bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Affinity Recognition of a Selected Amino Acid Epitope within a Protein by Cucurbit[8]uril Complexation
Authors: Sonzini Silvia , Marcozzi Alessio , Gubeli Raphael J. , van der Walle Christopher F. , Ravn Peter , Herrmann Andreas , Scherman Oren A. 
Published: October 2016

AbstractSupramolecular interactions between the host cucurbit[8]uril (CB[8]) and amino acids have been widely interrogated, but recognition of specific motifs within a protein domain have never been reported. A phage display approach was herein used to select motifs with the highest binding affinity for the heteroternary complex with methyl viologen and CB[8] (MV⋅CB[8]) within a vast pool of cyclic peptide sequences. From the selected motifs, an epitope consisting of three amino acid was extrapolated and incorporated into a solvent‐exposed loop of a protein domain; the protein exhibited micromolar binding affinity for the MV⋅CB[8] complex, matching that of the cyclic peptide. By achieving selective CB[8]‐mediated conjugation of a small molecule to a recombinant protein scaffold we pave the way to biomedical applications of this simple ternary system.
Nucleophil‐dirigierte Stereokontrolle über Glykosylierungsreaktionen durch geminal‐difluorierte Nucleophile
Authors: Schumann Benjamin , Parameswarappa Sharavathi G. , Lisboa Marilda P. , Kottari Naresh , Guidetti Fabio , Pereira Claney L. , Seeberger Peter H. 
Published: October 2016

AbstractDie Glykosylierung ist der wichtigste Schritt bei der Synthese komplexer Oligosaccharide, oft allerdings mit geringer Kontrolle der Stereoselektivität verbunden. Die Einführung cis‐glykosidischer Bindungen ist besonders aufwändig und kann bislang fast nur durch Wahl von Glykosylierungsreagens oder Reaktionsbedingungen kontrolliert werden. Hier wird gezeigt, dass die Wahl des Nucleophils eine bedeutende Rolle bei der Stereokontrolle von Glykosylierungen spielt. Durch Einführung zweier Fluorsubstituenten wird die O‐Nucleophilie eines aliphatischen Aminoalkohols herabgesetzt, was zu einer Umkehr der Stereoselektivität von Glykosylierungen zugunsten der gewünschten cis‐Glykoside in einer Reihe von Substraten führt. Dieses Prinzip wurde beim Entwurf eines cis‐selektiven Linkers für die automatisierte Glykansynthese angewendet. Fluorierung eines Aminoalkohol‐Linkers beeinträchtigt nicht die Immobilisierung und Erkennung von Glykanen durch Lektine in Glykan‐Mikroarray‐Experimenten. Fluorierte Linker eignen sich zur Herstellung α‐terminierender Glykanstrukturen für den Aufbau von Glykokonjugaten.
Highly Selective Hydroboration of Alkenes, Ketones and Aldehydes Catalyzed by a Well‐Defined Manganese Complex
Authors: Zhang Guoqi , Zeng Haisu , Wu Jing , Yin Zhiwei , Zheng Shengping , Fettinger James C. 
Published: October 2016

AbstractWell‐defined manganese complexes based on inexpensive, readily available ligands, 2,2′:6′,2′′‐terpyridine and its derivatives have been prepared and employed for the selective hydroboration of alkenes, ketones and aldehydes. Highly Markovnikov regioselective hydroboration of styrenes as well as excellent chemoselective hydroboration of ketones over alkenes were achieved, for the first time, by an earth‐abundant manganese catalyst.
Optimized Tetrazine Derivatives for Rapid Bioorthogonal Decaging in Living Cells
Authors: Fan Xinyuan , Ge Yun , Lin Feng , Yang Yi , Zhang Gong , Ngai William Shu Ching , Lin Zhi , Zheng Siqi , Wang Jie , Zhao Jingyi , Li Jie , Chen Peng R. 
Published: October 2016

