Papers by Keyword: Ultrasound

Abstract: Concrete is today the most widely used building material in the world; it has experienced a real boom in its association with steel in reinforced concrete. The mechanical and chemical complementarity between these two materials has made it possible to build economically and reliably the structures required for all human activities, hence sustainability becomes both a requirement and a major concern of manufacturers. It is therefore essential that the functions of the reinforced concrete are not reduced and that its properties are not altered. However, it is a reactive and a porous material able to the physical and chemical degradations in contact with its environment, due to a chemical reaction between these two media.In this work, we are interested in characterizing and monitoring the ions chloride penetration in reinforced concrete. For this purpose, specimens of the reinforced slab type are made with a composition standardized according to the DREUX-Gorisse method, and we have followed the concrete’ mechanical characteristics evolution in parallel with the immersion / drying cycles’ slab in the sea water. This development was followed with an ultrasound device for a period of about thirty two (32) months. After this period, the reinforcements’ electrochemical behavior by cyclic voltammetry, in these slabs was studied in order to determine the corrosion rate.The results indicated that there is a relationship between the concrete’ strength and the state of its reinforcements with the surrounding environment. On the other hand, the coating thickness is a fundamental parameter of the reinforced concrete durability which makes it possible to lengthen the corrosion initiation.

Abstract: Curcumin has biological properties because of its special characteristic of structure. Mono-ketone analogs curcumin show a better pharmacokinetics than curcumin itself. Curcumin analogs 1 and 2 were synthesized from 3,5-dimethoxybenzaldhyde and acetone (analog 1) and cyclohexanone (analog 2) under ultrasound irradiation at room temperature for 15-30 minutes and the yield of each analogs is 82.40% and 77.52%. Analog curcumin 1 and 2 were tested the inhibitory activity towards α-amylase enzyme with acarbose as a positive control. The inhibitory activity of α-amylase is determined by measure the descent of iodine-starch complex using Tecan Spark-Multimode Microplate Reader. Acarbose gives 42.9% inhibition activity at 12.5 mg/L concentration whereas analog 1 shows an inhibition activity 48.5% at 50 mg/L concentration and analog 2 gives 45.8% inhibition activity at 25 mg/L concentration. Hence analog 1 and analog 2 has a potential as an inhibitory agent of α-amylase which performs a better activity than acarbose.

Abstract: Chemosensor of coumarin-chalcone (2) derivative has been synthesized and tested for chicken spoilage indicator. The compound (2) was synthesized from the reaction of 3-acetyl-2H-chromen-one (1) and vanillin with reflux and ultrasonic irradiation methods. The compound (2) exhibited quick and obvious color in sensor label for amines from yellow to dark yellow. Application to detect spoiled chicken showed that color of compound (2) changed at 12 h and 6 d in room and chiller temperature respectively. Thus, compound (2) can be used efficiently for decayed chicken detection.

Abstract: Three curcumin analogs of dimethylaminobenzaldehyde derivatives, i.e., A, B and C were synthesized using a green method using the ultrasound-assisted technique, and the process was compared to the conventional method. The improvements were achieved by decreasing the reaction time from hours to minutes and giving the higher yields of the products. The products were tested as an antidiabetic agent by treated them as an inhibitor for α-amylase activity. The result of α-amylase inhibition showed that curcumin analogs (A, B, C) have high inhibition (77.06; 76.59; 78.34%) with IC₅₀value 23.64; 1.36; and 5.93 μg/mL, respectively. Meanwhile, the α-amylase inhibition of the combination between curcumin analog and ferulic acid showed that the curcumin analog C gave the highest inhibition level of 95.94% with IC₅₀ 13.38 μg/mL. The combination of curcumin analog A and ferulic acid has a strong synergistic effect with a combination index (CI) value of less than 1, i.e., 0.33. These curcumin analogs are quite potent in inhibiting the activity of α-amylase so that it can be a good candidate for antidiabetic drugs.

