Vibrations of axially traveling plates partially coupled with a viscous, orthogonally flowing liquid

2021 ◽  
Author(s):  
Han Wu ◽  
Feng Liu Yang ◽  
Yan Qing Wang
Keyword(s):  
Flowing Liquid

NUCLEATE BOILING IN A FLOWING LIQUID

1970 ◽  
Author(s):  
G. H. Anderson ◽  
D.E. Minns
Keyword(s):  
Nucleate Boiling ◽  
Flowing Liquid

MODELING OF NONLINEAR VIBRATION PROBLEMS WITH FLUID FLOWS THROUGH PIPELINES

2018 ◽  
pp. 44-47
Author(s):  
F.J. Тurayev
Keyword(s):  
Differential Equations ◽  
Nonlinear Vibration ◽  
Viscoelastic Properties ◽  
Construction Material ◽  
Fluid Flows ◽  
Variable Coefficients ◽  
Algebraic Equations ◽  
Flowing Liquid ◽  
Vibration Problems

In this paper, mathematical model of nonlinear vibration problems with fluid flows through pipelines have been developed. Using the Bubnov–Galerkin method for the boundary conditions, the resulting nonlinear integro-differential equations with partial derivatives are reduced to solving systems of nonlinear ordinary integro-differential equations with both constant and variable coefficients as functions of time.A system of algebraic equations is obtained according to numerical method for the unknowns. The influence of the singularity of heredity kernels on the vibrations of structures possessing viscoelastic properties is numerically investigated.It was found that the determination of the effect of viscoelastic properties of the construction material on vibrations of the pipeline with a flowing liquid requires applying weakly singular hereditary kernels with an Abel type singularity.

Enhanced Skin Permeation of Punicalagin after Topical Application of Pluronic Micelles or Vesicles Loaded with Lafoensia pacari Extract

Planta Medica ◽  
2021 ◽  
Author(s):  
Sandra Alves de Sousa Garcia ◽  
Priscila Bianca Rodrigues da Rocha ◽  
Bruno dos Santos Souza ◽  
Andressa Tuane Santana Paz ◽  
Ana Luiza Caetano Negris ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Skin Permeation ◽  
Sol Gel ◽  
Extraction Procedure ◽  
Average Diameter ◽  
Skin Aging ◽  
Chemical Degradation ◽  
Vertical Diffusion ◽  
Flowing Liquid ◽  
Span 80

AbstractPunicalagin, the principal ellagitannin of Lafoensia pacari leaves, has proven antioxidant activity, and standardized extracts of L. pacari can be topically used for skin aging management. We hypothesized that Pluronic nanomicelles or vesicles could solubilize sufficiently large amounts of the standardized extracts of L. pacari and provide chemical stability to punicalagin. The standardized extracts of L. pacari were obtained with an optimized extraction procedure, and the antioxidant activity was characterized. Formulations containing Pluronic at 25% and 35% were obtained with or without Span 80. They were characterized by average diameter, polydispersity index, punicalagin content, physicochemical stability, and rheology. A release and skin permeation study was carried out in vertical diffusion cells. The extraction procedure allowed quantifying high punicalagin content (i.e., 141.61 ± 3.87 mg/g). The standardized extracts of L. pacari showed antioxidant activity for all evaluated methods. Pluronic at 25 and Pluronic at 35 with standardized extracts of L. pacari showed an average diameter of about 25 nm. The addition of Span 80 significantly increased the mean diameter by 15-fold (p < 0.05), indicating the spontaneous formation of vesicles. Pluronic formulations significantly protected punicalagin from chemical degradation (p < 0.05). Pluronic at 25 formulations presented as free-flowing liquid-like systems, while Pluronic at 35 resulted in an increase of about 44-fold in |ƞ*|. The addition of Span 80 significantly reduced the Pluronic sol-gel transition temperature (p < 0.05), indicating the formation of vesicles. Formulations with Span 80 significantly enhanced punicalagin skin permeation compared to formulations without Span 80 (p < 0.05). Formulations with Span 80 were demonstrated to be the most promising formulations, as they allowed significant permeation of punicalagin (about 80 to 315 µg/cm2), which has been shown to have antioxidant activity.

