A new reaction path for the C + NO reaction: dynamics on the 4A' potential-energy surface

We present a new reaction path without significant barriers for the C + NO reaction, forming ground state N((4)S) and CO. Electronic structure (CASPT2) calculations have been performed for the two lowest (4)A' states of the CNO system. The lowest of these states shows no significant barriers against reaction in the C + NO or O + CN channels. This surface has been fitted to an analytical function using a many-body expansion. Using this surface, and the previously published (2)A' and (2)A' surfaces [Andersson et al., Phys. Chem. Chem. Phys., 2000, 2, 613; Andersson et al., Chem. Phys., 2000, 259, 99], we have performed quasiclassical trajectory (QCT) calculations, obtaining rate coefficients for the C((3)P) + NO(X(2)Pi) --> CO(X(1)Sigma(+)) + N((4)S,(2)D) and C((3)P) + NO(X(2)Pi) --> O((3)P) + CN(X(2)Sigma(+)) reactions. We have also simulated the crossed molecular beam experiments of Naulin et al. [Chem. Phys., 1991, 153, 519] The inclusion of the (4)A' surface in the QCT calculations gives excellent agreement with experiments. This is the first time an adiabatic pathway from C((3)P) + NO(X(2)Pi) to CO(X(1)Sigma(+))+N((4)S) has been reported.     

Reaction of α-bromocarboxylic acids with hydrazine and dimethylhydrazine

Nucleofilic reaction of a series of α-bromocarboxylic acids with hydrazine and dimethylhydrazine is studied. High reactivity of α-bromocarboxylic acids is revealed and a series of α-hydrazinoarboxylic acids and N-(1-carboxyalkyl)-N,N-dimethylhydrazinium bromides are synthesized.     

Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands

The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane ( 1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane ( 2). A homoleptic ([Ru( 2) 2] (2+)) and a heteroleptic complex ([Ru(ttpy)( 2)] (2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru( 1) 2] (2+). The excited-state lifetime of the homoleptic Ru (II) complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru (II) complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru (II) ion less octahedral in [Ru( 2) 2] (2+) than in [Ru( 1) 2] (2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ( (3)MLCT) and metal-centered ( (3)MC) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru (II) complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (3)MLCT states to short-lived (3)MC states.     

A unique equilibrium efficient frontier with fixed-sum outputs in data envelopment analysis

Based on the equilibrium efficient frontier data envelopment analysis (EEFDEA) approach, Fang (J Oper Res Soc 67:412–420, 2015a) developed an equivalent linear programming model to improve and strengthen the EEFDEA approach. Furthermore, Fang (2015a) indicated that his secondary goal approach can achieve a unique equilibrium efficient frontier. However, through a simple counterexample we demonstrate that Fang’s secondary goal approach cannot always achieve uniqueness of the equilibrium efficient frontier. In this paper, we propose an algorithm based on the secondary goal approach to address the problem. The proposed algorithm is proven mathematically to be an effective approach to guaranteeing the uniqueness of the equilibrium efficient frontier.     

细胞显微光谱研究竹红菌甲素在癌细胞内的滞留效应

利用细胞显微光谱技术,在20000～12000cm-1范围内测量了经过浓度为20μg*mL-1竹红菌甲素(HA)培养23个小时的小鼠淋巴癌细胞和未经HA培养的小鼠淋巴癌细胞的光谱.结果显示两者有明显的差异,说明HA使癌细胞发生了改变;在经HA培养的细胞光谱中还检测到HA的荧光峰,提示HA在癌细胞中滞留.发展了利用显微光谱研究细胞在药物作用下的变化这一技术.     

Synthesis and Electrochemical Properties of Highly Crystallized CuV2O6 Nanowires

CuV₂O₆ nanowires were prepared via a simple hydrothermal route using NH₄VO₃ and Cu(NO₃)₂ as starting materials. The structures and electrochemical properties of CuV₂O₆ nanowires were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that the CuV₂O₆ nanowires are about 100 nm in width and single crystalline grown along [001] direction. CuV₂O₆ nanowires delivered a high initial discharge capacity of 435 and 351 mA·h/g at current densities of 50 and 100 mA·h/g, respectively. The electrochemical kinetics of the CuV₂O₆ nanowires was also investigated by means of electrochemical impedance spectroscopy(EIS) and the poor rate performance was observed, which may be attributed to the low ion diffusion coefficient of the CuV₂O₆ nanowires.     

Synthesis of a Thymidine Dimer Containing a Tetrazole‐2,5‐diyl Internucleosidic Linkage and Its Insertion into Oligodeoxynucleotides

Thymidine dimers in which the natural phosphodiester linkage has been replaced by a 2,5‐disubstituted tetrazole ring are synthesized and incorporated into oligodeoxynucleotides (ODNs). The synthesis is accomplished by two strategies based on an alkylation of 5′‐O‐trityl‐on and 5′‐O‐trityl‐off 3′‐deoxy‐3′‐(1H‐tetrazol‐5‐yl)thymidines with 5′‐iodo‐5′‐deoxythymidine in the presence of Et₃N, and the formation of only 2‐substituted tetrazol‐5‐yl linkages is observed in 89 and 46% yields, respectively. The nucleoside dimer formed is reacted with 4,4′‐dimethoxytrityl chloride (DMTCl), followed by treatment with 2‐cyanoethyl tetraisopropylphosphordiamidite in the presence of N,N‐diisopropylammonium tetrazolide, to afford the 5′‐O‐DMT‐protected dinucleoside phosphoramidite that is used for incorporation into ODNs on an automated DNA synthesizer. The modified ODNs with one and up to five tetrazole internucleosidic linkages are obtained in good yields. The thermal stability of DNA/DNA and DNA/RNA duplexes is studied by UV experiments and reported also.     

Empowering the configuration-IP: new PTAS results for scheduling with setup times

Mathematical Programming - Integer linear programs of configurations, or configuration IPs, are a classical tool in the design of algorithms for scheduling and packing problems where a set of items...     

Forming the GaN Nanocrystals on the Graphene-Like g-AlN and g-Si3N3 Surface

Physics of the Solid State - The formation of GaN nanocrystals on the graphene-like AlN (g-AlN) modification and graphene-like (g-Si3N3) silicon nitride by ammonia molecular beam epitaxy has been...