Multi-wavelength observations of planet forming disks: Constraints on planet formation processes

Our understanding of protoplanetary disks has greatly improved over the last decade due to a wealth of data from new facilities. Unbiased dust surveys with Spitzer leave us with good constraints on the dust dispersal timescale of small grains in the terrestrial planet forming region. In the ALMA era, this can be confronted for the first time also with evolutionary timescales of mm grains in the outer disk. Gas surveys in the context of the existing multi-wavelength dust surveys will be a key in large statistical studies of disk gas evolution. Unbiased gas surveys are limited to ALMA CO submm surveys, where the quantitative interpretation is still debated. Herschel gas surveys have been largely biased, but [OI] 63 mic surveys and also accretion tracers agree qualitatively with the evolutionary timescale of small grains in the inner disk. Recent advances achieved by means of consistent multi-wavelength studies of gas AND dust in planet forming disks reveal the subtleties of the quantitative interpretation of gas surveys. Observational methods to determine disk masses e.g. from CO submm lines require the knowledge of the dust properties in the disk. Understanding not only the gas evolution, but also its chemical composition will provide crucial input for planet formation models. Kinetic chemical results give profoundly different answers than thermodynamic equilibrium in terms of the C/O ratios as well as the water ice/rock ratios. Again, dust has a key impact on the chemical evolution and composition of the gas. Grain growth for example affects freeze-out processes and strongly increases the cosmic ray induced UV field.Comment: appears in the proceedings of the conference "The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life", October 17-20, 2017, Tokyo, Japa

Permeability evolution during progressive development of deformation bands in porous sandstones

[1] Triaxial deformation experiments were carried out on large (0.1 m) diameter cores of a porous sandstone in order to investigate the evolution of bulk sample permeability as a function of axial strain and effective confining pressure. The log permeability of each sample evolved via three stages: (1) a linear decrease prior to sample failure associated with poroelastic compaction, (2) a transient increase associated with dynamic stress drop, and (3) a systematic quasi-static decrease associated with progressive formation of new deformation bands with increasing inelastic axial strain. A quantitative model for permeability evolution with increasing inelastic axial strain is used to analyze the permeability data in the postfailure stage. The model explicitly accounts for the observed fault zone geometry, allowing the permeability of individual deformation bands to be estimated from measured bulk parameters. In a test of the model for Clashach sandstone, the parameters vary systematically with confining pressure and define a simple constitutive rule for bulk permeability of the sample as a function of inelastic axial strain and effective confining pressure. The parameters may thus be useful in predicting fault permeability and sealing potential as a function of burial depth and faul

Mid-IR spectra of pre-main sequence Herbig stars : an explanation for the non-detections of water lines

The research leading to these results has received funding from the European Union Seventh Framework Programme FP7-2011 under grant agreement No. 284405.Context. The mid-IR detection rate of water lines in disks around Herbig stars disks is about 5%, while it is around 50% for disks around T Tauri stars. The reason for this is still unclear. Aims. In this study, we want to find an explanation for the different detection rates between low mass and high mass pre-main-sequence stars in the mid-IR regime. Methods. We ran disk models with stellar parameters adjusted to spectral types B9 through M2, using the radiation thermo-chemical disk modelling code ProDiMo. We explored also a small parameter space around a standard disk model, considering dust-to-gas mass ratio, disk gas mass, mixing coefficient for dust settling, flaring index, dust maximum size, and size power law distribution index. We produced convolved spectra at the resolution of Spitzer, IRS, JWST MIRI, and VLT VISIR spectrographs. We applied random noise derived from typical Spitzer spectra for a direct comparison with observations. Results. The strength of the mid-IR water lines correlates directly with the luminosity of the central star. The models show that it is possible to suppress the water emission; however, current observations are not sensitive enough to detect mid-IR lines in disks for most of the explored parameters. The presence of noise in the spectra, combined with the high continuum flux (noise level is proportional to the continuum flux), is the most likely explanation for the non-detections towards Herbig stars. Conclusions. Mid-IR spectra with resolution higher than 20 000 are needed to investigate water in protoplanetary disks. Intrinsic differences in disk structure, such as inner gaps, gas-to-dust ratio, dust size and distribution, and inner disk scale height, between Herbig and T Tauri star disks are able to explain a lower water detection rate in disks around Herbig stars.Publisher PDFPeer reviewe

