带粒子释放和速度限制的粒子群算法

针对粒子群算法存在的收敛性与多样性之间的矛盾,在惯性权重线性递减的基础上,提出了带粒子释放和速度限制的算法。用粒子释放来增加种群多样性,引导算法跳出局部最优;用速度限制来促使释放后的粒子快速收敛到全局最优,进而平衡粒子的释放速度和收敛速度,保证算法的收敛。通过五个测试函数的实验,证实了粒子释放和速度限制的综合应用显著提高了算法的寻优能力和收敛精度。

粒子释放与速度动态变化的改进粒子群算法

本文为了改善标准粒子群算法常见的收敛较慢、搜索易陷入局部最优、搜索精度较低的缺点,提出粒子释放与速度动态变化的改进粒子群算法。粒子释放的目的是增加粒子的种群多样性,促使陷入局部最优的粒子跳出局部最优,粒子速度动态度变化是来引导释放后的粒子再次快速收敛到全局最优,避免粒子释放后造成的收敛变慢或者结果发散。算法改善之后使用三种测试函数对新算法进行验证,并与其他改进型粒子群算法优化结果进行了对比,结果表明改进策略在改善标准粒子群算法收敛慢、易陷入局部最优、搜索精度低等缺点的可行性与有效性。

粒子群优化算法的改进

针对粒子群优化算法搜索精度不高、对高维函数优化性能不佳的问题,提出一种改进的粒子群优化算法。以递增方式对粒子进行释放增强可利用的种群信息,通过释放粒子引导极值变化加强算法的运算效率。实验结果表明,与其他算法相比,改进算法具有更强的寻优能力和搜索精度,且适于高维复杂函数的优化。

不同环境介质轮胎微塑料老化及小粒径微粒释放特征

为了探究轮胎微塑料在不同环境介质中的老化和小粒径微粒释放特征,于实验室条件下模拟了汽车和电动自行车两种不同的轮胎微塑料在干燥和水环境中的老化过程.结果表明,轮胎微塑料经过30 d的紫外光照后会发生一定程度的老化,具体表现为表面变得粗糙,出现裂纹和剥落等现象.通过傅里叶红外光谱得知,其表面羰基指数也有所上升.此外,轮胎微塑料在紫外光照和水力作用的影响下会释放大量的亚微米级小粒子,水环境中的汽车轮胎微塑料在光照条件下第30 d时每mL溶液中释放粒子数量达到了69480万个,其中粒径小于1μm的有69460万个,是黑暗条件下的100倍左右.研究表明,水环境中的轮胎微塑料在光照条件下更易发生老化并释放更多的小粒子,且汽车轮胎微塑料较电动自行车轮胎微塑料释放的小粒子更多,具有潜在的生态环境风险.

超高速氦气系统经皮微球给药研究

目的 研究微球的粒子大小和超高速氦气气流的压力对释放固体微球经皮给药吸收过程的影响。方法利用氦气的超高速流体通过对固体粒子进行加速的方法 ,将药物粉末透过角质层释放到表皮和真皮表面 ,将固体药物粉末通过皮肤释放到体内。结果 药物导入率依赖于超高速氦气气流的压力和微球的粒子大小 ,且生物利用度和最高血中浓度也依赖于超高速氦气气流压力的影响。结论 本系统可用于固体药物粉末、多肽类药物。

自动划分区间中基于自适应攻击特征定位算法

网络攻击检测系统的检测性能与攻击特征的性质具有较强的关联性。网络中的攻击特征存在强随机性高复杂性的特点,传统算法在特征寻优过程中由于受到复杂性的影响,很难控制算法中的寻优速度,很容易造成在复杂环境下的算法不收敛,影响检测准确性。为提高准确性,提出了一种带粒子释放和速度约束的入侵检测算法,算法对采集得到的攻击特征自动划分区间,采用粒子释放控制的方法增强种群的多样性,避免算法出现局部最优现象,并采用速度约束释放后粒子收敛速度,优化检测入侵特征过程的寻优性能,获取准确的攻击特征。实验结果表明,粒子释放和速度约束方法具备较高的寻优性能以及收敛能力,是一种有效的攻击特征寻优算法。

pH-responsive mesoporous silica nanoparticles employed in controlled drug delivery systems for cancer treatment

In the fight against cancer, controlled drug delivery systems have emerged to enhance the therapeutic efficacy and safety of anti-cancer drugs. Among these systems, mesoporous silica nanoparticles （MSNs） with a functional surface possess obvious advantages and were thus rapidly developed for cancer treatment. Many stimuli-responsive materials, such as nanopartides, polymers, and inorganic materials, have been applied as caps and gatekeepers to control drug release from MSNs. This review presents an overview of the recent progress in the production of pH-responsive MSNs based on the pH gradient between normal tissues and the tumor microenvironment. Four main categories of gatekeepers can respond to acidic conditions. These categories will be described in detail.

The Ratio of Particle Flux of the Hydrogen to Carbon on Divertor Configuration in HL-2A Tokamak

Interactions of plasma with the walls lead to particle release by various mechanisms and the amount of impurities in the plasma core limits the performance of the device. It is very important to get the particle fluxes for understanding the releasing mechanisms of impurities. The spectroscopic measurements to determine the impurity influx from localized surfaces in tokamak plasma is described in detail in Ref. Determined the origin of the chromium influxes by this method in ASDEX during ICRF heating were reported in Ref.

