bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Most 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

Photodetector 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

Extraordinary 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

Reconfigurable 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

We 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

Interest 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

Lead‐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

The 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

Paramagnetic 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

Bioorthogonal 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

Wir 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

Arachidonic‐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

Two‐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

The 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

A 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

Arynes 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

A 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

We 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.
Reprocessable Thermoset Soft Actuators
Authors: Yang Yang , Terentjev Eugene M. , Zhang Yubai , Chen Qiaomei , Zhao Yuan , Wei Yen , Ji Yan
Published: September 2019

Widely used traditional thermosets are good candidates for construction of 3D soft actuators because of their excellent stability; however, it is generally acknowledged that they cannot be reprocessed. The time–temperature equivalence principle enables reprocessing of traditional liquid crystalline epoxy thermosets (LCETs) into 3D soft actuators. Even though the transesterification reaction of LCETs is extremely slow, it is fast enough to induce a topology rearrangement and subsequent reprocessing when prolonging the transesterification time according to aforementioned principle. Therefore, LCETs can be aligned by a simple procedure. The alignment is quite stable at high temperature and remains after more than 1000 heating–cooling actuation cycles. The resulting 3D soft actuators are remouldable, reprogrammable, reconfigurable, weldable, self‐healable, recyclable, and stable, which is impossible for any traditional thermosets and is therefore a compelling advance in terms of the applications open to 3D soft actuators.
Ternary Monolithic ZnS/CdS/rGO Photomembrane with Desirable Charge Separation/Transfer Routes for Effective Photocatalytic and Photoelectrochemical Hydrogen Generation
Authors: Zhang Wanli , Huo Siying , Yang Siyuan , Zhong Yongming , Zhang Shengsen , Wang Hongqiang , Zhong Xinhua , Fang Yueping
Published: September 2019

Highly efficient and easy recyclable monolithic photocatalysts with ideal separation/transport route for photogenerated charge carriers are much desired. In this work, a ZnO seed‐induced growth approach is developed to fabricate a ternary monolithic photomembrane, that is, ZnS/CdS heterojunction nanorods in situ grow into the interspaces of multilayer reduced graphene oxide (rGO) sheets (denoted as ZnS/CdS/rGO). The monolithic ZnS/CdS/rGO photomembrane can serve as an efficient visible‐light photoactive membrane for photocatalytic (PC) or photoelectrochemical (PEC) hydrogen generation. The fast electron transport of 1D CdS nanorods, the excellent electronic conductivity of multilayer stacked rGO sheets, the intense visible‐light absorption of CdS, the unique hierarchical structure, and double heterojunctions (ZnS/CdS and CdS/rGO) efficiently boost the photogenerated electron‐hole pairs separation and transfer across the interfacial domain of the photomembrane under visible‐light irradiation. Furthermore, the superior stability and reusability of the photomembrane is achieved by the ideal process of photogenerated electron‐hole pair separation/transfer, i.e., holes transfer to ZnS and electrons transfer to rGO to inhibit CdS from photocorrosion.
Synthetic Strategies for (−)‐Cannabidiol and Its Structural Analogs
Authors: Jung Byunghyuck , Lee Jungkyu K. , Kim Jungnam , Kang Eunhye K. , Han Sang Yeong , Lee Hee‐Yoon , Choi Insung S.
Published: September 2019

(−)‐Cannabidiol ((−)‐CBD), a non‐psychoactive phytocannabinoid from Cannabis, and its structural analogs have received growing attention in recent years because of their potential therapeutic benefits, including neuroprotective, anti‐epileptic, anti‐inflammatory, anxiolytic, and anti‐cancer properties. (−)‐CBD and its analogs have been obtained mainly based on extraction from the natural source; however, the conventional extraction‐based methods have some drawbacks, such as poor quality control along with purification difficulty. Chemical‐synthetic strategies for (−)‐CBD could tackle these issues, and, additionally, generate novel (−)‐CBD analogs that exhibit advanced biological activities. This review concisely summarizes the historic and recent milestones in the synthetic strategies for (−)‐CBD and its analogs.
Functionalizing Reduced Graphene Oxide with Ru‐Organometallic Compounds as an Effective Strategy to Produce High‐Performance Pt Nanocatalysts for the Methanol Oxidation Reaction
Authors: Siller‐Ceniceros Adriana A. , Sánchez‐Castro Esther , Morales‐Acosta Diana , Torres‐Lubián José R. , Martínez‐Guerra Eduardo , Rodríguez‐Varela Javier
Published: September 2019

