bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Radar Imagery to Tectonic, Structural and Geological Studies in Afikpo Basin, Southeastern Benue Trough, Nigeria
Authors: Odigi Minapuye Isaac , Momta Prince Suka
Published: April 2019

Radar imagery was used to identify geological features and the production of geological maps of the Afikpo basin. The essence of this study was to delineate significant geological and geomorphological features that have not been imaged by the traditional ground field mapping. The application of Radar imagery technique will be relevant to the discovery of subsurface structures that will aid the accumulation or concentration of certain economic minerals or natural resources. It will enhance the identification of significant geological information such as lineaments, geologic structures, drainages, etc, that will serve as a guide to the actual ground field work investigation. Results from radar imageries revealed drainage pattern, major geomorphological units, mega lithostratigraphic units, lineaments and structures. The geology of Afikpo basin consist of Cretaceous, Tertiary and Quaternary rocks are recognizable; the highly deformed Cretaceous rocks are characterized by regional lineaments. Some of the rivers are aligned along the regional lineaments. The NW-SE and NE-SW lineaments truncate one another, suggesting different ages for the lineament groups. A few sinistral tensional movements occur in the eastern sector of the basin.  The major folds in the Afikpo basin have NE-SW and NW-SE trends, and occur as anticlines and synclines. The basement structuring and basin framework suggest a tectonic setting in the southeastern Benue Trough resulting from the Early Cretaceous opening of the South Atlantic Ocean and interpolate movement in Africa. From the evidence currently available we may conclude that the post Santonian Afikpo basin falls within the transtenstional basin categories associated with transform faults. The regional tectonics interpreted from the radar imageries are likely hydrocarbon related structural features.
Declined Fatigue Crack Propagation Rate of a High‐Strength Steel by Electropulsing Treatment
Authors: Ben Dandan , Yang Huajie , Ma Yunrui , Wang Qiang , Tian Yanzhong , Zhang Peng , Duan Qiqiang , Zhang Zhefeng
Published: April 2019

The fatigue crack propagation behavior is a key issue for the service of engineering materials. The effect of electropulsing treatment (EPT) on the growth of fatigue crack in a high‐strength steel (AISI 4340 steel) is investigated. It is shown that the crack propagation rate could be significantly declined via high‐density EPT. The crack features of fracture surface are examined using laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). The crack deviation, local crack‐healing and bridging phenomenon are proposed to be beneficial to lower the crack propagation rate, which should be brought out by the current detour, selective Joule heating, compressive stress, and electrical breakdown phenomenon. All these EPT effects exhibit significant contributions to the improvement of fatigue properties in the widely used high‐strength steel.
Programmable Therapeutic Nanodevices with Circular Amplification of H2O2 in the Tumor Microenvironment for Synergistic Cancer Therapy
Authors: Li Jiong , Wei Zuwu , Lin Xinyi , Zheng Dongye , Wu Ming , Liu Xiaolong , Liu Jingfeng
Published: April 2019

Tumor microenvironment activated nanodevices have remarkable superiority to enhance therapeutic efficacy and minimize side effects, but their practical applications are dramatically reduced by the low abundance and heterogeneous distribution of specific stimuli at the tumor site. Herein, programmable vesicular nanodevices based on the triblock copolymer containing poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) with peroxalate esters (PO) as hydrogen peroxide‐responsive linkage (PEG‐PO‐PCL‐PO‐PEG), are developed for co‐delivery of hypoxia‐activated prodrug (AQ4N) and glucose oxidase (GOD). The obtained nanodevices (PAG) can be activated by the high level of H2O2 in tumor microenvironment to improve the permeability of membranes for glucose entrance. Afterward, the oxidation of glucose catalyzed by GOD produces amplified H2O2 amounts which in turn induce complete destruction of PAG for fast release of AQ4N and GOD. Ultimately, the PAG can exert programmable therapeutic effects from the following aspects: 1) starvation therapy by cutting off the energy supply from glucose through GOD catalysis; 2) oxidative cytotoxicity after H2O2 amplification; 3) chemotherapy of AQ4N activated by the intensified tumor hypoxia microenvironment after oxygen consumption. The stimuli amplification, controlled drug release, synergistic therapy, and corresponding mechanisms of PAG are demonstrated. Therefore, the presented work could provide significant new insights for cancer treatment.
Solution‐Free UV‐Based Direct Surface Modification of Oxide Films for Self‐Patterned Metal‐Oxide Thin‐Film Transistors
Authors: Lee Woobin , Choi Seungbeom , Kim Jaeyoung , Park Sung Kyu , Kim Yong‐Hoon
Published: April 2019

In thin‐film device fabrication, particularly using a solution process, self‐patterning is effective in reducing the fabrication steps by eliminating the conventional photolithography process. Here, solution‐free ultraviolet (UV)‐based direct surface modification is introduced for self‐patterning of solution‐processed oxide semiconductors. The direct surface modification is carried out by selectively irradiating UV light on a SiO2 film, creating regions with different surface energies. This surface energy difference induces different wetting behaviors of spin‐coated indium‐gallium‐zinc‐oxide (IGZO) precursor film, enabling the direct self‐patterning. By optimizing the surface modification conditions and the channel design, self‐patterned IGZO thin‐film transistors (TFTs) are successfully fabricated. The self‐patterned IGZO TFTs exhibit low off‐state current (<10−12 A), high on/off ratio (≈108), and low gate‐leakage level without using any channel etching process. The results show that the direct surface modification can be a good candidate for realizing self‐patterned IGZO TFTs.
Palladium‐Catalyzed Cycloisomerization of (Z)‐1‐Iodo‐1,6‐dienes to 3‐Aza‐bicyclo[4.1.0]hept‐2‐enes
Authors: Chi Xiaochen , Meng Long , Sun Xi , Liu Qing , Ai Bing , Chen Lei , Zhang Daopeng , Zhao Pingping , Dong Yunhui , Liu Hui
Published: April 2019

