bluuebunny/crossref_metadata_2025_split huggingface dataset:
How to Make 8,1,2‐closo‐MC2B9 Metallacarboranes
Authors: Man Wing Y. , Zlatogorsky Sergey , Tricas Hugo , Ellis David , Rosair Georgina M. , Welch Alan J. 
Published: September 2014

AbstractThree examples of the rare 8,1,2‐closo‐MC2B9 isomeric form of an icosahedral metallacarborane have been isolated as unexpected trace products in reactions. Seeking to understand how these were formed we considered both the nature of the reactions that were being undertaken and the nature of the coproducts. This led us to propose a mechanism for the formation of the 8,1,2‐closo‐MC2B9 species. The mechanism was then tested, leading to the first deliberate synthesis of an example of this isomer. Thus, deboronation of 4‐(η‐C5H5)‐4,1,8‐closo‐CoC2B10H12 selectively removes the B5 vertex to yield the dianion [nido‐(η‐C5H5)CoC2B9H11]2−, oxidative closure of which affords 8‐(η‐C5H5)‐8,1,2‐closo‐CoC2B9H11 in moderate yield.
Platinum(II)–Gadolinium(III) Complexes as Potential Single‐Molecular Theranostic Agents for Cancer Treatment
Authors: Zhu Zhenzhu , Wang Xiaoyong , Li Tuanjie , Aime Silvio , Sadler Peter J. , Guo Zijian 
Published: September 2014

AbstractTheranostic agents are emerging multifunctional molecules capable of simultaneous therapy and diagnosis of diseases. We found that platinum(II)–gadolinium(III) complexes with the formula [{Pt(NH3)2Cl}2GdL](NO3)2 possess such properties. The Gd center is stable in solution and the cytoplasm, whereas the Pt centers undergo ligand substitution in cancer cells. The Pt units interact with DNA and significantly promote the cellular uptake of Gd complexes. The cytotoxicity of the Pt–Gd complexes is comparable to that of cisplatin at high concentrations (≥0.1 mM), and their proton relaxivity is higher than that of the commercial magnetic resonance imaging (MRI) contrast agent Gd–DTPA. T1‐weighted MRI on B6 mice demonstrated that these complexes can reveal the accumulation of platinum drugs in vivo. Their cytotoxicity and imaging capabilities make the Pt–Gd complexes promising theranostic agents for cancer treatment.
Stabilization of Palladium Catalysts for the Heck Reaction by Support Functionalization and Solvent Selection
Authors: Oliveira Rafael L. , Hooijmans Jasper B. F. , E. de Jongh Petra , Klein Gebbink Robertus J. M. , P. de Jong Krijn 
Published: September 2014

AbstractPd nanoparticles were synthesized on nonfunctionalized and functionalized SBA‐15 grafted with thiol or amine groups. The resulting materials were used as catalysts to study the influence of these functional groups for a similar Pd particle size of approximately 2 nm on the Heck reaction that uses iodide substrates. The nonfunctionalized catalysts lost their activity quickly because of Pd leaching and particle growth. However, if a mixed solvent that consisted of toluene and DMF was used and thiol groups were grafted on SBA‐15, we were able to reduce the Pd leaching and particle growth to thus obtain a more stable catalyst in which an important role of the ligands was to recapture Pd. However, heterogeneity tests, such as a hot filtration test and poisoning experiments, gave a strong indication that Pd still leached from the support and that homogeneous Pd species were mainly responsible for the activity. Pd on S‐functionalized SBA‐15 was able to catalyze the Heck reaction using different substrates to achieve good activity and selectivity in most cases.
Efficient Sensing of Explosives by Using Fluorescent Nonporous Films of Oligophenyleneethynylene Derivatives Thanks to Optimal Structure Orientation and Exciton Migration
Authors: Caron Thomas , Pasquinet Eric , van der Lee Arie , Pansu Robert B. , Rouessac Vincent , Clavaguera Simon , Bouhadid Myriam , Serein‐Spirau Françoise , Lère‐Porte Jean‐Pierre , Montméat Pierre 
Published: September 2014

