scholarly journals Empirical Size Corrections for Shadowgraph Imaging of Non-Spherical Droplets

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Chad Sipperley ◽  
Kyle Bade ◽  
Paul Vesely ◽  
Rudolf Schick
Keyword(s):  
Spherical Droplets ◽  
Empirical Size

Combination of Microemulsion for Topical Deliverying Tripterygium Wilfordii Multiglycoside

2011 ◽  
Vol 694 ◽  
pp. 881-885
Author(s):  
Xin He ◽  
Xing Hua Zhao ◽  
Wu Qing Ou Yang
Keyword(s):  
Immune Suppression ◽  
Topical Delivery ◽  
Skin Permeability ◽  
Tripterygium Wilfordii ◽  
Delivery Vehicle ◽  
Control Solution ◽  
Suppression Effect ◽  
Low Viscosity ◽  
Spherical Droplets

The purpose of this study was to explore the potential application of the combination of microemulsion as a topical delivery vehicle in enhancing the absorption and efficacy of tripterygium wilfordii multiglycoside (TWM). Various microemulsion formulations were developed and an optimal microemulsion (TWM-ME)，which presented spherical droplets and consisted of RH-40, IPM and water was 27: 3.3: 69.7 by weight. It possessd an average droplet size of 23.6 nm, a low viscosity of (3.56±0.12) mm2•s-1 Zeta electric potential was (–5.35±0.42) mV, refractive index was (1.3617±0.0051) nD20, conductivity was (97.6±3.6) μs/cm. Compared to the control solution, TWM-ME provided better skin permeability in vitro. Moreover, TWM-ME has noticeable anti-inflammatory and immune suppression effect. These results indicate that the combination of microemulsion represents an effective vehicle for topical delivery of TWM.

scholarly journals BslA-stabilized emulsion droplets with designed microstructure

2017 ◽  
Vol 7 (4) ◽  
pp. 20160124 ◽  
Author(s):  
Keith M. Bromley ◽  
Cait E. MacPhee
Keyword(s):  
Structural Integrity ◽  
Melting Process ◽  
Continuous Phase ◽  
Central Component ◽  
Emulsion Droplet ◽  
Emulsion Droplets ◽  
Elastic Film ◽  
Air Water Interface ◽  
Droplet Morphology ◽  
Spherical Droplets

Emulsions are a central component of many modern formulations in food, pharmaceuticals, agrichemicals and personal care products. The droplets in these formulations are limited to being spherical as a consequence of the interfacial tension between the dispersed phase and continuous phase. The ability to control emulsion droplet morphology and stabilize non-spherical droplets would enable the modification of emulsion properties such as stability, substrate binding, delivery rate and rheology. One way of controlling droplet microstructure is to apply an elastic film around the droplet to prevent it from relaxing into a sphere. We have previously shown that BslA, an interfacial protein produced by the bacterial genus Bacillus , forms an elastic film when exposed to an oil- or air–water interface. Here, we highlight BslA's ability to stabilize anisotropic emulsion droplets. First, we show that BslA is capable of arresting dynamic emulsification processes leading to emulsions with variable morphologies depending on the conditions and emulsification technique applied. We then show that frozen emulsion droplets can be manipulated to induce partial coalescence. The structure of the partially coalesced droplets is retained after melting, but only when there is sufficient free BslA in the continuous phase. That the fidelity of replication can be tuned by adjusting the amount of free BslA in solution suggests that freezing BslA-stabilized droplets disrupts the BslA film. Finally, we use BslA's ability to preserve emulsion droplet structural integrity throughout the melting process to design emulsion droplets with a chosen shape and size.

scholarly journals Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

2010 ◽  
Vol 10 (12) ◽  
pp. 5685-5705 ◽  
Author(s):  
X. Wang ◽  
L. Zhang ◽  
M. D. Moran
Keyword(s):  
Size Distribution ◽  
Collection Efficiency ◽  
Theoretical Calculations ◽  
Terminal Velocity ◽  
Moderate Intensity ◽  
Size Spectrum ◽  
Cloud Particle ◽  
Particle Collection ◽  
Particle Scavenging ◽  
Empirical Size