Development of an integrated work-flow for biochemical underground hydrogen storage modelling

LAUREA MAGISTRALECon la transizione energetica in atto nei prossimi anni, al sistema energetico nazionale si aggiungerà una quantità significativa di produzione variabile di energia rinnovabile da impianti eolici e solari. Questa condizione farà sorgere la necessità di impianti di stoccaggio di grandi dimensioni e di lunga durata, in grado di gestire la stagionalità della produzione di energia elettrica rinnovabile. La trasformazione di tale energia elettrica in energia chimica legata all'idrogeno mediante elettrolizzatori sta ricevendo sempre più riconoscimento in ambito scientifico. Una volta prodotte, le molecole di H2 devono essere immagazzinate per lunghi periodi di tempo; poiché i serbatoi in superficie non sembrano essere in grado di svolgere completamente questo compito, molti studi si stanno concentrando sullo stoccaggio sotterraneo dell'idrogeno come alternativa. Questo tipo di stoccaggio può essere effettuato in quattro diverse formazioni sotterranee: caverne di roccia rivestite artificialmente, caverne saline, falde acquifere profonde e giacimenti di petrolio e gas esauriti. Molti aspetti di questo tipo di stoccaggio richiedono progetti dedicati per essere completamente compresi; questa tesi si concentra principalmente su due diversi aspetti che sono rilevanti quando si studia un caso realistico di un campo a gas esaurito: 1. La più rilevante attività biochimica che ha luogo nelle formazioni sotterranee, ossia la proliferazione di agenti metanogeni, viene studiata, modellata e simulata. Il suo impatto, che dipende dalle condizioni del giacimento e dalle scelte operative, è stato valutato attraverso un approccio di analisi di sensitività su diversi parametri. 2. Le principali variabili di operatività dell'impianto vengono modificate al fine di sviluppare una procedura universale per comprendere: la capacità di stoccaggio reale, le strategie decisionali riguardo il cushion gas. Inoltre, viene aggiunta un'analisi finale sulla flessibilità della portata programmata, per comprendere meglio il reale potenziale della tecnologia di stoccaggio nelle proiezioni future di un sistema energetico nazionale completamente decarbonizzato. Per realizzare il primo task è stata eseguita una procedura di messa a punto per modellare il tasso di proliferazione degli agenti metanogeni in base alla concentrazione acquosa di H2 e CO2 nel campo. Insieme ad essa, è stata effettuata la stima della costante di equilibrio liquido-vapore alle condizioni del giacimento per ciascun componente della miscela fluida. Una volta affrontate completamente le questioni tecniche, sono state effettuate analisi di sensitività che hanno mostrato che una grande quantità di CO2 nel serbatoio è effettivamente un problema, ma se questo parametro viene tenuto sotto controllo la perdita massima di H2 dovuta ai metanogeni rimane inferiore al 3% rispetto allo stesso caso senza microrganismi. Per quanto riguarda il secondo task, sono state simulate molte configurazioni per valutare l'effettivo potenziale del campo Nissa senza includere le perdite di microrganismi che avrebbero avuto un impatto marginale in uno scenario di lungo periodo. Da questo punto di partenza è stato possibile valutare l'impatto della molecola e della quantità di cushion gas, il numero di pozzi da realizzare, l'importanza della spinta dell'acquifero e i benefici correlati a una programmazione flessibile delle portate da iniettare e produrre. I risultati finali mostrano che: • La molecola H2 come cushion gas è preferibile da un punto di vista tecnico anche se l'opzione CH4 potrebbe essere più economica, • Aspetti critici come la possibilità di inserire un periodo di inattività tra l'iniezione del cushion gas e la prima iniezione di esercizio potrebbero aumentare la capacità stimata dell'impianto specifico • Il passaggio rapido tra un periodo di iniezione e uno di produzione può portare forti benefici alla gestione dell'acquifero e alla purezza del gas prodotto.With energy transition happening in the next future years, a significant amount of variable renewable energy production from wind and solar power plants will be added to the national energy system. This condition will arise the need in large amount and long period storage facilities that can handle the seasonality of renewable electricity generation. The transformation of such electricity into chemical energy related to hydrogen using electrolysers is getting more and more attention. Once the H2 molecules are produced they have to be stored for long periods of time, since up-surface tanks doesn’t seem to be able to fulfil the task completely much research is focusing on Underground Hydrogen Storage (UHS) as an alternative. This type of storage can be done in four different sub-surface formations: lined rock caverns, salt caverns, deep aquifers, and depleted oil and gas fields. Many aspects of UHS require dedicated projects to be completely understood, this thesis focuses mainly on two different aspects that are relevant when a realistic depleted gas field facility is under investigation: 1. The main bio-chemical activity that takes place in underground formations i.e. Methanogenic Archaea proliferation is studied, modelled and simulated. Its impact depending on reservoir conditions and operational choices is evaluated through a sensitivity analysis approach on different parameters 2. The main plant operability parameters are varied in order to develop an extendable procedure to understand: realistic storage capacity, cushion gas decision marks. Plus a final sensitivity analysis on scheduled flowrate flexibility is added to better understand the real potential of this technology in future projections of a national energy system completely decarbonized To realize the first task a tuning procedure to model the proliferation rate of Methanogenic Archaea based on H2 and CO2 aqueous concentration in the sub-surface field was done. Together with it, the estimation of Vapour-Liquid equilibrium constant at reservoir conditions for each component in the fluid mixture was done. Once the technical issues were completely addressed the sensitivity analysis were made and showed that a large amount of CO2 in reservoir is actually an issue, but if this parameter is kept under control the maximum H2 loss due to methanogens remains below 3% with respect to the same case without microorganism. Regarding the second task many configurations have been simulated to evaluate the actual potential of the Nissa field without including the microorganism losses that would have had a marginal impact over a long period of operation. From that starting point the impact of the cushion gas molecule and amount, the number of wells to put in place, the aquifer push importance and benefits correlated to a flexible schedule were understood. Final results show that: • H2 molecule as a cushion gas is from a technical point of view preferable even if CH4 option might be cheaper, • Critical aspects like the possibility to insert an idle period between the cushion gas injection and the 1st injection of operation might increase the estimated capacity of the specific facility • Flexible switching between injection and production operation on daily basis brings strong benefits on water management and gas production stream purit

