Newtonian Behavior Research Articles

Computational analysis of entropy generation in three-dimensional mixed convection flow with thermal dissipation and variable thermal conductivity

Entropy generation in steady three-dimensional thermal flow is investigated under the coupled influence of viscous dissipation and mixed convection. The stretching sheet with an exponential velocity profile induces the flow. In this examination, we presume that the fluid is incompressible and possesses a Newtonian behavior and temperature-dependent thermal conductivity. Using the appropriate classical similarity variables reduces the dimensional nonlinear dynamical system of governing equations to a dimensionless nonlinear dynamical set of ordinary differential equations. It’s important to note that the selection of an exponentially varying surface temperature is deliberate, as it enables precise similarity transformations to be established in situations involving both viscous dissipation and buoyancy forces. The simplified finite difference approach (SFDM) is used to solve the acquired nonlinear dynamical set of ordinary differential equations. The tridiagonal matrix approach is used to solve the resulting system of algebraic equations. In a particular situation, the present numerical simulation is numerically checked with the previously available results and observed a good agreement. The effects of physical parameters on velocity, temperature, surface stresses and heat tranfer rate, entropy generation, and the irreversibility parameter are investigated. The entropy generation rate exhibits a decreasing trend with respect to the mixed convection parameter in the vicinity of the stretching surface. Entropy reduction can be achieved by employing a working fluid with a low Prandtl number and by minimizing the fluid friction.

Citric Acid-Based Esters as Potential Synthetic Lubricants: A Study of Their Synthesis, Rheological Properties and Thermal Stability

The failure of mineral oils to work in machinery and engines under intense pressure, heat, and corrosion has prompted researchers to consider the development of synthetic lubricating oils that are appropriate for these demanding conditions. This research was conducted to synthesize new esters by reaction of citric acids (CA) with mono-alcohols (hexanol, octanol, decanol and 2-ethylhexanol), then the products were reacted with propanoic acid, valeric acid, and octanoic acid separately using 1:1 molar ratio. The resulting esters were characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The rheological properties were studied, and it was found that the prepared esters have high thermal stabilities as the degradation takes place in the range of 175 °C - 425 °C. The prepared esters show Newtonian behaviors as their viscosities do not change by changing shear rate. The physicochemical characteristic of prepared esters were also determined which showed improved low temperature properties (PP) -36 °C for ester (2R)-1,2-bis(2-ethylhexyl) 3-nonyl 2-(pentanoyloxy)propane-1,2,3-tricarboxylate (COEV) and viscosity index (VI) at 195 for ester (2R)-1-decyl 3-(2-ethylhexyl) 2-heptan-3-yl 2-(propionyloxy)propane-1,2,3-tricarboxylate (CDEP). The stabilities of the prepared esters were confirmed via the computational analysis and their stabilities were ranked as CDEP > COEP > COEO > COEV.

Rheological behaviour of CaO–MgO–SiO2–Al2O3–B2O3 system with varying B2O3 content up to 30 wt% at basicity of 0.4

A comprehensive theoretical and experimental study describing the effect of B2O3 (0–30 wt%) on softening, liquidus, and crystallization temperatures, flow behaviour, and dynamic viscosity of the glass-based oxide system SiO2(64.64–43.21 wt%)-MgO(10 wt%)-CaO(15.86–7.29 wt%)-Al2O3(9.50 wt%)-B2O3 with a constant basicity of 0.4 was carried out. The experimental data was obtained up to 1550 °C using a high-temperature rheometer and were supported by the study of the internal structure by means of scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray powder diffraction analysis, and Fourier transform infrared spectroscopy. The increasing addition of boron oxide caused a decrease in the start and end softening and liquidus temperatures. At 1550 °C, the systems exhibited Newtonian behaviour, with a dynamic viscosity increasing exponentially with a decreasing temperature and decreasing with increasing B2O3 content. The amorphous character of the samples and the formation of structural units [BO2O−] and [BO3] and [BO4], confirmed by complementary analyses, led to a decrease in the degree of polymerization of the silicate structure. The theoretical insight into the dependence of dynamic viscosity on the temperature and composition was realized based on molecular dynamics. Furthermore, the prediction of viscosity as a function of temperature (1230–1550 °C) and the change in chemical composition (0–30 wt% B2O3) was performed using artificial neural networks.

