bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diketopyrrolopyrrole–Porphyrin Conjugates as Broadly Absorbing Sensitizers for Dye‐Sensitized Solar Cells
Authors: Warnan Julien , Favereau Ludovic , Meslin Frédéric , Severac Marjorie , Blart Errol , Pellegrin Yann , Jacquemin Denis , Odobel Fabrice 
Published: July 2012

AbstractA series of four new push–pull zinc porphyrin‐based dyes was synthesised for hybrid photovoltaic solar cells with a view to enhancing the light‐harvesting efficiency at approximately 550 nm with a diketopyrrolopyrrole (DPP) unit. The strength of the donor side of the push–pull porphyrin was tuned by affixing the electron‐rich 4,4′‐dimethoxydiphenylamine group at the meso position of the macrocycle, and the influence of the distance between the semiconductor surface and the porphyrin chromophore was assessed by introducing different π‐conjugated spacers. Charge‐transfer transitions over great distances were characterised by electronic absorption spectroscopy and DFT calculations. The absorption and photoactivity spectra of the new bichromophoric dyes spans the whole visible spectrum to the red, implying a better light‐harvesting efficiency than regular porphyrin as the absorption spectra of DPP and porphyrin complement one another. Photovoltaic conversion efficiencies accordingly increase from 2.40 to 5.19 %. Interestingly, the best overall efficiency was reached with dye 3, which lacks the powerful donating group in the meso position of the porphyrin core. Optical and electrochemical measurements coupled to time dependent (TD)‐DFT calculations give insight into the deleterious effect of the 4,4′‐dimethoxydiphenylamine unit on the photovoltaic performances, paving the way towards the design of efficient push–pull porphyrin‐based sensitizers.
Cytometric and biochemical characterization of human breast cancer cells reveals heterogeneous myoepithelial phenotypes
Authors: Leccia Felicia , Nardone Agostina , Corvigno Sara , Vecchio Luigi Del , De Placido Sabino , Salvatore Francesco , Veneziani Bianca Maria 
Published: July 2012

AbstractTo determine whether cell cultures maintain the cellular heterogeneity of primary tissues and may therefore be used for in vitro modeling of breast cancer subtypes, we evaluated the expression of a cell surface marker panel in breast cancer cell cultures derived from various subtypes of human breast carcinoma. We used a four‐color flow cytometry strategy to immunophenotype seven human breast cancer cell cultures and four reference breast cancer cell lines. We analyzed 28 surface markers selected based on their potential to distinguish epithelial or mesenchymal lineage, to identify stem cell populations, and to mediate cell adhesion and migration. We determined their ability to form mammospheres and analyzed luminal cytokeratins CK18, CK19, and myoepithelial/basal CK5, SMA (alpha‐smooth muscle actin), and vimentin expression by western blot. All cell surface markers showed a unimodal profile. Ten/28 markers were homogenously expressed. Four (CD66b, CD66c, CD165, CD324) displayed negative/low expression. Six (CD29, CD55, CD59, CD81, CD151, CD166) displayed homogenous high expression. Eighteen (CD9, CD10, CD24, CD26, CD44, CD47, CD49b, CD49f, CD54, CD61, CD90, CD105, CD133, CD164, CD184, CD200, CD227, CD326) were heterogeneously expressed. Spearman's rank test demonstrated a significant correlation (p< 0.001) between mesenchymal phenotype and breast cancer cell cultures. Breast cancer cell cultures, all CD44+, displayed concomitant high expression of only three antigens (CD10, CD54, CD90), and low expression of CD326; cell cultures formed mammospheres and expressed CK5, SMA and vimentin, and were weakly CK19‐positive. We demonstrate that breast cancer cell cultures preserve inter‐tumor heterogeneity and express stem/progenitor markers that can be identified, quantified and categorized by flow cytometry. Therefore, cell cultures can be used for in vitro modeling of breast cancer subtypes; immunophenotyping may mirror breast cancer heterogeneity and reveal molecular characteristics of individual tumors useful for testing target therapy. © 2012 International Society for Advancement of Cytometry
Synthesis of WN(NMe2)3 as a Precursor for the Deposition of WNx Nanospheres
Authors: McClain K. Randall , O'Donohue Christopher , Shi Zhiwei , Walker Amy V. , Abboud Khalil A. , Anderson Tim , McElwee‐White Lisa 
Published: July 2012

