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Automatic weeding is a hot research field of smart agriculture, which has many benefits such as achieving precise weed control, saving human cost, and avoiding damage on crops, etc. Recently, many researchers have focused on the research using the deep learning method, such as the convolutional neural network (CNN) and recurrent neural network (RNN) and have achieved decent outcomes related to the automatic weed detection. However, there are still generally problems of the projects such as weak robustness and excessive reliance on a large number of samples. To solve these problems, a recognition algorithm for automatic identification and weed removal was designed, and a soybean field weed detection and localization method based on the fusion of multiple image processing methods was proposed in this study. The images and video stream were obtained through the camera mounted on a mobile robot platform. Firstly, the soil background inside the image was segmented from the foreground (including the weeds and crops) by setting the threshold for a specific color space (hue). Then, three different methods including the area threshold method, template matching and saturation threshold method were used to classify the crops and weeds. Finally, based on a proposed innovative voting method, the three recognition methods were comprehensively weighed and fused to achieve more accurate recognition and localization results of the crops and weeds inside the image. Experimental validations were carried out using the samples obtained through the moving platform, and the experimental results showed that the average accuracy of the proposed weed detection algorithm was as high as 98.21%, while the recognition error was only 1.79%. Meanwhile, compared with each single method as the scale threshold, template matching and saturation threshold, the fused method based on the weighted voting has been able to raise the average accuracy by 5.71%. Even though the samples used in the validations were limited in covering different scenarios, the high recognition accuracy has proved the practicability of the proposed method. In addition, the robustness test that images with raindrop and shadow interference in the complex and unstructured agricultural scene was carried out, and satisfied results showed that above 90% of the plant were successfully detected, which verified the fine adaptability and robustness of the proposed method.

This paper reviewed the research progress in high-temperature-resistant modification of polycarbonate at home and abroad in recent years from two aspects: chemical and physical modifications. [ABSTRACT FROM AUTHOR]

In this study, we constructed domain D, E and DE truncated mutants of a marine-derived cyclodextrin glucosyltransferase (CGTase) my20 and heterologously expressed these mutants using the pET-24a vector and E. coli BL21 (DE3) as the host, and purified the expressed enzyme by nickel affinity column chromatography. The specific cyclization activities of my20ΔD, my20ΔE, and my20ΔDE were approximately 197%, 22%, and 17% of that of my20, respectively, indicating that domain E is important for the catalytic activity of CGTase, and the presence of domain D might hinder substrate molecules from entering the catalytic domains. my20 was a heat-resistant enzyme, and the three truncated mutants showed different degrees of reduction in heat resistance, suggesting that domains D and E played an important role in the heat resistance of CGTase. The domain DE-deleted mutant showed an 8% increase in the percentage of α-cyclodextrin (CD) in the catalytic product compared with the other truncated mutants, which suggested that the loss of domain DE affected the product specificity. The results of this study provide a theoretical basis for CGTase domain modification for its application in industrial production.

Si/SiO2 multilayers were fabricated by RF plasma enhanced chemical vapor deposition system, and phosphorus/ boron (P/B) co-doped silicon nanocrystals (Si NCs) were obtained under the constricted crystallization of multilayers structures. Microstructures of P/B co-doped Si NCs/SiO2 multilayers and impurities distributions were studied by Raman, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Low temperature electron paramagnetic resonance (EPR) results indicate that the non-radiative defects on Si NCs surfaces can be passivated by P and B impurities. Hall effect manifests that P and B impurities can substitutionally incorporate into Si NCs inner. Meanwhile, P impurity exhibits higher doping efficiency than B. Near-infrared photoluminescence near 1 200 nm with the wavelength compatible for optical telecommunication was detected in the small-sized P/B co-doped Si NCs. The emission intensity can be enhanced by regulating the nominal P-doping concentration. According to the time-resolved photoluminescence and EPR results, the physical mechanisms of P-doping on the radiative and non-radiative recombination processes of Si NCs were discussed, which are responsible for the enhancement of 1 200 nm photoluminescence. [ABSTRACT FROM AUTHOR]

