Search

Controlling the flow of light is fundamental for on-chip optical signal processing. In this paper, we investigate how to realize high contrast, high unidirectional transmission rate, and reconfigurable nonreciprocal light transmission, based on a nonlinear nanocavity asymmetrically side-coupled with a specially designed slow-light waveguide. We analytically and numerically demonstrate that the unusual multiple threshold pump power points for trigging the photon transitions between bistable states, as well as the sensitivity of the dynamic interactions to the relative delay time between the signal light and pump pulse, play crucial roles in this optical diode system. Based on these findings, a high contrast (over 22 dB) and high unidirectional transmission rate (over 70%) optical diode is achieved. More importantly, the conducting direction of the optical diode can be controllably reversed, without the need of changing the signal's wavelength or power as usually done. This approach is promising in the fields of optical information processing and quantum computing. [ABSTRACT FROM AUTHOR]

Choriocarcinoma (CC) is a malignant trophoblastic tumor that occurs in women of childbearing age. Its cure rate could be over 90% following single drug or multidrug chemotherapy with methotrexate, 5-fluorouracil and etc. Chemoresistance is the main cause of treatment failure in CC, and the mechanisms have yet to be elucidated. Most of the previous works on the chemoresistance of CC focused on the transcript and protein levels, and much less attention was put on the metabolic level. In this study, the metabolomic phenotypes of two lines of CC cell, methotrexate-resistant cell (JEG3R) and methotrexate-sensitive cell (JEG3), as well as the medium extracts, were investigated using an NMR-based metabonomics method. The results showed that the chemoresistance of CC was likely related to disturbed glucose metabolism. Glucitol accumulation was observed only in the JEG3R cell line, suggesting the involvement of aldose reductase in the development of chemoresistance. In addition, methotrexate chemoresistance was also associated with lactate accumulation and stimulated alanine synthesis to fuel the Krebs cycle. The levels of amino acids, nucleotides and phosphocholine in the resistant line showed significant differences from the non-resistant line, and positive correlations with the proliferation rate of CC. This study provided insights into the chemoresistance of CC from the metabolism aspect.

Gut microbiota is important for human health. The complex relationship between intestinal flora and bile acid profile has been studied previously. However, few previous studies have determined the profile and functions of bile acids in different intestinal segments, and whether they are related to the distribution of intestinal flora. In this paper, we measured the distribution of bile acids in different intestinal segments of male and female C57BL/6 mice with ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-QqQ-MS) based targeted metabonomics analysis and nuclear magnetic resonance (NMR) based untargeted metabonomics analysis. Gender difference in distributions of bile acids were observed, which was more evident in the lower parts of intestine than in the upper part of intestine, especially in the cecum segment. This might be related to the abundance of gut microflora in different intestine segments. This study provided metabolic phenotypes of bile acids in mice of different genders, and demonstrated their interactions with gut microbiota.

We investigate the physical origin of energy transfer from an incident light with frequency w to a resonant mode via a linear photonic crystal microcavity. By delicate design of the resonant structure, it is found that the energy conversion efficiency can be greatly improved near the frequency of the incident light. In this way, we can precisely control the frequency of the output light, which is very important for frequency conversion in laser emitting devices and other fields. We also study the dynamic evolvement process in the time domain, and the simulation results show good agreement with the theoretical predictions. OCIS codes: 230.7405, 230.5750, 230.5298.