Packing two disks into a polygonal environment

We consider the following problem. Given a polygon P, possibly with holes, and having n vertices, compute a pair of equal radius disks that do not intersect each other, are contained in P, and whose radius is maximized. Our main result is a simple randomized algorithm whose expected running time, on any input, is O(nlogn). This is optimal in the algebraic decision tree model of computation.     

Synthèse d'hétérocycles en catalyse par transfert de phase

A general study of the chemical behavior of heterocyclic anions, dianions and dianionic reagents under phase transfer catalysis conditions allowed us to synthesize various heterocyclic compounds such as imidazo[2,1-b]thiazole and derivatives; imidazo[2,1-b]thiazine and imidazo[2,1-b]benzothiazepine. Reaction conditions e.g., catalyst, solvent, temperature, etc., are indicated.     

Preparation d'alkyl-4 γ-lactones insaturee optiquement pures. Application a la synthese de la (+) tetrahydrocerulenine.

Optically pure enantiomers of unsaturated 4-alkyl γ-lactones are synthesized from optically active propargylic carbinols obtained by asymmetric reduction of α-acetylenic ketones with the complex [LiAlH₄,N-methylephedrine,3-5 dimethylphenol]. (+) Tetrahydrocerulenin is prepared from the butenolide 6 obtained by this way.     

重氮树脂-聚(4-羧酸苯基)乙炔自组装膜与光电转换

近年来 ,自组装及其形成的多层复合膜已经在导电、生物传感器及非线性光学等领域得到深入研究 ,特别是以聚阴离子与聚阳离子相互作用的静电自组装研究更为深入 .这一技术制备方法简单 ,无需特别的设备 ,对膜层厚度能随意调控 ,并以水作为介质 ,对环境无害 [1～ 3] .共轭高分子 (如聚苯胺、聚吡咯及聚苯亚乙烯等 )通过自组装形成共轭高分子膜 ,对制备具有导电、光电和传输等功能的薄膜半导体器件具有重要意义 .聚乙炔类是最早被发现且理论与应用研究最多的一类共轭高分子材料[4 ,5] .本文以聚 ( 4 -羧酸苯基 )乙炔 ( PCPA)为聚阴离子 ,以重…     

Steric Effects on Reaction Rates. Rate and equilibrium constants for oxidation of cyclanols

Equilibrium constants for oxidations of cyclanols by cyclohexanone in benzene have been determined in the presence of aluminium isopropoxide. The free energies of the equilibrium (ΔG_ox) are correlated with equilibrium constants for dissociation of cyanohydrins, rate constants for cyclanol oxidation with chromic acid, ketone reduction with sodium borohydride and trifluoroethanolysis of tosylates.     

Structural and process controls of AIEgens for NIR-II theranostics

Aggregation-induced emission (AIE) is a cutting-edge fluorescence technology, giving highly-efficient solid-state photoluminescence. Particularly, AIE luminogens (AIEgens) with emission in the range of second near-infrared window (NIR-II, 1000–1700 nm) have displayed salient advantages for biomedical imaging and therapy. However, the molecular design strategy and underlying mechanism for regulating the balance between fluorescence (radiative pathway) and photothermal effect (non-radiative pathway) in these narrow bandgap materials remain obscure. In this review, we outline the latest achievements in the molecular guidelines and photophysical process control for developing highly efficient NIR-II emitters or photothermal agents with aggregation-induced emission (AIE) attributes. We provide insights to optimize fluorescence efficiency by regulating multi-hierarchical structures from single molecules (flexibilization) to molecular aggregates (rigidification). We also discuss the crucial role of intramolecular motions in molecular aggregates for balancing the functions of fluorescence imaging and photothermal therapy. The superiority of the NIR-II region is demonstrated by fluorescence/photoacoustic imaging of blood vessels and the brain as well as photothermal ablation of the tumor. Finally, a summary of the challenges and perspectives of NIR-II AIEgens for in vivo theranostics is given.

Structural and process controls of NIR-II AIEgens realize manipulating of radiative (R) and nonradiative (NR) decay for precise theranostics.