Hydrogeology and hydrogeochemistry of an alkaline volcanic area: the NE Mt. Meru slope (East African Rift – Northern Tanzania)

Abstract. The objective of this study is to analyze the geochemical conditions associated with the presence of fluoride (F−) in the groundwater of an area of Northern Tanzania. The studied aquifers are composed of volcanic rocks such as phonolitic and nephelinitic lavas, basalts, lahars of various ages and mantling ash. Sedimentary rocks consisting of fine-grained alluvial and lacustrine deposits occur as well. Samples collected from springs, borehole and surface water, during two monitoring surveys, were analyzed for the various physico-chemical and isotopic parameters. The geochemical composition of water is typically sodium bicarbonate. High values of F− (up to 68 mg l−1) were recorded. The highest values of fluoride agreed with the highest values of pH, sodium and bicarbonate. Dissolution of major ions, exchange processes and precipitation of Ca2+ from super-saturated solutions joined with the local permeability and hydraulic gradients, control the fluoride mobilization and the contamination of the area

Defect-Correlated Vickers Microhardness of Al-Si-Mg Alloy Manufactured by Laser Powder Bed Fusion with Post-process Heat Treatments

Laser powder bed fusion is an additive manufacturing process characterized by different advantages like the manufacture of samples with complex geometry without the use of tools and/or molds. Generally, the manufactured samples are characterized by high tensile strengths which, however, can be affected by the presence of defects due to the unoptimized process parameters. In a large applications field, a low density of the as-built AlSi10Mg samples is a very important parameter to considered, e.g., due to both the loss of the tensile strengths correlated with a premature failure of the samples and the increase in time and costs associated with the manufacturing process. In addition, different post-process heat treatments can increase these effects leading to an ineffective manufacturing process. In this scenario, the present work shows the analysis of spherical and lack-of-fusion pores induced by the laser powder bed fusion process on the AlSi10Mg samples and their variations after different heat treatments (direct aging and T6). At the same time, the influence of pores on the Vickers microhardness and the tensile properties has been studied in the same AlSi10Mg samples (bars and billets) that were printed with single- and double-laser machine setup. Different process parameters were also analyzed and compared. The study was supported by the microstructural and pore analysis performed by optical microscopy along the XZ plane (build direction) and the XY plane. Finally, the greatest effects of pores were observed on the Vickers microhardness values; in fact, two different relationships between microhardness and density variation are discussed. The T6 heat treatment leads to a rounding of the pores already formed in the as-built samples and to a formation of new small pores. Graphical Abstract: [Figure not available: see fulltext.

Attention and cognitive load modulate motor resonance during action observation

Observation of others\u2019 actions evokes a motor resonant (MR) response, in the parieto-frontal Action Observation Network (AON, comprising BA40, BA6, BA4). In order to investigate the effect of cognitive processes on the AON we manipulated attention and cognitive load during central and peripheral observation of hand grasping actions with three experiments. Motor Evoked Potentials (MEPs) were elicited in the opponent of the thumb (OP) and abductor of the little finger (ADM) by Transcranial Magnetic Stimulation (TMS) of the primary motor cortex. First, we investigated the role of selective attention by asking subjects to focus their attention on the thumb of the moving hand in central vision. A selective facilitation of OP MEPs was recorded, without the expected ADM MEPs modulation. Second, a \u201ccovert attention\u201d paradigm was used to investigate the role of attention in peripheral vision. Surprisingly, MEP modulation was virtually abolished. In the third experiment we tested the hypothesis that the higher cognitive load introduced by the covert attention instruction had interfered with MR. We allowed subjects to view the action before its peripheral presentation with covert attention, thereby decreasing the cognitive effort necessary to decode the grasping action. The accuracy of motor resonant response was restored

The effect of a new geometric bicycle saddle on the genital-perineal vascular perfusion of female cyclists

