Asymmetric Synthesis of Trisubstituted Vicinal Diols through Copper(I)-Catalyzed Diastereoselective and Enantioselective Allylation of Ketones with Siloxypropadienes.

Chiral trisubstituted vicinal diols are a type of important organic compounds, serving as both common structure units in bioactive natural products and chiral auxiliaries in asymmetric synthesis. Herein, by using siloxypropadienes as the precursors of allyl copper(I) species, a copper(I)-catalyzed diastereoselective and enantioselective reductive allylation of ketones was achieved, providing both syn-diols and anti-diols in good to excellent enantioselectivity. DFT calculations show that cis-γ-siloxy-allyl copper species are generated favorably with either 1-TBSO-propadiene or 1-TIPSO-propadiene. Moreover, the steric difference of TBS group and TIPS group distinguishes the face selectivity of acetophenone, leading to syn-selectivity for 1-TBSO-propadiene and anti-selectivity for 1-TIPSO-propadiene. Easy transformations of the products were performed, demonstrating the synthetic utility of the present method. Moreover, one chiral diol prepared in the above transformations was used as a suitable organocatalyst for the catalytic asymmetric reductive self-coupling of aldimines generated in situ with B2(neo)2.

The application of radiomics in esophageal cancer: Predicting the response after neoadjuvant therapy.

Esophageal cancer (EC) is one of the fatal malignant neoplasms worldwide. Neoadjuvant therapy (NAT) combined with surgery has become the standard treatment for locally advanced EC. However, the treatment efficacy for patients with EC who received NAT varies from patient to patient. Currently, the evaluation of efficacy after NAT for EC lacks accurate and uniform criteria. Radiomics is a multi-parameter quantitative approach for developing medical imaging in the era of precision medicine and has provided a novel view of medical images. As a non-invasive image analysis method, radiomics is an inevitable trend in NAT efficacy prediction and prognosis classification of EC by analyzing the high-throughput imaging features of lesions extracted from medical images. In this literature review, we discuss the definition and workflow of radiomics, the advances in efficacy prediction after NAT, and the current application of radiomics for predicting efficacy after NAT.

A novel web-based dynamic nomogram for recurrent laryngeal nerve lymph node metastasis in esophageal squamous cell carcinoma.

Background: Patients with esophageal squamous cell carcinoma (ESCC) are liable to develop recurrent laryngeal nerve (RLN) lymph node metastasis (LNM). We aimed to assess the predictive value of the long diameter (LD) and short diameter (SD) of RLN lymph node (LN) and construct a web-based dynamic nomogram for RLN LNM prediction. Methods: We reviewed 186 ESCC patients who underwent RLN LN dissection from January 2016 to December 2018 in the Affiliated Hospital of North Sichuan Medical College. Risk factors for left and right RLN LNM were determined by univariate and multivariate analyses. A web-based dynamic nomogram was constructed by using logistic regression. The performance was assessed by the area under the curve (AUC) and Brier score. Models were internally validated by performing five-fold cross-validation. Results: Patients who underwent left and right RLN LN dissection were categorized as left cohort (n = 132) and right cohort (n = 159), with RLN LNM rates of 15.9% (21/132) and 21.4% (34/159), respectively. The AUCs of the LD (SD) of RLN LN were 0.663 (0.688) in the left cohort and 0.696 (0.705) in the right cohort. The multivariate analysis showed that age, the SD of RLN LN, and clinical T stage were significant risk factors for left RLN LNM (all P < 0.05), while tumor location, the SD of RLN LN, and clinical T stage were significant risk factors for right RLN LNM (all P < 0.05). The dynamic nomograms showed reliable performance after five-fold cross-validation [(left (right), mean AUC: 0.814, range: 0.614-0.891 (0.775, range: 0.084-0.126); mean Brier score: 0.103, range: 0.084-0.126 (0.145, range: 0.105-0.206)], available at https://mpthtw.shinyapps.io/leftnomo/ and https://mpthtw.shinyapps.io/rightnomo/. Conclusion: The LD and SD of RLN LN are inadequate to predict RLN LNM accurately, but online dynamic nomograms by combined risk factors show better prediction performance and convenient clinical application.

Gate-controlled reversible rectifying behaviour in tunnel contacted atomically-thin MoS2 transistor.

Atomically thin two-dimensional semiconducting materials integrated into van der Waals heterostructures have enabled architectures that hold great promise for next generation nanoelectronics. However, challenges still remain to enable their applications as compliant materials for integration in logic devices. Here, we devise a reverted stacking technique to intercalate a wrinkle-free boron nitride tunnel layer between MoS2 channel and source drain electrodes. Vertical tunnelling of electrons therefore makes it possible to suppress the Schottky barriers and Fermi level pinning, leading to homogeneous gate-control of the channel chemical potential across the bandgap edges. The observed features of ambipolar pn to np diode, which can be reversibly gate tuned, paves the way for future logic applications and high performance switches based on atomically thin semiconducting channel.Van der Waals heterostructures of atomically thin materials hold promise for nanoelectronics. Here, the authors demonstrate a reverted stacking fabrication method for heterostructures and devise a vertical tunnel-contacted MoS2 transistor, enabling gate tunable rectification and reversible pn to np diode behaviour.