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As the most widely used additive manufacturing technology, Fused Filament Fabrication 3D printing technology has attracted more and more attention and research on its mechanical properties. In this paper, Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS) and Poly Ether-Ether Ketone (PEEK) materials are selected as the research objects to study the material correlation of the compression performance of the printed parts in different build orientations. Under the premise of ensuring that the other process parameters are basically the same, the comparison test results show that, the compressive strength of PLA and PEEK in build orientation Z1 is larger than that in build orientation Z2. On the contrary, the compressive strength of ABS in build orientation Z2 is larger, which reflects the material correlation of mechanical properties. The cone beam Computed Tomography nondestructive testing and Field Emission Scanning Electron Microscope are used to scan the test pieces before and after the experiment. According to the analysis of the testing images, the interlaminar pores caused in the printing process are the main reasons for the different performance responses and structural damage of the test pieces under the compression load.

Recently, 3D cryogels with the interconnected macropore structure have gained great attention owing to their immense application potential in wastewater cleanup. Here, we fabricated a pure poly(vinyl imidazole) cryogel through improved cryogelation method, adding the pre-freezing–thawing step, which reduced the temperature difference between the different positions of the precursor solution during reaction. Compression experiments showed that the prepared 3D cryogel featured a robust underwater elastic performance. The adsorption capacity of Cu(II), Ni(II), Zn(II), Co(II), Pb(II), and Cd(II) ions from aqueous solutions by the poly(vinyl imidazole) cryogel was explored. The results showed the specific adsorption of Cu(II), in which the adsorption capacity and removal efficiency reached 148 mg/g and 99.99%, respectively. The adsorption capacity was 58 times higher than that of the reported poly(vinyl imidazole) cryogel which was prepared using hydroxyethyl methacrylate as the comonomer frameworks. In the reusability studies, the cryogel exhibited accumulating Cu(II) ions performance and excellent regeneration capability, making it a promising adsorbent for Cu(II) removal.

The data obtained during the measurement of optical 3D topography will directly affect the final measurement result. It is aimed at the noise and invalid measurement points that are difficult to identify and remove due to the hardware assembly error of the measurement system and the specular reflection during the structured light measurement. This article proposes a noise recognition and removal method based on the intermediate parameters of image processing. This method can make the measurement of point cloud data more accurate and reliable, and also avoid the more complicated and time-consuming point cloud data processing process. At the end of this article, experiments on noise identification and removal of large-scale point cloud data obtained by line laser scanning of engine blades were carried out. Experiments prove that this method can remove noise and invalid points in the point cloud under the premise of ensuring a certain accuracy, especially the measurement accuracy of the leaf edge.

Construction of monolithic cryogels that can efficiently adsorb proteins is of great significance in biotechnological and pharmaceutical industries. Herein, a novel approach is presented to fabricate microfibrillated cellulose (MFC)/sodium alginate (SA) cryogels by using freezing-induced oxa-Michael reaction at −12 °C. Thanks to the controllable reactiveness of divinyl sulfone (DVS), cryo-concentrated pH increase activates the oxa-Michael reaction between DVS and hydroxyl groups of MFCs and SAs. The obtained composite cryogel exhibits outstanding underwater shape recovery and excellent fatigue resistance. Moreover, the MFC/SAs reveal a high lysozyme adsorption capacity of 294.12 mg/g, surpassing most of absorbent materials previously reported. Furthermore, the cryogel-packed column can purify lysozyme continuously from chicken egg white, highlighting its outstanding practical application performance. Reuse experiments indicated that over 90% of lysozyme extraction capacity was retained after 6 cycles. This work provides a new avenue to design and develop next-generation chromatographic media of natural polysaccharide-based cryogel for protein purification.

Coal gangue (CG) as mineral waste was properly treated and applied as the filter media in permeable pavement systems due to its good sorption ability and mechanical strength. Batch experiments show the maximum adsorption capacity of calcined CG to phosphorus could reach 2.63 mg/g. To evaluate the removal effect of typical runoff pollutants including chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and ammonia (NH4+-N), the gravel and sand in a traditional pavement system were replaced by CG respectively. The leaching behavior of the four pollutants in CG modified systems is limited and comparable with traditional system, indicating pretreated CG as filler would not cause environmental risk. CG-based pavement systems improved the removal efficiency of the four pollutants especially for TP. The removal mechanisms including interception, adsorption and microorganism degradation. The removal rates of COD, NH4+-N and TN by CG modified and traditional systems decreased with rainfall duration, while it is not obviously changed with rainfall recurrence period and drying period. Overall, the permeable pavement with CG layers that replaced both sand and gravel layers show best removal efficiency of all pollutants investigated especially for TP (>95%). This study provides a new way for CG utilization and gives the reference for the process design of permeable pavement.

Interconnected macro-porous cryogels with robust and pore-tunable structures have been fabricated using chemically crosslinked microfibrillated cellulose (MFC). Periodate oxidation was initially conducted to introduce aldehyde groups into the MFC surface, followed by the freeze-induced chemical crosslinking via the formation of hemiacetal bonds between aldehyde and hydroxyl at −12 °C. The cryogels with pore-tunable structures and sharply enhanced mechanical strengths were finally achieved by re-assembly of MFCs through soaking in NaIO4 solution. Furthermore, the MFC cryogels were post-crosslinked by polyethyleneimine (PEI), bestowing the cryogels with the capability of adsorbing anionic dyes. The stress of the PEI-MFC cryogel at the 80% strain was determined to be 304.5 kPa, which is the maximum value for the nanocellulose-based cryogels reported so far. Finally, the adsorption performances of PEI-MFC cryogels for methyl orange (MO) were evaluated. Maximum adsorption capacity of 500 mg/g could be obtained by the Langmuir model, outperforming that of previous absorbent materials. Reuse experiments indicated that over 90% of adsorption capacity was retained after 6 cycles. Continuous clean-up experiments demonstrated excellent MO removal abilities of the PEI-MFC cryogel. This study shows that the novel, green strategy to fabricate the robust cryogel extends the practical applications of nanocellulose adsorbents for environmental remediation.

Environmental risk of heavy metals and metalloids in athletic fields has raised people’s attention in the recent years. Seven trace elements, including metals and metalloids, were detected in the runoff of five typical athletic fields in the university campus under three rainfall events. Except for Cr, the total concentrations of Zn, Pb, Cu, Mn, Cd, and As in artificial turf runoff are the highest among five athletic fields, followed by that of plastic runway. The concentration and first flush effect of trace elements are followed in the order of 1st > 2nd > 3rd rainfall events. The strongest correlations between metals and metalloids were observed in the tennis court runoff, while the artificial turf shows the least. The release of trace elements could be directly from the surface materials and particles on the athletic field and influenced by the comprehensive factors including surface materials, rainfall events, and pollutant characters. Pollution risk assessment shows that the pollution extent of the five types of athletic field is at least “moderate” and follows the order of artificial turf > basketball court > plastic runway > badminton court > tennis court. Pb shows the highest pollution level, while Cr shows the highest healthy risk. The results can provide a theoretical basis for runoff pollution control and safety use of athletic fields.