6,466 research outputs found

    The structure of the plasma sheet-lobe boundary in the Earth's magnetotail

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    The structure of the magnetotail plasma sheet-plasma lobe boundary was studied by observing the properties of tailward flowing O+ ion beams, detected by the ISEE 2 plasma experiment inside the boundary during three time periods. The computed value of the north-south electric field component as well as the O+ parameters are shown to change at the boundary. The results are related to other observations made in this region. The O+ parameters and the Ez component behavior are shown to be consistent with that expected from the topology of the electric field lines in the tail as mapped from the ionosphere

    GPS-based CERN-LNGS time link for Borexino

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    We describe the design, the equipment, and the calibration of a new GPS based time link between CERN and the Borexino experiment at the Gran Sasso Laboratory in Italy. This system has been installed and operated in Borexino since March 2012, and used for a precise measurement of CNGS muon neutrinos speed in May 2012. The result of the measurement will be reported in a different letter.Comment: 13 pages, 11 figure

    Literature review on the potential of urban waste for the fertilization of urban agriculture: A closer look at the metropolitan area of Barcelona

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    Urban agriculture (UA) activities are increasing in popularity and importance due to greater food demands and reductions in agricultural land, also advocating for greater local food supply and security as well as the social and community cohesion perspective. This activity also has the potential to enhance the circularity of urban flows, repurposing nutrients from waste sources, increasing their self-sufficiency, reducing nutrient loss into the environment, and avoiding environmental cost of nutrient extraction and synthetization.The present work is aimed at defining recovery technologies outlined in the literature to obtain relevant nutrients such as N and P from waste sources in urban areas. Through literature research tools, the waste sources were defined, differentiating two main groups: (1) food, organic, biowaste and (2) wastewater. Up to 7 recovery strategies were identified for food, organic, and biowaste sources, while 11 strategies were defined for wastewater, mainly focusing on the recovery of N and P, which are applicable in UA in different forms.The potential of the recovered nutrients to cover existing and prospective UA sites was further assessed for the metropolitan area of Barcelona. Nutrient recovery from current composting and anaerobic digestion of urban sourced organic matter obtained each year in the area as well as the composting of wastewater sludge, struvite precipitation and ion exchange in wastewater effluent generated yearly in existing WWTPs were assessed. The results show that the requirements for the current and prospective UA in the area can be met 2.7 to 380.2 times for P and 1.7 to 117.5 times for N depending on the recovery strategy. While the present results are promising, current perceptions, legislation and the implementation and production costs compared to existing markets do not facilitate the application of nutrient recovery strategies, although a change is expected in the near future

    Potential Use of Superabsorbent Polymer on Drought-Stressed Processing Tomato (Solanum lycopersicum L.) in a Mediterranean Climate

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    Drought risk is significantly increasing as a consequence of climate change, and the Mediterranean basin will be among the most affected areas by water scarcity in Europe. The development of agronomic strategies enabling the reduction in drought stress in cultivated crops is, therefore, a crucial priority. Superabsorbent polymers (SAPs) are soil amendments capable to retain water and release it when drought occurs. In the present study, the ability of a commercial SAP to improve the drought tolerance of processing tomato (Solanum lycopersicum L.) was assessed on a commercial farm located in northern Italy. A strip plot experimental design was adopted, where three irrigation treatments (IRR100, IRR75, and IRR50, respectively, restituting 100%, 75%, and 50% of crop evapotranspiration) were combined with the application of the SAP (control vs. soil amended with SAP). No significant interaction was observed between irrigation treatments and SAP application in yield and quality traits. SAP application allowed for an average increase in tomato yield (+16.4%) and irrigation water use efficiency (IWUE) (+15.8%), determined by a higher number of marketable fruits. The irrigation strategy IRR75 + SAP maintained the same yield and quality as the full irrigation control (IRR100), increasing the IWUE by about 37%. The experiment demonstrated that, for processing tomatoes grown in the Mediterranean, it is possible to reduce the water supply by 25% when SAP amendment is applied to the soil

