Surface Viscosity Measurements Research Articles

Fluidized spanlastics for intranasal brain delivery of lacosamide aiming to control Status Epilepticus: Design, Characterization, Ex-vivo permeation, Radioiodination and In-vivo biodistribution studies

Status Epilepticus (SE) is a neurological condition characterized by anomalous brain activity, causing repetitive seizures lasting for more than 5 min or periods of unusual behavior without returning to a normal level of consciousness between episodes. Chitosan has shown various pharmaceutical benefits, particularly in intranasal administration. In the current manuscript, novel ultra-deformable vesicles (fluidized spanlastics) loaded with lacosamide (LCM), a model anti-epileptic drug, were formulated and compared with their chitosan containing counterparts. The formed vesicles were assessed for their particle size (PS), zeta potential (ZP), entrapment efficiency (EE%) and storage stability. Surface morphology, pH and viscosity measurements, in-vitro release study and release kinetics, and ex-vivo permeation across nasal sheep mucosa were carried out on the optimized formulations. The bio-distribution and pharmacokinetic studies were performed using the radioiodinated-LCM (131I-LCM) utilizing different routes of administration to assess the in-vivo performance of intravenous solutions (IVs), intranasal solutions (INs) and the intranasal administered optimized formula (INFS). LCM-vesicles showed PS ranging from 109.90 to 418.4 nm, negative ZP values ranging from −28.00 to −48.30 mV in case of regular vesicles and shifted to +16.70 to +18.72 mV in case of chitosan coated vesicles, high EE% values having a range of 65.76–97.25 % and good storage stability properties. The optimized formulation showed spherical shape and enhanced ex-vivo permeation approximately 4-fold higher compared to LCM solution. The results of the in-vivo study demonstrated that the brain/blood ratio (B/B) of INs was 3.3-fold higher than IVs and INs of 131I-LCM in the first 5 min. Accordingly, the prepared system has been shown to possess a promising potential for brain diagnosis and/or therapy.

Development and characterization of lanolin incorporated electrospun nanofibers for nursing pads

In this study, to combine the biological properties of lanolin and the advantages of electrospun nanofiber mats for developing a potent topical wound dressing/nursing pads that includes lanolin, lanolin incorporated electrospun cellulose acetate (CA), polyethylene oxide (PEO), polyethylene oxide/chitosan (PEO/chitosan) and thermoplastic polyurethane (TPU) nanofibers were developed and characterized. Surface tension, viscosity and conductivity measurements of each polymer solution were carried out in order to characterize the spinning solutions. Lanolin addition did not affect the conductivity values but increase the viscosity of each spinning solution. According to the SEM images, smooth nanofiber surfaces were produced which could be appropriate for a top layer of a nursing pad. Slightly attached, thicker nanofibers could be seen from the TPU/Lanolin images. Similar to TPU nanofibers, CA nanofibers were smoother and thinner than CA/Lanolin nanofibers. Lanolin effected the uniformity of the PEO nanofibers, but it could be said that homogeneous distribution of lanolin was achieved. Characterization of these nanofiber membranes were also carried out with FTIR, DSC, swelling and weight loss analysis. Since TPU nanofibers were hydrophobic and the addition of lanolin made the nanofiber more hydrophobic, they did not show high swelling ratios. CA nanofibers swelled 610% due to their relatively hydrophilic nature and bulky structure. PEO nanofibers were totally dissolved in the water, a very thin layer remained for PEO-Chitosan/lanolin nanofibers. So, using electrospun CA and TPU nanofiber membranes for a nursing pad upper layer could be suitable. CA/lanolin nanofibers showed better hydrophilicity and swelling when compared to TPU nanofibers. On the other hand, TPU nanofibers are more elastic and durable with lower swelling.

