scholarly journals Hierarchical structures of cactus spines that aid in the directional movement of dew droplets

2016 ◽  
Vol 374 (2073) ◽  
pp. 20160110 ◽  
Author(s):  
F. T. Malik ◽  
R. M. Clement ◽  
D. T. Gethin ◽  
M. Kiernan ◽  
T. Goral ◽  
...  
Keyword(s):  
Small Area ◽  
Hierarchical Structures ◽  
Time Lapse ◽  
Fluorescent Nanoparticles ◽  
Vascular Bundles ◽  
Resonance Imaging ◽  
Sem Images ◽  
Structured Surfaces ◽  
The Core ◽  
Directional Movement

Three species of cactus whose spines act as dew harvesters were chosen for this study: Copiapoa cinerea var. haseltoniana , Mammillaria columbiana subsp. yucatanensis and Parodia mammulosa and compared with Ferocactus wislizenii whose spines do not perform as dew harvesters. Time-lapse snapshots of C. cinerea showed movement of dew droplets from spine tips to their base, even against gravity. Spines emanating from one of the areoles of C. cinerea were submerged in water laced with fluorescent nanoparticles and this particular areole with its spines and a small area of stem was removed and imaged. These images clearly showed that fluorescent water had moved into the stem of the plant. Lines of vascular bundles radiating inwards from the surface areoles (from where the spines emanate) to the core of the stem were detected using magnetic resonance imaging, with the exception of F. wislizenii that does not harvest dew on its spines. Spine microstructures were examined using SEM images and surface roughness measurements ( R a and R z ) taken of the spines of C. cinerea . It was found that a roughness gradient created by tapered microgrooves existed that could potentially direct surface water from a spine tip to its base. This article is part of the themed issue ‘Bioinspired hierarchically structured surfaces for green science’.

Combined time-lapse magnetic resonance imaging and modeling to investigate colloid deposition and transport in porous media

2017 ◽  
Vol 123 ◽  
pp. 12-20 ◽  
Author(s):  
Alizée P. Lehoux ◽  
Pamela Faure ◽  
François Lafolie ◽  
Stéphane Rodts ◽  
Denis Courtier-Murias ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Porous Media ◽  
Magnetic Resonance ◽  
Time Lapse ◽  
Resonance Imaging ◽  
Transport In Porous Media ◽  
Colloid Deposition

Photoluminescence of Hybrid Structure Base in ZnO@SiO2 Core-Shell Nanoparticles inside Porous Silicon

2019 ◽  
Vol 286 ◽  
pp. 40-48
Author(s):  
Xairo Leon ◽  
Edith Osorio ◽  
Rene Pérez-Cuapio ◽  
Carlos Bueno ◽  
Mauricio Pacio ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Luminescent Properties ◽  
Electrolyte Solutions ◽  
Hybrid Structure ◽  
Colloidal Synthesis ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Sem Images ◽  
Mesoporous Silicon ◽  
The Core

In this work, core-shell ZnO@SiO2nanoparticles (NPs) were infiltrated into a macro/meso-porous silicon (PS) structure, to study its luminescent properties. The core-shell ZnO@SiO2NPs were obtained by colloidal synthesis. The core-shell ZnO@SiO2NP was 5 nm in diameter. The macro/meso-PS structure was made in two steps: we obtained the macroporous silicon (macro-PS) layer fist and the mesoporous silicon (meso-PS) layer second. This process was conducted using different electrolyte solutions, and the change of electrolyte led to a decrease in the special charge region over the wall macro-PS layer; this allowed the building of the meso-PS layers on the walls and the bottom of the macro-PS layer. The SEM results show the cross-section of the macro/meso-PS structure with and without core-shell ZnO@SiO2NPs. These SEM images show that the core-shell ZnO@SiO2NPs that infiltrated into macro/meso-PS structure were more efficiently bonded over all the porous walls. The core-shell ZnO@SiO2PL interacted with the macro/meso-PS structure, modifying its PL intensity and controlling a shift toward a lower wavelength.

scholarly journals Monitoring gas hydrate formation with magnetic resonance imaging in a metallic core holder

2019 ◽  
Vol 89 ◽  
pp. 02008
Author(s):  
Mojtaba Shakerian ◽  
Armin Afrough ◽  
Sarah Vashaee ◽  
Florin Marica ◽  
Yuechao Zhao ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Residual Water ◽  
Saturated Sand ◽  
Resonance Imaging ◽  
The Core ◽  
T2 Distribution ◽  
Core Holder ◽  
Water Saturated

