Elastohydrodynamic Analysis of Spur Gears Using Load-Sharing Concept: Running-In and Steady-State

Gears are widely used in industry and hence their performance is of vital importance. Under the typical operating conditions of gears, the lubricant layer formed between the teeth of the pinion and the gear cannot completely separate the surfaces and contact of asperities of the pinion and gear occurs. This case is usually referred to as mixed lubrication problem. In this research the load-sharing concept has been employed to predict the performance of the pinion-gear system. The load-sharing concept is an efficient method to solve the mixed lubrication problem and is capable to predict the thickness of the lubricant film, contribution of the fluid film and asperities in carrying the load, friction coefficient, lubricant temperature, and wear with fairly good accuracy. During the initial stage of contact, a considerable number of plastic contact occurs between asperities resulting in permanent change of surface roughness profile. This period which is called running-in has a significant effect on the steady-state performance of the pinion-gear system. The developed model has the capability to predict the variation of surface roughness and contribution of fluid film as well as asperities in carrying the load during running-in. The steady-state wear of gears is predicted using the thermal desorption model. A test rig is designed and built which is capable to mimic the operating condition of any point on the involute profile of gear. Two motors are used to rotate the rollers to generate the same rolling and sliding speed as the corresponding point of the involute profile of pinion-gear system. A hydraulic system is used to exert the desired load on the rollers and keep them in contact under the applied load. The sensors that are mounted on this test rig monitor the speed of each shaft, applied load, surface temperature, and wear depth. The results of the experiments that are conducted on the fresh rollers as well as broken-in roller are shown to be in good agreement with the predicted running-in behavior and steady-state behavior, respectively

Comparison of prospective and retrospective memory in addicted men, have left addicts, and healthy individuals

زمینه و هدف: اعتیاد یک بیماری جسمی، روانی، اجتماعی و معنوی است و یکی از آسیب های جدی به دنبال سوء مصرف مواد، آسیب مغزی است. هدف اصلی پژوهش حاضر مقایسه حافظه آینده نگر و گذشته نگر در مردان معتاد، معتاد ترک کرده و سالم بود. روش بررسی: در این مطالعه توصیفی- تحلیلی (مقطعی) تعداد 35 نفر معتاد، 32 نفر معتاد ترک کرده و 35 نفر غیر معتاد، به طور هدفمند انتخاب شدند. برای گردآوری داده ها از پرسشنامه حافظه گذشته نگر و آینده نگر استفاده گردید. برای تحلیل آماری از آزمون تحلیل واریانس چند متغیره (مانوا) و آزمون تعقیبی توکی استفاده شد. یافته ها: نتایج پژوهش نشان داد که بین معتادان، معتادان ترک کرده و افراد سالم در عملکرد حافظه آینده نگر تفاوت معنی داری وجود دارد (05/0>P)؛ اما در عملکرد حافظه گذشته نگر تفاوت معنی داری وجود ندارد؛ همچنین نتایج آزمون تعقیبی توکی نشان داد که میانگین حافظه آینده نگر در معتادان بیشتر از معتادان ترک کرده و افراد عادی است (05/0>P). نتیجه گیری: بنابراین افزایش طول مدت اعتیاد باعث تخریب بیشتر حافظه آینده نگر شده و در نتیجه ترک اعتیاد را مشکل تر می سازد

GIS multi-criteria analysis by orderedweighted averaging (OWA): Toward an integrated citrus management strategy

This study proposes a site location assessment model for citrus cropland using multi-criteria evaluation (MCE) and the combination of a set of factors for suitability mapping and delineating the suitable areas for citrus production in Ramsar, Iran. It defines an incorporated method for the suitability mapping of the most appropriate sites for citrus cultivars with an emphasis on the multi-criteria decision analysis (MCDA) process. The combination of geographic information system (GIS) and a modified version of the analytic hierarchy process (AHP) based on the ordered weighted averaging (OWA) technique is also emphasized. The OWA is based on two principles, namely: the weights of relative criterion significance and the order weights. Therefore, the participatory technique was employed to outline the set of standards and the important criterion. The results derived from the GIS-OWA technique indicate that the cultivation of citrus is feasible only in limited areas, which make up 6.7% of the total area near the Caspian Sea. This investigation has shown that the GIS-OWA model can be integrated into MCDA to select the optimal site for citrus production. The present research highlights how multi-criteria in GIS can play a considerable role in decision making for evaluating the suitability of selected sites for citrus production

25-Hydroxy Vitamin D Level and Its Correlation with Mean Platelet Volume in Preeclampsia

