Search results for "POLYETHYLENE"
showing 10 items of 809 documents
Surface Modification of Polysaccharide-Based Nanoparticles with PEG and Dextran and the Effects on Immune Cell Binding and Stimulatory Characteristic…
2017
Surface modifications of nanoparticles can alter their physical and biological properties significantly. They effect particle aggregation, circulation times, and cellular uptake. This is particularly critical for the interaction with primary immune cells due to their important role in particle processing. We can show that the introduction of a hydrophilic PEG layer on the surface of the polysaccharide-based nanoparticles prevents unwanted aggregation under physiological conditions and decreases unspecific cell uptake in different primary immune cell types. The opposite effect can be observed with a parallel-performed introduction of a layer of low molecular weight dextran (3.5 and 5 kDa) on…
Effect of bioglass on growth and biomineralization of SaOS-2 cells in hydrogel after 3D cell bioprinting.
2014
We investigated the effect of bioglass (bioactive glass) on growth and mineralization of bone-related SaOS-2 cells, encapsulated into a printable and biodegradable alginate/gelatine hydrogel. The hydrogel was supplemented either with polyphosphate (polyP), administered as polyP • Ca2+-complex, or silica, or as biosilica that had been enzymatically prepared from ortho-silicate by silicatein. These hydrogels, together with SaOS-2 cells, were bioprinted to computer-designed scaffolds. The results revealed that bioglass (nano)particles, with a size of 55 nm and a molar ratio of SiO2 : CaO : P2O5 of 55 : 40 : 5, did not affect the growth of the encapsulated cells. If silica, biosilica, or polyP …
Edible Arabinoxylan-Based Films. 1. Effects of Lipid Type on Water Vapor Permeability, Film Structure, and Other Physical Characteristics
2002
Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was obser…
The chloro‐substituent enhances performance of 2,4‐bis (imino)pyridylchromium catalysts yielding highly linear polyethylene
2020
The five unsymmetrical 2‐[1‐(2,4‐dibenzhydryl‐6‐chlorophenylimino)ethyl]‐6‐[1‐(arylimino)ethyl]pyridine compounds (aryl: 2,6‐Me2Ph L1 , 2,6‐Et2Ph L2 , 2,6‐i Pr2Ph L3 , 2,4,6‐Me3Ph L4 and 2,6‐Et2–4‐MePh L5 ) were prepared and characterized with FT‐IR and 1H/13C NMR spectroscopy as well as elemental analysis. The treatment of L1 – L5 with CrCl3·3THF affords the corresponding chromium chloride complexes (Cr1 – Cr5 ) in excellent yields. The molecular structures of Cr2 and Cr3 characterized by X‐ray diffraction show a distorted octahedral geometry with three nitrogen atoms and three chlorine atoms around the metal center. On activation with either MAO or MMAO, Cr1 – Cr5 collectively display hig…
Supramolecular PEG-co-oligo(p-benzamide)s prepared on a peptide synthesizer.
2007
An automated synthesis protocol has been developed for the preparation of oligo(p-benzamide)s on solid support using a commercial peptide synthesizer employing a variation of standard Fmoc chemistry. Bis(trichloromethyl carbonate) in NMP was used to activate the aromatic carboxylic acids for acylation of secondary aromatic amines on solid support. N-Protected hepta(p-benzamide) was automatically prepared on solid support and manually converted to a solid supported block co-oligomer by attaching a poly(ethylene glycol) chain. Cleavage from the support could be achieved with minimal loss of the p-methoxybenzyl N-protective group. While the N-protected block co-oligomer was molecularly dissolv…
High-resolution pyrolysis–gas chromatography with a movable reaction zone
1997
Abstract A new device was constructed for pyrolysis–gas chromatography and it was laboratory tested. The device enables the thermal degradation of polymers inside a capillary pre-column and transfer of the reaction zone into a column oven. The pyrolysis procedure described protects the thermally sensitive compounds prior to pyrolysis, prevents the process of irreversible condensation of high-boiling pyrolysis products during the chromatographic process and eliminates extracolumn effects on the peak broadening.
Microporous hypercrosslinked polystyrene Styrosorb as a restricted access packing in sample clean-up for high performance liquid chromatography. Part…
1993
Styrosorb is a beaded microporous polystyrene with particle sizes between 2 and 4 μm. In spite of hypercrosslinkage the material was seen to swell in organic solvents. The native material is functionalized with Tris-groups at the outer surface of the particles. The average pore diameter was determined as 1.45±0.3 nm from size exclusion data using polystyrene and polyethylene standards in THF. The reversed phase behavior of the restricted access phase Styrosorb was investigated by injection of two test mixtures. Mixture I contained five aromatic amines, mixture II consisted of AmperozideR and four related compounds. The optimum range of mobile phase composition was assessed so that analytes …
Alkaline haematin D-575, a new tool for the determination of haemoglobin as an alternative to the cyanhaemiglobin method. I. description of the method
1984
A new method for the rapid and accurate measurement of haemoglobin has been developed as an alternative to the conventional cyanhaemiglobin method. This method is based on the conversion of all haeme, haemoglobin, and haemiglobin species into a stable end product by an alkaline solution of a non-ionic detergent ('AHD reagent'). The reaction product, designated as alkaline haematin D-575, is extremely stable and shows a characteristic absorption peak at 575 nm. As compared to the cyanhaemiglobin method, the determination of haemoglobin by alkaline haematin D-575 offers several advantages such as (1) extreme stability of the AHD reagent and the conversion product, (2) decreased conversion tim…
Identification of off-flavor compounds in high-density polyethylene (HDPE) with different amounts of abscents
1998
The use of synthetic pipes for drinking water distribution has increased. High desnity polyethylene (HPDE) is preferred because of its favorable mechanical properties, ease of handling during manufacturing, and low permeability to external contaminants. Off-flavor drinking water is a problem with plastic pipes. The compounds causing off-flavors are mainly carbonyl compounds. A combined zeolite called Abscents is used to eliminate odors and to remove odor-causing compounds. In this study, four different amounts of Abscents were added to raw HDPE pellets, and the influence on the off-flavor properties were analyzed. When the maximum amount of Abscents was added, almost all the carbonyl compou…
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
2010
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…