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•The presence of COO–-Zn2+ between CNFs and ZnIn2S4 leads to the 3D netted structure.•The photocatalytic activity of Cr(VI) reduction highly enhanced over CNFs/ZnIn2S4.•The 3D netted ...structure strengthen the light via light penetration and scattering.•The enhanced photocatalytic activities are caused by the unique 3D netted structure.
High-performance three-dimensional (3D) netted ZnIn2S4 was achieved by the ionic connection between COO– of TEMPO-cellulose nanofibrils (CNFs) and Zn2+ of ZnIn2S4 via a facile one pot synthesis. The newly-formed COO–-Zn2+ bond connection was clearly confirmed by the shifts of relative peaks in their Fourier transform infrared and X-ray photoelectron spectroscopy spectra. The prepared CNFs/ZnIn2S4 composites exhibited dramatic enhancement of photocatalytic activity for Cr(VI) reduction under visible-light irradiation compared to that of pure ZnIn2S4 and CNFs. Particularly, the photocatalytic efficiency of C/ZIS-0.4 (40 wt% CNFs to ZnIn2S4) is 2.1 times as high as that of pristine ZnIn2S4 (CNFs have almost no photocatalytic activity). On the basis of all experimental results, it can be deduced that the specific 3D netted structure of CNFs/ZnIn2S4 could provide much efficient light-harvesting triggered by light penetration and scattering, abundant exposed active sites, decreased charge transport distance and good hydrophilia, which are responsible for its boosted photocatalytic activity. This study could enlighten people for developing high-efficiency photocatalysts via morphologies design guided by bond connection.
Microreactors offer excellent mass and heat transfer performance for extraction and multiphase reactions. They provide a powerful tool for process intensification and micro scale processing. This ...paper reviews the structures of microreactors and units, and their applications on the synthesis of nanoparticles, organics, polymers and biosubstances. The structural evolution and properties of the commercialized and lab-made microreactors are introduced in detail. Recent developments of the fabrication, structures and applications of micro-structured reactors are highlighted. The promising direction in science and technology for future microreaction technology is also discussed.
Interconnected hierarchical porous carbons were synthesized via KOH-assisted hydrothermal pretreatment and carbonization of wood sawdust. KOH-assisted hydrothermal treatment can remove the lignin ...from sawdust and on the other hand, the presence of KOH facilitates the creation of macro and mesopores during the carbonization. Base-assisted hydrothermal treating time plays an important role in determining the pore structure of carbons, thus affecting their electrochemical performance. The resulting porous carbons show the highest specific capacitance of 303 F g−1 in a current density of 1 A g−1, high energy density of 17.75 W h kg−1 at a power density of 436 W kg−1, and an outstanding cycling stability. As a facile synthesis route for porous carbons from wood sawdust, such method has the potential to be directly used for industrial production, and the efficient uses of wood residue are important for sustainable development.
•KOH could degrade lignin and facilitate the formation of hierarchical pores.•The honeycomb-like porous carbon could be achieved after hydrothermal treatment.•The degradation of lignin has a positive effect to the creation of macro and mesopores.•The sawdust derived porous carbon shows the highest specific capacitance of 303 F g−1.
ZIF-8@cellulose nanofiber (ZIF-8@CNF) composite membranes were prepared via in-situ growing ZIF-8 crystals on cellulose nanofibers (CNFs) and vacuum filtration. Owning to the electrostatic forces ...between –COO- of CNFs and Zn2+ of ZIF-8, ZIF-8 crystals were anchored homogenously on CNFs. With ZIF-8 loading increased to sufficiently high, the intrinsic selectivity of ZIF-8 played an important role for gas separation. As a result, the optimum separation performance is achieved over ZIF-8@CNF-70 composite membrane with CO2 permeability of 550 Barrer and CO2/N2 and CO2/CH4 ideal selectivity of 45.5 and 36.2, respectively.
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•ZIF-8@CNF composite was prepared via in-situ growing ZIF-8 crystals on CNFs.•ZIF-8 crystals anchored homogenously in CNFs matrix with the electrostatic forces.•ZIF-8 loading was increased to sufficiently high in composite membrane.•The intrinsic selectivity of ZIF-8 played an important role for gas separation.
In this note we develop an extension of the Marčenko–Pastur theorem to time series model with temporal correlations. The limiting spectral distribution (LSD) of the sample covariance matrix is ...characterised by an explicit equation for its Stieltjes transform depending on the spectral density of the time series. A numerical algorithm is then given to compute the density functions of these LSD’s.
Floatable low-density millimetre-sized hollow carbon beads were prepared by a phase inversion method, and they were used to promote water evaporation under simulated sunlight. Hollow carbon beads ...with 1.5mm diameter achieved an evaporation rate of 1.28Lm−2h−1 that was around 237% of the rate attained without carbon beads when 714gm−2 (0.5g) of carbon beads were present. This significant enhancement of water evaporation rate is owing to the dramatic increase of the water surface temperature, which is brought about by the light-absorbing property of the floating hollow carbon beads. In addition, a good recyclability was also demonstrated. In general, these millimetre-sized hollow carbon beads accelerate the water evaporation process, making the collection and recycle process easier to suit the practical application.
