scholarly journals Crystallization Behavior and Strength of Natural Rubber. Role of Fatty Acids.

1999 ◽  
Vol 72 (12) ◽  
pp. 683-689
Author(s):  
SEIICHI KAWAHARA
Keyword(s):  
Fatty Acids ◽  
Natural Rubber ◽  
Crystallization Behavior

Thermal Properties and Crystallization Behavior of Highly Deproteinized Natural Rubber

1999 ◽  
Vol 72 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Seiichi Kawahara ◽  
Takashi Kakubo ◽  
Michio Suzuki ◽  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Thermal Expansion ◽  
Natural Rubber ◽  
Sodium Methoxide ◽  
Proteolytic Enzyme ◽  
Crystallization Behavior ◽  
Equilibrium Melting Temperature ◽  
Low Temperature Crystallization ◽  
Deproteinized Natural Rubber ◽  
Temperature Crystallization

Abstract Natural rubber was deproteinized with a proteolytic enzyme and surfactant to reduce nitrogen content less than 0.02%. The deproteinized rubber was further purified by acetone-extraction followed by transesterification with sodium methoxide. The density of rubber decreased and the thermal expansion coefficient increased by deproteinization and transesterification. The glass transition temperature, Tg, was slightly reduced after deproteinization and transesterification. These were explained in relation to the decrease in gel content of the rubber. The equilibrium melting temperature, Tm0, was practically unchanged by these treatments. The low-temperature crystallization between −30 and −10 °C was significantly influenced by free fatty acids present as a mixture and fatty acid groups linked to the rubber chain. The crystallization behavior was independent of Tg and Tm0 values.

Structural Characterization of Natural Polyisoprenes: Solve the Mystery of Natural Rubber Based on Structural Study

2001 ◽  
Vol 74 (3) ◽  
pp. 355-375 ◽  
Author(s):  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Natural Rubber ◽  
Structural Characterization ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Terminal Group ◽  
Radical Scavenger ◽  
Branch Points

Abstract Structural characterization of naturally occurring polyisoprenes was carried out to solve the mystery of natural rubber (NR), such as the biosynthesis mechanism of rubber formation, the origin of outstanding properties of NR and the role of rubber in rubber trees. The NMR analysis, based on terpenes and polyprenols as models, disclosed the structure of both terminal groups of rubber chain. Structural evidence indicated that the biosynthesis of rubbers from Lactarius mushroom and leaves of high plants starts from trans, trans-farnesyl diphosphate or trans, trans, trans-geranylgeranyl diphosphate and terminates by dephosphorylation to form a hydroxyl terminal group. The biosynthesis of NR was presumed to start from unidentified initiating species containing two trans-isoprene units and peptide group and to terminate forming a phospholipid terminal group. The initiating group of NR associated with proteins formed branch points, which can be decomposed by enzymatic deproteinization. The branch points formed by phospholipid group were decomposed by transesterification with sodium methoxide. Rapid crystallization of NR was explained by the presence of mixed fatty acids synergistically with linked fatty acids, which were included in phospholipid. Saturated fatty acids linked to rubber chain induced crystallization, while mixed unsaturated fatty acids acted as plasticizer and accelerated the crystallization rate. This was confirmed by the preparation of model cis-polyisoprene grafted with stearic acid. The green strength of NR decreased to the same level as synthetic cis-polyisoprene after transesterification, indicating the effect of branching formed by the phospholipid terminal group and fatty acids in NR. The role of NR in Hevea trees was analyzed using NR from Hevea trees never tapped before. The formation of hard gel and oxidative degradation during the storage of NR in Hevea trees suggested that NR acted as a radical scavenger to remove hydroperoxide.

Characterization of fatty acids linked to natural rubber—role of linked fatty acids on crystallization of the rubber

Polymer ◽  
2000 ◽  
Vol 41 (20) ◽  
pp. 7483-7488 ◽  
Author(s):  
S Kawahara ◽  
T Kakubo ◽  
J.T Sakdapipanich ◽  
Y Isono ◽  
Y Tanaka
Keyword(s):  
Fatty Acids ◽  
Natural Rubber

Alcohol intake impairs glucose counterregulation during acute insulin-induced hypoglycemia in IDDM patients. Evidence for a critical role of free fatty acids

Diabetes ◽  
1993 ◽  
Vol 42 (11) ◽  
pp. 1626-1634 ◽  
Author(s):  
A. Avogaro ◽  
P. Beltramello ◽  
L. Gnudi ◽  
A. Maran ◽  
A. Valerio ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Alcohol Intake ◽  
Critical Role

scholarly journals FSMP-15. EVALUATING THE ROLE OF LONG-CHAIN FATTY ACID METABOLISM IN PROMOTING GLIOBLASTOMA GROWTH

2021 ◽  
Vol 3 (Supplement_1) ◽  
pp. i19-i19
Author(s):  
Divya Ravi ◽  
Carmen del Genio ◽  
Haider Ghiasuddin ◽  
Arti Gaur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Survival Rate ◽  
Tumor Progression ◽  
Acid Synthesis ◽  
Normal Brain ◽  
Acid Uptake ◽  
Exogenous Fatty Acid ◽  
Long Chain

