bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gold(I)‐katalysierte diastereoselektive Hydroacylierung terminaler Alkine mit Glyoxalen
Authors: Shi Shuai , Wang Tao , Weingand Vanessa , Rudolph Matthias , Hashmi A. Stephen K. 
Published: December 2013

AbstractDie Reaktion eines α‐Ketoaldehyds und eines terminalen Alkins in Gegenwart von Piperidin und einer katalytischen Menge von AuCl liefert 1,2‐Dicarbonyl‐3‐ene, Produkte einer formalen Hydroacylierung der Dreifachbindung. Die Anwendungsbreite der Methode ist groß, verschiedene Arylsubstituenten an der Dicarbonyleinheit oder dem Alkin werden gut toleriert. Die Produkte können selektiv in Vinylchinoxaline überführt werden. Mechanistische Studien, inklusive Isotopenmarkierungsexperimente, weisen darauf hin, dass zunächst eine A3‐Umsetzung zu Propargylaminen führt und eine darauffolgende basenvermittelte Alkin/Allen‐Umlagerung und eine Hydrolyse der Enaminteilstruktur während der Aufarbeitung das formale Hydroacylierungsprodukt liefern.
PhI(OAc)2‐Mediated Radical Trifluoromethylation of Vinyl Azides with Me3SiCF3
Authors: Wang Yi‐Feng , Lonca Geoffroy Hervé , Chiba Shunsuke 
Published: December 2013

AbstractThe fluorine‐containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron‐withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)2‐mediated radical trifluoromethylation of vinyl azides with Me3SiCF3 to efficiently generate α‐trifluoromethyl azines. The resulting α‐trifluoromethyl azines were successfully transformed to valuable fluorine‐containing molecules such as α‐trifluoromethyl ketones, β‐trifluoromethyl amines, 5‐fluoropyrazoles, and trifluoroethyl isoquinolines.
Influence of the Absolute Configuration of NPE‐Caged Cytosine on DNA Single Base Pair Stability
Authors: Steinert Hannah S. , Schäfer Florian , Jonker Hendrik R. A. , Heckel Alexander , Schwalbe Harald 
Published: December 2013

AbstractPhotolabile protecting groups are a versatile tool to trigger reactions by light irradiation. In this study, we have investigated the influence of the absolute configuration of the 1‐(2‐nitrophenyl)ethyl (NPE) cage group on a 15‐base‐pair duplex DNA. Using UV melting, we determined the global stability of the unmodified and the selectively (S)‐ and (R)‐NPE‐modified DNA sequences, respectively. We observe a differently destabilizing effect for the two NPE stereoisomers on the global stability. Analysis of the temperature dependence of imino proton exchange rates measured by NMR spectroscopy reveals that this effect can be attributed to decreased base pair stabilities of the caged and the 3′‐neighbouring base pair, respectively. Furthermore, our NMR based structural models of the modified duplexes provide a structural basis for the distinct effect of the (S)‐ and the (R)‐NPE group.
Sb2Se3‐Sensitized Inorganic–Organic Heterojunction Solar Cells Fabricated Using a Single‐Source Precursor
Authors: Choi Yong Chan , Mandal Tarak Nath , Yang Woon Seok , Lee Yong Hui , Im Sang Hyuk , Noh Jun Hong , Seok Sang Il 
Published: December 2013

AbstractThe photovoltaic performance of Sb2Se3‐sensitized heterojunction solar cells, which were fabricated by a simple deposition of Sb2Se3 on mesoporous TiO2 by an approach that features multiple cycles of spin coating with a single‐source precursor solution and thermal decomposition, is reported. Poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7(2,1,3‐benzothioadiazole)] was used as the hole‐transporting material. The most efficient cell exhibited a short‐circuit current density of 22.3 mA cm−2, an open‐circuit voltage of 304.5 mV, and a fill factor of 47.2 %, yielding a power conversion efficiency of 3.21 % under standard test conditions (irradiation of 1000 W m−2, air mass=1.5 G). The results of this study imply that the developed approach has a high potential as a simple and effective route for the fabrication of efficient and inexpensive solar cells.
Combined Inhibitor Free‐Energy Landscape and Structural Analysis Reports on the Mannosidase Conformational Coordinate
Authors: Williams Rohan J. , Iglesias‐Fernández Javier , Stepper Judith , Jackson Adam , Thompson Andrew J. , Lowe Elisabeth C. , White Jonathan M. , Gilbert Harry J. , Rovira Carme , Davies Gideon J. , Williams Spencer J. 
Published: December 2013

