bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic Effect of Covalent Bonding and Physical Encapsulation of Sulfur in the Pores of a Microporous COF to Improve Cycling Performance in Li‐S Batteries
Authors: Royuela Sergio , Almarza Joaquín , Mancheño María J. , Pérez‐Flores Juan C. , Michel Enrique G. , Ramos María M. , Zamora Félix , Ocón Pilar , Segura José L. 
Published: July 2019

AbstractLithium‐sulfur batteries stands out as a promising technology for energy storage owing to a combination of favorable characteristics including a high theoretical gravimetric capacity, energy density, inexpensive character, and environmental benignity. Covalent organic frameworks (COFs) are a rapidly developing family of functional nanostructures which combine porosity and crystallinity, and which have been already used in these kinds of batteries to build sulfur electrodes, by embedding sulfur into porous COFs in order to enhance cycle lifetimes. In this contribution, this is taken one step forward and a COF endowed with vinyl groups is used, in order to graft sulfur to the COF skeleton through inverse vulcanization. The main aim of the article is to show the synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of the COF in order to alleviate the fatal redox shuttling process, to improve the cycling performance, and to provide faster ion diffusion pathways. In addition, it is shown how the material with covalently‐bound S provides better electrochemical performance under demanding and/or changeable charge conditions than a parent analogue material with sulfur physically confined, but without covalent linkage.
Probing 2H‐Indazoles as Templates for SGK1, Tie2, and SRC Kinase Inhibitors
Authors: Schoene Jens , Gazzi Thais , Lindemann Peter , Christmann Mathias , Volkamer Andrea , Nazaré Marc 
Published: July 2019

AbstractThe broader and systematic application of a novel scaffold is often hampered by the unavailability of a short and reliable synthetic access. We investigated a new strategy for the design and synthesis of an array of N2‐substituted aza‐2H‐indazole derivatives as potential kinase inhibitors. Guided by a rational ligand alignment approach to qualify the so‐far underrepresented aza‐2H‐indazole scaffold, indazoles were connected at the N2 position with a phenyl spacer and an arylsulfonamide or amide linkage. Initial profiling against a panel of 30 kinases confirmed the in silico predicted selectivity bias. A synthesized focused library of 52 different aza‐2H‐indazole derivatives showed good initial selective inhibition against SGK1, Tie2, and SRC kinases, with the best representatives having IC50 values in the range of 500 nm. In a comparative computational study, these data were analyzed and rationalized in light of docking studies.
A new replica placement mechanism for mobile media streaming in edge computing
Authors: Tang Yayuan , Wang Hao , Guo Kehua , Luo Tao , Chi Tao 
Published: July 2019

SummaryWith the advent of the Internet of things era, cloud computing platforms will face the challenges of massive equipment requirements for access, massive data, insufficient bandwidth, and high power consumption. Edge computing, as a new technology, makes it possible to stream media over the edge network. However, many problems related to file sharing among edge nodes and to the files provided by cloud servers exist. We propose a novel replica placement strategy for mobile media streaming in edge computing (RPME) to address the aforementioned problem. First, we introduce a multilevel replica placement model in the RPME. In the RPME, we acquire the user information and the user‐item rating matrix when the user requests the media data. At the server, we cluster the users according the user information, update the user‐item rating matrix, and then generate a replica recommendation sequence. For when the server submits the replica recommendation sequence to the edge node considering the constraints of the edge node storage capacity and the limitations on the service capacity of the requested replica, we propose an effective replica placement mechanism in the RPME. To show the benefits of the RPME, we also present several experiments to prove its validity.
Kinetic Control over Morphology of Nanoporous Graphene on Surface
Authors: Huang Jianmin , Jia Hongxing , Wang Tao , Feng Lin , Du Pingwu , Zhu Junfa 
Published: July 2019

