Graphene oxide intercalated Alk-MXene adsorbents for efficient removal of Malachite green and Congo red from aqueous solutions.

Currently, adsorbents with high adsorption performance for eliminating pollutants from discharged wastewater have received many researchers' attention. To this aim, a novel AMXGO absorbent was fabricated by intercalating graphene oxide (GO) into alkalized MXene (Alk-MXene) layer which exhibited high efficacy for the removal of cationic Malachite Green (MG) and anionic Congo Red (CR). Analysis of FTIR, XRD, SEM and TG presented that AMXGO absorbent have a typical three-dimensional layer by layer structure and abundant oxygen-containing groups and its thermal stability was remarkably improved. BET results elucidated that AMXGO1 adsorbent has larger specific surface area and pore volume (16.686 m2 g-1, 0.04733 cm3 g-1) as compared to Alk-MXene (4.729 m2 g-1, 0.02522 cm3 g-1). A dependence of adsorption performance on mass ratio between Alk-MXene and GO, initial dye concentration, contact time, temperature and pH was revealed. Maximum adsorption capacity of MG (1111.6 mg/g) and CR (1133.7 mg/g) were particularly found for AMXGO1 absorbent with a mass ratio of 3:1 and its removal for both dyes were higher than 92%. The adsorption process of AMXGO1 adsorbent for both MG and CR complies with pseudo-second-order kinetic model and Freundlich isotherm model. In addition, adsorption mechanism was explored that synergism effects as electrostatic attraction, π-π conjugates, intercalation adsorption and pore filling were the main driving force for the high adsorption performance of dye. Therefore, AMXGO adsorbent has a potential application prospect in the purification of dye wastewater.

The Extract of Pinellia Ternata-Induced Apoptosis of Leukemia Cells by Regulating the Expression of Bax, Bcl-2 and Caspase-3 Protein Expression in Mice.

The study aims to lessen the monetary burden on patients and society by decreasing the price of proprietary drugs used in leukemia therapy. Flow cytometry, reverse transcription polymerase chain reaction, western blot, and a patient-derived xenograft mouse model were used to confirm the therapeutic effect of Pinellia ternata extract on leukemia. Three types of leukemia cells (K562, HL-60, and C8166 cell lines) were found to undergo early apoptosis (P ≤ .05) after being exposed to P. ternata extract, as measured by flow cytometry. Reverse transcription polymerase chain reaction results showed that P. ternata extract at both middle (300 µg/mL) and high (500 µg/mL) concentrations was able to down-regulate Bcl-2 and upregulate mRNA expression of Bax and caspase-3. In the patient-derived xenograft mouse model formed by BALB/c-nu/nu nude mice, immunohistochemistry indicated that P. ternata extract effectively suppressed the proliferation of leukemia cells. Therefore, P. ternata extract at 300 µg/mL and 500 µg/mL could effectively inhibit myeloid and lymphocytic leukemia cell proliferation and promote leukemia cell apoptosis by regulating Bax/Bcl-2 and caspase-3.

Acrylic acid functionalized graphene oxide: High-efficient removal of cationic dyes from wastewater and exploration on adsorption mechanism.

A novel p(AA)-g-GO material was prepared by grafting polymerization of acrylic acid (AA) onto graphene oxide (GO) skeleton, presenting efficient removal of dyes from wastewater, because the layer spacing of GO is expanded and successfully introduced numerous polar carboxyl groups. The study revealed a rapid adsorption kinetic process and the adsorption capacity for methylene blue (MB) increases with pH, contact time, initial dye concentration and temperature. The maximum adsorption capacity is about 1448.2 mg/g at 25 °C for MB according to the Langmuir isotherm. More importantly, the adsorbent maintains excellent adsorption capacity after five cycles of adsorption-desorption and has remarkable selective separability for methylene blue/methyl orange mixed solution at pH = 10. Furthermore, the equilibrium adsorption capacities for other cationic dyes as malachite green (MG), basic fuchsin (BF) and rhodamine B (RhB) reached 582.1, 571.7 and 437.1 mg/g, respectively. Additionally, the mechanism analysis indicated that electrostatic interactions, π-π conjugation and hydrogen bonding are the predominant forces for adsorbing cationic dyes. Therefore, p(AA)-g-GO is an outstanding adsorbent and has a potential application prospect in the treatment of dye wastewater.

Mechanism of surface treatments on carbon nanotube transparent conductive films by three different reagents.

Transparent conductive films (TCFs) were fabricated via a spray-coating method with a solution prepared by dispersing single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecylbenzene sulfonate (SDBS) as surfactant. We explored the mechanism of HNO3 treatment by treating TCFs with different reagents. After being treated with different concentrations of reagents by HNO3, HCl, and NaNO3 to lower the sheet resistance of TCFs, the properties of TCFs were further characterized by a UV-VIS spectrophotometer, a four-point probe method, atom force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. In this study, we conclude that the HNO3 treatment results in a decrease in the sheet resistance of the TCFs due to the combined effect of acidity and oxidizability. The strong interaction of the strong acidity and strong oxidizing property of HNO3 causes the SDBS to be removed. To further improve the film conductivity of the TCFs, the experimental conditions of the HNO3 treatment were optimized.

