Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have b...Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have been constantly developed.In many cases,it is hard to distinguish the natural emerald from the synthetic one using the basic instruments.Therefore,with the advantage of non-destructive technique,the infrared spectroscopy has been efficiently applied for the task.In this study,to find the potential technique in FTIR spectroscopy for classifying between natural and synthetic emerald(hydrothermal and flux-grown),the observed spectra from the Attenuated Total Reflectance Radiation(ATR),Diffuse Reflectance(DRIFT),transflectance,and specular reflection techniques were compared.The result showed that the spectra obtained from the transflectance and the DRIFT techniques were similar with equal spectral qualities.Unlike the diffuse reflectance spectra,the transflectance spectra were not affected by the sample orientations.The spectral features associated with water molecule in the crystal structure were clearly observed in both the DRIFT and transflectance spectra.Although the spectral features associated with weak absorption bands of water were not observed in both the DRIFT and transflectance spectra,the position of strong absorption band at 3 800-3 500 cm^(-1) and 1 635 cm^(-1) could be detected in the ATR spectra.In addition,the lack of absorption of water between 4 000 and 3 400 cm^(-1) in flux-grown emerald samples is the clue to separate it from the natural and hydrothermal one.In the meantime,the absence of the strong absorption peaks between 2 300 and 1 400 cm^(-1) in hydrothermal emerald can differentiate it from the natural one.展开更多
Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.H...Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.展开更多
In this study, we focused on diffuse reflectance spectroscopy, a rapid and noninvasive spectroscopy technique that has considerable potential for medical diagnosis. In order to better understand and analyze the signal...In this study, we focused on diffuse reflectance spectroscopy, a rapid and noninvasive spectroscopy technique that has considerable potential for medical diagnosis. In order to better understand and analyze the signals induced by this method, we performed a series of in vivo measurements on healthy and diseased skin. Measurement sites on a human hand and feet were chosen. Some preliminary results obtained on these sites show the feasibility of this technique in clinics.展开更多
Macrovesicular Steatosis(MS)is an independent risk factor for adverse post-liver transplant(LT)outcomes.The degree of MS is intimately related to the viability of the liver graft,which in turn is crucial to the succes...Macrovesicular Steatosis(MS)is an independent risk factor for adverse post-liver transplant(LT)outcomes.The degree of MS is intimately related to the viability of the liver graft,which in turn is crucial to the success of the operation.An ideal liver graft should have no MS and most centres would find it unacceptable to use a donor liver with severe MS for LT.While a formal liver biopsy is the goldstandard diagnostic test for MS,given the logistical and time constraints it is not universally feasible.Other tests like a frozen section biopsy are plagued by issues of fallibility with reporting and sampling bias making them inferior to a liver biopsy.Hence,the development of an accurate,non-invasive,easy-to-use,handheld,real-time device for quantification of MS would fill this lacuna in the deceased donor selection process.We present the hypothesis,design and proof-ofconcept of a study,which aims to standardise and determine the feasibility and accuracy of a novel handheld device applying the principle of diffuse reflectance spectroscopy for real-time quantification of MS.展开更多
This review report represents an overview of research and development on medical hyperspectral imaging technology and its applications.Spectral imaging technology is attracting attention as a new imaging modality for ...This review report represents an overview of research and development on medical hyperspectral imaging technology and its applications.Spectral imaging technology is attracting attention as a new imaging modality for medical applications,especially in disease diagnosis and image-guided surgery.Considering the recent advances in imaging,this technology provides an opportunity for twodimensional mapping of oxygen saturation(SatO2)of blood with high accuracy,spatial spectral imaging,and its analysis and provides detection and diagnostic information about the tissue physiology and morphology.Multispectral imaging also provides information about tissue oxygenation,perfusion,and potential function during surgery.Analytical algorithm has been examined,and indication of accurate map of relative hemoglobin concentration and SatO2 can be indicated with preferable resolution and frame rate.This technology is expected to provide promising biomedical information in practical use.Several studies suggested that blood flow and SatO2 are associated with gastrointestinal disorders,particularly malignant tumor conditions.The use and analysis of spectroscopic images are expected to potentially play a role in the detection and diagnosis of these diseases.展开更多
