Dehydroabietylamine exerts antitumor effects by affecting nucleotide metabolism in gastric cancer.

Nucleotide metabolism is the ultimate and most critical link in the self-replication process of tumors, including gastric cancer (GC). However, in clinical treatment, classic anti-tumor drugs such as 5-fluorouracil (5-FU) are mostly metabolic analogues of purines or pyrimidines, which lack specificity for tumor cells and therefore have significant side effects. It is unclear whether there are other drugs that can target nucleotide metabolism, except for nucleic acid analogues. Here, we found that a natural compound, dehydroabietylamine (DHAA), significantly reduced the viability and proliferation of GC cells and organoids. DHAA disrupts purine and pyrimidine metabolism of GC cells, causing DNA damage and further inducing apoptosis. DHAA treatment decreased transcription and protein levels of key enzymes involved in nucleotide metabolism pathway, with significant reductions in the expression of pyrimidine metabolism key enzymes CAD, DHODH, and purine metabolism key enzymes PAICS. We also found that DHAA directly binds to and reduces the expression of Forkhead box K2 (FOXK2), a common transcription factor for these metabolic enzymes. Ultimately, DHAA was shown to delay tumorigenesis in K19-Wnt1/C2mE transgenic mice model and reduce levels of CAD, DHODH, and PAICS in vivo. We demonstrate that DHAA exerts an anticancer effect on GC by targeting transcription factor FOXK2, reducing transcription of key genes for nucleotide metabolism and impairing nucleotide biosynthesis, thus DHAA is a promising candidate for GC therapy.

Short-term high-temperature pretreated compost increases its application value by altering key bacteria phenotypes.

Short-term high-temperature pretreatment can effectively shorten the maturity period of organic waste composting and improve the fertilizer efficiency and humification degree of products. To investigate the effect and mechanism of the end products on the saline-alkali soil improvement and plant growth, the short-term high-temperature pretreatment composting (SHC) and traditional composting (STC) were separately blended with saline-alkali soil in a ratio of 0-40 % to establish a soil-fertilizer blended matrix for cultivating Lolium perenne L. The pot experiments combined with principal component analysis showed Lolium perenne L. planted in 20 % SHC-blended saline-alkali soil had the best growth effect, and its biomass, chlorophyll content, and plant height were 109-113 % higher than STC. The soil physicochemical property analysis showed that SHC and STC increased the soil nutrient content, humification degree, and enzyme activity at any blending ratio. The microbial analysis showed that 20 % SHC in the saline-alkali soil stimulated the growth of functional microorganisms and the addition of SHC promoted the sulfur cycle, nitrogen fixation, and carbon metabolism in the soil-plant system. The correlation analysis showed that pH; nutrient contents; and urease, catalase, sucrase, and phosphatase activities in the saline-alkali soil were significantly correlated with plant growth indexes (p < 0.05). Georgenia and norank_f__Fodinicurvataceae had a stronger correlation with four types of enzyme activities (p < 0.01). SHC improved the saline-alkali soil and promoted plant growth by adjusting soil pH, increasing soil nutrients, and influencing soil enzyme activity and dominant flora. This study provides a theoretical basis for applying SHC products in soil improvement.

Discovery of digallic acid as XOD/URAT1 dual target inhibitor for the treatment of hyperuricemia.

