Double-interpenetrating nanostructured networks of marine polysaccharides possessing properties comparable to synthetic polymers.

Sustainable circular economy requires materials that possess a property profile comparable to synthetic polymers and, additionally, processing and sourcing of raw materials that have a small environmental footprint. Here, we present a paradigm for processing marine biopolymers into materials that possess both elastic and plastic behavior within a single system involving a double-interpenetrating polymer network comprising the elastic phase of dynamic physical cross-links and stress-dissipating ionically cross-linked domains. As a proof of principle, films possessing more than twofold higher elastic modulus, ultimate tensile strength, and yield stress than those of polylactic acid were realized by blending two water-soluble marine polysaccharides, namely alginic acid (Alg) with physically cross-linkable carboxylated agarose (CA) followed by ionic cross-linking with a divalent cation. Dried CAAlg films showed homogeneous nano-micro-scale domains, with yield stress and size of the domains scaling inversely with calcium concentration. Through surface activation/cross-linking using calcium, CAAlg films could be further processed using wet bonding to yield laminated structures with interfacial failure loads (13.2 ± 0.81 N) similar to the ultimate loads of unlaminated films (10.09 ± 1.47 N). Toward the engineering of wood-marine biopolymer composites, an array of lines of CAAlg were printed on wood veneers (panels), dried, and then bonded following activation with calcium to yield fully bonded wood two-ply laminate. The system presented herein provides a blueprint for the adoption of marine algae-derived polysaccharides in the development of sustainable high-performance materials.

3D Printed Solutions for Spheroid Engineering and Cancer Research.

In multicellular organisms, cells are organized in a 3-dimensional framework and this is essential for organogenesis and tissue morphogenesis. Systems to recapitulate 3D cell growth are therefore vital for understanding development and cancer biology. Cells organized in 3D environments can evolve certain phenotypic traits valuable to physiologically relevant models that cannot be accessed in 2D culture. Cellular spheroids constitute an important aspect of in vitro tumor biology and they are usually prepared using the hanging drop method. Here a 3D printed approach is demonstrated to fabricate bespoke hanging drop devices for the culture of tumor cells. The design attributes of the hanging drop device take into account the need for high-throughput, high efficacy in spheroid formation, and automation. Specifically, in this study, custom-fit, modularized hanging drop devices comprising of inserts (Q-serts) were designed and fabricated using fused filament deposition (FFD). The utility of the Q-serts in the engineering of unicellular and multicellular spheroids-synthetic tumor microenvironment mimics (STEMs)-was established using human (cancer) cells. The culture of spheroids was automated using a pipetting robot and bioprinted using a custom bioink based on carboxylated agarose to simulate a tumor microenvironment (TME). The spheroids were characterized using light microscopy and histology. They showed good morphological and structural integrity and had high viability throughout the entire workflow. The systems and workflow presented here represent a user-focused 3D printing-driven spheroid culture platform which can be reliably reproduced in any research environment and scaled to- and on-demand. The standardization of spheroid preparation, handling, and culture should eliminate user-dependent variables, and have a positive impact on translational research to enable direct comparison of scientific findings.

Dechlorination of Excess Trichloroethene by Bimetallic and Sulfidated Nanoscale Zero-Valent Iron.

Nanoscale zerovalent iron (nZVI) likely finds its application in source zone remediation. Two approaches to modify nZVI have been reported: bimetal (Fe-Me) and sulfidated nZVI (S-nZVI). However, previous research has primarily focused on enhancing particle reactivity with these two modifications under more plume-like conditions. In this study, we systematically compared the trichloroethene (TCE) dechlorination pathway, rate, and electron selectivity of Fe-Me (Me: Pd, Ni, Cu, and Ag), S-nZVI, and nZVI with excess TCE simulating source zone conditions. TCE dechlorination on Fe-Me was primarily via hydrogenolysis while that on S-nZVI and nZVI was mainly via ß-elimination. The surface-area normalized TCE reduction rate ( k'SA) of Fe-Pd, S-nZVI, Fe-Ni, Fe-Cu, and Fe-Ag were ∼6800-, 190-, 130-, 20-, and 8-fold greater than nZVI. All bimetallic modification enhanced the competing hydrogen evolution reaction (HER) while sulfidation inhibited HER. Fe-Cu and Fe-Ag negligibly enhanced electron utilization efficiency (εe) while Fe-Pd, Fe-Ni, and S-nZVI dramatically increased εe from 2% to ∼100%, 69%, and 72%, respectively. Adsorbed atomic hydrogen was identified to be responsible for the TCE dechlorination on Fe-Me but not on S-nZVI. The enhanced dechlorination rate along with the reduced HER of S-nZVI can be explained by that FeS conducting major electrons mediated TCE dechlorination while Fe oxides conducting minor electrons mediated HER.

