Monitoring the substrate-induced spin-state distribution in a Cobalt(II)-Salen complex by EPR and DFT

Ground state changes of (R,R’)-N,N’-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II), following coordination of various pyridyl substrate has been examined by CW EPR, pulsed relaxation measurements and DFT. The solution-based Co(II) complex possesses a low spin (LS) state urn:x-wiley:14341948:media:ejic202101071:ejic202101071-math-0001 (with g-values of 1.96, 1.895, 3.14). Upon coordination of the pyridyl substrate, the resulting bound adduct reveals a distribution of LS ‘base-on’ species, possessing a urn:x-wiley:14341948:media:ejic202101071:ejic202101071-math-0002 electronic ground state (with g-values of 2.008, 2.2145, 2.46) and a high spin (HS) species (with geff = 4.6). DFT indicated that the energy gap between the LS and HS state is dramatically lowered (ΔE < 25 kJmol−1) following substrate coordination. DFT suggests the main geometrical difference between the LS and HS systems is the severe puckering of the N2O2 ligand backbone. The results revealed a tentative dependency on the pKa−H of the substrates for the spin distribution where, in most cases, the higher pKa−H substrate values favoured the HS species

Design considerations of a dual mode X-band EPR resonator for rapid in-situ microwave heating

This paper describes the design considerations for a dual mode X-band continuous wave (CW) Electron Paramagnetic Resonance (EPR) cavity, for simultaneous EPR measurement and microwave heating of the same sample. An elliptical cavity geometry is chosen to split the degeneracy of the TM110 mode, allowing for a well resolved EPR signal with the TM110,a and TM110,b modes resonating at around 10 GHz and 9.5 GHz, respectively, the latter of which is used for EPR measurements. This geometry has the benefit that the TM010 mode used for microwave heating resonates at 6.1 GHz, below the cut off frequency of the X-band waveguide used for the EPR channel, providing effective isolation between the heating and EPR channels. The use of a pair of 9 µm thick copper clad laminates as the flat cavity walls allows for sufficient penetration of the modulation field (Bmod) into the cavity, as well as maintaining a high cavity Q factor (> 5700) for sensitive EPR measurements. Locating the heating port at an angle of 135° to the EPR port provides additional space for easier coupling adjustment and for larger sample access to be accommodated. The associated decrease of EPR signal strength is fully compensated for by using a 7.2 GHz low pass filter on the heating port. EPR spectra using 1.6 mm and 4.0 mm sample tubes are shown at room temperature (298 K) and 318 K for a standard Cu(acac)2 solution, demonstrating the effectiveness of this dual-mode EPR cavity for microwave heating during EPR detection

Ball-milling-enabled reactivity of manganese metal

Efforts to generate organomanganese reagents under ball-milling conditions have led to the serendipitous discovery that manganese metal can mediate the reductive dimerization of arylidene malonates. The newly uncovered process has been optimized and its mechanism explored using CV measurements, radical trapping experiments, EPR spectroscopy, and solution control reactions. This unique reactivity can also be translated to solution whereupon pre-milling of the manganese is required

Targeted gene panel screening is an effective tool to identify undiagnosed late onset Pompe disease

Mutations in the GAA gene may cause a late onset Pompe disease presenting with proximal weakness without the characteristic muscle pathology, and therefore a test for GAA activity is the first tier analysis in all undiagnosed patients with hyperCKemia and/or limb-girdle muscular weakness. By using MotorPlex, a targeted gene panel for next generation sequencing, we analyzed GAA and other muscle diseasegenes in a large cohort of undiagnosed patients with suspected inherited skeletal muscle disorders (n = 504). In this cohort, 275 patients presented with limb-girdle phenotype and/or an isolated hyperCKemia. Mutational analysis identified GAA mutations in ten patients. Further seven affected relatives were identified by segregation studies. All the patients carried the common GAA mutation c.-32-13T > G and a second, previously reported mutation. In the subcohort of 275 patients with proximal muscle weakness and/or hyperCKemia, we identified late-onset Pompe disease in 10 patients. The clinical overlap between Pompe disease and LGMDs or other skeletal muscle disorders suggests that GAA and the genes causing a metabolic myopathy should be analyzed in all the gene panels used for testing neuromuscular patients. However, enzymatic tests are essential for the interpretation and validation of genetic results. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe

Development of a dual-mode microwave-EPR cavity for studies of paramagnetic systems