Objective To investigate the intestinal mucosal function and the correlation between intestinal mucosal function and clinical indexes in elderly patients with acute exacerbation of moderate-to-severe chronic obstructive pulmonary disease （AECOPD）. Methods A total of 200 elderly patients with AECOPD were recruited in the study group, and 150 age- and sex-matched elderly patients with stable moderate and severe COPD were assigned into the control group. The clinical pulmonary infection score （CPIS） was assessed in the study group. The nutritional status was evaluated between two groups. Blood samples of all patients were collected for testing. The intestinal fatty acid binding protein （I-FBAP）, D-lactic acid, brain natriuretic peptide （BNP） and blood gas indexes were detected and compared between two groups. The correlation between I-FBAP, D-lactic acid, CPIS, BNP and blood gas indexes was analyzed. Results In the study group, the contents of I-FBAP, plasma D-lactic acid, BNP and PaCO2, and the incidence rate of malnutrition were significantly higher （all P < 0.05）, whereas pH and PaO2 were significantly lower （both P < 0.001） than those in the control group. In the study group, I-FBAP and D-lactic acid were negatively correlated with PaO2 （both P < 0.05）, whereas positively associated with malnutrition, CPIS and BNP （all P < 0.001）. D-lactic acid and I-FBAP were not correlated with pH and PaCO2 （all P > 0.05）. Conclusion Elderly patients with moderate-to-severe AECOPD are complicated with intestinal mucosal damage. The indexes of intestinal mucosal damage including D-lactic acid and I-FBAP are intimately associated with the severity of AECOPD, which can be used to evaluate the severity of AECOPD in clinical practice.

An improved layered adaptive image enhancement method is proposed by combining the Laplaeian pyramid mode and anisotropic filtering. First high dynamic range compression was realized by bilateral filter. Then Laplaeian pyramid model was adopted to decompose the image into a set of band pass filtered images. Moreover, an improved forward and backward anisotropic diffusion filtering algorithm (FBAD) was designed, which can adjust the diffusion parameters adaptively. Applying the FBAD filtering algorithm to layered band pass filtered images, through selecting different diffusing thresholds, the noise of image could be removed and the edges of the images be sharpened. Comparative study on experimental results of FBAD and other image enhancement algorithms shows the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of proanthocyanidins(PC) induced by amyloid-beta peptide(Aβ25-35) in human neuroblastoma cell line SH-SY5Y and its possible mechanism. Methods SH-SY5Y cells were exposed to Aβ25-35 to establish a cell injury model in vitro. PC and(or) secretory protein Dickkopf-1 (Dkk1), the endogenic inhibitor of Wnt/β-catenin signaling pathway were used for intervention. The cells were divided into control group, Aβ25-35 group, PC(different concentrations)+Aβ25-35 groups, Dkk1 group, Dkk1+ PC+Aβ25-35 group.The cell viability was evaluated by MTT assay. The expressions of β-catenin, GSK-3β, p-GSK-3β were measured by Western blot. The secreted Aβ1-42 was detected by ELISA. Results Compared with the control group, the cell viability, the expression of β-catenin and p-GSK-3β were reduced in Aβ25-35 treated group(P＜0.05), while the secreted Aβ1-42 was increased (P＜0.05). PC improved the cell viability, increased the expression of β-catenin and p-GSK-3β, and reduced the secreted Aβ1-42 in SH-SY5Y cells induced by Aβ25-35 (P＜0.05). After using Dkk1,the ability of PC was decreased on the enhancement of β-catenin expression, the improvement of p-GSK-3β expression, and the reduction of the secreted Aβ1-42 (P＜0.05). Conclusions PC may decrease Aβ1-42 secretion in SH-SY5Y cells induced by Aβ25-35 through Wnt/β-catenin signaling pathway.

