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Abstract A method of near-infrared spectroscopy combined with wavelet transform was proposed to determine in-situ the gel time and gel point of epoxy resin simultaneously. The reconstructed spectra of the low-frequency wavelet coefficients were used for determination of gel time, and the reconstructed spectra of some detail coefficients which are dominated by chemical information for determination of epoxy conversion. In-situ determination of gel point has been achieved using evolutionary near infrared spectra of epoxy curing. The accuracy of gel point achived to 0.01. Compared with the traditional determination method of gel point, in which TMA and DSC are respectively used for gel time and conversion, this method not only can determine in-situ gel time and conversion degree simultaneously, and remarkably improve accuracy of the gel point result but also is of low cost, and fast and easy to operate. Highlights • Gel time and gel point of epoxy curing can be determined simultaneously by in situ NIR spectroscopy combined with WT. • Accuracy of gel point has been remarkably improved using the reconstructed NIR spectra by WT detail coefficient. • Gel time can be easily monitored using the reconstructed NIR spectra by WT approximate coefficient. • The epoxy curing reaction has been interpreted at molecular level using the evolutionary NIR spectra. • The NIR method is obviously superior to the method of DSC combined with TMA because of low cost, fast and easy to operate. [ABSTRACT FROM AUTHOR]

• A novel approach for spectral standardization by cosine spectra (cosSSM) is proposed. • CosSSM effectively eliminates the inter-channel spectral differences. • CosSSM improves the applicability of the channel-specific PLS model with performance better or comparable to well-established PDS method. • CosSSM is relatively simple and easy-to-implement in practical application. To tackle the issue that the multivariate calibration model cannot be shared among channels due to the inter-channel spectral differences in the on-line multi-channel spectrometer, taking the determination of octane number (RON) and aromatic hydrocarbon content (AC) of multiple reformulated gasoline by on-line Fourier transform near-infrared (FT-NIR) spectrometer combined with partial least squares (PLS) as an example, a novel approach for spectral standardization by piecewise cosine spectra (cosSSM) is proposed in this paper. A total of 42 reformulated gasoline samples were collected and their RON and AC were determined using standard methods with their NIR absorption spectra being measured using the three channels of an on-line NIR spectrometer, respectively. To prove the effectiveness of cosSSM, the spectra of each channel were standardized using cosSSM, and the PLS models of RON and AC were established using the cosine spectra in one channel, then the predictions of the cosine spectra in the other channels were made. The results suggested that cosSSM effectively eliminated the adverse effect of inter-channel spectral variation on the applicability of the channel-specific PLS model, and the performance was comparable to that of the well-established piecewise direct standardization (PDS) method. Besides, cosSSM is relatively simple and easy-to-implement in practical application. [ABSTRACT FROM AUTHOR]

Returning sloping farmland (>25°) to forest/grassland (RFTF) is an effective ecological measure for soil and water conservation. However, changes in nutrient cycles and green development are still unclear. Ningxia, in Northwestern China, began to implement RFTF in 2000. Here, we used the NUFER model to calculate the input and loss of nitrogen and phosphorus, utilization efficiency, production and consumption at food-chain scale in Ningxia for the period 1985–2015. Five aspects comprised the evaluation of green development: society, economy, resources, environment, and productivity. Results showed that forest coverage rate increased from 7.74% to 33.2%, while cropping area decreased by 6.6%. NH 3 loss increased from 53,000 to 83,000 tons (56%), N 2 O increased from 1200 to 2300 tons (92%) and leaching loss from 18,000 to 62,000 tons (240%). Phosphorus leaching loss increased from 13,000 to 35,000 tons (130%). The environmental cost of food nitrogen per unit of production decreased from 8 to 6.7 kg/kg (19.4%). Nitrogen and phosphorus use efficiencies decreased by 4.8% and 58% in crops-animal systems, respectively, but increased by 652% and 430% in animal husbandry systems. The proportion of animal protein production increased from 18.3% to 39.0% (113%). The major source of organic waste was livestock and poultry manure and urine (70%). Indicators for achieving green development level increased from 14 to 18 (14.7%). Improving the level of scientific and technological management of aquaculture system, increasing the proportion of organic matter returned to farmlands, and paying attention to the combination of planting and breeding will effectively promote future cycling efficiency of nitrogen and phosphorus in the food chain, and the sustainability of agriculture towards green development. Unlabelled Image • Returning farmland to forestry/grassland effectively conserves soil and water. • Changes in nutrient cycles and green development are still unclear. • N and P flows and use efficiency changes over 30 years studied at food-chain scale. • N P input and feed import into farming and animal husbandry systems have increased. • Dietary structure changes have increased plant and animal food product export. [ABSTRACT FROM AUTHOR]

