bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topology‐Reset Execution: Repeatable Postcyclization Recyclization of Cyclic Polymers
Authors: Honda Satoshi , Oka Minami , Takagi Hideaki , Toyota Taro 
Published: October 2018

AbstractRepeatable topological transformation of polymers for the modulation of material functions is a challenge. We have developed a method for repeatedly resetting a cyclic macromolecular architecture to a linear architecture by photostimulation, namely, topology‐reset execution (T‐rex) based on the photochemistry of hexaarylbiimidazoles (HABIs). We synthesized cyclic poly(dimethylsiloxane)s (PDMSs) of various ring sizes with HABIs linked in the chains. UV irradiation of the cyclic PDMSs produced telechelic linear PDMSs with triphenylimidazolyl radical (TPIR) end groups. After termination of UV irradiation, end‐to‐end recyclization occurred by the recoupling of TPIRs. The cyclic PDMSs also responded to ultrasound, which decreased their molecular weight (MW) by site‐specific cleavage of in‐chain HABI moieties, and we are able to reset the MWs by subsequent phototriggered T‐rex. Furthermore, T‐rex enabled solvent‐free switching of the rheological properties of the materials while retaining the liquid character of PDMS.
Probing Hydrogen Bonding Interactions to Iron‐Oxido/Hydroxido Units by 57Fe Nuclear Resonance Vibrational Spectroscopy
Authors: Weitz Andrew C. , Hill Ethan A. , Oswald Victoria F. , Bominaar Emile L. , Borovik Andrew S. , Hendrich Michael P. , Guo Yisong 
Published: October 2018

AbstractHydrogen bonds (H‐bonds) have been shown to modulate the chemical reactivities of iron centers in iron‐containing dioxygen‐activating enzymes and model complexes. However, few examples are available that investigate how systematic changes in intramolecular H‐bonds within the secondary coordination sphere influence specific properties of iron intermediates, such as iron‐oxido/hydroxido species. Here, we used 57Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the Fe‐O/OH vibrations in a series of FeIII‐hydroxido and FeIV/III‐oxido complexes with varying H‐bonding networks but having similar trigonal bipyramidal primary coordination spheres. The data show that even subtle changes in the H‐bonds to the Fe‐O/OH units result in significant changes in their vibrational frequencies, thus demonstrating the utility of NRVS in studying the effect of the secondary coordination sphere to the reactivities of iron complexes.
Chiral Guanidine/Copper Catalyzed Asymmetric Azide‐Alkyne Cycloaddition/[2+2] Cascade Reaction
Authors: Guo Songsong , Dong Pei , Chen Yushuang , Feng Xiaoming , Liu Xiaohua 
Published: October 2018

AbstractWe report the development of a chiral guanidine‐based copper(I) catalyst for the asymmetric azide‐alkyne cycloaddition/[2+2] cascade reaction. Optically active spiroazetidinimine oxindoles were constructed by trapping the ketenimine species under mild reaction conditions. High level of enantioinduction and excellent isolated yields were achieved in the three‐component reaction of various isatin‐derived ketimines, sulfonyl azides, and terminal alkynes. Control experiments and X‐ray crystallography were used to probe into the interaction of chiral guanidinium salt with copper salt.
Bond Energies of Adsorbed Intermediates to Metal Surfaces: Correlation with Hydrogen–Ligand and Hydrogen–Surface Bond Energies and Electronegativities
Authors: Carey Spencer J. , Zhao Wei , Campbell Charles T. 
Published: October 2018

AbstractUnderstanding what controls the strength of bonding of adsorbed intermediates to transition‐metal surfaces is of central importance in many technologies, especially catalysis and electrocatalysis. Our recently measured bond enthalpies of −OH, −OCH3, −O(O)CH and −CH3 to Pt(111) and Ni(111) surfaces are fit well (standard deviation of 7.2 kJ mol−1) by a predictive equation involving only known parameters (gas‐phase ligand–hydrogen bond enthalpies, bond enthalpies of adsorbed H atoms to that surface, electronegativities of the elements, and group electronegativities of the ligands). This equation is based upon Pauling's equation, with improvements introduced by Matcha, derived here following manipulations of Matcha's equation similar to (but going beyond) those introduced by Schock and Marks to explain ligand–metal bond enthalpy trends in organometallic complexes.
Creating Biomorphic Barbed and Branched Mesostructures in Solution through Block Copolymer Crystallization
Authors: Jia Lin , Guerin Gerald , Lu Yijie , Yu Qing , Manners Ian , Winnik Mitchell A. 
Published: October 2018

