Improved antioxidant activity of pretreated lignin nanoparticles: Evaluation and self-assembly.

Lignin nanoparticles (LNPs) have gained significant attention for their potential as natural antioxidants. This study investigated the effect of various pretreatment methods on the lignin structure and subsequent antioxidant activity of LNPs. Among four pretreated LNPs, hydrothermal LNPs exhibited the highest antioxidant activity, surpassing unpretreated, acid-pretreated and kraft LNPs, with an impressive efficacy of 91.6%. The relationship between LNPs' structure and antioxidant activity was revealed by 2D heteronuclear singular quantum correlation (1H13C HSQC) and 31P nuclear magnetic resonance (NMR). 1H13C HSQC suggested the cleavage of ß-O-4 ether bonds, as well as a decrease in ferulic acid and p-coumaric acid, which directly influenced the antioxidant activity of LNPs. 31P NMR demonstrated a positive correlation between the total hydroxyl group content and the antioxidant activity. Besides, an isothermal kinetic model for scavenging free radicals was established based on Langmuir kinetic model instead of Freundlich model. Moreover, multilayer LNPs, based on layer-by-layer self-assembly, were prepared and exhibited remarkable antioxidant activity of 95.8%. More importantly, when blended with pure cosmetic cream, the multilayer LNPs maintained antioxidant activity of 86.7%. These finding may promote the practical applications of biomolecules, e.g. lignin additives in cosmetics and pharmaceuticals.

Formation of cation bridges and its promoting mechanism for sorption of sulfamethoxazole by montmorillonite.

The coexistence of metal cations is often accompanied by organic pollution and could affect the environmental fate of organics by mediating the formation of cation bridges. However, the environmental fate and risk of organics in cation co-existing environments are poorly understood due to the lack of accurate identification of cation bridge formation and stability. In this study, the sorption of sulfamethoxazole (SMX) on montmorillonite (MT) with the coexistence of three different valence metal cations (Na+, Ca2+, and Cr3+) was investigated. Ca2+ and Cr3+ can significantly promote the sorption of SMX on MT for about 5∼10 times promotion, respectively, while Na+ bridges displayed little effect on the sorption of SMX. The sorption binding energy of SMX with MT-Ca (-44.01 kcal/mol) and MT-Cr (-64.57 kcal/mol) bridges was significantly lower than that with MT-Na (-38.45 kcal/mol) and MT (-39.39 kcal/mol), indicating that the sorption affinity of SMX on Cr and Ca bridges was much stronger. The higher valence of the cations also resulted in a more stable adsorbed SMX with less desorption fluctuation. In addition, the relatively higher initial concentration of SMX and the valence of cations increased the bonding density of the cation bridges, thus promoting the apparent sorption of SMX on MT to a certain extent. This work reveals the formation and function of cation bridges in the sorption of SMX on MT. It lays a theoretical foundation for further understanding the environmental fate and risk of organics.

Aluminum ion intercalation in mesoporous multilayer carbocatalysts promotes the conversion of glucose to 5-hydroxymethylfurfural.

In this study, an efficient modification strategy was proposed by facile loading of trace aluminum ions and p-toluene sulfonic acid (p-TSA) in carbon materials to improve their catalytic activity. p-TSA is then proven to regulate the carbonization process and promote the formation of mesoporous and multilayer structures. The hexa-coordinated aluminum structure is characterized by 1H-27Al solid-state nuclear magnetic resonance (SSNMR) and X-ray photoelectron spectroscopy, which serves as the Lewis-Brønsted acid site in carbocatalysts. Accordingly, the resulting catalyst facilitates a yield of ∼70% for converting glucose to 5-hydroxymethylfurfural (HMF) with a maximum carbon balance of around 91.4% at 150 °C in 6 h. In situ NMR, electrospray ionization mass spectrometry and isotope labeling analysis reveal that the hexa-coordinated aluminum sites promote the isomerization of glucose, and the sulfonic groups facilitate the subsequent dehydration and rehydration of fructose and levoglucosan intermediates. Kinetic models further indicate the decreased energy barrier for glucose conversion over the Al3+/p-TSA intercalated carbocatalyst. This work provides a promising strategy for engineering waste-derived carbocatalysts toward effectively converting carbohydrates to precursors of biofuels and bioplastics.

