bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inverse Opal Scaffolds with Gradations in Mineral Content for Spatial Control of Osteogenesis
Authors: Zhu Chunlei , Qiu Jichuan , Pongkitwitoon Suphannee , Thomopoulos Stavros , Xia Younan 
Published: May 2018

AbstractThe design and fabrication of inverse opal scaffolds with gradations in mineral content to achieve spatial control of osteogenesis are described. The gradient in mineral content is established via the diffusion‐limited transport of hydroxyapatite nanoparticles in a closely packed lattice of gelatin microbeads. The mineral‐graded scaffold has an array of uniform pores and interconnected windows to facilitate efficient transport of nutrients and metabolic wastes, ensuring high cell viability. The graded distribution of mineral content can provide biochemical and mechanical cues for spatially regulating the osteogenic differentiation of adipose‐derived stromal cells. This new class of scaffolds holds promise for engineering the interfaces between mineralized and unmineralized tissues.
Tissue Mimicry in Morphology and Composition Promotes Hierarchical Matrix Remodeling of Invading Stem Cells in Osteochondral and Meniscus Scaffolds
Authors: Stuckensen Kai , Schwab Andrea , Knauer Markus , Muiños‐López Emma , Ehlicke Franziska , Reboredo Jenny , Granero‐Moltó Froilán , Gbureck Uwe , Prósper Felipe , Walles Heike , Groll Jürgen 
Published: May 2018

AbstractAn integral approach toward in situ tissue engineering through scaffolds that mimic tissue with regard to both tissue architecture and biochemical composition is presented. Monolithic osteochondral and meniscus scaffolds are prepared with tissue analog layered biochemical composition and perpendicularly oriented continuous micropores by a newly developed cryostructuring technology. These scaffolds enable rapid cell ingrowth and induce zonal‐specific matrix synthesis of human multipotent mesenchymal stromal cells solely through their design without the need for supplementation of soluble factors such as growth factors.
Quantifying Polaron Formation and Charge Carrier Cooling in Lead‐Iodide Perovskites
Authors: Bretschneider Simon A. , Ivanov Ivan , Wang Hai I. , Miyata Kiyoshi , Zhu Xiaoyang , Bonn Mischa 
Published: May 2018

AbstractNotwithstanding the success of lead‐halide perovskites in emerging solar energy conversion technologies, many of the fundamental photophysical phenomena in this material remain debated. Here, the initial steps following photogeneration of free charge carriers in lead‐iodide perovskites are studied, and timescales of charge carrier cooling and polaron formation, as a function of temperature and charge carrier excess energy, are quantified. It is found, using terahertz time‐domain spectroscopy (THz‐TDS), that the observed femtosecond rise in the photoconductivity can be described very well using a simple model of sequential charge carrier cooling and polaron formation. For excitation above the bandgap, the carrier cooling time depends on the charge carrier excess energy and lattice temperature, with cooling rates varying between 1 and 6 meV fs−1, depending on the cation. While carrier cooling depends on the cation, polaron formation occurs within ≈400 fs in CH3NH3PbI3(MAPbI3), CH(NH2)2PbI3(FAPbI3), and CsPbI3. Its formation time is independent of temperature between 160 and 295 K. The very similar polaron formation dynamics observed for the three perovskites points to the critical role of the inorganic lattice, rather than the cations, for polaron formation.
A 1300 mm2 Ultrahigh‐Performance Digital Imaging Assembly using High‐Quality Perovskite Single Crystals
Authors: Liu Yucheng , Zhang Yunxia , Zhao Kui , Yang Zhou , Feng Jiangshan , Zhang Xu , Wang Kang , Meng Lina , Ye Haochen , Liu Ming , Liu Shengzhong (Frank) 
Published: May 2018

