Aqueous Solution Of Carboxymethyl Cellulose Research Articles

Examining the interfacial behavior of non-Newtonian gas-liquid two-phase flow in horizontal square microchannels

This study investigates the flow dynamics of a non-Newtonian two-phase flow within a horizontal square microchannel. The experimental apparatus employed an acrylic channel with a side length of 8 × 10−4 m. Nitrogen served as the test gas, and the test liquids consisted of water and CMC (Carboxymethylcellulose) aqueous solutions at concentrations of 0.2 and 0.4 %wt. The superficial velocity of working gas and liquids spanned ranges of 0.26–20 m/s and 0.05–1.0 m/s, respectively. A differential pressure transducer was used to measure pressure gradients, while a high-speed video camera captured the flow behavior for analysis with a custom image processing technique. Nonlinear regression statistical analysis was applied to establish the criteria for flow pattern transition. Furthermore, signal processing techniques such as PSD (Power Spectral Density), DWT (Discrete Wavelet Transform), ANN (Artificial Neural Network), and Kolmogorov entropy were employed to analyze the flow behavior based on the pressure gradient signals from the differential pressure transducers. Our findings reveal the occurrence of bubbly, slug, slug-annular, and churn flow patterns. The nonlinear regression statistical analysis offered ambiguous results for determining flow pattern transitions. However, an empirical coefficient was obtained for the nondimensional liquid height. Moreover, the empirical nondimensional liquid height aligned well with the experimental values. The PSD and DWT analysis corroborated each other in clearly characterizing the flow pattern based on pressure gradient fluctuation and wavelet energy. The Kolmogorov entropy effectively captured the chaotic flow pattern. Furthermore, the ANN analysis demonstrated a solid agreement between the predicted and actual flow patterns.

Chitosan and sodium carboxymethylcellulose biocomplex interaction properties for biomedical and pharmaceutical applications

ABSTRACT The naturally occurring polymers chitosan (CH) and sodium carboxymethylcellulose (CMC) have attracted the interest of researchers in a variety of biomedical and pharmaceutical applications such as drug delivery, cosmetics, and tissue engineering. However, CMC and CH have certain limitations for use in controlled aqueous CMC/CH mixed solutions. In this study, aqueous solutions of CMC and CH with the same concentration of 0.5 g/l and pH 6 are mixed under atmospheric conditions. The effects of temperature and molar volume fraction X1 of CMC on the decreased electrical conductivity of CMC/CH mixed solutions were studied at different temperatures ranging from 15°C to 80°C. We highlighted that different regions can be distinguished in the aqueous CMC/CH complexes, depending on the composition and electrostatic interactions of the solutions, which are associated with significantly different phase behaviors.

Hydrodynamics of a bubble passing through a Kelvin cell in microchannel with shear-thinning fluid

Open cell solid foams (OCSF) show great potential for process intensification in heterogeneously catalyzed reactions due to their favorable properties regarding heat-mass transfer, pressure drop and specific surface area (SSA). As one of the most ideal OCSF structure, Kelvin cell (KC) exhibits a fundamental importance in fully understanding the complex flow and transport properties of these reactions, but the research involving gas-liquid two-phase flow is still missing. In this work, the hydrodynamics of a bubble through a representative elementary volume with KC model in minichannel with sodium carboxymethyl cellulose aqueous solution are investigated by coupled level-set and volume-of-fluid method. The regime of bubble penetration into KC is elucidated. The specific surface area and permeability of bubble are studied by systematically analyzing the influences of solution concentration, liquid velocity, KC's porosity and contact angle, as well as fluid type. Four penetration regimes of approaching stage, engraving stage, extruding stage, and deviating stage are identified, and a typical curve of SSA of bubble in terms of flow time is acquired accurately. It is found that the drastic changes in SSA and permeability are closely related to the engraving and extruding stages. The average SSA in two involved stages increases with solution concentration, decreases with KC's porosity. The maximum permeability corresponding to the transition point between two stages, decreases with solution concentration, increases slightly with KC's porosity. However, liquid flow velocity and KC's contact angle have no significant effect on both the average SSA and the maximum permeability. Compared with water, a small SSA tends to be obtained and the permeability climbs slowly but reaches a high peak in CMC solution.

