Conventional Homogenization Research Articles

A stochastic two-scale model for pressure-driven flow between rough surfaces

Seal surface topography typically consists of global-scale geometric features as well as local-scale roughness details and homogenization-based approaches are, therefore, readily applied. These provide for resolving the global scale (large domain) with a relatively coarse mesh, while resolving the local scale (small domain) in high detail. As the total flow decreases, however, the flow pattern becomes tortuous and this requires a larger local-scale domain to obtain a converged solution. Therefore, a classical homogenization-based approach might not be feasible for simulation of very small flows. In order to study small flows, a model allowing feasibly-sized local domains, for really small flow rates, is developed. Realization was made possible by coupling the two scales with a stochastic element. Results from numerical experiments, show that the present model is in better agreement with the direct deterministic one than the conventional homogenization type of model, both quantitatively in terms of flow rate and qualitatively in reflecting the flow pattern.

Influence of Binder Adhesion Ability on the Performance of Silicon/Carbon Composite as Li-Ion Battery Anode

A series of anodes for Li-ion battery was prepared by conventional homogenization of active material, percolator, and Na-CMC or several kinds of PVDF as a binder. Si/C composite was synthesized by embedding micro-sized silicon and synthetic battery-grade graphite in a pitch-derived carbon matrix and taken as active material. Adhesion strength of anodic film to a current collector was determined by peeling test. Thermal relaxation (120-180 °C) after calendering of PVDF-based anode slightly increases the adhesion of the film to the collector. The highest peeling strength was recorded for ultrahigh molecular weight PVDF (~0.05 N cm−1) but without advantage for cycling stability of the cell. An initial reversible capacity of 512 mAh g−1, with average capacity decay only of 0.5% per cycle, was achieved for CMC-based anode of moderate peeling strength (~0.035 N cm−1). Such good performance was attributed to a specific Si/C composite structure as well as profitable physicochemical properties of the binder.

Ultra-High Pressure Homogenization improves oxidative stability and interfacial properties of soy protein isolate-stabilized emulsions

Ultra-High Pressure Homogenization (100–300MPa) has great potential for technological, microbiological and nutritional aspects of fluid processing. Its effect on the oxidative stability and interfacial properties of oil-in-water emulsions prepared with 4% (w/v) of soy protein isolate and soybean oil (10 and 20%, v/v) were studied and compared to emulsions treated by conventional homogenization (15MPa). Emulsions were characterized by particle size, emulsifying activity index, surface protein concentration at the interface and by transmission electron microscopy. Primary and secondary lipid oxidation products were evaluated in emulsions upon storage. Emulsions with 20% oil treated at 100 and 200MPa exhibited the most oxidative stability due to higher amount of oil and protein surface load at the interface. This manuscript addresses the improvement in oxidative stability in emulsions treated by UHPH when compared to conventional emulsions.

Tracking the effect of microspheres size on the drug release from a microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot in vitro and in vivo

The effects of particle size of microspheres on the drug release from a microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot (m-SAIB) was investigated to develop a long-term sustained release drug delivery system with low burst release both in vitro and in vivo. A model drug, risperidone, was first encapsulated into PLGA microspheres with different particle sizes using conventional emulsification and membrane emulsification methods. The m-SAIB was prepared by dispersing the risperidone-microspheres in the SAIB depot. The drug release from m-SAIB was double controlled by the drug diffusion from the microspheres into SAIB matrix and the drug diffusion from the SAIB matrix into the medium. Large microspheres (18.95 ± 18.88 µm) prepared by the conventional homogenization method exhibited porous interior structure, which contributed to the increased drug diffusion rate from microspheres into SAIB matrix. Consequently, m-SAIB containing such microspheres showed rapid initial drug release (Cmax = 110.1 ±54.2 ng/ml) and subsequent slow drug release (Cs(4–54d)= 2.7 ± 0.8 ng/ml) in vivo. Small microspheres (5.91 ± 2.24 µm) showed dense interior structure with a decreased drug diffusion rate from microspheres into SAIB matrix. The initial drug release from the corresponding m-SAIB was significantly decreased (Cmax = 40.9 ± 13.7 ng/ml), whereas the drug release rate from 4 to 54 d was increased (Cs(4–54d)=4.1 ± 1.0 ng/ml). By further decreasing the size of microspheres to 3.38 ± 0.70 µm, the drug diffusion surface area was increased, which subsequently increased the drug release from the m-SAIB. These results demonstrate that drug release from the m-SAIB can be tailored by varying the size of microspheres to reduce the in vivo burst release of SAIB system alone.

