bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection and Toxicity Evaluation of Pyrrolizidine Alkaloids in Medicinal Plants Gynura bicolor and Gynura divaricata Collected from Different Chinese Locations
Authors: Chen Jian , Lü Han , Fang Lian‐Xiang , Li Wei‐Lin , Verschaeve Luc , Wang Zheng‐Tao , De Kimpe Norbert , Mangelinckx Sven 
Published: September 2016

Two edible plants in Southeast Asia, Gynura bicolor and G. divaricata, are not only known to be nutritive but also useful as medicinal herbs. Previous phytochemical investigation of Gynura species showed the presence of hepatotoxic pyrrolizidine alkaloids (PAs), indicating the toxic risk of using these two plants. The present study was designed to analyze the distribution of PA components and tried to evaluate the preliminary toxicity of these two Gynura species. Eight samples of G. bicolor and G. divaricata from five different Chinese locations were collected and their specific PAs were qualitatively characterized by applying an UPLC/MS/MS spectrometry method. Using a pre‐column derivatization HPLC method, the total retronecine ester‐type PAs in their alkaloids extracts were quantitatively estimated as well. Finally, their genotoxicity was investigated with an effective high‐throughput screening method referred to as Vitotox™ test and their potential cytotoxicity was tested on HepG2 cells. It was found that different types of PAs were widely present in Gynura species collected from south of China. Among them, no significant genotoxic effects were detected with serial concentrations through the present in vitro assay. However, the cytotoxicity assay of Gynura plants collected from Jiangsu displayed weak activity at the concentration of 100 mg/ml. It is important to note that this research validates in part the indication that the use of Gynura species requires caution.
Formate to Oxalate: A Crucial Step for the Conversion of Carbon Dioxide into Multi‐carbon Compounds
Authors: Lakkaraju Prasad S. , Askerka Mikhail , Beyer Heidie , Ryan Charles T. , Dobbins Tabbetha , Bennett Christopher , Kaczur Jerry J. , Batista Victor S. 
Published: September 2016

AbstractThe efficient conversion of formate into oxalate could enable the industrial‐scale synthesis of multi‐carbon compounds from CO2 by C−C bond formation. We found conditions for the highly selective catalytic conversion of molten alkali formates into pure solid oxalate salts. Nearly quantitative conversion was accomplished by calcination of sodium formates with sodium hydride. A catalytic mechanism proceeding through a carbonite intermediate, generated upon H2 evolution, was supported by density functional theory calculations, Raman spectroscopy, and the observed changes in the catalytic performance upon changing the nature of the base or the reaction conditions. Whereas the conversion of formate into oxalate by using a hydroxide ion catalyst was previously studied, hydride ion catalysis and the chain reaction mechanism for the conversion involving a carbonite ion intermediate are reported herein for the first time.
Reconstruction of the Catalytic Pocket and Enzyme–Substrate Interactions To Enhance the Catalytic Efficiency of a Short‐Chain Dehydrogenase/Reductase
Authors: Li Aipeng , Ye Lidan , Yang Xiaohong , Wang Bei , Yang Chengcheng , Gu Jiali , Yu Hongwei 
Published: September 2016

AbstractTo upgrade the short‐chain dehydrogenase/reductase EbSDR8 to a powerful tool for the synthesis of antiPrelog chiral alcohols, rational design was performed by reconstructing the catalytic pocket and enzyme–substrate interactions. The resulting variants showed significantly improved catalytic efficiency (kcat/KM; kcat=turnover rate, KM=Michaelis constant) towards a series of prochiral ketones, with kcat/KM values more than 15‐fold greater than that of wildtype EbSDR8 in some cases. More importantly, none of the mutations caused an adverse effect on the stereoselectivity. The increased steric repulsion and the C−H⋅⋅⋅π interaction involving the alkyl side chain of L153 and the phenyl ring of the substrate turned out to be crucial factors connected to the enhanced enzymatic activity. This provided new insight into the role of steric hindrance and non canonical interactions in protein engineering. Furthermore, the recombinant E. coli whole cells expressing the EbSDR8 variant G94A/S153L successfully catalyzed the reduction of a high‐concentration 2,2,2‐trifluoroacetophenone. The results demonstrated the effectiveness of rational design and the applicability of the designed variants in the efficient reduction of prochiral ketones.
Fine‐Tuning the Acid–Base Properties of Boron‐Doped Magnesium Oxide Catalyst for the Selective Aldol Condensation
Authors: Pham Tu N. , Zhang Lu , Shi Dachuan , Komarneni Mallik R. , Ruiz Maria P. , Resasco Daniel E. , Faria Jimmy 
Published: September 2016

