Amorphization of MXenes: Boosting Electrocatalytic Hydrogen Evolution.

The emergence of amorphous 2D materials has opened up new avenue for materials science and nanotechnology in the recent years. Their unique disordered structure, excellent large-area uniformity, and low fabrication cost make them important for various industrial applications. However, there have no reports on the amorphous MXene materials. In this work, the amorphous Ti2C-MXene (a-Ti2C-MXene) model is built by ab initio molecular dynamics (AIMD) approach. This model is a unique amorphous model, which is totally different from continuous random network (CRN) model for silicate glass and amorphous model for amorphous 2D BN and graphene. The structure analysis shows that the a-Ti2C-MXene composited by [Ti5C] and [Ti6C] cluster, which are surrounded by the region of mixed cluster [TixC], [Ti-Ti] cluster, and [C-C] cluster. There is a high chemical activity for hydrogen evolution reaction (HER) in a-Ti2C-MXene with |ΔGH| 0.001 eV, implying that they serve as the potential boosting HER performance. The work provides insights that can pave the way for future research on novel MXene materials, leading to their increased applications in various fields.

Tailoring Advanced N-Defective and S-Doped g-C3 N4 for Photocatalytic H2 Evolution.

Although challenges remain, synergistic adjusting various microstructures and photo/electrochemical parameters of graphitic carbon nitride (g-C3 N4 ) in photocatalytic hydrogen evolution reaction (HER) are the keys to alleviating the energy crisis and environmental pollution. In this work, a novel nitrogen-defective and sulfur-doped g-C3 N4 (S-g-C3 N4 -D) is designed elaborately. Subsequent physical and chemical characterization proved that the developed S-g-C3 N4 -D not only displays well-defined 2D lamellar morphology with a large porosity and a high specific surface area but also has an efficient light utilization and carriers-separation and transfer. Moreover, the calculated optimal Gibbs free energy of adsorbed hydrogen (ΔGH* ) for S-g-C3 N4 -D at the S active sites is close to zero (≈0.24 eV) on the basis of first-principle density functional theory (DFT). Accordingly, the developed S-g-C3 N4 -D catalyst shows a high H2 evolution rate of 5651.5 µmol g-1  h-1 . Both DFT calculations and experimental results reveal that a memorable defective g-C3 N4 /S-doped g-C3 N4 step-scheme heterojunction is constructed between S-doped domains and N-defective domains in the structural configuration of S-g-C3 N4 -D. This work exhibits a significant guidance for the design and fabrication of high-efficiency photocatalysts.

Electrochemical Ammonia Synthesis via NO Reduction on 2D-MOF.

Developing new catalysts that effectively promote electrocatalytic NO reduction (ENOR) is a very important industrial field. A two-dimensional (2D) metal-organic framework (MOF) with hexaaminobenzene (HAB) ligands (TM-HAB MOF, TM=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh and Pd) as an electrocatalyst for ENOR was systematically explored in this work by means of well-defined density functional theory (DFT) calculations. We predicted the impact of the coordination structure of different MOFs on its catalytic performance and found that the suitable candidates are Co- and Rh-HAB MOFs due to moderate binding strength between NO and substrates. Further calculations indicated that Co-HAB MOF has the best ENOR catalytic activity with a limiting potential of - 0.26 V toward NH3 production at low NO coverage, yet NO reduction to N2 O at high NO coverage was limited due to high limiting potential. The scaling relationship with a good correlation coefficient between several electronic properties and the adsorption Gibbs free energy change of *NO (ΔG*NO ) were found, which implies that ΔG*NO can be used as a simple descriptor for screening out suitable electrocatalysts. This work offers a new paradigm for ENOR toward NH3 production under ambient conditions.

Activation of farnesoid X receptor downregulates monocyte chemoattractant protein-1 in murine macrophage.

Farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily, which plays important roles in bile acids/lipid homeostasis and inflammation. Monocyte chemoattractant protein-1 (MCP-1) contributes to macrophage infiltration into body tissues during inflammation. Here we investigated whether FXR can regulate MCP-1 expression in murine macrophage. FXR activation down regulate MCP-1 mRNA and protein levels in ANA-1 and Raw264.7 cells. Luciferase reporter assay, Gel shift and Chromatin immunoprecipitation assays have revealed that the activated FXR bind to the FXR element located in -738 bp âˆ¼  -723 bp in MCP-1 promoter. These results suggested that FXR may serve as a novel target for regulating MCP-1 levels for the inflammation related diseases therapies.

CL-SPO2Net: Contrastive Learning Spatiotemporal Attention Network for Non-Contact Video-Based SpO2 Estimation.

Video-based peripheral oxygen saturation (SpO2) estimation, utilizing solely RGB cameras, offers a non-contact approach to measuring blood oxygen levels. Previous studies set a stable and unchanging environment as the premise for non-contact blood oxygen estimation. Additionally, they utilized a small amount of labeled data for system training and learning. However, it is challenging to train optimal model parameters with a small dataset. The accuracy of blood oxygen detection is easily affected by ambient light and subject movement. To address these issues, this paper proposes a contrastive learning spatiotemporal attention network (CL-SPO2Net), an innovative semi-supervised network for video-based SpO2 estimation. Spatiotemporal similarities in remote photoplethysmography (rPPG) signals were found in video segments containing facial or hand regions. Subsequently, integrating deep neural networks with machine learning expertise enabled the estimation of SpO2. The method had good feasibility in the case of small-scale labeled datasets, with the mean absolute error between the camera and the reference pulse oximeter of 0.85% in the stable environment, 1.13% with lighting fluctuations, and 1.20% in the facial rotation situation.

Farnesoid X receptor up-regulates expression of lipid transfer inhibitor protein in liver cells and mice.

Apolipoprotein F is a component protein mainly secreted by liver and resides on several lipoprotein classes. It can inhibit lipids transfer between different lipoproteins. FXR is a member of the nuclear receptor superfamily which is also highly expressed in the liver. It modulates bile acids synthesis and lipids metabolism by transcriptional regulation. We aimed to determine whether apoF can be regulated by FXR. The FXR agonist Chenodeoxycholic acid (CDCA) and GW4064 both can activate the expression of apoF in liver cell lines and in C57/BL6 mouse liver. This is dependent on the binding of FXR to the FXR element ER1 (-2904 to -2892 bp) in the apoF gene promoter. Taken together, we have identified apoF as likely another target gene of FXR.

Amorphous MXene Opens New Perspectives.

Recently, novel amorphous nanomaterials formed by introducing atomic irregular arrangement factors have been successfully fabricated, showing superior performance in catalysis, energy storage, and mechanics. Among them, 2D amorphous nanomaterials are the stars, as they combine the benefits of both 2D structure and amorphous. Up to now, many research studies have been published on the study of 2D amorphous materials. However, as one of the most important parts of 2D materials, the research on MXenes mainly focuses on the crystalline counterpart, while the study of highly disordered forms is much less. This work will provide insight into the possibility of MXenes amorphization, and discusses the application prospect of amorphous MXenes materials.

Highly NH3 Sensitive and Selective Ti3C2O2-Based Gas Sensors: A Density Functional Theory-NEGF Study.

Ammonia (NH3) detection at the early stage is an important precaution for human health and agricultural production. However, conventional sensing materials are difficult to achieve all the targeted operational performances such as low power consumption and high selectivity. MXenes are a type of graphene-like emergent material equipped with abundant surface sites benefiting gas-sensing applications. In the work, we discuss the sensing performance of Ti3C2O2 to anticipate harmful and polluting NH3 gases by density functional theory and nonequilibrium Green's function. The adsorption geometry, charge difference density, and partial density of states are discussed to understand the nature of interactions between gas molecules and Ti3C2O2. The theoretical results show that only NH3 adsorbs onto the nanosheet through chemisorption. Then, a two-electrode Ti3C2O2-based gas sensor device is built to unravel the transport properties. Current under different bias voltages indicates the Ti3C2O2-based sensor could maintain extremely high sensitivity, demonstrating that Ti3C2O2 has great potential for the NH3 sensor with high selectivity, excellent sensitivity, and low energy consumption. Upon external electric fields, the adsorption energy and charge transfer can be tuned effectively, suggesting that Ti3C2O2 is a versatile agent as an ammonia-sensing material.

