Realizing Caustics in Acoustic Fields

We present a method to realise a wide class of caustics in acoustic fields created by a set of phase holograms realized with metasurfaces. Given the desired caustic shape, we discuss how to identify the phase distribution along the metasurfaces and describe the calculations needed for determining the pressure field in the vicinity of the caustic. The results of this work can be used in realising acoustic traps controllable with acoustic metamaterials

Recent results in animal models of pancreatic carcinoma: histogenesis of tumors.

Animal models of carcinoma of the pancreas provide new information regarding the pathways for histogenesis of the tumors. Four models, induced by chemical carcinogens or transgenic methods, are reviewed briefly from this perspective. Recent reports indicate that carcinomas with a ductal phenotype can arise from transformed acinar cells in rodents. A transgenic mouse model provides evidence that anaplastic carcinomas and islet cell tumors may arise from primitive cells that express the elastase gene, yet retain the potential to differentiate as islet cells. In a nitrosamine-induced hamster model, ductal carcinomas appear to arise directly from ductal cells. Carcinomas in this model contained mutations in the c-K-ras oncogene that are similar to those reported in about 75 percent of human pancreatic carcinomas, whereas acinar cell carcinomas of rats lacked this mutation. The histologic type of a carcinoma may reflect the cell of origin, but this statement is not always true. Therefore, classification of tumors on the basis of phenotype rather than on the presumed cell of origin is recommended. Among the animal models, the carcinomas in hamster pancreas rank as most similar to human pancreatic ductal adenocarcinomas in regard to the phenotype of the tumors and the prevalence of the c-K-ras mutation

Plasma p-Cresol Lowering Effect of Sevelamer in Peritoneal Dialysis Patients: Evidence from a Cross-Sectional Observational Study.

p-Cresol is a by-product of the metabolism of aromatic aminoacid operated by resident intestinal bacteria. In patients with chronic kidney disease, the accumulation of p-cresol and of its metabolite p-cresyl-sulphate, that represents more than 95% of circulating p-cresol, causes endothelial dysfunction and ultimately increases the cardiovascular risk of these patients. Therapeutic strategies able to reduce plasma p-cresol levels are highly demanded but unfortunately not available yet. Because it has been reported that the phosphate binder sevelamer also sequesters p-cresol in vitro we hypothesized that it could do so also in peritoneal dialysis patients. To explore this hypothesis we measured total cresol plasma concentrations in 57 patients with end-stage renal disease on peritoneal dialysis patients, 29 receiving sevelamer for the treatment of hyperphosphatemia and 28 patients not assuming this drug. Among the patients not assuming sevelamer, 16 were treated with lanthanum whereas the remaining 12 received no drug because they were not hyperphosphatemic. When we compared total p-cresol plasma concentrations in these different groups of patients, we, we found that plasma p-cresol levels were significantly lower in patients receiving sevelamer than in subjects receiving lanthanum or no drug. Patients assuming sevelamer had also lower high sensitivity C-reactive protein serum concentrations compared to patients not assuming this drug. Multiple linear regression analysis showed that Conversely, no difference either in residual glomerular filtration rate, total weekly dialysis dose or serum phosphate levels were observed among the different groups. These results suggest that sevelamer could be an effective strategy to lower p-cresol circulating levels in peritoneal dialysis patients in which it could also favorably affect the cardiovascular risk because of its anti-inflammatory effect

Plant cover and management practices as drivers of soil quality

Human activities intensively modify soil properties and quality according to land-use and management practices. In Mediterranean areas, pollution and fires may directly alter some soil abiotic properties as well as the steady-state condition of soil microbiota. The aim of this study was to evaluate if the chemical and biological characteristics of two kinds of soil, Arenosols and Andosols, of a natural reserve and an urban park respectively, were affected by the same or different plant covers (trees and grasses). At each site, five sub-samples of surface soils (0–10 cm) were collected under maquis (trees) and gap of grasses. The soils were analyzed for physico-chemical parameters (organic matter and water contents, pH, C, N, Cr, Cu, Ni and Pb concentrations) and biological parameters (microbial and fungal biomass, respiration, metabolic quotient and coefficient of endogenous mineralization). The soil quality was evaluated through an integrated index, calculated taken into account all the investigated parameters. The results highlighted that soils under trees inside the urban park, with the highest amount of organic matter, showed higher microbial biomass and activity as compared to soils under grasses. The high concentration of Cu and Pb in these latter soils inhibited the microbial biomass and activity that were not exclusively affected by litter quality. Soil quality would seem to be strongly affected by the pedogenetic derivation and the management practices more than plant covers

Realizing caustics in acoustic fields

We present a method to realise a wide class of caustics in acoustic fields created by a set of phase holograms realized with metasurfaces. Given the desired caustic shape, we discuss how to identify the phase distribution along the metasurfaces and describe the calculations needed for determining the pressure field in the vicinity of the caustic. The results of this work can be used in realising acoustic traps controllable with acoustic metamaterials

Un-biodegradable and biodegradable plastic sheets modify the soil properties after six months since their applications

Nowadays, microplastics represent emergent pollutants in terrestrial ecosystems that exert impacts on soil properties, affecting key soil ecological functions. In agroecosystems, plastic mulching is one of the main sources of plastic residues in soils. The present research aimed to evaluate the effects of two types of plastic sheets (un-biodegradable and biodegradable) on soil abiotic (pH, water content, concentrations of organic and total carbon, and total nitrogen) and biotic (respiration, and activities of hydrolase, dehydrogenase, β-glucosidase and urease) properties, and on phytotoxicity (germination index of Sorghum saccharatum L. and Lepidium sativum L.). Results revealed that soil properties were mostly affected by exposure time to plastics rather than the kind (un-biodegradable and biodegradable) of plastics. After six months since mesocosm setting up, the presence of un-biodegradable plastic sheets significantly decreased soil pH, respiration and dehydrogenase activity and increased total and organic carbon concentrations, and toxicity highlighted by S. saccharatum L. Instead, the presence of biodegradable plastic sheets significantly decreased dehydrogenase activity and increased organic carbon concentrations. An overall temporal improvement of the investigated properties in soils covered by biodegradable plastic sheets occurred

SYNTHESIS OF alpha , omega - DIESTERS

The present invention relates to the transformation of alicyclic ketones with an alpha hydrogen to the corresponding alpha,omega diesters by the reaction with organic carbonates in the presence of cesium or potassium carbonates and of a phase-transfer agen