bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical study of the alteration of the magnetic structure of magnetic clouds in the Earth's magnetosheath
Authors: Turc L. , Fontaine D. , Escoubet C. P. , Kilpua E. K. J. , Dimmock A. P.
Published: February 2017

The magnetosheath plays a central role in the solar wind‐magnetospheric coupling. Yet the effects of its crossing on solar wind structures such as magnetic clouds (MCs) are generally overlooked when assessing their geoeffectivity. Using 82 MCs observed simultaneously in the solar wind and the magnetosheath, we carry out the first statistical study of the alteration of their magnetic structure in the magnetosheath. For each event, the bow shock properties are obtained from a magnetosheath model. The comparison between the model results and observations shows that in 80% of cases, the MHD‐based model captures well the magnetosheath transition; the other events are discussed separately. We find that just downstream of the bow shock the variation of the magnetic field direction shows a very good anticorrelation (r =− 0.91) with the angle between the upstream magnetic field and the shock normal. We then focus on the magnetic field north‐south component Bz because of its importance for geoeffectivity. Although the sign of Bz is generally preserved in the magnetosheath, we also find evidence of long‐lasting intervals of opposite Bz signs in the solar wind and the magnetosheath during some events, with a |Bz| reversal >10 nT at the magnetopause. We find that these reversals are due to the draping of the field lines and are associated with predominant upstream By. In those cases, the estimated position of the regions of antiparallel fields along the magnetopause is independent of the sign of the upstream Bz. This may have strong implications in terms of reconnection.
Evaluating an impact origin for Mercury's high‐magnesium region
Authors: Frank Elizabeth A. , Potter Ross W. K. , Abramov Oleg , James Peter B. , Klima Rachel L. , Mojzsis Stephen J. , Nittler Larry R.
Published: February 2017

During its four years in orbit around Mercury, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft's X‐ray Spectrometer revealed a large geochemical terrane in the northern hemisphere that hosts the highest Mg/Si, S/Si, Ca/Si, and Fe/Si and lowest Al/Si ratios on the planet. Correlations with low topography, thin crust, and a sharp northern topographic boundary led to the proposal that this high‐Mg region is the remnant of an ancient, highly degraded impact basin. Here we use a numerical modeling approach to explore the feasibility of this hypothesis and evaluate the results against multiple mission‐wide data sets and resulting maps from MESSENGER. We find that an ~3000 km diameter impact basin easily exhumes Mg‐rich mantle material but that the amount of subsequent modification required to hide basin structure is incompatible with the strength of the geochemical anomaly, which is also present in maps of Gamma Ray and Neutron Spectrometer data. Consequently, the high‐Mg region is more likely to be the product of high‐temperature volcanism sourced from a chemically heterogeneous mantle than the remains of a large impact event.
Coupling with ocean mixed layer leads to intraseasonal variability in tropical deep convection: Evidence from cloud‐resolving simulations
Authors: Anber Usama , Wang Shuguang , Sobel Adam
Published: February 2017

The effect of coupling a slab ocean mixed layer to atmospheric convection is examined in cloud‐resolving model (CRM) simulations in vertically sheared and unsheared environments without Coriolis force, with the large‐scale circulation parameterized using the Weak Temperature Gradient (WTG) approximation. Surface fluxes of heat and moisture as well as radiative fluxes are fully interactive, and the vertical profile of domain‐averaged horizontal wind is strongly relaxed toward specified profiles with vertical shear that varies from one simulation to the next. Vertical wind shear is found to play a critical role in the simulated behavior. There exists a threshold value of the shear strength above which the coupled system develops regular oscillations between deep convection and dry nonprecipitating states, similar to those found earlier in a much more idealized model which did not consider wind shear. The threshold value of the vertical shear found here varies with the depth of the ocean mixed layer. The time scale of the spontaneously generated oscillations also varies with mixed layer depth, from 10 days with a 1 m deep mixed layer to 50 days with a 10 m deep mixed layer. The results suggest the importance of the interplay between convection organized by vertical wind shear, radiative feedbacks, large‐scale dynamics, and ocean mixed layer heat storage in real intraseasonal oscillations.
Adaptive multitask network based on maximum correntropy learning algorithm
Authors: Hajiabadi Mojtaba , Hodtani Ghosheh Abed , Khoshbin Hossein
Published: February 2017

Adaptive networks solve distributed optimization problems in which all agents of the network are interested to collaborate with their neighbors to learn a similar task. Collaboration is useful when all agents seek a similar task. However, in many applications, agents may belong to different clusters that seek dissimilar tasks. In this case, nonselective collaboration will lead to damaging results that are worse than noncooperative solution. In this paper, we contribute in problems that several clusters of interconnected agents are interested in learning multiple tasks. To address multitask learning problem, we consider an information theoretic criterion called correntropy in a distributed manner providing a novel adaptive combination policy that allows agents to learn which neighbors they should cooperate with and which other neighbors they should reject. In doing so, the proposed algorithm enables agents to recognize their clusters and to achieve improved learning performance compared with noncooperative strategy. Stability analysis in the mean sense and also a closed‐form relation determining the network error performance in steady‐state mean‐square‐deviation is derived. Simulation results illustrate the theoretical findings and match well with theory.
Generation of a Human Cardiac Patch Based on a Reendothelialized Biological Scaffold (BioVaSc)
Authors: Schürlein Sebastian , Al Hijailan Reem , Weigel Tobias , Kadari Asifiqbal , Rücker Christoph , Edenhofer Frank , Walles Heike , Hansmann Jan
Published: February 2017

