthesised. The optical physics properties and electroluminescence behaviours were studied comparatively. All the molecules demonstrate an aggregation‐induced emission (AIE) phenomenon and bear very high quantum yields in the solid state. The emission wavelengths and quantum efficiencies alternate with the change of the molecular configurations and achieve their maximum at the largest oligomer. The thermal stabilities also become higher along with the increase in the molecular weight. The molecules have suitable HOMO levels that match the work function of the indium tin oxide (ITO) anode. They can act as both light‐emitting and hole‐transporting materials in OLEDs. Thus the present strategy combines the intrinsic emissive nature of AIE materials and the good hole‐transport capability of aromatic amines, thereby achieving a win–win for both optical and electrical properties.
Bivalent Enzyme Inhibitors Discovered Using Dynamic Covalent Chemistry
Authors: Clipson Alexandra J. , Bhat Venugopal T. , McNae Iain , Caniard Anne M. , Campopiano Dominic J. , Greaney Michael F. 
Published: July 2012

AbstractA bivalent dynamic covalent chemistry (DCC) system has been designed to selectively target members of the homodimeric glutathione‐S‐transferase (GST) enzyme family. The dynamic covalent libraries (DCLs) use aniline‐catalysed acylhydrazone exchange between bivalent hydrazides and glutathione‐conjugated aldehydes and the bis‐hydrazides act as linkers to bridge between each glutathione binding site. The resultant DCLs were found to be compatible and highly responsive to templating with different GST isozymes, with the best results coming from the M and Schistosoma japonicum (Sj) class of GSTs, targets in cancer and tropical disease, respectively. The approach yielded compounds with selective, nanomolar affinity (Ki=61 nM for mGSTM1‐1) and demonstrates that DCC can be used to simultaneously interrogate binding sites on different subunits of a dimeric protein.
Stereocontrolled Total Synthesis of (+)‐trans‐Dihydronarciclasine
Authors: Hwang Soonho , Kim Deukjoon , Kim Sanghee 
Published: July 2012

AbstractA highly stereoselective and efficient total synthesis of trans‐dihydronarciclasine from a readily available chiral starting material was developed. The synthesis defines two of the five stereogenic centers of the natural product by an amino acid ester–enolate Claisen rearrangement. The other three stereogenic centers are created in a highly stereocontrolled fashion via a six‐ring vinylogous ester intermediate, which is generated from the γ,δ‐unsaturated ester functional group of the Claisen rearrangement product in an efficient three‐step sequence. This concise total synthesis exemplifies the use of a highly regioselective Friedel–Crafts‐type cyclization to form the B ring via an isocyanate intermediate derived from an N‐Boc group, which is superior to the conventional method using an imino triflate intermediate. This same N‐Boc group is employed to give high selectivity in the Claisen rearrangement earlier in the sequence.