AbstractMannosidases catalyze the hydrolysis of a diverse range of polysaccharides and glycoconjugates, and the various sequence‐based mannosidase families have evolved ingenious strategies to overcome the stereoelectronic challenges of mannoside chemistry. Using a combination of computational chemistry, inhibitor design and synthesis, and X‐ray crystallography of inhibitor/enzyme complexes, it is demonstrated that mannoimidazole‐type inhibitors are energetically poised to report faithfully on mannosidase transition‐state conformation, and provide direct evidence for the conformational itinerary used by diverse mannosidases, including β‐mannanases from families GH26 and GH113. Isofagomine‐type inhibitors are poor mimics of transition‐state conformation, owing to the high energy barriers that must be crossed to attain mechanistically relevant conformations, however, these sugar‐shaped heterocycles allow the acquisition of ternary complexes that span the active site, thus providing valuable insight into active‐site residues involved in substrate recognition.
Single‐Molecule Sensing of Environmental pH—an STM Break Junction and NEGF‐DFT Approach
Authors: Li Zhihai , Smeu Manuel , Afsari Sepideh , Xing Yangjun , Ratner Mark A. , Borguet Eric 
Published: December 2013

AbstractSensors play a significant role in the detection of toxic species and explosives, and in the remote control of chemical processes. In this work, we report a single‐molecule‐based pH switch/sensor that exploits the sensitivity of dye molecules to environmental pH to build metal–molecule–metal (m‐M‐m) devices using the scanning tunneling microscopy (STM) break junction technique. Dyes undergo pH‐induced electronic modulation due to reversible structural transformation between a conjugated and a nonconjugated form, resulting in a change in the HOMO–LUMO gap. The dye‐mediated m‐M‐m devices react to environmental pH with a high on/off ratio (≈100:1) of device conductivity. Density functional theory (DFT) calculations, carried out under the non‐equilibrium Green’s function (NEGF) framework, model charge transport through these molecules in the two possible forms and confirm that the HOMO–LUMO gap of dyes is nearly twice as large in the nonconjugated form as in the conjugated form.
Investigation of the Structure and Dynamics of the Capsid–Spacer Peptide 1–Nucleocapsid Fragment of the HIV‐1 Gag Polyprotein by Solution NMR Spectroscopy
Authors: Deshmukh Lalit , Ghirlando Rodolfo , Clore G. Marius 
Published: December 2013

AbstractStructural studies of HIV‐1 Gag, the primary structural polyprotein involved in retroviral assembly, have been challenging, owing to its flexibility and conformational heterogeneity. Using residual dipolar couplings, we show that the four structural units of the capsid (CA)–spacer peptide 1 (SP1)–nucleocapsid (NC) fragment of HIV‐1 Gag (namely, the N‐ and C‐terminal domains of capsid, and the N‐ and C‐terminal Zn knuckles of nucleocapsid) have the same structures as their individually isolated counterparts, and tumble semi‐independently of one another in the absence of nucleic acids. Nucleic acids bind exclusively to the nucleocapsid domain and fix the orientation of the two Zn knuckles relative to one another so that the nucleocapsid domain/nucleic acid complex behaves as a single structural unit. The low 15N–{1H} heteronuclear NOE values (≤0.4), the close to zero values for the residual dipolar couplings of the backbone amides, and minimal deviations from random‐coil chemical shifts for the C‐terminal tail of capsid and SP1, both in the absence and presence of nucleic acids, indicate that these regions are intrinsically disordered in the context of CA–SP1–NC.
Activation of a Photodissociative Ruthenium Complex by Triplet–Triplet Annihilation Upconversion in Liposomes
Authors: Askes Sven H. C. , Bahreman Azadeh , Bonnet Sylvestre 
Published: December 2013

AbstractLiposomes capable of generating photons of blue light in situ by triplet–triplet annihilation upconversion of either green or red light, were prepared. The red‐to‐blue upconverting liposomes were capable of triggering the photodissociation of ruthenium polypyridyl complexes from PEGylated liposomes using a clinical grade photodynamic therapy laser source (630 nm).
Cobalt Imidazolate Metal–Organic Frameworks Photosplit CO2 under Mild Reaction Conditions
Authors: Wang Sibo , Yao Wangshu , Lin Jinliang , Ding Zhengxin , Wang Xinchen 
Published: December 2013

