Structure–Activity Relationships of Benzenesulfonamide‐Based Inhibitors towards Carbonic Anhydrase Isoform Specificity

Carbonic anhydrases (CAs) are implicated in a wide range of diseases, including the upregulation of isoforms CA IX and XII in many aggressive cancers. However, effective inhibition of disease‐implicated CAs should minimally affect the ubiquitously expressed isoforms, including CA I and II, to improve directed distribution of the inhibitors to the cancer‐associated isoforms and reduce side effects. Four benzenesulfonamide‐based inhibitors were synthesized by using the tail approach and displayed nanomolar affinities for several CA isoforms. The crystal structures of the inhibitors bound to a CA IX mimic and CA II are presented. Further in silico modeling was performed with the inhibitors docked into CA I and XII to identify residues that contributed to or hindered their binding interactions. These structural studies demonstrated that active‐site residues lining the hydrophobic pocket, especially positions 92 and 131, dictate the positional binding and affinity of inhibitors, whereas the tail groups modulate CA isoform specificity. Geometry optimizations were performed on each ligand in the crystal structures and showed that the energetic penalties of the inhibitor conformations were negligible compared to the gains from active‐site interactions. These studies further our understanding of obtaining isoform specificity when designing small molecule CA inhibitors.     

Novel Sulfonated CNN Pincer Ligands for Facile C−H Activation at a Pt(II) Center

Two novel sulfonated CNN-pincer ligands 1b and 1c and the corresponding chloro and aqua complexes K[^CNNLPtCl] and ^CNNLPt(H₂O), 3b – 3c and 2b – 2c , were prepared and fully characterized including single crystal X-ray diffraction. Along with the previously described complexes 2a and 3a , the derivatives of a CNN pincer ligand 1a , these complexes form a family of structurally similar compounds where the pincer core rigidity increases in the series 2a (3a) < 2b (3b) < 2c ( 3c ), as deduced from their XRD data. The increased ligand rigidity affects the aqua ligand dissociation energy of the ^CNNLPt(H₂O) complexes, as it follows from DFT calculations and as is reflected in the increased reactivity of the aqua complexes 2a , 2b and 2c in processes that involve aqua ligand loss. Among these processes the formation of the presumed dinuclear complexes ^CNNL₂Pt₂ and, importantly, catalytic C−D bond cleavage in C₆D₆ were studied in 2,2,2-trifluoroethanol solutions. The C−D bond cleavage reactivity was quantified as the rate of H/D exchange between C₆D₆ and CF₃CH₂OH at 80 °C.     

Integrating monitoring networks to obtain estimates of ground-level ozone concentrations --a proof of concept in Tuscany (central Italy)

Prior to 2000 a network of conventional ozone (O3) analysers existed in the Province of Firenze (Tuscany, central Italy). Between 2000 and 2004 the network was extended to incorporate a newly designed bioindicator network of tobacco plants (Nicotiana tabacum Bel W3). The objective was to set-up an integrated monitoring system to obtain estimates of ground-level O3 concentrations over the whole study area (3513 km2) in order to fill data gaps and cover reporting requirements. The existing conventional monitors were purposefully located mainly in urban areas. A total of 45 biomonitoring sites were selected using a systematic design to cover the target area. Two to five additional biomonitoring sites were co-located with conventional O3 analysers for calibration purposes, and five more sites for independent validation of modelled O3 concentrations. Visible Leaf Injury Index (LII) on the tobacco plants was significantly correlated (P: 0.018/0.0014) with a series of O3 exposure variables (mean of weekly 1-hour maxima, M1; mean of 7-hour means, M7; 24-hour mean, M24; and weekly AOT40). LII was found to be a significant predictor of weekly means of the O3 exposure variables with a standard error of estimates between 13.6 and 24.3 microg m(-3) (absolute values). LII was mapped with an ad-hoc spatial model over the study area at a 22 km grid resolution, and mapped values were used to predict O3 concentrations by means of a first order linear model. Results showed that high estimates of O3 (up to 188 microg m(-3) as mean of weekly maxima, M1) occurred more frequently in hilly and mountainous areas, with a spatial pattern changing on an annual basis. Predicted O3 concentrations were not significantly different from the measured concentrations (P: 0.34), although marked differences were observed for individual sites and years. The study provided evidence that integration of monitoring networks using different methods can be a viable option to obtain estimates of O3 concentrations over large areas.     

