bluuebunny/crossref_metadata_2025 huggingface dataset:
High abundances of oxalic, azelaic, and glyoxylic acids and methylglyoxal in the open ocean with high biological activity: Implication for secondary OA formation from isoprene
Authors: Bikkina Srinivas , Kawamura Kimitaka , Miyazaki Yuzo , Fu Pingqing
Published: May 2014

Atmospheric dicarboxylic acids (DCA) are a ubiquitous water‐soluble component of secondary organic aerosols (SOA), which can act as cloud condensation nuclei (CCN), affecting the Earth's climate. Despite the high abundances of oxalic acid and related compounds in the marine aerosols, there is no consensus on what controls their distributions over the open ocean. Marine biological productivity could play a role in the production of DCA, but there is no substantial evidence to support this hypothesis. Here we present latitudinal distributions of DCA, oxoacids and α‐dicarbonyls in the marine aerosols from the remote Pacific. Their concentrations were found several times higher in more biologically influenced aerosols (MBA) than less biologically influenced aerosols. We propose isoprene and unsaturated fatty acids as sources of DCA as inferred from significantly higher abundances of isoprene‐SOA tracers and azelaic acid in MBA. These results have implications toward the reassessment of climate forcing feedbacks of marine‐derived SOA.
Mesosphere and lower thermosphere zonal wind variations over low latitudes: Relation to local stratospheric zonal winds and global circulation anomalies
Authors: Kishore Kumar G. , Kishore Kumar K. , Singer W. , Zülicke C. , Gurubaran S. , Baumgarten G. , Ramkumar G. , Sathishkumar S. , Rapp M.
Published: May 2014

Long‐term observations from medium‐frequency and meteor radars (1993–2012) and rocket soundings (1979–1990 and 2002–2007) are used to study mesosphere and lower thermosphere (MLT) zonal wind variations in relation to the stratospheric winds over northern low latitudes. The combined data set provides a complete height profile of amplitude of semiannual oscillation (SAO) up to 100 km, with an exception around 75–80 km. The SAO signal has maxima around 50 km and 82 km and a minimum around 65 km. The MLT zonal winds show remarkable interannual variability during northern hemispheric spring equinox and much less during fall equinox. Zonal wind mesospheric spring equinox enhancements (MSEE) appear with a periodicity of 2–3 years, suggesting a modulation by the quasi‐biennial oscillation, which we identified with the strength of stratospheric westward winds. Out of 20 years of observations, the stratospheric westward winds are strong during 11 years (non‐MSEE) and weak during 9 years. Six of these 9 years show large MLT winds (MSEE), and 3 years (1999, 2004, and 2006) show small MLT winds (missing MSEE). These unexpected small winds occur in years with global circulation anomalies associated with strong sudden stratospheric warmings and an early spring transition of zonal winds. With the proposed three MSEE classes, we take into account local and global forcing factors.
De Novo Synthesis of γ,γ‐Disubstituted Butyrolactones through a Visible Light Photocatalytic Arylation–Lactonization Sequence
Authors: Guo Wei , Cheng Hong‐Gang , Chen Li‐Yan , Xuan Jun , Feng Zhu‐Jia , Chen Jia‐Rong , Lu Liang‐Qiu , Xiao Wen‐Jing
Published: May 2014

A visible light photocatalytic arylation–lactonization sequence has been developed for the synthesis of γ,γ‐disubstituted butyrolactones. This unprecedented transformation features simple experimental procedures under very mild conditions. A one‐step synthesis of isobenzofuran‐1(3H)‐one has been carried out to demonstrate the synthetic application of this reaction.

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Copper‐Catalysed Conjugate Addition of Grignard Reagents to 2‐Methylcyclopentenone and Sequential Enolate Alkylation
Authors: Calvo Beatriz C. , Madduri Ashoka V. R. , Harutyunyan Syuzanna R. , Minnaard Adriaan J.
Published: May 2014

The copper/Rev‐JosiPhos‐catalysed asymmetric conjugate addition of Grignard reagents to 2‐methylcyclopentenone (1) provides 2,3‐disubstituted cyclopentanones in high yields and enantioselectivities, and good diastereoselectivities. Reaction of thein situformed enolate with various alkylating reagents in the presence of 1,3‐dimethyltetrahydropyrimidine‐2(1H)‐one (DMPU) affords the corresponding products in a one‐pot reaction. This procedure creates two vicinal stereocentres, one of them quaternary.

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Enantioselective Construction of the Biologically Significant Dibenzo[1,4]diazepine Scaffold via Organocatalytic Asymmetric Three‐Component Reactions
Authors: Wang Yang , Tu Man‐Su , Shi Feng , Tu Shu‐Jiang
Published: May 2014

The first catalytic asymmetric construction of the biologically important dibenzo[1,4]diazepine scaffold has been established via SPINOL‐derived chiral phosphoric acid‐catalyzed three‐component reactions of aldehydes, 1,2‐phenylenediamines and cyclohexane‐1,3‐diones, which afforded structurally complex and diverse dibenzo[1,4]diazepines in high yields and good enantioselectivities (up to 98% yield, 92:8 er). This transformation also represents the first catalytic asymmetric version of this three‐component reaction and provides an easy access to structurally rigid seven‐membered chiral heterocycles.

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Synthesis of Quinazolinones from Alcohols via Laccase‐Mediated Tandem Oxidation
Authors: Heidary Marjan , Khoobi Mehdi , Ghasemi Sabrieh , Habibi Zohreh , Faramarzi Mohammad Ali
Published: May 2014

This paper describes the synthesis of quinazolinones via a tandem reaction using the laccase‐mediator system under mild conditions. The procedure involved the laccase‐catalyzed oxidation of alcohols to the corresponding aldehydes, followed by cyclocondensation with isatoic anhydride and a number of amines to afford 2,3‐dihydroquinazolin‐4(1H)‐ones, which were further oxidized to quinazolinones in useful yields. The use of an enzyme as the catalyst, O2 as an environmentally friendly oxidant, and a citrate buffer as the green solvent represents a novel and efficient approach for the one‐pot synthesis of quinazolinones.

