bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silver Nanoparticles Supported on CeO2‐SBA‐15 by Microwave Irradiation Possess Metal–Support Interactions and Enhanced Catalytic Activity
Authors: Qian Xufang , Kuwahara Yasutaka , Mori Kohsuke , Yamashita Hiromi 
Published: October 2014

AbstractMetal–support interactions (MSIs) and particle size play important roles in catalytic reactions. For the first time, silver nanoparticles supported on CeO2‐SBA‐15 supports are reported that possess tunable particle size and MSIs, as prepared by microwave (MW) irradiation, owing to strong charge polarization of CeO2 clusters (i.e., MW absorption). Characterizations, including TEM, X‐ray photoelectron spectroscopy, and extended X‐ray absorption fine structure, were carried out to disclose the influence of CeO2 contents on the Ag particle size, MSI effect between Ag nanoparticles and CeO2‐SBA‐15 supports, and the strong MW absorption of CeO2 clusters that contribute to the MSIs during Ag deposition. The Ag particle sizes were controllably tuned from 1.9 to 3.9 nm by changing the loading amounts of CeO2 from 0.5 to 2.0 wt %. The Ag nanoparticle size was predominantly responsible for the high turnover frequency (TOF) of 0.41 min−1 in ammonia borane dehydrogenation, whereas both particle size and MSIs contributed to the high TOF of 555 min−1 in 4‐nitrophenol reduction for Ag/0.5CeO2‐SBA‐15, which were twice as large as those of Ag/SBA‐15 without CeO2 and Ag/CeO2‐SBA‐15 prepared by conventional oil‐bath heating.
A Strategy for the Preparation of Thioantimonates Based on the Concept of Weak Acids and Corresponding Strong Bases
Authors: Anderer Carolin , Delwa de Alarcón Natalie , Näther Christian , Bensch Wolfgang 
Published: October 2014

AbstractBy following a new synthetic approach, which is based on the in situ formation of a basic medium by the reaction between the strong base Sb(V)S43− and the weak acid H2O, it was possible to prepare three layered thioantimonate(III) compounds of composition [TM(2,2′‐bipyridine)3][Sb6S10] (TM=Ni, Fe) and [Ni(4,4′‐dimethyl‐2,2′‐bipyridine)3][Sb6S10] under hydrothermal conditions featuring two different thioantimonate(III) network topologies. The antimony source, Na3SbS4 ⋅ 9 H2O, undergoes several decomposition reactions and produces the SbIIIS3 species, which condenses to generate the layered anion. The application of transition‐metal complexes avoids crystallization of dense phases. The reactions are very fast compared to conventional hydrothermal/solvothermal syntheses and are much less sensitive to changes of the reaction parameters.
Fused Perylene–Phthalocyanine Macrocycles: A New Family of NIR‐Dyes with Pronounced Basicity
Authors: Schönamsgruber Jörg , Maid Harald , Bauer Walter , Hirsch Andreas 
Published: October 2014

AbstractThe synthesis and characterization of a new type of chromophore, namely PePc consisting of a central phthalocyanine core and four fused perylene–bisimide (PBI) units is described for the first time. The entire architecture represents a highly extended conjugated heterocyclic π‐system with C4h symmetry. In order to guarantee pronounced solubility in organic solvents the corresponding PBI units were bay‐functionalized with tert‐butylphenoxy substituents. Next to the metal‐free macrocycle, PePcH2, also metallated macrocycles PePcM (M=Zn, Ni, Pb, Ru, Fe) were synthesized. The extensive fusion of the corresponding aromatic building blocks to the very large extended π‐system leads to a very narrow HOMO–LUMO gap and as a consequence to transparency in the visible but light absorption in the NIR region. Significantly, the azomethine N‐atoms N1N4 of PePcM and PePcH2 are highly basic. The corresponding tetraprotonated systems can only be deprotonated with very strong non‐nucleophilic bases such as phosphazene bases. In the protonated forms PePcMH44+ and PePcMH64+ the absorption maximum is shifted back to the visible region due to the loss of conjugation. The experimental findings were corroborated with quantum mechanical calculations.
Environment‐Sensitive Probes Containing a 2,6‐Diethynylpyridine Motif for Fluorescence Turn‐On Detection and Induction of Nanoarchitectures of Human Telomeric Quadruplex
Authors: Das Rabindra Nath , Debnath Manish , Gaurav Abhiket , Dash Jyotirmayee 
Published: October 2014