The development of XOD/URAT1 dual target inhibitors has emerged as a promising therapeutic strategy for the management of hyperuricemia. Here, through virtual screening, we have identified digallic acid as a novel dual target inhibitor of XOD/URAT1 and subsequently evaluated its pharmacological properties, pharmacokinetics, and toxicities. Digallic acid inhibited URAT1 with an IC50 of 5.34 ± 0.65 µM, which is less potent than benzbromarone (2.01 ± 0.36 µM) but more potent than lesinurad (10.36 ± 1.23 µM). Docking and mutation analysis indicated that residues S35, F241 and R477 of URAT1 confer a high affinity for digallic acid. Digallic acid inhibited XOD with an IC50 of 1.04 ± 0.23 µM. Its metabolic product, gallic acid, inhibited XOD with an IC50 of 0.91 ± 0.14 µM. Enzyme kinetic studies indicated that both digallic acid and gallic acid act as mixed-type XOD inhibitors. It shares the same binding mode as digallic acid, and residues E802, R880, F914, T1010, N768 and F1009 contribute to their high affinity. The anion group (carboxyl) of digallic acid contribute significantly to its inhibition activity on both XOD and URAT1 as indicated by docking analysis. Remarkably, at a dosage of 10 mg/kg in vivo, digallic acid exhibited a stronger urate-lowering and uricosuric effect compared to the positive drug benzbromarone and lesinurad. Pharmacokinetic study indicated that digallic acid can be hydrolyzed into gallic acid in vivo and has a t1/2 of 0.77 ± 0.10 h. Further toxicity evaluation indicated that digallic acid exhibited no obvious renal toxicity, as reflected by CCK-8, biochemical analysis (CR and BUN) and HE examination. The findings of our study can provide valuable insights for the development of XOD/URAT1 dual target inhibitors, and digallic acid deserves further investigation as a potential anti-hyperuricemic drug.

Superelastic carbon aerogels with anisotropic and hierarchically-enhanced cellular structure for wearable piezoresistive sensors.

Elastic carbon aerogels have promising applications in the field of wearable sensors. Herein, a new strategy for preparing carbon aerogels with excellent compressive strength and strain, shape recovery, and fatigue resistance was proposed based on the structure design and carbonization optimization of nanocellulose-based precursor aerogels. By the combination of directional freezing and zinc ion cross-linking, bacterial cellulose (BC)/alginate (SA) composite aerogels with high elasticity and compressive strength were first achieved. The existance of zinc ions also significantly improved the carbon retention rate and inhibited structural shrinkage, thus making the carbon aerogels retain ultra-high elasticity and fatigue resistance after compression. Moreover, the carbon aerogel possessed excellent piezoresistive pressure sensing performance with a wide detection range of 0-7.8 kPa, high sensitivity of 11.04 kpa-1, low detection limit (2 % strain), fast response (112 ms), and good durability (over 1,000 cycles). Based on these excellent properties, the carbon aerogel pressure sensors were further successfully used for human motion monitoring, from joint motion to and speech recognition.

Frost-resistant nanocellulose-based organohydrogel with high mechanical strength and transparency.

Improving mechanical strength and frost-resistance is an important research direction in the field of hydrogel materials. Herein, using bacterial nanocellulose (BC) as a reinforcing agent and polyvinyl alcohol (PVA) as a polymer matrix, a frost-resistant organohydrogel was constructed via the freezing-thawing method in a new binary solvent system of N, N-dimethylformamide and water (DMF-H2O), which was designed according to the Hansen Solubility Parameter. Owing to the solvent-induced crystallization effect that led to the enhanced 3D hydrogen bonding network during the freezing-thawing process, the optimal organohydrogel achieved excellent mechanical properties with the tensile strength of 2,974 kPa and the stretchability of 277 % at room temperature, respectively. In the visiblelight range, the organohydrogel demonstrated high transmittance. Moreover, the presence of a DMF-H2O binary solvent endows it with frost-resistance, retaining the tensile strength of 508 kPa and a stretchability of 190 % even at -70 °C, respectively. This kind of transparent, frost-resistant organohydrogel has potential uses in harsh settings due to its great mechanical strength.

Effect of Mowing on Wheat Growth at Seeding Stage.

