Journal articles on the topic 'ULTRASONIC ASSISTED CMT'
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NOMURA, Mitsuyoshi, Yutaka MATSUSHIMA, Yongbo WU, Masakazu FUJIMOTO, and Zhou LIBO. "2207 Effects of Ultrasonic Vibration on Abrasive Pellet Working Life for Si Wafer using Ultrasonic Assisted Fixed Abrasive Chemical Mechanical Polishing(UF-CMP)." Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21 2015.8 (2015): _2207–1_—_2207–4_. http://dx.doi.org/10.1299/jsmelem.2015.8._2207-1_.
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Teyeb, Ahmed, João Silva, Jamil Kanfoud, Phil Carr, Tat-Hean Gan, and Wamadeva Balachandran. "Improvements in the Microstructure and Mechanical Properties of Aluminium Alloys Using Ultrasonic-Assisted Laser Welding." Metals 12, no. 6 (June 17, 2022): 1041. http://dx.doi.org/10.3390/met12061041.
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Welding high-strength aluminium alloys is generally a delicate operation due to the degradation of mechanical properties in the thermally affected zone (TAZ) and the presence of porosities in the molten metal. Furthermore, aluminium alloys contain compounds that solidify before the rest of the base alloy, therefore acting as stress concentration points that lead to the phenomenon of hot cracking. This paper investigates the process of applying ultrasonic vibrations to the molten pool aluminium alloy AA6082 to improve both its microstructure and mechanical properties. We analysed conventional and ultrasonic-assisted laser welding processes to assess the sonication effect in the ultrasonic band 20–40 kHz. Destructive and nondestructive tests were used to compare ultrasonically processed samples to baseline samples. We achieved a 26% increase in the tensile and weld yield strengths of laser welds in the aluminium plates via the power ultrasonic irradiation of the welds under optimum ultrasonic variable values during welding. It is estimated that the ultrasound intensity in the weld melt, using a maximum power of 160 W from a pair of 28 kHz transducers, was 35.5 W/cm2 as a spatial average and 142 W/cm2 at the antinodes. Cavitation activity was significant and sometimes a main contributor to the achieved improvements in weld quality.
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Ming, Ping Mei, Di Zhu, Yang Yang Hu, and Yong Bin Zeng. "Experimental Research on Microelectroforming with Ultrasonic Agitation." Key Engineering Materials 375-376 (March 2008): 253–57. http://dx.doi.org/10.4028/www.scientific.net/kem.375-376.253.
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High frequency acoustic agitation is known to improve mass transport in conventional electroplating and electroforming. To better understand the effect of ultrasonic agitation on microelectroforms with high height-to-width aspect recessed microstructure features, electroforming of Ni from a nickel sulfamate type electrolyte under the influence of high frequency ultrasound (33KHz) at different level of power intensity from 2W/cm2 to 16W/cm2 was investigated experimentally in this paper, and then optimum operating parameters were determined basing on surface topography. A number of microelectroforming experiments assisted with acoustic agitation were further carried out to demonstrate and revise the optimum process parameters and further some metal microdevices were produced. Experimental results showed that fewer drawbacks in the microelectroforms, such as nubbles, pits, blunt-edges, and collapses were observed in the microcomponents when sonication power 12W/cm2~14W/cm2 was drawn on. Microelectroforming with ultrasonic irradiation at appropriate power intensity was characterized by better surface morphology and better uniform filling behavior.
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Li, Zhe, Daoguo Yang, Weidong Hao, Song Wu, Yan Ye, Zhidan Chen, and Xiaoping Li. "Ultrasonic vibration-assisted micro-hole forming on skull." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 231, no. 14 (October 24, 2015): 2447–57. http://dx.doi.org/10.1177/0954405415611363.
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In minimally invasive neurosurgery, there is a gap between the need for a micro-burr hole to be opened on the skull to expose the enclosed brain for further operation and the proper technology available. Conventionally, a burr hole is generated by a drilling perforator, which usually causes damage to the vital soft tissue beneath skull. Besides, because of the extremely low mechanical strength of a micro-drilling bit, a micro-hole cannot be generated on the hard skull by the conventional drilling method. To bridge this gap, an ultrasonic vibration-assisted micro-burr hole forming technique has been developed in this study and its effectiveness has been proved through in vitro experiment on cat skull. With the assistance of ultrasonic vibration (29.7 kHz), a micro-hole has been successfully formed on skull with a 300 µm diameter conically tipped tool. Ultrasonic vibration of a large amplitude is found beneficial because the thrust force can be greatly reduced by increasing the vibration amplitude. Moreover, the micro-hole forming is free of cutting and chips. The ultrasonic vibration is found to have a hammering effect similar to shot peening, and a layer of dense tissue is formed around the hole and no chip is generated in the hole forming process. Besides, since the ultrasonic vibration tool can only fragment hard bone tissue without causing damage to the soft tissue beneath skull, a safe micro-hole forming technique can be enjoyed. Based on the findings from this study, a micro-burr hole perforator can be developed for the next-generation minimally invasive neurosurgery.
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Cruz-Garibaldi, Bianka Y., Alma D. Alarcon-Rojo, Mariana Huerta-Jimenez, Ivan A. Garcia-Galicia, and Luis M. Carrillo-Lopez. "Efficacy of Ultrasonic-Assisted Curing Is Dependent on Muscle Size and Ultrasonication System." Processes 8, no. 9 (August 20, 2020): 1015. http://dx.doi.org/10.3390/pr8091015.
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Ultrasound-assisted marinade is a promising technology for reducing the time of traditional immersion marination. This study evaluated the effect of the ultrasonic system (bath or probe, amplitude 50 or 100%) and muscle sample size (3 or 5 cm3) on physicochemical quality, yield (salt content, fresh weight, and relative fresh weight), and bacteria counts associated with pork. The results showed a significantly high salt (p < 0.0001) content in 3 cm3 (11.54%) and 5 cm3 (8.88%) samples after 24 h marination by immersion. The 3 cm3 cubes marinated in a 100% probe system for 20 min presented an amount of salt (9.55%) that was quite close to the controls. The 3 cm3 samples treated by immersion and in a 50% probe system gained more relative weight (in relation to the initial weight, 7.45 and 6.64%, respectively) after 7 d at 4 °C. Meanwhile the 5 cm3 cubes marinated by immersion gained 8.1%. The other treatments showed a weight loss after treatment. Although significant differences were found in the fresh weight and in water holding capacity (WHC) in the 3 and 5 cm3 meat samples, the relative fresh weight is a real measure of weight gain, more relevant for the industry. Thus, the samples with the highest salt transfer experienced a phenomenon of “dehydration”, retaining less water. The 3 and 5 cm3 cubes marinated by immersion presented orange color tones due to the long processing time, while the probe system produced redder and brighter tones. Ultrasound as a technology to assist in marinades is not efficient for bacteria control of mesophilic, psychrophilic, or coliform. However, a significant increase in lactic acid bacteria (LAB) counts may bring benefits for meat preservation during refrigerated storage.
