Natural Lubrication Research Articles

Surface treatments for boriding of Ti6Al4V alloy in view of applications as a biomaterial

Abstract Even if Ti6Al4V has great biocompatibility, it cannot be used for several components of joint implants because of low wear and fretting resistance. This research is focused on improving the bio-tribological characteristics of Ti6Al4V alloy through a surface boriding process. The borided coating was characterized by microstructural and chemical analyses, hardness and adhesion tests. Adsorption of albumin was verified by surface zeta potential vs pH for characterizing interaction with physiological natural lubricants. A heat treatment at temperature near or above the beta transus allows to obtain a performant coating (thickness, hardness, adhesion) even if a change in microstructure of the substrate occurs.

Biolubricant potential of exopolysaccharides from the cyanobacterium Cyanothece epiphytica.

Exopolysaccaharides (EPS) are carbohydrate polymers secreted by microbial cells, as a protective layer termed sheath or capsule. Their composition is variable. Optimisation of nutrient factors and the effect of some simple stresses on the ability of Cyanothece epiphytica to produce EPS were tested. Of the tested stresses, exposure to ozone for 50s at 0.06mg/L resulted in a relatively high EPS yield, without any damage to cell structure. EPS was characterised physicochemically. Chemically, it was found to be composed of pentoses arabinose and xylose; hexoses glucose, galactose and mannose; and the deoxyhexose fucose sugars which were sulphated and with different functional groups. EPS from C. epiphytica was found to be a good hydrophobic dispersant, an excellent emulsifier as well as a flocculant. Its potential as a biolubricant with characteristics better than the conventional lubricant 'grease' was revealed through analysis. This study gave the clue for developing a commercial technology to produce a less expensive and more environment-friendly natural lubricant from the cyanobacterium C. epiphytica for tribological applications.

Preparation and invivo screening of eye wash suspension

Human eyes are precious organs in the body that enable us to see and perceive things. The eyes secrete a natural lubricant called eye tears. This was produced to keep away the exposed part of the eye from microorganisms and other diseases causing microbes and irritants. The eyes are the most sensitive and affected parts when there is a slight change in the irritation level and allergies. Taking this into consideration, the extracts of the plants like Turmeric and Tulsi have been prepared into a suspension that can be used in the eye for its antimicrobial activity and also give the eyes that cooling and lubricating effect. The eye washes that were prepared were investigated for the antibacterial activity and were found effective against the three tested bacteria. They were also proven safe and non-irritant to the eyes.

Physical Characteristics of Tetrahydroxy and Acylated Derivatives of Jojoba Liquid Wax in Lubricant Applications.

Jojoba liquid wax is a mixture of esters of long-chain fatty acids and fatty alcohols mainly C38:2–C46:2. The oil exhibits excellent emolliency on the skin and, therefore, is a component in many personal care cosmetic formulations. The virgin oil is a component of the seed of the jojoba (Simmondsia chinensis) plant which occurs naturally in the Sonora Desert in the United States and northwestern Mexico as well as in the northeastern Sahara desert. The seed contains 50–60% oil by dry weight. The plant has been introduced into Australia, Argentina, and Israel for commercial production of the jojoba oil. As a natural lubricant, we are seeking to explore its potential as a renewable industrial lubricant additive. Thus, we have chemically modified the carbon-carbon double bonds in the oil structure in order to improve its already good resistance to air oxidation so as to enhance its utility as well as its shelf life in nonpersonal care applications. To achieve this goal, we have hydroxylated its –C=C– bonds. Acylation of the resulting hydroxyl moieties has generated short-chain vicinal acyl substituents on the oil which keep the wax liquid, improving its cold flow properties and also protecting it from auto-oxidation and rancidity.