Purpose. — Female cyclists undergo a perineal compression of the pudendal nerve and genitalperineal area, with underexplored effects on genital injuries and sexual dysfunctions. This study tests the effects of a new geometric bicycle saddle (SMP) on perineal compression, blood perfusion, genital sensation and sexual function. Methods. — Thirty-three professional female athletes were monitored when using both the new saddle and a traditional professional saddle, in a randomized order. Short-term effects are estimated by measuring the partial pressure of vagina transcutaneous oxygen (PtcO2) before using the saddle, after 10 minutes of static sitting, after riding 20 minutes. Long-term effects are estimated by measuring athletes Female Sexual Distress Scale (FSDS) before using the new saddle and after 6 months using it. Results. — From an initial average of 70 mmHg, PtcO2 decreases by 30 mmHg after riding on a traditional saddle, 10 mmHg on the new saddle (respectively 20 and 7 after just sitting). When using the traditional saddle all FSDS scores are well over the 12 ‘‘normality’’ threshold, with an average of 41, while after using the new saddle the average falls to 12. All differences between the saddles are strongly significant: paired t-tests > 6; P < 0.001; 95% confidence intervals respectively 13 ± 3 mmHg after sitting, 20 ± 3 mmHg after riding, 29 ± 2 FSDS scores. Conclusion. — Traditional saddles have strong negative effects on the vascular perfusion of the vulva, with possible consequences on female sexual functions. The SMP saddle reduces the compression on the pelvic floor and can help reducing the incidence of urogenital pathologies for female cyclists

Repairing 2024 Aluminum Alloy via Electrospark Deposition Process: A Feasibility Study

The electrospark deposition (ESD) technique has been studied as a potential method to repair locally damaged 2024 rolled sheets supplied in natural-aged (T4) and artificial-aged (T6) conditions. The 2024-T4 and 2024-T6 tensile samples were first notched, and then the notches were filled (repaired) by ESD with the same aluminum alloy. The effect of process parameters on the microstructure of the filling material and the substrate properties was studied by optical and scanning electron microscopy. Tensile and hardness tests were performed. The tensile test showed that T4 and T6 as-repaired specimens had low tensile properties, which was due to defectiveness and residual stress caused by high cooling rate during reparation. However, the as-repaired specimens were heat-treated at either 135°C or 190°C to improve the mechanical properties. A better yield strength was observed for the T4 heat-treated alloy. The ductility and ultimate tensile strength did not change, being mainly affected by voids and microcracks

Leptospira fainei detected in testicles and epididymis of wild boar (Sus scrofa)

Leptospirosis is a re-emerging and worldwide diffused zoonosis. Recently, the high importance of their epidemiology was explained by the intermediate Leptospira strains. Among these strains, Leptospira fainei was the first intermediate strain detected in domestic and wild swine. Wild boars (Sus scrofa) are well known as a reservoir, as well as all swine, for pathogenic Leptospira, but very little information is available concerning intermediate Leptospira infection. The investigation aim was to evaluate if intermediate Leptospira can infect the reproductive systems of wild boars hunted in the Tuscany region (Italy), as previously demonstrated for pathogenic ones. The reproductive system tissue (testicles, epididymides, uteri), and placentas and fetuses, were collected from 200 regularly hunted animals. Bacteriological examination and real-time PCR were performed to detect intermediate Leptospira DNA. Unfortunately, no isolates were obtained. Using real-time PCR, in six (3%) male organs (both testicles and epididymis), intermediate Leptospira DNA was found. The amplification of the 16S rRNA gene identified that all DNA obtained belong to Leptospira fainei. The results of this investigation highlighted for the first time the localization of Leptospira fainei in the male wild boar reproductive system, opening up a new avenue to further investigate

Persistent topology for natural data analysis - A survey

Natural data offer a hard challenge to data analysis. One set of tools is being developed by several teams to face this difficult task: Persistent topology. After a brief introduction to this theory, some applications to the analysis and classification of cells, lesions, music pieces, gait, oil and gas reservoirs, cyclones, galaxies, bones, brain connections, languages, handwritten and gestured letters are shown

Static and dynamic precipitation phenomena in laser powder bed-fused Ti6Al4V alloy

The present paper investigates static and dynamic precipitation phenomena in the Ti6Al4V alloy produced via laser-powder bed fusion, solubilized at 1050 degrees C and aged in the range of 450-650 degrees C. In relation to the distance from the platform on which the samples are disposed during the solution heat treatment, the microstructure varies from alpha-laths to alpha-colonies arranged in a Widmanstatten structure. The aging heat treatment at 450 degrees C promotes the formation of stacking faults into alpha-laths and the precipitation of alpha(2)-Ti3Al phases. SEM and TEM observations reveal that the density of precipitates increases after aging at 500 degrees C, while coarsening of the alpha-phase occurs only after aging heat treatment at 600 degrees C. Vickers microhardness measurements reveal different peak-aging conditions and show that the alloy is unstable at high temperatures (T &gt; 450 degrees C), both in the case of static and dynamic precipitation phenomena. Only the aging profile at 450 degrees C shows a constant trend of Vickers microhardness after 4 h of treatment