Adaptive Bayesian algorithm for achieving a desired magneto-sensitive transition.

Bayesian methods that utilize Bayes' theorem to update the knowledge of desired parameters after each measurement are used in a wide range of quantum science. For various applications in quantum science, efficiently and accurately achieving a quantum transition frequency is essential. However, the exact relation between a desired transition frequency and the controllable experimental parameters is usually absent. Here, we propose an efficient scheme to search the suitable conditions for a desired magneto-sensitive transition via an adaptive Bayesian algorithm and experimentally demonstrate it by using coherent population trapping in an ensemble of laser-cooled 87Rb atoms. The transition frequency is controlled by an external magnetic field, which can be tuned in realtime by applying a d.c. voltage. Through an adaptive Bayesian algorithm, the voltage can automatically converge to the desired one from a random initial value only after few iterations (N ≥ 10). The response time is limited by the time of obtaining the spectrum signal, which is about 50 s for 10 iterations in our experiment. In particular, when the relation between the target frequency and the applied voltage is nonlinear (e.g., quadratic), our algorithm shows significant advantages over traditional methods. This work provides a simple and efficient way to determine a transition frequency, which can be widely applied in the fields of precision spectroscopy, such as atomic clocks, magnetometers, and nuclear magnetic resonance.

Laser frequency stabilization via bichromatic Doppler-free spectroscopy of an 87Rb D1 line.

We demonstrate a bichromatic Doppler-free spectroscopy of an 87RbD1 line by using a dual-frequency, counterpropagating laser field with orthogonal linear polarizations. A reversed Doppler-free resonance dip is observed in the dual-frequency scheme, and a significant improvement of frequency discrimination curve is acquired due to the coherent population trapping (CPT) effect. The influence of the static magnetic field and laser intensity on the spectroscopy is studied in both single- and dual-frequency schemes. After locking the laser frequency to the 87RbD1 line in the dual-frequency stabilization scheme, the beat note fractional frequency stability is at the level of 7×10-12 at 1 s integration time. This technique can be used in various applications, such as CPT atomic clocks, laser spectroscopy, quantum optics, and laser-cooling experiments.

Simple and effective coupling technique for polarization maintaining fibers.

We present a simple and effective technique for coupling free-space laser beams into polarization maintaining fibers (PMFs) with high coupling efficiency. We measure both input and output laser beam sizes near the PMF by using the knife-edge method and build a suitable two-lens system for beam shaping according to the difference between those two beam sizes. For tapered amplifiers, we achieve high coupling efficiency above 70% with the help of the seeding mirrors. For external cavity diode lasers, we obtain high coupling efficiency above 80%. In addition, we demonstrate that theoretical maximum coupling efficiency can be approached by using a mode-filtered beam. Our technique is easy to implement and suitable for many applications such as coherent optical communication, atomic physics experiments, and precision measurements.

Chlorogenic Acid Exerts Beneficial Effects in 6-Hydroxydopamine-Induced Neurotoxicity by Inhibition of Endoplasmic Reticulum Stress.

BACKGROUND Chlorogenic acid (CGA), a dietary polyphenol derived from many plants, has been previously reported to exert neuroprotective properties. However, its pharmacological role in Parkinson's disease (PD) and the underlying mechanisms are unclear. MATERIAL AND METHODS In the present study, we investigated the beneficial effects of CGA against the toxicity of 6-hydroxydopamine (6-OHDA) in animal and cellular models. One week after 6-OHDA administration, the behavioral activities of rats were determined by rotarod test and apomorphine-induced rotational test. The viability and apoptosis of SH-SY5Y cells following 6-OHDA exposure were determined by MTT assay and annexin V-FITC/PI double staining, respectively. The activities of antioxidant enzymes in the rat striatal tissues and SH-SY5Y cells were detected by ELISA. RESULTS The results demonstrated that 6-OHDA-induced PD-like behavioral impairments of rats were significantly forestalled by CGA administration. The increased apoptosis and reduced activities of antioxidant enzymes in the striatum of 6-OHDA-lesioned rats were also attenuated by CGA. Moreover, in an in vitro experiment, the impaired viability and enhanced apoptosis of 6-OHDA-injured SH-SY5Y cells were significantly restored by CGA pretreatment. In addition, CGA also obstructed 6-OHDA-induced ROS production and endoplasmic reticulum (ER) stress in SH-SY5Y cells. CONCLUSIONS Taken together, these data show that CGA might be an effective neuroprotective compound that mitigates oxidative stress and ER stress in PD.

Knockdown of lncRNA SNHG1 alleviates oxygen-glucose deprivation/reperfusion-induced cell death by serving as a ceRNA for miR-424 in SH-SY5Y cells.

Objective: Long non-coding RNAs (lncRNAs) are theorized to serve a critical role in cerebral ischemia/reperfusion injury. The purpose of this study was to determine whether knockdown of lncRNA SNHG1 protected against oxygen-glucose deprivation/reperfusion (OGD/R)-induced cell death in vitro and to investigate the underlying mechanisms. Methods: The expression levels of SNHG1 and miR-424 were detected by RT-qPCR analysis. The expression levels of apoptosis-related proteins were detected by western blot analysis. Cell viability and apoptosis were detected by MTT assay and flow cytometric analysis, respectively. Bioinformatic prediction and dual-luciferase reporter assay were performed to study the interaction between SNHG1 and miR-424. Results: The results showed that SNHG1 expression level was increased in OGD/R-treated SH-SY5Y cells, and knockdown of SNHG1 alleviates OGD/R-induced apoptosis and mitochondrial dysfunction in SH-SY5Y cells. Moreover, we found that SNHG1 might serve as a ceRNA for miR-424 in SH-SY5Y cells, and rescue experiments further confirmed that miR-424 inhibitor blocked the beneficial role of SNHG1 knockdown in OGD/R-treated SH-SY5Y cells. Conclusion: Taken together, this research supported the first evidence that lncRNA SNHG1 regulates OGD/R-induced cell death through serving as a ceRNA for miR-424 in SH-SY5Y cells.