Fire Resistant Study for Long Span Beams Made of FR 490 Steels

Building could be severely influenced by fire and it can be demolished so that the major structural elements such as columns and beams required to be coated by fire protection materials according to each condition. Especially, a steel framed building regarded as a weaken structures when the building is engulfed with a severe fire condition. Therefore, the fire resistant steel (FR 490) has been developed to improve the structural properties of an ordinary structural steels at high temperature. Generally, the fire resistance of structural beam built with a structural steel can be measured by horizontal furnace using a standard testing method by each nation’s standard. However, the real length of the beam showed the tendency longer than that of the horizontal furnace. Therefore, it is considered more important to know the real fire resistant performance of structural beams. In this paper, to evaluate the fire resistant performance of long span beams made of the FR 490, the fire engineering method is done using not only materials properties at high temperatures but a heat transfer, a stress theory. The results showed that as the length of beams are longer, the maximum load bearing capacities at high temperatures are lower and the deflections are increased

Fire Resistance on Bearing Wall Using Steel & Gypsum

The conventional loadbearing wall systems generally used in Korea are composed of concrete and brick. Which materials have many defaults like long-term construction period and cost increase. Recently in us, a rapid increase in the usage of cold-formed steel section in housing and commercial building construction can widely be seen. The loadbearing wall assembly composed of light gauge-steel and gypsum board can preferably be applied to residential and commercial building of 5 stories or below. In order that light-gauge steel framing can be prevalently introduced in our domestic housing market, the wall assembly must have sufficient fire-resistant performance. Fire-resistant tests were conducted for the load bearing wall specimens of 7.2m² in size and fire tests were carried out on load-bearing wall systems by method of loading condition and unloading condition in full size of specimens in order to certify the fire-resistance properties. Through test results, the temperature slopes of each material such as steel, insulation and gypsum board were obtained, along with the vertical and horizontal deflection of specimens

Decadal changes in the leading patterns of sea level pressure in the Arctic and their impacts on the sea ice variability in boreal summer

Besides its negative trend, the interannual and the interdecadal changes in the Arctic sea ice have also been pronounced in recent decades. The three leading modes in the sea level pressure (SLP) variability in the Arctic (70???90??????N) ??? the Arctic Oscillation (AO), the Arctic Dipole (AD), and the third mode (A3) ??? are analyzed to understand the linkage between sea ice variability and large-scale atmospheric circulation in boreal summer (June???August). This study also compares the decadal changes of the modes between the early (1982???1997) and the recent (1998???2017) periods and their influences on the Arctic sea ice extent (SIE). Only the AD mode shows a significant correlation increase with SIE in summer (JJA) from ???0.05 in the early period to 0.57 in the recent period. The AO and the A3 modes show a less significant relationship with SIE for the two periods. The AD is characterized by a dipole pattern of SLP, which modulates the strength of meridional surface winds and the Transpolar Drift Stream (TDS). The major circulation change in the late 1990s is that the direction of the wind has been changed more meridionally over the exit region of the Fram Strait, which causes sea ice drift and discharge through that region. In addition, the response of surface albedo and the net surface heat flux becomes larger and much clearer, suggesting a positive sea-ice???albedo feedback in the sea ice variability associated with the AD. The analysis also reveals that the zonal shift of the centers of SLP anomalies and associated circulation change affects a significant reduction in sea ice concentration over the Pacific sector of the Arctic Ocean. This study further suggests that the Pacific Decadal Oscillation (PDO) phase change could influence the spatial pattern change in the AD

The Effect of Fish Consumption on Blood Mercury Levels of Pregnant Women

In the present study, we examined the relationship between average fish consumption, as well as the type of fish consumed and levels of mercury in the blood of pregnant women. We also performed follow-up studies to determine if blood mercury levels were decreased after counseling and prenatal education. To examine these potential relationships, pregnant women were divided into two groups: a study group was educated to restrict fish intake, whereas a control group did not receive any prenatal education regarding fish consumption. We measured blood mercury level and performed follow-up studies during the third trimester to examine any differences between the two groups. Out of the 63 pregnant women who participated in our study, we performed follow-up studies with 19 pregnant women from the study group and 12 pregnant women from control group. The average initial blood mercury level of both groups was 2.94 µg/L, with a range of 0.14 to 10.75 µg/L. Blood mercury level in the group who ate fish more than four times per month was significantly higher than that of the group who did not consume fish (p = 0.02). In follow-up studies, blood mercury levels were decreased in the study group but slightly increased in the control group (p = 0.014). The maternal blood mercury level in late pregnancy was positively correlated with mercury levels of cord blood (r = 0.58, p = 0.047), which was almost twice the level found in maternal blood. Pregnant women who consume a large amount of fish may have high blood mercury levels. Further, cord blood mercury levels were much higher than that of maternal blood. Because the level of fish intake appears to influence blood mercury level, preconceptual education might be necessary in order decrease fish consumption

High resolution crystal structure of PedB: a structural basis for the classification of pediocin-like immunity proteins

<p>Abstract</p> <p>Background</p> <p>Pediocin-like bacteriocins, ribosomally-synthesized antimicrobial peptides, are generally coexpressed with cognate immunity proteins in order to protect the bacteriocin-producer from its own bacteriocin. As a step for understanding the mode of action of immunity proteins, we determined the crystal structure of PedB, a pediocin-like immunity protein conferring immunity to pediocin PP-1.</p> <p>Results</p> <p>The 1.6 Å crystal structure of PedB reveals that PedB consists of an antiparallel four-helix bundle with a flexible C-terminal end. PedB shows structural similarity to an immunity protein against enterocin A (EntA-im) but some disparity to an immunity protein against carnobacteriocin B2 (ImB2) in both the C-terminal conformation and the local structure constructed by α3, α4, and their connecting loop. Structure-inspired mutational studies reveal that deletion of the last seven residues of the C-terminus of PedB almost abolished its immunity activity.</p> <p>Conclusion</p> <p>The fact that PedB, EntA-im, and ImB2 share a four-helix bundle structure strongly suggests the structural conservation of this motif in the pediocin-like immunity proteins. The significant difference in the core structure and the C-terminal conformation provides a structural basis for the classification of pediocin-like immunity proteins. Our mutational study using C-terminal-shortened PedBs and the investigation of primary sequence of the C-terminal region, propose that several polar or charged residues in the extreme C-terminus of PedB which is crucial for the immunity are involved in the specific recognition of pediocin PP-1.</p