Simplified and rapid determination of Ca, K, Mg, and Na in fruit juices by flowing liquid cathode atmospheric glow discharge optical emission spectrometry

2021 ◽  
Author(s):  
Monika Gorska ◽  
Pawel Pohl
Keyword(s):  
Glow Discharge ◽  
Rapid Determination ◽  
Optical Emission ◽  
Fruit Juices ◽  
Emission Spectrometry ◽  
Atmospheric Pressure Glow Discharge ◽  
Flowing Liquid ◽  
Liquid Cathode ◽  
Pressure Glow Discharge

Atmospheric pressure glow discharge (APGD) microplasma, sustained between a flowing liquid cathode (FLC) and a tungsten anode, was applied for the determination of Ca, K, Mg, and Na in fruit juices with a simplified sample preparation procedure.

Synchrotron infrared microspectroscopy reveals the response of Sphagnum cell wall material to its aqueous chemical environment

2018 ◽  
Vol 15 (8) ◽  
pp. 513
Author(s):  
Ewen Silvester ◽  
Annaleise R. Klein ◽  
Kerry L. Whitworth ◽  
Ljiljana Puskar ◽  
Mark J. Tobin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Chemical Environment ◽  
Wall Material ◽  
Organic Soils ◽  
Cell Wall Material ◽  
Acid Base ◽  
Widespread Species ◽  
Flowing Liquid ◽  
Infrared Microspectroscopy

Environmental contextSphagnum moss is a widespread species in peatlands globally and responsible for a large fraction of carbon storage in these systems. We used synchrotron infrared microspectroscopy to characterise the acid-base properties of Sphagnum moss and the conditions under which calcium uptake can occur (essential for plant tissue integrity). The work allows a chemical model for Sphagnum distribution in the landscape to be proposed. AbstractSphagnum is one the major moss types responsible for the deposition of organic soils in peatland systems. The cell walls of this moss have a high proportion of carboxylated polysaccharides (polygalacturonic acids), which act as ion exchangers and are likely to be important for the structural integrity of the cell walls. We used synchrotron light source infrared microspectroscopy to characterise the acid-base and calcium complexation properties of the cell walls of Sphagnum cristatum stems, using freshly sectioned tissue confined in a flowing liquid cell with both normal water and D2O media. The Fourier transform infrared spectra of acid and base forms are consistent with those expected for protonated and deprotonated aliphatic carboxylic acids (such as uronic acids). Spectral deconvolution shows that the dominant aliphatic carboxylic groups in this material behave as a monoprotic acid (pKa=4.97–6.04). The cell wall material shows a high affinity for calcium, with a binding constant (K) in the range 103.9–104.7 (1:1 complex). The chemical complexation model developed here allows for the prediction of the chemical environment (e.g. pH, ionic content) under which Ca2+ uptake can occur, and provides an improved understanding for the observed distribution of Sphagnum in the landscape.

Electroviscous forces on a charged particle suspended in a flowing liquid

1997 ◽  
Vol 338 ◽  
pp. 1-34 ◽  
Author(s):  
R. G. COX
Keyword(s):  
Particle Size ◽  
Physical Mechanism ◽  
Aqueous Electrolyte ◽  
Complete Agreement ◽  
Dominant Contribution ◽  
General Shape ◽  
Flowing Liquid ◽  
Polar Fluid ◽  
Double Layer Thickness ◽  
Made In

The force on a charged solid particle (of general shape) suspended in a flowing polar fluid (e.g. an aqueous electrolyte solution) in the presence of a solid bounding wall (of general shape) is obtained for the situation in which the electrical double-layer thickness is very much smaller than the particle size (and the distance between particle and wall). The very general results so obtained are applied to the sedimentation of a charged spherical particle in an unbounded polar fluid (with no walls present) for which the drag force is found to be in complete agreement with Ohshima et al. (1984). However, there is disagreement between the present results and those obtained in a number of published papers owing to incorrect assumptions being made in the latter as to what physical mechanism gives rise to the dominant contribution to the electroviscous force on the particle.