Density, viscosity and surface tension of high-silicate CaO–SiO2 and CaO–SiO2–Fe2O3 slags derived by aerodynamic levitation. The behavior of Fe3+ in high-silicate melts

Thermophysical data for liquid slag are required for the optimization and control of metallurgical processes. The density, surface tension and viscosity were measured by employing aerodynamic levitation under contactless conditions. The high-silicate slag (44 and 63 mass-% of SiO2) of the CaO–SiO2 and CaO–SiO2–Fe2O3 systems (with 5 and 10 mass-% Fe2O3) was investigated under (80% Ar + 20% O2) gas atmosphere. The temperature ranges were between 800 °C and 2000 °C for the density and 1500 °C–2000 °C for surface tension and viscosity measurements. The influence of the CaO/SiO2 ratio on the investigated properties and the behavior of Fe3+ ions in high-silicate melts were examined. The density of the CaO–SiO2 melt was lower than that of the CaO–SiO2–Fe2O3 systems. The surface tension of all compositions tested decreased with temperature and showed compositional dependence. The viscosity measured was higher in the Fe2O3-containing slag. The Raman spectroscopy analyses confirmed the increase in the degree of polymerization with the addition of Fe2O3 for the silicate-rich slag. The formation of a complex anion of a ferric ion and contribution to the silicate network were assumed. The trends observed were related to the structural properties and different interionic bonding. Urbain's viscosity model and FactSage™ 7.3 were applied for the assessment of the experimental data.

Improvement of the durability of cement-based material through surface modification with nano-engineered releasing agents

• Modified releasing agent with NS/NT to make nano-engineered releasing agent. • NS and NT increased the contact angle of releasing agent and help their adhesion on mold. • Reduction of the surface porosity (within 2 mm thick). • Nano-engineered releasing agent can achieve durable concrete surface. Aggressive substances can gain access to the inner structure of cement-based materials through the surface, resulting in deterioration of the structure. This work developed an effective way of improving the quality of cement-based materials surface by applying nanoSiO 2 -/nanoTiO 2 -engineered releasing agents (nSRa/nTRa) on the formwork surface. Continued with our previous work, the positive effects of nSRa/nTRa on cement hydration were used to improve the surface quality of the cement-based samples through its spraying on the mold surface. This work firstly characterized the adhesive properties of these agents on mold surface (contact angle and viscosity measurement), and then their effects on the surface microstructure and the durability of cement-based materials such as 1) sulfate resistance, 2) chloride resistance, and 3) freeze–thaw resistance were determined. Results showed that nanoparticle addition increased the contact angle of releasing agents and helped their adhesion to mold. Applying nSRa/nTRa on cement-based samples benefited the reduction of surface porosity (within 2 mm thick) by 14.2 %, 19.4 %, 8.6 %, and 18.9 % in the nS2Ra-, nS4Ra-, nT4Ra- and nT16Ra-engineered samples. After 120 days of sulfate attack, mortar samples cast in Ra-, nS4Ra-, and nT16Ra-coated molds showed reductions in compressive strength loss of 1.57 %, 0.73 %, and 0.23 %. Noticeable reductions in the chloride migration coefficient of 23.9 % and 26.6 % were found in the nS4Ra-/nT16Ra-modified mortar sample, while their relative dynamic modulus elasticity was 6.72 % and 12 % higher than Ra-sample after 200 freeze–thaw cycles. This work proved that nano-engineered releasing agents can effectively improve the durability of the concrete structure.

Status of the Electrostatic Levitation Furnace in the ISS -Surface Tension and Viscosity Measurements

Status of the Electrostatic Levitation Furnace in the ISS -Surface Tension and Viscosity Measurements

Anticancer Activity of 5-Fluorouracil-Loaded Nanoemulsions Containing Fe3O4/Au Core-Shell Nanoparticles