Mechanochemically Sulfidated Microscale Zero Valent Iron: Pathways, Kinetics, Mechanism, and Efficiency of Trichloroethylene Dechlorination.

In water treatment processes that involve contaminant reduction by zerovalent iron (ZVI), reduction of water to dihydrogen is a competing reaction that must be minimized to maximize the efficiency of electron utilization from the ZVI. Sulfidation has recently been shown to decrease H2 formation significantly, such that the overall electron efficiency of (or selectivity for) contaminant reduction can be greatly increased. To date, this work has focused on nanoscale ZVI (nZVI) and solution-phase sulfidation agents (e.g., bisulfide, dithionite or thiosulfate), both of which pose challenges for up-scaling the production of sulfidated ZVI for field applications. To overcome these challenges, we developed a process for sulfidation of microscale ZVI by ball milling ZVI with elemental sulfur. The resulting material (S-mZVIbm) exhibits reduced aggregation, relatively homogeneous distribution of Fe and S throughout the particle (not core-shell structure), enhanced reactivity with trichloroethylene (TCE), less H2 formation, and therefore greatly improved electron efficiency of TCE dechlorination (εe). Under ZVI-limited conditions (initial Fe0/TCE = 1.6 mol/mol), S-mZVIbm gave surface-area normalized reduction rate constants (k'SA) and εe that were ∼2- and 10-fold greater than the unsulfidated ball-milled control (mZVIbm). Under TCE-limited conditions (initial Fe0/TCE = 2000 mol/mol), sulfidation increased kSA and εe ≈ 5- and 50-fold, respectively. The major products from TCE degradation by S-mZVIbm were acetylene, ethene, and ethane, which is consistent with dechlorination by ß-elimination, as is typical of ZVI, iron oxides, and/or sulfides. However, electrochemical characterization shows that the sulfidated material has redox properties intermediate between ZVI and Fe3O4, mostly likely significant coverage of the surface with FeS.

Peroxymonosulfate activation by cobalt-doped ferromanganese magnetic oxides through singlet oxygen and radical pathways for efficient sulfadiazine degradation.

In this paper, cobalt-doped MnFe2O4 (CMFO-0.4) with oxygen vacancies was successfully synthesised by the sol-gel method and applied as a high-performance catalyst for the activation of peroxomonosulfate (PMS). The catalyst showed an excellent catalytic effect for the degradation of sulfadiazine (SDZ) by activated PMS, and the degradation rate can reach 100% in 10 minutes. The effects of different conditions on the degradation of SDZ were investigated, and it was determined that the optimal concentrations of catalyst and PMS were 0.2 g L-1 and 1 mM, respectively, and had good degradation effects in the pH 5-11 range. Free radical quenching experiments, XPS, and electron paramagnetic resonance (EPR) analyses revealed the presence of hydroxyl radicals (˙OH), sulphate radicals (SO4˙-), singlet oxygen (1O2), and superoxide radicals (˙O2 -) in the CMFO-0.4/PMS system, with 1O2 being the main reactive oxygen species (ROS). In addition, CMFO-0.4 has good reusability and adaptability to the presence of other substances.

Construction of high-branched derivatives based on melamine for highly effective defoaming and antifoaming.

