bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of Supramolecular Chirality in the Self‐Assemblies of Lipophilic Pyrimidine Derivatives by Choice of the Amino Acid‐Based Chiral Spacer
Authors: Datta Sougata , Samanta Suman K. , Bhattacharya Santanu 
Published: June 2013

AbstractA new family of supramolecular organogelators, based on chiral amino acid derivatives of 2,4,6‐trichloro‐pyrimidine‐5‐carbaldehyde, has been synthesized. L‐alanine was incorporated as a spacer between the pyrimidine core and long hydrocarbon tails to compare the effect of chirality and hydrogen bonding to that of the achiral analogue. The role of aromatic moiety on the chiral spacer was also investigated by introducing L‐phenyl alanine moieties. The presence of intermolecular hydrogen‐bonding leading to the chiral self‐assembly was probed by concentration‐dependent FTIR and UV/Vis spectroscopies, in addition to circular dichroism (CD) studies. Temperature and concentration‐dependent CD spectroscopy ascribed to the formation of β‐sheet‐type H‐bonded networks. The morphology and the arrangements of the molecules in the freeze‐dried gels were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X‐ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the small‐angle XRD pattern reveals that this class of gelator molecules adopts a lamellar organization. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) indicate that the solid state phase behavior of these molecules is totally dependent on the choice of their amino acid spacers. Structure‐induced aggregation properties based on the H‐bonding motifs and the packing of the molecule in three dimensions leading to gelation was elucidated by rheological studies. However, viscoelasticity was shown to depend only marginally on the H‐bonding interactions; rather it depends on the packing of the gelators to a greater extent.
Preparation of Ordered Mesoporous Alumina‐Doped Titania Films with High Thermal Stability and Their Application to High‐Speed Passive‐Matrix Electrochromic Displays
Authors: Jiang Xiangfen , Bastakoti Bishnu Prasad , Weng Wu , Higuchi Tetsuya , Oveisi Hamid , Suzuki Norihiro , Chen Wei‐Jung , Huang Yu‐Tzu , Yamauchi Yusuke 
Published: June 2013

AbstractOrdered mesoporous alumina‐doped titania thin films with anatase crystalline structure were prepared by using triblock copolymer Pluronic P123 as structure‐directing agent. Uniform Al doping was realized by using aluminum isopropoxide as a dopant source which can be hydrolyzed together with titanium tetraisopropoxide. Aluminum doping into the titania framework can prevent rapid crystallization to the anatase phase, thereby drastically increasing thermal stability. With increasing Al content, the crystallization temperatures tend to increase gradually. Even when the Al content doped into the framework was increased to 15 mol %, a well‐ordered mesoporous structure was obtained, and the mesostructural ordering was still maintained after calcination at 550 °C. During the calcination process, large uniaxial shrinkage occurred along the direction perpendicular to the substrate with retention of the horizontal mesoscale periodicity, whereby vertically oriented nanopillars were formed in the film. The resulting vertical porosity was successfully exploited to fabricate a high‐speed and high‐quality passive‐matrix electrochromic display by using a leuco dye. The vertical nanospace in the films can effectively prevent drifting of the leuco dye.
Sensing Chiral Drugs by Using CdSe/ZnS Nanoparticles Capped with N‐Acetyl‐L‐Cysteine Methyl Ester
Authors: Delgado‐Pérez Teresa , Bouchet Lydia M. , de la Guardia Miguel , Galian Raquel E. , Pérez‐Prieto Julia 
Published: June 2013

