bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient In‐Cloud Removal of Aerosols by Deep Convection
Authors: Yu Pengfei , Froyd Karl D. , Portmann Robert W. , Toon Owen B. , Freitas Saulo R. , Bardeen Charles G. , Brock Charles , Fan Tianyi , Gao Ru‐Shan , Katich Joseph M. , Kupc Agnieszka , Liu Shang , Maloney Christopher , Murphy Daniel M. , Rosenlof Karen H. , Schill Gregory , Schwarz Joshua P. , Williamson Christina
Published: December 2018

Convective systems dominate the vertical transport of aerosols and trace gases. The most recent in situ aerosol measurements presented here show that the concentrations of primary aerosols including sea salt and black carbon drop by factors of 10 to 10,000 from the surface to the upper troposphere. In this study we show that the default convective transport scheme in the National Science Foundation/Department of Energy Community Earth System Model results in a high bias of 10–1,000 times the measured aerosol mass for black carbon and sea salt in the middle and upper troposphere. A modified transport scheme, which considers aerosol activation from entrained air above the cloud base and aerosol‐cloud interaction associated with convection, dramatically improves model agreement with in situ measurements suggesting that deep convection can efficiently remove primary aerosols. We suggest that models that fail to consider secondary activation may overestimate black carbon's radiative forcing by a factor of 2.
High‐Resolution Constraints on Pacific Upper Mantle Petrofabric Inferred From Surface‐Wave Anisotropy
Authors: Russell Joshua B. , Gaherty James B. , Lin Pei‐Ying Patty , Lizarralde Daniel , Collins John A. , Hirth Greg , Evans Rob L.
Published: December 2018

Lithospheric seismic anisotropy illuminates mid‐ocean ridge dynamics and the thermal evolution of oceanic plates. We utilize short‐period (5–7.5 s) ambient‐noise surface waves and 15‐ to 150‐s Rayleigh waves measured across the NoMelt ocean‐bottom array to invert for the complete radial and azimuthal anisotropy in the upper ∼35 km of ∼70‐Ma Pacific lithospheric mantle, and azimuthal anisotropy through the underlying asthenosphere. Strong azimuthal variations in Rayleigh‐ and Love‐wave velocity are observed, including the first clearly measured Love‐wave 2θ and 4θ variations. Inversion of averaged dispersion requires radial anisotropy in the shallow mantle (2‐3%) and the lower crust (4‐5%), with horizontal velocities (VSH) faster than vertical velocities (VSV). Azimuthal anisotropy is strong in the mantle, with 4.5–6% 2θ variation in VSV with fast propagation parallel to the fossil‐spreading direction (FSD), and 2–2.5% 4θ variation in VSH with a fast direction 45° from FSD. The relative behavior of 2θ, 4θ, and radial anisotropy in the mantle are consistent with ophiolite petrofabrics, linking outcrop and surface‐wave length scales. VSV remains fast parallel to FSD to ∼80 km depth where the direction changes, suggesting spreading‐dominated deformation at the ridge. The transition at ∼80 km perhaps marks the dehydration boundary and base of the lithosphere. Azimuthal anisotropy strength increases from the Moho to ∼30 km depth, consistent with flow models of passive upwelling at the ridge. Strong azimuthal anisotropy suggests extremely coherent olivine fabric. Weaker radial anisotropy implies slightly nonhorizontal fabric or the presence of alternative (so‐called E‐type) peridotite fabric. Presence of radial anisotropy in the crust suggests subhorizontal layering and/or shearing during crustal accretion.
Probabilistic Tsunami Hazard Assessment in South China Sea With Consideration of Uncertain Earthquake Characteristics
Authors: Sepúlveda Ignacio , Liu Philip L.‐F. , Grigoriu Mircea
Published: December 2018

In this paper, we have conducted a probabilistic tsunami hazard assessment (PTHA) for Hong Kong (China) and Kao Hsiung (Taiwan), considering earthquakes generated in the Manila subduction zone. The new PTHA methodology with the consideration of uncertainties of slip distribution and location of future earthquakes extends the stochastic approach of Sepúlveda et al. (2017). Using sensitivity analyses, we further investigate the uncertainties of probability properties defining the slip distribution, the location, and the occurrence of earthquakes. We demonstrate that Kao Hsiung and Hong Kong would be significantly impacted by tsunamis generated by MW > 8.5 earthquakes in the Manila subduction zone. For instance, a specific MW 9.0 earthquake scenario is capable of producing tsunami amplitudes exceeding 4.0 and 3.5 m in Kao Hsiung and Hong Kong, respectively, with a probability of 50%. Despite the significant tsunami impact, great earthquakes have long mean return periods. As a result, the PTHA shows that Kao Hsiung and Hong Kong are exposed to a relatively small tsunami hazard. For instance, maximum tsunami amplitudes in the assessed locations of Kao Hsiung and Hong Kong exceed 0.32 and 0.18 m, respectively, with a mean return period of 100 years. The inundation hazard in populated areas is small as well, with mean return periods exceeding 1,000 years. Sensitivity analyses demonstrate that the PTHA can be affected by the uncertainties of the probability properties defining the slip distribution, the location, and the occurrence of earthquakes. However, PTHA results are most sensitive to the choice of the earthquake occurrence model.
Effect of Euxinic Conditions on Planktic Foraminifers: Culture Experiments and Implications for Past and Future Environments
Authors: Kuroyanagi Azumi , Toyofuku Takashi , Nagai Yukiko , Kimoto Katsunori , Nishi Hiroshi , Takashima Reishi , Kawahata Hodaka
Published: December 2018

