Ni‐promoted electrocatalytic biomass reforming has shown promising prospect in enabling high value‐added product synthesis. Here, we developed a novel hybrid catalyst with Ni nanosheet forests ...anchored on carbon paper. The hybrid catalyst exhibits high efficiency in electrooxidation of HMF to FDCA coupling with H2 production in high purity. The Ni nanosheets have small crystal grain sizes with abundant edges, which is able to deliver an efficient HMF oxidation to FDCA (selectivity >99 %) at low potential of 1.36 VRHE with high stability. The post‐reaction structure analysis reveals the Ni nanosheets would transfer electrons to carbon and readily turn into NiOx and Ni(OH)x during the reaction. DFT results suggest high valence Ni species would facilitate the chemical adsorption (activation) of HMF revealing the reaction pathway. This work emphasizes the importance of the precise control of Ni activity via atomic structure engineering.
Highly efficient and stable electro‐reforming of HMF into FDCA on a Ni nanosheet/carbon paper electrode is achieved at a potential of 1.36 VRHE with 99.7 % conversion. A precursor‐limiting electrodeposition method creates a unique Ni nanosheet forest structure with vastly different physical appearance and catalytic activity comparing with conventional Ni catalysts.
A considerable amount of platinum (Pt) is required to ensure an adequate rate for the oxygen reduction reaction (ORR) in fuel cells and metal‐air batteries. Thus, the implementation of atomic Pt ...catalysts holds promise for minimizing the Pt content. In this contribution, atomic Pt sites with nitrogen (N) and phosphorus (P) co‐coordination on a carbon matrix (PtNPC) are conceptually predicted and experimentally developed to alter the d‐band center of Pt, thereby promoting the intrinsic ORR activity. PtNPC with a record‐low Pt content (≈0.026 wt %) consequently shows a benchmark‐comparable activity for ORR with an onset of 1.0 VRHE and half‐wave potential of 0.85 VRHE. It also features a high stability in 15 000‐cycle tests and a superior turnover frequency of 6.80 s−1 at 0.9 VRHE. Damjanovic kinetics analysis reveals a tuned ORR kinetics of PtNPC from a mixed 2/4‐electron to a predominately 4‐electron route. It is discovered that coordinated P species significantly shifts d‐band center of Pt atoms, accounting for the exceptional performance of PtNPC.
Phosphorus‐coordinated atomic Pt‐Nx sites are theoretically predicted and experimentally realized, offering enhanced kinetics for four‐electron electrochemical oxygen reduction. Exceptional activity is attributed to the tuning of the d‐band electron center via local coordination asymmetry. This chemistry provides an effective guideline for atomic Pt catalysts in batteries and fuel cells.
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•A low-cost adsorbent was successfully prepared and had high capacity for removing Cd(II).•Adsorbent characterizations were investigated using modern instrument analytical ...technique.•pH was the most critical factor affecting the removal of Cd(II).•Adsorption kinetic, equilibrium and thermodynamicaspects were examined.•Cd(II) removal mechanism was investigated.
In this work, the original and modified steel-making slags were tested to remove of Cd(II) ions from acidic aqueous solution. The physicochemical characteristics of the materials were investigated to understand the effect of surface properties on the Cd(II) adsorption behavior. The effects of contact time, pH, adsorbent dosage and temperature on adsorption process were studied in batch experiments. The results showed that the adsorption capacity of modified steel-making slag was found to sharply increase as a result of modification, and the adsorbent has excellent acid neutralization capacity. The optimum condition for removal was found to be 10g/L adsorbent on the treatment of 100mg/L Cd(II) at pH 4.0, and the Cd(II) removal rate could reach 99.1%. Kinetic data were best described by pseudo-second-order model. The adsorption isotherms were good fit to the Langmuir model with a maximum adsorption capacity of 10.16mg/g at 25°C. The thermodynamic studies indicated that the adsorption was a spontaneous and endothermic process. It was concluded that the mechanism of Cd(II) removal by modified steel-making slag is mainly based on chemisorptions including chemical precipitation and coordination reactions.