Foams can be seen everywhere in human production and life. An uncontrolled foam event usually leads to product losses, equipment damage, and clean-up costs. Defoamer is one of the most effective strategies to eliminate or inhibit foam activities, which has been proved by long-term practices. In this work, we report new molecular defoamers with high-branched structure, which adopts melamine molecule as the parent structure, by incorporating alkyl-isocyanates with different chain lengths into the high-branched melamine derivatives (Hb-MDs) formula to replace the R - NH2 (primary ammonia) on melamine structure. The substitution reaction processes can be readily tuned by varying the molar ratio or alkyl chain length of alkyl-isocyanate, enabling a facile control over the branched degree. The foam tests reveal that the high-branched melamine molecule defoamers exhibited excellent defoaming and anti-foaming properties for four typical foam systems, including an anionic SDBS, cationic DTAB, non-ionic AEO-9, and white cat (BM) detergent, with efficiency close to that of silicone-type LN1414 defoamer and far superior to that of high-carbon alcohol XS-02 defoamer, at the same addition level. Notably, the defoaming or anti-foaming performances of the high-branched melamine molecule defoamers were not always monotonically increased with the branched degree or hydrophobic chain length, but a suitable range needed to be maintained to support a good balance of defoamer structure with foam liquid films. Therefore, it is anticipated that this high-branched design principle could open a new avenue for the construction of molecular defoamers for complex industrial problems.

Structural regulatory mechanism of phosphotungstate acid decorated graphene oxide quantum dots-chitosan aerogel and its application in ciprofloxacin degradation.

Chitosan modified AGQD (amine modified graphene oxide quantum dots) and then combined with H3PW12O40 to obtain CSx@AGQD-HPW12 via facile process and applied for CIP removal through pre-adsorption and photocatalytic processes. The application of chitosan could regulate the morphology and photoelectric properties effectively. CS0.5@AGQD-HPW12 was found to have the optimal CIP removal performance among all the products, the corresponding adsorption removal efficiency and pre-adsorption photocatalysis process were 72.1 % and 98.8 %, respectively. Results of toxicity assessment confirmed photocatalytic degradation process could mitigate the ecotoxicity of CIP effectively. The optimal TOC (total organic carbon) removal efficiency was about 52.1 %. Possible pathways for CIP degradation and reaction mechanism were proposed based on the results of intermediates analysis and trapping experiments. This demonstrated a novel approach to chitosan application and an eco-friendly way to remove CIP by adsorption-photocatalysis process.

Toward 3D Bioprinting of Osseous Tissue of Predefined Shape Using Single-Matrix Cell-Bioink Constructs.

Engineering living bone tissue of defined shape on-demand has remained a challenge. 3D bioprinting (3DBP), a biofabrication process capable of yielding cell constructs of defined shape, when combined with developmental engineering can provide a possible path forward. Through the development of a bioink possessing appropriate rheological properties to carry a high cell load and concurrently yield physically stable structures, printing of stable, cell-laden, single-matrix constructs of anatomical shapes is realized without the need for fugitive or support phases. Using this bioink system, constructs of hypertrophic cartilage of predesigned geometry are engineered in vitro by printing human mesenchymal stromal cells at a high density to drive spontaneous condensation and implanted in nude mice to evoke endochondral ossification. The implanted constructs retain their prescribed shape over a 12-week period and undergo remodeling to yield ossicles of the designed shape with neovascularization. Microcomputed tomography, histological, and immunohistochemistry assessments confirm bone tissue characteristics and the presence of human cells. These results demonstrate the potential of 3DBP to fabricate complex bone tissue for clinical application.

Potential for selective oxidation of aniline in soil washing effluent by active chlorine and testing its practicality.

Recovery of surfactants in the soil washing effluent (SWE) can significantly reduce the cost of the soil washing (SW) technology. This paper consists of two parts experiments. The first part constructed a selective oxidation system of active chlorine by electrochemical technology to treat SWE. Three factors, current density, NaCl concentration and TW 80 to aniline concentration ratio (T/A), were set up for a total of nine sets of experiments after orthogonal design. The results of ANOVA analysis and visual analysis showed that the NaCl concentration greatly affected the aniline removal efficiency (ARE) and the TW 80 retention efficiency (TW 80 RE), and the effects were in opposite directions. The biotoxicity of the SWE decreased as the experiment progressed, and at the end of the experiment, 30%-45% of TW 80 was still present in each set. And the oxidation group quenching experiments determined that the degradation of aniline was mainly contributed by active chlorine. Because active chlorine slowed the loss rate of TW 80, the electrochemical treatment of SWE + soil in-situ sequential batch recirculation washing method was designed, and 50% of aniline in the soil was washed out after 125h. At the end of the experiment, the less biotoxic SWE was collected where no aniline and TW 80 were present, and only small organic acids were present after the GC-MS test. The method has a great potential to be applied as it shows good results in the treatment of soil pollution incidents.

