Ultrasonic Bath Research Articles

BaTiO3 Catalyzed Ultrasonic Driven Piezoelectric Induced Reversible Addition-Fragmentation Chain-Transfer Polymerization in Aqueous Media.

Compared with normal stimulus such as light and heat, ultrasonic possesses much deeper penetration into tissues and organs and has lower scattering in heterogeneous systems as a noninvasive stimulus. Reversible addition-fragmentation chain-transfer polymerization (RAFT) in aqueous media w a s performed in a commercial ultrasonic wash bath with 40kHz frequency ultrasonic, in the presence of piezoelectric tetragonal BaTiO3 (BTO) nanoparticles. Owing to the electron transfer from BTO under the ultrasonic action, the water could be decomposed to produce hydroxyl radical (HO•) and initiated the RAFT polymerization (Piezo-RAFT). The Piezo-RAFT polymerization exhibited features of controllable and livingness, such as linear increase of molar mass and narrow molar mass distributions (Mw/Mn<1.20). Excellent temporal control of the polymerization and the chain fidelity of polymers w e r e illustrated by "ON and OFF" experiment and chain extension, separately. Moreover, this ultrasonic driven piezoelectric induced RAFT polymerization in aqueous media can be directly used for the preparation of piezoelectric hydrogel which have potential application for stress sensor. This article is protected by copyright. All rights reserved.

Extraction of Antioxidants from Brown Macroalgae Fucus spiralis

In this study, different extraction methods and conditions were used for the extraction of antioxidants from brown macroalgae Fucus spiralis. The extraction methodologies used were ultrasound-assisted extraction (ultrasonic bath and ultrasonic probe), extraction with a vortex, extraction with an Ultra-Turrax® homogenizer, and high-pressure-assisted extraction. The extracts were analyzed for their total phenolic content (TPC) and their antioxidant activity, and evaluated through the 2,2-difenil-1-picrilhidrazil (DPPH) free radical scavenging method and ferric reducing antioxidant power (FRAP) assay. Ultrasonic probe-assisted extraction yielded the highest values of TPC (94.78–474.16 mg gallic acid equivalents/g extract). Regarding the antioxidant activity, vortex-assisted extraction gave the best DPPH results (IC50 1.89–16 µg/mL), while the highest FRAP results were obtained using the Ultra-Turrax® homogenizer (502.16–1188.81 μmol ascorbic acid equivalents/g extract). For each extraction method, response surface methodology was used to analyze the influence of the experimental conditions “extraction time” (t), “biomass/solvent ratio” (R), “solvent” (S, water % in water/ethanol mixture), and “pressure” (P) on TPC, DPPH, and FRAP of the F. spiralis extracts. In general, higher TPC content and higher antioxidant capacity (lower IC50 and higher FRAP) were obtained with higher R, t, and P, and lower S (higher ethanol %). The model regarding the combined effects of independent variables t, R, and S on the FRAP response values for vortex-assisted extractions best fitted the experimental data (R2 0.957), with optimal extraction conditions of t = 300 s, R = 50 g, and S = 25%.

Niosome gels encapsulate green mangosteen peel extract (Garcinia mangostana L.) as an anti-acne-inducing bacterial and anti-inflammatory activity

