bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyurethane End‐Capped by Tetramethylpyrazine‐Nitrone for Promoting Endothelialization Under Oxidative Stress
Authors: Qu Baoliu , Yuan Liguang , Yang Lei , Li Jinge , Lv Hongying , Yang Xiaoniu 
Published: September 2019

AbstractThrombus and restenosis are two main factors that cause the failure of vascular implants. Constructing a functional and confluent layer of endothelial cells (ECs) is considered an ideal method to prevent these problems. However, oxidative stress induced by the disease and implantation can damage ECs and hinder the endothelialization of implants. Thus, developing biomaterials that can protect ECs adhesion and proliferation from oxidative stress is urgently needed for the rapid endothelialization of vascular implants. In this work, a novel polyurethane (PU‐TBN) is synthesized by employing tetramethylpyrazine‐nitrone (TBN) as end‐group to endow polymers with dual functions of antioxidant activity and promoting endothelialization. Common PU without TBN is also prepared to be control. Compared to PU, PU‐TBN significantly promotes human umbilical vein endothelial cells (HUVECs) adhesion and proliferation, where cells spread well and a confluent endothelial layer is formed. PU‐TBN also shows obvious free radical scavenging activity, and thus effectively attenuates oxidative stress to protect HUVECs from oxidative apoptosis. Moreover, PU‐TBN exhibits enhanced antiplatelets effect, excellent biocompatibility, and similar mechanical properties to PU. These characteristics can endow PU‐TBN with great potential to be used as vascular implants or coatings of other materials for rapid endothelialization under complex oxidative stress environment.
Self‐Unfolding Flexible Microelectrode Arrays Based on Shape Memory Polymers
Authors: Wang Juan , Zhao Qilong , Wang Yunlong , Zeng Qi , Wu Tianzhun , Du Xuemin 
Published: September 2019

AbstractMost of the current concepts for a visual prosthesis are based on neuronal electric stimulation. However, existing visual prostheses confront several challenges in electrodes that limit the effectiveness of stimulation. First, there is an inherent conflict between the needs of minimally invasive implantation for minimizing traumas and the requirements of implanted electrodes with large areas for obtaining wide field and high‐resolution vision. Second, the mechanical and geometrical mismatches between implanted electrodes and retina tissues also affect the effectiveness of stimulation. To address these challenges, flexible microelectrode arrays (fMEAs) with expanded areas, high‐density electrodes, and unique self‐unfolding capabilities are here reported, which will be feasible for minimally invasive implantation and accommodate large strain and geometrical curvature for potentially improving both the visual field and visual acuity. To obtain the flexible nature and programmable self‐unfolding property, the fMEAs are formulated based on a shape memory polymer with appropriate physicochemical properties. At the physiological temperature (37 °C), programmable shape deformation from a tubular shape to a unfolded film shape is enabled by the fMEAs with a large area (10 × 10 mm2) and high‐density electrodes (126 channels), implying their superior potential for minimally invasive implantation, excellent shape adaption to retinal tissues, and high‐efficiency stimulation.
Ultracompact Camera Pixel with Integrated Plasmonic Color Filters
Authors: Panchenko Evgeniy , Wesemann Lukas , Gómez Daniel E. , James Timothy D. , Davis Timothy J. , Roberts Ann 
Published: September 2019

AbstractPhotodetector size imposes a fundamental limit on the amount of information that can be recorded by an image sensor. Compact, high‐resolution sensors are generally preferred for portable electronic devices such as mobile phones and digital cameras, and as a result, a significant effort has been invested in improving the image quality provided by small‐area image sensors. Reducing photodetector size, however, still faces challenges in implementation requiring improvements in current technology to meet the demand for ultracompact imaging systems such as cameras. An issue with a decrease in size is associated with photodetectors utilizing color filters. In most commonly used camera designs these filters are made of dyes or pigments and incompatible with the complementary metal‐oxide‐semiconductor fabrication process. They are, therefore, fabricated in two different technological processes and require subsequent alignment. As the pixel size decreases, the alignment of these layers becomes challenging. Furthermore, dye‐based filters need to have a thickness of the order of micrometers to ensure sufficient absorption. Here a compact, low‐cost color sensor is proposed and experimentally demonstrated utilizing monolithically integrated plasmonic antennas that have a nanoscale thickness and are fabricated in the same technological process with photodetector matrix.
Allogeneic mesenchymal stem cell therapy: A regenerative medicine approach to geroscience
Authors: Oliva Anthony A. , McClain‐Moss Lisa , Pena Andrea , Drouillard Amy , Hare Joshua M. 
Published: September 2019

