bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Laser Melting to Manufacture “In Situ” Metal Matrix Composites: A Review
Authors: Dadbakhsh Sasan , Mertens Raya , Hao Liang , Van Humbeeck Jan , Kruth Jean‐Pierre
Published: January 2019

After a brief introduction on selective laser melting (SLM) and “ex situ” manufacture of metal matrix composites (MMCs), this paper reviews the capacities and benefits of SLM to activate and control various “in situ” reactions during fabrication of 3D parts. It introduces several systems (such as Al/Fe2O3, AlSi10Mg/SiC, Al/ZnO, Ti/C, Ti/SiC, Ti/Si3N4, Ti/Mo2C, Fe/SiC, etc.) used to manufacture Al‐based, Ti‐based, and steel‐based “in situ” MMCs. Then, it illustrates the novel microstructural characteristics of these SLM‐made “in situ” MMCs for different cases, as they may appear from nano‐particles to nano‐whiskers and dendritic reinforcements homogeneously distributed in a metal matrix. It also focuses on SLM associated “in situ” mechanisms, explaining how an “in situ” reaction propagates based on “decomposition, diffusion, and reformation” and how the growth mechanisms turn into different morphologies such as rounded particles, whiskers, or polygonal block shapes. The influence of various SLM parameters (such as energy density, laser power/speed, powder layer thickness, and the size of initial powder particles) and the SLM “in situ” challenges are also discussed.
Patterning Smectic Liquid Crystals for OFETs at Low Temperature
Authors: Zou Cheng , Yanahashi Naoto , Wu Yuchen , Wang Jingxia , Zhang Cuihong , Xiong Guirong , Yang Huai , Jiang Lei , Ikeda Tomiki
Published: January 2019

The preparation of regular microstructures with liquid crystalline materials for organic field effect transistors (OFETs) is an attractive but challenging issue. However, it is usually limited by the difficulty of forming large‐area single crystals aligned in a desirable direction. Herein, several terthiophene (TTP) smectic liquid crystals such as 8‐TTP‐8 and 12‐TTP‐11OH are patterned into highly crystalline microstripes by a sandwich system through a dewetting method. Morphology and orientation of the microstripes strongly depend on preparation temperature. Microstripes prepared below crystalline temperature are uniform, well‐ordered, and show high field effect transistor (FET) mobility. Meanwhile, π–π stacking direction of the TTP backbone is perpendicular to the microstripe and the molecules stack in layer structure, standing up on the SiO2/Si substrate, which would provide an effective pathway for p‐type charge transport. However, higher preparation temperatures at liquid crystalline or isotropic liquid range induce many defects in the crystal formation process and cause incline of the unit cell, thus leading to a sharp decrease in FET mobility. A possible mechanism of molecular stacking at different temperature range is proposed. This strategy promised to provide a new opportunity for the high cost‐efficiency fabrication of OFETs.
Hierarchical Metamaterials for Multispectral Camouflage of Infrared and Microwaves
Authors: Kim Taehwan , Bae Ji‐Yeul , Lee Namkyu , Cho Hyung Hee
Published: January 2019

Camouflage is an emerging application of metamaterials owing to their exotic electromagnetic radiative properties. Based on the use of a selective emitter and an absorber as the metamaterials, most reported articles have suggested the use of single‐band camouflage, however, multispectral camouflage is a challenging issue owing to a difference of several orders of magnitude in the unit cell structure. Herein, hierarchical metamaterials (HMMs) for multispectral signal control when dissipating the absorbed energy of microwaves through the selective emission of infrared (IR) waves from the unit cell structure of the HMM are demonstrated. Integrating an IR selective emitter (IRE) with a microwave selective absorber, multispectral signal control with the large‐sized unit cell structures of up to 10 cm are realized. With an IRE, the emissive power from the HMM toward 5–8 µm is 1570% higher than the Au surface, which is preventing the occurrence of thermal instability. Furthermore, we determine that the signature levels of targeted IR waves (8–12 µm) and microwaves (2.5–3.8 cm) are reduced by up to 95% and 99%, respectively, when applying the HMM.
Carbonized‐MOF as a Sulfur Host for Aluminum–Sulfur Batteries with Enhanced Capacity and Cycling Life
Authors: Guo Yue , Jin Hongchang , Qi Zhikai , Hu Zhiqiu , Ji Hengxing , Wan Li‐Jun
Published: January 2019

The rechargeable aluminum–sulfur (Al–S) battery is a promising next generation electrochemical energy storage system owing to its high theoretical capacity of 1672 mAh g−1 and in combining low‐cost and naturally abundant elements, Al and S. However, to date, its poor reversibility and low lifespan have limited its practical application. In this paper, a composite cathode is reported for Al–S batteries based on S anchored on a carbonized HKUST‐1 matrix (S@HKUST‐1‐C). The S@HKUST‐1‐C composite maintains a reversible capacity of 600 mAh g−1 at the 75th cycle and a reversible capacity of 460 mAh g−1 at the 500th cycle under a current density of 1 A g−1, with a Coulombic efficiency of around 95%. X‐ray diffraction and Auger spectrum results reveal that the Cu in HKUST‐1 forms S–Cu ionic clusters. This serves to facilitate the electrochemical reaction and improve the reversibility of S during charge/discharge. Additionally, Cu increases the electron conductivity at the carbon matrix/S interface to significantly decrease the kinetic barrier for the conversion of sulfur species during battery operation.
Slow Hot‐Carrier Cooling in Halide Perovskites: Prospects for Hot‐Carrier Solar Cells
Authors: Li Mingjie , Fu Jianhui , Xu Qiang , Sum Tze Chien
Published: January 2019