• A novel SR method was proposed for rapid determination of asphalt properties. • SR method well overcome the drawbacks of commonly used modeling methods. • Asphalt properties were predicted accurately by ATR-FTIR combined with SR method. • The new method has been successfully used in the pavement construction of highway. Determining wax content, softening point, and penetration of asphalt products by traditional methods is too time-consuming to meet the instant need in practice. Although infrared spectroscopy combined with multivariate calibration may realize rapid determination of asphalt, its modeling and maintenance are very labor-intensive and challenging. In this paper, a novel method combining attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) with a fast algorithm of spectrum representation (SR) was proposed to rapidly and expediently determine the properties. The proposed method achieves calibration-free, effectively overcoming the drawback of the modeling methods. The feasibility of the new method was demonstrated using 431 asphalt samples produced by different kinds of crude oil. The root mean standard error of prediction (RMSEP) of wax content, softening point, and penetration by SR method are 0.14%, 0.55 °C and 4.71 (0.1 mm), respectively. Each of them is below the reproducibility of corresponding standard test method. Moreover, the new method is compared with other two commonly used methods, partial least squares regression (PLS) and local modeling by densification (LMD), in detail. The results show that the new method not only can solve the disadvantages of PLS modeling effectively, but also is remarkably superior to LMD method, in repeatability and speed, and robustness for predicting the sample in the region with lower density and unreasonable distribution of the samples in data bank. [ABSTRACT FROM AUTHOR]

• NIR spectroscopy was used to determine pure cashmere content without drying. • Spectral reconstruction method was proposed to retrive valuable physical information in NIR spectra. • Moisture elimination combing spectral reconstruction method improves prediction accuracy. • The RMSEP achieved 5.18% for moisture-containing scoured cashmere. Pure cashmere content (PCC) is a key parameter for assessing the quality of scoured cashmere. The traditional manual analytical method is quite laborious and time-consuming. A novel method has been developed by using near-infrared (NIR) spectroscopy combined with chemometrics and other mathematical methods. The accuracy of PCC calibration model, which is of great importance in practical application, remains a challenge due to the fact that the NIR diffuse reflectance spectra of scoured cashmere are badly influenced by absorbed moisture and light scattering. To improve the prediction accuracy, moisture elimination was first adopted to decrease the adverse effect of moisture on the spectra by subtracting the spectral contribution of water from the raw spectra. Spectral reconstruction was subsequently designed to take full advantage of the information contained in the residual values obtained after multiplicative scatter correction (MSC) pretreatment to retrieve the light scatter signal correlated with the physical properties of pure cashmere. Both the above two methods can improve the prediction performance of the partial least-squares regression (PLSR) model, and their combination can achieve the optimal model with root mean of square error of prediction (RMSEP) of 5.18 %, which satisfy the accuracy requirement for PCC measurement. The proposed method is rapid, low-cost, and environment-friendly for evaluating the quality of scoured cashmere fibers and shed light on the NIR-based analysis of the complex systems with valuable physical information. [ABSTRACT FROM AUTHOR]

