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DC circuit breakers (DCCBs) with high breaking capacity and low cost are necessary for quick fault clearance in DC networks. The assembly DC circuit breakers (ADCCBs) have a main breaking section (MBS) and a sub-breaking sections (SBS) for each line, which greatly reduce the cost. But in conventional operation, it bears high voltage for a long time when there is a main switch grounding process in any line fault action. To address this problem, a multiport assembly circuit breaker based on current injection (CI-MPACB) is proposed, which is able to generate a resonant current with increasing amplitude by controlling the duty cycle of Integrated Gate-Commutated Thyristors (IGCTs). Then the resonant current is injected into the SBS to generate current zero crossing and arc extinction. A complex frequency domain circuit analysis is performed on the MBS to describe the action logic as well as the commutation characteristics. In addition, the parameters of each component of the MBS are subject to multiple constraints and reasonable design to ensure the fault current could be cut off quickly and reliably. The cost of existing design is greatly reduced due to the design idea of resonant current injection device parameter selection. Finally, a PSCAD/EMTDC simulation confirms the opening viability of CI-MPACB and the accuracy of the parameter design. The test results show that the designed CI-MPACB can cut off DC fault lines. [ABSTRACT FROM AUTHOR]

Limited resident's participation in the stock market has become a key constraint to the capital market development. Utilizing the 2019 China Household Financial Survey (CHFS) data, our paper designs probit models to examine the peer effects of residents' stock market participation and explore the intermediary mechanisms with a multiple intermediary model. We find that: (1) Resident involvement in stock market decision-making exhibits significant peer effects. (2) Heterogeneity analysis reveals that males and rural residents display more pronounced peer effects than females and urban residents. Additionally, middle-aged residents demonstrate more potent peer effects than their younger and older counterparts, with the intensity of peer effects correlating with education levels. (3)We observe that the peer effects of market participation operate by altering economic expectations and enhancing residents' financial literacy. (4) Further investigation establishes that individuals engaging in stock market investments manifest peer effects when deciding whether to diversify their stock portfolio. This study holds reference value for analyzing the impact of social interaction on financial behaviors and regulating individuals' financial conduct. [ABSTRACT FROM AUTHOR]

Breast cancer, one of the most frequently occurring cancers worldwide, is the leading cause of cancer-related death among women. AKT1, PIK3CA, PTEN and TP53 mutations were common observed in breast cancer representing potential clinical biomarkers for cancer classification and treatment. A comprehensive knowledge of AKT1, PIK3CA, PTEN and TP53 mutations in breast cancer was still insufficient in Chinese population. In this study, the complete coding regions and exon-intron boundaries of AKT1, PIK3CA, PTEN and TP53 genes were sequenced in paired breast tumor and normal tissues from 313 Chinese breast cancer patients using microfluidic PCR-based target enrichment and next-generation sequencing technology. Total 120 somatic mutations were identified in 190 of the 313 patients (60.7%), with the mutation frequency of AKT1 as 3.2%, PIK3CA as 36.4%, PTEN as 4.8%, and TP53 as 33.9%. Among these mutations, 1 in PIK3CA (p.I69N), 3 in PTEN (p.K62X, c.635-12_636delTTAACCATGCAGAT and p.N340IfsTer4) and 5 in TP53 (p.Q136AfsTer5, p.K139_P142del, p.Y234dup, p.V274LfsTer31 and p.N310TfsTer35) were novel. Notably, PIK3CA somatic mutations were significantly associated with ER-positive or PR-positive tumors. TP53 somatic mutations were significantly associated with ER-negative, PR-negative, HER2-positive, BRCA1 mutation, Ki67 high expression and basal-like tumors. Our findings provided a comprehensive mutation profiling of AKT1, PIK3CA, PTEN and TP53 genes in Chinese breast cancer patients, which have potential implications in clinical management. [ABSTRACT FROM AUTHOR]