AbstractBis(phenylethynyl)pyridylcarboxamides with amide side chains at the para position of the NH2 group possess strong solvatochromic properties compared with the meta analogues. Fluorescence binding titrations show that these probes exhibit remarkable fluorescence turn‐on responses upon interacting with the human telomeric G‐quadruplex (h‐TELO). Förster resonance energy transfer melting analysis shows the high selectivity of these probes for h‐TELO over duplex DNA. Isothermal titration calorimetry, as well as UV/Vis and fluorescence spectroscopy studies, show that the meta analogue has a twofold binding affinity for h‐TELO over the para analogue. The noncovalent interaction of these small‐molecule probes with h‐TELO has been used to regulate the assembly of novel supramolecular nanoarchitectures.
Synthesis of a Rigid C3v‐Symmetric Tris‐salicylaldehyde as a Precursor for a Highly Porous Molecular Cube
Authors: Elbert Sven M. , Rominger Frank , Mastalerz Michael 
Published: October 2014

AbstractThe development of a synthetic approach to a C3v‐symmetric tris‐salicylaldehyde based on triptycene is presented. The tris‐salicylaldehyde is a versatile precursor for porous molecular materials, as demonstrated in the [4+4] condensation reaction with a triptycene triamine to form a molecular shape‐persistent porous cube. The amorphous material of the molecular porous cube shows a very high surface area of 1014 m2 g−1 (BET model) and a high uptake of CO2 (18.2 wt % at 273 K and 1 bar). Furthermore, during the multistep synthesis of the tris‐salicylaldehyde precursor, a relatively rare (twofold) addition of the aryne to the anthracene in the 1,4‐ and 1,4,5,8‐positions have been found during a Diels–Alder reaction, as proven by X‐ray structure analysis.
Metal–Organic Framework‐Derived Copper Nanoparticle@Carbon Nanocomposites as Peroxidase Mimics for Colorimetric Sensing of Ascorbic Acid
Authors: Tan Hongliang , Ma Chanjiao , Gao Li , Li Qian , Song Yonghai , Xu Fugang , Wang Tao , Wang Li 
Published: October 2014

AbstractMetal–organic frameworks (MOFs) have emerged as very fascinating functional materials due to their diversity nature. A nanocomposite consisting of copper nanoparticles dispersed within a carbon matrix (Cu NPs@C) is prepared through a one‐pot thermolysis of copper‐based metal–organic framework precursors. Cu NPs@C can catalyze the oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) to form a colored product in the presence of H2O2. As a peroxidase mimic, Cu NPs@C not only has the advantages of low cost, high stability, and easy preparation, but also follows Michaelis–Menten behaviors and shows strong affinity to H2O2. As the Cu NPs’ surfaces are free from stabilizing agent, Cu NPs@C exhibited a higher affinity to H2O2 than horseradish peroxidase. On the basis of the inhibitory effect of ascorbic acid (AA) on oxidation of TMB, this system serves as a colorimetric method for the detection of AA, suggesting that the present work would expand the potential applications of MOF‐derived nanocomposites in biomedical fields.
Versatile Reagent Ph3As(OTf)2: One‐Pot Synthesis of [P7(AsPh3)3][OTf]3 from PCl3
Authors: Donath Maximilian , Bodensteiner Michael , Weigand Jan J. 
Published: October 2014

AbstractCompound Ph3As(OTf)2 as a pentacoordinated AsV Lewis acid readily forms dicationic Lewis acid/base adducts upon addition of various Lewis bases. It also represents a stronger chloride‐abstracting agent than Me3SiOTf and facilitates the reductive coupling of PCl3 in the presence of AsPh3 to the unprecedented cation [P7(AsPh3)3]3+ as triflate salt. This crystallographically characterized nortricyclane‐type cation represents a P7R3‐derivative with the most electron‐withdrawing substituents, resulting in a pronounced effect on the structural parameters of the P7 core.
Oxygen‐Initiated Stereoselective Thermal Isomerisation of a Cyclobutane Derivative in the Solid State
Authors: Chanthapally Anjana , Yang Hui , Quah Hong Sheng , Webster Richard D. , Schreyer Martin K. , Wong Ming Wah , Vittal Jagadese J. 
Published: October 2014

