Complete valorization of lignocellulose with one-step acidified monophasic phenoxyethanol fractionation.

Effective fractionation of lignocelluosic biomass and subsequent valorization of all three major components under mild conditions were achieved. Pretreatment with acidified monophasic phenoxyethanol (EPH) efficiently removed 92.6% lignin and 80% xylan from poplar at 110 ℃ in 60 min, yielding high-value EPH-xyloside, EPH-modified lignin (EPHL), and a solid residue nearly purely composed of carbohydrates. After removing the grafted acetyl groups using 1% NaOH at 50 ℃, the highest enzymatic digestibility reached 92.3%. EPHL could be recovered in high yield and purity with an uncondensed structure, while xylose was converted to EPH-xyloside, a potential precursor in biomedical industries. Additionally, the acidified monophasic EPH solvent could effectively fractionate biomass from species other than hardwood, achieving over 70% delignification from recalcitrant pinewood under the same mild conditions, demonstrating the high potential of monophasic EPH pretreatment.

Comparative phylogenetic analysis of the mediator complex subunit in asparagus bean (Vigna unguiculata ssp. sesquipedialis) and its expression profile under cold stress.

BACKGROUND: The mediator complex subunits (MED) constitutes a multiprotein complex, with each subunit intricately involved in crucial aspects of plant growth, development, and responses to stress. Nevertheless, scant reports pertain to the VunMED gene within the context of asparagus bean (Vigna unguiculata ssp. sesquipedialis). Establishing the identification and exploring the responsiveness of VunMED to cold stress forms a robust foundation for the cultivation of cold-tolerant asparagus bean cultivars. RESULTS: Within this study, a comprehensive genome-wide identification of VunMED genes was executed in the asparagus bean cultivar 'Ningjiang3', resulting in the discovery of 36 distinct VunMED genes. A phylogenetic analysis encompassing 232 MED genes from diverse species, including Arabidopsis, tomatoes, soybeans, mung beans, cowpeas, and asparagus beans, underscored the highly conserved nature of MED gene sequences. Throughout evolutionary processes, each VunMED gene underwent purification and neutral selection, with the exception of VunMED19a. Notably, VunMED9/10b/12/13/17/23 exhibited structural variations discernible across four cowpea species. Divergent patterns of temporal and spatial expression were evident among VunMED genes, with a prominent role attributed to most genes during early fruit development. Additionally, an analysis of promoter cis-acting elements was performed, followed by qRT-PCR assessments on roots, stems, and leaves to gauge relative expression after exposure to cold stress and subsequent recovery. Both treatments induced transcriptional alterations in VunMED genes, with particularly pronounced effects observed in root-based genes following cold stress. Elucidating the interrelationships between subunits involved a preliminary understanding facilitated by correlation and principal component analyses. CONCLUSIONS: This study elucidates the pivotal contribution of VunMED genes to the growth, development, and response to cold stress in asparagus beans. Furthermore, it offers a valuable point of reference regarding the individual roles of MED subunits.

Molecular Regulatory Mechanism of Exogenous Hydrogen Sulfide in Alleviating Low-Temperature Stress in Pepper Seedlings.

