bluuebunny/crossref_metadata_2025 huggingface dataset:
PnBA/PDMAA‐Based Iron‐Loaded Micropillars Allow for Discrete Cell Adhesion and Analysis of Actuation‐Related Molecular Responses
Authors: Kojima Taisuke , Husari Ayman , Dieterle Martin Philipp , Fontaine Sarah , Prucker Oswald , Tomakidi Pascal , Rühe Jürgen
Published: February 2020

A new approach to generate magneto‐activatable microstructures for discrete cell adhesion to investigate cell mechanoresponsiveness is reported here. The system is based on poly(n‐butylacrylate) micropillar arrays, generated from prepolymers via C,H insertion chemistry and filled with magnetic iron oxide nanoparticles. The pillars' surfaces are modified such that only top faces of the pillars are cell attractive, while the pillar side walls and the area between the pillars are covered by a cell repelling hydrogel layer based on poly(N,N‐dimethyl acrylamide). Magnet stimulation leads to pillar deflection, which induces traction forces to adherent cells. Analysis of early mechanoresponse in human mesenchymal stem cells, specifically the localization of autophosphorylated focal adhesion kinase (pFAK Y397) and the co‐transcriptional activator yes‐associated protein (YAP), shows a clear redistribution of pFAK Y397 to the cell margins and an enhanced nuclear localization of YAP, following the magnetically induced mechanical actuation. The successful use of this technique shows that the generated magnetoactive posts are suitable tools to detect the onset (FAK) and maintenance (YAP) involved in stem cell mechanosensing and mechanotransduction. The platform combines selective cell adhesion with the possibility of magnetic actuation, thereby representing a promising technology to broaden the molecular understanding of cellular mechanobiology.
Dynamic Manipulation of Friction in Smart Textile Composites of Liquid‐Crystal Elastomers
Authors: Ohzono Takuya , Saed Mohand O. , Yue Youfeng , Norikane Yasuo , Terentjev Eugene M.
Published: February 2020

Smart surfaces that reversibly change the interfacial friction coefficients in response to external stimuli enable a wide range of applications, such as grips, seals, brake pads, packaging films, and fabrics. Here, a new concept of such a smart frictional system is reported: a composite film of a plain‐weave polyester textile sheet and a thermoresponsive nematic liquid crystalline elastomer (LCE). The composite is deployed with retractable microundulations of the elastomer inside each weave mesh, enabling dramatic changes of the contact interface with the opposing surface on LCE actuation, which is induced, e.g., by a change in temperature (T). At room T, the protruding viscoelastic parts of LCE in the nematic phase make contact with the opposing flat surface, resulting in a very high friction. At an elevated T (≈50 °C, isotropic phase), the undulations of LCE surface are retracted within the thickness of the textile, and the contacts are limited to small regions around overlapping textile fibers, lowering the friction dramatically. This effect is fully reversible on heating/cooling cycles. The surface undulations are spontaneous, i.e., fabricated without any lithographic or alignment techniques. The present composite opens a new way for the application of sheets/films with switchable friction enabled by stimuli‐responsive LCEs.
Intermediate Structures of Nucleation and Growth during Solidification of CuO Constrained by Graphene
Authors: Ge Mengke , Yuan Wenjuan , Zhou Lingling , Deng Ziliang , Hu Min , Li Xiang , He Jia , Xi Wei , Luo Jun
Published: February 2020

Important solid‐state information regarding solidification remains unknown, such as the intermediate structure before nucleation and precipitation pathways for each component in multicomponent materials during crystal growth. Herein, a unique intermediate structure with unequal lattice structure (the main performance is the curved lattice fringes and the unequal interplanar spacing) is observed in situ at the atomic level before CuO nucleation. The results of experiments and molecular dynamics simulations indicate that the formation of this intermediate may be due to the irregular agglomeration of Cu and O atoms. During growth, Cu–Cu layers repeatedly form at the solid–liquid interface as an intermediate state, then oxidizes, and finally forms a perfect CuO crystal. These results help to reveal the mystery of nucleation nanomaterials, especially the multicomponent materials, and elucidate microscopic crystal growth mechanisms during multicomponent materials solidification.
Probing the Ultrastructure of Spheroids and Their Uptake of Magnetic Nanoparticles by FIB–SEM
Authors: Mollo Valentina , Scognamiglio Paola , Marino Attilio , Ciofani Gianni , Santoro Francesca
Published: February 2020

Spheroids are 3D cellular systems largely adopted as model for high‐throughput screening of molecules and diagnostics tools. Furthermore, those cellular platforms also represent a model for testing new delivery carries for selective targeting. The coupling between the 3D cell environment and the nanovectors can be explored at the macroscale by optical microscopy. However, the nanomaterial‐cell interplay finds major action at the single cell and extracellular matrix level with nanoscale interactions. Electron microscopy offers the resolution to investigate those interactions; however, the specimen preparation finds major drawbacks in its operation time and preciseness. In this context, focused ion beam and scanning electron microscopy (FIB–SEM) allows for fast processing and high resolution of the cell‐nanomaterial interface. Here, in fact, a novel approach is shown to prepare large‐area 3D spheroid cell culture specimens for FIB–SEM. Sectioning procedures are explored to preserve the peculiar structure of spheroids and their interaction with magnetic nanovectors. The results pave the way for advanced investigations of 3D cellular systems with nano and micromaterials relevant to tissue engineering, bioelectronics, and diagnostics.
Light Emission from Self‐Assembled and Laser‐Crystallized Chalcogenide Metasurface
Authors: Wang Feifan , Wang Zi , Mao Dun , Chen Mingkun , Li Qiu , Kananen Thomas , Fang Dustin , Soman Anishkumar , Hu Xiaoyong , Arnold Craig B. , Gu Tingyi
Published: February 2020