Rapid hot‐carrier cooling is a major loss channel in solar cells. Thermodynamic calculations reveal a 66% solar conversion efficiency for single junction cells (under 1 sun illumination) if these hot carriers are harvested before cooling to the lattice temperature. A reduced hot‐carrier cooling rate for efficient extraction is a key enabler to this disruptive technology. Recently, halide perovskites emerge as promising candidates with favorable hot‐carrier properties: slow hot‐carrier cooling lifetimes several orders of magnitude longer than conventional solar cell absorbers, long‐range hot‐carrier transport (up to ≈600 nm), and highly efficient hot‐carrier extraction (up to ≈83%). This review presents the developmental milestones, distills the complex photophysical findings, and highlights the challenges and opportunities in this emerging field. A developmental toolbox for engineering the slow hot‐carrier cooling properties in halide perovskites and prospects for perovskite hot‐carrier solar cells are also discussed.
Perovskite Photovoltaics: The Significant Role of Ligands in Film Formation, Passivation, and Stability
Authors: Zhang Hong , Nazeeruddin Mohammad Khaja , Choy Wallace C. H.
Published: January 2019

Due to their outstanding optoelectronic properties, metal halide perovskites have been intensively studied in recent years. The latest certificated efficiency of 23.3% recently achieved in perovskite solar cells (PVSCs) enables them to be used as a very promising candidate for next‐generation photovoltaics. The morphology, defect density, and water resistance of perovskite films have an enormous impact on the performance and stability of PVSCs. Ligands, with coordinating capability, have been widely developed to improve the quality and stability of perovskite materials significantly. In the first section of this review, the role of ligands in fabricating perovskite films by different methods (one‐step, two‐step, and postdeposition treatment) is discussed. In the second section, the progress on ligand‐passivated perovskites via post‐treatment, in situ passivation during perovskite formation, and modifying the substrates before perovskite formation is reviewed. In the third section, a discussion of ligand‐stabilized perovskite films from the perspectives of crystal crosslinking, dimensionality engineering, and interfacial modification is presented. Finally, a summary and an outlook are given.
Interfacial Modification in Organic and Perovskite Solar Cells
Authors: Bi Shiqing , Leng Xuanye , Li Yanxun , Zheng Zhong , Zhang Xuning , Zhang Yuan , Zhou Huiqiong
Published: January 2019

Organic bulk heterojunction solar cells (OSCs) and hybrid halide perovskite solar cells (PSCs) are two promising photovoltaic techniques for next‐generation energy conversion devices. The rapid increase in the power conversion efficiency (PCE) in OSCs and PSCs has profited from synergetic progresses in rational material synthesis for photoactive layers, device processing, and interface engineering. Interface properties in these two types of devices play a critical role in dictating the processes of charge extraction, surface trap passivation, and interfacial recombination. Therefore, there have been great efforts directed to improving the solar cell performance and device stability in terms of interface modification. Here, recent progress in interfacial doping with biopolymers and ionic salts to modulate the cathode interface properties in OSCs is reviewed. For the anode interface modification, recent strategies of improving the surface properties in widely used PEDOT:PSS for narrowband OSCs or replacing it by novel organic conjugated materials will be touched upon. Several recent approaches are also in focus to deal with interfacial traps and surface passivation in emerging PSCs. Finally, the current challenges and possible directions for the efforts toward further boosts of PCEs and stability via interface engineering are discussed.
A New Class of Materials: Sequence‐Defined Macromolecules and Their Emerging Applications
Authors: Meier Michael A. R. , Barner‐Kowollik Christopher
Published: January 2019

Emerging applications of a new class of materials, sequence‐defined macromolecules, are explored. Such molecularly highly defined macromolecules require stringent synthesis and purification procedures, yet offer unprecedented application possibilities. The first examples of molecular data storage and related technologies are already starting to emerge today. From a more fundamental point of view, such macromolecules offer a unique opportunity to determine quantitative structure–property relationships (QSPR), which critically aids in designing materials with applications ranging from catalysis to artificial enzymes.
Stretchable Conductive Polymers and Composites Based on PEDOT and PEDOT:PSS
Authors: Kayser Laure V. , Lipomi Darren J.
Published: January 2019

The conductive polymer poly(3,4‐ethylenedioxythiophene) (PEDOT), and especially its complex with poly(styrene sulfonate) (PEDOT:PSS), is perhaps the most well‐known example of an organic conductor. It is highly conductive, largely transmissive to light, processible in water, and highly flexible. Much recent work on this ubiquitous material has been devoted to increasing its deformability beyond flexibility—a characteristic possessed by any material that is sufficiently thin—toward stretchability, a characteristic that requires engineering of the structure at the molecular‐ or nanoscale. Stretchability is the enabling characteristic of a range of applications envisioned for PEDOT in energy and healthcare, such as wearable, implantable, and large‐area electronic devices. High degrees of mechanical deformability allow intimate contact with biological tissues and solution‐processable printing techniques (e.g., roll‐to‐roll printing). PEDOT:PSS, however, is only stretchable up to around 10%. Here, the strategies that have been reported to enhance the stretchability of conductive polymers and composites based on PEDOT and PEDOT:PSS are highlighted. These strategies include blending with plasticizers or polymers, deposition on elastomers, formation of fibers and gels, and the use of intrinsically stretchable scaffolds for the polymerization of PEDOT.
Linear and Nonlinear Optical Properties of Few‐Layer Exfoliated SnSe Nanosheets
Authors: Ye Yuting , Xian Yuehui , Cai Jiawen , Lu Kaicheng , Liu Zhengzheng , Shi Tongchao , Du Juan , Leng Yuxin , Wei Rongfei , Wang Weiqi , Liu Xiaofeng , Bi Gang , Qiu Jianrong
Published: January 2019