Pepper (Capsicum annuum L.) is sensitive to low temperatures, with low-temperature stress affecting its plant growth, yield, and quality. In this study, we analyzed the effects of exogenous hydrogen sulfide (H2S) on pepper seedlings subjected to low-temperature stress. Exogenous H2S increased the content of endogenous H2S and its synthetase activity, enhanced the antioxidant capacity of membrane lipids, and protected the integrity of the membrane system. Exogenous H2S also promoted the Calvin cycle to protect the integrity of photosynthetic organs; enhanced the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and photosynthesis; and reduced the intercellular CO2 concentration (Ci). Moreover, the activities of superoxide dismutase, peroxidase, catalase, and anti-cyclic glutathione (ASA-GSH) oxidase were improved to decompose excess reactive oxygen species (ROS), enhance the oxidative stress and detoxification ability of pepper seedlings, and improve the resistance to low-temperature chilling injury in 'Long Yun2' pepper seedlings. In addition, the H2S scavenger hypotaurine (HT) aggravated the ROS imbalance by reducing the endogenous H2S content, partially eliminating the beneficial effects of H2S on the oxidative stress and antioxidant defense system, indicating that H2S can effectively alleviate the damage of low temperature on pepper seedlings. The results of transcriptome analysis showed that H2S could induce the MAPK-signaling pathway and plant hormone signal transduction; upregulate the expression of transcription factors WRKY22 and PTI6; induce defense genes; and activate the ethylene and gibberellin synthesis receptors ERF1, GDI2, and DELLA, enhancing the resistance to low-temperature chilling injury of pepper seedlings. The plant-pathogen interaction was also significantly enriched, suggesting that exogenous H2S also promotes the expression of genes related to plant-pathogen interaction. The results of this study provide novel insights into the molecular mechanisms and genetic modifications of H2S that mitigate the hypothermic response.

NO and GSH Alleviate the Inhibition of Low-Temperature Stress on Cowpea Seedlings.

Low-temperature stress in early spring seriously affects the growth and development of cowpea seedlings. To study the alleviative effect of the exogenous substances nitric oxide (NO) and glutathione (GSH) on cowpea (Vigna unguiculata (Linn.) Walp.) seedlings under 8 °C low-temperature stress, 200 µmol·L-1 NO and 5 mmol·L-1 GSH were sprayed on cowpea seedlings whose second true leaf was about to unfold to enhance the tolerance of cowpea seedlings to low temperature. Spraying NO and GSH can eliminate excess superoxide radicals (O2-) and hydrogen peroxide (H2O2) to varying degrees, reduce the content of malondialdehyde and relative conductivity, delay the degradation of photosynthetic pigments, increase the content of osmotic regulating substances such as soluble sugar, soluble protein, and proline, and improve the activity of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, dehydroascorbate reductase, and monodehydroascorbate reductase. This study revealed that the mixed use of NO and GSH played an important role in alleviating low temperature stress, and the effect of spraying NO alone was better than that of spraying GSH.

The Effect of B4C Powder on Properties of the WAAM 2319 Al Alloy.

With ER2319 and B4C powder as feedstocks and additives, respectively, a wire arc additive manufacturing (WAAM) system based on double-pulse melting electrode inert gas shielded welding (DP-MIG) was used to fabricate single-pass multilayer 2319 aluminum alloy. The results showed that, compared with additive manufacturing component without B4C, the addition of which can effectively reduce the grain size (from 43 µm to 25 µm) of the tissue in the deposited layer area and improve its mechanical properties (from 231 MPa to 286 MPa). Meanwhile, the mechanical properties are better in the transverse than in the longitudinal direction. Moreover, the strengthening mechanism of B4C on the mechanical properties of aluminum alloy additive manufacturing mainly includes dispersion strengthening from fine and uniform B4C granular reinforcing phases and fine grain strengthening from the grain refinement of B4C. These findings shed light on the B4C induced grain refinement mechanism and improvement of WAAM 2319 Al alloy.

Growth mechanism of glucose-based hydrochar under the effects of acid and temperature regulation.

Improving the tailorability of hydrochar synthesis is an effective way to enhance its performance and utilization efficiency. In this study, the growth rate, morphology, and molecular structure of hydrochar were controlled by regulating the pH and temperature of the hydrothermal carbonization process. Growth process analysis indicates that hydrochar has three growth periods: induction, rapid, and stable growth periods. It is mainly controlled by 5-hydroxymethylfurfural (HMF), which is formed by converting glucose and its transformation products. The regulation of acid can significantly shorten the induction period of hydrochar, even under low-temperature conditions (<180℃), and increase the growth rate of hydrochar. However, the degree of hydrochar adhesion varies: the lower the temperature, the greater the degree of its adhesion. Molecular structural analysis demonstrates that hydrochar mainly consists of furan structural domains and aromatic clusters, and its surface is rich in oxygen-containing functional groups. The degree at which hydrochar was aromatized was improved by increasing the reaction temperature (160-220℃); whereas the regulation of acid reduced it and increased the content of oxygen-containing functional groups on the hydrochar surface. Based on these results, it is proposed that hydrochar formation has five stages and three growth periods with or without acid regulation.

