Sucrose solution as a new viscous test fluid with tunable viscosities up to 2 Pas for micromixing characterization by the Villermaux–Dushman reaction

For the first time, micromixing characterization for the Villermaux–Dushman reaction could be performed with a non-reactive viscous medium at viscosities up to 2 Pas. As viscous medium, sucrose solution was used with the benefit of being a Newtonian fluid with tuneable viscosity. Due to the higher viscosities in comparison to established media for micromixing investigations, a new protocol for the experimental implementation was developed. Micromixing experiments were conducted and the applicability of viscous sucrose solutions was proven in a stirred tank reactor. Major challenges in characterizing micromixing efficiency in high viscous solution were consolidated.

Tunable Viscoelastic Properties of Sodium Polyacrylate Solution via CO2-Responsive Switchable Water

Upon stimulus by CO2, CO2-switchable viscoelastic fluids experience a deliberate transition between non-viscous and highly viscous solution states. Despite attracting considerable recent attention, most such fluids have not been applied at a large- scale due to their high costs and/or complex synthesis processes. Here, we report the development of CO2-switchable viscoelastic fluids using commercially available sodium polyacrylate (NaPAA) and N,N-dimethyl ethanol amine (DMEA)-based switchable water. Upon bubbling CO2, into the solutions under study, DMEA molecules are protonated to generate quaternary ammonium salts, resulting in pronounced decreases in solutions viscosity and elasticity due to the influence of increased ionic strength on NaPAA molecular conformations. Upon removal of CO2 via introduction of N2, quaternary salts are deprotonated to tertiary amines, allowing recovery of fluid viscosity and elasticity to near the initial state. This work provides a simple approach to fabricating CO2-switchable viscoelastic fluids, widening the potential use of CO2 in stimuli-responsive applications.

Combining new techniques to investigate water dynamics above a shallow restrictive layer.

<p>Adopting integrated measurement techniques may enhance our understanding of hydropedological processes within the critical zone. To investigate lateral subsurface flow due to lithological discontinuities, a ponding infiltration test, two GPR surveys, and soil penetration resistance (PR) measurements were conducted on a 1 m<sup>2</sup> plot in a vegetated area located in the university campus of Doua (Lyon, France). A GPR grid with 0.2 m intervals was established. In the center of the grid, around the root system of a hawthorn shrub, an infiltration test was conducted using an automated single-ring infiltrometer proposed by Concialdi et al. (2020), to infiltrate a shear-thinning viscous solution (1 g L<sup>−1</sup> Xanthan gum powder). The viscous solution was expected to fill preferential pathways due to the roots, with limited infiltration into the soil matrix, and thus reveal complex geometries or macropore networks in highly heterogeneous soils. To create three-dimensional (3D) representations of the infiltrated solution, two GPR surveys were carried out just before and 20 min after the infiltration test, using a GSSI (Geophysical Survey System Inc., Salem, NH) SIR 3000 system with a 900 MHz antenna. A total of 24 radargrams were collected in time mode by moving the antenna along the survey lines and recording the markers position along the survey line intersections. After the second GPR survey, PR was measured at each of the 36 intersection points of the grid using an electronic hand-pushed cone penetrometer. The cone had a 30° angle and a base area of 1 cm<sup>2</sup>, inserted into the soil at a constant speed of 2 cm s<sup>−1</sup> to a depth of 0.8 m. These measurements were aimed to highlight contrasting penetration resistance characteristics between different soil horizons. We also determined the soil bulk density from 24 undisturbed soil cores (~ 100 cm<sup>3</sup>) collected at different depths from 0 to 50 cm. Finally, an auger was used to extract a 0.69-m-depth soil core for the direct observation of lithological heterogeneities.</p><p>Differenced radargrams from pre- and post-infiltration surveys allowed to detect the 3D infiltration bulb, which was vertically elongated and irregularly shaped, but with an evident horizontal divergence between the depth of 20 and 30 cm. Below 30 cm depth, a significant increasing of soil PR and BD (respectively higher than 2.5 MPa and 1.50 g cm<sup>-3</sup>, between 30 and 50 cm depth) was detected, indicating the presence of a underlying layer, which was also identifiable by visual observation of the soil core. This dense layer impeded water flow. Consequently, the liquid solution partially diverged laterally and accumulated upside this layer, and partially infiltrated into the dense layer along preferential flow paths in correspondence with the plant root system, as detected by the 3D GPR diagram. Summing up and considering every aspect, this study allowed to identify water perching above a shallow restrictive layer for a better understanding of the water dynamics of the investigated soil. This study shows the benefits to couple different types of soil physics approaches to relate hydrological processes to the soil hydraulic and mechanical properties.</p>