A Pd‐catalyzed cycloisomerization of (Z)‐1‐iodo‐1,6‐dienes was developed to construct 3‐aza‐bicyclo[4.1.0]hept‐2‐enes bearing substitutions at C1/C5. A wide array of (Z)‐1‐iodo‐1,6‐dienes could be converted to the desired compounds efficiently. On the basis of mechanistic studies, two pathways were proposed, in which compound alkyl iodide derivatives formed by reductive elimination of Csp3−Pd−I was proved to be a possible intermediate.
Desymmetrization‐Initiated Stereocontrolled Synthesis of (−)‐Kaitocephalin
Authors: Lee Wonchul
Published: April 2019

A total synthesis of (−)‐kaitocephalin (1), the first naturally isolated glutamate receptor antagonist, is described. The key steps involved the enantioselective desymmetrization of the N‐Cbz‐protected seriol 42 to install the C4 quaternary chiral center and the intramolecular mercury(II)‐mediated N‐cyclization of (Z)‐alkene 44 followed by reductive demercuration to construct the pyrrolidine ring. As proposed, the quaternary asymmetric carbon induced the stereoselective epoxidation as well as the regioselective epoxide opening to generate the C2 and C3 stereocenters.
Thionoesters as 1,2‐Dipolarophiles for [4+2] Cycloaddition with Cyclobutanones
Authors: Matsumoto Yohei , Tsuji Taro , Nakatake Daiki , Yazaki Ryo , Ohshima Takashi
Published: April 2019

The utility of thionoester as a 1,2‐dipolarophile for [4+2] cycloaddition with cyclobutanones is described. The [4+2] cycloaddition reaction provided tetrahydrothiopyran, which is found in biologically active natural products, in high yield with high diastereoselectivity by using readily available TiCl4. This synthetic method was applicable to a wide range of thionoesters and cyclobutanones. The ketone and S,O‐ketal functionalities of the product could be reduced with excellent diastereoselectivity. Furthermore, the C−O bond was transformed into a C−C bond, affording contiguous tetrasubstituted carbon centers.
A MOVEMENT IS BORN? GOOGLE ELIMINATES MANDATORY ARBITRATION
Authors: O'Casey Molly
Published: April 2019

Google has yielded to employee demands to eliminate its policy of mandatory arbitration of employment disputes.
Catalytic (3+2) Palladium‐Aminoallyl Cycloaddition with Conjugated Dienes
Authors: Trost Barry M. , Huang Zhongxing
Published: April 2019

We describe the design and application of tailored aminoallyl precursors for catalytic (3+2) cycloaddition with conjugated dienes via a Pd‐aminoallyl intermediate. The new cycloaddition reactions override the conventional (4+3) selectivity of aminoallyl cation cycloaddition through a sequence of Pd‐allyl transfer and ring closure. A variety of highly substituted or fused pyrrolidine rings were synthesized using the cycloaddition, and can further undergo [1,3] N‐to‐C rearrangement to five‐membered carbocycles with a different palladium catalyst. The utility of the (3+2) cycloaddition is also demonstrated by the preparation of various derivatives from the bicyclic pyrrolidine products.
Synthesis of Tri‐ and Difluoromethoxylated Compounds by Visible‐Light Photoredox Catalysis
Authors: Lee Johnny W. , Lee Katarzyna N. , Ngai Ming‐Yu
Published: April 2019

Trifluoromethoxy (OCF3) and difluoromethoxy (OCF2H) groups are fluorinated structural motifs that exhibit unique physicochemical characteristics. Incorporation of these substituents into organic molecules is a highly desirable approach used in medicinal chemistry and drug discovery processes to alter the properties of a parent compound. Recently, tri‐ and difluoromethyl ethers have received increasing attention and several innovative strategies to access these valuable functional groups have been developed. The focus of this Minireview is the use of visible‐light photoredox catalysis in the synthesis of tri‐ and difluoromethyl ethers. Recent photocatalytic strategies for the formation of O−CF3, C−OCF3, O−CF2H, and C−OCF2H bonds as well as other transformations leading to the construction of ORF groups are discussed herein.
Formiat‐Oxidase (FOx) aus Aspergillus oryzae: ein Katalysator für verschiedene H2O2‐abhängige biokatalytische Oxidationen
Authors: Tieves Florian , Willot Sébastien Jean‐Paul , van Schie Morten Martinus Cornelis Harald , Rauch Marine Charlène Renée , Younes Sabry Hamdy Hamed , Zhang Wuyuan , Dong JiaJia , Gomez de Santos Patricia , Robbins John Mick , Bommarius Bettina , Alcalde Miguel , Bommarius Andreas Sebastian , Hollmann Frank
Published: April 2019

Ein Vielzahl biokatalytischer Oxidationsreaktionen verwendet H2O2 als Oxidationsmittel. Oftmals erfordert allerdings die geringe Stabilität von Enzymen die Verwendung eines effizienten In‐situ‐H2O2‐Generierungssystems. In Anlehnung an die für NADH‐abhängige Reaktionen weit verbreitete Formiat‐Dehydrogenase schlagen wir hier die Verwendung einer Formiat‐Oxidase (FOx) vor, um H2O2‐abhängige enzymatische Oxidationen anzutreiben. Bereits unter nicht‐optimierten Bedingungen wurden sehr vielversprechende Katalysatorwechselzahlen bei der Kopplung von FOx mit Peroxygenasen erzielt.
High‐Quality Gasoline Directly from Syngas by Dual Metal Oxide–Zeolite (OX‐ZEO) Catalysis
Authors: Li Na , Jiao Feng , Pan Xiulian , Chen Yuxiang , Feng Jingyao , Li Gen , Bao Xinhe
Published: April 2019

