In the context of this work,a prototype hybrid photoacoustic(PA)and optical system for the on-line monitoring of laser cleaning procedures is presented.The developed apparatus has enabled the detection of MHz frequenc...In the context of this work,a prototype hybrid photoacoustic(PA)and optical system for the on-line monitoring of laser cleaning procedures is presented.The developed apparatus has enabled the detection of MHz frequency range acoustic waves generated during the laser ablation process.The intrinsically generated PA signals combined with high resolution optical images provide the opportunity to follow the cleaning process accurately and in real time.Technical mock-ups have been used to demonstrate the potential of this novel technique with emphasis given to applications that refer to the restoration of Cultural Heritage(CH)surfaces.Towards this purpose,the real time monitoring of the laser assisted removal of unwanted encrustation from stonework has been achieved using IR and UV wavelengths.This novel approach has allowed for the precise determination of the critical number of laser pulses required for the elimination of the encrustation layer,while highlighting the dominant ablation mechanisms according to the irradiation wavelength.The promising results obtained using the prototype hybrid PA and optical system can open up new perspectives in the monitoring of laser cleaning interventions,promoting an improved restoration outcome.展开更多
Pluripotency of embryonic stem cells(ESCs) and induced pluripotent stem cells is regulated by a well characterized gene transcription circuitry. The circuitry is assembled by ESC specific transcription factors, signal...Pluripotency of embryonic stem cells(ESCs) and induced pluripotent stem cells is regulated by a well characterized gene transcription circuitry. The circuitry is assembled by ESC specific transcription factors, signal trans-ducing molecules and epigenetic regulators. Growing understanding of stem-like cells, albeit of more complex phenotypes, present in tumors(cancer stem cells), provides a common conceptual and research frame-work for basic and applied stem cell biology. In this review, we highlight current results on biomarkers, gene signatures, signaling pathways and epigenetic regulators that are common in embryonic and cancer stem cells. We discuss their role in determining the cell phenotype and finally, their potential use to design next generation biological and pharmaceutical approaches for regenerative medicine and cancer therapies.展开更多
The present study aims to the development of Out of Autoclave (OoA) Carbon Fiber Reinforced Polymers (CFRPs) with increased interlaminar fracture toughness by using MWCNTs. The introduction of MWCNTs into the structur...The present study aims to the development of Out of Autoclave (OoA) Carbon Fiber Reinforced Polymers (CFRPs) with increased interlaminar fracture toughness by using MWCNTs. The introduction of MWCNTs into the structure of CFRPs has been succeeded by using carbon nanotube-enriched sizing agent for the pretreatment of the fiber preform using an in-house developed methodology that can be easily scaled up. The positive effect of the proposed methodology on the interlaminar fracture toughness of the CFRP laminate was assessed by the increase of Mode I and Mode II interlaminar fracture toughness of the composites. Different wt% MWCNTs concentrations were used (namely 0.5%, 1%, 1.5% and 2.5%). It was found that the nanomodified composites exhibit a significant increase of the interlaminar critical strain energy release rate GIC and GIIC of the order of 103% and 62% respectively, in the case of 1.5 wt% MWCNTs weight content. Scanning Electron Microscopy (SEM) of the fracture surfaces of CFRP samples revealed the contribution and the associated synergistic mechanisms of MWCNTs to the increase of the crack propagation resistance in the case of nano-modified CFRPs compared to the reference material.展开更多
Photocatalysis with modified titania is a promising approach to improve both air and health quality.Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings,which ar...Photocatalysis with modified titania is a promising approach to improve both air and health quality.Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings,which are benchmark materials suitable for their indoor applications.It is generally accepted that the photocatalytic activity is affected by the light absorption,charge creation/recombination rate and surface reactivity.In this contribution we focus on modified TiO_(2) as catalyst in heterogeneous photocatalytic processes and address the efficiency of TiO_(2)-based building and construction materials on the removal of environmental pollutants indoors and outdoors.We also present data on the presence of eventually formed,toxicologically relevant and harmful by-products as the result of the photo-induced degradation of pollutants in an effort for better evaluation of induced risks for human health from the application of TiO_(2) modified materials.Finally,we present recent results on the disinfection performance of these material and the inactivation of severe pathogens contained in water and indoor air environments.展开更多
