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Pengfei Yu, Karen H Rosenlof, Shang Liu, Hagen Telg, Troy D Thornberry, Andrew W Rollins, Robert W Portmann, Zhixuan Bai, Eric A Ray, Yunjun Duan, Laura L Pan, Owen B Toon, Jianchun Bian, Ru-Shan Gao
An enhanced aerosol layer near the tropopause over Asia during the June-September period of the Asian summer monsoon (ASM) was recently identified using satellite observations. Its sources and climate impact are presently not well-characterized. To improve understanding of this phenomenon, we made in situ aerosol measurements during summer 2015 from Kunming, China, then followed with a modeling study to assess the global significance. The in situ measurements revealed a robust enhancement in aerosol concentration that extended up to 2 km above the tropopause...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
Bowen Shu, Chunsun Zhang, Da Xing
Timely and accurate molecular diagnostics at the point-of-care (POC) level is critical to global health. To this end, we propose a handheld convective-flow real-time polymerase chain reaction (PCR) system capable of direct sample-to-answer genetic analysis for the first time. Such a system mainly consists of a magnetic bead-assisted photothermolysis sample preparation, a closed-loop convective PCR reactor, and a wireless video camera-based real-time fluorescence detection. The sample preparation exploits the dual functionality of vancomycin-modified magnetic beads (VMBs) for bacteria enrichment and photothermal conversion, enabling cell pre-concentration and lysis to be finished in less than 3min...
June 8, 2017: Biosensors & Bioelectronics
Oana-Viorela Nistor, Liliana Seremet Ceclu, Doina Georgeta Andronoiu, Ludmila Rudi, Elisabeta Botez
There is an increased interest in preserving fruits and vegetables by drying. The novelty of this study consists in the combination of the following three drying methods: free convection (at 50, 60, and 70°C), forced convection at 40°C and 315W microwave power. The aim of this study was to investigate the effects of the drying conditions on red beetroot (Beta vulgaris L.) in terms of betalain variance, and polyphenol, microstructure changes (SEM). A strong thermal shock, provided by convection at 60° followed by microwave wattage 315W/9min, leads to a better preservation of bioactive compounds content (0...
December 1, 2017: Food Chemistry
Yi Yang, Stefan Bruns, Susan Louise Svane Stipp, Henning Osholm Sørensen
When reactive fluids flow through a dissolving porous medium, conductive channels form, leading to fluid breakthrough. This phenomenon is caused by the reactive infiltration instability and is important in geologic carbon storage where the dissolution of CO2 in flowing water increases fluid acidity. Using numerical simulations with high resolution digital models of North Sea chalk, we show that the breakthrough porosity is an important indicator of dissolution pattern. Dissolution patterns reflect the balance between the demand and supply of cumulative surface...
June 16, 2017: Environmental Science & Technology
Amihai Horesh, Matvey Morozov, Ofer Manor
We study the thinning and drainage of the intermediate liquid film between a bubble and a solid surface at close proximity in the presence of a surface acoustic wave (SAW) in the solid. Specifically, we employ the diffraction of light to observe a long air bubble confined in a solid rectangular channel filled with silicone oil. This setup, constituting a two-dimensional physical model of thin film drainage, allows us to analyze the influence of a SAW on the rate of thinning of the micron-thick liquid film separating the bubble and the solid substrate...
May 2017: Physical Review. E
Thomas Köllner, Thomas Boeck, Jörg Schumacher
The combined effects of buoyancy-driven Rayleigh-Bénard convection (RC) and surface tension-driven Marangoni convection (MC) are studied in a triple-layer configuration which serves as a simplified model for a liquid metal battery (LMB). The three-layer model consists of a liquid metal alloy cathode, a molten salt separation layer, and a liquid metal anode at the top. Convection is triggered by the temperature gradient between the hot electrolyte and the colder electrodes, which is a consequence of the release of resistive heat during operation...
May 2017: Physical Review. E
Valentina Valori, Gerrit Elsinga, Martin Rohde, Mark Tummers, Jerry Westerweel, Tim van der Hagen
The effects of strongly varying fluid properties, beyond the validity range of the so-called Boussinesq approximation, were experimentally studied in Rayleigh-Bénard (RB) convection. Two experiments were conducted in the same cubical RB convection cell at similar Rayleigh and Prandtl numbers. In one experiment water was used as working fluid and the imposed temperature difference between the top and bottom plates of the cell was such to ensure non-Boussinesq conditions. In the other experiment, taken as a reference for Boussinesq conditions, methanol was used as working fluid, allowing a smaller temperature difference between the plates...
