bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unusual rheological characteristics of polypropylene/organoclay nanocomposites in continuous cooling process
Authors: Fan Xi , Wang Zhicheng , Wang Ke , Deng Hua , Chen Feng , Fu Qiang 
Published: January 2012

AbstractThe cooling process of isotactic polypropylene (iPP)/organoclay nanocomposites was followed by dynamic rheometry. Contrasting to typical linear increment of log G′ with decreasing temperature (log G′ ∝ 1/T) occurred on the melts for neat iPP and nanocomposites with small amounts of organoclay, an unusual rheological behavior was identified for composites with relative high organoclay content (≥5 wt %) as that: increasing of log G′ positively deviates to linear relation during cooling within certain high temperature region, thus yields an additional enhancement in viscoelastic properties. Furthermore, such unusual rheological phenomenon was found to be strongly impacted by initial dispersion level of organoclay, cooling rate, and construction of organoclay network. The origin of this unusual rheological phenomenon could be cautiously explained as due to the existence of unstable state of organoclay nanostructure, which could go further intercalation or exfoliation in some high temperature ranges. This might be a new rheological character and is meaningful for understanding the essentially structural behavior of polymer/layered clay nanocomposites, particularly containing mesoscopic clay network. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Metal Oxide‐Supported Platinum Overlayers as Proton‐Exchange Membrane Fuel Cell Cathodes
Authors: Tripković Vladimir , Abild‐Pedersen Frank , Studt Felix , Cerri Isotta , Nagami Tetsuo , Bligaard Thomas , Rossmeisl Jan 
Published: January 2012

AbstractWe investigated the activity and stability of n=(1, 2, 3) platinum layers supported on a number of rutile metal oxides (MO2; M=Ti, Sn, Ta, Nb, Hf and Zr). A suitable oxide support can alleviate the problem of carbon corrosion and platinum dissolution in Pt/C catalysts. Moreover, it can increase the activity of platinum if the interaction between the support and the metal is optimal. We found that both the activity and the stability depend on the number of platinum layers and, as expected, both converge toward platinum bulk values if the number of layers is increased. With use of a simple volcano curve for activity estimation, we found that the supported platinum layers could be active for the oxygen reduction reaction, with a few candidates possibly having an activity even greater than that of platinum. Furthermore, we established a correlation between stability and activity for supported platinum monolayers, which suggests that activity can be increased at the expense of stability and vice versa. Finally, the performance of the systems was evaluated against Pt(111) skins on Pt3X (X=Ni, Co, Fe, Ti, Sc and Y) alloys, which are the best catalysts known to date for the reaction.
Novel Application of Ag Nanoclusters in Fluorescent Imaging of Human Serum Proteins after Native Polyacrylamide Gel Electrophoresis (PAGE)
Authors: Wang Yanan , Zhang Jing , Huang Lingyun , He Dacheng , Ma Lin , Ouyang Jin , Jiang Fubin 
Published: January 2012

AbstractWe have developed a novel application for DNA oligonucleotide‐stabilized Ag nanoclusters in fluorescent imaging of human serum proteins after native polyacrylamide gel electrophoresis (PAGE). Oligonucleotide‐stabilized Ag nanoclusters were used as fluorescent probes for direct detection of proteins after native PAGE. Some relatively low‐abundance proteins, such as α‐1‐antichymotrypsin (ACT) and α‐2‐glycoprotein 1, zinc (ZAG) were easily detected by oligonucleotide‐stabilized Ag nanocluster‐based fluorescent imaging and identified by MS and MS/MS techniques, without the need of expensive antibodies or tedious immunoassay procedures. The pH condition for the oligonucleotide‐stabilized Ag nanocluster solution was optimized and the possible mechanism of interaction between proteins and DNA oligonucleotide‐stabilized Ag nanoclusters was analyzed. As a novel fluorescent detection method it is simple, fast, nontoxic and sensitive, and it shows great analytical potential in proteome research and in biochemistry.
Electrophilic Arene Hydroxylation and Phenol OH Oxidations Performed by an Unsymmetric μ‐η1:η1‐O2‐Peroxo Dicopper(II) Complex
Authors: Garcia‐Bosch Isaac , Ribas Xavi , Costas Miquel 
Published: January 2012

