The unpleasant odor that appears in the industrial and adjacent waste processing areas is a permanent concern for the protection of the environment and, especially, for the quality of life. Among the many variants for removing substance traces, which give an unpleasant smell to the air, membrane-based methods or techniques are viable options. Their advantages consist of installation simplicity and scaling possibility, selectivity; moreover, the flows of odorous substances are direct, automation is complete by accessible operating parameters (pH, temperature, ionic strength), and the operation costs are low. The paper presents the process of obtaining membranes from cellulosic derivatives containing silver nanoparticles, using accessible raw materials (namely motion picture films from abandoned archives). The technique used for membrane preparation was the immersion precipitation for phase inversion of cellulosic polymer solutions in methylene chloride: methanol, 2:1 volume. The membranes obtained were morphologically and structurally characterized by scanning electron microscopy (SEM) and high resolution SEM (HR SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectrometry (FTIR), thermal analysis (TG, ATD). Then, the membrane performance process (extraction efficiency and species flux) was determined using hydrogen sulfide (H2S) and ethanethiol (C2H5SH) as target substances.
An important tributary of the Danube River, the Olt River, was characterized in its middle and lower catchment in terms of volatile organic compounds (1,2 -dichloroethane and perchlorethylene) and volatile aromatic hydrocarbons (benzene, toluene and xylene isomers) to better assess their transfer in the environmental compartments (air, water, sediment and biota). A fugacity based calculation model was applied to establish the bio-concentration factors (BCFs) that relates the compounds concentration from sediment-, water- or air- to the biota based on experimental data. Thus, conclusive suggestions can be achieved for a rapid preliminary risk assessment as support tool for the preventive measures in the contaminated areas resulting from accidental chemical discharges or continuous pollution. For thus, water and sediment samples were collected and analyzed by gas chromatography for the selected compounds, the results being applied as input data for the model. The modeling revealed the tendency of the investigated compounds to transfer from water section to air. Simulated values obtained for section sediment as validation tool, are comparable and compatible with the values obtained by analytical measurements, and thus a rapid estimation of the pollution level in the environmental compartment of interest can be achieved based on a limited number of analytical measurements. Thus, by applying the fugacity model to estimate a pollution footprint, conclusive indications for a rapid environmental risk assessment can be achieved.
The massive scale of industrial development has resulted in environmental pollution in general and water contamination in particular. It is important at the present time to treat water for the purpose of eliminating or reducing pollutants, especially toxic pollutants, such as phenol compounds. In this study, zeolite (4A) was prepared firstly from the available and cheap materials using an inclined rotary disk. Then, physical, mechanical, and chemical properties were also studied. Experiments were conducted to determine these properties using local clay and the following results were obtained: Zeolite (4A) 70% and clay 30%, the time of calcination 3 h at a temperature of 850��C, breakage resistance of 17 Ib pounds, surface area 530-590 m2/g, grinding value 14% and moisture absorption ratio 30%. The prepared zeolite (4A) was used in the process of removing phenolic compounds (chlorophenol, nitrophenol) by the adsorption method. Different amounts of prepared zeolite (5g/l and 10g/L) will be used in the treatment process and different concentrations (2mg/L, 5 mg/L and 10 mg/L) of the pollutants Nitrophenol and Chlorophenol were used in the contaminated water tested. The removal process was carried out with a mixing speed of 200 rpm and pH (7.5-8.5). From the results of this study, we note that the highest percentage of Nitrophenol removal is (84.8%) when using an amount of zeolite (5g) and highest percentage of Nitrophenol removal is (95.5%) when using an amount of zeolite (10g) while that the highest percentage of Chlorophenol removal is (78.3%) when using an amount of zeolite (5g) and highest percentage of Chlorophenol removal is (0.894) when using an amount of zeolite (10g) it could be deduced that the percentage of the removal of nitrophenol was higher than that of chlorophenol because its solubility of chlorophenol in water is higher than the solubility of Nitrophenol.
In the contemporary dentistry the highly esthetic prosthetic restorations are readily achievable knowing the patient's expectations, communicating effectively with the dental technician and selecting appropriate materials and technologies. One of the important factors that influence the ceramic resistance in the metal-ceramic restorations is the design of the framework. A design of the framework that provides support for cusps may therefore be advantageous in preventing the fracture of the plating ceramics. The outer geometry of the metal-ceramic restorations is strongly defined by anatomical and physiological circumstances. Although a change in the framework design does not necessarily affect the external form of the restoration, a thicker frame automatically implies a thinner layer of veneering and vice versa.In this study we present a series of clinical cases in which we have used different techniques for modeling the wax patterns of the future metal structure according to several clinical features. There are presented techniques for obtaining the layouts for the metallic structures of partial or total esthetic metal-ceramic restorations, dental supported or implant supported, classic techniques and innovative techniques that allow previewing the final aspect of restoration and the transfer of clinical data for a highly functional prosthesis.The wax patterns are exact copies of future prosthetic parts, so should be done with great care. The ergonomics had made place also at this level currently existing a multitude of techniques and materials that facilitate the dental technician’s work.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.