1,720,977 research outputs found
Indagini idrogeochimiche per la caratterizzazione degli acquiferi e proposta di un nuovo protocollo di trasmissione per il monitoraggio chimico fisico.
No full textQuesta tesi presenta i risultati di uno studio idrogeochimico sulla falda acquifera della pianura alluvionale nella provincia di Ferrara, come strumento per una migliore conoscenza del territorio. Le caratteristiche chimiche delle falde acquifere sono state indagare attraverso 343 analisi chimiche dei campioni di acqua (253 dal campionamento delle acque freatiche e 90 dal database regionale raccolti negli anni 2003-2015). La maggior parte delle acque hanno facies Ca-HCO3; pochi sono di tipi di NaCl, CaCl e NaHCO3. L'applicazione di analisi fattoriale alle analisi chimica ha permesso di identificare tre diversi gruppi di fattori che riducono il numero di attributi utili alla definizione dei raggruppamenti. Gruppo 1: comprendono campioni affetti da processi di scambio ionico; Gruppo 2: acque con pH basso e arricchite in metalli pesanti. Gruppo 3: campioni con alta concentrazione di HCO3. I cambiamenti climatici come l'aumento delle temperature e la diminuzione delle precipitazioni sono causate da anomalie climatiche che si riflettono in composizione isotopica di acque sotterranee. Questi cambiamenti climatici possono essere convalidate mediante la presenza di isotopi pesanti nelle acque sotterranee (2H e 18O). L’ interpretazione dei parametri climatici e un approccio statistico-idrogeochimico per lo studio dei dati su acque sotterranee sono i metodi adottati in questa ricerca. Un approccio multidisciplinare è necessario per comprendere le alterazioni alle quali le acque sono sottoposte. La composizione isotopica delle acque è nel range -10,75; -6,03 per Delta-O-18 e, -71 3 - 43, 71 per δ2H. Ciò suggerisce un origine meteorica per l'acqua ricarica. Gli approcci combinati di idrogeochimica e climatologia ci hanno permesso di rilevare i processi climatici che influenzano le risorse idriche del terreno in modo più preciso, e questi approcci rappresenteranno eccellenti strumenti di valutazione necessari per il comando bilancio idrico nella ricerca futura. I modelli geochimici sono stati usati per comprendere meglio le reazioni geochimiche che avvengono e spiegare la composizione delle acque. I maggiori cambiamenti nella composizione geochimica possono essere attribuiti a cambiamenti nella mineralogia e petrografia dei sedimenti: le acque profonde sono caratterizzate da una marcata presenza di HCO3 e basso Mg, l'acqua di superficie da un marcatore di Mg. Le acque freatiche a contatto con minerali argillosi ricevono il magnesio attraverso la lisciviazione di smectite / clorite dei sedimenti i quali hanno una capacità di scambio cationico in rapporto alla loro struttura cristallina (Ca, Na e Mg). Nelle reazioni osservate svolge un ruolo determinante scambio ionico tra Ca e Na e la risalita di acque provenienti da settori profondi le quali risalgono lungo faglie e fratture grazie alla diminuzione di densità dovuta a CH4 in soluzione. Il metano può derivare da fonti profonde e localmente dalla presenza di materiale organico che svolge un ruolo importante nello scambio di cationi da acqua / suolo il quale è stato osservato in un aumento della (capacità di scambio cationico) CEC.
Per facilitare le pratiche di acquisizione dei dati di monitoraggio nell’ambito di questo lavoro è stato messo a punto un nuovo sistema di trasmissione basato su ARDUINO. Questa scheda è stata connessa ad un antenna GSM che invia i dati direttamente a un database nel cloud in cui è possibile leggere i dati in tempo reale. Il lavoro geochimici ha rappresentato uno strumento utile alla identificazione dei siti in cui sarà interessante posizionare il sistema di monitoraggio in continuo per espandere quello esistente con l'introduzione di nuove tecnologie. L'uso di questo strumento di gestione a basso costo e di facile utilizzo permetterà di migliorare la gestione delle risorse idriche.This thesis presents the results of a hydrogeochemical study on the aquifer Po floodplain, as a tool for the knowledge and definition of the best location of the new continuous monitoring system. The chemical characteristics of the aquifers have been investigate through 343 chemical analysis of water samples (253 from phreatic water sampling and 90 from the regional database collected in the years from 2003 to 2015). Most of the waters have Ca-HCO3 facies; few are of NaCl, CaCl and NaHCO3 types. The application of Factorial Analysis to the chemical analysis allowed identifying three different groups of water. Group 1: comprise samples affected by ion exchange processes; Group 2: waters with low pH and enriched in heavy metals. Group 3: samples with high concentration in HCO3. Climate changes such as increasing temperatures and decreasing precipitations are caused by climatic anomalies which are mirrored in groundwater’s isotopic composition. These climatic changes can be validated by means of the presence of heavy isotopes in ground water (2H and 18O) . The heavy isotopes can bring to the enrichment or the impoverishment of waters.
