Search results for "Polyethylene"

Timing effect of intramyocardial hydrogel injection for positively impacting left ventricular remodeling after myocardial infarction

2015

Intramyocardial injection of various injectable hydrogel materials has shown benefit in positively impacting the course of left ventricular (LV) remodeling after myocardial infarction (MI). However, since LV remodeling is a complex, time dependent process, the most efficacious time of hydrogel injection is not clear. In this study, we injected a relatively stiff, thermoresponsive and bioabsorbable hydrogel in rat hearts at 3 different time points - immediately after MI (IM), 3 d post-MI (3D), and 2 w post-MI (2W), corresponding to the beginnings of the necrotic, fibrotic and chronic remodeling phases. The employed left anterior descending coronary artery ligation model showed expected infar…

Enhancing Performance of a Bis(arylimino)pyridine‐Iron Precatalyst for Ethylene Polymerization by Substitution with a 2,4‐Bis(4,4′‐dimethoxybenzhydry…

2021

A series of unsymmetrical 2-(2,4-bis(bis(4-methoxyphenyl)methyl)-6-MeC6H2N)-6-(1-(arylimino)ethyl)pyridine-iron halides has been synthesized and characterized. The molecular structure of two representative species was determined by the single-crystal X-ray diffraction. Activated with either MAO or MMAO, the precatalysts displayed high activity, reaching 2.19×107 g PE (mol Fe)−1 h−1 at 60 °C in ethylene polymerization. The microstructural analysis of the polymers obtained indicates highly linear polyethylene containing a vinyl chain end.

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

2020

Ethylene polymerization by the thermally unique 1-[2-(bis(4-fluoro phenyl)methyl)-4,6- dimethylphenylimino]-2-aryliminoacenaphthylnickel precursors

2015

A series of 1-[2-(bis(4-fluorophenyl)methyl)-4,6-dimethylphenylimino]-2-aryliminoacenaphthylene derivatives together with the corresponding nickel bromide complexes was synthesized and characterized. Representative complexes C2 and C5 were characterized by the single-crystal X-ray diffraction, revealing a distorted tetrahedral geometry. Upon activation with either methylaluminoxane (MAO) or ethylaluminum sesquichloride (EASC), all nickel complexes exhibited high activities towards ethylene polymerization, producing polyethylene with a relatively low degree of branching and narrow polydispersity. Complex C1 maintained good activity at elevated reaction temperatures, which indicates significa…

Enhancing performance of α‐diiminonickel precatalyst for ethylene polymerization by substitution with the 2,4‐bis(4,4'‐dimethoxybenzhydryl)‐6‐methylp…

2020

High activities in ethylene polymerization predetermine α‐diiminonickel precatalysts for potential industrial applications. In our study, we have synthesized and characterized a series of unsymmetrical 1‐(2,4‐bis(4,4′‐dimethoxybenzhydryl)‐6‐MeC6H2N)‐2‐arylimino‐acenaphthylene nickel(II) halides. The single‐crystal X‐ray diffraction study of representative compounds reveals distorted tetrahedral geometry. On activation with either Me2AlCl or modified methylaluminoxane, these nickel complexes exhibit high activities of the order of 106 g of PE (mol of Ni)−1 h−1 and produce polyethylene of generic application characterized by high molecular weight, narrow molecular weight distribution, and mod…

Bridging rigidity and flexibility : modulation of supramolecular hydrogels by metal complexation

2021

The combination of complementary, noncovalent interactions is a key principle for the design of multistimuli responsive hydrogels. In this work, an amphiphilic peptide, supramacromolecular hydrogelator which combines metal-ligand coordination induced gelation and thermoresponsive toughening is reported. Following a modular approach, the incorporation of the triphenylalanine sequence FFF into a structural (C3EG ) and a terpyridine-functionalized (C3Tpy ) C3 -symmetric monomer enables their statistical copolymerization into self-assembled, 1D nanorods in water, as investigated by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the presence of a terpyridine …

Skābekļa atomu saturošie imidazolija sāļi kondensācijas reakcijās

2021

Skābekļa atomu saturošie imidazolija sāļi kondensācijas reakcijās. Gradovska L., darba vadītāji Dr.h.ķīm., prof. Zicmanis A., Dr.chem. Baķis E. Maģistra darbs, 59 lappuses, 31 attēls, 5 tabulas, 43 literatūras avoti, 1 pielikums. Latviešu valodā. Literatūras apskatā apkopota informācija par biežāk aprakstītajiem jonu šķidrumiem un polietilēnglikola funkcionalizētajem jonu šķidrumiem, to iegūšanu un izmantošanas iespējām organiskajā katalīzē. Eksperimentālajā daļā sintezēti polietilēnglikola, spirtu un alkilvirkņu funkcionalizētie imidazolija rindas jonu šķidrumi, kuri izmantoti kā katalizatori un reakcijas vide Knēvenāgela kondensācijā. Reakcijas konversija atkarībā no laika novērtēta, izma…

Influence of cryogenic grinding on properties of a self-emulsifying formulation

2003

Abstract Recently, self-emulsifying drug delivery systems (SEDDS) have been developed as a method to deliver lipophilic drugs. Gelucire® 44/14 is an excipient, from the lauroyl macrogolglycerides family, producing a fine oil-in-water emulsion when introduced into an aqueous phase under gentle agitation as SEDDS, improving thereby solubility of poorly water-soluble drugs and their bioavailability. The aims of this study were to process Gelucire® 44/14 into a powder by cryogenic grinding to produce solid oral dosage forms and to investigate influence of this process on different properties of a formulation made of Gelucire® 44/14 and ketoprofen (90/10). Cryogenic grinding produced Gelucire® 4…

Experimental Investigation for Local Tank Inflow Model

2014

In the present paper the effect of private roof tanks and of the float valve characteristics on apparent losses due to water meter errors was investigated via an experimental study. The tests were carried out at the Environmental Hydraulic Laboratory of the University of Enna (Italy), on a high-density polyethylene (HDPE 100 PN16) looped distribution network. The experimental results showed that network pressure plays an important role in the characterisation of the floating ball valve emitter law, but the tank operating condition is the most relevant aspect to be considered mainly for water meter error evaluation. (C) 2014 The Authors. Published by Elsevier Ltd.

Impact of contact lens material and design on the ocular surface.

2018

BACKGROUND: To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content. METHODS: The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry. RESULTS: The nesofilcon A was shown to be the thinnest lens…