AbstractBy fine‐tuning the crystal nucleation and growth process, a low‐temperature‐gradient crystallization method is developed to fabricate high‐quality perovskite CH3NH3PbBr3 single crystals with high carrier mobility of 81 ± 5 cm2 V−1 s−1 (>3 times larger than their thin film counterpart), long carrier lifetime of 899 ± 127 ns (>5 times larger than their thin film counterpart), and ultralow trap state density of 6.2 ± 2.7 × 109 cm−3 (even four orders of magnitude lower than that of single‐crystalline silicon wafers). In fact, they are better than perovskite single crystals reported in prior work: their application in photosensors gives superior detectivity as high as 6 × 1013 Jones, ≈10–100 times better than commercial sensors made of silicon and InGaAs. Meanwhile, the response speed is as fast as 40 µs, ≈3 orders of magnitude faster than their thin film devices. A large‐area (≈1300 mm2) imaging assembly composed of a 729‐pixel sensor array is further designed and constructed, showing excellent imaging capability thanks to its superior quality and uniformity. This opens a new possibility to use the high‐quality perovskite single‐crystal‐based devices for more advanced imaging sensors.
Laminated Object Manufacturing of 3D‐Printed Laser‐Induced Graphene Foams
Authors: Luong Duy Xuan , Subramanian Ajay K. , Silva Gladys A. Lopez , Yoon Jongwon , Cofer Savannah , Yang Kaichun , Owuor Peter Samora , Wang Tuo , Wang Zhe , Lou Jun , Ajayan Pulickel M. , Tour James M. 
Published: May 2018

AbstractLaser‐induced graphene (LIG), a graphene structure synthesized by a one‐step process through laser treatment of commercial polyimide (PI) film in an ambient atmosphere, has been shown to be a versatile material in applications ranging from energy storage to water treatment. However, the process as developed produces only a 2D product on the PI substrate. Here, a 3D LIG foam printing process is developed on the basis of laminated object manufacturing, a widely used additive‐manufacturing technique. A subtractive laser‐milling process to yield further refinements to the 3D structures is also developed and shown here. By combining both techniques, various 3D graphene objects are printed. The LIG foams show good electrical conductivity and mechanical strength, as well as viability in various energy storage and flexible electronic sensor applications.
A Living‐Dead Magnetic Layer at the Surface of Ferrimagnetic DyTiO3 Thin Films
Authors: Aeschlimann Raphaël , Preziosi Daniele , Scheiderer Philipp , Sing Michael , Valencia Sergio , Santamaria Jacobo , Luo Chen , Ryll Hanjo , Radu Florin , Claessen Ralph , Piamonteze Cinthia , Bibes Manuel 
Published: May 2018

AbstractWhen ferromagnetic films become ultrathin, key properties such as the Curie temperature and the saturation magnetization are usually depressed. This effect is thoroughly investigated in magnetic oxides such as half‐metallic manganites, but much less in ferrimagnetic insulating perovskites such as rare‐earth titanates RTiO3, despite their appeal to design correlated 2D electron gases. Here, the magnetic properties of epitaxial DyTiO3 thin films are reported. While films thicker than about 50 nm show a bulk‐like response, at low thickness a surprising increase of the saturation magnetization is observed. This behavior is described using a classical model of a “dead layer” but assuming that this layer is actually “living,” that is, it responds to the magnetic field with a strong paramagnetic susceptibility. Through depth‐dependent X‐ray absorption and photoemission spectroscopy, it is shown that the “living‐dead layer” corresponds to surface regions where magnetic (S = 1/2) Ti3+ ions are replaced by nonmagnetic Ti4+ ions. Hysteresis cycles at the Dy M5 and Ti L3 edges indicate that the surface Ti4+ ions decouple the Dy3+ ions, thus unleashing their strong paramagnetic response. Finally, it is shown how capping the DyTiO3 film can help increase the Ti3+ content near the surface and thus recover a better ferrimagnetic behavior.
An Unprecedented Stimuli‐Controlled Single‐Crystal Reversible Phase Transition of a Metal–Organic Framework and Its Application to a Novel Method of Guest Encapsulation
Authors: Tan Fangchang , López‐Periago Ana , Light Mark E. , Cirera Jordi , Ruiz Eliseo , Borrás Alejandro , Teixidor Francesc , Viñas Clara , Domingo Concepción , Planas José Giner 
Published: May 2018

