► Application of NO at 25μll−1 was effective in reducing CI of cucumber fruit. ► NO improved the antioxidative defence system of cucumber in cold stress. ► NO improved DPPH-radical scavenging ...activity of cucumber in cold stress.
Cucumber fruit were pre-treated with 25μll−1 nitric oxide (NO) for 12h at 20°C, and then stored at 2±1°C and 95% relative humidity for 15days. Chilling injury index, membrane permeability, lipid peroxidation, superoxide anion (O2-) production rate, H2O2 content, activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and DPPH-radical scavenging activity were measured. The results showed that the application of NO at 25μll−1 was most effective in reducing CI in cucumber fruit. The treatment reduced the increases in membrane permeability and lipid peroxidation, delayed the increases in both O2- production rate and H2O2 content. The NO-treated fruit exhibited significantly higher activities of SOD, CAT, APX and POD and higher DPPH-radical scavenging activity than control fruit during the storage. The overall results suggest that NO enhanced chilling tolerance in cucumber fruit by improving the antioxidative defence system.
Visual Simultaneous Localization and Mapping (visual SLAM) has attracted more and more researchers in recent decades and many state-of-the-art algorithms have been proposed with rather satisfactory ...performance in static scenarios. However, in dynamic scenarios, the performance of current visual SLAM algorithms degrades significantly due to the disturbance of the dynamic objects. To address this problem, we propose a novel method which uses optical flow to distinguish and eliminate the dynamic feature points from the extracted ones using RGB images as the only input. The static feature points are fed into the visual SLAM system for the camera pose estimation. We integrate our method with the original ORB-SLAM system and validate the proposed method with the challenging dynamic sequences from the TUM dataset and our recorded office dataset. The whole system can work in real time. Qualitative and quantitative evaluations demonstrate that our method significantly improves the performance of ORB-SLAM in dynamic scenarios.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The effects of nitric oxide (NO) on browning and lignification of bamboo shoots were investigated. Bamboo shoots were dipped for 1
h in 0.5
mM sodium nitroprusside (SNP), a nitric oxide donor, then ...packed in 0.01
mm thick polyethylene bags, and stored for 10 days at 10
°C. SNP treatment inhibited activities of PPO, POD and PAL and maintained high total phenol contents, thus delaying external browning during storage. Furthermore, SNP treatment showed a significant inhibition of the synthesis of lignin and cellulose and delayed tissue lignification, indicating that application of NO may be a promising method for extending shelf-life and maintaining quality of peeled bamboo shoots.
Complex environments pose great challenges for autonomous mobile robot navigation. In this study, we address the problem of autonomous navigation in 3D environments with staircases and slopes. An ...integrated system for safe mobile robot navigation in 3D complex environments is presented and both the perception and navigation capabilities are incorporated into the modular and reusable framework. Firstly, to distinguish the slope from the staircase in the environment, the robot builds a 3D OctoMap of the environment with a novel Simultaneously Localization and Mapping (SLAM) framework using the information of wheel odometry, a 2D laser scanner, and an RGB-D camera. Then, we introduce the traversable map, which is generated by the multi-layer 2D maps extracted from the 3D OctoMap. This traversable map serves as the input for autonomous navigation when the robot faces slopes and staircases. Moreover, to enable robust robot navigation in 3D environments, a novel camera re-localization method based on regression forest towards stable 3D localization is incorporated into this framework. In addition, we utilize a variable step size Rapidly-exploring Random Tree (RRT) method which can adjust the exploring step size automatically without tuning this parameter manually according to the environment, so that the navigation efficiency is improved. The experiments are conducted in different kinds of environments and the output results demonstrate that the proposed system enables the robot to navigate efficiently and robustly in complex 3D environments.
Sweetpotato is prone to disease caused by C. fimbriata without obvious lesions on the surface in the early period of infection. Therefore, it is necessary to explore the possibility of developing an ...efficient early disease detection method for sweetpotatoes that can be used before symptoms are observed. In this study, sweetpotatoes were inoculated with C. fimbriata and stored for different lengths of time. The total colony count was detected every 8 h; HS-SPME/GC–MS and E-nose were used simultaneously to detect volatile compounds. The results indicated that the growth of C. fimbriata entered the exponential phase at 48 h, resulting in significant differences in concentrations of volatile compounds in infected sweetpotatoes at different times, especially toxic ipomeamarone in ketones. The contents of volatile compounds were related to the responses of the sensors. E-nose was combined with multiple chemometrics methods to discriminate and predict infected sweetpotatoes at 0 h, 48 h, 64 h, and 72 h. Among the methods used, linear discriminant analysis (LDA) had the best discriminant effect, with sensitivity, specificity, precision, and accuracy scores of 100%. E-nose combined with K-nearest neighbours (KNN) achieved the best predictions for ipomeamarone contents and total colony counts. This study illustrates that E-nose is a feasible and promising technology for the early detection of C. fimbriata infection in sweetpotatoes during the asymptomatic period.
