Multi-scale analysis on soil improved by alkali activated fly ashes

The development of soil treatment techniques using alkali-activated binders is a relevant issue since the increasing interest into the use of new binders as an alternative solution for geotechnical engineering applications, such as soil improvement. Alkali activated binders are formed by alkaline activation of an aluminosilicate source, containing precursor materials like fly ash, silica fume, steel sludge, which chemically react with an alkaline solution (i.e. sodium hydroxide, sodium silicate) forming a three-dimensional aluminosilicate gel with cementitious properties (Duxon et al. 2007, Provis and van Deventer 2014, Davidovits 1991, Xu and van Deventer 2000, Shi et al. 2006). Recycling of waste materials such as by-product from industrial process to synthesize a new binder favors a closed loop of material use, which minimizes the generation of waste and reduces the costs of production. Alkali activated binders represent a viable sustainable alternative to the use of ordinary binders for soil improvement (Vitale et al. 2017a; Vitale et al. 2017b). In the present study, an insight into the mechanical improvement induced by alkali-activated binders based on the activation of two different type of fly ashes on a clayey soil has been presented. An experimental multiscale analysis on chemo-physical evolution of the systems and its influence on microstructural features of treated soil has been developed highlighting the link between alkaline activation processes and macroscopic evolution of soil properties. Mechanical tests have been performed and interpreted taking into account the chemo-physical evolution of alkali activated fly ashes. Effects of binder content and curing time have been also considered. Addition of alkali-activated binders increases shear strength of the treated samples since the very short term. A reduction of compressibility and an increase of yield stress of treated samples have been also detected, whose extent depends on the curing time and on the binder content. Macroscopic behaviour of treated soil has been linked to the experimental evidences at microscale. Mineralogical and fabric changes induced by alkali-activated binders have been monitored over time by means of X ray diffraction (XRD), thermogravimetric analysis, 29Si NMR spectroscopy and Mercury Intrusion Porosimetry (MIP). Test results showed a high reactivity of alkali activated fly ashes as alumino-silicate source promoting precipitation of new mineralogical phase forming chains and networks with cementitious properties, responsible of the mechanical improvement of the treated soil. The efficiency of treatment has been also highlighted by comparing the mechanical performance induced by alkali-activated binder with the one promoted by ordinary Portland cement. Duxon P., Fernàndez-Jiménez A., Provis J.L., Lukey G.C., Palomo A., van Deventer J.S.J (2007). Geopolymer Technology: The Current State of the Art. Journal of Materials Science 42, 9, 2917-2933. Provis J.L., van Deventer J.S.J (2014). eds. Alkali Activated Materials. Vol.13. RILEM State of the Art Reports. Dordrecht: Springer Netherlands. Davidovits J. (1991). Geopolymers: inorganic polymeric new materials. J Therm Anal, 37,1633-1656. Xu H., van Deventer J.S.J. (2000). The geopolymerisation of alumina-silicate minerals. Int J Miner Process, 59, 247-266. Shi C., Krivenko P.V., Roy D.M. (2006). Alkali-activated Cements and Concretes. Abington, UK, Taylor and Francis. Vitale E., Coudert E., Deneele D., Paris M., Russo G. (2017a). Multiscale analysis on a kaolin improved by an alkali-activated binder. Proceedings of the 2nd Symposium on Coupled Phenomena in Environmental Geotechnics (CPEG2), Leeds, UK. Vitale E., Russo G., Dell’Agli G., Ferone C., Bartolomeo C. (2017b). Mechanical behaviour of soil improved by alkali activated binders. Environments, 4, 80, doi:10.3390/environments4040080

Seroprevalence of and risk factors for Leishmania seropositivity in a sample population of Western Sicily (Italy)

Background: Leishmania is a vector-borne parasite responsible for significant morbidity and mortality worldwide. The aim of this study was to assess the prevalence of and risk factors for Leishmania infantum seropositivity in a sample of Sicilian population.Methods: A total of 260 subjects were interviewed using a standardized questionnaire and requested for an venous blood sample.Results: Overall, 36 subjects (13.8%) were seropositive against L. infantum with a statistically significant higher prevalence of positivity in older subjects (p=0.04). After adjustment for age, a higher risk for Leishmania seropositivity was found in subjects who had pets living outdoors and untreated with anti-pests, and in those who were current smokers (adj-OR = 2.95 and adj-OR = 3.11, respectively; p < 0.05).Conclusions: Our data confirm that Leishmania infections among Sicilian citizens can be considered relatively frequent, suggesting that a percentage of Leishmania seropositivity can be probably attributed to exposure to both old and new risk factors

Influence of pore water chemistry on hydaulic conductivity of kaolinite suspensions

The role of pore water chemistry on particle aggregation and soil formation during sedimentation process has been investigated for a kaolinite clay suspensions. The modification of surfaces charge properties of clay minerals induced by different pore water chemistry rules the particles arrangement. As a consequence, at volume scale the sedimentation behaviour and in turn the physical, mechanical and hydraulic behaviour of the formed soil skeleton are changed. Sedimentation tests on several suspensions showed the influence of different aggregation on settling and self-weight consolidation stages. Hydraulic conductivity of kaolin suspensions has been estimated from the settling velocity recorded in sedimentation tests. Test results showed the relevant dependency of the hydraulic conductivity of the clay suspensions on the particle arrangement induced by the pore water chemistry

