With the increasing requirements of reliable and environmentally friendly energy resources, porous materials for sustainable energy conversion technologies have attracted intensive interest in the past decades. As an important block of porous materials, biomimetic smart nanochannels (BSN) have been developed rapidly into an attractive field for their well-tunable geometry and chemistry. With inspiration from nature, many works have been reported to utilize BSN to harvest clean energy. In this review, we summarize recent progress in the BSN for power harvesting from four parts of brief introduction of BSN, biological prototypes for power harvesting, BSN-based energy conversion, and conclusion and outlook. Overall, by learning from nature, exploiting new avenues and improving the performance of BSN, a number of exciting developments in the near future may be anticipated.
This paper proposed two robust scheduling formulations in real manufacturing systems based on the concept of bad scenario set to hedge against processing time uncertainty, which is described by discrete scenarios. Two proposed robust scheduling formulations are applied to an uncertain job-shop scheduling problem with the makespan as the performance criterion. The united-scenario neighbourhood (UN) structure is constructed based on bad scenario set for the scenario job-shop scheduling problem. A tabu search (TS) algorithm with the UN structure is developed to solve the proposed robust scheduling problem. An extensive experiment was conducted. The computational results show that the first robust scheduling formulation could be preferred to the second one for the discussed problem. It is also verified that the obtained robust solutions could hedge against the processing time uncertainty through decreasing the number of bad scenarios and the degree of performance degradation on bad scenarios. Moreover, the computational results demonstrate that the developed TS algorithm is competitive for the proposed robust scheduling formulations. 相似文献
There is a growing need in developing a reliable and eco-friendly methodology for the synthesis of metallic nanoparticles, which may be applied for many nanotechnological applications. Natural compounds such as biopolymers are one of the resources which could be used for this purpose. The present study involves the development of a simple, ecological and user-friendly method in synthesizing silver nanoparticles by using carboxymethylated-curdlan or fucoidan as reducing and stabilizing agents. Reduction of silver ions by these biopolymers occurred when heating at 100 °C, led to the formation of silver nanoparticles in the range of 40–80 nm in dimensions. The silver nanoparticles were formed readily within 10–15 min. Morphological observation and characterization of the silver nanoparticles were performed by using dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and UV–vis absorption spectrophotometer. The size of silver nanoparticles can be controlled by using different concentrations of carboxymethylated-curdlan, fucoidan or silver nitrate. This way of silver nanoparticles preparation is easy, fast, user-friendly and suitable for large-scale production. 相似文献
Silk is a widely available, edible, biocompatible, and environmentally sustainable natural material. Particulate matter (PM) pollution has drawn considerable attention because it is a serious threat to public health. Herein, we report a human-friendly silk nanofiber air filter, which exhibits superior filtration efficiency for both PM2.5 and submicron particles with obviously low pressure drop and low basis weight compared to typical commercial microfiber air filters. Additionally, other functions such as antibacterial activity could be easily integrated into the silk nanofiber air filters, enabling the fabrication of multifunctional air filters. All the above characteristics, combined with the natural abundance and biocompatibility of silk, suggest a great potential for the use of silk nanofibers as air filters, especially as comfortable and personal air purifiers.
