Ultrasound-assisted production of biodiesel using engineered methanol tolerant Proteus vulgaris lipase immobilized on functionalized polysulfone beads

In the present study, Proteus vulgaris lipase (PVL) was engineered using directed evolution to increase methanol tolerance so that it would be more tolerant and efficient for harsh conditions employed in biodiesel synthesis, which is limiting their industrial use. The influence of ultrasound under different experimental conditions on the biodiesel conversion yield using methanolysis of non-edible neem oil was also emphasized. A special attention was also paid to the immobilization of lipase on Polysulfone (PS) beads and comparative studies with industrially used Burkholderia cepacia lipase. The Engineered Proteus vulgaris lipase showed >80% activity after 3 h when incubated in 50% methanol with simultaneous sonication. The lipase retained improved longevity (~70% residual activity) over wild-type PVL over repeated use.     

Inactivation of harmful Anabaena flos-aquae by ultrasound irradiation: Cell disruption mechanism and enhanced coagulation

Harmful algal blooms pose a potential threat to the safety of drinking water sources. Ultrasound is an effective method for algae removal. However, this method can lead to the release of algal organic matter and the effects and toxic mechanisms of ultrasound on Anabaena are still poorly understood. The destruction mechanism of Anabaena flos-aquae cells under different ultrasonic conditions, the safety of intracellular organic matter (IOM) release to water and the enhanced coagulation efficiency of ultrasound were studied. Results showed that high-frequency ultrasound was effective in breaking down algae cells. After 10 min ultrasonication at 20 kHz, 5 min at 740 kHz and 1 min at 1120 kHz, the algae cells were inactivated and algae growth was halted. Ultrasound radiation can lead to the release of IOM, primarily chlorophyll a and phycocyanin, followed by some tryptophan and humic substances, polysaccharides, and proteins. The sonicated ribosomes were considerably reduced, and the antioxidant system of cells was also damaged to some extent. The coagulation effect of algae cells was substantially improved after ultrasonication. Thus, the safety of algae cell removal could be improved by controlling the changes in physiological structure and IOM release of algae cells by adjusting the ultrasound parameters.     

Thiamine hydrochloride(VB1):An efficient catalyst for one-pot synthesis of α-aminophosphonates under ultrasonic irradiation

An efficient synthesis of novelα-aminophosphonates by the reaction of aldehydes and amines with triethyl phosphite in the presence of the easily available,inexpensive,and nontoxic catalyst thiamine hydrochloride(VB1).This method affords theα-aminopho-sphonates under the influence of ultrasound irradiation in aqueous medium,in short reaction times(4-6 min),high yields(85-95%), with improved purity.The process is green,mild,inexpensive and excellent yields are the main compensation of this procedure.     

Ultrasonic emulsification of eucalyptus oil nanoemulsion: Antibacterial activity against Staphylococcus aureus and wound healing activity in Wistar rats

The plant derived essential oil nanoemulsion was prepared using a mixture of components containing eucalyptus oil as organic phase, water as continuous phase, and non ionic surfactant, Tween 80, as emulsifier at a particular proportion of 1:1 v/v%. The ultrasonication was applied for varied processing time from 0 to 30 min to study the effect of time on the formation of nanoemulsion and physical stability of formulation by this method. The transparency and stability of emulsion was enhanced when the sonication time was increased compared to hand blender emulsion. The most stable nanoemulsion was obtained in 30 min sonication having the mean droplet diameter of 3.8 nm. The antibacterial studies of nanoemulsion against Staphylococcus aureus by time kill analysis showed complete loss of viability within 15 min of interaction. Observations from scanning electron microscopy of treated bacterial cells confirmed the membrane damage compared to control bacteria. Furthermore, the wound healing potential and skin irritation activity of the formulated nanoemulsion in Wistar rats, suggested non-irritant and higher wound contraction rate with respect to control and neomycin treated rats. These results proposed that the formulated system could be favourable for topical application in pharmaceutical industries.     

