Increasing aspect ratio of particles suppresses buckling in shells formed by drying suspensions

Soft Matter ◽  
2020 ◽  
Vol 16 (42) ◽  
pp. 9643-9647
Author(s):  
Ahmed Al Harraq ◽  
Bhuvnesh Bharti
Keyword(s):  
Aspect Ratio ◽  
Particle Shape ◽  
Colloidal Suspensions ◽  
Shape Anisotropy

The article identifies the role of particle shape anisotropy in suppressing the buckling of drying droplets of colloidal suspensions.

scholarly journals Role of particle shape anisotropy on crack formation in drying of colloidal suspension

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Venkateshwar Rao Dugyala ◽  
Hisay Lama ◽  
Dillip K. Satapathy ◽  
Madivala G. Basavaraj
Keyword(s):  
Particle Shape ◽  
Crack Formation ◽  
Colloidal Suspension ◽  
Shape Anisotropy

Investigation into the role of poly(vinylpyrrolidone) in the growth of high aspect ratio silver nanowires

2021 ◽  
Vol 128 ◽  
pp. 108558
Author(s):  
Yuyue Guo ◽  
Yangfei Hu ◽  
Xiaojiong Luo ◽  
Shudong Lin ◽  
Jiwen Hu ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Silver Nanowires

scholarly journals Atmospheric Ice Particle Shape Estimates from Polarimetric Radar Measurements and In Situ Observations

2017 ◽  
Vol 34 (12) ◽  
pp. 2569-2587 ◽  
Author(s):  
Sergey Y. Matrosov ◽  
Carl G. Schmitt ◽  
Maximilian Maahn ◽  
Gijs de Boer
Keyword(s):  
Aspect Ratio ◽  
Particle Shape ◽  
Characteristic Size ◽  
In Situ Measurements ◽  
Department Of Energy ◽  
Depolarization Ratio ◽  
Suggested Approach ◽  
Aspect Ratios ◽  
Radar Measurements

AbstractA remote sensing approach to retrieve the degree of nonsphericity of ice hydrometeors using scanning polarimetric Ka-band radar measurements from a U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program cloud radar operated in an alternate transmission–simultaneous reception mode is introduced. Nonsphericity is characterized by aspect ratios representing the ratios of particle minor-to-major dimensions. The approach is based on the use of a circular depolarization ratio (CDR) proxy reconstructed from differential reflectivity ZDR and copolar correlation coefficient ρhυ linear polarization measurements. Essentially combining information contained in ZDR and ρhυ, CDR-based retrievals of aspect ratios are fairly insensitive to hydrometeor orientation if measurements are performed at elevation angles of around 40°–50°. The suggested approach is applied to data collected using the third ARM Mobile Facility (AMF3), deployed to Oliktok Point, Alaska. Aspect ratio retrievals were also performed using ZDR measurements that are more strongly (compared to CDR) influenced by hydrometeor orientation. The results of radar-based retrievals are compared with in situ measurements from the tethered balloon system (TBS)-based video ice particle sampler and the ground-based multiangle snowflake camera. The observed ice hydrometeors were predominantly irregular-shaped ice crystals and aggregates, with aspect ratios varying between approximately 0.3 and 0.8. The retrievals assume that particle bulk density influencing (besides the particle shape) observed polarimetric variables can be deduced from the estimates of particle characteristic size. Uncertainties of CDR-based aspect ratio retrievals are estimated at about 0.1–0.15. Given these uncertainties, radar-based retrievals generally agreed with in situ measurements. The advantages of using the CDR proxy compared to the linear depolarization ratio are discussed.

Observation of the Pinning-Induced Crystal-Hexatic-Glass Transition in Two-Dimensional Colloidal Suspensions

2021 ◽  
Vol 38 (10) ◽  
pp. 106101
Author(s):  
Xiaoyan Sun ◽  
Huaguang Wang ◽  
Hao Feng ◽  
Zexin Zhang ◽  
Yuqiang Ma
Keyword(s):  
Glass Transition ◽  
Colloidal Suspensions ◽  
Two Dimensional ◽  
Colloidal Systems ◽  
Fundamental Understanding ◽  
New Strategy ◽  
Glassy Materials ◽  
Colloidal Glass ◽  
Orientational Correlation