AbstractThe flexibility and unexpected dynamic behavior of a third‐generation metal–organic framework are described for the first time. The synthetic strategy is based on the flexibility and spherical shape of dipyridyl‐based carborane linkers that act as pillars between rigid Co/BTB (BTB: 1,3,5‐benzenetricarboxylate) layers, providing a 3D porous structure (1). A phase transition of the solid can be induced to generate a new, nonporous 2D structure (2) without any loss of the carborane linkers. The structural transformation is visualized by snapshots of the multistep single‐crystal‐to‐single‐crystal transformation by single‐crystal and powder X‐ray diffraction. Poor hydrogen bond acceptors such as MeOH, CHCl3 or supercritical CO2 induce such a 3D to 2D transformation. Remarkably, the transformation is reversible and the 2D phase 2 is further converted back into 1 by heating in dimethylformamide. The energy requirements involved in such processes are investigated using periodic density functional theory calculations. As a proof of concept for potential applications, encapsulation of C60 is achieved by trapping this molecule during the reversible 2D to 3D phase transition, whereas no adsorption is observed by straight solvent diffusion into the pores of the 3D phase.
Green Fabrication of Amphiphilic Quaternized β‐Chitin Derivatives with Excellent Biocompatibility and Antibacterial Activities for Wound Healing
Authors: Xu Huan , Fang Zehong , Tian Weiqun , Wang Yanfeng , Ye Qifa , Zhang Lina , Cai Jie 
Published: May 2018

AbstractBacterial infection has always been a great threat to public health, and new antimicrobials to combat it are urgently needed. Here, a series of quaternized β‐chitin derivatives is prepared simply and homogeneously in an aqueous KOH/urea solution, which is a high‐efficiency, energy‐saving, and “green” route for the modification of chitin. The mild reaction conditions keep the acetamido groups of β‐chitin intact and introduce quaternary ammonium groups on the primary hydroxyl at the C‐6 position of the chitin backbone, allowing the quaternized β‐chitin derivatives (QCs) to easily form micelles. These QCs are found to exhibit excellent antimicrobial activities against Escherichia coli, Staphylococcus aureus, Candida albicans, and Rhizopus oryzae with minimum inhibitory concentrations (MICs) of 8, 12, 60, and 40 µg mL−1, respectively. As a specific highlight, their inherent outstanding biocompatibility and significant accelerating effects on the healing of uninfected, E. coli‐infected, and S. aureus‐infected wounds imply that these novel polysaccharide‐based materials can be used as dressings for clinical skin regeneration, particularly for infected wounds.
Diamond‐Based All‐Carbon Photodetectors for Solar‐Blind Imaging
Authors: Lin Chao‐Nan , Lu Ying‐Jie , Yang Xun , Tian Yong‐Zhi , Gao Chao‐Jun , Sun Jun‐Lu , Dong Lin , Zhong Fang , Hu Wei‐Da , Shan Chong‐Xin 
Published: May 2018

AbstractSingle‐crystalline diamond wafers are synthesized, and all‐carbon solar‐blind photodetectors are constructed based on the diamond with interdigitated graphite as electrodes. The graphite electrodes are made by laser‐induced graphitization of the diamond. The peak responsivity of the photodetector is 21.8 A W−1, and detectivity is 1.39 × 1012 cm Hz1/2 W−1 when the bias voltage is 50 V, it is noted that both of these are among the best values ever reported for diamond‐based photodetectors. The photodetectors are employed as the sensing pixels in an imaging system, and a clear image is obtained, which is the first report on solar‐blind imaging of diamond photodetectors. The results reported in this paper provide a facile approach to high‐performance diamond solar‐blind photodetectors and their applications in solar‐blind imaging, thus may address a significant step toward the preparation and application of diamond photodetectors.
Organic Solvent and Surfactant Free Fluorescent Organic Nanoparticles by Laser Ablation of Aggregation‐Induced Enhanced Emission Dyes
Authors: Lim Chang‐Keun , Popov Anton A. , Tselikov Gleb , Heo Jeongyun , Pliss Artem , Kim Sehoon , Kabashin Andrei V. , Prasad Paras N. 
Published: May 2018

