Chemical and Electrochemical Properties of Bamboo Activated Carbon Activate Using Potassium Hydroxide Assisted by Microwave-Ultrasonic Irradiation

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.

Lignin-Derived Syringol and Acetosyringone from Palm Bunch Using Heterogeneous Oxidative Depolymerization over Mixed Metal Oxide Catalysts under Microwave Heating

Biomass valorization to building block chemicals in food and pharmaceutical industries has tremendously gained attention. To produce monophenolic compounds from palm empty fruit bunch (EFB), EFB was subjected to alkaline hydrothermal extraction using NaOH or K2CO3 as a promotor. Subsequently, EFB-derived lignin was subjected to an oxidative depolymerization using Cu(II) and Fe(III) mixed metal oxides catalyst supported on γ-Al2O3 or SiO2 as the catalyst in the presence of hydrogen peroxide. The highest percentage of total phenolic compounds of 63.87 wt% was obtained from microwave-induced oxidative degradation of K2CO3 extracted lignin catalyzed by Cu-Fe/SiO2 catalyst. Main products from the aforementioned condition included 27.29 wt% of 2,4-di-tert-butylphenol, 19.21 wt% of syringol, 9.36 wt% of acetosyringone, 3.69 wt% of acetovanillone, 2.16 wt% of syringaldehyde, and 2.16 wt% of vanillin. Although the total phenolic compound from Cu-Fe/Al2O3 catalyst was lower (49.52 wt%) compared with that from Cu-Fe/SiO2 catalyst (63.87 wt%), Cu-Fe/Al2O3 catalyst provided the greater selectivity of main two value-added products, syringol and acetosyrigone, at 54.64% and 23.65%, respectively (78.29% total selectivity of two products) from the NaOH extracted lignin. The findings suggested a promising method for syringol and acetosyringone production from the oxidative heterogeneous lignin depolymerization under low power intensity microwave heating within a short reaction time of 30 min.

A Rapid and Convenient Approach to Construct Porous Collagen Membranes via Bioskiving and Sonication-Feasible for Mineralization to Induce Bone Regeneration

Porous mineralized collagen membranes efficiently promote bone regeneration. To generate them, we need to fabricate collagen membranes that are porous. However, the current fabrication method is primarily based on a bottom-up strategy, with certain limitations, such as a long manufacturing process, collagen denaturation, and failure to control fibril orientation. Using a top-down approach, we explore a novel method for constructing porous collagen membranes via the combined application of bioskiving and sonication. Numerous collagen membranes with well-aligned fibril structures were rapidly fabricated by bioskiving and then sonicated at 30, 60, 90, and 120 W for 20 min. This treatment allowed us to study the effect of power intensity on the physicochemical traits of collagen membranes. Subsequently, the prepared collagen membranes were immersed in amorphous calcium phosphate to evaluate the feasibility of mineralization. Additionally, the bioactivities of the membranes were assessed using preosteoblast cells. Tuning the power intensity was shown to modulate fibril orientation, and the porous membrane without denatured collagen could be obtained by a 20-min sonication treatment at 90 W. The prepared collagen membrane could also be further mineralized to enhance osteogenesis. Overall, this study offers a rapid and convenient approach for fabricating porous collagen membranes via bioskiving and sonication.

Bioaccessibility, antioxidant and antibacterial potentials of phenolic compounds ultrasonically extracted from acerola Malpighiaglabra DC coproduct

Background: This study assessed the effects of solvent proportion, time, and power intensity of ultrasound processing on the extraction,bioaccessibility, antioxidant and antimicrobial activity of phenolic compounds (PC) from acerola (Malpighia glabra DC) coproduct (ACP). Methods: The ultrasound process with water as a solvent in a ratio of 1:2, power intensity of 75 W/cm2 during 10 min was selected as the optimal condition to provide higher extraction of the total phenolic compounds (4126 mg gallic acid.100 g-1 with total antioxidant activity of 98.62 μMTrolox.g-1). Power intensity and solid: solvent proportion were the parameters that increased the total PC quantification. The main phenolic compounds from the ACP tentatively identified by UPLC-ESI-QTOF-MS/MS were rutin, luteolin, and quercetin. Ultrasound extraction also improved antimicrobial activity against Listeria monocytogenes and Staphylococcus aureus(40 mg.L -1). Results: These results indicate that antioxidant and antimicrobial activities in the ACP phenolic extracts are quite potent and implicate the presence of compounds with potent free-radical-scavenging activity. Conclusion: It is possible to extract phenolic compounds from acerola coproducts using sustainable “green” technology, only using water as a solvent and ultrasound processing.

Evaluation of Compact Boundary of Outage Probability in HetNet

In this paper, we investigate the outage probability of per-tier in heterogeneous networks (HetNet) in the presence of aggregated interference from coexisting ad hoc networks. In ad hoc networks, a receiving node suffers the cross-tier interference signal from cellular cell and aggregated interference signal from other transmitting nodes. In order to evaluate the effect of cross-tier interference on the outage probability of ad hoc networks, we analyze the restricted region in cellular cell that the received signal interference noise ratio (SINR) of a receiving node does not exceed the SINR threshold considering the path loss model. Further, to evaluate the effect of aggregated interference of ad hoc networks, we divide the plane area into near-field area and far-field area according to whether the signal of a transmitting node could cause an outage independently or not. Based on this division, we derive the compact lower and upper boundaries of outage probability of per-tier. The computer simulations validate the results of theoretical analysis and show the effect of different factors, such as transmit power, intensity of ad hoc nodes, on the outage probability.

