A new,simple,rapid microbial assay was put forward for the detection of chloramphenicol(CAP)residues in Turbot muscles using luminescent bacteria DB(Photobacterium phosphoreum)as test organ-ism.By the luminescence inh...A new,simple,rapid microbial assay was put forward for the detection of chloramphenicol(CAP)residues in Turbot muscles using luminescent bacteria DB(Photobacterium phosphoreum)as test organ-ism.By the luminescence inhibition of DB,the concentrations of CAP were determined.CAP spiked inTurbot muscle tissues ranging from 0.5 to 100μg/kg was extracted using ethyl acetate and hexane.Themethod had a good recovery of 93.69% with a minimum detection limit of 0.65μg/kg.It can be per-formed within 30min following simple extraction.The method therefore proved to be advantageous overchromatographic procedures as it was inexpensive,quite sensitive and can be adopted for rapid screeningof CAP in Turbot tissues.展开更多
Micro-structures 3-D profile measurement is an important measurement content for research on micro-machining and characterization of micro-dimension. In this paper,a new method involved 2-D structure template, which g...Micro-structures 3-D profile measurement is an important measurement content for research on micro-machining and characterization of micro-dimension. In this paper,a new method involved 2-D structure template, which guides phase unwrapping,is proposed based on phase-shifting microscopic interferometry.It is fit not only for static measurement, but also for dynamic measurement,especially for motion of MEMS devices.3-D profile of active comb of micro-resonator is obtained by using the method.The theoretic precision in out-of-plane direction is better than 0.5 nm.The in-plane theoretic precision in micro-structures is better than 0.5 μm.But at the edge of micro-structures,it is on the level of micrometer mainly caused by imprecise edge analysis.Finally,its disadvantages and the following development are discussed.展开更多
When the organic vapors absorbed to the surface of porous silicon(PS), capillary condensation takes place due to the porous structure of the PS layer, accordingly resulting in the effective refractive index changing. ...When the organic vapors absorbed to the surface of porous silicon(PS), capillary condensation takes place due to the porous structure of the PS layer, accordingly resulting in the effective refractive index changing. For PS multi-layer microcavities, the different resonant peaks shift in the reflectivity spectrum of porous silicon microcavities(PSMs). The optical sensing model is set up by applying Bruggeman effective medium approximation theory, capillary condensation process and transfer matrix theoretically analytical method of one-dimensional photonic crystals. At the same time, comprehensively researched on are the sensing characteristics of PSMs which are exposed to give concentration organic vapors. At last, made is the theoretical simulation for sensing model of the PSMs in case of saturation by using computer numerical calculation, and found is the linearity relation between the refractive index of organic solvent and the peak-shift. At the same time deduced is the peak-shift as a function of the concentration of ethanol vapors.展开更多
When interference microscope measures the surface rough of the micromechanical device, as soon as the work distance of interference microscope and the depth of field is shortened, the interference images become slur f...When interference microscope measures the surface rough of the micromechanical device, as soon as the work distance of interference microscope and the depth of field is shortened, the interference images become slur for the measured object if there has small interference after clear focus. The auto-focusing system is introduced into the interference microscope, the system can obtain high definition interference image rapidly,and can improve the measuring velocity and measuring precision. The system is characterized by auto-focusing range of ±150 μm, auto-focusing precision of ±0.3 μm, auto-focusing time of 4～8 s.展开更多
A single cesium atom is trapped in a far-off-resonance optical dipole trap （FORT） from the magneto-optical trap （MOT） and directly imaged by using a charge-coupled device （CCD） camera. The binary single-atom ste...A single cesium atom is trapped in a far-off-resonance optical dipole trap （FORT） from the magneto-optical trap （MOT） and directly imaged by using a charge-coupled device （CCD） camera. The binary single-atom steps and photon anti-bunching are observed by a photon-counting-based HBT system using fluorescence light. The average atom dwelling time in the FORT is about 9 s. To reduce the background noise in the detection procedure we employ a weak probe laser tuned to the D1 line to il- lurninate the single atom from the direction perpendicular to the large-numerical-aperture collimation system. The second or- der degree of coherence g（2）（r）=0.12_＋0.02 is obtained directly from the fluorescence light of the single atom without deducting the background. The background light has been suppressed to 10 counts per 50 ms, which is much lower compared with the reported results. The measured g（2）（r） is in good agreement with theoretical analysis. The system provides a simple and effi- cient method to manipulate and measure single neutral atoms, and opens a way to create an efficient controlled single-photon source.展开更多