AbstractSolid‐state [2+2] photochemical cycloaddition reactions have been extensively studied after the classical work of Schmidt in the 1960s. Of these, trans‐1,2‐bis(4′‐pyridyl)ethylene (bpe) is one of the well‐studied alkenes to synthesize tetrakis(4‐pyridyl)cyclobutane (tpcb). However, almost all the solid‐state [2+2] cycloaddition reactions of bpe yielded, almost exclusively, one of the four possible isomers, namely, the rctt‐tpcb (r=regio c=cis and t=trans). Here we describe a stereoselective synthesis of the tetrahedrally disposed rtct‐tpcb by the solid‐state thermal isomerization of the rctt‐isomer in atmospheric air. We propose that this isomerization occurs through a topochemical unimolecular mechanism by a radical chain pathway, initiated by molecular oxygen. This is supported by the nature of products formed in air and nitrogen, detection of a radical in ESR spectral studies, ESI‐MS crossover experiments, VT PXRD studies along with QM, MD and docking calculations. The formation of a unique isomer by thermal isomerization may be a general phenomenon to quantitatively synthesize other useful stereoisomers from the existing isomers of cyclobutane derivatives.
Hospitalization Costs for Acute Myocardial Infarction Patients Treated With Percutaneous Coronary Intervention in the United States Are Substantially Higher Than Medicare Payments
Authors: Afana Majed , Brinjikji Waleed , Cloft Harry , Salka Samer 
Published: October 2014

ABSTRACTBackgroundAcute coronary syndromes account for half of all deaths secondary to cardiovascular disease and represent a significant economic burden in the United States. Therefore, assessing hospitalization costs relative to Medicare reimbursement for these patients is important in understanding the impact of these patients on hospitals. We hypothesized that hospitalization costs for acute myocardial infarction patients treated with percutaneous coronary intervention (PCI) were higher than their associated Medicare payments.MethodsUsing the Nationwide Inpatient Sample, we evaluated hospitalization costs for patients treated with PCI from 2001 through 2009 by multiplying hospital charges by the group average cost‐to‐charge ratio for each patient's hospitalization. Primary end points examined were total hospital costs and trends over time, which were correlated with clinical outcomes and insurance payments. Costs were inflation adjusted with 2009 as the reference year.ResultsMedian hospitalization costs of PCI increased from $15 889 (interquartile range [IQR] = $12 057–$21 204) in 2001 to $19 349 (IQR = $14 660–$26 282) in 2009. From 2004 to 2009, inflation‐adjusted costs for PCI decreased at a rate of 0.3% per year. In 2009, a total of 265,531 patients received PCI for acute myocardial infarction. Of these, 143 654 were <65 years old, and 121 876 were ≥65 years old. Average 2009 Medicare payments ranged from $9303 to $17 500 depending on the Medicare Severity‐Diagnosis Related Groups (MS‐DRG) billed, leaving hospitals at a loss of anywhere from $4493 to $7940 per patient when comparing costs and reimbursements across all included MS‐DRG codes.ConclusionsHospitalization costs for patients treated with PCI have been stabilizing over the last few years; however, there still remains a significant disparity between Medicare reimbursements and hospitalization costs, which has potential implications on patient outcomes, quality of care, and hospital sustainability.
Design of gem‐Difluoro‐bis‐Tetrahydrofuran as P2 Ligand for HIV‐1 Protease Inhibitors to Improve Brain Penetration: Synthesis, X‐ray Studies, and Biological Evaluation
Authors: Ghosh Arun K. , Yashchuk Sofiya , Mizuno Akira , Chakraborty Nilanjana , Agniswamy Johnson , Wang Yuan‐Fang , Aoki Manabu , Gomez Pedro Miguel Salcedo , Amano Masayuki , Weber Irene T. , Mitsuya Hiroaki 
Published: October 2014

