A direct recording corrected microspectrofluorometer

The construction of a microspectrofluorometer with automatic correction capabilities is given. The instrument uses a quantum counting system for correction of excitation spectra and an interpolating function generator for correction of emission spectra. An inexpensive analogue computer is an integral part of the electronic portion of the instrument and allows a number of mathematical manipulations to be performed on the sample and reference signals prior to recording or display. Under the conditions stated, the sensitivity of the instrument is in the 10^?9 M range for quinine sulphate irradiated at 365 nm. The linear response range for quinine sulphate is 10^?3 to 10^?9 M. The operational wavelength range of the machine is between 226 and 700 nm.     

Mesoscopic structures and dynamics of merocyanine J-aggregate studied by time-resolved fluorescence SNOM

Time-resolved fluorescence SNOM is used to probe the mesoscopic structure and dynamics of long-chain merocyanine (C₁₈MC) J-aggregates on glass plates prepared by spin coating, casting, and casting of water-soluble polymer films. A globular structure with an average diameter of ∼ 1 µm and a height of ∼ 50 nm was attributed to the J-aggregate of C₁₈MC in the spin-coating film. In polymer films, the bandwidth of the absorption of J-aggregate is much narrower in polyvinyl alcohol (PVA, ∼ 20 nm) than that in polyvinyl sulphate (PVS, ∼ 60 nm). We have demonstrated that the large bandwidth of the spectrum is due to the inhomogeneous distribution of the J-aggregate. The fluorescence image of the J-aggregate in PVA film was rather uniform, whereas non-uniform distribution of the fluorescence was observed in PVS film. The fluorescence of C₁₈MC J-aggregate in a small domain of PVA film was a single exponential decay with a lifetime as short as 19 ps, which was shorter than that in PVS film with a two-exponential decay (average lifetime of ∼ 25 ps). The fluorescence lifetime of the J-aggregate and its single exponential behaviour are considered to be indicators of the uniform distribution of the J-aggregate. The non-uniform distribution of the J-aggregate in PVS film was interpreted in terms of electrostatic interaction between PVS and merocyanine.     

多功能灵敏固相时间分辨荧光免疫分析仪设计

针对固相时间分辨荧光光谱的测量,设计出一种全新的固相时间分辨荧光免疫分析系统.使用氮分子激光器作为激发光源,采用积分球和单色仪相结合的荧光收集结构,使杂散光对样品荧光的影响降到最低;用光电倍增管进行光电转换,在500～700 nm范围实现了高分辨荧光光谱测量;利用数字方式实现取样积分功能,提高了系统的信噪比.系统可实现荧光寿命、时间分辨荧光光谱、物质浓度的自动测量,仪器的检测灵敏度可达10 - 12 moL/L,线性范围为10-12～10-9 mol/L,稳定性相对误差小于3％,荧光光谱分辨为0.5nm.     

时间分辨荧光光纤生物传感器的研制及应用

首次研制了一种完全利用光纤实现光耦合及传输的时间分辨荧光光纤生物传感器.该传感器以镧系离子(铕离子)作为被检测物质的荧光标记物,根据铕离子的荧光特性,利用时间分辨检测技术进行生物医学检测.光学部分采用光纤耦合器和石英光纤作生物样品激发光的传导光学元件,生物样品受激发产生的荧光也同样由光纤耦合器及光纤收集和传导,实现了该传感器的紧凑性和小型化,提高了检测灵敏度.经性能测试,该仪器不稳定性小于2.3%,重复测量的互相关高达99.9%.测铕离子标准液的检测限为7.3×10^-10g/L,达到国外有关文献报道的水平.     

Phase-locked 10 MHz reference signal for frequency domain time-resolved fluorescence measurements

A complete electronic system that is suitable for use in megahertz frequency domain time-resolved fluorescence instruments based on mode-locked lasers is described. The circuit produces a 10 MHz signal, phase locked to the mode-locked laser pulse frequency, which is required by many commercial frequency synthesizers as the external reference signal. This device is particularly useful in conjunction with ultrafast gated intensified charge coupled device cameras capable of being frequency modulated for time-resolved fluorescence imaging.     

基于PCA的时间分辨油荧光光谱分析及优化

激光诱导荧光技术可广泛应用于油污染的监测中,然而普通的油荧光光谱技术只能实现油污染监测的粗分类,无法区分原油与燃料油的荧光特征。本文基于主成分分析方法(PCA)的时间分辨油荧光分类方法,实验测量了20种油样本的时间分辨荧光光谱特征,给出了对应的荧光寿命和时间分辨油荧光光谱的时序特征。在此基础上,利用前三个主成分构成的三维特征矢量空间,通过分析不同采集时刻下油样本矢量间相关距离的变化,对油样本的时间分辨荧光光谱进行聚类分析。为了体现油荧光变化的时序性,引入矢量距离的离散度参量,提出基于PCA进行时间分辨油荧光光谱分析的优化方法。实验结果表明,基于时间分辨油荧光光谱识别可实现原油与燃料油的光谱时序特征区分,具备良好的油荧光分类效果。     

Measurement of nanosecond time-resolved fluorescence with a directly gated interline CCD camera

CCD cameras coupled optically to gated image intensifiers have been used for fast time‐resolved measurements for some years. Image intensifiers have disadvantages, however, and for some applications it would be better if the image sensor could be gated directly at high speed. Control of the ‘charge drain’ function on an interline‐transfer CCD allows the sensor to be switched rapidly from an insensitive state. The temporal and spatial properties of the charge drain are explored in the present paper and it is shown that nanosecond time resolution with acceptable spatial uniformity can be achieved for a small commercial sensor. A fluorescence lifetime imaging system is demonstrated, based on a repetitively pulsed laser excitation source synchronized to the CCD control circuitry via a programmable delay unit.     

