bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probing the role of hydrogen bonds in the stability of base pairs in double‐helical DNA
Authors: Every Alicia E. , Russu Irina M. 
Published: July 2007

AbstractAromatic stacking and hydrogen bonding between nucleobases are two of the key interactions responsible for stabilization of DNA double‐helical structures. The present work aims at defining the specific contributions of these interactions to the stability of individual base pairs in DNA. The two DNA double helices investigated are formed, respectively, by the palindromic base sequences 5′‐dCCAACGTTGG‐3′ and 5′‐dCGCAGATCTGCG‐3′. The strength of the NH···N inter‐base hydrogen bond in each base pair is characterized from the measurement of the protium–deuterium fractionation factor of the corresponding imino proton using NMR spectroscopy. The structural stability of each base pair is evaluated from the exchange rate of the imino proton, measured by NMR. The results reveal that the fractionation factors of the imino protons in the two DNA double helices investigated fall within a narrow range of values, between 0.92 and 1.0. In contrast, the free energies of structural stabilization for individual base pairs span 3.5 kcal/mol, from 5.2 to 8.7 kcal/mol (at 15°C). These findings indicate that, in the two DNA double helices investigated, the strength of NH···N inter‐base hydrogen bonds does not change significantly depending on the nature or the sequence context of the base pair. Hence, the variations in structural stability detected by proton exchange do not involve changes in the strength of inter‐base hydrogen bonds. Instead, the results suggest that the energetic identity of a base pair is determined by the number of inter‐base hydrogen bonds, and by the stacking interactions with neighboring base pairs. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 165–173, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Mimicking Biological Cation‐Transport Based on Sphere‐Surface Supramolecular Chemistry: Simultaneous Interaction of Porous Capsules with Molecular Plugs and Passing Cations
Authors: Merca Alice , Haupt Erhard T. K. , Mitra Tamoghna , Bögge Hartmut , Rehder Dieter , Müller Achim 
Published: July 2007

AbstractSpherical capsules of the type [{(Mo)Mo5}12{Mo2(ligand)}30]n− exhibiting 20 {Mo9O9} pores with crown ether functions allowed us to perform a sophisticated study of the title phenomenon based on synthetic work as well as NMR spectroscopy. The pores of the host system interact in solution specifically with guests that can be noncovalently bonded, such as formamidinium and acetamidinium cations, while having different affinities to the pores. The exchange between the guest species present in solution and in the pores was investigated, including, besides the extreme scenarios of complete pore closing and complete opening, that of stepwise pore plugging. Because of this option it was possible to model for the first time passive transmembrane cation transport based on gated pores/channels. These have the appropriate dimensions and can even adopt different structure flexibilities in response to different cations. The present investigation is based on related syntheses as well as on numerous detailed 7Li NMR studies of Li+ transport/exchange equilibria in dependence of the pore environment/guest situations. One compound containing capsules with sulfate ligands (2) could be obtained in which all the pores are plugged with formamidinium cations and another corresponding one was obtained with additionally encapsulated Ca2+ ions (3); these were taken up after temporary release of some of the formamidinium plugs/guests upon short heating of the related solution.
Synthesis of New Self‐assembled PdII and PtII Rectangular Metallomacrocycles: A Comparative Study of their Inclusion Complexes
Authors: Chas Marcos , Abella Dolores , Blanco Víctor , Pía Elena , Blanco Gerardo , Fernández Antonio , Platas‐Iglesias Carlos , Peinador Carlos , Quintela José M. 
Published: July 2007

