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Preventive maintenance is an indispensable part of civil aircraft operational support activities,and it is also the basis for ensuring the safe and economic operation of civil aircraft.As the first international general standard for preventive maintenance,S4000P provides preventive maintenance with a reasonable analysis method for the for-mulation of initial maintenance tasks throughout the life cycle,the analysis of unplanned maintenance tasks,and the optimization of initial maintenance tasks through operating data.In this paper the research status of preventive maintenance is combed,the S4000P standard is analyzed,and the analysis framework of civil aircraft preventive maintenance is established based on S4000P,which provides strong support for promoting the formulation and optimization process of civil aircraft preventive maintenance.

PurposeFor patients with symptomatic middle cerebral artery (MCA) atherosclerotic stenosis, identifying the potential stroke mechanisms may contribute to secondary prevention. The purpose of the study is to explore the relationship between stroke mechanisms and the characteristics of culprit plaques in patients with atherosclerotic ischemic stroke in the M1 segment of the middle cerebral artery (MCA) based on high-resolution vessel wall imaging (HR-VWI).MethodsWe recruited 61 patients with acute ischemic stroke due to MCA atherosclerotic stenosis from Shenzhen Bao'an District People's Hospital. According to prespecified criteria based on infarct topography and magnetic resonance angiography, possible stroke mechanisms were divided into parent artery atherosclerosis occluding penetrating artery (P), artery-to-artery embolism (A), hypoperfusion (H), and mixed mechanisms (M). The correlation between the characteristics of MCA M1 culprit plaque and different stroke mechanisms was analyzed using HR-VWI. The indicators included plaque surface irregularity, T1 hyperintensity, location, plaque burden (PB), remodeling index (RI), enhancement rate, and stenosis rate.ResultsParental artery atherosclerosis occluding penetrating artery was the most common mechanism (37.7%). The proposed criteria showed substantial to excellent interrater reproducibility (κ, 0.728; 0.593–0.863). Compared with the P group, the surface irregularity, T1 hyperintensity, and obvious enhancement of the culprit plaque in the A group were more common (p < 0.0125). Compared with the other stroke mechanisms, positive remodeling of culprit plaques was more common (p < 0.0125), the RI was greater (p < 0.05), and the PB was the smallest (p < 0.05) in the P group. The enhancement ratio (ER) was smaller in the P group (p < 0.05). Compared with the A group, T1 hyperintensity of the culprit plaque was more common in the H group (p < 0.0125), and the stenosis rate was greater (p < 0.05). After adjustment for clinical demographic factors in the binary logistic regression analysis, the enhancement level (odds ratio [OR] 0.213, 95% CI (0.05–0.91), p = 0.037) and PB of culprit plaque (OR 0, 95% CI (0–0.477), p = 0.034) were negatively associated with P groups.ConclusionThe culprit plaque characteristics of patients with symptomatic MCA atherosclerotic in different stroke mechanisms may be evaluated using HR-VWI. The plaque characteristics of different stroke mechanisms may have clinical value for the selection of treatment strategies and prevention of stroke recurrence.Clinical trial registrationIdentifier: ChiCTR1900028533.

The slow light effect at the band gap edge of photonic nanocrystals (PhCs) can improve the light utilization efficiency of photocatalysts by enhancing light collection. This study reported an anatase inverse opal TiO2 (IO TiO2) with a 3D closely packed face-centered cubic structure prepared using a PhC template. The simulation of the electric field modulus distribution in the inverse opal structure was performed, and the enhancement of photocatalytic efficiency caused by the slow light effect at the red and blue edges of the photonic band gap was analyzed. The experimental results of rhodamine B degradation agreed with the simulation. IO TiO2 has a high specific surface area (91 m2/g), which is 4.33 times that of powder TiO2, and also has high pore volumes (0.13 cm3/g). In addition, it facilitates the separation of photogenerated carriers due to the existence of large pores that are periodically interconnected, thus, significantly improving photocatalytic efficiency. The apparent rate constant of IO TiO2 is 9.96 × 10–3 min–1, which is 1.81 times that of powder TiO2. The blue edge of 200 nm IO TiO2 is spectrally closer to the electronic band gap of TiO2. Also, it presents optimal photodegradation efficiency (70.02%), and its rate constant is 2.13 times higher than porous block TiO2 without a band gap. Moreover, a detailed path of a possible reaction mechanism is proposed based on the results of the free radical trapping experiment and EPR analysis. This research offered opportunities for a deeper understanding and more efficient utilization of the blue-edge slow light effect. The slow light can be leveraged to enhance the optical nonlinear effect, which has practical significance for solar energy collection and conversion, optical switches, and photocatalysis. [ABSTRACT FROM AUTHOR]

