bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rhodium‐Catalyzed Addition of Aryl Boronic Acids to 2,2‐Disubstituted Malononitriles
Authors: Malapit Christian A. , Caldwell Donald R. , Luvaga Irungu K. , Reeves Jonathan T. , Volchkov Ivan , Gonnella Nina C. , Han Zhengxu S. , Busacca Carl A. , Howell Amy R. , Senanayake Chris H. 
Published: May 2017

Abstractβ‐Ketonitriles bearing a quaternary carbon at the 2‐position were prepared through Rh‐catalyzed addition of aryl boronic acids to 2,2‐disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro‐Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β‐ketonitriles. The products could be further derivatized to valuable chiral α,α‐disubstituted‐β‐aminonitriles through addition reactions to the corresponding N‐tert‐butanesulfinyl imines.
Substituenteneffekte auf Stapelwechselwirkungen parallel verschobener π‐Systeme: der Abstand ist entscheidend
Authors: Riwar Leslie‐Joana , Trapp Nils , Kuhn Bernd , Diederich François 
Published: May 2017

AbstractWirt‐Gast‐Systeme aus substituierten Rebek‐Imiden als Rezeptoren und 2,6‐Di(isobutyramido)pyridin als Ligand wurden zur Untersuchung von Substituenteneffekten auf π‐π‐Stapelwechselwirkungen parallel verschobener π‐Systeme eingesetzt. Änderungen des intermolekularen Abstands zwischen dem para‐Substituenten der aromatischen Plattform des Imid‐Rezeptors und dem Pyridinring des Gasts resultierten in stark unterschiedlichen Substituenteneffekten. Eine kurze Ethin‐1,2‐diyl‐Brücke zwischen Rebek‐Imid und aromatischer Plattform führte zu einer partiellen Überlappung des Gasts mit dem Substituenten, die unabhängig von dessen elektronischen Eigenschaften zu einer verstärkten π‐π‐Stapelwechselwirkung führte (Wheeler‐Houk‐Modell). Ersatz der Ethin‐1,2‐diyl‐ durch die längere Buta‐1,3‐diin‐1,4‐diyl‐Brücke verhinderte direkte Substituent‐Gast‐Wechselwirkungen durch den Raum. Es wurde eine lineare Korrelation zwischen logKa (Ka=Assoziationskonstante) und dem Hammett‐Substituentenparameter σpara gefunden, wodurch die Vorhersage des Hunter‐Sanders‐Modells experimentell bestätigt wurde.
Generierung einer kleinen HOMO‐LUMO‐Lücke und intramolekulare C‐H‐Borylierung durch Diboren‐Anthracen‐Orbitalinterkalation
Authors: Wang Sunewang R. , Arrowsmith Merle , Böhnke Julian , Braunschweig Holger , Dellermann Theresa , Dewhurst Rian D. , Kelch Hauke , Krummenacher Ivo , Mattock James D. , Müssig Jonas H. , Thiess Torsten , Vargas Alfredo , Zhang Jiji 
Published: May 2017

AbstractDiboren 1 wurde durch Reduktion einer Mischung aus 1,2‐Di‐9‐anthryl‐1,2‐dibromdiboran(4) (6) und Trimethylphosphan mit Kaliumgraphit dargestellt. Die Molekülstruktur von 1 zeigt, dass die Anthrylringe zueinander parallel und in Bezug auf das Diboren‐π(B=B)‐System orthogonal angeordnet sind. Diese verdrehte Konformation ohne signifikante Konjugation erlaubt eine Interkalation des relativ hoch liegenden π(B=B)‐Orbitals mit dem tief liegenden π*‐Orbital der Anthryl‐Einheit, was zu einer kleinen HOMO‐LUMO‐Lücke und letztlich zur C‐H‐Borylierung des Anthryl‐Liganden führt. Die HOMO‐LUMO‐Energielücke wurde durch den Beginn der Absorptionsbande bei der längsten Wellenlänge im UV‐vis‐Spektrum auf 1.57 eV geschätzt (THF, λonset=788 nm). Mit elementarem Selen ließ sich Verbindung 1 quantitativ zum Diboraseleniran 8 umsetzen. Durch ein weiteres Äquivalent Selen wird unter oxidativer Abspaltung eines Phosphan‐Liganden und Spaltung der B‐B‐ und C1‐H‐Bindungen das cyclische 1,9‐Diborylanthracen 9 erhalten.
Catalytic Asymmetric [3+1]‐Cycloaddition Reaction of Ylides with Electrophilic Metallo‐enolcarbene Intermediates
Authors: Deng Yongming , Massey Lynée A. , Zavalij Peter Y. , Doyle Michael P. 
Published: May 2017

