[The influence of temperature on the orientation of pigments in PS II].

The effect of temperature on the orientation of pigment in PSII was studied by the fluorescence excitation spectra and polarization fluorescence spectra of spinach thylakoid solution. The experimental results showed that in the temperature range of 15-45 degrees C the absorption band of chl a at 436 nm at room temperature red-shifted with increasing temperature. The excitation spectra intensity reached the maximum at the temperature of 35 degrees C, but greatly reduced with temperature at 65 and 78 degrees C. In the polarization fluorescence spectra the fluorescence peak of PSII didn't change with temperature from 15 to 45 degrees C. It was also found that the calculated fluorescence polarization degree increased with the temperature in the entire temperature range. The analysis indicated that temperature would affect the orientation of the pigments in PSII and the coupling strength between pigments so to change photosynthetic efficiency. The results will give a certain reference for the study of the energy absorption and transmission, regulation mechanism and also on solar cell materials.

Numerical simulation of the influence of the elastic modulus of a tumor on laser-induced ultrasonics in soft tissue.

The influence of the elastic modulus of a tumor (EMT) on the laser-generated thermoelastic force source and ultrasound waves are investigated by using the finite element method. Taking into account the effects of thermal diffusion, optical penetration, and finite duration of laser pulse, the transient temperature distribution is obtained. Applying this temperature field to structure analyses as thermal loading, the thermoelastic stress field and laser-induced ultrasound wave in soft tissues are obtained. The results show that there is a linear correlation between the maximum compressive stress and the elastic modulus of tissues. It is also shown that the features and frequency regions of the laser-induced ultrasound waveform have a close relationship with the EMT, which has been further verified by a corresponding experiment.

[Hydration of liquid ethanol probed by Raman spectra].

In order to study the concentration dependence of the molecular interactions in ethanol-water hydrogen bonded system, Raman spectra of ethanol-water mixtures with different water contents were obtained at room temperature. It was found that the positions of the 3 C-H stretching vibration bands of ethanol molecule located in the range of 2 800-3 050 cm(-1) would generally present blue shifts when more water was added into the mixture; at the same time, however, the C-O stretching vibration band located at around 1 048 cm(-1) showed an opposite behavior. The different hydration, which is induced by hydrogen bonding, which happened in different concentration mixtures, was thought to be responsible for this situation, the hydration process of liquid ethanol was thus deduced: when adding a small amount of water into pure ethanol, and clusters containing one water molecule and several ethanol molecules were formed instead of ethanol self-association short chain clusters existing in pure ethanol; the clusters would combine more water molecules to form ringlike clusters through hydrogen bond association when adding more water into the mixture, then a temporary saturation would be seen when the volume percent of water reached 50%, and this saturation state would last until the water content reached 70 vol%; after that, the large number of water molecules would dissociate the ringlike clusters to smaller clusters and then associate to the ends of these dissociated clusters through hydrogen bonding; in addition, the improper hydrogen bonding between oxygen atom of water molecule and C-H bond of ethanol molecule is considered to be formed after the content of water reached a high value.

[Study on the elements of the fluorescence spectra emitted from ethanol-water mixture].

The 236 nm UV-light was adopted to excite the 10 ethanol-water mixture samples in which the volume percent of ethanol ranges from 10% to 95%, and the Gaussian decomposition method was used to decompose the fluorescence spectra obtained above to Gaussian curves, where every Gaussian curve can be attributed to the fluorescence emission of a certain kind of luminescent ethanol-water cluster, which is formed by the association between water molecules and ethanol molecules. It was found that every spectrum of the certain binary mixture contains 8 Gaussian elements, and the emission density and peak wavelength of each element were also obtained. The authors studied the mechanism of the fluorescence emission of the mixtures based on the structural characters of fluorescence substances and concluded that the water molecules play an important role in the fluorescence emission: they enlarge the conjugate system as the electron donors; they bridge the ethanol molecules to form 8 kinds of new clusters at the same time, and the conformation of the clusters is rings and chains composed by several rings. Through the peak wavelengths of the Gaussian elements decomposed from the certain concentration spectrum the authors got the information about the relative size of the new clusters, i.e. the clusters are bigger or show chain structures when the peak wavelength of the Gaussian curves is located at the longer positions. The emission transition energies of the 8 kinds of new clusters were also calculated. In addition, it was found that there was a certain relation between the half-width and the association situation. The research contributes to the study of ethanol-water cluster structures and their physical and chemical characteristics.

