Calibration of a granular matrix sensor for suction measurements in partially saturated pyroclastic soil

Field monitoring of soil moisture and matrix suction is a useful tool for the implementation of a reliable early warning system against rainfall-induced landslide occurrence. Several test fields have been set up in Campania region (southern Italy), frequently affected by flow-like landslides involving pyroclastic soil cover. In particular, at the Mount Faito test site (Lattari Mountains, southeast of Naples), field matric suctions were measured over two years by conventional jet-fill tensiometers and granular matrix sensors (Watermark, Irrometer®) at different depths. Granular matrix sensor is a resistive device that is more and more spread in agriculture applications and that may also be used for geotechnical purposes thanks to a suitable calibration. In order to gain the calibration curve of the Watermark sensor, two small tip tensiometers (STT) and one High Capacity Tensiometer (HCT) were installed at the same depth of the Watermark sensor in the partially saturated pyroclastic soil sampled at the topsoil of the Mount Faito test site. Tests were carried out in the laboratory by performing drying and wetting phases on undisturbed soil sample. By coupling resistance measurements by Watermark and matrix suction provided by the reference tensiometers, it was possible to derive the non-linear relationship between these two quantities. The soil retention curve was also determined thanks to the installation in the soil sample of a decagon probe previously calibrated in the same pyroclastic soil

Water retention and shrinkage curves of weathered pyroclastic soil

The modelling of the triggering mechanism of rainfall-induced landslides in slopes covered by pyroclastic soil (as the area surrounding Mount Vesuvius in Campania, Italy) requires the hydraulic characterization of soil in unsaturated conditions in order to analyse the slope response to rainfalls. In previous studies carried out on Campanian pyroclastic soils, the volumetric soil changes due to suction changes have been disregarded, being them negligible in soils characterized by low plasticity and low clay contents. However, a more accurate determination of the water retention curve (WRC) in terms of volumetric water content requires a correct estimation of the total soil volume, which is affected by the soil stress-state. The proper approach would require the estimation of both WRC in terms of gravimetric water content and the shrinkage curve (SC). In the present study, a relation between void ratio and suction was determined for a pyroclastic soil sampled at Mount Faito in Southern Italy. Therefore, a correction of the volumetric water content was carried out resulting in updated water retention curves. Here, the matric suction was the only factor affecting the stress-state of the soil

A prototype for water content measurement in partially saturated soils

The paper presents the technological set-up and calibration of a system based on impedance spectroscopy for measuring water content in partially saturated soils. The technique adopted is relatively recent in geotechnical practice; it is used herein to characterize the electrical response of a soil specimen among two conducting electrodes upon application of an alternate voltage and the measurement of the current intensity resulting across the specimen, for frequency values in the range [500 Hz - 50 kHz]. The complex impedance of the soil specimen is due to both resistance, i.e. opposition to current, and reactance, i.e. tendency of the system to yield and retrieve energy, and it depends on the specimen water content. An on-purpose experimental plan has been conceived and is presented herein, aimed at building a calibration function for deriving the water content in pyroclastic soils from the impedance measurements. Preliminary results reveal an adequate level of repeatability of the measurements and suggest the existence of a monotonic correlation between the impedance modulus and the gravimetric water content

Experimental and numerical investigations of a river embankment model under transient seepage conditions

The evaluation of riverbank stability often represents an underrated problem in engineering practice, but is also a topical geotechnical research issue. In fact, it is certainly true that soil water content and pore water pressure distributions in the riverbank materials vary with time, due to the changeable effects of hydrometric and climatic boundary conditions, strongly influencing the bank stability conditions. Nonetheless, the assessment of hydraulic and mechanical behavior of embankments are currently performed under the simplified hypothesis of steady\u2010state seepage, generally neglecting the unsaturated soil related issues. In this paper, a comprehensive procedure for properly defining the key aspects of the problem is presented and, in particular, the soil characterization in partially saturated conditions of a suitably compacted mixture of sand and finer material, typical of flood embankments of the main river Po tributaries (Italy), is reported. The laboratory results have then been considered for modelling the embankment performance under transient seepage and following a set of possible hydrometric peaks. The outcome of the present contribution may provide meaningful geotechnical insights, for practitioners and researchers, in the flood risk assessment of river embankments

E-cadherin engagement stimulates proliferation via Rac1

E-cadherin has been linked to the suppression of tumor growth and the inhibition of cell proliferation in culture. We observed that progressively decreasing the seeding density of normal rat kidney-52E (NRK- 52E) or MCF-10A epithelial cells from confluence, indeed, released cells from growth arrest. Unexpectedly, a further decrease in seeding density so that cells were isolated from neighboring cells decreased proliferation. Experiments using microengineered substrates showed that E-cadherin engagement stimulated the peak in proliferation at intermediate seeding densities, and that the proliferation arrest at high densities did not involve E-cadherin, but rather resulted from a crowding-dependent decrease in cell spreading against the underlying substrate. Rac1 activity, which was induced by E-cadherin engagement specifically at intermediate seeding densities, was required for the cadherin-stimulated proliferation, and the control of Rac1 activation by E-cadherin was mediated by p120- catenin. Together, these findings demonstrate a stimulatory role for E-cadherin in proliferative regulation, and identify a simple mechanism by which cell–cell contact may trigger or inhibit epithelial cell proliferation in different settings

