Aromatic Alcohol-Based pH-Sensitive Chromophore with a Unique Near-Infrared Dual-Band Solvatochromic Property and Its Application as a Ratiometric Fluorescent Sensor for G-Quadruplexes.

Solvatochromes have gained great attention because of their unique roles in monitoring biomolecular location, interaction, and dynamics. Particularly, solvatochromes presenting both red-shifting excitation and dual-band switchable emission are in great demand yet significantly difficult to come true. In this article, we disclose an aromatic alcohol-based pH-sensitive chromophore NIR-HBT that not only presents red-shifting excitation and solvent-dependent dual-band emission but also shows high photostability and excellent brightness. To the best of our knowledge, this is the first solvatochrome to simultaneously display these optical properties. Especially, in contrast to the reported dual-band solvatochromes whose solvatochromism is achieved by affecting their excited state behaviors, the solvatochromism of NIR-HBT is realized by modulating its ground state proton dissociation, which is a new solvatochromic mechanism that has not been reported. Furthermore, based on the dual-band solvatochromism of NIR-HBT and its intrinsic binding ability to GQs, near-infrared ratiometric detection of GQs is achieved. These results indicate that NIR-HBT is an attractive solvatochrome that can be used to develop near-infrared ratiometric biosensors for biological research. More broadly, the discovered solvatochromic mechanism can also open new horizons for exploring the solvatochrome.

Photosynthetic mechanism of maize yield under fluctuating light environments in the field.

The photosynthetic mechanism of crop yields in fluctuating light environments in the field remains controversial. To further elucidate this mechanism, we conducted field and simulation experiments using maize (Zea mays) plants. Increased planting density enhanced the light fluctuation frequency and reduced the duration of daily high light, as well as the light-saturated photosynthetic rate, biomass, and yield per plant. Further analysis confirmed a highly significant positive correlation between biomass and yield per plant and the duration of photosynthesis related to daily high light. The simulation experiment indicated that the light-saturated photosynthetic rate of maize leaves decreased gradually and considerably when shortening the daily duration of high light. Under an identical duration of high light exposure, increasing the fluctuation frequency decreased the light-saturated photosynthetic rate slightly. Proteomic data also demonstrated that photosynthesis was mainly affected by the duration of high light and not by the light fluctuation frequency. Consequently, the current study proposes that an appropriate duration of daily high light under fluctuating light environments is the key factor for greatly improving photosynthesis. This is a promising mechanism by which the photosynthetic productivity and yield of maize can be enhanced under complex light environments in the field.

Photonic Möbius topological insulator from projective symmetry in multiorbital waveguides.

The gauge fields dramatically alter the algebraic structure of spatial symmetries and make them projectively represented, giving rise to novel topological phases. Here, we propose a photonic Möbius topological insulator enabled by projective translation symmetry in multiorbital waveguide arrays, where the artificial π gauge flux is aroused by the inter-orbital coupling between the first (s) and third (d) order modes. In the presence of π flux, the two translation symmetries of rectangular lattices anti-commute with each other. By tuning the spatial spacing between two waveguides to break the translation symmetry, a topological insulator is created with two Möbius twisted edge bands appearing in the bandgap and featuring 4π periodicity. Importantly, the Möbius twists are accompanied by discrete diffraction in beam propagation, which exhibit directional transport by tuning the initial phase of the beam envelope according to the eigenvalues of translation operators. This work manifests the significance of gauge fields in topology and provides an efficient approach to steering the direction of beam transmission.

The Extraction and Characterization of Pseudorange Multipath Based on BDS-3 Multi-Frequency Observations.