An efficient route to chemically functionalize reduced graphene oxide (rGO) with ruthenium organometallic compounds and the subsequent anchorage of Pt nanoparticles is reported. Two organometallic complexes, [(η6‐C6H5OCH2CH2OH) RuCl2]2 (Ru‐dim) and [(η6‐C6H4(CHMe2)Me)RuCl2]2 (Ru‐cym), as well as commercial RuCl3 ⋅ XH2O (Ru‐com) have been synthetized an used as functionalizing agents. By implementing a conventional polyol synthesis method, the Pt/rGORu‐dim, Pt/rGORu‐cym, Pt/rGORu‐com and Pt/rGO nanocatalysts have been synthetized. Characterization by XRD indicates that the presence of Ru leads to the formation of Pt−Ru alloyed phases due to overlapping of Pt fcc and Ru hcp reflections. When characterized for the methanol oxidation reaction (MOR) in acid media, Pt/rGORu‐dim reached a mass current density of 491.49 mA mgPt−1, higher than those generated by the other nanocatalysts. The results show that the functionalization of rGO with Ru‐dim remarkably increases the catalytic activity of Pt for the MOR, suggesting Pt−Ru metal−metal interactions that promotes the anodic reaction.
Selective Hydrogenation of Furfural in a Proton Exchange Membrane Reactor Using Hybrid Pd/Pd Black on Alumina
Authors: Carl Sarah , Waldrop Krysta , Pintauro Peter , Thompson Levi T. , Tarpeh William A.
Published: September 2019

Conventional thermocatalytic hydrogenation employs high temperatures and pressures and often exhibits low selectivity toward desired products. Electrochemical hydrogenation can reduce energy input by operating at ambient conditions and improving process control and selectivity; however, electrocatalysts face stability and conductivity limitations. To overcome these obstacles, we physically mixed a traditional electrocatalyst (Pd black) with a hydrogenation‐active metal (Pd) supported on a conventional metal oxide support (alumina, Al2O3) and investigated electrochemical hydrogenation of furfural, a model biomass compound. Experiments were conducted in a proton exchange membrane (PEM) reactor, in which synthesized electrocatalysts were used as cathodes. Catalysts with Pd black and varying loadings of Pd on Al2O3 were used to determine the impact of hydrogen spillover on electrocatalytic hydrogenation mechanisms, selectivity, and rates. Observed hydrogenation rates and selectivities were linked to structural and compositional properties of the catalyst mixtures. Of the Pd black cathodes tested, 5 wt % Pd/Al2O3 exhibited production rates as high as pure Pd black and higher selectivity towards completely hydrogenated products. Improved selectivity and rates were attributed to a synergistic interaction between Pd black and 5 wt % Pd/Al2O3 in which Pd/Al2O3 increased the number of active sites, while Pd black provided stable conductivity.
Synergistic Catalytic Effect of Ion Tunnels with Polar Dopants to Boost the Electrochemical Kinetics for High‐Performance Sulfur Cathodes
Authors: Zhang Jing , You Caiyin , Wang Jian , Guo Shaohua , Zhang Weihua , Yang Rong , Fu Ping
Published: September 2019

