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| Images of a water droplet sitting on the slices of PVC particles in 0 s, 30 s and 30 min. (a), PVC particles without addition of secondary fluid. (b), PVC particles with 0.09 V% of kerosene. c, PVC particles with 0.09 V% of KSNC.
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According to recent research reports, addition of small amounts of a secondary fluid to a suspension could dramatically increase viscosity of suspension. Results of this study indicate another interesting behavior that the secondary fluid could form a thin hydrophobic membrane around particle surface and significantly decrease the viscosity and yie...
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... study the effect of nanoparticles on rheology of suspensions, the contact angle of PVC particles was measured to verify the changes occurred in hydrophobicity of particles before and after modification. The particles without addition of the secondary fluid gave a contact angle of 80.7 6 1.0u for water (Figure 5a). The water droplets sank through the slice surface in 30 s. ...
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... microstructure of suspension was observed using laser scanning confocal microscope (Nikon A1R). The composite images (Figure 4 of the main text) were created by merging an unfiltered real-light image with a filtered, UV-light image using fluorescent dye stained in the kerosene, as shown in Supplementary Figure S5. The intensity of the UV-light image was marked red in the composite image for clarity. ...
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Citations
... A decreased fluid viscosity by adding suspended particles is not typical behaviour, but it has been observed in rare cases for complex fluids [35,42,43]. Recently, Przekop et al. [33] have shown that plastic microparticles decrease the apparent viscosity of model human mucus. ...
This study aimed to investigate the effect of exogenous nanoparticles on the rheological properties of artificial saliva. There are four reasons for undertaking this type of research: Firstly, the number of solid particles of various origins present in the air is still high. Secondly, nanoparticles (including silver and gold nanoparticles) are increasingly used in food packaging and can migrate into food. Thirdly, saliva is the first biological fluid that comes into contact with exogenous particles. Finally, the function of saliva is also closely related to its rheological properties. Due to the remarkable properties of nano-objects, nanoparticles of various origins in the body may cause effects that have not been realised until now. Therefore, each type of nanoparticle must be tested in terms of its impact on the body/body fluid. We used silver and gold nanoparticles because they are used in the food industry, and diesel exhaust particles because they are standard components of air pollution. The effect of various nanoparticles (e.g., their size and shape) on the rheology of saliva at two temperatures was investigated. The constants of the power law constitutive equation were also estimated. Studies showing the impact of nanoparticles on the rheology of body fluids are rare because it is one of the less obvious ways of their affecting the human body. However, the results show that nanoparticles are not neutral to the biological fluid, which may translate into a change in its properties and thus disturb its functions.
... According to the literature, the inclusion of wettable particles dramatically affects the rheological properties of the blend, causing the viscosity to noticeably reduce as a result of a decrease in the surface energy of melt. [31][32][33] The addition of Mo contributed to a significant decrease in the contact angle to 38 ± 3 • for the Mo-4 sample and 14 ± 2 • for the Mo-8 sample. Interestingly, Mo loading above 8% increased the contact angle to 22 ± 2 • (Mo-12). ...
Ni‐based alloys provide good brazing filler characteristics for the many applications of SiC ceramics. Nevertheless, the presence of graphite is unavoidable in the reaction between Ni and SiC, leading to a significant degradation of the mechanical properties of the joint. This study investigates the effect of Mo in Ni–30Si alloy on the brazing of SiC at 1300°C, to regulate interfacial reactions and reduce residual stresses by decreasing overall coefficient of thermal expansion (CTE) values throughout the brazing process. The addition of Mo up to 8 at.% efficiently suppresses graphite accumulation by converting it into Mo2C + Ni3Mo3C phases and lowering the CTE to 5.4 × 10⁻⁶/°C. When the Mo loading exceeds 12 at.%, the interactions between the filler and SiC are reduced as a result of the non‐homogeneous dispersion of Mo. The experimental findings indicate that the joint without graphite has a lap shear strength of 107 MPa, which is nearly three times greater than the joint with graphite. Thermodynamic analyses are performed to provide a comprehensive understanding of the underlying mechanisms responsible for the formation of distinct phases in brazed joints.