Subwavelength periodic confinement can collectively and selectively enhance local light intensity and enable control over the photoinduced phase transformations at the nanometer scale. Standard nanofabrication process can result in geometrical and compositional inhomogeneities in optical phase change materials, especially chalcogenides, as those materials exhibit poor chemical and thermal stability. Here the self‐assembled planar chalcogenide nanostructured array is demonstrated with resonance‐enhanced light emission to create an all‐dielectric optical metasurface, by taking advantage of the fluid properties associated with solution‐processed films. A patterned silicon membrane serves as a template for shaping the chalcogenide metasurface structure. Solution‐processed arsenic sulfide metasurface structures are self‐assembled in the suspended 250 nm silicon membrane templates. The periodic nanostructure dramatically manifests the local light–matter interaction such as absorption of incident photons, Raman emission, and photoluminescence. Also, the thermal distribution is modified by the boundaries and thus the photothermal crystallization process, leading to the formation of anisotropic nanoemitters within the field enhancement area. This hybrid structure shows wavelength‐selective anisotropic photoluminescence, which is a characteristic behavior of the collective response of the resonant‐guided modes in a periodic nanostructure. The resonance‐enhanced Purcell effect can manifest the quantum efficiency of localized light emission.
High Responsivity and Wavelength Selectivity of GaN‐Based Resonant Cavity Photodiodes
Authors: Li Jing , Yang Chao , Liu Lei , Cao Haicheng , Lin Shan , Xi Xin , Li Xiaodong , Ma Zhanhong , Wang Kaiyou , Patanè Amalia , Zhao Lixia
Published: February 2020

The implementation of blue‐light photodiodes based on InGaN in emerging technologies, such as free‐space visible light communication (VLC), requires transformative approaches toward enhanced performance, miniaturization, and integration beyond current Si‐based technologies. This work reports on the design and realization of high‐performance InGaN‐based resonant cavity photodiodes with high‐reflectivity lateral porous GaN distributed Bragg reflectors. The well‐controlled porosification of GaN on the 2‐inch wafers enables design and fabrication of optical components, unlocking the potential of nitride semiconductors for several applications. These resonant‐cavity‐enhanced photodiodes, which have a 12 nm‐thick optically active region, exhibit a high responsivity (≈0.1 A W−1) to blue‐light even without any externally applied voltage. Furthermore, the device can operate as both an emitter and a detector of visible light at well‐defined wavelengths with spectral overlap between the electroluminescence emission and photocurrent responsivity, meeting the requirement of wavelength selectivity, thermal stability, and low‐power consumption for VLC, with potential for integration of different functionalities, that is, light emission and detection, on a single chip without additional light filters.
Interface‐Induced High Responsivity in Hybrid Graphene/GaAs Photodetector
Authors: Tian Huijun , Hu Anqi , Liu Qiaoli , He Xiaoying , Guo Xia
Published: February 2020

Photodetectors based on two‐dimensional (2D)/ three‐dimensional (3D) semiconductor heterojunction structures are emerging as appealing candidates for high‐sensitivity applications. The performances of these hybrid photodetectors are closely correlated with their current gain mechanism. Carrier recirculation is the most commonly reported mechanism. Recently, a Fermi level alignment mechanism was proposed for 2D graphene/0‐dimensional (0D) quantum dot heterostructures because of the easy Fermi level tunability of the quantum dot. In this article, an interface‐induced gain mechanism using this Fermi level alignment process is proposed and identified based on a 2D graphene/3D GaAs hybrid structure with comparative measurement configurations. Because of the high surface state density of GaAs, the photo‐excited holes tend to become trapped at the graphene/GaAs interface, which can easily lower the interface Fermi level and the Fermi level in graphene via an alignment process. When combined with the high carrier mobility characteristics of graphene, a maximum current gain of 2520 and responsivity of 1321 A W−1 are achieved in the devices. This study clarifies the role of the interface states in the gain characteristics of some 2D/3D hybrid devices, with results that are instructive for optimal device design.
Targeting Super‐Enhancers via Nanoparticle‐Facilitated BRD4 and CDK7 Inhibitors Synergistically Suppresses Pancreatic Ductal Adenocarcinoma
Authors: Huang Chen‐Song , You Xinru , Dai Chunlei , Xu Qiong‐Cong , Li Fuxi , Wang Li , Huang Xi‐Tai , Wang Jie‐Qin , Li Shi‐Jin , Gao Zhuoxing , Wu Jun , Yin Xiao‐Yu , Zhao Wei
Published: February 2020

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignant cancer with complex genomic variations, and no targetable genomic lesions have been found yet. Super‐enhancers (SEs) have been found to contribute to the continuous and robust oncogenic transcription. Here, histone H3 lysine 27 acetylation (H3K27ac) is profiled in PDAC cell lines to establish SE landscapes. Concurrently, it is also shown that PDAC is vulnerable to the perturbation of the SE complex using bromodomain‐containing protein 4 (BRD4) inhibitor, JQ1, synergized with cyclin‐dependent kinase 7 (CDK7) inhibitor, THZ1. Formulations of hydrophobic l‐phenylalanine‐poly (ester amide) nanoparticles (NPs) with high drug loading of JQ1 and THZ1 (J/T@8P4s) are further designed and developed. J/T@8P4s is assessed for size, encapsulation efficiency, morphology, drug release profiles, and drug uptake in vitro. Compared to conventional free drug formulation, the nanodelivery system dramatically reduces the hepatotoxicity while significantly enhancing the tumor inhibition effects and the bioavailability of incorporated JQ1 and THZ1 at equal doses in a Gemcitabine‐resistant PDAC patient‐derived xenograft (PDX) model. Overall, the present study demonstrates that the J/T@8P4s can be a promising therapeutic treatment against the PDAC via suppression of SE‐associated oncogenic transcription, and provides a strategy utilizing NPs to assist the drug delivery targeting SEs.
Significantly Enhanced Molecular Stacking in Ternary Bulk Heterojunctions Enabled by an Appropriate Side Group on Donor Polymer
Authors: Jiang Huanxiang , Li Xiaoming , Wang Huan , Ren Zhitao , Zheng Nan , Wang Xunchang , Li Yonghai , Chen Weichao , Yang Renqiang
Published: February 2020