AbstractBranched and barbed structures are common in nature but rare in nanoscale or mesoscale objects formed by bottom‐up self‐assembly. Key characteristics of the morphology of natural objects, such as various types of insects and conifer branches, is that despite their similarities no two individual objects are exactly the same. Here we report the self‐assembly conditions for a series of poly(ferrocenyldimethylsilane)‐block‐polyisoprene (PFS‐b‐PI) diblock copolymers that generate structures with biomorphic shapes. All of these polymers yield long uniform fiber‐like micelles with a crystalline PFS core in decane. Injection of a concentrated THF solution of these polymers into THF/decane mixtures, however, leads to barbed and branched mesostructures, with shapes that depend upon the final THF content of the mixed solvent. Interestingly, evaporation of the THF from suspensions of the colloidal biomorphic structures led to elongated fiber‐like structures.
Integrating DNA Photonic Wires into Light‐Harvesting Supramolecular Polymers
Authors: Kownacki Mariusz , Langenegger Simon M. , Liu Shi‐Xia , Häner Robert 
Published: October 2018

AbstractAn approach combining DNA nanoscaffolds with supramolecular polymers for the efficient and directional propagation of light‐harvesting cascades has been developed. A series of photonic wires with different arrangements of fluorophores in DNA‐organized nanostructures were linked to light‐harvesting supramolecular phenanthrene polymers (SPs) in a self‐assembled fashion. Among them, a light‐harvesting complex (LHC) composed of SPs and a photonic wire of phenanthrene, Cy3, Cy5, and Cy5.5 chromophores reveals a remarkable energy transfer efficiency of 59 %. Stepwise transfer of the excitation energy collected by the light‐harvesting SPs via the intermediate Cy3 and Cy5 chromophores to the final Cy5.5 acceptor proceeds through a Förster resonance energy transfer mechanism. In addition, the light‐harvesting properties are documented by antenna effects ranging from 1.4 up to 23 for different LHCs.
Isomerism in Titanium‐Oxo Clusters: Molecular Anatase Model with Atomic Structure and Improved Photocatalytic Activity
Authors: Fan Xi , Wang Junhui , Wu Kaifeng , Zhang Lei , Zhang Jian 
Published: October 2018

AbstractPhase isomerism is a common and important phenomenon in inorganic materials, but the molecular isomerism of their nanocluster models is still rare. In this work, we report the first pair of isomeric titanium‐oxo clusters. Through combining pentagonal {Ti(Ti5)} building units in corner‐sharing or edge‐sharing forms, the two obtained Ti20‐oxo clusters take vertical and horizontal core configurations, respectively, which are both functionalized by the same organic ligands. More interestingly, the vertical type Ti20‐oxo core contains an identical {Ti8O14} moiety as anatase, making it the first molecular model of anatase TiO2. As a result, the vertical type cluster exhibits better photocatalytic H2 evolution activity, higher photocurrent response and faster charge transfer to external acceptors than its horizontal isomer. Thus, this work provides a cluster isomer method to understand the structure–property relationship of import titanium oxide materials.
Nickel‐Catalyzed Mizoroki–Heck‐Type Reactions of Unactivated Alkyl Bromides
Authors: Kwiatkowski Megan R. , Alexanian Erik J. 
Published: October 2018

AbstractThe development of a general, nickel‐catalyzed alkyl‐Mizoroki–Heck reaction of unactivated alkyl bromides is described. The mild reaction proceeds efficiently using a wide range of primary and secondary alkyl bromides, and examples of intermolecular cross‐couplings are provided. Reaction alkene regioselectivity is significantly enhanced over prior carbocyclizations using palladium catalysis. Mechanistic investigations are consistent with a direct carbocyclization in contrast to the auto‐tandem atom‐transfer cyclization and halide elimination previously observed with palladium catalysis.
Palladium‐Catalyzed Decarbonylative Difluoromethylation of Acid Chlorides at Room Temperature
Authors: Pan Fei , Boursalian Gregory B. , Ritter Tobias 
Published: October 2018

