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Showing 2 results for Natural Rubber
M. Salehi, A. Musavi ,
Volume 19, Issue 1 (1-2019)
Abstract
Considering the hazards of noise pollutions and their increasing trend, nowadays, sound insulations are of the utmost importance. Some available insulating blankets in the market are made of foam and absorb moisture, while the other types of common insulations are fragile and vulnerable. Most of the insulations cannot be used in available construction materials and decrease the beauty of atmosphere. The insulations, which do not have the mentioned problems, are expensive. The current study aims at introducing an insulation, which does not have these problems and resists moisture at a reasonable price. This insulation is made of natural rubber and polyester fibers. It has a considerable flexibility and can be combined with other construction materials. In this experimental study, different samples of one-layer and two-layer natural rubbers with 2.2 mm thickness for each layer were produced with and without fibers in compression molding method. They were tested in various frequencies and compared with the results of common XPS sound insulation. Each of the samples had a good performance in a specific frequency. All samples exhibited an acceptable behavior compared with their peers in the market. Each of the samples performed better at a certain frequency. In conclusion, the best performance is related to the two-layer rubber sample with fibers and the present insulation in the market is in the second rank.
Volume 24, Issue 6 (11-2022)
Abstract
MicroRNAs are endogenous noncoding RNA that play vital roles in all plant cellular metabolic processes by mediating target gene expression. To date, miRNAs in Taraxacum spp., which is an important industrial plant, have remained largely unknown. In the present study, 970 miRNAs from 399 families were identified in Taraxacum spp by conducting computational approaches. The most frequent miRNAs in Taraxacum spp was miR5021. According to the KEGG results, miR5021, miR838, and miR1533 are related to the terpene biosynthesis pathway, while miR5015b, and miR1436 are involved in the starch and sucrose biosynthesis pathways. Quantitative real-time PCR assay was performed to validate the expression levels of five predicted miRNAs and 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase (HMGCR) and invertase as the target genes. Results indicated that the highest relative expression of miR1533 and miR1436 occurred in the flower, while the highest transcripts levels of miR5015b were observed in the stem. In addition, the higher relative expression level of the miR5021 and miR838 was consistent with the lower expression level of the HMGCR gene in all tissue, suggesting that miR5021 and miR838 are involved in regulating HMGCR gene expression. Since mevalonate pathway is the main source of isopentenyl pyrophosphate, which is used in the synthesis of rubber, miR5021 and miR838 play an important role in the production of rubber by regulating the expression of HMGCR enzyme. These findings will accelerate future perspective studies on the regulatory mechanisms of miRNAs in Taraxacum kok-saghyz.
