bluuebunny/crossref_metadata_2025 huggingface dataset:
XAFS Study on the Specific Deoxidation Behavior of Iron Titanate Catalyst for the Selective Catalytic Reduction of NOx with NH3
Authors: Liu Fudong , He Hong , Xie Lijuan
Published: October 2013

The environmentally friendly catalyst iron titanate (FeTiOx) was reported to be very active for the selective catalytic reduction of NOx with NH3 (NH3‐SCR), with high N2 selectivity and H2O/SO2 durability in the medium temperature range, and the specific microstructure of iron titanate crystallites as the active phase was determined. In consideration of the probable existence of a redox cycle between Fe3+ and Fe2+ species in the NH3‐SCR reaction, the deoxidation behavior of the FeTiOx catalyst in an H2 temperature‐programmed reduction process was studied extensively by X‐ray absorption near‐edge structure (XANES) and extended X‐ray absorption fine‐structure (EXAFS) methods. Owing to the presence of an electronic inductive effect between Fe and Ti species in the unique edge‐shared Fe3+(O)2Ti4+ structure, the reducibility of Fe3+ species in the FeTiOx catalyst was greatly enhanced compared with that in pristine Fe2O3, leading to the higher oxidation ability of Fe species in FeTiOx. In the H2 temperature‐programmed reduction process, the well‐dispersed Fe3+ species in iron titanate crystallites could be totally converted into Fe2+ in the form of ilmenite FeTiO3 below 500 °C, whereas pristine Fe2O3 could only be reduced to Fe3O4 up to this temperature point. The typical NH3‐SCR reaction is usually conducted below 500 °C, and the enhanced oxidation ability of Fe3+ species in FeTiOx catalyst is responsible for its excellent catalytic NOx reduction performance at low temperatures. Based on XANES linear fitting and EXAFS curve‐fitting results, the specific deoxidation process of the FeTiOx catalyst was proposed, which can provide useful information for the characterization of the microstructure and redox ability of active sites simultaneously in mixed oxide catalysts for certain catalytic reactions.
Calcium Oxide Supported on Monoclinic Zirconia as a Highly Active Solid Base Catalyst
Authors: Frey Anne Mette , van Haasterecht Tomas , P. de Jong Krijn , Bitter Johannes Hendrik
Published: October 2013

Calcium oxide supported on ZrO2 is a highly active catalyst for base‐catalyzed reactions such as aldol‐type reactions and transesterification reactions. The role of key parameters during preparation, that is, impregnation versus precipitation, heat treatment, and metal oxide loading on the basicity and catalytic activity were investigated for CaO supported on ZrO2. An impregnation of 10 wt % CaO on monoclinic zirconia followed by heat treatment at 600 °C resulted in high activity for the self‐condensation reaction of acetone. An evaluation of a series of CaO/ZrO2 samples with different loadings showed that the activity increased for impregnated amounts per gram catalyst of 0–10 wt % CaO, and at higher loading the activity decreased as a result of a decrease in dispersion. The number of strong base sites (calculated from CO2 desorbed at temperatures higher than 625 °C) correlated with the activity. For MgO, CaO, SrO, and BaO on zirconia the catalytic activity increased as the ionic radius of the metal cation increased, suggesting the impact of base strength on catalytic performance.
Nanocomposite Graphene/Pt Electrocatalyst as Economical Counter Electrode for Dye‐Sensitized Solar Cells
Authors: Yeh Min‐Hsin , Lin Lu‐Yin , Su Jheng‐Sin , Leu Yow‐An , Vittal R. , Sun Chia‐Liang , Ho Kuo‐Chuan
Published: October 2013

Platinum is the most common electrocatalyst used as a counter electrode (CE) in dye‐sensitized solar cells (DSSCs). However, due to its high cost, Pt presents an obstacle to popularizing DSSCs in energy‐harvesting applications. Therefore, effective utilization of Pt and good understanding of the role of its composites are critical issues for developing low‐cost DSSCs with high efficiency. In this study, a graphene/Pt nanoparticles (GN/PtNPs) nanocomposite is synthesized as the catalyst for the CE of a DSSC. GN/PtNPs catalysts with various of PtNP loadings (10–60 wt %) are obtained by using a polyol reduction method, and are subsequently characterized by using X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. A solar‐to‐electricity conversion efficiency (η) of 8.79 % is achieved for a DSSC with a GN/PtNPs CE containing 20 wt% PtNPs (GN/PtNPs‐20 %); this η value is higher than those of the cells with CEs consisting of pristine GN (7.65 %) or sputtered Pt (s‐Pt, 8.58 %). Electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel polarization plots reveal that the higher η value of the cell with GN/PtNPs‐20 % is due to the higher electrocatalytic ability of the CE for the reduction of triiodide ions (I3−) and the reduced charge‐transfer resistance at the CE/electrolyte interface. The excellent electrocatalytic performance of GN/PtNPs‐20 % is attributed essentially to its high intrinsic heterogeneous rate constant for the I3− reduction reaction and partly to its high electrochemical surface area, which are quantitatively calculated by means of a rotating disk electrode system and the Koutecký–Levich equation.
Solvent‐Dependent Truxene‐Based Nanostructures
Authors: Gomez‐Esteban Sandra , Pezella Marco , Domingo Angel , Hennrich Gunther , Gómez‐Lor Berta
Published: October 2013

