Assessment of conjunctival autograft reperfusion after pterygium surgery by optical coherence tomography angiography (OCT-A).

PURPOSE: To investigate the healing process of conjunctival autografts (CAG) following pterygium surgery using optical coherence tomography angiography (OCTA). METHODS: Twenty-one eyes of 21 patients diagnosed with pterygium underwent pterygium excision with CAG without using Mitomycin-C. Over a 12-week follow-up period, changes in vascular density (VD), vascular density index (VDI), and vascular length density (VLD) were assessed at two distinct depths: superficial (<200 µm) and deep (>200 µm) using OCTA. Additionally, the revascularization rate and pattern were evaluated. RESULTS: During the first week, the CAG was edematous and no sign of neovascularization was observed. In 4th week edema decreased and early signs of vascular formation appeared. In the 12th week, the deep vasculature demonstrated a greater density of interconnectivity compared to the superficial layers. VD and VLD significantly increased during the follow-up period (P < 0.05). The CAG blood flow signals exhibited a chaotic pattern, deviating from the expected centrifugal vascular pattern in the surrounding normal conjunctiva. CONCLUSION: OCTA imaging emerges as a reliable tool for the assessment of CAG vascularization, improving the monitoring of the healing process in the postoperative period. The evaluation of CAG revascularization patterns appears to be promising biomarkers that can predict the potential future recurrence.

Novel hybrid neuro-fuzzy model to anticipate the heat transfer in a heat exchanger equipped with a new type of self-rotating tube insert.

In this investigation, a combination of the wingsuit flying search (WFS) and teaching-learning-based optimization (TLBO) algorithms is developed as a new combinatorial optimization algorithm. The proposed combinatorial algorithm is tested over some well-known benchmark functions and then integrated with the artificial neural network (ANN) to construct a novel hybrid model. After that, the obtained hybrid model is employed to anticipate the experimentally obtained values of the average Nusselt number (Nu), average friction coefficient (f) as well as thermal-hydraulic performance ratio (η), in a heat exchanger equipped with a new type of self-rotating tube insert, against governing parameters. The insert is placed in the tube side of the water heater to heat natural gas. The proposed insert consists of various numbers of self-rotating modules. Indeed, the rotating insert is introduced to create effective secondary sweeping flow on the inner side of the tube. Since this type of tube insert simultaneously provides heat transfer enhancement and undesired pressure drop, a thermal-hydraulic performance ratio is defined to consider both of them. The governing parameters are the number of inserts (0 ≤ N ≤ 30), reservoir's temperature (40 °C  ≤  TR ≤ 50 °C) as well as Reynolds number (6 × 103 ≤ Re ≤ 18 × 103). It was found that the WFS-TLBO enhances the effectiveness of the main ANN in anticipating the Nusselt number (Nu), average friction coefficient (f) as well as performance ratio (η). Moreover, introducing the WFS-TLBO algorithm into the neural network provides an enhancement in the effectiveness of the hybrid models based on the single WFS and TLBO algorithms in anticipating the same parameters.

Preparation of a reproducible long-acting formulation of risperidone-loaded PLGA microspheres using microfluidic method.

The aim of the present study is to prepare risperidone-loaded poly lactic-co-glycolic acid (PLGA) microspheres within microfluidic system and to achieve a formulation with uniform size and monotonic and reproducible release profile. In comparison to batch method, T-junction and serpentine chips were utilized and optimizing study was carried out at different processing parameters (e.g. PLGA and surfactant concentration and flow rates ratio of outer to inner phase). The computational fluid dynamic (CFD) modeling was performed, and loading and release study were carried out. CFD simulation indicates that increasing the flow rate of aqueous phase cause to decrease the droplet size, while the change in size of microspheres did not follow a specific pattern in the experimental results. The most uniform microspheres and narrowest standard deviation (66.79 µm ± 3.32) were achieved using T-junction chip, 1% polyvinylalcohol, 1% PLGA and flow rates ratio of 20. The microfluidic-assisted microspheres were more uniform with narrower size distribution. The release of risperidone from microspheres produced by the microfluidic method was more reproducible and closer to zero-order kinetic model. The release profile of formulation with 2:1 drug-to-polymer ratio was the most favorable release, in which 41.85% release could be achieved during 24 days.

