Asphaltenes: Separations, structural analysis and applications

Asphaltenes, complex aromatic compounds from various carbonaceous sources, could be obtained by solvent dissolution, filtration and adsorption. It was difficult to clarify the molecular structures and chemical properties of asphaltene due to its structural similarity, composition complexity and source dependences. Many techniques, like Mass spectrometry, Chromatography, Nuclear magnetic resonance spectroscopy, Infrared spectroscopy, Roman spectroscopy, Fluorescence spectroscopy, X-ray diffraction analysis and Small-angle scattering techniques and so on, have revealed some valuable descriptions of asphaltenes chemical compositions and fundamental structures. Moreover, advanced Mass spectrometry,Atomic force microscopy and Scanning tunneling microscopy could provide more clear and essential molecular compounds and structures in asphaltenes. In addition, several asphaltenes models have succeeded to illustrate aggregation properties asphaltene. In this work, the progress on asphaltene separation, characterization and application was summarized, and the similarities and differences between coal-derived asphaltenes and petroleum asphaltenes were compared. Furthermore, the reactivity of asphaltenes has been discussed in the aspect of hydroprocessing, pyrolysis and gasification. Asphaltene was excellent carbon precursor for functional carbon material due to its high aromaticity and carbon yield;several porous carbon nanosheets from asphaltenes that would be prospective electrode materials after being graphitized were shown. Pitch-based carbon fiber derived from coal-derived asphaltenes displayed a tensile strength of 1.0 GPa and elastic modulus of 350 MPa, respectively. These powerful advances will provide asphaltenes promising developments.

THE SEPARATIONS OF ENANTIOMERS OF α—SUBSTITUTED-(2—PYRIDYL)—METHYLAMINES ON A CHIRASIL-VAL CAPILLARY COLUMN

Enantiomers of a-substituted-(2-pyridyl)-methylarfdnes uere separated on SC -7 gas chromatograph with a 20m×0.25mm Chirasil-Val capIlary column,Carrier gas was nitro- gen or hydrogen.The resolution factors(ri.s) were 1.02 to 1.06.Enantiomers of pyridyl anines were separated to and near to base line.

Equivalent materials simulation experimental study on bed separations developing and mining subsidence in constant humidity and constant temperature conditions

A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.

A Non-linear Non-ideal Model of Simulated Moving Bed Chromatography for Chiral Separations

A non-linear non-ideal model, taking into account non-linear competitive isotherms, axial dispersion, film mass transfer, intraparticle diffusion, and port periodic switching, was developed to simulate the dynamics of simulated moving bed chromatography (SMBC). The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of concentration vector. The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of l,1'-bi-2-naphthol enantiomers using SMBC. This model is useful for design, operation, optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects, especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.

High-performance SSZ-13 membranes prepared using ball-milled nanosized seeds for carbon dioxide and nitrogen separations from methane

SSZ-13 membranes with high separation performances were prepared using ball-milled nanosized seeds by once hydrothermal synthesis.Separation performances of SSZ-13 membranes in CO2/CH4 and N2/CH4 mixtures were enhanced after synthesis modification.Single-gas permeances of CO2,N2 and CH4 and ideal selectivities were recorded through SSZ-13 membranes.The effects of temperature,pressure,feed flow rate and humidity on separation performance of the membranes were discussed.Three membranes prepared after synthesis modifications had an average CO2 permeance of 1.16×10-6 mol·(m2·s·Pa)-1(equal to 3554 GPU)with an average CO2/CH4 selectivity of 213 in a 50 vol%/50 vol%CO2/CH4 mixture.It suggests that membrane synthesis has a good reproducible.The membrane also displayed a N2 permeance of 1.07×10-7 mol·(m2·s·Pa)-1(equal to 320 GPU)with a N2/CH4 selectivity of 13 for a 50 vol%/50 vol%N2/CH4 mixture.SSZ-13 membrane displayed stable and good separation performance in the wet CO2/CH4 mixture for a long test period over 100 h at 348 K.The current SSZ-13 membranes show great potentials for the simultaneous removals of CO2 and N2 in natural gas purification as a facile process suitable for industrial application.