Despite significant efforts towards the direct conversion of syngas into liquid fuels, the selectivity remains a challenge, particularly with regard to high‐quality gasoline with a high octane number and a low content of aromatic compounds. Herein, we show that zeolites with 1D ten‐membered‐ring (10‐MR) channel structures such as SAPO‐11 and ZSM‐22 in combination with zinc‐ and manganese‐based metal oxides (ZnaMnbOx) enable the selective synthesis of gasoline‐range hydrocarbons C5–C11 directly from syngas. The gasoline selectivity reached 76.7 % among hydrocarbons, with only 2.3 % CH4 at 20.3 % CO conversion. The ratio of isoparaffins to n‐paraffins was as high as 15, and the research octane number was estimated to be 92. Furthermore, the content of aromatic compounds in the gasoline was as low as 16 %. The composition and structure of ZnaMnbOx play an important role in determining the overall activity. This process constitutes a potential technology for the one‐step synthesis of environmentally friendly gasoline with a high octane number from a variety of carbon resources via syngas.
Dual‐Targeting Dual‐Action Platinum(IV) Platform for Enhanced Anticancer Activity and Reduced Nephrotoxicity
Authors: Babak Maria V. , Zhi Yang , Czarny Bertrand , Toh Tan Boon , Hooi Lissa , Chow Edward Kai‐Hua , Ang Wee Han , Gibson Dan , Pastorin Giorgia
Published: April 2019

A novel and highly efficient dual‐targeting platform was designed to ensure targeted in vivo delivery of dual‐action PtIV prodrugs. The dual targeting was established by liposomal encapsulation of PtIV complexes, thereby utilizing the enhanced permeability and retention (EPR) effect as the first stage of targeting to attain a high accumulation of the drug‐loaded liposomes in the tumor. After the release of the PtIV prodrug inside cancer cells, a second stage of targeting directed a portion of the PtIV prodrugs to the mitochondria. Upon intracellular reduction, these PtIV prodrugs released two bioactive molecules, acting both on the mitochondrial and on the nuclear DNA. Our PtIV system showed excellent activity in vitro and in vivo, characterized by a cytotoxicity in a low micromolar range and complete tumor remission, respectively. Notably, marked in vivo activity was accompanied by reduced kidney toxicity, highlighting the unique therapeutic potential of our novel dual‐targeting dual‐action platform.
19F Magic Angle Spinning Dynamic Nuclear Polarization Enhanced NMR Spectroscopy
Authors: Viger‐Gravel Jasmine , Avalos Claudia E. , Kubicki Dominik J. , Gajan David , Lelli Moreno , Ouari Olivier , Lesage Anne , Emsley Lyndon
Published: April 2019

The introduction of high‐frequency, high‐power microwave sources, tailored biradicals, and low‐temperature magic angle spinning (MAS) probes has led to a rapid development of hyperpolarization strategies for solids and frozen solutions, leading to large gains in NMR sensitivity. Here, we introduce a protocol for efficient hyperpolarization of 19F nuclei in MAS DNP enhanced NMR spectroscopy. We identified trifluoroethanol‐d3 as a versatile glassy matrix and show that 12 mm AMUPol (with microcrystalline KBr) provides direct 19F DNP enhancements of over 100 at 9.4 T. We applied this protocol to obtain DNP‐enhanced 19F and 19F–13C cross‐polarization (CP) spectra for an active pharmaceutical ingredient and a fluorinated mesostructured hybrid material, using incipient wetness impregnation, with enhancements of approximately 25 and 10 in the bulk solid, respectively. This strategy is a general and straightforward method for obtaining enhanced 19F MAS spectra from fluorinated materials.
An Engineered Aryl Acid Adenylation Domain with an Enlarged Substrate Binding Pocket
Authors: Ishikawa Fumihiro , Miyanaga Akimasa , Kitayama Hinano , Nakamura Shinya , Nakanishi Isao , Kudo Fumitaka , Eguchi Tadashi , Tanabe Genzoh
Published: April 2019

Adenylation (A) domains act as the gatekeepers of non‐ribosomal peptide synthetases (NRPSs), ensuring the activation and thioesterification of the correct amino acid/aryl acid building blocks. Aryl acid building blocks are most commonly observed in iron‐chelating siderophores, but are not limited to them. Very little is known about the reprogramming of aryl acid A‐domains. We show that a single asparagine‐to‐glycine mutation in an aryl acid A‐domain leads to an enzyme that tolerates a wide range of non‐native aryl acids. The engineered catalyst is capable of activating non‐native aryl acids functionalized with nitro, cyano, bromo, and iodo groups, even though no enzymatic activity of wild‐type enzyme was observed toward these substrates. Co‐crystal structures with non‐hydrolysable aryl‐AMP analogues revealed the origins of this expansion of substrate promiscuity, highlighting an enlargement of the substrate binding pocket of the enzyme. Our findings may be exploited to produce diversified aryl acid containing natural products and serve as a template for further directed evolution in combinatorial biosynthesis.
Tertiary α‐Silyl Alcohols by Diastereoselective Coupling of 1,3‐Dienes and Acylsilanes Initiated by Enantioselective Copper‐Catalyzed Borylation
Authors: Feng Jian‐Jun , Oestreich Martin
Published: April 2019

