bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a Borylborylene
Authors: Stennett Tom E. , Mattock James D. , Vollert Ivonne , Vargas Alfredo , Braunschweig Holger 
Published: February 2018

AbstractCyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared through boron–silicon exchange between arylsilanes and B2Br4. Coordination of Lewis bases to the remaining sp2 boron atom yielded unsymmetrical sp3‐sp3 diboranes, which were reduced with KC8 to their corresponding trans‐diborenes. These compounds were studied with a combination of spectroscopic methods, X‐ray diffraction, and DFT calculations. PMe3‐stabilized diborene 6 was found to undergo thermal rearrangement to gem‐diborene 8. DFT calculations on 8 reveal a polar boron–boron bond, and indicate that the compound is best described as a borylborylene.
Sigmatropic Rearrangements of Hypervalent‐Iodine‐Tethered Intermediates for the Synthesis of Biaryls
Authors: Hori Mitsuki , Guo Jing‐Dong , Yanagi Tomoyuki , Nogi Keisuke , Sasamori Takahiro , Yorimitsu Hideki 
Published: February 2018

AbstractMetal‐free dehydrogenative couplings of aryliodanes with phenols to afford 2‐hydroxy‐2′‐iodobiaryls have been developed. This reaction proceeds through ligand exchange on the hypervalent iodine atom followed by a [3,3] sigmatropic rearrangement and with complete regioselectivity. This coupling, in combination with in situ oxidation by mCPBA, enables the convenient conversion of iodoarenes into desirable biaryls. The obtained biaryls have convertible iodo and hydroxy groups in close proximity, and are thus synthetically useful, as exemplified by the controlled syntheses of π‐extended furans and a substituted [5]helicene. DFT calculations clearly revealed that the rearrangement is sigmatropic, with C−C bond formation and I−O bond cleavage proceeding in a concerted manner. Acetic acid, which was found to be the best solvent for this protocol, renders the iodine atom more cationic and thus accelerates the sigmatropic rearrangement.
Verification of a physiologically based pharmacokinetic model of ritonavir to estimate drug–drug interaction potential of CYP3A4 substrates
Authors: Umehara Ken‐ichi , Huth Felix , Won Christina S. , Heimbach Tycho , He Handan 
Published: February 2018

AbstractRitonavir is one of several ketoconazole alternatives used to evaluate strong CYP3A4 inhibition potential in clinical drug–drug interaction (DDI) studies. In this study, four physiologically based pharmacokinetic (PBPK) models of ritonavir as an in vivo time‐dependent inhibitor of CYP3A4 were created and verified for oral doses of 20, 50, 100 and 200 mg using the fraction absorbed (Fa) and oral clearance (CLoral) values reported in the literature, because transporter and CYP enzyme reaction phenotyping data were not available. The models were used subsequently to predict and compare the magnitude of the AUC increase in nine reference DDI studies evaluating the effect of ritonavir at steady‐state on midazolam (CYP3A4 substrate) exposure. Midazolam AUC and Cmax ratios were predicted within 2‐fold of the respective observations in seven studies. Simulations of the hepatic and gut CYP3A4 abundance after multiple oral dosing of ritonavir indicated that a 3‐day treatment with ritonavir 100 mg twice daily is sufficient to reach maximal CYP3A4 inhibition and subsequent systemic exposure increase of a CYP3A4 substrate, resulting in the reliable estimation of fm,CYP3A4. The ritonavir model was submitted as part of the new drug application for Kisqali® (ribociclib) and accepted by health authorities.
Fadenwürmer – fade Würmer?
Authors: Hohberg Karin , Traunspurger Walter 
Published: February 2018

