1,125 research outputs found
What are the factors driving the adoption and intensity of sustainable irrigation technologies in Italy?
This paper aims to analyse the determinants of Italian farmers’ adoption of sustainable irrigation technologies such as micro-irrigation (drip and sprinklers) and sub-irrigation technologies. To improve farmers’ water management, climate variability adaptive behaviour should be incentivized. Italy, like other Mediterranean countries, has suffered the most for an increase in frequency and intensity of droughts, higher temperatures and fewer precipitations. Applying innovative irrigation systems, water scarcity and water stress may be overcome. Water conservation and saving technologies may help in supporting water-saving behaviour, increasing water conservation in the natural environment and reducing water stress to cultivations. However, accurate analyses of the determinants of adoption and intensity of these techniques are still scarce. This study fills this gap by using a micro-level approach which combines yearly Agricultural Accounting Information Network (RICA) datasets with climatic variables from the ERA-Interim dataset. Based on an unbalanced panel dataset for the period 2012-2016, the decision of a farmer whether to adopt an irrigation saving technology or not is estimated applying a logit and a probit model, while the intensity of adoption is estimated through a Tobit model. Our main findings confirm that crop typology, education, geography and climate are all relevant factors influencing the sustainable irrigation technology adoption choice as well as the adoption intensity given that most farmers adopt water-saving technologies only partially
Risk Attitudes to Catastrophic Events: VSL and WTP for Insurance Against Earthquakes
The purpose of the paper is to investigate the attitude to risk related to low-probability, high-impact events. To do this, we compare the willingness to pay (WTP) to reduce mortality risks and the WTP for life insurance against earthquakes. We explore whether risk perception affects these measures, and exploit WTP to reduce risk of fatality to calculate the Value of a Statistical Life (VSL) related to seismic events. We rely on data from a survey administered to a representative sample of the Italian population. Our results highlight that the WTP to reduce mortality risk is lower than the WTP for life insurance, and that the correlations between risk perception and these two measures differ. The findings suggest that individuals’ preferences are directed toward risk management strategies in which the mortality risk is transferred to the capital market, rather than risk mitigation strategies involving the individual in sharing the costs and benefits with all of society
Conformational Studies by Dynamic NMR. 97.Structure, Conformation, Stereodynamics and Enantioseparation of Aryl Substituted Norbornanes.
CAN 140:163414 AN 2003:996217 CAPLUS (COPYRIGHT (C) 2008 ACS ON SCIFINDER (R))
ABSTRACT
THE STRUCTURE OF A 1,7,7-TRIARYLNORBORNANE (I) HAS BEEN DETD. BY X-RAY DIFFRACTION AND WAS FOUND ESSENTIALLY EQUAL TO THAT PREDICTED BY MOL. MECHANICS CALCNS. RESTRICTED ROTATION OF THE ARYL GROUPS ALSO HAS BEEN OBSD. BY DYNAMIC NMR SPECTROSCOPY IN THIS COMPD. AND IN A NO. OF ANALOGOUSLY SUBSTITUTED NORBORNANES. THE ARYL-NORBORNANE BOND ROTATION BARRIERS WERE MEASURED BY LINE SHAPE ANAL. OF THE 13C NMR SPECTRA OBTAINED AT TEMPS. LOWER THAN -100 °C AND WERE FOUND TO COVER THE RANGE 6.0 TO 7.9 KCAL MOL-1. AN EXCEPTION WAS THE ROTATION INVOLVING THE O-ANISYL GROUP IN II, WHICH OCCURS NEAR AMBIENT TEMP. SINCE THE CORRESPONDING BARRIER IS MUCH HIGHER (14.4 KCAL MOL-1). IN ONE CASE (III) CONFIGURATIONAL ENANTIOMERS COULD BE SEPD. BY CHIRAL HPLC AND THE CORRESPONDING CD SPECTRA RECORDED
Synergistic catalysis: cis-cyclopropanation of benzoxazoles
In the present paper we report our latest efforts in pushing the boundaries of Synergistic Catalysis. We propose the use of 3 different catalytic cycles working in concert for the formation of cis cyclopropane derivatives of benzoxazoles with excellent stereoselectivities. This is the proof of concept that synergistic catalysis could be successfully used in cascade reaction
Conformational Studies by Dynamic NMR. 100. Enantiomerization Process of Stereolabile Atropisomers in Pyridine-Substituted Adamantane Derivatives.
