bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bioinspired Directional Surfaces for Adhesion, Wetting, and Transport
Authors: Hancock Matthew J. , Sekeroglu Koray , Demirel Melik C. 
Published: March 2012

AbstractIn Nature, directional surfaces on insect cuticle, animal fur, bird feathers, and plant leaves are composed of dual micro‐nanoscale features that tune roughness and surface energy. Here, experimental and theoretical approaches for the design, synthesis, and characterization of new bioinspired surfaces demonstrating unidirectional surface properties are summarized. The experimental approaches focus on bottom‐up and top‐down synthesis methods of unidirectional micro‐ and nanoscale films to explore and characterize their anomalous features. The theoretical component focuses on computational tools to predict the physicochemical properties of unidirectional surfaces.
Protamine Functionalized Single‐Walled Carbon Nanotubes for Stem Cell Labeling and In Vivo Raman/Magnetic Resonance/Photoacoustic Triple‐Modal Imaging
Authors: Wang Chao , Ma Xinxing , Ye Shuoqi , Cheng Liang , Yang Kai , Guo Liang , Li Changhui , Li Yonggang , Liu Zhuang 
Published: March 2012

AbstractStem cells have shown great potential in regenerative medicine and attracted tremendous interests in recent years. Sensitive and reliable methods for stem cell labeling and in vivo tracking are thus urgently needed. Here, a novel approach to label human mesenchymal stem cells (hMSCs) with single‐walled carbon nanotubes (SWNTs) for in vivo tracking by triple‐modal imaging is presented. It is shown that polyethylene glycol (PEG) functionalized SWNTs conjugated with protamine (SWNT‐PEG‐PRO) exhibit extremely efficient cell entry into hMSCs, without affecting their proliferation and differentiation. The strong inherent resonance Raman scattering of SWNTs is used for in vitro and in vivo Raman imaging of SWNT‐PEG‐PRO‐labeled hMSCs, enabling ultrasensitive in vivo detection of as few as 500 stem cells administrated into mice. On the other hand, the metallic catalyst nanoparticles attached on nanotubes can be utilized as the T2‐contrast agent in magnetic resonance (MR) imaging of SWNT‐labeled hMSCs. Moreover, in vivo photoacoustic imaging of hMSCs in mice is also demonstrated. The work reveals that SWNTs with appropriate surface functionalization have the potential to serve as multifunctional nanoprobes for stem cell labeling and multi‐modal in vivo tracking.
Light‐Driven Chiral Molecular Switches or Motors in Liquid Crystals
Authors: Wang Yan , Li Quan 
Published: March 2012

AbstractThe ability to tune molecular self‐organization with an external stimulus is a main driving force in the bottom‐up nanofabrication of molecular devices. Light‐driven chiral molecular switches or motors in liquid crystals that are capable of self‐organizing into optically tunable helical superstructures undoubtedly represent a striking example, owing to their unique property of selective light reflection and which may lead to applications in the future. In this review, we focus on different classes of light‐driven chiral molecular switches or motors in liquid crystal media for the induction and manipulation of photoresponsive cholesteric liquid crystal systems and their consequent applications. Moreover, the change of helical twisting powers of chiral dopants and their capability of helix inversion in the induced cholesteric phases are highlighted and discussed in the light of their molecular geometric changes.
A Cobalt‐Catalyzed Domino Route to the ABC Tricyclic Core of Strigolactones and Analogues
Authors: Le Floch Camille , Laymand Kévin , Le Gall Erwan , Léonel Eric 
Published: March 2012

AbstractThe cobalt‐catalyzed, one‐step synthesis of fused tricyclic cyclopenta[b]furan‐2‐ones from β‐halo‐α,β‐unsaturated aldehydes and dimethyl itaconate is described. The final compounds contain the ABC tricyclic core of strigolactones or analogues, vegetables hormones involved in various, crucial biological processes.
Platinum on Carbon‐Catalyzed Hydrodefluorination of Fluoroarenes using Isopropyl Alcohol‐Water‐Sodium Carbonate Combination
Authors: Sawama Yoshinari , Yabe Yuki , Shigetsura Masahiro , Yamada Tsuyoshi , Nagata Saori , Fujiwara Yuta , Maegawa Tomohiro , Monguchi Yasunari , Sajiki Hironao 
Published: March 2012

