Effects of Galvanic Interaction between Chalcopyrite and Monoclinic Pyrrhotite on Their Flotation Separation

The galvanic interaction between chalcopyrite and monoclinic pyrrhotite and its effect on flotation separation were studied using monomineral flotation tests, adsorption capacity tests, X-ray photoelectron spectroscopy (XPS) characterization, and scanning electron microscopy (SEM) test. These results showed that the interaction promoted the reduction of O2 on the cathodic chalcopyrite surface and accelerated the generation of Fe(OH)3, which was not conducive to collector adsorption; hence, the flotation recovery decreased by 10–16%. On the other hand, galvanic interaction accelerated the oxidation of S on the anodic monoclinic pyrrhotite surface to S0 or SO42− and produced a large amount of H+, thus preventing the formation of Fe(OH)3. Meanwhile, the Cu2+ eluted from chalcopyrite surface activated monoclinic pyrrhotite; hence, the flotation recovery increased by 3–10%. Galvanic interaction reduced the floatability difference between the two minerals, and the separation difficulty was significantly increased. Even with an increase in the amount of lime, the separation could not be improved.

Paeonol Disrupts the Integrity of Aspergillus flavus Cell Walls via Releasing Surface Proteins, Inhibiting the Biosynthesis of β-1,3-Glucan and Promoting the Degradation of Chitin, and an Identification of Cell Surface Proteins

Paeonol can effectively inhibit Aspergillus flavus (A. flavus) via damaging cell walls. In this work, paeonol treatment remarkably destroyed both the outer amorphous layer and the inner fibrous layer of cell walls. Furthermore, FT-IR and XPS characterization showed that OH functional groups were altered and proteins in the outer layer were released. According to proteomic analysis, 605 proteins have been identified and annotated. The activities of β-1,3-glucan synthase and chitinase were prohibited and promoted, respectively, by paeonol treatment, however, the activities of β-1,3-glucanase and chitin synthase were not influenced. QRT-PCR results suggested that FKSP, CHIIII, and CHIV genes might be the antifungal targets of paeonol. In addition, paeonol can effectively restrain the pathogenicity of A. flavus on peanut butter. This study provided a new elucidation on the mode of action of paeonol against cell walls of A. flavus, facilitating the application of paeonol in the preservation of agricultural products.

Thermally Resilient Planar Waveguides in Novel nc-YSZ Transparent Ceramic by fs Laser Pulses

We report on thermally resilient planar waveguides fabricated on nc-YSZ by direct fs-laser inscription in transparent nc-yttria stabilized zirconia (nc-YSZ) polycrystalline ceramic. The waveguides consisted of rectangular sections (4.5 × 2 mm2) on the surface of the sample. Optical characterization at 633 and 810 nm was performed. We estimate a laser-induced refractive index contrast of 10–4. Post-waveguide-fabrication thermal annealing treatments at 750°C for 24 h were carried out to test the resilience of the waveguides and to further reduce the waveguide losses. Both micro-Raman spectroscopy and XPS characterization revealed unmodified lattice and steady chemical features, which are consistent with the waveguide thermal resilience. Our results suggest a promising potential use of nc-YSZ in harsh and high temperature demanding photonic environments.

Preparation and Application of Fluorine-Free Finishing Agent with Excellent Water Repellency for Cotton Fabric

Water repellent is an important functional finish for cotton fabric. However, cotton fabrics often have poor washing resistance and other performances after actual finishing. In this study, based on the structural characteristics of cotton fiber and durability of water repellent, a cross-linked amino long-chain alkyl polysiloxane (CAHPS) was first prepared, and then reacted with modified silica. Finally, a chemically bonded organic–inorganic nanohybrid cross-linked polysiloxane (rSiO2-CAHPS) was fabricated. Furthermore, the rSiO2-CAHPS was emulsified to obtain a durable fluorine-free water repellent. The water repellent finishing for cotton fabric was carried out by the pad–dry–cure process. After finishing, the cotton fabric had good resistance to conventional liquids and excellent washing resistance, and still maintained good water repellency after 30 rounds of soaping. Moreover, properties including air permeability, mechanical property and whiteness are hardly affected after finishing. SEM and XPS characterization show that a layer of dense silicon film is formed on the surface of cotton fabric by rSiO2-CAHPS water repellent. The existence of nanosilica can improve the surface roughness of cotton fibers. The synergistic effect of fiber matrix, nanoparticles and CAHPS endows the fabric with a micro/nano-multi-scale micro-rough structure, which improves the water repellency of cotton fabric after water repellent finishing.