... The effects of nanoparticles on the apparent viscosity of artificial mucus are presented in Figure 4. A decrease in fluid viscosity by adding suspended particles is not typical behavior, but it has been observed in rare cases for complex fluids [32][33][34]. Ben-David et al. [35] recently showed that in jellyfish mucus, the microsized plastic particles do not form a suspension, but are captured by the mucin network. This is a potential reason for changing its mechanical properties, which may affect its mechanical properties and result in a decrease in the apparent viscosity of mucus. ...
Pollution by plastic microparticles is rising rapidly. One avenue of human exposure to nanoparticles is through inhalation. The main source of microplastics in indoor environments, leading to unintended inhalation, is synthetic fabric used in clothing. Other sources include curtains, carpets, furniture, wall paints, and floor finishes. Occupational exposure is particularly significant in waste management and recycling operations, during exposure to high heat, during high-energy treatment of polymer composites, and during 3D printing. In outdoor environments, exposure can happen through breathing in contaminated aerosols from ocean waves or airborne particles from dried wastewater treatments. Airborne particles affect human health in various ways, including via direct interactions with the epithelium and its mucus layer after deposition in the mouth and respiratory system. Exposure due to the ingestion of microplastics present in various environmental compartments may occur either directly or indirectly via the food chain or drinking water. This study aimed to determine the effects of plastic microparticles on the rheology of mucus and saliva, and, thus, their functioning. The experiments used artificial mucus, saliva, and plastic nanoparticles (namely, PS—polystyrene and PE—polyethylene). The rheological properties of saliva and mucus were determined via the use of an oscillatory rheometer at various temperatures (namely, 36.6 °C and 40 °C, which correspond to healthy and ill humans). The results were compared with those obtained for pure saliva and mucus. An increase in apparent viscosity was observed for saliva, which is behavior typical of for solid particle suspensions in liquids. In contrast, for mucus, the effect was the opposite. The influence of the presence of the particles on the parameters of the constitutive viscosity equations was studied. Plastic micro- and nanoparticles in the saliva and mucus may interfere with their physiological functions.
... 7 -8. The decrease of fluid suspension by addition of suspended particles is not typical behavior but was observed in rare cases for complex fluids [22][23][24]. Ben-David et. al. [25] have recently shown, that in jellyfish mucus the microsized plastic particles do not form suspension, but are captured by mucin network, what is potential reason of changing its mechanical properties, what may affect its 8 mechanical properties and result in decrease of apparent viscosity of mucus. ...
The level of air pollution by nano and microparticles raises rapidly. One of the methods of human exposure to nanoparticles is through inhalation. Indoor environments contain airborne plastic particles, primarily from synthetic textiles, leading to unintended inhalation or occupational exposure. In outdoor environments, exposure could happen through breathing in contaminated aerosols from ocean waves or airborne fertilizer particles from dried wastewater treatments. Airborne particles affect human health in various ways and they also act directly on the epithelium and its mucus layer after deposition in the mouth and respiratory system. Exposure via ingestion to microplastics present in the various environmental compartments may occur either directly or indirectly via the food chain or drinking water. The aim of the study was to determine the influence of plastic microparticles on the rheology of mucus and saliva, and thus on their functioning. The artificial mucus and saliva, as and plastic nanoparticles (namely PS – polystyrene and PE - polyethylene) were used in experiments. The rheological properties of saliva and mucus were determined with the use of an oscillatory rheometer, at various temperatures (namely 36.6 C and 40 C, what corresponds to the case of healthy and ill human) The results were compared with those obtained for pure saliva and mucus. The influence of the presence of the particles on the parameters of the constituitive viscosity equations was studied. The presence of plastic micro- and nanoparticles in the saliva and mucus may interfere with their physiological functions.
