bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals
Authors: Gámez Francisco , Hurtado Paola , Hortal Ana R. , Martínez‐Haya Bruno , Berden Giel , Oomens Jos 
Published: December 2012

AbstractThe benchmark inclusion complexes formed by α‐cyclodextrin (αCD) with alkali‐metal cations are investigated under isolated conditions in the gas phase. The relative αCD‐M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry, infrared action spectroscopy and quantum chemical computations. Solvent‐free laser desorption measurements reveal a trend of decreasing stability of the isolated complexes with increasing size of the cation guest. The experimental infrared spectra are qualitatively similar for the complexes with the four cations investigated, and are consistent with the binding of the cation within the primary face of the cyclodextrin, as predicted by the quantum computations (B3LYP/6‐31+G*). The inclusion of the quantum‐chemical cation disrupts the C6 symmetry of the free cyclodextrin to provide the optimum coordination of the cations with the ‐CH2OH groups in C1, C2 or C3 symmetry arrangements that are determined by the size of the cation.
Roles of Ion Transport in Control of Cell Motility
Authors: Stock Christian , Ludwig Florian T. , Hanley Peter J. , Schwab Albrecht 
Published: December 2012

AbstractCell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life‐threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage‐sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca2+and H+concentrations. Voltage‐sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca2+concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H+concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion‐transport mechanisms contribute to the various modes of cell motility. © 2013 American Physiological Society.Compr Physiol3:59‐119, 2013.
The Influence of Exercise on Cognitive Abilities
Authors: Gomez‐Pinilla Fernando , Hillman Charles 
Published: December 2012

AbstractScientific evidence based on neuroimaging approaches over the last decade has demonstrated the efficacy of physical activity improving cognitive health across the human lifespan. Aerobic fitness spares age‐related loss of brain tissue during aging, and enhances functional aspects of higher order regions involved in the control of cognition. More active or higher fit individuals are capable of allocating greater attentional resources toward the environment and are able to process information more quickly. These data are suggestive that aerobic fitness enhances cognitive strategies enabling to respond effectively to an imposed challenge with a better yield in task performance. In turn, animal studies have shown that exercise has a benevolent action on health and plasticity of the nervous system. New evidence indicates that exercise exerts its effects on cognition by affecting molecular events related to the management of energy metabolism and synaptic plasticity. An important instigator in the molecular machinery stimulated by exercise is brain‐derived neurotrophic factor, which acts at the interface of metabolism and plasticity. Recent studies show that exercise collaborates with other aspects of lifestyle to influence the molecular substrates of cognition. In particular, select dietary factors share similar mechanisms with exercise, and in some cases they can complement the action of exercise. Therefore, exercise and dietary management appear as a noninvasive and effective strategy to counteract neurological and cognitive disorders. © 2013 American Physiological Society.Compr Physiol3:403‐428, 2013.
Calcium Signaling in the Liver
Authors: Amaya Maria Jimena , Nathanson Michael H. 
Published: December 2012

AbstractIntracellular free Ca2+([Ca2+]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca2+signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca2+signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca2+signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca2+]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca2+signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca2+signaling in the liver, and the role of Ca2+signaling in liver disease. © 2013 American Physiological Society.Compr Physiol3:515‐539, 2013.
Iron Homeostasis in the Liver
Authors: Anderson Erik R. , Shah Yatrik M. 
Published: December 2012

