bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effective Transmissivity of a Plane‐Walled Fracture With Circular Cylindrical Obstacles
Authors: Jasinski Lukasz , Dabrowski Marcin 
Published: January 2018

AbstractStimulated and propped fractures provide the conductive pathways in low matrix permeability rocks. We study the impact of fracture aperture and proppant size and fraction on the effective transmissivity of a stimulated fracture filled with a partial monolayer of proppant grains. The proppant grains are treated as circular cylindrical obstacles, and the fracture walls are planar. The key geometric parameters are the obstacle fraction f and the ratio between the fracture aperture and the obstacle diameter α. We use three‐dimensional Stokes flow numerical simulations to demonstrate that the fracture flow model given by the Reynolds equations may largely overestimate the flow rate. To circumvent the inability of the Reynolds model to fulfill the no‐slip boundary condition at the rims of the obstacles, we use the Brinkman flow model adapted to the case of fracture flow. The relative difference between the effective transmissivities computed with the Stokes and Brinkman models for systems with multiple obstacles is below 10% for fractions up to 0.5. We use the Brinkman model to study the effective transmissivity of a plane‐walled fracture with circular cylindrical obstacles. Systematic numerical simulations show that the normalized effective transmissivity is predominantly dependent on f and α, and the effects of obstacle ordering are minor. The presented numerical results can be used by petroleum engineers for estimating transmissivities of propped fractures under in situ conditions. The model can also be applied to microfluidic systems and for deriving first‐order estimates of the effective transmissivity of rough‐walled, natural fractures with load‐bearing contact areas.
Seismic Attenuation and Stiffness Modulus Dispersion in Porous Rocks Containing Stochastic Fracture Networks
Authors: Hunziker Jürg , Favino Marco , Caspari Eva , Quintal Beatriz , Rubino J. Germán , Krause Rolf , Holliger Klaus 
Published: January 2018

AbstractUnderstanding seismic attenuation and modulus dispersion mechanisms in fractured rocks can result in significant advances for the indirect characterization of such environments. In this paper, we study attenuation and modulus dispersion of seismic waves caused by fluid pressure diffusion (FPD) in stochastic 2‐D fracture networks, allowing for a state‐of‐the‐art representation of natural fracture networks by a power law length distribution. To this end, we apply numerical upscaling experiments consisting of compression and shear tests to our samples of fractured rocks. The resulting P and S wave attenuation and modulus dispersion behavior is analyzed with respect to the density, the length distribution, and the connectivity of the fractures. We focus our analysis on two manifestations of FPD arising in fractured rocks, namely, fracture‐to‐background FPD at lower frequencies and fracture‐to‐fracture FPD at higher frequencies. Our results indicate that FPD is sensitive not only to the fracture density but also to the geometrical characteristics of the fracture length distributions. In particular, our study suggests that information about the local connectivity of a fracture network could be retrieved from seismic data. Conversely, information about the global connectivity, which is directly linked to the effective hydraulic conductivity of the probed volume, remains rather difficult to infer.
The Variability and Interpretation of Earthquake Source Mechanisms in The Geysers Geothermal Field From a Bayesian Standpoint Based on the Choice of a Noise Model
Authors: Mustać Marija , Tkalčić Hrvoje , Burky Alexander L. 
Published: January 2018

AbstractMoment tensor (MT) inversion studies of events in The Geysers geothermal field mostly focused on microseismicity and found a large number of earthquakes with significant non‐double‐couple (non‐DC) seismic radiation. Here we concentrate on the largest events in the area in recent years using a hierarchical Bayesian MT inversion. Initially, we show that the non‐DC components of the MT can be reliably retrieved using regional waveform data from a small number of stations. Subsequently, we present results for a number of events and show that accounting for noise correlations can lead to retrieval of a lower isotropic (ISO) component and significantly different focal mechanisms. We compute the Bayesian evidence to compare solutions obtained with different assumptions of the noise covariance matrix. Although a diagonal covariance matrix produces a better waveform fit, inversions that account for noise correlations via an empirically estimated noise covariance matrix account for interdependences of data errors and are preferred from a Bayesian point of view. This implies that improper treatment of data noise in waveform inversions can result in fitting the noise and misinterpreting the non‐DC components. Finally, one of the analyzed events is characterized as predominantly DC, while the others still have significant non‐DC components, probably as a result of crack opening, which is a reasonable hypothesis for The Geysers geothermal field geological setting.
Highly Efficient Nonlinear Optical Conversion in Waveguiding GaSe Nanoribbons with Pump Pulses Down to a Femto‐Joule Level
Authors: Liao Feng , Wang Yu , Peng Tao , Peng Jian , Gu Zhaoqi , Yu Huakang , Chen Tao , Yu Jiaxin , Gu Fuxing 
Published: January 2018

