Latest ArticlesSperm damage caused by reactive oxygen species (ROS) is one of the main causes of male infertility. Therefore, the level of ROS in sperm is an important indicator for the diagnosis and prognosis of male infertility. Herein, we constructed a single sperm ROS detection method (SSRDM) with an optical micro-probe fabricated via focused ion beam process. The micro-probe is used to separately excite fluorescence in the sperm and the area around the sperm after ROS staining, and the difference in fluorescence values can reflect the level of ROS in the sperm. We collected 102 semen samples and 72 of them were divided into asthenozoospermia and non-asthenozoospermia groups. SSRDM and flow cytometry were used to detect the ROS levels of the two groups. The results of SSRDM showed that the ROS levels of asthenozoospermia group were higher than that of non-asthenozoospermia group (P = 0.002), while the results of flow cytometry indicated no difference (P = 0.152). In terms of ROS levels, compared with flow cytometry, SSRDM has a stronger ability to distinguish between those two groups, providing a reliable basis for assessment of sperm quality. Another 30 semen samples were used to investigate temperature and temporal variability of SSRDM to ensure the stability and accuracy of this method. Overall, we have developed a method that can quantitatively detect fluorescent substances in sperm at the single-cell level supplying evidence for diagnosis and prognosis of male infertility.
Photocatalytic fuel cell (PFC) holds great potential for the sustainable production of electricity and degradation of organic pollutants for solving global energy and environmental problems. However, the efficient photodegradation of organic dyes and antibiotic drugs, such as ciprofloxacin (CIP) and methylene blue (MB), remains challenging. Aiming at improving the separation efficiency of hole and electron for electricity generation in the PFC system, TiO2-NPs@NF-x photoanode was fabricated by a cost-effective and laborsaving hydrothermal approach. The as-fabricated photoanode demonstrated abundant active sites, enhanced light harvesting capacity and photogenerated charge carrier separation. At a CIP-HCl concentration of 10 mg/L and pH value of about 7, 85% of CIP-HCl can be efficiently removed after 3 h irradiation by 300 W Xe lamp. TiO2-NPs@NF-20 photoelectrode based PFC system exhibited an impressed ability to simultaneously degrade ciprofloxacin and generate electricity under light irradiation with an open circuit voltage of 1.021 V, short circuit current density and maximum power density of 2.4 mA/cm2, 0.357 mW/cm2, respectively. This work provided a cost-effective method for the treatment of organic waste and generation of electrical power.
Finding transition metal catalysts for effective catalytic conversion of CO to CO2 has attracted much attention. MXene as a new 2D layered material of early transition metal carbides, nitrides, and carbo-nitrides is a robust support for achoring metal atoms. In this study, the electronic structure, geometries, thermodynamic stability, and catalytic activity of MXene (Mo2CS2) supported single noble metal atoms (NM = Ru, Rh, Pd, Ir, Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations. First, AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo2CS2 monolayer. Three likely reaction pathways, Langmuir-Hinshelwood (LH), Eley-Rideal (ER), and Termolecular Eley–Rideal (TER) for CO oxidation on the Ru1- and Ir1@Mo2CS2 SACs, have been studied in detail. It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions. The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru1-OCO) and formation of OCO-Ir1-OCO intermediate. The downshift d-band center of Ru1- and Ir1@Mo2CS2 help to enhance activity and improve catalytst stability. Moreover, a microkinetic study predicts a maximum CO oxidation rate of 4.01 × 102 s-1 and 4.15 × 103 s-1 (298.15 K) following the TER pathway for the Ru1- and Ir1@Mo2CS2 catalysts, respectively. This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.
It is essential to develop efficient electrocatalysts to generate hydrogen from water electrolysis for hydrogen economy. In this work, platinum (Pt) and nickel (Ni) co-doped porous carbon nanofibers (Pt/Ni-PCNFs) with low Pt content were prepared via an electrospinning, carbonization and galvanic replacement reaction. Because of the high electrical conductivity, abundant electrochemical active sites and synergistic effect between Pt and Ni nanoparticles, the optimized Pt/Ni-PCNFs catalyst shows an excellent HER activity with overpotentials of 20 mV in 0.5 mol/L H2SO4 and 46 mV in 1 mol/L KOH at a current density of 10 mA/cm2. Furthermore, over 35-h long-term stability has been achieved without significant attenuation. This work provides a simple route to prepare highly efficient electrocatalysts for water splitting and has great prospects in the field of renewable energy.
Due to the high decay rate of the non-radiative transition of long wavelengths, the molecular design of efficient and stable near-infrared (NIR) electroluminescent materials remains a big challenge. Herein, a new tetradentate cyclometalated platinum(Ⅱ) complex with an N∧C∧C∧N coordinated framework has been developed and used as a dopant for NIR organic light-emitting diodes (OLEDs). The complex exhibited a short-lived (0.5–1.5 μs) metal-to-ligand charge transfer (MLCT) excited state in doped and neat films. The resulting NIR OLEDs (λEL = 730 nm) achieved maximum external quantum efficiency (EQEmax) of 5.2% and radiance of 74626 mW sr-1 m–2. Of note, the device exhibited excellent stability with operational lifetime of 119 h for LT90. This work demonstrated the great potential of tetradentate platinum(Ⅱ) complexes in the field of NIR OLEDs.
