Process design and intensification of multicomponent azeotropes special distillation separation via molecular simulation and system optimization

This work provides an overview of distillation processes,including process design for different distillation processes,selection of entrainers for special distillation processes,system integration and intensification of distillation processes,optimization of process parameters for distillation processes and recent research progress in dynamic control strategies.Firstly,the feasibility of using thermodynamic topological theories such as residual curve,phase equilibrium line and distillation boundary line to analyze different separation regions is discussed,and the rationality of distillation process design is discussed by using its feasibility.Secondly,the application of molecular simulation methods such as molecular dynamics simulation and quantum chemical calculation in the screening of entrainer is discussed for the extractive distillation process.The thermal coupling mechanism of different distillation processes is used to explore the process of different process intensifications.Next,a mixed integer nonlinear optimization strategy for the distillation process based on different algorithms is introduced.Finally,the improvement of dynamic control strategies for different distillation processes in recent years is summarized.This work focuses on the application of process intensification and system optimization in the design of distillation process,and analyzes the challenges,prospects,and development trends of distillation technology in the separation of multicomponent azeotropes.

人直肠异常隐窝病灶的2年随访研究

目的:异常隐窝病灶(aberrant crypt foci,ACF)目前被广泛认为是光镜下可视最早期的大肠癌癌前病变。本研究在2年时间通过结肠镜下动态观察ACF的变化来初步探讨ACF与结直肠癌的关系。方法:选取2013年1月至2014年12月在山西医科大学第二医院接受结肠镜检查并排除常见致癌及抑癌因素的100例患者,常规在退镜时进行直肠靛胭脂染色,观察并记录初次结肠镜检查、1年及2年复查肠镜时直肠ACF的数目及单个ACF的自然发展变化过程。结果:初次检查及1年和2年后的ACF阳性率比较,差异无统计学意义。ACF随时间的变化大部分继续存在或自行消失,少数发展为息肉、腺瘤,ACF<6枚的病例,以及腺管开口为椭圆形的ACF自行消失率更大,而腺管开口为非椭圆形者更易发展为息肉或腺瘤。结论:ACF变化呈异质性,其中部分可能为大肠癌癌前病变。

Organoid Technology and Clinical Applications in Digestive System Cancer

Cancers of the digestive system(DS),including esophageal,gastric,colorectal,liver,and pancreatic can-cers,have a high incidence and mortality worldwide.Current cancer models cannot faithfully recapitu-late the critical features of the original tumor,resulting in the failure of translation from basic research into clinical practice.More advanced cancer models are in urgent need of pathogenesis exploration and anticancer medicine development.Organoids are in vitro cultured three dimensional(3D)self-organizing organotypic structures derived from tissues and pluripotent stem cells,which faithfully mimic the histological features and preserve the genetic heterogeneity of the original tissues.Both normal and malignant organoids can now be efficiently established from the DS tissues of patients.In this review,we summarize the general methods to generate human DS organoids and their applications as a novel model in basic cancer research,preclinical medical practice,and precision medicine.

Analysis of microwave propagation in a time-varying plasma slab with particle-in-cell simulations

Continuous microwave propagation through a time-varying plasma and frequency up-conversion has been demonstrated by particle-in-cell (PIC) simulation. In principle, it is possible to transform a 2.45 GHz source radiation to an arbitrary larger frequency radiation. The energy conversion is also obtained by the theoretical analysis and has been testified by PIC simulation. The source wave was propagating in a parallel plate waveguide locally filled with the ionized gas. In this paper we would discuss the effects of the rise time, the plasma length, the switching time and the collision frequency on the energy conversion, and the methods to improve the upshift wave energy are proposed. We also put forward the new concept of the critical values of the rise time and the source wave amplitude to provide a theoretical basis for the selection of parameters in the experiments.

Investigation on current loss of high-power vacuum transmission lines with coaxial-disk transitions by particle-in-cell simulations

Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current loss.In this paper,3 D particle-in-cell simulations are conducted with UNPIC-3 d to investigate the current loss mechanism and the influence of the input parameters of the coaxial-disk transition on current loss in an MITL system.The results reveal that the magnetic field non-uniformity causes major current loss in the MITL after the coaxialdisk transition,and the non-uniformity decreases with the distance away from the transition.The uniformity of the magnetic field is improved when increasing the number of feed lines of a linear transformer driver-based accelerator with coaxial-disk transitions.The number of input feed lines should be no less than four in the azimuthal distribution to obtain acceptable uniformity of the magnetic field.To make the ratio of the current loss to the total current of the accelerator less than 2%at peak anode current,the ratio of the current in each feed line to the total current should be no less than 8%.

Microwave frequency downshift in the time-varying collision plasma

Microwave frequency downshift in the time-varying collision plasma has been demonstrated by particle-in-cell simulations.The simulation results are consistent with the theoretical analysis,and the preconditions for microwave frequency downshift are that the collision frequency needs to be greater than the incident wave frequency,and the plasma frequency is two times greater than the incident wave frequency.Finally,the simulation results are compared with the reported experimental results indicating good agreement.

Amplification of terahertz/infrared field at the nodes of Ranvier for myelinated nerve

The myelination of axons was the last major evolution in the vertebrate nervous system.Myelin promotes the speed of action potential by two orders,and modulates the conduction of neurons,important for learning new skills.However,the intrinsic mechanism for high-speed information propagation in myelin in the nervous systems is still unclear.We propose that myelinated nerve fibres serve as dielectric waveguides for the high-frequency electromagnetic information in a certain mid-infrared to terahertz spectral range.Based on the structure characteristics of myelinated nerve composed of periodic nodes of Ranvier and myelin sheath,the energy for the signal propagation is supplied and amplified when crossing the nodes of Ranvier via a periodic relay.In this work,we exploit the quasi-quantum model of amplification for neural terahertz/infrared information at the nodes of Ranvier,and prove the existence of biomolecular ensemble for three-energy-level amplification,revealing the essential mechanism of high-speed electromagnetic information transmitting in myelinated nerves.

Nonlinear topological valley Hall edge states arising from type-Ⅱ Dirac cones

A Dirac point is a linear band crossing point originally used to describe unusual transport properties of materials like graphene.In recent years,there has been a surge of exploration of type-II Dirac/Weyl points using various engineered platforms including photonic crystals,waveguide arrays,metasurfaces,magnetized plasma and polariton micropillars,aiming toward relativistic quantum emulation and understanding of exotic topological phenomena.Such endeavors,however,have focused mainly on linear topological states in real or synthetic Dirac/Weyl materials.We propose and demonstrate nonlinear valley Hall edge(VHE)states in laserwritten anisotropic photonic lattices hosting innately the type-Ⅱ Dirac points.These self-trapped VHE states,manifested as topological gap quasi-solitons that can move along a domain wall unidirectionally without changing their profiles,are independent of external magnetic fields or complex longitudinal modulations,and thus are superior in comparison with previously reported topological edge solitons.Our finding may provide a route for understanding nonlinear phenomena in systems with type-Ⅱ Dirac points that violate the Lorentz invariance and may bring about possibilities for subsequent technological development in light field manipulation and photonic devices.