Symmetric Criticality for Tight Knots

We prove a version of symmetric criticality for ropelength-critical knots. Our theorem implies that a knot or link with a symmetric representative has a ropelength-critical configuration with the same symmetry. We use this to construct new examples of ropelength critical configurations for knots and links which are different from the ropelength minima for these knot and link types.Comment: This version adds references, and most importantly an acknowledgements section which should have been in the original postin

Controlling platinum, ruthenium, and osmium reactivity for anticancer drug design

The main task of the medicinal chemist is to design molecules that interact specifically with derailed or degenerating processes in a diseased organism, translating the available knowledge of pathobiochemical and physiological data into chemically useful information and structures. Current knowledge of the biological and chemical processes underlying diseases is vast and rapidly expanding. In particular the unraveling of the genome in combination with, for instance, the rapid development of structural biology has led to an explosion in available information and identification of new targets for chemotherapy. The task of translating this wealth of data into active and selective new drugs is an enormous, but realistic, challenge. It requires knowledge from many different fields, including molecular biology, chemistry, pharmacology, physiology, and medicine and as such requires a truly interdisciplinary approach. Ultimately, the goal is to design molecules that satisfy all the requirements for a candidate drug to function therapeutically. Therapeutic activity can then be achieved by an understanding of and control over structure and reactivity of the candidate drug through molecular manipulation

Synthesis and Reactivity of Boratabenzene Ruthenium and Osmium Complexes and Rh-Catalyzed C-H、C-C and C-N Bond Activation

硼杂苯（Bb,boratabenzene）是含6个电子的芳香性杂环，可作为环戊二烯基（Cp）的等电子配体，配位化学性质和Cp相似。同时，硼杂苯配体又表现出和Cp配体电子性质上的差异，Boratabenzene要比Cp配体缺电子，从而会使Bb配合物的金属中心更具亲电性，因此，这些配体与金属络合后的配合物又可表现出和相应的Cp配合物不尽相同的反应性质，在催化反应中可得到不同的催化产物。此外，还可以通过改变硼上的取代基方便地调节配体的电子性质和空间位阻，从而调控相应络合物的反应性质。 半夹心型环戊二烯基钌的配合物（如(5-C5R5)RuXL2）具有丰富的金属有机化学...Boron-containing analogs of cyclopentadienyl ligand such as boratabenzene are six-π electron aromatic borataheterocycles that is isoelectronic and isostructural with the ubiquitous Cp ligand. Their electronic characters are different from that of Cp to some extent with the boratabenzene ligand less electron-donating. Thus, the borataheterocycle, upon complexation to transition metals, can furnish ...学位：理学博士院系专业：化学化工学院_物理化学学号：2052009015335

Sources of possible artefacts in the contrast evaluation for the backscattering polarimetric images of different targets in turbid medium

International audienceIt is known that polarization-sensitive backscattering images of different objects in turbid media may show better contrasts than usual intensity images. Polarimetric image contrast depends on both target and background polarization properties and typically involves averaging over groups of pixels, corresponding to given areas of the image. By means of numerical modelling we show that the experimental arrangement, namely, the shape of turbid medium container, the optical properties of the container walls, the relative positioning of the absorbing, scattering and reflecting targets with respect to each other and to the container walls, as well as the choice of the image areas for the contrast calculations, can strongly affect the final results for both linearly and circularly polarized light

Group VIII Coordination Chemistry of a Pincer-Type Bis(8-quinolinyl)amido Ligand

This paper provides an entry point to the coordination chemistry of the group VIII chemistry of the bis(8-quinolinyl)amine (BQA) ligand. In this context, mono- and disubstituted BQA complexes of iron, ruthenium, and osmium are described. For example, the low-spin bis-ligated Fe(III) complex [Fe(BQA)2][BPh4] has been prepared via amine addition to FeCl3 in the presence of a base and NaBPh4. Complexes featuring a single BQA ligand are more readily prepared for Ru and Os. Auxiliary ligands featuring a single BQA ligand, along with two other L-type donor ligands, allow for a variety of ligand types to occupy a sixth coordination site. Representative examples include the halide and pseudohalide complexes trans-(BQA)MX(PPh3)2 (M = Ru, Os; X = Cl, Br, N3, OTf), as well as the hydride and alkyl complexes trans-(BQA)RuH(PMe3)2 and trans-(BQA)RuMe(PMe3)2. Electrochemical studies are discussed that help to contextualize the BQA ligand with respect to its neutral counterpart 2,2′,2′′-terpyridine (terpy) in terms of electron-releasing character. Bidentate ligands have been explored in conjunction with the BQA ligand. Thus, the bidentate, monoanionic aryl(8-quinolinyl)amido ligand 3,5-(CF3)2-(C6H3)QA has been installed onto the (BQA)Ru platform to provide (BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3). A bis(phosphino)borate ligand stabilizes the five-coordinate complex [Ph2B(CH2PPh2)2]Ru(BQA). Finally, access to dinitrogen complexes of the types [(BQA)Ru(N2)(PPh3)2][PF6], [(BQA)Ru(N2)(PMe3)2][PF6], and [(BQA)Os(N2)(PPh3)2][PF6] is provided by exposure of the sixth coordination site under a N2 atmosphere

Development of dielectric windows for space- craft antennas third quarterly report, 1 jan. - 31 mar. 1964

Dielectric windows for spacecraft antennas - screening tests of reinforced plastic