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This paper aims to prepare third-order nonlinear optical (NLO) organic materials with large nonlinear optimization value, high damage threshold and ultrafast response time.

A series of novel symmetric and asymmetric compounds possessing third-order NLO properties were synthesized using 1,3,5-tribromobenzene as the basis. The photophysical and electrochemical properties, as well as the click reactions, were characterized by means of UV–VIS–NIR absorption spectroscopy and cyclic voltammetry.

The donor–acceptor chromophores were inserted into compound, making the molecule to have a broader absorption in the near-infrared regions and a narrower optical and electrochemical band gap. It also formed an electron-delocalized organic system, which has larger effects on achieving a third-order NLO response. The third-order NLO phenomenon of benzene ring complexes was experimentally studied at 532 nm using Z-scan technology, and some compounds showed the expected NLO properties.

The click products exhibit more NLO phenomena by performing different click combinations to the side groups, opening new perspectives on using the system in a variety of photoelectric applications.

To further provide some insight into mobile library (m-library) applications (apps) user needs and help libraries or app providers improve the service quality, the purpose of this paper is to explore all the types of user improvement needs and to discover which need is the most important based on user results.

Data were collected from more than 27,000 m-library app users from 16 provinces and autonomous regions in China. Text analysis using latent Dirichlet allocation and Word2Vec was carried out by text preprocessing. Furthermore, a visual presentation was conducted through pyLDAvis and word cloud. Finally, combined with expert opinions, the results were summarized to find the different types of needs.

There are three different types of needs for improvement: needs of function, needs of technology and needs of experience. These types can be further divided into six subtypes: richness of function, feasibility of function, easiness of technology, stableness of technology, optimization of experience and customization of experience. Besides the richness of function, the feasibility of function has received the most attention from users.

Most studies on m-library user needs have only focused on a method of quantitative research based on questionnaire surveys. This study, however, is the first to apply text mining methods for large-scale user opinion texts, which place more focus on user needs and inspire libraries and app providers to further improve their services.

Food safety risk brought by environmental pollution seriously threatens human health and affects national economic and social development. In particular, heavy metal pollution and nutrient deficiency have caused regional diseases. Thus, the purpose of this paper is to present a risk early warning method of food safety considering environmental and nutritional factors.

A novel risk early warning modelling method based on the long short-term memory (LSTM) neural network integrating sum product based analytic hierarchy process (AHP-SP) is proposed. The data fuzzification method is adopted to overcome the uncertainty of food safety detection data and the processed data are viewed as the input of the LSTM. The AHP-SP method is used to fuse the risk of detection data and the obtained risk values are viewed as the expected output of the LSTM. Finally, the proposed method is applied on one group of sterilized milk data from a food detection agency in China.

The experimental results show that compared with the back propagation and the radial basis function neural networks, the proposed method has higher accuracy in predicting the development trend of food safety risk. Moreover, the causal factors of the risk can be figured out through the predicted results.

The proposed modelling method can achieve accurate prediction and early warning of food safety risk, and provide decision-making basis for the relevant departments to formulate targeted risk prevention and control measures, thereby avoiding food safety incidents caused by environmental pollution or nutritional deficiency.

This study aims to address the issues of limited pipe diameter adaptability and low inspection efficiency of current pipeline inspection robots, a new type of pipeline inspection robot capable of adapting to various pipe diameters was designed.

The diameter-changing mechanism uses a multilink elastic telescopic structure consisting of telescopic rods, connecting rods and wheel frames, driven by a single motor with a helical drive scheme. A geometric model of the position relationships of the hinge points was established based on the two extreme positions of the diameter-changing mechanism.

A pipeline inspection robot was designed using a simple linkage agency, which significantly reduced the weight of the robot and enhanced its adaptive pipe diameter ability. The analysis determined that the robot could accommodate pipe diameters ranging from 332 mm to 438 mm. A static equilibrium equation was established for the robot in the hovering state, and the minimum pressing force of the wheels against the pipe wall was determined to be 36.68 N. After experimental testing, the robots could successfully pass a height of 15 mm, demonstrating the good obstacle capacity of the robot.

This paper explores and proposes a new type of multilink elastic telescopic variable diameter pipeline inspection robot, which has the characteristics of strong adaptability and flexible operation, which makes it more competitive in the field of pipeline inspection robots and has great potential market value.

The robot is characterized by the innovative design of a multilink elastic telescopic structure and the use of a single motor to drive the wheel for spiral motion. On the basis of reducing the weight of the robot, it has good pipeline adaptability, climbing ability and obstacle-crossing ability.

The eco-innovation is considered one of the possible ways to tackle climate change. However, the conflicting empirical evidence related to the role of eco-innovation on environmental quality becomes a motivation to explore the effect of eco-innovation on environmental degradation proxied by ecological footprint. Besides, it controls economic growth, remittance inflows, trade openness and total energy consumption in the environmental degradation function.

Uses the Augmented Auto Regressive Distributed Lag (AARDL) approach to examine the cointegration relation among the series during the period ranging from 1975 to 2017 for India within the environmental Kuznets curve (EKC) framework.