This research aims to develop a niosome gel from green mangosteen peel extract (Garcinia mangostana L.) by maceration with an ethanol solvent. The result of the yield percentage was 14.35 ± 0.90. The result of analyzing the phytochemicals by high-performance liquid chromatography (HPLC) was that tannin and xanthone were equal to 0.7483 ± 0.0825 mg per 100 mg of extract and 0.02964 ± 0.0088 mg per 100 mg of extract, respectively. The results of the determination of the effect include anti-inflammatory and anti-bacterial (Cutibacterium acnes) as anti-inflammatory with nitric oxide from LPS-induced macrophage cells up to a maximum equal to 29.10 ± 4.78% as a concentration at 1 mg mL–1 as acetonide can inhibit nitric oxide equal to 33.12 ± 3.62% as a concentration at 1 mg mL–1. and anti-bacterial (Cutibacterium acnes) by broth microdilution and drop plate methods, it was found that clindamycin has a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 0.08 μg mL–1 and 0.31 μg mL–1, respectively. The development of niosomes consisting of cholesterol, tween 60, and mangosteen peel extract at 1% w w–1 and 2% w w–1 in every formula showed good stability. The reduction of particle size in the formula by an ultrasonic bath at 30 minutes and measurement of particle size with a transmission electron microscope (TEM) were found to be equal to 1,265 and 123 – 219 nm, respectively. The polydispersity index (PDI) was in the range of 0.1 – 0.2, and the zeta potential value was in the range of –26.15 to –28.61 mV. The result of hydration and trans epidermal water loss (TEWL) was found to be that after 4 weeks of use, the formula containing the niosomes of mangosteen peel extract concentrated at 2% w w–1 maximizes skin moisture. It has a value of 346 ± 39.27 and has the least surface water loss. GRAPHICAL ABSTRACT HIGHLIGHTS The green mangosteen peel extract (Garcinia mangostana L.) can inhibiting nitric oxide production from LPS-induced macrophage cells up to 29.10  ± 4.78% at a concentration of 1 mg ml-1, the lowest inhibitory (MIC)  and kill (MBC) concentration of C. acnes bacteria less than 0.24 mg ml-1. The particle size of niosomes encapsulate extracts before reducing particle size equal to 1,265 nm. and after reducing particle size in the range of 123 - 219 nm. The skin hydration value after using product for 4 weeks as niosome gel encapsulate extract 2%w w-1 of extract was maximum moisture and minimal water loss.

New fabric phase sorptive extraction for nondestructive analysis of heritage textile samples

Several types of pesticides used in museum collections over time become dangerous for people who may handle textile articles treated with such substances. In the case of the analysis of ancient, modern, and contemporary textile materials, it is particularly important to keep the artifacts intact, as they cannot be replaced. The need to use micro- or nondestructive techniques led to the development of methods such as solid-phase microextraction (SPME), liquid‒liquid dispersive microextraction (DLLME), and single-droplet microextraction (SDME). In this paper is described an optimized extraction method of three pesticides (malathion, methoxychlor, and permethrin) by creating a non-destructive solid phase extraction system on a textile support, abbreviated FPSE – 100 % cotton fabric coated with a sol-gel solution prepared from a polymer (PEG or PDMS). To obtain a suitable FPSE, the following parameters were evaluated: polymer selection (individual or mixture of polymers), acid catalyst (trifluoroacetic acid, acetic acid and hydrochloride acid), amount of polymer (1.0 g, 2.5 g or 5.0 g), polymerization time (30 min, 120 min and 240 min), ultrasonic bath temperature (40 °C and 70 °C), and type of bath to obtain the sol-gel (ultrasonic bath, water bath with stirring and mechanical stirrer). To complete the FPSE optimization, the influence of pesticide extraction time on FPSE and desorption from FPSE in ethyl acetate was also assessed.The pesticides extraction yields obtained for the laboratory textile samples are in the range of 52.7 %–128.0 %. The technique proposed in the manuscript proved to be effective as a nondestructive tool for evaluating and quantifying the presence of pesticides in textile museum collections. The approach described here reduces heritage object damage due to sampling compared to methods commonly employed and may represent a starting point for future research.

Ultrasonic cavitation noise extraction based on fence sampling

The composition of the ultrasonic cavitation sound field is complex, including fundamental, harmonic, subharmonic, super-harmonic, and broadband transient noise. Fundamental waves, harmonics, etc., may interfere with the analysis and research of broadband transient cavitation noise, so it is necessary to filter out these interferences in the sound field. This article conducts measurement experiments on the ultrasonic cavitation sound field generated by high-power ultrasonic cleaning transducers. By utilizing the characteristics of the fence effect, the acoustic signal in the ultrasonic cavitation sound field is resampled through fence sampling so that the fundamental and harmonic components are fused at 0 Hz and filtered out. The ultrasonic cavitation noise is successfully extracted, and its signal structure is the same as the noise component structure in the original signal.

