Application of high-performance liquid chromatography in determining saturates and aromatic hydrocarbons along with polars/additives in automotive finished and used lubricating oils.

Lubricating oils help an internal combustion engine function effectively by reducing friction and wear on the engine's moving parts. They typically consist of petroleum-derived base oil and various additives to achieve the desired characteristics in automotive engine oils. Determination of aromatics and polar additives in the finished and used lubricating oils is not possible with existing methods hence their development is significant from the perspectives of environment and reuse/re-refining of used lubricating oils. This study reports the development of a new HPLC method to determine additives in the finished lubricating oils and/or polars in the used engine oils. The proposed method is simple, fast (runtime of 13 min), does not require sample pre-treatment, and exhibits high precision and superior limits of detection and quantification. The method demonstrated good linear response ranging from 0.1 to 30 mass for total aromatics and 0.1 to 20 % for additives. The method validation was carried out by analyzing brand-new commercial two and four-wheeler lubricants with used automotive lubricants. Based on the proposed method, the aromatics and additives concentration ranges in the studied finished lubricants were estimated between 0.20-1.70 % (mass) and 0.20-3.50 % (mass), respectively. Similarly, for used lubricants, the aromatics and additives were estimated to be 1.00-6.10 % and 0.60-2.40 % (mass), respectively.

A review on properties, challenges and commercial aspects of eco-friendly biolubricants productions.

Lubricants operate as antifriction media, preserving machine reliability, facilitating smooth operation, and reducing the likelihood of frequent breakdowns. The petroleum-based reserves are decreasing globally, leading to price increases and raising concerns about environmental degradation. The researchers are concentrating their efforts on developing and commercializing an environmentally friendly lubricant produced from renewable resources. Biolubricants derived from nonedible vegetable oils are environmentally favorable because of their non-toxicity, biodegradability, and close to net zero greenhouse gas emissions. The demand for bio lubricants in industry and other sectors is increasing due to their non-toxic, renewable, and environmentally friendly nature. Good lubrication, anti-corrosion, and high flammability are characteristic properties of vegetable oils due to their unique structure. This study presents several key properties of nonedible oils that are used to produce lubricants via the transesterification process. Bibliometric analysis is also performed, which provides us with a better understanding of previous studies related to the production of bio lubricants from the transesterification process. Only 371 published documents in the Scopus database were found to relate to the production of bio lubricants using the transesterification process. The published work was mostly dominated by research articles (286; 77.088%). Significant development can be seen in recent years, with the highest occurrence in 2021, reaching 68 publications accounting for 18.38% of the total documents. In the second step, (i) the authors with the most number of publications; (ii) journals with the most productions; (iii) most productive countries; and (iv) the authors' most frequently used keywords were evaluated. These results will provide a pathway for researchers interested in this field. Lastly, recommendation is made on research gaps to device possible strategies for its commercialization.

On-Demand Maneuvering of Diverse Prodrug Liquids on a Light-Responsive Candle-Soot-Hybridized Lubricant-Infused Slippery Surface for Highly Effective Toxicity Screening.

At present, microscale high-throughput screening (HTS) for drug toxicity has drawn increased attention. Reported methods are often constrained by the inability to execute rapid fusion over diverse droplets or the inflexibility of relying on rigid customized templates. Herein, a light-responsive candle-soot-hybridized lubricant-infused slippery surface (CS-LISS) was reported by one-step femtosecond laser cross-scanning to realize highly effective and flexible drug HTS. Due to its low-hysteresis merits, the CS-LISS can readily steer diverse droplets toward arbitrary directions at a velocity over 1.0 mm/s with the help of tracing lateral near-infrared irradiation; additionally, it has the capability of self-cleaning and self-deicing. Significantly, by integrating the CS-LISS with a GFP HeLa cell chip, high-efficiency drug toxicity screening can be successfully achieved with the aid of fluorescence imaging. This work provides insights into the design of microscale high-throughput drug screening.

Microwave-assisted synthesis of trimethylolpropane triester (bio-lubricant) from camelina oil.