Microstructural evolution and mechanical behaviour of alkali activated fly ash binder treated clay

This work focuses on the use of alkali activated fly ash-based binder to enhance engineering characteristics of soft clay-rich soils and as a substitute to standard stabilisers (e.g., lime or cement). Especially, it examines the microstructural evolution of a calcium-rich fly ash from coal combustion-based binder activated by a sodium-based alkaline solution. To this end, the processes generating the microstructure and the evolution of the pore network over time are investigated. A second point addressed by this study is how the presence of kaolin particles affects the microstructural features of the binder. The microstructure has therefore been investigated by considering the binder alone and the binder mixed with kaolin. The effects of microstructural evolution have been observed at macroscopic level by means of one-dimensional compression tests. The combination of completing techniques has been used including Optical microscopy, Scanning Electron Microscopy and Mercury Intrusion Porosimetry in order to gain an overview of the complex pore structure. Microstructural changes occur around calcium-containing phases derived from fly ash which are the reactive phases of the system. Namely, the dissolution of calcium-rich grains leads to the formation of new compounds that first cover the grain surfaces and then further grow into the available space. Furthermore, the evolution of the pore network over time is characterized by a progressive filling of capillary pores by new compounds while small nanometric pores are being formed and associated with the newly formed silicate-calcium chains. Similar tendencies are observed when the binder is mixed with the soil although the general porosity is lesser due to the filling of pores by small-sized kaolinite platelets. Experimental evidences at microscale level have been linked to the macroscopic behaviour of treated soil

Effects of an intervention to prevent the bullying in first-grade secondary schools of Palermo, Italy: the BIAS study

Background: Bullying is one of the most common expressions of violence in the peer context during school years. This study investigates the prevalence of bullying and the short-term effects on students’ bullying perceptions of a preventive intervention conducted among teachers of first-grade secondary schools in Palermo, Sicily (Italy). Methods: Between the 2017/2018 and 2018/2019 school years, a pre-post intervention study was conducted among nine school institutions, sampled and categorized by neighbourhood socioeconomic index. A questionnaire investigating physical, verbal, and indirect bullying, the role of observers, prosociality, and resiliency in bullying was administered before and after intervention with formative cascade training of the teachers of the selected classes. Three different methods (sentinel questions, the five-question method, the ‘score of seven’ method) were used to detect the baseline level of bullying. Results: A total of 402 students participated in the study (72.7% response rate). A decrease in the number of bullying episodes after the intervention was reported by the students in all types of bullying explored (physical, verbal, and indirect bullying, observers, resiliency, and prosociality), with all three methods. In particular, a statistically significant decrease in all the bullying areas investigated (except for resiliency) was reported for students attending schools of an intermediate socioeconomic level. Conclusions: Even if many school-based interventions have been implemented to reduce school bullying throughout the world, this is one of the first conducted in Europe and it assesses the effectiveness among students of an antibullying intervention tailored for teachers. The encouraging results in reducing the number of bullying episodes together with the low cost in terms of human and economic resources could suggest an extension of this research on a regional/national scale

Risk of classical Kaposi sarcoma by plasma levels of Epstein-Barr virus antibodies, sCD26, sCD23 and sCD30

<p>Abstract</p> <p>Background</p> <p>To clarify the immunological alterations leading to classical Kaposi sarcoma (cKS) among people infected with KS-associated herpesvirus (KSHV).</p> <p>Methods</p> <p>In a population-based study of 119 cKS cases, 105 KSHV-seropositive controls, and 155 KSHV-seronegative controls, we quantified plasma soluble cluster of differentiation (sCD) levels and antibodies against Epstein-Barr virus nuclear antigen-1 (anti-EBNA-1) and viral capsid antigen (anti-VCA). Differences between groups in prevalence of low-tertile anti-EBNA-1 and high-tertile anti-VCA were compared by logistic regression. Continuous levels between groups and by presence of cKS co-factors among controls were compared by linear regression and Mann-Whitney-Wilcoxon methods.</p> <p>Results</p> <p>Comparisons of cKS cases to seropositive controls and of seropositive to seronegative controls revealed no significant differences. However, controls with known cKS cofactors (male sex, nonsmoking, diabetes and cortisone use) had significantly lower levels of anti-EBNA (<it>P </it>= 0.0001 - 0.07) and anti-VCA (<it>P </it>= 0.0001 - 0.03). Levels of sCD26 were significantly lower for male and non-smoking controls (<it>P</it>_adj≤ 0.03), and they were marginally lower with older age and cortisone use (<it>P</it>_adj≤ 0.09).</p> <p>Conclusions</p> <p>Anti-EBV and sCD26 levels were associated with cofactors for cKS, but they did not differ between cKS cases and matched controls. Novel approaches and broader panels of assays are needed to investigate immunological contributions to cKS.</p

