scholarly journals Cohesion of bird nests

2021 ◽  
Vol 249 ◽  
pp. 06014
Author(s):  
Ignacio Andrade-Silva ◽  
Théo Godefroy ◽  
Olivier Pouliquen ◽  
Joel Marthelot
Keyword(s):  
Granular Materials ◽  
Mechanical Behaviour ◽  
Spherical Particles ◽  
Striking Difference ◽  
Rigid Spheres ◽  
Microscopic Scale ◽  
X Ray ◽  
Contact Points ◽  
Capillary Bridges ◽  
Initial Assembly

One striking difference between aggregates of flexible frictional fibres and other granular materials like rigid spheres is the effective cohesion of their assembly. While glue or capillary bridges are needed to shape aggregates of spherical particles and build sandcastles, for fibres, no need for glue to build a nest. Here we study an assembly of mono disperse flexible fibres. We first use X-ray microtomography to characterise the geometry of the initial assembly, the number of contact points and mean curvatures of the fibres. Using forcedisplacement measurements, we characterise the macroscopic cohesive strength of the aggregate by varying the geometry of the fibres, the fibres mechanicals properties and the packing of the preparation. Finally, we relate the macroscopic mechanical behaviour of the assembly with the filament reorganisation at the microscopic scale.

LPG Synthesis from Syngas over Cu/ZnO-Pd-β Catalysts Prepared by Ultrasonic Spray Pyrolysis

2015 ◽  
Vol 659 ◽  
pp. 252-256
Author(s):  
Sudarat Chaiwatyothin ◽  
Wittawat Ratanathavorn ◽  
Tharapong Vitidsant ◽  
Prasert Reubroycharoen
Keyword(s):  
Spray Pyrolysis ◽  
Fixed Bed ◽  
Ultrasonic Spray Pyrolysis ◽  
Product Distribution ◽  
Fixed Bed Reactor ◽  
Spherical Particles ◽  
Gaseous State ◽  
X Ray ◽  
Ultrasonic Spray ◽  
Co Conversion

Synthesis of nanoCu/ZnO catalyst for LPG production was prepared by ultrasonic spray pyrolysis (USP). Hollow spherical particles were obtained by USP technique using an aqueous solution of Cu (NO3)3.6H2O and Zn (NO3)3.3H2O with different concentration of 0.05, 0.1 and 0.5 molar under the pyrolysis temperatures of 600, 700 and 800°C. Mists of the solution were generated from the precursor solution by ultra sonic vibrators at frequency of ~1.7 MHz. The physicochemical properties of catalysts were characterized by X-ray diffraction, temperature-programmed reduction, scanning electron microscope, nitrogen adsorption-desorption, and energy dispersive X-ray spectrometer. The results showed that increasing in precursor concentration resulted in a large particle and particles size distributed in a range of 0.63-1.21 μm. Particles prepared at pyrolysis temperature 700°C exhibited homogeneous in size and shape compared to other temperature. The catalytic activity of nanoCu/ZnO-Pd-β catalysts was performed in a fixed-bed reactor for synthesizing LPG. The reaction took place at 260°C, 3.0 MPa, and the ratio of H2/CO = 2/1. All the products from the reactor were in gaseous state, and analyzed by on-line gas chromatography. The results showed that %CO conversion was high but decreased rapidly with increasing reaction time. Cu/ZnO catalyst prepared by co-precipitation gave higher %CO conversion than that prepared by ultrasonic spray pyrolysis. Moreover, hydrocarbon product distribution for Cu/ZnO catalyst produced at concentration 0.1 M 700°C by ultrasonic spray pyrolysis gave the highest LPG selectivity.

scholarly journals Synthesis of Silica Particles Using Ultrasonic Spray Pyrolysis Method

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 463
Author(s):  
Srecko Stopic ◽  
Felix Wenz ◽  
Tatjana-Volkov Husovic ◽  
Bernd Friedrich
Keyword(s):  
Spray Pyrolysis ◽  
Sol Gel ◽  
Ultrasonic Spray Pyrolysis ◽  
Silica Particles ◽  
Cement Industry ◽  
Submicron Particles ◽  
Spherical Particles ◽  
Spray Pyrolysis Method ◽  
X Ray ◽  
Ultrasonic Spray

