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Chemical Composition Analysis (chemical + composition_analysis)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Wood-thermoplastic composites manufactured using beetle-killed spruce from Alaska

POLYMER ENGINEERING & SCIENCE, Issue 1 2009
Vikram Yadama
The primary objectives of the study were to characterize the critical properties of wood flour produced using highly deteriorated beetle-killed spruce for wood-plastic composite (WPC) production and evaluate important mechanical and physical properties of WPC extruded using an industry standard formulation. Chemical composition analysis indicated no significant differences in wood constituents between highly deteriorated and sound wood. Preliminary investigation with Fourier transform infrared spectroscopy (FTIR), however, indicated partial degradation or depolymerization of carbohydrate components in highly deteriorated wood compared to sound wood from green trees; effects of these changes could be seen in cell collapse and poor interaction between thermoplastic matrix and deteriorated wood fiber. Physical and mechanical properties of extruded WPCs manufactured from highly deteriorated material were comparable to WPC properties produced using pine wood flour that served as a control material. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers [source]

The Structure of a Novel Neutral Lipid,A from the Lipopolysaccharide of Bradyrhizobium elkanii Containing Three Mannose Units in the Backbone

CHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2010
Iwona Komaniecka Dr.
Abstract The chemical structure of the lipid,A of the lipopolysaccharide (LPS) from Bradyrhizobium elkanii USDA 76 (a member of the group of slow-growing rhizobia) has been established. It differed considerably from lipids,A of other Gram-negative bacteria, in that it completely lacks negatively charged groups (phosphate or uronic acid residues); the glucosamine (GlcpN) disaccharide backbone is replaced by one consisting of 2,3-dideoxy-2,3-diamino- D -glucopyranose (GlcpN3N) and it contains two long-chain fatty acids, which is unusual among rhizobia. The GlcpN3N disaccharide was further substituted by three D -mannopyranose (D -Manp) residues, together forming a pentasaccharide. To establish the structural details of this molecule, 1D and 2D,NMR spectroscopy, chemical composition analyses and high-resolution mass spectrometry methods (electrospray ionisation Fourier-transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) and tandem mass spectrometry (MS/MS)) were applied. By using 1D and 2D,NMR spectroscopy experiments, it was confirmed that one D -Manp was linked to C-1 of the reducing GlcpN3N and an ,-(1,6)-linked D -Manp disaccharide was located at C-4, of the non-reducing GlcpN3N (,-linkage). Fatty acid analysis identified 12:0(3-OH) and 14:0(3-OH), which were amide-linked to GlcpN3N. Other lipid,A constituents were long (,-1)-hydroxylated fatty acids with 26,33 carbon atoms, as well as their oxo forms (28:0(27-oxo) and 30:0(29-oxo)). The 28:0(27-OH) was the most abundant acyl residue. As confirmed by high-resolution mass spectrometry techniques, these long-chain fatty acids created two acyloxyacyl residues with the 3-hydroxy fatty acids. Thus, lipid,A from B. elkanii comprised six acyl residues. It was also shown that one of the acyloxyacyl residues could be further acylated by 3-hydroxybutyric acid (linked to the (,-1)-hydroxy group). [source]

DPPH free-radical scavenging ability, total phenolic content, and chemical composition analysis of forty-five kinds of essential oils

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2009
H.-F. Wang
J. Cosmet. Sci., 59, 509,522 (November/December 2008) Synopsis Forty-five kinds of commonly used essential oils were employed to investigate the DPPH (1,1-diphenyl2-picrylhydrazyl) radical scavenging ability and total phenolic content of major chemical compositions. The free-radical scavenging ability and total phenolic content of cinnamon leaf and clove bud essential oils are the best among these essential oils. One-half milliliter of cinnamon leaf and clove bud essential oils (10 mg mL EtOH) are shown to be 96.74% and 96.12% of the DPPH (2.5ml, 1.52 × 10 -4 M) free-radical scavenging ability, respectively. Their EC50 (effective concentrations) are 53 and 36 (,g mL -1). One milligram per milliliter of cinnamon leaf, clove bud, and thyme red essential oils were shown to be 420, 480, and 270 (mg g -1 of GAE) of total phenolic content, respectively. Eugenol in cinnamon leaf and clove bud essential oils (82.87% and 82.32%, respectively) were analyzed by GC-MS. It is clear that the amounts of the phenol compounds in essential oils and the DPPH free-radical scavenging ability are in direct proportion. [source]

Acetaldehyde plasma polymer-coated PET fibers for endothelial cell patterning: Chemical, topographical, and biological analysis

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010
Afra Hadjizadeh
Abstract The objective of this study was to produce fibrous biomaterials with cell adhesive and cell repulsive capabilities for biomedical applications. To this aim, the surface of 100-,m diameter polyethylene terephthalate fibers were functionalized with acetaldehyde plasma polymer deposition followed by carboxymethyl dextran grafting onto the aldehyde-coated surfaces via a polyethyleneimine interlayer. The performance of the surface modification steps were confirmed by surface chemical composition analysis using X-ray photoelectron spectroscopy, surface topography analysis by atomic force microscopy, and scanning electron microscopy. The acetaldehyde plasma polymer-coated and polyethyleneimine-grafted substrates promoted human umbilical vein endothelial cells attachment, spreading and actin filaments/focal adhesions formation. In contrast, carboxymethyl dextran-grafted substrates resisted cell adhesion. These observations demonstrate that the current surface-modified polymer fibers can be used in tissue engineering applications, such as cell patterning substrates or vascular prosthesis development. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. [source]