Transformations of iodine species inside elliptical channels of AlPO4‐11 crystals at low temperature: a Raman study

Raman spectra of iodine species confined in one‐dimensional elliptical channels of AlPO₄‐11 (AEL) crystals have been studied from room temperature down to −196 °C. As temperature decreases, thermal fluctuations of individual iodine molecules confined in AEL channels are slowed down and they prefer to rotate to channel axis direction, which increases the population of iodine molecules along channel axis (i.e., lying molecules and chains). Such temperature‐driven orientation transformation of iodine molecules is found to be reversible upon heating up to room temperature. The experimental observations are in good agreement with our theoretical simulations by molecular dynamics on low density iodine‐filled AEL crystals. We thus provide a new way to modulate the orientation of iodine molecules in nanochannels, which may have implications in low‐temperature‐sensitive nanoscale devices. Copyright © 2015 John Wiley & Sons, Ltd.     

Characterization and properties of plywood bioadhesive derived from cottonseed protein and sawdust cellulose

Cellulose - The development of plant adhesive with good bonding strength, water resistance and thermal stability remains challenging to replace formaldehyde-based adhesive resins that usually...     

The Total Solubility of the Co-Solubilized PAHs with Similar Structures Indicated by NMR Chemical Shift

The synergism/inhibition level, solubilization sites and the total solubility (S_t) of co-solubilization systems of phenanthrene, anthracene and pyrene in Tween 80 and sodium dodecyl sulfate (SDS) are studied by ¹H-NMR, 2D nuclear overhauser effect spectroscopy (NOESY) and rotating frame overhauser effect spectroscopy (ROESY). In Tween 80, inhibition for phenanthrene, anthracene and pyrene is observed in most binary and ternary systems. However, in SDS, synergism is predominant. After analysis, we find that the different synergism or inhibition situation between Tween 80 and SDS is related to the different types of surfactants used and the resulting different co-solubilization mechanisms. In addition, we also find that three polycyclic aromatic hydrocarbons (PAHs) have similar solubilization sites in both Tween 80 and SDS, which are almost unchanged in co-solubilization systems. Due to the similar solubilization sites, the chemical shift changes of surfactant and PAH protons follow the same pattern in all solubilization systems, and the order of chemical shift changes is consistent with the order of changes in the St of PAHs. In this case, it is feasible to evaluate S_t of PAHs by chemical shift. In both Tween 80 and SDS solutions, the ternary solubilization system has relatively high S_t rankings. Therefore, in practical applications, a good overall solubilization effect can be expected.     

Progress of Jinping Underground laboratory for Nuclear Astrophysics (JUNA)

Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of~(25)Mg(p,γ)~(26)Al,~(19)F(p,α)~(16)O,~(13)C(α,n)~(16)O and ~(12)C(α,γ)~(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.     

Counterion-hopping along the backbone of single-stranded DNA in nanometer pores: a mechanism for current conduction

Molecular dynamics calculations are performed to investigate ionic current conduction through nanopores in the presence of single-stranded DNA. We find the counterions to be strongly attracted to the phosphate groups of the DNA, with resident time on the order of nanoseconds, while coions are strongly excluded. The diffusion constant of the counterions is calculated and used to estimate the ionic current through the pore, which gives a similar magnitude as in experiment. The results suggest a counterion-hopping mechanism along the ssDNA backbone in the current conduction through nanopores.     

Interference of a four-hole aperture for on-chip quantitative two-dimensional differential phase imaging

We present a novel on-chip method for quantitative two-dimensional differential phase imaging. This technique uses four circular holes (600 nm diameter, 1.2 mum spacing) arranged in a 'plus' pattern that are fabricated in a layer of metal above a complementary metal-oxide semiconductor (CMOS) imaging sensor. The interference pattern of the aperture shifts position with respect to the differential phase of the incident light. By imaging the interference pattern with the CMOS sensor, this method measures amplitude and differential phase (1 degrees /microm sensitivity for signal-to-noise ratio >/=16 dB) of the incident light field simultaneously. An application to optical beam profiling is presented; we show the amplitude and differential phase profiles of a Gaussian laser beam and an optical vortex.     

基于微机电系统技术的高性能集成型微富集器（英文）

由于大部分环境样品的浓度非常低,为了实现其直接检测,提出将一种集成化的微型富集器应用到色谱系统中。富集器可实现色谱系统的进样与样品富集,能将色谱仪的检测限提高1~2个数量级。设计的富集器采用了高容量4平行通道结构,沟道内填充了高吸附率的Tenax-TA吸附材料,来实现对环境样品中挥发性有机化合物组分的富集。此外,为了密闭热解吸过程中所释放的组分,在微型富集器后集成了微型阀。试验结果表明,研制的微型富集器取得了15倍以上的富集因子。而且,通过微阀的控制,色谱峰的拖尾和峰展宽得到了有效的控制。因此,该微型富集器可广泛应用到环境样品的快速检测中,提高各检测器对复杂环境的适应能力。     

弹簧参与的微小振动一定是简谐运动吗

振动和波动是生活中的一种非常普遍而重要的运动形式,其中简谐振动是最简单、最基本的运动,弹簧振子是研究简谐运动的最基本模型.在研究弹簧参与的微小振动时,部分学生不能很好的判定弹簧参与的微小振动是否为简谐运动.本文讨论了系统作简谐运动的充要条件,并通过4个具体例子详细分析了弹簧参与的微小振动.