bluuebunny/crossref_metadata_2025_split huggingface dataset:
AgBr Nanocrystals from Plates to Cubes and Their Photocatalytic Properties
Authors: Wang Hua , Liu Yang , Hu Pengfei , He Liang , Li Jinghong , Guo Lin 
Published: February 2013

AbstractAgBr nanocrystals, evolving from plates through truncated cubes and finally to regular cubes, corresponding to a progressive shrinkage of exposed {1 1 1} facets and enlargement of exposed {1 0 0} facets, were successfully prepared by facile ion‐exchange reactions under the synergistic effects of polyvinylpyrrolidone and NH3⋅ H2O. An investigation of the growth mechanism revealed that polyvinylpyrrolidone can selectively adsorb on the {1 1 1} facets of AgBr nanocrystals, whereas NH3⋅H2O not only forms a [Ag(NH3)2]+ complex that slows the rates of ion‐exchange reactions, but may also prefer to adsorb on {1 0 0} facets. Studies of their photocatalytic properties showed that the as‐prepared AgBr nanocrystals exhibited facet‐dependent photocatalytic properties. The {1 1 1}‐dominated AgBr nanoplates exhibited the highest photocatalytic activities, and the photodegradation rate of methyl orange dyes over them was 3 times faster than over AgBr nanocubes that expose {1 0 0} facets. Surface atomic models and DFT calculations indicate that the {1 1 1} facets have more dangling bonds and a higher surface energy than the {1 0 0} facets, which substantiate the facet‐dependent photocatalytic properties. Therefore, our work not only provides a novel method to prepare regular AgBr nanocrystals, but also demonstrates that the shape and exposed facets have important influence on their photocatalytic activities.
Proton Shuttle Mechanism in the Transition State of Lipase‐Catalyzed N‐Acylation of Amino Alcohols
Authors: Syrén Per‐Olof , Le Joubioux Florian , Ben Henda Yesmine , Maugard Thierry , Hult Karl , Graber Marianne 
Published: February 2013

AbstractAn increased reaction rate for lipase‐catalyzed N‐acylation of amino alcohols relative to that of monofunctionalized amines can be explained by a hydrogen shuttling mechanism that avoids nitrogen inversion in the transition state. The mechanism does not involve acyl migration from an ester intermediate that would be formed first, an explanation that permeates the literature. Our suggested reaction mechanism is dependent on the preference of amino alcohols to form intramolecular hydrogen bonds and the capability of the enzyme to accommodate and exploit the specific hydrogen bonding pattern provided by the ligand during catalysis. Our proposed proton shuttle mechanism involves the transfer of two protons in the transition state concomitant with a nucleophilic attack on the acyl enzyme and provides an explanation for the high reaction rate and chemoselectivity for lipase‐catalyzed N‐acylation of amino alcohols. Moreover, the proton shuttle mechanism explains the increased reaction rate for the enzyme‐catalyzed N‐acylation of diamines and of methoxy‐2‐propylamine, for which O‐ to N‐acyl migration is impossible. A linear free‐energy relationship analysis based on the experimental results showed that all of our investigated difunctionalized amine substrates afforded a substrate‐assisted rate acceleration of the N‐acylation by the same reaction mechanism. Furthermore, the results of the analysis were consistent with partial proton transfer in the rate‐limiting transition state, which further supports our suggested proton shuttle mechanism.
Enhancing Photoactivity of TiO2(B)/Anatase Core–Shell Nanofibers by Selectively Doping Cerium Ions into the TiO2(B) Core
Authors: Yang Dongjiang , Zhao Jian , Liu Hongwei , Zheng Zhanfeng , Adebajo Moses O. , Wang Hongxia , Liu Xiaotang , Zhang Hongjie , Zhao Jin‐cai , Bell John , Zhu Huaiyong 
Published: February 2013

