bluuebunny/crossref_metadata_2025 huggingface dataset:
The Digital Fields Board for the FIELDS instrument suite on the Solar Probe Plus mission: Analog and digital signal processing
Authors: Malaspina David M. , Ergun Robert E. , Bolton Mary , Kien Mark , Summers David , Stevens Ken , Yehle Alan , Karlsson Magnus , Hoxie Vaughn C. , Bale Stuart D. , Goetz Keith
Published: May 2016

The first in situ measurements of electric and magnetic fields in the near‐Sun environment (< 0.25 AU from the Sun) will be made by the FIELDS instrument suite on the Solar Probe Plus mission. The Digital Fields Board (DFB) is an electronics board within FIELDS that performs analog and digital signal processing, as well as digitization, for signals between DC and 60 kHz from five voltage sensors and four search coil magnetometer channels. These nine input signals are processed on the DFB into 26 analog data streams. A specialized application‐specific integrated circuit performs analog to digital conversion on all 26 analog channels simultaneously. The DFB then processes the digital data using a field programmable gate array (FPGA), generating a variety of data products, including digitally filtered continuous waveforms, high‐rate burst capture waveforms, power spectra, cross spectra, band‐pass filter data, and several ancillary products. While the data products are optimized for encounter‐based mission operations, they are also highly configurable, a key design aspect for a mission of exploration. This paper describes the analog and digital signal processing used to ensure that the DFB produces high‐quality science data, using minimal resources, in the challenging near‐Sun environment.
Normal faulting in the Simav graben of western Turkey reassessed with calibrated earthquake relocations
Authors: Karasözen Ezgi , Nissen Edwin , Bergman Eric A. , Johnson Kendra L. , Walters Richard J.
Published: May 2016

Western Turkey has a long history of large earthquakes, but the responsible faults are poorly characterized. Here we reassess the past half century of instrumental earthquakes in the Simav‐Gediz region, starting with the 19 May 2011 Simav earthquake (Mw 5.9), which we image using interferometric synthetic aperture radar and regional and teleseismic waveforms. This event ruptured a steep, planar normal fault centered at 7–9 km depth but failed to break the surface. However, relocated main shock and aftershock hypocenters occurred beneath the main slip plane at 10–22 km depth, implying rupture initiation in areas of low coseismic slip. These calibrated modern earthquakes provide the impetus to relocate and reassess older instrumental events in the region. Aftershocks of the 1970 Gediz earthquake (Mw 7.1) form a narrow band, inconsistent with source models that invoke low‐angle detachment faulting, and may include events triggered dynamically by the unilateral main shock rupture. Epicenters of the 1969 Demirci earthquakes (Mw 5.9, 6.0) are more consistent with slip on the south dipping Akdağ fault than the larger, north dipping Simav fault. A counterintuitive aspect of recent seismicity across our study area is that the largest event (Mw 7.1) occurred in an area of slower extension and indistinct surface faulting, yet ruptured the surface, while recent earthquakes in the well‐defined and more rapidly extending Simav graben are smaller (Mw <6.0) and failed to produce surface breaks. Though our study area bounds a major metamorphic core complex, there is no evidence for involvement of low‐angle normal faulting in any of the recent large earthquakes.
On the statistics of SuperDARN autocorrelation function estimates
Authors: Reimer A. S. , Hussey G. C. , Dueck S. R.
Published: May 2016

Time domain signal processing techniques are employed by the Super Dual Auroral Radar Network (SuperDARN) to obtain bulk measurements of the velocity and spectral width of F region ionospheric plasma irregularities. The measurements are obtained by fitting estimates of the mean autocorrelation function (ACF) of the radar target. To accurately and consistently extract target parameters from the mean unnormalized ACF, it is necessary to utilize error‐weighted fitting algorithms with a weight given by the variance of the ACF. Currently implemented weights are ad hoc, and a detailed description of the statistical characterization of SuperDARN ACFs is needed. Following the discussions in Farley (1969) and Woodman and Hagfors (1969), which describe the variance for the mean normalized ACF used with incoherent scatter radars, we present analytic expressions for obtaining the variance of the real and imaginary components of the mean unnormalized SuperDARN ACF. These expressions are based on models by André et al. (1999) and Moorcroft (2004) of the voltage signal received by SuperDARN radars but may be used for other soft target radar systems. An algorithm for obtaining the variance of both the magnitude and phase of the mean ACF is also presented. The results of this study may be directly integrated into existing SuperDARN data analysis software and other pulse‐Doppler radar systems that utilize estimates of the mean unnormalized ACF.
Measurement and modeling of engineered nanoparticle transport and aging dynamics in a reactive porous medium
Authors: Naftaly Aviv , Dror Ishai , Berkowitz Brian
Published: May 2016

A continuous time random walk particle tracking (CTRW‐PT) method was employed to model flow cell experiments that measured transport of engineered nanoparticles (ENPs) in a reactive porous medium. The experiments involved a water‐saturated medium containing negatively charged, polyacrylamide beads, resembling many natural soils and aquifer materials, and having the same refraction index as water. Negatively and positively charged ENPs were injected into a uniform flow field in a 3‐D horizontal flow cell, and the spatial and temporal concentrations of the evolving ENP plumes were obtained via image analysis. As a benchmark, and to calibrate the model, Congo red tracer was employed in 1‐D column and 3‐D flow cell experiments, containing the same beads. Negatively charged Au and Ag ENPs demonstrated migration patterns resembling those of the tracer but were slightly more dispersive; the transport was well represented by the CTRW‐PT model. In contrast, positively charged AgNPs displayed an unusual behavior: establishment of an initial plume of essentially immobilized ENPs, followed by development of a secondary, freely migrating plume. The mobile plume was found to contain ENPs that, with aging, exhibited aggregation and charge inversion, becoming negatively charged and mobile. In this case, the CTRW‐PT model was modified to include a probabilistic law for particle immobilization, to account for the decreasing tendency (over distance and time) of the positively charged AgNPs to attach to the porous medium. The agreement between experimental results and modeling suggests that the CTRW‐PT framework can account for the non‐Fickian and surface‐charge‐dependent transport and aging exhibited by ENPs in porous media.
Configuration‐Dependent Electrically Tunable Van der Waals Heterostructures Based on MoTe2/MoS2
Authors: Wang Feng , Yin Lei , Wang Zhen Xing , Xu Kai , Wang Feng Mei , Shifa Tofik Ahmed , Huang Yun , Jiang Chao , He Jun
Published: May 2016