AbstractChiral quantum dots (QDs), differing in their core or shell size and, consequently, in their optical properties, were synthesized by the treatment of commercially available amine‐capped quantum dots with methyl ester N‐acetyl‐L‐cysteine (CysP). Interestingly, their colloidal methanol solutions remain stable for several months. Their NMR and IR spectra were in accordance with CysP binding to the QD surface through two anchoring groups; its thiolate (strongly bound) and the carbonyl group of its ester (weaker bound) group, whereas their circular dichroism (CD) spectra showed a new broad redshifted band, suggesting that the attachment to the QD surface modified the conformational equilibrium towards conformer(s) with optical activity in this region. These QDs were sufficiently fluorescent to perform studies of the chiral recognition of drugs, in particular the aryl propionic acids (APAs) ketoprofen (KP), naproxen (NP), flurbiprofen (FP), and ibuprofen (IP). We used different drug concentration ranges, depending on the QD solubility. All the assayed drugs quenched the QD emission in a concentration‐dependent mode. Quenching fluorescence assays with the chiral QDs (CS@CysP) showed their extraordinary capacity for the chiral recognition of KP, NP, and FP, and particularly in the case of KP and FP, a remarkable positive allosteric effect was detected for the R enantiomer. By using a drug/CS@CysP molar ratio of 5000:1 and 2500:1, the changes of intensity and the sign of the CD spectrum of the drug evidenced the dissociation of the drug carboxylic group in the presence of the QD.
Self‐Assembly of Coronene Bisimides: Mechanistic Insight and Chiral Amplification
Authors: Kulkarni Chidambar , Munirathinam Rajesh , George Subi J. 
Published: June 2013

AbstractThe study of the organization of small π‐conjugated molecules is imperative to understanding and controlling its properties for various applications. Coronene bisimides (CBIs) are potential candidates for novel liquid‐crystalline materials and active n‐type semiconductor molecules in organic electronics. To understand the self‐assembly of this seldom‐studied chromophore, we have designed two derivatives of CBIs bearing chiral and achiral 3,4,5‐trialkoxyphenyl groups at the imide position, named as CBI‐GCH and CBI‐GACH, respectively. CBI‐GCH self‐assembles mainly through π‐stacking and van der Waals interactions in nonpolar methylcyclohexane to result in long 1D fibrillar stacks. The mechanism of supramolecular polymerization was probed by using chiroptical studies, which showed an isodesmic pathway for CBI‐GCH. The thermodynamic parameters that govern the self‐assembly are detailed. CBI‐GACH also shows similar self‐assembly behavior as its chiral counterpart. X‐ray diffraction studies of both molecules reveals a 2D hexagonal columnar arrangement. The coassembly of CBI‐GCH and CBI‐GACH shows chiral amplification (sergeant and soldiers experiment) with saturation at 30–50 % of the chiral derivative, which was further used to study the dynamics of the assembly. Thus, this study presents a rare report of chiral amplification in an isodesmic system.
Identification of Hck Inhibitors As Hits for the Development of Antileukemia and Anti‐HIV Agents
Authors: Tintori Cristina , Laurenzana Ilaria , La Rocca Francesco , Falchi Federico , Carraro Fabio , Ruiz Alba , Esté José A. , Kissova Miroslava , Crespan Emmanuele , Maga Giovanni , Biava Mariangela , Brullo Chiara , Schenone Silvia , Botta Maurizio 
Published: June 2013

AbstractHematopoietic cell kinase (Hck) is a member of the Src family of non‐receptor protein tyrosine kinases. High levels of Hck are associated with drug resistance in chronic myeloid leukemia. Furthermore, Hck activity has been connected with HIV‐1. Herein, structure‐based drug design efforts were aimed at identifying novel Hck inhibitors. First, an in‐house library of pyrazolo[3,4‐d]pyrimidine derivatives, which were previously shown to be dual Abl and c‐Src inhibitors, was analyzed by docking studies within the ATP binding site of Hck to select the best candidates to be tested in a cell‐free assay. Next, the same computational protocol was applied to screen a database of commercially available compounds. As a result, most of the selected compounds were found active against Hck, with Ki values ranging from 0.14 to 18.4 μM, confirming the suitability of the computational approach adopted. Furthermore, selected compounds showed an interesting antiproliferative activity profile against the human leukemia cell line KU‐812, and one compound was found to block HIV‐1 replication at sub‐toxic concentrations.
An analysis of the contact between the stent and the artery using tube hydroforming simulation
Authors: Araújo Rogério , Guimarães Tobias A. , Oliveira Sônia A.G. 
Published: June 2013