Monochalcogenides of group IV elements have been considered as phosphorene analogs due to their similar crystal and electronic structure. Here, few‐layer SnSe nanosheets are synthesized by a sonication‐assisted liquid phase exfoliation process and their linear and nonlinear optical properties are examined. The as‐exfoliated few‐layer (FL) SnSe demonstrates layer thickness from 2 to 10 nm and lateral size of 150 nm with high crystallinity. Optical measurement confirms the layer‐number dependent bandgap, which is also corroborated by first‐principle calculation. In addition, the FL SnSe shows a transition from saturable absorption to reverse saturable absorption with the increase of pumping power, and the nonlinear absorption is characterized by an ultrafast response time of picosecond scale. The nonlinear optical response in FL SnSe could be explained by defect‐involved recombination of photogenerated carriers as well as the Auger scattering process, which is further enhanced by structural two‐dimensionality.
Ultrathin Metal Films as the Transparent Electrode in ITO‐Free Organic Optoelectronic Devices
Authors: Bi Yan‐Gang , Liu Yue‐Feng , Zhang Xu‐Lin , Yin Da , Wang Wen‐Quan , Feng Jing , Sun Hong‐Bo
Published: January 2019

Transparent conductive electrodes, as transmission windows of photons and electrons, play important roles in high‐performance organic optoelectronic devices. The replacement of widely used indium tin oxide (ITO) electrodes has been attempted due to the increasing cost and intrinsically brittle characteristics of ITO. Ultrathin metal films, with excellent optoelectrical features, high flexibility, and sufficient mechanical stability, have been considered a potential candidate for the use as transparent conductive electrodes. However, ultrathin metal films follow the Volmer–Weber mechanism, resulting in a rough and discontinuous morphology with poor optoelectrical properties due to the bad adhesion to substrates. This review summarizes the progress in strategies for preparing ultrathin and ultrasmooth metal films with superior transmittance and conductivity by successfully suppressing the Volmer–Weber mechanism. The electrical and optical performances of the ultrathin metal films based on improved nucleation processes, as well as applications in ITO‐free organic optoelectronic devices, are also described and discussed in detail.
Directional Modulation of Fluorescence by Nanowire‐Based Optical Traveling Wave Antennas
Authors: Wang Yilin , Li Chao , Duan Gaoyan , Wang Lulu , Yu Li
Published: January 2019

Plasmonic optical antennas can direct light from quantum emitters and improve nanophotonics device efficiency. In this study, composite structures with V‐shaped Ag nanowires (V‐Ag NWs) and quantum dots (QDs) are designed and fabricated. V‐Ag NWs serving as optical traveling wave antennas (TWAs) are employed for QD fluorescence emission direction control. The modulated emission directionality is achieved up to 11.8 dB, and the azimuthal angle half‐power bandwidth is as narrow as 35°. The azimuthal radiation is effectively tuned from 0° to over 40° by changing the bending angles of the structures. Finite‐difference time‐domain and Green's function methods are used to analyze the far field radiation patterns that are in good agreement with the experiment measurements. TWAs are easy to fabricate and integrate with optical waveguide. Thus, they are excellent tools for realizing unidirectional fluorescence emission and are potentially applicable in integrated plasmonics and nanophotonics devices.
Narrow‐Band Green‐Emitting Sr2MgAl22O36:Mn2+ Phosphors with Superior Thermal Stability and Wide Color Gamut for Backlighting Display Applications
Authors: Zhu Yingli , Liang Yujun , Liu Shiqi , Li Haoran , Chen Jiahui
Published: January 2019

The narrow‐band emitting phosphors have been extensively investigated in recent years, with the expectation that a wide color gamut of phosphor‐converted backlighting device could be fabricated. Due to the weak electric–phonon interaction and low structural relaxation caused by the high rigid crystal structure and symmetric coordination environment, Sr2MgAl22O36:Mn2+ (SMAO:Mn2+) shows a narrow full‐width at half‐maximum of 26 nm, a high color purity of 81.5%, and a low thermal quenching (82% at 473 K of the initial intensity at 298 K). Using K2SiF6:Mn4+ as the red phosphor, SMAO:Mn2+ as the green one, and GaN‐based chip as the blue component, the white light‐emitting diode exhibits a National Television Standard Committee value of 127%. All the results demonstrate that the SMAO:Mn2+ phosphor has a promising application in the field of advanced wide‐color‐gamut backlight display, and the establishment of the relationships between the narrow‐band emission and crystal structure can also be applied to design other novel narrow‐band phosphors for backlighting technologies.
Ternary Exciplexes for High Efficiency Organic Light‐Emitting Diodes by Self‐Energy Transfer
Authors: Jeon Sang Kyu , Jang Ho Jin , Lee Jun Yeob
Published: January 2019

Ternary exciplexes with an external quantum efficiency of 17.5% are developed by mixing a p‐type donor material, an n‐type acceptor material, and a donor–acceptor type material together. In the ternary mixture, the n‐type donor generates exciplexes with the p‐type donor and the donor–acceptor type material at the same time. Two different exciplexes with dissimilar emission wavelengths are formed and the emission of the high‐energy exciplex is transferred to the low‐energy exciplex by energy transfer. The high‐energy exciplex and low‐energy exciplex work as a host and dopant in the emitting layer, respectively. The internal exciplex‐to‐exciplex energy transfer induces efficient emission of the low‐energy exciplex, resulting in high efficiency of 17.5% in the exciplex device. This is the first demonstration of self‐energy transfer in the exciplex and the efficiency of the ternary exciplexes is one of the best quantum efficiencies achieved in the exciplex organic light‐emitting diodes.
Discovery of New Narrow‐Band Phosphors with the UCr4C4‐Related Type Structure by Alkali Cation Effect
Authors: Zhao Ming , Zhou Yayun , Molokeev Maxim S. , Zhang Qinyuan , Liu Quanlin , Xia Zhiguo
Published: January 2019