Vegetable oils, whose hydrocarbon structure is very similar to that of petroleum products, are ideal renewable and sustainable alternatives to petroleum lubricants. Bio-lubricants are commonly synthesized by modifying the chemical structure of vegetable oils. In this study, microwave irradiation was applied to intensify the mass-transfer-limited transesterification reaction to produce trimethylolpropane triester (bio-lubricant) from camelina oil as a promising local energy crop. A rotatable RSM-BBD method was applied to find the optimal levels of experimental factors, namely reaction time (67.8 min), the catalyst concentration (1.4 wt%) and the molar ratio (3.5). In these optimal levels, the reaction yield of 94.3% was obtained with desirability of 0.975. The quadratic statistical model with a determination coefficient of 97.97%, a standard deviation of 0.91 and a variation coefficient of 1% was suggested as the most appropriate model by Design-Expert software. Finally, the physicochemical properties of the purified product were in accordance with the requirements of the ISO-VG22 base oil standard.

A bibliometric analysis on the tribological and physicochemical properties of vegetable oil-based bio-lubricants (2010-2021).

Vegetable oil-based bio-lubricants possess potential as an alternative to mineral oil-based lubricants due to their biodegradability and renewability. However, a detailed examination of the publication focus, trend, and future direction related to these bio-lubricants' tribological and physicochemical properties is scarce. Therefore, the study presents a bibliometric analysis of vegetable oil-based bio-lubricant. One hundred sixty-five publications were extracted from Web of Science (WoS) from 2010 to 2021. During this period, the total citation was 2,240, recording an average citation per publication of 13.58. Proceedings of The Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology was the top productive journal, publishing 10.3% of the publications selected on the studied topic. From 2010 to 2021, India was the most productive country working on bio-lubricants due to its abundance of coconut products, followed by Malaysia due to its abundance of palm products. The keyword analysis indicated that a significant amount of work emphasised the derivation of bio-lubricants with an increasing shift towards tribological performance characterisation. From the analysis, palm is the most studied bio-lubricant, followed by castor oil. The reported viscosity and viscosity index values cover an extensive range, allowing these bio-lubricants to be adopted for a wide range of applications. For different vegetable oil-based bio-lubricants, the coefficient of friction is reported from 0.001 to 0.78, with the wear scar diameter being reported from 0.075 µm to 4.59 mm. Even though these bio-lubricants' friction and wear performances can be tabulated, the dataset is still unreliable for lubricant-selection purposes because of the varying test conditions. Such a scenario also limits the ability to correlate the role of fatty acid composition in the vegetable oil-based bio-lubricants in fulfilling their various application-specific potentials. Therefore, this study recommends that a unified correlation between the fatty acid composition and its tribological performance be attained consistently to better elucidate the potential of vegetable oil-based bio-lubricants.

Separation and determination of the group-type composition of modern base and lubricating oils with a wide range of polarity, especially emitted to the environment.

Lubricating oils are composed of base oils (>85% v/v) and enriching additives (<15% v/v). Three types of base oils may be distinguished: 1) traditional bases (obtained by low-volatile fractions from crude oil distillation refining), 2) synthetic bases (mainly poly-alpha-olefins, sometimes esters, especially succinic acid esters), 3) bases of natural origin (especially obtained from refined plant oils). The bases of natural origin are the only ones recommended for application when lubricating oil may be emitted to the environment (e.g. when the machine with an open cutting system is used). Group-type separation and analysis of group-type composition of base and lubricating oils are of significant importance in quality control and environmental monitoring. Due to the potentially wide range of polarity of the components of base and lubricating oils, group- type separation becomes a difficult separation problem. It is also a serious analytical problem due to the considerable diversity of physicochemical properties. The authors propose a new procedure for the separation and determination of the group-type composition of base and lubricating oils using thin-layer liquid chromatography in normal phase systems (abr. NP-TLC) on silica gel plates impregnated with berberine salt/in the coupling of thin-layer chromatography with flame ionization detection (abr. TLC-FID). A new, effective procedure of TLC plates impregnation with berberine sulphate was presented. The proposed procedure ensures the visualization of all groups of base oils. Extensive experimental research showed that a 2-step development procedure with application of n-hexane up to 100% height of development +15 min and further n-hexane: isopropanol: tri-fluoroacetic acid 96.25: 3: 0.75 (v: v: v) up to 75% height of development is advantageous for the group-type separation, both in TLC-FID and TLC.

Extraction and Characterization of Sesbania cannabina (Retz.) Pers. (Dhaincha) Seed Oil for Potential Engineering Applications.