In this paper, we are concerned with the problem of the pathwise uniqueness of one-dimensional reflected stochastic differential equations with jumps under the assumption of non-Lipschitz continuous coefficients whose...In this paper, we are concerned with the problem of the pathwise uniqueness of one-dimensional reflected stochastic differential equations with jumps under the assumption of non-Lipschitz continuous coefficients whose proof are based on the technique of local time.展开更多
La_(1-x)CoO_(3-δ)catalysts with different non-stoichiometry of lanthanum ions were synthesized by using the sol-gel method,and their catalytic performance in toluene combustion was investigated.The results showed tha...La_(1-x)CoO_(3-δ)catalysts with different non-stoichiometry of lanthanum ions were synthesized by using the sol-gel method,and their catalytic performance in toluene combustion was investigated.The results showed that the catalytic activity and stability of A-site nonstoichiometric La_(1-x)CoO_(3-δ)were improved to a certain extent compared with pure LaCoO_(3)perovskite.Among them,the La_(0.9)CoO_(3-δ)catalyst gave the best catalytic performance for toluene oxidation.It achieved 90%toluene conversion at 205℃under the conditions of a WHSV(weight hourly space velocity)of 22,500 mL/(g·hr)and a 500 ppmV-toluene concentration.Various characterization techniques were used to investigate the relationship between the structure of these catalysts and their catalytic performance.It was found that the non-stoichiometric modification of the lanthanum ion at position A in LaCoO_(3)changed the surface element state of the catalyst and increased the oxygen vacancy content,thus,combined with improved reducibility,improving toluene degradation on the catalyst.展开更多
Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method.The obtained catalysts were subjected to selective catalytic reduction of NOxwith NH_(3)(NH_(3)-S...Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method.The obtained catalysts were subjected to selective catalytic reduction of NOxwith NH_(3)(NH_(3)-SCR) performance evaluation,structural/chemical characterizations such as X-ray diffraction (XRD),N2adsorption/desorption,H_(2)temperature-programmed reduction (H_(2)-TPR),NH_(3)temperature-programmed desorption (NH_(3)-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption,NH_(3)adsorption and NO+O_(2)in situ reactions.Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with5 wt.%Cu) could be promising candidates with highly efficient NH_(3)-SCR catalytic performance,relatively low byproduct formation and excellent hydrothermal stability,although its SO_(2)poisoning tolerability needs alleviation.Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading.On one hand,Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH_(3)-SCR reactivity.On the other hand,higher Cu loading leads to depletion of Br?nsted acid centers and simultaneous formation of abundant Lewis acid centers,which facilitates NH_(4)NO_(3)reduction via NH_(3)adsorbed on Lewis acid centers,thus improving SCR reactivity.However,Cu over-introduction leads to formation of surface highly dispersed CuOx,causing unfavorable NH_(3)oxidation and inferior N2selectivity.展开更多
A layer of zinc oxide(ZnO)micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates.Samples of this layer were...A layer of zinc oxide(ZnO)micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates.Samples of this layer were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),atomic force microscopy(AFM),and ultraviolet-visible light spectroscopy.X-ray diffraction showed the high crystallinity of ZnO film and the regular arrangement of the micro-grid.The microgrid ZnO has a lower specular reflection and a higher diffuse reflection,allowing incident light to reflect two or three times to enhance the usage of light.Photocatalytic degradation experiments on methylene blue using both ZnO micro-grid and ordinary film showed that the ZnO micro-grid has better photocatalytic properties than ordinary film.The ZnO micro-grid enhanced the photocatalytic efficiency of ZnO film by 28%with a degradation time of 300 min.展开更多