AbstractReactions of the unsymmetric dicopper(II) peroxide complex [CuII2(μ‐η1:η1‐O2)(m‐XYLN3N4)]2+ (1 O2, where m‐XYL is a heptadentate N‐based ligand), with phenolates and phenols are described. Complex 1 O2 reacts with p‐X‐PhONa (X=MeO, Cl, H, or Me) at −90 °C performing tyrosinase‐like ortho‐hydroxylation of the aromatic ring to afford the corresponding catechol products. Mechanistic studies demonstrate that reactions occur through initial reversible formation of metastable association complexes [CuII2(μ‐η1:η1‐O2)(p‐X‐PhO)(m‐XYLN3N4)]+ (1 O2⋅X‐PhO) that then undergo ortho‐hydroxylation of the aromatic ring by the peroxide moiety. Complex 1 O2 also reacts with 4‐X‐substituted phenols p‐X‐PhOH (X=MeO, Me, F, H, or Cl) and with 2,4‐di‐tert‐butylphenol at −90 °C causing rapid decay of 1 O2 and affording biphenol coupling products, which is indicative that reactions occur through formation of phenoxyl radicals that then undergo radical CC coupling. Spectroscopic UV/Vis monitoring and kinetic analysis show that reactions take place through reversible formation of ground‐state association complexes [CuII2(μ‐η1:η1‐O2)(X‐PhOH)(m‐XYLN3N4)]2+ (1 O2⋅X‐PhOH) that then evolve through an irreversible rate‐determining step. Mechanistic studies indicate that 1 O2 reacts with phenols through initial phenol binding to the Cu2O2 core, followed by a proton‐coupled electron transfer (PCET) at the rate‐determining step. Results disclosed in this work provide experimental evidence that the unsymmetric 1 O2 complex can mediate electrophilic arene hydroxylation and PCET reactions commonly associated with electrophilic Cu2O2 cores, and strongly suggest that the ability to form substrate⋅Cu2O2 association complexes may provide paths to overcome the inherent reactivity of the O2‐binding mode. This work provides experimental evidence that the presence of a H+ completely determines the fate of the association complex [CuII2(μ‐η1:η1‐O2)(X‐PhO(H))(m‐XYLN3N4)]n+ between a PCET and an arene hydroxylation reaction, and may provide clues to help understand enzymatic reactions at dicopper sites.
Synthesis of Thermo‐ and pH‐Sensitive Polyion Complex Micelles for Fluorescent Imaging
Authors: Liu Yun , Li Cao , Wang Hui‐Yuan , Zhang Xian‐Zheng , Zhuo Ren‐Xi 
Published: January 2012

AbstractTwo thermo‐ and pH‐sensitive polypeptide‐based copolymers, poly(N‐isopropylacrylamide‐co‐N‐hydroxymethylacrylamide)‐b‐poly(L‐lysine) (P(NIPAAm‐co‐HMAAm)‐b‐PLL, P1) and poly(N‐isopropylacrylamide‐co‐N‐hydroxymethylacrylamide)‐b‐poly(glutamic acid) (P(NIPAAm‐co‐HMAAm)‐b‐PGA, P2), have been designed and synthesized by the ring‐opening anionic polymerization of N‐carboxyanhydrides (NCA) with amino‐terminated P(NIPAAm‐co‐HMAAm). It was found that the block copolymers exhibit good biocompatibility and low toxicity. As a result of electrostatic interactions between the positively charged PLL and negatively charged PGA, P1 and P2 formed polyion complex (PIC) micelles consisting of polyelectrolyte complex cores and P(NIPAAm‐co‐HMAAm) shells in aqueous solution. The thermo‐ and pH‐sensitivity of the PIC micelles were studied by UV/Vis spectrophotometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Moreover, fluorescent PIC micelles were achieved by introducing two fluorescent molecules with different colors. Photographs and confocal laser scanning microscopy (CLSM) showed that the fluorescence‐labeled PIC micelles exhibit thermo‐ and pH‐dependent fluorescence, which may find wide applications in bioimaging in complicated microenvironments.
A Strategy for the High Dispersion of PtRu Nanoparticles onto Carbon Nanotubes and Their Electrocatalytic Oxidation of Methanol
Authors: Kuang Yinjie , Cui Ying , Zhang Yunsong , Yu Yaming , Zhang Xiaohua , Chen Jinhua 
Published: January 2012