The oceanic redox state is an essential determinant for life on Earth, and “anoxic events,” periods when large parts of the oceans were anoxic or euxinic (free hydrogen sulfide (H2S) present), may have substantially affected the oceanic biosphere. We present the first culture data showing the effects of euxinic conditions on planktic foraminifers. We cultured six species of planktic foraminifers (n = 31) in three treatments: ~2 mg H2S/L, ~9 mg H2S/L, and a control, without H2S. Under the H2S treatments, planktic foraminifers did not survive for more than 48 hr, and gametogenesis percentages were very low (8% and 17%), while the time to gametogenesis was short (less than 1 day). However, some species (e.g., Neogloboquadrina dutertrei) survived episodic or temporary exposure to H2S for a relatively short time (i.e., <24 hr, such as a tidal cycle), indicating species‐specific tolerance levels for H2S. The biological response of foraminifers to euxinia thus is fundamentally different from that of dysoxia (i.e., low dissolved oxygen; ~0.7 mg O2/L or ~22 μmol O2/L), when they survive, add chambers, feed, and undergo gametogenesis. The presence/absence of planktic foraminifers in sediments thus may help to elucidate the redox state of the euphotic zone in the oceans of the past, with planktic foraminifers absent in sediments deposited when euphotic waters became euxinic.
Waves and Sediment Transport Due to Granular Landslides Impacting Reservoirs
Authors: Li Ji , Cao Zhixian , Liu Qingquan
Published: December 2018

Granular landslides impacting reservoirs may generate large waves and cause active sediment transport, and an increased understanding of these processes is important for public safety and effective reservoir management. This study investigates the waves and sediment transport caused by landslides impacting reservoirs using a two‐dimensional coupled double‐layer‐averaged shallow water hydro‐sediment‐morphodynamic model. In contrast to existing models, which cannot fully account for sediment transport, the model makes a physical step forward. The model is benchmarked against laboratory experiments of landslide‐generated waves in both two and three dimensions. Based on extended numerical cases, the capability of the model is further demonstrated by comparisons with empirical relationships of waves in 2‐D. In addition, sediment transport is resolved in terms of the sediment concentration and bed deformation. The results show that the wave types and amplitudes in 2‐D are dictated by the sediment transport speed, which also governs the landslide‐to‐wave momentum transfer and the landslide efficiency, which is defined as the ratio of the horizontal runout distance to the vertical fall height. With increasing sediment transport speed, landslide‐generated waves in 2‐D vary gradually from smaller nonlinear oscillatory waves to larger waves with solitary‐like wave characteristics, including nonlinear transition waves, solitary waves, and dissipative transient bores. In contrast to the momentum transfer ratio, the landslide efficiency increases with the sediment transport speed and decreases with the reservoir water depth and the lateral spreading in 3‐D cases.
Tracking CO2 Plumes in Clay‐Rich Rock by Distributed Fiber Optic Strain Sensing (DFOSS): A Laboratory Demonstration
Authors: Zhang Yi , Xue Ziqiu , Park Hyuck , Shi Ji‐Quan , Kiyama Tamotsu , Lei Xinglin , Sun Yankun , Liang Yunfeng
Published: December 2018

Monitoring the migration of pore pressure, deformation, and saturation plumes with effective tools is important for the storage and utilization of fluids in underground reservoirs, such as geological stores of carbon dioxide (CO2) and natural gas. Such tools would also verify the security of the fluid contained reservoir‐caprock system. Utilizing the swelling strain attributed to pressure buildup and the adsorption of supercritical CO2 on clay minerals, we tracked the fluid plume in a natural clay‐rich Tako sandstone at the laboratory core scale. The strain was measured by a high‐resolution distributed fiber optic strain sensing (DFOSS) tool. The strain changes induced by CO2 adsorptions on clay minerals were significantly greater than those caused by pore pressure alone. The distribution of the swelling strain signals effectively captured the dynamic breakthrough of the CO2 plume from the high‐ to low‐permeability regions in the Tako sandstone. Besides revealing the in situ deformation state, the measured strain changes can track the movement of the CO2 plume as it enters the clay‐rich critical regions in the reservoir‐caprock system. The present findings and potential future applications of DFOSS in the field are expected to enhance the monitoring and management of underground fluid reservoirs.
Large Landscape Urban Irrigation: A Data‐Driven Approach to Evaluate Conservation Behavior
Authors: Quesnel Kimberly J. , Ajami Newsha K.
Published: December 2018