Global Navigation Satellite System (GNSS) observations are subject to various errors during their propagation process. A reasonable correction of these errors can improve the positioning, navigation, and timing (PNT) service capability. The impact of multipaths on pseudorange observations can reach a decimeters or even meters level. However, their mechanism is complex and there is currently no universally accepted high-precision correction model. The correlation between the pseudorange multipaths (MP) of BDS-2 satellites and satellite elevation has been confirmed, while there have been fewer analyses of the MP characteristics for different frequencies of BDS-3 satellites. The broadcasting of multi-frequency observations in BDS-3 should theoretically make the extracted MP more accurate compared to traditional methods. Based on this, in this contribution, a multi-frequency MP extraction algorithm based on the least squares principle is proposed, which can simultaneously eliminate the influence of higher-order ionospheric delay. The analytical expression for only eliminating first-order ionospheric delay is successfully derived. Subsequently, the characteristics of the MPs extracted from different frequency combinations and the impact of combination noise on the extraction accuracy are discussed. The influence of second-order ionospheric delay on the MPs for each frequency under different combination noises, as well as the periodic behavior exhibited in long-term observations of the BDS-3 medium earth orbit (MEO) and inclined geosynchronous orbit (IGSO) satellites, are also analyzed. Finally, the correlations between the MPs of each frequency of BDS satellite and elevation are quantitatively analyzed based on observations from 35 stations. Overall, this work has positive implications for the study of the MP characteristics of BDS-3 and subsequent modeling efforts.

Effects of germline DHFR and FPGS variants on methotrexate metabolism and relapse of leukemia.

Methotrexate (MTX) during maintenance therapy is essential for curing acute lymphoblastic leukemia (ALL), but dosing strategies aiming at adequate treatment intensity are challenged by interindividual differences in drug disposition. To evaluate genetic factors associated with MTX metabolism, we performed a genome-wide association study in 447 ALL cases from the Nordic Society for Pediatric Haematology and Oncology ALL2008 study, validating results in an independent set of 196 patients. The intergenic single-nucleotide polymorphism rs1382539, located in a regulatory element of DHFR, was associated with increased levels of short-chain MTX polyglutamates (P = 1.1 × 10-8) related to suppression of enhancer activity, whereas rs35789560 in FPGS (p.R466C, P = 5.6 × 10-9) was associated with decreased levels of long-chain MTX polyglutamates through reduced catalytic activity. Furthermore, the FPGS variant was linked with increased relapse risk (P = .044). These findings show a genetic basis for interpatient variability in MTX response and could be used to improve future dosing algorithms.

Fabrication of a Carbonized Cellulose Nanofibrils/Ti3C2Tx MXene/g-C3N4 Heterojunction for Visible-Light-Driven Photocatalysis.

Photocatalytic degrading pollutants driven by visible-light irradiation has attracted tremendous attention. One strategy of preparing carbonized cellulose nanofibrils/Ti3C2Tx MXene/g-C3N4 (CMCN) as a photocatalyst was developed. The as-prepared CMCN was comprehensively characterized in terms of the chemical composition, chemical and crystal structure, morphology, and photoelectrochemical properties. The CMCN was explored as a photocatalyst and exhibited good photocatalytic performance in degrading MB (96.5%), RhB (95.4%), and TC (86.5%) under visible-light conditions. In addition, the CMCN as a photocatalyst exhibited good reusability and stability. It is found that the incorporation of cellulose nanofibrils provided a high carbon content, a high porosity, and a large specific surface area, enhanced the electron transfer, improved the photocatalytic performance, and ensured a semiconductor with a high stability. It is believed that this study would provide an effective approach to preparing a photocatalyst and broaden the potential application of cellulose nanofibrils in photocatalysis.

Sunflower Leaf Structure Affects Chlorophyll a Fluorescence Induction Kinetics In Vivo.

