Alzheimer’s disease is a prevalent and debilitating neurodegenerative condition that profoundly affects a patient’s daily functioning with progressive cognitive decline,which can be partly attributed to impaired hip...Alzheimer’s disease is a prevalent and debilitating neurodegenerative condition that profoundly affects a patient’s daily functioning with progressive cognitive decline,which can be partly attributed to impaired hippocampal neurogenesis.Neurogenesis in the hippocampal dentate gyrus is likely to persist throughout life but declines with aging,especially in Alzheimer’s disease.Recent evidence indicated that RNA-binding protein 8A(Rbm8a)promotes the proliferation of neural progenitor cells,with lower expression levels observed in Alzheimer’s disease patients compared with healthy people.This study investigated the hypothesis that Rbm8a overexpression may enhance neurogenesis by promoting the proliferation of neural progenitor cells to improve memory impairment in Alzheimer’s disease.Therefore,Rbm8a overexpression was induced in the dentate gyrus of 5×FAD mice to validate this hypothesis.Elevated Rbm8a levels in the dentate gyrus triggered neurogenesis and abated pathological phenotypes(such as plaque formation,gliosis reaction,and dystrophic neurites),leading to ameliorated memory performance in 5×FAD mice.RNA sequencing data further substantiated these findings,showing the enrichment of differentially expressed genes involved in biological processes including neurogenesis,cell proliferation,and amyloid protein formation.In conclusion,overexpressing Rbm8a in the dentate gyrus of 5×FAD mouse brains improved cognitive function by ameliorating amyloid-beta-associated pathological phenotypes and enhancing neurogenesis.展开更多
Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types,including osteoblast(OB)differentiation and function.Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive.A...Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types,including osteoblast(OB)differentiation and function.Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive.ATP6AP2,an accessory subunit of V-ATPase,plays important roles in multiple cell types/organs and multiple signaling pathways.However,little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation.Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions.Conditionally knocking out(CKO)ATP6AP2 in the OB-lineage cells(Atp6ap2^(Ocn-Cre))reduced trabecular,but not cortical,bone formation and bone mass.Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in ATP6AP2-KO BMSCs and OBs,but not osteocytes.Additional in vitro and in vivo studies revealed impairedβ-catenin signaling in ATP6AP2-KO BMSCs and OBs,but not osteocytes,under both basal and Wnt stimulated conditions,although LRP5 was decreased in ATP6AP2-KO osteocytes,but not BMSCs.Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression ofβ-catenin phosphorylation,but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane,thus preventing their degradation.Expression of activeβ-catenin diminished the OB differentiation deficit in ATP6AP2-KO BMSCs.Taken together,these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability,and thus regulatingβ-catenin levels,demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.展开更多
Patients with Alzheimer’s disease(AD)often have lower bone mass than healthy individuals.However,the mechanisms underlying this change remain elusive.Previously,we found that Tg2576 mice,an AD animal model that ubiqu...Patients with Alzheimer’s disease(AD)often have lower bone mass than healthy individuals.However,the mechanisms underlying this change remain elusive.Previously,we found that Tg2576 mice,an AD animal model that ubiquitously expresses Swedish mutant amyloid precursor protein(APPswe),shows osteoporotic changes,reduced bone formation,and increased bone resorption.To understand how bone deficits develop in Tg2576 mice,we used a multiplex antibody array to screen for serum proteins that are altered in Tg2576 mice and identified hepcidin,a master regulator of iron homeostasis.We further investigated hepcidin’s function in bone homeostasis and found that hepcidin levels were increased not only in the serum but also in the liver,muscle,and osteoblast(OB)lineage cells in Tg2576 mice at both the mRNA and protein levels.We then generated mice selectively expressing hepcidin in hepatocytes or OB lineage cells,which showed trabecular bone loss and increased osteoclast(OC)-mediated bone resorption.Further cell studies suggested that hepcidin increased OC precursor proliferation and differentiation by downregulating ferroportin(FPN)expression and increasing intracellular iron levels.In OB lineage cells,APPswe enhanced hepcidin expression by inducing ER stress and increasing OC formation,in part through hepcidin.Together,these results suggest that increased hepcidin expression in hepatocytes and OB lineage cells in Tg2576 mice contributes to enhanced osteoclastogenesis and trabecular bone loss,identifying the hepcidin-FPN-iron axis as a potential therapeutic target to prevent AD-associated bone loss.展开更多
