Donor−acceptor pair luminescence in compensated Si for solar cells

A broad band with a fine structure on the higher energy side has been commonly observed in photoluminescence at 4.2 K from compensated Si for solar cells involving P donors and B acceptors on the order of 1016 cm⁻³. We calculated the theoretical spectrum of donor−acceptor (DA) pair luminescence from the density distribution of pairs as a function of the transition energy of respective pairs with separations ranging from 1.9 to 3.3 nm. A close agreement was obtained between the observed spectral structure and the theoretical curve using the generally accepted P donor and B acceptor ionizationenergies, where a systematic deviation was explained by the Van der Waals interaction between shallow P donors and B acceptors. This allows us to conclude that the band with the fine structure is due to the P-donor−B-acceptor pair recombination. This identification was confirmed by the observation of As-donor−B-acceptor pair luminescence in an As-doped sample. The present findings indicate that P and B impurities with concentrations on the order of 1016 cm⁻³ are unlikely to form complexes and that their ionizationenergies are not changed from those in the low concentration range.This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy, Trade and Industry (METI)

Multilevel metallization based on Al CVD

科研費報告書収録論文(課題番号:08555073・基盤研究(A)(2)・H8～H10/研究代表者:坪内, 和夫/超LSI多層配線A1CVD装置の開発

Novel function of HATs and HDACs in homologous recombination through acetylation of human RAD52 at double-strand break sites

The p300 and CBP histone acetyltransferases are recruited to DNA double-strand break (DSB) sites where they induce histone acetylation, thereby influencing the chromatin structure and DNA repair process. Whether p300/CBP at DSB sites also acetylate non-histone proteins, and how their acetylation affects DSB repair, remain unknown. Here we show that p300/CBP acetylate RAD52, a human homologous recombination (HR) DNA repair protein, at DSB sites. Using in vitro acetylated RAD52, we identified 13 potential acetylation sites in RAD52 by a mass spectrometry analysis. An immunofluorescence microscopy analysis revealed that RAD52 acetylation at DSBs sites is counteracted by SIRT2- and SIRT3-mediated deacetylation, and that non-acetylated RAD52 initially accumulates at DSB sites, but dissociates prematurely from them. In the absence of RAD52 acetylation, RAD51, which plays a central role in HR, also dissociates prematurely from DSB sites, and hence HR is impaired. Furthermore, inhibition of ataxia telangiectasia mutated (ATM) protein by siRNA or inhibitor treatment demonstrated that the acetylation of RAD52 at DSB sites is dependent on the ATM protein kinase activity, through the formation of RAD52, p300/CBP, SIRT2, and SIRT3 foci at DSB sites. Our findings clarify the importance of RAD52 acetylation in HR and its underlying mechanism

ダイガク ボランティア カンレン ソシキ ニヨル ガクセイ ボランティア カツドウ ノ ジッサイ

東日本大震災から現在に至るまでのこの期間（研究期間[2016－2017年]）、この震災について大学教員が大学生にどのように語ってきたのか、また大学の教学システムは学生にどのような影響を与えてきたのか、十分に検討されてきたとは言えない状況であった。本研究では、ボランティアに関する大学教育のあり方を大学組織の立場から検討することを目的とし、震災ボランティアに学生を派遣している各大学のボランティアステーション・スタッフへの調査をもとに、その活動の実態把握を行った。結果、ボランティア関連組織を設立していた大学においては、学生にとってのボランティアの有用性が意識されており、自治体との連携や大学間連携が進みつつある現状が明らかとなったが、学内の体制整備、移動費など費用の工面、学生ボランティアの安全確保、被災地域となった場合のボランティアコーディネート能力の向上などが課題として認識されていた

Fine Structure Due to Donor-Acceptor Pair Luminescence in Compensated Si

A fine structure on the higher energy side of donor-acceptor (DA) pair luminescence at 4.2K has been analyzed in compensated Si involving P donors and B acceptors. We calculated the density distribution of DA pairs against photon energy from the number of pairs as a function of the transition energy of respective pairs. A close agreement was obtained between the density curve and the observed spectral structure using the generally accepted values of energy gap and P donor and B acceptor ionization energies. This allows us to conclude that the structure is due to discrete DA pair recombination