Chlorophyll a fluorescence induction kinetics (CFI) is an important tool that reflects the photosynthetic function of leaves, but it remains unclear whether it is affected by leaf structure. Therefore, in this study, the leaf structure and CFI curves of sunflower and sorghum seedlings were analyzed. Results revealed that there was a significant difference between the structures of palisade and spongy tissues in sunflower leaves. Their CFI curves, measured on both the adaxial and abaxial sides, also differed significantly. However, the differences in the leaf structures and CFI curves between both sides of sorghum leaves were not significant. Further analysis revealed that the differences in the CFI curves between the adaxial and abaxial sides of sunflower leaves almost disappeared due to reduced incident light scattering and refraction in the leaf tissues; more importantly, changes in the CFI curves of the abaxial side were greater than the adaxial side. Compared to leaves grown under full sunlight, weak light led to decreased differences in the CFI curves between the adaxial and abaxial sides of sunflower leaves; of these, changes in the CFI curves and palisade tissue structure on the adaxial side were more obvious than on the abaxial side. Therefore, it appears that large differences in sunflower leaf structures may affect the shape of CFI curves. These findings lay a foundation for enhancing our understanding of CFI from a new perspective.

A Changing Light Environment Induces Significant Lateral CO2 Diffusion within Maize Leaves.

A leaf structure with high porosity is beneficial for lateral CO2 diffusion inside the leaves. However, the leaf structure of maize is compact, and it has long been considered that lateral CO2 diffusion is restricted. Moreover, lateral CO2 diffusion is closely related to CO2 pressure differences (ΔCO2). Therefore, we speculated that enlarging the ΔCO2 between the adjacent regions inside maize leaves may result in lateral diffusion when the diffusion resistance is kept constant. Thus, the leaf structure and gas exchange of maize (C4), cotton (C3), and other species were explored. The results showed that maize and sorghum leaves had a lower mesophyll porosity than cotton and cucumber leaves. Similar to cotton, the local photosynthetic induction resulted in an increase in the ΔCO2 between the local illuminated and the adjacent unilluminated regions, which significantly reduced the respiration rate of the adjacent unilluminated region. Further analysis showed that when the adjacent region in the maize leaves was maintained under a steady high light, the photosynthesis induction in the local regions not only gradually reduced the ΔCO2 between them but also progressively increased the steady photosynthetic rate in the adjacent region. Under field conditions, the ΔCO2, respiration, and photosynthetic rate of the adjacent region were also markedly changed by fluctuating light in local regions in the maize leaves. Consequently, we proposed that enlarging the ΔCO2 between the adjacent regions inside the maize leaves results in the lateral CO2 diffusion and supports photosynthesis in adjacent regions to a certain extent under fluctuating light.

Integrated metabolome and transcriptome analysis of the anthocyanin biosynthetic pathway in relation to color mutation in miniature roses.

BACKGROUND: Roses are famous ornamental plants worldwide. Floral coloration is one of the most prominent traits in roses and is mainly regulated through the anthocyanin biosynthetic pathway. In this study, we investigated the key genes and metabolites of the anthocyanin biosynthetic pathway involved in color mutation in miniature roses. A comparative metabolome and transcriptome analysis was carried out on the Neptune King rose and its color mutant, Queen rose, at the blooming stage. Neptune King rose has light pink colored petals while Queen rose has deep pink colored petals. RESULT: A total of 190 flavonoid-related metabolites and 38,551 unique genes were identified. The contents of 45 flavonoid-related metabolites, and the expression of 15 genes participating in the flavonoid pathway, varied significantly between the two cultivars. Seven anthocyanins (cyanidin 3-O-glucosyl-malonylglucoside, cyanidin O-syringic acid, cyanidin 3-O-rutinoside, cyanidin 3-O-galactoside, cyanidin 3-O-glucoside, peonidin 3-O-glucoside chloride, and pelargonidin 3-O-glucoside) were found to be the major metabolites, with higher abundance in the Queen rose. Thirteen anthocyanin biosynthetic related genes showed an upregulation trend in the mutant flower, which may favor the higher levels of anthocyanins in the mutant. Besides, eight TRANSPARENT TESTA 12 genes were found upregulated in Queen rose, probably contributing to a high vacuolar sequestration of anthocyanins. Thirty transcription factors, including two MYB and one bHLH, were differentially expressed between the two cultivars. CONCLUSIONS: This study provides important insights into major genes and metabolites of the anthocyanin biosynthetic pathway modulating flower coloration in miniature rose. The results will be conducive for manipulating the anthocyanin pathways in order to engineer novel miniature rose cultivars with specific colors.

