Preparation of Cellulose Nanofibers from Bamboo Using Microwave Liquefaction

Cellulose nanofibers isolated from renewable lignocellulosic biomass are considered highly promising fillers in preparing sustainable composite materials. Although previous technologies on the production of cellulose nanofibers were encouraging, drawbacks such as chemical reagent, high energy consumption, time-consumption, and equipment degradation have limited these techniques for practical applications. In this work, bamboo particles were subjected to microwave liquefaction process and the liquefied bamboo residues were characterized to have a better understanding of the liquefaction behaviors of bamboo. Then, the microwave liquefaction process was optimized for the production of cellulose raw materials and the isolation of cellulose nanofibers. The lignin fraction fractionated from the microwave liquefaction process was also characterized for use in bio-based materials. The overall results revealed that high conversion yield of bamboo to liquid could be archived in mild microwave liquefaction reaction conditions. Lignin and hemicellulose in bamboo could easily undergo decomposition during liquefaction, while cellulose was the main resistance to the liquefaction process. The chemical and morphology analysis results revealed that the liquefied bamboo residues retained fiber structure and cellulose. Bleaching and acid hydrolysis were proved to be effective in purifying the residues for pure white cellulose fibers by removing carboxyl groups and lignin fragments. Long nanofibrils were generated by subjecting the pure cellulose fibers to high-intensity ultrasonic treatment. Good quality fibers with high holocellulose content were successfully produced by removing lignin and extractives from bamboo when the microwave liquefaction temperature was below 120oC. The relative lignin and extractives contents of the liquefied residues from the reaction at 120 oC, 9min were as low as 0.65 and 0.49 %, respectively. Cellulose nanofibers with diameters in the range of 2-30 nm were successfully extracted from the cellulose materials with a subsequent chemical treatment as a purification process and ultrasonication as a nanofibrillation process. The main functionality of the microwave liquefaction process on the nanofiber preparation process was efficiently converting bamboo bundles into micro-sized fibers by almost completely removing lignins and extractives. The isolated cellulose nanofibers have potential application for the fabrication of thermally stable composites because of their high thermal stability. Lignins recovered from the microwave liquefaction system showed high purity and retained their natural structures. The lignin samples were completely soluble in ethanol/water, DMSO, THF, 1, 4-dioxane, and 1mol/L NaOH solution. Polylactic acid (PLA)-lignin composites were successfully fabricated, and the lignin component in the PLA-lignin blends significantly improved the UV light barrier properties of the composites. The utilization of the lignin fraction should enhance the economic value of the microwave liquefaction system on the integrated utilization of bamboo

Intelligent modeling with physics-informed machine learning for petroleum engineering problems

The advancement in big data and artificial intelligence has enabled a novel exploration mode for the study of petroleum engineering. Unlike theory-based solution methods, the data-driven intelligent approaches demonstrate superior flexibility, computational efficiency and accuracy for dealing with complex multi-scale, and multi-physics problems. However, these intelligent models often disregard physical laws in pursuit of error minimization, which leads to certain uncertainties. Therefore, physics-informed machine learning approaches have been developed based on data, guided by physics, and supported by machine learning models. This study summarizes four embedding mechanisms for introducing physical information into machine learning models, including input databased embedding, model architecture-based embedding, loss function-based embedding, and model optimization-based embedding mechanism. These “data + physics” dualdriven intelligent models not only exhibit higher prediction accuracy while adhering to physic laws, but also accelerate the convergence to improve computational efficiency. This paradigm will facilitate the guide developments in solving petroleum engineering problems toward a more comprehensive and efficient direction.Cited as: Xie, C., Du, S., Wang, J., Lao, J., Song, H. Intelligent modeling with physics-informed machine learning for petroleum engineering problems. Advances in Geo-Energy Research, 2023, 8(2): 71-75. https://doi.org/10.46690/ager.2023.05.0

Characterization of Biobased Polyurethane Foams Employing Lignin Fractionated from Microwave Liquefied Switchgrass

Lignin samples fractionated from microwave liquefied switchgrass were applied in the preparation of semirigid polyurethane (PU) foams without purification. The objective of this study was to elucidate the influence of lignin in the PU matrix on the morphological, chemical, mechanical, and thermal properties of the PU foams. The scanning electron microscopy (SEM) images revealed that lignin with 5 and 10% content in the PU foams did not influence the cell shape and size. The foam cell size became larger by increasing the lignin content to 15%. Fourier transform infrared spectroscopy (FTIR) indicated that chemical interactions occurred between the lignin hydroxyl and isocyanate revealing that lignin was well dispersed in the matrix materials. The apparent density of the foam with 10% lignin increased by 14.2% compared to the control, while the foam with 15% lignin had a decreased apparent density. The effect of lignin content on the mechanical properties was similar to that on apparent density. The lignin containing foams were much more thermally stable than the control foam as evidenced by having higher initial decomposition temperature and maximum decomposition rate temperature from the thermogravimetric analysis (TGA) profiles