AbstractIron is an essential nutrient that is tightly regulated. A principal function of the liver is the regulation of iron homeostasis. The liver senses changes in systemic iron requirements and can regulate iron concentrations in a robust and rapid manner. The last 10 years have led to the discovery of several regulatory mechanisms in the liver that control the production of iron regulatory genes, storage capacity, and iron mobilization. Dysregulation of these functions leads to an imbalance of iron, which is the primary cause of iron‐related disorders. Anemia and iron overload are two of the most prevalent disorders worldwide and affect over a billion people. Several mutations in liver‐derived genes have been identified, demonstrating the central role of the liver in iron homeostasis. During conditions of excess iron, the liver increases iron storage and protects other tissues, namely, the heart and pancreas from iron‐induced cellular damage. However, a chronic increase in liver iron stores results in excess reactive oxygen species production and liver injury. Excess liver iron is one of the major mechanisms leading to increased steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. © 2013 American Physiological Society.Compr Physiol3:315‐330, 2013.
Magnetic Poly(vinylpyridine)‐Coated Carbon Nanotubes: An Efficient Supramolecular Tool for Wastewater Purification
Authors: Maggini Laura , Raquez Jean‐Marie , Marega Riccardo , Jensen Ahrens Jennifer , Pineux Florent , Meyer Franck , Dubois Philippe , Bonifazi Davide 
Published: December 2012

AbstractHerein, we report the first example of a supramolecular carbon nanotube (CNT)‐based magnetic depolluting agent for divalent metal ion (M2+) removal from aqueous solutions. In particular, magnetic multi‐walled carbon nanotubes (m‐MWCNTs) coated with poly(vinylpyridine) (PVPy) self‐aggregate in aqueous solutions that contain divalent metal ions (such as Zn2+, Cu2+and Pb2+) to form tight insoluble bundles in which the M2+ions remain trapped through pyridyl–M2+–pyridyl interactions. Magnetic filtration ultimately affords the efficient separation of the depolluted solution from the precipitated M2+‐CNT agglomerates. Upon acid treatment, the supramolecular threads could be disassembled to afford the free CNT–polymer hybrid, thus allowing recycling of the depolluting agent. All materials and complexation/decomplexation steps were thoroughly characterised by using thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM and SEM, respectively). The quantification of the M2+residual concentrations in water was evaluated by using inductively coupled plasma optical emission spectroscopy (ICP‐OES), which showed that, depending on the metal cation, this material can remove up to 99 % of the contaminant.
A Flexible Metal‐Catalyzed Synthesis of Highly Substituted Aryl Phenanthrenyl Selenides
Authors: Lim Wontaeck , Rhee Young Ho 
Published: December 2012

AbstractAn efficient method for the preparation of diaryl selenides, which are important in biology and materials science, is described. Specifically, the development of highly substituted phenanthrenyl phenyl selenides 4 and 6 by metal‐catalyzed cyclization of o‐phenylarylalkynes species 1 was successfully performed. The selectivity for 9‐ and 10‐selenyl phenanthrenes was perfectly controlled by indium(III) and gold(I) catalysts, and the reactions proceed through different pathways. For the In(OTf)3 catalyst system, 6‐endo cyclization of alkyne 3 gives product 4 in which the selenium group is retained. In contrast, for the AuCl(IPr)/AgSbF6 catalyst system, transformation of metal–alkyne complex 2 into vinylidene–gold intermediate 5 gives product 6 in which the selenium group is migrated. Various substrates, even electronically poor substrates, can be converted into phenanthrenes with high selectivity in high yield under very mild conditions.
Energy and Charge Transfer Dynamics in Doped Semiconductor Nanocrystals
Authors: Chen Hsiang‐Yun , Son Dong Hee 
Published: December 2012

AbstractDoping semiconductor nanocrystals with transition metal ions introduces new optical, electronic, and magnetic properties to the host semiconductor nanocrystals. The energy transfer and charge transfer between exciton and dopant ions are the key photophysical processes responsible for the unique properties of doped semiconductor nanocrystals, which are distinct from their undoped counterparts. Since the energy transfer and charge transfer processes between exciton and dopant ions compete with the usual relaxation pathways of the exciton, competition among different dynamic processes ultimately determines the photophysical properties of doped nanocrystals. In this review, we discuss the dependence of the dynamics of the energy transfer and charge transfer processes in Mn‐doped II‐VI semiconductor nanocrystals on the structure of the host nanocrystal, spatial distribution of the dopant ions within the nanocrystal, and charge carrier‐trapping molecules near the surface of the nanocrystals.
A pilot study of macrophage responses to silk fibroin particles
Authors: Cui Xidong , Wen Jianchuan , Zhao Xia , Chen Xin , Shao Zhengzhong , Jiang Jack J. 
Published: December 2012