Van der Waals heterostructures (vdWHs), obtained by artificially stacking 2D layered material (2DLM) plains upon each other, are brand new structures that have exhibited novel electronic and optoelectronic properties and attracted a great deal of attention. So far, the results are only based on devices with symmetrical configurations: devices predominated by vdWH parts, or cross‐like configurations combined with both vdWHs and extra individual 2DLM layers. Quite different gate tunable phenomena have been observed for these two configurations even though 2DLMs with similar band alignments were used, which may be due to the different device configurations utilized. For a deeper understanding, rational investigation on configuration‐dependent properties of vdWHs is needed. Here, using MoTe2/MoS2 as an example, vdWH device is artificially designed with two asymmetrical configurations. Through comparing the respective results, it is found that the properties that stem only from the vdWH, i.e., the rectification behavior and open voltage in photovoltaic effect, are independent of the device structures. However, other properties, i.e., drain currents, short circuit currents, and photoreponse performances, strongly depend on the configuration used. These results give a guideline on studying the intrinsic properties of vdWHs and optimizing the device structures for better performances.
Toward a Magnesium‐Iodine Battery
Authors: Bertasi Federico , Sepehr Fatemeh , Pagot Gioele , Paddison Stephen J. , Di Noto Vito
Published: May 2016

The quest for new electrolyte and cathode materials is a crucial point for beyond‐lithium‐ion energy storage systems. Following this, an electrolyte for secondary magnesium batteries based on a new iodoaluminate ionic liquid and δ‐MgI2 is reported. Promising electrochemical performance in terms of Mg plating‐stripping, coulombic efficiency, and conductivity, demonstrates the potential of this iodine‐based system for future Mg secondary batteries.
Acylperoxycoumarins as ortho‐CH Acylating Agent via a Palladium(II)‐Catalyzed Redox‐Neutral Process
Authors: Ranjan Mohanta Prakash , Banerjee Arghya , Kumar Santra Sourav , Behera Ahalya , Patel Bhisma K.
Published: May 2016

An unprecedented palladium(II)‐catalyzed biomimetic aliphatic acyl (‐COR) group transfer was observed from acyl‐α‐peroxycoumarins to the ortho CH sites of directing arenes. Here, the CH activation is associated with a concomitant acyl group transfer via a Pd(II)‐catalyzed, redox‐neutral process. While methods for ortho aroylation (‐COAr) are well documented ortho acylation (‐COR) processes are scarce, hence the present redox‐neutral method is most ideal for o‐acylation of directing substrates.

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Periodic Organic–Inorganic Halide Perovskite Microplatelet Arrays on Silicon Substrates for Room‐Temperature Lasing
Authors: Liu Xinfeng , Niu Lin , Wu Chunyang , Cong Chunxiao , Wang Hong , Zeng Qingsheng , He Haiyong , Fu Qundong , Fu Wei , Yu Ting , Jin Chuanhong , Liu Zheng , Sum Tze Chien
Published: May 2016

Organic–inorganic metal halide perovskites have recently demonstrated outstanding efficiencies in photovoltaics as well as highly promising performances for a wide range of optoelectronic applications such as lasing, light emission, optical detectors, and even for radiation detection. Key to the realization of functional perovskite micro/nanosystems on the ubiquitous silicon optoelectronics platform is through sophisticated lithography. Despite the rapid progress made in halide perovskite lasing, direct lithographic patterning of perovskite films to form optical cavities on conventional substrates remains extremely challenging. This study realizes room‐temperature high‐quality factor whispering‐gallery‐mode lasing (Q ≈ 1210) from patterned lead halide perovskite microplatelets fabricated in periodic arrays on silicon substrate with micropatterned BN film as the buffer layer. By varying the size of the platelets, modal selectivity for single mode lasing can be achieved with different cavity sizes or by simply breaking the structural symmetry of the cavity through designing the pattern. Importantly, this work demonstrates a straightforward, versatile bottom‐up scalable strategy to realize high‐quality periodic perovskite arrays with variable cavity sizes for large‐area light‐emitting and optical gain applications.
Conquering the Low‐k Death Curve: Insulating Boron Carbide Dielectrics with Superior Mechanical Properties
Authors: Nordell Bradley J. , Nguyen Thuong D. , Keck Christopher L. , Dhungana Shailesh , Caruso Anthony N. , Lanford William A. , Gaskins John T. , Hopkins Patrick E. , Merrill Devin R. , Johnson David C. , Ross Liza L. , Henry Patrick , King Sean W. , Paquette Michelle M.
Published: May 2016