Jets are commonly observed astrophysical phenomena.To study the x-ray emission characteristics of jets,a series of radial foil Z-pinch experiments are carried out on the Primary Test Stand at the Institute of Fluid Ph...Jets are commonly observed astrophysical phenomena.To study the x-ray emission characteristics of jets,a series of radial foil Z-pinch experiments are carried out on the Primary Test Stand at the Institute of Fluid Physics,China Academy of Engineering Physics.In these experiments,x-ray emission ranging from the soft region(0.1–10 keV)to the hard region(10 keV–500 keV)is observed when the magnetic cavity breaks.The radiation flux of soft x-rays is measured by an x-ray diode and the dose rate of the hard x-rays by an Si-PIN detector.The experimental results indicate that the energy of the soft x-rays is several tens of kilojoules and that of the hard x-rays is∼200 J.The radiation mechanismof the x-ray emission is briefly analyzed.This analysis indicates that the x-ray energy and the plasma kinetic energy come from the magnetic energy when the magnetic cavity breaks.The soft x-rays are thought to be produced by bremsstrahlung of thermal electrons(∼100 eV),and the hard x-rays by bremsstrahlung of super-hot electrons(∼mega-electron-volt).These results may be helpful to explain the xray emission by the jets from young stellar objects.展开更多
We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No str...We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No structural phase transition is observed at atmospheric pressure based on the x-ray diffraction and Raman experiment.The high-pressure Raman experiment demonstrates that two structural phase transitions exist at 0.94 GPa and 6.53 GPa,respectively.The mechanism of negative thermal expansion inβ-CuZnV_(2)O_(7)is interpreted by the variations of the angles between atoms intuitively and the phonon anharmonicity intrinsically resorting to the negative Grüneisen parameter.展开更多
Germanium diselenide(GeSe_(2))is a promising candidate for electronic devices because of its unique crystal structure and optoelectronic properties.However,the evolution of lattice and electronic structure ofβ-GeSe_(...Germanium diselenide(GeSe_(2))is a promising candidate for electronic devices because of its unique crystal structure and optoelectronic properties.However,the evolution of lattice and electronic structure ofβ-GeSe_(2)at high pressure is still uncertain.Here we prepared high-qualityβ-GeSe_(2)single crystals by chemical vapor transfer(CVT)technique and performed systematic experimental studies on the evolution of lattice structure and bandgap ofβ-GeSe_(2)under pressure.High-precision high-pressure ultra low frequency(ULF)Raman scattering and synchrotron angle-dispersive x-ray diffraction(ADXRD)measurements support that no structural phase transition exists under high pressure up to 13.80 GPa,but the structure ofβ-GeSe_(2)turns into a disordered state near 6.91 GPa and gradually becomes amorphous forming an irreversibly amorphous crystal at 13.80 GPa.Two Raman modes keep softening abnormally upon pressure.The bandgap ofβ-GeSe_(2)reduced linearly from 2.59 eV to 1.65 eV under pressure with a detectable narrowing of 36.5%,and the sample under pressure performs the piezochromism phenomenon.The bandgap after decompression is smaller than that in the atmospheric pressure environment,which is caused by incomplete recrystallization.These results enrich the insight into the structural and optical properties ofβ-GeSe_(2)and demonstrate the potential of pressure in modulating the material properties of two-dimensional(2D)Ge-based binary material.展开更多
Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero ...Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero thermal expansion materials.Here,according to this concept,a tetragonal tungstate Cs_(2)W_(3)O_(10)with zero expansion has been found.There is no structure phase transition as increasing temperature from 150 K to 573 K.The coefficient of thermal expansion of axes and volume areαa=0.0074×10^(-6)K^(-1),αc=1.63×10^(-6)K^(-1),andαV=1.60×10^(-6)K^(-1),respectively,in the temperature range of 150~573 K.The temperature-and pressure-dependent Raman spectra reveal that the vibrations of WO6octahedra libration modes with positive total anharmonicity and W-O-W bending mode with negative Grüneisen parameter are possibly the origin of zero thermal expansion in Cs_(2)W_(3)O_(10).展开更多
