A new tri-level switching method for successive approximation register (SAR) analogue-to-digital converters (ADCs) is presented. The proposed switching method enhances the efficiency of ...digital-to-analogue converter switching energy by 93.7% and achieves a 75% reduction in the total capacitor size, compared with the conventional SAR ADC. In addition, the accuracy of the proposed SAR ADC has no dependency on the accuracy of the mid-level reference voltage (Vcm) except in the least significant bit, and the common-mode voltage at the input of the comparator will remain approximately unchanged. Analytical calculations and behavioural simulation results are provided to demonstrate the effectiveness of the proposed switching scheme.
Three hundred and eight samples of rice purchased from retail markets in six different provinces in Iran from March 2012 to January 2013 were surveyed for the presence of ochratoxin A (OTA) using ...enzyme-linked immunosorbent assay. The recovery percentages of OTA from spiked rice samples at concentrations of 5 and 10 ng/g were found to be 85.3% and 86.7%, respectively. Analytical results showed a 9.4% frequency of contamination from total analyzed rice samples with a mean OTA level of 3.60 ± 2.66 ng/g. Concentrations of OTA in positive samples ranged from 0.84 ng/g to 11.37 ng/g, and in 17.3% of contaminated rice samples the concentrations exceeded the maximum tolerance limit set by European regulations for OTA in cereals (5 ng/g). Based on the results of this study, the estimated daily intake of OTA in rice was 0.62 ng/kg body weight/day for Iranian consumers.
Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders ...numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to be degraded over the other catalysts. This enhanced photocatalytic activity of Graphene-supported BiPO4/Ag/Ag3PO4 for all pollutants could be mainly ascribed to the reinforced charge transfer from BiPO4/Ag/Ag3PO4 to RGO, which suppresses the recombination of electron/hole pairs. Besides that, this photocatalyst can be used repetitively with a high photocatalytic activity and no apparent loss of activity occurs. The results reveal that the RGO nanosheets work as a photocatalyst promoter during the photocatalytic reaction, leading to an improved photocatalytic activity.
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•Modification of BiPO4 photocatalyst with Ag/Ag3PO4 and RGO.•BiPO4/Ag/Ag3PO4 based on RGO showed improved photocatalytic performance.•Interface between BiPO4/Ag/Ag3PO4 and RGO increases active sites and charge transfer.•Enhanced photocatalytic activity was ascribed to the reinforced charge transfer.
Taking into account a special class of F(R) gravity, we obtain new Lifshitz-like black hole solutions in three and four dimensions in the context of gravity's rainbow. We discuss the geometric and ...thermodynamic properties of these solutions in the extended phase space and examine the first law of thermodynamics. Besides, we calculate the heat capacity to study thermal stability and possible phase transition. We find that the Lifshitz-like black holes in three dimensional spacetime are thermally stable while four dimensional black hole solutions undergo a van der Waals like phase transition.
In this paper, we work on the topological Lifshitz-like black hole solutions of a special class of vacuum
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gravity that are static and spherically symmetric. We investigate geometric and ...thermodynamic properties of the solutions with due respect to the validity of the first law of thermodynamics. We examine the van der Waals like behavior for asymptotically AdS solutions with spherical horizon by studying the
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diagrams and find a consistent result. We also investigate the same behavior for hyperbolic horizon and interestingly find that the system under study can experience a phase transition with negative temperature.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
► Sonication evenly dispersed titanium oxide nanoparticles in the binders. ► Titanium oxide nanoparticles produced a uniform dispersion of fine inclusions. ► Acicular ferrite structure nucleated at ...Ti-containing inclusions. ► Fine intragranular ferrite enhanced mechanical properties of weld metal.
In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003–0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the electrode coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries.
•Novel Ag3PO4/BiPO4 (AB)–graphene-based photocatalysts were reported.•Photocatalytic degradation mechanism of Atrazine herbicide was investigated.•It was divulged that the photodegradation is ...increased by AB supporting.•Enhanced photodegradation has been obtained by the AB/Cu(tpa).GR nanocomposite.•The unique heterojunction formed by coupling Cu(tpa) with GR caused high activity.
For the first time, we report novel Ag3PO4/BiPO4 (AB)–graphene-based photocatalysts. The fabricated nanocomposites were characterized by various techniques. The photocatalytic properties of the prepared catalysts were evaluated by the photodegradation of Atrazine herbicide under both visible and UV light irradiation. Atrazine concentration was determined using the spectrophotometric method according to the Konig's reaction by monitoring the absorbance at 470nm wavelength during the photodegradation process. Both degradation rate and efficiency using graphene (GR)-based nanocomposites are found to be much better than using pure AB. Atrazine photodegradation displayed that the AB supporting is an important point to become a great photocatalyst for this reaction. Enhanced photodegradation has been obtained by the AB/Cu(tpa).GR nanocomposite. The results showed that the novel synthesized AB/Cu(tpa).GR nanocomposite exhibits a dramatic separation of photogenerated electron/hole pairs. This was accounted for by the improved efficiency of an interfacial charge separation, thanks to the unique heterojunction formed by coupling Cu(tpa) with GR. Chemical oxygen demand of herbicide solution was measured and it posed a good idea about Atrazine herbicide degradation.
