Biodiesel production and exploring properties of Datura stramonium L. oil with its optimization using combined approaches-Taguchi, grey relational analysis, and response surface methodology

Biodiesel production through the synthesis of Datura stramonium L. oil is studied to explore the most efficient approaches to suggest an alternate feedstock for biodiesel production. The main objective of this work is to optimize the process variables of biodiesel synthesis by using some statistical approach (Taguchi method, grey relational analysis (GRA), and response surface methodology (RSM) analyzing three parameters, i.e., alcohol-to-oil molar ratio, catalyst (NaOH) concentration, and process temperature for achieving maximum biodiesel derived from Datura stramonium L. oil. The transesterification process is applied by using an ultrasonic-assisted technique. Grey relational analysis (GRA) was successfully applied with the Taguchi method resulting in the optimum combination of A2B1C1. Based on the findings, the best operating conditions for transesterifying are attained with the RSM approach consisting of a 5.697:1 molar ratio (level 2), 0.3 (wt.%) NaOH concentration (level 1), and 70 °C process temperature (level 1). With a value of 87.02%, these ideal operating conditions produce the maximum yield as compared to grey relational analysis (GRA) yields 83.99%. The obtained results have been verified through the characterization of oil and biodiesel as well. Also, the fuel qualities of DSL biodiesel were identified and assessed. DSL oil was found 137.6 degrees of unsaturation during fatty acid profile analysis. DSL biodiesel was found the best kinematic viscosity (4.2 mm2/s) and acid value (0.49) when compared to Karanja and palm biodiesel. D. stramonium L. was recognized as a suitable species for biodiesel feedstock according to the findings.

High-density zwitterionic polymer brushes exhibit robust lubrication properties and high antithrombotic efficacy in blood-contacting medical devices

High-performance catheters are essential for interventional surgeries, requiring reliable anti-adhesive and lubricated surfaces. This article develops a strategy for constructing high-density sulfobetaine zwitterionic polymer brushes on the surface of catheters, utilizing dopamine and sodium alginate as the primary intermediate layers, where dopamine provides mussel-protein-like adhesion to anchor the polymer brushes to the catheter surface. Hydroxyl-rich sodium alginate increases the number of grafting sites and improves the grafting mass by more than 4 times. The developed high-density zwitterionic polymer brushes achieve long-lasting and effective lubricity (μ<0.0078) and are implanted in rabbits for four hours without bio-adhesion and thrombosis in the absence of anticoagulants such as heparin. Experiments and molecular dynamics simulations demonstrate that graft mass plays a decisive role in the lubricity and anti-adhesion of polymer brushes, and it is proposed to predict the anti-adhesion of polymer brushes by their lubricity to avoid costly and time-consuming bioassays during the development of amphoteric polymer brushes. A quantitative influence of hydration in the anti-adhesion properties of amphiphilic polymer brushes is also revealed. Thus, this study provides a new approach to safe, long-lasting lubrication and anticoagulant surface modification for medical devices in contact with blood. STATEMENT OF SIGNIFICANCE: High friction and bioadhesion on medical device surfaces can pose a significant risk to patients. In response, we have developed a safer, simpler, and more application-specific surface modification strategy that addresses both the lubrication and anti-bioadhesion needs of medical device surfaces. We used dopamine and sodium alginate as intermediate layers to drastically increase the grafting density of the zwitterionic brushes and enabled the modified surfaces to have an extremely low coefficient of friction (μ = 0.0078) and to remain non-bioadhesive for 4 hours in vivo. Furthermore, we used molecular dynamics simulations to gain insight into the mechanisms behind the superior anti-adhesion properties of the high-density polymer brushes. Our work contributes to the development and application of surface-modified coatings.

A narrative review investigating the potential effect of lubrication as a mitigation strategy for whey protein-associated mouthdrying

Whey is consumed by active adults to aid muscle recovery and growth, the general population as a nutritious convenient food, and by older adults to prevent sarcopenia due to its high leucine content. However, whey protein has poor consumer acceptance in this latter demographic, partially due to mouthdrying. This is thought to result from electrostatic interactions between whey and salivary proteins, mucoadhesion to the oral mucosa, and the inherent astringency of acidity. Previous unsuccessful mitigation strategies include viscosity, sweetness and fat manipulation. This literature review reveals support for increasing lubrication to reduce mouthdrying. However, of the 50 papers reviewed, none have proposed a method by which whey protein could be modified as an ingredient to reduce mouthdrying in whey-fortified products. This review recommends the use of modern technologies to increase lubrication as a novel mitigation strategy to reduce mouthdrying, with the potential to increase consumer acceptance.

Diblock bottlebrush polymer in a non-polar medium: Self-assembly, surface forces, and superlubricity

Whilst bottlebrush polymers have been studied in aqueous media for their conjectured role in biolubrication, surface forces and friction mediated by bottlebrush polymers in non-polar media have not been previously reported. Here, small-angle neutron scattering (SANS) showed that a diblock bottlebrush copolymer (oligoethyleneglycol acrylate/ethylhexyl acrylate; OEGA/EHA) formed spherical core-shell aggregates in n-dodecane (a model oil) in the polymer concentration range 0.1-2.0 wt%, with a radius of gyration Rg ∼ 7 nm, comprising 40-65 polymer molecules per aggregate. The surface force apparatus (SFA) measurements revealed purely repulsive forces between surfaces bearing inhomogeneous polymer layers of thickness L ∼ 13-23 nm, attributed to adsorption of a mixture of polymer chains and surface-deformed micelles. Despite the surface inhomogeneity, the polymer layers could mediate effective lubrication, demonstrating superlubricity with the friction coefficient as low as µ ∼ 0.003. The analysis of velocity-dependence of friction using the Eyring model shed light on the mechanism of the frictional process. That is, the friction mediation was consistent with the presence of nanoscopic surface aggregates, with possible contributions from a gel-like network formed by the polymer chains on the surface. These unprecedented results, correlating self-assembled polymer micelle structure with the surface forces and friction the polymer layers mediate, highlight the potential of polymers with the diblock bottlebrush architecture widespread in biological living systems, in tailoring desired surface interactions in non-polar media.

The role of membrane components on the oleosome lubrication properties

HYPOTHESIS

Oleosomes are natural oil droplets with a unique phospholipid/protein membrane, abundant in plant seeds, from which they can be extracted and used in emulsion-based materials, such as foods, cosmetics and pharmaceutics. The lubrication properties of such materials are essential, on one hand, due to the importance of the in-mouth creaminess for the consumed products or the importance of spreading the topical creams. Therefore, here, we will evaluate the lubrication properties of oleosomes, and how these properties are affected by the components at the oleosome membrane.

EXPERIMENT

Oleosomes were extracted, and their oral lubricating properties were evaluated using tribology. To understand the influence of the oil droplet membrane composition, reconstituted oleosomes were also studied, with membranes that differed in protein/lecithin ratio. Additionally, whey protein- and lecithin-stabilised emulsions were used as reference samples. Confocal laser scattering microscopy was used to study the samples visually before and after tribological analysis.

FINDINGS

Oleosomes followed a ball-bearing mechanism, which was probably related to their high physical stability due to the presence of membrane proteins. When the membrane protein concentration at the surface was reduced, the droplet stability weakened, leading to plating-out lubrication. Following our results, we elucidated the oleosome lubrication mechanism and showed their possible control by changing the membrane composition.

Effect of particle size on the dispersion behavior of magnesium stearate blended with microcrystalline cellulose

The majority of tablets manufactured contain lubricants to reduce friction during ejection. However, especially for plastically deforming materials, e.g., microcrystalline cellulose (MCC), the internal addition of lubricants is known to reduce tablet tensile strength. This reduction is caused by the surface coverage by lubricant particles, the extent of which depends on both process and formulation parameters. Previously published models to predict the lubrication effect on mechanical strength do not account for changes in the excipient particle size. In this study, the impact of both lubricant concentration and mixing time on the tensile strength of tablets consisting of three different grades of MCC and four grades of magnesium stearate (MgSt) was evaluated. By taking into account the particle size of the applied excipients, a unifying relationship between the theoretically estimated surface coverage and compactibility reduction was identified. Evaluating the dispersion kinetics of MgSt as a function of time reveals a substantial impact of the initial surface coverage on the dispersion rate, while the minimal tensile strength was found to be comparable for the majority of formulations. In summary, the presented work extends the knowledge of lubricant dispersion and facilitates the reduction of necessary experiments during the development of new tablet formulations.

Design, preparation, and characterization of lubricating polymer brushes for biomedical applications

The lubrication modification of biomedical devices significantly enhances the functionality of implanted interventional medical devices, thereby providing additional benefits for patients. Polymer brush coating provides a convenient and efficient method for surface modification while ensuring the preservation of the substrate's original properties. The current research has focused on a "trial and error" method to finding polymer brushes with superior lubricity qualities, which is time-consuming and expensive, as obtaining effective and long-lasting lubricity properties for polymer brushes is difficult. This review summarizes recent research advances in the biomedical field in the design, material selection, preparation, and characterization of lubricating and antifouling polymer brushes, which follow the polymer brush development process. This review begins by examining various approaches to polymer brush design, including molecular dynamics simulation and machine learning, from the fundamentals of polymer brush lubrication. Recent advancements in polymer brush design are then synthesized and potential avenues for future research are explored. Emphasis is placed on the burgeoning field of zwitterionic polymer brushes, and highlighting the broad prospects of supramolecular polymer brushes based on host-guest interactions in the field of self-repairing polymer brush applications. The review culminates by providing a summary of methodologies for characterizing the structural and functional attributes of polymer brushes. It is believed that a development approach for polymer brushes based on "design-material selection-preparation-characterization" can be created, easing the challenge of creating polymer brushes with high-performance lubricating qualities and enabling the on-demand creation of coatings. STATEMENT OF SIGNIFICANCE: Biomedical devices have severe lubrication modification needs, and surface lubrication modification by polymer brush coating is currently the most promising means. However, the design and preparation of polymer brushes often involves "iterative testing" to find polymer brushes with excellent lubrication properties, which is both time-consuming and expensive. This review proposes a polymer brush development process based on the "design-material selection-preparation-characterization" strategy and summarizes recent research advances and trends in the design, material selection, preparation, and characterization of polymer brushes. This review will help polymer brush researchers by alleviating the challenges of creating polymer brushes with high-performance lubricity and promises to enable the on-demand construction of polymer brush lubrication coatings.

Successful Formulation Window for the design of pharmaceutical tablets with required mechanical properties

Pharmaceutical tablet formulations combine the active ingredient with processing aids and functional components. This paper evaluates compressibility based predictive models for binary and ternary formulations to establish an acceptable range of tablet compression parameters that satisfy prescribed quality target criteria for tablets including minimum tablet strength and processing constraints such as maximum ejection stress and maximum compaction pressure. The concept of Successful Formulation Window (SFW) is introduced. A methodology is proposed to determine the SFW for a given formulation based on compaction simulator data collected for individual formulation components. The methodology is validated for binary and ternary mixtures and lubricated formulations. The SFW analysis was developed to support tablet formulation design to meet mechanical requirements.

Versatile MXene Gels Assisted by Brief and Low-Strength Centrifugation

Due to the mutual repulsion between their hydrophilic surface terminations and the high surface energy facilitating their random restacking, 2D MXene nanosheets usually cannot self-assemble into 3D macroscopic gels with various applications in the absence of proper linking agents. In this work, a rapid spontaneous gelation of Ti3C2Tx MXene with a very low dispersion concentration of 0.5 mg mL-1 into multifunctional architectures under moderate centrifugation is illustrated. The as-prepared MXene gels exhibit reconfigurable internal structures and tunable rheological, tribological, electrochemical, infrared-emissive and photothermal-conversion properties based on the pH-induced changes in the surface chemistry of Ti3C2Tx nanosheets. By adopting a gel with optimized pH value, high lubrication, exceptional specific capacitances (~ 635 and ~ 408 F g-1 at 5 and 100 mV s-1, respectively), long-term capacitance retention (~ 96.7% after 10,000 cycles) and high-precision screen- or extrusion-printing into different high-resolution anticounterfeiting patterns can be achieved, thus displaying extensive potential applications in the fields of semi-solid lubrication, controllable devices, supercapacitors, information encryption and infrared camouflaging.

Modulating mechanobiology as a therapeutic target for synovial fibrosis to restore joint lubrication

OBJECTIVES

Fibroses are disorders linked to persistence of myofibroblasts due to biochemical (e.g., Transforming growth factor-β) and biophysical cues (e.g., a stiff microenvironment). In the context of osteoarthritis, fibrotic changes in the joint-lining synovium have been linked with disease progression. The objective of this study was to probe synovial fibroblast mechanobiology and how essential functions (i.e., lubrication) are altered in fibrotic environments.

DESIGN

Both ex vivo and in vitro synovium models were assessed for fibrotic and lubrication biomarkers to better understand the role of mechanobiology and lubrication. Additionally, in vitro, work on small molecules targeting mechanobiology was assessed.

RESULTS

Our results indicated that modulating mechanobiology could rescue the fibrotic phenotype instigated by stiffening microenvironment that resulted in altered lubricant expression. A small molecule therapeutic, fasudil, blocked ROCK-mediated contractility and this inhibition of the fibrotic mechano-response of synovial fibroblasts restored proper lubrication function, providing insight into mechanisms of disease progression as well as a new avenue for therapeutic development.

CONCLUSION

This study identifies synovial fibrosis as a condition that potentially has joint-wide deficits through inhibiting lubrication. Additionally, modulating mechanobiology (i.e., ROCK-mediated contractility) may pose a potential target for small molecule therapies that can be delivered to the joint space.

CLASSIFICATION

Applied Biological Sciences.

The effect of cations and epigallocatechin gallate on in vitro salivary lubrication

Ionic valency influences oral processing by changing salivary behavior and merits more attention since little is known. In this study, the influence of three ionic valences (monovalent, divalent and trivalent), ionic strength and epigallocatechin gallate (EGCG) on lubricating properties of saliva were investigated. Tribological measurements were used to characterize the lubrication response of KCl, MgCl2, FeCl3, and AlCl3 in combination with EGCG to the ex vivo salivary pellicle. KCl at 150 mM ionic strength provided extra lubrication via hydration lubrication. Contrarily, trivalent salts aggregated together with the salivary mucins via ionic cross-link interactions, which led to a decrease in salivary lubrication. FeCl3 and AlCl3 affected the salivary lubrication differently, which was attributed to changes in the pH. Finally, in presence of EGCG, FeCl3 interacted with EGCG via chelating interactions, preventing salivary protein aggregation. This resulted in less desorption of the salivary film, retaining the lubrication ability of salivary proteins.

Functional nano drug delivery system with dual lubrication and immune escape for treating osteoarthritis

Local drug delivery via inter-articular injection offers a promising scenario to treat the most common joint disease, osteoarthritis (OA), which is closely associated with the increased friction or cartilage degeneration and the inflammatory syndrome of synovium. Therefore, it is quite necessary to improve the retention of drug delivery system within synovial joint, simultaneously restore the lubrication of degraded cartilage and meanwhile alleviate the inflammation. In this study, we propose a hydrophilic coating modified nano-liposome drug carrier (PMPC-Lipo) to achieve these functions. A modified chain transfer agent was utilized to polymerize 2-methacryloyloxyethyl phosphorylcholine (MPC), the obtained polymer, combined with lecithin and cholesterol, formed a liposome (PMPC-Lipo) where poly (MPC) acted as hydrophilic coating. PMPC-Lipo was found to restore the lubrication of mechanically damage cartilage (mimicking OA conditions) to the level like healthy cartilage due to the hydration lubrication. Additionally, due to the presence of poly (MPC), we also found PMPC-Lipo avoid the recognition of macrophage and thus escape from the phagocytosis to prolong its retention in synovial joint. Furthermore, after encapsulating gallic acid (GA) into PMPC-Lipo, the obtained GA-PMPC-Lipo can effectively scavenge reactive oxygen species and restore the imbalance of matrix secretion in inflammatory chondrocytes. Collectively, the proposed GA-PMPC-Lipo may provide a new idea for osteoarthritis treatment by providing both long-term effective drug action and excellent lubrication properties.

Improved sexuality and satisfactory lubrication after genital affirmation surgery using penile skin inversion in transgender women: A satisfaction study

INTRODUCTION

Genital affirmation surgery (GAS) requests are consistently increasing in demand. The gold standard is penile skin inversion, using cutaneous grafting for neovagina creation. The aim is to achieve the most realistic results both physically and functionally. Different studies have contradictory results, and the use of lubrication is insufficiently clear, while the use of sigmoidoplasty has been defended for constant lubrication.

AIMS

Our aim was to evaluate transgender women's sexual function and lubrication after vaginoplasty by penile skin inversion.

METHODS

We performed a prospective study on 45 patients who underwent primary penile inversion vaginoplasty. Participants answered two questionnaires during the follow-up consultation: the Female Sexual Function Index (FSFI) and an 18-item custom questionnaire.

RESULTS

The average FSFI score of our patients was 28.9, up to the cut-off defining a sexual disorder. Compared to the Wylomanski control group, no differences were found for the FSFI score and in the subgroups. Considering lubrication, 69% of the patients were satisfied or very satisfied with their lubrication. Furthermore, 53% reported a fluid release at each orgasm.

CONCLUSION

This study reported high satisfaction for both sexuality and lubrication, proning against penile inversion's GAS bad reputation concerning postoperative lubrication. A squirting effect was described for the first time and was present in 53% of our transpatients.

Sodium lauryl sulfate as lubricant in tablets formulations: Is it worth?

Lubricants are excipients used in tablet formulations to reduce friction and adhesion forces within the die or on the punches surface during the manufacturing process. Despite these excipients are always required for the tablets production, their amount must be carefully evaluated since lubricants can negatively impact on mechanical strength, disintegration and dissolution behavior of solid dosage forms. Alternative compounds have been suggested to overcome the issues of conventional lubricants and sodium lauryl sulfate (SDS) is one of the most promising one. Despite SDS has been object of several investigations, a definitive conclusion on its effectiveness cannot still be drawn. Particularly, its efficacy on tablets disaggregation and API dissolution is still unclear. Here, the effect of SDS on all the relevant features of tablets and tableting process has been evaluated on immediate release hydrophobic tablets formulations in comparison with conventional lubricants. The results of this investigation are quite outspoken: SDS has a low lubricant power while it determines only a limited improvement on tablets hardness. It greatly improves the tablets wettability but only on model formulations, the presence of superdisintegrants resets its effectiveness and any possible effect on tablets disaggregation. None of the tested formulations showed improvement on the API dissolution rate.

A lubricant and adhesive hydrogel cross-linked from hyaluronic acid and chitosan for articular cartilage regeneration

Trauma-induced articular cartilage damages are common in clinical practice. Hydrogels have been used to fill the cartilage defects and act as extracellular matrices for cell migration and tissue regeneration. Lubrication and stability of the filler materials are essential to achieve a satisfying healing effect in cartilage regeneration. However, conventional hydrogels failed to provide a lubricous effect, or could not anchor to the wound to maintain a stable curing effect. Herein, we fabricated dually cross-linked hydrogels using oxidized hyaluronic acid (OHA) and N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC) methacrylate (HTCCMA). The OHA/HTCCMA hydrogels, which were dynamically cross-linked and then covalently cross-linked by photo-irradiation, showed appropriate rheological properties and self-healing capability. The hydrogels exhibited moderate and stable tissue adhesion property due to formation of dynamic covalent bonds with the cartilage surface. The coefficient of friction values were 0.065 and 0.078 for the dynamically cross-linked and double-cross-linked hydrogels, respectively, demonstrating superior lubrication. In vitro studies showed that the hydrogels had good antibacterial ability and promoted cell proliferation. In vivo studies confirmed that the hydrogels were biocompatible and biodegradable, and exhibited a robust regenerating ability for articular cartilage. This lubricant-adhesive hydrogel is expected to be promising for the treatment of joint injuries as well as regeneration.

Anti-corrosive non-aqueous DBSA/MEA lamellar liquid crystal lubrication system

HYPOTHESIS

Since lamellar liquid crystals (LLCS) could be used for lubrication, many LLCS systems have been constructed to improve lubrication performance. However, most studies focused on the LLCS of the water system, and its corrosiveness brought some limitations to its application. Therefore, it is necessary to construct a non-aqueous LLCS system with good lubrication and anti-corrosion properties to improve its applicability.

EXPERIMENTS

Anionic surfactant dodecyl benzene sulfonic acid (DBSA) was used to construct non-aqueous LLCS in different solvents, including monoethanolamine (MEA) and diethanolamine (DEA). DBSA/H₂O LLCS system was constructed for comparison. The LLCS was characterized by polarizing microscope (POM), small-angle X-ray scattering (SAXS), and rheology. Its microstructure was discussed. Meanwhile, we evaluated the lubrication and anti-corrosion performance of LLCS. Its lubrication mechanism was explained through tribology tests and X-ray photoelectron spectrometer (XPS) analysis of the wear scar surface. Its anti-corrosion mechanism was investigated by using the weightlessness method, electrochemical test method, and quantum chemical theoretical calculations.

FINDINGS

The DBSA/MEA non-aqueous LLCS system showed better lubrication performance than DBSA/DEA and DBSA/H₂O LLCS. It can adsorb on the surface of the friction pair to form a lubrication friction film, which plays a better role in reducing friction and wear. The DBSA/MEA LLCS is less corrosive to metals because it can effectively isolate oxygen and water in the air between friction pairs. Furthermore, the lone pair electrons in the 2p orbital of the N atom in the MEA molecule could coordinate with the 3d empty orbital of the Fe atom, forming a protective film on the metal surface, which plays a good anti-corrosion effect. This work not only enriched the study of non-aqueous LLCS but also expanded its potential applications in the field of lubrication.

A snowboard-inspired lubricating nanosystem with responsive drug release for osteoarthritis therapy

Most of present works of osteoarthritis (OA) therapy are focusing on reducing friction and improving drug loading capacity, while little attention is paid to realizing long-time lubrication and on-demand drug release. In this study, inspired by snowboards with good solid-liquid interface lubrication, a fluorinated graphene based nanosystem with dual functions of long-time lubrication and thermal-responsive drug release was constructed for OA synergetic therapy. An aminated polyethylene glycol bridging strategy was developed to enable covalent grafting of hyaluronic acid on fluorinated graphene. This design not only greatly increased the nanosystem's biocompatibility, but also reduced the coefficient of friction (COF) by 83.3 % compared to H₂O. The nanosystem showed long-time and steady aqueous lubrication behavior even after more than 24,000 times of friction tests, and a low COF of 0.13 was obtained with over 90% wear volume reduction. Diclofenac sodium was controllably loaded and sustained drug release was tuned by near-infrared light. Moreover, anti-inflammation results showed that the nanosystem had good protective effect on inhibiting OA deterioration, which could up-regulate cartilage anabolic genes of Col2α and aggrecan while down-regulating catabolic proteases genes of TAC1 and MMP1. This work constructs a novel dual-functional nanosystem that realizes friction and wear reduction with long lubrication life, and shows thermal-responsive on-demand drug release with good synergistic therapeutic effect of OA.

Organohydrogels with High-speed Lubrication via Confining Polymer Chain Mobility by Interpenetrated Heteronetwork

Hydrogels with pure hydrophilic network have received much attention due to their excellent low frictional behavior. However, the lubrication performance of hydrogels is not satisfied under high-speed condition due to the energy dissipation caused by adsorbed polymer chains as well as the failure of lubricating mechanisms accompanied by the transition of lubrication regime. In this work, interpenetrating double-network organohydrogels were constructed by combining hydrophilic and oleophilic polymer networks to modify the physiochemical properties of surface polymer chains, especially the chain mobility. The oleophilic polymer network spatially restricting the mobility of the swollen hydrophilic network in water, resulted in a low coefficient of friction (ca. 0.01) compared with conventional hydrogels at high speed (0.1m/s). Meanwhile, the organohydrogels had superior wear resistance, with almost no wear observed on the sliding track after 5k cycles of rubbing at high speed. The design concept of organohydrogels can be extended to a variety of low-wear, highly-lubricating materials.

The influence of ions on the lubricative abilities of mucin and the role of sialic acids

Mucus reduces friction between epithelial surfaces by providing lubrication in the boundary and mixed regime. Mucins, the main macromolecule, are heavily glycosylated proteins that polymerise and retain water molecules, resulting in a hydrated biogel. It is assumed that positively charged ions can influence mucin film structure by screening the electrostatic repulsions between the negatively charged glycans on mucin moieties and draw in water molecules via hydration shells. The ionic concentration can vary significantly in different mucus systems and here we show that increasing the ionic concentration in mucin films leads to an increase in lubrication between two polydimethylsiloxane surfaces at sliding contact in a compliant oral mimic. Mucins were found to bind sodium ions in a concentration-dependent manner and increased ionic concentration appears to cause mucin films to swell when assessed by Quartz Crystal hiMicrobalance with Dissipation (QCM-D) analysis. Furthermore, we determined that the removal of negatively charged sialic acid moieties by sialidase digestion resulted in reduced adsorption to hydrophilic surfaces but did not affect the swelling of mucin films with increasing ionic concentrations. Moreover, the coefficient of friction was increased with sialic acid removal, but lubrication was still increased with increasing ionic concentrations. Taken together this suggests that sialic acids are important for lubrication and may exert this through the sacrificial layer mechanism. Ionic concentration appears to influence mucin films and their lubrication, and sialic acids, at least partly, may be important for ion binding.

Enhanced multi-component model to consider the lubricant effect on compressibility and compactibility

Modeling of structural and mechanical tablet properties consisting of multiple components, based on a minimum of experimental data is of high interest, in order to minimize time- and cost-intensive experimental trials in the development of new tablet formulations. The majority of commonly available models use the compressibility and compactibility of constituent components and establish mixing rules between those components, in order to predict the tablet properties of formulations containing multiple components. However, their applicability is limited to single materials, which form intact tablets (e.g. lactose, cellulose) and therefore, they cannot be applied for lubricants. Lubricants are required in the majority of industrial tablet formulations and usually influence the mechanical strength of tablets. This study combines the multi-component compaction model of Reynolds et al. (2017) with a recently published lubrication model (Puckhaber et al. 2020) to describe the impact of multiple components on a formulation consisting of two diluents and a lubricant. By that, this model combination displays a meaningful extension of existing compaction models and allows the systematic prediction of properties of lubricated multi-component tablets.

Screening of lubricants towards their applicability for external lubrication

Internal lubrication is associated with decreasing tensile strength and prolonged disintegration. These effects can be minimized using external lubrication. In current study, six lubricants (magnesium stearate, sodium stearyl fumarate, stearic acid, glyceryl dibehenate, poloxamer 188 and sucrose monopalmitate) were processed with an external lubrication system implemented in a compaction simulator. The effect of process parameters related to the tableting process (main compaction pressure and tableting speed) and external lubrication system (spraying time, atomizing pressure and dust extraction system) on the responses was studied for a placebo formulation (80% mannitol - 20% microcrystalline cellulose). Internally lubricated blends (0.75 - 4%) were processed as reference. All lubricants proved successful in reducing ejection forces through external lubrication while yielding substantially lower lubricant concentrations compared to internal lubrication. No negative effect of external lubrication on tensile strength and disintegration time was observed, irrespective of lubricant type. Similar tensile strengths and disintegration times were measured for the different lubricants. This was in contrast to internal lubrication where a decrease in tensile strength and prolonged disintegration was generally observed. Additionally, the lubricant types affected tensile strength and disintegration differently. This study demonstrates the versatility of external lubrication as an alternative lubrication method for production of pharmaceutical tablets.

Intra-articular treatment of temporomandibular joint osteoarthritis by injecting actively-loaded meloxicam liposomes with dual-functions of anti-inflammation and lubrication

Temporomandibular joint (TMJ) osteoarthritis is a common osteochondral degenerative disease which can severely affect patient's mouth opening and mastication. Meloxicam (MLX), one of the most widely used non-steroidal anti-inflammatory drugs, is the main clinical therapy for the treatment of TMJ osteoarthritis. However, the clinical effect is greatly compromised because of its poor water solubility and high lipophilicity. In the present study, we developed an actively-loaded liposomal formulation, namely MLX-Ca(AC)₂Lipo, using meglumine to enhance aqueous solubility and divalent metal (Ca²⁺) solution to improve encapsulation efficiency. By the formation of the nano-bowl shaped MLX-Ca precipitates inside the liposomes, MLX-Ca(AC)₂Lipo successfully achieved an optimal encapsulation efficiency as high as 98.4% compared with previous passive loading method (60.6%). Additionally, MLX-Ca(AC)₂Lipo maintained stable, and the slow drug release not only prolonged the duration of drug efficacy but also improved bioavailability. It was shown in the in vitro and in vivo tests that MLX-Ca(AC)₂Lipo downregulated the synthesis of the inflammatory factors (such as prostaglandin-E2) and as a consequence reduced chondrocytes apoptosis and extracellular matrix degeneration. Furthermore, the intra-articular injection of MLX-Ca(AC)₂Lipo enhanced bioinspired lubrication of TMJ, protecting the cartilage from progressive wear. In summary, MLX-Ca(AC)₂Lipo with dual-functions of anti-inflammation and lubrication is a promising nanomedicine for the treatment of TMJ osteoarthritis by intra-articular injection.

Optimization techniques for energy efficiency in machining processes-a review

Metal working process is one of the main activities in mechanical manufacturing industry; it is considered as a major consumer of energy and natural resources. In material removal process, the selection of cutting parameters and cooling or cutting liquid is necessary to save energy and achieve energy efficiency as well as sustainability. During the last two decades, the number of publications in this field has rapidly increased and has shown the importance of this research area. This review paper identifies and reviews in detail a total of 166 scientific studies which exhibit original contributions to the field and address multiple energy efficiency challenges. The recently developed models of energy consumption and different materials used in the machining process are presented. Therefore, this study describes various techniques for modeling and optimizing machining operations such as turning, milling, and drilling. Modeling techniques, experimental methods, multi-objective and single-objective optimization methods, and hybrid techniques optimization are presented in a detailed manner compared to previous review papers where only energy models are discussed. It can help practitioners and researchers to select the most appropriate approach for the desired experience and to highlight the progress of these methods in terms of machining energy efficiency. Additionally, this paper provides a review of different cutting fluids adopted in machining processes. This paper assists researchers and manufacturers in making advantageous technical decisions that have substantial economics in terms of energy saving.

Recombinant mucin biotechnology and engineering

Mucins represent a largely untapped class of polymeric building block for biomaterials, therapeutics, and other biotechnology. Because the mucin polymer backbone is genetically encoded, sequence-specific mucins with defined physical and biochemical properties can be fabricated using recombinant technologies. The pendent O-glycans of mucins are increasingly implicated in immunomodulation, suppression of pathogen virulence, and other biochemical activities. Recent advances in engineered cell production systems are enabling the scalable synthesis of recombinant mucins with precisely tuned glycan side chains, offering exciting possibilities to tune the biological functionality of mucin-based products. New metabolic and chemoenzymatic strategies enable further tuning and functionalization of mucin O-glycans, opening new possibilities to expand the chemical diversity and functionality of mucin building blocks. In this review, we discuss these advances, and the opportunities for engineered mucins in biomedical applications ranging from in vitro models to therapeutics.

Evaluation of Alternative Metallic Stearates as Lubricants in Pharmaceutical Tablet Formulation

Magnesium stearate (MgSt) is perhaps one of the most frequently used lubricants in tablet formulation due to its superior lubrication capacity, yet it could also negatively affect the critical quality attributes of pharmaceutical products. Therefore, we provided a rather comprehensive evaluation of another two FDA-approved metallic stearates, sodium stearate (NaSt) and calcium stearate (CaSt), as alternative tablet lubricants. The primary objective of the present study is to comparatively evaluate the physicochemical properties and lubrication efficiency of the three metallic stearates. In addition, it was also aimed to specify the most influential factor for ranking and differentiating the lubricity of various lubricants using principal component analysis. Unit ejection force could be used herein as a simple and the most powerful parameter to evaluate the lubrication performance instead of the friction coefficient. The results suggested that CaSt, MgSt, and NaSt had similar impacts on the mechanical strength of tablets. However, CaSt exhibited insufficient lubrication effects as the formulations containing CaSt showed low pressure transmission ratios, high unit ejection forces, and high friction coefficients. In contrast, both MgSt and NaSt displayed satisfactory lubrication efficiency without negatively impacting tabletability. Notably, the lubrication performance of the formulation containing 0.5 wt% NaSt was almost identical to that of the formulation with 1 wt% MgSt, indicating that NaSt had a remarkable lubrication capability probably due to its high specific surface area. In summary, the findings of this investigation should provide practical information and feasible methodologies to readily determine the lubricity and to sensibly select alternative lubricants for pharmaceutical tablet formulations.

Impact of alternative lubricants on process and tablet quality for direct compression

Internal lubrication with magnesium stearate (MgSt) is associated with a reduced tensile strength and prolonged disintegration and dissolution times. In the current study, alternative lubricants to MgSt were compared with regard to lubrication efficacy and their impact on tablet properties. The lubricants were combined in different concentrations (0.5-5% w/w) with three fillers (lactose, mannitol and microcrystalline cellulose (MCC)). The high lubrication efficiency of MgSt was associated with the highest reduction of tensile strength. The micronized stearic acid (SA) grades proved good alternatives as they showed a good lubrication efficiency in combination with a limited negative effect on tensile strength. The hydrophobic lubricants (e.g., MgSt and SA) did not prolong disintegration. In contrast, delayed disintegration was observed for sucrose monopalmitate combined with all three fillers and for several other hydrophilic lubricants (sodium lauryl sulfate, poloxamers 188 and P407) combined with MCC. These unexpected findings were explained by the competition-for-water hypothesis. The potential of alternative lubricants to MgSt was demonstrated in this study. Nevertheless, the impact of lubricant addition on process and tablet quality depended on lubricant (type and concentration) and formulation (lubrication need, deformation mechanism and disintegration behavior) properties. Therefore, lubricant selection should be carefully considered in formulation development.

Nanofat functionalized injectable super-lubricating microfluidic microspheres for treatment of osteoarthritis

Nanofat (NF) is a fine emulsion that has been used to treat a variety of diseases given its abundance of bioactive components. However, the biological functions of NF have been limited due to its inability to localize during implantation. In this study, NF was immobilized in microfluidic-generated aldehyde-modified polylactic glycolic acid (PLGA) porous microspheres (PMs) via Schiff base condensation and non-covalent binding in a three-dimensional (3D) porous network (PMs@NF). The PMs effectively enhanced the cartilage-targeted retention efficiency of NF, which also resulted in remarkable lubrication performance, with the friction coefficient being reduced by ∼80%, which was maintained over time. Meanwhile, the 3D penetrating structure of the microspheres stimulated cytokine secretion by the NF-derived stem cells, upregulating the expression of anabolism-related genes and downregulating catabolism, and the expression of inflammation-related and pain-related genes. Injecting PMs@NF into the knee joint cavity of a rat model with destabilization of the medial meniscus (DMM) reduced osteophyte formation and protected the cartilage from degeneration, thereby inhibiting the progression of osteoarthritis and improving animal behavior. In summary, this study developed a multifunctional platform with NF immobilization and super-lubrication, which showed great potential for the minimally invasive treatment of osteoarthritis.

Dopamine-conjugated hyaluronic acid delivered via intra-articular injection provides articular cartilage lubrication and protection

Due to its high molecular weight and viscosity, hyaluronic acid (HA) is widely used for viscosupplementation to provide joint pain relief in osteoarthritis. However, this benefit is temporary due to poor adhesion of HA on articular surfaces. In this study, we therefore conjugated HA with dopamine to form HADN, which made the HA adhesive while retaining its viscosity enhancement capacity. We hypothesized that HADN could enhance cartilage lubrication through adsorption onto the exposed collagen type II network and repair the lamina splendens. HADN was synthesized by carbodiimide chemistry between hyaluronic acid and dopamine. Analysis of Magnetic Resonance (NMR) and Ultraviolet spectrophotometry (Uv-vis) showed that HADN was successfully synthesized. Adsorption of HADN on collagen was demonstrated using Quartz crystal microbalance with dissipation (QCM-D). Ex vivo tribological tests including measurement of coefficient of friction (COF), dynamic creep, in stance (40 N) and swing (4 N) phases of gait cycle indicated adequate protection of cartilage by HADN with higher lubrication compared to HA alone. HADN solution at the cartilage-glass sliding interface not only retains the same viscosity as HA and provides fluid film lubrication, but also ensures better boundary lubrication through adsorption. To confirm the cartilage surface protection of HADN, we visualized cartilage wear using optical coherence tomography (OCT) and atomic force microscopy (AFM).

Mechanisms of the association between PTSD and sexual arousal and lubrication functioning among trauma-exposed female service members/veterans

BACKGROUND

The presence of a post-traumatic stress disorder (PTSD) diagnosis or higher PTSD severity is associated with higher overall sexual dysfunction in female service members/veterans. However, the mechanisms linking PTSD to specific components of women's sexual arousal function, like lubrication and mental arousal, are unknown.

METHODS

We conducted a survey among 464 women who reported probable Criterion A exposure for PTSD. Path analysis examined (1) the association of PTSD with sexual arousal, (2) whether specific PTSD symptom clusters were uniquely associated with sexual arousal, and (3) whether this association is indirect, through the effects of higher depression severity and lower romantic relationship satisfaction. Arousal was operationalized to measure both mental (subjective arousal) and physical (lubrication) experiences.

RESULTS

Higher PTSD severity was associated with lower lubrication and arousal function. The association of PTSD severity with arousal was indirect, through lower romantic relationship satisfaction (estimate: -0.12; 95% CI: [-0.014, -0.007]) and higher depression (estimate: -0.08, 95% CI: [-0.012, -0.002]). The association of PTSD severity with lubrication was also indirect, but only through lower relationship satisfaction (estimate: -0.10, 95% CI: [-0.013, -0.006]). PTSD symptom clusters were not uniquely associated with arousal and lubrication through mediated pathways.

LIMITATIONS

Data were from a cross-sectional study using a convenience sample. Criterion A exposure could not be confirmed.

CONCLUSIONS

PTSD may lead to arousal and lubrication dysfunction by contributing to higher depression severity and strained romantic relationships. Interventions targeting reductions in depressive symptoms and bolstering relationship satisfaction may minimize the burden of PTSD on sexual arousal concerns.

Prediction of the impact of lubrication on tablet compactibility

The tableting of most pharmaceutical formulations requires the addition of lubricants to reduce ejection forces, prevent tooling damage and tablet defects. The internal addition of lubricants is known to reduce tablet tensile strength, especially of mainly plastically deforming materials. To date, available models show only limited quantitative predictive accuracy for the influence of lubricant concentration on the mechanical strength of tablets. This study aims to fill this gap and present a model based on the Ryshkewitch-Duckworth equation that can estimate the compactibility profiles of lubricated formulations. Binary mixtures of different diluents (microcrystalline cellulose and lactose) were prepared with common lubricants (magnesium stearate and sodium stearyl fumarate) and subsequently tableted. The resulting compactibility profiles were fitted using the Ryshkewitch-Duckworth equation and the derived fit parameters (k_b and σ₀) were correlated with the lubricant concentration. Subsequently, an empirical model was established which requires a minimum of experimental data and is able to predict the tensile strength of lubricated diluent tablets. Consequently, the developed empirical model is an interesting and valuable addition to the existing multi-component compacting models available and offers the opportunity to accelerate experimentation in the development of new tablet formulations.

When to start tacrolimus ointment for vernal keratoconjunctivitis? A proposed treatment protocol

PURPOSE

The aim of this study was to compare treatment regimens of tacrolimus and of topical steroids for VKC and suggest a treatment protocol according to our clinical experience.

METHODS

This retrospective, nonrandomized case series enrolled 85 patients with VKC. Patients were classified clinically according to severity (mild, moderate, severe) and were treated according to a suggested protocol. Analysis was made according to treatment received: tacrolimus ointment as first line treatment (tacrolimus 1st line), tacrolimus ointment after topical steroid drops treatment (tacrolimus 2nd line) and topical steroid drops or artificial tears alone (topical steroid and tears group).

RESULTS

Significant improvements in clinical signs and symptoms were achieved under tacrolimus treatment 14 months in the moderate group and 5 months in the severe group. The longest duration of treatment was for tacrolimus 2nd line group (p = 0.031) and the mean number of visits in the clinic was the highest. The mean number of topical treatments per day was higher in the topical steroid and tears group (2.6 times) than in the two tacrolimus groups (1.3 times for both). The mean time needed to achieve disease remission or relief did not differ between the tacrolimus 1st line and 2nd line groups.

CONCLUSION

Tacrolimus treatment is effective and safe for VKC. Tacrolimus as 1st line treatment may be preferred for severe cases, for faster disease remission compared to tacrolimus as 2nd line treatment; and with fewer topical treatments per day compared to topical steroids.

Zwitterionic polymer modified xanthan gum with collagen II-binding capability for lubrication improvement and ROS scavenging

High friction of damaged cartilage requires long-acting lubricated additive, which can also effectively scavenge reactive oxidative species (ROS) produced by mechanically stimulated chondrocytes. In this study, xanthan gum (XG) was grafted by poly (sulfobetaine methacrylate) (PSBMA) (the [XG]/[SBMA] molar ratio is 1:5 or 1:10), forming nanoparticles and then conjugated with collagen II-binding peptide, finally obtaining CBPXGSB1/5 or CBPXGSB1/10. Therein, the CBPXGSB1/5 was chosen as optimal lubricated additive. The results show that hydrated effect of PSBMA side chains endows CBPXGSB1/5 with favorable lubrication property (COF is 0.063). Furthermore, the CBPXGSB1/5 combining lubrication property and specific binding capability together may achieve the long-acting lubrication for injured cartilage in medical field. The CBPXGSB1/5 also possesses antioxidation verified by DPPH assay and exhibits synergistically enhanced ROS (OH, O₂^- and H₂O₂) scavenging. Besides, cytotoxicity experiment demonstrates that CBPXGSB1/5 has good biocompatibility. Therefore, multifunctional CBPXGSB1/5 developed here may have promising application potential in osteoarthritis treatment.

The Lost Penis Syndrome: A New Clinical Entity in Sexual Medicine

INTRODUCTION

The "lost penis syndrome" (LPS) is a term often used in non-clinical settings to describe the subjective perception of the loss of cutaneous and proprioceptive feelings of the male organ during vaginal penetration. Although deserving clinical attention, this syndrome did not receive any consideration in the medical literature. Notwithstanding, it represents a relatively unexceptional condition among patients in sexual medicine clinics, and it is often reported together with other sexual dysfunctions, especially delayed ejaculation, anejaculation, male anorgasmia and inability to maintain a full erection.

OBJECTIVES

To draft a new conceptual characterization of the LPS, defined as a lack of penile somesthetic sensations during sexual penetration due to various causes and leading to several sexual consequences in both partners.

METHODS

Based on an extensive literature review and physiological assumptions, the mechanisms contributing to friction during penovaginal intercourse, and their correlation to LPS, have been explored, as well as other nonanatomical factors possibly contributing to the loss of penile sensations.

RESULTS

Efficient penile erection and sensitivity, optimal vaginal lubrication and trophism contribute to penovaginal friction. Whenever one of these processes does not occur, loss of penile sensation defined as LPS can occur. Sociocultural, psychopathological and age-related (ie, couplepause) factors are also implicated in the etiology. Four types of LPS emerged from the literature review: anatomical and/or functional, behavioral, psychopathological and iatrogenic. According to the subtype, a wide variety of treatments can be employed, including PDE5i, testosterone replacement therapy and vaginal cosmetic surgery, as well as targeted therapy for concomitant sexual comorbidity.

CONCLUSION

We held up the mirror on LPS as a clinically existing multifactorial entity and provided medical features and hypotheses contributing to or causing the occurrence of LPS. In the light of a sociocultural and scientific perspective, we proposed a description and categorization of this syndrome hypothesizing its usefulness in daily clinical practice. Colonnello E, Limoncin E, Ciocca G, et al. The Lost Penis Syndrome: A New Clinical Entity in Sexual Medicine. Sex Med Rev 2021;XX:XXX-XXX.

A novel biosurfactant producing Kocuria rosea ABR6 as potential strain in oil sludge recovery and lubrication

Biosurfactants are amphiphilic molecules composed of a hydrophilic and hydrophobic moiety and had the ability to penetrate into different phases to reduce the surface tension. This features caused to oil recovery, lubrication and facilities of crude oil in pipeline. In current research Biosurfactant-producing strain was isolated from the storage tanks of the Isfahan Oil Refining Company in Iran, and screened by oil expansion test, droplet collapse, and surface tension reduction measurement. Hydrocarbon recovery from crude oil sludge was measured under constant conditions. The effect of factoring biosource lubrication on crude oil in pipelines was investigated in vitro. Also, the optimization of biosurfactant production in different conditions was measured as a single factor and using Response Surface Method (RSM). The best biosurfactant-producing bacterium was identified as Kocuria rosea ABR6, and its sequence was registered in the gene bank with access number of MK100469. Chemical analysis proved that the produced biosurfactant was a lipopeptide. 7% of crude oil was recovered from petroleum sludge by biosurfactant obtained from Kocuria rosea ABR6. Also, the speed of crude oil transfer in pipelines was upgraded as it could be said that for a certain distance the transfer time reduced from 64 to 35 s. The highest biosurfactant production was measured at pH 9, aeration rate of 120 rpm and 96 h after incubation. The use of biosurfactants produced by Kocuria rosea ABR6 is recommended to remove oil sludge and lubricate oil in pipelines recommended in the oil industry.

Slow-release lubrication of artificial joints using self-healing polyvinyl alcohol/polyethylene glycol/ graphene oxide hydrogel

New fabrication methods and lubrication materials must be developed to improve the lubrication performance of artificial joints and increase the lubrication duration. Herein, a novel polyvinyl alcohol/polyethylene glycol/graphene oxide (PVA/PEG/GO) hydrogel was prepared by a physical cross-linking method, and then the hydrogel and its sustained-release solution were used as lubricant for friction evaluation. The results demonstrated that the slow-release gel solution has good lubrication performance, and coefficient of friction (COF) is only 0.04, which is much lower than the COF of distilled water (about 0.08) under the same conditions. The structure characterization results revealed that no new materials are formed in the gel. The results of thermogravimetric analyses and differential scanning calorimetry demonstrated that the addition of GO may improve the network crosslinking structure of the PVA/PEG hydrogel and improve its mechanical strength. In addition, PVA/PEG/GO hydrogel has superior self-healing function. The self-healing hydrogel did not break again after being pulled under 200 G of weights. The PVA/PEG/GO hydrogel with excellent slow-release lubricating performance and self-healing properties provides a novel candidate for design of long-term lubricating artificial joints, and is expected to promote the progress of artificial joint lubrication applications.

Female sexual dysfunction in multiple system atrophy: a prospective cohort study

Purpose

The diagnosis of probable multiple system atrophy relies on the presence of severe cardiovascular or urogenital autonomic failure. Erectile dysfunction is required to fulfil the latter criterion in men, whereas no corresponding item is established for women. In this study, we aimed to investigate sexual dysfunction in women with multiple system atrophy.

Methods

We administered the Female Sexual Function Index questionnaire and interviewed women with multiple system atrophy and age-matched controls regarding the presence of “genital hyposensitivity.”

Results

We recruited 25 women with multiple system atrophy and 42 controls. Female Sexual Function Index scores in sexually active women with multiple system atrophy were significantly lower (multiple system atrophy = 10; 15.4, 95% CI [10.1, 22.1], controls = 37; 26.1 [24.1, 28.1], p = 0.0004). The lowest scores concerned the domains of desire, arousal and lubrication. Genital hyposensitivity was reported by 56% of the patients with multiple system atrophy and 9% controls (p < 0.0001).

Conclusions

Sexual dysfunction is highly prevalent in women with multiple system atrophy. Screening for disturbances in specific sexual domains should be implemented in the clinical evaluation of women with suggestive motor symptoms.

Experimental investigation and modelling of tensile strength of pharmaceutical tablets based on shear force applied by feed frame paddles

The feed frame is an essential device used in a rotary tablet press and it improves the performance of the powder filling process into dies. However, the feed frame affects critical quality attributes such as a tensile strength and a dissolution negatively due to a shear applied to powders from feed frame paddles, leading to over-lubrication. This effects may be significant for shear sensitive materials. The work focuses on the effect of tablet press parameters (die disk speed and feed frame speed) and mixture composition (amount of magnesium stearate) on the tensile strength and the prediction of the tensile strength by considering the extent of shear. It is found that within the investigated range of tablet press parameters and the amount of magnesium stearate, the feed frame speed and the amount of magnesium stearate have an impact on the tensile strength. Furthermore, a lubrication model based on the extent of shear is presented to predict the decreasing trend of the tensile strength of tablets during tableting process and the results demonstrate that the prediction of tensile strength is in good agreement with experimental measurements.

Self-adhesive lubricated coating for enhanced bacterial resistance

Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants. Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported, the harsh and tedious synthesis greatly compromises their application, and more importantly, the bacterial resistance property has seldom been investigated in combination with the lubrication property. In this study, bioinspired by the performances of mussel and articular cartilage, we successfully synthesized self-adhesive lubricated coating and simultaneously achieved optimal lubrication and bacterial resistance properties. Additionally, we reported the mechanism of bacterial resistance on the nanoscale by studying the adhesion interactions between biomimetic coating and hydrophilic/hydrophobic tip or living bacteria via atomic force microscopy. In summary, the self-adhesive lubricated coating can effectively enhance lubrication and bacterial resistance performances based on hydration lubrication and hydration repulsion, and represent a universal and facial strategy for surface functionalization of biomedical implants.

Exploring the lubrication mechanisms of synovial fluids for joint longevity - A perspective

Synovial fluids are complex fluids responsible for the exceptional lubrication present in synovial joints. These fluids consist of various constituents, including hyaluronic acid, surface-active proteins (i.e., lubricin), surface-active phospholipids, as well as various other proteins such as human serum albumin and γ -globulin seric proteins, each of them playing an essential role in lubrication. Being the key to the most efficient biotribological systems, this article is intended to review the current understanding of the underlying lubrication mechanisms of the synovial fluids enables prospective usage in numerous applications, especially as a lubricant for hip and knee prosthetics in combatting osteoarthritis. Current research focuses on the determination of the role of proteins in prosthetic lubrication, optimal material combinations for prosthesis, and the effects of relevant physical variables in prosthetic lubrication. The characterization of prosthetic lubrication and wear mechanisms by synovial fluids represents a prominent challenge in tribological research, yet also an important hurdle to overcome towards optimal lubrication of articular prosthetics.

Investigation of synovial fluid lubricants and inflammatory cytokines in the horse: a comparison of recombinant equine interleukin 1 beta-induced synovitis and joint lavage models

BACKGROUND

Lameness is a debilitating condition in equine athletes that leads to more performance limitation and loss of use than any other medical condition. There are a limited number of non-terminal experimental models that can be used to study early inflammatory and synovial fluid biophysical changes that occur in the equine joint. Here, we compare the well-established carpal IL-1β-induced synovitis model to a tarsal intra-articular lavage model, focusing on serial changes in synovial fluid inflammatory cytokines/chemokines and the synovial fluid lubricating molecules lubricin/proteoglycan 4 and hyaluronic acid. The objectives of this study were to evaluate clinical signs; synovial membrane and synovial fluid inflammation; and synovial fluid lubricants and biophysical properties in response to carpal IL-1β synovitis and tarsal intra-articular lavage.

RESULTS

Hyaluronic acid (HA) concentrations, especially high molecular weight HA, and synovial fluid viscosity decreased after both synovitis and lavage interventions. Synovial fluid lubricin concentrations increased 17-20-fold for both synovitis and lavage models, with similar changes in both affected and contralateral joints, suggesting that repeated arthrocentesis alone resulted in elevated synovial fluid lubricin concentrations. Synovitis resulted in a more severe inflammatory response based on clinical signs (temperature, heart rate, respiratory rate, lameness and joint effusion) and clinicopathological and biochemical parameters (white blood cell count, total protein, prostaglandin E2, sulfated glycosaminoglycans, tumor necrosis factor-α and CC chemokine ligands - 2, - 3, - 5 and - 11) as compared to lavage.

CONCLUSIONS

Synovial fluid lubricin increased in response to IL-1β synovitis and joint lavage but also as a result of repeated arthrocentesis. Frequent repeated arthrocentesis is associated with inflammatory changes, including increased sulfated glycosaminoglycan concentrations and decreased hyaluronic acid concentrations. Synovitis results in more significant inflammatory changes than joint lavage. Our data suggests that synovial fluid lubricin, TNF-α, CCL2, CCL3, CCL5, CCL11 and sGAG may be useful biomarkers for synovitis and post-lavage joint inflammation. Caution should be exercised when performing repeated arthrocentesis clinically or in experimental studies due to the inflammatory response and loss of HA and synovial fluid viscosity.

Evaluation of the influence of whole-body cryotherapy on selected skin parameters in healthy individuals: Pilot study

INTRODUCTION

The aim of the paper was to evaluate changes in selected skin parameters (hydration, sebum level and pH of the skin) after whole-body cryotherapy (WBC).

MATERIAL AND METHODS

The study encompassed of 16 individuals (8 men and 8 women), who participated in 15 WBC sessions. There were 4 measurements of skin parameters performed in the following way: prior to the first cryotherapy session, directly after the first session, after the 15th session, and after 3 weeks from the moment when the therapy was discontinued.

RESULTS

No significant differences were observed for hydration and skin pH. Sebum level significantly decreased after 2nd cryotherapy session.

CONCLUSION

Whole-body cryotherapy seems to be safe for skin.

Lubrication Practices and Receptive Anal Sex: Implications for STI Transmission and Prevention

Introduction

Implications of lubricant use in men having sex with men (MSM) are poorly characterized, particularly associations with sexual behavior and rectal sexually transmitted infection (STI) risk.

Aim

We sought to clarify covariates associated with lubrication type including differing sexual preferences and rectal STI prevalence.

Methods

Primary English-speaking individuals ≥18 years old visiting San Francisco City Clinic (SFCC) between April and May of 2018 who endorsed lubricant use during receptive anal sex within the last 3 months were studied. Associations between lubrication type used and collected covariates were assessed using Kruskal-Wallis analysis of variance for continuous variables and Chi-squared test for categorical variables. We used logistic regression to examine the association between lubrication type and rectal STI test result.

Main Outcome Measures

Rectal STI test positivity.

Results

From all enrolled participants, 179 completed the survey and endorsed use of a lubricant during receptive anal sex within the last 3 months. Silicone lubricant users had the most sexual partners in the last 3 months (13 [mean] ± 30 [SD], P= .0003) and were most likely to have a history of gonorrhea. Oil-based lubricant users had the most partners with whom they had receptive anal sex in the last 3 months (7 ± 6, P= .03). Water-based lubricant users most commonly used a condom in their last sexual encounter and had the fewest sexual partners in the last 3 months (4 ± 4, P= .0003). Spit/saliva lubricant use was associated with positive rectal STI result.

Conclusion

Silicone and oil-based lubricant users were more likely to report condomless receptive anal sex and to have a history of gonorrhea while spit/saliva lubricant use associated with positive rectal STI acquisition. Lee A, Gaither TW, Langston ME, et al. Lubrication Practices and Receptive Anal Sex: Implications for STI Transmission and Prevention. Sex Med 2021;9:100341.

Cartilage lamina splendens inspired nanostructured coating for biomaterial lubrication

Biomaterials that are used in biological systems, such as polycarbonate urethane (PCU) knee joint implants and contact lenses, generally lack lubrication. This limits their integration with the body and impedes their function. Here, we propose a nanostructured film based on hydrophilic polysaccharide hyaluronic acid conjugated with dopamine (HADN) and zwitterionic reduced glutathione (Glu), which forms a composite coating (HADN-Glu) to enhance the lubrication between cartilage and PCU. HADN was synthesized by carbodiimide chemistry between hyaluronic acid and dopamine and deposited on PCU surface under mild oxidative conditions. Then, zwitterionic peptide-reduced glutathione was bioconjugated to HADN, forming a lubrication film. Analysis based on X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and wettability indicated that HADN and Glu had grafted successfully onto the PCU surface. Measurements of the coefficient of friction (COF), friction energy dissipation and cartilage roughness indicated that cartilage was effectively protected by the high lubrication of HADN-Glu. Both at low and high applied loads, this effect was likely due to the enhanced boundary lubrication enabled by HADN-Glu on the PCU surface. Moreover, HADN-Glu is highly biocompatible with chondrocyte cells, suggesting that this film will benefit the design of implants where lubrication is needed.

The role of synovial fluid constituents in the lubrication of collagen-glycosaminoglycan scaffolds for cartilage repair

Extracellular matrix (ECM)-derived scaffolds have shown promise as tissue-engineered grafts for promoting cartilage repair. However, there has been a lack of focus on fine-tuning the frictional properties of scaffolds for cartilage tissue engineering as well as understanding their interactions with synovial fluid constituents. Proteoglycan-4 (PRG4) and hyaluronan (HA) are macromolecules within synovial fluid that play key roles as boundary mode lubricants during cartilage surface interactions. The overall objective of this study was to characterize the role PRG4 and HA play in the lubricating function of collagen-glycosaminoglycan (GAG) scaffolds for cartilage repair. As a first step towards this goal, we aimed to develop a suitable in vitro friction test to establish the boundary mode lubrication parameters for collagen-GAG scaffolds articulated against glass in a phosphate buffered saline (PBS) bath. Subsequently, we sought to leverage this system to determine the effect of physiological synovial fluid lubricants, PRG4 and HA, on the frictional properties of collagen-GAG scaffolds, with scaffolds hydrated in PBS and bovine synovial fluid (bSF) serving as negative and positive controls, respectively. At all compressive strains examined (ε = 0.1-0.5), fluid depressurization within hydrated collagen-GAG scaffolds was >99% complete at ½ minute. The coefficient of friction was stable at all compressive strains (ranging from a low 0.103 ± 0.010 at ε = 0.3 up to 0.121 ± 0.015 at ε = 0.4) and indicative of boundary-mode conditions. Immunohistochemistry demonstrated that PRG4 from recombinant human (rh) and bovine sources adsorbed to collagen-GAG scaffolds and the coefficient of friction for scaffolds immersed in rhPRG4 (0.067 ± 0.027) and normal bSF (0.056 ± 0.020) solution decreased compared to PBS (0.118 ± 0.21, both p < 0.05, at ε = 0.2). The ability of the adsorbed rhPRG4 to reduce friction on the scaffolds indicates that its incorporation within collagen-GAG biomaterials may enhance their lubricating ability as potential tissue-engineered cartilage replacements. To conclude, this study reports the development of an in vitro friction test capable of characterizing the coefficient of friction of ECM-derived scaffolds tested in a range of synovial fluid lubricants and demonstrates frictional properties as a potential design parameter for implants and materials for soft tissue replacement.

A Scale-Up, Phenomenological Model Incorporating the Effect of Both Feed Frame Lubrication and Tumble Blending-Driven Lubrication on Tablet Mechanical Strength

In tablet manufacturing, mixing operations in tumble blending (TB) and in the feed frame (FF) of the rotary press can both increase lubricity, negatively influencing the tablet mechanical strength. While the TB-driven lubrication was systematically studied, no reliable bench-scale methods exist for the effect of FF lubrication. Because TB and FF mixing are usually two successive operations in tablet manufacturing, we developed a phenomenological model to incorporate the impact of TB-driven lubrication and the FF lubrication on the tablet tensile strength (TS). We noted that exponential decay functions can describe the evolution of the tablet TS as the function of the extent of TB, as well as the residence time in FF. Hence, the overall lubrication sensitivity can be modeled by incorporating two distinct exponential decay functions. The model can be calibrated through bench-scale experiments. Using an investigational powder blend, we showed that this approach accurately predicted the tablet TS in a scale-up tablet compression study, thereby verifying its utility. This model can serve as a scale-up diagnostic and risk-assessment tool, with the ability to adjust the overall effect of lubrication by changing the TB scale and the FF residence time commensurate with the large-scale operations.

Sexual Function of Men and Women With Spina Bifida: A Scoping Literature Review

INTRODUCTION

As most adults with spina bifida are either sexually active or interested in becoming sexually active, providers should understand how spina bifida impacts sexual function and options for treatment.

OBJECTIVES

The objective of this study is to summarize the current literature describing how features of spina bifida impact sexual function in men and women, effective available treatment options for sexual dysfunction, and to identify research gaps.

METHODS

Searches were conducted in PubMed, CINAHL Complete, PsychInfo, Cochrane Central, Scopus, and Web of Science Core Collection databases using keywords related to spina bifida and sexual function. 34 primary research studies were included.

RESULTS

Most men (56-96%) can achieve an erection, although it may be insufficient for penetration. Although 50-88% ejaculate, it is often dripping, retrograde, or insensate. Twenty percent to 67% achieve orgasm. Generally, men with lower lesions and intact sacral reflexes have better outcomes, although some men with all levels of lesion report good function. Sildenafil is efficacious at treating erectile dysfunction for most men. The "TO-MAXimize sensation, sexuality, and quality of life" procedure may improve sexual function in selected men with low-level lesions. Female sexual function and treatment is less well understood. Women may experience decreased arousal, difficulties with orgasm, and pain. No treatment has been studied in women. Bowel and bladder incontinence during intercourse appears to be bothersome to men and women. Although both men and women have diminished sexual satisfaction, their sexual desire appears to be least impacted. Present studies are limited by studies' small, heterogeneous populations, the misuse of validated questionnaires in the sexually inactive population, and the lack of a validated questionnaire specific to people with spina bifida.

CONCLUSIONS

Spina bifida impacts the sexual function of both men and women. Future studies should seek a better understanding of female sexual function and treatment, use validated questionnaires appropriately, and ultimately create a validated sexual function questionnaire specific to this population. Streur CS, Corona L, Smith JE, et al. Sexual Function of Men and Women With Spina Bifida: A Scoping Literature Review. Sex Med Rev 2021;9:244-266.

Management of corneal ulceration with a moisture chamber due to temporary lagophthalmos in a brain injury patient: A case report

BACKGROUND

This study describes the use of a moisture chamber to treat corneal ulceration due to temporary lagophthalmos in a critically ill patient.

CASE SUMMARY

A 46-year-old woman was admitted to the intensive care unit after a car accident. She suffered multiple injuries that included brain injury and presented with moderately decreased consciousness and lagophthalmos in her right eye. Within 6 d, her consciousness improved considerably; at which time, exposure keratopathy occurred and worsened to corneal ulceration. Lubricating gel, antibiotic ointment, and bandage contact lens were all ineffective in preventing or treating the exposure keratopathy. Instead of tarsorrhaphy, a moisture chamber was applied which successfully controlled the corneal ulceration. The moisture chamber was discontinued when complete eyelid closure recovered a week later.

CONCLUSION

A moisture chamber may be an effective, noninvasive alternative to tarsorrhaphy for treating severe exposure keratopathy due to temporary lagophthalmos.

Linking polymer hydrophobicity and molecular interactions to rheology and tribology in phospholipid-containing complex gels

HYPOTHESIS

The rheological behavior and frictional properties (macroscopic level) of systems containing a hydrophobically modified polymer and phospholipids depend on the hydrophobic association that occur between the hydrophobic moiety of the polymer and the phospholipid tails (molecular level). The hydrophobicity of the polymer can thus be used to control its interactions with phospholipids, and manipulate complex gel macroscopic behavior.

EXPERIMENTS

By using systems composed of a crosslinked hydrophobically modified polyacrylic acid (HMPAA) or a crosslinked polyacrylic acid polymer (PAA) and phospholipids, we examine the underlying mechanisms through which the components interact using isothermal titration calorimetry (ITC) and their effect on rheological and tribological characteristics of complex gels.

FINDINGS

We find the systems containing HMPAA and phospholipid exhibit gel-like behavior with the elastic modulus increasing substantially upon phospholipid addition due to hydrophobic interactions that result in a more interconnected network formation, as evidenced by ITC measurements. Similar experiments with a crosslinked polyacrylic acid polymer (PAA) show no interactions, lending credence to our hypothesis. In addition, soft tribological behavior shows lower friction coefficients at low entrainment speeds with HMPAA concentration and the addition of phospholipid, while no change in friction coefficient was observed in the case of increasing PAA concentration, indicating HMPAA and phospholipids to be interacting with the soft PDMS contacts.

Surface adsorption and lubrication properties of plant and dairy proteins: A comparative study

The aim of this work was to compare the surface adsorption and lubrication properties of plant and dairy proteins. Whey protein isolate (WPI) and pea protein isolate (PPI) were chosen as model animal and plant proteins, respectively, and various protein concentrations (0.1-100 mg/mL) were studied with/without heat treatment (90 °C/60 min). Quartz crystal microbalance with dissipation monitoring (QCM-D) experiments were performed on hydrophilic (gold) and hydrophobic polydimethylsiloxane (PDMS) sensors, with or without a mucin coating, latter was used to mimic the oral surface. Soft tribology using PDMS tribopairs in addition to wettability measurements, physicochemical characterization (size, charge, solubility) and gel electrophoresis were performed. Soluble fractions of PPI adsorbed to significantly larger extent on PDMS surfaces, forming more viscous films as compared to WPI regardless of heat treatment. Introducing a mucin coating on a PDMS surface led to a decrease in binding of the subsequent dietary protein layers, with PPI still adsorbing to a larger extent than WPI. Such large hydrated mass of PPI resulted in superior lubrication performance at lower protein concentration (≤10 mg/mL) as compared to WPI. However, at 100 mg/mL, WPI was a better lubricant than PPI, with the former showing the onset of elastohydrodynamic lubrication. Enhanced lubricity upon heat treatment was attributed to the increase in apparent viscosity. Fundamental insights from this study reveal that pea protein at higher concentrations demonstrates inferior lubricity than whey protein and could result in unpleasant mouthfeel, and thus may inform future replacement strategies when designing sustainable food products.

The challenge of lubricant-replenishment on lubricant-impregnated surfaces

Lubricant-impregnated surfaces are two-component surface coatings. One component, a fluid called the lubricant, is stabilized at a surface by the second component, the scaffold. The scaffold can either be a rough solid or a polymeric network. Drops immiscible with the lubricant, hardly pin on these surfaces. Lubricant-impregnated surfaces have been proposed as candidates for various applications, such as self-cleaning, anti-fouling, and anti-icing. The proposed applications rely on the presence of enough lubricant within the scaffold. Therefore, the quality and functionality of a surface coating are, to a large degree, given by the extent to which it prevents lubricant-depletion. This review summarizes the current findings on lubricant-depletion, lubricant-replenishment, and the resulting understanding of both processes. A multitude of different mechanisms can cause the depletion of lubricant. Lubricant can be taken along by single drops or be sheared off by liquid flowing across. Nano-interstices and scaffolds showing good chemical compatibility with the lubricant can greatly delay lubricant depletion. Often, depletion of lubricant cannot be avoided under dynamic conditions, which warrants lubricant-replenishment strategies. The strategies to replenish lubricant are presented and range from spraying or stimuli-responsive release to built-in reservoirs.