Effect of charge on the stability of single-walled carbon nanotubes

Carbon nanotubes can be viewed as a complete tube structure formed from graphitelayers and they have long been a research focus since the discovery in 1991[1,2]. Due totheir distinct atomic and electronic structures, carbon nanotubes, especially single-walled carbon nanotubes (SWNTs), have got into the frontier of the nanoelectronics andthe molecular electronics[3], in addition to their applications in the field of material sci-ence. After successfully manufacturing model electronic devices[4…     

Quantum Image Encryption Based on Quantum Image Decomposition

Aiming at the slow processing speed of classic image encryption algorithms and the security analysis of existing quantum image encryption algorithms, this paper combines the representation method of quantum images and proposes a quantum image encryption algorithm based on image correlation decomposition. Using the principle of quantum state superposition and measurement, the association between image pixels is established, the image is decomposed into a series of feature sub-images and stored in a complete binary tree set, and different sub-images are operated and encrypted by random phase operation and quantum rotation operation. Then superimpose all the sub-images to obtain the ciphertext image. The algorithm has a larger key space so that it can resist brute force attacks. At the same time, the quantum encryption algorithm has lower computational complexity than classic encryption algorithms. In addition, because the ciphertext image is transmitted in the communication channel in the form of a quantum state, the security of quantum image encryption also surpasses the security of classical image encryption.

     

高效液相色谱法同时测定罗汉果中的六种葫芦烷三萜类皂苷

建立了高效液相色谱测定罗汉果中罗汉果苷Ⅴ、罗汉果苷ⅣA、罗汉果苷Ⅲ、11-氧化罗汉果苷Ⅲ、罗汉果苷ⅡE和11-氧化罗汉果苷ⅡE等6种苷类化合物含量的方法。采用的色谱条件：ZORBAX SB-C18色谱柱(150 mm×4.6 mm, 5 μm);柱温30 ℃;以水(A相)和乙腈(B相)为流动相,梯度洗脱程序：0～3 min,20%B～30%B;3～8 min,30%B～35%B;8～9 min,35%B;流速0.8 mL/min;检测波长203 nm;进样量10 μL。结果表明,以上6种苷类化合物分别在0.04～1.0 mg/mL、0.011～0.68 mg/mL、0.010～0.80 mg/mL、0.0097～0.58 mg/mL、0.025～1.0 mg/mL、0.013～0.76 mg/mL范围内线性关系良好(r＞0.9991)。加标回收率依次为99.65%,101.6%,97.05%,103.1%,99.25%和103.0%;相对标准偏差分别为0.83%,3.1%,1.9%,3.3%,0.59%和2.0%。该方法简便、快速、准确,适用于罗汉果原材料及其制品中苷类化合物的检测和含量测定。     

Biodegradable anastomotic tube prepared from diblock copolymers of mPEG-b-PLA and mPEG-b-PLGA

During the healing and reconstruction process of digestive tract, biodegradable anastomat plays an important role. Various of materials have been explored to prepare suitable anastomat. However, the biodegradable ratio or biocompatibility could not meet the requirement of wound healing in clinical application. To overcome these obstacles, we synthetized methoxy-poly(ethylene glycol)-block-polylactide (mPEG-b-PLA) and methoxy-poly(ethylene glycol)-block-poly(lactide-co-glycolide) (mPEG-b-PLGA) with different molecular weight. Biodegradable anastomotic tubes were prepared from these diblock copolymers using electrospinning technique. The thickness of anastomotic tube could be regulated by spinning conditions. Anastomotic tubes had exhibited excellent hemocompatibility (hemolysis ratios were ranged from 0.5% to 1.5%) and cytocompatibility. After 3?days, epithelial cells were adhered closely and covered fully on the surface of nanofibrous tubes. Moreover, mPEG-b-PLGA₃ based anastomotic tube had play an important role to improve the healing and reconstruction process of cecal incision. The biodegradable anastomotic tubes from diblock copolymers of mPEG-b-PLA and mPEG-b-PLGA could promote healing and reconstruction of digestive tract and might play an important role after operation.     

Deep oxidative desulfurization of fuels catalyzed by molybdovanadophosphoric acid on amino-functionalized SBA-15 using hydrogen peroxide as oxidant

This study reports the usage of molybdovanadophosphoric acid catalyst on amino-functionalized SBA-15(PMoV₂/SBA-15-NH₂) for the removal of sulfur from model oil (dibenzothiophene dissolved in n-hexane). To increase the tendency for adsorption of heteropoly acids, mesoporous SBA-15 silica was functionalized with amino groups by postsynthesis grafting, using 3-aminopropyltrimethoxy silane as the coupling agent. Immobilization of molybdovanadophosphoric acid on pure SBA-15 (PMoV₂/SBA-15) was also studied for comparison and the catalysts were characterized by physicochemical and spectroscopic methods. It was found that the catalysts exhibit high catalytic activities and PMoV₂/SBA-15-NH₂ is more durable than PMoV₂ impregnated on unmodified mesoporous SBA-15 silica. The results may bring about improvement for oxidative desulfurization of transportation fuels.     

