Reversible Hydrogen Storage Media by g-CN Monolayer Decorated with NLi4: A First-Principles Study.

A two-dimensional graphene-like carbon nitride (g-CN) monolayer decorated with the superatomic cluster NLi4 was studied for reversible hydrogen storage by first-principles calculations. Molecular dynamics simulations show that the g-CN monolayer has good thermal stability at room temperature. The NLi4 is firmly anchored on the g-CN monolayer with a binding energy of -6.35 eV. Electronic charges are transferred from the Li atoms of NLi4 to the g-CN monolayer, mainly due to the hybridization of Li(2s), C(2p), and N(2p) orbitals. Consequently, a spatial local electrostatic field is formed around NLi4, leading to polarization of the adsorbed hydrogen molecules and further enhancing the electrostatic interactions between the Li atoms and hydrogen. Each NLi4 can adsorb nine hydrogen molecules with average adsorption energies between -0.152 eV/H2 and -0.237 eV/H2. This range is within the reversible hydrogen storage energy window. Moreover, the highest achieved gravimetric capacity is up to 9.2 wt%, which is superior to the 5.5 wt% target set by the U.S. Department of Energy. This study shows that g-CN monolayers decorated with NLi4 are a good candidate for reversible hydrogen storage.

Heat transport properties of novel carbon monolayer (net-Y): a comparative study with graphene.

With the rapid development of material preparation and quantum computation technologies, the discovery of superior electronic devices in the nanoscale has been widely facilitated. For materials for application in thermoelectric and thermal conductivity devices, their overall performance can be demonstrated by their inner heat transport efficiency. Thus, fundamental elucidation of the heat transport mechanism within low-dimensional materials with physical insight, is of great significance for novel electric device development. In addition, theoretical clarification can also help with the efficient control of the developed thermal devices, and furthermore, provide strategies to improve the efficiency of heat conversion. In this study, we focus on a novel carbon monolayer (net-Y) that is composed of sp2 hybridized C atoms, we systematically assess its practical applicability in electronic device design by conducting first-principles calculations. Furthermore, to obtain in-depth understanding of the factors that determine its heat transport efficiency, its mechanical and phonon spectrum related properties were also investigated. Through a comparative study with graphene, the heat transport mechanism of net-Y was successfully summarized; the methodology and theoretical findings presented in this study could provide an instructive reference for future experimental work.

Lower thermal conductivity of body centered cubic carbon (C14): a comparative study with diamond.

In recent years, the material preparation technology has ushered into a stage of rapid development, increasingly more carbon materials are found to display superior properties, making them suitable for designing nano-scale devices. Within the applications of electronic devices, a considerable amount of consumed energy has to be converted into heat; thus the efficiency of heat transport inside these devices can largely determine their overall performance. Decent elucidations of the heat transport mechanisms within low-dimensional materials will be helpful to achieve thermal management control of the related devices and furthermore, to improve their conversion efficiency. It is well understood that the heat transport within these kinds of materials is largely associated with their structural features. In this study, we focused on a novel material, body centered cubic carbon (C14), which is composed of sp3 hybridized carbon atoms. Such a novel material displays superior electronic properties; however, its thermal properties remain to be investigated. In order to systematically evaluate the practical applicability of this novel material, first-principles calculations were employed to systematically solve its structure; furthermore, its thermal conductivity, phonon dispersion spectrum, phonon properties, Grüneisen parameters, scattering phase space and mechanical properties were all described in detail. We found that C14 performs well in heat transport; and via systematical comparison with another allotrope, diamond, its transport mechanism was further summarized. We hope the physical insights provided by this study could serve as theoretical support for nano-scale device design.

Computational Evaluation of Al-Decorated g-CN Nanostructures as High-Performance Hydrogen-Storage Media.

Density functional theory (DFT) calculations were employed to solve the electronic structure of aluminum (Al)-doped g-CN and further to evaluate its performance in hydrogen storage. Within our configurations, each 2 × 2 supercell of this two-dimensional material can accommodate four Al atoms, and there exist chemical bonding and partial charge transfer between pyridinic nitrogen (N) and Al atoms. The doped Al atom loses electrons and tends to be electronically positive; moreover, a local electronic field can be formed around itself, inducing the adsorbed H2 molecules to be polarized. The polarized H2 molecules were found to be adsorbed by both the N and Al atoms, giving rise to the electrostatic attractions between the H2 molecules and the Al-doped g-CN surface. We found that each 2 × 2 supercell can adsorb at most, 24 H2 molecules, and the corresponding adsorption energies ranged from -0.11 to -0.31 eV. The highest hydrogen-storage capacity of the Al-doped g-CN can reach up to 6.15 wt%, surpassing the goal of 5.50 wt% proposed by the U.S. Department of Energy. Additionally, effective adsorption sites can be easily differentiated by the electronic potential distribution map of the optimized configurations. Such a composite material has been proven to possess a high potential for hydrogen storage, and we have good reasons to expect that in the future, more advanced materials can be developed based on this unit.

