CRESTED SHEAR CONNECTORS APPLICATION TO COMBINE REINFORCED CONCRETE SLAB AND PLANK-NAILED STRUCTURE OF BRIDGE SPAN

Introduction. The construction of bridges using timber materials is experiencing a real boom throughout the world .The USA is considered to be a leader, where 80% of the bridges are made of timber or materials based on it. In Russia timber bridge construction has been stagnating for the last 50 years, although there is a need for these bridges. Timber structures could solve many problems with Russian roads, especially in remote areas. Timber structures are widely considered to be outdated, so they cannot meet current requirements of load capacity and durability, also they are vulnerable to atmospheric influences, etc. But foreign experience proves the contrary. The article is devoted to the implementation of new plank-nailed spans that meet current requirements of load capacity, reliability and durability.Materials and methods. The authors suggest and describe a new span structure. The span consists of planktimber- nailed-dowel blocks and a reinforced concrete slab generating a composite action. Some special crested shear connectors are suggested as combining elements. The top part works as flexible shear connectors in a reinforced concrete slab. The bottom part works as dowels with steel joints and timbers structures. The investigation of the stress-strain state of the structure has been completed within “compound beam” theory.Results. The application of the cast-in-place reinforced concrete slab allows to protect supporting timber structures against atmospheric influences, dirt, cracking from the sun rays, radiation and provides at least 50-year durability. The timber preservation provides a specified service life. The application of suggested connection with composite action between a reinforced concrete slab and supporting timber structures increases effectiveness of the composite timber concrete structure compared to steel and reinforced concrete structures. Trans-Baikal territory, Irkutsk and Arkhangelsk Regions, Khabarovsk Territory, the Republics of Sakha (Yakutia), Buriatia, Karelia are in the greatest need of the timber concrete composite spans, because they have a lot of forest resources and old timber bridges that are still in service

Chitosan Sponges for Efficient Accumulation and Controlled Release of C-Phycocyanin

The paper proposed a new porous material for wound healing based on chitosan and C-phycocyanin (C-PC). In this work, C-PC was extracted from the cyanobacteria Arthrospira platensis biomass and purified through ammonium sulfate precipitation. The obtained C-PC with a purity index (PI) of 3.36 ± 0.24 was loaded into a chitosan sponge from aqueous solutions of various concentrations (250, 500, and 1000 mg/L). According to the FTIR study, chitosan did not form new bonds with C-PC, but acted as a carrier. The encapsulation efficiency value exceeded 90%, and the maximum loading capacity was 172.67 ± 0.47 mg/g. The release of C-PC from the polymer matrix into the saline medium was estimated, and it was found 50% of C-PC was released in the first hour and the maximum concentration was reached in 5–7 h after the sponge immersion. The PI of the released C-PC was 3.79 and 4.43 depending on the concentration of the initial solution

Spectrum and Frequency of the GJB2 Gene Pathogenic Variants in a Large Cohort of Patients with Hearing Impairment Living in a Subarctic Region of Russia (the Sakha Republic).

Pathogenic variants in the GJB2 gene, encoding connexin 26, are known to be a major cause of hearing impairment (HI). More than 300 allelic variants have been identified in the GJB2 gene. Spectrum and allelic frequencies of the GJB2 gene vary significantly among different ethnic groups worldwide. Until now, the spectrum and frequency of the pathogenic variants in exon 1, exon 2 and the flanking intronic regions of the GJB2 gene have not been described thoroughly in the Sakha Republic (Yakutia), which is located in a subarctic region in Russia. The complete sequencing of the non-coding and coding regions of the GJB2 gene was performed in 393 patients with HI (Yakuts-296, Russians-51, mixed and other ethnicities-46) and in 187 normal hearing individuals of Yakut (n = 107) and Russian (n = 80) populations. In the total sample (n = 580), we revealed 12 allelic variants of the GJB2 gene, 8 of which were recessive pathogenic variants. Ten genotypes with biallelic recessive pathogenic variants in the GJB2 gene (in a homozygous or a compound heterozygous state) were found in 192 out of 393 patients (48.85%). We found that the most frequent GJB2 pathogenic variant in the Yakut patients was c.-23+1G>A (51.82%) and that the second most frequent was c.109G>A (2.37%), followed by c.35delG (1.64%). Pathogenic variants с.35delG (22.34%), c.-23+1G>A (5.31%), and c.313_326del14 (2.12%) were found to be the most frequent among the Russian patients. The carrier frequencies of the c.-23+1G>A and с.109G>A pathogenic variants in the Yakut control group were 10.20% and 2.80%, respectively. The carrier frequencies of с.35delG and c.101T>C were identical (2.5%) in the Russian control group. We found that the contribution of the GJB2 gene pathogenic variants in HI in the population of the Sakha Republic (48.85%) was the highest among all of the previously studied regions of Asia. We suggest that extensive accumulation of the c.-23+1G>A pathogenic variant in the indigenous Yakut population (92.20% of all mutant chromosomes in patients) and an extremely high (10.20%) carrier frequency in the control group may indicate a possible selective advantage for the c.-23+1G>A carriers living in subarctic climate

Prevalence of congenital HI caused by biallelic <i>GJB2</i> pathogenic variants in the Sakha Republic.

<p>Note: The territory of the Sakha Republic is shown in blue (bottom map). HI rates were calculated per 10,000 people, and appropriate data are presented only for the districts and cities of the Sakha Republic with population more than 10,000. Detailed data are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0156300#pone.0156300.s001" target="_blank">S1 Table</a>.</p