Artículos de revistas: "Lubricant Formulation"

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Kittipongpatana, Ornanong S., Karnkamol Trisopon, Phanphen Wattanaarsakit y Nisit Kittipongpatana. "Utilization and Evaluation of Rice Bran and Rice Bran Wax as a Tablet Lubricant". Pharmaceutics 16, n.º 3 (20 de marzo de 2024): 428. http://dx.doi.org/10.3390/pharmaceutics16030428.

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The rice bran and rice bran wax of the KJ CMU107 rice strain were investigated as potential tablet lubricants in a directly compressed tablet formulation. Stabilized full-fatted rice bran (sFFRB), stabilized defatted rice bran (sDFRB), and rice bran wax (RBW) extracted and purified from crude rice bran oil (cRBO) were tested. Two commercial lubricants, including magnesium stearate (MGS) and hydrogenated cottonseed oil (HVO), were employed as the standards in the formulated mixtures, which contained spray-dried rice starch (SDRS) as a diluent. The tableting was carried out for each formulation, and the obtained tablets were physically and mechanically evaluated. Among the parameters investigated were the general appearance, ejection force, weight variation, hardness, friability, and disintegration time. The powder flow was also determined for each formulation. The results showed that the tablet ejection forces for all the lubricated formulations (58–259 N) were significantly lower than that of the non-lubricated control formulation (349 N). The use of sFFRB as a lubricant at 0.5–2.0% w/w could lower the ejection force up to 78%, but the hardness reduced so drastically that the formulations failed the friability test due to the chipping of the tablets’ edges. Moreover, sDFRB performed significantly better as the use at 0.5–1.0% w/w in the formulation helped to lower the ejection forces by up to 80% while maintaining the changes in the tablet hardness within 10%. RBW functioned effectively as a tablet lubricant at a concentration of 0.5% w/w, yielding tablets with good strength comparable to standard HVO lubricant while helping to reduce the ejection force by 82%. In formulations with good lubrication, i.e., friability < 1%, the powder flow was improved, and the tablet disintegration times were within the same range as the control and HVO formulations. In conclusion, sDFRB displayed a lubricant property at concentrations between 0.5 and 1.0% w/w, with slightly negative effects on the tablet hardness. RBW from KJ CMU107 rice was an effective tablet lubricant at 0.5% w/w, with no effect on tablet hardness. Both materials can be further developed for use as commercial lubricants in direct compression.

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Asgarirad, H., S. Honary, P. Ebrahimi y M. Ruhi. "The Effect of Different Lubricant Mixture and the Method of Preparation on Properties of Effervescent Tablets". Advanced Materials Research 129-131 (agosto de 2010): 1252–56. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.1252.

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Various mixtures of different lubricants and preparation methods were investigated in order to find the best lubricant mixture for effervescent tablets. Methods: Lubrication effectiveness in two methods of granulation of standard effervescent formulation was tested by using mixtures of various percents of different lubricants. L- Leucine, Polyethylen glycol 6000 and SLS were used as lubricant. The hardness, disintegration time and abrasion for tablets which produced from each formulation were determined. All formulations were investigated for transparency and tastelessness after their complete disintegration of tablets in 200 ml of water. Results: The results show the best lubrication results were obtained by using a mixture of 2% w/w of L- Leucine and 3% w/w of PEG 6000 by ethanol granulation method.

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Muhamad Azwar Azhari, Nor Hasrul Akhmal Ngadiman, Noordin Mohd Yusof, Ani Idris y Norazlianie Sazali. "Feasibility Studies of Treated Used Cooking Palm Oil as Precursor for Bio-Lubricant". Journal of Advanced Research in Applied Mechanics 111, n.º 1 (24 de noviembre de 2023): 30–37. http://dx.doi.org/10.37934/aram.111.1.3037.

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The non-renewability and and non-biodegradability of petroleum based lubricants as well as the environmental impacts their waste contributes to the environment has caused the search for a substitute for precursor of lubricant formulation. The food security issue has caused major concerns on how vegetable oil could replace petroleum based product lubricants. This paper reports the feasibility studies of kinematic viscosity, friction and wear properties of treated used cooking palm oil as precursor for development of new bio-lubricant. The treated used cooking palm oil displayed a comparable value of kinematic viscosity of 43.6cSt, coefficient of friction of 0.126 and 122µm which is almost similar to the value of fresh cooking palm oil. Treated used cooking palm oil is seen to be a suitable candidate for precursor of bio-lubricant formulation, However, some additives may need to be added as to increase the tribological properties for treated used cooking oil to be used as a bio-lubricant.

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Muhamad Azwar Azhari, Nor Hasrul Akhmal Ngadiman, Noordin Mohd Yusof, Ani Idris y Norazlianie Sazali. "Influence of Molybdenum Disulphide (MoS2) Nanoparticles Loading in Treated Used Palm Oil Bio-lubricant on Surface Roughness during Turning of AISI420". Journal of Advanced Research in Micro and Nano Engieering 14, n.º 1 (22 de marzo de 2024): 1–7. http://dx.doi.org/10.37934/armne.14.1.17.

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The environmental impact and non-biodegradability of petroleum-based lubricants has caused some researchers to shift the formulation of lubricant formulation using plant-based oil, However, food security has caused concerns in development of new bio-lubricants. In this study, treated used cooking palm oil added with Zinc Dialkyldithiophosphate and Molybdenum Disulphide nanoparticles were used as lubricant to assist the cutting of hardened martensitic stainless steel AISI420 using coated carbide tool. Surface roughness of the cut workpiece was investigated using a surface roughness tester. From the study, treated used cooking oil added with ZDDP and 0.8wt% MoS2 nanoparticles displayed the lowest average surface roughness of workpiece with Ra = 0.532µm and total roughness Rz = 4.006µm. This concluded that the new formulated bio-lubricant can successfully replace the readily available commercial cutting fluid as it produces a low surface roughness during cutting process.

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5

Chandran Suja, Vineeth. "Challenges in Mitigating Lubricant Foaming". Lubricants 10, n.º 6 (1 de junio de 2022): 108. http://dx.doi.org/10.3390/lubricants10060108.

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Lubricant foaming and its mitigation is an active area of research driven by demands from modern machinery that require foam-free lubricant operation over extended periods and under adverse conditions. Tackling lubricant foaming has proven to be challenging due to interdependent foam stabilization mechanisms and a multitude of antifoam inactivation routes. This perspective briefly outlines the key challenges faced by researchers in this field. Overcoming these challenges to create lubricants with superior foaming characteristics requires the development of new lubricant and antifoam chemistry as well as a shift from the existing trial-and-error methods to mechanistic-insight-driven lubricant formulation and antifoam design.

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Schüler, Fabian, Malgorzata Holynska, Théo Henry, Michael Buttery, Katrin Meier-Kirchner y Christian Göhringer. "Development of a Space Grease Lubricant with Long-Term-Storage Properties". Lubricants 12, n.º 3 (24 de febrero de 2024): 72. http://dx.doi.org/10.3390/lubricants12030072.

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Controlled vacuum environments as in space applications represent a challenge for the lubrication of tribological components. In addition to common space lubricant requirements like, e.g., low evaporation, a broad operational temperature range and a high stability during operation, long-term-storage (LTS) properties have gained increasing attention recently. The term addresses the time-dependent stability of a lubricant under static conditions, which can mean chemical degradation processes such as oxidation on the one hand, but also the physical separation of oil and thickener in heterogeneous lubricants like greases. Due to the extended storage periods of lubricated components on-ground but also during a space mission for several years, it has to be ensured that a lubricant is still functional after LTS. This article depicts the development of a space lubricant grease with LTS properties. Firstly, LTS requirements and methods for their assessment are discussed. In the following, a systematic approach towards the design of a grease formulation compatible with LTS is described. Finally, the manufacturing of prototype formulations and their broad characterization by means of LTS behaviour, outgassing, and tribological performance is presented.