Nanoencapsulated Thymus daenensis and Mentha piperita essential oil for bacterial and biofilm eradication using microfluidic technology.

The use of essential oil (EO) nanoemulsions is expanding to meet customer demand for all-natural antibacterial agents. Thymus daenensis (T) and Mentha piperita (M) EOs were employed to make nanoemulsions (TEO and MEO NE), using Tween 80/Span 80 as surfactant/cosurfactant and a high-speed homogenizer. The TEO and MEO NEs were then characterized in terms of particle size (121, 113 nm), surface charge (-11.2 and -12.6 mV), morphology, and stability over time. Then, the antibacterial activity of EOs and their nanoformulations against Escherichia coli (E. coli) were evaluated based on various residence times, and concentrations on a microfluidic chip. The release of cytoplasmic constituents was used to compare the antibacterial activity of bulk EOs and nanoformulations. After completing MIC, MBC, and time-killing assays, the inhibitory effect of nanoformulations on E. coli biofilm formation was examined. Remarkable intensification was observed by employing a microfluidic chip owing to high-contact surface area provision between nanoemulsions and bacteria. Once compared to the conventional method for 3 h operation, the bacterial activity was nearly completely inhibited in a 24-min residence time using nanoemulsions. After 6 min of treatment, the cell membrane began to rupture, indicating that nanoemulsions could improve the antibacterial activity of bulk essential oils.

Berberine-loaded nanoemulsions as a natural food preservative; the impact of femtosecond laser irradiation on the antibacterial activity.

There is a growing concern among food safety regulators, the food industry, and consumers about foodborne illnesses. To improve food safety and increase shelf life, it is necessary to use natural preservatives. Natural antimicrobials are safer than artificial preservatives because they can prevent microbial resistance while also meeting consumers' demands for healthier food. This study used Berberine to enhance the antibacterial activity of Satureja Khuzistanica essential oil nanoemulsions (SKEO NE) against Staphylococcus aureus (S. aureus) bacteria, making them a promising option as preservatives. Response Surface Methodology (RSM) was employed to determine the optimized Berberine loaded SKEO NE (Berberine/SKEO NE), resulting in a mean droplet size of 88.60 nm at 6.91, 3.21, and 0.08% w/w of surfactant, essential oil, and Berberine, respectively. Berberine utilization in SKEO NE has led to an increase in antibacterial activity. The nanoemulsion samples significantly ruptured the S. aureus bacterial cell membrane, rapidly discharging cell contents. The use of a microfluidic system in tandem based on the conventional approach significantly accelerated this process. Enhancing the interaction between nanodroplets and the bacterial membrane can be achieved through the nanoemulsification process of EOs, which involves modifying their surface characteristics. This enhancement is particularly pronounced when employing microfluidic systems due to their substantial contact surface area. We investigated the potential of using femtosecond laser irradiation at a wavelength of 1040 nm to augment the antibacterial action of nanoemulsions. The combined treatment of laser and nanoemulsions significantly increased the antibacterial effect of nanoemulsions by approximately 15% for each bacterium, suggesting the potential utility of this treatment to bolster the antibacterial activity of nanoemulsions. Bacteria were trapped using optical tweezers for up to 20 min, with bacterial destruction observed starting at 3 min and exhaustive destruction evident after 20 min.

Modelling and optimization of fenton process for decolorization of azo dye (DR16) at microreactor using artificial neural network and genetic algorithm.

