The growth year of ginseng is very important as it affects its economic value and even defines if ginseng can be used as medicine or food. In the case of large-scale developments in the ginseng industry, a set of non-destructive, fast, and nonprofessional operations related to the growth year identification method is needed. The characteristics of ginseng reflectance spectral data were analyzed, and the growth year recognition model was constructed by a decision-tree-based random forest machine learning method. After independent verification, the accuracy of distinguishing ginseng food and medicine can reach 92.9%, with 6-year growth as the boundary, and 100%, with 5-year growth as the boundary. The research results show that the spectral change of ginseng is the most obvious in the fifth year, which provides a reference for the key research years based on chemical analyses and other methods. For the application of growth year recognition, the NIR band (1000–2500 nm) had little contribution to the recognition of ginseng growth years, and the band with the largest contribution was 400–650 nm. The recognition model based on machine learning provides a non-destructive, fast, and simple scheme with high accuracy for ginseng year recognition, and the spectral importance analysis conclusion of ginseng growth years provides a design reference for the development of special lightweight spectral equipment for year recognition.
In this study, a new tungsten-based ceramic alloy (TCA) is obtained using liquid-phase sintering during the preparation of traditional 95 W alloys. In this process, sintered Al2O3 ceramic microspheres with a purity of 99%, a mass fraction of 1% ~ 5%, and the particle size of 60 ~ 120 μm are added. This new material's microstructure, mechanical properties, fracture mechanism, and high-speed penetration performance are studied. Results show that the TCA's tensile strength, ductility, and impact toughness decrease with the addition of Al2O3 ceramic. However, when 3 wt% Al2O3 ceramic is added, the TCA spherical fragment exhibits the best high-speed impact property against the 616 rolled homogeneous armor plate (22SiMn2TiB) of 15 mm thick. Therefore, TCA can be used as the material of the kinetic energy damage element to improve its high-speed penetration ability.
The elevated temperature fatigue strength and room temperature tensile properties and fatigue strength of cast Ti-47Al-2Cr-2Nb-0.15B(atomic fraction, %) alloy after thermal exposure were investigated. The microstructural change of the bulk alloy and the microstructure of surface layer after 650 ℃/100 h and 800 ℃/100 h exposures were analyzed by means of XRD and SEM. The room temperature tensile ductility and fatigue strength decreased slowly with increasing exposure temperature when it is below 650 ℃, and then rapidly decreased above this temperature. Dependence of fatigue strength for the unexposed alloy with test temperature exhibits the same trend. The surface layer formed after 650 ℃/100 h exposure is an oxygen-enriched layer, while that after 800 ℃/100 h exposure is an oxide layer consisting of TiO2 and Al2O3. Such a change in the nature of the surface layer corresponds to the onset of rapid drop in mechanical proerties and fatigue strength of the alloy with increasing exposure temperature.
Objective: Postoperative sleep disturbance after surgery is not conducive to the recovery of patients. The purpose of this study was to determine the influence of the timing of surgery (morning vs afternoon) on the postoperative sleep quality of elderly patients and to analyze the relationship between the timing of surgery and the change in the melatonin level. Methods: Sixty patients who received hip surgery were randomly assigned to the Morning Group (Group M) or the Afternoon Group (Group A). The sleep quality was assessed by the Richards–Campbell Sleep Questionnaire. Before and after surgery, the nocturnal urine was collected over a 12-h period, and the 6-sulfatoxymelatonin concentration was measured. Also, the incidence of postoperative delirium (POD) was observed. Results: On the first and second nights after surgery, the sleep quality scores of the patients in Group A were greater than those in Group M, and there was no difference in the sleep quality scores between the two groups on the third night after surgery ( P =0.000, P =0.002, P > 0.05, respectively). In addition, the urine 6-sulphatoxymelatonin concentration was found to be greater in Group A than in Group M on the first night of surgery ( P =0.00). Both the postoperative sleep quality scores and urine 6-sulphatoxymelatonin concentration were significantly less than those before surgery ( P =0.00, P =0.00). Conclusion: The postoperative sleep quality scores and melatonin levels of elderly patients who received hip surgery under general anesthesia were significantly less than those of the patients before surgery. Furthermore, the short-term sleep quality of the patients who received surgery in the afternoon was better than that of the patients who received surgery in the morning. This difference may be related to the short-term change of the melatonin level after surgery. Keywords: sleep quality, melatonin, timing of surgery
Titanium alloys are often used to make deep-sea pressure hulls and the creep strain produced in use is not negligible. The variation of dislocation structures with room temperature creep stresses in equiaxed α grains of Ti-6Al-4V ELI alloy were examined using transmission electron microscope. The plastic deformation mechanism varied with the applied stress, mainly manifested by the change of dislocation patterns and the sequential activation of slip systems. At the stress below the creep threshold, even though almost no macroscopic creep was generated, a small number of immobile dislocations and dislocation networks occurred in the sample. The networks were composed of dislocations with different Burgers vectors, and part of them would evolve into low angle grain boundaries (LAGBs). At the stresses above the threshold, the density of dislocations in α grains increased with the stress level, and the basal , pyramidal and slips were activated successively which also contributed to creep and participated in the formation of LAGBs. Prismatic slip was always the predominant creep deformation mechanism for the studied stress range. The activation of difficult slip systems was analyzed to be due to the stress concentration and stress redistribution between soft and hard phases/grains. In general, the amount of LAGBs increased with the applied creep stress, but the LAGBs formed by dislocation networks decreased.
Dexmedetomidine has been reported to improve postoperative sleep quality. However, the underlying mechanism remains unclear. This study aimed to investigate the effect of intraoperative dexmedetomidine infusion on postoperative sleep quality and changes in melatonin secretion in older patients undergoing elective thoracoscopic lung surgery. A total of 126 older patients were randomly divided into two groups: dexmedetomidine group (Group D), which received continuous dexmedetomidine infusion at 0.3-0.5 µg/(kg·h) combined with propofol during surgery, and propofol group (Group P), which received propofol alone. The primary outcome was the postoperative sleep quality on the first postoperative night, assessed by the Richards-Campbell Sleep Questionnaire (RCSQ). Secondary outcomes included sleep quality scores on the second and third postoperative nights, melatonin concentrations postoperatively, and the incidence of delirium on the first and seventh postoperative days (discharge day). On the first postoperative night, Group D had a higher sleep quality score compared to Group P (57±11.4 vs 53±10.3; [95% CI, 1.1 to 8.7];P = 0.012), with no difference between the groups on the second and third postoperative nights. There was no statistically significant difference in the preoperative and postoperative night 3 urine 6-SMT concentrations between the two groups (P > 0.05); however, Group D had significantly higher urine 6-SMT concentrations on postoperative nights 1 and 2 compared to Group P (27 (24, 30) vs 21 (17, 24); [95% CI, -8.56 to -4.73]; P = 0.000. 28 (25, 30) vs 26 (21, 27); [95% CI, -4.37 to -1.65]; P = 0.000). There was no significant difference in the incidence of postoperative delirium between the two groups (P=0.65). Continuous intraoperative infusion of dexmedetomidine can effectively improve sleep quality during the first postoperative night by promoting melatonin secretion over the first two postoperative nights.
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