Revealing the relationship between molecular weight of lignin and its color, UV-protecting property.

Lignin has great potential as a natural, green, and sustainable broad-spectrum sunscreen active ingredient. However, the coexistence of dark color and sunscreen properties hinders its application in cosmetics. In this study, we focus on the effects of the molecular weight of lignin on tis UV-protecting property and color in order to prepare lignin-based sunscreen with high performance. A prepared sunscreen containing low molecular weight lignin (F5, <1000 g/mol) exhibits good UV-protecting property (sun protection factor (SPF) = 7.14) and light color advantages (ΔE = 46.2). Moreover, a strong synergistic effect on UV-protecting property exists between low molecular weight lignin and ethylhexyl methoxycinnamate (EHMC), resulting in high SPF of F5@EHMC-based sunscreen (55.56). Additionally, added TiO2 can efficiently mitigate the dark color of lignin-based sunscreens due to prominent covering power of TiO2. Moreover, lignin-based sunscreens have good biocompatibility with HaCaT cells. This work is useful for understanding the mechanism of the UV-protecting property and dark color of lignin, and for designing an efficient and safe lignin-based sunscreen.

Interaction of lignin and xylan in the hydrothermal synthesis of lignocellulose-based carbon quantum dots and their application in in-vivo bioimaging.

The complex interaction of lignin, cellulose, and hemicellulose in the hydrothermal degradation progress of lignocellulose, has led to uncertainty in the hydrothermal synthesis of lignocellulose-based CQDs (LC-CQDs). This makes it difficult to identify the specific formation mechanism of LC-CQDs. To simplify the reaction system and comprehensively describe the formation of LC-CQDs, both lignin and hemicellulose, the main hydrothermal degradation products of lignocellulose, were used as precursor to simulate and explore the synthesis of LC-CQDs at different time intervals (2-12 h). First, different lignin models were employed for preparing CQDs to determine the key lignin structure that govern CQDs formation. G-type lignin-model based CQDs were shown to have higher fluorescence intensity than H- and S-type. Then, G-type lignin model and hemicellulose model (xylan) were used simultaneously hydrothermal to prepare LC-CQDs. The analysis shows that the carbon nucleus preferentially formed by the lignin provides growth sites for small molecules degraded from hemicellulose, which gradually grow around the carbon core over time, thus forming a "sunflower" structure of CQDs. The presence of a lignin model could effectively guide the small molecules toward CQDs formation instead of carbonization. Additionally, the CQDs exhibit good in-vivo imaging performance.

Nanocellulose/two dimensional nanomaterials composites for advanced supercapacitor electrodes.

With the emerging of the problems of environmental pollution and energy crisis, the development of high-efficiency energy storage technology and green renewable energy is imminent. Supercapacitors have drawn great attention in wearable electronics because of their good performance and portability. Electrodes are the key to fabricate high-performance supercapacitors with good electrochemical properties and flexibility. As a biomass based derived material, nanocellulose has potential application prospects in supercapacitor electrode materials due to its biodegradability, high mechanical strength, strong chemical reactivity, and good mechanical flexibility. In this review, the research progress of nanocellulose/two dimensional nanomaterials composites is summarized for supercapacitors in recent years. First, nanocellulose/MXene composites for supercapacitors are reviewed. Then, nanocellulose/graphene composites for supercapacitors are comprehensively elaborated. Finally, we also introduce the current challenges and development potential of nanocellulose/two dimensional nanomaterials composites in supercapacitors.

Enhancing thermal conductivity and toughness of cellulose nanofibril/boron nitride nanosheet composites.