The Fenton process is widely employed for decolorizing industrial wastewater. Therefore, it is imperative to construct a model for optimizing the operational parameters and estimating the efficiency of decolorization within this process. In this study, an artificial neural network (ANN) model was created based on experimental data provided by a previous researcher who examined the decolorization of Direct Red 16 dye (DR16) using a heterogeneous Fenton process within a microchannel reactor. This model was utilized to optimize and forecast the efficiency of decolorization in the Fenton process. The accuracy of the model was validated by comparing its outcomes with actual experimental data. To further improve the efficiency of decolorization, optimal operational parameters were ascertained utilizing the genetic algorithm method. The study revealed that as dye concentrations increased from 10 to 40 mg/l, decolorization efficiencies improved proportionately, peaking at 89.78 %. Optimal operational parameters for maximizing efficiency were identified as a feed flow rate of 1 ml/min, H2O2 concentration at 500 mg/l, Fe2+ concentration of 4 mg/l, and maintaining pH between 2.6 and 2.8. Insights derived from both experimental and model-generated data were used to analyze the impact of operational parameters on decolorization efficiency.

Effect of orbital decompression surgery on the choroidal profile in patients with thyroid eye disease.

This study aimed to investigate the effect of orbital wall decompression surgery and reduction of proptosis on the choroidal vascularity index (CVI) and subfoveal choroidal thickness (SFCT) in patients with thyroid eye disease (TED). Fifty-one eyes from 38 patients with controlled TED and proptosis were enrolled in this study. The majority of the patients (50.9%) had a clinical activity score (CAS) of zero, and none had a CAS greater than 2. The patients underwent a complete baseline ophthalmologic examination, and their choroidal profile alterations were monitored using enhanced depth imaging optical coherence tomography (EDI-OCT) before and during the three months after surgery. Changes in SFCT, luminance area (LA), total choroidal area (TCA), and the choroidal vascularity index (CVI) were measured as the ratio of LA to TCA in EDI-OCT images. The participants had an average age of 46.47 years, and 22 were female (57.9%). The SFCT of the patients exhibited a significant reduction over the follow-up period, decreasing from 388 ± 103 to 355 ± 95 µm in the first month (p < 0.001) and further decreasing to 342 ± 109 µm by the third month compared to baseline (p < 0.001). The CVI exhibited a drop from 0.685 ± 0.037 at baseline to 0.682 ± 0.035 and 0.675 ± 0.030 at 1 and 3 months post-surgery, respectively. However, these changes were not statistically significant, indicating comparable decreases in both LA and TCA. There was a significant correlation between improved proptosis and reduction in SFCT (p < 0.001) but not with CVI (p = 0.171). In conclusion, during the three months of follow-up following orbital wall decompression, CVI did not change, while SFCT reduced significantly. Additionally, SFCT was significantly correlated with proptosis reduction, whereas CVI was not.

Analyzing Burner Performance and Combustion Phenomenon in an Olefin Plant's Industrial Furnace: A CFD Study.

This work presents a comprehensive study of the combustion performance of an industrial furnace in an olefin plant using computational fluid dynamics (CFD) simulations. The focus was on analyzing the heat release pattern of bottom burners to optimize the furnace efficiency in steam-cracking processes. The study developed an accurate computational fluid dynamics (CFD) model for predicting combustion behavior in a cracking furnace. The computational model was validated by comparing the simulation results with industrial data and was used to investigate the impact of burner clogging and the importance of small holes in the body of burners in the furnace. The results also provided insights into the influence of excess air, temperature distribution, fluid behavior, composition of combustion products, and thermal efficiency of the furnace. The presented results contributed to a better understanding of parameters controlling combustion performance in steam-cracking furnaces.

Assessment of area and structural irregularity of retinal layers in diabetic retinopathy using machine learning and image processing techniques.