Chemiluminescence detection was developed as an alternative to amperometric detection for glucose analysis in a portable, microfluidicsbased continuous glucose monitoring system. Amperometric detection allows easy det...Chemiluminescence detection was developed as an alternative to amperometric detection for glucose analysis in a portable, microfluidicsbased continuous glucose monitoring system. Amperometric detection allows easy determination of hydrogen peroxide, a product of the glucose oxidasecatalyzed reaction of glucose with oxygen, by oxidation at a microelectrode. However, （micro）electrodes in direct contact with physiological sample are subject to electrode fouling, which leads to signal drift, decreased reproducibility and shortened detector lifetimes. Moreover, there are a few species present in the body （e.g. ascorbic acid, uric acid） which can undergo oxidation at the same applied potential as hydrogen peroxide. These species can thus inter- fere with the glucose measurement, reducing detection specificity. The rationale for exploring chemiluminescence as opposed to amperometric detection is thus to attempt to improve the lifetime and reproducibility of glucose analysis for monitoring purposes, while reducing interference caused by other chemicals in the body. The study reported here represents a first step in this direction, namely the realization of a microfluidic device with integrated silicon photodiode for chemiluminescence detection of glucose. This microflow device uses a chaotic mixing approach to perform enzymatic conversion of glucose, followed by reaction of the hydrogen peroxide produced with luminol to produce light at 425 nm. The chemil reaction is catalyzed by horseradish peroxidase in the presence of iodophenol. The performance of the fabricated chip was characterized to establish optimal reaction conditions with respect to sample and reagent flow rates, pH, and concentrations. A linear calibra- tion curve was obtained for current response as a function of glucose concentration in the clinically relevant range between 2 and 10 mM, with a sensitivity of 39 pA/mM （R = 0.9963, one device, n = 3） and a limit of detection of 230 ktM （S/N - 3）.展开更多
In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ...In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ultraweak luminescence detection system, and find the significant difference in the weight distributions of the decay rate for hUC-MSCs with high and low viabilities. Spectral discrimination of hUC-MSCs with high and low viabilities is thus carried out by comparing the DL kinetics parameters, including the initial intensity, the peak decay rate and the peak weight value. Our results show that the novel optical method for the viability diagnosis of hUC-MSCs has a promising prospect.展开更多
Ultralong phosphorescent materials have numerous applications across biological imaging, lightemitting devices, X-ray detection and anti-counterfeiting. Triplet-state molecular phosphorescence typically accompanies th...Ultralong phosphorescent materials have numerous applications across biological imaging, lightemitting devices, X-ray detection and anti-counterfeiting. Triplet-state molecular phosphorescence typically accompanies the singlet-state fluorescence during photoluminescence, and it is still difficult to achieve direct triplet photoemission as ultralong room temperature phosphorescence(RTP). Here, we have designed Zn-IMDC(IMDC, 4,5-imidazoledicarboxylic acid) and Cd-IMDC, two-dimensional(2D)hydrogen-bond organized metal–organic crystalline microsheets that exhibit rarely direct ultralong RTP upon UV excitation, benefiting from the appropriate heavy-atom effect and multiple triplet energy levels. The excitation-dependent and thermally stimulated ultralong phosphorescence endow the metal–organic systems great opportunities for information safety application and temperature-gated afterglow emission. The well-defined 2D microsheets present color-tunable and anisotropic optical waveguides under different excitation and temperature conditions, providing an effective way to obtain intelligent RTP-based photonic systems at the micro-and nano-scales.展开更多
Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled ...Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).展开更多
基金Supported by the National Natural Science Foundation of China ( No. 30500384)the High Technology Research and Development Programme of China (No. 2006AA09Z431)
文摘A new,simple,rapid microbial assay was put forward for the detection of chloramphenicol(CAP)residues in Turbot muscles using luminescent bacteria DB(Photobacterium phosphoreum)as test organ-ism.By the luminescence inhibition of DB,the concentrations of CAP were determined.CAP spiked inTurbot muscle tissues ranging from 0.5 to 100μg/kg was extracted using ethyl acetate and hexane.Themethod had a good recovery of 93.69% with a minimum detection limit of 0.65μg/kg.It can be per-formed within 30min following simple extraction.The method therefore proved to be advantageous overchromatographic procedures as it was inexpensive,quite sensitive and can be adopted for rapid screeningof CAP in Turbot tissues.