Investigation of thermo-rheological properties of Fe3O4/Ethylene glycol nanofluid in a square cavity

Many fluids used in heat transfer and transport phenomena restrict the effectiveness of heat exchange equipment on account of their low thermal conductivity. Using nanofluids, the ef-fectiveness of heat exchange equipment is enhanced by many folds. The use of magnetic nano-fluids for heat transfer generates a prospect of regulating flow and controlling the thermal and transport properties particularly the thermal conductivity and viscosity using an externally applied magnetic field. The present study involves synthesis of oleic acid-coated magnetic nanofluids at varying concentrations of 0 to 0.643% by volume, measurement of thermal conductivity, rheological properties and corresponding numerical simulation of Nanofluid in a heated square cavity. The thermal conductivity measurement have been carried out by transient hot-wire method using KD2-pro at varying concentrations of solid phase. The re-sults show a significant increase in thermal conductivity with increase in particle concentra-tion. Rheological measurements show variation in viscosity with shear rate, temperature and concentration. Moreover, it has been found that at low particle loading magnetic nanofluids exhibited Newtonian behavior unlike non-Newtonian behavior at increased concentration. Numerical simulation of the magnetic nanofluid in the heated square cavity demonstrates the immense potential of augmentation of heat transfer coefficient using such fluids.

Effect of surfactants on the stability and thermophysical properties of Al2O3+TiO2 hybrid nanofluids

This study investigates the influence of eight distinct surfactants on the stability, rheological characteristics, and thermophysical properties of hybrid nanofluids (NFs) containing Aluminum oxide (Al2O3) and Titanium dioxide (TiO2) in a Water-Ethylene Glycol (EG) mixture (60:40). The objective and novelty of this research is to choose the best surfactant for long run applications in terms of stability, viscosity and thermal conductivity.The results reveal that polyvinylpyrrolidone (PVP) exhibited the highest stability among all surfactants, surpassing others in zeta potential and visual stability over 60 days. Additionally, all the nanofluids exhibited Newtonian behavior. Surfactant addition increased viscosity, with polyethylene glycol (PEG) showing the highest enhancement of 37.2 % at 30 °C. Thermal conductivity increased with temperature, maximum TC enhancement of 8.3 % at 80 °C was given by PEG and oleic acid (OA), but these surfactants were unstable to be used in any application.In conclusion, PVP emerged as the most suitable surfactant for Al2O3-TiO2 hybrid nanofluids due to its exceptional stability, moderate viscosity, and TC enhancement. It enhanced the TC by 3.6% at 80°C and contributed 28.9% in viscosity increment at 30°C. This research contributes to the understanding of surfactant effects on nanofluid properties, particularly highlighting PVP's potential for long-term heat transfer applications.

Rheology of Structured Liquids: Newtonian Behavior

Rheology of Structured Liquids: Newtonian Behavior

Thermal Transport and Rheological Properties of Hybrid Nanofluids Based on Vegetable Lubricants.

Nanofluids based on vegetal oil with different wt.% of carbon nanotubes (CNT), hexagonal boron nitride (h-BN), and its hybrid (h-BN@CNT) were produced to investigate the effects of these nano-additives on the thermal conductivity and rheological properties of nanofluids. Stable suspensions of these oil/nanostructures were produced without the use of stabilizing agents. The dispersed nanostructures were investigated by SEM, EDS, XRD, and XPS, while the thermal conductivity and rheological characteristics were studied by a transient hot-wire method and steady-state flow tests, respectively. Increases in thermal conductivity of up to 39% were observed for fluids produced with 0.5 wt.% of the hybrid nanomaterials. As for the rheological properties, it was verified that both the base fluid and the h-BN suspensions exhibited Newtonian behavior, while the presence of CNT modified this tendency. This change in behavior is attributed to the hydrophobic character of both CNT and the base oil, while h-BN nanostructures have lip-lip "bonds", giving it a partial ionic character. However, the combination of these nanostructures was fundamental for the synergistic effect on the increase of thermal conductivity with respect to their counterparts.