AbstractExtraordinary advances in medicine and public health have contributed to increasing life expectancy worldwide. However, health span—“healthy aging”—has paradoxically lagged to parallel this increase. Consequently, aging‐associated illnesses, such as Alzheimer's disease and aging frailty, are having a growing impact on patients, their families, and entire health‐care systems. Typically, such disorders have been treated as isolated disease entities. However, the inextricable links between aging‐associated disorders and the aging process itself have become increasingly recognized, leading to formation of the field of geroscience. The geroscience concept is that treating the aging process itself should lead to treatment and prevention of aging‐related disorders. However, the aging process is complex, dictated by highly interrelated pleiotropic processes. As such, therapeutics with pleiotropic mechanisms of action (either alone, or as part of combinatorial strategies) will be required for preventing and treating both aging and related disorders. Mesenchymal stem cells (MSCs) have multiple mechanisms of action that make these highly promising geroscience therapeutic candidates. These cells have a high safety profile for clinical use, are amenable to allogeneic use since tissue‐type matching is not required, and can have sustained activity after transplantation. Herein, we review preclinical and clinical data supporting the utility of allogeneic MSCs as a geroscience therapeutic candidate.
Rational Design of pH‐Responsive DNA Motifs with General Sequence Compatibility
Authors: Fu Wenhao , Tang Linlin , Wei Gaohui , Fang Liang , Zeng Jie , Zhan Renjie , Liu Xuemei , Zuo Hua , Huang Cheng Zhi , Mao Chengde 
Published: September 2019

AbstractReconfigurable molecular events are key to molecular machines. In response to external cues, molecular machines rearrange/change their structures to perform certain functions. Such machines exist in nature, for example cell surface receptors, and have been artificially engineered. To be able to build sophisticated and efficient molecular machines for an increasing range of applications, constant efforts have been devoted to developing new mechanisms of controllable structural reconfiguration. Herein, we report a general design principle for pH‐responsive DNA motifs for general DNA sequences (not limited to triplex or i‐motif forming sequences). We have thoroughly characterized such DNA motifs by polyacrylamide gel electrophoresis (PAGE) and fluorescence spectroscopy and demonstrated their applications in dynamic DNA nanotechnology. We expect that it will greatly facilitate the development of DNA nanomachines, biosensing/bioimaging, drug delivery, etc.
Spatially Resolved Genetic Analysis of Tissue Sections Enabled by Microscale Flow Confinement Retrieval and Isotachophoretic Purification
Authors: van Kooten Xander F. , Petrini Lorenzo F. T. , Kashyap Aditya , Voith von Voithenberg Lena , Bercovici Moran , Kaigala Govind V. 
Published: September 2019

AbstractWe have developed a method for spatially resolved genetic analysis of formalin‐fixed paraffin‐embedded (FFPE) cell block and tissue sections. This method involves local sampling using hydrodynamic flow confinement of a lysis buffer, followed by electrokinetic purification of nucleic acids from the sampled lysate. We characterized the method by locally sampling an array of points with a circa 200 μm diameter footprint, enabling the detection of single KRAS and BRAF point mutations in small populations of RKO and MCF‐7 FFPE cell blocks. To illustrate the utility of this approach for genetic analysis, we demonstrate spatially resolved genotyping of FFPE sections of human breast invasive ductal carcinoma.
Halogen Vacancies Enable Ligand‐Assisted Self‐Assembly of Perovskite Quantum Dots into Nanowires
Authors: Pan Jun , Li Xiyan , Gong Xiwen , Yin Jun , Zhou Dianli , Sinatra Lutfan , Huang Renwu , Liu Jiakai , Chen Jie , Dursun Ibrahim , El‐Zohry Ahmed M. , Saidaminov Makhsud I. , Sun Hong‐Tao , Mohammed Omar F. , Ye Changhui , Sargent Edward H. , Bakr Osman M. 
Published: September 2019

AbstractInterest has been growing in defects of halide perovskites in view of their intimate connection with key material optoelectronic properties. In perovskite quantum dots (PQDs), the influence of defects is even more apparent than in their bulk counterparts. By combining experiment and theory, we report herein a halide‐vacancy‐driven, ligand‐directed self‐assembly process of CsPbBr3 PQDs. With the assistance of oleic acid and didodecyldimethylammonium sulfide, surface‐Br‐vacancy‐rich CsPbBr3 PQDs self‐assemble into nanowires (NWs) that are 20–60 nm in width and several millimeters in length. The NWs exhibit a sharp photoluminescence profile (≈18 nm full‐width at‐half‐maximum) that peaks at 525 nm. Our findings provide insight into the defect‐correlated dynamics of PQDs and defect‐assisted fabrication of perovskite materials and devices.
Lead‐Free Sodium–Indium Double Perovskite Nanocrystals through Doping Silver Cations for Bright Yellow Emission
Authors: Han Peigeng , Mao Xin , Yang Songqiu , Zhang Fei , Yang Bin , Wei Donghui , Deng Weiqiao , Han Keli 
Published: September 2019