Three truxene derivatives functionalized with alkyl chains, either attached directly or distanced by linking phenyl or ethynyl groups, self‐assemble in solution and induce the gelation of different solvents in spite of not being endowed with groups able to establish strong directional interactions. A 1H NMR study points to face‐to‐face alternating π‐stacked motifs at the origin of nucleation. Solvents play an important role in modulating the aggregation of these derivatives giving rise to fibrous or spherical superstructures. Analysis of the influence of different solvents on the morphology of the aggregates provides a better understanding of the various stages of the hierarchical self‐assembly. The way in which alkyl chains are attached to the central core also strongly affects the self‐assembling properties and gelation ability of this series. Phenyl spacers present the highest association constants in solution and give rise to gelation in a broader range of solvents. This behavior has been rationalized by means of 1H NMR spectroscopy, X‐ray powder diffraction, SEM, and photophysical measurements. Interestingly, it was found that these compounds in the gel state exhibit unusual emission properties most likely arising from the formation of excimers, which evidences that π–π interactions also occur in the excited state.
A Systematic Study of Fluorescence‐Based Detection of Nitroexplosives and Other Aromatics in the Vapor Phase by Microporous Metal–Organic Frameworks
Authors: Pramanik Sanhita , Hu Zhichao , Zhang Xiao , Zheng Chong , Kelly Sean , Li Jing
Published: October 2013

A systematic study is conducted on four microporous metal–organic framework compounds built on similar ligands but different structures, namely [Zn3(bpdc)3(bpy)]⋅4 DMF⋅H2O (1), [Zn3(bpdc)3(2,2′dmbpy)]⋅4 DMF⋅ H2O (2), [Zn2(bpdc)2(bpe)]⋅2 DMF (3), and [Zn(bpdc)(bpe)]⋅DMF (4) (bpdc=4,4′‐biphenyldicarboxylate; bpy=4,4′‐bipyridine; 2,2′dmbpy=2,2′‐dimethyl‐4,4′bipyridine; bpe=1,2‐bis(4‐pyridyl)ethane; DMF=N,N′‐dimethylformamide) to investigate their photoluminescence properties and sensing/detection behavior upon exposure to vapors of various aromatic molecules (analytes) including nitroaromatic explosives. The results show that all four compounds are capable of detecting these molecules in the vapor phase through fluorescence quenching or enhancement. Both electrochemical measurements and theoretical calculations are performed to analyze the analyte–MOF interactions, to explain the difference in signal response by different analytes, and to understand the mechanism of fluorescence quenching or enhancement observed in these systems. Interestingly, compound 3 also shows an emission frequency shift when exposed to benzene (BZ), chlorobenzene (ClBZ), and toluene (TO), which provides an additional variable for the identification of different analytes in the same category.
Unveiling Photodeactivation Pathways for a New Iridium(III) Cyclometalated Complex
Authors: Escudero Daniel , Heuser Eike , Meier Robert J. , Schäferling Michael , Thiel Walter , Holder Elisabeth
Published: October 2013

We report the synthesis and characterization of a neutral heteroleptic IrIII complex bearing 6‐fluoro‐2‐phenylbenzo[d]thiazole as cyclometalating ligand and (Z)‐6‐(9H‐carbazol‐9‐yl)‐5‐hydroxy‐2,2‐dimethylhex‐4‐en‐3‐one as ancillary ligand. The photodeactivation mechanisms have been elucidated through extensive density functional theory (DFT) calculations. The active role of metal‐centered (3MC) triplet excited states in the nonradiative deactivation pathways is, for first time, confirmed in such complexes.
Chiral Primary‐Amine‐Catalyzed Conjugate Addition to α‐Substituted Vinyl Ketones/Aldehydes: Divergent Stereocontrol Modes on Enamine Protonation
Authors: Fu Niankai , Zhang Long , Luo Sanzhong , Cheng Jin‐Pei
Published: October 2013

Enantioselective protonation with a catalytic enamine intermediate represents a challenging, yet fundamentally important process for the synthesis of α‐chiral carbonyls. We describe herein chiral primary‐amine‐catalyzed conjugate additions of indoles to both α‐substituted acroleins and vinyl ketones. These reactions feature enamine protonation as the stereogenic step. A simple primary–tertiary vicinal diamine 1 with trifluoromethanesulfonic acid (TfOH) was found to enable both of the reactions of acroleins and vinyl ketones with good activity and high enantioselectivity. Detailed mechanistic studies reveal that these reactions are rate‐limiting in iminium formation and they all involve a uniform H2O/acid‐bridged proton transfer in the stereogenic steps but divergent stereocontrol modes for the protonation stereoselectivity. For the reactions of α‐branched acroleins, facial selections on H2O‐bridged protonation determine the enantioselectivity, which is enhanced by an OH⋅⋅⋅π interaction with indole as uncovered by DFT calculations. On the other hand, the stereoselectivity of the reactions with vinyl ketones is controlled according to the Curtin–Hammett principle in the CC bond‐formation step, which precedes a highly stereospecific enamine protonation.
A Noble‐Metal‐Free System for Photocatalytic Hydrogen Production from Water
Authors: Mejía Esteban , Luo Shu‐Ping , Karnahl Michael , Friedrich Aleksej , Tschierlei Stefanie , Surkus Annette‐Enrica , Junge Henrik , Gladiali Serafino , Lochbrunner Stefan , Beller Matthias
Published: October 2013

A series of heteroleptic copper(I) complexes with bidentate $\widehat{PP}$ and $\widehat{NN}$ chelate ligands was prepared and successfully applied as photosensitizers in the light‐driven production of hydrogen, by using [Fe3(CO)12] as a water‐reduction catalyst (WRC). These systems efficiently reduces protons from water/THF/triethylamine mixtures, in which the amine serves as a sacrificial electron donor (SR). Turnover numbers (for H) up to 1330 were obtained with these fully noble‐metal‐free systems. The new complexes were electrochemically and photophysically characterized. They exhibited a correlation between the lifetimes of the MLCT excited state and their efficiency as photosensitizers in proton‐reduction systems. Within these experiments, considerably long excited‐state lifetimes of up to 54 μs were observed. Quenching studies with the SR, in the presence and absence of the WRC, showed that intramolecular deactivation was more efficient in the former case, thus suggesting the predominance of an oxidative quenching pathway.
Preparation of Excitation‐Independent Photoluminescent Graphene Quantum Dots with Visible‐Light Excitation/Emission for Cell Imaging
Authors: Chen Shuai , Hai Xin , Xia Chang , Chen Xu‐Wei , Wang Jian‐Hua
Published: October 2013