Photometric stereo is a fundamental technique in computer vision known to produce 3D shape with high accuracy. It uses several input images of a static scene taken from one and the same camera position but under varyi...Photometric stereo is a fundamental technique in computer vision known to produce 3D shape with high accuracy. It uses several input images of a static scene taken from one and the same camera position but under varying illumination. The vast majority of studies in this 3D reconstruction method assume orthographic projection for the camera model.In addition, they mainly use the Lambertian reflectance model as the way that light scatters at surfaces.Thus, providing reliable photometric stereo results from real world objects still remains a challenging task. We address 3D reconstruction by use of a more realistic set of assumptions, combining for the first time the complete Blinn–Phong reflectance model and perspective projection. Furthermore, we compare two different methods of incorporating the perspective projection into our model. Experiments are performed on both synthetic and real world images; the latter do not benefit from laboratory conditions. The results show the high potential of our method even for complex real world applications such as medical endoscopy images which may include many specular highlights.展开更多
Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation meth...Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore,and SCR perfor-mance of the catalysts was investigated.The catalysts were analyzed by X-ray diffrac-tion,H_(2)-temperature-programmed reduction,Brunauer-Emmett-Teller,Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The modified siderite catalysts calcined at 450℃ mainly consist of Fe_(2)O_(3),and added Mn,W and Sb species are amorphous.3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360℃ and good N_(2) selectivity at low temperatures.In-situ DRIFTS results show NH_(4)^(+),coordinated NH_(3),NH_(2),NO_(3)^(-)species(bidentate),NO_(2)-species(nitro,nitro-nitrito,monodentate),and adsorbed NO_(2) can be discovered on the sur-face of Mn-W-Sb modified siderite catalysts,and doping of Mn will enhance adsorbed NO_(2) formation by synergistic catalysis with Fe^(3+).In addition,the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO_(2) and H_(2)O.Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Br?nsted acid sites play a role in SCR of NO by ammonia at low temperatures.The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways.The mechanism of NO,oxidized by synergistic catalysis of Fe^(3+)and Mn^(4+/3+)to form NO_(2) among three pathways,reveals the reason of high NO_(x) conversion of the catalyst at medium and low temperatures.展开更多
Cu-TDPAT(H_(6)TDPAT=2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine),a stable nanoporous metal-organic framework with rht topology,has sparked broad interest as an adsorbent for several chemical separation proces...Cu-TDPAT(H_(6)TDPAT=2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine),a stable nanoporous metal-organic framework with rht topology,has sparked broad interest as an adsorbent for several chemical separation processes.In this work,in situ synchrotron diffraction experiments followed by sequential LeBail refinements reveal that Cu-TDPAT shows unusually large anisotropic negative thermal expansion(NTE).The PASCal crystallography tool,used to analyze the magnitude of the NTE,reveals an average volumetric thermal expansion coefficientαv=-20.3 MK^(-1).This value is significantly higher than the one reported for Cu-BTC(also known as HKUST-1),which contains the same Cu-paddlewheel building unit,αv=-12 MK^(-1).In situ synchrotron single crystal X-ray diffraction and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)were employed to shed light on the NTE mechanism.Using these two methods,we were able to elucidate the three main structural motions that are responsible for the NTE effect.The more pronounced NTE behavior of Cu-TDPAT is attributed to the lower symmetry combined with the more complex ligand structure when compared to Cu-BTC.The knowledge obtained in this work is important for understanding the behavior of the adsorbent under transient variable temperature conditions in fixed adsorption beds.展开更多
As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state rea...As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state reaction process,including successive cycles of milling and sintering at high temperature,was followed to produce SZO and Sr_(0.9)La_(0.1)ZrO_(3)(SLZO)powdered ingots.Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by~25%for doped sample.A great reduction in Raman modes intensity(~60%)and an annihilation of several vibration modes were detected using Raman spectroscopy.The degree of ordering on the B-site was recorded to be higher in La-doped sample.According to ultraviolet-visible(UV-Vis)absorption,a decrease in the optical gap width(E_(g))from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge.The process of electron-hole recombination was studied using photoluminescence(PL)spectroscopy.Deconvolution of PL spectra yielded four emission bands:one green band,one blue band,and two violet bands.Highly intense violet emission atλ=393 nm approximately five times greater than that detected for pure SZO is realized as La^(3+)substitutes for Sr^(2+).Such property nominates SLZO for technological applications requiring highly intense violet emission,e.g.,light-emitting diodes.展开更多
Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanosha...Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface facets.In contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria shapes.To isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation conditions.The isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) rods.In the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the support.On the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt species.In addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on stream.The isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) surface.The Pt supported on the CeO_(2) rods is also remarkably stable with time on stream.This work demonstrates the importance of using ultra-low loadings of active metal and well-defined oxide supports to isolate interactions between single metal atoms and oxide supports and determine the effects of the oxide support surface facet on the active metal at the atomic level.展开更多
文摘Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have been constantly developed.In many cases,it is hard to distinguish the natural emerald from the synthetic one using the basic instruments.Therefore,with the advantage of non-destructive technique,the infrared spectroscopy has been efficiently applied for the task.In this study,to find the potential technique in FTIR spectroscopy for classifying between natural and synthetic emerald(hydrothermal and flux-grown),the observed spectra from the Attenuated Total Reflectance Radiation(ATR),Diffuse Reflectance(DRIFT),transflectance,and specular reflection techniques were compared.The result showed that the spectra obtained from the transflectance and the DRIFT techniques were similar with equal spectral qualities.Unlike the diffuse reflectance spectra,the transflectance spectra were not affected by the sample orientations.The spectral features associated with water molecule in the crystal structure were clearly observed in both the DRIFT and transflectance spectra.Although the spectral features associated with weak absorption bands of water were not observed in both the DRIFT and transflectance spectra,the position of strong absorption band at 3 800-3 500 cm^(-1) and 1 635 cm^(-1) could be detected in the ATR spectra.In addition,the lack of absorption of water between 4 000 and 3 400 cm^(-1) in flux-grown emerald samples is the clue to separate it from the natural and hydrothermal one.In the meantime,the absence of the strong absorption peaks between 2 300 and 1 400 cm^(-1) in hydrothermal emerald can differentiate it from the natural one.
基金the National Natural Science Foundation of China(Project Nos.21805139,21905023,12102194,22005144 and 22005145)the Joint Funds of the National Natural Science Foundation of China(Grant No.U2141202)+2 种基金Natural Science Foundation of Jiangsu Province(Grant No.BK20200471)the Fundamental Research Funds for the Central Universities(Grant Nos.30920041106,30921011203)Young Elite Scientists Sponsorship Program by CAST(Program,2021QNRC001).
文摘Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.
文摘In this study, we focused on diffuse reflectance spectroscopy, a rapid and noninvasive spectroscopy technique that has considerable potential for medical diagnosis. In order to better understand and analyze the signals induced by this method, we performed a series of in vivo measurements on healthy and diseased skin. Measurement sites on a human hand and feet were chosen. Some preliminary results obtained on these sites show the feasibility of this technique in clinics.
文摘Macrovesicular Steatosis(MS)is an independent risk factor for adverse post-liver transplant(LT)outcomes.The degree of MS is intimately related to the viability of the liver graft,which in turn is crucial to the success of the operation.An ideal liver graft should have no MS and most centres would find it unacceptable to use a donor liver with severe MS for LT.While a formal liver biopsy is the goldstandard diagnostic test for MS,given the logistical and time constraints it is not universally feasible.Other tests like a frozen section biopsy are plagued by issues of fallibility with reporting and sampling bias making them inferior to a liver biopsy.Hence,the development of an accurate,non-invasive,easy-to-use,handheld,real-time device for quantification of MS would fill this lacuna in the deceased donor selection process.We present the hypothesis,design and proof-ofconcept of a study,which aims to standardise and determine the feasibility and accuracy of a novel handheld device applying the principle of diffuse reflectance spectroscopy for real-time quantification of MS.