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Hao, Changchun, Hongjin Qu, Shi Chen, Wenjing Han, and Runguang Sun. "Ultrasound-assisted Extraction of Polysaccharide from Radix Bupleuri using Response Surface Methodology and Antioxidant Research of the Polysaccharide." Natural Product Communications 13, no. 4 (April 2018): 1934578X1801300. http://dx.doi.org/10.1177/1934578x1801300420.
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This report used Response Surface Methodology (RSM) to analyze the conditions that extracting polysaccharide compound from Radix Bupleuri using ultrasonic wave. For determining the optimal extraction conditions, four independent variables, temperature (°C), ultrasonic intensity (UI, W/cm2), dilution rate (water-material ratio, mL/g) and time (min), were investigated using Box-Behnken design. In the results, the best condition after optimization was dilution rate of 35.0:1, UI of 24.5 W/cm2, temperature of 69.5°C and time of 14.6 min. Extraction efficiency was 7.67% and the purity reached 44.14%. It illustrates that the ultrasound-assisted extraction (UAE) was efficient and suitable for extracting polysaccharide from Radix Bupleuri. This paper also investigated the antioxidant activity of Radix Bupleuri polysaccharide (RBP) on superoxide anion radical, hydroxyl radical, and 2,2-diphenyl-1-picry-hydrazyl (DPPH), in vitro experiment. The result indicated that RBP could remarkably sweep away the hydroxyl radical, and had the capacity for clearing away superoxide radical and DPPH.
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Chen, Xiwen, Xiaoqian Li, Weihua Gui, and Luca Landi. "Simulation and Experiment of New Ultrasonic Vibration Network." Shock and Vibration 2020 (September 27, 2020): 1–12. http://dx.doi.org/10.1155/2020/4913286.
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A reasonable ultrasonic vibration network can improve the casting quality of aluminum alloy. Ultrasonic vibration network based on a honeycomb structure has been designed, referred to as a new vibration network. The new vibration network can solve the problems of nonuniform distribution of power ultrasonic wave, small working area and low volume of ultrasonic vibration network, low efficiency of the frequency spectrum and power spectrum, and poor quality of aluminum alloy casting. The number of vibration nodes can be determined based on the number of layers of the vibration source nodes. The edge length of regular hexagonal honeycomb cells can be determined based on the size of the casting ingot. The output power and resonant frequency of the ultrasonic vibration network can be adjusted in real time according to the status of aluminum alloy melt. A seven-node new ultrasonic network and a four-node ultrasonic network with a traditional structure were selected and used in the experiment and simulation of a 500 mm diameter 2219 aluminum alloy ingot. In comparison with the traditional four-node ultrasonic network, the effective volume and area, frequency spectrum efficiency, and comprehensive coverage probability of the seven-node new ultrasonic vibration network increased by 34.06%, 23.12%, 17.25%, and 0.308, respectively. The difference between the desired value and average efficiency of the power spectrum was 0.292 W/cm2, and the average grain size of aluminum alloy decreased by 34.98 microns. These results indicate that the efficiency of ultrasonic-vibration-assisted casting system and the quality of aluminum alloy casting can be improved using the new ultrasonic vibration network.
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Kida, Małgorzata, Sabina Ziembowicz, and Piotr Koszelnik. "The Use of an Ultrasonic Field in Support of Classical Methods of Oxidising Component Leached from Microplastics in Bottom Sediments." Materials 14, no. 11 (June 2, 2021): 3029. http://dx.doi.org/10.3390/ma14113029.
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The work detailed here examined the impact of selected unit methods and ultrasonic removal of the widespread plastic additive di(2-ethylhexyl) phthalate (DEHP) from the bottom sediments of a body of water. To this end, hydrogen peroxide and a classic or modified Fenton process were used, supplemented by an ultrasonic field. The latter had a vibration frequency of 20 kHz and an acoustic wave intensity of 3.97 W/cm2. The impact of process parameters such as reaction environment, reaction time, initial impurity content, aging of the impurity, influence of processes on the content of organic matter and dissolved organic carbon, and elution of selected components from the matrix were all analysed. It emerged that the most effective process by which to remove DEHP from a solid matrix involved a modified Fenton process assisted by an ultrasonic field. The highest average degradation efficiency achieved in this way was 70.74%, for C0 = 10 mg/kg d.w. and t = 60 min.
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Abedini, Reza, and Mahmoud Mousavi. "Effect of different parameters on sonochemical synthesized nanocrystalline TiO2 particles." Chemical Industry and Chemical Engineering Quarterly 18, no. 2 (2012): 171–78. http://dx.doi.org/10.2298/ciceq110826059a.
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An ultrasonic-assisted method to directly prepare nanocrystalline TiO2 has been used. TiO2 was synthesized by the hydrolysis of Tetraisopropyl titanate (TIPT) in the presence of de-ionized water and ethanol under high-intensity ultrasonic irradiation (24 KHz, 300 W/cm2) at different conditions. The effect of water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time on the particle size of TiO2 has been investigated by using design of experiment (DOE). The water content, water-to-TIPT ratio, water-to-ethanol ratio and sonication time were varied in the range 100-150 ml, 50-75 v/v, 20-30 v/v and 3-4 hr, respectively. Particle size of TiO2 was characterized using particle size analyzer. The results of DOE show that water content has the greatest effect on the particle size of TiO2.
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Silva, Liliana J. G., André M. P. T. Pereira, Angelina Pena, and Celeste M. Lino. "Citrinin in Foods and Supplements: A Review of Occurrence and Analytical Methodologies." Foods 10, no. 1 (December 23, 2020): 14. http://dx.doi.org/10.3390/foods10010014.
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Citrinin (CIT) deserves attention due to its known toxic effects in mammalian species and its widespread occurrence in food commodities, often along with ochratoxin A, another nephrotoxic mycotoxin. Human exposure, a key element in assessing risk related to food contaminants, depends upon mycotoxin contamination levels in food and on food consumption. Commercial supplements, commonly designated as red rice, usually used in daily diets in Asiatic countries due to their medicinal properties, may pose a health problem as a result of high CIT levels. In addition to the worldwide occurrence of CIT in foods and supplements, a wide range of several analytical and detection techniques with high sensitivity, used for evaluation of CIT, are reviewed and discussed in this manuscript. This review addresses the scientific literature regarding the presence of CIT in foods of either vegetable or animal origin, as well as in supplements. On what concerns analytical methodologies, sample extraction methods, such as shaking extraction and ultrasonic assisted extraction (UAE), clean-up methods, such as liquid-liquid extraction (LLE), solid phase extraction (SPE) and Quick, Easy, Cheap, Effective, Rugged and Safe (QuECHERS), and detection and quantification methods, such as thin layer chromatography (TLC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), biosensors, and ELISA, are also reviewed.