We report the first pyrrole‐ring surface‐functionalized graphene quantum dots (p‐GQDs) prepared by a two‐step hydrothermal approach under microwave irradiation in an ammonia medium. The most distinct feature of the functionalized GQDs is that both the excitation and emission wavelengths fall into the visible‐light region. The p‐GQDs are excited by visible light at λex 490 nm (2.53 eV) to emit excitation‐independent photoluminescence at a maximum wavelength of λem 550 nm. This is thus far the longest emission wavelength reported for GQDs. Stable photoluminescence is achieved at pH 4–10 with an ionic strength of 1.2 mol L−1 KCl. These features make the p‐GQDs excellent probes for bio‐imaging and bio‐labeling, which is demonstrated by imaging live HeLa cells.
Spin‐Crossover Complex on Au(111): Structural and Electronic Differences Between Mono‐ and Multilayers
Authors: Gopakumar Thiruvancheril G. , Bernien Matthias , Naggert Holger , Matino Francesca , Hermanns Christian F. , Bannwarth Alexander , Mühlenberend Svenja , Krüger Alex , Krüger Dennis , Nickel Fabian , Walter Waldemar , Berndt Richard , Kuch Wolfgang , Tuczek Felix
Published: October 2013

Submono‐, mono‐ and multilayers of the Fe(II) spin‐crossover (SCO) complex [Fe(bpz)2(phen)] (bpz=dihydrobis(pyrazolyl)borate, phen=1,10‐phenanthroline) have beenprepared by vacuum deposition on Au(111) substrates and investigated with near edge X‐ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). As evidenced by NEXAFS, molecules of the second layer exhibit a thermal spin crossover transition, although with a more gradual characteristics than in the bulk. For mono‐ and submonolayers of [Fe(bpz)2(phen)] deposited on Au(111) substrates at room temperature both NEXAFS and STM indicate a dissociation of [Fe(bpz)2(phen)] on Au(111) into four‐coordinate complexes, [Fe(bpz)2], and phen molecules. Keeping the gold substrate at elevated temperatures ordered monolayers of intact molecules of [Fe(bpz)2(phen)] are formed which can be spin‐switched by electron‐induced excited spin‐state trapping (ELIESST).
Design and Synthesis of Lipidic Organoalkoxysilanes for the Self‐Assembly of Liposomal Nanohybrid Cerasomes with Controlled Drug Release Properties
Authors: Liang Xiaolong , Li Xiaoda , Jing Lijia , Xue Peng , Jiang Lingdong , Ren Qiushi , Dai Zhifei
Published: October 2013

This paper reports the facile design and synthesis of a series of lipidic organoalkoxysilanes with different numbers of triethoxysilane headgroups and hydrophobic alkyl chains linked by glycerol and pentaerythritol for the construction of cerasomes with regulated surface siloxane density and controlled release behavior. It was found that the number of triethoxysilane headgroups affected the properties of the cerasomes for encapsulation efficiency, drug loading capacity, and release behavior. For both water‐soluble doxorubicin (DOX) and water‐insoluble paclitaxel (PTX), the release rate from the cerasomes decreased as the number of triethoxysilane headgroups increased. The slower release rate from the cerasomes was attributed to the higher density of the siloxane network on the surface of the cerasomes, which blocks the drug release channels. In contrast to the release results with DOX, the introduction of one more hydrophobic alkyl chain into the cerasome‐forming lipid resulted in a slower release rate of PTX from the cerasomes due to the formation of a more compact cerasome bilayer. An MTT viability assay showed that all of these drug‐loaded cerasomes inhibited proliferation of the HepG2 cancer cell line. The fine tuning of the chemical structure of the cerasome‐forming lipids would foster a new strategy to precisely regulate the release rate of drugs from cerasomes.
ZnSe Etching of Zn‐Rich Cu2ZnSnSe4: An Oxidation Route for Improved Solar‐Cell Efficiency
Authors: López‐Marino Simón , Sánchez Yudania , Placidi Marcel , Fairbrother Andrew , Espindola‐Rodríguez Moisés , Fontané Xavier , Izquierdo‐Roca Víctor , López‐García Juan , Calvo‐Barrio Lorenzo , Pérez‐Rodríguez Alejandro , Saucedo Edgardo
Published: October 2013

Cu2ZnSnSe4 kesterite compounds are some of the most promising materials for low‐cost thin‐film photovoltaics. However, the synthesis of absorbers for high‐performing devices is still a complex issue. So far, the best devices rely on absorbers grown in a Zn‐rich and Cu‐poor environment. These off‐stoichiometric conditions favor the presence of a ZnSe secondary phase, which has been proved to be highly detrimental for device performance. Therefore, an effective method for the selective removal of this phase is important. Previous attempts to remove this phase by using acidic etching or highly toxic organic compounds have been reported but so far with moderate impact on device performance. Herein, a new oxidizing route to ensure efficient removal of ZnSe is presented based on treatment with a mixture of an oxidizing agent and a mineral acid followed by treatment in an aqueous Na2S solution. Three different oxidizing agents were tested: H2O2, KMnO4, and K2Cr2O7, combined with different concentrations of H2SO4. With all of these agents Se2− from the ZnSe surface phase is selectively oxidized to Se0, forming an elemental Se phase, which is removed with the subsequent etching in Na2S. Using KMnO4 in a H2SO4‐based medium, a large improvement on the conversion efficiency of the devices is observed, related to an improvement of all the optoelectronic parameters of the cells. Improvement of short‐circuit current density (Jsc) and series resistance is directly related to the selective etching of the ZnSe surface phase, which has a demonstrated current‐blocking effect. In addition, a significant improvement of open‐circuit voltage (Voc), shunt resistance (Rsh), and fill factor (FF) are attributed to a passivation effect of the kesterite absorber surface resulting from the chemical processes, an effect that likely leads to a reduction of nonradiative‐recombination states density and a subsequent improvement of the p–n junction.
Organic Chemistry of Graphene: The Diels–Alder Reaction
Authors: Denis Pablo A.
Published: October 2013