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7

Costa, Henara Lillian, Tiago Cousseau y Roberto Martins Souza. "Current Knowledge on Friction, Lubrication, and Wear of Ethanol-Fuelled Engines—A Review". Lubricants 11, n.º 7 (12 de julio de 2023): 292. http://dx.doi.org/10.3390/lubricants11070292.

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The urgent need for drastic reduction in emissions due to global warming demands a radical energy transition in transportation. The role of biofuels is fundamental to bridging the current situation towards a clean and sustainable future. In passenger cars, the use of ethanol fuel reduces gas emissions (CO2 and other harmful gases), but can bring tribological challenges to the engine. This review addresses the current state-of-the-art on the effects of ethanol fuel on friction, lubrication, and wear in car engines, and identifies knowledge gaps and trends in lubricants for ethanol-fuelled engines. This review shows that ethanol affects friction and wear in many ways, for example, by reducing lubricant viscosity, which on the one hand can reduce shear losses under full film lubrication, but on the other can increase asperity contact under mixed lubrication. Therefore, ethanol can either reduce or increase engine friction depending on the driving conditions, engine temperature, amount of diluted ethanol in the lubricant, lubricant type, etc. Ethanol increases corrosion and affects tribocorrosion, with significant effects on engine wear. Moreover, ethanol strongly interacts with the lubricant’s additives, affecting friction and wear under boundary lubrication conditions. Regarding the anti-wear additive ZDDP, ethanol leads to thinner tribofilms with modified chemical structure, in particular shorter phosphates and increased amount of iron sulphides and oxides, thereby reducing their anti-wear protection. Tribofilms formed from Mo-DTC friction modifier are affected as well, compromising the formation of low-friction MoS2 tribofilms; however, ethanol is beneficial for the tribological behaviour of organic friction modifiers. Although the oil industry has implemented small changes in oil formulation to ensure the proper operation of ethanol-fuelled engines, there is a lack of research aiming to optimize lubricant formulation to maximize ethanol-fuelled engine performance. The findings of this review should shed light towards improved oil formulation as well as on the selection of materials and surface engineering techniques to mitigate the most pressing problems.

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8

Dellis, Polychronis. "Squeeze Film Investigations in a Simulating Piston-Ring Cylinder Liner Experimental Set-up". Tribologie und Schmierungstechnik 69, eOnly Sonderausgabe 2 (2022): 4–9. http://dx.doi.org/10.24053/tus-2022-0032.

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The importance of these investigations lies to the combination of experimental results with cavitation initiation investigations and its development after the dead centers of the stroke as well as rheological behavior of different chemical additives with a view to establishing the likely performance gains in new lubricant formulations. Lubricant formulation plays an important role because at higher temperatures lubricant additives have a different interaction with contacting surfaces and in this manner the resulting effect of asperity contact is either increased or reduced.

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Li, Weimin, Cheng Jiang, Nan Xu, Rui Ma y Xiaobo Wang. "Tribological properties of polyol-ester-based lubricants and their influence on oxidation stability". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, n.º 6 (13 de septiembre de 2018): 823–30. http://dx.doi.org/10.1177/1350650118799546.

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Unlike oxidative degradation of lubricants, tribology-induced degradation is rarely studied. In this work, the tribological performance and oxidative stability of ester-based lubricants were evaluated before and after tribological testing. Results showed that the tribological performances of base oils are highly dependent on the lubricant formulation and test conditions. Tribological processes could cause detrimental effects on oxidative stability even under moderate conditions. The addition of antiwear additives seems to effectively inhibit the chemically breakdown of esters by forming a protective film. Mechanical shearing, high temperature in contact zones, catalytic effect of nascent surface, wear debris, as well as self- catalysis are the major reasons that are responsible for the oxidative deterioration of the lubricant after tribological testing.

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Dellis, Polychronis Spyridon. "Piston-ring performance: limitations from cavitation and friction". International Journal of Structural Integrity 10, n.º 3 (10 de junio de 2019): 304–24. http://dx.doi.org/10.1108/ijsi-09-2018-0053.

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Purpose Cavitation in piston-ring lubrication is studied as part of the performance of piston-ring assemblies. Cavitation degrades performance in engineering applications and its effect is that it alters the oil film pressure, generated at the converging-diverging wedge of the interface. Studies tried to shed light to the phenomenon of cavitation and compare it with cavities that have been identified in bearings. The paper aims to discuss this issue. Design/methodology/approach Lubricant formulations were used for parametric study of oil film thickness (OFT) and friction providing the OFT throughout the stroke and LIF for OFT point measurements. Lubricant formulation affects cavitation appearance and behaviour when fully developed. Findings Cavitation affects the ring load carrying capacity. Different forms of cavitation were identified and their shape and size (length and width) is dictated from reciprocating speed and viscosity of the lubricant. A clear picture is given from both techniques and friction results give quantifiable data in terms of the effect in wear and cavitation, depending on the lubricant properties. Research limitations/implications Engine results are limited due to manufacturing difficulties of visualisation windows and oil starvation. Therefore, full stroke length sized windows were not an option and motoring tests were implemented due to materials limitations (adhesive and quartz windows). Lubricant manufacturer has to give data regarding the chemistry of the lubricants. Originality/value The contribution of cavitation in piston-ring lubrication OFT, friction measurements and lubricant parameters that try to shed light to the different forms of cavitation. A link between viscosity, cavitation, shear thinning properties, OFT and friction is given.

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Yahayaa, Muhammad Sharil, Nurliyana Abdul Raof, Zulkifli Ibrahim, Azniza Ahmad y Chandima Gomes. "Modifications Required for Palm Oil to be Qualified as a Mechanical Lubricant". International Journal of Manufacturing, Materials, and Mechanical Engineering 9, n.º 1 (enero de 2019): 50–66. http://dx.doi.org/10.4018/ijmmme.2019010104.

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Adaptation of apt chemical modifications and incorporation of suitable additives, especially, nano-additives, could improve the properties of bio-lubricants derived from palm oil. This makes it one of the best alternatives to mineral oil lubricants. Possible chemical modifications are hydrogenation, esterification/ transesterification, epoxidation and metathesis. Feasible additives and nano-additives available in the market for minimizing the drawbacks of palm oil as a lubricant are ionic liquids, phosphorus, sulphur, zinc dialkyl dithiophosphate, metal, metal oxides, metal sulphides, carbonates, borates, carbon materials, organic materials, hexagonal boron nitride, alumina, CaO, CuO, ZnO, TiO2 and lanthanum borates. Few of them may not be environmental friendly. In line with market potentials and demand, it could be predicted that ROI of funding for the research and development of palm oil as a bio-lubricant may be significantly high. The study addresses tribological performance and properties, chemical modifications and formulation with additives of palm oil as a bio-lubricant.

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12

Hernaiz, Marta, Iker Elexpe, Estíbaliz Aranzabe, Beatriz Fernández, Xana Fernández, Silvia Fernández, Martí Cortada-García y Andrés T. Aguayo. "Study of the Effect of ZnO Functionalization on the Performance of a Fully Formulated Engine Oil". Nanomaterials 13, n.º 18 (11 de septiembre de 2023): 2540. http://dx.doi.org/10.3390/nano13182540.