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Synthesis of Biaryls through Aromatic CH Bond Activation: A Review of Recent Developments
Authors: Hussain Ibrar , Singh Tripti
Published: May 2014

This review describes recent progress made in the rapidly developing field of CH bond activation, in particular for syntheses of biaryls. The catalysts presented here provide convenient strategies for the direct arylation of arenes, via single or double CH bond activation, leading to inter‐, and intramolecular carbon‐carbon bond formation. The literature from mid‐2009 to December 2013 has been discussed.

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A multi‐point electrical resistance measurement system for characterization of foam drainage regime and stability
Authors: Park Chanhyuk , Hermanowicz Slawomir W.
Published: May 2014

Foam drainage regimes are significantly associated with the nature of the hydrodynamic resistance in foam structure. A multi‐point electrical resistance measurement technique has been applied for characterization of the drainage regimes and quantifying stability within standing foams. The capacity of the technique was confirmed by the estimation of macroscopic drainage rates for aqueous foams stabilized with sodium dodecyl sulfate. The drainage of sodium dodecylbenzenesulfonate, a commercial form of linear alkylbenzene sulfonate that is the most frequently used in household detergents was studied in detail by two complementary methods (forced and free drainage). The experimental data could be fitted using a power‐law with an exponent of 1/3 for forced drainage and of 1.0 for free drainage. These data indicate the following drainage behavior: mobile bubble surfaces, causing plug‐like flow within Plateau borders, thus dissipation mainly occurs inside the nodes. This research introduced an accurate method for quantifying foam stability that can be assessed by variations of real‐time measured foam heights that incorporate the evolution of the liquid content. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3143–3150, 2014
When and for whom are relative age effects important? evidence from a simple test of cardiorespiratory fitness
Authors: Veldhuizen Scott , Wade Terrance J. , Cairney John , Hay John A. , Faught Brent E.
Published: May 2014

Objectives

When individuals of different ages are combined into a single group and an ability that varies with age is measured, younger individuals are disadvantaged. This phenomenon is known as a relative age effect (RAE) and has been shown to be widespread in sport and education.

Methods

In this article, we examine RAEs in a large group of children tested repeatedly on the 20‐m shuttle run, a common test of cardiorespiratory fitness. Following up on an earlier study that measured change with age, we add a growth curve model for change in variance, which makes it possible to derive RAEs for individuals of different ages and ability levels.

Results

Results show that a 1‐year difference in age is associated with a change in performance of about 0.2 standard deviations. For 1‐year age groups, this gives rise to ranking errors of 4 percentile ranks or less. We also show, however, that these relatively small ranking errors are capable of producing large age differences within groups identified as exceptional. Depending on the level of ability required for selection, children born in the first quarter of the year can be expected to outnumber those born in the last by 1.5 times, 2 times, or more. This finding is consistent with previously reported variation in RAEs at different performance levels.

Conclusions

Results imply that RAEs are likely to be of relatively minor concern when people are graded or ranked but can produce substantial inequities and misclassifications when people with extremely high or extremely low ability levels undergo selection. Am. J. Hum. Biol. 26:476–480, 2014. © 2014 Wiley Periodicals, Inc.
Laceration injuries and infections among workers in the poultry processing and pork meatpacking industries
Authors: Kyeremateng‐Amoah Emmanuel , Nowell Jackie , Lutty Aurora , Lees Peter S.J. , Silbergeld Ellen K.
Published: May 2014

Background

Workers in poultry processing and pork meatpacking have high rates of acute injuries and chronic disease among. The presence of zoonotic pathogens in these workplaces may interact with injury.

Methods

We investigated incidence of worker injuries, lacerations, and infections reported by 10 companies from 2004 to 2009 and calculated annual incidence rates by industry and company along with temporal trends and job‐related risk factors.

Results

Average annual mean total injury rates were 6.4 per 100 workers (poultry) and 13.2 per 100 workers (pork). Average annual mean rates for lacerations were 1.8 per 100 workers (poultry) and 1.9 per 100 (pork). Sharp tools and animal products were most frequently reported as sources for lacerations. Animal products were most frequently reported as sources of infected lacerations.

Conclusions

The results indicate that these industries continue to have high injury rates. The results also suggest that zoonotic pathogens may be preventable health and safety risks. Am. J. Ind. Med. 57:669–682, 2014. © 2014 Wiley Periodicals, Inc.
Copper‐Based Metal–Organic Frameworks as Reusable Heterogeneous Catalysts for the One‐Pot Syntheses of Imidazo[1,2‐a]pyridines
Authors: Puthiaraj Pillaiyar , Ramu Andy , Pitchumani Kasi
Published: May 2014

A copper terephthalate metal–organic framework (Cu(BDC) MOF, BDC=1,4‐benzenedicarboxylate) is used as a highly efficient heterogeneous catalyst for the one‐pot, atom‐economical synthesis of imidazo[1,2‐a]pyridines that proceeds through the three‐component coupling of aldehydes, aminopyridines, and nitromethane. This heterocyclic synthesis, which uses MOFs for the first time, involves an intermolecular aza‐Michael addition with a subsequent intramolecular cyclization and uses air as an environmentally benign oxidant. This heterogeneous Cu(BDC) MOF can be reused without the loss of its activity. Its catalytic efficiency was also highlighted by comparing it with other catalytic systems that have been used for the syntheses of imidazo[1,2‐a]pyridines. This procedure not only eliminates the use of environmentally hazardous reagents but also involves mild reaction conditions.
Tumor necrosis factor reduces the amplitude of rat cortical spreading depression in vivo
Authors: Richter Frank , Lütz Wibke , Eitner Annett , Leuchtweis Johannes , Lehmenkühler Alfred , Schaible Hans‐Georg
Published: May 2014

Objective

Brain damage and ischemia often trigger cortical spreading depression (CSD), which aggravates brain damage. The proinflammatory cytokine tumor necrosis factor (TNF) is significantly upregulated during brain damage, but it is unknown whether TNF influences spreading depression in cerebral cortex in vivo. This question is important because TNF not only furthers inflammatory reactions but might also be neuroprotective. Here we tested the hypothesis that TNF affects CSD, and we explored the direction in which CSD is modified by TNF.