Background:The recent rise in temperature and shifting precipitation regimes threaten ecosystems around the globe to different degrees.Treelines are expected to respond to climate warming by shifting to higher elevati...Background:The recent rise in temperature and shifting precipitation regimes threaten ecosystems around the globe to different degrees.Treelines are expected to respond to climate warming by shifting to higher elevations,but it is unclear whether they can track temperature changes.Here,we integrated high-resolution aerial imagery with local climatic and topographic characteristics to study the treeline dynamic from 1945 to 2015 on the semiarid Mediterranean island of Crete,Greece.Results:During the study period,the mean annual temperature at the treeline increased by 0.81℃,while the average precipitation decreased by 170 mm.The treeline is characterized by a diffuse form,with trees growing on steep limestone slopes(>50°)and shallow soils.Moreover,the treeline elevation decreases with increasing distance from the coast and with aspect(south>north).Yet,we found no shift in the treeline over the past 70 years,despite an increase in temperature in all four study sites.However,the treeline elevation correlated strongly with topographic exposure to wind(R^(2)=0.74,p<0.001).Therefore,the temporal lag in treeline response to warming could be explained by a combination of topographic and microclimatic factors,such as the absence of a shelter effect and a decrease in moisture.Conclusion:Although there was no treeline shift over the last 70 years,climate change has already started shifting the treeline altitudinal optimum.Consequently,the lack of climate-mediated migration at the treeline should raise concerns about the threats posed by warming,such as drought damages,and wildfire,especially in the Mediterranean region.Therefore,conservation management should discuss options and needs to support adaptive management.展开更多
Recently,our group produced spin-polarized hydrogen(SPH)atoms at densities of at least 10^(19)cm^(-3)from the photodissociation of hydrogen halide molecules with circularly polarized UV light and measured them via mag...Recently,our group produced spin-polarized hydrogen(SPH)atoms at densities of at least 10^(19)cm^(-3)from the photodissociation of hydrogen halide molecules with circularly polarized UV light and measured them via magnetization-quantum beats with a pickup coil.These densities are approximately 7 orders of magnitude higher than those produced using conventional methods,opening up new fields of application,such as ultrafast magnetometry,the production of polarized MeV and GeV particle beams,such as electron beams with intensities approximately 10^(4)higher than current sources,and the study of polarized nuclear fusion,for which the reaction cross sections of D-T and D-(3)^He reactions are expected to increase by 50%for fully polarized nuclear spins.We review the production,detection,depolarization mechanisms,and potential applications of high-density SPH.展开更多
Highly-sensitive and stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr 3 microcrystals,synthesized by a facile solution process per-formed under ambient co...Highly-sensitive and stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr 3 microcrystals,synthesized by a facile solution process per-formed under ambient conditions.It is shown that such elements demonstrate enhanced room tem-perature gas sensing ability compared to the previously reported metal halide and oxide-based ones.Electrical measurements performed on these sensing components revealed high sensitivity to ultra-low ozone and hydrogen concentrations,namely 4 ppb and 1 ppm respectively,as well as a remarkable repeatability,even after a few months of storage in ambient conditions.Both ozone and hydrogen sensors were self-activated,as they did not require the use of UV or heating external stimuli to operate,and exhibited fast detection and short restoration times.All such attractive properties along with the simple fabrication process could provide an easy,efficient and low-cost technology for the realization of future gas sensing devices.展开更多
Background:As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece.Displaced populations,travelling and living under poor conditions with limited access to healthcare are at a high risk ...Background:As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece.Displaced populations,travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease(VBD).This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present,in light of designing effective and efficient context specific vector and disease control programs.Methods:A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece.Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control(CDC)light traps and oviposition traps.Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition,population dynamics,pathogen infection rates,and insecticide resistance status in the major vector species.Results:Important disease vectors including Anopheles sacharovi,Culex pipiens,Aedes albopictus and the Leishmania vectors Phlebotomus neglectus,P.perfiliewi and P.tobbi were recorded in the study refugee camps.No mosquito pathogens(Plasmodium parasites,flaviviruses)were detected in the analysed samples yet high sand fly Leishmania infection rates are reported.Culex pipiens mosquitoes displayed relatively high knock down resistance(kdr)mutation allelic frequencies(ranging from 41.0 to 63.3%)while kdr mutations were also detected in Ae.albopictus populations,but not in Anopheles and sand fly specimens.No diflubenzuron(DFB)mutations were detected in any of the mosquito species analysed.Conclusions:Important disease vectors and pathogens in vectors(Leishmania spp.)were recorded in the refugee camps indicating a situational risk factor for disease transmission.The Cx.pipiens and Ae.albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings.In contrast,pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx.pipiens and Ae.albopictus larvicide applications.Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.展开更多
