Progesterone promotes neuronal differentiation of human umbilical cord mesenchymal stem cells in culture conditions that mimic the brain microenvironment

In this study, human umbilical cord mesenchymal stem cells from full-term neonates born by vagina delivery were cultured in medium containing 150 mg/mL of brain tissue extracts from Sprague-Dawley rats （to mimic the brain microenvironment）. Immunocytochemical analysis demonstrated that the cells differentiated into neuron-like cells. To evaluate the effects of progesterone as a neurosteroid on the neuronal differentiation of human umbilical cord mesenchymal stem cells, we cultured the cells in medium containing progesterone （0.1, 1, 10 pM） in addition to brain tissue extracts. Reverse transcription-PCR and flow cytometric analysis of neuron specific enolase-positive cells revealed that the percentages of these cells increased significantly following progesterone treatment, with the optimal progesterone concentration for neuron-like differentiation being 1 tJM. These results suggest that progesterone can enhance the neuronal differentiation of human umbilical cord mesenchymal stem cells in culture medium containing brain tissue extracts to mimic the brain microenvironment.

Recent Advances on MOF Derivatives for Non-Noble Metal Oxygen Electrocatalysts in Zinc-Air Batteries

Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries(ZABs).Owing to the high specific surface area,controllable pore size and unsaturated metal active sites,metal-organic frameworks(MOFs)derivatives have been widely studied as oxygen electrocatalysts in ZABs.To date,many strategies have been developed to generate efficient oxygen electrocatalysts from MOFs for improving the performance of ZABs.In this review,the latest progress of the MOF-derived non-noble metal-oxygen electrocatalysts in ZABs is reviewed.The performance of these MOF-derived catalysts toward oxygen reduction,and oxygen evolution reactions is discussed based on the categories of metal-free carbon materials,single-atom catalysts,metal cluster/carbon composites and metal compound/carbon composites.Moreover,we provide a comprehensive overview on the design strategies of various MOF-derived non-noble metal-oxygen electrocatalysts and their structure-performance relationship.Finally,the challenges and perspectives are provided for further advancing the MOF-derived oxygen electrocatalysts in ZABs.

Ti_(3)C_(2)T_(x)MXene wrapped,carbon-coated porous Si sheets for improved lithium storage performance

Si-based materials have shown great potential as lithium-ion batteries(LIBs)anodes due to their natural reserves and high theoretical capacity.However,the large volume changes during cycles and poor conductivity of Si lead to rapid capacity decay and poor cycling stability,ultimately limiting their commercial applications.Herein,we have skillfully utilized the microporous MCM-22 zeolite as the unique silicon source to produce porous Si(pSi)sheets by a simple magnesiothermic reduction,followed by a carbon coating and further Ti_(3)C_(2)T_(x)MXene assembly,obtaining the ternary pSi@NC@TNSs composite.In the design,porous Si sheets provide more active sites and shorten Li-ion transport paths for electrochemical reactions.The N-doped carbon(NC)layer serves as a bonding layer to couple pSi and Ti_(3)C_(2)T_(x).The conductive network formed by 2D Ti_(3)C_(2)T_(x)and medium NC layer effectively enhances the overall charge transport of the electrode material,and helps to stabilize the electrode structure.Therefore,the as-made pSi@NC@TNSs anode delivers an improved lithium storage performance,exhibiting a high reversible capacity of 925 mAh/g at 0.5 A/g after 100 cycles.This present strategy provides an effective way towards high-performance Si-based anodes for LIBs.

In-situ transformed trimetallic metal-organic frameworks as an efficient pre-catalyst for electrocatalytic oxygen evolution

Developing high-efficiency and low-cost oxygen evolution reaction(OER)catalysts is crucial to advance the water splitting technology for sustainable hydrogen production.Here,a FeCoNi coordinated benzene-1,3,5-tricarboxylic acid(FeCoNiBTC)metal-organic framework(MOF)was synthesized by one-step solvothermal method for OER.A rapid in-situ chemical and electrochemical transformation was observed on the surface of the FeCoNiBTC MOF during OER process.The formed catalytic active FeCoNiOx(OH)y species retained the unique structure feature of initial FeCoNiBTC,moreover,it possessed multiple transition metal active nodes that cooperate with each other to adjust the electronic structure.Owing to the above structure advantages,the in-situ transformed FeCoNiOx(OH)y showed excellent OER catalytic activity with a small overpotential of 230 mV to achieve the 100 mA·cm^(−2),a low Tafel slope of 50.2 mV·dec^(−1),and superior stability of almost 80 h in alkaline aqueous solution.This work systematically studies the structure-performance relations of the multi-metal MOF-based materials in OER process,and it would enrich the exploration of highly efficient OER electrocatalysts.

Porous 2D CuO nanosheets for efficient triethylamine detection at low temperature

The freshness of seafood can be judged by detecting the concentration of triethylamine(TEA). In this work, 2D Cu O porous nanosheets(Cu O PNs) were prepared by a graphene oxide template method and their particle sizes were regulated by changing the calcination temperature. Their structure, morphology and gas sensing performances were investigated by various characterization methods. The response(Rg/Ra) of the gas sensor based on Cu O PNs calcined at 700oC was as high as 440-100 ppm TEA at the operating temperature of 40 ℃. The detection limit was as low as 0.25 ppm. In addition, the gas sensor has good selectivity and stability. The excellent TEA sensitivity is mainly resulted from the appropriate particle size and loose porous framework. This work not only paves the way to explore the novel low temperature TEA gas sensors, but also provides deep insight on improving the structure and properties of gas sensitive materials by controlling the calcination temperature.