Methods

CSD, elicited by pressure microinjection of KCl, was recorded in anesthetized rats and mice. TNF was administered locally into a trough, providing local TNF treatment of a cortical area. For further analysis, antibodies to TNF receptor (TNFR) 1 or 2 were applied, or CSD was monitored in TNFR1 and TNFR2 knockout mice. γ‐Aminobutyric acid (GABA)A receptors were blocked by bicuculline. Immunohistochemistry localized the cortical expression of TNFR1 and TNFR2.

Results

Local application of TNF to the cortex reduced dose‐dependently the amplitude of CSD. This effect was prevented by blockade or knockout of TNFR2 but not by blockade or knockout of TNFR1. TNFR2 was localized at cortical neurons including parvalbumin‐positive inhibitory interneurons, and blockade of GABAA receptors by bicuculline prevented the reduction of CSD amplitudes by TNF.

Interpretation

We identified a functional link between TNF and CSD. TNF activates TNFR2 in cortical inhibitory interneurons. The resulting release of GABA reduces CSD amplitudes. In this manner, TNF might be neuroprotective in pathological conditions. Ann Neurol 2014;76:43–53
Acidic‐pH‐Activatable Fluorescence Probes for Visualizing Exocytosis Dynamics
Authors: Asanuma Daisuke , Takaoka Yousuke , Namiki Shigeyuki , Takikawa Kenji , Kamiya Mako , Nagano Tetsuo , Urano Yasuteru , Hirose Kenzo
Published: May 2014

Live imaging of exocytosis dynamics is crucial for a precise spatiotemporal understanding of secretion phenomena, but current approaches have serious limitations. We designed and synthesized small‐molecular fluorescent probes that were chemically optimized for sensing acidic intravesicular pH values, and established that they can be used to sensitively and reliably visualize vesicular dynamics following stimulation. This straightforward technique for the visualization of exocytosis as well as endocytosis/reacidification processes with high spatiotemporal precision is expected to be a powerful tool for investigating dynamic cellular phenomena involving changes in the pH value.
Photocaging of Carboxylic Acids: A Modular Approach
Authors: Szymański Wiktor , Velema Willem A. , Feringa Ben L.
Published: May 2014

Photocaged compounds are important tools for studying and regulating multiple processes, including biological functions. Reported herein is the use of the Passerini multicomponent reaction for modular preparation of photocaged carboxylic acids. The reaction is compatible with several functionalities and proceeds smoothly both in water and dichloromethane. The choice of aldehyde determines the wavelength used for deprotection and enables formation of orthogonally protected products. The isocyanide component can be used for introduction of reactive tags and photosensitizers, as well as for immobilization on a solid support.
Trihapto‐Koordination eines Borirens an ein einzelnes Metallatom: ein heterocyclisches Analogon des η3‐Cyclopropenylliganden
Authors: Braunschweig Holger , Dewhurst Rian D. , Radacki Krzysztof , Tate Christopher W. , Vargas Alfredo
Published: May 2014

Ein erstes Beispiel für einen einkernigen Komplex mit einem η3‐koordinierten Borirenliganden wurde durch photolytischen Transfer eines Arylborylens auf Diphenylacetylen und Abspaltung von drei CO‐Gruppen aus dem Edukt erhalten. Der η3‐Borirenkomplex enthält ein Chrom(0)‐Zentrum, das zusätzlich η6‐artig an eine Phenylgruppe koordiniert. Der Komplex wird mit 15 % Ausbeute isoliert, und außerdem fällt das Metall‐freie Boriren in 62 % Ausbeute an. Die Bindung des Chromzentrums an den Borirenring wurde mit DFT‐Methoden untersucht.
[CpRu]‐Catalyzed Carbene Insertions into Epoxides: 1,4‐Dioxene Synthesis through SN1‐Like Chemistry with Retention of Configuration
Authors: Achard Thierry , Tortoreto Cecilia , Poblador‐Bahamonde Amalia I. , Guénée Laure , Bürgi Thomas , Lacour Jérôme
Published: May 2014

Rather than lead to the usual deoxygenation pathway, metal carbenes derived from α‐diazo‐β‐ketoesters undergo three‐atom insertions into epoxides using a combination of 1,10‐phenanthroline and [CpRu(CH3CN)3][BArF] as the catalyst. Original 1,4‐dioxene motifs are obtained as single regio‐ and stereoisomers. A perfect syn stereochemistry (retention, e.r. up to 97:3) is observed for the ring opening, which behaves as an SN1‐like transformation.
Highly Selective Allylborations of Aldehydes Using α,α‐Disubstituted Allylic Pinacol Boronic Esters
Authors: Hesse Matthew J. , Essafi Stéphanie , Watson Charlotte G. , Harvey Jeremy N. , Hirst David , Willis Christine L. , Aggarwal Varinder K.
Published: May 2014