Thermophysical, rheological and dielectric behaviour of stable carbon black dispersions in PEG200

Phase change materials can store or release large amounts of energy during phase change. An increasing number of authors are studying the influence of the dispersion of nanometric particles on these materials. This article presents the design and experimental characterization of temporal stability, thermal conductivity, isobaric heat capacity, phase change transitions, rheological behaviour, and dielectric properties of nano-enhanced phase change materials based on carbon black (CB) dispersions in polyethylene glycol (PEG200) by using polyvinylpyrrolidone (PVP) as surfactant. We studied the temporal stability of carbon black nanoparticles dispersed in PEG200 using dynamic light scattering and spectrophotometry techniques. All the samples showed good temporal stability, since the measurements of the hydrodynamic size of the nanoparticles are practically constant over time and the wavelength observed by UV–vis shows a small variation of around 4% for static conditions. We observed small changes in thermal conductivity and isobaric heat capacity. Nevertheless, the thermograms evidence how the latent heat clearly increases with the load of carbon black nanoparticles up to four times that of the PEG200. The viscosity studies do not show variation with shear rate, indicating a Newtonian behaviour, excluding the 2.0 wt% CB/PVP + PEG200 nanofluid. Additionally, we noticed frequency dependent and independent regions for permittivity.

A comparative experimental investigation of dynamic viscosity of ZrO2/DW and SiC/DW nanofluids: Characterization, rheological behavior, and development of new correlation

In general, A nanofluid is a substance in which solids and fluids are mixed. The nano-powder of zirconium oxide (ZrO2) and silicon carbide (SiC) was dispersed into the distilled water (DW) using the widely adopted two-step technique. A Brookfield viscometer was used to measure the viscosity of the nanoparticles of ZrO2/DW and SiC/DW, where the temperature ranged between 20 and 60 °C and different solid volume fractions of 0.025, 0.05, 0.075, and 0.1 % were used. An examination of the mono nanofluids of ZrO2/DW and SiC/DW was conducted to assess their rheological behaviour. The findings of the experiments revealed that the Newtonian behaviour did not change when the nano-powder was added. Increasing the solid volume fraction of the nanoparticles and lowering the temperature resulted in the sample's dynamic viscosity being augmented. Hence, as the temperature rose, nanoparticles had a more observable impact on the viscosity. Furthermore, the findings showed that the increase in the ZrO2/DW nanofluid's viscosity peaked at 226.3 %, whereas for the SiC/DW nanofluid, it was 110.5 %. Additionally, according to the results of the experiments, new correlations capable of predicting the investigated nanofluids' viscosity in relation to solid concentration and temperature has been suggested. The study's results could motivate expanded utilization of nanofluids by researchers working on energy applications.

Rheological properties of arabinogalactan solutions related to the carbohydrate composition of different legumes

The aim of this study was to elucidate chemical structures and rheological properties of arabinogalactans (AGs) isolated from three legumes including black gram (BG), great northern bean (GNB), and California small white bean (CSWB). The ratio of galactose to arabinose (G/A) in three legumes increased in the order of BG > GNB > CSWB. The rheological measurements of 1-5% (w/v) AG solutions revealed Newtonian and non-Newtonian flow behaviors. BG exhibited yield stress, indicating plastic behavior. Small-amplitude oscillatory tests indicated viscoelastic properties of BG, GNB, and CSWB ranging from solid-like, paste-like, and liquid-like behaviors, respectively. Small-strain oscillatory tests were conducted to assess the structure recovery of the AGs after pre-shearing. G″ values of BG and GNB increased, but those of CSWB remained constant after shearing. These results suggest that the chemical structures of the AGs, particularly their G/A ratios, influence their rheological properties.