The effect of temperature on Triclosan and Lead exposed mussels

Interest on the effects of emerging contaminants over aquatic organisms has increased in the last years. Nonetheless, the toxic action of classical natural and anthropogenically-driven metals has also to be monitored, especially because they reflect real environmental situations. For that, in the present study we focused on the effects on the marine mussel Mytilus galloprovincialis of the personal care product Triclosan (TCS) and Lead (Pb), as toxic metal, under separate and co-exposure situations at environmentally relevant concentrations: TCS (1 μg/L) and Pb (50 μg/L). The consideration of an additional factor such as an increase in ambient temperature was also included to provide a forecasted scenario of climate change: from the ambient temperature at actual conditions (17 °C) to a predicted warming situation (22 °C). Water chemical characterization and some physical properties and bioaccumulation of TCS and Pb in mussels at the end of the experiment (28 days) was considered. The parameters followed up comprise the energy related system production (electron transport system) and glycogen and protein reserves. Antioxidant enzymatic defences towards reactive oxygen species (ROS) and the consequences of ROS damage over endogenous lipids (LPO) and proteins (PC). Overall the results suggested only particular responses to chemical exposures at 17 °C whereas at 22 °C the detoxification machinery was set up and this prevented the occurrence of LPO. Nonetheless, PC formation occurred under Pb and TCS + Pb co-exposure at the highest temperature. Due to the complexity of the study: 4 chemical conditions, 2 temperatures and 10 biomarkers considered, a principal component ordination (PCO) analysis was included. The results of this integrative analysis confirmed a clear effect of the temperature, more responsiveness to drugs at 22 °C and in all likelihood due to Pb presence.publishe

Osteopontin expression in healing wounds of horses and in human keloids

REASONS FOR PERFORMING STUDY: Convincing evidence shows that persistent or excessive expression of osteopontin (OPN) is linked to fibroproliferation of various organs in laboratory animals and in man, such that its downregulation is a logical therapeutic objective. OBJECTIVES: To investigate OPN expression in an equine model of wound healing and in clinical specimens of equine exuberant granulation tissue and human keloids in an effort to better understand the contribution of this protein to inflammation-associated skin fibrosis. STUDY DESIGN: Description of gene and protein expression in an experimental equine model of wound healing and clinical specimens in horse and man. METHODS: Osteopontin gene expression was evaluated by quantitative PCR, while protein expression was investigated by means of immunohistochemical staining. RESULTS: Quantitative PCR showed that the OPN gene is expressed in normal intact skin of horses and continues to be expressed during the wound-healing process. An increase in gene expression was observed throughout the phases of wound healing, with a final decrease at wound closure. The protein was not detected in normal skin. Keratinocytes in wound-edge samples did not express the protein, whereas dermal immunoreactivity was confined to inflammatory cells. Healed wounds were devoid of staining. Equine exuberant granulation tissue showed immunoreactivity of the surrounding epidermis, infiltrating neutrophils, mononuclear cells, endothelial cells and fibroblasts. Human keloids showed OPN immunoreactivity throughout the epidermis as well as in mononuclear cells and scattered fibroblasts. CONCLUSIONS: Immunohistochemical data show a different pattern of expression between normally healing and fibrotic wounds (exuberant granulation tissue and keloids), thus suggesting a role in fibroproliferation in horses and man

Folding mechanisms steer the amyloid fibril formation propensity of highly homologous proteins

Significant advances in the understanding of the molecular determinants of fibrillogenesis can be expected from comparative studies of the aggregation propensities of proteins with highly homologous structures but different folding pathways. Here, we fully characterize, by means of stopped-flow, T-jump, CD and DSC experiments, the unfolding mechanisms of three highly homologous proteins, zinc binding Ros87 and Ml153-149 and zinc-lacking Ml452-151. The results indicate that the three proteins significantly differ in terms of stability and (un)folding mechanisms. Particularly, Ros87 and Ml153-149 appear to be much more stable to guanidine denaturation and are characterized by folding mechanisms including the presence of an intermediate. On the other hand, metal lacking Ml452-151 folds according to a classic two-state model. Successively, we have monitored the capabilities of Ros87, Ml452-151 and Ml153-149 to form amyloid fibrils under native conditions. Particularly, we show, by CD, fluorescence, DLS, TEM and SEM experiments, that after 168 hours, amyloid formation of Ros87 has started, while Ml153-149 has formed only amorphous aggregates and Ml452-151 is still monomeric in solution. This study shows how metal binding can influence protein folding pathways and thereby control conformational accessibility to aggregation-prone states, which in turn changes aggregation kinetics, shedding light on the role of metal ions in the development of protein deposition diseases

Investigating the properties of TBA variants with twin thrombin binding domains

In this paper, we report studies concerning thrombin binding aptamer (TBA) dimeric derivatives in which the 3'-ends of two TBA sequences have been joined by means of linkers containing adenosine or thymidine residues and/or a glycerol moiety. CD and electrophoretic investigations indicate that all modified aptamers are able to form G-quadruplex domains resembling that of the parent TBA structure. However, isothermal titration calorimetry measurements of the aptamer/thrombin interaction point to different affinities to the target protein, depending on the type of linker. Consistently, the best ligands for thrombin show anticoagulant activities higher than TBA. Interestingly, two dimeric aptamers with the most promising properties also show far higher resistances in biological environment than TBA