AbstractCerium ions (Ce3+) can be selectively doped into the TiO2(B) core of TiO2(B)/anatase core–shell nanofibers by means of a simple one‐pot hydrothermal treatment of a starting material of hydrogen trititanate (H2Ti3O7) nanofibers. These Ce3+ ions (≈0.202 nm) are located on the (110) lattice planes of the TiO2(B) core in tunnels (width≈0.297 nm). The introduction of Ce3+ ions reduces the defects of the TiO2(B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce3+/Ce4+ couple (E°(Ce3+/Ce4+)=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO2(B). Therefore, once the Ce3+‐doped nanofibers are irradiated by UV light, the doped Ce3+ ions—in close vicinity to the interface between the TiO2(B) core and anatase nanoshell—can efficiently trap the photogenerated holes. This facilitates the migration of holes from the anatase shell and leaves more photogenerated electrons in the anatase nanoshell, which results in a highly efficient separation of photogenerated charges in the anatase nanoshell. Hence, this enhanced charge‐separation mechanism accelerates dye degradation and alcohol oxidation processes. The one‐pot treatment doping strategy is also used to selectively dope other metal ions with variable oxidation states such as Co2+/3+ and Cu+/2+ ions. The doping substantially improves the photocatalytic activity of the mixed‐phase nanofibers. In contrast, the doping of ions with an invariable oxidation state, such as Zn2+, Ca2+, or Mg2+, does not enhance the photoactivity of the mixed‐phase nanofibers as the ions could not trap the photogenerated holes.
Design of Stable β‐Sheet‐Based Cyclic Peptide Assemblies Assisted by Metal Coordination: Selective Homo‐ and Heterodimer Formation
Authors: Panciera Michele , Amorín Manuel , Castedo Luis , Granja Juan R. 
Published: February 2013

AbstractMetal‐directed supramolecular construction represents one of the most powerful tools to prepare a large variety of structures and functions. The ability of metals to organize different numbers and types of ligands with a variety of geometries (linear, trigonal, octahedral, etc.) expands the supramolecular synthetic architecture. We describe here the precise construction of homo‐ and heterodimeric cyclic peptide entities through coordination of a metal (Pd, Au) and to β‐sheet‐type hydrogen‐bonding interactions. The selective coordination properties of the appropriate metal allow control over the cross‐strand interaction between the two‐peptide strands.
Aqueous‐Phase Synthesis of Single‐Crystal Pd Seeds 3 nm in Diameter and Their Use for the Growth of Pd Nanocrystals with Different Shapes
Authors: Zhu Cun , Zeng Jie , Lu Ping , Liu Jingyue , Gu Zhongze , Xia Younan 
Published: February 2013

AbstractThis article describes an aqueous method for the synthesis of Pd seeds with a single‐crystal structure and a uniform diameter of 3 nm and their use for the growth of Pd nanocrystals with a variety of shapes. We have also investigated the effects of a number of parameters, including the temperature, reducing power of the reductant, and capping agent on the reduction rate of a Pd precursor, and thus the final size, size distribution, and morphology of the Pd seeds. By taking advantage of the coordination effect of Br− ions with Pd2+ ions and their selective adsorption on the Pd(100) surface, Pd nanocrystals with a number of distinct shapes could be conveniently produced by varying the concentration of KBr added into the growth solution. This work provides a general and facile method for the green synthesis of Pd nanocrystals with controlled shapes, especially for the preparation of Pd nanocrystals with sizes in the sub‐10 nm regime.
Asararenes—A Family of Large Aromatic Macrocycles
Authors: Schneebeli Severin T. , Cheng Chuyang , Hartlieb Karel J. , Strutt Nathan L. , Sarjeant Amy A. , Stern Charlotte L. , Stoddart J. Fraser 
Published: February 2013

AbstractWe announce the establishment of a new family of macrocycles—the asararenes, which are based on para‐methylene linked “asarol methyl ether” (1,2,4,5‐tetramethoxybenzene) units. Macrocycles with 6–12 aromatic units have been synthesized and isolated in a single step from asarol methyl ether and paraformaldehyde. Even larger rings, with up to 15 asarol methyl ether units, have been observed by high‐resolution mass spectrometry. Single‐crystal X‐ray structures of asar[6]‐, asar[7]‐, asar[8]‐, asar[9]‐, asar[10]‐ and asar[11]arene highlight the diverse structural features of this family of macrocycles. While the cavities of the asar[6–8]arene macrocycles are mostly filled with methoxyl groups, the asar[9]‐ and asar[10]arene rings contain accessible cavities and self‐assemble into infinite channels filled with solvent molecules in the solid state. These solid‐state structures highlight the potential of this family of macrocycles for a wide range of potential applications.
Theoretical Insights into the Nature of Halogen Bonding in Prereactive Complexes
Authors: Hill J. Grant , Hu Xiaojun 
Published: February 2013