There are many challenges when studying the mechanisms and speciation of inter-mediates formed during chemical reaction pathways. Often within many of these systems radical species are formed, making EPR spectroscopy the ideal analytical tool. However, studying such systems in-situ can be complicated by the short-lived nature of some paramagnetic species, with the study of such systems under non-equilibrium conditions near impossible. For example, when studying excited states, or to alter the product distribution and proportion of unstable species, this requires the development of new measurement techniques or hardware capabilities. For the first time, this Thesis will detail the development a dual-mode EPR cavity which has been designed and developed for simultaneous dielectric heating and EPR detection. The utilisation of the incredibly efficient heating capabilities of microwaves to generate volumetric heating and temperature jumps (T-jumps) has initially been tested, to better understand the proposed role of microwaves in enhancing the rate of reactions and chemical transformations. Specifically, the ca. 9.5 GHz TM110 mode of the EPR cavity will monitor the EPR response to the dielectric heating effects produced from a second lower frequency, ca. 6.1 GHz TM010. The design and proof of concept of three iterations of dual-mode cavities has been extensively examined, alongside alterations of specific elements within their design and the corresponding experimental implications. Notably, the movement of the 6.1 GHz heating port 135° in the second- and third-generation with respect to the 9.5 GHz port has been monitored. Without the use of a low pass filter, the signal-to-noise ratio (SNR) of the resulting EPR spectra is destroyed, due to interference between the two modes, which was not possible when the heating port was located 90° to the EPR port in the first-generation cavity. Proof that dielectric heating was successful was monitored by alterations in rotational diffusion tensors involving a spin-labelled micelle, and rotational correlation times of a small transition metal complex from room temperature to elevated temperatures. Methods of accurately determining sample temperature during dielectric heating have been examined, with potential limitations to the various techniques identified. Specifically, the temperature readings using an external thermal imaging camera severely fluctuate when altering its location and positioning. An alternative gauge of temperature was used in the form of a fiberoptic probe, which was inserted into the sample tube. Using this approach, a sample temperature gradient was identified, highlighting the importance of accurate probe placement when determining sample temperature, however this was proved to be the iii best approach to determine the temperature of the sample. The capabilities of such dual-mode cavities has been explored by comparing the thermal decomposition of 2,2’-Azobis(2-methylpropionitrile) (AIBN) in a toluene solution, under conventional and dielectric heating methods. The increased efficiency of dielectric heating was confirmed through monitoring heating rates and corresponding radical products produced. Key considerations before drawing conclusions regarding dielectric heating have been identified. Explicitly, understanding the chemical kinetics of the reaction compared to recorded heating rates prior to analysing product distribution through EPR detection when using dielectric heating. Finally, a preliminary test on a solution-based cobalt spin-crossover (SCO) complex has been conducted, observing the changes in the low-/high-spin (LS/HS) distribution upon altering the pKa-H of an axially bound pyridyl ligand. It was observed that overall, the higher the pKa-H of the pyridyl substrate, the lower the LS/HS energy gap of the overall cobalt complex, confirmed by Density Functional Theory (DFT) calculations, alongside a more intense HS EPR signal. This represent an initial investigation into ligand mediated SCO, with the aim to study such systems in the future using the dual-mode cavity, monitoring any alterations in the SCO or spin-distribution event upon dielectric heating

Influence of Cold Storage on Pear Physico-Chemical Traits and Antioxidant Systems in Relation to Superficial Scald Development

Superficial scald is the most common physiological disorder in apples and pears and causes huge economic losses worldwide. The aim of this study is to determine the different scald susceptibilities of seven pear cultivars/selections during five months of cold storage (CS). Four advanced pear selections and three commercial cultivars were harvested from an orchard located in Emilia-Romagna region, and cold stored at &minus;1 &deg;C and 85% relative humidity (RH).After 90, 120, and 150 days, fruits of each cultivar and selection were removed for ripening for 4 d, after which scald damage, physico-chemical and nutraceutical traits, and enzymatic antioxidant systems were evaluated on peel and pulp. &lsquo;Abb&eacute; F&eacute;tel&rsquo;, &lsquo;Falstaff&rsquo;, and &lsquo;CREA 171&rsquo; did not showed superficial scald symptoms after 90 days, while &lsquo;Doyenne du Comice&rsquo; and &lsquo;CREA 264&rsquo; showed the highest susceptibility. After 90 days, CS &lsquo;Falstaff&rsquo; and &lsquo;CREA 179&rsquo; showed the highest total polyphenol content (TPH) in peel, followed by &lsquo;Doyenne du Comice&rsquo; and &lsquo;Abb&eacute;F&eacute;tel&rsquo;; lowest TPH was detected in &lsquo;CREA 264&rsquo;. After 120 and 150 days of CS, &lsquo;Abb&eacute; F&eacute;tel&rsquo; and &lsquo;CREA 171&rsquo; showed the highest peel TPH. &lsquo;CREA 264&rsquo; and &lsquo;CREA 125&rsquo; reached the lowest values of TPH during the three CS time periods. Superoxide dismutase and catalase activities were higher in the peel of scald-resistant than that in scald-susceptible pear cultivars/advanced selections. Superficial scald induced an increase in polyphenoloxidase, and guaiacol peroxidase activities involved in fruit-browning during CS. Furthermore, we observed an increase in lipoxygenase activity and consequent membrane damage in both the peel and flesh of the fruit. This study indicates that pear cultivars/advanced selections have different superficial scald susceptibilities that enable them to induce the activity of several antioxidant enzymes, following CS