Silica has sparked strong interest in hydrometallurgy, catalysis, the cement industry, and paper coating. The synthesis of silica particles was performed at 900 °C using the ultrasonic spray pyrolysis (USP) method. Ideally, spherical particles are obtained in one horizontal reactor from an aerosol. The controlled synthesis of submicron particles of silica was reached by changing the concentration of precursor solution. The experimentally obtained particles were compared with theoretically calculated values of silica particles. The characterization was performed using a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction, frequently abbreviated as XRD, was used to analyze the structure of obtained materials. The obtained silica by ultrasonic spray pyrolysis had an amorphous structure. In comparison to other methods such as sol–gel, acidic treatment, thermal decomposition, stirred bead milling, and high-pressure carbonation, the advantage of the ultrasonic spray method for preparation of nanosized silica controlled morphology is the simplicity of setting up individual process segments and changing their configuration, one-step continuous synthesis, and the possibility of synthesizing nanoparticles from various precursors.

Synthesis of Amorphous Zirconium Dioxide from Zirconyl Nitrate in Presence of Oxalic Acid

2021 ◽  
Vol 316 ◽  
pp. 127-133
Author(s):  
Yuriy Velyaev ◽  
Ilona Kometiani ◽  
Olga Miroshnichenko
Keyword(s):  
Oxalic Acid ◽  
Zirconium Dioxide ◽  
Spherical Particles ◽  
Degree Of Crystallinity ◽  
Optimum Temperature ◽  
Sorbed Water ◽  
Zirconyl Nitrate ◽  
X Ray ◽  
Low Degree ◽  
Gel Drying

The article presents the results of studies on preparation of amorphous zirconium dioxide from zirconium nitrate by its hydrolysis in the presence of oxalic acid. It is determined that the balance of reagents taken for synthesis (1 ml 0,025 M ZrO(NO3)2 is 1.35 ml 4 M HOOC-COOH), and the optimum temperature of the received gel drying, which is 230 ̊С, is established, too. Morphology of the obtained ZrO2 samples was explored. It has been found that the calcining temperature is independent of the size and shape forming irregular agglomerates, consisting of smaller spherical particles, whose diameter varies between 50 and 300 nm. The X-ray analysis of the sample is represented, which showed a low degree of crystallinity of the substance. IR spectroscopy data showed the presence of zirconium dioxide-characteristic peaks on the IR spectrum. The same spectrum reflects the presence of a large amount of sorbed water in the obtained sample, as well as peaks characteristic of the gas adsorbed by the sample from the environment.

scholarly journals Macroscopic x-ray powder diffraction imaging reveals Vermeer’s discriminating use of lead white pigments in Girl with a Pearl Earring

2019 ◽  
Vol 5 (8) ◽  
pp. eaax1975 ◽  
Author(s):  
S. De Meyer ◽  
F. Vanmeert ◽  
R. Vertongen ◽  
A. Van Loon ◽  
V. Gonzalez ◽  
...  
Keyword(s):  
Optical Properties ◽  
Powder Diffraction ◽  
Lead White ◽  
White Pigment ◽  
Microscopic Scale ◽  
X Ray ◽  
Oil Paintings ◽  
Johannes Vermeer ◽  
Diffraction Imaging ◽  
The 19Th Century

Until the 19th century, lead white was the most important white pigment used in oil paintings. Lead white is typically composed of two crystalline lead carbonates: hydrocerussite [2PbCO3·Pb(OH)2] and cerussite (PbCO3). Depending on the ratio between hydrocerussite and cerussite, lead white can be classified into different subtypes, each with different optical properties. Current methods to investigate and differentiate between lead white subtypes involve invasive sampling on a microscopic scale, introducing problems of paint damage and representativeness. In this study, a 17th century painting Girl with a Pearl Earring (by Johannes Vermeer, c. 1665, collection of the Mauritshuis, NL) was analyzed with a recently developed mobile and noninvasive macroscopic x-ray powder diffraction (MA-XRPD) scanner within the project Girl in the Spotlight. Four different subtypes of lead white were identified using XRPD imaging at the macroscopic and microscopic scale, implying that Vermeer was highly discriminatory in his use of lead white.