AbstractBenchmark quality geometries and interaction energies for the prereactive halogen‐bonded complexes of dihalogens and ammonia, including hypothetical astatine containing dihalogens, have been produced via explicitly correlated coupled cluster methods. The application of local electron correlation partitioning reveals dispersion, electrostatics and ionic substitutions all contribute significantly to the interaction energy, with a linear relationship between the ionic substitutions and the degree of charge transfer. Potential energy curves for H3N⋅⋅⋅ClF show that as the relative orientations of the two subunits are manipulated appreciable interactions can be found at considerably angular displaced geometries, signifying lower directionality in halogen bonding than previously supposed.
Enhancement of Carbon Dioxide Capture by Amine‐Functionalized Multi‐Walled Carbon Nanotube
Authors: Khalili Soodabeh , Ghoreyshi Ali Asghar , Jahanshahi Mohsen , Pirzadeh Kasra 
Published: February 2013

AbstractIn this study, crude multi‐walled carbon nanotubes (MWCNT) was functionalized by a two‐step process; first using strong mixed acids (H2SO4/HNO3) and then treatment with 1,3‐phenylenediamine (mPDA). The equilibrium adsorption of CO2 on pristine MWCNT and amine functionalized MWCNT (MWCNT‐NH2) were investigated. Experiments were preformed via application of volumetric method in a dual sorption vessel at temperature range of 298–318 K and pressures up to 40 bars. The results obtained indicated that the equilibrium uptake of CO2 increased after functionalizing of MWCNT. The increase in CO2 capture by MWCNT‐NH2 was attributed to the existence of great affinity between CO2 molecules and amine sites on this adsorbent at low pressures. The experimental data were analyzed by means of Freundlich and Langmuir adsorption isotherm models. The data obtained revealed a fast kinetics for the adsorption of CO2 in which most of adsorption occurred at initial period of adsorption experiments. This renders MWCNT as a suitable adsorbent for practical applications. Values of isosteric heat of adsorption were evaluated based on Clausius–Clapeyron equation. The results demonstrated that both chemisorption and physisorption played important role in CO2 adsorption on MWCNT‐NH2, whereas the physisorption process was dominant for CO2 adsorption on MWCNT.
Direct Fluorination of Cyclic Carbonates and closo‐K2[B12H12] in a Slug‐Flow Ministructured Reactor
Authors: Hill Mathias , Baron Patrick , Cobry Keith , Goll Sascha K. , Lang Philipp , Knapp Carsten , Scherer Harald , Woias Peter , Zhang Pengcheng , Krossing Ingo 
Published: February 2013

AbstractA novel minireactor for direct fluorination of organic and inorganic substances was tested. The reactor consists of nickel‐coated copper blocks with mechanically machined 1 mm channels and is equipped with an active cooling system. The direct fluorination of ethylene carbonate and propylene carbonate is described. For the fluorinated propylene carbonate, the NMR data of various fluorinated isomers were determined. The Gibbs reaction energies for the direct fluorination of ethylene and propylene carbonate were calculated at the reliable G3 level of theory. The excellent decomposition stability of the cyclic carbonates against high fluorine and HF concentrations also qualifies them as good solvents for direct fluorination processes, especially for ionic substrates. In this respect, the direct fluorination of the inorganic salt closo‐K2[B12H12] in cyclic carbonates is presented.
BaSnO3 Perovskite Nanoparticles for High Efficiency Dye‐Sensitized Solar Cells
Authors: Kim Dong Wook , Shin Seong Sik , Lee Sangwook , Cho In Sun , Kim Dong Hoe , Lee Chan Woo , Jung Hyun Suk , Hong Kug Sun 
Published: February 2013

AbstractThe synthesis of highly crystalline perovskite BaSnO3 nanoparticles for use as photoanode materials in dye‐sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO3 nanoparticles (BaSnO3 cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO3 film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide‐based DSSCs. More importantly, the BaSnO3 cells show superior charge collection in nanoparticle films compared to TiO2 cells and could offer a breakthrough in the efficiencies of DSSCs.
Neural correlates of intersensory processing in 5‐month‐old infants
Authors: Reynolds Greg D. , Bahrick Lorraine E. , Lickliter Robert , Guy Maggie W. 
Published: February 2013