AbstractCarbon nanotubes (CNTs) were non‐covalently functionalized by 1‐pyrenecarboxaldehyde (PCA) via ππ stacking interactions. PCA not only acts as the reductant for the deposition of PtRu nanoparticles, but the oxidation product of PCA can also effectively anchor and stabilize the in‐situ‐produced PtRu NPs on the surface of CNTs. Transmission electron microscopy demonstrates that PtRu NPs are uniformly dispersed on the surface of CNTs with small particles sizes of about 1.7 nm. The obtained PtRu‐NP/CNT composites have higher electrochemical surface areas, electrocatalytic activities, and better stability towards methanol oxidation compared to PtRu NPs supported on pristine CNTs.
Effect of Device Fabrication Conditions on Photovoltaic Performance of Polymer Solar Cells Based on Poly(3‐hexylthiophene) and Indene‐C70 Bisadduct
Authors: Zhao Guangjin , He Youjun , Peng Bo , Li Yongfang 
Published: January 2012

AbstractEffect of the device fabrication conditions on photovoltaic performance of the polymer solar cells based on poly(3‐hexylthiophene) (P3HT) as donor and indene‐C70 bisadduct (IC70BA) as acceptor was studied systematically. The device fabrication conditions we studied include pre‐thermal annealing temperature, active layer thickness, and the P3HT:IC70BA weight ratios. For devices with a 188‐nm‐thick active layer of P3HT:IC70BA (1:1, w:w) blend film and pre‐thermal annealing at 150°C for 10 min, maximum power conversion efficiency (PCE) reached 5.82% with Voc of 0.81 V, Isc of 11.37 mA/cm2, and FF of 64.0% under the illumination of AM1.5G, 100 mW/cm2.
β‐Alanine‐DBU: A Highly Efficient Catalytic System for Knoevenagel‐Doebner Reaction under Mild Conditions
Authors: Zhu Lingjian , Lei Ning , Miao Zhenyuan , Sheng Chunquan , Zhuang Chunlin , Yao Jianzhong , Zhang Wannian 
Published: January 2012

AbstractA mild and efficient Knoevenagel‐Doebner reaction from malonic acid and a wide range of aldehydes was catalyzed by a catalytic system consisting of β‐alanine and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), affording the corresponding (E)‐α,β‐unsaturated carboxylic acids in good to excellent yields and with high stereoselectivity. The advantage of the method is that the reaction could proceed smoothly at ambient temperature so that it can tolerate a variety of functional groups and avoid unnecessary side reactions.
A Green Route for the One‐Pot Synthesis of 1,2‐Disubstituted Benzimidazoles Using Iron(III) Phosphate under Solventless Conditions
Authors: Behbahani F. K. , Ziaei Parisa 
Published: January 2012

Abstract1,2‐Disubstituted benzimidazoles are selectively synthesized in high yields under extremely mild conditions via the condensation of o‐phenylenediamine derivatives with aldehyde derivatives using catalytic amount of iron(III) phosphate under solvent‐free conditions. The use of readily available iron(III) phosphate as a reusable and recyclable catalyst makes this process quite simple, convenient, and environment‐friendly.
Evaluation and Comparison of a 3,5‐Dimethylphenyl Isocyanate Teicoplanin with Phenyl Isocyanate Teicoplanin Chiral Stationary Phase Using RP‐HPLC
Authors: Shen Baochun , Zhang Datong , Yu Xiaoyan , Guo Wei , Han Yaqiong , Xu Xiuzhu 
Published: January 2012

AbstractHPLC enantiomeric separations of 8 α‐amino acids were achieved using two self‐made chiral stationary phases (CSP)–phenyl isocyanate teicoplanin (Phe‐TE) and 3,5‐dimethylphenyl isocyanate teicoplanin (DMP‐TE), using reversed phase mobile phases. The Phe‐TE or the DMP‐TE CSP was prepared from the TE using derivative agents, phenyl isocyanate or 3,5‐dimethylphenyl isocyanate, respectively. The chromatographic results were given as the retention, selectivity, resolution factor and the enantioselective free energy difference corresponding to the separation of the two enantiomers. The effect of pH, organic modifier type and amount were discussed, and the stereoselectivities for two TE‐based CSPs were compared. The chiral selectivity factor for six α‐amino acids on DMP‐TE is somewhat bigger than that on Phe‐TE CSP under reversed phase (RP) mode. Comparison of the enantiomeric separations using self‐made Phe‐TE and DMP‐TE was conducted to gain a better understanding of the chiral recognition mechanism of the macrocyclic glycopeptide CSP.
A Facile One‐pot Synthesis of α‐Halo,α‐allylic Aldehydes from α,α‐Dihalo Ketones Utilizing Allylic Zinc Bromide
Authors: Wang Xiaolei , Zhang Songlin 
Published: January 2012