Nanoemulsions (NEs) as multi-compartmentalized systems are extensively considered as versatile drug delivery systems, due to their multifunctional and tuneable physicochemical properties. Here, water-in-oil-in-water (WOW) NEs were formulated using Juglans regia-based Fe3O4/Au-core-shell nanoparticles to encapsulate 5-Fluorouracil (5-FU) for potential colorectal cancer treatment. Response surface methodology, FTIR, TGA, TEM, DLS, VSM, UV-vis spectroscopy, and viscosity measurements were used to characterize the fabricated samples. The analysis confirmed the successful synthesis of Au, Fe3O4, and Fe3O4/Au core-shell nanoparticles with the Juglans regia (J. regia) extract as a green stabilizer and also reducing agent. The NE displayed a spherical-shape and TEM size of~30 nm. It also exhibited good colloidal stability and multifunctional features related to its components. TGA data indicated that 5-FU increased thermal stability after its loading into the nanoemulsion as a drug carrier. 5-FU release from the NE carrier presented a time-delayed behavior and higher release dosage in media at pH 4 compared to pH 7 within 48 h. When tested against colorectal-derived cell lines, 0.78 µg/mL of 5-FU-loaded Fe3O4/Au core-shell NEs showed potent anticancer activity against HCT116 cancerous cells, while exhibiting low toxicity towards CCD112 normal cells. In conclusion, the synthesized 5-FU-loaded NEs can be potently used as an anticancer drug carrier model, owing to its nano-scale size and other functionalities, which should be further studied.

Simultaneous measurement of surface tension and viscosity of oscillating droplet using time-resolved rainbow refractometry

Oscillation of micron-sized liquid droplet is an interesting and common phenomenon, and is used to measure surface tension and viscosity with the recently developed time-resolved rainbow refractometry. Droplets produced by a monodisperse droplet generator are excited to oscillate at a small amplitude (less than 1%) and high frequency (of the order of 10 kHz) by applying a periodic tiny disturbance. The aspect ratio of a spheroidal droplet is quantified by time-resolved angular shift of rainbow signal. Thus the droplet shape oscillation is quantified by its unsphericity, instead of calculated from the polar radius or the variation of surface area. Experiments on several liquids were conducted to evaluate the validation of the experimental system. The results present that the relative errors of measured values of the surface tension and viscosity are less than 5% and 10%, respectively, promising the great potential of rainbow refractometry for liquid surface properties measurement.

Metformin-Loaded Polymer-Based Microbubbles/Nanoparticles Generated for the Treatment of Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease that is increasingly common all over the world with a high risk of progressive hyperglycemia and high microvascular and macrovascular complications. The currently used drugs in the treatment of T2DM have insufficient glucose control and can carry detrimental side effects. Several drug delivery systems have been investigated to decrease the side effects and frequency of dosage, and also to increase the effect of oral antidiabetic drugs. In recent years, the use of microbubbles in biomedical applications has greatly increased, and research into microactive carrier bubbles continues to generate more and more clinical interest. In this study, various monodisperse polymer nanoparticles at different concentrations were produced by bursting microbubbles generated using a T-junction microfluidic device. Morphological analysis by scanning electron microscopy, molecular interactions between the components by FTIR, drug release by UV spectroscopy, and physical analysis such as surface tension and viscosity measurement were carried out for the particles generated and solutions used. The microbubbles and nanoparticles had a smooth outer surface. When the microbubbles/nanoparticles were compared, it was observed that they were optimized with 0.3 wt % poly(vinyl alcohol) (PVA) solution, 40 kPa pressure, and a 110 μL/min flow rate, thus the diameters of the bubbles and particles were 100 ± 10 μm and 70 ± 5 nm, respectively. Metformin was successfully loaded into the nanoparticles in these optimized concentrations and characteristics, and no drug crystals and clusters were seen on the surface. Metformin was released in a controlled manner at pH 1.2 for 60 min and at pH 7.4 for 240 min. The process and structures generated offer great potential for the treatment of T2DM.