All-dielectric metasurfaces offer low material loss and strong field localization and are,therefore,well suited for ultrathin and compact optical devices for electomagnetic wave manipulation at the nanoscale.All-silic...All-dielectric metasurfaces offer low material loss and strong field localization and are,therefore,well suited for ultrathin and compact optical devices for electomagnetic wave manipulation at the nanoscale.All-silicon dielectric metasurfaces,in particular,may additionally offer the desired compatibility with complementary metal-oxide semiconductor technology and,hence,are ideal candidates for large-scale monolithic integration on a photonic chip.However,in conventional silicon microfabrication approaches,the combination of mask photolithography with reactive ion etching usually involves expensive masks and multiple preprocessing stages leading to increased cost and fabrication times.In this work,a singlestep lithographical approach is proposed for the realization of all-silicon dielectric resonant metasurfaces that involves femtosecond laser processing of silicon below ablation threshold in combination with subsequent wet chemical etching.The method exploits the different etching rate between laser-modified and untreated regions,enabling large-area fabrication of patterned silicon surfaces in a facile and costefficient manufacturing approach.It is presented how two-dimensional silicon micro/nanostructures with controllable features,such as nanocones,can be effectively generated and,as a proof of concept,an allsilicon dielectric metasurface device supporting antiferromagnetic order is experimentally demonstrated.展开更多
Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide reduc...Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide reduction.Numerous inorganic semiconducting materials have been explored as photocatalysts,and the versatility of these materials and reactions has been expanded in recent years.Understanding the relationship between the physicochemical properties of photocatalytic materials and their performances as well as the fundamentals in catalytic processes is important to design and synthesis of photocatalytic materials.展开更多
文摘In the context of this work,a prototype hybrid photoacoustic(PA)and optical system for the on-line monitoring of laser cleaning procedures is presented.The developed apparatus has enabled the detection of MHz frequency range acoustic waves generated during the laser ablation process.The intrinsically generated PA signals combined with high resolution optical images provide the opportunity to follow the cleaning process accurately and in real time.Technical mock-ups have been used to demonstrate the potential of this novel technique with emphasis given to applications that refer to the restoration of Cultural Heritage(CH)surfaces.Towards this purpose,the real time monitoring of the laser assisted removal of unwanted encrustation from stonework has been achieved using IR and UV wavelengths.This novel approach has allowed for the precise determination of the critical number of laser pulses required for the elimination of the encrustation layer,while highlighting the dominant ablation mechanisms according to the irradiation wavelength.The promising results obtained using the prototype hybrid PA and optical system can open up new perspectives in the monitoring of laser cleaning interventions,promoting an improved restoration outcome.
文摘Pluripotency of embryonic stem cells(ESCs) and induced pluripotent stem cells is regulated by a well characterized gene transcription circuitry. The circuitry is assembled by ESC specific transcription factors, signal trans-ducing molecules and epigenetic regulators. Growing understanding of stem-like cells, albeit of more complex phenotypes, present in tumors(cancer stem cells), provides a common conceptual and research frame-work for basic and applied stem cell biology. In this review, we highlight current results on biomarkers, gene signatures, signaling pathways and epigenetic regulators that are common in embryonic and cancer stem cells. We discuss their role in determining the cell phenotype and finally, their potential use to design next generation biological and pharmaceutical approaches for regenerative medicine and cancer therapies.
文摘The present study aims to the development of Out of Autoclave (OoA) Carbon Fiber Reinforced Polymers (CFRPs) with increased interlaminar fracture toughness by using MWCNTs. The introduction of MWCNTs into the structure of CFRPs has been succeeded by using carbon nanotube-enriched sizing agent for the pretreatment of the fiber preform using an in-house developed methodology that can be easily scaled up. The positive effect of the proposed methodology on the interlaminar fracture toughness of the CFRP laminate was assessed by the increase of Mode I and Mode II interlaminar fracture toughness of the composites. Different wt% MWCNTs concentrations were used (namely 0.5%, 1%, 1.5% and 2.5%). It was found that the nanomodified composites exhibit a significant increase of the interlaminar critical strain energy release rate GIC and GIIC of the order of 103% and 62% respectively, in the case of 1.5 wt% MWCNTs weight content. Scanning Electron Microscopy (SEM) of the fracture surfaces of CFRP samples revealed the contribution and the associated synergistic mechanisms of MWCNTs to the increase of the crack propagation resistance in the case of nano-modified CFRPs compared to the reference material.
