Conjoint application of ultrasonication and redox pair mediated free radical method enhances the functional and bioactive properties of camel whey-quercetin conjugates

Ultrasonication, redox-pair generated free radical method and their combination (Ultrasonication/redox-pair method) was used for production of camel whey-quercetin conjugates. FTIR and SDS-PAGE confirmed successful production of whey-quercetin conjugates using ultrasonication and ultrasonication/redox-pair method. FTIR suggested existence of covalent (appearance of new peak at 3399 cm⁻¹) and non-covalent linkages (shifting of peak at 3271 cm⁻¹, 1655 cm⁻¹ (amide I), 1534 cm⁻¹ and 1422 cm⁻¹ (Amide II)) in the whey-quercetin conjugates. Moreover, SDS-PAGE of conjugates produced by ultrasonication as well redox-pair method indicated shifting of protein bands slightly towards high molecular weight due to increase in the mass of proteins due to the binding of polyphenols. All conjugates showed improved techno-functional and bioactive properties in comparison to whey proteins. Conjugates produced through ultrasonication showed smaller particle size, improved solubility, emulsifying and foaming properties while conjugates produced through ultrasonication/redox-pair method depicted superior antioxidant properties in comparison to whey. Furthermore, conjugated samples showed higher inhibition of enzymatic markers involved in diabetes and obesity with highest potential recorded in conjugates produced using ultrasonication. Therefore, ultrasonication can be successfully used individually as well as in combination with redox-pair for production of whey-quercetin conjugates with enhanced bioactive and techno-functional properties.     

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by thiamine hydrochloride in water under ultrasound irradiation

An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using thiamine hydrochloride as a catalyst has been achieved. These ultrasound-assisted reactions proceed efficiently in water in the absence of organic solvent. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.     

Boric acid catalyzed convenient synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines in aqueous media

A one-pot three-component condensation of an aldehyde, malononitrile, and thiophenol has been achieved by conventional and ultrasound method. The reaction has been catalyzed by boric acid in aqueous medium. This protocol afforded corresponding 2-amino-3,5-dicarbonitrile-6-thio-pyridines in shorter reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents.     

Effects of ultrasound treatment on the morphological characteristics,structures and emulsifying properties of genipin cross-linked myofibrillar protein

Genipin is a natural crosslinker that improves the functional properties of proteins by modifying its structures. This study aimed to investigate the effects of sonication on the emulsifying properties of different genipin concentration-induced myofibrillar protein (MP) cross-linking. The structural characteristics, solubility, emulsifying properties, and rheological properties of genipin-induced MP crosslinking without sonication (Native), sonication before crosslinking (UMP), and sonication after crosslinking (MPU) treatments were determined, and the interaction between genipin and MP were estimated by molecular docking. The results demonstrated that hydrogen bond might be the main forces for genipin binding to the MP, and 0.5 μM/mg genipin was a desirable concentration for protein cross-linking to improve MP emulsion stability. Ultrasound treatment before and after crosslinking were better than Native treatment to improve the emulsifying stability index (ESI) of MP. Among the three treatment groups at the 0.5 μM/mg genipin treatment, the MPU treatment group showed the smallest size, most uniform protein particle distribution, and the highest ESI (59.89%). Additionally, the highest α-helix (41.96%) in the MPU + G5 group may be conducive to the formation of a stable and multilayer oil–water interface. Furthermore, the free groups, solubility, and protein exposure extent of the MPU groups were higher than those of UMP and Native groups. Therefore, this work suggests that the treatment of cross-linking followed by ultrasound (MPU) could be a desirable approach for improving the emulsifying stability of MP.     

An organocatalyzed facile and rapid access to α-hydroxy and α-amino phosphonates under conventional/ultrasound technique

In the present work, successful implementation of ultrasound irradiation for the rapid synthesis of α-hydroxy and α-amino phosphonates under solvent-free conditions is demonstrated. Use of a novel catalyst (i.e., camphor sulfonic acid) in combination with ultrasound technique is reported for the first time. Comparative study for the synthesis of α-hydroxy and α-amino phosphonates using conventional as well as ultrasonication method is discussed.     

Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge

The effect of ultrasonication and Fenton oxidation as physico-chemical pre-treatment processes on the change of rheology of wastewater sludge was investigated in this study. Pre-treated and raw sludges displayed non-Newtonian rheological behaviour with shear thinning as well as thixotropic properties for total solids ranging from 10 g/L to 40 g/L. The rheological models, namely, Bingham plastic, Casson law, NCA/CMA Casson, IPC Paste, and power law were also studied to characterize flow of raw and pre-treated sludges. Among all rheological models, the power law was more prominent in describing the rheology of the sludges. Pre-treatment processes resulted in a decrease in pseudoplasticity of sludge due to the decrease in consistency index K varying from 42.4 to 1188, 25.6 to 620.4 and 52.5 to 317.9; and increase in flow behaviour index n changing from 0.5 to 0.35, 0.62 to 0.55 and 0.63 to 0.58, for RS, UlS and FS, respectively at solids concentration 10–40 g/L. The correlation between improvement of biodegradability and dewaterability, decrease in viscosity, and change in particle size as a function of sludge pre-treatment process was also investigated. Fenton oxidation facilitated sludge filterability resulting in capillary suction time values which were approximately 50% of the raw sludges, whereas ultrasonication with high input energy deteriorated the filterability. Biodegradability was also enhanced by the pre-treatment processes and the maximum value was obtained (64%, 77% and 73% for raw, ultrasonicated and Fenton oxidized sludges, respectively) at total solids concentration of 25 g/L. Hence, pre-treatment of wastewater sludge modified the rheological properties so that: (1) the flowability of sludge was improved for transport through the treatment train (via pipes and pumps); (2) the dewaterability of wastewater sludge was enhanced for eventual disposal and; (3) the assimilation of nutrients by microorganisms for further value-addition was increased.     