AbstractLead‐free halide perovskite nanocrystals (NCs) have drawn wide attention for solving the problem of lead perovskites toxicity and instability. Herein, we synthesize the direct band gap double perovskites undoped and Ag‐doped Cs2NaInCl6 NCs by variable temperature hot injection. The Cs2NaInCl6 NCs have little photoluminescence because of dark self‐trapped excitons (STEs). The dark STEs can be converted into bright STEs by doping with Ag+ to produce a bright yellow emission, with the highest photoluminescence quantum efficiency of 31.1 %. The dark STEs has been directly detected experimentally by ultrafast transient absorption (TA) techniques. The dynamics mechanism is further studied. In addition, the Ag‐doped NCs show better stability than the undoped ones. This result provides a new way to enhance the optical properties of lead‐free perovskites NCs for high‐performance light emitters.
The Critical Role of Reductive Steps in the Nickel‐Catalyzed Hydrogenolysis and Hydrolysis of Aryl Ether C−O Bonds
Authors: Wang Meng , Zhao Yuntao , Mei Donghai , Bullock R. Morris , Gutiérrez Oliver Y. , Camaioni Donald M. , Lercher Johannes A. 
Published: September 2019

AbstractThe hydrogenolysis of the aromatic C−O bond in aryl ethers catalyzed by Ni was studied in decalin and water. Observations of a significant kinetic isotope effect (kH/kD=5.7) for the reactions of diphenyl ether under H2 and D2 atmosphere and a positive dependence of the rate on H2 chemical potential in decalin indicate that addition of H to the aromatic ring is involved in the rate‐limiting step. All kinetic evidence points to the fact that H addition occurs concerted with C−O bond scission. DFT calculations also suggest a route consistent with these observations involving hydrogen atom addition to the ipso position of the phenyl ring concerted with C−O scission. Hydrogenolysis initiated by H addition in water is more selective (ca. 75 %) than reactions in decalin (ca. 30 %).
Metal‐Chelated Polymer Nanodiscs for NMR Studies
Authors: Hardin Nathaniel Z. , Kocman Vojč , Di Mauro Giacomo M. , Ravula Thirupathi , Ramamoorthy Ayyalusamy 
Published: September 2019

AbstractParamagnetic relaxation enhancement (PRE) is commonly used to speed up spin lattice relaxation time (T1) for rapid data acquisition in NMR structural studies. Consequently, there is significant interest in novel paramagnetic labels for enhanced NMR studies on biomolecules. Herein, we report the synthesis and characterization of a modified poly(styrene‐co‐maleic acid) polymer which forms nanodiscs while showing the ability to chelate metal ions. Cu2+‐chelated nanodiscs are demonstrated to reduce the T1 of protons for both polymer and lipid‐nanodisc components. The chelated nanodiscs also decrease the proton T1 values for a water‐soluble DNA G‐quadruplex. These results suggest that polymer nanodiscs functionalized with paramagnetic tags can be used to speed‐up data acquisition from lipid bilayer samples and also to provide structural information from water‐soluble biomolecules.
Enzyme‐Mediated Endogenous and Bioorthogonal Control of a DNAzyme Fluorescent Sensor for Imaging Metal Ions in Living Cells
Authors: Lin Yao , Yang Zhenglin , Lake Ryan J. , Zheng Chengbin , Lu Yi 
Published: September 2019

AbstractBioorthogonal control of metal‐ion sensors for imaging metal ions in living cells is important for understanding the distribution and fluctuation of metal ions. Reported here is the endogenous and bioorthogonal activation of a DNAzyme fluorescent sensor containing an 18‐base pair recognition site of a homing endonuclease (I‐SceI), which is found by chance only once in 7×1010 bp of genomic sequences, and can thus form a near bioorthogonal pair with I‐SceI for DNAzyme activation with minimal effect on living cells. Once I‐SceI is expressed inside cells, it cleaves at the recognition site, allowing the DNAzyme to adopt its active conformation. The activated DNAzyme sensor is then able to specifically catalyze cleavage of a substrate strand in the presence of Mg2+ to release the fluorophore‐labeled DNA fragment and produce a fluorescent turn‐on signal for Mg2+. Thus I‐SceI bioorthogonally activates the 10–23 DNAzyme for imaging of Mg2+ in HeLa cells.
Ein terminaler Nitriliminkomplex des Eisens: Zugang zum terminalen Nitrid durch Spaltung einer Diazo‐N‐N‐Bindung
Authors: Aghazada Sadig , Miehlich Matthias , Messelberger Julian , Heinemann Frank W. , Munz Dominik , Meyer Karsten 
Published: September 2019

