基于无机纳米粒子模板刻蚀的纳米阵列

阐述了利用不同的方法，如自组装、嵌段共聚物辅助等方法在基底表面形成一层均匀的无机材料纳米粒子掩模，以此作为模板进行刻蚀，可得到各种纳米图形和纳米结构。这一方法具有操作简单、成本低、可批量生产等优点，在纳米电子器件等领域具有广泛的应用前景。

基于Beowulf机群中改进粒子滤波的3D人体运动跟踪

针对标准的粒子滤波算法在视频三维人体运动跟踪中存在的计算量巨大、粒子退化、跟踪失效而无法同时满足跟踪精度和跟踪实时性要求的问题,提出了基于Beowulf机群中改进的粒子滤波新算法。新算法通过三维人体模型参数的自动初始化、粒子数目和模板的调整来实现跟踪失效的自动恢复,基于任务动态分配策略、低开销通信策略设计的Beowulf机群中的迁移式粒子滤波并行算法克服了粒子退化问题和提高了计算速度。实验结果显示:新方法有效地减轻了粒子退化和跟踪失效问题,降低了计算时间,提高了跟踪精度,能够同时满足三维人体运动跟踪精度和实时性的要求。

Preparation and functional characterization of tumor-targeted folic acid-chitosan conjugated nanoparticles loaded with mitoxantrone

Folic acid conjugated chitosan was prepared by cross-linking reaction with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride(EDC), and then used as a template to prepare folic acid-chitosan(FA-CS) conjugated nanoparticles and load mitoxantrone nanoparticles(FA-CSNP/MTX). Drug dissolution testing, CCK-8 method, and confocal microscopy were used to detect their controlled-release capability in different situations and the specific uptake by HONE1 cells. The experimental results show that the nanoparticles have uniform size distribution of 48-58 nm. The highest encapsulation rate of the particles on mitoxantrone hydrochloride(MTX) is(77.5±1.9)%, and the drug loading efficiency is(18.4±0.4)%. The sustained release effect, cell growth inhibition activity and targeting effect of the FA-CS/MTX nanoparticles are good in artificial gastric fluid and intestinal fluid. It is demonstrated that the FA-CSNP system is a potentially useful system for the targeted delivery of anticancer drug MTX.

Synthesis of magnetic core–shell structure Fe_3O_4@MCM-41 nanoparticle by vesicles in aqueous solutions

In this study, magnetic core–shell structure Fe3O4@MCM-41 nanoparticles were synthesized with vesicles as soft templates. In the preparation, Fe Cl2 and tetraethy orthosilicate(TEOS) were selected as Fe processor and Si precursor, respectively. Stable vesicles first formed in 0.03 mol·L-11:2 mixture of anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethyl ammonium bromide. Then, TEOS was added in the vesicle aqueous solution, leading to a highly dispersed solution. After high-temperature calcination, Fe3O4@MCM-41 nanoparticles were obtained. Their structure and morphology were characterized by Saturn Digisizer, transmission electron microscope and vibrating sample magneto-meter. The results indicate that the vesicles are spherical and their size could be tuned between 20 and 50 nm. The average grain diameter of synthesize magnetic core–shell Fe3O4@MCM-41 particles is 100–150 nm and most of them are in elliptical shape. The dispersion of magnetic particles is very good and magnetization values are up to 33.44 emu·g-1, which are superior to that of other Fe3O4 materials reported.

Tracking Submicron Particles in Microchannel Flow by Microscopic Holography

Three-dimensional tracking of submicron particles in flows in a micro-channel was carried out using in-line holographic microscopy.A fixed single 0.5 μm fluorescent particle was identified and isolated from dust particles or overlapped particle pair using the laser induced fluorescent(LIF) method.Then in-line microscopic holograms of the fixed single particle were obtained at different positions on the optical axis,i.e.the defocus distances.The holograms of the single particle were used as the model templates with the known defocus distances.The particles in the in-line microscopic holograms of flow in the microchannel were then identified and located to obtain their two-dimensional positions.The defocus distances of those particles were determined by matching each hologram pattern to one of the model templates obtained in the single particle test.Finally the three-dimensional position and velocity of each particle were obtained.

液相沉积法制备聚(苯乙烯-丙烯酸)／铁的氧化物纳微核壳粒子

描述了一种基于液相沉积法制备纳微核壳粒子的新方法,即以聚(苯乙烯-丙烯酸)乳胶粒子为模板,利用静电相互作用和液相沉积的方法,将氢氧化铁包覆在模板粒子表面,形成聚(苯乙烯-丙烯酸)/铁的氧化物核壳纳米复合粒子。通过TEM和SEM观察,Fe2O3晶粒在模板粒子表面生长并呈草莓状,壳层厚度均匀。该特殊结构有利于通过煅烧除核的方法获得硬质空心磁球。

Ice-templated preparation and sodium storage of ultrasmall SnO2 nanoparticles embedded in three- dimensional graphene

We report on the ice-templated preparation and sodium storage of ultrasmall SnO2 nanoparticles （3--4 nm） embedded in three-dimensional （3D） graphene （SnO2@3DG）. SnO2@3DG was fabricated by hydrothermal assembly with ice-templated 3DG and a tin source. The structure and morphology analyses showed that 3DG has an interconnected porous architecture with a large pore volume of 0.578 cm^3·g^-1 and a high surface area of 470.5 m^2·g^-1. In comparison, SnO2@3DG exhibited a pore volume of 0.321 cmg.g^-1 and a surface area of 237.7 m^2·g^-1 with a homogeneous distribution of ultrasmall SnO2 nanoparticles in a 3DG network. SnO2@3DG showed a discharge capacity of 1,155 mA-h·g^-1 in the initial cycle, a reversible capacity of 432 mA·h·g^-1 after 200 cycles at 100 mA·g^-1 （with capacity retention of 85.7% relative to that in the second cycle）, and a discharge capacity of 210 mAh·g^-1 at a high rate of 800 mA·g^-1 This is due to the high distribution of SnO2 nanoparticles in the 3DG network and the enhanced facilitation of electron/ion transport in the electrode.

