bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum dot binding to DNA: Single‐molecule imaging with atomic force microscopy
Authors: Li Kungang , Zhang Wen , Chen Yongsheng 
Published: August 2012

AbstractThe interaction between nanoparticles (NPs) and DNA is of significance for both application and implication research of NPs. In this study, a single‐molecule imaging technique based on atomic force microscopy (AFM) was employed to probe the NP‐DNA interactions with quantum dots (QDs) as model NPs. Reproducible high‐quality images of single DNA molecules in air and in liquids were acquired on mica by optimizing sample preparation conditions. Furthermore, the binding of QDs to DNA was explored using AFM. The DNA concentration was found to be a key factor influencing AFM imaging quality. In air and liquids, the optimal DNA concentration for imaging DNA molecules was approximately 2.5 and 0.25 μg/mL, and that for imaging DNA binding with QDs was 0.5 and 0.25 μg/mL, respectively. In the presence of QDs, the DNA conformation was altered with the formation of DNA condensates. Finally, the fine conformation of QD‐DNA binding sites was examined to analyze the binding mechanisms. This work will benefit investigations of NP‐DNA interactions and the understanding of the structure of NP‐DNA bioconjugates.See accompanying article by Wang DOI: 10.1002/biot.201200309
Molecular crosstalk between cancer cells and tumor microenvironment components suggests potential targets for new therapeutic approaches in mobile tongue cancer
Authors: Dayan Dan , Salo Tuula , Salo Sirpa , Nyberg Pia , Nurmenniemi Sini , Costea Daniela Elena , Vered Marilena 
Published: August 2012

AbstractWe characterized tumor microenvironment (TME) components of mobile tongue (MT) cancer patients in terms of overall inflammatory infiltrate, focusing on the protumorigenic/anti‐inflammatory phenotypes and on cancer‐associated fibroblasts (CAFs) in order to determine their interrelations and associations with clinical outcomes. In addition, by culturing tongue carcinoma cells (HSC‐3) on a three‐dimensional myoma organotypic model that mimics TME, we attempted to investigate the possible existence of a molecular crosstalk between cancer cells and TME components. Analysis of 64 cases of MT cancer patients revealed that the overall density of the inflammatory infiltrate was inversely correlated to the density of CAFs (P = 0.01), but that the cumulative density of the protumorigenic/anti‐inflammatory phenotypes, including regulatory T cells (Tregs, Foxp3+), tumor‐associated macrophages (TAM2, CD163+), and potentially Tregs‐inducing immune cells (CD80+), was directly correlated with the density of CAFs (P = 0.01). The hazard ratio (HR) for recurrence in a TME rich in CD163+ Foxp3+ CD80+ was 2.9 (95% CI 1.03–8.6, P = 0.043 compared with low in CD163+ Foxp3+ CD80+). The HR for recurrence in a TME rich in CAFs was 4.1 (95% confidence interval [CI] 1.3–12.8, P = 0.012 compared with low in CAFs). In vitro studies showed cancer‐derived exosomes, epithelial–mesenchymal transition process, fibroblast‐to‐CAF‐like cell transdifferentiation, and reciprocal interrelations between different cytokines suggesting the presence of molecular crosstalk between cancer cells and TME components. Collectively, these results highlighted the emerging need of new therapies targeting this crosstalk between the cancer cells and TME components in MT cancer.
Chemical Shifts in Nucleic Acids Studied by Density Functional Theory Calculations and Comparison with Experiment
Authors: Fonville Judith M. , Swart Marcel , Vokáčová Zuzana , Sychrovský Vladimír , Šponer Judit E. , Šponer Jiří , Hilbers Cornelis W. , Bickelhaupt F. Matthias , Wijmenga Sybren S. 
Published: August 2012