The result suggests that eco-innovation can mitigate climate change by reducing the ecological footprint. Similarly, economic growth reduces the ecological footprint in the short- and long-run. However, the square of economic growth is positive and significant. Thus, it shows evidence against the conventional EKC hypothesis. The results also reveal that remittance inflows have an insignificant negative role on the ecological footprint, while total energy consumption and trade openness harm the environment by enhancing the ecological footprint.

This study provides important implications for climate change mitigation. Thus, the government should promote eco-innovation to mitigate climate change by offering a favorable legal environment to the firms to adopt the same in their production and consumption activities. It also suggests that initiatives like green strategies should give serious attention while incurring research expenditure.

No prior studies assess the impact of eco-innovation on the ecological footprint for the period of 1975–2017 in India.

The purpose of this paper is to investigate the tribological properties of a textured lubricating wear-resistant coating modified by nano-SiC at a high temperature. Its aim is to explore the influence of a new composite method on the organisation and structure of sprayed coatings as well as the evolution rules governing their high-temperature tribological properties.

A KF301/WS2 lubricating, wear-resisting, coating was prepared on matrix material GCr15 by applying supersonic plasma spraying technology. On the basis of this sample, using nano-SiC particles as a filler, the KF301/WS2 nano-modified coating with its round, pit-type texture was prepared by laser re-melting technology and a surface texturing technique. Two kinds of coating micro-organisations and structures were examined by scanning electron microscopy, and the tribological properties of both the modified and conventional coatings were studied at a high temperature.

Results showed that nano-particles could effectively improve the coating micro-structure, and make the structure denser and more uniform, thus significantly increasing the wear resistance of the coating. When the friction and wear processes were stable, the friction coefficient decreased by 13 per cent, while the wear loss decreased by 45.9 per cent.

This research concentrating on the study of the process and performance of coatings doped with nano-particles by laser re-melting incorporating simultaneous surface texturing, and studies of their high-temperature tribological properties. That is because applying nano-particle modification technology to the development of wear-resistant coatings, and by applying the nano-particles to such coatings by thermal spraying technology, they can achieve a modification of the coating which makes the structure denser and more uniform.

Vehicular road traffic may represent an important soil and plant contamination source. In this context, the concentration of heavy metals (Cd, Pb, As, Sb, Ni, Cu, Fe, Al, Mn and Zn) and macronutrients (Ca, Mg, K and P) was evaluated in yerba mate (Ilex paraguariensis St. Hil.) cultivations and in soils adjacent to highways.

The investigated yerba mate cultivations were located in southern Brazil. Plant tissue (young and old leaves and branches) and soil (0–10 cm) samples were collected at five distances from the highway (0–10, 10–20, 20–30, 30–40 and 40–50 m). Plant tissue was analyzed with and without washing to evaluate contributions from particulate deposition.

Although increases in soil pseudo-total concentrations of Cd, Cu, Ni, Zn, Fe, Mn, Ca and Mg were observed only at the Erechim site, geoaccumulation indices and enrichment factors (EFs) did not indicate any heavy metal pollution. These results indicate the existence of natural variation in soil. Cadmium was more concentrated in branches than in leaves, while the opposite was observed for Pb. High levels of Mn and Al were found in foliar tissue. In summary, highway proximity did not lead to heavy metal contamination of yerba mate under the evaluated conditions.

This research explores the possibility of heavy metal pollution in plantations of yerba mate adjacent to highways and indicates natural concentrations of toxic elements that exceed current legislation, which was an important discovery regarding the yerba mate production chain.

The purpose of this paper is to investigate the effects of parallel texturing coating on antifriction mechanism of lubricating wear-resistant coating.

A KF301/WS2 lubricating wear-resisting coating was prepared on matrix material GCr15 by applying supersonic plasma spraying technology. On the basis of this sample, the KF301/WS2 modified coating with parallel pit-type texture was prepared by laser re-melting technology and a surface texturing technique. Their friction and wear behaviors were evaluated under ambient temperature, and the antifriction mechanism of two kinds of coatings were discussed.

Results showed that parallel texture has a certain impact on the tribological properties of the coating. When friction and wear reach stable state, the value of the friction coefficient of conventional coating was 0.115, while that of parallel texturing coating was 0.09, the latter decreased by 21 per cent. When the friction and wear time was up to 4 hours, the wear loss of the conventional coating was 0.29 mg, while that of the parallel texturing coating was 0.13 mg, the latter decreased by 55 per cent.

The tribological properties of parallel texturing coating were higher than conventional coating. That is because the change of three-body layer reduces the friction coefficient and the abrasive particles were collected by parallel texture, reducing the effects of debris.

Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such variations of materials, the properties of structure vary either lengthwise or thickness wise. This paper aims to investigate models for effective estimation of material properties, as it is necessary for industries to identify the properties of composites or functionally graded materials (FGM’s) before manufacturing and also to develop novel material combinations.

Available models were compared for different material combinations and tested with experimental data for properties such as Young’s modulus, density, coefficient of thermal expansion (CTE) and thermal conductivity. Combinations of metal–ceramic and metal–metal were selected such that their ratios cover a wide range of materials.

This study reveals different models will be required depending on the material used and properties to be identified.

The results of the present work will help researchers in the effective modeling of composites or FGM’s for any analysis.

This paper presents a comparison and review of various analytical methods with experimental data graphically to find out the best suitable method. For the first time, the Halpin-Tsai model was extended in the analysis of the CTE which shows good approximations.