1,721,150 research outputs found
Complexes of polydentate ligands as stereoselective catalysts for the polymerization of alpha-olefins and the ring opening polymerization of cyclic esters
No full textHalf-metallocene catalysts:structure and polymerization mechanism for the preparation of syndiotactic polystyrene and stereoregular poly(dienes)
No full text“Syndiotactic-specific polymerization of styrene: Catalyst structure and polymerization mechanism”
No full textMetal complexes as fluorescent probes for sensing biologically relevant gas molecules
Full text linkThe last decades have seen a marked escalation in interest in the biology of naturally occurring gases. Examples of the most significant of these gases are nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S). All of them feature a number of physiological and/or pathophysiological functions within the human body. For example, NO regulates vasodilatation in the circulatory system and long-term potentiation in the brain. CO modulates vasorelaxation, vascular smooth muscle cell growth and tissue injury. H2S relaxes vascular smooth muscle and inhibits smooth muscle cell proliferation. In addition, it acts as neuromodulator in the central nervous system. Furthermore, it is also well acknowledged that all of them are differently associated with various human diseases. However, for the advancement of our understanding of the physiological and pathological roles played by these signal transductors, there is a pressing need for methods allowing their detection in both aqueous and gaseous media. The aim of this review is to highlight the recent developments in the field of metal complexes as fluorescent probes for the detection of gasotransmitters and to provide a general overview of fluorescent sensors implemented so far for NO, CO and H2S
Polymerization of some hydrocarbon monomers in the presence of transition organometallic catalysts
No full text“Processo di estrazione del licopene puro dagli scarti della lavorazione del pomodoro con acqua potabile come liquido estraente”.
No full textL'invenzione riguarda un nuovo processo per l’estrazione del licopene ad elevato grado di purezza dagli scarti della lavorazione del pomodoro, mediante l’uso di una nuova tecnologia di estrazione solido-liquido dinamica. Nella fase estrattiva viene impiegata acqua potabile come liquido estraente in modo tale da abbassare il costo totale dell’intero processo di recupero del licopene e da consentire un facile riciclo del materiale esausto. Il licopene ottenuto nel processo messo a punto è ad un alto grado di purezza (398%)
Isotactic-specific polymerization of propene with an iron-based catalyst: polymer end groups and regiochemistry of propagation
No full textPrevailingly isotactic poly(propylene) samples were prepared with a homogeneous catalytic
system based on a bis(imino)pyridyl Fe(II) derivative and methylaluminoxane. The polymer microstructure
is in agreement with Bernoullian statistics of dyad formation, implicating a "chain-end mechanism of steric
control. The latter is operative even at polymerization temperatures as high as +50"C. NMR analysis of polymer
end groups indicates that chain growth proceeds via 2,l monomer insertion. The last two findings are
unprecedented for isotactic-specific polymerization of propene and are reasonably related to each other
Polymerization of propene with Ni(II) -diimine cataltsts: evidence of a dual mechanism of steric control
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