Ultrasonics as a tool for development of pine-needle extract loaded bee wax edible packaging for value addition of Himalayan cheese

In the present study, Himalayan cheese, kradi was coated with beeswax loaded with pine needle extract (PNE) to increase its shelf life and nutraceutical potential. PNE was extracted via ultrasonication and incorporated into beeswax at concentrations, 2:1, 1:1, and 2:3 (grams of beeswax to mL of PNE). The dispersion of PNE in the coatings was carried out using an ultrasonic probe at a frequency of 20 kHz for 15 min and at power rating of 500 W. The coatings were characterised using scanning electron microscopy, light microscopy, dynamic light scattering (DLS), fourier transmission infrared spectroscopy. DLS revealed a hydrodynamic diameter and zeta potential of 12.11 ± 0.41 µm and −19.32 ± 0.61 mV for coating loaded with highest concentration of PNE. The bioactivities of the coating including antioxidant, antidiabetic and antibacterial assays revealed significantly higher values with the increase in PNE concentration. Shelf life and sensory evaluation study including microbiological and sensory analysis revealed inhibition of mould growth and good score of texture and appearance with the increase in concentration of PNE. The study provides a future perspective for application of beeswax loaded PNE coatings in cheese industry.     

Effects of ultrasound on Microcystis aeruginosa cell destruction and release of intracellular organic matter

Harmful algal blooms negatively impact ecosystems and threaten drinking water sources. One potential method to effectively counteract algal blooms is ultrasonication. However, ultrasonication can easily lead to the release of intracellular organic matter (IOM). The purpose of this study was to investigate the relationship between the destruction of algal cells and IOM release at different ultrasound frequencies. Microcystis aeruginosa cells were ultrasonicated at 20 kHz with an intensity of 0.038 W/mL, 740 kHz with an intensity of 0.113 W/mL, and 1120 kHz with an intensity of 0.108 W/mL. The IOM release was detected by fluorescence spectroscopy in addition to the more commonly used haemocytometry and optical density. After ultrasonication for 15 min, the removal rate of algal cells reached 10.5% at 20 kHz, 9.46% at 740 kHz, and 35.4% at 1120 kHz. The 20 kHz and 740 kHz ultrasound caused local damage to algal cells and then disrupted them, whereas the 1120 kHz ultrasound directly disrupted most algal cells. The extracellular organic matter (EOM), which was increased by ultrasonication, mainly consisted of protein-like compounds, chlorophyll, and a small amount of humic-like substances. Gas vacuoles had been destructed before the cells were broken, as indicated by the decrease of cell size and the wrinkles on the cell surface. Moreover, the removal of algae cells while upholding integrity is more conducive to the safety of the water environment.     

Effect of Ultrasonication on Optical Properties and Electronic States of Conjugated Polymer MEH-PPV

Poly[2-methoxy-5-（2＇-ethyl-hexyloxy）-1,4-phenylene vinylene]（MEH-PPV）solutions with different concen-trations were prepared in chloroform for different ultrasonication times.The ultraviolet absorption and photoluminescence（PL）spectra of the MEH-PPV solutions were measured,and the electronic states of the polymer chains under different experimental conditions were studied.The results showed that the effects of ultrasonication on the dilute and concentrated solutions were different.After ultrasonication,the intensity of the absorption peak at 280 nm significantly decreased,relative to the absorption peak at 500 nm for both dilute and concentrated solutions,indicating that the proportion of the two excited states in the polymer chains had changed.For dilute MEH-PPV solutions,the blue-shifted absorption（at about 500 nm）and PL spectra show that ultrasonication also led to polymer chain degradation and thus shortened the effective conjugation length.For concentrated solutions,however,the peak positions of the absorption spectra remained unchanged.In addition,the effects of the solution temperatures on the optical spectra for the MEH-PPV solutions were also discussed.     

Ultrasound assisted two-stage biodiesel synthesis from non-edible Schleichera triguga oil using heterogeneous catalyst: Kinetics and thermodynamic analysis

Present work deals with the ultrasound-assisted biodiesel production from low cost, substantial acid value kusum (Schleichera triguga) oil using a two-step method of esterification in presence of acid (H₂SO₄) catalyst followed by transesterification using a basic heterogeneous barium hydroxide (Ba(OH)₂) catalyst. The initial acid value of kusum oil was reduced from 21.65 to 0.84 mg of KOH/g of oil, by acid catalyzed esterification with 4:1 methanol to oil molar ratio, catalyst concentration 1% (v/v), ultrasonic irradiation time 20 min at 40 °C. Then, Ba(OH)₂ concentration of 3% (w/w), methanol to oil molar ratio of 9:1, ultrasonic irradiation time of 80 min, and temperature of 50 °C was found to be the optimum conditions for transesterification step and triglyceride conversion of 96.8% (wt) was achieved. This paper also examined the kinetics as well as the evaluation of thermodynamic parameters for both esterification and transesterification reactions. The lower value of activation energy and higher values of kinetic constants indicated a fast rate of reaction, which could be attributed to the physical effect of emulsification, in which the microturbulence generated due to radial motion of bubbles, creates an intimate mixing of the immiscible reactants causing the increase in the interfacial area, giving faster reaction kinetics. The positive values of Gibbs-free energy (ΔG), enthalpy (ΔH) and negative value of entropy (ΔS) revealed that both the esterification and transesterification were non-spontaneous, endothermic and endergonic reactions. Therefore, the present work has not only established the escalation obtained due to ultrasonication but also exemplified the two-step approach for synthesis of biodiesel from non-edible kusum oil based on the use of heterogeneous catalyst for the transesterification step.