Narrow‐band luminescence materials used in white light‐emitting diodes (WLEDs) have demonstrated a great potential to increase the maximum accessible color gamut, improve the color rendition, or enhance the visual luminous efficacy for illumination and display devices. So far, the discovery of narrow‐band rare earth doped phosphors for emerging applications remains challenging owing to the limited systems in use and the broadening effect of 4f–5d transition. Here, two narrow‐band cyan‐emitting phosphors with the UCr4C4‐related type structure, RbNa2K(Li3SiO4)4:Eu2+ (RNKLSO:Eu2+) and CsNa2K(Li3SiO4)4:Eu2+ (CNKLSO:Eu2+), are reported. The narrow‐band emission results from the highly condensed network and a cube‐like site for the activator (Eu2+). The emission peak assignments are investigated, and the variations of luminescence behavior with compositional changes of alkali cations are elaborated in detail. RNKLSO:8% Eu2+ (95%@250 °C of the integrated emission intensity at 25 °C) shows better thermal stability than that of CNKLSO:8% Eu2+ (79%@250 °C), which can be explained by the thermally activated crossover process represented in the configurational coordinate diagram. The optical properties of the as‐fabricated WLEDs are studied and demonstrate potential with tunable properties for the full spectrum phosphor‐converted LEDs. These findings in UCr4C4‐type phases help shedding light on new avenues for fabricating new and totally unexpected narrow‐emitting phosphors with versatile applications.
A Copper (II) Acetate Mediated Oxidative‐Coupling of Styrenes and Ethers Through an Unactivated C(sp3)−H Bond Functionalization
Authors: Yan Zhan , Wang Nai‐Xing , Gao Xue‐Wang , Li Jian‐Li , Wu Yue‐Hua , Zhang Tong , Chen Shi‐Lu , Xing Yalan
Published: January 2019

A Copper (II) Acetate Mediated Oxidative Coupling of Styrenes and Ethers Through an Unactivated C(sp3)−H Bond Functionalization

A functionalization of unactivated C(sp3)‐H bond of ethers with styrenes was described. This C−C bond formation has been developed using t‐butyl hydroperoxide (TBHP) as a radical initiator and DBU as an additive agent. Typical ethers underwent a free‐radical addition of styrenes to give direct difunctionalization products with excellent regioselectivity and efficiency. This reaction features good yields and functional group compatibility with simple operation and mild conditions. A plausible reaction mechanism has been proposed. DFT simulation and theory calculation also provided important evidence for the proposed free‐radical mechanism.

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Applications of Thermal Activation, Ball‐milling and Aqueous Medium in Stereoselective Michael Addition of Nitromethane to Enynones Catalyzed by Chiral Squaramides
Authors: Ignatiuk Żaneta A. , Janicki Mikołaj J. , Góra Robert W. , Konieczny Krzysztof , Kowalczyk Rafał
Published: January 2019

Stereoselective addition of nitromethane to conjugated en‐ynones was performed through the application of chiral squaramides. Three non‐classical approaches to promote the addition reaction were tested, including activation of the nucleophile by inorganic base in a biphasic aqueous system, thermal activation, and ball‐milling. Hydrogen‐bonding catalysis was effective in all these methods, providing 1,4‐addition products in high yields and stereoselectivities of up to 98% requiring 1–5 mol% of Cinchona alkaloid squaramide.

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Poly(1,4‐di(2‐thienyl))benzene Facilitating Complete Light‐Driven Water Splitting under Visible Light at High pH
Authors: Oka Kouki , Noguchi Kanako , Suga Takeo , Nishide Hiroyuki , Winther‐Jensen Bjorn
Published: January 2019

The recent discovery that metal‐free polyterthiophene (PTTh) prepared by iodine‐vapor‐assisted polymerization (IVP) can catalyze the hydrogen evolution reaction (HER) when illuminated, and this light‐enhanced electrolysis expresses a non‐Nernstian relation with pH, provides the foundation for further improvement of the photovoltage of the reaction by engineering the band structure of the light‐absorbing polymer. Deviating from an all‐thiophene backbone, using poly(1,4‐di(2‐thienyl))benzene (PDTB) lowers the highest occupied molecular orbital level by ≈0.3 eV compared with polythiophene, and PDTB simultaneously maintains the photoelectrocatalytic properties without an all‐thiophene backbone, resulting in very high conversion rate of 600 mmol(H2) h−1 g−1 at 0 V versus the reversible hydrogen electrode (RHE) at pH 11. PDTB shows the same non‐Nernstian behavior as PTTh with increasing onset potential (versus RHE) at higher pH, and the open circuit potential on PDTB under visible light reaches 1.4 V versus RHE at pH 12. The PDTB photocathode thus produces a photovoltage above the theoretical potential for the complete water‐splitting (1.229 V) and is indeed able to produce hydrogen in a one‐photon‐per‐electron light‐driven water splitting setup with MnOx as the anode at a rate of 6.4 mmol h−1 gPDTB−1.
Synthesis of Crosslinked Chiral Polysiloxanes of Cinchona Alkaloid Derivatives and their Applications in Asymmetric Catalysis
Authors: Kumpuga Bahati Thom , Itsuno Shinichi
Published: January 2019