AbstractLess toxic and highly fluorescent nanoparticles are in high demand to image biological events and early‐stage disease. A strategy to fabricate highly fluorescent organic nanoparticles by laser ablation of aggregation‐induced enhanced emission (AIE) luminophores, which are free of any organic solvent and surfactant, is presented. As these dyes provide no concentration quenching, the increased number of photoluminescent molecules in a nanoparticle produces bright fluorescence even with their small size (<2 nm), making them highly suitable for intracellular uptake and imaging for a variety of biomedical applications. The design and synthesis of a new AIE luminophore, DCEtDCS, are reported and its photoluminescent quantum yield enhancement up to 58% in the aggregated state is demonstrated. Extremely stable nanoparticles of this luminophore with a narrow size distribution, by laser ablation in water are reported and its superior optical properties that are comparable to quantum dots are verified. The highly negative surface charge of these nanoparticles impedes cellular uptake, but when the surface is coated with chitosan, a cationic polymer, intracellular uptake in microglia is achieved. The strategy provides a novel tool to produce in water, ultrasmall and surfactant‐free highly fluorescent organic nanoparticles suitable for biomedical applications.
Large‐Area Lasing and Multicolor Perovskite Quantum Dot Patterns
Authors: Lin Chun Hao , Zeng Qingji , Lafalce Evan , Yu Shengtao , Smith Marcus J. , Yoon Young Jun , Chang Yajing , Jiang Yang , Lin Zhiqun , Vardeny Zeev Valy , Tsukruk Vladimir V. 
Published: May 2018

AbstractHerein, a novel orthogonal lithography process is reported to pattern all‐inorganic perovskite CsPbX3 (X = Cl, Br, I) quantum dot (QD) arrays which cannot be patterned with traditional approaches. This approach involves a combination of fluorinated polymer and solvent to resolve issues of polar–nonpolar solvent constraints thus enabling the fabrication of complex patterns with high optical gain and multicolor emission. This approach is utilized to fabricate high‐resolution large‐area arrays of microdisk lasers and multicolor (binary and ternary emission) pixels. The optical cavity modes of CsPbBr3 QD microdisk lasers are readily controlled by tuning the disk size, where the mode spacing decreases while the number of modes increases with increasing disk diameter. Finally, the versatility of this approach for the integration of environmentally sensitive QDs with different emission signatures and composition on the same chip, while achieving high‐density, high‐resolution large‐area QD arrays with multicolor pixels, is demonstrated.
Visible‐Light‐Mediated Dearomatization/Cyanation Cascade Reaction of Indoles: Access to Highly Functionalized Spiro‐γ‐lactam Indolines with Two Contiguous Sterically Congested Quaternary Carbon Stereocenters
Authors: Wang Qiang , Qu Yi , Xia Qing , Song Hongjian , Song Haibin , Liu Yuxiu , Wang Qingmin 
Published: May 2018

AbstractA protocol for visible‐light‐induced radical dearomatization/cyanation cascade reaction of indole derivatives is reported. This protocol provides straightforward access to gem‐difluorinated and cyanated 3,3’‐spirocyclic indolines with moderate to excellent diastereoselectivity and permits the construction of two contiguous sterically congested quaternary carbon stereocenters.magnified image
Asymmetric Synthesis of Fused Bicyclic N,O‐ and O,O‐Acetals via Cascade Reaction by Gold(I)/N,N′‐Dioxide‐Nickel(II) Bimetallic Relay Catalysis
Authors: Hu Bowen , Li Jun , Cao Weidi , Lin Qianchi , Yang Jian , Lin Lili , Liu Xiaohua , Feng Xiaoming 
Published: May 2018