AbstractSilk fibroin (SF) shows promise for tissue engineering and other biomedical applications due to its excellent biocompatibility, unique biomechanical properties, and controllable biodegradability. The particulate form of SF materials may have many potential uses, including the use as a filler for tissue defects or as a controlled‐release agent for drug delivery. However, many past in vivo and in vitro studies evaluating the biocompatibility and biodegradability of SF have involved bulk implants. It is essential to evaluate the inflammatory effects of SF particles before further use. In this study, two different sizes of SF particles were evaluated to assess their impact on the release of tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, and IL‐6, in comparison with lipopolysaccharide positive control stimulation. The inflammatory processes were characterized using real‐time reverse transcription polymerase chain reaction, enzyme‐linked immunosorbent assay, and light microscopy evaluations. The results indicated that small silk fibroin particles and large silk fibroin particles, in culture with RAW 264.7 murine macrophage cells for 24 h, caused up‐regulation of mRNA coding for TNF‐α, which indicated that both size of particles have potential inflammatory effects. There was a statistically significant increase in this up‐regulation under small silk fibroin stimulation. However, the immunosorbent assay suggested that there was virtually no observed release of IL‐1β, IL‐6, or TNF‐α, relative to the control group. The results suggest that SF particles of the chosen dimensions may have good biocompatibility in culture with RAW 264.7 murine macrophages. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Influence of membrane cholesterol and substrate elasticity on endothelial cell spreading behavior
Authors: Hong Zhongkui , Ersoy Ilker , Sun Mingzhai , Bunyak Filiz , Hampel Paul , Hong Zhenling , Sun Zhe , Li Zhaohui , Levitan Irena , Meininger Gerald A. , Palaniappan Kannappan 
Published: December 2012

AbstractInteractions between implanted materials and the surrounding host cells critically affect the fate of bioengineered materials. In this study, the biomechanical response of bovine aortic endothelial cells (BAECs) with different membrane cholesterol levels to polyacrylamide (PA) gels was investigated by measuring cell adhesion and spreading behaviors at varying PA elasticity. The elasticity of gel substrates was manipulated by cross‐linker content. Type I collagen (COL1) was coated on PA gel to provide a biologically functional environment for cell spreading. Precise quantitative characterization of changes in cell area and perimeter of cells across two treatments and three bioengineered substrates were determined using a customized software developed for computational image analysis. We found that the initial response of endothelial cells to changes in substrate elasticity was determined by membrane cholesterol levels, and that the extent of endothelial cell spreading increases with membrane cholesterol content. All of the BAECs with different cholesterol levels showed little growth on substrates with elasticity below 20 kPa, but increased spreading at higher substrate elasticity. Cholesterol‐depleted cells were consistently smaller than control and cholesterol‐enriched cells regardless of substrate elasticity. These observations indicate that membrane cholesterol plays an important role in cell spreading on soft biomimetic materials constructed with appropriate elasticity. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Further insights in the ability of classical nonadditive potentials to model actinide ion–water interactions
Authors: Réal Florent , Trumm Michael , Schimmelpfennig Bernd , Masella Michel , Vallet Valérie 
Published: December 2012

