scholarly journals Formation of double emulsion micro-droplets in a microfluidic device using a partially hydrophilic–hydrophobic surface

RSC Advances ◽  
2021 ◽  
Vol 11 (56) ◽  
pp. 35653-35662
Author(s):  
Ampol Kamnerdsook ◽  
Ekachai Juntasaro ◽  
Numfon Khemthongcharoen ◽  
Mayuree Chanasakulniyom ◽  
Witsaroot Sripumkhai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Frequency Ratio ◽  
Encapsulation Efficiency ◽  
Double Emulsion ◽  
Hydrophobic Surface ◽  
Water Droplets ◽  
Oil In Water ◽  
Rate Ratios ◽  
Frequency Ratios ◽  
Ratio Range

(a) Droplet encapsulation efficiency & inner and outer diameters of water-in-oil-in-water droplets at various frequency ratios and flow rate ratios and (b) Images of water-in-oil-in-water droplets over a frequency-ratio range of fr = 0.73–1.30

Optimization of Droplet Generation by Controlling PDMS Surface Hydrophobicity

2004 ◽  
Author(s):  
Lung-Hsin Hung ◽  
Abraham P. Lee
Keyword(s):  
Hydrophobic Surface ◽  
Surface Hydrophobicity ◽  
Droplet Generation ◽  
Hydrophilic Surface ◽  
Water Droplets ◽  
Pdms Surface ◽  
Oil In Water

This paper presents an optimized method for droplet generation in PDMS microchannels. With controllable PDMS surface hydrophobicity and hydrophobicity recovery, alternative component droplets can be generated as anticipated. Different surface hydrophobicity results in different droplet generation patterns. Monodispersed water-in-oil and oil-in-water droplets are generated from hydrophilic and hydrophobic surface respectively. Nearly hydrophilic surface (30°<θ<50°) results in long-tailed droplets and less hydrophilic surface (70°<θ<80°) results in stream mixing. Discussion of methods to loss and recovery hydrophobicity of PDMS also included.

Exploring the X-ray universe via timing: mass of the active galactic nucleus black hole XMMUJ134736.6+173403

2019 ◽  
Vol 15 (S356) ◽  
pp. 348-350
Author(s):  
Eva Šrámková ◽  
K. Goluchová ◽  
G. Török ◽  
Marek A. Abramowicz ◽  
Z. Stuchlík ◽  
...  
Keyword(s):  
Black Hole ◽  
Frequency Ratio ◽  
Active Galactic Nucleus ◽  
Periodic Modulation ◽  
X Ray ◽  
Upper Limit ◽  
M 10 ◽  
Frequency Ratios ◽  
Quasiperiodic Oscillations ◽  
Twin Peak

AbstractA strong quasi-periodic modulation has recently been revealed in the X-ray flux of the X-ray source XMMUJ134736.6+173403. The two observed twin-peak quasiperiodic oscillations (QPOs) exhibit a 3:1 frequency ratio and strongly support the evidence for the presence of an active galactic nucleus black hole (AGN BH). It has been suggested that detections of twin-peak QPOs with commensurable frequency ratios and scaling of their periods with BH mass could provide the basis for a method intended to determine the mass of BH sources, such as AGNs. Assuming the orbital origin of QPOs, we calculate the upper and lower limit on the AGN BH mass M, reaching M ≍ 107–109M⊙. Compared to mass estimates of other sources, XMMUJ134736.6+173403 appears to be the most massive source with commensurable QPO frequencies, and its mass represents the current observational upper limit on the AGN BH mass obtained from the QPO observations.

scholarly journals Heterogeneous freezing of water droplets containing kaolinite particles

2011 ◽  
Vol 11 (9) ◽  
pp. 4191-4207 ◽  
Author(s):  
B. J. Murray ◽  
S. L. Broadley ◽  
T. W. Wilson ◽  
J. D. Atkinson ◽  
R. H. Wills
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Clay Mineral ◽  
Constant Temperature ◽  
Hydrophobic Surface ◽  
Supercooled Liquid ◽  
Stochastic Approach ◽  
Solid Particles ◽  
Rate Coefficients ◽  
Water Droplets

