Time-dependent wave packet averaged vibrational frequencies from femtosecond stimulated Raman spectra.

Femtosecond stimulated Raman spectroscopy (FSRS) on the Stokes side arises from a third order polarization, P(3)(t), which is given by an overlap of a first order wave packet, |Ψ2(1)(pu,t)>, prepared by a narrow band (ps) Raman pump pulse, Epu(t), on the upper electronic e2 potential energy surface (PES), with a second order wave packet, <Ψ1(2)(pr(∗),pu,t)|, that is prepared on the lower electronic e1 PES by a broadband (fs) probe pulse, Epr(t), acting on the first-order wave packet. In off-resonant |FSRS, Ψ2(1)(pu,t)> resembles the zeroth order wave packet |Ψ1(0)(t)> on the lower PES spatially, but with a force on |Ψ2(1)(pu,t)> along the coordinates of the reporter modes due to displacements in the equilibrium position, so that <Ψ1(2)(pr(∗),pu,t)| will oscillate along those coordinates thus giving rise to similar oscillations in P(3)(t) with the frequencies of the reporter modes. So, by recovering P(3)(t) from the FSRS spectrum, we are able to deduce information on the time-dependent quantum-mechanical wave packet averaged frequencies, ω̄j(t), of the reporter modes j along the trajectory of |Ψ1 (0)(t)>. The observable FSRS Raman gain is related to the imaginary part of P(3)(ω). The imaginary and real parts of P(3)(ω) are related by the Kramers-Kronig relation. Hence, from the FSRS Raman gain, we can obtain the complex P(3)(ω), whose Fourier transform then gives us the complex P(3)(t) to analyze for ω̄j(t). We apply the theory, first, to a two-dimensional model system with one conformational mode of low frequency and one reporter vibrational mode of higher frequency with good results, and then we apply it to the time-resolved FSRS spectra of the cis-trans isomerization of retinal in rhodopsin [P. Kukura et al., Science 310, 1006 (2005)]. We obtain the vibrational frequency up-shift time constants for the C12-H wagging mode at 216 fs and for the C10-H wagging mode at 161 fs which are larger than for the C11-H wagging mode at 127 fs, i.e., the C11-H wagging mode arrives at its final frequency while the C12-H and C10-H wagging modes are still up-shifting to their final values, agreeing with the findings of Yan et al. [Biochemistry 43, 10867 (2004)].

[Study on the Anisotropy of Collagenours Fibers in Articular with Infrared Imaging].

Formalin solution has been widely used to solidify the organization of articular cartilage and prevent tissue decomposition in long-time measurement. However, it was rarely investigated that the structural anisotropy changes of collagen fiber (fixation) of articular cartilage when it was immersed in formalin. In this paper, Fourier transform infrared spectroscopic imaging with polarization technique was used to investigate the anisotropic structure change of collagen fiber of articular cartilage fixed in formalin through the absorbance change of Amide I and Amide II with immersing time and polarization direction. The degree of anisotropy of collagen fiber in cartilage was characterized with fitting related coefficient of absorbance. The anisotropy of Amide I and Amide II became stronger with immersing extension of articular cartilage in formalin, and the amide I showed more remarkable anisotropy. It was concluded that the formalin solution induced new crosslinks of collagen, which gradually strengthened the collagen fiber anisotropy and was helpful for the structural analysis of the articular cartilage. The study will be significant for the preparation, preservation and anisotropy research of cartilage specimen.

[Clinical effect of milkvetch extract oral liquid in preventing and treating children's recurrent respiratory tract infection].

OBJECTIVE: To explore and compare the clinical effects of three immuno-potentiators and their influence on immune function in preventing and treating recurrent respiratory tract infection (RRI). METHODS: Seventy-two children with RRT were assigned to three groups, the 23 patients in the M group treated with milkvetch extract oral liquid, the 23 in the P group treated by P-transfer factor and the 26 in the U group treated by Utilins injection. Clinical effect was compared among three groups after treatment, and changes of T cell subgroups as well as immune antibodies were detected before and after treatment. RESULTS: The markedly effective rate in the M, P, and U group was 69.6%, 65.2%, and 73.0% respectively, and the total effective rate 87.0%, 82.6%, and 92.3%, showing an insignificant difference among them (all P>0.05). After treatment, the levels of CD3+, CD4+ and CD4+/CD8+ rose obviously in the three groups (all P<0.05); levels of CD8+ in the M group and the P group lowered significantly (P<0.05, P<0.01), but with no significant difference among three groups in the changes of T cell subgroups (all P>0.05). Serum levels of IgG in all the three groups, IgA in the P group and the M group, and IgM in the M group and the U group rose significantly (P<0.05 or P<0.01), with statistical difference presented in comparing of IgA level in the P group with that in the other two groups (P<0.01). CONCLUSION: The clinical effects and the outcomes of immunological indexes' changing are similar in RRI patients treated by the three immuno-potentiators. They all can enhance the immunological function of the organism, strengthen the disease-resistant ability of patients, and reduce the incidence of RRI. Among them, the milkvetch extract oral liquid is worthy of spreading due to its lower cost, simple administration, exemption from painful injection, and good compliance.