AbstractNMR chemical shifts are highly sensitive probes of local molecular conformation and environment and form an important source of structural information. In this study, the relationship between the NMR chemical shifts of nucleic acids and the glycosidic torsion angle,χ, has been investigated for the two commonly occurring sugar conformations. We have calculated by means of DFT the chemical shifts of all atoms in the eight DNA and RNA mono‐nucleosides as a function of these two variables. From the DFT calculations, structures and potential energy surfaces were determined by using constrained geometry optimizations at the BP86/TZ2P level of theory. The NMR parameters were subsequently calculated by single‐point calculations at the SAOP/TZ2P level of theory. Comparison of the1H and13C NMR shifts calculated for the mono‐nucleosides with the shifts determined by NMR spectroscopy for nucleic acids demonstrates that the theoretical shifts are valuable for the characterization of nucleic acid conformation. For example, a clear distinction can be made betweenχangles in theantiandsyndomains. Furthermore, a quantitative determination of theχangle in thesyndomain is possible, in particular when13C and1H chemical shift data are combined. The approximate linear dependence of the C1′ shift on theχangle in theantidomain provides a good estimate of the angle in this region. It is also possible to derive the sugar conformation from the chemical shift information. The DFT calculations reported herein were performed on mono‐nucleosides, but examples are also provided to estimate intramolecularly induced shifts as a result of hydrogen bonding, polarization effects, or ring‐current effects.
Visible‐Light‐Induced Photocatalytic Hydrogen Production over Binuclear RuII–Bipyridyl Dye‐Sensitized TiO2 without Noble Metal Loading
Authors: Zhang Xiaohu , Veikko Uahengo , Mao Jin , Cai Ping , Peng Tianyou 
Published: August 2012

AbstractHighly efficient, visible light induced photocatalytic H2 production was achieved over a TiO2 system sensitized by binuclear RuII bipyridyl (bpy) complex [Ru2(bpy)4(BL)](ClO4)2 (BL=bridging ligand) without Pt loading, which is almost unaffected by pH in aqueous solution in the wide range from pH 5.00 to 10.50, although the dye molecules can only be loosely attached to TiO2 due to the absence of terminal carboxyl groups. The photocatalyst shows remarkable long‐term stability and reproducibility of H2 evolution even after exchanging the aqueous triethanolamine solution. The amount of H2 evolved over 100 mg of photocatalyst in 27 h of irradiation corresponds to a turnover number of about 75 340, and the apparent quantum yields are estimated to be 16.8 and 7.3 % under 420 and 475 nm monochromatic light irradiation, respectively. A comparative study shows that the loosely attached dye [Ru2(bpy)4(BL)](ClO4)2 has higher photosensitization efficiency than tightly linked dyes with terminal carboxyl groups, such as [Ru2(dcbpy)4(BL)](ClO4)2 and N719. It can be rationalized by their different coordination, physicochemical, electron‐injection, and back‐transfer properties.
Acceptor‐Substituted Ferrocenium Salts as Strong, Single‐Electron Oxidants: Synthesis, Electrochemistry, Theoretical Investigations, and Initial Synthetic Application
Authors: Khobragade Dushant A. , Mahamulkar Shraddha G. , Pospíšil Lubomír , Císařová Ivana , Rulíšek Lubomír , Jahn Ullrich 
Published: August 2012

AbstractA series of mono‐ and 1,1′‐diheteroatom‐substituted ferrocene derivatives as well as acylated ferrocenes was prepared efficiently by a unified strategy that consists of selective mono‐ and 1,1′‐dilithiation reactions and subsequent coupling with carbon, phosphorus, sulfur and halogen electrophiles. Chemical oxidation of the ferrocene derivatives by benzoquinone, 2,3‐dichloro‐5,6‐dicyanobenzoquinone, AgPF6, or 2,2,6,6‐tetramethyl‐1‐oxopiperidinium hexafluorophosphate provided the corresponding ferrocenium salts. The redox potentials of the synthesized ferrocenes were determined by cyclic voltammetry, and it was observed that all new ferrocenium salts have stronger oxidizing properties than standard ferrocenium hexafluorophosphate. An initial application of selected derivatives in an oxidative bicyclization revealed that they mediate the transformation under considerably milder conditions than ferrocenium hexafluorophosphate. Quantum chemical calculations of the reduction potentials of the substituted ferrocenium ions were carried out by using a standard thermodynamic cycle that involved the gas‐phase energetics and solvation energies of the contributing species. A remarkable agreement between theory and experiment was found: the mean average deviation amounted to only 0.030 V and the maximum deviation to 0.1 V. This enabled the analysis of various physical contributions to the computed reduction potentials of these ferrocene derivatives, thereby providing insight into their electronic structure and physicochemical properties.
Self‐Assembled Pd6 Open Cage with Triimidazole Walls and the Use of Its Confined Nanospace for Catalytic Knoevenagel‐ and Diels–Alder Reactions in Aqueous Medium
Authors: Samanta Dipak , Mukherjee Sandip , Patil Yogesh P. , Mukherjee Partha Sarathi 
Published: August 2012

