bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic and Mechanical Anisotropy in a Manganese 2‐Methylsuccinate Framework Structure
Authors: Li Wei , Barton Phillip T. , Kiran M. S. R. N. , Burwood Ryan P. , Ramamurty U. , Cheetham Anthony K. 
Published: September 2011

AbstractHybrid inorganic–organic framework materials exhibit unique properties that can be advantageously tuned through choice of the inorganic and organic components and by control of the crystal structure. We present a new hydrothermally prepared 3D hybrid framework, [Mn(2‐methylsuccinate)]n (1), comprising alternating 2D manganese oxide sheets and isolated MnO6 octahedra, pillared via syn, anti–syn carboxylates. Powder magnetic characterization shows that the compound is a homospin MnII ferrimagnet below 2.4 K. The easy‐axis is revealed by single‐crystal magnetic susceptibility studies and a magnetic structure is proposed. Anisotropic elastic moduli and hardness, observed through nanoindentation on differing crystal facets, were correlated with specific structural features. Such measurements of anisotropy are not commonly undertaken, yet allow for a more comprehensive understanding of structure–property relationships.
Oligocholate Foldamers as Carriers for Hydrophilic Molecules across Lipid Bilayers
Authors: Zhang Shiyong , Zhao Yan 
Published: September 2011

AbstractThree cholate foldamers were synthesized by the click reaction between an azide‐functionalized cholate trimer and different dialkynyl linkers. The foldamers were labeled with pyrene groups at the ends for their conformational study. The linkers between the two tricholate fragments were found to strongly influence the conformation of the foldamers in solution, as well as their ability to transport hydrophilic molecules across lipid bilayers. The folding of the oligocholates in mixed organic solvents was studied by fluorescence and UV/Vis spectroscopy. Although these molecules could not fold permanently in lipid bilayers, they were found to translocate carboxyfluorescein readily across by a carrier‐based mechanism. The transport is proposed to happen when the oligocholates adopt transiently folded structures with a hydrophobic exterior and a hydrophilic internal cavity. The transport rate strongly depended on the structure of the oligocholates and was sensitive even to the change of a single bond in a foldamer 3000 Da in MW. Better folded oligocholates in solution gave slower transport in the membranes.
A 5′‐Cap for DNA Probes Binding RNA Target Strands
Authors: Egetenmeyer Simone , Richert Clemens 
Published: September 2011

AbstractDetecting short RNA strands with high fidelity at any of the bases of their sequence, including the termini, can be challenging, since fraying, wobbling, and refolding all compete with canonical base pairing. We performed a search for 5′‐substituents of oligodeoxynucleotides that increase base pairing fidelity at the terminus of duplexes with RNA target strands. From a total of over 70 caps, differing in stacking moiety and linker, a phosphodiester‐linked sequence of the residues ofL‐prolinol, glycine, and oxolinic acid, dubbedogOA, was identified as a 5′‐cap that stabilizes any of the four canonical base pairs, with ΔTmvalues of up to +13.1 °C for an octamer. At the same time, the cap increases discrimination against any of the 12 possible terminal mismatches, including mismatches that are more stable than their perfectly matched counterparts in the control duplex, such as A:A. A probe with the cap also showed increased selectivity in the detection of two closely related microRNAs, let7c and let7a, with a ΔTmvalue of 9.2 °C. Melting curves also yielded thermodynamic data that shed light on the uniformity of molecular recognition in the sequence space of DNA:DNA and DNA:RNA duplexes. Hybridization probes with fidelity‐enhancing caps should find applications in the individual and parallel detection of biologically active RNA species.
Capping Ligand Perturbed Slow Magnetic Relaxation in Dysprosium Single‐Ion Magnets
Authors: Bi Ye , Guo Yun‐Nan , Zhao Lang , Guo Yang , Lin Shuang‐Yan , Jiang Shang‐Da , Tang Jinkui , Wang Bing‐Wu , Gao Song 
Published: September 2011

