bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Unprecedented Retro‐Mumm Rearrangement Revealed by ESI‐MS/MS, IRMPD Spectroscopy, and DFT Calculations
Authors: Iacobucci Claudio , Reale Samantha , Aschi Massimiliano , Oomens Jos , Berden Giel , De Angelis Francesco 
Published: March 2018

AbstractBrønsted acids and protic solvents mediate acyl transfer, known as the Mumm rearrangement, from imidates to the corresponding acylamides. This represents a key step in several reactions, for example, the Ugi four‐component reaction (U‐4CR) and Passerini three‐component reaction (P‐3CR). Herein, an unprecedented break of the non‐reversibility of the Mumm rearrangement is reported. A combination of electrospray tandem mass spectrometry (ESI‐MS/MS), infrared multiphoton dissociation (IRMPD) ion spectroscopy and theoretical calculations demonstrates the occurrence of the retro‐Mumm rearrangement of protonated isopeptides in the gas phase. In the gas phase, the extra proton acquired during ESI promotes the backward isomerisation reaction in a catalytic fashion.
Solvent and Autocatalytic Effects on the Stabilisation of the σ‐Complex during Electrophilic Aromatic Chlorination
Authors: Van Lommel Ruben , Moors Samuel L. C. , De Proft Frank 
Published: March 2018

AbstractThe solvent and autocatalytic effects of the electrophilic aromatic chlorination of benzene are studied using a combined approach of static calculations and ab initio metadynamics simulations. Different possible reaction pathways are investigated and the influence of the solvents (CCl4, acetonitrile and acetic acid) is thoroughly assessed. Our results show that the stability and lifetime of a charged σ‐complex is increased by electrostatic stabilisation effects of the environment, which can originate from catalytic HCl, solvating effects of polar solvents (acetonitrile), or specific hydrogen bonding interactions with the solvent (acetic acid). Metadynamics simulations reveal a new chlorine addition mechanism explaining the autocatalytic effects of the reaction. The strength of combining static calculations and metadynamics simulations is highlighted, which provide complementary insight into chemical reactions in solvent.
Nickel‐Catalyzed Alkylarylation of Activated Alkenes with Benzyl‐amines via C−N Bond Activation
Authors: Yu Hui , Hu Bin , Huang Hanmin 
Published: March 2018

AbstractA nickel‐catalyzed alkylarylation of active alkenes with tertiary benzylamines was achieved by charge‐transfer‐complex promoted C−N bond activation. The reaction proceeded through initial Ni‐catalyzed C−N bond activation, followed by sequential radical addition, redox and proton abstraction with cleaved amine moiety in the absence of oxidant, and provides an efficient method to prepare various alkyl‐substituted oxindoles and dihydroquinolinones in good yields.
Formal Lossen Rearrangement/[3+2] Annulation Cascade Catalyzed by a Modified Cyclopentadienyl RhIII Complex
Authors: Yamada Takayuki , Shibata Yu , Kawauchi Susumu , Yoshizaki Soichi , Tanaka Ken 
Published: March 2018

AbstractIt has been established that a cyclopentadienyl RhIII complex with two phenyl groups and a pendant amide moiety catalyzes the formal Lossen rearrangement/[3+2] annulation cascade of N‐pivaloyl benzamides and acrylamides with alkynes leading to substituted indoles and pyrroles. Mechanistic studies revealed that this cascade reaction proceeds via not the Lossen rearrangement to form anilides or enamides but C−H bond cleavage, alkyne insertion, and the formal Lossen rearrangement.
Numerical Simulation of Industrial Dry Flue‐Gas Desulfurization Processes
Authors: Klaka Tobias , Kaiser Sven , Barbe Stéphan 
Published: March 2018

AbstractRauchgase aus Kohlekraftwerken enthalten beträchtliche Mengen an Schwefeldioxid, die für die Umwelt dramatische Folgen haben können. Die richtige Auslegung von Entschwefelungsverfahren ist entscheidend und beruht überwiegend auf empirischen Ansätzen. Um die Belastbarkeit und die Zuverlässigkeit des Auslegungsverfahrens zu verbessern, wurde ein Rechenmodel für die trockene Entschwefelung von Rauchgasen mit Partikeln auf Calciumbasis entwickelt. Der detaillierte Aufbau wird beschrieben und die Berechnungsergebnisse mit Prozessdaten aus einem Steinkohlekraftwerk verglichen. Anschließend wurde exemplarisch eine Sensitivitätsanalyse durchgeführt.
Study on Pulse Compression Ultrasonic Imaging by a Stacked M‐Sequence Encoding Probe
Authors: Murata Yorinobu , Kaneda Daiyu 
Published: March 2018