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•Modification of TiO2 photocatalyst prepared in ionic liquid medium with Ag2CO3.•Ag2CO3/TiO2/RTIL was synthesized via loading Ag2CO3 on TiO2/RTIL.•Ag2CO3/TiO2/RTIL showed excellent ...photocatalytic activity for AB92 degradation.•Ag2CO3 flower-like particles strongly sensitized TiO2 to absorb visible light.•Ag2CO3 coupling with TiO2 greatly extend the lifetime of charge carriers.
A visible light active Ag2CO3/TiO2/2-hydroxylethylammonium formate (RTIL) nanocomposite has been synthesized via loading Ag2CO3 flower-like particles on TiO2/RTIL by a simple precipitation method. TiO2 nanoparticles were prepared by the modified sol–gel method using 2-hydroxylethylammonium formate (RTIL) as an ionic liquid. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infra red spectroscopy (FTIR) and Diffuse reflectance UV–vis spectroscopy (DRS) techniques. The photocatalytic performance of the synthesized photocatalysts was investigated by the photodegradation of acid blue 92 (AB92) dye under both visible and UV light irradiations. It was divulged that the Ag2CO3/TiO2/RTIL heterostructure noticeably exhibited an improvement in both efficiency and rate of AB92 photodegradation in comparison with both TiO2 samples. The enhanced photocatalytic activity of Ag2CO3/TiO2/RTIL nanocomposite is mainly attributed to the promoted absorption of light and more efficient suppression of charge carrier recombination. The possible mechanism for the improved photocatalytic properties of the Ag2CO3/TiO2/RTIL nanocomposite was also discussed.
The effect of TiO2 nanoparticles in the electrode coating on the impact toughness of three weld metals prepared by shielded metal arc welding was studied. The microstructure, mechanical properties ...and fracture surface morphology of the weld metals were evaluated and the results compared. When the content of TiO2 nanoparticles in the composition of electrode coating was increased, the morphology of ferrite in the microstructure of columnar zone changed from Widmanstatten ferrite to acicular ferrite, finally changing to allotriomorphic ferrite when the amount of TiO2 nanoparticles in the electrode coating was relatively high. Addition of TiO2 nanoparticles was effective in refining the ferrite grain size of the reheated microstructures of weld metals. This effect is attributed to the increased number of nucleation sites on the oxide nanoparticles. The impact toughness of the weld metal was improved by adding TiO2 nanoparticles, especially when a medium TiO2 nanoparticle content was used in the electrode coating. A significant increase in the impact toughness of weld metal was shown to be due to the increased percentage of acicular ferrite and refinement of microstructure.
Most studies investigating the toxicity of zinc oxide nanoparticles (ZnO NPs) focused on the effect of size, whereas exposure concentration and duration remained poorly understood. In this study, the ...effect of acute and sub-acute exposures of ZnO NPs on Zn compartmentalization and biomarkers' expression were investigated in Rutilus rutilus caspicus (Caspian roach) considering various exposure scenarios: i) the assessment of the concentration-response curves and median lethal concentration (LC50); ii) the assessment of the effects of organisms exposed at LC50 value and one tenth of LC50 value of ZnO NPs suspensions for 4 d and 28 d, respectively; iii) the assessment of 14 d depuration period. The same concentrations of ZnSO4 were investigated. The highest Zn accumulation was detected in gill after sub-acute exposure (4.8 mg/L; 28 d) followed by liver, kidney and muscle. In gill, liver and muscle, Zn from Zn NPs accumulated higher concentrations. Depuration (14 d) decreased Zn content in each organ, but no complete removal occurred except for muscle. Biomarkers' activity was significantly over expressed after treatments, but depuration brought back their values to background levels and most effects were related to acute concentrations (48 mg/L; 4 d) and in presence of ZnSO4. Histopathological analyses showed that the exposure to ZnO NPs increased lesions in gill, liver and kidney, with a direct proportionality between alterations and Zn accumulated in the target organs. After depuration, lesions regressed for both ZnO NPs and ZnSO4, but not in a complete way. These data could contribute to increase the knowledge about ZnO NPs risk assessment in aquatic vertebrates, suggesting that the size of ZnO NPs can influence biomarker and histopathological effects.
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•Acute (4 d) and sub-acute (28 d) exposure of ZnO NPs to Caspian roach•ZnO NPs EC50s: 24 h (78 ± 7 mg/L), 48 h (61 ± 5 mg/L), 72 h (53 ± 6), and 96 h (48 ± 3 mg/L)•Zn compartmentalized preferentially in gill and kidney•Depuration brought back all overexpressed biomarkers' activity to background levels•Histopathological alterations were concentrated in gill and kidney.
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