Ternary strategy is a promising approach to broaden the photoresponse of polymer solar cells (PSCs) by adopting combinatory photoactive blends. However, it could lead to a more complicated situation in manipulating the bulk morphology. Achieving an ideal morphology that enhances the charge transport and light absorption simultaneously is an essential avenue to promote the device performance. Herein, two polymers with different lengths of side groups (P1 is based on phenyl side group and P2 is based on biphenyl side group) are adopted in the dual‐acceptor ternary systems to evaluate the relationship between conjugated side group and crystalline behavior in the ternary system. The P1 ternary system delivers a greatly improved power conversion efficiency (PCE) of 13.06%, which could be attributed to the intense and broad photoresponse and improved charge transport originating from the improved crystallinity. Inversely, the P2 ternary device only exhibits a poor PCE of 8.97%, where the decreased device performance could mainly be ascribed to the disturbed molecular stacking of the components originating from the overlong conjugated side group. The results demonstrate a conjugated side group could greatly determine the device performance by tuning the crystallinity of components in ternary systems.
(E)‐,(Z)‐Stereodefined α‐Chloro‐β‐tosyloxy‐α,β‐unsaturated Esters: Sequential Cross‐Couplings for (E)‐,(Z)‐Stereo Complementary Synthesis of Fully‐Substituted α,β‐Unsaturated Esters
Authors: Ashida Yuichiro , Nakata Kohei , Yoshitake Daisuke , Sato Yuka , Miyazaki Yukie , Tanabe Yoo
Published: February 2020

An (E)‐, (Z)‐stereocomplementary synthesis of fully‐substituted α,β‐unsaturated esters has been developed. The present method involves sequential cross‐coupling reactions of readily available (E)‐, (Z)‐stereodefined α‐chloro‐β‐tosyloxy‐α,β‐unsaturated esters, which were obtained by (Z)‐ and (E)‐stereocomplementary enol tosylation of methyl α‐chloro‐β‐oxoesters using novel reagents, TsCl−NaH−TMEDA(−LiCl) for Z and TsCl−iPr2NEt−N‐methylimidazole for E. The first highly chemoselective and stereoretentive Suzuki‐Miyaura cross‐couplings proceeded smoothly at the β‐TsO‐position of (E)‐ and (Z)‐α‐chloro‐β‐tosyloxy‐α,β‐unsaturated esters to afford (Z)‐ and (E)‐β‐aryl(Ar)‐α‐chloroacrylates, respectively by an accessible [Pd(OAc)2−PPh3−K2CO3] catalysis (4 examples: 89–94% yield). Subsequent highly stereoretentive Suzuki‐Miyaura cross‐couplings using the obtained (Z)‐ and (E)‐acrylates were successfully performed by a reactive [Pd(OAc)2−SPhos−K2CO3] catalysis to produce a number of (E)‐ and (Z)‐ β‐aryl(Ar)‐α‐aryl’(Ar1) and β‐aryl(Ar)‐α‐n‐hexyl acrylates (24 examples, 62–94 %). As a distinct extension, (Z)‐ and (E)‐β‐(p‐tolyl)‐α‐chloroacrylate served as appropriate partners for (E)‐ and (Z)‐stereoretentive Sonogashira, Mizoroki‐Heck, and Buchwald‐Hartwig cross‐couplings, which afforded the corresponding enyne, diene, and α‐aminoolefin types of fully‐substituted α,β‐unsaturated esters (6 examples: 52–75% yield).
Quantum Integrability of 1D Ionic Hubbard Model
Authors: Hosseinzadeh Abolfath , Jafari Seyed Akbar
Published: February 2020

The quantum integrability of the 1D ionic Hubbard model (IHM) is established using two independent numerical methods, namely i) energy level spacing statistics and ii) occupation profile of one‐particle density matrix (OPDM) eigen‐values. Both methods suggest that the 1D IHM is integrable. The calculations of energy level statistics reproduce the known results for the standard Hubbard model. Upon turning on the the ionic term, the energy level spacing distribution of this model continues to obey the Poissonian distribution. Occupation patterns as extracted from OPDM indicate that quasi‐particles are sharpened upon increasing the ionic potential. This is evidenced by a larger jump in the occupation number distribution.
Zweidimensionale Edelmetallchalkogenide und ‐phosphochalkogenide
Authors: Kempt Roman , Kuc Agnieszka , Heine Thomas
Published: February 2020

