Innovative catalysts based on a "porous glass" support material were developed and investigated for the reduction of benzalace-tophenone. The easy preparation conditions and possibility to use different meta...Innovative catalysts based on a "porous glass" support material were developed and investigated for the reduction of benzalace-tophenone. The easy preparation conditions and possibility to use different metals (e.g. Pd, Pt, Rh) for impregnation gave a broad variety of these catalysts. Hydrogenation experiments with these supported catalysts were carried out under different hydrogen pressures and temperatures. Porous glass catalysts with Pd as the active component gave chemoselective hydrogenation of benzalacetophenone, while Pt- and Rh-catalysts tended to further reduce the carbonyl group, especially at elevated hydrogen pressures and temperatures. Kinetic analysis of the reactions revealed these had zero order kinetics, which was independent of the type of porous glass support and solvent used.展开更多
Background:Cells of the retinal pigment epithelium(RPE)accumulate different kinds of granules(lipofuscin,melanolipofuscin,melanosomes)within their cell bodies,with lipofuscin and melanolipofuscin being autofluorescent...Background:Cells of the retinal pigment epithelium(RPE)accumulate different kinds of granules(lipofuscin,melanolipofuscin,melanosomes)within their cell bodies,with lipofuscin and melanolipofuscin being autofluorescent after blue light excitation.High amounts of lipofuscin granules within the RPE have been associated with the development of RPE cell death and age-related macular degeneration(AMD);however,this has not been confirmed in histology so far.Here,based on our previous dataset of RPE granule characteristics,we report the characteristics of RPE cells from human donor eyes that show either high or low numbers of intracellular granules or high or low autofluorescence(AF)intensities.Methods:RPE flatmounts of fifteen human donors were examined using high-resolution structured illumination microscopy(HR-SIM)and laser scanning microscopy(LSM).Autofluorescent granules were analyzed regarding AF phenotype and absolute number of granules.In addition,total AF intensity per cell and granule density(number of granules per cell area)were determined.For the final analysis,RPE cells with total granule number below 5th or above the 95th percentile,or a total AF intensity±1.5 standard deviations above or below the mean were included,and compared to the average RPE cell at the same location.Data are presented as mean±standard deviation.Results:Within 420 RPE cells examined,42 cells were further analyzed due to extremes regarding total granule numbers.In addition,20 RPE cells had AF 1.5 standard deviations below,28 RPE cells above the mean local AF intensity.Melanolipofuscin granules predominate in RPE cells with low granule content and low AF intensity.RPE cells with high granule content have nearly twice(1.8 times)as many granules as an average RPE cell.Conclusions:In normal eyes,outliers regarding autofluorescent granule load and AF intensity signals are rare among RPE cells,suggesting that granule deposition and subsequent AF follows intrinsic control mechanisms at a cellular level.The AF of a cell is related to the composition of intracellular granule types.Ongoing studies using AMD donor eyes will examine possible disease related changes in granule distribution and further put lipofuscin´s role in aging and AMD further into perspective.展开更多
Platinum-palladium nanoparticles are synthesized and characterized with regard to their application in fuel cells due to their high (electro) catalytic activity. Different preparation times are applied leading to diff...Platinum-palladium nanoparticles are synthesized and characterized with regard to their application in fuel cells due to their high (electro) catalytic activity. Different preparation times are applied leading to different structures, from Pd cubic to core-shell PtPd concave, and different chemical compositions. The resulting particles are studied via Transmission Electron Microscopy (TEM) and in-situ X-ray absorption fine structure (XAFS) measurements. The latter allows the investigation of the oxygen reduction reaction following the variations with varying applied potentials by analysis using the Iterative Transformation Factor Analysis (ITFA) and the creation of a two-component system that consists of metallic Pt-Pd and the related oxide. With the used model, the different concentrations of the oxide are linked to the consecutive chemical steps of the oxygen reduction reaction. Finally, the catalytic activity of the particles is determined via linear scanning voltammetry and reveals a dependence on the shape and the composition of the particles.展开更多