AbstractThe first asymmetric [3+1]‐cycloaddition was successfully achieved by copper(I) triflate/double‐sidearmed bisoxazoline complex catalyzed reactions of β‐triisopropylsilyl‐substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio‐ and diastereoselectivities (up to 99 % ee, and >20:1 d.r.). Additionally, the [3+1]‐cycloaddition of catalytically generated metallo‐enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex.
Temperature‐Driven Planar Chirality Switching of a Pillar[5]arene‐Based Molecular Universal Joint
Authors: Yao Jiabin , Wu Wanhua , Liang Wenting , Feng Yujun , Zhou Dayang , Chruma Jason J. , Fukuhara Gaku , Mori Tadashi , Inoue Yoshihisa , Yang Cheng 
Published: May 2017

AbstractThe study of an enantiopure bicyclic pillar[5]arene‐based molecular universal joint (MUJ) by single‐crystal X‐ray diffraction allowed for the first time the unequivocal assignment of the absolute configuration of a planar chiral pillar[5]arene by circular dichroism spectroscopy. Crucially, the absolute configuration of the MUJ was switched reversibly by temperature, with an accompanying sign inversion of the anisotropy factor that varied by as much as 0.03, which is the largest value ever reported. Mechanistically, the reversible chirality switching of the MUJ is driven by the threading/dethreading motion of the fused ring and hence is dependent on both the size and nature of the ring and the solvent employed, reflecting the critical balance between the self‐complexation of the ring by pillar[5]arene, the solvation to the excluded ring, and the inclusion of solvent molecules in the cavity.
Single‐Molecule Photoactivation FRET: A General and Easy‐To‐Implement Approach To Break the Concentration Barrier
Authors: Peng Sijia , Sun Ruirui , Wang Wenjuan , Chen Chunlai 
Published: May 2017

AbstractSingle‐molecule fluorescence resonance energy transfer (sm‐FRET) has become a widely used tool to reveal dynamic processes and molecule mechanisms hidden under ensemble measurements. However, the upper limit of fluorescent species used in sm‐FRET is still orders of magnitude lower than the association affinity of many biological processes under physiological conditions. Herein, we introduce single‐molecule photoactivation FRET (sm‐PAFRET), a general approach to break the concentration barrier by using photoactivatable fluorophores as donors. We demonstrate sm‐PAFRET by capturing transient FRET states and revealing new reaction pathways during translation using μm fluorophore labeled species, which is 2–3 orders of magnitude higher than commonly used in sm‐FRET measurements. sm‐PAFRET serves as an easy‐to‐implement tool to lift the concentration barrier and discover new molecular dynamic processes and mechanisms under physiological concentrations.
Achiral Pyridine Ligand‐Enabled Enantioselective Radical Oxytrifluoromethylation of Alkenes with Alcohols
Authors: Cheng Yong‐Feng , Dong Xiao‐Yang , Gu Qiang‐Shuai , Yu Zhang‐Long , Liu Xin‐Yuan 
Published: May 2017