AbstractMethods for the direct synthesis of difluoromethylated arenes are sparse, despite the importance of the difluoromethyl group in medical, agro‐, and materials chemistry. A palladium‐catalyzed decarbonylative cross‐coupling reaction of acid chlorides with a difluoromethyl zinc reagent is achieved to access difluoromethylated compounds. The transformation proceeds at room temperature and shows broad functional group tolerance, thus providing a general and efficient method for decarbonylative difluoromethylation of a wide range of aromatic carboxylic acids.
31P NMR Method for Phospholipid Analysis in Krill Oil: Proficiency Testing—A Step toward Becoming an Official Method
Authors: Zailer Elina , Monakhova Yulia B. , Diehl Bernd W. K. 
Published: October 2018

AbstractA high‐resolution 31P NMR method for determining the concentration of phospholipid (PL) species in krill oil was proficiency tested using an international interlaboratory study. Fourteen laboratories from five countries tested five different krill oil samples providing 17 datasets. Krill oil samples were prepared by the organizer using liquid–liquid extraction and sent to the participants who ran the nuclear magnetic resonance (NMR) analysis and evaluated the spectra. The relative standard deviation (RSD) among all the results provided by the participants varied between 2.1% and 3.3% for the phosphatidylcholine (PtdCho) content and between 2.8% and 12.3% for the sum of other PL. Afterward, an automated procedure was applied to all collected NMR data, which significantly improved the RSD values and provided reliable quantitative results for specific PL (PtdCho, 1‐lysophosphatidylcholine [LPC], 2‐LPS, PtdEtn, acylphosphatidylethanolamine [APE], and lysophosphatidylethanolamine [LPE]). The RSD varied between 1.6% and 2.7% for PtdCho and between 1.6% and 2.9% for the total phosphorus. Higher but acceptable values were obtained for 1‐LPC (5.1% to 8.9%), PtdEtn (7.0% to 10.5%), and LPE (5.7% to 16.5%) due to their small concentrations. The influence of different magnetic field strengths (400–600 MHz), probes, and slight differences in acquisition parameters was assessed as nonsignificant. PtdCho hydrolysis during 14 weeks before measurements was the major factor that affects the result distribution. This method was submitted to the AOCS to become an official AOCS method for krill oil analysis.
The Influence of Body Size and Bone Mass on Cortical Bone Histomorphometry in Human Ribs
Authors: Beresheim Amy C. , Pfeiffer Susan K. , Alblas Amanda 
Published: October 2018

ABSTRACTThis study examines the influence of human adult body size and bone mass on cortical bone histomorphometry, and explores microstructural variation in mid‐thoracic ribs. The sample consists of 213 individuals (nfemale = 82, nmale = 131, mean age‐at‐death = 47.96 ± 15.71 years) from the Kirsten Skeletal Collection, Stellenbosch University, South Africa. Maximum femur length and femur maximum head diameter are used as proxies for height and weight; total cross‐sectional area, endosteal area, and cortical area are used to derive measures of bone mass. Histomorphometric variables include osteon population density (OPD) and osteon area (On.Ar). Partial correlations, controlling for age, test for significant relationships among variables. A hierarchical regression model is used to determine unique variable contributions to On.Ar and OPD. Body size measurements do not correlate with either bone mass or histomorphometric variables, suggesting that size‐standardization may not be necessary in studies of rib bone microstructure. Age is the most significant factor affecting OPD, while OPD is the best predictor of On.Ar. These findings suggest that age‐related secondary osteon crowding affects osteon geometry. Understanding the biological mechanisms that direct bone remodeling and determine microstructural variation is essential for interpreting histological data. Anat Rec, 301:1788–1796, 2018. © 2018 Wiley Periodicals, Inc.
Fluorescent, Recombinant‐Protein‐Conjugated, Near‐Infrared‐Emitting Quantum Dots for in Vitro and in Vivo Dual‐Color Molecular Imaging
Authors: Tsuboi Setsuko , Jin Takashi 
Published: October 2018