α,α‐Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti‐Z‐selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β‐borylated allylic boronic esters gave fully substituted alkenes bearing a boronic ester which underwent further cross‐coupling enabling a highly modular and stereoselective approach to the synthesis of diaryl tetrasubstituted alkenes. Computational analysis revealed the origin of the remarkable selectivity observed.
The Origin of the Selectivity and Activity of Ruthenium‐Cluster Catalysts for Fuel‐Cell Feed‐Gas Purification: A Gas‐Phase Approach
Authors: Lang Sandra M. , Bernhardt Thorsten M. , Krstić Marjan , Bonačić‐Koutecký Vlasta
Published: May 2014

Gas‐phase ruthenium clusters Run+ (n=2–6) are employed as model systems to discover the origin of the outstanding performance of supported sub‐nanometer ruthenium particles in the catalytic CO methanation reaction with relevance to the hydrogen feed‐gas purification for advanced fuel‐cell applications. Using ion‐trap mass spectrometry in conjunction with first‐principles density functional theory calculations three fundamental properties of these clusters are identified which determine the selectivity and catalytic activity: high reactivity toward CO in contrast to inertness in the reaction with CO2; promotion of cooperatively enhanced H2 coadsorption and dissociation on pre‐formed ruthenium carbonyl clusters, that is, no CO poisoning occurs; and the presence of Ru‐atom sites with a low number of metal–metal bonds, which are particularly active for H2 coadsorption and activation. Furthermore, comprehensive theoretical investigations provide mechanistic insight into the CO methanation reaction and discover a reaction route involving the formation of a formyl‐type intermediate.
Programmable and Highly Resolved In Vitro Detection of 5‐Methylcytosine by TALEs
Authors: Kubik Grzegorz , Schmidt Moritz J. , Penner Johanna E. , Summerer Daniel
Published: May 2014

Gene expression is extensively regulated by specific patterns of genomic 5‐methylcytosine (mC), but the ability to directly detect this modification at user‐defined genomic loci is limited. One reason is the lack of molecules that discriminate between mC and cytosine (C) and at the same time provide inherent, programmable sequence‐selectivity. Programmable transcription‐activator‐like effectors (TALEs) have been observed to exhibit mC‐sensitivity in vivo, but to only a limited extent in vitro. We report an mC‐detection assay based on TALE control of DNA replication that displays unexpectedly strong mC‐discrimination ability in vitro. The status and level of mC modification at single positions in oligonucleotides can be determined unambiguously by this assay, independently of the overall target sequence. Moreover, discrimination is reliably observed for positions bound by N‐terminal and central regions of TALEs. This indicates the wide scope and robustness of the approach for highly resolved mC detection and enabled the detection of a single mC in a large, eukaryotic genome.
Assessing the Brønsted Basicity of Diaminoboryl Anions: Reactivity toward Methylated Benzenes and Dihydrogen
Authors: Dettenrieder Nicole , Aramaki Yoshitaka , Wolf Benjamin M. , Maichle‐Mössmer Cäcilia , Zhao Xiaoxi , Yamashita Makoto , Nozaki Kyoko , Anwander Reiner
Published: May 2014

Treatment of toluene or p‐xylene with diaminoboryllithium results in consecutive reactions, involving boryl‐anion‐mediated deprotonation at the benzylic position followed by nucleophilic substitution at the boron center, producing benzylborane species and LiH. Diaminoboryllithium also cleaves H2 heterolytically affording diaminohydroborane and LiH, while the reaction of lithium diaminoboryl(bromo)cuprate with H2 takes place accompanied by reduction of CuI to give diaminohydroborane, LiH, and Cu0.
Towards High‐Performance Lewis Acid Organocatalysis
Authors: Ratjen Lars , van Gemmeren Manuel , Pesciaioli Fabio , List Benjamin
Published: May 2014

The combination of Lewis acid organocatalysis and internal hydrogen‐bond assistance was used to develop a new type of highly active disulfonimide catalyst. The increased Lewis acidity was documented by activity comparisons as well as theoretical investigations. Finally, the potential of the hydrogen‐bond‐assisted disulfonimide catalyst was demonstrated by its application in an enantioselective transformation.
Linear‐nonlinear dichotomy of the rheological response of particle‐filled polymers
Authors: Randall Amy M. , Robertson Christopher G.
Published: May 2014

Novel nanoparticles, polymer‐particle coupling agents, and functionalized polymers are being developed to enhance the performance of particle‐reinforced polymer systems such as advanced rubber compounds for automobile tires. Understanding the complex rheological behavior of rubber is critical to providing insights into both processability and end‐use properties. One unique aspect of the rheology of filled elastomers is that the incorporation of particles introduces a hysteretic softening (Payne effect) at small dynamic strains. This study demonstrates that this nonlinear viscoelastic behavior needs to be considered when attempting to correlate steady shear response (Mooney viscosity) to oscillatory shear measurements from test equipment such as the Rubber Process Analyzer (RPA). While a wide array of unfilled gum elastomers show good correlation between Mooney viscosity and dynamic torque from the RPA at all of the strain amplitudes used, rubber compounds containing silica and carbon black particles only exhibit good agreement between the two measures of processability when the oscillatory strain amplitude is high enough to sufficiently break up the filler network. Other features of the filler network and its influence on nonlinear rheology are considered in this investigation, including the effects of polymer–filler interactions on filler flocculation and the use of Fourier transform rheometry to illustrate the “linear‐nonlinear dichotomy” of the Payne effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40818.
Polyaniline with high crystallinity degree: Synthesis, structure, and electrochemical properties
Authors: Du Xianfeng , Xu Youlong , Xiong Lilong , Bai Yang , Zhu Jianbo , Mao Shengchun
Published: May 2014