AbstractWir stellen eine neue Methode zur Synthese terminaler Nitridokomplexe über den Weg der N‐N‐Bindungsspaltung von Trimethylsilyldiazomethan vor. Mithilfe des Lithiumsalzes des Trimethylsilyldiazomethans wurde ein seltener terminaler Übergangsmetallkomplex des Nitrilimins mit teilweise besetzten d‐Orbitalen erhalten. Dieser Eisenkomplex 2 wurde durch CHN‐Verbrennungsanalyse, 1H‐ und 13C‐NMR‐Spektroskopie, Einkristall‐Röntgenstrukturanalyse, SQUID‐Magnetometrie, 57Fe‐Mößbauer‐Spektroskopie und quantenchemische Rechnungen charakterisiert. Die Ergebnisse belegen eine high‐spin d 6 (S=2)‐Elektronenkonfiguration des Komplexes und eine Allenstruktur des Nitriliminliganden. Die Reduktion von 2 führt dazu, dass der Nitriliminligand dissoziiert und sich der Eisen(I)‐Komplex 3 bildet. Dieser wurde durch CHN‐Verbrennungsanalyse, 1H‐NMR‐Spektroskopie und Einkristall‐Röntgenstrukturanalyse charakterisiert. Die Reaktion von 2 mit Fluoridsalzen ergibt durch N‐N‐Bindungsspaltung quantitativ den diamagnetischen FeIV‐Nitridokomplex 4, bei gleichzeitiger Bildung von Fluortrimethylsilan und eines Cyanidanions.
15‐Hydroperoxy‐PGE2: Intermediate in Mammalian and Algal Prostaglandin Biosynthesis
Authors: Jagusch Hans , Werner Markus , Werz Oliver , Pohnert Georg 
Published: September 2019

AbstractArachidonic‐acid‐derived prostaglandins (PGs), specifically PGE2, play a central role in inflammation and numerous immunological reactions. The enzymes of PGE2 biosynthesis are important pharmacological targets for anti‐inflammatory drugs. Besides mammals, certain edible marine algae possess a comprehensive repertoire of bioactive arachidonic‐acid‐derived oxylipins including PGs that may account for food poisoning. Described here is the analysis of PGE2 biosynthesis in the red macroalga Gracilaria vermiculophylla that led to the identification of 15‐hydroperoxy‐PGE2, a novel precursor of PGE2 and 15‐keto‐PGE2. Interestingly, this novel precursor is also produced in human macrophages where it represents a key metabolite in an alternative biosynthetic PGE2 pathway in addition to the well‐established arachidonic acid‐PGG2‐PGH2‐PGE2 route. This alternative pathway of mammalian PGE2 biosynthesis may open novel opportunities to intervene with inflammation‐related diseases.
Carboamination of Unactivated Alkenes through Three‐Component Radical Conjugate Addition
Authors: Jiang Heng , Seidler Gesa , Studer Armido 
Published: September 2019

AbstractTwo‐component Giese type radical additions are highly practical and established reactions. Herein, three‐component radical conjugate additions of unactivated alkenes to Michael acceptors are reported. Amidyl radicals, oxidatively generated from α‐amido oxy acids using redox catalysis, act as the third reaction component which add to the unactivated alkenes. The adduct radicals engage in Giese type additions to Michael acceptors to provide, after reduction, the three‐component products in an overall alkene carboamination reaction. Transformations which can be conducted under practical mild conditions feature high functional group tolerance and broad substrate scope.
Sn2B5O9Cl: A Material with Large Birefringence Enhancement Activated Prepared via Alkaline‐Earth‐Metal Substitution by Tin
Authors: Guo Jingyu , Tudi Abudukadi , Han Shujuan , Yang Zhihua , Pan Shilie 
Published: September 2019