AbstractAn efficient synthesis of various α‐halo,α‐allylic aldehydes from α,α‐dihalo ketones using both cyclic (3‐bromocyclohex‐1‐ene zinc bromide and (Z)‐3‐bromocyclobut‐1‐ene zinc bromide) and acyclic (allylzinc bromide and cinnamylzinc bromide) type of allylic organozinc bromide with DMF as base is described. A possible reaction mechanism is also proposed.
Chemical Speciation of Vanadium in Coal Bottom Ash
Authors: Aydin Firat , Saydut Abdurrahman , Gunduz Beniz , Aydin Isil , Hamamci Candan 
Published: January 2012

AbstractChemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two‐stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Speciation of vanadium was carried out using a seven‐step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg−1 d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg−1 d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg−1 d.w.) > sulfide (176 mg kg−1 d.w.) > carbonate (85 mg kg−1 d.w.) > oxidizable (50 mg kg−1 d.w.) > water soluble (10.6 mg kg−1 d.w.) > exchangeable (9.0 mg kg−1 d.w.).
The Runoff Declining Process and Water Quality in Songhuajiang River Catchment, China under Global Climatic Change
Authors: Mu Xingmin , Li Ying , Gao Peng , Shao Hongbo , Wang Fei 
Published: January 2012

AbstractThe runoff in Songhuajiang River catchment has experienced a decreasing trend during the second half of the 20th century. Serially complete daily rainfall data of 42 rainfall stations from 1959 to 2002 and daily runoff data of five meteorological stations from 1953 to 2005 were obtained. The Mann–Kendall trend test and the sequential version of Mann–Kendall test were employed in this study to test the monthly and annual trends for both rainfall and runoff, to determine the start point of abrupt runoff declining, and to identify the main driving factors of runoff decline. The results showed an insignificant increasing trend in rainfall but a significant decreasing trend in runoff in the catchment. For the five meteorological stations, abrupt runoff decline occurred during 1957–1963 and the middle 1990s. Through Mann–Kendall comparisons for the area‐rainfall and runoff for the two decreasing periods, human activity, rather than climatic change, is identified as the main driving factor of runoff decline. Analysis of land use/cover shows that farmland is most related with runoff decline among all the land use/cover change in Nenjiang catchment. From 1986 to 1995, the area of farmland increased rapidly from 6.99 to 7.61 million hm2. Hydraulic engineering has a significant influence on the runoff decline in the second Songhuajiang catchment. Many large‐scale reservoirs and hydropower stations have been built in the upstream of the Second Songhuajiang and lead to the runoff decline. Nenjiang and the Second Songhuajiang are the two sources of mainstream of Songhuajiang. Decreased runoff in these two sub‐catchments then results in runoff decrease in mainstream of Songhuajiang catchment. It is, therefore, concluded that high percent agricultural land and hydraulic engineering are the most probable driving factors of runoff decline in Songhuajiang River catchment, China.
Influence of Soil Air Permeability Change on Soil Vapour Extraction Systems Design
Authors: Boudouch Otmane , Daoud Esrael , Mariem Kacem , Benadda Belkacem 
Published: January 2012

AbstractSoil air permeability plays a decisive role in the effectiveness of soil vapour extraction (SVE) for the removal of volatile organic contaminants (VOCs) from soil. The objective of this work is to study the change of the soil air permeability during continuous venting and removal of contaminant from a polluted soil. SVE pilot experiments were conducted to investigate the interaction of soil air permeability with total liquids saturation. Oppositely to previous studies, air permeability was measured by fitting pressure data measured in a 3D laboratory venting pilot to an analytical airflow solution. The experimental correlation was compared with two different correlations published previously. A difference was observed between measured and calculated air relative air permeabilities especially for low water saturation degrees. The importance of the correct estimate of relative permeability was then illustrated by comparing vacuums and streamlines calculated using measured permeability and permeability values estimated with the two correlations tested here. Results show that an inappropriate assessment of relative permeability may engender significant errors in designing an SVE system. The second part of this work reports on the influence of air permeability change on the prediction capability of an SVE mathematical model. A significant difference between simulated breakthrough curves, estimated using firstly the relationship established experimentally and secondly the two other correlations, was observed. These results lead us to say that inadequate characterization of the air permeability change may generate significant errors in removal rate and closure time estimates.
Plant Species Richness Affected Nitrogen Retention and Ecosystem Productivity in a Full‐Scale Constructed Wetland
Authors: Zhu Si‐Xi , Zhang Peili , Wang Hai , Ge Han‐Liang , Chang Jie , Chang Scott , Qiu Zhi , Shao Hongbo , Ge Ying 
Published: January 2012