The morphology and heterojunction engineering are effective ways to boost the performance of Cu-based catalysts. Herein, we have reported the designed synthesis of two-dimensional Cu-CuO heterojunction nanosheets (2D Cu-CuO NS) based on 3-aminopropyl-triethoxysilane (APTES, KH550) aided synthetic strategy. The APTES can act as both the ligand and alkali (-OH) source to guide the large-scale synthesis of 2D Cu-based precursor, which can transform into 2D Cu-CuO NS by the controllable post-treatment. The Si species from APTES can protect the particles from the severe aggregation and growth, guaranteeing the formation of 2D sheets composed of small-sized Cu-CuO heterojunction (about 20 nm). The heterojunction interfaces can provide plentiful active sites to boost the catalytic ability. The 2D sheets can provide large accessible surface, being conducive to the contact of the catalyst and reactants. Benefiting from above virtues, the 2D Cu-CuO NS showed the superior catalytic performance for the reduction of a series of nitro compounds, being superior to most reported non-noble metal-based catalysts. Notably, it exhibited good re-cycled performance with no obvious performance degradation after 10 consecutive catalysis. The present study will be promising to promote the application of the Cu-based catalysts, due to its ability to control the morphology and potential for the large-scale synthesis.
Previous studies demonstrated that three-dimensional (3D) multicellular tumor spheroids (MCTS) could more closely mimic solid tumors than two-dimensional (2D) cancer cells in terms of the spatial structure, extracellular matrix-cell interaction, and gene expression pattern. However, no study has been reported on the differences in lipid metabolism and distribution among 2D cancer cells, MCTS, and solid tumors. Here, we used HepG2 liver cancer cell lines to establish these three cancer models. The variations of lipid profiles and spatial distribution among them were explored by using mass spectrometry-based lipidomics and matrix-assisted laser desorption/ionization mass spectrometry imaging (MSI). The results revealed that MCTS, relative to 2D cells, had more shared lipid species with solid tumors. Furthermore, MCTS contained more comparable characteristics than 2D cells to solid tumors with respect to the relative abundance of most lipid classes and mass spectra patterns. MSI data showed that 46 of 71 lipids had similar spatial distribution between solid tumors and MCTS, while lipids in 2D cells had no specific spatial distribution. Interestingly, most of detected lipid species in sphingolipids and glycerolipids preferred locating in the necrotic region to the proliferative region of solid tumors and MCTS. Taken together, our study provides the evidence of lipid metabolism and distribution demonstrating that MCTS are a more suitable in vitro model to mimic solid tumors, which may offer insights into tumor metabolism and microenvironment.
In order to realize the sulfur and water resistance and facilitate the CO oxidation reactions, the effects of strain on the adsorption of CO, O2, SO2 and H2O molecules on Ni single-atom-catalyst supported by single-carbon-vacancy graphene (Ni-SG) have been studied based on first principles calculations. It shows that the compressive strain increases the adsorption energies of all above mentioned molecules on Ni-SG, where SO2 is adsorbed more strongly on Ni-SG than CO. However, in the presence of tensile strain, the adsorption energies decreases significantly when the molecules (O2 and SO2) obtain electrons from Ni-SG, while the adsorption energies just slightly decrease when the molecules (CO and H2O) lose electrons to Ni-SG, which finally achieves the preferential adsorption of CO and O2 molecules on Ni-SG by tensile strain. In addition, with tensile strain increasing to 10%, the rate-limited energy barrier along Eley-Rideal (ER) path monotonically increases from 0.77 eV to 0.98 eV, while the rate-limited energy barrier along Langmuir-Hinshelwood (LH) path monotonically decreases from 0.54 eV to 0.44 eV, indicating that the tensile strain can facilitate the LH mechanism while imped the ER mechanism on Ni-SG. The Hirshfeld charge and orbital levels of O2 and CO molecules are modulated by the tensile strain, which plays an important role for the decreasing of energy barriers for CO oxidation. Overall, the tensile strain can enhance the sulfur and water resistance of Ni-SG, as well as boost the CO oxidation reactions.
A series of monolithic MnO2/iron mesh (IM) catalysts for oxidation of toluene were successfully prepared by using in situ hydrothermal growth. MnO2 can grow firmly on the IM substrates surface with a shedding rate of only 0.14%. Due to the highest Oads and high-valent Mn4+ and Fe3+ elements, the temperature at 50% and 90% toluene conversion (T50% and T90%) was 252 and 265 ℃, respectively for the best performance catalyst (hydrothermal temperature of 80 ℃, hydrothermal time of 12 h, and precursor manganese ion concentration of 0.03 mol/L). The catalysts also presented good water resistance and cycle performance. In-situ DRIFTS results suggesting that toluene was first rapid transformed into the reaction intermediate species (benzoate species) and then converted to CO2 and H2O. Therefore, this work provides a new direction for the research and application of IM-based monolithic catalysts.
Pyrogenic carbonaceous matter (PCM) catalyzes azo dye decolorization by sulfide, but the nitrogen doping catalytic mechanisms are poorly understood. In this study, we found that stagnate time of azo dye methyl orange (MO) decolorization was reduced to 0.54-18.28 min in the presence of various nitrogen-doped graphenes (NGs), remarkably lower compared to graphene itself. Particularly, graphitic nitrogen played a critical role in NGs-catalyzed MO decolorization by sulfide. Gas chromatography-mass spectrometry and in-situ surface Raman analysis demonstrated that doping nitrogen, especially graphite one facilitated reactive intermediate polysulfides formation. This is attributed to the improved electron conductivity through graphitic nitrogen doping, and the enhanced interactions between sulfide and carbon atoms bonded to graphitic nitrogen. This study not only provides a better understanding of PCM impact on transformations and fates of organic pollutants in natural environments, but also offer a new regulation strategy for more efficient wastewater treatment processes in PCM-catalyzed engineering systems.
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