Generally, the thermal conductivity (TC) of composite based on cellulose nanofibrils (CNF) is improved by adding thermal conductive filler, which inevitably leads to the loss of its mechanical properties. In this work, it is the first to simultaneously improve the toughness and TC of CNF/boron nitride nanosheets (BNNS) composite from the perspective of thermal conductive filler addition and CNF crystal change. The hydrophilic-modified BNNSs were successfully prepared by xylose-assisted ball-milling prior to adding into CNF. Compared with that of CNF film (1.34 W/(m·K)), the in-plane TC of CNF/BNNS composite (12.68 W/(m·K)) increased significantly by 846 % with loading 30 % BNNS. Afterwards, both toughness (8.0 MJ·m-3, increased ~250 %) and TC (14.7 W/(m·K), increased ~16 %) of CNF/BNNS composite were further enhanced significantly by mercerization with 12.5 % NaOH solution. The simultaneously improvement of toughness and TC is unprecedented in related studies, which contributes to the effective preparation of thermal management materials.

Utilization of guaiacol-based deep eutectic solvent for achieving a sustainable biorefinery.

This study proposed a renewable deep eutectic solvent (DES) pretreatment using lignin-derived guaiacol as the hydrogen bond donor. The DES showed excellent biomass fractionation efficiency after the incorporation of trace AlCl3 as the reinforcer, which removed 79.1 % lignin while preserving more than 90 % glucan. The pretreated bamboo exhibited 96.2 % glucan enzymatic hydrolysis yield at only 110 °C. The physicochemical properties of the pretreated solids were comprehensively investigated to explain how the DES fractionation overcame the biomass recalcitrance. The regenerated lignin from the DES pretreatment was also analyzed, which revealed that lignin ß-O-4 bond was significantly cleaved. This guaiacol-based DES could greatly contribute to establish a closed-loop biorefinery sequence with high lignin fractionation efficiency and great solvent recyclability.

Competitive effects of glucan's main hydrolysates on biochar formation: A combined experiment and density functional theory analysis.

The complexity of polysaccharide hydrothermal products increases the difficulty of exploring the formation of biochar, limiting the development of biochar. This work clarifies the completive effects of glucan's main hydrolysates on biochar formation from three aspects: experimental, thermodynamic, and kinetic. The products distribution illustrates that 5-HMF, FA, and LA are mainly involved in the formation of biochar. Biochar mainly includes furan ring, ether group, and ester group by the analysis of magic-angle-spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analysis. Combined experiments and density functional theory analysis, the etherification reaction of 5-HMF itself is most likely to occur and is key to form biochar, followed by the esterification of FA with 5-HMF, and then the etherification of 5-HMF and LA. The further verified experiments also manifest these results. This work will develop a foundation for exploring the complex formation mechanism of cellulose-based biochar.

Preparation, Properties, and Application of Lignocellulosic-Based Fluorescent Carbon Dots.

Carbon dots (CDs) are a relatively new type of fluorescent carbon material with excellent performance and widespread application. As the most readily available and widely distributed biomass resource, lignocellulosics are a renewable bioresource with great potential. Research into the preparation of CDs with lignocellulose (LC-CDs) has become the focus of numerous researchers. Compared with other carbon sources, lignocellulose is low cost, rich in structural variety, exhibits excellent biocompatibility,[1] and the structures of CDs prepared by lignin, cellulose, and hemicellulose are similar. This Review summarized research progress in the preparation of CDs from lignocellulosics in recent years and reviewed traditional and new preparation methods, physical and chemical properties, optical properties, and applications of LC-CDs, providing guidance for the formation and improvement of LC-CDs. In addition, the challenges of synthesizing LC-CDs were also highlighted, including the interaction of different lignocellulose components on the formation of LC-CDs and the nucleation and growth mechanism of LC-CDs; from this, current trends and opportunities of LC-CDs were examined, and some research methods for future research were put forward.

Genome and pan-genome assembly of asparagus bean (Vigna unguiculata ssp. sesquipedialis) reveal the genetic basis of cold adaptation.

