Core-electron contributions to the molecular magnetic response

Orbital contributions to the magnetic response depend on the method used to compute them. Here, we show that dissecting nuclear magnetic shielding tensors using natural localized molecular orbitals (NLMOs) leads to anomalous core contributions. The arbitrariness of the assignment might significantly affect the interpretation of the magnetic response of nonplanar molecules such as C-60 or [14]helicene and the assessment of their aromatic character. We solve this problem by computing the core- and sigma-components of the induced magnetic field (and NICS) and the magnetically induced current density by removing the valence electrons (RVE). We estimate the core contributions to the magnetic response by performing calculations on the corresponding highly charged molecules, such as C6H630+ for benzene, using gauge-including atomic orbitals and canonical molecular orbitals (CMOs). The orbital contributions to nuclear magnetic shielding tensors are usually estimated by employing a natural chemical shielding (NCS) analysis in NLMO or CMO bases. The RVE approach shows that the core contribution to the magnetic response is small and localized at the nuclei, contrary to what NCS calculations suggest. This may lead to a completely incorrect interpretation of the magnetic sigma-orbital response of nonplanar structures, which may play a major role in the overall magnetic shielding of the system. The RVE approach is thus a simple and inexpensive way to determine the magnetic response of the core- and sigma-electrons.Peer reviewe

Introducing the INSIGNIA project: environmental monitoring of pesticide use through honey bees

INSIGNIA aims to design and test an innovative, non-invasive, scientifically proven citizen science environmental monitoring protocol for the detection of pesticides by honey bees. It is a 30-month pilot project initiated and financed by the EC (PP-1-1-2018; EC SANTE). The study is being carried out by a consortium of specialists in honey bees, apiculture, statistics, analytics, modelling, extension, social science and citizen science from twelve countries. Honey bee colonies are excellent bio-samplers of biological material such as nectar, pollen and plant pathogens, as well as non-biological material such as pesticides or airborne contamination. Honey bee colonies forage over a circle of 1 km radius, increasing to several km if required, depending on the availability and attractiveness of food. All material collected is accumulated in the hive.The honey bee colony can provide four main matrices for environmental monitoring: bees, honey, pollen and wax. Because of the non-destructive remit of the project, for pesticides, pollen is the focal matrix and used as trapped pollen and beebread in this study. Although beeswax can be used as a passive sampler for pesticides, this matrix is not being used in INSIGNIA because of its polarity dependent absorbance, which limits the required wide range of pesticides to be monitored. Alternatively, two innovative non-biological matrices are being tested: i) the “Beehold tube”, a tube lined with the generic absorbent polyethylene-glycol PEG, through which hive-entering bees are forced to pass, and ii) the “APIStrip” (Absorbing Pesticides In-hive Strips) with a specific pesticide absorbent which is hung between the bee combs.Beebread and pollen collected in pollen traps are being sampled every two weeks to be analysed for pesticide residues and to record foraging conditions. Trapped pollen provides snapshots of the foraging conditions and contaminants on a single day. During the active season, the majority of beebread is consumed within days, so beebread provides recent, random sampling results. The Beehold tube and the APIStrips are present throughout the 2-weeks sampling periods in the beehive, absorbing and accumulating the incoming contaminants. The four matrices i.e. trapped pollen, beebread, Beehold tubes and APIStrips will be analysed for the presence of pesticides. The botanical origin of trapped pollen, beebread and pollen in the Beehold tubes will also be determined with an innovative molecular technique. Data on pollen and pesticide presence will then be combined to obtain information on foraging conditions and pesticide use, together with evaluation of the CORINE database for land use and pesticide legislation to model the exposure risks to honey bees and wild bees. All monitoring steps from sampling through to analysis will be studied and rigorously tested in four countries in Year 1, and the best practices will then be ring-tested in nine countries in Year 2. Information about the course of the project, its results and publications will be available on the INSIGNIA website www.insignia-bee.eu and via social media: on Facebook (https://www.facebook.com/insigniabee.eu/); Instagram insignia_bee); and Twitter (insignia_bee). Although the analyses of pesticide residues and pollen identification will not be completed until December 2019, in my talk I will present preliminary results of the Year 1 sampling.info:eu-repo/semantics/publishedVersio