Crosslinked chiral polysiloxanes containing cinchona alkaloid derivatives were synthesized from poly(methylhydrosiloxane) by hydrosilylation reaction. The C3‐vinyl group of cinchona alkaloid derivatives were easily hydrosilylated with Si−H functional groups of poly(methylhydrosiloxane) by using Pt catalyst. The reaction between cinchona alkaloid dimers and poly(methylhydrosiloxane) and afforded the crosslinked chiral polysiloxanes. Partial hydrolysis of Si−H bonds with Pt catalyst during reaction resulted in a formation of extra crosslinkages of chiral polysiloxanes. Mixed solvent (toluene and DMF) system was employed for a successful immobilization of C6′−OH free cinchona alkaloid derivatives into poly(methylhydrosiloxane). Both cinchona alkaloid C9‐ester and C9‐urethane derivatives were incorporated into poly(methylhydrosiloxane) through Si−C bond. The resulted crosslinked chiral polysiloxanes were insoluble in common organic solvents. Their catalytic performance was evaluated in asymmetric Michael addition reactions. The chiral polysiloxanes of cinchona alkaloid having C6′−OH showed higher enantioselectivities (up to 99% ee) with sufficient catalytic activities in the Michael addition reactions. The chiral polysiloxanes were easily recovered by filtration or centrifugation method and could be reused for several times without losing their catalytic performance.
Hidden Conformations in Aspergillus niger Monoamine Oxidase are Key for Catalytic Efficiency
Authors: Curado‐Carballada Christian , Feixas Ferran , Iglesias‐Fernández Javier , Osuna Sílvia
Published: January 2019

Enzymes exist as an ensemble of conformational states, whose populations can be shifted by substrate binding, allosteric interactions, but also by introducing mutations to their sequence. Tuning the populations of the enzyme conformational states through mutation enables evolution towards novel activity. Herein, Markov state models are used to unveil hidden conformational states of monoamine oxidase from Aspergillus niger (MAO‐N). These hidden conformations, not previously observed by any other technique, play a crucial role in substrate binding and enzyme activity. This reveals how distal mutations regulate MAO‐N activity by stabilizing these hidden, catalytically important conformational states, but also by modulating the communication pathway between both MAO‐N subunits.
A Guiding Principle for Strengthening Crosslinked Polymers: Synthesis and Application of Mobility‐Controlling Rotaxane Crosslinkers
Authors: Sawada Jun , Aoki Daisuke , Otsuka Hideyuki , Takata Toshikazu
Published: January 2019

Three component mobility controlling vinylic rotaxane crosslinkers with two radically polymerizable vinyl groups (RC_Rs) were synthesized to prove that the mobility of the components of the RC_Rs plays a crucial role in determining the properties of rotaxane‐crosslinked polymers (RCPs). RC_Rs (R=H, Me, or Et) were obtained from living ring‐opening polymerization. RCP_Et was prepared using RC_Et, which exhibits the lowest component mobility. The low component mobility is reflected in inferior mechanical strength and stretching ability in tensile stress tests compared to components with good (R=Me) and high (R=H) mobility. However, RCP_Et exhibited significantly higher stress and strain values than the corresponding covalently crosslinked polymers (CCP_Rs). These results indicate that a suitable component mobility substantially enhances the mechanical strength of RCPs. This behavior could serve as a guiding principle for the molecular design of advanced RCs.
Vergleichende Acetonadsorption an Wasser‐ und Eisoberflächen
Authors: Cyran Jenée D. , Backus Ellen H. G. , van Zadel Marc‐Jan , Bonn Mischa
Published: January 2019

Kleine organische Moleküle auf Eis‐ und Wasseroberflächen sind allgegenwärtig in der Natur und beeinflussen diverse Umweltprozesse essentiell. Hier kombinieren wir oberflächenspezifische Summenfrequenzspektroskopie mit einer regelbaren Durchflusszelle um die molekulare Adsorption von Aceton an die Basisfläche von monokristallinem Ih‐Eis mit einer großen Oberfläche zu untersuchen. Durch den direkten Vergleich der Acetonadsorption an der Eis/Luft‐ und Wasser/Luft‐Grenzfläche können wir zwei verschiedene Adsorptionsverhalten identifizieren, die sich durch unterschiedliche Signale der freien OH‐Gruppe und des Wasserstoffbrückennetzwerks für Eis und Wasser zeigen. Die Adsorption an Eis geschieht vorzugsweise durch die Interaktion mit der freien OH‐Gruppe, während die Interaktion von Aceton mit der Oberfläche von Wasser weniger spezifisch erscheint.
Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides
Authors: Amenós Laura , Trulli Laura , Nóvoa Luis , Parra Alejandro , Tortosa Mariola
Published: January 2019

Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched α‐hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively prepared. Functionalization of the carbon–boron bond provides access to different enantiomerically enriched trisubstituted cyclopropanes from a common intermediate.
Extrinsic Heavy Metal Atom Effect on the Solid‐State Room Temperature Phosphorescence of Cyclic Triimidazole
Authors: Cariati Elena , Forni Alessandra , Lucenti Elena , Marinotto Daniele , Previtali Andrea , Righetto Stefania , Botta Chiara , Bold Victor , Kravtsov Victor , Fonari Marina S.
Published: January 2019

Four coordination compounds [Zn3(CH3COO)6(H2O)2](TT)2 [Cd(H2O)6](ClO4)2(TT)2, [Cd(H2O)6](BF4)2(TT)2, [Zn(H2O)6](BF4)2(TT)2 (1–4) accommodating the crystallization induced emissive triimidazo[1,2‐a:1′,2′‐c:1′′,2′′‐e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H‐aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn. In 2 and 3, the heavier Cd atom is responsible for a decrease in the lifetimes of the afterglow emission, despite the presence of tightly overlapped H‐dimers in the crystal structure. Finally, for 4, isostructural with 3, the Zn atom reveals in RTUP lifetime comparable with that of 1.
Controlling the Emergence and Shift Direction of Mechanochromic Luminescence Color of a Pyridine‐Terminated Compound
Authors: Kondo Mizuho , Yamoto Taku , Miura Seiya , Hashimoto Mayuko , Kitamura Chitoshi , Kawatsuki Nobuhiro
Published: January 2019