Herein, by using dispersion‐corrected density functional theory, we investigated the Diels–Alder chemistry of pristine and defective graphene. Three dienes were considered, namely 2,3‐dimethoxy‐1,3‐butadiene (DMBD), 9‐methylanthracene (9MA), and 9,10‐dimethylanthracene (910DMA). The dienophiles that were assayed were tetracyanoethylene (TCNE) and maleic anhydride (MA). When pristine graphene acted as the dienophile, we found that the cycloaddition products were 47–63 kcal mol−1 less stable than the reactants, thus making the reaction very difficult. The presence of Stone–Wales translocations, 585 double vacancies, or 555‐777 reconstructed double vacancies did not significantly improve the reactivity because the cycloaddition products were still located at higher energy than the reactants. However, for the addition of 910DMA to single vacancies, the product showed comparable stability to the separated reactants, whereas for unsaturated armchair edges the reaction was extremely favorable. With regards the reactions with dienophiles, for TCNE, the cycloaddition product was metastable. In the case of MA, we observed a reaction product that was less stable than the reactants by 50 kcal mol−1. For the reactions between graphene as a diene and the dienophiles, we found that the most‐promising defects were single vacancies and unsaturated armchair edges, because the other three defects were much‐less reactive. Thus, we conclude that the reactions with these above‐mentioned dienes may proceed on pristine or defective sheets with heating, despite being endergonic. The same statement also applies to the dienophile maleic anhydride. However, for TCNE, the reaction is only likely to occur onto single vacancies or unsaturated armchair edges. We conclude that the dienophile character of graphene is slightly stronger than its behavior as a diene.
Spiropyran Photoswitches in the Context of DNA: Synthesis and Photochromic Properties
Authors: Brieke Clara , Heckel Alexander
Published: October 2013

A new design is presented for the incorporation of spiropyran photoswitches into nucleic acids by oligonucleotide solid phase synthesis. This design enables interaction of the 6‐nitrospirobenzopyran (NitroBIPS) photoswitch with the adjacent nucleobases and leaves the photochemical properties of NitroBIPS intact. UV/Vis spectroscopy and HPLC revealed that NitroBIPS incorporated into DNA consists of up to 40 % merocyanine in its thermal equilibrium and undergoes reversible switching between the photoisomeric spiropyran (SP) and merocyanin (MC) state by alternating excitation using visible light or heat for at least fifteen switching cycles. Exchanging the chromene part of NitroBIPS on the DNA level gives access to differently substituted spiropyran derivatives allowing the screening for spiropyrans with suitable properties in a straightforward manner. Thus, by incorporating the highly hydrolysis‐stable pyrido‐spiropyran derivative PyBIPS pure light‐triggered reversible switching of a spiropyran in DNA has been realized for the first time. Therefore, this design represents a new useful platform for investigating the photochromic behavior of different spiropyran photoswitches in a nucleic acid environment and for using spiropyrans to induce light‐ or heat‐triggered changes in conformations or in fluorescence quenching properties of oligonucleotides.
A Platinum(II) Terpyridine Metallogel with an L‐Valine‐Modified Alkynyl Ligand: Interplay of Pt⋅⋅⋅Pt, π–π and Hydrogen‐Bonding Interactions
Authors: Po Charlotte , Ke Zhihai , Tam Anthony Yiu‐Yan , Chow Hak‐Fun , Yam Vivian Wing‐Wah
Published: October 2013

A series of platinum(II) terpyridine complexes with L‐valine‐modified alkynyl ligands has been synthesized. A complex with an unsubstituted terpyridine and one valine unit on the alkynyl is shown to be capable of gel formation, which is in sharp contrast to the gelation properties of the corresponding organic counterparts. Upon sol–gel transition, a drastic color change from yellow to red is observed, which is indicative of the involvement of Pt⋅⋅⋅Pt interactions. Through the concentration‐ and temperature‐dependent UV/Vis absorption, emission, circular dichroism, and 1H NMR studies, the contribution of hydrogen bonding, Pt⋅⋅⋅Pt and π–π stacking interactions as driving forces for gelation have been established, and the importance of maintaining a delicate balance between different intermolecular forces has also been illustrated.
Solution of the dynamic population balance equation describing breakage–coalescence systems in agitated vessels: The least‐squares method
Authors: Solsvik Jannike , Jakobsen Hugo A.
Published: October 2013

A variety of processes used across, for example the cosmetics, pharmaceutical and chemical industries involve two‐phase liquid–liquid interactions. The quality of liquid–liquid emulsification systems may be importantly related to the droplet size distribution. The population balance equation (PBE) can be used to describe complex processes where the accurate prediction of the dispersed phase plays a major role for the overall behaviour of the system. In recent years, the high‐order least‐squares method has been applied to approximate the solution to population balance (PB) problems. From the chemical engineering point of view, the least‐squares method is associated with complex algebra. Moreover, in previous chemical engineering publications the method has been outlined using rather compact mathematical notations. For this reason, in this study, details of the least‐squares algebra and implementation issues are revealed. The solution strategy is illustratively applied to a test problem: a liquid–liquid emulsification system with breakage and coalescence events in a stirred tank.
Improving air permeability of paper with acrylic and melamine resins
Authors: Ma Jinxia , Zhou Xiaofan , Zhang Dan , Xiao Huining
Published: October 2013