Formulation and Evaluation of Ketoconazole Nano-suspension

The use of antifungals that are widely used by the public is ketoconazole. Ketoconazole is included in the Biopharmaceutical Classification System (BCS) II category, where the drug is poorly soluble in water but has high permeability. In this study, ketoconazole was prepared in a nanosuspension formulato increase solubility. The method for preparing 2% ketoconazole nanosuspension used a sonicator bath with variations of tween 80 (F1 8%, F2 10%, F3 12%) and transcutol as surfactant and co-surfactant. The results showed that the particle size of the ketoconazole nanosuspension F1 was 102 ± 4.3 nm, F2 was 105 ± 3.2 nm, and F3 was 90 ± 2.4 nm on day 0. Testing on day 28 showed an increase in particle size in F1 115 ± 3.1 nm, F2 129±4.5nm, F3 97±2.4nm (p&gt;0.05). In testing the morphology of the nanosuspension using Scanning Electron Microscopy (SEM), The results showed that the irregular spheres were scattered. Organoleptic testing showed clear and homogeneous preparations. pH testing for 28 days showed a pH range of 5.6-6 which is included in the physiological skin pH range (p&gt;0.50). Nanosuspension preparations can be said to meet the physical evaluation requirements.

High Potential Electrochemical Synthesis of Thermally Reduced Graphene Nanomaterial

In this study, we provide electrochemical techniques for synthesizing thermally reduced graphene nanomaterial that have high potential, low defects, cost-effectiveness, and ecological sustainability. The electrochemical exfoliation is carried out by employing a 195 W DC (voltage = 60[Formula: see text]V and current = 3.25 A) power source at a maximum electrolyte temperature of about 92.5∘C within the aqueous suspension of 2[Formula: see text]M of sulfuric acid (H2SO[Formula: see text]. Thereafter, the synthesized nanomaterial was treated in the weak piranha [combination of sulfuric acid and hydrogen peroxide (H2O[Formula: see text]] solution using an electrochemical technique inside the water bath sonicator at 80∘C. X-ray diffraction (XRD) analysis shows the peak of diffraction to the (002) plane of the reduced graphene oxide (RGO) samples emerges at around 2[Formula: see text] and 26.56∘ with an interplanar distance of 3.40 Å and 3.54 Å. According to the XRD data, after the high-temperature thermal reduction phase, the structure of the crystals and interplanar separation were recovered. The size of the crystallite of RGO produced under H2SO4 conditions was discovered to be greater than the crystallite size of graphene oxide produced under piranha solution conditions. The Raman analysis results show that the degree of disorder of the graphene synthesized within the H2O2 was higher than in comparison to the graphene synthesized in H2SO4. Field emission scanning electron microscopy (FE-SEM) results show that graphene synthesized in the presence of H2O2 has a thin and porous microstructure in comparison to H2SO4 with no significant effect on the presence of the availability of the C/O ratio. The atomic force microscopy (AFM) analysis indicates that the surface roughness of the graphene synthesized in the H2O2 was higher than that of the H2SO4. The Fourier transform infrared spectroscopy (FT-IR spectroscopy) analytical results show that the majority of the functional groups have been eliminated within the samples.

Developing of an eco-friendly liquid-liquid microextraction method by using menthol-based hydrophobic deep eutectic solvent for determination of basic fuchsin dye: assessment of the greenness profile.

Herein, we aimed to develop a new environmentally friendly liquid-liquid microextraction (LLME) method based on hydrophobic deep eutectic solvent (hDES) synthesized using biodegradable dl-menthol and decanoic acid for the spectrophotometric determination of toxic basic fuchsin dye in environmental water samples. The parameters affecting the extraction efficiency such as pH, mole ratio, and volume of hDES (1:2) and type and volume of organic solvent, sample volume, times of vortex, ultrasonic bath and centrifuge, ionic strength, and matrix effect were investigated and optimized. Under optimal conditions, the calibration curve showed linearity in the range of 7.4-167μg L-1 with a coefficient of determination of 0.9994. The limit of detection, intra-day and inter-day precision, and recovery values were 2.25μg L-1, 2.46% and 4.45%, and 105 ± 3%, respectively. The preconcentration and enrichment factors were found to be 30 and 61.5, respectively. The proposed hDES-LLME methodology was successfully applied to the environmental water samples to detect toxic BF dye (95-105%). Finally, the ecological impact of the suggested method was evaluated using the analytical eco-scale (PPS:88), complementary green analytical procedure indexe (ComplexGAPI), and the Analytical GREEnness tool (0.63). The assessment results showed that the presented analytical method can be regarded as a green LLME approach for the determination of the BF in water.

