Chemistry and light - part 2: light and energy

The conversion of solar energy into more useful forms of energy, such as chemical fuels or electricity, is one of the central problems facing modern science. Progress in photochemistry and chemical synthesis has led to a point where light energy conversion by means of artificial molecular devices can be rationally attempted. In this article, a general approach towards this challenging goal is presented

The Effect of the Introduced Red Wood Ant Formica paralugubris on the Frequency of Ant Nests and First Plesiobiotic Association between Myrmica ruginodis (Nylander, 1846) and Lasius flavus (Fabricius, 1782)

Red wood ants are ecologically dominant species that affect the composition of the invertebrate community. In the past century, one of these species, Formica paralugubris (Seifert 1996), was introduced outside its native area (the Alps), in the Apennines (Italy). Here we investigated the effect of the presence of an introduced population of F. paralugubris on the frequency of nests of other ant species in Abetone, Central Apennines. Ant nests were found only in the area unoccupied by F. paralugubris. In this area, we also found one pleometrotic association between queens of Lasius flavus (Fabricius, 1782) and two plesiobiotic associations, one between Formica fusca (Linnaeus, 1758) and L. flavus and the other one between Myrmica ruginodis (Nylander, 1846) and L. flavus. This latter is the first plesiobiotic relationship reported between these two species, the second reported for M. ruginodis and the 10th for L. flavus. Additionally, this is the first plesiobiotic association reported for the Mediterranean region and Southern Europe

Macchine molecolari

La costruzione di macchine di dimensioni molecolari è uno straordinario risultato scientifico e un obiettivo primario della nanotecnologia. Nel corso degli ultimi trent'anni, i chimici in varie parti del mondo hanno imparato a realizzare delle semplici macchine nanometriche. Anche se questi minuscoli dispositivi non sono ancora divenuti parte integrante della nostra vita quotidiana, siamo ormai alle soglie di una nuova rivoluzione industriale, capace di cambiare il nostro futuro con applicazioni innovative nella tecnologia dei materiali, nell'informatica, nella robotica e nella medicina

Artificial molecular-level machines with [Ru(bpy)3]2

A molecular-level machine is an assembly of a discrete number of molecular components (that is, a supramolecular structure) designed to perform mechanical-like movements (output) as a consequence of appropriate external stimuli (input). Like macroscopic machines, molecular-level machines are characterized by (i) the kind of energy input supplied to make them work, (ii) the kind of movement performed by their components, (iii) the way in which their operation can be controlled and monitored, (iv) the possibility to repeat the operation at will and establish a cyclic process, (v) the time scale needed to complete a cycle of operation, and (vi) the function performed. The most convenient way to supply energy to an artificial molecular-level machine is through a photochemical reaction.[Ru(bpy)3]2+(bpy=2,2′-bipyridine) can be used as a photosensitizer to power mechanical movements in machines based on pseudorotaxanes, rotaxanes and catenanes. Besides being used as an external photosensitizer,[Ru(bpy)3]2+can be incorporated in one of the machine components as a "light-fueled" motor. Three types of photochemically driven piston/cylinder systems and a photocontrollable molecular abacus are described. Other kinds of more sophisticated molecular-level machines based on rotaxanes and catenanes are proposed. The extension of the concept of machine to the molecular level is important not only for the sake of basic research, but also for the growth of nanoscience and the development of nanotechnology

When alien catfish meet—Resource overlap between the North American Ictalurus punctatus and immature European Silurus glanis in the Arno River (Italy)

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Palatability of glyphosate in ants: a field experiment reveals broad acceptance of highly polluted solutions in a Mediterranean ant

Glyphosate is a systemic herbicide still used in many countries, though there are several known detrimental effects on animals. Previous studies concerning its effects on social insects are available, but they are primarily focused on honeybees; little is known about the interactions of this compound with ants. Here, we assessed whether different concentrations of glyphosate can be perceived by ant workers and to what extent. As a model species, we used the Mediterranean ant Crematogaster scutellaris, commonly found in agroecosystems. We performed 3000 individual tests of acceptance using ten different solutions of various concentrations of the herbicide. Half of the solutions contained added sucrose in order to test the possible masking effect of the sugar taste on glyphosate. We used comparable glyphosate concentrations to those previously used in other studies on social insects or suggested by the producer. We found that the acceptance of the solutions decreased as the concentration of the herbicide increased. However, a significant percentage of ants drank the solutions with concentrations up to dozens of times higher than those inducing toxic effects in bees. In light of these results, we urge further assessment of the effects of glyphosate on ants, particularly because the food ingested by workers is transferred to the brood and queens, posing a potential threat to the health of the entire colony. Surprisingly, we did not record any difference in acceptance between solutions with and without sugar; this point is discussed regarding drought stress.info:eu-repo/semantics/publishedVersio

Sub-lethal doses of imidacloprid alter food selection in the invasive garden ant Lasius neglectus

