Experiments on Large-Diameter Welded Hollow Spherical Joint

We experimented on welded hollow spherical joint of a stadium steel roof to investigate the stress and strain distributions on the surface of the joint and determine the ultimate bearing capacity. Then, finite element analysis was made to experimental results. When the test load was 140% of the design load, the stress at the bottom of the fourth wimble pipe reached the yield point. The experimental results agree with the analytical results well.

Deformation Analysis and Optimization on Hollow Spherical Rotor in Electrostactically Suspended Gyroscope

Non-spherical of rotor was described with solution method. Electrostatically suspended gyroscope＇s hollow spherical rotor＇s structure was presented. The simulative analysis of static deformation, dynamic deformation and synthesize deformation of rotor under different working conditions using the finite element software were carried out. Its deformation law and volume were obtained. The structural parameters of the rotor were optimized. The value of pressure required when the rotor was machined was calculated. The analysis has important theoretical reference value to the design for hollow spherical rotor in electrostatically suspended gyroscope.

Preparation of hollow spherical covalent organic frameworks via Oswald ripening under ambient conditions for immobilizing enzymes with improved catalytic performance

The hollow spherical covalent organic frameworks(COFs)have a wide application prospect thanks to their special structures.However,the controllable synthesis of uniform and stable hollow COFs is still a challenge.We herein propose a self-templated method for the preparation of hollow COFs through the Ostwald ripening mechanism under ambient conditions,which avoids most disadvantages of the commonly used hard-templating and soft-templating methods.A detailed time-dependent study reveals that the COFs are transformed from initial spheres to hollow spheres because of the inside-out Ostwald ripening process.The obtained hollow spherical COFs have high crystallinity,specific surface area(2,036 m^(2)·g^(−1)),stability,and single-batch yield.Thanks to unique hollow structure,clear through holes,and hydrophobic pore environment of the hollow spherical COFs,the obtained immobilized lipase(BCL@H-COF-OMe)exhibits higher thermostability,polar organic solvent tolerance,and reusability.The BCL@H-COF-OMe also shows higher catalytic performance than the lipase immobilized on non-hollow COF and free lipase in the kinetic resolution of secondary alcohols.This study provides a simple approach for the preparation of hollow spherical COFs,and will promote the valuable research of COFs in the field of biocatalysis.

Development of covalent-organic frameworks derived hierarchical porous hollow carbon spheres based LiOH composites for thermochemical heat storage

Under the joint assistance of its excellent storage strength, accessible long storage lifespan, and high heat utilization efficiency, salt hydrate-based thermochemical heat storage(THS) materials give renewable energy an important outlet to alleviate the pressure of underutilization. Herein, an activated hollow spherical carbon(AHSC) with hierarchical porous architectures converted from covalent-organic frameworks(COFs) is constructed and utilized as the supporting matrix for Li OH.THS composite material for the first time. The obtained Li/AHSC_(3) composites have distinguished hydration performance while manifesting impressive storage ability up to 1916.4 k J kg^(-1)with low operating temperature stemming from the collective effect of the void spherical framework, multimodal porosity, and high surface area of AHSC3. And the Li/AHSC3-40 composite with evidently progressed thermal conductivity is capable of realizing 94.5% heat preservation after twenty-five adsorption-desorption cycles, exhibiting its eminent cyclability and great heat transfer performance. This study not only brings new hope for overcoming the underutilization of low-grade heat but also may enlighten new ideas for enriching the application scenarios of COFs-derived carbonaceous materials.

Synthesis and modification of spherical/hollow metal-organic frameworks for efficient extraction of sulfonamides in aqueous environments

In this study,two novel spherical/hollow metal-organic frameworks were successfully synthesized,and further modified by a mild non-covalent modification strategy with dopamine and 1,4-benzenedithiol(BDT)as polymeric monomers to obtain pB DT@PDA-Ni-MOF and p BDT@PDA-Ni/Co-MOF,respectively.The results showed that the above MOFs possessed extremely fast adsorption rates and ideal adsorption capacities for sulfonamides(SAs)and the modified MOFs exhibited enhanced adsorption capacities for SAs owing to a large number of additional functional groups.Then,benefit of their regular morphology and size,a facile syringe-assisted dispersive solid phase extraction(S-DSPE)method was developed for efficient detection of SAs,which will provide a powerful tool for monitoring trace level of SAs in aqueous environment.

Structure and Mechanical Properties of Ni-based Porous Superalloy

The porous superalloy materials with hollow spherical and oriented linear pores were fabricated by means of powder metallurgy using Ni-based superalloy powders. Structure observation revealed that the pores of the porous material exhibited uniform distribution and the pores were of the same size in principle. The sintering necks created between adjacent particles on metal skeleton after sintering. The porosity of the porous material increased with increasing the addition of pore forming agent, and the hollow spherical porous material with a porosity of 81.62% were obtained when the addition of pore forming agent was 40%. The compression test indicated that this kind of materials possesses excellent energy absorption capability, and the compression resistance decreased with the increasing of porosity and pore size.

