bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteroaromatic Tosylates as Electrophiles in Regioselective Mizoroki–Heck‐Coupling Reactions with Electron‐Rich Olefins
Authors: Gøgsig Thomas M. , Lindhardt Anders T. , Dekhane Mouloud , Grouleff Julie , Skrydstrup Troels 
Published: May 2009

AbstractEasy and direct: Regioselective Mizoroki–Heck‐coupling reactions using heteroaromatic tosylates as electrophiles were achieved, thus providing direct and easy access to highly functionalized α‐heteroarylvinyl amides and ethers.magnified imageHeteroaromatic 2‐pyridyl tosylates were successfully applied as electrophiles in palladium(0)‐catalyzed Mizoroki–Heck‐coupling reactions to electron‐rich olefins with complete α‐regioselectivity. This protocol represents a general strategy for the application of pyridyl tosylates and mesylates in the Mizoroki–Heck coupling. The catalytic system also proved adaptable to changes in the heteroaromatic core as well as large‐scale applications. Finally, the synthetic utility of the functionalized α‐heteroarylvinyl amides was established providing straightforward access to highly functionalized heteroaromatic compounds including chiral benzylic amide derivatives.
Gold‐Catalyzed Stereocontrolled Synthesis of 2,3‐Bis(acetoxy)‐1,3‐dienes
Authors: Huang Xiaogen , de Haro Teresa , Nevado Cristina 
Published: May 2009

AbstractChange the ligand, change the stereochemistry: 2,3‐Bis(acetoxy)‐1,3‐dienes are obtained in a stereocontrolled manner by a novel tandem 1,2‐/1,2‐bis(acetoxy) rearrangement (see scheme, R1 and R2 are δ+ stabilizing). Upon stabilization of the reaction intermediates, the ligand attached to gold controls the stereochemistry of the alkene in the second acetate migration, that is, N‐heterocyclic carbenes (NHC) favor cis alkenes, whereas phosphine ligands selectively afford trans olefins.magnified image
Application of Copper(II)–Dipyridylphosphine Catalyst in the Asymmetric Hydrosilylation of Simple Ketones in Air
Authors: Zhang Xi‐Chang , Wu Yan , Yu Feng , Wu Fei‐Fei , Wu Jing , S. C. Chan Albert 
Published: May 2009

AbstractAsk a copper: A copper(II) salt/chiral dipyridylphosphine/PhSiH3 system (see scheme) acts as a very effective and practical catalyst for the asymmetric reduction of heteroaromatic and other types of ketones in air with good‐to‐excellent enantioselectivities (up to 94 %), giving many chiral alcohols that are intermediates for physiologically active compounds. Remarkable temperature effects were observed for some heteroaromatic ketones.magnified image
Nanostrukturierte Kern‐Schale‐Katalysatoren für PEM‐Brennstoffzellen – Hochaktive Materialien durch partielle Entlegierung
Authors: Strasser P. 
Published: May 2009

AbstractDie elektrochemische Umwandlung von Sauerstoff zu Wasser sowie ihre Umkehrreaktion gehören im Moment zu den größten Herausforderungen der Wissenschaft und Forschung zum Zwecke einer effizienten und nachhaltigen Nutzung elektrochemischer Energieumwandlungsprozesse basierend auf Brennstoffzellen oder der Elektrolyse von Wasser. Reines Platin – der am häufigsten verwendete Kathodenkatalysator für die Sauerstoffreduktion in Brennstoffzellen – ist teuer und nicht ausreichend aktiv und stabil. Vielversprechend ist ein neues Katalysatorkonzept basierend auf einem sehr Pt armen nanostrukturierten Kern‐Schale‐Prinzip. Durch selektives partielles Entlegieren, d. h. elektrochemische Entfernung von unedlen Metallatomen aus der Oberfläche einer nichtedelmetallreichen Pt‐Legierung („Dealloying”︁), wird eine Pt reiche Schale auf einem nichtedelmetallreichen Kern von definierbarer Dicke gebildet, die eine gezielte Steuerbarkeit von katalytischer Aktivität ermöglicht. Eine Reduzierung der Pt‐Menge in der Zellkathode um mehr als 80 % ist dabei möglich.
Rabs and cancer cell motility
Authors: Tang Bor Luen , Ng Ee Ling 
Published: May 2009