AbstractNew palladium and platinum metallocycles have been synthesized by reacting 4,4′‐bipyridinium‐based ligands with PdII and PtII complexes. Strict thermodynamic self‐assembly of 1 and [M(en)(NO3)2] (M=Pd, Pt) 6 a,b afforded metallocycles 7 a,b. However, the synthesis of 8 a,b and 9 a,b required a self‐assembly process that used sodium p‐phenylenediacetate (12) as a template. Finally, metallocycles 10 a,b were synthesized under high dilution conditions from ligand 4. The formation of inclusion complexes between metallocycles 7–10 and substrates 13 and 14 were studied by low‐temperature 1H NMR, and the association constants were determined in nitromethane and water by following the characteristic charge‐transfer band that these metallomacrocycles show in their UV‐visible absorption spectra. A clear correlation between the affinity for a substrate and the dimensions of the metallocycle was observed. Metallocycles 8 b and 9 b exhibited the highest binding constants in water and nitromethane. This observation is in agreement with the DFT (B3LYP)‐optimized geometries obtained for the different metallomacrocycles, which indicate that only macrocycles 8 and 9 possess a cavity with a width larger than 3.5 Å. The insertion of hydroquinone or diol 13 into the cavity of metallocycle 11 a was confirmed by single‐crystal X‐ray crystallography.
Analogy of the Coordination Chemistry of Alkaline Earth Metal and Lanthanide Ln2+ Ions: The Isostructural Zoo of Mixed Metal Cages [IM(OtBu)4{Li(thf)}4(OH)] (M=Ca, Sr, Ba, Eu), [MM′6(OPh)8(thf)6] (M=Ca, Sr, Ba, Sm, Eu, M′=Li, Na), and their Derivatives with 1,2‐Dimethoxyethane
Authors: Maudez William , Meuwly Markus , Fromm Katharina M. 
Published: July 2007

AbstractAs previously shown, alkali and alkaline earth metal iodides in nonaqueous, aprotic solvents behave like transition metal halides, forming cis‐ and trans‐dihalides with various neutral O‐donor ligands. These compounds can be used as precursors for the synthesis of new mixed alkali/alkaline earth metal aggregates. We show here that Ln2+ ions form isostructural cluster compounds. Thus, with LiOtBu, 50 % of the initial iodide can be replaced in MI2, M=Ca, Sr, Ba, Eu, to generate the mixed‐metal alkoxide aggregates [IM(OtBu)4{Li(thf)}4(OH)], for which the MOH contacts were investigated by theoretical methods. With M′OPh (M′=Li, Na), a new mixed‐metal aryloxide cluster type [MM′6(OPh)8(thf)6] is obtained for M=Ca, Sr, Ba, Sm, Eu. Their stability versus DME (DME=1,2‐dimethoxyethane) as bidentate ligand is studied.
The purchase versus illegal download of music by consumers: the influence of consumer response towards the artist and music
Authors: Ouellet Jean‐François 
Published: July 2007

AbstractBased on qualitative and quantitative surveys, I show that consumer responses toward a particular song and toward its performer(s) play distinct roles in explaining consumer choices to either buy or illegally download that song. The various types of consumer responses to songs and artists are first identified through qualitative research and then validated through exploratory and confirmatory factor analyses (CFA) of survey data. While consumer responses to music explain the need to reexperience and acquire the song, consumer responses to performers explain purchase over illegal downloading. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.
On solving the cracked‐beam problem by block method
Authors: Dosiyev A. A. , Cival Buranay S. 
Published: July 2007

AbstractAn extremely accurate solution is obtained for the cracked‐beam problem by one‐block version of the block method (BM). The obtained numerical results demonstrate the exponential convergence of the BM with respect to the number of quadrature nodes. A simple and high accurate formula to compute the stress intensity factor is given. The comparisons with other high accurate results in the literature have been carried out. Copyright © 2007 John Wiley & Sons, Ltd.
Judgments of body weight based on food intake: A pervasive cognitive bias among restrained eaters
Authors: Vartanian Lenny R. , Herman C. Peter , Polivy Janet 
Published: July 2007

AbstractObjective:Two studies examined the influence of meal‐size information on restrained and unrestrained eaters' judgments of body weight and size.Method:In Study 1, restrained and unrestrained eaters made body‐weight and body‐size judgments of a woman who had eaten either a small meal or a large meal. In Study 2, participants watched a video of a woman eating a small or large meal, and selected from two photographs of women's bodies (a heavier one and a thinner one), the woman whom they had seen in the video.Results:Restrained eaters were influenced by meal‐size information, judging women who had eaten a smaller meal as being thinner and weighing less (Study 1), and also choosing the thinner body to represent the woman who had eaten a smaller meal (Study 2). Unrestrained eaters were not influenced by food‐intake information.Conclusion:Restrained eaters' (but not unrestrained eaters') judgments of others appear to be biased by meal‐size information, suggesting that restrained eaters' food‐ and weight‐related cognitive biases might be more pervasive than has previously been assumed. © 2007 by Wiley Periodicals, Inc. Int J Eat Disord 2008
Ephrin‐A1 stimulates migration of CD8+CCR7+ T lymphocytes
Authors: Hjorthaug Hanne S. , Aasheim Hans‐Christian 
Published: July 2007