Background: Preeclampsia is one of the challenging complications of pregnancy, of which little is known about its etiology and pathogenesis. Many studies have shown higher mean platelet volume (MPV) in preeclamptic patients. Vitamin D deficiency is in association with larger-size platelets. Thus, we aimed to determine the correlation of vitamin D with MPV in preeclamptic patients. Methods: This prospective case–control study was conducted in two tertiary hospitals in Tehran, Iran. Overall, 85 preeclamptic pregnant women and 85 normotensive pregnant women were entered between 2017 and 2018. Serum vitamin D concentration (ng/ml) and MPV (femtoliter) were measured for all patients. Results: MPV was significantly higher in the cases compared to controls (10.59±1.08 vs 8.10±0.95, P=0.0001). In addition, serum vitamin D level in the preeclamptic group was significantly lower in compare to the control group (17.79±11.03 vs 30.24±12.49; P=0.0001). In multivariate logistic regression analysis, high age of mother (OR: 1.13; 95% CI: 1.01-1.27; P=0.03), low level of serum vitamin D (OR: 0.93; 95% CI: 0.87-0.99; P=0.02) and high MPV (OR: 8.83; 95% CI: 4.17-18.67; P=0.0001) were independent predictors of preeclampsia. Moreover, a correlation analysis revealed that vitamin D levels correlated negatively with MPV (r= -0.41, P<0.0001). Conclusion: Low levels of vitamin D in preeclamptic pregnancy are associated with higher platelet activity and thrombosis. In fact, the increment of MPV level might be a potential pathway for adverse outcomes of pregnancy including preeclampsia in the context of vitamin D deficiency.

The Trail Pheromone of the Venomous Samsum Ant, Pachycondyla sennaarensis

Ant species use branching networks of pheromone trails for orientation between nest and resources. The current study demonstrated that workers of the venomous samsum ant, Pachycondyla sennaarensis (Mayr) (Hymenoptera: Formicidae: Ponerinae), employ recruitment trail pheromones discharged from the Dufour's gland. Secretions of other abdomen complex glands, as well as hindgut gland secretions, did not evoke trail following. The optimum concentration of trail pheromone was found to be 0.1 gland equivalent/40 cm trail. This concentration demonstrated effective longevity for about one hour. This study also showed that P. sennaarensis and Tapinoma simrothi each respond to the trail pheromones of the other species as well as their own

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

Global, regional, and national incidence of six major immune-mediated inflammatory diseases: findings from the global burden of disease study 2019

Background The causes for immune-mediated inflammatory diseases (IMIDs) are diverse and the incidence trends of IMIDs from specific causes are rarely studied. The study aims to investigate the pattern and trend of IMIDs from 1990 to 2019. Methods We collected detailed information on six major causes of IMIDs, including asthma, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, psoriasis, and atopic dermatitis, between 1990 and 2019, derived from the Global Burden of Disease study in 2019. The average annual percent change (AAPC) in number of incidents and age standardized incidence rate (ASR) on IMIDs, by sex, age, region, and causes, were calculated to quantify the temporal trends. Findings In 2019, rheumatoid arthritis, atopic dermatitis, asthma, multiple sclerosis, psoriasis, inflammatory bowel disease accounted 1.59%, 36.17%, 54.71%, 0.09%, 6.84%, 0.60% of overall new IMIDs cases, respectively. The ASR of IMIDs showed substantial regional and global variation with the highest in High SDI region, High-income North America, and United States of America. Throughout human lifespan, the age distribution of incident cases from six IMIDs was quite different. Globally, incident cases of IMIDs increased with an AAPC of 0.68 and the ASR decreased with an AAPC of −0.34 from 1990 to 2019. The incident cases increased across six IMIDs, the ASR of rheumatoid arthritis increased (0.21, 95% CI 0.18, 0.25), while the ASR of asthma (AAPC = −0.41), inflammatory bowel disease (AAPC = −0.72), multiple sclerosis (AAPC = −0.26), psoriasis (AAPC = −0.77), and atopic dermatitis (AAPC = −0.15) decreased. The ASR of overall and six individual IMID increased with SDI at regional and global level. Countries with higher ASR in 1990 experienced a more rapid decrease in ASR. Interpretation The incidence patterns of IMIDs varied considerably across the world. Innovative prevention and integrative management strategy are urgently needed to mitigate the increasing ASR of rheumatoid arthritis and upsurging new cases of other five IMIDs, respectively. Funding The Global Burden of Disease Study is funded by the Bill and Melinda Gates Foundation. The project funded by Scientific Research Fund of Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital (2022QN38)

Application of Load-Sharing Concept to Mechanical Seals

Mechanical seals are mechanisms that are used to prevent fluid leakage. Since the seal surfaces are in contact with one another, hydrodynamic and contact forces are functions of surface roughness. Additionally, since the lubrication regime under specific operating conditions such as low speed or high load causes the seal to operate in the mixed lubrication regime, thus the contact of asperities plays an important role. The primary purpose of this paper is to apply the load-sharing concept to study the behavior of a mechanical seal in a mixed lubrication regime. The predicted results are compared to the published data from the literature, showing acceptable accuracy. The model presented in this paper can predict the performance of the mechanical seal system in a short execution time while providing acceptable accuracy by considering the surface roughness effect