Sesbania cannabina (Retz.) Pers. (Dhaincha) is a member of family Fabaceae spread over several countries in tropical and subtropical regions of the world. Sesbania aculeata, Sesbania drummondii, Sesbania grandiflora, Sesbania rostrata, Sesbania sesban, and Sesbania speciosa are other members of this family. The agricultural, nutritional and pharmaceutical applications of Sesbania species are known to farmers, villagers, and the tribes since ages and are well studied by researchers. However, the significance of Sesbania as an industrial crop has not been recognized till now. The objective of this study was extraction and characterization of Sesbania cannabina seed oil (SCSO) for potential engineering applications. The seed oil was extracted with hexane in a Soxhlet extractor. Yield was only 2.32% w/w due to long storage at high temperature in seed house. Sesbania cannabina seed oil methyl ester (SCSOME) was prepared via esterification and transesterification for analysis of fatty acid composition of extracted oil. SCSO has high iodine value (118 g I2/100 g) and high saponification value (185.79 mg KOH/g) making the oil suitable for use as candle stocks or in soap making. However, these applications were ruled out on account of being insignificant for oil available in limited quantity. The oil has high viscosity index (174.19), high onset (382°C) and offset (450°C) decomposition temperatures, endothermic nature, and shear rate thickening behaviour. These properties make SCSO a good candidate for application as specialty lubricant required under severe operating conditions of high temperature and high shear rate or as insulating and cooling transformer oil.

Electrospun lignin-PVP nanofibers and their ability for structuring oil.

This work explores the electrospinnability of low-sulfonate Kraft lignin (LSL)/polyvinylpyrrolidone (PVP) solutions in N,N-dimethylformamide (DMF) and the ability of the different micro- and nano-architectures generated to structure castor oil. LSL/PVP solutions were prepared at different concentrations (8-15 wt%) and LSL:PVP ratios (90:10-0:100) and physico-chemically and rheologically characterized. The morphology of electrospun nanostructures mainly depends on the rheological properties of the solution. Electrosprayed nanoparticles or micro-sized particles connected by thin filaments were obtained from solutions with low LSL/PVP concentrations and/or high LSL:PVP ratios, whereas beaded or bead-free nanofibers were produced by increasing concentration and/or decreasing LSL:PVP ratio, due to enhanced extensional viscoelastic properties and non-Newtonian characteristics. Electrospun LSL/PVP nanofibers are able to form oleogels by simply dispersing them into castor oil at concentrations between 10 and 30 wt%. The rheological properties of the oleogels may be tailored by modifying the LSL:PVP ratio and nanofibers content. The potential application of these oleogels as bio-based lubricants was also explored in a tribological cell. Satisfactory friction and wear results are achieved when using oleogels structured by nanofibers mats with enhanced gel-like properties as lubricants. Overall, electrospinning of lignin/PVP solutions can be proposed as a simple and effective method to produce nanofibers for oil structuring.

Prospects and Challenges of Microwave-Combined Technology for Biodiesel and Biolubricant Production through a Transesterification: A Review.

Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.

Immobilization of Eversa® Transform via CLEA Technology Converts It in a Suitable Biocatalyst for Biolubricant Production Using Waste Cooking Oil.

The performance of the previously optimized magnetic cross-linked enzyme aggregate of Eversa (Eversa-mCLEA) in the enzymatic synthesis of biolubricants by transesterification of waste cooking oil (WCO) with different alcohols has been evaluated. Eversa-mCLEA showed good activities using these alcohols, reaching a transesterification activity with isoamyl alcohol around 10-fold higher than with methanol. Yields of isoamyl fatty acid ester synthesis were similar using WCO or refined oil, confirming that this biocatalyst could be utilized to transform this residue into a valuable product. The effects of WCO/isoamyl alcohol molar ratio and enzyme load on the synthesis of biolubricant were also investigated. A maximum yield of around 90 wt.% was reached after 72 h of reaction using an enzyme load of 12 esterification units/g oil and a WCO/alcohol molar ratio of 1:6 in a solvent-free system. At the same conditions, the liquid Eversa yielded a maximum ester yield of only 34%. This study demonstrated the great changes in the enzyme properties that can be derived from a proper immobilization system. Moreover, it also shows the potential of WCO as a feedstock for the production of isoamyl fatty acid esters, which are potential candidates as biolubricants.

Environmentally friendly processes from coffee wastes to trimethylolpropane esters to be considered biolubricants.