On-Demand Energy Transfer and Energy-Aware Polling-Based MAC for Wireless Powered Sensor Networks.

To improve the performance of the wireless powered sensor network (WPSN), this paper proposes a frequency division duplex (FDD)-based on-demand energy transfer protocol and an energy-aware polling-based medium access control (MAC) protocol, called composite energy and data first (CEDF), by using the numbers of data packets and energy packets to determine polling priorities. The performance of the proposed MAC protocol, i.e., CEDF, along with the on-demand energy transfer protocol was evaluated through simulations, with comparison to the closely related protocols such as the round robin (RR) and data first (DF) polling protocols. Compared with RR and DF, our proposed CEDF performs much better in terms of throughput, data packet loss rate, and delay. Additionally, the doubly near-far problem in WPSNs under our proposed on-demand energy transfer protocol and CEDF was investigated to come up with good solutions to alleviate such a problem.

Chloroplast Genome Evolution and Species Identification of Styrax (Styracaceae).

The genus Styrax L. consists of approximately 130 species distributed in the Americas, eastern Asia, and the Mediterranean region. The phylogeny and evolutionary history of this genus are not clear. Knowledge of the phylogenetic relationships and the method for species identification will be critical for the evolution of this genus. In this study, we sequenced the chloroplast genome of 17 Styrax samples and added 17 additional chloroplast genome sequences from GenBank. The data were used to investigate chloroplast genome evolution, infer phylogenetic relationships, and access the species identification rate within Styrax. The Styrax chloroplast genome contains typical quadripartite structures, ranging from 157,641 bp to 159,333 bp. The chloroplast genome contains 114 unique genes. The P distance among the Styrax species ranged from 0.0003 to 0.00611. Seventeen small inversions and SSR sites were discovered in the Styrax chloroplast genome. By comparing with the chloroplast genome sequences, six mutation hotspots were identified, and the markers ycf1b and trnT-trnL were identified as the best Styrax-specific DNA barcodes. The specific barcodes and superbarcode exhibited higher discriminatory power than universal barcodes. Chloroplast phylogenomic results improved the resolution of the phylogenetic relationships of Styrax compared to previous analyses.

Comparative Analysis of the Chloroplast Genome for Four Pennisetum Species: Molecular Structure and Phylogenetic Relationships.

The genus Pennisetum (Poaceae) is both a forage crop and staple food crop in the tropics. In this study, we obtained chloroplast genome sequences of four species of Pennisetum (P. alopecuroides, P. clandestinum, P. glaucum, and P. polystachion) using Illumina sequencing. These chloroplast genomes have circular structures of 136,346-138,119 bp, including a large single-copy region (LSC, 79,380-81,186 bp), a small single-copy region (SSC, 12,212-12,409 bp), and a pair of inverted repeat regions (IRs, 22,284-22,372 bp). The overall GC content of these chloroplast genomes was 38.6-38.7%. The complete chloroplast genomes contained 110 different genes, including 76 protein-coding genes, 30 transfer RNA (tRNA) genes, and four ribosomal RNA (rRNA) genes. Comparative analysis of nucleotide variability identified nine intergenic spacer regions (psbA-matK, matK-rps16, trnN-trnT, trnY-trnD-psbM, petN-trnC, rbcL-psaI, petA-psbJ, psbE-petL, and rpl32-trnL), which may be used as potential DNA barcodes in future species identification and evolutionary analysis of Pennisetum. The phylogenetic analysis revealed a close relationship between P. polystachion and P. glaucum, followed by P. clandestinum and P. alopecuroides. The completed genomes of this study will help facilitate future research on the phylogenetic relationships and evolution of Pennisetum species.

Effect of organosolv extraction on the structure and antioxidant activity of eucalyptus kraft lignin.