scholarly journals The Variation Effect of Mg-doped NPs Prepared by Sol-Gel Method on its Structural Properties and Biological Activities

2021 ◽  
Vol 2114 (1) ◽  
pp. 012004
Author(s):  
Duha S. Ahmed ◽  
Noor Q. Ali ◽  
Ali A. Taha
Keyword(s):  
Biological Activities ◽  
Sol Gel ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Nio Nps ◽  
Dopant Element ◽  
Mg Doped

Abstract In this paper, we reported the synthesis of NiO NPs and Mg doped-NiO NPs using the facile sol-gel method. Besides, the influence of the variation of Mg dopant on the structural, morphological and optical properties of the prepared Mg-NiO NPs was studied. The synthesized Mg-NiO NPs nanoparticles were characterized by X-Ray Diffraction Analysis (XRD), Energy Dispersive X-ray Spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), Field-Emission Scanning Electron Microscopy (FE-SEM), and UV-Vis spectrophotometer. The X-ray diffraction confirmed the formation of the cubic structure of Mg doped-NiO NPs after doping with the magnesium. The increase in the crystal size was observed with the increase in the concentration of the Mg dopant element. The FESEM images reveal the formation of nickel oxide through the appearance of spherical clusters, while the hybrids appear as wrinkled surface covered with spherical particles of magnesium. The UV-Vis spectrum showed a shift towards shorter wavelengths with an increase in the concentration of the Mg dopant element due to the quantum confinement effect. The hemolysis activity study showed that NiO NPs had a low hemolysis percentage of 1.47% and increased with increasing concentration. While, increasing of the RBC hemolysis (5.9%) after NiO doped with Mg. The antibacterial activity was studied against S. aureus and P. aeruginosa bacteria, and indicated the highest growth inhibition zones of Mg-doped NiO NPs as compared with NiO NPs against of Staphylococcus aureus and Pseudomonas aeruginosa, respectively.

scholarly journals Ultraviolet and violet-blue emission of Zn doped MgO/mg(OH)2 particles prepared by one step spray pyrolysis method

2018 ◽  
Vol 1 (1) ◽  
pp. 57-66
Author(s):  
Fenfen Fenda Florena ◽  
◽  
Dwindra Wilham Maulana ◽  
Ferry Faizal ◽  
Bambang Mukti Wibawa ◽  
...  
Keyword(s):  
Spray Pyrolysis ◽  
Doping Concentration ◽  
Blue Emission ◽  
Spherical Shape ◽  
Spherical Particles ◽  
Spray Pyrolysis Method ◽  
Excitation Spectra ◽  
X Ray ◽  
Pyrolysis Method ◽  
One Step

Spherical particles of Zn doped MgO were prepared by one-step spray pyrolysis method. The crystalline nature and particle size of the samples were characterized by X-ray diffraction analysis (XRD). The morphology of samples was studied by scanning electron microscope (SEM) and the presence of Zn in the sample was confirmed by energy dispersive X-ray analysis (EDX). The optical properties of the samples were investigated using photoluminescence spectroscopy (PL) analysis to obtain excitation and emission spectra of the samples. Results indicated that the doped MgO particles exhibited a cubic structure without hexagonal wurtzite structure as the Zn concentrations were increased. Spherical shape and porous particles are found with increasing of doping concentration. The optical band gap of MgO altered with the addition of doping concentration. A considerable redshift of about ~0.08 – 0.13 eV in the excitation spectra of 2.22 eV emission band was revealed in Zn doped MgO samples. It was highlighted that Zn doped MgO prepared by the spray pyrolysis generated emission at UV-Vis wavelength required for many applications.

scholarly journals Thermo-mechanical behaviour of X-ray masks in micro system technology

PAMM ◽  
2009 ◽  
Vol 9 (1) ◽  
pp. 371-372
Author(s):  
Claudia Körner ◽  
Wolfgang Seemann
Keyword(s):  
Mechanical Behaviour ◽  
System Technology ◽  
X Ray ◽  
Micro System Technology
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