• Reactivity of primary and secondary amines in epoxy curing process was determined by NIR spectroscopy combined with multivariate analysis. • The wavelet-based second derivative and angle vector transform were combined to effectively eliminate the effect on MCR by scattering light. • Reactivity of primary is different from that of secondary amines during epoxy curing process. • There is a competitive reaction with epoxy group between PA and SA, their competitiveness can be quantitatively expressed by k 2(SA) /k 2(PA). The temperature of epoxy curing reaction and the change of amino reactivity for the amine curing agent have an effect on the three-dimensional network structure of the product, which in turn affect the performance of the epoxy resin. The study on the reactivity and kinetics of primary and secondary amines in epoxy curing process is of great significance to deeply understand the curing mechanism and realize the control of product quality. In this paper, an effective method for studying the reactivity and kinetics of primary and secondary amines in epoxy curing process by near-infrared (NIR) spectroscopy combined with multivariate analysis was proposed. The curing system of bisphenol A epoxy resin (E51) and M-xylylenediamine (MXDA) was studied, and the resins were isothermally prepared at 50, 60, 70, 80, 90 °C, respectively. The NIR spectra of the system for each curing reaction process were continuously collected online. The characteristic absorption bands of the primary and secondary amines overlap heavily in the wavenumber range of 6700–6330 cm−1. The wavelet-based second derivative together with multivariate curve resolution(MCR) were employed to resolve their respective absorption peaks. Then, the curves of conversion and conversion rate for primary and secondary amines were obtained. The study shows that the kinetics of the curing reaction follows the self-catalytic Kamal model in the early stage, and it follows the revised model of incorporating the diffusion factor after vitrification, in which the hydroxyl group plays a self-catalytic role in the reaction process; the reactivity of primary and secondary amines is different during epoxy curing process. There is a competitive reaction between them, and its competitiveness can be expressed by k 2(SA) /k 2(PA) ; the reactivity of primary and secondary amines varies with curing temperature, and k 2(SA) /k 2(PA) increases significantly when curing temperature exceeds 60 °C, which has a significant influence on the formed resin network structure. [ABSTRACT FROM AUTHOR]

Rapid identification of cashmere textiles using near-infrared (NIR) spectroscopy chronically has been limited by the high spectral similarity of cashmere and wool, moisture interference, and the deficiency of existing spectral pattern recognition methods. A novel drying-free method of NIR spectroscopy combined with an adaptive representation learning-based classification algorithm and moisture-containing samples preparation was proposed to tackle the issue. The diffused reflectance NIR spectra of textile samples with different colors, different textures, and varying moisture contents were collected. The Soft Independent Modeling by Class Analogy (SIMCA), the Support Vector Machine (SVM) and the new method were compared to build the cashmere identification models of the dried samples and the moisture-containing samples, respectively. The effects of common spectral pretreating methods and moisture variation on the identification of cashmere textiles were studied in detail. The performance of the new approach is much superior to others when identifying moisture-containing samples, an accuracy for cashmere textiles, 93.33% and one for the cashmere-wool blend, 96.60% achieved, respectively. This fruit has been integrated with a portable NIR-based textile analyzer and successfully applied to identify the real-world textiles free of drying. This research is of great practical significance to the market supervision and the production of cashmere textiles. • NIR spectroscopy was used to identifying cashmere textiles without drying. • A more precise spectral pattern recognition method has been proposed. • The classification accuracy achieved 93.33% for moisture-containing cashmere textiles. • A portable textiles analyzer based on the new method was developed. [ABSTRACT FROM AUTHOR]