Abstract. Current theoretical and empirical size-resolved parameterizations of the scavenging coefficient (Λ), a parameter commonly used in aerosol transport models to describe below-cloud particle scavenging by rain, have been reviewed in detail and compared with available field and laboratory measurements. Use of different formulations for raindrop-particle collection efficiency can cause uncertainties in size-resolved Λ values of one to two orders of magnitude for particles in the 0.01–3 μm diameter range. Use of different formulations of raindrop number size distribution can cause Λ values to vary by a factor of 3 to 5 for all particle sizes. The uncertainty in Λ caused by the use of different droplet terminal velocity formulations is generally small than a factor of 2. The combined uncertainty due to the use of different formulations of raindrop-particle collection efficiency, raindrop size spectrum, and raindrop terminal velocity in the current theoretical framework is not sufficient to explain the one to two order of magnitude under-prediction of Λ for the theoretical calculations relative to the majority of field measurements. These large discrepancies are likely caused by additional known physical processes (i.e, turbulent transport and mixing, cloud and aerosol microphysics) that influence field data but that are not considered in current theoretical Λ parameterizations. The predicted size-resolved particle concentrations using different theoretical Λ parameterization can differ by up to a factor of 2 for particles smaller than 0.01 μm and by a factor of >10 for particles larger than 3 μm after 2–5 mm of rain. The predicted bulk mass and number concentrations (integrated over the particle size distribution) can differ by a factor of 2 between theoretical and empirical Λ parameterizations after 2–5 mm of moderate intensity rainfall.

The effective viscosity for an emulsion of spherical droplets

1989 ◽  
Vol 131 (2) ◽  
pp. 596-597
Author(s):  
Kamen Panayotov Dimitrov ◽  
Boryan Penkov Radoev
Keyword(s):  
Effective Viscosity ◽  
Spherical Droplets

scholarly journals A regression error specification test (RESET) for the truncated regression model

2018 ◽  
Vol 6 (2) ◽  
pp. 53 ◽  
Author(s):  
Sunil Sapra
Keyword(s):  
Linear Regression ◽  
Regression Model ◽  
Linear Regression Model ◽  
Truncated Regression ◽  
Specification Test ◽  
Specification Tests ◽  
Monte Carlo Experiments ◽  
Regression Error ◽  
Empirical Size ◽  
Power Properties

While a variety of specification tests are routinely employed to test for misspecification in linear regression model, such tests and their applications to the truncated and censored regression models are uncommon. This paper develops a regression error specification test (RESET) for the truncated regression model as an extension of the popular RESET for the linear regression model (Ramsey (1969)). The two proposed extensions TRESET1 and TRESET2 developed in the paper are applied to labor force participation data from Mroz (1987). The paper studies the empirical size and power properties of the proposed tests via Monte Carlo experiments. Our simulation results suggest that both TRESET tests have reasonably good size and power properties for the truncated regression model in medium to large samples. However, TRESET2 consistently outperforms TRESET1 both in terms of empirical size and power in our experiments.  

A Robust Test for Monotonicity in Asset Returns

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Cleiton G. Taufemback ◽  
Victor Troster ◽  
Muhammad Shahbaz
Keyword(s):  
General Setting ◽  
Asset Returns ◽  
Conditional Heteroskedasticity ◽  
Test Statistic ◽  
Robust Test ◽  
Type 1 Error ◽  
Heavy Tailed Distributions ◽  
Heavy Tailed ◽  
Empirical Size

Abstract In this paper, we propose a robust test of monotonicity in asset returns that is valid under a general setting. We develop a test that allows for dependent data and is robust to conditional heteroskedasticity or heavy-tailed distributions of return differentials. Many postulated theories in economics and finance assume monotonic relationships between expected asset returns and certain underlying characteristics of an asset. Existing tests in literature fail to control the probability of a type 1 error or have low power under heavy-tailed distributions of return differentials. Monte Carlo simulations illustrate that our test statistic has a correct empirical size under all data-generating processes together with a similar power to other tests. Conversely, alternative tests are nonconservative under conditional heteroskedasticity or heavy-tailed distributions of return differentials. We also present an empirical application on the monotonicity of returns on various portfolios sorts that highlights the usefulness of our approach.

