Search

A fluorescence imaging system (FIS) supported by the excitation-emission matrix (EEM), has emerged as a powerful tool for the non-destructive assessment of fruit and vegetable quality, offering low costs and good accuracy for various applications. EEM captures the fluorescence spectrum under specific excitation light and the corresponding emission fluorescence, which can be used for optimizing machine vision construction. The FIS-EEM system can explore and identify naturally occurring bioactive and phytonutrient components whose fluorescent characteristics can be used non-destructively to monitor changes in the quality and maturation of fruits and vegetables. This review provides an in-depth analysis of the principles and methodologies of FIS based on EEM. By offering a comprehensive overview, this paper serves as a valuable reference for designing FIS for assessing fruit and vegetable quality. It also directs challenges and perspectives toward developing high-performance fluorescence imaging systems for research and commercial applications. [ABSTRACT FROM AUTHOR]

In this paper, porous ceramics with high porosity and low bulk density were prepared by using steel slag and kaolin as main raw materials and polyurethane sponge as template. The effects of steel slag particle size, zirconia addition, the solid content of the slurry, and the addition of polycarboxylic acid water-reducing agent on the properties of ceramics were studied. In addition, by adding a surfactant (Sodium dodecyl sulfate) to form fine pores on the original framework of the three-dimensional network porous ceramic, the shortcomings of the single as well as the uncontrollable density and porosity of the porous ceramic, which are produced by the template method, are improved. When the grinding time of steel slag is 90 min, the content of zirconia is 3% wt, the solid content of ceramic slurry is 64% wt, and 0.6% wt polycarboxylic acid water-reducing agent and 0.4% of surfactant are added, the prepared porous ceramic skeleton is clear and good. The porous ceramic has a low bulk density (as low as 157.869 kg/m3), high porosity (about 94.05%) and high compressive strength (0.2 MPa). The crystalline phase of it is mainly composed of anorthite, gehlenite, forsterite and quartz. The addition of zirconia, water-reducing agent and surfactant only changes the macrostructure of porous ceramics, and does not change its crystal phase composition. The preparation of porous ceramics from steel slag not only solves the recycling problem of steel slag, but also provides a good substitute for main raw materials of porous ceramics. [ABSTRACT FROM AUTHOR]

The strawberry (Fragaria × ananassa Duch.) is a popular fruit worldwide due to its attractive smell and good taste. However, a strawberry has a short postharvest life because of its fast deterioration, including softening. Until now, most sensing methods, like multispectral imaging and the electro nose sensor, were expensive. On the other hand, a non-destructive UV-induced fluorescence imaging method has the potential advantage of being low cost and detecting fruit quality changes in real-time. This research aims to establish a monitoring model for strawberry quality, especially firmness, using a machine vision system with UV LEDs for exciting fluorescence in the visible region. Strawberries were stored at 10 °C for 11 days in the experiment. Standard quality characteristics, firmness, and acidity, as well as fluorescence images and excitation-emission matrix (EEM) were captured during the experiment. Results showed that firmness decreased as storage time increased. The peak fluorescence intensity at wavelengths potentially be associated with amino acids and p-coumaric acid also increased during storage. The results of our analysis reveal a noteworthy correlation between the fluorescent component observed in Peak B of EEM measurements and firmness of strawberries during storage, as evidenced by a correlation coefficient of 0.89. These findings suggest that the aforementioned association may serve as a reliable index to estimate strawberry quality (firmness) over time. Furthermore, p-coumaric acid has a blue fluorescence in visible range when excited with 365 nm UV light. Thus, a machine vision system incorporating a cheap 365 nm UV LED light source and RGB camera could be developed to monitor strawberry quality decay during storage. To explore this possibility, the multiple color space from UV images of 77 strawberries were used to develop a estimation model for estimating the firmness of strawberry. The Partial Least-Squares Regression (PLSR) model showed the coefficient of determination R 2 in calibration, prediction and cross-validation were 0.82, 0.79 and 0.83, and corresponding Root Mean Square Error (RMSE) values were all 0.04. This study demonstrates that a low cost, real-time UV fluorescence imaging-based sensor system could be used to estimate strawberries' firmness during storage. • Fluorescence images were used for estimating strawberry storage quality. • Excitation-emission matrices were measured with storage time change. • Partial Least-Squares Regression for estimating firmness offered R 2 of 0.83. • Fluorescence images showed the potential for evaluating strawberry quality. [ABSTRACT FROM AUTHOR]

