Analysis of Slab and Slab Heater Cover in a Compact Endless Cast and Rolling Mill Process using Finite Element Methods

Compact Endless cast and rolling Mill (CEM) processes were developed and used to fabricate steel products such as steel slabs. However, the coiling furnace in this process was very expensive, so a new layout was suggested. As the coiling furnace was removed, the interval among the slab heaters had to be increased. This led to a temperature drop in the slab. The temperature distribution of the slab impacts quality, so new layout was developed. This paper presents a Finite Element Method (FEM) simulation of thermal behavior in the slab employing slab heater covers. All of the simulation results were verified by comparing them with experimental results. The slab moving distance at which the temperature was saturated during the process was determined to consider the steady-state and analyze the temperature distribution of the slab and slab heater. Those results revealed that the efficiency of heat conservation increased by more than 50% using the slab heater cover. Finally, a sensitivity analysis of the slab heater cover was conducted with respect to the cover design. The effects of insulator thickness, the gap distance between the slab and cover, and material parameters such as density, and specific heat were investigated to optimize the design of the slab heater cover to produce the best quality slab.11Ysciescopuskc

Enhanced overall efficiency of GaInN-based light-emitting diodes with reduced efficiency droop by Al-composition-graded AlGaN/GaN superlattice electron blocking layer

AlxGa1-xN/GaN superlattice electron blocking layers (EBLs) with gradually decreasing Al composition toward the p-type GaN layer are introduced to GaInN-based high-power light-emitting diodes (LEDs). GaInN/GaN multiple quantum well LEDs with 5- and 9-period Al-composition-graded AlxGa1-xN/GaN EBL show comparable operating voltage, higher efficiency as well as less efficiency droop than LEDs having conventional bulk AlGaN EBL, which is attributed to the superlattice doping effect, enhanced hole injection into the active region, and reduced potential drop in the EBL by grading Al compositions. Simulation results reveal a reduction in electron leakage for the superlattice EBL, in agreement with experimental results. (C) 2013 AIP Publishing LLC.open1133sciescopu

Antimicrobial peptide from Bacillus subtilis CSB138: characterization, killing kinetics, and synergistic potency

We studied the prospect of synergy between the antimicrobial peptide p138c and non-peptide antibiotics for increasing the potency and bacterial killing kinetics of these agents. The production of p138c was maximized in the late exponential growth phase of Bacillus subtilis CSB138. Purification of p138c resulted in a total of 4800 arbitrary units (AU) with 19.15-fold and 3.2% recovery. Peptide p138c was thermo-tolerant up to 50 °C and stable at pH 5.8 to 11. The biochemical nature of p138c was determined by a bioassay, similar to tricine-SDS-PAGE, indicating inhibition at 3 kDa. The amino acid sequence of p138c was Gly-Leu-Glu-Glu-Thr-Val-Tyr-Ile-Tyr-Gly-Ala-Asn-Met-X-Ser. Potency and killing kinetics against vancomycin-resistant Staphylococcus aureus improved considerably when p138c was synergized with oxacillin, ampicillin, and penicillin G. The minimal inhibitory concentration (MIC) of p138c showed a 4-, 8-, and 16-fold improvement when p138c was combined with oxacillin, ampicillin, and penicillin G, respectively. The fractional inhibitory concentration index for the combination of p138c and oxacillin, ampicillin, and penicillin G was 0.3125, 0.25, and 0.09, respectively. Synergy with non-peptide antibiotics resulted in enhanced killing kinetics of p138c. Hence, the synergy between antimicrobial peptide and non-peptide antibiotics may enhance the potency and bacterial killing kinetics, providing more potent and rapidly acting agents for therapeutic use. [Int Microbiol 20(1):43-53 (2017)]Keywords: Bacillus subtilis · antimicrobial peptides · killing kinetic

Proizvodnja antikomplementnih egzopolisaharida submerznim uzgojem gljive Flammulina velutipes

Seven species of basidiomycetes have been investigated for anti-complementary activity in hot water extracts and ethanol soluble fractions. Since Flammulina velutipes had the most potent activity, culture conditions for its mycelial growth were optimized to increase the production efficiency of anti-complementary exopolysaccharides. The optimal medium composition was (in g/L): galactose 15, sodium nitrate 5, glutamic acid 3, KH2PO4 2.5 and MgSO4·7H2O 0.6. Optimal production of anti-complementary activity was achieved at pH=3.5–5.5 and 25 °C. With these optimal medium and culture conditions, mycelial dry mass was maximized at 3.17 mg/mL after 6 days of cultivation in a 5-liter stirred-tank bioreactor, without pH control. The anti-complementary activity of exopolysaccharides increased sharply after 4 days of cultivation, and showed a high level at 5–6 days of cultivation. A periodate-labile carbohydrate moiety played a leading role in the anti-complementary activity exhibited by exopolysaccharide produced from F. velutipes. Results of tests on the anti-complementary activity in the absence of Ca²+ and immunoelectrophoresis indicated that the mode of complement activation by exopolysaccharide from F. velutipes is via both the classical and alternative pathways and that the activation degree is almost the same in each pathway.Istražena je antikomplementna aktivnost spojeva ekstrahiranih vrućom vodom i etanolom iz sedam vrsta gljiva stapčara. Optimirani su uvjeti uzgoja micelija gljive s najvećom aktivnosti, Flammulina velutipes, radi povećanja proizvodnje antikomplementnih egzopolisaharida. Optimalni sastav podloge bio je (u g/L): galaktoza 15, natrijev nitrat 5, glutamična kiselina 3, KH2PO4 2,5 i MgSO4·7H2O 0,6. Optimalna proizvodnja postignuta je pri pH=3,5-5,5 i 25 ºC. Pri tim uvjetima proizvedena je maksimalna količina suhe tvari od 3,17 mg/L nakon 6 dana uzgoja u bioreaktoru s miješalicom zapremnine 5 L, bez kontrole pH-vrijednosti. Antikomplementna aktivnost egzopolisaharida naglo se povećala nakon 4 dana, te je bila visoka nakon 5-6 dana uzgoja. Šećerni je ostatak, podložan djelovanju perjodata, glavni razlog antikomplementne aktivnosti egzopolisaharida gljive F. velutipes. Rezultati testiranja takve aktivnosti u odsutnosti Ca²+ iona i imunoelektroforeza upućuju na to da se komplementi egzopolisaharida iz F. velutipes aktiviraju klasičnim i alternativnim putem te da je stupanj aktivacije skoro jednak za oba puta