Enhancing cellulose hydrolysis via cellulase immobilization on zeolitic imidazolate frameworks using physical adsorption.

This study investigates the immobilization of cellulase on zeolitic imidazolate frameworks (ZIFs) by physical adsorption, specifically the ZIF-8-NH2 and Fe3O4@ZIF-8-NH2, to enhance enzymatic hydrolysis efficiency. The immobilization process was thoroughly analyzed, including optimization of conditions and characterization of ZIF carriers and immobilized enzymes. The impacts on the catalytic activity of cellulase under various temperatures, pH levels, and storage conditions were examined. Additionally, the reusability of the immobilized enzyme was assessed. Results showed the cellulase immobilized on Fe3O4@ZIF-8-NH2 exhibited a high loading capacity of 339.64 mg/g, surpassing previous studies. Its relative enzymatic activity was found to be 71.39%. Additionally, this immobilized enzyme system demonstrates robust reusability, retaining 68.42% of its initial activity even after 10 cycles. These findings underscore the potential of Fe3O4@ZIF-8-NH2 as a highly efficient platform for cellulase immobilization, with promising implications for lignocellulosic biorefinery.

Current Status of Cognition and Clinical Practice of Refractory Cancer Pain in Shanghai: A Questionnaire Survey.

Purpose: This study aimed to assess the current status of clinical practice of refractory cancer pain (RCP) among a sample of physicians specializing in cancer pain management in Shanghai. Methods: From 2019 to 2021, a questionnaire survey was conducted among physicians engaged in diagnosis and treatment of cancer pain through the questionnaire WJX network platform in Shanghai, China. Results: A total of 238 responses participated in the survey. This survey reports physicians' understanding and incidence rate of breakthrough cancer pain (BTCP). The choice of analgesics and satisfaction of analgesic effect were investigated. We also investigated doctors' knowledge of the diagnostic criteria for RCP and their tendency to choose analgesics. Oral immediate-release morphine and intravenous or subcutaneous morphine injection have been the common treatment approach for transient cancer pain exacerbations. The main barriers to pain management are lack of standardized treatment methods for RCP, lack of knowledge related to RCP, and single drug dosage form. Doctors believe the most necessary measures to improve the current situation of poor cancer pain control include improving medical staff's understanding and treatment techniques for RCP, updating treatment techniques and methods, and improving the configuration of drug types in medical institutions. Clinicians expect to improve understanding and treatment techniques through systematic training. Conclusion: Despite multiple available analgesic measures, the treatment of RCP remains challenging. Improving the understanding of medical staff towards RCP, improving treatment techniques, and increasing the accessibility of multiple drug types are important ways to improve the satisfaction of cancer pain management in the future.

Urinary biomarkers of drinking-water disinfection byproducts in relation to diminished ovarian reserve risk: A case-control study from the TREE cohort.

BACKGROUND: Disinfection byproducts (DBPs) as ovarian toxicants have been documented in toxicological studies. However, no human studies have explored the effects of exposure to DBPs on diminished ovarian reserve (DOR). OBJECTIVE: To assess whether urinary biomarkers of exposure to drinking-water DBPs were associated with DOR risk. METHODS: A total of 311 women undergoing assisted reproductive technology were diagnosed with DOR in the Tongji Reproductive and Environmental (TREE) cohort from December 2018 to August 2021. The cases were matched to the controls with normal ovarian reserve function by age in a ratio of 1:1. Urinary trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were quantified as biomarkers of drinking-water DBP exposures. The conditional logistic regression and restricted cubic spline (RCS) were used to explore urinary biomarkers of drinking-water DBP exposures in associations with the risk of DOR. RESULTS: Elevated urinary DCAA levels were associated with higher DOR risk [adjusted odds ratio (OR) = 1.87; 95 % confidence interval (CI): 1.16, 3.03 for the highest vs. lowest quartiles; P for trend = 0.016]. The association was confirmed in the RCS model, with a linear dose-response curve (P for overall association = 0.029 and P for non-linear association = 0.708). The subgroup analysis by age and body mass index (BMI) showed that urinary DCAA in association with DOR risk was observed among women ≥35 years old and leaner women (BMI < 24 kg/m2), but the group differences were not statistically significant. Moreover, a U-shaped dose-response curve between urinary TCAA and DOR risk was estimated in the RCS model (P for overall association = 0.011 and P for non-linear association = 0.004). CONCLUSIONS: Exposure to drinking-water DBPs may contribute to the risk of DOR among women undergoing assisted reproductive technology.