Concrete expanding-plate piles (CEP piles) represent a novel type of variable cross-section concrete cast-in-place pile, wherein one or more bearing plates are added to the pile body to enhance its load-bearing capacity. Compared to traditional uniform-diameter uplift piles, the bearing plates of CEP uplift piles provide additional resistance against uplift, substantially increasing the pile's uplift bearing capacity. CEP piles exhibit a wide range of application potential in structures such as high-rise buildings, cable-stayed bridges, and offshore platforms. However, due to changes in the load-bearing mechanism, the pile–soil interaction of CEP piles significantly differs from that of straight-shaft piles. Theories applicable to the group effect of straight-shaft piles cannot be directly applied to CEP piles, which has led to imperfections in the theoretical framework for designing CEP piles in practical engineering applications, hindering their broader adoption. Therefore, this paper employs a finite element simulation analysis to study the failure modes of three groups of symmetrically arranged CEP pile groups. The effects of pile spacing on the uplift bearing capacity of CEP pile groups are investigated, leading to a revision of the formula for calculating the uplift bearing capacity of CEP pile groups. This study enhances the theoretical understanding of the load-bearing behavior of CEP pile groups, providing a theoretical basis for their practical engineering applications. [ABSTRACT FROM AUTHOR]

Piglets, especially weaning piglets, show a lower level of immunity and higher morbidity and mortality, owing to their rapid growth, physiological immaturity, and gradual reduction of maternal antibodies, which seriously affects their growth and thus, value. It is important that piglets adapt to nutrient digestion and absorption and develop sound intestinal function and colonization with gut microbiota as soon as possible during their early life stage. Lactoferrin is a natural glycoprotein polypeptide that is part of the transferrin family. It is widely found in mucosal secretions such as saliva and tears, and most highly in milk and colostrum. As a multifunctional bioactive protein and a recommended food additive, lactoferrin is a potential alternative therapy to antibiotics and health promoting additive for piglet nutrition and development. It is expected that lactoferrin, as a natural food additive, could play an important role in maintaining pig health and development. This review examines the following known beneficial effects of lactoferrin: improves the digestion and capacity for absorption in the intestinal tract; promotes the absorption of iron and reduces the incidence of iron deficiency anemia; regulates intestinal function and helps to balance the microbial biota; and enhances the resistance to disease of the piglets via modulating and enhancing the immune system. Key words: lactoferrin, piglets, iron deficiency, intestinal tract, immune response. Les porcelets, en particulier les porcelets sevres, en raison de leur croissance rapide, de leur immaturite physiologique et la reduction graduelle des anticorps maternels, montrent un niveau d'immunite plus faible et une morbidite et une mortalite plus elevees, ce qui affecte serieusement la performance de l'elevage et les benefices economiques. Il est important que les porcelets s'adaptent a la digestion et a l'absorption de nutriments et qu'ils developpent le plus tot possible leur fonction intestinale et la colonisation du microbiote intestinal au cours des premiers stades de leur croissance. La lactoferrine est une glycoproteine naturelle qui se differencie de la famille des transferrines. Elle est en grande partie presente dans les secretions muqueuses telles que la salive et les larmes, et plus encore, dans le lait et le colostrum. En tant que proteine bioactive multifonctionnelle et qu'additif alimentaire recommande, la lactoferrine est un candidat potentiel comme solution de rechange aux antibiotiques et comme additif favorisant la sante, dans la nutrition et la production des porcelets ; on s'attend a ce que la lactoferrine, en tant qu'additif vert, puisse jouer un role important dans le maintien de la sante en production porcine. Les effets actuels suivants sont ici passes en revue et evalues : l'amelioration de la capacite de digestion et d'absorption dans le tractus intestinal, la promotion de la supplementation en fer et la reduction de l'incidence de l'anemie ferriprive, la regulation de la fonction intestinale et de l'equilibre de la flore microbienne, et le renforcement de la resistance aux maladies des porcelets par la lactoferrine en tant qu'agent immunomodulateur et stimulateur. Mots-cles : lactoferrine, porcelets, carence en fer, tractus intestinal, reponse immunitaire., Introduction The piglet stage is a vital stage of pig growth and production because this is the period of fastest growth and metabolism, the rapid development of digestive organs, and [...]