Ultrasensitive hot-electron nanobolometers for terahertz astrophysics

The submillimetre or terahertz region of the electromagnetic spectrum contains approximately half of the total luminosity of the Universe and 98% of all the photons emitted since the Big Bang. This radiation is strongly absorbed in the Earth's atmosphere, so space-based terahertz telescopes are crucial for exploring the evolution of the Universe. Thermal emission from the primary mirrors in these telescopes can be reduced below the level of the cosmic background by active cooling, which expands the range of faint objects that can be observed. However, it will also be necessary to develop bolometers-devices for measuring the energy of electromagnetic radiation-with sensitivities that are at least two orders of magnitude better than the present state of the art. To achieve this sensitivity without sacrificing operating speed, two conditions are required. First, the bolometer should be exceptionally well thermally isolated from the environment; second, its heat capacity should be sufficiently small. Here we demonstrate that these goals can be achieved by building a superconducting hot-electron nanobolometer. Its design eliminates the energy exchange between hot electrons and the leads by blocking electron outdiffusion and photon emission. The thermal conductance between hot electrons and the thermal bath, controlled by electron-phonon interactions, becomes very small at low temperatures ( approximately 1 x 10-16 W K-1 at 40 mK). These devices, with a heat capacity of approximately 1 x 10-19 J K-1, are sufficiently sensitive to detect single terahertz photons in submillimetre astronomy and other applications based on quantum calorimetry and photon counting.     

Nanocrystal-encoded fluorescent microbeads for proteomics: antibody profiling and diagnostics of autoimmune diseases

The first application of nanocrystal (NC)-encoded microbeads to clinical proteomics is demonstrated by multiplexed detection of circulating autoantibodies, markers of systemic sclerosis. Two-color complexes, consisting of NC-encoded, antigen-covered beads, anti-antigen antibody or clinical serum samples, and dye-tagged detecting antibodies, were observed using flow cytometry assays and on the surface of single beads. The results of flow cytometry assays correlated with the ELISA technique and provided clear discrimination between the sera samples of healthy donors and patients with autoimmune disease. Microbead fluorescence signals exhibited narrow distribution regardless of their surface antigen staining, without the need of any fluorescence compensation-a parameter determining the limit of sensitivity of flow cytometry assays. In single bead measurements, less than 30 dye-labeled antibodies interacting with the topoI-specific antibodies at the surface of a bead have been detected by the emission of dye excited through the FRET from NCs. In this format, the antibody-bead interaction reaction turns specifically the fluorescence signal from dye label off and on, additionally increasing autoantibody detection sensitivity.     

Investigation of the Thermal Behaviour of Non‐metallic Curved‐Face‐Width Spur Gears

This paper describes a curved‐face‐width spur gear, specially designed for manufacture from non‐metallic materials. The benefits of this gear are the higher contact ratio, bending and Hertzian contact resistance, and greater tooth stiffness compared to standard spur gears. A modified geometry is proposed for the gear tooth, the height of which varies along the gear face width. Due to the reduction in tooth height, in sections away from the gear centre, lower sliding friction is expected, with consequences for the gear's thermal behaviour. The complex gear geometry makes the design of a die difficult; therefore the gears were cut on a milling machine, using a special kinematic generation process and related equipment. The tooth flank profile, an involute or near involute in sections away from the gear half‐width plane, as well as the flank surface quality determined by the single‐cutter tool used for gear manufacture, influence the meshing condition, and can be detrimental to the thermal behaviour of the gear. Experimental tests were carried out to examine the influence of load and speed on the temperature of the curved‐face‐width spur gears with modified geometry. The measured temperature of the non‐standard gear is further compared with the predicted temperature of plastic standard spur gears of the same specification.     

Optical and electrical characterization of a gold nanoparticle dispersion in a chiral liquid crystal matrix

We report on the effect of gold nanoparticle (Au NP) dispersion in a chiral nematic liquid crystal (LC). Polarized optical microscopy and X-ray diffraction measurements evidence the insurgence of an order change in the LC host. Moreover, a comparative analysis based on dielectric and voltammetric spectroscopies performed on pure LC and on Au NP-doped LC shows that Au NP’s presence besides affecting LC order influences its electric properties: ion conductivity results importantly reduced, and beyond a threshold value of the applied field electrophoresis phenomena are induced.     

A simplified method for the evaluation of fatigue crack front shapes under mode I loading

Two-dimensional elastic or elasto-plastic models dominate the current fatigue crack growth assessment and life prediction procedures for plate components with through-the-thickness cracks. However, as demonstrated in many theoretical and experimental papers, the stress field near the crack tip is always three-dimensional and, as a result, the fatigue crack front is not straight. It is normally curved towards the plate faces. Over the past few years there were a number of very careful numerical studies focusing on the evaluation of fatigue crack front shapes. However, the application of the direct numerical techniques to fatigue phenomena is a very tedious and time consuming process and, sometimes, it is quite ambiguous. In the current paper we develop a simplified method for the evaluation of the front shapes of through-the-thickness fatigue cracks. Further, we validate the developed method against experimental results, investigate the influence of various parameters on the crack front shapes at stable (steady-state) propagation and analyse the differences in the results of fatigue crack growth evaluation obtained with two- and three-dimensional approaches.     

Implementation of OpenFlow based cognitive radio network architecture: SDN&R

Wireless Networks - The static conventional network architecture is ill-suited to the growing management complexity and highly dynamic wireless network topologies. Software Defined Radio systems...