Winter wheat is used as forage at the tillering stage in many countries; however, the regrowth pattern of wheat after mowing remains unclear. In this study, the growth patterns of wheat were revealed through cytological and physiological assessments as well as transcriptome sequencing. The results of agronomic traits and paraffin sections showed that the shoot growth rate increased, but root growth was inhibited after mowing. The submicroscopic structure revealed a decrease in heterochromatin in the tillering node cell and a change in mitochondrial shape in the tillering node and secondary root. Analysis of the transcriptome showed the number of differentially expressed genes (DEGs) involved in biological processes, cellular components, and molecular functions; 2492 upregulated DEGs and 1534 downregulated DEGs were identified. The results of the experimental study showed that mowing induced expression of DEGs in the phenylpropanoid biosynthesis pathway and increased the activity of PAL and 4CL. The upregulated DEGs in the starch and sucrose metabolism pathways and related enzyme activity alterations indicated that the sugar degradation rate increased. The DEGs in the nitrogen metabolism pathway biosynthesis of the amino acids, phenylpropanoid biosynthesis metabolism, and in the TCA pathway also changed after mowing. Hormone content and related gene expression was also altered in the tillering and secondary roots after mowing. When jasmonic acid and ethylene were used to treat the wheat after mowing, the regeneration rate increased, whereas abscisic acid inhibited regrowth. This study revealed the wheat growth patterns after mowing, which could lead to a better understanding of the development of dual-purpose wheat.

Superelastic chitin nanofibril/chitosan aerogel for effective circulating and continuous oil-water separation.

Elastic and hydrophobic aerogels have received a lot of attention in dealing with the increasing oil pollution due to their recyclable properties. Herein, we present an ultralight and superelastic aerogel with highly oriented polygon structure based on chitin nanofibril (ChNF) and chitosan (CS) by directional freezing. The chemical cross-linking enables good mechanical strength at low aerogel density. After 500 compression-release cycles, the aerogel can retain the deformation recovery rate of 88 % in air, demonstrating the excellent resilience. The bio-based aerogel has high absorption capacity (52-114 g/g) for various oils and organic solvents, and it is able to achieve the absorption retention of 90 % even after 20 absorption-extrusion cycles. Moreover, owing to the good elasticity, the pore size of the aerogel can be adjusted by compression to selectively separate water-in-oil emulsions of different particle sizes with separation efficiencies higher than 99.5 %. The bio-based aerogel with good cycle performance has broad application prospects in the field of oil-water separation.

Genome-wide identification, classification, and expression analysis of heat shock transcription factor family in switchgrass (Panicum virgatum L.).

Switchgrass is one of the most promising bioenergy crops and is generally cultivated in arid climates and poor soils. Heat shock transcription factors (Hsfs) are key regulators of plant responses to abiotic and biotic stressors. However, their role and mechanism of action in switchgrass have not been elucidated. Hence, this study aimed to identify the Hsf family in switchgrass and understand its functional role in heat stress signal transduction and heat tolerance by using bioinformatics and RT-PCR analysis. Forty-eight PvHsfs were identified and divided into three main classes based on their gene structure and phylogenetic relationships: HsfA, HsfB, and HsfC. The results of the bioinformatics analysis showed a DNA-binding domain (DBD) at the N-terminal in PvHsfs, and they were not evenly distributed on all chromosomes except for chromosomes 8 N and 8 K. Many cis-elements related to plant development, stress responses, and plant hormones were identified in the promoter sequence of each PvHsf. Segmental duplication is the primary force underlying Hsf family expansion in switchgrass. The results of the expression pattern of PvHsfs in response to heat stress showed that PvHsf03 and PvHsf25 might play critical roles in the early and late stages of switchgrass response to heat stress, respectively, and HsfB mainly showed a negative response to heat stress. Ectopic expression of PvHsf03 in Arabidopsis significantly increased the heat resistance of seedlings. Overall, our research lays a notable foundation for studying the regulatory network in response to deleterious environments and for further excavating tolerance genes in switchgrass.

Efficient and Controllable Synthesis of 1-Aminoanthraquinone via High-Temperature Ammonolysis Using Continuous-Flow Method.

