bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of hERG1 channel role in mouse colorectal carcinogenesis
Authors: Fiore Antonella , Carraresi Laura , Morabito Angela , Polvani Simone , Fortunato Angelo , Lastraioli Elena , Femia Angelo P. , De Lorenzo Emanuele , Caderni Giovanna , Arcangeli Annarosa 
Published: July 2013

AbstractThe human ether‐à‐go‐go‐related gene (hERG)1 K+ channel is upregulated in human colorectal cancer cells and primary samples. In this study, we examined the role of hERG1 in colorectal carcinogenesis using two mouse models: adenomatous polyposis coli (Apcmin/+) and azoxymethane (AOM)‐treated mice. Colonic polyps of Apcmin/+ mice overexpressed mERG1 and their formation was reverted by the hERG1 blocker E4031. AOM was applied to either hERG1‐transgenic (TG) mice, which overexpress hERG1 in the mucosa of the large intestine, or wild‐type mice. A significant increase of both mucin‐depleted foci and polyps in the colon of hERG1‐TG mice was detected. Both the intestine of TG mice and colonic polyps of Apcmin/+ showed an upregulation of phospho‐Protein Kinase B (pAkt)/vascular endothelial growth factor (VEGF‐A) and an increased angiogenesis, which were reverted by treatment with E4031. On the whole, this article assigns a relevant role to hERG1 in the process of in vivo colorectal carcinogenesis.
Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl‐Substituted para‐Phenylene Spacers
Authors: Ferrando‐Soria Jesús , Castellano María , Ruiz‐García Rafael , Cano Joan , Julve Miguel , Lloret Francesc , Ruiz‐Pérez Catalina , Pasán Jorge , Cañadillas‐Delgado Laura , Armentano Donatella , Journaux Yves , Pardo Emilio 
Published: July 2013

AbstractDouble‐stranded anionic dinuclear copper(II) metallacyclic complexes of the paracyclophane type [Cu2L2]4− have been prepared by the CuII‐mediated self‐assembly of different para‐phenylenebis(oxamato) bridging ligands with either zero‐, one‐, or four‐electron‐donating methyl substituents (L=N,N′‐para‐phenylenebis(oxamate) (ppba; 1), 2‐methyl‐ N,N′‐para‐phenylenebis(oxamate) (Meppba; 2), and 2,3,5,6‐tetramethyl‐ N,N′‐para‐phenylenebis(oxamate) (Me4ppba; 3)). These complexes have been isolated as their tetra‐n‐butylammonium (1 a–3 a), lithium(I) (1 b–3 b), and tetraphenylphosphonium salts (1 c–3 c). The X‐ray crystal structures of 1 a and 3 c show a parallel‐displaced π‐stacked conformation with a smaller deviation from perpendicularity between the two benzene rings and the basal planes of the square planar CuII ions when increasing the number of methyl substituents (average dihedral angles (ϕ) of 58.72(7) and 73.67(5)° for 1 a and 3 c, respectively). Variable‐temperature (2.0–300 K) magnetic‐susceptibility measurements show an overall increase of the intramolecular antiferromagnetic coupling with the number of methyl substituents onto the para‐phenylene spacers (−J=75–95, 100–124, and 128–144 cm−1 for 1 a–c, 2 a–c, and 3 a–c, respectively; H=−JS1×S2). Cyclic voltammetry (CV) measurements show a reversible one‐electron oxidation of the double polymethyl‐substituted para‐phenylenediamidate bridging skeleton at a relatively low formal potential that decreases with the number of methyl substituents (E1=+0.33, +0.24, and +0.15 V vs. SCE for 1–3, respectively). The monooxidized dicopper(II) π‐radical cation species 3′ prepared by the chemical oxidation of 3 with bromine exhibits intense metal‐to‐ligand charge‐transfer (MLCT) transitions in the visible and near‐IR (λmax=595 and 875 nm, respectively) regions together with a rhombic EPR signal with a seven‐line splitting pattern due to hyperfine coupling with the nuclear spin of the two CuII ions. Density functional (DF) calculations for 3′ evidence a characteristic iminoquinonoid‐type short‐long‐short alternating sequence of CN and CC bonds for both tetramethyl‐para‐phenylenediamidate bridges and a large amount of spin density of negative sign mainly delocalized along each of the four benzene C atoms directly attached to the amidate N atoms, which is in agreement with a fully delocalized π‐stacked monoradical ligand description. Hence, the spins of the two CuII ions (SCu=1/2) that are antiparallel aligned in 3 (OFF state) become parallel in 3′ (ON state). Further developments may be then envisaged for this new permethylated dicopper(II) paracyclophane with a redox noninnocent ligand as a prototype for molecular magnetic electroswitch.
Diazadithia[7]helicenes: Synthetic Exploration, Solid‐State Structure, and Properties
Authors: Waghray Deepali , Cloet Arvid , Van Hecke Kristof , Mertens Stijn F. L. , De Feyter Steven , Van Meervelt Luc , Van der Auweraer Mark , Dehaen Wim 
Published: July 2013