AbstractThe WNx precursor WN(NMe2)3 was prepared from WN(OtBu)3 and Zr(NMe2)4 by using an amide/alkoxide exchange reaction. Structural analysis of WN(NMe2)3 revealed an overall pseudo‐tetrahedral geometry with a distortion towards trigonal pyramidal. Aerosol‐assisted chemical vapor deposition (AACVD) from WN(NMe2)3 resulted in deposition of WNx nanospheres onto Si(100) and Si(111) substrates at low temperatures (75–125 °C). The nanospheres were imaged by SEM and characterized by using energy dispersive spectroscopy (EDS) and X‐ray photoelectron spectroscopy (XPS). These preliminary results demonstrate the viability of WN(NMe2)3 as a single‐source precursor for the deposition of WNx at low temperature.
Synthesis and Characterization of Pyrylogens Possessing Low Excitation Energies – Substituent Modification in Order to Improve Solar Energy Collection
Authors: El‐Idreesy Tamer T. 
Published: July 2012

AbstractThe synthesis and characterization of the first di‐β‐naphthyl‐substituted pyrylogens, N‐methyl‐2,6‐di‐β‐naphthyl‐4,4′‐pyrylogen bis(tetrafluoroborate) and N‐methyl‐2,6‐di‐β‐naphthyl‐4,2′‐pyrylogen bis(tetrafluoroborate) are reported. The photophysical and electrochemical behaviors of these new pyrylogens are examined and compared to the previously reported diphenyl‐substituted analogs, N‐methyl‐2,6‐diphenyl‐4,4′‐pyrylogen bis(tetrafluoroborate) and N‐methyl‐2,6‐diphenyl‐4,2′‐pyrylogen bis(tetrafluoroborate) as well as to 2,4,6‐triphenylpyrylium tetrafluoroborate, the typical electron‐transfer photocatalyst. The newly synthesized pyrylogens exhibit substantially lower excitation energies. The results are supported by theoretical calculations using the B3LYP/6‐31G(d) and time‐dependent DFT (TD‐DFT) CAM‐B3LYP/6‐31G(d) computational models. In addition, insight into the reduction reactions of the new pyrylogens to their radical cation and neutral redox partners is also provided.
AgI‐Catalyzed Cascade Strategy: Regioselective Access to Diversely Substituted Fused Benzimidazo[2,1‐a]isoquinolines, Naphthyridines, Thienopyridines, and Quinoxalines in Water
Authors: Rustagi Vineeta , Tiwari Rakesh , Verma Akhilesh Kumar 
Published: July 2012

AbstractAn environmentally benign and operationally simple one‐pot approach to the regioselective tandem synthesis of diversely substituted fused benzimidazo[2,1‐a]isoquinolines, naphthyridines, thienopyridines, and quinoxalines from o‐alkynylaldehydes and arylamines with tethered nucleophiles using AgI as catalyst in water is described. The reaction showed selective N–C bond formation on the more electrophilic alkynyl carbon, resulting in the regioselective 6‐endo‐dig cyclized products in good to excellent yields. The proposed mechanistic pathway for the synthesis of fused heterocycles proceeding through formation of ring A prior to ring B, which formed through a second intramolecular attack of the nitrogen onto the alkynyl carbon, was supported by mechanistic experiments and X‐ray crystallographic studies of isolated intermediate U and cyclized product 5a. Comparative experiments showed the viability of intramolecular nucleophilic attack over intermolecular attack of an external nucleophile. This catalytic, green protocol has been efficiently applied for the bis‐tandem cyclization in water.
Conformational Dynamics of a Central Trisaccharide Fragment of the LeaLex Tumor Associated Antigen Studied by NMR Spectroscopy and Molecular Dynamics Simulations
Authors: Zaccheus Mona , Pendrill Robert , Jackson Trudy A. , Wang An , Auzanneau France‐Isabelle , Widmalm Göran 
Published: July 2012

