VALUE DISTRIBUTION PROPERTIES FOR GAUSS MAPS OF IMMERSED HARMONIC SURFACES RAMIFIED OVER HYPERSURFACES

In this paper,we study the value distribution properties of the generalized Gauss maps of weakly complete harmonic surfaces immersed in R^(m),which is the case where the generalized Gauss mapΦis ramified over a family of hypersurfaces{Q_(j)}_(j=1)^(q)in P^(m-1)(C)located in the N-subgeneral position.In addition,we investigate the Gauss curvature estimate for the K-quasiconformal harmonic surfaces immersed in R^(3)whose Gauss maps are ramified over a family of hypersurfaces located in the N-subgeneral position.

Dual cross-linked MXene/cellulose nanofiber/nickel alginate film with improved mechanical properties and electromagnetic interference shielding performance

Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials.Transition metal carbides(MXenes)with excellent conductivity have shown great potential in electromagnetic interference(EMI)shielding materials,while the poor mechanical strength,flexibility,and structural stability greatly limit their further applications.Here,cellulose nanofibers and sodium alginate are incorporated with MXene nanosheets as flexible matrices to construct strong and flexible mussellike layered MXene/Cellulose nanofiber/Sodium Alginate composite films,and nickel ions are further introduced to induce metal coordination crosslinking of alginate units.Benefited from the dual-crosslinked network structure of hydrogen bonding and metal coordination,the tensile strength,Young’s modulus,and toughness of the MXene/cellulose nanofiber/nickel alginate composite film are significantly increased.After subsequent reduction by ascorbic acid,excess nickel ions are reduced to nickel nanoparticles and uniformly dispersed within the highly conductive composite film,which further improved its hysteresis loss effect toward the incident electromagnetic waves.Consequently,the MXene/cellulose nanofiber/nickel alginate-Ni composite film presents a considerably enhanced electromagnetic interference shielding effectiveness(47.17 dB)at a very low thickness of 29μm.This study proposes a feasible dual-crosslinking and subsequent reduction strategy to synergistically enhance the mechanical properties and electromagnetic interference shielding performance of MXene-based composite materials.

Flexible,stretchable and magnetic Fe_(3)O_(4)@Ti_(3)C_(2)Tx/elastomer with supramolecular interfacial crosslinking for enhancing mechanical and electromagnetic interference shielding performance

Electromagnetic interference(EMI)and radiation of electronic devices are ubiquitous,which are potentially hazardous to the normal operation of electronic equipment and human health.MXenes are extremely attractive in the preparation of EMI shielding materials due to their excellent metallic conductivity and tunable surface chemistry.Herein,by virtue of the designed nanostructure and regulation of interface interactions,we fabricated flexible Fe_(3)O_(4)@Ti_(3)C_(2)Tx MXene/3,4-dihydroxyphenylacetic acid(DOPAC)-epoxidized natural rubber(ENR)elastomers(FMDE)with 3D segregated interconnected structures.The elaborately designed metalligand coordination crosslinking between Fe_(3)O_(4)nanoparticles and DOPAC ligand molecules provides strong interfacial interactions,resulting in significantly reinforced mechanical properties.Compared with Ti_(3)C_(2)Tx/ENR elastomers,the maximum tensile strength and toughness of FMDE are elevadted by~306%and 475%,respectively.Moreover,the 3D segregated conductive network constructed by Fe_(3)O_(4)@Ti_(3)C_(2)Tx nanoflakes resulted from volume exclusion effect of ENR latex and the introduction of magnetic Fe_(3)O_(4)nanoparticles with enhanced electromagnetic wave absorption greatly improved the EMI shielding performance of FMDE,exhibiting an excellent EMI shielding effectiveness of up to 58 dB in the X band(8.2–12.4 GHz)and stable EMI shielding capability during repeated deformations.This work provides a promising strategy for the design and manufacture of novel flexible EMI shielding materials.

Shear stress-induced delamination method for the mass production of Ti_(3)C_(2)Tx MXene nanosheets

MXene nanosheets are considered advantageous for functional materials,but current delamination methods to prepare MXene nanosheets have many limitations including high cost,small production scale,low efficiency,and deteriorated structure integrity of obtained nanosheets.Here,we propose a simple,efficient,and scalable shear stress-induced delamination(SSID)strategy to boost the production of single-/few-layered Ti_(3)C_(2)T_(x) MXene nanosheets.Molecular dynamics simulation indicates that the pan mill-type grinding discs create a strong hydrodynamic flow field,which exerts gigantic shear stress to substantially delaminate the multilayered MXene stacks into homogeneously dispersed MXene nanosheets.Furthermore,shear stress generated from vigorous water flow has limited fragmentation effect,ensuring large lateral size and good structure integrity to the obtained MXene nanosheets as evidenced by the morphological and structural characterizations.Compared to conventional delamination methods,this novel SSID strategy exhibits great advantages in terms of efficiency,scalability and the properties of resultant MXene nanosheets,which opens up great opportunity for the scalable production and commercialization of high-performance MXene-based materials.