Numerical investigation of the effect of dual frequency sonication on stable bubble dynamics.

A computational study aiming to simulate an oxygen single acoustic bubble oscillation under a dual-frequency sonication was presented in this paper. The non-linear response of the bubble to the superposition of two fields of ultrasonic waves was investigated through dynamics parameters, collapse ratios and average velocities. The main goal of this analyze is to link the properties of the wave resulting from the dual-frequency excitation to the dynamics behavior of the bubble.

Conservation of stored food using plant's extracts. Effect of oregano (Origanum vulgaris) essential oils on the reproduction and development of flour moth (Ephestia kuehniella).

In the search for effective methods of biological control of stored products insect-pests, the essential oil of Origanum vulgaris was extracted using Clevenger apparatus and tested on reproduction and mortality of flour moth Ephestia kuehniella. Bio-insecticide works with a double action mechanism; administered by inhalation in pupae, essential oil affects their pupal development. It also disrupts the reproduction of exuviated adults by extending the preoviposition period and reducing the period of egg laying and fecundity because fecundated females cannot live more than four days compared to control group.

Depth effect on the inertial collapse of cavitation bubble under ultrasound: Special emphasis on the role of the wave attenuation.

Acoustic cavitation concentrates and releases a very large amount of energy in localized areas, which can be used for many physical and chemical processes. Even though acoustic cavitation has been studied widely for decades in lab-scale sonoreactors, only few studies have been devoted to characterize this event in big-scale sonoreactors, where the liquid depth may have a critical influence on the bubble collapse. The present computational study furnished numerical data about the effect of depth (z = 0-10 m) on acoustic cavitation with special focus on the role of attenuation of the ultrasound wave on the dramatic conditions developed within bubbles at collapse.

Synthesis, Spectroscopic Characterization, and Antibacterial Evaluation of Novel Functionalized Sulfamidocarbonyloxyphosphonates.

Several new sulfamidocarbonyloxyphosphonates were prepared in two steps, namely carbamoylation and sulfamoylation, by using chlorosulfonyl isocyanate (CSI), α-hydroxyphosphonates, and various amino derivatives and related (primary or secondary amines, β-amino esters, and oxazolidin-2-ones). All structures were confirmed by ¹H, C, and P NMR spectroscopy, IR spectroscopy, and mass spectroscopy, as well as elemental analysis. Eight compounds were evaluated for their antibacterial activity against four reference bacteria including Gram-positive (ATCC 25923), and Gram-negative (ATCC 25922), (ATCC 700603), (ATCC 27853), in addition to three clinical strains of each studied bacterial species.

Insights into numerical simulation of controlled ultrasonic waveforms driving single cavitation bubble activity.

A computational study treating cavitation phenomenon within a single bubble undergoing various controlled ultrasonic waveforms is presented in this paper. Numerical simulations using sinusoidal, square, triangular and sawtooth waves crossing an aqueous media, saturated with oxygen, are conducted upon various operational conditions of frequency and amplitude. Bubble radius, temperature and pressure were estimated over time for 64 combined cases.

Ultrasonic waveform upshot on mass variation within single cavitation bubble: Investigation of physical and chemical transformations.

The mechanical disturbance created by an ultrasonic wave travelling through a liquid medium induces the formation of cavitation that oscillates due to rarefaction and compression of the wave. The duration and the magnitude of the pressure applied by the ultrasonic wave at each instant would generate a specific impact on the variation of the bubble radius, the temperature, the pressure and the mass inside it. In this paper, a numerical study is conducted to simulate four waveforms (sinusoidal, square, triangular and sawtooth) travelling an aqueous media saturated with oxygen with an amplitude of 1.

Probing the radical chemistry and the reaction zone during the sono-degradation of endocrine disruptor 2-phenoxyethanol in water.

Sonochemical degradation at 600 kHz of 2-phenoxyethanol (PhE), an endocrine disrupting compound, was performed in the presence of several organic additives, namely: 2-propanol, Triton X-100 and sucrose, of different volatilities to obtain detailed information on the reaction zone and the oxidation pathway of this priority emerging water contaminate. It was found that sonication at 600 kHz and 120 W completely remove PhE (10 mg L) from aerated solutions within 100 min of irradiation. Very little removal of PhE (∼7%) and low accumulation of HO took place in the presence of adequate amount of 2-propanol, indicating that reaction with OH radical outside the bubble is the major degradation pathway of PhE.