Lamellar slippage of bilayers in natural joints lubrication

Lamellar slippage of bilayers in natural joints lubrication

Open System Tribology in the Wheel–Rail Contact—A Literature Review

The tiny contact zone (approximately 1 cm2) where steel wheel meets steel rail is fundamental to rail transport. This work is a comprehensive presentation of recent research in wheel–rail contact tribology. It stresses that, unlike gears or rolling bearings which are sealed contacts with reduced exposure to the surrounding environment, a wheel–rail contact is an open system that is exposed to dirt and particles as well as to applied and natural lubrication (the latter category includes rain, dew, and biological materials such as leaves). As an open system contact, it also radiates sound and airborne wear particles. These characteristics of an open system underscore the need for special studies of open system tribology. Areas requiring study include airborne particle emissions and the environmental effects of applied lubrication and friction modification. Given that adhesion, wear, and sound and particle emission are closely related in an open system, these should be studied together rather than independently.

Corrosion Inhibition: Investigation of Lanolin Coating on the Corrosion Characteristics of Low Carbon Steel in Simulated Sea Water

There is a high demand for an environmentally friendly and cost-effective corrosion inhibitor. Commercially available lanolin has been used as a biodegradable corrosion inhibitor in addition to being a natural lubricant as a results of its relatively low viscosity. This is very useful particularly for marine steel structural applications. In this investigation, corrosion of lanolin-coated 1018 steel was examined after submerging in a stagnant simulated marine environment. Investigation of microstructure for surface corrosion variation including corrosion rate was carried out on both standard and lanolin-coated 1018 steel specimens. Based on the results obtained in this study, it was concluded that lanolin-treated 1018 steel samples retained lanolin coat during long-term submersion. This is attributed to the preferential lanolin amalgamation that occurred over time. The application of protective coat played an important role in corrosion protection/prevention. Pitting corrosion was dominant in uncoated samples, as expected. SEM-based analysis has demonstrated substantial corrosion attack occurring at the periphery of the standard sample compared to lanolin-coated samples.

Experimental study of using wastewater sludge as a new drag reduction agent.

Siltation is considering as a huge risk to the life and security of dams. Forced to preserve their useful volumes, managers use sediment dredging operations through different techniques. The aim of our work is to investigate the wastewater sludge derived from wastewater treatment as a new natural lubricating instrument during transport of sediment in the pipes and to reduce head losses. From an economic and environmental point of view, this technique is more effective than the use of industrial polymers. The rheological study is done using an RS600 rheometer. Head losses and friction reducing are measured on three horizontal pipes (30, 50 and 80 mm). The mud from the dam and sludge are added at different volumes concentrations. The results revealed that the mud follows the Herschel-Bulkley model at 10-20% volume concentration, even after adding wastewater sludge proportions from 0.1- 0.4%. The mud flow head losses in pipes increase with increasing solids concentration. A maximum reduction in yield stress and frictional head loss are observed at 0.25 to 0.35% of sludge concentration, which can be the most effective choice.

Modulating carbohydrate-based hydrogels as viscoelastic lubricant substitute for articular cartilages

Viscosupplementation is a therapeutic approach for osteoarthritis treatment, where the synovial fluid, the natural lubricant of the joints, is replaced by viscoelastic solutions with rheological properties comparable or better than the starting material. This study presents the development of an innovative platform for viscosupplementation, based on the optimization of polysaccharide-based colloidal hydrogel, aiming to reduce on-site enzyme degradation and enhance the possibility of hyaluronic acid substitution with alternative biomaterials. Catanionic vesicles are proposed as physical crosslinker that can guarantee the formation of a ‘soft’, tunable network, offering a dual-therapeutic approach: on the mechanical relief perspective, as well as on the drug/gene delivery strategy. This research focuses on the fabrication and optimization of colloidal networks, driven by the synergistic interaction among catanionic vesicles and cationic modified cellulose polymers. This study tests the hypothesis that cellulose-like polymers can be arranged into functional matrix, mimicking the mechanical properties of healthy synovial fluids.

