scholarly journals Rheological and droplet size analysis of W/O/W multiple emulsions containing low concentrations of polymeric emulsifiers

2009 ◽  
Vol 74 (7) ◽  
pp. 801-816 ◽  
Author(s):  
Dragana Vasiljevic ◽  
Jelena Parojcic ◽  
Marija Primorac ◽  
Gordana Vuleta
Keyword(s):  
Droplet Size ◽  
Size Analysis ◽  
Multiple Emulsion ◽  
Multiple Emulsions ◽  
Breakdown Mechanism ◽  
Low Concentrations ◽  
Dispersion Systems ◽  
Potential Applications ◽  
Polymeric Emulsifier ◽  
Polymeric Emulsifiers

Multiple emulsions are complex dispersion systems which have many potential applications in pharmaceutics, cosmetics and the food industry. In practice, however, significant problems may arise because of their thermodynamic instability. In this study, W/O/W multiple emulsion systems containing low concentration levels of lipophilic polymeric primary emulsifiers cetyl dimethicone copolyol and PEG-30 dipolyhydroxystearate were evaluated. The concentrations of the primary emulsifiers were set at 1.6 and 2.4 % w/w in the final emulsions. Rheological and droplet size analysis of the investigated samples showed that the type and concentration of the primary lipophilic polymeric emulsifier markedly affected the characteristics of the multiple emulsions. The multiple emulsion prepared with 2.4 % w/w PEG-30 dipolyhydroxystearate as the primary emulsifier exhibited the highest apparent viscosity, yield stress and elastic modulus values, as well as the smallest droplet size. Furthermore, these parameters remained relatively constant over the study period, confirming the high stability of the investigated sample. The results obtained indicate that the changes observed in the investigated samples over time could be attributed to the swelling/breakdown mechanism of the multiple droplets. Such changes could be adequately monitored by rheological and droplet size analysis.

scholarly journals DEVELOPMENT OF MICROEMULSION AND WATER/OIL/WATER MULTIPLE EMULSION CONTAINING BETA-ARBUTIN, LACTIC ACID, AND SODIUM ASCORBYL PHOSPHATE

2020 ◽  
pp. 212-220
Author(s):  
SILVIA SURINI ◽  
NUR MPN NEGORO
Keyword(s):  
Lactic Acid ◽  
Droplet Size ◽  
Physical Stability ◽  
Continuous Phase ◽  
Stability Studies ◽  
Flow Properties ◽  
Multiple Emulsion ◽  
Multiple Emulsions ◽  
Whitening Agent ◽  
Oil Water

Objective: In addition to lactic acid and sodium ascorbyl phosphate, which have whitening effects, beta-arbutin is a safe whitening agent for skin.Combining these three substances should reduce the concentration of each one in a formula and achieve an optimal whitening effect. In this study,microemulsions and water/oil/water (W/O/W) multiple emulsions were applied to produce a formula containing these whitening agents.Methods: All the active ingredients were formulated into microemulsions and W/O/W multiple emulsions with different concentrations of Tween 80and Span 80 as emulsifiers to obtain a stable formula. Twelve-week physical stability studies were performed for every formula at low (4±2°C), room(28±2°C), and high (40±2°C) temperatures.Results: The produced microemulsions were transparent with a mean droplet size of 15.50 nm. In addition, the W/O/W multiple emulsions containeddroplets within droplets, which were dispersed in a continuous phase with an inner droplet size of 0.15 μm and an outer droplet size of 0.37 μm. TheW/O/W multiple emulsions showed pseudoplastic thixotropic flow properties. Furthermore, the microemulsions were stable at low (4±2°C) androom (28±2°C) temperatures, while the W/O/W multiple emulsions were stable at room (28±2°C) and high (40±2°C) temperatures.Conclusion: It was concluded that the combination of beta-arbutin, lactic acid, and sodium ascorbyl phosphate was suitable for formulating intomicroemulsions as well as W/O/W multiple emulsions as whitening cosmetic products.

scholarly journals Geochemical and Mineralogical Characterisation of Historic Zn–Pb Mine Waste, Plombières, East Belgium

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 28
Author(s):  
Srećko Bevandić ◽  
Rosie Blannin ◽  
Jacqueline Vander Auwera ◽  
Nicolas Delmelle ◽  
David Caterina ◽  
...  
Keyword(s):  
Grain Size ◽  
Mine Waste ◽  
Geophysical Methods ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Mine Wastes ◽  
Metallurgical Waste ◽  
High Concentration ◽  
Geochemical Properties ◽  
Potential Applications