An efficient synthesis of functionalized tertiary α‐silyl alcohols by an enantio‐ and diastereoselective copper‐catalyzed three‐component coupling of 1,3‐dienes, bis(pinacolato)diboron, and acylsilanes is reported. The reaction proceeds well with different 1,3‐dienes and a broad range of aryl‐ as well as alkenyl‐ but also alkyl‐substituted acylsilanes. The target compounds are formed with high regio‐, diastereo‐, and enantioselectivity (up to 99 % ee and d.r. >20:1) and are highly versatile synthetic building blocks.
A Redox‐Confused Bismuth(I/III) Triamide with a T‐Shaped Planar Ground State
Authors: Kindervater Marcus B. , Marczenko Katherine M. , Werner‐Zwanziger Ulrike , Chitnis Saurabh S.
Published: April 2019

Reaction of a tethered triamine ligand with Bi(NMe2)3 gives a Bi triamide, for which a BiI electronic structure is shown to be most appropriate. The T‐shaped geometry at bismuth provides the first structural model for edge inversion in bismuthines and the only example of a planar geometry for pnictogen triamides. Analogous phosphorus compounds exhibit a distorted pyramidal geometry because of different Bi−N and P−N bond polarities. Although considerable BiI character is indicated for the title Bi triamide, it exhibits reactivity similar to BiIII electrophiles, and expresses either a vacant or a filled p orbital at Bi, as evidenced by coordination of either pyridine N‐oxide or W(CO)5. The product of the former shows evidence of coordination‐induced oxidation state change at bismuth.
Successful resuscitation after drowning with severe hypernatraemia and prolonged time to return of spontaneous circulation
Authors: Klitgaard T. L. , Kjaergaard B. , Staehr J. B.
Published: April 2019

We describe the successful resuscitation of a 23‐year‐old previously healthy man who had drowned. After prolonged submersion, hypothermia, severe hypernatraemia, a prolonged time to return of spontaneous circulation was possible using a combination of extracorporal life support and early continuous veno‐venous haemofiltration. This combination of clinical circumstances is rarely associated with positive outcomes, but this case demonstrates the utility of extracorporeal life support and haemofiltration in patients drowned in saltwater.
Stabilization of switched neural networks with time‐varying delay via bumpless transfer control
Authors: Liu Chao , Sun Dihua , Yang Zheng , Liu Xiaoyang , Yang Hongyu , Huang Junjian
Published: April 2019

This paper investigates the stabilization of switched neural networks with time‐varying delay. In order to overcome the drawback that the classical switching state feedback controller may generate the bumps at switching time, a new switching feedback controller which can smooth effectively the bumps is proposed. According to mode‐dependent average dwell time, new exponential stabilization results are deduced for switched neural networks under the proposed feedback controller. Based on a simple corollary, the procedures which are used to calculate the feedback control gain matrices are also obtained. Two simple numerical examples are employed to demonstrate the effectiveness of the proposed results.
Effects of 50 Hz magnetic fields on circadian rhythm control in mice
Authors: Lundberg Louise , Sienkiewicz Zenon , Anthony Daniel C. , Broom Kerry A.
Published: April 2019

Artificial light and power frequency magnetic fields are ubiquitous in the built environment. Light is a potent zeitgeber but it is unclear whether power frequency magnetic fields can influence circadian rhythm control. To study this possibility, 8–12‐week‐old male C57BL/6J mice were exposed for 30 min starting at zeitgeber time 14 (ZT14, 2 h into the dark period of the day) to 50 Hz magnetic fields at 580 μT using a pair of Helmholtz coils and/or a blue LED light at 700 lux or neither. Our experiments revealed an acute adrenal response to blue light, in terms of increased adrenal per1 gene expression, increased serum corticosterone levels, increased time spent sleeping, and decreased locomotor activity (in all cases, P < 0.0001) compared to an unexposed control group. There appeared to be no modulating effect of the magnetic fields on the response to light, and there was also no effect of the magnetic fields alone (in both cases, P > 0.05) except for a decrease in locomotor activity (P < 0.03). Gene expression of the cryptochromes cry1 and cry2 in the adrenals, liver, and hippocampus was also not affected by exposures (in all cases, P > 0.05). In conclusion, these results suggest that 50 Hz magnetic fields do not significantly affect the acute light response to a degree that can be detected in the adrenal response. Bioelectromagnetics. 2019;9999:XX–XX. © 2019 Bioelectromagnetics Society.
Antibody Binding Heterogeneity of Protein A Resins
Authors: da Silva Gonçalo F. L. , Plewka Jacek , Tscheließnig Rupert , Lichtenegger Helga , Jungbauer Alois , Dias‐Cabral Ana C. M.
Published: April 2019

Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheless, there is not enough understanding of in‐column antibody adsorption in the Protein A capture step. This work aims to investigate in situ the establishment of an antibody (trastuzumab) layer during Protein A chromatography both in terms of energetic contributions and uptake kinetics. Flow microcalorimetry is employed as a technique with an in situ operating detector, which provides an understanding of the thermodynamics of the adsorption process. In addition, the antibody uptake rate is also investigated in order to establish a correlation between its diffusion on the stationary phase and the associated thermodynamics. Two resins with different particle size, intraparticle porosity, and a Protein A ligand structure are studied: the synthetically engineered B‐domain tetrameric MabSelect SuRe and the synthetically engineered C‐domain hexameric TOYOPEARL AF‐rProtein A HC. The uptake rate follows a pore diffusion model at low equilibrium time, showing a slower diffusivity after a certain time because of the heterogeneous binding nature of these two resins. In addition, the microcalorimetric studies show that adsorption enthalpy is highly favourable at low isotherm concentrations and evolves toward an equilibrium with increasing surface concentration. These data suggest that the relationship between adsorption enthalpy and the establishment of the antibody layer in the Protein A chain is consistent with heterogeneous adsorption.
Fabrication of Self‐Propelled Micro‐ and Nanomotors Based on Janus Structures
Authors: Ye Yicheng , Luan Jiabin , Wang Ming , Chen Yongming , Wilson Daniela A. , Peng Fei , Tu Yingfeng
Published: April 2019