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Zulkifli, Nor Syazana Adilah, Noraiham Mohamad, ANIS AQILAH ABD GHANI, Siang Yee Chang, Jeefferie Abd Razak, Hairul Effendy Ab Maulod, Mohd Fadli Hassan, et al. "Graphene Nanoplatelets Modified Chemlok® Adhesive System for Natural Rubber – Aluminium Bonded Component in Engine Mount." International Journal of Automotive and Mechanical Engineering 19, no. 1 (April 5, 2022): 9530–42. http://dx.doi.org/10.15282/ijame.19.1.2022.16.0735.
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Generally, the engine mount is made from rubber and mild steel bonded with a Chemlok® adhesive system. It could be modified to provide sufficient bonding between natural rubber and aluminum. Therefore, this work aims to study a nano-manipulated adhesive system by modifying the existing Chemlok® adhesive system at different weight percentages of graphene nanoplatelets (GNPs) loading via two steps ultrasonic-assisted stirring process by ultrasonic bath and hot plate. The natural rubber (NR)-aluminum (Al) substrates were bonded using a hot press machine under the pressure of 100 kgf/cm2 for 20 minutes at 140 °C temperature. The samples were subjected to a 90-degree peel test based on ASTM D429 by the UTM machine, and the peel-fractured surfaces were evaluated both physically and under SEM. The adhesive strength increased with the increment of GNPs in the modified Chemlok® 205/220 system. The GNPs modified Chemlok® system achieved 30% improvement than the existing adhesive. The analyses proved the modification was successful. The modified system with GNPs dispersed at certain intercalation levels showed active functional groups, reinforcing effects, and thermal stability.
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Yin, Wei, Lei Shi, Dan Hua Zhao, and Xiu Lian Zhang. "Synthesis of Three-Dimensionally Interconnected Hierarchical Meso/Mesoporous Tb3+ Doped Titania with Enhanced Photocatalytic Activity." Applied Mechanics and Materials 275-277 (January 2013): 1755–61. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.1755.
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The precursor was prepared by cohydrolysis reactions of Ti(OC2H5)4and Tb(OC2H5)6around micelles of cetyltrimethylammonium bromide processed by ultrasonic before the cohydrolysis reactions. After calcined the precursor, Terbium doped anatase with a three-dimensionally interconnected hierarchical meso/mesoporous structure had been successfully prepared using an ultrasonic-assisted routine of sol-gel. The three-dimensionally interconnected hierarchical meso/mesoporous structure of the prepared material was proved by high resolution transmission electron microscopy and N2adsorption-desorption analysis. The material prepared displays a pore width distribution curve of single peak at 17.8 nm and displays a range from 6 nm to 42 nm, and possesses a BET area of 105 m2/g and a porosity of 0.65 cm3/g. The results of XPS analysis show that Ti exists in the Ti4+form and Ti-O-Tb/H and Ti-O-Ti bonds exist in the surface of the mesoporous material prepared. The terbium-doped sensitive material prepared possessing a three-dimensionally interconnected hierarchical meso/mesoporous structure is conducive mass-transferring and light-harvesting, and shows that a photocatalytic activity for phenol is about 4.9 times than that of commercial P25 titania under a very weak UV-Vis irradiation condition.
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Nguyen, Thanh Tam, Hung-Hsiang Chen, Thi Hien To, Yu-Chen Chang, Cheng-Kuo Tsai, Ku-Fan Chen, and Yung-Pin Tsai. "Development of Biochars Derived from Water Bamboo (Zizania latifolia) Shoot Husks Using Pyrolysis and Ultrasound-Assisted Pyrolysis for the Treatment of Reactive Black 5 (RB5) in Wastewater." Water 13, no. 12 (June 8, 2021): 1615. http://dx.doi.org/10.3390/w13121615.
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Adsorbent made by carbonization of biomass under oxygen-limited conditions has become a promising material for wastewater treatment owing to its cost-effective, simple, and eco-friendly processing method. Ultrasound is considered a green technique to modify carbon materials because it uses water as the solvent. In this study, a comparison of Reactive Black 5 (RB5) adsorption capacity between biochar (BC) generated by pyrolysis of water bamboo (Zizania latifolia) husks at 600 °C and ultrasound-assisted biochar (UBC) produced by pyrolysis at 600 °C assisted by ultrasonic irradiation was performed. UBC showed a greater reaction rate and reached about 80% removal efficiency after 4 h, while it took 24 h for BC to reach that level. Scanning electron microscope (SEM) images indicated that the UBC morphology surface was more porous, with the structure of the combination of denser mesopores enhancing physiochemical properties of UBC. By Brunauer, Emmett, and Teller (BET), the specific surface areas of adsorbent materials were analyzed, and the surface areas of BC and UBC were 56.296 m2/g and 141.213 m2/g, respectively. Moreover, the pore volume of UBC was 0.039 cm3/g, which was higher than that of BC at 0.013 cm3/g. The adsorption isotherms and kinetics revealed the better fits of reactions to Langmuir isotherm and pseudo-second-order kinetic model, indicating the inclination towards monolayer adsorption and chemisorption of RB5 on water bamboo husk-based UBC.
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Zheng, Yi, Jue Cui, An-Hui Chen, Zhi-Min Zong, and Xian-Yong Wei. "Optimization of Ultrasonic-Microwave Assisted Extraction and Hepatoprotective Activities of Polysaccharides from Trametes orientalis." Molecules 24, no. 1 (January 2, 2019): 147. http://dx.doi.org/10.3390/molecules24010147.
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Ultrasonic-microwave assisted extraction (UMAE) of Trametes orientalis polysaccharides was optimized by response surface methodology. Hepatoprotective effects of a purified T. orientalis polysaccharide (TOP-2) were evaluated by alcohol-induced liver injury model mice. The optimal UMAE parameters were indicated as below: ratio of water to raw material 28 mL/g, microwave power 114 W, extraction time 11 min. The polysaccharides yield was 7.52 ± 0.12%, which was well consistent with the predicted value of 7.54%. Pre-treatment with TOP-2 effectively increased the liver index and spleen index in alcohol-treated mice. The elevated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels of mice after alcohol exposure were inhibited by TOP-2 administration. The liver tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) levels have decreased significantly as a result of alcohol exposure, while pre-treatment with TOP-2 could mitigate these consequences. Furthermore, pre-treatment with TOP-2 could efficiently boost the superoxidase dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, and observably constrain the malondialdehyde (MDA) level. The findings suggest that TOP-2 might be useful for alleviating the alcohol-induced hepatotoxicity via its antioxidant and anti-inflammatory potential.
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Uju, Uju, Joko Santoso, Wahyu Ramadhan, and Muhammad Fakhri Abrory. "Extraction of native agar from Gracillaria sp with ultrasonic acceleration at low temperature." Jurnal Pengolahan Hasil Perikanan Indonesia 21, no. 3 (December 29, 2018): 414. http://dx.doi.org/10.17844/jphpi.v21i3.24711.