AbstractLayered GaSe flakes have revealed strongest second‐harmonic (SH) generation among all the two‐dimensional (2D) atomic crystals measured up to now. However, the unique feature of physical atomic thickness at nanometer scale prevents their practical applications in efficient nonlinear optical conversion due to limited light–matter interaction length. In this work, high quality single‐crystal GaSe nanoribbons (NRs) are fabricated and demonstrated as waveguides with good performance. By taking advantage of the strong confinement and long interaction length of the waveguiding approach, significantly enhanced nonlinear light–matter interaction is observed in GaSe NRs. Based on transverse SH generation, a single GaSe NR‐configured optical auto‐correlator is constructed for ultrashort pulse characterization. Because of the large second‐order nonlinear susceptibility, high sensitivity down to few femto‐joule (fJ) is realized. To the best of our knowledge, this is the highest energy sensitivity among the reported nanoscale auto‐correlators. Such NR waveguides and devices are highly compatible with standard optical fiber systems. The presented results may enable the construction of future energy efficient nonlinear photonic circuitry, chips, and devices.
Sorption behavior of methylene blue and rhodamine B mixed dyes onto chitosan graft poly (acrylic acid‐co‐2‐acrylamide‐2‐methyl propane sulfonic acid) hydrogel
Authors: Tang Yaoji , He Tengteng , Liu Yangwenyi , Zhou Bin , Yang Rui , Zhu Linhui 
Published: January 2018

AbstractChitosan graft poly(acrylic acid‐co‐2‐acrylamide‐2‐methyl propane sulfonic acid) (CTS‐g‐P(AA‐co‐AMPS)) hydrogel is prepared and used to remove methylene blue (MB) and rhodamine B (RB) mixed dyes from aqueous solutions. The effect of adsorption conditions, including the initial concentrations of dye solutions, contact time, initial pH values, ionic strength, and the adsorbent dosage, on the adsorption capacities is investigated. The maximal adsorption capacity for MB and RB is 936.0 and 556.9 mg/g, respectively. The adsorption isotherms of the mixed dyes are discussed using the extended Langmuir (EL) and the extended Freundlich (EF) isotherm equations. It indicates that the adsorption of both dyes is in good agreement with the extended Freundlich isotherm. Meanwhile, the adsorption processes of both dyes are spontaneous. Adsorption kinetics is in accordance with the pseudo‐second‐order kinetic equation. It is concluded that the available adsorption sites are shared by both kinds of the dye molecules. The difference of the maximal adsorption capacities of the two dyes is due to their different affinity to the adsorbent.
Modularized Extracellular Vesicles: The Dawn of Prospective Personalized and Precision Medicine
Authors: Tao Shi‐Cong , Guo Shang‐Chun , Zhang Chang‐Qing 
Published: January 2018