基金Supported:Tianjin Important Science and Technology Project(043185911) National High-Technology Research and De-velopment Project (863 project) in China (2004AA404042) .
文摘Micro-structures 3-D profile measurement is an important measurement content for research on micro-machining and characterization of micro-dimension. In this paper,a new method involved 2-D structure template, which guides phase unwrapping,is proposed based on phase-shifting microscopic interferometry.It is fit not only for static measurement, but also for dynamic measurement,especially for motion of MEMS devices.3-D profile of active comb of micro-resonator is obtained by using the method.The theoretic precision in out-of-plane direction is better than 0.5 nm.The in-plane theoretic precision in micro-structures is better than 0.5 μm.But at the edge of micro-structures,it is on the level of micrometer mainly caused by imprecise edge analysis.Finally,its disadvantages and the following development are discussed.
文摘When the organic vapors absorbed to the surface of porous silicon(PS), capillary condensation takes place due to the porous structure of the PS layer, accordingly resulting in the effective refractive index changing. For PS multi-layer microcavities, the different resonant peaks shift in the reflectivity spectrum of porous silicon microcavities(PSMs). The optical sensing model is set up by applying Bruggeman effective medium approximation theory, capillary condensation process and transfer matrix theoretically analytical method of one-dimensional photonic crystals. At the same time, comprehensively researched on are the sensing characteristics of PSMs which are exposed to give concentration organic vapors. At last, made is the theoretical simulation for sensing model of the PSMs in case of saturation by using computer numerical calculation, and found is the linearity relation between the refractive index of organic solvent and the peak-shift. At the same time deduced is the peak-shift as a function of the concentration of ethanol vapors.
文摘When interference microscope measures the surface rough of the micromechanical device, as soon as the work distance of interference microscope and the depth of field is shortened, the interference images become slur for the measured object if there has small interference after clear focus. The auto-focusing system is introduced into the interference microscope, the system can obtain high definition interference image rapidly,and can improve the measuring velocity and measuring precision. The system is characterized by auto-focusing range of ±150 μm, auto-focusing precision of ±0.3 μm, auto-focusing time of 4～8 s.
基金supported by the State Basic Key Research Program of China (Grant No. 2012CB921601)China National Funds for Distinguished Young Scientists (Grant No. 11125418)the National Natural Science Foundation of China (Grant Nos. 10974125,61121064 and60978017)
文摘A single cesium atom is trapped in a far-off-resonance optical dipole trap （FORT） from the magneto-optical trap （MOT） and directly imaged by using a charge-coupled device （CCD） camera. The binary single-atom steps and photon anti-bunching are observed by a photon-counting-based HBT system using fluorescence light. The average atom dwelling time in the FORT is about 9 s. To reduce the background noise in the detection procedure we employ a weak probe laser tuned to the D1 line to il- lurninate the single atom from the direction perpendicular to the large-numerical-aperture collimation system. The second or- der degree of coherence g（2）（r）=0.12_＋0.02 is obtained directly from the fluorescence light of the single atom without deducting the background. The background light has been suppressed to 10 counts per 50 ms, which is much lower compared with the reported results. The measured g（2）（r） is in good agreement with theoretical analysis. The system provides a simple and effi- cient method to manipulate and measure single neutral atoms, and opens a way to create an efficient controlled single-photon source.