Cellulase immobilization to enhance enzymatic hydrolysis of lignocellulosic biomass: An all-inclusive review.

Cellulase-mediated lignocellulosic biorefinery plays a crucial role in the production of high-value biofuels and chemicals, with enzymatic hydrolysis being an essential component. The advent of cellulase immobilization has revolutionized this process, significantly enhancing the efficiency, stability, and reusability of cellulase enzymes. This review offers a thorough analysis of the fundamental principles underlying immobilization, encompassing various immobilization approaches such as physical adsorption, covalent binding, entrapment, and cross-linking. Furthermore, it explores a diverse range of carrier materials, including inorganic, organic, and hybrid/composite materials. The review also focuses on emerging approaches like multi-enzyme co-immobilization, oriented immobilization, immobilized enzyme microreactors, and enzyme engineering for immobilization. Additionally, it delves into novel carrier technologies like 3D printing carriers, stimuli-responsive carriers, artificial cellulosomes, and biomimetic carriers. Moreover, the review addresses recent obstacles in cellulase immobilization, including molecular-level immobilization mechanism, diffusion limitations, loss of cellulase activity, cellulase leaching, and considerations of cost-effectiveness and scalability. The knowledge derived from this review is anticipated to catalyze the evolution of more efficient and sustainable biocatalytic systems for lignocellulosic biomass conversion, representing the current state-of-the-art in cellulase immobilization techniques.

Sustainable production of dopamine hydrochloride from softwood lignin.

Dopamine is not only a widely used commodity pharmaceutical for treating neurological diseases but also a highly attractive base for advanced carbon materials. Lignin, the waste from the lignocellulosic biomass industry, is the richest source of renewable aromatics on earth. Efficient production of dopamine direct from lignin is a highly desirable target but extremely challenging. Here, we report an innovative strategy for the sustainable production of dopamine hydrochloride from softwood lignin with a mass yield of 6.4 wt.%. Significantly, the solid dopamine hydrochloride is obtained by a simple filtration process in purity of 98.0%, which avoids the tedious separation and purification steps. The approach begins with the acid-catalyzed depolymerization, followed by deprotection, hydrogen-borrowing amination, and hydrolysis of methoxy group, transforming lignin into dopamine hydrochloride. The technical economic analysis predicts that this process is an economically competitive production process. This study fulfills the unexplored potential of dopamine hydrochloride synthesis from lignin.

Aberrant KAT2A accumulations render TRIM22-low melanoma sensitive to Notch1 inhibitors via epigenetic reprogramming.