AbstractThe fluorescence of thin films of a diimine‐substituted phenyleneethynylene compound can be efficiently quenched by nitroaromatic vapors, which is not the case for the unsubstituted parent compound. Thin‐film porosity is usually considered to be an essential factor for efficient quenching, but in the present case the origin of the quenching is completely different, as both films are nonporous and hermetic to 2,4‐dinitrotoluene (DNT) molecules. The molecular organization in the two crystallized thin films offers a low level of π stacking for both compounds, but the orientation of the phenylenethynylene fluorophore differs markedly with respect to the surface of the films. For the substituted compound, the fluorophore is almost parallel to the surface, thus making it readily available to molecules of a nitroaromatic quencher. This rationale is also observed in the case of a related compound bearing methoxy side chains instead of the long octyloxy moieties. Fluorescence‐lifetime experiments show that the efficient quenching process in the nonporous crystallized films of the substituted compound is due to a fast (<70 ps) diffusion of excitons from the bulk of the film toward the surface where they are quenched, thus providing evidence of antenna effects.
Organic–Inorganic Azafullerene‐Gold C59N‐Au Nanohybrid: Synthesis, Characterization, and Properties
Authors: Rotas Georgios , Niemi Marja , Tkachenko Nikolai V. , Zhao Sihan , Shinohara Hisanori , Tagmatarchis Nikos 
Published: September 2014

AbstractAzafullerene (C59N) was functionalized using a Mannich‐type reaction and then subsequently condensed with lipoic acid to yield dithiolane‐modified C59N. In the following step, the extended dithiolane moiety from the C59N core was utilized to decorate the azafullerene sphere with gold nanoparticles (Au NPs). The latter were initially stabilized with dodecanothiol (DT⋅Au) and then integrated on azafullerene through a ligand exchange reaction with the dithiolane‐functionalized C59N to produce the C59N/DT⋅Au nanohybrid. The nanohybrid was fully characterized by spectroscopy and microscopy, revealing the formation of spherical nanoparticles with a diameter in the range of 2–5 nm, as imaged by HR‐TEM. In the electronic absorption spectrum of C59N/DT⋅Au nanohybrid, the characteristic surface plasmon band (SPB) of Au NPs was observed, however, it was redshifted compared with that of DT⋅Au. The redshift of the SPB is indicative of closer interparticle proximity of Au NPs, in accordance with the formation of aggregated NPs as observed by TEM, in C59N/DT⋅Au nanohybrid. Excited‐state interactions in C59N/DT⋅Au were probed by photoluminescence assays. It was found that the weak emission of C59N at 819 nm was blueshifted by 14 nm in C59N/DT⋅Au, but was stronger in intensity, thus suggesting energy transfer to C59N, within the organic–inorganic C59N/DT⋅Au nanohybrid. Finally, with the aid of pump–probe measurements and transient absorption spectroscopy, the formation of the singlet excited state of C59N was identified.
Photoinduced Electron Transfer within a Zinc Porphyrin–Cyclobis(paraquat‐p‐phenylene) Donor–Acceptor Dyad
Authors: Fathalla Maher , Barnes Jonathan C. , Young Ryan M. , Hartlieb Karel J. , Dyar Scott M. , Eaton Samuel W. , Sarjeant Amy A. , Co Dick T. , Wasielewski Michael R. , Stoddart J. Fraser 
Published: September 2014

AbstractUnderstanding the mechanism of efficient photoinduced electron‐transfer processes is essential for developing molecular systems for artificial photosynthesis. Towards this goal, we describe the synthesis of a donor–acceptor dyad comprising a zinc porphyrin donor and a tetracationic cyclobis(paraquat‐p‐phenylene) (CBPQT4+) acceptor. The X‐ray crystal structure of the dyad reveals the formation of a dimeric motif through the intermolecular coordination between the triazole nitrogen and the central Zn metal of two adjacent units of the dyad. Photoinduced electron transfer within the dyad in MeCN was investigated by femtosecond and nanosecond transient absorption spectroscopy, as well as by transient EPR spectroscopy. Photoexcitation of the dyad produced a weakly coupled ZnP+.–CBPQT3+. spin‐correlated radical‐ion pair having a τ=146 ns lifetime and a spin–spin exchange interaction of only 0.23 mT. The long radical‐ion‐pair lifetime results from weak donor–acceptor electronic coupling as a consequence of having nine bonds between the donor and the acceptor, and the reduction in reorganization energy for electron transfer caused by charge dispersal over both paraquat units within CBPQT3+..
Potent Anticancer Activity and Possible Low Toxicity of Platinum(II) Complexes with Functionalized 1,1‐Cyclobutanedicarboxylate as a Leaving Ligand
Authors: Zhao Jian , Gou Shaohua , Liu Fengfan 
Published: September 2014