AbstractDiazadithia[7]helicenes were synthesized from the readily available building block ethyl 7‐chloro‐8‐formylthieno[3,2‐f]quinoline‐2‐carboxylate by a Wittig reaction–photocyclization strategy. The helicene core was functionalized by nucleophilic aromatic substitution with a variety of nucleophiles (e.g., O‐, N‐, and C‐centered) and palladium‐catalyzed reactions such as Suzuki coupling and Buchwald–Hartwig amination. Racemization studies confirmed that the enantiopure forms of these [7]helicenes are conformationally stable compared to their lower analogues. The solid‐state structures of the novel diazadithia[7]helicenes were determined by single‐crystal X‐ray diffraction. The crystal structures of these azathia[7]helicenes show columnar stacking in antiparallel fashion. The HOMO–LUMO gaps of the new compounds were determined on the basis of electrochemical and optical measurements.
Design and Synthesis of a γ1β8‐Cyclodextrin Oligomer: A New Platform with Potential Application as a Dendrimeric Multicarrier
Authors: Barge Alessandro , Caporaso Marina , Cravotto Giancarlo , Martina Katia , Tosco Paolo , Aime Silvio , Carrera Carla , Gianolio Eliana , Pariani Giorgio , Corpillo Davide 
Published: July 2013

AbstractWe report the synthesis and characterization of a water‐soluble, star‐shaped macromolecular platform consisting of eight β‐cyclodextrin (β‐CD) units anchored to the narrower rim of a γ‐CD core through bis(triazolyl)alkyl spacers. The efficient synthetic protocol is based on the microwave (MW)‐promoted Cu‐catalyzed 1,3‐dipolar cycloaddition of CD monoazides to CD monoacetylenes. The ligand‐hosting capability of the construct has been assessed by relaxometric titration and nuclear magnetic relaxation dispersion (NMRD) profiling, which showed it to be good, and this was supported by molecular dynamics simulations. To demonstrate the feasibility of obtaining supramolecular structures with high hosting ability, we designed a dimeric platform, formed by joining two nonamers through the γ‐CD cores through a bis(lithocholic acid) linker. With a view to the potential biological applications, cytotoxicity and extent of binding to human serum albumin were assessed. The properties of this dendrimeric multicarrier make it suitable for pharmaceutical and diagnostic purposes, ranging from targeted drug delivery to molecular imaging.
Tetraalkoxyphenanthrene‐Fused Dehydroannulenes: Synthesis, Self‐Assembly, and Electronic, Optical, and Electrochemical Properties
Authors: Kato Shin‐ichiro , Takahashi Nobutaka , Tanaka Hidekazu , Kobayashi Atsushi , Yoshihara Toshitada , Tobita Seiji , Yamanobe Takeshi , Uehara Hiroki , Nakamura Yosuke 
Published: July 2013