AbstractThe two‐component self‐assembly of a 90° PdII acceptor and a triimidazole donor led to the formation of a water‐soluble semi‐cylindrical cage with a hydrophobic cavity, which was separately crystallized with hydrophilic‐ and hydrophobic guests. The parent cage was found to catalyze the Knoevenagel condensation reaction of a series of aromatic mono‐aldehydes with active methylene compounds, such as Meldrum′s acid or 1,3‐dimethylbarbituric acid. The confined hydrophobic nanospace within this cage was also used in the catalytic Diels–Alder reactions of 9‐hydroxymethylanthracene with N‐phenylmaleimide or N‐cyclohexylmaleimide.
ChemInform Abstract: Infrared Spectroscopic and Theoretical Investigations of the OUF2 and OThF2 Molecules with Triple Oxo Bond Character.
Authors: Gong Yu , Wang Xuefeng , Andrews Lester , Schloeder Tobias , Riedel Sebastian 
Published: August 2012

AbstractThe title molecules are prepared by reaction of OF2 molecules with laser ablated uranium and thorium atoms in solid argon and neon.
ChemInform Abstract: Optical and Structural Properties of Ni2+‐Doped Magnesium Gallate Polycrystalline Samples.
Authors: Costa G. K. B. , Sosman L. P. , Lopez A. , Cella N. , Barthem R. B. 
Published: August 2012

AbstractMg1‐xNixGa2O4 (x = 0.001, 0.005, 0.01) is synthesized by solid state reaction of MgO, Ga2O3, and Ni(OH)2 (1400 °C, 12 h).
ChemInform Abstract: Luminescence Properties of a New Greenish Blue Emitting Phosphor Na5Ca4(PO4)4F:Eu2+.
Authors: Xiao Haiyi , Xia Zhiguo , Liao Libing , Zhou Jun , Zhuang Jiaqing 
Published: August 2012

AbstractThe new title phosphor is synthesized by solid state reaction of a stoichiometric mixture of Na2CO3, NaF, CaCO3, (NH4)2HPO4, and Eu2O3 under CO reducing atmosphere (alumina crucible, 1000 °C, 4 h).
ChemInform Abstract: CsSnI3: Semiconductor or Metal? High Electrical Conductivity and Strong Near‐Infrared Photoluminescence from a Single Material. High Hole Mobility and Phase‐Transitions.
Authors: Chung In , Song Jung‐Hwan , Im Jino , Androulakis John , Malliakas Christos D. , Li Hao , Freeman Arthur J. , Kenney John T. , Kanatzidis Mercouri G. 
Published: August 2012

AbstractSingle‐crystal structures of three metastable black polymorphs of CsSnI3 are determined for the first time.
ChemInform Abstract: Systematic Evolution from Uranyl(VI) Phosphites to Uranium(IV) Phosphates.
Authors: Villa Eric M. , Marr Connor J. , Jouffret Laurent J. , Alekseev Evgeny V. , Depmeier Wulf , Albrecht‐Schmitt Thomas E. 
Published: August 2012

AbstractIn situ hydrothermal redox reactions of uranyl nitrate with phosphorous acid and alkali metal carbonates are explored and six new uranium phosphites, phosphates, and phosphite/phosphate mixed compounds are synthesized hydrothermally and one uranyl phosphite is obtained at room temperature.
ChemInform Abstract: Allylic C—H Activations Using Cu(II) 2‐Quinoxalinol Salen and tert‐Butyl Hydroperoxide.
Authors: Li Yuancheng , Lee Tae Bum , Wang Tanyu , Gamble Audrey V. , Gorden Anne E. V. 
Published: August 2012