Rechargeable lithium−sulfur (Li−S) batteries with high areal capacity are hindered by the ion/electron pathway and sluggish reaction kinetics of sulfur species, resulting from high energy barriers. Inspired by the nature of biomass and efficient nutrition transfer, we present a high‐performance sulfur cathode based on nanocarbon tunnels with natural polar catalytic sites. The inherited tunnels can propel lithium‐ion transport across the interface to reach the active materials and the interior heteroatom dopants provide abundant catalytic sites to further reduce the energy barriers. The as‐fabricated sulfur cathode displays much higher rate performance of 565 mA h g−1 at 6 C and a low decay rates of 0.029 % per cycle for 2000 cycles at 3 C. Most importantly, a high initial areal capacity of 5.1 mA h cm−2 with enhanced loading up to 5.8 mg cm−2 at 1 C is achieved, corresponding to volumetric capacity of 638 A h L−1.
Use of Nitrogen‐Doped Carbon Nanodots for the Photocatalytic Fluoroalkylation of Organic Compounds
Authors: Rosso Cristian , Filippini Giacomo , Prato Maurizio
Published: September 2019

The use of amine‐rich N‐doped carbon nanodots (NCNDs) for the photochemical radical perfluoroalkylation of organic compounds is reported. This operationally simple approach occurs under mild conditions producing valuable new C−C bonds. The chemistry is driven by the ability of NCNDs to directly reach an electronically excited state upon light absorption, thereby successively triggering the formation of reactive radical species from simple perfluoroalkyl iodides. Preliminary mechanistic studies are also reported.
Spectroscopic Studies of the Magnetic Excitation and Spin‐Phonon Couplings in a Single‐Molecule Magnet
Authors: Stavretis Shelby E. , Moseley Duncan H. , Fei Fan , Cui Hui‐Hui , Cheng Yongqiang , Podlesnyak Andrey A. , Wang Xiaoping , Daemen Luke L. , Hoffmann Christina M. , Ozerov Mykhaylo , Lu Zhengguang , Thirunavukkuarasu Komalavalli , Smirnov Dmitry , Chang Tieyan , Chen Yu‐Sheng , Ramirez‐Cuesta Anibal J. , Chen Xue‐Tai , Xue Zi‐Ling (Ben)
Published: September 2019

Large separations between ground and excited magnetic states in single‐molecule magnets (SMMs) are desirable to reduce the likelihood of spin reversal in the molecules. Spin‐phonon coupling is a process leading to magnetic relaxation. Both the reversal and coupling, making SMMs lose magnetic moments, are undesirable. However, direct determination of large magnetic states separations (>45 cm−1) is challenging, and few detailed investigations of the spin‐phonon coupling have been conducted. The magnetic separation in [Co(12‐crown‐4)2](I3)2(12‐crown‐4) (1) is determined and its spin‐phonon coupling is probed by inelastic neutron scattering (INS) and far‐IR spectroscopy. INS, using oriented single crystals, shows a magnetic transition at 49.4(1.0) cm−1. Far‐IR reveals that the magnetic transition and nearby phonons are coupled, a rarely observed phenomenon, with spin‐phonon coupling constants of 1.7–2.5 cm−1. The current work spectroscopically determines the ground–excited magnetic states separation in an SMM and quantifies its spin‐phonon coupling, shedding light on the process causing magnetic relaxation.
When a Red–NIR‐Emissive Cs2[Mo6Br14] Interacts with an Active Diureasil–PEO Matrix: Design of Tunable and White‐Light‐Emitting Hybrid Material
Authors: Ferreira Molina Eduardo , Martins de Jesus Natana Aparecida , Paofai Serge , Hammer Peter , Amela‐Cortes Maria , Robin Malo , Cordier Stephane , Molard Yann
Published: September 2019

Hybrid materials that combine diureasil matrices and octahedral molybdenum clusters have been synthesized to design lead‐, cadmium‐ and rare‐earth‐free emitters for lighting or optoelectronic applications. This association leads to homogeneous and stable hybrids, for which the emission color can be tailored in the entire visible range, including white light; this is thanks to effective energy transfers from the host to the nanocluster.
Solid Solutions of Grimm–Sommerfeld Analogous Nitride Semiconductors II‐IV‐N2 (II=Mg, Mn, Zn; IV=Si, Ge): Ammonothermal Synthesis and DFT Calculations
Authors: Mallmann Mathias , Niklaus Robin , Rackl Tobias , Benz Maximilian , Chau Thanh G. , Johrendt Dirk , Minár Ján , Schnick Wolfgang
Published: September 2019