Efficient Electrochemical Oxidation of Chloramphenicol by Novel Reduced TiO2 Nanotube Array Anodes: Kinetics, Reaction Parameters, Degradation Pathway and Biotoxicity Forecast.

The key component of electrochemical advanced oxidation technology are high-efficiency anodes, and highly efficient and simple-to-prepare materials have generated a lot of interest. In this study, novel self-supported Ti3+-doped titanium dioxide nanotube arrays (R-TNTs) anodes were successfully prepared by a two-step anodic oxidation and straightforward electrochemical reduction technique. The electrochemical reduction self-doping treatment produced more Ti3+ sites with stronger absorption in the UV-vis region, a band gap reduction from 2.86 to 2.48 ev, and a significant increase in electron transport rate. The electrochemical degradation effect of R-TNTs electrode on chloramphenicol (CAP) simulated wastewater was investigated. At pH = 5, current density of 8 mA cm-2, electrolyte concentration of 0.1 M sodium sulfate (Na2SO4), initial CAP concentration of 10 mg L-1, CAP degradation efficiency exceeded 95% after 40 min. In addition, molecular probe experiments and electron paramagnetic resonance (EPR) tests revealed that the active species were mainly •OH and SO4-, among which •OH played a major role. The CAP degradation intermediates were discovered using high-performance liquid chromatography-mass spectrometry (HPLC-MS), and three possible degradation mechanisms were postulated. In cycling experiments, the R-TNTs anode demonstrated good stability. The R-TNTs prepared in this paper were an anode electrocatalytic material with high catalytic activity and stability, which could provide a new approach for the preparation of electrochemical anode materials for difficult-to-degrade organic compounds.

Biobridge: An Outlook on Translational Bioinks for 3D Bioprinting.

3D-bioprinting (3DBP) possesses several elements necessary to overcome the deficiencies of conventional tissue engineering, such as defining tissue shape a priori, and serves as a bridge to clinical translation. This transformative potential of 3DBP hinges on the development of the next generation of bioinks that possess attributes for clinical use. Toward this end, in addition to physicochemical characteristics essential for printing, bioinks need to possess proregenerative attributes, while enabling printing of stable structures with a defined biological function that survives implantation and evolves in vivo into functional tissue. With a focus on bioinks for extrusion-based bioprinting, this perspective review advocates a rigorous biology-based approach to engineering bioinks, emphasizing efficiency, reproducibility, and a streamlined translation process that places the clinical endpoint front and center. A blueprint for engineering the next generation of bioinks that satisfy the aforementioned performance criteria for various translational levels (TRL1-5) and a characterization tool kit is presented.

Ti/PbO2 Electrode Efficiency in Catalytic Chloramphenicol Degradation and Its Effect on Antibiotic Resistance Genes.

Livestock farming has led to the rapid accumulation of antibiotic resistance genes in the environment. Chloramphenicol (CAP) was chosen as a model compound to investigate its degradation during electrochemical treatment. Ti/PbO2 electrodes were prepared using electrodeposition. The prepared Ti/PbO2-La electrodes had a denser surface and a more complete PbO2 crystal structure. Ti/PbO2-Co electrodes exhibited improved electrochemical catalytic activity and lifetime in practice. The impact of different conditions on the effectiveness of CAP electrochemical degradation was investigated, and the most favorable conditions were identified (current density: I = 15.0 mA/cm, electrolyte concentration: c = 0.125 mol/L, solution pH = 5). Most importantly, we investigated the effects of the different stages of treatment with CAP solutions on the abundance of resistance genes in natural river substrates (intI1, cmlA, cmle3, and cata2). When CAP was completely degraded (100% TOC removal), no effect on resistance gene abundance was observed in the river substrate; incomplete CAP degradation significantly increased the absolute abundance of resistance genes. This suggests that when treating solutions with antibiotics, they must be completely degraded (100% TOC removal) before discharge into the environment to reduce secondary pollution. This study provides insights into the deep treatment of wastewater containing antibiotics and assesses the environmental impact of the resulting treated wastewater.