In this study, mechanochromic luminescence was induced in a complex of mechano‐inactive compounds. Dye/acid complexes containing the same π‐conjugated backbones were prepared. While the luminophore showed blue and red shifts in photoluminescence spectra when combined with different acids by grinding, it exhibited slight mechanoresponsiveness itself. Also, compounds with similar molecular backbones to the dye/acid complex were synthesized to clarify the color change mechanism. The compounds showed both blue and red shifts in photoluminescence and diffuse reflectance spectra upon grinding, indicating that mechanochromic luminescence in the hydrogen‐bonded complex is like its monomeric analogue and that aggregation structure plays an important role in mechanoresponsive behavior rather than the π‐conjugated structure. It was shown that a color change can be mechanically induced by imitating the solid‐state aggregation structure of other mechanoresponsive compounds without synthetic modification.
Design of a Quinoidal Thieno[3,4‐b]thiophene‐Diketopyrrolopyrrole‐Based Small Molecule as n‐Type Semiconductor
Authors: Ren Longbin , Yuan Dafei , Zhu Xiaozhang
Published: January 2019

A quinoidal small‐molecule semiconductor QDPPBTT was synthesized. Organic thin‐film transistor (OTFT) devices based on QDPPBTT showed an electron mobility as high as 0.13 cm2 V−1 s−1 and Ion/Ioff ratio of 106 under ambient conditions. We suggested that 2D extended π‐conjugation and quinoid‐enhancing effect had an important role in electron mobility and stability of n‐type FET devices, which might be a good strategy in designing new material systems.
Nano‐Graphene Oxide Based Multichannel Sensor Arrays towards Sensing of Protein Mixtures
Authors: Behera Pradipta , De Mrinmoy
Published: January 2019

Optical array‐based sensors are attractive candidates for the detection of various bio‐analytes due to their convenient fabrication and measurements. For array‐based sensors, multichannel arrays are more advantageous and used frequently in many electronic sensors. But most reported optically array based sensors are constructed on a single channel array. This difficulty is mainly instigated from the overlap in optical responses. In this report we have used nano‐graphene oxide (nGO) and suitable fluorophores as sensor elements to construct a multichannel sensor array for the detection of protein analytes. By using the optimized multichannel array we are able to detect different proteins and mixtures of proteins with 100 % classification accuracy at sub‐nanomolar concentration. This modified method expedites the sensing analysis as well as minimizes the use of both analyte and sensor elements in array‐based protein sensing. We have also used this system for the single channel array‐based sensing to compare the sensitivity and the efficacy of these two systems for other applications. This work demonstrated an intrinsic trade‐off associated with these two methods which may be necessary to balance for array‐based analyte detections.
The hierarchical metaregression approach and learning from clinical evidence
Authors: Verde Pablo Emilio
Published: January 2019

The hierarchical metaregression (HMR) approach is a multiparameter Bayesian approach for meta‐analysis, which generalizes the standard mixed effects models by explicitly modeling the data collection process in the meta‐analysis. The HMR allows to investigate the potential external validity of experimental results as well as to assess the internal validity of the studies included in a systematic review. The HMR automatically identifies studies presenting conflicting evidence and it downweights their influence in the meta‐analysis. In addition, the HMR allows to perform cross‐evidence synthesis, which combines aggregated results from randomized controlled trials to predict effectiveness in a single‐arm observational study with individual participant data (IPD). In this paper, we evaluate the HMR approach using simulated data examples. We present a new real case study in diabetes research, along with a new R package called jarbes (just a rather Bayesian evidence synthesis), which automatizes the complex computations involved in the HMR.
Essential Oil Composition of Different Plant Parts from CroatianPetasites albus(L.) Gaertn.andPetasites hybridus(L.) G.Gaertn., B.Mey. & Scherb.(Asteraceae)
Authors: Friščić Maja , Jerković Igor , Marijanović Zvonimir , Dragović Sanja , Hazler Pilepić Kroata , Maleš Željan
Published: January 2019

Essential oil compositions of fresh leaves, flower stems and rhizomes obtained by hydrodistillation from different Croatian populations ofPetasites albus(L.) Gaertn.andPetasites hybridus(L.) G.Gaertn., B.Mey. & Scherb.(four of each species) were investigated using gas chromatography‐flame ionization detection and gas chromatography‐mass spectrometry. Altogether, 118 constituents were identified, accounting for 81.19–96.81 % of total oil composition. All essential oils were characterized by oxygenated sesquiterpenes, with distinct compounds recorded for both investigated species. Clear separation between the two species was confirmed by principal component analysis and hierarchical cluster analysis. This is the first study that recorded intraspecific variations of essential oil constituents fromP. albusandP. hybridus. Obtained results could contribute to the understanding of their medicinal and nutritional value.
Differently Tagged Probes for Protein Profiling of Mitochondria
Authors: Dong Jia , Hong Danqi , Lang Wenjie , Huang Jintao , Qian Linghui , Zhu Qing , Li Lin , Ge Jingyan
Published: January 2019

