In the preparation of this precursor tetraethlortho silicate (TEOS), sodium tungstate, ethyl alcohol, HCl and RECl3(RE=Eu,Tb) were mixed and then heated at 800 ℃ for 2 h, leading to a luminescent compound. The struct...In the preparation of this precursor tetraethlortho silicate (TEOS), sodium tungstate, ethyl alcohol, HCl and RECl3(RE=Eu,Tb) were mixed and then heated at 800 ℃ for 2 h, leading to a luminescent compound. The structure of the materials was characterized by TG-DTA and IR analysis, and the results indicate that the materials were in SiO2 network structure. Three-dimensional fluorescence spectra was used to characterize the luminescent properties of the materials. The luminescence property of doped and un-doped Eu3+or Tb3+ and Na2WO4 in silica materials were prepared and measured. The results show that good energy transfer from WO2-4 to Eu3+ ion, sensitized the luminescence intensity of Eu3+ remarkably. Tb3+ ion incorporated silica materials expressed the inverse energy transition from Tb3+ to WO2-4, however, we got the materials with homogeneous green blue fluorescent light. Finally, the energy transfer of WO2-4 and Eu3+, WO2-4 and Tb3+ were explained by energy levels diagram.展开更多
Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,...Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,10-100 kDa and 1-10 kDa retentate and <1 kDa ultrafiltrate fractions.The fluorescence properties of different molecular weights of dissolved organic matter(DOM) were measured by excitation-emission matrix spectra.Protein-like and humic-like fluorophores were observed in the DOM produced by P.donghaiense.The central positions of protein-like fluorophores showed a red shift with prolonged growth duration,shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages.The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size,but showed little change in the decline stage.However,the emission wavelengths in the decline stage exhibited a blue shift.Very distinct C type and A type peaks in humic-like fluorophores were observed.With a prolonged culture time,the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift,while the A:C ratios fell.More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.展开更多
The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical ...The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical devices,3D-XRF analysis with a micro confocal volume will create a great potential for 2D and 3D microstructural analysis and accurate quantitative analysis.However,the classic measurement method of scanning metal foils of a certain thickness leads to inaccuracy.A method for calibrating the confocal volume is proposed in this paper.The new method is based on the basic content of the textbook,and the theoretical results and the feasibility are given in detail for the 3D-XRF mono-chromatic x-ray condition and the poly-chromatic x-ray condition.We obtain a set of experimental confirmation using the poly-chromatic x-ray tube in the laboratory.It is proved that the sensitivity factor of the 3D-XRF can be directly and accurately obtained in a real calibration process.展开更多
A new supramolecular compound, { [2-(2-pyridyl)benzimidazoleH2]2+.[SBC15]2-}2, was synthesized by the hydrothermal reaction of o-diaminobenzene, 2-pyridinecarboxylie acid and SbCl3 in 1:1 HC1 solution, and charact...A new supramolecular compound, { [2-(2-pyridyl)benzimidazoleH2]2+.[SBC15]2-}2, was synthesized by the hydrothermal reaction of o-diaminobenzene, 2-pyridinecarboxylie acid and SbCl3 in 1:1 HC1 solution, and characterized by chemical analysis, elemental analysis, IR spectra, thermogravimetfic analysis and fluorescence spectra. The crystal structure was deter- mined by X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P211c, with a = 16.0397(13), b = 14.3189(12), c = 15.6370(13) A, β = 105.8980(10)°, V = 3454.0(5) A3, Z = 4, C24H22Cl10N6Sb2, Mr = 992.48, Dc = 1.909 g/cm3,/z = 2.366 mm-1, S = 1.010, F(000) = 1920, R = 0.0254 and wR = 0.0555. The coordination anion, [SbCl5]2- which is a distorted tetragonal pyramid, is composed by coordinating action with Sb3+ ion and five adjacent chloride ions. Every four coordination anions of [SbCl5]2- form a biquaternion ring structure through the secondary bonding of Sb...Cl. Moreover, the compound adopts a three-dimensional network supramolecular structure because of the hydrogen bonds and π-π stacking between the rings and the 2-(2-pyridyl)benzimidazole divalent cations. The title compound also shows good fluorescent behaviors.展开更多
Tryptophan(Trp) residues in a pullulanase were modified by N-bromosuccinimide(NBS). The results of the Spande method indicate that there are 18 Trp residues in the pullulanase and nine of them are located on the s...Tryptophan(Trp) residues in a pullulanase were modified by N-bromosuccinimide(NBS). The results of the Spande method indicate that there are 18 Trp residues in the pullulanase and nine of them are located on the surface af the enzyme. Three of these Trp residues are nonessential residues which show the fastest reaction rate according to the Zou's plot. Two of the seven relative faster reacting residues are essential for the activity of the enzyme. The other eight are the slowest in the reaction rate or non-reactive residues for the reaction. The fluorescence and circular dichroism(CD) spectra of the pullulanase have been changed after the reaction with NBS. Potassium iodide(KI) and acrylamide also have remarkable influences on the fluorescence spectra of the pullulanase.展开更多