AbstractSingle‐ion magnets 1 and 2 and their diamagnetic analogues 3 and 4 for magnetic‐site dilution were obtained through substitution of the coordinated water molecules of [Ln(TTA)3(H2O)2] (Ln=Dy (1, 2), Y (3, 4); TTA=4,4,4‐trifluoro‐1‐(2‐thienyl)‐1,3‐butanedionate) by 2,2′‐bipyridine (1, 3) and 1,10‐phenanthroline (2, 4) capping ligands. Their structures and magnetic properties were investigated with the goal of identifying features relevant to modulating relaxation dynamics of single‐ion magnets. The metal ions in all complexes adopt an approximately square‐antiprismatic (SAP) O6N2 coordination environment. The SAP polyhedrons for both 1 and 2 show slight longitudinal compression, while the coordination sphere of 1 deviates more from an ideal SAP than that of 2, as indicated by the skew angles of the SAP environment. The similar values of Ueff for the two magnetically diluted samples imply nearly the same distribution of low‐lying states for their DyIII centers, which is consistent with the slight axial contraction observed for 1 and 2 and further corroborated by ligand‐field analysis. The fast quantum tunneling rate τQTM of 1, which is about ten times faster than that of 2, can presumably be associated with the larger rotation of the SAP surroundings. This distortion may result in a significant transverse anisotropy terms, and thus strongly affect the dynamic behavior of the system.
Stereoselective metabolism of fenoxaprop‐ethyl and its chiral metabolite fenoxaprop in rabbits
Authors: Zhang Yanfeng , Li Xuefeng , Shen Zhigang , Xu Xinyuan , Zhang Ping , Wang Peng , Zhou Zhiqiang 
Published: September 2011

AbstractThe stereoselective metabolism of the enantiomers of fenoxaprop‐ethyl (FE) and its primary chiral metabolite fenoxaprop (FA) in rabbits in vivo and in vitro was studied based on a validated chiral high‐performance liquid chromatography method. The information of in vivo metabolism was obtained by intravenous administration of racemic FE, racemic FA, and optically pure (−)‐(S)‐FE and (+)‐(R)‐FE separately. The results showed that FE degraded very fast to the metabolite FA, which was then metabolized in a stereoselective way in vivo: (−)‐(S)‐FA degraded faster in plasma, heart, lung, liver, kidney, and bile than its antipode. Moreover, a conversion of (−)‐(S)‐FA to (+)‐(R)‐FA in plasma was found after injection of optically pure (−)‐(S)‐ and (+)‐(R)‐FE separately. Either enantiomers were not detected in brain, spleen, muscle, and fat. Plasma concentration–time curves were best described by an open three‐compartment model, and the toxicokinetic parameters of the two enantiomers were significantly different. Different metabolism behaviors were observed in the degradations of FE and FA in the plasma and liver microsomes in vitro, which were helpful for understanding the stereoselective mechanism. This work suggested the stereoselective behaviors of chiral pollutants, and their chiral metabolites in environment should be taken into account for an accurate risk assessment. Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Neuron numbers in the hypothalamus of the normal aging rhesus monkey: Stability across the adult lifespan and between the sexes
Authors: Roberts D.E. , Killiany R.J. , Rosene D.L. 
Published: September 2011

AbstractNormal aging is accompanied by changes in hypothalamic functions including autonomic and endocrine functions and circadian rhythms. The rhesus monkey provides an excellent model of normal aging without the potential confounds of incipient Alzheimer's disease inherent in human populations. This study examined the hypothalamus of 51 rhesus monkeys (23 male, 18 female, 6.5–31 years old) using design‐based stereology to obtain unbiased estimates of neuron and glia numbers and the Cavalieri method to estimate volumes for eight reference spaces: total unilateral hypothalamus, suprachiasmatic nucleus (SCN), supraoptic nucleus (SON), paraventricular nucleus (PVN), dorsomedial nucleus (DM), ventromedial nucleus (VM), medial mammillary nucleus (MMN), and lateral hypothalamic area (LHA). The results demonstrated no age‐related difference in neuron number, glia number, or volume in any area in either sex except the PVN of male monkeys, which showed a significant increase in both neuron and glia numbers with age. Comparison of males and females for sexual dimorphisms revealed no significant differences in neuron number. However, males had more glia overall as well as in the SCN, DM, and LHA and had a larger hypothalamic volume overall and in the SCN, SON, VM, DM, and MMN. These results demonstrate that hypothalamic neuron loss cannot account for age‐related deficits in hypothalamic function and provides further evidence of the absence of neurodegeneration and cell death in the normal aging rhesus monkey. J. Comp. Neurol. 520:1181–1197, 2012. © 2011 Wiley Periodicals, Inc.
Cone outer segment extracellular matrix as binding domain for interphotoreceptor retinoid‐binding protein
Authors: Garlipp Mary Alice , Nowak Kevin R. , Gonzalez‐Fernandez Federico 
Published: September 2011