May 2017: Physical Review. E
Rong Liu, Zijing Ding
The stability of the gravity-driven flow of a viscous film coating the inside of a tube with a porous wall is studied theoretically. We used Darcy's law to describe the motion of fluids in a porous medium. The Beaver-Joseph condition is used to describe the discontinuity of velocity at the porous-fluid interface. We derived an evolution equation for the film thickness using a long-wave approximation. The effect of velocity slip at the porous wall is identified by a parameter β. We examine the effect of β on the temporal stability, the absolute-convective instability (AI-CI), and the nonlinear evolution of the interface deformation...
May 2017: Physical Review. E
Y H Wu, W L Wang, N Yan, B Wei
The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary Co_{43}Cu_{40}Pb_{17} immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center...
May 2017: Physical Review. E
Guillaume Longatte, Manon Guille-Collignon, Frédéric Lemaître
In the past years, many strategies were implemented to take benefits from oxygenic photosynthesis to harvest photosynthetic electrons and produce a significant photocurrent. Therefore, electrochemical tools were considered and globally relied on the electron transfer(s) between the photosynthetic chain and a collecting electrode. In this context, we recently reported the implementation of an electrochemical set-up at the preparative scale to produce photocurrents from a Chlamydomonas reinhardtii algae suspension with an appropriate mediator (2,6-DCBQ) and a carbon gauze as the working electrode...
June 15, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Hyekyung Lee, Junsuk Kim, Hyeonsoo Kim, Ho-Young Kim, Hyomin Lee, Sung Jae Kim
Over the past decade, nanofluidic diodes that rectify ionic currents (i.e. greater current in one direction than in the opposite direction) have drawn significant attention in biomolecular sensing, switching and energy harvesting devices. To obtain current rectification, conventional nanofluidic diodes have utilized complex nanoscale asymmetry such as nanochannel geometry, surface charge density, and reservoir concentration. Avoiding the use of sophisticated nano-asymmetry, micro/nanofluidic diodes using microscale asymmetry have been recently introduced; however, their diodic performance is still impeded by (i) low (even absent) rectification effects at physiological concentrations over 100 mM and strong dependency on the bulk concentration, and (ii) the fact that they possess only passive predefined rectification factors...
June 15, 2017: Nanoscale
Zhejun Liu, Haomin Song, Dengxin Ji, Chenyu Li, Alec Cheney, Youhai Liu, Nan Zhang, Xie Zeng, Borui Chen, Jun Gao, Yuesheng Li, Xiang Liu, Diana Aga, Suhua Jiang, Zongfu Yu, Qiaoqiang Gan
Passive solar vapor generation represents a promising and environmentally benign method of water purification/desalination. However, conventional solar steam generation techniques usually rely on costly and cumbersome optical concentration systems and have relatively low efficiency due to bulk heating of the entire liquid volume. Here, an efficient strategy using extremely low-cost materials, i.e., carbon black (powder), hydrophilic porous paper, and expanded polystyrene foam is reported. Due to the excellent thermal insulation between the surface liquid and the bulk volume of the water and the suppressed radiative and convective losses from the absorber surface to the adjacent heated vapor, a record thermal efficiency of ≈88% is obtained under 1 sun without concentration, corresponding to the evaporation rate of 1...
February 27, 2017: Global Chall
Mohamed Wehbe, Malathi Anantha, Minghan Shi, Ada Wai-Yin Leung, Wieslawa H Dragowska, Léon Sanche, Marcel B Bally
Copper diethyldithiocarbamate (Cu(DDC)2) is the active anticancer agent generated when disulfiram (DSF) is provided in the presence of copper. To date, research directed toward repurposing DSF as an anticancer drug has focused on administration of DSF and copper in combination, efforts that have proven unsuccessful in clinical trials. This is likely due to the inability to form Cu(DDC)2 at relevant concentrations in regions of tumor growth. Little effort has been directed toward the development of Cu(DDC)2 because of the inherent aqueous insolubility of the complex...