To enable the continued scaling of integrated circuits, the semiconductor industry faces ongoing struggles to implement better low‐dielectric‐constant (low‐k) materials within the interconnect system. One of the biggest challenges to integrating new dielectrics is overcoming the low‐k death curve—that is, the fatal falloff in mechanical properties associated with the low material densities required to achieve low k values. It is shown that amorphous hydrogenated boron carbide (a‐BC:H) films exhibit Young's modulus (E) values between two and ten times greater than those of state‐of‐the‐art Si‐based dielectric materials across a wide range of k values. In particular, optimized a‐BC:H films with moderate k values in the range of 3–4, in addition to possessing outstanding stiffness (E ≈ 100–150 GPa), simultaneously exhibit excellent electrical properties (leakage current of <10–8 A cm–2 at 2 MV cm–1 and breakdown voltage of >5 MV cm–1). Films in this range also demonstrate resistance to Cu diffusion to at least 600 °C, as well as chemical stability and etch properties suitable for low‐k diffusion barrier/etch stop applications.
Liquid Metal Electrodes for Energy Storage Batteries
Authors: Li Haomiao , Yin Huayi , Wang Kangli , Cheng Shijie , Jiang Kai , Sadoway Donald R.
Published: May 2016

The increasing demands for integration of renewable energy into the grid and urgently needed devices for peak shaving and power rating of the grid both call for low‐cost and large‐scale energy storage technologies. The use of secondary batteries is considered one of the most effective approaches to solving the intermittency of renewables and smoothing the power fluctuations of the grid. In these batteries, the states of the electrode highly affect the performance and manufacturing process of the battery, and therefore leverage the price of the battery. A battery with liquid metal electrodes is easy to scale up and has a low cost and long cycle life. In this progress report, the state‐of‐the‐art overview of liquid metal electrodes (LMEs) in batteries is reviewed, including the LMEs in liquid metal batteries (LMBs) and the liquid sodium electrode in sodium‐sulfur (Na–S) and ZEBRA (Na–NiCl2) batteries. Besides the LMEs, the development of electrolytes for LMEs and the challenge of using LMEs in the batteries, and the future prospects of using LMEs are also discussed.
Maldistribution susceptibility of monolith reactors: Case study of glucose hydrogenation performance
Authors: Schubert Markus , Kost Sebastian , Lange Rüdiger , Salmi Tapio , Haase Stefan , Hampel Uwe
Published: May 2016

In this work an ultrafast electron beam X‐ray modality was applied for the first time to characterize the gas–liquid Taylor flow inside each channel of an opaque honeycomb monolith structure (
) for
and
. Significant spatial and temporal deviations in the phase holdup as well as in the gas bubble and liquid slug lengths were found. To evaluate the impact of Taylor flow maldistribution on the reactor performance, the data of more than
unit cells were used to simulate the reactor productivity in the hydrogenation of glucose. The results verify that a monolith reactor solely designed by using superficial velocities and empirical correlations for gas bubble and liquid slug lengths fails significantly in achieving high product selectivity and the desired conversion. The developed methods are a solid base to design and select proper distributors ensuring the favorable flow configurations for specific chemical processes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4346–4364, 2016
The vocal repertoire of Tibetan macaques (Macaca thibetana): A quantitative classification
Authors: Bernstein Sofia K. , Sheeran Lori K. , Wagner R. Steven , Li Jin‐Hua , Koda Hiroki
Published: May 2016

Vocal repertoires are basic and essential components for describing vocal communication in animals. Studying the entire suite of vocal signals aids investigations on the variation of acoustic structure across social contexts, comparisons on the complexity of communication systems across taxa, and in exploration of the evolutionary origins of species‐specific vocalizations. Here, we describe the vocal repertoire of the largest species in the macaque genus, Macaca thibetana. We extracted thirty acoustic parameters from call recordings. Post hoc validation through quantitative analyses of the a priori repertoire classified eleven call types: coo, squawk, squeal, noisy scream, growl, bark, compound squeak, leap coo, weeping, modulated tonal scream, and pant. In comparison to the rest of the genus, Tibetan macaques uttered a wider array of vocalizations in the context of copulations. Previous reports did not include modulated tonal screams and pants during harassment of copulatory dyads. Furthermore, in comparison to the rest of the genus, Tibetan macaque females emit acoustically distinct copulation calls. The vocal repertoire of Tibetan macaques contributes to the literature on the emergence of species‐specific calls in the genus Macaca with potential insights from social, reproductive, and ecological comparisons across species. Am. J. Primatol. 78:937–949, 2016. © 2016 Wiley Periodicals, Inc.
Stereoselective Koenigs–Knorr Glycosylation Catalyzed by Urea
Authors: Sun Lifeng , Wu Xiaowei , Xiong De‐Cai , Ye Xin‐Shan
Published: May 2016

A stereoselective Koenigs–Knorr glycosylation reaction under the catalysis of urea is described. This method is characterized by urea‐mediated hydrogen‐bond activation and subsequent glycosylation with glycosyl chlorides or bromides. Excellent yields and high anomeric selectivity can be achieved in most cases. Moreover, the low α‐stereoselectivity of glycosylations observed when using perbenzylated glucosyl donors can be greatly improved by the addition of tri‐(2,4,6‐trimethoxyphenyl)phosphine (TTMPP).
Molecularly Imprinted Polymer Coated Quantum Dots for Multiplexed Cell Targeting and Imaging
Authors: Panagiotopoulou Maria , Salinas Yolanda , Beyazit Selim , Kunath Stephanie , Duma Luminita , Prost Elise , Mayes Andrew G. , Resmini Marina , Tse Sum Bui Bernadette , Haupt Karsten
Published: May 2016