Conjugated microporous polymer membranes for chemical separations

Conjugated microporous polymers(CMPs) are a unique class of porous organic materials, which are constructed with π-conjugation structures leading to intrinsic micropores. The CMPs properties such as high surface area, intrinsic and rich micropores, interlocking and rigid structure, extensive π-conjugation and tunable band-gap, chemical and thermal stability, together with tailored functionalities, contribute to its abundant potential for application in fields such as photocatalysis, optoelectronics, energy storage, and chemical sensors. Recently, CMPs have gained importance in the field of membranes for chemical separation. In this review, we briefly discuss the historical development of CMPs, followed by a detailed description of the progress in state-of-the-art design, preparation, and application of CMPs in membranes. Additionally, we provide inference on the future prospects of CMPs as membranes.

Testing the Intermediate-Range Force at Separations Around 50 Meters

We use a LaCoste-Romberg model D gravimeter to measure the gravitational forces at fixed positions when a large cylindrical reservoir is full and when it is empty.The differences determine the intermediate-range force at various separations around 50m to about 0.5%accuracy.

The Enantiomer Separations of Allethrone and Propargyllone Using Two Long Chain Acylated b-Cyclodextrin Derivatives as CGC Capillary Stationary Phases

Using two b-cyclodextrin derivatives (CDs) with long chain of acyl groups as chiral stationary phases (CSPs) of capillary gas chromatography (CGC), the enantiomers of racemic allethrone and propargyllone were well resolved after derived with acetyl chloride. The enantiomer excess values (e.e.%) of 1S-allethrone and 1S-propargyllone were also determined successfully using these CDs.

Computational Studies of DNA Separations in Micro-Fabricated Devices: Review of General Approaches and Recent Applications

DNA separation techniques have drawn attention because of their uses in applications such as gene analysis and manipulation. There have been many studies utilizing micro-fabricated devices for faster and more efficient separations than traditional methods using gel electrophoresis. Although many experimental studies have presented various new devices and methods, computational studies have played a pivotal role in this development by identifying separation mechanisms and by finding optimal designs for efficient separation conditions. The simulation of DNA separation methods in micro-fabricated devices requires the correct capture of the dynamics and the structure of a single polymer molecule that is being affected by an applied flow field or an electric field in complex geometries. In this work, we summarize the polymer models (the bead-spring model, the bead-rod model, the slender-body model, and the touching-bead model) and the methods, focusing on Brownian dynamics simulation, used to calculate inhomogeneous fields taking into consideration complex boundaries (the finite element method, the boundary element method, the lattice-Boltzmann method, and the dissipative particle dynamics simulation). The worm-like chain model (adapted from the bead-spring model) combined with the finite element method has been most commonly used but other models have shown more efficient and accurate results. We also review the applications of these simulation approaches in various separation methods and devices: gel electrophoresis, post arrays, capillary electrophoresis, microchannel flows, entropic traps, nanopores, and rotational flows. As more complicated geometries are involved in new devices, more rigorous models (such as incorporating the hydrodynamic interactions of DNA with solid boundaries) that can correctly capture the dynamic behaviors of DNA in such devices are needed.

Research Progress in the Fabrication of Covalent Organic Framework Membranes for Chemical Separations

Membrane technology has become one of the most promising separation technologies for its energy saving, high separation efficiency, environmental friendliness, and economic feasibility. Covalent organic frameworks(COFs) with intrinsically high porosity, controllable pore size, uniform pore size distribution and long-range ordered channel structure, have emerged as next-generation materials to fabricate advanced separation membranes. This feature article summarizes some latest studies in the development of pure COF membranes in our lab, including their fabrication and applications in chemical separations. Finally, current challenges facing high-performance COF separation membranes are discussed.

