bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventilation of the Subtropical North Atlantic: Locations and Times of Last Ventilation Estimated Using Tracer Constraints From GEOTRACES Section GA03
Authors: Holzer Mark , Smethie William M. , Ting Yu‐Heng 
Published: March 2018

AbstractThe ventilation of the subtropical North Atlantic along GEOTRACES section GA03 is quantified in terms of where and how long ago water was last in the mixed layer. Measurements of T, S,
, CFC‐11, CFC‐12, SF6, and estimates of prebomb 14C are deconvolved for the boundary propagator
using a maximum‐entropy approach. From
, we calculate the fractions of water last ventilated in specified surface regions Ωw. We estimate that (56 ± 13)% of the water deeper than 1,000 m was ventilated in northern high latitudes, (15 ± 5)% in the Mediterranean, and (27 ± 12)% in the Southern Ocean. Below the thermocline and outside the deep western boundary current, mean ages of Ωw‐ventilated water exceed a century. Consequently, memory of where last ventilation occurred tends to get lost and the deep mean‐age patterns of Ωw‐ventilated water are broadly similar for all Ωw. The mean ventilation ages, averaged over the section with Ωw‐fraction weights, are roughly 200 years for all deep water masses except for water last ventilated south of the Antarctic divergence, which is about twice as old. The uncertainties in the section‐mean profiles of the Ωw fractions and their mean ages are ∼50% and ∼20%, respectively. The Ωw fractions have vertically diffuse overlapping patterns suggesting significant diapycnal mixing, consistent with century‐scale mean ages. We quantify the seasonal cycle of ventilation and find that in both hemispheres peak ventilation occurs during late winter and early spring, but Northern Hemisphere ventilated deep waters have a more pronounced seasonal cycle with nearly zero summertime ventilation.
An Accurate Fire‐Spread Algorithm in the Weather Research and Forecasting Model Using the Level‐Set Method
Authors: Muñoz‐Esparza Domingo , Kosović Branko , Jiménez Pedro A. , Coen Janice L. 
Published: March 2018

AbstractThe level‐set method is typically used to track and propagate the fire perimeter in wildland fire models. Herein, a high‐order level‐set method using fifth‐order WENO scheme for the discretization of spatial derivatives and third‐order explicit Runge‐Kutta temporal integration is implemented within the Weather Research and Forecasting model wildland fire physics package, WRF‐Fire. The algorithm includes solution of an additional partial differential equation for level‐set reinitialization. The accuracy of the fire‐front shape and rate of spread in uncoupled simulations is systematically analyzed. It is demonstrated that the common implementation used by level‐set‐based wildfire models yields to rate‐of‐spread errors in the range 10–35% for typical grid sizes (Δ = 12.5–100 m) and considerably underestimates fire area. Moreover, the amplitude of fire‐front gradients in the presence of explicitly resolved turbulence features is systematically underestimated. In contrast, the new WRF‐Fire algorithm results in rate‐of‐spread errors that are lower than 1% and that become nearly grid independent. Also, the underestimation of fire area at the sharp transition between the fire front and the lateral flanks is found to be reduced by a factor of ≈7. A hybrid‐order level‐set method with locally reduced artificial viscosity is proposed, which substantially alleviates the computational cost associated with high‐order discretizations while preserving accuracy. Simulations of the Last Chance wildfire demonstrate additional benefits of high‐order accurate level‐set algorithms when dealing with complex fuel heterogeneities, enabling propagation across narrow fuel gaps and more accurate fire backing over the lee side of no fuel clusters.
Nonrotating Convective Self‐Aggregation in a Limited Area AGCM
Authors: Arnold Nathan P. , Putman William M. 
Published: March 2018