Acoustic emission (AE) technique is a widely used CM technique. In this paper, AE technique was used to characterize the fatigue failure process for carbon fiber sheet (CFS) reinforced steel rod. The AE signals at the frequency band of 50–400 kHz are detected by using AE sensors mounted on the steel rod and analyzed by both parameter analysis and spectrum analysis in order to investigate the feasibility of using the AE technique to identify various failure modes during fatigue failure process for CFS reinforced steel rods. Tension-tension fatigue experiments were carried out on both CFS reinforced and unreinforced steel rods. Based on AE energy parameter analysis using wavelet decomposition method, failure process was initially divided into three stages for unreinforced specimen and seven stages for CFS reinforced specimen. The frequency contents within the frequency band of 50–400 kHz for various failure modes in each stage including crack initiation, developing, final rupture in steel rod and matrix crack, debonding in CFS were revealed by fast Fourier transform (FFT) method. Further wavelet transform (WT) analysis was performed to illustrate the sequences of the failure modes and main failure mode in each stage by the occurrence time and longest duration time, respectively. This work indicates that the proposed method is promising for distinguishing failure stages qualitatively and identifying failure modes quantitatively in CFS reinforced steel rods. 相似文献
2D transition metal dichalcogenides have attracted much attention in the field of spintronics due to their rich spin‐dependent properties. The promise of highly compact and low‐energy‐consumption spin‐orbit torque (SOT) devices motivates the search for structures and materials that can satisfy the requirements of giant perpendicular magnetic anisotropy (PMA) and large SOT simultaneously in SOT‐based magnetic memory. Here, it is demonstrated that PMA and SOT in a heavy metal/transition metal ferromagnet structure, Pt/[Co/Ni]2, can be greatly enhanced by introducing a molybdenum disulfide (MoS2) underlayer. According to first‐principles calculation and X‐ray absorption spectroscopy (XAS), the enhancement of the PMA is ascribed to the modification of the orbital hybridization at the interface of Pt/Co due to MoS2. The enhancement of SOT by the role played by MoS2 is explained, which is strongly supported by the identical behavior of SOT and PMA as a function of Pt thickness. This work provides new possibilities to integrate 2D materials into promising spintronics devices. 相似文献
To explore new constituents in two‐dimensional (2D) materials and to combine their best in van der Waals heterostructures is in great demand as being a unique platform to discover new physical phenomena and to design novel functionalities in interface‐based devices. Herein, PbI2 crystals as thin as a few layers are synthesized, particularly through a facile low‐temperature solution approach with crystals of large size, regular shape, different thicknesses, and high yields. As a prototypical demonstration of band engineering of PbI2‐based interfacial semiconductors, PbI2 crystals are assembled with several transition metal dichalcogenide monolayers. The photoluminescence of MoS2 is enhanced in MoS2/PbI2 stacks, while a dramatic photoluminescence quenching of WS2 and WSe2 is revealed in WS2/PbI2 and WSe2/PbI2 stacks. This is attributed to the effective heterojunction formation between PbI2 and these monolayers; type I band alignment in MoS2/PbI2 stacks, where fast‐transferred charge carriers accumulate in MoS2 with high emission efficiency, results in photoluminescence enhancement, and type II in WS2/PbI2 and WSe2/PbI2 stacks, with separated electrons and holes suitable for light harvesting, results in photoluminescence quenching. The results demonstrate that MoS2, WS2, and WSe2 monolayers with similar electronic structures show completely distinct light–matter interactions when interfacing with PbI2, providing unprecedented capabilities to engineer the device performance of 2D heterostructures. 相似文献
The single‐atom transistor represents a quantum electronic device at room temperature, allowing the switching of an electric current by the controlled and reversible relocation of one single atom within a metallic quantum point contact. So far, the device operates by applying a small voltage to a control electrode or “gate” within the aqueous electrolyte. Here, the operation of the atomic device in the quasi‐solid state is demonstrated. Gelation of pyrogenic silica transforms the electrolyte into the quasi‐solid state, exhibiting the cohesive properties of a solid and the diffusive properties of a liquid, preventing the leakage problem and avoiding the handling of a liquid system. The electrolyte is characterized by cyclic voltammetry, conductivity measurements, and rotation viscometry. Thus, a first demonstration of the single‐atom transistor operating in the quasi‐solid‐state is given. The silver single‐atom and atomic‐scale transistors in the quasi‐solid‐state allow bistable switching between zero and quantized conductance levels, which are integer multiples of the conductance quantum G0 = 2e2/h. Source–drain currents ranging from 1 to 8 µA are applied in these experiments. Any obvious influence of the gelation of the aqueous electrolyte on the electron transport within the quantum point contact is not observed. 相似文献