Although there are improvements in acute care, ischemic heart disease is the major cause of death worldwide. As a treatment for heart failure or heart infarction, stem cell therapies emerged as a potential therapeutic option. First results have shown moderate improvements and have revealed several limitations, such as an insufficient retention, homing, and engraftment of the cells. These drawbacks result in a loss of cells shortly after implantation. To overcome these hurdles, a human cardiac patch is developed in this work, using a biological collagen‐based vascularized scaffold (BioVaSc®). Endothelial cells are cultured in the pre‐existing vascular structure to establish a physiological blood‐tissue interface. A co‐culture of fibroblasts, mesenchymal stem cells, and induced‐pluripotent‐stem‐cell‐derived cardiomyocytes is seeded on the vascularized scaffold. After two weeks, physiological cardiac functions and expression of cardiac‐specific markers is detected. Moreover, physiological beating rates as well as responsiveness to drug treatment and electrical stimulation is observed. Bioreactor culture facilitates long‐term culture up to four months. Due to its tissue characteristics, the patch constitutes a promising tool for drug development, in addition to its potential in clinical applications.
Heterojunction Photocatalysts
Authors: Low Jingxiang , Yu Jiaguo , Jaroniec Mietek , Wageh Swelm , Al‐Ghamdi Ahmed A.
Published: February 2017

Semiconductor‐based photocatalysis attracts wide attention because of its ability to directly utilize solar energy for production of solar fuels, such as hydrogen and hydrocarbon fuels and for degradation of various pollutants. However, the efficiency of photocatalytic reactions remains low due to the fast electron–hole recombination and low light utilization. Therefore, enormous efforts have been undertaken to solve these problems. Particularly, properly engineered heterojunction photocatalysts are shown to be able to possess higher photocatalytic activity because of spatial separation of photogenerated electron–hole pairs. Here, the basic principles of various heterojunction photocatalysts are systematically discussed. Recent efforts toward the development of heterojunction photocatalysts for various photocatalytic applications are also presented and appraised. Finally, a brief summary and perspectives on the challenges and future directions in the area of heterojunction photocatalysts are also provided.
NASICON‐Structured Materials for Energy Storage
Authors: Jian Zelang , Hu Yong‐Sheng , Ji Xiulei , Chen Wen
Published: February 2017

The demand for electrical energy storage (EES) is ever increasing, which calls for better batteries. NASICON‐structured materials represent a family of important electrodes due to its superior ionic conductivity and stable structures. A wide range of materials have been considered, where both vanadium‐based and titanium‐based materials are recommended as being of great interest. NASICON‐structured materials are suitable for both the cathode and the anode, where the operation potential can be easily tuned by the choice of transition metal and/or polyanion group in the structure. NASICON‐structured materials also represent a class of solid electrolytes, which are widely employed in all‐solid‐state ion batteries, all‐solid‐state air batteries, and hybrid batteries. NASICON‐structured materials are reviewed with a focus on both electrode materials and solid‐state electrolytes.
In Situ Growth of 120 cm2 CH3NH3PbBr3 Perovskite Crystal Film on FTO Glass for Narrowband‐Photodetectors
Authors: Rao Hua‐Shang , Li Wen‐Guang , Chen Bai‐Xue , Kuang Dai‐Bin , Su Cheng‐Yong
Published: February 2017

Organometal trihalide perovskites have been attracting intense attention due to their enthralling optoelectric characteristics. Thus far, most applications focus on polycrystalline perovskite, which however, is overshadowed by single crystal perovskite with superior properties such as low trap density, high mobility, and long carrier diffusion length. In spite of the inherent advantages and significant optoelectronic applications in solar cells and photodetectors, the fabrication of large‐area laminar perovskite single crystals is challenging. In this report, an ingenious space‐limited inverse temperature crystallization method is first demonstrated to the in situ synthesis of 120 cm2 large‐area CH3NH3PbBr3 crystal film on fluorine‐doped tin oxide (FTO) glass. Such CH3NH3PbBr3 perovskite crystal film is successfully applied to narrowband photodetectors, which enables a broad linear response range of 10−4–102 mW cm−2, 3 dB cutoff frequency (f
3 dB) of ≈110 kHz, and high narrow response under low bias −1 V.
Ionic Colloidal Molding as a Biomimetic Scaffolding Strategy for Uniform Bone Tissue Regeneration
Authors: Zhang Jian , Jia Jinpeng , Kim Jimin P. , Shen Hong , Yang Fei , Zhang Qiang , Xu Meng , Bi Wenzhi , Wang Xing , Yang Jian , Wu Decheng
Published: February 2017

Inspired by the highly ordered nanostructure of bone, nanodopant composite biomaterials are gaining special attention for their ability to guide bone tissue regeneration through structural and biological cues. However, bone malformation in orthopedic surgery is a lingering issue, partly due to the high surface energy of traditional nanoparticles contributing to aggregation and inhomogeneity. Recently, carboxyl‐functionalized synthetic polymers have been shown to mimic the carboxyl‐rich surface motifs of non‐collagenous proteins in stabilizing hydroxyapatite and directing intrafibrillar mineralization in‐vitro. Based on this biomimetic approach, it is herein demonstrated that carboxyl functionalization of poly(lactic‐co‐glycolic acid) can achieve great material homogeneity in nanocomposites. This ionic colloidal molding method stabilizes hydroxyapatite precursors to confer even nanodopant packing, improving therapeutic outcomes in bone repair by remarkably improving mechanical properties of nanocomposites and optimizing controlled drug release, resulting in better cell in‐growth and osteogenic differentiation. Lastly, better controlled biomaterial degradation significantly improved osteointegration, translating to highly regular bone formation with minimal fibrous tissue and increased bone density in rabbit radial defect models. Ionic colloidal molding is a simple yet effective approach of achieving materials homogeneity and modulating crystal nucleation, serving as an excellent biomimetic scaffolding strategy to rebuild natural bone integrity.
Hybrid Nanoparticle Pyramids for Intracellular Dual MicroRNAs Biosensing and Bioimaging
Authors: Li Si , Xu Liguang , Sun Maozhong , Wu Xiaoling , Liu Liqiang , Kuang Hua , Xu Chuanlai
Published: February 2017