Nonresidential irrigation is a unique and important yet understudied urban water sector. Knowing how urban irrigators use water is critical for projecting future demands, planning diverse supply portfolios, and designing conservation strategies. In this study, we developed a holistic, analytical approach to advance knowledge about the temporal and spatial dimensions of nonresidential outdoor water use, also known as large landscape irrigation. Our approach employed data from two forthcoming technologies: dedicated irrigation meters and smart meters (i.e., advanced metering infrastructure). We then applied our methodology to a case study city in the San Francisco Bay Area, California, from 2013 to 2016 during a historic, high‐profile drought. Importantly, we uncovered behavioral differences between customers with potable versus recycled water connections and different subsectors of large landscape irrigation. Overall, conservation patterns mimicked those across California. Although they saved at lower rates, customers with recycled water followed similar conservation trends despite receiving no mandates. A weekly water use model revealed drivers of water demand, while spatial analyses showed hot and cold spots of conservation, with those in higher‐income areas conserving less as the drought progressed. A conditional inference tree partitioned diverse customers based on their conservation rates, identifying characteristics of customers who could provide the most savings in future droughts. As increasing water scarcity and population growth prompt water suppliers to optimize resources through supply diversification and demand‐side management, large landscape irrigation presents one avenue for achieving those goals.
Reactive Random Walk Particle Tracking and Its Equivalence With the Advection‐Diffusion‐Reaction Equation
Authors: Perez Lazaro J. , Hidalgo Juan J. , Dentz Marco
Published: December 2018

We present a reactive random walk particle‐tracking approach to describe bimolecular chemical reactions and show its equivalence with the advection‐diffusion‐reaction equation. The method is able to efficiently simulate reactions in d‐dimensional systems with homogeneous and spatially variable advection. Reactions among particles are determined by the reaction probability that is given in terms of the reaction rate coefficient, the total number of particles, and an interaction radius that describes the well‐mixed support volume at which all particles have the same probability to interact. The method is meshless and free of numerical dispersion. The method is validated for the bimolecular irreversible chemical reaction A + B→C in scenarios characterized by slow and fast chemical kinetics under diffusion and heterogeneous advection and diffusion.
Remote Sensing of River Bathymetry: Evaluating a Range of Sensors, Platforms, and Algorithms on the Upper Sacramento River, California, USA
Authors: Legleiter Carl J. , Harrison Lee R.
Published: December 2018

Remote sensing has become an increasingly viable tool for characterizing fluvial systems. In this study, we used field measurements with a 1.6‐km reach of the upper Sacramento River, CA, to evaluate the potential of mapping water depths with a range of platforms, sensors, and depth retrieval methods. Field measurements of water column optical properties also were compared to similar data sets from other rivers to provide context for our results. We considered field spectra, a multispectral satellite image, hyperspectral data collected from conventional and unmanned aircraft, and a bathymetric LiDAR and applied a generalized version of Optimal Band Ratio Analysis and the K nearest neighbors regression machine learning algorithm. Linear, quadratic, exponential, power, and lowess Optimal Band Ratio Analysis models enabled flexible curve‐fitting in calibrating spectrally based quantities to depth; an exponential formulation avoided artifacts associated with other model types. K nearest neighbors regression increased observed versus predicted (OP) R2 values, particularly for the satellite image; we also found that preprocessing of satellite images was unnecessary and that a basic data product could be used for depth retrieval. Bathymetric LiDAR was highly accurate and precise in shallow water, but a lack of bottom returns from areas greater than 2 m deep resulted in large gaps in coverage. The maximum detectable depth imposes an important constraint on fluvial remote sensing and a hybrid approach combined with field surveys of deep areas might be a more realistic operational strategy for bathymetric mapping. Future work will focus on scaling up from short reaches to long river segments.
Value of a Limited Number of Discharge Observations for Improving Regionalization: A Large‐Sample Study Across the United States
Authors: Pool S. , Viviroli D. , Seibert J.
Published: December 2018

Even in regions considered as densely monitored, most catchments are actually ungauged. Prediction of discharge in ungauged catchments commonly relies on parameter regionalization. While ungauged catchments lack continuous discharge time series, a limited number of observations could still be collected within short field campaigns. Here we analyze the value of such observations for improving parameter regionalization in otherwise ungauged catchments. More specifically, we propose an ensemble modeling approach, where discharge predictions from regionalization with multiple donor catchments are weighted based on the fit between predicted and observed discharge on the dates of the available observations. It was assumed that a total of 3 to 24 observations from a single hydrological year were available as an additional source of information for regionalization. This informed regionalization approach was tested with discharge observations from 10 different hydrological years in a leave‐one‐out cross validation scheme on 579 catchments in the United States using the HBV runoff model. Discharge observations helped to improve the regionalization in up to 94% of the study catchments in 8 out of 10 discharge sampling years. Sampling years characterized by exceptionally high peak discharge, or high annual or winter precipitation were less informative for regionalization. In the least informative years, model efficiency increased with an increasing number of observations. In contrast, in the most informative sampling year, 3 discharge observations provided as much information for regionalization as 24 discharge observations. Overall, discharge observations were most effective in informing regionalization in arid catchments, snow‐dominated catchments, and winter‐precipitation‐dominated catchments.
An Analysis of the Basic Processes of Formation and Change of Placebo Expectations
Authors: Geers Andrew L. , Briñol Pablo , Petty Richard E.
Published: December 2018