BACKGROUND: Aberrant ubiquitin-proteasome system (UPS) triggers various disorders of biological events and contributes to progression of tumorigenesis. The tripartite motif containing 22 (TRIM22) was demonstrated to participate in the progression of multiple malignancies. Nevertheless, the role of TRIM22 in melanoma is still indefinite. This project aims to investigate the biological function of TRIM22 in melanoma and provide novel therapeutical targets. METHODS: Bioinformatic algorithms were used to investigate prognostic significance of TRIM22. The in vitro or in vivo assays were used to explore the functions of TRIM22 in melanoma. The Co-Immunoprecipitation (Co-IP) and in vivo ubiquitination assays were used to assess regulations of TRIM22 on lysine acetyltransferase 2 A (KAT2A). The Chromatin immunoprecipitation (ChIP) assays and luciferase reporter assay were utilized to explore epigenetic regulations of KAT2A on Notch1. RESULTS: Here, we utilized the bioinformatic methods to confirm that TRIM22 is decreased in melanoma than normal tissues. Patients with low TRIM22 levels had shorter survival months than those with high TRIM22 levels. Targeting TRIM22 favors melanoma cell migration, proliferation, and tumor development in vitro and in vivo. Mechanistically, TRIM22 interacts with KAT2A and promotes its degradation in a ubiquitination-dependent manner. Melanoma cells with TRIM22 deficiency depended on KAT2A to enhance malignant progression, including proliferation, migration, and in vivo growth. KEGG analysis determined the positive correlation between KAT2A and Notch signaling. Chromatin Immunoprecipitation (ChIP) assays implicated that KAT2A directly binds to the promoter region of Notch1 and mediates the enrichment of H3K9ac modification. KAT2A activates Notch1 transcriptional levels and sustains the stemness feature of melanoma cells. Nocth1 inhibitor (IMR-1) effectively suppresses the growth of TRIM22low melanoma in vitro and in vivo but fails to inhibit TRIM22high melanoma. CONCLUSION: Together, our study illustrates the mechanism by which the TRIM22-KAT2A-Notch1 axis promotes melanoma progression, and demonstrates that KAT2A/Nocth1 confers an epigenetic vulnerability in TRIM22low melanoma.

Construction of oxygen vacancy-rich ZnO@carbon nanofiber aerogels as a free-standing anode for superior lithium storage.

The development of next-generation high-capacity freestanding materials as electrodes in lithium-ion batteries (LIBs) has significant potential. Here, oxygen vacancy-rich ZnO (Ov-ZnO) deposited on carbonized bacterial cellulose (CBC) aerogels is developed via in-situ uniformly growing ZIF-8-NH2 particles on CBC aerogels, followed by the hydrazine reduction and pyrolysis. The CBC serves as a free-standing skeleton to disperse and support ZIF-8-NH2 derived ZnO while the introduction of oxygen vacancies can effectively promote the internal ion/electron transfer. As a result, the obtained free-standing aerogels (Ov-ZnO@CBC) displays a reversible capacity of 710 mAh g-1 at 1 A g-1 after 1000 cycles, which is superior to ZnO@CBC without hydrazine reduction treatment. Furthermore, the assembled Li free-standing full cell using the Ov-ZnO@CBC composite as the anode and BC@LiFePO4 (BC@LFP) as the cathode exhibits an outstanding cycling performance of 150 mAh g-1 after 100 cycles at 0.1 A g-1, displaying satisfactory lithium-ion storage capability. It is noteworthy that both Ov-ZnO@CBC and BC@LFP are obtained in the form of a free-standing aerogel. This work offers a strategy to prepare high-capacity and long-cycle self-supporting aerogel-based electrodes for flexible LIBs.

Pyrolysis Kinetics of Lignin-Based Flame Retardants Containing MOFs Structure for Epoxy Resins.

This study describes the preparation of a lignin-based expandable flame retardant (Lignin-N-DOPO) using grafting melamine and covering 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) using the Mannich reaction. Then, through in situ growth, a metal-organic framework (MOF) HKUST-1 (e.g., Cu3(BTC)2, BTC = benzene-1,3,5-tricarboxylate)/lignin-based expandable flame retardant (F-lignin@HKUST-1) was created. Before that, lignin epoxy resin containing phosphorus (P) and nitrogen (N) components had been created by combining epoxy resin (EP) with F-lignin@HKUST-1. Thermogravimetric analysis was used to examine the thermal characteristics of epoxy resin (EP) composite. The findings indicate that the thermal stability of EP is significantly affected by the presence of F-lignin@HKUST-1. Last but not least, the activation energy (E) of EP/15% F-lignin@HKUST-1 was examined using four different techniques, including the Kissinger-SY iteration method, the Ozawa-SY iteration method, the Lee-Beck approximation-iteration method, and the Gorbatchev approximation-iteration method. It was discovered that the activation energy was significantly higher than that of lignin. Higher activation energy suggests that F-lignin@HKUST-1 pyrolysis requires more energy from the environment, which will be significant about the application of lignin-based flame retardants.