AbstractWe have developed a platinum on carbon‐isopropyl alcohol‐catalyzed and widely applicable defluorination method for fluoroarenes, and the addition of water and sodium carbonate efficiently accelerated the reaction. The defluorination readily occurred under the reaction conditions in comparison with the dehalogenation of other aromatic halides (fluorine>chlorine>bromine≫iodine).
Hydrothermal and Solvothermal Process Towards Development of LiMPO4 (M = Fe, Mn) Nanomaterials for Lithium‐Ion Batteries
Authors: Devaraju Murukanahally Kempaiah , Honma Itaru 
Published: March 2012

AbstractPositive electrodes such as LiFePO4 and LiMnPO4 nanomaterials with olivine structures are considered as most efficient cathode materials for application in lithium ion batteries. Recently, several methods have been proposed for the preparation of lithium metal phosphates as cathodes for lithium ion batteries and their electrochemical performances have been investigated. Over the last 20 years, several synthetic methods have been proposed for lithium metal phosphate nanomaterials. In this review, hydrothermal and solvothermal syntheses of LiFePO4 and LiMnPO4 nanomaterials at low and high temperatures are discussed, including microwave‐hydrothermal and microwave‐solvothermal methods. The effect of particle size and particle morphology on the electrochemical properties of LiFePO4 and LiMnPO4 cathode materials are also discussed. In addition, the recently emerged supercritical solvothermal and supercritical hydrothermal syntheses of LiFePO4 and LiMnPO4 nanomaterials and their electrochemical property also been addressed.
Efficient Phthalimide Copolymer‐Based Bulk Heterojunction Solar Cells: How the Processing Additive Influences Nanoscale Morphology and Photovoltaic Properties
Authors: Xin Hao , Guo Xugang , Ren Guoqiang , Watson Mark D. , Jenekhe Samson A. 
Published: March 2012

AbstractThe power conversion efficiency of poly(N‐(2‐ethylhexyl)‐3,6‐bis(4‐dodecyloxythiophen‐2‐yl)phthalimide) (PhBTEH)/fullerene bulk heterojunction solar cells improves from 0.43 to 4.1% by using a processing additive. The underlying mechanism for the almost 10‐fold enhancement in solar cell performance is found to be inhibition of fullerene intercalation into the polymer side chains and regulation of the relative crystallization/aggregation rates of the polymer and fullerene. An optimal interconnected two‐phase morphology with 15–20 nm domains is obtained when a processing additive is used compared with 100–300 nm domains without the additive. The results demonstrate that a processing additive provides an effective means of controlling both the fullerene intercalation in polymer/fullerene blends and the domain sizes of their phase‐separated nanoscale morphology.
Synthesis and Biological Evaluation of 1‐Phenyl‐1,2,3,4‐dihydroisoquinoline Compounds as Tubulin Polymerization Inhibitors
Authors: Zheng Can‐Hui , Chen Jun , Liu Jia , Zhou Xiao‐Tian , Liu Na , Shi Duo , Huang Jing‐Jing , Lv Jia‐Guo , Zhu Ju , Zhou You‐Jun 
Published: March 2012

