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"Li-Cheng, Yang"
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Stereoselective access to 5.5.0 and 4.4.1 bicyclic compounds through Pd-catalysed divergent higher-order cycloadditions
Medium-sized rings, including those embedded in bridged and fused bicyclic scaffolds, are common core structures of myriad bioactive molecules. Among various synthetic strategies towards their synthesis, intermolecular higher-order cycloaddition provides great potential to build complex medium-sized rings from simple building blocks. Unfortunately, such transformations are often plagued with competitive reaction pathways and low levels of site- and stereoselectivity. Herein, we report catalyst-controlled divergent access to three classes of medium-sized bicyclic compounds in high efficiency and stereoselectivity, by palladium-catalysed cycloadditions of tropones with γ-methylidene-δ-valerolactones. Mechanistic studies and density functional theory calculations disclosed that the divergent reactions stem from the different reaction profiles of the diastereomeric intermediates. While one undergoes either O- or C-allylation to provide [5.5.0] or [4.4.1] bicyclic compounds, the unique conformation of the other diastereomer allows an unconventional alkene isomerization to deliver bridgehead alkene-containing bicyclo[4.4.1] compounds. The conversion of these products to diverse complex polycyclic scaffolds has also been demonstrated.Using readily accessible tropones and γ-methylidene-δ-valerolactones, the divergent synthesis of three classes of challenging [5.5.0] or [4.4.1] bicyclic systems has been achieved—with high efficiency and stereoselectivity—through Pd-catalysed higher-order cycloaddition. Mechanistic studies and density functional theory calculations indicate that the divergent reactions arise from the different reactivity of two diastereomeric intermediates.
Journal Article
The impact of multi-person virtual reality competitive learning on anatomy education: a randomized controlled study
Background
Anatomy is one of the core subjects in medical education. Students spend considerable time and effort on learning the requisite anatomy knowledge. This study explored the effect of a multiple-player virtual reality (VR) gaming system on anatomy learning.
Methods
18 participants were randomly assigned into 3 learning conditions: (1) a textbook reading control group (CG), (2) a single-player VR (SP) group; and (3) a multiple-player VR (MP) group. The participants studied anatomy for 5 days, and completed a multiple-choice test on Days 1, 5, and 12. In the VR environment, the participants used handheld controllers to move the simulated tissues. The mission of the game was to complete puzzles of a human body. The SP and MP groups filled out a motivation inventory on Day 5. The scores on the multiple-choice test, the correct assembly rates, and the motivation inventory scores were analyzed using the 2-way ANOVA or independent
t
-test to compare group differences.
Results
There was a significant interaction effect of group and timepoint (
p
= 0.003) in the multiple-choice test. In the CG, the scores on Day 1, Day 5, and Day 12 were significantly different (
p
< 0.001). The scores on Day 5 were significantly higher than those on Day 1 (
p
< 0.001). Although the scores declined slightly on Day 12, they were still significantly higher than those on Day 1 (
p
< 0.001). The SP and MP groups had similar results (
p
< 0.001,
p
< 0.001). The differences between the groups were only significant on Day 12 (
p
= 0.003), not Day 5 (
p
= 0.06). On Day 12, the scores of the MP group were higher than those of the CG (
p
= 0.002). The SP group and MP group had high scores on the interest, competence, and importance subscales of the motivation inventory. Both VR groups considered the system to be fun and beneficial to their learning. However, the MP group reported higher stress levels than the SP group.
Conclusion
The results indicated that the proposed VR learning system had a positive impact on the anatomy learning. Although the between-player competition caused higher stress levels for the VR groups, the stress could have been a mediator of their learning outcomes.