Kinetic modeling of xylonic acid production by Gluconobacter oxydans: effects of hydrodynamic conditions.

In this study, the synthesis of xylonic acid from xylose by Gluconobacter oxydans NL71 has been investigated. According to the relationship between oxygen transfer rate and oxygen uptake rate, three different kinetic models of product formation were established and the nonlinear fitting was carried out. The results showed that G. oxydans has critical dissolved oxygen under different strain concentrations, and the relationship between respiration intensity and dissolved oxygen conformed to the Monod equation [Formula: see text]. The maximum reaction rate per unit cell mass and the theoretical maximum specific productivity of G. oxydans obtained by the kinetic model are 0.042 mol/L/h and 6.97 g/gx/h, respectively. These results will assist in determining the best balance between the airflow rate and cell concentration in the reaction and improve the production efficiency of xylonic acid.

FOUR LIPS plays a role in meristemoid-to-GMC fate transition during stomatal development in Arabidopsis.

Meristemoids, which are stomatal precursor cells, exhibit self-renewal and differentiation abilities. However, the only known core factor associated with meristemoid division termination and fate transition is the heterodimer formed by the basic helix-loop-helix proteins MUTE and SCREAMs (SCRMs). FOUR LIPS (FLP), a well-known transcription factor that restricts guard mother cell (GMC) division, is a direct target of MUTE. Whether FLP involves in meristemoid differentiation is unknown. Through sensitized genetic screening of flp-1, we identified a mute-like (mutl) mutant with arrested meristemoids. The mutant carried a novel allele of the MUTE locus, i.e., mute-4. Intriguingly, mute-4 is a hypomorphic allele that exhibits wild-type appearance with slightly delayed meristemoid-to-GMC transition, whereas it renders an unexpected mutl epidermis with most meristemoids arrested and very few stomata when combined with flp (flp mute-4), suggesting that FLP is a positive regulator during this transition process. Consistently, the expression of FLP increased during GMC commitment, and the number of cells at this stage was markedly increased in flp. flp scrm double mutants produced arrested meristemoids similar to mute, and FLP was able to interact physically with SCRM. Taken together, our results demonstrate that FLP functions together with MUTE and SCRMs to direct meristemoid-to-GMC fate transition.

Electroacupuncture alleviates pain after total knee arthroplasty through regulating neuroplasticity: A resting-state functional magnetic resonance imaging study.

INTRODUCTION: We aimed to evaluate the efficacy of electroacupuncture in relieving acute pain after total knee arthroplasty (TKA) and related mechanism. METHODS: In this randomized, single-blind, and sham-acupuncture controlled study. Forty patients with postoperative acute pain were recruited and randomly divided electroacupuncture group (n = 20) and sham-acupuncture group (n = 20) from November 2020 to October 2021. All patients received electroacupuncture or sham-acupuncture for 5 days after TKA. Their brain regions were scanned with resting-state functional magnetic resonance imaging before and after intervention. Pain was scaled. Another 40 matched healthy controls underwent scanning once. The amplitude of low-frequency fluctuation (ALFF) values was compared. Pearson's correlation analysis was utilized to explore the correlation of ALFF with clinical variables in patients after intervention. RESULTS: Compared with the HCs, patients with acute pain following TKA had significantly decreased ALFF value in right middle frontal gyrus, right supplementary motor area, bilateral precuneus, right calcarine fissure and surrounding cortex, and left triangular part of inferior frontal gyrus (false discovery rate corrected p < .05). Patients had higher ALFF value in bilateral precuneus, right cuneus, right angular gyrus, bilateral middle occipital gyrus, and left middle temporal gyrus after electroacupuncture (AlphaSim corrected p < .01). Correlation analysis revealed that the change (postoperative day 7 to postoperative day 3) of ALFF in bilateral precuneus were negatively correlated with the change of NRS scores (r = -0.706; p = .002; 95% CI = -0.890 to -0.323) in EA group. CONCLUSIONS: The functional activities of related brain regions decreased in patients with acute pain after TKA. The enhancement of the functional activity of precuneus may be the neurobiological mechanism of electroacupuncture in treating pain following TKA.