AbstractThe Rab family of small GTPases functions in regulating vesicular transport in all eukaryotes. In the past few years, several important reports have linked some members of the Rab family to intriguing mechanistic aspects of cancer cell migration and invasiveness. Rab5 and Rab21 associate with α‐integrin subunits and modulate their endosomal traffic and subcellular localization. Expression of the latter enhances adhesion and migration of certain cancer cell types. Rab25 has been functionally linked to tumor progression and the invasiveness of some epithelial cancers. Rab25 promotes invasive migration of cells in three‐dimensional microenvironments by associating with α5β1 integrin, and directing its recycling to dynamic ruffling protrusions at the migrating cell front. Acting directly, or through its effector, the Rab‐coupling protein, Rab25 could potentially engage both integrin and epidermal growth factor receptor and enhance their oncogenic recycling and signaling. Tumor invasiveness may also be modulated by Rab8‐mediated exocytic traffic of MT1‐matrix metalloproteinase, with the latter's activity likely influenced by interaction with the mammalian suppressor of Sec4 (Mss4), a Rab8 guanine nucleotide exchange factor, and integrin. We discuss highlights in the recent literature that point towards a role for Rab‐mediated membrane traffic in cancer cell migration and invasion. Cell Motil. Cytoskeleton 2009. © 2009 Wiley‐Liss, Inc.
Spin–Spin Coupling Constants Transmitted through IrH⋅⋅⋅HN Dihydrogen Bonds
Authors: Olejniczak Malgorzata , Pecul Magdalena 
Published: May 2009

AbstractRelativity matters: Calculations of NMR shielding tensors and spin–spin coupling constants transmitted through IrH⋅⋅⋅HN dihydrogen bonds are presented. The picture shows one of the simplified models employed. It is shown that the spin–orbit relativistic effects influence the NMR shielding constants far more than the spin–spin coupling constants.magnified imageWe present calculations of NMR shielding tensors and spin–spin coupling constants transmitted through IrH⋅⋅⋅HN dihydrogen bonds. For this purpose, three six‐coordinated complexes of iridium have been selected as models of heavy metal complexes and their NMR properties have been calculated within the DFT‐ZORA (density functional theory zeroth‐order regular approximation) methodology. The influence of intramolecular interactions between hydrogen atoms from IrH3 and NH2 groups (including both single dihydrogen bonding and bifurcated hydrogen bonding) on the NMR properties is discussed and the results are compared with the experimental observations. In complexes where dihydrogen bonding occurs, the calculated value of “through‐space” 1hJ(HaHb) is in the range 1.6–7.9 Hz [depending on the model, but with R(HaHb)<2.0 Å], while the experimental values are 2–5 Hz for similar HaHb distances. The 2hJ(NH) coupling is also sizeable, ranging from approximately −5.1 Hz for dihydrogen bonds of 2 Å up to −7.1 Hz for very short (1.6 Å) dihydrogen bonds, and should therefore be experimentally accessible when using 15N‐labelled compounds. The dihydrogen‐bond transmitted spin–spin coupling constants 1hJ(HH) and 2hJ(NH) and the shielding tensor of the Ha atom are the most sensitive probes of the HaHb distance, which potentially makes them attractive tools to determine the structure of molecules. The main conclusions are qualitatively similar to those drawn from nonrelativistic calculations in small inorganic complexes, and the spin–orbit relativistic effects influence the NMR shielding constants far more than the spin–spin coupling constants.
Security and delay issues in SIP systems
Authors: Callegari Christian , Garroppo Rosario G. , Giordano Stefano , Pagano Michele 
Published: May 2009

AbstractThe deployment of multimedia over IP (MoIP), and in particular voice over IP services, requires to solve new security issues they introduce, before completely exploiting the great opportunities they offer to telecommunication market. Furthermore, the implementation of various security measures can cause a marked deterioration in quality of service, which is fundamental to the operation of an MoIP network that meets users' quality expectations. In particular, because of the time‐critical nature of MoIP and its low tolerance for disruption and packet loss, many security measures implemented in traditional data networks are simply not applicable in their current form. This paper presents an analysis of the security options of Session Initiation Protocol‐ (SIP)‐based MoIP architecture aimed at evaluating their impact on delay. In particular, each security option is analyzed in terms of clock cycles needed to perform the related operations. This parameter could be used to estimate the delay introduced by the security mechanisms. Moreover the paper proposes a rigorous definition of five security profiles, which provide different levels of security to a MoIP system. Copyright © 2009 John Wiley & Sons, Ltd.
Cell survival and apoptosis‐related molecules in cancer cells in effusions: A comprehensive review
Authors: Kleinberg Lilach , Davidson Ben 
Published: May 2009

