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In order to investigate the intrinsic relationship between protein characteristics and quality changes during the hot air drying of shrimp, Penaeus vannamei was dried by hot air at 55 ℃ after being boiled in 3% salt solution for 2 minutes. We studied changes in the microstructure and quality of shrimp, and systematically investigated changes in the oxidative degradation degree, intramolecular valence bonds, and secondary and tertiary structure of protein. The results showed that the drying treatment gradually decreased the L*, a* and b* values of shrimp, and changed the texture characteristics, and the hardness, adhesiveness and chewiness were increased to 344.78 N, 45.01 mJ and 116.50 mJ at the end of drying, respectively. In addition, oxidative denaturation and degradation of proteins occurred; the total sulfhydryl content decreased to 0.36 μmol/g at the end of drying, while the carbonyl content increased to 2.03 nmol/mg protein, and the trichloroacetic acid (TCA)-soluble peptide content increased to 0.91 μmol/g. The protein structure was significantly changed; the relative contents of ionic and hydrogen bonds decreased, the relative contents of hydrophobic and disulfide bonds increased, the secondary structure was transformed from α-helix to β-fold, β-turn and random coil, the intensity of tryptophan fluorescence decreased, and the tertiary structure was also changed. Pearson correlation analysis showed that the color changes were mainly related to protein oxidation and protein degradation and denaturation significantly affected the textural properties of shrimp. This study can provide theoretical support for further improving the quality of dried shrimp products.

In this study, we experimentally showcase the microfiber evanescent-field photothermal gas detection by exploiting all-fiber MHz-level frequency shift scheme. Based on the acousto-optic interaction effect, the low-frequency shifts of 0.9 MHz and 1.83 MHz can be obtained through the cyclic conversion between the transverse core modes LP01 and LP11 in the few-mode fiber. Our proposed all-fiber frequency shifters show flexible MHz-level up(down) frequency shifts with superior sideband rejection ratio (over 40 dB) and low insertion loss (less than 1 dB). Furthermore, an all-fiber heterodyne interferometric detection system is implemented by leveraging the above low-frequency shifters, in which around 1-μm-diameter microfiber is investigated for photothermal gas detection. A pump-probe configuration is employed to obtain the photothermal effect induced by the gas absorption of the modulated evanescent field. By demodulating the phase of the beat signal output by the interferometer, an equivalent detection limit (1σ) of 32 ppm and a response time of 22 s are achieved for ammonia, as well as 0.24 % instability within 48 pump cycles. Given its compact all-fiber configuration and high sensitivity with fast response, the experimental results can pave the way for widespread applications like heterodyne detection, fiber optical sensors, and interplanetary coherent communications.

The major bioactive components and flavor characteristics of Toona sinensis buds from different production areas such as Sichuan, Shaanxi, Shandong, Shanxi, Hebei and Yunnan were explored. The overall odor was evaluated by sensory evaluation, and the volatile components were analyzed using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) in order to analyze the differences in the flavor characteristics of T. sinensis buds from different production areas. The sensory evaluation results showed that the odor of T. sinensis buds from Yunnan was rich and pleasant, while the odor of T. sinensis buds from Shaanxi was irritating. The results of electronic nose analysis showed that the contents of aromatics and long-chain alkanes in T. sinensis buds from the six production areas were similar, while the contents of nitrogen oxides and sulfides were quite different. A total of 76 volatile substances were identified by GC-IMS, including 12 alcohols, 10 esters, 9 pyrazines, 9 ketones, 8 terpenoids, 7 organic sulfides, 7 aldehydes, 6 acids, 4 phenols and 4 other compounds. The principal component analysis (PCA) of electronic nose and GC-IMS data showed that the flavor of T. sinensis buds from Yunnan was unique, and the flavors of T. sinensis buds from Sichuan, Shaanxi and Shandong were similar. T. sinensis buds from Shanxi was different from those from other geographical origins, and the content of flavor substances in T. sinensis buds from Hebei was low. The results of this study may provide a theoretical basis for the screening of T. sinensis for deep processing.

