Search

Electrical anisotropy has a significant impact on the observation data of the magnetotelluric (MT) method; therefore, it is necessary to develop forward and inverse methods in electrical anisotropic media. Based on the axis anisotropic electric field control equations, forming a large linear equation through staggered finite difference approximation, adding boundary conditions, and using the quasi-minimum residual method to solve the equation, this study obtained MT forward modeling results in axis anisotropic media. The correctness of the algorithm was verified by comparing it with the 2D quasi-analytic solution. By designing several sets of axis anisotropic 3D models, the characteristics of the apparent resistivity tensor and tipper were analyzed. The results indicated that the py, p^y and Tzy are sensitive to changes in resistivity in the X direction of the anomalous body, whereas the pyx, paxx and Tzx are sensitive to changes in resistivity in the Y direction. The apparent resistivity tensor and tipper are insensitive to changes in resistivity in the Z direction of the anomalous body. For exploration of anisotropic media, the apparent resistivity tensor and tipper of MT can identify the changes in resistivity in two horizontal axes directions and the boundaries of the anomalous body, which has the advantages for exploration. [ABSTRACT FROM AUTHOR]

The exploration of unleaded free-cutting Cu40Zn brass with excellent mechanical and tribological properties has always drawn the attention of researchers. Due to its attractive properties combining metals and ceramics, Ti3AlC2 was added to Cu40Zn brass using high-energy milling and hot-pressing sintering. The effects of Ti3AlC2 on the microstructure, mechanical and tribological properties of Cu40Zn-Ti3AlC2 composites were studied. The results showed that Ti3AlC2 could suppress the formation of ZnO by adsorbing oxygen impurity and promote the formation of the β phase by releasing the β-forming element Al to the substrate. The hardness and wear resistance of Cu40Zn-Ti3AlC2 composites increased with increasing Ti3AlC2 content from 0 to 5 wt.%. The proper Ti3AlC2 additive was beneficial to both the strength and plasticity of the composites. The underlying mechanisms were discussed. [ABSTRACT FROM AUTHOR]

With the background of the fossil fuel energy crisis, the development of self-healing and recyclable polymer materials has become a research hotspot. In this work, a kind of cross-linking agent with pendent furan groups was first prepared and then used to produce the Polyurethane elastomer based on Diels–Alder chemistry (EPU–DA). In addition, in order to further enhance the mechanical properties of the elastomer, cellulose nanofibers (CNFs) were added into the Polyurethane system to prepare a series of composites with various contents of CNF (wt% = 0.1~0.7). Herein, the FTIR and DSC were used to confirm structure and thermal reversible character. The tensile test also indicated that the addition of CNF increased the mechanical properties compared to the pure Polyurethane elastomer. Due to their reversible DA covalent bonds, the elastomer and composites were recycled under high-temperature conditions, which extends Polyurethane elastomers' practical applications. Moreover, damaged coating can also be repaired, endowing this Polyurethane material with good potential for application in the field of metal protection. [ABSTRACT FROM AUTHOR]

This article presents a capacitor‐less low dropout (LDO) regulator with a high power supply rejection (PSR) for system‐on‐chip (SoC) applications. With the proposed adaptive bulk‐driven feedforward (ABDFF) technique, in which the ripples are injected adaptively to the bulk of power transistor, the LDO maintains a steady PSR enhancement in wide load conditions, and a lower quiescent current and faster load transient response are realized. Post‐layout simulation results show that the proposed LDO regulator achieves −75‐dB PSR at 1 MHz from 1 to 100 mA and 60‐fs figure of merit (FoM) with a 100‐pF load capacitor. [ABSTRACT FROM AUTHOR]

Magnetron-sputtered WS2 composite thin films are solid lubricants with excellent performances. However, the low hardness of the WS2 thin films necessitates the further improvement of their wear resistance. For this purpose, an effective strategy is to alternately deposit or code posit WS2 and a hard phase, such as TiB2, to form hard lubricant thin films. Herein, a TiB2 thin film was prepared under the same conditions as those used for depositing the WS2 thin film with a dense structure and excellent tribological properties. Because of the high deposition energy of high-power impulse magnetron sputtering (HiPIMS), the TiB2 thin film possesses a dense structure and leather-like flat surface (hardness = 24.17 GPa). The friction coefficient of the film under different loads ranges between 0.6 and 0.8. The wear rate of the thin film increases with load, mainly because of fatigue wear and abrasive wear. Under high loads, obvious furrow-like wear marks are observed. At different sliding frequencies, except 8 Hz, the friction coefficient of the film ranges from 0.6 to 0.8. The main wear mode is fatigue wear, particularly at increasing sliding frequencies. Although the film possesses a relatively high friction coefficient, its wear resistance is excellent (minimum wear rate = 1.96 × 10−6 mm3/(N·m)). [ABSTRACT FROM AUTHOR]