AbstractCertain carbohydrate structures are recognized as cancer antigens, and identification of these and relevant epitopes are essential in fighting the disease. The trisaccharide β‐D‐GlcpNAc‐(1→3)‐β‐D‐Galp‐(1→4)‐β‐D‐GlcpNAc‐OMe represents a model for the central region of the LeaLex hexasaccharide and it has herein been investigated by 1D 1H,1H‐NOESY experiments to obtain effective interresidue proton–proton distances as well as by 2D J‐HMBC experiments to determine transglycosidic 3JCH coupling constants. Molecular dynamics (MD) simulations using explicit water as solvent and three different carbohydrate force fields, namely, GLYCAM06, PARM22/SU01, and CHARMM2011, were employed for the interpretation of experimental data. Overall, the force field based MD simulations are able to reproduce the experimental data and the ψ torsion angle at the β‐(1→3)‐linkage is concluded to be flexible. In addition, different minor states were present for the three force fields with either anti‐ψ or non‐exo‐anomeric conformations. Transitions between the exo‐anomeric and the non‐exo‐anomeric conformations for the φ torsion angle at the β‐(1→4)‐linkage in one of the MD simulations were analyzed in detail. It was found that hydrogen‐bonding water molecules, interresidue hydrogen bonds and the transitions between antiperiplanar and synperiplanar conformations for the τH torsion angle of an N‐acetyl group were all essential in the description of the glycosidic transition process. In particular, the transition of τH may be a general way of regulating other transitions into less populated but biologically important conformational regions.
Interruption of nuclear localization of ATBF1 during the histopathologic progression of head and neck squamous cell carcinoma
Authors: Sun Xiaodong , Li Jie , Sica Gabriel , Fan Song‐Qing , Wang Yuxiang , Chen Zhengjia , Muller Susan , Chen Zhuo (Georgia) , Fu Xiaoying , Dong Xue‐Yuan , Guo Peng , Shin Dong M. , Dong Jin‐Tang 
Published: July 2012

AbstractBackgroundThe AT‐motif binding factor 1 (ATBF1) gene is frequently altered at the genetic level in several types of cancer, but its protein expression and subcellular localization have not been well studied in human cancers, including head and neck squamous cell carcinomas (HNSCCs).MethodsATBF1 expression and localization were examined in 5 cell lines and 197 clinical specimens of HNSCC, and correlated with pathologic and clinical characteristics.ResultsATBF1 was predominantly localized in the nucleus of hyperplastic squamous epithelium. Whereas nuclear ATBF1 dramatically decreased in invasive tumors (p = .0012), cytoplasmic ATBF1 levels progressively increased from dysplasia to invasive tumors (p < .0001), and the increase correlated with poor survival. Reduced nuclear ATBF1 level was also detected in HNSCC cell lines.ConclusionsNuclear localization of ATBF1 is frequently interrupted in HNSCC, and the interruption is significantly associated with the progression of HNSCC. The cytoplasmic ATBF1 level could be useful for predicting patient survival. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Minimally invasive video‐assisted thyroidectomy: Learning curve in terms of mean operative time and conversion and complication rates
Authors: Pons Yoann , Vérillaud Benjamin , Blancal Jean–Philippe , Sauvaget Elisabeth , Cloutier Tam , Le Clerc Nicolas , Herman Philippe , Kania Romain 
Published: July 2012

AbstractBackgroundThe purpose of this study was to evaluate the learning curve for minimally invasive video‐assisted thyroidectomy (MIVAT).MethodsFifty consecutive patients were prospectively included in groups corresponding to their surgical order (10 patients in each group).ResultsThe mean operation times between 2 neighboring groups were 33.9 minutes longer in group 1 than in group 2 (p = .01) and 25.8 minutes longer in group 3 than in group 4 (p = .002). The conversion rate for technical difficulties in group 1 was 6% (3 of 50). The definitive complication rate was 2% (1 of 50).ConclusionsIn terms of operative time, 10 patients represented the early stage of the learning curve, and 30 patients represented the number of procedures required to reach an advanced level of skill. Considering the low conversion and complication rates, improved aesthetic results and postoperative course, MIVAT should become a tool in the repertoire of high‐volume thyroid surgeons. © 2012 Wiley Periodicals, Inc. Head Neck, 2013
Transformation/dissolution examination of antimony and antimony compounds with speciation of the transformation/dissolution solutions
Authors: Skeaff James M , Beaudoin Robert , Wang Ruiping , Joyce Barry 
Published: July 2012