Preparation of hexagonal nanoporous Al2O3/TiO2/TiN as a novel photodetector with high efficiency

The unique optical properties of metal nitrides enhance many photoelectrical applications. In this work, a novel photodetector based on TiO2/TiN nanotubes was deposited on a porous aluminum oxide template (PAOT) for light power intensity and wavelength detection. The PAOT was fabricated by the Ni-imprinting technique through a two-step anodization method. The TiO2/TiN layers were deposited by using atomic layer deposition and magnetron sputtering, respectively. The PAOT and PAOT/TiO2/TiN were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). The PAOT has high-ordered hexagonal nanopores with dimensions ~ 320 nm pore diameter and ~ 61 nm interpore distance. The bandgap of PAOT/TiO2 decreased from 3.1 to 2.2 eV with enhancing absorption of visible light after deposition of TiN on the PAOT/TiO2. The PAOT/TiO2/TiN as photodetector has a responsivity (R) and detectivity (D) of 450 mAW-1 and 8.0 × 1012 Jones, respectively. Moreover, the external quantum efficiency (EQE) was 9.64% at 62.5 mW.cm−2 and 400 nm. Hence, the fabricated photodetector (PD) has a very high photoelectrical response due to hot electrons from the TiN layer, which makes it very hopeful as a broadband photodetector.

Production of Low Molecular Weight Chitosan and Chitooligosaccharides (COS): A Review

Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan. Acid hydrolysis is still the most used method to obtain low molecular weight chitosan and chitooligosaccharides. However, the use of acids can generate environmental impacts. When different methods are combined, gamma radiation and microwave power intensity are the variables that most influence acid hydrolysis. Otherwise, in oxidative hydrolysis with hydrogen peroxide, a long time is the limiting factor. Thus, it was observed that the most efficient method is the association between the different hydrolysis methods mentioned. However, this alternative can increase the cost of the process. Enzymatic hydrolysis is the most studied method due to its environmental advantages and high specificity. However, hydrolysis time and process cost are factors that still limit industrial application. In addition, the enzymatic method has a limited association with other hydrolysis methods due to the sensitivity of the enzymes. Therefore, this article seeks to extensively review the variables that influence the main methods of hydrolysis: acid concentration, radiation intensity, potency, time, temperature, pH, and enzyme/substrate ratio, observing their influence on molecular weight, yield, and characteristic of the product.

Ultrasound-Mediated Cavitation Enhances EGFR-Targeting PLGA-PEG Nano-Micelle Delivery for Triple-Negative Breast Cancer Treatment

Triple-negative breast cancer (TNBC) is highly recurring and metastatic breast cancer with overexpressing epidermal growth factor receptor (EGFR). Herein, a series of in vitro and in vivo analyses were used to explore the therapeutic effect of EGFR-targeting nano-micelles (PLGA-PEG/DOX@anti-EGFR) combined with ultrasound-mediated cavitation (UMC). The prepared nano-micelle drug carriers have good biocompatibility and can greatly increase the drug accumulation in tumor regions, thereby reducing off-target toxicity while enhancing anti-tumor efficacy. Moreover, an in vivo analysis of the practical utility of this treatment modality was conducted by using SonoVueTM microbubbles to achieve cavitation under different power intensity levels, with an ultrasonic power intensity of 0.5 W/cm2 maximizing the intra-tumoral blood perfusion. Relative to PLGA-PEG@DOX/anti-EGFR nano-micelles treatment alone, the combination with UMC was better able to suppress tumor growth even at low concentrations. As such, combining actively targeted drug-carrier molecules with UMC represents an effective approach to enhancing therapeutic efficacy while reducing the adverse, systemic effects associated with DOX and other chemotherapeutic drugs, and it can be considered as a promising clinical prospect in the treatment of TNBC.

Intermittent Ultrasound-Assisted Ceramic Membrane Fouling Control in Ultrafiltration

Ultrafiltration is one of the most promising membrane technologies for liquid purification due to its high economic efficiency in the industries. However, it has been faced with a critical problem, called fouling. The contaminants in feed solution tend to accumulate on the membrane surface, hindering permeate solution to pass through the porous spaces. Among the various solutions, application of ultrasound has been considered as the most popular method since it does not suffer a disadvantage of downtime and the filtration process does not need to be stopped for the removal of foulants. In this study, control of ceramic membrane fouling by an on-line intermittent ultrasound system was being investigated. The experiment focused on obtaining optimal operating ultrasonic condition. Frequency (20, 28, and 40 kHz), power intensity (1.44, 2.88, and 5.76W/cm2 ), and time interval of intermittent ultrasound (1, 1.5, and 2 minutes) were the parameters of interest. The effect of feed concentration was also analyzed at optimal ultrasonic condition. The quality and flow rate of the permeate streams were monitored for the evaluation of the process performance. The optimal condition of intermittent ultrasound was found at the frequency of 28 kHz and the power intensity of 2.88 W/cm2 ; and then, the application of intermittent ultrasound with short time interval successfully reduced the operating cost of ultrafiltration process while maintaining acceptable quality and flow rate of permeate solution. There was increase in efficiency of intermittent ultrasound at lower feed concentration.