A multidisciplinary approach is required to understand the alterations the waters are undergoing. The main effects of the climatic anomalies, which are reflected on ground water resources, are isotopic ratio depletion and increasing evaporation . They can be spotted in the isotopic ratio change and in the grade line comparing it to the North Meteoric Water Line (NMWL).
The isotope composition of the waters is in the range -10.75; -6.03 for δ18O and, -71, 3 - 43, 71 for δ2H. This suggest a meteoric origin for the recharging water. The combined approaches of hydrogeochemistry and climatology have enabled us to detect those climatic processes affecting ground water resources in a more accurate way, and these approaches will represent excellent assessment tools required for controlling water balance in future research.
Modelling has been use to better understand the geochemical reactions that take place and explain the groundwaters composition. The biggest changes in the geochemical composition can be attributed to changes in mineralogy and petrography of the sediment: deep waters are characterized by a marked presence of HCO3 and low Mg, the phreaticwater from an Mg marker. The phreaticwater being in contact with clays minerals and receive the magnesium through the leaching of smectite/chlorite of the sediments and then characterized in reason of their crystalline structure have a high cation exchange capacity (for Ca, Na and Mg).
In the observed reactions play a determinant role ion exchange between Ca and Na and the rise of deep water rich in salt along faults and fractures thanks the decrease of density due to CH4 in solution. The methane may arise from deep sources and by locally presence of organic matter which play an important role in exchange of cations from water/soil as has been observe in an increase of the CEC (cation exchange capacity)
A new monitoring transmission protocol have been create using the microcontroller ARDUINO to facilities the monitoring groundwaters practices. This card has been connect to a GSM antenna which sends data directly to a database in the cloud where is possible to read real-time data recorded. The geochemical work have represent a tool to identify sites where will be interesting to place the continuously monitoring system to expand the existing one with the introduction of new technologies. The use of this low cost and easy management tool will allow an improvement in the water resource management
Amino-sugar modular ligands-useful cores for the formation of asymmetric copper 1,4-addition catalysts
No full textModular phosphine ligands, synthesized rapidly from com. N-acetylglucosamine, are very effective in copper(I)-catalyzed 1,4-addns. of ZnR2 to linear aliph. enones (87-95% ee)
Carbohydrates as building blocks of privileged ligands for multiphasic asymmetric catalysis
No full textCarbohydrates as building blocks of privileged ligands
No full text“Privileged ligands” are chiral auxiliaries of wide applicability in asymmetric catalysis. In the previous decades, their effective three-dimensional structures have often been reproduced by using building blocks from a “chiral pool”, such as the carbohydrates. This strategy has provided unique ligand moieties which combine the performance of “privileged ligands” with increased flexibility and accessibility. This review gives an overviewof the research within this field, giving emphasis to the best results obtained with each ligand type
Carbohydrates as building blocks of "privileged" ligands for multiphasic asymmetric catalysis
No full textAn Evaluation Method of the Building Decarbonization Process at the International Level
No full textThe anthropogenic greenhouse effect results from human activity that causes greenhouse gas (GHG) emissions, the effects of which are now directly observable in terms of pollution and global warming. Among the negative consequences of rising global temperatures are the advancing processes of desertification, rising water levels, and biodiversity loss. The seriousness of the problem is underlined by the many plans and policies being implemented by governments internationally. The paper analyses the real estate sector’s responsibility for GHG emissions. The existing building stock, built before introducing energy efficiency measures, needs to be energetically renovated to meet the current requirements and performance standards that governments now demand. The paper presents an analysis of forecast data from the Carbon Risk Real Estate Monitor (CRREM) project, an EU-funded initiative to provide information on the decarbonization path to be followed by the existing building stock in 30 European countries. The study’s contribution is the construction of a Building Decarbonisation Performance Index (IBDP). The index was constructed using forecast data provided by the CRREM project, which were processed by implementing the operational logic of multi-criteria techniques. IBDP was designed with the objective of monitoring and assessing the degree of alignment between European countries and the decarbonization paths set by EU policies
A convenient route from simple sugars to new chiral bis(phosphinoesters) for asymmetric catalysis
No full textReadily available chiral bis(phosphinoesters) based on d-glucose, d-mannose and d-galactose have been prepared in only two steps and in large scale starting from inexpensive commercial precursors. Their Pd complexes catalyze the asymmetric desymmetrization of meso-cyclopent-4-ene-1,3-diol biscarbamate in ee’s up to 82%
Carbohydrates as building blocks of privileged ligands for multiphasic asymmetric catalysis
No full textTo combine the high chem. performance of asym. catalysis with the increasing need fo sustainability, a strategy is presented that involves the straightforward prepn. of "Trost"-like ligands suitable for application in multiphasic homogeneous catalysis. Ligands with coordinating functions (phosphinoamide-phosphinoester groups) as well as phase tags introduced on a D-glucose scaffold were prepd. and then examd. in the Pd-catalyzed asym. desymmetrization of meso-2-cyclopenten-1,4-diol biscarbamate. In line with our assumption, the performance of the catlyst system under traditional conditions is as high as that of the original Trost ligand, derived from trans-cyclohexanediamine, giving enantioselectivities of 98 % ee. Moreover, promising results were obsd. under multiphasic homogeneous conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