AbstractOn‐surface synthesis of high‐quality nanoporous graphene (NPG) for application in nanotechnology and nanodevices remains challenging. Rational design of molecular precursors and proper kinetic control over the reaction process are the two key factors to tune the synthesis. Herein, we report a detailed study of the coupling reactions of a planar halogen‐substituted nanographene molecular precursor, hexaiodo‐peri‐hexabenzocoronene (I6‐HBC), on the Au(111) surface in the synthesis of NPG. The influence of three basic kinetic processes – molecular adsorption, migration, and coupling – on the synthesis was investigated. The results show that the HBC molecules deposited at low temperature predominantly desorb from the Au(111) surface during the annealing process, whereas depositing the precursor molecules onto a hot surface (700 K) can lead to the formation of NPG. However, at such a high surface temperature, simultaneous intermolecular dehydrogenative coupling between HBC monomers can hinder the ordered growth of NPG through Ullmann coupling. Moreover, the deposition rate of the precursors greatly influences the growth morphology of the NPG nanostructures.
Design of Multi‐Metallic‐Based Electrocatalysts for Enhanced Water Oxidation
Authors: Bo Xin , Dastafkan Kamran , Zhao Chuan 
Published: July 2019

AbstractElectrochemical water splitting by renewable energy resources is an efficient and green approach for hydrogen gas production. However, the anodic oxygen evolution reaction (OER) largely impedes the industrial application due to its sluggish four‐electron‐transition kinetics. Although various materials have been developed to accelerate the OER rate, still some issues should be addressed to meet the industrial demand: (i) considerable 200–300 mV overpotential as extra onset energy input, (ii) limited survival and performance in acidic electrolyte for the majority of oxide/hydroxide composite materials, (iii) unsatisfying long‐term durability and (iv) the need for facile and scalable preparation methods. Here, we emphasize on multi‐metallic composites with enhanced OER activity based on both precious and nonprecious elements that outperform the unary and binary composites. The regulation effect from multi‐metal incorporation is also summarized systematically: (i) introducing foreign metal atoms to the host material boosts the physical properties such as conductivity, surface area, defect density, morphology, wettability, etc., (ii) metal doping can synergistically regulate the electronic features of the host material, e. g. oxygen vacancy, eg orbit filling, coordinative number and covalence state, which can optimize the absorption/desorption energy of the M−O intermediate, (iii) chaotic impact from the added atoms twists the catalyst lattice into a more aggressive and higher energy state, which is more feasible to transform to an active intermediate with lower required energy supply. This review aims to provide a practical approach to further improve the OER performance via multi‐metallic‐based catalysts.
Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst
Authors: Gregori Bernhard J. , Schwarzhuber Felix , Pöllath Simon , Zweck Josef , Fritsch Lorena , Schoch Roland , Bauer Matthias , Jacobi von Wangelin Axel 
Published: July 2019

AbstractThe stereoselective hydrogenation of alkynes constitutes one of the key approaches for the construction of stereodefined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. This study concerns a simple catalyst comprised of the commercial chemicals iron(II) acetylacetonate and diisobutylaluminum hydride, which enables the Z‐selective semihydrogenation of alkynes under near ambient conditions (1–3 bar H2, 30 °C, 5 mol % [Fe]). Neither an elaborate catalyst preparation nor addition of ligands is required. Mechanistic studies (kinetic poisoning, X‐ray absorption spectroscopy, TEM) strongly indicate the operation of small iron clusters and particle catalysts.
Ultralow power voltage reference circuit for implantable devices in standard CMOS technology
Authors: Pereira‐Rial Óscar , López Paula , Carrillo Juan M. , Brea Víctor M. , Cabello Diego 
Published: July 2019

SummaryAn ultralow power CMOS voltage reference for body implantable devices is presented in this paper. The circuit core consists of only regular threshold voltage PMOS transistors, thus leading to a very reduced output voltage dispersion, defined as σ/μ, and extremely low power consumption. A mathematical model of the generated reference voltage was obtained by solving circuit equations, and its numerical solution has been validated by extensive electrical simulations using a commercial circuit simulator. The proposed solution incorporates a passive RC low‐pass filter, to enhance power supply rejection (PSR) over a wide frequency range, and a speed‐up section, to accelerate the switching‐on of the circuit. The prototype was implemented in 0.18 μm standard CMOS technology and is able to operate with supply voltages ranging from 0.7 to 1.8 V providing a measured output voltage value of 584.2 mV at the target temperature of 36° C. The measured σ/μ dispersion of the reference voltage generated is 0.65% without the need of trimming. At the minimum supply of 0.7 V, the experimental power consumption is 64.5 pW, while the measured PSR is kept below –60 dB from DC up to the MHz frequency range.
Wetland environmental bioreactor system contributes to the decomposition of cellulose
Authors: Liu Wen , Tanimura Aya , Nagara Yumi , Watanabe Tetsuhiro , Maegawa Shingo , Toyohara Haruhiko 
Published: July 2019