Photosynthetic acclimation during low-light-induced leaf senescence in post-anthesis maize plants.

Low light conditions not only induce leaf senescence, but also photosynthetic acclimation. This study aimed to determine whether plants exhibit photosynthetic acclimation during low-light-induced leaf senescence. The influences of shading on leaf senescence and photosynthetic acclimation were explored in post-anthesis maize plants. The results showed that whole shading (WS) of maize plants accelerated leaf senescence, whereas partial shading (PS) slowed leaf senescence. WS led to larger decreases in the photosynthetic rate (Pn) and stomatal conductance (Gs) compared to those of the PS treatment. Interestingly, chlorophyll a fluorescence (ChlF) demonstrated that the absorption flux (ABS/CSo) and trapped energy flux (TRo/CSo) per cross section in leaves remained relatively stable under WS, whereas significant decreases in the active PSII reaction centers (RC/CSo) resulted in considerable increases in absorption (ABS/RC) and trapped energy flux (TRo/RC) per reaction center. ABS/CSo, TRo/CSo, ABS/RC, and TRo/RC increased markedly under PS, whereas there were slight decreases in RC/CSo and electron transport activity. These results suggest that the PS treatment resulted in obvious improvements in the absorption and capture of light energy in shaded leaves. Further analysis demonstrated that both the WS and PS treatments resulted in a greater decrease in the activity of Rubisco compared to that of phosphoenolpyruvate carboxylase (PEPC). Moreover, PEPC activity in PS was maintained at a high level. Consequently, the current study proposed that the improvement of the absorption and capture of light energy and the maintenance of PEPC activity of mesophyll cells were due to photosynthetic acclimation of low-light-induced leaf senescence in maize plants. In addition, the rate of senescence of vascular bundle cells in maize leaves exceeded that of mesophyll cells under low light, showing obvious tissue specificity.

Do rapid photosynthetic responses protect maize leaves against photoinhibition under fluctuating light?

Plants in their natural environment are often exposed to fluctuating light because of self-shading and cloud movements. As changing frequency is a key characteristic of fluctuating light, we speculated that rapid light fluctuation may induce rapid photosynthetic responses, which may protect leaves against photoinhibition. To test this hypothesis, maize seedlings were grown under fluctuating light with various frequencies (1, 10, and 100 cycles of fluctuations/10 h), and changes in growth, chlorophyll content, gas exchange, chlorophyll a fluorescence, and P700 were analyzed carefully. Our data show that though the growth and light-saturated photosynthetic rate were depressed by rapidly fluctuating light, photosynthesis induction was clearly speeded up. Furthermore, more rapid fluctuation of light strikingly reduced the chlorophyll content, while thermal dissipation was triggered and enhanced. The chlorophyll a fluorescence induction kinetics and P700 absorption results showed that the activities of both photosystem II and photosystem I decreased as the frequency of the fluctuating light increased. In all treatments, the light intensities of the fluctuating light were kept constant. Therefore, rapid light fluctuation frequency itself induced the acceleration of photosynthetic induction and the enhancement of photoprotection in maize seedlings, which play important roles in protecting photosynthetic apparatus against fluctuating high light to a certain extent.

Local weak light induces the improvement of photosynthesis in adjacent illuminated leaves in maize seedlings.