AbstractExtracellular vesicles (EVs) are ubiquitous nanosized membrane vesicles consisting of a lipid bilayer enclosing proteins and nucleic acids, which are active in intercellular communications. EVs are increasingly seen as a vital component of many biological functions that were once considered to require the direct participation of stem cells. Consequently, transplantation of EVs is gradually becoming considered an alternative to stem cell transplantation due to their significant advantages, including their relatively low probability of neoplastic transformation and abnormal differentiation. However, as research has progressed, it is realized that EVs derived from native‐source cells may have various shortcomings, which can be corrected by modification and optimization. To date, attempts are made to modify or improve almost all the components of EVs, including the lipid bilayer, proteins, and nucleic acids, launching a new era of modularized EV therapy through the “modular design” of EV components. One high‐yield technique, generating EV mimetic nanovesicles, will help to make industrial production of modularized EVs a reality. These modularized EVs have highly customized “modular design” components related to biological function and targeted delivery and are proposed as a promising approach to achieve personalized and precision medicine.
Stretchable Polymer Semiconductors for Plastic Electronics
Authors: Wang Ging‐Ji Nathan , Gasperini Andrea , Bao Zhenan 
Published: January 2018

AbstractConjugated polymers have evolved significantly in the past decade and have proven to be more than poorly conducting plastics. Instead, improved understanding has resulted in respectable charge‐carrier mobilities and power‐conversion efficiencies achieved by various donor‐acceptor‐type semiconducting polymers. However, their advantages in mechanical flexibility and deformability seem to have conflicting molecular design requirements from those for high charge‐carrier transporting properties. It is therefore a challenge to enhance the mechanical compliance of semiconducting polymers suitable for stretchable device applications. This progress report starts with a brief introduction to fracture mechanics and mechanical characterization techniques for thin polymer films, in order to consider the limitations and rationalization of current definition and parameters for stretchability. It then surveys different strategies that can be applied to improve the mechanical robustness and stretchability of polymer semiconductors, in particular focusing on molecular design aspects such as molecular weight and regioregularity, structural modifications in the polymer backbone and side chain, and postpolymerization modifications including blending and cross‐linking. Finally, directions for future development of next‐generation stretchable conjugated polymers are indicated.
Mimic the Photosystem II for Water Oxidation in Neutral Solution: A Case of Co3O4
Authors: Ni Bing , Wang Kai , He Ting , Gong Yue , Gu Lin , Zhuang Jing , Wang Xun 
Published: January 2018

AbstractThe photosystem II (PSII) in green plants exhibits marvelous oxygen production in neutral environments. However, artificially developed oxygen evolution catalysts (OECs) show much less activity, and the oxygen evolution reaction (OER) is now becoming a bottleneck in many energy‐related issues. Here, the PSII is mimicked to design an efficient OER system in neutral environments by introducing an oleylamine (OAm) organic layer to cap the Co3O4 OEC, and employing buffers as proton shuttles in the system. Consequently, the activity is largely enhanced. The current density can reach 10 mA cm−2 at an overpotential (η) of 390 mV in the best case in neutral environment. The turnover frequency is 0.0117 at η of 400 mV, almost the same as that in 1 m KOH solutions. The surface chemistry of the Co3O4 OEC indicates that the OAm can promote the activity. The reason that buffers as proton shuttles can greatly facilitate the reaction is ascribed to the proton‐coupled electron transfer process in the OER mechanism. These results may stimulate new perspectives on mimicking natural systems as well as new insights in electrocatalysis.
Enhanced Cyclability of Lithium–Oxygen Batteries with Electrodes Protected by Surface Films Induced via In Situ Electrochemical Process
Authors: Liu Bin , Xu Wu , Tao Jinhui , Yan Pengfei , Zheng Jianming , Engelhard Mark H. , Lu Dongping , Wang Chongmin , Zhang Ji‐Guang 
Published: January 2018

AbstractAlthough the rechargeable lithium–oxygen (Li–O2) batteries have extremely high theoretical specific energy, the practical application of these batteries is still limited by the instability of their carbon‐based air‐electrode, Li metal anode, and electrodes, toward reduced oxygen species. Here a simple one‐step in situ electrochemical precharging strategy is demonstrated to generate thin protective films on both carbon nanotubes (CNTs), air‐electrodes and Li metal anodes simultaneously under an inert atmosphere. Li–O2 cells after such pretreatment demonstrate significantly extended cycle life of 110 and 180 cycles under the capacity‐limited protocol of 1000 mA h g−1 and 500 mA h g−1, respectively, which is far more than those without pretreatment. The thin‐films formed from decomposition of electrolyte during in situ electrochemical precharging processes in an inert environment, can protect both CNTs air‐electrode and Li metal anode prior to conventional Li–O2 discharge/charge cycling, where reactive reduced oxygen species are formed. This work provides a new approach for protection of carbon‐based air‐electrodes and Li metal anodes in practical Li–O2 batteries, and may also be applied to other battery systems.
Coupled Supercapacitor and Triboelectric Nanogenerator Boost Biomimetic Pressure Sensor
Authors: Zou Jingdian , Zhang Meng , Huang Jinrong , Bian Jie , Jie Yang , Willander Magnus , Cao Xia , Wang Ning , Wang Zhong Lin 
Published: January 2018