AbstractAn efficient catalytic asymmetric cyclization/inverse‐electron‐demand hetero‐Diels‐Alder cascade reaction of β,γ‐unsaturated α‐ketoesters with alkyl amides or alcohols were accomplished. The process was based on the utilization bimetallic catalyst system with achiral gold(I) catalyst and chiral N,N′‐dioxide/Ni(II) catalyst, delivering a variety of fused bicyclic N,O‐acetals or O,O‐acetals in up to 99% yield and 99% ee with >19:1 dr under mild reaction conditions. Based on the control experiments and previous studies, a possible reaction pathway of bimetallic relay catalysis cascade reactions was presented.magnified image
The relationship between organizational policies and practices and work limitations among hospital patient care workers
Authors: Sparer Emily H. , Boden Leslie I. , Sorensen Glorian , Dennerlein Jack T. , Stoddard Anne , Wagner Gregory R. , Nagler Eve M. , Hashimoto Dean M. , Hopcia Karen , Sabbath Erika L. 
Published: May 2018

ObjectiveWe examined relationships between organizational policies and practices (OPPs) (safety practices, ergonomic practices, and people‐oriented culture) and work limitations in a sample of hospital workers.MethodsWe used the 6‐item Work Limitations Questionnaire (WLQ) to assess workers’ perceptions of health‐related work limitations. Self‐reported OPPs and the WLQ were collected from workers in Boston, Massachusetts (n = 1277). We conducted random‐intercept multi‐level logistic regression models for each OPP using stepwise selection of covariates.ResultsAs the unit‐average ergonomic practice score increased by one, the odds of a worker reporting work limitations decreased by approximately 39% (P‐value = 0.018), adjusted for job title, age, and body mass index. A similar relationship existed for people‐oriented culture (P‐value = 0.038). The association between safety practices and work limitations was similar, but not statistically significant.ConclusionsThis study demonstrated the importance of workplace OPPs. OPPs that promote positive and supportive environments and that foster improvements in ergonomics may help reduce work limitations.
Solvent Effects on the Actinic Step of Donor–Acceptor Stenhouse Adduct Photoswitching
Authors: Lerch Michael M. , Di Donato Mariangela , Laurent Adèle D. , Medved' Miroslav , Iagatti Alessandro , Bussotti Laura , Lapini Andrea , Buma Wybren Jan , Foggi Paolo , Szymański Wiktor , Feringa Ben L. 
Published: May 2018

AbstractDonor–acceptor Stenhouse adducts (DASAs) are negative photochromes that switch with visible light and are highly promising for applications ranging from smart materials to biological systems. However, the strong solvent dependence of the photoswitching kinetics limits their application. The nature of the photoswitching mechanism in different solvents is key for addressing the solvatochromism of DASAs, but as yet has remained elusive. Here, we employ spectroscopic analyses and TD‐DFT calculations to reveal changing solvatochromic shifts and energies of the species involved in DASA photoswitching. Time‐resolved visible pump‐probe spectroscopy suggests that the primary photochemical step remains the same, irrespective of the polarity and protic nature of the solvent. Disentangling the different factors determining the solvent‐dependence of DASA photoswitching, presented here, is crucial for the rational development of applications in a wide range of different media.
Access to the Bis‐benzene Cobalt(I) Sandwich Cation and its Derivatives: Synthons for a “Naked” Cobalt(I) Source?
Authors: Meier Stefan C. , Holz Albina , Kulenkampff Jan , Schmidt Alexei , Kratzert Daniel , Himmel Daniel , Schmitz Dominik , Scheidt Ernst‐Wilhelm , Scherer Wolfgang , Bülow Christine , Timm Martin , Lindblad Rebecka , Akin Scott T. , Zamudio‐Bayer Vicente , von Issendorff Bernd , Duncan Michael A. , Lau J. Tobias , Krossing Ingo 
Published: May 2018