A novel approach was developed to fabricate structures with high bulk from curled cellulosic material and to eliminate the pulp loss occurring in conventional mercerising pulp processes. Cellulose fibres treated with acrylic resin and melamine resin were curled as a result of the cross‐linking and solidification of the resins. The curled fibres brought about incompact structures of cellulose fibres with high air permeability of paper. Various influencing factors were investigated to control the air permeability of the substrates, including pulp consistency, resin amount and solidification temperature. The results showed that when the pulps at 30% consistency were treated with 10% (wt. on dry fibre) resin and solidified at 140°C, the resulting paper had similar or even better air permeability than that made from the mercerised pulps.
Systematic synthesis of high surface area silica nanoparticles in the sol–gel condition by using the central composite design (CCD) method
Authors: Shekarriz Marzieh , Khadivi Ramona , Taghipoor Sohrab , Eslamian Morteza
Published: October 2013

The sol–gel method is employed for producing high surface area silica nanoparticles from a cheap precursor, that is water glass (sodium silicate). To design the experiments systematically, the response surface method (RSM) combined with the central composite design (CCD) approach is used. Four major factors including the concentration of sodium silicate solution, solution pH, reaction temperature and reaction time are identified as the major controlling parameters and the particle surface area is considered as the response or the output parameter. A total of 31 experiments are designated by the CCD. The experiments are conducted at a centre point chosen based on experience and at its vicinity to investigate how the response changes as the factors change. Nanoparticles with a surface area as high as 630 m2/g and a particle size as low as 8 nm are produced at the optimum parameters of sodium silicate concentration of 1.5 × 10−4 g/L, pH of 4, a reaction temperature of 25°C and a reaction time of 1.5 h. A regression analysis is performed on the experimental data and a correlation is obtained that may be used to predict the particle surface area and investigate the effect of varying the factors on the response. Within the range of parameters studied here, it is found that the solution pH and then the process temperature have a profound effect on the surface area and concentration and reaction time have a moderate effect. An increase of the solution pH from 4 to higher values results in a rapid drop in the particle surface area.
Ladder‐type Diindenopyrazine Based Conjugated Copolymers for Organic Solar Cells with High Open‐circuit Voltages
Authors: Chen Shanci , Tang Changquan , Yin Zhigang , Ma Yunlong , Cai Dongdong , Ganeshan Dhanavel , Zheng Qingdong
Published: October 2013

A ladder‐type diindenopyrazine (IPY) was synthesized and used as a building block for constructing conjugated copolymers. Three copolymers based on the IPY moiety were obtained via the Suzuki coupling reaction with different monomers, including 4,7‐dithien‐2‐yl‐2,1,3‐benzothiadiazole (DBT), 5,8‐dithien‐2‐yl‐2,3‐diphenylquinoxaline (DTQ), and 5,8‐dithien‐2‐yl‐2,3‐di(4‐fluorophenyl)quinoxaline (DFTQ). The obtained polymers were characterized by 1H NMR spectroscopy, UV‐Vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC). Owing to the four solubilizing alkyl chains on the IPY unit, all the three copolymers have good solubility in common solvents. These polymers have deep‐lying HOMO energy levels in the range of −5.55–−5.60 eV, and exhibit ?eld‐effect mobilities as high as 0.006 cm2·V−1·s−1. Photovoltaic applications of these polymers as light‐harvesting and hole‐conducting materials were investigated in conjunction with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM). Both conventional and inverted devices were fabricated based on these three polymers. A power conversion efficiency (PCE) of 2.53% and a high open‐circuit voltage of 1.00 V were obtained under simulated solar light AM 1.5 G (100 mW/cm2) from an inverted solar cell with an active layer containing 25 wt% ladder‐type IPY containing copolymer (PIPYDTQ) and 75 wt% PC61BM. Moreover, a high open‐circuit voltage of 1.02 V and a PCE of 2.40% were achieved from a conventional solar cell based on PIPYDTQ.
Study of K/Mn‐MgO Supported Fe Catalysts with Fe(CO)5 and Fe(NO3)3 as Precursors for CO Hydrogenation to Light Alkenes
Authors: Tang Liping , Song Chengli , Li Mengli , Yang Xiaolong , Hu Bin
Published: October 2013

Two K/Mn‐MgO supported catalysts were prepared by Fe(CO)5 and Fe(NO3)3 as precursor respectively. The obtained Fe‐K/Mn‐MgO catalysts were tested for CO hydrogenation to light alkenes and characterized by X‐ray powder diffraction (XRD), X‐ray photoelectron spectra (XPS), H2 temperature‐programmed reduction (H2‐TPR), H2, CO and CO2 temperature‐programmed desorption (H2, CO/CO2‐TPD) and transmission electron microscope (TEM). The results indicated that the catalyst with 10 wt% Fe loading prepared by Fe(CO)5 as precursor showed better performance in syngas to light alkenes than ones obtained from Fe(NO3)3 as precursor, where the CO conversion was 62.50% and the selectivity was 55.95% at 350°C, 1.5 MPa and 1000 hminus;1, respectively.
Synthesis of New Substituted 4‐Amino‐3,5‐dinitropyridine Derivatives
Authors: Ma Congming , Wang Yongbin , Hou Kehui , Liu Zuliang , Yao Qizheng
Published: October 2013