Abstract OT3-07-04: A randomized study comparing MoistHer to topical lidocaine for female breast cancer survivors with dyspareunia

Abstract BACKGROUND: Problems related to sexual function are known to affect quality of life in female breast cancer survivors (BCS). A leading symptom of sexual dysfunction reported by BCS is dyspareunia, defined as moderate to severe penetrative pain with intercourse that results in reduced frequency of intercourse or abstinence. Dyspareunia in females is most commonly caused by vaginal dryness and primarily treated with estrogen therapy, a contraindication for many BCS. A recent trial found that estrogen-deficient BCS with dyspareunia who applied topical lidocaine to the vulvar vestibule (VV) prior to penetrative intercourse (PI) reported decreased pain during PI and improvement of sexual distress (Goetsch MF, JCO 2015). Identification of additional non-hormonal therapies to target the VV prior to PI may therefore provide treatment options for the improvement of sexual dysfunction in BCS with dyspareunia. TRIAL DESIGN: This is a double-blind, randomized trial to evaluate the benefits of applying natural lubricant MoistHer (MH) to the VV prior to PI in female BCS with dyspareunia. Subjects must be female ≥18 years BCS without active treatment (except for hormonotherapy), in a stable heterosexual partnership for ≥5 years, and report ≥ 3 months of consistent pain with PI. Patients with a history of pelvic pain, pelvic floor myalgia, vulvar dermatoses, or vaginismus will be excluded. Subjects will be randomized 1:1 to blinded home therapies of either MH or Topical Lidocaine (TL) for application to VV. MH is a commercially available vaginal moisturizer made of emu oil, tocopherol, safflower oil, and aloe extract and will be supplied by manufacturer Dromeo Inc. TL will be a 4% aqueous lidocaine hydrochloride solution prepared by research pharmacist (RP). Both MH and TL will be dispensed by RP in identical unmarked bottles. Subjects will agree to apply study liquid to VV and attempt PI at least twice per week for 4 weeks while maintaining a study diary to record pain scores. Outcomes will be measured via Sexual Function Questionnaire (SFQ), Female Sexual Distress Score-Revised (FSDS-R), and a rating of pain during PI on a scale of zero (no pain) to 10 (worst pain) via Numerical Rating Scale (NRS), to be completed by subjects at baseline, 2 weeks, and 4 weeks. AIMS: Primary endpoint is pain with PI, to be reported as a score on the NRS. Secondary endpoints are improved quality of sexual life and resumption of PI, to be measured by the SFQ and FSDS-R. STATS/TARGET ACCRUAL: A total of 50 patients will be recruited and randomized to receive either MH or TL at a 1:1 ratio (25 per group) using the Pocock-Simon dynamic allocation method. This sample size will achieve 94% power to detect at least 1.5 points NRS mean difference between treatments. NRS change will be compared between the two arms using a two-sample t-test (Pooled Standard error or Satterthwaite approximation as appropriate). Secondary outcomes include the SFQ and FSDS-R for which a longitudinal analysis of subscale scores will be conducted using a generalized linear mixed-effects model with fixed effects for treatment group and time. All statistical analyses will be conducted using SAS 9.3 [SAS Institute Inc., Cary, NC, USA]. Statistical significance will be defined as p < 0.05. Citation Format: Bendinger GM, Baptist S, Alvarez Tapias C, McGuire E, Rados K, Nixon D, Randolph K, McNight JE, Pabbathi H, Panicker R, Johnson AT, Geisler JP, Manahan KJ, Lammersfeld C, Avarez RH. A randomized study comparing MoistHer to topical lidocaine for female breast cancer survivors with dyspareunia [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-07-04.

Genital Sensory Detection Thresholds and Patient Satisfaction With Vaginoplasty in Male-to-Female Transgender Women