MORPHOLOGICAL AND MICROSTRUCTURAL CHANGES DURING THE HEATING OF SPHERICAL CALCIUM ORTHOPHOSPHATE AGGLOMERATES PREPARED BY SPRAY PYROLYSIS

The microstructural changes taking place during heating of calcium orthophosphate (Ca3(PO4)2) agglom- erates were examined in this study. The starting powder was prepared by the spray-pyrolysis of calcium phosphate (Ca/P ratio=1.50) solution containing 1.8 mol·L-1 Ca(NO3)2, 1.2 mol·L-1 (NH4)2HPO4 and concentrated HNO3 at 600 C, using an o air-liquid nozzle. The spray-pyrolyzed powder was found to be composed of dense spherical agglomerates with a mean diameter of 1.3 μm. This powder was further heat-treated at a temperature between 800 and 1400 C for 10 min. When o the spray-pyrolyzed powder was heated up to 900 C, only β-Ca3(PO4)2 was detected, and the mean pore size of the o spherical agglomerates increased via the (i) elimination of residual water and nitrates, (ii) rearrangement of primary par- ticles within the agglomerates, (iii) coalescence of small pores (below 0.1 μm), and (iv) coalescence of agglomerates with diameters below 1 μm into the larger agglomerates. Among the heat-treated powders, pore sizes within the spherical agglomerates were observed to be the largest (mean diameter: 1.8 μm) for the powder heat-treated at 900 C for 10 min. o With an increase in heat-treatment temperature up to 1000 C, the spherical agglomerates were composed of dense o shells. Upon further heating up to 1400 C, the hollow spherical agglomerates collapsed as a result of sintering via the o phase transformation from β- to α-Ca3(PO4)2 (1150 C), thus leading to the formation of a three-dimensional porous net- o work.

MOF-derived Hierarchical Hollow NiRu-C Nanohybrid for Efficient Hydrogen Evolution Reaction

Designing efficient electrocatalysts for efficient hydrogen evolution is extremely desired but challenging. Herein, we report a facile MOF-assisted strategy to synthesize the hierarchical hollow spherical NiRu-C nanohybrid with closely packed rod-like bulges on the surface. Benefited from the more exposed active sites of NiRu-C nanohybrid and the efficient electron/mass transport in its unique hierarchical hollow spherical nanostructure, the optimized nanohybrid showed excellent performance for alkaline hydrogen evolution with ultralow overpotentials, which are much superior to those of Pt/C and the overwhelming majority of reported electrocatalysts. The interpretation of the reaction mechanism was further discussed with DFT calculations. Our research may provide a guidance for the development of advanced electrocatalysts with controlled morphology and excellent performance for future energy applications.

Preparation,Structure and Mechanical Properties of Nickel Based Porous Spherical Superalloy

The porous superalloy materials with hollow spherical pores were fabricated by using metal powder sintering process. The scanning electron microscope （SEM） observation was applied to the test samples and it revealed that the pores of the porous material exhibited a uniform distribution and the apertures were of same size in principle. The sintering necks appeared between adjacent particles on metal skeleton after sintering. The mechanical properties of the test samples were analyzed and the result showed that this kind of materials possessed excellent energy absorption capability, and the compression resistance decreased with increasing the porosity and aperture.

Ultra-lightweight ceramic scaffolds with simultaneous improvement of pore interconnectivity and mechanical strength

The high porosity and interconnectivity of scaffolds are critical for nutrient transmission in bone tis-sue engineering but usually lead to poor mechanical properties.Herein,a novel method that combines acid etching(AE)with selective laser sintering(SLS)and reaction bonding(RB)of Al particles is pro-posed to realize highly improved porosity,interconnectivity,mechanical strength,and in vitro bioactivity in 3D Al_(2)O_(3) scaffolds.By controlling the oxidation and etching behaviors of Al particles,a tunable hol-low spherical feature can be obtained,which brings about the distinction in compressive response and fracture path.The prevention of microcrack propagation on the in situ formed hollow spheres results in unique near elastic buckling rather than traditional brittle fracture,allowing an unparalleled compressive strength of 3.72±0.17 MPa at a high porosity of 87.7%±0.4%and pore interconnectivity of 94.7%±0.4%.Furthermore,scaffolds with an optimized pore structure and superhydrophilic surface show excellent cell proliferation and adhesion properties.Our findings offer a promising strategy for the coexistence of out-standing mechanical and biological properties,with great potential for tissue engineering applications.