Zinc(II)-methimazole complexes: synthesis and reactivity

The tetrahedral S-coordinated complex [Zn(MeImHS)(4)](ClO4)(2), synthesised from the reaction of [Zn(ClO4)(2)] with methimazole (1-methyl-3H-imidazole-2-thione, MeImHS), reacts with triethylamine to yield the homoleptic complex [Zn(MeImS)(2)] (MeImS = anion methimazole). ESI-MS and MAS C-13-NMR experiments supported MeImS acting as a (N, S)-chelating ligand. The DFT-optimised structure of [Zn(MeImS)(2)] is also reported and the main bond lengths compared to those of related Zn-methimazole complexes. The complex [Zn(MeImS)(2)] reacts under mild conditions with methyl iodide and separates the novel complex [Zn(MeImSMe)(2)I-2] (MeImSMe = S-methylmethimazole). X-ray diffraction analysis of the complex shows a ZnI2N2 core, with the methyl thioethers uncoordinated to zinc. Conversely, the reaction of [Zn( MeImS)(2)] with hydroiodic acid led to the formation of the complex [Zn(MeImHS)(2)I-2] having a ZnI2S2 core with the neutral methimazole units S-coordinating the metal centre. The Zn-coordinated methimazole can markedly modify the coordination environment when changing from its thione to thionate form and vice versa. The study of the interaction of the drug methimazole with the complex [Zn(MeIm)(4)](2+) (MeIm = 1-methylimidazole) - as a model for Zn-enzymes containing a N-4 donor set from histidine residues shows that methimazole displaces only one of the coordinated MeIm molecules; the formation constant of the mixed complex [Zn(MeIm)(3)(MeImHS)](2+) was determined

Seasonal variation in vitamin D status of beef cattle reared in the central United States

The objective was to retrospectively measure seasonal sunlight-associated variation in serum concentrations of 25-hydroxyvitamin D (25OHD) in beef cattle. The concentration of 25OHD was measured in crossbred animals born from March to May in 2011 and 2012. Vitamin D status 2 to 3 mo after birth (period 1) was only available for 2012 calves and was measured in June 2012. Period 1 animals had serum 25OHD concentrations of 26.3 +- 1.5 ng/mL. The 25OHD concentrations for late summer (period 2) were 46.6 +- 1.4 and 51.0 +- 1.5 ng/mL for 2011 and 2012, respectively. Serum concentration of 25OHD in early fall (period 3) were 63.8 +- 1.4 and 55.2 +- 1.5 ng/mL for calves in 2011 and 2012, respectively. Values observed for both late summer and early fall indicated vitamin D sufficiency (P \u3c 0.001) compared with period 1. With diminishing exposure to ultraviolet B and consuming w800 IU or 1800 IU (2011 and 2012, respectively) of supplemental vitamin D, the calves’ midwinter (period 4) 25OHD concentrations fell to 15.2 +- 1.6 and 16.7 +- 1.5 ng/mL for 2011 and 2012, respectively, after 4 to 5 mo on a finishing diet (P \u3c 0.0001). This is considered vitamin D insufficiency in most species. Results indicate that calves are marginally sufficient to insufficient for vitamin D based on serum 25OHD concentrations soon after birth and during winter. Some individual animals would be classified vitamin D deficient. In the absence of sufficient UVB exposure, the dietary vitamin D requirements for rapidly growing beef cattle may need to be increased

Seasonal variation in vitamin D status of beef cattle reared in the central United States