Polyaniline (PANI) with high crystallinity degree was facilely synthesized on the surface of stainless steel net by galvanostatic method. The effect of polymerization current density on the characteristics of morphology and structure had been investigated by field emission scanning electron microscopy (FE‐SEM), Fourier transforms infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction (XRD). FE‐SEM observations disclosed that PANI was deposited as nanofibers and their diameters decreased with the polymerization current density. FTIR studies revealed that degree of oxidation increased in order PANI‐2 < PANI‐6 < PANI‐10. XPS measurements displayed that PANI polymerized at 6 mA cm−2 (PANI‐6) exhibited much higher doping level of 77.8%, which favored the conductivity. XRD analysis discovered that the obtained PANI showed high crystallinity degree in which PANI‐6 possessed highest crystallinity degree (Xcr) up to 67%. Electrochemical performances of PANI as electrode materials were studied via cyclic voltammetry. The results presented that PANI‐6 possessed greater discharge capacity and better reversibility. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40827.
Effect of reinforcement of sustainable β‐CaSiO3 nanoparticles in bio‐based epoxy resin system
Authors: Tiimob Boniface J. , Rangari Vijaya K. , Jeelani Shaik
Published: May 2014

The β‐CaSiO3 nanoparticles (NPs) were prepared using calcium carbonate from egg shells and silica as precursors. These NPs were incorporated (1–4 wt %) into bio‐based epoxy resin to fabricate nanocomposites. Thermal and mechanical tests were carried out on these composites. The results of dynamic mechanical analysis showed significant improvement in the storage modulus of 1 and 2 wt % composites. The thermomechanical analysis data revealed ∼19 and 20% of reduction in coefficient of thermal expansion for 1 wt % of CaSiO3 before and after glass transition as compared to the neat epoxy system. Thermogravimetric analysis results also showed delayed thermal degradation of the composites by significant amounts (17–35°C) for 5% of decomposition, a proportional increase in residues corresponding to the loading concentrations. The flexure tests showed significant improvements in strength (17–36%), modulus (5–33%), and toughness for 1–4 wt % of reinforcement of β‐CaSiO3 NPs. Theoretical calculations of the reinforcement effect on the flexure modulus of the composites agree well with the experimental values. The scanning electron micrograph of the fractured surfaces revealed better interfacial interactions in the composites and enhancements in crack path deflections over the neat specimen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40867.
Influence of the interfacial adhesion on the stringiness of crosslinked polyacrylic pressure‐sensitive adhesives
Authors: Ito Keiko , Shitajima Kohei , Karyu Nozomi , Fujii Syuji , Nakamura Yoshinobu , Urahama Yoshiaki
Published: May 2014

The stringiness of crosslinked polyacrylic pressure‐sensitive adhesives (PSA) was observed during 90° peeling under a constant peel rate with various adherends in order to clarify the influence of interfacial adhesion on the stringiness behavior. The crosslinked random copolymer of butyl acrylate with 5 wt % acrylic acid was used as a representative PSA. Poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(vinyl chloride) (PVC), fused quartz plates and some surface‐modified poly(ethylene terephthalate) films were used as adherends. The films were pasted on a glass plate using a cyanoacrylate adhesive. The 180° peel strength was higher in the order of PVC >> PMMA ≈ PC > other adherends. All observed stringiness was sawtooth‐shaped, but the stringiness width and length were longer in the same order. The number of sub‐branches formed at the tips of the strings was much more for the PVC, PMMA and PC adherends. Frames formed at the front end of the strings in the case of PVC adherend. Sufficient interfacial adhesion generates large internal deformation of the PSA layer. Internal deformation occurred preferentially over peeling as a result of front frame formation. The string length and the peel load required for the constant peel rate have good correlation with the peel strength. The estimation of generated inner stress in the fibrils of the strings was possible by analysis using the string length for various adherends and the stress–strain curve of pure PSA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40869.
Dual xanthan gum/poly(vinyl acetate) or alkyl‐functionalized poly(vinyl alcohol) films as models for advanced coatings
Authors: Puga Alberto V. , Garcia‐Valls Ricard , Fernández‐Prieto Susana , Smets Johan , York David
Published: May 2014

Double‐layer films, prepared by casting films of xanthan gum (XG), and subsequently poly(vinyl acetate) (PVAc) onto the former, are reported. The resulting XG/PVAc films provide high protection as coatings to a bleaching agent, 6‐(phthalimido)peroxyhexanoic acid, in liquid detergents, due to the combined roles of the outer PVAc layer as water‐barrier and the inner XG layer as water‐sink. PVAc films cast from either homogeneous solutions in acetone or aqueous dispersions were used; the stabilities exerted by the former were markedly superior. For comparison, poly(vinyl alcohol) (PVA) was also used as outer wall material, resulting in much lower protection due to its hydrophilicity. Functionalization (silylation or acetalyzation) of PVA films is also suggested as a means to decrease the surface hydrophilicity of the material. The dual hydrophilic–hydrophobic films presented herein serve as models for advanced coatings in (micro)encapsulation processes, owing to the straightforward study of their morphology and transport phenomena. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40870.
Exploiting named entities for bilingual news clustering
Authors: Montalvo Soto , Martínez Raquel , Fresno Víctor , Delgado Agustín
Published: May 2014

In this article, we present a new algorithm for clustering a bilingual collection of comparable news items in groups of specific topics. Our hypothesis is that named entities (NEs) are more informative than other features in the news when clustering fine grained topics. The algorithm does not need as input any information related to the number of clusters, and carries out the clustering only based on information regarding the shared named entities of the news items. This proposal is evaluated using different data sets and outperforms other state‐of‐the‐art algorithms, thereby proving the plausibility of the approach. In addition, because the applicability of our approach depends on the possibility of identifying equivalent named entities among the news, we propose a heuristic system to identify equivalent named entities in the same and different languages, thereby obtaining good performance.
Oligolysine‐Conjugated Zinc(II) Phthalocyanines as Efficient Photosensitizers for Antimicrobial Photodynamic Therapy
Authors: Ke Mei‐Rong , Eastel Jennifer Mary , Ngai Karry L. K. , Cheung Yuk‐Yam , Chan Paul K. S. , Hui Mamie , Ng Dennis K. P. , Lo Pui‐Chi
Published: May 2014