Identification of the glass formation process in various conditions is of importance for fundamental understanding of the mechanism of glass transitions as well as for developments and applications of glassy materials. We investigate the role of pinning in driving the transformation of crystal into glass in two-dimensional colloidal suspensions of monodisperse microspheres. The pinning is produced by immobilizing a fraction of microspheres on the substrate of sample cells where the mobile microspheres sediment. Structurally, the crystal-hexatic-glass transition occurs with increasing the number fraction of pinning ρ pinning, and the orientational correlation exhibits a change from quasi-long-range to short-range order at ρ pinning = 0.02. Interestingly, the dynamics shows a non-monotonic change with increasing the fraction of pinning. This is due to the competition between the disorder that enhances the dynamics and the pinning that hinders the particle motions. Our work highlights the important role of the pinning on the colloidal glass transition, which not only provides a new strategy to prevent crystallization forming glass, but also is helpful for understanding of the vitrification in colloidal systems.

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

Magnetic tunneling junction based magnetic field sensors: Role of shape anisotropy versus free layer thickness

2011 ◽  
Vol 109 (7) ◽  
pp. 07C731 ◽  
Author(s):  
Lubna R. Shah ◽  
Nupur Bhargava ◽  
Sangcheol Kim ◽  
Ryan Stearrett ◽  
Xiaoming Kou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Layer Thickness ◽  
Shape Anisotropy ◽  
Tunneling Junction ◽  
Free Layer ◽  
Magnetic Field Sensors ◽  
Magnetic Tunneling Junction ◽  
Magnetic Tunneling

Formation of hybrid colloids by suspension polycondensation in the presence of hydrophilic block copolymers

2002 ◽  
Vol 726 ◽  
Author(s):  
Corine Gerardin ◽  
Valérie Buissette ◽  
François Gaudemet ◽  
Olivier Anthony ◽  
Nicolas Sanson ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Colloidal Suspensions ◽  
Surface Charges ◽  
Inorganic Particles ◽  
Hydrous Oxides ◽  
Stabilization Phase ◽  
Metal Ratio ◽  
Forced Hydrolysis ◽  
Hydrolysis Of

AbstractDouble hydrophilic block copolymers were used to control the growth of inorganic particles and directly prepare hybrid colloidal suspensions. Colloids of metal hydrous oxides were obtained by forced hydrolysis of metal ions in presence of the copolymers. The block copolymers contain a metal-complexing polyelectrolyte block and a stabilizing neutral block. The role of the first block is to ensure a controlled growth of the inorganic phase, while simultaneously, the second block ensures the colloidal stabilization. Phase diagrams presenting the conditions under which precipitation is inhibited are established. The nanoparticles are then characterized in terms of sizes, morphologies and surface charges. The main parameters controlling the size were identified: the copolymer-to-metal ratio and the metal prehydrolysis ratio. The synthesis steps were characterized. First, a key step of induced micellization of the hydrophilic copolymers leads to hybrid core-shell assemblies. The second step consists in mineralization of the micellar core. The suspension polycondensation leads to hairy particles whose morphologies depend on the nature of the metal and on synthesis parameters.

scholarly journals Role of growth rate on the orientational alignment of Escherichia coli in a slit

2017 ◽  
Vol 4 (6) ◽  
pp. 170463 ◽  
Author(s):  
Julian Sheats ◽  
Bianca Sclavi ◽  
Marco Cosentino Lagomarsino ◽  
Pietro Cicuta ◽  
Kevin D. Dorfman
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Density Fluctuations ◽  
Global Alignment ◽  
Similar Amount ◽  
Cell Area ◽  
Nematic Ordering ◽  
Side Walls

We present experimental data on the nematic alignment of Escherichia coli bacteria confined in a slit, with an emphasis on the effect of growth rate and corresponding changes in cell aspect ratio. Global alignment with the channel walls arises from the combination of local nematic ordering of nearby cells, induced by cell division and the elongated shape of the cells, and the preferential orientation of cells proximate to the side walls of the slit. Decreasing the growth rate leads to a decrease in alignment with the walls, which is attributed primarily to effects of changing cell aspect ratio rather than changes in the variance in cell area. Decreasing confinement also reduces the degree of alignment by a similar amount as a decrease in the growth rate, but the distribution of the degree of alignment differs. The onset of alignment with the channel walls is coincident with the slits reaching their steady-state occupancy and connected to the re-orientation of locally aligned regions with respect to the walls during density fluctuations.

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