Robot teams are increasingly being deployed in environments, such as manufacturing facilities and warehouses, to save cost and improve productivity. To efficiently coordinate multi-robot teams, fast, ...high-quality scheduling algorithms are essential to satisfy the temporal and spatial constraints imposed by dynamic task specification and part and robot availability. Traditional solutions include exact methods, which are intractable for large-scale problems, or application-specific heuristics, which require expert domain knowledge to develop. In this paper, we propose a novel heterogeneous graph attention network model, called ScheduleNet, to learn scheduling policies that overcome the limitations of conventional approaches. By introducing robot- and proximity-specific nodes into the simple temporal network encoding temporal constraints, we obtain a heterogeneous graph structure that is nonparametric in the number of tasks, robots and task resources or locations. We show that our model is end-to-end trainable via imitation learning on small-scale problems, and generalizes to large, unseen problems. Empirically, our method outperforms the existing state-of-the-art methods in a variety of testing scenarios involving both homogeneous and heterogeneous robot teams.
Asymmetric Total Synthesis of (+)-Waihoensene Qu, Yongzheng; Wang, Zheyuan; Zhang, Zhongchao ...
Journal of the American Chemical Society,
04/2020, Letnik:
142, Številka:
14
Journal Article
Recenzirano
The asymmetric total synthesis of (+)-waihoensene, which has a cis-fused 6,5,5,5 tetracyclic core bearing an angular triquinane, a cis-fused six-membered ring, and four contiguous quaternary carbon ...atoms, was achieved through a sequence of chemical reactions in a stereochemically well-defined manner. The total synthesis features the following: (1) Cu-catalyzed asymmetric conjugated 1,4-addition; (2) diastereoselective Conia-ene type reaction; (3) diastereoselective intramolecular Pauson–Khand reaction; (4) Ni-catalyzed diastereoselective conjugated 1,4-addition; and (5) radical-initiated intramolecular hydrogen atom transfer (HAT). Control experiments and density functional theory calculations support the proposed HAT process.
We developed an efficient visible-light-mediated formal carbene insertion reaction of 1,3-diketones with diazoesters for the construction of enantioenriched 1,4-dicarbonyl compounds with a quaternary ...carbon center. Combining visible light and a Brønsted acid catalyst, chiral 1,4-dicarbonyl compounds were achieved in good yields with high enantioselectivities by a photochemical carbene transfer protocol.
An efficiently stereoselective 4 + 2 cycloaddition of 3-alkylenyloxindoles and α-diazoketones through sequential visible-light photoactivation and
-heterocyclic carbene catalysis was achieved. A ...series of tetrahydropyrano2,3-
indoles with an all-carbon quaternary stereocenter were obtained in good yields with excellent diastereo- and enantioselectivities.
Whether fecal microbiota transplantation (FMT) in patients with irritable bowel syndrome (IBS) is effective in improving outcomes remains controversial. We assessed the safety and efficacy of FMT for ...patients with IBS.
In this systematic review and meta-analysis, we searched PubMed, Embase, Web of Science, the Cochrane Library, the clinicaltrials.gov and International Clinical Trials Registry Platform (ICTRP) up to February 25, 2022, updated to March 28, 2023. Randomized controlled trials (RCTs) compared the stool and capsule FMT with placebo in patients with IBS were included. Two authors independently assessed study eligibility, extracted the data, and assessed risk of bias. We did meta-analysis with RevMan, and the Stata software was used for sensitivity analysis and meta-regression. The GRADE system was used to assess the quality of evidences. Mean difference (MD) or standardized Mean difference (SMD) with 95% CI for continuous data, and risk ratios (RR) with 95% CI for dichotomous data were used with random-effects models. The primary outcomes included the clinical response rate and IBS-SSS score. This study is registered with PROSPERO: CRD42022328377.