ZusammenfassungNematoden spielen nicht nur als Parasiten in Mensch, Tier und Pflanze eine – wenn auch negative – so doch herausragende Rolle. Sie wirken vor allem als ausgesprochene Nützlinge für uns: Sie sind als wichtiger, natürlicher Bestandteil des Nahrungsnetzes maßgeblich und unverzichtbar am Nährstoffkreislauf beteiligt. Außerdem setzen wir sie in zunehmendem Maße gewinnbringend in der biologischen Schädlingsbekämpfung, der ökotoxikologischen Bewertung von Böden und Sedimenten und als ausgezeichnete Modellorganismen für die Forschung ein.
Der Zellkern – eine Stadt in der Zelle, Teil 2
Authors: Cremer Christoph , Szczurek Aleksander , Strickfaden Hilmar , Birk Udo , Cremer Marion , Cremer Thomas 
Published: February 2018

ZusammenfassungIm zweiten Teil des Beitrags zur Zellkernarchitektur beschreiben wir die bahnbrechenden Möglichkeiten der superauflösenden Fluoreszenzmikroskopie (Nanoskopie) und neuer molekularbiologischer Verfahren zur Erforschung der Struktur von Chromatindomänen im Nanometer‐Maßstab und ihrer räumlichen Anordnung zu größeren Aggregaten. Neue experimentelle Daten und Modelle sprechen für eine entscheidende Rolle dieser Strukturen für die Genregulation und andere Funktionen des Zellkerns.
Die Mundhöhle als Ökosystem
Authors: Meyer Frederic , Enax Joachim 
Published: February 2018

ZusammenfassungZahn‐ und Zahnfleischerkrankungen sind weit verbreitet und basieren primär auf der Anwesenheit bakterieller Biofilme. Die Charakterisierung von Biofilmen kann durch modernste Mikrobiomanalysen erfolgen, die Informationen über Bakterienzusammensetzung und ‐Diversität liefern können.Moderne Zahnpflegepräparate enthalten unterschiedliche antimikrobielle Wirkstoffe zur Biofilmkontrolle. Hierzu zählen Chlorhexidin, Metallsalze und quartäre Ammoniumverbindungen, die allerdings häufig schädliche (Dysbiose auslösende) wie nützliche (Homöostase aufrechterhaltende) Bakterien abtöten (unspezifische antimikrobielle Wirkung). Aktuelle Entwicklungen zeigen, dass innovative Konzepte das ökologische Gleichgewicht der Plaque in der Mundhöhle zugunsten der „physiologischen kommensalen Bakterien” (Homöostase) verschieben oder die bakterielle Kolonisation an den Zahnschmelz minimieren, ohne ausgeprägte antimikrobielle Eigenschaften aufweisen. Beispiele sind biomimetische Ansätze, zum Beispiel auf Basis ausgewählter Speichelenzyme oder Hydroxylapatit.
Salvisertin A, a New Hexacyclic Triterpenoid, and Other Bioactive Terpenes from Salvia deserta Root
Authors: Wang Yin‐Ru , Yu Yun , Li Shu‐Ming , Liu Wei , Li Wei , Morris‐Natschke Susan L. , Goto Masuo , Lee Kuo‐Hsiung , Huang Xue‐Feng 
Published: February 2018

Using various chromatographic methods, a new hexacyclic triterpenoid, 2β,3β,24β‐trihydroxy‐12,13‐cyclotaraxer‐l4‐en‐28oic acid (1), together with ten known compounds, 2α,3α,23‐trihydroxyurs‐12,20(30)‐dien‐28oic acid (2), 6,7‐dehydroroyleanone (3), horminone (4), 7‐O‐methylhorminone (5), sugiol (6), demethylcryptojaponol (7), 14‐deoxycoleon U (8), 5,6‐didehydro‐7‐hydroxy‐taxodone (9), ferruginol (10), and dichroanone (11), were isolated from the roots of Salvia deserta. Their structures were identified on the basis of spectroscopic analysis and comparison with the reported data. The individual compounds (1, 3 – 8) were screened for cytotoxic activity, using the sulforhodamine B bioassay (SRB) method. As the results, Compounds 3, 5, and 8 showed cytotoxic potency against A549, MDA‐MB‐231, KB, KB‐VIN, and MCF7 cell lines with IC50 values ranging from 6.5 to 10.2 μm.
Frontline brentuximab vedotin in breast implant‐associated anaplastic large‐cell lymphoma
Authors: Alderuccio Juan Pablo , Desai Amrita , Yepes Monica M. , Chapman Jennifer R. , Vega Francisco , Lossos Izidore S. 
Published: February 2018