Delicate molecular and biological motors are tiny machines capable of achieving numerous vital tasks in biological processes. To gain a deeper understanding of their mechanism of motion, researchers from multiple backgrounds have designed and fabricated artificial micro‐ and nanomotors. These nano‐/microscale motors can self‐propel in solution by exploiting different sources of energy; thus showing tremendous potential in widespread applications. As one of the most common motor systems, Janus motors possess unique asymmetric structures and integrate different functional materials onto two sides. This review mainly focuses on the fabrication of different types of micro‐ and nanomotors based on Janus structures. Furthermore, some challenges still exist in the implementation of Janus motors in the biomedical field. With such common goals in mind, it is expected that the elaborate and multifunctional design of Janus motors will overcome their challenges in the near future.
Diindeno‐Fused Dibenzo[a,h]anthracene and Dibenzo[c,l]chrysene: Syntheses, Structural Analyses, and Properties
Authors: Boominathan Siva Senthil Kumar , Chang Kai‐Hsin , Liu Yu‐Chiao , Wang Chi‐Shin , Wu Cheng‐Feng , Chiang Ming‐Hsi , Chou Pi‐Tai , Wu Yao‐Ting
Published: April 2019

Diindeno‐fused dibenzo[a,h]anthracene 6 and diindeno‐fused dibenzo[c,l]chrysene 9 contain the key moieties 1,4‐quinodipropene (1,4‐QDP) and 2,6‐naphthoquinodipropene (2,6‐NQDP), respectively, and they both have an open‐shell singlet ground state. The latter compound exhibits a strong biradical character and interesting properties, including a low ΔET−S (2.44 kcal mol−1), a small HOMO–LUMO gap (1.06 eV), a wide photoabsorption range (250–1172 nm), and a large two‐photon absorption cross‐section (σ=1342±56 GM). This work verifies that 6 has a slightly larger HOMO–LUMO gap and ΔET−S than its helical isomer diindeno[2,1‐f:1′,2′‐j]picene (DIP), but is a much stronger two‐photon absorber, verifying the important effect of geometry on the photophysical properties.
[4]Cyclo‐N‐ethyl‐2,7‐carbazole: Synthesis, Structural, Electronic and Charge Transport Properties
Authors: Lucas Fabien , Sicard Lambert , Jeannin Olivier , Rault‐Berthelot Joëlle , Jacques Emmanuel , Quinton Cassandre , Poriel Cyril
Published: April 2019

Nanorings, which are macrocycles possessing radially directed π‐orbitals have shown fantastic development in the last ten years. Unravelling their unusual electronic properties has been one of the driving forces of this research field. However, and despite promising properties, their incorporation in organic electronic devices remains very scarce. In this work, we aim to contribute to bridge the gap between organic electronics and nanorings by reporting the synthesis, the structural and electronic properties and the incorporation in an organic field‐effect transistor (OFET) of a cyclic tetracarbazole, namely [4]cyclo‐N‐ethyl‐2,7‐carbazole ([4]C‐Et‐Cbz). The structural, photophysical and electrochemical properties have been compared to those of structurally related analogues [4]cyclo‐9,9‐diethyl‐2,7‐fluorene [4]C‐diEt‐F (with carbon bridges) and [8]‐cycloparaphenylene [8]CPP (without any bridge) in order to shed light on the impact of the bridging in nanorings. This work shows that nanorings can be used as an active layer in an OFET and provides a first benchmark in term of OFET characteristics for this type of molecules.
Prospect of Thiazole‐based γ‐Peptide Foldamers in Enamine Catalysis: Exploration of the Nitro‐Michael Addition
Authors: Aguesseau‐Kondrotas Julie , Simon Matthieu , Legrand Baptiste , Bantigniès Jean‐Louis , Kang Young Kee , Dumitrescu Dan , Van der Lee Arie , Campagne Jean‐Marc , de Figueiredo Renata Marcia , Maillard Ludovic T.
Published: April 2019

As three‐dimensional folding is prerequisite to biopolymer activity, complex functions may also be achieved through foldamer science. Because of the diversity of sizes, shapes and folding available with synthetic monomers, foldamer frameworks enable a numerous opportunities for designing new generations of catalysts. We herein demonstrate that heterocyclic γ‐peptide scaffolds represent a versatile platform for enamine catalysis. One central feature was to determine how the catalytic activity and the transfer of chiral information might be under the control of the conformational behaviours of the oligomer.
1,3‐Diene Polymerization Promoted by Half‐Sandwich Rare‐Earth‐Metal Dimethyl Complexes: Active Species Clustering and Cationization/Deactivation Processes
Authors: Hollfelder Christoph O. , Jende Lars N. , Dietrich Hans‐Martin , Eichele Klaus , Maichle‐Mössmer Cäcilia , Anwander Reiner
Published: April 2019

