Pigment Dispersion Research Articles

Overlap syndrome: a case series and literature review of concurrent pigment dispersion and pseudoexfoliation syndromes.

The purpose of this review is to present two cases of overlap syndrome, or concurrent pigment dispersion syndrome and pseudoexfoliation syndrome. The summary of existing literature highlights the importance of accurate diagnosis and potential treatment options of overlap syndrome. The cases describe two patients with overlap syndrome and resulting progressive glaucoma. The condition tends to present after age 50 years old, with presence of both pseudoexfoliative material and pigment dispersion signs. The pigment dispersion syndrome may be quiescent at the time of pseudoexfoliation onset and may have gone undiagnosed. This form of glaucoma poses challenges in controlling intraocular pressure and may progress rapidly, often requiring surgical intervention. This paper reviews the common examination findings of pigment dispersion syndrome and pseudoexfoliation, which may aid clinicians in the diagnosis of the rare condition, overlap syndrome. The connection between the two conditions remains unclear, though studies of possible genetic associations are underway. The two-hit theory, or initial damage to the trabecular meshwork increasing susceptibility to future damage, is plausible given the severe nature of the condition. Though definitive conclusions regarding treatment strategies and outcomes of overlap syndrome are lacking, increased awareness, diagnosis, and study of the condition may help guide the management of overlap syndrome.

Development of protein hydrolysate as a cost-effective and robust biodispersant: Investigating its performance in dispersing of carbon black pigment in water-based paints

Carbon black pigments hold significant importance as the primary representatives of black pigments in the industry today. The dispersibility of carbon black pigment (CB) in water is limited by the nonpolar and weakly hydrophilic characteristics of the pigment's surface. Therefore, there is a critical need to devise an economical and eco-friendly approach for creating a well-dispersed and stable suspension of carbon black in an aqueous medium. The primary focus of this study was to investigate the dispersion capabilities of protein hydrolysate (HP) derived from sheep wool on CB particles in a water-based pigment concentrate. The hydrolysis degree of protein source was determined by high-performance liquid chromatography and gel permeation chromatography. The dispersion performance was investigated by zeta potential, transmission electron microscopy, Fourier transform infrared spectroscopy, grindometer, spectrophotometer-colorimeter, viscometer, and cryptometer measurements. The HP solution containing amino acids, peptides, and polypeptides with low molecular weight can cover the surface of the CB particles, creating enough electrical repulsion and steric resistance. As a result, this phenomenon can inhibit the collision and interaction among the pigment particles caused by Brownian motion, making it less prone to aggregation. The protein hydrolysate demonstrated a higher capability in producing the stable CB dispersions compared to a commercial reference dispersant, highlighting the effectiveness of amino acids, peptides, and polypeptides as powerful CB dispersing agents.

Synthesis of basic amino acid-grafted lignin for use as a high-performance pigment dispersant

Lignin is a promising dispersant due to its hyperbranched polymer structure, low cost, renewability and abundant availability. However, its use is limited by its broad molecular weight distribution, inhomogeneity, and low content of hydrophilic functional groups. In this work, lignin was functionalized with alkaline amino acids (EHL-AA) to enhance water solubility and molecular weight uniformity. The results showed that EHL-AA significantly improved the dispersion of pigment Red 57:1 (P.R.57:1) in aqueous solutions, reducing the required dosage by 50 % compared to commercial small-molecule dispersants. Additionally, histidine modified lignin (EHL-His) exhibited superior stability for P.R.57:1 compared to commercial lignosulfonate (REAX 85A). Molecular dynamics simulations further revealed that showed that EHL-His had the highest electrostatic potential difference and the largest absolute value of negative ESP. The adsorption of EHL-His onto the P.R.57:1 surface followed the pseudo-second-order kinetic model and the Langmuir model, with EHL-His showing a higher Langmuir constant (b) than REAX 85A, indicating the strongest interaction with the pigment. In summary, this work advances pigment dispersion technology and promotes the high-value utilization of lignin.