All-Trans Retinoic Acid Promotes M2 Macrophage Polarization in Vitro by Activating the p38MAPK/STAT6 Signaling Pathway.

BACKGROUND: M2-type macrophages are inflammation-suppressing cells that are differentiated after induction by cytokines such as IL-4 or IL-13, which play an important regulatory role in inflammation and influence the regression of inflammation-related diseases. All-trans retinoic acid (ATRA) has an important role in suppressing immune-mediated inflammatory responses but the effect and underlying mechanism of ATRA on the polarization of M2 macrophages remains unclear. METHODS: Macrophages were isolated from peritoneal wash fluid, and IL-4 (20 ng/mL) was used to construct a m2-type macrophage polarization model. The model was incubated with different concentrations of ATRA (15 µg/ml, 30 µg/ml, 45 µg/ml) for 24 h, and pretreated macrophages with p38MAPKα inhibitor SB202190 (20 µM). MTT, Trypan blue staining, Annexin V-PE/7-AAD staining, flow cytometry, real-time PCR and western blotting were used to investigate the effect and mechanism of ATRA on the polarization of M2 macrophages. RESULTS: Compared with the IL-4 group, the proportion of F4/80+CD206+ M2-type macrophages was significantly higher in the ATRA group (P < 0.01). mRNA and protein expression levels of Arg-1, IL-10 and TGF-ß1 were as significantly higher (P < 0.01) in the ATRA group as phosphorylation levels of STAT6 and p38MAPK (P < 0.01). After pretreatment with the addition of the inhibitor SB202190, M2-type macrophages proportion and their associated factors expression were significantly (P < 0.01) reduced, as compared with those in the ATRA group, but they were comparable (P > 0.05) with the IL-4 group. CONCLUSION: The combination of ATRA and IL-4 activated the p38MAPK/STAT6-signaling pathway to promote polarization of M2 macrophages.

A review on lignin-based epoxy resins: Lignin effects on their synthesis and properties.

Lignin can be used as a sustainable alternative to bisphenol A (BPA) to prepared lignin-based epoxy resins. Lignin effects including molecular weight, phenolic content, G/S unit ratio and flexible/rigid linkage ratio on epoxy synthesis and performance were summarized comprehensively. The incorporation of lignin with a higher molecular weight would lead to the higher rigidity of epoxy crosslinking network. Higher contents of ether bonds in lignin would provide higher structural flexibility of lignin incorporated epoxy thermosets. Lignin with higher contents of phenolic hydroxyls was more beneficial for improving the reactivity of its epoxy products after glycidylation. Due to the excellent charring capacity of lignin, higher contents of residue char can be produced at higher additions of lignin at high temperatures, while the loss of crosslinking density caused by the increasing lignin addition (especially for the macromolecular lignin) would deteriorate the thermal stability of their thermosets. Several applications of lignin-based epoxy resins were also mentioned based on their mechanical, thermal and chemical properties, such as coatings (with anticorrosion and UV-blocking), adhesives (with highly crosslinking network, excellent mechanical, and thermal properties) and flame retardants (with high charring capability).

Oxygen mass transfer enhancement by activated carbon particles in xylose fermentation media.

In this work, the effect of activated carbon particles on the production of xylonic acid from xylose by Gluconobacter oxydans in a stirred tank bioreactor was investigated. The enhancement of the oxygen transfer coefficient by activated carbon particles was experimentally evaluated under different solids volume fractions, agitation and aeration rates conditions. The experimental conditions optimized by response surface methodology (agitation speed 800 rpm, aeration rate 7 L min-1, and activated carbon 0.002%) showed a maximum oxygen transfer coefficient of 520.7 h-1, 40.4% higher than the control runs without activated carbon particles. Under the maximum oxygen transfer coefficient condition, the xylonic acid titer reached 108.2 g/L with a volumetric productivity of 13.53 g L-1 h-1 and a specific productivity of 6.52 g/gx/h. In conclusion, the addition of activated carbon particles effectively enhanced the oxygen mass transfer rate. These results demonstrate that activated carbon particles enhanced cultivation for xylonic acid production an inexpensive and attractive alternative.