In this study, three lignin fractions F1, F2, and F3 were obtained from eucalyptus kraft lignin (EKL) by solvent extraction with ethyl acetate, acetone, and acetone/water. The antioxidant activity of these lignin fractions were measured and evaluated by using the DPPH radical scavenging activity, ABTS radical cation scavenging activity and ferric reducing antioxidant power analysis. These lignin fractions were also characterized by applying Gel permeation chromatography, Fourier transform infrared, 31P NMR and 2D HSQC NMR techniques. The three different lignin fractions had rather different average molecular sizes, as well as different phenolic and methoxy functional contents. The ethyl acetate fraction (F1) with the lowest average molecular weight (2342 g/mol) and the highest phenolic hydroxyl content (4.2457 mmol/g) and methoxy groups (6.2714 mmol/g) showed high homogeneity and the highest antioxidant activity. Its DPPH scavenging activity, ABTS+ scavenging activity, and ferric reducing the antioxidant power were 68.67%, 75.57%, and 91.89 µmol/g, respectively. Moreover, the antioxidant activity of F1 and F2 was found to be higher than that of butylated hydroxytoluene. Therefore, solvent extraction was shown to be an effective way to separate lignin fractions with high homogeneity, high antioxidant activity, which could lead to application of lignin with higher value.

Effect of Pretreatments on the Enzymatic Hydrolysis of High-Yield Bamboo Chemo-Mechanical Pulp by Changing the Surface Lignin Content.

Hydrogen peroxide chemo-mechanical pulp (APMP), sulfonated chemo-mechanical pulp (SCMP), and chemical thermomechanical pulp (CTMP) were used as raw materials to explore the effects of hydrogen peroxide (HP), Fenton pretreatment (FP), and ethanol pretreatment (EP) on the enzymatic hydrolysis of high-yield bamboo mechanical pulp (HBMP). The surface lignin distribution and contents of different HBMPs were determined using confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The correlation between the surface lignin and the enzymatic hydrolysis of HBMP was also investigated. The residue of enzymatic hydrolysis was used to adsorb methylene blue (MB). The results showed that the cracks and fine fibers on the surface of APMP, SCMP, and CTMP increased after FP, when compared to HP and EP. The total removal content of hemicellulose and lignin in SCMP after FP was higher than with HP and EP. Compared to SCMP, the crystallinity increased by 15.4%, and the surface lignin content of Fenton-pretreated SCMP decreased by 11.7%. The enzymatic hydrolysis efficiency of HBMP after FP was higher than with HP and EP. The highest enzymatic hydrolysis of Fenton-pretreated SCMP was 49.5%, which was higher than the enzymatic hydrolysis of Fenton-pretreated APMP and CTMP. The removal rate of MB reached 94.7% after the adsorption of the enzymatic hydrolysis residue of SCMP. This work provides an effective approach for a high value-added utilization of high-yield bamboo pulp.

Flexible conductive hydrogel fabricated with polyvinyl alcohol, carboxymethyl chitosan, cellulose nanofibrils, and lignin-based carbon applied as strain and pressure sensor.

Employing renewable, environmentally friendly, low-cost lignocellulose to design flexible pressure sensitive hydrogel (PSH) as strain and pressure sensors in wearable electronics represents the global perspective to build sustainable and green society. Lignin-based carbon (LC), as the conductive filler, were uniform distributed in the hydrogel system composing by polyvinyl alcohol (PVA), carboxymethyl chitosan (CMC), and cellulose nanofibrils (CNF) to assemble PSH. The analysis revealed that the cross-linking of components through hydrogen bonds formed among hydroxyl group, amino group and carboxyl group exerts the hydrogel with stretching ability and fatigue resistance. The results indicated that the fracture tensile strength and compression stress of the PC/CNF/LC hydrogel were 133 kPa and 37.7 kPa, respectively. Because of the existence of LC, PSH hydrogel exhibits the sensitive deformation-dependent conductivity and can be applied as a flexible strain and pressure sensor monitoring body motions such as elbow flexion, finger bend and palm grip. Therefore, the assembled PSH hydrogel is a prominent candidate applying as the strain and pressure sensor devices.

In situ growth gold nanoparticles in three-dimensional sugarcane membrane for flow catalytical and antibacterial application.