AbstractA series of 1‐phenyl‐3,4‐dihydroisoquinoline derivatives and several 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline, 1‐phenyl‐isoquinoline analogues were synthesized, and their cytotoxicity and tubulin polymerization inhibitory activity were evaluated. The 1‐phenyl‐3,4‐dihydroisoquinoline compounds were found to be potential tubulin polymerization inhibitors. Compound 5n, bearing a 3′OH and 4′OCH3 substituted 1‐phenyl B‐ring, was shown to confer optimal bioactivity. The single‐crystal structure of 5n was further determined by X‐ray diffraction, and the binding mode of 5n to tubulin was obtained by molecular docking, which can explain the structure–activity relationships. The studies presented here provide a new structural type for the development of novel antitumor agents.
Fleet size determination for a truckload distribution center
Authors: Huang Shan‐Huen , Yang Ta‐Hui , Tang Ching‐Hui 
Published: March 2012

SUMMARYThis work presents an analysis of the fleet size determination problem for a truckload distribution center in which each customer requests multi‐truckload services. A transformation is made to define this problem as a cutting stock problem which can be resolved by finding the proper set of patterns beneficial for an NP‐hard (non‐deterministic polynomial‐time hard) problem. The genetic algorithm (GA) is combined with cutting stock techniques to solve the problem. Experiments are carried out testing two types of problems, with and without time‐window constraints. To verify the solution quality obtained with the proposed approach, the problem is also solved using only GA. It is shown that the proposed approach can significantly improve the GA solution by 14.68%. Copyright © 2012 John Wiley & Sons, Ltd.
FRET microscopy in the living cell: Different approaches, strengths and weaknesses
Authors: Padilla‐Parra Sergi , Tramier Marc 
Published: March 2012

AbstractNew imaging methodologies in quantitative fluorescence microscopy, such as Förster resonance energy transfer (FRET), have been developed in the last few years and are beginning to be extensively applied to biological problems. FRET is employed for the detection and quantification of protein interactions, and of biochemical activities. Herein, we review the different methods to measure FRET in microscopy, and more importantly, their strengths and weaknesses. In our opinion, fluorescence lifetime imaging microscopy (FLIM) is advantageous for detecting inter‐molecular interactions quantitatively, the intensity ratio approach representing a valid and straightforward option for detecting intra‐molecular FRET. Promising approaches in single molecule techniques and data analysis for quantitative and fast spatio‐temporal protein‐protein interaction studies open new avenues for FRET in biological research.
Scanning image correlation spectroscopy
Authors: Digman Michelle A. , Gratton Enrico 
Published: March 2012

AbstractMolecular interactions are at the origin of life. How molecules get at different locations in the cell and how they locate their partners is a major and partially unresolved question in biology that is paramount to signaling. Spatio‐temporal correlations of fluctuating fluorescently tagged molecules reveal how they move, interact, and bind in the different cellular compartments. Methods based on fluctuations represent a remarkable technical advancement in biological imaging. Here we discuss image analysis methods based on spatial and temporal correlation of fluctuations, raster image correlation spectroscopy, number and brightness, and spatial cross‐correlations that give us information about how individual molecules move in cells and interact with partners at the single molecule level. These methods can be implemented with a standard laser scanning microscope and produce a cellular level spatio‐temporal map of molecular interactions.
UV Radiation Induces Genome‐Mediated, Site‐Specific Cleavage in Viral Proteins
Authors: Wigginton Krista Rule , Menin Laure , Sigstam Therese , Gannon Greg , Cascella Michele , Hamidane Hisham Ben , Tsybin Yury O. , Waridel Patrice , Kohn Tamar 
Published: March 2012