Analysis of varietal advantages of leaf form &lt;i&gt;Apium graveolens&lt;/i&gt; L. according to chlorogenic acid content

Introduction. Special studies on the benefits of agricultural crops – current research regarding the prospects for the development of their products based on functional and specialized nutrition. Substances with a phenolic profile carry out various types of pharmacological activity aimed at treating metabolic and other socially significant phenomena, which allows them to be positioned as generally accepted main ingredients. The leafy botanical form of celery is a rich source of phenolic compounds.Aim. Development and validation of a method for the quantitative analysis of chlorogenic acid to assess the varietal advantages of Apium graveolens L. raw materials using HPLC.Materials and methods. For the analysis, we used leaf celery grass of different varieties grown at two sites (the village of Lembolovo and SNT "Ruchey"). Sample preparation of raw materials was carried out by extraction in an ultrasonic bath. Chromatography conditions: column Luna 5 μm C 18(100) Å LC Column 250 × 4.6 mm, thermostat temperature 40 °C, detection wavelength 327 nm. PF A 0.05 % TFA, PF B acetonitrile. Elution mode: 0 min 12 % B, 20 min 30 % PF B, 23 min 12 % PF B.Results and discussion. According to the data obtained, the accumulation of chlorogenic acid in celery raw materials depends on both the plant variety and the cultivation conditions. However, the difference in the quantitative content of the target component correlates between varieties grown on different sites. The highest content of chlorogenic acid was noted in the variety Nezhny (SNT "Ruchey") and amounted to 0.464 ± 0.012. The variety Summer Boom can be distinguished as the best variety.Conclusion. The results of the study can be used in the development and quality control of functional and specialized nutrition based on the leafy botanical form of odorous celery due to the high content of phenolic substances.

Comparative studies on enhancing pea protein extraction recovery rates and structural integrity using ultrasonic and hydrodynamic cavitation technologies

This study explored the efficacy of various cavitation technologies, including ultrasonic bath (USB), ultrasonic plate (US-plate), ultrasonic probe (US-probe), and hydrodynamic cavitation (HDC), in extracting proteins from peas. US-probe showed the highest protein recovery rate (52.53 g/hg protein in pea powder) among all lab-scale cavitation equipment while HDC demonstrated significant potential for scaling up, notably improving both the purity (80.35 g/hg dried precipitate) and recovery rate (56.85 g/hg) of pea protein isolate (PPI) compared to conventional extraction (CE). SDS-PAGE, LC-MS/MS, FTIR and Fluorescence analysis were used to analyse the impact of these cavitation technologies on the structures of pea protein. The results confirmed that cavitation preserved PPI's primary structure while altering its secondary and tertiary structures, particularly under US-probe treatment, which significantly unfolded proteins. The SEM results revealed a marked reduction in protein bodies adhering to starch granules in residues from US-probe and HDC treatments compared to CE, correlating with their higher protein recovery rates.

Tribological Performance of a Paraffinic Base Oil Additive with Coated and Uncoated SiO2 Nanoparticles.