AbstractMetal–organic frameworks (MOFs) have shown great promise for CO2 capture and storage. However, the operation of chemical redox functions of framework substances and organic CO2‐trapping entities which are spatially linked together to catalyze CO2 conversion has had much less attention. Reported herein is a cobalt‐containing zeolitic imidazolate framework (Co‐ZIF‐9) which serves as a robust MOF cocatalyst to reduce CO2 by cooperating with a ruthenium‐based photosensitizer. The catalytic turnover number of Co‐ZIF‐9 was about 450 within 2.5 hours under mild reaction conditions, while still keeping its original reactivity during prolonged operation.
Reversible Self‐Assembly of Terpyridine‐Functionalized Graphene Oxide for Energy Conversion
Authors: Song Shungang , Xue Yuhua , Feng Lianfang , Elbatal Hany , Wang Pingshan , Moorefield Charles N. , Newkome George R. , Dai Liming 
Published: December 2013

AbstractTerpyridine‐functionalized graphene oxides were prepared for self‐assembly into 3D architectures with various metal ions (e.g., Fe, Ru). The resulting electrode materials showed significantly improved electroactivities for efficient energy conversion and storage. They showed promise for application in the oxygen reduction reaction (ORR), photocurrent generation, and supercapacitance.
Efficacious Anticancer Drug Delivery Mediated by a pH‐Sensitive Self‐Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor
Authors: Moitra Parikshit , Kumar Krishan , Kondaiah Paturu , Bhattacharya Santanu 
Published: December 2013

AbstractWe present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy.
An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond
Authors: Nova Ainara , Suh Hee‐Won , Schmeier Timothy J. , Guard Louise M. , Eisenstein Odile , Hazari Nilay , Maseras Feliu 
Published: December 2013

AbstractPd and Ni dimers supported by PSiP ligands in which two hypervalent five‐coordinate Si atoms bridge the two metal centers are reported. Crystallographic characterization revealed a rare square‐pyramidal geometry at Si and an unusual asymmetric M2Si2 core (M=Pd or Ni). DFT calculations showed that the unusual structure of the core is also found in a model in which the phosphine and Si centers are not part of a pincer group, thus indicating that the observed geometry is not imposed by the PSiP ligand. NBO analysis showed that an asymmetric four‐center two‐electron (4c‐2e) bond stabilizes the hypervalent Si atoms in the M2Si2 core.
Gold(I)‐Catalyzed Diastereoselective Hydroacylation of Terminal Alkynes with Glyoxals
Authors: Shi Shuai , Wang Tao , Weingand Vanessa , Rudolph Matthias , Hashmi A. Stephen K. 
Published: December 2013

AbstractThe reaction of an α‐ketoaldehyde and a terminal alkyne in the presence of piperidine and a catalytic amount of AuCl delivers 1,2‐dicarbonyl‐3‐enes, products of the formal hydroacylation of the triple bond. The scope of the method is broad; different aryl substituents on the dicarbonyl unit and on the alkyne are well tolerated. The products can be transformed selectively into vinylquinoxalines. Mechanistic studies, including isotope‐labeling experiments, indicate that after an initial A3‐type conversion to propargylic amines, a subsequent base‐mediated alkyne‐to‐allene isomerization and a hydrolysis of the enamine substructure during the workup deliver the formal hydroacylation products.
Attenuation of the Aggregation and Neurotoxicity of Amyloid‐β Peptides by Catalytic Photooxygenation
Authors: Taniguchi Atsuhiko , Sasaki Daisuke , Shiohara Azusa , Iwatsubo Takeshi , Tomita Taisuke , Sohma Youhei , Kanai Motomu 
Published: December 2013