Phase I and pharmacokinetic study of brostallicin (PNU-166196), a new DNA minor-groove binder, administered intravenously every 3 weeks to adult patients with metastatic cancer

PURPOSE: Brostallicin (PNU-166196) is a cytotoxic agent that binds to the minor groove of DNA with significant antitumor activity in preclinical studies. This trial was designed to determine the maximum tolerated dose, the toxicity profile, and the pharmacokinetics of Brostallicin in cancer patients. Experimental Design: Patients were treated with escalating doses of Brostallicin ranging from 0.85 to 15 mg/m(2) administered as a 10-min i.v. infusion every 3 weeks. Blood samples for pharmacokinetic analysis were collected during the first and second course, and analyzed by liquid-chromatography with tandem-mass spectrometric detection. RESULTS: Twenty-seven evaluable patients received a total of 73 courses. Grade 4 neutropenia was the only dose-limiting toxicity at 12.5 mg/m(2), whereas grade 4 thrombocytopenia (1 patient) and grade 4 neutropenia (2 patients) were the dose-limiting toxicities at 15 mg/m(2). Other side effects, including thrombocytopenia and nausea, were generally mild. The maximum tolerated dose was defined at 10 mg/m(2). The clearance and terminal half-life of Brostallicin were dose-independent, with mean (+/-SD) values of 9.33 +/- 2.38 liters/h/m(2) and 4.69 +/- 1.88 h, respectively. There was no significant accumulation of Brostallicin with repeated administration. Significant relationships were observed between systemic exposure to Brostallicin and neutrophil counts at nadir. One partial response was observed in a patient with a gastrointestinal stromal tumor. CONCLUSION: Brostallicin was found to be well tolerated, with neutropenia being the principal toxicity. The recommended dose for additional evaluation in this schedule is 10 mg/m(2)