Influence of reactions heats on variation of radius, temperature, pressure and chemical species amounts within a single acoustic cavitation bubble.

The scientific interest toward the study of acoustic bubble is mainly explained by its practical benefit in providing a reactional media favorable to the rapid evolution of chemical mechanism. The evolution of this mechanism is related to the simultaneous and dependent variation of the volume, temperature and pressure within the bubble, retrieved by the resolution of a differential equations system, including among others the thermal balance. This last one is subject to different assumptions, some authors deem simply that the temperature varies adiabatically during the collapsing phase, without considering the reactions heat of the studied mechanism.

Acoustic cavitation in 1-butyl-3-methylimidazolium bis(triflluoromethyl-sulfonyl)imide based ionic liquid.

In this work, a comparison between the temperatures/pressures within acoustic cavitation bubble in an imidazolium-based room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium bis(triflluoromethyl-sulfonyl)imide ([BMIM][NTf]), and in water has been made for a wide range of cavitation parameters including frequency (140-1000kHz), acoustic intensity (0.5-1Wcm), liquid temperature (20-50°C) and external static pressure (0.7-1.

Efficient degradation method of emerging organic pollutants in marine environment using UV/periodate process: Case of chlorazol black.

Sea has historically been subject to high anthropogenic pressures of direct and indirect loads of emerging organic pollutants (EOPs) from intensive industrial and agricultural activities. Photoactivated periodate (UV/IO) is an innovative oxidation technique that was never tested in seawater as pollutants matrix. In this work, we attempted to investigate the treatment of seawater contaminated with chlorazol black (CB) dye, as a model of EOPs, using photoactivated periodate process.

Numerical estimation of ultrasonic production of hydrogen: Effect of ideal and real gas based models.

Based on two different assumptions regarding the equation describing the state of the gases within an acoustic cavitation bubble, this paper studies the sonochemical production of hydrogen, through two numerical models treating the evolution of a chemical mechanism within a single bubble saturated with oxygen during an oscillation cycle in water. The first approach is built on an ideal gas model, while the second one is founded on Van der Waals equation, and the main objective was to analyze the effect of the considered state equation on the ultrasonic hydrogen production retrieved by simulation under various operating conditions. The obtained results show that even when the second approach gives higher values of temperature, pressure and total free radicals production, yield of hydrogen does not follow the same trend.

CAL-B-Catalyzed deacylation of benzylic acetates: Effect of amines addition. Comparison of several approaches.

Herein, we report an efficient enantioselective cleavage of the acyl-moity of some secondary benzylic acetate derivatives catalyzed by lipase B from Candida antarctica (CAL-B) in the presence of triethylamine, as additive, in non aqueous media. The influence of the hydrophobicity of two solvent, the basicity of three amines and the amount of CAL-B were studied in the presence/absence of molecular sieves 4Å. The best results in term of selectivity are achieved using the triethylamine as basic additive and in that case, the reactivity is only best at low conversion.

Computational study of state equation effect on single acoustic cavitation bubble's phenomenon.

Many models have been established to study the evolution of the bubble dynamics and chemical kinetics within a single acoustic cavitation bubble during its oscillation. The content of the bubble is a gas medium that generates the evolution of a chemical mechanism governed by the internal bubble conditions. These gases are described by a state equation, linking the pressure to the volume, temperature and species amounts, and influencing simultaneously the dynamical, the thermal and the mass variation in the cavitation bubble.

Improvement of sonochemical degradation of Brilliant blue R in water using periodate ions: Implication of iodine radicals in the oxidation process.

In this paper, the effect of periodate (IO) on the ultrasonic degradation at 300kHz of Brilliant Blue R (BBR), an organic dye pollutant, was investigated. The experiments were realized in the absence and presence of periodate for various operating conditions including initial solution pH (2-8) and delivered ultrasonic power (20-80W). It was found that periodate greatly enhanced the sonochemical degradation of BBR.