... Flocculation should be carefully controlled, especially during long-term storage. The viscosity of suspensions should not be too high to make redispersion difficult [37]. To formulate a physical stable suspension, several approaches can be employed, including controlled particle size, the use of structured vehicles, and the use of flocculating agents [38]. ...
More than 50% of approved drugs on the market contain poorly water-soluble APIs, which typically are associated with poor bioavailability, suboptimal drug delivery, ineffective drug efficacy, and side effects. This creates a huge opportunity in generating 505(b)(2) products, which address unmet medical needs by applying formulation technologies to overcome those difficulties. A key feature of the 505(b)(2) pathway is the 505(b)(2) sponsor can rely upon clinical data or literature produced by other companies. The 505(b)(2) pathway allows manufacturers to acquire FDA approval without performing all the work required with a traditional NDA. The 505(b)(2) strategy can be an option to improve existing drug products with a new indication, dosage form, dosing regimen, strength, combination with other products, new route of administration, elimination of food effect, switching from a prescription drugs (Rx) to an over-the-counter (OTC), non-prescription product that differs from the OTC monograph, and orphan drug indications. Both generic and brand companies are turning to more complex 505(b)(2) products to avoid the commoditized generic competition. Revitalization of older marketed drug products using innovative drug delivery technologies or platforms can provide new marketing exclusivity and new patent protection, and thus offer an effective tool for product life cycle management.
... The procedure to reduce viscosity involves many strategies, e.g. adding polydispersity [11] to the particle sizes, changing their shapes [12,13], adding some lubricating particles, by adding another fluid [14] etc.. One recent and successful approach is to apply a cross shear to the suspension as it does not involve a change of a suspension's composition. ...
Dense suspensions tend to shear jam at large packing fractions. However, it has recently been shown that various oscillation protocols can unjam as well as reduce viscosity and dissipation. In this numerical work, we ask ourselves what is the optimum shear protocol in terms of dissipation. We show that many cruising protocols' dissipation are similar to shear protocols with a steady primary shear and superimposed cross oscillations, even though the latter's viscosity reduction is more considerable. Furthermore, we find that alternating between primary and perpendicular oscillations yields a much higher dissipation than the two protocols mentioned above, yet has similar viscosity as the cross-oscillatory one. While self-organization has been shown to minimize viscosity, our findings challenge the idea that random organization is the underlying mechanism for reducing dissipation. Instead, shear ``fragility'' combined with geometry seems to be the key ingredients, which explains the counter-intuitive decoupling of the minima of viscosity and dissipation for the cruising protocol. This work paves the way for a new class of highly-energy efficient flow protocols.
... Another study found that by increasing the concentration of reduced graphene oxide, the resulting solution had a 3% reduction of its surface tension followed by a reduction in apparent viscosity [540]. The addition of PG into the polymer solution may also act as a secondary fluid which improves the hydrophobicity of the particles, this results in an increase in free water in the suspension that significantly reduces the viscosity and yield stress [541]. It is observed that higher loading of PG significantly reduces the viscosity of the polymer solution and at 5 wt%, the viscosity is less than half that of the original PCL solution. ...