To copy with highly heterogeneous light environment, plants can regulate photosynthesis locally and systemically, thus, maximizing the photosynthesis of individual plants. Therefore, we speculated that local weak light may induce the improvement of photosynthesis in adjacent illuminated leaves in plants. In order to test this hypothesis, maize seedlings were partially shaded, and gas exchange, chlorophyll a fluorescence and biochemical analysis were carefully assessed. It was shown that local shading exacerbated the declines in the photosynthetic rates, chlorophyll contents, electron transport and carbon assimilation-related enzyme activities in shaded leaves as plants growth progressed. While, the decreases of these parameters in adjacent illuminated leaves of shaded plants were considerably alleviated compared to the corresponding leaves of control plants. Obviously, the photosynthesis in adjacent illuminated leaves in shaded plants was improved by local shading, and the improvement in adjacent lower leaves was larger than that in adjacent upper ones. As growth progressed, local shading induced higher abscisic acid contents in shaded leaves, but it alleviated the increase in the abscisic acid contents in adjacent leaves in shaded plants. Moreover, the difference in sugar content between shaded leaves and adjacent illuminated ones was gradually increased. Consequently, local weak light suppressed the photosynthesis in shaded leaves, while it markedly improved the photosynthesis of adjacent illuminated ones. Sugar gradient between shaded leaves and adjacent illuminated ones might play a key role in photosynthetic regulation of adjacent illuminated leaves.

Individual or combined transcatheter arterial chemoembolization and radiofrequency ablation for hepatocellular carcinoma: a time-to-event meta-analysis.

BACKGROUND: There is still some debate as to whether transcatheter arterial chemoembolization (TACE) plus radiofrequency ablation (RFA) is better than TACE or RFA alone. This meta-analysis aimed to compare the efficacy and safety of TACE plus RFA for hepatocellular carcinoma (HCC) with RFA or TACE alone. METHODS: We searched PubMed, MEDLINE, Embase, Cochrane Library, and CNKI (China National Knowledge Infrastructure) for all relevant randomized controlled trials and retrospective studies reporting overall survival (OS), recurrence-free survival (RFS), and complications of TACE plus RFA for HCC, compared with RFA or TACE alone. RESULTS: Twenty-one studies involving 3413 patients were included. TACE combined with RFA was associated with better OS (hazard ratio [HR]=0.62, 95% confidence intervals [CI] = 0.55-0.71, P < 0.001) and RFS (HR = 0.52, 95% CI = 0.39-0.69, P < 0.001) than TACE alone; compared with RFA alone, TACE plus RFA resulted in longer OS (HR = 0.63, 95% CI = 0.53-0.75, P < 0.001) and RFS (HR = 0.60, 95% CI = 0.51-0.71, P < 0.001). Subgroup analyses by tumor size also showed that combined treatment resulted in better OS and RFS compared with RFA alone in patients with HCC larger than 3 cm. Combined treatment resulted in similar rate of major complications compared with TACE or RFA alone (OR = 1.78, 95% CI = 0.99-3.20, P = 0.05; OR = 1.00, 95% CI = 0.42-2.38, P = 1.00, respectively). CONCLUSIONS: TACE combined with RFA was more effective for HCC than TACE alone. For patients with a tumor larger than 3 cm, the combined treatment also achieved a better effect than RFA alone.

Whole-transcriptome sequencing identifies a distinct subtype of acute lymphoblastic leukemia with predominant genomic abnormalities of EP300 and CREBBP.

Chromosomal translocations are a genomic hallmark of many hematologic malignancies. Often as initiating events, these structural abnormalities result in fusion proteins involving transcription factors important for hematopoietic differentiation and/or signaling molecules regulating cell proliferation and cell cycle. In contrast, epigenetic regulator genes are more frequently targeted by somatic sequence mutations, possibly as secondary events to further potentiate leukemogenesis. Through comprehensive whole-transcriptome sequencing of 231 children with acute lymphoblastic leukemia (ALL), we identified 58 putative functional and predominant fusion genes in 54.1% of patients (n = 125), 31 of which have not been reported previously. In particular, we described a distinct ALL subtype with a characteristic gene expression signature predominantly driven by chromosomal rearrangements of the ZNF384 gene with histone acetyltransferases EP300 and CREBBP ZNF384-rearranged ALL showed significant up-regulation of CLCF1 and BTLA expression, and ZNF384 fusion proteins consistently showed higher activity to promote transcription of these target genes relative to wild-type ZNF384 in vitro. Ectopic expression of EP300-ZNF384 and CREBBP-ZNF384 fusion altered differentiation of mouse hematopoietic stem and progenitor cells and also potentiated oncogenic transformation in vitro. EP300- and CREBBP-ZNF384 fusions resulted in loss of histone lysine acetyltransferase activity in a dominant-negative fashion, with concomitant global reduction of histone acetylation and increased sensitivity of leukemia cells to histone deacetylase inhibitors. In conclusion, our results indicate that gene fusion is a common class of genomic abnormalities in childhood ALL and that recurrent translocations involving EP300 and CREBBP may cause epigenetic deregulation with potential for therapeutic targeting.