Abstract. Clouds composed of both ice particles and supercooled liquid water droplets exist at temperatures above ~236 K. These mixed phase clouds, which strongly impact climate, are very sensitive to the presence of solid particles that can catalyse freezing. In this paper we describe experiments to determine the conditions at which the clay mineral kaolinite nucleates ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of kaolinite has been determined as a function of clay surface area, cooling rate and also at constant temperatures. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at rates of between 0.8 and 10 K min−1 or held at constant sub-zero temperatures. The time and temperature at which individual 10–50 μm diameter droplets froze were determined by optical microscopy. For a cooling rate of 10 K min−1, the median nucleation temperature of 10–40 μm diameter droplets increased from close to the homogeneous nucleation limit (236 K) to 240.8 ± 0.6 K as the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt%. This data shows that the probability of freezing scales with surface area of the kaolinite inclusions. We also show that at a constant temperature the number of liquid droplets decreases exponentially as they freeze over time. The constant cooling rate experiments are consistent with the stochastic, singular and modified singular descriptions of heterogeneous nucleation; however, freezing during cooling and at constant temperature can be reconciled best with the stochastic approach. We report temperature dependent nucleation rate coefficients (nucleation events per unit time per unit area) for kaolinite and present a general parameterisation for immersion nucleation which may be suitable for cloud modelling once nucleation by other important ice nucleating species is quantified in the future.

Magnetofluidic control of the breakup of ferrofluid droplets in a microfluidic Y-junction

RSC Advances ◽  
2016 ◽  
Vol 6 (1) ◽  
pp. 778-785 ◽  
Author(s):  
Huajun Li ◽  
Yining Wu ◽  
Xiaoda Wang ◽  
Chunying Zhu ◽  
Taotao Fu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Rate Ratios

Breakup of the ferrofluid droplets at the Y-junction divergence under various flow rate ratios.

Biodegradable polymers-based nanoparticles to enhance the antifungal efficacy of fluconazole against Candida albicans

2021 ◽  
Vol 22 ◽  
Author(s):  
Noha Saleh ◽  
Soha Elshaer ◽  
Germeen Girgis
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Encapsulation Efficiency ◽  
Water Solubility ◽  
In Vitro Release ◽  
Double Emulsion ◽  
Dilution Method ◽  
Ft Ir ◽  
Antifungal Efficacy

Background: Fluconazole (FLZ), a potent antifungal medication, is characterized by poor water solubility that reduced its antifungal efficacy. Objective: This study aimed to prepare FLZ-loaded polymeric nanoparticles (NPs) by using different polymers and techniques as a mean of enhancing the antifungal activity of FLZ. Methods: NP1, NP2, and NP3 were prepared by the double emulsion/solvent evaporation method using PLGA, PCL, and PLA, respectively. The ionotropic pre-gelation technique was applied to prepare an alginate/chitosan-based formulation (NP4). Particle size, zeta potential, encapsulation efficiency, and loading capacity were characterized. FT-IR spectra of FLZ, the polymers, and the prepared NPs were estimated. NP4 was selected for further in-vitro release evaluation. The broth dilution method was used to assess the antifungal activity of NP4 using a resistant clinical isolate of Candida albicans. Results: The double emulsion method produced smaller-sized particles (<390 nm) but with much lower encapsulation efficiency (< 12%). Alternatively, the ionic gelation method resulted in nanosized particles with a markedly higher encapsulation efficiency of about 40%. The FT-IR spectroscopy confirmed the loading of the FLZ molecules in the polymeric network of the prepared NPs. The release profile of NP4 showed a burst initial release followed by a controlled pattern up to 24 hours with a higher percent released relative to the free FLZ suspension. NP4 was able to reduce the value of MIC of FLZ by 20 times. Conclusion: The antifungal activity of FLZ against C. albicans was enhanced markedly via its loading in the alginate/chitosan-based polymeric matrix of NP4.

scholarly journals Microencapsulation of Purple Cactus Pear Fruit (Opuntia ficus indica) Extract by the Combined Method W/O/W Double Emulsion-Spray Drying and Conventional Spray Drying: A Comparative Study

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 189 ◽  
Author(s):  
Keren Toledo-Madrid ◽  
Tzayhrí Gallardo-Velázquez ◽  
Guillermo Osorio-Revilla
Keyword(s):  
Spray Drying ◽  
Desirability Function ◽  
Double Emulsion ◽  
Dry Weight ◽  
Antioxidant Compounds ◽  
Pear Fruit ◽  
Cactus Pear ◽  
Opuntia Ficus Indica ◽  
Globule Size ◽  
Oil In Water