Insights into phthalocyanine blue pigment dispersion: Modeling particle size distribution and grinding rate constants

The study presents an advanced mathematical model aimed at enhancing the understanding of pigment dispersion processes, with a particular focus on analyzing the dynamics of particle size distribution and determining grinding rate constants. Pigmented dispersions are crucial in various industries, including paints, coatings, and inks, where achieving optimal particle size distribution is vital for product quality. This investigates the relationship between grinding duration and pigment dispersion, aiming to establish empirical equations for the grinding rate constant as a function of particle size distribution and feed rate. Through experimental validation, the developed kinetic model provides insights into the dynamics of pigment dispersion and offers predictive capabilities for optimizing dispersion processes. Understanding the underlying mechanisms of pigment dispersion through mathematical modeling contributes to enhancing the performance and quality of final products in diverse industrial applications. The development of a new kinetic model, effective mathematical model is proposed to accurately simulate the evolution was applicable for the particle size from 32.67 to 122.4 nm distribution of pigment during comminution processes. In addition, it was observed that the kinetic model was not applicable for the particle size from 166.2 to 190.1 nm and also confirmed that the grinding was completed within 40 min, which was possible for uniform particle size distribution.

Phakic intraocular lens exchange due to severe uveitis/inflammation: case report

Introduction: Phakic intraocular lenses (IOLs) provide excellent visual and refractive outcomes with a high safety profile. This report illustrates a case of a rare episode of severe anterior segment inflammation after iris-claw foldable lens implantation, which required surgical reintervention. Patient and Clinical Findings: A 22-year-old woman was submitted to Artiflex implantation for the correction of myopia. Three months postoperatively, a severe anterior segment inflammation developed with pigment deposition, pupillary membrane formation, and decreased visual acuity in the left eye. Diagnosis, Intervention, and Outcomes: Given the nonresponse to medical treatment (topical and systemic corticosteroid for 3 months), surgical explantation of the IOL with peeling of a pigmentary membrane over the crystalline lens was performed. During a 24-month follow-up period, the patient was monitored to exclude the development of cataract or glaucoma. Afterward, an implantable collamer lens was implanted with an uneventful intraoperative and postoperative period. During the long-term follow-up, no further pigment dispersion, uveitis, or cataract was described. Conclusions: Persistent anterior uveitis with pigmentary membrane formation after iris-claw lens implantation is a rare complication. IOL explantation needs to be considered to prevent further sequelae after severe uveitis when the situation is unresponsive to medical treatment.

Mechanochemical preparation and performance regulation mechanism of highly durable and multifunctional iron red nanocomposite pigments derived from natural mixed-dimensional palygorskite clay

Iron oxide red pigments are one of the most widely used inorganic red pigments around the world. It is always pursed to improve their physicochemical properties. Herein, a continuous mechanochemical method was employed to fabricate high-performance iron red nanocomposite pigments via anchoring α-Fe2O3 nanoparticles on the surface of natural mixed-dimensional palygorskite clay (MDPal). The mechanical force of twin-screw extrusion promoted the Si-OH groups of MDPal to coordinate with Fe3+ to form the precursor, while MDPal was activated with the residual H+ of the involved nitrate to accelerate the thermal diffusion of Al3+ into α-Fe2O3 crystal lattice, thus the nanocomposite pigments presented a bright yellowish-red color (L∗ ​= ​35.61, a∗ ​= ​33.10, b∗ ​= ​35.86, C∗ ​= ​48.80). Furthermore, the mixed-dimensional nanostructure of MDPal served as a good substrate for chemical bonding of α-Fe2O3 nanoparticles to improve the dispersion and environmental stability of iron red pigments. Due to the synergistic effect of each component and the excellent thermal and chemical stability, the obtained nanocomposite pigments exhibited excellent application prospect as functional inorganic pigments for anti-corrosion coating, overglaze ceramic and coloring and reinforcing of polypropylene, respectively. It provided a facile strategy for preparation of high-performance multifunctional iron red pigments based on MDPal.