AbstractThe excellent birefringent materials are needed for optical systems. Herein, we reported a new compound, the first tin borate chloride, Sn2B5O9Cl (SBOC) with a large birefringence (0.168 at 546 nm) measured by the polarizing microscope. Its birefringence is 16 times that of the isostructural Ba2B5O9Cl (BBOC) compound (0.010@ at 546 nm). The results show that the birefringence enhancement originates mainly from the Sn2+ polyhedra. We propose that the birefringence can be enlarged by substituting the alkaline‐earth metal cation by the Sn2+ cation in the isostructural borate with small birefringence. This strategy will guide the discovery of large birefringent materials in the future.
Lithium‐Salt Mediated Synthesis of a Covalent Triazine Framework for Highly Stable Lithium Metal Batteries
Authors: Zhou Tianhong , Zhao Yan , Choi Jang Wook , Coskun Ali 
Published: September 2019

AbstractA new strategy for the synthesis of a covalent triazine framework (CTF‐1) was introduced based on the cyclotrimerization reaction of 1,4‐dicyanobenzene using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) under ionothermal conditions. LiTFSI not only served as a catalyst, but also facilitated the in situ generation and homogeneous distribution of LiF particles across the framework. The hierarchical structure resulting upon integration of CTF‐LiF onto an airlaid‐paper (AP) offered unique features for lithium metal anodes, such as lithiophilicity from CTF, interface stabilization from LiF, and sufficient lithium storage space from AP. Based on this synergistic effect, the AP‐CTF‐LiF anode exhibited stable cycling performance even at a current density of 10 mA cm−2.
Uncovering the Neglected Similarities of Arynes and Donor–Acceptor Cyclopropanes
Authors: Werz Daniel B. , Biju Akkattu T. 
Published: September 2019

AbstractArynes and donor–acceptor (D–A) cyclopropanes are two classes of strained systems having the potential for numerous applications in organic synthesis. The last two decades have witnessed a renaissance of interest in the chemistry of these species primarily because of the mild and robust methods for their generation or activation. Commonly, arynes as easily polarizable systems result in 1,2‐disubstitution, whereas D‐A cyclopropanes as polarized systems lead to 1,3‐bisfunctionalization thereby showing striking similarities. Transformations with 1,2‐ and 1,3‐dipoles afford cyclic structures. With arynes, emerging four‐membered rings as intermediates might react further, whereas the analogous five‐membered rings obtained from D–A cyclopropanes are most often the final products. However, there are a few cases where these intermediates behave surprisingly differently. This Minireview highlights the parallels in reactivity between arynes and D–A cyclopropanes thereby shedding light on the neglected similarities of these two reactive species.
A Terminal Iron Nitrilimine Complex: Accessing the Terminal Nitride through Diazo N−N Bond Cleavage
Authors: Aghazada Sadig , Miehlich Matthias , Messelberger Julian , Heinemann Frank W. , Munz Dominik , Meyer Karsten 
Published: September 2019

AbstractA novel method for the N−N bond cleavage of trimethylsilyl diazomethane is reported for the synthesis of terminal nitride complexes. The lithium salt of trimethylsilyl diazomethane was used to generate a rare terminal nitrilimine transition metal complex with partially occupied d‐orbitals. This iron complex 2 was characterized by CHN combustion analysis, 1H and 13C NMR spectroscopic analysis, single‐crystal X‐ray crystallography, SQUID magnetometry, 57Fe Mössbauer spectroscopy, and computational analysis. The combined results suggest a high‐spin d 6 (S=2) electronic configuration and an allenic structure of the nitrilimine ligand. Reduction of 2 results in release of the nitrilimine ligand and formation of the iron(I) complex 3, which was characterized by CHN combustion analysis, 1H NMR spectroscopic analysis, and single‐crystal X‐ray crystallography. Treatment of 2 with fluoride salts quantitatively yields the diamagnetic FeIV nitride complex 4, with concomitant formation of cyanide and trimethylsilyl fluoride through N−N bond cleavage.
Photochemical C−H Hydroxyalkylation of Quinolines and Isoquinolines
Authors: Bieszczad Bartosz , Perego Luca Alessandro , Melchiorre Paolo 
Published: September 2019

AbstractWe report herein a visible light‐mediated C−H hydroxyalkylation of quinolines and isoquinolines that proceeds via a radical path. The process exploits the excited‐state reactivity of 4‐acyl‐1,4‐dihydropyridines, which can readily generate acyl radicals upon blue light absorption. By avoiding the need for external oxidants, this radical‐generating strategy enables a departure from the classical, oxidative Minisci‐type pattern and unlocks a unique reactivity, leading to hydroxyalkylated heteroarenes. Mechanistic investigations provide evidence that a radical‐mediated spin‐center shift is the key step of the process. The method's mild reaction conditions and high functional group tolerance accounted for the late‐stage functionalization of active pharmaceutical ingredients and natural products.