The steady-state fluorescence spectrum characteristic of ethanol-water excimer has been studied in this paper. By analysing the features of the sharp emission spectrum with fine structures in a shortwave band and the ...The steady-state fluorescence spectrum characteristic of ethanol-water excimer has been studied in this paper. By analysing the features of the sharp emission spectrum with fine structures in a shortwave band and the characteristics of the broad and featureless fluorescence peaks in the longwave band, one can conclude that the excimers are formed between the new ethanol-water cluster molecules in the excited state and the ground state through the interaction among different chromophores. The excitation spectra in the two fluorescence bands have been studied, and their emission mechanisms have been ascertained based on the energy transfer theory. Furthermore, the critical distance of the resonance energy transfer has been calculated.展开更多
Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modula...Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modulated.The experiment results show that the signal to noise ratio has been improved by 32.64 dB when the modulation depth(converted to laser frequency)and frequency are optimized to 4 MHz and 6 kHz,respectively.This technique enables us to perform a highly sensitive non-destructive detection of Rydberg atoms.展开更多
The full-spectrum least-squares(FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples.Based on the conventional least-squares principle, this spectr...The full-spectrum least-squares(FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples.Based on the conventional least-squares principle, this spectrum evaluation method is able to obtain the background-corrected and interference-free net peaks, which is significant for quantization analyses. A variety of analytical parameters and functions to describe the features of the fluorescence spectra of pure elements are used and established, such as the mass absorption coefficient, the Gi factor, and fundamental fluorescence formulas. The FSLS iterative program was compiled in the C language. The content of each component should reach the convergence criterion at the end of the calculations. After a basic theory analysis and experimental preparation, 13 national standard soil samples were detected using a spectrometer to test the feasibility of using the algorithm. The results show that the calculated contents of Ti, Fe, Ni, Cu, and Zn have the same changing tendency as the corresponding standard content in the 13 reference samples. Accuracies of 0.35% and 14.03% are obtained, respectively, for Fe and Ti, whose standard concentrations are 8.82% and 0.578%, respectively. However, the calculated results of trace elements (only tens of lg/g) deviate from the standard values. This may be because of measurement accuracy and mutual effects between the elements.展开更多
The amino acid composition of the superoxide dismutase(SOD) from camellia pollen was measured and the tryptophan(Trp) residues were modified by using N-bromosuccinimide(NBS). The results show that there are 21 T...The amino acid composition of the superoxide dismutase(SOD) from camellia pollen was measured and the tryptophan(Trp) residues were modified by using N-bromosuccinimide(NBS). The results show that there are 21 Trp residues in an SOD molecule and seven of which are located on the surface of the enzyme. By researching the fluorescence spectra of the native SOD and the modified SOD, we have found that the emission wavelength of Trp is at 335 nm and the fluorescence intensity will decrease when the enzyme is modified. The results also show that potassium iodide(KI) can significantly quench the fluorescence of the native SOD, but it has a less pronounced effect on the modified enzyme. Glycerin as a surface activation reagent can stabilize the fluorescence of the modified enzyme.展开更多
Tryptophan residues in hyaluronidase (HAase) were modified by N-bromosuccinimide (NBS), the results indicated that there were eleven tryptophan residues in HAase, one of which was exposed and essential for the act...Tryptophan residues in hyaluronidase (HAase) were modified by N-bromosuccinimide (NBS), the results indicated that there were eleven tryptophan residues in HAase, one of which was exposed and essential for the activity of the enzyme. The study on fluorescence quenching showed that KI could not quench all of the fluorescence from Trp residues in HAase, while acrylamide (Acr) could quench almost all of the fluorescence from Trp residues in HAase. The collisional quenching constants (KD) of HAase at different concentrations of Acr were calculated in terms of Stern-Volmer equation. The results implied that some of the Trp residues were buried in the interior of HAase and the Trp residue on the surface of HAase was not located in the hydrophobic pocket.展开更多
The suppression of diorganogermanium compounds on the Maillard reaction of histidine(His) and glycine (Gly) with glucose has been determined by fluorescence spectrum underphysiological conditions. The title compounds ...The suppression of diorganogermanium compounds on the Maillard reaction of histidine(His) and glycine (Gly) with glucose has been determined by fluorescence spectrum underphysiological conditions. The title compounds show inhibition for the fluorescence intensity (FI) ofglycosylated andno acids stronger than Ge-132.展开更多