The mitochondrion is one of the most important organelles in the eukaryotic cell. Characterization of the mitochondrial proteome is a prerequisite for understanding its cellular functions at the molecular level. Here we report a proteomics method based on mitochondrion‐targeting groups and click chemistry. In our strategy, three different mitochondrion‐targeting moieties were each augmented with a clickable handle and a cysteine‐reactive group. Fluorescence‐based bioimaging and fractionation experiments clearly showed that most signals arising from the labels were localized in the mitochondria of cells, as a result of covalent attachment between probe and target proteins. The three probes had distinct profiling characteristics. Furthermore, we successfully identified more than two hundred mitochondrial proteins. The results showed that different mitochondrion‐targeting groups targeted distinct proteins with partial overlap. Most of the labeled proteins were localized in the mitochondrial matrix and inner mitochondrial membrane. Our results provide a tool for chemoproteomic analysis of mitochondrion‐related proteins.
Charge Transfer Reactions in CO2 Electroreduction on Manganese Doped Ceria
Authors: Huang Zhidong , Shang Lei , Qi Huiying , Zhao Zhe , Tu Baofeng , Yang Weishen , Cheng Mojie
Published: January 2019

The key to electrochemical conversion of carbon dioxide (CO2) into fuels lies in effient charge transfer reactions. Here, we depict from the polarzation resistance analysis that the electroreduction of CO2 to CO on manganese doped ceria (CMO) passes through two elementary charge transfer reactions. One reaction is asscociated with
to
and another associated with
to CO. As the rate determing step, the first one has an apparenent acitvation energy of 178.7 kJ mol−1 and a pressure dependence of
. The second one has an apparent acitvation energy of 100.6 kJ mol−1 and a pressure dependence of
. Based on the experimental results, we give the kenetic expression for the CO2 electroreduction rate on CMO.
Electromigration in Lithium Whisker Formation Plays Insignificant Role during Electroplating
Authors: Rulev Alexey A. , Sergeev Artem V. , Yashina Lada V. , Jacob Timo , Itkis Daniil M.
Published: January 2019

Plating of metallic Li results in deposition of needle‐like structures, whose prevention is a fundamental challenge that currently restricts the development and application of high energy Li‐metal rechargeable batteries. Over the last decades, a number of mechanisms were proposed to explain morphological instabilities of planar crystallization fronts. The suggested reasons for non‐uniform deposition include Li+ concentration gradients in the nutrient phase, accelerated electromigration to the tip of the growing needle, specific nucleation behavior, mechanical properties of the solid‐electrolyte interphase, and many more. Here, we unravel the role of electromigration currents by adding indifferent cations (TBA+, TEA+) to screen for non‐uniform electric fields, thus, suppressing migration‐driven mass‐transfer. Nearly full exclusion of electromigration currents showed no impact on the morphology of electrodeposited lithium. Therefore, the role of electromigration seems negligible, and electric field edge effects are undoubtedly not the main driving force for filament growth during Li plating.
Diketopyrrolopyrrole Bis‐Phosphonate Conjugate: A New Fluorescent Probe for In Vitro Bone Imaging
Authors: Chiminazzo Andrea , Borsato Giuseppe , Favero Alessia , Fabbro Chiara , McKenna Charles E. , Dalle Carbonare Luca Giuseppe , Valenti Maria Teresa , Fabris Fabrizio , Scarso Alessandro
Published: January 2019

The synthesis of a conjugate molecule between an unusual red‐fluorescent diketopyrrolopyrrole (DPP) unit and a bis‐phosphonate (BP) precursor by a click‐chemistry strategy to target bone tissue and monitor the interaction is reported. After thorough investigation, conjugation through a triazole unit between a γ‐azido rather than a β‐azido BP and an alkyne‐functionalized DPP fluorophore group turned out to be the winning strategy. Visualization of the DPP‐BP conjugate on osteoclasts and specific antiresorption activity were successfully demonstrated.
Carboranyl Analogues of Celecoxib with Potent Cytostatic Activity against Human Melanoma and Colon Cancer Cell Lines
Authors: Buzharevski Antonio , Paskas Svetlana , Sárosi Menyhárt‐Botond , Laube Markus , Lönnecke Peter , Neumann Wilma , Mijatovic Sanja , Maksimovic‐Ivanic Danijela , Pietzsch Jens , Hey‐Hawkins Evamarie
Published: January 2019

Nonsteroidal anti‐inflammatory drugs (NSAIDs) are the most common way of treating inflammatory disorders. Their widespread use helped reveal their other modes of action as pharmaceuticals, such as a profound effect on various cancers. Celecoxib has proven to be a very prominent member of this group with cytostatic activities. On the other hand, the highly dynamic field of drug design is constantly searching for new ways of modifying known structures to obtain more powerful and less harmful drugs. A very interesting development is the implementation of carboranes in pharmacologically active structures, mostly as phenyl mimetics. Herein we report the synthesis of three carborane‐containing derivatives of the COX‐2‐selective NSAID celecoxib. The new compounds proved to have promising cytostatic potential against various melanoma and colorectal adenocarcinoma cell lines. Inhibited proliferation accompanied by caspase‐independent apoptotic cell death was found to be the main cause of decreased cell viability upon treatment with the most efficient celecoxib analogue, 3 b (4‐[5‐(1,7‐dicarba‐closo‐dodecaboranyl)‐3‐trifluoromethyl‐1H‐pyrazol‐1‐yl]‐1‐methylsulfonylbenzene).
Synthesis and Anticancer Evaluation of 1,4‐Naphthoquinone Derivatives Containing a Phenylaminosulfanyl Moiety
Authors: Ravichandiran Palanisamy , Subramaniyan Sivakumar Allur , Kim Seon‐Young , Kim Jong‐Soo , Park Byung‐Hyun , Shim Kwan Seob , Yoo Dong Jin
Published: January 2019