Assessment of the preventive activity of Pinus brutia Ten. (Pinaceae) against in vivo acute lung injury model

Acute lung injury is a crucial inflammation-induced lung complication. Acute respiratory distress syndrome, which has a more severe course and is characterized by diffuse infiltration, develops with the progression of acute lung injury. The incidence of acute lung injury and acute respiratory distress syndrome is high and are both associated with increased mortality and morbidity rates worldwide. The leaves (needles) of Pinus brutia Ten. (Pinaceae) have been traditionally used against bronchitis and asthma. In addition, there are many Turkish folk medicine records regarding the use of its cones in respiratory system diseases such as cough, hoarseness, lung diseases, bronchitis, asthma, tuberculosis, and pneumonia. The present study aims to comparatively investigate the in vivo biological activity of the needles and cones of P. brutia against Acute Lung Injury (ALI) and to evaluate its potential use. The extracts of P. brutia needles and cones were investigated in ALI model in rats. Male Sprague Dawley rats were divided into sham control, lipopolysaccharide (LPS), reference, and six treatment groups. ALI model was induced by intraperitoneal (i.p.) LPS (5 mg/kg) injection. One hour before LPS administration, needle and cone extracts of the P. brutia at doses of 100, 200, and 400 mg/kg were given to the treatment groups. Carboxymethyl cellulose aqueous solution (0.5%) was given to the sham control group and LPS group. Dexamethasone (1.5 mg/kg) was administered to the reference group. In the 4th hour after LPS administration, inflammatory cells were counted in bronchoalveolar lavage fluid (BALF), and the levels of interleukin (IL)− 6 and − 8, and tumor necrosis factor-alpha (TNF-α) were measured by enzyme-linked immunosorbent assay (ELISA). Oxidative stress index (OSI) values and peroxiredoxin (PRDX)− 1 gene expression in lung tissues were calculated by quantitative real time polymer chain reaction (RT-PCR). Histopathological examination was performed by Hematoxylin Eosin (HE) and Masson Trichrome (MT) staining methods. In addition, the amounts of the phenolic compounds were determined by High Performance Liquid Chromatography (HPLC). Catechin hydrate and vanillic acid were determined to be higher; taxifolin was lesser in the cone extract than the needle extract. The best improvement in the macroscopic appearance of the lungs was observed in the cone extract (200 mg/kg) group compared to the other treatment groups. While the percentage of inflammatory cells in BALF was increased in the LPS group, these cells were in the lowest rate in the cone extract (200 mg/kg) group. Both needle and cone extracts decreased the levels of inflammatory cytokines. The OSI values in the treatment groups decreased compared to the LPS group. PRDX-1 levels were the highest in the LPS group, but this level dropped in the treatment groups. The inflammation of the lung tissue in the LPS group was higher than in the other groups. The recovery of inflammation was similar to both needle and cone extracts of P. brutia. These data provide evidence that 200 mg/kg of the cone extract is a potential candidate for the prevention of ALI and warrants further preclinical evaluation.

Global characterization of hydrodynamics and gas-liquid mass transfer in a thin-gap bubble column in presence of Newtonian or non-Newtonian liquid phase

Bubble columns are commonly used as photobioreactors (PBRs) due to their good mixing and mass transfer capabilities. Modification in design and operating parameters are nevertheless needed to intensify volumetric productivity. Thin-gap bubble column can be used in this context to operate with high biomass concentration, up to conditions where the culture becomes non-Newtonian. In the present study, the global hydrodynamics and gas–liquid mass transfer inside a 4 mm thickness thin-gap bubble column are characterized in presence of low viscosity Newtonian fluid (water) and two aqueous solutions of Carboxymethyl Cellulose and Xanthan Gum. These shear-thinning solutions are used to mimic high concentration cultures of Chlorella Vulgaris at 42 g.L−1. A range of superficial gas velocities and different capillary diameters are explored to investigate the effect of sparging on hydrodynamics and gas–liquid mass transfer. Studied parameters are flow regimes, mixing, and gas–liquid mass transfer. Results are compared with literature results in classical bubble columns to put into evidence the original effects of both confinement and liquid rheology. Among others, these results show that compared to Newtonian media, non-Newtonian media result in higher gas holdup and mixing times and a lower gas–liquid mass transfer coefficient. The findings suggest that the presence of smaller bubbles would improve mass transfer due to the increased interfacial area, while the presence of larger bubbles would improve mixing performance due to increased vorticity in their wake and relatively greater species transport.