Key Clinical MessageWe report a woman who developed BIA‐ALCL 9 years after saline implant placement. The lymphoma manifested as a mass lesion associated with axillary lymphadenopathy. She was successfully treated with brentuximab vedotin with minimal toxicity. Brentuximab vedotin may be a promising frontline therapeutic modality for patients with BIA‐ALCL.
Design and Optimization of Fibrous Filter Media Using Lifetime Multipass Simulations
Authors: Azimian Mehdi , Kühnle Christopher , Wiegmann Andreas 
Published: February 2018

AbstractThe goal of this study was to optimize fibrous filter media by increasing the dust holding capacity (DHC) while maintaining the β ratio and initial pressure drop of the filter media. The key was the use of microstructure models to optimize the filter media. The microstructure of three different variations of a filter media for oil filtration was modeled by using the FiberGeo module of the GeoDict® software package. It was found that by optimizing the fiber volume distribution over the height of the filter media, higher DHC values could be achieved while keeping the pressure drop considerably low. This confirms the hypothesis that the macroscopic properties of the filter element can be improved by modifying the microstructure of the filter media.
Purine‐Derived Nitroxides for Noncovalent Spin‐Labeling of Abasic Sites in Duplex Nucleic Acids
Authors: Kamble Nilesh R. , Sigurdsson Snorri Th. 
Published: February 2018

AbstractA series of purine‐based spin labels was prepared for noncovalent spin‐labeling of abasic sites of duplex nucleic acids through hydrogen bonding to an orphan base on the opposing strand and π‐stacking interactions with the flanking bases. Both 1,1,3,3‐tetramethylisoindolin‐2‐yloxyl and 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) were conjugated to either the C2‐ or C6‐position of the purines, yielding nitroxide derivatives of guanine, adenine, or 2,6‐diaminopurine. The isoindoline‐derived spin labels showed extensive or full binding to abasic sites in RNA duplexes, whereas the TEMPO‐derived spin labels showed limited binding. An adenine‐derived spin label (5) bound fully at low temperature to abasic sites in both DNA and RNA duplexes when paired with thymine and uracil, respectively, complementing the previously described guanine‐derived spin label Ǵ, which binds efficiently opposite cytosine. Compound Ǵ was also shown to bind to abasic sites in DNA–RNA hybrids, either in the DNA‐ or the RNA‐strand. Ǵ showed only a minor flanking‐sequence effect upon binding to abasic sites in RNA. When the abasic site was placed close to the end of the RNA duplex, the affinity of the spin label Ǵ was reduced; full binding was observed at the fourth position from the duplex end. In summary, spin labels 5 and Ǵ showed full binding to abasic sites in both DNA and RNA duplexes and are promising spin labels for structural studies of nucleic acids by pulsed EPR methods.
Electronically Unsaturated Three‐Coordinate Aluminum Hydride and Organoaluminum Cations
Authors: Prashanth Billa , Bhandari Mamta , Ravi Satyam , Shamasundar K. R. , Singh Sanjay 
Published: February 2018