AbstractTwo platinum(II) complexes, DN603 and DN604, were designed and prepared by using 3‐oxocyclobutane‐1,1‐dicarboxylate as a ligand. The compounds were prepared according to the concept that incorporation of a functionalized moiety in the leaving ligand that did not affect its coordination bonding to the metal atom would play a key role in the anticancer activity of the resulting platinum complex. The newly prepared compounds were found to show potent in vitro anticancer activity comparable to cisplatin and oxaliplatin; especially DN604, which exhibited low acute toxicity similar to carboplatin, and presented acceptable solubility and stability in water. Chemical and biological results indicated that the functionalized moiety, uncoordinated, led to potent anticancer activity and low apparent toxicity of the platinum complexes by affecting the kinetic properties of the compounds.
Impact of Clinical and Therapeutic Factors on Incident Cardiovascular and Cerebrovascular Events in a Population‐Based Cohort of HIV‐Infected and Non–HIV‐Infected Adults
Authors: Tripathi Avnish , Liese Angela D. , Winniford Michael D. , Jerrell Jeanette M. , Albrecht Helmut , Rizvi Ali A. , Zhang Jiajia , Duffus Wayne A. 
Published: September 2014

AbstractBackgroundCardiovascular and cerebrovascular (CVD) events/diseases are a common cause of non–acquired immunodeficiency syndrome (AIDS)‐related mortality in the aging human immunodeficiency virus (HIV)‐infected population. The incidence rate and clinical correlates of CVD in people living with HIV/AIDS compared to the general population warrants further investigation.HypothesisHIV/AIDS is associated with increased risk CVD compared to general population.MethodsCVD events in a matched cohort of HIV‐infected and non–HIV‐infected adults, ≥18 years old, served through the South Carolina Medicaid program during 1994 to 2011 were examined using time‐dependent proportional hazards regression and marginal structural modeling.ResultsA retrospective cohort of 13 632 adults was followed longitudinally for an average of 51 months. The adjusted hazard ratio (aHR) of incident CVD events was higher among HIV‐infected individuals exposed to combination antiretroviral therapy (cART) (aHR = 1.15) compared to the non–HIV‐infected group, but did not differ from the subgroup of cART‐naïve HIV‐infected adults. A higher aHR of incident CVD was associated with comorbid hypertension (aHR = 2.18), diabetes (aHR = 1.38), obesity (aHR = 1.30), tobacco use (aHR = 1.47), and hepatitis C coinfection (aHR = 1.32), and older age (aHR = 1.26), but with a lower risk among females (aHR = 0.86). A higher risk of incident CVD events was also apparent in HIV‐infected individuals with exposure to both protease inhibitors (adjusted risk ratio [aRR] = 1.99) and non‐nucleoside reverse transcriptase inhibitors (aRR = 2.19) compared to those with no exposure. Sustained viral load suppression was associated with a lower risk of incident CVD events (aRR = 0.74).ConclusionsAfter adjusting for traditional risk factors and sociodemographic differences, there is higher risk of incident cardiovascular events among HIV‐infected individuals exposed to combined antiretroviral medications compared to the general population.
Synthesis and Crystal Structures of Gold Nanowires with Gemini Surfactants as Directing Agents
Authors: Xu Feng , Hou Hao , Gao Zhinong 
Published: September 2014

AbstractThe preparation of crystalline gold nanowires (NWs) by using gemini surfactants as directing agents through a three‐step seed‐mediated method is reported. Unlike the nanorods with relatively low aspect ratios (typically below 20) obtained by using cetyltrimethylammonium bromide as a directing agent, the NWs obtained in this investigation can reach up to 4.4 μm, and the largest aspect ratio is calculated to be 210. For this, each of seven different gemini surfactants are utilized as directing agents, and the length and/or aspect ratio of the NWs can be tuned by varying the hydrocarbon chain lengths of the gemini surfactants. Both single and twinned crystalline structures are elucidated by selected‐area electron diffraction and high‐resolution transmission electron microscopy studies. The use of gemini surfactants not only advances the synthesis of gold nanostructures, but improves the understanding of the growth mechanism for seed‐mediated growth.
Integrating environmental, molecular, and morphological data to unravel an ice‐age radiation of arctic‐alpine Campanula in western North America
Authors: DeChaine Eric G. , Wendling Barry M. , Forester Brenna R. 
Published: September 2014