Ball Milling Enabled Reactivity of Manganese Metal

Efforts to generate organomanganese reagents under ball milling conditions have led to the serendipitous discovery that manganese metal can mediate the reductive dimerization of arylidene malonates. The newly uncovered process has been optimized and its mechanism explored using CV measurements, radical trapping experiments, EPR spectroscopy and solution control reactions. This unique reactivity can also be translated to solution where upon pre-milling of the manganese is required

Il riparo del Cuel (Cimbergo, BS) tra frequentazione protostorica e pitture parietali

Between 2008 and 2015 the Soprintendenza Archeologia della Lombardia performed two excavation campaigns at the Cuel rockshelter, located in the municipal area of Cimbergo, in Valle Camonica (BS), known since the 1990s for two painted figures on top of the rock wall, right above the shelter. This paper presents new unpublished data from the diggings, along with the results of the analyses on the sediments and a 14C dating, a typological analysis of the material culture and a stylistic consideration of the painted figures. The excavations documented a sequence of 4 phases of frequentation: the first human presence is evidenced by a carbonaceous layer and several copper slag, dated to the 9th-8th centuries BCE. After a hiatus, the site was re-occupied in the 6th century BCE, and a sequence of five fireplaces, all constructed in the same peculiar fashion, were created inside the small shelter. The close proximity of these structures, along with their particular shape and the analyses carried out on their contents, suggests that their use was somehow related to some sort of cultic or symbolic occurrence. The painted figures on top of the rock, which do not have physical contact with the archaeological layers, are painted in red, and depict a deer with semi-folded legs and short antlers along with an almost fully erased anthropomorphic figure. These figures are stylistically akin to other painted scenes in the area of Paspardo, which are dated to the final Iron Age (2nd-1st century BC), so there is no clear chronological link between the material use at the site and the paintings. The last stage of habitation appears to be from the middle ages, dated from the find of a silver coin found in the 2008 excavations

An in-situ study of the thermal decomposition of 2,2'-azobis(2-methylpropionitrile) radical chemistry using a dual-mode EPR resonator

A custom-built dual-mode EPR resonator was used to study the radical chemistry of AIBN thermal decomposition. This resonator enables both simultaneous in situ heating using microwaves and EPR measurements to be performed. The thermal decomposition of AIBN was compared following conventional heating methods and microwave-induced (or dielectric) heating methods. Under both heating conditions, the radicals formed and detected by EPR include the 2-cyano-2-propyl (CP●) and 2-cyano-2-propoxyl (CPO●) radicals. Under aerobic conditions, the observed relative distribution of these radicals as observed by EPR is similar following slow heating by conventional or dielectric methods. In both conditions, the kinetically favoured CPO● radicals and their adducts dominate the EPR spectra up to temperatures of approximately 80–90 °C. Under anaerobic conditions, the distribution can be altered as less CPO● is available. However, the observed results are notably different when rapid heating (primarily applied using a MW-induced T-jump) is applied. As the higher reaction temperatures are achieved on a faster timescale, none of the ST●-CPO adducts are actually visible in the EPR spectra. The more rapid and facile heating capabilities created by microwaves may therefore lead to the non-detection of radical intermediates compared to experiments performed using conventional heating methods

PFOA, PFHxA and C6O4 differently modulate the expression of CXCL8 in normal thyroid cells and in thyroid cancer cell lines

: Industrial chemical PFAS are persistent pollutants. Long chain PFAS were taken out of production due to their risk for human health, however, new congeners PFAS have been introduced. The in vitro effects of the long-chain PFOA, the short-chain PFHxA and the new-generation C6O4 were evaluated in normal and in thyroid cancer cell lines in terms of cell viability and proliferation, and secretion of a pro-tumorigenic chemokine (CXCL8), both at the mRNA and at the protein level. The Nthy-ory 3-1 normal-thyroid cell line, the TPC-1 and the 8505C (RET/PTC rearranged and BRAFV600e mutated, respectively) thyroid-cancer cell lines were exposed to increasing concentrations of each PFAS in a time-course. We evaluated viability using WST-1 (confirmed by AnnexinV/PI) and proliferation using the cristal-violet test. To evaluate CXCL8 mRNA we used RT-PCR and measured CXCL8 in the supernatants by ELISA. The exposure to none PFAS did not affect thyroid cells viability (except for a reduction of 8505C cells viability after 144 h) or proliferation. Individual PFAS differently modulated CXCL8 mRNA and protein level. PFOA increased CXCL8 both at mRNA and protein level in the three cell lines; PFHxA increased CXCL8 mRNA in the three cell lines, but increased the protein only in TPC-1 cells; C6O4 increased the CXCL8 mRNA only in thyroid cancer cell lines, but never increased the CXCL8 protein. The results of the present study indicate that the in vitro exposure to different PFAS may modulate both at the mRNA and secreted protein levels of CXCL8 in normal and cancer thyroid cells. Strikingly different effects emerged according to the specific cell type and to the targeted analyte (CXCL8 mRNA or protein)