Xiufeng Lan

Investigation on the fluorescent spectral characteristic of ethanol solution induced by different wavelength UV-light

A thorough analysis of the ultraviolet absorption spectra and light induced fluorescence (LIF) spectral characteristics of ethanol solutions is carried out and discussed in theory and in experiment. The results indicate that ethanol solution can absorb UV-light with the wavelength less than 250nm, and can emit very strong fluorescence when excited by these ultraviolet lights. While the wavelengths of excited lights increase, the fluorescent spectral peaks are apparently red-shifted accordingly. As the ethanol solution concentration increases, the fluorescent spectral peaks are also red-shifted. Furthermore, the physical mechanism of absorption and fluorescence emission of ethanol molecule induced by UV light is analyzed based on the theory of molecule orbital structure. The red-shifted reasons of spectral peaks as the excited light wavelength and the solution concentrations changing are also explained. Investigation on the intrinsic fluorescence spectrum of ethanol solution and its characteristics will contribute to the study of the fluorescence spectra when ethanol serves as solute and hydrolysis catalyst.

Fluorimetric determination of cholesterol in hypercholesterolemia serum

With the increase of people’s living standard and the changes of living form, the number of people who suffer from hypercholesterolemia is increasing. It is not only harmful to heart and blood vessel, but also leading to obstruction of cognition. The conventional blood detection technology has weakness such as complex operation, long detecting period, and bad visibility. In order to develop a new detection method that can checkout hypercholesterolemia conveniently, spectroscopy of cholesterol in hypercholesterolemia serum is obtained by the multifunctional grating spectrograph. The experiment results indicate that, under the excitation of light-emitting diode (LED) with the wavelength at 407 nm, the serum from normal human and the hypercholesterolemia serum emit different fluorescence spectra. The former can emit one fluorescence region with the peak locating at 516 nm while the latter can emit two more regions with peaks locating at 560 nm and 588 nm. Moreover, the fluorescence intensity of serum is non-linear increasing with the concentration of cholesterol increases when the concentration of cholesterol is lower than 13.8 mmol/L, and then, with the concentration of cholesterol increase, the fluorescence intensity decreases. However, the fluorescence intensity is still much higher than that of serum from normal human. Conclusions can be educed from the experiments: the intensity and the shape of fluorescence spectra of hypercholesterolemia serum are different of those of normal serum, from which the cholesterol abnormal in blood can be judged. The consequences in this paper may offer an experimental reference for the diagnosis of the hypercholesterolemia.

The mechanism researching on the red-shifted rule of human blood fluorescent spectra

The fluorescent spectra of human blood with different concentration induced by different wavelength LED light are reported in this paper. The phenomenon that fluorescence peaks are apparently red-shifted with the increase of blood concentration is analyzed and the mechanism is given a reasonable explanation. The results indicate that the peak is shifted following the rule of e-exponent with the increase of the blood concentration. The mechanism of different energy transfer with different fluorescent areas is analyzed from the theory of energy transfer. The resonance energy transfer is the primary reason of the fluorescent spectra peaks. The concept of the idea fluorescence and the inner fluorescence is also brought forward in this paper. The research will give refer intrinsic fluorescence diagnostic techniques of organic tissue.

Physical analysis on laser-induced cerebral damage

Experimental investigation on cerebral damage of adult SD rats induced by 532nm CW laser was performed. Tissue heat conductive equation was set up based on two-layered structure model. Finite difference algorithm was utilized to numerically simulate the temperature distribution in the brain tissue. Allowing for tissue response to temperature variation, free boundary model was used to discuss tissue thermal coagulation formation in brain. Experimental observations show that thermal coagulation and necrosis can be caused due to laser light absorption. The result of the calculation shows that the process of the thermal coagulation of the given mode comprises two stages: fast and slow. At the first stage, necrosis domain grows fast. Then necrosis domain growth becomes slower because of the competition between the heat diffusion into the surrounding undamaged tissue and the heat dissipation caused by blood perfusion. At the center of coagulation area no neuron was observed and at the transitional zone few nervous cells were seen by microscope. The research can provide reference data for developing clinical therapy of some kind of encephalic diseases by using 532nm laser, and for making cerebral infarction models in animal experiment.