AbstractWith the fast development of supercapacitor and triboelectric nanogenerator (TENG), it is now possible to fabricate biomimetic pressure sensors with high flexibility and sustainability. Herein, an ultrathin supercapacitor is fabricated with the paper sheet and the solid electrolyte for storing energy generated by TENG. With a sandwich design, the triboelectrodes sandwiched within the two solid supercapacitors can not only store electrical energy by a wireless energy transfer mode but also help TENG imitate the receptor's unique characteristics by simultaneously measuring both static and dynamic pressures in a self‐driven mode. In addition, the voltage of the supercapacitor increases linearly with the vibration times, which hints that this integrated device also endows functions such as vibration counting and frequency computing. This work contributes to new strategies for making multifunctional biomimetic electronics that promote the development of artificial intelligence.
Synthesis and Chemical Transformations of Fluorosulfates
Authors: Revathi Lekkala , Ravindar Lekkala , Leng Jing , Rakesh Kadalipura Puttaswamy , Qin Hua‐Li 
Published: January 2018

AbstractFluorosulfates are readily available electrophiles that can be prepared from the reactions of phenol or alcohol derivatives with sulfuryl fluoride, fluorosulfonic acid, sulfuryl chloride fluoride, and fluorosulfonic anhydride. This Focus Review covers most of the synthetic strategies that have been reported for the construction of fluorosulfates, as well as their application as versatile building blocks in a variety of synthetic transformations, such as catalyzed amination, cross‐coupling, sulfur(VI) fluoride exchange, carbonylation, hydrolysis, alcoholysis, and as alternatives to organic halides or triflates in organic chemistry.
Rhodium‐Catalyzed Enantioselective Formal [4+1] Cycloaddition of Diazooxindoles and the Danishefsky Diene
Authors: Cao Fei , Hu Fang , Xie Qi‐Mei , Luo Gao‐Ya , Chu Wen‐Dao , He Long , Liu Quan‐Zhong 
Published: January 2018

AbstractOptically enriched cyclopentenones are synthetically versatile molecules, and their rapid and efficient straightforward assembly from simple starting materials is highly desired. Herein, we report a rhodium‐catalyzed enantioselective formal [4+1] cycloaddition of diazooxindoles and the Danishefsky diene. The formation of cyclopentenones proceeds via ring expansion of the vinylcyclopropanes formed in situ via cyclopropanation. The optically and highly structurally enriched indoline spirocyclopentenone bearing an all‐carbon stereocenter was formed in a one‐pot, two‐step manner in good to excellent yields and enantioselectivities (up to 90 % ee).
Electrifying Organic Synthesis
Authors: Wiebe Anton , Gieshoff Tile , Möhle Sabine , Rodrigo Eduardo , Zirbes Michael , Waldvogel Siegfried R. 
Published: January 2018

AbstractThe direct synthetic organic use of electricity is currently experiencing a renaissance. More synthetically oriented laboratories working in this area are exploiting both novel and more traditional concepts, paving the way to broader applications of this niche technology. As only electrons serve as reagents, the generation of reagent waste is efficiently avoided. Moreover, stoichiometric reagents can be regenerated and allow a transformation to be conducted in an electrocatalytic fashion. However, the application of electroorganic transformations is more than minimizing the waste footprint, it rather gives rise to inherently safe processes, reduces the number of steps of many syntheses, allows for milder reaction conditions, provides alternative means to access desired structural entities, and creates intellectual property (IP) space. When the electricity originates from renewable resources, this surplus might be directly employed as a terminal oxidizing or reducing agent, providing an ultra‐sustainable and therefore highly attractive technique. This Review surveys recent developments in electrochemical synthesis that will influence the future of this area.
Evaluation of UiO‐66 metal organic framework as an effective sorbent for Curcumin's overdose
Authors: Molavi Hossein , Zamani Mostafa , Aghajanzadeh Mozhgan , Kheiri Manjili Hamidreza , Danafar Hossein , Shojaei Akbar 
Published: January 2018