    Graphene Oxide-Based Hybrids for Chemiresistive VOCs Sensors

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    INTRODUCTION The sensing of gas molecules is of primary importance for environmental monitoring, control of chemical processes, medical applications, and so on1. In recent years, graphene-based gas sensors have attracted much attention due to enhanced graphene thermo-electric conductivity, surface area and mechanical strength. Thus, different structures have been developed and high sensing performances and room temperature working conditions were achieved1. However, they still suffer from several problems, which could be overcome by covering the graphene surface with metal oxide nanoparticles2. Furthermore, studies regarding the detection of Volatile Organic Compounds (VOCs) are still at the beginning1. Hence, the present work will be aimed at: i) optimizing the synthetic routes of ad hoc composite VOCs sensing materials (based on graphene oxide/SnO2 or ZnO hybrids) and their deep physico-chemical characterizations; ii) engineering the gas sensor device; and iii) evaluating the sensing performances at both high and mild temperatures (also exploiting the UV light) towards gaseous ethanol, acetone and ethylbenzene. EXPERIMENTAL/THEORETICAL STUDY Starting from pure graphite, graphene oxide (GO) powder was synthesized by adopting the Hummer\u2019s modified method2. The synthetic route was deeply investigated by modulating both the starting carbon material (powder or flakes graphite) and the concentration of the H2O2 (i.e. the quenching/oxidizing agent), thus tailoring the final GO surface/structural properties. Once optimized this step, SnO2 or ZnO were grown on its surface by a hydrothermal method, varying the starting salt precursor/GO weight ratio (ZnxGO or SnxGO, x = 4, 8, 16, 32). For comparison, pure SnO2 and ZnO (both commercial and home-made) were also tested. Several physico-chemical techniques have been used to characterize all the as-prepared nanopowders, such as XRPD, BET, Raman, FTIR, XPS, TEM and electrochemical analyses (CV and EIS). Subsequently, a homogeneous layer was deposited by spraying technique onto Pt-Interdigitated Electrodes (IDEs) starting from an ethanol suspension of each sample (2.5 mg mL-1). Then, gaseous ethanol, acetone and ethylbenzene (the more interesting one, being nowadays the less studied VOC) were sensed by using a Linkam Scientific stage, equipped with an electrochemical workstation for the chronoamperometric measurements. RESULTS AND DISCUSSION The effective synthesis of graphene oxide sheets and, subsequently, the growth of metal oxide nanoparticles on its surface were confirmed by exploiting different physico-chemical techniques. As concerns the VOCs sensing analyses, we obtained very promising results (in terms of both response/recovery time and sensibility down to ppb levels) for either pure and hybrid materials at 350\ub0C, and at lower temperatures (150\ub0C to RT, by exploiting UV light) for the graphene-based samples (Figure 1), thanks to the presence of the carbon material.Furthermore, a similar behavior has been noticed towards acetone and ethylbenzene pollutants. CONCLUSION Very promising results have been obtained with graphene oxide-based materials, which reveal to be more performing than the corresponding pure samples. Hence, these powders may represent very potential candidates for the gas sensing of highly toxic VOCs traces, both for environmental and medical diagnosis1 purposes

    Equine cheek tooth extraction: Comparison of outcomes for five extraction methods

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    BACKGROUND: Post-operative complications are reported for all methods of equine cheek tooth extraction but not all methods carry the same risks. An outcome comparison for commonly used methods is needed so that clinicians can make informed treatment decisions. OBJECTIVES: We conducted a side-by-side comparison of five cheek tooth extraction methods, comparing types and incidence of complications among oral extraction, tooth repulsion (three surgical approaches) and lateral buccotomy techniques. STUDY DESIGN: Retrospective clinical study using hospital medical records. METHODS: Medical records of all horses undergoing cheek tooth extraction between 1997 and 2013 were reviewed. Logistic regression was used to determine the likelihood of various post-operative complications, comparing oral extraction, tooth repulsion by maxillary and mandibular trephination or maxillary sinus bone flap, and lateral buccotomy. RESULTS: The study included 137 horses and 162 cheek teeth extractions. Oral extraction was successful in 71% of patients in which it was attempted. Oral extraction (n = 55) had the lowest incidence of complications (20%) and repulsion by sinus bone flap (n = 20) the highest (80%). Complication rates for repulsion by maxillary (n = 19) and mandibular trephination (n = 28), and extraction by lateral buccotomy (n = 15) were 42, 54 and 53%, respectively. Cheek tooth repulsion by sinus bone flap significantly increased the odds of damage to adjacent teeth, post-operative sinusitis, damage to alveolar bone, delayed alveolar granulation and orosinus fistulation. Repulsion by maxillary trephination significantly increased the odds of superficial incisional surgical site infection; and extraction by lateral buccotomy significantly increased the odds of facial nerve neuropraxia. Post-operative pyrexia was more common in all repulsion methods. MAIN LIMITATIONS: Some clinically relevant differences may have been missed due to small group numbers in several categories. CONCLUSIONS: Oral extraction was associated with fewer post-operative complications than any other methods. Standing oral extraction remains the preferred choice, and recent surgical advances promise to further improve its success rate