Edelmetallchalkogenide sowie deren Dichalkogenide und Phosphochalkogenide sind eine aufstrebende Klasse zweidimensionaler Materialien. Ihre Eigenschaften können durch die Lagenanzahl und Defekte über einen weiten Bereich eingestellt werden. Diese beinhalten Metall‐zu‐Halbleiter‐Übergänge, magnetische Ordnung und topologische Oberflächenzustände. Diese Materialien liegen in verschiedenen Polytypen vor, die oft ähnliche Bildungsenergien aufweisen, wodurch sie durch selektive Syntheseansätze hergestellt werden können. Sie sind herausragend in mechanischen, optischen und chemischen Sensoren, insbesondere aufgrund ihrer Stabilität gegenüber Luft und Feuchtigkeit über lange Zeiträume. In diesem Kurzaufsatz wird der gegenwärtige Fortschritt im Bereich der Edelmetallchalkogenide und deren Phosphochalkogenide zusammengefasst und die besondere strukturelle Komplexität in den Vordergrund gerückt, die ihre Anwendungen beeinflusst.
Accessing Tunable Afterglows from Highly Twisted Nonaromatic Organic AIEgens via Effective Through‐Space Conjugation
Authors: Zheng Shuyuan , Zhu Tianwen , Wang Yunzhong , Yang Tianjia , Yuan Wang Zhang
Published: February 2020

Nonaromatic, cross‐conjugated, and highly twisted luminogens consisting of acylated succinimides demonstrate aggregation‐induced emission characteristics along with tunable multicolor photoluminescence and afterglows in their single crystals. Effective through‐space conjugation among different moieties bearing n/π electrons promote the spin–orbit coupling and intersystem crossing and lead to diverse emissive clusters with concurrently rigidified conformations, thus allowing readily tunable emissions. Derived from it, the proof‐of‐concept application for advanced anti‐counterfeiting is illustrated. These results should spur the rational design of novel nonaromatic AIEgens, and moreover advance understandings of the non‐traditional intrinsic luminescence and the origin of tunable multicolor afterglows.
Selectiveortho‐Functionalization of Adamantylarenes Enabled by Dispersion and an Air‐Stable Palladium(I) Dimer
Authors: Kalvet Indrek , Deckers Kristina , Funes‐Ardoiz Ignacio , Magnin Guillaume , Sperger Theresa , Kremer Marius , Schoenebeck Franziska
Published: February 2020

Contrary to the general belief that Pd‐catalyzed cross‐coupling at sites of severe steric hindrance are disfavored, we herein show that the oxidative addition to C−Brorthoto an adamantyl group is as favored as the corresponding adamantyl‐free system due to attractive dispersion forces. This enabled the development of a fully selective arylation and alkylation of C−Brorthoto an adamantyl group, even if challenged with competing non‐hindered C−OTf or C−Cl sites. The method makes use of an air‐stable PdIdimer and enables straightforward access to diversely substituted therapeutically important adamantylarenes in 5–30 min.
Korrosion von Kulturgut: Entdeckung einer kollagenartigen Tripelhelix in der Kristallstruktur von Calciumacetat‐Hemihydrat
Authors: Bette Sebastian , Stelzner Jörg , Eggert Gerhard , Schleid Thomas , Matveeva Galina , Kolb Ute , Dinnebier Robert E.
Published: February 2020

Helikale Strukturmotive sind in der Natur omnipräsent, z. B. als DNA‐Doppelhelix oder Kollagen‐Tripelhelix. Bei letzterer ist die helikale Struktur durch Glycin bedingt, der kleinsten Aminosäure, dessen molekulare Konformation eng mit der von Essigsäure verwandt ist. In Calciumacetat‐Hemihydrat, entstanden aus der Reaktion von Essigsäure mit in der Natur allgegenwärtigem Kalk und Wasser, wurde jetzt eine kollagen‐artige Tripelhelix entdeckt. Dieses Calciumsalz wird als Ausblühung auf Molluskenschalen, Keramik oder Marmor beobachtet. In einem Modellexperiment wurde reines Calciumacetat‐Hemihydrat auf der Oberfläche eines Terrakotta‐Gefäßes auskristallisiert. Calciumacetat‐Hemihydrat kristallisiert in einer überraschend großen Elementarzelle mit einem Volumen von 11 794.5(3) Å3 bei Normalbedingungen. Acetat‐Ionen verbrücken benachbarte Calcium‐Kationen und bilden Spiralketten, die in einer Tripelhelix‐Struktur angeordnet sind.
Two‐Dimensional Noble‐Metal Chalcogenides and Phosphochalcogenides
Authors: Kempt Roman , Kuc Agnieszka , Heine Thomas
Published: February 2020

Noble‐metal chalcogenides, dichalcogenides, and phosphochalcogenides are an emerging class of two‐dimensional materials. Quantum confinement (number of layers) and defect engineering enables their properties to be tuned over a broad range, including metal‐to‐semiconductor transitions, magnetic ordering, and topological surface states. They possess various polytypes, often of similar formation energy, which can be accessed by selective synthesis approaches. They excel in mechanical, optical, and chemical sensing applications, and feature long‐term air and moisture stability. In this Minireview, we summarize the recent progress in the field of noble‐metal chalcogenides and phosphochalcogenides and highlight the structural complexity and its impact on applications.
Rapid Synthesis of Chiral 1,2‐Bisphosphine Derivatives through Copper(I)‐Catalyzed Asymmetric Conjugate Hydrophosphination
Authors: Yue Wen‐Jun , Xiao Jun‐Zhao , Zhang Shuai , Yin Liang
Published: February 2020