Objective: To validate an intracoronary Doppler ultrasound device for high intensity transient signals(HITS) detection and to assess the incidence of HITS during percutaneous coronary intervention(PCI). Methods and Re...Objective: To validate an intracoronary Doppler ultrasound device for high intensity transient signals(HITS) detection and to assess the incidence of HITS during percutaneous coronary intervention(PCI). Methods and Results: In an in vitro model, particle count and number of HITS detected by an intracoronary 0.014 inch Doppler wire were closely correlated(r=0.97, p< 0.001). In the clinical study, 32 patients(mean(SD) age 61(11) years; 23 men, nine women) with coronary artery disease were treated with balloon dilatation and stent implantation for a single vessel stenosis. In these patients HITS were detected during PCI in 84%(27 of 32). Reproducibility(r=0.99, p< 0.001) and interobserver agreement(r=0.84, p< 0.001)of HITS counts were significant. The number of HITS after stent implantation was significantly higher than after balloon dilatation(11(7) v 2(4), p< 0.001). Postprocedural coronary flow velocity reserve(CFVR) was< 2.0 in 55%(16 of 29) of all patients after balloon dilatation and< 2.0 in 23%(six of 26) after stent implantation. The number of HITS after stent implantation did not differ significantly between patients with CFVR< 2.0 and patients with CFVR ≥2.0(12(8) v 10(7), not significant). Conclusions: Embolic particles can be detected as HITS by an intracoronary Doppler ultrasound device. Coronary microembolism is often observed during PCI, especially after stent implantation. However, the incidence of HITS alone does not explain a reduced CFVR after PCI.展开更多
Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhan...Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhanced Raman scattering(SERS)has been widely used in scientific investigations and material analysis.The large enhanced Raman signals are mainly caused by the extremely enhanced electromagnetic field that results from localized surface plasmon polaritons.Recently,a novel SERS technology called remote SERS has been reported,combining both localized surface plasmon polaritons and propagating surface plasmon polaritons(PSPPs,or called plasmonic waveguide),which may be found in prominent applications in special circumstances compared to traditional local SERS.In this article,we review the mechanism of remote SERS and its development since it was first reported in 2009.Various remote metal systems based on plasmonic waveguides,such as nanoparticle–nanowire systems,single nanowire systems,crossed nanowire systems and nanowire dimer systems,are introduced,and recent novel applications,such as sensors,plasmon-driven surface-catalyzed reactions and Raman optical activity,are also presented.Furthermore,studies of remote SERS in dielectric and organic systems based on dielectric waveguides remind us that this useful technology has additional,tremendous application prospects that have not been realized in metal systems.展开更多
The steady progress in medical diagnosis and treatment of diseases largely hinges on the steady development and improvement of modern imaging modalities.Raman spectroscopy has attracted increasing attention for clinic...The steady progress in medical diagnosis and treatment of diseases largely hinges on the steady development and improvement of modern imaging modalities.Raman spectroscopy has attracted increasing attention for clinical applications as it is label-free,non-invasive,and delivers molecular fingerprinting information of a sample.In combination with fiber optic probes,it also allows easy access to different body parts of a patient.However,image acquisition with fiber optic probes is currently not possible.Here,we introduce a fiber optic probe-based Raman imaging system for the real-time molecular virtual reality data visualization of chemical boundaries on a computer screen and the physical world.The approach is developed around a computer vision-based positional tracking system in conjunction with photometric stereo and augmented and mixed chemical reality,enabling molecular imaging and direct visualization of molecular boundaries of three-dimensional surfaces.The proposed approach achieves a spatial resolution of 0.5 mm in the transverse plane and a topology resolution of 0.6 mm,with a spectral sampling frequency of 10 Hz,and can be used to image large tissue areas in a few minutes,making it highly suitable for clinical tissueboundary demarcation.A variety of applications on biological samples,i.e.,distribution of pharmaceutical compounds,brain-tumor phantom,and various types of sarcoma have been characterized,showing that the system enables rapid and intuitive assessment of molecular boundaries.展开更多
Redox Responsive Transcription Factor1 (RRTF1) in Arabidopsis is rapidly and transiently upregulated by H202, as well as biotic- and abiotic-induced redox signals. RRTF1 is highly conserved in angio- sperms, but its...Redox Responsive Transcription Factor1 (RRTF1) in Arabidopsis is rapidly and transiently upregulated by H202, as well as biotic- and abiotic-induced redox signals. RRTF1 is highly conserved in angio- sperms, but its physiological role remains elusive. Here we show that inactivation of RRTF1 restricts and overexpression promotes reactive oxygen species (ROS) accumulation in response to stress. Transgenic lines overexpressing RRTF1 are impaired in root and shoot development, light sensitive, and susceptible to Alternaria brassicae infection. These symptoms are diminished by the beneficial root endophyte Piriformospora indica, which reduces ROS accumulation locally in roots and systemi- cally in shoots, and by antioxidants and ROS inhibitors that scavenge ROS. More than 800 genes were detected in mature leaves and seedlings of transgenic lines overexpressing RRTF1; ∽40% of them have stress-, redox-, ROS-regulated-, ROS-scavenging-, defense-, cell death- and related functions. Bioinformatic analyses and in vitro DNA binding assays demonstrate that RRTF1 binds to GCC-box-like sequences in the promoter of RRTFl-responsive genes. Upregulation of RRTF1 by stress stimuli and H202 requires WRKY18/40/60. RRTF1 is co-regulated with the phylogenet- ically related RAP2.6, which contains a GCC-box-like sequence in its promoter, but transgenic lines overexpressing RAP2.6 do not accumulate higher ROS levels. RRTF1 also stimulates systemic ROS accumulation in distal non-stressed leaves. We conclude that the elevated levels of the highly conserved RRTF1 induce ROS accumulation in response to ROS and ROS-producing abiotic and biotic stress signals.展开更多