Isoquercitrin alleviates pirarubicin-induced cardiotoxicity in vivo and in vitro by inhibiting apoptosis through Phlpp1/AKT/Bcl-2 signaling pathway

Introduction: Due to the cardiotoxicity of pirarubicin (THP), it is necessary to investigate new compounds for the treatment of THP-induced cardiotoxicity. Isoquercitrin (IQC) is a natural flavonoid with anti-oxidant and anti-apoptosis properties. Thus, the present study aimed to investigate the influence of IQC on preventing the THP-induced cardiotoxicity in vivo and in vitro.Methods: The optimal concentration and time required for IQC to prevent THP-induced cardiomyocyte damage were determined by an MTT assay. The protective effect was further verified in H9c2 and HCM cells using dichlorodihydrofluorescein diacetate fluorescent probes, MitoTracker Red probe, enzyme-linked immunosorbent assay, JC-1 probe, and real time-quantitative polymerase chain reaction (RT-qPCR). Rats were administered THP to establish cardiotoxicity. An electrocardiogram (ECG) was performed, and cardiac hemodynamics, myocardial enzymes, oxidative stress indicators, and hematoxylin-eosin staining were studied. Voltage-dependent anion channel 1 (VDAC1), adenine nucleotide translocase 1 (ANT1), and cyclophilin D (CYPD) were detected by qRT-PCR, and the Phlpp1/AKT/Bcl-2 axis proteins were detected by western blot, confirming that IQC markedly increased cell viability and superoxide dismutase (SOD) levels, diminished the levels of ROS and MDA, and elevated mitochondrial function and apoptosis in vivo and in vitro.Results: Results showed that IQC reduced THP-induced myocardial histopathological injury, electrocardiogram (ECG) abnormalities, and cardiac dysfunction in vivo. IQC also decreased serum levels of MDA, BNP, CK-MB, c-TnT, and LDH, while increasing levels of SOD and GSH. We also found that IQC significantly reduced VDAC1, ANT1, and CYPD mRNA expression. In addition, IQC controlled apoptosis by modulating Phlpp1/AKT/Bcl-2 signaling pathways. IQC markedly increased H9c2 and HCM cell viability and SOD levels, diminished the levels of ROS and MDA, and elevated mitochondrial function in H9c2 and HCM cells to defend against THP-induced cardiomyocyte apoptosis in vitro. The AKT inhibitor IMQ demonstrated that IQC lacked antioxidant and anti-apoptotic properties. Moreover, our data showed that IQC regulates Phlpp1 expression, thereby influencing the expression levels of p-AKT, cytochrome c, caspase-3, caspase-9, Bcl-2, and Bax.Discussion: In conclusion, our results indicate that IQC protects the changes in mitochondrial membrane permeability in cardiomyocytes by regulating the Phlpp1/AKT/Bcl-2 signaling pathway, inhibits the release of cytc from the mitochondrial inner membrane to the cytoplasm, forms apoptotic bodies, induces cell apoptosis, and reduces THP induced cardiotoxicity

Polyols from Microwave Liquefied Bagasse and Its Application to Rigid Polyurethane Foam

Bagasse flour (BF) was liquefied using bi-component polyhydric alcohol (PA) as a solvent and phosphoric acid as a catalyst in a microwave reactor. The effect of BF to solvent ratio and reaction temperatures on the liquefaction extent and characteristics of liquefied products were evaluated. The results revealed that almost 75% of the raw bagasse was converted into liquid products within 9 min at 150 °C with a BF to solvent ratio of 1/4. The hydroxyl and acid values of the liquefied bagasse (LB) varied with the liquefied conditions. High reaction temperature combining with low BF to solvent ratio resulted in a low hydroxyl number for the LB. The molecular weight and polydispersity of the LB from reactions of 150 °C was lower compared to that from 125 °C. Rigid polyurethane (PU) foams were prepared from LB and methylene diphenyl diisocyanate (MDI), and the structural, mechanical and thermal properties of the PU foam were evaluated. The PU foams prepared using the LB from high reaction temperature showed better physical and mechanical performance in comparison to those from low reaction temperature. The amount of PA in the LB has the ability of increasing thermal stability of LB-PU foams. The results in this study may provide fundamental information on integrated utilizations of sugarcane bagasse via microwave liquefaction process