Foaming behavior of fluorocarbon surfactant used in fire-fighting: The importance of viscosity and self-assembly structure

In this work, we systematically investigated the foaming behavior of a zwitterionic fluorocarbon surfactant (FC1157) used in fire-fighting. Two different foaming methods were used to generate foam, and the foaming behaviors of the fluorocarbon surfactant and typical hydrocarbon surfactants were compared. Multiscale approaches including cryogenic-transmission electron microscopy (cryo-TEM), surface tension measurements, viscosity and turbidity measurements were employed. Our results revealed that the foaming behavior of FC1157 is different from that of the hydrocarbon surfactants, which is not only related to the surfactant adsorption dynamics but also to the solution viscosity. We confirmed that the increased viscosity leads to a decrease in foaming ability and FC1157 is the only surfactant which exhibits viscous behavior in solution. The viscosity change is due to the variation in solution turbidity which comes from the formation of large aggregates in bulk. Cryo-TEM experiments indicated that FC1157 molecules tend to self-assemble in solution into vesicles. The presence of the vesicle phase strongly affects the solution viscosity and thus the foaming ability, which is different from that observed in the systems containing hydrocarbon surfactants. This study provided insight into the basic factors affecting the foaming behavior of the fluorocarbon surfactant used in fire-fighting, highlighting the crucial role of viscosity and self-assembly structure in determining the foaming behavior.

Audible Sound from Vibrating Sessile Droplets for Monitoring Chemicals and Reactions in Liquid.

To reduce environmental impact and sensor footprint, researchers need cost-effective and small-size surface tension and viscosity measurement devices. New measurement principles are needed for such sensors. We demonstrate that a sessile droplet's mechanical vibration can be transformed to audible sound, by recording the ultrasonic Doppler frequency shift in the form of an acoustic signal. The recorded sound wave reveals a droplet's surface tension and its viscosity, through its frequency spectrum and attenuation rate of the signal, respectively. Based on such sensors, two chemical measurements inside sessile droplets are shown: (I) titration of a Ni2+ and Co2+ mixture with a surface-active indicator (using surface tension) and (II) measurement of the molecular weight of a polymer in solution (using viscosity). Unlike the commercial technique, our ultrasound-based sensor is cost-effective in terms of equipment price and sample volume.

A small-volume, high-throughput approach for surface tension and viscosity measurements of liquid fuels

An ongoing effort looking at bioblendstocks to function as drop-in replacements or blending components for gasoline has identified a large number of candidate fuels. This work documents an approach for rapid screening of candidate fuels using relatively small sample sizes () that targets two key physical properties of liquid fuels—surface tension and viscosity. The approach utilizes shape oscillation dynamics of single droplets generated by a piezo-electric device and their decay over time. Strobed imaging of the oscillation process is used along with image processing, edge detection, and data analysis to capture the decay of the oscillation over time. The time constant of the decay process along with oscillation frequency are then used to estimate viscosity and surface tension using a theory for small amplitude droplet oscillations. Measurements are obtained for primary reference fuels (isooctane and n-heptane) as well as candidate fuels from four bio-derived functional groups of interest. Measurement results for surface tension and viscosity are correlated with literature data as well as measurements from standard reference instruments. The measurement results show that the droplet oscillation based approach is capable of reproducing surface tension and viscosity values for the tested fuels within deviations of 7% and 13% respectively from literature data. Results are obtained using an average of 5 µl per fuel within about 20 s, thus demonstrating a small-volume, high-throughput approach that can be used for screening of candidate bioblendstock fuels.

New class of cocogem surfactants based on hexamethylenediamine, propylene oxide, and long chain carboxylic acids: Theory and application

Six cocogem surfactants were synthesized from N,N,Nʹ,Nʹ-tetra-(propane-2-olyl)-1,6-hexanediamine and higher monocarboxylic acids: capric, lauric, myristic, palmitic, stearic and oleic. N,N,Nʹ,Nʹ-tetra-(propane-2-olyl)-1,6-hexanediamine was synthesized from hexamethylenediamine and propylene oxide at room temperature, without utilizing any catalyst or solvent. Surface tension, conductivity, foaming ability, foam stability, emulsion stability, viscosity and density measurements were performed on aqueous solutions of all cocogem surfactants. Their surface activity and colloidal-chemical parameters such as critical micelle concentration (CMC), surface pressure at CMC (πCMC), surface tension at CMC (γCMC), surface excess (Γmax), concentration required for 20mN/m reduction of surface tension (C20), Gibbs energies of adsorption and micellization (ΔGad and ΔGmic) were recorded and variation of these parameters based on hydrophobic chain length and structure was investigated experimentally and computationally. Synthesized surfactants with myristic, palmitic, and stearic tail continued to decrease surface tension even above CMC. The possible reason of this unusual behavior was determined based on computational studies. Surface activity parameters of cocogem surfactant with oleic tail disobeyed the general tendency established by other cocogems with saturated tail group. Palmitic and stearic acid based cocogem surfactants had good foam stability and the reason of this high foam stability was rationalized with high viscosity of their solutions.

