Polarization-multiplexed, single-cavity dual-comb fiber laser based on a birefringent crystal and a saturable absorber.

We introduce a calcium carbonate birefringent crystal into an Er-fiber laser mode-locked by a saturable absorber, where dual-comb ultrashort pulses with orthogonal polarization have been obtained. The two ultrashort pulse trains from the laser exhibit polarization contrast ratios of 30 dB and 20 dB, indicating that the dual-comb mode-locking is due to the polarization-multiplexing mechanism. The dual-comb ultrashort pulses have central wavelengths of 1564.41 nm and 1564.51 nm, and pulse durations of 825 fs and 805 fs respectively. The optical spectra and pulse durations of the asynchronous ultrashort pulses are nearly identical, so that the output of the laser could be directly used for dual-comb applications. Besides, the repetition-rate difference of the two mode-locked pulses is 673 Hz, while its drift is only 0.093 Hz within 2 hours' time. The low drift of the repetition-rate difference manifests the single-cavity dual-comb Er-fiber laser has a high stability and high common-mode noise suppression. At last, we have tested the dual-comb fiber laser in a ranging experiment, where clear interferogram signal can be observed. The experimental results prove that this single-cavity dual-comb Er-fiber laser based on the birefringent crystal and saturable absorber can be a potential source for spectroscopy, optical imaging, absolute distance measurement and other dual-comb applications.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs.

INTRODUCTION: Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology. AREAS COVERED: This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery. EXPERT OPINION: Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Rapid identification and analysis of the major chemical constituents from the fruits of Sapindus mukorossi by HPLC-ESI-QTOF-MS/MS.

In the present work, high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) has been used for the identification of the major chemical constituents from the fruits of Sapindus mukorossi. A total of 31 peaks were identified based on their accurate masses and fragmentation characteristics. Among these 9 acyclic sesquiterpene oligoglycosides and 8 triterpenoid saponins were reported from the fruits of Sapindus mukorossi for the first time. This study demonstrates the potential of HPLC-ESI-QTOF-MS/MS for analysis and identification of acyclic sesquiterpene oligoglycosides and triterpenoid saponins.