The microscale Weissenberg effect for high-viscosity solution pumping at the picoliter level

Nanoscale ◽  
2018 ◽  
Vol 10 (15) ◽  
pp. 7127-7137 ◽  
Author(s):  
Xuecui Mei ◽  
Qinnan Chen ◽  
Shihu Wang ◽  
Wei Wang ◽  
Dezhi Wu ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Viscosity Solution ◽  
High Viscosity ◽  
Nano Fabrication ◽  
Weissenberg Effect ◽  
Viscous Solutions

Microscale Weissenberg effect based pumping of highly viscous solutions at the picoliter level with a rapid dynamic response is paramount for micro/nano-fabrication.

Evidence of re-entrant behavior in laponite-PEO systems

2005 ◽  
Vol 899 ◽  
Author(s):  
Hossein Baghdadi ◽  
Surita R. Bhatia ◽  
Elizabeth E. C. Jensen ◽  
Nalini Easwar
Keyword(s):  
Molecular Weight ◽  
Viscosity Solution ◽  
High Viscosity ◽  
Polymer Chains ◽  
Low Viscosity ◽  
End Distance ◽  
Depletion Force ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Electrostatic Repulsions

AbstractRheology and dynamic light scattering capture re-entrant behavior of laponite-polymer systems. Neat laponite under basics conditions and concentrations of 2wt% or greater forms a viscoelastic soft glass due to electrostatic repulsions. We show that that addition of low molecular weight poly(ethylene oxide) (PEO) melts the glass due to a depletion force. The depletion force speeds up dynamics in the system resulting in a low viscosity solution. A re-entrant viscoelastic solid is formed with the addition of high molecular weight PEO due to the polymer chains bridging between laponite particles. As expected the transition from a low to high viscosity solution scales with the polymer mean square end-to-end distance and gap between laponite particles.

Dilute bird nectars: viscosity constrains food intake by licking in a sunbird

2010 ◽  
Vol 299 (4) ◽  
pp. R1068-R1074 ◽  
Author(s):  
Angela Köhler ◽  
Carolina D. C. Leseigneur ◽  
Luke Verburgt ◽  
Susan W. Nicolson
Keyword(s):  
Food Intake ◽  
Sucrose Concentration ◽  
Ingestion Rate ◽  
High Viscosity ◽  
Sugar Concentration ◽  
Sucrose Intake ◽  
Total Food Intake ◽  
Total Food ◽  
Sucrose Solutions ◽  
Viscous Solutions

Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds ( Cinnyris talatala ). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar.

Electrospun Fibrous Films with Sub-Micrometer Structure in Biomedical Applications

2011 ◽  
Vol 332-334 ◽  
pp. 977-980
Author(s):  
Chao Feng ◽  
Lu Feng Mo ◽  
Fu Juan Liu
Keyword(s):  
Viscosity Solution ◽  
Biomedical Applications ◽  
High Viscosity ◽  
Manufactured Nanomaterials ◽  
Adverse Impacts ◽  
Viscosity Polymer

Although manufactured nanomaterials have a great many of fantastic functions，the adverse impacts about them have been observed. As a kind of nanomaterial, biomedical films obtained from electrospinning are valued greatly, and the sizes of the diameters in electrospun films plays a fundamental role in enhancing the safety of films. When the diameter of fibers increased to hundreds of nanometers, it will become difficult for fibers to diffuse and infiltrate into human’s body, and then the security of the biomedical films is enhanced greatly. In our work, high viscosity polymer and high viscosity solution are electrospun to increase the diameter of fibers. Besides, melt-eletrospinning is introduced as an alternative candidate for improving the security of biomedical films, especially no poisonous solvent exists.

scholarly journals An Adaptable Device for Scalable Electrospinning of Low- and High-Viscosity Solutions

Instruments ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 37
Author(s):  
McCarty ◽  
Giapis
Keyword(s):  
Relative Humidity ◽  
Liquid Film ◽  
Applied Voltage ◽  
Large Range ◽  
Research Question ◽  
Film Surface ◽  
High Viscosity ◽  
Device Performance ◽  
Rotating Drum ◽  
Viscous Solutions

This paper summarizes the design and construction of an adaptable electrospinner capable of spinning fluids over a large range of viscosities. The design accommodates needless electrospinning technologies and enables researchers to explore a large range of testing parameters. Modular parts can be exchanged for alternative versions that adapt to the research question at hand. A rotating drum electrode immersed halfway into a solution bath provides the liquid film surface from which electrospinning occurs. We tested and assessed several electrode designs and their electrospinning performance at higher (< 500 poise) viscosities. Relative humidity was found to affect the onset of electrospinning of highly viscous solutions. We demonstrate robust device performance at applied voltage up to 90 kV between the electrospinning electrode and the collector. Design and fabrication aspects are discussed in practical terms, with the intent of making this device reproducible in an academic student machine shop.

UHV-STM studies of silicon nano-pyramid growth on silicon surface at high temperature

1992 ◽  
Vol 50 (2) ◽  
pp. 1144-1145
Author(s):  
T. Sato ◽  
S. Kitamura ◽  
T. Sueyoshl ◽  
M. Iwatukl ◽  
C. Nielsen
Keyword(s):  
High Temperature ◽  
Relaxation Process ◽  
Thermal Effect ◽  
Bias Voltage ◽  
Silicon Surface ◽  
Growth Process ◽  
Tunneling Current ◽  
Fabrication Technique ◽  
Nano Fabrication ◽  
Electromigration Effect

Recently, the growth process and relaxation process of crystalline structures were studied by observing a SI nano-pyramid which was built on a Si surface with a UHV-STM. A UHV-STM (JEOL JSTM-4000×V) was used for studying a heated specimen, and the specimen was kept at high temperature during observation. In this study, the nano-fabrication technique utilizing the electromigration effect between the STM tip and the specimen was applied. We observed Si atoms migrated towords the tip on a high temperature Si surface.Clean surfaces of Si(lll)7×7 and Si(001)2×l were prepared In the UHV-STM at a temperature of approximately 600 °C. A Si nano-pyramid was built on the Si surface at a tunneling current of l0nA and a specimen bias voltage of approximately 0V in both polarities. During the formation of the pyramid, Images could not be observed because the tip was stopped on the sample. After the formation was completed, the pyramid Image was observed with the same tip. After Imaging was started again, the relaxation process of the pyramid started due to thermal effect.

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