AbstractNew three‐coordinate and electronically unsaturated aluminum hydride [LAlH]+[HB(C6F5)3]− (LH=[{(2,6‐iPr2C6H3N)P(Ph2)}2N]H) and aluminum methyl [LAlMe]+[MeB(C6F5)3]− cations have been prepared. The quantitative estimation of Lewis acidity by Gutmann–Beckett method revealed [LAlH]+[HB(C6F5)3]− to be better Lewis acid than B(C6F5)3 and AlCl3 making these compounds ideal catalysts for Lewis acid‐mediated reactions. To highlight that the work is of fundamental importance, catalytic hydroboration of aliphatic and aromatic aldehydes and ketones have been demonstrated. Important steps of the catalytic cycle have been probed by using multinuclear NMR measurements, including successful characterization of the proposed aluminum benzyloxide cationic intermediate, [LAl‐O‐CH2Ph]+[HB(C6F5)3]−. The proposed catalytic cycle has been found to be consistent with experimental observations and computational studies clearly indicating the migration of hydride from cationic aluminum center to the carbonyl carbon is the rate‐limiting step of the catalytic cycle.
Impact of Zeolite Structure on Entropic–Enthalpic Contributions to Alkane Monomolecular Cracking: An IR Operando Study
Authors: Kadam Shashikant A. , Li Haoguang , Wormsbecher Richard F. , Travert Arnaud 
Published: February 2018

AbstractThe monomolecular cracking rates of propane and n‐butane over MFI, CHA, FER and TON zeolites were determined simultaneously with the coverage of active sites at reaction condition using IR operando spectroscopy. This allowed direct determination of adsorption thermodynamics and intrinsic rate parameters. The results show that the zeolite confinement mediates enthalpy–entropy trade‐offs only at the adsorbed state, leaving the true activation energy insensitive to the zeolite or alkane structure while the activation entropy was found to increase with the confinement. Hence, relative cracking rates of alkanes within zeolite pores are mostly governed by activation entropy.
Polarization in France
Authors: Kahr Bart 
Published: February 2018

AbstractThe special relationship between France and the polarization of light from the beginning of the 19th century until the present day is reviewed in the lives and works of Étienne Louis Malus, François Arago, Jean‐Baptiste Biot, Augustin Fresnel, Louis Pasteur, Frédéric Wallerant, Aimé Cotton, Francis Perrin, and Alain Aspect. To avoid a redundant presentation of information that can be found with an Internet search engine, the author emphasizes how the aforementioned individuals have influenced the studies of stereochemistry, molecular chirality, and the polarization of light in his research group.
Analysis of stereoisomers of chiral drug by mass spectrometry
Authors: Chen Xiaolei , Kang Yu , Zeng Su 
Published: February 2018

AbstractChiral molecules are of great importance in the life science since individual enantiomers may differ in biological activity, mechanism, and toxicity, making it necessary to explore efficient chiral analysis methods. Chromatography approaches are often used to differentiate enantiomers while mass spectrometry (MS) was thought to be blind in chiral analysis. With the development of MS technique, it began to play a more and more crucial part in chiral observation. In this review, we will give a detailed introduction of the analysis methods related to MS for chiral drugs, including its mechanism, applications, and future development.
New Analysis Method for Interground Cements
Authors: Unseld Johannes , Wolter Albrecht 
Published: February 2018

AbstractErstmals können Zemente mit mehreren Hauptbestandteilen, die durch gemeinsame Vermahlung entstanden sind hinsichtlich ihrer inneren Kornverteilung analysiert und beurteilt werden. Zu diesem Zweck wurden zwei Verfahren entwickelt, um sowohl den laufenden Betrieb mittels Werksmethode als auch die Produktanforderungen mithilfe weiterer unabhängiger Labormethode zu analysieren. Für die Werksmethode ist eine Kombination aus Sichter und XRD‐Rietveld vorgesehen, während als Labormethode ein nasschemischer Trennungsgang kombiniert mit der Lasergranulometrie eingesetzt wird.
ROLE OF SNOW DEPTH IN THE INFLUENCE OF EL NIÑO ON SUMMER CLIMATE ANOMALIES OVER EAST ASIA
Authors: Yan‐Feng WANG , Xu‐Guang SUN , Xiu‐Qun YANG 
Published: February 2018