1,2‐Bisphosphines have been identified as one class of important and powerful chiral ligands in asymmetric catalysis with transition metals. Herein, a copper(I)‐catalyzed asymmetric hydrophosphination of α,β‐unsaturated phosphine sulfides was developed with the assistance of “soft–soft” interaction between copper(I)‐catalyst and the phosphine sulfide moiety, which afforded 1,2‐bisphosphine derivatives with diversified electronic nature and steric hindrance in high to excellent yields with high to excellent enantioselectivity. Moreover, the challenging catalytic asymmetric hydrophosphination/protonation reaction was achieved with excellent enantioselectivity. Strikingly, the dynamic kinetic resolution of racemic diarylphosphines was also successfully carried out with high to excellent diastereo‐ and enantioselectivities. Interestingly, the nucleophilic copper(I)‐diphenylphosphide species was characterized by 31P NMR spectrum and mass spectrum. At last, three products were transformed to chiral 1,2‐bisphosphines, which were employed as ligands in Rh‐catalyzed asymmetric hydrogenation of α‐amino‐α,β‐unsaturated ester. The α‐amino acid derivative was produced in high enantioselectivity, which demonstrated the utility of the present methodology.
Capturing the Monomeric (L)CuH in NHC‐Capped Cyclodextrin: Cavity‐Controlled Chemoselective Hydrosilylation of α,β‐Unsaturated Ketones
Authors: Xu Guangcan , Leloux Sébastien , Zhang Pinglu , Meijide Suárez Jorge , Zhang Yongmin , Derat Etienne , Ménand Mickaël , Bistri‐Aslanoff Olivia , Roland Sylvain , Leyssens Tom , Riant Olivier , Sollogoub Matthieu
Published: February 2020

The encapsulation of copper inside a cyclodextrin capped with an N‐heterocyclic carbene (ICyD) allowed both to catch the elusive monomeric (L)CuH and a cavity‐controlled chemoselective copper‐catalyzed hydrosilylation of α,β‐unsaturated ketones. Remarkably, (α‐ICyD)CuCl promoted the 1,2‐addition exclusively, while (β‐ICyD)CuCl produced the fully reduced product. The chemoselectivity is controlled by the size of the cavity and weak interactions between the substrate and internal C−H bonds of the cyclodextrin.
Mono‐ and penta‐nuclear self‐assembled silver(I) complexes of pyrazolyl s‐triazine ligand; synthesis, structure and antimicrobial studies
Authors: Soliman Saied M. , Albering Jörg H. , Sholkamy Essam N. , El‐Faham Ayman
Published: February 2020

The self‐assembled [Ag (PTDM)NO3] (1), [Ag (PTDM)2(H2O)]ClO4.H2O (2) and [Ag5(PTDM)4(H2O)6(ClO4)4]ClO4.2H2O (3) complexes were synthesized by the direct mixing of AgX (X = NO3¯ or ClO4¯) and 4,4′‐[6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐1,3,5‐triazine‐2,4‐diyl]dimorpholine (PTDM) ligand in water–methanol mixture. The coordination numbers of silver range from three to five. Complex 3 is a rare case in which one nitrogen atom from the same s‐triazine core of the PTDM ligand has a μ(1,1) bridging mode between Ag1 and Ag2 in the penta‐nuclear array with Ag1–N1 and Ag2–N1 distances of 2.666(4) and 2.418(3) Å, respectively. Its 3D topology has a kind of primitive dense packing derived from the α‐Po type structure. Hirshfeld analysis showed that the percentages of the O…H hydrogen bonds were 32.4, 25.4, and 42.0% in complexes 1–3, respectively. While the ligand showed no antimicrobial activity at the applicable concentration, the penta‐nuclear complex 3 had higher antibacterial (MIC = 3.7 μmol/L) and antifungal (14.6 μmol/L) potencies toward the tested microbes compared with complexes 1 and 2. Also, the killing doses of 3 were in the range of 7.3–58.5 μmol/L compared with 18.2–291.1 and 20.1–160.6 μmol/L for 1 and 2, respectively. It is clear that the higher Ag‐content in 3 could be the main reason for its higher antimicrobial activity.
Effect of silicon carbide on the mechanical and thermal properties of ethylene propylene diene monomer‐based carbon fiber composite material for heat shield application
Authors: Kumar Subham , Panda Bishnu P. , Mohanty Smita , Nayak Sanjay K.
Published: February 2020

In this article, the preparation of silicon carbide (SiC), carbon fiber (CF), and ethylene–propylene–diene monomer composite with different parts per hundred of SiC (phr) ratio (CF/SiC; 10/0, 0/10, 10/10, 10/15, 10/20) and its effect on mechanical and thermal properties have been studied. After the incorporation of SiC up to 20 phr with a stable CF (10 phr), composites demonstrated higher tensile properties up to 12.09 MPa, elongation at break (725%), modulus (3.5 MPa), and hardness (79 Shore‐A) at composition (CF10SiC20 phr). Furthermore, the density of the composites has been achieved to a maximum value of 1.081 g/cm3 at composition (CF10SiC20 phr). The synthesized composite's functional group has been analyzed using Fourier‐transform infrared spectroscopy. The thermal stability of the composites increased with the inclusion of SiC up to 20 wt% while achieving the 520°C described by thermogravimetric analysis. After gamma irradiation analysis, the mechanical properties of the composites were slightly enhanced. Thermal conductivity of the composites has been maintained up to 0.21 W/mK at CF10SiC20 phr of the composites. The morphology of silicon carbide and carbon fiber was examined using scanning electron microscopy.
Academic activism and its impact on individual‐level mobilization, sources of learning, and the future of academia in Turkey
Authors: Acar Yasemin Gülsüm , Coşkan Canan
Published: February 2020