AbstractThe inverse‐electron‐demand Diels–Alder (iDA) reaction has recently been repurposed as a bioorthogonal decaging reaction by accelerating the elimination process after an initial cycloaddition between trans‐cyclooctene (TCO) and tetrazine (TZ). Herein, we systematically surveyed 3,6‐substituted TZ derivatives by using a fluorogenic TCO–coumarin reporter followed by LC‐MS analysis, which revealed that the initial iDA cycloaddition step was greatly accelerated by electron‐withdrawing groups (EWGs) while the subsequent elimination step was strongly suppressed by EWGs. In addition, smaller substituents facilitated the decaging process. These findings promoted us to design and test unsymmetric TZs bearing an EWG group and a small non‐EWG group at the 3‐ and 6‐position, respectively. These TZs showed remarkably enhanced decaging rates, enabling rapid iDA‐mediated protein activation in living cells.
Schwefelylide durch (3+2)‐Cycloaddition von Arinen mit Vinylsulfiden – stereoselektive Synthese hoch substituierter Alkene
Authors: Li Yuanming , Mück‐Lichtenfeld Christian , Studer Armido 
Published: October 2016

AbstractDie Reaktion von in situ erzeugten Arinen mit Vinylsulfiden liefert benzanellierte Schwefelylide in einer (3+2)‐Cycloaddition. Die intermediär auftretenden Ylide lassen sich mit Elektrophilen abfangen (über Protontransfer oder durch erneute Arinaddition) und nach anschließender β‐Eliminierung mit hoher Stereoselektivität in di‐, tri‐ oder tetra‐substituierte Alkene überführen. Experimentelle Untersuchungen und DFT‐Rechnungen beleuchten den Mechanismus dieser Kaskadenreaktion.
Starker Hinweis auf einen Phosphanoxylkomplex: Bildung, Bindung und Reaktivität komplexgebundener P‐Analoga von Nitroxiden
Authors: Heurich Tobias , Nesterov Vitaly , Schnakenburg Gregor , Qu Zheng‐Wang , Grimme Stefan , Hazin Khatera , Gates Derek P. , Engeser Marianne , Streubel Rainer 
Published: October 2016

AbstractDer einfache Zugang zu [W(CO)5(Ph2P‐OTEMP)] wurde in dieser Studie benutzt, um transiente Phosphanoxylkomplexe [MLn(R2PO)] zu erzeugen und ihre Eigenschaften und Reaktionen zu untersuchen. Der erste solche Komplex konnte durch das Tritylradikal in einer Heterokupplungsreaktion abgefangen werden. Weiterhin wurde gezeigt, dass P‐Nitroxylkomplexe als Radikalinitiatoren in der Styrolpolymerisation wirken können. Die Frage nach P‐O‐ oder O‐N‐Bindungshomolyse und der erste Schritt der Polymerisation wurden mittels DFT‐Methoden untersucht.
An Electron‐Deficient Azacoronene Obtained by Radial π Extension
Authors: Żyła‐Karwowska Marika , Zhylitskaya Halina , Cybińska Joanna , Lis Tadeusz , Chmielewski Piotr J. , Stępień Marcin 
Published: October 2016

AbstractA hexapyrrolohexaazacoronene derivative containing 37 fused rings, the largest such system to date, was obtained from a naphthalenomonoimide–pyrrole hybrid in a concise and efficient synthesis. This large heterocycle is electron‐deficient and shows extended redox activity, spanning at least 13 oxidation levels, but is otherwise chemically stable. Radial expansion of the π system creates a chromophore characterized by strong fluorescence and solvatochromism in the neutral state, and strong near‐infrared absorption in the charged states. Additionally, the enlarged and ruffled aromatic surface supports a unique self‐assembly mode in the crystal, leading to the formation of highly solvated organic clathrates.
Platinum Alloy Tailored All‐Weather Solar Cells for Energy Harvesting from Sun and Rain
Authors: Tang Qunwei , Duan Yanyan , He Benlin , Chen Haiyan 
Published: October 2016