AbstractPursuing our efforts on the development of accurate classical models to simulate radionuclides in complex environments (Réal et al., J. Phys. Chem. A 2010, 114, 15913; Trumm et al. J. Chem. Phys. 2012, 136, 044509), this article places a large emphasis on the discussion of the influence of models/parameters uncertainties on the computed structural, dynamical, and temporal properties. Two actinide test cases, trivalent curium and tetravalent thorium, have been studied with three different potential energy functions, which allow us to account for the polarization and charge‐transfer effects occurring in hydrated actinide ion systems. The first type of models considers only an additive energy term for modeling ion/water charge‐transfer effects, whereas the other two treat cooperative charge‐transfer interactions with two different analytical expressions. Model parameters are assigned to reproduce high‐level ab initio data concerning only hydrated ion species in gas phase. For the two types of cooperative charge‐transfer models, we define two sets of parameters allowing or not to cancel out possible errors inherent to the force field used to model water/water interactions at the ion vicinity. We define thus five different models to characterize the solvation of each ion. For both ions, our cooperative charge‐transfer models lead to close results in terms of structure in solution: the coordination number is included within 8 and 9, and the mean ion/water oxygen distances are 2.45 and 2.49 Å, respectively, for Th(IV) and Cm(III). © 2012 Wiley Periodicals, Inc.
Nanostructure Transitions and Their Relation to Mechanical Properties in Polyethylene/Polyamide 6 Microfibrillar Composites as Revealed by SAXS/Straining Studies
Authors: Dencheva Nadya , Denchev Zlatan , Stribeck Norbert , Motovilin Mladen , Zeinolebadi Ahmad , Funari Sergio S. , Botta Stephan 
Published: December 2012

AbstractMicrofibrillar composites (MFC) with a matrix of high‐density polyethylene (HDPE) and reinforcements of polyamide 6 (PA6) are tensile tested while collecting 2D small‐angle X‐ray scattering patterns. The scattering of the isotropic matrix is separated from that of the oriented fibrils and the chord distribution functions (CDF) are computed. The changes in CDF peaks during the stretching process are registered and related to the nanostructure evolution in the samples. It is demonstrated how compatibilization of the HDPE and PA6 components and additional reinforcement of the PA6 fibrils with nanoclays influence the nanostructure of the fibrils and the mechanical behavior of the MFCs. The structural changes in the transcrystalline HDPE are consistent with a reversible strain‐induced crystallization.
Facile Synthesis of Multicompartment Micelles Based on Biocompatible Poly(3‐hydroxyalkanoate)
Authors: Babinot Julien , Renard Estelle , Le Droumaguet Benjamin , Guigner Jean‐Michel , Mura Simona , Nicolas Julien , Couvreur Patrick , Langlois Valérie 
Published: December 2012

AbstractIn this paper, a straightforward method to produce poly(3‐hydroxyalkanoate)‐based multicompartment micelles (MCMs) is presented. Thiol‐ene addition is used to graft sequentially perfluorooctyl chains and poly(ethylene glycol) oligomers onto poly(3‐hydroxyoctanoate‐co‐hydroxyundecenoate) oligomers backbone. Well‐defined copolymers are obtained as shown by 1H NMR and size‐exclusion chromatography. After nanoprecipitation in water, novel PHA‐based MCMs are evidenced by cryo‐transmission electron microscopy. Moreover, the cytocompatibility of MCMs is demonstrated in vitro via cell viability assay.
Raising the Roof: The Preferential Pharmacological Stimulation of Th1 and Th2 Responses Mediated by NKT Cells
Authors: East James E. , Kennedy Andrew J. , Webb Tonya J. 
Published: December 2012