METTL23 Variants and Patients With Normal-Tension Glaucoma

This research confirms and further establishes that pathogenic variants in a fourth gene, METTL23, are associated with autosomal dominant normal-tension glaucoma (NTG). To determine the frequency of glaucoma-causing pathogenic variants in the METTL23 gene in a cohort of patients with NTG from Iowa. This case-control study took place at a single tertiary care center in Iowa from January 1997 to January 2024, with analysis occurring between January 2023 and January 2024. Two groups of participants were enrolled from the University of Iowa clinics: 331 patients with NTG and 362 control individuals without glaucoma. Patients with a history of trauma; steroid use; stigmata of pigment dispersion syndrome; exfoliation syndrome; or pathogenic variants in MYOC, TBK1, or OPTN were also excluded. Detection of an enrichment of METTL23 pathogenic variants in individuals with NTG compared with control individuals without glaucoma. The study included 331 patients with NTG (mean [SD] age, 68.0 [11.7] years; 228 [68.9%] female and 103 [31.1%] male) and 362 control individuals without glaucoma (mean [SD] age, 64.5 [12.6] years; 207 [57.2%] female and 155 [42.8%] male). There were 5 detected instances of 4 unique METTL23 pathogenic variants in patients with NTG. Three METTL23 variants-p.Ala7Val, p.Pro22Arg, and p.Arg63Trp-were judged to be likely pathogenic and were detected in 3 patients (0.91%) with NTG. However, when all detected variants were evaluated with either mutation burden analysis or logistic regression, their frequency was not statistically higher in individuals with NTG than in control individuals without glaucoma (1.5% vs 2.5%; P = .27). This investigation provides evidence that pathogenic variants in METTL23 are associated with NTG. Within an NTG cohort at a tertiary care center, pathogenic variants were associated with approximately 1% of NTG cases, a frequency similar to that of other known normal-tension glaucoma genes, including optineurin (OPTN), TANK-binding kinase 1 (TBK1), and myocilin (MYOC). The findings suggest that METTL23 pathogenic variants are likely involved in a biologic pathway that is associated with glaucoma that occurs at lower intraocular pressures.

Bio‐based polyethylene masterbatch preparation and investigation of the effect of process conditions on pigment dispersion

AbstractAlthough the importance of bio‐polyethylene is increasing, academic research on the subject is still limited. The dispersion level of pigments and functional additives plays a crucial role in achieving the desired effect from polymer composites. This study investigates the effects of additives and process conditions on pigment dispersion in bio‐polyethylene masterbatches using four different factors and three different parameters by the Taguchi method. To achieve this, the relative colour strengths of extruder‐produced masterbatches were measured using a spectrophotometer, blown film samples were visually observed and filter pressure values were examined in a filter tester. The results were subjected to Taguchi analysis to determine which factors and parameters are important to the process and which can be neglected. The study identified the physical properties of the wax, extruder screw speed, barrel temperature and mixer time as the most effective factors on pigment dispersion, respectively. Micronised wax was found to be the most critical parameter among wax types, while mixer mixing time was found to be the least important. It was observed in all the experiments that the colour strength obtained from a constant pigment content in the masterbatches was improved by increasing the dispersion and reducing the number of agglomerated particles.

Formulation and analysis of acrylic emulsion coatings with chrome yellow, phthalocyanine blue, and red oxide pigments using high speed disperser and bead mill techniques

A major commercial problem is achieving stable and fine particle pigment dispersion, especially for aqueous pigment dispersions. It is essential to optimize dispersants in order to moisten, disperse, and stabilize pigments throughout the milling process. This study focuses on formulating acrylic emulsion coatings using chrome yellow, phthalocyanine blue, and red oxide pigment concentrates. The formulations were developed using both high-speed dispersers (HSD) and bead mills. A quality evaluation of the products from the two milling techniques was carried out. Formulations made with chrome yellow, phthalocyanine blue, and red oxide pigment concentrates in a water-based, binder-free system using bead mills, Tween-80, SLS, and cocosulphosuccinate surfactants showed narrower particle size distributions and stronger color than those made with HSD. Specifically, formulations prepared with bead mills and the aforementioned surfactants demonstrated superior color strength compared to those prepared with HSD. The color shade of acrylic emulsion coatings formulated with phthalocyanine blue and red oxide pigment concentrates, along with Tween-80 and cocosulphosuccinate surfactants using HSD, matched the standard color shade formulations prepared in bead mills. However, formulations using phthalocyanine blue pigment concentrates with SLS and oleylsulphosuccinate surfactants in HSD did not match the standard color shade prepared in bead mills.