AbstractControlled incorporation of dopants into the structure of metal oxide catalysts can be used to fine‐tune their topological, chemical, and electronic properties. Conventional preparation methods (coprecipitation and impregnation) tend to produce materials with a limited extent of chemical interaction between metal oxide and dopant, small pore volume, and disconnected pore structure. Herein, we describe a combustion method to optimize both the porous structure of metal oxides and the chemical interaction with dopants. By exploiting the differences in melting points between metal oxide (MgO) and dopant (B), it is possible to create hierarchical mixed oxides with tailored chemical structure. As a model reaction, we employed the aldol condensation of acetaldehyde to crotyl alcohol, a key intermediate step in the conversion of bioethanol to 1,3‐butadiene, to show the unique characteristics of these materials. The B–Mg mixed oxide prepared by combustion exhibits an order of magnitude higher productivity of C4 products than conventional MgO and B–MgO. We anticipate that our approach could be extended to the development of other dual oxides with open structure for unrestricted diffusion and enhanced chemical interaction of acid and basic metal oxides.
Heterogeneous Palladium‐Catalyzed Hydrogen‐Transfer Cyclization of Nitroacetophenones with Benzylamines: Access to C−N Bonds
Authors: Tang Lin , Wang Pengfei , Fan Yang , Yang Xingkun , Wan Changfeng , Zha Zhenggen 
Published: September 2016

AbstractThe first Pd/C‐catalyzed oxidative C(sp3)−H bond amination of o‐nitroacetophenones with benzylamines or amino acids proceeding through C−N bond cleavage followed by C−N bond formation by a hydrogen‐transfer strategy was developed. These transformations proceeded smoothly in water to afford the desired quinazolines in moderate to good yields. This protocol has a broad substrate scope and good tolerance of air, offers excellent recyclability of the catalyst, and does not need any additional oxidant, ligand, or base; the combination of all of these factors give a new and practical avenue for multiple C−N bond formation. Moreover, a hot filtration experiment indicated that heterogeneous palladium nanoparticles during the reaction are the active species.
1,2‐Dimethoxyethane Degradation Thermodynamics in Li−O2 Redox Environments
Authors: Carboni Marco , Marrani Andrea Giacomo , Spezia Riccardo , Brutti Sergio 
Published: September 2016

AbstractThe reaction thermodynamics of the 1,2‐dimethoxyethane (DME), a model solvent molecule commonly used in electrolytes for Li−O2 rechargeable batteries, has been studied by first‐principles methods to predict its degradation processes in highly oxidizing environments. In particular, the reactivity of DME towards the superoxide anion O2− in oxygen‐poor or oxygen‐rich environments is studied by density functional calculations. Solvation effects are considered by employing a self‐consistent reaction field in a continuum solvation model. The degradation of DME occurs through competitive thermodynamically driven reaction paths that end with the formation of partially oxidized final products such as formaldehyde and methoxyethene in oxygen‐poor environments and methyl oxalate, methyl formate, 1‐formate methyl acetate, methoxy ethanoic methanoic anhydride, and ethylene glycol diformate in oxygen‐rich environments. This chemical reactivity indirectly behaves as an electroactive parasitic process and therefore wastes part of the charge exchanged in Li−O2 cells upon discharge. This study is the first complete rationale to be reported about the degradation chemistry of DME due to direct interaction with O2−/O2 molecules. These findings pave the way for a rational development of new solvent molecules for Li−O2 electrolytes.
Recent Advances in the Synthesis of SCF2H‐ and SCF2FG‐Containing Molecules
Authors: Xiong Heng‐Ying , Pannecoucke Xavier , Besset Tatiana 
Published: September 2016

AbstractIn recent years, much interest has been paid to difluoromethylthiolated molecules as the “SCF2” moiety is a key motif in drug and agrochemical research. Consequently, the development of versatile strategies for the selective synthesis of SCF2H‐ and SCF2FG‐containing molecules (FG=functional group) has attracted a lot of attention and inspired the scientific community to design new tools. This Minireview highlights the major progress made in this field. Particularly, methodologies developed for the difluoromethylation of sulfur‐containing molecules and the direct construction of C−SCF2 bonds in various classes of compounds are showcased and discussed.
Constructing a Nonfluorescent Conformation of AIEgen: A Tetraphenylethene Embedded in the Calix[4]arene's Skeleton
Authors: Han Bin , Wang Xi , Gao Yan , Bai Ming 
Published: September 2016

