The bonded-particle model(BPM)is commonly used in the numerical analysis of ore samples.To improve the accuracy of simulating the mechanical process of ore process of ore crushing in a crusher,the parameters of the BPM for the ore must be calibrated.In this study,a calibration method was proposed for the scientific determination of the parameters of the BPM for ore undergoing uniaxial compression.First,physical tests and simulations were conducted to determine the mechanical response(uniaxial compressive strength and macroscopic stiffness)of ore during uniaxial compression.Then,the sensitivity of the mechanical response to the values of microscopic parameters was tested using a Plackett-Burman design.Next,the microscopic parameters with the greatest impact on the response were identified,and the range of parameters that met the target response was determined using a steepest ascent design;Second,a second-order model of the mechanical response was established using the sensitive parameters by combining a Box-Behnken design with response surface methodology to obtain the optimal BPM parameters.Simulation tests showed that the normal stiffness per unit area,critical shear stress,and bonded disk radius had significant effects on the uniaxial compressive strength(UCS)and macroscopic stiffness(MS).To verify the validity of the proposed calibration method,laboratory tests were conducted.The consistency of the simulation results with experimental results indicated that response surface methodology with the Plackett-Burman design,steepest ascent design,and Box-Behnken design can be an effective method for calibrating the BPM of ores.
Shuwei WuGuoqiang WangLongfei FanWei GuanJianbo GuoZhengbin LiuYukuan Wang
Hydrogen-bonded organic frameworks(HOFs)are a recent class of porous materials that have garnered considerable research interest owing to their distinctive characteristics.HOFs can be constructed through judicious selection of H-bonding motifs,which are further enforced by other weak intermolecular interactions such asπ–πstacking,van der Waals forces,and framework interpenetration.Taking advantage of these interactions,we can expand the functional field of HOFs by introducing active molecules.Recently,researchers have made substantial advancements in using HOFs for chemical sensing,catalysis,proton conduction,biological applications,and others.The low bonding energy of H-bonds allows for precise control over the concentration of ligands in solvents,forming diverse HOF structures.These varied structures offer significant advantages for producing HOFs with photo-responsive and electro-responsive properties.However,the presence of H-bonds in HOFs results in their inherent lower stability compared to metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)formed via coordination and covalent bonds,respectively.As a result,the pursuit of stable and innovative HOF materials with novel functional sites remains an ongoing challenge.This review provides an overview of recent research progress in the development of new strategies for stable HOF synthesis and applications of HOFs with stimuli-responsive properties.We first classified all synthetic methods reported to date and discussed the stable HOFs synthesized,as well as their unique properties and applications.In addition,we summarized the applications of HOFs utilizing their synergistic responses to external stimuli,including photo,electrical,pressure,and chemical stimuli.We systematically reviewed stable HOF synthesis and applications,which may lead to a deeper understanding of the structure–activity relationship for these materials and guide future HOF design.
Ying HouXin-Song HuangSheng-Hao GongChen LiuYangyang LiuTian-Fu Liu
Safe confinement of fission iodine isotopes for long-term radioactive waste disposal remains a formidable challenge,as conventional sorbents provide inherently weak iodine-host interactions.We report here a novel halogen bond(X-bond)directed strategy to sequester volatile iodine in hydrogen-bonded(H-bonded)frameworks with unprecedented stability.Charge-assisted Hbonded frameworks bearing open halide sites are developed,showing distinctive iodine encapsulation behaviors without compromising the crystallinity.Direct crystallographic evidence indicates the formation of X-bonds,i.e.,I–I···Cl^(−) and I–I···Br^(−),within the confined pore channels.Unusual polyhalogen anions,i.e.,[I_(2)Cl_(2)]^(2−)and[I_(2)Br_(2)]^(2−),sustained in H-bonded frameworks are identified for the first time.The X-bond reinforced host-guest interaction affords robust iodine trapping without leaking out even at elevated temperatures up to 180℃.By integrating the halogen-bond chemistry with H-bonded frameworks,this study offers fresh concepts for developing effective host reservoirs to secure fission iodine isotopes from spent fuel reprocessing off-gases.