Synergistic and Antisynergistic Intracrystalline Diffusional Influences on Mixture Separations in Fixed-Bed Adsorbers

Separations of mixtures in fixed-bed adsorbers are influenced by factors such as(1)selectivity of adsorption,Sads,(2)diffusional time constants,Đi/rc 2,and(3)diffusion selectivity,Đ1/Đ2.In synergistic separations,intracrystalline diffusion of guest molecules serves to enhance the selectivities dictated by thermodynamics of mixture adsorption.In antisynergistic separations,intracrystalline diffusion serves to reverse the hierarchy of selectivities dictated by adsorption equilibrium.For both scenarios,the productivities of the desired product in fixed-bed operations are crucially dependent on diffusional time constants,Đi/rc 2;these need to be sufficiently low in order for diffusional influences to be effective.Also,the ratioĐ1/Đ2 should be large enough for manifestation of synergistic or antisynergistic influence.Both synergistic and antisynergistic separations have two common,distinguishing characteristics.Firstly,for transient uptake within crystals,the more mobile component attains supraequilibrium loadings during the initial stages of the transience.Such overshoots,signifying uphill diffusion,are engendered by the cross-coefficientsΓij(i≠j)of thermodynamic correction factors.Secondly,the component molar loadings,plotted in composition space,follow serpentine equilibration paths.If cross-coefficients are neglected,no overshoots in the loadings of the more mobile component are experienced,and the component loadings follow monotonous equilibration paths.The important takeaway message is that the modeling of mixture separations in fixed-bed adsorbers requires the use of the Maxwell−Stefan equations describing mixture diffusion employing chemical potential gradients as driving forces.

Electrospun Nanofibrous Composite Membranes for Separations

Electrospinning is regarded as an efficient method for directly and continuously fabricating nanofibers.The electrospinning process is relatively simple and convenient to operate and can be used to prepare polymer nanofibers for almost all polymer solutions,melts,emulsions,and suspensions with sufficient viscosity.In addition,inorganic nanofibers can also be prepared via electrospinning by adding small amounts of polymers into the inorganic precursors,which are generally regarded as nonspinnable.The diameter of the electrospun nanofibers can be tuned from tens of nanometers to submicrons by changing the spinning parameters.The nonwoven fabric stacked with electrospun fibers is a porous material with interconnected submicron pores,providing a porosity above 80%.However,limited by the unstable rheological properties of the electrospinning fluid,it is difficult to obtain nanofibers stably and continuously with an average diameter of<100 nm,which narrows the separation applications of the electrospun nanofibrous membranes to only microfiltration,air filtration,or use as membrane substrates.Therefore,to fully take advantage of electrospun nanofibrous membranes in other separation applications,electrospun nanofibrous composite(ENC)membranes were developed to improve and optimize their selectivity,permeability,and other separation performances.The composite membranes not only have all the advantages of single-layered or single-component membranes,but also have more flexibility in the choice of functional components.In this account,we summarize the two combination strategies to design and fabricate ENC membranes.One is based on the component combination,in which functional components are homogeneously or heterogeneously mixed in the fiber matrix or modified on the nanofiber surface.The other one is termed as the interfacial combination,in which functional skin layers are fabricated on the top of the electrospun membranes via interfacial deposition or interfacial polymerization,to construct selective barriers.The specific preparation approaches in the two combination strategies are discussed systematically.Additionally,the structural characteristics and separation performances of ENC membranes fabricated via these approaches are also compared and analyzed to clarify their advantages and range of utilization.Subsequently,the six applications of ENC membranes we focus on are demonstrated,including adsorption,membrane distillation,oil/water emulsion separation,nanofiltration,hemodialysis,and pervaporation.To meet their different requirements for separations,our consideration about the choice of combination strategies,related preparation methods,and functional components are discussed based on typical research cases.In the end,we conclude this account with an overview of the challenges in industrial manufacturing,mechanical strength,and interfacial attachment of ENC membranes and prospect their future developments.