A series of zinc(II) phthalocyanines conjugated with an oligolysine chain (n=2, 4, and 8) were synthesized and characterized by using various spectroscopic methods. As shown by using UV/Vis and fluorescence spectroscopic methods, these compounds were nonaggregated in N,N‐dimethylformamide, and gave a weak fluorescence emission and high singlet oxygen quantum yield (ΦΔ=0.86–0.89) as a result of their di‐α‐substitution. They became slightly aggregated in water with 0.05 % Cremophor EL, but they could still generate singlet oxygen effectively. The antimicrobial photodynamic activities of these compounds were then examined against various bacterial strains, including the Gram‐positive methicillin‐sensitive Staphylococcus aureus ATCC 25923 and methicillin‐resistant Staphylococcus aureus ATCC BAA‐43, and the Gram‐negative Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853. Generally, the dyes were much more potent toward the Gram‐positive bacteria. Only 15 to 90 nM of these photosensitizers was required to induce a 4 log reduction in the cell viability of the strains. For Escherichia coli, the photocytotoxicity increased with the length of the oligolysine chain. The octalysine derivative showed the highest potency with a 4 log reduction concentration of 0.8 μM. Pseudomonas aeruginosa was most resistant to the photodynamic treatment. The potency of the tetralysine derivative toward a series of clinical strains of Staphylococcus aureus was also examined and found to be comparable with that toward the nonclinical counterparts. Moreover, the efficacy of these compounds in photodynamic inactivation of viruses was also examined. They were highly photocytotoxic against the enveloped viruses influenza A virus (H1N1) and herpes simplex virus type 1 (HSV1), but exhibited no significant cytotoxicity against the nonenveloped viruses adenovirus type 3 (Ad3) or coxsackievirus (Cox B1). The octalysine derivative also showed the highest potency with an IC50 value of 0.05 nM for the two enveloped viruses.
Photodegradable Neutral–Cationic Brush Block Copolymers for Nonviral Gene Delivery
Authors: Hu Xianglong , Li Yang , Liu Tao , Zhang Guoying , Liu Shiyong
Published: May 2014

We report on the fabrication of a photodegradable gene‐delivery vector based on PEO‐b‐P(GMA‐g‐PDMAEMA) neutral–cationic brush block copolymers that possess cationic poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) brushes for DNA compaction, poly(ethylene oxide) (PEO) as a hydrophilic block, and poly(glycidyl methacrylate) (PGMA) as the backbone. The PEO‐b‐P(GMA‐g‐PDMAEMA) copolymers were synthesized through the combination of reversible addition–fragmentation transfer (RAFT) polymerization and postmodification. A photocleavable PEO‐based macroRAFT agent was first synthesized; next, the PEO‐b‐PGMA block copolymer was prepared by RAFT polymerization of GMA; this was followed by a click reaction to introduce the RAFT initiators on the side chains of the PGMA block; then, RAFT polymerization of DMAEMA afforded the PEO‐b‐P(GMA‐g‐PDMAEMA) copolymer. The obtained neutral–cationic brush block copolymer could effectively complex plasmid DNA (pDNA) into nanoparticles at an N/P ratio (i.e., the number of nitrogen residues per DNA phosphate) of 4. Upon UV irradiation, pDNA could be released owing to cleavage of the pDNA‐binding cationic PDMAEMA side chains as well as the nitrobenzyl ester linkages at the diblock junction point. In addition, in vitro gene transfection results demonstrated that the polyplexes could be effectively internalized by cells with good transfection efficiency, and the UV irradiation protocol could considerably enhance the efficiency of gene transfection.
Involvement of intestinal permeability in the oral absorption of clarithromycin and telithromycin
Authors: Togami Kohei , Hayashi Yoshiaki , Chono Sumio , Morimoto Kazuhiro
Published: May 2014

The involvement of intestinal permeability in the oral absorption of clarithromycin (CAM), a macrolide antibiotic, and telithromycin (TEL), a ketolide antibiotic, in the presence of efflux transporters was examined. In order independently to examine the intestinal and hepatic availability, CAM and TEL (10 mg/kg) were administered orally, intraportally and intravenously to rats. The intestinal and hepatic availability was calculated from the area under the plasma concentration–time curve (AUC) after administration of CAM and TEL via different routes. The intestinal availabilities of CAM and TEL were lower than their hepatic availabilities. The intestinal availability after oral administration of CAM and TEL increased by 1.3‐ and 1.6‐fold, respectively, after concomitant oral administration of verapamil as a P‐glycoprotein (P‐gp) inhibitor. Further, anin vitrotransport experiment was performed using Caco‐2 cell monolayers as a model of intestinal epithelial cells. The apical‐to‐basolateral transport of CAM and TEL through the Caco‐2 cell monolayers was lower than their basolateral‐to‐apical transport. Verapamil and bromosulfophthalein as a multidrug resistance‐associated proteins (MRPs) inhibitor significantly increased the apical‐to‐basolateral transport of CAM and TEL. Thus, the results suggest that oral absorption of CAM and TEL is dependent on intestinal permeability that may be limited by P‐gp and MRPs on the intestinal epithelial cells. Copyright © 2014 John Wiley & Sons, Ltd.
DNA‐Scaffolded Multivalent Ligands to Modulate Cell Function
Authors: Zhang Zhiqing , Eckert Mark A. , Ali M. Monsur , Liu Linan , Kang Dong‐Ku , Chang Elizabeth , Pone Egest J. , Sender Leonard S. , Fruman David A. , Zhao Weian
Published: May 2014