AbstractThe structure‐based design, synthesis, biological evaluation, and X‐ray structural studies of fluorine‐containing HIV‐1 protease inhibitors are described. The synthesis of both enantiomers of the gem‐difluoro‐bis‐THF ligands was carried out in a stereoselective manner using a Reformatskii–Claisen reaction as the key step. Optically active ligands were converted into protease inhibitors. Two of these inhibitors, (3R,3aS,6aS)‐4,4‐difluorohexahydrofuro[2,3‐b]furan‐3‐yl(2S,3R)‐3‐hydroxy‐4‐((N‐isobutyl‐4‐methoxyphenyl)sulfonamido)‐1‐phenylbutan‐2‐yl) carbamate (3) and (3R,3aS,6aS)‐4,4‐difluorohexahydrofuro[2,3‐b]furan‐3‐yl(2S,3R)‐3‐hydroxy‐4‐((N‐isobutyl‐4‐aminophenyl)sulfonamido)phenylbutan‐2‐yl) carbamate (4), exhibited HIV‐1 protease inhibitory Ki values in the picomolar range. Both 3 and 4 showed very potent antiviral activity, with respective EC50 values of 0.8 and 3.1 nM against the laboratory strain HIV‐1LAI. The two inhibitors exhibited better lipophilicity profiles than darunavir, and also showed much improved blood–brain barrier permeability in an in vitro model. A high‐resolution X‐ray structure of inhibitor 4 in complex with HIV‐1 protease was determined, revealing that the fluorinated ligand makes extensive interactions with the S2 subsite of HIV‐1 protease, including hydrogen bonding interactions with the protease backbone atoms. Moreover, both fluorine atoms on the bis‐THF ligand formed strong interactions with the flap Gly 48 carbonyl oxygen atom.
Results of phase 2 randomized study of low‐dose decitabine with or without valproic acid in patients with myelodysplastic syndrome and acute myelogenous leukemia
Authors: Issa Jean‐Pierre , Garcia‐Manero Guillermo , Huang Xuelin , Cortes Jorge , Ravandi Farhad , Jabbour Elias , Borthakur Gautam , Brandt Mark , Pierce Sherry , Kantarjian Hagop M. 
Published: October 2014

BACKGROUNDHypomethylating agents have demonstrated activity in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Preclinical and single‐arm trials have suggested that adding histone deacetylase (HDAC) inhibitors may synergize the epigenetic modulation of hypomethylating agents and improve treatment results.METHODSThe objective of this study was to evaluate the possible benefit of adding valproic acid, an HDAC inhibitor, to decitabine in the treatment of MDS and AML.RESULTSPatients with higher risk MDS or with AML aged ≥60 years were eligible. Patients were randomized in a Bayesian response‐adaptive design to receive intravenous decitabine 20 mg/m2 daily for 5 days or decitabine plus oral valproic acid 50 mg/kg daily for 7 days. Courses were repeated every 4 to 6 weeks. A maximum of 150 patients were to be treated. In total, 149 patients were treated on study, including 87 patients with MDS and 62 patients with AML. The median patient age was 69 years (range, 20‐89 years; 42% of patients were aged ≥70 years). Overall, 34% of patients achieved complete remission, and 55% had an objective response. The median survival was 11.9 months, and the estimated 2‐year survival rate was 27%. Outcome was not different with the addition of valproic acid to decitabine versus decitabine alone in relation to the rates of complete remission, overall response, or survival. Subset analyses did not demonstrate a benefit within the MDS or AML categories. Toxicities—particularly neurotoxicities—were higher with the combination arm.CONCLUSIONSAdding valproic acid to decitabine was not associated with improved outcome in the treatment of patients with MDS or elderly patients with AML. Future therapies may consider combining hypomethylating agents with better HDAC inhibitors and using different schedules. Cancer 2015;121:556–561. © 2014 American Cancer Society.
Colloidal Synthesis and Photocatalytic Performance of Size‐Controllable Solid or Hollow CuInSe2 Nanocrystals
Authors: Sheng Pengtao , Li Weili , Wang Xin , Tong Xi , Cai Qingyun 
Published: October 2014

AbstractMorphology evolution dependence on reaction time has been investigated to find a way to overcome polydispersity of the chalcopyrite CuInSe2 nanocrystals (NCs). A building–crumbling process is presented to understand the formation of small NCs. By carefully controlling magnetic stirring, ligand content, and duration, the polydispersity is fundamentally improved; thus solid and hollow spherical NCs and quantum dots can be easily obtained with tunable sizes. It is proposed that the NCs undergo Ostwald ripening induced morphology evolution from solid to hollow NCs. The photoelectric properties and photocatalytic activity have been investigated with TiO2 nanotube array based photoelectrodes. A maximum saturation photocurrent of 12.6 mA cm−2 has been achieved, and a structure‐dependent photocatalytic property has also been confirmed by using methyl orange as a model pollutant.
General Approach for High‐Power Li‐Ion Batteries: Multiscale Lithographic Patterning of Electrodes
Authors: Choi Sinho , Kim Tae‐Hee , Lee Jung‐In , Kim Jieun , Song Hyun‐Kon , Park Soojin 
Published: October 2014