This study strategically fabricates multifunctional nanopyramids to allow the ultrasensitive quantification of dual microRNAs (miR‐203b and miR‐21) in living cells and their responsive bioimaging in vivo. The nanopyramids, composed of Au‐Cu9S5 nanoparticles (NPs), upconversion NPs (UCNPs), and Ag2S NPs, emit two luminescent signals simultaneously with excitation at 808 nm, arising from the UCNPs at 541 nm in the visible region and from the Ag2S NPs at 1227 nm in the second window of near‐infrared (NIR‐II) region. The upconversion luminescence has a linear relationship with miR‐203b from 0.13 to 54.54 fmol per 10 µgRNA and a limit of detection (LOD) of 0.09 fmol per 10 µgRNA, whereas the Ag2S NP luminescence has a linear relationship with miR‐21 from 0.37 to 43.56 fmol per 10 µgRNA, with a LOD of 0.23 fmol per 10 µgRNA. Significantly, this study demonstrates that the nanopyramids can be successfully used for miRs‐responsive bioimaging in a tumor‐bearing animal model. Furthermore, taking advantage of the photothermal capabilities of pyramids, the tumors can also be eliminated completely. These nanopyramids not only overcome the obstacles in the simultaneous detection of multiple miRs at the cellular level but also provide a cancer theranostic platform in vivo.
2D Materials for Optical Modulation: Challenges and Opportunities
Authors: Yu Shaoliang , Wu Xiaoqin , Wang Yipei , Guo Xin , Tong Limin
Published: February 2017

Owing to their atomic layer thickness, strong light–material interaction, high nonlinearity, broadband optical response, fast relaxation, controllable optoelectronic properties, and high compatibility with other photonic structures, 2D materials, including graphene, transition metal dichalcogenides and black phosphorus, have been attracting increasing attention for photonic applications. By tuning the carrier density via electrical or optical means that modifies their physical properties (e.g., Fermi level or nonlinear absorption), optical response of the 2D materials can be instantly changed, making them versatile nanostructures for optical modulation. Here, up‐to‐date 2D material‐based optical modulation in three categories is reviewed: free‐space, fiber‐based, and on‐chip configurations. By analysing cons and pros of different modulation approaches from material and mechanism aspects, the challenges faced by using these materials for device applications are presented. In addition, thermal effects (e.g., laser induced damage) in 2D materials, which are critical to practical applications, are also discussed. Finally, the outlook for future opportunities of these 2D materials for optical modulation is given.
Defect/Edge‐Selective Functionalization of Carbon Materials by “Direct” Friedel–Crafts Acylation Reaction
Authors: Seo Jeong‐Min , Tan Loon‐Seng , Baek Jong‐Beom
Published: February 2017

Popularly utilized oxidation media, via nitric acid/sulfuric acid mixtures, are too corrosive and oxidizing to preserve structural integrity of highly ordered graphitic materials (carbon nanotubes (CNTs) and graphene). Here, for the most commonly used oxidation method, the important advantages of defect/edge‐selective functionalization of carbon materials (CNTs/graphene/graphite) in a polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) medium are elucidated. The optimized PPA/P2O5 medium is a mild acid that is not only less corrosive than popularly utilized oxidation media, but also has a strong capability to drive Friedel–Crafts acylation by covalently modifying carbon materials. With a broader spectrum of functional groups accessible, the PPA/P2O5‐driven Friedel–Crafts acylation offers more options for tailoring the properties and processing of carbon materials.
How the Molecular Packing Affects the Room Temperature Phosphorescence in Pure Organic Compounds: Ingenious Molecular Design, Detailed Crystal Analysis, and Rational Theoretical Calculations
Authors: Xie Yujun , Ge Yuwei , Peng Qian , Li Conggang , Li Qianqian , Li Zhen
Published: February 2017

Long‐lived phosphorescence at room temperature (RTP) from pure organic molecules is rare. Recent research reveals various crystalline organic molecules can realize RTP with lifetimes extending to the magnitude of second. There is little research on how molecular packing affecting RTP. Three compounds are designed with similar optical properties in solution, but tremendously different solid emission characteristics. By investigating the molecular packing arrangement in single crystals, it is found that the packing style of the compact face to face favors of long phosphorescence lifetime and high photoluminescence efficiency, with the lifetime up to 748 ms observed in the crystal of CPM ((9H‐carbazol‐9‐yl)(phenyl)methanone). Theoretical calculation analysis also reveals this kind of packing style can remarkably reduce the singlet excited energy level and prompt electron communication between dimers. Surprisingly, CPM has two very similar single crystals, labeled as CPM and CPM‐A, with almost identical crystal data, and the only difference is that molecules in CPM‐A crystal take a little looser packing arrangement. X‐ray diffraction and cross‐polarization under magic spinning 13C NMR spectra double confirm that they are different crystals. Interestingly, CPM‐A crystal shows negligible RTP compared to the CPM crystal, once again proving that the packing style is critical to the RTP property.
Coupling Surface Plasmon Polariton Modes to Complementary THz Metasurfaces Tuned by Inter Meta‐Atom Distance
Authors: Keller Janine , Maissen Curdin , Haase Johannes , Paravicini‐Bagliani Gian Lorenzo , Valmorra Federico , Palomo José , Mangeney Juliette , Tignon Jérôme , Dhillon Sukhdeep S. , Scalari Giacomo , Faist Jérôme
Published: February 2017