In January 2016, academics in Turkey distributed a peace petition calling for an end to hostilities and to restart negotiations with the Kurdish movement. The Turkish government responded by opening legal cases, jailing academics, and dismissing them from universities. In the state of emergency following the July 2016 coup attempt in Turkey, the government's extended powers allowed them to fire thousands of civil servants from every branch of government, including thousands of academics. This increased the number of academics who organized to form and teach in academic collectives. The current study evaluates how politicization occurs in scholars removed from the university environment. Traditional approaches to collective action and politicization suggest that empowerment is an important catalyst in politicization and continuation of collective political engagement. With the social and political restrictions that decree law dismissals place on scholars, what is it that motivates them to politicize? The current study was conducted through semistructured interviews with nine academics who work in these collectives. Participants described their politicization in terms of previous practice, reaction to injustice, and ideals of academia and academic freedom. They further evaluated current and prospective functions and possible barriers to academic collectives. Finally, although somewhat ambivalent, participants discussed feelings of efficacy, psychosocial support, and senses of solidarity and liberation in terms of being empowered. Their perspectives provide an opportunity to understand how and where academics engage in scholar activism for an independent and free academia in the context of consolidated political oppression.
A Maltol‐Containing Ruthenium Polypyridyl Complex as a Potential Anticancer Agent
Authors: Notaro Anna , Jakubaszek Marta , Koch Severin , Rubbiani Riccardo , Dömötör Orsolya , Enyedy Éva A. , Dotou Mazzarine , Bedioui Fethi , Tharaud Mickaël , Goud Bruno , Ferrari Stefano , Alessio Enzo , Gasser Gilles
Published: February 2020

Cancer is one of the main causes of death worldwide. Chemotherapy, despite its severe side effects, is to date one of the leading strategies against cancer. Metal‐based drugs present several potential advantages when compared to organic compounds and they have gained trust from the scientific community after the approval on the market of the drug cisplatin. Recently, we reported the ruthenium complex ([Ru(DIP)2(sq)](PF6) (where DIP is 4,7‐diphenyl‐1,10‐phenantroline and sq is semiquinonate) with a remarkable potential as chemotherapeutic agent against cancer, both in vitro and in vivo. In this work, we analyse a structurally similar compound, namely [Ru(DIP)2(mal)](PF6), carrying the flavour‐enhancing agent approved by the FDA, maltol (mal). To possess an FDA approved ligand is crucial for a complex, whose mechanism of action might include ligand exchange. Herein, we describe the synthesis and characterisation of [Ru(DIP)2(mal)](PF6), its stability in solutions and under conditions that resemble the physiological ones, and its in‐depth biological investigation. Cytotoxicity tests on different cell lines in 2D model and on HeLa MultiCellular Tumour Spheroids (MCTS) demonstrated that our compound has higher activity than cisplatin, inspiring further tests. [Ru(DIP)2(mal)](PF6) was efficiently internalised by HeLa cells through a passive transport mechanism and severely affected the mitochondrial metabolism.
A Unified and Practical Method for Carbon–Heteroatom Cross‐Coupling using Nickel/Photo Dual Catalysis
Authors: Escobar Randolph A. , Johannes Jeffrey W.
Published: February 2020

While carbon–heteroatom cross‐coupling reactions have been extensively studied, many methods are specific and limited to a particular set of substrates or functional groups. Reported here is a general method that allows for C−O, C−N and C−S cross‐coupling reactions under one general set of conditions. We propose that an energy transfer pathway, in which an iridium photosensitizer produces an excited nickel(II) complex, is responsible for the key reductive elimination step that couples aryl bromides, iodides, and chlorides to 1° and 2° alcohols, amines, thiols, carbamates, and sulfonamides, and is amenable to scale up via a flow apparatus.
Playing with PtII and ZnII Coordination to Obtain Luminescent Metallomesogens
Authors: Andelescu Adelina‐Antonia , Heinrich Benoît , Spirache Maria Angela , Voirin Emilie , La Deda Massimo , Di Maio Giuseppe , Szerb Elisabeta I. , Donnio Bertrand , Costisor Otilia
Published: February 2020

Blue–green luminescent terpyridine‐containing PtII and ZnII complexes are reported. Equipped with lipophilic gallate units, which act as monodentate ancillary coordinating ligands and/or as anions, they display low‐temperature mesomorphic properties (lamello‐columnar and hexagonal mesophases for PtII and ZnII complexes, respectively). The mesomorphic properties were investigated by polarised optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X‐ray scattering of bulk materials and oriented thin films. The model of self‐assembly into the lamello‐columnar phase of the PtII complex has been described in detail. The optical properties of the complexes were investigated in the liquid and condensed liquid crystalline states, highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions for proper mesophase formation.
Towards the Sarpagine‐Ajmaline‐Macroline Family of Indole Alkaloids: Enantioselective Synthesis of an N‐Demethyl Alstolactone Diastereomer
Authors: Dagoneau Dylan , Wang Qian , Zhu Jieping
Published: February 2020