Advanced tools for cell imaging are of great interest for the detection, localization, and quantification of molecular biomarkers of cancer or infection. We describe a novel photopolymerization method to coat quantum dots (QDs) with polymer shells, in particular, molecularly imprinted polymers (MIPs), by using the visible light emitted from QDs excited by UV light. Fluorescent core–shell particles specifically recognizing glucuronic acid (GlcA) or N‐acetylneuraminic acid (NANA) were prepared. Simultaneous multiplexed labeling of human keratinocytes with green QDs conjugated with MIP‐GlcA and red QDs conjugated with MIP‐NANA was demonstrated by fluorescence imaging. The specificity of binding was verified with a non‐imprinted control polymer and by enzymatic cleavage of the terminal GlcA and NANA moieties. The coating strategy is potentially a generic method for the functionalization of QDs to address a much wider range of biocompatibility and biorecognition issues.
Hybrid Ultra‐Microporous Materials for Selective Xenon Adsorption and Separation
Authors: Mohamed Mona H. , Elsaidi Sameh K. , Pham Tony , Forrest Katherine A. , Schaef Herbert T. , Hogan Adam , Wojtas Lukasz , Xu Wenqian , Space Brian , Zaworotko Michael J. , Thallapally Praveen K.
Published: May 2016

The demand for Xe/Kr separation continues to grow due to the industrial significance of high‐purity Xe gas. Current separation processes rely on energy intensive cryogenic distillation. Therefore, less energy intensive alternatives, such as physisorptive separation, using porous materials, are required. Herein we show that an underexplored class of porous materials called hybrid ultra‐microporous materials (HUMs) affords new benchmark selectivity for Xe separation from Xe/Kr mixtures. The isostructural materials, CROFOUR‐1‐Ni and CROFOUR‐2‐Ni, are coordination networks that have coordinatively saturated metal centers and two distinct types of micropores, one of which is lined by CrO42− (CROFOUR) anions and the other is decorated by the functionalized organic linker. These nets offer unprecedented selectivity towards Xe. Modelling indicates that the selectivity of these nets is tailored by synergy between the pore size and the strong electrostatics afforded by the CrO42− anions.
Capture and Recycling of Sortase A through Site‐Specific Labeling with Lithocholic Acid
Authors: Rosen Christian B. , Kwant Richard L. , MacDonald James I. , Rao Meera , Francis Matthew B.
Published: May 2016

Enzyme‐mediated protein modification often requires large amounts of biocatalyst, adding significant costs to the process and limiting industrial applications. Herein, we demonstrate a scalable and straightforward strategy for the efficient capture and recycling of enzymes using a small‐molecule affinity tag. A proline variant of an evolved sortase A (SrtA 7M) was N‐terminally labeled with lithocholic acid (LA)—an inexpensive bile acid that exhibits strong binding to β‐cyclodextrin (βCD). Capture and recycling of the LA‐Pro‐SrtA 7M conjugate was achieved using βCD‐modified sepharose resin. The LA‐Pro‐SrtA 7M conjugate retained full enzymatic activity, even after multiple rounds of recycling.
A Concise Route to the Strongylophorines
Authors: Yu Wanwan , Hjerrild Per , Overgaard Jacob , Poulsen Thomas B.
Published: May 2016

An efficient eight‐step semisynthesis of strongylophorine‐2 from the abundant building block isocupressic acid is reported. The route represents the first synthetic entry into this class of natural products and provides access to six additional family members. A novel iron(III)‐mediated rearrangement–cyclization cascade and a directed photochemical sp3 C−H δ‐lactonization are the key transformations that enable concise assembly of these bioactive polycyclic meroterpenoids.
Isolating Reactions at the Picoliter Scale: Parallel Control of Reaction Kinetics at the Liquid–Liquid Interface
Authors: Phan‐Quang Gia Chuong , Lee Hiang Kwee , Ling Xing Yi
Published: May 2016

Miniaturized liquid–liquid interfacial reactors offer enhanced surface area and rapid confinement of compounds of opposite solubility, yet they are unable to provide in situ reaction monitoring at a molecular level at the interface. A picoreactor operative at the liquid–liquid interface is described, comprising plasmonic colloidosomes containing Ag octahedra strategically assembled at the water‐in‐decane emulsion interface. The plasmonic colloidosomes isolate ultrasmall amounts of solutions (<200 pL), allowing parallel monitoring of multiple reactions simultaneously. Using the surface‐enhanced Raman spectroscopy (SERS) technique, in situ monitoring of the interfacial protonation of dimethyl yellow (p‐dimethylaminoazobenzene (DY)) is performed, revealing an apparent rate constant of 0.09 min−1 for the first‐order reaction. The presence of isomeric products with similar physical properties is resolved, which would otherwise be indiscernible by other analytical methods.
General Self‐Template Synthesis of Transition‐Metal Oxide and Chalcogenide Mesoporous Nanotubes with Enhanced Electrochemical Performances
Authors: Wang Huan , Zhuo Sifei , Liang Yu , Han Xiling , Zhang Bin
Published: May 2016

The development of a general strategy for synthesizing hierarchical porous transition‐metal oxide and chalcogenide mesoporous nanotubes, is still highly challenging. Herein we present a facile self‐template strategy to synthesize Co3O4 mesoporous nanotubes with outstanding performances in both the electrocatalytic oxygen‐evolution reaction (OER) and Li‐ion battery via the thermal‐oxidation‐induced transformation of cheap and easily‐prepared Co‐Asp(cobalt–aspartic acid) nanowires. The initially formed thin layers on the precursor surfaces, oxygen‐induced outward diffusion of interior precursors, the gas release of organic oxidation, and subsequent Kirkendall effect are important for the appearance of the mesoporous nanotubes. This self‐template strategy of low‐cost precursors is found to be a versatile method to prepare other functional mesoporous nanotubes of transition‐metal oxides and chalcogenides, such as NiO, NiCo2O4, Mn5O8, CoS2 and CoSe2.
Palladium(II)‐Catalyzed Tandem Synthesis of Acenes Using Carboxylic Acids as Traceless Directing Groups
Authors: Kim Kiho , Vasu Dhananjayan , Im Honggu , Hong Sungwoo
Published: May 2016