AbstractCones are critically dependent on interphotoreceptor retinoid‐binding protein (IRBP) for retinoid delivery in the visual cycle. Cone‐dominant vertebrates offer an opportunity to uncover the molecular basis of IRBP's role in this process. Here, we explore the association of IRBP with the interphotoreceptor matrix (IPM) of cones vs. rods in cone dominant retinas from chicken (Gallus domesticus), turkey (Meleagris gallopavo), and pig (Sus scrofa). Retinas were detached and fixed directly or washed in saline prior to fixation. Disassociated photoreceptors with adherent matrix were also prepared. Under 2 mM CaCl2, insoluble matrix was delaminated from saline washed retinas. The distribution of IRBP, as well as glycans binding peanut agglutinin (cone matrix) and wheat germ agglutinin (rod/cone matrix), was defined by confocal microscopy. Retina flat mounts showed IRBP diffusely distributed in an interconnecting, lattice‐like pattern throughout the entire matrix. Saline wash replaced this pattern with fluorescent annuli surrounding individual cone outer segments. In isolated cones and matrix sheets, IRBP colocalized with the peanut agglutinin binding matrix glycans. Our results reveal a wash‐resistant association of IRBP with a matrix domain immediately surrounding cone outer segments. The cone matrix sheath may be responsible for IRBP‐mediated cone targeting of 11‐cis retinoids. J. Comp. Neurol., 2012. © 2011 Wiley Periodicals, Inc.
Impact of Single Basepair Mismatches on Electron‐Transfer Processes at Fc‐PNA⋅DNA Modified Gold Surfaces
Authors: Hüsken Nina , Gębala Magdalena , Battistel Alberto , La Mantia Fabio , Schuhmann Wolfgang , Metzler‐Nolte Nils 
Published: September 2011

AbstractGold‐surface grafted peptide nucleic acid (PNA) strands, which carry a redox‐active ferrocene tag, present unique tools to electrochemically investigate their mechanical bending elasticity based on the kinetics of electron‐transfer (ET) processes. A comparative study of the mechanical bending properties and the thermodynamic stability of a series of 12‐mer Fc‐PNA⋅DNA duplexes was carried out. A single basepair mismatch was integrated at all possible strand positions to provide nanoscopic insights into the physicochemical changes provoked by the presence of a single basepair mismatch with regard to its position within the strand. The ET processes at single mismatch Fc‐PNA⋅DNA modified surfaces were found to proceed with increasing diffusion limitation and decreasing standard ET rate constants k0 when the single basepair mismatch was dislocated along the strand towards its free‐dangling Fc‐modified end. The observed ET characteristics are considered to be due to a punctual increase in the strand elasticity at the mismatch position. The kinetic mismatch discrimination with respect to the fully‐complementary duplex presents a basis for an electrochemical DNA sensing strategy based on the Fc‐PNA⋅DNA bending dynamics for loosely packed monolayers. In a general sense, the strand elasticity presents a further physicochemical property which is affected by a single basepair mismatch which may possibly be used as a basis for future DNA sensing concepts for the specific detection of single basepair mismatches.
Analytical Characteristics of Electrochemical Biosensor Using Pt‐Dispersed Graphene on Boron Doped Diamond Electrode
Authors: Song Min‐Jung , Kim Jong‐Hoon , Lee Seung‐Koo , Lim Dae‐Soon , Hwang Sung Woo , Whang Dongmok 
Published: September 2011