Background Hydrogen sulphide(H_(2)S)is considered as the third member of the gasotransmitter family,along with nitric oxide(NO)and carbon monoxide.H_(2)S has been reported to induce angiogenesis by promoting the growt...Background Hydrogen sulphide(H_(2)S)is considered as the third member of the gasotransmitter family,along with nitric oxide(NO)and carbon monoxide.H_(2)S has been reported to induce angiogenesis by promoting the growth,migration and tube-like structure formation of endothelial cells.Those studies were conducted in conditions of cell culture,mouse Matrigel plug assay model,rat wound healing model or rat hindlimb ischaemia model.Recent in vivo studies showed the physiological importance of H_(2)S in muscle angiogenesis.However,the importance of endogenous H_(2)S for brain angiogenesis during development remains unknown.We therefore aimed at determining the role of H_(2)S in brain vascular development.Methods and results Both knockdown and knockout of H2S-producing enzymes,cystathionineβ-synthase(cbs)and cystathionineγ-lyase(cth),using morpholino oligonucleotides and clustered regularly interspaced short palindromic repeats/Cas9-mediated mutation,impaired brain vascular development of larval zebrafish.Incubation with the slow-releasing H_(2)S donor GYY4137 alleviated the defects of brain vascular development in cbs and cth morphants.Quantitative analysis of the midbrain vascular network showed that H_(2)S enhances angiogenesis without affecting the topological structure of the brain vasculature.Mechanically,nitric oxide synthase 2a(nos2a)expression and NO production were decreased in both cbs and cth morphants.Overexpression of nos2a by coinjection of cbs or cth MO with full-length zebrafish nos2a mRNA alleviated the brain vascular developmental defects in cbs and cth morphants.Conclusion We conclude that H_(2)S promotes brain developmental angiogenesis via the NOS/NO pathway in zebrafish.展开更多
This paper first highlights recent developments in lean direct injection(LDI)combustion technology.In view of the needs and opportunities to lower emissions and expand the operability range of LDI,fundamental research...This paper first highlights recent developments in lean direct injection(LDI)combustion technology.In view of the needs and opportunities to lower emissions and expand the operability range of LDI,fundamental research has been undertaken to elucidate the effects of air swirler vane angle,air swirler rotation direction,and overall equivalence ratio on the LDI flow field and flame structure/response.Moreover,additional investigation has been conducted to understand the fundamental differences between representative LDI and airblast injectors in order to highlight the importance of the flare feature to LDI venturi geometry.The results of these fundamental studies are discussed to help identify possible areas for optimization to generic LDI designs that may improve individual swirler performance.展开更多
We report a photoelectrochemical(PEC)sensor for selective detection of ascorbic(AA)by introducing Z-scheme Bi_(2)S_(3)@nitrogen doped graphene quantum dots(Bi_(2)S_(3)@NGQDs)heterojunctions as efficient photoactive sp...We report a photoelectrochemical(PEC)sensor for selective detection of ascorbic(AA)by introducing Z-scheme Bi_(2)S_(3)@nitrogen doped graphene quantum dots(Bi_(2)S_(3)@NGQDs)heterojunctions as efficient photoactive species.The Bi_(2)S_(3)@NGQDs were successfully prepared by a simple hydrothermal process,and the microstructures and components were investigated by various characterized techniques.The photocurrent of the Bi_(2)S_(3)@NGQDs-based sensor increased significantly in the presence of AA and showed excellent selectivity and stability for AA detection in the presence of some other antioxidants and small molecules.A wide linear range of 0.1–5µmol/L and 5–1380µmol/L was achieved for the AA detection with a detection limit of 36 nmol/L(S/N=3).Moreover,the proposed PEC sensor achieved the determination of AA in real red peppers and commercially available vitamin C tablets samples.展开更多
基金supported by the National Natural Science Foundation of China,No.91849104(to YW)。
文摘Alzheimer’s disease is a prevalent and debilitating neurodegenerative condition that profoundly affects a patient’s daily functioning with progressive cognitive decline,which can be partly attributed to impaired hippocampal neurogenesis.Neurogenesis in the hippocampal dentate gyrus is likely to persist throughout life but declines with aging,especially in Alzheimer’s disease.Recent evidence indicated that RNA-binding protein 8A(Rbm8a)promotes the proliferation of neural progenitor cells,with lower expression levels observed in Alzheimer’s disease patients compared with healthy people.This study investigated the hypothesis that Rbm8a overexpression may enhance neurogenesis by promoting the proliferation of neural progenitor cells to improve memory impairment in Alzheimer’s disease.Therefore,Rbm8a overexpression was induced in the dentate gyrus of 5×FAD mice to validate this hypothesis.Elevated Rbm8a levels in the dentate gyrus triggered neurogenesis and abated pathological phenotypes(such as plaque formation,gliosis reaction,and dystrophic neurites),leading to ameliorated memory performance in 5×FAD mice.RNA sequencing data further substantiated these findings,showing the enrichment of differentially expressed genes involved in biological processes including neurogenesis,cell proliferation,and amyloid protein formation.In conclusion,overexpressing Rbm8a in the dentate gyrus of 5×FAD mouse brains improved cognitive function by ameliorating amyloid-beta-associated pathological phenotypes and enhancing neurogenesis.