Objective:To set up a database of three-dimensional fluorescence spectra of traditional Chinese medicines,Screening of medicinal materials by three-dimensional fluorescence spectroscopy,Methods:The paper Summarizes th...Objective:To set up a database of three-dimensional fluorescence spectra of traditional Chinese medicines,Screening of medicinal materials by three-dimensional fluorescence spectroscopy,Methods:The paper Summarizes the three-dimensional fluorescence fingerprints,screens medicinal materials on basis of verifying the three-dimensional fluorescence spectra of the reference crude herbs of the national standard Chinese medicines,and combines with visual basic6.0 and microsoft access 2003 technology system to construct a three-dimensional fluorescence fingerprint database of TCMs.Results:the identification and quality control of traditional Chinese medicines(TCMs)was accuately and swiftly achieved.Conclusion:The relevant analysis on the operating system of database and the three-dimensional fluorescence spectrum database of TCMs indicates that this operating system can provide convenient channels for the inspection,verification and quality control of TCMs.展开更多
Phenylcarboxymethyl Sulfoxide, PhSOCH 2COOH(LH), complexes of six lanthanide nitrates: Ln 2L 2(NO 3) 4·2LH· n H 2O(where Ln=La, Ce, Pr, Nd, Sm, Eu) were synthesized. Elemental analyses, molar conduc...Phenylcarboxymethyl Sulfoxide, PhSOCH 2COOH(LH), complexes of six lanthanide nitrates: Ln 2L 2(NO 3) 4·2LH· n H 2O(where Ln=La, Ce, Pr, Nd, Sm, Eu) were synthesized. Elemental analyses, molar conductivities, IR, 1HNMR and TG DTA measurements were used to characterize the complexes. The results show that the ligand(L) is coordinated to metal ions through two oxygen atoms of the carboxyl group and one oxygen atom of the sulfoxide moieties. Neutral ligang (LH)is coordinated to two metal ions through two oxygen atoms of carboxyl group as an asymmetrical bridging bidentate. The fluorescence spectra of Eu 3+ complex indicates that there is no inversion symmetry at the site of Eu 3+ ion, but the emission intensity of fluorescence is quite good.The solubility of the complexes is very good in water.展开更多
The excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate phytoplankton populations at phylum level in vivo and in situ within a few minutes.The investigated phytoplankton divisions (Din...The excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate phytoplankton populations at phylum level in vivo and in situ within a few minutes.The investigated phytoplankton divisions (Dinophyta,Bacillariophyta,Chrysophyta,Cyanophyta,Cryptophyta,Chlorophyta) are each characterized by a specific composition of photosynthetic antenna pigments and,consequently,by a specific excitation spectrum of the Chl fluorescence.Norm excitation spectra (emission of 680 nm and excitation of 400–600 nm) of every division were obtained from several species per division by a F4500 fluorescence spectrophotometer.Fisher’s linear discriminant analysis of the norm spectra shows that the divisions could be discriminated.The discrimination method,established by multivariate linear regression and weighted least squares,was used to differentiate the phytoplankton samples cultured in the laboratory and samples collected from the Jiaozhao Bay at division level.The correctly discriminated samples were more than 94% for single algal species ones,more than 84% for simulatively mixed ones,more than 83% for real mixed ones and 100% for samples collected from the Jiaozhou Bay for the dominant species.The method for phytoplankton differentiation described here can be applied to routine checking by fluorescence spectrophotometer,and benefit the monitoring and supervision tasks related to phytoplankton populations in the marine environments.展开更多
A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3+-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence...A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3+-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3+. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3+-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.展开更多
A Multi-channel Oceanographic Fluorescence Lidar(MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll-a(Chl-a), has been develope...A Multi-channel Oceanographic Fluorescence Lidar(MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll-a(Chl-a), has been developed using the Laser- induced Fluorescence(LIF) technique. The sketch of the MOFL system equipped with a compact multi-channel photomultiplier tube(MPMT) is introduced in the paper. The methods of differentiating the oil fluorescence from the background water fluorescence and evaluating the Chl-a concentration are described. Two field experiments were carried out to investigate the field performance of the system, i.e., an experiment in coastal areas for oil pollution detection and an experiment over the Yellow Sea for Chl-a monitoring. In the coastal experiment, several oil samples and other fluorescence substances were used to analyze the fluorescence spectral characteristics for oil identification, and to estimate the thickness of oil films at the water surface. The experiment shows that both the spectral shape of fluorescence induced from surface water and the intensity ratio of two channels(I495/I405) are essential to determine oil-spill occurrence. In the airborne experiment, MOFL was applied to measure relative Chl-a concentrations in the upper layer of the ocean. A comparison of relative Chl-a concentration measurements by MOFL and the Moderate Resolution Imaging Spectroradiometer(MODIS) indicates that the two datasets are in good agreement. The results show that the MOFL system is capable of monitoring oil spills and Chl-a in the upper layer of ocean water.展开更多