The authors study the interaction of complementary terahertz (THz) split ring resonators with THz surface plasmon polaritons (SPPs) as a function of the meta‐atom distance. The THz transmission properties of 15 samples for which the array dimensions are varied keeping the resonator shape constant are investigated. The linewidth of the inductive‐capacitive (LC‐)resonance is decreasing with increasing meta‐atom distance, up to the frequency matching with the first SPP‐mode. The SPP‐mode couples to the narrow LC‐resonance leading to an anti‐crossing of the modes. In contrast, the narrow SPP‐mode tunes across the broader dipole‐like mode in orthogonal polarization. The excitation direction of the SPP‐mode is found to lie along the electric field polarization of the THz.
An Innovative Postdeposition Annealing Approach Producing Centimeter‐Scale In2O3/In2(TeO3)3 Bulk Heterojunction Thin Film for Room‐Temperature Persistent Photoconductivity
Authors: Yao Jiandong , Zheng Zhaoqiang , Yang Guowei
Published: February 2017

Persistent photoconductivity holds great significance to a variety of interesting applications. However, persistent photoconductivity devices based on large‐scale thin films produced by a facile and efficient technology have rarely been achieved so far. In this work, centimeter‐scale In2O3/In2(TeO3)3 bulk heterojunction thin films are prepared via an innovative and convenient two‐step approach, an initial pulsed‐laser deposition followed by a postdeposition annealing process. A prototype optoelectronic device is fabricated and it exhibits pronounced persistent photoconductivity with positive dependence on both the source–drain voltage and incident power density. This device also shows photoresponse to incident light with wavelengths from ultraviolet to red, revealing great potential for practical device applications such as optoelectronic memory and imaging. A physical model in agreement with the observed phenomena is built to qualitatively illustrate the occurrence of the persistent photoconductivity in the bulk heterojunction system. In addition, the facile two‐step approach is further applied to flexible mica substrates and the persistent photoconductivity is maintained upon tens of bending cycles, which not only demonstrates potential for wearable device but also provides tunable and extended focus range for the photoexcitation. These findings provide an innovative and universal scenario for the development of persistent photoconductivity.
Improving Perovskite Solar Cells: Insights From a Validated Device Model
Authors: Sherkar Tejas S. , Momblona Cristina , Gil‐Escrig Lidón , Bolink Henk J. , Koster L. Jan Anton
Published: February 2017

To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of contacts, the electron and hole transport layers, charge generation, drift and diffusion of charge carriers and recombination. The simulation to the experimental data of vacuum‐deposited CH3NH3PbI3 solar cells over multiple thicknesses has been fit and the device behavior under different operating conditions has been studied to delineate the influence of the external bias, charge‐carrier mobilities, energetic barriers for charge injection/extraction and, different recombination channels on the solar cell performance. By doing so, a unique set of material parameters and physical processes that describe these solar cells is identified. Trap‐assisted recombination at material interfaces is the dominant recombination channel limiting device performance and passivation of traps increases the power conversion efficiency (PCE) of these devices by 40%. Finally, guidelines to increase their performance have been issued and it is shown that a PCE beyond 25% is within reach.
Highly Enantioselective Synthesis of (R)‐3‐Alkyl‐3‐hydroxyindolin‐2‐ones Including Natural Product (R)‐Convolutamydine A Catalyzed by A Primary Amine
Authors: Guo Jun‐Tao , Zhang Bao‐Qiang , Luo Yuan , Guan Zhi , He Yan‐Hong
Published: February 2017

An efficient strategy for constructing (R)‐3‐alkyl‐3‐hydroxyindolin‐2‐one derivatives catalyzed by a structurally simple and easily prepared primary amine catalyst under mild conditions has been developed. Various isatins and ketones were tolerated, and the desired products were obtained in up to 99 % yield and up to 99 % ee. The biologically active natural product (R)‐convolutamydine A was synthesized in 96 % yield and 95 % ee.
Two‐Dimensional Semiconductors Grown by Chemical Vapor Transport
Authors: Hu Dake , Xu Guanchen , Xing Lei , Yan Xingxu , Wang Jingyi , Zheng Jingying , Lu Zhixing , Wang Peng , Pan Xiaoqing , Jiao Liying
Published: February 2017

Developing controlled approaches for synthesizing high‐quality two‐dimensional (2D) semiconductors is essential for their practical applications in novel electronics. The application of chemical vapor transport (CVT), an old single‐crystal growth technique, has been extended from growing 3D crystals to synthesizing 2D atomic layers by tuning the growth kinetics. Both single crystalline individual flakes and continuous films of 1 L MoS2 were successfully obtained with CVT approach at low growth temperatures of 300–600 °C. The obtained 1 L MoS2 exhibits high crystallinity and comparable mobility to mechanically exfoliated samples, as confirmed by both atomic resolution microscopic imaging and electrical transport measurements. Besides MoS2, this method was also used in the growth of 2D WS2, MoSe2, MoxW1−xS2 alloys, and ReS2, thus opening up a new way for the controlled synthesis of various 2D semiconductors.
Influence of oxygen ion implantation on the free volume parameters and electrical conductivity of a polymer‐based bakelite RPC detector material
Authors: Aneesh Kumar K. V. , Kumaraswamy G. N. , Ranganathaiah C. , Ravikumar H. B.
Published: February 2017