Water in protoplanetary disks:Line flux modeling and disk structure

Protoplanetary disks are the places in which planets form around young stars. These environments consist of dust and gas mainly in forms of molecules. Simple and abundant molecules such as water, carbon monoxide, ammonia, play an important role in the disk thermal balance, and allow also observers to study these objects. Water is an abundant molecule with a rich spectroscopy in the entire IR spectral regime. It can be used to probe local gas physical conditions from the inner through the outer disk. Observations of water show often non-detections for still unclear reasons. With this thesis we suggest an explanation based on the physical properties of individual protoplanetary disks, their central star and mid-IR dust spectral features. Finally we investigate the hidden reservoirs of water and other volatile species frozen in the coldest regions of the disk. We conclude that opacity due to the dust is one of the main causes for the suppression of both mid-IR and far-IR water lines in disks. Disks around more luminous central stars from modeling, should have stronger mid-IR water lines, but the stronger continuum produced by the warmer dust buries the lines. We also found that the presence of stronger mid-IR water line fluxes can be consistent with disks depleted in dust or enhanced in gas abundance in the innermost regions. Finally, time-dependent chemistry is not important in the evolution for the two-dimensional distribution of water and other ices in disks after 100.000 yrs

Analisi dati di un prototipo di camera a deriva per l'esperimento DUNE

Le camere a deriva sono rivelatori utilizzati per tracciare il passaggio di particelle cariche che basano il loro funzionamento sulla ionizzazione del gas contenuto al loro interno e sul moto di deriva delle cariche soggette a un campo elettrico. Il Deep Underground Neutrino Experiment (DUNE), attualmente in fase di costruzione negli Stati Uniti, sta investigando la possibilità di utilizzare nel sito del Near Detector, all'interno del rivelatore SAND, una camera a deriva come tracciatore per particelle prodotte nelle interazioni di neutrini. In questo lavoro di tesi è stata realizzata la prima analisi dati di un prototipo di camera a deriva costruito all'INFN di Bologna per DUNE

Irrigation Management in Coastal Zones to Prevent Soil and Groundwater Salinization

Soil salinization is one of the most widespread soil degradation processes on earth and, worldwide, one billion hectares are affected, mainly in the arid–semiarid regions of Asia, Australia and South America [1]. In Europe, soil salinity has effects on one million hectares mainly in the Mediterranean countries [1]. There are two types of salinization: primary salinization caused by natural events such as sea spray or rock weathering or seepage [2] and secondary salinization that is caused by human activities such as irrigation with salty water, groundwater overexploitation and excessive drainage [1]. Along the Adriatic coast of the Po Plain, freshwater resources are becoming increasingly scarce, because of irrigation and other intense water use, salinization and long periods of drought [3]. Custodio [4] underlines that, especially in southern Europe, the irrigation practices and the water requirements to sustain the coastal tourism industry exhort a strong pressure on water resources. The impact of groundwater salinization in coastal areas affects both natural vegetation biodiversity and agricultural production, through soil salinization and reduction of freshwater availability for irrigation. Salinization is closely associated with the process of desertification, because salinity may have direct negative effects on crop yields by reducing the ability of plant roots to take up water [5]. The most common salinity effect is a general stunting of plant growth, but not all plants respond in the same way. Grain and corn may reduce their seed production without appreciably plant dimensions reduction