AbstractSolar cells that can harvest energy in all weathers are promising in solving the energy crisis and environmental problems. The power outputs are nearly zero under dark conditions for state‐of‐the‐art solar cells. To address this issue, we present herein a class of platinum alloy (PtMx, M=Ni, Fe, Co, Cu, Mo) tailored all‐weather solar cells that can harvest energy from rain and realize photoelectric conversion under sun illumination. By tuning the stoichiometric Pt/M ratio and M species, the optimized solar cell yields a photoelectric conversion efficiency of 10.38 % under simulated sunlight irradiation (AM 1.5, 100 mW cm−2) as well as current of 3.90 μA and voltage of 115.52 μV under simulated raindrops. Moreover, the electric signals are highly dependent on the dripping velocity and the concentration of simulated raindrops along with concentrations of cation and anion.
Catalytic Asymmetric Allylboration of Indoles and Dihydroisoquinolines with Allylboronic Acids: Stereodivergent Synthesis of up to Three Contiguous Stereocenters
Authors: Alam Rauful , Diner Colin , Jonker Sybrand , Eriksson Lars , Szabó Kálmán J. 
Published: October 2016

AbstractThe catalytic asymmetric allylboration of cyclic imines with γ,γ‐disubstituted allylboronic acids provides products with adjacent stereocenters in high yield and stereoselectivity. Various electrophiles, including 3,4‐dihydroisoquinolines and indoles, were prenylated in a fully stereodivergent fashion by switching the E/Z geometry of the allylboronate and/or the enantiomer of the BINOL catalyst. 3‐Methylindole provided products with three adjacent stereocenters with high stereoselectivity in one synthetic operation.
Arrangement of Renal Arteries in Guinea Pig
Authors: Mazensky David , Flesarova Slavka 
Published: October 2016

ABSTRACTThe aim of this study was to describe origin, localization, and variations of renal arteries in guinea pig. The study was carried out on 26 adult guinea pigs. We prepared corrosion casts of the guinea pig arterial system. Batson's corrosion casting kit no. 17 was used as the casting medium. In 57.7% of specimens, a. renalis dextra was present as a single vessel with different level of its origin from aorta abdominalis. In 38.5% of specimens, two aa. renales dextrae were present with variable origin and arrangement. The presence of three aa. renales dextrae we found in one specimen. In 76.9% of specimens, a. renalis sinistra was present as a single vessel with different level of its origin from aorta abdominalis and variable arrangement. In 23.1% of specimens, we found two aa. renales sinistrae with variable origin and arrangement. The anatomical knowledge of the renal arteries, and its variations are of extreme importance for the surgeon that approaches the retroperitoneal region in several experiments, results of which are extrapolated in human. This is the first work dealing with the description of renal arteries arrangement in guinea pig. Anat Rec, 300:556–559, 2017. © 2016 Wiley Periodicals, Inc.
Competency‐based education: The employers' perspective of higher education
Authors: Henrich Joy 
Published: October 2016

BackgroundThis article presents the results of a recent research study conducted to understand how employers viewed degrees earned through competency‐based education programs and, specifically, how employers perceived graduates from these programs for hiring.MethodsThis two‐phase, sequential mixed methods study explored whether employers valued such degrees and whether they considered job applicants possessing credentials from competency‐based education programs to be equally academically prepared for the workplace as candidates who had graduated from traditional, credit‐hour‐based programs. The participants in both phases of this study were human resource professionals and hiring managers from a range of business models, industries, and employee population sizes who were members of a targeted human resource organization.FindingsThe number one finding of the study was the lack of familiarity that employers possess of the CBE model, but it is clear that employers have strong views of what they require from new hires and new college graduates. The research results also indicated that employers have an interest in learning more about the CBE model of education.ConclusionsEmployers would like to have a voice in identifying what skills and competencies are needed by their workforces, and they believe it is in a college's best interest to seek out their input. They have noted that credentials from competency‐based programs can be of value to their organizations if the competencies that a student masters are aligned with employer needs.
Transcatheter aortic valve implantation with the direct flow medical prosthesis: Impact of native aortic valve calcification degree on outcomes
Authors: D'Ancona Giuseppe , Agma Hüseyin U. , Ince Hüseyin , El‐Achkar Gihan , Dißmann Martin , Ortak Jasmin , Kische Stephan 
Published: October 2016