Hierarchical chrysanthemum-flower-like carbon nanomaterials grown by chemical vapor deposition.

Novel hierarchical chrysanthemum-flower-like carbon nanomaterials (CFL-CNMs) were synthesized by thermal chemical vapor deposition based on acetylene decomposition. A scanning electron microscope and a transmission electron microscope were employed to observe the morphology and structure of the unconventional nanostructures. It is found that the CFL-CNMs look like a blooming chrysanthemum with a stem rather than a spherical flower. The carbon flower has an average diameter of 5 µm, an average stem diameter of 150 nm, branch diameters ranging from 20 to 70 nm, and branch lengths ranging from 0.5 to 3 µm. The morphologies of the CFL-CNMs are unlike any of those previously reported. Fishbone-like carbon nanofibers with a spindle-shaped catalyst locating at the tip can also be found. Furthermore, the catalyst split was proposed to elucidate the formation mechanism of CFL-CNMs. A large and glomerate catalyst particle at the tip of the carbon nanofiber splits into smaller catalyst particles which are catalytic-active points for branch formation, resulting in the formation of CFL-CNMs.

Evaporation dynamics of microdroplets on self-assembled monolayers of dialkyl disulfides.

We present a study of the static wettability and evaporation dynamics of sessile microdroplets of water on self-assembled monolayers (SAMs) prepared with unsymmetric dialkyl disulfides CH(3)-(CH(2))(11+m)-S-S-(CH(2))(11)-OH (m = 0, +/- 2, +/- 4, +/- 6) on gold-covered mica. The advancing and receding contact angles decrease linearly with increasing hydrophilicity of the SAM. The latter was changed either via the molar ratio or via the chain length of the hydroxyl-terminated alkyl chains in the monolayer. In contrast to SAMs made of thiols, the contact angle hysteresis was 10 degrees for all disulfides, irrespective of their chain lengths. During evaporation of single droplets, a transition from pinning to constant contact angle mode was observed. The transition time between the modes increases with the surface hydrophilicity, leading to longer pinning. This way, the time for complete droplet evaporation decreases by approximately 30% owing to the fact that during pinning the overall droplet area stays large for a longer time. For single droplets the measured total evaporation times agree well with the calculated ones, showing the validity of the standard evaporation model for both evaporation modes. In contrast to the results for single droplets, many droplets with different initial volumes show a power-law dependence on the total evaporation time with an exponent different from 1.5 as expected from the standard model. For disulfides with m not equal 0, the exponent is in the range of 1.40-1.47 increasing with the surface hydrophilicity. For the SAMs with m = 0 the exponent increases up to 1.61 for the most hydrophilic surface. We explain this deviation from the standard evaporation model with the presence of a liquid precursor film around the droplet, which either enhances or decelerates evaporation. Our results suggest that SAMs of dialkyl disulfides offer the possibility to tune the wettability of gold surfaces in a more controlled way than thiols do.

Microstructures formation by deposition of toluene drops on polystyrene surface.

Here we develop a new approach for producing diverse microstructures by deposition of nano-litre solvent droplets onto polymer surface, which is based on a syringe system coupling with an adjustable substrate stage. Two basic procedures, contact mode and non-contact mode, are used for providing either the sessile drop or the pendent drop. In the contact mode, the influences of process parameters and intrinsic parameters are extensively investigated. By varying the process parameters such as the substrate-approaching and retraction speeds and the delay between these two movements, the microstructures can be tuned from concave to convex, whereas by varying intrinsic parameters such as the initial drop volume,V-shaped and U-shaped concave structures can typically be generated. The drying of these microstructures can partially remove entrapped solvent from the swollen polymer material, and the removed solvent volume is found to correspond to the width of microstructures. However, the shapes of these microstructures show no changes before and after drying. Ripples perpendicular to the stretch direction appear in the center of the microstructures for the stretched polymer substrate and become much more regular with increasing stretch ratio. As a sessile solvent drop is replaced by a pendent solvent drop, a non-contact mode results. Without direct contact between the solvent and the polymer substrate, solvent vapor diffuses from the droplet surface into the polymer matrix and eventually provides concave structures. The shape of the concave structures is dependent on the exposure time of the solvent vapor.

Microstructures by solvent drop evaporation on polymer surfaces: dependence on molar mass.

When a solvent drop evaporates from a polymer surface, it leaves behind a characteristic structure, typically a crater. We deposited toluene drops with a microsyringe onto planar polystyrene (PS) surfaces and analyzed the surface topography after drying. For low molar mass PS (Mw = 20.9-24.3 kDa) dotlike protrusions with a ridge at the periphery formed on the polymer surface. With increasing molar mass the central region decreased in height. At Mw = 29.6-643 kDa a craterlike structure with a depression in the center and a ridge was observed. At even higher molar mass, irregular structures without rotational symmetry occurred. We explain the observed dependence on the molar mass with a different degree of entanglement, leading to different dissolution rates and different diffusion constants.