Ultrasound-promoted greener approach to synthesize α-hydroxy phosphonates catalyzed by potassium dihydrogen phosphate under solvent-free condition

We report a new environmentally-benign, convenient, and facile methodology for the synthesis of α-hydroxyphosphonates from an aromatic/heteroaromatic aldehyde with triethyl phosphite in the presence of potassium dihydrogen phosphate (KH₂PO₄) under ultrasound-assisted solvent-free conditions. Furthermore, a series of compounds were synthesized and characterized by melting point, EI-MS, NMR, and IR tools. Utilization of easy reaction conditions, isolation, and purification makes this manipulation very interesting from an economic perspective.     

An efficient ultrasound-promoted method for the synthesis of bis(indole) derivatives

In this paper, the reaction of indole with electron-deficient alkenes in aqueous media is reported. This procedure allows the synthesis of bis(indole) derivatives in good to high yields at 90 °C under silent and ultrasound irradiation conditions. Short reaction times and high yields of desired products are the main advantages of the presented procedure. This reaction catalyzed by 12-tungstophosphoric acid is operationally simple and considers environmental aspects by avoiding toxic catalysts and solvents.     

Highly selective electrochemical fluorination of organic compounds in ionic liquids

Recent studies on electrochemical partial fluorination in ionic liquid fluoride salts are reviewed. At first, historical background and some problems of electrochemical fluorination in organic solvents are briefly mentioned. Solvent-free electrochemical fluorinations in ionic liquids are explained as follows. Ultrasonication was found to improve both the yield and current efficiency for electrochemical fluorination of α-phenylthioacetate, which is mainly attributable to marked mass transport promotion of the substrate and the suppression of anode passivation. Highly regioselective and efficient fluorination of cyclic ethers, lactones, and cyclic carbonate was achieved in Et₄NF·4HF and Et₃N·5HF. Selective fluorination of hardly oxidizable phthalide was realized using a combination of imidazolium and fluoride ionic liquids. The unique effect of imidazolium ionic liquids on electrochemical fluorodesulfurization of 3-phenylthiophthalide was explained. Reuse of ionic liquids for electrochemical fluorination is also possible.     

Azeotropic Distillation- and Ultrasound-Promoted Lipase-Catalyzed Reactions

Lipase from porcine pancreas was demonstrated to catalyze reactions under azeotropic and ultrasonic conditions. Reaction rates were significantly enhanced 3 to 60-fold by applying azeotropic distillation and 7 to 83-fold by applying ultrasonication. For both conditions, enantioselectivities were retained.     

Preparation of fenofibrate nanoparticles by combined stirred media milling and ultrasonication method

The production of fenofibrate nanoparticles combining stirred media milling and ultrasonication method was investigated in the current work. The fenofibrate drug sample was first wet milled in stirred media mill for different times and subsequently processed by ultrasonication. The effects of ultrasonication time, power on final product particle sizes were studied. The pre milling by stirred media milling was resulted into reduction of comminution resistance of material. Subsequent treatment by ultrasonication produced smaller particles than obtained by stirred media milling alone. The resulting nanoparticles were found to exhibit excellent stability as investigated by particle size, zeta potential, and multiple light scattering measurement techniques. Further, qualities of nanoparticles obtained by combined approach were characterized by TEM and XRD analysis.     

Liquid chromatography with diode array detection and multivariate curve resolution for the selective and sensitive quantification of estrogens in natural waters

Following the green analytical chemistry principles, an efficient strategy involving second-order data provided by liquid chromatography (LC) with diode array detection (DAD) was applied for the simultaneous determination of estriol, 17β-estradiol, 17α-ethinylestradiol and estrone in natural water samples. After a simple pre-concentration step, LC–DAD matrix data were rapidly obtained (in less than 5 min) with a chromatographic system operating isocratically. Applying a second-order calibration algorithm based on multivariate curve resolution with alternating least-squares (MCR-ALS), successful resolution was achieved in the presence of sample constituents that strongly coelute with the analytes. The flexibility of this multivariate model allowed the quantification of the four estrogens in tap, mineral, underground and river water samples. Limits of detection in the range between 3 and 13 ng L⁻¹, and relative prediction errors from 2 to 11% were achieved.