Palladium-catalyzed dipolar cycloaddition reactions represent an efficient strategy for the construction of cyclic compounds, with the development of novel dipolar precursors being a key focus. In this study, a new type of dipolar precursor was synthesized through the assembly of the vinylethylene carbonate unit and the tetrahydronaphthalene skeleton. This dipolar precursor can undergo [3 + 2], [5 + 4], and [5 + 2] cycloaddition reactions, leading to the construction of tetrahydronaphthalene-fused oxazolidin-2-ones, 1,5-oxazonines, and tetrahydrooxepines.
View Article and Find Full Text PDFThe construction of medium-sized ring compounds has been a prominent research area in synthetic chemistry. In this study, we developed a tandem strategy that combines allylic amination and ring-opening of oxetanes to synthesize medium-sized heterocycles. Specifically, -aryl oxetan-3-amines undergo allylic amination with zwitterionic π-allylpalladium, followed by intramolecular ring-opening, resulting in the formation of medium-sized heterocycles.
View Article and Find Full Text PDFLigand-directed divergent synthesis (LDS) is an important synthetic tool for the preparation of structurally diverse organic molecules without tedious steps to modify substrates. Herein, we introduce the realization of 3,4-, 1,2-, and 1,4-cyclization of benzo[]isothiazole-1,1-dioxide-fused azadienes (BDAs) through LDS, leading to tetrahydro-2-pyrans, oxazinanes, and tetrahydro-2-1,5-oxazocines, respectively. Using phosphinooxazoline (PHOX) ligands, we have developed a [4 + 2] cycloaddition between BDAs and substituted 2-alkylidenetrimethylene carbonates, providing access to multi-substituted chiral tetrahydro-2-pyrans in good yields with excellent enantio-, diastereo-, and regioselectivities.
View Article and Find Full Text PDFPurpose: The purpose of this study was to investigate the precision of deep learning (DL)-based auto-reconstruction in localizing interstitial needles in post-operative cervical cancer brachytherapy (BT) using three-dimensional (3D) computed tomography (CT) images.
Material And Methods: A convolutional neural network (CNN) was developed and presented for automatic reconstruction of interstitial needles. Data of 70 post-operative cervical cancer patients who received CT-based BT were used to train and test this DL model.
While asymmetric insertion of metal carbenes into H-X (X = C, N, O, ) bonds has been well-established, asymmetric control over free carbenes is challenging due to the presence of strong background reactions and lack of any anchor for a catalyst interaction. Here we have achieved the first photo-induced metal-free asymmetric H-X bond insertion of this type. With visible light used as a promoter and a chiral phosphoric acid used as a catalyst, α-diazoesters and aryl amines underwent smooth N-H bond insertion to form enantioenriched α-aminoesters with high efficiency and good enantioselectivity under mild conditions.
View Article and Find Full Text PDF. The purpose of this study was to evaluate the accuracy of brachytherapy (BT) planning structures derived from Deep learning (DL) based auto-segmentation compared with standard manual delineation for postoperative cervical cancer..
View Article and Find Full Text PDFAn efficient cascade approach for the construction of nitrogen-containing polycyclic compounds from amines tethered with an alkenyl (or alkynyl) group and divinyl carbonates is described. In the presence of Pd(0)-catalyst, an active zwitterionic allylpalladium species is generated and undergoes allylic amination with various amines followed by Diels-Alder reaction to form various polycyclic -heterocyclic products, including hydrophenanthridines, hydrobenzo[]azepines (hydro)isoindoles and hydrobenzo[]indoles.
View Article and Find Full Text PDFChem Commun (Camb)
September 2022
A new approach for the synthesis of 9-membered N,N,O-heterocycles by Pd-catalyzed [6+3] dipolar cycloaddition of -iminoisoquinolinium ylides and 2-vinyl oxetanes has been developed. The scope of this cycloaddition was demonstrated with 28 examples. This is another important synthetic strategy for medium-sized rings by employing -iminoisoquinolinium ylides as ternary synthons.
View Article and Find Full Text PDFDeep learning (DL) based approach aims to construct a full workflow solution for cervical cancer with external beam radiation therapy (EBRT) and brachytherapy (BT). The purpose of this study was to evaluate the accuracy of EBRT planning structures derived from DL based auto-segmentation compared with standard manual delineation. Auto-segmentation model based on convolutional neural networks (CNN) was developed to delineate clinical target volumes (CTVs) and organs at risk (OARs) in cervical cancer radiotherapy.
View Article and Find Full Text PDFSpecific social media behaviors have been found to be differentially associated with adjustment outcomes; however, the extant research has yet to consider the motivations behind why adolescents engage in these specific behaviors. This study examined the role of two developmentally relevant motivational correlates (social goals and pubertal status) on four social media behaviors (self-disclosure, self-presentation, social monitoring, and lurking) and two time-based measures of social media use (daily number of hours on social media and frequency of social media use). Self-report data were collected from 426 middle-school students (54.
