RF transport

This paper deals with the techniques of transport of high-power radiofrequency (RF) power from a RF power source to the cavities of an accelerator. Since the theory of electromagnetic waves in waveguides and of waveguide components is very well explained in a number of excellent text books it will limit itself on special waveguide distributions and on a number of, although not complete list of, special problems which sometimes occur in RF power transportation systems.Comment: 8 pages, contribution to the CAS - CERN Accelerator School: Course on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai

Związki koordynacyjne wybranych jonów metali przejściowych z ligandami triiminowymi : synteza, struktura, właściwości fotoluminescencyjne i magnetyczne oraz aktywność katalityczna i biologiczna

2,2′:6′,2″-Terpyridine and its analogs are widely used building blocks in coordination chemistry used to obtain stable transition metal complexes with important properties for potential applications. The ease of structural modification of these ligands, due to the development of a one-step Kröhnke synthesis, allows for systematic studies of the influence of the ligand structure on the properties of the coordination compound. This work presents research on a group of coordination compounds of selected transition metals: platinum(II), gold(III), copper(II), cobalt(II) and rhenium(II) with derivatives of 2,2′:6′,2″-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine. The obtained compounds were subjected to structural analysis and experiments determining their properties in biological, catalytic, luminescent and magnetic activity. In the group of gold(III), platinum(II), and copper(II) complexes with biological activity, it was found that the introduction of a substituent into the trimimine ligand leads to an increase in the cytotoxicity of the compounds and the substituents displaying a small dihedral angle between the plane of the substituent and the plane of the central pyridine of the ligand’s core favored the planar structure of the complex ion [MCl(N N N-κ³N)]n+ and increased their ability to interact with the DNA of cells. Research on the mechanism of cell death showed that the obtained compounds induced oxidative stress due to the production of reactive oxygen species, causing cell apoptosis. A prticularly strong influence of the change in ligand’s core on biological and catalytic properties was confirmed in the case of copper(II) complexes. Cu(II) compounds with 2,6-di(thiazol-2-yl)pyridine ligands were much better catalysts for the oxidation of alkanes or alcohols with the participation of “green” oxidants in comparison to their terpyridine analogues, and their mechanism of catalyzing the reaction was based on generating the hydroxyl radical HO•. On the other hand, Cu(II) coordination compounds with 2,2′:6′,2″-terpyridine ligands, as a rule, showed higher cytotoxic activity. For carbonyl rhenium(I) compounds, studies of the emission properties and photodynamics of excited states showed that the introduction of strong electron-donating substituents attached to the ligand core leads to a significant increase in the lifetime of excited states and bigger potential of these compounds as an active layer in OLEDs. Low-temperature studies of magnetic susceptibility in a constant and alternating magnetic current confirmed that the obtained cobalt(II) coordination compounds have the single-ion magnets (SIM) properties and their spin-lattice slow magnetic relaxation occurs via various mechanisms. The correlation of the structural tests with the results of biological, catalytic, spectroscopic and magnetic experiments for all groups of compounds allowed for the determination of structure-property relationships, important for future design of coordination compounds and improving of desired physicochemical parameters

Square planar Au(III), Pt(II) and Cu(II) complexes with quinoline-substituted 2,2′:6′,2″-terpyridine ligands: From in vitro to in vivo biological properties

This work was supported by the Applied Molecular Biosciences Unit - UCIBIO which is financed by national funds from FCT (UIDP/04378/2020, UIDB/04378/2020 and fellowships SFRH/BPD/124612/2016 (C. Roma-Rodrigues), and PTDC/CVT-EPI/6685/2014 (L R. Raposo)).Cancer is the second leading cause of death worldwide. Cisplatin has challenged cancer treatment; however, resistance and side effects hamper its use. New agents displaying improved activity and more reduced side effects relative to cisplatin are needed. In this work we present the synthesis, characterization and biological activities of three complexes with quinoline-substituted 2,2′:6′,2″-terpyridine ligand: [Pt(4′-(2-quin)-terpy)Cl](SO3CF3) (1), [Au(4′-(2-quin)-terpy)Cl](PF6)2·CH3CN (2) and [Cu(4′-(2-quin)-terpy)Cl](PF6) (3). The three complexes displayed a high antiproliferative activity in ovarian carcinoma cell line (A2780) and even more noticeable in a colorectal carcinoma cell line (HCT116) following the order 3 > 2 > 1. The complexes IC50 are at least 20 × lower than the IC50 displayed by cisplatin (15.4 μM) in HCT116 cell line while displaying at the same time, much reduced cytotoxicity in a normal dermal fibroblast culture. These cytotoxic activities seem to be correlated with the inclination angles of 2-quin unit to the central pyridine. Interestingly, all complexes can interact with calf-thymus DNA (CT-DNA) in vitro via different mechanisms, although intercalation seems to be the preferred mechanism at least for 2 and 3 at higher concentrations of DNA. Moreover, circular dichroism (CD) data seems to indicate that complex 3, more planar, induces a high destabilization of the DNA double helix (shift from B-form to Z-form). Higher the deviation from planar, the lower the cytotoxicity displayed by the complexes. Cellular uptake may be also responsible for the different cytotoxicity exhibited by complexes with 3 > 2 >1. Complex 2 seems to enter cells more passively while complex 1 and 3 might enter cells via energy-dependent and -independent mechanisms. Complexes 1–3 were shown to induce ROS are associated with the increased apoptosis and autophagy. Moreover, all complexes dissipate the mitochondrial membrane potential leading to an increased BAX/BCL-2 ratio that triggered apoptosis. Complexes 2 and 3 were also shown to exhibit an anti-angiogenic effect by significantly reduce the number of newly formed blood vessel in a CAM model with no toxicity in this in vivo model. Our results seem to suggest that the increased cytotoxicity of complex 3 in HCT116 cells and its potential interest for further translation to pre-clinical mice xenografts might be associated with: 1) higher % of internalization of HCT116 cells via energy-dependent and -independent mechanisms; 2) ability to intercalate DNA and due to its planarity induced higher destabilization of DNA; 3) induce intracellular ROS that trigger apoptosis and autophagy; 4) low toxicity in an in vivo model of CAM; 5) potential anti-angiogenic effect.publishersversionpublishe