Metastasis is a major cause of death in patients with breast cancer. In the process of cancer development, epithelial-mesenchymal transition (EMT) is crucial to promoting the invasion and migration ...of tumor cells. In a previous study, the role of resveratrol in migration and metastasis was investigated in MDA-MB-231 (MDA231) human breast cancer cells and a xenograft-bearing mouse model. Additionally, the related mechanism was explored. In the present study, in vitro Transwell assays showed that resveratrol can inhibit the migration of transforming growth factor (TGF)-β1-induced MDA231 cells in a concentration-dependent manner. An enzyme-linked immunosorbent assay (ELISA) showed that resveratrol can reduce the secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Immunofluorescence was performed to confirm the expression of EMT-related markers. Immunofluorescence assays confirmed that resveratrol changed the expression of the EMT-related markers E-cadherin and vimentin. Western blot analysis demonstrated that resveratrol decreased the expression levels of MMP-2, MMP-9, Fibronectin, α-SMA, P-PI3K, P-AKT, Smad2, Smad3, P-Smad2, P-Smad3, vimentin, Snail1, and Slug, as well as increased the expression levels of E-cadherin in MDA231 cells. In vivo, resveratrol inhibited lung metastasis in a mouse model bearing MDA231 human breast cancer xenografts without marked changes in body weight or liver and kidney function. These results indicate that resveratrol inhibits the migration of MDA231 cells by reversing TGF-β1-induced EMT and inhibits the lung metastasis of MDA231 human breast cancer in a xenograft-bearing mouse model.
In this paper, the Hawking–Page phase transitions between the black holes and thermal anti-de Sitter (AdS) space are studied with the Gauss–Bonnet term in the extended phase space, in which the ...varying cosmological constant plays the role of an effective thermodynamic pressure. The Gauss–Bonnet term exhibits its effects via introducing the corrections to the black hole entropy and Gibbs free energy. The global phase structures, especially the phase transition temperature
T
HP
and the Gibbs free energy
G
, are systematically investigated, first for the Schwarzschild–AdS black holes and then for the charged and rotating AdS black holes in the grand canonical ensembles, with both analytical and numerical methods. It is found that there are terminal points in the coexistence lines, and
T
HP
decreases at large electric potentials and angular velocities and also decreases with the Gauss–Bonnet coupling constant
α
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Encapsulating metal‐based catalysts inside carbon sheaths is a frequently‐adopted strategy to enhance their durability under various harsh situations and improve their catalytic activity ...simultaneously. Such carbon encapsulation, however, imposes significant complications for directly modifying materials’ surface atomic/electronic configurations, fundamentally impeding the accurate tuning of their catalytic capabilities. Herein, a universal single‐atom alloy (SAA) strategy is reported to indirectly yet precisely manipulate the surface electronic structure of carbon‐encapsulated electrocatalysts. By versatilely constructing a SAA core inside an N‐doped carbon sheath, material's electrocatalytic capability can be flexibly tuned. The one with Ru‐SAA cores serves as an excellent bifunctional electrocatalyst for oxygen/hydrogen evolution, exhibiting minimal cell voltage of 1.55 V (10 mA cm−2) and outstanding mass activity of 1251 mA mgRu−1${\rm{g}}_{{\rm{Ru}}}^{ - 1}$ for overall water splitting, while the one with Ir‐SAA cores possesses superior oxygen reduction activity with a half‐wave potential of 919 mV. Density functional theory calculations reveal that the doped atoms can simultaneously optimize the adsorption of protons (H*) and oxygenated intermediates (OH*, O*, and OOH*) to achieve the remarkable thermoneutral hydrogen evolution and enhanced oxygen evolution. This work thus demonstrates a versatile strategy to precisely modify the surface electronic properties of carbon‐shielded materials for optimized performances.