Capsular Waves: A Warning Indicator for Potentially Malpositioned Intraocular Lenses.

To share examination findings of the lens capsule which may act as an indicator for malpositioned intraocular lenses (IOL). Single large multi-specialty private practice, Houston, Texas, USA. Focused, observational case series. A review of pre-operative images of malpositioned single-piece IOLs with at least one haptic in the ciliary sulcus was conducted. The review included five cases who were referred to a single large multi-specialty private practice from June 2023 to December 2024 for an evaluation of posterior capsular opacification (PCO) and potential Nd:YAG capsulotomy. A total of five eyes which previously had undergone cataract surgery and were referred for Nd:YAG capsulotomy for PCO were identified on slit lamp examination to have capsular waves, defined as a centripetal and circumferential striated pattern of PCO that results from a fused anterior and posterior capsule with at least part of the IOL anterior to the capsule. While one eye exhibited transillumination defects and pigment dispersion, the remainder of eyes did not. In some cases, the capsular wave was the only clue to IOL malpositioning due to a small pupil. These eyes had single-piece IOLs with at least one haptic in the sulcus and required subsequent IOL repositioning or exchange. If capsular waves are seen on slit lamp exam, a thorough inspection of IOL placement should be conducted, especially before treatment with Nd:YAG capsulotomy. Capsular waves result from anterior and posterior capsule contact with an anteriorly situated IOL. This finding is a potential indicator of at least part of an IOL positioned anterior to the anterior capsule.

Design of dark-colored acrylic coatings for increased LiDAR detection in autonomous vehicles

Light Detection and Ranging (LiDAR) is the major sensor for autonomous vehicles. It emits near-infrared (NIR) pulsed light at 905 nm and detects the reflected portion of this light from the surrounding objects. Location and surface determination of the surrounding objects is performed using the time-of-flight (the elapsed time from launch of a pulsed beam to detection of the reflected returned beam). Solvent borne acrylic paints gained wide currency for the exterior automotive coatings over the years and topcoats with conventional dark-colored pigment dispersions exhibit low reflectivity in the NIR region. The formulation of innovative topcoats with high reflectivity in this region is an urgent task for leading paint manufacturers. In this study, pigment dispersions to be incorporated in LiDAR-detectable solvent borne acrylic automotive topcoats were designed considering the surface charges of individual pigment particles for dispersant selection. Stability of designed dispersions was demonstrated and color matching studies were realized. Three dark colors encoded RAL 9011 (Graphite black), RAL 5017 (Traffic blue), and RAL 5015 (Sky blue) from the RAL 841-GL color chart were formulated as acrylic topcoats with NIR reflective pigments. Based on the surface properties of the dry films, such as gloss, haze and distinctness of image, a significant increase in LiDAR detection was achieved for each color. The results affirmed the potential use of the developed formulations as end-product paints for coating the exterior surfaces of autonomous vehicles.

Pigment Dispersion Contributes to Ocular Immune Privilege in a DBA/2J Mouse Model of Pigmentary Glaucoma.