AbstractNear‐infrared (NIR)‐emitting fluorescent probes are widely used for molecular imaging at the whole‐body level. However, NIR‐emitting fluorescent probes emitting over λ=700 nm are not suitable for molecular imaging at the cellular level, because most of the conventional fluorescence microscopes have very low optical sensitivity in the NIR region. Thus, to achieve fluorescence imaging at the cellular and whole‐body levels by using single probes, visible and NIR‐emitting dual‐color fluorescent probes are desirable. For dual‐color fluorescence molecular imaging, we synthesized fluorescent, recombinant‐protein‐conjugated, NIR‐emitting quantum dots (QDs), in which the recombinant protein consists of enhanced green fluorescent protein (EGFP) and the immunoglobulin binding domain (B1) of protein G. This dual‐color fluorescent QD probe binds the Fc region of immunoglobulin G (IgG) through its B1 domain at the QD surface and acts as a molecular‐imaging probe at both the cellular and whole‐body levels. In this paper, we present the synthesis of fluorescent, recombinant protein (HisEGFP‐GB1)‐conjugated, NIR‐emitting QDs and their application to the dual‐color molecular imaging of breast cancer cells in vitro and in vivo.
Effect of glucose and palmitate environment on proliferation and migration of PC3‐prostate cancer cells
Authors: Rezende Lívia Prometti , Galheigo Maria Raquel Unterkircher , Landim Breno Costa , Cruz Amanda Rodrigues , Botelho Françoise Vasconcelos , Zanon Renata Graciele , Góes Rejane Maira , Ribeiro Daniele Lisboa 
Published: October 2018

AbstractRecent studies have been trying to find out how diet and metabolic changes such as dyslipidaemia, hyperglycaemia, and hyperinsulinaemia can stimulate cancer progression. This investigation aimed to evaluate the effect of high concentrations of fatty acids and/or glucose in tumour prostate cells, focusing on the proliferation/migration profile and oxidative stress. PC3 cells were treated with high concentration of saturated fatty acid (palmitate, 100 µM), glucose (220 mg/dL), or both for 24 or 48 h. Results demonstrated that PC3 cells showed a significant increase in proliferation after 48 h of treatment with glucose and palmitate+glucose. Cell proliferation was associated with reduced levels of AMPK phosphorylation in glucose group at 24 and 48 h of treatment, while palmitate group presented this result only after 48 h of treatment. Also, there was a significant increase in cell migration between time 0 and 48 h after all treatments, except in the control. Catalase activity was increased by palmitate in the beginning of treatment, while glucose presented a later effect. Also, nitrite production was increased by glucose only after 48 h, and the total antioxidant activity was enhanced by palmitate in the initial hours. Thus, we conclude that the high concentration of the saturated fatty acid palmitate and glucose in vitro influences PC3 cells and stimulates cellular activities related to carcinogenesis such as cell proliferation, migration, and oxidative stress in different ways. Palmitate presents a rapid and initial effect, while a glucose environment stimulates cells later on, maintaining high levels of cell proliferation.
SAPIEN valve for percutaneous transcatheter pulmonary valve replacement without “pre‐stenting”: A multi‐institutional experience
Authors: Morgan Gareth J. , Sadeghi Soraya , Salem Moris M. , Wilson Neil , Kay Joseph , Rothman Abraham , Galindo Alvaro , Martin Mary Hunt , Gray Robert , Ross Michael , Aboulhosn Jamil A. , Levi Daniel Steven 
Published: October 2018

AbstractObjectivesTo describe a multicenter experience of percutaneous transcatheter pulmonary valve replacement (TPVR) using the Edwards SAPIEN S3 valve without the use of a prior stent (“pre‐stenting”).BackgroundThe SAPIEN S3 and XT valves have durable cobalt–chromium stent frames which may allow for TPVR in large diameter dysfunctional right ventricular outflow tracts (RVOTs) without pre‐stenting the landing zone.MethodsA retrospective review was performed of all patients with Congenital Heart Disease and dysfunctional RVOT who underwent TPVR using the SAPIEN valve without the use of a pre‐stent. Imaging data, procedural elements, and clinical follow‐up data were collected to evaluate short and intermediate‐term results.ResultsFifty‐seven patients underwent percutaneous placement of the SAPIEN valve in the pulmonary position without the use of pre‐stenting. The anatomical substrate varied: native RVOTs (n = 41), conduits (n = 10), and bioprosthetic valves (n = 6). There were no cases in which the valve could not be implanted and no cases of valve embolization or misplacement. On follow‐up (range 1 month to 2.2 years, median 5.3 months), no patients had significant obstruction or regurgitation around the valve. There were no frame fractures. There were no procedural deaths. Major complications included severe aortic compression (n = 1) requiring surgical explantation and tricuspid valve injury requiring surgical intervention (n = 2).ConclusionsThis limited multi‐institutional experience demonstrates that the SAPIEN valve can be used for TPVR without the use of a pre‐stent without medium‐term risk of frame fracture, paravalvar leak, or embolization. Longer term follow‐up is required to fully assess this method.
Green Conversion of Microalgae into High‐Performance Sponge‐Like Nitrogen‐Enriched Carbon
Authors: Liu Yingying , Dai Gongxin , Zhu Lingjun , Wang Shurong 
Published: October 2018

