bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrophilic, Upconverting, Multicolor, Lanthanide‐Doped NaGdF4 Nanocrystals as Potential Multifunctional Bioprobes
Authors: Li Feifei , Li Chunguang , Liu Xiaomin , Chen Ying , Bai Tianyu , Wang Long , Shi Zhan , Feng Shouhua 
Published: August 2012

AbstractMonodisperse water‐soluble hexagonal phase Ln3+‐doped NaGdF4 upconverting nanocrystals (UCNCs) have been successfully fabricated by means of a fast, facile, and environmentally friendly microwave‐assisted route with polyethylenimine as the surfactant. Fine‐tuning of the UC emission from visible to near‐IR and finally to white light has been achieved. Furthermore, studies of the magnetic resonance imaging as well as the magnetization (magnetization–magnetic field curves) and the targeted recognition properties of FA‐coupled amine‐functionalized NaGdF4@SiO2 UCNCs indicate that the obtained NaGdF4 UCNCs can be potential candidates for dual‐mode optical/magnetic bioapplications.
N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene
Authors: Alvarado Edwin , Badaj Anna C. , Larocque Timothy G. , Lavoie Gino G. 
Published: August 2012

AbstractGold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^ImineR), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^ImineR and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^ImineR and S^ImineR gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^IminetBu with [AuCl(SMe2)] led to the formation of [(C^IminetBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^IminetBu)2Au]+, with AuCl2− as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^IminetBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.
Proteasom‐Inhibitoren
Authors: Steverding Dietmar 
Published: August 2012

AbstractDas Proteasom ist ein multikatalytischer Proteasekomplex mit einem ungewöhnlichen Enzymmechanismus. Es spielt eine zentrale Rolle beim intrazellulären Proteinabbau und seine entscheidende Funktion in der Regulation des Zellzyklus macht es zu einem interessanten Ziel in der Krebstherapie. Zunächst als Reagenzien zur Aufklärung der katalytischen Funktionen des Proteasoms entwickelt, werden mittlerweile einige Proteasom‐Inhibitoren als Krebsmittel in klinischen Studien getestet. Besonders wirkungsvoll als Krebsmittel scheinen Proteasom‐Inhibitoren aus den Substanzklassen der Peptid‐Borsäuren, der Peptid‐Epoxyketone und der γ‐Lactam‐β‐lactone zu sein.
Eine Rinde erobert die Welt
Authors: Streller Sabine , Roth Klaus 
Published: August 2012

AbstractDie chininhaltige Rinde von Cinchona war das wohl wertvollste Heilmittel, das uns die Neue Welt geschenkt hat. Über Jahrhunderte war dies die einzige Medizin gegen Malaria und wird auch heute noch dafür eingesetzt. Die Isolierung, Strukturbestimmung und Totalsynthese des Chinins waren chemische Meisterstücke. Heute werden mit Cinchona‐Alkaloiden nicht nur verschiedene Krankheiten behandelt, sondern sie dienen als wirkungsvolle Katalysatoren und Hilfsstoffe zur Herstellung reiner Enantiomere in der Chemischen und Pharmazeutischen Industrie. Schließlich verleiht eine kleine Prise Chinin dem Tonic Water und einigen klassischen Cocktails das gewisse Etwas, das wir so genießen. Also, Prost auf alle Drinks, die dieses wunderbare Alkaloid enthalten, egal ob gerührt oder geschüttelt.
Feuerwerk
Authors: Keller Fritz 
Published: August 2012