AbstractTwo experiments assessing event‐related potentials in 5‐month‐old infants were conducted to examine neural correlates of attentional salience and efficiency of processing of a visual event (woman speaking) paired with redundant (synchronous) speech, nonredundant (asynchronous) speech, or no speech. In Experiment 1, the Nc component associated with attentional salience was greater in amplitude following synchronous audiovisual as compared with asynchronous audiovisual and unimodal visual presentations. A block design was utilized in Experiment 2 to examine efficiency of processing of a visual event. Only infants exposed to synchronous audiovisual speech demonstrated a significant reduction in amplitude of the late slow wave associated with successful stimulus processing and recognition memory from early to late blocks of trials. These findings indicate that events that provide intersensory redundancy are associated with enhanced neural responsiveness indicative of greater attentional salience and more efficient stimulus processing as compared with the same events when they provide no intersensory redundancy in 5‐month‐old infants. © 2013 Wiley Periodicals, Inc. © 2013Wiley Periodicals, Inc. Dev Psychobiol 56: 355–372, 2014.
Organic Chromophores Based on a Fused Bis‐Thiazole Core and Their Application in Dye‐Sensitized Solar Cells
Authors: Dessì Alessio , Barozzino Consiglio Gabriella , Calamante Massimo , Reginato Gianna , Mordini Alessandro , Peruzzini Maurizio , Taddei Maurizio , Sinicropi Adalgisa , Parisi Maria Laura , Fabrizi de Biani Fabrizia , Basosi Riccardo , Mori Riccardo , Spatola Michele , Bruzzi Mara , Zani Lorenzo 
Published: February 2013

AbstractFour new D‐π‐A organic dyes incorporating either a thiazolo[5,4‐d]thiazole bicyclic system (TTZ1–2) or a benzo[1,2‐d:4,5‐d′]bisthiazole tricyclic unit (BBZ1–2) have been synthesized and fully characterized. The key steps of the synthesis include an efficient MW‐assisted preparation of the thiazolo[5,4‐d]thiazole core and selective functionalization of two different dihalothienyl derivatives through Suzuki coupling. All the compounds showed photo‐ and electrochemical properties compatible with their employment in dye‐sensitized solar cells. In addition, their electronic structure and transitions were investigated by means of TD‐DFT calculations. Dye‐sensitized solar cells fabricated with dye TTZ1 yielded an average power conversion efficiency corresponding to 43 and 60 % of the performances recorded under the same conditions for cells containing reference dyes N3 and D5, respectively. Efficiency measurements and electrochemical impedance spectroscopy (EIS) experiments indicated that use of chenodeoxycholic acid (CDCA) as a co‐adsorbent was beneficial to disrupt dye‐dye interactions and slow down recombination processes within the cells, thus allowing power conversion efficiencies up to 3.53 % to be obtained.
Urine of patients with early prostate cancer contains lower levels of light chain fragments of inter‐alpha‐trypsin inhibitor and saposin B but increased expression of an inter‐alpha‐trypsin inhibitor heavy chain 4 fragment
Authors: Jayapalan Jaime J. , Ng Keng L. , Shuib Adawiyah S. , Razack Azad H. A. , Hashim Onn H. 
Published: February 2013

The present study was aimed at the identification of proteins that are differentially expressed in the urine of patients with prostate cancer (PCa), those with benign prostatic hyperplasia (BPH) and age‐matched healthy male control subjects. Using a combination of 2DE and MS/MS, significantly lower expression of urinary saposin B and two different fragments of inter‐alpha‐trypsin inhibitor light chain (ITIL) was demonstrated in the PCa patients compared to the controls. However, only one of the ITIL fragments was significantly different between the PCa and BPH patients. When image analysis was performed on urinary proteins that were transferred onto NC membranes and detected using a lectin that binds to O‐glycans, a truncated fragment of inter‐alpha‐trypsin inhibitor heavy chain 4 was the sole protein found to be significantly enhanced in the PCa patients compared to the controls. Together, these urinary peptide fragments might be useful complementary biomarkers to indicate PCa as well as to distinguish it from BPH, although further epidemiological evidence on the specificity and sensitivity of the protein candidates is required.
Determination of volatile phenols in Chinese liquors by high‐performance liquid chromatography associated with β‐cyclodextrin and a protective barrier layer
Authors: Peng Qianrong , Dong Rui , Xun Siying , Yang Min , Feng Yongyv , Sun Di , Geng Pinglan 
Published: February 2013