the strategy involving the use of functionalized tetrahydro‐6H‐cycloocta[b]indol‐6‐one is reported as a key intermediate for synthesis of members of the sarpagine‐ajmaline‐macroline family of monoterpene indole alkaloids. The desired tricycle was synthesized through the following key steps: 1) Evans’ syn‐selective aldolization; 2) Liebeskind–Srogl cross‐coupling using the phenylthiol ester of 3‐chloropropanoic acid as a surrogate of acrylic thioester for the synthesis of 2,3‐disubstituted indoles; and 3) ring‐closing metathesis (RCM) for the formation of the eight‐membered ring. An N‐allylation followed by intramolecular 1,4‐addition was planned for synthesis of the vobasine class of natural products. However, attempted cyclizations under a diverse set of conditions involving anionic, radical, and organopalladium/organonickel species failed to produce the bridged ring system. On the other hand, esterification of the pendant primary alcohol function with acetoacetic acid, followed by intramolecular Michael addition, afforded the desired tetracycle with excellent diastereoselectivity. Subsequent functional group manipulation and transannular cyclization of the amino alcohol afforded the N(1)‐demethyl‐3,5‐diepi‐alstolactone. We believe that the same synthetic route would afford the alstolactone should the amino alcohol with appropriate stereochemistry be used as the starting material.
Differences in temperature response of phenological development among diverse Ethiopian sorghum genotypes are linked to racial grouping and agroecological adaptation
Authors: Tirfessa Alemu , McLean Greg , Mace Emma , van Oosterom Erik , Jordan David , Hammer Graeme
Published: February 2020

Sorghum [Sorghum bicolor (L.) Moench] is an important dryland crop in the semiarid tropics, and temperature and photoperiod are the main environmental factors affecting its phenology and thus adaptation. The objectives of this study were to quantify the response of development rate to temperature and photoperiod for 19 diverse Ethiopian sorghum genotypes, and to determine if differences in these responses could be linked to racial grouping or agroecological adaptation. The genotypes, representing four major sorghum races and adaptation to four agroecological zones, were sown on 12 dates at two locations in Ethiopia with contrasting altitude. This created a range in photoperiod and temperatures relevant to Ethiopian conditions. Days from emergence to flag leaf appearance, anthesis, and maturity were recorded. A predictive phenology modeling framework was used to fit the effects of photoperiod and temperature on the rate of development for both the pre‐ and post‐anthesis periods. Results indicated that the pre‐anthesis development rate was independent of photoperiod for the range tested. This result differed from West African germplasm and likely reflects differences in agroecological adaptation and racial background. Significant genotypic differences were observed for the base temperature (0–9.8 °C) and for the optimum rate of development (0.011–0.022 d–1, with low value indicating late anthesis), with differences related to agroecology and racial type. Post‐anthesis differences in the temperature response were minor. The observed differences in pre‐anthesis base temperature can positively affect sorghum breeding programs globally, especially in temperate regions where suitability for early spring plantings is often restricted by low temperatures.
FPGA‐based system for effective IQ imbalance mitigation of RF power amplifiers
Authors: Nuñez Perez Jose Cruz , Juarez Cazares Sergio Alberto , Galaviz Aguilar Jose Alejandro , Sandoval Ibarra Yuma , Perez Pinal Francisco Javier , Tlelo Cuautle Esteban
Published: February 2020

To provide an adequate signal integrity to a power amplifier (PA), we propose a digital system for the degradation at the transmitter path, and it is implemented on a field‐programmable gate array (FPGA) board. The proposed system offers the following features: A
‐ary quadrature amplitude modulation (QAM) digital signal generation and in‐phase/quadrature (IQ) imbalance mitigation, and by default, it performs as a predistortion model extraction from PA‐measured data. The simulations and tests provided are performed to effectively verify the PA linearity by using 256‐QAM signals. The nonlinearities are predicted as a reliable solution for linearizing the PA from measurements of AM/AM and AM/PM conversion curves. The performance is evaluated in terms of linearity, computation complexity, and FPGA hardware synthesis according to a dependability compliance of digital signal processing. Finally, the model is validated with input/output data observations to linearize the model with a fitting normalized mean squared error (NMSE) of around
 dB, a spurious free dynamic range of 40 dBm, and an adjacent channel power ratio reduction by
 dBm, for a class‐AB broadband radio frequency PA GaN HEMT of 10 W working at 2.34 GHz.
Direct Copper‐Catalyzed C‐H Monofluoroalkylation of Benzoxazoles with 1‐Fluoro‐1‐haloalkanes
Authors: Li Wei , Varenikov Andrii , Gandelman Mark
Published: February 2020

The first example of direct C–H bond monofluoroalkylation with 1‐fluoro‐1‐haloalkanes with no adjacent functional groups and with β‐hydrogens has been developed. This transformation offers a straightforward route for the synthesis of a series of monofluoroalkylated benzoxazoles.
A Novel Self‐protection Hydroquinone Electrochemical Sensor Based on Thermo‐sensitive Triblock Polymer PS‐PNIPAm‐PS
Authors: Zhao Pengcheng , Ni Meijun , Chen Chao , Wang Chenxi , Yang Pingping , Wang Xiahui , Li Chunyan , Xie Yixi , Fei Junjie
Published: February 2020

A novel self‐protection sensor was successfully constructed based on an interesting thermo‐sensitive triblock polymer PS‐PNIPAm‐PS. At low temperatures (<24 °C), the analyte was able to undergo the redox process at the modified electrode. However, the polymer shrunk and accumulated at high temperatures (>30 °C), which dramatically increased the electron transfer resistance (Rct) of the modified electrode and consequently blocked the occurrence of the redox reaction to protect the electrode from high temperatures and enhance its stability. Under optimized conditions, the proposed sensor showed a good detection range for hydroquinone (6×10−7 to 2.35×10−3 M) and a low LOD (490 nM). The sensor was also successfully applied for detecting hydroquinone in real samples. The present work may provide a novel method for electrode protection, high‐temperature alarm, high‐temperature protection of batteries and new sensors production.
A simple method for the design of thermal energy storage systems
Authors: Campos‐Celador Álvaro , Diarce Gonzalo , Larrinaga Pello , García‐Romero Ane Miren
Published: February 2020

