Search results for "opening"
showing 10 items of 154 documents
Highly Syndiotactic or Isotactic Polyhydroxyalkanoates by Ligand-Controlled Yttrium-Catalyzed Stereoselective Ring-Opening Polymerization of Function…
2017
International audience; Reported herein is the first stereoselective controlled ROP of a specific family of racemic functional β-lactones, namely 4-alkoxymethylene-β-propiolactones (BPL(OR) s). This process is catalyzed by an yttrium complex stabilized by a nonchiral tetradentate amino alkoxy bisphenolate ligand _ONOO(R'2) ₍2-) , which features both a good activity and a high degree of control over the molar masses of the resulting functional poly(3-hydroxyalkanoate)s. A simple modification of the R' substituents in ortho and para position on the ligand platform allows for a complete reversal from virtually pure syndioselectivity (Ps up to 0.91 with R'=cumyl) to very high isoselectivity (Pi…
One-pot synthesis of fluorinated 2-amino-pyrimidine-N-oxides. Competing pathways in the four-atom side-chain rearrangements of 1,2,4-oxadiazoles
2006
Abstract Trifluoromethylated 2-amino-pyrimidine N-oxides have been synthesized by reaction of the 3-amino-5-methyl-1,2,4-oxadiazole with trifluoromethyl-β-diketones in the presence of perchloric acid, followed by hydrolysis. In this ring-to-ring transformation an initial formation of (unisolated) 1,2,4-oxadiazole-pyrimidinium salts, and subsequent ring-opening at the oxadiazole moiety occurs. Isolation of 2-(hydroxyamino)-pyrimidine from the reaction mixture evidenced the presence of a competing pathway where the N(4) nitrogen of the oxadiazole is involved in the formation of a regioisomeric pyrimidinium salt. The effect of the trifluoromethyl group on the product distribution is discussed.…
Nestriktās matemātikas morfoloģijas operatori: teorijas pamati un operatoru realizācija konkrētiem konjuktoru-implikatoru pāriem
2021
Maģistra darbā apskatīti matemātiskās morfoloģijas pamatoperatoru - dilācija, erozija, atvēršana, slēgšana - paplašinājumi nestriktās kopās. Vispārīga nestrikta morfoloģijas operatora definīcija realizēta konkrētiem konjunktoru-implikātoru pāriem. Operatoru realizācijā par konjunktoriem izvēlētas minimuma, reizinājuma un Lukasieviča t-normas un par implikatoriem - tām atbilstošie rezidiji un Klīnī-Dinesa implikācija. Konkrētie konjunktoru-implikatoru pāriem iegūtie operatori ilustrēti ar vizuāliem piemēriem, to realizācijai izstrādāta arī lietojumprogramma. Veikta iegūto rezultātu analīze.
Riapertura di procedimenti interni, margine di apprezzamento, consensus europeo
2021
The contribution comments on separate opinions rendered by Judge Pinto dealing with the reopening of domestic civil processes in which violations of ECHR have occurred.
Arthroscopic approach for treating a pigmented villonodular sinovitis of TMJ. A case report
2017
The present report describes the case of a 29-year-old man referred to our service for TMJ pain and progressive reduction of the mouth opening. Differential diagnostics included rheumatologic diseases, monoarthritis and intraarticular lumps. In this line, a face CT scan and a MRI of TMJ were carried out in order to ensure a proper diagnosis. These tests showed a solid lesion into the joint cavity. In view of that, we decided to perform a diagnostic and therapeutic arthroscopy of TMJ. Histopathological studies confirmed the diagnosis of pigmented villonodular synovitis. The main aim of this report is to describe this rare syndrome with the goal of proposing suitable treatments. Moreover, we …
Facile and efficient chemical functionalization of aliphatic polyesters by cross metathesis
2016
International audience; An effective preparation of new tailor-made macromolecular materials via a combination of two (atom-efficient) catalytic transformations is reported. First, new aliphatic polyesters with alternated composition have been prepared using a salen aluminum catalyst system. Next, the pendant vinyl moieties in those copolymers have been selectively transformed into various functional groups by metathesis in the presence of homogeneous Grubbs catalysts. The latter metathesis reaction has been optimized in terms of catalytic activity and selectivity, to define the conditions for an effective and safe procedure that does not affect the macromolecular architecture. All polymer …
Silseskwioksany i ich zastosowanie w syntezie materiałów polimerowych
2015
Artykuł stanowi przegląd literatury dotyczącej syntezy oraz charakterystyki materiałów polimerowych zawierających silseskwioksany (POSS). Przedstawiono metody otrzymywania hybrydowych materiałów polimerowych z udziałem funkcjonalizowanych POSS na drodze click chemistry, polikondensacji, poliaddycji, metatezy z otwarciem pierścienia ipolimeryzacji rodnikowej zarówno konwencjonalnej, jak i kontrolowanej (ATRP).
Polysarcosine-Based Lipids: From Lipopolypeptoid Micelles to Stealth-Like Lipids in Langmuir Blodgett Monolayers.
2016
Amphiphiles and, in particular, PEGylated lipids or alkyl ethers represent an important class of non-ionic surfactants and have become key ingredients for long-circulating (“stealth”) liposomes. While poly-(ethylene glycol) (PEG) can be considered the gold standard for stealth-like materials, it is known to be neither a bio-based nor biodegradable material. In contrast to PEG, polysarcosine (PSar) is based on the endogenous amino acid sarcosine (N-methylated glycine), but has also demonstrated stealth-like properties in vitro, as well as in vivo. In this respect, we report on the synthesis and characterization of polysarcosine based lipids with C14 and C18 hydrocarbon chains and their end g…
Low-temperature Molecular Layer Deposition Using Monofunctional Aromatic Precursors and Ozone-based Ring Opening Reactions
2017
Molecular layer deposition (MLD) is an increasingly used deposition technique for producing thin coatings consisting of purely organic or hybrid inorganic–organic materials. When organic materials are prepared, low deposition temperatures are often required to avoid decomposition, thus causing problems with low vapor pressure precursors. Monofunctional compounds have higher vapor pressures than traditional bi- or trifunctional MLD precursors, but do not offer the required functional groups for continuing the MLD growth in subsequent deposition cycles. In this study, we have used high vapor pressure monofunctional aromatic precursors in combination with ozone-triggered ring-opening reactions…
Dimmi che sigla guardi e ti dirò chi sei
2020
Opening credits, sequences which accompany each episode of a television series, have radically changed over time. From being brief and marginal texts, edited with low care e watched with a low level of attention, they have become artistic and elegant sequences, often created by specialized companies to keep the viewer’s eyes glued to the screen. The opening credits still keep their original function – giving information about the programme – but nowadays they achieve their goal in various ways. The main titles refer to the content of the series using different tones, thereby setting a particular mood that prepares the viewer for the show. In this article, we will try to focus on these diffe…