Search

High sensitive underwater wireless optical communication (UWOC) in shallow water or FSO-UWOC convergent applications suffers severely from solar noise and other background noise interference. This paper presents experimental demonstrations of broadband background noise resistant air-water and underwater wireless optical communication by using a pair of spectrum matched 852 nm Cs atomic Faraday line laser and filter, with a narrow passband of only 1 GHz. Experimental results show that by using the Faraday atomic line laser and filter, the Q factor can be improved by 3.37 dB compared to using the interference filter, and 14.67 dB compared to system without using noise resistant filter. A numerical model for UWOC system performance affected by broadband background noise with various filtering conditions is presented, where both the numerical and experimental results match each other quite well. Based on the experimental results substantiated model, performance of UWOC under solar noise interference is numerically studied. The numerical results show that under strong solar noise interference, the maximum depth of the receiver is extended from 0.77m to 3.79 m for FSO-UWOC system and from 0.87m to 3.54m for UWOC system. It proves that FADOF can provide considerable performance improvement for both UWOC and FSO-UWOC system with broadband background noise interferences.

In this study, we determined the composition of microorganisms in the spontaneous/inoculated fermentation process of persimmon (Diospyros kaki L., China) wine for the first time and compared the similarities and differences of microbial succession, change in volatile compounds, and variations in amino acids. We found that spontaneous persimmon wine fermentation (SPF) resulted in lower bacterial community diversity and higher fungi community diversity than inoculated persimmon wine fermentation (IPF). SPF increased the proportion of esters in overall volatile compounds (29.9 % vs 18.9 %) at the end of fermentation. According to partial least squares (PLS, VIP > 1.0) analysis and Spearman’s correlation analysis, 18 (11 bacterial and 7 fungus) were identified as the functional core microbiotas in SPF. Among them, indigenous Saccharomyces, Hanseniaspora, Rhodotorula, Leuconostoc, and Lactobacillus play an important role in the formation of volatile compounds and are worthy of further study, while Escherichia-Shigella, Ralstonia and Zoogloea should be inhibited during the fermentation process. However, a key problem in SPF was the fermentation time, which was too long (about 27 days) and did not meet the needs of industrial production. Overall, the results showed the possibility of considering select indigenous aroma-producing microorganisms as persimmon wine fermentation starters to improve the unique characteristics of persimmon wine.

Shaanxi Opera is one of the oldest dramas of the Han nationality in China, and it is also included in the National Non-Material Cultural Heritage List. As a local culture, it is distinctive in the language features, and its lyrics are written in rhyme with the same number of characters in each line, which has strong value in translation research. Guided by conceptual metaphor theory, this paper analyzes the English translation of metaphor in the script of Women Generals of the Yangs from the aspects of structural metaphor, azimuth metaphor and ontological metaphor, in order to provide some reference and enlightenment for the translation of metaphor in Shaanxi Opera.

The Faraday laser, with Faraday anomalous dispersion optical filter (FADOF) as frequency-selection element, is a natural narrow-bandwidth light source for laser physic experiments. In this work, a dual-frequency (DF) Faraday laser is demonstrated for the first time on Cs D2 line at 852 nm. The frequencies of the two modes of DF Faraday laser hinge on the peak transition frequencies of 852 nm FADOF transmittance spectrum corresponding to the ground state $F=4$ and $F=3$ . The frequency difference between the two modes is tunable over a range of 1.4 GHz with the temperature of Cs vapor cell inside the FADOF. The linewidth of each laser mode is less than 33 kHz. Furthermore, the most probable linewidth of the beat-note spectra between the two modes is 902.95 Hz at different vapor-cell temperatures. Such a DF Faraday laser has many potential applications in atomic physics, such as sub-Doppler spectroscopy and coherent population trapping atomic clocks.