Maintenance of tissue-specific stem cells is vital for organ homeostasis and organismal longevity.Hematopoietic stem cells(HSCs) are the most primitive cell type in the hematopoietic system.They divide asymmetricall...Maintenance of tissue-specific stem cells is vital for organ homeostasis and organismal longevity.Hematopoietic stem cells(HSCs) are the most primitive cell type in the hematopoietic system.They divide asymmetrically and give rise to daughter cells with HSC identity(selfrenewal) and progenitor progenies(differentiation),which further proliferate and differentiate into full hematopoietic lineages.Mammalian ageing process is accompanied with abnormalities in the HSC self-renewal and differentiation.Transcriptional changes and epigenetic modulations have been implicated as the key regulators in HSC ageing process.The DNA damage response(DDR)in the cells involves an orchestrated signaling pathway,consisting of cell cycle regulation,cell death and senescence,transcriptional regulation,as well as chromatin remodeling.Recent studies employing DNA repair-deficient mouse models indicate that DDR could intrinsically and extrinsically regulate HSC maintenance and play important roles in tissue homeostasis of the hematopoietic system.In this review,we summarize the current understanding of how the DDR determines the HSC fates and finally contributes to organismal ageing.展开更多
Nature Photonics 15,813-816(2021)https://doi.org/10.1038/s41566-021-00865-0 Control of light polarization over a wide range of optical wavelengths is highly desirable within a variety of applications.Fabrication of wa...Nature Photonics 15,813-816(2021)https://doi.org/10.1038/s41566-021-00865-0 Control of light polarization over a wide range of optical wavelengths is highly desirable within a variety of applications.Fabrication of waveplates,allowing for achromatic retardation usually requires a sophisticated combination of multiple layers of birefringent materials.展开更多
文摘Innovative catalysts based on a "porous glass" support material were developed and investigated for the reduction of benzalace-tophenone. The easy preparation conditions and possibility to use different metals (e.g. Pd, Pt, Rh) for impregnation gave a broad variety of these catalysts. Hydrogenation experiments with these supported catalysts were carried out under different hydrogen pressures and temperatures. Porous glass catalysts with Pd as the active component gave chemoselective hydrogenation of benzalacetophenone, while Pt- and Rh-catalysts tended to further reduce the carbonyl group, especially at elevated hydrogen pressures and temperatures. Kinetic analysis of the reactions revealed these had zero order kinetics, which was independent of the type of porous glass support and solvent used.
文摘Background:Cells of the retinal pigment epithelium(RPE)accumulate different kinds of granules(lipofuscin,melanolipofuscin,melanosomes)within their cell bodies,with lipofuscin and melanolipofuscin being autofluorescent after blue light excitation.High amounts of lipofuscin granules within the RPE have been associated with the development of RPE cell death and age-related macular degeneration(AMD);however,this has not been confirmed in histology so far.Here,based on our previous dataset of RPE granule characteristics,we report the characteristics of RPE cells from human donor eyes that show either high or low numbers of intracellular granules or high or low autofluorescence(AF)intensities.Methods:RPE flatmounts of fifteen human donors were examined using high-resolution structured illumination microscopy(HR-SIM)and laser scanning microscopy(LSM).Autofluorescent granules were analyzed regarding AF phenotype and absolute number of granules.In addition,total AF intensity per cell and granule density(number of granules per cell area)were determined.For the final analysis,RPE cells with total granule number below 5th or above the 95th percentile,or a total AF intensity±1.5 standard deviations above or below the mean were included,and compared to the average RPE cell at the same location.Data are presented as mean±standard deviation.Results:Within 420 RPE cells examined,42 cells were further analyzed due to extremes regarding total granule numbers.In addition,20 RPE cells had AF 1.5 standard deviations below,28 RPE cells above the mean local AF intensity.Melanolipofuscin granules predominate in RPE cells with low granule content and low AF intensity.RPE cells with high granule content have nearly twice(1.8 times)as many granules as an average RPE cell.Conclusions:In normal eyes,outliers regarding autofluorescent granule load and AF intensity signals are rare among RPE cells,suggesting that granule deposition and subsequent AF follows intrinsic control mechanisms at a cellular level.The AF of a cell is related to the composition of intracellular granule types.Ongoing studies using AMD donor eyes will examine possible disease related changes in granule distribution and further put lipofuscin´s role in aging and AMD further into perspective.