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The automotive sector is demanding higher specifications to achieve maximum efficiency; in this sense a new generation of lubricants with higher thermo-oxidative stability and superior tribological properties is being explored. The formulation of nanolubricants based on the nature of different nanomaterials is one of the most recent approaches, with several gaps to cover, such as dispersion stability, related to the compatibility of proposed nanomaterials with conventional additives and baseoils used in lubricant formulation. This study evaluated the effect of ZnO nanomaterial dispersed in a commercial engine oil using two different approaches; the use of surfactant and nanomaterial surface functionalization to promote higher stability and lower cluster size. Experimental evidence shows a synergetic effect between the tribological protection mechanism and the antioxidant properties in the lubricant. The effect of nanoparticle cluster size, functionalization level, and nanomaterial content are presented.

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13

Radya A. Bashir* y Eltayeb S. Elamin. "Formulation and Optimization of Stable Aspirin 100mg Tablets". Omdurman Journal of Pharmaceutical Sciences 2, n.º 3 (28 de diciembre de 2022): 247–57. http://dx.doi.org/10.52981/ojps.v2i3.2871.

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Several moisture and temperature-sensitive medicines cannot be manufactured in Sudan due to extreme climatic conditions. Keeping these factors under control during production is difficult task. It is possible to overcome these difficulties by using excipients and utilizing technology in the production of the drug. This study aimed to adjust and improve the formulation of aspirin using different excipients and different technological approaches to produce stable aspirin tablets. Microcrystalline cellulose and lactose were used as fillers and stearic acid as a lubricant, four aspirin formulations, two formulations containing lactose and two formulations containing microcrystalline cellulose were prepared for aspirin 100 mg. For each formulation, wet granulation and direct compression techniques were applied separately, to study the effect of manufacturing technology and the role of excipients on the stability of the product. Prepared tablets were subjected to various quality control tests. Lactose had lower moisture content than MCC. But MCC has moisture scavenger characteristic. Direct-compression CDs with MCC shows less degradation than other tablet formulations. Addition of stearic acid as a substitute for magnesium stearate (a lubricant) changes the overall pH to more acidic which reduces hydrolysis.

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Antonicelli, Mattia, Umberto Liuzzo y Gianfranco Palumbo. "Evaluation of the Effect of a Natural-Based Emulsion on the Cold Rolling Process". Journal of Manufacturing and Materials Processing 7, n.º 4 (23 de junio de 2023): 121. http://dx.doi.org/10.3390/jmmp7040121.

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Lubrication in the cold rolling process plays a key role in withstanding the loads between the strip and the work rolls, as well as in ensuring high surface quality, tight geometric tolerances, and large thickness reductions. Most of the currently used lubricants have synthetic or semi-synthetic formulations, but the research for greener alternatives, able to guarantee very low environmental impact during both the preparation (use of natural raw components) and the disposal, is increasingly playing a key role. In the present work, the lubricating performance of a natural-based emulsion and a mineral-based one has been assessed in terms of rolling forces, Coefficient of Friction (CoF) at the roll/strip interface, and work rolls’ wear. Data from the two-stands reversing cold mill (RCM) at the Marcegaglia plant (Ravenna, Italy) were used for comparing the investigated lubricants. In particular, data about the forces and the wear evolution during the rolling process were acquired over quite a long period (11 months), thus being related to a large type of steel. In addition, the CoF was evaluated using the CSM High-Temperature pin-on-disk Tribometer (THT) and replicating the operating conditions in which the two lubricants are currently used. Laboratory tests revealed that the green lubricant is characterized by a better lubricating performance (the CoF value of the green lubricant is about 10% lower than the one of the semi-synthetic formulation). Such a result was confirmed by both the rolling forces (an average reduction equal to 5.6% was obtained by using the green lubricant) and by the work rolls’ wear (less frequent maintenance of the rolls), thus determining a large and valuable reduction of the process-related costs.

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Timm, Dagmar, Christel Kurowski, Uwe Grummisch, Ulrich Meyhack y Horst Grunewald. "Applications of near Infrared Spectroscopy for Qualification of Lubricants and other Mineral Oil Products". Journal of Near Infrared Spectroscopy 6, A (enero de 1998): A243—A246. http://dx.doi.org/10.1255/jnirs.202.

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This is a poster presentation. Near infrared (NIR) spectroscopy is now recognised worldwide as technology appropriate for industrial quality and process control. NIR is used not only for quantitative analysis but also for identification of materials anywhere in the formulation process: raw materials, intermediates, and finished products. Additives for lubricants like oxidation inhibitors, corrosion inhibitors, and metal deactivators are highly specialised chemicals. Their function is an important part of the lubricant behavior. Some are readily distinguished because their NIR spectra are different. Similar compounds with nearly identical NIR spectra require special chemometric treatment in order to identify them as a proper substance. These same chemometric methods can be used to qualify the material as the specified grade and quality. Water soluble cooling lubricants are used in the metal working industry. The durability of the lubricant in process depends on the amount of impurities by reaction products and hydraulic or other process oils. NIR spectroscopy can be used as quick and effective method to determine the whole oil content and oil impurities continuously (at line) within seconds. The inaccurate and time consuming reference method with the oil tester can be replaced. Along with all the usual benefits of NIR analysis, this identification and qualification method provides a more complete quality assurance program for lubricant production.

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Müller, Camila, Franco Leonardo Redondo, Mariana Dennehy, Andrés Eduardo Ciolino y Walter Roberto Tuckart. "Bismuth (III) sulfide as additive: towards better lubricity without toxicity". Industrial Lubrication and Tribology 70, n.º 2 (12 de marzo de 2018): 347–52. http://dx.doi.org/10.1108/ilt-03-2017-0051.

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Purpose The purpose of this study is to design a fluid formulation with good lubricant properties by using an environmentally friendly additive for: high and low contact pressure conditions and steel/steel and polymer/steel systems. Design/methodology/approach Bismuth (III) sulfide (Bi2S3, “green chemistry” synthesis) is added to a commercial vinyl-terminated silicone fluid (PDMS-Vi) to obtain different weight-per cent mixtures. Tribological performance of formulations is studied from Reichert’s tests (steel/steel system) and block on ring tests (polymer/steel). The results are compared with formulations prepared with commercial bismuth (III) sulfide (Bi2S3), molybdenum (IV) sulfide (MoS2) and graphite. Findings An orthorhombic crystal lattice (XRD ) and a high-purity product (XRF) are evidenced for synthesized Bi2S3. Lubricant properties increase when the weight-per cent of the synthesized Bi2S3 increases in formulations. The wear area decreases up to 90 per cent according to Reichert’s tests. The synthesized Bi2S3 shows a better tribological behavior when compared to commercial Bi2S3, MoS2 and graphite. Originality/value Replacement of lead derivatives by an environmentally friendly lubricant in extreme pressure (EP) formulations and excellent performance compared to commercially used additives are achieved.

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17

Kumar, Vivek y Satish C. Sharma. "Finite element method analysis of hydrostatic thrust pad bearings operating with electrically conducting lubricant". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, n.º 10 (22 de marzo de 2018): 1318–31. http://dx.doi.org/10.1177/1350650117753530.

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A theoretical investigation has been carried out to explore the use of electrically conducting fluids as lubricants in circular and elliptical hydrostatic thrust pad bearings subjected to transverse magnetic field. Flow of electrically conducting fluid in the presence of external transverse magnetic field is represented by the addition of Lorentz force in Navier–Stokes equation. A MATLAB source code based on finite element formulation of the modified Reynolds equation is developed for obtaining static and dynamic characteristics parameters of the bearing. Influence of aspect ratio (major/minor-axis) and magnetic field (Hartmann number) are analyzed on the performance of elliptical pad bearing. Application of electrically conducting lubricant in the elliptical pad is observed to provide higher values of fluid film stiffness (44.93%) and damping (139.37%) coefficients as compared to the circular pad operating with Newtonian lubricant.