1,4‐Naphthoquinones are exceptional building blocks in organic synthesis and have been used to synthesize several well‐known pharmaceutically active agents. Herein we report the synthesis, structural characterization, and biological evaluation of new phenylaminosulfanyl‐1,4‐naphthoquinone derivatives. We evaluated the cytotoxic activity of the synthesized compounds against three human cancer cell lines: A549, HeLa, and MCF‐7. Most of the synthesized compounds displayed potent cytotoxic activity. Specifically, compounds 5 e [3,5‐dichloro‐N‐(4‐((4‐((1,4‐dioxo‐3‐(phenylthio)‐1,4‐dihydronaphthalen‐2‐yl)amino)phenyl)sulfonyl)phenyl)benzamide], 5 f [N‐(4‐((4‐((1,4‐dioxo‐3‐(phenylthio)‐1,4‐dihydronaphthalen‐2‐yl)amino)phenyl)sulfonyl)phenyl)‐3,5‐dinitrobenzamide], and 5 p [N‐(4‐((4‐((1,4‐dioxo‐3‐(phenylthio)‐1,4‐dihydronaphthalen‐2‐yl)amino)phenyl)sulfonyl)phenyl)thiophene‐2‐carboxamide] showed remarkable cytotoxic activity. The synthesized compounds showed low toxicity in normal human kidney HEK293 cells. The cytotoxic mechanism of compounds 5 e, 5 f, and 5 p was explored in MCF‐7 cells. The results confirmed that these three compounds induce apoptosis and arrest the cell cycle at the G1 phase. In addition, compounds 5 e, 5 f, and 5 p were found to induce apoptosis via upregulation of caspase‐3 and caspase‐7 proteins as well as by upregulation of the gene expression levels of caspases‐3 and ‐7. Our findings demonstrate that compounds 5 e, 5 f, and 5 p could be potent agents against a number of cancer types.
Magnetic Traits in CoO‐Core@CoFe2O4‐shell Like Nanoparticles
Authors: Flores‐Martinez Nancy , Roemer Margot , Gam‐Derouich Sarra , Beaunier Patricia , Habrovsky David , Ammar Souad
Published: January 2019

Antiferromagnetic (AF) CoO pseudo‐single crystals 125±20 nm in diameter were prepared by forced hydrolysis in polyol and used as seeds to grow a poly‐ and nano‐crystalline (5 nm in diameter) ferrimagnetic (F) CoFe2O4 shell. Transmission electron microscopy (TEM) showed a certain epitaxy between the face‐centered cubic lattices of the AF rock‐salt core and the F spinel shell. Magnetometry measurements do not evidence any exchange bias feature between the two phases in direct contact. The hysteresis loops recorded between 7 and −7 T after cooling the composite particles from 400 K (between the Néel and the Curie temperatures of the AF and F phases, respectively) to 5 K, with and without a cooling magnetic field (μ0HFC=+7 T), are the same, meaning that the AF core does not allow any spin pinning on the CoFe2O4 nanocrystals. Nevertheless, differences exist between these magnetic data and those collected on two CoFe2O4 reference particles: the low temperature coercive field of the composite is between those of 5 nm sized single‐crystals and their assembly as submicrometer polycrystals. This order was also observed for the blocking temperature, although the constituting CoFe2O4 nanocrystals of all these particles, the composite and the two references, were the same. Advanced analysis by X‐ray diffraction and TEM established that the coherent crystallographic domain length of the ferrite phase and the magnetic behavior of the three systems are interdependent. Depending on the growth conditions of the CoFe2O4 phase, a relative epitaxy between the nanocrystals may exist. It is much greater in the polycrystalline CoFe2O4 particles than in their CoO−CoFe2O4 core‐shell counterparts, and does not occur in free single crystal CoFe2O4 particles.
Electrochemical Characterization of Graphene Microelectrodes for Biological Applications
Authors: Körbitzer Berit , Krauß Peter , Belle Stefan , Schneider Jörg J. , Thielemann Christiane
Published: January 2019

Graphene is a promising material both as a coating for existing neural electrodes as well as for transparent electrodes made exclusively from graphene. We studied graphene‐based microelectrodes by investigating their recording and stimulation properties in order to evaluate their suitability for neuronal implants. In this work, we compare three different electrode material compositions. Microelectrode arrays (MEA) with an electrode size of about 700 μm2 were prepared of gold, graphene on gold, and plain graphene on glass substrate. In order to reduce polymer contamination during graphene transfer, we employed a polymer‐free transfer and lift‐off process. Impedance studies revealed a value of 2.3 MΩ at 1 kHz for plain, and 0.88 MΩ for graphene on gold. Neuronal recording experiments showed a sufficient SNR for both graphene‐based materials and a stable impedance, unaffected by surface degradation metal electrodes are known for. Stimulation measurements yielded a charge injection capacity of 0.15 mC/cm2 using biphasic pulses of 1 ms and 1 μA transparent graphene electrodes. Cyclic voltammetry revealed a large voltage range of −1.4 V to +1.6 V before water electrolysis occurs. Graphene‐coated gold microelectrodes show enhanced recording properties, whereas plain graphene electrodes might be better suited for stimulation applications.
Selectivity in Photodynamic Action: Higher Activity of Mitochondria Targeting Photosensitizers in Cancer Cells
Authors: Ucar Esma , Seven Ozlem , Lee Dayoung , Kim Gyoungmi , Yoon Juyoung , Akkaya Engin U.
Published: January 2019

Among the pathways for improving the practice of photodynamic therapy of cancer, increasing the selectivity of photodynamic action is an obvious choice. Considering the different characteristics of mitochondria in normal cells and cancer cells, we designed mitochondria‐targeting photosensitizers. We now demonstrate for the first time that mitochondria‐targeted photosensitizers by triphenylphosphonium (TPP) derivatization are more selective for cancer cells compared to normal cells, presumably due to the larger membrane potential of cancer‐cell mitochondria allowing more efficient accumulation of the photosensitizer.