Placebo effects are the measurable psychological, biological, and behavioral changes that can result from expecting a treatment to be effective. Here we argue that not all expectations are created equally and there is much to learn by clarifying the psychological processes that underlie the expectations that cause placebo effects. It is proposed that the formation and change of placebo expectations can be understood from the standpoint of a general psychological model describing the basic processes of mental change. Specifically, we use the Elaboration Likelihood Model to explain how placebo-relevant variables (e.g., doctor’s lab coat, drug price, number and color of pills, patient’s mood) can work to affect expectations. Clarifying the antecedent processes responsible for placebo expectations leads to new insights regarding placebo effects, including their durability, directionality, and ability to alter subsequent behaviors (e.g., treatment adherence). A key point from our approach is that expectations causing placebo effects can be formed under high or low thought. High-thought expectations should be more likely to resist change, last over time, predict placebo effects better than low-thought expectations, and have a greater likelihood to alter subsequent behaviors. We conclude by describing a variety of theoretical innovations that this new conceptualization raises and suggest novel paths for research and application.
Analysis across multiple tumor types provides no evidence that mutant p53 exerts dominant negative activity
Authors: Shahbandi Ashkan , Jackson James G.
Published: December 2018

Missense mutations in the TP53-binding domain predominate, and >30% of these occur in just eight codons. Dominant negative properties of mutant p53, taken together with the mutation susceptibility of the nucleotides in the codon, are believed to explain the prevalence of specific mutations, including hot spots. We analyzed multiple tumor types and found no difference in clinical characteristics or survival between patients with dominant negative p53 mutant tumors and those with TP53 mutations that are predicted to be non-dominant negative. The rate tumors underwent loss of heterozygosity in these respective mutation classes was nearly identical, suggesting that presence of stable, mutant protein with predicted dominant negative activity does not reduce selective pressure to inactivate the wild-type allele. Our data suggest all inactivating mutations of TP53 are equal, and the frequency of dominant negative, hot spot mutations is likely driven more by the relative mutability of the DNA at specific codons.
Rapid and specific processing of person-related information in human anterior temporal lobe
Authors: Platonov Artem , Avanzini Pietro , Pelliccia Veronica , LoRusso Giorgio , Sartori Ivana , Orban Guy A.
Published: December 2018

The anterior temporal lobe (ATL), located at the tip of the human temporal lobes, has been heavily implicated in semantic processing by neuropsychological and functional imaging studies. These techniques have revealed a hemispheric specialization of ATL, but little about the time scale on which it operates. Here we show that ATL is specifically activated in intracerebral recordings when subjects discriminate the gender of an actor presented in a static frame followed by a video. ATL recording sites respond briefly (100 ms duration) to the visual static presentation of an actor in a task-, but not in a stimulus-duration-dependent way. Their response latencies correlate with subjects’ reaction times, as do their activity levels, but oppositely in the two hemispheres operating in a push-pull fashion. Comparison of ATL time courses with those of more posterior, less specific regions emphasizes the role of inhibitory operations sculpting the fast ATL responses underlying semantic processing.
Subpixel three-dimensional laser imaging with a downscaled avalanche photodiode array using code division multiple access
Authors: Xu Fan , Wang Yuan-Qing , Zhang Xiao-Fei , Wang Cai-Yun
Published: December 2018

Scannerless time-of-flight three-dimensional imaging, the successor to raster scanning three-dimensional imaging, relies on large-scale detector arrays to obtain high pixel resolution; however, manufacturing limitations lead to a bottleneck in imaging resolution. Here, we report a methodology for laser imaging using code division multiple access, which involves three key steps. Optical encoding is carried out for a pulsed laser to generate space-time encoded beams for projection. Optical multiplexing subdivides the backscattered light signals and multiplexes them to a downscaled avalanche-photodiode array. Subpixel decoding decodes the digitized encoded full waveforms and decomposes the features of all subpixels. Accordingly, we design a prototype based on a 64-order encoder and a 4-element avalanche-photodiode array and conduct an outdoor experiment. We demonstrate that the system is capable of obtaining 256 pixels per frame in push-broom mode and reconstruct a three-dimensional image with centimetre-level lateral resolution and range precision at a distance of ∼112 m.
A novel colorimetric and ratiometric fluorescent probe for sensing SO2 derivatives and their bio-imaging in living cells
Authors: Niu Tingting , Yu Ting , Yin Guoxing , Chen Haimin , Yin Peng , Li Haitao
Published: December 2018

We report a novel fluorescent probe HBN–TCF for the detection of SO2 derivatives.
Defective graphene@diamond hybrid nanocarbon material as an effective and stable metal-free catalyst for acetylene hydrochlorination
Authors: Lan Guojun , Qiu Yiyang , Fan Jiangtao , Wang Xiaolong , Tang Haodong , Han Wenfeng , Liu Huazhang , Liu Hongyang , Song Shuang , Li Ying
Published: December 2018