AbstractSpreading of cancer cells to effusions is a manifestation of advanced disease, for which the chances of achieving cure using conventional treatment are low. This emphasizes both the importance of improving early detection and the need for developing targeted therapy modes. Such approaches should be based on characterization of the antiapoptotic, survival and drug resistance mechanisms of the metastatic cells in addition to analysis of the primary tumor. This review presents current knowledge regarding the expression and clinical role of cell survival and apoptosis‐related molecules in nonhematological cancers in effusions. Differences in the anatomic site‐related expression and clinical role of these proteins are additionally discussed. The data presented highlight the complexity of the multiple molecular pathways that mediate tumor cell survival within the serosal cavities. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.
The use of thrombelastography to determine coagulation status in severe anorexia nervosa: A case series
Authors: Gaudiani Jennifer L. , Kashuk Jeffry L. , Chu Eugene S. , Narayanan Vignesh , Mehler Philip S. 
Published: May 2009

AbstractObjective:Hospitalized patients with severe anorexia nervosa (AN) frequently have a complex coagulation profile, with elements of hypocoagulability‐thrombocytopenia and elevated international normalized ratio (INR) and elements of hypercoagulability‐usually manifested as immobility, which is either due to their marked weakness or from enforced degrees of bed rest to minimize energy expenditure. Hospitalized medical patients have been shown to have appropriate prophylaxis for venous thromboembolic (VTE) disease in only 40% of cases.Method:A simple test that could evaluate the overall coagulation profile of these patients would help guide appropriate VTE prophylaxis. The thrombelastogram is a blood test that evaluates the full dynamic process of hemostasis.Results:The study of patients did not reveal evidence of being hypocoagulable and thus should be considered for VTE prophylaxis.Discussion:We report on three cases of young women with severe AN and weakness, hospitalized for closely monitored refeeding, in whom the thromboelastogram was used to evaluate the coagulation status of the patient and assist in guiding therapy. © 2009 by Wiley Periodicals, Inc. Int J Eat Disord 2010
A‐Frame‐Containing Organometallic Oligomers Constructed From Homo‐ and Heterobimetallic M(μ‐dppm)2M′ (M/M′ = Pd, Pt) Building Blocks
Authors: Clément Sébastien , Aly Shawkat M. , Husson Jérôme , Fortin Daniel , Strohmann Carsten , Knorr Michael , Guyard Laurent , Abd‐El‐Aziz Alaa S. , Harvey Pierre D. 
Published: May 2009

AbstractThe homo‐ and heterodinuclear complexes XM(μ‐dppm)2M′X (M = M′ = Pd, X = Cl 1a; M = M′ = Pd, X = I 1b; M = Pd, M′ = Pt, X = Cl 2a; M = Pd, M′ = Pt, X = I 2b; M = M′ = Pt, X = Cl 3a; M = M′ = Pt, X = I 3b) react with the diisocyanide ligand 1,2‐bis(2‐isocyanophenoxy)ethane (diNC) or the more soluble 1,2‐bis(2‐isocyano‐4‐tert‐butylphenoxy)ethane (tBudiNC) in a 1:1 ratio to provide the thermally stable polymeric materials 4–9 {[XM(μ‐dppm)2M′(μ‐CN‐C6H3R‐2‐OCH2CH2O‐2‐C6H3R‐NC)]X}n (M = M′ = Pd, R = H, X = Cl 4a, I 4b; R = tBu, X = Cl 7; M = M′ = Pt, R = H, X = Cl 5a, I 5b; R = tBu, X = Cl 8; M = Pd, M′ = Pt, R = H, X = Cl 6a, I 6b; R = tBu, X = Cl 9). These A‐frame‐containing materials have been characterized in solution or in the solid state by 31P NMR (MAS) spectroscopy, elemental analysis, MALDI‐TOF, DSC, TGA, IR and T1/NOE [31P NMR spin‐lattice relaxation time and nuclear Overhauser enhancement constant (NOE) measurements]. The IR, Raman [ν(CN) bridging vs. terminal] and NMR spectroscopic data reveal the presence of an A‐frame structure for these new materials. Evidence of an oligomer (including at least two units, determined by T1/NOE experiments) – polymer equilibrium in solution was obtained at room temperature. These polymers are luminescent (phosphorescence) at 77 K in solution and in the solid state, exhibiting broad emission bands in the 500–800 nm range. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis, Structures, and Excited‐State Geometries of Alkynylgold(I) Complexes
Authors: Gao Lei , Partyka David V. , Updegraff James B. , Deligonul Nihal , Gray Thomas G. 
Published: May 2009