基金This work was carried out as part of European Funding programs under the FP7 Clear-up IP project no 211948 and FP7-Regpot-2012-2013-1 under grant agreement No 316165.
文摘Photocatalysis with modified titania is a promising approach to improve both air and health quality.Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings,which are benchmark materials suitable for their indoor applications.It is generally accepted that the photocatalytic activity is affected by the light absorption,charge creation/recombination rate and surface reactivity.In this contribution we focus on modified TiO_(2) as catalyst in heterogeneous photocatalytic processes and address the efficiency of TiO_(2)-based building and construction materials on the removal of environmental pollutants indoors and outdoors.We also present data on the presence of eventually formed,toxicologically relevant and harmful by-products as the result of the photo-induced degradation of pollutants in an effort for better evaluation of induced risks for human health from the application of TiO_(2) modified materials.Finally,we present recent results on the disinfection performance of these material and the inactivation of severe pathogens contained in water and indoor air environments.
基金We acknowledge support from the ECOPOTENTIAL project-EU Horizon 2020 research and innovation program,grant agreement no.641762.
文摘Background:The recent rise in temperature and shifting precipitation regimes threaten ecosystems around the globe to different degrees.Treelines are expected to respond to climate warming by shifting to higher elevations,but it is unclear whether they can track temperature changes.Here,we integrated high-resolution aerial imagery with local climatic and topographic characteristics to study the treeline dynamic from 1945 to 2015 on the semiarid Mediterranean island of Crete,Greece.Results:During the study period,the mean annual temperature at the treeline increased by 0.81℃,while the average precipitation decreased by 170 mm.The treeline is characterized by a diffuse form,with trees growing on steep limestone slopes(>50°)and shallow soils.Moreover,the treeline elevation decreases with increasing distance from the coast and with aspect(south>north).Yet,we found no shift in the treeline over the past 70 years,despite an increase in temperature in all four study sites.However,the treeline elevation correlated strongly with topographic exposure to wind(R^(2)=0.74,p<0.001).Therefore,the temporal lag in treeline response to warming could be explained by a combination of topographic and microclimatic factors,such as the absence of a shelter effect and a decrease in moisture.Conclusion:Although there was no treeline shift over the last 70 years,climate change has already started shifting the treeline altitudinal optimum.Consequently,the lack of climate-mediated migration at the treeline should raise concerns about the threats posed by warming,such as drought damages,and wildfire,especially in the Mediterranean region.Therefore,conservation management should discuss options and needs to support adaptive management.
基金This work is supported by the Hellenic Foundation for Research and Innovation(HFRI)and the General Secretariat for Research and Technology(GSRT),grant agreement No.HFRI-FM17-3709(project NUPOL)and by the project"HELLASCHH(MIS 5002735)Which is implemented under the"Action for Strengthening Research and Innovation Infrastructures",funded by the Operational Programme"Competitiveness,Entrepreneurship and Innovation"(NSRF 2014-2020)cofinanced by Greece and the European Union(European Regional Development Fund).GK acknowledges funding from the Hellenic Foundation for Research and Innovation(HFRI)and the General Secretariat for Research and Technology(G5RT),under project HANDCORE grant agreem ent No 1789.Figure 5 is adapted with permission from Boulogiannis et al.,"Spin-polarized hydrogen depolarization rates at high hydrogen halide pressures:hyperfine depolarization via the HY-H complex",The Journal of Physical Chemistry A 123,8130-8134(2019)。
文摘Recently,our group produced spin-polarized hydrogen(SPH)atoms at densities of at least 10^(19)cm^(-3)from the photodissociation of hydrogen halide molecules with circularly polarized UV light and measured them via magnetization-quantum beats with a pickup coil.These densities are approximately 7 orders of magnitude higher than those produced using conventional methods,opening up new fields of application,such as ultrafast magnetometry,the production of polarized MeV and GeV particle beams,such as electron beams with intensities approximately 10^(4)higher than current sources,and the study of polarized nuclear fusion,for which the reaction cross sections of D-T and D-(3)^He reactions are expected to increase by 50%for fully polarized nuclear spins.We review the production,detection,depolarization mechanisms,and potential applications of high-density SPH.