AbstractMuch research has been dedicated to understanding the molecular basis of UV damage to biomolecules, yet many questions remain regarding the specific pathways involved. Here we describe a genome‐mediated mechanism that causes site‐specific virus protein cleavage upon UV irradiation. Bacteriophage MS2 was disinfected with 254 nm UV, and protein damage was characterized with ESI‐ and MALDI‐based FT‐ICR, Orbitrap, and TOF mass spectroscopy. Top‐down mass spectrometry of the products identified the backbone cleavage site as Cys46–Ser47 in the virus capsid protein, a location of viral genome–protein interaction. The presence of viral RNA was essential to inducing backbone cleavage. The similar bacteriophage GA did not exhibit site‐specific protein cleavage. Based on the major protein fragments identified by accurate mass analysis, a cleavage mechanism is proposed by radical formation. The mechanism involves initial oxidation of the Cys46 side chain followed by hydrogen atom abstraction from Ser47 Cα. Computational protein QM/MM studies confirmed the initial steps of the radical mechanism. Collectively, this study describes a rare incidence of genome‐induced protein cleavage without the addition of sensitizers.
A Flavoprotein Monooxygenase that Catalyses a Baeyer–Villiger Reaction and Thioether Oxidation Using NADH as the Nicotinamide Cofactor
Authors: Jensen Chantel N. , Cartwright Jared , Ward Jonathan , Hart Sam , Turkenburg Johan P. , Ali Sohail T. , Allen Michael J. , Grogan Gideon 
Published: March 2012

AbstractA gene from the marine bacterium Stenotrophomonas maltophilia encodes a 38.6 kDa FAD‐containing flavoprotein (Uniprot B2FLR2) named S. maltophilia flavin‐containing monooxygenase (SMFMO), which catalyses the oxidation of thioethers and also the regioselective Baeyer–Villiger oxidation of the model substrate bicyclo[3.2.0]hept‐2‐en‐6‐one. The enzyme was unusual in its ability to employ either NADH or NADPH as nicotinamide cofactor. The KM and kcat values for NADH were 23.7±9.1 μM and 0.029 s−1 and 27.3±5.3 μM and 0.022 s−1 for NADPH. However, kcat/KM value for the ketone substrate in the presence of 100 μM cofactor was 17 times greater for NADH than for NADPH. SMFMO catalysed the quantitative conversion of 5 mM ketone in the presence of substoichiometric concentrations of NADH with the formate dehydrogenase cofactor recycling system, to give the 2‐oxa and 3‐oxa lactone products of Baeyer–Villiger reaction in a ratio of 5:1, albeit with poor enantioselectivity. The conversion with NADPH was 15 %. SMFMO also catalysed the NADH‐dependent transformation of prochiral aromatic thioethers, giving in the best case, 80 % ee for the transformation of p‐chlorophenyl methyl sulfide to its R enantiomer. The structure of SMFMO reveals that the relaxation in cofactor specificity appears to be accomplished by the substitution of an arginine residue, responsible for recognition of the 2′‐phosphate on the NADPH ribose in related NADPH‐dependent FMOs, with a glutamine residue in SMFMO. SMFMO is thus representative of a separate class of single‐component, flavoprotein monooxygenases that catalyse NADH‐dependent oxidations from which possible sequences and strategies for developing NADH‐dependent biocatalysts for asymmetric oxygenation reactions might be identified.
Meta‐analysis of complications in aortic valve replacement: Comparison of Medtronic‐Corevalve, Edwards‐Sapien and surgical aortic valve replacement in 8,536 patients
Authors: Jilaihawi Hasan , Chakravarty Tarun , Weiss Robert E. , Fontana Gregory P. , Forrester James , Makkar Raj R. 
Published: March 2012

