The mechanical and heat properties of fully biodegradable elastomer PHA and PLA composites were studied. The effects of types and contents of coupling agents, mesh and contents of Talc on mechanical properties, MFR of PHA/PLA composites were studied. We found that when PHA: PLA=70:30, the PHA/PLA composites are stiff, flexible and good heat resistant. With 1% ligand titanic acid ester coupling agent treat 20 parts of 3000 mesh Talc, we can get the best PHA/PLA/Talc ternary composites. The DSC results indicate that the PHA/PLA/Talc ternary composite has the rapid crystallization temperature between 50-75°C, the melt temperature is about 150°C.
Thermoplastic polyurethane (TPU) has been used to toughen Poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and increase its cold-resistance. The compatibility of P34HB/TPU blends was predicted by solubility parameter, then investigated by appearance and transparence, Dynamic Mechanical Analysis (DMA) and Scanning Electron Microscopy (SEM) analysis. The P34HB/TPU was found to be a partly compatible system. The appearance and transparence of P34HB/TPU blends were smooth and non-transparent. The DMA showed that the glass transition temperature of P34HB was decreased with the increase of TPU content. The SEM photos showed that the morphology of the P34HB/TPU blends were the sea island structure.
Binary blendscomposed of polyhrdroxyalkanoates (P34HB) and poly(lactic acid) (PLA) with various P34HB weight percentage were preparedby extrusion and compressing molding.Both the thermo-oxidative agingat 80°Cand the hydrothermal aging at 80°C with 80% humidity were performed for 300 h for the P34HB/PLA blends respectively.The mechanical properties of tensile strength and elongation-at-breakrevealed that P34HB/PLA blends possessedthe balanced mechanical properties between P34HB and PLA,theblends with higher ratio of P34HBshowed thedeteriorative mechanical behavior in the aging environment faster than thoseblends with lower ratio of P34HB.
BackgroundIARS2 (EC6.1.5) is a mitochondrial isoleucine-tRNA synthetase. Despite the fact that only fewer than 30 patients have been reported in the literature, mitochondrial disorders caused by pathogenic variants in the IARS2 gene (OMIM: 616007) have a very broad and variable clinical phenotype spectrum. We present a child who has sideroblastic anemia and hypoparathyroidism as a result of a previously unreported mutation in the IARS2 gene.Case presentationA 14-year-old girl who had been anemic for 12 years was diagnosed with pure red cell aplasia (hemoglobin 42 g/L, reference range 110–160) at the age of 2. Her anemia was resistant to high-dose intravenous gamma globulin and cyclosporine therapy and required monthly blood transfusions to maintain normal hemoglobin levels. She developed cataracts at the age of 6 and was cured by phacoemulsification. At the age of 8, she visited the endocrine department, because of mental and physical retardation accompanied by repeated convulsions, and the antiepileptic treatment was ineffective. She was diagnosed with hypoparathyroidism. To control the convulsions, she was given calcitriol orally as well as large doses of calcium supplements. Due to severe growth and development delays, delayed sexual development, and hypokinesia at the age of 13.5Y, the parents agreed to a whole-exon gene sequencing test. IARS2 gene compound heterozygous variants c.2450G > A (p.Arg817His) and c.2511del (p.Leu838Phefs*69) were discovered. The girl was then diagnosed with IARS2-related disease and given a cocktail therapy of coenzyme Q10, vitamin B2, L-Carnitine and vitamin E. Although the child's clinical symptoms improved, she still experienced intermittent claudication and hip joint pain. The vitamin B6 was discontinued after three months due to its ineffectiveness in treating anemia. Because the child's ferritin levels remained elevated, she was also prescribed long-term oral deferiprone therapy.ConclusionOur findings broaden the clinical and genetic spectrum of IARS2-associated disease, and case summaries help raise clinical awareness of IARS2-associated disease and reduce under- and misdiagnosis.
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