Calibration and thermal test results of prototype bolometer sensors for ITER fusion reactor.

For over 10 years, several bolometer sensors with different properties have been tested in the IBOVAC facility. The aim has been to develop a bolometer sensor that can be operated in ITER and can withstand harsh operating conditions. For this purpose, important physical properties of the sensors, i.e., cooling time constant τ, normalized heat capacity κ, and normalized sensitivity sn, have been characterized in a vacuum condition and at various temperatures up to 300 °C. The calibration is achieved by ohmic heating of the sensor absorbers by applying a DC voltage and recording exponential current fall during heating. Recently, a Python program was developed to analyze the data and extract the above mentioned parameters including the uncertainties from recorded currents. In the present series of experiments, the latest prototype sensors developed for ITER are tested and evaluated. These include three different sensor types: two with Au absorbers on ZrO2 membranes (self-supporting substrate sensors) and one with Au absorbers on Si3N4 membranes supported by a Si frame (supported membrane sensors). Tests revealed that the sensor with ZrO2 substrate can only be operated up to 150 °C, while the supported membrane sensors passed the tests up to 300 °C successfully. These results will be used, together with other upcoming tests, such as irradiation testing, to select the most suitable sensors to be employed in ITER.

Covalent Template-Directed Synthesis of a Spoked 18-Porphyrin Nanoring.

Rings of porphyrins mimic natural light-harvesting chlorophyll arrays and offer insights into electronic delocalization, providing a motivation for creating larger nanorings with closely spaced porphyrin units. Here, we demonstrate the first synthesis of a macrocycle consisting entirely of 5,15-linked porphyrins. This porphyrin octadecamer was constructed using a covalent six-armed template, made by cobalt-catalyzed cyclotrimerization of an H-shaped tolan with porphyrin trimer ends. The porphyrins around the circumference of the nanoring were linked together by intramolecular oxidative meso-meso coupling and partial ß-ß fusion, to give a nanoring consisting of six edge-fused zinc(II) porphyrin dimer units and six un-fused nickel(II) porphyrins. STM imaging on a gold surface confirms the size and shape of the spoked 18-porphyrin nanoring (calculated diameter: 4.7 nm).

An Open-Shell Coronoid with Hybrid Chichibabin-Schlenk Conjugation.

A hexaradicaloid molecule with alternating Kekulé and non-Kekulé connectivities between adjacent spin centers was obtained by fusing two conjugation motifs in Chichibabin and Schlenk hydrocarbons into a coronoid structure. 1 H NMR, ESR, and SQUID experiments and computational analyses show that the system has a singlet ground state with a significant hexaradicaloid character (γ0 =0.826, γ1 =γ2 =0.773). It has multiple thermally accessible high-spin states (up to the septet), with uniform energy gaps of ca 1.0 kcal mol-1 between consecutive multiplicities. In line with its open-shell character, the coronoid has a small electronic band gap (ca. 0.8 eV) and undergoes two consecutive one-electron oxidations at low potentials, yielding cationic forms with extended near-infrared absorption. The hexaradicaloid, which combines open-shell and macrocyclic contributions to its π conjugation, is an example of a design strategy for multistate spin switches and redox-amphoteric NIR dyes.

Nanopatterns of arylene-alkynylene squares on graphite: self-sorting and intercalation.

Supramolecular nanopatterns of arylene-alkynylene squares with side chains of different lengths are investigated by scanning tunneling microscopy at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Self-sorting leads to the intermolecular interdigitation of alkoxy side chains of identical length. Voids inside and between the squares are occupied by intercalated solvent molecules, which numbers depend on the sizes and shapes of the nanopores. In addition, planar and non-planar coronoid polycyclic aromatic hydrocarbons (i.e., butyloxy-substituted kekulene and octulene derivatives) are found to be able to intercalate into the intramolecular nanopores.

5,10-Dimesityldiindeno[1,2-a:2',1'-i]phenanthrene: a stable biradicaloid derived from Chichibabin's hydrocarbon.

A diindenophenanthrene biradicaloid, formally derived from Chichibabin's hydrocarbon, is obtained in a short, scalable synthesis. The present system is electron-rich and devoid of conjugated substituents, and still exhibits very good stability under ambient conditions. The introduction of the diindeno[1,2-a:2',1'-i] phenanthrene ring framework results in a singlet biradicaloid system with an easily accessible triplet state (ΔE S-T = -1.30 kcal mol-1) and a small electronic bandgap (1.39 V). The stability limits of the title hydrocarbon were explored systematically in the solid state, to reveal an unusual thermally initiated hydrogen-scrambling oligomerization process.