Thinner fibres benefit from a high surface area to volume ratio which is valuable in many biomedical applications ranging from tissue engineering to drug delivery and wound healing. Fibre forming technologies such as electrospinning and pressurised gyration rely on the careful manipulation of solution properties as well as working parameters to obtain the most optimal fibre morphology for their intended applications. In deeply understanding how these fibre manufacturing technologies work, there can be highly optimised and tailored production of polymeric biomaterials. Natural substances represent a class of materials that fail to be forgotten for use in health-related applications. Honey and cinnamon have gained significant interest not only for their physical and chemical properties but also for their antibacterial activity. Manuka Honey UMF 20+ was examined for its antibacterial properties against Escherichia coli and Staphylococcus epidermidis using flow cytometry where the active agent is thought to be the high methylglyoxal content. The inhibitory effect of manuka honey on bacterial growth was evident at concentrations ranging from 10 to 30 v/v%, where higher concentrations benefited from additional honey loading. The incorporation of Manuka honey as an antibacterial agent was explored as a potential route for manufacturing wound dressing components. Using pressurised gyration, scaffolds of sub-micrometre fibres were formed from 10, 20 and 30 v/v% Manuka honey which were incorporated into the polycaprolactone polymer solutions. The composite fibres were analysed for their morphology and topography using scanning electron microscopy. The average fibre diameter of the Manuka honey-polycaprolactone scaffolds was found to be in the range of 437 to 815 nm. The antibacterial activity of the most potent 30 v/v% scaffolds was studied against S. epidermidis. The scaffolds showed strong antibacterial activity with a bacterial reduction rate of over 90%. The results here show that honey composite fibres can be considered a natural therapeutic agent for wound healing applications. Fibrous bandage-like constructs made with incorporated cinnamon extract have been previously shown to have potent antifungal abilities which surpass even the raw material itself. The question remains as to whether these constructs are useful in the prevention of bacterial infections and what the antimicrobial effect means in terms of toxicity to native physiological cells. In this work cinnamon-extracted fibres are tested against Staphylococcus epidermidis to assess their antibacterial capacity; it was found that the fibres were able to successfully kill the bacteria. The constructs were also tested under indirect MTT cytotoxicity tests involving the L929 mouse fibroblast cell line, where they showed no variation from the control groups in terms of toxicity. Additionally, cell viability imaging showed no significant toxicity issues with the fibres, even at their tested highest concentration. Here I present a viable method to produce wound healing products made from non-toxic and abundant naturally occurring materials such as cinnamon. Two fibre forming techniques, pressurised gyration and electrospinning have been combined to create a manufacturing process where advanced wound healing bandages can be created. This new hybrid process leverages the rapid production rate of pressurised gyration to create the bulk portion of the bandages and exploits the precise nature of electrospinning to directly print a bioactive fibrous patch onto the active site of the bandages. Polycaprolactone bandages have thus been created which have a bioactive patch consisting of collagen and chitosan with a poly(ethylene oxide) support. The patches have an average fibre diameter of 173 ± 27 nm and closely resemble the extracellular matrix in its structure, together with the active collagen and chitosan, this will be crucial in their ability to facilitate advanced wound healing. Additionally, synthetic materials such as antimicrobial nanoparticles can be added to the patches which demonstrate that the manufacturing technique is not limited to only using natural materials. Patches with these nanoparticles had an average fibre diameter of 142 ± 31 nm and demonstrated that very uniform and thin fibres could be created with these materials. The process has a great degree of automation and has potential for industrial scalability. The advancement of manufacturing processes needs to be supported by the discovery of novel materials and novel combinations of existing materials. Graphene possesses many properties that have predominately been investigated for commercial applications. For the first time, porous graphene (PG) has been incorporated into polymer matrices produced by a high-output manufacturing process. Graphene and its other derivates such as graphene oxide have been shown to provide an antibacterial surface that can mechanically kill pathogens that encounter it. For this reason, graphene nanopores presents itself as a viable additive for wound healing materials. This overarching work focuses on the production of small diameter fibres via multiple techniques to achieve the most control over the final fibre morphology for uses in advanced wound healing materials.
... Rouse et al. [50] modelled a hydraulic jump with air. A more recent approach to change the water properties is based on nanofluids, i.e. nanoparticles are added to water [51,52]. A key advantage of the novel scaling laws is that fluids of different density from water, e.g. ...