基金supported in part by grants from the National Institutes of Health(AG045781,AG051510,and AG066526)(to WCX).
文摘Wnt/β-catenin signaling is critical for various cellular processes in multiple cell types,including osteoblast(OB)differentiation and function.Exactly how Wnt/β-catenin signaling is regulated in OBs remain elusive.ATP6AP2,an accessory subunit of V-ATPase,plays important roles in multiple cell types/organs and multiple signaling pathways.However,little is known whether and how ATP6AP2 in OBs regulates Wnt/β-catenin signaling and bone formation.Here we provide evidence for ATP6AP2 in the OB-lineage cells to promote OB-mediated bone formation and bone homeostasis selectively in the trabecular bone regions.Conditionally knocking out(CKO)ATP6AP2 in the OB-lineage cells(Atp6ap2^(Ocn-Cre))reduced trabecular,but not cortical,bone formation and bone mass.Proteomic and cellular biochemical studies revealed that LRP6 and N-cadherin were reduced in ATP6AP2-KO BMSCs and OBs,but not osteocytes.Additional in vitro and in vivo studies revealed impairedβ-catenin signaling in ATP6AP2-KO BMSCs and OBs,but not osteocytes,under both basal and Wnt stimulated conditions,although LRP5 was decreased in ATP6AP2-KO osteocytes,but not BMSCs.Further cell biological studies uncovered that osteoblastic ATP6AP2 is not required for Wnt3a suppression ofβ-catenin phosphorylation,but necessary for LRP6/β-catenin and N-cadherin/β-catenin protein complex distribution at the cell membrane,thus preventing their degradation.Expression of activeβ-catenin diminished the OB differentiation deficit in ATP6AP2-KO BMSCs.Taken together,these results support the view for ATP6AP2 as a critical regulator of both LRP6 and N-cadherin protein trafficking and stability,and thus regulatingβ-catenin levels,demonstrating an un-recognized function of osteoblastic ATP6AP2 in promoting Wnt/LRP6/β-catenin signaling and trabecular bone formation.
基金supported in part by grants from the National Institutes of Health(AG051773)the U.S.Department of Veterans Affairs(BX000838)by the Meisel family and InMotion in Cleveland,Ohio.
文摘Patients with Alzheimer’s disease(AD)often have lower bone mass than healthy individuals.However,the mechanisms underlying this change remain elusive.Previously,we found that Tg2576 mice,an AD animal model that ubiquitously expresses Swedish mutant amyloid precursor protein(APPswe),shows osteoporotic changes,reduced bone formation,and increased bone resorption.To understand how bone deficits develop in Tg2576 mice,we used a multiplex antibody array to screen for serum proteins that are altered in Tg2576 mice and identified hepcidin,a master regulator of iron homeostasis.We further investigated hepcidin’s function in bone homeostasis and found that hepcidin levels were increased not only in the serum but also in the liver,muscle,and osteoblast(OB)lineage cells in Tg2576 mice at both the mRNA and protein levels.We then generated mice selectively expressing hepcidin in hepatocytes or OB lineage cells,which showed trabecular bone loss and increased osteoclast(OC)-mediated bone resorption.Further cell studies suggested that hepcidin increased OC precursor proliferation and differentiation by downregulating ferroportin(FPN)expression and increasing intracellular iron levels.In OB lineage cells,APPswe enhanced hepcidin expression by inducing ER stress and increasing OC formation,in part through hepcidin.Together,these results suggest that increased hepcidin expression in hepatocytes and OB lineage cells in Tg2576 mice contributes to enhanced osteoclastogenesis and trabecular bone loss,identifying the hepcidin-FPN-iron axis as a potential therapeutic target to prevent AD-associated bone loss.