Mine wastes and tailings derived from historical processing may contain significant contents of valuable metals due to processing being less efficient in the past. The Plombières tailings pond in eastern Belgium was selected as a case study to determine mineralogical and geochemical characteristics of the different mine waste materials found at the site. Four types of material were classified: soil, metallurgical waste, brown tailings and yellow tailings. The distribution of the mine wastes was investigated with drill holes, pit-holes and geophysical methods. Samples of the materials were assessed with grain size analysis, and mineralogical and geochemical techniques. The mine wastes dominantly consist of SiO2, Al2O3 and Fe2O3. The cover material, comprising soil and metallurgical waste is highly heterogeneous in terms of mineralogy, geochemistry and grain size. The metallurgical waste has a high concentration of metals (Zn: 0.1 to 24 wt.% and Pb: 0.1 to 10.1 wt.%). In the tailings materials, Pb and Zn vary from 10 ppm to 8.5 wt.% and from 51 ppm to 4 wt.%, respectively. The mining wastes comprises mainly quartz, amorphous phases and phyllosilicates, with minor contents of Fe-oxide and Pb- and Zn-bearing minerals. Based on the mineralogical and geochemical properties, the different potential applications of the four waste material types were determined. Additionally, the theoretical economic potential of Pb and Zn in the mine wastes was estimated.

scholarly journals Fabrication, physicochemical characterization and preliminary efficacy evaluation of a W/O/W multiple emulsion loaded with 5% green tea extract

2013 ◽  
Vol 49 (2) ◽  
pp. 341-349 ◽  
Author(s):  
Tariq Mahmood ◽  
Naveed Akhtar ◽  
Barkat Ali Khan ◽  
Akhtar Rasul ◽  
Haji M. Shoaib Khan
Keyword(s):  
Green Tea ◽  
Storage Conditions ◽  
Green Tea Extract ◽  
Viscosity Data ◽  
Skin Protection ◽  
Multiple Emulsion ◽  
Multiple Emulsions ◽  
Tea Extract

Complex multiple emulsions have an excellent ability to fill large volumes of functional cosmetic agents. This study was aimed to encapsulate large volume of green tea in classical multiple emulsion and to compare its stability with a multiple emulsion without green tea extract. Multiple emulsions were developed using Cetyl dimethicone copolyol as lipophilic emulsifier and classic polysorbate-80 as hydrophilic emulsifier. Multiple emulsions were evaluated for various physicochemical aspects like conductivity, pH, microscopic analysis, rheology and these characteristics were followed for a period of 30 days in different storage conditions. In vitro and in vivo skin protection tests were also performed for both kinds of multiple emulsions i.e. with active (MeA) and without active (MeB). Both formulations showed comparable characteristics regarding various physicochemical characteristics in different storage conditions. Rheological analysis showed that formulations showed pseudo plastic behavior upon continuous shear stress. Results of in vitro and in vivo skin protection data have revealed that the active formulation has comparable skin protection effects to that of control formulation. It was presumed that stable multiple emulsions could be a promising choice for topical application of green tea but multiple emulsions presented in this study need improvement in the formula, concluded on the basis of pH, conductivity and apparent viscosity data.

scholarly journals The Morphology of Freeze-Dried Rubidium Chloride Powder

1989 ◽  
Vol 155 ◽  
Author(s):  
J. K. G. Panitz ◽  
J. A. Voigt ◽  
F. A. Greulich ◽  
M. J. Carr ◽  
M. O. Eatough
Keyword(s):  
Droplet Size ◽  
Freeze Drying ◽  
Low Concentrations ◽  
Aerosol Spray ◽  
Freeze Dried ◽  
Primary Particles ◽  
Ionic Compounds ◽  
Freezing Cycle ◽  
Average Size ◽  
Stock Solutions

ABSTRACTWe have formed powders of a strongly ionic compound, RbCl by freezedrying. Stock solutions, varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water to saturated solutions with 80 gm reagent in 100 cc water, were sprayed into isopentane at -160°C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to extremely small droplets in an aerosol spray. It was determined that both the concentration of the stock solution and the droplet size affect the average size and the size distribution of the primary particles formed and the way in which these primary particles are bonded together. Unlike the powders of many less ionic compounds that are produced by freeze-drying, the primary particles in these RbCl powders are crystalline rather than amorphous. Analysis with an x-ray diffractometer with a cold stage indicates that crystallization occurs during the freezing cycle rather than during the sublimation period of the freeze-drying process.

Operation of a nitrifying activated sludge airlift (NASA) reactor without biomass carrier

2000 ◽  
Vol 41 (4-5) ◽  
pp. 113-120 ◽  
Author(s):  
J.L. Campos ◽  
R. Mendez ◽  
J.M. Lema
Keyword(s):  
Activated Sludge ◽  
Air Flow ◽  
Small Diameter ◽  
Operation Time ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Total Biomass ◽  
Low Concentrations ◽  
The Mean ◽  
Very High

An ammonia loading rate of 4.1 kg N-NH4+/m3d was fully oxidized to nitrate using a nitrifying airlift without biomass carrier. The developed sludge, with a concentration of 12 gVSS/L and high density (100 gVSS/Lparticle), allowed particles to be retained with small diameter, having very low concentrations of solids in the effluent (5–10 mg VSS/L). The mean diameter of particles containing the majority of total biomass increased from 220 to 360 m during the operation time. The particle size analysis showed that the percentage of flocs with small diameter (1–3 m) is very high but the biomass content of these flocs is negligible with respect to the total biomass value. The oxygen transfer coefficient (KLa) was measured operating at different air flow rates, obtaining similar values during the overall operational period. The use of activated sludge without support gives high nitrifying rates with an easier fluidization and a lowercritical air flow rate than in a biofilm airlift reactor.