Charge-orbital synergistic engineering of TM@Ti3C2O1-xBx for highly selective CO2 electrochemical reduction.

Inspired by MXene nanosheets and their regulation of surface functional groups, a series of Ti3C2-MXene-based single TM atom electrocatalysts with a doped boron (B) atom (TM@Ti3C2O2-xBx, TM is V, Cr, Mn, Fe, Co or Ni, x = 0.11) are proposed for achieving a high performance catalytic CO2 reduction reaction (CO2RR). The results reveal that the doped B atom involves in the adsorption reaction of CO2 molecules and CO intermediates in the CO2RR. The TM-to-C and B-to-C π-back bonding contribute to the activation of the CO2 molecules and CO intermediates in the CO2RR. Enough electrons from the single TM atom and B atom occupied orbitals can be injected into the CO2 molecules and *CO intermediates through direct bonding interactions, which effectively alleviates the difficulty of the first hydrogenation reaction step and further helps CO reduction towards CH4. The calculated values of ΔG for the first hydrogenation reaction and the formation of *CHO on Ti3C2O2-xBx are significantly smaller than those of other single-atom catalysts (SACs). Fe@Ti3C2O2-xBx is found to have the highest electrocatalytic activity with a limiting potential of ∼0.40 V and exhibits a high selectivity for obtaining CH4 through the CO2RR compared with the hydrogen evolution reaction. This work is expected to open a research path for engineering the charge-orbital state of the innate atoms of a substrate based on mechanistic insights, which guides the rational design of highly selective MXene-based CO2RR electrocatalysts.

Effects of farnesoid X receptor on the expression of the fatty acid synthetase and hepatic lipase.

The farnesoid X receptor (FXR) is a nuclear receptor that regulates gene expression in response to bile acids (BAs). FXR plays an important role in the homeostasis of bile acid, cholesterol, lipoprotein and triglyceride. In this report, we identified fatty acid synthase (FAS) and hepatic lipase (HL) genes as novel target genes of FXR. Human hepatoma HepG2 cells were treated with chenodeoxycholic acid, the natural FXR ligand, and the messenger RNA and protein levels of FAS and HL were determined by RT-PCR and Western blot analysis, respectively. Chenodeoxycholic acid (CDCA) down-regulated the expression of FAS and HL genes in a dose and time-dependent manner in human hepatoma HepG2 cells. In addition, treatment of mice with CDCA significantly decreased the expression of FAS and HL in mouse liver and the activity of HL. These results demonstrated that FAS and HL might be FXR-regulated genes in liver cells. In view of the role of FAS and HL in lipogenesis and plasma lipoprotein metabolism, our results further support the central role of FXR in the homeostasis of fatty acid and lipid.

Unveiling the mechanism of high-performance hydrogen evolution reaction on noble-metal-free (113)-faceted Ni3C: ab initio calculations.

To examine the reactivity of noble-metal-free Ni3C towards hydrogen evolution reaction (HER), we report a comprehensive first-principles density functional theory (DFT) study on the stability, geometric structure, electronic characteristics, and catalytic activity for HER on the Ni3C crystal (113) surfaces with different surface terminations, namely the C-rich and Ni-rich terminated surface of Ni3C (113). The results indicate that C-rich and some stoichiometric surfaces are thermodynamically stable. The bridge-site of C-rich Ni3C (113) is indispensable for HER because it not only displays improved electrocatalytic activity, but also possesses appropriate hydrogen adsorption energy, overpotential and robust stability. The ΔG H (0.02 eV) and overpotential obtained by C-rich Ni3C outperformed that obtained by Pt determined by computation (ΔG H = -0.07 eV). Thus, the bridge-sites of C-rich Ni3C (113) function as both excellent and stable active sites and adsorption/desorption sites. Increasing the density of active sites through doping or enlarging the surface area renders a prospective strategy to ameliorate the HER activity further. Overall, this study elucidates new insights into the surface properties of Ni3C for HER from water splitting and opens up a fascinating avenue to optimize the performance of solar energy conversion devices by synthesizing preferentially exposed catalyst facets.