2017: International Journal of Nanomedicine
Gabriel R Barrenechea, Erik Burman, Fotini Karakatsani
For the case of approximation of convection-diffusion equations using piecewise affine continuous finite elements a new edge-based nonlinear diffusion operator is proposed that makes the scheme satisfy a discrete maximum principle. The diffusion operator is shown to be Lipschitz continuous and linearity preserving. Using these properties we provide a full stability and error analysis, which, in the diffusion dominated regime, shows existence, uniqueness and optimal convergence. Then the algebraic flux correction method is recalled and we show that the present method can be interpreted as an algebraic flux correction method for a particular definition of the flux limiters...
2017: Numer Math (Heidelb)
Emilia Nowak, Zhihua Xie, Nina M Kovalchuk, Omar K Matar, Mark J H Simmons
This work focuses on the study of bulk flows accompanying the coalescence of two aqueous drops, one containing surfactant and the other surfactant-free, in silicone oils of various viscosities. It is observed that the surfactant-free drop intrudes into the surfactant-laden drop in the form of a penetrating jet whose speed increases and average radius decreases with increasing outer phase viscosity. Mixing patterns within the coalescing drops are due to the force imbalance caused by capillary pressure difference and surfactant-induced Marangoni stresses...
June 14, 2017: Soft Matter
Venktesh S Shirure, Andrew Lezia, Arnold Tao, Luis F Alonzo, Steven C George
Convective transport can significantly distort spatial concentration gradients. Interstitial flow is ubiquitous throughout living tissue, but our understanding of how interstitial flow affects concentration gradients in biological processes is limited. Interstitial flow is of particular interest for angiogenesis because pathological and physiological angiogenesis is associated with altered interstitial flow, and both interstitial flow and morphogen gradients (e.g., vascular endothelial growth factor, VEGF) can potentially stimulate and guide new blood vessel growth...
June 12, 2017: Angiogenesis
Ankur Miglani, Purushothaman Nandagopalan, Jerin John, Seung Wook Baek
Understanding the combustion behavior of gel fuel droplets is pivotal for enhancing burn rates, lowering ignition delay and improving the operational performance of next-generation propulsion systems. Vapor jetting in burning gel fuel droplets is a crucial process that enables an effective transport (convectively) of unreacted fuel from the droplet domain to the flame zone and accelerates the gas-phase mixing process. Here, first we show that the combusting ethanol gel droplets (organic gellant laden) exhibit a new oscillatory jetting mode due to aperiodic bursting of the droplet shell...
June 12, 2017: Scientific Reports
Daniel G Gregory, Qianying Guo, Li Lu, Christopher J Kiely, Mark A Snyder
Convectively assembled colloidal crystal templates, composed of size-tunable (ca. 15-50 nm) silica (SiO2) nanoparticles, enable versatile sacrificial templating of three-dimensionally ordered mesoporous (3DOm) metal oxides (MOx) at both mesoscopic and microscopic size scales. Specifically, we show for titania (TiO2) and zirconia (ZrO2) how this approach not only enables the engineering of the mesopore size, pore volume, and surface area but can also be leveraged to tune the crystallite polymorphism of the resulting 3DOm metal oxides...
June 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Cong Qi, Guiqing Wang, Yifeng Ma, Leixin Guo
The stability and natural convection heat transfer characteristics of TiO2-water nanofluid in enclosures with different rotation angles (α = -45°, α = 0°, α = 45°, and α = 90°) are experimentally investigated. The effects of different pH values and doses (m) of dispersant agent on the stability of TiO2-water nanofluid are investigated. It is found that TiO2-water nanofluid with m = 6 wt% and pH = 8 has the lowest transmittance and has the best stability. The effects of different rotation angles (α = -45°, α = 0°, α = 45°, and α = 90°), nanoparticle mass fractions (wt% = 0...
December 2017: Nanoscale Research Letters
Fengxian Fan, Eric J R Parteli, Thorsten Pöschel
When a thin tube is dipped into water, the water will ascend to a certain height, against the action of gravity. While this effect, termed capillarity, is well known, recent experiments have shown that agitated granular matter reveals a similar behavior. Namely, when a vertical tube is inserted into a container filled with granular material and is then set into vertical vibration, the particles rise up along the tube. In the present Letter, we investigate the effect of granular capillarity by means of numerical simulations and show that the effect is caused by convection of the granular material in the container...
May 26, 2017: Physical Review Letters
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