基金The authors wish to thank the PTS crew and all those contributing to this work.This work was supported in part by Science Challenge Program Grant No.JCKY2016212A505 and by NSFC Grant Nos.11605188 and 11705186.
文摘Jets are commonly observed astrophysical phenomena.To study the x-ray emission characteristics of jets,a series of radial foil Z-pinch experiments are carried out on the Primary Test Stand at the Institute of Fluid Physics,China Academy of Engineering Physics.In these experiments,x-ray emission ranging from the soft region(0.1–10 keV)to the hard region(10 keV–500 keV)is observed when the magnetic cavity breaks.The radiation flux of soft x-rays is measured by an x-ray diode and the dose rate of the hard x-rays by an Si-PIN detector.The experimental results indicate that the energy of the soft x-rays is several tens of kilojoules and that of the hard x-rays is∼200 J.The radiation mechanismof the x-ray emission is briefly analyzed.This analysis indicates that the x-ray energy and the plasma kinetic energy come from the magnetic energy when the magnetic cavity breaks.The soft x-rays are thought to be produced by bremsstrahlung of thermal electrons(∼100 eV),and the hard x-rays by bremsstrahlung of super-hot electrons(∼mega-electron-volt).These results may be helpful to explain the xray emission by the jets from young stellar objects.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874328,12004339,11574276,and 21905252)the China Postdoctoral Science Foundation(Grant Nos.2018M640679,2019T120629,and 2019M652558)the Zhongyuan Academician Foundation(Grant No.ZYQR201810163)。
文摘We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No structural phase transition is observed at atmospheric pressure based on the x-ray diffraction and Raman experiment.The high-pressure Raman experiment demonstrates that two structural phase transitions exist at 0.94 GPa and 6.53 GPa,respectively.The mechanism of negative thermal expansion inβ-CuZnV_(2)O_(7)is interpreted by the variations of the angles between atoms intuitively and the phonon anharmonicity intrinsically resorting to the negative Grüneisen parameter.
基金the National Natural Science Foundation of China(Grant Nos.12004339,11874328,11904322,61804047,22071221,and 21905252)China Postdoctoral Science Foundation(Grant Nos.2018M640679 and 2019T120629)the Zhongyuan Academician Foundation(Grant No.ZYQR201810163)。
文摘Germanium diselenide(GeSe_(2))is a promising candidate for electronic devices because of its unique crystal structure and optoelectronic properties.However,the evolution of lattice and electronic structure ofβ-GeSe_(2)at high pressure is still uncertain.Here we prepared high-qualityβ-GeSe_(2)single crystals by chemical vapor transfer(CVT)technique and performed systematic experimental studies on the evolution of lattice structure and bandgap ofβ-GeSe_(2)under pressure.High-precision high-pressure ultra low frequency(ULF)Raman scattering and synchrotron angle-dispersive x-ray diffraction(ADXRD)measurements support that no structural phase transition exists under high pressure up to 13.80 GPa,but the structure ofβ-GeSe_(2)turns into a disordered state near 6.91 GPa and gradually becomes amorphous forming an irreversibly amorphous crystal at 13.80 GPa.Two Raman modes keep softening abnormally upon pressure.The bandgap ofβ-GeSe_(2)reduced linearly from 2.59 eV to 1.65 eV under pressure with a detectable narrowing of 36.5%,and the sample under pressure performs the piezochromism phenomenon.The bandgap after decompression is smaller than that in the atmospheric pressure environment,which is caused by incomplete recrystallization.These results enrich the insight into the structural and optical properties ofβ-GeSe_(2)and demonstrate the potential of pressure in modulating the material properties of two-dimensional(2D)Ge-based binary material.