In this work, we decorated gold nanoparticles (Au NPs) in the porous, three-dimensional sugarcane membrane for the flow catalytical and antibacterial application. Due to the uniformly distributed Au NPs in sugarcane channels and the porous structure of sugarcane, the interaction between contaminant and catalysis was enhanced as water flowing through the Au NPs/sugarcane membrane. The Au NPs/sugarcane membrane exhibited superior catalytical efficiency for removing methylene blue (MB) with a turn over frequency of 0.27 molMB·molAu-1·min-1 and the water treatment rate reached up to 1.15×105 L/m2 h with >98.3 % MB removal efficiency. The Au NPs/sugarcane membrane also exhibited superior bacterial removal efficiency as E. coli suspension flowing through it, due to the superimposition effects of physical barrier in sugarcane and the antibacterial property of Au NPs. The tremendous catalytical and antibacterial performance of Au NPs/sugarcane membrane provides a promising potential for the rational design of flow catalytical membrane reactor to purify the microbial contaminated water.

Electrocoagulation pre-treatment to simultaneously remove dissolved and colloidal substances and Ca2+ in old corrugated container wastewater.

An effective electrocoagulation pre-treatment (ECP) method was proposed to simultaneously solve the problems of the micro stickies deposition and high Ca2+ content in old corrugated container (OCC) papermaking wastewater during the recycling process. The optimal ECP condition was investigated. The results indicated that the effect of an Al electrode on wastewater treatment was superior to that of a Fe or Mg electrode. The optimal treatment conditions of the current density, electrode distance and reaction time were 115 A m-2, 5 cm and 60 min, respectively. After the ECP, the chemical oxygen demand (COD) and Ca2+ removal rates were 75.33% and 64.53%, respectively, and the turbidity and dissolved and colloidal substance (DCS) content decreased by 97.1% and 43.68%, respectively. The particle size of flocs in the liquid increased from 1.675 µm to 31.97 µm, and the floc content was 0.78 g L-1 after ECP. The anode material and energy consumption were 0.1846 kg m-3 and 4.56 kWh m-3, respectively, and the cost of treatment was estimated to be 1.11 $ m-3. The results demonstrate that ECP can effectively remove the micro stickies, COD, and Ca2+ in the OCC wastewater, which is conducive to reducing the cost of wastewater treatment and conform to the requirements of sustainable development.

Impact of bagasse lignin-carbohydrate complexes structural changes on cellulase adsorption behavior.

Pretreatment technology has attracted much attention as an effective method for the conversion of sugarcane bagasse into biochemicals. However, residual lignin-carbohydrate complexes (LCC) can negatively impact the subsequent enzymatic hydrolysis of bagasse. In this work, the changes in bagasse LCC after pretreatment with hot water and dilute acid were characterized by component analysis, 13C NMR and 1H-13C HSQC NMR to reveal the correlation between LCC structure and cellulase adsorption. A real-time dynamic model of LCC affecting adsorption of cellulase was constructed using a quartz crystal microbalance (QCM-D). The QCM-D results demonstrated that cellulase exhibited different adsorption characteristics on different LCCs. For example, the maximum adsorption capacities for cellulase onto the raw material LCC (RW-LCC), hot water pretreated LCC (LHW-LCC), and dilute acid pretreated LCC (AP-LCC) at 4 °C were 29.0 ng/cm2, 94.9 ng/cm2 and 129.8 ng/cm2, respectively. In addition, the adsorption rate constants for cellulase on RM-LCC, LHW-LCC and AP-LCC at 4 °C were 0.09, 0.14 and 0.19, respectively.

Nano MnO2 Radially Grown on Lignin-Based Carbon Fiber by One-Step Solution Reaction for Supercapacitors with High Performance.