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Mohan, C. B., K. Venkatesh, C. Divakar, K. Gopalakrishna, L. Murali y K. G. Lakshminarayana Bhatta. "Development of novel additives for slide way lubricants". Industrial Lubrication and Tribology 67, n.º 2 (9 de marzo de 2015): 110–18. http://dx.doi.org/10.1108/ilt-06-2012-0059.

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Purpose – The paper aims to address the formulation of zirconium and oxalicum additive-based lubricants for use in slide ways to meet the demands of high positioning exactness based on reduction in stick–slip and coefficient of friction over a wide speed range and compares the same with commercially available lubricant. Design/methodology/approach – An investigation into the frictional properties and stick-slip behavior of lubricating oil is carried out using linear reciprocating tribometer and correlated with ultraviolet spectroscopic analysis. Findings – It is observed that these transition metal additive compounds support in increasing the flexibility of the molecular chains leading to improved lubricity. Originality/value – The lubricant additives considered for the current study are based on transition metals zirconium and oxalicum. It is observed that these additive compounds support in increasing the flexibility of the molecular chains, leading to improved lubricity.

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Sultana, S., MZ Haque y HP Nur. "Preparation and application of different size materials on the cotton yarn and investigating the effect of sizing on the tensile properties of cotton yarn". Bangladesh Journal of Scientific and Industrial Research 49, n.º 1 (8 de mayo de 2014): 25–30. http://dx.doi.org/10.3329/bjsir.v49i1.18850.

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Sizing of the cotton yarn is essential to reduce breakage of the yarn due to abrasion during weaving process. The sizing agent on the woven fabric after weaving needs to remove completely before the next textile production process of dyeing and finishing. So, water soluble sizing agent is easy to handle and easy to desizing for pre-treatment of woven fabric. In this work, different types of water soluble tamarind seed kernel based sizing formulations (assigned by A, B and C) were made and applied on cotton yarn to investigate the effect on the tensile properties of sized and unsized cotton yarns. Cotton yarn treated with size B formulation shows the better tensile properties than the application of size A and size C formulation. The effect of lubricant has also been investigated and shows that the addition of lubricant decreases the tensile properties of the cotton yarn. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18850 Bangladesh J. Sci. Ind. Res. 49(1), 25-30, 2014

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Ngaile, G., J. Cochran y D. Stark. "Formulation of polymer-based lubricant for metal forming". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 221, n.º 4 (abril de 2007): 559–68. http://dx.doi.org/10.1243/09544054jem659.

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Kalinin, A. A. y V. G. Mel'nikov. "Optimization of composition of water-base lubricant formulation". Chemistry and Technology of Fuels and Oils 21, n.º 9 (septiembre de 1985): 481–83. http://dx.doi.org/10.1007/bf00735127.

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Simran, Tanwar, Tikariya Komal y Sharma Vimukta. "Formulation and Evaluation of Sustained Release Matrix Tablet of Nimesulide Using Pomegranate Peel and Acacia". International Journal of Pharmaceutical Sciences and Medicine 7, n.º 7 (30 de julio de 2022): 11–24. http://dx.doi.org/10.47760/ijpsm.2022.v07i07.002.

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The main objective of the study is the formulation and evaluation of sustained release matrix tablet of Nimesulide using pomegranate peel and acacia as natural polymer. The preformulation study of Nimesulide was conducted and λmax was found at 300 nm. The sustained release matrix tablet was prepared using Pomegranate peel as Release rate retardant, Acacia as polymer, Polyvinylpyrrolidone K30 as Binder, Isopropyl alcohol as Granulation solution, Micro Crystalline Cellulose as Diluent, Magnesium stearate as Lubricant and Talc as Glidant. Several formulations were prepared by taking different drug concentration in Pomegranate peel (Release rate retardant) with varying ratio of binder to lubricants. Various formulations of sustained release matrix tablet of Nimesulide F1, F2, F3, F4, F5, F6 was prepared. The prepared granules were evaluated for different parameters like Bulk density, Tapped density, Angle of repose, Carr’s index, Hausner’s ratio which shows the excellent flow properties of formulation. The physical characteristic of Nimesulide sustained release matrix tablets (F1 to F6) such as thickness, diameter, hardness, friability, weight variation and drug content were determined and results of the formulations (F1 to F6) found to be within the limits specified in official books. The drug content of all the formulation were found to be in the range of 99.59 to 99.83 % w/w, which is within the specified limit as per Indian Pharmacopoeia 1996 (i.e. 90-110% w/w). The drug released from formulation F1 to F3 was found to be 93.7, 92.9 and 92.2 % for Nimesulide respectively. The drug released from formulation F4 to F6 was found to be 94.1, 93.9 and 92.8% for Nimesulide respectively. The release rate of F1 and F4 was found to be higher when compared to other formulations this is due to increase in the concentration of polymer. These results are indicating that has higher drug retarding ability for long duration. All the formulations were analyzed for stability testing. All the formulations from F1 to F6 were found to be stable.

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Ng, Dalia, Juan Carlos Altamirano-Vallejo, Alejandro Gonzalez-De la Rosa, Jose Navarro-Partida, Jorge Eugenio Valdez-Garcia, Ricardo Acosta-Gonzalez, Juan Carlos Martinez Camarillo, Andres Bustamante-Arias, Juan Armendariz-Borunda y Arturo Santos. "An Oral Polyphenol Formulation to Modulate the Ocular Surface Inflammatory Process and to Improve the Symptomatology Associated with Dry Eye Disease". Nutrients 14, n.º 15 (7 de agosto de 2022): 3236. http://dx.doi.org/10.3390/nu14153236.

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Due to their antioxidant, anti-inflammatory, neuroprotective, and anti-angiogenic effects, polyphenols are first-rate candidates to prevent or treat chronic diseases in which oxidative stress-induced inflammation plays a role in disease pathogenesis. Dry eye disease (DED) is a common pathology, on which novel phenolic compound formulations have been tested as an adjuvant therapeutic approach. However, polyphenols are characterized by limited stability and solubility, insolubility in water, very rapid metabolism, and a very short half-life. Thus, they show poor bioavailability. To overcome these limitations and improve their stability and bioavailability, we evaluated the safety and efficacy of an oral formulation containing among other compounds, polyphenols and omega-3 fatty acids, with the addition of a surfactant in patients with DED. Subjects were randomly assigned to one of four study groups including the study formulation (A), placebo (P), the study formulation + eye lubricant (A + L), and placebo + eye lubricant (P + L). Patients from the A and P groups were instructed to take two capsules every 24 h, while patients in the L groups also added one drop of lubricant twice a day for 12 weeks as well. Regarding safety, non-ocular abnormalities were observed during study formulation therapy. Liver function tests did not show any statistically significant difference (baseline vs. week 4). Concerning efficacy, there was a statistically significant difference between baseline, month 1, and month 3 in the OSDI (Ocular Surface Disease Index) test results in both treatment groups (group A and group A + L). Furthermore, both groups showed statistically significant differences between baseline and month 3 regarding the non-invasive film tear breakup time (NIF-BUT) score and a positive trend related to Shirmer’s test at month 3. The non-invasive average breakup time (NIAvg-BUT) score showed a statistically significant difference at month 3 when compared with baseline in the A + L group. The P + L group showed a statistically significant difference in terms of the OSDI questionary between baseline and month 3. Regarding the lissamine green staining, the A + L group showed a statistical difference between baseline and month 3 (p = 0.0367). The placebo + lubricant group did not show statistically significant differences. Finally, the placebo group did not show any data with statistically significant differences. Consequently, this polyphenol formulation as a primary treatment outperformed the placebo alone, and the polyphenol oral formulation used as an adjuvant to artificial tears was superior to the combination of the placebo and the artificial tears. Thus, our data strongly suggest that this polyphenol oral formulation improves visual strain symptoms and tear film status in patients with mild to moderate DED.