Objective: To judge the efficacies of neural stem cell (NSC) transplantation on functional recovery following contusion spinal cord injuries (SCIs). Data sources: Studies in which NSCs were transplanted into a clinically relevant, standardized rat model of contusion SCI were identified by searching the PubMed, Embase and Cochrane databases, and the extracted data were analyzed by Stata 14.0. Data selection: Inclusion criteria were that NSCs were used in in vivo animal studies to treat contusion SCIs and that behavioral assessment of locomotor functional recovery was performed using the Basso, Beattie, and Bresnahan lo-comotor rating scale. Exclusion criteria included a follow-up of less than 4 weeks and the lack of control groups. Outcome measures: The restoration of motor function was assessed by the Basso, Beattie, and Bresnahan locomotor rating scale. Results: We identified 1756 non-duplicated papers by searching the aforementioned electronic databases, and 30 full-text articles met the inclusion criteria. A total of 37 studies reported in the 30 articles were included in the meta-analysis. The meta-analysis results showed that transplanted NSCs could improve the motor function recovery of rats following contusion SCIs, to a moderate extent (pooled standardized mean difference (SMD) = 0.73; 95% confidence interval (CI): 0.47–1.00; P < 0.001). NSCs obtained from different donor species (rat: SMD = 0.74; 95% CI: 0.36–1.13; human: SMD = 0.78; 95% CI: 0.31–1.25), at different donor ages (fetal: SMD = 0.67; 95% CI: 0.43–0.92; adult: SMD = 0.86; 95% CI: 0.50–1.22) and from different origins (brain-derived: SMD = 0.59; 95% CI: 0.27–0.91; spinal cord-derived: SMD = 0.51; 95% CI: 0.22–0.79) had similar efficacies on improved functional recovery; however, adult induced pluripotent stem cell-derived NSCs showed no significant efficacies. Furthermore, the use of higher doses of transplanted NSCs or the administration of immunosuppressive agents did not promote better locomotor function recovery (SMD = 0.45; 95% CI: 0.21–0.70). However, shorter periods between the contusion induction and the NSC transplantation showed slightly higher efficacies (acute: SMD = 1.22; 95% CI: 0.81–1.63; subacute: SMD = 0.75; 95% CI: 0.42–1.09). For chronic injuries, NSC implantation did not significantly improve functional recovery (SMD = 0.25; 95% CI: –0.16 to 0.65). Conclusion: NSC transplantation alone appears to be a positive yet limited method for the treatment of contusion SCIs.

Pile spacing is an important factor affecting the bearing capacity of concrete expansion pile (CEP) groups. In this study, a pile group was simulated and analyzed using ANSYS software R19.0. The influence of pile spacing on the bearing capacity of the pile group under a vertical load was determined using three sets of four-, six-, and nine-pile models with different pile spacings. The grid division of the pile soil model adopts a mapping method, using the contact types of rigid and flexible bodies and applying surface loads to the model piles step-by-step. After vertical pressure was applied to the model pile, in-depth analysis was conducted on the displacement cloud map, pile top displacement, and other data. The different stress conditions of corner, edge, and center piles in each model group were compared and analyzed, revealing the relationship between the stress mechanism and failure law of the soil around the pile and the pile spacing. It was found that the soil displacement range of edge piles is slightly larger than that of corner piles. This phenomenon gradually decreases with increasing pile spacing. When the pile spacing increases to four times the cantilever diameter, the difference in soil displacement at different pile positions is small, and the pile spacing has little effect on the compressive bearing capacity of the pile group. Thus, it is reasonable to control the pile spacing at three to four times the cantilever diameter. In the nine-pile model, when the load is loaded to the 20-step level, the displacement value of the central pile is −72.278 mm, while the displacement values of the edge pile and corner pile are −69.012 mm and −66.806 mm. It is shown that increasing the pile spacing can effectively reduce the pile group effect and improve the bearing capacity of the pile foundation. At present, CEP pile groups are gradually being applied in practical engineering, but research on the influence of pile spacing on the compressive bearing performance of CEP pile groups is still at a very early stage. This article reinforces the influence of pile spacing on the compressive bearing performance of CEP pile groups. It provides theoretical support for its application in practical engineering. [ABSTRACT FROM AUTHOR]