Giardia spp. is a flagellate protozoan that presents two evolution forms, cysts and trophozoites. Cysts are resistant to chlorine, the most employed disinfectant agent in the treatment of water. For this reason, new techniques for the disinfection of waters that contain this parasite are necessary. This work evaluated the efficiency of the disinfection by ozone and ultrasound individually and simultaneously upon wastewater. The data obtained showed that after application, ozone, ultrasound, and combined techniques induced a significant elimination of Giardia spp. cysts. Furthermore, this effect was more accentuated when the two techniques were applied simultaneously. 相似文献
Silver, gold, copper and platinum nanoparticles (NPs) were grown on surfaces in the form of patterns by the exposure of laser radiation onto droplets of metal ion solutions and the aid of a reducing agent. The generation of patterns from metallic NPs was achieved by combining induced growth of NPs and nanostructures by laser incidence directly on surfaces and optical image formation techniques for transferring the patterns. Near-UV (363.8 nm) and visible (532 nm) laser wavelengths were used for the laser-induced growth of NPs into microstructures on glass, quartz, stainless steel, silicon, and gold-on-silicon substrates. The sizes of the patterns formed were on the micrometer scale and the sizes of the transferred patterns were on the millimeter scale. The patterns formed were generated by optical transference of image and interference of laser beams. Ag and Au substrates were highly active in surface enhanced Raman spectroscopy (SERS). The enhanced Raman activity was measured for SERS probe molecules: 9H-purin-6-amine (adenine) and 1,2-bis (4-pyridyl)-ethane analytes on Ag and Au substrates, respectively. The enhancement factors obtained were 1.8×10(5) and 6.2×10(6), respectively. 相似文献
The present paper attempts to empirically study the cognitive impacts of Massive Multiplayer Online Role-Playing Games (MMORPGs) in uncontrolled contexts in light of the Cognitive Mediation Networks Theory, a new model of human intelligence that aims to explain cognition as the result of brain activity combined with the information-processing done by external structures such as tools, social groups and culture. A sample of 1280 students Brazilian high school students answered a form inquiring about socio-demographic information plus the use of computer games, and also was submitted to a short knowledge exam and a mini psychometric test. The findings indicated that, due to their underlying structure and sociocultural nature, MMORPGs are associated to a greater level of insertion into the Digital Age, higher levels of logical-numerical performance, and better scholastic ability. Finally, suggestions are made for future studies on the subject. 相似文献
A novel SBA-16-related synthesis of mesostructured silica containing framework aluminum is reported here. This material was successfully synthesized using aluminum sulphate and the pH-adjusting method. The structural and porosity properties of this novel material were studied by X-ray diffraction and N2 adsorption at 77 K. The Al insertion was determined by 27Al-MAS-NMR and the acidity was monitored by infrared spectroscopy of CO adsorption at 100 K. 相似文献
In order to optimize and improve the design of power devices with improved surge current safe operating area it is necessary to obtain a good correlation between measured and simulated space and time resolved temperature distributions. Therefore, an IR microscope capable of measuring the space and time resolved surface temperature distributions in Si power diodes operating under self-heating conditions has been developed. The minimum detectable spot size is 15 μm, while the signal rise time is detector limited to about 1 μs. The lower temperature detectivity limit is about 10°C over room temperature.
Using this instrument dynamic thermal phenomena in fast recovery 3.3 kV Si power diodes having radiation-induced recombination centers [Proceedings of the 7th EPE, Trondheim, 1997] subjected to 1.2 ms 400–2000 A/cm2 and 0.3–2 ms 2000 A/cm2 current pulses have been studied. The experimental results have been compared to results from 2D device simulations including surface recombination and carrier lifetime temperature dependence. The agreement between experimental and device simulation results (i.e. dynamic IV characteristics and time and space resolved temperature distributions) is very good up to a peak current density of 1500 A/cm2, and a reasonable good one for peak current densities up to 2000 A/cm2 (1.2 ms current pulses). 相似文献
Ultrathin strained-Si/strained-Ge heterostructures on insulator have been fabricated using a bond and etch-back technique.
The substrate consists of a trilayer of 9 nm strained-Si/4 nm strained-Ge/3 nm strained-Si on a 400-nm-thick buried oxide.
The epitaxial trilayer structure was originally grown pseudomorphic to a relaxed Si0.5Ge0.5 layer on a donor substrate. Raman analysis of the as-grown and final transferred layer structures indicates that there is
little change in the strain in the Si and Ge layers after layer transfer. These ultrathin Si and Ge films have very high levels
of strain (∼1.8% biaxial tension and 1.4% compression, respectively), and are suitable for enhanced-mobility field-effect
transistor applications. 相似文献
This document presents new mechanisms for stability assessment in iterative controller tuning. Contrary to the usual approach adopted in robust model identification, the new mechanisms do not rely on plant models, but utilize information from the current closed-loop system to test if a newly designed controller will maintain loop stability. All controllers that satisfy the test are guaranteed to stabilize the actual plant. 相似文献