AbstractWe have previously demonstrated that binding of ephrin‐A1 to Eph receptors on human CD4+ T cells stimulates migration. Here, we show that a distinct population of CD8+ T lymphocytes, expressing the chemokine receptor CCR7, also binds ephrin‐A1 and is stimulated to migrate after binding. The Eph receptor signaling pathway taking part in the migration event was here investigated. Induced tyrosine phosphorylation of several proteins was seen after ephrin‐A1 binding. In particular, induced phosphorylation and kinase activity of the Src kinase family member Lck was observed. An Lck inhibitor inhibited ephrin‐A1‐induced migration, indicating the involvement of Lck in the migration event. In addition, we observed an induced association of the focal adhesion‐like kinase proline‐rich tyrosine kinase 2 (Pyk2) and the guanidine exchange factor Vav1 with Lck. PI3K inhibitors also inhibited migration, and studies in transfectants indicate an association of PI3K with EphA1. Further, ephrin‐A1‐induced migration could be related to the activation of Rho GTPases. This was also observed by using an inhibitor of the Rho‐associated kinase ROCK, a downstream effector of Rho. Our results suggest that stimulation of Eph receptors on CD8+CCR7+ T cells leads to migration involving activation of Lck, Pyk2, PI3K, Vav1 and Rho GTPase.
New Single‐Molecule Magnets by Site‐Specific Substitution: Incorporation of “Alligator Clips” into Fe4 Complexes
Authors: Barra Anne‐Laure , Bianchi Federica , Caneschi Andrea , Cornia Andrea , Gatteschi Dante , Gorini Lapo , Gregoli Luisa , Maffini Monica , Parenti Francesca , Sessoli Roberta , Sorace Lorenzo , Talarico Anna Maria 
Published: July 2007

Abstract“Alligator clips” suitable for grafting on H‐terminated silicon or gold surfaces have been incorporated into single‐molecule magnets (SMMs) of the Fe4 family. Tripodal ligands 2,2‐bis(hydroxymethyl)‐10‐undecen‐1‐ol (H3L1) and 11‐(acetylthio)‐2,2‐bis(hydroxymethyl)undecan‐1‐ol (H3L2) have been used to replace the six methoxide bridges in [Fe4(OMe)6(dpm)6], affording new Fe4 derivatives [Fe4(L1)2(dpm)6] (1) and [Fe4(L2)2(dpm)6] (2) in high yield (Hdpm = dipivaloylmethane). The molecular structures have been unambiguously established by XRD combined with ESI‐MS and magnetic characterization techniques, including DC and AC magnetometry and high‐frequency EPR spectroscopy. The two SMMs have an S = 5 ground state and an easy‐axis magnetic anisotropy leading to slow relaxation of the magnetization at low temperature, with effective anisotropy barriers of 15.9(2) K in 1 and 15.1(2) K in 2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Triuracils – 1,3‐Bis[ω‐(N‐methyluracil‐1‐yl)alkyl]thymines and Their 5,5′‐Cyclic Counterparts
Authors: Semenov Vyacheslav E. , Galiullina Leisan F. , Lodochnikova Olga A. , Kataeva Olga N. , Gubaidullin Aidar T. , Chernova Alla V. , Efremov Yurij Y. , Latypov Shamil K. , Reznik Vladimir S. 
Published: July 2007

AbstractA series of acyclic compounds with two 3,6‐dimethyluracil or 3‐methyluracil units attached to a a thymine or isocyanurate fragment by polymethylene or xylylene spacers are investigated. Ring‐closure reactions with paraformaldehyde in aqueous HCl in the presence of copper(I) chloride afforded pyrimidinophanes which can be considered macrocyclic counterparts of the acyclic triuracils. By X‐ray diffraction data the structures of the macrocycles in the solid state are characterised by a close arrangement of the uracil units, but there are no π‐π contacts between them. On the contrary, significant hypochromism of the macrocyclic triuracils compared with their acyclic counterparts indicates stacking between the thymine and 3,6‐dimethyluracil units in chloroform and H2O solutions. The conformational behaviour of the acyclic and macrocyclic compounds in solution has been determined by NMR, UV and computational methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Time‐domain BEM solution of convection–diffusion‐type MHD equations
Authors: Bozkaya N. , Tezer‐Sezgin M. 
Published: July 2007