Homogenization of composites using full-wave point-dipole model

We propose a full-wave point-dipole-based scheme for accurate material homogenization of composites. Unlike conventional homogenization approaches which employ periodic boundary conditions for the effective permittivity extraction, the proposed technique can efficiently compute the interactions between the scatterers even in inhomogeneous mixtures as well as aperiodic arrangement of a finite number of scatterers. The method utilizes each inclusion as a basis function, and thereby sidesteps the computational burden to discretize each inclusion scatterer. In addition, the supplementary analytical calculations provide closed-form expressions to deal with the field singularities and to calculate the mutual interaction between the scatterers. We demonstrate that the proposed homogenization scheme can precisely extract the composite permittivity profile of a finite size specimen.

Vegetable protein isolate-stabilized emulsions for enhanced delivery of conjugated linoleic acid in Caco-2 cells

Developing edible delivery systems which offer higher protection and release of bioactive constituents is a current challenge in the food industry. The ability of oil-in-water emulsions (20% oil) stabilized by soy or pea protein isolates (4%) to deliver conjugated linoleic acid (CLA, 6%), was studied. The emulsions were prepared by conventional homogenization (550 bar) using one or five homogenization passes. The physicochemical properties of the emulsions were determined, as well as loading capacity and oxidative stability. The emulsions were subjected to in vitro digestion, and tested on absorptive Caco-2 cells. The presence of CLA isomers was followed throughout the process. When comparing similar treatments, soy protein isolate emulsions showed smaller particle size distributions than emulsions prepared with pea protein isolates. Emulsions containing soy proteins showed preferential adsorption of the α′ subunit of conglycinin and the A1, A2, A4 subunits of glycinin on the oil droplets. All emulsions protected the encapsulated CLA better than the non-emulsified control in which CLA was oxidized during storage, as well as after in vitro digestion and delivery in Caco-2 cells. Similar percentages of bioaccessibility and bioavailability of CLA were found for all the emulsion treatments. The results obtained here open new prospects for using oil-in-water emulsions as structured emulsion-based delivery systems to be used in functional foods containing CLA with health enhancing properties.

Physical and oxidative stability of whey protein oil-in-water emulsions produced by conventional and ultra high-pressure homogenization: Effects of pressure and protein concentration on emulsion characteristics

Oil-in-water pre-emulsions (15% sunflower + 5% olive oils) obtained by colloid mill homogenization (CM) at 5000 rpm using whey protein isolate at different levels (1, 2 and 4%) were stabilized by ultra high-pressure homogenization (UHPH, 100 and 200 MPa) and by conventional homogenization (CH, 15 MPa). Emulsions were characterized for their physical properties (droplet size distribution, microstructure, surface protein concentration, emulsifying stability against creaming and coalescence, and viscosity) and oxidative stability (hydroperoxide content and thiobarbituric acid reactive substances, TBARs) under light (2000 lux/m2 for 10 days). UHPH produced emulsions with lipid droplets of small size in the sub-micron range (100–200 nm) and low surface protein with unimodal distribution when produced at 4% whey proteins and 200 MPa. All emulsions exhibited Newtonian behavior (n ≈ 1). Long term physical stability against creaming and coalescence was observed in UHPH-emulsions, compared to those obtained by CM and CH. However, CH emulsions were highly stable against creaming (days) in comparison to the CM emulsions (hours). UHPH resulted in emulsions highly stable to oxidation compared to CM and CH treatments, especially when 100 MPa treatment was applied. Industrial relevance In the food, cosmetic and pharmaceutical sectors, industrial operators are currently interested in developing encapsulating systems to delivery bioactive compounds, which are generally hydrophobic, unstable and sensitive to light, temperature or/and oxygen. Ultra high-pressure homogenization is capable of producing stable submicron emulsions (< 1 μm) with a narrow size distribution, inducing more significant changes in the interfacial protein layer thus preventing droplet coalescence and also inhibit lipid oxidation. The present study suggests that emulsions produced by whey protein (4%) treated by ultra high-pressure homogenization have a good physical stability to flocculation, coalescence and creaming and also high stability to lipid oxidation, opening a wide range of opportunities in the formulation of emulsions containing bioactive components with lipid nature.