Predictors of Central Compartment Involvement in Patients with Positive Lateral Cervical Lymph Nodes According to Clinical and/or Ultrasound Evaluation

Lymph node neck metastases are frequent in papillary thyroid carcinoma (PTC). Current guidelines state, on a weak level of evidence, that level VI dissection is mandatory in the presence of latero-cervical metastases. The aim of our study is to evaluate predictive factors for the absence of level VI involvement despite the presence of metastases to the lateral cervical stations in PTC. Eighty-eight patients operated for PTC with level II-V metastases were retrospectively enrolled in the study. Demographics, thyroid function, autoimmunity, nodule size and site, cancer variant, multifocality, Bethesda and EU-TIRADS, number of central and lateral lymph nodes removed, number of positive lymph nodes and outcome were recorded. At univariate analysis, PTC location and number of positive lateral lymph nodes were risk criteria for failure to cure. ROC curves demonstrated the association of the number of positive lateral lymph nodes and failure to cure. On multivariate analysis, the protective factors were PTC located in lobe center and number of positive lateral lymph nodes &lt; 4. Kaplan-Meier curves confirmed the absence of central lymph nodes as a positive prognostic factor. In the selected cases, Central Neck Dissection (CND) could be avoided even in the presence of positive Lateralcervical Lymph Nodes (LLN+)

Capillary barriers during rainfall events in pyroclastic deposits of the Vesuvian area

In the present paper, the capillary barrier formation at the interface between soil layers, which is characterized by textural discontinuities, has been analyzed. This mechanism has been investigated by means of a finite element model of a two-layer soil stratification. The two considered formations, belonging to the pyroclastic succession of the “Pomici di Base” Plinian eruption (22 ka, Santacroce et al., 2008) of the Somma–Vesuvius volcano, are affected by shallow instability phenomena likely caused by progressive saturation during the rainfall events. This mechanism could be compatible with the formation of capillary barriers at the interface between layers of different grain size distributions during infiltration. One-dimensional infiltration into the stratified soil was parametrically simulated considering rainfall events of increasing intensity and duration. The variations in the suction and degree of saturation over time allowed for the evaluation of stability variations in the layers, which were assumed as part of stratified unsaturated infinite slopes

Residues of 165 pesticides in citrus fruits using LC-MS/MS: a study of the pesticides distribution from the peel to the pulp

Abstract A sensitive LC–ESI-MS/MS method was developed for the determination of 165 pesticides in 50 citrus fruit samples collected in Sicily. Moreover, an evaluation of pesticides levels in the citrus layers (peel, albedo, and pulp) was carried out. The method presented acceptable trueness, precision, and linearity with LOQ of 5 μg/kg. The results obtained showed a high frequency of fungicides class pesticides in all the citrus samples examined (&gt;95%) with the highest concentrations in the peel (4468 µg/Kg). A significant difference of concentrations was found between the layers of the citrus fruits analysed (p &lt; 0.05). In particular, the peel and albedo present higher pesticides significantly higher than the pulp. Our findings confirming the widespread use of these substances in citrus cultivation and suggesting the importance of pesticides analysis in all the citrus fruit layers separately, considering the different interactions between the physicochemical characteristics of the matrices and the pesticides

2-Pentadecyl-2-oxazoline ameliorates memory impairment and depression-like behaviour in neuropathic mice: possible role of adrenergic alpha2- and H3 histamine autoreceptors

Neuropathic pain (NP) remains an untreatable disease due to the complex pathophysiology that involves the whole pain neuraxis including the forebrain. Sensory dysfunctions such as allodynia and hyperalgesia are only part of the symptoms associated with neuropathic pain that extend to memory and affectivity deficits. The development of multi-target molecules might be a promising therapeutic strategy against the symptoms associated with NP. 2-pentadecyl-2-oxazoline (PEA-OXA) is a plant-derived agent, which has shown effectiveness against chronic pain and associated neuropsychiatric disorders. The molecular mechanisms by which PEA-OXA exerts its effects are, however, only partially known. In the current study, we show that PEA-OXA, besides being an alpha2 adrenergic receptor antagonist, also acts as a modulator at histamine H3 receptors, and report data on its effects on sensory, affective and cognitive symptoms associated with the spared nerve injury (SNI) model of neuropathic pain in mice. Treatment for 14&nbsp;days with PEA-OXA after the onset of the symptoms associated with neuropathic pain resulted in the following effects: (i) allodynia was decreased; (ii) affective/cognitive impairment associated with SNI (depression, spatial, and working memories) was counteracted; (iii) long-term potentiation in vivo in the lateral entorhinal cortex-dentate gyrus (perforant pathway, LPP) was ameliorated, (iv) hippocampal glutamate, GABA, histamine, norepinephrine and dopamine level alterations after peripheral nerve injury were reversed, (v) expression level of the TH positive neurons in the Locus Coeruleus were normalized. Thus, a 16-day treatment with PEA-OXA alleviates the sensory, emotional, cognitive, electrophysiological and neurochemical alterations associated with SNI-induced neuropathic pain