Nineteen reports from nine RCTs were included finally. Compared with the placebo, a single stool FMT could significantly decrease the IBS-SSS score at 1 month (MD=-65.75, 95%CI -129.37, -2.13), 3 months (MD=-102.11, 95% CI -141.98, -62.24), 6 months (MD=-84.38, 95%CI -158.79, -9.97), 24 months (MD=-110.41, 95%CI -145.37, -75.46), and 36 months (MD=-104.71, 95%CI -137.78, -71.64). It also could improve the clinical response rate at 3 months (RR=1.91, 95% 1.12, 3.25), 24 months (RR=2.97, 95% 1.94, 4.54), and 36 months (RR=2.48, 95% 1.65, 3.72), and increase the IBS-QoL score at 3 months, 24 months, and 36 months. FMT did not increase the serious adverse event. The risk of bias was low, and the quality of evidence based on GRADE system was moderate in the stool FMT group. However, we did not find positive effect of capsule FMT on patients with IBS based on the current available data.
A single stool FMT is effective and safe for patients with IBS. However, some factors may affect the effectiveness of FMT, and the relationship between the gut microbiome and the effect of FMT for IBS is still unclear.
https://www.crd.york.ac.uk/prospero/, identifier CRD42022328377.
In flowering plants, RNA editing is a post-transcriptional process that selectively deaminates cytidines (C) to uridines (U) in organellar transcripts. Pentatricopeptide repeat (PPR) proteins have ...been identified as site-specific recognition factors for RNA editing. Here, we report the map-based cloning and molecular characterization of the defective kernel mutant
in maize. Loss of
function leads to delayed embryogenesis and endosperm development, which produce small and collapsed kernels.
encodes an E+-type PPR protein targeted to the mitochondria, which is required for RNA editing of mitochondrial NADH dehydrogenase 3 at the
-317 and
-44 sites. Biochemical analysis of mitochondrial protein complexes revealed a significant reduction in the mitochondrial NADH dehydrogenase complex I activity, indicating that the alteration of the amino acid sequence at
-44 and
-317 through RNA editing is essential for NAD3 function. Moreover, the amino acids are highly conserved in monocots and eudicots, whereas the events of C-to-U editing are not conserved in flowering plants. Thus, our results indicate that
is essential for RNA editing of
, which is critical for NAD3 function, mitochondrial complex I stability, and seed development in maize.
Gastric cancer is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Understanding the factors influencing the therapeutic effects in gastric cancer patients and the ...molecular mechanism behind gastric cancer is still facing challenges. In addition to genetic alterations and environmental factors, it has been demonstrated that epigenetic mechanisms can also induce the occurrence and progression of gastric cancer. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressor complex 2 (PRC2), which trimethylates histone 3 at Lys-27 and regulates the expression of downstream target genes through epigenetic mechanisms. It has been found that EZH2 is overexpressed in the stomach, which promotes the progression of gastric cancer through multiple pathways. In addition, targeted inhibition of EZH2 expression can effectively delay the progression of gastric cancer and improve its resistance to chemotherapeutic agents. Given the many effects of EZH2 in gastric cancer, there are no studies to comprehensively describe this mechanism. Therefore, in this review, we first introduce EZH2 and clarify the mechanisms of abnormal expression of EZH2 in cancer. Secondly, we summarize the role of EZH2 in gastric cancer, which includes the association of the EZH2 gene with genetic susceptibility to GC, the correlation of the EZH2 gene with gastric carcinogenesis and invasive metastasis, the resistance to chemotherapeutic drugs of gastric cancer mediated by EZH2 and the high expression of EZH2 leading to poor prognosis of gastric cancer patients. Finally, we also clarify some of the current statuses of drug development regarding targeted inhibition of EZH2/PRC2 activity.
This work performed a theoretical investigation to explore the mechanism and reactivity of the Co-mediated intramolecular Pauson-Khand reaction for constructing bicyclo-skeletons.