文摘This review report represents an overview of research and development on medical hyperspectral imaging technology and its applications.Spectral imaging technology is attracting attention as a new imaging modality for medical applications,especially in disease diagnosis and image-guided surgery.Considering the recent advances in imaging,this technology provides an opportunity for twodimensional mapping of oxygen saturation(SatO2)of blood with high accuracy,spatial spectral imaging,and its analysis and provides detection and diagnostic information about the tissue physiology and morphology.Multispectral imaging also provides information about tissue oxygenation,perfusion,and potential function during surgery.Analytical algorithm has been examined,and indication of accurate map of relative hemoglobin concentration and SatO2 can be indicated with preferable resolution and frame rate.This technology is expected to provide promising biomedical information in practical use.Several studies suggested that blood flow and SatO2 are associated with gastrointestinal disorders,particularly malignant tumor conditions.The use and analysis of spectroscopic images are expected to potentially play a role in the detection and diagnosis of these diseases.
基金supported by the National Natural Science Foundation of China (No.12261038, 11671408 and11871484)Natural Science Foundation of Jiangxi Province (No.20232BAB201004, 20212BAB201009)Training Program of Young Talents for academic and technical leaders of major disciplines in Jiangxi Province(No.20204BCJL23057)。
文摘In this paper, we are concerned with the problem of the pathwise uniqueness of one-dimensional reflected stochastic differential equations with jumps under the assumption of non-Lipschitz continuous coefficients whose proof are based on the technique of local time.
基金support from National Key Research and Development Program of China(No.2019YFC1903903)the National Natural Science Foundation of China(No.21876019)+1 种基金Fundamental Research Funds for the Central Universities(No.DUT20RC(4)003)Natural Science Foundation of Liaoning Province(No.2020-BS-056).
文摘La_(1-x)CoO_(3-δ)catalysts with different non-stoichiometry of lanthanum ions were synthesized by using the sol-gel method,and their catalytic performance in toluene combustion was investigated.The results showed that the catalytic activity and stability of A-site nonstoichiometric La_(1-x)CoO_(3-δ)were improved to a certain extent compared with pure LaCoO_(3)perovskite.Among them,the La_(0.9)CoO_(3-δ)catalyst gave the best catalytic performance for toluene oxidation.It achieved 90%toluene conversion at 205℃under the conditions of a WHSV(weight hourly space velocity)of 22,500 mL/(g·hr)and a 500 ppmV-toluene concentration.Various characterization techniques were used to investigate the relationship between the structure of these catalysts and their catalytic performance.It was found that the non-stoichiometric modification of the lanthanum ion at position A in LaCoO_(3)changed the surface element state of the catalyst and increased the oxygen vacancy content,thus,combined with improved reducibility,improving toluene degradation on the catalyst.
基金supported by the Key Program of Science Technology Department of Zhejiang Province (No.2018C03037)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (No.20KJB610005)+2 种基金the Natural Science Foundation of Jiangsu Province (Nos.BK20201037,BK20190705)Key Research and Development Program of Anhui Province (No.202104g01020006)the Scientific Research Fund of Nanjing Institute of Technology (Nos.YKJ2019111 and YKJ2019110)。
文摘Series of Cu-USY zeolite catalyst with different Cu loading content were synthesized through simple impregnation method.The obtained catalysts were subjected to selective catalytic reduction of NOxwith NH_(3)(NH_(3)-SCR) performance evaluation,structural/chemical characterizations such as X-ray diffraction (XRD),N2adsorption/desorption,H_(2)temperature-programmed reduction (H_(2)-TPR),NH_(3)temperature-programmed desorption (NH_(3)-TPD) as well as detailed in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments including CO adsorption,NH_(3)adsorption and NO+O_(2)in situ reactions.Results show that Cu-USY with proper Cu loading (in this work 5Cu-USY with5 wt.%Cu) could be promising candidates with highly efficient NH_(3)-SCR catalytic performance,relatively low byproduct formation and excellent hydrothermal stability,although its SO_(2)poisoning tolerability needs alleviation.Further characterizations reveal that such catalytic advantages can be attributed to both active cu species and surface acid centers evolution modulated by Cu loading.On one hand,Cu species in the super cages of zeolites increases with higher Cu content and being more conducive for NH_(3)-SCR reactivity.On the other hand,higher Cu loading leads to depletion of Br?nsted acid centers and simultaneous formation of abundant Lewis acid centers,which facilitates NH_(4)NO_(3)reduction via NH_(3)adsorbed on Lewis acid centers,thus improving SCR reactivity.However,Cu over-introduction leads to formation of surface highly dispersed CuOx,causing unfavorable NH_(3)oxidation and inferior N2selectivity.