Electric vehicles (EVs) have emerged as a technology that can replace internal combustion vehicles and reduce greenhouse gas emissions. Therefore, it is necessary to develop novel low-viscosity lubricants that can serve as potential transmission fluids for electric vehicles. Thus, this work analyzes the influence of both SiO2 and SiO2-SA (coated with stearic acid) nanomaterials on the tribological behavior of a paraffinic base oil with an ISO VG viscosity grade of 32 and a 133 viscosity index. A traditional two-step process through ultrasonic agitation was utilized to formulate eight nanolubricants of paraffinic oil + SiO2 and paraffinic base oil + SiO2-SA with nanopowder mass concentrations ranging from 0.15 wt% to 0.60 wt%. Visual control was utilized to investigate the stability of the nanolubricants. An experimental study of different properties (viscosity, viscosity index, density, friction coefficient, and wear) was performed. Friction analyses were carried out in pure sliding contacts at 393.15 K, and a 3D optical profilometer was used to quantify the wear. The friction results showed that, for the SiO2-SA nanolubricants, the friction coefficients were much lower than those obtained with the neat paraffinic base oil. The optimal nanoparticle mass concentration was 0.60 wt% SiO2-SA, with which the friction coefficient decreased by around 43%. Regarding wear, the greatest decreases in width, depth, and area were also found with the addition of 0.60 wt% SiO2-SA; thus, reductions of 21, 22, and 54% were obtained, respectively, compared with the neat paraffinic base oil.

Intensification of α-amylase activity using ultrasound and its application for food waste hydrolysis

The current research aims to study the ultrasound assisted intensification of activity of commonly applied amylase enzyme, under varying parameters like power, frequency, duty cycle, temperature and enzyme concentration. Two ultrasonic reactor configurations as bath and horn are used for comparing the efficacy of reactor configuration. The initial activity of native amylase was found as 5.77 U/g at optimum temperature of 35° C and pH 7. Under US bath treatment, α amylase attained maximum activity of 7.498 U/g at best treatment conditions of 120 W power, 30% duty cycle and 15 minutes of exposure time. In the case of US horn, application of 60 W power, 30% duty cycle, and 5 minutes of exposure increased the enzyme activity to 6.907 U/ g. Set of treatment approaches explored for obtaining highest yield of reducing sugars revealed the best approach of ultrasonic treatment of food waste followed by ultrasonic bath intensified amylase hydrolysis, yielding maximum amount of reducing sugars as 8.14 g/L in only 15 min. Overall the work elucidated the role of ultrasound in intensifying the enzyme activity as well as food waste hydrolysis maximizing the utilization of sustainable resource.

POLYCYCLIC AROMATIC HYDROCARBON IN SEDIMENT, GROUND AND SURFACE WATER RESOURCES IN COASTAL AREAS OF ONDO STATE, NIGERIA

Polycyclic aromatic hydrocarbons (PAHs) are of global concern due to their harmful effect on the health of human and the environment. They are known as persistent organic pollutants and linked to severe health effects in humans and ecosystem. This study aimed to investigate the presence and types of these hydrocarbons including assessing their distributions in groundwater water, surface water and sediment in Igbokoda, Irele and Okitipupa coastal areas of Ondo State, Nigeria. The watersamples were extracted with liquid-liquid extraction while the sediment samples were extracted with an ultrasonic bath extractor. The extracts were cleaned with alumina as adsorbent and analyzed using a gas chromatograph coupled to a mass spectrometer. The results showed wide variations in the concentrations of the analytes of interest in the different matrices studied. The total mean concentration range of these pollutants in the samples from the well, borehole, surface water, and the sediment were: 0.15 ± 0.31, 0.11±0.52 to 0.90± 0.28, 0.05±0.02 to0.11±0.52 and 0.16±0.14 to0.21±0.17, respectively. The result revealed that the concentrations of most of these contaminants were higher than the maximum permissible limit of PAH in drinking water and sediment. The contamination level was higher in the borehole water source than the others. The study concluded that all the investigated matrices were contaminated with these pollutants. The study recommended the enactment of new laws of regulating activities leading to the emissions of these pollutants by the Nigerian government inorder to safeguard the environment and human health.

Toxicity study and ameliorative effects of the aqueous leaf extract of Lecanoidiscus cupanioides Planch (ex. Benth) on the stress-induced ulcer