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<em>Gracilaria</em> sp. is a potential agar-producing seaweed. The agar is conventially extracted at high temperature (80-100°C) for 2-3 hours, requiring a lot of energy. Ultrasonication-assisted extraction method<br />removes the requirement of high temperatures and shortening the extraction time, thus reduces the energy cost during extraction process. This study was aimed to determine the effects of temperatures (50 and 60°C) and times (45 and 60 minutes) of ultrasonication on the yield and properties of theproduced agar. Energy efficiency was also calculated based on the ratio of energy required with the amount of agar produced. The ultrasonication significantly increased the yield and energy efficiency. The selected treatment was the extraction with temperature 60°C for 60 minutes producing agar with thee yield of 12.45%, viscosity of 35.8 cP, white degree of 50.96%, moisture content of 12.59%, ash content of 7.07%, sulfate content 3.67% and gel strength 108.03 g/cm2. Agar produced with the selected treatment was grouped as native agar with low gel strength. <br /><br />
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Agian, Vadi, Syafiq Hakimi Kamaruddin, and Norhidayah Suleiman. "Valorisation of bioactive compounds from Bentong ginger (Zingiber officinale Roscoe var. Bentong) using ultrasound-assisted extraction." International Food Research Journal 29, no. 3 (June 30, 2022): 619–30. http://dx.doi.org/10.47836/ifrj.29.3.14.
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The present work demonstrated the bioactive compound recovery from Bentong ginger (Zingiber officinale Roscoe var. Bentong) using ultrasound-assisted extraction (UAE) in terms of crude yield (CY), as well as total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing-antioxidant power (FRAP), which reflected the antioxidant properties. These response variables were evaluated as functions of the independent variables; temperature (30 - 60°C), time (10 - 30 min), and ultrasonic intensity (1768 - 5304.10 W/cm2), using response surface methodology (RSM). The variables were optimised using quadratic polynomial through the correlations calculated from the regression models fitted to the experimental data. The predicted values of CY, TPC, FRAP, and DPPH under the optimal conditions (40°C, 3536.78 W/cm2, and 25 min) were 23.42%, 778.08 mg GAE/g, 636.08 µmol Fe2+/g, and 150.01%, respectively. These experimental values were well fitted with the predicted values, except for DPPH. With UAE set at the optimal conditions, a pre-leaching step (PLS) was added to the process to investigate its effect on the extraction. It was found that PLS-UAE produced higher extraction yields (30.15%); however, the antioxidant activity of the extracts was significantly (p < 0.05) higher at the optimised condition for UAE only treatment. The PLS application led to structural cell damage which increased CY, and this was validated through scanning electron microscopy (SEM).
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Zheng, Qinhua, Weijian Tan, Xiaolin Feng, Kexin Feng, Wenting Zhong, Caiyu Liao, Yuntong Liu, Shangjian Li, and Wenzhong Hu. "Protective Effect of Flavonoids from Mulberry Leaf on AAPH-Induced Oxidative Damage in Sheep Erythrocytes." Molecules 27, no. 21 (November 7, 2022): 7625. http://dx.doi.org/10.3390/molecules27217625.
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To evaluate the antioxidant activity of flavonoids extracted from Chinese herb mulberry leaves (ML), flavonoids from mulberry leaves (FML) were extracted and purified by using ultrasonic-assisted enzymatic extraction and D101 macroporous resin. Using LC-MS/MS-Liquid Chromatography with tandem mass spectrometry analysis, hesperidin, rutoside, hyperoside, cyanidin-3-o-glucoside, myricitrin, cyanidin, and quercetin were identified, and NMR and UV were consistent with the verification of IR flavonoid characteristics. The antioxidant activity of FML has also been evaluated as well as the protective effect on 2,2 0-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress. The results showed that FML exhibited powerful antioxidant activity. Moreover, FML showed dose-dependent protection against AAPH-induced sheep erythrocytes’ oxidative hemolysis. In the enzymatic antioxidant system, pretreatment with high FML maintained the balance of SOD, CAT, and GSH-Px; in the non-enzymatic antioxidant system, the content of MDA can be effectively reduced after FML treatment. This study provides a research basis for the development of natural products from mulberry leaves.
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Wang, Shuo, Caifeng Xie, Shupei Wang, Fangxue Hang, Wen Li, Kai Li, Anthony Mann, Sarina Sarina, William Doherty, and Changrong Shi. "Facile ultrasonic-assisted one-step preparation of sugarcane bagasse carbon sorbent for bio-based odor removal cat litter formulation." Industrial Crops and Products 187 (November 2022): 115493. http://dx.doi.org/10.1016/j.indcrop.2022.115493.
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Mohd Zawawi, Norakmalah, Fazlena Hamzah, Harumi Veny, Miradatul Najwa Mohd Rodhi, and Mahanim Sarif. "Chemical and Electrochemical Properties of Bamboo Activated Carbon Activate Using Potassium Hydroxide Assisted by Microwave-Ultrasonic Irradiation." ASEAN Journal of Chemical Engineering 21, no. 2 (December 30, 2021): 211. http://dx.doi.org/10.22146/ajche.64617.
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This paper presents the utilization of bamboo residue from the chopstick industry as modified carbon (AC) for supercapacitor application. Bamboo activated carbon (BAC) was activated using Potassium hydroxide (KOH) and assisted with microwave ultrasonic (Mw-U) irradiation to enhance the properties of bamboo activated carbon (BAC). Different microwave (Mw) power intensities of 100 W, 300 W, and 500 W at 30 minutes of retention time have been applied on activation and the carbonization process was conducted at temperature 800°C. The BAC was analyzed for the morphology using a scanning electron microscope and proximate and ultimate analysis. Then BAC with the higher surface area was subjected to the electrochemical analysis to determine the electrochemical properties. The study indicated Mw-U irradiation improved the morphology of the BAC, eliminated the impurity of the sample, and gave higher carbon content of BAC. The findings show that lower Mw-U irradiation power provided a higher surface area of BAC. The surface area of 646.87 m2/g and total pore volume of 2.8x10-1 cm3/g was obtained with a power intensity of Mw-U activation at 100 W. While, electrochemical properties, the specific capacitance (Cs) of BAC was 77 Fg-1 at 25 mVs-1 in 1 mol/L KOH of electrolyte for cyclic voltammetry (CV) which indicates the ability of the prepared BAC to be used as an electrode in supercapacitor application. This study determined that Mw-U irradiation can improve the properties of the bamboo during chemical activation and formed BAC that consists of supercapacitor properties.
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SELVARANI, V., S. KIRUTHIKA, V. SUDHA, A. GAYATHRI, and B. MUTHUKUMARAN. "Enhancement Effect of Fe-Co-Ni/BC Nanoparticles for Membraneless Fuel Cells." Asian Journal of Chemistry 32, no. 9 (2020): 2173–79. http://dx.doi.org/10.14233/ajchem.2020.22728.