We report a simple, versatile, multivalent ligand system that is capable of specifically and efficiently modulating cell‐surface receptor clustering and function. The multivalent ligand is made of a polymeric DNA scaffold decorated with biorecognition ligands (i.e., antibodies) to interrogate and modulate cell receptor signaling and function. Using CD20 clustering‐mediated apoptosis in B‐cell cancer cells as a model system, we demonstrated that our multivalent ligand is significantly more effective at inducing apoptosis of target cancer cells than its monovalent counterpart. This multivalent DNA material approach represents a new chemical biology tool to interrogate cell receptor signaling and functions and to potentially manipulate such functions for the development of therapeutics.
Long non‐coding RNAs with low expression levels in cells are enriched in secreted exosomes
Authors: Gezer Ugur , Özgür Emre , Cetinkaya Merve , Isin Mustafa , Dalay Nejat
Published: May 2014

Long non‐coding RNAs (lncRNAs) are involved in regulating chromatin modifications, gene transcription, mRNA translation, and protein function. We recently reported a high variation in the basal expression levels of a panel of lncRNAs in HeLa and MCF‐7 cells and their differential response to DNA damage induction. Here, we hypothesized that lncRNA molecules with different cellular expression may have a differential abundance in secreted exosomes, and their exosome levels would reflect cellular response to DNA damage. MALAT1, HOTAIR, lincRNA‐p21, GAS5, TUG1, CCND1‐ncRNA in exosomes secreted from cultured cells were characterized. A different expression pattern of lncRNAs in exosomes was seen compared to cells. RNA molecules with relative low expression levels (lincRNA‐p21, HOTAIR, ncRNA‐CCND1) were highly enriched in exosomes. TUG1 and GAS5 levels were moderately elevated in exosomes, whereas MALAT1—which was the most abundant molecule in cells—was present at levels comparable to its cellular levels. lincRNA‐p21 and ncRNA‐CCND1 were the main molecules; exosome levels of them best reflect the change of their cellular levels upon exposure of the cells to bleomycin‐induced DNA damage. In conclusion, we provide evidence that lncRNAs have a differential abundance in exosomes, indicating a selective loading.
A First‐Principles Study of Carbon–Oxygen Bond Scission in Multiatomic Molecules on Flat and Stepped Metal Surfaces
Authors: Zhao Yong‐Hui , Liu Jin‐Xun , Su Hai‐Yan , Sun Keju , Li Wei‐Xue
Published: May 2014

Step sites over terrace sites have been suggested to be the active sites in many catalytic reactions particularly bond breaking of diatomic molecules. Aiming to provide insight into the role of step sites in multiatomic molecules bond breaking reactions and their dependence on catalysts, we present herein a systematic first‐principles study of carbon–oxygen bond scission of diatomic CO and multiatomic HCO and CH3HCO on flat and stepped Co, Rh, and Ir surfaces. We find that multiatomic molecules exhibit distinct carbon–oxygen scission activity from diatomic molecules regardless of the metal catalysts (Co, Rh, and Ir) considered: compared to the huge enhancement of step sites for CO with a barrier 0.81–1.29 eV lower than that of flat surfaces, the role of step sites for CH3CHO is substantially weakened with a barrier 0.11–0.27 eV higher than that of flat surfaces. The reason for this is the change of adsorption configurations on flat surfaces and increase of Pauli repulsion on the congested stepped sites for the dissociation of multiatomic molecules.
Design of a Bifunctional Ir–Zr Based Metal–Organic Framework Heterogeneous Catalyst for the N‐Alkylation of Amines with Alcohols
Authors: Rasero‐Almansa A. M. , Corma A. , Iglesias M. , Sánchez F.
Published: May 2014

The direct N‐alkylation of amines with alcohols was performed with an Ir‐Zr‐based metal–organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst was recovered and reused without significant loss of activity, and only water was produced as a byproduct.
Gold(I) N‐Heterocyclic Carbene Complexes with Naphthalimide Ligands as Combined Thioredoxin Reductase Inhibitors and DNA Intercalators
Authors: Meyer Andreas , Oehninger Luciano , Geldmacher Yvonne , Alborzinia Hamed , Wölfl Stefan , Sheldrick William S. , Ott Ingo
Published: May 2014

Organometallic conjugates consisting of a gold(I) N‐heterocyclic carbene (NHC) moiety and a naphthalimide were prepared and investigated as cytotoxic agents that interact with both DNA and the disulfide reductase enzyme thioredoxin reductase (TrxR). The complexes were potent DNA intercalators related to their naphthalimide partial structure, inhibited TrxR as a consequence of the incorporation of the gold(I) moiety, and triggered efficient cytotoxic effects in MCF‐7 breast and HT‐29 colon adenocarcinoma cells. Strong effects on tumor cell metabolism were noted for the most cytotoxic complex, chlorido[1‐(3′‐(4′′‐ethylthio‐1′′,8′′‐naphthalimid‐N′′‐yl))‐propyl‐3‐methyl‐imidazol‐2‐ylidene]gold(I) (4 d). In conclusion, the conjugation of naphthalimides with gold(I) NHC moieties provided a useful strategy for the design of bioorganometallic anticancer agents with multiple modes of action.
Dinuclear Platinum Complexes Containing Planar Aromatic Ligands to Enhance Stacking Interactions with Proteins
Authors: Ma Erin S. F. , Daniel A. Gerard , Farrell Nicholas P.
Published: May 2014