SUMMARYStents for angioplasty have been extensively used to treat coronary diseases. The aim of this study is to analyze the expansion of the stent and the contact with the artery using tube hydroforming simulation. In the simulation, the contact stress and the final shape of the artery after stent expansion process using the Stampack ®; software will be studied. A model of a commercial stent made of 316L stainless steel was modeled by using an elastic–plastic constitutive law with isotropic hardening. The artery was modeled as a cylinder and made of hyperelastic material. The stent model studied in this work presented a good performance according to the results obtained. After expansion, any region of the stent's structure with strong risk of wrinkling, thinning, or buckling was not observed. In the forming limit diagram, all points were far from the Keeler‐Goodwin diagram. Furthermore, the expanded stent model has a good conformability. In conclusion, our data show that the proposed methodology is a useful tool to check if the stent model implanted in the artery may cause restenosis after angioplasty; thus, our tests provided a reliable tool to analyze this risk. Copyright © 2013 John Wiley & Sons, Ltd.
Applying workflow as a service paradigm to application farming
Authors: Cushing Reginald , Koulouzis Spiros , Belloum Adam , Bubak Marian 
Published: June 2013

SUMMARYTask farming is often used to enable parameter sweep for exploration of large sets of initial conditions for large scale complex simulations. Such applications occur very often in life sciences. Available solutions enable to perform parameter sweep by creating multiple job submissions with different parameters. This paper presents an approach to farm workflows, employing service oriented paradigms using the WS‐VLAM workflow manager, which provides ways to create, control, and monitor workflow applications and their components. We present two service‐oriented approaches for workflow farming: task level, whereby task harness acts as services by being invoked on which task to load, and data level, where the actual task is invoked as a service with different chunks of data to process. An experimental evaluation of the presented solution is performed with a biomedical application for which 3000 simulations were required to perform a Monte Carlo study. Copyright © 2013 John Wiley & Sons, Ltd.
Stable Aqueous Solutions of Naked Titanate Nanotubes
Authors: Zennaro Lucio , Magro Massimiliano , Vianello Fabio , Rigo Adelio , Mariotto Gino , Giarola Marco , Froner Elena , Scarpa Marina 
Published: June 2013

AbstractAqueous solutions of naked nanotubes with Ti concentration up to 10 mM are obtained by hydrothermal synthesis followed by extensive ultrasound treatment. The morphology, surface characteristics, and solution behavior of the solubilized nanotubes are investigated. The time course of the solubilization process driven by ultrasound follows a first‐order kinetic law and is mediated by the competition between Na+ and H+ for surface sites. The dynamics of interaction with small cations (i.e. the sodium ion) is studied by nuclear magnetic resonance spectroscopy and is demonstrated to be a multifaced process, since Na+ is in part free to exchange between the binding sites on nanotubes and the bulk and in part is confined to slowly exchanging nanotube sites. The aqueous titanate nanotube solutions are stable for months, thus opening new perspectives for the use of this material in drug delivery and in homogeneous photocatalysis.
Effect of Non‐Specifically Adsorbed Ions on the Surface Oxidation of Pt(111)
Authors: Nakamura Masashi , Nakajima Yo , Hoshi Nagahiro , Tajiri Hiroo , Sakata Osami 
Published: June 2013

AbstractThe oxidation processes of a Pt(111) electrode in alkaline electrolytes depend on non‐specifically adsorbed ions according to in situ X‐ray diffraction and infrared spectroscopic measurements. In an aqueous solution of LiOH, an OHad adlayer is formed in the first oxidation step of the Pt(111) electrode as a result of the strong interaction between Li+ and OHad, whereas Pt oxidation proceeds without OHad formation in CsOH solution. Structural analysis by X‐ray diffraction indicates that Li+ is strongly protective against surface roughening caused by subsurface oxidation. Although Cs+ is situated near the Pt surface, the weak protective effect of Cs+ results in irreversible surface roughening due to subsurface oxidation.
Synthesis and Characterization of Gold Clusters Ligated with 1,3‐Bis(dicyclohexylphosphino)propane
Authors: Johnson Grant E. , Priest Thomas , Laskin Julia 
Published: June 2013