Ground- and excited-state properties of Re(I) carbonyl complexes - effect of triimine ligand core and appended heteroaromatic groups

In this work, a series of six rhenium(I) complexes bearing 2,2′ :6′ ,2′′ -terpyridine (terpy), 2,6-di(thiazol-2-yl)pyridine (dtpy), and 2,6-di(pyrazin-2-yl)pyridine (dppy) with appended quinolin-2-yl and N-ethylcarbazol-3-yl groups were prepared and spectroscopically investigated to evaluate the photophysical consequences of both the trisheterocyclic core (terpy, dtpy and dppy) and the heterocyclic substituent. The [ReCl(CO)3(Ln-κ2N)] complexes are regarded as ideal candidates for getting structure–property relationships, while terpy-like framework represents an excellent structural backbone for structural modifications. The replacement of the peripheral pyridine rings of 2,2′ :6′ ,2′′ -terpyridine by thiazoles and pyrazines resulted in a significant red-shift of the absorption and emission of [ReCl(CO)3(Ln-κ2N)] due to stabilization of the ligand-centred LUMO orbital. Both quinoline and Nethylcarbazole are extended π-conjugation organic chromophores, but they differ in electron-donating abilities. The low-energy absorption band of Re(I) complexes with the triimine ligands bearing quinolin-2-yl group was contributed by the metal-to-ligand charge-transfer (MLCT) electronic transitions. The introduction of electrondonating N-ethylcarbazol-3-yl substituent into the triimine acceptor core resulted in the change of the character of the HOMO of Re(I) complexes and a significant increase of molar absorption coefficients of the longwavelength absorption, which was assigned to a combination of 1MLCT and 1ILCT (intraligand chargetransfer) transitions. Regardless of the appended heteroaromatic group, the emitting excited state of Re(I) terpy-based complexes was demonstrated to have predominant 3MLCT character, as evidenced by comprehensive studies including static and time-resolved emission spectroscopy along with ultrafast transient absorption measurements. The diodes with Re(I) complexes dispersed molecularly in a PVK:PBD matrix were emissive andeffects of the complex structure on colour of emitted light and its intensity was pronounced

First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]

Vanadium(IV) complexes with methyl-substituted 8-hydroxyquinolines : catalytic potential in the oxidation of hydrocarbons and alcohols with peroxides and biological activity

Methyl-substituted 8-hydroxyquinolines (Hquin) were successfully used to synthetize five-coordinated oxovanadium(IV) complexes: [VO(2,6-(Me)2-quin)2] (1), [VO(2,5-(Me)2-quin)2] (2) and [VO(2-Me-quin)2] (3). Complexes 1–3 demonstrated high catalytic activity in the oxidation of hydrocarbons with H2O2 in acetonitrile at 50 C, in the presence of 2-pyrazinecarboxylic acid (PCA) as a cocatalyst. The maximum yield of cyclohexane oxidation products attained was 48%, which is high in the case of the oxidation of saturated hydrocarbons. The reaction leads to the formation of a mixture of cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone. When triphenylphosphine is added, cyclohexyl hydroperoxide is completely converted to cyclohexanol. Consideration of the regioand bond-selectivity in the oxidation of n-heptane and methylcyclohexane, respectively, indicates that the oxidation proceeds with the participation of free hydroxyl radicals. The complexes show moderate activity in the oxidation of alcohols. Complexes 1 and 2 reduce the viability of colorectal (HCT116) and ovarian (A2780) carcinoma cell lines and of normal dermal fibroblasts without showing a specific selectivity for cancer cell lines. Complex 3 on the other hand, shows a higher cytotoxicity in a colorectal carcinoma cell line (HCT116), a lower cytotoxicity towards normal dermal fibroblasts and no effect in an ovarian carcinoma cell line (order of magnitude HCT116 > fibroblasts > A2780)