Dynamic wetting of Newtonian and viscoelastic fluids on microstructured surfaces

HypothesisAlthough extensive research has been conducted on the dynamic wetting of Newtonian fluids, limited insights have been gained for viscoelastic fluids, particularly on engineered surfaces. We hypothesize that differences in dynamic wetting on microstructured surfaces exist between such fluids, which may be attributed to variations in viscosity and elasticity as well as changes in the microscopic morphology of the moving contact line.ExperimentsTo systematically investigate the wetting differences between Newtonian and viscoelastic fluids on microstructured surfaces, we conducted forced wetting experiments of glycerol-water and carboxymethyl cellulose aqueous solutions on microstructured polytetrafluoroethylene surfaces through a modified Wilhelmy plate method.FindingsResults demonstrated an apparent difference in the relationship between the dynamic contact angle and moving velocity with different microstructured surfaces for Newtonian and viscoelastic fluids. The power-law exponent between the capillary number and cubic of the dynamic contact angle increases with the strengthening of shear thinning and elastic effects. In contrast, this exponent is rarely influenced by the scale of microstructured surfaces, particularly in highly viscous regions where viscous force dominates. In addition, viscosity affects the viscous bending and distance that liquid molecules jump at the contact line. These findings have potential applications in coating complex fluids on engineered surfaces.

Irreversibility analysis of hydromagnetic viscoelastic Ag-Al2O3/water hybrid nanofluid over a stretching sheet

In many practical applications, magnetic field is applied in modulating underlying flow over a stretching sheet. In the present study, effort has been taken to analyse thermodynamic irreversibility associated with the magnetically actuated flow of viscoelastic fluid over a stretching sheet. The viscoelastic fluid chosen here constitutes aqueous solution of carboxymethyl cellulose containing modest concentration (0.0–0.4%) of Al2O3-Ag nanoparticle. For the description of flow field and thermal transport of energy, the transport equations are solved numerically. Obtained results, primarily focused on parametric variation, are portrayed graphically for different cases pertaining to this analysis. As seen, increasing the magnitude of viscoelastic parameter (K), and Hartmann number (Ha), has significant impact on the flow velocity, convective transport of heat, and consequently, on the thermodynamic irreversibility of the system. Albeit the presence of nanoparticles seems to decrease the flow velocity by yielding more drag to the underlying flow, the same effect on the velocity is found to be insignificant in this analysis, attributed primarily to the accumulation of the nanoparticles in the working fluid.

Pharmacological Effects of a New Indolinone Derivative in Experimental Pneumonitis in Rats.

We studied the effect of a new indolinone derivative GRS on animal survival and on functioning and histological structure of the lungs in rats with experimental pneumonitis. The rats of experimental groups were intratracheally administered 0.5% aqueous solution of carrageenan under intramuscular anesthesia. Compound GRS (10 mg/kg; a suspension in 0.5% aqueous solution of carboxymethyl cellulose) was orally administered for 4 days starting from the day of carrageenan administration; another rat group received the aqueous solution of carboxymethyl cellulose alone. Control rats received intratracheally isotonic solution of sodium chloride. Animal mortality was registered over 5 days; on day 5, the respiratory parameters were measured, the lungs were weighed, pulmonary edema was evaluated, and histological structure of the lungs was studied. GRS compound improved survival of animals with modeled pneumonitis, restored the respiratory parameters to the level of control animals, and reduced pulmonary edema by 35% and the severity of histological damage score in the lungs by 17% (p<0.05).