In this study, an eco-friendly renewable biodegradable alternative to petroleum-based oil lubricants was produced using espresso coffee wastes. Waste coffee oil used as raw material was extracted from Espresso coffee wastes by Soxhlet and conventional solvent extraction. Free fatty acids (FFA) were obtained by hydrolysis of the obtained waste oil using Lipozyme TL IM (Thermomyces lanuginosus). The byproduct, glycerol, was also separated from the reaction medium using a separatory funnel. The obtained FFA was used as a raw material in the production of TMP esters. Polyol esters of fatty acids were synthesized as a result of the esterification reaction between FFA and polyol alcohol (trimethylolpropane (TMP)) using Novozyme 435 (Candida antarctica). The amount of FFA in the medium and the FFA conversion was determined by titration with NaOH solution according to ASTM D 5555-95 standard and the FFA composition of espresso coffee oil by GC. The oil content of espresso coffee extract was found to be rich by 16% and the FFA composition was rich in palmitic acid (C16:0 43% by weight) and linoleic acid (C18:2 31% by weight). 31% of FFA was obtained from the coffee oil. Experimental studies have shown that the highest FFA conversion of 88% with 93% TMP tri-ester content was obtained at a temperature of 55°C, 5% enzyme (w/w), non-aqueous media, 3/1 FFA/TMP mole ratio, 500 rpm mixing speed and 24 hours. Implications: Filter coffee wastes, which have become one of the most important biological wastes with an annual production capacity of 6 million tons worldwide; It is targeted to be transformed into environmentally friendly products, as it is important in terms of economy and policies of many developing countries, it is a renewable resource and there is a high amount of waste accumulation day by day. Evaluation of waste filter coffees and oils with this research article; It is envisaged that the bio-lubricating oil used in many sectors will be synthesized and commercialized with an environmentally friendly process.

Correlations between surface composition and aerosolization of jet-milled dry powder inhaler formulations with pharmaceutical lubricants.

Co-jet-milling drugs and lubricants may enable simultaneous particle size reduction and surface coating to achieve satisfactory aerosolization performance. This study aims to establish the relationship between surface lubricant coverage and aerosolization behavior of a model drug (ciprofloxacin HCl) co-jet-milled with lubricants [magnesium stearate (MgSt) or l-leucine]. The co-jet-milled formulations were characterized for particle size, morphology, cohesion, Carr's index, and aerosolization performance. The surface lubricant coating was assessed by probing surface chemical composition using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (ToF-SIMS). The effects of co-jet-milling on the surface energy and in vitro dissolution of ciprofloxacin were also evaluated. Our results indicated that, in general, the ciprofloxacin co-jet-milled with l-leucine at >0.5% w/w showed a significant higher fine particle fraction (FPF) compared with the ciprofloxacin jet-milled alone. The FPF values plateau at or above 5% w/w for both MgSt and l-leucine. We have established the quantitative correlations between surface lubricant coverage and aerosolization in the tested range for each of the lubricants. More importantly, our results suggest different mechanisms to improve aerosolization for MgSt-coating and l-leucine-coating, respectively: MgSt-coating reduces inter-particulate interactions through the formation of low surface energy coating films, while l-leucine-coating not only reduces the surface energy but also creates rough particle surfaces that reduce inter-particulate contact area. Furthermore, surface coatings with 5% w/w MgSt (which is hydrophobic) did not lead to substantial changes in in vitro dissolution. Our findings have shown that the coating structure/quality and their effects could be highly dependent on the process and the coating material. The findings from this mechanistic study provide fundamental understanding of the critical effects of MgSt and l-leucine surface coverages on aerosolization and powder flow properties of inhalation particles.

Non-edible vegetable oil-based feedstocks capable of bio-lubricant production for automotive sector applications-a review.

Fossil fuel resource is on the draining stage which leads to an increment in the cost of the petroleum products. Nowadays, research is focused on the development of environment-friendly lubricants which are derivatives of renewable sources. Bio-lubricants based on non-edible oil sources are environmentally friendly because they are non-hazardous and biodegradable and no emission of toxic gases were detected when they are used. This study involves the characterizations and advantages, as well as utilization of inedible plant oil-driven bio-lubricants as an alternative for tribological applications. This report also presents the status of the global lubricant market as well as the potential outlook of the bio-lubricants for their future usage. Non-edible plant oil-driven bio-lubricants bear high viscosity, high lubricity, and high viscosity index which can enhance the equipment service life and deserve the ability to carry the high load and results in a minimum amount of metal traces during combustion while applied to engines. Beside their advantages, some of the disadvantages are also there which can be addressed by the employment of certain additives available according to the applications. The detailed study about the different additives utilized during their use in the internal combustion engine is also described in detail during this study. This study provides a detailed description of the possibilities associated with bio-lubricant based on non-edible oil feedstocks to the automotive sector applications.