AbstractTwo novel 1,1‐diphenylmethylidene decorated calix[4]arenes, (Calix‐DPE(OCH3)4 and Calix‐DPE(OH)4), were designed and prepared. The tetraphenylethene (TPE) unit is embedded in the calix[4]arenes skeleton, so the conformation of tetraphenylethene unit is significantly affected by the conformation of calix[4]arene. Unlike the Calix‐DPE(OCH3)4, the Calix‐DPE(OH)4 does not show the aggregation‐induced emission (AIE) phenomena in solution or the crystal state because of the presence of intramolecular hydrogen bonding, which leads to a cone conformation for the calix[4]arene skeleton in which the embedded phenyl rings of the TPE have to take an almost perpendicular configuration to the C=C bond. This result provides direct evidence that the maximal cross‐chromophore π‐conjugation within the tetraphenylethene is one of the prerequisites of switching on its AIE. This offers the possibility of switching the emission of TPE by conformation changes.
Die Wiederentdeckung der Wöhlk‐Probe
Authors: Ruppersberg Klaus , Hain Julia 
Published: September 2016

AbstractDie Wöhlk‐Probe ist eine Nachweisreaktion für Lactose und Maltose aus dem Jahre 1904. Sie wurde zunächst klinisch für die Analyse von zuckerhaltigem Urin verwendet. Im Schulunterricht kann sie auf einfache Weise den Lactosegehalt von Milchprodukten zeigen; dies ist insofern interessant, da viele Menschen mit einer Unverträglichkeit auf Milchzucker reagieren. Der genaue Reaktionsmechanismus der Wöhlk‐Reaktion (ähnlich: Umikoff‐Reaktion, Wöhlk‐Malfatti‐Nachweis, Fearon's Test) ist trotz vieler Bemühungen noch unbekannt.
Subject‐loaded quadrifilar helical‐antenna RF coil with high B1+ field uniformity and large FOV for 3‐T MRI
Authors: Athalye Pranav S. , Šekeljić Nada J. , Ilić Milan M. , Tonyushkin Alexey A. , Notaroš Branislav M. 
Published: September 2016

AbstractA novel method for excitation of RF B1 field in high‐field (3‐T) magnetic resonance imaging (MRI) systems using a subject‐loaded quadrifilar helical antenna as an RF coil is proposed, evaluated, and demonstrated. Design, analysis, characterization, and evaluation of the novel coil when situated in a 3‐T MRI bore and loaded with different phantoms are performed and cross‐validated by extensive numerical simulations using multiple computational electromagnetics techniques. The results for the quadrifilar helical‐antenna RF body coil show (a) strong field penetration in the entire phantoms; (b) excellent right‐hand circular polarization (RCP); (c) high spatial uniformity of RCP RF magnetic field, B1+, throughout the phantoms; (d) large field of view (FOV); (e) good transmit efficiency; and (f) low local specific absorption rate (SAR). The examples show that the new RF coil provides substantially better B1+‐field uniformity and much larger FOV than any of the previously reported numerical and experimental results for the existing RF coil designs at 3 T in literature that enable comparison. In addition, helical RF body coils of different lengths can, for instance, easily provide an excellent RCP and highly uniform B1+‐field within the MRI maximum FOV length of 50 cm, and even 100 cm. The proposed MRI RF coil yields a remarkable improvement in the field uniformity in the longitudinal direction, for various phantoms, with comparable efficiency and SAR levels.
A quadrature volume RF coil for vertical B0 field open MRI systems
Authors: Tomanek Boguslaw , Volotovskyy Vyacheslav , Tyson Randy , Yin Donghui , Sharp Jonathan , Blasiak Barbara 
Published: September 2016