We have investigated the effect of ion implantation on structural modification and the electrical conductivity of Bakelite‐resistive plate chamber (RPC) detector material used in high energy physics experiments. Samples of Bakelite polymer were exposed to 100 keV and 150 keV oxygen ions in the fluence of 1012 to 1015 ions cm−2. Ion implantation induced microstructural changes have been studied using positron annihilation lifetime spectroscopy, X‐ray diffraction and Fourier transform infrared techniques. Positron lifetime parameters viz., o‐Ps lifetime and its intensity showed formation of radicals, secondary ions due to the creation of interior tracks by high‐energy ions followed by chain scission at lower fluence of 100 keV implantation. The decreased free volume size at 150 keV ion implantation is an indication of crosslinking and filling up of interior tracks by the implanted ions. Variation of ac conductivity with frequency obeys Jonscher power law at 100 keV and the conduction mechanism is explained by barrier hopping model. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44962.
An Efficient Synthesis of bi‐Aryl Pyrimidine Heterocycles: Potential New Drug Candidates to Treat Alzheimer's Disease
Authors: Rehman Tanzeel Ur , Khan Islam Ullah , Ashraf Muhammad , Tarazi Hamadeh , Riaz Sadaf , Yar Muhammad
Published: February 2017

A series of 13 novel pyrimidine‐based sulfonamides 6a–m were synthesized in short periods of time under microwave conditions in good to excellent yield (54–86%). The chemical structures of these heterocycles consist of a central pyrimidine ring having a phenyl group and pyrimidine groups with sulfonamide motifs. The enzyme inhibitory potential of these compounds was investigated against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) because these enzymes play a crucial role in the treatment of Alzheimer's disease. As compared to the reference compound eserine (IC50 = 0.04 ± 0.0001 μM for AChE and IC50 = 0.85 ± 0.0001 μM for BChE), the IC50 values of the synthesized compounds ranged from 3.73 ± 0.61 μM to 57.36 ± 0.22 μM for AChE and 4.81 ± 0.16 μM to 111.61 ± 0.53 μM for BChE. Among these tested compounds, 6j having a −CH3 group was found to be the most potent one against both enzymes (AChE, IC50 = 3.73 ± 0.61 μM; BChE, IC50 = 4.81 ± 0.16 μM). Quantitative structure–activity relationship (QSAR) and molecular docking studies of the synthesized compounds were also performed.
Interaction of Approved Drugs with Synaptic Vesicle Protein 2A
Authors: Danish Azeem , Namasivayam Vigneshwaran , Schiedel Anke C. , Müller Christa E.
Published: February 2017

Levetiracetam (LEV) and its recently approved derivative brivaracetam are anti‐epileptic drugs with a unique mechanism of action. The synaptic vesicle protein 2A (SV2A) was previously identified as their main target. In the current study, we tested a collection of 500 approved drugs for interaction with the human SV2A protein expressed in Chinese hamster ovary cells. Competition binding studies were performed using cell lysates with high SV2A expression and [3H]brivaracetam as a radioligand. A hit rate of 3% was obtained, defined as compounds that inhibited radioligand binding by more than 90% at a screening concentration of 20 μM. Subsequent concentration–inhibition curves revealed the antihistaminic prodrug loratadine (Ki = 1.16 μM) and the antimalarial drug quinine (Ki = 2.03 μM) to be the most potent SV2A protein ligands of the investigated drug library. Both compounds were similarly potent as LEV (Ki = 1.74 μM), providing structurally novel scaffolds for SV2A ligands. A pharmacophore model was established, which indicated steric and electronic conformities of brivaracetam with the new SV2A ligands, and preliminary structure–activity relationships were determined. The anti‐convulsive effects of the natural product quinine may – at least in part – be explained by interaction with SV2A. Loratadine and quinine represent new lead structures for anti‐epileptic drug development.
Boron Complexes of Glyoxal‐Derived Ugi Adducts as a New Class of Aggregation‐Induced Emission Photoluminescent Materials
Authors: Wei Huiping , Wang Gaigai , Wang Yingchun , Li Binbin , Huang Jianjun , Kashtanov Stepan , Van Hecke Kristof , Pereshivko Olga P. , Peshkov Vsevolod A.
Published: February 2017

A series of O,O‐chelated boron complexes was prepared through a four‐component Ugi reaction followed by complexation of the resulting 1,3‐dicarbonyl compounds with boron trifluoride diethyl etherate. The optical properties of these novel luminophores were investigated by UV/Vis spectroscopy and spectrofluorometry, revealing pronounced aggregation‐induced emission (AIE) features.
Synthesis and Exploration of Ladder‐Structured Large Aromatic Dianhydrides as Organic Cathodes for Rechargeable Lithium‐Ion Batteries
Authors: Xie Jian , Chen Wangqiao , Wang Zilong , Jie Kenneth Choo Wei , Liu Ming , Zhang Qichun
Published: February 2017

Compared to anode materials in Li‐ion batteries, the research on cathode materials is far behind, and their capacities are much smaller. Thus, in order to address these issues, we believe that organic conjugated materials could be a solution. In this study, we synthesized two non‐polymeric dianhydrides with large aromatic structures: NDA‐4N (naphthalenetetracarboxylic dianhydride with four nitrogen atoms) and PDA‐4N (perylenetetracarboxylic dianhydride with four nitrogen atoms). Their electrochemical properties have been investigated between 2.0 and 3.9 V (vs. Li+/Li). Benefiting from multi‐electron reactions, NDA‐4N and PDA‐4N could reversibly achieve 79.7 % and 92.3 %, respectively, of their theoretical capacity. Further cycling reveals that the organic compound with a relatively larger aromatic building block could achieve a better stability, as an obvious 36.5 % improvement of the capacity retention was obtained when the backbone was switched from naphthalene to perylene. This study proposes an opportunity to attain promising small‐molecule‐based cathode materials through tailoring organic structures.
Ionic Self‐Assembled Platform of Perylenediimide–Sodium Dodecylsulfate for Detection of Spermine in Clinical Samples
Authors: Singh Prabhpreet , Mittal Lalit Singh , Bhargava Gaurav , Kumar Subodh
Published: February 2017