ObjectivesWe present our single center experience with the direct flow medical (DFM) prosthesis addressing the impact of native aortic valve (AV) calcification degree on outcomes.BackgroundThe DFM® has been introduced for transcatheter aortic valve implantation (TAVI). The valve has a nonmetallic and inflatable support structure.MethodsPatients were divided in two groups according to preoperative cardiac computed tomography (CT): group I moderate calcification and group II heavy calcification of the total AV area. We evaluated 118 patients: 53 (45%) group I and 65 (55%) group II.ResultsPreoperative trans‐AV gradient and calcification extension across the aortic unit were significantly higher in group II (P = 0.008 and P < 0.0001). CT perimeter derived annular diameter (group I 24.7 ± 2.1 mm vs. group II 24.8 ± 1.9; P = 0.6) and implanted prosthesis size (group I 26.1 ± 1.5 mm vs. group II 25.7 ± 1.5; P = 0.1) were similar. Hemodynamics were similar: mean gradient 16.1 ± 5.9 mm Hg (group I) vs. 17.3 ± 6.5 mm Hg (group II) (P = 0.3). Total aortic regurgitation (AR) was mild in 5.7% in group I and 20% in group II (P = 0.03). None developed moderate/severe AR. Heavy AV calcification was the sole independent determinant for mild regurgitation (P = 0.02; OR = 7; 95% CI: 1.2–37.6). Follow‐up (289 days; 40–760 days) estimated survival was 88.1% (group I) and 93.8% (group II) (P = 0.3).ConclusionsIndependent of AV calcification degree, adequate sizing and implantation can be achieved with the DFM®. Although higher burden of calcification increases the rate of mild AR, no patient developed moderate and severe AR. Short‐term estimated survival was not influenced by calcification degree. © 2016 Wiley Periodicals, Inc.
Trans‐catheter aortic valve implantation with the direct flow medical prosthesis: Single center short‐term clinical and echocardiographic outcomes
Authors: Kische Stephan , D'Ancona Giuseppe , Agma Hüseyin U. , El‐Achkar Gihan , Dißmann Martin , Ortak Jasmin , Ince Hüseyin 
Published: October 2016

ObjectivesTo analyze our single center experience with the Direct Flow Medical (DFM).BackgroundThe DFM has been recently introduced to the market and large real world experiences are lacking.MethodsA total of 126 patients with severe aortic valve stenosis (AVS) were treated by the same team from March 2013 to May 2015. Device success and procedural safety were classified, according to valve academic research consortium (VARC) criteria, for the entire cohort, including patients treated in the early phases of our learning curve.ResultsClinical and trans‐thoracic echocardiography follow‐up was performed (median duration 279 days; 36–761 days). Mean age was 80.9 ± 5.5 years and median logistic Euro‐SCORE was 15.9 (5.5–84.2). Cardiovascular 30‐day mortality was 4.8% (6/126), device success 89.6% (113/126), and early safety 85.7% (108/126). At discharge, no aortic regurgitation (AR) was present in 85.7% and mild AR in 14.3% of the patients. Estimated 1‐year follow‐up survival was 91%. At follow‐up, no AR was present in 87.3%, mild AR in 10.9%, and moderate AR in 1.8%. Mean gradient of 15.1 ± 6.3 mm Hg and prosthesis effective orifice area of 1.6 ± 0.6 cm2 were reported.ConclusionsIn this single center experience, the DFM valve showed satisfactory clinical and hemodynamic results. Short‐term follow‐up confirmed the consistent clinical results, with low rates of AR and acceptable trans‐prosthetic gradients and prosthetic effective orifice area. © 2016 Wiley Periodicals, Inc.
Renewable p‐Xylene from 2,5‐Dimethylfuran and Ethylene Using Phosphorus‐Containing Zeolite Catalysts
Authors: Cho Hong Je , Ren Limin , Vattipalli Vivek , Yeh Yu‐Hao , Gould Nicholas , Xu Bingjun , Gorte Raymond J. , Lobo Raul , Dauenhauer Paul J. , Tsapatsis Michael , Fan Wei 
Published: October 2016

