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1.
In this work we prepared NaBiO3 nanopowders via three synthesis methods (sol-precipitation, dehydration and hydrothermal methods). To evaluate and compare the physical properties of the prepared materials X-ray diffraction analysis, BET measurements, UV–vis spectroscopy and TEM were applied. The results showed changes to the NaBiO3 crystallinity, the specific surface area and the particle shape and size, depending on the method of synthesis. To determine the photocatalytic efficiency of the prepared materials, we evaluated the photocatalytic reduction of CO2.  相似文献   
2.
The preparation, characterization, and controlled release of hydroxyapatite (HAp) nanoparticles loaded with streptomycin (STR) was studied. These nanoparticles are highly appropriate for the treatment of bacterial infections and are also promising for the treatment of cancer cells. The analyses involved scanning electron microscopy, dynamic light scattering (DLS) and Z-potential measurements, as well as infrared spectroscopy and X-ray diffraction. Both amorphous (ACP) and crystalline (cHAp) hydroxyapatite nanoparticles were considered since they differ in their release behavior (faster and slower for amorphous and crystalline particles, respectively). The encapsulated nanoparticles were finally incorporated into biodegradable and biocompatible polylactide (PLA) scaffolds. The STR load was carried out following different pathways during the synthesis/precipitation of the nanoparticles (i.e., nucleation steps) and also by simple adsorption once the nanoparticles were formed. The loaded nanoparticles were biocompatible according to the study of the cytotoxicity of extracts using different cell lines. FTIR microspectroscopy was also employed to evaluate the cytotoxic effect on cancer cell lines of nanoparticles internalized by endocytosis. The results were promising when amorphous nanoparticles were employed. The nanoparticles loaded with STR increased their size and changed their superficial negative charge to positive. The nanoparticles’ crystallinity decreased, with the consequence that their crystal sizes reduced, when STR was incorporated into their structure. STR maintained its antibacterial activity, although it was reduced during the adsorption into the nanoparticles formed. The STR release was faster from the amorphous ACP nanoparticles and slower from the crystalline cHAp nanoparticles. However, in both cases, the STR release was slower when incorporated in calcium and phosphate during the synthesis. The biocompatibility of these nanoparticles was assayed by two approximations. When extracts from the nanoparticles were evaluated in cultures of cell lines, no cytotoxic damage was observed at concentrations of less than 10 mg/mL. This demonstrated their biocompatibility. Another experiment using FTIR microspectroscopy evaluated the cytotoxic effect of nanoparticles internalized by endocytosis in cancer cells. The results demonstrated slight damage to the biomacromolecules when the cells were treated with ACP nanoparticles. Both ACP and cHAp nanoparticles were efficiently encapsulated in PLA electrospun matrices, providing functionality and bioactive properties.  相似文献   
3.
The objective of this paper is to introduce the application of Data Dependent Systems (DDS) methodology to the field of ergonomics. Many current techniques in ergonomics utilize static models, which can have significant limitations. DDS is a stochastic modelling and analysis technique that can be used to capture the dynamics of a system through quantitative analysis of the available data. DDS has been successfully applied to the analysis of manufacturing processes and the surfaces generated by those processes. In this research, DDS was used to analyse time-based hand-skin temperature data for the evaluation of two types of glove liners to be used underneath latex gloves. DDS was able to capture the differences between the two glove liners and the two subjects. The implications of the results and the potential of the DDS methodology are discussed.  相似文献   
4.
This paper is concerned with extending models for the maximal covering location problem in two ways. First, the usual 0–1 coverage definition is replaced by the probability of covering a demand within the target time. Second, once the locations are determined, the minimum number of vehicles at each location that satisfies the required performance levels is determined. Thus, the problem of identifying the optimal locations of a pre-specified number of emergency medical service stations is addressed by goal programming. The first goal is to locate these stations so that the maximum expected demand can be reached within a pre-specified target time. Then, the second goal is to ensure that any demand arising located within the service area of the station will find at least one vehicle, such as an ambulance, available. Erlang's loss formula is used to identify the arrival rates when it is necessary to add an ambulance in order to maintain the performance level for the availability of ambulances. The model developed has been used to evaluate locations for the Saudi Arabian Red Crescent Society, Riyadh City, Saudi Arabia.  相似文献   
5.
This paper describes a method for constructingbehavior models of communication networks. The methodutilizes archived quantitative performance data createdby a network management platform to create a Quantitative/Qualitative (Q2)Dynamic System representation. The Q2representation captures the predominant qualitative(symbolic) states of the network, qualitative inputevents and transitions among the states resulting from these events. Thissymbolic model allows the network manager to understandthe current system behavior, and predict future possiblebehaviors. We evaluated the method on two sets of archive data. The method shows promise foruse in network management, including network monitoring,fault detection, prognostication andavoidance.  相似文献   
6.