Ultra-High Pressure Homogenization enhances physicochemical properties of soy protein isolate-stabilized emulsions

The effect of Ultra-High Pressure Homogenization (UHPH, 100–300MPa) on the physicochemical properties of oil-in-water emulsions prepared with 4.0% (w/v) of soy protein isolate (SPI) and soybean oil (10 and 20%, v/v) was studied and compared to emulsions treated by conventional homogenization (CH, 15MPa). CH emulsions were prepared with non-heated and heated (95°C for 15min) SPI dispersions. Emulsions were characterized by particle size determination with laser diffraction, rheological properties using a rotational rheometer by applying measurements of flow curve and by transmission electron microscopy. The variation on particle size and creaming was assessed by Turbiscan® analysis, and visual observation of the emulsions was also carried out. UHPH emulsions showed much smaller d3.2 values and greater physical stability than CH emulsions. The thermal treatment of SPI prior CH process did not improve physical stability properties. In addition, emulsions containing 20% of oil exhibited greater physical stability compared to emulsions containing 10% of oil. Particularly, UHPH emulsions treated at 100 and 200MPa with 20% of oil were the most stable due to low particle size values (d3.2 and Span), greater viscosity and partial protein denaturation. These results address the physical stability improvement of protein isolate-stabilized emulsions by using the emerging UHPH technology.

Effect of homogenization treatment on microstructure and mechanical properties of DC cast 7X50 aluminum alloy

The evolution of the eutectic structures in the as-cast and homogenized 7X50 aluminum alloys was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), differential scanning calorimetry(DSC), X-ray diffraction(XRD) and tensile test. The results show that the main phases are S(Al2CuMg), T(Al2Mg3Zn3) and MgZn2, with a small amount of Al7Cu2Fe and Al3Zr in the as-cast 7X50 alloy. The volume fraction of the dendritic-network structure and residual phase decreases gradually during the homogenization. After homogenization at 470 °C for 24 h and then 482 °C for 12 h, the T(Al2Mg3Zn3) phase disappears and minimal S(Al2CuMg) phase remains, while almost no change has happened for Al7Cu2Fe. There is a strong endothermic peak at 477.8 °C in the DSC curve of as-cast alloy. A new endothermic peak appears at 487.5 °C for the sample homogenized at 470 °C for 1 h. However, this endothermic peak disappears after being homogenized at 482 °C for 24 h. The T(Al2Mg3Zn3) phase cannot be observed by XRD, which is consistent with that T phase is the associated one of S(Al2CuMg) phase and MgZn2 phase. The volume fraction of recrystallized grains is substantially less in the plate with pre-homogenization treatment. The strength and fracture toughness of the plate with pre-homogenization treatment are about 15 MPa and 3.3 MPa·m½ higher than those of the material with conventional homogenization treatment.

Nonlinear waves in a self-gravitating charge-varying collisional dust molecular cloud in presence of diverse equilibrium inhomogeneities

An evolutionary model for investigating the nonlinear gravito-electrostatic waves in a self-gravitating inhomogeneous planar collisional dust molecular cloud on the Jeans scales of space and time is theoretically proposed. It includes dust-charge variation and weak but finite inertia of the thermal electrons and ions. All the equilibrium gradients and inhomogeneities arising from the dynamics of the electrons, ions, neutral and charged grains are considered simultaneously for the first time. So, any conventional homogenization assumption for mathematical simplification is avoided. By standard inhomogeneous multiple scaling techniques, it is methodologically shown that the fluctuations are collectively governed by a new gravito-electrostatically coupled pair of driven Korteweg–de Vries (d-KdV) equations with new gradient-driven variable coefficients and self-consistent linear sources. A numerical analysis portrays the eigenmode excitations as oscillatory shock- and soliton-like structures. In addition, depending on the explicit regions of the varied plasma parameter space and inhomogeneities, a new shape-transition from soliton to shock and vice versa occurs. Our nonlinear wave analyses could be applied to explain multispace satellite observations and predictions made by others in the past.