On a doubly degenerate parabolic equation with a nonlinear damping term

Consider a double degenerate parabolic equation arising from the electrorheological fluids theory and many other diffusion problems. Let $v_{\varepsilon }$ v ε be the viscous solution of the equation. By showing that $|\nabla v_{\varepsilon }|\in L^{\infty }(0,T; L_{\mathrm{loc}}^{p(x)}(\Omega ))$ | ∇ v ε | ∈ L ∞ ( 0 , T ; L loc p ( x ) ( Ω ) ) and $\nabla v_{\varepsilon }\rightarrow \nabla v$ ∇ v ε → ∇ v almost everywhere, the existence of weak solutions is proved by the viscous solution method. By imposing some restriction on the nonlinear damping terms, the stability of weak solutions is established. The innovation lies in that the homogeneous boundary value condition is substituted by the condition $a(x)| _{x\in \partial \Omega }=0$ a ( x ) | x ∈ ∂ Ω = 0 , where $a(x)$ a ( x ) is the diffusion coefficient. The difficulties come from the nonlinearity of $\vert {\nabla v} \vert ^{p(x)-2}$ | ∇ v | p ( x ) − 2 as well as the nonlinearity of $|v|^{\alpha (x)}$ | v | α ( x ) .

Manufacture of a non-woven using bamboo cellulose base (angustifolia) as a filter medium for the manufacture of masks

The purpose of this study was to produce a non-woven, using a base of bamboo cellulose (angustifolia) with a particle size of 1mm, and it begins with the weighing of 100 g bamboo cellulose, which is mixed with a bath ratio bamboo / water 1:10 in a mixer grinder, placing 1 liter of water mixes and forms a viscous solution, this solution is placed on a frame stretched with polyester woven mesh and another frame without mesh, once the layer is formed, it is remove the upper frame without mesh and compress it manually with a sponge, removing excess water and drying in the room at a temperature of 20 0C for 8 hours, evaporated the moisture from the bamboo cellulose (angustifolia) and dried, separated from the frame and a laminated nonwoven (filter) was obtained. Finding that the breaking strength and its elongation in thickness of 0.3mm is 2.73 N and 0.895 mm respectively and thickness of 5mm is 31.2 N and 1.01 mm. The resistance and extension is very low in the two cases, and there are no statistically significant differences between their sample medians (p> 0.05). It can be concluded that when using bamboo cellulose base with a particle size of 1mm, and forming the non-woven with thickness of 0.5mm and 3mm, it has low resistance and extension, finding that if the raw material has an influence on the conformation of the non-woven.

New Approach to Drug Delivery in Ophthalmological Practice: Development of Composite Ophthalmological Solution for Drug Loading of Soft Contact Lenses