A quantitative study of the effects of particle' properties and environmental conditions on the electron efficiency of Pd and sulfidated nanoscale zero-valent irons.

Electron efficiency (or electron selectivity, ɛe) is an important quantitative criterion for zero-valent iron treatment of organohalide contaminated groundwater. The aim of this quantitative study was the systematic exploration and comparison of the effects of the Pd/Fe and S/Fe molar ratios (i.e., [Pd/Fe] and [S/Fe]), trichloroethylene (TCE) concentrations ([TCE]), pH solution, aging time, and water matrices on the ɛe of Pd-nZVI and S-nZVI. To this end, we used TCE as a probe contaminant. The ɛe of Pd-nZVI increased and then decreased with [Pd/Fe], while that of S-nZVI increased with [S/Fe], as more hydrophobic FeS2 was formed on S-nZVI at higher [S/Fe]. The εe of S-nZVI and Pd-nZVI increased with increasing [TCE]. Specifically, the εe of S-nZVI and Pd-nZVI at [TCE] of 200 ppm increased by 24.9 % and 79.3 %, respectively, compared with that at [TCE] of 10 ppm. As the H2 evolution reaction (HER) was more sensitive to surface passivation than TCE dechlorination, the εe of S-nZVI and Pd-nZVI under alkaline conditions was higher than that under basic conditions, and increased by 11.7 % and 37.8 %, respectively, at pH 10 relative to that at pH 6. The εe also increased with the aging time of the S-nZVI and Pd-nZVI particles; the increase was by 27.2 % and 59.6 %, respectively, at aging time of 30 d compared with that of the fresh ones. The ɛe of both particles were higher in artificial groundwater (AGW) than in real groundwater (RGW). For all batch experiments, the εe of S-nZVI increased over the reaction time and tended to outperform that of Pd-nZVI, even though the εe of Pd-nZVI was higher than that of S-nZVI at the initial stage of TCE dechlorination, thereby justifying the longevity of S-nZVI.

Mechanistic role of nitrate anion in TCE dechlorination by ball milled ZVI and sulfidated ZVI: Experimental investigation and theoretical analysis.

Mechanistic role of NO3- in trichloroethylene (TCE) dechlorination by ball milled, micro-scale sulfidated and unsulfidated ZVI (e.g., S-mZVIbm and mZVIbm) was explored through experiments and density functional theory (DFT) calculations. Sulfidation inhibited NO3- reduction by mZVIbm as S weakened its interaction with NO3-. mZVIbm reduced NO3- within 2 h. This just resulted in a short-term electron competition during the dechlorination process by mZVIbm and hardly affected its sluggish dechlorination kinetics (complete TCE dechlorination in 11 d). On the contrary, NO3- suppressed TCE dechlorination by S-mZVIbm. This was attributed to that inhibited NO3- reduction by S-mZVIbm (40 % reduction in 6 h) induced continuous electron competition with TCE during the time span of its dechlorination by S-mZVIbm. NO3- reduction was also observed to facilitate formation/crystallization of Fe3O4 on both ZVI particles, promoting dechlorination by mZVIbm after 4 d while not taking effect to the S-mZVIbm/TCE system, as its dechlorination time was too short for the surface of S-mZVIbm to transform. This observation has important implication on groundwater remediation by ZVI or sulfidated ZVI PRBs under a scenario of upgradient anthropogenic release of NO3-.

Highly efficient and selectivity removal of heavy metal ions using single-layer NaxKyMnO2 nanosheet: A combination of experimental and theoretical study.

Manganese oxides (MnO2) are widely applied in heavy metal ions removal due to their low-cost, environmental-friendly and biocompatibility. However, the adsorption capacity of MnO2 need to be further improved to satisfy the demand of practical application. Herein, a highly dispersed single layer NaxKyMnO2 nanosheet was synthesized by a facile wet-chemical method with sodium dodecyl sulfonate as surfactant. The high surface specific area, excellent dispersibility and abundant oxygen vacancies endowed NaxKyMnO2 nanosheets with potential in heavy metal ions adsorption. The adsorption experiments results showed that NaxKyMnO2 nanosheets possessed high efficiency and selectivity towards lead ion (Pb2+) with a high adsorption capacity of 2091.8 µmol g-1. The NaxKyMnO2 also showed an excellent reusability with the removal rate of 95.4% for Pb2+ even after five cycles. Moreover, both the theoretical calculation and experimental data illustrated that the single layer NaxKyMnO2 nanosheets possess high selectivity to Pb2+ adsorption.