Facile synthetic routes for the preparation of some new 4‐amino‐3,5‐dinitropyridine derivatives have been revealed. Nitration of 2‐chloropyridin‐4‐amine (1) as a starting material, in an unexpected one‐step reaction, to give dinitrated derivatives, followed by nucleophilic substitution reactions with sodium azide, potassium fluoride, ammonia, methylamine, and 4‐nitroimidazol, respectively, gave substituted 4‐amino‐3,5‐dinitropyridine derivatives. Meanwhile, its azide derivative underwent a ring closure conversion into 7‐amino‐6‐nitro‐[1,2,5]oxadiazolo[3,4‐b]pyridine‐1‐oxide. It is of significance that all of the nucleophilic substitution reactions were carried out under mild conditions.
Postdischarge International Normalized Ratio Testing and Long‐term Clinical Outcomes of Patients With Heart Failure Receiving Warfarin: Findings From the ADHERE Registry Linked to Medicare Claims
Authors: Qualls Laura G. , Greiner Melissa A. , Eapen Zubin J. , Fonarow Gregg C. , Mills Roger M. , Klaskala Winslow , Hernandez Adrian F. , Curtis Lesley H.
Published: October 2013

Background

Effective warfarin thromboprophylaxis requires maintaining anticoagulation within the recommended international normalized ratio (INR) range. INR testing rates and associations between testing and outcomes are not well understood.

Hypothesis

INR testing rates after hospitalization for acute decompensated heart failure are suboptimal, and testing is associated with lower risks of mortality and adverse clinical events.

Methods

We conducted a retrospective cohort study of patients who were long‐term warfarin users and were hospitalized for heart failure, had a medical history of atrial fibrillation or valvular heart disease, and were enrolled in fee‐for‐service Medicare. INR testing was defined as ≥1 outpatient INR test within 45 days after discharge. Using Cox proportional hazards models, we examined associations between testing and all‐cause mortality, all‐cause readmission, and adverse clinical events at 1 year.

Results

Among 8558 patients, 7722 (90.2%) were tested. After 1 year, tested patients had lower all‐cause mortality (23.5% vs 32.6%; P < 0.001) and fewer myocardial infarctions (2.0% vs 3.3%; P = 0.02). These differences remained significant after multivariable adjustment with hazard ratios of 0.72 (95% confidence interval [CI]: 0.63‐0.84; P < 0.001) and 0.58 (95% CI: 0.41‐0.83; P = 0.003), respectively. Differences in all‐cause readmission, thromboembolic events, ischemic stroke, and bleeding events were not statistically significant.

Conclusions

Postdischarge outpatient INR testing in patients with heart failure complicated by atrial fibrillation or valvular heart disease was high. INR testing was associated with improved survival and fewer myocardial infarctions at 1 year but was not independently associated with other adverse clinical events.
Significance of Aortic Valve Calcification in Patients With Low‐Gradient Low‐Flow Aortic Stenosis
Authors: Aksoy Olcay , Cam Akin , Agarwal Shikhar , Ige Mobolaji , Yousefzai Rayan , Singh Dhssraj , Griffin Brian P. , Schoenhagen Paul , Kapadia Samir R. , Tuzcu Murat E.
Published: October 2013

Background

Assessment of patients with aortic stenosis (AS) and impaired left ventricular function remains challenging. Aortic valve calcium (AVC) scoring with computed tomography (CT) and fluoroscopy has been proposed as means of diagnosing and predicting outcomes in patients with severe AS.

Hypothesis

Severity of aortic valve calcification correlates with the diagnosis of true severe AS and outcomes in patients with low‐gradient low‐flow AS.

Methods

Echocardiography and CT database records from January 1, 2000 to September 26, 2009 were reviewed. Patients with aortic valve area (AVA) < 1.0 cm2 who had ejection fraction (EF) ≤ 25% and mean valvular gradient ≤ 25 mmHg with concurrent noncontrast CT scans were included. AVC was evaluated using CT and fluoroscopy. Mortality and aortic valve replacement (AVR) were established using the Social Security Death Index and medical records. The role of surgery in outcomes was evaluated.

Results

Fifty‐one patients who met the above criteria were included. Mean age was 75.1 ± 9.6 years, and 15 patients were female. Mean EF was 21% ± 4.6% with AVA of 0.7 ± 0.1 cm2. The peak and mean gradients were 35.5 ± 10.6 and 19.0 ± 5.1 mmHg, respectively. Median aortic valve calcium score was 2027 Agatston units. Mean follow‐up was 908 days. Patients with calcium scores above the median value were found to have increased mortality (P = 0.02). The benefit of surgery on survival was more pronounced in patients with higher valvular scores (P = 0.001). Fluoroscopy scoring led to similar findings, where increased AVC predicted worse outcomes (P = 0.04).

Conclusions

In patients with low‐gradient low‐flow AS, higher valvular calcium score predicts worse long‐term mortality. AVR is associated with improved survival in patients with higher valve scores.
Practical Review of Pervious Pavement Designs
Authors: Mullaney Jennifer , Lucke Terry
Published: October 2013

An international literature review was undertaken to identify the most appropriate design for a pervious paving system. The literature review revealed that information contained in design guidelines is often unclear and occasionally conflicting and this can be confusing for designers and other stormwater professionals. This literature review was to form the basis of a design for a new research study on the benefits of using pervious pavements to promote street tree health has recently commenced at the University of the Sunshine Coast in Australia. The review identified four typical pervious paving surfaces porous concrete porous asphalt, permeable inter locking concrete pavers, and concrete and plastic grid pavers. All four pavement surfaces were found to have high stormwater pollutant removal performance in a variety of conditions, with a wide range of designs. Maintenance procedures can have a significant impact on the rate of clogging of pervious pavements which can impact on the effective life span and there is conflicting and unreliable evidence to support the inclusion of a geofabric layer within pervious paving systems. This paper summarises the literature review findings and is intended as a practical resource for designers and researchers of pervious pavement systems.
SuDS Efficiency during the Start‐Up Period under Mediterranean Climatic Conditions
Authors: Perales‐Momparler Sara , Hernández‐Crespo Carmen , Vallés‐Morán Francisco , Martín Miguel , Andrés‐Doménech Ignacio , Andreu Álvarez Joaquín , Jefferies Chris
Published: October 2013