AbstractMany arctic‐alpine plant genera have undergone speciation during the Quaternary. The bases for these radiations have been ascribed to geographic isolation, abiotic and biotic differences between populations, and/or hybridization and polyploidization. The Cordilleran Campanula L. (Campanulaceae Juss.), a monophyletic clade of mostly endemic arctic‐alpine taxa from western North America, experienced a recent and rapid radiation. We set out to unravel the factors that likely influenced speciation in this group. To do so, we integrated environmental, genetic, and morphological datasets, tested biogeographic hypotheses, and analyzed the potential consequences of the various factors on the evolutionary history of the clade. We created paleodistribution models to identify potential Pleistocene refugia for the clade and estimated niche space for individual taxa using geographic and climatic data. Using 11 nuclear loci, we reconstructed a species tree and tested biogeographic hypotheses derived from the paleodistribution models. Finally, we tested 28 morphological characters, including floral, vegetative, and seed characteristics, for their capacity to differentiate taxa. Our results show that the combined effect of Quaternary climatic variation, isolation among differing environments in the mountains in western North America, and biotic factors influencing floral morphology contributed to speciation in this group during the mid‐Pleistocene. Furthermore, our biogeographic analyses uncovered asynchronous consequences of interglacial and glacial periods for the timing of refugial isolation within the southern and northwestern mountains, respectively. These findings have broad implications for understanding the processes promoting speciation in arctic‐alpine plants and the rise of numerous endemic taxa across the region.
Desert salt flats as oases for the spider Saltonia incerta Banks (Araneae: Dictynidae)
Authors: Crews Sarah C. , Gillespie Rosemary G. 
Published: September 2014

AbstractThe deserts of southwestern North America have undergone dramatic changes over their recent geological history including large changes in size and connectivity during the Pleistocene glaciopluvial cycles. This study examines the population history of the rare spider Saltonia incerta, once thought to be extinct, to determine the role of past climatological events in shaping the structure of the species. This species is restricted to salt crusts of intermittent or dry lakes, streams or rivers in the desert southwest, a region that was much wetter during glacial periods. We examine the distribution and genetic variability of populations to test whether there is recent dispersal throughout the range of the species. Analyses of mitochondrial and nuclear DNA indicate significant population structure, with one major clade comprising New Mexico localities and one comprising California‐northern Baja California localities. Finer‐scale structure is evident within the California clade, although not all of the subclades are reciprocally monophyletic. However, isolation with migration analysis suggests that migration is very low to non‐existent. These results extend the known distribution of Saltonia, provide genetic evidence of strong isolation among localities within drainage basins and between drainage basins and provide a mechanistic understanding of population connectivity after the aridification of the American southwest. The implication is that although the species' distribution has been fragmented, populations have persisted throughout this area, suggesting that desert salt flats may have served as refugia for at least some terrestrial species.
Assembly of a 1H‐Pyrrol‐2(5H)‐one Core through a Cascade Ugi Reaction/5‐endo‐dig Carbocyclization/Retro‐Claisen Fragmentation Process
Authors: Peshkov Anatoly A. , Peshkov Vsevolod A. , Li Zhenghua , Pereshivko Olga P. , Van der Eycken Erik V. 
Published: September 2014

AbstractA cascade transformation involving the Ugi reaction followed by 5‐endo‐dig carbocyclization and retro‐Claisen fragmentation providing access to a 1H‐pyrrol‐2(5H)‐one core is described. The operating protocol is very similar to the typical Ugi reaction settings, while the overall outcome results from the application of a 3‐substituted propiolic acid and a phenylglyoxal as acid and aldehyde components, respectively. The utility of process is demonstrated through the synthesis of a small library of 5‐oxo‐2,5‐dihydro‐1H‐pyrrole‐2‐carboxamides.
Voltammetric Determination of Pb(II) and Cd(II) Ions in Well Water Using a Sputtered Bismuth Screen‐Printed Electrode
Authors: Sosa Velia , Serrano Núria , Ariño Cristina , Díaz‐Cruz José Manuel , Esteban Miquel 
Published: September 2014

AbstractA method using commercially available sputtered bismuth screen‐printed electrodes (BispSPE), as substitute to mercury electrodes, for the determination of trace Pb(II) and Cd(II) ions in drinking well water samples collected in a contaminated area in The Republic of El Salvador by means of differential pulse anodic stripping voltammetry (DPASV) has been proposed. The comparable detection and quantification limits obtained for both BispSPE and hanging mercury drop electrode (HMDE), together with the similar results with a high reproducibility obtained in these water samples analyses recommend the applicability of BispSPE for the determination of low level of metal concentrations in natural samples.
Redox Mechanism and Evaluation of Kinetic and Thermodynamic Parameters of 1,3‐Dioxolo[4,5‐g]pyrido[2,3‐b]quinoxaline Using Electrochemical Techniques
Authors: Shah Aamir Hassan , Shah Afzal , Rana Usman Ali , Khan Salah Ud‐Din , Hussain Hidayat , Khan Sher Bahadar , Qureshi Rumana , Badshah Amin 
Published: September 2014