Sensitivity is crucially important for surface-enhanced Raman spectroscopy(SERS)application to detect trace-level polycyclic aromatic hydrocarbons(PAHs)in the seawater.In this study,a high sensitivity three-dimensiona...Sensitivity is crucially important for surface-enhanced Raman spectroscopy(SERS)application to detect trace-level polycyclic aromatic hydrocarbons(PAHs)in the seawater.In this study,a high sensitivity three-dimensional(3-D)SERS substrate composed with syringe filter,glycidyl methacrylate-ethylene dimethacrylate(GMA-EDMA)porous material and optimal parameters(57 nm,pH 13)gold nanoparticles(Au NPs)was developed for the detection of PAHs in water.The enhancement effect and repeatability of this 3-D substrate were also explored.The Raman intensity of pyrene using 3-D SERS substrate is about 8 times higher than that of substrate only using p H 13 gold colloid solution and about 12 times higher than that of substrate using natural Au NPs and GMA-EDMA porous material,which means both the pH 13 AuN Ps and the GMA-EDMA porous material are important factors for the sensitivity of this 3-D SERS substrate.Good repeatability of this optimal 3-D substrate was obtained.The relative standard deviation(RSD)is less than 8.66% on the same substrate and less than 3.69% on other different substrates.Four kinds of PAHs,i.e.,phenanthrene,pyrene,benzo(a)pyrene,benzo(k)fluoranthene and their mixture,were detected at the different concentrations.Their limits of detection(LODs)are 8.3×10^-10(phenanthrene),2.1×10^-10(pyrene),3.8×10^-10(benzo(a)pyrene)and 1.7×10^-10 mol L^-1(benzo(k)fluoranthene),respectively.In addition,these four PAHs were also detected by fluorescence spectroscopy to evaluate the sensitivity of SERS technology using this optimal 3-D SERS substrate.The results showed that the sensitivity of SERS based on the 3-D SERS substrate even using the portable Raman system was closed to that of fluorescence spectroscopy.Therefore,the SERS technology using this optimal 3-D substrate is expected to be an in-situ method for the detection of environmental PAHs.展开更多
Fluoro-ruby was injected into the posterior funiculus of the spinal cord in the cervical (C5-T2) and lumbar (L3-6) segments of adult guinea pigs. The spinal cord was cut into serial frozen sections. The Fluoro-rub...Fluoro-ruby was injected into the posterior funiculus of the spinal cord in the cervical (C5-T2) and lumbar (L3-6) segments of adult guinea pigs. The spinal cord was cut into serial frozen sections. The Fluoro-ruby labeling was clearly delineated from the surrounding structure. The labeling traversed the cervical, thoracic and lumbar segments, and was located on the ventral portion of the posterior funiculus on the injected side, proximal to the intermediate zone of the dorsal gray matter. The fluorescence area narrowed rostro-caudally. The spinal cord, spinal cord gray matter and corticospinal tract were reconstructed using 3D-DOCTOR 4.0 software, resulting in a robust three-dimensional profile. Using functionality provided by the reconstruction software, free multi-angle observation and sectioning could be conducted on the spinal cord and corticospinal tract. Our experimental findings indicate that the Fluoro-ruby retrograde fluorescent tracing technique can accurately display the anatomical location of corticospinal tract in the guinea pig and that three-dimensional reconstruction software can be used to provide a three-dimensional image of the corticospinal tract.展开更多
基金Project supported by State Natural Science Foundation (20161001)Natural Science Foundation of Inner Mongolia Autonomous Region Science Commission (200508010206)
文摘In the preparation of this precursor tetraethlortho silicate (TEOS), sodium tungstate, ethyl alcohol, HCl and RECl3(RE=Eu,Tb) were mixed and then heated at 800 ℃ for 2 h, leading to a luminescent compound. The structure of the materials was characterized by TG-DTA and IR analysis, and the results indicate that the materials were in SiO2 network structure. Three-dimensional fluorescence spectra was used to characterize the luminescent properties of the materials. The luminescence property of doped and un-doped Eu3+or Tb3+ and Na2WO4 in silica materials were prepared and measured. The results show that good energy transfer from WO2-4 to Eu3+ ion, sensitized the luminescence intensity of Eu3+ remarkably. Tb3+ ion incorporated silica materials expressed the inverse energy transition from Tb3+ to WO2-4, however, we got the materials with homogeneous green blue fluorescent light. Finally, the energy transfer of WO2-4 and Eu3+, WO2-4 and Tb3+ were explained by energy levels diagram.
