Search results for "polymer"
showing 10 items of 10504 documents
Synthesis of Biocompatible and Biodegradable Polyamidoamines Microgels via a Simple and Reliable Statistical Approach.
2022
Polyamidoamines (PAAs) are biocompatible and biodegradable polymers with a huge potential as biomaterials for pharmaceutical applications. They are obtained by the step-wise aza-Michael polyaddition of bifunctional or multifunctional amines with bisacrylamides in water. To the best of our knowledge, no synthetic protocols leading to hyperbranched PAAs as well as PAA microgels have been published so far. To fill this gap, a statistical approach was established in this work to fine-tune the aza-Michael polyaddition stoichiometry when a multifunctional co-monomer (bf) is added to a mixture of bifunctional monomers with complementary functions (a2 + b2), possibly even in presence of a monofunct…
Predicting stiffness and strength of birch pulp:Polylactic acid composites
2016
This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40 wt% birch pulp – polylactic acid composite is predicted with X-ray microtomography based finite element modelling, and the results are compared with experiments. Stiffness results differed from experiments by 1–17% . By adding into the models a third material phase representing the interface between the fibres and the matrix, the stress–strain c…
Decomposition rate and biochemical fate of carbon from natural polymers and microplastics in boreal lakes
2022
Microbial mineralization of organic compounds is essential for carbon recycling in food webs. Microbes can decompose terrestrial recalcitrant and semi-recalcitrant polymers such as lignin and cellulose, which are precursors for humus formation. In addition to naturally occurring recalcitrant substrates, microplastics have been found in various aquatic environments. However, microbial utilization of lignin, hemicellulose, and microplastics as carbon sources in freshwaters and their biochemical fate and mineralization rate in freshwaters is poorly understood. To fill this knowledge gap, we investigated the biochemical fate and mineralization rates of several natural and synthetic polymer-deri…
Copolymerization of ethylene with higher 1-olefins over vanadium catalyst supported on Al(i-Bu)3 modified magnesium carrier
2008
Badano proces kopolimeryzacji etylenu z wyższymi 1-olefinami (C6-C12) wobec katalizatora wanadowego (VOCl3) immobilizowanego na nośniku magnezowym MgCl2 (THF) 2 modyfikowanym z zastosowaniem Al(i-Bu) 3. W charakterze aktywatora nośnikowego prekatalizatora wanadowego zastosowano Et2AlCl. Stwierdzono, że aktywność takiego układu katalitycznego jest porównywalna z aktywnością katalizatora z prekursorem wanadowym osadzonym na niemodyfikowanym nośniku magnezowym. Zaobserwowano także, że wprowadzenie komonomeru do środowiska reakcji powoduje niewielkie zmniejszenie wydajności procesu w porównaniu z homopolimeryzacją etylenu, postępującą w miarę wzrostu stężenia komonomeru w środowisku reakcji. Do…
Magneto-structural correlations in discrete $Mn^{II}‐W^V$ cyano‐bridged assemblies with polyimine ligands
2010
We present the magneto-structural correlations for two novel discrete cyano-bridged assemblies based on cationic complexes of manganese(II) with diimine ligands and octacyanotungstate(V) ions. The crystal structure of [Mn II (terpy)(dmf)-(H 2 O) 2 ][Mn II (terpy)(H 2 O)(dmf)(μ-NC)W V (CN) 7 ] 2· 6H 2 O (1) (terpy = 2,2';6',2"-terpyridine, dmf = dimethylformamide) contains dinuclear {Mn II W V } - cyano-bridged anions, while the crystal structure of [Mn II (phen) 3 ] 2 [MnII(phen) 2 (μ-NC) 2 -W V (CN) 6 ] 2 (ClO 4 ) 2 ·9H 2 O (2) (phen = 1,10-phenanthroline) is built of tetranuclear {Mn II 2 W V 2} 2- square anions. Intramolecular Mn-W magnetic interactions through the cyano bridges are repr…
Tolerance, Adaptation, and Cell Response Elicited by Micromonospora sp. Facing Tellurite Toxicity: A Biological and Physical-Chemical Characterization
2022