AbstractAlzheimer’s disease (AD), a progressive severe neurodegenerative disorder, is currently incurable, despite intensive efforts worldwide. Herein, we demonstrate that catalytic oxygenation of amyloid‐β peptides (Aβ) might be an effective approach to treat AD. Aβ1–42 was oxygenated under physiologically‐relevant conditions (pH 7.4, 37 °C) using a riboflavin catalyst and visible light irradiation, with modifications at the Tyr10, His13, His14, and Met35 residues. The oxygenated Aβ1–42 exhibited considerably lower aggregation potency and neurotoxicity compared with native Aβ. Photooxygenation of Aβ can be performed even in the presence of cells, by using a selective flavin catalyst attached to an Aβ‐binding peptide; the Aβ cytotoxicity was attenuated in this case as well. Furthermore, oxygenated Aβ1–42 inhibited the aggregation and cytotoxicity of native Aβ.
Effective Cancer Cell Killing by Hydrophobic Nanovoid‐Enhanced Cavitation under Safe Low‐Energy Ultrasound
Authors: Zhao Yang , Zhu Yingchun , Fu Jingke , Wang Lianzhou 
Published: December 2013

Abstractβ‐Cyclodextrin (β‐CD)‐capped mesoporous silica nanoparticles with hydrophobic internal nanovoids were prepared and used for effective cancer cell killing in synergistic combination with low‐energy ultrasound (≤1.0 W cm−2, 1 MHz). The water‐dispersible nanoparticles with hydrophobic internal nanovoids can be taken up by cancer cells and subsequently evoke a remarkable cavitation effect under irradiation with mild low‐energy ultrasound (≤1.0 W cm−2, 1 MHz). A significant cancer cell killing effect was observed in cancer cells and in a mouse xenograft tumor model treated with the nanoagents together with the low‐energy ultrasound, showing a distinct dependence on the concentration of nanoagents and ultrasound intensity. By contrast, an antitumor effect was not observed when either low‐energy ultrasound or nanoagents were applied alone. These findings are significant as the technique promises a safe, low‐cost, and effective treatment for cancer therapy.
Zum Zwischenstopp nach Ost‐Frankreich
Authors: Irsch Wilhelm 
Published: December 2013

AbstractDie Seenlandschaften des Lac du Der und des És̆tang de Lindre in Ostfrankreich bieten vielen Zugvögeln Rastmöglichkeiten. Besonders die im Herbst eintreffenden Kraniche halten Vogelbeobachter in Atem. Aber auch diverse Greif‐ und Wasservögel tragen ihren Teil dazu bei, dass diese Region ein lohnendes Ausflugsziel für Vogelkundler und Laien ist.
Wie man im Ausland gute Doktoranden finden kann
Authors: Nellen Wolfgang 
Published: December 2013

AbstractKleine Netzwerke zur Vermittlung ausländischer Wissenschaftler an deutsche Universitäten können die Anstrengungen des Deutschen Akademischen Austauschdienstes (DAAD) effektiv ergänzen, persönliche Ansprechpartner liefern und den deutschen Laboren sowie den ausländischen Studenten Enttäuschungen ersparen.
Quantification of carbamazepine and its 10,11‐epoxide metabolite in rat plasma by UPLC‐UV and application to pharmacokinetic study
Authors: Beig Avital , Dahan Arik 
Published: December 2013

ABSTRACTA rapid, selective and sensitive UPLC‐UV method was developed and validated for the quantitative analysis of carbamazepine and its epoxide metabolite in rat plasma. A relatively small volume of plasma sample (200 μL) is required for the described analytical method. The method includes simple protein precipitation, liquid–liquid extraction, evaporation, and reconstitution steps. Samples were separated on a Waters Acquity UPLC BEH C18 column (1.7 µm, 2.1 × 100 mm) with a gradient mobile phase consisted of 60:40 going to 40:60 (v/v) water–acetonitrile at a flow rate of 0.5 mL/min. The total run time was as low as 6 min, representing a significant improvement in comparison to existing methods. Excellent linearity (r2 > 0.999) was achieved over a wide concentration range. Close to complete recovery, short analysis time, high stability, accuracy, precision and reproducibility, and low limit of quantitation were demonstrated. Finally, we successfully applied this analytical method to a pre‐clinical oral pharmacokinetic study, revealing the plasma profiles of both carbamazepine and carbamazepine‐10,11‐epoxide following oral administration of carbamazepine to rats. The advantages demonstrated in this work make this analytical method both time‐ and cost‐efficient approach for drug and metabolite monitoring in the pre‐clinical/clinical laboratory. Copyright © 2013 John Wiley & Sons, Ltd.
President's page
Authors: Dillon Andrew 
Published: December 2013