SUMMARYIf an ultrasonic imaging inside an object is possible without scanning by using an ultrasonic probe having a small aperture, the ultrasonic imaging system becomes a simpler and easier system. We have developed a stacked encoding ultrasonic transducer which can transceive an M‐sequence signal only by a pulse drive in order to realize an ultrasonic measurement with a high resolution and high sensitivity. When an ultrasonic probe with such transducer is used, a pulse compression measurement is enabled only with a general ultrasonic flaw detector and a personal computer (PC) without using special devices. In this study, we focused on the characteristic that the received waveform by this probe changes with transceiver directions of a wave. A stacked M‐sequence encoding probe of 7 bits length was manufactured and the one‐dimensional point spread function in transceiver angle was obtained. As a result, it was confirmed that this probe has not only the pulse compression characteristic, but also the angle selecting characteristic. Finally, by using the proposed probe, the cross‐sectional imaging for point objects without scanning was demonstrated.
Ion Transfer Voltammetry in Polyurethane Thin Films Based on Functionalised Cationic [6]Helicenes for Carbonate Detection
Authors: Jarolímová Zdeňka , Bosson Johann , Labrador Geraldine M. , Lacour Jérôme , Bakker Eric 
Published: March 2018

AbstractWe explore here molecular ion‐to‐electron redox probes based on cationic diaza, azaoxa, and dioxa [6]helicenes and their derivatives as ion‐to‐electron transducers for the electrochemical detection of anions. These cationic [6]helicenes exhibit reversible and reproducible oxidation/reduction behavior and facilitate the anion transfer of Gaussian shape into polymeric thin layer sensing films. Films composed of bis(2‐ethylhexyl) sebacate (DOS), polyurethane (PU), tetrakis(4‐chlorophenyl)borate tetradodecylammonium salt (ETH 500) and [6]helicenes were interrogated by cyclic voltammetry. Even though the peak separation of 90 mV is larger than ideal, the observed peak width at half maximum of 130 mV and the linear relationship between current and scan rate are near theoretical values, confirming a surface confined process. A Nernstian shift of the peaks with increasing carbonate concentration is obtained in the presence of carbonate ionophore VII incorporated into the thin sensing film. The concentration of carbonate was determined in an unfiltered sample of the Arve river (flowing from Chamonix to Geneva) and compared to a reference method (automatic titrator with potentiometric detection). The results suggested that cationic diaza [6]helicene functionalized with two bromine atoms is an attractive molecular ion‐to‐electron transducer for anion‐selective electrodes.
Rapid and Flash Tests: Indicator for Quality of HT‐PEM Fuel Cells Batches?
Authors: Rastedt M. , Büsselmann J. , Tullius V. , Wagner P. , Dyck A. 
Published: March 2018

AbstractIn order to control the batch quality of membrane electrode assemblies (MEA), two new short tests have been developed. The first being a rapid test, composed of a start‐up and break‐in followed by initial characterization and has a test duration of about 65 h, while the second is a flash test, which is reduced by the break‐in, so that the maximum duration is 8 h. These tests have been compared with classical accelerated stress tests like load cycling at high current densities and start/stop‐cycling. For the investigations presented in this publication, high temperature polymer electrolyte MEAs from two different suppliers were used. The extensive electrochemical characterization clearly shows that the newly introduced fast tests can be used to check the batch qualities. In addition to the electrochemical investigations, the phosphoric acid content of all MEAs has been determined and ex situ micro‐computed tomography analysis has been performed.
Individual differences in decision making competence revealed by multivariate fMRI
Authors: Talukdar Tanveer , Román Francisco J. , Operskalski Joachim T. , Zwilling Christopher E. , Barbey Aron K. 
Published: March 2018