Background: As downstream mediators of PI3K /PTEN /AKT /mTORC1 pathway, the AKT isoforms play critical roles in tumorgenesis. Although the pleiotropic effects of AKT1 in breast cancer have been reported, the genetic and epigenetic characteristics of AKT1 promoter region in breast cancer remains to be identified. In this study we aimed to investigate the promoter mutation spectrum, methylation and gene expression pattern of AKT1 and their relationship with breast cancer. Methods: By using PCR target sequence enrichment and next-generation sequencing technology, we sequenced AKT1 promoter region in pairs of breast tumor and normal tissues from 95 unselected Chinese breast cancer patients. The methylation of the promoter region and the expression profile of AKT1 in the same cohort were detected with bisulfite next-generation sequencing and qPCR, respectively. Results: We identified 28 somatic mutations in 23 of the 95 (24.2%) breast cancer samples. And 19 of the 28 mutations were located in transcription factor (TF) binding sites. In the 23 patients with somatic mutations, no significant change of methylation or expression was found comparing with other patients. AKT1 promoter region was significantly hypo-methylated in tumor compared with matched normal tissue (P = 0.0014) in the 95 patients. The expression of AKT1 was significantly suppressed in tumor tissue (P = 0.0375). In clinicopathological factor analysis, AKT1 showed significant hypo-methylation (P = 0.0249) and suppressed expression (P = 0.0375) in HER2 negative subtype. And a trend of decrease in expression level (P = 0.0624) of AKT1 in the ER negative subtype was observed, which is significantly decreased in basal-like breast tumor (P = 0.0328). Conclusions: Hypo-methylation and suppressed expression of AKT1 was observed to be associated with breast cancer in our cohort. The methylation and expression of AKT1 were both significantly associated with HER2 status. The promoter mutation of AKT1 did not show significant association with its methylation and expression status. These results suggested that the promoter mutation, methylation and gene expression of AKT1 may play distinct roles in tumorgenesis of breast cancer and the integrated analysis of methylation and expression of AKT1 might serve as potential biomarkers for diagnosis and classification of breast cancer. [ABSTRACT FROM AUTHOR]

Background: Nontuberculous mycobacteria (NTM) have been reported to be increasing worldwide and its geographic distribution differs by region. The aim of this study was to describe the epidemiology and distribution of NTM in the eastern part of China. Methods: Sputum samples were collected from 30 surveillance sites for tuberculosis drug resistance test from May 1, 2008 to December 31, 2008. Identification was performed using a biochemical test, multiplex PCR and GenoType Mycobacterium CM/AS assay. Results: A total of 1779 smear positive clinical isolates were obtained, of which 60 (3.37%) were NTM. Five species/complex of NTM were identified; M. intracellulare was the predominated species (68.33%), followed by M. abscessus-M. immunogenum (13.33%), Mycobacterium spec. (10.00%), M. Kansasii (6.67%) and M. peregrinum-M. alvei-M. septicum (1.67%). Conclusion: M. intracellulare was the main species of NTM in the eastern part of China and clinical physicians should pay more attention to NTM induced pulmonary disease. Author Summary: Nontuberculous mycobacteria (NTM) exist ubiquitously in the environment and cause many kinds of diseases including pulmonary infection. Despite this, NTM does not match compulsory report policy in many countries, such as China. Thus, the epidemiology of NTM is generally unknown. Furthermore, misdiagnosis of nontuberculous mycobacterium disease as multi-drug resistant tuberculosis (MDR-TB) frequently occurs in clinical settings because of similar clinical manifestations. Therefore, elucidating the epidemiology and distribution of NTM species is important and may have a profound and lasting impact on the prevalence of pulmonary NTM disease. In our study, we enrolled smear-positive sputum samples during 2008 from Jiangsu province in the eastern region of China. Traditional biochemical tests and molecular biological methods were performed to distinguish NTM isolates to species/complex level. For the first time, we provide a snapshot of the epidemiology and geographic distribution of NTM in Jiangsu province. The proportion of NTM was 3.37% of all the Mycobacterium isolates and the species of NTM differed by area. [ABSTRACT FROM AUTHOR]

Objective: To evaluate a biochip system in determining isoniazid and rifampicin resistances of Mycobacterium tuberculosis in sputum samples in a Chinese population., Methods: We assembled 907 sputum smeared positive specimens of tuberculosis patients in total. Each sample would be separated into two parts for culture and biochip assay simultaneously. And those cultured positive and having full drug resistance results would be used as reference. The McNemar χ² test was adopted for evaluating the paired 2×2 table., Results: Compared with drug sensitivity test, the agreement rates of the two methods in detecting rifampicin and isoniazid resistances were 93.37% and 94.49%, respectively. The sensitivity and specificity of biochip in detecting isoniazid were 74.31% and 96.92%, respectively. Meanwhile, the sensitivity and specificity for rifampicin were 79.76% and 96.53%, respectively. For multi-drug resistance, the sensitivity and specificity were 64.62% and 97.75%, respectively., Conclusions: The biochip system is a rapid and accurate method for drug resistant tuberculosis diagnosis using sputum samples directly, especially for rifampicin resistance detection.