AbstractThe selective conversion of biomass into high‐value carbon materials has recently been attracting increasing attraction. In this study, a microalga with a high nitrogen content, namely Spirulina platensis, was used as both the carbon and nitrogen precursors in the synthesis of sponge‐like nitrogen‐enriched carbon materials through a one‐step activation method with NaHCO3 as a green activator. The sponge‐like nitrogen‐enriched carbon materials obtained at different activation temperatures were systematically characterized by using SEM, N2 adsorption‐desorption, XRD, Raman, and XPS techniques. A series of tests were performed to investigate the electrochemical characteristics of the obtained carbon materials to determine their potential use as supercapacitors. The results show that sponge‐like nitrogen‐enriched carbon activated at 700 °C, which has a large BET surface area of 865 m2/g and a high nitrogen content of 7.5 wt%, gave the largest specific capacitance of 234.0 F/g at a current density of 1 A/g in a 6 M KOH electrolyte.
Rare‐Earth Metal Diimide Complexes via Alkylaluminate Templating, Including a Ceric Derivative
Authors: Thim Renita , Schädle Dorothea , Maichle‐Mössmer Cäcilia , Anwander Reiner 
Published: October 2018

AbstractProtonolysis of lanthanide tris(tetramethylaluminate)s with two equivalents of 2,6‐diisopropylaniline affords LaIII and CeIII diimide compounds Ln[(μ‐NC6H3iPr2‐2,6)2AlMe2](thf)4 featuring a bidentate AlMe2‐linked diimido ligand. As revealed for the corresponding Ce(GaMe4)3‐reaction, formation of the diimide complexes proceeds via tetrametallic complexes of the type [Ce{(μ‐NC6H3iPr2‐2,6)(HNC6H3iPr2‐2,6)(MMe3)}]2 (Me=Al, Ga). Oxidation of the cerium(III) complex with hexachloroethane leads to a neutral CeIV diimide species. Partial protonolysis with phenylacetylene and hydrogenolysis via H3SiPh give conclusive insights into the reactive coordination sites of such diimide complexes.
Selective Optimization of Pranlukast to Farnesoid X Receptor Modulators
Authors: Schierle Simone , Schmidt Jurema , Kaiser Astrid , Merk Daniel 
Published: October 2018

AbstractSelective optimization of side activities (SOSA) offers an alternative entry to early drug discovery and may provide rapid access to bioactive new chemical entities with desirable properties. SOSA aims to reverse a drug's side activities through structural modification and to design out the drug's original main action. We identified a moderate side activity for the cysteinyl leukotriene receptor 1 (CysLT1R) antagonist pranlukast on the farnesoid X receptor (FXR). Systematic structural modification of the drug allowed remarkable optimization of its partial FXR agonism to sub‐nanonmolar potency. The resulting FXR modulators lack any activity on CysLT1R and are characterized by high selectivity, high metabolic stability, and low toxicity. With their favorable in vitro profile, these SOSA‐derived FXR modulators constitute a new FXR ligand chemotype that appears suitable for further preclinical evaluation.
Identification and Biological Evaluation of Novel Type II B‐RafV600E Inhibitors
Authors: Wang Peng‐Fei , Wang Ze‐Feng , Qiu Han‐Yue , Huang Yue , Hu Hui‐Min , Wang Zhong‐Chang , Zhu Hai‐Liang 
Published: October 2018

AbstractThe mitogen‐activated protein kinase (MAPK) pathway plays a vital role in signal transduction networks. Severe diseases may be triggered if it is disturbed by mutated components, especially the kinase B‐RafV600E. New inhibitors of the kinase are needed as cases of relapse and resistance with the known drugs have been widely reported in the clinic. In the present work, a new class of B‐RafV600E inhibitors was identified by fragment linking. In vitro and in vivo assays were used to demonstrate the pharmacological properties of the compounds. 3‐{3‐[4‐Chloro‐3‐(trifluoromethyl)phenyl]ureido}‐N‐[1‐(4‐methoxyphenyl)‐1H‐pyrazol‐4‐yl]benzamide was the most potent agent with IC50 values of 0.035±0.004 μm (B‐RafV600E kinase) and 0.39±0.04 μm (A375 cells). Furthermore, no obvious toxicity was observed. Collectively, the results favored justified the design rationale and hinted that this new chemotype might be worth studying further to develop novel B‐Raf inhibitor candidates.