AbstractThe synthesis and structural characterization of the hitherto unknown parent Co(bz)2+ (bz=benzene) complex and several of its derivatives are described. Their synthesis starts either from a CoCO5+ salt, or directly from Co2(CO)8 and a Ag+ salt. Stability and solubility of these complexes was achieved by using the weakly coordinating anions (WCAs) [Al(ORF)4]− and [F{Al(ORF)3}2]− {RF=C(CF3)3} and the solvent ortho‐difluorobenzene (o‐DFB). The magnetic properties of Co(bz)2+ were measured and compared in the condensed and gas phases. The weakly bound Co(o‐dfb)2+ salts are of particular interest for the preparation of further CoI salts, for example, the structurally characterized low‐coordinate 12 valence electron Co(PtBu3)2+ and Co(NHC)2+ salts.
Olefin Cyclopropanation by Radical Carbene Transfer Reactions Promoted by Cobalt(II)/Porphyrinates: Active‐Metal‐Template Synthesis of [2]Rotaxanes
Authors: Alcântara Arthur F. P. , Fontana Liniquer A. , Rigolin Vitor H. , Andrade Yuri F. S. , Ribeiro Marcos A. , Barros Wdeson P. , Ornelas Catia , Megiatto Jackson D. 
Published: May 2018

AbstractA CoII/porphyrinate‐based macrocycle in the presence of a 3,5‐diphenylpyridine axial ligand functions as an endotopic ligand to direct the assembly of [2]rotaxanes from diazo and styrene half‐threads, by radical‐carbene‐transfer reactions, in excellent 95 % yield. The method reported herein applies the active‐metal‐template strategy to include radical‐type activation of ligands by the metal‐template ion during the organometallic process which ultimately yields the mechanical bond. A careful quantitative analysis of the product distribution afforded from the rotaxane self‐assembly reaction shows that the CoII/porphyrinate subunit is still active after formation of the mechanical bond and, upon coordination of an additional diazo half‐thread derivative, promotes a novel intercomponent C−H insertion reaction to yield a new rotaxane‐like species. This unexpected intercomponent C−H insertion illustrates the distinct reactivity brought to the CoII/porphyrinate catalyst by the mechanical bond.
Stabilising Peptoid Helices Using Non‐Chiral Fluoroalkyl Monomers
Authors: Gimenez Diana , Aguilar Juan A. , Bromley Elizabeth H. C. , Cobb Steven L. 
Published: May 2018

AbstractStability towards protease degradation combined with modular synthesis has made peptoids of considerable interest in the fields of chemical biology, medicine, and biomaterials. Given their tertiary amide backbone, peptoids lack the capacity to hydrogen‐bond, and as such, controlling secondary structure can be challenging. The incorporation of bulky, charged, or chiral aromatic monomers can be used to control conformation but such building blocks limit applications in many areas. Through NMR and X‐ray analysis we demonstrate that non‐chiral neutral fluoroalkyl monomers can be used to influence the Kcis/trans equilibria of peptoid amide bonds in model systems. The cis‐isomer preference displayed is highly unprecedented given that neither chirality nor charge is used to control the peptoid amide conformation. The application of our fluoroalkyl monomers in the design of a series of linear peptoid oligomers that exhibit stable helical structures is also reported.
Radical trans‐Hydroboration of Alkynes with N‐Heterocyclic Carbene Boranes
Authors: Shimoi Masaki , Watanabe Takashi , Maeda Katsuhiro , Curran Dennis P. , Taniguchi Tsuyoshi 
Published: May 2018

AbstractHydroboration of internal alkynes with N‐heterocyclic carbene boranes (NHC‐boranes) occurs to provide stable NHC (E)‐alkenylboranes upon thermolysis in the presence of di‐tert‐butyl peroxide. The E isomer results from an unusual trans‐hydroboration, and the E/Z selectivity is typically high (90:10 or greater). Evidence suggests that this hydroboration occurs by a radical‐chain reaction involving addition of an NHC‐boryl radical to an alkyne to give a β‐NHC‐borylalkenyl radical. Ensuing hydrogen abstraction from the starting NHC‐borane provides the product and returns the starting NHC‐boryl radical. Experiments suggest that the observed trans‐selectivity results from kinetic control in the hydrogen‐transfer reaction.