AbstractRecently, numerous species of aquatic invertebrates inhabiting wetlands have been shown to possess endogenous cellulase, following the discovery that termites have cellulase genes encoded in their own genome rather than relying on symbiotic bacteria for decomposing cellulose. Wetlands have been empirically shown to play an important role in the decomposition of land‐originating hard‐to‐degrade polysaccharides such as cellulose. However, the mechanism that connects the cellulase producer and the wetlands remains unknown, which makes it very difficult to evaluate the ecological function of wetlands. Here we found that a macrobenthic bivalve, Corbicula japonica, secretes its cellulase to the wetland sediment. Secreted cellulases are immobilized in the components of the sediment. Moreover, adding cellulose or glucose to C. japonica could trigger its cellulase secretion level. These findings suggest a novel wetland cellulose decomposition mechanism. The decomposition ability of wetlands was previously ascribed only to microbes and/or invertebrates that contain cellulases. Our findings suggest that benthic animals supply wetlands with their enzymes as decomposition agents, while wetland sediments serve as immobilization scaffolds for the enzymes. This system, which was named by us an “environmental bioreactor system,” could provide a key function in wetlands.
Allelopathic effects of volatile organic compounds released from Pinus halepensis needles and roots
Authors: Santonja Mathieu , Bousquet‐Mélou Anne , Greff Stéphane , Ormeño Elena , Fernandez Catherine 
Published: July 2019

AbstractThe Mediterranean region is recognized as a global biodiversity hotspot. However, over the last decades, the cessation of traditional farming in the north part of the Mediterranean basin has given way to strong afforestation leading to occurrence of abandoned agricultural lands colonized by pioneer expansionist species like Pinus halepensis. This pine species is known to synthesize a wide range of secondary metabolites, and previous studies have demonstrated strong allelopathic potentialities of its needle and root leachates. Pinus halepensis is also recognized to release significant amounts of volatile organic compounds (VOC) with potential allelopathic effects that have never been investigated. In this context, the objectives of the present study were to improve our knowledge about the VOC released from P. halepensis needles and roots, determine if these VOC affect the seed germination and root growth of two herbaceous target species (Lactuca sativa and Linum strictum), and evaluate if soil microorganisms modulate the potential allelopathic effects of these VOC. Thirty terpenes were detected from both, needle and root emissions with β‐caryophyllene as the major volatile. Numerous terpenes, such as β‐caryophyllene, δ‐terpinene, or α‐pinene, showed higher headspace concentrations according to the gradient green needles < senescent needles < needle litter. Seed germination and root growth of the two target species were mainly reduced in presence of P. halepensis VOC. In strong contrast with the trend reported with needle leachates in literature, we observed an increasing inhibitory effect of P. halepensis VOC with the progress of needle physiological stages (i.e., green needle < senescent needle < needle litter). Surprisingly, several inhibitory effects observed on filter paper were also found or even amplified when natural soil was used as a substrate, highlighting that soil microorganisms do not necessarily limit the negative effects of VOC released by P. halepensis on herbaceous target species.
The influence of fire frequency on the structure and botanical composition of savanna ecosystems
Authors: Ribeiro Natasha , Ruecker Gernot , Govender Navashni , Macandza Valério , Pais Aurélio , Machava Domingos , Chauque Aniceto , Lisboa Sa Nogueira , Bandeira Romana 
Published: July 2019