AbstractA conceptually novel strategy with achiral pyridine as the ancillary ligand to stabilize high‐valent copper species for the first asymmetric radical oxytrifluoromethylation of alkenes with alcohols under CuI/phosphoric acid dual‐catalysis has been developed. The transformation features mild reaction conditions, a remarkably broad substrate scope and excellent functional group tolerance, offering an efficient approach to a wide range of trifluoromethyl‐substituted tetrahydrofurans bearing an α‐tertiary stereocenter with excellent enantioselectivity. Mechanistic studies support the presumed role of the achiral pyridine as a coordinative ligand on copper metal to stabilize the key transient reaction species involved in the asymmetric induction process.
Discovery of EGF Receptor Inhibitors That Are Selective for the d746‐750/T790M/C797S Mutant through Structure‐Based de Novo Design
Authors: Park Hwangseo , Jung Hoi‐Yun , Mah Shinmee , Hong Sungwoo 
Published: May 2017

AbstractNext‐generation epidermal growth factor receptor (EGFR) inhibitors against the d746‐750/T790M/C797S mutation were discovered through two‐track virtual screening and de novo design. A number of nanomolar inhibitors were identified using 2‐aryl‐4‐aminoquinazoline as the molecular core and the modified binding energy function involving a proper dehydration term, which provides important structural insight into the key principles for high inhibitory activities against the d746‐750/T790M/C797S mutant. Furthermore, some of these EGFR inhibitors showed a greater than 1000‐fold selectivity for the d746‐750/T790M/C797S mutant over the wild type, as well as nanomolar activity against the mutant.
Dielectric and thermal behaviors of fluorine‐containing dianhydride‐modified polybenzoxazine: A molecular design flexibility
Authors: Pattharasiriwong Patcharat , Jubsilp Chanchira , Mora Phattarin , Rimdusit Sarawut 
Published: May 2017

ABSTRACTFluorine‐containing copolybenzoxazines were successfully prepared by reacting bisphenol‐AF/aniline‐based benzoxazine resin (BAF‐a) with 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) in N,N‐dimethylacetamide solvent. The dielectric and thermal properties as well as flexibility of the resulting copolymer films were investigated. The incorporation of fluorine groups into polybenzoxazine was found to substantially decrease the dielectric constant of the resulting copolybenzoxazine to as low as 2.6. The formation of ester linkages between the hydroxyl groups in the poly(BAF‐a) and the carbonyl groups in the 6FDA resulted in substantially enhanced flexibility of the copolybenzoxazines. Moreover, the copolymers showed superior degradation temperature and significant improvement in char yield, up to 464 °C and 56%, respectively. The glass‐transition temperature of the copolybenzoxazines was increased with increasing dianhydride content and exhibited a maximum value of 290 °C at 2.5/1 mole ratio of poly(BAF‐a) to 6FDA. Therefore, the fluorine‐containing dianhydride‐modified polybenzoxazines are appropriate for applications as polymeric films for coatings and as a good electrical insulation material with high thermal resistance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45204.
A Computational Study of a Single‐Walled Carbon‐Nanotube‐Based Ultrafast High‐Capacity Aluminum Battery
Authors: Bhauriyal Preeti , Mahata Arup , Pathak Biswarup 
Published: May 2017

AbstractExploring suitable electrode materials is a fundamental step toward developing Al batteries with enhanced performance. In this work, we explore using density functional theory calculations the feasibility of single‐walled carbon nanotubes (SWNTs) as a cathode material for Al batteries. Carbon nanotubes with hollow structures and large surface area are able to overcome the difficulty of activating the opening of interlayer spaces as observed in graphite electrode during the first intercalation cycle. Our results show that AlCl4 binds strongly with the SWNT to result in an energetically and thermally stable AlCl4‐adsorbed SWNT system. Diffusion calculations show that the SWNT system allows ultrafast diffusion of AlCl4 with a more favorable inner surface diffusion than outer surface diffusion. Our charge‐density difference and Bader atomic charge analysis confirm the oxidation of SWNT upon adsorption of AlCl4, which shows a similar behavior to the previously studied graphite cathode. The average open‐circuit voltage and AlCl4 storage capacity increases with increasing SWNT diameter and can be as high as 1.96 V and 275 mA h g−1 in (25,25) SWNT relative to graphite (70 mA h g−1). All of these properties show that SWNTs are a potential cathode material for high‐performance Al batteries and should be explored further.
Nitrogen‐Doped Graphitic Porous Carbon Nanosheets Derived from In Situ Formed g‐C3N4 Templates for the Oxygen Reduction Reaction
Authors: Li Qi , Xu Dan , Ou Xu , Yan Feng 
Published: May 2017