Anthraquinone dyes are the second most important type of dyes after azo dyes. In particular, 1-aminoanthraquinone has been extensively utilized in the preparation of diverse anthraquinone dyes. This study employed a continuous-flow method to synthesize 1-aminoanthraquinone safely and efficiently through the ammonolysis of 1-nitroanthraquinone at high temperatures. Various conditions (reaction temperature, residence time, molar ratio of ammonia to 1-nitroanthraquinone (M-ratio), and water content) were investigated to explore the details of the ammonolysis reaction behavior. Operation conditions for the continuous-flow ammonolysis were optimized using Box-Behnken design in the response surface methodology, and ~88% yield of 1-aminoanthraquinone could be achieved with an M-ratio of 4.5 at 213 °C and 4.3 min. The developed process's reliability was evaluated by performing a 4 h process stability test. The kinetic behavior for the preparation of 1-aminoanthraquinone was investigated under continuous-flow mode to guide the reactor design and to gain a deeper understanding of the ammonolysis process.

Integrated genome-centric metagenomic and metaproteomic analyses unravel the responses of the microbial community to ammonia stress.

Ammonia is a major inhibitor in anaerobic digestion of nitrogen-rich organic wastes. In this study, integrated genome-centric metagenomic and metaproteomic analyses were used to identify the key microorganisms and metabolic links causing instability by characterizing the process performance, microbial community, and metabolic responses of key microorganisms during endogenous ammonia accumulation. The identification of 89 metagenome-assembled genomes and analysis of their abundance profile in different operational phases permitted the identification of key taxa (Firmicutes and Proteobacteria) causing poor performance. Metabolic reconstruction indicated that the key taxa had the genetic potential to participate in the metabolism of C2C5 volatile fatty acids (VFAs). Further investigation suggested that during Phase I, the total ammonia nitrogen (TAN) level was maintained below 2000 mg N/L, and the reactor showed a high methane yield (478.30 ± 33.35 mL/g VS) and low VFAs concentration. When the TAN accumulated to > 2000 mg N/L, acid accumulation, mainly of acetate, began to occur, and the methane yield gradually decreased to 330.44 mL/g VS (Phase II). During this phase, the VFA degradation functions of the community were mainly mediated by Firmicutes. Approximately 61.54% of significant differentially expressed proteins (DEPs) related to acetate metabolism in Firmicutes were down-regulated, which led to an increase in acetate concentration to 4897.91 ± 1558.96 mg/L. However, the reactor performance showed spontaneous recovery without any interference (Phase III), during which Firmicutes gradually adapted to the high ammonia conditions. Approximately 75% of the significant DEPs related to acetate metabolism of Proteobacteria were also up-regulated in Phase III compared with Phase II; thus, VFA-related metabolic functions of the community were enhanced, which resulted in a decrease in the total VFA concentration to 195.39 mg/L. When the TAN increased above 4000 mg N/L, the system gradually showed acid accumulation dominated by propionate, accompanied by a second decrease in methane yield (Phase IV). During this phase, the number of up-regulated and down-regulated proteins related to acetate metabolism of Firmicutes and butyrate/valerate metabolism of Proteobacteria was comparable with that of Phase III, indicating that the metabolic functions related to acetate, butyrate, and valerate of the microbial community were not significantly affected. However, for propionate metabolism, the expression activity of fumarate hydratase from Firmicutes and Proteobacteria was severely inhibited by ammonia, as shown by down-regulation ratios of 63.64% and 85.71%, respectively. No protein with the same function that was not inhibited by ammonia could be detected, and the fumarate degradation function of the microbial community was severely damaged, leading to blocked propionate metabolism and irreversible deterioration of reactor performance. This study has provided a new perspective on the microecological mechanisms of ammonia inhibition.

Analysis of morphological traits and regulatory mechanism of a semi-dwarf, albino, and blue grain wheat line.