    Correlative Microscopy Of Bone In Implant Osteointegration Studies.

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    Routine morphological analyses usually include investigations by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Each of these techniques provides specific information on tissue morphology and all the obtained results are then combined to give an in-depth morphological overview of the examined sample. The limitations of this traditional comparative microscopy lie in the fact that each technique requires a different experimental sample, so that many specimens are necessary and the combined results come from different samples. The present study describes a technical procedure of correlative microscopy, which allows us to examine the same bone section first by LM and then, after appropriate processing, by SEM or TEM. Thanks to the possibility of analyzing the same undecalcified bone sections both by LM and SEM, the approach described in the present study allows us to make very accurate evaluations of old/new bone morphology at the bone-implant interface

    Detection of VOCs Traces by Graphene Oxide-Metal Oxide Gas Sensors

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    The sensing of gas molecules is of fundamental importance for environmental monitoring, control of chemical processes, medical applications, and so on [1-3]. In recent years, graphene-based gas sensors have attracted much attention due to enhanced graphene thermo-electric conductivity, surface area and mechanical strength. Thus, different structures have been developed and high sensing performances and room temperature working conditions were achieved [2,4]. However, they still suffer from several problems, which could be overcome by covering the graphene surface with metal oxide nanoparticles [2]. Furthermore, studies regarding the detection of Volatile Organic Compounds (VOCs) are still at the beginning [3]. Hence, the present work will be aimed at: i) optimizing the synthetic routes of ad hoc composite VOCs sensing materials (based on graphene oxide/SnO2 or ZnO hybrids) and their deep physico-chemical characterizations; ii) engineering the gas sensor device; and iii) evaluating the sensing performances at both high and mild temperatures (also exploiting the UV light) towards gaseous ethanol, acetone and ethylbenzene. Starting from pure graphite, graphene oxide (GO) powder was synthesized by adopting the Hummer\u2019s modified method [5]. The synthetic route was deeply investigated by modulating both the starting carbon material (powder or flakes graphite) and the concentration of the H2O2 (i.e. the quenching/oxidizing agent), thus tailoring the final GO surface/structural properties (TEM images in Fig. 1a and 1b). Once optimized this step, SnO2 or ZnO were grown on its surface by a hydrothermal method, varying the starting salt precursor/GO weight ratio between 4 and 32 (Fig. 1c and 1d). For comparison, pure SnO2 and ZnO (both commercial and home-made) were also tested. Several physico-chemical techniques have been used to characterize all the as-prepared nanopowders, such as XRPD, Raman, FTIR, XPS and TEM analyses. Subsequently, a homogeneous layer was deposited by spraying technique onto Pt-Interdigitated Electrodes (IDEs) starting from an ethanol suspension of each sample (2.0\u20132.5 mg mL-1). Then, gaseous ethanol, acetone and the less studied ethylbenzene were sensed, obtaining very promising results (in terms of both response/recovery time and sensibility down to ppb levels) for either pure and hybrid materials at 350\ub0C, and at lower temperatures (150\ub0C to 30\ub0C) for the graphene-based samples. Hence, these powders may represent very potential candidates for the gas sensing of highly toxic VOCs traces, both for environmental [1] and medical [3] diagnosis purposes
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