Diabetes retinopathy prevention necessitates early detection, monitoring, and treatment. Non-invasive optical coherence tomography (OCT) shows structural changes in the retinal layer. OCT image evaluation necessitates retinal layer segmentation. The ability of our automated retinal layer segmentation to distinguish between normal, non-proliferative (NPDR), and proliferative diabetic retinopathy (PDR) was investigated in this study using quantifiable biomarkers such as retina layer smoothness index (SI) and area (S) in horizontal and vertical OCT images for each zone (fovea, superior, inferior, nasal, and temporal). This research includes 84 eyes from 57 individuals. The study shows a significant difference in the Area (S) of inner nuclear layer (INL) and outer nuclear layer (ONL) in the horizontal foveal zone across the three groups (p < 0.001). In the horizontal scan, there is a significant difference in the smoothness index (SI) of the inner plexiform layer (IPL) and the upper border of the outer plexiform layer (OPL) among three groups (p < 0.05). There is also a significant difference in the area (S) of the OPL in the foveal zone among the three groups (p = 0.003). The area (S) of the INL in the foveal region of horizontal slabs performed best for distinguishing diabetic patients (NPDR and PDR) from normal individuals, with an accuracy of 87.6%. The smoothness index (SI) of IPL in the nasal zone of horizontal foveal slabs was the most accurate at 97.2% in distinguishing PDR from NPDR. The smoothness index of the top border of the OPL in the nasal zone of horizontal slabs was 84.1% accurate in distinguishing NPDR from PDR. Smoothness index of IPL in the temporal zone of horizontal slabs was 89.8% accurate in identifying NPDR from PDR patients. In conclusion, optical coherence tomography can assess the smoothness index and irregularity of the inner and outer plexiform layers, particularly in the nasal and temporal regions of horizontal foveal slabs, to distinguish non-proliferative from proliferative diabetic retinopathy. The evolution of diabetic retinopathy throughout severity levels and its effects on retinal layer irregularity need more study.

Baseline optical coherence tomography angiography biomarkers predict visual outcomes in treatment-naïve neovascular age-related macular degeneration patients.

This retrospective study aimed to assess different macular neovascular network characteristics in relation to changes in best corrected visual acuity (BCVA) over 3 and 12 months following treatment. Using optical coherence tomography angiography, we reviewed the medical records of 46 treatment-naïve patients with neovascular age-related macular degeneration (nAMD) who received intravitreal aflibercept injections. The change in BCVA from baseline to 3 months and 12 months after treatment was recorded. The mean vessels percentage area, junctions density, lacunarity, and fractal dimension were significantly correlated with the change of BCVA from baseline to month 3 (P = 0.003, 0.046, 0.007, and 0.005 respectively). Fractal dimension and vessels percentage area were correlated with the change of BCVA from baseline to month 12 (P = 0.023 and 0.023 respectively). The findings suggest that baseline characteristics of macular neovascular complexes may serve as predictors for BCVA changes following treatment with aflibercept in nAMD patients.

Chitosan decorated essential oil nanoemulsions for enhanced antibacterial activity using a microfluidic device and response surface methodology.

In this work, the antibacterial activity of Satureja Khuzestanica essential oil nanoemulsions improved by employing chitosan (ch/SKEO NE) against E. coli bacterium. The optimum ch/SKEO NE with mean droplet size of 68 nm was attained at 1.97, 1.23, and 0.10%w/w of surfactant, essential oil and chitosan, using Response Surface Methodology (RSM). Applying microfluidic platform, the ch/SKEO NE resulted in improved antibacterial activity owing to the modification of surface properties. The nanoemulsion samples showed a significant rupturing effect on the E. coli bacterial cell membrane which resulted in a rapid release of cellular contents. This action was remarkably intensified by executing microfluidic chip in parallel to the conventional method. Having treated the bacteria in the microfluidic chip for 5 min with a 8 µg/mL concentration of ch/SKEO NE, the bacterial integrity disrupted quickly, and the activity was totally lost in a 10-min period at 50 µglmL, while it took 5 h for a complete inhibition in the conventional method using the same concentration of ch/SKEO NE. It can be concluded that nanoemulsification of EOs using chitosan coating can intensify the interaction of nanodroplets with the bacterial membrane, especially within the microfluidic chips which provides high contact surface area.

Delayed-Onset Endophthalmitis after Intravitreal Aflibercept Injection.

Purpose: To describe delayed-onset infectious endophthalmitis 4 months after intravitreal aflibercept injection. Methods: An 80-year-old female was referred with signs and symptoms of clinical endophthalmitis 4 months after intravitreal injection of aflibercept for choroidal neovascularization. Noninfectious causes of panuveitis were excluded and she was diagnosed with delayed-onset postinjection infectious endophthalmitis. Vitreous and aqueous specimens were prepared and antibiotics (vancomycin and ceftazidime) were injected intravitreally. Results: Vitreous culture was positive for Staphylococcus epidermidis. During the 1st month after the antibiotic injections, symptoms and signs of the patient improved and became stable during the 6-month follow-ups. Conclusions: Delayed-onset infectious endophthalmitis can be presented following intravitreal injections. Late presentation of uveitis in postinjected eyes needs complete investigations to rule out infectious endophthalmitis as an ophthalmic emergency.

