Narrow Results

Studying the transport characteristics of carriers in quantum dot (QD) film provides theory support for the structure design and performance improvement of QD film device. However, time of flight experiment can only test the global optoelectric current signal brought by the carrier transport, and cannot analyze the carrier transport in the transport layer. Here, the hopping transport model of photogenerated carriers in QD films was established to study the expansion and drift movement of carriers in the PDE module of COMSOL. According to the material properties of the actual QD films, the carrier transport in single-size QD films was studied.

We present a method of measuring the elliptic flow (v₂) of nonphotonic electrons from heavy flavor quark decays using the STAR detector at RHIC in Au + Au collisions at . Inclusive electrons are identified in the p_T range 0.5–4 GeV/c at mid-rapidity -1 < η < 0 by the STAR time projection chamber (TPC) and time-of-flight detector. Photonic e⁺e^- pairs with characteristic low invariant mass are reconstructed in the TPC and their v₂ is measured using the standard event plane method by subtracting the combinatorial background in the dN/dΔϕ distributions in each p_T bin. The nonphotonic electron v₂ and its propagated error can be derived from the inclusive and photonic electron v₂. We estimate the necessary statistics and errors of nonphotonic electron v₂ for a more recent RHIC run.

Meso-tetraphenylporphyrinatooxidovanadium(IV) [V^IVO(TPP)] (1) and 2,3,7,8,12,13, 17,18-octabromo-meso-tetraphenylporphyrinatooxidovanadium(IV) [V^IVO(TPPBr${}_8)$] (2) were synthesized and characterized by various spectroscopic techniques. 1 and 2 were utilized as efficient catalysts for the selective epoxidation of olefins. Catalyst 2 shows very high catalytic activity (TOF = 8783–13108 h${}^{-1})$ as compared to 1 (TOF = 2175–3296 h${}^{-1})$. The catalysts are recyclable, as their recyclability was checked for four cycles and show only minor reduction of their efficiency.

The Beijing spectrometer III (BESIII) is a high precision detector located at the Beijing electron positron collider II (BEPCII). After running ten years, the BESIII sub-systems are suffering from the aging problems that lead to a performance degradation. In order to ensure the study of the important physics topics in tau-charm energy region that can be further explored at the BESIII, the BESIII experiment has received several upgrades. We report the upgrades of the BESIII, including the inner part of the drift chamber, the end cap of the time-of-flight system and the valve box of the superconducting magnet.