AbstractNovel tetraalkoxyphenanthrene‐fused dehydro[12]‐, [18]‐, and [24]annulenes 1–3 were synthesized by using Cu‐mediated or Pd‐catalyzed oxidative macrocyclization reactions as key steps, and their electronic, optical, and electrochemical properties have been investigated in detail. X‐ray crystallographic analysis of a single crystal of 1 a demonstrated that the molecules were arranged longitudinally in a slipped π‐stacked fashion to form a 1D column. 1H NMR and UV/Vis spectroscopic and cyclic voltammetric analysis in conjugation with nucleus‐independent chemical shift (NICS) calculations for 1–3 support that the annulation at the 9,10‐positions of phenanthrene to the dehydroannulene ring enhances the tropicity and decreases the HOMO–LUMO gaps of the molecules relative to the benzannulation and that 1 possesses an antiaromatic character. Self‐association behavior due to π–π stacking in CDCl3 was observed for 1 and 2 and was quantified by concentration‐dependent 1H NMR spectroscopic measurements. The self‐assembly of 1 and 2 into well‐defined 1D superstructures with high aspect ratios were obtained, and the morphology and crystallinity of these compounds were investigated by means of SEM and wide‐angle X‐ray diffraction (WAXD) measurements. Furthermore, it was shown that 1 b and 2 b display liquid‐crystalline phases by means of differential scanning calorimetry, polarizing optical microscopy, and variable‐temperature WAXD measurements.
Enantiomeric Separation of 13 New Amphetamine‐Like Designer Drugs by Capillary Electrophoresis, Using Modified‐‐Cyclodextrins
Authors: Burrai Lucia , Nieddu Maria , Pirisi Maria Antonietta , Carta Antonio , Briguglio Irene , Boatto Gianpiero 
Published: July 2013

ABSTRACTAn easy‐to‐prepare chiral CE method for the enantiomeric separation of 13 new amphetamine‐like designer drugs, using CDs as chiral selectors, was developed. Sulfated‐β‐CD was found to be the best chiral selector among the three used (sulfated‐β‐CD, caroboxymethyl‐β‐CD, dimethyl‐β‐CD). The separation of the analytes was achieved in a fused‐silica gel capillary at 20 °C using an applied voltage of +25 kV. The optimized background electrolyte consisted of 63.5 mM H3PO4 and 46.9 mM NaOH in water. Several electrophoretic parameters such as CD type, CD concentration (1 − 40 mg/mL), buffer pH (2.6, 3.6, 5.0, 6.0), length of the capillary (70 − 40 cm total length), amount of the organic solvent (methanol and acetonitrile) were investigated and optimized. Chirality 25:617–621, 2013. © 2013 Wiley Periodicals, Inc.
Supramolecular Host‐Inhibited Excited‐State Proton Transfer and Fluorescence Switching of the Anti‐Cancer Drug, Topotecan
Authors: Gavvala Krishna , Sengupta Abhigyan , Koninti Raj Kumar , Hazra Partha 
Published: July 2013

AbstractThe effect of cucurbit[7]uril (CB[7]) nano‐caging on the photophysical properties, particularly excited‐state proton transfer (ESPT) reaction, of an eminent anti‐cancer drug, topotecan (TPT), is demonstrated through steady‐state and time‐resolved fluorescence measurements. TPT in water (pH 6) exists exclusively as the cationic form (C) in the ground state. However, the drug emission mainly comes from the excited‐state zwitterionic form (Z*) of TPT, and is attributed to water‐assisted ESPT between the 10‐hydroxyl group and water, which leads to the transformation of C* to Z* of TPT. In the presence of CB[7], it is found that selective encapsulation of the C form of TPT results in the formation of a 1:1 inclusion complex (CB[7]:TPT), and the ESPT process is inhibited by this encapsulation process. As a result, C* becomes the dominant emitting species in the presence of CB[7] rather than Z*, and fluorescence switching takes place from green to blue. Time‐resolved studies also support the existence of CB[7]‐encapsulated cationic species as the major emitting species in the presence of the macrocyclic host. Semi‐empirical quantum chemical calculations are employed to gain insight into the molecular picture of orientation of TPT in the inclusion complex. It is clearly seen from the optimised structure of 1:1 CB[7]:TPT inclusion complex that both 10‐hydroxyl and 9‐dimethylaminomethylene groups of TPT lie partly inside the cavity, and thereby inhibit the excited‐state transformation of C* to Z* by the ESPT process. Finally, controlled release of the drug is achieved by means of fluorescence switching by introducing NaCl, which is rich in cells, as an external stimulus.
Fuzzy step size least mean square algorithm tuned linearly constrained constant modulus algorithm for multi‐carrier code division multiple access blind multiuser detector
Authors: Hung Ho‐Lung , Cheng Chia‐Hsin 
Published: July 2013

