磷酸超声提取大气颗粒物中砷的多种形态

以H<,3>PO<,4> 为提取剂,利用高效液相色谱与氢化物发生原子荧光光谱联用(HPLC-HG-AFS)实现了大气颗粒物中砷形态的温和提取测定,并通过标准样品的形态加标实验确定了最佳提取方法.在优化的色谱及光谱条件下,As(Ⅲ),As(Ⅴ),MMA(甲基胂酸)和DMA(二甲基胂酸)均可达基线分离,其方法检出限分别为1...     

Dynamics of two elliptical particles sedimentation in a vertical channel: chaotic state

The LB-DF/FD method derived from the Lattice Boltzmann Method and direct forcing/fictitious domain method is used to numerically investigate the dynamics and interaction of two elliptical particles settling in an infinitely long channel. One particle (EP0) is initially kept horizontal (major axis perpendicular to sedimentation) for all simulations while the other's (EP1) orientation is varied. It is found that if EP1strays away from horizontality, the particles undergo transitions from a steady state to reach a chaotic state. Furthermore, there are two distinct chaotic states for the particle motion when EP1 orientation is varied, in which a turning point is observed to distinguish the two states.     

Topical application of zein-silk sericin nanoparticles loaded with curcumin for improved therapy of dermatitis

Atopic dermatitis is characterized by leukocyte migration into the skin dermis and typically driven by excessive chemokine production at the site of inflammation. Conventional topical formulations such as gels, creams, and ointments are insufficient for this treatment because of low penetration of drug molecules into the targeted skin tissues. Herein, using a simple, green, sustainable strategy, we have developed novel primary zein nanoparticles embedded in curcumin (Cur) and coated with silk sericin (ZHSCs) for the topical delivery of Cur to penetrate into the dermis and exercise anti-dermatitis effects on the lesion with minimal side-effects. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that ZHSCs facilitate the penetration of Cur across the epidermis layer of skin to reach deep-seated sites. Notably, ZHSCs = 1:0.25 (zein-to-silk sericin mass ratios of 1:0.25) markedly elevated the skin permeability and cumulative turnover of Cur transferred, which were provided a greater than a 3.8-fold increase relative to free Cur. The special nanoparticles of ZHS = 1:0.25 possessed the deepest localization depth and experience a transition of the particle structure and core-shell separation after penetrating into the dermis of skin. In a cell model of dermatitis induced by tumor necrosis factor α/interferon γ co-stimulation, compared with free Cur, Cur-loaded ZHS nanoparticles down-regulated the generation of inflammatory cytokines and chemokines in keratinocytes through suppression of the nuclear translocation of NF-κBp65 and hence exerted an anti-dermatitis effect. This strategy may provide new avenues and direction for the demanding issues of valid topical delivery systems.     

Accumulation of Particles and Formation of a Dissipative Structure in a Nonequilibrium Bath

The standard textbooks contain good explanations of how and why equilibrium thermodynamics emerges in a reservoir with particles that are subjected to Gaussian noise. However, in systems that convert or transport energy, the noise is often not Gaussian. Instead, displacements exhibit an α-stable distribution. Such noise is commonly called Lévy noise. With such noise, we see a thermodynamics that deviates from what traditional equilibrium theory stipulates. In addition, with particles that can propel themselves, so-called active particles, we find that the rules of equilibrium thermodynamics no longer apply. No general nonequilibrium thermodynamic theory is available and understanding is often ad hoc. We study a system with overdamped particles that are subjected to Lévy noise. We pick a system with a geometry that leads to concise formulae to describe the accumulation of particles in a cavity. The nonhomogeneous distribution of particles can be seen as a dissipative structure, i.e., a lower-entropy steady state that allows for throughput of energy and concurrent production of entropy. After the mechanism that maintains nonequilibrium is switched off, the relaxation back to homogeneity represents an increase in entropy and a decrease of free energy. For our setup we can analytically connect the nonequilibrium noise and active particle behavior to entropy decrease and energy buildup with simple and intuitive formulae.     

大气气溶胶粒子光吸收系数的测量

 采用核孔过滤膜累积气溶胶粒子的方法设计了气溶胶粒子光吸收系数的测量系统。该系统由双光路组成,可以减小光路损耗和电路噪声带来的各种测量误差。同时，具有体积小、光路易于调节、可进行实时测量、定标容易等特点。用200和400nm孔径的过滤膜，分别测量了实验室内大气气溶胶粒子对不同波长激光的吸收系数。随着累积时间的增加，系统的测量精度也不断的提高，在累积时间为900s时，系统测量误差为9.849×10^-6/m。     

On the Boltzmann Equation for Fermi–Dirac Particles with Very Soft Potentials: Averaging Compactness of Weak Solutions

The paper considers macroscopic behavior of a Fermi–Dirac particle system. We prove the L ¹-compactness of velocity averages of weak solutions of the Boltzmann equation for Fermi–Dirac particles in a periodic box with the collision kernel b(cos θ)|ρ−ρ _*|^γ, which corresponds to very soft potentials: −5 < γ ≤ −3 with a weak angular cutoff: ∫₀ ^π b(cos θ)sin ³θ dθ < ∞. Our proof for the averaging compactness is based on the entropy inequality, Hausdorff–Young inequality, the L ^∞-bounds of the solutions, and a specific property of the value-range of the exponent γ. Once such an averaging compactness is proven, the proof of the existence of weak solutions will be relatively easy.     

10MW串级脉冲发电机的理论、设计、实验及应用研究

 脉冲发电机具有小型、机动、灵活、可靠、寿命长等特点, 作为高功率固体激光器和加速器电源是一新的技术路线。比较了各种类型脉冲电源的性能指标,解释了旋转磁通压缩和串级原理,提出串级脉冲发电机的自激、偏极与双机同壳概念,给出电机的设计公式,10MW串级脉冲发电机的设计、实验及在强激光与粒子束领域中的潜在应用。     

基于不规则衍射理论的冰晶粒子的光散射研究(英文)

在不规则衍射理论的基础上,分析了从可见光到近红外波段冰晶粒子的光散射特性。计算了粒子尺度为20μm,50μm,80μm的五种典型冰晶粒子的消光效率因子和吸收效率因子。最后,为了评估不规则衍射理论的精确性,与有限时域差分法和几何光学法进行了比较。     

基质折射率对金属粒子散射特性的影响

基于Mie散射理论,给出了金属粒子的散射、吸收和消光截面以及散射场强度的计算公式,并计算了三种金属(金、银、铜)粒子在不同折射率基质中的光学截面和散射强度.结果表明,在近红外区,这三种金属粒子的散射行为随基质折射率的变化规律相同,折射率越大散射特性越明显.     

Preliminary study on aerosol particle addition calibration method for on-line quantitative analysis of airborne radioactive particles with ICP-MS

An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between ¹⁵⁹?Tb and ¹⁷⁴?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of ¹⁵⁹?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min^?1 to 100?mL?min^?1, the ratio of ¹⁵⁹?Tb ion count to ¹⁷⁴?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of ¹⁵⁹?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG.