Unique ice dendrite morphology on state-of-the-art oil-impregnated surfaces.

Due to its multifaceted impact in various applications, icing and ice dendrite growth has been the focus of numerous studies in the past. Dendrites on wetting (hydrophilic) and nonwetting (hydrophobic) surfaces are sharp, pointy, branching, and hairy. Here, we show a unique dendrite morphology on state-of-the-art micro/nanostructured oil-impregnated surfaces, which are commonly referred to as slippery liquid-infused porous surfaces or liquid-infused surfaces. Unlike the dendrites on traditional textured hydrophilic and hydrophobic surfaces, the dendrites on oil-impregnated surfaces are thick and lumpy without pattern. Our experiments show that the unique ice dendrite morphology on lubricant-infused surfaces is due to oil wicking into the porous dendritic network because of the capillary pressure imbalance between the surface texture and the dendrites. We characterized the shape complexity of the ice dendrites using fractal analysis. Experiments show that ice dendrites on textured oil-impregnated surfaces have lower fractal dimensions than those on traditional lotus leaf-inspired air-filled porous structures. Furthermore, we developed a regime map that can be used as a design guideline for micro/nanostructured oil-impregnated surfaces by capturing the complex effects of oil chemistry, oil viscosity, and wetting ridge volume on dendrite growth and morphology. The insights gained from this work inform strategies to reduce lubricant depletion, a major bottleneck for the transition of micro/nanostructured oil-impregnated surfaces from bench-top laboratory prototypes to industrial use. This work will assist the development of next-generation depletion-resistant lubricant-infused ice-repellent surfaces.

Cartilage-Inspired, High-Strength, and Heat-Tolerant Lubricating Hydrogels by Macrophase Separation.

Hydrogels are considered as a potential cartilage replacement material based on their structure being similar to natural cartilage, which are of great significance in repairing cartilage defects. However, it is difficult for the existing hydrogels to combine the high load bearing and low friction properties (37 °C) of cartilage through sample methods. Herein, we report a facile and new fabrication strategy to construct the PNIPAm/EYL hydrogel by using the macrophase separation of supersaturated N-isopropylacrylamide (NIPAm) monomer solution to promote the formation of liposomes from egg yolk lecithin (EYL) and asymmetric template method. The PNIPAm/EYL hydrogels possess a relatively high compressive strength (more than 12 MPa), fracture energy (9820 J/m2), good fatigue resistance, lubricating properties, and excellent biocompatibility. Compared with the PNIPAm hydrogel, the friction coefficient (COF 0.046) of PNIPAm/EYL hydrogel is reduced by 50%. More importantly, the COF (0.056) of PNIPAm/EYL hydrogel above lower critical solution temperature (LCST) does not increase significantly, exhibiting heat-tolerant lubricity. The finite element analysis further proves that PNIPAm/EYL hydrogel can effectively disperse the applied stress and dissipate energy under load conditions. This work not only provides new insights for the design of high-strength lubricating hydrogels but also lays a foundation for the treatment of cartilage injury as a substitute material.

Lubricating drops for contact lens discomfort in adults.

BACKGROUND: Contact lens discomfort is a symptom-based clinical diagnosis that affects 13% to 75% of contact lens wearers. The Tear Film and Ocular Surface Society defines contact lens discomfort as "a condition characterized by episodic or persistent adverse ocular sensations related to lens wear either with or without visual disturbance, resulting from reduced compatibility between the lens and ocular environment, which can lead to decreased wearing time and discontinuation from lens wear." Signs of the condition include conjunctival hyperemia, corneal and conjunctival staining, altered blinking patterns, lid wiper epitheliopathy, and meibomian gland dysfunction. Eye care specialists often treat contact lens discomfort with lubricating drops, including saline, although there is no clear evidence showing this treatment is effective and safe. OBJECTIVES: To evaluate the efficacy and safety of lubricating drops for ocular discomfort associated with contact lens wear in adults. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE, Embase.com, two other databases, and two trials registries to May 2024, without date or language restrictions. SELECTION CRITERIA: We included parallel-group randomized controlled trials (RCTs) that evaluated lubricating drops, including saline, versus no treatment, or that evaluated lubricating drops versus saline, in adult contact lens wearers. We included studies regardless of publication status, language, or year of publication. DATA COLLECTION AND ANALYSIS: We applied standard Cochrane methodology. The critical outcome was contact lens discomfort. Important outcomes were corneal fluorescein staining and conjunctival redness. Adverse outcomes were incident microbial keratitis, inflammatory corneal infiltrates, and participant discontinuation. We assessed risk of bias for outcomes reported in the summary of findings table using the Cochrane risk of bias tool RoB 2, and we rated the certainty of the evidence using GRADE. MAIN RESULTS: We included seven RCTs conducted in the USA, Canada, Italy, and France. They randomized a total of 463 participants to lubricating drops, saline, or no treatment. Four trials evaluated lubricating drops and saline versus no treatment, but one of them provided no usable outcome data. Three trials evaluated lubricating drops versus saline. Study characteristics All trial participants were adults, and the mean age ranged from 25.7 years to 36.7 years. The proportion of women varied from 15% to 82%. The trials lasted between one and four weeks. Of the five trials that reported contact lens discomfort, we judged three at high risk of bias, and considered the other two had some risk of bias concerns. Lubricating drops (including saline) versus no treatment Lubricating drops compared with no treatment may reduce contact lens discomfort, measured on a 37-point scale (lower is better), but the evidence is very uncertain (mean difference [MD] -5.9 points, 95% confidence interval [CI] -3.74 to -8.05; 2 RCTs; 119 participants). One trial found no difference between lubricating drops and no treatment in "end-of-day" comfort. The trial that compared saline with no treatment provided no results for the control group. Two studies measured corneal fluorescein staining on a scale of 0 to 20 (lower is better). We found low-certainty evidence of little to no difference between lubricating drops and no treatment in changes in the extent (MD -0.15 points, 95% CI -0.86 to 0.56; 2 RCTs; 119 participants), depth (MD -0.01 points, 95% CI -0.44 to 0.42; 2 RCTs; 119 participants), or type (MD 0.04 points, 95% CI -0.38 to 0.46; 2 RCTs; 119 participants) of corneal fluorescein staining scores. Regarding conjunctival redness, measured on a scale of 0 to 4 (lower is better), there was low-certainty evidence of little to no difference between lubricating drops and no treatment in nasal region scores (MD 0.10, 95% CI -0.29 to 0.49; 1 RCT; 73 participants) and temporal region scores (MD 0.00, 95% CI -0.39 to 0.39; 1 RCT; 73 participants). No studies reported microbial keratitis or inflammatory corneal infiltrates, and no trials reported vision-threatening adverse events up to four weeks of treatment. All trials reported the proportion of participants who discontinued participation. In two trials, no participants left any treatment group. Our meta-analysis of another two studies suggests little difference in the number of people who dropped out of the lubricating treatment group versus the no treatment group (risk ratio [RR] 1.42, 95% CI 0.19 to 10.94; 138 participants; low-certainty evidence). Lubricating drops versus saline Lubricating drops may have little to no effect compared with saline on contact lens discomfort measured on a visual analog scale of 0 to 100 (lower is better), but the evidence is very uncertain (MD 9.5 points, 95% CI -4.65 to 23.65; 1 RCT; 39 participants). No studies reported corneal fluorescein staining or conjunctival redness. No studies reported microbial keratitis or inflammatory corneal infiltrates, and no trials reported vision-threatening adverse events up to four weeks of treatment. Our meta-analysis of three studies suggests little difference in the number of people who dropped out of the lubricating treatment group versus the saline group (RR 1.56, 95% CI 0.47 to 5.12; 269 participants; low-certainty evidence). AUTHORS' CONCLUSIONS: Very low-certainty evidence suggests that lubricating drops may improve contact lens discomfort compared with no treatment, but may have little or no effect on contact lens discomfort compared with saline. Low-certainty evidence also suggests that lubricating drops may have no unwanted effects that would lead to discontinuation over one to four weeks. Current evidence suggests that prescribing lubricating drops (including saline) to people with contact lens discomfort is a viable option. However, most studies did not assess patient-reported contact lens (dis)comfort using a validated instrument. Therefore, further well-designed trials are needed to generate high-certainty evidence on patient-reported outcomes as well as on longer-term safety outcomes.

Mucoadhesive, antioxidant, and lubricant catechol-functionalized poly(phosphobetaine) as biomaterial nanotherapeutics for treating ocular dryness.

Dry eye disease (DED) is associated with ocular hyperosmolarity and inflammation. The marketed topical eye drops for DED treatment often lack bioavailability and precorneal residence time. In this study, we investigated catechol-functionalized polyzwitterion p(MPC-co-DMA), composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and dopamine methacrylamide (DMA) monomers, as potential topical nanotherapeutics for DED. The copolymers were synthesized via random free-radical copolymerization, producing different proportions of catecholic functionalization. All as-prepared polymer compositions displayed good ocular biocompatibility. At a feeding ratio of 1:1, p(MPC1-co-DMA1) can facilitate a robust mucoadhesion via Michael addition and/or Schiff base reaction, thus prolonging ocular residence time after 4 days of topical instillation. The hydration lubrication of MPC and radical-scavenging DMA endow the nano-agent to ease tear-film hyperosmolarity and corneal inflammation. A single dose of p(MPC1-co-DMA1) (1 mg/mL) after 4 days post-instillation can protect the cornea against reactive oxygen species, inhibiting cell apoptosis and the over-expression of pro-inflammatory factors (IL-6 and TNF-α). In clinical assessment, DED-induced rabbit eyes receiving p(MPC1-co-DMA1) could increase lacrimal fluid secretion by 5-fold higher than cyclosporine A. The catechol-functionalized polyzwitterion with enhanced lubricity, mucoadhesion, and anti-oxidation/anti-inflammation properties has shown high promise as a bioactive eye drop formulation for treating DED.

Prospective, multicenter, uncontrolled study on the effectiveness and safety of a hyaluronic acid water-based vaginal lubricant in alleviating vaginal dryness and dyspareunia.

BACKGROUND: Vaginal dryness (VD) represents a significant concern affecting women across diverse life stages, encompassing both pre- and postmenopausal women at any age. Dyspareunia, defined by genital pain that can be experienced before, during, or after intercourse, is often associated with vaginal dryness. AIM: This study aimed to evaluate the effectiveness and safety of a water-based vaginal lubricant with hyaluronic acid to reduce sexual discomfort associated with vaginal dryness. METHODS: A prospective, multicenter, uncontrolled clinical investigation was conducted over a three-month period in women aged 18 years or older experiencing pain or difficulty during sexual intercourse for whom the use of a vaginal lubricant was recommended. RESULTS: Significant improvements were observed in the FSFI scores, indicating enhanced sexual function (p < .001). Vaginal dryness symptoms, including irritation, dryness, itching, and dyspareunia, significantly decreased after product use (p < .001). CLINICAL IMPLICATIONS: This study contributes to the limited scientific knowledge on the application of lubricants in the context of symptoms associated with VD. STRENGTHS & LIMITATIONS: In addition to the short study period, inherent limitations of the study design, and lack of placebo control, it is pertinent to acknowledge that some of the pros used in this study were not based on validated questionnaires. However, as far as we know, this study is the only one that analyzes well-being and sexual pleasure as results using a lubricant formulated with hyaluronic acid. CONCLUSION: This tested vaginal lubricant with hyaluronic acid has demonstrated efficacy in improving vaginal dryness and female sexual function, particularly in reducing pain and improving lubrication during sexual intercourse, and showed a favorable safety profile, with minimal and transient adverse events.

Analysis of Tribology Properties of Trimethylolpropane-based Lubricant by Molecular Dynamics.

Currently, it is crucial for the lubricant formulation industry to explore cost-effective and environmentally friendly methodologies for analyzing the tribological properties of engine aviation lubricants under high-temperature and high-pressure operating conditions. This study demonstrates the feasibility of employing molecular dynamic simulations to gain essential insights into the evolution of the tribological properties of lubricants during operation. A three-layer molecular model was devised, comprising nickel aluminide molecules in the top and bottom layers, and polyol ester in the core. The impact of sliding velocities ranging from 20 km/h to 100 km/h was investigated under varying temperature and pressure conditions. Concentration, temperature and velocity profiles, radial distribution function, mean square displacement, and friction coefficient were calculated and analyzed in detail. Notably, the highest friction coefficients - ranging from 2.5 to 0.75 - were observed at the lowest temperature and pressure conditions tested. Conversely, other sections of the gas turbine exhibited substantially lower friction coefficients - ranging from 0 to 0.01.Simulations demonstrate that increasing pressure and temperature reduce polymer chain mobility, leading to stronger internal interactions within the lubricant. Consequently, lubricant adsorption onto metal surfaces decreases. Furthermore, the lubricant performs exceptionally well when its molecules encounter higher velocities and temperatures. Based on the results obtained, the research demonstrates that the presented technique provides both quantitative and qualitative tribological information essential for understanding a system molecular behavior, serving as a guiding framework for researchers in the field.

Comparison of Eco-Friendly Ionic Liquids and Commercial Bio-Derived Lubricant Additives in Terms of Tribological Performance and Aquatic Toxicity.

Approximately half of the lubricants sold globally find their way into the environment. The need for Environmentally Acceptable Lubricants (EALs) is gaining increased recognition. A lubricant is composed of a base oil and multiple functional additives. The literature has been focused on EAL base oils, with much less attention given to eco-friendly additives. This study presents the tribological performance and aquatic toxicity of four short-chain phosphonium-phosphate and ammonium-phosphate ionic liquids (ILs) as candidate anti-wear and friction-reducing additives for EALs. The results are benchmarked against those of four commercial bio-derived additives. The four ILs, at a mere 0.5 wt% concentration in a synthetic ester, demonstrated a 30-40% friction reduction and >99% wear reduction, superior to the commercial baselines. More impressively, all four ILs showed significantly lower toxicity than the bio-derived products. In an EPA-standard chronic aquatic toxicity test, the sensitive model organism, Ceriodaphnia dubia, had 90-100% survival when exposed to the ILs but 0% survival in exposure to the bio-derived products at the same concentration. This study offers scientific insights for the future development of eco-friendly ILs as lubricant additives.

Potential of Powder Rheology for Detecting Unforeseen Cross-Contamination of Foreign Active Pharmaceutical Ingredients.

Unexpected cross-contamination by foreign components during the manufacturing and quality control of pharmaceutical products poses a serious threat to the stable supply of drugs and the safety of customers. In Japan, in 2020, a mix-up containing a sleeping drug went undetected by liquid chromatography during the final quality test because the test focused only on the main active pharmaceutical ingredient (API) and known impurities. In this study, we assessed the ability of a powder rheometer to analyze powder characteristics in detail to determine whether it can detect the influence of foreign APIs on powder flow. Aspirin, which was used as the host API, was combined with the guest APIs (acetaminophen from two manufacturers and albumin tannate) and subsequently subjected to shear and stability tests. The influence of known lubricants (magnesium stearate and leucine) on powder flow was also evaluated for standardized comparison. Using microscopic morphological analysis, the surface of the powder was observed to confirm physical interactions between the host and guest APIs. In most cases, the guest APIs were statistically detected due to characteristics such as their powder diameter, pre-milling, and cohesion properties. Furthermore, we evaluated the flowability of a formulation incorporating guest APIs for direct compression method along with additives such as microcrystalline cellulose, potato starch, and lactose. Even in the presence of several additives, the influence of the added guest APIs was successfully detected. In conclusion, powder rheometry is a promising method for ensuring stable product quality and reducing the risk of unforeseen cross-contamination by foreign APIs.

Electrotunable friction with ionic liquid lubricants.

Room-temperature ionic liquids and their mixtures with organic solvents as lubricants open a route to control lubricity at the nanoscale via electrical polarization of the sliding surfaces. Electronanotribology is an emerging field that has a potential to realize in situ control of friction-that is, turning the friction on and off on demand. However, fulfilling its promise needs more research. Here we provide an overview of this emerging research area, from its birth to the current state, reviewing the main achievements in non-equilibrium molecular dynamics simulations and experiments using atomic force microscopes and surface force apparatus. We also present a discussion of the challenges that need to be solved for future applications of electrotunable friction.

Investigating the impact of condomless vaginal intercourse and lubricant use on the vaginal metabolome: a pre-post observational study.

OBJECTIVE: The vaginal metabolome is a significant factor in the vaginal microenvironment, and data are emerging on its independent role in urogenital health. Condomless vaginal intercourse and personal lubricant use are common practices that may affect the vaginal metabolome. The aim of the present study is to describe the associations between condomless intercourse and lubricant use on the vaginal metabolome. METHODS: This study used archived mid-vaginal swabs from a 10-week observational cohort of reproductive age women who self-collected samples and recorded behavioural diaries daily. Cases and controls were defined as participants who self-reported condomless vaginal intercourse with or without lubricant use, respectively. Samples were drawn prior to and following condomless vaginal intercourse. Twenty-two case participants were race/ethnicity matched to 22 control participants. Mid-vaginal swabs were subjected to 16S rRNA gene amplicon sequencing and untargeted ultrahigh performance liquid chromatography tandem mass spectroscopy metabolomics. Bayesian mixed-effects regression (unadjusted and adjusted for the vaginal microbiota) was used to evaluate differences in metabolite concentration associated with vaginal intercourse and lubricant use. RESULTS: Both condomless penile-vaginal intercourse and lubricant use were independently associated with higher (up to 8.3-fold) concentrations of metabolites indicative of epithelial damage (eg, sarcosine) and many host-produced antioxidants. Lubricant use was significantly associated with increases in lipids related to cellular damage, host-produced sphingolipids (antimicrobials), antioxidants and salicylate, a cooling agent common to lubricants, in a study design which controls for the independent effect of intercourse. Metabolites involved in oxidative stress and salicylate were strongly correlated with several molecular bacterial vaginosis-associated bacteria. CONCLUSIONS: This study provides important foundational data on how condomless vaginal-penile intercourse and lubricant use affect the vaginal metabolome and may affect the protective mechanisms in the vaginal microenvironment.

A randomized trial on the effectiveness and safety of 5 water-based personal lubricants.

BACKGROUND: A range of personal lubricants with different formulations and subsequent properties are available for relief of discomfort associated with vaginal dryness; however, there are limited clinical data to support the efficacy and safety of many commercially available lubricants. AIM: To determine the effectiveness and safety of 5 water-based personal lubricants for the relief of intimate discomfort associated with vaginal dryness in pre- and postmenopausal women: 4 that were formulated to meet the World Health Organization (WHO) guidelines for osmolality and pH and 1 preexisting lubricant of higher osmolality and pH. METHODS: An open-label, parallel-design study was performed in women aged 18 to 65 years with mild-to-moderate vaginal dryness and dyspareunia. Participants were randomized to 1 of 5 lubricants (A-E) from 3 brands (Durex, KY, Queen V). They were instructed to use their allocated lubricants during vaginal intercourse at least once a week over a 4-week period. The Female Sexual Function Index (FSFI) measured sexual functioning after 4 weeks of use as an indicator of lubricant performance. OUTCOMES: The primary outcome was change from baseline in total FSFI score after 4 weeks of product use. RESULTS: A total of 174 women completed the study. The primary end point-a prespecified increase in FSFI ≥4 points from baseline after 4 weeks of use-was met by all 5 lubricants tested. A statistically significant improvement was observed across all 6 domains of the FSFI from baseline to 4 weeks of use with all 5 lubricants (P < .0001 for lubrication and pain reduction and P < .05 for all other domains). No serious adverse events occurred in the study, and the tolerance of all 5 lubricants was good/very good. CLINICAL IMPLICATIONS: The efficacy and safety of the tested lubricants are not compromised when formulated to meet the WHO criterion of osmolality ≤1200 mOsm/kg. The lubricants tested in this investigation can be used not only to relieve symptomatology of vaginal dryness and dyspareunia but also to enhance overall sexual satisfaction. STRENGTHS AND LIMITATIONS: This study provides clinical evidence for the efficacy and safety of 5 lubricants, including those formulated to meet WHO guidelines, in relieving symptoms of vaginal dryness and improving the overall sexual experience. The open-label design may have introduced bias into the study. CONCLUSION: All 5 lubricants, including those formulated to be compliant with guidelines on pH and osmolality, can be considered effective and well tolerated for the relief of discomfort associated with vaginal dryness.

Investigation of Dispersion Kinetics of Particulate Lubricants and their Effect on the Mechanical Strength of MCC Tablets.

INTRODUCTION: Tablets are commonly produced by internally adding particulate lubricants, which are known to possibly lower the mechanical strength of tablets. This reduction is caused by the coverage of matrix forming components by lubricant particles, resulting in decreased interparticulate interactions. The known incompatibilities with some active compounds of the predominantly used lubricant, magnesium stearate, call for the in-depth characterization of alternative lubricants. PURPOSE: Investigation of the dispersion behavior of five commonly applied pharmaceutical lubricants by mathematically modeling the dispersion kinetics for short and extended mixing times. METHODS: The dispersion behavior of five different pharmaceutical lubricants were examined by systematically varying lubricant concentration and mixing time of binary formulations and evaluating the kinetic of tensile strength reduction by theoretically estimating the surface coverage based on particle sizes. RESULTS: For short mixing times, a unifying relationship between compactibility reduction and theoretical surface coverage was identified. Subsequently, for extended mixing times, distinct differences in the shear strength and dispersion kinetics of the investigated lubricants were found. CONCLUSIONS: The lubricant particle size controls the tensile strength reduction if short mixing times are applied. For extended mixing times, the investigated lubricants can be divided into two groups in terms of dispersion kinetics. Possible underlying reasons are discussed in detail in order to enhance the general understanding of lubricant dispersions in tablet formulations.

Effects of 2,6-di-tert-butyl-hydroxytotulene and mineral-lubricant base oils on microbial communities during lubricants biodegradation.

2,6-Di-tert-butyl-hydroxytotulene (BHT) is an additive commonly used in the manufacturing of lubricants to improve their antioxidant properties. However, in this study, we found that BHT affects the biodegradation of bio-lubricants by influencing the microbial community during the degradation of bio-lubricants. Specifically, BHT was found to reduce bacterial richness in activated sludge, but it increased the relative abundance of Actinobacteria (from 21.24% to 40.89%), Rhodococcus (from 17.15% to 31.25%), Dietzia (from 0.069% to 6.49%), and Aequorivita (from 0.90% to 1.85%). LEfSe analysis and co-occurrence network analysis suggested that Actinobacteria could be potential biomarkers and keystone taxa in microbial communities. Using the MetaCyc pathway database, the study found that BHT interfered with cellular biosynthetic processes. Additionally, the study also showed that mineral-lubricant base oils, which are difficult to degrade, significantly altered the diversity and composition of the microbiome. Overall, the findings demonstrate that BHT and mineral-lubricant base oils can substantially alter bacterial richness, structure, and function, potentially contributing to the difficulty in degrading lubricants. These findings have implications for the development of more biodegradable lubricants and the management of industrial waste containing lubricants.

Sequential treatment in vulvovaginal atrophy.

Vulvovaginal atrophy (VVA) is a chronic and progressive disease that affects sexuality and quality of life. VVA is preventable and treatable, but requires long-term and often sequential treatment. Sequential treatment consists of designing a strategy that uses one or more medications for a long enough time to achieve the desired benefits with minimal risk and maximum adherence. Currently available therapeutic options consist of topical over-the-counter products (including non-hormonal lubricants and moisturizers applied to the vagina), systemic hormone therapy and estrogens, and prescribed vaginal dehydroepiandrosterone (DHEA). In addition, we have a selective estrogen receptor modulator, ospemifene, and new energy-based treatments (laser and radiofrequency). There are clear differences between the treatments both in the mechanism of action and in the efficacy. Compliance is very low, and patients complain about the use of the vaginal route, often due to its low efficacy, or express fear of the long-term use of estrogens or the price of the treatments. We believe that, as a first option, and for physiological, preventive and efficacy reasons, we should consider the prescription of treatments that work on estrogen receptors. As a second option, there are vaginal moisturizers, which are effective on symptoms but do not prevent or improve conditions. Finally, techniques using heat, which although each time represent a clearer alternative, but on the other hand are the cost and the long-term safety data, give us a third option. Of course, we consider that vulvar moisturizers and lubricants can be used at any time.

Effects of Granulated Lactose Characteristics and Lubricant Blending Conditions on Tablet Physical Properties in Direct Powder Compression.

Lactose is an excipient used extensively for bulking, diluting, and molding active pharmaceutical ingredients in tablet manufacturing. Particularly, granulated lactose (GL) intended for direct powder compression has distinct properties due to differences in manufacturing methods. It contributes to handling blended powders for tableting and tablet quality. In this study, we aimed to compare the functions of different forms of GL added as excipients during direct powder compression on the tablet properties and the effect of magnesium stearate (Mg-S) used as a lubricant on each type of GL. Different GL types obtained using different manufacturing methods (agitated granulation, GL-AG; spray-dried granulation, GL-SD; fluidized bed granulation, GL-FB) were blended with maize starch, low-substituted hydroxypropyl cellulose, and paracetamol in a V-type blender for 10 min. Mg-S was added at varying amounts (0.1, 1.0, and 2.0%) and blending times (5, 10, and 30 min) for the nine types of blended powders for tableting formulation. The powders were tableted, and the tablets were evaluated for weight and drug loading variations, tensile strength, friability, and disintegration time. When tablets with the same blending conditions were compared, the tensile strength and disintegration time were in the order of GL-FB > GL-SD > GL-AG. For each GL, we analyzed the effects of changes in the added amount of Mg-S and blending time using contour plots, evaluated the effects of blending conditions on tablet properties, and determined the target tablet properties. We investigated the optimization of the lubricant blending conditions to obtain suitable tablets.

Flammability of Ocular Surface Lubricants.

PURPOSE: Surgical fires pose a substantial risk to patients and can cause significant injury, especially in oculofacial surgery. Ocular surface lubricants can potentially act as fuel for an operating room fire. We present an experimental analysis of the flammability of 9 commonly used ophthalmic lubricants under 4 ignition sources used in oculofacial surgery with and without supplemental oxygen. METHODS: The flammability of 9 ophthalmic lubricants were tested under various operating room conditions. Each lubricant was exposed to 4 different ignition sources: an open flame lighter, monopolar cautery, bipolar cautery, and hand-held high temperature cautery, and the response of the lubricant was recorded. The testing was conducted both in room air and with 6 L/minute of 100% oxygen directed at the lubricant through a nasal cannula. Any reaction in which there was ignition, sparking, smoking, or a transient or permanent change in appearance of the lubricant was deemed notable. RESULTS: Of the 9 lubricants tested, 4 displayed a reaction to the ignition source. Without supplemental oxygen, 100% petrolatum and neomycin-polysporin-bacitracin-hydrocortisone ointment produced some smoke when applied with the high temperature cautery. Notably, under both the conditions of no supplemental oxygen and with the addition of 6 L/minute of 100% oxygen, the carboxymethylcellulose drops and lidocaine jelly both conducted and sparked with the monopolar cautery leaving visible burn marks on the paper. CONCLUSIONS: The overall fire hazard posed by ocular surface lubricants is low. Some topical lubricants can conduct electricity from monopolar cautery, which could increase the risk of inadvertent electrical burns. Certain lubricants could potentially become a fuel source when used in combination with hand-held high temperature battery cautery. Bipolar cautery was not associated with either increased conductivity or flammability with any of the lubricants tested.

Precorneal retention time of ocular lubricants measured with fluorophotometry in healthy dogs.

OBJECTIVE: Determine the precorneal retention time of five different ocular lubricants commonly used in dogs. ANIMALS STUDIED: Six healthy Beagle dogs (n = 12 eyes). PROCEDURES: Five ocular lubricants were studied: Artificial Tears Solution® (1.4% polyvinyl alcohol), I-Drop® Vet Plus (0.25% hyaluronate), Optixcare® Eye Lube Plus (0.25% hyaluronate), Systane® Ultra (0.4% polyethylene glycol 400 and 0.3% propylene glycol), and Artificial Tears Ointment® (mineral oil/white petrolatum). Each lubricant was mixed with 10% sodium fluorescein to achieve 1% fluorescein formulations. Following topical administration of 35 mg in each eye, tear fluid was collected with capillary tubes at selected times (0, 1, 5, 10, 20, 30, 40, 50, 60, 90, 120, 180 min) and fluorescein concentrations were measured with a computerized scanning ocular fluorophotometer. RESULTS: Tear fluorescence was significantly greater with Artificial Tears Ointment® compared with other lubricant formulations from 1 to 20 min post-administration. Median (range) precorneal retention times were significantly different among the 5 lubricants, ranging from 40 minutes (20-90 min) for Artificial Tears Ointment®, 35 min (20-90 min) for Systane® Ultra, 30 min (10-60 min) for I-Drop® Vet Plus, 25 min (10-60 min) for Optixcare® Eye Lube Plus, and 10 min (10-20 min) for Artificial Tears Solution®. Precorneal retention time was significantly lower for Artificial Tears Solution® compared with the other 4 formulations. CONCLUSIONS: This study established normative data for the retention time of common lubricants on the ocular surface of dogs, which may be used to guide clinicians with their choice of lubricant and frequency of administration.

At Least 10-fold Higher Lubricity of Molecularly Thin D2O vs H2O Films at Single-Layer Graphene-Mica Interfaces.

Interfacial water is a widespread lubricant down to the nanometer scale. We investigate the lubricities of molecularly thin H2O and D2O films confined between mica and graphene, via the relaxation of initially applied strain in graphene employing Raman spectroscopy. Surprisingly, the D2O films are at least 1 order of magnitude more lubricant than H2O films, despite the similar bulk viscosities of the two liquids. We propose a mechanism based on the known selective permeation of protons vs deuterons through graphene. Permeated protons and left behind hydroxides may form ion pairs clamping across the graphene sheet and thereby hindering the graphene from sliding on the water layer. This explains the lower lubricity but also the hindering diffusivity of the water layer, which yields a high effective viscosity in accordance with findings in dewetting experiments. Our work elucidates an unexpected effect and provides clues to the behavior of graphene on hydrous surfaces.

Amide/Amino-Based Functional Additives for Lubricants: Structure, Antimicrobial Activity and Wear Resistance.

The lubricating properties of the lubricants were tested under boundary friction conditions; it was found that the surface-active additives had reduced the wear mark and thus the value of the Goz/40 parameter (limiting load of wear). The introduction of a surfactant containing amide compounds into the oils and greases was highly effective in slowing down the oxidation process. Lubricants containing mono-15 ([3-(N,N,N-dimethylbuthylamine)propyl]hexadecanamide chloride) and 15-4-15 (tetramethylene-bis [3-(N,N,N-dimethylamine)propyl]hexadecanamide) additives were characterised by higher oxidation stability compared to the unmodified lubricants. Both of the analysed substances showed bactericidal properties against Staphylococcus aureus and Salmonella enteritica. Tests of antibacterial activity in the lubricants with the addition of mono-15 and 15-4-15 confirmed that these lubricants can be considered bactericidal against Gram-positive and Gram-negative bacteria.

Effects of tableting process parameters and powder lubrication levels on tablet surface temperature and moisture content.

Punch sticking is a recurrent problem during the pharmaceutical tableting process. Powder moisture content plays a key role in the buildup of sticking; it evaporates due to increased tablet temperature, accumulates at the punch-tablet interface, and causes sticking through capillary force. This study investigated the effects of compaction pressure (CP), compaction speed (CS), and lubrication level (magnesium stearate (MgSt) ratio) on tablet surface temperature (TST) and tablet surface moisture content (TSMC). TST and TSMC were measured with an infrared thermal camera and near-infrared sensor, respectively. Microcrystalline cellulose was used as the tableting powder and MgSt as the lubricant. The low range of CS values (16-32 mm/s) considered in this study did not have significant effects on TST and TSMC. MgSt ratio had a significant positive effect on TST; this may be explained by the increase in powder blend effusivity with the addition of MgSt. However, MgSt ratio did not have a significant effect on TSMC. CP had a significant positive effect on both TST and TSMC. Increased CP induced higher heat generation through particle deformation and friction during the compaction phase, leading to increased TST. Furthermore, the water vapor diffusion rate through the powder bed might have increased due to the rise in thermal energy and led to further moisture accumulation at the tablet-punch interface, causing the significant positive effect of CP on TSMC. This result may explain the occurrence of sticking regardless of the CP applied during the tableting process.