In this work, the Polyurethane/MoS2 composites (PUM) filled with different amount of modified molybdenum disulfide (MoS2) were prepared by solution-blending-casting method. The thermal reversible Diels–Alder (DA) bonds enabled the polymer system recyclable ability. The modified MoS2 were obtained by tannic acid (TA) assistant ultra-sonication exfoliation method were used to improve the gas barrier performance of materials. Compared with the pure PU, about twofold decrease in oxygen gas permeability of PUM composites (from 6719 to 3927 cm3/m2˙d˙Pa) were obtained with 1 wt% MoS2. More important, the samples showed excellent gas barrier and mechanical properties before and after being hygrothermal aged for 100 h. The PUM composites had good gas barrier and recyclability and had great potential application prospects in packing materials. [ABSTRACT FROM AUTHOR]

The permanently chemically cross‐linking solid–solid phase change materials (SSPCMs) were designed to solve the problem of leakage and poor shape stability during the whole process of phase transformation. However, these materials lead to environment pollution and resources waste because of the non‐recyclability. Therefore, a SSPCMs was fabricated using dynamic thermal reversible Diels–Alder bonds. The prepared SSPCMs exhibited excellent shape, heat storage stability, and reliability and reprocessed ability, resulting from dynamic Diels–Alder bonds. Moreover, the Halloysite nanotubes decorated with Fe3O4 nanoparticles (HNTs@Fe3O4) were used to enhance the thermal conductivity of SSPCMs. When the filler content was 0.5 wt%, the best integrated properties (phase change properties and thermal conductivity) of the SSPCMs were obtained, it had the highest melting and freezing phase change enthalpies about 116.8 and 127.2 J/g, and thermal conductivity value, 0.223 W/m K, which was 101% higher than pure SSPCMs. Hence, the prepared SSPCMs can be considered as promising save‐energy, friendly‐environment thermal management materials. [ABSTRACT FROM AUTHOR]

Although ovarian cancer is common, its prognosis remains poor because of drug resistance and early metastasis. Polysaccharides extracted from Bangia fuscopurpurea (BFP) are potential anti‐cancer agents, but the mechanisms underlying their effects in human ovarian cancer remain unclear. Here, we investigated the mechanisms of action of BFP polysaccharides in A2780 ovarian cancer cells using cell migration, invasion, apoptosis, and autophagy assays. Transwell assays indicated that BFP inhibited cell migration and invasion. Flow cytometry analysis showed that BFP treatment induced apoptosis and reactive oxygen species production, while significantly reducing mitochondrial membrane potential. Reverse transcription–polymerase chain reaction and Western blot analyses revealed changes in the expression of apoptosis‐ and autophagy‐related cellular mRNAs and proteins, respectively, following BFP treatment for 24 h. Transmission electron microscopy revealed that BFP induced autophagy in A2780 cells. These findings demonstrate that BFP may be useful for developing functional foods for cancer therapy. [ABSTRACT FROM AUTHOR]

Obtaining detailed information regarding the interfacial characteristics of metal/hexagonal-TMN composites is imperative for developing these materials with optimal mechanical properties. To this end, we systematically investigate the work of adhesion, fracture toughness, and interfacial stability of M/Cr2N and M/V2N interfaces using first-principles calculations. The orientation (0001) of hexagonal phases and (111) of fcc phases are selected as the interface orientations. Accordingly, we construct M/Cr2N interface models by considering 1N, 2N, and Cr terminations of Cr2N(0001), as well as two stacking sequences (top and hollow sites) for the 1N- and 2N-terminated interface models, respectively. The M/V2N interface models are constructed in the same way. The V-terminated Ni/V2N interface is demonstrated to provide a good combination of the work of adhesion, fracture toughness, and interfacial stability. Therefore, the Ni/V2N interface model can be regarded as the preferred configuration among the metal/hexagonal-TMN interface models considered. The present results offer a practical perspective for tailoring the interfaces in metal/hexagonal-TMN composite materials to obtain improved mechanical properties. [ABSTRACT FROM AUTHOR]