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Biocarbon (BC) supported iron–cobalt–nickel (Fe–Co–Ni/BC) nanoalloy catalysts were synthesized by ultrasonic-assisted chemical reduction method. The morphological and physico-chemical characteristics show that the 1:1:1 composition of Fe–Co–Ni/BC catalyst has the Fe face-centered cubic (fcc) solid-solution structure showing the incorporation of Co and Ni. The electrocatalytic execution of this iron-based nanoalloy catalyst and its interaction with biocarbon was explored in a membraneless fuel cell and compared with carbon supported Fe–Co–Ni catalyst (Fe–Co–Ni/C). In a single-cell test, the power density obtained for Fe–Co–Ni/BC (35.4 mW/cm2) was better than that of Fe–Co–Ni/C (31.3 mW/cm2), utilizing 0.1 mol/L sodium perborate as oxidant and 1 mol/L ethylene glycol as fuel in an alkaline medium. The electrochemical findings revealed that the execution and solidness of the Fe–Co–Ni/BC catalyst is good and prevalent to that of Fe–Co–Ni/C catalyst. The better execution of BC-supported catalyst is due to its high electrical conductivity, high porosity and expansive surface area. It is been concluded that both the advantageous impact and the nature of support have an imperative part on the execution of Fe–Co–Ni/BC nanoalloy catalysts for the CO2-free ethylene glycol oxidation. Subsequently, it is accepted that the BC-supported Fe–Co–Ni nanoalloy catalysts are anticipated to be broadly utilized in electrocatalytic energy-conversion applications.
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Khan, Ibrahim. "Pluronic-123 Assisted Synthesis of Cobalt Vanadate Microparticles (µ-CoV MPs) for Durable Electrochemical Oxygen Evolution Reaction in Seawater and Connate Water." Catalysts 13, no. 3 (March 22, 2023): 636. http://dx.doi.org/10.3390/catal13030636.
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Exploring different catalytic material paradigms could drive the search for the best oxygen evolution reaction (OER) catalyst to achieve industrially-feasible hydrogen fuel from water. Cobalt-based materials are considered good choices in this regard. Herein, we synthesized Pluronic-123 (P-123)-stabilized, unique, rough, globular-shaped cobalt vanadate microparticles (µ-CoV MPs) using an ultrasonic-assisted solvothermal method. The as-synthesized µ-CoV MPs were subjected to high-temperature annealing to improve the crystallinity and the surface polymer moieties were pyrolyzed. Conventional SEM, XRD, FTIR, and BET analyses evaluated the morphological and structural features. The temperature-controlled crystalline phase led to extensive OER performance in SW electrolytes. The OER onset potential (VOER) was observed at 1.557 V@10 mA/cm2 in seawater (SW) for µ-CoV MPs annealed at 400 °C compared to the VOER of 1.632 V of non-annealed µ-CoV MPs. The current density showed a steep increase beyond 1.557 V, confirming the excellent electrokinetics OER behavior of the µ-CoV MPs-deposited electrode. The chronoamperometric (I–t) OER stability comparison in SW and connate water (CW) electrolytes indicated only a <20% initial current density decrease after 8 h in the case of the SW electrolyte. However, the CW electrolyte posed serious challenges to the electrode and activity was completely lost after <2 h. The electrolytic comparison indicated that SW is highly suitable for µ-CoV MPs electrodes.
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Gu, Fan, Liang Tao, Runling Chen, Jiao Zhang, Xingzhong Wu, Min Yang, Jun Sheng, and Yang Tian. "Ultrasonic-Cellulase Synergistic Extraction of Crude Polysaccharides from Moringa oleifera Leaves and Alleviation of Insulin Resistance in HepG2 Cells." International Journal of Molecular Sciences 23, no. 20 (October 17, 2022): 12405. http://dx.doi.org/10.3390/ijms232012405.
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Moringa oleifera leaves (MOL) are a new food resource, rich in functional factors. MOL polysaccharides are important active macromolecules within MOL. However, there are problems, such as low extraction rates and lack of evidence for functional activity. Therefore, in this experiment, single-factor experiments were carried out using MOL powder as the raw material, and the Plackett–Burman test was used to screen the significantly influential test factors. The extraction process of MOL polysaccharide was optimized by response surface methodology. The insulin resistance alleviating activity of MOLP polysaccharides was initially explored. The results showed that the extraction of Moringa oleifera leaves crude polysaccharides (MOLP) by ultrasonic assisted cellulase enzymatic digestion was (17.03 ± 1.03)%, and the obtained MOLP was a crude polysaccharide with an average molecular weight (Mw) of 279.48 kDa, consisting of fucose, rhamnose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid. MOLP had an IC50 value of 8.02 mg/mL for α-glucosidase and scavenging activity against free radicals such as ABTS, DPPH, hydroxyl radicals, and superoxide anion with an IC50 value of 0.21 mg/mL 0.31 mg/mL 0.97 mg/mL 0.49 mg/mL. At the same time, MOLP significantly enhanced the glucose consumption, glycogen synthesis, CAT, SOD, GSH-Px activity, and reduced the MDA and ROS content in high glucose-induced insulin-resistant HepG2 (IR-HepG2) cells. This experiment improved the extraction rate of MOLP and demonstrated that MOLP has antioxidant activity and α-glucosidase inhibitory activity, which can alleviate the insulin resistance of high glucose-induced HepG2 cells. It provides partial data support for the possible hypoglycemic effect of MOLP by alleviating oxidative stress, and also provides new ideas for the in-depth study of basic research and industrial application of MOLP.
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Sakooei-Vayghan, Roghieh, Seyed Hadi Peighambardoust, Javad Hesari, Maral Soltanzadeh, and Donatella Peressini. "Properties of Dried Apricots Pretreated by Ultrasound-Assisted Osmotic Dehydration and Application of Active Coatings." Food Technology and Biotechnology 58, no. 3 (August 8, 2020): 249–59. http://dx.doi.org/10.17113/ftb.58.03.20.6471.
