Search results for "Lene"

Mechanical properties of recycled polyethylene ecocomposites filled with natural organic fillers

2006

The use of natural organic fillers in addition to postconsumer recycled polymers is getting a growing interest during the last years; this is due to many advantages they can provide in terms of cost, aesthetic properties, environmental impact. In this work, several types of wood flour (differing each other with regard to production source and particle size) were added to a recycled polyethylene coming from films for greenhouses and the effects of filler type, content, and size were investigated. Investigation was then focused on the improvement of mechanical properties, through the addition of polar copolymers (ethylene-co-acrylic acid, ethylene-vinyl acetate) and a maleic anhydride-grafted…

Progression of Diiminopyridines: From Single Application to Catalytic Versatility

2015

Diiminopyridyl metal complexes, first characterized several decades ago, found practical application in 1998 when they were used as precatalysts in coordinative ethylene polymerization. This discovery contributed to the so-called postmetallocene revolution and triggered the large-scale experimental and theoretical research aimed at understanding diversified diiminopyridine chemistry. The results of this quest, some of which were intriguing and difficult to anticipate, are discussed and summarized in the current Review.

Kritiskā fūzijas frekvence un tīklenes apgaismojums

2020

Maģistra darbs ir uzrakstīts latviešu valodā uz 40 lapaspusēm. Tas satur 27 attēlus, 4 tabulas un ietver atsauces uz 38 literatūras avotiem. Mērķis: noskaidrot tīklenes apgaismojuma izmaiņas ietekmi uz kritiskās flikera frekvences slieksni. Metode: tiek noteikts dalībnieku kritiskās fūzijas frekvences slieksnis ar frekvences samazināšanas metodi. Tīklenes apgaismojuma maiņai tiek izmantoti oklūderi ar trīs dažāda izmēra atvērumiem. Rezultāti: palielinoties oklūdera diametram, tiek iegūts slieksnis pie augstākām frekvencēm.

Sustainable Recycling of Insoluble Rust Waste for the Synthesis of Iron-Containing Perovskite-Type Catalysts

2019

Insoluble rust waste from the scraping of rusted iron-containing materials represents a cheap, eco-friendly, and available source of iron. LaFeO3 perovskite-type powders were successfully prepared by solution combustion synthesis using rust waste from an electricity transmission tower manufacturer. Solution combustion synthesis enabled introduction of this insoluble iron precursor directly into the final product, bypassing complex extraction procedures. Catalytic activity in the propylene oxidation of the waste-derived LaFeO3 with stoichiometric Fe/La ratio was almost identical to the commercial iron nitrate-derived LaFeO3 , thus demonstrating the viability of this recycling solution. The a…

Nature of Bonding in Group 13 Dimetallenes: a Delicate Balance between Singlet Diradical Character and Closed Shell Interactions

2010

The nature of metal−metal bonding in group 13 dimetallenes REER (E = Al, Ga, In, Tl; R = H, Me, tBu, Ph) was investigated by use of quantum chemical methods that include HF, second order Møller−Plesset perturbation theory (MP2), coupled cluster (CCSD(T)), complete active space with (CASPT2) and without (CAS) second order perturbation theory, and two density functionals, namely, B3LYP and M06-2X. The results show that the metal−metal interaction in group 13 dimetallenes stems almost exclusively from static and dynamic electron correlation effects: both dialuminenes and digallenes have an important singlet diradical component in their wave function, whereas the bonding in the heavier diindene…

Metal salen complexes as ethylene polymerization catalysts - effect of catalytic system composition on its activity and properties of polymerization …

2008

Zsyntetyzowano i zastosowano [po aktywacji metyloaluminoksanem (MAO) lub Et2AlCl] w charakterze katalizatorów niskociśnieniowej polimeryzacji etylenu serię salenowych kompleksów metali przejściowych różniących się rodzajem atomu centralnego (M=Ti, Zr lub V) i budową chemiczną ligandu (schemat A). Stwierdzono, że salenowe kompleksy cyrkonu są aktywne w polimeryzacji jedynie wówczas, gdy aktywator stanowi MAO, natomiast kompleksy tytanu i wanadu są aktywniejsze w przypadku gdy kokatalizatorem jest typowy związek glinoorganiczny - dietylochloroglin. Aktywność kompleksów w układzie z Et2AlCl zmienia się w szeregu V>Ti>>Zr?0, podczas gdy w odniesieniu do kompleksów aktywowanych MAO maleje ona w …

Brief an Johann Gottfried Herder

1797

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 stentgrafts 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 …

Pyrolytic formation of polycyclic aromatic hydrocarbons from sesquiterpenes

2012

Author's version of an article in the journal: Food Chemistry. Also available from the publisher at: http://dx.doi.org/10.1016/j.foodchem.2012.06.033 The products of the pyrolysis of four sesquiterpenes, β-caryophyllene, α-cedrene, longifolene and valencene, have been examined. Pyrolysis was carried out at 300, 400 and 500 °C, the products determined by GC–MS and then examined for similarities and differences using multivariate data analysis. Analysis showed that longifolene was most resistant and caryophyllene least resistant to pyrolysis with cedrene and valencene occupying intermediate positions. While the compounds were largely unchanged at 300 °C, polycyclic aromatic hydrocarbons (PAHs…

Fibre fragment distribution in a single-fibre composite tension test

2001

Abstract Single fibre fragmentation tests are performed for brittle fibres with Weibull strength distribution and different surface treatments. The fragmentation process is modelled and closed-form expressions for break spacing distribution are obtained. The model accounts for the effect of finite fibre length on the initial fragmentation as well as for break interaction on the advanced fragmentation stage. It is assumed that the exclusion zone due to fibre–matrix interface failure and stress recovery in the fibre is linearly dependent on the applied load. This assumption is validated experimentally. The derived theoretical average fragment length dependence on applied load is used to deter…