This paper presents the performance of a number of sustainable drainage systems (SuDS) in the city of Xàtiva in the Valencia Region of Spain relatively soon after their construction. The systems studied comprise two roadside swales, one detention basin receiving runoff from one of the swales and one green roof to a school. The SuDS were installed under an EU LIFE+ project intended to demonstrate their practicability, application, and behavior under Mediterranean rainfall conditions. Most of the systems installed were in new developments but the green roof was retrofitted to a school within Xàtiva, which is a dense urban area. Full flow monitoring was undertaken and spot samples were taken to give a preliminary assessment of water quality performance. The early results presented in the paper demonstrate the effectiveness of the systems under typical Mediterranean conditions, which comprise intense rainfall from September to December and little or no precipitation at other times of the year. It is concluded that SuDS can be effectively introduced in the Mediterranean region of Spain.
Water and Wastewater Treatment in Africa – Current Practices and Challenges
Authors: Wang Hongtao , Wang Tao , Zhang Bingru , Li Fengting , Toure Brahima , Omosa Isaiah Bosire , Chiramba Thomas , Abdel‐Monem Mohamed , Pradhan Mahesh
Published: October 2013

Sustainable access to safe drinking water and basic sanitation is an important part of the millennium development goals (MDGs). For most African countries, an extensive effort is needed for the last three remaining years for the achievement of the MDGs, especially in Sub‐Saharan Africa. Current practices for water and wastewater treatment in Africa are insufficient to ensure safe water and basic sanitation. To address this challenge, joint efforts are needed, including transforming to green economy, innovating technologies, improving operation and maintenance, harvesting energy, improving governance and management, promoting public participation, and establishing water quality standards.
Fate of Nutrients in Secondary Treated Municipal Wastewater during Percolation through the Soil Media
Authors: Ak Mesut , Gunduz Orhan
Published: October 2013

The fate of nutrients (phosphorous and nitrogen species) was investigated in secondary treated municipal wastewater (STMWW) during percolation through soil media by using an experimental set‐up that consists of multiple soil columns. The columns were packed with silt loam soil samples and were operated under two different wetting and drying cycles to represent the typical operational conditions in a soil aquifer treatment (SAT) system. Dissolved oxygen, oxidation–reduction potential, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen, and phosphate phosphorus concentrations were measured in samples collected from different sampling ports along the columns. Average removal values of 62.8, 67.1, and 97.1% were achieved over 75 cm of effective soil depth over 25 weeks of operation for ammonium nitrogen, total nitrogen and phosphate phosphorus, respectively. The removal performance of nutrients typically increased by soil depth and no decrease in removal performance was observed up to end of the study. Consequently, SAT system can be considered to be an effective and low cost advanced treatment method for polishing residual nutrients in a STMWW.
Recovery and Recycling of Zn(II) from Wastewater by Scenedesmus sp. MCC 26 Isolated from a Heavy Metal Contaminated Site
Authors: Sarwa Prakash , Verma Sanjay Kumar
Published: October 2013

This study evaluated the potential of Scenedesmus sp. MCC 26 as a new cost effective and efficient alternative for removing Zn(II) ions from viscose industrial effluent. Scenedesmus sp. MCC 26 (green microalgae) was isolated from a metal contaminated site and investigated for biosorption of Zn(II) from simulated viscose industrial effluent. Different biosorption parameters such as effect of pH (2–7), initial Zn(II) ion concentration (0–600 mg/L) and contact time (0–120 min) were investigated in order to optimize the process. The maximum absorption (142.85 mg/g) by the microalgal biomass was observed at pH 6 within 60 min of contact time at 28°C. Biosorption process was found to be rapid (6 mg of Zn/g biomass per min) for initial 10 min followed by a slower phase (0.6 mg of Zn/g biomass per min). The absorption data fitted well with Langmuir isotherm (qmax = 142.85 mg/g, r2 = 0.973) and Freundlich isotherm (kf = 1.447, r2 = 0.992). Treatment of Zn(II) loaded biomass with 0.1 M H2SO4 showed almost 99% recovery of zinc which can be reused in the industrial processes. After first cycle of Zn(II) removal and recovery, the same biomass was tested for its reusability in repeated cycles. The results showed that the same biomass can be used minimum for five cycles of Zn(II) absorption and recovery with similar efficiency.
The Chlamydomonas mutant pf27 reveals novel features of ciliary radial spoke assembly
Authors: Alford Lea M. , Mattheyses Alexa L. , Hunter Emily L. , Lin Huawen , Dutcher Susan K. , Sale Winfield S.
Published: October 2013