基金the National Natural Science Foundation of China(Grant Nos.50672003 and 50872005)the National Basic Research Program of China(Grant No.2007CB613302)the Fok Ying-Tong Education Foundation(No.111050).
文摘A layer of zinc oxide(ZnO)micro-grid was deposited on the surface of ZnO film using the DC reactive magnetron sputtering method and the micro-sphere lithography technique on glass substrates.Samples of this layer were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),atomic force microscopy(AFM),and ultraviolet-visible light spectroscopy.X-ray diffraction showed the high crystallinity of ZnO film and the regular arrangement of the micro-grid.The microgrid ZnO has a lower specular reflection and a higher diffuse reflection,allowing incident light to reflect two or three times to enhance the usage of light.Photocatalytic degradation experiments on methylene blue using both ZnO micro-grid and ordinary film showed that the ZnO micro-grid has better photocatalytic properties than ordinary film.The ZnO micro-grid enhanced the photocatalytic efficiency of ZnO film by 28%with a degradation time of 300 min.
基金supported by the Deutsche Forschungsgemeinschaft under grant number BR2245/4–1
文摘Photometric stereo is a fundamental technique in computer vision known to produce 3D shape with high accuracy. It uses several input images of a static scene taken from one and the same camera position but under varying illumination. The vast majority of studies in this 3D reconstruction method assume orthographic projection for the camera model.In addition, they mainly use the Lambertian reflectance model as the way that light scatters at surfaces.Thus, providing reliable photometric stereo results from real world objects still remains a challenging task. We address 3D reconstruction by use of a more realistic set of assumptions, combining for the first time the complete Blinn–Phong reflectance model and perspective projection. Furthermore, we compare two different methods of incorporating the perspective projection into our model. Experiments are performed on both synthetic and real world images; the latter do not benefit from laboratory conditions. The results show the high potential of our method even for complex real world applications such as medical endoscopy images which may include many specular highlights.
基金This work was supported by the National Natural Science Foundation of China(Nos.51406077 and 51276039).
文摘Iron-based catalysts have been explored for selective catalytic reduction(SCR)of NO due to environmentally benign characters and good SCR activity.Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore,and SCR perfor-mance of the catalysts was investigated.The catalysts were analyzed by X-ray diffrac-tion,H_(2)-temperature-programmed reduction,Brunauer-Emmett-Teller,Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The modified siderite catalysts calcined at 450℃ mainly consist of Fe_(2)O_(3),and added Mn,W and Sb species are amorphous.3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360℃ and good N_(2) selectivity at low temperatures.In-situ DRIFTS results show NH_(4)^(+),coordinated NH_(3),NH_(2),NO_(3)^(-)species(bidentate),NO_(2)-species(nitro,nitro-nitrito,monodentate),and adsorbed NO_(2) can be discovered on the sur-face of Mn-W-Sb modified siderite catalysts,and doping of Mn will enhance adsorbed NO_(2) formation by synergistic catalysis with Fe^(3+).In addition,the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO_(2) and H_(2)O.Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Br?nsted acid sites play a role in SCR of NO by ammonia at low temperatures.The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways.The mechanism of NO,oxidized by synergistic catalysis of Fe^(3+)and Mn^(4+/3+)to form NO_(2) among three pathways,reveals the reason of high NO_(x) conversion of the catalyst at medium and low temperatures.