Methane hydrate deposits world-wide are promising sources of natural gas. Magnetic Resonance Imaging (MRI) has proven useful in previous studies of hydrate formation. In the present work, methane hydrate formation in a water saturated sand pack was investigated employing an MRI-compatible metallic core holder at low magnetic field with a suite of advanced MRI methods developed at the UNB MRI Centre. The new MRI methods are intended to permit observation and quantification of residual fluids in the pore space as hydrate forms. Hydrate formation occurred in the water-saturated sand at 1500 psi and 4 °C. The core holder has a maximum working pressure of 4000 psi between -28 and 80 °C. The heat-exchange jacket enclosing the core holder enabled very precise control of the sample temperature. A pure phase encode MRI technique, SPRITE, and a bulk T1-T2 MR method provided high quality measurements of pore fluid saturation. Rapid 1D SPRITE MRI measurements time resolved the disappearance of pore water and hence the growth of hydrate in the sand pack. 3D π-EPI images confirmed that the residual water was inhomogeneously distributed along the sand pack. Bulk T1-T2 measurements discriminated residual water from the pore gas during the hydrate formation. A recently published local T1-T2 method helped discriminate bulk gas from the residual fluids in the sample. Hydrate formation commenced within two hours of gas supply. Hydrate formed throughout the sand pack, but maximum hydrate was observed at the interface between the gas pressure head and the sand pack. This irregular pattern of hydrate formation became more uniform over 24 hours. The rate of hydrate formation was greatest in the first two hours of reaction. An SE-SPI T2 map showed the T2 distribution changed considerably in space and time as hydrate formation continued. Changes in the T2 distribution are interpreted as pore level changes in residual water content and environment.

scholarly journals Magnetic Resonance Imaging of Methane Hydrate Formation and Dissociation in Sandstone with Dual Water Saturation

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3231
Author(s):  
Stian Almenningen ◽  
Per Fotland ◽  
Geir Ersland
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Methane Hydrate ◽  
Water Saturation ◽  
High Water ◽  
Growth Patterns ◽  
Resonance Imaging ◽  
Initial Water ◽  
Hydrate Dissociation ◽  
The Core

This paper reports formation and dissociation patterns of methane hydrate in sandstone. Magnetic resonance imaging spatially resolved hydrate growth patterns and liberation of water during dissociation. A stacked core set-up using Bentheim sandstone with dual water saturation was designed to investigate the effect of initial water saturation on hydrate phase transitions. The growth of methane hydrate (P = 8.3 MPa, T = 1–3 °C) was more prominent in high water saturation regions and resulted in a heterogeneous hydrate saturation controlled by the initial water distribution. The change in transverse relaxation time constant, T2, was spatially mapped during growth and showed different response depending on the initial water saturation. T2 decreased significantly during growth in high water saturation regions and remained unchanged during growth in low water saturation regions. Pressure depletion from one end of the core induced a hydrate dissociation front starting at the depletion side and moving through the core as production continued. The final saturation of water after hydrate dissociation was more uniform than the initial water saturation, demonstrating the significant redistribution of water that will take place during methane gas production from a hydrate reservoir.

scholarly journals Visualization of the Peroxisomal Compartment in Living Mammalian Cells: Dynamic Behavior and Association with Microtubules

1997 ◽  
Vol 136 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Erik A.C. Wiemer ◽  
Thibaut Wenzel ◽  
Thomas J. Deerinck ◽  
Mark H. Ellisman ◽  
Suresh Subramani
Keyword(s):  
Mammalian Cells ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Time Lapse ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Small Subset ◽  
Subcellular Compartment ◽  
Directional Movement ◽  
Green Fluorescent

Peroxisomes in living CV1 cells were visualized by targeting the green fluorescent protein (GFP) to this subcellular compartment through the addition of a COOH-terminal peroxisomal targeting signal 1 (GFP–PTS1). The organelle dynamics were examined and analyzed using time-lapse confocal laser scanning microscopy. Two types of movement could be distinguished: a relatively slow, random, vibration-like movement displayed by the majority (∼95%) of the peroxisomes, and a saltatory, fast directional movement displayed by a small subset (∼5%) of the peroxisomes. In the latter instance, peak velocities up to 0.75 μm/s and sustained directional velocities up to 0.45 μm/s over 11.5 μm were recorded. Only the directional type of motion appeared to be energy dependent, whereas the vibrational movement continued even after the cells were depleted of energy. Treatment of cells, transiently expressing GFP–PTS1, with microtubule-destabilizing agents such as nocodazole, vinblastine, and demecolcine clearly altered peroxisome morphology and subcellular distribution and blocked the directional movement. In contrast, the microtubule-stabilizing compound paclitaxel, or the microfilament-destabilizing drugs cytochalasin B or D, did not exert these effects. High resolution confocal analysis of cells expressing GFP–PTS1 and stained with anti-tubulin antibodies revealed that many peroxisomes were associated with microtubules. The GFP–PTS1–labeled peroxisomes were found to distribute themselves in a stochastic, rather than ordered, manner to daughter cells at the time of mitosis.