Advanced Bioink for 3D Bioprinting of Complex Free-Standing Structures with High Stiffness.

One of the challenges in 3D-bioprinting is the realization of complex, volumetrically defined structures, that are also anatomically accurate and relevant. Towards this end, in this study we report the development and validation of a carboxylated agarose (CA)-based bioink that is amenable to 3D printing of free-standing structures with high stiffness at physiological temperature using microextrusion printing without the need for a fugitive phase or post-processing or support material (FRESH). By blending CA with negligible amounts of native agarose (NA) a bioink formulation (CANA) which is suitable for printing with nozzles of varying internal diameters under ideal pneumatic pressure was developed. The ability of the CANA ink to exhibit reproducible sol-gel transition at physiological temperature of 37 °C was established through rigorous characterization of the thermal behavior, and rheological properties. Using a customized bioprinter equipped with temperature-controlled nozzle and print bed, high-aspect ratio objects possessing anatomically-relevant curvature and architecture have been printed with high print reproducibility and dimension fidelity. Objects printed with CANA bioink were found to be structurally stable over a wide temperature range of 4 °C to 37 °C, and exhibited robust layer-to-layer bonding and integration, with evenly stratified structures, and a porous interior that is conducive to fluid transport. This exceptional layer-to-layer fusion (bonding) afforded by the CANA bioink during the print obviated the need for post-processing to stabilize printed structures. As a result, this novel CANA bioink is capable of yielding large (5-10 mm tall) free-standing objects ranging from simple tall cylinders, hemispheres, bifurcated 'Y'-shaped and 'S'-shaped hollow tubes, and cylinders with compartments without the need for support and/or a fugitive phase. Studies with human nasal chondrocytes showed that the CANA bioink is amenable to the incorporation of high density of cells (30 million/mL) without impact on printability. Furthermore, printed cells showed high viability and underwent mitosis which is necessary for promoting remodeling processes. The ability to print complex structures with high cell densities, combined with excellent cell and tissue biocompatibility of CA bodes well for the exploitation of CANA bioinks as a versatile 3D-bioprinting platform for the clinical translation of regenerative paradigms.

Effects of non-reducible dissolved solutes on reductive dechlorination of trichloroethylene by ball milled zero valent irons.

Non-reducible solution anions have been well recognized to affect reactivity of ZVI in dechlorinating chlorinated hydrocarbons. However, their effects and corresponding functional mechanisms on electron efficiency (εe) of ZVI remain unclear. In this study, mechanochemically modified microscale sulfidated and unsulfidated ZVI particles (i.e., S-mZVIbm and mZVIbm) and trichloroethylene (TCE) were used as model particles and contaminant to explore such effects. PO43- as a corrosion promoter enhanced initial dechlorination rate by both particles. However, its passivating role as a surface complex agent became significant at the later stage of dechlorination by mZVIbm, while sulfidation alleviated this effect without inhibition of dechlorination. Compared with enhancing dechlorination, PO43- promoted hydrogen evolution reaction (HER) to a higher extent, decreasing εe for both particles by 17-73 %. HCO3- negligibly affected dechlorination by both particles, while elevated HER. Thus, HCO3- [5 mM] decreased εe for S-mZVIbm and mZVIbm by 1.9 % and 22 %. Different from PO43- and HCO3-, Cl- and SO42- showed no significant effects on dechlorination, HER, and therefore εe for both particles. These results imply that even though some co-existing anions (i.e., PO43- and HCO3-) acting as corrosion promoters could improve the dechlorination by ZVIs, they would lead to decreased εe and shortened particle reactive lifetime.

Ultralight and Hydrophobic Palygorskite-based Aerogels with Prominent Thermal Insulation and Flame Retardancy.

