Water photoacoustic microscopy(PAM)enables water absorption contrast mapping in deep biological tissue,which further allows a more detailed architecture analysis and facilitates a better understanding of metabolic and...Water photoacoustic microscopy(PAM)enables water absorption contrast mapping in deep biological tissue,which further allows a more detailed architecture analysis and facilitates a better understanding of metabolic and pathophysiological pathways.The strongest absorption peak of water in the near-infrared region occurs at 1930 nm,where the first overtone of the O-H bond lies.However,general light sources operating in this band hitherto still suffer from low optical signal-to-noise ratio and suboptimal pulse widths for photoacoustic signal generation.These lead to not only PAM contrast deterioration but also a high risk of sample photodamage.Consequently,we developed a hybrid optical parametrically-oscillating emitter(HOPE)source for an improved water PAM image contrast,leading to noninvasive and safer bioimaging applications.Our proposed source generates 1930 nm laser pulses with high spectral purity at a repetition rate of 187.5 kHz.The pulse width is flexibly tunable from 4 to 15 ns,and the maximum pulse energy is 700 nJ with a power stability of 1.79%.Leveraging these advancements,we also demonstrated high-contrast water PAM in multifaceted application scenarios,including tracking the dynamic of water distribution in a zebrafish embryo,visualizing the water content of a murine tumor xenograft,and mapping the fluid distribution in an edema mouse ear model.Finally,we showcased 1750-nm/1930-nm dual-color PAM for quantitative imaging of lipid and water distributions with reduced cross talk and imaging artifacts.Given all these results,we believe that our HOPE source can heighten water PAM’s relevance in both biological research and clinical diagnostics.展开更多
Photoacoustic microscopy(PAM)operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biological tissues.Despite its potential,the effectiveness of lipid-bas...Photoacoustic microscopy(PAM)operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biological tissues.Despite its potential,the effectiveness of lipid-based PAM has been limited by the performance of existing nanosecond laser sources at this wavelength.In this work,we introduce a 1725-nm hybrid optical parametric oscillator emitter(HOPE)characterized by a narrow bandwidth of 1.4 nm,an optical signal-to-noise ratio(OSNR)of approximately 34 dB,and a high spectral energy density of up to 480 n J/nm.This advanced laser source significantly enhances the sensitivity of photoacoustic imaging,allowing for the detailed visualization of intrahepatic lipid distributions with an impressive maximal contrast ratio of 23.6:1.Additionally,through segmentation-based analysis of PAM images,we were able to determine steatosis levels that align with clinical assessments,thereby demonstrating the potential of our system for high-contrast,label-free lipid quantification.Our findings suggest that the proposed 1725-nm HOPE source could be a powerful tool for biomedical research and clinical diagnostics,offering a substantial improvement over current technologies in the accurate and non-invasive assessment of lipid accumulation in tissues.展开更多
Traditional conversion of alcohols into carbonyl compounds exists a few drawbacks such as harsh reaction conditions,production of large amounts of hazardous wastes,and poor selectivity.The newly emerging conversion ap...Traditional conversion of alcohols into carbonyl compounds exists a few drawbacks such as harsh reaction conditions,production of large amounts of hazardous wastes,and poor selectivity.The newly emerging conversion approaches via photo-,electro-,and photoelectro-catalysis to oxidize alcohols into high value-added corresponding carbonyl compounds as well as the possible simultaneous production of clean fuel hydrogen(H_(2))under mild conditions are promising to substitute the traditional approach to form greener and sustainable reaction systems and thus have aroused tremendous investigations.In this review,the state-of-the-art photocatalytic,electrocatalytic,and photoelectrocatalytic strategies for selective oxidation of different types of alcohols(aromatic and aliphatic alcohols,single alcohol,and polyols,etc.)as well as the simultaneous production of H_(2) in certain systems are discussed.The design of photocatalysts,electrocatalysts,and photoelectrocatalysts as well as reaction mechanism is summarized and discussed in detail.In the end,current challenges and future research directions are proposed.It is expected that this review will not only deepen the understanding of environmentally friendly catalytic systems for alcohol conversion as well as H_(2) production,but also enlighten significance and inspirations for the follow-up study of selective oxidation of various types of organic molecules to value-added chemicals.展开更多
Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO_(2) reduction by photocatalysis. In...Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO_(2) reduction by photocatalysis. Instead of the total oxidation of organics in the degradation process, the photo-oxidation of alcohols aims at the selective conversion of alcohols to produce carbonyl/acid compounds. Promising results have been achieved in designing the catalysts and reaction system, as well as in the mechanistic investigations in the past few years. This review summarizes the state-of-the-art progress in the photo-oxidation of alcohols, including the development of photocatalysts and cocatalysts, reaction conditions including the solvent and the atmosphere, and the exploration of mechanisms with scavengers experiment, electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The challenges and outlook for the further research in this field are also discussed.展开更多
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region(SAR)of China(Grant Nos.HKU 17210522,HKU C7074-21G,HKU 17205321,and HKU 17200219)ITF MHKJFS Projects(Grant Nos.MHP/073/20 and MHP/057/21)the Health@InnoHK Program of the Innovation and Technology Commission of the Hong Kong SAR Government.