AbstractDie Feuerwerkerei bzw. Pyrotechnik ist eine alte empirische Wissenschaft im Grenzbereich zwischen Chemie, Technik, Verfahrenstechnik und Kunst und hat ihren festen Platz bei vielen Events in Kultur und Brauchtum. Im Artikel wird dargestellt, welche Schritte ein Feuerwerk von der Chemie bis zur Show durchläuft. Einige chemische Grundlagen, Informationen zu pyrotechnischen Sätzen wie Schwarzpulver, Leuchtsätzen, oszillierenden Blink‐ und Pfeifsätzen werden erläutert und an Beispielen Aufbau und Herstellung von Feuerwerkskörpern in Text und Bild dargestellt. Aspekte der Sicherheit bei der Herstellung und bei Aufbau und Abbrennen eines Großfeuerwerks werden ebenso behandelt wie die neusten Entwicklungen in der Gesetzgebung, wie Pyrotechnikrichtlinie, CE‐Normung und REACH. Wenn auch das kommerzielle Umfeld der Feuerwerkerei schwieriger wird, bleibt die Faszination für die Phänomene des Feuerwerks ungebrochen und lässt für den Leser vielleicht die Motivation entstehen, sich mit dem spannenden Gebiet der Pyrotechnik und den angrenzenden Wissenschaften näher zu befassen.
Modelling of multicomponent gas separation with asymmetric hollow fibre membranes—methane enrichment from biogas
Authors: Kundu Prodip K. , Chakma Amit , Feng Xianshe 
Published: August 2012

AbstractA mathematical model for the dynamic performance of gas separation with high flux, asymmetric hollow fibre membranes was developed considering the permeate pressure build‐up inside the fibre bore and cross flow pattern with respect to the membrane skin. The solution technique provides reliable examination of pressure and concentration profiles along the permeator length (both residue/permeate streams) with minimal effort. The proposed simulation model and scheme were validated with experimental data of gas separation from literature. The model and solution technique were applied to investigate dynamic performance of several membrane module configurations for methane recovery from biogas (landfill gas or digester gas), considering biogas as a mixture of CO2, N2 and CH4. Recycle ratio plays a crucial role, and optimum recycle ratio vital for the retentate recycle to permeate and permeate recycle to feed operation was found. From the concept of two recycle operations, complexities involved in the design and operation of continuous membrane column were simplified. Membrane permselectivity required for a targeted separation to produce pipeline quality natural gas by methane‐selective or nitrogen‐selective membranes was calculated. © 2012 Canadian Society for Chemical Engineering
Characteristics of fluidisation behaviour in a pressurised bubbling fluidised bed
Authors: Li Haoyu , Yan Weiping , Wu Wei , Wang Chunbo 
Published: August 2012

AbstractThe experiments were carried out in a bench‐scale fluidised bed of 90 mm in diameter to determine the influence of pressure on fluidisation characteristics of Geldart A and B particles over the range of pressure 0.1–4.5 MPa. For Geldart B particles, the results indicate that minimum fluidisation velocity (umf) was found to decrease with pressure whilst bed voidage at umf was unaffected, and the bed expansion height increase with pressure at fixed value of gas velocity was observed for both Geldart B and A particles. For Geldart A particles, minimum bubbling velocity (umb) bed voidage at umb and dense phase voidage were found to increase obviously with pressure, but a slight influence of pressure on umf was observed. The prediction values of high‐pressure fluidisation characteristics from the references' correlations developed at pressure were in agreement with the experimental data. © 2012 Canadian Society for Chemical Engineering
Degradation of an Azo Dye with Homogeneous and Heterogeneous Catalysts by Sonophotolysis
Authors: Eren Zeynep 
Published: August 2012

AbstractThis study illustrates the degradation of an azo dye, Reactive Yellow 81 (RY81), by the combined irradiation of UV‐C and ultrasound in the presence of homogeneous (Fe2+) and heterogeneous (TiO2, ZnO) catalysts. The efficiency of homogeneous and heterogeneous oxidation systems was evaluated in regard of the decolorization and mineralization of RY81. Decolorization followed pseudo‐first‐order kinetics with homogeneous and heterogeneous catalysts. Complete color removal was accomplished by homogeneous sonocatalytic and sonophotocatalytic oxidation processes with apparent rate constants of 0.96 × 10−3 and 46.77 × 10−3 s−1, respectively, in the presence of Fe2+. However, partial color removal was obtained by heterogeneous sonocatalytic, photocatalytic, and sonophotocatalytic oxidation processes with apparent rate constants of 2.32 × 10−3, 3.60 × 10−3, and 3.67 × 10−3 s−1, respectively, in the presence of ZnO. TiO2 had the worst catalytic effect of all of the oxidation processes. The addition of hydrogen peroxide increased the rate constants of the heterogeneous oxidation processes and decreased the rate constants of the homogeneous oxidation processes. RY81 mineralization was 62.8% for the US/UV/Fe2+ homogeneous oxidation process, which was the best oxidation process, whereas it was 43.5% for the US/UV/ZnO/H2O2 heterogeneous oxidation process within 2 h reaction time.
A Study: Removal of Cu(II), Cd(II), and Pb(II) Ions from Real Industrial Water and Contaminated Water Using Activated Sludge Biomass
Authors: Kusvuran Erdal , Yildirim Deniz , Samil Ali , Gulnaz Osman 
Published: August 2012