Phenolic acids are mainly released from plant residue decomposition and play important roles in the assembly of the soil microbiome. Understanding the general features of soil microbial communities modulated by phenolic acids could provide fundamental insights into the assembly of the soil microbiome. We analyzed the effects of four phenolic acids (ferulic acid, phthalic acid, salicylic acid and tannic acid) on the soil fungal communities at two concentrations. Despite the application of different phenolic acids to the soil, we were able to identify certain general changes in the fungal communities. We found that the tested phenolic acids significantly increased the deterministic assembly process of the fungal community but decreased the fungal diversity. Moreover, the fungal community structure under each tested phenolic acid treatment was distinct at low concentrations but similar at high concentrations. Salicylic acid had the greatest impacts on the fungal community. In addition, Fusarium and Aspergillus were significantly enriched in the soil amended with all the tested phenolic acids at high concentrations. Our study revealed certain general changes in the soil fungal communities modulated by phenolic acids, which deepened our understanding of the fungal assembly mechanism and provided robust insights for identifying candidate phenolic acid-degrading microbes. [ABSTRACT FROM AUTHOR]

The bacteria that dominate and become enriched in the rhizosphere during continuous cropping are of increasing interest, as they can greatly adapt to the rhizosphere. However, there are still little knowledge about the general composition and function of these bacteria. In this study, we planted tomatoes in three different soils for three planting cycles and used both high-throughput sequencing and culture-dependent workflows. Despite significant differences in bacterial communities from the initial soils, we observed a similar succession in the rhizosphere bacterial community compositions. We identified certain bacteria that were gradually enriched and potentially beneficial, such as Rhizobium and Flavobacterium. However, some other potentially beneficial bacteria, such as Massilia and Lysobacter, were gradually depleted. Additionally, we found that predicted functions related to xenobiotic biodegradation, nutrient metabolism and antibiotic biosynthesis were enriched in different rhizosphere soils. Beijerinckia fluminensis GR2, which was gradually enriched in all tested soils, significantly inhibited the growth of Ralstonia solanacearum and protected the host from infection. Our study provides new insights into the assembly mechanism of gradually enriched bacteria and their role as plant-beneficial microbes that adapt well to the rhizosphere. [ABSTRACT FROM AUTHOR]

Real time detection of free formaldehyde content during synthesis process of phenolic resins is of great significance for controlling the quality of resin products. In this paper, we proposed a method of near infrared (NIR) spectroscopy combined with multivariate curve resolution-alternating least squares (MCR-ALS) to online real time detect free formaldehyde content during the synthesis process of phenolic resins. The absorption band of CH bonds in formaldehyde was extracted by MCR-ALS from the overlapped absorption bands of CH bonds in phenol, formaldehyde and intermediate products, and is directly utilized to monitor free formaldehyde content during polymerization process. The calculated results of MCR-ALS are highly consistent with those obtained by the chemical titration method, which indicates this method is accurate. Compared with multivariate calibration commonly used for NIR, this method does not require modeling, and is more labor-saving and easier to spread in industrial production. • A new method for online determination of free formaldehyde content during polymerization of phenolic resins is presented. • This new method is achieved by using NIR spectroscopy combined with a modeling-free method. • The NIR CH absorption band of formaldehyde is extracted by MCR-ALS from the overlapped CH absorption bands. • The extracted CH band of formaldehyde can directly and accurately monitor the free formaldehyde content. • The method is modeling-free and obviously superior to the commonly used multivariate calibration modeling method. [ABSTRACT FROM AUTHOR]

Inspired by the growing demand for smart and environmentally friendly polymer materials, we employed 2,2′-disulfanediyldianiline (22DTDA) as a chain extender to synthesize a waterborne polyurethane (WPUR). Due to the ortho-substituted structure of the aromatic disulfide, the urea moieties formed a unique microphase structure in the WPUR, its mechanical strength was enhanced more 180 times relative to that of the material prepared without 22DTDA, and excellent self-healing abilities at body temperature in air or under ultrasound in water were obtained. If the self-healing process was carried out at 37 °C, 50 °C or under ultrasound, the ultimate tensile strength and elongation at break of the healed film could reach 13.8 MPa and 1150%, 15.4 MPa and 1215%, or 16 MPa and 1056%, respectively. Moreover, the WPUR films could be re-healed at the same fracture location over three cutting–healing cycles, and the recovery rates of the tensile strength and elongation at break remained almost constant throughout these cycles. [ABSTRACT FROM AUTHOR]