AbstractThe electrochemical behavior of a biologically important heterocyclic compound, 1,3‐dioxolo[4,5‐g]pyrido[2,3‐b]quinoxaline was investigated by cyclic, square wave and differential pulse voltammetry in solutions of different pH. Kinetic and thermodynamic parameters like standard rate constant, diffusion coefficient, apparent energy of activation, standard Gibbs free energy and enthalpy and entropy changes were evaluated. Limits of detection and quantification were determined by square wave voltammetry. The redox mechanism of the compound was proposed on the basis of experimental results. Computational chemistry was used as a tool for the verification of experimental outcomes and assessment of different theoretical parameters
Development of Graphene/CdSe Quantum Dots‐Co Phthalocyanine Nanocomposite for Oxygen Reduction Reaction
Authors: Nyoni Stephen , Nyokong Tebello 
Published: September 2014

AbstractNanocomposites containing CdSe quantum dots, tetra(4‐(4,6‐diaminopyrimidin‐2‐ylthio) phthalocyaninatocobalt(II)) (CoPyPc) and reduced graphene nanosheets (rGNS) were devoloped and used for the modification of a glassy carbon electrode. Characterization of the nanocomposites was done by transmission electron microscopy (TEM) and X‐ray diffraction (XRD) analyses. Cyclic voltammetry (CV) was used for electrochemical characterization of the prepared nanocomposite for oxygen reduction reaction. The oxygen reduction activity for rGNS/CdSe‐CoPyPc nanocomposite was found to be superior over the individual nanomaterials in this study. The activity of the nanocomposite towards oxygen reduction was also tested for tolerance to methanol crossover effect using chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) studies.
Radiation‐induced epithelial‐myoepithelial carcinoma in a patient previously treated with mantle‐field radiation therapy for Hodgkin lymphoma
Authors: Mann Justin M. , Kellman Robert M. , Hahn Seung S. , de la Roza Gustavo L. , Gajra Ajeet 
Published: September 2014

AbstractBackgroundRadiation‐induced salivary gland tumors are well described in the literature, with mucoepidermoid cancer being the most common histologic entity. Epithelial‐myoepithelial carcinoma is a rare tumor accounting for <1% of all tumors in the salivary glands.Methods and ResultsWe describe the first case of radiation‐induced epithelial‐myoepithelial carcinoma in the English‐language medical literature. A 48‐year‐old man presented with right‐sided mandibular pain and trismus, 25 years after mantle‐field radiation therapy (RT) for Hodgkin lymphoma. He underwent excision of a right submandibular mass, which revealed a diagnosis of epithelial‐myoepithelial carcinoma. Although typically a low‐grade tumor, the histology revealed extensive necrosis and high mitotic activity. The patient required multiple resections and adjuvant therapy after multiple recurrences over a 4‐year period.ConclusionReports of epithelial‐myoepithelial carcinoma are relatively rare and this case highlights the importance of long‐term follow‐up and increased awareness of the risks of salivary gland tumors in this population. © 2014 Wiley Periodicals, Inc. Head Neck 37: E96–E98, 2015
Dental implants in irradiated versus nonirradiated patients: A meta‐analysis
Authors: Chrcanovic Bruno Ramos , Albrektsson Tomas , Wennerberg Ann 
Published: September 2014

AbstractThe purpose of the present meta‐analysis was to test the null hypothesis of no difference in dental implant failure rates, postoperative infection, and marginal bone loss for patients being rehabilitated by dental implants and being previously irradiated in the head and neck region versus nonirradiated patients against the alternative hypothesis of a difference. The study suggests that irradiation negatively affects the survival of implants, as well as the difference in implant location (maxilla vs mandible), but there is no statistically significant difference in survival when implants are inserted before or after 12 months after radiotherapy. The study failed to support the effectiveness of hyperbaric oxygen therapy in irradiated patients. It was observed that there was a tendency of lower survival rates of implants inserted in the patients submitted to higher irradiation doses. The results should be interpreted with caution because of the presence of uncontrolled confounding factors in the included studies. © 2015 Wiley Periodicals, Inc. Head Neck 38: 448–481, 2016