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Research background. The worldwide demand for healthy and sulphur-free dried vegetables and fruits has grown. Combined ultrasound-assisted osmotic dehydration (UOD) and application of active coatings incorporating natural preservatives represents an attractive alternative for sulphuring process to preserve the sensorial and nutritional quality of dried fruits. The aim of this study was to investigate the effect of osmotic dehydration (OD) and UOD and the use of pectin coatings (alone or with citric acid, CA or ascorbic acid, AA) on physical, textural and microstructural properties of hot air-dried apricot. Experimental approach. Fresh apricot cubes (1 cm3) were pre-treated with either OD at a temperature of 55 °C for 30 and 45 min or UOD at two ultrasonic frequencies of 25 and 35 kHz for 30 and 45 min followed by application of active coatings with pectin alone, pectin + CA or pectin + AA for 10 min. All pre-treated coated samples were then hot-air dried at a temperature of 60 °C until a final moisture content of 20 % (wet basis) was reached. Physical (shrinkage, apparent and bulk densities), chemical (browning value, water activity), textural (firmness and shrinkage), microstructure and microbial load of dried apricot was studied. Results and conclusions. Application of OD and UOD improved physical and textural properties of the dried apricots. Moreover, apparent and bulk densities, rehydration capacity of OD and UOD pre-treated samples were increased. While, shrinkage, water activity and microbial load were decreased. Firmness of UOD pre-treated samples was significantly (p < 0.05) lower than that of OD ones. Likewise, increasing ultrasound frequency from 25 to 35 kHz led to a significant decrease in Fmax values of dried apricots. Furthermore, coating of the OD and UOD processed samples with pectin + CA increased Fmax and decreased rehydration capacity of dried apricots. Scanning electron microscopy of both OD and UOD samples illustrated improvement of textural properties. The utilization of both OD pre-treatment and pectin edible coatings resulted in a decrease in browning values. However, UOD increased browning values of the dried apricots. Coating of UOD samples with pectin + AA resulted in substantial discoloration in hot air-dried apricot. Novelty and scientific contribution. This study advances the knowledge in the field of fruit drying by combined application of OD or UOD pre-treatments with post-treatments with active edible coatings on different properties of hot-air dried apricot.
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Zaidi, Syed Imran M., Abdul Ahad Khan, Hemang B. Panchal, Zulfiqar Qutrio Baloch, Enambir Josan, and Timir K Paul. "Abstract 523: Ultrasound Assisted Thrombolysis Versus Catheter Directed Thrombolysis: A Meta-Analysis." Arteriosclerosis, Thrombosis, and Vascular Biology 37, suppl_1 (May 2017). http://dx.doi.org/10.1161/atvb.37.suppl_1.523.
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Introduction: Deep venous thrombosis (DVT) and pulmonary embolism (PE) have many methods of treatment including anti-coagulation, thrombectomy and thrombolysis. Thrombolysis can be achieved via systemic or local thrombolytic agents, with standard local thrombolysis achieved via catheter insertion in proximity to the thrombus and delivery of thrombolytic agents. Ultrasound-assisted catheter thrombolysis (UAT) is a relatively newer form of thrombolysis which utilizes ultrasonic energy, along with local thrombolytics to help in thrombus breakdown. The objective of our meta-analysis is to compare UAT and catheter directed thrombolysis (CDT) for treatment of DVT and PE. Methods: PubMed database was searched through January 2017. Three studies (n=156) comparing UAT (n=99) and CDT (n=57) for thrombolysis were included. End points were > 50% thrombus lysis, bleeding (moderate and severe), and mortality on short term follow up (<1 year). The relative risk (RR) or mean difference (MD) with 95% confidence interval (CI) was computed and p<0.05 was considered as a level of significance. Results: Thrombolysis success rate was similar with UAT and CDT (RR 1.06, CI 0.89-1.27, p=0.49). Moderate and severe bleeding events were similar with both groups (RR 0.71, CI 0.27-1.87, p=0.49). Mortality on short term follow up was significantly lower in UAT as compared to CDT (RR 0.47, CI 0.23-0.95, p=0.04). Conclusions: The results of our meta-analysis demonstrated no difference in thrombolysis success rate or bleeding events when using UAT Vs CDT, however short term mortality was significantly lower with UAT. Further controlled trials with larger sample sizes are required to assess the possible benefit of using ultrasonic energy for venous thrombolysis.
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Man Phan, Van, Chi Hai Tran, Thanh Hai Dam Thi, and Chi Trung Duong. "Effects of Ultrasound Assisted Extraction on Efficiency and Quality of Rice Bran Oil." Current Applied Science and Technology 23, no. 4 (December 29, 2022). http://dx.doi.org/10.55003/cast.2022.04.23.009.
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Effects of ultrasound-assisted extraction (UAE) conditions viz., ultrasound power and treatment time on extraction efficiency and quality of oil from rice bran were studied. The sonication power and irradiation time varied between 6.11, 12.23, and 18.35 W/cm2; and 5, 15, and 25 min, respectively. The recovery, physicochemical and phytochemical properties of UAE oil were measured and compared with conventional soxhlet extraction (SE) and pressurized liquid extraction methods (PLE). The results showed that increasing the ultrasonic irradiation time and power led to greater oil extractability. However, the oil quality and ultrasonic intensity were inversely correlated. Specifically, higher power intensity (18.35 W/cm2) and longer irradiation time (15-25 min) impaired the unsaturated fatty acids (UFAs) and phytochemical compositions of the extracted oil. The maximum oil extractability obtained by PLE and UAE (12.23 W/cm2 and 15 min) were 16.77 mg/g rice bran and 16.59 mg/g rice bran, respectively, and higher than the SE process (14.96 mg/g rice bran). No significant differences were shown among PLE and UAE (12.23 W/cm2 and 15 min) oils for the physiochemical and phytochemical properties. Similar to the PLE and SE oils, oleic acid was the dominant fatty acid in the UAEs oils, followed by linolenic and palmitic acids. Scanning electron microscopy (SEM) results showed that the UAE process effectively damaged the cell walls of rice bran, resulting in improved oil yield. Thus, UAE is a promising method for extracting oil from rice bran.
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Zhou, Mingchun, Guangsen Fan, Hanshuo Xia, Xiaohan Zhang, Chao Teng, and Xiuting Li. "Ultrasound-Assisted Production of Xylo-Oligosaccharides From Alkali-Solubilized Corncob Bran Using Penicillium janthinellum XAF01 Acidic Xylanase." Frontiers in Bioengineering and Biotechnology 9 (September 10, 2021). http://dx.doi.org/10.3389/fbioe.2021.755003.
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A novel treatment involving enzymatic hydrolysis using an acidic xylanase coupled with ultrasound was performed to improve the xylo-oligosaccharides (XOS) yield from corncob bran. The acidic xylanase (XynB) was purified to a most suitable pH, temperature, and operational parameters for ultrasound-assisted hydrolysis were determined. A preliminary mechanistic investigation was performed through circular dichroism (CD) spectroscopy, scanning electron microscope (SEM) and a laser particle size analyzer, and the effects of ultrasound on enzyme (XynB) and substrate (corncob bran) were assessed. The results show that the maximum XOS yield was 20.71% when the reaction pH and temperature were 4.3 and 50°C, the ultrasonic parameters were 50 kHz and 0.40 W/cm2, which was 2.55 fold higher than that obtained using a non-ultrasound-assisted enzymatic preparation. Mechanism studies indicated that ultrasonic pretreatment could reduce the β-fold content and increase the random coil content. Changes in structure and size of substrate were observed. The specific surface area of the XAC molecules is easy to carry out enzymatic reaction, which is beneficial to the production of XOS.