AbstractA series of phosphane‐ and (N‐heterocyclic carbene)gold(I) complexes were prepared by deprotonation of terminal alkyne precursors and reaction with the corresponding gold(I) chlorides. Some ten new compounds are reported; these are characterized by multinuclear NMR, optical spectroscopy, and elemental analysis. Crystallographic characterization is reported for five complexes. Organogold species bearing conjugated aryl substituents on the alkynyl ligand are luminescent. Density‐functional theory calculations on a model complex suggest that emission and the first several absorption transitions result from excited states dominated by the arylacetylide ligand. Excited‐state geometry optimization finds that the lowest‐energy triplet state bears linear, two‐coordinate gold(I) with a miniscule lengthening of the alkynyl carbon–carbon bond. An unusual triplet excited state having a bent geometry at gold lies at higher energy in arylacetylide complexes. For the model terminal acetylideMe3PAuC≡CH, the calculations find this bent state to be the lowest‐energy triplet.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Spicochalasin A and New Aspochalasins from the Marine‐Derived Fungus Spicaria elegans
Authors: Lin Zhenjian , Zhu Tianjiao , Wei Hongjuan , Zhang Guojian , Wang Hui , Gu Qianqun 
Published: May 2009

AbstractDifferent culture conditions directed by the OSMAC (one strain‐many compounds) approach drastically modified the metabolites of the fungus Spicaria elegans, which yielded the novel spicochalasin A (1), five new aspochalasins M–Q (2–6), and two known aspochalasins (7 and 8). The gross structures of 1–6 were elucidated by 1D and 2D NMR and MS methods, and their absolute configurations were determined by X‐ray diffraction and the Mosher ester method. Spicochalasin A (1) has a unique pentacyclic system and was found to be moderately cytotoxic towards human leukemic HL‐60 cells with an IC50 value of 19.9 μM.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Double Methylenecyclopentane Annulation of Succinimides: Easy Access to 3,7‐Dioxobicyclo[3.3.0]octane‐1,5‐dicarboximides
Authors: Camps Pelayo , Fernández José A. , Rull Jordi , Vázquez Santiago 
Published: May 2009

AbstractN‐Alkylsuccinimides reacted with excess of LHMDS and 3‐chloro‐2‐(chloromethyl)‐1‐propene to give in medium yieldsN‐alkyl‐3,7‐dimethylenebicyclo[3.3.0]octane‐1,5‐dicarboximides, which were ozonized to the corresponding 3,7‐dioxobicyclo[3.3.0]octane‐1,5‐dicarboximides. When these alkylations were carried out by using LDA as the base, cis‐N‐alkyl‐4‐methylenecyclopentane‐1,2‐dicarboximides were mainly obtained, in spite of using excess of both base and alkylating agent.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Click Multivalent Homogeneous Neoglycoconjugates – Synthesis and Evaluation of Their Binding Affinities (Eur. J. Org. Chem. 15/2009)
Authors: Perez‐Balderas Francisco , Morales‐Sanfrutos Julia , Hernandez‐Mateo Fernando , Isac‐García Joaquín , Santoyo‐Gonzalez Francisco 
Published: May 2009

AbstractThe cover picture shows two copper(I) click‐based strategies for accessing multivalent neoglyconjugates by the coupling of complementary functionalized scaffolds and sugar derivatives. The methodology allows the easy preparation of structurally diverse homogeneous neoglycoconjugates from which the influence of the structural parameters in the binding affinities toward Concanavalin A could be evaluated. Details are discussed in the article by F. Santoyo‐Gonzalez et al. on page 2441ff.
Simultaneous Differential Pulse Voltammetric Determination of Sulfamethoxazole and Trimethoprim on a Boron‐Doped Diamond Electrode
Authors: Andrade Leonardo S. , Rocha‐Filho Romeu C. , Cass Quezia B. , Fatibello‐Filho Orlando 
Published: May 2009

AbstractThe performance of hydrogen‐ (HT) and oxygen‐terminated (OT) boron‐doped diamond (BDD) electrodes (electrochemically pretreated) on the simultaneous differential pulse voltammetric determination of sulfamethoxazole and trimethoprim in pharmaceutical products is presented. Under the optimum analytical experimental conditions, the HT‐BDD electrode presented two well‐defined oxidation peaks at 920 and 1100 mV vs. Ag/AgCl for sulfamethoxazole and trimethoprim, respectively. On the other hand, when the OT‐BDD electrode was used, the sulfamethoxazole oxidation current peak was decreased twenty fold. The calculated LOD values for sulfamethoxazole and trimethoprim using the HT‐BDD electrode were 3.65 μg L−1 and 3.92 μg L−1, respectively. The results obtained in the simultaneous determination of sulfamethoxazole and trimethoprim in three different commercial formulations were similar to those obtained using a standard HPLC method at 95% confidence level.
DNA Aptamers that Bind to PQQGDH as an Electrochemical Labeling Tool
Authors: Osawa Yuko , Takase Madoka , Sode Koji , Ikebukuro Kazunori 
Published: May 2009