During fresh-cut processing, potatoes lose their inherent protective cellular structure, leading to enzymatic browning that compromises sensory and edible quality. Tea polyphenols (TPs), natural ...preservatives with potent reducing properties, are hypothesized to impact this browning process. However, their influence and regulatory mechanism on the enzymatic browning of fresh-cut potatoes remain poorly understood. This study used the "Holland Seven" potato as the research material to explore the effects of a treatment with different TP concentrations (0.1 g L
, 0.2 g L
, and 0.3 g L
) on the browning phenomenon and quality of fresh-cut potatoes during storage. The results showed that appropriate concentrations of TP treatment had a good preservation effect on the appearance and edible quality of fresh-cut potatoes. Furthermore, exogenous TP treatment reduced the content of enzymatic browning substrates (caffeic acid, p-coumaric acid, and ferulic acid) by regulating phenylpropanoid metabolism. Meanwhile, TP treatment augmented the activities of antioxidative enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase), maintained higher levels of ascorbic acid (Vc), and reduced glutathione (GSH). Consequently, the TP treatment could inhibit enzymatic browning by regulating reactive oxygen species (ROS) metabolism and the Vc-GSH cycle in fresh-cut potatoes.
This letter describes a pipeline for autonomous object search using a mobile robot. The robot is required to efficiently find an object in an unknown environment. In this letter, we formulate the ...object-search problem as a Partially Observable Markov Decision Process (POMDP). The semantic information of the room types and the object is utilized for training the belief distribution in the POMDP. We use Gaussian Mixed Model (GMM) to model the distribution of belief states. This letter introduces a novel scheme for the belief propagation when the robot is searching for an object. Both the belief distribution trained by the prior knowledge and the searching experience of the robot are taken into consideration when a new room turns up. The objective function in our formulation concerns both the path cost to the target and the information gain in the target area. We propose a novel graph structure called belief road map (BRM) that is built along with the searching process. The robot can efficiently query a path on the generated BRM instead of on the whole occupancy grid map. To reduce the belief states in the POMDP, the node in BRM that has the most information is selected to represent a room. The simulation and the real experimental studies demonstrate the efficiency and efficacy of our proposed searching approach.
Ellis & Halsted is the pathogen causing black rot in sweet potatoes that can lead to flavor change and toxin release. This study detected the volatile organic compounds (VOCs) of
-infected sweet ...potatoes in the early stages using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 55 VOCs were identified, including aldehydes, alcohols, esters, ketones, and others. The content of aldehydes and ketones showed a decreasing trend, while alcohols and esters showed an increasing trend. An increase in infection time elevated the content of malondialdehyde (MDA) and pyruvate, while the starch content decreased, the content of soluble protein initially increased, then decreased, and the activities of lipoxygenase (LOX), pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), and phenylalanine ammonia-lyase (PAL) increased. The changes in VOCs were closely related to the content of MDA, starch, pyruvate, and the activities of LOX, PDC, ADH, and PAL. Sweet potatoes showed a good discrimination effect by principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) from 0 to 72 h. Twenty-five differential VOCs could be used as early-stage characteristic compounds of
-infected sweet potatoes for early disease monitoring.
► NO fumigation preserved better quality of Chinese bayberry. ► NO treatment induced higher activities of antioxidant enzymes and antioxidant capacity. ► NO might prevent decay by reducing ROS and ...ethylene.
Chinese bayberry fruit were fumigated with 20μll−1 NO for 2h at 20°C, then stored at 1±0.5°C and 90% relative humidity for 10 days. Postharvest disease incidence, ethylene production, fruit firmness, membrane permeability, lipid peroxidation, H2O2 contents, rate of superoxide anion (O2−) production, antioxidant enzymes activities, and antioxidant ability were determined after storage. The results showed that fumigation with NO inhibits ethylene production and disease incidence, and delay the decrease in firmness, total phenolics contents and DPPH radical-scavenging activity in Chinese bayberry fruits. NO treatment reduced the increases in membrane permeability and lipid peroxidation, delayed the increases in both the rate of O2− production and H2O2 contents, and increased activities of SOD, CAT and APX. These results indicate that NO might maintain the balance between the formation and detoxification of ROS, enhance the resistance of tissues to decay and preserve better quality of Chinese bayberries.
Multi-robot environmental coverage can be widely used in many applications like search and rescue. However, it is challenging to coordinate the robot team for high coverage efficiency. In this paper, ...we propose a Two-Stage Coordination (TSC) strategy, which consists of a high-level leader module and a low-level action executor. The former provides the robots with the topology and geometry of the environment, which are crucial for robots to learn "where" they should go and avoid invalid coverage. Based on the observed information and the environmental topology, the latter module takes primitive action to reach the sub-goal. To facilitate cooperation among the robots, we aggregate local perception information of neighbors from different hops based on graph neural networks. We compare our method with state-of-the-art multi-robot coverage approaches. Experiments and supporting ablation studies show the superior efficiency, scalability, and generalization of our algorithm especially in unseen style and scale of scenes, and an unseen number of robots.
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