To address the mechanisms of ciliary radial spoke assembly, we took advantage of the Chlamydomonas pf27 mutant. The radial spokes that assemble in pf27 are localized to the proximal quarter of the axoneme, but otherwise are fully assembled into 20S radial spoke complexes competent to bind spokeless axonemes in vitro. Thus, pf27 is not defective in radial spoke assembly or docking to the axoneme. Rather, our results suggest that pf27 is defective in the transport of spoke complexes. During ciliary regeneration in pf27, radial spoke assembly occurs asynchronously from other axonemal components. In contrast, during ciliary regeneration in wild‐type Chlamydomonas, radial spokes and other axonemal components assemble concurrently as the axoneme grows. Complementation in temporary dikaryons between wild‐type and pf27 reveals rescue of radial spoke assembly that begins at the distal tip, allowing further assembly to proceed from tip to base of the axoneme. Notably, rescued assembly of radial spokes occurred independently of the established proximal radial spokes in pf27 axonemes in dikaryons. These results reveal that 20S radial spokes can assemble proximally in the pf27 cilium but as the cilium lengthens, spoke assembly requires transport. We postulate that PF27 encodes an adaptor or modifier protein required for radial spoke–IFT interaction. © 2013 Wiley Periodicals, Inc.
β‐actin knock‐out mouse embryonic fibroblasts show increased expression of LIM‐, CH‐, EFh‐domain containing proteins with predicted common upstream regulators
Authors: Ampe Christophe , Libbrecht Jelle , Van Troys Marleen
Published: October 2013

β‐actin depletion from mouse embryonic fibroblasts results in an altered transcriptional response rendering these cells a myofibroblast like phenotype. The proteins and upstream regulatory factors responsible for this acquired phenotype, with prominent focal adhesions and stress fibres, are unknown. Data‐mining of the changed proteome revealed that actin binding proteins associated with stress fiber or focal adhesion formation are overexpressed in the β‐actin knock‐out cells and that many of these contain CH‐, LIM‐ or EFh‐ domains. Furthermore in silico analysis predicts potential common upstream regulators that may, at least partly, coordinate the altered transcriptional response. © 2013 Wiley Periodicals, Inc.
Racial disparities in functional disability among older women with newly diagnosed nonmetastatic breast cancer
Authors: Owusu Cynthia , Schluchter Mark , Koroukian Siran M. , Mazhuvanchery Suzanne , Berger Nathan A.
Published: October 2013

BACKGROUND

This study sought to assess racial differences in functional disability among older women with nonmetastatic breast cancer.

METHODS

In this cross‐sectional study, between April 2008 and December 2012, women aged ≥ 65 years with newly diagnosed stage I through III breast cancer were recruited from ambulatory oncology clinics at an academic center. Prior to receiving any adjuvant treatment, participants completed a comprehensive geriatric assessment. The primary outcome was functional disability, defined as dependency in any basic or instrumental activity of daily living, categorized as “yes” or “no.” Logistic regression analyses were undertaken.

RESULTS

The study enrolled 190 women whose mean age was 75.0 years at diagnosis (standard deviation=7.0, range=65‐93 years). Thirty‐two percent were African American (AA), and 39% had functional disability. Controlling for age, participants with functional disability were more likely to be AA (versus non‐Hispanic white), odds ratio=4.19, 95% confidence interval=2.12‐8.27. Fifty‐nine percent of the racial difference in functional disability was explained by a higher prevalence of lower income and education among AAs. In addition, the higher prevalence of chronic medical conditions and obesity among AAs, after accounting for socioeconomic factors, further explained 40% of the black–white difference in functional disability.

CONCLUSIONS

Among older women with newly diagnosed nonmetastatic breast cancer, functional disability is highly prevalent, and AAs are disproportionately affected. Interventions to optimize the functional status of at‐risk individuals, particularly AAs, during and after cancer treatment may improve treatment tolerance and overall survival outcomes. Cancer 2013;119:3839–3846. © 2013 American Cancer Society.
Li‐Fraumeni and Li‐Fraumeni—like syndrome among children diagnosed with pediatric cancer in Southern Brazil
Authors: Giacomazzi Juliana , Selistre Simone G. , Rossi Cristina , Alemar Barbara , Santos‐Silva Patricia , Pereira Fernando S. , Netto Cristina B. , Cossio Silvia L. , Roth Daniela E. , Brunetto Algemir L. , Zagonel‐Oliveira Marcelo , Martel‐Planche Ghyslaine , Goldim Jose R. , Hainaut Pierre , Camey Suzi A. , Ashton‐Prolla Patricia
Published: October 2013

BACKGROUND

Pediatric cancers are a feature in patients with Li‐Fraumeni syndrome and its variant Li‐Fraumeni–like syndrome (LFS/LFL). To the best of the authors' knowledge, TP53 germline mutations are currently the only molecular defect known to be associated with this disease. Recently, a specific germline mutation in this gene, p.R337H, has been reported at a high prevalence in Brazil.

METHODS

The prevalence of LFS/LFL was investigated in children with cancer who were diagnosed with tumors on the LFS/LFL spectrum and in a small consecutive series of controls without cancer. The prevalence of the germline p.R337H mutation and of other germline TP53 mutations was investigated in a general group of children with cancer and exclusively in children fulfilling the clinical criteria for LFS/LFL, respectively.

RESULTS

Among the 65 children without cancer, 1.5% had a family history of LFL whereas of the 292 children with cancer, 25.3% had a family history of LFL (P < .001). Screening for the p.R337H mutation identified 11 carriers (3.7%), 9 of whom were diagnosed with adrenocortical carcinomas (ACC) and 2 of whom were diagnosed with choroid plexus carcinomas. One of the ACC probands was homozygous mutant. The Brazilian founder haplotype and loss of heterozygosity at the p.R337H locus were present in all carriers. In addition, direct sequencing of the entire TP53 coding region and gene rearrangement analysis of probands fulfilling the criteria for LFL (Eeles 2 criteria, Birch and/or Chompret criteria) and who were negative for the p.R337H mutation revealed a DNA‐binding domain pathogenic mutation, p.G245S, in 1 child.

CONCLUSIONS

TP53 p.R337H testing should be offered to Brazilian children diagnosed with ACC and choroid plexus carcinoma. A significant percentage of children with cancer in southern Brazil fulfill the criteria for LFL and should be referred for genetic risk assessment. Cancer 2013;119:4341–4349. © 2013 American Cancer Society.