AbstractWe screened DNA aptamers that bind to pyrroquinoline quinone glucose dehydrogenase (PQQGDH) for the development of an electrochemical labeling tool. PQQGDH is an excellent enzyme for the signal amplification of biosensors. We focused on DNA aptamers as labeling agents and tried to select those DNA aptamers that bind to PQQGDH without affecting its enzymatic activity. After 7 rounds of screening, one aptamer was obtained: ‘PGa4’. It bound to PQQGDH with specificity and showed no effect on the glucose dehydrogenase (GDH) activity. Moreover, beads labeled with PQQGDH via PGa4 generated an electrical current upon glucose addition. Therefore, we believe that the PGa4 aptamer against PQQGDH may become a powerful labeling tool for electrochemical biosensors.
Electrochemistry and Adsorptive Stripping Voltammetric Determination of Amoxicillin on a Multiwalled Carbon Nanotubes Modified Glassy Carbon Electrode
Authors: Rezaei Behzad , Damiri Sajjad 
Published: May 2009

AbstractThe study of electrochemical behavior of amoxicillin (AMX), a β‐lactam antibiotic, is described on a multiwalled carbon nanotubes (MWCNTs) modified electrode by electrochemical impedance spectroscopy (EIS) and adsorptive stripping voltammetry for sensitive determination of AMX in pharmaceutical and human urine samples within a wide pH range from 2.0 to 10.0. Also, studies by Fe2O3 nanoparticles modified carbon paste electrode show that iron oxide impurities in the MWCNTs are not active sites for sensing of amoxicillin. Under optimized conditions, the oxidation peak has two linear dynamic ranges of 0.6–8.0 and 10.0–80.0 μM with a detection limit of 0.2 μM and a precision of <4%.
Maximum penetration level of distributed generation with safety criteria
Authors: Van Thong Vu , Belmans Ronnie 
Published: May 2009

AbstractMany recent blackouts might raise a concern on how the introduction of distributed generation (DG) (fromrenewableor non‐renewable energy resources) into the network influences its secure operation in terms of dynamic performance. The anti‐islanding criteria of DG may harm the secure operation of the power system. In this paper, the maximum penetration level of DG is determined using dynamic studies. Tested systems are applied to verify a proposed methodology. The results show that the protection settings have an influence the maximum penetration of DG and the system secure operation. Copyright © 2009 John Wiley & Sons, Ltd.
Understanding the partial discharge activity of conducting particles in GIS under DC voltages using the UHF technique
Authors: Sarathi R. , Umamaheswari R. 
Published: May 2009

AbstractThe major cause of failure of DC‐GIS is due to presence of foreign particles causing partial discharges in the insulation structure. The particle movement in gas insulated system (GIS) radiates electromagnetic waves and the bandwidth of the signal lies in the range 1–2 GHz. Increase in applied DC voltage/pressure has not altered the frequency content of the ultra high frequency (UHF) signal generated due to partial discharge formed by particle movement. The UHF sensor could recognize the breakdown of sulfur‐hexa‐fluoride (SF6) gas under DC and Lightning impulse voltages and the frequency content of the signal captured by the UHF sensor lies up to 500 MHz. Mounting UHF sensor in GIS could allow one to classify internal partial discharges from breakdown, at the time of testing/during operation. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of fermentation on free and bound volatile compounds of orange juice
Authors: Fan Gang , Lu Wei , Yao Xiaolin , Zhang Yun , Wang Kexing , Pan Siyi 
Published: May 2009

AbstractAroma is one of the most important attributes of orange wine quality. The volatile compounds in orange wine mainly derive from oranges, yeast fermentation and compounds released from odourless glycosidic precursors present in the orange. In this study, free volatile compounds in orange juice and wine made from Citrus sinensis (L). Osbeck cv. Washington Sanguine were analysed by SPME‐GC–MS. Bound fractions were isolated and extracted with methanol and Amberlite XAD‐2 resin and then hydrolysed by almond β‐glucosidase. Totals of 31 and 19 free volatiles were identified in orange juice and wines, respectively. Terpenes were the most abundant compounds in orange juice, while esters were quantitatively the dominant group in orange wine and most of them were compounds newly formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate. In total, 11 and three released bound volatiles were found in orange juice and wine, respectively, and most of them were not found in free form. Only ethyl 3‐hydroxyhexanoate and cis‐carveol were found present in both the free and bound forms of orange juice. Copyright © 2009 John Wiley & Sons, Ltd.