When activated with fluorinated borate cocatalysts the trimetallic complexes [Cp*LnMe2]3 (Ln=Y, Lu; Cp*=C5Me5) promote efficiently the formation of high‐cis polybutadiene. Respective polyisoprenes instead bear much less pronounced microstructures, but reveal crosslinked products at lower polymerization temperatures. Varying the amount of cocatalyst, the emerging active species were examined by NMR spectroscopic techniques (incl. 1H DOSY). The occurrence of donor‐solvent and thermally induced degradation products of the highly reactive precatalyst [Cp*YMe2]3 and derived catalyst species was revealed by the elucidation of methylidene clusters [Cp*3Y3Me4(CH2)(thf)2] and [Cp*6Y6Me4(CH2)4], as well as [(Cp*Y)2Me2(N(Me)2(C6H4)]n[B(C6F5)4]n, implying a multimetallic active species.
Structure‐Based Design, Synthesis, and Biological Evaluation of Imidazo[4,5‐b]pyridin‐2‐one‐Based p38 MAP Kinase Inhibitors: Part 1
Authors: Kaieda Akira , Takahashi Masashi , Fukuda Hiromi , Okamoto Rei , Morimoto Shinji , Gotoh Masayuki , Miyazaki Takahiro , Hori Yuri , Unno Satoko , Kawamoto Tomohiro , Tanaka Toshimasa , Itono Sachiko , Takagi Terufumi , Sugimoto Hiroshi , Okada Kengo , Snell Gyorgy , Bertsch Ryan , Nguyen Jasmine , Sang Bi‐Ching , Miwatashi Seiji
Published: April 2019

We identified a lead series of p38 mitogen‐activated protein kinase inhibitors using a structure‐based design strategy from high‐throughput screening of hit compound 1. X‐ray crystallography of 1 with the kinase showed an infrequent flip of the peptide bond between Met109 and Gly110, which was considered to lead to high kinase selectivity. Our structure‐based design strategy was to conduct scaffold transformation of 1 with maintenance of hydrogen bond interactions with the flipped hinge backbone of the enzyme. In accordance with this strategy, we focused on scaffold transformation to identify imidazo[4,5‐b]pyridin‐2‐one derivatives as potent inhibitors of the p38 MAP kinase. Of the compounds evaluated, 21 was found to be a potent inhibitor of the p38 MAP kinase, lipopolysaccharide‐induced tumor necrosis factor‐α (TNF‐α) production in human monocytic leukemia cells, and TNF‐α‐induced production of interleukin‐8 in human whole blood cells. Herein we describe the discovery of potent and orally bioavailable imidazo[4,5‐b]pyridin‐2‐one‐based p38 MAP kinase inhibitors that suppressed cytokine production in a human whole blood cell‐based assay.
A Tough Metal‐Coordinated Elastomer: A Fatigue‐Resistant, Notch‐Insensitive Material with an Excellent Self‐Healing Capacity
Authors: Gai Guangjie , Liu Libin , Li Cheng‐Hui , Bose Ranjita K. , Li Dong , Guo Ning , Kong Biao
Published: April 2019

Self‐healing materials can prolong device life, but their relatively weak mechanical strength limits their applications. Introducing tunable metal‐ligand interactions into self‐healing systems can improve their mechanical strength. However, applying this concept to solid elastomers is a challenge. To address this need, polyurethane‐containing metal complexes were fabricated by introduction of a pyridine‐containing ligand into polyurethane, and subsequent coordination with Fe2+. The strong reversible coordination bond provides mechanical strength and self‐healing ability. By optimizing the monomer ratio and Fe2+ content, the resulting complex possesses a very high tensile strength of 4.6 MPa at strain of around 498 % and a high Young's modulus (3.2 MPa). Importantly, the metal complex exhibits an extremely high self‐healing efficiency of approximately 96 % of tensile strength at room temperature and around 30 % at 5 °C. The complex is notch‐insensitive and the fracture energy is 76186 J/m2, which is among the highest reported values for self‐healing systems.
Drug Testing in Human‐Induced Pluripotent Stem Cell–Derived Cardiomyocytes From a Patient With Short QT Syndrome Type 1
Authors: Zhao Zhihan , Li Xin , El‐Battrawy Ibrahim , Lan Huan , Zhong Rujia , Xu Qiang , Huang Mengying , Liao Zhenxing , Lang Siegfried , Zimmermann Wolfram‐Hubertus , Cyganek Lukas , Wieland Thomas , Akin Ibrahim , Zhou Xiao‐Bo , Borggrefe Martin
Published: April 2019

Short QT syndrome (SQTS) predisposes afflicted patients to sudden cardiac death. Until now, only one drug—quinidine—has been shown to be effective in patients with SQTS type 1(SQTS1). The objective of this study was to use human‐induced pluripotent stem cell–derived cardiomyocytes (hiPSC‐CMs) from a patient with SQTS1 to search for potentially effective drugs for the treatment of SQTS1 patients. Patch clamp and single‐cell contraction measurements were employed to assess drug effects. Ivabradine, mexiletine, and ajmaline but not flecainide, ranolazine, or amiodarone prolonged the action potential duration (APD) in hiPSC‐CMs from an SQTS1 patient. Ivabradine, ajmaline, and mexiletine inhibited KCNH2 channel currents significantly, which may underlie their APD‐prolonging effects. Under proarrhythmic epinephrine stimulation in spontaneously beating SQTS1 hiPSC‐CMs, ivabradine, mexiletine, and ajmaline but not flecainide reduced the epinephrine‐induced arrhythmic events. The results demonstrate that ivabradine, ajmaline, and mexiletine may be candidate drugs for preventing tachyarrhythmias in SQTS1 patients.
Tandem Catalysis with Antagonistic Catalysts Compartmentalized in the Dispersed and Continuous Phases of a Pickering Emulsion
Authors: Vis Carolien M. , Smulders Luc C. J. , Bruijnincx Pieter C. A.
Published: April 2019