Metal organic frameworks (MOFs) UiO‐66 (UiO stands for University of Oslo) and NH2‐UiO‐66 were prepared and characterized as sorbent (antidotal agents) for curcumin (CUR) adsorption. The structure of products were characterized by X‐ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Attenuated Total Reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), and N2 adsorption–desorption measurements. FESEM showed NH2‐UiO‐66 displayed symmetrical crystals with triangular base pyramid morphology, with the particle size around 100 nm and uniform size distribution. Adsorption capacities of CUR/MOFs with different mass ratios in the feed were investigated in the present study, and this investigation revealed that when the CUR/MOFs with mass ratio was around 0.4, the absorption capacity of NH2‐UiO‐66 had tended to maximum. Although, functionalization reduced the specific surface area and free volume, introducing polar amine groups could improve the affinity of NH2‐UiO‐66 respect to CUR. Kinetic studies showed that the kinetic data are well fitted with the pseudo‐ second‐order model. MTT assay revealed that MOFs at the concentration range of 0–560 μg/ml had no cytotoxic effect on the Human Foreskin Fibroblast normal cell line (HFF‐2). These results suggest that these MOFs could be safe as sorbent for adsorb CUR from the body.
The Attraction Effect in Experience‐based Decisions
Authors: Hadar Liat , Danziger Shai , Hertwig Ralph 
Published: January 2018

AbstractPrevious demonstrations of the attraction effect were limited to explicitly described attribute values (including numerically indexed attributes, such as gambles' outcomes and their likelihoods, or perceptual attributes, such as rectangles' height and width). However, in many real‐life decisions, such as the choice of a preferred grocer, people decide based on their past experience with the options' attributes (e.g., the frequency and magnitude of product discounts over time). We examine whether the attraction effect extends from description‐based to experience‐based choice between gambles. Our results demonstrate that the attraction effect exists but is less prevalent in experience‐based than in description‐based choice. This is because the dominance relationship, necessary for the attraction effect to occur, is more difficult to recognize in experience‐based choice. Yet, when dominance is recognized, people may use it to guide difficult trade‐off choices. We discuss practical implications. Copyright © 2018 John Wiley & Sons, Ltd.
Preparation and application of sulfated xylan as a flocculant for dye solution
Authors: Liu Zhongming , Xu Dingding , Kong Fangong , Wang Shoujuan , Yang Guihua , Fatehi Pedram 
Published: January 2018

The main purpose of this study is to explore the sulfation of xylan to produce an anionic flocculant, sulfated xylan, for removing ethyl violet dye from simulated dye solutions. In this work, xylan was sulfated with chlorosulfonic acid in N, N‐dimethylformamide solvent and the reaction conditions were optimized using a response surface methodology. It was observed that the maximum degree of substitution of 1.1 was obtained for sulfated xylan under the conditions of 3.71 chlorosulfonic acid/xylan molar ratio, 70°C and 7 h reaction time. The resulting sulfated xylan had a charge density of −3.12 mmol/g and molecular weight (Mw) of 22,300 g/mol. Furthermore, elemental and thermogravimetric analyses, Fourier transform infrared spectroscopy and proton nuclear magnetic resonance (1H‐NMR) confirmed the sulfation of xylan. The application of sulfated xylan as a flocculant for decolorizing the simulated ethyl violet dye wastewater was studied. The results indicated that 97% of dye was removed from 50 mg/L dye solution at the sulfated concentration of 175 mg/L and pH 9, but unmodified xylan was ineffective in flocculating and removing dye segments. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:529–536, 2018