Nucleotide differences in the mbf1 gene of the lichenized fungus Umbilicaria decussata collected in polar and non-polar regions

Multiprotein bridging factor 1 (MBF1) is a transcriptional co-activator related to stress tolerance in various organisms. We investigated the nucleotide differences in the mbf1 gene in the lichen-forming fungus Umbilicaria decussata collected from polar (i.e., Antarctica and the Arctic) and non-polar (i.e., Armenia) regions. The 552-bp Udmbf1 genes isolated from eight samples contained numerous sequence variations, including single nucleotide polymorphisms as well as insertions and deletions. The frequency of nucleotide changes was higher in the intron than in the coding sequence. The nucleotide polymorphism levels (π=0.01792, θ=0.01792) and haplotype diversity (Hd=1) in the Udmbf1 gene from Antarctic samples were relatively high. Additionally, of the 19 detected nucleotide sequence variation sites, 15 were observed only in Antarctic samples. The resulting amino acid changes occurred in the N-terminal, whose function remains unknown. Although these DNA polymorphisms and amino acid changes have been verified in Antarctic samples of U. decussata, there is still little evidence indicating that different environmental conditions affected the functional evolution of Udmbf1. Additional studies involving more U. decussata samples from representative ecotypes will be necessary to uncover the relationships among DNA polymorphisms, functional gene evolution, and lichen habitats

Natural convection heat transfer of a straight-fin heat sink

The influence of mounting angle on heat dissipation performance of a heat sink under natural convection condition is investigated in this paper by numerical simulation and experimental test. It is found that the heat sink achieves the highest cooling power when its mounting angle is 90°, while it reaches the lowest when the mounting angle is 15°, which is 6.88% lower than that of 90°. A heat transfer stagnation zone is the main factor that affects the cooling power of the heat sink, and its location and area vary with the mounting angle. It is identified that cutting the heat transfer stagnation zone is an effective way to improve the heat sink performance

Measurements in degassing processes of CO2_{{2}} solution with particular reference to CO2_{{2}}-driven limnic eruptions

CO2-driven limnic eruptions are lethal phenomena that occur in lakes with aqueous CO2 solutions that become supersaturated. The exsolution of massive CO2 dissolved in the water can happen in a very short time, possibly leading to a natural disaster as happened in the Lake Nyos (Cameroon, Africa) in 1986. More than 1700 people died. In recent years, with the utilization of the technology of CO2 sequestration in brines in geological reservoirs, there are possibilities of the CO2-brine leakage. The brine may stay in the near surface water leading to the potential of an eruption. In this experimental study, measurements have been carried out to investigate the degassing processes of CO2 solutions under different depressurizing conditions. Based on the experimental data and using the ImagePro Plus® to process the recorded images, two correlations have been obtained: (1) the relationship between the supersaturation (${\Delta }P$) required for degassing and the initial pressure; (2) the relationship between the time delay (${\Delta }t$) corresponding to bubble formation and the initial pressure. Variations of key quantities (void fraction, number of bubbles, and average diameter of bubbles) over time have been analyzed. In addition, the void fractions measured in two different depressurizing ways have been compared. The experimental data and correlations obtained in this study are useful in establishing transient fluid dynamic models for simulating CO2-driven eruptions

Measurements in degassing processes of CO2_{{2}} solution with particular reference to CO2_{{2}}-driven limnic eruptions

CO2-driven limnic eruptions are lethal phenomena that occur in lakes with aqueous CO2 solutions that become supersaturated. The exsolution of massive CO2 dissolved in the water can happen in a very short time, possibly leading to a natural disaster as happened in the Lake Nyos (Cameroon, Africa) in 1986. More than 1700 people died. In recent years, with the utilization of the technology of CO2 sequestration in brines in geological reservoirs, there are possibilities of the CO2-brine leakage. The brine may stay in the near surface water leading to the potential of an eruption. In this experimental study, measurements have been carried out to investigate the degassing processes of CO2 solutions under different depressurizing conditions. Based on the experimental data and using the ImagePro Plus® to process the recorded images, two correlations have been obtained: (1) the relationship between the supersaturation (${\Delta }P$) required for degassing and the initial pressure; (2) the relationship between the time delay (${\Delta }t$) corresponding to bubble formation and the initial pressure. Variations of key quantities (void fraction, number of bubbles, and average diameter of bubbles) over time have been analyzed. In addition, the void fractions measured in two different depressurizing ways have been compared. The experimental data and correlations obtained in this study are useful in establishing transient fluid dynamic models for simulating CO2-driven eruptions

Spatio-temporal variations and influencing factors of polycyclic aromatic hydrocarbons in atmospheric bulk deposition along a plain-mountain transect in western China

Ten atmospheric bulk deposition (the sum of wet and dry deposition) samplers for polycyclic aromatic hydrocarbons (PAHs) were deployed at a plain-mountain transect (namely PMT transect, from Daying to Qingping) in Chengdu Plain, West China from June 2007 to June 2008 in four consecutive seasons (about every three months). The bulk deposition fluxes of ∑15-PAHs ranged from 169.19 μg m−2 yr−1 to 978.58 μg m−2 yr−1 with geometric mean of 354.22 μg m−2 yr−1. The most prevalent PAHs were 4-ring (39.65%) and 3-ring (35.56%) PAHs. The flux values were comparable to those in rural areas. Higher fluxes of total PAHs were observed in the middle of PMT transect (SL, YX and JY, which were more urbanized than other sites). The seasonal deposition fluxes in the sampling profile indicated seasonality of the contaminant source was an important factor in controlling deposition fluxes. PAHs bulk deposition was negatively correlated with meteorological parameters (temperature, wind speed, humidity, and precipitation). No significant correlations between soil concentrations and atmospheric deposition were found along this transect. PAHs in soil samples had combined sources of coal, wood and petroleum combustion, while a simple source of coal, wood and grass combustion for bulk deposition. There were significant positive correlation relationship (p < 0.05) between annual atmospheric bulk deposition and local PAHs emission, with biomass burning as the major contribution to the total emission of PAHs. This transect acts as an important PAHs source rather than being a sink according to the ratio of deposition/emission. Mountain cold trap effect existed in this transect where the altitude was higher than 1000 m. Long-range transport had an impact on the bulk deposition in summer. And this transect was a source to Tibetan only in summer. The forward trajectory analysis showed most air masses did not undergo long-range transport due to the blocking effect of surrounding mountains. Only a few air masses (<10%) arrived at the eastern and northern region of China or farther regions via long-range transport

Experimental study of an organic Rankine cycle system with radial inflow turbine and R123

A new micro radial inflow turbine is developed fora mini organic Rankine cycle (ORC) system in this study. With R123 as the working fluid, the turbine operational characteristics and performance are investigated by experiments. Based on the experimental data, the maximum rotational speed of the radial inflow turbine reaches53564r/min, and the maximum output power of the turbine is3.386kW and the maximum electric power reaches1.884kW. When the turbine rotational speed is34586r/min, the system isentropic and electromechanical efficiencies achieve the maximum values of 83.6% and65.3% respectively. Both the turbine isentropic and thermal efficiencies increase with the heat source temperature