• Fluorescence images were used for early-stage detection of strawberry spoilage. • Firmness measurement was conducted to verify strawberry spoilage. • Excitation-emission matrices were measured to characterize fluorescence spectra. • The soon spoiled fruits were classified by fluorescence images in an early-stage. • The proposed method can provide a new indicator for evaluating strawberry quality. The soon spoiled strawberries need to be classified from healthy fruits in an early stage. In this research, a machine vision system is proposed for inspecting the quality of strawberries using ultraviolet (UV) light based on the excitation-emission matrix (EEM) results. Among the 100 fruits which were harvested and stored under 10 °C condition for 7 days, 7 fruits were confirmed to be spoiled by using a firmness meter. The EEM results show the fluorescence compound contributes to a whitish surface on the spoiled fruits. Based on the EEM results, UV fluorescence images from the bottom view of strawberries were used to classify the spoiled fruits and healthy fruits within 1 day after harvest. These results demonstrate the UV fluorescence imaging can be a fast, non-destructive, and low-cost method for inspecting the soon spoiled fruits. The proposed index related to the spoiling time can be a new indicator for qualifying strawberry. [ABSTRACT FROM AUTHOR]

Porous ceramics with high porosity and low bulk density were prepared by using nickel slag and metakaolin as the primary raw materials, glass powder as flux, and SiC as the foaming agent. The content of nickel slag and foaming agent had a significant effect on the bulk density, porosity, and flexural strength of the porous ceramics. The porous ceramics with the best properties were obtained at 1100 °C for 30 min with 50 wt% nickel slag, 40 wt% metakaolin, 10 wt% waste glass, and 0.8 wt% SiC. It had a low bulk density (as low as 245 kg/m3), high flexural strength and compressive strength (0.6 MPa and 1.17 MPa, respectively), and high porosity (about 89.8%). The nickel slag was magnetically separated as well. The density of nickel slag powder could be reduced via magnetic separation, and there was no significant change in the crystal structure of the raw material. Compared with porous ceramics prepared using nickel slag without magnetic separation, ceramics subjected to magnetic separation had lower bulk density, higher porosity, and the same phase composition. This study can be used as an indicator for the application of nickel slag in porous ceramics, which is of great significance in providing a great substitute nickel slag towards recovery and utilization. [ABSTRACT FROM AUTHOR]

• When silicate clinker was added, the strengths of FGD gypsum were increased. • Reducing the particle size of clinker can improve mechanical properties and water resistance. • Adding silicate clinker to FGD gypsum can reduce the hydration reaction rate With silicate clinker being added to FGD gypsum, calcium silicate and ettringite were formed. Silicate clinker was used to modify flue gas desulfurization (FGD) gypsum. Then the effects of the amount and particle size of silicate clinker on the mechanical properties, softening coefficient and water absorption of modified FGD gypsum materials were studied. The results show that adding a proper amount of silicate clinker could improve the water resistance and mechanical properties of FGD gypsum. When 6% of silicate clinker with average particle size of 26.83 μm was added, the dry flexural strength and dry compressive strength of FGD gypsum were 5.4 MPa and 10.7 MPa, respectively, 80% and 15% higher than those of pure FGD gypsum, respectively, and flexural softening coefficient and compressive softening coefficient reached 0.61 and 0.54, 52.5% and 58.8% higher than those of pure FGD gypsum, the water absorption rate was 28.5%, 17% lower than that of pure FGD gypsum. According to the microscopic characterization results, the improvement of the mechanical strength and water resistance of FGD gypsum after the addition of silicate clinker was due to the formation of a high-strength and insoluble C-S-H gel and ettringite on the surface of FGD gypsum crystals. [ABSTRACT FROM AUTHOR]