To investigate the effects of anterior chamber pigment dispersion on ocular immune privilege and the possible mechanisms involved in a DBA/2J mouse model of pigmentary glaucoma. DBA/2J mice were utilized as a pigment dispersion model, and age-matched C57BL/6J mice were used as the control group in this study. Proteins in the aqueous humor (AH) and serum were quantified using the bicinchoninic acid assay. Immune cells in the AH were detected using hematoxylin and eosin staining and immunocytochemistry. The expression of TGF-β2 in the AH and cytokine levels (IL-10, IFN-γ) in serum were measured using ELISA. Anterior chamber-associated immune deviation (ACAID) was induced in DBA/2J mice by injecting antigens into the anterior chamber. Delayed-type hypersensitivity (DTH) assays were used to assess the induction of ACAID. In DBA/2J mice, before and after pigment dispersion, following anterior chamber injection of pigment particles, and after ACAID modeling, the expression of regulatory T cells (Tregs) was detected using flow cytometry. Compared to C57BL/6J mice, the protein concentration, immune cell count, and TGF-β2 levels in the AH were elevated in DBA/2J mice. Protein concentration and IL-10 levels in serum were increased, while IFN-γ levels were decreased in DBA/2J. Additionally, the expression of Treg cells in the spleen of DBA/2J mice was significantly increased after pigment dispersion and anterior chamber injection of pigment particles. At 3 and 6 months, DTH responses in DBA/2J mice were not inhibited, thus preventing ACAID induction. However, the opposite was observed at 9 months in DBA/2J mice. Furthermore, the ACAID group exhibited an augmented expression of Treg cells. Dispersion of pigment particles in the anterior chamber of the eye enhances the state of ocular immune privilege by influencing the immunosuppressive microenvironment and inducing more Treg cells to reestablish ACAID.

The Pigment World: Life's Origins as Photon-Dissipating Pigments.

Many of the fundamental molecules of life share extraordinary pigment-like optical properties in the long-wavelength UV-C spectral region. These include strong photon absorption and rapid (sub-pico-second) dissipation of the induced electronic excitation energy into heat through peaked conical intersections. These properties have been attributed to a "natural selection" of molecules resistant to the dangerous UV-C light incident on Earth's surface during the Archean. In contrast, the "thermodynamic dissipation theory for the origin of life" argues that, far from being detrimental, UV-C light was, in fact, the thermodynamic potential driving the dissipative structuring of life at its origin. The optical properties were thus the thermodynamic "design goals" of microscopic dissipative structuring of organic UV-C pigments, today known as the "fundamental molecules of life", from common precursors under this light. This "UV-C Pigment World" evolved towards greater solar photon dissipation through more complex dissipative structuring pathways, eventually producing visible pigments to dissipate less energetic, but higher intensity, visible photons up to wavelengths of the "red edge". The propagation and dispersal of organic pigments, catalyzed by animals, and their coupling with abiotic dissipative processes, such as the water cycle, culminated in the apex photon dissipative structure, today's biosphere.

Moxifloxacin-associated acute pigment dispersion and iris transillumination after phakic lens surgery

Introduction: Acute pigment dispersion and elevated intraocular pressure (IOP) were found after phakic intraocular lens surgery where 0.5% moxifloxacin was used. While scattered reports can be found in the literature, to the authors' knowledge, this is the first time it has been linked to intracameral 0.5% moxifloxacin. Patient and Clinical Findings: A 23-year-old man experienced symptoms of unilateral eye pain, increased IOP, diffuse pigment dispersion, transillumination defects, and mydriasis after successful bilateral Starr Visian EVO implantable collamer lens implantation. Diagnosis, Intervention and Outcomes: Intracameral moxifloxacin (0.5%) was given at the time of the procedure and was suspected to be the cause of this patient's postoperative findings. These findings are consistent with iris toxicity associated with systemic moxifloxacin. Supportive care was given, however, the resulting pigment dispersion and mydriasis are permanent. Conclusions: Although generally safe for intracameral use, moxifloxacin has the potential to be toxic to the iris. Patients with phakia may be at higher risk of this toxicity, and lower concentrations of intracameral moxifloxacin should be considered in these patients.

Zentmayer line in pigment dispersion syndrome

Zentmayer line in pigment dispersion syndrome

Pigmentary glaucoma – a case report

Pigmentary glaucoma is a type of secondary open-angle glaucoma. Mainly it is a consequence of pigment dispersion syndrome, which is characterized by pigment accumulation in the anterior segment of the eye. Pigment in the trabecular meshwork can cause increased intraocular pressure leading to glaucomatous damage of the optic nerve. We present a case of 40-year-old myopic male with typical symptoms of pigmentary dispersion syndrome who received late diagnosis of the disease. The correct diagnosis of pigmentary dispersion syndrome is crucial in preventing glaucomatous vision impairment.