Crystal structure, coloring problem and magnetism of Gd(5-x)Zr(x)Si4

Ternary Gd(5-x)Zr(x)Si(4) silicides were synthesized by arc melting of the constituent elements and subsequent heat treatments. The Gd(5-x)Zr(x)Si(4) phases adopt the orthorhombic Gd(5)Si(4)-type (space group Pnma) structure for x≤ 0.25 and the tetragonal Zr(5)Si(4)-type (space group P4(1)2(1)2) structure for x≥ 1.0, respectively. The samples with intermediate compositions contain two phases. Single-crystal X-ray diffraction reveals a preferential site occupancy for Zr on the three metal sites in the order of M3 > M2 > M1. Size arguments based on the local coordination environments suggest that the larger Gd atoms preferentially occupy the larger M1 site, while the smaller Zr atoms tend to occupy the smaller metal sites, M2 and M3. Tight-binding linear-muffin-tin orbital calculations illustrate a role of the metal-silicon bonds in the metal site occupation. An increase in the valence electron concentration through the Zr substitution weakens the Si-Si interactions but enhances the metal-silicon and metal-metal interactions. The Curie temperature of Gd(5-x)Zr(x)Si(4) decreases gradually with the increasing Zr content.     

Amperometric Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Immobilized on Fe3O4/Chitosan Modified Glassy Carbon Electrode

A new type of amperometric hydrogen peroxide biosensor was constructed based on horseradish peroxidase (HRP) immobilized on Fe₃O₄/chitosan modified glassy carbon electrode. The effects of some experimental variables such as the concentration of supporting electrolyte, pH, enzyme loading, the concentration of the mediator of methylene blue (MB) and the applied potential were investigated. The linear range of the calibration curve for H₂O₂ was 2.0×10^?4–1.2×10^?2 M with a detection limit of 1.0×10^?4 M (S/N=3). The response time was less than 12 s. The apparent Michaelis‐Menten constant K_m was 21.4 mM and it illustrated the excellent biological activity of the fixed enzyme. In addition, the biosensor had long‐time stability and good reproducibility. And this method has been used to determine H₂O₂ concentration in the real sample.     

Wide-coverage and Efficient NIR Emission from Single-component Nanophosphors through Shaping Multiple Metal-halide Packages

Wide-coverage near infrared (NIR) phosphor-converted LEDs possess promising potential for practical applications, but little is developed towards the efficient and wide-coverage NIR phosphors. Here, we report the single-component lanthanide (Ln³⁺) ions doped Cs₂M(In_0.95Sb_0.05)Cl₆ (M=alkali metal) nanocrystals (NCs), exhibiting emission from 850 to 1650 nm with high photoluminescence quantum yield of 20.3 %, which is accomplished by shaping the multiple metal halide octahedra of double perovskite via the simple alkali metal substitution. From Judd-Ofelt theoretical calculation and spectroscopic investigations, the shaping of metal halide octahedra in Cs₂M(In_1−xSb_x)Cl₆ NCs can break the forbidden of f-f transition of Ln³⁺, thus increasing their radiative transition rates and simultaneously boosting the energy transfer efficiency from host to Ln³⁺. Finally, the wide-coverage NIR LEDs based on Sm³⁺, Nd³⁺, Er³⁺-tridoped Cs₂K_0.5Rb_0.5(In_0.95Sb_0.05)Cl₆ NCs are fabricated and employed in the multiplex gas sensing and night-vision application.     

Electrochemical Reaction Mechanism of Phenacetin at a Carboxylated Multiwall Carbon Nanotube Modified Electrode and Its Analytical Applications

A novel type of carboxylated multiwalled carbon nanotube modified electrode（c-MWCNTs/GCE） was constructed and the electrochemical properties of phenacetin（PHE） at it were studied. In a buffer solution of 0.1 mol/L HAc-NaAc（pH=5.3）, PHE exhibited a couple of quasi-reversible redox peaks and an anodic peak in the poten- tial range of 0.2--1.2 V at c-MWCNTs/GCE. The peak current was proportional to the concentration of PHE in the range of 4.0× 10^-6_ 1.0 × 10^-4 mol/L with a detection limit of 1.0× 10^-6 mol/L（S/N=3）. The c-MWCNTs/GCE showed excellent repeatability and stability and the electrochemical reaction mechanism of PHE was proposed. This method was used to determine the content of PHE in medical tablets and the recovery was determined to be 96.5%--104.2% by means of a standard addition method.     

润滑油密度与黏度关系的进一步探讨及定量广义牛顿热弹流数值分析

基于"同一油品相同的密度对应相同的黏度"这一假说,本文作者将最近提出的在等温条件下由密度求黏度的计算公式推广到热条件之下并进行了进一步的理论探讨.通过引入广义黏度,把润滑油的Eyring流动处理为广义牛顿流动,进而对由squalane油润滑的点接触副在不同赫兹接触压力和卷吸速度下,在滑滚比宽广的变化范围内开展了定量的热弹流数值仿真.仿真得到的摩擦系数与试验结果良好的吻合程度不但证实了作者的由密度求黏度公式在热条件下仍然准确,同时也证实了所用的密度与黏度关系假说的合理性.在比较新黏度公式与Barus、Roelands和Doolittle黏度公式所得数值仿真结果时,提出了一种不需要黏温系数而得到热条件下润滑油黏度值的算法,并用之得到了合理的广义牛顿热弹流解.