Changes in the oenological parameters, total phenols, total flavonoids, and individual phenols of persimmon during spontaneous and inoculated fermentation were investigated. The volatile compounds and sensory character of the persimmon wine were compared and evaluated simultaneously. Results show that at the end of fermentation, spontaneous persimmon wine (SPW) has higher contents of total flavonoids, total phenols yet lower concentrations of alcohol and volatile compounds than inoculated persimmon wine (IPW). Catechin, salicylic acid, quercetin, and vanillic acid were the main phenolic compounds in both types of persimmon wine. There are six volatile components in the IPW with an OAV greater than 1, which are isoamyl acetate, ethyl hexanoate, methyl octanoate, ethyl octanoate, phenethyl acetate, and 2, 4‐di‐tert‐butylphenol, and these compounds contribute to the IPW with brandy and fruity sensory properties, while only three volatile components in SPW have OAV greater than 1, which are isoamyl acetate, ethyl hexanoate, and ethyl octanoate. Spontaneous fermentation increased the proportion of esters and alcohols in the overall volatile compounds. During sensory evaluation, IPW was characterized by “brandy,” “bitterness,” and low “sweetness,” and SPW has a high score of “sweetness,” “balance,” desirable “color,” and “body.”, Changes in the oenological parameters, total phenols, total flavonoids, and individual phenolic compounds of persimmon wine during spontaneous and inoculated fermentation were investigated. The volatile compounds and sensory character of the persimmon wines were compared and evaluated simultaneously.

The main objective of this study was to isolate newly indigenous yeast strains from the fermentation of jujube liquor. 19 isolated yeast strains were obtained by spontaneous solid-state fermentation and flavour characteristics of the fermented jujube juice were also compared from above selected strains. 3 strains (JM-3, JM-13, JM-17) were screened out and identified as Saccharomyces cerevisiae (S. cerevisiae) by molecular identification. Tolerance tests for glucose, temperature, pH and alcohol of three yeast stains were compared. The result showed that the glucose tolerance of JM-3 was better those of JM-13 and JM-17, the temperature and pH tolerance were similarities in three yeast strains and the alcohol tolerance of JM-13 was better those of JM-3 and JM-17. Jujube juice was used as medium for single and mixed-culture fermentation with commercial S. cerevisiae G-1. All the important aroma compounds were detected in jujube juice fermented with JM-13+G-1 and JM-13 had an excellent potential starter for jujube liquor production.

We propose a method to improve relative laser power stability using a passive photosensitive sunglass lens, which is a commercially available off-the-shelf product. We present a theoretical analysis and identify factors that affect the optimal working state of the lens. A relative laser power stability of 3.3 × 10−5 at 1 s is experimentally achieved, which is more than three times that of 1.2 × 10−4 at 1 s, acquired without power stabilization. This method does not require any active driving device, thereby significantly reducing the complexity and cost of the system, making it suitable for broad applications.

We have proposed a new scheme to realize the Rb optical clock using a pulse-modulated broad-spectrum multi-frequency laser. By applying a pulse-modulated signal to a 420 nm external cavity diode laser, a broad-spectrum comb-tooth laser with multiple frequency components is generated, which can interact with almost all the Rb atoms with different transverse velocities, so that more Rb atoms in the Rb cell can contribute to the frequency stabilization signal of the clock transition spectral line. The effective atomic number is expected to be improved by a factor of 102 - 103, which will significantly improve the signal-to-noise ratio of spectrum, so as to optimize the frequency stability of Rb optical clock. The Rb optical frequency standard with high stability can be widely used in laser physics and precision measurement.

We measure the light shift of the rubidium atomic clock under interaction of a 780 nm laser, which has potential application in the laser power stabilization. At the same time, in order to improve the performance of rubidium clock, we demonstrate a Faraday laser of which the cavity mode is locked to the peak of the transition spectrum, thus suppressing the otherwise existed power and frequency noise caused by the cavity mode fluctuations. This Faraday laser is suitable for the optical pumped rubidium atomic clock with the frequency being stably on resonance with the rubidium 780nm transition, and has potential applications on the cesium beam clocks and fountain clocks.