Unplanned Reoperation following Vitreoretinal Surgery.

Purpose: To evaluate the incidence of unplanned return to the operating room following vitreoretinal surgery and assess the reasons. Methods: In this retrospective case series, medical records of all patients who underwent vitreoretinal surgery were reviewed to determine the incidence and reasons of early (<30 days postoperatively) and late (≥30 days postoperatively) unplanned reoperations after the surgery. Results: A total of 488 eyes of 468 patients with a mean age of 55.84 ± 18.23 years were included. Fourteen percent (68/488) of eyes required one or more unplanned reoperation following their primary surgery. These include 3.9% (19/488) for the early and 10.0% (49/488) for the late reoperation. The most common primary reason for baseline surgery was rhegmatogenous retinal detachment (RRD) without proliferative vitreoretinopathy (PVR, 38.2%), followed by RD with PVR (23.5%), and tractional RD (TRD, 19.1%). Unplanned reoperations were most common in RD with PVR (19.3%), RRD without PVR (17.2%), and TRD (14.4%). Overall, the most common reasons of the first unplanned reoperation were repeated RD with PVR (27.9%), repeated RD (19.1%), and the presence of silicone oil (SO) in the anterior chamber (AC) (10.3%). For early unplanned reoperations, SO in AC, postoperative endophthalmitis, and persistent hyphema were the most common causes. Repeated RD with PVR was the most prevalent cause of late unplanned reoperations (34.7%). In the multivariate analysis, preoperative best-corrected visual acuity (BCVA) was significantly lower in eyes with unplanned reoperation than in eyes without (P = 0.011). Conclusions: Unplanned reoperation following vitreoretinal surgery is not very common, and occurs mostly in the setting of PVR, RRD, and TRD. Lower preoperative BCVA may indicate an increased chance of future unplanned reoperation(s).

Application of ImageJ in Optical Coherence Tomography Angiography (OCT-A): A Literature Review.

Background: This study aimed to review the literature on the application of ImageJ in optical coherence tomography angiography (OCT-A) images. Methods: A general search was performed in PubMed, Google Scholar, and Scopus databases. The authors evaluated each of the selected articles in order to assess the implementation of ImageJ in OCT-A images. Results: ImageJ can aid in reducing artifacts, enhancing image quality to increase the accuracy of the process and analysis, processing and analyzing images, generating comparable parameters such as the parameters that assess perfusion of the layers (vessel density (VD), skeletonized density (SD), and vessel length density (VLD)) and the parameters that evaluate the structure of the layers (fractal dimension (FD), vessel density index (VDI), and lacunarity (LAC)), and the foveal avascular zone (FAZ) that are used widely in the retinal and choroidal studies), and establishing diagnostic criteria. It can help to save time when the dataset is huge with numerous plugins and options for image processing and analysis with reliable results. Diverse studies implemented distinct binarization and thresholding techniques, resulting in disparate outcomes and incomparable parameters. Uniformity in methodology is required to acquire comparable data from studies employing diverse processing and analysis techniques that yield varied outcomes. Conclusion: Researchers and professionals might benefit from using ImageJ because of how quickly and correctly it processes and analyzes images. It is highly adaptable and potent software, allowing users to evaluate images in a variety of ways. There exists a diverse range of methodologies for analyzing OCTA images through the utilization of ImageJ. However, it is imperative to establish a standardized strategy to ensure the reliability and consistency of the method for research purposes.

Massive Uveal Relapse of Retinoblastoma Presumed to Be Choroidal Tumorous Involvement: Case Series.