AbstractThis study aims to remove of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass were optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS biomass (qmax) were calculated as 0.478, 0.358, and 0.280 mmol g−1 for Cu2+, Cd2+, and Pb2+, respectively, and the adsorption equilibrium time was found as 60 min for each metal. The adsorbed amount of metal rose with increasing of initial metal ion concentration. The equilibrium adsorption capacity of AS for initial 0.25 mmol L−1 metal concentration was determined as 0.200, 0.167, and 0.155 mmol g−1 for Cu2+, Cd2+, and Pb2+ ions, respectively. These relevant values were determined as 0.420, 0.305, and 0.282 mmol g−1 for Cu2+, Cd2+, and Pb2+ ions, respectively, when initial metal concentration was 0.50 mmol L−1. In the multi‐metal sorption system, the adsorption capacity of AS biomass was observed in the order of Cu2+ > Cd2+ > Pb2+. In the presence of 100 mmol L−1 H+ ion, the order of ion‐exchange affinity with H+ was found as Cu2+ > Cd2+ > Pb2+. The adsorption kinetics were also found to be well described by the pseudo‐second‐order and intraparticle diffusion models. Two different rate constants were obtained as ki1 and ki2 and ki1 (first stage) was found to be higher than ki2 (second stage).
Surficial and Vertical Distribution of Heavy Metals in Different Estuary Wetlands in the Pearl River, South China
Authors: Zhang Honggang , Cui Baoshan , Zhang Kejiang 
Published: August 2012

AbstractA total of 87 soil profiles sampled from five types of wetlands in the Pearl River estuary were analyzed to investigate the surficial and vertical distributions of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). The results show that wetlands directly connected with rivers (e.g., riparian wetlands, estuarine wetlands, and mangrove wetlands) has much higher metal concentrations than those indirectly connected with rivers (e.g., pond wetlands and reclaimed wetlands). The river water is the major pollution source for all investigated heavy metals. The vertical distribution of heavy metals can be classified into three patterns: (i) linear distribution pattern. The concentration of heavy metals gradually decreases with an increase in soil depth (for riparian and estuarine wetlands); (ii) irregular and stable pattern (for pond and reclaimed wetlands); and (iii) middle enrichment pattern (for mangrove wetlands). In addition to river‐borne inputs, a variety of vegetation composition, hydraulic conditions, and human activities also contribute to the variation in distribution of heavy metals in different wetlands. Soil properties (e.g., particle size, pH, salinity, and SOM) also affect the distribution of trace metals in each soil layer. The major pollution source of heavy metals is industrial wastewater. Other sources include agriculture and domestic premises, and atmospheric deposition. This study provides a sound basis for the risk assessment of heavy metals in the studied wetlands and for wetland conservation in general.
Nitrate–Nitrogen Transport in Horizontal Soil Columns of the Yellow River Delta Wetland, China
Authors: Bai Junhong , Ye Xiaofei , Zhi Yuan , Gao Haifeng , Huang Laibin , Xiao Rong , Shao Hongbo 
Published: August 2012