MnO2-deposited lignin-based carbon fiber (MnO2-LCF) mats are fabricated for supercapacitor applications. LCF mats are produced from alkali lignin via electrospinning followed by stabilization and carbonization. The carbonization process is carried out at 800, 900, and 1000 °C, and the corresponding mats are denoted as MnO2-LCF-800, MnO2-LCF-900, and MnO2-LCF-1000, respectively. The LCF mats are immersed in a KMnO4 solution at room temperature for 72 h to obtain MnO2-LCF mats. The scanning electron microscopy and X-ray diffraction analysis confirm the deposition of MnO2 on the LCFs. The Brunauer-Emmett-Teller analysis, X-ray spectroscopy, and Raman spectroscopy reveal that MnO2-LCF-800 mat possesses a large number of mesopores and Mn vacancies as compared to MnO2-LCF-900 mat and MnO2-LCF-1000 mat. Consequently, MnO2-LCF-800 mat possesses the best electrochemical properties with a specific capacitance of 131.28 F∙g-1, an energy density of 14.77 Wh∙kg-1, and a power density of 135.01 W∙kg-1 at a specific current of 0.3 A∙g-1. Hence, MnO2-LCF-800 mat shows high potential to be used as a high-performance supercapacitor.

Comparing impacts of physicochemical properties and hydrolytic inhibitors on enzymatic hydrolysis of sugarcane bagasse.

An autohydrolysis pretreatment with different conditions was applied to sugarcane bagasse to compare the impacts of the physicochemical properties and hydrolytic inhibitors on its enzymatic hydrolysis. The results indicate that the autohydrolysis conditions significantly affected the physicochemical properties and inhibitors, which further affected the enzymatic hydrolysis. The inhibitor amount, pore size, and crystallinity degree increased with increasing autohydrolysis severity. Furthermore, the enzymatic hydrolysis was enhanced with increasing severity owing to the removal of hemicellulose and lignin. The physicochemical obstruction impeded the enzymatic hydrolysis more than the inhibitors. The multivariate correlated component regression analysis enabled an evaluation of the correlations between the physicochemical properties (and inhibitors) and enzymatic hydrolysis for the first time. According to the results, an autohydrolysis with a severity of 4.01 is an ideal pretreatment for sugarcane bagasse for sugar production.

Fabrication of Lignin-Based Nano Carbon Film-Copper Foil Composite with Enhanced Thermal Conductivity.

Technical lignin from pulping, an aromatic polymer with ~59% carbon content, was employed to develop novel lignin-based nano carbon thin film (LCF)-copper foil composite films for thermal management applications. A highly graphitized, nanoscale LCF (~80-100 nm in thickness) was successfully deposited on both sides of copper foil by spin coating followed by annealing treatment at 1000 °C in an argon atmosphere. The conditions of annealing significantly impacted the morphology and graphitization of LCF and the thermal conductivity of LCF-copper foil composite films. The LCF-modified copper foil exhibited an enhanced thermal conductivity of 478 W m-1 K-1 at 333 K, which was 43% higher than the copper foil counterpart. The enhanced thermal conductivity of the composite films compared with that of the copper foil was characterized by thermal infrared imaging. The thermal properties of the copper foil enhanced by LCF reveals its potential applications in the thermal management of advanced electronic products and highlights the potential high-value utility of lignin, the waste of pulping.

How Pseudo-lignin Is Generated during Dilute Sulfuric Acid Pretreatment.

Pseudo-lignin is generated from lignocellulose biomass during pretreatment with dilute sulfuric acid and has a significant inhibitory effect on cellulase. However, the mechanism of pseudo-lignin generation remains unclear. The following main points have been addressed to help elucidate the pseudo-lignin generation pathway. Cellulose and xylan were pretreated with sulfuric acid at different concentrations; aliquots were periodically collected; and the changes in the byproducts of the prehydrolysate were quantified. Milled wood lignin (MWL) mixed with cellulose and xylan was pretreated to evaluate the impact of lignin on pseudo-lignin generation. Furfural, 5-hydroxymethylfurfural, and MWL were pretreated as model compounds to investigate pseudo-lignin generation. The result indicated that the increasing acid concentration significantly promoted the generation of pseudo-lignin. When the acid concentration was increased from 0 to 1.00 wt %, pseudo-lignin was increased from 1.36 to 4.05 g. In addition, lignin promoted the pseudo-lignin generation through the condensation between lignin and the generated intermediates.

