Optimization of the Conditions of Solid Lipid Nanoparticles (SLN) Synthesis

Solid lipid nanoparticles (SLNs) have been synthesized as potential drug delivery systems. They are classified as solid lipid nanocarriers that can successfully carry both hydrophilic and hydrophobic drugs. SLNs are based on a biocompatible lipid matrix that is enzymatically degraded into natural components found in the human body. Solid lipid nanoparticles are suitable for the incorporation of hydrophobic active ingredients such as curcumin. The study included the optimization of lipid nanoparticle composition, incorporation of the active compound (curcumin), a stability evaluation of the obtained nanocarriers and characterization of their lipid matrix. Through process optimization, a dispersion of solid lipid nanoparticles (solid lipid:surfactant—2:1.25 weight ratio) predisposed to the incorporation of curcumin was developed. The encapsulation efficiency of the active ingredient was determined to be 99.80%. In stability studies, it was found that the most suitable conditions for conducting high-pressure homogenization are 300 bar pressure, three cycles and a closed-loop system. This yields the required values of the physicochemical parameters (a particle size within a 200–450 nm range; a polydispersity index of <30%; and a zeta potential of about |±30 mV|). In this work, closed-loop high-pressure homogenization was used for the first time and compared to the currently preferred open-loop method.     

The skin effect in vibrating systems with many concentrated masses

We address the asymptotic behaviour of the vibrations of a body occupying a domain $\Omega\subset\mathbb{R}^n, n=2,3$. The density, which depends on a small parameter $\varepsilon$\nopagenumbers\end , is of the order $O(1)$\nopagenumbers\end out of certain regions where it is $O(\varepsilon^{‐m})$\nopagenumbers\end with $m>2$\nopagenumbers\end . These regions, the concentrated masses with diameter $O(\varepsilon)$\nopagenumbers\end , are located near the boundary, at mutual distances $O(\eta)$\nopagenumbers\end , with $\eta=\eta(\varepsilon)\rightarrow 0$\nopagenumbers\end . We impose Dirichlet (resp. Neumann) conditions at the points of $\partial\Omega$\nopagenumbers\end in contact with (resp. out of) the masses. We look at the asymptotic behaviour, as $\varepsilon\rightarrow 0$\nopagenumbers\end , of the eigenvalues of order $O(1)$\nopagenumbers\end , the high frequencies, of the corresponding eigenvalue problem. We show that they accumulate on the whole positive real axis and characterize those giving rise to global vibrations of the whole system. We use the fact that the corresponding eigenfunctions, microscopically, present a skin effect in the concentrated masses. Copyright © 2001 John Wiley & Sons, Ltd.     

Ultrasound stabilization of raw milk: Microbial and enzymatic inactivation,physicochemical properties and kinetic stability

The aim of this study was to evaluate the effects of non-thermal and thermal high-intensity ultrasound (HIUS) treatment on the microbial and enzymatic inactivation, physicochemical properties, and kinetic stability of the raw milk by applying different energy densities (1, 3, 5, and 7 kJ/mL). Two HIUS treatments were evaluated based on different nominal powers, named HIUS-A and HIUS-B, using 100 W and 475 W, respectively. HIUS-A treatment was non-thermal processing while HIUS-B was a thermal treatment only for the energy densities of 5 and 7 kJ/mL since the final temperature was above 70 °C. The HIUS-B treatment showed to be more efficient. Log reductions up to 3.9 cycles of aerobic mesophilic heterotrophic bacteria (AMHB) were achieved. Significant reductions of the fat globule size, with diameters lower than 1 µm, better color parameters, and kinetic stability during the storage were observed. Also, HIUS-B treatment inactivated the alkaline phosphatase and lactoperoxidase. The HIUS-B treatment at 3 kJ/mL worked below 57 °C being considered a border temperature since it did not cause unwanted physicochemical effects. Furthermore, a microbial inactivation of 1.8 ± 0.1 log cycles of AMHB was observed. A proper inactivation of only the Alkaline phosphatase and a significant reduction of the fat globules sizes, which kept the milk kinetically stable during storage was achieved.     

Homogenization process caused by competition between phase separation and ester‐interchange reactions in immiscible polyester blends: A Monte Carlo simulation

The homogenization process caused by competition between phase separation and ester‐interchange reactions in immiscible polyester blends was investigated via the Monte Carlo simulation method. Phase separation and ester‐interchange reactions were performed simultaneously with the one‐site bond fluctuation model on a homogeneous blend of immiscible polyesters. Three different values of the repulsive pair‐interaction energy (E_AB) between segments A and B and two trial ratios of phase separation to ester‐interchange reactions at a given E_AB were introduced to examine the competition between them. Phase separation was monitored by the calculation of the collective structure factor, and copolymerization was traced by the calculation of the degree of randomness (DR). In all cases, as the homogenization proceeded, the maximum intensity of the collective structure factor initially increased, reached a maximum, and finally decreased, whereas the peak position where the structure factor had a maximum shifted downward in the early stage and then remained unchanged after the intensity of the collective structure factor reached the maximum. This indicates that during the homogenization process, the domain size did not change significantly after phase‐separated structures were developed distinctly. In this simulation, phase‐separated structures were traced until the DR was above 0.8. This result indicates that homogenization can be accomplished via homogeneous ester‐interchange reactions over most of the polyester chains because copolyesters resulting from ester‐interchange reactions do not act as an efficient compatibilizer. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 590–598, 2000     

