Property of Modified Bovine Bone Glue as an Environmental Additive in Water-Based Drilling Fluids.

At present, animal bone glue (BG) is being widely used in many fields, but there are no studies reported on oilfield chemistry. In this paper, an environmental water-based drilling fluids additive named bromoethane-modified bone glue (BG) was developed by using bovine bone glue and bromoethane as raw materials, anhydrous ethanol as solvent, sodium hydroxide as alkaline hydrolysis agent, and sodium carbonate as a system pH regulator. The inhibition, filtration performance, and temperature resistance of BG were evaluated. Performance study results show that the linear swelling rate of sodium bentonite (Na-MMT) was decreased from 50.2% (in tap water) to 38.2% (in 4 wt % BG solutions), and filtration loss was reduced from 30 mL (in tap water) to 12 mL (in 5 wt % BG). Hot-rolling experiments show that the BG solution still exhibits good performance even after 16 h × 130 °C. The reasons for BG to achieve excellent performance were analyzed through scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ζ potential, thermogravimetric analysis (TGA), and microstructure. The results of SEM and FT-IR show that BG can fully dissolve in water and adsorb on the surface of clay particles by relying on its own adsorption functional groups such as -OH and -COOH. When 4% BG was added, ζ potential analysis revealed that the clay particle size declined by 0.502 µm, which indicated that BG can inhibit clay hydration swelling dispersion.

Three-Dimensional Visualization of Oxygen-Vacancy Migration and Redistribution in Ca-Substituted BiFeO3.

Ionic movement has received renewed attention in recent years, particularly in the field of ferroelectric oxides, since it is intrinsically linked to chemical reaction kinetics and ferroelectric phase stability. The associated surface electrochemical processes coupled local ionic transport with an applied electric bias, exhibiting very high ionic mobility at room temperature based on a simple electrostatics scenario. However, few studies have focused on the applied-polarity dependence of ionic migration with directly visualized maps. Here, we use incorporated experiments of conductive scanning probe microscopy and time-of-flight secondary ion mass spectrometry to investigate oxygen ionic migration and cation redistribution in ionic oxides. The local concentrations of oxygen vacancies and other cation species are visualized by three-dimensional mappings, indicating that oxygen vacancies tend to be ejected toward the surface. An accumulation of oxygen vacancies and ionic redistribution strongly depend on tip polarity, thus corroborating their role in the electrochemical process. This work illustrates the interplay between ionic kinetics and electric switching.

Charge disproportionation-induced multiferroics and electric field control of magnetism in a 2D MXene - Mo2NCl2.

Two-dimensional (2D) magnetoelectric multiferroic materials with the coexistence of magnetization and ferroelectric polarization hold potential for application for the development of next-generation nano-memory devices. However, intrinsic 2D multiferroics with a high critical temperature and strong magnetoelectric coupling are still rare to date. Here, we propose a novel mechanism of 2D monolayer multiferroicity. Based on density functional theory (DFT), we predicted that in a Mo2NCl2 monolayer, the non-equilibrium charge disproportionation of Mo ions will induce an out-of-plane electric polarization, making this material a 2D monolayer multiferroic material. More importantly, the magnetic critical temperature is calculated to be ∼168 K, which is larger than those of the recently reported 2D multiferroic and ferromagnetic systems. Our findings also provide a promising platform to control the magnetic properties and electric behavior in 2D multiferroics using an external electric field.

Plant growth strategy determines the magnitude and direction of drought-induced changes in root exudates in subtropical forests.