Abstract In early spring or winter, supercooled raindrops impact on transmission lines and accumulate ice on its surface frequently, which may induce galloping vibration occurs. Studies on collision coefficient or icing mostly focus on key parameters of wind velocities, raindrop sizes and conductor diameters, whereas few involve electric field. In order to clarify the influence of the direct current electric field on the collision coefficient of transmission lines, a calculation formula of the mass flow rate of raindrops was proposed, and the process of raindrops hitting the conductor surface is numerically calculated by the Euler–Lagrange method. The effects of electric field intensity, conductor diameter, cross‐sectional shape, wind velocity, raindrop diameter and charge density on the collision coefficient of transmission lines are analyzed. The results show that the collision coefficient decreases with the increase of electric intensity. As the electric intensity increases from 0 to 66.7 kV/cm, the collision coefficient decreases about 33%. Because of the repulsion between the conductor and raindrops, more raindrops move away from the conductor surface and collision coefficient decreases. The collision coefficient of the actual conductor under no electric field is slightly smaller than that of the simplified circular cross‐section. Under DC electric field, the collision coefficient of the conductor decreases with wind velocity increase up to 8 m/s. Beyond that threshold, the collision coefficient is almost constant.

Background The prevalence of neurodevelopmental disorders in premature infants is high, and there is an urgent need to improve neurodevelopmental outcomes of them. There are few reports on amplitude-integrated electroencephalography (aEEG) -assessed effect of multisensory (MS) interventions on brain function of premature infants by aEEG. Objective To evaluate the effect of MS interventions on improving brain function of premature infants. Methods A single-center, randomized controlled trial was conducted. One hundred and twenty-six premature infants who were admitted to Department of Pediatrics, the First Affiliated Hospital of Guangxi Medical University from October 2020 to September 2021 were selected and randomly divided into control group (n=63) and intervention group (n=63) by random numbers according Excel. Both groups received routine treatment and nursing care, the intervention group additionally received MS interventions developed by our team (including auditory, tactile, visual and vestibular interventions) , twice a day, 15 minutes each time. The time of intervention lasted for at least 7 days for both groups. Before and 7 days after the intervention, the lower boundary voltage, bandwidth, and aEEG score during the quiet sleep (QS) period and active sleep (AS) period, average time and total time of QS period were monitored by AEEG. The Neonatal Behavioral Neurological Assessment (NBNA) was used to evaluate the neurobehavior. The Gesell Developmental Schedules (GDS) was used to evaluate the development quotient at the corrected age of one month. Results 119 premature infants completed the study, including 59 cases in the control group and 60 cases in the intervention group. Seven days after intervention, intervention group had higher lower boundary voltage〔 (5.47±0.92) μV vs (5.10±0.87) μV〕and narrower bandwidth〔 (18.90±1.90) μV vs (19.78±2.50) μV〕 during QS period than the control group (P0.05) . Moreover, intervention group had longer average time of QS period 〔 (25.67±6.95) min vs (23.29±4.87) min〕 and longer total time of QS period 〔 (62.80±18.89) min vs (55.27±20.65) min〕 than control group (P< 0.05) . Intervention group also had higher total score of NBNA 〔 (34.82±2.97) vs (33.12±3.49) 〕 (P< 0.05) . At the corrected age of one month, intervention group had higher developmental quotient scores in terms of gross motor 〔 (52.83±10.93) vs (48.83±10.11) 〕, fine motor〔 (51.67±11.05) vs (47.71±9.15) 〕, adaptive development 〔 (55.28±11.65) vs (50.31±10.14) 〕, language 〔 (53.40±11.29) vs (49.41±9.82) 〕 and personal-social〔 (53.57±10.57) vs (49.51±9.35) 〕 than the control group (P