AbstractIn this multidisciplinary study the chemical reduction synthesis of novel gold clusters in solution was combined with high‐resolution analytical mass spectrometry (MS) to gain insight into the composition of the gold clusters and how their size, ionic charge state, and ligand substitution influences their gas‐phase fragmentation pathways. Ultrasmall cationic gold clusters ligated with 1,3‐bis(dicyclohexylphosphino)propane (dcpp) were synthesized for the first time and introduced into the gas phase using electrospray ionization (ESI). Mass‐selected cluster ions were fragmented by employing collision‐induced dissociation (CID) and the product ions were analyzed using MS. The solutions were found to contain the multiply charged cationic gold clusters Au9L43+, Au13L53+, Au6L32+, Au8L32+, and Au10L42+ (L=dcpp). The gas‐phase fragmentation pathways of these cluster ions were examined systematically by employing CID combined with MS. In addition, CID experiments were performed on related gold clusters of the same size and ionic charge state but capped with 1,3‐bis(diphenylphosphino)propane (dppp) ligands containing phenyl functional groups at the two phosphine centers instead of cyclohexane rings. It is shown that this relatively small change in the molecular substitution of the two phosphine centers in diphosphine ligands (C6H11 versus C6H5) exerts a pronounced influence on the size of the species that are preferentially formed in solution during reduction synthesis as well as the gas‐phase fragmentation channels of otherwise identical gold cluster ions. The mass spectrometry results indicate that in addition to the length of the alkyl chain between the two phosphine centers, the substituents at the phosphine centers also play a crucial role in determining the composition, size, and stability of diphosphine‐ligated gold clusters synthesized in solution.
Facile Size‐Controllable Synthesis of Colorful Quasi‐Cubic α‐Fe2O3 Materials from Nanoscale to Microscale and Their Properties Related to the Size Effect
Authors: He Shuai , Wang Guang‐Sheng , Wang Jia‐Wei , Wei Yun‐Zhao , Wu Yun , Guo Lin , Cao Mao‐Sheng 
Published: June 2013

AbstractA facile and environmentally friendly hydrothermal approach has been employed to synthesize size‐controllable quasi‐cubic α‐Fe2O3 nanocrystals by using an aqueous solution of FeCl3 without any alkaline materials and stabilizing agent. The as‐prepared products were carefully characterized and the growth mechanism is also discussed. This hydrothermal synthesis of such quasi‐cubic structures implies a simple and low‐cost route to prepare monodisperse nanomaterials on a large scale. The size‐controllable synthesis of α‐Fe2O3 is the first achieved successfully from 80 nm to 2 μm with constant structures. The synthesized α‐Fe2O3 materials have different optical properties and stabilities in water, which are caused by the change of their band‐gap energy and specific surface areas. Finally, the dielectric properties of synthesized α‐Fe2O3 cubes were also investigated, and the differences caused by the particle sizes are discussed.
A general SPICE compatible circuit model for single‐electron devices and application to bit‐error‐rate calculations
Authors: Sharifi M. J. , Jamshidnezhad K. 
Published: June 2013

ABSTRACTThe main purpose of this paper is study of the single‐electron devices (SEDs) behavior, having metal islands, in the time domain. On this basis, some new conceptions, such as division of islands in independent type and dependent type and introduction of multi‐dimensional state space for a SED, have been presented. Then, a new circuit model is introduced for SEDs in general N‐dimensional case. This model is based on the orthodox theory and the solution of the time‐dependent master equation with the capability of installation in the HSPICE software. Hence, one can simulate behavior of the compound circuits including SEDs and other circuit elements by help of this model. Another interesting characteristic of the introduced circuit model is the possibility of using it in calculation of bit error rate in single‐electron logical gates considering both the time and the temperature effects. The behavior of various SEDs in low frequencies is studied, and the results are compared with the results of SIMON, often used as a reference. Furthermore, the time‐dependent results of these devices in high frequencies are calculated and compared with the analytic results for step inputs. These comparisons indicate accuracy and validity of the model. Finally, the model is used for simulating time‐dependent behavior of some single‐electron logic gates, and their total error rate are calculated. Copyright © 2013 John Wiley & Sons, Ltd.
Reconfigurable narrowband microwave band‐pass filter
Authors: Yuceer Mehmet 
Published: June 2013

AbstractA method is proposed for the design of band‐pass filters with tunable centre frequency and bandwidth without the need for adjusting the inter‐resonator couplings. This is achieved by cascading a quasi low‐pass filter and a quasi high‐pass filter, while minimizing interaction between the filters without the need for an isolator between the filters. Simulated results are presented. Copyright © 2013 John Wiley & Sons, Ltd.
Performance evaluation of sequential spectrum handoff in cognitive radio networks: a single‐user case
Authors: Sayyadi Soheil , Nourinia Javad 
Published: June 2013