基金supported by the National Natural Science Foundation of China(Nos.22071221,21905252)Natural Science Foundation of Henan Province(Nos.212300410086,222301420040 and 222300420325)。
文摘Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero thermal expansion materials.Here,according to this concept,a tetragonal tungstate Cs_(2)W_(3)O_(10)with zero expansion has been found.There is no structure phase transition as increasing temperature from 150 K to 573 K.The coefficient of thermal expansion of axes and volume areαa=0.0074×10^(-6)K^(-1),αc=1.63×10^(-6)K^(-1),andαV=1.60×10^(-6)K^(-1),respectively,in the temperature range of 150~573 K.The temperature-and pressure-dependent Raman spectra reveal that the vibrations of WO6octahedra libration modes with positive total anharmonicity and W-O-W bending mode with negative Grüneisen parameter are possibly the origin of zero thermal expansion in Cs_(2)W_(3)O_(10).
基金supported by a grant from the Natural Science Foundation of China(31770800,91849104,81870274,81571329).
文摘Background Hydrogen sulphide(H_(2)S)is considered as the third member of the gasotransmitter family,along with nitric oxide(NO)and carbon monoxide.H_(2)S has been reported to induce angiogenesis by promoting the growth,migration and tube-like structure formation of endothelial cells.Those studies were conducted in conditions of cell culture,mouse Matrigel plug assay model,rat wound healing model or rat hindlimb ischaemia model.Recent in vivo studies showed the physiological importance of H_(2)S in muscle angiogenesis.However,the importance of endogenous H_(2)S for brain angiogenesis during development remains unknown.We therefore aimed at determining the role of H_(2)S in brain vascular development.Methods and results Both knockdown and knockout of H2S-producing enzymes,cystathionineβ-synthase(cbs)and cystathionineγ-lyase(cth),using morpholino oligonucleotides and clustered regularly interspaced short palindromic repeats/Cas9-mediated mutation,impaired brain vascular development of larval zebrafish.Incubation with the slow-releasing H_(2)S donor GYY4137 alleviated the defects of brain vascular development in cbs and cth morphants.Quantitative analysis of the midbrain vascular network showed that H_(2)S enhances angiogenesis without affecting the topological structure of the brain vasculature.Mechanically,nitric oxide synthase 2a(nos2a)expression and NO production were decreased in both cbs and cth morphants.Overexpression of nos2a by coinjection of cbs or cth MO with full-length zebrafish nos2a mRNA alleviated the brain vascular developmental defects in cbs and cth morphants.Conclusion We conclude that H_(2)S promotes brain developmental angiogenesis via the NOS/NO pathway in zebrafish.
文摘This paper first highlights recent developments in lean direct injection(LDI)combustion technology.In view of the needs and opportunities to lower emissions and expand the operability range of LDI,fundamental research has been undertaken to elucidate the effects of air swirler vane angle,air swirler rotation direction,and overall equivalence ratio on the LDI flow field and flame structure/response.Moreover,additional investigation has been conducted to understand the fundamental differences between representative LDI and airblast injectors in order to highlight the importance of the flare feature to LDI venturi geometry.The results of these fundamental studies are discussed to help identify possible areas for optimization to generic LDI designs that may improve individual swirler performance.
基金supported by the National Natural Science Foundation of China (Nos.22172040,21974031)the Project of the Department of Science and Techniques of Guangdong Province,China (Nos.2021A1515010180,2019B010933001)+1 种基金the Guangzhou Municipal Science and Technology Bureau,China (No.202102010449)the Project of the Department of Guangdong Provincial Public Security,China (No.GZQC20-PZ11-FD084).
文摘We report a photoelectrochemical(PEC)sensor for selective detection of ascorbic(AA)by introducing Z-scheme Bi_(2)S_(3)@nitrogen doped graphene quantum dots(Bi_(2)S_(3)@NGQDs)heterojunctions as efficient photoactive species.The Bi_(2)S_(3)@NGQDs were successfully prepared by a simple hydrothermal process,and the microstructures and components were investigated by various characterized techniques.The photocurrent of the Bi_(2)S_(3)@NGQDs-based sensor increased significantly in the presence of AA and showed excellent selectivity and stability for AA detection in the presence of some other antioxidants and small molecules.A wide linear range of 0.1–5µmol/L and 5–1380µmol/L was achieved for the AA detection with a detection limit of 36 nmol/L(S/N=3).Moreover,the proposed PEC sensor achieved the determination of AA in real red peppers and commercially available vitamin C tablets samples.