Symptomatic pigment dispersion with intraocular pressure elevation attributed to intracameral moxifloxacin after open-globe injury

Background: Intracameral moxifloxacin is commonly used following intraocular surgery to prevent endophthalmitis. Pigment dispersion is a rare complication of moxifloxacin use that has mainly been reported following systemic administration. Case presentation: We report a case of unilateral pigment dispersion three weeks after open-globe repair with intracameral moxifloxacin presenting with pain, redness, photophobia, elevated intraocular pressure, marked pigment liberation, new iris transillumination defects and pigment deposits on the anterior iris surface. Conclusion: Symptomatic unilateral pigment dispersion with IOP elevation following intracameral moxifloxacin is a rare entity, but it is a crucial complication for clinicians to be aware of as intracameral antibiotic use following intraocular surgery becomes more frequent.

Efficient removal of nanoplastics from industrial wastewater through synergetic electrophoretic deposition and particle-stabilized foam formation

Microplastic particles have been discovered in virtually all ecosystems worldwide, yet they may only represent the surface of a much larger issue. Nanoplastics, with dimensions well below 1 µm, pose an even greater environmental concern. Due to their size, they can infiltrate and disrupt individual cells within organisms, potentially exacerbating ecological impacts. Moreover, their minute dimensions present several hurdles for removal, setting them apart from microplastics. Here, we describe a process to remove colloidally stable nanoplastics from wastewater, which synergistically combines electrophoretic deposition and the formation of particle-stabilized foam. This approach capitalizes on localized changes in particle hydrophilicity induced by pH fluctuations resulting from water electrolysis at the electrode surface. By leveraging these pH shifts to enhance particle attachment to nascent bubbles proximal to the electrode, separation of colloidal particles from aqueous dispersions is achieved. Using poly(methyl methacrylate) (PMMA) colloidal particles as a model, we gain insights into the separation mechanisms, which are subsequently applied to alternative model systems with varying surface properties and materials, as well as to real-world industrial wastewaters from dispersion paints and PMMA fabrication processes. Our investigations demonstrate removal efficiencies surpassing 90%.

Harnessing Standing Sound Waves to Treat Intraocular Blood Cell Accumulation.

Certain ocular conditions result from the non-physiological presence of intraocular particles, leading to visual impairment and potential long-term damage. This happens when the normally clear aqueous humor becomes less transparent, thus blocking the visual axis and by intraocular pressure elevation due to blockage of the trabecular meshwork, as seen in secondary open-angle glaucoma (SOAG). Some of these "particle-related pathologies" acquire ocular conditions like pigment dispersion syndrome, pseodoexfoliation and uveitis. Others are trauma-related, such as blood cell accumulation in hyphema. While medical and surgical treatments exist for SOAG, there is a notable absence of effective preventive measures. Consequently, the prevailing clinical approach predominantly adopts a "wait and see" strategy, wherein the focus lies on managing secondary complications and offers no treatment options for particulate matter disposal. We developed a new technique utilizing standing acoustic waves to trap and direct intraocular particles. By employing acoustic trapping at nodal regions and controlled movement of the acoustic transducer, we successfully directed these particles to specific locations within the angle. Here, we demonstrate control and movement of polystyrene (PS) particles to specific locations within an in vitro eye model, as well as blood cells in porcine eyes (ex vivo). The removal of particles from certain areas can facilitate the outflow of aqueous humor (AH) and help maintain optimal intraocular pressure (IOP) levels, resulting in a non-invasive tool for preventing secondary glaucoma. Furthermore, by controlling the location of trapped particles we can hasten the clearance of the AH and improve visual acuity and quality more effectively. This study represents a significant step towards the practical application of our technique in clinical use.

Development of near-infrared reflective inorganic pigment dispersions in the continuous phase of solvent-binder medium

Development of near-infrared reflective inorganic pigment dispersions in the continuous phase of solvent-binder medium