We report the choroidal and ciliary body invasion by retinoblastoma (RB) in a salvaged eye after complete and successful primary treatment. Case 1: A 25-month-old boy was referred due to group B RB lesions based on the International Classification of RB (ICRB; groups A-E) in the right eye (OD). His left eye (OS) was enucleated because of advanced group E RB. After 47 months of uneventful follow-up (F/U), a new lesion recurred and was treated with transpupillary thermotherapy. Four months later, a fast-growing pigmented subretinal mass was detected that was treated by brachytherapy with the apical dose of 80 Gy. Three weeks later, the lesion regressed completely, and no recurrence happened after 6 years of F/U. Case 2: A 4-month-old girl with a deletion in chromosome 13 was referred for bilateral RB. OD was enucleated because of unresponsive RB and anterior segment involvement. In OS, group B lesions had multiple recurrences after systemic chemotherapy. After a while, a single mass appeared in the nasal periphery which was controlled well with brachytherapy. Four months later, AC involvement was controlled with IAC, intravitreal, and intracameral chemotherapy, but posterior synechia and cataract appeared later. One year after the last treatment, UBM showed a ring-shaped ciliary body mass. Her parents refused enucleation again, and she received intravenous chemotherapy. Two years later, magnetic resonance imaging showed orbital and optic canal involvement with a deformed globe. In conclusion, RB recurrence can appear as local choroidal and ciliary body involvement even after a time of complete remission. The role of B-scan and UBM in early diagnosis and successful treatment is valuable.

Pachychoroid neovasculopathy versus macular neovascularization in age-related macular degeneration with and without shallow irregular pigment epithelial detachment.

To compare the choroidal neovascular features of individuals with pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD) with and without shallow irregular pigment epithelial detachment (SIPED). Using optical coherence tomography angiography, the choroidal neovascular complexes of 27 patients with PNV, 34 patients with nAMD and SIPED, and 15 patients with nAMD without SIPED were analyzed with FIJI and AngioTool software. PNV compared to nAMD with SIPED had a greater vessel percentage area (P = 0.034), junction density (P = 0.045), average vessel length (P < 0.001), and fractal dimension (P < 0.001). PNV, compared to nAMD without SIPED, had a greater total vessel length (P = 0.002), total number of junctions (P < 0.001), junction density (P = 0.034), and fractal dimension (P = 0.005). nAMD with SIPED, compared to nAMD without SIPED, had greater vessel area, total number of junctions, total vessel length, and average vessel length (all P values < 0.001). Patients with nAMD plus SIPED and individuals with nAMD without SIPED have similar fractal dimension values (P = 0.703). Biomarkers of choroidal neovascular complexity, such as fractal dimension, can be used to differentiate PNV from nAMD with or without SIPED.

Interaction of a natural compound nanoemulsion with Gram negative and Gram positive bacterial membrane; a mechanism based study using a microfluidic chip and DESI technique.

The antibacterial activity of a nanoemulsion prepared from Satureja Khusitanica essential oil against a Gram-negative (Escherichia coli) and a Gram-positive (Bacillus atrophaeus) bacteria evaluated using microfluidic and conventional techniques. The effect of different residence time and concentrations on the antibacterial activity of nanoemulsion was studied by measuring the release of protein, nucleic acids, potassium, and also recording the MIC, MBC and time killing assays. Remarkable intensification was observed by employing microfluidic chip regarding a high-contact surface area between nanodroplets and bacterial membrane. The MIC and MBC values for E. coli and B. atrophaeus in conventional method were 400 and 1600 µg mL-1, respectively, whereas these values reduced to 11 to 50 µg mL-1 using microfluidic system. B. atrophaeus seemed to be more resistant than E. coli to the nanoemulsion treatment, perhaps due to different cell wall structures. Bacterial cell wall changes were examined using a desorption electrospray ionization (DESI) technique. It was found that the structural changes were more imminent in Gram negative E. coli by detecting a number of released lipids including phosphatidyl glycerol and phosphatidyl ethanolamines. The DESI spectra of B. atrophaeus revealed no M/Z related lipid release. These findings may help providing novel nano based natural antibacterials.

The Impact of Mobile-Assisted Language Learning on English as a Foreign Language Learners' Vocabulary Learning Attitudes and Self-Regulatory Capacity.