The detection and quantification of spermine in clinical practice is important for early diagnosis of many diseases. Chromatographic and immunoassay‐based methods are commonly used. However, a fluorescence‐based assay could provide real‐time detection. Herein, the synthesis and aggregation properties of a dicationic perylene probe (N1‐dodecyl‐N3‐(4‐phenyl)benzimidazolium‐functionalized perylenediimide (DAB‐PDI)) used to develop a fluorescent “turn‐on” ensemble for the detection of spermine are discussed. The fluorescence of DAB‐PDI (10 μm, Φ=0.55) is efficiently quenched by negatively charged sodium dodecylsulfate (SDS) through the formation of ionic self‐assembled aggregates (charge ratio of negative (N) in SDS to positive (P) in DAB‐PDI (N/P)=9). This negatively charged ionic self‐assembly between DAB‐PDI and SDS has been characterized by using photophysical, microscopic, dynamic light scattering, isothermal titration calorimetry, and HRMS techniques. The addition of spermine to this ensemble solution results in the breakdown of the DAB‐PDI–SDS ensemble owing to strong binding of spermine with SDS and, as a result, the fluorescence of DAB‐PDI is recovered. This ensemble exhibits high sensitivity and selectivity for spermine detection in water, urine, and blood serum. The lowest limit of detection is 27.5 nm, which is at least about 36 times lower than that required for early diagnosis of cancer (1 to 10 μm for urinary spermine).
Immobilization of horseradish peroxidase on ZnO nanowires/macroporous SiO2 composites for the complete decolorization of anthraquinone dyes
Authors: Sun Huaiyan , Jin Xinyu , Jiang Feng , Zhang Ruifeng
Published: February 2017

A zinc oxide (ZnO) nanowires/macroporous silicon dioxide composite was used as support to immobilize horseradish peroxidase (HRP) simply by in situ cross‐linking method. As cross‐linker was adsorbed on the surface of ZnO nanowires, the cross‐linked HRP was quite different from the traditional cross‐linking enzyme aggregates on both structure and catalytic performance. Among three epoxy compounds, diethylene glycol diglycidyl ether (DDE) was the best cross‐linker, with which the loading amount of HRP with pI of 5.3 reached as high as 118.1 mg/g and specific activity was up to 14.9 U/mg‐support. The mass loss of HRP cross‐linked with DDE was negligible during 50‐H leaching at 4 °C, and the thermal stability of the immobilized HRP was also quite good. The catalytic performance of immobilized HRP to decolorize anthraquinone dye was explored by using Reactive Blue 19 (RB 19) and Acid Violet 109 (AV 109) as model substrates. The results indicated that the immobilized HRP exhibited high decolorization efficiency and good reusability. The decolorization efficiency reached 94.3% and 95.9% for AV 109 and RB 19 within the first 30 Min, respectively. A complete decolorization of these two dyes has been realized within 2–3 H by using this new biocatalysis system.
Enzymatic characterization and functional implication of two structurally different isocitrate dehydrogenases from Xylella fastidiosa
Authors: Lv Peipei , Tang Wanggang , Wang Peng , Cao Zhengyu , Zhu Guoping
Published: February 2017

Isocitrate dehydrogenase (IDH) is a key enzyme at the critical junction between the tricarboxylic acid cycle and the glyoxylate cycle. Most bacteria have only one IDH, while a few contain two IDH isozymes. The coexistence of two different type IDHs in one organism was little known. Xylella fastidiosa is a nutritionally fastidious plant pathogen that contains two structurally different IDHs, an NAD+‐dependent homodimeric IDH (diXfIDH) and an NADP+‐dependent monomeric IDH (monoXfIDH). Kinetic characterization showed that diXfIDH displayed 206‐fold preferences for NAD+ over NADP+, while monoXfIDH showed 13,800‐fold preferences for NADP+ over NAD+. The putative coenzyme crucial amino acids (Asp‐268, Ile‐269, and Ala‐275 in diXfIDH, and Lys‐589, His‐590, and Arg‐601 in monoXfIDH) were studied by site‐directed mutagenesis. The coenzyme specificities of the three diXfIDH mutants (D268K, D268K/I269Y, and D268K/I269Y/A275V) were switched successfully from NAD+ to NADP+. Meanwhile, the mutant monoXfIDHs (H590L/R601L and K589T/H590L/R601L) greatly reduced the affinity for NADP+, but failed to improve the ability to use NAD+ and had similar affinity to NADP+ and NAD+. The biochemical properties of diXfIDH and monoXfIDH were investigated in detail. This study gives a further insight into the determinants of the coenzyme specificity in both monomeric and dimeric forms of IDHs.
Association between a Maternal History of Miscarriages and Birth Defects
Authors: Campaña Hebe , Rittler Monica , Gili Juan A. , Poletta Fernando A. , Pawluk Mariela S. , Gimenez Lucas G. , Cosentino Viviana R. , Castilla Eduardo E. , Camelo Jorge S. López
Published: February 2017

BACKGROUND

Some studies, mainly in the older literature, observed a significant association between miscarriages and birth defects (BDs) occurring in the same sibship. However, few studies examined the BD/miscarriage relationship in depth. In addition nothing has been added to the underlying mechanisms possibly linking both events. The purpose of this work was to identify specific BDs associated with maternal miscarriages. In particular, it examined whether the risk depended on the number of losses, and to suggest the existence of specific factors for each BD/miscarriage association observed.

