scholarly journals Thermoplastic polyester elastomers based on long-chain crystallizable aliphatic hard segments

2015 ◽  
Vol 6 (40) ◽  
pp. 7133-7137 ◽  
Author(s):  
Florian Stempfle ◽  
Brigitta Schemmer ◽  
Anna-Lena Oechsle ◽  
Stefan Mecking
Keyword(s):  
Dicarboxylic Acid ◽  
Plant Oil ◽  
Hard Segments ◽  
Long Chain

Thermoplastic polyester elastomers prepared from a plant-oil derived crystallizable long-chain aliphatic α,ω-dicarboxylic acid have been investigated.

scholarly journals Reduced Plasma Levels of Very-Long-Chain Dicarboxylic Acid 28:4 in Italian and Brazilian Colorectal Cancer Patient Cohorts

Metabolites ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 91 ◽  
Author(s):  
Paul Wood ◽  
Michelle Donohue ◽  
John Cebak ◽  
Taylor Beckmann ◽  
Márcia Messias ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Dicarboxylic Acid ◽  
Cancer Patients ◽  
Plasma Levels ◽  
High Resolution Mass Spectrometry ◽  
Sporadic Colorectal Cancer ◽  
Inherited Susceptibility ◽  
Potential Biomarker ◽  
Colorectal Cancer Patients ◽  
Long Chain

Background: There are currently no blood-based biomarkers for early diagnosis of colorectal cancer. Previous research has suggested that very-long-chain dicarboxylic acid (VLCDCA) 28:4 might be such a biomarker. Methods: Using high-resolution mass spectrometry, we analyzed VLCDCA 28:4 in the plasma of colorectal cancer patients in Italian [n = 62] and Brazilian [n = 52] cohorts. Additionally, we investigated individuals diagnosed with familial adenomatous polyposis (FAP; n = 27), one of the most important clinical forms of inherited susceptibility to colorectal cancer. Results: Decrements in plasma levels of VLCDCA 28:4 were monitored in colorectal cancer patients. These decreases were independent of the stage of tumor development and the individual’s age. However, no decrements in VLCDCA 28:4 were monitored in FAP patients. Conclusions: The plasma levels of VLCDCA 28:4 represent a potential biomarker of sporadic colorectal cancer. In addition, it is possible that resupply of this anti-inflammatory lipid may represent a new therapeutic strategy for CRC and inflammatory disorders.

Rheology of Thermoplastic Polyurethanes

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Rheological Behavior ◽  
Thermoplastic Polyurethane ◽  
Complete Characterization ◽  
Chain Extender ◽  
Reaction Sequence ◽  
Molecular Weights ◽  
Soft Segments ◽  
Hard Segments ◽  
A Chain ◽  
Long Chain

Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.

Secretion in long-chain dicarboxylic acid fermentation

2000 ◽  
Vol 22 (5) ◽  
pp. 391-396 ◽  
Author(s):  
R. Lin ◽  
Z. Cao ◽  
T. Zhu ◽  
Z. Zhang
Keyword(s):  
Dicarboxylic Acid ◽  
Acid Fermentation ◽  
Long Chain

Intermediary metabolism of Acinetobacter grown on dialkyl ethers

1989 ◽  
Vol 35 (11) ◽  
pp. 1031-1036 ◽  
Author(s):  
Malcolm C. Modrzakowski ◽  
William R. Finnerty
Keyword(s):  
Fatty Acids ◽  
Dicarboxylic Acid ◽  
Chain Length ◽  
Dicarboxylic Acids ◽  
Acid Oxidation ◽  
Methyl Group ◽  
Ether Oxygen ◽  
Dialkyl Ethers ◽  
Long Chain ◽  
Methyl Group Oxidation

The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.

Plant Oil-Based Long-Chain C26Monomers and Their Polymers

2012 ◽  
Vol 213 (21) ◽  
pp. 2220-2227 ◽  
Author(s):  
Carla Vilela ◽  
Armando J. D. Silvestre ◽  
Michael A. R. Meier
Keyword(s):  
Plant Oil ◽  
Long Chain

scholarly journals Synthesis of copolyesters with bio-based lauric diacid: structure and physico-mechanical studies

RSC Advances ◽  
2017 ◽  
Vol 7 (87) ◽  
pp. 55418-55426 ◽  
Author(s):  
Meiling Chen ◽  
Nesren A. H. Saada ◽  
Fei Liu ◽  
Haining Na ◽  
Jin Zhu
Keyword(s):  
Mechanical Properties ◽  
Dicarboxylic Acid ◽  
Biodegradable Materials ◽  
Long Chain ◽  
Mechanical Studies

Copolyesters developed from bio-based long-chain dicarboxylic acid show promising mechanical properties that are helpful for their application as biodegradable materials.

Synthesis and blood compatibilities of novel segmented polyurethanes containing phosphatidylcholine analogous moieties in the main chains and long-chain alkyl groups in the side chains

1999 ◽  
Vol 14 (9) ◽  
pp. 3789-3798 ◽  
Author(s):  
Arata Korematsu ◽  
Yu-Jun Li ◽  
Takayuki Murakami ◽  
Tadao Nakaya
Keyword(s):  
Platelet Adhesion ◽  
Platelet Rich Plasma ◽  
Side Chains ◽  
Alkyl Groups ◽  
Low Degree ◽  
Soft Segments ◽  
Hard Segments ◽  
Segmented Polyurethanes ◽  
Methylenediphenyl Diisocyanate ◽  
Long Chain

New segmented polyurethanes containing phospholipid moieties in the main chains and long-chain alkyl groups in the side chains were synthesized. The soft segments used in this study were poly(butadiene), poly(isoprene), hydrogenated poly(isoprene), and poly(1,6-hexyl-1,2-ethylcarbonate) diol. The hard segments of these polyurethanes were 4,4′-methylenediphenyl diisocyanate, bis[2-(2-hydroxyethyldimethylammonio)ethyl]2-cetyl- 1,3-propanediphosphate, and 1,4-butanediol. The blood compatibilities of the new polymers were evaluated by platelet-rich plasma contact studies and viewed by scanning electron microscopy using medical grade BioSpan® and nonphospholipid polyurethane as references. These new materials have good surfaces in terms of platelet adhesion, and the morphology of adhered platelets undergoes a relatively low degree of variation.

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