AbstractHeteroatom‐doped carbon materials have been considered as potential substitutes for Pt‐based electrocatalysts for the oxygen reduction reaction (ORR) in alkaline fuel cells. Here we report the synthesis of oxygen‐containing nitrogen‐doped carbon (ONC) nanosheets through the carbonization of a mixture that contained glucose and dicyandiamide (DCDA). In situ formed graphitic carbon nitride (g‐C3N4) derived from DCDA provided a nitrogen‐rich template, thereby facilitating the formation of ONC nanosheets. The resultant ONC materials with high nitrogen content, high specific surface areas, and highly mesoporous total volume displayed excellent electrochemical performance, including a similar ORR onset potential, half‐potential, a higher diffusion‐limited current, and excellent tolerance to methanol than that of the commercial Pt/C catalyst, respectively. Moreover, the ONC‐850 nanosheet displayed high long‐term durability even after 1000 cycles as well as a high electron transfer number of 3.92 (4.0 for Pt/C). Additionally, this work provides deeper insight into these materials and a versatile strategy for the synthesis of cost‐effective 2D N‐doped carbon electrocatalysts.
Structural identification of degradants of moexipril by LC–MS/MS
Authors: Challa Purushotham Reddy , K. Ramakrishna , K. M. V. Narayana Rao 
Published: May 2017

AbstractA gradient LC–MS method was developed for the identification and characterization of degradants of moexipril using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS). Moexipril was subjected to hydrolysis (acid, base and neutral), oxidation, photolytic and thermal degradation conditions as mentioned in ICH guidelines Q1A (R2). The drug degraded under hydrolysis, oxidation and photolytic conditions, but it was stable under thermal conditions. In total, five degradants were formed and separated on an Agilent XDB C‐18 column (4.6 × 150 mm, 5 μm) in a gradient elution method. Four degradants (D1, D2, D4 and D5) under acidic conditions, three degradants (D2, D3 and D4) under basic conditions and three degradants (D1, D4 and D5) under neutral and oxidative stress conditions were formed. In addition, two degradants (D4 and D5) were formed under photolytic stress conditions. To elucidate the structures of degradants, fragmentation of moexipril and its degradants was studied using LC–MS/MS experiments and accurate mass measurements (HRMS) data. The fragment ions in the product ion tandem mass spectra of all the degradants were compared with those of moexipril and assigned the probable structures for the degradants.
Suitability of selected chromatographic columns for analysis of fatty acids in dialyzed patients
Authors: Pazda Magdalena , Stepnowski Piotr , Sledzinski Tomasz , Chmielewski Michal , Mika Adriana 
Published: May 2017