View Article and Find Full Text PDFCyclopropanes embedded in a polycyclic bridged architecture are a versatile structural motif, but such complex frameworks often impose substantial synthetic challenges. Herein we introduce a new approach for the expedient access to such spring-loaded strained systems via an exceptionally mild intermolecular convergent process between the readily available isobenzopyryliums and vinyl boronic acids. Different from the typical conventional approaches, our protocol does not involve the highly active carbenoid intermediates or strong conditions in order to overcome the disfavored kinetic and thermodynamic problems.
View Article and Find Full Text PDFJ Youth Adolesc
December 2021
Social media engagement is common among adolescents, yet not all adolescents use social media in the same ways or experience the same adjustment correlates. This study examined four social media behaviors (self-disclosure, self-presentation, lurking, and social monitoring) and two time-based measures of social media use (daily number of hours on social media and frequency of social media use) on three developmentally relevant adjustment correlates (internalizing problems, prosocial support, and online peer victimization). Self-report data were collected from 426 middle-school students (54.
View Article and Find Full Text PDFZhongguo Dang Dai Er Ke Za Zhi
September 2020
Objective: To investigate the clinical features and outcome of neonatal acute respiratory distress syndrome (ARDS) in southwest Hubei, China.
Methods: According to the Montreux definition of neonatal ARDS, a retrospective clinical epidemiological investigation was performed on the medical data of neonates with ARDS who were admitted to Department of Neonatology/Pediatrics in 17 level 2 or level 3 hospitals in southwest Hubei from January to December, 2017.
Results: A total of 7 150 neonates were admitted to the 17 hospitals in southwest Hubei during 2017 and 66 (0.
Peer victimization is a pervasive problem for early adolescents, yet not all victims experience the same adjustment difficulties. The prominence of peer social relationships during adolescence suggests that peer-related factors (e.g.
View Article and Find Full Text PDFObjective: To investigate the incidence of neonatal asphyxia and possible contributing factors for the development of severe asphyxia in Hubei Enshi Tujia and Miao Autonomous Prefecture, China.
Methods: A total of 16 hospitals in Hubei Enshi Tujia and Miao Autonomous Prefecture were selected as research centers. A retrospective analysis was performed for the clinical data of 22 294 live births in these 16 hospitals from January to December, 2016 to investigate the incidence rate of neonatal asphyxia and possible contributing factors for the development of severe asphyxia.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi
October 2018
The progression of glioblastoma (GBM) is driven by dynamic alterations in the activity and connectivity of gene pathways. Revealing these dynamic events is necessary in order to understand the pathological mechanisms of, and develop effective treatments for, GBM. The present study aimed to investigate dynamic alterations in pathway activity and connectivity across radiotherapy and chemoradiation conditions in GBM, and to give system‑level insights into molecular mechanisms for GBM therapy.
View Article and Find Full Text PDFSocial groups across species rapidly self-organize into hierarchies, where members vary in their level of power, influence, skill, or dominance. In this review, we explore the nature of social hierarchies and the traits associated with status in both humans and nonhuman primates, and how status varies across development in humans. Our review finds that we can rapidly identify social status based on a wide range of cues.
View Article and Find Full Text PDFWe explored the effects of 3 group features (i.e., status, cohesion, and ethnic composition) on socialization processes of aggression in early adolescents' natural peer social groups.
View Article and Find Full Text PDFThe transition to middle school often presents behavioral and academic challenges to youths. Boys of color (i.e.
View Article and Find Full Text PDFDev Psychol
February 2014
The effect of popularity goal on the use of 3 popularity-related behaviors and later popularity status was examined in a diverse sample of 314 6th-grade students (176 girls and 138 boys) in both fall (Time 1) and spring (Time 2) semesters. Popularity goal and the use of popularity-driven behaviors (e.g.
View Article and Find Full Text PDFAlthough numerous investigations of overt aggressive and antisocial trajectories have been undertaken, there is a dearth of literature examining gender differences and similarities in trajectory patterns and their correlates. To address these gaps, we investigated gender differences in the prevalence rates, predictive validity during transition to adulthood, childhood risk factors, and adolescent correlates of different trajectories of teacher-reported overt aggression (i.e.
View Article and Find Full Text PDFPorcine parvovirus (PPV) is the major causative agent in a syndrome of reproductive failure in swine. Much has been learned about the structure and function of PPV in recent years, but nothing is known about the epitopes of the structural protein VP1, which is an important antigen of PPV. In this study, the monoclonal antibody C4 against VP1 of PPV was prepared and was used to biopan a 12-mer phage peptide library three times.
View Article and Find Full Text PDFOpen-ended questions were used to obtain narrative accounts of what makes a girl (or a boy) popular (or unpopular) at school. The participants were 489 African American students in Grades 1, 4, and 7 recruited from high-risk inner-city neighborhoods. Appearance and self-presentation were mentioned the most in Grades 4 and 7.
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