Xuedan Sustained Release Pellets Ameliorate Dextran Sulfate Sodium-Induced Ulcerative Colitis in Rats by Targeting Gut Microbiota and MAPK Signaling Pathways.

Cucurbitacins have a variety of bioactivities, such as anticancer, anti-inflammatory, antidepressant-like, and antiviral effects, but their pharmacological effect in ulcerative colitis (UC) has not been reported until now. Thus, this study aims to investigate the preventive effects of Xuedan sustained release pellets (XSPs) on UC rats and the underlying mechanisms. XSPs were prepared by extracting cucurbitacins from Hemsleya. Experimental UC rats were induced by the intake of 4% dextran sulfate sodium (DSS) for a week and treated with different doses of XSP (0.95, 1.90, and 3.8 mg/kg). The body weight, colon length, disease activity index (DAI), and histological changes of colonic tissue were measured. In addition, the expressions of pro-inflammatory cytokines were detected by using the enzyme-linked immunosorbent assay. Pathways involved in the intestinal inflammation were targeted by RNA-sequencing. Moreover, the changes of gut microbial diversity and composition were analyzed by the 16SrNA analysis and the contents of short-chain fatty acids (SCFAs) were detected by GC-MS. The results revealed that XSP intervention greatly restored the weight loss and colonic shortening (p < 0.05) and reduced the raised DAI scores, myeloperoxidase, and nitric oxide activities in UC in rats (p < 0.05). XSP administration also downregulated the protein levels of pro-inflammatory factors IL-1ß, IL-6, and TNF-α. Notably, it was found that XSP considerably suppressed the activation of the MAPK signaling pathway. In addition, XSP treatment improved the balance of gut microbiota that was disturbed by DSS. The beneficial bacteria Lachnospiraceae_NK4A136 group and Lactobacillus at the genus level significantly increased in the XSP group, which had decreased with the use of DSS (p < 0.05). Pathogenic bacteria including Escherichia-Shigella and Bacteroides in UC in rats were reduced by XSP intervention. Furthermore, XSP significantly elevated the production of SCFAs in UC in rats (p < 0.05). These alterations in inflammatory status were accompanied with changes in gut microbiota diversity and SCFA production. In conclusion, XSP exhibited protective effects against DSS-induced UC in rats. XSP treatment decreased inflammation via modulation of gut microbiota composition and SCFA production.

Comparative transcriptome analysis and identification of candidate genes involved in cucurbitacin IIa biosynthesis in Hemsleya macrosperma.

Hemsleya macrosperma (H. macrosperma) is widely used in southwestern China as folk medicine with various bioactivities. Cucurbitacin IIa is the main active component in H. macrosperma and draws increased attention for its potential pharmacological activities. In order to reveal the mechanism of cucurbitacin IIa biosynthesis and regulation in H. macrosperma, transcriptome analysis was performed to compare differentially expressed genes in three tissues (root tuber, stem and leaf). A total of 47 946 unigenes were generated from these tissues and 55 unigenes were identified as candidate genes involved in triterpenoid backbone biosynthesis. Three homologous genes encoding squalene epoxidase (HmSE) were discovered and successfully expressed in a prokaryotic system. HmSE1 was found to be responsible for oxidization of squalene. In addition, several cytochrome P450s and transcription factors were predicted as candidates associated to cucurbitacin IIa biosynthesis. Notably, the expression profiles of those putative genes showed a positive correlation with elevated curcurbitacin IIa production in methyl jasmonate-elicited suspension cells of H. macrosperma., suggesting probable functions of the candidates on curcurbitacin IIa biosynthesis. These findings provide insights on cucurbitacin IIa biosynthesis and regulation in H. macrosperma.

Viscosity Simulation of Glass Microfiber and an Unusual Air Filter with High-Efficiency Antibacterial Functionality Enabled by ZnO/Graphene-Modified Glass Microfiber.

The current global pandemic of new coronary pneumonia clearly reveals the importance of developing highly efficient filtration and fast germicidal performance of multifunctional air filters. In this study, a novel air filter with a controllable morphology based on the rod-like to flower-like zinc oxide/graphene-based photocatalytic composite particles loaded on glass microfiber was prepared by one-step microwave rapid synthesis. The multifunctional air filter shows the following special functions: the 10 mg·L-1 organic pollutant solution RhB was completely degraded within 2 h under a 500 W xenon lamp, and also 99% of Escherichia coli and Staphylococcus aureus were inactivated under a 60 W light-emitting diode lamp. Furthermore, after introducing the controllable morphology zinc oxide/graphene-based photocatalytic composite particles, the filtration efficiency of the multifunctional air filter was also kept at the same level (99.8%) as the one without any addition, indicating no loss of high-efficiency filtration while obtaining the rapid bactericidal function. The rapid antibacterial principle of the multifunctional air filter has also been proposed through the UV-vis spectroscopies, photoluminescence, and electron-spin resonance spectrum. The zinc oxide/graphene-based photocatalytic composite particles tightly coated on the glass microfiber surface could increase the active sites by changing the morphology of zinc oxide and, in the meantime, promote the separation of zinc oxide photo-generated electron-hole pairs to improve the rapid sterilization ability of the multifunctional air filters. In addition, an empirical formula to evaluate the relationship between the composition, viscosity, and viscosity modulus of glass microfiber was proposed by testing the viscosity of glass microfiber composed of 14 different compositions at 1300 and 1400 °C, which can be used as a criterion to evaluate the production technology of glass microfiber filters.

