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Fulltext Influence of dimple depth on lubricant thickness in elastohydrodynamic lubrication for metallic hip implants using fluid structure interaction (FSI) approach

Mohd Syafiq Mohd Suri, Nor Liyana Safura Hashim, Ardiyansyah Syahrom, Mohd Juzaila Abd. Latif, Muhamad Noor Harun

Malaysian Journal of Medicine and Health Sciences, 2020;16(108):28-34.
MyJurnal

Introduction: The lubricant thickness in clearance between bearing surfaces for metallic hip implants are currently incapable of accommodating the motion experienced (high load and low entraining motion) in hip walking cycle. Thus, micro-dimpled surfaces were introduced onto surfaces of metallic acetabular cups to improve lubricant thick- ness. Micro-dimpled surface is a method of advanced surface improvement to increase the lubricant thickness in various tribological applications, such as hip implants. However, the application of micro-dimpled surfaces in hip implants has not yet been explored adequately. Therefore, this study aims to identify the influence of micro-dimpled depth on lubricant thickness elastohydrodynamically for metallic hip implants using Fluid-Structure Interaction (FSI) approach. Methods: Fluid-Structure Interaction (FSI) approach is an alternative method for analysing characteristics of lubrication in hip implant. Dimples of radius 0.25 mm and various depths of 5μm, 45μm and 100μm were applied on the cup surfaces. The vertical load in z-direction and rotation velocity around y-axes representing the average load and flexion-extension (FE) velocity of hip joint in normal walking were applied on Elastohydrodynamic lubri- cation (EHL) model. Results: The metallic hip implants with micro-dimpled surfaces provided enhanced lubricant thickness, namely by 6%, compared to non-dimpled surfaces. Furthermore, it was suggested that the shallow depth of micro-dimpled surfaces contributed to the enhancement of lubricant thickness. Conclusion: Micro-dimpled sur- faces application was effective to improve tribological performances, especially in increasing lubricant thickness for metallic hip implants.

Matched MeSH terms: Lubrication
Fulltext Effects of lubrication in warm powder compaction process

Rahman, M.M., Nor, S.S.M., Rahman, H.Y.

ASM Science Journal, 2011;5(1):11-18.
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Warm compaction is an advanced manufacturing technique which consists of two consecutive steps, i.e. powder compaction at above ambient temperature and sintering in a controlled environment. Due to the relative movement between the powder mass and die wall as well as sliding among powder particles, frictional force is generated during the compaction stage. Admixed lubricant is used during the compaction step in order to minimize friction and hence improve the uniformity of the density of distribution inside the component. However, during the sintering process, trapped lubricant is often found to be burnt out hence leaving pores or voids which result in the lower strength of the final products. Warm compaction was initiated in the nineties, however not much information has been published about the effects of lubrication on the quality of the components produced through this route. Therefore, this paper presents the outcome of an experimental investigation about the effects of lubrication on manufacturing near-net shape components through the warm compaction route. Iron powder ASC 100.29 was mixed mechanically with zinc stearate to prepare the feedstock. Mixing time, weight percentage of lubricant content and compaction temperature were varied during green compact generation while sintering temperature, heating rate and holding time were manipulated during sintering. The relative densities and strengths of the final products were investigated at every compaction as well as sintering parameter. The results revealed that lubrication could provide significant effects at the compaction temperature of 180ºC while no significant effect of lubrication was observed during sintering. The suitable lubricant content was found to be 0.4 wt% and mixing time was around 30 min and the sintering temperature was around 990ºC.

Matched MeSH terms: Lubrication
Fulltext Improvement in the mechanical strength of compacted urea fertilizer tablets through die wall lubrication

Intan Soraya Shamsudin, Mohd Shamsul Anuar, Ahmad Husni Mohd. Hanif, Yus Aniza Yusof, Suraya Mohd Tahir

Pertanika Journal of Science & Technology, 2019;27(1):193-203.
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This research was conducted to investigate the compaction performance and mechanical
strength of compacted urea fertilizer in unlubricated and lubricated die systems. The
ground urea 46% N fertilizer was compacted in a 13 mm flat-face cylindrical die set in
both unlubricated and lubricated die systems with vegetable fatty acids and magnesium
stearate as lubricants at various compaction stresses to produce urea fertilizer tablets. In
conclusion, a lubricated die system reduces the frictional effects during the production of
urea fertilizer tablets and also produces a mechanically stronger urea fertilizer tablet than
those produced in an unlubricated die system. In addition, the vegetable fatty acids and
magnesium stearate lubricants are found to improve the compaction performance of urea
fertilizer tablet as well as its mechanical strength.