Generation of droplets of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels

The study of shear-thinning non-Newtonian fluids in T-junction parallelized microchannels provides valuable insights into the emulsification process and droplet generation synchronicity. Silicone oil is used as the continuous phase, and sodium carboxymethyl cellulose (CMC) aqueous solutions are used as the dispersed phase. Based on the evolution of the dispersed phase head and neck characteristic size, the droplet generation is classified into four stages: the waiting stage, filling stage, necking stage, and pinch-off stage. The effects of the two-phase flow rates and rheological characteristics of shear-thinning fluids on the four stages are investigated. Additionally, the coupling of interface evolution between parallelized microchannels is studied, revealing periodic changes between synchronous and asynchronous droplet generation types. The impact of this phenomenon on droplet monodispersity is analyzed, providing crucial information for the preparation of uniform droplets.

Viscous flow through a thin‐walled elastic hollow ellipsoid—Experiments to demonstrate a potential flowmeter

AbstractLarge deformation of an elastic hollow ellipsoid may be used as the mechanism of a flowmeter. It is seen as being inspired by human biology, when passing through fluid internally. The investigation on this potential was carried out where simply the relationships among pressure drop across an ellipsoid, deformation, flowrate and fluid viscosity were obtained. The elastic hollow ellipsoid was made from Silicone, which has a long axis of 0.05 m, a short axis of 0.03 m, and a wall thickness of 3.5 × 10−4 ± 4.6 × 10−5 m. A monotonic relationship between fluid flowrate and a representative diameter of the ellipsoid was found. Sodium carboxymethyl cellulose (CMC) aqueous solutions were used as a more viscous media so the effect of viscosity was explored. Unlike the firm result on flowrate gauging, it was inconclusive on differentiating the effect of viscosity. When the inlet and the outlet of the fluid were switched over, the geometrical expansion of the ellipsoid was found to be sensitive to the small spatial variation of wall thickness (a non‐uniformity caused by manufacturing limitation). Nevertheless, this work has demonstrated an interesting flowmeter and further explorations on viscosity effect may be warranted.

Polyelectrolyte complex composite cryogels with self-antibacterial properties and wide window for simultaneous removal of multiple contaminants

Tricomponent polyelectrolyte complex (PEC) composite cryogels, with remarkable sorption capacity of multiple contaminants and self-antibacterial properties were fabricated from chitosan (CS) and aromatic ionene type polycations evenly dispersed in carboxymethyl cellulose (CMC) aqueous solution. Fast cryostructuration at −196 °C (5 min) and overnight at −18 °C conducted to pre-PECs which, after exposure to a source of H+ and freeze-drying, led to PEC composite sponges. The PECs were characterized by FTIR, SEM, EDX, streaming potential titrations, swelling kinetics, swelling at equilibrium as a function of pH, and compressive tests. These PECs were able to simultaneous adsorb oxyanions (HCrO4−, H2PO4−, HAsO42−), and heavy metal ions (HMIs) (Cu2+, Cd2+, Pb2+), and to kill ∼100 % of Gram+ (Staphylococcus aureus) bacteria. Only the tricomponent PECs were able to kill 100 % of Gram- (Escherichia coli) bacteria, while the bicomponent PECs (containing only CS and CMC) were less efficient in this case (only 70 % inhibition of bacteria). The pseudo-first-order kinetic model fitted the best the kinetic data, suggesting the sorption of pollutants by physisorption. In multicomponent systems, HCrO4− ions are preferred, the selectivity coefficients being higher in the case of tricomponent PECs than in the case of bicomponent PECs, while in the case HMIs, Pb2+ ions were preferentially selected. The sustainability of the PEC composite cryogels was demonstrated by their reuse up to five sorption/desorption cycles, with a decrease of the sorption capacity in the fifth cycle of 7 % for H2PO4−, 8.1 % for HCrO4−, and 6.9 % for HAsO42− when tricomponent PEC cryobeads were used as sorbents. All these abilities recommend the PEC composite cryogels as potential materials for filters suitable for point-of-use water purification.

