For seeking high enantiopurity, the previously reported thermal asymmetric catalysis is usually carried out at low temperature sometimes with limited yield, that is, the high enantiomeric excess (ee) ...usually at the cost of high yield. Thus, the achieving both high stereoselectivity and yield is an enormous challenge. We report herein two metal nanoparticle (M NP)-loaded and porphyrin-containing homochiral covalent organic framework (CCOF)-based composite catalysts, and their application in the thermally-driven asymmetric one-pot Henry and A
-coupling reactions. All the reactions are conducted at elevated temperatures with both excellent stereoselectivity and yield which resulted from the synergy of CCOF confinement effect and M NP catalytic activation. Notably, the needed thermal energy for the asymmetric reactions herein is derived from the photothermal conversion via porphyrin-based CCOF upon irradiation with visible light. Remarkably, the CCOF confinement effect can be effectively maintained up to 100 °C for the asymmetric one-pot Henry and A
-coupling reactions herein.
Immunosuppressive molecules are extremely valuable prognostic biomarkers across different cancer types. However, the diversity of different immunosuppressive molecules makes it very difficult to ...accurately predict clinical outcomes based only on a single immunosuppressive molecule. Here, we establish a comprehensive immune scoring system (ISS
) based on 6 immunosuppressive ligands (NECTIN2, CEACAM1, HMGB1, SIGLEC6, CD44, and CD155) using the LASSO method to improve prognostic accuracy and provide an additional selection strategy for adjuvant chemotherapy of gastric cancer (GC). The results show that ISS
is an independent prognostic factor and a supplement of TNM stage for GC patients, and it can improve their prognosis prediction accuracy; in addition, it can distinguish GC patients with better prognosis from those with high prognostic nutritional index score; furthermore, ISS
can also be used as a tool to select GC patients who would benefit from adjuvant chemotherapy independent of their TNM stages, MSI status and EBV status.
Owing to their permanent porosity, highly ordered and extended structure, good chemical stability, and tunability, covalent organic frameworks (COFs) have emerged as a new type of organic materials ...that can offer various applications in different fields. Benefiting from the huge database of organic reactions, the required functionality of COFs can be readily achieved by modification of the corresponding organic functional groups on either polymerizable monomers or established COF frameworks. This striking feature allows homochiral covalent organic frameworks (HCCOFs) to be reasonably designed and synthesized, as well as their use as a unique platform to fabricate asymmetric catalysts. This contribution provides an overview of new progress in HCCOF‐based asymmetric catalysis, including design, synthesis, and their application in asymmetric organic synthesis. Moreover, major challenges and developing trends in this field are also discussed. It is anticipated that this review article will provide some new insights into HCCOFs for heterogeneous asymmetric catalysis and help to encourage further contributions in this young but promising field.
Chirality from COFs: Owing to their permanent porosity, highly ordered and extended structure, good chemical stability, and tunability, covalent organic frameworks have emerged as a new type of organic materials that can offer various applications in different fields. Herein, the design and synthesis of chiral covalent organic frameworks and their applications in asymmetric catalysis are highlighted.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Postsynthetic modification (PSM) has been demonstrated to be a powerful method for achieving new covalent organic frameworks (COFs) via single-step or multistep organic functional group ...transformations on established COF frameworks. PSM, however, might sometimes lead to collapse of the COF framework, decreases in crystallinity, or low postsynthetic yield due to the inherent limit of solid-state synthesis. Herein we report, for the first time, a new synthetic strategy that can generate new COFs via multicomponent one-pot in situ reactions. In total, 12 α-aminonitrile- and quinoline-linked COFs with high crystallinity and permanent porosity are successfully achieved by three-component one-pot in situ Strecker and Povarov reactions under solvothermal conditions in high yields. The obtained COFs feature the same structures as those obtained from the stepwise PSM approach on an established imine-linked COF. This in situ multicomponent assembly strategy, as a synthetic methodology parallel to PSM, might open a new route for constructing COFs that is not possible under PSM conditions.
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(S)-2-(2-Chlorophenyl)-2-(6,7-dihydrothieno3,2-cpyridin-5(4H)-yl)acetonitrile ((S)-CIK) is a key intermediate in the synthesis of (S)-clopidogrel, which is one of the most saleable worldwide ...antiplatelet and antithrombotic drugs. We show herein a facile method for the direct synthesis of (S)-CIK via Strecker reaction using a homochiral covalent framework catalyst in a heterogeneous way. The asymmetric synthesis involves a photothermal-conversion-triggered, thermally driven reaction which affords (S)-CIK in 98% yield with 94% enantiomeric excess under visible-light irradiation. Furthermore, the above approach is readily extended to a gram-scale level on a fixed-bed continuous-flow model reactor. The potential utility of this strategy is highlighted by the preparation of many more other types of chiral drugs and drug intermediates in a green and facile way.