IntroductionGender-affirming surgery is common for the treatment of gender dysphoria, but its effect on genital sensitivity is not well known. AimsTo investigate genital sensory detection thresholds in male-to-female transgender women postoperatively and their relation to psychological well-being and variables of satisfaction. MethodsProspective study on 28 transgender women at least 18 years old operated on at least 3 months before the study by a single surgeon (N.M.J.). Main Outcome MeasuresMedical complications; sensory detection thresholds for light touch, pressure, and vibration; and questionnaires on general and sexual satisfaction, sexual function, depression, and psychological well-being. ResultsSensory detection thresholds ranged from 0.07 to 2.82 g for light touch, with the neck being most sensitive; from 20.23 to 34.64 g for pressure, with similar results for the neck and clitoris; and from 0.0052 to 0.0111 V for vibration, with similar findings for all stimulation points. Satisfaction with the appearance of the labia, vulva, clitoris, and sexual function was good to very good. Frequency of sexual activities increased significantly postoperatively for orogenital stimulation and decreased significantly for frequency of fantasies (t = −4.81; P < .0001). Orgasmic function was reported by 80% of participants. Psychological adjustment was good to very good, with low depression scores. Sexual satisfaction was statistically and positively correlated with vaginal function and depth, clitoral sensation, appearance of the vulva and labia minora, and natural lubrication and negatively correlated with depression scores. ConclusionGender-affirming surgery yields good results for satisfaction with appearance and function. Genital sensitivity showed the best results with pressure and vibration.

Light and energy based therapeutics for genitourinary syndrome of menopause: Consensus and controversies.

Gynecologist and plastic surgeons pioneered the application of lasers in medicine and surgery almost 5 decades ago, initially used to treat cervical and vaginal pathologies. Ever since, energy-based devices have been deployed to treat pelvic pathologies and improve fertility. Recent technological developments triggered an unprecedented wave of publications, assessing the efficacy of fractional laser, and radiofrequency on the vaginal wall in reversing natural aging processes. Studies have shown that a certain degree of thermal energy deposited on the vaginal wall stimulates proliferation of the glycogen-enriched epithelium, neovascularization, and collagen formation in the lamina propria, and improves natural lubrication and control of urination. This review aimed to review such data and to guide future research. A unique assembly of experts from around the globe, compiled and edited this manuscript based on a thorough literature review and personal experience. Lasers Surg. Med. 49:137-159, 2017. © 2017 Wiley Periodicals, Inc.

Is Rectosigmoid Vaginoplasty Still Useful?

BackgroundThe ideal vaginoplasty must be successful functionally as well as have a natural appearance, and also must retain its functionality and appearance over the long term. Conventional vaginoplasty techniques have functional limitations and are associated with recurrent complications, but rectosigmoid vaginoplasty is known to have a high satisfaction rate due to its functional similarity with the vagina. We conducted the present study to assess the usability of rectosigmoid vaginoplasty over the course of long-term follow-up.MethodsFrom March 1992 to February 2014, 84 patients were treated with rectosigmoid vaginoplasty; 44 had gender identity disorder, 29 had vaginal agenesis, 8 had female pseudohermaphroditism, and 3 had gynecologic malignancies after radical pelvic surgery. This retrospective study was based on a review of the patients' records, clinical examinations, complications, and questionnaires about appearance, function, and sexual intercourse.ResultsAll patients who underwent rectosigmoid vaginoplasty were discharged within 2 weeks without surgical flap loss. The early complications were partial flap necrosis, difficulty in defecation, mucous hypersecretion, and postoperative ileus. The late complications were vaginal introitus contracture, vaginal prolapse, and difficulty in urination. The mean length and diameter of the neovagina 3.4 years after rectosigmoid vaginoplasty were 13.2 cm and 3.8 cm, respectively. On questionnaires about satisfaction, 70% of patients reported excellent satisfaction, 11% good, 12% fair, and 7% poor.ConclusionsRectosigmoid vaginoplasty is useful, safe, and well-accepted operative method with good functional and cosmetic results, such as natural lubrication and adequate vaginal length and width obtained without requiring the use of a dilator.