Экспериментальное исследование поверхностного натяжения ферроколлоида в магнитном поле

Direct measurements of surface tension, viscosity and surface elasticity under the action of external forces are often impossible. In many tasks, the magnetic fluid surface tension is considered to be independent of the magnitude of the applied magnetic field and is determined by the properties of the base fluid. The anisotropy of the magnetic properties at the interface due to the jump in the fluid’s magnetization suggests the dependence of the surface tension tensor on the magnetic field. In this paper, we propose a new experimental method for studying the surface tension of a magnetic fluid in an external uniform magnetic field, depending on the orientation of the magnetic field intensity towards the liquid-gas interface. The study was carried out with the help of modified capillary wave method in a magnetic field orthogonal to the liquid surface and with the ring detachment method in the case of a longitudinal field. It was shown experimentally that the surface tension of a ferrocolloid fluid base (kerosene) does not depend either on the frequency of capillary waves excitation or on intensity of an applied external magnetic field, and corresponds to the value determined with the help of a commercial tensiometer by the standard method of ring detachment. The surface tension of the ferrofluid decreases with increasing intensity of the orthogonal magnetic field interface and with increasing frequency of acoustic vibrations. However, an increase in the field strength longitudinally directed to the interface, provokes an increase in the surface tension of the magnetic fluid. The experimental results are in qualitative agreement with theoretical predictions by A. V. Zhukov: the eigenvalues of the surface tension tensor monotonically increase with the tangential magnetic field component and monotonically decrease with an increase in its normal component.

Thermophysical Properties of Advanced Ni‐Based Superalloys in the Liquid State Measured on Board the International Space Station

Advanced nickel‐based superalloys combine excellent high‐temperature mechanical strength, creep resistance, and toughness, and therefore find applications in next‐generation aircraft engines and turbines for land‐based power generators. The related fabrication processes are complex, time consuming, and costly, making it necessary to perform supporting computer simulations of the heat and material flow in the melt before and during crystallization. Such models are based on reliable thermophysical property data in the solid and liquid phase. However, measurements of surface‐ and volume‐dependent properties, such as liquid surface tension, viscosity, and specific heat of these complex liquid metal alloys, are very challenging, due to the melts high chemical reactivity at temperatures of interest. The method of choice is electromagnetic levitation, a containerless method. The measurements of surface tension, viscosity, mass density, and specific heat capacity, performed in the electromagnetic levitator (EML) on board the Space Laboratory Columbus in the International Space Station (ISS), are presented and discussed.

Interactions between fluorocarbon surfactants and polysaccharides

Interactions between the mixtures of fluorine surfactants (FS) of different chemical character (anionic - Capstone FS-64, cationic - S-106A and non-ionic - Capstone FS-30) and polysaccharides (anionic – carboxymethyl cellulose (CMC), cationic starch (CS) and non-ionic – hydroxyethyl cellulose (HEC)) have been investigated by surface tension, viscosity and nuclear magnetic resonance (NMR). The factors governing the formation of polysaccharide-surfactant complexes (PSC) were discussed in terms of the electrostatic and hydrophobic interactions. The surface tension and viscosity measurements allow to find out in which systems the interactions occur and also when they start and end. NMR was studied not only to analyse the chemical structures of the fluorine surfactants but also to determine the characteristics of PSC.