Root exudates are an important pathway for plant-microbial interactions and are highly sensitive to climate change. However, how extreme drought affects root exudates and the main components, as well as species-specific differences in response magnitude and direction, are poorly understood. In this study, root exudation rates of total carbon (C) and its components (e.g., sugar, organic acid, and amino acid) were measured under the control and extreme drought treatments (i.e., 70% throughfall reduction) by in situ collection of four tree species with different growth rates in a subtropical forest. We also quantified soil properties, root morphological traits, and mycorrhizal infection rates to examine the driving factors underlying variations in root exudation. Our results showed that extreme drought significantly decreased root exudation rates of total C, sugar, and amino acid by 17.8%, 30.8%, and 35.0%, respectively, but increased root exudation rate of organic acid by 38.6%, which were largely associated with drought-induced changes in tree growth rates, root morphological traits, and mycorrhizal infection rates. Specifically, trees with relatively high growth rates were more responsive to drought for root exudation rates compared with those with relatively low growth rates, which were closely related to root morphological traits and mycorrhizal infection rates. These findings highlight the importance of plant growth strategy in mediating drought-induced changes in root exudation rates. The coordinations among root exudation rates, root morphological traits, and mycorrhizal symbioses in response to drought could be incorporated into land surface models to improve the prediction of climate change impacts on rhizosphere C dynamics in forest ecosystems.

Origin of the Ultrafast Response of the Lateral Photovoltaic Effect in Amorphous MoS2/Si Junctions.

The lateral photovoltaic (LPV) effect has attracted much attention for a long time because of its application in position-sensitive detectors (PSD). Here, we report the ultrafast response of the LPV in amorphous MoS2/Si (a-MoS2/Si) junctions prepared by the pulsed laser deposition (PLD) technique. Different orientations of the built-in field and the breakover voltages are observed for a-MoS2 films deposited on p- and n-type Si wafers, resulting in the induction of positive and negative voltages in the a-MoS2/n-Si and a-MoS2/p-Si junctions upon laser illumination, respectively. The dependence of the LPV on the position of the illumination shows very high sensitivity (183 mV mm-1) and good linearity. The optical relaxation time of LPV with a positive voltage was about 5.8 µs in a-MoS2/n-Si junction, whereas the optical relaxation time of LPV with a negative voltage was about 2.1 µs in a-MoS2/p-Si junction. Our results clearly suggested that the inversion layer at the a-MoS2/Si interface made a good contribution to the ultrafast response of the LPV in a-MoS2/Si junctions. The large positional sensitivity and ultrafast relaxation of LPV may promise the a-MoS2/Si junction's applications in fast position-sensitive detectors.

Near-ultraviolet lateral photovoltaic effect in Fe3O4/3C-SiC Schottky junctions.

In this paper, we report a sensitive lateral photovoltaic effect (LPE) in Fe3O4/3C-SiC Schottky junctions with a fast relaxation time at near-ultraviolet wavelengths. The rectifying behavior suggests that the large build-in electric field was formed in the Schottky junctions. This device has excellent position sensitivity as high as 67.8 mV mm-1 illuminated by a 405 nm laser. The optical relaxation time of the LPE is about 30 µs. The fast relaxation and high positional sensitivity of the LPE make the Fe3O4/3C-SiC junction a promising candidate for a wide range of ultraviolet/near-ultraviolet optoelectronic applications.

Origin of colossal dielectric permittivity of rutile Ti0.9In0.05Nb0.05O2: single crystal and polycrystalline.

In this paper, we investigated the dielectric properties of (In + Nb) co-doped rutile TiO2 single crystal and polycrystalline ceramics. Both of them showed colossal, up to 10(4), dielectric permittivity at room temperature. The single crystal sample showed one dielectric relaxation process with a large dielectric loss. The voltage-dependence of dielectric permittivity and the impedance spectrum suggest that the high dielectric permittivity of single crystal originated from the surface barrier layer capacitor (SBLC). The impedance spectroscopy at different temperature confirmed that the (In + Nb) co-doped rutile TiO2 polycrystalline ceramic had semiconductor grains and insulating grain boundaries, and that the activation energies were calculated to be 0.052 eV and 0.35 eV for grain and grain boundary, respectively. The dielectric behavior and impedance spectrum of the polycrystalline ceramic sample indicated that the internal barrier layer capacitor (IBLC) mode made a major contribution to the high ceramic dielectric permittivity, instead of the electron-pinned defect-dipoles.