Wear behaviour of UHMWPE reinforced by carbon nanofiller and paraffin oil for joint replacement

The majority of artificial joints incorporate biomedical grade Ultra High Molecular Weight Poly Ethylene (UHMWPE), whose wear is considered most important in controlling service time of the whole joint. The aim of this work was to improve wear resistance of UHMWPE through the addition of 0.5–2.0wt% of Carbon Nano Filler (CNF) and 2% wt of Paraffin Oil (PO) using ball milling (BM) and extrusion techniques (EX). The wear tests on these nanocomposites were conducted by a pin on disc in dry (air) and wet media (simulated synovial fluid or artificial lubricant, and bovine synovial fluid or natural lubricant). Mechanical tests (tensile and hardness), physical analysis (calorimetric, density, wet ability, roughness) and morphological observations were also performed. The experimental results showed that natural lubricant provides the greatest reduction in wear rate while the largest one occurred in air. Furthermore, the BM mixed nanocomposites with a filler load of 1.0% exhibited the best wear resistance among all the samples with an improvement of 42%, 64% and 83% in air, artificial and natural lubricant, respectively. This is due to its higher ductility and thermal features, and lower wet ability in the two lubricants.

Potential Synthetic Biolubricant as an Alternative to Bovine Serum

It is crucial that orthopaedic implant materials are tested in conditions that replicate the natural body’s environment as closely as possible. Bovine serum is currently recommended for use by the International Organisation for Standardisation (ISO) for the wear testing of these implant materials, however, the rheological properties of bovine serum do not match fully those of the body’s natural lubricant, synovial fluid. This study looks at a potential alternative to bovine serum for the testing of orthopaedic implant materials; 0.5% gellan gum fluid gel. Wear tests using multidirectional motion were conducted on ultra-high molecular weight polyethylene (UHMWPE) pins rubbing against stainless steel plates. Roughness measurements were performed during testing along with particle analysis of the testing lubricant. At two million cycles (equivalent to 121.3 km of sliding), the mean wear factor for the four UHMWPE pins was 0.25 (standard deviation (SD) 0.03) × 10−6 mm3/Nm and there was no evidence of any transfer film on the plate surfaces. The wear factor produced by 0.5% gellan gum fluid gel was lower than that measured in previous studies using bovine serum as the lubricant but greater than the wear factor shown in published work using a similar alternative lubricant (sodium alginate mixed with gellan gum). Work on the development of a suitable alternative lubricant to bovine serum will continue.

True Stability of Lubricants Determined Using the Ball-on-Disk Test

True stability of lubricants can be determined when there is minimum change in the contact area and also the intervention of wear debris in the contact zone. Here, we have used the ball-on-disk instrument with the migrating point contact, that is, relative motion between the ball and disk condition to fix the contact area and minimize the wear debris at the contact zone. The jump in the friction coefficient indicates the film failure, which appeared earlier for the motor oil 5W30 compared to 5W40. Such profile was not recorded in absence of relative motion. Therefore, 5W40 was considered to have a better lubricant stability than 5W30. Applying the same test condition to the natural lubricants shows that glycerol has better lubricant stability than glycerol-water mixture. Superior true lubricant stability by glycerol and 5W40 can be related to its high viscosity. However, they were less wear resistant compared to low viscosity lubricants like 5W30 and glycerol-water. We suspect the role of microscopic wear debris at the contact zone for this behavior although it should have been avoided in the migrating point contact condition. Overall, ball-on-disk instrument with a migrating point contact condition is an effective technique to determine the stability of lubricants.

Application of recent advances in hydrodynamic methods for characterising mucins in solution.

Mucins are the primary macromolecular component of mucus--nature's natural lubricant--although they are poorly characterised heterogeneous substances. Recent advances in hydrodynamic methodology now offer the opportunity for gaining a better understanding of their solution properties. In this study a combination of such methods was used to provide increased understanding of a preparation of porcine intestinal mucin (PIM), MUC2 mucin, in terms of both heterogeneity and quantification of conformational flexibility. The new sedimentation equilibrium algorithm SEDFIT-MSTAR is applied to yield a weight average (over the whole distribution) molar mass of 7.1 × 10(6) g mol(-1), in complete agreement with size exclusion chromatography coupled with multi-angle light scattering (SEC-MALS), which yielded a value of 7.2 × 10(6) g mol(-1). Sedimentation velocity profiles show mucin to be very polydisperse, with a broad molar mass distribution obtained using the Extended Fujita algorithm, consistent with the elution profiles from SEC-MALS. On-line differential pressure viscometry coupled to the SEC-MALS was used to obtain the intrinsic viscosity [η] as a function of molar mass. These data combined with sedimentation coefficient data into the global conformation algorithm HYDFIT show that PIM has a flexible linear structure, with persistence length L p ~10 nm and mass per unit length, M L ~2380 g mol(-1) nm(-1), consistent with a Wales-van Holde ratio of ~1.2 obtained from the concentration dependence of the sedimentation coefficient.