scholarly journals Jetting Performance of Polyethylene Glycol and Reactive Dye Solutions

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 739 ◽  
Author(s):  
Zhiyuan Tang ◽  
Kuanjun Fang ◽  
Yawei Song ◽  
Fuyun Sun
Keyword(s):  
Surface Tension ◽  
Polyethylene Glycol ◽  
Production Efficiency ◽  
Hydrophobic Interactions ◽  
Reactive Dye ◽  
Droplet Formation ◽  
Visible Absorption ◽  
Fluid Behavior ◽  
Spherical Droplets ◽  
Dye Solutions

The jetting performance of dye inks determines the image quality, production efficiency, and lifetime of the print head. In the present study, we explored the jetting performance of mixed solutions of polyethylene glycol (PEG) and reactive dye by testing the visible absorption spectra, rheological properties, and surface tension, in addition to the observation of droplet formation. The results indicate that PEG macromolecules could change the aggregate groups of Red 218 molecules into smaller ones through hydrophobic interactions and separation effect. The addition of PEG into the dye solution increased the viscosity and decreased the surface tension. In the whole shear rate range tested, the 10% and 20% PEG400, as well as the 30% PEG200 dye solutions, showed good Newtonian fluid behavior. PEG macromolecules improved the droplet formation of the dye solutions. Increasing the PEG400 concentration to 30% and 40% resulted in elimination of the formation of satellites and the formation of ideal droplets at 10,000 Hz jetting frequency. A 30% PEG600-dye solution with the Z value of 4.6 formed the best spherical droplets at 10,000 Hz and produced perfect color images on cotton fabrics.

scholarly journals DEVELOPMENT OF SELF NANO-EMULSIFYING DRUG DELIVERY SYSTEM FOR AN ANTI-HYPERTENSIVE AGENT FELODIPINE: A SYSTEMATIC APPROACH FOR LIPID NANO-FORMULATION WITH IMPROVED ORAL BIOAVAILABILITY IN RATS

2020 ◽  
pp. 86-94
Author(s):  
K. TRIDEVA SASTRI ◽  
G. V. RADHA
Keyword(s):  
Droplet Size ◽  
Aqueous Solubility ◽  
Bioavailability Enhancement ◽  
Cinnamon Oil ◽  
Stability Robustness ◽  
Tween 60 ◽  
Spherical Droplets ◽  
Nano Formulation

Objective: The present study involves the development of SNEDDS employing essential oils for enhancing biopharmaceutical performance. Methods: Preliminary investigations suggested the selection of cinnamon oil as an essential oil, tween 60 as a surfactant, while transcutol HP as a cosolvent for formulating SNEDDS. Formulations evaluated for stability, robustness to dilution, and emulsification time, droplet size, zeta potential (ζ), cloud point, in vitro drug release, drug excipient compatibility, TEM, stability assessment and in vivo pharmacokinetic performance in rats. Results: All formulations were robust, stable, and revealed excellent emulsification time<40 s, with fine droplet size (11.41±2.41 nm), lower PDI (0.028-0.277). Formulation F(FLD)6 exhibited a release of 97.7% within 4h, and TEM photograph confirmed spherical droplets. The bioavailability results revealed a higher rate and extent of absorption, AUC, and Cmax for the formulations found to be 1212.4 and 355.40±13.67 (p<0.05). The results recommend that the developed formulation approach offers bioavailability enhancement of FLD. Conclusion: The study concluded that SNEDDS would be an effective formulation system in increasing the aqueous solubility and potentially bioavailability. Furthermore, it can be applied for other therapeutic categories of drugs belonging to BCS class II and IV that show comparable biopharmaceutical challenges.

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