Over the past decades, English as a foreign language (EFL) learning has witnessed a heightened interest in the role of mobile-assisted language learning (MALL) in vocabulary learning. To shed more light on the impact of MALL on vocabulary learning, this study, employing a quantitative longitudinal design, aimed at examining the impact of a MALL programme on 139 EFL learners' vocabulary learning attitudes and self-regulatory capacity. To this end, this study investigated the latent change score models of the learners' vocabulary learning attitudes and self-regulatory capacity over time. Over the course of 1 year, various mobile applications were integrated into the regular English language instruction of the learners. The required data were collected via administering vocabulary learning attitude and self-regulating capacity in vocabulary learning scales. The data were analysed applying latent growth curve modelling to examine the participants' longitudinal trajectories and patterns of change in the two waves of collected data. The fit indices of the latent change models revealed an increase in both the EFL learners' vocabulary learning attitudes and their self-regulatory capacity during the 1-year MALL programme. The analysis of between-person differences also indicated that changes in both variables were positively correlated.

Chitosan/tripolyphosphate nanoparticles in active and passive microchannels.

BACKGROUND AND PURPOSE: In recent years, the interest in chitosan nanoparticles has increased due to their application, especially in drug delivery. The main aim of this work was to find a suitable method for simulating pharmaceutical nanoparticles with computational fluid dynamics (CFD) modeling and use it for understanding the process of nanoparticle formation in different types of microchannels. EXPERIMENTAL APPROACH: Active and passive microchannels were compared to find the advantages and disadvantages of each system. Twenty-eight experiments were done on microchannels to quantify the effect of 4 parameters and their interactions on the size and polydispersity index (PDI) of nanoparticles. CFD was implemented by coupling reactive kinetics and the population balance method to simulate the synthesis of chitosan/tripolyphosphate nanoparticles in the microchannel. FINDINGS/RESULTS: The passive microchannel had the best performance for nanoparticle production. The most uniform microspheres and the narrowest standard deviation (124.3 nm, PDI = 0.112) were achieved using passive microchannel. Compared to the active microchannel, the size and PDI of the nanoparticles were 28.7% and 70.5% higher for active microchannels, and 55.43% and 105.3% higher for simple microchannels, respectively. Experimental results confirmed the validity of CFD modeling. The growth and nucleation rates were determined using the reaction equation of chitosan and tripolyphosphate. CONCLUSION AND IMPLICATIONS: CFD modeling by the proposed method can play an important role in the prediction of the size and PDI of chitosan/tripolyphosphate nanoparticles in the same condition and provide a new perspective for studying the production of nanoparticles by numerical methods.

A microfluidic chip for visual investigation of the interaction of nanoemulsion of Satureja Khuzistanica essential oil and a model gram-negative bacteria.

Nanotechnology has provided novel approaches against food born and pathogenic bacteria. Within the present study, the effects of pure and nanoemulsified essential oil derived from Satureja Khuzistanica essential oil (SKEO) on Escherichia coli (E. coli ATCC 25922) as a human pathogen has been studied using a microfluidic chip. The morphology and antibacterial activity of E. coli at disparate residence durations (from 2 to 30 min) and various nanoemulsified or pure essential oil concentrations (8.0-62.5 µg mL-1) and numerous nanoemulsion's droplet sizes from 32 to 124 nm, have been investigated in the microfluidic system. Also, the quantitative analysis including optical density, time killing assay, protein, nucleic acid and potassium release were employed to confirm the effects of bacterial inhibition taking advantage of the chip apparatus. It was revealed that the prepared nanoemulsion left a considerable destructive effect on E. coli bacterial membrane, confirmed by fast release of cytoplasmic elements including protein, nucleic acid and potassium. However, this process was remarkably intensified for both nanoemulsion and pure essential oil using the microfluidic chip versus the conventional methods. The results also revealed that after 4 min of bacterium treatment by 12.5 µg mL-1 nanoemulsion with 32 nm mean particle size, the bacterial membrane wall began to degrade rapidly, and bacterial activity was almost completely inhibited in a 20-min period. These findings may have implications in the similarly structured and phospholipid-encapsulated bacteria and viruses, like COVID-19.