Clay-based aerogel is a promising material in the field of thermal insulation and flame retardant, but obtaining clay-based aerogel with high fire resistance, low thermal conductivity, hydrophobicity, and mechanical robustness remains a challenge. In this work, palygorskite-based aerogel was successfully fabricated via combining with a very small proportion of alginate to form a distinctive hierarchically meso-microporous structure. By employing ethanol solution (EA) replacement method and freeze-drying process, the resultant aerogel exhibited ultralow density (0.035-0.052 g/cm3), practical mechanical strengths (0.7-2.1 MPa), and low thermal conductivity of 0.0332-0.165 W/mK (25-1000 °C). The hydrophobicity of aerogel was achieved by simple chemical vapor deposition of methyltrimethoxysilane (MTMS). The Pal-based aerogel showed good performance in both fire resistance with high limiting oxygen index up to 90%, and heat resistance with tolerance of flame up to 1000 °C for 10 min. This renewable Pal-based aerogel with a 3D framework is a promising material to be applied in fields of construction and aerospace for thermal insulation and high fire resistance.

Sulfidation mitigates the passivation of zero valent iron at alkaline pHs: Experimental evidences and mechanism.

Groundwater pH is one of the most important geochemical parameters in controlling the interfacial reactions of zero-valent iron (ZVI) with water and contaminants. Ball milled, microscale ZVI (mZVIbm) efficiently dechlorinated TCE at initial stage (<24 h) at pH 6-7 but got passivated at later stage due to pH rise caused by iron corrosion. At pH > 9, mZVIbm almost completely lost its reactivity. In contrast, ball milled, sulfidated microscale ZVI (S-mZVIbm) didn't experience any reactivity loss during the whole reaction stage across pH 6-10 and could efficiently dechlorinate TCE at pH 10 with a reaction rate of 0.03 h-1. Increasing pH from 6 to 9 also enhanced electron utilization efficiency from 0.95% to 5.3%, and from 3.2% to 22%, for mZVIbm and S-mZVIbm, respectively. SEM images of the reacted particles showed that the corrosion product layer on S-mZVIbm had a puffy/porous structure while that on mZVIbm was dense, which may account for the mitigated passivation of S-mZVIbm under alkaline pHs. Density functional theory calculations show that covered S atoms on the Fe(100) surface weaken the interactions of H2O molecules with Fe surfaces, which renders the sulfidated Fe surface inefficient for H2O dissociation and resistant to surface passivation. The observation from this study provides important implication that natural sulfidation of ZVI may largely contribute to the long-term (>10 years) efficiency of TCE decontamination by permeable reactive barriers with pore water pH above 9.

Reversible physical crosslinking strategy with optimal temperature for 3D bioprinting of human chondrocyte-laden gelatin methacryloyl bioink.

Gelatin methacryloyl is a promising material in tissue engineering and has been widely studied in three-dimensional bioprinting. Although gelatin methacryloyl possesses excellent biocompatibility and tunable mechanical properties, its poor printability/processability has hindered its further applications. In this study, we report a reversible physical crosslinking strategy for precise deposition of human chondrocyte-laden gelatin methacryloyl bioink at low concentration without any sacrificial material by using extrusive three-dimensional bioprinting. The precise printing temperature was determined by the rheological properties of gelatin methacryloyl with temperature. Ten percent (w/v) gelatin methacryloyl was chosen as the printing formula due to highest biocompatibility in three-dimensional cell cultures in gelatin methacryloyl hydrogel disks. Primary human chondrocyte-laden 10% (w/v) gelatin methacryloyl was successfully printed without any construct deformation or collapse and was permanently crosslinked by ultraviolet light. The printed gelatin methacryloyl hydrogel constructs remained stable in long-term culture. Chondrocyte viability and proliferation that were printed under this optimal temperature were better than that of chondrocytes printed under lower temperatures and were similar to that of chondrocytes in the non-printed gelatin methacryloyl hydrogels. The results indicate that with this strategy, 10% (w/v) gelatin methacryloyl bioink presented excellent printability and printing resolution with high cell viability, which appears to be suitable for printing primary human chondrocytes in cartilage biofabrication and can be extensively applied in tissue engineering of other organs or in other biomedical fields.