Numerical evaluation of micro-structural parameters of porous supports in metal-supported solid oxide fuel cells

Metallic supported Solid Oxide Fuel Cells (SOFCs) are considered as a durable and cost effective alternative to the state-of-the-art ceramic supported cell designs. In order to understand the mass and charge transport in the metal-support of this new type of cell a novel technique involving X-ray tomography and micro-structural modelling is presented in this work. The simulation technique comprises a novel treatment of the boundary conditions, which leads to more accurate effective transport parameters compared to those, which can be achieved with the conventional homogenisation procedures. Furthermore, the porosity distribution in the metal-support was determined, which provided information about the inhomogeneous nature of the material. In addition to that, transport parameters for two identified, different dense layers of the metal-support are evaluated separately.The results of the evaluation show three significant findings. Firstly, that the effective transport parameters are up to a factor of 20 lower compared to other SOFC anodes. Secondly, that the micro-structure can have regions, which are much denser, especially the first 100 μm of the interface between gas-channel and support-structure. Thirdly, that the calculation of the transport parameters depends on the correct application of boundary conditions.

Tensile behavior of 3104 aluminum alloy processed by homogenization and cryogenic treatment

The mechanical properties of 3104 aluminum alloy processed by different combinations of cryogenic and homogenization treatments were studied. The 3104 aluminum alloy processed by the cryogenic treatment followed by homogenization exhibited an enhancement in the tensile strength, yield strength, and elongation by 29%, 41%, and 11%, respectively, as compared with a sample processed by the conventional homogenization treatment. The stress–strain curve of the sample processed by the homogenization treatment exhibited the Portevin–Le Chatelier effect, whereas the sample processed by the cryogenic treatment did not. Further, the cryogenic treatment could accelerate the precipitation of secondary phase particles for the sample processed by a deep cryogenic treatment, followed by a homogenization treatment, which enhanced the dislocation pinning effect of the solvent atoms and thus improved the critical strain.

Biodegradable uniform microspheres based on solid-in-oil-in-water emulsion for drug delivery: A comparison of homogenization and fluidic device

Based on solid-in-oil-in-water emulsification, we fabricated biodegradable poly(ϵ-caprolactone) microspheres containing gentamicin using conventional homogenization and a fluidic device. The feasibility of the poly(ϵ-caprolactone) microspheres as drug carriers was evaluated in terms of encapsulation efficiency, release behavior of gentamicin, and antimicrobial activity. The poly(ϵ-caprolactone) microspheres prepared using a fluidic device (fluidic device microspheres) had a uniform diameter and a smooth surface, whereas the poly(ϵ-caprolactone) microspheres prepared using conventional homogenization (conventional homogenization microspheres) exhibited polydisperse and a porous structure. At 0.3 wt% of gentamicin concentration, the encapsulation efficiencies of the conventional homogenization and fluidic device microspheres were 39.5% and 72.0%, respectively. In addition, a significant amount of gentamicin was only released initially from the conventional homogenization microspheres, whereas the fluidic device microspheres released gentamicin in a sustained manner for 28 days. These results confirmed the superior performances of the uniform fluidic device microspheres for drug delivery system. We further proposed a model for microsphere formation to explain the difference in performance of the conventional homogenization and fluidic device microspheres.

Effect of dynamic high pressure on milk fermentation kinetics and rheological properties of probiotic fermented milk

Abstract This work studied the fermentation kinetics and the rheological behavior of gel formation during fermentation and storage. The milk (2% v/v fat) was subjected to conventional homogenization (15/5 MPa, control treatment) and dynamic high pressure (50/5 MPa, 100/5 MPa, 150/5 MPa and 180/5 MPa), and fermented by Streptococcus thermophilus in co-culture with Lactobacillus acidophilus . The results showed that dynamic high pressure (DHP) did not alter the fermentation kinetics (p > 0.05). However, the rheological behavior during fermentation showed that higher pressures increased the consistency. During storage, an increase of 15% in the consistency index (K′) and a reduction of 31% in the gel syneresis were observed for samples processed at 180/5 MPa, as compared to the control ones (124.67 Pa·s n′ ; 13.5%). After the 28th day, these differences increased up to 27% and 40%, respectively. It is concluded that DHP promotes an increase in consistency and reduction syneresis of fermented milk without changing the fermentation. Industrial relevance The use of DHP allows to increase the consistency of probiotic fermented milk without the addition of any additive. Thus, the product would attend to the probiotic's consumer market, which demands high quality products, with a reduced amount of fat (2%), high consistency and without addition of other ingredients. Furthermore, the DHP does not affect the product fermentation, which would facilitate its direct implementation in the industry.