The intense use of tellurium (Te) in industrial applications, along with the improper disposal of Te-derivatives, is causing their accumulation in the environment, where oxyanion tellurite (TeO32−) is the most soluble, bioavailable, and toxic Te-species. On the other hand, tellurium is a rare metalloid element whose natural supply will end shortly with possible economic and technological effects. Thus, Te-containing waste represents the source from which Te should be recycled and recovered. Among the explored strategies, the microbial TeO32− biotransformation into less toxic Te-species is the most appropriate concerning the circular economy. Actinomycetes are ideal candidates in…
Amorphous Polyphosphate and Ca‐Carbonate Nanoparticles Improve the Self‐Healing Properties of both Technical and Medical Cements
2020
Cement is used both as a construction material and for medical applications. Previously, it has been shown that the physiological polymer inorganic polyphosphate (polyP) is morphogenetically active in regeneration of skin, bone, and cartilage. The present study investigates the question if this polymer is also a suitable additive to improve the self-healing capacity not only of construction cement but also of inorganic bone void fillers. For the application in the cement, two different polyP-based amorphous nanoparticles (NP) are prepared, amorphous Ca-polyP NP and amorphous Ca-carbonate (ACC) NP. The particles are integrated into poly(methyl methacrylate) in a concentration ratio of 1:10. …
Anti-senescence and Anti-inflammatory Effects of the C-terminal Moiety of PTHrP Peptides in OA Osteoblasts.
2016
Osteoarthritis (OA) is characterized by degenerative changes in the whole joint leading to physical disability in the elderly population. This condition is associated with altered bone metabolism in subchondral areas suggesting that therapeutic strategies aimed at modifying bone cell metabolism may be of interest. We have investigated the effects of several parathyroid hormone-related protein (PTHrP)-derived peptides (1-37): (N-terminal), (107-111) and (107-139) (C-terminal) on senescence features induced by inflammatory stress in human OA osteoblasts. Incubation of these primary cells with interleukin(IL)-1β led to an increased expression of senescence markers senescence-associated-β-galac…
Transcriptional profiles from patients with dystrophinopathies and limb girdle muscular dystrophies as determined by qRT-PCR.
2003
Mutations in genes coding for the dystrophin-glycoprotein complex (DGC) cause inherited muscular dystrophies (MD), including Morbus Duchenne (DMD) and M. Becker (BMB) as well as limb-girdle muscular dystrophies (LGMD). New insights into the pathophysiology of the dystrophic muscle, the identification of compensatory mechanisms and additional proteins interacting with dystrophin are essential for developing new treatments. In order to define molecular mechanisms induced by lack of dystrophin and the subsequent counter-regulatory transcriptional response of degenerating muscle fibres, we have investigated the mRNA expression of 19 functionally linked genes in biopsies of patients with MD by m…
HLA-B27-restricted cytotoxic T lymphocyte responses to arthritogenic enterobacteria or self-antigens are dominated by closely related TCRBV gene segm…
1996
Identification of the T-cell receptors (TCR) used by synovial cytotoxic T lymphocytes (CTL) of patients with reactive arthritis (ReA) may be crucial to better understanding the pathogenetic mechanism underlying the HLA-B27 association of spondylarthropathies. The authors, therefore, sequenced 25 TCRB chains from HLA-B27-restricted CD8+ CTL clones and two clonal lines specific for self- or Yersinia enterocolitica antigen isolated from synovial fluids of 3 HLA-B27+ patients with ReA and PBL of one healthy HLA-B27+ individual. Fourteen non-HLA-B27-restricted CTL served as controls. Both autoreactive and Y. enterocolitica specific HLA-B27-restricted CTL used a highly limited set of VB genes wit…