ABSTRACTAdaptive fuzzy logic step size least mean square algorithm (FLCLMS) tuning unit is designed to adjust the step size of the linear constrained constant modulus algorithm for blind multiuser detection (MUD) in multi‐carrier code division multiple access (MC‐CDMA) systems is presented. In wireless communications system, the conventional constant modulus algorithm for blind MUD has some disadvantages such as slow convergence speed and phase rotation. To overcome these shortages, a modified constant modulus algorithm was developed for blind multiuser detector. On the basis of the deterministic behavior of the FLCLMS algorithm, it has also proposed simplification over the cost function calculation, obtaining more efficient algorithm and creating new perspective for the MUD implementation. The proposed algorithm ensures the algorithm convergence to the desired user and suppresses the multiple access interference in this cost function. Thus, the performance of the system is improved. The computational experiments show that the proposed FLCLMS not only can find optimal or closed‐to‐optimal solutions but also can obtain the low computation complexity both better and more robust results than existing algorithm reported recently in the literature. Copyright © 2013 John Wiley & Sons, Ltd.
Phenological overlap of interacting species in a changing climate: an assessment of available approaches
Authors: Rafferty Nicole E. , CaraDonna Paul J. , Burkle Laura A. , Iler Amy M. , Bronstein Judith L. 
Published: July 2013

AbstractConcern regarding the biological effects of climate change has led to a recent surge in research to understand the consequences of phenological change for species interactions. This rapidly expanding research program is centered on three lines of inquiry: (1) how the phenological overlap of interacting species is changing, (2) why the phenological overlap of interacting species is changing, and (3) how the phenological overlap of interacting species will change under future climate scenarios. We synthesize the widely disparate approaches currently being used to investigate these questions: (1) interpretation of long‐term phenological data, (2) field observations, (3) experimental manipulations, (4) simulations and nonmechanistic models, and (5) mechanistic models. We present a conceptual framework for selecting approaches that are best matched to the question of interest. We weigh the merits and limitations of each approach, survey the recent literature from diverse systems to quantify their use, and characterize the types of interactions being studied by each of them. We highlight the value of combining approaches and the importance of long‐term data for establishing a baseline of phenological synchrony. Future work that scales up from pairwise species interactions to communities and ecosystems, emphasizing the use of predictive approaches, will be particularly valuable for reaching a broader understanding of the complex effects of climate change on the phenological overlap of interacting species. It will also be important to study a broader range of interactions: to date, most of the research on climate‐induced phenological shifts has focused on terrestrial pairwise resource–consumer interactions, especially those between plants and insects.
How landscape scale changes affect ecological processes in conservation areas: external factors influence land use by zebra (Equus burchelli) in the Okavango Delta
Authors: Bartlam‐Brooks Hattie L. A. , Bonyongo Mpaphi C. , Harris Stephen 
Published: July 2013

AbstractMost large‐bodied wildlife populations in sub‐Saharan Africa only survive in conservation areas, but are continuing to decline because external changes influence ecological processes within reserves, leading to a lack of functionality. However, failure to understand how landscape scale changes influence ecological processes limits our ability to manage protected areas. We used GPS movement data to calculate dry season home ranges for 14 zebra mares in the Okavango Delta and investigated the effects of a range of landscape characteristics (number of habitat patches, mean patch shape, mean index of juxtaposition, and interspersion) on home range size. Resource utilization functions (RUF) were calculated to investigate how specific landscape characteristics affected space use. Space use by all zebra was clustered. In the wetter (Central) parts of the Delta home range size was negatively correlated with the density of habitat patches, more complex patch shapes, low juxtaposition of habitats and an increased availability of floodplain and grassland habitats. In the drier (Peripheral) parts of the Delta, higher use by zebra was also associated with a greater availability of floodplain and grassland habitats, but a lower density of patches and simpler patch shapes. The most important landscape characteristic was not consistent between zebra within the same area of the Delta, suggesting that no single foraging strategy is substantially superior to others, and so animals using different foraging strategies may all thrive. The distribution and complexity of habitat patches are crucial in determining space use by zebra. The extent and duration of seasonal flooding is the principal process affecting habitat patch characteristics in the Okavango Delta, particularly the availability of floodplains, which are the habitat at greatest risk from climate change and anthropogenic disturbance to the Okavango's catchment basin. Understanding how the factors that determine habitat complexity may change in the future is critical to the conservation of large mammal populations. Our study shows the importance of maintaining flood levels in the Okavango Delta and how the loss of seasonal floodplains will be compounded by changes in habitat configuration, forcing zebra to change their relative space use and enlarge home ranges, leading to increased competition for key resources and population declines.
Genetic attributes of midwife toad (Alytes obstetricans) populations do not correlate with degree of species decline
Authors: Tobler Ursina , Garner Trenton W. J. , Schmidt Benedikt R. 
Published: July 2013