[Identification of protoporphyrin IX fluorescence spectrum in human blood serum by biorthogonal spline wavelet].

For the low content and weak fluorescence intensity, usually presenting shoulder peaks, it is often hard to locate protoporphyrin IX and identify its fluorescence intensity in human blood serum. Biorthogonal spline wavelet may work for the identification of its weak signal Superimposing protoporphyrin IX fluorescence signal on the background of blood serum spectrum, a series of varied fluorescence spectra of them can be obtained. The protoporphyrin IX fluorescence signal from blood serum background is separated and the fluorescence spectrum can be divided into corresponding discrete approximate signals (a1-a7) and discrete details signals (d1-d7) by biorthogonal spline wavelet bior 5.5 seven levels decomposition. The signal frequency shows a gradual decrease with increasing decomposition. Protoporphyrin IX fluorescence peak emerges when it comes to the 7th decomposition. The signal peak shifts about 2.5 mm downwards as the signal intensity decreases, whereas the signal peak from wavelet filter remains where it was. As the synchronization disappears between signal intensity and signal peak, usually it is hard to assure the fluorescence intensity and peak location. However, signal from wavelet filter may ignore the affect and identify the protoporphyrin IX in human blood serum with the help of biorthogonal spline wavelet. As the linear alternation of wavelet and discrete details signals maintain their inborn linear relations, the authors can carry out the qualitative and quantitative analysis for the precise content and quantity of protoporphyrin IX in blood serum, which provides a feasible method for the application of blood serum fluorescence spectrum to tumor early diagnosis.

[Fluorescence spectrum analysis system for protoporphyrin IX in serum based on wavelet transform].

Protoporphyrin IX is an important kind of organic compound for vital movement, and can be used as the sign of tumour blood. Human protoporphyrin IX content in serum is very low, and affected by various factors. The serum fluorescence spectrum analysis system based on wavelet transform was used to discriminated the protoporphyrin IX weak signals. The protoporphyrin IX fluorescence spectrum was obtained by a multi-function spectrum measuring system, and decomposed several times by wavelet transform to distinguish the noise and spectrum signals. The fluorescence spectrum can be divided into corresponding discrete approximations signals (a1-a6) and discrete details signals (d1-d6) by six times of decomposition, showing the signal frequency decreasing with decomposition times increasing and the protoporphyrin IX fluorescence character peak appears here. The weak signals were discriminated and the exactly component and quantity can be acquired for further analysis. So it can be analysed quantitatively. The researches in the present paper provide the potential application in the diagnosis of incipient tumous using the serum fluorescence spectrum

[Spectroscopy research on cholesterol in hypercholesterolemia serum].

The cholesterol with different concentration in hypercholesterolemia serum was studied by the method of spectroscopy technology. The absorption and fluorescence spectra of normal human serum and hypercholesterolemia serum were obtained respectively; the spectral characteristic of each sample and the difference between two kinds of samples were discussed too. The results indicate that the absorption and fluorescence spectra of hypercholesterolemia serum are different from those of normal human serum. The absorptivity and the fluorescence intensity of hypercholesterolemia serum are both higher than those of normal human serum. Besides, there are new absorptive peaks and new fluorescence peaks in the spectrogram. Thus, the abnormalism of cholesterol in serum can be judged by comparing the absorption and fluorescence spectra. The researches in the present paper provide an experimental foundation for the diagnosis of cholesterol in blood.