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Ituarte, Iñigo Flores, Mika Salmi, Suvi Papula, Juha Huuki, Björn Hemming, Eric Coatanea, Seppo Nurmi, and Iikka Virkkunen. "Surface Modification of Additively Manufactured 18% Nickel Maraging Steel by Ultrasonic Vibration-Assisted Ball Burnishing." Journal of Manufacturing Science and Engineering 142, no. 7 (May 14, 2020). http://dx.doi.org/10.1115/1.4046903.
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Abstract The scope of this research is to characterize and optimize the vibration-assisted ball burnishing of additively manufactured 18% Nickel Maraging steel for tooling applications. We evaluate the suitability of vibration-assisted ball burnishing as an alternative method to post-process additively manufactured tool steel. To do so, we assessed a single pass post-processing technique to enhance surface roughness, surface micro-hardness, and residual stress state. Results show that ultrasonic burnishing after age hardening functionalizes additively manufactured surfaces for tooling applications creating a beneficial compressive residual stress state on the surface. The surface micro-hardness (HV1) varied between 503 and 630 HV1, and the average surface roughness (Ra) varied between 1.31 and 0.14 µm, depending on process parameters with a maximum productivity rate of 41.66 cm2/min making it an alternative approach to functionalize additively manufactured tool components.
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Wu, Bowen, Xue Ding, Shaowei Li, Dongmei Huo, Fan Zhang, Weiyan Liang, Ling Li, and Zexia Dou. "Mechanical protective effect of lens anterior capsule disc on corneal endothelial cells during femtosecond laser-assisted cataract surgery in a rabbit model." BMC Ophthalmology 23, no. 1 (April 19, 2023). http://dx.doi.org/10.1186/s12886-023-02918-0.
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Abstract Purpose To evaluate the effects of a novel technique using an isolated lens anterior capsule disc (LACD) to protect corneal endothelial cells in rabbit eyes during femtosecond laser-assisted cataract surgery. Methods Experimental study. 40 rabbits were divided into endothelium-protected (experimental) and control groups, with 20 rabbits in each group. In the experimental group, after femtosecond laser capsulotomy, the isolated capsule disc was lifted to the corneal endothelium by an ophthalmic viscosurgical device. The endothelium was damaged for 1 min with an ultrasonic probe. The control group underwent the same surgery, except that the disc was removed immediately after capsulorhexis. Corneal endothelioscopy was performed preoperatively and on postoperative days (PODs) 3 and 7 to observe endothelial cell counts (ECC) and endothelial cell loss rate. Central corneal thickness (CCT) was measured before and at PODs 1, 3 and 7. Results There were 3.59%±1.88% (p < 0.001) and 2.92%±2.14% (p < 0.001) loss of ECC in experimental group at POD3 and POD7, respectively, while those in the control group were 11.62%±7.43% and 10.34%±5.77%, respectively. On POD 1, the difference in central corneal thickness was significant(P = 0.019) between the two groups. At POD 3 and POD 7, CCT was not significantly different (P = 0.597;0.913) between the two groups. Conclusions The isolated LACD technique significantly reduced damage to the endothelium caused by ultrasonic energy and protects corneal endothelial cells during phacoemulsification.
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Liu, Hui, Shuang Cui Li, Li Li Ma, Meng Xin, and xin wen. "High Energy Density PVDF-Based Composites with Efficient Stripping of Boron Nitride Nanosheets." ECS Journal of Solid State Science and Technology, April 14, 2023. http://dx.doi.org/10.1149/2162-8777/accd20.
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Abstract Bronnitride nanosheets (BNNS) have attracted considerable interest in preparing high energy density (Ue) polymer nanocomposites due to its intrinsic high breakdown strength and thermal conductivity. However, efficient fabrication of BNNSs remains a challenge due to the low yield and complex fabrication process, which limits their further wide applications in polymer-based dielectrics. In this study, effectively stripped thin layer BNNS were prepared with high yield by urea-assisted ball milling combined with ultrasonic thermal stripping. The results showed that BNNS not only achieved efficient stripping and good dispersion in liquid solutions, but also effectively increased the energy storage capacity of the PVDF-based composites, with the highest Ue (7.5 J/cm3 at 450 MV/m) achieved in 8wt% BNNS/PVDF composites.
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Sheng, Zunlai, Biying Wang, Jiahong Zhao, and Wenhui Yu. "Optimization of Ultrasonic-Assisted Extraction for Pinocembrin from Flos populi Using Response Surface Methodology." International Journal of Food Engineering 13, no. 5 (March 25, 2017). http://dx.doi.org/10.1515/ijfe-2016-0428.
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Abstract In this study, the ultrasound-assisted extraction (UAE) was used for extraction of pinocembrin from Flos populi. Based on the results of the single-factor experiment, four independent parameters, including ethanol concentration (40–80 %), extraction temperature (50–70 °C), extraction time (25–45 min) and electrical acoustic intensity (40.8–81.5 W/m2) were further investigated using response surface methodology (RSM) coupled with Box-Behnken design. The experimental data were fitted to the quadratic response surface model using multiple regression analysis with high adjusted determination coefficient value (R 2) of 0.9697. The highest yield (134.2 ± 1.53 mg/g) of pinocembrin was obtained under the optimal conditions (ethanol concentration of 68 %, extraction temperature of 69 °C, extraction time of 42 min and electrical acoustic intensity of 66.81 W/cm2), which agreed to the predicted value of 132.9 mg/g. Moreover, the comparison between the UAE and reflux extraction also showed the suitability of UAE for pinocembrin from Flos populi.
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Yuan, Shi-Jun, Wei-Yi Li, Tian-Tian Jian, and Yi Huang. "Anti-aging Activity of Xylaria striata in Drosophila melanogaster." South Asian Journal of Research in Microbiology, May 7, 2019, 1–7. http://dx.doi.org/10.9734/sajrm/2019/v3i330086.
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Aims: To evaluate the application potential of Xylaria striata Pat. in anti-aging field.
Methodology: Extracting the fruit body of X. striata by ultrasonic-assisted extraction method. In this study, Drosophila melanogaster was used as an anti-aging organism material. After feeding with different concentrations of extract, the natural survival time, survival time under oxidative stress and survival time under UV irradiation of D. melanogaster were all measured. In addition, the in vivo activity of SOD、CAT and MAD, protein concentration and body weight were determined to evaluate the anti-aging effect of ethanol extract from X. striata.
Results: The results showed that the ethanol extract of X. striata could extend the lifespan of D. melanogaster under both irradiation and oxidative stress condition. And the ethanol extract could enhance the activity of CAT in D. melanogaster, especially at concentration of 50 μM, and the content of MAD in D. melanogaster were decreased significantly.
Conclusion: This study clarified the anti-aging activity of X. striata in D. melanogaster and it would provide some theoretical basis for its further development and utilization in anti-aging drugs and health food.