One of the key factors that currently limits the commercial deployment of thermal energy storage (TES) systems is their complex design procedure, especially in the case of latent heat TES systems. Design procedures should address both the specificities of the TES system under consideration and those of the application to be integrated within. This article presents a fast and easy to apply methodology for the selection of the design of TES systems suitable for both direct and indirect contact sensible and latent TES. The methodology is divided into four steps covering: (a) description of the thermal process or application, (b) definition of the specifications to be met by the TES system, (c) characterization of the specific TES system under consideration and (d) the determination of the TES design. This methodology needs as major inputs the operation conditions of the energy system where the TES system will be integrated, that is, temperatures and mass‐flow; as well as the charging and discharging time performed by the TES system under different conditions. The latter can be generally deduced from the Fourier number, which can be obtained both theoretically (ie, by simulation) or empirically from the analysis of the TES technology under consideration. The methodology is then applied to a 10 kW residential cogeneration application considering two TES technologies. One consists of a direct‐contact hot water storage tank and the other, of an indirect‐contact plate‐based latent heat TES system developed by the authors. The resulting volume needs for the hot water storage tank is approximately twice the volume of the latent heat TES system, respectively, 5.97 and 2.96 m3. The presented methodology eases the design process of TES systems and decreases the amount of time needed to size them from days/hours to minutes.
Tiefgreifende Hangdeformation am südlichen Heinzenberg
Authors: Osten Julian , Küppers Jan , Dufresne Anja , Huwiler Andreas , Amann Florian
Published: February 2020

Geotechnical assessment of the refilling of the Lüschersee

A mass movement of several m/year towards the Nolla stream was detected at the southern Heinzenberg (Grisons, Switzerland) in the 19th century. Debris flows originating from the upper stream valley reached the Hinterrhein valley at irregular intervals, creating temporary dams, which raised the river > 10 m above normal levels. Since 1870, comprehensive mitigation strategies, including torrent control and drainage of the 3‐ha Lüschersee lake situated in the landslide area, have reduced the deformation velocity to approx. 4.3 cm/year and prevented further debris flows.

Whether draining of the Lüschersee has influenced the slope deformation was debated back then and has not been conclusively resolved till this day. A potential use of the lake to store water for the local ski area makes the topic current.

The integration of geological data with the results of numerical simulations shows that both the mechanical effect of the artificially raised riverbed and the subsequently reduced erosion have a positive influence on the slope, although the effects of changing the hydrogeological situation by refilling the Lüschersee remain uncertain. Therefore, the decision on refilling is dependent on a successful test filling accompanied by permanent GPS measurements.
Kava drinking in traditional settings: Towards understanding effects on cognitive function
Authors: Aporosa Apo S. , Atkins Martin , Brunton Richard
Published: February 2020

Background

Kava drinking is a tradition among Pacific Island people, although growing in popularity with other ethnicities. However, drinking substantial quantities of kava has raised concerns regarding physical manifestations of slow response and lack of precision in bodily control. These impairments can have significant consequences when after consuming large volumes of kava an individual makes a choice to drive.

Aims

The objective of this study was to measure selected cognitive functions following high traditionally consumed kava volumes (greater than 2,000 mg of kavalactones) aimed at identifying potential risks for kava drink‐drivers.

Methods

The reaction and divided attention of 20 control participants was assessed against 20 active kava‐drinking participants during and following a 6‐hr kava session in a “naturalised” setting. Assessment measures were drawn from Vienna Test System—Traffic's test battery.

Results/Outcomes

Results showed no statistical significant difference between control and active participants at any measurement point over a 6‐hr testing period regardless that the movements and speech of the active participants were observed to slow as the test session and kava consumption progressed.

Conclusion

Inconsistencies between test results and observations during testing and by road policing officers demonstrate an urgent need for more research in this field.
Menstrual and reproductive characteristics and breast cancer risk by hormone receptor status and ethnicity: The Breast Cancer Etiology in Minorities study
Authors: John Esther M. , Phipps Amanda I. , Hines Lisa M. , Koo Jocelyn , Ingles Sue A. , Baumgartner Kathy B. , Slattery Martha L. , Wu Anna H.
Published: February 2020

We pooled multiethnic data from four population‐based studies and examined associations of menstrual and reproductive characteristics with breast cancer (BC) risk by tumor hormone receptor (HR) status [defined by estrogen receptor (ER) and progesterone receptor (PR)]. We estimated odds ratios and 95% confidence intervals using multivariable logistic regression, stratified by age (<50, ≥50 years) and ethnicity, for 5,186 HR+ (ER+ or PR+) cases, 1,365 HR− (ER− and PR−) cases and 7,480 controls. For HR+ BC, later menarche and earlier menopause were associated with lower risk in non‐Hispanic whites (NHWs) and Hispanics, and higher parity and longer breast‐feeding were associated with lower risk in Hispanics and Asian Americans, and suggestively in NHWs. Positive associations with later first full‐term pregnancy (FTP), longer interval between menarche and first FTP and shorter time since last FTP were limited to younger Hispanics and Asian Americans. Except for nulliparity, reproductive characteristics were not associated with risk in African Americans. For HR− BC, lower risk was associated with later menarche, except in African Americans and older Asian Americans and with longer breast‐feeding in Hispanics and Asian Americans only. In younger African Americans, HR− BC risk associated with higher parity (≥3 vs. 1 FTP) was increased fourfold in women who never breast‐fed, but not in those with a breast‐feeding history, suggesting that breast‐feeding may mitigate the adverse effect of higher parity in younger African American women. Further work needs to evaluate why menstrual and reproductive risk factors vary in importance according to age and ethnicity.