A straightforward synthetic strategy for generating useful anthracene derivatives was developed involving palladium(II)‐catalyzed tandem transformation with carboxylic acids as traceless directing groups. Carboxyl‐directed C‐H alkenylation, carboxyl‐directed secondary C‐H activation and rollover, intramolecular C−C bond formation, and decarboxylative aromatization are proposed as the key steps in the tandem reaction pathway. This novel synthetic route utilizes a broad range of substrates and provides a convenient synthetic tool that allows access to acenes.
Mesoporous Silica Particles Integrated with All‐Inorganic CsPbBr3 Perovskite Quantum‐Dot Nanocomposites (MP‐PQDs) with High Stability and Wide Color Gamut Used for Backlight Display
Authors: Wang Hung‐Chia , Lin Shin‐Ying , Tang An‐Cih , Singh Bheeshma Pratap , Tong Hung‐Chun , Chen Ching‐Yi , Lee Yu‐Chun , Tsai Tzong‐Liang , Liu Ru‐Shi
Published: May 2016

All‐inorganic CsPbX3 (X=I, Br, Cl) perovskite quantum dots (PQDs) have been investigated because of their optical properties, such as tunable wavelength, narrow band, and high quantum efficiency. These features have been used in light emitting diode (LED) devices. LED on‐chip fabrication uses mixed green and red quantum dots with silicone gel. However, the ion‐exchange effect widens the narrow emission spectrum. Quantum dots cannot be mixed because of anion exchange. We address this issue with a mesoporous PQD nanocomposite that can prevent ion exchange and increase stability. We mixed green quantum‐dot‐containing mesoporous silica nanocomposites with red PQDs, which can prevent the anion‐exchange effect and increase thermal and photo stability. We applied the new PQD‐based LEDs for backlight displays. We also used PQDs in an on‐chip LED device. Our white LED device for backlight display passed through a color filter with an NTSC value of 113 % and Rec. 2020 of 85 %.
Resistance of Cu(Aβ4–16) to Copper Capture by Metallothionein‐3 Supports a Function for the Aβ4–42 Peptide as a Synaptic CuII Scavenger
Authors: Wezynfeld Nina E. , Stefaniak Ewelina , Stachucy Kinga , Drozd Agnieszka , Płonka Dawid , Drew Simon C. , Krężel Artur , Bal Wojciech
Published: May 2016

Aβ4‐42 is a major species of Aβ peptide in the brains of both healthy individuals and those affected by Alzheimer's disease. It has recently been demonstrated to bind CuII with an affinity approximately 3000 times higher than the commonly studied Aβ1‐42 and Aβ1‐40 peptides, which are implicated in the pathogenesis of Alzheimer's disease. Metallothionein‐3, a protein considered to orchestrate copper and zinc metabolism in the brain and provide antioxidant protection, was shown to extract CuII from Aβ1‐40 when acting in its native Zn7MT‐3 form. This reaction is assumed to underlie the neuroprotective effect of Zn7MT‐3 against Aβ toxicity. In this work, we used the truncated model peptides Aβ1‐16 and Aβ4‐16 to demonstrate that the high‐affinity CuII complex of Aβ4‐16 is resistant to Zn7MT‐3 reactivity. This indicates that the analogous complex of the full‐length peptide Cu(Aβ4‐42) will not yield copper to MT‐3 in the brain, thus supporting the concept of a physiological role for Aβ4‐42 as a CuII scavenger in the synaptic cleft.
Electrochemical C−H/N−H Functionalization for the Synthesis of Highly Functionalized (Aza)indoles
Authors: Hou Zhong‐Wei , Mao Zhong‐Yi , Zhao Huai‐Bo , Melcamu Yared Yohannes , Lu Xin , Song Jinshuai , Xu Hai‐Chao
Published: May 2016

Indoles and azaindoles are among the most important heterocycles because of their prevalence in nature and their broad utility in pharmaceutical industry. Reported herein is an unprecedented noble‐metal‐ and oxidant‐free electrochemical method for the coupling of (hetero)arylamines with tethered alkynes to synthesize highly functionalized indoles, as well as the more challenging azaindoles.
Stabilizing a Platinum1 Single‐Atom Catalyst on Supported Phosphomolybdic Acid without Compromising Hydrogenation Activity
Authors: Zhang Bin , Asakura Hiroyuki , Zhang Jia , Zhang Jiaguang , De Sudipta , Yan Ning
Published: May 2016

In coordination chemistry, catalytically active metal complexes in a zero‐ or low‐valent state often adopt four‐coordinate square‐planar or tetrahedral geometry. By applying this principle, we have developed a stable Pt1 single‐atom catalyst with a high Pt loading (close to 1 wt %) on phosphomolybdic acid(PMA)‐modified active carbon. This was achieved by anchoring Pt on the four‐fold hollow sites on PMA. Each Pt atom is stabilized by four oxygen atoms in a distorted square‐planar geometry, with Pt slightly protruding from the oxygen planar surface. Pt is positively charged, absorbs hydrogen easily, and exhibits excellent performance in the hydrogenation of nitrobenzene and cyclohexanone. It is likely that the system described here can be extended to a number of stable SACs with superior catalytic activities.
A Binuclear 1,1′‐Bis(boratabenzene) Complex: Unprecedented Intramolecular Metal–Metal Communication through a B−B Bond
Authors: Braunschweig Holger , Demeshko Serhiy , Ewing William C. , Krummenacher Ivo , Macha Bret B. , Mattock James D. , Meyer Franc , Mies Jan , Schäfer Marius , Vargas Alfredo
Published: May 2016