The development of materials in two-dimensions has been established as an effective approach to improve their thermoelectric performance for renewable energy production. In this article, we generated monolayers of the orthorhombic structured lead-chalcogenides PbX (X = S, Se, and Te) for room-temperature thermoelectric applications. The Density functional theory and semiclassical Boltzmann transport theory-based computational approaches have been adopted to carry out this study. The band structures of PbX monolayers exhibited narrow indirect bandgaps with a large density of states corresponding to their bandgap edges. Accordingly, substantial electrical conductivities and Seebeck coefficients have been obtained at moderate level doping that has caused significant thermoelectric power factors (PFs) and figures-of-merit (zT) ~1. The single-layered PbX showed anisotropic dispersion of electronic states in the band structure. A relatively lighter effective mass of charge carriers has been extrapolated from the bands oriented in the y-direction than that of the x-direction. As a result, the electrical conductivities and PFs have been observed larger in the y-direction. The optimum PFs recorded for single-layered PbS, PbSe, and PbTe in y-direction amounts to 9.90 × 1010 W/mK2s at 1.0 eV, 10.40 × 1010 W/mK2s at 0.82 eV, and 10.80 × 1010 W/mK2s 0.66 eV respectively. Moreover, a slight increase in p-type doping is found to improve the x-component of the PF, whereas n-type doping has led to improvement in the y-component of PF. Our results show an improved thermoelectric response of PbX monolayer (PbTe in particular) than their bulk counterparts reported in the literature, which indicates the promise of PbX monolayers for nanoscale thermoelectric applications at room temperature.  相似文献   
7.
8.
Silver nanoparticles doped in polyvinyl alcohol (AgNps/PVA) were synthesized via polymer-promoted reductive reaction of AgNO3 and PVA under time-dependent exposure to UV radiation. The AgNps/PVA composites were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction, UV–Vis spectroscopy, and transmission electron microscopy to describe the structure, nuclearity, and distribution of Ag Nps within the PVA matrix. The UV–Vis spectrum of AgNps/PVA exhibited a broad surface plasmon absorption around 425–443 nm which originated from the formation of Ag NPs. Surface analysis by XPS indicated that the Ag NPs were grown solely on the PVA surface at UV exposure time of 2 h (2.0AgNPs/PVA). Increasing the UV exposure time to 4 h will cause the transformation of metallic nanosilver to oxidized nanosilver. UV–Vis absorption spectra were in situ recorded to follow the synthesis of Prussian blue (PB) on 2.0AgNPs/PVA (PB@2.0AgNPs/PVA). The colloidal dispersion of 2.0AgNPs/PVA in an acidic medium containing free Fe(III) ions and potassium hexacyanoferrate(III) revealed an additional band centered at 720 nm due to the intermetal charge-transfer absorbance of the polymeric Fe(II)-C-N-Fe(III) of the PB@2.0AgNPs/PVA nanocomposite. Control experiments were shown to involve a spontaneous electron transfer reaction between 2.0AgNPs/PVA and Fe(III) ions, with a concomitant decomposition of hexacyanoferrate(III) and formation of PB was observed. Moreover, IR gave clear cut evidence for the synthesis of PB@2.0AgNPs/PVA from the appearance of a band for the cyano group at 2090 cm?1.  相似文献   
9.
Abstract

This paper explores automatic generation control (AGC) of a more realistic 2-area multi-source power system comprising hydro, thermal, gas, and wind energy sources-based power plants in each control area. The wind power plants (WPPs) have been growing continuously worldwide due to their inherent feature of providing eco-friendly sustainable energy. But, operations of WPPs are associated with system stability problems due to lack of inertia. However, WPPs do not participate in the elimination of mismatch between generation and demand by AGC but disturbance can be injected by the WPPs due to the stochastic nature of wind energy. An optimal controller based on full state feedback control theory is designed to conduct the study. The system dynamic performance analysis is carried out for 1% step load disturbance in corresponding control areas. It is observed that the system dynamic graphs of deviation in area frequency and tie-line power are significantly improved with the implementation of optimal AGC controller compared to GA tuned classical controller. It has also been shown that the WPPs aid the increase in load disturbance when the input wind power reduces but it negates the effect of increase in load disturbance for increase in wind energy to the WPPs.  相似文献   
10.
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