bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractNonaromatic, 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

AbstractContrary 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

AbstractHelikale 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

AbstractNoble‐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

Abstract1,2‐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

AbstractThe 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.
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

AbstractIn 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

AbstractIn 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

AbstractCancer 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

AbstractWhile 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

AbstractBlue–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

Abstractthe 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

AbstractSorghum [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

SummaryTo 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.
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

AbstractA 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

AbstractOne 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

AbstractGeotechnical assessment of the refilling of the LüscherseeA 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.