AbstractWith the datasets of Global Land Data Assimilation System (GLDAS) NOAH land surface model, GPCC monthly mean rainfall, and NCAR/NCEP global monthly mean reanalysis from 1948 to 2010, by using methods of filtering, composite and linear regression and correlation, the characteristics of Eurasian snow depth anomalies in El Niño mature winter, its influences on soil moisture after snow melting, and finally on East Asian summer monsoon are investigated, and the main conclusions are as follows: In El Niño mature winter, snow depth in regions of the Iranian Plateau, the northeast of Lake Balkhash and the southern Tibetan Plateau increases remarkably, so are the related snow melting and soil moisture. The above‐mentioned three regions are identified as the key regions for snow depth to store and extend the El Niño signals. In spring, the snow begins to melt, and the soil moisture increases correspondingly, thus the El Niño signals are transmitted from winter snow depth to soil moisture in spring. As a result, sensible heat flux decreases and latent heat flux increases, and the atmospheric circulations are greatly influenced. The anomalous soil moisture in the Iranian plateau is most important for the East Asian summer monsoon in El Niño decaying summer, since it has similar impact pattern on the anomalous summer precipitation as the El Niño composite. The spring and summer soil moisture in both the southern Tibetan plateau and the northeast of Lake Balkhash increase simultaneously, which significantly contribute to the increased precipitation in North China. Therefore, to investigate and predict the East Asian summer monsoon variability by using El Niño signal, the roles of snow depth in storing and modulating El Niño impacts in those key regions should be considered.
SURFACE DEFORMATION AND EARLY WARNING MAGNITUDE OF 2016 KAIKOURA (NEW ZEALAND) EARTHQUAKE FROM HIGH‐RATE GPS OBSERVATIONS
Authors: Chuang SONG , Cai‐Jun XU , Yang‐Mao WEN , Lei YI , Wen XU 
Published: February 2018

AbstractOn 13th November 2016, the Kaikoura region of New Zealand was struck by a major Mw7.8 earthquake. In this study, coseismic deformation field is derived from 1 Hz high‐rate GPS observations based on the GAMIT track solution module, combining with PCA spatial filtering method firstly. Then the 5 s peak displacement of P‐wave (Pd) and the peak ground displacement (PGD) are extracted from the real‐time simulated kinematic displacements of the trackRTr module. Finally, the warning magnitude is calculated from the statistical regression model. Our results indicate that the duration time of the kinematic deformation is up to 2 min. The KAIK and HANM stations, which are closest to the epicenter, have secondary severe deformation. And the deformation amplitude of the north stations of the epicenter is larger than that of the south. The static coseismic deformation field from high‐rate GPS observations shows the characteristics of the focal mechanism of strike‐slip after thrust. In addition, the Pd warning magnitudes from different stations have a significant difference, with the maximum magnitude difference of Mw2.5. Considering the timeliness and reliability of the warning magnitude jointly, the warning magnitude from the four‐station PGD joint warning method of reasonable spatial distribution can reach its initial stability (Mw7.56) at 23 s after the event, while final stability (Mw7.78) at 110 s, which is consistent with the USGS moment tensor magnitude (Mw7.8).
AUTOMATIC ESTIMATION OF STACKING VELOCITY BASED ON SPARSE INVERSION
Authors: Wen‐Jun XU , Jun‐Feng YIN , Hua‐Zhong WANG , Bo FENG 
Published: February 2018