Abstract Glioblastomas (GBM) or Stage IV gliomas, are the most aggressive of primary brain tumors and are associated with high mortality and morbidity. Patients diagnosed with this lethal cancer have a dismal survival rate of 14 months and a 5-year survival rate of 5.6% despite a multimodal therapeutic approach, including surgery, radiation therapy, and chemotherapy. Aberrant lipid metabolism, particularly abnormally active de novo fatty acid synthesis, is recognized to have a key role in tumor progression and chemoresistance in cancers. Previous studies have reported a high expression of fatty acid synthase (FASN) in patient tumors, leading to multiple investigations of FASN inhibition as a treatment strategy. However, none of these have developed as efficacious therapies. Furthermore, when we profiled FASN expression using The Cancer Genome Atlas (TCGA) we determined that high FASN expression in GBM patients did not confer a worse prognosis (HR: 1.06; p-value: 0.51) and was not overexpressed in GBM tumors compared to normal brain. Therefore, we need to reexamine the role of exogenous fatty acid uptake over de novofatty acid synthesis as a potential mechanism for tumor progression. Our study aims to measure and compare fatty acid oxidation (FAO) of endogenous and exogenous fatty acids between GBM patients and healthy controls. Using TCGA, we have identified the overexpression of multiple enzymes involved in mediating the transfer and activation of long-chain fatty acids (LCFA) in GBM tumors compared to normal brain tissue. We are currently conducting metabolic flux studies to (1) assess the biokinetics of LCFA degradation and (2) establish exogenous versus endogenous LCFA preferences between patient-derived primary GBM cells and healthy glial and immune cells during steady state and glucose-deprivation.

scholarly journals Evaluation of Chemical Variability of Cured Vanilla Beans (Vanilla tahitensis and Vanilla planifolia)

2009 ◽  
Vol 4 (10) ◽  
pp. 1934578X0900401 ◽  
Author(s):  
Christel Brunschwig ◽  
François Xavier Collard ◽  
Jean-Pierre Bianchini ◽  
Phila Raharivelomanana
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Dry Matter ◽  
Monounsaturated Fatty Acids ◽  
Vanilla Planifolia ◽  
Chemical Variability ◽  
Total Fatty Acids ◽  
Curing Method ◽  
Fatty Acid Compositions

In order to establish a chemical fingerprint of vanilla diversity, thirty samples of V. planifolia J. W. Moore and V. tahitensis G. Jackson cured beans from seven producing countries were examined for their aroma and fatty acid contents. Both fatty acid and aroma compositions were found to vary between vanilla species and origins. Vanillin was found in higher amounts in V. planifolia (1.7-3.6% of dry matter) than in V. tahitensis (1.0-2.0%), and anisyl compounds were found in lower amounts in V. planifolia (0.05%) than in V. tahitensis (1.4%-2.1%). Ten common and long chain monounsaturated fatty acids (LCFA) were identified and were found to be characteristic of the vanilla origin. LCFA derived from secondary metabolites have discriminating compositions as they reach 5.9% and 15.8% of total fatty acids, respectively in V. tahitensis and V. planifolia. This study highlights the role of the curing method as vanilla cured beans of two different species cultivated in the same country were found to have quite similar fatty acid compositions.

scholarly journals Biocomposites of Epoxidized Natural Rubber/Poly(lactic acid) Modified with Natural Fillers (Part I)

2021 ◽  
Vol 22 (6) ◽  
pp. 3150
Author(s):  
Anna Masek ◽  
Stefan Cichosz ◽  
Małgorzata Piotrowska
Keyword(s):  
Tensile Strength ◽  
Lactic Acid ◽  
Natural Rubber ◽  
Epoxidized Natural Rubber ◽  
Poly Lactic Acid ◽  
Uv Aging ◽  
High Elasticity ◽  
Natural Fillers ◽  
Natural Additives

The study aimed to prepare sustainable and degradable elastic blends of epoxidized natural rubber (ENR) with poly(lactic acid) (PLA) that were reinforced with flax fiber (FF) and montmorillonite (MMT), simultaneously filling the gap in the literature regarding the PLA-containing polymer blends filled with natural additives. The performed study reveals that FF incorporation into ENR/PLA blend may cause a significant improvement in tensile strength from (10 ± 1) MPa for the reference material to (19 ± 2) MPa for the fibers-filled blend. Additionally, it was found that MMT employment in the role of the filler might contribute to ENR/PLA plasticization and considerably promote the blend elongation up to 600%. This proves the successful creation of the unique and eco-friendly PLA-containing polymer blend exhibiting high elasticity. Moreover, thanks to the performed accelerated thermo-oxidative and ultraviolet (UV) aging, it was established that MMT incorporation may delay the degradation of ENR/PLA blends under the abovementioned conditions. Additionally, mold tests revealed that plant-derived fiber addition might highly enhance the ENR/PLA blend’s biodeterioration potential enabling faster and more efficient growth of microorganisms. Therefore, materials presented in this research may become competitive and eco-friendly alternatives to commonly utilized petro-based polymeric products.

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