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Kuti, Rajmund, Ádám István Szabó y Álmos Dávid Tóth. "Experimental Investigation of Tribological Properties of Two Fully Formulated Engine Oils with Additional Nanoscale Spherical Zirconia Particles". Lubricants 10, n.º 10 (30 de septiembre de 2022): 246. http://dx.doi.org/10.3390/lubricants10100246.

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Decreasing harmful emissions of vehicle engines is becoming more and more challenging due to stricter standards. A possible solution is to improve the tribological attributes of lubricants, which can be achieved through the application of appropriate additives. According to preliminary studies conducted by the authors, ZrO2 (zirconium-dioxide) nano-sized ceramic particles as lubricant additives have overwhelmingly positive tribological attributes in the presence of non-metallic superficial materials. Additive concentration, as well as cross-effects with other additives were investigated in order to determine a formulation resulting in optimal tribological attributes. In this paper, the experimental investigation of ZrO2 nano-ceramic powder as a lubricant additive is presented. The tribological performance of individually samples were experimentally investigated on a ball-on-disc translational tribometer. The experiments revealed an optimal additive content of 0.3 wt%. Increasing the quantity of additives further ruined friction and wear properties of the examined tribological system.

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25

Uzunović, Alija y Edina Vranić. "Effect of Magnesium Stearate Concentration on Dissolution Properties of Ranitidine Hydrochloride Coated Tablets". Bosnian Journal of Basic Medical Sciences 7, n.º 3 (20 de agosto de 2007): 279–83. http://dx.doi.org/10.17305/bjbms.2007.3060.

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Most pharmaceutical formulations also include a certain amount of lubricant to improve their flowability and prevent their adhesion to the surfaces of processing equipment. Magnesium stearate is an additive that is most frequently used as a lubricant. Magnesium stearate is capable of forming films on other tablet excipients during prolonged mixing, leading to a prolonged drug liberation time, a decrease in hardness, and an increase in disintegration time. It is hydrophobic, and there are many reports in the literature concerning its adverse effect on dissolution rates.The objective of this study was to evaluate the effects of two different concentrations of magnesium stearate on dissolution properties of ranitidine hydrochloride coated tablet formulations labeled to contain 150 mg. The uniformity content was also checked.During the drug formulation development, several samples were designed for choice of the formulation. For this study, two formulations containing 0,77 and 1,1% of magnesium stearate added in the manufacture of cores were chosen. Fraction of ranitidine hydrochloride released in dissolution medium was calculated from calibration curves. The data were analyzed using pharmaco-peial test for similarity of dissolution profiles (f2 equation), previously proposed by Moore and Flanner.Application of f2 equation showed differences in time-course of ranitidine hydrochloride dissolution properties. The obtained values indicate differences in drug release from analyzed ranitidine hydrochloride formulations and could cause differences in therapeutic response.

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26

Magalhães, Luís, Ramiro Martins, Ivo Oliveira y Jorge Seabra. "Comparison of tooth profiles and oil formulation focusing lower power losses". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 226, n.º 6 (7 de marzo de 2012): 529–40. http://dx.doi.org/10.1177/1350650112439260.

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Environmental awareness, lower consumption of raw materials and longer life of equipment are main concerns nowadays and are leading to the research and development of lubricants and equipment to access those requirements. In this study, the power loss performance of three different tooth profile geometries, developed with the purpose of decreasing power losses while keeping the predicted life, were tested and evaluated in a FZG test rig. The path to reduce power losses was based on the decrease of the module, the increase of the helix angle and increase of the addendum modification coefficients in order to reduce the path of contact, i.e. the sliding velocity. The power loss behaviour of two different lubricants was also evaluated for each tooth profile geometry considered. The influence of the oil level in the gearbox was also evaluated. One of the lubricants has an ester base while the other has a polyalphaolefin base and both are fully formulated. An energetic model was developed for the FZG test gearbox and applied to these tests to improve the knowledge about the influence of tooth geometries as well as lubricant formulation in the power losses and coefficient of friction between gear teeth. The developed geometries showed that the path followed for the reduction of power losses produced the expected results and can be implemented with success on gear design.

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27

Leighton, M., T. Nicholls, M. De la Cruz, R. Rahmani y H. Rahnejat. "Combined lubricant–surface system perspective: Multi-scale numerical–experimental investigation". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, n.º 7 (12 de diciembre de 2016): 910–24. http://dx.doi.org/10.1177/1350650116683784.

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Frictional losses are one of the main causes of reduced energy efficiency in all machines and mechanisms. In particular, there is mounting pressure upon manufacturers of all forms of vehicle to comply with increasingly stringent legislation and directives with regard to harmful emissions. Therefore, reduction of friction has become an imperative issue. The traditional approach of dealing with surface material and lubricant formulation in isolation has been replaced by a lubricant–surface system approach. This paper presents multi-scale experimentation from nano/meso-scale lateral force microscopy of ultra-thin surface adsorbed films through to micro-scale precision sliding tribometry to investigate lubricant–surface friction optimisation within the mixed regime of lubrication, using lubricants with different organic and inorganic friction modifying species. These affect the parameters of the system, commonly used as input to models for mixed and boundary regimes of lubrication. Therefore, the precise measurement of these parameters at different physical scales is important. The study also makes use of detailed numerical predictions at micro-scale through combined solution of the average Reynolds equation as well as interaction of wetted asperities in mixed and boundary regimes of lubrication. Good agreement is found between the predictions and measurements at micro-scale tribometric interactions. Furthermore, the same trends are observed in testing across the physical scales.

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28

Brahmaiah, B., K. Sasikanth, Sreekanth Nama, P. Suresh y Patan Adam Khan. "Formulation and Dissolution Study of Valsartan Immediate Release Tablets". Indian Journal of Pharmaceutical and Biological Research 1, n.º 02 (30 de junio de 2013): 01–08. http://dx.doi.org/10.30750/ijpbr.1.2.1.

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In the present study, design of oral immediate release tablets of Valsartan by direct compression technique was carried out. The main aim and objective of the work is to formulate immediate release tablets using different direct compression vehicles (DCV’S) in different ratios. The main motive is to compare the dissolution profile of these formulations and conclude the best formulation which release drug at a faster rate. To determine the best fit dissolution profile for the dosage forms. Valsartan tablets were formulated by using microcrystalline cellulose (diluents), potato starch, acacia (binder) and magnesium stearate (lubricant). The granules were compressed into tablets and were subjected to dissolution studies. The dissolution profile of the formulation F2 was found to have better dissolution rate compared to others. The In-vitro dissolution studies of all the formulations were conducted and the results were obtained, it was concluded that formulation F2 was the best with fast release of drug compared to others.

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29

Badawi, Aliaa A., Mahmoud M. Hegazy, Dina Louis y Mohammed A. Eldegwy. "Solving manufacturing problems for L-carnitine-L-tartrate to improve the likelihood of successful product scale-up". Acta Pharmaceutica 67, n.º 4 (20 de diciembre de 2017): 511–25. http://dx.doi.org/10.1515/acph-2017-0033.

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AbstractL-carnitine-L-tartrate, a non-essential amino acid, is hygroscopic. This causes a problem in tablet production due to pronounced adhesion of tablets to punches. A 33 full factorial design was adopted to suggest a tablet formulation. Three adsorbents were suggested (Aerosil 200, Aerosil R972, talc) to reduce stickiness at three concentrations (1, 3 and 5 %), and three fillers (mannitol, Avicel PH 101, Dibasic calcium phosphate) were chosen to prepare 27 formulations. Micromeritic properties of formulations were studied, and tablets were prepared by wet granulation. Absence of picking, sticking or capping, recording of sufficient hardness, acceptable friability and tablet ejection force indicated formulation success. The resulting formulation prepared using Avicel PH 101 and 1 % Aerosil 200 was submitted to further investigation in order to choose the most suitable compression conditions using a 33full factorial design. Variables included compression force, tableting rate and magnesium stearate (lubricant) concentration. The formulation prepared at compression force of 25 kN, using 2 % magnesium stearate, at a production rate of 30 tablets/ minute, was found to be the most appropriate scale up candidate.