We report the synthesis of the first 1,1′‐bis(boratabenzene) species by tetrabromodiborane(4)‐induced ring‐expansion reactions of cobaltocene. Six equivalents of cobaltocene are required as the species plays the dual role of reagent and reductant to yield [{(η5‐C5H5)Co}2{μ:η6,η6‐(BC5H5)2}]. The formally dianionic bis(boratabenzene) moiety with a boron–boron single bond can be viewed as a symmetric dimer of the parent boratabenzene anion as well as the first example of a diboron analogue of biphenyl. The solution electrochemistry of the bimetallic complex shows four stepwise redox events, indicating significant intramolecular interaction between the cobalt ions across the 1,1′‐bis(boratabenzene) unit. The magnetic properties, as investigated by variable‐temperature SQUID magnetometry, reveal weak intramolecular antiferromagnetic interactions. Density functional theory calculations support the experimental results and add insight into the various electronic states of the complex.
C−C Coupling of Benzyl Fluorides Catalyzed by an Electrophilic Phosphonium Cation
Authors: Zhu Jiangtao , Pérez Manuel , Stephan Douglas W.
Published: May 2016

The activation and cleavage of benzyl fluorides by the electrophilic organofluorophosphonium catalyst, [(C6F5)3PF][B(C6F5)4], is reported and used for the preparation of 1,1‐diarylalkanes (37 examples) and substituted aryl homoallylic alkenes (14 examples). This procedure involves mild conditions, avoids harmful waste, and is compatible with a range of substituted arenes and allylic silanes.
Flexible polyurethane foams modified with biobased polyols: Synthesis and physical‐chemical characterization
Authors: Soto G. D. , Marcovich N. E. , Mosiewicki M. A.
Published: May 2016

A series of flexible polyurethane foams with different polyol compositions were synthesized through the replacement of a portion of the petroleum‐based polyether polyol with biobased polyols, namely, glycerol (GLY) and hydroxylated methyl esters (HMETO). HMETO was synthesized by the alkaline transesterification of tung oil (TO; obtaining GLY as a byproduct) and the subsequent hydroxylation of the obtained methyl esters with performic acid generated in situ. FTIR spectroscopy, 1H‐NMR, and different analytical procedures indicated that the hydroxyl content increased significantly and the molecular weight decreased with respect to those of the TO after the two reaction steps. The characterization of the obtained foams, achieved through the measurement of the characteristic reaction times, thermal and dynamic mechanical analysis, scanning electronic microscopy, and density measurements, is reported and discussed. The most important changes in the modified foams were found with the addition of GLY to the formulation; this led to an increased foam density and storage rubbery modulus, which were associated with a higher crosslinking density because of the decrease in the chain length between crosslinking points. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43831.
Effects of compatibilizer on the morphological, mechanical, and rheological properties of poly(methyl methacrylate)/poly(N‐methyl methacrylimide) blends
Authors: Kim Ji Mun , Jang Myung Geun , Park Dong Hyup , Kim Woo Nyon
Published: May 2016

The effects of compatibilizer on the morphological, thermal, mechanical, and rheological properties of poly(methyl methacrylate) (PMMA)/poly(N‐methyl methacrylimide) (PMMI) (70/30) blends were investigated. The compatibilizer used in this study was styrene–acrylonitrile–glycidyl methacrylate (SAN‐GMA) copolymer. Morphological characterization of the PMMA/PMMI (70/30) blend with SAN‐GMA showed a decrease in PMMI droplet size with an increase in SAN‐GMA. The glass‐transition temperature of the PMMA‐rich phase became higher when SAN‐GMA was added up to 5 parts per hundred resin by weight (phr). The flexural and tensile strengths of the PMMA/PMMI (70/30) blend increased with the addition of SAN‐GMA up to 5 phr. The complex viscosity of the PMMA/PMMI (70/30) blends increased when SAN‐GMA was added up to 5 phr, which implies an increase in compatibility between the PMMA and PMMI components. From the weighted relaxation spectrum, which was obtained from the storage modulus and loss modulus, the interfacial tension of the PMMA/PMMI (70/30) blend was calculated using the Palierne emulsion model and the Choi‐Schowalter model. The results of the morphological, thermal, mechanical, and rheological studies and the values of the interfacial tension of the PMMA/PMMI (70/30) blends suggest that the optimum compatibilizer concentration of SAN‐GMA is 5 phr. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43856.
Climate‐friendly polyurethane blowing agent based on a carbon dioxide adduct from palmitic acid grafted polyethyleneimine
Authors: Long Yuanzhu , Sun Fuhua , Liu Chao , Huang Dong , Xie Xingyi
Published: May 2016

To explore a new blowing agent for polyurethanes (PUs), palmitic acid was grafted onto a branched polyethyleneimine (bPEI; weight‐average molecular weight = 25,000 Da) via N,N′‐carbonyldiimidazole condensation to form a hydrophobically modified bPEI [palmitic acid grafted branched polyethyleneimine (C16–bPEI)] with a grafting rate of 12%. A CO2 adduct of C16–bPEI, which trapped 16.8% CO2 in it, was synthesized from C16–bPEI. The long alkyl chain grafting improved the dispersibility of the CO2 adduct in the PU raw materials and favored a homogeneous release of CO2 to blow PUs during the exothermic foaming process. The preliminary results show that the foams possessed a density of 72.0 kg/m3 and a compressive strength of 246 kPa; this matched the required values of foams for the thermal insulation of underground steel pipes. This new blowing agent emitted nothing but CO2 to the atmosphere, so it will not promote ozone depletion and will avoid global warming problems that are associated with traditional blowing agents such as chlorofluorocarbons and hydrochloroflourocarbons. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43874.
Plant‐Derived Urease Inhibitors as Alternative Chemotherapeutic Agents
Authors: Hassan Sherif T. S. , Žemlička Milan
Published: May 2016