文摘Platinum-palladium nanoparticles are synthesized and characterized with regard to their application in fuel cells due to their high (electro) catalytic activity. Different preparation times are applied leading to different structures, from Pd cubic to core-shell PtPd concave, and different chemical compositions. The resulting particles are studied via Transmission Electron Microscopy (TEM) and in-situ X-ray absorption fine structure (XAFS) measurements. The latter allows the investigation of the oxygen reduction reaction following the variations with varying applied potentials by analysis using the Iterative Transformation Factor Analysis (ITFA) and the creation of a two-component system that consists of metallic Pt-Pd and the related oxide. With the used model, the different concentrations of the oxide are linked to the consecutive chemical steps of the oxygen reduction reaction. Finally, the catalytic activity of the particles is determined via linear scanning voltammetry and reveals a dependence on the shape and the composition of the particles.
文摘Objective: To validate an intracoronary Doppler ultrasound device for high intensity transient signals(HITS) detection and to assess the incidence of HITS during percutaneous coronary intervention(PCI). Methods and Results: In an in vitro model, particle count and number of HITS detected by an intracoronary 0.014 inch Doppler wire were closely correlated(r=0.97, p< 0.001). In the clinical study, 32 patients(mean(SD) age 61(11) years; 23 men, nine women) with coronary artery disease were treated with balloon dilatation and stent implantation for a single vessel stenosis. In these patients HITS were detected during PCI in 84%(27 of 32). Reproducibility(r=0.99, p< 0.001) and interobserver agreement(r=0.84, p< 0.001)of HITS counts were significant. The number of HITS after stent implantation was significantly higher than after balloon dilatation(11(7) v 2(4), p< 0.001). Postprocedural coronary flow velocity reserve(CFVR) was< 2.0 in 55%(16 of 29) of all patients after balloon dilatation and< 2.0 in 23%(six of 26) after stent implantation. The number of HITS after stent implantation did not differ significantly between patients with CFVR< 2.0 and patients with CFVR ≥2.0(12(8) v 10(7), not significant). Conclusions: Embolic particles can be detected as HITS by an intracoronary Doppler ultrasound device. Coronary microembolism is often observed during PCI, especially after stent implantation. However, the incidence of HITS alone does not explain a reduced CFVR after PCI.
基金This study was financially supported by the National Natural Science Foundation of China(Grants 11374353,11204390 and 11274149)the Fundamental Research Funds for the Central Universities(CQDXWL-2013-009)+1 种基金the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology(F12-254-1-00)Special Fund for Agro-scientific Research in the Public Interest(NO.201303045).
文摘Due to its amazing ability to manipulate light at the nanoscale,plasmonics has become one of the most interesting topics in the field of light–matter interaction.As a promising application of plasmonics,surface-enhanced Raman scattering(SERS)has been widely used in scientific investigations and material analysis.The large enhanced Raman signals are mainly caused by the extremely enhanced electromagnetic field that results from localized surface plasmon polaritons.Recently,a novel SERS technology called remote SERS has been reported,combining both localized surface plasmon polaritons and propagating surface plasmon polaritons(PSPPs,or called plasmonic waveguide),which may be found in prominent applications in special circumstances compared to traditional local SERS.In this article,we review the mechanism of remote SERS and its development since it was first reported in 2009.Various remote metal systems based on plasmonic waveguides,such as nanoparticle–nanowire systems,single nanowire systems,crossed nanowire systems and nanowire dimer systems,are introduced,and recent novel applications,such as sensors,plasmon-driven surface-catalyzed reactions and Raman optical activity,are also presented.Furthermore,studies of remote SERS in dielectric and organic systems based on dielectric waveguides remind us that this useful technology has additional,tremendous application prospects that have not been realized in metal systems.
基金funded by the ERA-CVD project MultiFib(01KL1904)support from the China Scholarship Council.