Asparagus bean (Vigna unguiculata ssp. sesquipedialis) is an important cowpea subspecies. We assembled the genomes of Ningjiang 3 (NJ, 550.31 Mb) and Dubai bean (DB, 564.12 Mb) for comparative genomics analysis. The whole-genome duplication events of DB and NJ occurred at 64.55 and 64.81 Mya, respectively, while the divergence between soybean and Vigna occurred in the Paleogene period. NJ genes underwent positive selection and amplification in response to temperature and abiotic stress. In species-specific gene families, NJ is mainly enriched in response to abiotic stress, while DB is primarily enriched in respiration and photosynthesis. We established the pan-genomes of four accessions (NJ, DB, IT97K-499-35 and Xiabao II) and identified 20,336 (70.5%) core genes present in all the accessions, 6,507 (55.56%) variable genes in two individuals, and 2,004 (6.95%) unique genes. The final pan genome is 616.35 Mb, and the core genome is 399.78 Mb. The variable genes are manifested mainly in stress response functions, ABC transporters, seed storage, and dormancy control. In the pan-genome sequence variation analysis, genes affected by presence/absence variants were enriched in biological processes associated with defense responses, immune system processes, signal transduction, and agronomic traits. The results of the present study provide genetic data that could facilitate efficient asparagus bean genetic improvement, especially in producing cold-adapted asparagus bean.

Fluorescence Enhancement of Lignin-Based Carbon Quantum Dots by Concentration-Dependent and Electron-Donating Substituent Synergy and Their Cell Imaging Applications.

Black liquor is an important pollutant in the pulp industry, but it also has the potential for high-value utilization. In this study, lignin extracted from black liquor was hydrothermally prepared into lignin-based carbon quantum dots (L-CQDs) using a one-pot method. Physicochemical characterization suggested that the L-CQDs exhibited a lamellar core-shell multilayered graphene structure surrounded by oxygen-containing functional groups. The fluorescence intensity of the L-CQDs was strengthened depending on their own concentration dependence and the doping of external groups. The fluorescence intensity of L-CQDs varied between 89.09 and 183.66 under different concentrations, and the most intense fluorescence (183.66) was obtained at 0.1 mg mL-1. At hydroxyl and amino adsorption capacities of 11.08 and 0.98 mmol g-1, the hydroxylated RL-CQDs-5 and aminated NL-CQDs-3 exhibited the highest fluorescence intensities at 689.22 and 605.39, respectively. Moreover, when pristine L-CQDs were sequentially aminated and hydroxylated, the NRL-CQDs' fluorescence intensity reached 1224.92. Cell imaging experiments proved that cells cultivated with NRL-CQDs have brighter fluorescence compared with L-CQDs. The results will render L-CQDs more suitable for practical applications.

Preparation and Application in Water Treatment of Magnetic Biochar.

This paper reviews the preparation of magnetic biochar and its application in wastewater treatment, and briefly discusses the adsorption mechanism of biochar to remove pollutants and the modification methods of biochar. Due to the good physical and chemical properties of biochar, including its rough porous structure, it has been widely used to absorb pollutants from water. Magnetic biochar is commonly prepared by combining biochar with magnetic material. The biochar is endowed with the characteristics of the magnetic material, which could effectively solve the problems of difficult recovery and easy loss of adsorbent in water treatment. Magnetic biochar with high carbon content, large specific surface area, magnetic separation, and other excellent properties, has become a hot research topic in recent years. The preparation methods and application properties of magnetic biochar are reviewed. The future research directions of magnetic biochar are put forward to provide directions for further research and application of magnetic biochar materials.

Xylan and xylose decomposition during hot water pre-extraction: A pH-regulated hydrolysis.