AbstractHorizontal movement of nitrate–nitrogen was simulated in horizontal soil columns from a typical tidal flooding wetland and a short‐term flooding wetland of the Yellow River Delta. The primary objectives of this study were to investigate the changes in transport fluxes of nitrate–nitrogen with increasing movement distances and to identify the relationship between transport fluxes of nitrate–nitrogen and water diffusion coefficients. The results showed that the transport fluxes of nitrate–nitrogen were significantly and negatively correlated with movement distances in both wetlands, and decreased exponentially with increasing distances. However, the transport fluxes of nitrate–nitrogen increased exponentially with increasing water diffusion coefficients in both wetlands. The higher transport fluxes of nitrate–nitrogen in surface soils were observed compared to deeper soils, while they were higher in surface soils at the distances near the tracer water head. The findings of this study can contribute to water quality protection by regulating buffer zone width based on the horizontal movement of nitrate–nitrogen.
Trafficking of Intermediate (KCa3.1) and Small (KCa2.x) Conductance, Ca2+‐Activated K+ Channels: a Novel Target for Medicinal Chemistry Efforts?
Authors: Balut Corina M. , Hamilton Kirk L. , Devor Daniel C. 
Published: August 2012

AbstractCa2+‐activated K+ (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro‐domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein–protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.
BRAF mutation detection in indeterminate thyroid cytology specimens
Authors: Ohori N. Paul , Singhal Rashi , Nikiforova Marina N. , Yip Linwah , Schoedel Karen E. , Coyne Christopher , McCoy Kelly L. , LeBeau Shane O. , Hodak Steven P. , Carty Sally E. , Nikiforov Yuri E. 
Published: August 2012

AbstractBACKGROUND:BRAF mutations are highly specific for papillary thyroid carcinoma (PTC) and many cytology specimens with BRAF mutations are expected to demonstrate cytologic features typical of PTC. However, indeterminate thyroid cytology cases are inevitable and understanding the significance of the BRAF mutation within the context of the Bethesda System for Reporting Thyroid Cytopathology would be valuable.METHODS:Thyroid cytology cases submitted for conventional cytomorphologic evaluation and BRAF mutational analyses were selected from the authors' cytopathology files from April 2007 to October 2011. From this group, the diagnostic usefulness of BRAF mutations in indeterminate and malignant cases was assessed and analyses of cytologic and histopathologic features associated with the mutations in this gene were performed.RESULTS:A total of 131 cases with a BRAF mutation were identified. Of these, 119 underwent surgical pathology resection follow‐up and demonstrated PTC. Approximately 75% of the cases were cytologically diagnosed as being positive for malignancy and these cases were associated with both the classic and tall cell variants of PTC at the time of resection, a greater likelihood of extrathyroidal extension, and the V600E type of BRAF mutation. In contrast, BRAF‐mutated cases with diagnoses of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) and follicular neoplasm/suspicious for follicular neoplasm were found to be more strongly associated with the follicular variant of PTC, a K601E BRAF mutation, and a lower likelihood of extrathyroidal extension. However, a subset of AUS/FLUS cases with the V600E BRAF mutation appeared to represent sampling variability of the classic or tall cell variants of PTC.CONCLUSIONS:Bethesda thyroid diagnoses in the setting of a BRAF mutation reflect differences in PTC subtypes, the nature of cytology specimens, and molecular characteristics. Cancer (Cancer Cytopathol) 2013;121:197–205. © 2012 American Cancer Society.
Unusual Regioselective Electrophilic Substitutions in Quinoline Foldamers: Conceptual DFT and Frontier Molecular Orbital Analysis Reveal the Crucial Role of Folding and Substituents
Authors: Shravani Madishetti , Balaiah Shanigaram , Srinivas Kolupula , Bhanuprakash K. , Huc Ivan 
Published: August 2012

AbstractWe carried out a detailed computational investigation of an earlier experimentally observed, unusual, regioselective, electrophilic halogenation in helically folded quinoline oligoamides. In the experimental studies, halogenation occurred selectively at a given monomer of a foldamer substituted with electron‐withdrawing groups at the N terminus, although apparently identical reactive sites were available to react with the incoming electrophile. On the other hand, the selectivity was lost with weakly electron‐donating groups. To gain an insight into the regioselective preference of bromination in quinoline foldamers, conceptual DFT was used to calculate the local nucleophilicity index of various foldamers of different sizes and with different substituents, and it was found that the predicted reaction centers were in line with the experimental results. Frontier molecular orbital analysis was used to understand this behavior. A detailed study of the hypothetical linear conformation of the tetramer for comparison with the folded conformation was carried out. In the case of a linear conformer, the HOMO is localized on specific monomers irrespective of substitution, but upon folding delocalization is observed, which is larger for the weakly electron‐donating groups when compared with the electron‐withdrawing groups. In the case of strongly donating groups there is no delocalization, even upon folding. The behavior remains the same when the size of the helix is increased (octamer). Thus, it is clearly seen in this work that the combined effects of conformations and substituents dictate the regioselectivity in the folded oligoamides; this knowledge will have a profound effect on the field of foldamer chemistry.
Two‐Photon Absorption and Time‐Resolved Stimulated Emission Depletion Spectroscopy of a New Fluorenyl Derivative
Authors: Belfield Kevin D. , Bondar Mykhailo V. , Morales Alma R. , Yue Xiling , Luchita Gheorghe , Przhonska Olga V. , Kachkovsky Olexy D. 
Published: August 2012