Trial registration
ETRD, ETRD-D-19-00573. Registered 20 December 2018,
http://www.edah.org.tw/irb/index.htm
Journal Article
The Performance Investigation of Smart Diagnosis for Bearings Using Mixed Chaotic Features with Fractional Order
This article presents a performance investigation of a fault detection approach for bearings using different chaotic features with fractional order, where the five different chaotic features and three combinations are clearly described, and the detection achievement is organized. In the architecture of the method, a fractional order chaotic system is first applied to produce a chaotic map of the original vibration signal in the chaotic domain, where small changes in the signal with different bearing statuses might be present; then, a 3D feature map can be obtained. Second, five different features, combination methods, and corresponding extraction functions are introduced. In the third action, the correlation functions of extension theory used to construct the classical domain and joint fields are applied to further define the ranges belonging to different bearing statuses. Finally, testing data are fed into the detection system to verify the performance. The experimental results show that the proposed different chaotic features perform well in the detection of bearings with 7 and 21 mil diameters, and an average accuracy rate of 94.4% was achieved in all cases.
Journal Article
Genome-wide identification of maize G protein genes and regulatory roles of the ZmGG1 subfamily in saline-alkali stress response
Saline-alkaline stress is a major constraint in maize (
Zea mays
L.) production. Heterotrimeric G proteins play pivotal roles in plant stress responses. However, their functional mechanisms in maize under saline-alkaline stress remain poorly understood. This study aimed to characterize the maize G protein gene family and elucidate its regulatory mechanisms in response to saline-alkaline stress. Ten G protein genes (belonging to the Gα, Gβ, and Gγ subunit families) were identified from the maize genome using bioinformatics approaches. Their phylogenetic relationships, gene structures, promoter cis-acting elements, and protein-protein interaction (PPI) networks were systematically analyzed. Gene expression patterns in the saline-alkaline tolerant inbred line Zheng58 and the sensitive line Chang7-2 were investigated using qRT-PCR, alongside the determination of reactive oxygen species (ROS)-scavenging enzyme activities. The Gγ subfamily members (
ZmGG1
,
ZmGG3
, and
ZmGG5
) exhibited differential expression patterns. PPI network analysis revealed extensive interactions between G proteins and signaling components such as phospholipase C and MAP kinases. Under stress conditions, Chang7-2 displayed significant fluctuations in ROS-scavenging enzyme activity and accumulation of malondialdehyde (MDA). Therefore, this study elucidated the mechanism by which maize G proteins coordinate saline-alkaline stress responses through subfamily-specific expression regulation and intricate signaling networks, thereby providing potential candidate target genes for breeding stress-tolerant maize.
Journal Article
Steric‐Adaptive Biocatalysis: Imine Reductase‐Mediated Dynamic Kinetic Resolution for Atroposelective Synthesis of Hindered Biaryl Amines
As an efficient and environmentally benign strategy, enzymatic catalysis has emerged with high reactivity and selectivity for atropisomeric structures. Atropisomeric biaryl amines are of great importance in drug development and asymmetric catalysis. However, substrates with steric hindrance are often poorly accepted by enzymes, as the immense pockets required are not commonly found in wild‐type enzymes. In this work, an imine reductase (IRED)‐catalyzed dynamic kinetic resolution (DKR) strategy is introduced for the synthesis of atropisomeric biaryl amines, especially those with bulky substitutions on (hetero)aryls, including naphthalene‐ and quinoline‐containing biaryl scaffolds. A broad range of atropisomeric biaryl amines are obtained in up to 99% yield and 99% ee, enabled by the steric adaptability of IR‐09. Besides, a borrowing hydrogen cascade system is explored to extend the construction of atropisomeric biaryl amines directly from racemic alcohols. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations are carried out to elucidate the DKR process, selectivity of IR‐09, and interactions between the sterically hindered substrates and residues within the enzyme. An unusual IRED platform is reported, enabling efficient DKR via reductive amination without any evolutionary engineering. The system accommodates extremely sterically demanding substrates, including naphthyl and quinoline derivatives, delivering naphthyl‐aryl and quinoline‐aryl amine atropisomers with excellent efficiency and stereocontrol (over 80% yield and 90% ee for 14 examples out of 33 examples). This methodology significantly expands the accessible chemical space for biocatalytic atroposelective synthesis.