AbstractStacking velocity analysis is a routine procedure in seismic data processing, and is also a classical method for initial velocity model building. Usually, stacking velocity analysis is divided into two steps: calculating stacking velocity spectra and picking spectra maximums. Until now, many researchers are trying to improve the stacking velocity spectra by computing a better semblance, considering the AVO effect or improving the anti‐noise ability of algorithm. However, it is seldom discussed on how to calculate the stacking velocity automatically. In this paper, we try to solve this problem by combining the velocity spectra calculation and picking procedure into a model parameter estimation under the framework of sparse inversion. Therefore, it is possible to invert the stacking velocity automatically and shorten the turn‐around time of initial velocity model building and reduce human costs considerably. To solve this problem, first we give the definition of forward problem, which is the prediction model for CMP gather using stacking velocity and t0 time as model parameters. Then, the inverse problem is defined as finding the sparse model parameters with the given CMP gather. Using the sparsity of model parameters as model constraint, we reformulate the conventional stacking velocity analysis problem as a new sparse inverse problem, and present an adaptive matching pursuit (MP) algorithm to solve it. The proposed method is quite promising for automatic initial model building, and can provide a good initial model for subsequent high‐resolution velocity inversion methods. Numerical and field data tests demonstrate the effectiveness of the proposed method.
PREDICTION OF THE METHANE SUPPLY AND FORMATION PROCESS OF GAS HYDRATE RESERVOIR AT ODP1247, HYDRATE RIDGE, OFFSHORE OREGON
Authors: Zi‐Han ZHENG , Yun‐Cheng CAO , Duo‐Fu CHEN 
Published: February 2018

AbstractThe formation of gas hydrate reservoir in marine sediments is mainly controlled by methane supply and sedimentary burial. Based on the mass conservation of methane in gas hydrate system, a numerical model of gas hydrate formation was established considering the methane supplied by dissolved methane diffusion, pore water advection, and in situ methanogenesis. A case study of ODP site 1247 at the Hydrate Ridge, offshore Oregon shows that dissolved methane transported by molecular diffusion and pore water advection is the major supply of methane for gas hydrate formation, while in situ methanogenesis contributes little to the gas hydrate reservoir. The gas hydrate reservoir was also evaluated considering the changes of sedimentation rate since 1.67 Ma. Our model results show that the variations of sedimentation rate lead to little change in the size of gas hydrate reservoir at ODP 1247. The calculated hydrate saturation amounts to ∼0%∼3%, which is consistent with the measured values using pressure coring.
TIME‐DAMPING FULL WAVEFORM INVERSION OF MULTI‐DOMINANT‐FREQUENCY WAVEFIELDS
Authors: Sheng‐Chang CHEN , Guo‐Xin CHEN 
Published: February 2018

AbstractThe lack of low‐frequency components and the subsurface strong variations of velocity can lead to severe cycle‐skipping phenomenon, which is a big challenge to full waveform inversion of seismic data. Through the applications of the time‐damping and the time integration for decreasing the dominant‐frequency of seismic wavefield, a time‐damping full waveform inversion of multi‐dominant‐frequency wavefields is proposed. This method can efficiently eliminate the cycle‐skipping phenomenon. Velocity errors from shallow to deep can lead to misfits of travel‐time and their accumulations. The accurate inversion of shallow velocity can efficiently reduce the misfits of travel‐time and cycle‐skipping phenomenon in the inversion of later waveform. Applying the time‐damping approach to seismic data can obtain time‐damped data. The inversion of these time‐damped data with different damping values can produce the results from shallow to deep depth. The cycle‐skipping phenomenon is weak for the wavefields with lower dominant‐frequency compared to higher dominant‐frequency wavefields. The time integration of different orders of the seismic wavefield can produce wavefields with different dominant frequencies. The inversion results of low dominant‐frequency wavefields are used as the starting models for the full waveform inversion of high dominant‐frequency wavefields. Numerical tests using synthetic data lacking low‐frequency components below 4Hz of the 2D salt‐dome model have demonstrated the validity and feasibility of the proposed method. The final results show that the time‐damping full waveform inversion of multi‐dominant‐frequency wavefields has proper flexibility for seismic data lacking low‐frequency components and in case of strong subsurface velocity variations.