SUMMARYPowerful spectrum handover schemes enable cognitive radios to exploit transmission opportunities in primary users’ channels appropriately. In this paper, modeling and performance evaluation of sequential spectrum sensing strategy are addressed. To this end, the average number of handovers required for finding a transmission opportunity is evaluated assuming that a prior knowledge of the presence and absence probabilities of the primary users is available. Moreover, the average throughput maximization of a secondary user by optimizing its spectrum sensing time is formulated, and a set of illustrative numerical results is then presented to validate the analytical analysis.Copyright © 2013 John Wiley & Sons, Ltd.
Paracetamol Sensor Based on Molecular Imprinting by Photosensitive Polymers
Authors: Wang Xiaohong , Luo Jing , Yi Chenglin , Liu Xiaoya 
Published: June 2013

AbstractA voltammetric paracetamol sensor based on molecularly imprinted polymeric (MIP) micelles was prepared by direct electrodeposition. The MIP micelles were prepared via macromolecule self‐assembly of an amphiphilic photocrosslinkable copolymer using paracetamol as the template molecule. The resultant molecularly imprinted polymeric micelles swelled with increasing pH, and the disassociation of the micelles occurred at pH above approximately 7.4. A robust MIP film with good solvent resistance was formed on the electrode surface by anodic electrodeposition of the MIP micelles and subsequent photocrosslinking, resulting in the fabrication of a MIP electrochemical sensor for detecting paracetamol. The resultant sensor showed good response and selectivity towards paracetamol. In addition, a wide linear range from 0.01 mmol/L to 8 mmol/L and a low detection limit of 1×10−6 mol/L for paracetamol detection was demonstrated based on this sensor. The MIP sensor also showed good stability and reversibility which was applied to determine paracetamol commercial tablets.
Indirect Speciation Analysis of Thallium in Plant Extracts by Anodic Stripping Voltammetry
Authors: Pałdyna Joanna , Krasnodębska‐Ostręga Beata , Sadowska Monika , Gołębiewska Justyna 
Published: June 2013

AbstractA sensitive voltammetric method (DPASV) was developed for the determination of Tl(I) and Tl(III) in plant extracts. To limit the influence of the organic matrix on the measurements, UV irradiation and addition of Amberlite XAD‐7 resin was studied. The application of 0.5 g of the resin allowed defining thallium speciation in 10.0 mL of a solution containing 0.20 mL of Sinapis alba extract. The quantification limit of 0.5 ng mL−1 Tl(I) was found for only 10 min of preconcentration, and is low enough to allow dilution of the sample before thallium determination. The procedure was validated using the recovery study and intermethod comparison with HPLC ICP MS.
Electrochemical Aptasensor for the Determination of Ochratoxin A at the Au Electrode Modified with Ag Nanoparticles Decorated with Macrocyclic Ligand
Authors: Evtugyn Gennady , Porfireva Anna , Sitdikov Rusal , Evtugyn Vladimir , Stoikov Ivan , Antipin Igor , Hianik Tibor 
Published: June 2013

AbstractAn electrochemical aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with electropolymerized neutral red and silver nanoparticles obtained by chemical reduction with macrocyclic ligands bearing catechol fragments. Thiolated aptamers against OTA were covalently attached to silver nanoparticles via AgS bonding. The interaction with OTA induced the conformational switch of the aptamer, which caused increase of the charge transfer resistance measured by EIS in the presence of ferricyanide ions. The LOD achieved (0.05 nM) was comparable to other electrochemical aptasensors employing sophisticated assembling technique and enzyme amplification of the signal. The aptasensor was validated in spiked beer samples. The recovery of the OTA determination was found to be 66.3±14.1 % for light beer and 64.3±1.8 % for dark beer.
Volatility Discovery Across Stock Limit Order Book and Options Markets
Authors: Wang Qin 
Published: June 2013

AbstractFoucault [Journal of Financial Markets, 2, 99–134, 1999] provides a theoretical basis for how stock price volatility influences the aggressiveness of limit order traders. I investigate volatility discovery across stock limit order book and options markets using a broad panel of NYSE‐listed stocks from November 2007 to January 2008 and find strong evidence that, as predicted, the aggressiveness of the stock limit order book and option volatility trading Granger‐cause each other. Further, I find that the aggressiveness of the stock limit order book and option volatility trading are inversely related, which is both statistically and economically significant. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 34:934–956, 2014