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Abd Elbary, Ahmed, Howida K. Ibrahim y Balquees S. Hazaa. "Understanding the formulation variables of orodispersible tablets containing simvastatin solid dispersion using Box-Behnken design". Drugs and Therapy Studies 2, n.º 1 (12 de marzo de 2012): 7. http://dx.doi.org/10.4081/dts.2012.e7.

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Simvastatin is a well established oral antihypercholesterolemic agent. This study aimed to formulate simvastatin as orodispersible tablets. The drug was incorporated as a solid dispersion using Pluronic® F68 as carrier. Croscarmellose Na was used as superdisintegrant, microcrystalline cellulose as filler, PVP K-30 as binder and 1:1 magnesium stearate/talc mixture as lubricant. Box- Behnken design was adapted to explore the main and interaction effects of three independent formulation variables on the prepared tablets, namely superdisintegrant concentration (X1), lubricant mixture concentration (X2), and binder concentration (X3). A total of 13 tablet formulations were fabricated in addition, to two replicates of the center point to assess variability and experimental error. The selected dependant variables were the<em> in vitro</em> and <em>in vivo</em> disintegration times, dissolution rate at 4 min, and dissolution efficiency after 30 min. Wetting time, drug content, hardness and friability were also evaluated. Tablet formula, composing of 12% superdisintegrant, 2% lubricant mixture and 3% binder, showed the highest dissolution rate with an acceptable disintegration time (43 sec), hardness, and friability and was chosen as the best formula. An accelerated stability study was conducted for 6 months at 40°C/75% RH. Results showed no significant changes in any of the tested parameters.

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31

Jang, J. Y. y M. M. Khonsari. "On the Role of Enduring Contact in Powder Lubrication". Journal of Tribology 128, n.º 1 (7 de julio de 2005): 168–75. http://dx.doi.org/10.1115/1.2114933.

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This paper is devoted to a study of the enduring contact between granules of powder lubricants in an effort to better understand the flow characteristics of powder lubricants. Appropriate formulation of the governing equations is reported that can be used for prediction of the flow velocity, pseudo temperature, and volume fraction distribution of powders for a wide range of operating speeds. A set of parametric simulations and a limiting analytical solution is presented for predicting the behavior of a powder lubricant under low operating speeds when the enduring contact tends to dominate the kinetic regime. The limiting solution shows that below a certain sliding speed the volume fraction remains unchanged due to the effect of the enduring contact. It is also shown that below this limiting speed the enduring contact plays a major role and should not be neglected.

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32

Goodwin, Sophie R., Amy Stimpson, Richard Moon, Lauren Cowie, Najib Aragrag, Sorin V. Filip, Andrew G. Smith y Derek J. Irvine. "Facile Synthesis of Functionalised Hyperbranched Polymers for Application as Novel, Low Viscosity Lubricant Formulation Components". Polymers 14, n.º 18 (14 de septiembre de 2022): 3841. http://dx.doi.org/10.3390/polym14183841.

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A novel, previously unreported, method for synthesising hyperbranched (HB) materials is detailed. Their use as additives to produce lubricant formulations that exhibit enhanced levels of wear protection and improved low-temperature oil viscosity and flow is also reported. The lubricant formulations containing HB additives were found to exhibit both significantly lower viscosities and improved in-use film-forming properties than the current industry standard formulations. To achieve this, alkyl methacrylate oligomers (predominantly dimers and trimers) were synthesised using catalytic chain transfer polymerisation. These were then used as functional chain transfer agents (CTA) to control the polymerisation of divinyl benzene (DVB) monomers to generate highly soluble, high polydispersity HB polymers. The level of dimer/trimer purification applied was varied to define its influence on both these HB resultant structures and the resultant HB additives’ performance as a lubricant additive. It was shown that, while the DVB acted as the backbone of the HB, the base oil solubility of the additive was imparted by the presence of the alkyl chains included in the structure via the use of the oligomeric CTAs.

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33

Rahim, Haroon, Mir Azam Khan, Amin Badshah, Kamran Ahmad Chishti, Salimullah Khan y Muhammad Junaid. "Evaluation of Prunus domestica gum as a novel tablet binder". Brazilian Journal of Pharmaceutical Sciences 50, n.º 1 (marzo de 2014): 195–202. http://dx.doi.org/10.1590/s1984-82502011000100020.

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To evaluate binding potential of Prunus domestica gum in tablets formulations. Six tablet batches (F-1B to F-6B) were prepared by wet granulation method, containing Avicel pH 101 as diluent, sodium diclofenac as model drug using 10, 15 and 20 mg of Prunus domestica gum as binder and PVP K30 was used as standard binder. Magnesium stearate was used as lubricant. Flow properties of granules like bulk density, tapped density, Carr index, Hausner’s ratio, angle of repose as well as physical parameters of the compressed tablets including hardness, friability, thickness and disintegration time were determined and found to be satisfactory. The FTIR spectroscopic analysis showed that the formulation containing plant gum is compatible with the drug and other excipients used in tablets formulation. Hence the plant gum has role as a potential binder in tablets formulations. The dissolution profile showed that tablets formulations containing Prunus domestica gum 15 mg/200 mg of total weight of tablet as binder showed better results as compared to PVP K30.

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34

Xu, H. y A. Kahraman. "Prediction of friction-related power losses of hypoid gear pairs". Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 221, n.º 3 (1 de septiembre de 2007): 387–400. http://dx.doi.org/10.1243/14644193jmbd48.

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A model to predict friction-related mechanical efficiency losses of hypoid gear pairs is proposed in this study. The model includes a gear contact model, a friction prediction model, and a mechanical efficiency formulation. The friction model uses a friction coefficient formula obtained by applying multiple linear regression analysis to a large number of elastohydrodynamic lubrication analyses covering typical ranges of key parameters associated with surface roughness, geometry, load, kinematics, and the lubricant. Formulations regarding the kinematic and geometric properties of the hypoid gear contact are presented. The load and friction coefficient distribution predictions are used to compute instantaneous torque/power losses and the mechanical efficiency of a hypoid gear pair at any given position. Results of a parametric study are presented at the end to highlight the influence of key operating conditions, surface finish, and lubricant properties on mechanical efficiency losses of hypoid gears.

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35

Sander, John, Terry Smith, Patrick Bilberry, In-Sik Rhee y S. W. Dean. "Luminescent Bacteria as an Indicator Species for Lubricant Formulation Ecotoxicity". Journal of ASTM International 9, n.º 1 (2012): 103673. http://dx.doi.org/10.1520/jai103673.

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36

Fernandez-del-Rincon, A., A. Diez-Ibarbia, M. Iglesias y F. Viadero. "Gear rattle dynamics: Lubricant force formulation analysis on stationary conditions". Mechanism and Machine Theory 142 (diciembre de 2019): 103581. http://dx.doi.org/10.1016/j.mechmachtheory.2019.103581.

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37

Kim, Nam Chul y Sung Ho Song. "Effects of Zinc-Free Processing Aids on Silica-Reinforced Tread Compounds for Green Tires". International Journal of Polymer Science 2019 (25 de junio de 2019): 1–9. http://dx.doi.org/10.1155/2019/9123635.

