Gas sensors based on tin dioxide-carbon nanotube composite films were fabricated by a simple inexpensive sol-gel spin-coating method using PEG400 as a solvent. Nanostructured copper was coated on ...CNTs/SnO
2
film, and then copper was transformed into copper oxide at 250 °C. Resistivity of the final composite films is highly sensitive to the presence of H
2
S, which became easily attached or detached at room temperature. The response and recovery time of the sensor are 4 min and 10 min, and the value of sensitivity is 4.41, respectively. Meanwhile, the CNTs/SnO
2
/CuO sensor also has low detection limit, high selectivity toward H
2
S, and stable performance with different concentrations of H
2
S.
We report a highly efficient and reusable bifunctional nanostructured composite catalyst synthesized by a scalable facile hydrothermal method which enables the precise control of size and morphology ...of nanoparticles, wherein Au nanoparticles (NPs) and Fe3O4 particles exhibit excellent dispersing ability on the rGO (reduced graphene oxide) sheet surface (designated as rGO/Fe3O4/Au) to avoid adverse agglomeration between the nano particles and overlapping of the rGO sheets concurrently. The resultant bifunctional composite shows a high performance in the catalytic reduction of 4-nitrophenol (4-NP) with a conversion of 97% in 5 min and presents good reusability through highly efficient recovery by using external magnetic fields. In particular, there was no significant loss in catalytic activity of the reused catalysts even after being recycled for 8 cycles, displaying attractive potential in industrial applications where separation and recycling are imperative. The rational design provides an approach to synthesize a graphene-based composite with an interesting structure and multi-functional properties as well.
Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, especially if they can be easily processed and withstand harsh environments. ...Herein, layer-structured Fe–Si–B/Ni–Cu–P metallic glass composites have been developed by simple electroless plating Ni–Cu–P coating on commercial Fe–Si–B metallic glasses. The 0.1 mm-thick composite shows EMI shielding effectiveness of 40 dB over the X-band frequency range, which is higher than those of traditional metals, metal oxides, and their polymer composites of larger thickness. Most of the applied electromagnetic waves are proved to be absorbed rather than bounced back. This performance originates from the combination of a superior soft magnetic property, excellent electrical conductivity, and multiple internal reflections from multilayer composites. In addition, the flexible composites also exhibit good corrosion resistance, high thermal stability, and excellent tensile strength, making them suitable for EMI shielding in harsh chemical or thermal environments.
In order to solve the problem of performance degradation, such as local optimality, that may occur when shallow learning is used to predict the high-rise buildings seismic response under difficult ...conditions, a high-rise building vibration intelligent control method integrating genetic algorithms and long short-term memory networks is proposed. First, a structural response prediction model is constructed and combined with vibration control theory. Furthermore, an intelligent control algorithm using long short-term memory networks is designed. In conjunction with this algorithm, a centralized controller that integrates convolutional neural networks at different levels is designed. The structure of the centralized control system is improved, and genetic algorithms and Lyapunov stability theory are used to optimize thenetwork hyperparameters through deep learning. The results showed that this framework had high prediction accuracy, with the smallest relative difference in predicting C-library data at -0.0053 cm on average. The largest prediction error for B-library data was 0.015 cm on average. The long short-term memory network had the smallest prediction error and the best learning and prediction performance. When the degradation level of each layer stiffness in the benchmark model was between 10.2% and 20.5%, this intelligent controller achieved the best control effect, maintaining above 39.8%. Optimized using genetic algorithm, the optimal fitness value after 80 iterations represented controllerloss function value, which were 8.3×10-5, 2.3×10-4, 2.2×10-4, and 3.0×10-4, respectively, demonstrating good prediction results. Compared with traditional trial calculation methods, this algorithm has higher computational efficiency and accuracy. The fusion of genetic algorithms and long short-term memory networks with different structural forms shows good seismic reduction effects on the time responses of benchmark models. The research method has good prediction accuracy, high reliability, and flexible system design, providing new strategies for intelligent control of high-rise building structures under different conditions.
Fruit skin color is an important trait of the hawthorn tree, which has an important influence on fruit quality. Crataegus pinnatifida Bge. var. Major N.E.Br. Is one of the most widely cultivated ...varieties in China and has a long history of medicinal use. In recent years, it has attracted the attention of the world due to its nutritional and medicinal values. Skin color is the focus of breeders and food processors. At present, skin color-related genes have still not been mapped. In this study, “Shandong Da Mianqiu” (♀, red skin color), “Da Huang Mianzha” (♂, yellow skin color) and 131 F1 hybrids were used to construct genetic map of hawthorn by RAD-seq, and QTL mapping was performed by combining these features with the hue angle and the observed color. In this study, 13,260 SNP was assigned to 17 linkage groups, with an integrated map covering 2,297.75 cM was constructed. A total of 5 QTLs related to hawthorn skin color were detected on LG1, LG3 and LG15. Whether hue angle or pericarp color acts as phenotype for QTL mapping, the candidate genes include bHLH086 , WD repeat regions and Myb -like. bHLH , WD and Myb play an important role in the color regulation of Hawthorn skin color. These results lay a solid foundation for QTL mapping and molecular marker-assisted breeding of hawthorn.