Grimm–Sommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa1−xIIbx)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach.
The Crystalline Sponge Method in Water
Authors: de Poel Wester , Tinnemans Paul , Duchateau Alexander L. L. , Honing Maarten , Rutjes Floris P. J. T. , Vlieg Elias , de Gelder René
Published: September 2019

The crystalline sponge method entails the elucidation of the (absolute) structure of molecules from a solution phase using single‐crystal X‐ray diffraction and eliminates the need for crystals of the target compound. An important limitation for the application of the crystalline sponge method is the instability of the available crystalline sponges that can act as host crystals. The host crystal that is most often used decomposes in protic or nucleophilic solvents, or when guest molecules with Lewis basic substituents are introduced. Here a new class of (water) stable host crystals based on f‐block metals is disclosed. It can be shown that these hosts not only increase the scope of the crystalline sponge method to a wider array of solvents and guests, but that they can even be applied to aqueous solutions containing hydrophilic guest molecules, thereby extending the crystalline sponge method to the important field of water‐based chemistry.
Methane Oxidation in the Water Column of Xiangxi Bay, Three Gorges Reservoir
Authors: Lei Dan , Liu Jia , Zhang Junwei , Lorke Andreas , Xiao Shangbin , Wang Yuchun , Wang Wei , Li Ye
Published: September 2019

Four field campaigns are carried out to quantify the methane (CH4) oxidation rate in Xiangxi Bay (XXB) of the Three Gorges Reservoir (TGR), China. The water depth of the sampling site varied from 13 to 30 m resulting from the water level fluctuation of the TGR. The CH4 oxidation rates are measured in situ as the decline of dissolved CH4 concentration versus time in incubated, and those rates. The CH4 oxidation rates range from 1.18 × 10−3 to 3.69 × 10−3 µmol L−1 h−1, with higher values and stronger variation during summer. A static floating chamber method is used to measure CH4 emitted to the atmosphere resulting in an annual mean flux of 4.79 µmol m−2 h−1. The CH4 emission rate is significantly negatively correlated with the water level. The results show that a large fraction of CH4 is consumed in the water column with a range of 28.97–55.90 µmol m−2 h−1, accounting for ≈69–98% of the total CH4 input into the water column, and more than 90% is consumed outside the summer, when the water level is lowest. Water depth, which is dominated by water level of the TGR, is a potentially important driver for CH4 oxidation and atmospheric emission in the tributary bay.
Single Crystal Growth of FeGa3 and FeGa3−xGex from High‐Temperature Solution Using the Czochralski Method
Authors: Bader Kristian , Gille Peter
Published: September 2019

Single crystal growth and characterization of the binary semiconducting compound FeGa3 and its Ge‐substitute FeGa3–xGex are reported. Whereas there have been several investigations on the thermoelectric properties based on small samples grown by the flux method, this study is the first approach using the Czochralski growth technique from well‐oriented single‐crystalline seeds. Problems and solutions of the growth of cm3‐size single crystals are discussed in detail. Ge segregation in FeGa3–xGex is described by a segregation coefficient lower than unity which leads to an axially increasing Ge content along the pulling direction. Consequences with respect to lattice parameter changes and thermoanalytic measurements are reported.
Hierarchical modeling strengthens evidence for density dependence in observational time series of population dynamics
Authors: Thibaut Loïc M. , Connolly Sean R.
Published: September 2019