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Aigueperse, Antoine, and Wilfrid Baroche. "Etat de l’art des architectures des cellules robotisées pour le contrôle par Ultrasons." e-journal of nondestructive testing 28, no. 9 (September 2023). http://dx.doi.org/10.58286/28469.
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Dans beaucoup d’applications industrielles, l’inspection des pièces en composite est réalisée par la méthode Through Transmission Ultrasonics (TTU) par jet d’eau. Généralement, ces méthodes sont déplacées avec des systèmes de mise en position simple (robot cartésien) ou complexe (cellule robotisée). Pour les petites pièces, des outillages spéciaux, pouvant être onéreux, sont conçus permettant de disposer les 2 transducteur de chaque côté de la pièce. Cette méthode n’est pas aisément transposable aux pièces de grandes dimensions ou à l’inspection en petite série. L’autre solution consiste à utiliser 2 robots disposés de part et d’autre de la pièce à inspecter. Les robots doivent être parfaitement synchronisés en position, ce qui complexifie énormément la programmation des robots. Cet article présente plusieurs cellules d’inspection – en réflexion ou transmission – robotisées composées d’un robot ou de 2 robots fonctionnant en mode Leader/Follower. Les architectures matérielles sont analysées et comparées. En seconde partie, une méthode de programmation pour cellule Leader/Follower est présentée à partir de l’application e-hub NDI. Ce logiciel de programmation hors ligne de robots industriels basée sur la CAO intègre des fonctions spécifiques à ce type de cellules telles que la modélisation des outils jet d’eau ou bien le couplage des robots en fonction de l’épaisseur de la pièce à contrôler. Il assiste l’opérateur de contrôle dans la création des programmes robots sans besoin d’expertise en robotique.
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HUO, LILI, Ravikiran Lingaparthi, Nethaji Dharmarasu, K. Radhakrishnan, and Casimir Chan. "Surface morphology evolution of N-polar GaN on SiC for HEMT heterostructures grown by plasma-assisted molecular beam epitaxy." Journal of Physics D: Applied Physics, April 18, 2023. http://dx.doi.org/10.1088/1361-6463/accde9.
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Abstract The surface morphology evolution of N-polar GaN with growth time was investigated and compared with Ga-polar GaN. N-polar GaN directly grown on SiC substrates was found to have slower three-dimensional (3D) to two-dimensional (2D) growth transformation and lesser coalescence than the Ga-polar counterpart, resulting in rougher surface morphology, whereas the AlN nucleation layer (NL) accelerated 3D to 2D transformation, resulting in smoother surface morphology. N-polar GaN was found to have mound-type surface morphology with clustered atomic steps, unlike the regular screw-type dislocation-mediated step-flow growth observed for Ga-polar GaN. This was explained by the lower diffusion of adatoms on the N-polar surface due to its higher surface energy and higher Ehrlich-Schwoebel barrier (ESB). In addition, the increased III/V ratio in N-polar GaN growth was found to reduce the surface roughness from 2.4 nm to 1 nm. Without Si doping, the N-polar GaN HEMT heterostructures grown under optimized conditions with smoother surface morphologies exhibited sheet carrier density of 0.91 × 1013 cm-2 and mobility of 1220 cm2/V∙s. With Si δ-doping, the sheet carrier density was increased to 1.28 × 1013 cm-2 while the mobility was reduced to 1030 cm2/V∙s. These results are comparable to the state-of-the-art data of PA-MBE-grown N-polar GaN HEMT heterostructures on SiC substrates.
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Holmes, Stuart Nicholas, J. Gough, Chong Chen, David A. Ritchie, and Michael Pepper. "Variable Range Hopping Conductivity in Molecular Beam Epitaxial InSb." Journal of Physics D: Applied Physics, September 22, 2022. http://dx.doi.org/10.1088/1361-6463/ac941c.
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Abstract A Variable Range Hopping-VRH transport mechanism can be induced in molecular beam epitaxial, n-type doped InSb wafers with focussed Ga+ ion beam damage. This technique allows areas of wafer to be selectively damaged and then subsequently processed into gated MISmetal-insulator-semiconductor devices where a disordered, two-dimensional device can be established. At high levels of damage (dose > 1016 Ga+ ions/cm2) amorphous crystalline behaviour results with activated conductivity characteristic of a three-dimensional system with VRH below 150 K. At lower doses (1014 to 1016 Ga+ ions/cm2) a thermally activated conductivity is induced at ~ 0.9 K, characteristic of Mott phonon-assisted VRH. At 1 K the devices either conduct with conductivity > ~ (e2/h) where e is the fundamental charge and h is Planck’s constant, or are thermally activated depending on the dose level. The lightly damaged devices show weak antilocalization signals with conductivity characteristic of a two-dimensional electronic system. As the Ga+ dose increases, the measured phase coherence length reduces from ~ 500 nm to ~ 100 nm. This provides a region of VRH transport where phase-coherent transport processes can be studied in the hopping regime with the dimensionality controlled by a gate voltage in an MIS-device.
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Hanifah, Umu, Juan Paolo Bermundo, Mutsunori Uenuma, and Yukiharu Uraoka. "Performance and Reliability improvement of All-solution Processed Indium Zinc Oxide Thin-Film Transistor by UV-irradiation treatment." Journal of Physics D: Applied Physics, June 16, 2023. http://dx.doi.org/10.1088/1361-6463/acdefb.
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Abstract Developing a low-temperature fabrication strategy for amorphous oxide semiconductors, such as amorphous Indium Zinc Oxide (IZO) channel layers, for use in flexible oxide-based thin film transistors (TFTs) is essential. In this work, high-performance and highly stable all-solution processed a-IZO TFTs were achieved by varying the duration of photo-assisted treatment (ultraviolet (UV) combination treatment), which combines UV irradiation with low heating temperature (115oC) by all-solution processed approach. From the experimental results, UV-irradiation can activate the IZO source, drain, and gate electrodes which induces TFT switching. X-ray Photoelectron Spectroscopy analysis revealed oxygen vacancy (Vo) generation after the UV combination treatment which increased the carrier concentration and improved the conductivity of IZO. All-solution processed a-IZO TFTs with high performance and stability was achieved at a low temperature of 115oC for 90 min treatment time, including high mobility (µ) up to 17.45 cm2/Vs, threshold voltage (Vth) = -1.2 V, and subthreshold swing (SS) = 0.64 V/dec. The stability behaviour of self-aligned top gate top contact a-IZO TFT fabricated by UV combination treatment was investigated under positive bias stress (PBS) and negative bias stress (NBS) with the smallest ∆V th of 2.4 V and 0.5 V for PBS and NBS, respectively. Our work shows that ∆Vth is improved due to reduction of interface trap density and moisture-related impurities especially on the activated electrode area. . As a result, it can be inferred that UV combination treatment is a simple and promising method to enhance the electrical and stability performance of a-IZO TFTs even at the low-temperature process, which is useful for flexible devices.