Introducing the INSIGNIA project: Environmental monitoring of pesticides use through honey bees

INSIGNIA aims to design and test an innovative, non-invasive, scientifically proven citizen science environmental monitoring protocol for the detection of pesticides via honey bees. It is a pilot project initiated and financed by the European Commission (PP-1-1-2018; EC SANTE). The study is being carried out by a consortium of specialists in honey bees, apiculture, chemistry, molecular biology, statistics, analytics, modelling, extension, social science and citizen science from twelve countries. Honey bee colonies are excellent bio-samplers of biological material such as nectar, pollen and plant pathogens, as well as non-biological material such as pesticides or airborne contamination. Honey bee colonies forage over a circle of about 1 km radius, increasing to several km if required depending on the availability and attractiveness of food. All material collected is concentrated in the hive, and the honey bee colony can provide four main matrices for environmental monitoring: bees, honey, pollen and wax. For pesticides, pollen and wax are the focal matrices. Pollen collected in pollen traps will be sampled every two weeks to record foraging conditions. During the season, most of pollen is consumed within days, so beebread can provide recent, random sampling results. On the other hand wax acts as a passive sampler, building up an archive of pesticides that have entered the hive. Alternative in-hive passive samplers will be tested to replicate wax as a “pesticide-sponge”. Samples will be analysed for the presence of pesticides and the botanical origin of the pollen using an ITS2 DNA metabarcoding approach. Data on pollen and pesticides will be then be combined to obtain information on foraging conditions and pesticide use, together with evaluation of the CORINE database for land use and pesticide legislation to model the exposure risks to honey bees and wild bees. All monitoring steps from sampling through to analysis will be studied and tested in four countries in year 1, and the best practices will then be ring-tested in nine countries in year 2. Information about the course of the project and its results and publications will be available in the INSIGNIA website www.insignia-bee.eu.info:eu-repo/semantics/publishedVersio

Induced Magnetic Field of Fullerenes: Role of σ- and π- Contributions to Spherical Aromatic, Nonaromatic, and Antiaromatic Character in C₆₀^<i>q</i> (<i>q</i> = +10, 0, −6, −12), and Related Alkali-Metal Decorated Building Blocks, Li₁₂C₆₀ and Na₆C₆₀

The induced magnetic field of fullerenes is strongly dependent on the charge state, where C₆₀ is depicted as a nonaromatic species, in contrast to C₆₀¹⁰⁺ which exhibits a strong spherical aromatic character. Here, we account for the response of relevant charged stable building blocks for novel extended networks with variable applications, as observed in A₁₂C₆₀ and A₆C₆₀ phases (A = alkali metal), given by, Li₁₂C₆₀ and Na₆C₆₀, as well as four different charge states of C₆₀^<i>q</i> (<i>q</i> = +10, 0, −6, −12), to an external magnetic field is studied in detail, focusing on the contributions from the π and σ systems to the induced magnetic field. C₆₀, C₆₀^6–, and C₆₀^12– accounts for the variation of their isolated species upon addition of charge, whereas C₆₀¹⁰⁺ is a hypothetical highly aromatic counterpart. Our results show that each spherical shell and each canonical molecular orbital exhibit characteristic patterns, revealing the direct dependence of the magnetic response, and therefore of spherical aromatic character, with regard to electron configuration. In particular, low-lying S, P, D, and F π-type shells exhibit identical strong and long-range shielding character among the four charge states. The G shell exhibits a weak shielding response, precluding the strong deshielding contribution from high-lying H and I shells. A similar analysis is given for σ-type orbitals. Thus, the aromatic, nonaromatic, and antiaromatic character of C₆₀ among the different charge states is ruled by the population of the high-lying π-shells, which is explained in terms of π → π* excitations of high-lying canonical molecular orbitals. Hence, in spherical aromatic fullerenes, the formation of a shielding cone is given mainly by the π-type shells, extending characteristic features from planar aromatics to three-dimensional structures, which is useful for further rationalization and characterization of spherical/nonaromatic and antiaromatic spherical structures