Picosecond time-resolved microspectrofluorometry in live cells exemplified by complex fluorescence dynamics of popular probes ethidium and cyan fluorescent protein

Time‐resolved microspectrofluorometry in live cells, based on time‐ and space‐correlated single‐photon counting, is a novel method to acquire spectrally resolved fluorescence decays, simultaneously in 256 wavelength channels. The system is calibrated with a full width at half maximum (FWHM) of 90 ps for the temporal resolution, a signal‐to‐noise ratio of 10⁶, and a spectral resolution of 30 (Δλ/Λ). As an exemple, complex fluorescence dynamics of ethidium and cyan fluorescent protein (CFP) in live cells are presented. Free and DNA intercalated forms of ethidium are simultaneously distinguishable by their relative lifetime (1.7 ns and 21.6 ns) and intensity spectra (shift of 7 nm). By analysing the complicated spectrally resolved fluorescence decay of CFP, we propose a fluorescence kinetics model for its excitation/desexcitation process. Such detailed studies under the microscope and in live cells are very promising for fluorescence signal quantification.     

Scanning-less wide-field single-photon counting device for fluorescence intensity, lifetime and time-resolved anisotropy imaging microscopy

A scanning‐less single‐photon counting system for FLIM and fluorescence anisotropy wide‐field imaging is described and characterized in this paper. The two polarizations of the fluorescence are divided by a Glan prism and acquired at the same time by the Q_A detector. Fluorescence decay profiles can be reconstructed for any desired area up to each pixel and used to calculate time‐resolved fluorescence anisotropy decays.     

A semiconductor electron current detector for the direct recording of electron microscopic diffraction images

A semiconductor detector for the direct time-serial recording of electron microscopic diffraction images is presented. The recording method is described and the performance of the detector compared to that of a standard STEM scintillator/photomultiplier chain.     

激光诱导纳秒时间分辨荧光技术原位检测环境中多环芳烃的应用及展望

介绍激光诱导纳秒时间分辨荧光技术的发展、现状。相比其他检测环境中多环芳烃的方法、手段,结合激光诱导纳秒时间分辨荧光技术在实际工作中的应用,评述其在检测实际环境中多环芳烃方面的应用优势、潜力及前景展望。     

Direct modulation of the effective sensitivity of a CCD detector: a new approach to time-resolved fluorescence imaging

In this paper a novel approach to frequency‐domain fluorescence lifetime imaging (FLIM) is described. In a CCD camera a single pixel is defined by a charge pattern on a group of electrodes. By modulation of the pattern of voltages defining the pixel structure it is possible to modulate the sensitivity of the CCD at radio frequency. The modulation enhances the noise performance of the CCD, in contrast to the deterioration in performance seen when an intensifier stage is similarly modulated. The new technology has potential applications to a wide range of assays as well as in conventional FLIM applications. Unlike intensifier‐based systems, the directly modulated CCD is physically small, inexpensive, robust and offers superior resolution and noise performance.     

A setup for remote recording of the spectrum of laser-induced fluorescence from crowns of woody plants

A setup intended for remote studies of the chlorophyll content in woody plants is described. Fluorescence spectra from an object under study excited by laser radiation at a wavelength of 532 nm are recorded in the spectral range 600–850 nm. The performance characteristics of the setup allow acquisition of the spectra of short-term fluorescence of nanosecond duration, which are normalized to the maximum value of the signal of the reference channel. An MДP-23 monochromator is used as an element of spectral selection. Examples of recording a return pulse and the fluorescence spectrum from a Scotch pine are presented.     

In situ 3D measurement of lubrication behavior at interface between tool and workpiece by direct fluorescence observation technique

A new direct observation method, which is based on an optical microscopy and a conventional fluorescence method, is developed in order to measure the oil film thickness at the interface between the tool and the workpiece in lubricated upsetting. The oil film thickness is measured using this method. The oil film thickness and the distribution at the interface during lubricated upsetting can be measured three dimensionally. The calculated central thicknesses at the instant of entrapment are in good agreement with the measured ones for lubricants with higher viscosity at higher compression speed. The 3D surface topography of workpiece at the end surface can be clearly visualized.     