AbstractWhile an extensive literature in decision neuroscience has elucidated the neurobiological foundations of decision making, prior research has focused primarily on group‐level effects in a sample population. Due to the presence of inherent differences between individuals’ cognitive abilities, it is also important to examine the neural correlates of decision making that explain interindividual variability in cognitive performance. This study therefore investigated how individual differences in decision making competence, as measured by the Adult Decision Making Competence (A‐DMC) battery, are related to functional brain connectivity patterns derived from resting‐state fMRI data in a sample of 304 healthy participants. We examined connectome‐wide associations, identifying regions within frontal, parietal, temporal, and occipital cortex that demonstrated significant associations with decision making competence. We then assessed whether the functional interactions between brain regions sensitive to decision making competence and seven intrinsic connectivity networks (ICNs) were predictive of specific facets of decision making assessed by subtests of the A‐DMC battery. Our findings suggest that individual differences in specific facets of decision making competence are mediated by ICNs that support executive, social, and perceptual processes, and motivate an integrative framework for understanding the neural basis of individual differences in decision making competence.
Anaphylactic reaction to an ultrasound contrast agent (Lumason) in a patient with systemic mastocytosis
Authors: Olson Michael C. , Atwell Thomas D. , Knudsen John M. 
Published: March 2018

AbstractSevere adverse reactions to ultrasound (US) contrast agents are rare, and only a few cases of anaphylaxis following the administration of US contrast agents have been reported, often without a defined etiology. We present a case of anaphylactic reaction to the injection of an US contrast agent in a patient with systemic mastocytosis, which highlights the disorder as a possible risk factor warranting additional consideration prior to performing a contrast‐enhanced US examination.
1H‐MRS for the assessment of renal triglyceride content in humans at 3T: A primer and reproducibility study
Authors: Dekkers Ilona A. , de Heer Paul , Bizino Maurice B. , de Vries Aiko P.J. , Lamb Hildo J. 
Published: March 2018

BackgroundRenal steatosis (fatty kidney) is a potential biomarker for obesity‐related renal disease; however, noninvasive assessment of renal fat content remains a technical challenge.PurposeTo evaluate reproducibility and explore clinical application of renal metabolic imaging for the quantification of renal triglyceride content (TG) using proton magnetic resonance spectroscopy (1H‐MRS).Study typeReproducibility and clinical cohort study.PopulationTwenty‐three healthy volunteers (mean age 30.1 ± 13.4 years) and 15 patients with type 2 diabetes mellitus (T2DM) (mean age 59.3 ± 7.0 years).Field Strength/Sequence3T, single‐voxel point resolved spectroscopy (PRESS).AssessmentIntra‐ and interexamination reproducibility of renal TG was assessed in healthy volunteers, and compared to T2DM patients. Intraexamination differences were obtained by repeating the 1H‐MRS measurement directly after the first 1H‐MRS without repositioning of the subject or changing surface coil and measurement volumes. Interexamination variability was studied by repeating the scan protocol after removal and replacement of the subject in the magnet, and subsequent repositioning of body coil and measurement volumes.Statistical TestsReproducibility was determined using Pearson's correlation and Bland–Altman analyses. Differences in TG% between healthy volunteers and T2DM patients were assessed using the Mann–Whitney U‐test.ResultsAfter logarithmic (log) transformation, both intraexamination (r = 0.91, n = 19) and interexamination (r = 0.73, n = 9) measurements of renal TG content were highly correlated with the first renal TG measurements. Intraexamination and interexamination limits of agreement of renal log TG% were respectively [−1.36%, + 0.84%] and [−0.77%, + 0.62%]. Backtransformed limits of agreement were [−0.89%,+0.57%] and [−0.55%, + 0.43%] multiplied by mean TG for intra‐ and interexamination measurements. Overall median renal TG content was 0.12% [0.08, 0.22; 25th percentile, 75th percentile] in healthy volunteers and 0.20% [0.13, 0.22] in T2DM patients (P = 0.08).Data ConclusionRenal metabolic imaging using 3T 1H‐MRS is a reproducible technique for the assessment of renal triglyceride content.Level of Evidence: 3Technical Efficacy: Stage 1J. MAGN. RESON. IMAGING 2018;48:507–513.
Synthesis and Properties of Quaternary Ammonium Surfactants Based on Alkylamine, Propylene Oxide, and 2‐Chloroethanol
Authors: Asadov Ziyafaddin H. , Ahmadova Gulnara A. , Rahimov Ravan A. , Abilova Aygul Z. , Zargarova Sevda H. , Zubkov Fedor I. 
Published: March 2018