Green alternative aluminum extrusion process through process convergence

Green manufacturing is very important to reduce the environmental pollution and the material loss. Porthole extrusion is a useful process for producing a long aluminum cylinder tube. In this process, the initial billet is homogenized at a high temperature for a long time to improve the extrudability. The homogenization process is not only a high energy-consuming process but also a high pollution process. Therefore, an alternative process is needed for green manufacturing. In this study, a new porthole extrusion for green manufacturing was developed to reduce the energy consumption through the convergence of the homogenization heat treatment process and the billet pre-heating process. The flow stress of the initial billets with the conventional homogenization heat treatment process and the proposed converged process were obtained through the hot compression test. FE analysis was performed to assess the application of the proposed method. Through FE analysis the extrusion load, material flow, temperature, effective strain, and welding pressure were compared with each other. Finally the porthole extrusion experiment was carried out based on the result of FE analysis. As a result, it can be seen that the aluminum cylinder tube without defect can be produced by applying the proposed green extrusion process.

Application of Hydrothermal Diamond Anvil Cell to Homogenization Experiments of Silicate Melt Inclusions

The homogenization of silicate melt inclusions (SMIs), small droplets of silicate melt trapped in magmatic minerals, is an important component of petrogenetic and magmatic research. Conventional homogenization experiments on SMIs use microscope-mounted heating stages capable of producing high temperatures at 1 atm and cold-seal high-pressure vessels. Heating stages are generally used for SMIs with low internal pressures and allow in situ observations of the homogenization processes. In contrast, cold-seal high-pressure vessels are generally used to heat SMIs that have high internal pressures, although the homogenized SMIs can only be observed after quenching in this approach. Here we outline an alternative approach that uses a hydrothermal diamond anvil cell (HDAC) apparatus to homogenize SMIs. This is the only current method wherein phase changes in high-internal-pressure SMIs can be observed in situ during homogenization experiments, which represents an advantage over other conventional methods. Using an HDAC apparatus prevents high-internal-pressure SMIs from decrepitating during heating by elevating their external pressure, in addition to allowing in situ observations of SMIs. The type-V HDAC that is currently being used has a shorter distance between the sample chamber and the observation window than earlier types, potentially enabling continuous observation of the processes involved in heating and SMI homogenization through an objective lens with a long working distance. Homogenization experiments using HDAC require that a number of steps, including HDAC preparation, sample preparation, sample loading, preheating, and formal heating, be carefully followed. Homogenization experiments on SMIs within granite samples from the Jiajika pegmatite deposit (Sichuan, China) are best performed using an HDAC-based approach, because the elevated proper external pressure of these SMIs, combined with a short heating duration, helps to suppress material leakage and any reactions within the SMIs, in addition to allowing in situ observations during homogenization experiments. Furthermore, using the HDAC approach has other benefits: heating rates can be precisely controlled, wafer oxidization can be prevented, and samples can be subjected to in situ microbeam analysis. In summary, homogenization using HDAC provides more reliable results than those obtained using conventional heating equipment Future developments will include improvements to the quenching method and temperature controls for the HDAC apparatus, thereby improving the utility of this approach for SMI homogenization experiments.

