Facet-switching of rate-determining step on copper in CO2-to-ethylene electroreduction.

Reduction of carbon dioxide (CO2) by renewable electricity to produce multicarbon chemicals, such as ethylene (C2H4), continues to be a challenge because of insufficient Faradaic efficiency, low production rates, and complex mechanistic pathways. Here, we report that the rate-determining steps (RDS) on common copper (Cu) surfaces diverge in CO2 electroreduction, leading to distinct catalytic performances. Through a combination of experimental and computational studies, we reveal that C─C bond-making is the RDS on Cu(100), whereas the protonation of *CO with adsorbed water becomes rate-limiting on Cu(111) with a higher energy barrier. On an oxide-derived Cu(100)-dominant Cu catalyst, we reach a high C2H4 Faradaic efficiency of 72%, partial current density of 359 mA cm-2, and long-term stability exceeding 100 h at 500 mA cm-2, greatly outperforming its Cu(111)-rich counterpart. We further demonstrate constant C2H4 selectivity of >60% over 70 h in a membrane electrode assembly electrolyzer with a full-cell energy efficiency of 23.4%.

Plasma-Assisted Synthesis of Metal Nitrides for an Efficient Platinum-Group-Metal-Free Anion-Exchange-Membrane Fuel Cell.

In comparison to the well-developed proton-exchange-membrane fuel cells, anion-exchange-membrane fuel cells (AEMFCs) permit adoption of platinum-group-metal (PGM)-free catalysts due to the alkaline environment, giving a substantial cost reduction. However, previous AEMFCs have generally shown unsatisfactory performances due to the lack of effective PGM-free catalysts that can endure harsh fuel cell conditions. Here we report a plasma-assisted synthesis of high-quality nickel nitride (Ni3N) and zirconium nitride (ZrN) employing dinitrogen as the nitrogen resource, exhibiting exceptional catalytic performances toward hydrogen oxidation and oxygen reduction in an alkaline enviroment, respectively. A PGM-free AEMFC assembled by using Ni3N as the anode and ZrN as the cathode delivers power densities of 256 mW cm-2 under an H2-O2 condition and 151 mW cm-2 under an H2-air condition. Furthermore, the fuel cell shows no evidence of degradation after 25 h of operation. This work creates opportunities for developing high-performance and durable AEMFCs based on metal nitrides.

Unraveling Stoichiometry Effect in Nickel-Tungsten Alloys for Efficient Hydrogen Oxidation Catalysis in Alkaline Electrolytes.

Anion-exchange membrane fuel cells provide the possibility to use platinum group metal-free catalysts, but the anodic hydrogen oxidation reaction (HOR) suffers from sluggish kinetics and its source is still debated. Here, over nickel-tungsten (Ni-W) alloy catalysts, we show that the Ni : W ratio greatly governs the HOR performance in alkaline electrolyte. Experimental and theoretical studies unravel that alloying with W can tune the unpaired electrons in Ni, tailoring the potential of zero charge and the catalytic surface to favor hydroxyl adsorption (OHad). The OHad species coordinately interact with potassium (K+) ions, which break the K+ solvation sheath to leave free water molecules, yielding an improved connectivity of hydrogen-bond networks. Consequently, the optimal Ni17W3 alloy exhibits alkaline HOR activity superior to the state-of-the-art platinum on carbon (Pt/C) catalyst and operates steadily with negligible decay after 10,000 cycles. Our findings offer new understandings of alloyed HOR catalysts and will guide rational design of next-generation catalysts for fuel cells.

Efficient NH3-Tolerant Nickel-Based Hydrogen Oxidation Catalyst for Anion Exchange Membrane Fuel Cells.

Converting hydrogen chemical energy into electrical energy by fuel cells offers high efficiencies and environmental advantages, but ultrapure hydrogen (over 99.97%) is required; otherwise, the electrode catalysts, typically platinum on carbon (Pt/C), will be poisoned by impurity gases such as ammonia (NH3). Here we demonstrate remarkable NH3 resistivity over a nickel-molybdenum alloy (MoNi4) modulated by chromium (Cr) dopants. The resultant Cr-MoNi4 exhibits high activity toward alkaline hydrogen oxidation and can undergo 10,000 cycles without apparent activity decay in the presence of 2 ppm of NH3. Furthermore, a fuel cell assembled with this catalyst retains 95% of the initial peak power density even when NH3 (10 ppm)/H2 was fed, whereas the power output reduces to 61% of the initial value for the Pt/C catalyst. Experimental and theoretical studies reveal that the Cr modifier not only creates electron-rich states that restrain lone-pair electron donation but also downshifts the d-band center to suppress d-electron back-donation, synergistically weakening NH3 adsorption.