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With the development of “green tires” in the tire industry, the conventional carbon black filler that is used in tread formulations is being replaced with silica. Generally, this requires the addition of a processing aid, containing zinc ion, which acts as a lubricant and dispersing agent. However, because zinc is a heavy metal, zinc-free processing aids (ZFAs) are required to satisfy worldwide environmental concerns. We present herein a series of catalytically synthesized ZFAs and evaluate the effects of replacing zinc ion-containing processing aids (ZCAs) on a silica tread formulation. Interestingly, replacing ZCA with ZFA in a two parts per hundred rubber (phr) by weight formulation improved both its tensile strength and elongation by as much as 31% and 20%, respectively. ZFA-rubber formulations also exhibited a twofold enhancement in fatigue properties over those of ZCA-rubber formulations. Furthermore, pneumatic tires were fabricated from our ZFA-rubber formulation and compared against tires containing ZCAs. The ZFA-rubber composite exhibited improved dry and wet braking and rolling resistance due to enhanced dispersion of silica in the rubber matrix. These results show that rubber composites prepared with ZFAs may be promising in tire engineering applications.

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38

L’Hostis, Benoit, Clotilde Minfray, Marion Frégonèse, Catherine Verdu, Benoit Ter-Ovanessian, Béatrice Vacher, Thierry Le Mogne, Frédéric Jarnias y Alder Da-Costa D’Ambros. "Influence of lubricant formulation on rolling contact fatigue of gears – interaction of lubricant additives with fatigue cracks". Wear 382-383 (julio de 2017): 113–22. http://dx.doi.org/10.1016/j.wear.2017.04.025.

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39

Dai, Yao, Fuwei Lu, Yuhua Tang, Yuanyuan Wang, Xinyi He, Tengfei Wang y Juan Wu. "The Simulation of Ester Lubricants and Their Application in Weak Gel Drilling Fluids". Gels 10, n.º 3 (3 de marzo de 2024): 178. http://dx.doi.org/10.3390/gels10030178.

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To enhance the performance and reduce the amount of ester-based lubricants used in weak gel drilling fluids, a shear dynamics simulation under extreme pressure conditions was employed to refine the formulation of the base oil and pressure additives. The simulation results were validated using fatty acid methyl, ethyl, and butyl esters. Fatty acid methyl ester demonstrated the lowest temperature increase and the highest load-bearing capacity post-shear. The four-ball friction test revealed that methyl oleate had a coefficient of friction of 0.0018, approximately a third of that for butyl oleate, confirming the simulation’s accuracy. By using methyl oleate as the base oil and oleamide as the pressure-resistant component, the optimal shear stress was achieved with a 10% addition of oleamide. A lubricant composed of 90% methyl oleate and 10% oleamide was tested and showed a coefficient of friction of 0.03 when 0.5% was added to bentonite slurry, indicating a strong lubricating film. Adding 1% of this lubricant to a low gel drilling fluid system did not affect its rheological properties, and the gel structure remained stable after seven days of aging. Field tests at the Fu86-3 well in the Jiangsu Oilfield of Sinopec confirmed that adding 1% of the ester-based lubricant to the drilling fluid significantly improved drilling efficiency, reduced drag by an average of 33%, and increased the drilling rate to 22.12 m/h. This innovation effectively prevents drilling complications and successfully achieves the objectives of enhancing efficiency.

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40

Kim, Kyung-Hoon y Farshid Sadeghi. "Three-Dimensional Temperature Distribution in EHD Lubrication: Part II—Point Contact and Numerical Formulation". Journal of Tribology 115, n.º 1 (1 de enero de 1993): 36–45. http://dx.doi.org/10.1115/1.2920984.

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A numerical study of Newtonian thermal elastohydrodynamic lubrication (EHD) of rolling/sliding point contacts has been conducted. The two-dimensional Reynolds, elasticity and the three-dimensional energy equations were solved simultaneously to obtain the pressure, film thickness and temperature distribution within the lubricant film. The control volume approach was employed to discretize the differential equations and the multi-level multi-grid technique was used to simultaneously solve them. The discretized equations, as well as the nonorthogonal coordinate transformation used for the solution of the energy equation, are described. The pressure, film thickness and the temperature distributions, within the lubricant film at different loads, slip conditions and ellipticity parameters are presented.

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41

Chen, Zhuo Jun y Long Long Feng. "Based on the PB Neural Network of Optimization Design in Lubricant Additives". Advanced Materials Research 311-313 (agosto de 2011): 218–22. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.218.

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This article use the Sulphide Isobutene, Five Sulfides Dialkyl, and Star of Phosphorus as the additives, Neopentyl Polyol Ester (NPE) as base oil for screening lubricant formulation. The purpose of this article is screening the lubricant additives formula. Apply the BP neural network method in optimization design. Through the optimization of lubricant additive formula select the best formula for experiment. The selected best formula is Sulphide Isobutene 0.8%(mass percent), Five Sulfides Dialkyl 1.2%(mass percent) , Star of Phosphorus 1.6%(mass percent), relative error is 0.089.After validation experiment，it is conclusion that S-type blends with P-type additive use will acquire good result, and the method of optimal convergence faster, the forecast precision test is satisfied.

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42

Skerlos, Steven J., N. Rajagopalan, Richard E. DeVor, Shiv G. Kapoor y V. Don Angspatt. "Ingredient-Wise Study of Flux Characteristics in the Ceramic Membrane Filtration of Uncontaminated Synthetic Metalworking Fluids, Part 2: Analysis of Underlying Mechanisms". Journal of Manufacturing Science and Engineering 122, n.º 4 (1 de noviembre de 1999): 746–52. http://dx.doi.org/10.1115/1.1286131.

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Part 2 of this paper reveals the predominant mechanism of flux decline during microfiltration of the synthetic MWF described in Part 1 of this paper. An analysis of flux data obtained during the experimental investigation suggests that adsorptive interactions occur at the membrane surface. Field Emission Environmental Scanning Electron Microscopy (FE-ESEM) images of aluminum oxide membranes after MWF microfiltration illustrate that adsorption leads to a reduction in pore diameter that serves to reduce flux. The majority of the adsorption is accounted for by a single lubricant additive in the MWF formulation. FE-ESEM images also reveal that the mechanism of flux decline for the defoamer varies depending on the presence of lubricant additive in solution. In the absence of lubricant additive, the defoamer forms a cake layer at the membrane surface. In the presence of the lubricant additive, the defoamer adsorbs to the surface of the membrane with the lubricant additive to constrict pores. In contrast to the lubricant additive and defoamer, base fluid flux decline observed after specialty additive exposure cannot be accounted for by adsorption leading to pore constriction. [S1087-1357(00)01203-X]

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43

Lanigan, J. L. y R. Lewis. "Understanding friction mechanisms of Si-DLC/steel interfaces under aqueous lubrication". RSC Advances 13, n.º 15 (2023): 10322–37. http://dx.doi.org/10.1039/d2ra07578d.

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A key driver in current research on lubricant formulation is the need to move away from older technology that is highly reliant on resources derived from industries associated with high carbon dioxide emissions.

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44

Szabó, Zoltán-István, Blanka Székely-Szentmiklósi, Boglárka Deák, István Székely-Szentmiklósi, Béla Kovács, Katalin Zöldi y Emese Sipos. "Study of the effect of formulation variables on the characteristics of combination tablets containing enalapril maleate and indapamide as active substances using experimental design". Acta Pharmaceutica 66, n.º 2 (1 de junio de 2016): 191–206. http://dx.doi.org/10.1515/acph-2016-0019.