AbstractGas chromatography–mass spectrometry is a preferred method for fatty acid (FA) analysis in biofluids from patients with metabolic diseases. Complex characteristics of FAs make their analysis particularly challenging. Selection of an appropriate chromatographic column is particularly important component of the process as it provides optimal separation and detection of possibly all FAs present in the sample. However, no accurate protocol for comparative evaluation of capillary columns for the analysis of whole serum FA profile in patients with chronic kidney disease (CKD) has been developed thus far. Therefore, in the present study four columns were examined to select the one providing optimal separation and determination of FA profiles in this group of patients. Moreover, serum FA profiles obtained with the selected column in CKD patients subjected to peritoneal dialysis and healthy controls were compared. Thirty‐seven component FAME Mix and sera from CKD patients were used to optimize chromatographic conditions and to select the most appropriate column. The ZB‐5 column turned out to be the most appropriate for the analysis of whole FA profile in CKD patients' sera. Then, this column was used to compare FA profiles in patients subjected to peritoneal dialysis and in healthy controls. The analysis demonstrated many abnormalities in the FA profile of CKD patients. Further studies involving larger groups of patients presenting with other stages of CKD are required to explain the impact of the disease progression on composition of serum FAs.
M2 macrophages induce EMT through the TGF‐β/Smad2 signaling pathway
Authors: Zhu Liangying , Fu Xiao , Chen Xiang , Han Xiaodong , Dong Ping 
Published: May 2017

AbstractIPF is characterized by fibroblast accumulation, collagen deposition, and ECM remodeling, with myofibroblasts believed to be the effector cell type. Myofibroblasts develop due to EMT of lung alveolar epithelial cells, which can be induced by TGF‐β. M2 macrophages, a macrophage subpopulation, secrete large amounts of TGF‐β. To clarify the relationship between IPF, EMT, TGF‐β, and M2 macrophages, a bleomycin‐induced pulmonary fibrosis mouse model was used. Seventeen days after mice were treated with bleomycin, the successful establishment of a pulmonary fibrosis model was confirmed by HE stain and Masson's trichrome stain. We found evidence in support of EMT, such as elevated protein levels of α‐SMA in lung tissue and decreased levels of E‐cadherin and CK‐18. Additionally, increased TGF‐β levels and TGF‐β/Smad2 signaling activation was observed. Macrophages were recruited to pulmonary alveoli. Alveolar macrophages were phenotyped and identified as M2 macrophages, with up‐regulated CD206 on the cell surfaces. For in vitro studies, we treated RAW 264.7 cells with IL‐4 for 24 h, and the cells were then utilized as M2 macrophages. TGF‐β levels increased significantly in the culture supernatant. Forty‐eight hours after lung epithelial cells (MLE‐12) were co‐cultured with the M2 macrophages, the expression of α‐SMA increased, and E‐cadherin and CK‐18 decreased. When a TGF‐β receptor inhibitor, LY2109761 was used, the EMT induced by M2 macrophages was blocked. In conclusion, we demonstrated that M2 macrophages induce EMT through the TGF‐β/Smad2 signaling pathway.
Transcatheter interventions in adults with congenital heart disease: Surveys from the Society for Cardiovascular Angiography and Interventions to identify current patterns of care and perception on training requirements
Authors: Wadia Subeer K. , Accavitti Michael J. , Morgan Gareth J. , Kenny Damien , Hijazi Ziyad M. , Jones Thomas K. , Cabalka Allison K. , McElhinney Doff B. , Kavinsky Clifford J. 
Published: May 2017

AbstractBackgroundInterventional catheterization is central to the care of Adults with Congenital Heart Disease (ACHD). Current standards for care provision and training in ACHD intervention are lacking. We sought to examine trends in current practice and training among interventionalists.MethodsWe analyzed the results of two separate international surveys in June 2016. One was sent to all active members from the Society of Cardiovascular Angiography and Interventions (SCAI) who self‐identified Structural Heart Disease or Congenital Heart Disease as a practice area. The second survey was conducted through the Pediatric Interventional Early Career Society (PICES) aimed at pediatric and adult congenital interventionalists in their first seven years after training. The total survey sample sizes were 1,535 and 112, respectively.ResultsResponse rates for the SCAI and PICES surveys were 15% (237/1,535) and 75% (84/112), respectively. Most respondents (74%) worked at institutions with pediatric and adult facilities in proximity (major medical centers). While 75% of SCAI respondents believed complex transcatheter procedures should be performed by ACHD‐trained interventionalists or multidisciplinary teams, only 32% reported such care is being provided at the present time. Most pediatric and adult cardiologists surveyed (73%) do not believe current interventional fellowships provide adequate training for proficiency in ACHD interventions.ConclusionsACHD management remains underdeveloped in relative terms, particularly in the United States. Significant gaps in interventional standards of practice and future training needs were recognized by this study. Our survey should serve as an impetus to establish training guidelines for physicians who seek to perform ACHD interventions.
Quasi‐Steady‐State Polarization Reveals the Interplay of Capacitive and Faradaic Processes in Capacitive Deionization
Authors: Holubowitch Nicolas , Omosebi Ayokunle , Gao Xin , Landon James , Liu Kunlei 
Published: May 2017

