Preparation, optimization, and characterization of chitosancoated solid lipid nanoparticles for ocular drug delivery

The present study aimed to develop and optimize chitosan coated solid lipid nanoparticles(chitosan-SLNs)encapsulated with methazolamide. Chitosan-SLNs were successfully prepared by a modified oil-in-water emulsification-solvent evaporation method with glyceryl monostearate as the solid lipid and phospholipid as the surfactant. Systematic screening of formulation factors was carried out. The optimized formula for preparation was screened by orthogonal design as well as Box-Behnken design with entrapment efficiency, particle size and zeta potential as the indexes. The entrapment efficiency of the optimized formulation(methazolamide-chitosan-SLNs)prepared was(58.5± 4.5)%,Particle size(247.7 ± 17.3) nm and zeta potential(33.5 ±3.9) mV. Transmission electron microscopy showed homogeneous spherical particles in the nanometer range. A prolonged methazolamide in vitro release profile was obtained in the optimized chitosan-SLNs suspension compared with methazolamide solution. No ocular damages were observed in the susceptibility test on albino rabbits. The results suggest that the combination of orthogonal design and Box-Behnken design is efficient and reliable in the optimization of nanocarriers, and chitosanSLNs is a potential carrier for ophthalmic administration.

Study on Mature Age of Individual Larix kaempferi

Based on the study of parse wood materials,the fitting empirical equation of tree growth was obtained,a function with tree growth as a variable and time as an independent variable.Through mathematical operations such as function derivation,the mature age of tree growth was obtained,and the obtained expected mature age for Larix kaempferi was 46 years.And the application,research directions and precautions of the mature ages were proposed.

Study on the Practical and Ideal Mature Age of Pinus densiflora

This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the practical and ideal mature ages of Pinus densiflora were 58 and 123.5 a, respectively. In addition, the application research direction and matters needing attention were proposed.

Study on Mature Age of An Individual Pinus thunbergii Parl

Through the study of parse wood materials, the fitting empirical equation of tree growth was obtained, a function with tree growth as a variable and time as an independent variable. Through mathematical operations such as function derivation, the mature age of tree growth was obtained. The obtained maturity age for the actual forest of Pinus thunbergii Parl was 51 a, and the ideal mature age was 66 a. And the application, research directions and precautions of the mature ages were proposed.

食物网关键种的判定及其对稳健性的影响

食物网关键种的定量判定方法不仅有助于揭示食物网中的物种关系,而且有利于对关键物种进行优先保护。本研究以包含49个物种的河流生态系统食物网为对象,计算网络中表征度性质的指标(点度中心度、中介中心度、紧密中心度),并根据指标对物种进行聚类,分析不同类物种影响食物网连接稳健性程度的差异,探讨不同节点去除方式下节点数量对食物网连接稳健性的影响。结果发现,聚类将食物网中物种分成三类。I类物种具有相对较高的点度中心度、中介中心度、紧密中心度;II类物种具有相对更低的点度中心度、中介中心度、紧密中心度;III类物种的点度中心度、中介中心度、紧密中心度介于前两者之间。I类物种处于更为重要的地位,可认为是关键种。本研究为如何判定关键种贡献了新的思路。另外,升序去除方式下,连接稳健性呈降低趋势;降序去除与随机去除方式下,连接稳健性在持续降低后又有小幅度增加,这表明去除方式对食物网连接稳健性有影响。三种去除方式下,食物网连接稳健性发生显著变化对应着几乎相同的去除节点数量,表明关键种在维持食物网稳健性方面发挥着重要作用。