AbstractNew quaternary ammonium salts are synthesized by octylamine, nonylamine, dodecylamine, and hexadecylamine reacting with propylene oxide at a mole ratio of 1:2, followed by reaction with 2‐chloroethanol. By tensiometric measurements of aqueous solutions, their surface activity has been determined. Using the results of these measurements and electroconductometric studies, important parameters such as critical micelle concentration (CMC), efficiency of surfactant adsorption, surface pressure at the CMC, changes of Gibbs free energies for micelle formation, and adsorption were estimated. By application of the Gibbs adsorption isotherm, indices such as maximum surface excess concentration and minimum surface area/molecule at the air–water interface were also calculated. Petroleum‐collecting properties of these surfactants were investigated. Among these quaternary ammonium surfactants, the surfactant based on dodecylamine, propylene oxide, and 2‐chloroethanol exhibits the highest petroleum‐collecting capacity.
Effects of microwave‐assisted pulse‐spouted bed freeze‐drying (MPSFD) on volatile compounds and structural aspects of Cordyceps militaris
Authors: Wu Xiao‐fei , Zhang Min , Bhandari Bhesh , Li Zhongqin 
Published: March 2018

AbstractBACKGROUNDMicrowave‐assisted pulse‐spouted bed freeze‐drying (MPSFD) uses microwave heating to substitute the customary conduction heating during freeze drying (FD), resulting in high‐quality dried samples with a short drying time. The aim of this study was to determine the effect of MPSFD on volatile compounds and structural aspects of Cordyceps militaris. In order to highlight the effect of MPSFD, FD (recognized for its high‐quality products) and hot‐air dying (HD; the most commonly used) were also evaluated using headspace solid‐phase micro‐extraction combined with gas chromatography–mass spectrometry and mid‐Fourier transform infrared spectroscopy.RESULTSSixty‐two components were obtained by FD, 62 compounds by MPSFD and 39 by HD. FD and MPSFD exhibited much better effects on the retention of volatile components of C. militaris than HD. Principal component analysis, hierarchical clustering analysis and E‐nose analysis indicated that the volatile compounds of C. militaris dried by FD and MPSFD were similar. The spectral features of FD and MPSFD samples were also similar, whereas the HD sample presented a clearly different spectral feature around a wavenumber of 1640 cm−1.CONCLUSIONMPSFD exhibited a beneficial effect on aroma and structure retention, with shorter drying time and lower energy consumption. © 2018 Society of Chemical Industry
Duck nest depredation, predator behavior, and female response using video
Authors: Croston Rebecca , Ackerman Joshua T. , Herzog Mark P. , Kohl Jeffrey D. , Hartman C. Alex , Peterson Sarah H. , Overton Cory T. , Feldheim Cliff L. , Casazza Michael L. 
Published: March 2018

ABSTRACTDepredation plays an important role in determining duck nest success and predator and female duck behavior during nest depredation can influence nest fate. We examined depredation of mallard (Anas platyrhynchos) and gadwall (A. strepera) nests in Suisun Marsh, California, USA, in 2015–2016 with continuous infrared video monitoring to identify nest predators and characterize predator and female duck behavior during depredation events. We recorded predators at 44% of 147 nests monitored. Raccoons (Procyon lotor) were the most frequent predator observed at nests (40% of nests visited and 53% of depredated eggs) followed by striped skunks (Mephitis mephitis; 27% and 27%), coyotes (Canis latrans; 4% and 9%), common ravens (Corvus corax; 4% and 9%), gopher snakes (Pituophis catenifer catenifer; 19% and 0%), and western yellow‐bellied racers (Coluber constrictor mormon; 1% and 0%). The number of eggs depredated per depredation bout varied among predators (raccoons: 7.3 eggs; skunks: 2.5; coyotes: 7.4; ravens: 7.7; and snakes: 0.0). Mammal depredation occurred between 1600 and 0400, whereas snakes and ravens were observed at nests during the day (snakes: 1000–2100; ravens: 1700). Females flushed from nests immediately before predator arrival ( = 29.0 ± 16.6 [SD] sec), and this timing did not vary among predators. However, the length of nest depredation bouts varied among predators. Nest visits by gopher snakes were longer (18.6 ± 19.4 min) than depredation bouts by other predators (12.3 ± 10.7 min), but snakes did not successfully consume any eggs. Females took more time to return to nests when nests were depredated by raccoons (239 ± 137 min), whereas females returned more quickly when nests were visited by skunks (81 ± 163 min) or gopher snakes (15 ± 128 min). Partial clutch depredation occurred at 15% of depredated nests, but only 23% of partially depredated nests successfully hatched ≥1 egg. Our results indicate that predator type and behavior can influence female behavior and nest fate, and that management actions that reduce the effectiveness of raccoons and skunks encountering waterfowl nests may benefit these nesting populations. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
Double‐clad fiber Michelson interferometer for measurement of temperature and refractive index
Authors: Musa S. M. A. , Baharin N. F. , Azmi Asrul Izam , Ibrahim R. K. Raja , Abdullah A. S. , Mohd Noor M. Y. , Qi Haifeng 
Published: March 2018