Abstract
Speciation is held to be a key factor in controlling the ecotoxicity of metals in solution. Using the United Nations transformation/dissolution protocol (T/DP) for metals and sparingly soluble metal compounds, we have examined the transformation/dissolution (T/D) characteristics in terms of the concentrations of total dissolved Sb at pH 6 and 8.5 in 1, 10, and 100 mg/L loadings over 7 d as well as the concentrations of Sb(III) and Sb(V) at the 1 mg/L loadings over 28 d, of sodium hexahydroxoantimonate (NaSb(OH)6), antimony metal (Sb), antimony trioxide (Sb2O3), antimony sulfide (Sb2S3), sodium antimonate (NaSbO3), antimony tris(ethylene glycolate) (Sb2(C2H4O2)3), antimony trichloride (SbCl3), antimony triacetate (Sb(CH3COO)3), and antimony pentoxide (Sb2O5). We also measured the concentrations of the dissolved Sb(III) and Sb(V) species at the 1 mg/L loadings. Because of complexing, the trivalent organic Sb compounds exhibited little or no oxidation of Sb(III) to Sb(V). However, oxidation of Sb(III) to Sb(V) was evident for the trivalent inorganic Sb compounds. Conversely, with pentavalent Sb compounds, there was no reduction of Sb(V) to Sb(III). Based on the percentage of Sb in the compound dissolved or metal reacted at 28 d and 1 mg/L loadings, the solubility rankings at pH 6 are NaSb(OH)6 &gt; Sb(CH3COO)3 &gt; Sb metal &gt; Sb2(C2H4O2)3 &gt; Sb2S3 &gt; Sb2O3 &gt; NaSbO3 ≈ SbCl3 &gt; Sb2O5. For pH 8.5 the order is NaSb(OH)6 &gt; Sb(CH3COO)3 &gt; Sb metal &gt; Sb2(C2H4O2)3 &gt; SbCl3 &gt; Sb2O3 &gt; Sb2S3 &gt; NaSbO3 &gt; Sb2O5. We provide worked examples of how the T/D data have been used to derive hazard classification proposals for Sb metal and these selected compounds for submission to the European Chemicals Agency under the Registration, Evaluation, Authorization and Restriction of CHemicals (REACH) legislation. Integr Environ Assess Manag 2013; 9: 98–113. © 2012 SETAC
Light‐Activated Pharmaceuticals: Mechanisms and Detection
Authors: Kessel David , Reiners John 
Published: July 2012

AbstractPhotodynamic therapy relies on the interaction between light, oxygen and a photosensitizing agent. Its medical significance relates to the ability of certain agents, usually based on porphyrin or phthalocyanine structures, to localize somewhat selectively in neoplastic cells and their vasculature. Subsequent irradiation, preferably at a sufficiently high wavelength to have a significant pathway through tissues, results in a photophysical reaction whereby the excited state of the photosensitizing agent transfers energy to molecular oxygen and results in the formation of reactive oxygen species. Analogous reactive nitrogen species are also formed. These contain both nitrogen and oxygen atoms. The net result is both direct tumor cell death and a shutdown of the tumor vasculature. Other processes may also occur that promote the anti‐tumor response but these are outside the scope of this review.
The Role of Symmetry in Asymmetric Catalysis
Authors: Moberg Christina 
Published: July 2012