The objective was to retrospectively measure seasonal sunlight-associated variation in serum concentrations of 25-hydroxyvitamin D (25OHD) in beef cattle. The concentration of 25OHD was measured in crossbred animals born from March to May in 2011 and 2012. Vitamin D status 2 to 3 mo after birth (period 1) was only available for 2012 calves and was measured in June 2012. Period 1 animals had serum 25OHD concentrations of 26.3 +- 1.5 ng/mL. The 25OHD concentrations for late summer (period 2) were 46.6 +- 1.4 and 51.0 +- 1.5 ng/mL for 2011 and 2012, respectively. Serum concentration of 25OHD in early fall (period 3) were 63.8 +- 1.4 and 55.2 +- 1.5 ng/mL for calves in 2011 and 2012, respectively. Values observed for both late summer and early fall indicated vitamin D sufficiency (P \u3c 0.001) compared with period 1. With diminishing exposure to ultraviolet B and consuming w800 IU or 1800 IU (2011 and 2012, respectively) of supplemental vitamin D, the calves’ midwinter (period 4) 25OHD concentrations fell to 15.2 +- 1.6 and 16.7 +- 1.5 ng/mL for 2011 and 2012, respectively, after 4 to 5 mo on a finishing diet (P \u3c 0.0001). This is considered vitamin D insufficiency in most species. Results indicate that calves are marginally sufficient to insufficient for vitamin D based on serum 25OHD concentrations soon after birth and during winter. Some individual animals would be classified vitamin D deficient. In the absence of sufficient UVB exposure, the dietary vitamin D requirements for rapidly growing beef cattle may need to be increased

A structural spproach to the strength evaluation of linear chalcogen bonds

The experimental structural features of chalcogen bonding (ChB) interactions in over 34,000 linear fragments R–Ch⋯A (Ch = S, Se, Te; R = C, N, O, S, Se, Te; A = N, O, S, Se, Te, F, Cl, Br, I) were analyzed. The bond distances dR–Ch and the interaction distances dCh⋯A were investigated, and the functions δR–Ch and δCh⋯A were introduced to compare the structural data of R–Ch⋯A fragments involving different Ch atoms. The functions δR−Ch and δCh⋯A were calculated by normalizing the differences between the relevant bond dR–Ch and ChB interaction dCh⋯A distances with respect to the sum of the relevant covalent (rcovR + rcovCh) and the van der Waals (vdW) radii (rvdWCh + rvdWA), respectively. A systematic comparison is presented, highlighting the role of the chalcogen involved, the role of the R atoms covalently bonded to the Ch, and the role of the A species playing the role of chalcogen bond acceptor. Based on the results obtained, an innovative approach is proposed for the evaluation and categorization of the ChB strength based on structural data

Recurrent aphthous stomatitis: Treatment and management

Background: Recurrent aphthous stomatitis consists of the presence of abrasions or ulcerations located on mucosae (oral or genital). Objectives: The aim of this article is to review the current literature providing the main causes related to recurrent aphthous stomatitis and insights into treatment and management of this clinical condition Methods: Articles matching terms that correlated with "recurrent aphthous stomatitis"were searched on PubMed, EMBASE, and Cochrane Library and selected according to their pertinence. Results: Several forms of aphthous stomatitis have been described, based on the extent (minor, major), morphology (herpetiform) and associations to other signs (Beh\ue7et syndrome or more complex inflammatory syndromes). Topical as well as systemic treatments have been described to obtain a faster remission of the aphthosis or to reduce associated symptoms such as pain. Conclusions: Recurrent aphthous stomatitis can have a mild-to-severe clinical appearance, being mainly localized on the oral mucosa or at the level of the genital area. Different strategies have been described so far for its management and treatment

Natural Occurrence of Ochratoxin A in Blood and Milk Samples from Jennies and Their Foals after Delivery

An assessment of the natural ochratoxin A (OTA) exposure of seven Martina Franca jennies was carried out by analyzing blood and milk samples collected close to and after delivery. A total of 41 and 34 blood samples were collected from jennies and foals, respectively, and analyzed by ELISA. A total of 33 milk samples were collected from jennies and analyzed by the HPLC/FLD method based on IAC clean-up. Furthermore, 53 feed samples were collected from January to September and analyzed by a reference method (AOAC Official Method No. 2000.03) for OTA content. Feed samples showed OTA levels up to 2.7 ng/g with an incidence of 32%, while the OTA incidence rate in jennies' blood samples was 73%, with a median value of 97 ng/L and concentrations ranging fro