The trimeric Hef-associated nuclease HAN is a 3'→5' exonuclease and is probably involved in DNA repair.

Nucleases play important roles in nucleic acid metabolism. Some archaea encode a conserved protein known as Hef-associated nuclease (HAN). In addition to its C-terminal DHH nuclease domain, HAN also has three N-terminal domains, including a DnaJ-Zinc-finger, ribosomal protein S1-like, and oligonucleotide/oligosaccharide-binding fold. To further understand HAN's function, we biochemically characterized the enzymatic properties of HAN from Pyrococcus furiosus (PfuHAN), solved the crystal structure of its DHH nuclease domain, and examined its role in DNA repair. Our results show that PfuHAN is a Mn2+-dependent 3'-exonuclease specific to ssDNA and ssRNA with no activity on blunt and 3'-recessive double-stranded DNA. Domain truncation confirmed that the intrinsic nuclease activity is dependent on the C-terminal DHH nuclease domain. The crystal structure of the DHH nuclease domain adopts a trimeric topology, with each subunit adopting a classical DHH phosphoesterase fold. Yeast two hybrid assay confirmed that the DHH domain interacts with the IDR peptide of Hef nuclease. Knockout of the han gene or its C-terminal DHH nuclease domain in Haloferax volcanii resulted in increased sensitivity to the DNA damage reagent MMS. Our results imply that HAN nuclease might be involved in repairing stalled replication forks in archaea.

DNA G-Quadruplexes as a Template To Direct Cyanine Dyes To Form H-Aggregates and Application of the Self-Assembly Entity as a New G-Quadruplexes Ligands Screening Platform.

The organization of organic chromophores to form H-/J-aggregates can result in new biomaterials with unique properties and applications. DNA-template self-assembly is one of the most attractive strategies to guide the formation of chromophore aggregates. However, the DNA templates are mainly limited to canonical nucleic acids structures [single (ss)- and double (ds)-stranded DNA]. DNA G-quadruplexes (GQs), with distinct and various structural features, were rarely exploited to guide the formation of dye aggregates. In this study, we present the spontaneous assembly of cyanine dye IR786 to form H-aggregates on DNA GQs exclusively, but no IR786 aggregates formed by adjusting the experimental parameters or on ss-/ds-DNA. Furthermore, on the basis of the assembly entity (GQs-IR786), an adaptive GQs-FID (fluorescence intercalator displacement) assay for screening of GQs ligands was developed. In contrast with the existing GQs-FID screening schemes, this assay displayed attractive performance in many aspects (such as turn-on signal output, broad screening range, and time saving). All these results have undoubtedly demonstrated the great values of DNA GQs as a template to guide the formation of dye aggregates. We hope that more GQs structures would be exploited as templates to expand the variety of functional materials in the future. Moreover, the specifically formed H-aggregates of IR786 on GQs are significant for GQs' detection, and we also expect that this GQs-FID assay would be further studied and finally applied to screen GQs ligands in a high-throughput manner in the future.

Molecular engineering of a dual emission near-infrared ratiometric fluorophore for the detection of pH at the organism level.