ABSTRACTVolatile phenols have been considered as a class of highly flavour‐active compounds in non‐alcoholic and alcoholic beverages. However, the information on volatile phenols in Chinese liquors remains limited. This article presents a high‐performance liquid chromatography with a fluorescence detector (HPLC‐FLD) method for the determination of 10 volatile phenols in Chinese liquors. The method was based on the fluorescent nature of volatile phenols, the separation of the isomers p‐cresol and m‐cresol with β‐cyclodextrin as the resolving agent, and the use of a protective barrier layer for the capture of volatile phenols during the concentration process of the extract solution. The effects of several experimental parameters on recoveries of target volatile phenols were investigated. The correlation coefficients (R2) for calibration curves of the 10 phenols studies were in the range 0.9991–0.9998 when the linearity range was from 0.05 to 4 µg/ml. The proposed RP‐HPLC method was successfully applied to the analysis of Chinese liquors and the recoveries of the phenols were in the range 91.5–100.4% with RSD 0.9–2.2%, and the limits of detection were 0.0072–0.0234 µg/ml. Volatile phenols of different types and in differing amounts were found in several Chinese liquors. The method could be of use for routine evaluation of the quantity of volatile phenols during the production and ageing process of Chinese liquors. Copyright © 2013 John Wiley & Sons, Ltd.
Damage and Failure of Silver Based Ceramic/Metal Joints for SOFC Stacks
Authors: Bause T. , Malzbender J. , Pausch M. , Beck T. , Singheiser L. 
Published: February 2013

AbstractThe increasing interest in lightweight solid oxide fuel cell (SOFC) systems for mobile applications has raised the awareness for questions concerning mechanical robustness of sealing materials in thermo‐cyclic operation. In the planar SOFC design considered in the current work, a metallic silver based braze sealant is used. Although, these rather ductile metallic seals are considered to have advantages compared to brittle glass ceramics under thermal cycling conditions, the behavior of such sealant materials after application relevant thermal cyclic operation has not been reported so far. Hence, the post‐operational characterization of a series of silver braze sealed stacks operated isothermally and under thermal cycling conditions is reported with particular emphasis on the braze morphology. The stacks were disassembled after operation, specimens were extracted in various characteristic positions, and metallographically prepared cross‐sections were analyzed by optical and electron microscopy. It was observed that micro‐pores were formed in the sealant that terminated stack operation, and that the extent of this porosity depended on the actual operation conditions leading eventually to leakage and in some cases even to melting effects. The discussion of the results focuses on the influence of different operation conditions on the damage progress and failure of silver based braze joints.
Preliminary analysis of age of illness onset effects on symptom profiles in major depressive disorder
Authors: Charlton Rebecca A. , Lamar Melissa , Ajilore Olusola , Kumar Anand 
Published: February 2013

ObjectiveMajor depressive disorder (MDD) is prevalent across the lifespan, but relatively little is known about how age of illness onset impacts the cognitive and affective presentation of MDD.MethodWe explore depressive symptoms and cognition in 70 adults (30–89 years old) with MDD. Participants were divided into three groups on the basis of age of MDD onset: early (<30 years), midlife (30–49.9 years), and late (>50 years). Symptoms were assessed using the Hamilton Depression Rating Scale; principal component analysis was used to create symptom component scores. Cognitive functions were measured.ResultsThe late‐onset group were significantly older than the early‐onset and midlife‐onset groups. Analysis controlled for age and hemoglobin A1c levels, as some participants had diabetes. The late‐onset group demonstrated greater weight loss and gastrointestinal symptoms compared with the early‐onset group. Suicidal thoughts and sleep disturbance were higher in both the early‐onset and late‐onset groups compared with the midlife‐onset group. Correlations between symptom components and cognitive domains varied by age‐of‐onset group.DiscussionThis preliminary analysis demonstrates cognitive and affective profiles that are both unique to age of onset and common across MDD. Symptom profiles may assist in identifying factors influencing depression and enhance the clinical evaluation and care of individuals struggling with the effects of depression across the lifespan. Copyright © 2013 John Wiley & Sons, Ltd.