The aim of this study was to microencapsulate an optimized extract of purple cactus pear fruit (Opuntia ficus indica), rich in phenolic compounds (PC), betacyanins (BC), and betaxanthins (BX), with antioxidant capacity (AC), by two methodologies: combined water-in-oil-in water double emulsions-spray drying (W/O/W-SP) and conventional spray drying, studying the effect of spray drying (SP) on PC and AC. Optimal extraction conditions for bioactive compounds were: 52 °C, for 30 min, using aqueous ethanol (40%) as the solvent, with a 0.85 desirability function, obtaining 17.39 ± 0.11 mg GAE/gdw (gallic acid equivalents per gram of dry weight) for PC, 0.35 mg BE/gdw (betanin equivalents per gram of dry weight) for BC, and 0.26 mg IE/gdw (indicaxanthin equivalents per gram of dry weight) for BX. The best combination of temperatures for conventional SP and W/O/W-SP was 160–80 °C obtaining the highest retention and encapsulation efficiencies for PC. For conventional SP, results were: 107% and 100% PC and AC retention efficiencies (RE-PC and RE-AC), respectively, with 97% of PC encapsulation efficiency (EE-PC), meanwhile for the W/O/W-SP results were: 78% and 103% RE-PC and RE-AC, respectively, with 70% of EE-PC. Microcapsules obtained with W/O/W-SP maintained their structure and integrity and showed a considerable reduction in globule size in the reconstituted W/O/W emulsions due to the spray drying stress. Despite having lower EE-PC than conventional SP, spray dried W/O/W emulsions seems to be a promising controlled-delivery vehicle for antioxidant compounds.

scholarly journals Revising the musical equal temperament

2016 ◽  
Vol 38 (1) ◽  
Author(s):  
Haye Hinrichsen
Keyword(s):  
Nineteenth Century ◽  
Frequency Ratio ◽  
Western Music ◽  
Equal Temperament ◽  
Frequency Ratios ◽  
High Degree

Western music is predominantly based on the equal temperament with a constant semitone frequency ratio of 21/12. Although this temperament has been in use since the nineteenth century and in spite of its high degree of symmetry, various musicians have repeatedly expressed their discomfort with the harmonicity of certain intervals. Recently it was suggested that this problem can be overcome by introducing a modified temperament with a constant but slightly increased frequency ratio. In this paper we confirm this conjecture quantitatively. Using entropy as a measure for harmonicity, we show numerically that the harmonic optimum is in fact obtained for frequency ratios slightly larger than 21/12. This suggests that the equal temperament should be replaced by a harmonized stretched temperament as a new standard.

scholarly journals Development of oil-in-water microemulsion encapsulating Vitamin E for thermal and hydrolysis degradation study

2020 ◽  
Vol 16 (3) ◽  
pp. 277-280
Author(s):  
Khairun Nisa Abdul Rahman ◽  
Vicit Rizal Eh Suk ◽  
Khalisanni Khalid ◽  
Nurhazirah Mohd Ihsan ◽  
Zainurin Md Dom ◽  
...  
Keyword(s):  
Particle Size ◽  
Vitamin E ◽  
Encapsulation Efficiency ◽  
Low Cost ◽  
Bioactive Compound ◽  
Small Particle Size ◽  
Degradation Study ◽  
Oil In Water ◽  
The Mean ◽  
Vitamin E Homologs

Vitamin E is widely used for medicinal and cosmeceuticals purposes. However, it is easy to degrade by the environment. In this study, the degradation of Gold Tri.E™ was studied and determined. Gold Tri.E™ is a mixture of Vitamin E homologs (tocotrienol and tocopherol) extracted from palm oil (Elais Guineensis). A nanocarrier system has been optimized to encapsulate Gold Tri.E™ from degrading and increasing its stability as a bioactive compound. An oil-in-water (o/w) microemulsion was formulated and optimized as the best carrier to encapsulate Gold Tri.E™ with the mean particle size of 32.60±3.60 nm and 99.99±0.01% encapsulation efficiency (EE). Degradation of the Gold Tri.E™ in o/w microemulsion was significantly reduced as compared to the bare Gold Tri.ETM. This suggested that the system could protect Gold Tri.E™ from thermal and hydrolysis degradation. Thus, the ease of preparation, low-cost production, and small particle size obtained when Gold Tri.E™ encapsulated in this system give promising drug delivery system to encapsulate, protect, and increase the shelf life of Gold Tri.E™.

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