Despite several restrictions to their use, neonicotinoid insecticides are still widely employed worldwide. Residual sub-lethal amounts of these chemicals can have detrimental effects on the behavior of non-target insects. Toxic effects on economically important species such as bees have been widely documented, but less is known about their toxic action on other social insects, such as ants. In this study, we assessed the effect of different sub-lethal doses of the neonicotinoid imidacloprid on the ability of colonies of the invasive ant Lasius neglectus to select the most profitable resource. We used Y-shaped mazes having an imidacloprid-polluted or an unpolluted sucrose solution on the two branches. Two sucrose (0.1 M, 0.5 M) and two imidacloprid (1 μg/ml, 10 μg/ml) concentrations were used. In parallel, we evaluated the marking activity of foragers who fed on the same solutions. We found that the 0.1 M sugar solution polluted with 1 μg/ml imidacloprid was significantly more frequently selected in binary choices experiments than the unpolluted resource. Moreover, the ingestion of the same combination of sugar and imidacloprid significantly increased the marking rate of foragers. The higher concentration of the pollutant had lower effects, probably because of the hormesis phenomenon. Results suggest that the lower sub-lethal dose of imidacloprid can lead ants to select again the polluted resource. This “active” selection of the pollutant may magnify the negative effects on the colonies. Due to their ecological role, any impairment of ant survival or behavior may have detrimental cascade effects on the whole ecosystem.info:eu-repo/semantics/publishedVersio

Cutaneous Implantation Metastasis of Cholangiocarcinoma after Percutaneous Transhepatic Biliary Drainage

Percutaneous transhepatic biliary decompression is a preoperative surgical adjunct in patients with obstructive jaundice that has been in use since 1973. It is recommended that this procedure be adopted for both palliative treatment in unresectable patients and as a preoperative means of lowering serum bilirubin in patients with potentially resectable malignancies of the pancreas or biliary tract. Metastatic tumor seeding along the transhepatic biliary catheter is an unusual complication resulting from this procedure but there have been a few cases reported in the literature. Below is a report on a 59-year-old woman in whom the percutaneous transhepatic catheter drainage of the biliary tree, performed before surgical resection of a cholangiocarcinoma, caused cutaneous tumor implantation at the catheter site 3 months later. The clinical aspect was morphea-like and histopathologic examination revealed typical features of a dermal metastasis of adenocarcinoma. Immunohistochemistry revealed cytoplasmic positivity for cytokeratin 7-19, specific for the biliary tract epithelium. A review of the literature available led us to conclude that port-site metastasis in patients with obstructive jaundice treated with percutaneous transhepatic biliary decompression was an unusual but possible complication. In fact, many catheter-tract metastatic deposits in the liver parenchyma, detected at autopsy or on operation, are mistakenly identified as hematogenous or lymphatic metastasis and are not attributed to a catheter-related process. We also report on this case because of the atypical morphea-like aspect of the skin metastasis

Giant Metatypical Carcinoma: An Unusual Tumor

Meta-typical carcinoma (MTC) or basosquamous carcinoma is a remarkable malignancy with features of both basal and squamous cell carcinoma. It is typically located on the back and face, often with clinical features of basal cell carcinoma but tending to be more aggressive with enhanced prospects of lymph node or distant metastases. Our report describes a huge neglected MTC of the back of ten-year duration, a giant ulcero-vegetative tumor measuring 20 x 25 cm. Histologic examination of specimens from the margins and periphery revealed aspects of both basal and squamous cell carcinoma, while the ulcerated center showed sclerotic tissue without tumor. Radical excision and reconstruction by grafts were performed. No metastases were observed after two years. There are many controversies surrounding the histologic definition and biologic behavior of MTC, including its metastasizing potential. The MTC we describe exhibited benign biologic behavior. This may have been related to an intense inflammatory host response with elimination of neoplastic tissue and consequent local sclerosis evident in the central tumor-free portion. This central tumor regression is to our knowledge a unique finding in MTC

Shared Histories of Co-evolution May Affect Trophic Interactions in a Freshwater Community Dominated by Alien Species

Interactions occurring between species in multiple invaded freshwater ecosystems are often difficult to observe and study. Studies on invasive alien species typically focus on single species, and, when the species community is exclusively composed of alien species, their interactions, eventual facilitation and hindering processes are very scarcely assessed. To investigate such a community, the species community in the Arno River (Tuscany, Italy) was examined as a model system using the combined approach of stable isotopes and dietary analyses. Established alien species have formed a pyramid shaped community with the European catfish Silurus glanis and the North American channel catfish Ictalurus punctatus in the apex position, followed by opportunistic predatory (Lepomis gibbosus) and omnivore (Alburnus alburnus, Cyprinus carpio, Barbus barbus, Pseudorasbora parva, Padogobius sp., Tinca tinca) species. These species were observed to feed on a variety of primary producers (Myriophyllum sp., Potamogeton sp., Phragmites australis) and consumers (aquatic insects, molluscs, Dikerogammarus villosus, Procambarus clarkii, Palaemon antennarius, tadpoles). Remarkably, the channel catfish Ictalurus punctatus showed an ontogenetic niche shift, with juveniles occupying a slightly higher trophic position than mature individuals. Pseudorasbora parva and A. alburnus showed a strong niche overlap, with the former having a wider niche. Such wide niches were also found for the invasive crustaceans D. villosus and P. clarkii. Outgoing from our findings, we suggest that life-history and geographic origin play a role in determining competition and interaction type among alien species, with species from the same geographic area showing a lower potential to compete than species from different areas, hence affecting their potential impact on native species