AbstractThe synthesis, comprehensive linear photophysical characterization, two‐photon absorption (2PA), steady‐state and time‐resolved stimulated emission depletion properties of a new fluorene derivative, (E)‐1‐(2‐(di‐p‐tolylamino)‐9,9‐diethyl‐9H‐fluoren‐7‐yl)‐3‐(thiophen‐2‐yl)prop‐2‐en‐1‐one (1), are reported. The primary linear spectral properties, including excitation anisotropy, fluorescence lifetimes, and photostability, were investigated in a number of aprotic solvents at room temperature. The degenerate 2PA spectra of 1 were obtained with open‐aperture Z‐scan and two‐photon induced fluorescence methods, using a 1 kHz femtosecond laser system, and maximum 2PA cross‐sections of ∼400–600 GM were obtained. The nature of the electronic absorption processes in 1 was investigated by DFT‐based quantum chemical methods implemented in the Gaussian 09 program. The one‐ and two‐photon stimulated emission spectra of 1 were measured over a broad spectral range using a femtosecond pump–probe‐based fluorescence quenching technique, while a new methodology for time‐resolved fluorescence emission spectroscopy is proposed. An effective application of 1 in fluorescence bioimaging was demonstrated by means of one‐ and two‐photon fluorescence microscopy images of HCT 116 cells containing dye encapsulated micelles.
Facile electrochemical synthesis of tellurium nanorods and their photoconductive properties
Authors: Li H. H. , Zhang P. , Liang C. L. , Yang J. , Zhou M. , Lu X. H. , Hope G. A. 
Published: August 2012

AbstractTellurium nanorods have been successfully fabricated by template and surfactant‐free electrochemical technique from an aqueous solution at room temperature. The as‐prepared tellurium nanorods were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry, UV‐vis spectroscopy and photoluminescence spectroscopy. Films based on tellurium nanorods were constructed to study the photoresponse and I‐V curves. These photoresponse measurements demonstrate that tellurium nanorods exhibited enhanced conductivity under illumination compared to in the dark measurement.
Supportless Silver Nanowires as Oxygen Reduction Reaction Catalysts for Hydroxide‐Exchange Membrane Fuel Cells
Authors: Alia Shaun M. , Duong Kathlynne , Liu Toby , Jensen Kurt , Yan Yushan 
Published: August 2012

AbstractSilver nanowires (AgNWs) and nanoparticles (AgNPs) have been synthesized to facilitate hydroxide‐exchange membrane fuel cell development and commercialization. AgNWs and AgNPs with variable diameters (25–60 nm AgNWs, 2.4–30 nm AgNPs) have been studied with rotating‐disk electrode experiments to examine the impact of size and morphology on the oxygen reduction reaction (ORR). Although a detrimental particle size effect is observed, AgNWs exceed the specific activity of bulk polycrystalline Ag. AgNWs with a diameter of 25 nm further exceed the ORR specific and mass activity of 2.4 nm AgNPs 5.3 times and by 16 %, respectively. Rotating ring‐disk electrode testing demonstrates minimal peroxide formation on AgNWs; peroxide production increases with the use of AgNPs by as much as an order of magnitude and further increases with particle size reduction. Silver catalysts demonstrate alcohol tolerance for ORR, illustrating the benefit of silver and AgNWs as catalysts in hydroxide and alcohol hydroxide‐based fuel cells.