AbstractThe Cu complex promotes the regioselective allylic oxidation of olefins giving various enones such as (II) and (V) in good to high yields.
ChemInform Abstract: Mild and Efficient α‐Chlorination of Carbonyl Compounds Using Ammonium Chloride and Oxone (2KHSO5·KHSO4·K2SO4 ).
Authors: Swamy Peraka , Kumar Macharla Arun , Reddy Marri Mahender , Narender Nama 
Published: August 2012

AbstractA simple protocol for the monochlorination of ketones (I) and (III) and 1,3‐dicarbonyl compounds (IX) and (XII) utilizing NH4Cl as a source of chlorine and Oxone as an oxidant in MeOH without any catalyst is presented.
ChemInform Abstract: Copper‐Catalyzed Di‐ and Trifluoromethylation of α,β‐Unsaturated Carboxylic Acids: A Protocol for Vinylic Fluoroalkylations.
Authors: He Zhengbiao , Luo Tao , Hu Mingyou , Cao Yanjing , Hu Jinbo 
Published: August 2012

AbstractThe copper reagent and the carboxylic acid group in the substrates play an important role in the new effective protocol for the title synthesis.
ChemInform Abstract: Oxidative Heck Arylation for the Stereoselective Synthesis of Tetrasubstituted Olefins Using Nitroxides as Oxidants.
Authors: He Zhiheng , Kirchberg Sylvia , Froehlich Roland , Studer Armido 
Published: August 2012

AbstractA mild and highly stereoselective sequential synthesis of the title compounds is developed.
ChemInform Abstract: Experimental and Theoretical Studies on the Nazarov Cyclization/Wagner—Meerwein Rearrangement Sequence.
Authors: Leboeuf David , Gandon Vincent , Ciesielski Jennifer , Frontier Alison J. 
Published: August 2012

AbstractHighly functionalized cyclopentenones are chemoselectively formed by the copper(II)‐mediated reaction of divinyl ketones.
ChemInform Abstract: An Efficient Synthetic Method for Allyl‐Epoxides via Allylation of α‐Haloketones or Esters with Allylmagnesium Bromide.
Authors: Fan Liyuan , Zhang Min , Zhang Songlin 
Published: August 2012

AbstractA new, simple, mild, and non‐metal‐catalyzed method for the title synthesis is developed.
ChemInform Abstract: Silver‐Mediated Oxidative C—H/C—H Functionalization: A Strategy to Construct Polysubstituted Furans.
Authors: He Chuan , Guo Sheng , Ke Jie , Hao Jing , Xu Huan , Chen Hongyi , Lei Aiwen 
Published: August 2012

AbstractAn extremely simple and atom‐economic method allows the preparation of trisubstituted furans from 1,3‐dicarbonyl compounds and aryl terminal alkynes in the presence of a stoichiometric amount of silver carbonate.
ChemInform Abstract: A Direct Catalytic Asymmetric Aldol Reaction of α‐Sulfanyl Lactones: Efficient Synthesis of SPT Inhibitors.
Authors: Takechi Sho , Yasuda Shigeo , Kumagai Naoya , Shibasaki Masakatsu 
Published: August 2012

AbstractThe scalable and not moisture sensitive [indicated by the reaction with the compound (IId)] title aldol reaction is developed.
ChemInform Abstract: Solvent‐Free Non‐Covalent Organocatalysis: Enantioselective Addition of Nitroalkanes to Alkylideneindolenines as a Flexible Gateway to Optically Active Tryptamine Derivatives.
Authors: Fochi Mariafrancesca , Gramigna Lucia , Mazzanti Andrea , Duce Sara , Fantini Stefano , Palmieri Alessandro , Petrini Marino , Bernardi Luca 
Published: August 2012

AbstractCinchona alkaloid‐catalyzed reaction of a diversity of in situ generated alkylideneindolenines with various nitroalkanes provides access towards polysubstituted nitroethylindoles, e.g. (III), (V), (VII), (IX) and (XI).
ChemInform Abstract: Trienamine Catalysis with 2,4‐Dienones: Development and Application in Asymmetric Diels—Alder Reactions.
Authors: Xiong Xiao‐Feng , Zhou Quan , Gu Jing , Dong Lin , Liu Tian‐Yu , Chen Ying‐Chun 
Published: August 2012