Grey Relational Analysis Combined With Network Pharmacology to Identify Antioxidant Components and Uncover Its Mechanism From Moutan Cortex.

The present study determines the potential antioxidants in Moutan Cortex (MC) and predicts its targets of anti-oxidative activities. The quantitative analysis and the free radical scavenging assays were conducted to detect the main components in MC and assess its anti-oxidant activities. The grey relational analysis and the network pharmacology approach were employed to predict its key components and targets of anti-oxidant activities. Six main constitutes in MCs were quantified by high performance liquid chromatography (HPLC) and its anti-oxidant activities were evaluated by DPPH and ABTS free radical scavenging methods. Then grey relational analysis was employed to predict the key components acting on anti-oxidative activity based on the chem-bio results. The predicted components and its mechanisms on anti-oxidation were uncovered by network pharmacology approach and cell test, respectively. The content of paeonol and paeoniflorin accounts for more than 80% the whole content of detected components. However, the two main ingredients showed a great variety among MCs. The antioxidant capacities of MCs also showed a great discrepancy based on DPPH and ABTS methods. The key components acting on anti-oxidation were identified to be paeonol, gallic acid and benzoylpaeoniflorin, and their potential therapeutic targets were predicted and verified, respectively. The present results reveal that MC has a significant antioxidant activity and the compounds of paeonol, gallic acid and benzoylpaeoniflorin could be considered as the promising antioxidant candidates with the property of suppressing oxidative stress and apoptosis.

A superfine glass fibre air filter with rapid response to photocatalytic antibacterial properties under visible light by loading rGO/ZnO.

The development of high-performance air filter has become more and more important to public health. However, it has always been very challenging for developing a multifunctional air filter to simultaneously achieve excellent filtration and antibacterial properties. Herein, a versatile air filter was prepared with loading the reduced graphene (rGO) and zinc oxide on the superfine glass fibre (s-GF) with the three-dimensional network structure by in situ sol-gel process followed by calcination, which aims to achieve synergistic high-efficiency air filtration and rapid response to photocatalytic antibacterial properties under visible light. The air filter showed a three-dimensional network structure based on a rGO/ZnO/s-GF multilayer and exhibited the highest catalytic performance by achieving a 95% degradation effect on rhodamine B within 2 h and achieving 100% antibacterial inactivation of the Escherichia coli and Staphylococcus aureus within 4 h under visible light when the weight ratio of rGO in rGO/ZnO is 1.6%. The air filtration efficiency can also be maintained at 99% after loading ZnO and rGO photocatalytic particles. The spectrum of the photoluminescence (PL), UV-Vis diffuse reflectance spectra (DRS) and electron spin resonance (ESR) indicate that the combination of rGO and ZnO on the s-GF can increase the separation of photogenerated carriers and the specific surface area of the air filter, thereby increasing the photocatalytic response and antibacterial properties of the s-GF air filter under visible light in a short time.

Phosphate modified hydrochars produced via phytic acid-assisted hydrothermal carbonization for efficient removal of U(VI), Pb(II) and Cd(II).

Phosphate species can complex with nuclides and heavy metals from aqueous solutions strongly. The introduction of phosphate groups onto the surface of biochar sorbents (mostly <1.0 at.% of P) is highly desired. In this study, phosphate modified hydrochars (HTBs) were prepared through the hydrothermal carbonization of bamboo sawdust with various duration (2, 12, 24 h) in the presence of phytic acid (0-70 wt%). The results showed that the addition of PA with a low concentration of 10 wt% carbonized at 2 h generated hydrogen protons to etch the pristine sawdust, inducing the granulation of surfaces and a 5.5-fold enhancement of surface area. While HTBs carbonized with increasing PA concentrations (30-70 wt%) and longer duration (12 and 24 h) presented more carbonaceous particles with rising sizes from <100 nm to 2.5 µm, which should be due to the cross-linkage of dehydrated phosphate-containing organic carbon components to the matrix, enabling the resultful surface modification (maximum of 2.1 wt% of P). The uptake of U(VI), Pb(II) and Cd(II) on HTBs was investigated given various geochemical conditions including contact time, pH, ionic strength, humic acid and temperature. HTBs could capture U(VI), Pb(II) and Cd(II) efficiently from the ideal and simulated wastewaters, and be reused well after six recycles. This work opened a new strategy for the potential of phosphate-hydrochars in the aqueous remediation.