基金Supported by the High Technology Research and Development Program of China (863 Program) (Nos 2006AA09Z180 and 2004AA639790)the National Natural Science Foundation of China (No 40106013)the National Basic Research Program of China (973 Program) (No 2001CB409703)
文摘Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth,stationary and decline stages into <0.45 μm filtrate,100 kDa-0.45 μm,10-100 kDa and 1-10 kDa retentate and <1 kDa ultrafiltrate fractions.The fluorescence properties of different molecular weights of dissolved organic matter(DOM) were measured by excitation-emission matrix spectra.Protein-like and humic-like fluorophores were observed in the DOM produced by P.donghaiense.The central positions of protein-like fluorophores showed a red shift with prolonged growth duration,shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages.The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size,but showed little change in the decline stage.However,the emission wavelengths in the decline stage exhibited a blue shift.Very distinct C type and A type peaks in humic-like fluorophores were observed.With a prolonged culture time,the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift,while the A:C ratios fell.More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11675019 and 11875087).
文摘The measurement of the confocal volume of a confocal three-dimensional micro-x-ray fluorescence(3D-XRF)setup is a key step in the field of confocal 3D-XRF analysis.With the development of x-ray facilities and optical devices,3D-XRF analysis with a micro confocal volume will create a great potential for 2D and 3D microstructural analysis and accurate quantitative analysis.However,the classic measurement method of scanning metal foils of a certain thickness leads to inaccuracy.A method for calibrating the confocal volume is proposed in this paper.The new method is based on the basic content of the textbook,and the theoretical results and the feasibility are given in detail for the 3D-XRF mono-chromatic x-ray condition and the poly-chromatic x-ray condition.We obtain a set of experimental confirmation using the poly-chromatic x-ray tube in the laboratory.It is proved that the sensitivity factor of the 3D-XRF can be directly and accurately obtained in a real calibration process.
基金Supported by the Natural Science Foundation of Henan Province (No. 0611023700)Natural Science Foundation of Education Department of Henan Province (No. 2006150019)
文摘A new supramolecular compound, { [2-(2-pyridyl)benzimidazoleH2]2+.[SBC15]2-}2, was synthesized by the hydrothermal reaction of o-diaminobenzene, 2-pyridinecarboxylie acid and SbCl3 in 1:1 HC1 solution, and characterized by chemical analysis, elemental analysis, IR spectra, thermogravimetfic analysis and fluorescence spectra. The crystal structure was deter- mined by X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P211c, with a = 16.0397(13), b = 14.3189(12), c = 15.6370(13) A, β = 105.8980(10)°, V = 3454.0(5) A3, Z = 4, C24H22Cl10N6Sb2, Mr = 992.48, Dc = 1.909 g/cm3,/z = 2.366 mm-1, S = 1.010, F(000) = 1920, R = 0.0254 and wR = 0.0555. The coordination anion, [SbCl5]2- which is a distorted tetragonal pyramid, is composed by coordinating action with Sb3+ ion and five adjacent chloride ions. Every four coordination anions of [SbCl5]2- form a biquaternion ring structure through the secondary bonding of Sb...Cl. Moreover, the compound adopts a three-dimensional network supramolecular structure because of the hydrogen bonds and π-π stacking between the rings and the 2-(2-pyridyl)benzimidazole divalent cations. The title compound also shows good fluorescent behaviors.