Studies concerning the molecular complexation of Lippia sidoides essential oil in β-cyclodextrin by conventional and ultrasound assisted method

Lippia sidoides Cham. is an aromatic herb from Northeast of Brazil, popularly known as pepper-rosmarin. This plant contains an essential oil (EO) with high concentration of thymol and carvacrol; comparable of thyme oil. The presence of these and other bioactive compounds give this specie important antimicrobial, larvicidal, molluscicides, and antioxidant activities. When exposed to oxygen, light or heat, EOs can undergo irreversible alterations in their physicochemical properties. Microencapsulation can be applied to transform these substances into more stable materials (lower volatility and less susceptibility to oxidation) providing easy handling (solid form). Formation of inclusion complexes of EO in cyclodextrins has been reported as an efficient method to improve stability of their terpenoid compounds. There are several complexation methods, and the slurry method followed by water removal by filtration and evaporation or by other drying method (ex. freeze drying or spray drying) is one of the most commonly used. Since the slurry preparation and drying conditions are the key factor involved in the encapsulation efficiency, the aim of this work was to investigate the effects of ultrasound (ultrasound assisted complexation) in the efficiency of formation of inclusion complexes of L. sidoides EO in b-cyclodextrin (b-CD) compared with conventional homogenization technique. The ratio EO:b-CD studied were 1:10 and 2:10, and the solid content of the aqueous slurry set at 30%. The prepared slurries were spray dried at temperature of 160 °C, gas flow rate of 60 m3/h, feed composition flow rate of 4 g/min. EO content, thymol content, product mean diameter, moisture content, and process yield were the responses evaluated. The results showed that the use of ultrasound improved at least 1.2 times the complexation efficiency compared to the conventional homogenization method. The ratio EO:b-CD of 1:10 showed better performance with regard to the total EO retention.

A novel high-pressure precipitation tandem homogenization technology for drug nanocrystals production – a case study with ursodeoxycholic acid

To overcome the limitations of the conventional particle size reduction technologies, a novel combinative particle size reduction method for the effective production of homogeneous nanosuspensions was investigated. Ursodeoxycholic acid, a poorly soluble drug representative, was tried to prepare nanosuspension by homogenization technology and high-pressure precipitation tandem homogenization technology. It was shown that the combinative approach could significantly improve the particle size reduction effectiveness over conventional homogenization approach. The Box–Behnken design analysis for process optimization revealed that the acceptable UDCA-NS was obtained wherein the optimal values of A, B, C and D were 10%, 500 bar, 0.125 and 600 bar, respectively. SEM results demonstrated that no significant aggregation or crystals growth could be observed in the freeze-dried UDCA nanocrystals. The DSC and XRD results showed that UDCA remained in a crystalline state. Dissolution velocities of the freeze-dried UDCA-NS powder were distinctly superior compared to those of the crude powder and physical mixture. The high-pressure precipitation tandem homogenization technology can be a good choice for nanosuspension preparation of poorly soluble UDCA, due to high efficiency of particle size reduction.

Full-band exact homogenization of one-dimensional elastic metamaterials

Metamaterials extend the realm of materials’ properties by carefully designed structural inclusions. By targeting the extraction of effective properties from composite materials, homogenization theory plays an important role for metamaterials in their design and characterization. However, conventional homogenization methods are limited to the long wavelength limit. Here, we introduce an exact homogenization scheme valid for one-dimensional metamaterials over the full frequency band. In this scheme, with the aid of eigenstates’ characterization, a set of explicit formulas for effective mass density and effective elastic modulus are obtained by matching the surface responses properties of a metamaterial’s single structural unit with a piece of effectively homogenized material. In the frequency regimes beyond the conventional homogenization theory, new features, such as the imaginary parts of the effective parameters, have been found. Applying this scheme on a layered structure, the predicted transport properties and displacement fields from the effective parameters show excellent agreement with numerical simulations.

Effects of high pressure homogenisation of ice cream mix on the physical and structural properties of ice cream

This study investigated the effect of high pressure homogenisation (HPH) on the physical and structural properties of ice cream. Samples were produced from mixes differing in fat content (5% and 8%) and subjected to different homogenisation pressures (15/3 MPa and 97/3 MPa). Ice creams were compared for fat globule size distribution, overrun, melting behaviour, and hardness. No influence of HPH on fat structure destabilisation with respect to the conventional homogenisation (CH) was observed. The HPH ice cream samples with high fat content were characterised by the lowest overrun, the highest hardness and improved resistance to melting; the HPH ice creams with low fat content showed higher resistance to meltdown, but were not clearly differentiated for hardness with respect to the CH samples.