Comparative Chloroplast Genomes of Sorghum Species: Sequence Divergence and Phylogenetic Relationships.

Sorghum comprises 31 species that exhibit considerable morphological and ecological diversity. The phylogenetic relationships among Sorghum species still remain unresolved due to lower information on the traditional DNA markers, which provides a limited resolution for identifying Sorghum species. In this study, we sequenced the complete chloroplast genomes of Sorghum sudanense and S. propinquum and analyzed the published chloroplast genomes of S. bicolor and S. timorense to retrieve valuable chloroplast molecular resources for Sorghum. The chloroplast genomes ranged in length from 140,629 to 140,755 bp, and their gene contents, gene orders, and GC contents were similar to those for other Poaceae species but were slightly different in the number of SSRs. Comparative analyses among the four chloroplast genomes revealed 651 variable sites, 137 indels, and nine small inversions. Four highly divergent DNA regions (rps16-trnQ, trnG-trnM, rbcL-psaI, and rps15-ndhF), which were suitable for phylogenetic and species identification, were detected in the Sorghum chloroplast genomes. A phylogenetic analysis strongly supported that Sorghum is a monophyletic group in the tribe Andropogoneae. Overall, the genomic resources in this study could provide potential molecular markers for phylogeny and species identification in Sorghum.

Fe3O4Nanoparticles Loaded on Lignin Nanoparticles Applied as a Peroxidase Mimic for the Sensitively Colorimetric Detection of H2O2.

Lignin is the second largest naturally renewable resource and is primarily a by-product of the pulp and paper industry; however, its inefficient use presents a challenge. In this work, Fe3O4 nanoparticles loaded on lignin nanoparticles (Fe3O4@LNPs) were prepared by the self-assembly method and it possessed an enhanced peroxidase-like activity. Fe3O4@LNPs catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to generate a blue color, was observable by the naked eye. Under the optimal conditions, Fe3O4@LNPs showed the ability of sensitive colorimetric detection of H2O2within a range of 5⁻100 µM and the limit of detection was 2 µM. The high catalytic activity of Fe3O4@LNPs allows its prospective use in a wide variety of applications, including clinical diagnosis, food safety, and environmental monitoring.

Characterization of the complete chloroplast genome sequence of Pennisetum glaucum and its phylogenetic implications.

Pennisetum glaucum is a high nutritive-value summer-annual forage crop, popular among livestock producers for grazing, silage, hay, and green chop. In this study, the complete chloroplast genome of the P. glaucum was assembled from the whole genome Illumine sequencing data. The size of the P. glaucum chloroplast genome is 138,119 bp, including a large single-copy region (81,034 bp), a small single-copy region (12,409 bp), and a pair of inverted repeats regions (22,338 bp). The overall GC content of the P. glaucum chloroplast genome was 38.6%. The chloroplast genome of P. glaucum encodes 110 different genes, including 76 protein-coding genes, 30 transfer RNAs (tRNA), and four ribosomal RNAs (rRNA). Phylogenetic analysis confirmed a close relationship of P. glaucum with species in the Panicoideae subfamily of the Poaceae family.

Characterization of complete chloroplast genome of traditional Chinese medical plants Paris Mairei and its phylogenetic positions.

The genus Paris (Liliaceae) has been used for traditional medicine in China. The wild Paris was on the verge of exhaustion due to illegal and immoderate exploitation coupled with environmental pollution. In order to alleviate resource pressure, Paris mairei can be considered as alternative sources. Here, we report the complete chloroplast genome of Paris mairei. The genome is 162,736 bp in length including a small single-copy region (SSC, 12,908 bp) and a large single-copy region (LSC, 84,286 bp) separated by a pair of inverted repeats (IRs; 32,771 bp). The genome contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 tRNA genes. Among these genes, 16 harboured a single intron, and 2 contained a couple of introns. The overall G + C content of the cpDNA is 37.1%, while the corresponding values of the LSC, SSC, and IR regions are 35.7, 32.1, and 39.9%, respectively. The complete chloroplast genome sequence of Paris mairei will provide a useful resource for the conservation genetics of this species as well as for the phylogenetic studies for the genus Paris.