Progress on quantum dot photocatalysts for biomass valorization.

Biomass with abundant reproducible carbon resource holds great promise as an intriguing substitute for fossil fuels in the manufacture of high-value-added chemicals and fuels. Photocatalytic biomass valorization using inexhaustible solar energy enables to accurately break desired chemical bonds or selectively functionalize particular groups, thus emerging as an extremely creative and low carbon cost strategy for relieving the dilemma of the global energy. Quantum dots (QDs) are an outstandingly dynamic class of semiconductor photocatalysts because of their unique properties, which have achieved significant successes in various photocatalytic applications including biomass valorization. In this review, the current development rational design for QDs photocatalytic biomass valorization effectively is highlighted, focusing on the principles of tuning their particle size, structure, and surface properties, with special emphasis on the effect of the ligands for selectively broken chemical bonds (C─O, C─C) of biomass. Finally, the present issues and possibilities within that exciting field are described.

A review on lignin pyrolysis: pyrolytic behavior, mechanism, and relevant upgrading for improving process efficiency.

Lignin is a promising alternative to traditional fossil resources for producing biofuels due to its aromaticity and renewability. Pyrolysis is an efficient technology to convert lignin to valuable chemicals, which is beneficial for improving lignin valorization. In this review, pyrolytic behaviors of various lignin were included, as well as the pyrolytic mechanism consisting of initial, primary, and charring stages were also introduced. Several parallel reactions, such as demethoxylation, demethylation, decarboxylation, and decarbonylation of lignin side chains to form light gases, major lignin structure decomposition to generate phenolic compounds, and polymerization of active lignin intermediates to yield char, can be observed through the whole pyrolysis process. Several parameters, such as pyrolytic temperature, time, lignin type, and functional groups (hydroxyl, methoxy), were also investigated to figure out their effects on lignin pyrolysis. On the other hand, zeolite-driven lignin catalytic pyrolysis and lignin co-pyrolysis with other hydrogen-rich co-feedings were also introduced for improving process efficiency to produce more aromatic hydrocarbons (AHs). During the pyrolysis process, phenolic compounds and/or AHs can be produced, showing promising applications in biochemical intermediates and biofuel additives. Finally, some challenges and future perspectives for lignin pyrolysis have been discussed.

Bulky oxadithiolate-bridged [FeFe]­hydrogenase mimics [Fe2(µ-R2odt)(CO)4(κ2-diphosphine)] (R = Ph and H) with chelating diphosphines.

In order to develop an attractive generation of bulky oxadithiolate-bridged [FeFe]­hydrogenase mimics with chelating diphosphines, two new series of asymmetrically diphosphine-substituted diiron model complexes [Fe2(µ-R2odt)(CO)4(κ2-diphosphine)] (3-5) with bulky Ph2odt bridge and their reference counterparts (6-8) with common odt bridge were obtained from the Me3NO-assisted substitutions of diiron hexacarbonyl precursors [Fe2(µ-R2odt)(CO)6] (R2odt = (SCHR)2O, R = Ph (1) and H (2)) with different diphosphines such as (Ph2P)2NBn (labelled PNBnP, Bn = benzyl), (Ph2PCH2)2NBn (PCNBnCP), and (Ph2PCH2)2CH2 (DPPP)), respectively. All the as-prepared complexes have been characterized by elemental analysis, IR plus NMR spectroscopies, and particularly by X-ray crystallography for 3-8. It is interesting to note that complexes 3 and 6 chelating by small bite-angle PNBnP diphosphine have the favorable dibasal isomer whereas analogues 4, 5 and 7, 8 chelating by flexible backbone PCNBnCP or DPPP ligands possess the main apical-basal isomer in solution or in the solid state. Further, the electrochemical properties of two pairs of representative complexes 3, 6 and 5, 8 are explored and compared by cyclic voltammetry (CV) in the absence and presence of trifluoroacetic acid (CF3CO2H) as proton source, indicating that the complete protonations of 3, 6 and 5, 8 with higher concentration of CF3CO2H lead to two new catalytic waves for the electrocatalytic proton reduction to hydrogen (H2).