Assembly of electric double-layer capacitors with hardwood kraft lignin-based electrodes and separator together with ionic liquid electrolyte

Abstract This study aimed to assemble a high-performance electric double-layer capacitor (EDLC) using a hardwood kraft lignin (HKL)-based separator and HKL-based electrodes, which were fabricated from a nonwoven mat of electrospun HKL fibers. The separator was prepared by the thermostabilization of the mat derived from a mixed dope of HKL, hexamethylenetetramine, and polyethylene glycol (1.66/0.50/0.09, w/w) for electrospinning. Although a mat-type HKL-based electrode containing conductive carbon black (CB) has been reported to be suitable for a commercial cellulosic separator, this electrode was found to be unsuitable for the HKL-based separator because of its rough surface and poor contact with the separator interface. Hence, a powder-type electrode with a smooth surface was fabricated by grinding the mat, followed by casting with a carboxymethyl cellulose aqueous solution, and its EDLC possessed high energy (49 Wh kg−1) and power densities (151 kW kg−1). Moreover, to provide a simple process for electrode fabrication, another mat-type electrode was fabricated by adding CB to the mixed dope, followed by electrospinning, carbonization, and steam activation. The resultant EDLC exhibited excellent electrochemical performance with energy (58 Wh kg−1) and power densities (55 kW kg−1).

Heat and mass transfer analysis of non-Newtonian power-law nanofluid confined within annulus enclosure using Darcy-Brinkman-Forchheimer model

Non-Newtonian fluids are encountered in many engineering applications, such as the petroleum industry and lubrication. In this investigation, the Magnetohydrodynamic (MHD) and convective boundary (heater) are assumed to analyze the heat transport phenomena of non-Newtonian type Carboxy-Methyl-Cellulose (CMC)/Aluminum oxide (Al2O3) hybrid nanofluid in an annulus enclosure. A porous medium saturates the enclosure under the privileges of Darcy-Brinkman law. Galerkin Finite Element Method (GFEM) is employed for numerical findings. Power-law type non-Newtonian-nanofluid is investigated for different volume fractions (φ) in an aqueous solution of CMC. The flow and the thermal behavior of the nanofluid are investigated for dissimilar values of Rayleigh (Ra), Hartman (Ha), and Darcy (Da) numbers and power-law index (n). The average Nusselt (Nuavg) and Bejan (Beavg) numbers were evaluated for the nanofluid flow. The results indicate that the present composition of nanofluid enhances the heat transfer inside the enclosure. This effect can be further improved by increasing Ra and Da numbers or decreasing the power-law index or magnetic forces. The Da number and power-law index are excellent control parameters for entropy generation. Overall, these results offer a good lead into the design and optimization of thermal performance within an annulus enclosure inundated by a Darcy medium. On the other hand, the outcomes also indicate that, at Ra = 1000, owing to the limited drive of fluid flow inside the cavity, the conduction heat flux is predominant, and the upsurge of the parameter n hasn't a significant effect on Nuavg variations. At the highest Ra, increasing n, and Ha, reduced Nuavg by 50% and 40%, respectively. While increasing, Da improved Nuavg by 245%.

An experimental and theoretical approach on real-time control and monitoring of the apparent viscosity by fuzzy-based control

This paper aimed to develop a real-time monitoring and Fuzzy-based control system for non-Newtonian fluids properties as apparent viscosity. Fuzzy logic was chosen as the control paradigm due to its low implementation complexity compared to other advanced control techniques and its outstanding feature of simplifying the transfer of knowledge from the operator/expert to the control system. To validate the proposed fuzzy control strategy, the authors developed a flow loop system for real-time monitoring and controlling the viscosity of carboxymethylcellulose's aqueous solutions. For apparent viscosity monitoring, a tubular viscometer was developed based on volumetric fluid flow and pressure drop in a defined tube length. The control strategy used in this work was based on Fuzzy Logic, with the Mamdani inference method, which was based on the possibility of transferring the linguistic information from the expert process operator's knowledge to the machine domain language, thus establishing the knowledge basis of the fuzzy controller. The proposed control strategy was validated by experimental tests in a flow loop system, regulator, and servo problems for apparent viscosity. Results showed the Fuzzy controller's satisfactory performance, which proved to be a great potential tool for online monitoring, preparation, and control of the apparent viscosity of drilling fluids.