Lecaniodiscus cupanioides Planch (ex. Benth) is effective in treating burns, fevers, and inflammatory conditions. This study investigates the toxicity effects of the aqueous leaf extract (ALE) of L. cupanioides and its effect on stress-induced ulcers in animal models. The plant was collected and a 1:30 (g/ml) plant powder/solvent ratio was extracted using an ultrasonic bath at 50 °C for 45 min. Up-and-down procedure was used for acute toxicity. During subacute toxicity testing, a total of 20 mice were divided into four groups of five animals each. While group 1 served as control, groups 2, 3, and 4 received 250, 500, and 1000 mg/kg of the extract daily for 21 days. On day 22nd, animals were sacrificed and samples were collected for hematology, biochemical, and histological analyses. In the stress-induced ulcer activity, male albino mice were randomly separated into 5 groups of 5 animals, treated with the test drug, and then dissected after being stressed using the water immersion model. LD50 was &gt; 5000 mg/kg, and in biochemical examination, there was a significant decrease in the ALP level at medium and high doses (p value &lt; 0.05) and non-significant alterations in the values of urea, creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), body weight and hematology parameters (p &gt; 0.05). The histology results showed no evidence of liver and kidney toxicity. In conclusion, aqueous leaf extract of L. cupanioides was safe following a single dose (at 5000 mg/kg) and following repeated doses for 21 days (at 250, 500, and 1000 mg/kg). This study demonstrated that the extract had a significant effect on stress-induced ulcers at various dose levels when compared to the control (native, negative control, and omeprazole). The animals treated with 200mg/kg and 400mg/kg of the extract showed a significant increase in ulcer score, ulcer index, ulcer severity, and total acidity (p &lt; 0.05). The ulcer protection ability of the aqueous plant extract was dose-dependent.

Ultrasonic-Assisted Preparation of Biodiesel Products from Vegetable Oils.

Utilizing vegetable oil as a sustainable feedstock, this study presents an innovative approach to ultrasonic-assisted transesterification for biodiesel synthesis. This alkaline-catalyzed procedure harnesses ultrasound as a potent energy input, facilitating the rapid conversion of extra virgin olive oil into biodiesel. In this demonstration, the reaction is run in an ultrasonic bath under ambient conditions for 15 min, requiring a 1:6 molar ratio of extra virgin olive oil to methanol and a minimum amount of KOH as the catalyst. The physiochemical properties of biodiesel are also reported. Emphasizing the remarkable advantages of ultrasonic-assisted transesterification, this method demonstrates notable reductions in reaction and separation times, achieving near-perfect purity (~100%), high yields, and negligible waste generation. Importantly, these benefits are achieved within a framework that prioritizes safety and environmental sustainability. These compelling findings underscore the effectiveness of this approach in converting vegetable oil into biodiesel, positioning it as a viable option for both research and practical applications.

Effect of Post-Extraction Ultrasonication on Compositional Features and Antioxidant Activities of Enzymatic/Alkaline Extracts of Palmaria palmata.

Palmaria palmata is a viable source of nutrients with bioactive properties. The present study determined the potential role of post-extraction ultrasonication on some compositional features and antioxidant properties of enzymatic/alkaline extracts of P. palmata (EAEP). No significant difference was detected in terms of protein content and recovery, as well as the amino acid composition of the extracts. The nitrogen-to-protein conversion factor of 5 was found to be too high for the seaweed and EAEP. The extracts sonicated by bath for 10 min and not sonicated showed the highest and lowest total phenolic contents (p < 0.05), respectively. The highest radical scavenging and lowest metal-chelating activities were observed for the non-sonicated sample, as evidenced by IC50 values. The extract sonicated by bath for 10 min showed the most favorable in vitro antioxidant properties since its radical scavenging was not significantly different from that of the not-sonicated sample (p > 0.05). In contrast, its metal-chelating activity was significantly higher (p < 0.05). To conclude, post-extraction ultrasonication by an ultrasonic bath for 10 min is recommended to increase phenolic content and improve the antioxidant properties of EAEP.