A Current Scenario and Novel Approaches to Degrade the Lignocellulosic Biomass for the Production of Biodiesel

Biofuels derived from lignocellulose biomass are alternative options replacing fossil fuels in near future. Lignocellulose biomass consists of lignin, cellulose and hemicelluloses. These three elements form a complex network in lignocellulose biomass which is difficult to break by following traditional methods because of lignin. Pretreatment technologies makes possible to degrade the main barrier ie lignin.The possible pretreatment approaches are: organic solvent-water mixture, natural dyes, nanocatalyst, Ionic Liquids (ILs) treatments and combinational culture of bacterial strains i.e. Bacillus and Geobacillus species efficently produces biofuel via transesterification. Currently, the production of biofuels across the world has increased especially in U.S, India and other European countries. On account of following reasons: ecofriendly residues, less expensive and natural lubricant makes biofuels are better fuel for future generation. Furthermore, some important key policy actions have been discussed in article.

New Design Concept for Reducing Torque Wear on Implant

The hip (coxofemoral) joint is built so as to provide, at the same time, maximum stability and mobility, and is characterized by a very low wear rate and very low frictional forces thanks to the very good natural lubrication. In time, due to various reasons such as aging, joint illnesses, bone tumors, arthritis, injuries, coxofemoral joints may lose their self-lubrication ability, causing pains that make movement almost impossible. The therapeutic solution for coxofemoral joint illnesses is hip implant arthroplasty. Medical implants replacing the bone segments of coxofemoral joints are subjected to mechanical stress during walking and daily activities, which leads to wear in the long run. In the (most frequent) case of a bipolar hip implant, consisting of a femoral stem and femoral head, the area most affected by wear is the hip implant coupling, which represents the connection between the sphere-shaped proximal end of the femoral stem and the femoral head’s ball groove. Typically, the spherical proximal end of the femoral stem is made of metallic biomaterials (titanium and titanium alloys, cobalt-based alloys, stainless steels) or ceramic biomaterials (alumina, zirconia), while the femoral head’s ball groove is made of polymeric biomaterials (high-density polyethylene), metallic biomaterials or ceramic biomaterials. In the hip implant’s coupling there takes place a sliding friction whose coefficient depends on the nature of the touching surfaces (metal on metal, metal on polyethylene, ceramic on polyethylene, ceramic on ceramic). The wear that occurs in the coupling is due especially to the particles of material detached from the surfaces coming into contact. A worn coupling should be replaced by a revision surgery that the patient must go through, since loose particles generate severe joint inflammation. The objective of this paper is: -to point out the wear degree of the components forming the friction coupling of a hip implant, by presenting images, as seen on a video microscope, of two implants retrieved from patients after revision surgery -to present a new structural option for the construction of a hip implant coupling, by introducing two ball cages that replace the femoral head’s ball groove, which reduces the contact surface and replaces sliding friction with rolling friction (with a lower friction coefficient), thus diminishing the wear on the implant coupling.

Enhanced lubrication on tissue and biomaterial surfaces through peptide-mediated binding of hyaluronic acid.

Lubrication is key for the efficient function of devices and tissues with moving surfaces, such as articulating joints, ocular surfaces and the lungs. Indeed, lubrication dysfunction leads to increased friction and degeneration of these systems. Here, we present a polymer-peptide surface coating platform to non-covalently bind hyaluronic acid (HA), a natural lubricant in the body. Tissue surfaces treated with the HA-binding system exhibited higher lubricity values and in vivo were able to retain HA in the articular joint and to bind ocular tissue surfaces. Biomaterials-mediated strategies that locally bind and concentrate HA could provide physical and biological benefits when used to treat tissue-lubricating dysfunction and coat medical devices.