Production of Activated Carbon Electrode for Energy Storage Application in Supercapacitors via KOH Activation of Waste Termite Biomass

The devastating effects of termites on wood and the contribution of termite activities to the rising levels of atmospheric CO2 and CH4 constitute a serious threat to global economy and the ozone layer. In order to stall the contribution of termites to the rising levels of greenhouse gases, this work considers the conversion of termite biomass to activated carbon electrode. The waste termite biomass obtained during the production of termite biodiesel was converted to activated carbon electrode by a one-step carbonization-activation process, using potassium hydroxide as activating agent. The optimal specific surface area of the activated carbon was recorded at 900 oC, 9 h and 3:1 KOH-biomass ratio. The surface morphology and functionalization of the activated carbon were examined using the SEM, TEM, XRD, Raman and XPS characterization techniques. The electrochemical performance of the activated carbon electrode was tested in aqueous (1 M H2SO4) and ionic liquid (1 M EMImBF4) electrolytes. Results obtained from cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance experiments showed that the specific capacitance of the activated carbon electrode was higher in 1 M H2SO4 (78 Fg-1 at 0.5 Ag-1) than in 1 M EMImBF4 (53 Fg-1 at 0.5 Ag-1). However, after completing 10, 000 chare-discharge cycles at 10 Ag-1, the activated carbon electrode lost ~ 5% of its specific capacitance in 1 M H2SO4 and ~ 2% of its capacitance in 1 M EMImBF4. Overall, the results showed that waste termite biomass could be valorised in the production of activated carbon for energy storage in supercapacitors.

The Optimization Parameters of Activated Biochar Derived From Pine Pyrolysis: Application in Methylene Blue Adsorption

To understand the interaction mechanism between adsorbent and adsorbate, activated biochar, prepared from pine sawdust using CO2 and H2O as activator, was employed to adsorb methylene blue in printing and dyeing pollutants. The pore structure, carbon structure of the aromatic ring system, and functional groups were investigated though SEM, nitrogen adsorption/desorption device (BET), Raman, and XPS characterization, and the adsorption kinetics and possible adsorption mechanism were also studied. The results showed that the activated biochar prepared by CO2 activation had more specific surface area, pore structure, and surface oxygen-containing functional groups than that prepared by H2O, which was more conductive to improving its adsorption capacity. The electrostatic interaction between the surface oxygen-containing functional groups in the adsorbents and the π-π interaction formed in the aromatic rings enhanced the adsorption capacity of activated biochar to methylene blue. The adsorption process of methylene blue by activated biochar was spontaneous, and it conformed to the pseudo-second-order kinetic characteristics and Langmuir adsorption isotherm equation. It was a monolayer adsorption and the maximum adsorption capacity was about 160 mg/g. Activated biochar as an adsorbent for wastewater treatment has promising application and development prospects.

Piezoelectric Response in WO3-x Thin Films by Aluminum Clustering

We report piezoelectric response of d33 = 35 ± 5 pm V− 1 on aluminum doped tungsten trioxide thin films (Al-WO3 − x), prepared by RF-sputtering and post annealing treatment in air atmosphere. Using XPS characterization indicate a stoichiometry of WO2.7 and Raman a distorted octahedral tungsten vibration mode of monoclinic WO3 at 236.9 cm− 1, 691 cm− 1 and 803 cm− 1 corresponding to O-W-O chemical bonds. The grazing incidence X-ray diffraction revealed a non-centrosymmetric monoclinic (P21/c) and tetragonal (P4/nmm) mixed phases of WO3 − x with islands of piezoelectric domains as observed by atomic force microscope, additionally atom probe tomography revealed diffusion of aluminum ions from Al2O3 substrate.

Quercetin as an Auxiliary Endodontic Irrigant for Root Canal Treatment: Anti-Biofilm and Dentin Collagen-Stabilizing Effects In Vitro

Bacterial reinfection and root fracture are the main culprits related to root canal treatment failure. This study aimed to assess the utility of quercetin solution as an adjunctive endodontic irrigant that does not weaken root canal dentin with commitment anti-biofilm activity and bio-safety. Based on a noninvasive dentin infection model, dentin tubules infected with Enterococcus faecalis (E. faecalis) were irrigated with sterile water (control group), and 0, 1, 2, 4 wt% quercetin-containing ethanol solutions. Live and dead bacteria percentages in E. faecalis biofilms were analyzed by confocal laser scanning microscopy (CLSM). Elastic modulus, hydroxyproline release and X-ray photoelectron spectroscopy (XPS) characterization were tested to evaluate the irrigants’ collagen-stabilizing effect. The cytotoxicity was tested by CCK-8 assay. Quercetin increased the proportion of dead bacteria volumes within E. faecalis and improved the flexural strength of dentin compared to control group (p < 0.05). Quercetin-treated dentin matrix had less elasticity loss and hydroxyproline release after collagenase degradation (p < 0.05). Moreover, quercetin solutions revealed an increase in the C-O peak area under both C1s and O1s narrow-scan spectra of XPS characterization, and no cytotoxicity (p > 0.05). Quercetin exhibited anti-biofilm activity, a collagen-stabilizing effect with cytocompatibility, supporting quercetin as a potential candidate for endodontic irrigant.