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The quality of agricultural products relates to the internal structure, which has long been a matter of interest in agricultural scientists. However, inspection methods of the opaque nature of internal information on agricultural products are usually destructive and require sample separation or preparation. X‐ray computed tomography (X‐ray CT) technology is one of the important nondestructive testing (NDT) technologies without sample separation and preparation. In this study, X‐ray CT technology is used to obtain two‐dimensional slice images and three‐dimensional tomographic images of samples. The purpose of the review was to provide an overview of the working principle of X‐ray CT technology, image processing, and analysis. This review aims to focus on the development of the agricultural products (e.g., wheat, maize, rice, apple, beef) and its applications (e.g., internal quality evaluation, microstructure observation, mechanical property measurement, and others) using CT scanner. This paper covers the aspects regarding the advantages and disadvantages of NDT technology, especially the unique advantages and limitations of X‐ray CT technology on the quality inspection of agricultural products. Future prospects of X‐ray CT technology are also put forward to become indispensable to the quality evaluation and product development on agricultural products.

Abstract:Confronted with severe frost damage to plants, methods, technologies and equipment have been developed and applied during the past century. The paper presents a comprehensive review on the most effective and active technology to protect plants from radiation frost based on air disturbance technology. The working principle of the technology was elaborated with frost protection mechanism, structures and applicability of three types of working patterns: conventional wind machines, selective inverted sink and portable vertical blowing. As an automatic mechanized technology, control strategy, applicable occasion and proper parameters are introduced for each type of working pattern. The operation of the technology and equipment depends on plant critical temperature, prevailing climatic conditions, thermal inversions strength, as well as costs. The frost protection performance and effectiveness of conventional horizontal wind machines, selective inverted sinks and helicopters are discussed and compared from the cost-effectiveness and application aspects, and the feasibility of selective inverted sinks is still controversial. Therefore, conventional wind machines are the best choice for plant frost protection and consequently are widely used in temperate and subtropical areas throughout the world. The frost protection application with helicopters is not easy to use during the frost nights with high cost. The paper also provides researchers with some perspectives on improving air disturbance technology and its equipment, and some practice recommendations for growers.

Recently, the World Health Organization ranked Narayanganj, Chittagong, and Dhaka among the top 25, 40, and 45 cities, respectively, for high ambient PM 2.5 concentrations. Bangladesh has instituted an air quality monitoring system operated by the Department of Environment. PM 2.5 and PM 10 were measured hourly from January 2014 through December 2017 in Dhaka, Gazipur, Narayanganj, Chittagong, Sylhet, and Barisal. All sites registered concentrations for both pollutants that exceeded the 24-h Bangladesh National Ambient Air Quality Standards. The particulate matter (PM) concentrations varied significantly seasonally and with different diel patterns from city to city. The highest concentrations were observed during the winter, typically when wind speeds and mixed layer heights are low and pollutant concentrations are increased by transport from the northwest. The PM 2.5 concentrations from the 1 st quarters of 2014 and 2015 were compared to assess whether political unrest that appeared to reduce vehicular moment to very low levels affected the observed values. However, the PM 2.5 concentrations were statistically similar at the Dhaka, Narayanganj, and Sylhet sites and different for the Gazipur, Chittagong, and Barisal locations. Thus, the PM 2.5 concentrations during the political unrest in the 1 st quarter of 2015 were not consistently lower across the measurement sites. These results indicate that vehicular emission contributions to PM 2.5 concentrations are smaller than in the past, which agrees with recent source apportionment studies showing that brick kilns have become the dominant source of PM.

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