Search results for "Esteri"
showing 10 items of 220 documents
Degradation and Recycling of Films Based on Biodegradable Polymers: A Short Review
2019
The environmental performance of biodegradable materials has attracted attention from the academic and the industrial research over the recent years. Currently, degradation behavior and possible recyclability features, as well as actual recycling paths of such systems, are crucial to give them both durability and eco-sustainability. This paper presents a review of the degradation behaviour of biodegradable polymers and related composites, with particular concern for multi-layer films. The processing of biodegradable polymeric films and the manufacturing and properties of multilayer films based on biodegradable polymers will be discussed. The results and data collected show that: poly-lactic…
PET/PEN Blends of Industrial Interest as Barrier Materials. Part I. Many-Scale Molecular Modeling of PET/PEN Blends
2006
Mesoscale molecular simulations, based on parameters obtained through atomistic molecular dynamics and Monte Carlo calculations, have been used for modeling and predicting the behavior of PET/PEN blends. Different simulations have been performed in order to study and compare pure homopolymer blends with blends characterized by the presence of PET/PEN block copolymers acting as compatibilizer. A many-scale molecular modeling strategy was devised to evaluate PET/PEN blend characteristics, simulate phase segregation in pure PET/PEN blends, and demonstrate the improvement of miscibility due to the presence of the transesterification reaction products. The behavior of distribution densities and …
Distributed feedback lasing in cellulose films
2013
Cellulose derivatives, because of their molecular structure and chirality, can self-assemble to form spatially periodic cholesteric liquid crystal phases. We have synthesized and produced solid cross-linked cholesteric cellulose based films optimized to provide high reflectivity. Since these films are self-assembled photonic bandgap materials, they may be expected to show distributed feedback lasing. By doping samples with fluorescent dyes and optically pumping thin films of these materials, we were able to demonstrate, to the best of our knowledge, for the first time, mirrorless band-edge lasing in cellulose derivatives.
Novel Functionality of Lithium-Impregnated Titania as Nanocatalyst
2019
The present work incorporates the synthesis of a multifunctional catalyst for the transesterification of waste cooking oil (WCO) to biodiesel and recovery of rare earth elements (REEs). For this purpose, TiO2 nanoparticles and TiO2 doped with lithium ions were prepared. The influence of lithium ions on the catalytic performance of TiO2 was attained by impregnation of the different molar ratios of lithium hydroxide to bare TiO2. Then each catalyst was screened for catalytic conversion of WCO to fatty acid methyl ester (FAME) and also for REEs recovery. All synthesized materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Transmission electron microsc…
Use of amino–polycarboxylic chelating agents for the sequestration of (CH3)Hg+ ion in aqueous solution
2012
Among the mercury organic derivatives, mono-methylmercury (MMHg) is by far the most toxic form of mercury because of its high capacity to enter biological membranes and accumulate in living organisms [1], as shown by the biomagnification factors: ~104 from water to edible shell-fish (mussels), and 106 –108 from water to big fishes (e.g. tuna fish) at the top of food chain [2]. The presence of complexing agents in the environment, which form soluble complex species with MMHg, favours the mobility of the ion in the aquatic ecosystems. Among anthropogenic complexing molecules, the most used ones are the aminopolycarboxylic chelating agents (usually called with the acronym APC) which are employ…
Ķīmiskā sastāva izvērtējums svaigi spiestās augu eļļās ar gāzu hromatogrāfijas-masspektrometrijas metodēm
2017
Literatūras apskata ietvaros apkopota informācija par piesātinātajām, mononepiesātinātām un polinepiesātinātām taukskābēm, to noteikšanu svaigi spiestās un komerciāli pieejamās augu eļļās, pielietojot gāzu hromatogrāfijas un masspektrometrijas metodes. Eksperimentālajā daļā tika izstrādātas metodes eļļu taukskābju sastāva izvērtēšanai un noteikšanai ar dažādām polidimetilsiloksānu kapilārajām kolonnām kā arī dažādiem detektoriem – liesmas jonizācijas un masspektrometrisko. Praktiski tika izvērtēts 5 svaigi spiestu paraugu, kā arī 4 komerciāli pieejamo eļļu taukskābju sastāvs.
Isostructural Dinuclear Phenoxo-/Acetato-Bridged Manganese(II), Cobalt(II), and Zinc(II) Complexes with Labile Sites: Kinetics of Transesterification…
2012
Using the dinucleating phenol-based ligand 2,6-bis[3-(pyridin-2-yl)pyrazol-1-ylmethyl]-4-methylphenol] (HL(2)), in its deprotonated form, the six new dinuclear complexes [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][PF(6)] (M = Mn (2a), Co (3a), Zn (4a)) and [M(II)(2)(L(2))(μ-O(2)CMe)(2)(MeCN)(2)][BPh(4)] (M = Mn (2b), Co (3b), Zn (4b)) have been synthesized. Crystallographic analyses on 2b·2MeCN, 3b·2MeCN, and 4b·2MeCN reveal that these complexes have closely similar μ-phenoxo bis(μ-carboxylato) structures. The physicochemical properties (absorption and ESI-MS spectral data, 2a,b, 3a,b, and 4a,b; (1)H NMR, 4a,b) of the cations of 2a-4a are identical with those of 2b-4b. Each metal ion is termina…
Reactive blending of a functionalized polyethylene with a semiflexible liquid crystalline copolyester
1996
Reactive blends (50/50 w/w) of a low molar mass polyethylene containing free carboxylic groups (PEox) and a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2, by Eniricerche) have been prepared at 240 degrees C in a Brabender mixer, in the presence of Ti(OBu)(4) catalyst, for different mixing times (15, 60, and 120 min). In order to prove the formation of a PE-g-SBH copolymer, the blends have been fractionated by successive extractions with boiling toluene and xylene. The soluble fractions and the residues have been analyzed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG and DTG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM)…
Helicates with Ether-Substituted Catechol Esters as Ligands
2020
European journal of organic chemistry 2020(32), 5161-5172 (2020). doi:10.1002/ejoc.202000843
Ģimenes hiperholesterinēmijas prevalence starp pacientiem ar koronāro artēriju aterosklerozi
2018
Ievads: Tiek uzskatīts, ka vienam no 200-250 cilvēkiem ir heterozigota ģimenes hiperholesterinēmija (ĢH). Pacientiem ar ĢH ir ievērojami paaugstināts zema blīvuma lipoproteīna holesterīna (ZBLH) līmenis, kas savukārt noved pie agrīnas aterosklerozes attīstības. Aterosklerozei attīstoties koronārajās artērijās, pieaug mirstība no koronārās sirds slimības. Pacientiem ar ĢH ZBLH līmenis tipiski ir >5 mmol/l, taču lipīdus pazeminošās terapijas fonā, tas var samazināties zem 5 mmol/l, kas apgrūtina ĢH diagnozes atpazīšanu. Mērķis: Noskaidrot potenciālo ģimenes hiperholesterinēmijas izplatību starp Latvijas Kardioloģijas centrā (LKC) stacionētiem pacientiem ar pierādītu koronāro artēriju ateroskl…