The nanodiamond–graphene hybrid material (ND@G) exhibits superior catalytic activity comparable to Au/C catalysts due to abundant surface defects.
Ratiometric temperature sensing with fluorescent thermochromic switches
Authors: Mazza Mercedes M. A. , Cardano Francesca , Cusido Janet , Baker James D. , Giordani Silvia , Raymo Françisco M.
Published: December 2018

The equilibration of two interconverting species with resolved emission translates into ratiometric fluorescence response to temperature.
First-principles theoretical designing of planar non-fullerene small molecular acceptors for organic solar cells: manipulation of noncovalent interactions
Authors: Mahmood Asif , Tang Ailing , Wang Xiaochen , Zhou Erjun
Published: December 2018

Non-fullerene small molecular acceptors (NFSMAs) exhibit promising photovoltaic performance; however, their electron mobilities are still relatively lower than those of fullerene derivatives.
Formation and infrared identification of protonated fluoranthene isomers 3-, 9-, and 10-C16H11+ in solid para-H2
Authors: Chakraborty Arghya , Lee Yuan-Pern
Published: December 2018

We produced three isomers of C16H11+ in a p-H2 matrix and compare their infrared features with extraterrestrial infrared emission (UIR) bands.
Bio-inspired chitosan-heme-vitamin B12-derived Fe–Co bimetallic-doped mesoporous carbons for efficiently electro-activating oxygen
Authors: Ma Zifan , Xu Longdi , Liu Luyao , Wang Luyao , Zhang Xiaoying , Kong Aiguo
Published: December 2018

Biomass-derived chitosan-heme-vitamin B12 with definitive molecular structures was converted to bimetallic Fe–Co-doped mesoporous carbon for efficient oxygen electroreduction.
Highly selective naked eye detection of vitamin B1 in the presence of other vitamins using graphene quantum dots capped gold nanoparticles
Authors: Sinduja B. , John S. Abraham
Published: December 2018

The application of Au-GQDs towards the sensitive determination of thiamine was demonstrated.
Silver-mediated oxidative C–C bond sulfonylation/arylation of methylenecyclopropanes with sodium sulfinates: facile access to 3-sulfonyl-1,2-dihydronaphthalenes
Authors: Liu Yu , Wang Qiao-Lin , Chen Zan , Zhou Quan , Zhou Cong-Shan , Xiong Bi-Quan , Zhang Pan-Liang , Yang Chang-An , Tang Ke-Wen
Published: December 2018

The novel AgNO3-mediated sulfonylation/arylation of a C–C σ-bond in MCPs with sodium sulfinates to synthesize 3-sulfonylated 1,2-dihydronaphthalenes is reported.
Monolithic intercalated PNIPAm/starch hydrogels with very fast and extensive one-way volume and swelling responses to temperature and pH: prospective actuators and drug release systems
Authors: Strachota Beata , Strachota Adam , Šlouf Miroslav , Brus Jiří , Cimrová Věra
Published: December 2018

Ultra-fast and extensive shrinking triggered by both pH andTwas achieved with monolithic poly(NIPAm-co-sodium methacrylate) hydrogels intercalated by starch.
PEGylated NiPAM microgels: synthesis, characterization and colloidal stability
Authors: Es Sayed Julien , Lorthioir Cédric , Perrin Patrick , Sanson Nicolas
Published: December 2018

The incorporation of hydrophilic PEG chains into the synthesis of thermoresponsive NiPAM microgels allows size-controlled and monodisperse microgels with both a constant VPTT and a high colloidal stability to be obtained.
Synergy of surface textures on a hydraulic cylinder piston
Authors: Zhang Ying , Zeng Liangcai , Wu Zhenpeng , Ding Xianzhong , Chen Kuisheng
Published: December 2018

This paper explores the synergy mechanisms that are associated with the coexistence of multiple textures, to improve the precision control of a hydraulic servo cylinder. Based on the classical Reynolds equation, it establishes a single‐texture and a nine‐texture model to compare and study the synergy of surface textures. The film thickness is obtained under different working conditions for 1 N. Based on this parameter, it compares the simulation results from the two models with the experimental results to determine if the friction coefficient is reduced when multiple textures exist. When multiple textures exist, the inlet pressures of the central texture increase, but the peak pressure and cavitation pressure decrease. The synergy of the textures acts as an ‘average pressure’ and causes the pressure to decrease, which directly decreases the shear force. As the area ratio of the texture increases, the beneficial effect from the synergy gradually increases and then decreases, which implies that there is an optimum area ratio. The depth of the texture was 10 μm and the optimum depth‐to‐diameter ratio was 0.009. When the speed increases for a light load, the oil film thickness increases. However, this phenomenon does not substantially change the synergistic effect.
A new sustainability model for measuring changes in power and access in global commodity chains: through a smallholder lens
Authors: Neimark Benjamin , Osterhoudt Sarah , Alter Hayley , Gradinar Adrian
Published: December 2018