AbstractWe demonstrate multiscale patterned electrodes that provide surface‐area enhancement and strong adhesion between electrode materials and current collector. The combination of multiscale structured current collector and active materials (anodes and cathodes) enables us to make high‐performance Li‐ion batteries (LIBs). When LiFePO4 (LFP) cathode and Li4Ti5O12 (LTO) anode materials are combined with patterned current collectors, their electrochemical performances are significantly improved, including a high rate capability (LiFePO4: 100 mAh g−1, Li4Ti5O12: 60 mAh g−1 at 100C rate) and highly stable cycling (LiFePO4: capacity retention of 99.8 % after 50 cycles at 10C rate). Moreover, we successfully fabricate full cell system consisting of patterned LFP cathode and patterned LTO anode, exhibiting high‐power battery performances [capacity of approximately 70 mAh g−1 during 1000 cycles at 10C rate (corresponding to charging/discharging time of 6 min)]. We extend this idea to Si anode that exhibits a large volume change during lithiation/delithiation process. The patterned Si electrodes show significantly enhanced electrochemical performances, including a high specific capacity (825 mAh g−1) at high rate of 5C and a stable cycling retention (88 % after 100 cycle at a 0.1C rate). This simple strategy can be extended to other cathode and anode materials for practical LIB applications.
A Catalytic Reactor for the Organocatalyzed Enantioselective Continuous Flow Alkylation of Aldehydes
Authors: Porta Riccardo , Benaglia Maurizio , Puglisi Alessandra , Mandoli Alessandro , Gualandi Andrea , Cozzi Pier Giorgio 
Published: October 2014

AbstractThe use of immobilized metal‐free catalysts offers the unique possibility to develop sustainable processes in flow mode. The challenging intermolecular organocatalyzed enantioselective alkylation of aldehydes was performed for the first time under continuous flow conditions. By using a packed‐bed reactor filled with readily available supported enantiopure imidazolidinone, different aldehydes were treated with three distinct cationic electrophiles. In the organocatalyzed α‐alkylation of aldehydes with 1,3‐benzodithiolylium tetrafluoroborate, excellent enantioselectivities, in some cases even better than those obtained in the flask process (up to 95 % ee at 25 °C), and high productivity (more than 3800 h−1) were obtained, which thus shows that a catalytic reactor may continuously produce enantiomerically enriched compounds. Treatment of the alkylated products with Raney‐nickel furnished enantiomerically enriched α‐methyl derivatives, key intermediates for active pharmaceutical ingredients and natural products.
On elastic traffic via contention resolution diversity slotted aloha satellite access
Authors: Celandroni Nedo , Davoli Franco , Ferro Erina , Gotta Alberto 
Published: October 2014

SummaryThis paper presents a performance study relative to the coupling of the Transmission Control Protocol (TCP) with the Contention Resolution Diversity slotted aloha (CRDSA) protocol, in the case of greedy TCP connections (also called elephants) on Digital Video Broadcasting‐Return Channel via a geostationary satellite. CRDSA, which takes advantage of interference cancellation algorithms for collision/contention resolution, has already exhibited interesting performance when the power levels of all received bursts are perfectly balanced. In this paper, we extend the study to a more realistic case, where a certain spreading of the bursts' power levels is taken into account. The consequent capture effect even facilitates the collision resolution mechanism and yields an improvement in the overall TCP performance with respect to the balanced case. Furthermore, in certain conditions, the adoption of packet level forward error correction allows achieving even higher peaks of throughput than the expected ones. Copyright © 2014 John Wiley & Sons, Ltd.
Mitigation of the moving radio interferences in the OFDM‐based power line communication channels in China
Authors: Ming‐Yue Zhai 
Published: October 2014

SummaryUnder some special environments in China, there exist moving radio radiations with high transmission powers that can degrade the performance of the power line communications systems significantly. Such radiations overlap with the OFDM‐based signals in time and frequency domains, and hence, it is very difficult to mitigate directly if not possible. The paper introduced the fractional Fourier transform trying to deal with such moving radio interferences. When using the fractional Fourier transform to separate signals and noises/interferences, the fractional order plays a key role, but there is no method to obtain its optimal value in the published papers. In the paper, like for the time‐frequency representations, we defined the second moments of the fractional Fourier transform of the signal. The fractional order, corresponding the maximum of the second moments, is the one used to separate the OFDM signals and the moving radio interferences, which is modelled as the Doppler signals in our scheme. The proposed method can mitigate the moving radio interferences significantly by applying the proposed method to the simulated OFDM signals and the measurements data. The results also show that the system's BERs can be improved from 10−2 to 10−5 for lower signal‐noise‐rate (SNR), and from 10−4 to 10−9 for high SNRs. Copyright © 2014 John Wiley & Sons, Ltd.