Search

Clustering is one of the most important data mining technologies, and K-means is the most famous and commonly used clustering algorithm. However, the performance of K-means depends heavily on the initial centers. It is very important for K-means to select how many initial centers and which data points to choose as the initial centers. Therefore, an initial centers selection method called DPCC (density peak clustering centers) is proposed. DPCC generates a selection decision graph based on density and distance, so as to highlight all density peak points in dataset. These density peak points are the initial centers provided by DPCC for K-means. Experiments show that DPCC not only provides decision support for the number of initial centers, but also improves the accuracy of K-means and reduces the running time of K-means.

Aims/Introduction: We investigated the association between impaired fasting glucose (IFG) and cardiometabolic multimorbidity (CMM) in the Chinese population. Materials and Methods: We included 119,368 participants, free of diabetes mellitus and cardiovascular disease, who participated in the health examination (2006, 2008, 2010) of the Kailuan Study. According to World Health Organization diagnostic criteria, participants were divided into normal fasting blood glucose (FBG) (<6.1 mmol/L) and IFG (FBG 6.1–6.9 mmol/L) groups. CMM was defined as having two or more cardiometabolic diseases, including myocardial infarction, stroke and diabetes mellitus. We used Cox proportional hazards models to evaluate associations between IFG and CMM. Results: During a median follow‐up period of 13.94 years, 2,432 CMM incident events occurred. After adjusting potential confounders, the hazard ratio (HR) and 95% confidence interval (CI) for CMM in the IFG group was 2.83 (95% CI 2.58–3.10) versus the normal FBG group. The HR of IFG for diabetes mellitus was 3.43 (95% CI 3.30–3.55), which was >1.25 (95% CI 1.13–1.37) for myocardial infarction, 1.16 (95% CI 1.07–1.25) for ischemic stroke and 1.06 (95% CI 0.88–1.27) for hemorrhagic stroke. Compared with normal FBG, HRs for risk of IFG for CMM were 2.73 (95% CI 2.48–3.02) in men and 3.86 (95% CI 2.92–5.09) in women. Conclusion: IFG was a risk factor for CMM. The effect of IFG on diabetes mellitus was stronger than that on other cardiometabolic diseases. The effects of IFG for CMM differed by sex. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The rhodium‐catalyzed C—H bond activation and cyclization of 3‐oxopent‐4‐enenitriles with alkynes proceed efficiently. Various 2H‐pyrans with multiple substituents are achieved in good yields through regioselective formation of C—O and C—C bonds. Transformations involving hydroxy‐alkynoates resulted in products with a furo[3,4‐b]pyran skeleton via further intramolecular ester exchange processes. Different from the traditional "1‐oxatrienes pathway", this method for the synthesis of useful 2H‐pyrans possesses certain highlights in terms of readily available substrates, stable and easily derivatized products, gentle and convenient operation process, and step and atom economy. [ABSTRACT FROM AUTHOR]

Gastric cancer (GC) is one of the most common malignant tumors in the digestive tract, and chemotherapy plays an irreplaceable role in the comprehensive treatment of GC. However, chemoresistance makes it difficult for patients with GC to benefit steadily from chemotherapy in the long term, which ultimately leads to tumor recurrence, metastasis, and patient death. Elucidating the detailed mechanism of chemoresistance in GC and identifying specific therapeutic targets will help to solve the difficult problem of chemoresistance and improve the prognosis of patients with GC. This review summarizes and clarifies the cellular and molecular mechanisms underlying chemoresistance for GC. [ABSTRACT FROM AUTHOR]

A [3+2]/[2+1] domino annulation reaction of cyclohexadienones and α‐aryl vinylsulfonium salts has been reported. A range of cyclopropane fused tricyclic enones bearing four contiguous stereocenters were obtained as a single diastereomer in 44–93% yields. The synthetic utility was demonstrated with the gram‐scale reactions and further transformations of the products. [ABSTRACT FROM AUTHOR]

The domino annulation reactions of o‐aminotrifluoroacetophenone derivatives and MBH carbonates enabled by PPh3 have been reported, which provide a series of tetrahydrofuro[3,2‐b]indolines containing a CF3‐substituted tetrasubstituted carbon stereocenters in yields of 74 to 95% and >20:1 dr. In this process, MBH carbonates were used as C1/C3 synthons. The MTT assay shows that the products exhibit the activity of inhibitory effect on proliferation on Hela cancer cell line. [ABSTRACT FROM AUTHOR]

The transmetalation triggered rhodium‐catalyzed C−H bond activation and tandem annulation of 2‐biphenylboronic acids with sulfoxonium ylides or iodonium ylides has been developed. Various products of phenanthrenes were constructed under redox‐neutral conditions in 34–86% yields. Several mechanism exploration experiments and derivatization reactions were conducted in sequence to gain a deeper understanding of the process and the potential of this transformation. It offers an alternative approach for the synthesis of phenanthrene derivatives. [ABSTRACT FROM AUTHOR]