基金the Swiss National Science Foundation under Grant PYAPP2_160581.M.A.acknowledges the Swiss Commission for Technology and Innovation(CTI)(the SCCER EIP-Efflciency of Industrial Processes)for financial support.We also acknowledge the Swiss-Norwegian Beam Line BM01 at European Synchrotron Radiation Facility(ESRF)for the beamtime allocation and Dr.D m itry Chernyshov,Dr.Iurii Dovgaliuk,Dr.Olga Trukhina and Mr.Vikram Karve for the assistance on the beamline,BM01.M.A.also thanks Dr.Pascal Schouwink for assistance on X-ray diffraction experiments at EPFL Valais.
文摘Cu-TDPAT(H_(6)TDPAT=2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine),a stable nanoporous metal-organic framework with rht topology,has sparked broad interest as an adsorbent for several chemical separation processes.In this work,in situ synchrotron diffraction experiments followed by sequential LeBail refinements reveal that Cu-TDPAT shows unusually large anisotropic negative thermal expansion(NTE).The PASCal crystallography tool,used to analyze the magnitude of the NTE,reveals an average volumetric thermal expansion coefficientαv=-20.3 MK^(-1).This value is significantly higher than the one reported for Cu-BTC(also known as HKUST-1),which contains the same Cu-paddlewheel building unit,αv=-12 MK^(-1).In situ synchrotron single crystal X-ray diffraction and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)were employed to shed light on the NTE mechanism.Using these two methods,we were able to elucidate the three main structural motions that are responsible for the NTE effect.The more pronounced NTE behavior of Cu-TDPAT is attributed to the lower symmetry combined with the more complex ligand structure when compared to Cu-BTC.The knowledge obtained in this work is important for understanding the behavior of the adsorbent under transient variable temperature conditions in fixed adsorption beds.
基金the Grants Commission of Al-Azhar University,Cairo,Egypt for supporting this work。
文摘As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state reaction process,including successive cycles of milling and sintering at high temperature,was followed to produce SZO and Sr_(0.9)La_(0.1)ZrO_(3)(SLZO)powdered ingots.Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by~25%for doped sample.A great reduction in Raman modes intensity(~60%)and an annihilation of several vibration modes were detected using Raman spectroscopy.The degree of ordering on the B-site was recorded to be higher in La-doped sample.According to ultraviolet-visible(UV-Vis)absorption,a decrease in the optical gap width(E_(g))from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge.The process of electron-hole recombination was studied using photoluminescence(PL)spectroscopy.Deconvolution of PL spectra yielded four emission bands:one green band,one blue band,and two violet bands.Highly intense violet emission atλ=393 nm approximately five times greater than that detected for pure SZO is realized as La^(3+)substitutes for Sr^(2+).Such property nominates SLZO for technological applications requiring highly intense violet emission,e.g.,light-emitting diodes.
基金supported by the National Science Foundation(NSF)(CHE-1507230 and CBET-1933723)the National High Magnetic Field Laboratory,which is supported by the NSF Cooperative Agreement(DMR-1644779)and the State of Florida.Startup funding from the University of Florida is also gratefully acknowledged.
文摘Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface facets.In contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria shapes.To isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation conditions.The isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) rods.In the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the support.On the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt species.In addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on stream.The isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) surface.The Pt supported on the CeO_(2) rods is also remarkably stable with time on stream.This work demonstrates the importance of using ultra-low loadings of active metal and well-defined oxide supports to isolate interactions between single metal atoms and oxide supports and determine the effects of the oxide support surface facet on the active metal at the atomic level.