High-value agricultural commodities face substantial economic, environmental and social sustainability challenges. As a result, commodity industries are adopting sustainable supply- and value-chain models to make production more efficient, traceable and risk-averse. These top-down models often focus on giving higher prices to smallholder producers. While an important component of sustainability, this focus on farm-gate prices has shown mixed results in part because they are less effective in highlighting the asymmetrical power relationships and the socio-economic and ecological complexity in high-value commodity production. Here, we use a novel method to measure and visualise changes in smallholder power in Madagascar’s northeast ‘vanilla triangle’—home to about 80% of the world’s high quality vanilla. Our results reveal the paradox that during the recent price surge an overall increase in smallholders’ multi-dimensional power to access economic benefits was accompanied by a decrease in many other equally important measures of sustainability. This illustrates how effective models for understanding global sustainable commodity chains should incorporate smallholders' perspectives that often emphasise complexity and uncertainty, and which aims to increase power and access for producers across both high and low price points.
An efficient approximate algorithm for nonadiabatic molecular dynamics
Authors: Hanasaki Kota , Kanno Manabu , Niehaus Thomas A. , Kono Hirohiko
Published: December 2018

We propose a modification to the nonadiabatic surface hopping calculation method formulated in a paper by Yu et al. [Phys. Chem. Chem. Phys. 16, 25883 (2014)], which is a multidimensional extension of the Zhu-Nakamura theory with a practical diabatic gradient estimation algorithm. In our modification, their diabatic gradient estimation algorithm, which is based on a simple interpolation of the adiabatic potential energy surfaces, is replaced by an algorithm using the numerical derivatives of the adiabatic gradients. We then apply the algorithm to several models of nonadiabatic dynamics, both analytic and ab initio models, to numerically demonstrate that our method indeed widens the applicability and robustness of their method. We also discuss the validity and limitations of our new nonadiabatic surface hopping method while considering in mind potential applications to excited-state dynamics of biomolecules or unconventional nonadiabatic dynamics such as radiation decay processes in ultraintense X-ray fields.
Solar mirror qualification setup, the key instrument in a new strategy for evaluating off-normal near-specular solar-reflectance
Authors: Montecchi Marco
Published: December 2018

Solar reflectance is one of the most important parameters characterizing the mirrors used to redirect the solar radiation toward a receiver in concentrating solar power plants. In Solar Power and Chemical Energy Systems (SolarPACES) Task III, an international group of experts is drafting the reflectance guidelines and debating the hard task of measuring off-normal near-specular solar-reflectance. Because of the lack of suitable commercial instruments, several research institutes are studying and setting up special equipment. Since 2012, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) proposed an articulated strategy based on modeling the hemispherical spectral reflectance with the equivalent model algorithm and the ratio of near-specular to hemispherical reflectance with the total integral scattering equation; in the latter, the roughness is replaced by the heuristic parameter σφ, nonphysically dependent on the acceptance angle. The solar mirror qualification experimental setup was conceived for measuring σφ. Recently, SolarPACES approved a new project to support the working group for improving the proposed instruments. The paper summarizes the ENEA strategy and presents the latest version of the instrument, SMQ2, discussing its several important new features: self-calibration, setup simplification, straightforward applicability to high specular mirrors, measurement-time cutoff, and acceptance-angle range extended up to 50 mrad.
In-situ near-field probe microscopy of plasma processing
Authors: Tselev Alexander , Fagan Jeffrey , Kolmakov Andrei
Published: December 2018

There exists a great necessity for in situ nanoscale characterization of surfaces and thin films during plasma treatments. To address this need, the current approaches rely on either “post mortem” sample microscopy or in situ optical methods. The latter, however, lack the required nanoscale spatial resolution. In this paper, we propose scanning near-field microwave microscopy to monitor plasma-assisted processes with a submicron spatial resolution. In our approach, a plasma environment with an object of interest is separated from the near-field probe and the rest of the microscope by a SiN membrane of a few tens of nanometer thickness, and the imaging is performed through this membrane. As a proof of concept, we were able to monitor gradual transformations of carbon nanotube films upon plasma-induced oxidation by a low-pressure air plasma. In the implemented approach with the near-field probe in contact with the membrane, the plasma processing should be interrupted during imaging to preserve the membrane integrity. Possible solutions to achieve in situ real-time imaging during plasma conditions are discussed.
Time evolution of steep diffusion fronts in highly viscous aerosol particles measured with Mie resonance spectroscopy
Authors: Bastelberger S. , Krieger U. K. , Luo B. P. , Peter Th.
Published: December 2018

Field and laboratory measurements indicate that atmospheric organic aerosol particles can be present in a highly viscous state. In contrast to liquid state particles, the gas phase equilibration to ambient relative humidity (RH) can be kinetically limited and governed by condensed phase diffusion. In water diffusion experiments on highly viscous single aerosol particles levitated in an electrodynamic balance, we observed a characteristic shift behavior of the Mie scattering resonances indicative of the changing radial structure of the particle, thus providing an experimental method to track the diffusion process inside the particle. Due to the plasticizing effect of water, theory predicts extremely steep, front-like water concentration gradients inside highly viscous particles exposed to a rapid increase in RH. The resulting quasi step-like concentration profile motivates the use of a simple core-shell model describing the morphology of the non-equilibrium particle during humidification. The particle growth and reduction of the shell refractive index can be observed experimentally as redshift and blueshift behavior of the Mie resonances, respectively. We can deduce the particle radius as well as a core-shell radius ratio from the measured shift pattern and Mie scattering calculations. Using both the growth information obtained from the Mie resonance redshift and thermodynamic equilibrium data, we can infer a comprehensive picture of the time evolution of the diffusion fronts in the framework of our core-shell model. The observed shift behavior of the Mie resonances provides direct evidence of very steep diffusion fronts caused by the plasticizing effect of water and a method to validate previous diffusivity measurements.
Information generating, sharing, and manipulating Source-Reservoir-Sink model of self-organizing dissipative structures
Authors: Ahmad Shoaib
Published: December 2018