Introduction. This article provides a tentative justification of use of soft contact lenses as a carrier of ophthalmological solutions to eye tissues.Aim. The aim of the research is to develop the composition of the ophthalmic transport system for the treatment of glaucoma. Also, the proposed manufacturing algorithms were proposed for drug loading ophthalmological solutions.Materials and methods. Preparation of sodium hyaluronate solution was carried out based on the methodology described in EP 7.0 [01/2011:1472] (Sodium hyaluronate).Results and discussion. The conducted investigation with the purpose to justify a concentration of sodium hyaluronate helped to determine its concentration that gives the viscosity level as close to the upper limit stated in Russian Pharmacopoeia as possible. Buffer solution was chosen with criteria to use as less components in ophthalmological solution as possible. Also, it was found out that the more components are added to the viscous solution, the more viscosity level is decreased. Thus, initial viscosity of solution containing sodium hyaluronate was 149.59 mm2/s, and after addition of active pharmaceutical substance it dropped down to 88.49 mm2/s and 81.36 mm2/s for model solution number 1 and 2, respectively. After addition of citric acid and disodium hydrophosphate, the viscosity of model solution was found to be 78.11 mm2/s and 75.28 mm2/s for model solution number 1 and 2, respectively.Conclusion. As a result of the studies, two alternative model compositions of an ophthalmic solution for the saturation of soft contact lenses for the treatment of glaucoma were proposed. The choice of active pharmaceutical substances, and excipients has been justified. Technological procedure of preparation of model solution was described and explained, where the most attention was paid on dissolving of sodium hyaluronate in purified water.

Concentration profiles around and chemical composition within growing multicomponent bubble in presence of curvature and viscous effects

The regularities of changing chemical composition and size of a ultra-small multicomponent gas bubble growing in a viscous solution have been analyzed. The full-scale effects of solution viscosity and bubble curvature at non-stationary diffusion of arbitrary number of dissolved gases with any value of gas supersaturations and solubilities in the surrounding liquid solution have been taken into account. The nonuniform concentration profiles of gas species in supersaturated solution around the growing bubble with changing composition have been found as a function of time and distance from the bubble center. Equations describing transition to stationary concentrations of gases in the bubble with increasing radius have been obtained. Analytic asymptotic solutions of these equations for a ternary system have been presented.

Mucilage: A Rich Source of Excipients Present in Plant Parts with Gold Status

Large numbers of pharmaceutical excipients of natural origin are available nowadays. Plant materials like mucilages with a variety of pharmaceutical applications are most common. They are being used due to their abundance, safety, compatibility, cost-effectiveness and eco-friendly nature as compared to synthetic one and have various advantages over synthetic polymers. To compete with and replace artificial excipients mucilages can be modified in many ways to obtain the required form of a drug delivery system. Currently, there are a vast amount of natural pharmaceutical excipients are there, and due to its increasing demand, it has become essential to identify or explore more plant mucilage sources to fulfil the industrial need. Mucilages are polymeric mono-saccharides or mixed mono-saccharides combined with uronic acids. On hydrolysis, they yield a mixture of sugars and uronic acids, and the mucilages that are obtained from plant sources have translucent and amorphous nature. Due to presence of hydrophilic moieties in mucilages, they can easily combine with water to form a gel or a thick viscous solution, and these extracted mucilages from the plant can be processed to a certain extent and incorporated in dosage forms to achieve the specific performance of the formulation. In this review, we describe isolation, characterization, pharmaceutical application and methods of modification to develop drug delivery systems.

Long-term follow-up of cystinosis patients treated with 0.55% cysteamine hydrochloride

Background/AimsCystinosis is a rare, autosomal recessive disorder causing defective transport of cystine out of lysosomes. Cystadrops (0.55% cysteamine hydrochloride in viscous solution) has been used on a named-patient basis to treat the accumulation of cystine crystals in the cornea in patients with cystinosis.MethodsRetrospective analysis of the Temporary Authorisation for Use cohort of 130 patients who received Cystadrops between 2013 and 2017 in France.ResultsPatients received an average dosage of 3.3 (±0.94) instillations per eye per day. Over the duration of follow-up, of up to 45 months, patients maintained visual acuity scores of 0.0, which approximated normal. Corneal cystine crystal scores tended to decrease over time, stabilising after around 27 months between 1.22 and 1.87. Photophobia decreased within 3 months, stabilising on scores of around 1.5 and 1.7. 47 non-serious adverse reactions were reported, which were generally transient irritation, stinging or blurred vision. Four serious adverse events were reported, including keratitis and corneal ulcer, but these may have been caused by the underlying disease.ConclusionThis large safety cohort confirms the efficacy, safety and tolerability of Cystadrops in real-world clinical practice.