CAN 141:224907 AN 2004:566825 CAPLUS (COPYRIGHT (C) 2008 ACS ON SCIFINDER (R))
ABSTRACT
THE BARRIERS FOR INTERCONVERTING THE CONFORMATIONAL ENANTIOMERS (STEREOLABILE ATROPISOMERS) OF PYRIDINE-SUBSTITUTED ADAMANTANE DERIVS. HAVE BEEN DETD. BY DYNAMIC 13C NMR SPECTROSCOPY. THE TREND OF THESE VALUES PARALLELS THAT ANTICIPATED BY MM CALCNS. IN AT LEAST ONE CASE, THE COMPUTED STRUCTURE WAS FOUND TO AGREE WITH THAT OBTAINED BY SINGLE-CRYSTAL X-RAY DIFFRACTION. IN ADDN., IT HAS BEEN POSSIBLE TO ACHIEVE A PHYS. SEPN. OF A PAIR OF THESE STEREOLABILE ATROPISOMERS AT -60 °C BY MEANS OF THE ENANTIOSELECTIVE CRYOGENIC HPLC TECHNIQUE
Sudden death in lambda light chain AL cardiac amyloidosis: a review of literature and update for clinicians and pathologists
Light chain (AL) amyloidosis is the most common type of systemic amyloidosis, affecting around 10 people per million per year. In Europe, approximately 5000 new diagnosis per year are reported. Deposition of amyloid fibrils derived from antibody light chains are key pathogenic agents in AL amyloidosis. They can be deposited in multiple organs but cardiac involvement carries a major risk of mortality. The prognosis is poor in cases associated with multiple myeloma. The average survival is around 1 year. Up to half of all patients with cardiac amyloidosis die suddenly; 75% ofthose deaths are due to heart failure. Ventricular arrhythmia is also associated with cardiac amyloidosis and unexpected death. It is crucial to make a diagnosis and start treatment at an early stage. Recent data suggest that cardiac amyloidosis has become a treatable and curable condition with a combination of agents targeting multiple steps of the amyloid cascade. ICD implantation may not be as effective for the therapy of light chain (AL) cardiac amyloidosis as supposed earlier. In cases of unexpected and sudden death, autopsy may show unknown conditions and is valuable to assess existing risks for family members. Even after careful autopsy, a proportion of sudden deaths, ranging from 2 to 54%, remain unexplained and this broad range of values is likely due to the heterogeneity of autopsy protocols. Post mortem diagnosis of cardiac amyloidosis still represents a challenge for forensic pathologists. Detailed morphologic study of the heart and a complete histopathologic study are mandatory. Immunohistochemistry is essential for amyloid subclassification. A review of existing literature is performed by the authors and a methodological approach in post mortem diagnosis of light chain AL cardiac amyloidosis is proposed. Both macroscopic and microscopic findings are discussed
Chiral nanostructuring of multivalent macrocycles in solution and on surfaces
We describe the design and synthesis of a novel functionality-rich, homochiral macrocycle, possessing the overall molecular D-2 symmetry, in which multivalency is introduced into the covalent framework by means of four suitably positioned pyridine moieties. The macrocycle synthesis is carried out with functionalized, enantiopure 1,1'-binaphthyl synthons as the source of chirality by means of a room temperature esterification reaction as the cyclization procedure. Upon addition of Pd2+, coordination of the pyridine moieties occurs both intra and intermolecularly, to afford chiral ordered mono and dimeric macrocycles or multimeric aggregates depending on the solvents and conditions used. The metal binding event takes place in combination with a significant macrocyclic conformational rearrangement detected by circular dichroism spectroscopy. When in combination with a third component (C-60), the macrocycle-Pd2+ hybrid undergoes surface-confined nanostructuring into chiral nanofibres
Molecular recognition of the HPLC Whelk-O1 selector towards the conformational enantiomers of nevirapine and oxcarbazepine
The presence of stereogenic elements is a common feature in pharmaceutical compounds, and affording optically pure stereoisomers is a frequent issue in drug design. In this context, the study of the chiral molecular recognition mechanism fundamentally supports the understanding and optimization of chromatographic separations with chiral stationary phases. We investigated, with molecular docking, the interactions between the chiral HPLC selector Whelk-O1 and the stereoisomers of two bioactive compounds, the antiviral Nevirapine and the anticonvulsant Oxcarbazepine, both characterized by two stereolabile conformational enantiomers. The presence of fast-exchange enantiomers and the rate of the interconversion process were studied using low temperature enantioselective HPLC and VT-NMR with Whelk-O1 applied as chiral solvating agent. The values of the energetic barriers of interconversion indicate, for the single enantiomers of both compounds, half-lives sufficiently long enough to allow their separation only at critically sub-ambient temperatures. The chiral selector Whelk-O1 performed as a strongly selective discriminating agent both when applied as a chiral stationary phase (CSP) in HPLC and as CSA in NMR spectroscopy
Quantification of the Lewis Basicities and Nucleophilicities of 1,3,5-Tris(dialkylamino)benzenes
AbstractEquilibrium constants for the formation of Wheland complexes from 1,3,5‐tris(dialkylamino)benzenes and benzhydrylium ions (Ar2CH+) have been determined photometrically in dichloromethane solution at 20 °C. The Lewis basicity of the ring carbons increases in the series trimorpholinobenzene<tripiperidinobenzene<tripyrrolidinobenzene. Wheland complexes, which are formed with equilibrium constants 102<K/M−1<106 in the reactions of triaminobenzenes with carbenium ions, show temperature‐dependent dynamic 1H NMR spectra, due to rapid reverse reactions and recombination at different positions of the triaminobenzenes. Since the rates of the formation of the Wheland complexes are too high to be measured directly, they were calculated as the product of photometrically determined equilibrium constants and the rate constants for the reverse reactions, which were derived from the dynamic 1H NMR spectra. The experimentally determined equilibrium and rate constants were in good agreement with the results of DFT calculations using the SMD solvent model. The calculations show that in all cases the Wheland complexes are thermodynamically more stable than the ammonium ions formed by attack of the benzhydrylium ions at the amino group of the title compounds, which explains the exclusive formation of Wheland complexes in thermodynamically controlled reactions. With nucleophilicity parameters in the range 10<N<15 the triaminobenzenes have comparable nucleophilic reactivities as enamines, silyl ketene acetals as well as stabilized phosphonium and sulfonium ylides
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