Spiropyran-Based Nanocarrier: A New Zn2+-Responsive Delivery System with Real-Time Intracellular Sensing Capabilities

A new spiropyran-based stimuli-responsive delivery system is fabricated. It encapsulates and then releases an extraneous compound in response to elevated levels of Zn²⁺, a critical factor in cell apoptosis. A C₁₂-alkyl substituent on the spiropyran promotes self-assembly into a micelle-like nanocarrier in aqueous media, with nanoprecipitation and encapsulation of added payload. Zn²⁺ binding occurs to an appended bis(2-pyridylmethyl)amine group at biologically relevant micromolar concentration. This leads to switching of the spiropyran (SP) isomer to the strongly fluorescent ring opened merocyanine-Zn²⁺ (MC-Zn²⁺) complex, with associated expansion of the nanocarriers to release the encapsulated payload. Payload release is demonstrated in solution and in HEK293 cells by encapsulation of a blue fluorophore, 7-hydroxycoumarin, and monitoring its release using fluorescence spectroscopy and microscopy. Furthermore, the use of the nanocarriers to deliver a caspase inhibitor, Azure B, into apoptotic cells in response to an elevated Zn²⁺ concentration is demonstrated. This then inhibits intracellular caspase activity, as evidenced by confocal microscopy and in real-time by time-lapsed microscopy. Finally, the nanocarriers are shown to release an encapsulated proteasome inhibitor ( 5 ) in Zn²⁺-treated breast carcinoma cell line models. This then inhibits intracellular proteasome and induces cytotoxicity to the carcinoma cells.     

Recent advances of scanning electrochemical microscopy and scanning ion conductance microscopy for single-cell analysis

Single-cell analysis is important for understanding fundamental biological processes and mechanisms. Scanning electrochemical microscopy and scanning ion conductance microscopy as two kinds of scanning probe microscopy, with high temporal and spatial resolutions as well as in situ and noninvasive characterization capabilities, emerge as strong tools for single-cell analysis. In this review, we introduce the latest advances of scanning electrochemical microscopy and scanning ion conductance microscopy for single-cell analysis, including characterizations of cell morphology dynamics, membrane properties and mechanics, and monitoring cell surface charge, extracellular pH, and intracellular substances.     

A note on a result of Kong about p-nilpotency

Monatshefte für Mathematik - We point out an error in the paper ‘On an extension of the Frobenius’ theorem about p-nilpotency of a finite group’ (Monatsh Math...     

结构可靠指标求解的一种新的迭代方法

由国际安全度联合委员会推荐的一次二阶矩可靠度方法是国际工程界公认的一种较好的可靠度分析方法（简称ＪＣ法）。这种方法具有迭代格式简单，收敛快的特点。但许多实际计算表明，这种方法只适用于功能函数非线性程度不高的情况，否则不收敛。本文提出一种新的迭代方法，这种方法迭代格式与ＪＣ法同样简单，一般情况下均能保证收敛．     

AN IMPROVED IRS METHOD FOR STRUCTURE MODEL CONDENSATION1)

模型缩聚法在结构的静力和动力特性分析中有着广泛的应用。应用模型缩聚法,可以有效降低结构的有限元计算规模,节省计算时间和成本,并能获得和实验测量自由度相匹配的有限元模型。本文在改进模型缩聚方法(improved reduced system, IRS)的基础上,提出一种考虑二阶惯性量的改进IRS方法,有效改进了IRS方法的计算精度,和模型缩聚迭代法(iterated IRS, IIRS)相比,此方法计算量更小且计算精度更高。以桁架结构和框架结构为例对所提二阶IRS方法进行了验证,并将计算结果与精确值、Guyan缩聚解、IRS缩聚解和IIRS缩聚解进行了比较,结果表明了所提方法计算精度最好,具有良好的工程应用前景。     

Fe2O3-MWNTs Composite with Reinforced Concrete Structure as High-performance Anode Material for Lithium-ion Batteries

AFe₂O₃-MWNTs(multi-walled carbon nanotubes) composite with a reinforced concrete structure was fabricated employing a two-step method, which involves a sol-gel process followed by high-temperature in situ sintering. This Fe₂O₃-MWNTs composite, intended to be used as an anode material for lithium-ion batteries, maintained a reversible capacity as high as 896.3 mA·h/g after 100 cycles at a current density of 100 mA/g and the initial coulombic efficiency reached 75.5%. The rate capabilities of the Fe₂O₃-MWNTs composite, evaluated using the ratios of capacity at 100, 200, 500, 1000, 2000 and 100 mA/g after every 10 cycles, were determined to be 904.7, 852.1, 759.0, 653.8, 566.8 and 866.3 mA·h/g, respectively. Such a superior electrochemical performance of the Fe₂O₃-MWNTs composite is mainly attributed to the reinforced concrete construction, in which the MWNTs function as the skeleton and conductive network. Such a structure contributes to shortening the transport pathways for both Li⁺ and electrons, enhancing conductivity and accommodating volume expansion during prolonged cycling. This Fe₂O₃-MWNTs composite with the designed structure is a promising anode material for high-performance lithium-ion batteries.     

Construction of a Recombinant <Emphasis Type="Italic">S. cerevisiae</Emphasis> Expressing a Fusion Protein and Study on the Effect of Converting Xylose and Glucose to Ethanol

Gene XYL1 from Candida shehatae and gene XYL2 from Pichia stipitis were amplified by polymerase chain reaction (PCR), and the two genes were both placed under the strong promoter of alcohol dehydrogenase (ADH) of plasmid pAD2 to produce the recombinant expression vector pAD2-P12. Because the amplified XYL1 fragment lacks the stop codon UAA, the polypeptide expressed in yeast cells should be a fusion protein, which is a fusion of xylose reductase and xylitol dehydrogenase. Subsequently, the pAD2-P12 vector was transformed into Saccharomyces cerevisiae YS58 to produce a recombinant S. cerevisiae YS58-12. It was indicated that S. cerevisiae YS58-12 has the ability of metabolizing xylose to produce ethanol by fermentation experiment. The result of cofermentation of glucose and xylose by using this recombinant S. cerevisiae YS58-12 showed a relatively satisfactory result. The highest percentage of xylose consumption rate reached 81.3% and the ethanol yield was equal to 67.14% of the ideal value.     

Novel 2N bit bipolar photonic digital-to-analog converter based on optical DQPSK modulation coupled with differential detection

A novel 2N bit bipolar photonic digital-to-analog converter (PDAC) scenario based on the optical differential quadrature phase shift keying (ODQPSK) modulation coupled with differential detection is proposed. Compared with other proposed schemes, this bipolar PDAC has a greater dynamic range and a larger noise margin with good scalabilities both in speed and resolution. We demonstrate a 4 bit PDAC in a proof-of-principle experiment at a sampling rate of 2.5 GS/s.     

反相高效液相色谱法同时测定土壤中莠去津,氰草津残留量方法研究

提出了用高效液相色谱法同时测定土壤中莠去津、氰草津残留量的方法。用甲醇／乙腈提取，石油醚脱脂，中性氧化铝小柱净化，最后用Ｎｏｖａ－ＰａｋＣ１６柱进行ＨＰＬＣ分析，流动相：甲醇－水（５５＋４５），吸收波长 ２２８ ｎｍ，流速０． ７ ｍＬ／ｍｉｎ．莠去津最低检出限为 ０．３ ｎｇ，氰草津为０．２ ｎｇ。回收率分别为莠去津８３．４％～１０２．３％，氰草津 ８２．４％～９３．５％．