AbstractGenetic diversity is crucial for long‐term population persistence. Population loss and subsequent reduction in migration rate among the most important processes that are expected to lead to a reduction in genetic diversity and an increase in genetic differentiation. While the theory behind this is well‐developed, empirical evidence from wild populations is inconsistent. Using microsatellite markers, we compared the genetic structure of populations of an amphibian species, the midwife toad (Alytes obstetricans), in four Swiss regions where the species has suffered variable levels of subpopulation extirpation. We also quantified the effects of several geographic factors on genetic structure and used a model selection approach to ascertain which of the variables were important for explaining genetic variation. Although subpopulation pairwise FST‐values were highly significant even over small geographic scales, neither any of the geographic variables nor loss of subpopulations were important factors for predicting spatial genetic structure. The absence of a signature of subpopulation loss on genetic differentiation may suggest that midwife toad subpopulations function as relatively independent units.
Vegetation induced changes in the stable isotope composition of near surface humidity
Authors: Simonin Kevin A. , Link Percy , Rempe Daniella , Miller Scot , Oshun Jasper , Bode Colin , Dietrich William E. , Fung Inez , Dawson Todd E. 
Published: July 2013

ABSTRACTObtaining the d‐excess parameter from oxygen and hydrogen stable isotope composition of meteoric waters has the potential power to reconstruct changes in atmospheric water pools (e,g. sources, origins and overall balance) and the climatic conditions that prevail during surface evaporation. Recently, plant and ecosystem scientists turned their attention using d‐excess information to inform questions at these scales. Here, we use the d‐excess parameter to evaluate the influence of forest canopies on atmospheric humidity within a mixed evergreen forest in coastal California. We found that during the day, when transpiration was at a maximum, the d‐excess of atmospheric water vapour exceeded model predictions for the background atmosphere into which the ecosystem evapotranspiration mixes. At night when transpiration was minor, the d‐excess of atmospheric water vapour was on average less than model predictions for an ocean derived water vapour source. The observed diurnal fluctuations around the d‐excess of the modelled background water vapour provided a strong evidence that during the day as the land surface warms and the boundary layer grows plants alter the isotope composition of atmospheric humidity via non‐steady state isotope effects. In contrast, at night equilibrium isotope effects dominate as the atmosphere stabilizes. These day and nighttime fluctuations around the d‐excess of ocean derived water vapour highlight the importance of plant transpiration for the isotope hydrology of near surface humidity and subsequently for the isotope composition of condensate like dew, an important water input to this ecosystem. Copyright © 2013 John Wiley & Sons, Ltd.
An Identification Method of Magnetizing Inrush Current Phenomena by Voltage Waveform
Authors: Naitoh Tadashi , Takeda Keiki , Toyama Atsushi , Maeda Tatsuhiko 
Published: July 2013

SummaryIn this paper, the authors propose a new method for identification of magnetizing inrush current phenomena. In general, the identification is performed using the current waveform. However, saturation of current transformers makes it impossible to obtain such a waveform. Therefore, the authors introduce an identification method using the voltage waveform, in which the transformer saturation voltage does not occur. By applying Aitken's Δ2 process, it is shown that the new identification method gives accurate saturation start and end times.
A Basic Study of User Utility Maximizing Content Retrieval from Information Networks
Authors: Sugawara Shinji , Ohnishi Hiroyuki 
Published: July 2013

SummaryThis paper proposes some basic methods of content search yielding high user utility or user's satisfaction from numerous information sources scattered over large‐scale networks. In these methods, the search policy is decided by the estimated user utility gain and/or current user utility for each search action, and the most favorable combination of information sources and search content items is selected so as to enlarge the total user utility of the entire search activity. In addition, we evaluate the efficiency of the methods by computer simulations, in which we specify the network topology, user utility functions, probabilities of existence of the search content items in each information source, and so on, apply the proposed methods and other methods for comparison, and compare their aggregate utility gains as an estimation index. The proposed methods are found to achieve good performance in general and an index value about 2.45 times that of ordinary search is observed in an extreme simulation scenario. We discuss the pros and cons of the proposed methods for all the simulation scenarios.