Abstract: In aluminium preparation by means of electrolysis of alumina-cryolite melts one of the largest-scale type of industrial waste is spent pot lining (SPL). Chemical composition of SPL carbon part consists of various elements with fluorine as the main one. One of the solutions of the problem of reducing environmental load by means of storage of waste of this type is extraction of valuable components (such as fluorine), that can be used further for preparation of fluorine entities (cryolite, calcium fluoride), that are brought back to electrolytic process. We have held experiments on extracting fluorine from SPL by caustic liquor leaching under effect of ultrasonic oscillations on a pulp, increasing the degree of fluorine solubilization. By means of mathematical planning method of a factor experiment cross impact of three leaching parameters was stated, maximum concentration of fluorine ions in the solution (20.21 gr/dm³) was achieved in following conditions: NaOH concentration - 2%, solid-liquid ration - 6:1, process length - 90 min. The degree of fluorine extraction from SPL is 69.87%.

Abstract: State of the art of in-situ analysis on grain structure of metals during thermal and stress treatment is done by observation of the probe in a thermomechanical treatment system. Potential analysis methods are high energy x-ray scattering (e.g. in a synchrotron) or laser-ultrasonics (LUS). The most commonly used thermomechanical system, is the so called “Gleeble” from Dynamic Systems Inc., which is able to heat and load the material in a quite fast manner with extremely high heating rates, very high forces and fast force changes. There is a wide area of research and applications, though, where these capabilities are not fully required, a less complex deformation-and quenching dilatometer would often be sufficient. In this paper we will show the implementation of a LUS system in such a dilatometer and compare it to the “all inclusive” Gleeble system, pointing out benefits and downsides on different aspects, like the technical specifications, the needed footprint and more. A sketch of the full system and the beam path will show the general idea on the implementation of the LUS system into the dilatometer. We will also present first results of a thermal treatment on a metal sample suited for grain structure and phase transition analysis.

Abstract: To stabilize the geometric parameters of the elastic plates during production, the "aging" method is used, which has low performance, and as an alternative to which the method of ultrasonic stabilization is developed. The essence of ultrasonic stabilization is to create the elastic strain applied via the static load in the central part of the plate by the tool, and to communicate ultrasonic vibrations, which lead to the relaxation of residual stresses and stabilization of the geometric parameters of the plate. Analytical expressions are obtained in order to calculate technological parameters of the ultrasound processing. Computer simulation was held on the basis of the theoretical and analytical models, which has allowed to identify and to visualize the dependence of residual stress and plate deformation on the duration and amplitude of ultrasonic vibrations. On the basis of the obtained dependences it was found that the vibrational amplitude should be reduced to reduce the residual strain, however this increases the processing time. Thus, the greater the amplitude of the ultrasonic vibrations is, the more intense the reduction of residual stresses is. Intensive changes of the residual strain and stresses in the first few seconds are characterized by high efficiency of ultrasonic stabilization, which is recommended as a replacement for the aging method.

Abstract: The investigations of ultrasound Rayleigh wave parameters changing depending on localized plastic strain in AlCu4MgSi alloy and austenitic stainless steel AISI 304 are presented in this paper. Measurements of the ultrasound parameters and localized strain bands motion were carried out in-situ during the tensile tests of the specimens at the constant rate and room temperature. It has been found that the measurement of ultrasound velocity allows detecting the initiation of a localized strain band and its location relative to the acoustic measurement area independently of the deformation mechanism.

Abstract: Novel rice gels were prepared with different compositions of rice starch (RS) powder and solution of additives. The formulations of gels were composed of RS powder, liquid glycerol, and additives by aqueous solution method. Five solution with different concentration of RS powder (0.5 g, 1 g, 1.5 g, 2 g and 2.5 g). These solutions were dried in electric oven at 65°C for 4 hours. The physical and chemical properties of rice gel characterized were: turbidity, viscosity, smell, irritation, cleaning, pH and moisture content of these gels have been monitored. Results showed that 2 g of RS powder was optimized formulation which had turbidity, high viscosity, pleasant smell, non-irritation and easy to clean. The pH value of this gel was 6.92 ± 0.01 and the moisture content was 0.21 ± 0.07 % which was equivalent to commercial standard of ultrasound gel. These results concluded that the application of RS in gel ultrasound was safe and effective for replacement commercial gel ultrasound. This gel should be studied on image quality in ultrasound examination next step.

Abstract: The research presents a comparative study regarding the optimization of two bioscouring treatments applied on 50 % of flax+50 % of cotton blended material in presence and absence of the ultrasound energy The treatments optimization was made by using a central, rotatable second order compound program with two independent variables: enzyme concentration and treatment time. The data obtained after determination of the weight loss of the treated samples fabrics were used afterwards for the bioscouring treatments optimization.