The Froude scaling laws have been used to model a wide range of water flows at reduced size for almost a century. In such Froude scale models, significant scale effects for air–water flows (e.g. hydraulic jumps or wave breaking) are typically observed. This study introduces novel scaling laws, excluding scale effects in the modelling of air–water flows. This is achieved by deriving the conditions under which the governing equations are self-similar. The one-parameter Lie group of point-scaling transformations is applied to the Reynolds-averaged Navier–Stokes equations, including surface tension effects. The scaling relationships between variables are derived for the flow variables, fluid properties and initial and boundary conditions. Numerical simulations are conducted to validate the novel scaling laws for (i) a dam break flow interacting with an obstacle and (ii) a vertical plunging water jet. Results for flow variables, void fraction and turbulent kinetic energy are shown to be self-similar at different scales, i.e. they collapse in dimensionless form. Moreover, these results are compared with those obtained using the traditional Froude scaling laws, showing significant scale effects. The novel scaling laws are a more universal and flexible alternative with a genuine potential to improve laboratory modelling of air–water flows.
... Kim & Dabiri (2017) numerically investigated the time evolution of eccentric compound droplets subjected to a simple shear flow. The effects of inertia (Bazhlekov, Shopov & Zapryanov 1995), viscoelasticity (Zhou, Yue & Feng 2006), surfactant laden interfaces (Hamedi & Babadagli 2010;Xu et al. 2013;Srinivasan & Shah 2014;Zhang et al. 2015;Mandal, Ghosh & Chakraborty 2016), confinement (Song, Xu & Yang 2010) and electric field (Soni, Thaokar & Juvekar 2018;Santra, Das & Chakraborty 2020a;Santra et al. 2020b) on compound drops have also been addressed and thus, the literature on compound drops is plentiful. However, the presence of three fluids and multiple deforming interfaces make the analysis of compound drops cumbersome. ...
Compound particles are a class of composite systems in which solid particles encapsulated in a fluid droplet are suspended in another fluid. They are encountered in various natural and biological processes, for e.g. nucleated cells, hydrogels, microcapsules etc. Generation and transportation of such multiphase structures in microfluidic devices is associated with several challenges because of the poor understanding of their structural stability in a background flow and the rheological characteristics of their dispersions. Hence, in this work, we analyse the flow in and around a concentric compound particle and investigate the deformation dynamics of the confining drop and its stability against breakup in imposed linear flows. In the inertia-less limit (Reynolds number, $Re \ll 1$ ) and assuming that the surface tension force dominates the viscous forces (low capillary number, $Ca$ , limit), we obtain analytical expressions for the velocity and pressure fields up to ${O}(Ca)$ for a compound particle subjected to a linear flow using a domain perturbation technique. Simultaneously, we determine the deformed shape of the confining drop correct up to ${O}(Ca^2)$ , facilitating the following. (i) Since ${O}(Ca^2)$ calculations account for the rotation of the anisotropically deformed interface, the reorientation dynamics of the deformed compound particles is determined. (ii) Calculations involving the ${O}(Ca^2)$ shape of the confining interface are found to be important for compound particles as ${O}(Ca)$ calculations make qualitatively different predictions in generalised extensional flows. (iii) An ${O}(Ca)$ constitutive equation for the volume-averaged stress for a dilute dispersion of compound particles was developed to study both shear and extensional rheology in a unified framework. Our analysis shows that the presence of an encapsulated particle always enhances all the measured rheological quantities such as the effective shear viscosity, extensional viscosity and normal stress differences. (iv) Moreover, linear viscoelastic behaviour of a dilute dispersion of compound particles is characterised in terms of complex modulus by subjecting the dilute dispersion to a small-amplitude oscillatory shear (SAOS) flow. (v) Various expressions pertaining to a suspension of particles, drops, and particles coated with a fluid film are also derived as limiting cases of compound particles.
... Rouse et al. [50] modelled a hydraulic jump with air. A more recent approach to change the water properties is based on nanofluids, i.e. nanoparticles are added to water [51,52]. A key advantage of the novel scaling laws is that fluids of different density from water, e.g. ...