Numerical study on explosion-induced fractures of reinforced concrete structure by beam-particle model

In the field of disaster prevention mitigation and protection engineering,it is important to identify the mechanical behaviors of reinforced concrete(RC)under explosive load by simulation.A three dimensional beam-particle model(BPM),which is suitable to simulate the fracture process of RC under explosive load,has been developed in the frame of discrete element method (DEM).In this model,only the elastic deformations of beams between concrete particles were considered.The matrix displacement method(MDM)was employed to describe the relationship between the deformation and forces of the beam.A fracture criterion expressed by stress was suggested to identify the state of the beam.A BPM for steel bar,which can simulate the deformation of steel bar under high loading rate,was also developed based on the Cowper-Symonds theory.A program has been coded using C++language.Experiments of RC slab under explosive load were carried out using the program.Good agreement was achieved between the experimental and simulated results.It is indicated that the proposed theoretical model can well simulate the fracture characteristics of RC slab under explosive load such as blasting pit formation,cracks extension, spallation formation,etc.

DNA template-synthesized silver nanoparticles:A new platform for high-performance fluorescent biosensing of biothiols

To develop the high-performance fluorescent bio-sensors, the metal nanoparticles were employed as nanoquenchers and at- tracted reasonable attention in the design of fluorescent biosensors. In this work, silver nanoparticles （AgNPs） were obtained via reduction of Ag＋ on FAM-labeled DNA template. For the tight binding between AgNPs and DNA, the tem- plate-synthesized AgNPs turned out high quenching efficiency and could be applied as super nanoquenchers to establish the biosensing platform for fluorescent detection. As an example, the template-synthesized DNA-AgNPs conjugates were em- ployed in sensing thiols. By forming S-Ag bonds, thiols interact intensely with AgNPs and replace the FAM-labeled DNA off from the surface of AgNPs, resulting in a fluorescence enhancement. Besides the advantages of lower background and higher signal-to-background ratio （S/B）, the conjugates present better stability, making them applicable in complicated biological fluids. To further evidence the feasibility of sensing thiols in real samples, the thiols in human urine were detected. The total amount of free thiols found in human urine was ranging from 229 μM to 302μM with the proposed sensor. To conclude the reliability, low content of Cys was added and the recovery was 98%-103%.

Monodisperse silver microspheres: A facile BSA template method

The spherical silver mirco/nano-particles with narrow size distributions were obtained by chemical reduction of silver ammonia solution with ascorbic acid as reducing agent and bovine serum albumin (BSA) as bio-template. The effects of the concentration of Ag+ ions, BSA and ammonia, reactive temperature on the silver morphology and particle sizes were investigated. SEM, TEM and XRD were employed to characterize the morphology and structures of the prepared silver mirco/nano-particles. The results show that the spherical silver particle with smooth surface and narrow size distributions can be obtained by controlling the concentration of Ag+ ions, BSA, reaction temperature, etc. By controlling the above parameters, the silver spherical mirco/nano-particles with particle sizes ranging from 0.2 to 2.3 m can be well prepared, which is expected to be used in manufacturing high performance electronic pastes.

Velocity Profiles between Two Baffles in a Horizontal Circular Tube

The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted heat.The baffles are also an important element inside the heat exchanger.Internal materials influence the flow pattern in the bed.The influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular tube.The velocity of the particles was measured before the baffle and between them in the test tube.Results show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front baffle.The flows circulate in the front and rear baffles.These flow profiles are related to the Reynolds number(Re) or the flow intensity.The velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front wall.Swirling flow was employed in this study,which was produced using tangential velocities at the inlet.At the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without swirl.However,velocities between two baffles are not much different from those without swirl.

Hetero-assembly of gold nanoparticles on a DNA origami template

Hetero-assembling of spherical building blocks with well-defined spatial distribution holds great significance in developing chiral nanostructures. Herein, a strategy for hetero-assembling of gold nanoparticles(Au NPs) was demonstrated using rigid bifacial DNA origami as templates. By tuning the sizes and the fixed location of Au NPs on DNA origami, right-handed and left-handed Au NPs nanostructures were respectively constructed. Gel electrophoresis indicated the formation of the DNA origami-Au NPs complex and transmission electron microscopy(TEM) visually displayed the arrangement of Au NPs in these two chiral structures. The spatial configuration and 3D geometry of Au NPs were further illustrated by the stereographic TEM with tilting angles from ?30° to 30°. This strategy provides a universal approach to construct the asymmetrical 3D geometries, which may have potential applications in biomimicking and nanophotonics.