One of the key issues in the development of biofuels using lignocellulosic feedstocks is to increase the yield of fermented sugar, and simultaneously decrease the generation of fermentation inhibitors. Therefore, it is essential to understand the degradation mechanism of xylan during hot-water pretreatment. We analyzed the hydrothermal degradation products of xylan and xylose under different conditions. Results showed that furfural and formic acid formed from xylose reached a maximum value of 32.56 % and 35.14 %, respectively. By increasing the initial pH of the xylan solution, the furfural concentration can be reduced effectively to 2% and the formation of formic acid was preferred under alkaline conditions. On this basis, we proposed a new hydrothermal degradation pathway of xylan in alkaline solution. The in-depth understanding of xlyan degradation during hot water pre-treatment will be beneficial for improving the efficiency of biofuel production.

Effect of endoglucanase and high-pressure homogenization post-treatments on mechanically grinded cellulose nanofibrils and their film performance.

In this study, the effects of mechanical grinding (G) assisted by endoglucanase (E) and high-pressure homogenization (H) post-treated cellulose nanofibrils (CNFs) and its film properties were investigated. Compared to only mechanical grinding, these two post-treatment processes improved the size uniformity of CNFs in width. The crystallinity of GECNFs was increased by 4.3 % and the resulting film exhibited low oxygen permeability rate (6.33 mL/m2·day). Moreover, the combination post-treatments of enzyme and homogenization improved the tensile strength and transparency of CNFs films from 132.31 MPa, 27.52 %- to 177.99 MPa, 61.75 %, respectively. Besides, a composite of acrylic resin ABPE-10 and GEHCNFs film under negative pressure improved the transparency (85.68 %) and water contact angle (104.11°) of film. This work also provides insight on the relationship between the CNFs morphology and their film properties, which can be used to improve the CNFs film performance and promote future applications of CNFs.

Effects of adsorbate molecular space conformation on the adsorption capacity of porous carbon materials: A case study of propylene glycol methyl ether.

In most investigations of adsorption process, the effects of adsorbate properties on adsorption capacity were often not obtain enough attention, compared with the properties of adsorbent. Apart from the polarity, and the boiling point of adsorbate, the molecular space conformation is also play an important role in its adsorption behavior on porous materials. In this work, two series of orientation-designed activated carbon were used to study the microscopic adsorption behavior of amphiphilic propylene glycol methyl ether (PM) gas. The spatial conformation of the PM molecule was found to have a strong effect on the adsorption of PM on activated carbon and caused two major adsorption behaviors, "propensity" and "directionality". The PM molecule, as well as other oxygenated VOCs, tended to be adsorbed on areas of activated carbon with similar polarity, which caused its adsorption "propensity". However, the cross-sectional area (55.95 Å2) of the hydrophilic hydroxy groups on a PM molecule is much larger than that of the hydrophobic methoxy groups (29.46 Å2), which leads to the adsorption "directionality", such that the amount of PM adsorption on activated carbon was affected by whether PM molecules were adsorbed by their hydrophilic hydroxy groups or hydrophobic methoxy groups over the same adsorption area. Additionally, a predictive model based on the properties of activated carbon and the PM molecule was proposed and further verified.

A Facile and Green Combined Strategy for Improving Photocatalytic Activity of Carbon Nitride.

We first report an efficient combined strategy that simultaneously integrates copolymerization, doping, and molecular self-assembly for the development of carbon-doping petal-like carbon nitride photocatalysts using melamine (MA), cyanuric acid (CA), and 2,4,6-triaminopyrimidine (TAP) as the starting precursors and water as the only green solvent. The morphology, textural, optical, and electronic properties of carbon nitride could be engineered by rationally manipulating the doping content of TAP. In the process of molecular self-assembly, TAP can insert the aggregate edge easily according to the results of density functional theory (DFT) calculations. The edge-termination effect of TAP made it easier for the modified carbon nitride materials to form petal-like nanosheets with porous structures and large BET surface areas. In addition, the incorporation of TAP also contributed to tuning the electronic band structures of carbon nitrides and enhancing the separation efficiency of photogenerated carriers. The as-prepared materials exhibited excellent photocatalytic activities in the degradation of tetracycline hydrochloride (TC-HCl) and rhodamine B (RhB). This work may not only offer universally powerful and stable photocatalysts for applications but also develop a new combined strategy to fabricate efficient photocatalysts in a facile and green way.