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Four commercial greases with various thickeners and base oils were experimentally examined to compare their false brinelling wear resistance in a test rig simulating roller bearings during rail/sea transportation for the first time. Greases containing zinc dialkyl dithiophosphates (ZDDP) showed superior false brinelling reduction, evidenced by no visible wear mark in the raceways. The mechanism for false brinelling mitigation was shown to be from a ZDDP-induced tribofilm which decreases the friction and wear coefficient in the contact area. Surface chemical analysis showed that for grease lubricated fretting contacts, ZDDP-derived tribofilms can be generated in the presence of micro-sliding motions and energy dissipation at the contact interface at low frequency (i.e., 4–8 Hz), due to the mechanochemical reactions. For greases without ZDDP, false brinelling wear was reduced by 97% when using grease with a more abundant and less viscous oil, which bleeds readily from an open structured thickener. The results highlight the ability of ZDDP as an additive in grease to better protect roller bearings against false brinelling during rail/sea transportation. [ABSTRACT FROM AUTHOR]

Objectives: To assess and compare the stability and outcomes of the two surgical approaches for patients with roll asymmetry. Materials and methods: A total of 50 adult patients were consecutively recruited for this prospective study. Patients with class III asymmetry and lip or occlusal cant who underwent bimaxillary surgery were grouped according to surgical approach: asymmetric posterior impaction on both sides (API, n = 31) and posterior impaction on one side and posterior extrusion on the other side (PIE, n = 19). Postsurgical stability and outcomes between groups were determined with cone-beam computed tomography for facial midline, lip, and occlusal cant at 1 week (T1), and at least 12-month postsurgery (T2, completion of orthodontic treatment). Results: Presurgery, the upper anterior occlusal cant and lip cant were significantly greater for the PIE group (p < 0.05). Postsurgery (T2), the mandible moved upward and rotated upward in both groups. However, the upward rotation was significantly greater in the PIE group compared with the API group. Although the two approaches resulted in significant improvements in facial symmetry, the deviation in the facial midline remained under-corrected for most API patients. Conclusions: Patient outcomes for mandibular stability and facial symmetry differed between the two surgical approaches for correction of class III asymmetry with lip or occlusal cant. Clinical relevance: The findings of this study suggest that planned over-correction is a reasonable option for the approach of asymmetric posterior impaction on both sides. [ABSTRACT FROM AUTHOR]

This study presents a novel and non-destructive method for quantitatively analysing grease lubricated bearing wear by using X-ray microcomputed tomography (μCT). The efficacy of μCT to measure rolling contact wear via wear debris analysis was demonstrated, as was quantifying grease contamination and wear debris identification. Test rig experiments of grease lubricated spherical roller bearings, were performed to simulate rolling contact wear. Six grease samples were collected from two bearings at three different intervals to investigate wear progression. Results showed μCT measured wear volume increased exponentially with increasing bearing operation times. Grease cleanliness (particle counts per ml) worsened nonlinearly due to the exponential growth of wear debris over longer bearing operational times. Comparing the conventional ISO281 bearing assembly and operating condition assessment, a particle-count based method via μCT analysis provided a less subjective and dynamic assessment for quantifying grease contamination. Grease contamination was found to increase with longer operational timeframes due to the combination of wear debris growth and decreased lubrication film thickness. Finally, laminar, chunk and spherical wear particles, associated with rolling contact wear, were identified by the morphometric parameters measured by μCT. This study highlights the potential of μCT as a wear monitoring and grease quality assessment technique for railway bearing applications. • Microcomputed tomography is pioneered to measure wear in test rig bearings. • The proposed method is nondestructive and requires no sample manipulation. • The efficacy in wear measurement is proven through debris analysis in grease. • Quantitative analysis of 3D wear debris images provides wear mechanism assessment. • Grease contamination worsens with wear debris growth exponentially and lubricant film thinning. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel water-based lubricants were developed by integrating zeolites with SDBS. • Synergetic interactions between additives led to improved lubrication performance. • The combination of 4A zeolite + SDBS led to improved lubricity and high wear. • 13X zeolite + SDBS combination resulted in marked reduction in friction and wear. • Lubricated micro-bearing effect due to SDBS attached on 13X particles was proposed. Water-based lubricants are a low-cost and environmentally-friendly alternative to their oil-based counterparts. Developing novel water-based formulations with improved lubricity is the key to broadening their industrial applications. We report herein two new water-based hybrid lubricants that integrate sodium dodecylbenzene sulfonate (SDBS) with 4A and 13X zeolites respectively. Their tribological performance was assessed using a block-on-ring test. The addition of SDBS mitigated stick–slip motion, leading to the reduction of coefficient of friction (COF), but caused chemical erosion of the steel surface. The addition of zeolite into water led to an increase in COF due to the occurrence of three-body abrasion. The combination of SDBS and zeolite brought about unique and superior lubrication performance attributed to the synergetic interactions between them. The application of 4A + SDBS lubricant led to a 10% reduction in COF and a four-fold increase in material removal compared to water. The angular 4A particles augmented material removal in combination with the corrosive effect of SDBS. The use of 13X + SDBS lubricant, on the other hand, resulted in a 60% reduction in COF and a 94% decrease in wear comparing to water. This can be ascribed to the "lubricated micro-bearing" effect as a result of SDBS attachment on the rounded 13X particles. [ABSTRACT FROM AUTHOR]