A universal single‐atom alloy strategy is proposed to precisely manipulate the surface electronic structure of carbon‐encapsulated electrocatalysts, thus simultaneously achieving the catalytic multifunctionality, catalytic activity promotion, and durability maintenance. Theoretical calculation discloses the relationship among various single atoms, surface electronic structures, and the resulted electrocatalytic hydrogen/oxygen evolution behavior. This study demonstrates a versatile strategy to precisely modify the surface electronic properties of carbon‐shielded materials for optimized performances.
The Hawking–Page phase transitions of the d-dimensional Schwarzschild and charged black holes are explored in a cavity. The phase transition temperature THP, the minimum black hole temperature T0, ...and the Gibbs free energy G are systematically calculated. A dual relation for the Schwarzschild black holes in the anti-de Sitter space, THP(d)=T0(d+1), is found to be also approximately valid in the cavity case to a high precision, and this relation can be further generalized to the charged black holes in a suitable form. Our work reveals the universal properties of the black holes in different extended phase spaces and motivates further studies on their thermodynamic behaviors that are sensitive to specific boundary conditions, like the terminal points in the G–T curves.
A novel halophilic bacterium capable of heterotrophic nitrification-aerobic denitrification was isolated from marine sediments and identified as Vibrio diabolicus SF16. It had ability to remove ...91.82% of NH4(+)-N (119.77 mg/L) and 99.71% of NO3(-)-N (136.43 mg/L). The nitrogen balance showed that 35.83% of initial NH4(+)-N (119.77 mg/L) was changed to intracellular nitrogen, and 53.98% of the initial NH4(+)-N was converted to gaseous denitrification products. The existence of napA gene further proved the aerobic denitrification ability of strain SF16. The optimum culture conditions were salinity 1-5%, sodium acetate as carbon source, C/N 10, and pH 7.5-9.5. When an aerated biological filter system inoculated with strain SF16 was employed to treat saline wastewater, the average removal efficiency of NH4(+)-N and TN reached 97.14% and 73.92%, respectively, indicating great potential of strain SF16 for future full-scale applications.
The epithelial-to-mesenchymal transition (EMT) plays a prominent role in cancer metastasis. Isoliquiritigenin (ISL), one of the flavonoids in licorice, has been shown to exhibit anticancer activities ...in many cancer types through various mechanisms. However, it is unknown whether ISL impacts the EMT process. Here, we show that ISL is able to suppress mesenchymal features of ovarian cancer SKOV3 and OVCAR5 cells, evidenced by an apparent morphological change from a mesenchymal to an epithelial phenotype and reduced levels of mesenchymal markers accompanied by the gain of E-cadherin expression. The suppression of EMT is also supported by the observed decrease in cell migration and in vitro invasion upon ISL treatment. Moreover, we show that ISL effectively blocks the intraperitoneal xenograft development of the SKOV3 cell line and prolonged the survival of tumor-bearing mice. These data suggest that ISL inhibits intraperitoneal ovary tumor development through the suppression of EMT, indicating that ISL may be an effective therapeutic agent against ovarian cancer.
The primordial black hole (PBH) is an effective candidate for dark matter. In this work, the PBH abundance f is calculated in peak theory, with one or two perturbations in the inflaton potential. We ...construct an antisymmetric perturbation that can create a perfect plateau in the inflaton potential, leading inflation to the ultraslow-roll stage. During this stage, the power spectrum of primordial curvature perturbation is remarkably enhanced on small scales, generating abundant PBHs. The PBH abundance f ~ 0.1 can be achieved in one or two typical mass windows at 10−17 M⊙, 10−13 M⊙, and 30 M⊙, without spoiling the nearly scale-invariant power spectrum on large scales. For comparison, f is calculated in two approximate methods of peak theory (with different spectral moments) and also in the Press-Schechter theory. It is found that the Press-Schechter theory systematically underestimates f by 2 or 3 orders of magnitude compared with peak theory.
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