METHODS

The study relied on the Latin American Collaborative Study on Congenital Malformations (ECLAMC) database registries including 26,906 live and stillborn infants with one of 19 selected isolated BDs and 93,853 normal controls. Infants born to primigravid mothers were excluded from the present study. Demographic and reproductive variables were compared between control mothers With and Without previous miscarriages. The number, frequency, and distribution of miscarriages were observed for each BD and controls. A conditional logistic regression was applied to evaluate the miscarriage risk for each BD.

RESULTS

Control mothers with previous miscarriages were older, had had more pregnancies, and were less educated. Three risk patterns of miscarriages were observed: a very high risk of miscarriages associated with gastroschisis, omphalocele, and talipes; only one miscarriage associated with spina bifida, and two or more miscarriages associated with hypospadias.

CONCLUSION

These three patterns suggest that different factors underly each BD/miscarriage association: infertility for hypospadias, vascular disruption for gastroschisis and talipes, while for spina bifida, the much debated trophoblastic cell residue theory could not be discarded. Birth Defects Research 109:254–261, 2017. © 2017 Wiley Periodicals, Inc.
Air pollution, neighborhood acculturation factors, and neural tube defects among Hispanic women in California
Authors: Padula Amy M. , Yang Wei , Carmichael Suzan L. , Lurmann Frederick , Balmes John , Hammond S. Katharine , Shaw Gary M.
Published: February 2017

Background

Neural tube defects (NTDs) are one of the most common types of birth defects. Environmental pollutants and acculturation have been associated with NTDs independently. The potential effect modification of acculturation in the relationship between ambient air pollution and risks of NTDs is not well understood.

Methods

We investigated whether associations between traffic‐related air pollutant exposure in early gestation and NTDs, and more specifically spina bifida, were modified by individual and neighborhood acculturation factors among 139 cases and 466 controls born in the San Joaquin Valley of California, 1997 to 2006. Five criteria pollutant exposures in tertiles, two outcomes, and seven neighborhood acculturation factors from the U.S. Census at the block group level were included for a total of 280 investigated associations. Estimates were adjusted for maternal education and multivitamin use in the first 2 months of pregnancy. Additional analyses were stratified by nativity.

Results

Increased odds of NTDs were observed for individuals who had high exposures to carbon monoxide, nitrogen oxide, or nitrogen dioxide and lived in neighborhoods that were more acculturated. Conversely, there were increased odds of NTDs for those who had high prenatal exposure to PM10 and lived in neighborhoods that were less acculturated. The results of spina bifida alone were generally stronger in magnitude. When stratified by individual nativity (U.S.‐ vs. foreign‐born), carbon monoxide, nitrogen oxide, and nitrogen dioxide were more strongly associated with NTDs among U.S.‐born Hispanic mothers.

Conclusion

Neighborhood acculturation factors were modifiers of the relationship between air pollution and NTDs in California, though not in a consistent direction for all pollutants. Birth Defects Research 109:403–422, 2017. © 2017 Wiley Periodicals, Inc.
Associations between the NOGGIN rs227731 polymorphism and NSCL/P risk may be associated with ethnicities: A meta‐analysis
Authors: Wang Feilong , Jiang Ying , Yang Sheng , Liu Qin , Lin Juhong , Zhang Hongmei
Published: February 2017

Background

The aim of this study was to evaluate the association between the noggin rs227731 polymorphism on chromosome 17q22 and risk of nonsyndromic cleft lip with or without palate (NSCL/P).

Methods

Three online databases were searched, including Embase, PubMed, and Chinese National Knowledge Infrastructure. The strength of the associations was evaluated by odds ratios (ORs) and 95% confidence intervals (CIs). We also made a subgroup analysis to explore sources of heterogeneity.

Results

Nine comparisons from seven studies were included in this meta‐analysis. We used five genetic models and found that the noggin rs227731 polymorphism may increase NSCL/P risk in Caucasians: C versus A: OR = 1.43, 95% CI, 1.30–1.58; CC versus AA: OR = 2.00, 95% CI, 1.59–2.52; CA versus AA: OR = 1.50, 95% CI, 1.27–1.77; CC+CA versus AA: OR = 1.64, 95% CI, 1.40–1.92; CC versus CA+AA: OR = 1.56, 95% CI, 1.30–1.87. However, for the Chinese population, no significant association between the rs227731 polymorphism and NSCL/P risk was found: C vs. A: OR = 1.04, 95% CI, 0.81–1.33; CC vs. AA: OR = 1.01, 95% CI, 0.52–1.95; CA vs. AA: OR = 1.03, 95% CI, 0.75–1.40; CC+CA vs. AA: OR = 1.04, 95% CI, 0.76–1.43; CC vs. CA+AA: OR = 1.01, 95% CI, 0.56–1.81.