Inhibition of the metalloenzyme urease has important pharmacologic applications in the field of antiulcer and antigastric cancer agents. Urease is involved in many serious infections caused by Helicobacter pylori in the gastric tract as well as by Proteus and related species in the urinary tract. Although numerous studies have described several novel urease inhibitors (UIs) used for the treatment of gastric and urinary infections, all these compounds have exhibited severe side effects, toxicity, and instability. Therefore, to overcome such problems, it is necessary to search for new sources of UIs, such as natural products, that provide reduced side effects, low toxicity, greater stability, and bioavailability. As limited studies have been conducted on plant‐derived UIs, this paper aims to highlight and summarize the most promising compounds isolated and identified from plants, such as terpenoids, phenolic compounds, alkaloids, and other substances with inhibitory activities against plant and bacterial ureases; these are in vitro and in vivo studies with an emphasis on structure–activity relationship studies and types of inhibition that show high and promising levels of anti‐urease activity. This will aid medicinal chemists in the design and synthesis of novel and pharmacologically potent UIs useful for the development of antiulcer drugs.
Finite‐Time Stabilization of a Class of Cascade Nonlinear Switched Systems
Authors: Su Qingyu , Jia Xiaolong , Liu Honghai
Published: May 2016

This paper investigates the finite‐time stabilization problem for a class of cascade nonlinear switched systems. Using the average dwell time and multiple Lyapunov function technologies, some sufficient conditions to guarantee that the corresponding closed‐loop system is finite‐time stabilized are derived for the switched systems. Via multiple Lyapunov functions, the state feedback controller is designed to finite‐time stabilize a cascade nonlinear switched system, and the conditions are formulated in terms of linear matrix inequalities. An example is given to illustrate the efficiency of the proposed methods.
Spectroscopic studies on the interaction of chromium (VI) and chromium (III) with keyhole limpet hemocyanin
Authors: Fan Yulan , Zeng Guidi , Liu Jingyi , Chen Huifang , Xue Jun , Wu Yongquan , Li Xun
Published: May 2016

The interactions of keyhole limpet hemocyanin (KLH) with chromium nitrate, potassium dichromate, and chromate were investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy under simulated physiological conditions. The experimental results showed that the different forms of chromium could quench the intrinsic fluorescence of KLH following a static quenching mechanism rather than by dynamic collision, which indicated that a Cr–KLH complex was formed. The Stern–Volmer quenching constants for the interaction indicated that the binding reaction of KLH with Cr(VI) was stronger the binding of KLH with Cr(III). The thermodynamic values for binding of Cr(VI) to KLH areΔH > 0 andΔS > 0. By contrast, the values for the interaction of Cr(III) with KLH areΔH < 0 andΔS < 0. The results of synchronous fluorescence, UV–vis absorption and CD spectroscopy showed that theα‐helical secondary structure and conformation of KLH were altered by different forms of chromium. Copyright © 2016 John Wiley & Sons, Ltd.
Optimization of an acetate reduction pathway for producing cellulosic ethanol by engineered yeast
Authors: Zhang Guo‐Chang , Kong In Iok , Wei Na , Peng Dairong , Turner Timothy L. , Sung Bong Hyun , Sohn Jung‐Hoon , Jin Yong‐Su
Published: May 2016

Xylose fermentation by engineered Saccharomyces cerevisiae expressing NADPH‐linked xylose reductase (XR) and NAD+‐linked xylitol dehydrogenase (XDH) suffers from redox imbalance due to cofactor difference between XR and XDH, especially under anaerobic conditions. We have demonstrated that coupling of an NADH‐dependent acetate reduction pathway with surplus NADH producing xylose metabolism enabled not only efficient xylose fermentation, but also in situ detoxification of acetate in cellulosic hydrolysate through simultaneous co‐utilization of xylose and acetate. In this study, we report the highest ethanol yield from xylose (0.463 g ethanol/g xylose) by engineered yeast with XR and XDH through optimization of the acetate reduction pathway. Specifically, we constructed engineered yeast strains exhibiting various levels of the acetylating acetaldehyde dehydrogenase (AADH) and acetyl‐CoA synthetase (ACS) activities. Engineered strains exhibiting higher activities of AADH and ACS consumed more acetate and produced more ethanol from a mixture of 20 g/L of glucose, 80 g/L of xylose, and 8 g/L of acetate. In addition, we performed environmental and genetic perturbations to further improve the acetate consumption. Glucose‐pulse feeding to continuously provide ATPs under anaerobic conditions did not affect acetate consumption. Promoter truncation of GPD1 and gene deletion of GPD2 coding for glycerol‐3‐phosphate dehydrogenase to produce surplus NADH also did not lead to improved acetate consumption. When a cellulosic hydrolysate was used, the optimized yeast strain (SR8A6S3) produced 18.4% more ethanol and 41.3% less glycerol and xylitol with consumption of 4.1 g/L of acetate than a control strain without the acetate reduction pathway. These results suggest that the major limiting factor for enhanced acetate reduction during the xylose fermentation might be the low activities of AADH and ACS, and that the redox imbalance problem of XR/XDH pathway can be exploited for in situ detoxification of acetic acid in cellulosic hydrolysate and increasing ethanol productivity and yield. Biotechnol. Bioeng. 2016;113: 2587–2596. © 2016 Wiley Periodicals, Inc.
Development of simultaneous analysis of tryptophan metabolites in serum and gastric juice – an investigation towards establishing a biomarker test for gastric cancer diagnosis
Authors: Choi Jong Min , Park Won Sang , Song Kyo Young , Lee Hwa Jeong , Jung Byung Hwa
Published: May 2016