Preparations based on minerals extracts of Calicotome villosa roots and bovine butyrate matter: Evaluation in vitro of their antifungal activity.

Objective: The use of preparations based on minerals extracts of Calicotome villosa and butter is born from the misuse of drugs without specific microbiological analyzes. Seventeen different preparations were performed. The antibacterial and antifungal activities were determined on five bacteria and two fungi strains respectively.

Persulfate-enhanced sonochemical degradation of naphthol blue black in water: Evidence of sulfate radical formation.

This work explores the effect of persulfate (PS) on the sonochemical degradation of organic pollutants taking naphthol blue black (NBB), an anionic diazo dye, as a substrate model. The sonolytic experiments were conducted in the absence and presence of PS under various experimental conditions including acoustic power (10-80W), frequency (20 and 585kHz) and saturating gas (argon, air and nitrogen). Experimental results showed that PS decomposition into sulfate radical (SO) takes place by sonolysis and increasing PS concentration up to 1g/L would result in an increase in the NBB degradation rate.

Solvability of a boundary value problem at resonance.

This paper concerns the solvability of a nonlinear fractional boundary value problem at resonance. By using fixed point theorems we prove that the perturbed problem has a solution, then by some ideas from analysis we show that the original problem is solvable. An example is given to illustrate the obatined results.

Moving window KPCA with reduced complexity for nonlinear dynamic process monitoring.

This paper proposes an improved Reduced Kernel Principal Component Analysis (RKPCA) for handling nonlinear dynamic systems. The proposed method is entitled Moving Window Reduced Kernel Principal Component Analysis (MW-RKPCA). It consists firstly in approximating the principal components (PCs) of the KPCA model by a reduced data set that approaches "properly" the system behavior in the order to elaborate an RKPCA model.

The size of active bubbles for the production of hydrogen in sonochemical reaction field.

The sonication of aqueous solution generates microscopic cavitation bubbles that may growth and violently collapse to produce highly reactive species (i.e. OH, HO2 and H2O2), hydrogen and emit light, sonoluminescence.

Antihyperglycemic and antidiabetic effects of Ethyl (S)-2-(1-cyclohexylsulfamide carbamoyloxy) propanoate in streptozotocin-induced diabetic Wistar rats.

In this study, we examined the antihyperglycemic and antidiabetic effects of a novel synthesized molecule, the Ethyl (S)-2-(1-cyclohexylsulfamide carbamoyloxy) propanoate (ESP1b), in streptozotocin (STZ)-induced diabetic Wistar rats. Experimental diabetes mellitus was produced by a single intraperitoneal injection of STZ (55mg/kg b.w.

Easy preparation of enantiomerically enriched heteroaromatic alcohols through lipase-catalyzed acylation with succinic anhydride under unconventional activation.

This study reports the lipase-catalyzed resolution of heteroaromatic secondary alcohols by succinic anhydride under different activation conditions by convenient procedure with succinic anhydride. The effects of succinic anhydride and the nature of the heteroatom are discussed in standard conditions in the kinetic resolution with lipases. The results recorded under microwave activation and ultrasonication is compared.

Sonochemical degradation of naphthol blue black in water: Effect of operating parameters.

In this work, the sonochemical degradation of naphthol blue black (NBB), an acidic diazo dye, in water was investigated. The effects of several operating parameters such as initial NBB concentration, acoustic intensity, ultrasonic frequency, nature of the dissolved gas and solution pH on the degradation of the dye were carried out. The obtained results showed that ultrasound completely destroyed NBB (5 mg L(-1)) after 45 min of sonication and most of the chemical oxygen demand was eliminated after 90 min of treatment.

Asymmetric reduction of ketones by biocatalysis using clementine mandarin (Citrus reticulata) fruit grown in Annaba or by ruthenium catalysis for access to both enantiomers.

Biocatalytic reduction of prochiral ketones using freshly ripened clementine mandarin (Citrus reticulata) in aqueous medium is reported. High enantioselectivities were observed, especially for the bioreduction of indanone , tetralone , and thiochromanone with respectively 95%, 99%, and 86% enantiomeric excess (ee). Enantioselective bio- and metal-catalyzed reactions were compared.