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1.
Opt Express ; 29(10): 14452-14466, 2021 May 10.
Article in English | MEDLINE | ID: mdl-33985168

ABSTRACT

Noise-like quasi-continuous-wave background (qCWB) in a mode-locked fiber laser mediates various multi-pulse dynamics via long-range inter-pulse interactions. This raises a possibility to control multi-pulse phenomena through manipulation of the qCWB, while it has been rarely studied yet. Here, we investigate the qCWB engineering by imposing optomechanically induced impulsive intensity modulations on the qCWB. The mode-locked pulses excite electrostrictively several transverse acoustic resonance modes inside the fiber cavity, which eventually leads to the formation of sharp qCWB modulations regularly spaced in the time domain. In particular, we experimentally demonstrate that the characteristics of the optomechanical qCWB modulations can be adjusted by controlling the in-fiber optomechanical interactions via changing the structure of the fiber core, cladding, and coating. Our observations are supported by directly measured forward stimulated Brillouin scattering spectra of the intracavity fibers.

2.
Opt Express ; 27(2): 1718-1726, 2019 Jan 21.
Article in English | MEDLINE | ID: mdl-30696233

ABSTRACT

Photonic devices that exhibit all-optically reconfigurable polarization dependence with a large dynamic range would be highly attractive for active polarization control. Here, we report that strongly polarization-selective nonlinear optomechanical interactions emerge in subwavelength waveguides. By using full-vectorial finite element analysis, we find, at certain core ellipticities (or aspect ratios), that the forward simulated light scattering mediated by a specific acoustic resonance mode is eliminated for one polarization mode. Whereas, that for the other polarization mode is rather enhanced. This intriguing phenomenon can be explained by the interplay between the electrostrictive force and radiation pressure and turns out to be tailorable by the choice of waveguide materials.

3.
J Ethnopharmacol ; 142(1): 213-20, 2012 Jun 26.
Article in English | MEDLINE | ID: mdl-22579675

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Rhus parviflora is referred as 'Tintidikah' in traditional medicinal system of south Asia (Ayurveda). It is used in treatment of Vata vikara, a condition related to neurological complications as well as cure for stomach disorders. MATERIALS AND METHODS: Dried and powdered fruits of R. parviflora were extracted with 80% aqueous methanol (RPME). The concentrated extract was successively partitioned with distilled water (DW), ethyl acetate (EtOAc), and n-butanol (n-BuOH). All extracts, as well as isolated biflavonoids from R. parviflora, were evaluated for their affinity to the benzodiazepine binding site of GABA(A) receptor. The sedative-hypnotic effects of the fractions were evaluated by measuring sleep latency and sleep duration during pentobarbital-induced sleep in mice after oral administration of the extract fractions. RESULTS: Oral administration of RPME (125 mg/kg, 250 mg/kg, 500 mg/kg, and 1000 mg/kg) produced a dose-dependent decrease in sleep latency and an increase in sleep duration in mice treated with pentobarbital. The methanol extract produced a hypnotic effect that was fully blocked by ³H-Ro 15-1788 flumazenil (FLU). Further, among the solvent fractions, the ethyl acetate fraction exhibited significant activity. Among the isolated compounds, biflavonoids mesuaferrone B (1), rhusflavone (3), and agathisflavone (4) competitively inhibited FLU binding with a K(i) of 0.280 µM, 0.045 µM, and 0.091 µM, respectively. In addition, analysis of the sedative-hypnotic effects of rhusflavone, as well as those of the ethyl acetate, n-butanol, and distilled water fractions revealed that the modulation of both the ethyl acetate fraction and biflavonoid rhusflavone (3) are the most potent in inducing sleep. CONCLUSION: The presence of conjugated ketone and C6-C8″ biflavonoid linkage in rhusflavone may be responsible for BZD-site of the GABA(A) leading to decrease in sleep latency and increase sleep duration.


Subject(s)
Biflavonoids/pharmacology , Hypnotics and Sedatives/pharmacology , Plant Extracts/pharmacology , Receptors, GABA-A/physiology , Rhus , Sleep/drug effects , Animals , Biflavonoids/analysis , Biflavonoids/metabolism , Fruit , Male , Mice , Mice, Inbred ICR , Plant Extracts/analysis , Plant Extracts/metabolism , Rats , Rats, Sprague-Dawley , Sleep/physiology
4.
J Ethnopharmacol ; 132(1): 225-32, 2010 Oct 28.
Article in English | MEDLINE | ID: mdl-20804838

ABSTRACT

AIM OF THE STUDY: Many medicinal plants have been used for treatment of insomnia in Asia. However, scientific evidence and precise mechanism for their sedative-hypnotic activity have not been fully investigated. Thus, we investigated the binding activity of the oriental plant extracts (mainly from Korea and Japan) to the well-known molecular targets for sleep regulation, GABA(A) and 5-HT(2C) receptors. Following the binding assay, sedative-hypnotic effects of the extracts with high affinity were examined in an animal model of sleep. MATERIALS AND METHODS: Aqueous and ethanol extracts of 15 medicinal plants were tested for binding at the benzodiazepine site of GABA(A) receptor and 5-HT site of 5-HT(2C) receptor. The sedative-hypnotic effects of selected extracts were evaluated by measuring the sleep latency and sleep duration during pentobarbital-induced sleep in mice after oral administration of extracts. RESULTS: In the GABA(A) assay, the ethanol extracts of licorice and danshen displayed concentration-dependent, high affinity binding, whereas in the 5-HT(2C) assay, the ethanol extracts of ginseng and silk tree showed high affinity. Among these extracts we tested previously uncharacterized licorice and silk tree for hypnotic effects. We found the ethanol extracts of licorice and silk tree significantly decreased sleep latency and increased sleep duration in pentobarbital-induced sleep. CONCLUSIONS: We demonstrate for the first time that licorice and silk tree have the sedative-hypnotic activity possibly by modulating GABA(A) and 5-HT(2C) receptors. We propose that licorice and silk tree might be effective candidates for treatment of insomnia.


Subject(s)
Hypnotics and Sedatives/therapeutic use , Medicine, East Asian Traditional , Plant Extracts/therapeutic use , Plants, Medicinal/chemistry , Receptor, Serotonin, 5-HT2C/metabolism , Receptors, GABA-A/metabolism , Sleep Initiation and Maintenance Disorders/drug therapy , Animals , Asia , Hypnotics and Sedatives/isolation & purification , Hypnotics and Sedatives/pharmacology , Male , Mice , Mice, Inbred ICR , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Plants, Medicinal/growth & development , Protein Binding , Radioligand Assay , Sleep/drug effects , Sleep Initiation and Maintenance Disorders/metabolism
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