Nucleation Induced Undulative Instability in Thin Films of nCB Liquid Crystals

A surface instability is reported in thin nematic films of 5CB and 8CB, occurring near the nematic--isotropic phase transition. Although this instability leads to patterns reminiscent of spinodal dewetting, we show that it is actually based on a nucleation mechanism. Its characteristic wavelength does not depend markedly on film thickness, but strongly on the heating rate.Comment: 4 pages, 5 figure

Effect of homegarden and parkland agroforestry practices in Ethiopia on selected soil properties

Ethiopian agricultural lands are fragile due to inherent unfavourable soil properties, over-exploitation, mismanagement (deforestation, over-grazing and inappropriate land use systems) and harsh weather conditions. These factors are worsened by changing climatic conditions, leading to significant problems in terms of soil erosion and loss of soil fertility. The consequences of such processes can be detected at the economic (agricultural production is currently being jeopardized) and biological (risks of biodiversity loss and habitat fragmentation) levels. However, the use of tree/shrub species in various agroforestry practices can increase soil nutrient supply through nitrogen fixation, improve soil structure, reduce soil erosion and nutrient losses. A study was carried out in the Amhara region, Ethiopia to evaluate the effect of homegarden and parkland agroforestry practices on selected soil chemical properties. Soil samples were taken from 20x20m square plots established in homegarden agroforestry and adjacent agricultural land without trees (control). In parkland agroforestry practice, two dominant tree species in each of the five villages were chosen. Soil samples were taken from the tree at the midpoint of the canopy projection, at 0-15 and 15-30 cm depths. The collected soil samples were air-dried, homogenized and passed through a 2 mm sieve for subsequent soil chemical analysis. The results indicated that all soil chemical properties except total nitrogen were significantly (P ≤ 0.05) affected by the agroforestry practices. Higher soil organic carbon, organic matter, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry practice, while the lowest values were recorded in without-tree fields (control). All soil chemical properties except soil pH decreased as the soil depth increased. Higher value of organic carbon, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry likely because of a higher proportion of deep-rooted tree/shrub species and species belonging to the legume functional group. Therefore, the homegarden agroforestry practice can be used as an ecologically friendly and sustainable alternative to maintaining soil fertility

Mitigating crop yield losses through weed diversity

International audienc

Competitive surface colonization of antibacterial and bioactive materials doped with strontium and/or silver ions

Nowadays, there is a large amount of research aimed at improving the multifunctional behavior of the biomaterials for bone contact, including the concomitant ability to induce apatite formation (bioactivity), fast and effective osteoblasts colonization, and antibacterial activity. The aim of this study is to develop antibacterial and bioactive surfaces (Ti6Al4V alloy and a silica-based bioactive glass) by chemical doping with strontium and/or silver ions. The surfaces were characterized by Scanning Electron Microscopy equipped with Energy Dispersive X ray Spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and Transmission Electron Microscopy (TEM). To better focus on the cells–bacteria competition for the implant surface, in addition to the standard assays for the evaluation of the bacteria adhesion (ISO22196) and for single-cell cultures or biofilm formation, an innovative set of co-cultures of cells and bacteria is here proposed to simulate a competitive surface colonization. The results suggest that all the bioactive tested materials were cytocompatible toward the bone progenitor cells representative for the self-healing process, and that the doped ones were effective in reducing the surface colonization from a pathogenic drug-resistant strain of Staphylococcus aureus. The co-cultures experiments demonstrated that the doped surfaces were able to protect the adhered osteoblasts from the bacteria colonization as well as prevent the infection prior to the surface colonization by the osteoblasts

Albumin and fibronectin adsorption on treated titanium surfaces for osseointegration: An advanced investigation

Protein adsorption has a central role in the outcome of implants. However, there is no consensus about the impact of the different surface properties on the material-protein interactions. Here, the adsorption of albumin and fibmnectin in near-physiological concentration is investigated on three differently treated titanium-based surfaces and compared after a thorough characterization. The different titanium surfaces have very different surface properties, in particular regarding roughness, oxide porosity, wettability, surface energy, and zeta potential, which are all known to deeply affect protein adsorption. By merging several characterization techniques, some conventional and some innovative, it was possible to discriminate the effect of surface properties on different aspects of protein adsorption. Despite forming a continuous layer on all samples, the amount of proteins bound to the surface is mainly due to surface roughness and topography, which can overcome the effect of wettability and surface energy. On the other hand, the secondary structure of albumin and fibmnectin and their orientation are determined by the hydroxyl groups exposed on the surfaces, depending on their surface concentration and acidic reactivity in the former, and the surface zeta potential in the latter

Optimization of the appearance quality in CO2 processed ready-to-eat carrots through image analysis

A high-pressure CO2 process applied to ready-to-eat food products guarantees an increase of both their microbial safety and shelf-life. However, the treatment often produces unwanted changes in the visual appearance of products depending on the adopted process conditions. Accordingly, the alteration of the visual appearance influences consumers’ perception and acceptability. This study aims at identifying the optimal treatment conditions in terms of visual appearance by using an artificial vision system. The developed methodology was applied to fresh-cut carrots (Daucus carota) as the test product. The results showed that carrots packaged in 100% CO2 and subsequently treated at 6 MPa and 40◦C for 15 min maintained an appearance similar to the fresh product for up to 7 days of storage at 4◦C. Mild appearance changes were identified at 7 and 14 days of storage in the processed products. Microbiological analysis performed on the optimal treatment condition showed the microbiological stability of the samples up to 14 days of storage at 4◦C. The artificial vision system, successfully applied to the CO2 pasteurization process, can easily be applied to any food process involving changes in the appearance of any food product