离子液体萃取铂、钯和铑离子的研究进展

铂族金属作为一类不可再生资源,在工业和军工方面有着重要应用,但其在分配和供求上存在严重不均衡,凸显了其资源化回收再利用的重要性。离子液体作为一种性质优良的绿色溶剂,成为科学研究的热点。本文对近年来利用离子液体萃取铂族金属铂、钯和铑等的研究进行了综述,并对其未来的发展方向进行了展望。     

Classical mean-variance model revisited: pseudo efficiency

Investigating the inverse problem of the classical Markowitz mean-variance formulation: Given a mean-variance pair, find initial investment levels and their corresponding portfolio policies such that the given mean-variance pair can be realized, we reveal that any mean-variance pair inside the reachable region can be achieved by multiple portfolio policies associated with different initial investment levels. Therefore, in the mean-variance world for a market of all risky assets, the common belief of monotonicity: ‘The larger you invest, the larger expected future wealth you can expect for a given risk (variance) level’ does not hold, which stimulates us to extend the classical two-objective mean-variance framework to an expanded three-objective framework: to maximize the mean and minimize the variance of the final wealth as well as to minimize the initial investment level. As a result, we eliminate from the policy candidate list the set of pseudo efficient policies that are efficient in the original mean-variance space, but inefficient in this newly introduced three-dimensional objective space.     

Visualization of high-order dispersion for compression of few-cycle pulses

We present a visually intuitive method for higher-order dispersion compensation based on multi-photon interpulse interference pulse scans. The dispersion values obtained from these scans are fed back as a correction to an acousto-optical programmable dispersive filter to compensate residual higher-order dispersions up to fifth order. This method is applied to the dispersion management of a non-collinear optical parametric chirped-pulse amplifier. A grism-pair stretcher is designed based on a global dispersion balance which provides a large stretching factor and supports a spectral bandwidth of up to 320 nm. It is implemented in a two-stage three-pass non-collinear optical parametric chirped-pulse amplifier and stretches 6-fs seed pulses to about 80 ps from 700 to 1,000 nm. The amplified pulses are compressed by material dispersion. Pulses of less than 10-fs duration with a pulse energy of 125 μJ are obtained at 20-kHz repetition rate.     

Three-dimensional structural features and the toxicity of aminobenzenes and phenols

There are many organic pollutants in the environment, such as polychlorinated biphenyl, polycyclic aromatic hydrocarbons, dichlorodiphenyl-trichloroethane (DDT), and polychlorinated naphthalene. These organic pollutants are persistent,liposoluble and easily cumulated in organism; consequently, the potential toxicity will be high. Risk assessment of industrial chemicals is currently carried out using scanty experimental data, because many of these chemicals have very little or no test data. S…     

距离边数矢量与分子相似度的计算

化学环境编码算法;分子相似度计算;距离边数矢量与分子相似度的计算     

Thermal lens determination of LD end-pumped solid-state laser with stable resonator by slit scanning method

A simple method to determine the thermal focal length of LD end-pumped solid-state laser with stable resonator is presented. The M² factor describing the quality of the beam can be obtained by scanning a slit through the multi-mode Gaussian beam field. The waist width of the beam and the corresponding TEM₀₀ under the same parameters of laser are then deduced through the law of multi-mode Gaussian beam propagation. Based on the standard matrix theory of stable resonator, the thermal focal length of the gain medium can be easily achieved. To show the application of this approach, the thermal focal length of an LD pumped Nd:YVO₄ laser is measured and the experimental results are in agreement with the theoretical prediction.     

Synthesis of polyfunctional imidazoles from vinyl azides and amidine along with NHBoc as a leaving group

An efficient method for the synthesis of polyfunctional imidazoles from vinyl azides and amidine has been developed. Starting from vinyl azide and amidine, this transformation proceeds without any additives and the obtained imidazoles can be decorated with ester functional group that is a promising site for further modification.     

Synthesis and Biological Evaluation of Entecavir 4'-Ester Derivatives

Entecavir can significantly inhibit the replication of HBV-DNA, reduce the HBV-DNA level in blood se- rum. But suffering from low oral bioavailability, entecavir has low intestinal membrane permeability and poor meta- bolic stability. In this study, 12 different derivatives of entecavir 4＇-ester were regioselectively synthesized and their apical-to-basolateral permeabilities across Caco-2 cells and HBV-DNA inhibitory efficacies were evaluated. Most of the compounds showed high permeabilities across Caco-2 cells compared with entecavir, compounds 5b and 5e also exhibited comparable anti-HBV activities with that of entecavir, especially.     

A facile approach to polysubstituted pyrazoles from hydrazonyl chlorides and vinyl azides

A novel and facile approach to polysubstituted pyrazoles from readily synthesized hydrazonyl chlorides and vinyl azides was developed. The reaction was regiospecific and proceeded under mild conditions in the presence of base.