Bowls, Hoops, and Saddles: Synthetic Approaches to Curved Aromatic Molecules.

This review summarizes recent advances in the chemistry of curved aromatic molecules. By focusing on the key accomplishments of the last decade, we provide a general overview of synthetic methods capable of efficient induction of internal strain in π-conjugated frameworks. The review is structured according to the topology change involved in the strain-inducing reaction step (cyclizations, eliminations, ring expansions and contractions), and highlights the striking diversity of structures achievable with modern synthetic methodology.

Fully Conjugated [4]Chrysaorene. Redox-Coupled Anion Binding in a Tetraradicaloid Macrocycle.

[4]Chrysaorene, a fully conjugated carbocyclic coronoid, is shown to be a low-bandgap π-conjugated system with a distinct open-shell character. The system shows good chemical stability and can be oxidized to well-defined radical cation and dication states. The cavity of [4]chrysaorene acts as an anion receptor toward halide ions with a particular selectivity toward iodides ( Ka = 207 ± 6 M-1). The interplay between anion binding and redox chemistry is demonstrated using a 1H NMR analysis in solution. In particular, a well-resolved, paramagnetically shifted spectrum of the [4]chrysaorene radical cation is observed, providing evidence for the inner binding of the iodide. The radical cation-iodide adduct can be generated in thin solid films of [4] chrysaorene by simple exposure to diiodine vapor.

Ethynylene-linked Figure-Eight Octaphyrin(1.2.1.1.1.2.1.1): Synthesis and Characterization of Its Two Oxidation States.

An octaphyrin(1.2.1.1.1.2.1.1) containing two conjugated ethynylene bridges has been synthesized and characterized. The macrocycle reveals complex conformational dynamics dependent on its protonation and oxidation state. The [40]annulenoid macrocycle and its [38]annulenoid oxidized form display residual macrocyclic ring currents. In spite of its low apparent aromaticity the new octaphyrin is a potent chromophore with a vis-NIR absorption profile strongly influenced by the redox and acid-base chemistry.

Protonation Dependent Topological Dichotomy of Core Modified Hexaphyrins: Synthesis, Characterization, and Excited State Dynamics.

Two hitherto unknown core modified hexaphyrin analogues have been synthesized and characterized where the conformational dynamics of these macrocycles in the free base form is achieved by the rotation of thienothiophene units. Further unique property of these macrocycles is the Hückel-Möbius topological switching. The thermodynamic equilibrium and kinetics of the interconversion leading to Hückel-Möbius switches have been triggered by external stimuli, such as protonation and/or temperature. We have provided a thorough solution-state spectroscopic characterization, solid-state structural evidence combined with in-depth theoretical calculations to investigate the crucial factors involved in such interconversion between Hückel and Möbius topologies for these hexaphyrins which will be useful in designing future new members to expanded porphyrin chemistry.

Octulene: A Hyperbolic Molecular Belt that Binds Chloride Anions.

Octulene, the higher homologue of kekulene and septulene, was synthesized using the fold-in method. This new hydrocarbon macrocycle contains a large 24-membered inner circuit, which is peripherally fused to 24 benzene rings. Such an arrangement produces considerable hyperbolic distortion of the π-conjugated surface. The consequences of distortion in octulene were explored using photophysical methods, which revealed a reduced electronic band gap and greater flexibility of the π system. Octulene contains a functional cavity with a diameter larger than 5.5 Šthat is capable of efficiently binding the chloride anion in a nonpolar solvent (Ka = 2.2(4)×104 m-1 , 1 % dichloromethane (DCM) in benzene). The octulene-chloride interaction is stabilized by eight weak C(sp2 )H⋅⋅⋅Cl bonds, providing the first example of a hydrocarbon-based anion receptor.

Chrysaorenes: assembling coronoid hydrocarbons via the fold-in synthesis.

Two coronoid hydrocarbons, [3]- and [4]chrysaorene were synthesized from fluorenophane precursors using the fold-in strategy. [3]Chrysaorene is a bowl-shaped fragment of the C240-Ih fullerene, whereas [4]chrysaorene is planar and contains a unique large 24-membered internal ring. The chrysaorenes show geometry-dependent magnetic properties and are strongly fluorescent.

Changes in heart rate variability caused by coronary angioplasty depend on the localisation of coronary lesions.