Abstractp‐Xylene is a major commodity chemical used for the production of polyethylene terephthalate, a polymer with applications in polyester fibers, films, and bottles. The Diels–Alder cycloaddition of 2,5‐dimethylfuran and ethylene and the subsequent dehydration of the cycloadduct intermediate is an attractive reaction pathway to produce renewable p‐xylene from biomass feedstocks. However, the highest yields reported previously do not exceed 75 %. We report that P‐containing zeolite Beta is an active, stable, and selective catalyst for this reaction with an unprecedented p‐xylene yield of 97 %. It can catalyze the dehydration reaction selectively from the furan‐ethylene cycloadduct to p‐xylene without the production of alkylated and oligomerized products. This behavior is distinct from that of Al‐containing zeolites and other solid phosphoric acid catalysts and establishes a commercially attractive process for renewable p‐xylene production.
Carbon Composites for a High‐Energy Lithium–Sulfur Battey with a Glyme‐Based Electrolyte
Authors: Carbone Lorenzo , Peng Jing , Agostini Marco , Gobet Mallory , Devany Matthew , Scrosati Bruno , Greenbaum Steve , Hassoun Jusef 
Published: October 2016

AbstractA comparative study of sulfur composites using carbon of various natures, namely, graphite, mesocarbon microbeads, and multi‐walled carbon nanotubes, is performed in lithium battery design and evaluation. Morphological and structural analyses, by means of SEM and XRD, cyclic voltammetry and galvanostatic cycling in lithium cells are employed for characterization of the materials. Tetraethylene glycol dimethyl ether containing lithium trifluoromethansulfonate is considered the preferred electrolyte for performing the electrochemical tests. Prior to use in cells, the electrolyte characteristics in terms of 1H, 7Li, and 19F nuclei self‐diffusion coefficients, ionic conductivity, and ionic association degree are studied by combining NMR and impedance spectroscopy. The best lithium–sulfur composite reported herein achieves a capacity higher than 500 mAh g−1 over 140 cycles with no sign of dendrite formation or failure. This performance is considered sufficiently suitable for the development of high‐energy lithium batteries, in particular, considering the expected safety of the cells by employing a nonflammable glyme electrolyte instead of a conventional carbonate‐based one.
Mesoporous γ‐Iron Oxide Nanoparticles for Magnetically Triggered Release of Doxorubicin and Hyperthermia Treatment
Authors: Benyettou Farah , Ocadiz Flores Jaen Alonso , Ravaux Florent , Rezgui Rachid , Jouiad Mustapha , Nehme Samer I. , Parsapur Rajesh Kumar , Olsen John‐Carl , Selvam Parasuraman , Trabolsi Ali 
Published: October 2016

AbstractMesoporous iron‐oxide nanoparticles (mNPs) were prepared by using a modified nanocasting approach with mesoporous carbon as a hard template. mNPs were first loaded with doxorubicin (Dox), an anticancer drug, and then coated with the thermosensitive polymer Pluronic F108 to prevent the leakage of Dox molecules from the pores that would otherwise occur under physiological conditions. The Dox‐loaded, Pluronic F108‐coated system (Dox@F108‐mNPs) was stable at room temperature and physiological pH and released its Dox cargo slowly under acidic conditions or in a sudden burst with magnetic heating. No significant toxicity was observed in vitro when Dox@F108‐mNPs were incubated with noncancerous cells, a result consistent with the minimal internalization of the particles that occurs with normal cells. On the other hand, the drug‐loaded particles significantly reduced the viability of cervical cancer cells (HeLa, IC50=0.70 μm), wild‐type ovarian cancer cells (A2780, IC50=0.50 μm) and Dox‐resistant ovarian cancer cells (A2780/AD, IC50=0.53 μm). In addition, the treatment of HeLa cells with both Dox@F108‐mNPs and subsequent alternating magnetic‐field‐induced hyperthermia was significantly more effective at reducing cell viability than either Dox or Dox@F108‐mNP treatment alone. Thus, Dox@F108‐mNPs constitute a novel soft/hard hybrid nanocarrier system that is highly stable under physiological conditions, temperature‐responsive, and has chemo‐ and thermotherapeutic modes of action.
Detailed Structural Analysis of a Self‐Assembled Vesicular Amphiphilic NCN‐Pincer Palladium Complex by Using Wide‐Angle X‐Ray Scattering and Molecular Dynamics Calculations
Authors: Hamasaka Go , Muto Tsubasa , Andoh Yoshimichi , Fujimoto Kazushi , Kato Kenichi , Takata Masaki , Okazaki Susumu , Uozumi Yasuhiro 
Published: October 2016