Surface tension and viscosity of liquid Pd43Cu27Ni10P20 measured in a levitation device under microgravity

Here we present measurements of surface tension and viscosity of the bulk glass-forming alloy Pd43Cu27Ni10P20 performed during containerless processing under reduced gravity. We applied the oscillating drop method in an electromagnetic levitation facility on board of parabolic flights. The measured viscosity exhibits a pronounced temperature dependence following an Arrhenius law over a temperature range from 1100 K to 1450 K. Together with literature values of viscosity at lower temperatures, the viscosity of Pd43Cu27Ni10P20 can be well described by a free volume model. X-ray diffraction analysis on the material retrieved after the parabolic flights confirm the glassy nature after vitrification of the bulk samples and thus the absence of crystallization during processing over a wide temperature range.

Interaction of Bile Salts with Cetylpyridinium Chloride: Surface Tension and Viscosity Measurements

Background: Bile salts possess unique chemical structural characteristics and are very different from conventional surfactants. Due to the fascinating physiological functions, the bile salts have been widely studied by various physical methods. Last three decades are the witness about rapid studies on bile salts aggregation with surfactant but yet uncertain related to mixed micellar system. Objective: The primary objective of this study was to undertake systematic studies on the mixed systems comprising of cationic surfactant CPyCl + bile salts in water and NaCl solution by surface tension and viscosity method. Methods: Drop weight method (surface tension method) and viscometry methods are chosen to discuss the interaction between bile salts and surfactant mixed system. Results: Systematic studies on CPyCl + bile salts were carried out using Rubingh’s regular solution theory in presence/absence of NaCl. The CMC and viscosity data measurements were recorded. Molecular interaction parameters β was calculated to determine the depth of synergism between the micellar systems. Conclusions: Synergisms occur when cationic surfactant CPyCl and bile salts such as NaDC/NaC were mixed. NaCl has the ability to modify the structure of CPyCl and bile salts. Micelle size grows with increase in NaCl concentration. CMC of CPyCl decreases as the concentration of salts increases. Viscosity data reveals that size of CPyCl micelle increases with increasing NaCl concentration. Keywords: Bile salt, micellization, surfactant, CMC, hydrographic, aliphatic.

Enhanced foamability and foam stability of polyoxyethylene cholesteryl ether in occurrence of ionic surfactants

The micellization and foam studies of binary surfactant mixtures assembled of nonionic polyoxyethylene cholesteryl ether (ChEOn; where n = 30), cationic hexadecyltrimethylammonium bromide (CTAB) and anionic sodium dodecylbenzenesulfonate (SDBS) was investigated by surface tension, foaming behavior and viscosity measurements. As an exceptional outcome it was observed that foam stability and foamability of nonionic surfactant ChEO30 in mixtures with ionic surfactants is much superior to the individual ChEO30, CTAB or SDBS components. Moreover, the mixed surfactant systems (ChEO30+CTAB) and (ChEO30+SDBS) have much lower critical micellar concentrations (CMCs) than corresponding sole surfactants. The negative values of interaction parameter (β) estimated from Rubingh’s theory specify synergism amongst mixed ChEO30+CTAB and ChEO30+SDBS surfactants systems.

Simultaneous measurement of surface tension and viscosity using freely decaying oscillations of acoustically levitated droplets

Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.

Colloid properties of hydrophobic modified alginate: Surface tension, ζ-potential, viscosity and emulsification

Micelle properties of hydrophobic modified alginate (HM-alginate) in various dispersion media have been studied by surface tension, ζ-potential, and viscosity measurements. Effect of salt on micelle properties showed that the presence of counter ion weakened the repulsive interaction between surfactant ions, decreased the critical micelle concentration (CMC) value of the HM-alginate, reduced the effective volume dimensions of HM-alginate and hence viscosity, which coincide with the corresponding ζ-potential values. Soy oil-in-water emulsions, stabilized solely by HM-alginate, were produced in high speed homogenization conditions and their stability properties were studied by visual inspection, optical microscopy and droplet size measurements. The results showed that emulsions (oil-water ratio was 1:7) containing 15mg/mL HM-alginate presented better stability during 15days storage, which stating clearly that HM-alginate is an effective emulsifier to stabilize oil-in-water emulsions. The herein presented homogeneous method for preparation of emulsion has the potential to be used in food industry.