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Abstract To evaluate the influence of different variables on tablet formulations containing enalapril maleate and indapamide as active substances, two separate experimental designs were employed: one for evaluating powder properties and the other for tablet characteristics. Because of the low active pharmaceutical ingredient content, it was hypothesized that both powder and tablet properties could be determined only by the characteristics of excipients. In order to test this assumption, both experimental designs were done with placebo mixtures. The optimized formulation was then evaluated both with and without APIs. Results indicated that filler and lubricant percentage, along with compression force, were the most important variables during the formulation study. The optimized formulation showed similar characteristics in both cases for all responses, except for angle of repose and friability where only minor differences were observed. The combination of the applied approaches (using placebo composition and fractional experimental design) proved to be efficient, cost effective and time saving.

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45

Yadav, Saurabh Kumar, Arvind Kumar Rajput, Nathi Ram y Satish Chandra Sharma. "A novel technique to compute static and dynamic performance characteristics of aerostatic thrust bearing". Industrial Lubrication and Tribology 70, n.º 1 (8 de enero de 2018): 84–96. http://dx.doi.org/10.1108/ilt-04-2017-0090.

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Purpose This study aims to analyze the dynamic performance of aerostatic thrust bearing for different geometries of recess. Different geometries of recess of equal recess area, i.e. circular, elliptical, rectangular and annular, have been considered in analysis. The work also analyzes the influence of tilt angle on the performance of thrust bearing. To compute the unknown pressure field, the Reynolds equation governing the flow of compressible lubricant (air) has been solved using finite element formulation. Further, separate finite element formulations have been carried out to compute fluid film stiffness and damping coefficients directly. This method provides quick computation of stiffness and damping coefficients of aerostatic thrust bearing than the usual approach. Design/methodology/approach As the Reynolds equation governing the flow of compressible lubricant is nonlinear partial differential equation, the computation of the stiffness and damping coefficient follows an iterative procedure. It requires a lot of computational energy. Therefore, in the present work, a novel technique based on finite element formulation is suggested to compute air film stiffness and damping coefficient in aerostatic thrust bearing. Findings A novel technique based on finite element formulation is illustrated to simulate the performance of tilted pad aerostatic thrust bearing. On the basis of simulated results, following key conclusions may be drawn. The static and dynamic performance of a circular aerostatic tilted thrust pad bearing is significantly affected with a change in the value of tilt parameter and the shape of the recess. Research limitations/implications Implications are as follows: direct computation of air film damping coefficient is performed without perturbation method in finite element method (FEM); influence of tilt on aerostatic thrust bearing is studied; influence of recess shape on aerostatic thrust bearing is observed; and finite element formulation of aerostatic thrust bearing is performed. Originality/value The present work will be quite useful for bearing designer and academicians.

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46

Pandey, Priya, Anthony E. Somers, Samik K. Hait, Maria Forsyth y S. S. V. Ramakumar. "A novel approach to improve the oil miscibility and incorporate multifunctionality in ionic liquids as lubricant additives". Physical Chemistry Chemical Physics 23, n.º 5 (2021): 3429–40. http://dx.doi.org/10.1039/d0cp05295g.

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Recently ionic liquids (ILs) have shown promising tribological properties as additives in base oils; however their lack of miscibility is a problem, with very few ILs being compatible with lubricant oil formulation (non-polar base oils).

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47

Narita, Keiichi. "Tribological Properties of Metal V-Belt Type CVT Lubricant". Advances in Tribology 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/476028.

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The priority for lubricant performance for metal V-belt-type CVT (B-CVTFs) should be the improvement of transmittable torque capacity between the belt and pulley plus excellent antishudder properties for lockup clutch used in B-CVTs. This study intends to investigate the effect of lubricant additives for improving these performances of B-CVTs. In addition, surface analysis techniques were utilized to gain a novel insight into the chemical composites and morphology of the tribofilms. As a result, it is vital for greater torque capacity to give higher boundary friction coefficient between the metal contacting interfaces, and the process of boundary lubricant film formation derived from antiwear additives used in B-CVTFs strongly impacts on the torque capacity. Moreover, it is found that a sort of lubricant formulation gave an excellent antishudder performance for wet clutch with keeping higher friction coefficient between the metals, which would result in improving the performance of B-CVTs.

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Chothani, Hardik y Kalpesh Maniya. "A model formulation for the prediction of churning power loss in worm gear transmission". Tribology and Materials 1, n.º 3 (2022): 87–95. http://dx.doi.org/10.46793/tribomat.2022.012.

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Churning power loss is a complex process that causes significant loss of energy under splash lubrication of gear units. A set of empirical equations are available that allows for precise churning power losses calculation for only the parallel axis gears. The main objective of this study is to formulate a new mathematical model for worm gear based on the experiment result. The mathematical model is formulated using the dimensional analysis method and has been experimentally validated over a wide range of speeds in terms of revolutions, types of lubricants, lubricant temperature, and immersion depths. The simple direct torque measurement method was used to measure the churning loss. The influence of inertia force, viscous force, and gravitational forces were also investigated therefore correlations with Froude and Reynolds numbers are presented. Hardened steel and bronze were used as a material combination of worm and worm gear, respectively. A new formula for worm gear under splash lubrication has been derived and validated by comparison with experimental evidence. A very little discrepancy was found between the experiment result and the mathematical equation.

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Ngo, Dien, Xin He, Huimin Luo, Jun Qu y Seong H. Kim. "Competitive Adsorption of Ionic Liquids Versus Friction Modifier and Anti-Wear Additive at Solid/Lubricant Interface—Speciation with Vibrational Sum Frequency Generation Spectroscopy". Lubricants 8, n.º 11 (12 de noviembre de 2020): 98. http://dx.doi.org/10.3390/lubricants8110098.

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A modern lubricant contains various additives with different functionalities and the interactions or reactions between these additives could induce synergistic or antagonistic effects in tribological performance. In this study, sum frequency generation (SFG) spectroscopy was used to investigate competitive adsorption of lubricant additives at a solid/base oil interface. A silica substrate was used as a model solid surface. The lubricant additives studied here included two oil-soluble ionic liquids (ILs, [N888H][DEHP] and [P8888][DEHP]), an antiwear additive (secondary ZDDP), an organic friction modifier (OFM), and a dispersant (PIBSI). Our results showed that for mixtures of ZDDP and IL in a base oil (PAO4), the silica surface is dominated by the IL molecules. In the cases of base oils containing OFM and IL, the silica/lubricant interface is dominated by OFM over [N888H][DEHP], while it is preferentially occupied by [P8888][DEHP] over OFM. The presence of PIBSI in the mixture of PAO4 and IL leads to the formation of a mixed surface layer at the silica surface with PIBSI as a major component. The SFG results in this investigation provide fundamental insights that are helpful to design the formulation of new lubricant additives of desired properties.

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50

Shi, Fanghui y Qian (Jane) Wang. "A Mixed-TEHD Model for Journal-Bearing Conformal Contacts—Part I: Model Formulation and Approximation of Heat Transfer Considering Asperity Contact". Journal of Tribology 120, n.º 2 (1 de abril de 1998): 198–205. http://dx.doi.org/10.1115/1.2834410.

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A mixed-TEHD (thermal elastohydrodynamic) model was developed for journal bearings working at large eccentricity ratios in order to facilitate a better understanding of mixed-lubrication phenomena for conformal-contact elements. The model consists of a mixed-lubrication process that considers the roughness effect and asperity contact, a thermal process for temperature analyses, and a thermal-elastic process for deformation calculations. In this model, the interactive journal, lubricant, and bearing were treated as an integrated system. Finite-element, finite-difference, and influence-function methods were utilized in the numerical process. The overall solution was achieved by the iteration method. Analyses of a simulated bearing-lubricant-journal system working under mixed-lubrication conditions were conducted, and the influence of the changes of lubricant flows as a result of the asperity contact on the system heat transfer and temperature distributions was numerically investigated.

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