Suppressing Electron Back-Donation for a Highly CO-tolerant Fuel Cell Anode Catalyst via Cobalt Modulation.

Platinum on carbon (Pt/C) catalyst is commercially adopted in fuel cells but it undergoes formidable active-site poisoning by carbon monoxide (CO). In particular, given the sluggish kinetics of hydrogen oxidation reaction (HOR) in anion-exchange membrane fuel cell (AEMFC), the issues of Pt poisoning and slow rate would combine mutually, notably worsening the device performances. Here we overcome these challenges through incorporating cobalt (Co) into molybdenum-nickel alloy (MoNi4 ), termed Co-MoNi4 , which not only shows superior HOR activity over the Pt/C catalyst in alkali, but more intriguingly exhibits excellent CO tolerance with only small activity decay after 10 000 cycles in the presence of 500 parts per million (ppm) CO. When feeding with CO (250 ppm)/H2 , the AEMFC assembled by this catalyst yields a peak power density of 394 mW cm-2 , far exceeding the Pt/C catalyst. Experimental and computational studies reveal that weakened CO chemisorption originates from the electron-deficient Ni sites after Co incorporation that suppresses d→CO 2π* back-donation.

Efficient acidic hydrogen evolution in proton exchange membrane electrolyzers over a sulfur-doped marcasite-type electrocatalyst.

Large-scale deployment of proton exchange membrane (PEM) water electrolyzers has to overcome a cost barrier resulting from the exclusive adoption of platinum group metal (PGM) catalysts. Ideally, carbon-supported platinum used at cathode should be replaced with PGM-free catalysts, but they often undergo insufficient activity and stability subjecting to corrosive acidic conditions. Inspired by marcasite existed under acidic environments in nature, we report a sulfur doping-driven structural transformation from pyrite-type cobalt diselenide to pure marcasite counterpart. The resultant catalyst drives hydrogen evolution reaction with low overpotential of 67 millivolts at 10 milliamperes per square centimeter and exhibits no degradation after 1000 hours of testing in acid. Moreover, a PEM electrolyzer with this catalyst as cathode runs stably over 410 hours at 1 ampere per square centimeter and 60°C. The marked properties arise from sulfur doping that not only triggers formation of acid-resistant marcasite structure but also tailors electronic states (e.g., work function) for improved hydrogen diffusion and electrocatalysis.

Correction: Polysaccharides from Ulva prolifera O.F. Müller inhibit cell proliferation via activating MAPK signaling in A549 and H1650 cells.

Correction for 'Polysaccharides from Ulva prolifera O.F. Müller inhibit cell proliferation via activating MAPK signaling in A549 and H1650 cells' by Juan Juan Yang et al., Food Funct., 2021, 12, 6915-6924, https://doi.org/10.1039/D1FO00294E.

Sortilin regulates keratinocyte proliferation and apoptosis through the PI3K-AKT signaling pathway.

Sortilin is found to regulate proliferation and death of different cells, while its role in regulating keratinocyte proliferation and apoptosis is still unknown. In this study, we found that sortilin levels significantly increased in psoriasis patients, and sortilin suppression eliminated the proliferation of HaCaT cells induced by M5 cocktail solution and enhanced the levels of cleaved caspase 3 protein and the Bax/Bcl-2 ratio; however, levels of p-PI3K and p-AKT were decreased. In addition, sortilin silencing remitted the characteristic changes associated with psoriasis-like skin lesions. In summary, suppressed sortilin expression helped inhibit keratinocyte proliferation in HaCaT cells by inactivating PI3K/AKT signaling, which provides a new target for the therapy of psoriasis.

Polysaccharides from Ulva prolifera O.F. Müller inhibit cell proliferation via activating MAPK signaling in A549 and H1650 cells.

Reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), have recently been reported to cause a significant increase in the production and expression of matrix metalloproteinases (MMPs), which are closely correlated with lung cancer metastasis. The aim of the present study is to determine the inhibitory effects of a polysaccharide isolated from Ulva prolifera O.F. Müller (U. prolifera) on the invasive potential of non-small cell lung cancer (NSCLC) cells, and further to explore the underlying mechanisms connected to that potential. The data showed that increased MMP-9 resulting from H2O2 exposure was mediated by activating mitogen-activated protein kinases (MAPKs). Pre-treatment with polysaccharides suppressed the activation of H2O2-mediated MAPK pathways and cell invasion. Hence, MMP-9 production triggered by H2O2 was demonstrated by activating MAPK signaling in a Myc-dependent manner. Taken together, these results suggested that polysaccharides suppress H2O2-induced cell invasion by inhibiting Myc-mediated MMP-9 gene transcription through the MAPK signaling pathway in A549 and NCI-H1650 cells. Our data also suggested that polysaccharides may be useful in minimizing the development of lung cancer metastasis. In the future, pretreatment with polysaccharides because of their antioxidant properties might be beneficial to enhance surgical outcomes.

[The application of fluorescence in situ hybridization and automated image cytometry in the diagnosis of urothelial carcinoma of bladder].

OBJECTIVE: To discuss the application of automated DNA image cytometry (ICM) and fluorescence in situ hybridization (FISH) in the diagnosis of urothelial carcinoma of bladder. METHODS: From August 2008 to March 2009, 60 volunteers with informed consent were divided into two groups, 40 patients proven as urothelial carcinoma of bladder by pathology and 20 healthy individuals as control. Urine was collected and tested by cytology, ICM and FISH. RESULTS: Overall sensitivity of FISH was significantly higher in detection of malignancy than that of ICM (82.5% vs 62.5%, P < 0.05) and that of urine cytology (82.5% vs 25.0%, P < 0.05), while ICM was more sensitive to diagnose urothelial carcinoma of bladder than urine cytology (62.5% vs 25.0%, P < 0.05). Specificities of urine cytology, ICM and FISH were 100% in diagnosis of urothelial carcinoma of bladder (P > 0.05). Sensitivities of urine cytology, ICM and FISH have no correlation with pathological stage (P > 0.05), but have significant correlation with grade (P < 0.05). CONCLUSIONS: ICM and FISH have the same specificity as urine cytology in diagnosis of urothelial carcinoma of bladder, but they have significantly higher sensitivity than urine cytology. FISH has the highest sensitivity among three diagnostic methods. Therefore, FISH may become a newly non-invasive technique for the diagnosis and surveillance of urothelial carcinoma of bladder.

[Significance and role of increased expression of extracellular matrix metalloproteinase induced in the aseptic loosening of prostheses].

OBJECTIVE: To investigate the expression of extracellular matrix metalloproteinase induced (EMMPRIN) in the interface tissue, and explore the role of EMMPRIN in the aseptic loosening of prostheses. METHODS: Immunohistochemistry was performed to characterize the EMMPRIN-expressing cells at sites of interface tissue around aseptic loosened hip prostheses in 16 cases. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to study the existence of EMMPRIN mRNA in interface tissue samples. And it was followed up by computer assisted image analysis in order to detect the A values of their expression. Synovium of hip joint of 8 femoral neck fracture were in control group. RESULTS: Strong immunostaining of EMMPRIN was found in the macrophages and fibroblasts of lining-like layers and vascular endothelium of synovial membrane-like interface tissue around loosened prostheses. Expression of EMMPRIN was significantly higher in interface tissue than the control synovium (z=-3.252, P=0.001). RT-PCR of interface tissue samples disclosed the presence of EMMPRIN mRNA of 14 cases. In interface tissue, the A value of EMMPRIN increased significantly compared to control synovium (P<0.01). CONCLUSION: Over-expression of EMMPRIN up-regulates the production of matrix metalloproteinase (MMPs) in the interface tissue. And it can promote the bone destruction around prostheses. Thereby it may be one of methods to prevent and treat aseptic loosening of prostheses by repression the biology activity of EMMPRIN.