Journal Article
Simulation of a Submarine Landslide Using the Coupled Material Point Method
Exploring the submarine landslide is challenging due to the invisibility nature and the complex soil-water interaction and large deformation throughout its runout process. The purpose of this paper is to investigate the ability of the coupled material point method (MPM) in modeling the soil flows under water. A sand-column collapse experiment is performed fully under water initially, with the results used to benchmark the MPM analysis. Thereafter, the whole failure process of a real submarine landslide in the South Mediterranean sea is simulated using MPM. The results show that MPM can be a reliable tool in capturing the postfailure behaviors of the submarine landslide. The failure mode of the landslide is flow-type, with an initial translational slide moving to a diffusive one eventually.
Journal Article
HLA-B5801 Allele as a Genetic Marker for Severe Cutaneous Adverse Reactions Caused by Allopurinol
Allopurinol, a commonly prescribed medication for gout and hyperuricemia, is a frequent cause of severe cutaneous adverse reactions (SCAR), which include the drug hypersensitivity syndrome, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The adverse events are unpredictable and carry significant morbidity and mortality. To identify genetic markers for allopurinol-SCAR, we carried out a case-control association study. We enrolled 51 patients with allopurinol-SCAR and 228 control individuals (135 allopurinol-tolerant subjects and 93 healthy subjects from the general population), and genotyped for 823 SNPs in genes related to drug metabolism and immune response. The initial screen revealed strong association between allopurinol-SCAR and SNPs in the MHC region, including BAT3 (encoding HLA-B associated transcript 3), MSH5 (mutS homolog 5), and MICB (MHC class I polypeptide-related sequence B) ($P<10^{-7}$). We then determined the alleles of HLA loci A, B, C, and DRB1. The HLA-B*5801 allele was present in all (100%) 51 patients with allopurinol-SCAR, but only in 20 (15%) of 135 tolerant patients [odds ratio 580.3 (95% confidence interval, 34.4-9780.9); corrected P value=4.7× 10-24] and in 19 (20%) of 93 of healthy subjects [393.51 (23.23-6665.26); corrected P value=8.1× 10-18]. HLA alleles A*3303, Cw*0302, and DRB1*0301 were in linkage disequilibrium and formed an extended haplotype with HLA-B*5801. Our results indicated that allopurinol-SCAR is strongly associated with a genetic predisposition in Han Chinese. In particular, HLA-B*5801 allele is an important genetic risk factor for this life-threatening condition.
Journal Article
One-Pot Synthesis of Benzoxazole/Benzothiazole-Substituted Esters by Michael Addition: A Selective Construction of C-N/C-S Bonds
An efficient and convenient synthesis of benzoxazole/benzothiazole-substituted esters in a one-pot strategy is reported. In this investigation, a selective construction of C-N and C-S bonds via simple addition is performed. Thus, using substituted 2-aminophenols/2-aminobenzenethiols, TMTD (tetramethylthiuram disulfide) and α,β-unsaturated esters as starting substrates, C-N and C-S bonds can be selectively constructed by means of the Michael addition reaction. This protocol features high selectivity, high atomic economy, mild conditions, good functional tolerance and good to excellent yields, showing the potential value for the preparation of some biologically and pharmaceutically active compounds.
Journal Article
Research and comparison of algorithms based on multi-modal fusion
A multi-modal fusion algorithm is an important method for information fusion on multi-modal data provided by different sensors. It can make full use of the advantages of multiple sensors and improve the accuracy and robustness of data processing and decision-making. This paper aims to study the performance difference between the extended Kalman filter (EKF) algorithm and other algorithms in multi-modal fusion and explore a method to fuse multiple algorithms further to improve the accuracy of fusion results. The author uses the classic test set data set for experiments to evaluate the performance of different algorithms. By comparing and analyzing the performance of each algorithm in data fusion tasks, we can get their advantages and disadvantages in different scenarios. Among them, the extended Kalman filter algorithm is a classical algorithm based on Bayesian filtering, which can estimate the system state through recursive state estimation and covariance update. In addition, the author also uses linear regression, random forest, and other algorithms to compare. Then, the author uses several test sets to evaluate the performance of each algorithm. Through a comprehensive analysis of the MSE and MAE errors output by the algorithm, the applicability, advantages, and disadvantages of each algorithm in different scenarios are obtained.
Journal Article