Influence of lipid content and dilution on properties and stability of nanostructured lipid carriers (NLCs) prepared from rambutan (Nephelium lappaceum L.) kernel fat and evaluation of their β-carotene loading capacity

Abstract

The effects of lipid content and dilution on the properties and stability of nanostructured lipid carriers (NLCs) prepared from rambutan (Nephelium lappaceum L.) kernel fat were investigated. The β-carotene-loading capacity of the NLCs was also evaluated. NLCs containing various lipid phase concentrations (5, 10, and 15?wt%) were prepared using Tween 80 as the emulsifier with a lipid to emulsifier weight ratio of 1:0.2. The results showed that an increase in the lipid content up to 15?wt% had no effect on the zeta-potential, particle size and polydispersity index but resulted in a higher particle density. All samples showed no phase separation during storage at 25?°C for 28?days; however, the relative recrystallization index (RRI) increased. Dilution of concentrated NLC (15?wt%) to a lower lipid content (5 and 10?wt%) produced no differences in the particle characteristics and stability during storage. NLCs loaded with β-carotene at different concentrations (0, 0.5, and 1?wt% of the lipid phase) exhibited desirable characteristics and had high encapsulation efficiency (～97%) over 28?days of storage. These results demonstrated that NLC prepared from rambutan kernel fat can be used to entrap lipophilic bioactive components which could be used as ingredients in functional food products.     

Systematic Identification of Analytical Indicators to Measure Soil Load on Plants for Safety Assessment Purposes

Abstract

Contaminants in soil can be transferred to humans and other biota when soil dust on plants is ingested as food. Measuring how much soil is on plants, in the absence of artificial tracers or contaminants, is difficult because of the very small amounts involved and the confounding effect of absorption of elements through roots. However, measurements of soil load are essential for assessment modelling. We compared the ability of several analysis strategies, involving naturally occurring elements, to predict the soil load on plants. Large samples of 12 vegetable and fruit crops were collected, along with corresponding soil samples. An independent measure of soil load on the crop samples was derived from a combination of gravimetric measurements, including loss on washing and the acid-insoluble ash content. The best agreement between the elemental-abundance and the gravimetric methods was for Sr in the plant acid-insoluble ash. Through a systematic process of elimination, we conclude that analyses of the acid-insoluble ash fraction of the plant samples for Al, Ba, Fe, Si, Sr and Ti are most reliable. If analyses are to be restricted to the full plant ash, then the choice of analytes is restricted to Al, Fe, Si and Ti. Soil loads in our study averaged 20 mg soil kg^?1 dry plant for leafy tissues and 2 mg soil kg^?1 for fruits, and washing decreased soil loads about 1.5 fold.     

Numerical-Analytic Solution of Boundary-Value Stress-Strain Problems for Rotating Anisotropic Cylinders

A numerical-analytical approach is proposed to solve boundary-value stress-strain problems for hollow inhomogeneous cylinders under centrifugal loading. Their elastic characteristics vary in both radial and circumferential directions. The governing system of ordinary differential equations is derived using Fourier series for stresses and displacements. It is solved by the discrete-orthogonalization method. Solutions to specific problems are exemplified __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 8, pp. 82–87, August 2005.     

横观各向同性材料椭圆片状裂纹问题的新方法

严格从三维横观各向同性材料弹性力学理论出发,用超奇异积分方程的方法对椭圆类片状裂纹问题进行了重新研究.超奇异积分方程中的未知位移间断近似地表示为基本密度函数与多项式之积,其中基本密度函数反映了椭圆片状裂纹前沿应力场的奇异性.椭圆片状裂纹在均布载荷作用下,通过巧妙地引入椭球坐标系,进一步得到了未知位移间断的封闭解.使用这些近似封闭解和应力强度的定义,精确地得到了裂纹前沿Ⅰ型、Ⅱ型和Ⅲ型应力强度因子以及电位移强度因子的表达式.该结果与现有精确解完全一致.     

DISSIPATIVITY BEHAVIOR OF IMPULSIVE FUNCTIONAL DIFFERENTIAL EQUATIONS

In this paper,we investigate the dissipativity behavior and give the range estimate for solutions of impulsive functional differential equations.Also,some criteria on asymptotical stability and exponential stability of the zero solution are obtained.     

Asymptotic Weighted-Periodicity of the Impulsive Parabolic Equation with Time Delay

The main aim of this paper is to investigate the effects of the impulse and time delay on a typeof parabolic equations.In view of the characteristics of the equation,a particular iteration scheme is adopted.The results show that Under certain conditions on the coefficients of the equation and the impulse,the solutionoscillates in a particular manner—called"asymptotic weighted-periodicity".     

BOUNDEDNESS IN TERMS OF TWO MEASURES FOR IMPULSIVE DISCRETE SYSTEMS

This paper concerns a class of impulsive discrete systems and offers sufficient conditions of boundedness in terms of two measures for such systems, by employing vector Lyapunov functions and a new comparison principle. The result obtained generalizes those in known literatures.     

Application of Special Nonsmooth Temporal Transformations to Linear and Nonlinear Systems under Discontinuous and Impulsive Excitation

Linear and nonlinear mechanical systems under periodic impulsive excitation are considered. Solutions of the differential equations of motion are represented in a special form which contains a standard pair of nonsmooth periodic functions and possesses a convenient structure. This form is also suitable in the case of excitation with a periodic series of discontinuities of the first kind (a stepwise excitation). The transformations are illustrated in a series of examples. An explicit form of analytical solutions has been obtained for periodic regimes. In the case of parametric impulsive excitation, it is shown that a nonequidistant distribution of the impulses with dipole-like temporal shifts may significantly effect the qualitative characteristics of the response. For example, the sequence of instability zones loses its different subsequences depending on the parameter of the shifts. It is shown that the method's applicability can be extended for nonperiodic regimes by involving the idea of averaging.     

脉冲中立型时滞抛物偏微分方程组的振动准则

考虑一类脉冲中立型时滞抛物偏微分方程组解的振动性,利用一阶脉冲时滞微分不等式获得了该类方程组在Robin,Dirichlet边值条件下所有解振动的若干充分条件.所得结果充分反映了脉冲和时滞在振动中的影响作用.     

单晶铜在动态加载下空洞增长的分子动力学研究

冲击载荷下延性材料的损伤是材料中微空洞的产生和长大演化的结果.利用分子动力学模拟 方法对延性金属单晶铜中单个空洞在动态加载下的演化发展进行了研究，得到了空洞增长过 程中的应力分布及空洞增长演化随冲击强度变化的规律.模拟结果表明，动态加载下的前期 压缩过程对后期拉伸应力场作用下的空洞增长演化特征有不可忽视的影响，微空洞增长的阈 值则与单晶实验中层裂强度随拉伸应力作用时间减少而增加的趋势相一致. 关键词： 层裂 分子动力学 动态加载 空洞