Tandem catalysis combines multiple conversion steps, catalysts, and reagents in one reaction medium, offering the potential to reduce waste and time. In this study, Pickering emulsions—emulsions stabilized by solid particles—are used as easy‐to‐prepare and bioinspired, compartmentalized reaction media for tandem catalysis. Making use of simple and inexpensive acid and base catalysts, the strategy of compartmentalization of two noncompatible catalysts in both phases of the emulsion is demonstrated by using the deacetalization–Knoevenagel condensation reaction of benzaldehyde dimethyl acetal as a probe reaction. In contrast to simple biphasic systems, which do not allow for tandem catalysis and show instantaneous quenching of the acid and base catalysts, the Pickering emulsions show efficient antagonistic tandem catalysis and give the desired product in high yield, as a result of an increased interfacial area and suppressed mutual destruction of the acid and base catalysts.
Edge/Defect Sites in α‐Co1−mFem(OH)x Nanoplates Responsible for Water Oxidation Activity
Authors: Liu Yangxing , Wang Miao , Li Yunwei , Yuan Gang , Zhang Xiangwen , Wang Qingfa
Published: April 2019

Fe‐doped transition metal (oxy)hydroxides are regarded as the most efficient oxygen evolution reaction (OER) electrocatalysts in alkaline conditions. The incorporation of Fe effectively enhances the OER activity of Co‐/Ni‐based materials, but the corresponding role of Fe in Co‐based (oxy)hydroxide materials still remains unresolved. Herein, α‐Co1−mFem(OH)x is synthesized and systematically engineered to study the effect of Fe content on the morphology, crystalline structure, electronic structure, and OER activity. As the Fe content is changed, the basic crystalline phase of α‐Co1−mFem(OH)x is consistent whereas the micromorphology changes. Much smaller and thinner nanoplates with more edge/defect sites are fabricated because of increased Fe incorporation. When the Fe content is more than 0.1, twin nanoparticles emerge at the edge/defect sites of the sister nanoplate. Additionally, the OER activity of α‐Co1−mFem(OH)x against Fe content can be plotted as a volcano curve. These data thus support a hypothesis that the edge/defect sites in α‐Co1−mFem(OH)x are responsible for the OER performance. The incorporation of Fe leads to not only the accelerated intrinsic reactivity of each active site, which is attributed to the strong electronic interaction between Co and Fe but also changes the number of edge/defect sites.
Investigation of the effect of plasma waves excitation on target normal sheath ion acceleration using fs laser‐irradiating hydrogenated structures
Authors: Torrisi L. , Cutroneo M. , Torrisi A. , Rosinski M. , Zaras‐Szydlowska A. , Parys P.
Published: April 2019

Measurements of ion acceleration in polymethylmethacrylate foils covered by a thin copper film irradiated by fs laser in target normal sheath acceleration regime are presented. The ion acceleration depends on the laser parameters, such as the pulse energy; depends on the irradiation conditions, such as the focal point position of the laser with respect to the target surface; and depends on the target properties, such as the metallic film thickness. The proton acceleration increases in the presence of the metallic film enhancing the plasma electron density, reaching about 1.6 MeV energy for a focal position on the target surface. The plasma diagnostics uses SiC detectors, absorber foils, Faraday cups, and gafchromic films. Employing p‐polarized laser light and a suitable oblique incidence, it is possible to increase the proton acceleration up to about 2.0 MeV thanks to the effects of laser absorption resonance due to plasma waves excitation.
Increased population size of fish in a lowland river following restoration of structural habitat
Authors: Lyon Jarod P. , Bird Tomas J. , Kearns Joanne , Nicol Simon , Tonkin Zeb , Todd Charles R. , O'Mahony Justin , Hackett Graeme , Raymond Scott , Lieschke Jason , Kitchingman Adrian , Bradshaw Corey J. A.
Published: April 2019

Most assessments of the effectiveness of river restoration are done at small spatial scales (<10 km) over short time frames (less than three years), potentially failing to capture large‐scale mechanisms such as completion of life‐history processes, changes to system productivity, or time lags of ecosystem responses. To test the hypothesis that populations of two species of large‐bodied, piscivorous, native fishes would increase in response to large‐scale structural habitat restoration (reintroduction of 4,450 pieces of coarse woody habitat into a 110‐km reach of the Murray River, southeastern Australia), we collected annual catch, effort, length, and tagging data over seven years for Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua) in a restored “intervention” reach and three neighboring “control” reaches. We supplemented mark–recapture data with telemetry and angler phone‐in data to assess the potentially confounding influences of movement among sampled populations, heterogeneous detection rates, and population vital rates. We applied a Bayesian hierarchical model to estimate changes in population parameters including immigration, emigration, and mortality rates. For Murray cod, we observed a threefold increase in abundance in the population within the intervention reach, while populations declined or fluctuated within the control reaches. Golden perch densities also increased twofold in the intervention reach. Our results indicate that restoring habitat heterogeneity by adding coarse woody habitats can increase the abundance of fish at a population scale in a large, lowland river. Successful restoration of poor‐quality “sink” habitats for target species relies on connectivity with high‐quality “source” habitats. We recommend that the analysis of restoration success across appropriately large spatial and temporal scales can help identify mechanisms and success rates of other restoration strategies such as restoring fish passage or delivering water for environmental outcomes.
Colonization of Northern Europe by Zygaena filipendulae (Lepidoptera)
Authors: Zagrobelny Mika , Dalsten Lene , Hille Axel
Published: April 2019