Surface tension, wettability and tribological properties of a low viscosity oil using CaCO3 and CeF3 nanoparticles as additives

The rise of the electric vehicles as a more sustainable transport alternative makes it necessary to study new transmission fluids that adapt to their needs and improve their efficiency. The thermophysical properties (contact angle, surface tension and rheology) and tribological properties (friction and wear) of potential PAO8 transmission nanofluids using CaCO3 and CeF3 nanoparticles as additives are evaluated at mass concentrations of 0.05, 0.10, 0.15 and 0.20 wt%. Low contact angle and surface tension values are obtained, indicating good wettability. When the nanoparticles are used as PAO8 additives, small reductions in surface tension are achieved, but no differences in contact angle are observed. All nanolubricants and base oil exhibit Newtonian behavior. Concerning the tribological behavior, reductions in the friction coefficient are achieved for both types of nanoparticles, with the largest reductions comparing to PAO8 base oil being 13 % and 10 % for nanolubricants containing 0.05 wt% CaCO3 and 0.10 wt% CeF3 nanoparticles (NPs), respectively. In terms of antiwear performance, maximum reductions are obtained for the CaCO3 nanolubricant of 28 % (0.15 wt%), 41 % (0.10 wt%) and 59 % (0.15 wt%) and for the CeF3 nanolubricant of 19 % (0.20 wt%), 53 % (0.10 wt%) and 58 % (0.20 wt%) for the parameters of diameter, depth, and area of the worn track, respectively. Through Raman microscopy, the tribological mechanisms of tribofilm formation, repairing, and rolling can be proposed. A discontinuous tribofilm formed by the CaCO3 and CeF3 nanoparticles reduces the contact area between the two surfaces protecting them.

Injectable Gamboge-Based In Situ Gel for Sustained Delivery of Imatinib Mesylate.

The aim of this study was to prepare and characterize the imatinib mesylate (IM)-loaded gamboge-based ISG system for local administration of an anticancer agent against colorectal carcinoma. The ISG formulations were prepared in dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP). The physicochemical properties, drug release profile, and cytotoxicity of the developed formulations were assessed. The developed ISG demonstrated Newtonian flow behavior with acceptable rheological and mechanical properties. The viscosity of the developed ISG, measured at less than 80 cP, and the applied forces of less than 50 N·mm, indicated easy administration using clinical injection techniques. Upon contact with an aqueous phase, the ISG immediately formed a porous cross-sectional structure, enabling sustained release of IM over 14 days. The release profile of IM was fitted to the quasi-Fickian diffusion mechanism, and the release rate could be controlled by the types of solvent and the amount of IM content. The developed IM-loaded gamboge ISG effectively inhibited colorectal cancer cells, including HCT116 and HT29 cell lines, with less than 20% cell viability observed at a concentration of 1% w/w IM after 2 days of incubation. This suggests that the developed ISG may potentially serve as an injectable system for localized anticancer delivery against colorectal cells, potentially reducing the side effects of systemic chemotherapy and improving patient adherence.

Evaluating the properties of a novel diesel-like fuel produced by biochar-assisted catalytic cracking of waste motor oil

In light of the need for sustainable and eco-friendly alternatives to conventional fuels, waste-based diesel-like fuels have emerged as a promising solution. This study explores the chemical, physical, and rheological properties of a diesel-like fuel (DLF) produced via chemical recycling of waste motor oil (WMO) using an alkali-treated rice husk biochar as a catalyst. DLF from biochar-assisted cracking (DLFB) resembles commercial diesel hydrocarbon distribution better than DLF from thermal cracking, which shows to many molecules in the gasoline range. DLFB meets the minimum requirements for commercial diesel as per ASTM standards. The study also presents the rheological properties of the DLFB and its blends with commercial diesel, assessing their flow behavior under various operating conditions. The results indicate that all samples exhibit Newtonian behavior. The shear stress rises with the shear rate in a linear manner. Moreover, rheograms indicate that viscosity gradually decreasing with temperature. The obtained DLFB resembles commercial diesel in chemical composition when analyzed via through FTIR and GC-MS analysis, though with a small presence of low-molecular-weight hydrocarbons. In summary, these results demonstrate the potential of this novel DLFB as a sustainable fuel, given its favorable properties and the circular approach applied to the valorization of WMO. Highlights Biomass-based catalytic recycling of waste motor oil to obtain diesel-like fuels (DLFs). DLFB meet commercial diesel standards and exhibit favorable rheological properties. DLFB potential as sustainable fuel with a similar composition to commercial diesel.