AbstractThe δ,δ‐substitution pattern of the 2,4‐dienones is necessary for the reaction.
ChemInform Abstract: L‐Proline‐Catalyzed Knoevenagel Condensation: A Facile, Green Synthesis of (E)‐Ethyl 2‐Cyano‐3‐(1H‐indol‐3‐yl)acrylates and (E)‐3‐(1H‐Indol‐3‐yl)acrylonitriles.
Authors: Venkatanarayana M. , Dubey P. K. 
Published: August 2012

AbstractAn environmentally friendly Knoevenagel condensation of indolecarboxaldehydes (I) with malonomononitrile (II) is achieved in ethanol using L‐proline as catalyst.
ChemInform Abstract: MCM‐41‐SO3H as a Highly Efficient Sulfonic Acid Nanoreactor for the Rapid and Green Synthesis of Some Novel Highly Substituted Imidazoles under Solvent‐Free Condition.
Authors: Mahdavinia Gholam Hossein , Amani Ali Mohammad , Sepehrian Hamid 
Published: August 2012

AbstractThe applied catalytic system can be recycled several times.
ChemInform Abstract: Achiral Counterion Control of Enantioselectivity in a Broensted Acid‐Catalyzed Iodolactonization.
Authors: Dobish Mark C. , Johnston Jeffrey N. 
Published: August 2012

AbstractThe combination of a chiral ammonium cation and the achiral triflimide anion present in catalyst (I) affords the highest enantioselectivity in the iodolactonization reaction of acid (IIa) compared to eight other combinations of the cation with achiral sulfonate counterions.
ChemInform Abstract: Palladium‐Catalyzed Cycloaddition of Alkynyl Aryl Ethers with Internal Alkynes via Selective ortho C—H Activation.
Authors: Minami Yasunori , Shiraishi Yuki , Yamada Kotomi , Hiyama Tamejiro 
Published: August 2012

AbstractSilylalkynyl aryl ethers and internal alkynes give under optimized conditions silylmethylidene‐substituted chromenes.
ChemInform Abstract: Modulating the Reactivity of Functionalized N,S‐Ketene Acetal in MCR: Selective Synthesis of Tetrahydropyridines and Thiochromeno[2,3‐b]pyridines via DABCO‐Catalyzed Tandem Annulation.
Authors: Wen Li‐Rong , Shi Yong‐Jie , Liu Guang‐Yuan , Li Ming 
Published: August 2012

AbstractA variety of pharmacologically interesting heterocyclic scaffolds is available via the three‐component process under optimized conditions A).
ChemInform Abstract: One Pot Synthesis of Medicinally Important cis‐2‐Methyl‐4‐amino Substituted‐1,2,3,4‐tetrahydroquinolines.
Authors: Kiran Kumar H. C. , Mahadevan K. M. , Prabhakara Varma P. , Srinivasa A. 
Published: August 2012

AbstractAntimony trichloride is an efficient catalyst for the synthesis of cis‐tetrahydroquinolines (III) and (V) by reaction of anilines (I) with N‐vinylcaprolactam (II) or N‐vinylcarbazole (IV), respectively.
ChemInform Abstract: A New Cascade Reaction: Concurrent Construction of Six and Five Membered Rings Leading to Novel Fused Quinazolinones.
Authors: Kumar K. Siva , Kumar P. Mahesh , Rao V. Sreenivasa , Jafar Ahamed A. , Meda Chandana Lakshmi T. , Kapavarapu R. , Parsa Kishore V. L. , Pal Manojit 
Published: August 2012

AbstractThe compounds (IV) are evaluated in vitro for their inhibitory potential against phosphodiesterase 4.
ChemInform Abstract: Stereocontrol in a Combined Allylic Azide Rearrangement and Intramolecular Schmidt Reaction.
Authors: Liu Ruzhang , Gutierrez Osvaldo , Tantillo Dean J. , Aube Jeffrey 
Published: August 2012

AbstractIn the presence of a Lewis acid, an interconverting set of isomeric allylic azides undergoes the Schmidt reaction to afford substituted lactams stereoselectively.
ChemInform Abstract: Enantioselective Synthesis of ε‐Lactones by Lipase‐Catalyzed Resolution.
Authors: Shimotori Yasutaka , Aoyama Masakazu , Tsukasa Hidetaka , Miyakoshi Tetsuo 
Published: August 2012