文摘Chemiluminescence detection was developed as an alternative to amperometric detection for glucose analysis in a portable, microfluidicsbased continuous glucose monitoring system. Amperometric detection allows easy determination of hydrogen peroxide, a product of the glucose oxidasecatalyzed reaction of glucose with oxygen, by oxidation at a microelectrode. However, （micro）electrodes in direct contact with physiological sample are subject to electrode fouling, which leads to signal drift, decreased reproducibility and shortened detector lifetimes. Moreover, there are a few species present in the body （e.g. ascorbic acid, uric acid） which can undergo oxidation at the same applied potential as hydrogen peroxide. These species can thus inter- fere with the glucose measurement, reducing detection specificity. The rationale for exploring chemiluminescence as opposed to amperometric detection is thus to attempt to improve the lifetime and reproducibility of glucose analysis for monitoring purposes, while reducing interference caused by other chemicals in the body. The study reported here represents a first step in this direction, namely the realization of a microfluidic device with integrated silicon photodiode for chemiluminescence detection of glucose. This microflow device uses a chaotic mixing approach to perform enzymatic conversion of glucose, followed by reaction of the hydrogen peroxide produced with luminol to produce light at 425 nm. The chemil reaction is catalyzed by horseradish peroxidase in the presence of iodophenol. The performance of the fabricated chip was characterized to establish optimal reaction conditions with respect to sample and reagent flow rates, pH, and concentrations. A linear calibra- tion curve was obtained for current response as a function of glucose concentration in the clinically relevant range between 2 and 10 mM, with a sensitivity of 39 pA/mM （R = 0.9963, one device, n = 3） and a limit of detection of 230 ktM （S/N - 3）.
基金supported by the National Natural Science Foundation of China(Nos.60508004 and 60778043)the National High Technology Research and Development Program of China(No.2011AA030205)+1 种基金the Doctoral Fund of Ministry of Education of China(No.20110031110035)the Tianjin Municipal Science and Technology Commission(No.08ZCDFGX09400)
文摘In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ultraweak luminescence detection system, and find the significant difference in the weight distributions of the decay rate for hUC-MSCs with high and low viabilities. Spectral discrimination of hUC-MSCs with high and low viabilities is thus carried out by comparing the DL kinetics parameters, including the initial intensity, the peak decay rate and the peak weight value. Our results show that the novel optical method for the viability diagnosis of hUC-MSCs has a promising prospect.
基金supported by the Beijing Municipal Natural Science Foundation(JQ20003)the National Natural Science Foundation of China(21771021,21822501,and 22061130206)+3 种基金the Fok Ying-Tong Education Foundation(171008)the Measurements Fund of Beijing Normal Universitythe State Key Laboratory of Heavy Oil Processing。
文摘Ultralong phosphorescent materials have numerous applications across biological imaging, lightemitting devices, X-ray detection and anti-counterfeiting. Triplet-state molecular phosphorescence typically accompanies the singlet-state fluorescence during photoluminescence, and it is still difficult to achieve direct triplet photoemission as ultralong room temperature phosphorescence(RTP). Here, we have designed Zn-IMDC(IMDC, 4,5-imidazoledicarboxylic acid) and Cd-IMDC, two-dimensional(2D)hydrogen-bond organized metal–organic crystalline microsheets that exhibit rarely direct ultralong RTP upon UV excitation, benefiting from the appropriate heavy-atom effect and multiple triplet energy levels. The excitation-dependent and thermally stimulated ultralong phosphorescence endow the metal–organic systems great opportunities for information safety application and temperature-gated afterglow emission. The well-defined 2D microsheets present color-tunable and anisotropic optical waveguides under different excitation and temperature conditions, providing an effective way to obtain intelligent RTP-based photonic systems at the micro-and nano-scales.
基金support under the National Basic Research Program of China (2009CB421605)National Key Water Program(2009ZX07207-002-03)National Natural Science Foundation of China (20977096)
文摘Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).