The plant height and leaf color are important traits in crops since they contribute to the production of grains and biomass. Progress has been made in mapping the genes that regulate plant height and leaf color in wheat (Triticum aestivum L.) and other crops. Wheat line DW-B (dwarfing, white leaves, and blue grains) with semi-dwarfing and albinism at the tillering stage and re-greening at the jointing stage was created using Lango and Indian Blue Grain. Transcriptomic analyses of the three wheat lines at the early jointing stages indicated that the genes of gibberellin (GA) signaling pathway and chlorophyll (Chl) biosynthesis were expressed differently in DW-B and its parents. Furthermore, the response to GA and Chl contents differed between DW-B and its parents. The dwarfing and albinism in DW-B were owing to defects in the GA signaling pathway and abnormal chloroplast development. This study can improve understanding of the regulation of plant height and leaf color. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01379-z.

Convergent Biocatalytic Mediated Synthesis of siRNA.

New technologies are required to combat the challenges faced with manufacturing commercial quantities of oligonucleotide drug substances which are required for treating large patient populations. Herein we report a convergent biocatalytic synthesis strategy for an Alnylam model siRNA. The siRNA chemical structure includes several of the unnatural modifications and conjugations typical of siRNA drug substances. Using Almac's 3-2-3-2 hybrid RNA ligase enzyme strategy that sequentially ligates short oligonucleotide fragments (blockmers), the target siRNA was produced to high purity at 1 mM concentration. Additional strategies were investigated including the use of polynucleotide kinase phosphorylation and the use of crude blockmer starting materials without chromatographic purification. These findings highlight a path toward a convergent synthesis of siRNAs for large-scale manufacture marrying both enzymatic liquid and classical solid-phase synthesis.

Enhancing the Activity of an Alcohol Dehydrogenase by Using "Aromatic Residue Scanning" at Potential Plasticity Sites.

An alcohol dehydrogenase LkADH was successfully engineered to exhibit improved activity and substrate tolerance for the production of (S)-2-chloro-1-(3,4-difluorophenyl)ethanol, an important precursor of ticagrelor. Five potential hotspots were identified for enzyme mutagenesis by using natural residue abundance as an indicator to evaluate their potential plasticity. A semi-rational strategy named "aromatic residue scanning" was applied to randomly mutate these five sites simultaneously by using tyrosine, tryptophan, and phenylalanine as "exploratory residues" to introduce steric hindrance or potential π-π interactions. The best variant Lk-S96Y/L199W identified with 17.2-fold improvement in catalytic efficiency could completely reduce up to 600 g/L (3.1 M) 2-chloro-1-(3,4-difluorophenyl)ethenone in 12 h with >99.5 % ee, giving the highest space-time yield ever reported. This study, therefore, offers a strategy for mutating alcohol dehydrogenase to reduce aromatic substrates and provides an efficient variant for the efficient synthesis of (S)-2-chloro-1-(3,4-difluorophenyl)ethanol.

Evaluation of digestate-derived biochar to alleviate ammonia inhibition during long-term anaerobic digestion of food waste.

The feasibility of using food waste anaerobic digestate-derived biochar (FWDB) to mitigate ammonia toxicity in an anaerobic digester was evaluated. The optimal conditions for preparing and adding the activated FWDB were explored using response surface experiments, and the long-term effects of adding activated FWDB on digester performance under optimum conditions were verified in semi-continuous experiments. The results showed that the optimal preparation and addition conditions for activated FWDB were pyrolysis temperature of 565 °C, particle size of 0-0.30 mm, and dosage of 15.52 g·L-1. During the long-term operation of the digesters, when the total ammonia nitrogen (TAN) concentration was higher than 2000 mg·L-1, the control and experimental digesters showed deteriorated reactor performance. Volatile fatty acids in the control digester accumulated to 20,306 mg·L-1 after the TAN concentration increased to 3391 mg·L-1, the methane yield decreased to 31 mL·g VS-1, and the digester experienced process failure. In contrast, the experimental digester with added activated FWDB only suffered a slight short-term accumulation of acetate and a slight decline in methane yield. This may be attributed to the adsorption of NH4+/NH3 by activated FWDB, which reduced the TAN concentration in the anaerobic digestion (AD) system and mitigated ammonia toxicity. Microbial analysis and metagenome predictions demonstrated that the community richness, diversity, and evenness, as well as the abundance of acetogens and related key genes (ACSM1, paaF, and acdA) were higher in the experimental digester than in the control digester. This study provides a closed-loop AD enhancement strategy by pyrolysis of digestate and in-situ supplementation into the digester.