AbstractChiral ligands and metal complexes with rotational (Cn, Dn) symmetry often have beneficial properties in asymmetric catalysis. The enhanced enantioselectivity frequently observed is a result of a reduction of competing reaction routes. This may be due to rotational symmetry in the catalyst, leading to a limited number of different catalyst‐substrate interactions, or to formation of a limited number of catalytic species as a result of rotational symmetry in the ligand. The effect of symmetry is usually difficult to evaluate, since a change in symmetry properties necessarily is accompanied by structural modifications. In each situation the number of intermediate complexes, their electronic and steric properties, and their energy need to be analyzed. Although other factors may be more important than symmetry for achieving high enantioselectivity, a vast number of C2‐ and to some extent C3‐symmetric ligands have been found to have excellent properties in asymmetric catalysis, providing products with high enantiomeric purity. Besides the benefit of symmetry in the ligand and catalyst, the symmetry of the substrate may be important since a gain in enantioselectivity can result from simultaneous asymmetric transformations of homotopic functional groups.
Ecotoxicity and screening level ecotoxicological risk assessment of five antimicrobial agents: triclosan, triclocarban, resorcinol, phenoxyethanol and p‐thymol
Authors: Tamura Ikumi , Kagota Kei‐ichiro , Yasuda Yusuke , Yoneda Saori , Morita Junpei , Nakada Norihide , Kameda Yutaka , Kimura Kumiko , Tatarazako Norihisa , Yamamoto Hiroshi 
Published: July 2012

ABSTRACTAcute and chronic (or sub‐chronic) toxicity of five selected antimicrobial agents, including triclosan (TCS), triclocarban (TCC), resorcinol, phenoxyethanol and p‐thymol, was investigated using the conventional three‐aquatic‐organism battery. These compounds are widely used in cosmetics and other personal care products and their ecological risk has recently become a significant concern. As results of toxicity tests, TCS was found to be most strongly toxic for green algae [e.g. 72 h no observed effect concentration (NOEC) of 0.50 µg l−1] among the selected compounds, followed by TCC, while TCC was more toxic or similar to TCS for Daphnia and fish (e.g. Daphnia 8 day NOEC of 1.9 µg l−1). Having compared the predicted no effect concentration (PNEC) determined from the toxicity data with measured environmental concentrations (MEC), the preliminary ecological risk assessment of these five antimicrobials was conducted. The MEC/PNEC ratios of TCS and TCC were over 1 for some monitoring data, especially in urban streams with watershed areas without sewage service coverage, and their potential risk for green algae and Daphnia might be at a level of concern, although the contribution of TCS/TCC on the total toxicity of the those sites needs to be further investigated. For the three other antimicrobials, the maximum MEC/PNEC ratio for resorcinol was 0.1–1, but those for phenoxyethanol and p‐thymol were <0.1 and their risk to aquatic organisms is limited, although the additive effects with TCS, TCC and other antimicrobial agents, such as parabens, need to be further examined in future studies. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of Structure and Conformation on Fluorescence Properties in Novel Coumarin‐based Mannich Base Dyes
Authors: Ni Xiaobo , Guo Yuan , Bu Huaiyu , An Jing , En Da 
Published: July 2012

AbstractTwelve novel coumarin‐based Mannich base dyes have been synthesized via introducing functional aminomethyl group at the 8 position of coumarin ring by Mannich reaction and their chemical structures were confirmed by IR, 1H NMR, MS and elemental analysis. Moreover, the fluorescence intensities and relative quantum yields of all the dyes were measured and studied. The results illustrated that the heavy atom effect was obvious in our designed system and there was a relationship between the structures, the conformations and the fluorescence spectra of the coumarins. Meanwhile, the present β‐CD titration experiment illustrated that the aniline nitrogen atom was closely related to the photoinduced electron transfer (PET) course and the PET course was carried out via a conformational control mechanism.
Zwitterionic Salts from the Reaction of Symmetrical and Unsymmetrical (thio)Barbituric Acids with 2‐Pyridinecarbaldehyde under Solvent‐free Condition
Authors: Pesyan Nader Noroozi , Hosseini Yaser , Shokr Alireza , Şahin Ertan 
Published: July 2012