文摘Tryptophan(Trp) residues in a pullulanase were modified by N-bromosuccinimide(NBS). The results of the Spande method indicate that there are 18 Trp residues in the pullulanase and nine of them are located on the surface af the enzyme. Three of these Trp residues are nonessential residues which show the fastest reaction rate according to the Zou's plot. Two of the seven relative faster reacting residues are essential for the activity of the enzyme. The other eight are the slowest in the reaction rate or non-reactive residues for the reaction. The fluorescence and circular dichroism(CD) spectra of the pullulanase have been changed after the reaction with NBS. Potassium iodide(KI) and acrylamide also have remarkable influences on the fluorescence spectra of the pullulanase.
文摘The steady-state fluorescence spectrum characteristic of ethanol-water excimer has been studied in this paper. By analysing the features of the sharp emission spectrum with fine structures in a shortwave band and the characteristics of the broad and featureless fluorescence peaks in the longwave band, one can conclude that the excimers are formed between the new ethanol-water cluster molecules in the excited state and the ground state through the interaction among different chromophores. The excitation spectra in the two fluorescence bands have been studied, and their emission mechanisms have been ascertained based on the energy transfer theory. Furthermore, the critical distance of the resonance energy transfer has been calculated.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304203 and 2016YFF0200104)the National Natural Science Foundation of China(Grant Nos.61505099,61827824,91536110,and 61975104)the Fund for Shanxi ‘1331 Project’ Key Subjects Construction,Bairen Project of Shanxi Province,China
文摘Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modulated.The experiment results show that the signal to noise ratio has been improved by 32.64 dB when the modulation depth(converted to laser frequency)and frequency are optimized to 4 MHz and 6 kHz,respectively.This technique enables us to perform a highly sensitive non-destructive detection of Rydberg atoms.
基金supported by the National Key R&D Project of China(No.2017YFC0602100)the National Natural Science Foundation of China(No.41774147)Sichuan Science and Technology Support Program(No.2015GZ0272)
文摘The full-spectrum least-squares(FSLS) method is introduced to perform quantitative energy-dispersive X-ray fluorescence analysis for unknown solid samples.Based on the conventional least-squares principle, this spectrum evaluation method is able to obtain the background-corrected and interference-free net peaks, which is significant for quantization analyses. A variety of analytical parameters and functions to describe the features of the fluorescence spectra of pure elements are used and established, such as the mass absorption coefficient, the Gi factor, and fundamental fluorescence formulas. The FSLS iterative program was compiled in the C language. The content of each component should reach the convergence criterion at the end of the calculations. After a basic theory analysis and experimental preparation, 13 national standard soil samples were detected using a spectrometer to test the feasibility of using the algorithm. The results show that the calculated contents of Ti, Fe, Ni, Cu, and Zn have the same changing tendency as the corresponding standard content in the 13 reference samples. Accuracies of 0.35% and 14.03% are obtained, respectively, for Fe and Ti, whose standard concentrations are 8.82% and 0.578%, respectively. However, the calculated results of trace elements (only tens of lg/g) deviate from the standard values. This may be because of measurement accuracy and mutual effects between the elements.
文摘The amino acid composition of the superoxide dismutase(SOD) from camellia pollen was measured and the tryptophan(Trp) residues were modified by using N-bromosuccinimide(NBS). The results show that there are 21 Trp residues in an SOD molecule and seven of which are located on the surface of the enzyme. By researching the fluorescence spectra of the native SOD and the modified SOD, we have found that the emission wavelength of Trp is at 335 nm and the fluorescence intensity will decrease when the enzyme is modified. The results also show that potassium iodide(KI) can significantly quench the fluorescence of the native SOD, but it has a less pronounced effect on the modified enzyme. Glycerin as a surface activation reagent can stabilize the fluorescence of the modified enzyme.
文摘Tryptophan residues in hyaluronidase (HAase) were modified by N-bromosuccinimide (NBS), the results indicated that there were eleven tryptophan residues in HAase, one of which was exposed and essential for the activity of the enzyme. The study on fluorescence quenching showed that KI could not quench all of the fluorescence from Trp residues in HAase, while acrylamide (Acr) could quench almost all of the fluorescence from Trp residues in HAase. The collisional quenching constants (KD) of HAase at different concentrations of Acr were calculated in terms of Stern-Volmer equation. The results implied that some of the Trp residues were buried in the interior of HAase and the Trp residue on the surface of HAase was not located in the hydrophobic pocket.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (No.20673107), the National Key Basic Research Special Foundation of China (No.G2007CB815203), and the Chinese Academy of Sciences (No.KJCX2-YW-N24).