AbstractWide‐angle X‐ray scattering experiments and all‐atomistic molecular dynamics calculations were performed to elucidate the detailed structure of bilayer vesicles constructed by self‐assembly of an amphiphilic palladium NCN‐pincer complex. We found an excellent agreement between the experimental and calculated X‐ray spectra, and between the membrane thickness determined from a TEM image and that calculated from an electron‐density profile, which indicated that the calculated structure was highly reliable. The analysis of the simulated bilayer structure showed that in general the membrane was softer than other phospholipid bilayer membranes. In this bilayer assemblage, the degree of alignment of complex molecules in the bilayer membrane was quite low. An analysis of the electron‐density profile shows that the bilayer assemblage contains a space through which organic molecules can exit. Furthermore, the catalytically active center is near this space and is easily accessible by organic molecules, which permits the bilayer membrane to act as a nanoreactor. The free energy of permeation of water through the bilayer membrane of the amphiphilic complex was 12 kJ mol−1, which is much lower than that for phospholipid bilayer membranes in general. Organic molecules are expected to pass though the bilayer membrane. The self‐assembled vesicles were shown to be catalytically active in a Miyaura–Michael reaction in water.
Mechanistic Investigation of Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Thiophene–Pyridine Biaryl Monomers with the Aid of Model Reactions
Authors: Tokita Yu , Katoh Masaru , Ohta Yoshihiro , Yokozawa Tsutomu 
Published: October 2016

AbstractWe have investigated the requirements for efficient Pd‐catalyzed Suzuki–Miyaura catalyst‐transfer condensation polymerization (Pd‐CTCP) reactions of 2‐alkoxypropyl‐6‐(5‐bromothiophen‐2‐yl)‐3‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)pyridine (12) as a donor–acceptor (D–A) biaryl monomer. As model reactions, we first carried out the Suzuki–Miyaura coupling reaction of X–Py–Th–X′ (Th=thiophene, Py=pyridine, X, X′=Br or I) 1 with phenylboronic acid ester 2 by using tBu3PPd0 as the catalyst. Monosubstitution with a phenyl group at Th‐I mainly took place in the reaction of Br–Py–Th–I (1 b) with 2, whereas disubstitution selectively occurred in the reaction of I–Py–Th–Br (1 c) with 2, indicating that the Pd catalyst is intramolecularly transferred from acceptor Py to donor Th. Therefore, we synthesized monomer 12 by introduction of a boronate moiety and bromine into Py and Th, respectively. However, examination of the relationship between monomer conversion and the Mn of the obtained polymer, as well as the matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectra, indicated that Suzuki–Miyaura coupling polymerization of 12 with (o‐tolyl)tBu3PPdBr initiator 13 proceeded in a step‐growth polymerization manner through intermolecular transfer of the Pd catalyst. To understand the discrepancy between the model reactions and polymerization reaction, Suzuki–Miyaura coupling reactions of 1 c with thiopheneboronic acid ester instead of 2 were carried out. This resulted in a decrease of the disubstitution product. Therefore, step‐growth polymerization appears to be due to intermolecular transfer of the Pd catalyst from Th after reductive elimination of the Th‐Pd‐Py complex formed by transmetalation of polymer Th–Br with (Pin)B–Py–Th–Br monomer 12 (Pin=pinacol). Catalysts with similar stabilization energies of metal–arene η2‐coordination for D and A monomers may be needed for CTCP reactions of biaryl D–A monomers.