•Low density and hydrophobic hollow carbon beads are floatable on the water surface.•Simple phase inversion method was used to prepare the carbon bead precursor.•Hollow carbon beads can accelerate the water evaporation process by a factor of 2.37.•Water surface temperature increased significantly in the solar evaporation process.•A good recyclability of hollow carbon beads was demonstrated.
•ZIF-8 prepared from stoichiometric metal and ligand aqueous solutions.•The role of ammonium hydroxide for ZIF-8 preparation was discussed.•Concentrated precursor solution was used to prepare ...ZIF-8.•Highly thermally stable ZIF-8 crystals with uniform shapes and high surface areas.
This paper reports a facile method for the synthesis of zeolitic imidazolate framework-8 (ZIF-8) at room temperature in 10min. ZIF-8 crystals were produced from stoichiometric metal and ligand (1:2) concentrated aqueous solutions in the presence of ammonium hydroxide. The resulting ZIF-8 crystals possessed high surface area, large micropore volume, and had a truncated cubic morphology with an average particle size of ca. 0.7μm. TGA and XRD results revealed the structural stability of the as-synthesized ZIF-8 up to 250°C. The addition of an appropriate amount of ammonium hydroxide was proved to be essential for the formation of ZIF-8 crystal through deprotonation and coordination reaction. Furthermore, ZIF-8 crystals were successfully prepared from different zinc sources, and this method is promising for large-scale synthesis of ZIFs.
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•A self-crosslinking strategy to combine UiO-66 and nanocellulose is proposed.•A hierarchically structured MOF/cellulose aerogel was synthesized.•The micropores and accessibility of ...UiO-66 were well-preserved.•The UiO-66 loadings could reach up to 50 wt%.•The strategy opens a door for processing MOFs into a flexible form.
Composite UiO-66/nanocellulose aerogels with hierarchical pores and low density were prepared through a self-crosslinking method. The nanocellulose acted as the structural skeleton supporting and dispersing the UiO-66 particles. The micropore and accessibility of UiO-66 were well-preserved, making the composite aerogels ideal sorbents for water purification. The composite aerogels demonstrated high adsorption ability towards both anionic methyl orange (71.7 mg g−1) and cationic methylene blue (51.8 mg g−1). This work holds a promise to rational design and fabrication of MOF monoliths through group linkage.
Caudal-related homeobox transcription factor 2 (CDX2), an intestine-specific nuclear transcription factor, has been strongly implicated in the tumourigenesis of various human cancers. However, the ...functional role of CDX2 in the development and progression of colorectal cancer (CRC) is not well known. In this study, CDX2 knockdown in colon cancer cells promoted cell proliferation in vitro, accelerated tumor formation in vivo, and induced a cell cycle transition from G0/G1 to S phase, whereas CDX2 overexpression inhibited cell proliferation. TOP/FOP-Flash reporter assay showed that CDX2 knockdown or CDX2 overexpression significantly increased or decreased Wnt signaling activity. Western blot assay showed that downstream targets of Wnt signaling, including β-catenin, cyclin D1 and c-myc, were up-regulated or down-regulated in CDX2-knockdown or CDX2-overexpressing colon cancer cells. In addition, suppression of Wnt signaling by XAV-939 led to a marked suppression of the cell proliferation enhanced by CDX2 knockdown, whereas activation of this signaling by CHIR-99021 significantly enhanced the cell proliferation inhibited by CDX2 overexpression. Dual-luciferase reporter and quantitative chromatin immunoprecipitation (qChIP) assays further confirmed that CDX2 transcriptionally activates glycogen synthase kinase-3β (GSK-3β) and axis inhibition protein 2 (Axin2) expression by directly binding to the promoter of GSK-3β and the upstream enhancer of Axin2. In conclusion, these results indicated that CDX2 inhibits the proliferation and tumor formation of colon cancer cells by suppressing Wnt/β-catenin signaling.
A composite graphene oxide (GO)/nanocellulose aerogel was prepared by dispersing cellulose nanofibrils (CNFs) into GO nanosheets. CNFs with high aspect ratios and negative potential helped the ...exfoliation of GO flakes without the need of a chemical linker via steric hindrance and electrostatic repulsion. Water purification tests were performed using methylene blue (MB) and tetracycline (TC) as model pollutants. The composite aerogel obeyed a pseudo-second-order model and Langmuir adsorption isotherm. The composite aerogel possesses a maximum adsorption capacity of 111.2 mg/g for MB and 47.3 mg/g for TC. Meanwhile, the aerogel can be easily recycled and regenerated using ethanol. After three cycles, the aerogel can maintain a high removal efficiency for MB (98%) and TC (97%). The adsorption mechanism was mainly ascribed to electrostatic attraction and π-π interactions.
•Cellulose fibers promote the dispersion and exfoliation of GO flakes.•A composite GO/nanocellulose aerogel has been fabricated.•The aerogels exhibit high adsorption for methylene blue and tetracycline.•The adsorption mechanism is due to electrostatic attraction and π-π interactions.•The aerogels have good reusability and recyclability.
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