Experimental study and gradient-based ensemble intelligent computing to investigate effect of ultrasound on rheological behavior of bio-based phase change materials

The influence of ultrasound on the rheological behavior of new phase change material (PCM) is investigated. The PCMs are made from natural biological materials containing silicon carbide (SiC) nanoparticles or expanded graphite (EG) powders with weight fractions of 0, 0.05, 0.1, and 0.2 %. The rheological behavior of PCM composites is tested by a rheometer with shear rates of 10 up to 250 rpm. Surveys showed the smallest PCMs' viscosity at shear rates over 100 rpm is obtained for the highest sonication time. Results depict an ignorable change in the dynamic viscosity of PCMs with shear rate, and the shear thinning behavior reduces the PCMs' viscosity by raising the shear rate by 10–140 rpm. Results for EG/PCM and SiC/PCM composites showed non-Newtonian behavior at low shear rates. However, steadiness in viscosity at a shear rate higher than 140 rpm is observed for the Newtonian behavior of PCMs. The other outstanding consequence of this study is the development of novel robust machine learning, namely CatBoost, to simulate the rheological behavior of understudy nano-PCMs based on the weight fraction, sonication time, and shear rate. The multigene genetic programming (MGGP) as a comparative model is adopted to validate the primary model and provide a relationship for estimating the viscosity of each nano-PCMs. Simulation results revealed the superiority of the CatBoost (PCM-EG: R = 0.978 and RMSE = 1.739 mPa·s; PCM-SiC: R = 0.996 and RMSE = 0.374 mPa·s) to the MGGP (PCM-EG: R = 0.967 and RMSE = 2.103 mPa·s; PCM-SiC: R = 0.992 and RMSE = 2.368) in PCM composites.

Surface dynamics and thermophysical mechanics on Reiner–Philippoff fluid flow

Due to high sensitivity of fluid particles to temperature changes, the thermophysical characteristics of fluids are known to exhibit significant variations when exposed to temperature rise, which can impact the overall efficiency of conveying fluid substances in manufacturing processes across different surfaces and media. Industrial and mechanical processes such as aerodynamic extrusion in plastic sheets, fiber technology and biological dynamics as transpiration and muscle cramps exhibit different surface dynamics. The Reiner–Philippoff (RP) fluid model exemplifies shear-thinning, shear-thickening and Newtonian behavior. This study investigates the flow of a RP fluid over a stretching and shrinking surface with nonlinear thermal convection and variable thermophysical properties. The mathematical models describing the dynamical system are transformed through a similar group of transformations. Flow variables such as the fluid’s velocity, temperature and solute concentration were numerically obtained through the spectral local linearization technique (SLLM). Subject to the validation and accuracy of the numerical results, the effects of pertinent parameters on the flow were investigated. The findings in this study reveal that the effects of the flow variables on stretching and shrinking sheets are not diametrically opposite. Moreover, the radiation negatively impacts the flow variables over a stretching sheet compared to the positive effect experienced at some point in flow over a shrinking sheet.