Liquid encapsulated electrostatic energy harvester for low-frequency vibrations

2012 ◽  
Vol 24 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Ling Bu ◽  
Xiaoming Wu ◽  
Xiaohong Wang ◽  
Litian Liu
Keyword(s):  
Polyvinylidene Fluoride ◽  
Output Voltage ◽  
Energy Harvester ◽  
Low Frequency ◽  
Electrostatic Energy ◽  
Maximum Output ◽  
Flowing Liquid ◽  
Horizontal Vibration ◽  
Low Viscosity ◽  
High Relative Permittivity

This article presents the modeling, fabrication, and testing of liquid encapsulated energy harvester using polyvinylidene fluoride electrets. Unlike harvesters reported in previous literature, this liquid encapsulated energy harvester uses flowing liquid rather than conventional resonating structures to induce variable capacitance and is more suitable for low-frequency applications. Prototypes injected with three types of liquid ( N-methyl-2-pyrrolidone, N, N-dimethylformamide, and glycerin) are tested in horizontal vibration and rotary motion mode, respectively. The results show that N, N-dimethylformamide–injected prototypes display the most desirable performance in horizontal vibration testing at 1–10 Hz due to high relative permittivity and low viscosity, with maximum output voltage of 2.32 V and power of 0.18 µW at 10 Hz. Glycerin-injected prototypes perform best at 0.1–1 Hz rotation due to effective movement and highest permittivity, with maximum output voltage of 11.46 V and power of 2.19 µW at 1 Hz.

Laminar Fully-Developed Flow in a Microchannel With Patterned Ultrahydrophobic Walls

2005 ◽  
Author(s):  
B. Woolford ◽  
K. Jeffs ◽  
D. Maynes ◽  
B. W. Webb
Keyword(s):  
Pressure Drop ◽  
Solid Wall ◽  
Relative Size ◽  
Frictional Resistance ◽  
Hydraulic Diameter ◽  
Fourth Power ◽  
Fully Developed Flow ◽  
Flowing Liquid ◽  
Frictional Pressure Drop ◽  
Liquid Vapor

Microfluidic transport is finding increasing application in a number of emerging technologies. At these scales, classical analysis shows that the required fluid driving pressure is inversely proportional to the hydraulic diameter to the fourth power. Consequently, generating fluid motion at these physical scales is a challenge. There is thus considerable incentive for developing strategies to reduce the frictional resistance to fluid flow. A novel approach recently proposed is fabrication of micro-ribs and cavities in the channel walls which are treated with a hydrophobic coating. This reduces the surface contact area between the flowing liquid and the solid wall, yielding walls with no-slip and shear-free regions at the microscale. The shear-free regions consist of a liquid-vapor meniscus above the cavities between micro-ribs. Reductions in the flow resistance are thus possible. This paper reports results of an analytical and experimental investigation of the laminar, fully-developed flow in a parallel plate microchannel whose walls are microengineered in this fashion. The micro-ribs and cavities are oriented parallel to the flow direction. The channel walls are modeled in an idealized fashion, with the shape of liquid-vapor meniscus approximated as flat and characterized by vanishing shear stress. Predictions are presented for the friction factor-Reynolds number product as a function of relevant governing dimensionless parameters. Comparisons are made between the smooth-wall classical channel flow results and predictions for the microengineered channel walls. Results show that significant reductions in the frictional pressure drop are possible. Reductions in frictional resistance increase as the channel hydraulic diameter and/or micro-rib width are reduced. The frictional pressure drop predictions are in good agreement with experimental measurements made at dynamically similar conditions, with greater deviation observed with increasing relative size of the shear-free regions.

Sign in / Sign up

Export Citation Format

Share Document