Experimental investigation of tribological characteristics and emissions with nonedible sunflower oil as a biolubricant.

Plant (vegetable) oil has been evaluated as a substitute for mineral oil-based lubricants because of its natural and environmentally friendly characteristics. Availability of vegetable oil makes it a renewable source of bio-oils. Additionally, vegetable oil-based lubricants have shown potential for reducing hydrocarbon and carbon dioxide (CO2) emissions when utilized in internal combustion (IC) engines and industrial operations. In this study, sunflower oil was investigated to study its lubricant characteristics under different loads using the four-ball tribometer and the exhaust emissions were tested using a four-stroke, single-cylinder diesel engine. All experimental works conformed to American Society for Testing and Materials standard (ASTM D4172-B). Under low loads, sunflower oil showed adequate tribological characteristics (antifriction and antiwear) compared with petroleum oil samples. The results also demonstrated that the sunflower oil-based lubricant was more effective in reducing the emission levels of carbon monoxide (CO), CO2, and hydrocarbons under different test conditions. Therefore, sunflower oil has the potential to be used as lubricant of mating components.Implications: An experimental investigation of the characteristics of nonedible sunflower oil tribological behaviors and potential as a renewable source for biofluids alternative to the petroleum oils was carried out. The level of emissions of a four-stroke, single-cylinder diesel engine using sunflower oil as a biolubricant was evaluated.

Designing Lubricating Properties of Vegetable Base Oils.

Lubricants that are based on renewable raw materials have drawn increased attention in various applications, especially those related to the food industry. Due to the high requirements of environmental protection, there is a need to develop biodegradable base oils that are environmentally friendly and do not contain harmful components. The objective of the research was to obtain a base oil with a certain viscosity and certain desired lubricating properties. Base oils were obtained from Crambe abyssinica oil by means of blending with synthetic oil and oxidation. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without CO2 as a solvent. As a final result of this study, oil bases meeting the viscosity requirements and showing suitable lubricating properties were obtained. The Raman spectra of the obtained oils were evaluated.

Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil.

Karanja oil (KO) is widely used for synthesis of bio-fuel karanja oil methyl ester (KOME) due to its competitive price, good energy values and environmentally friendly combustion properties. Bio-lubricant is another value added product that can be synthesized from KO via chemical modification. In this work karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant was synthesized and evaluated for its viscous flow behaviour. A comparison of viscous flow behaviours of natural KO and synthesized bio-fuel KOME and bio-lubricant KOTMPE was also made. The aim of this comparison was to validate the superiority of KOTMPE bio-lubricant over its precursors KO and KOME in terms of stable viscous flow at high temperature and high shear rate conditions usually encountered in engine operations and industrial processes. The free fatty acid (FFA) content of KO was 5.76%. KOME was synthesized from KO in a two-step, acid catalyzed esterification followed by base catalyzed transesterification, process at 65°C for 5 hours with oil-methanol ratio 1:6, catalysts H2SO4 and KOH (1 and 1.25% w/w KO, respectively). In the final step, KOTMPE was prepared from KOME via transesterification with trimethylolpropane (TMP) at 150°C for 3 hours with KOME-TMP ratio 4:1 and H2SO4 (2% w/w KOME) as catalyst. The viscosity versus temperature studies were made at 0-80°C temperatures in shear rate ranges of 10-1000 s-1 using a Discovery Hybrid Rheometer, model HR-3 (TA instruments, USA). The study found that viscosities of all three samples decreased with increase in temperature, though KOTMPE was able to maintain a good enough viscosity at elevated temperatures due to chemical modifications in its molecular structure. The viscosity index (VI) value for KOTMPE was 206.72. The study confirmed that the synthesized bio-lubricant KOTMPE can be used at high temperatures as a good lubricant, though some additives may be required to improve properties other than viscosity.

Lubricant based determination of design space for continuously manufactured high dose paracetamol tablets.