Genome-Wide Identification of Wheat KNOX Gene Family and Functional Characterization of TaKNOX14-D in Plants.

The KNOX genes play important roles in maintaining SAM and regulating the development of plant leaves. However, the TaKNOX genes in wheat are still not well understood, especially their role in abiotic stress. In this study, a total of 36 KNOX genes were identified, and we demonstrated the function of the TaKNOX14-D gene under mechanical injury and cold stress. Thirty-six TaKNOX genes were divided into two groups, and thirty-four TaKNOX genes were predicted to be located in the nucleus by Cell-PLoc. These genes contained five tandem duplications. Fifteen collinear gene pairs were exhibited in wheat and rice, one collinear gene pair was exhibited in wheat and Arabidopsis. The phylogenetic tree and motif analysis suggested that the TaKNOX gene appeared before C3 and C4 diverged. Gene structure showed that the numbers of exons and introns in TaKNOX gene are different. Wheat TaKNOX genes showed different expression patterns during the wheat growth phase, with seven TaKNOX genes being highly expressed in the whole growth period. These seven genes were also highly expressed in most tissues, and also responded to most abiotic stress. Eleven TaKNOX genes were up-regulated in the tillering node during the leaf regeneration period after mechanical damage. When treating the wheat with different hormones, the expression patterns of TaKNOX were changed, and results showed that ABA promoted TaKNOX expression and seven TaKNOX genes were up-regulated under cytokinin and auxin treatment. Overexpression of the TaKNOX14-D gene in Arabidopsis could increase the leaf size, plant height and seed size. This gene overexpression in Arabidopsis also increased the compensatory growth capacity after mechanical damage. Overexpression lines also showed high resistance to cold stress. This study provides a better understanding of the TaKNOX genes.

Nitrogen removal from low COD/N interflow using a hybrid activated sludge membrane-aerated biofilm reactor (H-MABR).

A hybrid activated sludge membrane-aerated biofilm reactor based on a two-stage simultaneous nitrification-denitrification (SND) process was built, and its utility for treating interflow with low chemical oxygen demand (COD)/total nitrogen (TN) (COD/N) was explored. The operating performance, functional microbial communities, and functional genes for nitrogen metabolism were evaluated at low COD/N (4-1.3). The reactor could achieve stable operation at COD/N = 4-1.5, and the removal efficiency of COD, TN, and ammonia nitrogen was stable at 90.30 ± 2.36 %, 85.69 ± 2.22 %, and 89.52 ± 6.06 %, respectively. The SND rates were 70.89 % and 50.75 % when influent COD/N was 2.0 and 1.7, respectively, indicating that SND makes an important contribution to nitrogen removal under these two COD/N conditions. Microbial analysis revealed that the sampling sites with a high abundance of denitrification genes in the outer ring experienced aerobic conditions, inferring that aerobic denitrification also plays an important role in denitrification.

In-Situ Reaction Method to Synthetize Constant Solid-State Composites as Phase Change Materials for Thermal Energy Storage.

The encapsulation and heat conduction of molten salt are very important for its application in heat storage systems. The general practice is to solidify molten salt with ceramic substrate and enhance heat conduction with carbon materials, but the cycle stability is not ideal. For this reason, it is of practical significance to study heat storage materials with a carbon-free thermal conductive adsorption framework. In this paper, the in-situ reaction method was employed to synthetize the constant solid-state composites for high-temperature thermal energy storage. AlN is hydrolyzed and calcined to form h-Al2O3 with a mesoporous structure to prevent the leakage of molten eutectic salt at high temperature. Its excellent thermal conductivity simultaneously improves the thermal conductivity of the composites. It is found that 15CPCMs prepared with 15% water addition have the best thermal conductivity (4.928 W/m·K) and mechanical strength (30.2 MPa). The enthalpy and the thermal storage density of 15CPCMs are 201.4 J/g and 1113.6 J/g, respectively. Due to the excellent leak-proof ability and lack of carbon materials, the 15CPCMs can maintain almost no mass loss after 50 cycles. These results indicate that 15CPCMs have promising prospects in thermal storage applications.