A review on lignin antioxidants: Their sources, isolations, antioxidant activities and various applications.

Lignin, a biopolymer obtained from agricultural/forestry residues or paper pulping wastewater, is rich in aromatic structure, which is central to its adoption as a candidate to natural antioxidants. Through insight into its structural features from biomass, different functional groups would influence lignin antioxidant activity, wherein phenolic content is the most important factor, hence massive studies have focused on its improvement via different pretreatments and post-processing methods. Besides, lignin nanoparticles and chemical modifications are also efficient methods to improve antioxidant activity via increasing free content and decreasing bond dissociation enthalpy of phenolic hydroxyl. Lignin samples exhibit comparable radicals scavenging ability to commercial ones, showing their potential as renewable alternatives of synthesized antioxidants. Besides, their applications have also been discussed, which demonstrates lignin potential as an inexpensive antioxidant additive and consequent improvements on multiple functionalities. This review is dedicated to summarize lignin antioxidants extracted from biomass resources, methods to improve their antioxidant activity and their applications, which is beneficial for realizing lignin valorization.

Fabrication of a bi-hydroxyl-bi-DOPO compound with excellent quenching and charring capacities for lignin-based epoxy resin.

In this study, lignin-based epoxy resins (EP) were fabricated using lignin, phenol and glyoxal as crosslinking reagents. For improving the flame retardancy, a bi-DOPO compound with bi-hydroxyl structure was successfully synthesized, containing excellent quenching and charring capacities. Good pyrolysis behaviors of as-synthesized flame retardant resulted in significant quenching effect via structure decomposition to release PO and PO2 free radicals for capturing reactive H and OH radicals produced from epoxy combustion. With addition of 0.18 wt% phosphorus, epoxy composite (10% LPG-ER-4) passed V-0 rating with high limited oxygen index (LOI) value of 35.2%. Cone calorimeter tests showed that heat release (including heat release rate (HRR) and total heat release (THR)) from combustion was reduced with assistance of flame retardant. Char residue analyses illustrated that bi-hydroxyl structure in DOPO-based flame retardant benefited the formation of char layer with higher compactness and integrity to serve as a protective shell of interior epoxy matrix. Furthermore, exterior pore size of char residue was narrowed or blocked to avoid the release of heat and volatiles generated from combustion. This study provided a feasible method to improve flame retardancy of lignin-based EP and proposed flame-retardant mechanism both in gaseous and solid phases.

Selective Catalytic Transfer Hydrogenation of Lignin to Alkyl Guaiacols Over NiMo/Al-MCM-41.

Efficient deoxygenation of lignin-derived bio-oils is central to their adoption as precursors to sustainable liquid fuels in place of current fossil resources. In-situ catalytic transfer hydrogenation (CTH), using isopropanol and formic acid as solvent and in-situ hydrogen sources, was demonstrated over metal-doped and promoted MCM-41 for the depolymerization of oxygen-rich (35.85 wt%) lignin from Chinese fir sawdust (termed O-lignin). A NiMo/Al-MCM-41 catalyst conferred an optimal lignin-derived oil yield of 61.6 wt% with a comparatively low molecular weight (Mw =542 g mol-1 , Mn =290 g mol-1 ) and H/C ratio of 1.39. High selectivity to alkyl guaiacols was attributed to efficient in-situ hydrogen transfer from isopropanol/formic acid donors, and a synergy between surface acid sites in the Al-doped MCM-41 support and reducible Ni/Mo species, which improved the chemical stability and quality of the resulting lignin-derived bio-oils.