Quantum dynamics of an impurity-doped Bose-Einstein condensate system

We study the quantum dynamics of an impurity-doped Bose–Einstein condensate (BEC) system. We show how to generate the macroscopic quantum superposition states (MQSSs) of the BEC by the use of projective measurements on impurity atoms. It is found that the nonclassicality of MQSSs can be manipulated by changing the number of the impurities and their interaction with the BEC. It is shown that the BEC matter-wave field exhibits a collapse and revival phenomenon which reveals the quantum nature of the BEC matter-wave field. We investigate the micro-macro entanglement between the impurities and the BEC, and find enhancement of the micro-macro entanglement induced by the initial quantum coherence of the impurity atoms.     

Optimal internal architectures of femoral bone based on relaxation by homogenization and isotropic material design

The influence of the loading conditions on the trabecular architecture of a femur is investigated by using topology optimization methods. The response of the bone to physiological loads results in changes of the internal architecture of bone, reflected by a modification of internal effective density and mechanical properties. The homogenization based optimization model is developed for predicting optimal bone density distribution, wherein bone tissue is assumed to be a composite material consisting of a mixture of material and void. The homogenization scheme treats the geometric parameters of the microstructures and their orientation as design variables and homogenizes the properties in that microstructure, which is generally anisotropic. The penalization of the optimal material density then leads to a classical optimal structure which consists of regions with bone material and regions without bone material. The IMD (Isotropic Material Design) approach is next applied to determine the optimal elasticity tensor in terms of the bulk and shear moduli for the present loading applied to the femoral bone sample. IMD is able to provide both the external shape and topology together with the optimal layout of the isotropic moduli. Both topology optimization methods appear to be complementary. Simulations of the internal bone architecture of the human proximal femur results in a density distribution pattern with good consistency with that of the real bone.     

Moment bounds on the corrector of stochastic homogenization of non-symmetric elliptic finite difference equations

We consider the corrector equation from the stochastic homogenization of uniformly elliptic finite difference equations with random, possibly non symmetric coe?cients. Under the assumption that the coe?cients are stationary and ergodic in the quantitative form of a logarithmic Sobolev inequality (LSI), we obtain optimal bounds on the corrector and its gradient in dimensions d≥2. Similar estimates have recently been obtained in the special case of diagonal coe?cients making extensive use of the maximum principle and scalar techniques. Our new method only invokes arguments that are also available for elliptic systems and does not use the maximum principle. In particular, our proof relies on the LSI to quantify ergodicity and on regularity estimates on the derivative of the discrete Green’s function in weighted spaces. In the critical case d = 2, our argument for the estimate on the gradient of the elliptic Green’s function uses a Calderón–Zygmund estimate in discrete weighted spaces, which we state and prove. As applications, we provide a quantitative two-scale expansion and a quantitative approximation of the homogenized coe?cients.     

Effects of natural antioxidants and high-energy fabrication methods on physical properties and oxidative stability of flaxseed oil-in-water nanoemulsions

The effects of high-energy fabrication methods, namely high-pressure homogenization (HPH) and ultrasonication (US), on physicochemical properties of flaxseed oil-in-water nanoemulsions (FNEs) containing clove essential oil (CEO) and/or pomegranate peel extract (PPE) were studied during storage at 4 and 25 °C. Nanoemulsions with relatively similar average droplet size were prepared by HPH and/or US. An increase in droplet size was observed over time. Lower storage temperature and fabrication by US increased Ostwald ripening rate. Higher storage temperature and fabrication by US decreased the centrifugal stability of nanoemulsions. CEO revealed better antioxidant properties than PPE. The oxidative stability was evaluated by determining secondary oxidation products, and fatty acids profile. The absence of antioxidant, fabrication by US, and higher storage temperature decreased the oxidative stability of nanoemulsions. The results of this study might be helpful in controlling the oxidation of FNEs during long-term storage and in designing functional foods and beverages.     

Anti-solvent precipitation for the preparation of nobiletin nano-particles under ultrasonication-cis/reverse homogenization

In order to address the issue of nobiletin's limited bioavailability, nobiletin nanoparticles (NNP) were created for the first time in this research employing an anti-solvent under ultrasonication-cis/reverse homogenization. Dimethyl sulfoxide (DMSO) was used as the solvent and deionized water as the anti-solvent to create the nobiletin solution. The optimal surfactant dose of surfactant dose of 0.43%; an ultrasonic period of 8.1 min, ultrasonic at a temperature of 64 °C and a solution concentration of 8.33 mg/mL, the method was optimized to obtain the minimum NNP diameter of 199.89 ± 0.02 nm. A dual optimization process of response surface PBD and BBD was used to minimize the size of HNP particles. Additionally, scanning electron microscopy revealed that the specific surface area of the NNP dramatically increased with the reduction of NNP particle size, and dissolving studies indicated the solubility and dissolution studies showed that NNP had substantially greater solubility and dissolution rates than raw nobiletin per unit time; as a result, the NNP produced by anti-solvent precipitation with a twofold homogenization system supported by ultrasound had a realistic potential for growth.