To evaluate changes in tryptophan metabolism and discover diagnostic biomarkers for gastric cancer, a quantitative method was developed for tryptophan and its seven metabolites (indole‐3‐lactic acid, anthranilic acid, serotonin, nicotinic acid, kynurenic acid, kynurenine and 3‐indoxyl sulfate) in both human serum and gastric juice using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Serum and gastric juice were prepared with a simple protein precipitation using aqueous 0.1% formic acid and acetonitrile. As a result, it was found that the kynurenine pathway of tryptophan metabolism was activated in gastric cancer and that the metabolic ratio of kynurenine/tryptophan, which reflects the enzyme activity of indoleamine‐2,3‐dioxygenase, was associated with the observed metabolic changes. Finally, the investigation of tryptophan metabolites, especially kynurenic acid, in serum and gastric juice might serve as biomarkers for gastric cancer. The findings in this study provide critical information of tryptophan metabolism which can be applied to a serum‐based diagnostic test for gastric cancer.
Screening and identification of hepatotoxic component in Evodia rutaecarpa based on spectrum–effect relationship and UPLC‐Q‐TOFMS
Authors: Li Wenlan , Sun Xiangming , Liu Bingmei , Zhang Lihui , Fan Ziquan , Ji Yubin
Published: May 2016

Evodia rutaecarpa (E. rutaecarpa) has been used to treat aches, vomiting and dysentery in traditional Chinese medicine. However, as a mildly toxic herb its toxic components have not been elucidated. An attempt was made to illuminate the hepatotoxic constituents of E. rutaecarpa. The 50% ethanol extracts of E. rutaecarpa from 19 different sources were used to establish UPLC fingerprints and administered to mice at a dose of 35 g/kg (crude medicine weight/mouse weight) once daily for 14 days. Serum levels of alanine transaminase, aspartate aminotransferase and liver coefficient were used as indices of liver injury. Additionally, the characteristic peaks of 19 fingerprints were identified. Spectrum–effect relationships between fingerprints and hepatotoxic indicators were analyzed using bivariate correlation analysis (BCA). The UPLC fingerprints were established and a total of 28 main compounds were identified. Because of the inherent variations in chemical compositions, the liver injury levels were different among the E. rutaecarpa samples from 19 sites of production. BCA results indicated that compounds dihydrorutaecarpine, 6‐acetoxy‐5‐epilimonin, goshuyuamide I, 1‐methyl‐2‐[(Z)‐5‐undecenyl]‐4(1H)‐quinolone, 1‐methyl‐2‐[(4Z,7Z)‐4,7‐tridecadienyl]‐4(1H)‐quinolone, evocarpine and 1‐methyl‐2‐[(6Z,9Z)‐6,9‐pentadecadienyl]‐4(1H)‐quinolone were tentatively determined as the primary hepatotoxic components. The present study provides a valuable method for the discovery of hepatotoxic constituents by combination of fingerprints and hepatotoxicity index.
Carbon Flux Trapping: Highly Efficient Production of Polymer‐Grade d‐Lactic Acid with a Thermophilic d‐Lactate Dehydrogenase
Authors: Li Chao , Tao Fei , Xu Ping
Published: May 2016

High production of polymer‐grade d‐lactic acid is urgently required, particularly for the synthesis of polylactic acid. High‐temperature fermentation has multiple advantages, such as lower equipment requirement and energy consumption, which are essential for lowering operating costs. We identified and introduced a unique d‐lactate dehydrogenase into a thermotolerant butane‐2,3‐diol‐producing strain. Carbon flux “trapping” was achieved by a “trapping point” created by combination of the introduced enzyme and the host efflux pump, which afforded irreversible transport of d‐lactic acid. The overall carbon flux of the engineered strain was significantly enhanced and was redistributed predominantly to d‐lactic acid. Under optimized conditions at 50 °C, d‐lactic acid reached the highest titer (226.6 g L−1) reported to date. This discovery allows us to extend the carbon flux trapping strategy to engineering complex metabolic networks.
Photocatalytic Activity of Zirconium‐ and Manganese‐Codoped Titania in Aqueous Media: The Role of the Metal Dopant and its Incorporation Site
Authors: Pliekhov Oleksii , Arčon Iztok , Tušar Nataša Novak , Štangar Urška Lavrenčič
Published: May 2016

The development of efficient TiO2‐based photocatalysts for water treatment is mainly performed by doping with transition metals or by establishing junctions between different phases, metal–semiconductor or semiconductor–semiconductor. We present, for the first time, the synthesis of Zr‐ and Mn‐modified TiO2 by a redesigned sol–gel technique that allows the formation of heterometallic bridges on the TiO2 surface. Cations of the doping metals are located in the pores of mesoporous anatase and attached to the crystalline TiO2 walls. The presence of the Zr enhances the photoactivity of the TiO2 catalyst. However, the introduction of Mn decreases the photocatalytic efficiency in a nonadditive manner. The inhibition effect was assigned to the side reaction between hydroxyl radicals and Mn ions. The fact that Mn effectively scavenges the hydroxyl radicals and, consequently, inhibits the whole oxidation process is direct proof that hydroxyl radicals are the main reactive species in the photocatalytic oxidative processes on TiO2 surfaces in aqueous media and the process of .OH generation is the rate‐determining step, which was confirmed using a method based on the decolorization of a commercial dye Bezaktiv Blau in a reaction with Fenton's reagent as a source of hydroxyl radicals.