Preparation of two-dimensional molybdenum disulfide for NO2 detection at room temperature

In this work,the two-dimensional MoS2 film was prepared by sulfuring the molybdenum atomic layer on SiO2/Si substrate.The reaction temperature,heating rate,holding time and carrier gas flow rate were inve stigated compre hensively.The quality of MoS2 film was characterized by optical microscopy,atomic fo rce microscopy,Raman and photoluminescence spectro scopy.The characte rization results showed that the optimum synthesis parameters were heating rate of 25℃/min,reaction temperature of 750℃,holding time of 30 min and carrier gas velocity of 100 sccm.The MoS2 gas sensor was fabricated and its gas sensing performance was tested.The test results indicated that the sensor had a good response to both reducing gas(NH3)and oxidizing gas(NO2)at room temperature.The sensitivity to 100 ppm of NO2 was 31.3%,and the response/recovery times were 4 s and 5 s,respectively.In addition,the limit of detection could be as low as 1 ppm.This work helps us to develop low power and integrable room temperature NO2 sensors.

Tunable light emission from carbon dots by controlling surface defects

Carbon dots(CDs)are metal-free fluorescent materials that can be used in optical and electronic devices,but few studies have focused on one-step synthesis routes for CDs with tunable color and high photoluminescence quantum yield(PLQY).Herein,CDs with tunable light emission were synthesized using a novel amide-assisted solvothermal approach.The as-prepared CDs were well dispersed and homogeneous,with average diameters of approximately 2.0–4.0 nm,depending on the dopants.Owing to the surface states with different ratios of nitrogen-and oxygen-related species,different CDs can exhibit blue,green,red,or white emission with relatively high PLQYs of 61.6%,41.3%,29.1%and 19.7%,respectively.XPS measurements,in conjunction with DFT calculations,indicate that nitrogen substitution(pyridinic/pyrrolic nitrogen)dominates the blue emission,while introducing oxygen functional groups lowered the LUMO energy level,which resulted in redder emission.In addition,the CDs are demonstrated as a bioimaging probe in both in vitro and in vivo assays,and the white light CDs have been demonstrated to be potential fluorescent materials for white-light-emitting diode(WLED).

Preparation and formaldehyde sensitive properties of N-GQDs/SnO2 nanocomposite

Graphene quantum dots(GQDs)have both the properties of graphene and semiconductor quantum dots,and exhibit stronger quantum confinement effect and boundary effect than graphene.In addition,the band gap of GQDs will transform to non-zero from 0 eV of graphene by surface functionalization,which can be dispersed in common solvents and compounded with solid materials.In this work,the SnO2 nanosheets were prepared by hydrothermal method.As the sensitizer,nitrogen-doped graphene quantum dots(N-GQDs)were prepared and composited with SnO2 nanosheets.Sensing performance of pristine SnO2 and N-GQDs/SnO2 were investigated with HCHO as the target gas.The response(Ra/Rg)of0.1%N-GQDs/SnO2 was 256 for 100 ppm HCHO at 60℃,which was about 2.2 times higher than pristine SnO2 nanosheet.In addition,the material also had excellent selectivity and low operation temperature.The high sensitivity of N-GQDs/SnO2 was attributed to the increase of active sites on materials surface and the electrical regulation of N-GQDs.This research is helpful to develop new HCHO gas sensor and expand the application field of GQDs.

Highly sensitive acetone gas sensor based on ultra-low content bimetallic PtCu modified WO3·H2O hollow sphere

Acetone is an important industrial raw material as well as biomarker in medical diagnosis.The detection of acetone has great significance for safety and health.However,high selectivity and low concentration(ppb level)detection remain challenges for semiconductor gas sensor.Herein,we present a novel sensitive material with bimetallic PtCu nanocrystal modified on WO3·H2O hollow spheres(HS),which shows high sensitivity,excellent selectivity,fast response/recovery speed and low limit of detection(LOD)to acetone detection.Noteworthy,the response(Ra/Rg)of WO3·H2O HS sensor increased by 9.5 times after modification with 0.02%bimetallic PtCu nanocrystals.The response of PtCu/WO3·H2O HS to 50 ppm acetone is as high as 204.9 with short response/recovery times(3.4 s/7.5 s).Finally,the gassensitivity mechanism was discussed based on gas sensitivity test results.This research will offer a new route for high efficient acetone detection.

Solar-Powered Environmentally Friendly Hydrogen Production:Advanced Technologies for Sunlight-Electricity-Hydrogen Nexus

Hydrogen production from water splitting is a clean and sustainable hydrogen production route to alleviate the current energy crisis.However,factors such as energy conversion efficiency,cost-effectiveness,and social benefit limit their industrial application.Therefore,the development of advanced water splitting technologies using clean and renewable energy has become an important research goal of the world.Converting endless solar energy into hydrogen energy directly or indirectly is an effective way to reduce the energy input of hydrogen production.This review focuses on the latest advances in the coupling design of renewable energy supply devices and catalytic electrodes in hydrogen production systems.We not only review the single hydrogen production system based on photochemical,photoelectrochemical,photovoltaic,thermoelectric,pyroelectric,and piezoelectric devices,but also discuss the complex systems of the multiple devices.The structural design of energy supply devices and catalytic electrodes and the study of hydrogen production performance in different systems will be critically discussed in this work.Finally,current challenges and future perspectives of advanced technologies for sunlight-electricity-hydrogen nexus are also presented.It is hoped that this review will provide a timely reference for advancing the development of sunlight-electricity-hydrogen nexus and thus achieve the goal of sustainable production of green hydrogen.