AbstractAn electrochemical biosensor was developed using Pt‐nanoparticles (Pt‐NPs) dispersed graphene based on a boron‐doped diamond thin film electrode. To compare its performances with those of other biosensors, glucose was used as a target analyte. This biosensor exhibited a wide linear range, a low detection limit and a higher sensitivity compared to other amperometric biosensors using graphene‐based electrodes. In addition, the biosensor promotes a direct electron transfer between the redox enzymes and the electrode surface and detects low concentration analytes. The excellent performance of the biosensor is attributed to the synergistic effect of the Pt‐NPs, graphene sheet and the BDD thin film. Therefore, it can be a promising application for electrochemical detection of analytes.
Direct Determination of Cadmium Traces in Natural Water by Adsorptive Stripping Voltammetry in the Presence of Cupferron as a Chelating Agent
Authors: Grabarczyk Malgorzata , Koper Anna 
Published: September 2011

AbstractA sensitive, simple and fast adsorptive stripping voltammetric procedure for trace determination of cadmium in natural samples containing high concentrations of surface active substances and humic substances has been developed. The method is based on adsorptive accumulation of the Cd(II)‐cupferron complex onto a hanging mercury drop electrode, followed by the reduction of the adsorbed species by a voltammetric scan using differential pulse modulation. The detection limit was 3×10−10 mol L−1 (33.6 ng L−1) with an accumulation time 30 s. The procedure was applied to the determination of Cd(II) in natural water samples without any pre‐treatment with satisfactory results.
Influence of Methyl Substituent Position on Redox Properties of Nitroaromatics Related to 2,4,6‐Trinitrotoluene
Authors: Chua Chun Kiang , Pumera Martin 
Published: September 2011

AbstractThe environmental remediation of military installation sites is very important due to frequently large presence of carcinogenic derivatives of explosives in the ground and in ground waters. These nitroaromatic explosives and their derivatives are assessed by sensing devices. It is highly important to have insight on the reasons affecting the reduction potentials of these compounds. The redox properties of mono‐, di‐ and tri‐nitroaromatic compounds are studied with cyclic voltammetry at a glassy carbon electrode for comparison. We show that the presence of a methyl group in the aromatic system leads into more negative reduction potentials. The ease of nitro group reduction vary from meta>para>ortho positions relative to a methyl group. The redox properties were also studied at various pH ranging from 2 to 10. Acidic environments facilitated the reduction processes at lower potentials. These findings will have a profound influence upon understanding the processes during reductive decontaminations of the polluted sites as well as for construction of highly sensitive sensors for their determination.
Forecast Evaluation of Nonlinear Models: The Case of Long‐Span Real Exchange Rates
Authors: Pavlidis Efthymios G. , Paya Ivan , Peel David A. 
Published: September 2011

ABSTRACTThis paper deals with the nonlinear modeling and forecasting of the dollar–sterling and franc–sterling real exchange rates using long spans of data. Our contribution is threefold. First, we provide significant evidence of smooth transition dynamics in the series by employing a battery of recently developed in‐sample statistical tests. Second, we investigate the small‐sample properties of several evaluation measures for comparing recursive forecasts when one of the competing models is nonlinear. Finally, we run a forecasting race for the post‐Bretton Woods era between the nonlinear real exchange rate model, the random walk, and the linear autoregressive model. The nonlinear model outperforms all rival models in the dollar–sterling case but cannot beat the linear autoregressive in the franc–sterling. Copyright © 2011 John Wiley & Sons, Ltd.
Tracking children's mental states while solving algebra equations
Authors: Anderson John R. , Betts Shawn , Ferris Jennifer L. , Fincham Jon M. 
Published: September 2011

AbstractBehavioral and function magnetic resonance imagery (fMRI) data were combined to infer the mental states of students as they interacted with an intelligent tutoring system. Sixteen children interacted with a computer tutor for solving linear equations over a six‐day period (Days 0–5), with Days 1 and 5 occurring in an fMRI scanner. Hidden Markov model algorithms combined a model of student behavior with multi‐voxel imaging pattern data to predict the mental states of students. We separately assessed the algorithms' ability to predict which step in a problem‐solving sequence was performed and whether the step was performed correctly. For Day 1, the data patterns of other students were used to predict the mental states of a target student. These predictions were improved on Day 5 by adding information about the target student's behavioral and imaging data from Day 1. Successful tracking of mental states depended on using the combination of a behavioral model and multi‐voxel pattern analysis, illustrating the effectiveness of an integrated approach to tracking the cognition of individuals in real time as they perform complex tasks. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Rhythm evokes action: Early processing of metric deviances in expressive music by experts and laymen revealed by ERP source imaging
Authors: James Clara E. , Michel Christoph M. , Britz Juliane , Vuilleumier Patrik , Hauert Claude‐Alain 
Published: September 2011