Regulations of the key mediators in inflammation and atherosclerosis by aspirin in human macrophages.

Although its role to prevent secondary cardiovascular complications has been well established, how acetyl salicylic acid (ASA, aspirin) regulates certain key molecules in the atherogenesis is still not known. Considering the role of matrix metalloproteinase-9 (MMP-9) to destabilize the atherosclerotic plaques, the roles of the scavenger receptor class BI (SR-BI) and ATP-binding cassette transporter A1 (ABCA1) to promote cholesterol efflux in the foam cells at the plaques, and the role of NF-kappaB in the overall inflammation related to the atherosclerosis, we addressed whether these molecules are all related to a common mechanism that may be regulated by acetyl salicylic acid. We investigated the effect of ASA to regulate the expressions and activities of these molecules in THP-1 macrophages. Our results showed that ASA inhibited MMP-9 mRNA expression, and caused the decrease in the MMP-9 activities from the cell culture supernatants. In addition, it inhibited the nuclear translocation of NF-kappaB p65 subunit, thus the activity of this inflammatory molecule. On the contrary, acetyl salicylic acid induced the expressions of ABCA1 and SR-BI, two molecules known to reduce the progression of atherosclerosis, at both mRNA and protein levels. It also stimulated the cholesterol efflux out of macrophages. These data suggest that acetyl salicylic acid may alleviate symptoms of atherosclerosis by two potential mechanisms: maintaining the plaque stability via inhibiting activities of inflammatory molecules MMP-9 and NF-kappaB, and increasing the cholesterol efflux through inducing expressions of ABCA1 and SR-BI.

Interleukin-1 up-regulates the expression and activity of 26S proteasome in burned rat.

Expression of IL-1 and proteasome are elevated in burned animals and patients. However, whether the increased level of IL-1 correlates with the increased activity and expression of 26S proteasome after burn has not been studied. In the present study, we investigated the role of single IL-1 factor on activation of the 26S proteasome first by injection of recombinant IL-1 into the normal rats. Results indicated that proteolytic activity and the expression of the 26S proteasome increased remarkably 24 and 48 h after-IL-1 injection, respectively. We then studied the potential role of IL-1 on activity and expression of the proteasome in the burned rat by using neutralizing monoclonal antibody against IL-1. Results demonstrated that activity and the expression of 26S proteasome were decreased partially but significantly 48 h after-burn when circulating IL-1 in injured animals was neutralized. These results indicate that IL-1 may play a key role on the activity and expression of 26S proteasome following burn. The proteasome has been verified as being deeply involved in the mechanism of accelerated muscle protein breakdown after burn, these results imply that IL-1 might be involved in the protein metabolism after-burn by activating the proteasome pathway, though protein metabolism directly affected by IL-1 had not been assessed in this study.

[The cloning, high level expression in Escherichia coli of human beta-defensin 3 and its antimicrobial activity analysis].

In recent years, Bacterial resistance is more and more serious for the irrational use of antibiotics produces resistant strains and other reasons. Human are trying to solve the problem from different ways, including the study of antimicrobial peptides. Defensin is one of the most important of antimicrobial peptides. A novel antimicrobial peptide, human beta-defensin 3, was isolated and demonstrated a salt-insensitive broad spectrum of potent antimicrobial activity against many potentially pathogenic microbes. The total RNA was extracted from human tonsil and the hbetaD-3 specific cDNA sequence was amplified with RT-PCR. After sequenced, the target DNA fragment was cloned into pQE-80L vector together with the DNA fragment encoding carrier protein DHFR. The recombinant vectors were transformed into E. coli M15 and the expression was induced based on the optimal values of the IPTG concentration incubation temperature and induction time determined in the previous section. The expressed proteins were analyzed by SDS-PAGE and Western-blotting. The mass of the recombinant protein was about 40% of total bacteria protein. Isolate and purify the target protein. The recombinant hbetaD-3 fusion proteins possess the antimicrobial activity to staphylococcus aureus, multiresistant staphylococcus aureus (only vancomycin-sensitive) and Candida albicans in the assay of drug susceptibility. Advanced study can be continued based on our experiments.