In an approach to design drugs with higher affinity for π–π stacking and electrostatic interactions with targeted biomolecules, complexes of the type [{cis‐Pt(A)2(L)}2‐μ‐{trans‐1,4‐dach}](NO3)4 ((A)2=(NH3)2 or ethylenediamine (en), L=quinoline (quin) or benzothiazole (bztz), dach=trans‐1,4‐diaminocyclohexane) were synthesized. The quinoline complex, [{cis‐Pt(en)(quin)}2‐μ‐(dach)](NO3)4 (9) was synthesized from the precursor K[PtCl3(quin)] (1), while the benzothiazole complexes, [{cis‐Pt(A)2(bztz)}2‐μ‐(dach)](NO3)4 ((A)2=(NH3)2 (10) and (A)2=en (11)) were synthesized from the precursors cis‐[Pt(A)2Cl(bztz)] ((A)2=(NH3)2 (7) and (A)2=en (8)). Their interactions with N‐acetyltryptophan and a model pentapeptide (N‐Ac‐WLDSW‐OH), modeled on the pentapeptide recognition sequence (FSDLW) of p53–mdm2 interaction, were examined by fluorescence spectroscopy. The dinuclear complexes were found to be significantly stronger at quenching the fluorescence of tryptophan than their mononuclear Pt‐based analogues indicating stronger binding. Molecular modeling suggests a “sandwich” mode of binding, and the flexibility of the dinuclear motif can allow the design of more selective and stronger‐binding complexes. Based on these results a further prototype, [{Pt(en)(9‐EtGua)}2μ‐H2N(CH2)6NH2]4+, incorporating the purine 9‐ethylguanine (9‐EtG) as a stacking moiety, was prepared which showed good cytotoxicity in A2780 and OsACL tumor cell lines.
Conjugates of Cisplatin and Cyclooxygenase Inhibitors as Potent Antitumor Agents Overcoming Cisplatin Resistance
Authors: Neumann Wilma , Crews Brenda C. , Marnett Lawrence J. , Hey‐Hawkins Evamarie
Published: May 2014

Cyclooxygenase‐2 (COX‐2) is an enzyme involved in tumorigenesis, and inhibitors of the enzyme are increasingly used as adjuvant modulators in anticancer therapies due to their synergistic effects with traditional chemotherapeutics. COX‐2 is also reported to cause resistance towards antitumor agents, such as cisplatin. Here, the first covalently linked conjugates of cisplatin and COX inhibitors are reported. These conjugates exhibit concerted transport of both drugs into tumor cells and simultaneous action upon intracellular cleavage. These platinum(IV) complexes show highly increased cytotoxicity compared with cisplatin and are even able to overcome cisplatin‐related resistance of tumor cells. While the results reported show that COX‐2 inhibition is not directly responsible for the potent activities of these conjugates, they do represent useful tool compounds for the elucidation of the influence of COX inhibitors on the efficacy of antitumor agents.
Gallium(III) complexes of NOTA‐bis (phosphonate) conjugates as PET radiotracers for bone imaging
Authors: Holub Jan , Meckel Marian , Kubíček Vojtěch , Rösch Frank , Hermann Petr
Published: May 2014

Ligands with geminal bis(phosphonic acid) appended to 1,4,7‐triazacyclonone‐1,4‐diacetic acid fragment through acetamide (NOTAMBP) or methylenephosphinate (NO2APBP) spacers designed for 68Ga were prepared. GaIII complexation is much faster for ligand with methylenephosphinate spacer than that with acetamide one, in both chemical (high reactant concentrations) and radiolabeling studies with no‐carrier‐added 68Ga. For both ligands, formation of GaIII complex was slower than that with NOTA owing to the strong out‐of‐cage binding of bis(phosphonate) group. Radiolabeling was efficient and fast only above 60 °C and in a narrow acidity region (pH ~3). At higher temperature, hydrolysis of amide bond of the carboxamide‐bis(phosphonate) conjugate was observed during complexation reaction leading to Ga–NOTA complex. In vitro sorption studies confirmed effective binding of the 68Ga complexes to hydroxyapatite being comparable with that found for common bis(phosphonate) drugs such as pamindronate. Selective bone uptake was confirmed in healthy rats by biodistribution studies ex vivo and by positron emission tomography imaging in vivo. Bone uptake was very high, with SUV (standardized uptake value) of 6.19 ± 1.27 for [68Ga]NO2APBP) at 60 min p.i., which is superior to uptake of 68Ga–DOTA‐based bis(phosphonates) and [18F]NaF reported earlier (SUV of 4.63 ± 0.38 and SUV of 4.87 ± 0.32 for [68Ga]DO3APBP and [18F]NaF, respectively, at 60 min p.i.). Coincidently, accumulation in soft tissue is generally low (e.g. for kidneys SUV of 0.26 ± 0.09 for [68Ga]NO2APBP at 60 min p.i.), revealing the new 68Ga complexes as ideal tracers for noninvasive, fast and quantitative imaging of calcified tissue and for metastatic lesions using PET or PET/CT. Copyright © 2014 John Wiley & Sons, Ltd.
Emulating facial biomechanics using multivariate partial least squares surrogate models
Authors: Wu Tim , Martens Harald , Hunter Peter , Mithraratne Kumar
Published: May 2014

A detailed biomechanical model of the human face driven by a network of muscles is a useful tool in relating the muscle activities to facial deformations. However, lengthy computational times often hinder its applications in practical settings. The objective of this study is to replace precise but computationally demanding biomechanical model by a much faster multivariate meta‐model (surrogate model), such that a significant speedup (to real‐time interactive speed) can be achieved. Using a multilevel fractional factorial design, the parameter space of the biomechanical system was probed from a set of sample points chosen to satisfy maximal rank optimality and volume filling. The input–output relationship at these sampled points was then statistically emulated using linear and nonlinear, cross‐validated, partial least squares regression models. It was demonstrated that these surrogate models can mimic facial biomechanics efficiently and reliably in real‐time. Copyright © 2014 John Wiley & Sons, Ltd.