This work characterises wear debris/particles generated naturally in grease-lubricated spherical roller bearings (SRBs) used in urban rolling stock. Morphological examination revealed the most active wear in grease lubricated SRBs is predominantly associated with the rolling/sliding contact and adhesive mechanisms, resulting in chunk, laminar and spherical wear debris found most frequently. Morphological transitions in spherical and chunky wear debris associated with bearings' service life was seen for the first time in railway SRBs. Interestingly, the formation of chunky wear debris was not necessarily governed by rolling contact fatigue and crack propagation mechanisms seen in oil lubricated systems, but rather associated with the collapse of larger spherical wear debris. Additionally, the surface complexity observed on individual debris, associated with rolling-sliding wear is also discussed. The findings add to the sparse knowledge of wear debris formation and their contribution to grease degradation, particularly for railway SRBs. Furthermore, an estimate of the contamination level of the SRBs was obtained by carefully adapting the fluid lubricant standards. The combination of these results will allow for improved wear prediction and the optimisation of bearing maintenance practices. • Seven types of wear debris naturally generated in grease lubricated rolling stock SRBs was identified and studied. • Formation of wear debris in the railway SRBs is mostly associated with rolling/sliding contact mechanism. • Morphological evolution of spherical debris linked with service life was seen for the first time in grease lubricated SRBs. • Chunk wear debris found in grease lubricated SRBs were governed by collapse and/or fracture of large spherical wear debris. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a widely used dye and photodynamic therapy (PDT) agent that can produce reactive oxygen species (ROS) after light exposure, triggering apoptosis. However, it is hard for the dye to penetrate through the cell membrane, leading to poor cellular uptake; thus, drug carriers, which could enhance the cellular uptake, are a suitable solution. In addition, the defective vessels resulting from fast vessel outgrowth leads to an enhanced permeability and retention (EPR) effect, which gives nanoscale drug carriers a promising potential. In this study, we applied poly(12-(methacryloyloxy)dodecyl phosphorylcholine), a zwitterionic polymer-lipid, to self-assemble into liposomes and encapsulate MB (MB-liposome). Its properties of high stability and fast intracellular uptake were confirmed, and the higher in vitro ROS generation ability of MB-liposomes than that of free MB was also verified. For in vivo tests, we examined the toxicity in mice via tail vein injection. With the features found, MB-liposome has the potential of being an effective PDT nano agent for cancer therapy. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Microalloying with Be effectively improved the oxidation resistance of Mg-2Zn, Mg-2Sn, AS21 and ZC63. • Microalloying with Be had little effect on the oxidation resistance of ZK20, AM60 and Mg-2Y. • The oxidation resistance of Mg alloys was closely related to the mechanical strength of the initially formed oxide layers. • The nanoindentation testing provides a new approach to understand the mechanism for the oxidation resistance of Mg alloys. Abstract The present work studied how Be influences Mg alloy oxidation. Be microalloying significantly decreased the oxidation rate at 500 °C and increased the ignition temperatures of as-cast Mg-2Zn, Mg-2Sn, AS21, and ZC63. However, Be addition had little effect on the oxidation resistance of as-cast ZK20, AM60 and Mg-2Y. Based on the nanoindentation results, the present results can be well understood and explained using the recently proposed oxide layer reinforcement model, which indicates that the mechanical strength of the initially formed oxide controls Mg alloy oxidation. [ABSTRACT FROM AUTHOR]

The oxidation resistance of Mg-9Al-1Zn alloy (AZ91) was significantly improved through microalloying with 60 ppm Be. Be reinforced the initially formed oxide layer on the alloy surface by (i) the formation of a (Mg,Be)O solid solution due to the Be enrichment; and (ii) the refined gains of the (Mg,Be)O. During high-temperature oxidation, the reinforced (Mg,Be)O layer provided sufficient strength to withstand the internal stresses and the Mg vaporisation, and therefore delayed the oxide layer cracking and debonding from the substrate. In addition, the initial oxidation rates of AZ91 and Be-containing AZ91 were closely related to surface roughness. [ABSTRACT FROM AUTHOR]

In this study, we first analyze the usability of recycling products, and use the fuzzy set method to determine the main impact on recycling items and their corresponding weights by using the Analytic Hierarchy Process (AHP) to identify various impact recycling levels. The Group Decision Supporting System (GDSS) determines the test standards for the recycling rating. It provides a convenient way for recyclers or manufacturers to classify their own products and use fuzzy numbers to select a set of test standards. It can deduce the recovery rate and remanufacturing rate of different recycling processing levels through the Markov chain model to find out the inventory model and total cost. In the numerical analysis, we found that a recycling rate of more than 90% is probably a necessary decision. Since the processing cost of the 100% recovery rate is doubled, the inventory level and total cost will increase with it. Therefore, this study was combined with the reverse logistics method to find the appropriate decision-making strategy and plan, such as the optimal inventory level and recovery rate. [ABSTRACT FROM AUTHOR]

This study develops an integrated supplier–remanufacturer and customer (downstream manufacturer) inventory model that takes into account three-echelon system with correlated demands and remanufacturing products allowing a backorder goods condition. This paper improves the observable fact that the first model system customer might select two sources from remanufactured products or supplier products without defective items. The second model further considers the defective items during the screening duration. The results are examined analytically and numerically to show that the policy of single shipment in large lot sizes results in less total cost than a frequent shipments policy. We also explore the impact of recovery rate on the economic benefits of the inventory system. In addition, we also perform sensitivity analysis to study the impact of seven important parameters (transportation cost, recovery rate, screening rate, annual demand, defect rate, and backorder rate, holding cost,) on the optimal solution. Management insights were also discussed. [ABSTRACT FROM AUTHOR]