Matched MeSH terms: Lubrication
Fulltext Laser-Assisted High Speed Machining of 316 Stainless Steel: The Effect of Water-Soluble Sago Starch Based Cutting Fluid on Surface Roughness and Tool Wear

Yasmin F, Tamrin KF, Sheikh NA, Barroy P, Yassin A, Khan AA, et al.

Materials (Basel), 2021 Mar 09;14(5).
PMID: 33803364 DOI: 10.3390/ma14051311

Laser-assisted high speed milling is a subtractive machining method that employs a laser to thermally soften a difficult-to-cut material's surface in order to enhance machinability at a high material removal rate with improved surface finish and tool life. However, this machining with high speed leads to high friction between workpiece and tool, and can result in high temperatures, impairing the surface quality. Use of conventional cutting fluid may not effectively control the heat generation. Besides, vegetable-based cutting fluids are invariably a major source of food insecurity of edible oils which is traditionally used as a staple food in many countries. Thus, the primary objective of this study is to experimentally investigate the effects of water-soluble sago starch-based cutting fluid on surface roughness and tool's flank wear using response surface methodology (RSM) while machining of 316 stainless steel. In order to observe the comparison, the experiments with same machining parameters are conducted with conventional cutting fluid. The prepared water-soluble sago starch based cutting fluid showed excellent cooling and lubricating performance. Therefore, in comparison to the machining using conventional cutting fluid, a decrease of 48.23% in surface roughness and 38.41% in flank wear were noted using presented approach. Furthermore, using the extreme learning machine (ELM), the obtained data is modeled to predict surface roughness and flank wear and showed good agreement between observations and predictions.

Matched MeSH terms: Lubrication
Fulltext Sexual function of malay women with type 2 diabetes mellitus: a preliminary study

Kamaralzaman S, Sidi H, Yau M, Budin SB, Sani A, Mohamed J

ASEAN Journal of Psychiatry, 2010;11(1):64-71.
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Objective: Female sexual dysfunction is a known complication of diabetes mellitus. The aims of this study is to estimate the prevalence of sexual dysfunction and the types of sexual dysfunction experienced by Malay women with type 2 diabetes mellitus.
Methods: Cross sectional study was conducted on married Malay women with type 2 diabetes mellitus, receiving treatment from two community clinics in Selangor, Malaysia. Female sexual function was assessed using Malay version of Female Sexual Function Index.
Results: This study found that sexual dysfunction was present among 18.2% women. Lack of libido was the commonest symptom among these women and was observed in 40.9% of women followed by sexual dissatisfaction (36.4%). Sexual arousal disorder was observed in 22.7%, 18.2% complained of lack of lubrication, and 22.7% had vaginal discomfort. Orgasmic dysfunction was found in only 4.5% of these women.
Conclusion: This preliminary research showed sexual desire disorder was the commonest type of sexual disorder among diabetic women.

Matched MeSH terms: Lubrication
Spontaneous knot formation impeding the removal of a silicone urethral catheter

Mustafa NA, Lope RJ, Cheah FC

Arch. Dis. Child. Fetal Neonatal Ed., 2006 Jul;91(4):F287.
PMID: 16790731
Matched MeSH terms: Lubrication
Fulltext The prevalence of sexual dysfunction among postpartum women on the East Coast of Malaysia

Khalid NN, Jamani NA, Abd Aziz KH, Draman N

J Taibah Univ Med Sci, 2020 Dec;15(6):515-521.
PMID: 33318744 DOI: 10.1016/j.jtumed.2020.08.008

Objective: Sexual health is a key component of the overall health and quality of life of both men and women. Sexual dysfunction is a common condition, but it lacks professional recognition. This study aims to determine the prevalence and types of sexual dysfunctions among postpartum women in primary care clinics and their associated factors in a Malaysian cohort.
Method: In this cross-sectional study, we recruited 420 women from nine primary care clinics in Kuantan, Pahang, Malaysia. All participants had given livebirths within six weeks to six months and had attended either a postnatal or a well-child clinic at a government primary care clinic. The assessment of female sexual dysfunction (FSD) was done using a validated Malay version of the female sexual function index (MVFSFI). Data were statistically analysed using appropriate methods.
Results: More than one-third (35.5%) of women had postpartum sexual dysfunction. The most common types were lubrication disorder 85.6% (n = 113), followed by loss of desire 69.7% (n = 92) and pain disorders 62.9% (n = 83). Satisfaction disorder 7.3% (n = 27), orgasmic disorder 9.7% (n = 56) and arousal disorder 11.0% (n = 41) were less common sexual problems. The independent associated factors for FSD were high education level (adjusted odd ratio = 1.717, 95% CI 1.036-2.844; p

Matched MeSH terms: Lubrication