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1. chinaXiv:201609.00947 [pdf]

Measurement of the fluorescence quantum yield of bis-MSB

DING Xue-Feng; WEN Liang-Jian; ZHOU Xiang; DING Ya-Yun YE Xing-Chen; ZHOU Li2 LIU Meng-Chao; CAI Hao; CAO Jun
Subjects: Physics >> Nuclear Physics

The fluorescence quantum yield of bis-MSB, a widely used liquid scintillator wavelength shifter, was measured to study the photon absorption and re-emission processes in liquid scintillator. The re-emission process affects the photoelectron yield and distribution, especially in a large liquid scintillator detector, thus must be understood to optimize the liquid scintillator for good energy resolution and to precisely simulate the detector with Monte Carlo. In this study, solutions of different bis-MSB concentration were prepared for absorption and fluorescence emission measurements to cover a broad range of wavelengths. Harmane was used as a standard reference to obtain the absolution fluorescence quantum yield. For the first time we measured the fluorescence quantum yield of bis-MSB up to 430 nm as inputs required by Monte Carlo simulation, which is 0.926±0.053 at?λex?= 350 nm.

submitted time 2016-09-13 Hits1071Downloads594 Comment 0

2. chinaXiv:201609.00946 [pdf]

Preliminary study of light yield dependence on LAB liquid scintillator composition

YE Xing-Chen; YU Bo-Xiang; ZHOU Xiang; ZHAO Li; DING Ya-Yun; LIU Meng-Chao; DING Xue-Feng; ZHANG Xuan; JIE Quan-Lin; ZHOU Li; FANG Jian; CHEN Hai-Tao; HU Wei; NIU Shun-Li; YAN Jia-Qing; ZHAO Hang; HONG Dao-Jin
Subjects: Physics >> Nuclear Physics

Liquid scintillator (LS) will be adopted as the detector material in JUNO (Jiangmen Underground Neutrino Observatory). The energy resolution requirement of JUNO is 3%, which has never previously been reached. To achieve this energy resolution, the light yield of liquid scintillator is an important factor. PPO (the fluor) and bis-MSB (the wavelength shifter) are the two main materials dissolved in LAB. To study the influence of these two materials on the transmission of scintillation photons in LS, 25 and 12 cm-long quartz vessels were used in a light yield experiment. LS samples with different concentration of PPO and bis-MSB were tested. At these lengths, the light yield growth is not obvious when the concentration of PPO is higher than 4 g/L. The influence from bis-MSB becomes insignificant when its concentration is higher than 8 mg/L. This result could provide some useful suggestions for the JUNO LS.

submitted time 2016-09-13 Hits1506Downloads827 Comment 0

3. chinaXiv:201605.01469 [pdf]

Dynamic Phosphorylation of CENP-A at Ser68 Orchestrates Its Cell-Cycle-Dependent Deposition at Centromeres

Yu, Zhouliang; Zhou, Xiang; Wang, Wenjing; Deng, Wenqiang; Fang, Junnan; Hu, Hao; Wang, Zichen; Cui, Lei; Shen, Jing; Ou, Guangshuo; Yang, Na; Chen, Ping; Xu, Rui-Ming; Li, Guohong; Yu, Zhouliang; Deng, Wenqiang; Fang, Junnan; Hu, Hao; Peng, Shengyi; Li, Shangze
Subjects: Biology >> Biophysics >> Cell Biology

The H3 histone variant CENP-A is an epigenetic marker critical for the centromere identity and function. However, the precise regulation of the spatiotemporal deposition and propagation of CENP-A at centromeres during the cell cycle is still poorly understood. Here, we show that CENP-A is phosphorylated at Ser68 during early mitosis by Cdk1. Our results demonstrate that phosphorylation of Ser68 eliminates the binding of CENP-A to the assembly factor HJURP, thus preventing the premature loading of CENP-A to the centromere prior to mitotic exit. Because Cdk1 activity is at its minimum at the mitotic exit, the ratio of Cdk1/PP1 alpha activity changes in favor of Ser68 dephosphorylation, thus making CENP-A available for centromeric deposition by HJURP. Thus, we reveal that dynamic phosphorylation of CENP-A Ser68 orchestrates the spatiotemporal assembly of newly synthesized CENP-A at active centromeres during the cell cycle.

submitted time 2016-05-12 Hits2512Downloads1451 Comment 0

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