The extent to which populations in nature are regulated by density‐dependent processes is unresolved. While experiments increasingly find evidence of strong density dependence, unmanipulated population time series yield much more ambiguous evidence of regulation, especially when accounting for effects of observation error. Here, we reexamine the evidence for density dependence in time series of population sizes in nature, by conducting an aggregate analysis of the populations in the Global Population Dynamics Database (GPDD). First, following the conventional approach, we fit a density‐dependent and a density‐independent variant of the Gompertz state‐space model to each time series. Then, we conduct an aggregate analysis of the entire database by considering two random‐effects density‐dependent models that leverage information across data sets. When individual time series are tested independently, we find very little evidence for density dependence. However, in the aggregate, we find very strong evidence for density dependence, even though, paradoxically, estimated strengths of density dependence for individual time series tend to be weaker than when each individual time series is analyzed independently. Furthermore, a hierarchical model that accounts for taxonomic variation in the strength of density dependence reveals that density dependence is consistently stronger in insects and fish than in birds and mammals. Our findings resolve apparent inconsistencies between observational and experimental studies of density dependence by revealing that the observational record does indeed contain strong support for the hypothesis that density dependence is widespread in nature.
Reporting the limits of detection and quantification for environmental DNA assays
Authors: Klymus Katy E. , Merkes Christopher M. , Allison Michael J. , Goldberg Caren S. , Helbing Caren C. , Hunter Margaret E. , Jackson Craig A. , Lance Richard F. , Mangan Anna M. , Monroe Emy M. , Piaggio Antoinette J. , Stokdyk Joel P. , Wilson Chris C. , Richter Catherine A.
Published: September 2019

Background

Environmental DNA (eDNA) analysis is increasingly being used to detect the presence and relative abundance of rare species, especially invasive or imperiled aquatic species. The rapid progress in the eDNA field has resulted in numerous studies impacting conservation and management actions. However, standardization of eDNA methods and reporting across the field is yet to be fully established, with one area being the calculation and interpretation of assay limit of detection (LOD) and limit of quantification (LOQ).

Aims

Here, we propose establishing consistent methods for determining and reporting of LOD and LOQ for single‐species quantitative PCR (qPCR) eDNA studies.

Materials & Methods/ Results

We utilize datasets from multiple cooperating laboratories to demonstrate both a discrete threshold approach and a curve‐fitting modeling approach for determining LODs and LOQs for eDNA qPCR assays. We also provide details of an R script developed and applied for the modeling method.

Discussion/Conclusions

Ultimately, standardization of how LOD and LOQ are determined, interpreted, and reported for eDNA assays will allow for more informed interpretation of assay results, more meaningful interlaboratory comparisons of experiments, and enhanced capacity for assessing the relative technical quality and performance of different eDNA qPCR assays.
Phenoxy‐Dialkoxy Borates as a New Class of Readily Prepared Preactivated Reagents for Base‐Free Cross‐Coupling
Authors: Paladino Marco , Boghi Michele , Hall Dennis G.
Published: September 2019

One of the most useful chemical transformations of organoboronic acids is the Suzuki–Miyaura cross‐coupling reaction. Although it has vast application, it possesses some limitations: boronic acids can be difficult to quantify accurately due to their tendency to form oligomeric anhydrides and they must be activated under basic conditions. To address these problems, a new class of boronic acid derivatives is described. Phenoxy‐dialkoxy borates are prepared under mild conditions and show good solubility in common organic solvents. These adducts can be used in base‐free metal‐catalysed cross‐coupling reactions, including orthogonal reactions with MIDA boronates and trifluoroborates.
Design of novel, simple, and inexpensive 3D printing‐based miniaturized electrochemical platform containing embedded disposable detector for analytical applications
Authors: de Moraes Natalia Canhete , da Silva Eiva Natiele Tiago , Petroni Jacqueline Marques , Ferreira Valdir Souza , Lucca Bruno Gabriel
Published: September 2019