Biomedical Applications of Electrets: Recent Advance and Future Perspectives

Recently, electrical stimulation, as a non-pharmacological physical stimulus, has been widely exploited in biomedical and clinical applications due to its ability to significantly enhance cell proliferation and differentiation. As a kind of dielectric material with permanent polarization characteristics, electrets have demonstrated tremendous potential in this field owing to their merits of low cost, stable performance, and excellent biocompatibility. This review provides a comprehensive summary of the recent advances in electrets and their biomedical applications. We first provide a brief introduction to the development of electrets, as well as typical materials and fabrication methods. Subsequently, we systematically describe the recent advances of electrets in biomedical applications, including bone regeneration, wound healing, nerve regeneration, drug delivery, and wearable electronics. Finally, the present challenges and opportunities have also been discussed in this emerging field. This review is anticipated to provide state-of-the-art insights on the electrical stimulation-related applications of electrets

Effect of Lignin Derivatives in the Bio-Polyols from Microwave Liquefied Bamboo on the Properties of Polyurethane Foams

Bamboo residues were subjected to a microwave-assisted liquefaction process for the production of crude bio-polyols (CBP). The fractionated bio-polyols (FBP) were obtained by the removal of lignin derivatives from the crude bio-polyols (CBP) using a simple method. Polyurethane (PU) foams were successfully prepared from both CBP and FBP. The object of this study was to evaluate the effect of lignin derivatives in bio-polyols on the physical properties, thermal stability, and microstructure of PU foams. The results revealed that the PU foam made from CBP had a higher density and superior thermal stability compared to that made from FBP; however, they were also much more fragile. Scanning electron microscope (SEM) images indicated that the lignin compounds in the CBP had impact on the structure of the PU foam

Agricultural and Forest Residues towards Renewable Chemicals and Materials Using Microwave Liquefaction

Microwave-assisted liquefaction is regarded as a promising thermochemical approach to produce renewable and sustainable chemicals and materials from lignocellulosic biomass. Agricultural and forest residues as sources of lignocellulosic biomass have great potential in this regard. With process optimizations, several biomass types have been subjected to liquefaction in different solvents with various catalysts. The products from recent microwave liquefaction with and without further fractionation have been thoroughly analyzed and used for the synthesis of biomaterials. Renewable chemicals, polyurethane foams with partial use of renewable raw materials, and phenolic resins have been the main products from microwave-liquefied products. Further research on microwave liquefaction mechanisms and scalable production should be enhanced to fully evaluate the economic and environmental benefits. This work presents an overview on achievements using liquefaction in combination with microwave energy to convert lignocellulosic biomass into value-added products and chemicals

Analysis of Components and Properties of Extractives from Alnus cremastogyne Pods from Different Provenances

Chemical components with anti-oxidant, anti-inflammatory, and anti-cancer properties extracted from Alnus bark and leaves have been extensively studied. However, less attention has been paid to extractives from Alnus pods, which are mostly treated as waste. Here, extractives of Alnus cremastogyne pods from 12 provenances in Sichuan Province were studied for high value-added utilization of Alnus waste. The extractives were analyzed by Gas Chromatography-Mass Spectrometer (GC-MS), Ultraviolet-visible spectroscopy (UV-Vis spectra), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. A total of 58, 49, and 51 chemical components were found when the organic solvents of ethanol, petroleum ether, and ethyl acetate were used to collect extractives, respectively. These chemical components including Phytol, CIS-5,8,11,14,17-eicosapentaenoic acid, Germacrene D, Lupeol, and β-sitosterol, etc., have wide applications in the fields of pharmacy and cosmetics. Moreover, it was also found that extractives in ethanol and ethyl acetate had impressive UV resistance, especially for UV-C and UV-B blocking. The results showed that the maximum block ratio towards UV-C and UV-B could reach 99%. In addition, the ethanol extract showed good anti-oxidant activity with a maximum free radical scavenging rate of 96.19%. This comprehensive and systematic study on extractives from Alnus cremastogyne pods promotes the development of high-value utilization of Alnus components

Dilute Alkali and Hydrogen Peroxide Treatment of Microwave Liquefied Rape Straw Residue for the Extraction of Cellulose Nanocrystals

Microwave-assisted liquefaction of rape straw in methanol was conducted to collect the liquefied residues for the extraction of cellulose nanocrystals (CNCs). The liquefied residue with content of 23.44% from 180°C/7.5 min was used to fibrillate CNCs with dilute alkali (2% NaOH) and hydrogen peroxide (5% H2O2) treatments, followed by ultrasonication for 15 min. The FT-IR spectra and SEM images revealed that the liquefied residue from 180°C/7.5 min exhibited a relatively homogeneous texture and a huge surface with cellulose as core structure. The retained hemicelluloses and other impurities in the liquefied residue were eliminated by 2% NaOH treatment, and the surface and accessibility of the alkali treated sample were significantly increased by 5% H2O2 treatment. The TEM images confirmed the CNCs had an average diameter of 12.59 nm. The CNCs had good thermal stability with a maximum weight loss temperature of 376.5°C