Aqueous Theta-Phase Aluminum Oxide Nanofluid for Energy Applications: Experimental Study on Thermal Conductivity

The use of nanofluids in energy systems allows for increasing efficiency and developing more economic systems. Alumina-water is one of the most common nanofluids used but little information is available about the aqueous theta-phase aluminum oxide. Given the lack of thermal conductivity data for this nanofluid, in this research, this property is experimentally evaluated. Nanofluid is prepared using the two-step method, employing a magnetic stirrer and a sonication bath. A high-precision sensor is employed for measuring thermal conductivity, using the method of transient hot wire. The thermal conductivity measurements for the base fluid (water) are compared with data provided by NIST. Nanoparticle mass fraction in the nanofluid is increased from 1 to 10% and the temperature from 22.1 to 59.3 °C. Three sonication times (1.5, 4 and 16.5 h) are used. A strong dependence between the thermal conductivity and the temperature and nanoparticles concentration has been found, while the sonication time has a negligible influence on the thermal conductivity in the range of times tested. A correlation to obtain the thermal conductivity of the water-based nanofluid using theta-phase aluminum oxide has been developed, including nanoparticle volume concentration and temperature. An excellent agreement is obtained between predicted and experimental data.

The role of multi-walled carbon nanotubes in enhancing the hydrolysis and thermal stability of PLA.

Polylactic acid (PLA) is a bioresorbable and biodegradable polymer extensively used in various biomedical and engineering applications. In this study, we investigated the mass loss and thermal properties of PLA-multi-walled carbon nanotube (MWCNT) composites under simulated physiological conditions. The composites were prepared by melting PLA with 0.1, 0.5, 1.0, and 5.0 wt% MWCNTs using an ultrasonic agitator, and FTIR analysis confirmed composite formation. Subsequently, the composites were subjected to hydrolysis under simulated physiological conditions (pH 7.4 and 37°C) for up to 60days. The results revealed that the mass loss of the composites decreased with increasing MWCNT content, suggesting that the presence of MWCNTs decelerated the hydrolysis process. On day 58, the mass loss of pure PLA was 12.5%, decreasing to 8.34% with 0.1% MWCNT, 5.94% with 0.5% MWCNT, 4.59% with 1% MWCNT, and 3.54% with 5.0% MWCNT. This study offers valuable insights into the behavior of PLA-MWCNT composites under physiologically simulated conditions, facilitating the development of new polymer composites with enhanced thermal stability and degradation resistance for biomedical applications.

Microwave-assisted transesterification of sour cherry kernel oil for biodiesel production: comparison with ultrasonic bath-, ultrasonic probe-, and ohmic-assisted transesterification methods

In this study, sour cherry kernel oil was converted to biodiesel by microwave-assisted transesterification. Evaluations were made of several variables, namely, reaction time (1, 2, 3, 4, and 5 min), microwave power (100, 200, 300, 400, and 500 W), methanol/oil mole ratio (3, 6, 9, 12, and 15), and catalyst (KOH) concentration (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The efficiency of fatty acid methyl esters increased in response to lengthier reaction times, greater microwave power, higher methanol/oil mole ratio, and higher catalyst concentrations up to the optimal level. The optimal reaction conditions for microwave-assisted transesterification were 300 W microwave power, 1.2% catalyst concentration, a methanol/oil mole ratio of 1:2, and a reaction time of 4 min. Microwave-assisted transesterification was more effective than ohmic-, magnetic stirrer-, ultrasonic probe-, and ultrasonic bath-assisted transesterification methods. In conclusion, microwave-assisted transesterification can be suggested as a fast, efficient, and economical method compared to other transesterification methods.

Highly Efficient and Reproducible Sonochemical Synthesis of ZnO Nanocrystals.

Sonochemical synthesis can be a facile, fast, efficient, versatile and economical way to prepare a large variety of conventional or novel nanostructured materials (metallic, magnetic, semiconducting, polymeric, etc.). In this work, zinc oxide nanocrystals were synthesized by irradiating and heating at 90 °C in a commercial ultrasonic bath a water solution of zinc nitrate hexahydrate and ammonia solution or hexamethylenetetramine as base catalysts. The evolution of the powder morphology and its crystalline structure were investigated at different times of ultrasonic irradiation (0-9 hours) and compared with those of samples obtained by only heating the solutions in a muffle furnace in order to enlighten the growth mechanism. It resulted that: i) the crystal morphology depends on the selected base, ii) for samples obtained by using ultrasounds, the homogeneity of the powders depends on the irradiation time, iii) by comparing all samples obtained at 7 hours of heating, the aspect ratio of the crystals is higher for those that also underwent to ultrasounds.