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Ashless Antiwear and Antiscuffing (Extreme Pressure) Additives
Published in Leslie R. Rudnick, Lubricant Additives, 2017
Liehpao Oscar Farng, Tze-Chi Jao
Several novel chemistries are available in the literature for nitrogen-only antiwear additives. Among these, dicyano compounds were tested and exhibited very good four-ball wear activities [82]. Polyimide-amine salts of styrene–maleic anhydride copolymers are also reported as antiwear additives; however, high additive concentrations (5%–10%) are needed [83]. Alkoxylated amines (Structure M) and mixtures of fatty acid, fatty acid amide, imide, or ester derived from substituted succinic acid or anhydride have been identified to be good fuel lubricity additives [84] (Structure M). Alkyl hydrazide additives possessing two adjacent nitrogen atoms have also been claimed to exhibit good antiwear properties [85] (Structure N). Products of nitrogen heterocycles, such as oxadiazole ODZ (Tables 7.2 and 7.3 for performance evaluations), benzotriazole (BZT), tolyltriazole (TTZ), alkyl succinhydrazide (SHDZ), and borated hydroxypyridine (BHPD) (Structures O, P, Q, R, and S, respectively), with pendant alkylates, amines, or carboxylic acids have been found to be effective antiwear additives in both lubricants and fuels [86–92]. Although triazoles are costly chemicals, they have unique geometric structures that contribute high surface film–forming efficiency.
Warm Mix Asphalt (WMA) technologies: Benefits and drawbacks—a literature review
Published in Sandra Erkens, Xueyan Liu, Kumar Anupam, Yiqiu Tan, Functional Pavement Design, 2016
Aboelkasim Diab, Cesare Sangiorgi, Rouzbeh Ghabchi, Musharraf Zaman, Amr M. Wahaballa
Sasobit®, produced by Sasol, is the most commonly used additive in this category. It is commonly used amongst the organic additives and has largely been associated to the discussion. The additive is a fine crystalline long chained aliphatic hydrocarbon, or simply wax (Sasol 2008). Sasobit® has a melting point range of 85–115°C. Therefore, it is completely soluble in asphalt binder at temperatures above 115°C. Sasobit® lowers the viscosity of the binder and also acts as a flow modifier in the mix which facilitates the aggregates free movement and coating by the asphalt binder. Sasobit® can be directly added to the mix during production stage or blended with the asphalt binder and then stored prior to mixing. Then the blend can be used to produce asphalt mixes. Licomont BS 100 is another fatty acid amide which acts as a viscosity enhancer. It is available in both powder and granular forms. The melting point of the Licomont BS 100 is significantly different from the wax additives; because it melts at a temperature range of 140–145°C. Another commercially available organic or wax-based additive is Asphaltan B with the mechanism to facilitate the production of WMA mixtures similar to that of Sasobit®. Based on a study by Rowe et al. (2009), use of Asphaltan B in asphalt binder provided a viscosity reduction similar to that of Sasobit®.
Advances in Osteoarthritis of the Hip
Published in K. Mohan Iyer, Hip Joint in Adults: Advances and Developments, 2018
Pratham Surya, Sriram Srinivasan, Dipen K. Menon
OA is a disease with varied pathophysiology. A workshop on aetiopathogenesis of OA concluded that OA can be idiopathic (aetiology unknown). It was previously believed to be caused by wear and tear of the joint. Currently scientists and researchers believe it to be a disease of the joint. Some factors that have a role in development of hip OA are as follows:Genetic: OA has a significant heritable component. Genes associated with OA tend to be associated with the process of synovial joint development. Mutations in these genes might directly cause OA [9]. Early-age-onset OA is caused by mutations in matrix molecules often associated with chondrodysplasias. Middle-age onset of OA is caused by mutations that predispose the joint to injury or malalignment and late-age-onset OA to mutations that regulate subtle aspects of joint development and structure [9]. Some inherited traits may result in a rare defect where the body does not produce collagen, which is a component protein in cartilage. Recently, researchers found that a gene called FAAH (fatty acid amide hydrolase), which mediates pain, is found to be higher in patients suffering from OA than in a normal person [13]. Other genes that are linked to OA are vitamin D receptor, oestrogen receptor-1 and inflammatory cytokines such as IL-1, IL-4 and matrilin-3.Obesity: A high body mass index (BMI) increases the pressure on lower limb weight-bearing joints such as the hip and knee. It is also proven that an excess of fat tissue induces the production of inflammatory cytokines, which can cause further damage to the joints.Overuse and damage: Occupational hazards such prolonged weight bearing and heavy lifting can lead to damage of the cartilage. Intra-articular fractures lead to OA.Developmental or acquired deformities: Some examples are hip dysplasia, Perthes disease of the hip (Fig. 19.3) and slipped upper femoral epiphysis (SUFE).Joint disorders in athletes: Injuries involving a joint are very common in athletes. Joint injuries occur in professional players, especially soccer players. In every thousand hours on the sports field 10 to 35.5 injuries are reported [13]. Articular cartilage has very poor regenerative properties, leading to OA. A study conducted on soccer players indicates that 32%-49% of the players have OA. In a study it was determined that there is a threefold increased risk of hip OA in elite players than comparatively less elite ones [13].Other or miscellaneous factors: Hormonal disturbances, like an excess of growth hormone, lead to OA. Other joint and metabolic disorders may lead to an increased risk of OA.
Performance of an amide-based inhibitor derived from coffee bagasse oil as corrosion inhibitor for X70 steel in CO2-saturated brine
Published in Green Chemistry Letters and Reviews, 2019
N.B. Gomez-Guzman, D.M. Martinez de la Escalera, J. Porcayo-Calderon, J.G. Gonzalez-Rodriguez, L. Martinez-Gomez
As a corrosion inhibitor, a fatty acid amide synthesized from coffee bagasse oil was used. The synthesis procedure was according to the procedure reported in the literature (5, 8). The details of the synthesis and the characterization of the inhibitor have been reported by the authors in a previous publication (10). According to the studies carried out, the monitoring of the synthesis process (by thin layer chromatography) confirmed the complete conversion of the triglycerides to fatty acid amide. After the purification of the products and their characterization by FTIR spectroscopy, a yield of the synthesis process of 96.9% was obtained. Based on these results, it was established that the molecular structure of the fatty amides synthesized is as shown in Figure 1 in a proportion similar to that of the fatty acid content of the oil used for its synthesis (44.2% linoleic acid, 34.41% palmitic acid, 8.53% oleic acid, 7.56% stearic acid) (10).