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Gear is one of the most crucial components of the transmission system, and the performance of gear directly affects the efficiency and reliability of the transmission system. Conventional methods for designing gear parameters involve several time-consuming and complex steps, which may not guarantee optimal performance. Therefore, we propose a new method for designing gear parameters that aims to improve efficiency and accuracy. First, the tooth surface equations of spur and helical involute gears suitable for symmetric and asymmetric teeth are deduced based on the gear-forming machining principle. Second, the performance evaluation models for load capacity, dynamic performance, efficiency, and power density of the gears are established based on the precise gear surface. The design objectives are standardized and evaluated comprehensively using a linear weighting method. Finally, a forward performance-driven design method of gear parameters is established. The proposed method is applied to a helical gear pair design case, and the results show that 90.7% of the individuals in the Pareto optimal front are asymmetric gears, with 9.3% being symmetric gears. This suggests that asymmetric gears have more opportunities to be optimal than symmetric gears. The highest-ranked gear designed using the proposed method is superior to the gear designed using conventional methods. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Objective Methods Results Conclusion Skin aging is characterized by an imbalance between the generation and degradation of extracellular matrix molecules (ECM). Matrix metalloproteinases (MMPs) are the primary enzymes responsible for ECM breakdown. Intrinsic and extrinsic stimuli can induce different MMPs. However, there is limited literature especially on the summary of skin MMPs and potential inhibitors.We aim to focus on the upregulation of MMP expression or activity in skin cells following exposure to UV radiation. We also would like to offer valuable insights into potential clinical applications of MMP inhibitors for mitigating skin aging.This article presents the summary of prior research, which involved an extensive literature search across diverse academic databases including Web of Science and PubMed.Our findings offer a comprehensive insight into the effects of MMPs on skin aging after UV irradiation, including their substrate preferences and distinct roles in this process. Additionally, a comprehensive list of natural plant and animal extracts, proteins, polypeptides, amino acids, as well as natural and synthetic compounds that serve as inhibitors for MMPs is compiled.Skin aging is a complex process influenced by environmental factors and MMPs. Research focuses on UV‐induced skin damage and the formation of Advanced Glycosylation End Products (AGEs), leading to wrinkles and impaired functionality. Inhibiting MMPs is crucial for maintaining youthful skin. Natural sources of MMP inhibitor substances, such as extracts from plants and animals, offer a safer approach to obtain inhibitors through dietary supplements. Studying isolated active ingredients can contribute to developing targeted MMP inhibitors. [ABSTRACT FROM AUTHOR]

Early Holocene populations in southern China and Southeast Asia are generally considered to have continued practising hunting and gathering, while millet and rice cultivation developed to the north and east. Dingsishan, the oldest Holocene open-air site in South-east Asia, however, had yet to provide direct evidence for human health and subsistence strategies. The authors present isotopic and demographic analyses of Dingsishan individuals from 9000-7000 BP, indicating that the inhabitants relied on freshwater resources, particularly in the third period (r. 7000 BP). Comparison with contemporaneous farming populations also reveals a seemingly higher average life expectancy for the fisher-hunter-gatherers at Dingsishan. Keywords: southern China, Dingsishan, Neolithic, stable isotope analysis, subsistence strategy, human health, Introduction Since the Last Glacial Maximum (LGM), global temperatures have risen and rainfall has increased, creating favourable ecological conditions for the domestication of plants and animals. Between c. 11 000 [...]

Inhibitory control, as an essential cognitive ability, affects the development of higher cognitive functions. Rhythmic perceptual stimulation has been used to improve cognitive abilities. It is unclear, however, whether it can be used to improve inhibitory control. This study used the Go/NoGo task and the Stroop task to assess various levels of inhibitory control using rhythmic audio-visual stimuli as the stimulus mode. Sixty subjects were randomly divided into three groups to receive 6 Hz, 10 Hz, and white noise stimulation for 30 min. Two tasks were completed by each subject both before and after the stimulus. Before and after the task, closed-eye resting EEG data were collected. The results showed no differences in behavioral and EEG measures of the Go/NoGo task among the three groups. While both 6 Hz and 10 Hz audio-visual stimulation reduced the conflict effect in the Stroop task, only 6 Hz audio-visual stimulation improved the amplitude of the N2 component and decreased the conflict score. Although rhythmic audio-visual stimulation did not enhance response inhibition, it improved conflict inhibition. [ABSTRACT FROM AUTHOR]