AbstractThe effects of plant species richness (SR; i.e., 1, 2, 4, 8, and 16 species per plot) on substrate nitrate and ammonium retention and ecosystem productivity in a full‐scale constructed wetland (CW) with high nitrogen (N) input were studied. Substrate nitrate (0.1–16.4 mg kg−1) and ammonium concentrations (1.3–9.2 mg kg−1) in this study were higher than those in other comparable biodiversity experiments. Substrate nitrate concentration significantly increased while ammonium concentration significantly decreased with the increase of plant SR (p = 0.008 and 0.040, respectively). The response of ecosystem productivity to increasing SR was unimodal with four species per plot achieving the greatest productivity. Transgressive overyielding, which was compared to the most productive of corresponding monocultures, did not occur in most polycultures. We conclude that substrate N retention was enhanced by plant SR even with high N input, and plant SR could be managed to improve the efficiency of N removals in CWs for wastewater treatment.
Degradation of Disperse Blue E‐4R in Aqueous Solution by Zero‐Valent Iron/Ozone
Authors: Pan Fei , Luo Yin , Fan Jing‐Jing , Liu De‐Chao , Fu Jie 
Published: January 2012

AbstractDegradation of an anthraquinone dye, disperse blue E‐4R, by zero‐valent iron (ZVI)/ozone (O3) was carried out in a series of laboratory‐scale experiments. The obtained results indicated that this method was much more effective than single ZVI or single O3 at removal of color, chemical oxygen demand, total organic carbon, and adsorbable organic halogen. The effect of several related operational parameters, including O3 dosage, zero valent iron dosage, temperature, pH value, and ZVI particle size were also discussed. Finally, we tried to decontaminate some actual samples with this method, which showed high treatment efficiency to the sample pretreated by conventional activated sludge.
Cooperative Catalysis with First‐Row Late Transition Metals (Eur. J. Inorg. Chem. 3/2012)
Authors: van der Vlugt Jarl Ivar 
Published: January 2012

AbstractThe front cover picture shows selected examples of solid‐state structures, combining a cheap metal (here copper) with smart ligands (here lutidinyl‐based PN and PNP systems), amenable to bifunctional bond activation of (small molecule) substrates and cooperative catalysis. Financial support for this work from the Netherlands' Research Council (NWO) is gratefully acknowledged. These structures are accompanied by perpetual ‚tandem‐bicycles’︁. Miss Christine Czauderna is thanked for the inspirational design. Progress and potential for the emerging field of cooperative catalysis with first‐row transition metals is outlined in the Microreview by J. I. van der Vlugt on p. 363 ff. magnified image
The effect of roasting on the chemical composition and oxidative stability of pumpkin oil
Authors: Vujasinovic Vesna , Djilas Sonja , Dimic Etelka , Basic Zorica , Radocaj Olga 
Published: January 2012

AbstractThis study is concerned with the effect of the process of roasting of naked pumpkin seeds prior to their pressing on the chemical composition and oxidative stability of the extracted oil. Ground seeds were roasted at temperatures of 90, 110, and 130°C for 30 and 60 min, according to the traditional technology of production of roasted pumpkin oil. Depending on the roasting conditions of the seeds, this treatment resulted in a significant increase of the contents of phospholipids (from 0.005 to 0.463%), total phenolic compounds (from 4.63 to 19.60 mg/kg), and total tocopherols (from 265.79 to 350.98 mg/kg) in oil. Higher contents of these minor components enhanced the oxidative stability of the oil, i.e., increased the induction period (from 4.50 to 12.93 h). However, at the same time, the applied thermal treatment generated an increase in the primary and secondary oxidation products, resulting in higher Totox values that could lower the quality of the oil.