Adverse effects of early-life stress:focus on the rodent neuroendocrine system

Early-life stress is associated with a high prevalence of mental illnesses such as post-traumatic stress disorders,attention-deficit/hyperactivity disorder,schizophrenia,and anxiety or depressive behavior,which constitute major public health problems.In the early stages of brain development after birth,events such as synaptogenesis,neuron maturation,and glial differentiation occur in a highly orchestrated manner,and external stress can cause adverse long-term effects throughout life.Our body utilizes multifaceted mechanisms,including neuroendocrine and neurotransmitter signaling pathways,to appropriately process external stress.Newborn individuals first exposed to early-life stress deploy neurogenesis as a stress-defense mechanism;however,in adulthood,early-life stress induces apoptosis of mature neurons,activation of immune responses,and reduction of neurotrophic factors,leading to anxiety,depression,and cognitive and memory dysfunction.This process involves the hypothalamus-pituitary-adrenal axis and neurotransmitters secreted by the central nervous system,including norepinephrine,dopamine,and serotonin.The rodent early-life stress model is generally used to experimentally assess the effects of stress during neurodevelopment.This paper reviews the use of the early-life stress model and stress response mechanisms of the body and discusses the experimental results regarding how early-life stress mediates stress-related pathways at a high vulnerability of psychiatric disorder in adulthood.

Visual Semantic Segmentation Based on Few/Zero-Shot Learning:An Overview

Visual semantic segmentation aims at separating a visual sample into diverse blocks with specific semantic attributes and identifying the category for each block,and it plays a crucial role in environmental perception.Conventional learning-based visual semantic segmentation approaches count heavily on largescale training data with dense annotations and consistently fail to estimate accurate semantic labels for unseen categories.This obstruction spurs a craze for studying visual semantic segmentation with the assistance of few/zero-shot learning.The emergence and rapid progress of few/zero-shot visual semantic segmentation make it possible to learn unseen categories from a few labeled or even zero-labeled samples,which advances the extension to practical applications.Therefore,this paper focuses on the recently published few/zero-shot visual semantic segmentation methods varying from 2D to 3D space and explores the commonalities and discrepancies of technical settlements under different segmentation circumstances.Specifically,the preliminaries on few/zeroshot visual semantic segmentation,including the problem definitions,typical datasets,and technical remedies,are briefly reviewed and discussed.Moreover,three typical instantiations are involved to uncover the interactions of few/zero-shot learning with visual semantic segmentation,including image semantic segmentation,video object segmentation,and 3D segmentation.Finally,the future challenges of few/zero-shot visual semantic segmentation are discussed.

Direct capture and separation of CO_(2) from air

Direct air capture(DAC)has attracted increasing interest and investment over the past few years.There are a fast-growing number of companies that entered the field and demonstrated DAC carbon removal setups and potential.However,current DAC methods are still based on solid absorbents or alkali solutions approaches which have low capture efficiency and low energy efficiency.This highlight proposed a promising CO_(2) capture technology,an electric energy driven closed-loop system for the direct removal of CO_(2) from ambient air which are based on two individual technologies:Polyam-N-Cu hybrid system promoted CO_(2) capture with ocean as anthropogenic CO_(2) sink and a chloride-mediated electrochemical pH swing system to remove CO_(2) from oceanwater.

Optimal synthesis of heat-integrated distillation configurations using the two-column superstructure

In the realm of the synthesis of heat-integrated distillation configurations,the conventional approach for exploring more heat integration possibilities typically entails the splitting of a single column into a twocolumn configuration.However,this approach frequently necessitates tedious enumeration procedures,resulting in a considerable computational burden.To surmount this formidable challenge,the present study introduces an innovative remedy:The proposition of a superstructure that encompasses both single-column and multiple two-column configurations.Additionally,a simultaneous optimization algorithm is applied to optimize both the process parameters and heat integration structures of the twocolumn configurations.The effectiveness of this approach is demonstrated through a case study focusing on industrial organosilicon separation.The results underscore that the superstructure methodology not only substantially mitigates computational time compared to exhaustive enumeration but also furnishes solutions that exhibit comparable performance.