Conclusion

Our meta‐analysis suggested that the rs227731 polymorphism may increase NSCL/P risk in Caucasians and may have no significant association in the Chinese population. Effects of individual and environmental risk factors and of gene–environment interactions may play a different role in Caucasians than in the Chinese population. More relevant case–control studies are required to obtain more precise results. Birth Defects Research 109:445–451, 2017. © 2017 Wiley Periodicals, Inc.
Magnetic resonance examination of patients with implanted pacemakers: An evaluation of magnetic field gradients slew rate
Authors: Trevisan Diego , Miori Gloria , Correale Armando , Libralon Davide
Published: February 2017

Performing safe magnetic resonance imaging of patients with “MR conditional” pacemakers needs to meet some specific restrictions. One of these is related to the slew rate (SR) parameter, defined as the speed of magnetic field gradients rising up to their required strengths. Unfortunately, SR values cannot be easily checked at the tomograph console. The present work provides an accurate evaluation of the maximum SR for a set of widely used clinical MR sequences. The experimental approach is based on indirect measurement of time‐varying spatial magnetic field gradients. All MR sequences evaluated match safety SR prescriptions. Moreover, an appropriate choice of sequence scan parameters defines some optimized scan protocols tailored for the tomograph considered in the present study. Bioelectromagnetics. 38:307–314, 2017. © 2017 Wiley Periodicals, Inc.
Effects of response independent delivery of preferred items and the high‐probability instructional sequence on compliance
Authors: Lipschultz Joshua , Wilder David A. , Enderli Amy
Published: February 2017

The use of the high‐probability (high‐p) instructional sequence to increase compliance, which includes issuing a series of instructions with which a participant is likely to comply immediately before issuing a low‐probability instruction, has received mixed support in the literature. Previous research has suggested that the delivery of response independent reinforcement may be as effective to increase compliance, at least for some types of instructions. In this study, we examined the effects of response independent reinforcement and the high‐p sequence on compliance with two types of instructions with two young children. Results show that neither procedure was effective for increasing compliance for either type of instruction; however, contingent access to a high preference item increased compliance. Results are discussed in terms of the conditions under which response independent delivery of high‐preference items and the high‐p instructional sequence might be effective to increase compliance.
Binding of hydroxylated polybrominated diphenyl ethers with human serum albumin: Spectroscopic characterization and molecular modeling
Authors: Yang Lulu , Yang Wu , Wu Zhiwei , Yi Zhongsheng
Published: February 2017

Three hydroxylated polybrominated diphenyl ethers (OH‐PBDEs), 3‐OH‐BDE‐47, 5‐OH‐BDE‐47, and 6‐OH‐BDE‐47, were selected to investigate the interactions between OH‐PBDEs with human serum albumin (HSA) under physiological conditions. The observed fluorescence quenching can be attributed to the formation of complexes between HSA and OH‐PBDEs. The thermodynamic parameters at different temperatures indicate that the binding was caused by hydrophobic forces and hydrogen bonds. Molecular modeling and three‐dimensional fluorescence spectrum showed conformational and microenvironmental changes in HSA. Circular dichroism analysis showed that the addition of OH‐PBDEs changed the conformation of HSA with a minor reduction in α‐helix content and increase in β‐sheet content. Furthermore, binding distance r between the donor (HSA) and acceptor (three OH‐PBDEs) calculated using Förster's nonradiative energy transfer theory was <7 nm; therefore, the quenching mechanisms for the binding between HSA and OH‐PBDEs involve static quenching and energy transfer. Combined with molecular dynamics simulations, the binding free energies (ΔGbind) were calculated using molecular mechanics/Poisson − Boltzmann surface area method, and the crucial residues in HSA were identified.
Copper nanocluster‐enhanced luminol chemiluminescence for high‐selectivity sensing of tryptophan and phenylalanine
Authors: Borghei Yasaman‐Sadat , Hosseini Morteza , Khoobi Mehdi , Ganjali Mohammad Reza
Published: February 2017

A remarkable method for the highly sensitive detection of phenylalanine and tryptophan based on a chemiluminescence (CL) assay was reported. It was found that fluorescent copper nanoclusters capped with cysteine (Cys‐CuNCs) strongly enhance the weak CL signal resulting from the reaction between luminol and H2O2. Of the amino acids tested, phenylalanine and tryptophan could enhance the above CL system sensitively. Under optimum conditions, this method was satisfactorily described by a linear calibration curve over a range of 1.0 × 10−6 to 2.7 × 10−5 M for phenylalanine and 1.0 × 10−7 to 3.0 × 10−5 M for tryptophan, respectively. The effect of various parameters such as Cys‐CuNC concentration, H2O2 concentration and pH on the intensity of the CL system were also studied. The main experimental advantage of the proposed method was its selectivity for two amino acids compared with others. To evaluate the applicability of the method to the analysis of a real biological sample it was used to determine tryptophan and phenylalanine in human serum and remarkable results were obtained.
Leuchterblume täuscht Bestäuber durch Duft verwundeter Bienen
Authors: Sudhaus Walter
Published: February 2017

Die Gleitfallen‐Blüten der Leuchterblumen (Ceropegia) betreiben chemische Mimikry, um kleine kleptoparasitische Fliegen als Bestäuber anzulocken. Bei C. sandersonii entspricht der Blütenduft genau den flüchtigen Substanzen, die einer gefangenen oder frisch getöteten Honigbiene entströmen, an der ihr Hauptbestäuber – das Weibchen der Nistfliege Desmometopa – saugt.
RIP, CLIP, CRAC: Analyse von RNA‐Proteinkomplexen
Authors: Haag Sara
Published: February 2017

Wer bei CRAC an Kokain oder eine Computerlüftungsanalge (computer room air conditioning) denkt, für wen CLIP ein Videoclip, eine Büroklammer oder eine Haarspange ist, und wer bei RIP einen Artikel über Grabinschriften (Requiescat in pace) erwartet, liegt falsch. Hier geht es um Methoden zur Identifikation von Protein‐Bindestellen auf RNA!