3D printed PCL/ß-TCP cross-scale scaffold with high-precision fiber for providing cell growth and forming bones in the pores.

Scaffolds prepared by 3D printing are increasingly used in the field of bone tissue repair. However, on traditional 3D printed bone tissue engineering scaffolds, cells can only grow on the fiber surface and form bone. We designed a scaffold with a cross-scale structure of PCL/ß-TCP, which contains thick fibers with a diameter of 500 µm printed by FDM. And in the pores of the coarse fiber, the ultra-high precision fine fiber grid with a diameter of about 10 µm is filled by MEW mode. In cell experiments, cells can not only grow on the thick fiber surface of the cross-scale scaffold. At the same time, the mesh structure of fine fibers provides a bridge for cell growth, allowing cells to pass through the pores of thick fibers and grow in the pores and gradually cover the pores of the scaffold. In the osteoinduction experiment, ß-TCP in the PCL/ß-TCP composite provides Ca2+ and PO43- to the scaffold, which effectively promotes the osteogenic differentiation of cells on the scaffold. Compared with traditional scaffolds, the osteogenic performance of cross-scale scaffolds is greatly improved. Not only did bone form on the surface of the scaffold, but also obvious ALP expression and effective calcium precipitation appeared in the pores of the scaffold. This can effectively speed up the repair of bone defects. We believe that the 3D printed PCL/ß-TCP cross-scale scaffold with high-precision fibers has great application prospects in the field of bone tissue engineering.

3D printed high-resolution scaffold with hydrogel microfibers for providing excellent biocompatibility.

Melt electrowriting (MEW) can print high-resolution scaffolds with the ultrafine fibers from 800 nm to 20 µm. However, the cell seeding efficiency relatively low due to the large pore size of the MEW scaffold. Here, we reported a method to solve this dilemma by electrospinning a gelatin methacrylate (GelMA) hydrogel fibers membrane (HFM) on the MEW scaffold. This composite scaffold can own the controlled structures and porosity and excellent cell seeding performance. We systematically investigate the fabrication, morphology, and biocompatibility of composite scaffolds. The implanting of human umbilical vein endothelial cells(HUVES) showed excellent adhesion and biocompatibility on the composite scaffold. Moreover, the cells migrated gradually into the MEW scaffold along the GelMA HFM to form the cell sheet. We hold the opinion that the composite scaffolds have potential applications in the field of tissue engineering repair.

Investigation of hydrodynamics in high solid anaerobic digestion by particle image velocimetry and computational fluid dynamics: Role of mixing on flow field and dead zone reduction.

High solid anaerobic digestion (HSAD) was a potential organic waste treatment. Compared with low solid anaerobic digestion, it had the advantages of small footprint, less digestate, and low heating energy. However, HSAD's methane production is poor, mainly due to the complex hydrodynamics. In this study, computational fluid dynamics were utilized for HSAD's hydrodynamics investigation at 14.3% solid content and compared to the particle image velocimetry measurement. Then, effects of mixing on hydrodynamics were investigated. The results indicated that the diameter of impeller was critical for the radial mixing, and the distance between the impellers dictated the axial mixing. Besides, rotating speed affected flow velocities significantly, but displayed less effect on expanding the mixing range. Furthermore, HSAD's treating capacity could be increased at large extent by optimizing mixing. The visualization of the hydrodynamics in this study could potentially offer conceptual basis for HSAD's design in practical engineering.