The digital whomanities project. Best practices for digital pedagogy in the pandemic era

This paper aims to enter the ongoing debate about the critical issues of digital pedagogy through the presentation of Digital WHOmanities, a series of online conferences and workshops held at the University of Bologna. Distance learning has become one of the most discussed topics in educational institutions during the spread of Covid-19, revealing a discrepancy between the rapid development of technology and the ability of learning environments to adapt to this turn. In view of this ongoing debate, Digital WHOmanities tried to define the complex and multifaceted figure of the digital humanist and to provide a methodological framework that could foster further online academic initiatives. Specifically, the accurate organization of timing and contents and the adoption of synchronous and asynchronous approaches have highlighted the effectiveness of flexible digital didactics

Diradical Character of Neutral Heteroleptic Bis(1,2-dithiolene) Metal Complexes: Case Study of [Pd(Me2timdt)(mnt)] (Me2timdt = 1,3-Dimethyl-2,4,5-trithioxoimidazolidine; mnt2-= 1,2-Dicyano-1,2-ethylenedithiolate)

The reaction of the bis(1,2-dithiolene) complex [Pd(Me2timdt)2] (1; Me2timdt•- = monoreduced 1,3-dimethyl-2,4,5-trithioxoimidazolidine) with Br2 yielded the complex [Pd(Me2timdt)Br2] (2), which was reacted with Na2mnt (mnt2- = 1,2-dicyano-1,2-ethylenedithiolate) to give the neutral mixed-ligand complex [Pd(Me2timdt)(mnt)] (3). Complex 3 shows an intense solvatochromic near-infrared (NIR) absorption band falling between 955 nm in DMF and 1060 nm in CHCl3 (ϵ = 10700 M-1 cm-1 in CHCl3). DFT calculations were used to elucidate the electronic structure of complex 3 and to compare it with those of the corresponding homoleptic complexes 1 and [Pd(mnt)2] (4). An in-depth comparison of calculated and experimental structural and vis-NIR spectroscopic properties, supported by IEF-PCM TD-DFT and NBO calculations, clearly points to a description of 3 as a dithione-dithiolato complex. For the first time, a broken-symmetry (BS) procedure for the evaluation of the singlet diradical character (DC) of heteroleptic bis(1,2-dithiolene) complexes has been developed and applied to complex 3. The DC, predominant for 1 (nDC = 55.4%), provides a remarkable contribution to the electronic structures of the ground states of both 3 and 4, showing a diradicaloid nature (nDC = 24.9% and 27.5%, respectively). The computational approach developed here clearly shows that a rational design of the DC of bis(1,2-ditiolene) metal complexes, and hence their linear and nonlinear optical properties, can be achieved by a proper choice of the 1,2-dithiolene ligands based on their electronic structure

Unequivocal experimental evidence of the relationship between emission energies and aurophilic interactions

In this paper we describe experimental evidence of the change in emission energy as a function of gold-gold distance. We have employed a luminescent complex exhibiting an aurophilic interaction, which is weak enough to allow its length to be modified by external pressure, but rigid enough to confer structural stability on the complex. By determining the crystal structures and emission characteristics over a range of pressures, we have identified an exponential relationship between the wavelength of the emitted light and the metal-metal distances under pressure. This result can be indirectly related to the repulsive branch of the fitted function representing the energy of the system at different gold-gold distances. The relativistic nature of gold appears to play an important role in the behaviour of this complex

Functionalization and Coordination Effects on the Structural Chemistry of Pendant Arm Derivatives of 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS3)

The effect of different pendant arms on the structural chemistry of the 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS3) macrocycle is discussed in relation to the coordination chemistry of all known functionalized derivatives of [12]aneNS3, which have been structurally characterized