The evolution of self-organizing ensembles of fullerenes and the emergence of the Buckyball are described by information generating, sharing, and manipulating Source-Reservoir-Sink model. Shannon's information-theoretic model of signal transmitter, channel, and receiver that preserves and retains the original signal is extended to our model that maps the transformations of chemical and physical components of the self-organizing dissipative structures into Source, Reservoir, and Sink. The information generated by Source is manipulated by controlling the flow of information to Reservoir before being transmitted to Sink. It is demonstrated in a Box-model. The role of Reservoir in building up the manipulative capacity for information storage and selective sharing is illustrated by the asymmetric exchange of material and information. The number of boxes and the flow rates are varied to evaluate the information-theoretic diagnostic tools of Shannon entropy, complexity, fractal dimension, relative entropy, and the entropic cost of the emerging dissipative structures.
Unidirectional self-transport of air bubble via a Janus membrane in aqueous environment
Authors: Yan Shuguang , Ren Feifei , Li Chuanzong , Jiao Yunlong , Wang Chaowei , Wu Sizhu , Wei Sui , Hu Yanlei , Li Jiawen , Xiao Yi , Su Yahui , Wu Dong
Published: December 2018

Inspired by natural creatures, bubble manipulation by surface microstructures in aqueous media has attracted great attention due to its promising applications in industrial production. Herein, a superhydrophobic/hydrophilic Janus aluminum membrane with tapered micropore arrays was fabricated by femtosecond laser drilling, surface fluorination, and subsequent fluorination removal. Compared with the single interception or penetration of double-faced hydrophilic or superhydrophobic membranes, the Janus membrane showed a distinctive unidirectional air bubble transport ability. In experiment, the air bubbles introduced on the lower hydrophilic surface could spontaneously move to the upper superhydrophobic surface, but they were prevented in the inverse direction. The dynamic process of unidirectional transport was in-situ monitored, and the physical mechanism was systemically investigated. In addition, the concepts of air-participating chemical/physical processes were demonstrated such as discoloration of purple litmus solution by CO2 injection, which proved the Janus membrane practicability.
Epitaxial growth of InN thin films by plasma-enhanced atomic layer deposition
Authors: Feng Xingcan , Peng Hong , Gong Jinhui , Wang Wei , Liu Hu , Quan Zhijue , Pan Shuan , Wang Li
Published: December 2018

In this study, we report on the growth of crystalline InN thin films by plasma-enhanced atomic layer deposition (PE-ALD). By systematically investigating the growth parameters, we determined the process window for crystalline InN films growth by PE-ALD. Under the optimal conditions, we compared Si (100), Al2O3 (0001), and ZnO (0001) substrates with different lattice mismatches to InN. High resolution X-ray diffraction (HR-XRD) measurements showed that we obtained the epitaxial InN thin film on the ZnO (0001) substrate, which has the smallest lattice mismatch. The crystal orientation relationship is found to be InN[0001]∥ZnO[0001] and InN[10−10]∥ZnO[10−10]. HR-XRD and high resolution transmission electron microscopy measurements revealed that the InN films are fully relaxed, and no voids or interlayer is observed at the interface. Our results show that the epitaxial growth of the InN film can be obtained by PE-ALD at low temperature.
On-the-fly ab initio semiclassical evaluation of time-resolved electronic spectra
Authors: Begušić Tomislav , Roulet Julien , Vaníček Jiří
Published: December 2018

We present a methodology for computing vibrationally and time-resolved pump-probe spectra, which takes into account all vibrational degrees of freedom and is based on the combination of the thawed Gaussian approximation with on-the-fly ab initio evaluation of the electronic structure. The method is applied to the phenyl radical and compared with two more approximate approaches based on the global harmonic approximation—the global harmonic method expands both the ground- and excited-state potential energy surfaces to the second order about the corresponding minima, while the combined global harmonic/on-the-fly method retains the on-the-fly scheme for the excited-state wavepacket propagation. We also compare the spectra by considering their means and widths, and show analytically how these measures are related to the properties of the semiclassical wavepacket. We find that the combined approach is better than the global harmonic one in describing the vibrational structure, while the global harmonic approximation estimates better the overall means and widths of the spectra due to a partial cancellation of errors. Although the full-dimensional on-the-fly ab initio result seems to reflect the dynamics of only one mode, we show, by performing exact quantum calculations, that this simple structure cannot be recovered using a one-dimensional model. Yet, the agreement between the quantum and semiclassical spectra in this simple, but anharmonic model lends additional support for the full-dimensional ab initio thawed Gaussian calculation of the phenyl radical spectra. We conclude that the thawed Gaussian approximation provides a viable alternative to the expensive or unfeasible exact quantum calculations in cases, where low-dimensional models are not sufficiently accurate to represent the full system.
Synchronization of stochastic hybrid oscillators driven by a common switching environment
Authors: Bressloff Paul C. , MacLaurin James
Published: December 2018