基金This work was supported by grantsfromThe Int .Cooperation Projectfor National &Abroad Lab.of the National Natural Sciences Foundation ofChina(2002008) and The Science &Technology Foundation of Liaoningprovince (20022140)
文摘The suppression of diorganogermanium compounds on the Maillard reaction of histidine(His) and glycine (Gly) with glucose has been determined by fluorescence spectrum underphysiological conditions. The title compounds show inhibition for the fluorescence intensity (FI) ofglycosylated andno acids stronger than Ge-132.
基金Supported by Key research project of hainan province,a pilot trial on the development of the health-care and anti-inflammatory products of Clinacanthus nutans ferment,S100007043008。
文摘Objective:To set up a database of three-dimensional fluorescence spectra of traditional Chinese medicines,Screening of medicinal materials by three-dimensional fluorescence spectroscopy,Methods:The paper Summarizes the three-dimensional fluorescence fingerprints,screens medicinal materials on basis of verifying the three-dimensional fluorescence spectra of the reference crude herbs of the national standard Chinese medicines,and combines with visual basic6.0 and microsoft access 2003 technology system to construct a three-dimensional fluorescence fingerprint database of TCMs.Results:the identification and quality control of traditional Chinese medicines(TCMs)was accuately and swiftly achieved.Conclusion:The relevant analysis on the operating system of database and the three-dimensional fluorescence spectrum database of TCMs indicates that this operating system can provide convenient channels for the inspection,verification and quality control of TCMs.
文摘Phenylcarboxymethyl Sulfoxide, PhSOCH 2COOH(LH), complexes of six lanthanide nitrates: Ln 2L 2(NO 3) 4·2LH· n H 2O(where Ln=La, Ce, Pr, Nd, Sm, Eu) were synthesized. Elemental analyses, molar conductivities, IR, 1HNMR and TG DTA measurements were used to characterize the complexes. The results show that the ligand(L) is coordinated to metal ions through two oxygen atoms of the carboxyl group and one oxygen atom of the sulfoxide moieties. Neutral ligang (LH)is coordinated to two metal ions through two oxygen atoms of carboxyl group as an asymmetrical bridging bidentate. The fluorescence spectra of Eu 3+ complex indicates that there is no inversion symmetry at the site of Eu 3+ ion, but the emission intensity of fluorescence is quite good.The solubility of the complexes is very good in water.
基金The National Natural Science Foundation of China under contract No.40706036the National High-Tech Research and Development Program of China ("863" Program) under contract No.2006AA09Z178
文摘The excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate phytoplankton populations at phylum level in vivo and in situ within a few minutes.The investigated phytoplankton divisions (Dinophyta,Bacillariophyta,Chrysophyta,Cyanophyta,Cryptophyta,Chlorophyta) are each characterized by a specific composition of photosynthetic antenna pigments and,consequently,by a specific excitation spectrum of the Chl fluorescence.Norm excitation spectra (emission of 680 nm and excitation of 400–600 nm) of every division were obtained from several species per division by a F4500 fluorescence spectrophotometer.Fisher’s linear discriminant analysis of the norm spectra shows that the divisions could be discriminated.The discrimination method,established by multivariate linear regression and weighted least squares,was used to differentiate the phytoplankton samples cultured in the laboratory and samples collected from the Jiaozhao Bay at division level.The correctly discriminated samples were more than 94% for single algal species ones,more than 84% for simulatively mixed ones,more than 83% for real mixed ones and 100% for samples collected from the Jiaozhou Bay for the dominant species.The method for phytoplankton differentiation described here can be applied to routine checking by fluorescence spectrophotometer,and benefit the monitoring and supervision tasks related to phytoplankton populations in the marine environments.
基金supported by the Education Department of Zhejiang Province (20050359)
文摘A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3+-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3+. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3+-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.
