A simple, label-free and cost effective sensor have been studied for reliable urea/glucose sensing, and common serum analyte detection comparable with market available urea "Assay Kit" is also performed by using SiO 2 and CdSe-ZnS nanoparticles in electrolyte-insulator-semiconductor structure for the first time. Thermally grown SiO 2 membrane has shown lower pH detection limit (0.081) and lowest drift rate (2.9 mV/hr) than those of the sputtering and E-beam deposited SiO 2 membranes. The urea detection at physiological buffer pH 7.4 with sensitivity of ∼1.6 mV/mg.dl −1 at linear range of 6 to 36 mg/dl is shown. The pH detection limit is further reduced (0.074) by using chaperonin protein mediated CdSe-ZnS nanoparticles assembly over SiO 2 surface owing to high pH sensitivity of 55 mV/pH. The sensing mechanism is due to the SiO x content decreased with increasing pH value. This suggests the lower H + ions absorption on the sensing membrane surface, which is observed by X-ray photo-electron spectroscopy. The glucose concentration is detected by using the core-shell CdSe-ZnS nanoparticles through H 2 O 2 sensing because of reduction/oxidation (redox) properties of Zn as well as Zn 2+ ions generation. Due to the high catalytic activity for H 2 O 2 sensitivity, low detection limit of 1 μM is obtained, which will help to detect glucose using this bio-chip in future. The surface charge as well as potential variation of sensing membranes corresponds to ionic concentration can be used for detection of bio-molecules. [3][4][5] Basically, the pH as well as ionic concentration change (H + and OH − ) is major product of enzymatic reaction with analytes (urea, creatinine, acetylcholine, tributyrine, glucose, etc. 6-8 ), which can be measured by using electrolyte-insulator-semiconductor (EIS) structures. Among those analytes, urea and glucose are the very common potential biomarkers for diagnosis of common diseases such as heart failure, diabetes, and kidney injury. [9][10][11][12] Generally, the urea concentration has been detected through pH change. 13,14 They have reported the detection of glucose concentration by measuring the resultant pH change in presence of glucose oxidase. However, small change of pH restricts the glucose measurement at lower concentration and encourages to sense other catalysis product. Hydrogen-peroxide (H 2 O 2 ) is also a catalysis product of selective enzymatic degradation of glucose, cholesterol, lactate, and so on. [15][16][17] In this regards, the sensing membrane in EIS structure has a key role to detect pH or H 2 O 2 for easy use in our daily life with low cost. Consequently, many materials such as SiO 2 , Si 3 N 4 , Al 2 O 3 , HfO 2 , and Ta 2 O 5 have been investigated for pH sensing.18-21 Hal et al. 22 have reported the high intrinsic buffer capacity of SiO 2 at low concentrated basic pH buffer results into higher surface sites and membrane-electrolyte interface reactivity. Due to very simple structure and good interface with substrate, SiO 2 is a reliable membrane to develop urea senso...
Prestressed concrete (PC) box-girders with corrugated steel webs are one of the promising steel concrete composite structures applied to highway bridges. Although the basic structural characteristics including bending, shearing and torsion, etc., have been paid much attention, few researches on the seismic performance of this type of bridges are found, especially when the span of this type of bridges becomes larger and larger. In this paper, the seismic performance of one long-span PC box-girder bridge with corrugated steel webs is studied and compared with a conventional box-girder bridge with concrete webs, based on response spectrum analysis using ANSYS. The results show that, the vertical and transverse displacements of the box-girder with corrugated steel webs are slightly less than those of the box-girder with concrete webs, but the longitudinal displacement reverses, under the same earthquake excitation. The bending moments of representative sections of the box-girder bridge with corrugated steel webs are only about 70% ~ 90% of those of the corresponding conventional PC girder bridge. The results indicate that the box-girder bridge will have better seismic performance if the corrugated steel webs are adopted instead of the concrete webs, but it could also fulfill the tasks such as displacement control which resulted from stiffness reduction.
The environmental deterioration of the subway station and the safety of the personnel evacuation under platform train fire are researched. The critical fire danger condition is proposed and the time calculation method of evacuation is determined. A platform train fire in a subway station is simulated by the Fire Dynamics Simulator software. Then the available egress time can be got by analyzing the fire temperature and smoke concentration change with time. At the same time, the required egress time is studied through theoretical analysis and computer simulation by software Building Exodus. The results showed that smoke exhaust rate is very important to the smoke control under platform train fire. And the stair evacuation ability is the key to the whole evacuation.
This paper concerns the smoke control modes and the critical ventilation velocity when the subway tunnel on fires. The standard for the smoke control mode is making sure the smoke exhausting in the shortest way. The critical ventilation velocity means it is just sufficient to prevent the smoke spreading upstream. The critical velocity in different heat release rates obtained though theoretical analysis and computer simulation. In the end, a simple formula to calculate the critical velocity can be fitting out.
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