AbstractThe two‐dimensional convection–diffusion‐type equations are solved by using the boundary element method (BEM) based on the time‐dependent fundamental solution. The emphasis is given on the solution of magnetohydrodynamic (MHD) duct flow problems with arbitrary wall conductivity. The boundary and time integrals in the BEM formulation are computed numerically assuming constant variations of the unknowns on both the boundary elements and the time intervals. Then, the solution is advanced to the steady‐state iteratively. Thus, it is possible to use quite large time increments and stability problems are not encountered. The time‐domain BEM solution procedure is tested on some convection–diffusion problems and the MHD duct flow problem with insulated walls to establish the validity of the approach. The numerical results for these sample problems compare very well to analytical results. Then, the BEM formulation of the MHD duct flow problem with arbitrary wall conductivity is obtained for the first time in such a way that the
equations are solved together with the coupled boundary conditions. The use of time‐dependent fundamental solution enables us to obtain numerical solutions for this problem for the Hartmann number values up to 300 and for several values of conductivity parameter. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of futures trading on the distribution of spot index returns: Implications for CVaR in the Spanish market
Authors: Illueca M. , Lafuente J.A. 
Published: July 2007

AbstractThere is extensive empirical research on the potential destabilizing effects of futures trading activity on spot market volatility. Rather than just focusing on spot volatility, the authors deal with the contemporaneous relationship between futures trading volume and the overall probability distribution of spot market returns. Empirical evidence using intraday data from the Spanish stock index futures market over the period 2000–2002 is provided. Their findings reveal that the density function of spot return conditional to spot volume depends on unexpected futures trading volume.
Organic matter accumulation during the Holocene in the Guadalquivir marshlands (SW Spain)
Authors: Ortiz José E. , Torres Trinidad , López‐Pamo José E. , Soler Vicente , Llamas Juan F. , Barettino Daniel , García María J. 
Published: July 2007

AbstractThe distribution of biomarker compounds and magnetic susceptibility observed in the sediment from a 20 m core drilled in the marshlands of the estuarine region of the Guadalquivir River (southwest coast of Spain) has allowed us to reconstruct the palaeoenvironmental evolution of this area during the Holocene. Several organic compounds (n‐alkanes, n‐ketones, n‐alkanols, n‐alkanoic acids and organic sulphur), as well as different biomarker ratios, have been used to show changing environmental conditions through time. These geochemical proxies suggest good preservation of the organic matter, although some diagenesis has occurred to particular organic compounds, especially the n‐alkanoic acids. Our data indicate a major allochthonous supply of terrestrial plants, with less influence from aquatic plants or algae through the core. There are markedly different palaeoenvironmental conditions between the uppermost 5 m (last 6 ka cal. B.P.) and the rest of the core. From 5 m (ca 6 ka cal. B.P.) to 19 m (ca 8 ka cal. B.P.) depth the palaeoenvironmental conditions were almost constant. Based on organic sulphur content and n‐alkane content logs, anoxic conditions prevailed from 8 to 6 ka cal. B.P., while oxic conditions with enhanced convection of water (prevalence of fluvial input), and consequently a greater organic matter supply, predominated in the upper 5 m of the core. Similarly, little variation in the magnetic susceptibility profile below 5 m indicates stable environmental conditions, while in the upper 5 m conditions shifted to one with elevated water input and clastic sediment supply. This is linked to palaeofloral alterations in the Guadiamar/Guadalquivir drainage basins and/or anthropogenic effects. We propose that from ca 8 to 6 ka cal. B.P. a stable landscape physiognomy in the surroundings of the estuarine area of the Guadalquivir River, with a predominance of pines and grassland. However, over the last 6 ka cal. B.P. a variation in the terrestrial plant biomarker compounds suggests an alternation of relatively dry and humid phases and/or the impact of human populations on altering the vegetation community have occurred. Copyright © 2007 John Wiley & Sons, Ltd.
Temporal lobe epilepsy: Differential pattern of damage in temporopolar cortex and white matter
Authors: Sankar Tejas , Bernasconi Neda , Kim Hosung , Bernasconi Andrea 
Published: July 2007