基金supported by the National High Technology Research and Development Program (2006AA06Z415)the Global Change Research Program of China (2012CB955603)
文摘A Multi-channel Oceanographic Fluorescence Lidar(MOFL), with a UV excitation at 355 nm and multiple receiving channels at typical wavelengths of fluorescence from oil spills and chlorophyll-a(Chl-a), has been developed using the Laser- induced Fluorescence(LIF) technique. The sketch of the MOFL system equipped with a compact multi-channel photomultiplier tube(MPMT) is introduced in the paper. The methods of differentiating the oil fluorescence from the background water fluorescence and evaluating the Chl-a concentration are described. Two field experiments were carried out to investigate the field performance of the system, i.e., an experiment in coastal areas for oil pollution detection and an experiment over the Yellow Sea for Chl-a monitoring. In the coastal experiment, several oil samples and other fluorescence substances were used to analyze the fluorescence spectral characteristics for oil identification, and to estimate the thickness of oil films at the water surface. The experiment shows that both the spectral shape of fluorescence induced from surface water and the intensity ratio of two channels(I495/I405) are essential to determine oil-spill occurrence. In the airborne experiment, MOFL was applied to measure relative Chl-a concentrations in the upper layer of the ocean. A comparison of relative Chl-a concentration measurements by MOFL and the Moderate Resolution Imaging Spectroradiometer(MODIS) indicates that the two datasets are in good agreement. The results show that the MOFL system is capable of monitoring oil spills and Chl-a in the upper layer of ocean water.
基金supported by the National Natural Science Foundation of China (No. 41476081)the Major Research and Development Project in Shandong Province (Nos. 2016GSF115020, 2019GHY112027)the Shandong Provincial Natural Science Foundation (No. ZR2015DM007)
文摘Sensitivity is crucially important for surface-enhanced Raman spectroscopy(SERS)application to detect trace-level polycyclic aromatic hydrocarbons(PAHs)in the seawater.In this study,a high sensitivity three-dimensional(3-D)SERS substrate composed with syringe filter,glycidyl methacrylate-ethylene dimethacrylate(GMA-EDMA)porous material and optimal parameters(57 nm,pH 13)gold nanoparticles(Au NPs)was developed for the detection of PAHs in water.The enhancement effect and repeatability of this 3-D substrate were also explored.The Raman intensity of pyrene using 3-D SERS substrate is about 8 times higher than that of substrate only using p H 13 gold colloid solution and about 12 times higher than that of substrate using natural Au NPs and GMA-EDMA porous material,which means both the pH 13 AuN Ps and the GMA-EDMA porous material are important factors for the sensitivity of this 3-D SERS substrate.Good repeatability of this optimal 3-D substrate was obtained.The relative standard deviation(RSD)is less than 8.66% on the same substrate and less than 3.69% on other different substrates.Four kinds of PAHs,i.e.,phenanthrene,pyrene,benzo(a)pyrene,benzo(k)fluoranthene and their mixture,were detected at the different concentrations.Their limits of detection(LODs)are 8.3×10^-10(phenanthrene),2.1×10^-10(pyrene),3.8×10^-10(benzo(a)pyrene)and 1.7×10^-10 mol L^-1(benzo(k)fluoranthene),respectively.In addition,these four PAHs were also detected by fluorescence spectroscopy to evaluate the sensitivity of SERS technology using this optimal 3-D SERS substrate.The results showed that the sensitivity of SERS based on the 3-D SERS substrate even using the portable Raman system was closed to that of fluorescence spectroscopy.Therefore,the SERS technology using this optimal 3-D substrate is expected to be an in-situ method for the detection of environmental PAHs.
基金supported by a grant from the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Fluoro-ruby was injected into the posterior funiculus of the spinal cord in the cervical (C5-T2) and lumbar (L3-6) segments of adult guinea pigs. The spinal cord was cut into serial frozen sections. The Fluoro-ruby labeling was clearly delineated from the surrounding structure. The labeling traversed the cervical, thoracic and lumbar segments, and was located on the ventral portion of the posterior funiculus on the injected side, proximal to the intermediate zone of the dorsal gray matter. The fluorescence area narrowed rostro-caudally. The spinal cord, spinal cord gray matter and corticospinal tract were reconstructed using 3D-DOCTOR 4.0 software, resulting in a robust three-dimensional profile. Using functionality provided by the reconstruction software, free multi-angle observation and sectioning could be conducted on the spinal cord and corticospinal tract. Our experimental findings indicate that the Fluoro-ruby retrograde fluorescent tracing technique can accurately display the anatomical location of corticospinal tract in the guinea pig and that three-dimensional reconstruction software can be used to provide a three-dimensional image of the corticospinal tract.