AbstractBackground: We sought to establish the complication rates following transcatheter aortic valve replacement (TAVR) in the context of high risk and octogenarian surgical aortic valve replacement (SAVR) in the contemporary literature, and to critically analyze population characteristics and outcomes. Methods: TAVR studies were selected from nonoverlapping series and SAVR studies for comparison if they met similar entry criteria. Bayesian meta‐analytic methods were employed. Results: For the 5024 TAVR and 3512 SAVR patients included in the study, TAVR subjects had greater baseline renal impairment (P < 0.001), a higher incidence of prior myocardial infarction (P = 0.032) and respiratory disease (P = 0.005) and a higher logistic EuroSCORE (P = 0.039). There were no significant differences observed in complications studied in SAVR and TAVR: 30 day mortality (9% vs 8.5%, P = 0.31), 1 year mortality (18.4% vs 22.8%, P = 0.65), 30 day stroke (2.4% vs 2.6%, P = 0.72), new permanent pacemaker (5.9% vs 12.1%, P = 0.055) and dialysis inception (2.4% vs 4.1%, P = 0.70). We also compared demographics and outcomes between the two types of transcatheter valves. Apart from some variation in functional status, there were no significant differences at baseline with different TAVR designs. The only difference in complications was the need for pacemaker insertion, higher with the Medtronic‐Corevalve than with the Edwards‐Sapien design (24.5% vs 5.9% P < 0.0001). Conclusions: Complications for elderly and high risk aortic stenosis patients being treated by TAVR appear comparable to those selected for SAVR in the real‐world. © 2012 Wiley Periodicals, Inc.
Carbon–Carbon Bond Formation by Ligand‐free Cross‐Coupling Reaction Using Palladium Catalyst Supported on Synthetic Adsorbent
Authors: Monguchi Yasunari , Sakai Keita , Endo Koichi , Fujita Yuki , Niimura Masaru , Yoshimura Masatoshi , Mizusaki Tomoteru , Sawama Yoshinari , Sajiki Hironao 
Published: March 2012

AbstractA palladium catalyst supported on a commercial synthetic adsorbent, DIAION HP20, could be employed for the crosscoupling reactions of aryl halides with organoboronic acids (Suzuki–Miyaura reaction), alkenes (Mizoroki–Heck reaction), and alkynes (Sonogashira reaction) in a ligand‐free manner. 10 % Pd/HP20 was highly active as the catalyst at approximately the same level as 10 % palladium on carbon (10 % Pd/C) for many of the reactions, and was especially effective for the Suzuki–Miyaura reaction using bromoaniline derivatives without the N‐protection and Sonogashira reaction of the heteroaryl iodides. As a stable supply and certain quality of HP20 are available as an industrial product, 10 % Pd/HP20 would be in practical use for a variety of cross‐coupling reactions and hydrogenation as the substitute for 10 % Pd/C, which is dependent on charcoal as a natural product.
Kinetics of Isothermal Ethanol Adsorption onto a Carbon Molecular Sieve under Conventional and Microwave Heating
Authors: Adnadjević B. K. , Jovanović J. D. 
Published: March 2012

AbstractThe isothermal kinetics of ethanol adsorption from aqueous solution onto a zeolite type carbon molecular sieve (CMS‐3A) under conventional heating (CH) and microwave heating (MWH) was investigated. The adsorption kinetics is described by the model of a phase‐boundary controlled reaction for both heating modes. The activation energy (Ea) for the adsorption process under MWH is lower than under CH while the preexponential factor (lnA) is higher. Ethanol adsorption is a kinetically complex process whose complexity changes with the mode of heating. The established decrease in Ea and increase in lnA under MWH compared to CH is explained with the increase in the ground vibrational level of the – OH twisting vibrations in the ethanol molecule and with the decrease in its anharmonicity factor which is caused by the selective resonant transfer of energy from CMS‐3A to the OH oscillators.
Geometric and Electronic Structures of Phenoxyl Radicals Hydrogen Bonded to Neutral and Cationic Partners
Authors: Orio Maylis , Jarjayes Olivier , Baptiste Benoit , Philouze Christian , Duboc Carole , Mathias Jenny‐Lee , Benisvy Laurent , Thomas Fabrice 
Published: March 2012