AbstractNatural killer T (NKT) cells serve as a bridge between the innate and adaptive immune systems, and manipulating their effector functions can have therapeutic significances in the treatment of autoimmunity, transplant biology, infectious disease, and cancer. NKT cells are a subset of T cells that express cell‐surface markers characteristic of both natural killer cells and T cells. These unique immunologic cells have been demonstrated to serve as a link between the innate and adaptive immune systems through their potent cytokine production following the recognition of a range of lipid antigens, mediated through presentation of the major histocompatibility complex (MHC) class I like CD1d molecule, in addition to the NKT cell's cytotoxic capabilities upon activation. Although a number of glycolipid antigens have been shown to complex with CD1d molecules, most notably the marine sponge derived glycolipid alpha‐galactosylceramide (α‐GalCer), there has been debate as to the identity of the endogenous activating lipid presented to the T‐cell receptor (TCR) via the CD1d molecule on antigen‐presenting cells (APCs). This review aims to survey the use of pharmacological agents and subsequent structure–activity relationships (SAR) that have given insight into the binding interaction of glycolipids with both the CD1d molecules as well as the TCR and the subsequent immunologic response of NKT cells. These studies not only elucidate basic binding interactions but also pave the way for future pharmacological modulation of NKT cell responses.
Cycloolefin Copolymers by Early and Late Transition Metal Catalysts
Authors: Tritto Incoronata , Boggioni Laura , Ravasio Andrea , Scalcione Giulia 
Published: December 2012

AbstractThe complex [Pd(κ2‐P,O‐{2‐(2‐MeOC6H4)2P}C6H4SO3)Me(dmso)] (1) is investigated for the copolymerization of (E) with norbornene (N) and functionalized N derivatives affording P(E‐co‐N) in excellent yields. Copolymer molar masses are higher than those of PE and increase with N concentration. In addition, the complex [Ti(κ2‐N,O‐{2,6‐F2C6H3N = C(Me)C(H) = C(CF3)O})2Cl2] (2) is evaluated as catalyst for living E‐co‐N copolymerization upon activation with dried methylaluminoxane between 25 and 90 °C. Copolymerization at different [N]/[E] feed ratios affords stereoirregular alternating high molar mass P(E‐co‐N) with narrow molar mass distribution. P(E‐co‐N) living copolymerization is demonstrated by kinetics at 50 °C. Block copolymers are synthesized and fully characterized. magnified image
Verification of the fitted crystal‐field Hamiltonian parametrization by the crystal‐field splitting second moment
Authors: Mulak Maciej , Mulak Jacek 
Published: December 2012

AbstractA physically valid parametrization of the crystal‐field (CF) Hamiltonian HCF has to reproduce not only the energy of Stark sublevels but also the multipolar structure of the central ion surroundings. The square of the second moment $\sigma {}^{2} {\left( {\left| {J} \right\rangle } \right)}$ of $\left| {J} \right\rangle $ electronic state CF splitting must be a superposition of squares of the second moments of the partial splittings produced separately by the individual multipoles: $\sigma {}^{2} {\left( {\left| {J} \right\rangle } \right)} = \sum\nolimits_{k} {\sigma _{k}^{2} } {\left( {\left| {J} \right\rangle } \right)} = {\left[ {1/(2J + 1)} \right]}\sum\nolimits_{k} {A_{k}^{2} {\left( {\left| {J} \right\rangle } \right)}} S_{k}^{2} $, where $A_{k} {\left( {\left| {J} \right\rangle } \right)}$ represents the modulus of a k‐rank multipole of the central ion electronic eigenstate $\left| {J} \right\rangle $, whereas $S_{k} = {\left( {[1/(2k + 1)]\sum\nolimits_{q} {\left| {B_{kq} } \right|^{2} } } \right)}^{1/2} $ is the k‐rank CF strength. The relationship between $\sigma {}^{2} {\left( {\left| {J} \right\rangle } \right)}$ known from experiment and $S_{k}^{2} $ obtained from fitting procedure allows us to verify whether the parametrization is physically valid. It is demonstrated by several examples of CF splittings of electronic states of trivalent lanthanide ions in different crystal matrices. The approach is confined only to the states with good quantum numbers J. Nevertheless, by finding such states in any analyzed spectrum, the method can provide the actual multipole characteristics of HCF, and plays the role of a preparametrization. In general, the stepwise fitting procedure can never lead to parametrizations with a correct multipolar structure due to the limitation of the initial eigenfunctions. In consequence, the pertinent crystal‐field parameters (CFPs) are burdened with a methodical inherent fault. The loss of physical meaning of fitted CFPs, its source and consequences, constitute the main theme of the paper.