[Intensity loss of two-photon excitation fluorescence microscopy images of mouse oocyte chromosomes].

As an optical microscope with high resolution, two-photon excitation (TPE) fluorescence microscope is widely used in noninvasive 3D optical imaging of biological samples. Compared with confocal laser scanning microscope, TPE fluorescence microscope provides a deeper detecting depth. In spite of that, the image quality of sample always declines as the detecting depth increases when a noninvasive 3D optical imaging of thicker samples is performed.

A quantification model for apoptosis in mouse embryos in the early stage of fetation.

Apoptosis is the most important inducement and modulator for embryos in the early stage of fetation, i.e. after the 8-cell stage, mostly the morula and blastula stage, to proceed to the stage of nonlinear development.

[Improved data processing method of fluorescence correlation spectroscopy].

By the unique ability of measuring concentration and diffusion coefficient, fluorescence correlation spectroscopy (FCS) has kept enlarging and deepening its application fields which need measuring physicochemical properties in complex mixtures. However, the classical data processing method in FCS generally induces errors in the fitting parameters, and the intuitionistic information in the chart is little or confused. Aiming at the above problems, we tried a new data processing method with differential treatment to find out whether it has multi-fluorescent-components and estimate the parameters intuitionally in the chart.

Capillary electrophoresis and circular dichroism study of trichosanthin and its mutants.

The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad spectrum of biological and pharmacological activities, including abortifacient, anti-tumor and anti-human-immunodeficiency-virus (anti-HIV). In this study, circular dichroism (CD) and capillary electrophoresis were used for the first time to study TCS and its two TCS mutants of Y55G TCS (tyrosine 55 converted to glycine) and FYY140-142GSA TCS (tripeptide phenylalanine-tyrosine-tyrosine 140-142 converted to glycine-serine-alanine). The results indicated that the substitution of amino acids changed the secondary structures and the hydrophobility of TCS.

[Application of two-photon excitation fluorescence imaging to real-time investigation of mouse preimplantation embryo].

The blue shift of a two-photon excitation absorption peak allows the application of a single wavelength to the simultaneous excitation of several fluorochromes with disparate emission characteristics. An output at 730 nm of a mode-locked femtosecond Ti-sapphire laser was used to excite four different commonly used fluorochromes, namely Hoechst 33342, Fluo-4, PI and Indo-1, and characteristic fluorescence images were obtained using (455 +/- 15) nm, (540 +/- 15)nm, (580 +/- 16) nm and (500 +/- 15) nm filters respectively. An approach to exciting with a single wavelength, staining with two different fluorochromes, and collecting fluorescence in two separate channels was employed to study mouse preimplantation embryos by 3D and 4D real-time imaging.

[Fluorescence fluctuation spectroscopy with strong background fluorescence--a Monte Carlo approach].

Fluorescence fluctuation spectroscopy is a method in which fluorescence fluctuations arising from a very small sample volume are analysed to obtain brightness, diffusion coefficient and concentration of particles. Using Monte Carlo simulation, the influences of background autofluorescence and noises on fluorescence fluctuation spectroscopy are studied. Results show that a two-component photon counting histogram can effectively remove the effects due to background autofluorescence from low brightness and high concentration components and uniform noise.

[Measurement of methane 13C/12C isotope ratio of slurry gas from oil wells by laser frequency-modulation absorption spectroscopy].

In this paper, we determined the ratio of C13/C12 of methane in slurry gas from oil wells by the method of laser frequency modulation absorption spectroscopy that has many advantages such as high precision, high spectroscopic resolution and rapidly and simply dealing with samples. This technique provided us with a subsidiary method for oil-gas source exploration. The method of laser frequency modulation absorption spectroscopy is based on the method of laser frequency absorption spectroscopy and is more accurate.