Morphological Discrimination of Greek Honey Bee Populations Based on Geometric Morphometrics Analysis of Wing Shape

Honey bees collected from 32 different localities in Greece were studied based on the geometric morphometrics approach using the coordinates of 19 landmarks located at wing vein intersections. Procrustes analysis, principal component analysis, and Canonical variate analysis (CVA) detected population variability among the studied samples. According to the Principal component analysis (PCA ) of pooled data from each locality, the most differentiated populations were the populations from the Aegean island localities Astypalaia, Chios, and Kythira. However, the populations with the most distant according to the canonical variate analysis performed on all measurements were the populations from Heraklion and Chania (both from Crete island). These results can be used as a starting point for the use of geometric morphometrics in the discrimination of honey bee populations in Greece and the establishment of conservation areas for local honey bee populations

A pictorial visualization of normal mode vibrations of the fullerene C_60 molecule in terms of vibrations of a hollow sphere

Understanding the normal mode vibrations of a molecule is important in the analysis of vibrational spectra. However, the complicated 3D motion of large molecules can be difficult to interpret. We show how images of normal modes of the fullerene molecule C60 can be made easier to understand by superimposing them on images of the normal mode vibrations of a thin spherical shell. We describe an interactive demonstration that allows the normal mode to be viewed with or without the shell. The images of the normal modes can be reoriented, and animated to show the vibration. In addition, supporting information includes images of all 174 normal modes of C60 in a common orientation, each of which can be animated. The ideas could be applied to other molecules in which the atoms all lie close to the surface of a sphere

Interpretation of Electron Delocalization in Benzene, Cyclobutadiene, and Borazine Based on Visualization of Individual Molecular Orbital Contributions to the Induced Magnetic Field

The magnetic response of the valence molecular orbitals (MOs) of benzene, cyclobutadiene, and borazine to an external magnetic field has been visualized by calculating the chemical shielding in two-dimensional grids of points on the molecular plane and on a plane perpendicular to it, using gauge-including atomic orbitals (GIAOs). The visualizations of canonical MO contributions to the induced magnetic field (CMO-IMF) provide a clear view of the spatial extension, the shape, and the magnitude of shielding and deshielding areas within the vicinity of the molecule, originating from the induced currents of each valence orbital. The results are used to investigate the delocalization of each valence MO and to evaluate its contribution to the aromatic character of systems under study. The differentiation of the total magnetic response among the three molecules originates exclusively from π-HOMO orbitals because the magnetic response of the subsets of the remaining MOs is found to be almost identical. Borazine is classified as nonaromatic as the four electrons that occupy the π-HOMO are found to be strongly localized on nitrogen centers. CMO-IMF can clarify the interpretation of various NICS indexes and can be applied for the investigation of various types of electron delocalization

The Impact of Vairimorpha (Nosema) ceranae Natural Infection on Honey Bee (Apis mellifera) and Bee Bread Microbiota

Honey bees face new challenges, ranging from climate crisis to emerging pathogens such as Vairimorpha (Nosema) ceranae that synergistically cause a syndrome designated as colony collapse disorder (CCD). This study employed a metataxonomic approach in order to investigate if V. ceranae affects gut microbiota (bacteria and fungi) of adult A. mellifera honey bees as well as microbiota of bee bread (BB) stored in colonies demonstrating severe V. ceranae infection (spore counts >2,500,000 per bee) as compared with colonies exhibiting very low spore counts (<40,000 per bee). Alpha-diversity analysis revealed an overall decrease in microbial diversity reflected by number of observed unique operating taxonomic units (OTUs) regarding both bacteria and fungi in honey bee and ΒΒ samples. Further analysis demonstrated that Podosphaera spp. were absent in BB samples collected from colonies with high spore counts, while relative abundance of Blumeria spp. was significantly decreased. Interestingly, relative abundance of Rosenbergiella spp. was increased in BB samples collected from colonies with high spore counts. The reason for these findings remains elusive. Although further research is warranted, overall reduced microbial diversity and relative abundance of certain microbial groups may serve as biomarkers of colony collapse. © 2022 by the authors