Background: Immunoneoadjuvant therapy opens a new prospect for local advanced lung cancer. The aim of our study was to explore the safety and feasibility of robotic-assisted bronchial sleeve resection in patients with locally advanced non-small cell lung cancer (NSCLC) after neoadjuvant chemoimmunotherapy., Methods: Data of 13 patients with locally advanced NSCLC that underwent bronchial sleeve resection after neoadjuvant chemoimmunotherapy during August 2020 and February 2021 were retrospectively included. According to the surgical methods, patients were divided into thoracotomy bronchial sleeve resection (TBSR) group and robot-assisted bronchial sleeve resection (RABSR) group. Oncology, intraoperative, and postoperative data in the two groups were compared., Results: The two groups of patients operated smoothly, the postoperative pathology confirmed that all the tumor lesions achieved R0 resection, and RABSR group no patient was transferred to thoracotomy during surgery. Partial remission (PR) rate and major pathological remissions (MPR) rate of patients in the TBSR group were 71.43% and 42.86%, respectively. Complete pathological response (pCR) was 28.57%. They were 66.67%, 50.00% and 33.33% in RABSR group, respectively. There were no significant differences in operative duration, number of lymph nodes dissected, intraoperative blood loss, postoperative drainage time and postoperative hospital stay between the two groups, but the bronchial anastomosis time of RABSR group was relatively short. Both groups of patients had a good prognosis. Successfully discharged from the hospital and post-operative 90-d mortality rate was 0., Conclusions: In patients with locally advanced central NSCLC after neoadjuvant chemoimmunotherapy can achieve the tumor reduction, tumor stage decline and increase the R0 resection rate, bronchial sleeve resection is safe and feasible. Under the premise of following the two principles of surgical safety and realizing the tumor R0 resection, robot-assisted bronchial sleeve resection can be preferred.

To reveal the speciation and pollution status of heavy metal(loid) s (HMs) in the dewatered sewage sludge(SS) of municipal wastewater treatment plants(MWTPs) in China, SS samples were collected from 40 MWTPs located in different regions of China. The total concentrations and geochemical fractions of As, Cd, Cr, Cu, Ni, Pb, and Zn in the SS samples were analyzed. The ecological risks induced by HMs in the SS were assessed based on the toxicity characteristic leaching procedure(TCLP), risk assessment code(RAC), and potential ecological risk index(RI). The median values of HMs in SS followed the order Zn > Cu > Cr > Pb > Ni > As > Cd. The general attainment rates of HMs in SS were satisfactory(>90%). As showed a generally even distribution among all the fractions; Cd and Zn mainly existed in the reducible fraction; Cr mainly occurred in the residual fraction, followed by oxidizable and reducible fractions; Cu mainly occurred in the oxidizable fraction; Ni occurred mainly as exchangeable forms; and Pb mainly occurred in the reducible and residual fractions, with its exchangeable form being the lowest fraction. According to the RAC method, the environmental risks induced by HMs in the SS followed the order Ni > As > Zn > Cd > Cu > Cr > Pb. The ecological risk of Ni was high; Zn, As, and Cd had a medium level of risk; Cr and Cu had a low level of risk; and the risk of Pb was negligible. According to the RI method, Cd and Cu showed the highest potential ecological risk, indicating that these are the primary HM pollutants in the SS. However, if the agricultural application of SS is carried out in accordance with the national standards, the overall level of risk from soil HM pollution is considered relatively low.

In this paper, three representative varieties of peanut seeds were selected for the experiment based on visible/near-infrared reflectance spectroscopy living in the wavelength rang from 600 to 1 100 nm. Firstly, spectral datas ware collected by the near-infrared fiber optic spectrometer, and the spectral features of the original spectral dates were extracted by the wavelet analysis. Then the principal component analysis (PCA) was used for cluster analysis of spectral features. Finally, the four principal components were applied as the inputs, the varieties category as the output and the Mahalanobis distance as the discriminant function of the recognition model, so a linear discriminant analysis model was established. In the 50 samples of each varieties, 30 samples were randomly selected as the training set, and the remaining 20 samples as the predictor set. The recognition model for three peanut varieties have a recognition rate of 95% on average. As the experimental results show that this method is reliable and effectively, and a new method to distinguish and discriminate the quality of peanut seeds was put forword.

The present paper simulates laser wavelength 632 and 750 nm Gaussian beam migration in apple fruit tissue using Monte-Carlo method, and researches the spectral properties of absorption and scattering. It was shown that the special energy distribution characteristics of Gaussian beam influenced the diffusion of the laser in the tissue, the reflection, absorption and transmittance of 750 nm by tissue are lower, there are more photons interacting with tissue within the tissue, and they can more clearly reflect the information within the tissue. So, the transmission characteristics of the infrared light were relatively strong in biology tissue, which was convenient for researching biology tissue.