AbstractSavannas cover 60% of the land surface in Southern Africa, with fires and herbivory playing a key role in their ecology. The Limpopo National Park (LNP) is a 10,000 km2 conservation area in southern Mozambique and key to protecting savannas in the region. Fire is an important factor in LNP's landscapes, but little is known about its role in the park's ecology. In this study, we explored the interaction between fire frequency (FF), landscape type, and vegetation. To assess the FF, we analyzed ten years of the Moderate resolution Imaging Spectroradiometer (MODIS) burned area product (2003–2013). A stratified random sampling approach was used to assess biodiversity across three dominant landscapes (Nwambia Sandveld‐NS, Lebombo North‐LN, and Shrubveld Mopane on Calcrete‐C) and two FF levels (low—twice or less; and high—3 times or more, during 10 years). Six ha were sampled in each stratum, except for the LN versus high FF in which low accessibility allowed only 3 ha sampling. FF was higher in NS and LN landscapes, where 25% and 34% of the area, respectively, burned more than three times in 10 years. The landscape type was the main determinant of grass composition and biomass. However, in the sandy NS biomass was higher under high FF. The three landscapes supported three different tree/shrub communities, but FF resulted in compositional variations in NS and LN. Fire frequency had no marked influence on woody structural parameters (height, density, and phytomass). We concluded that the savannas in LNP are mainly driven by landscape type (geology), but FF may impose specific modifications. We recommend a fire laissez‐faire management system for most of the park and a long‐term monitoring system of vegetation to address vegetation changes related to fire. Fire management should be coordinated with the neighboring Kruger National Park, given its long history of fire management. Synthesis: This study revealed that grass and tree/shrub density, biomass, and composition in LNP are determined by the landscape type, but FF determines some important modifications. We conclude that at the current levels FF is not dramatically affecting the savanna ecosystem in the LNP (Figure 1). However, an increase in FF may drive key ecosystem changes in grass biomass and tree/shrub species composition, height, phytomass, and density.
Amperometric Immunosensor for Rapid Detection of Honeybee Pathogen Melissococcus Plutonius
Authors: Mikušová Zuzana , Farka Zdeněk , Pastucha Matěj , Poláchová Veronika , Obořilová Radka , Skládal Petr 
Published: July 2019

AbstractEuropean foulbrood (EFB) is a honeybee larvae disease caused by a bacterium Melissococcus plutonius. An amperometric immunosensor based on a sandwich assay was developed for rapid point‐of‐care detection of this pathogen. An in‐house made anti‐Melissococcus antibody was immobilized to a gold surface of a screen‐printed sensor via self‐assembled monolayer of cysteamine activated with glutaraldehyde. The direct impedimetric detection of captured microbial cells was tested, however, a better performance was obtained after the formation of sandwich with the peroxidase‐labeled antibody in the amperometric mode. The label‐free assay was limited by higher non‐specific binding. The limit of detection of the immunosensor was 6.6×104 CFU mL−1 (colony‐forming units) with wide linear range between 105 CFU mL−1 and 109 CFU mL−1. The whole analysis was completed within 2 h, which is shorter compared to common laboratory diagnostic tools, such as enzyme‐linked immunosorbent assay or polymerase chain reaction. Furthermore, atomic force microscopy was used for confirmation of the bacteria presence on the electrode surface. The developed immunosensor was successfully employed in the analysis of real samples of honeybees and larvae. The achieved results demonstrate the potential of the amperometric immunosensor for practical in‐field diagnosis of EFB, which can prevent infection spreading and connected losses of honeybee colonies.
Rb–Sr geochronology and geochemistry of pyrite from the Shihu gold deposit, central North China Craton: Implication for the timing and genesis of gold mineralization
Authors: Zeng Yong‐jie , Li Lin , Li Sheng‐Rong , Santosh M. , Song Ying‐Xin , Alam Masroor 
Published: July 2019