In the current data age, the fundamental research related to optical applications has been rapidly developed. Countless new-born materials equipped with distinct optical properties have been widely ...explored, exhibiting tremendous values in practical applications. The optical data storage technique is one of the most significant topics of the optical applications, which is considered as the prominent solution for conquering the challenge of the explosive increase in mass data, to achieve the long-life, low-energy, and super high-capacity data storage. On this basis, our review outlines the representative reports for mainly introducing the functional systems based on the newly established materials applied in the optical storage field. According to the material categories, the representative functional systems are divided into rare-earth doped nanoparticles, graphene, and diarylethene. In terms of the difference of structural features and delicate properties among the three materials, the application in optical storage is comprehensively illustrated in the review. Meanwhile, the potential opportunities and critical challenges of optical storage are also discussed in detail.
Carbon aerogels are elastic, mechanically robust and fatigue resistant and are known for their promising applications in the fields of soft robotics, pressure sensors etc. However, these aerogels are ...generally fragile and/or easily deformable, which limits their applications. Here, we report a synthesis strategy for fabricating highly compressible and fatigue-resistant aerogels by assembling interconnected carbon tubes. The carbon tube aerogels demonstrate near-zero Poisson's ratio, exhibit a maximum strength over 20 MPa and a completely recoverable strain up to 99%. They show high fatigue resistance (less than 1.5% permanent degradation after 1000 cycles at 99% strain) and are thermally stable up to 2500 °C in an Ar atmosphere. Additionally, they possess tunable conductivity and electromagnetic shielding. The combined mechanical and multi-functional properties offer an attractive material for the use in harsh environments.
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•Realized the self-assembling of rosette-type 3D Ni-Al LDH nano material.•Presenting very high area-normalized capacity and excellent rate capability•Exhibiting a mechanical ...robustness and a capability of accommodating volume changes.
We report the synthesis of a rosette-type three-dimensional Ni-Al layered double hydroxide (Ni-Al LDH) positive electrode material for energy storage devices using a template-free, simple, self-assembling hydrothermal synthesis method. Poly (sodium-p-styrene-sulfonate) (PSS) plays a key role in efficiently controlling the morphology. Moreover a model that explains the formation mechanism of rosette-type Ni-Al LDH is proposed. The model is verified by a series of experiments. SEM images reveal that the three-dimensional (3D) structure of Ni-Al LDH consists of individual nanosheets that form a rosette-type morphology thus improving its mechanical stability. The electrochemical properties of the material were studied by means of cyclic voltammetry (CV), galvanostatic charge/discharge measurements, and by electrochemical impedance spectroscopy (EIS). Owing to the greatly improved faradaic redox reaction and mass transfer, the 3D Ni-Al LDH structure exhibits excellent energy storage performance. This positive electrode material shows a high specific capacity of 788C/g (the corresponding area-normalized capacity is 23.64C/cm2) at a charge/discharge current density of 1A/g and retains 82.9% of its capacity after 1000 cycles at current densities of 2A/g. These results illustrate that the rosette-type Ni-Al LDH is a highly promising active material for energy storage application. Using our methodology, it can be synthesized in a simple, controllable low cost way.
Wire and arc additive manufacturing (WAAM) is a competitive technique, which enables the fabrication of medium and large metallic components. However, due to the presence of coarse columnar grains in ...the additively manufactured parts, the resultant mechanical properties will be reduced, which limits the application of WAAM processes in the engineering fields. Grain refinement and improved mechanical properties can be achieved by introducing ultrasonic vibration. Herein, we applied ultrasonic vibration to the WAAM process and investigated the effects of wire feed speed, welding speed, and ultrasonic amplitude on the weld formation and grain size during ultrasonic vibration. Finally, a regression model between the average grain size and wire feed speed, welding speed, and ultrasonic amplitude was established. The results showed that due to the difference in heat input and cladding amount, wire feed speed, welding speed, and ultrasonic amplitude have a significant influence on the weld width and reinforcement. Excessive ultrasonic amplitude could cause the weld to crack during spreading. The average grain size increased with increasing wire feed speed and decreasing welding speed. With increasing ultrasonic amplitude, the average grain size exhibited a trend of decreasing first and then increasing. This would be helpful to manufacture parts of the required grain size in ultrasonic vibration-assisted WAAM fields.
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