Investigation of momentary mechanical effects while Q-switched laser acts on dermal pigmented lesions

Clinical application shows that the Q-switched laser therapy on pigmented lesions based on the principle of selective thermolysis is good in efficiency. But the mechanism of this method of treatment remains unclear yet. Elementary researches are up to date restricted to the levels of morphological observation mainly. The beginning split second process within which laser pulse is interaction with dermal tissues has not been investigated in detail. This process also includes a series of sub processes of super high intensity of photo thermotics, plasma shock wave, super express boil inflation, et. Researches of experimental tests to the momentary processes mentioned above have been performed in this project. The results suggest that laser ablation impact and shock wave induced by laser play important rules in the process.

Researching on the fluorescence spectra of acetic acid solutions induced by different wavelength UV light

Acetic acid solution can emit visible fluorescence when induced by UV-light. With emitting spectrum profiles dissimilar on the whole, the fluorescent intensity changes too when the excited light alters from 230nm to 300nm. There are two spectral bands on the whole, one central wavelength is located at 307nm and the other is at 400nm. The relationship between the fluorescence relative intensity and the excited-light wavelength is described in polynomial fit. The optimal excited light is obtained both by the experiment data and the polynomial fit of the data. Investigation on the intrinsic fluorescence spectrum of acetic acid solution and its characteristics will contribute to the study of the fluorescence spectra when acetic acid serves as a solute and hydrolysis catalyst. Especially, this study will also help to offer the experiment basic for the theoretic research of the interaction of acetic acid and water molecule.

Investigation on the fluorescence spectra of thioredoxin reductase from human brain

The technique of fluorescence spectroscopy is applied to study thioredoxin reductast (TrxR) in the cells of human brain. Experimental results show that, by the ultraviolet light irradiation (λmax=253.7nm), TrxR is able to emit two striking spectral bands of 287nm to 484nm and 560nm to 720nm. The spectral profile also consists of some narrow spike-like bands atop these two broad bands. With the concentration of TrxR decreases, the narrow spike-like bands disappear little by little. Furthermore, physical and biochemical mechanisms of fluorescence production for ultraviolet light-induced TrxR spectra and its characteristics are analyzed. The new spectroscopic information suggested in this paper may represent an effort of better understanding of the structure and conformation changes of TrxR.

Investigation on fluorescent spectra of blood induced by lights of different wavelengths

In order to investigating the effect of wavelength on laser blood therapy, we test the fluorescent spectra of human blood. The wavelengths of exciting lights are 530 nm and 632.8 nm respectively. The result indicates that the light of 530 nm induces much stronger fluorescence, and the emitting spectra induced by 632.8 nm is rather different from the spectra induced by the light of 530 nm. This result suggests that the processes of interaction between laser and blood vary with the wavelength of the radiating lights, so the biological effects of the light to blood can differ with wavelength. These facts might have some meanings to the further research for explaining mechanisms of the laser blood therapy.

Fluorometric determination of whole blood with various excitation wavelengths

Autofluorescence spectra from whole blood of laboratory rat are measured in this paper. The excitation lights are light emitting diode (LED), Ar+ laser, and He-Ne laser with the wavelength located at 457nm, 457.9nm, and 632.8nm respectively. The three spectral profiles are found to be substantially different, each displaying its own characteristic fluorescence bands. Ar+ laser-induced spectrum has very rich and sharp peaks. The LED-induced one has the strongest and widest fluorescence bands. And the intensity of the spectrum induced by He-Ne laser is much lower than the former two. Comparisons of those three fluorescence spectra indicate that Ar+ laser induced spectrum can show partly fine structure of blood cells. Based on the theoretical analysis, it is presented that the absorption of the fluorophores in blood cells to the wavelength of exciting light has definite selectivity, which depend on energy level structure and state of the fluorophores.

The comparison of fluorescent spectra on acetic acid and ethanol solutions

Acetic acid and ethanol solutions can emit fluorescence when induced by 253.7nm UV-light. In this paper, fluorescence spectral characteristics of acetic acid and ethanol solutions are analyzed and studied in theory and in experiment. The results indicate that both acetic acid and ethanol can emit two fluorescence spectral bands, one is from 330nm to 493nm and the other is from 534nm to 665nm. The emitting fluorescence intensity is very sensitive to the solutions concentrations, and fluorescence quenching occurs in some solutions of the two samples. Furthermore, the physical mechanism of fluorescence emission of acetic acid and ethanol molecules is analyzed based on the theory of molecule orbital structure, and the quenching mechanism are studied by the dynamic process. Investigation on the native fluorescence spectrum of the two solvent and their characteristics will contribute to the study of the fluorescence spectra when they serve as solute, hydrolysis catalyst and food additive.