BACKGROUND: Coronary angioplasty (PTCA) is a common treatment method in patients with coronary heart disease, but its effects on heart rate variability (HRV) have not been well established. AIM: To verify whether the localisation of coronary lesion undergoing PTCA affects HRV parameters. METHODS: Ninety six consecutive individuals underwent elective coronary angiography with subsequent ad hoc successful PTCA. Two five-minute ECG were recorded, one before PTCA and the second 24-hour after PTCA. The HRV indices were determined by means of classical and 'new' mathematical models. RESULTS: The PTCA-induced changes in HRV variables depended on the localisation of dilated lesion. PTCA of the circumflex artery revealed the most significant HRV changes--a decrease in value of domain indices: Yeh DI (0.033+/-0.031 vs. 0.011+/-0.006 un/unitless, p=0.005), Yeh II (0.053+/-0.039 vs. 0.032+/-0.013 un, p=0.017), Organ BAND (9.101+/-9.245 vs. 4.62+/-2.205 bpm/beat per minute, p=0.031), Huey STV (208.821+/-262.248 vs. 76.444+/-35.281 bpm, p=0.013), Dalton MABB (15.733+/-16.575 vs. 7.57+/-4.89 ms, p=0.015), Dalton SD (48.741+/-37.468 vs. 27.759+/-10.533 ms, p=0.015), Zugaib STV (0.0129+/-0.0132 vs. 0.005+/-0.003 un, p=0.005), SDNN (27.204+/-18.592 vs. 21.329+/-32.784 ms, p=0.044), rMSSD (56.239+/-19.751 vs. 51.496+/-43.889 ms, p=0.025) and increased LF/HF (2.384+/-2.072 vs. 5.632+/-5.379 un, p=0.044). Angioplasty of the right coronary artery resulted in decreased AR TP (18.273+/-2.296 vs. 17.085+/-2.256 ms(2), p=0.017) and alteration of the sympathovagal balance of the autonomic nervous system towards predominance of sympathetic activity: AR LF (0.264+/-0.029 vs. 0.284+/-0.040 un, p=0.007), LF/HF (4.310+/-4.457 vs. 6.958+/-7.013 un, p=0.018), HF (0.199+/-0.165 vs. 0.141+/-0.157 un, p=0.031), AR HF (0.647+/-0.043 vs. 0.621+/-0.054 un, p=0.014). PTCA of the left anterior descending artery caused no change. CONCLUSION: Changes in heart rate variability caused by coronary angioplasty depend on the localisation of coronary lesions.

Transcardiac release of soluble adhesion molecules during coronary artery bypass grafting: effects of crystalloid and blood cardioplegia.

BACKGROUND: Dysfunction of myocardium as a result of ischemia/reperfusion during coronary artery bypass grafting (CABG) is currently one of the biggest problems in cardiovascular surgery. In previous studies, it has been well established that activated leukocytes and coronary vascular endothelial cells play an important role in the development of cardiac tissue damage during ischemia followed by reperfusion. Interactions between both of these cell types require the expression of adhesion molecules on their surface. In certain conditions, on cell activation, the adhesion proteins may be released from activated cells in soluble form into circulation. The purpose of our study was to establish whether the use of blood cardioplegia modifies plasma levels of soluble intracellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble E-selectin (sE-selectin), and soluble L-selectin (sL-selectin) in comparison with crystalloid cardioplegia in patients undergoing CABG. METHODS: Patients undergoing CABG were classified into two groups to receive cold crystalloid cardioplegia (St. Thomas' Hospital) or cold blood cardioplegia (method of Buckberg), followed by a "warm-shot" of the solution. Coronary sinus and arterial blood samples were obtained from 50 patients (42 men and 8 women; age range, 34 to 73 years) before aortic cross-clamping, at the beginning of reperfusion, and after 30 min of reperfusion. Plasma levels of soluble adhesion molecules were measured using sensitive enzyme-linked immunosorbent assays. RESULTS: The transcardiac release of sICAM-1 and sVCAM-1 following myocardial ischemia/reperfusion during CABG was evident in both groups of patients. However, the increase of soluble forms of both of these adhesion proteins was more significant in the group of patients receiving crystalloid cardioplegia. Crystalloid cardioplegia resulted in decreased plasma level of sE-selectin in the coronary sinus blood sample after 30 min of reperfusion. No significant changes in plasma levels of sL-selectin in either group were observed. CONCLUSION: Cardioplegia may affect the release of soluble forms of adhesion molecules from ischemic myocardium and modify endothelium activation in patients undergoing CABG.