Search results for "Ethylene"

Effect of catalyst composition on chain-end-group of polyethylene produced by salen-type complexes of titanium, zirconium, and vanadium

2010

1965

Die Viskositatszahlen von Polyathylenen und Polypropylene wurden in Abhangigkeit von verschiedenen Reaktionsvariablen gemessen. Im untersuchten Bereich wurde mit wachsender Monomerkonzentration eine lineare Zunahme, mit steigender Polymerisationstemperature eine lineare Abnahme der Zη-Werte gefunden. Mit wachsender Katalysatorkonzentration (TiCl3 und Al-organische Verbindungen) nehmen sowohl bei konstantem Al/Ti-Verhaltnis als auch bei konstanter Al-Alkylkonzentration bzw. konstanter TiCl3-konzentration die Viskositatszahlen ab; ihre Veranderung im Bereich kleiner Katalysatorkonzentrationen ist besonders ausgepragt. Die Abhangigkeit der Zη-Werte von der Polymerisationszeit ist gering. Die B…

Optimisation of liquid rubber modified bitumen for road pavements and roofing applications

2020

Abstract Polymer Modified Bitumens (PMBs) are largely used for pavement and roofing membranes applications with Styrene-Butadiene-Styrene Block copolymer (SBS) playing a major role in both markets despite its constantly increasing price due to the rising demand for quality bitumen modifiers. On the other hand, there is an increasing trend of recycling end of life tyres generating Recycled Tyre Rubber (RTR) at affordable price. This investigation aims at engineering a modified bitumen with a combination of Liquid Rubber (LR), a homogeneous blend of 50–70% RTR pre-processed in combination with heavy oils, and a wax denominated Ethylene Bis Stearamide (EBS). In the first phase, the effect of L…

Recycling and Thermomechanical Degradation of LDPE/Modified Clay Nanocomposites

2014

Pegylated interferon α plus ribavirin for the treatment of chronic hepatitis C: A multicentre independent study supported by the Italian Drug Agency

2014

a b s t r a c t Background: Data on the efficacy of Peg-interferon/ribavirin therapy for chronic hepatitis C are mostly derived from treatment of selected patients enrolled in clinical trials. This study aimed to assess the effectiveness of Peg-interferon/ribavirin therapy in “real world” chronic hepatitis C patients in Italy. Methods: Independent observational multicentre study including consecutive patients receiving Peginterferon/ribavirin in the 18 months before (retrospective phase) and after (prospective phase) the start of the study. Results: 4176 patients were eligible. The final study population consisted of 2051 patients in the retrospective and 2073 in the prospective phase. Sust…

Endoluminal Stent-Graft Relining of Visceral Artery Bypass Grafts to Treat Perigraft Seroma

2013

PURPOSE: To describe the endovascular treatment of intra-abdominal perigraft seromas associated with small-caliber expanded polytetrafluoroethylene (ePTFE) grafts. CASE REPORTS: Two patients who underwent hybrid repair of thoracoabdominal aortic aneurysms in which renovisceral bypass grafts were implanted presented with large, symptomatic perigraft seromas. The 5- to 8-mm-diameter ePTFE bypass grafts believed to be involved in the seromas were successfully relined with self-expanding Viabahn stent-grafts in percutaneous procedures. The patients' symptoms were relieved, and imaging follow-up (18 and 10 months, respectively) has shown near complete resorption of the seromas. CONCLUSION: It is…

Chemical composition and particle size influence the toxicity of nanoscale plastic debris and their co-occurring benzo(α)pyrene in the model aquatic …

2021

Little is known about how particle chemical composition and size might influence the toxicity of nanoscale plastic debris (NPD) and their co-occurring chemicals. Herein, we investigate the toxicity of 3 × 1010 particles/L polyethylene (PE, 50 nm), polypropylene (PP, 50 nm), polystyrene (PS, 200 and 600 nm), and polyvinyl chloride (PVC, 200 nm) NPD and their co-occurring benzo(a)pyrene (BaP) to Daphnia magna and Danio rerio. During the 21 days of exposure to PE 50 nm and PS 200 nm, the number of broods produced by D. magna decreased compared to other treatments. Exposure to BaP alone did not produce any effects on the reproduction of the daphnids, however, the mixture of BaP with PS (200 or …

Acyclovir Delivery Matrices Based on Poly(Ethylene Glycol)/Chitosan Semi-Interpenetrating Networks

2007

Abstract Chitosan matrix systems have been studied as potential vehicles for the prolonged release of acyclovir (ACV). The influence of chitosan concentration (from 0.83% to 1.67%) on viscoelastic properties of formulations with and without glyoxal was analyzed. For chitosan‐poly(ethylene glycol) 400 formulations loss modulus ( G ″) are greater than storage modulus ( G ′). This corresponds to the characteristic behavior of nonstructured systems. When glyoxal was added to the chitosan‐poly(ethylene glycol) 400 formulations, gelled matrix was obtained (i.e., G ′ is higher than G ″), except for the lowest chitosan concentration. ACV release rates for the both types of systems, with and without…

The Efficacy of an Experimental Single Solution versus Alternate Use of Multiple Irrigants on Root Dentin Microhardness

2013

The objective of this work was to use fnite element analysis to compare the effect of forces coming to bear on abutments 4.1 or 5.0 mm in diameter connThis study was carried-out to evaluate and compare the efficacy of various irrigants when used singly or in combination on the microhardness of root canal dentin. Study Design: A total of 50 root-halves were randomly divided into 5 groups immediately after the initial baseline microhardness measurements and treated with: Group-1; 7.5%Ethylenediaminetetraaceticacid (EDTA)+ 2.5%sodium hypochlorite (NaOCl), Group-2; 7.5%ethyleneglycol-bis[b-aminoethylether]-N, N,N0,N0-tetraaceticacid (EGTA)+ 2.5%NaOCl, Group-3; 7.5%trans1,2diaminocyclohexane NNN…

Phenoxyamidine Zn and Al Complexes: Synthesis, Characterization, and Use in the Ring-Opening Polymerization of Lactide

2019

International audience; Herein we report the synthesis of new ditopic ligands, which consist of a phenoxy group and N,N,N'trisubstituted amidines linked by a methylene spacer (L1-L4). Their coordination chemistry has been studied/investigated with Zn(II) and Al(III). Alkane elimination route between the phenol-amidine proligands (L1H-L4H) and Et2Zn led to dinuclear complexes [(L1-L4)ZnEt]2 (1a-4a) in which the Zn centers are chelated by phenoxyamidine ligands and bridged through the oxygen atom of the phenoxy groups. Salt metathesis reaction between two equivalents of the sodium amidine phenate L1Na and ZnCl2 led to a bis-chelate chiral spiro-complex (L12Zn) 1a'. Analogous alkane eliminatio…