146 research outputs found

    Проект системы оборотного водоснабжения для охлаждения гальванических ванн

    Get PDF
    Объект разработки: Кожухотрубчатый теплообменник. Цель работы: Рассчитать теплообменник для охлаждения оборотной воды. В ходе выполнения работы: Выполнены все необходимые расчеты для конструирования аппарата. Определены размеры и основные механические характеристики. Основные конструктивные, технологические и технико-эксплуатационные характеристики: Диаметр аппарата 159 мм, длина теплообменных труб 3 м, диаметр труб 25х2 мм, рабочее давление трубного пространства 0,2Development object: Shell and tube heat exchanger. Purpose of work: Calculate a heat exchanger for cooling the circulating water. In the course of the work: All the necessary calculations for the design of the apparatus have been completed. The dimensions and main mechanical characteristics are determined. The main design, technological and technical and operational characteristics: The diameter of the apparatus is 159 mm, the length of the heat exchange tubes is 3 m, the diameter of the tube

    The genome and transcriptome of Trichormus sp NMC-1: insights into adaptation to extreme environments on the Qinghai-Tibet Plateau

    Get PDF
    The Qinghai-Tibet Plateau (QTP) has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. In this study, we generated a draft genome sequence of cyanobacteria Trichormus sp. NMC-1 in the QTP and performed whole transcriptome sequencing under low temperature to investigate the genetic mechanism by which T. sp. NMC-1 adapted to the specific environment. Its genome sequence was 5.9 Mb with a G+C content of 39.2% and encompassed a total of 5362 CDS. A phylogenomic tree indicated that this strain belongs to the Trichormus and Anabaena cluster. Genome comparison between T. sp. NMC-1 and six relatives showed that functionally unknown genes occupied a much higher proportion (28.12%) of the T. sp. NMC-1 genome. In addition, functions of specific, significant positively selected, expanded orthogroups, and differentially expressed genes involved in signal transduction, cell wall/membrane biogenesis, secondary metabolite biosynthesis, and energy production and conversion were analyzed to elucidate specific adaptation traits. Further analyses showed that the CheY-like genes, extracellular polysaccharide and mycosporine-like amino acids might play major roles in adaptation to harsh environments. Our findings indicate that sophisticated genetic mechanisms are involved in cyanobacterial adaptation to the extreme environment of the QTP

    Application of an universal DNA microarray to cyanobacterial diversity assessment

    Full text link
    peer reviewedOur technological goal was to test the new technology of DNA microarrays in the field of biodiversity assessments. The efficiency of DNA microarrays; was compared against the "classical" methods for measuring and monitoring the biodiversity. We use cyanobacteria from freshwater lakes as model organisms belonging to a well defined phylum of much ecological relevance. The combination of the information about cyanobacterial biodiversity together with the data describing the water quality of the lakes may reveal useful information to design management actions to control the unwanted mass developments of cyanobacteria. Such blooms prevent the use of water for drinking and for recreation and can be toxic to animals and humans. The possibility to automate the microarray technology in water quality monitoring will be an interesting alternative to time-consuming microscopic enumerations.MIDI-CHI

    Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives.

    Get PDF
    In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in ecosystems with low species diversity, functional and phylogenetic approaches may not provide additional insight over a species-based approach

    Relationship between Reproductive Allocation and Relative Abundance among 32 Species of a Tibetan Alpine Meadow: Effects of Fertilization and Grazing

    Get PDF
    Background: Understanding the relationship between species traits and species abundance is an important goal in ecology and biodiversity science. Although theoretical studies predict that traits related to performance (e.g. reproductive allocation) are most directly linked to species abundance within a community, empirical investigations have rarely been done. It also remains unclear how environmental factors such as grazing or fertilizer application affect the predicted relationship. Methodology: We conducted a 3-year field experiment in a Tibetan alpine meadow to assess the relationship between plant reproductive allocation (RA) and species relative abundance (SRA) on control, grazed and fertilized plots. Overall, the studied plant community contained 32 common species. Principal Findings: At the treatment level, (i) RA was negatively correlated with SRA on control plots and during the first year on fertilized plots. (ii) No negative RA–SRA correlations were observed on grazed plots and during the second and third year on fertilized plots. (iii) Seed size was positively correlated with SRA on control plots. At the plot level, the correlation between SRA and RA were not affected by treatment, year or species composition. Conclusions/Significance: Our study shows that the performance-related trait RA can negatively affect SRA within communities, which is possibly due to the tradeoffs between clonal growth (for space occupancy) and sexual reproduction. We propose that if different species occupy different positions along these tradeoffs it will contribute to biodiversity maintenance in local communities or even at lager scale
    corecore