Many cases of artificial soft clay foundation constructed by hydraulic filling and improved by the vacuum preloading show the clogging phenomenon in the surrounding soil, which compromises the improvement quality. To clarify the clogging mechanism and the formation of soil columns, the vacuum process was tracked from macro to micro by laboratory model tests. Results show that the soil column with higher strength (density) and lower water content was formed surrounding the prefabricated vertical drainage (PVD). Mercury intrusion porosimetry (MIP) tests revealed that the pore-entrance diameter of the soil column after 50 and 43 days of vacuum application ranged from 100 to 600 nm, and that at peak it is 300 nm. However, the mean diameter of the colloidal particles in tail water decreases from 1000 to 100 nm with continuous vacuum application, and then becomes stable at about 100 nm after 43 days. After re-visiting the vacuum process of the hydraulic reclamation mud, the pore-size distribution of surrounding soils and particle-size distribution of the tail water, the clogging was explained by the filling of the pores of the soil column by the colloidal particles in pore water. This mechanism differentiates the artificial foundation improved by vacuum preloading from the natural foundation for the presence of rich colloidal particles in pore water. Key words: vacuum preloading, hydraulic reclamation mud, clogging of soil column, colloid property of tail water, pore-entrance size distribution. De nombreux cas de fondations en argile molle artificielle construites par remplissage hydraulique et ameliorees par la precharge sous vide montrent le phenomene de colmatage dans le sol environnant, qui compromet la qualite de l'amelioration. Pour clarifier le mecanisme de colmatage et la formation des colonnes de sol, le processus de vide a ete suivi de macro a micro par des tests de modele de laboratoire. Les resultats montrent que la colonne de sol avec une plus grande resistance (densite) et une plus faible teneur en eau a ete formee autour du drainage vertical prefabrique (<< PVD >>). Les tests de porosimetrie au mercure (<< MIP >>) ont revele que le diametre d'entree des pores de la colonne de sol apres 50 et 43 jours de vide variait de 100 a 600 nm et que le pic atteignait 300 nm. Cependant, le diametre moyen des particules colloidales dans l'eau d'aval diminue de 1000 a 100 nm avec une application continue sous vide, puis devient stable a environ 100 nm apres 43 jours. Apres avoir revu le processus de vide de la boue de recuperation hydraulique, la distribution de la taille des pores des sols environnants et la distribution granulometrique de l'eau d'aval, le colmatage a ete explique par le remplissage des pores de la colonne de sol par les particules colloidales dans l'eau interstitielle. Ce mecanisme differencie la fondation artificielle amelioree par le prechargement sous vide de la fondation naturelle pour la presence de particules colloidales riches dans l'eau interstitielle. Mots-cless: precharge sous vide, boue de recuperation hydraulique, colmatage de la colonne de sol, propriete colloidale de l'eau d'aval, distribution de la taille de l'entree des pores., Introduction With the rapid development of Chinese coastal cities and the increase in population, the land resources are becoming more and more scarce, making marine reclamation very important. Haihua (also [...]

Elevated and increasing NO3− ${{\text{NO}}_{3}}^{-}$ concentration in groundwater affect groundwater supplies in China and elsewhere. However, how groundwater flow affects NO3− ${{\text{NO}}_{3}}^{-}$ concentration in groundwater has yet to be fully understood. Herein, multi‐isotopes (15N, 11B, 18O, and 2H) and local indicators of spatial association (LISA) were used to elucidate the spatiotemporal variation, sources, and patterns of NO3− ${{\text{NO}}_{3}}^{-}$ and its response to groundwater flow in Poyang Lake Basin where agriculture, industry and urban coexist. The location of NO3− ${{\text{NO}}_{3}}^{-}$ hotspots identified by LISA tended to move from the middle to lower reaches of Ganfu Plain with groundwater flow, and hotspots area expanded in the upper reaches of Xin River Basin and northwest of the study area during the transition from dry season to wet season. Our results revealed that variations of regional NO3− ${{\text{NO}}_{3}}^{-}$ concentration were controlled by groundwater recharge or flow mode (vertical or lateral), biogeochemical processes and sources (sewage and manure). In some areas with the single stratigraphic structure (unconfined aquifer), spatiotemporal variation of NO3− ${{\text{NO}}_{3}}^{-}$ concentration was influenced by local pollution sources and vertical recharge of current precipitation (vertical flow). In some areas with binary structures (confined aquifer), groundwater was mainly recharged by lateral flow and NO3− ${{\text{NO}}_{3}}^{-}$ concentration was mainly affected by mixing effect of upstream groundwater, reflecting human activities in the upper reaches rather than local human activities. In lakeside floodplain, groundwater NO3− ${{\text{NO}}_{3}}^{-}$ was attenuated by the dissimilatory NO3− ${{\text{NO}}_{3}}^{-}$ reduction to NH4+ ${{\text{NH}}_{4}}^{+}$. This study provides a novel insight into groundwater flow controlling on spatiotemporal distribution of NO3− ${{\text{NO}}_{3}}^{-}$ concentration in the regional scale. Key Points: Regional‐seasonal changes of hotspots and cool spots of nitrate concentration were identified by local indicators of spatial associationNitrate hotspots showed a seasonal shift along flow or expansion dominated by groundwater recharge mode linked with aquifer heterogeneityWe developed a conceptual model of spatiotemporal variation in regional nitrate content that describes the crucial role of groundwater flow [ABSTRACT FROM AUTHOR]