Study of energy transfer from excited TPD to Alq in organic electroluminescent devices by time-resolved fluorescence spectroscopy using a scanning near-field optical atomic force microscope

We demonstrate the direct measurement of molecular diffusion at organic/organic interfaces of organic electroluminescence devices by use of a scanning near-field optical atomic force microscope. Our preliminary study shows that the degradation of an electroluminescence device is partly caused by crystallization of the organic layers. Because the initial stage of degradation cannot be observed by microscopic methods, nanoscale optical properties of the interface in multilayer systems are currently receiving a great deal of attention. Defects of organic electroluminescence devices were investigated using a scanning near-field optical atomic force microscope. This instrument is capable of measuring both a topographic and a fluorescence image at the same time. The defect area and other areas are clearly observed and time-resolved near-field fluorescence spectra demonstrate emission of the different species. These results suggest that defects occur at the organic solid interface, and that energy transfer occurs from excited TPD, as donor, to Alq, as acceptor.     

A thermal study of cellular motility by optical time-resolved correlation

The study of motor properties of cells under appropriate physical-chemical conditions is a significant problem nowadays. The standard techniques presently used do not allow to evaluate neither large samples nor to control their thermodynamic conditions. In this work, we report a cell motility sensor based on an optical technique with a time-resolved correlation, adapted in a system able to study several samples simultaneously. Image correlation analysis is used to follow their temporal behavior. A wide variety of motile cells, such as archaea, bacteria, spermatozoa, and even contractile cells, can be studied using this technique. Here, we tested our technique with the study of sperm motility. In particular, both the sperm motility and its prevalence are studied under a temperature range from 0 to 37 °C. We found that incubation at 10 °C presents the lengthiest prevalence in motility and observed, for the first time, an interesting thermal reversibility behavior.     

Use of a night vision intensifier for direct visualization by eye of far-red and near-infrared fluorescence through an optical microscope

We describe the design, construction and testing of a prototype device that allows the direct visualization by eye of far‐red and near‐infrared (NIR) fluorescence through an optical microscope. The device incorporates a gallium arsenide (GaAs) image intensifier, typically utilized in low‐light or ‘night vision’ applications. The intensifier converts far‐red and NIR light into electrons and then into green light, which is visible to the human eye. The prototype makes possible the direct, real‐time viewing by eye of normally invisible far‐red and NIR fluorescence from a wide variety of fluorophores, using the full field of view of the microscope to which it is applied. The high sensitivity of the image intensifier facilitates the viewing of a wide variety of photosensitive specimens, including live cells and embryos, at vastly reduced illumination levels in both fluorescence and bright‐field microscopy. Modifications to the microscope are not required in order to use the prototype, which is fully compatible with all current fluorescence techniques. Refined versions of the prototype device will have broad research and clinical applications.     

[学科发展]深冷轧制制备高性能金属材料研究进展

相对于传统热轧、温轧、冷轧,深冷轧制是一项变革性技术,它利用某些金属材料在深冷情况下具有优异的塑性变形能力以及深冷环境阻碍塑性变形过程中位错运动和再结晶行为,促使材料晶粒细化,材料具有更高的强度与韧性。系统地介绍了近年来深冷轧制制备高性能金属材料的研究进展,包括深冷轧制在铝合金、铜合金、钛合金、复合层状金属带材中的应用。对深冷轧制制备高性能金属材料的研究进行了展望。     

液相色谱-质谱联用法鉴定必特螺旋霉素中多组分

采用 Kromasil C18色谱柱 ( 5μm粒径 ,2 0 0× 4.6mm内径 ) ,流动相为乙腈 -1 0 mmol/ L乙酸铵溶液 ( V(乙腈 )∶V(乙酸铵 ) =60∶ 45 ) ,建立快速分析抗生素新药必特螺旋霉素中复杂多组分的分析方法。采用电喷雾离子化源 ,以正离子检测方式进行一级、二级全扫描质谱分析。研究表明 :其中含有 1 0种螺旋霉素类衍生物并推断出化学结构 ,通过与对照品的色谱和质谱行为对比得到验证。采用液相色谱 -质谱联用技术 ( LC-MSn)可以快速阐明复杂多组分抗生素新药必特螺旋霉素类的化学组成 ,并且可以作为一种简单、便捷的分析方法对大环内酯类新抗生素进行高通量筛选。     

电场驱动喷射微3D打印的高性能纸基电路制造工艺研究

提出了一种基于电场驱动喷射沉积微尺度3D打印制造高分辨率纸基电子的新方法。阐述了该方法的基本原理与工艺流程,通过实验揭示了主要工艺参数（电压、气压、打印速度）对三种纸质基材上打印银线的质量和精度影响及其规律。利用自主研发的电场驱动喷射微3D打印机,使用含银量75%和动力黏度35 Pa·s（25 ℃）的低温纳米银浆,并结合优化工艺窗口,在纸质基材上通过多层堆叠打印实现了高分辨率、大高宽比微纳结构,其中在RC相纸上堆积15层后,其线宽可保持在10 μm、高宽比增至6.33,电阻下降了94.8%。最后,在不同纸质基材表面制作了柔性电磁驱动器、复杂导电图案等样件来证明其打印能力。结果表明,采用电场驱动射流沉积微尺度3D打印技术新方法,并结合高黏度低温烧结纳米银浆,可为高性能纸基电子制造提供有效途径。