Many systems in biology, physics, and chemistry can be modeled through ordinary differential equations (ODEs), which are piecewise smooth, but switch between different states according to a Markov jump process. In the fast switching limit, the dynamics converges to a deterministic ODE. In this paper, we suppose that this limit ODE supports a stable limit cycle. We demonstrate that a set of such oscillators can synchronize when they are uncoupled, but they share the same switching Markov jump process. The latter is taken to represent the effect of a common randomly switching environment. We determine the leading order of the Lyapunov coefficient governing the rate of decay of the phase difference in the fast switching limit. The analysis bears some similarities to the classical analysis of synchronization of stochastic oscillators subject to common white noise. However, the discrete nature of the Markov jump process raises some difficulties: in fact, we find that the Lyapunov coefficient from the quasi-steady-state approximation differs from the Lyapunov coefficient one obtains from a second order perturbation expansion in the waiting time between jumps. Finally, we demonstrate synchronization numerically in the radial isochron clock model and show that the latter Lyapunov exponent is more accurate.
Atomic layer deposited ZnxNi1−xO: A thermally stable hole selective contact for silicon solar cells
Authors: Zhang Tian , Hossain Md. Anower , Lee Chang-Yeh , Zakaria Yahya , Abdallah Amir A. , Hoex Bram
Published: December 2018

Atomic layer deposited zinc nickel oxide (ZNO, ZnxNi1−xO) films with Zn concentrations of 0.09, 0.46, and 0.62 are investigated for application as a hole-selective contact for crystalline silicon solar cells. The ZNO films were found to be p-type by evaluating their contact performance on p-Si. A direct contact between ZNO and p-Si showed perfect ohmic behaviour. Spectroscopic ellipsometry measurements revealed a high optical transparency of the ZNO films with a bandgap of >3 eV. X-ray photoelectron spectroscopy confirmed a much lower valence band offset between ZNO and p-Si than the conduction band offset, which is favourable for selective hole extraction on p-Si. In addition, subsequent annealing at 200 °C significantly decreased the contact resistivity, and annealing temperatures up to 500 °C did not degrade its contact performance. A minimal contact resistivity of 21.5 mΩ·cm2 was obtained on p-type c-Si for a 3.4 nm ZNO film with a Zn concentration of 0.62 after annealing at 200 °C. These results demonstrate the advantages of ZnxNi1−xO as a hole-selective contact for crystalline p-Si solar cells.
Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex
Authors: Ma Tianji , Bonfanti Matteo , Eisenbrandt Pierre , Martinazzo Rocco , Burghardt Irene
Published: December 2018

Multi-configurational Ehrenfest (MCE) approaches, which are intended to remedy the lack of correlations in the standard mean-field Ehrenfest method, have been proposed as coherent-state based ansätze for quantum propagation [D. V. Shalashilin, J. Chem. Phys. 130, 244101 (2009)] and also as the classical limit of the variational Gaussian-based multiconfiguration time dependent Hartree (G-MCTDH) method [S. Römer and I. Burghardt, Mol. Phys. 111, 3618 (2013)]. In the present paper, we establish the formal connection between these schemes and assess the performance of MCE for a coherent-state representation of the classical-limit subsystem. As a representative model system, we address the ultrafast, coherent charge transfer dynamics in an oligothiophene-fullerene donor-acceptor complex described by a two-state linear vibronic coupling model. MCE calculations are compared with reference calculations performed with the MCTDH method, for 10–40 vibrational modes. Beyond a dimensionality of 10 modes, it is shown that the correct representation of electronic coherence depends crucially on the sampling of initially unoccupied Gaussians.
Digital thermal metasurface with arbitrary infrared thermogram
Authors: Shang J. , Tian B. Y. , Jiang C. R. , Huang J. P.
Published: December 2018

An object exhibits the infrared thermogram of another object, which is called thermal illusion as extensively investigated in the field of thermal metamaterials. However, almost all the existing thermal illusion behaviors were theoretically designed by using unconventional thermal conductivities, which means that the conductivities must be anisotropic, graded, or even singular due to the analytical methods in use. This problem largely limits fabrications for applications. By suggesting two discretization steps, here we put forward a numerical method instead to design thermal illusion, for which unconventional conductivities are no longer needed. In the meantime, more importantly, we reveal different thermal illusion behaviors. By tailoring the joint effects of thermal conduction and convection, we design a thermal pixel of cuboidal shape. We show that the assembly of such pixels into different two-dimensional arrays could generate infrared thermograms of different objects, which is thus called the digital thermal metasurface. Also, the metasurface is reconfigurable, and it can apparently produce all the existing thermal illusion behaviors reported in the literature. Finally, we experimentally fabricate a prototype. This work opens a door for applying conventional thermal conductivities of commercially available materials to thermal illusion, and we expect it to stimulate more exciting developments in electromagnetic disguise and confrontation.