AbstractWe present nonrotating simulations with the Goddard Earth Observing System (GEOS) atmospheric general circulation model (AGCM) in a square limited area domain over uniform sea surface temperature. As in previous studies, convection spontaneously aggregates into humid clusters, driven by a combination of radiative and moisture‐convective feedbacks. The aggregation is qualitatively independent of resolution, with horizontal grid spacing from 3 to 110 km, with both explicit and parameterized deep convection. A budget for the spatial variance of column moist static energy suggests that longwave radiative and surface flux feedbacks help establish aggregation, while the shortwave feedback contributes to its maintenance. Mechanism‐denial experiments confirm that aggregation does not occur without interactive longwave radiation. Ice cloud radiative effects help support the humid convecting regions but are not essential for aggregation, while liquid clouds have a negligible effect. Removing the dependence of parameterized convection on tropospheric humidity reduces the intensity of aggregation but does not prevent the formation of dry regions. In domain sizes less than (5,000 km)2, the aggregation forms a single cluster, while larger domains develop multiple clusters. Larger domains initialized with a single large cluster are unable to maintain them, suggesting an upper size limit. Surface wind speed increases with domain size, implying that maintenance of the boundary layer winds may limit cluster size. As cluster size increases, large boundary layer temperature anomalies develop to maintain the surface pressure gradient, leading to an increase in the depth of parameterized convective heating and an increase in gross moist stability.
Microfluidic Devices for Studying the Effect of Netrin‐1 on Neutrophil and Breast Cancer Cell Migration
Authors: Hipolito Jolly , Peretz‐Soroka Hagit , Torres Aniel Moya , Booy Evan , Yang Ke , Gupta Monika , Meier Markus , McKenna Sean , Koch Manuel , Santos Susy , Stetefeld Jörg , Lin Francis 
Published: March 2018

AbstractNetrin‐1 is well‐known for its chemoattractive and chemorepulsive properties for axon guidance. Early studies report that netrin‐1 inhibits granulocyte migration. On the other hand, netrin‐1 can promote cancer cell migration and invasion. The underlying mechanisms are not well understood, which requires more in‐depth characterizations of netrin‐1 mediated immune and cancer cell migration. The present study, for the first time, employs microfluidic devices that are recently developed to quantitatively investigate the effects of netrin‐1 on the motility and chemotaxis of human blood neutrophils and human breast cancer cells under well‐controlled gradient conditions. The results show that netrin‐1 reduces chemokinetic motility of human neutrophils, which is accompanied with reduced cell polarization and spreading. In addition, netrin‐1 reduces neutrophil chemotaxis to N‐formyl‐Met‐Leu‐Phe on fibronectin substrate but interestingly not on collagen substrate. By contrast, netrin‐1 promotes the migration of human breast cancer cells. Furthermore, it is found that netrin‐1 reduces neutrophil chemotaxis to the supernatant of human breast cancer cell culture. Collectively, this microfluidic cell migration study provides quantitative characterizations of the effects of netrin‐1 on the motility and chemotaxis of neutrophils and breast cancer cells, and further suggests the potential role of netrin‐1 in regulating neutrophil recruitment to breast cancer microenvironments.
Carbon‐Dot‐Decorated TiO2 Nanotubes toward Photodynamic Therapy Based on Water‐Splitting Mechanism
Authors: Yang Dan , Yang Guixin , Sun Qianqian , Gai Shili , He Fei , Dai Yunlu , Zhong Chongna , Yang Piaoping 
Published: March 2018

AbstractThe use of visible light to produce reactive oxygen species (ROS) from renewable water splitting is a highly promising means in photodynamic therapy (PDT). Up to date, diverse inorganic–organic hybrid materials developed as photosensitizers still undergo low therapeutic efficiency and/or poor stability. Herein, a kind of carbon‐nanodot‐decorated TiO2 nanotubes (CDots/TiO2 NTs) composite is developed and applied for photodynamic therapy. Upon 650 nm laser light excitation, the emissions with short wavelengths (325–425 nm) from the CDots as a result of upconversion process excite TiO2 NTs to form electron/hole (e−/h+) pairs, triggering the reaction with the adsorbed oxidants to produce ROS. Moreover, the CDots deposited on the surface of TiO2 NTs markedly enhance the light absorption response and narrow the band gap compared with anatase TiO2 nanoparticles, thereby increasing the photosensitizing efficiency. Besides, the CDots show high chemical catalytic activity for H2O2 decomposition even if no light is needed, which is essential for PDT. The excellent therapeutic performance actuated by 650 nm light is demonstrated by in vitro and in vivo assays. This photosensitizer comprises low‐cost, earth‐abundant, environment‐friendly merits, and especially excellent stability, implying its feasible application in biomedical field.
Stability of High‐Performance Pt‐Based Catalysts for Oxygen Reduction Reactions
Authors: Lin Rui , Cai Xin , Zeng Hao , Yu Zhuoping 
Published: March 2018