Evaluation of Thermal Performance of Conically Shaped Micro Helical Tubes Using Non-Newtonian Nanofluids–A Numerical Study

Abstract Nowadays, the cooling and heating of micro-thermal devices have received a growing interest. To improve the thermal management of these micro-thermal devices, various efforts are being made by the researchers. In the present study, conically shaped micro helical tubes are used to investigate the coil side heat transfer rate and friction factor of non-Newtonian nanofluids under laminar flow conditions. For the numerical analysis, single-phase approach with commercial software ansys-fluent-19 has been utilized. Investigations encompass generalized Reynold numbers ranging from 306 to 2159 and four different curvature ratios (0.066, 0.076, 0.088, and 0.1) of conically shaped micro helical tubes. The inner diameter of the helical tube is 2 mm and contains 20 turns. Al2O3-based non-Newtonian nanofluids with volume concentrations of 0.0%, 0.1%, and 0.2% having base fluid of aqueous solution of carboxymethyl-cellulose (CMC) are used as the working fluid (hot) for the coil side, while in the shell side cold water is used. The results from numerical investigation are validated and found in good agreement with earlier experimental results. The results show that with the increase in the curvature ratio of conically coiled tubes both heat transfer rate and friction factor increase by 46% and 98% respectively, for base fluid at a curvature ratio of 0.1. Also, the present study reveals that adding nanoparticles to the base fluid enhances the heat transfer rate to a maximum value of 40%. Moreover, the maximum value of thermal performance factor (TPF) is found to be 1.52.

Stability and uniformity of gas–liquid two-phase flow in shear-thinning fluids in parallelized microchannels

The stability of gas–liquid two-phase flow and uniformity of bubble size in shear-thinning fluids within symmetrical parallelized microchannels are investigated experimentally. Air and sodium carboxymethyl cellulose (CMC) aqueous solutions with 0.3% SDS are used as the dispersed and continuous phases, respectively. The process of gas pressure buildup and rapid release is observed under conditions of exceeding the critical gas and liquid flow rates. Various slug bubble shapes are identified in different concentrations of CMC solutions, gas and liquid flow rates. The results show that the increase of liquid flow rates and the decrease of CMC concentration are beneficial for the stability of bubble formation and uniformity of bubble size in the parallelized microchannels. Finally, semi-empirical formulas are proposed, based on the rheological property of CMC aqueous solutions, to estimate the bubble length.

In Situ Crystallization of Hydroxyapatite on Carboxymethyl Cellulose as a Biomimetic Approach to Biomass-Derived Composite Materials.

Nanohydroxyapatite (HAP) was crystallized in an aqueous solution of carboxymethyl cellulose (CMC) to prepare the composites of CMC and HAP with a stable interface between them with the aim of developing a sustainable tough biomass composite material inspired by bone. The temperature (room temperature to 90 °C) and the concentration of CMC (0.83–13.2 g/L) were optimized for the mechanical properties of the composites. The composite containing 67 wt % HAP prepared at 50 °C in the presence of 9.9 g/L CMC exhibited the largest flexural strength of 113 ± 2 MPa and the elastic modulus of 7.7 ± 0.3 GPa. X-ray diffraction showed that nanometer-sized HAP crystals were formed with a large aspect ratio, and energy-dispersive X-ray spectroscopy and infrared spectroscopy revealed that CMC was bound to the surface of HAP through an ionic interaction between Ca2+ and COO–. Since the composite has a higher flexural strength than polyamide 6 (92 MPa) and a higher elastic modulus than polyamide 6 with 40 wt % glass fiber (5.5 GPa), it can be used as new tough biomass composite material to replace petroleum-derived engineering plastics.