AbstractEditor's SummaryIn his last column as ASIS&T president, Dillon recognizes the enduring work and continual progress of the Association through its transitions. Each year leaders with shared hopes and plans for the organization continue efforts started in previous years while adding new initiatives. An example is the name change to the Association for Information Science and Technology, the result of many leaders' deliberation and persistent effort to demonstrate global reach. Newer drives focus on active outreach to other parts of the world by seeking potential members through their native language and by committing to hold an Annual Meeting outside North America in the near future. In its ongoing effort to be recognized as a leading contributor to information science, the Association continues to enhance its web presence, build partnerships and help student members connect with chapters and progress as professionals. Progress continues, the result of good fortune and the valued contributions of many supporters.
Information science & technology and human rights: ASIS&T's participation in the AAAS science and human rights coalition*
Authors: Carbo Toni 
Published: December 2013

AbstractEditor's SummaryASIS&T core principles, including intellectual freedom, access to public information and balancing access with privacy, and the author's membership in the American Association for the Advancement of Science (AAAS) prompted ASIS&T to get involved in the AAAS Science and Human Rights Coalition. The Association joins 51 other science and engineering organizations and 70 individuals promoting human rights issues through the coalition, which was launched in 2009. Among the group's activities are communications to expand appreciation of the scientific and engineering communities' role in human rights efforts and developing teaching modules on the interaction of science and engineering with human rights. As ASIS&T representative to the coalition, Carbo invites member involvement and contributions to an updated, annotated bibliography of resources on information science and technology and human rights.
Terpenes from the Soft Corals of the Genus Sarcophyton: Chemistry and Biological Activities
Authors: Liang Lin‐Fu , Guo Yue‐Wei 
Published: December 2013

AbstractThis review covers structural diversity and biological activities of terpenes from soft corals of the genus of Sarcophyton, reported from 1995 to July, 2011. During this period, besides undefined species, 16 species of the genus Sarcophyton, from different geographical areas, had been chemically examined. Two hundred and five terpenes had been isolated from this genus, including eleven sesquiterpenes, 165 diterpenes, 29 biscembranoids, some of which had novel skeletons. They exhibited various biological features, such as antifeedant, anti‐inflammatory, antiviral, and antifouling activities.
Synthesis, Characterization, and Anti‐Amoebic Activity of N‐(Pyrimidin‐2‐yl)benzenesulfonamide Derivatives
Authors: Roouf Bhat Abdul , Arshad Mohammad , Ju Lee Eun , Pokharel Smritee , Choi Inho , Athar Fareeda 
Published: December 2013

AbstractA new series of N‐(pyrimidin‐2‐yl)benzenesulfonamide derivatives, 3a–3i and 4a–4i, was synthesized from pyrimidin‐2‐amines, 2a–2i, with the aim to explore their effects on in vitro growth of Entamoeba histolytica. The chemical structures of the compounds were elucidated by elemental analysis, FT‐IR, 1H‐ and 13C‐NMR, and ESI mass‐spectral data. In vitro anti‐amoebic activity was evaluated against HM1 : IMSS strain of Entamoeba histolytica. The IC50 values were calculated by using the double dilution method. The results were compared with the IC50 value of the standard drug ‘metronidazole’. The selected compounds were tested for their cytotoxic activities by cell‐viability assay using H9C2 cardiac myoblasts cell line, and the results indicated that all the compounds displayed remarkable >80% viabilities to a concentration of 100 μg/ml.
An Interactive SAR Approach to Discover Novel Hybrid Thieno Probes as Ligands for D2‐Like Receptors with Affinities in the Subnanomolar Range
Authors: Abdel‐Fattah Mohamed A. O. , Lehmann Jochen , Abadi Ashraf H. 
Published: December 2013

AbstractA series of [(phenylpiperazinyl)alkyl]‐isoindole‐1,3‐dione derivatives was synthesized to serve as probes for dopaminergic receptors. Among this series, compound 6a showed the highest affinity towards D4 and D3 receptors with Ki values in the low nanomolar range, and D2/D4‐ and D2/D3‐selectivity indices of 72 and 20, respectively. Optimization rounds were adopted and led to the D4‐selective ligand thiophene‐2‐carboxamide 9a with a Ki(D4) value of 0.62 nM, and to its butyl analog, 10a, with Ki(D4) and Ki(D3) values of 0.03 and 0.26 nM, respectively. Docking experiments revealed the importance of the unique D4 residue Arg186 in manipulating the ligands' D4‐subtype‐receptor selectivity.