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Background. Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases. Machine learning techniques were introduced to evaluate the optimal predictive clinical model of ...NAFLD. Methods. A cross-sectional study was performed with subjects who attended a health examination at the First Affiliated Hospital, Zhejiang University. Questionnaires, laboratory tests, physical examinations, and liver ultrasonography were employed. Machine learning techniques were then implemented using the open source software Weka. The tasks included feature selection and classification. Feature selection techniques built a screening model by removing the redundant features. Classification was used to build a prediction model, which was evaluated by the F-measure. 11 state-of-the-art machine learning techniques were investigated. Results. Among the 10,508 enrolled subjects, 2,522 (24%) met the diagnostic criteria of NAFLD. By leveraging a set of statistical testing techniques, BMI, triglycerides, gamma-glutamyl transpeptidase (γGT), the serum alanine aminotransferase (ALT), and uric acid were the top 5 features contributing to NAFLD. A 10-fold cross-validation was used in the classification. According to the results, the Bayesian network model demonstrated the best performance from among the 11 different techniques. It achieved accuracy, specificity, sensitivity, and F-measure scores of up to 83%, 0.878, 0.675, and 0.655, respectively. Compared with logistic regression, the Bayesian network model improves the F-measure score by 9.17%. Conclusion. Novel machine learning techniques may have screening and predictive value for NAFLD.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Tree shrews have a close relationship to primates and have many advantages over rodents in biomedical research. However, the laek of gene manipulation methods has hindered the wider use of this ...animal. Spermatogonial stem cells （SSCs） have been successfully expanded in culture to permit sophisticated gene editing in the mouse and rat. Here, we describe a culture system for the long-term expansion of tree shrew SSCs without the loss of stem cell properties. In our study, thymus cell antigen 1 was used to enrich tree shrew SSCs. RNA-sequencing analysis revealed that the Wnt/β-catenin signaling pathway was active in undifferentiated SSCs, but was downregulated upon the initiation of SSC differentiation. Exposure of tree shrew primary SSCs to recombinant Wnt3a protein during the initial passages of culture enhanced the survival of SSCs. Use of tree shrew Sertoli cells, but not mouse embryonic fibroblasts, as feeder was found to be necessary for tree shrew SSC proliferation, leading to a robust cell expansion and long-term culture. The expanded tree shrew SSCs were transfected with enhanced green fluorescent protein （EGFP）-expressing lentiviral vectors. After transplantation into sterilized adult male tree shrew＇s testes, the EGFP-tagged SSCs were able to restore spermatogenesis and successfully generate transgenic offspring. Moreover, these SSCs were suitable for the CRISPR/Cas9-mediated gene modification. The development of a culture system to expand tree shrew SSCs in combination with a gene editing approach paves the way for precise genome manipulation using the tree shrew.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Although seemingly disparate, high-energy nuclear physics (HENP) and machine learning (ML) have begun to merge in the last few years, yielding interesting results. It is worthy to raise the profile ...of utilizing this novel mindset from ML in HENP, to help interested readers see the breadth of activities around this intersection. The aim of this mini-review is to inform the community of the current status and present an overview of the application of ML to HENP. From different aspects and using examples, we examine how scientific questions involving HENP can be answered using ML.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A new composite Au@Cu(II)-MOF catalyst has been synthesized via solution impregnation and full characterized by HRTEM, SEM-EDS, XRD, gas adsorption–desorption, XPS, and ICP analysis. It has been ...shown here that the Cu(II)-framework can be a useful platform to stabilize and support gold nanoparticles (Au NPs). The obtained Au@Cu(II)-MOF exhibits a bifunctional catalytic behavior and is able to promote selective aerobic benzyl alcohol oxidation–Knoevenagel condensation in a stepwise way.
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We herein report the fabrication of a palladium nanoparticles (Pd NPs) loaded homochiral covalent organic framework using S-(+)-2-methylpiperazine and cyanuric chloride (Pd@CCOF-MPC) (2) via a ...very facile chemical approach. The chiral COF support of 1 (CCOF-MPC) is synthesized by the combination of cyanuric chloride and S-(+)-2-methylpiperazine at 90 °C for 36 h, and the Pd NPs-loaded Pd@CCOF-MPC (2) is prepared via sequential solution impregnation and NaBH4 reduction at room temperature. 2, as a highly active reusable asymmetric heterogeneous composite catalyst, is able to effectively promote the Henry reaction and reductive Heck reaction in high yield with excellent stereoselectivity.
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