AbstractDue to their environmental sustainability and high efficiency, proton‐exchange‐membrane fuel cells (PEMFCs) are expected to be an essential type of energy source for electric vehicles, energy generation, and the space industry in the coming decades. Here, the recent developments regarding shape‐controlled nanostructure catalysts are reviewed, with a focus on the stability of high‐performance Pt‐based catalysts and related mechanisms. The catalysts, which possess great activity, are still far from meeting the requirements of their applications, due to stability issues, especially in membrane electrode assemblies (MEAs). Thus, solutions toward the comprehensive performance of Pt‐based catalysts are discussed here. The research trends and related theories that can promote the application of Pt‐based catalysts are also provided.
Dithieno[3,2‐b:2′,3′‐d]pyrrol Fused Nonfullerene Acceptors Enabling Over 13% Efficiency for Organic Solar Cells
Authors: Sun Jia , Ma Xiaoling , Zhang Zhuohan , Yu Jiangsheng , Zhou Jie , Yin Xinxing , Yang Linqiang , Geng Renyong , Zhu Rihong , Zhang Fujun , Tang Weihua 
Published: March 2018

AbstractA new electron‐rich central building block, 5,5,12,12‐tetrakis(4‐hexylphenyl)‐indacenobis‐(dithieno[3,2‐b:2′,3′‐d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC‐4F) are designed and synthesized. The two molecules reveal broad (600–900 nm) and strong absorption due to the satisfactory electron‐donating ability of INP. Compared with its counterpart INPIC, fluorinated nonfullerene acceptor INPIC‐4F exhibits a stronger near‐infrared absorption with a narrower optical bandgap of 1.39 eV, an improved crystallinity with higher electron mobility, and down‐shifted highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Organic solar cells (OSCs) based on INPIC‐4F exhibit a high power conversion efficiency (PCE) of 13.13% and a relatively low energy loss of 0.54 eV, which is among the highest efficiencies reported for binary OSCs in the literature. The results demonstrate the great potential of the new INP as an electron‐donating building block for constructing high‐performance nonfullerene acceptors for OSCs.
Surface Chemistry of All Inorganic Halide Perovskite Nanocrystals: Passivation Mechanism and Stability
Authors: Yang Dandan , Li Xiaoming , Zeng Haibo 
Published: March 2018

AbstractAll inorganic halide perovskite (IHP) nanocrystals (NCs) have emerged as a new class of optoelectronic materials for various applications. Surface ligands as surface passivators are essential components of nucleation and growth processes, photoluminescence quantum yields (PL QY), stability, and photoelectric applications. In this review, the relationship of perovskite structure modified is outlined by surface ligand and some properties on account of the ion structure features. This review specifically focuses on the roles of surface ligands in the construction of IHP NCs with fewer defects, higher PL QY, and better stability. Generally, ligands binding to the surface of IHP NCs can form passivation layer, which are beneficial to not only the improvement of PL QY by filling the Br− or Pb2+ vacancy but also the enhancement of stability. The surface passivation mechanisms are attributed to the [Br⋯HN+] hydrogen‐bonding, chelation, and dative covalent bond interactions. Furthermore, degradation mechanisms assigned to the hydration, ion migration, and dissociation are discussed. The equilibrium problem of purifying and QY and possible reasons are also addressed, which are believed to be solved in the near future with the help of coordination chemistry and surface engineering. Finally, a brief outlook including challenges and possible development is provided.
Fiber‐Shaped ZnO/Graphene Schottky Photodetector with Strain Effect
Authors: Zhu Zhengfeng , Wang Shalong , Zhu Ying , Liu Xuhai , Zou Yousheng , Gu Yu , Ju Dan , Zeng Haibo 
Published: March 2018