Two feasible schemes are proposed by laser cooling of alkali atoms to realize the narrow-linewidth, continual superradiant lasing. Utilizing the D1 gray molasses to realize a cloud of cold Cs atoms for the two-level Faraday active optical clock (AOC), the effect of Doppler broadening on the transmission bandwidth of Faraday atomic filter will be effectively suppressed to the level of natural linewidth. Thus, the influence of mechanical or thermal vibrations of cavity mirrors on the clock laser will be decreased by about 102 times, which is expected to further narrow the laser linewidth by two orders of magnitude compared with the thermal atomic Faraday AOC to Hz level. Moreover, the four-level AOC based on the narrow linewidth cooling of Cs atoms using the 6S-7P transition is proposed. The 455 nm laser at 6S 1/2 -7P 3/2 transition plays two roles simultaneously, one is the cooling laser for a magneto-optical trap (MOT), another is the pumping laser for population inversion of 1470 nm clock transition, which is helpful to improve the compactness of the system. In the four-level structure, the frequency of pumping laser is far detuning from that of clock laser, therefore, the light shift resulting from the 455 nm laser is negligible. This four-level AOC based on cold atoms will further reduce the collision shift in thermal atom system to achieve a high-precision optical frequency reference.

This paper provides a feasible method to narrow the linewidth of the laser by modulation transfer spectroscopy, benefiting from a high feedback bandwidth and the high signal-to-noise ratio of the spectroscopy. We experimentally stabilize the frequency of a 420 nm blue diode laser with a free-running Lorentz linewidth of 43 kHz on the quantum transition of 85Rb, and the heterodyne experiments based on two identical configurations showing that the linewidth of laser is efficiently narrowed by 6 times, namely a Lorentz linewidth of 7 kHz. With the feedback bandwidth and signal-to-noise ratio in-loop further enhanced, the scheme with a relatively simple construction can potentially achieve a sub-kHz laser linewidth.

We demonstrate a Faraday laser at Cs-D2 resonance line 852 nm using a Cs Faraday optical filter as frequency-selecting element. In contrast to typical diode laser with high stability of the emission frequency by additional control systems, our Faraday laser offers stable output frequency exactly set by the peak transmission frequency of the Cs 852 nm Faraday optical filter. The system works stably over a range of laser diode (LD) current from 60 to 130 mA and the LD temperature from 14 to 35 $$^{\circ }$$∘C, as well as the 48-h wavelength fluctuation range of no more than ± 2 p.m. A most probable linewidth of 17 kHz with Lorentz fitting is obtained by beating between two identical laser systems. The wavelength of our system is stabilized within transmission frequency region of 852 nm Faraday optical filter, and the peak of the transmission is corresponding to Cs atomic Doppler broadened line at the cell temperature of 41 $$^{\circ }$$∘C and the magnetic field of 330 G, making it suitable for laser-pumped Cs gas-cell and atomic beam frequency standard, etc. Moreover, this scheme is firstly used on Cs atom, opening new doors in research of Faraday laser and its applications.

In this paper, a wireless optical communication system based on Faraday anomalous dispersion optical filter (FADOF) is proposed to supress the ambient light. Experimental results show that the Q factor of 20Mbit/s OFDM-QPSK signal can be improved by 9 dB after filtering the ambient light by using the FADOF.

Background Respiratory syncytial virus (RSV) is the most common viral cause of pediatric bronchiolitis and pneumonia worldwide. Risk factors for high mortality and prolonged morbidity after RSV infection include premature birth, bronchopulmonary dysplasia, congenital heart disease, and Down syndrome. However, some previously healthy, full-term children who are infected with RSV also require hospitalization and even experience severe sequelae or death. Case presentation In this report, we present the case of an RSV-associated death of a child who was born at full-term and developed normally up to the age of 2 years old. Cardiopulmonary arrest occurred within 3 days after the onset of symptoms, which included cough and high fever. Complete brain edema was prominent, and encephalopathy was developing. Viral antigen detection and microbiome analyses of oral swab and nasopharyngeal aspirate specimens verified an RSV infection, while bacterial culture of blood specimens yielded negative results. The RSV strain detected in this patient was subtyped as RSVB9, and no mutation was found in the six antigenic sites for targeted drugs or vaccines. Conclusions The patient had a severe infection associated with RSV, which was very likely the cause of her central nervous system infection and acute neurological complications.

A poor papillary thyroid cancer (PTC) prognosis is strongly associated with the BRAF V600E mutation. During tumor progression, levels of the high mobility group box 1 (HMGB1) protein are often dysregulated. Results herein demonstrate that HMGB1 protein levels differ between tumor and adjacent non-tumor tissue and that HMGB1 mRNA levels were higher in wild-type BRAF PTC tissues than in BRAF V600E PTC tissues (2-△Ct 0.31 ± 0.25 vs. 0.16 ± 0.12; P