文摘The steady progress in medical diagnosis and treatment of diseases largely hinges on the steady development and improvement of modern imaging modalities.Raman spectroscopy has attracted increasing attention for clinical applications as it is label-free,non-invasive,and delivers molecular fingerprinting information of a sample.In combination with fiber optic probes,it also allows easy access to different body parts of a patient.However,image acquisition with fiber optic probes is currently not possible.Here,we introduce a fiber optic probe-based Raman imaging system for the real-time molecular virtual reality data visualization of chemical boundaries on a computer screen and the physical world.The approach is developed around a computer vision-based positional tracking system in conjunction with photometric stereo and augmented and mixed chemical reality,enabling molecular imaging and direct visualization of molecular boundaries of three-dimensional surfaces.The proposed approach achieves a spatial resolution of 0.5 mm in the transverse plane and a topology resolution of 0.6 mm,with a spectral sampling frequency of 10 Hz,and can be used to image large tissue areas in a few minutes,making it highly suitable for clinical tissueboundary demarcation.A variety of applications on biological samples,i.e.,distribution of pharmaceutical compounds,brain-tumor phantom,and various types of sarcoma have been characterized,showing that the system enables rapid and intuitive assessment of molecular boundaries.
文摘Redox Responsive Transcription Factor1 (RRTF1) in Arabidopsis is rapidly and transiently upregulated by H202, as well as biotic- and abiotic-induced redox signals. RRTF1 is highly conserved in angio- sperms, but its physiological role remains elusive. Here we show that inactivation of RRTF1 restricts and overexpression promotes reactive oxygen species (ROS) accumulation in response to stress. Transgenic lines overexpressing RRTF1 are impaired in root and shoot development, light sensitive, and susceptible to Alternaria brassicae infection. These symptoms are diminished by the beneficial root endophyte Piriformospora indica, which reduces ROS accumulation locally in roots and systemi- cally in shoots, and by antioxidants and ROS inhibitors that scavenge ROS. More than 800 genes were detected in mature leaves and seedlings of transgenic lines overexpressing RRTF1; ∽40% of them have stress-, redox-, ROS-regulated-, ROS-scavenging-, defense-, cell death- and related functions. Bioinformatic analyses and in vitro DNA binding assays demonstrate that RRTF1 binds to GCC-box-like sequences in the promoter of RRTFl-responsive genes. Upregulation of RRTF1 by stress stimuli and H202 requires WRKY18/40/60. RRTF1 is co-regulated with the phylogenet- ically related RAP2.6, which contains a GCC-box-like sequence in its promoter, but transgenic lines overexpressing RAP2.6 do not accumulate higher ROS levels. RRTF1 also stimulates systemic ROS accumulation in distal non-stressed leaves. We conclude that the elevated levels of the highly conserved RRTF1 induce ROS accumulation in response to ROS and ROS-producing abiotic and biotic stress signals.
基金supported by the National Natural Science Foundation of China(Grant No.81571380)the Natural Science Foundation of Zhejiang Province–China(Grant No.LY16H080009)+2 种基金supported by the National Natural Science Foundation of China(Grant Nos.81130074,81420108017,and 81525010)funded by the National Key R&D Plan from the Ministry of Science and Technology of China(Grant No.SQ2016ZY05002341)partially supported by the Deutsche Forschungsgemeinschaft(DFG),Germany
文摘Maintenance of tissue-specific stem cells is vital for organ homeostasis and organismal longevity.Hematopoietic stem cells(HSCs) are the most primitive cell type in the hematopoietic system.They divide asymmetrically and give rise to daughter cells with HSC identity(selfrenewal) and progenitor progenies(differentiation),which further proliferate and differentiate into full hematopoietic lineages.Mammalian ageing process is accompanied with abnormalities in the HSC self-renewal and differentiation.Transcriptional changes and epigenetic modulations have been implicated as the key regulators in HSC ageing process.The DNA damage response(DDR)in the cells involves an orchestrated signaling pathway,consisting of cell cycle regulation,cell death and senescence,transcriptional regulation,as well as chromatin remodeling.Recent studies employing DNA repair-deficient mouse models indicate that DDR could intrinsically and extrinsically regulate HSC maintenance and play important roles in tissue homeostasis of the hematopoietic system.In this review,we summarize the current understanding of how the DDR determines the HSC fates and finally contributes to organismal ageing.
基金Open Access funding enabled and organized by Projekt DEAL。
文摘Nature Photonics 15,813-816(2021)https://doi.org/10.1038/s41566-021-00865-0 Control of light polarization over a wide range of optical wavelengths is highly desirable within a variety of applications.Fabrication of waveplates,allowing for achromatic retardation usually requires a sophisticated combination of multiple layers of birefringent materials.