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The ...Co2(CO)8-mediated intramolecular Pauson-Khand reaction is an efficient approach for constructing polycyclic skeletons. Recently, some of us reported a series of this type reactions involving sterically-hindered enynes for synthesizing natural products with reasonable reaction rates and yields. However, the reason for the high reactivity of the reaction remains unclear. We employed density functional theory calculations to clarify the mechanism and reactivity for this reaction. In contrast with chain olefin reactants, CO insertion is considered to be the rate-determining step for the overall Pauson-Khand reaction of cyclooctene derivatives. The reduced activation free energy for the alkene insertion step is attributed to: i) the electron-withdrawing group in close proximity to the CC triple bond enhancing the reactivity of the alkyne moiety; ii) lower steric hindrance during alkene insertion when using the cyclooctene derivative. The effect of the substituent on the Co2(CO)8-mediated intramolecular Pauson-Khand reaction was then investigated. Internal alkenes exhibit lower reactivity than terminal alkenes because of the steric hindrance introduced by the substituted group. The cis internal alkene exhibits higher reactivity than the trans internal alkene. An ester group in close proximity to the CC triple bond significantly enhances the reactivity.
Aim. Portal hypertension is a series of syndrome commonly seen with advanced cirrhosis, which seriously affects patient’s quality of life and survival. This study was designed to access the efficacy ...and safety of selective esophagogastric devascularization in the modified Sugiura procedure for patients with cirrhotic hemorrhagic portal hypertension. Methods. Sixty patients with hepatitis B cirrhotic hemorrhagic portal hypertension and meeting the inclusion criteria were selected and randomly divided by using computer into the selective modified Sugiura group (sMSP group, n = 30) and the modified Sugiura group (MSP group, n = 30). The primary endpoint measurement is the postoperative rebleeding rate. Secondary endpoint measurements included free portal venous pressure, liver Child–Pugh score, liver volume, portal vein width and blood flow velocity, survival rate, quality of life, and dysphagia as well as other complications one year postoperatively. This trial is registered with ChiCTR, number ChiCTR2000033468. Results. There was no statistically significant difference in rebleeding rates within one year after surgery between patients in the sMSP and MSP groups (χ = 0.11, p=0.73). In comparison with the MSP group, the Child–Pugh score of liver function in the sMSP group significantly increased (χ = 6.4, p=0.04) and the incidence of dysphagia was significantly reduced (χ = 6.23, p=0.01) one year after surgery. There was a statistically significant difference in the quality of life between the two groups. However, there were no statistically significant differences in free portal venous pressure (MD = −3.44, 95% CI: −7.87 to 0.98, p=0.12), postoperative liver volume (3 months: MD = -258.81, 95% CI: −723.21 to 205.57, p=0.24; 1 year: MD = −320.12, 95% CI: −438.43 to 102.78, p=0.16), postoperative portal vein width (3 months: MD = −0.06, p=0.50; 1 year: MD = 0.17, p=0.21), portal vein flow velocity (3 months: MD = 1.64, p=0.21; 1 year: MD = −1.19, p=0.57), 1-year survival rate (χ = 1.01, p=0.31), and other complications between the two groups. Conclusions. Selective esophagogastric devascularization in the modified Sugiura procedure may not lower the incidence of rebleeding in the short term based on our findings. However, it may significantly improve quality of life of patients with cirrhotic hemorrhagic portal hypertension, improve liver function, and reduce postoperative dysphagia.
To prevent vehicles running off road, road edge detection is a fundamental function. Current work on road edge detection has not exhaustively tackled all weather and illumination conditions. In this ...paper, we first sort roads under various illuminations. Then, data mining is applied to a large driving video set to learn the qualitative and statistical distribution of road edge appearances. The corresponding features are selected for robust road edge detection. To visualize road appearance and evaluate the accuracy of detected road, a compact road profile image is generated from video data. Through the examination of all weather and illumination conditions, our road detection methods can locate road edges in good weather, reduce errors in dark illuminations, and report road invisibility in poor illumination.
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