Particle and droplet size analysis from chord distributions

1999 ◽  
Vol 102 (1) ◽  
pp. 75-83 ◽  
Author(s):  
M.J.H. Simmons ◽  
P.A. Langston ◽  
A.S. Burbidge
Keyword(s):  
Droplet Size ◽  
Size Analysis

Abnormal porphyrin profile in mussels exposed to low concentrations of cadmium in an experimental Precambrian Shield lake

1995 ◽  
Vol 52 (6) ◽  
pp. 1286-1293 ◽  
Author(s):  
G. Chamberland ◽  
D. Bélanger ◽  
N. Larivière ◽  
L. Vermette ◽  
J. F. Klaverkamp ◽  
...  
Keyword(s):  
Protoporphyrin Ix ◽  
Fluorescence Analysis ◽  
Uroporphyrinogen Decarboxylase ◽  
Elliptio Complanata ◽  
Northwestern Ontario ◽  
Iron Salts ◽  
Low Concentrations ◽  
Iron Deficient ◽  
Potential Applications ◽  
Anodonta Grandis

Seven porphyrins previously suggested as biomarkers of chemical stress in mammals were identified and quantified in the freshwater mussels Elliptio complanata and Anodonta grandis grandis. Uroporphyrin, heptacarboxyporphyrin, hexacarboxyporphyrin, pentacarboxyporhyrin, coproporphyrin and protoporphyrin IX were determined using a method based on esterification of carboxylic acid moieties with BF3-methanol, extraction of the derivatives in chloroform, and HPLC–fluorescence analysis. Porphyrin profiles were compared in reference mussels sampled from nonpolluted lakes versus mussels exposed to 100 μg Cd/L in iron deficient conditions in the laboratory for 1 month or 54–177 ng Cd/L for 4–5 years in an experimental lake (northwestern Ontario, ELA, lake 382). The levels of protoporphyrin and mesoporphyrin were markedly elevated in specimens exposed to iron/salts deficiency and 100 μg Cd/L. In mussels sampled from lake 382, abnormal alterations in the relative proportions of uroporphyrin to heptacarboxyporphyrin, heptacarboxy- to meso-porphyrin, heptacarboxy- to proto-porphyrin, coproporphyrin to mesoporphyrin, and copro- to proto-porphyrin were consistent with a cadmium-mediated response. Thus, differences in the relative proportions of porphyrins, especially those associated with the accumulation of heptacarboxyporphyrin, indicate that Cd may be inhibiting uroporphyrinogen decarboxylase, suggesting potential applications of mussels' porphyrin profile as an ecotoxicological biomarker for Cd and possibly other metals.

Misting droplet size analysis in a metered film coater

2008 ◽  
Vol 86 (2) ◽  
pp. 215-218 ◽  
Author(s):  
G. Ascanio ◽  
B. Taboada ◽  
P.A. Tanguy
Keyword(s):  
Droplet Size ◽  
Size Analysis

Aggregation of zinc tetraphenylporphyrin characterized by ensemble and single-molecule fluorescence spectroscopy

2011 ◽  
Vol 89 (2) ◽  
pp. 122-129 ◽  
Author(s):  
Jaclyn A. O’Brien ◽  
Yin Lu ◽  
Emma N. Hooley ◽  
Kenneth P. Ghiggino ◽  
Ronald P. Steer ◽  
...  
Keyword(s):  
Single Molecule ◽  
Fluorescence Emission ◽  
Blue Shift ◽  
Water Soluble ◽  
Annihilation Process ◽  
Single Molecule Fluorescence ◽  
Low Concentrations ◽  
Single Molecule Fluorescence Spectroscopy ◽  
Potential Applications ◽  
Significant Blue Shift

The aggregation of metalloporphyrins is believed to play a crucial role in the excited-state annihilation process known as triplet–triplet annihilation, which in turn has significant potential applications in photon upconversion schemes. In this work, the propensity of the water-soluble metalloporphyrin zinc (II) meso-tetra(4-sulfonatophenyl)porphine to undergo aggregation when adsorbed to glass cover slips was investigated by single-molecule fluorescence microscopy. In proof-of-principle experiments, it was demonstrated (1) that individual molecules of the metalloporphyrin can be directly visualized in spite of their very weak fluorescence emission, and (2) that at low concentrations (10−8 mol/L), the molecule has a strong tendency to form multimolecular aggregates. A subset of the multimolecular aggregates shows a significant blue-shift in fluorescence emission, though at present the precise nature of the molecular aggregates remains unclear.

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