AbstractThe flexible fiber‐shaped photodetectors (PDs) suitable for wearable applications have recently attracted enormous research attention. However, the fiber‐shaped structures with the PN junction usually suffer from the poor interface between the all‐inorganic semiconductors and twisted linear electrodes. In this work, fiber‐shaped ZnO/graphene PDs based on a Schottky junction are constructed for the first time. The PDs exhibit excellent device performance because of the combination of the interface and strain engineering. In this novel structure, ZnO nanorod arrays are uniformly grown onto the Zn wire, and a graphene film is wrapped outside as the surface electrode. The built‐in electric field and the conformal contacts facilitate the separation and transport of photoinduced charge carriers. The photoresponsivity is as high as 1.92 A W−1. Moreover, the device performance can be further improved by applying external compressive strain due to the piezoelectric effect of ZnO. For instance, the responsivity of the PD under −0.33% compressive strain can increase by 12.5% and reach 2.16 A W−1.
C70 Fullerene‐Catalyzed Metal‐Free Photocatalytic ipso‐Hydroxylation of Aryl Boronic Acids: Synthesis of Phenols
Authors: Kumar Inder , Sharma Ritika , Kumar Rakesh , Kumar Rakesh , Sharma Upendra 
Published: March 2018

AbstractA metal‐free C70 fullerene‐catalyzed method has been developed for the ipso‐hydroxylation of aryl and heteroaryl boronic acids to corresponding phenols under photocatalytic conditions. The reaction proceeds under oxygen atmosphere and the mechanistic study revealed that C70 plays a critical role in the generation of reactive oxygen species in the presence of blue light. Reactions in the presence of 18O‐labelled water and oxygen confirmed the generation of reactive oxygen species from oxygen molecule. Amine used as a reductant could be recovered in the form of imine. The current method is also applicable to the synthesis of aryl ethers in one‐pot two‐step process.magnified image
Xanthan Gum–Chitosan: Delayed, prolonged, and burst‐release tablets using same components in different ratio
Authors: Consumi Marco , Leone Gemma , Pepi Simone , Tamasi Gabriella , Lamponi Stefania , Donati Alessandro , Bonechi Claudia , Rossi Claudio , Magnani Agnese 
Published: March 2018

AbstractChitosan and xanthan gum were combined in nine different percentages without using any cross‐linking agent. The obtained physical matrices were able to give a burst, delayed, or prolonged release of red yeast rice (RYR) on the basis of xanthan gum percentage. In fact, thermal analysis, swelling behavior, and rheological analysis pointed out that a slight interaction among xanthan gum and RYR was present. This was reflected in a burst release when the amount of xanthan gum was under the 30%. On the contrary, a prolonged release was observed when the xanthan gum percent was higher than 70%. A delayed release was observed using similar percentage of the polymers (i.e., F5–F7). The effect of the formulation on RYR inhibition activity toward 3‐hydroxy‐3‐methyl‐glutaryl‐coenzyme A reductase and on cholesterol production was also evaluated.
Green‐Light‐Activated Photoreaction via Genetic Hybridization of Far‐Red Fluorescent Protein and Silk
Authors: Leem Jung Woo , Park Jongwoo , Kim Seong‐Wan , Kim Seong‐Ryul , Choi Seung Ho , Choi Kwang‐Ho , Kim Young L. 
Published: March 2018

AbstractFluorescent proteins often result in phototoxicity and cytotoxicity, in particular because some red fluorescent proteins produce and release reactive oxygen species (ROS). The photogeneration of ROS is considered as a detrimental side effect in cellular imaging or is proactively utilized for ablating cancerous tissue. As ancient textiles or biomaterials, silk produced by silkworms can directly be used as fabrics or be processed into materials and structures to host other functional nanomaterials. It is reported that transgenic fusion of far‐red fluorescent protein (mKate2) with silk provides a photosensitizer hybridization platform for photoinducible control of ROS. Taking advantage of green (visible) light activation, native and regenerated mKate2 silk can produce and release superoxide and singlet oxygen, in a comparable manner of visible light‐driven plasmonic photocatalysis. Thus, the genetic expression of mKate2 in silk offers immediately exploitable and scalable photocatalyst‐like biomaterials. It is further envisioned that mKate2 silk can potentially rule out hazardous concerns associated with foreign semiconductor photocatalytic nanomaterials.
How Low Nucleation Density of Graphene on CuNi Alloy is Achieved
Authors: Liu Yifan , Wu Tianru , Yin Yuling , Zhang Xuefu , Yu Qingkai , Searles Debra J. , Ding Feng , Yuan Qinghong , Xie Xiaoming 
Published: March 2018