AbstractTwo di‐tert‐butylphenols incorporating an N‐methylbenzimidazole moiety in the ortho or para position have been synthesised (MeOH and pMeOH, respectively). Their X‐ray structures evidence a hydrogen bond between the phenolic proton and the iminic nitrogen atom, whose nature is intra‐ and intermolecular, respectively. The present studies demonstrate that MeOH is readily oxidised by an intramolecular PET mechanism to form the hydrogen‐bonded phenoxyl‐N‐methylbenzimidazolium system (MeOH).+, whereas oxidation of pMeOH occurs by intermolecular PET, affording the neutral phenoxyl benzimidazole (pMeO). system. The deprotonations of MeOH and pMeOH yield the corresponding phenolate species (MeO)− and (pMeO)−, respectively, whilst that of the previously reported HOH (analogous to MeOH but lacking the N‐methyl group) produces an unprecedented hydrogen‐bonded phenol benzimidazolate species, as evidenced by its X‐ray structure. The latter is believed to be in equilibrium in solution with its tautomeric phenolate form, as suggested by NMR, electrochemistry and DFT studies. The one‐electron oxidations of the anions occur by a simple ET process affording phenoxyl radical species, whose electronic structure has been studied by HF‐EPR spectroscopy and DFT calculations. In particular, analysis of the g1 tensor shows the order 2.0079>2.0072>2.0069>2.0067 for (MeO)., (HO)., (MeOH).+ and (HOH).+, respectively. (MeO). exhibits the largest g1 tensor (2.0079), consistent with the absence of intramolecular hydrogen bond. The g1 tensor of (HO). is intermediate between those of (MeOH).+ and (MeO). (g1=2.0072), indicating that the phenoxyl oxygen is hydrogen‐bonded with a neutral benzimidazole partner.
Near‐IR Excitation Transfer and Electron Transfer in a BF2‐Chelated Dipyrromethane–Azadipyrromethane Dyad and Triad
Authors: El‐Khouly Mohamed E. , Amin Anu N. , Zandler Melvin E. , Fukuzumi Shunichi , D'Souza Francis 
Published: March 2012

AbstractA molecular dyad and triad, comprised of a known photosensitizer, BF2‐chelated dipyrromethane (BDP), covalently linked to its structural analog and near‐IR emitting sensitizer, BF2‐chelated tetraarylazadipyrromethane (ADP), have been newly synthesized and the photoinduced energy and electron transfer were examined by femtosecond and nanosecond laser flash photolysis. The structural integrity of the newly synthesized compounds has been established by spectroscopic, electrochemical, and computational methods. The DFT calculations revealed a molecular‐clip‐type structure for the triad, in which the BDP and ADP entities are separated by about 14 Å with a dihedral angle between the fluorophores of around 70°. Differential pulse voltammetry studies have revealed the redox states, allowing estimation of the energies of the charge‐separated states. Such calculations revealed a charge separation from the singlet excited BDP (1BDP*) to ADP (BDP.+‐ADP.−) to be energetically favorable in nonpolar toluene and in polar benzonitrile. In addition, the excitation transfer from the singlet BDP to ADP is also envisioned due to good spectral overlap of the BDP emission and ADP absorption spectra. Femtosecond laser flash photolysis studies provided concrete evidence for the occurrence of energy transfer from 1BDP* to ADP (in benzonitrile and toluene) and electron transfer from BDP to 1ADP* (in benzonitrile, but not in toluene). The kinetic study of energy transfer was measured by monitoring the rise of the ADP emission and revealed fast energy transfer (ca. 1011 s−1) in these molecular systems. The kinetics of electron transfer via 1ADP*, measured by monitoring the decay of the singlet ADP at λ=820 nm, revealed a relatively fast charge‐separation process from BDP to 1ADP*. These findings suggest the potential of the examined ADP–BDP molecules to be efficient photosynthetic antenna and reaction center models.
Total Synthesis of Exiguamines A and B Inspired by Catecholamine Chemistry
Authors: Sofiyev Vladimir , Lumb Jean‐Philip , Volgraf Matthew , Trauner Dirk 
Published: March 2012

AbstractThe evolution of a total synthesis of the exiguamines, two structurally unusual natural products that are highly active inhibitors of indolamine‐2,3‐dioxygenase (IDO), is described. The ultimately successful strategy involves advanced cross‐coupling methodology and features a potentially biosynthetic tautomerization/electrocyclization cascade reaction that forms two heterocycles and installs a quaternary ammonium ion in a single synthetic operation.