Application of edible coating pretreatment before drying to prevent loss of plant essential oil: A case study of Zanthoxylum schinifolium fruits

In this study, a novel use of edible coating pretreatment before convective hot-air drying to prevent the loss of essential oil (EO) in natural aromatic plant materials was successfully conducted on Zanthoxylum schinifolium fruits. The sodium carboxymethyl cellulose (CMC) aqueous solution was used as the coating material and the effects of its different concentration of 0–2.5% (w/v) on the drying kinetics, total EO content, EO composition and micromorphology of oil chamber were studied. Results showed that increasing concentration of CMC solution significantly increased the total EO retention (p < 0.05) and restricted the change in EO composition. Moreover, the highest CMC solution concentration gave 100% total EO retention, and meanwhile increased the drying time only by 45 min. Therefore, the application of edible coating pretreatment before drying presents a promising method to achieve excellent retention of plant EO.

Preparation and In Vitro and In Vivo Evaluation of a Testosterone Film Forming Gel for the Treatment of Hypoactive Sexual Desire Disorder in Women.

Hypoactive sexual desire disorder (HSDD) is one of the most common sexual complaints in women. Currently, there is an unmet need for a drug treatment for this disorder. The purpose of this study was to develop a testosterone (TS) film forming gel used for women to treat HSDD by measuring the tackiness, peel adhesion force, tensile strength, and elasticity of the formulation. Diethylene glycol monoethyl ether (Transcutol P), an efficient penetration enhancer, was added to the optimized formulation and the transdermal permeation characteristics in vitro were studied using Franz-diffusion cells. The quantitative determination of TS was performed by high-performance liquid chromatography (HPLC). After 24 h, Transcutol P at 3% had the largest cumulative amount of drug and enhancement ratio of TS of 75.14 μg/cm2 and 2.82, respectively. After the screening of film forming polymers and penetration enhancers, the optimal formulation was as follows: glycerol (1%, w/w); 12.5% sodium carboxymethylcellulose (CMC-Na) aqueous solution (0.5%, w/w); 2.5% Carbomer ethanol solution (0.5%, w/w); Transcutol P ethanol solution (3%, w/w) containing 0.5% TS; and 8% Poly vinyl alcohol (PVA) aqueous solution (30%, w/w). The optimized film forming gel had good uniformity and the release of TS in vitro was close to 100% within 24 h. In vivo studies showed the formulations had optimal area under blood drug concentration curve values in the order of 3% Transcutol P > 1% Transcutol P > 5% Transcutol P > control preparation. The formulation with 3% Transcutol P provided the highest permeation effect both in vitro and in vivo. The safety of this formulation was further evaluated with a skin irritation test. It could effectively improve the rabbit skin irritation observed with a marketed transdermal patch Androderm®. The present study provides a promising approach for the development of a novel TS film forming gel for the treatment of HSDD in women.

Experimental and numerical investigations of thermal and flow characteristics of a shear-thinning non-Newtonian fluid in a differentially heated cavity

The thermal and flow characteristics of carboxymethyl cellulose (CMC) were investigated by experimental and numerical means, in order to assess the shear-thinning behaviour of a non-Newtonian fluid inside a differentially heated square cavity. A novel particle image velocimetry technique was used to analyse natural convective flow in a non-Newtonian fluid. The square cavity was filled with an aqueous solution of CMC, which exhibits non-Newtonian shear-thinning behaviour. The present study carried out a comparative analysis of several different numerical models, including the Power-law model, the Cross model, and the Carreau model, with the aim of producing a model that can be used to approximate viscosity distributions for non-Newtonian fluids. Three Rayleigh numbers were considered, Ra=1.22 × 104, 2.29 × 104, and 3.33 × 104. The patterns and magnitudes of velocity obtained from the experimental and numerical analyses were in close agreement in the proximity of the cavity walls and at the core of the natural convective flow. For CMC, the mean Nusselt number (Nu) showed a direct correlation with Ra. The outcomes provide some confidence in terms of their use as benchmark data for the simulation of a non-Newtonian fluid medium. For the first time, the proposed system was applied to non-Newtonian shear-thinning (pseudoplastic) flow, and quantities such as the distribution of mean Nu along the hot wall and the velocity field were determined concurrently for different Rayleigh numbers. Of the three alternative models, the Carreau model is the most effective, and is capable of predicting the thermal and flow performances within the thermal system described here with precision.