Stabilizing zinc anode using zeolite imidazole framework functionalized separator for durable aqueous zinc-ion batteries

Aqueous zinc-ion batteries(AZIBs) hold great promise as a viable alternative to lithium-ion batteries owing to their high energy density and environmental friendliness.However,AZIBs are consistently plagued by the formation of zinc dendrites and concurrent side reactions,which significantly diminish their overall service life,In this study,the glass fiber separator(GF) is modified using zeolite imidazole salt framework-8(ZIF-8),enabling the development of efficient AZIBs.ZIF-8,which is abundant in nitrogen content,efficiently regulates the desolvation of [Zn(H_(2)O)_(6)]^(2+) to inhibit hydrogen production.Moreover,it possesses abundant nanochannels that facilitate the uniform deposition of Zn~(2+) via a localized action,thereby hindering the formation of dendrites.The insulating properties of ZIF-8 help prevent Zn^(2+) and water from trapping electron reduction at the layer surface,which reduces corrosion of the zinc anode.Consequently,ZIF-8-GF achieves the even transport of Zn^(2+) and regulates the homogeneous deposition along the Zn(002) crystal surface,thus significantly enhancing the electrochemical performance of the AZIBs,In particular,the Zn|Zn symmetric cell with the ZIF-8-GF separator delivers a stable cycle life at0.5 mA cm^(-2) of 2300 h.The Zn|ZIF-8-GF|MnO_(2) cell exhibits reduced voltage polarization while maintaining a capacity retention rate(93.4%) after 1200 cycles at 1.2 A g^(-1) The unique design of the modified diaphragm provides a new approach to realizing high-performance AZIBs.

Phase separation and transcriptional regulation in cancer development

Liquid-liquid phase separation,a novel biochemical phenomenon,has been increasingly studied for its medical applications.It underlies the formation of membrane-less organelles and is involved in many cellular and biological processes.During transcriptional regulation,dynamic condensates are formed through interactions between transcriptional elements,such as transcription factors,coactivators,and mediators.Cancer is a disease characterized by uncontrolled cell proliferation,but the precise mechanisms underlying tumorigenesis often remain to be elucidated.Emerging evidence has linked abnormal transcriptional condensates to several diseases,especially cancer,implying that phase separation plays an important role in tumorigenesis.Condensates formed by phase separation may have an effect on gene transcription in tumors.In the present review,we focus on the correlation between phase separation and transcriptional regulation,as well as how this phenomenon contributes to cancer development.

Stepped-up development of accelerator mass spectrometry method for the detection of ^(60)Fe with the HI-13 tandem accelerator

The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)Fe.In this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the China Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy degrader.For particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph.Finally,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS system.These results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)Ni.The sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.

The pathogenic mechanism of TAR DNA-binding protein 43(TDP-43)in amyotrophic lateral sclerosis

The onset of amyotrophic lateral sclerosis is usually characterized by focal death of both upper and/or lower motor neurons occurring in the motor cortex,basal ganglia,brainstem,and spinal cord,and commonly involves the muscles of the upper and/or lower extremities,and the muscles of the bulbar and/or respiratory regions.However,as the disease progresses,it affects the adjacent body regions,leading to generalized muscle weakness,occasionally along with memory,cognitive,behavioral,and language impairments;respiratory dysfunction occurs at the final stage of the disease.The disease has a complicated pathophysiology and currently,only riluzole,edaravone,and phenylbutyrate/taurursodiol are licensed to treat amyotrophic lateral sclerosis in many industrialized countries.The TAR DNA-binding protein 43 inclusions are observed in 97%of those diagnosed with amyotrophic lateral sclerosis.This review provides a preliminary overview of the potential effects of TAR DNAbinding protein 43 in the pathogenesis of amyotrophic lateral sclerosis,including the abnormalities in nucleoplasmic transport,RNA function,post-translational modification,liquid-liquid phase separation,stress granules,mitochondrial dysfunction,oxidative stress,axonal transport,protein quality control system,and non-cellular autonomous functions(e.g.,glial cell functions and prion-like propagation).