This paper describes the development of a novel, simple, and inexpensive electrochemical device containing an integrated and disposable three‐electrode system for detection. The base of this platform consists on a PDMS structure containing microchannels which were prototyped using 3D‐printed molds. Pencil graphite leads were inserted into these microchannels and utilized as working, counter and reference electrodes in a novel design. Morphological analysis and electrochemical experiments with benchmark redox probes were carried out in order to evaluate the performance and characterize the miniaturized device proposed. Even using inexpensive materials and a simple fabrication protocol, the electrochemical platform developed provided good repeatability and reproducibility over a low cost (ca. $2 per device), acceptable lifetime (ca. 250 voltammetric runs) and extremely reduced consumption of samples and reagents (order of µL). As proof of concept, the analytical feasibility of the platform was investigated through the simultaneous determination of dopamine (DOPA) and acetaminophen (AC). The two analytes showed linear dependence on the concentration range from 1 to 15 µM and the LODs achieved were 0.21 µM for DOPA and 0.29 µM for AC. Moreover, the platform was successfully applied on the determination of DOPA and AC in spiked blood serum and urine samples. The results obtained with the device described here were better than some reports in literature that use more costly electrodic materials and complex modification steps for the detection of the same analytes.
Experimental study on the corrosion of a downhole string under flue gas injection conditions
Authors: Li Songyan , Zhang Kaiqiang , Wang Qun
Published: September 2019

Flue gas collection from steam generators and its utilization in enhanced oil recovery (EOR) can reduce CO2 emissions into the atmosphere and improve oil recovery efficiency. Under the environments of flue gas corrosion in oilfields, the effects of corrosion time, temperature, pressure, velocity, and concentrations of O2, SO2, H2O, and NaCl on corrosion rates of steels used for a downhole string were investigated through physical simulation experiments. The corrosion mechanisms were analyzed by component, and the morphology of the corrosion products tested by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). In the gas phase, the corrosion rates of X70, P110, and N80 notably increase with temperature and O2 concentration. The corrosion rates first increase rapidly with pressure from 1.0 to 3.0 MPa and then remain largely stable. Meanwhile, the corrosion rates of X70, P110, and N80 in the liquid phase first increase and then decrease with temperature and reach maximum values at 90°C. The corrosion rates of X70, P110, and N80 increase notably with velocity and the concentrations of O2, SO2, H2O, and NaCl. The corrosion rate of 13Cr is considerably lower than those of N80, P110, and X70, which shows good corrosion resistance performance. To reduce the flue gas corrosion of a downhole string, the relative humidity of the flue gas should be lower than 0.7, the temperature of the flue gas in the wellbore should avoid the range between 80 and 100°C, the excess air coefficient of the boiler should be kept at a reasonable value to reduce the O2 content in the flue gas, and the flue gas should not be coinjected into wellbores with brine. The injection of flue gas is technically feasible considering the corrosion of downhole string.
TLRs toll for Tregs
Authors: Aksoy Ezra
Published: September 2019

Discussion on TLR3 triggering in CD4 T cells induces IFN beta and IL10-producing iTregs that suppress food allergy.
Edge Distance‐based Topological Indices of Strength‐weighted Graphs and their Application to Coronoid Systems, Carbon Nanocones and SiO2 Nanostructures
Authors: Arockiaraj Micheal , Klavžar Sandi , Clement Joseph , Mushtaq Shagufa , Balasubramanian Krishnan
Published: September 2019

The edge‐Wiener index is conceived in analogous to the traditional Wiener index and it is defined as the sum of distances between all pairs of edges of a graph G. In the recent years, it has received considerable attention for determining the variations of its computation. Motivated by the method of computation of the traditional Wiener index based on canonical metric representation, we present the techniques to compute the edge‐Wiener and vertex‐edge‐Wiener indices of G by dissecting the original graph G into smaller strength‐weighted quotient graphs with respect to Djoković‐Winkler relation. These techniques have been applied to compute the exact analytic expressions for the edge‐Wiener and vertex‐edge‐Wiener indices of coronoid systems, carbon nanocones and SiO2 nanostructures. In addition, we have reduced these techniques to the subdivision of partial cubes and applied to the circumcoronene series of benzenoid systems.