Emerging Newtonian potential in pure R2 gravity on a de Sitter background

In [27] Alvarez-Gaume et al. established that pure mathcal{R} 2 theory propagates massless spin-2 graviton on a de Sitter (dS) background but not on a locally flat background. We build on this insight to derive a Newtonian limit for the theory. Unlike most previous works that linearized the metric around a locally flat background, we explicitly employ the dS background to start with. We directly solve the field equation of the action {left(2kappa right)}^{-1}int {d}^4xsqrt{-g}{mathcal{R}}^2 coupled with the stress-energy tensor of normal matter in the form Tμν = Mc2δ( overrightarrow{r} ) {delta}_{mu}^0{delta}_{nu}^0 . We obtain the following Schwarzschild-de Sitter metric d{s}^2=-left(1-frac{Lambda}{3}{r}^2-frac{kappa {c}^2}{48pi Lambda}frac{M}{r}right){c}^2d{t}^2+{left(1-frac{Lambda}{3}{r}^2-frac{kappa {c}^2}{48pi Lambda}frac{M}{r}right)}^{-1}d{r}^2+{r}^2d{varOmega}^2 which features a potential V(r)=-frac{kappa {c}^4}{96pi Lambda}frac{M}{r} with the correct Newtonian tail. The parameter Λ plays a dual role: (i) it sets the scalar curvature for the background dS metric, and (ii) it partakes in the Newtonian potential V(r). We reach two key findings. Firstly, the Newtonian limit only emerges owing to the de Sitter background. Most existing studies of the Newtonian limit in modified gravity chose to linearize the metric around a locally flat background. However, this is a false vacuum to start with for pure mathcal{R} 2 gravity. These studies unknowingly omitted the information about Λ of the de Sitter background, hence incapable of attaining a Newtonian behavior in pure mathcal{R} 2 gravity. Secondly, as Λ appears in V(r) in a singular manner, viz. V(r) ∝ Λ−1, the Newtonian limit for pure mathcal{R} 2 gravity cannot be obtained by any perturbative approach treating Λ as a small parameter.

A comparative study on emulsification in the presence of a nanoclay (Pickering emulsion) or a surfactant using high intensity mixing

The study explored the potential of using a nanoclay, Laponite RD, as a stabilizing agent in comparison to a surfactant, Tergitol TMN6, at dispersed phase volume fractions of 10–50% vol. An ultrasonicator was employed as an energy intensive device; covering a specific power input range of ∼ 36–52 W kg− 1. In both cases, final dispersions obtained could be considered stable over the period of ageing tests for 3 months as comparable drop size distributions were obtained although there were some differences in the rheology at the highest dispersed phase concentration. Whilst surfactant stabilized emulsions were of Newtonian behavior, Pickering emulsions stabilized with the nanoclay exhibited non-Newtonian behavior, which may be a desirable feature of the final product- certainly one that requires attention in design and scale up. Kinetics of breakup studied through the evolution of the Sauter mean diameter prior to reaching an equilibrium value on the basis of energy density have shown the breakup process being faster with the Pickering emulsions although the equilibrium drop diameters were larger. Overall, with emulsions stabilized using a surfactant, Sauter mean drop diameters could be as low as 240 nm, regardless of the dispersed phase volume fraction, drop sizes were larger with Pickering emulsions which depended on the dispersed phase concentration.

Altered blood rheology in multiwidth microchannels: Hematocrit and tonicity variation

We present a theoretical model for the characterization of the behavior of Newtonian and non-Newtonian fluids inside a microchannel with segments of different widths. This allows us to find the relation required to have collapsed viscosity curves for different fluids in just one experiment. Diverse experiments have been carried out with our setup. We consider different hematocrit concentration samples as well as samples of blood altered with different solutions in order to modify their tonicity. The data are acquired using microscale electronic detection of a fluid/air front advance. This will disclose different diseases that can be distinguished by the change in the normal rheological characteristics of blood or plasma. The results obtained demonstrate that using our setup and mathematical model, we can both distinguish blood with different concentrations of erythrocytes as well as discriminate when a same sample of blood is non-altered, altered with sodium chloride (NaCl) or de-ionized water (DIW), which emulates the abnormalities in the red blood cells of some pathologies. The results show that DIW causes blood to have more non-Newtonian behavior. On the other hand, NaCl causes the sample to become a hypertonic solution, causing the red blood cells to crenate, causing the blood to have a more Newtonian behavior.

