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The ability of cells to repair DNA double-strand breaks (DSBs) is important for maintaining genome stability and eliminating oncogenic DNA lesions. Two distinct and complementary pathways, non-homologous end joining (NHEJ) and homologous recombination (HR), are employed by mammalian cells to repair DNA DSBs. Each pathway is tightly controlled in response to increased DSBs. The Ku heterodimer has been shown to play a regulatory role in NHEJ repair. Ku80 ubiquitination contributes to the selection of a DSB repair pathway by causing the removal of Ku heterodimers from DSB sites. However, whether Ku80 deubiquitination also plays a role in regulating DSB repair is unknown. To address this question, we performed a comprehensive study of the deubiquitinase specific for Ku80, and our study showed that the deubiquitinase OTUD5 serves as an important regulator of NHEJ repair by increasing the stability of Ku80. Further studies revealed that OTUD5 depletion impaired NHEJ repair, and hence reduced overall DSB repair. Furthermore, OTUD5-depleted cells displayed excess end resection; as a result, HR repair was facilitated by OTUD5 depletion during the S/G2 phase. In summary, our study demonstrates that OTUD5 is a specific deubiquitinase for Ku80 and establishes OTUD5 as an important and positive regulator of NHEJ repair. [ABSTRACT FROM AUTHOR]

In this study, a new Al–17Si–2.5P master alloy has been successfully prepared to refine primary Si in hypereutectic A390 alloys. By means of electron probe microanalyzer (EPMA), a large number of AlP particles can be found in the Al–17Si–2.5P master alloy. An orthogonal L9(33) test was designed to investigate the integrated effects of refining factors including phosphorus addition level, melting temperature and holding time, and subsequently to optimize the processing parameters. It is found that under the optimized conditions, i.e., phosphorus addition of 375 ppm, melting temperature of 800 °C, and holding time of 30 min, the average sizes of primary Si can be most remarkably decreased from 116 μm to 14 μm with sphere-like morphology. Meanwhile, the Brinell hardness and tensile strength can be significantly increased by 14.1 and 27.8%, respectively. In addition, thermal analysis is also performed with differential scanning calorimeter (DSC) to analyze the solidification process of Al–18Si alloys. [ABSTRACT FROM AUTHOR]

A novel method of atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS) for the analysis of organochlorine pesticides (OCPs) in human serum was developed. Better sensitivity and selectivity were achieved compared to conventional gas chromatography-mass spectrometry (GC-MS) and GC-MS/MS. The limits of detection (LODs) of OCPs ranged from 0.22 to 0.90 pg/mL for the analysis in serum samples. The recoveries and repeatability of the developed method were evaluated from the analysis of spiked serum at three levels (0.05, 0.5, and 5 ng/mL). The recoveries ranged from 84.5 to 118.2%, and the relative standard deviations (RSDs) were less than 20%. The developed APGC-MS/MS method was applied to measure OCPs in pooled human serum from the interlaboratory comparison study. The obtained results of OCPs were within the acceptable ranges. The method has been successfully applied to the analysis of OCPs in human serum samples with the sample volume of up to 100 μL. [ABSTRACT FROM AUTHOR]

We report a trap-assisted photomultiplication (PM) phenomenon in solution-processed polymer photodetectors (PPDs) based on P3HT:PC71BM as the active layer, the maximum EQE of 16,700% is obtained for the PPDs with PC71BM doping weight ratio of 1%. The PM phenomenon is attributed to the enhanced hole tunneling injection assisted by trapped electrons in PC71BM near Al cathode, which can be demonstrated by the transient photocurrent curves and EQE spectra of PPDs with different PC71BM doping ratios. The positive effect of trapped electrons in PC71BM near Al cathode on the hole tunneling injection is further confirmed by the simulated optical field and exciton generation rate distributions in the active layer and the EQE spectra of PPDs with Al(1)/P3HT:PC71BM(100:1)/Al(2) device structure under forward and reverse biases. This discovery may open a new road for organic materials to be used in highly sensitive photodetectors while preserving the advantages of organic materials. [ABSTRACT FROM AUTHOR]