Northern and mountainous ice sheets have expanded and contracted many times due to ice ages. Consequently, temperate species have been confined to refugia during the glacial periods wherefrom they have recolonized warming northern habitats between ice ages. In this study, we compare the gene CYP405A2 between different populations of the common burnet moth Zygaena filipendulae from across the Western Palearctic region to illuminate the colonization history of this species. These data show two major clusters of Z. filipendulae populations possibly reflecting two different refugial populations during the last ice age. The two types of Z. filipendulae only co‐occur in Denmark, Sweden, and Scotland indicating that Northern Europe comprise the hybridization zone where individuals from two different refugia met after the last ice age. Bayesian phylogeographic and ecological clustering analyses show that one cluster probably derives from an Alpe Maritime refugium in Southern France with ancestral expansive tendencies to the British Isles in the west, touching Northern Europe up to Denmark and Sweden, and extending throughout Central Europe into the Balkans, the Peleponnes, and South East Europe. The second cluster encompasses East Anatolia as the source area, from where multiple independent dispersal events to Armenia, to the Alborz mountains in north‐western Iran, and to the Zagros mountains in western Iran are suggested. Consequently, the classical theory of refugia for European temperate species in the Iberian, Italian, and Balkan peninsulas does not fit with the data from Z. filipendulae populations, which instead support more Northerly, mountainous refugia.
A Dialkyl Calcium Carbene Adduct: Synthesis, Structure, and Catalytic Cross‐Dehydrocoupling of Silanes with Amines
Authors: Li Nan , Guan Bing‐Tao
Published: April 2019

Eleven neutral ligands were investigated in promoting the calcium‐catalyzed cross‐dehydrocoupling reaction between phenylsilane and diisopropylamine. Among them, N‐heterocyclic carbene (NHC) ligand IiPr2Me2 (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) displayed superior activity and selectivity. The first neutral NHC‐supported alkyl calcium complex {(IiPr2Me2)2Ca[CH(SiMe3)2]2} (4) was subsequently synthesized and characterized by NMR spectroscopy and X‐ray crystallography. Complex 4 displayed high activity and excellent chemoselectivity in the catalytic cross‐dehydrocoupling reactions between bulky amines and silanes under mild conditions. The asymmetric version was also achieved by combining Ca[CH(SiMe3)2]2 with a chiral NHC ligand, which afforded an optically active silicon stereogenic silazane in 26 % ee.
The Binary Group 4 Azide Adducts [(bpy)Ti(N3)4], [(phen)Ti(N3)4], [(bpy)2Zr(N3)4]2·bpy, and [(bpy)2Hf(N3)4]2·bpy
Authors: Saal Thomas , Deokar Piyush , Christe Karl O. , Haiges Ralf
Published: April 2019

Novel adducts of titanium, zirconium, and hafnium tetraazide with N‐donor ligands were obtained in quantitative yields from the corresponding metal fluorides [MF4] by fluoride–azide exchange with Me3SiN3 in acetonitrile solution in the presence of stoichiometric amounts of the corresponding N‐donor ligand. The polyazido adducts [(bpy)Ti(N3)4], [(phen)Ti(N3)4], [(bipy)2Zr(N3)4]2·bpy, and [(bipy)2Hf(N3)4]2·bpy were characterized by vibrational spectroscopy and single‐crystal X‐ray diffraction.
Effect of specific height on productivity and thermal efficiency of a solar still: An experimental approach under indoor environment
Authors: Jamil Basharat , Akhtar Naiem
Published: April 2019

A novel experimental approach is presented where studies have been conducted on a solar still at four specific heights in the range of 0.266–0.341 m (in steps of 0.025 m) keeping other dimensions constant. Performance of solar still is established under indoor environment to suppress meteorological factors. Uniform heat was supplied to the solar still through flat plate‐type electrical heaters. For each specific height, the performance of the solar still was evaluated at five heat fluxes (600–1000 W/m2 in steps of 100 W). Performance of solar still at different specific heights was compared in terms of operating temperatures, productivity, and efficiency. It was found that reduction in specific height enhances distillate productivity as well as thermal efficiency of the solar still due to reduction in cavity volume and an increase in average operating temperature. An increase of in daily distillate yield of 89.44% (at 600 W/m2), 56.07% (at 700 W/m2), 28.50% (at 800 W/m2), 38.60% (at 900 W/m2), and 37.38% (at 1000 W/m2) between Case 1 to Case 4 was observed. Further, between Case 1 and Case 4, the thermal efficiency increased from 27.29 to 46.18%, 32.73 to 51.06%, 36.82 to 52.17%, 41.25 to 56.79%, and 42.55 to 57.50% at 600, 700, 800, 900, and 1000 W, respectively. Results demonstrate that for a particular specific height the total daily productivity increases linearly with heat flux. Correlation for estimating thermal efficiency of solar still is proposed in terms of the aspect ratio and input power. © 2019 American Institute of Chemical Engineers Environ Prog, 38: e13227, 2019
An effective scheme to address influence maximization for opinion formation in social networks
Authors: He Qiang , Lei Zhencheng , Wang Xingwei , Huang Min , Cai Yuliang
Published: April 2019

Influence maximization for opinion formation (IMOF) is an important problem in social networks, which aims to select most influential nodes and obtains the maximal propagation of the most ideal opinions. The existing studies on the IMOF primarily concentrate on the effective selection scheme of the most influential nodes (ie, seed nodes) and the improved opinion formation models. However, there is little work describing and defining the IMOF mathematically. In this paper, we formulate the IMOF problem mathematically and propose the weighted cooperation model to compute the opinions of network nodes. To determine the most influential nodes, an effective scheme (including the score of potential nodes (SPNs) and elimination of overlapping influence (EOI)) is proposed. By using the reverse propagation process of public opinion and dynamically adjusting the influence score of each node, SPN determines the sorting of network node within the finite iterations. Moreover, to better determine the initial seed nodes, the EOI is adopted to deal with the similarity and overlapping influence among these nodes with high influence score. Finally, to evaluate the performance of SPN, the number of positive nodes with the change of seed nodes and the times of iteration by SPN is compared with three mainstream algorithms in social network data sets. Simulation results show that the proposed scheme obtains superior number of positive nodes than the comparison algorithms.