AbstractCuNi alloy foils are demonstrated to be one of the best substrates for synthesizing large area single‐crystalline graphene because a very fast growth rate and low nucleation density can be simultaneously achieved. The fast growth rate is understood to be due the abundance of carbon precursor supply, as a result of the high catalytic activity of Ni atoms. However, a theoretical understanding of the low nucleation density remains controversial because it is known that a high carbon precursor concentration on the surface normally leads to a high nucleation density. Here, the graphene nucleation on the CuNi alloy surfaces is systematically explored and it is revealed that: i) carbon atom dissolution into the CuNi alloy passivates the alloy surface, thereby drastically increasing the graphene nucleation barrier; ii) carbon atom diffusion on the CuNi alloy surface is greatly suppressed by the inhomogeneous atomic structure of the surface; and iii) a prominent increase in the rate of carbon diffusion into the bulk occurs when the Ni composition is higher than the percolation threshold. This study reveals the key mechanism for graphene nucleation on CuNi alloy surfaces and provides a guideline for the catalyst design for the synthesis of graphene and other 2D materials.
Microstructured Elastomer‐PEG Hydrogels via Kinetic Capture of Aqueous Liquid–Liquid Phase Separation
Authors: Lau Hang Kuen , Paul Alexandra , Sidhu Ishnoor , Li Linqing , Sabanayagam Chandran R. , Parekh Sapun H. , Kiick Kristi L. 
Published: March 2018

AbstractHeterogeneous hydrogels with desired matrix complexity are studied for a variety of biomimetic materials. Despite the range of such microstructured materials described, few methods permit independent control over microstructure and microscale mechanics by precisely controlled, single‐step processing methods. Here, a phototriggered crosslinking methodology that traps microstructures in liquid–liquid phase‐separated solutions of a highly elastomeric resilin‐like polypeptide (RLP) and poly(ethylene glycol) (PEG) is reported. RLP‐rich domains of various diameters can be trapped in a PEG continuous phase, with the kinetics of domain maturation dependent on the degree of acrylation. The chemical composition of both hydrogel phases over time is assessed via in situ hyperspectral coherent Raman microscopy, with equilibrium concentrations consistent with the compositions derived from NMR‐measured coexistence curves. Atomic force microscopy reveals that the local mechanical properties of the two phases evolve over time, even as the bulk modulus of the material remains constant, showing that the strategy permits control of mechanical properties on micrometer length scales, of relevance in generating mechanically robust materials for a range of applications. As one example, the successful encapsulation, localization, and survival of primary cells are demonstrated and suggest the potential application of phase‐separated RLP‐PEG hydrogels in regenerative medicine applications.
Improving Miscibility of a Naphthalene Diimide‐Bithiophene Copolymer with n‐Type Dopants through the Incorporation of “Kinked” Monomers
Authors: Shin Younghun , Massetti Matteo , Komber Hartmut , Biskup Till , Nava Diego , Lanzani Guglielmo , Caironi Mario , Sommer Michael 
Published: March 2018

AbstractN‐type doping of polymer semiconductors is necessary to enable printable and efficient organic thermoelectric generators. A recently reported method relies on blending air‐stable benzimidazole derivative dopant molecules with good electron transporting materials, such as the well‐known poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)}, also known as PNDIT2. One of the main limitations to doping efficiency is miscibility of the dopant with the polymer. In order to overcome such limitation, controlled amounts of the covalently incorporated, meta‐substituted monomer 1,3‐bis(2‐thienyl)benzene (TPT) (“kinked monomer”) are introduced into the otherwise straight backbone of PNDIT2. Differential scanning calorimetry shows that crystallinity of P(NDI‐alt‐[T2‐co‐TPT]) first decreases with increasing TPT content up to 5 mol%, but then increases again for higher TPT contents. Miscibility of P(NDI‐alt‐[T2‐co‐TPT]) with the dopant 4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)‐N,N‐diphenylaniline increases with increasing TPT content up to 30 mol%. The electrical conductivity of doped P(NDI‐alt‐[T2‐co‐TPT]) films is reduced with respect to PNDIT2, owing to a lower charge mobility caused by TPT units which break conjugation. Nevertheless, the doping efficiency at high doping concentration is substantially improved, with an estimated ≈20‐fold increase with respect to PNDIT2, as a result of the improved miscibility of dopant and copolymer.