AbstractAn all‐fiber Michelson interferometer based on double‐clad fiber (DCF) is proposed for temperature and refractive index (RI) sensing. The sensor is formed by continuous splicing between single mode fiber, multimode fiber, and DCF. Temperature measurement is achieved by monitoring the dip wavelength shift of the interferometer spectra resulting from thermo‐optic effect on core and first cladding of DCF. RI measurement is established from the power change in spectra due to the Fresnel's reflection at the DCF tip. Experimental result on 18.5 mm sensor manifests that temperature and RI responses are distinguishable. For instance, power level at 1540.5 nm exhibits quadratic shift to RI changes while unaffected to temperature changes. Dip wavelengths of sensor spectra demonstrate linear shift to temperature changes while unaffected by RI changes. The proposed sensor is cost effective as sensor fabrication only requires conventional splicing. Sensor capability to distinguish temperature and RI parameters makes it practical for broad range applications including for biomedical and food industries.
A fully tunable two‐pole bandpass filter with wide tuning range based on half mode substrate integrated waveguide
Authors: Lan Bozhang , Guo Chenjiang , Ding Jun 
Published: March 2018

AbstractA two‐pole tunable bandpass filter (BPF) which allows for the operational agility of both center frequency and bandwidth is proposed in this article. The fundamental structure is based on half mode substrate integrated waveguide (HMSIW) with different dimensions. Two sets of varactors placed at various nodes separately are utilized for adjusting center frequency and bandwidth over a wide tuning range. By adding a source‐load coupling path, two transmission zeros are produced on both sides of the passband to improve filter selectivity significantly. A second‐order 1.52–2.76 GHz filter with 3 dB constant bandwidth tuning from 240 to 350 MHz is developed, analyzed, simulated, and fabricated. Good agreement is obtained between simulated and experimental results.
A novel illumination‐efficient dimming control scheme based on reversed unipolar return‐to‐zero coding and circular (7, 1) modulation in high‐speed visible light communication
Authors: Zhao Jiaqi , Chi Nan 
Published: March 2018

AbstractVisible light communication (VLC) is an emerging optical wireless communication, which combines lighting and communication simultaneously. In indoor VLC systems, the brightness of LEDs should be dimmed to a certain level to support the illumination function. In this article, we propose a novel dimming control scheme based on Reversed Unipolar Return‐to‐Zero (RURZ) coding and circular (7, 1) modulation. The dimming level is determined by the duty cycle ratio (DCR) of the RURZ codes. Contrary to traditional RZ coding, with the decrease of DCR, the component of high‐level signal in RURZ codes increases and could constantly keep LEDs on. Therefore, when the DCR is smaller, the time that the LED is on keeps longer and the illumination efficiency is higher. A special shaped 8‐QAM modulation scheme called circular (7, 1) is employed to obtain a wider dimming range and higher communication quality for its superiority in operation range and bit error ratio (BER) performance. Furthermore, pulse shaping technology is utilized to suppress the wide spectrum extended by RURZ coding and increase the spectral efficiency (SE) and the data rate. Theoretical analysis and experimental investigation demonstrate that the RURZ coded and circular (7, 1) modulated VLC system could achieve a wide dimming range with high illumination efficiency and high communication speed. An illumination efficiency improvement of 0.63 is successfully achieved at 30% DCR with a data rate of 1.35 GB/s over 1 m free space transmission.
Low‐frequency detection of acoustic signals using fiber as an ultrasonic guide with a distant in‐fiber Bragg grating
Authors: Leal Wescley A. , Carneiro Mateus B. R. , Freitas Taiane A. M. G. , Marcondes Cláudia B. , Ribeiro Ricardo M. 
Published: March 2018

AbstractThis article shows the development of a photonic detector of low‐frequency ultrasonic signals. These signals latter reach a sensitive single‐mode optical fiber as an acoustic guide conveying the signals (around 43 kHz) over 70 cm to a distant and protected in‐fiber Bragg grating. The grating reflects a spectrum centered around 1550 and 2.6 nm bandwidth and is interrogated by a tunable laser in their linear and most sensitive region. As a result, real‐time passive demodulation of communication or monitoring of ultrasonic signals propagating through solid materials is possible. The detector may also be applied to other physical media. In this study, a new passive technique to thermally desensitize the fiber‐Bragg gratings (FBG) is also proposed, though the proposed technique is not experimentally tested.