AbstractCylindrical quadrature radio frequency (RF) coils are widely used in magnetic resonance imaging and spectroscopy due to their high sensitivity and field uniformity. However, the field geometry is unsuitable for use in low‐field open magnetic resonance imaging (MRI) systems with vertical B0 field configurations. Therefore, a new design is proposed. A quadrature RF coil that combines Alderman‐Grant and Helmholtz designs was constructed to produce two independent modes, both orthogonal to the main magnetic field. The coil provides good RF homogeneity over a 20 × 15 × 15 cm volume and operates as both a transmit and receive coil. The application of the coil for 0.2 Tesla permanent magnet with a vertical B0 field is shown. The proposed coil may be applied to MR imaging of larger objects at low vertical magnetic fields.
Quality of care received and patient‐reported regret in prostate cancer: Analysis of a population‐based prospective cohort
Authors: Holmes Jordan A. , Bensen Jeannette T. , Mohler James L. , Song Lixin , Mishel Merle H. , Chen Ronald C. 
Published: September 2016

BACKGROUNDMeeting quality of care standards in oncology is recognized as important by physicians, professional organizations, and payers. Data from a population‐based cohort of patients with prostate cancer were used to examine whether receipt of care was consistent with published consensus metrics and whether receiving high‐quality care was associated with less patient‐reported treatment decisional regret.METHODSPatients with incident prostate cancer were enrolled in collaboration with the North Carolina Central Cancer Registry, with an oversampling of minority patients. Medical record abstraction was used to determine whether participants received high‐quality care based on 5 standards: 1) discussion of all treatment options; 2) complete workup (prostate‐specific antigen, Gleason grade, and clinical stage); 3) low‐risk participants did not undergo a bone scan; 4) high‐risk participants treated with radiotherapy (RT) received androgen deprivation therapy; and 5) participants treated with RT received conformal or intensity‐modulated RT. Treatment decisional regret was assessed using a validated instrument.RESULTSA total of 804 participants were analyzed. Overall, 66% of African American and 73% of white participants received care that met all standards (P = .03); this racial difference was confirmed by multivariable analysis. Care that included “discussion of all treatment options” was found to be associated with less patient‐reported regret on univariable analysis (P = .03) and multivariable analysis (odds ratio, 0.59; 95% confidence interval, 0.37‐0.95).CONCLUSIONSThe majority of participants received high‐quality care, but racial disparity existed. Participants who discussed all treatment options appeared to have less treatment decisional regret. To the authors' knowledge, this is the first study to demonstrate an association between a quality of care metric and patient‐reported outcome. Cancer 2017;138–143. © 2016 American Cancer Society.
Emergency use of uridine triacetate for the prevention and treatment of life‐threatening 5‐fluorouracil and capecitabine toxicity
Authors: Ma Wen Wee , Saif Muhammad Wasif , El‐Rayes Bassel F. , Fakih Marwan G. , Cartwright Thomas H. , Posey James A. , King Thomas R. , von Borstel Reid W. , Bamat Michael K. 
Published: September 2016

BACKGROUNDIncreased susceptibility to 5‐fluorouracil (5‐FU)/capecitabine can lead to rapidly occurring toxicity caused by impaired clearance, dihydropyrimidine dehydrogenase deficiency, and other genetic variations in the enzymes that metabolize 5‐FU. Life‐threatening 5‐FU overdoses occur because of infusion pump errors, dosage miscalculations, and accidental or suicidal ingestion of capecitabine. Uridine triacetate (Vistogard) was approved in 2015 for adult and pediatric patients who exhibit early‐onset severe or life‐threatening 5‐FU/capecitabine toxicities or present with an overdose. Uridine triacetate delivers high concentrations of uridine, which competes with toxic 5‐FU metabolites.METHODSIn 2 open‐label clinical studies, patients who presented with a 5‐FU/capecitabine overdose or an early onset of severe toxicities were treated. Patients received uridine triacetate as soon as possible (most within the first 96 hours after 5‐FU/capecitabine). Outcomes included survival, resumption of chemotherapy, and safety. Their survival was compared with the survival of a historical cohort of overdose patients who received only supportive care.RESULTSA total of 137 of 142 overdose patients (96%) treated with uridine triacetate survived and had a rapid reversal of severe acute cardiotoxicity and neurotoxicity; in addition, mucositis and leukopenia were prevented, or the patients recovered from them. In the historical cohort, 21 of 25 patients (84%) died. Among the 141 uridine triacetate–treated overdose patients with a diagnosis of cancer (the noncancer patients included 6 intentional or accidental pediatric overdoses), 53 resumed chemotherapy in < 30 days (median time after 5‐FU, 19.6 days), and this indicated a rapid recovery from toxicity. Adverse reactions in patients receiving uridine triacetate included vomiting (8.1%), nausea (4.6%), and diarrhea (3.5%).CONCLUSIONSIn these studies, uridine triacetate was a safe and effective lifesaving antidote for capecitabine and 5‐FU overexposure, and it facilitated the rapid resumption of chemotherapy. Cancer 2017;123:345–356. © 2016 American Cancer Society.
Flexible, Free‐Standing and Holey Graphene Paper for High‐Power Supercapacitors
Authors: Ferrero Guillermo A. , Sevilla Marta , Fuertes Antonio B. 
Published: September 2016