The Shihu quartz vein‐type gold deposit in the central North China Craton occurs within Neoarchean TTG (tonalite‐trondhjemite‐granodiorite) gneisses and shows spatial relationship with quartz diorite porphyry. The occurrence of the ore body is controlled by the N‐S fracture. Primary mineral assemblage of the ore body is composed of quartz, calcite, and base‐metal sulphides, including pyrite, galena, sphalerite, chalcopyrite, and pyrrhotite. Eight pyrite samples from veins of the main mineralization stage yield an isochron age of 129 ± 3 Ma (MSWD = 1.6), coinciding with the major Early Cretaceous magmatic event, and associated lithospheric thinning recognized in the NCC. The (87Sr/86Sr)i values of the pyrite (0.7102 ± 0.0006) are lower than the continental crust mean value (0.719) and higher than that of the mantle initial ratio (0.707), suggesting mixed crust–mantle source for the metallogenic components. Three types of hydrothermal pyrite from the early to major ore‐forming stages were identified in the quartz vein, including Py(I) as disseminated euhedral grains, Py (II) as dense bulks, and Py (III) as intergrowth with base‐metal sulphides. Electron microprobe analysis of the pyrite grains indicates a trend from S‐deficient to S‐enriched and from Fe‐enriched to Fe‐deficient stages, suggesting an increase in sulphur fugacity and reducing conditions. The arsenic in pyrite shows decrease against increasing Au during Stages II and III, implying that As is not the only trigger of gold precipitation, but electrochemical‐geochemical barrier played a major role in the formation of the ore. The Co and Ni concentrations, as well as Co/Ni ratios in pyrite, are relatively high, which provide an additional clue to the link with the regional magmatic event. Combined with the textural features, we propose a wider potential for gold exploration in this region, linking the mineralization with a major transitional tectonic regime.
Raman spectroscopy of dorsal root ganglia from streptozotocin‐induced diabetic neuropathic rats submitted to photobiomodulation therapy
Authors: Vieira Willians F. , de Magalhães Silviane F. , Farias Felipe H. , de Thomaz André A. , Parada Carlos A. 
Published: July 2019

AbstractIn this study, we used Raman spectroscopy as a new tool to investigate pathological conditions at the level of chemical bond alterations in biological tissues. Currently, there have been no reports on the spectroscopic alterations caused by diabetic neuropathy in the dorsal root ganglia (DRG). DRG are a target for the treatment of neuropathic pain, and the need for more effective therapies is increasing. Photobiomodulation therapy (PBMT) through infrared low‐level laser irradiation (904 nm) has shown analgesic effects on the treatment of neuropathy. Thus, the aim of this study was to use Raman spectroscopy to characterize the spectral DRG identities of streptozotocin (STZ)‐induced diabetic neuropathic (hyperalgesic) rats and to study the influence of PBMT over such spectra. Characteristic DRG peaks were identified at 2704, 2850, 2885, 2940, 3061 and 3160 cm−1, whose assignments are CH2/CH3 symmetric/asymmetric stretches, and C─H vibrations of lipids and proteins. DRG from hyperalgesic rats showed an increased normalized intensity of 2704, 2850, 2885 and 3160 cm−1. These same peaks had their normalized intensity reduced after PBMT treatment, accompanied by an anti‐hyperalgesic effect. Raman spectroscopy was able to diagnose spectral alterations in DRG of hyperalgesic rats and the PBMT reduced the intensity of hyperalgesia and the altered Raman spectra.
Transcription factor Tbx5 promotes cardiomyogenic differentiation of cardiac fibroblasts treated with 5‐azacytidine
Authors: Jia Yangyang , Chang Yuqiao , Guo Zhikun , Li He 
Published: July 2019

AbstractConversion of cardiac fibroblasts (CFs) into induced cardiomyocytes has recently been demonstrated, represents a potential therapeutic strategy for cardiac repair after myocardial injury. However, current approaches are inefficient. Here, we report that a defined transcription factor Tbx5, promoted cardiac reprogramming in the presence of a chemical inducer 5‐azacytidine (5‐aza). Morphological changes and cardiac specific genes and proteins expression were determined by immunofluorescence, quantitative real‐time polymerase chain reaction, and Western blot analysis. Remarkably, Tbx5 enabled cardiac reprogramming with 5‐aza by activating the expression of myocardial transcription‐related genes, including cTnT, α‐actin, Mef2c and inhibiting the expression of pluripotent genes such as Nanog, Oct4, and Sox2. Moreover, overexpression of Tbx5 upregulated the expression of sarcomere protein cTnT in CFs more efficiently at week 3 compared with 5aza‐treated alone (P < 0.05). Conversely, inhibition of Tbx5 attenuated cardiac reprogramming. Furthermore, downregulated Tbx5 decreased wnt3a expression. At the same time, the inhibition effect of Tbx5i on cardiac reprogramming was reversed in vitro when these cells were exposed to Chir99021, a GSK‐3 inhibitor. This finding provides new insight into the mechanism of cardiac reprogramming underlying the cardiac reprogramming process and lays the foundation for future clinical applications.