AbstractTo examine how musical expertise tunes the brain to subtle metric anomalies in an ecological musical context, we presented piano compositions ending on standard and deviant cadences (endings) to expert pianists and musical laymen, while high‐density EEG was recorded. Temporal expectancies were manipulated by substituting standard “masculine” cadences at metrically strong positions with deviant, metrically unaccented, “feminine” cadences. Experts detected metrically deviant cadences better than laymen. Analyses of event‐related potentials demonstrated that an early P3a‐like component (∼ 150–300 ms), elicited by musical closure, was significantly enhanced at frontal and parietal electrodes in response to deviant endings in experts, whereas a reduced response to deviance occurred in laymen. Putative neuronal sources contributing to the modulation of this component were localized in a network of brain regions including bilateral supplementary motor areas, middle and posterior cingulate cortex, precuneus, associative visual areas, as well as in the right amygdala and insula. In all these regions, experts showed enhanced responses to metric deviance. Later effects demonstrated enhanced activations within the same brain network, as well as higher processing speed for experts. These results suggest that early brain responses to metric deviance in experts may rely on motor representations mediated by the supplementary motor area and motor cingulate regions, in addition to areas involved in self‐referential imagery and relevance detection. Such motor representations could play a role in temporal sensory prediction evolved from musical training and suggests that rhythm evokes action more strongly in highly trained instrumentalists. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.
Accumulation of Cu, Pb, Ni and Zn in the halophyte plant Atriplex grown on polluted soil
Authors: Kachout Salma Sai , Mansoura Ameur Ben , Mechergui Rania , Leclerc Jean Claude , Rejeb Mohamed Nejib , Ouerghi Zeineb 
Published: September 2011

AbstractBACKGROUND: Three annual Atriplex species—A. hortensis var. purpurea, A. hortensis var. rubra and A. rosea—growing on soil with various levels of the heavy metals copper, lead, nickel, and zinc, have been investigated.RESULTS: Metal accumulation by Atriplex plants differed among species, levels of polluted soil and tissues. Metals accumulated by Atriplex were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. The increased concentration of heavy metals in soil led to increases in heavy metal shoot and root concentrations of Ni, Cu, Pb and Zn in plants as compared to those grown on unpolluted soil. Accumulation was higher in roots than shoots for all the heavy metals. None of the plants were suitable for phytoextraction because no hyperaccumulator was identified. However, plants with a high bioconcentration factor and low translocation factor have the potential for phytostabilization. Similarly, the correlation between metal concentrations and translocations in plants (BCFs and TFs) using a linear regression was also statistically significant.CONCLUSION: Among the plants studied, var. purpurea was the most efficient in accumulating Pb and Zn in its shoots, whereas var. rubra was most suitable for phytostabilization of sites contaminated with Cu and Ni. Copyright © 2011 Society of Chemical Industry
Conventional, organic and biodynamic farming: differences in polyphenol content and antioxidant activity of Batavia lettuce
Authors: Heimler Daniela , Vignolini Pamela , Arfaioli Paola , Isolani Laura , Romani Annalisa 
Published: September 2011

AbstractBACKGROUND: Lactuca sativa L. ssp. acephala L., cv. Batavia red Mohican plants were cultivated under intensive conventional, organic and biodynamic farming and were analyzed for their polyphenol content and antiradical activity in order to demonstrate the influence of farming on yield, polyphenol content and antiradical activity.RESULTS: The yield of plants from conventional farming was the highest (2.89 kg m−2), while polyphenol content, measured by spectrophotometry, of these plants was lower at P < 0.05 (1.36 mg g−1) than the content of plants from organic and biodynamic farming (1.74 and 1.85 mg g−1, respectively). The antiradical activity, measured by DPPH · assay, was positively correlated to flavonoid and hydroxycinnamic acid contents.CONCLUSION: Flavonoid, hydroxycinnamic acid and anthocyan patterns were not affected by the type of cultivation, while quantitative differences were demonstrated and some differences were found between conventional farming and organic or biodynamic farming. The yield of conventionally grown salads was the highest. Copyright © 2011 Society of Chemical Industry