No abstract

Weeds in agricultural farms are aggressive growers which compete for nutrition and other resources with the crop and reduce production. The increasing use of chemicals to control them has inadvertent consequences to the human health and the environment. In this work, a novel neural network training method combining semantic graphics for data annotation and an advanced encoder–decoder network for (a) automatic crop line detection and (b) weed (wild millet) detection in paddy fields is proposed. The detected crop lines act as a guiding line for an autonomous weeding robot for inter-row weeding, whereas the detection of weeds enables autonomous intra-row weeding. The proposed data annotation method, semantic graphics, is intuitive, and the desired targets can be annotated easily with minimal labor. Also, the proposed “extended skip network” is an improved deep convolutional encoder–decoder neural network for efficient learning of semantic graphics. Quantitative evaluations of the proposed method demonstrated an increment of 6.29% and 6.14% in mean intersection over union (mIoU), over the baseline network on the task of paddy line detection and wild millet detection, respectively. The proposed method also leads to a 3.56% increment in mIoU and a significantly higher recall compared to a popular bounding box-based object detection approach on the task of wild–millet detection.

Self-expandable metal stent (SEMS) placement is commonly used for palliation of left-sided malignant colorectal obstruction (MCO). However, right-sided MCO is usually treated surgically. Recent studies that compared palliative SEMS insertion and emergency surgery in right-sided MCOs have reported conflicting results. This study aimed to compare the effectiveness of palliative SEMS placement in left-sided MCOs and right-sided MCOs and to investigate the predictive factors for clinical success and risk factors for complications. Data from 469 patients who underwent palliative SEMS placement for MCO at 6 hospitals in the Honam province of South Korea between 2009 and 2018 were reviewed. Among them, 69 patients with right-sided MCO and 400 patients with left-sided MCO who underwent SEMS placement for palliative purposes were enrolled. Clinical success, overall survival, complications, and predictive factors for clinical success and risk factors for complications were included as the main outcome measures. The clinical success rates were 97.1% (65/67) in right-sided MCO patients and 88.2% (353/400) in left-sided MCO patients. Complications including stent migration, tumor ingrowth, outgrowth, perforation, bacteremia/fever, and bleeding occurred in 10.1% (7/69) of right-sided MCO patients and 19.9% (79/400) of left-sided MCO patients. The mean overall survival of right-sided MCO was 28.02 months and 18.23 months for left-sided MCO. In multivariate logistic regression analysis, T3 stage tumors and the use of uncovered stents were significant factors for the clinical success of SEMS. The use of covered stents and performance status score of 0 to 2 were independent significant risk factors for complications. Palliative SEMS placement in right-sided MCO showed better clinical success rates than left-sided MCO. The use of uncovered stents is recommended for higher clinical success rates and lower complication rates.

A recently rising question of the applicability of two-dimensional (2D) materials to membranes of enhanced performance in water technology is drawing attention increasingly. At the center of the attention lies graphene, an atom-thick 2D material, for its readiness and manufacturability. This review presents an overview of recent research activities focused on the fundamental mass transport phenomena of two feasible membrane architectures from graphene. If one could perforate pores in a pristine impermeable graphene sheet with dimensional accuracy, the perforated 2D orifice would show unrivaled permeation of gases and liquids due to the 0D atomic barrier. If possibly endowed with selectivity, the porous graphene orifice would avail potentially for membrane separation processes. For example, it is noteworthy that results of molecular dynamics simulations and several early experiments have exhibited the potential use of the ultrathin permeable graphene layer having sub-nanometer-sized pores for a water desalination membrane. The other membrane design is obtainable by random stacking of moderately oxidized graphene platelets. This lamellar architecture suggests the possibility of water treatment and desalination membranes because of subnanometric interlayer spacing between two adjacent graphene sheets. The unique structure and mass transport phenomena could enlist these graphene membrane architectures as extraordinary membrane material effective to various applications of membrane technology including water treatment. Graphic abstract

There has been increased use of self-expandable metal stents (SEMS) in treating malignant colorectal obstruction (MCO). The aim of this study was to investigate factors that are associated with the outcomes of SEMS placement for MCO. Clinical data from patients who underwent SEMS placement for MCO at 6 hospitals in Honam province of South Korea between 2009 and 2018 were reviewed retrospectively. Eight hundred two patients were identified and their data were analyzed. Technical success, clinical success, complications, and predictors of outcome were included as main outcome measures. Technical and clinical success rates were 98.8% (792/802) and 90.1% (723/802), respectively. Complications including stent migration, stent occlusion due to tumor ingrowth and outgrowth, perforation, bacteremia/fever, and bleeding occurred in 123 (15.3%) patients. In multivariate regression analyses, procedure time was significantly associated with the technical success of SEMS placement ( P = .001). Longer length of obstruction, the use of covered stent, and longer procedure time were significant independent predictive factors for the clinical success of SEMS placement (odds ratio [OR] 0.974 (95% confidence interval [CI] 0.950–0.990); P = .043, OR 0.255 (95% CI 0.138–0.471); P < .001, and OR 0.957 (95% CI 0.931–0.984); P = .002, respectively). Stage IV colorectal cancer and the use of covered stent were significant independent predictive factors for the development of complications after SEMS placement (OR 2.428 (95% CI 1.407–4.188); P = .001 and OR 3.329 (95% CI 2.060–5.378); P < .001, respectively). Longer length of obstruction, the use of covered stent, and longer procedure time were associated with lower clinical success rates. Having stage IV colorectal cancer and the use of covered stents were associated with an increased risk of complications.