Evaluation the injectability of injectable microparticle delivery systems on the basis of injection force and discharged rate

BackgroundSubcutaneous injection of biopharmaceutical agents or microparticles is challenging due to issues with low injection efficiency and high residual amounts. ObjectiveThis study aimed to determine the important factors affecting the injectability of microparticle delivery systems, establish a suitable injection system with lower injection force and higher discharge rate, and eventually develop a reliable injectability evaluation system for injectable microparticle delivery systems in vitro and in vivo. MethodsThe effects of various parameters, including particle size, injection speed, concentration of microspheres suspension, vehicle viscosity, needle length and gauge were evaluated by measuring the injection force and discharge rate. The characteristics of microparticles and rheological measurement of the suspension systems were studied. A design of experiment approach was utilized to evaluate the interaction between the microsphere suspension, vehicle viscosity and needle gauges. Both in vitro sieve tests and in vivo tests in rats were conducted to evaluate injectability. ResultsThe in vitro test results showed that the vehicle viscosity and injection speed have varying effects on discharge rate and injection force, respectively. Particle size and needle gauge have substantial influence on injectability, larger particle size and smaller needle gauges resulting in poor injectability, while the needle gauge was found to have the greatest influence on injectability. Levonorgestrel (LNG) microsphere and glass bead were relatively uniform spherical, the glass bead had extremely smooth surface; while mesoporous silica had irregular shape. The settling rate of glass bead was the fastest, which was about 18 times faster than the LNG microsphere. The CMC-Na had a poor interaction with the LNG microspheres, glass bead and mesoporous silica and showed basically Newtonian behavior in the shear rate range of 0.1 s−1–100 s−1. When shear rate increased to more than 100 s−1, no obvious shear thinning behavior was observed. CMC-Na formed a nodule structure with whether LNG microspheres or the glass beads, which were much lower than that with the mesoporous silica in static state, among which the glass beads were the weakest. The viscosity of the suspension increased with the rising of the volume fraction of particles. Fundamentals of hydrodynamics in capillaries were referenced, such as Navier-Stokes Law equation, Krieger-Dougherty (K-D) equation, Hagen-Poiseuille equation. The best results achieved was using a suspension concentration of 120–240 mg /mL and a viscosity of 60 cP at 20 °C with 23-gauge needles. The optimized conditions were verified in vivo tests. It was proven that the LNG microsphere suspension had a good injectability when injected into subcutaneous tissue of rats. ConclusionThe injection system of injectable microparticle delivery system with lower injection force and higher discharge rate was established and the evaluation method was suitable for the injectability evaluation both in vivo and in vitro. Improved injectability would promote the clinical translation of microparticle delivery systems.

Physicochemical and functional properties of rainbow trout (Oncorhynchus mykiss) hydrolysate

Due to the continuous growth of the world population, there is an urgent need to find sustainable sources of high-quality protein. Fish side streams rich in essential nutrients and accounting for 60–70% of the whole fish, represent a sustainable source for recovery of valuable protein compounds. The present study aimed at extensive characterization of physicochemical, antioxidant and techno-functional properties of fish protein hydrolysate (FPH) obtained from farmed rainbow trout (Oncorhynchus mykiss). The FPH was produced from a minced rainbow trout raw material by enzymatic hydrolysis performed at 50 °C with addition of 0.05% w/w papain and 0.05% w/w bromelain. After inactivation of the proteases at 90 °C for 10 min, the content of the bioreactor was centrifuged, and the soluble protein fraction (FPH) was collected and freeze-dried. The total protein content of the FPH with 17.24% degree of hydrolysis was high (88.9%) and mainly represented by water-soluble proteins, while the lipid content was below 1%. In addition to the high protein content, trout hydrolysate had low protein oxidation values characterized by a relatively low total carbonyl content together with high amount of thiol groups (3.64 ± 0.31 and 20.7 ± 0.6 nmol/mg protein, respectively). No glass transition was detected in the differential scanning calorimetry (DSC) heat flow curves, suggesting lack of unfreezable solution formation in the FPH at freezing temperatures. The viscosity of FPH showed typical Newtonian behaviour. A peptidomic investigation (using HPLC-MS/MS technique) displayed chemical composition of the trout hydrolysate and identified peptide sequences which are present in the hydrolysate mixture, as well as proteins to which each peptide belongs to. In conclusion, it was suggested to use the obtained trout hydrolysate as a functional ingredient in the food and nutraceutical industry.