基金This work was supported by the FLAG-ERA grant PeroGaS by General Secretariat for Research and Innovation(GSRI)(MIS 5070514)K.B.acknowledges E.U.H2020 Research and Innovation Program under Grant Agreement N820677Greek State Schol-arships Foundation(IKY)through the operational Program«Human Resources Development,Education and Lifelong Learning»in the context of the project“Reinforcement of Postdoctoral Researchers-2nd Cycle”(MIS-5033021).
文摘Highly-sensitive and stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr 3 microcrystals,synthesized by a facile solution process per-formed under ambient conditions.It is shown that such elements demonstrate enhanced room tem-perature gas sensing ability compared to the previously reported metal halide and oxide-based ones.Electrical measurements performed on these sensing components revealed high sensitivity to ultra-low ozone and hydrogen concentrations,namely 4 ppb and 1 ppm respectively,as well as a remarkable repeatability,even after a few months of storage in ambient conditions.Both ozone and hydrogen sensors were self-activated,as they did not require the use of UV or heating external stimuli to operate,and exhibited fast detection and short restoration times.All such attractive properties along with the simple fabrication process could provide an easy,efficient and low-cost technology for the realization of future gas sensing devices.
基金This work was partly supported by the General Secretariat for Research and Technology (GSRT) and the Hellenic Foundation for Research and Innovation (HFRI) in the context of the action "1st Proclamation of Scholarships from ELIDEK for PhD Candidates" .
文摘Background:As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece.Displaced populations,travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease(VBD).This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present,in light of designing effective and efficient context specific vector and disease control programs.Methods:A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece.Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control(CDC)light traps and oviposition traps.Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition,population dynamics,pathogen infection rates,and insecticide resistance status in the major vector species.Results:Important disease vectors including Anopheles sacharovi,Culex pipiens,Aedes albopictus and the Leishmania vectors Phlebotomus neglectus,P.perfiliewi and P.tobbi were recorded in the study refugee camps.No mosquito pathogens(Plasmodium parasites,flaviviruses)were detected in the analysed samples yet high sand fly Leishmania infection rates are reported.Culex pipiens mosquitoes displayed relatively high knock down resistance(kdr)mutation allelic frequencies(ranging from 41.0 to 63.3%)while kdr mutations were also detected in Ae.albopictus populations,but not in Anopheles and sand fly specimens.No diflubenzuron(DFB)mutations were detected in any of the mosquito species analysed.Conclusions:Important disease vectors and pathogens in vectors(Leishmania spp.)were recorded in the refugee camps indicating a situational risk factor for disease transmission.The Cx.pipiens and Ae.albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings.In contrast,pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx.pipiens and Ae.albopictus larvicide applications.Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.
基金supported by the EU's H2020 framework program for research and innovation under the NFFA-Europe-Pilot project(Grant No.101007417).
文摘All-dielectric metasurfaces offer low material loss and strong field localization and are,therefore,well suited for ultrathin and compact optical devices for electomagnetic wave manipulation at the nanoscale.All-silicon dielectric metasurfaces,in particular,may additionally offer the desired compatibility with complementary metal-oxide semiconductor technology and,hence,are ideal candidates for large-scale monolithic integration on a photonic chip.However,in conventional silicon microfabrication approaches,the combination of mask photolithography with reactive ion etching usually involves expensive masks and multiple preprocessing stages leading to increased cost and fabrication times.In this work,a singlestep lithographical approach is proposed for the realization of all-silicon dielectric resonant metasurfaces that involves femtosecond laser processing of silicon below ablation threshold in combination with subsequent wet chemical etching.The method exploits the different etching rate between laser-modified and untreated regions,enabling large-area fabrication of patterned silicon surfaces in a facile and costefficient manufacturing approach.It is presented how two-dimensional silicon micro/nanostructures with controllable features,such as nanocones,can be effectively generated and,as a proof of concept,an allsilicon dielectric metasurface device supporting antiferromagnetic order is experimentally demonstrated.
文摘Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide reduction.Numerous inorganic semiconducting materials have been explored as photocatalysts,and the versatility of these materials and reactions has been expanded in recent years.Understanding the relationship between the physicochemical properties of photocatalytic materials and their performances as well as the fundamentals in catalytic processes is important to design and synthesis of photocatalytic materials.