AbstractFlexible supercapacitors based on bendable electrodes have aroused much interest for integration in clothing materials and portable electronic devices. However, simultaneous achievement of high areal energy and high power densities still presents a great challenge. Herein we report the fabrication of free‐standing, flexible graphene papers suitable for high‐performance flexible supercapacitors. The binder‐free graphene paper is made up of two types of holey graphene units (i.e., wrinkled graphene sheets and graphene nanoscrolls) that produce closely interconnected, porous 3D graphene architectures. The graphene papers reported here can be fabricated with a variety of thicknesses and areal densities, in the 10–70 μm and 1–5 mg cm−2 ranges, respectively. They exhibit a remarkable electrochemical performance in aqueous electrolytes: a) a high cell areal capacitance (230–190 mF cm−2 in H2SO4 and 180–170 mF cm−2 in Li2SO4), b) an outstanding capacitance retention of 60 % at ultra‐large current densities of 1200 mA cm−2, c) an excellent long‐term cycling stability and d) high areal power (≈280 mW cm−2) and energy densities (≈32 and ≈60 μWh cm−2 in H2SO4 and Li2SO4, respectively). These highly flexible graphene papers show a great improvement, in terms of areal energy‐power densities, in relation to the state‐of‐the‐art graphene‐based film electrodes.
Nanoparticle‐Templated Molecular Recognition Platforms for Detection of Biological Analytes
Authors: Beyene Abraham G. , Demirer Gozde S. , Landry Markita P. 
Published: September 2016

AbstractMolecular recognition of biological analytes with optical nanosensors provides both spatial and temporal biochemical information. A recently developed sensing platform exploits near‐infrared fluorescent single‐wall carbon nanotubes combined with electrostatically pinned heteropolymers to yield a synthetic molecular recognition technique that is maximally transparent through biological matter. This molecular recognition technique is known as corona phase molecular recognition (CoPhMoRe). In CoPhMoRe, the specificity of a folded polymer toward an analyte does not arise from a pre‐existing polymer‐analyte chemical affinity. Rather, specificity is conferred through conformational changes undergone by a polymer that is pinned to the surface of a nanoparticle in the presence of an analyte and the subsequent modifications in fluorescence readout of the nanoparticles. The protocols in this article describe a novel single‐molecule microscopy tool (near‐infrared fluorescence and total internal reflection fluorescence [nIRF TIRF] hybrid microscope) to visualize the CoPhMoRe recognition process, enabling a better understanding of synthetic molecular recognition. We describe this requisite microscope for simultaneous single‐molecule visualization of optical molecular recognition and signal transduction. We elaborate on the general procedures for synthesizing and identifying single‐walled carbon nanotube‐based sensors that employ CoPhMoRe via two biologically relevant examples of single‐molecule recognition for the hormone estradiol and the neurotransmitter dopamine. © 2016 by John Wiley & Sons, Inc.
A Molecular Ni‐complex Containing Tetrahedral Nickel Selenide Core as Highly Efficient Electrocatalyst for Water Oxidation
Authors: Masud Jahangir , Ioannou Polydoros‐Chrysovalantis , Levesanos Nikolaos , Kyritsis Panayotis , Nath Manashi 
Published: September 2016

AbstractWe report the highly efficient catalytic activity of a transition metal selenide‐based coordination complex, [Ni{(SePiPr2)2N}2], (1) for oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solution. Very low overpotentials of 200 mV and 310 mV were required to achieve 10 mA cm−2 for OER and HER, respectively. The overpotential for OER is one of the lowest that has been reported up to now, making this one of the best OER electrocatalysts. In addition, this molecular complex exhibits an exceptionally high mass activity (111.02 A g−1) and a much higher TOF value (0.26 s−1) at a overpotential of 300 mV. This bifunctional electrocatalyst enables water electrolysis in alkaline solutions at a cell voltage of 1.54 V.