Effect of Nuangong zhitong decoction on primary dysmenorrhea in mice

Purpose: To investigate the therapeutic effect of Nuangong Zhitong decoction (NZD) on primary dysmenorrhea (PD) in mice, and its mechanism of action. Methods: Dysmenorrhea was established in female PD mice by intraperitoneal injection of oxytocin following estradiol benzoate pretreatment. The effects of NZD and its active principles (cinnamic aldehyde and cinnamic acid) on PD were determined using body twist method. Serum levels of prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2α) in mice were measured using ELISA. Results: The results showed that NZD dose-dependently reduced oxytocin-induced writhing responses (p < 0.05). Moreover, cinnamic aldehyde and cinnamic acid reduced oxytocin-induced writhing responses in a concentration-dependent manner, with maximal inhibitions of 65.01 and 70.67 %, respectively, and also decreased serum levels of PGE2 and PGF2α in PD mice (p < 0.05). Conclusion: These results indicate that NZD mitigates oxytocin-induced uterine tetanic contraction in mice. Thus, NZD has a potential for development into an anti-dysmenorrheal drug for use in humans

Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament

We report on experimental realization of impulsive rotational Raman scattering from neutral nitrogen molecules in a femtosecond laser filament using an intense self-induced white-light seeding "air laser" generated during the filamentation of an 800 nm Ti: Sapphire laser in nitrogen gas. The impulsive rotational Raman fingerprint signals are observed with a maximum conversion efficiency of ~0.8%. Our observation provides a promising way of remote identification and location of chemical species in atmosphere by rotational Raman scattering of molecules.Comment: 4 pages, 4 figure

Population Redistribution among Multiple Electronic States of Molecular Nitrogen Ions in Strong Laser Fields

We carry out a combined theoretical and experimental investigation on the population distributions in the ground and excited states of tunnel ionized N2 molecules at various driver wavelengths in the near- and mid-infrared range. Our results reveal that efficient couplings (i.e., population exchanges) between the ground state and the excited states occur in strong laser fields. The couplings result in the population inversion between the ground and the excited states at the wavelengths near 800 nm, which is verified by our experiment by observing the amplification of a seed at ~391 nm. The result provides insight into the mechanism of free-space nitrogen ion lasers generated in remote air with strong femtosecond laser pulses.Comment: 18 pages, 4 figure

Remote creation of strong and coherent emissions in air with two-color ultrafast laser pulses

We experimentally demonstrate generation of strong narrow-bandwidth emissions with excellent coherent properties at ~391 nm and ~428 nm from molecular ions of nitrogen inside a femtosecond filament in air by an orthogonally polarized two-color driver field (i. e., 800 nm laser pulse and its second harmonic). The durations of the coherent emissions at 391 nm and 428 nm are measured to be ~2.4 ps and ~7.8 ps respectively, both of which are much longer than the duration of the pump and its second harmonic pulses. Furthermore, the measured temporal decay characteristics of the excited molecular systems suggest an "instantaneous" population inversion mechanism that may be achieved in molecular nitrogen ions at an ultrafast time scale comparable to the 800 nm pump pulse.Comment: 19 pages, 4 figure

Real-time observation of dynamics in rotational molecular wave packets by use of "air laser" spectroscopy

Molecular rotational spectroscopy based on strong-field-ionization-induced nitrogen laser is employed to investigate the time evolution of the rotational wave packet composed by a coherent superposition of quantum rotational states created in a field-free molecular alignment. We show that this technique uniquely allows real-time observation of the ultrafast dynamics of the individual rotational states in the rotational wavepacket. Our analysis also shows that there exist two channels of generation of the nitrogen laser, shedding new light on the population inversion mechanism behind the air laser generated by intense femtosecond laser pulses.Comment: 23 pages, 6 figure