scholarly journals Sodium-23 Magnetic Resonance Imaging Has Potential for Improving Penumbra Detection but Not for Estimating Stroke Onset Time

2014 ◽  
Vol 35 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Friedrich Wetterling ◽  
Lindsay Gallagher ◽  
Jim Mullin ◽  
William M Holmes ◽  
Chris McCabe ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Onset Time ◽  
Sodium Concentration ◽  
Artery Occlusion ◽  
Stroke Onset ◽  
Resonance Imaging ◽  
Sodium Mri ◽  
The Core ◽  
Tissue Sodium

Tissue sodium concentration increases in irreversibly damaged (core) tissue following ischemic stroke and can potentially help to differentiate the core from the adjacent hypoperfused but viable penumbra. To test this, multinuclear hydrogen-1/sodium-23 magnetic resonance imaging (MRI) was used to measure the changing sodium signal and hydrogen-apparent diffusion coefficient (ADC) in the ischemic core and penumbra after rat middle cerebral artery occlusion (MCAO). Penumbra and core were defined from perfusion imaging and histologically defined irreversibly damaged tissue. The sodium signal in the core increased linearly with time, whereas the ADC rapidly decreased by >30% within 20 minutes of stroke onset, with very little change thereafter (0.5–6 hours after MCAO). Previous reports suggest that the time point at which tissue sodium signal starts to rise above normal (onset of elevated tissue sodium, OETS) represents stroke onset time (SOT). However, extrapolating core data back in time resulted in a delay of 72±24 minutes in OETS compared with actual SOT. At the OETS in the core, penumbra sodium signal was significantly decreased (88±6%, P=0.0008), whereas penumbra ADC was not significantly different (92±18%, P=0.2) from contralateral tissue. In conclusion, reduced sodium-MRI signal may serve as a viability marker for penumbra detection and can complement hydrogen ADC and perfusion MRI in the time-independent assessment of tissue fate in acute stroke patients.

Preparation and Test of Hierarchical α-Ni(OH)2 Flowers and Spheres

2011 ◽  
Vol 311-313 ◽  
pp. 494-497
Author(s):  
Chang Yu Li ◽  
Li Li Liu ◽  
Shou Xin Liu
Keyword(s):  
Hierarchical Structures ◽  
Experimental Results ◽  
Reaction Conditions ◽  
Sem Images ◽  
Simple Route ◽  
Α Phase ◽  
Ft Ir

α-Ni(OH)2 with hierarchical structures were synthesized via a simple route using Ni(NO3)2•6H2O and urea as the starting materials. The experimental results from XRD and FT-IR showed that the samples prepared by this method had the typical α-phase and the size of samples can be control by adjusting the reaction conditions. SEM images showed many uniform flowerlike or spherelike architectures with diameters of 4-6μm consisted of dozens of nanosheets. The effects of nickel sources on the phase and morphology of the prepared samples were studied, the nickel sources had an effect on both the crystallinity and size of the prepared samples.

scholarly journals In-Situ Synchrotron SAXS and WAXS Investigation on the Deformation of Single and Coaxial Electrospun P(VDF-TrFE)-Based Nanofibers

2021 ◽  
Vol 22 (23) ◽  
pp. 12669
Author(s):  
Yi-Jen Huang ◽  
Yi-Fan Chen ◽  
Po-Han Hsiao ◽  
Tu-Ngoc Lam ◽  
Wen-Ching Ko ◽  
...  
Keyword(s):  
Hierarchical Structures ◽  
Electrospun Nanofibers ◽  
Mechanical Anisotropy ◽  
Core Shell ◽  
Length Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
Nanofiber Alignment

Coaxial core/shell electrospun nanofibers consisting of ferroelectric P(VDF-TrFE) and relaxor ferroelectric P(VDF-TrFE-CTFE) are tailor-made with hierarchical structures to modulate their mechanical properties with respect to their constituents. Compared with two single and the other coaxial membranes prepared in the research, the core/shell-TrFE/CTFE membrane shows a more prominent mechanical anisotropy between revolving direction (RD) and cross direction (CD) associated with improved resistance to tensile stress for the crystallite phase stability and good strength-ductility balance. This is due to the better degree of core/shell-TrFE-CTFE nanofiber alignment and the crystalline/amorphous ratio. The coupling between terpolymer P(VDF-TrFE-CTFE) and copolymer P(VDF-TrFE) is responsible for phase stabilization, comparing the core/shell-TrFE/CTFE with the pristine terpolymer. Moreover, an impressive collective deformation mechanism of a two-length scale in the core/shell composite structure is found. We apply in-situ synchrotron X-ray to resolve the two-length scale simultaneously by using the small-angle X-ray scattering to characterize the nanofibers and the wide-angle X-ray diffraction to identify the phase transformations. Our findings may serve as guidelines for the fabrication of the electrospun nanofibers used as membranes-based electroactive polymers.

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