AbstractWe employ slow cyclic voltammetry to study the quasi‐steady‐state capacitive deionization (CDI) of aerated 10 mM NaCl from Vcell=−0.2 to 2 V. The method allows for the deconvolution of capacitive and faradaic processes, which are significant even at low voltage, in conjunction with pH, conductivity, dissolved oxygen (DO), and electrode potential measurements. The pH at three locations and effluent DO data identify asymmetric electrosorption in the cell configured with pristine activated carbon electrodes, where charge is irreversibly consumed to produce H+/OH− instead of reversibly adsorbing Cl−/Na+. Implementing a reference electrode resolves ion adsorption as a function of the individual potential at each electrode. Near‐electrode pH probes reveal pH environments that diverge by up to 8 units during cell polarization and allow more accurate calculation of faradaic redox potentials in a flow‐by CDI cell. In the aerated NaCl solution that will be relevant to industrial‐scale water treatment, we find that DO reduction occurs to a greater degree than Na+ adsorption at the cathode until DO removal becomes mass transfer limited at <−0.2 V vs. SHE. Two cell architectures – flow‐by and flow‐through – corroborate our findings. Finally, we reconcile all measurements to generate a map displaying how the potential is partitioned amongst the capacitive and faradaic processes occurring during CDI operation over a 2.2 V window.
Electrochemical Performance of Cobalt‐Free Nb and Ta Co‐Doped Perovskite Cathodes for Intermediate‐Temperature Solid Oxide Fuel Cells
Authors: Liang Fengli , Wang Zaixing , Wang Zhuoran , Mao Junkui , Sunarso Jaka 
Published: May 2017

AbstractThis work characterizes a series of Ta and Nb co‐doped cobalt‐free perovskite oxides with the compositions of SrNb0.2‐xTaxFe0.8O3‐δ (x=0, 0.05, 0.1, 0.15, and 0.2) for intermediate‐temperature solid oxide fuel cell (IT‐SOFC) applications. Their electronic conductivities displayed semiconducting behavior (i. e. increase with temperature rise) between 300 and 500 °C and metallic behavior (i. e. decrease with temperature rise) from 500 to 900 °C. SrNb0.1Ta0.1Fe0.8O3–δ provided the highest electrical conductivity that reaches 300 S cm−1 at 500 °C. The thermal expansion coefficients for SrNb0.2‐xTaxFe0.8O3–δ were lower than those reported for cobalt‐containing perovskite cathodes. They varied from 12.83×10−6 to 16.31×10−6 K−1 between 30 and 810 °C. Among the five tested cathodes, SrNb0.1Ta0.1Fe0.8O3–δ exhibited the lowest area‐specific resistance between 550 and 750 °C, with a minimum of 0.046 Ω cm2 at 750 °C, when tested in its symmetric cell configuration of cathode|Sm0.2Ce0.8O1.9 (SDC)|cathode. A peak power density of 1223 mW cm−2 was achieved on a SrNb0.1Ta0.1Fe0.8O3‐δ|SDC|yttria‐stabilized zirconia (YSZ)|Ni‐YSZ anode‐supported fuel cell at 700 °C. This work highlights the opportunity to create new perovskite cathode compositions with improved electrochemical performance through a co‐doping strategy.