Search Results (4)

Historically, the photocatalytic efficacy of graphitic carbon nitride (g-C₃N₄) has been constrained by a rapid charge recombination rate and restricted sensitivity to visible light. To overcome these limitations and enhance the performance of g-C₃N₄, the strategic formation of heterojunctions with semiconductor materials is deemed the optimal approach. The present study employed a facile sonication-assisted pyrolysis method to synthesize a g-C₃N₄@ZrO₂ nanocomposite photocatalyst. This hybrid material was characterized extensively using a comprehensive suite of analytical techniques, including XRD, SEM, EDX, FTIR, and UV-Vis DRS. A comparative analysis of photocatalytic applications under identical conditions was conducted for all synthesized materials, wherein they were subjected to UVc light irradiation. The photocatalytic degradation of various dye models, such as MB, EY, and a combination of dyes, was assessed using the prepared nanocomposites. The g-C₃N4@ZrO₂ photocatalysts showcased superior photocatalytic performance, with a particular variant, g-CNZ₆, exhibiting remarkable activity. With a bandgap energy of 2.57 eV, g-CNZ₆ achieved impressive degradation efficiencies of 96.5% for MB and 95.6% for EY within 40 min. Following previous studies, the superoxide radical anions (O₂⁻. and h⁺) were largely accountable for the degradation of MB. Therefore, the observed efficacy of the g-C₃N4@ZrO₂ nanocomposite photocatalyst can be attributed to the increased generation of these reactive species. Full article

Improving building performance through reducing negative environmental impacts can be achieved by greening existing buildings (GEB), which is considered a very important sustainability process. Due to the risky and uncertain nature of the process of GEB, a growing amount of attention should be given to eliminating the effects of risks on GEB. This research aims to identify most expected risk factors related to GEB, as well as to evaluate their effects through calculating risk factor characteristics, such as risk factor presence (RFP), impact on the GEB process (IGEB), and impact on building performance in the long run (IBP), as new indices describe these risks. Sixty-six risk factors were categorized in seven risk groups related to the economic aspect, social aspect, environmental aspect, managerial aspect, sustainability operation, sustainable design, and renovation. Moreover, a fuzzy model for risk analysis was developed to combine the multi-effects of the aforementioned three risk factor characteristics in one index representing the risk factors’ overall importance. The model was applied and verified for data collected in Saudi Arabia. The results of this study showed that the most important risk group is the greening process of environmental control, while the least important is the greening process of renovation and construction. Using the proposed model improved the results of evaluating risks affecting GEB through merging the multi-effects of risk factor characteristics. The results and analysis proved that the most important key risk factors were environmental in nature. An intricate relationship of the impacts on the GEB process and building performance with the overall importance of the risk factors was clearly found. The decision makers who deal with greening projects in Saudi Arabia should be aware of the key risks identified in this study. The proposed methodology and model can be easily applied to other countries to help decision makers in evaluating their GEB projects, as well as comparing more greening projects based on risk analysis. Full article

A number of 5-aryl-1-methyl-4-nitroimidazoles 5a-f have been synthesized in good yields by the Suzuki coupling reaction between 5-chloro-1-methyl-4-nitroimidazole (3) and arylboronic acids 4a-f, aided by dichlorobis-(triphenylphosphine)palladium(II), K₂CO_3, and tetrabutylammonium bromide in water at 70-80 °C. Compounds 5a-f were characterized by elemental analysis, NMR and MS spectral data. On the basis of in vitro screening data, 5-(3-chlorophenyl)-1-methyl-4-nitro-1H-imidazole (5f)exhibited potent lethal activity against Entamoeba histolytica and Giardia intestinalis with IC₅₀ = 1.47 µM/mL, a value lower by a factor of two than that of the standard drug, metronidazole. The boosted activity of 5f was not accompanied by any increased cytotoxicity.The rest of the series also exhibited potent antiparasitic activity with IC₅₀ valuesin the 1.72-4.43 µM/mL range. The cytotoxicity of the derivatives 5c and 5e was increased compared to the precursor compound, metronidazole, although they remain non-cytotoxic at concentrations much higher than the antiparasitic concentration of the two derivatives. Full article

Three novel new compounds derived from antiparasitic precursors have been synthesized and tested for their antiamoebic and antigiardial activities. The condensation of 2-(2-methyl-5-1H-nitroimidazolyl)ethylamine (6) with 5-nitro-2-furylacrylic acid (7) gave 3-(5-nitrofuran-2-yl)-N-[2-(5-nitroimidazol-1-yl)ethyl]acrylamide (8). Condensation of 7 with 7-chloro-4-(piperazin-1-yl)quinoline (9) afforded 1-[4-(7-chloroquinolin-4-yl)piperazin-1-yl)-3-(5-nitrofuran-2-yl)propenone as a mixture of two isomers; 10-a (the E-isomer) and 10-b (the Z-isomer). In addition, the reaction of 9 with 1-(2-bromoethyl)-2-methyl-5-nitroimidazole (11) in the presence of K₂CO₃ and NaI yielded 7-chloro-4-(4-[2-(5-nitroimidazol-1-yl)ethyl]-piprazin-1-yl)quinoline (12). On the basis of preliminary screening data for these new compounds, compound 12 exhibited potent lethal activities against Entamoeba histolytica and Giardia intestinalis; its IC₅₀ ( about 1 µM) was lower, at least by a factor of five, compared to the standard drug, metronidazole. In addition, the IC₅₀ of compound 12 against the tested parasites is 600 times below that against Hep-2 and Vero cells. Compounds 8 and 10-a also exhibited potent or moderate antiamoebic and antigiardial activities with IC_{50 values} of about 5.5 µM, and 140 µM, respectively, against the tested parasites. These two hybrid molecules, 8, 10-a, were also non-cytotoxic at the lethal concentrations against the parasites. Full article