In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were prepared
using electrospinning technique then calcinated at 800 °C for 2 h. The originality of this study is the addition of boron
to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and
thermal characteristics. The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of
boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers.
XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite
size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping
did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted
in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats
were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were
measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3–La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 59.72 and 39.80 m2/g, respectively. 相似文献
This study aimed to reveal the soil properties in the research area by using various geophysical methods. Physical parameters determining soil characteristics give us a chance to approach how the soil behaves during an earthquake. Thus, precautions can be taken to minimize earthquake damage. Also, safe construction against earthquake effects is important. The studied area is a tectonically and geothermally active area. İzmir Fault zone is passing through the investigation area and trending E–W direction. To investigate soil parameters at this active tectonic region, microtremor method data were recorded and the multichannel analysis of surface waves (MASW) method at 27 profiles was implemented in the study area. Additionally, these methods were supported by the spatial auto correlation (SPAC) method in center spot. Shear wave velocities up to 30 m, soil classification according to the National Earthquake Hazards Reduction Program (NEHRP), site amplification, predominant site period, amplification factor, ground vulnerability index, and shear wave velocity changes up to 300 m were obtained by evaluating the data collected from the applied geophysical methods. VS30 values varied between 700 and 1100 m/s in the southernmost part of the study area, corresponding to a C and B type as soil classification. While the predominant period values were taken as the lowest value of 0.2 s, it was observed to increase up to 5.5 s on the alluvial unit in the northern parts of the study area. The ground vulnerability index, which is directly related to the probability of earthquake damage, was found to be quite high in some parts of the study area. In this paper, we propose microzonation maps for the Balçova district, based on the variation of the soil dynamic parameters.
As a result of increasing population, industrialization, and effluent quality, sludge production has increased worldwide. Organic micropollutants in sludge have become a more critical environmental health concern compared to heavy metals. New sludge disposal regulations limit persistent organic pollutants (POPs) in addition to conventional organic indicators like total and dissolved organic carbon. This study aims at providing a brief review on POP concentration in the sludge in different regions of the world, sludge regulations, assessment of conventional biological sludge stabilization methods according to their ability to remove POPs, and discussions on alternative sludge treatment methods. The impact of sludge treatment unit operations including conditioning, thickening, mechanical and thermal dewatering, and biological and thermal stabilization on sludge management is also discussed in the context of organics. The occurrence and removal of micropollutants such as absorbable organic halogen compounds (AOX), nonylphenol and nonylphenol ethoxylates (NPE), di-2-(ethyl-hexyl)-phthalate (DEHP), dibenzo-p-dioxins and furans (PCDD/F), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) are also evaluated specifically for sludge treatment unit operations. A concise discussion is also included on different drying technologies suitable for drying of sludge. 相似文献
Effects of polymerization parameters are studied to better understand interactions between parameters in stirred-tank polymerization reactors and to derive a regression model correlating polymer particle size and particle-size distribution with agitator speed, agitator diameter, tricalcium phosphate, dodecyl benzene sodium sulfonate concentrations, and mass cycle period. The derived equations give way to prediction of the polymerization conditions in order to obtain desired particle size and particle-size distributions which covers particle sizes between 0.3 and 5 mm. The roles of some other parameters and limiting agitation parameters are also investigated. 相似文献
Optimization studies are performed on the pultrusion of a thermosetting composite. The three-dimensional finite element/nodal control volume procedure developed for simulation and optimization of the process is employed for this purpose. The aim of optimization is to achieve the desired degree of cure with minimum local variations across the pultrudate cross-section. The die-heating environment is optimized for a few cases with different initial temperatures for a glass/epoxy wet preform and for the cooler installed within the pultrusion die near its entrance. The role of these temperature parameters in moderating the optimization constraints is examined. Simultaneous optimization of die-heater temperatures and pull-speed is also considered. It is observed that the temperature overshoot within the composite pultrudate can be reduced and better optimization results can be achieved by a proper choice of a pre-die temperature for the composite and the die-cooler temperature. 相似文献
A dual-task interference paradigm was used to investigate the effect of perceptual effort on recall of spoken word lists by young and older adults with good hearing and with mild-to-moderate hearing loss. In addition to poorer recall accuracy, listeners with hearing loss, especially older adults, showed larger secondary task costs while recalling the word lists even though the stimuli were presented at a sound intensity that allowed correct word identification. Findings support the hypothesis that extra effort at the sensory–perceptual level attendant to hearing loss has negative consequences to downstream recall, an effect that may be further magnified with increased age. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献