SYNTHESIS OF BOWL-LIKE PARTICLES BY EMULSION POLYMERIZATION AND RELEASE BEHAVIOR OF SOLVENT FROM THE PARTICLES

Poly(styrene-glycidyl methacrylate) particles having bowl-shaped hollow structures were synthesized by swollen seed emulsion polymerization. The PS emulsion synthesized through soap-free emulsion polymerization was swollen by toluene, and then the mixture of second monomers was added under polymerization condition. So a thin shell of poly(styrene-glycidyl methacrylate) cross-linked by triethylene glycol diacrylate was formed around the swollen PS particle. The bowl-shaped particles were obtained after the collapsing of the thin shell when the toluene emanated from the particles, but the shapes were effected by the degrees of cross-linking. The shape of the particles was observed by SEM. The release behavior of solvent from the particles was examined by TG.

Nanoparticle mediated controlled delivery of dual growth factors

Peripheral nerve functional recovery after nerve injury generally requires multiple growth factors by synergistic effect.However,the optical combination of multiple synergistic growth factors for axonal regeneration has been scarcely considered up to now.Meanwhile,the use of growth factors in promoting nerve regeneration was limited by its short biological half-life in vivo,its vulnerability to structure disruption or hydrolyzation,leading to loss of bioactivity.Herein,a novel polymeric nanoparticle delivery system composed of heparin andε-poly-L-lysine(PL)was prepared for control release of nerve growth factor(NGF)and basic fibroblast growth factor(bFGF).The nanoparticles were synthesized by polyelectrolyte complexation in aqueous solution at room temperature,followed by cross-linking with biological genipin.The obtained nanoparticles had a spherical shape,with a mean diameter of about 246 nm,and high growth factors encapsulation efficiency as well as good stability.NGF and bFGF were encapsulated in the nanoparticles and showed a continuous and slow release behavior in vitro.The bioactivities of the released growth factors were evaluated,and exhibited the synergistic effect.The controlled release of the dual synergistic growth factors would improve the treatment of peripheral nerve injury to mimic the natural cellular microenvironments.

Effects of sediment physical properties on the phosphorus release in aquatic environment

Particle size, porosity, and the initial phosphorus concentration in sediments are the main factors affecting phosphorus release flux through the sediment-water interface. Sediments can be physically divided to muddy and sandy matters, and the adsorption-desorption capacity of sediment with phosphorus depends on particle size. According to phosphorus adsorption-desorption experiments, phosphorus sorption capacity of the sediment decreases with the increase of particle dimension. But among the size-similar particles, sediment with a bigger particle size has the larger initial phosphorus release rate. In terms of muddy and sandy sediments, there are inversely proportional relationships between the release rate and the flux. Due to the contact of surface sediment and the overlying water, the release flux from the sediment is either from direct desorption of surface sediment layer or from the diffusion of pore water in the sediment layer, which is mainly determined by sediment particle size and porosity. Generally, static phosphorus release process may include two stages: the first is the initial release. As for coarse particles, phosphorus is desorbed from surface sediment. And for fine particles, phosphorus concentration in water often decreases, mainly from pore water by the molecular diffusion. During the second stage, pore water flows faster in coarse sediment, and phosphorus is easy to desorb from the surface of the particles as diffusion dominates. For the smaller liquid-solid ratio of fine particles and the larger amount of phosphorus adsorption, the release flux from pore water due to diffusion is very small with longer sorption duration.

Surface-modulated and thermoresponsive polyphosphoester nanoparticles for enhanced intracellular drug delivery

The chemical structure of end groups influenced the phase transition temperature of thermoresponsive polymers. We demonstrated a strategy for the preparation of the pH/thermo-responsive polymeric nanoparticles via subtle modification of end groups of thermoresponsive polymer segments with a carboxyl group and revealed its potential application for enhanced intracellular drug delivery. By developing a polymeric nanoparticle composed of poly(aliphatic ester) as the inner core and thermoresponsive polyphosphoester as the outer shell, we showed that end groups of thermoresponsive polyphosphoester segments modified by carboxyl groups exhibited a pH/thermo-responsive behavior due to the hydrophilic to hydrophobic transitions of the end groups in response to the pH. Moreover, by encapsulating doxorubicin into the hydrophobic core of such pH/thermo-responsive polymer nanoparticles, their intracellular delivery and cytotoxicity to wild-type and drug-resistant tumor cells were significantly enhanced through the phase-transition-dependent drug release that was triggered by endosomal/lysosomal pH. This novel strategy and the multi-responsive polymer nanoparticles achieved by the subtle chain-terminal modification of thermoresponsive polymers provide a smart platform for biomedical applications.

An indicator-guided photo-controlled drug delivery system based on mesoporous silica/gold nanocomposites

A mesoporous silica/gold （MSN/Au） nanocomposite was designed for photo- controlled drug delivery targeted specifically at tumor cells. The MSN/Au nanocomposite was composed of MSN-based drug carriers and gold nanoparticle （AuNP）-based indicators. While the MSN-based drug carrier was a mesoporous silica nanoparticle immobilized with photo-switchable azobenzene （Azo） moieties, the AuNP-based indicator was a fluorescence-quenched AuNP modified with a matrix metalloproteinase （MMP） substrate and poly（ethylene glycol）. The two kinds of nanoparticles were connected by an α,β cyclodextrin （α,β CD） dimer ＂bridge.＂ In vitro studies demonstrated that the nanocomposite specifically interacted with tumor sites overexpressing MMP-2, which enabled guidance of the subsequent UV light irradiation for releasing entrapped drugs. Through integration of the AuNP-based indicator and the MSN-based drug carrier, the MSN/Au nanocomposite could precisely localize the released drug to tumor sites, thereby significantly improving therapeutic efficacy.