A near-infrared ratiometric fluorophore (NIR-HBT) was rationally designed and constructed by expanding both the excitation and emission wavelength of the classical ratiometric fluorophore 2-(benzothiazol-2-yl)phenol (HBT) into the near-infrared region. The NIR-HBT was easily synthesized by incorporating the HBT module into the hemicyanine skeleton and showed evident NIR ratiometric fluorophore characteristics. Further application of the new fluorophore for pH detection demonstrated that NIR-HBT possesses superior overall analytical performance and NIR-HBT was successfully applied for detection of acidosis caused by inflammation in living animal tissue, which indicated the potential application value of NIR-HBT in biological imaging and sensing.

[An efficient genetic knockout system based on linear DNA fragment homologous recombination for halophilic archaea].

With the development of functional genomics, gene-knockout is becoming an important tool to elucidate gene functions in vivo. As a good model strain for archaeal genetics, Haloferax volcanii has received more attention. Although several genetic manipulation systems have been developed for some halophilic archaea, it is time-consuming because of the low percentage of positive clones during the second-recombination selection. These classical gene knockout methods are based on DNA recombination between the genomic homologous sequence and the circular suicide plasmid, which carries a pyrE selection marker and two DNA fragments homologous to the upstream and downstream fragments of the target gene. Many wild-type clones are obtained through a reverse recombination between the plasmid and genome in the classic gene knockout method. Therefore, it is necessary to develop an efficient gene knockout system to increase the positive clone percentage. Here we report an improved gene knockout method using a linear DNA cassette consisting of upstream and downstream homologous fragments, and the pyrE marker. Gene deletions were subsequently detected by colony PCR analysis. We determined the efficiency of our knockout method by deleting the xpb2 gene from the H. volcanii genome, with the percentage of positive clones higher than 50%. Our method provides an efficient gene knockout strategy for halophilic archaea.

Enhancing photocatalytic destruction of lignin via cellulose derived carbon quantum dots/g-C3N4 heterojunctions.

Lignocellulosic biomass exhibits a promising potential for production of carbon materials. Nitrogen and phosphorus co-doped carbon quantum dots (N,P-CQDs) were fabricated via (NH4)2HPO4 assisted hydrothermal treatment of cellulose pulp fibers. The as-prepared N,P-CQDs were characterized by HRTEM, FTIR, fluorescence and UV-vis, and then incorporated into g-C3N4 (CN) through sonication and liquid deposition, forming N,P-CQDs/sonication treated g-C3N4 (C-SCN) composites, which were then explored as photocatalysts. The photocatalytic ability of C-SCN towards model lignin was further analyzed. The results showed that, the fluorescence intensity and photoluminescence performance of N,P-CQDs were much higher than that of CQDs; the heterojunction was successfully constructed between the composites of N,P-CQDs and SCN; the incorporation of N,P-CQDs enhanced the visible light absorption, but reduced the band gap of the composite heterojunction; the resultant photocatalysts exhibited a good photocatalytic ability of model lignin via catalyze the fracture of ß-O-4' ether bond and CC bond, i.e., the photocatalytic degradation ratio reached up to 95.5 %; and the photocatalytic reaction generated some valuable organics such as phenyl formate, benzaldehyde, and benzoic acid. This study would promote the high value-added utilization of lignocellulosic resources especially in the transformation of lignin, conforming the concept of sustainable development.

Upgrading lignin macromolecular by green and recyclable ternary deep eutectic solvents.

Lignin is the most abundant natural aromatic macromolecule in the nature, but its high value-added utilization has been seriously hindered by the highly random and branched structures and the high difficulty in separation and purification. A microwave-assisted ternary deep eutectic solvent (DES) composed by formic acid, lactic acid and choline chloride was developed for lignin pretreatment. The effects of three types of DES on main characteristics of lignin were investigated, and the corresponding dissolution mechanism was proposed. The results showed that, the microwave-assisted ternary DES pretreatment showed an obvious improvement on main characteristics of regenerated lignin, e.g., a higher purity, lower molecular weight with reduced dispersity, improved thermal stability, higher phenolic hydroxyl content, and increased antioxidative activity in comparison with control. It is expected that the lignin macromolecular can be facile regulated and upgraded by the proposed ternary DES.