The objective of this study was to devise robust and stable continuous manufacturing process settings, by exploring the design space after an investigation of the lubrication-based parameters influencing the continuous direct compression tableting of high dose paracetamol tablets. Experimental design was used to generate a structured study plan which involved 19 runs. The formulation variables studied were the type of lubricant (magnesium stearate or stearic acid) and its concentration (0.5, 1.0 and 1.5%). Process variables were total production feed rate (5, 10.5 and 16kg/h), mixer speed rpm (500, 850 and 1200rpm), and mixer inlet port for lubricant (A or B). The continuous direct compression tableting line consisted of loss-in-weight feeders, a continuous mixer and a tablet press. The Quality Target Product Profile (QTPP) was defined for the final product, as the flowability of powder blends (2.5s), tablet strength (147N), dissolution in 2.5min (90%) and ejection force (425N). A design space was identified which fulfilled all the requirements of QTPP. The type and concentration of lubricant exerted the greatest influence on the design space. For example, stearic acid increased the tablet strength. Interestingly, the studied process parameters had only a very minor effect on the quality of the final product and the design space. It is concluded that the continuous direct compression tableting process itself is insensitive and can cope with changes in lubrication, whereas formulation parameters exert a major influence on the end product quality.

Determination of the aromatic hydrocarbon to total hydrocarbon ratio of mineral oil in commercial lubricants.

A method was developed to determine the aromatic hydrocarbon to total hydrocarbon ratio of mineral oil in commercial lubricants; a survey was also conducted of commercial lubricants. Hydrocarbons in lubricants were separated from the matrix components of lubricants using a silica gel solid phase extraction (SPE) column. Normal-phase liquid chromatography (NPLC) coupled with an evaporative light-scattering detector (ELSD) was used to determine the aromatic hydrocarbon to total hydrocarbon ratio. Size exclusion chromatography (SEC) coupled with a diode array detector (DAD) and a refractive index detector (RID) was used to estimate carbon numbers and the presence of aromatic hydrocarbons, which supplemented the results obtained by NPLC/ELSD. Aromatic hydrocarbons were not detected in 12 lubricants specified for use for incidental food contact, but were detected in 13 out of 22 lubricants non-specified for incidental food contact at a ratio up to 18%. They were also detected in 10 out of 12 lubricants collected at food factories at a ratio up to 13%. The centre carbon numbers of hydrocarbons in commercial lubricants were estimated to be between C16 and C50.

Influence of bio-lubricants on the orthodontic friction.

The Friction force of Stainless Steel (SS) and Nickel-Titanium (Ni-Ti) rectangular archwires against stainless steel brackets was investigated. Two types of brackets were used namely: Self-ligating brackets (SLB) and conventional brackets (CB). The friction tests were conducted on an adequate developed device under dry and lubricated conditions. Human saliva, olive oil, Aloe Vera oil, sesame oil and sunflower oil were used as bio-lubricants. The friction force was examined as a function of the ligation method and oil temperature. It is found that under oil lubrication, the friction behavior in the archwire/bracket assembly were the best. The SLB ligation was better than the conventional ligation system. The enhancement of the frictional behavior with natural oils was linked to their main components: fatty acids.

A Comparative Study Between an Oil-in-Water Emulsion and Nonlipid Eye Drops Used for Rewetting Contact Lenses.

OBJECTIVES: The purpose of this study was to determine the clinical impact of using SYSTANE BALANCE Lubricant Eye Drops (Alcon, Fort Worth, TX), an oil-in-water emulsion, as a rewetting eye drop in symptomatic contact lens wearers. METHODS: Subjects who had previously experienced contact lens discomfort (CLD), with a mean lens wearing history of 18.6±12.8 years, were randomly assigned to use a Test (SYSTANE BALANCE Lubricant Eye Drops; n=76) or control (habitual nonlipid contact lens rewetting eye drop; n=30) drop over their contact lenses within 5 min of lens insertion and then subsequently at 2 hr intervals up to a maximum of 4 drops per eye daily for a 1-month period. Assessments of subjective comfort, comfortable wearing time, lid wiper epitheliopathy (LWE), and corneal staining were conducted at baseline and after 1 month, after 6 hr of lens wear. RESULTS: Comfort, wearing time, LWE, and corneal staining all showed statistically significant improvements in the test group using SYSTANE BALANCE Lubricant Eye Drops at the 1-month visit compared with baseline data (all P<0.01) and compared with the control group at the 1-month visit (P<0.01, P=0.01, P<0.01, and P=0.03, respectively). CONCLUSIONS: The use of SYSTANE BALANCE Lubricant Eye Drops as a rewetting drop in a group of wearers who experienced symptoms of CLD improved subjective comfort scores, increased comfortable wearing time, and reduced signs of LWE and corneal staining, when compared with the use of non-lipid-containing contact lens rewetting eye drops.