AbstractOur purpose was to quantify structural changes of the temporopolar cortex (TPC) and its white matter (TPWM) in temporal lobe epilepsy (TLE) using MRI volumetry and texture analysis. We studied 23 patients with hippocampal atrophy, and 20 healthy controls. Gradient magnitude and entropy were calculated to model signal intensity blurring on T1‐MRI. Two observers assessed signal changes and atrophy visually. Compared to controls, TLE patients had a decrease in TPC and TPWM volume ipsilateral to the seizure focus. The gradient magnitude and entropy were decreased ipsilateral to the focus only in TPWM, indicating blurring of this compartment. Eighty‐seven percent of TLE patients had at least one volumetric or textural abnormality. Although sensitivity of visual and quantitative assessment of TPC atrophy was comparable (43 and 39%), specificity was higher for volumetry (54% vs. 95%). Compared to visual analysis of signal changes in TPWM on T1‐MRI, texture metrics had higher sensitivity (65% vs. 17%) and specificity (100% vs. 69%). The proportion of patients with blurring of TPWM as determined by texture analysis was higher than that seen on visual inspection of T2 images (78% vs. 43%). We found no clear association between volumetric or textural changes of TPC and TPWM and outcome after surgery. Structural changes of the anatomically distinct TPC and TPWM are found ipsilateral to the seizure focus in the majority of TLE patients with hippocampal sclerosis. MRI post‐processing allows dissociating different pathological tissue characteristics and shows that atrophy involves gray and white matter, whereas blurring is confined to white matter. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.
Hippocampal mossy fiber sprouting and elevated trkB receptor expression following systemic administration of low dose domoic acid during neonatal development
Authors: Bernard Paul B. , MacDonald Debra S. , Gill Daphne A. , Ryan Catherine L. , Tasker R. Andrew 
Published: July 2007

AbstractWe have previously reported that serial systemic injections of low‐dose (subconvulsive) domoic acid (DOM) during early postnatal development produces changes in both behavior and hippocampal cytoarchitecture in aged rats (17 months) that are similar to those seen in existing animal models of temporal lobe epilepsy. Herein we report further hippocampal changes, consisting of mossy fiber sprouting and associated changes in the trkB receptor population in young adult (3 months) rats, and further, report that these changes show regional variation throughout the septo‐temporal axis of the hippocampus. Groups of Sprague Dawley rat pups were injected daily from postnatal day 8–14 with either saline (n = 23) or 20 μg/kg DOM (n = 25), tested for key indicators of neonatal neurobehavioral development, and then left undisturbed until ∼90 days of age, at which time brain tissue was removed, hippocampi were dissected, fixed and processed using either Timm's stain to visualize hippocampal mossy fiber sprouting (MFS) or trkB immunohistochemistry to visualize full length trkB receptors. Multiple sections from dorsal, mid, and ventral hippocampus were analyzed separately and all measures were conducted using image analysis software. The results indicate significant increases in MFS in the inner molecular layer in treated animals with corresponding changes in trkB receptor density. Further we identified significant increases in trkB receptor density in the hilus of the dentate gyrus and area CA3 and report increased mossy fiber terminal density in the stratum lucidum in treated rats. The magnitude of these changes differed between sections from dorsal, mid, and ventral hippocampus. We conclude that low dose neonatal DOM produces cytoarchitectural changes indicative of abnormal development and/or synaptic plasticity that are progressive with age and show regional variation within the hippocampal formation. © 2007 Wiley‐Liss, Inc.
When the bough breaks the cradle will fall: Promoting the health and well being of infants and toddlers in juvenile court
Authors: Lederman Cindy S. , Osofsky Joy D. , Katz Lynne 
Published: July 2007

AbstractApproximately one‐third of the children in the child welfare system are under the age of six. These children are almost invisible in our juvenile courts. It is now clear from the emerging science of early childhood development that during the first few years of life, children develop the foundation and capabilities on which all subsequent development builds. Living in emotional and environmental impoverishment and deprivation provides a poor foundation for healthy development. These very young and vulnerable children are exhibiting disproportionate developmental and cognitive delays, medical problems, and emotional disorders. However, there is growing evidence that early planned interventions can help. The juvenile court must take a leadership role in focusing on the very young child and learning more about risk, prevention, and early intervention in order to facilitate the healing process.