Yi XiePengling HuangQiang GaoShiyu WangJianchen WangGang Ye
To develop porous organic frameworks,precise control of the stacking manner of two-dimensional porous motifs and structural characterization of the resultant framework are important.From these points of view,porous molecular crystals formed through reversible intermolecular hydrogen bonds,such as;hydrogen-bonded organic frameworks(HOFs),can provide deep insight because of their high crystallinity,affording single-crystalline X-ray diffraction analysis.In this study,we demonstrate that the stacking manner of hydrogen-bonded hexagonal network(HexNet)sheets can be controlled by synchronizing a homological triangular macrocyclic tecton and a hydrogen-bonded cyclic supramolecular synthon called the phenylene triangle.A structure of the resultant HOF was crystallographically characterized and revealed to have a large channel aperture of 2.4 nm.The HOF also shows thermal stability up to 290°C,which is higher than that of the conventional HexNet frameworks.
Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concerns impede its practical viability.This work provides a hydrogen-bonded organic framework(HOF)modification strategy to simultaneously improve the electrochemical performance,thermal stability and incombustibility of separator.Melamine cyanurate(MCA),as a low-cost and reliable flame-retardant HOF,was implemented in the separator modification layer,which can prevent the battery short circuit even at a high temperature.In addition,the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte.The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3%after 300 cycles at 1.0 C.Collectively,the usage of MCA in lithium-ion batteries(LIBs)affords a simple,low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.
Flexible-robust hydrogen-bonded organic frameworks(HOFs)are attracting increasing interest due to their excellent separation performance for important industrial gases,but the construction remains challenging.Herein,a sticked-layer strategy is first proposed to construct a flexible-robust HOF,HOFFJU-8,from a donor(D)–π–acceptor(A)molecule 4,4′,4″,4‴-(pyrrolo[3,2-b]pyrrole-1,2,4,5-tetrayl)tetrabenzonitrile(DP-4CN).HOF-FJU-8 is amicroporous three-dimensional framework composed of two kinds of DP-4CN molecules,one acting as building units for the two-dimensional layer via C≡N···H–C hydrogen bond dimers and another as the sticks to link the layers along channels through D–Aπ···πinteractions.The activated framework HOF-FJU-8a possesses flexible-robust pore characteristics,as determined by the gas adsorption and in situ gas-loaded powder X-ray diffraction.HOF-FJU-8a exhibits adaptive adsorption and stronger binding affinity to C_(2)H_(2)rather than CO_(2)due to the flexible-robust nature,which can effectively separate acetylene and carbon dioxide mixtures.
We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of a slider on the surface of bilayer graphene using molecular dynamics.The results show that the presence of the interlayer covalent bonds due to the local sp^(3) hybridization of carbon atoms in the bilayer graphene seriously reduces the frictional coefficient of the bilayer graphene surface to 30%,depending on the coverage of interlayer sp^(3) bonds and normal loads.For a certain coverage of interlayer sp3bonds,when the normal load of the slider reaches a certain value,the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider.Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds,which may be useful for applications of friction related graphene based nanodevices.
Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer(LCPs)for optoelectronic devices.Singlet excitons are easily trapped by the intrinsically defect structures.Herein,we set a polyfluorenol(PPFOH)as an example to systematically investigate its photophysical behavior to check the role of defect structures in LCPs.According to time-resolved photoluminescence analysis,the feature emission peaks from individual chain of PPFOH in diluted DMF solution is effectively avoided the influence of fluorenone formation,but the residual green-band emission at 550nm is easily observed in the PL spectra of PPFOH dilute toluene solution obtained delay 1.5 ns,confirmed the formation of“guest”physical aggregation-induced defect structure.Remarkably,efficient and ultrafast energy transfer from individual chain to defect structure is observed in PPFOH films.Interestingly,the efficient energy transfer happened for the film obtained from DMF solution(200 ps)than those of toluene ones(600 ps).Meanwhile,compared to relatively stable green-band emission in PPFOH film from toluene solution,red-shifted emission peak(11 nm)of PPFOH film from DMF solutions exposed to saturated DNT vapor also confirmed their different aggregation-induced green-band emission.Therefore,this aggregation defect structures are influenced on the photophysical property of LCPs in solid states.