文摘Water photoacoustic microscopy(PAM)enables water absorption contrast mapping in deep biological tissue,which further allows a more detailed architecture analysis and facilitates a better understanding of metabolic and pathophysiological pathways.The strongest absorption peak of water in the near-infrared region occurs at 1930 nm,where the first overtone of the O-H bond lies.However,general light sources operating in this band hitherto still suffer from low optical signal-to-noise ratio and suboptimal pulse widths for photoacoustic signal generation.These lead to not only PAM contrast deterioration but also a high risk of sample photodamage.Consequently,we developed a hybrid optical parametrically-oscillating emitter(HOPE)source for an improved water PAM image contrast,leading to noninvasive and safer bioimaging applications.Our proposed source generates 1930 nm laser pulses with high spectral purity at a repetition rate of 187.5 kHz.The pulse width is flexibly tunable from 4 to 15 ns,and the maximum pulse energy is 700 nJ with a power stability of 1.79%.Leveraging these advancements,we also demonstrated high-contrast water PAM in multifaceted application scenarios,including tracking the dynamic of water distribution in a zebrafish embryo,visualizing the water content of a murine tumor xenograft,and mapping the fluid distribution in an edema mouse ear model.Finally,we showcased 1750-nm/1930-nm dual-color PAM for quantitative imaging of lipid and water distributions with reduced cross talk and imaging artifacts.Given all these results,we believe that our HOPE source can heighten water PAM’s relevance in both biological research and clinical diagnostics.
基金Research Grants Council of the Hong Kong Special Administrative Region of China(HKU 17212824,HKU 17210522,HKU C7074-21G,HKU R7003-21,HKU 17205321)Innovation and Technology Commission of the Hong Kong SAR Government(MHP/073/20,MHP/057/21,Health@Inno HK program)Shenzhen Science Technology and Innovation Commission(SGDX20220530111403022)。
文摘Photoacoustic microscopy(PAM)operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biological tissues.Despite its potential,the effectiveness of lipid-based PAM has been limited by the performance of existing nanosecond laser sources at this wavelength.In this work,we introduce a 1725-nm hybrid optical parametric oscillator emitter(HOPE)characterized by a narrow bandwidth of 1.4 nm,an optical signal-to-noise ratio(OSNR)of approximately 34 dB,and a high spectral energy density of up to 480 n J/nm.This advanced laser source significantly enhances the sensitivity of photoacoustic imaging,allowing for the detailed visualization of intrahepatic lipid distributions with an impressive maximal contrast ratio of 23.6:1.Additionally,through segmentation-based analysis of PAM images,we were able to determine steatosis levels that align with clinical assessments,thereby demonstrating the potential of our system for high-contrast,label-free lipid quantification.Our findings suggest that the proposed 1725-nm HOPE source could be a powerful tool for biomedical research and clinical diagnostics,offering a substantial improvement over current technologies in the accurate and non-invasive assessment of lipid accumulation in tissues.
基金support from the National Natural Science Foundation of China(21976054,22176054)the Fundamental Research Funds for the Central Universities(2020MS036,FRF-TP-20-005A3)+1 种基金the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(QNXM20220026)MOE Key Laboratory of Resources and Environmental System Optimization,College of Environmental Science and Engineering,North China Electric Power University(KLRE-KF202201)。
文摘Traditional conversion of alcohols into carbonyl compounds exists a few drawbacks such as harsh reaction conditions,production of large amounts of hazardous wastes,and poor selectivity.The newly emerging conversion approaches via photo-,electro-,and photoelectro-catalysis to oxidize alcohols into high value-added corresponding carbonyl compounds as well as the possible simultaneous production of clean fuel hydrogen(H_(2))under mild conditions are promising to substitute the traditional approach to form greener and sustainable reaction systems and thus have aroused tremendous investigations.In this review,the state-of-the-art photocatalytic,electrocatalytic,and photoelectrocatalytic strategies for selective oxidation of different types of alcohols(aromatic and aliphatic alcohols,single alcohol,and polyols,etc.)as well as the simultaneous production of H_(2) in certain systems are discussed.The design of photocatalysts,electrocatalysts,and photoelectrocatalysts as well as reaction mechanism is summarized and discussed in detail.In the end,current challenges and future research directions are proposed.It is expected that this review will not only deepen the understanding of environmentally friendly catalytic systems for alcohol conversion as well as H_(2) production,but also enlighten significance and inspirations for the follow-up study of selective oxidation of various types of organic molecules to value-added chemicals.
基金This research was funded by the National Natural Science Foundation of China(21976054)the Fundamental Research Funds for the Central Universities(2020MS036)the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)within the collaborative research centre/transregio 247"Heterogeneous Oxidation Catalysis in the Liquid Phase,f.
文摘Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO_(2) reduction by photocatalysis. Instead of the total oxidation of organics in the degradation process, the photo-oxidation of alcohols aims at the selective conversion of alcohols to produce carbonyl/acid compounds. Promising results have been achieved in designing the catalysts and reaction system, as well as in the mechanistic investigations in the past few years. This review summarizes the state-of-the-art progress in the photo-oxidation of alcohols, including the development of photocatalysts and cocatalysts, reaction conditions including the solvent and the atmosphere, and the exploration of mechanisms with scavengers experiment, electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The challenges and outlook for the further research in this field are also discussed.
