极性晶体中表面极化子的温度效应

有不少的极性晶体,电子与体纵光学声子的耦合弱,但与表面光学声予的耦合强.本文讨论电子和体纵光学声子耦合弱,与表面光学声子耦合强时对表面极化子的温度特性的影响,用线性组合算符法研究表面极化子的振动频率、诱生势和有效质量的温度依赖性.对AgBr晶体进行了数值计算,结果表明极化子的振动频率,诱生势和有效质量随温度的升高而减小.     

威布尔分布恒定——步进应力加速寿命试验可靠性统计分析方法及软件包

本文利用一个应力水平的恒定加速和一组步进加速寿命试验,给出使用寿命服从威布尔分布的机电产品的可靠性统计分析及计算软件包。     

Synthesis of HgSe quantum dots through templates controlling and gas–liquid transport with emulsion liquid membrane system

A new synthetic method of HgSe quantum dots has been investigated through template controlling with emulsion liquid membrane system. The membrane system consists of kerosene as solvent, span80 as surfactant, N7301 as carrier, and HgCl₂ solution as internal-aqueous phase containing template of different concentrations, and uses gas–liquid transport on interface of external phase. Its optimum condition is as follows, kerosene:span80:N7301 = 74:6:20, Roi=1:1. While using inorganic KI as the template and adjusting HgCl₂ concentrations (keeping KI/HgCl₂ = 10), transmission electron microscope shows that HgSe quantum dots of different sizes can be obtained respectively, X-ray diffraction (XRD) reveals that the products have a cubic structure. The research has shown that quantum confinement effect of these HgSe quantum dots (2–3 nm) have inverted band structure (HgSe bulk) increase their effective bandgap giving rise to infrared (IR) luminescence. Its forming process is also inferred.     

Crystallization behaviors of n-octadecane in confined space: crossover of rotator phase from transient to metastable induced by surface freezing

In this paper, the confined crystallization and phase transition behaviors of n-octadecane in microcapsules with a diameter of about 3 microm were studied with the combination of differential scanning calorimetry (DSC), temperature dependent Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The main discovery is that the microencapsulated n-octadecane crystallizes into a stable triclinic phase via a mestastable rotator phase (R I), which emerges as a transient state for the bulk n-octadecane and is difficult to be detected by the commonly used characterization methods. As evident from the DSC measurement, a surface freezing monolayer, which is formed at the interface between the microcapsule inner wall and n-octadecane, induces the crossover of the R I from transient to metastable. We argue that the existence of the surface freezing monolayer decreases the nucleating potential barrier of the R I phase, and consequently the lower relative nucleation barrier in the confined geometry turns the transient R I phase into a metastable one.     

Current reversal in a two-noise ratchet

We consider a model (Lengyel-Epstein) reaction-diffusion system under spatial parametric modulation and demonstrate the effect of resonance shift of the Hopf-Turing boundary. A systematic perturbative and numerical analysis shows that this shift may induce spatial inhomogeneity on an homogeneous stable state resulting in pattern formation.     

Precise nanomedicine for intelligent therapy of cancer

Precise nanomedicine has been extensively explored for efficient cancer imaging and targeted cancer therapy, as evidenced by a few breakthroughs in their preclinical and clinical explorations. Here, we demonstrate the recent advances of intelligent cancer nanomedicine, and discuss the comprehensive understanding of their structure-function relationship for smart and efficient cancer nanomedicine including various imaging and therapeutic applications, as well as nanotoxicity. In particular, a few emerging strategies that have advanced cancer nanomedicine are also highlighted as the emerging focus such as tumor imprisonment, supramolecular chemotherapy, and DNA nanorobot. The challenge and outlook of some scientific and engineering issues are also discussed in future development. We wish to highlight these new progress of precise nanomedicine with the ultimate goal to inspire more successful explorations of intelligent nanoparticles for future clinical translations.     

3种苄基取代的β—环糊精作为气相色谱固定相的研究

对３种苄基化β－环糊精固定相进行了研究，考察了它们的色谱性能及对各种位置异构体的分离，研究了柱温对保留行为的影响，并讨论了环糊精保留的机理。     

Hugely enhanced flame retardancy and smoke suppression properties of UHMWPE composites with silicone‐coated expandable graphite

In this paper, silicone‐coated intumescent flame retardants was prepared by an efficient and simple approach, aiming at enhancing the flame‐retardant efficiency and smoke suppression properties. The surface of expandable graphite (EG) was treated prior to the coverage of nonflammable silicone. The resultant silicone‐modified EG hybrid (SEG) was combined with ammonium polyphosphate (APP) and applied as a flame‐retardant and smoke‐suppressant for ultrahigh molecular weight polyethylene (UHMWPE). Compared with UHMWPE/APP/EG (with 15 wt% APP/EG), UHMWPE/APP/SEG (with 15 wt% APP/SEG) gives decrement by 18.5% in the peaks of the heat release rate, 6.33% in total heat release and 13.6% in total smoke release, whereas increment by 23% in tensile strength and 12.1% in elongation at break, respectively. It is suggested that the introduction of silicone on the surface of EG can improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion process of the composites.     

可控自组装DNA折纸结构作为药物载体的研究进展

在过去的几十年里, DNA纳米技术作为一种快速发展的可控自组装技术, 使人们能构建出各种复杂的纳米结构. DNA折纸结构具备可编程性、 空间可寻址性、 易修饰性及良好的生物相容性等多种优越的特性, 这些优异的性质使其在药物递送方面具有广阔的应用前景. 本文总结了近年来可控自组装DNA折纸结构作为药物递送系统的研究进展, 展望了DNA折纸纳米载体未来的发展方向, 并讨论了该领域面临的挑战和可能的解决方法.     

A DNA Origami-Based Gene Editing System for Efficient Gene Therapy in Vivo

DNA nanostructures have played an important role in the development of novel drug delivery systems. Herein, we report a DNA origami-based CRISPR/Cas9 gene editing system for efficient gene therapy in vivo. In our design, a PAM-rich region precisely organized on the surface of DNA origami can easily recruit and load sgRNA/Cas9 complex by PAM-guided assembly and pre-designed DNA/RNA hybridization. After loading the sgRNA/Cas9 complex, the DNA origami can be further rolled up by the locking strands with a disulfide bond. With the incorporation of DNA aptamer and influenza hemagglutinin (HA) peptide, the cargo-loaded DNA origami can realize the targeted delivery and effective endosomal escape. After reduction by GSH, the opened DNA origami can release the sgRNA/Cas9 complex by RNase H cleavage to achieve a pronounced gene editing of a tumor-associated gene for gene therapy in vivo. This rationally developed DNA origami-based gene editing system presents a new avenue for the development of gene therapy.