AbstractA simple and efficient synthesis for the preparation of unusual charge‐separated pyridinium (thio)barbiturate zwitterion derivatives was achieved via a one‐pot reaction of (thio)barbituric acid derivatives and 2‐pyridinecarbaldehyde under solvent‐free condition and also in methanol under refluxing. The structure of the compounds was confirmed by 1H NMR, 13C NMR, FT‐IR, mass and X‐ray analysis. The mechanism of the formation is discussed. Instead, no related pyridinium zwitterion was afforded from the reaction between dimedone and 2‐pyridinecarbaldehyde under the same conditions and its xanthene derivative was obtained.
Mechanochemical Synthesis of Tin Nanowires for Anodes in Li+ Ion Secondary Batteries
Authors: Tapia‐Ruiz Nuria , Nithya C. , Jayakrishnan Sobha , Gopukumar S. , Gregory Duncan H. 
Published: July 2012

AbstractTin micro‐ and nanowires have been synthesised for the first time via high‐energy ball milling techniques. Typically nanowires with diameters measuring ca. 500 nm and lengths of up to 100 μm were fabricated by milling powders of tin metal and lithium nitride, Li3N in 3:1 or 5:1 molar ratios. The as‐prepared products were characterised and analysed by powder X‐ray diffraction (PXRD), Raman spectroscopy, scanning electron microscopy (SEM) and Energy Dispersive X‐ray Analysis (EDX). Combined experimental evidence would suggest that the elemental nanowires grow in the presence of the tin‐rich alloy Li2Sn5. The composites were tested as anodes for secondary lithium‐ion batteries and even for non‐optimised materials demonstrate appreciable and promising discharge capacities.
Synthesis and Characterization of Hybrid Pt/NiO/MWCNTs Electrocatalysts
Authors: Cheng I‐Ling , Chiou Yuh Jing , Lin Hong Ming 
Published: July 2012

AbstractTo search for more efficient and inexpensive electrocatalysts is one of the main research directions for the electrocatalytic application of direct liquid fuel cells. Nanohybrid Pt/NiO/MWCNTs are synthesized by impregnation and polyol methods. Two different series denoted as Pt/[NiO/MWCNTs (1:4)] and NiO/[Pt/MWCNTs (1:4)] are prepared. The sizes of the nanoparticles are 3‐7 nm and 10 nm for Pt and NiO, respectively. By observing the morphology images, NiO will aggregate more on Pt modified MWCNTs than those without Pt adding. The catalytic properties of these hybrid catalysts are characterized by methanol electro‐oxidation. The addition of 20 wt% NiO, before or after Pt synthesis, can better enhance the catalysis ability of Pt and help Pt catalyst convert CO in lower temperature. This study indicates the 10 wt% Pt/[NiO/MWCNTs (1:4)] catalyst has the best performance in electrocatalytic activity for methanol. The NiO is a cheaper material than other commonly used oxides; the novel hybrid catalysts are a promised candidate for the electrocatalytic application in DMFCs.
Unsymmetrical Squaraines Incorporating Cabazole as a Donor for Dye‐Sensitized Solar Cells
Authors: Li Jheng‐Ying , Lin Tsu‐Han , Chen Szu‐Chien , Wu Chun‐Guey 
Published: July 2012

AbstractThree unsymmetrical squaraines, where the electron‐rich thiophene or bithiophene conjugated fragment was used to link unconventionally the squaraine core and carbazole (or methyl) group, were prepared. JYL‐SQ1 with thiophene as a donor and indoline‐carboxylic acid as an acceptor has λmax of 568 nm which is much longer than the general metal‐free organic dyes. Adding a carbazole unit in JYL‐SQ1 (forms JYL‐SQ2) can red‐shift the λmax to 603 nm. However, cabazole is not a strong donor (and indoline‐carboxylic acid is a weak acceptor) the LUMO of all three dyes are delocalized majorly on squaraine unit: the excited electrons of dye molecules injecting into TiO2 are not so efficiency, resulting in low short‐circuit current and conversion efficiency. The corresponding DSSC devices have the conversion efficiency of 0.71%, 2.59% and 2.22% for JYL‐SQ1, JYL‐SQ2 and THL‐SQ3, respectively.