AbstractEnantioenriched lactone (V) is prepared by a sequence of lipase‐catalyzed kinetic resolution, alkaline hydrolysis and Novozym 435‐catalyzed lactonization.
ChemInform Abstract: Cross‐Coupling Between sp3‐Carbon and sp3‐Carbon Using a Diborylmethane Derivatives at Room Temperature.
Authors: Endo Kohei , Ohkubo Takahiro , Ishioka Takafumi , Shibata Takanori 
Published: August 2012

AbstractThe new and efficient method allows access to homoallylboronates and arylethylboronates.
ChemInform Abstract: Synthesis and Biological Evaluation of Oleanolic Acid Derivatives as Novel Inhibitors of Protein Tyrosine Phosphatase 1B.
Authors: Li Hui , Zou Hui , Gao Lixin , Liu Ting , Yang Fan , Li Jingya , Li Jia , Qiu Wen‐Wei , Tang Jie 
Published: August 2012

AbstractA series of novel oleanolic acid derivatives with five‐membered heterocyclic rings, fused at the C‐2, C‐3 positions, e.g. (II) and (V), as well some C‐ring modified derivatives, e.g. (I), (III) and (IV), is synthesized.
ChemInform Abstract: Synthesis and Biological Activity of Bi/tricyclic Azasugars Fused Thiazolidin‐4‐one and Thiazinan‐4‐one by Microwave‐Assisted Tandem Staudinger/Aza‐Wittig/Cyclization.
Authors: Li Xiaoliu , Qin Zhanbin , Yang Tianyu , Zhang Hongzhi , Wei Sinan , Li Chunxiao , Chen Hua , Meng Ming 
Published: August 2012

AbstractA series of novel bi‐ and tricyclic azasugars is synthesized.
Interim analysis of clinical trials based on urn models
Authors: ZHU Hongjian , HU Feifang 
Published: August 2012

AbstractClinical trials usually involve efficient and ethical objectives such as maximizing the power and minimizing the total failure number. Interim analysis is now a standard technique in practice to achieve these objectives. Randomized urn models have been extensively studied in the literature. In this paper, we propose to perform interim analysis on clinical trials based on urn models and study its properties. We show that the urn composition, allocation of patients and parameter estimators can be approximated by a joint Gaussian process. Consequently, sequential test statistics of the proposed procedure converge to a Brownian motion in distribution and the sequential test statistics asymptotically satisfy the canonical joint distribution defined in Jennison & Turnbull (Jennison & Turnbull 2000. Group Sequential Methods with Applications to Clinical Trials, Chapman and Hall/CRC). These results provide a solid foundation and open a door to perform the interim analysis on randomized clinical trials with urn models in practice. Furthermore, we demonstrate our proposal through examples and simulations by applying sequential monitoring and stochastic curtailment techniques. The Canadian Journal of Statistics 40: 550–568; 2012 © 2012 Statistical Society of Canada
Information borrowing methods for covariate‐adjusted ROC curve
Authors: GUAN Zhong , QIN Jing , ZHANG Biao 
Published: August 2012

AbstractIn medical diagnostic testing problems, the covariate adjusted receiver operating characteristic (ROC) curves have been discussed recently for achieving the best separation between disease and control. Due to various restrictions such as cost, the availability of patients, and ethical issues quite frequently only limited information is available. As a result, we are unlikely to have a large enough overall sample size to support reliable direct estimations of ROCs for all the underlying covariates of interest. For example, some genetic factors are less commonly observable compared with others. To get an accurate covariate adjusted ROC estimation, novel statistical methods are needed to effectively utilize the limited information. Therefore, it is desirable to use indirect estimates that borrow strength by employing values of the variables of interest from neighbouring covariates. In this paper we discuss two semiparametric exponential tilting models, where the density functions from different covariate levels share a common baseline density, and the parameters in the exponential tilting component reflect the difference among the covariates. With the proposed models, the estimated covariate adjusted ROC is much smoother and more efficient than the nonparametric counterpart without borrowing information from neighbouring covariates. A simulation study and a real data application are reported.The Canadian Journal of Statistics40: 569–587; 2012 © 2012 Statistical Society of Canada