Evaluation of approximations for concentration-dependent micropore diffusion in sorbent with bidisperse pore structure

Average diffusivity linear driving force (AD-LDF) and concentration-dependent diffusivity linear driving force (CDD-LDF) approximations are introduced to simplify the precise model describing the concentration-dependent micropore diffusion in bidisperse sorbents, and are compared with the precise model in predicting the dynamics of a sorption process under two different perturbations (i.e., step change perturbations and sinusoidal wave perturbation) with different concentrations imposed at the exterior surface of the bidisperse sorbent. The performance of the two approximations is validated by the precise model and experiments. The AD-LDF performs better in step adsorption and CDD-LDF does better in step desorption. Under sinusoidal wave perturbation, the CDD-LDF performs better. The different levels of consistency of the two approximations with the precise model are attributed to the different definitions of the diffusivities.     

Synthesis of fluorine-substituted [2.2]paracyclophane-based carbene precursors for copper-catalyzed enantioselective boration of α,β-unsaturated ketones

Fluorine-substituted [2.2]paracyclophane-based carbene precursors have been successfully synthesized and applied to copper-catalyzed asymmetric β-boration of α,β-unsaturated ketones. Fluorination of the planar chiral carbenes has a beneficial impact on the catalytic performance of the relevant complexes. A variety of chiral β-boryl ketones were obtained in excellent yields (up to 99%) and with high enantioselectivities (up to 99% ee).     

Improving nonlinearity tolerance of 112-Gb/s PDM OFDM systems with coherent detection using BLAST algorithm

A novel long wavelength photodetector with dual-wavelength spectral response is designed and fabricated using a step-shaped Fabry-Prot (F-P) filter structure.The step-shaped GaAs/AlGaAs distributed Bragg reflectors and the InP PIN photodetector are grown on a GaAs substrate using low pressure metal organic chemical vapor deposition.High quality GaAs/InP heteroepitaxy is realized by employing a thin low temperature buffer layer.The photodetector structure is optimized by theoretical simulation.This device has a dual-peak distance of 19 nm (1 558 and 1 577 nm).The 3-dB bandwidth of 16 GHz is simultaneously obtained with peak quantum efficiencies of 8.5% and 8.6% around 1 558 and 1 577 nm,respectively.     

Properties of cat-eye modulating retro-reflector and its application with piezoelectric transducer

Piezoelectric cat-eye modulating retro-reflector (MRR) is the core component of an acousto-optic retro-identification system. The influence of the optical parameters (link distance l, lens focal length f and the detector diameter r) to the cat-eye effect was analyzed theoretically and experimentally. A piezoelectric cat-eye retro-identification (PCERI) system was built, and an information transmission ratio of 2 kHz was achieved which can satisfy an access control system.     

基于Matlab GUI的微观化学反应过程可视化设计

Based on the quasi-classical trajectory (QCT) method and Matlab GUI technology, we developed a program code for visualizing the collision process of the elementary chemical reactions of the a + bc type. The general methodology of QCT, abstraction of dynamical properties of molecular collisions and the making of Graphical User Interface are introduced. The running results of an application to the reaction F + HCl→HF + Cl is also presented. The results showed that this program could vividly demonstrate the behavior and final state of the atom-diatom collision process in animated form. Students can interact with internal MATLAB code through graphical user interface, observe the reactive behavior and final results in real-time from multiple angles, which helps students to understand the complex reaction mechanism and deepen their perceptual impression of the chemical process at a microscopic atomic/molecular level.     

The impact of environmental regulations on forest product trade in China

Forest product trade plays an important role in the development of the Chinese forest industry. The trading value of forest product has shown a yearly growth rate of 12% during the last five recent years. Stringent environmental regulations in China have a profound impact on raw material supplies and industrial production in the forest sector; however, their impact on the forest product trade is still unclear. This study applies fixed and random effects models as well as a seemingly unrelated regression model to investigate the impact of environmental regulations on the trade of forest product from 2002 to 2015. The results indicate that the stringent environmental regulations promoted the import but restricted the export of forest product in general. Specifically, the stringent environmental regulations stimulated the import but had an ambiguous impact on the export of the paper product. The stringent environmental regulations had also stimulated the import of wood product but inhibited the export. In contrast, wooden furniture had been affected minimally; only export got slightly negatively affected by environmental regulations. Recommendations for resource managers:

• Trade‐offs between economic growth and environmental regulations are needed to smoothly promote the forest product trade in China.
• Paper and wooden furniture product sectors are less likely to be affected by stringent environmental regulations, because high value‐added products could compensate for environmental costs.
• The wood product sector is more likely to be negatively affected by stringent environmental regulations because environmental costs could severely impact the competitiveness of low value‐added products.

     

Ground state cooling of an optomechanical resonator with double quantum interference processes

We present a cooling scheme with a tripod configuration atomic ensemble trapped in an optomechanical cavity.With the employment of two different quantum interference processes,our scheme illustrates that it is possible to cool a resonator to its ground state in the strong cavity-atom coupling regime.Moreover,with the assistance of one additional energy level,our scheme takes a larger cooling rate to realize the ground state cooling.In addition,this scheme is a feasible candidate for experimental applications.     

SOCP reformulation for the generalized trust region subproblem via a canonical form of two symmetric matrices

Mathematical Programming - We investigate in this paper the generalized trust region subproblem (GTRS) of minimizing a general quadratic objective function subject to a general quadratic inequality...     

High-reflectivity non-periodic sub-wavelength gratings with small-angle beam-steering ability and its application in Fabry–Perot cavity

We report a high-reflectivity non-periodic sub-wavelength gratings (SWGs) mirror with small-angle beam-steering ability for reflect light. It presents a distinctive characteristic of flexibly controlling the width of oscillation optical field for the improved Fabry–Perot (F–P) cavity. We propose a detailed principle analysis of the improved cavity. By finding out a set of SWGs with the designed structural parameters, both high reflectivity (>?93%) and beam steering (1°) can be implemented. By setting beam-steering angle and cavity length, we can control the width of oscillation optical field in the improved cavity. Beam steering ability and property of controlling the oscillation width are numerically investigated by finite element method. Simulation results prove that cavity length and steering angle can effectively control the main width of oscillation optical field, and the width is linearly associated with the cavity length.     

Cycloparaphenylene and their radicals anchored to a metal−organic framework

Cycloparaphenylene (CPP) shows modulated photophysical and electronic properties due to its strained structure and radially oriented π-electron system. Incorporation of CPP into metal-organic frameworks (MOFs) could transfer its extensive properties in solution to porous solids. Moreover, with the unique arrangement of the macrocycles and their interactions with the framework, emerging characteristics are anticipated. As an example of “robust dynamics”, we synthesized the first MOF structure (FDM-1001) with CPP precisely anchored to the ordered framework by employing a [8]CPP-containing linear dicarboxylate linker. Metric relationship between the dynamic macrocycles and the robust backbone creates ideal π-π interactions between them, which leads to an essentially directional arrangement of [8]CPP in the three-dimensional space. Furthermore, the MOF with [8]CPP could be successfully oxidized to generate an infinite array of radicals that show enhanced air stability compared to its molecular analogue.