Mean Particle Diameter Research Articles

Coupling static multiple light scattering (SMLS) analysis with the Hansen approach for the rationalization of the dispersibility and colloidal stability of TiO2 particle dispersions

While the characterization of dispersibility and colloidal stability remains a key step in many formulation processes, these notions are still confused, and colloidal stability is often interpreted as a direct consequence of dispersibility. In this study, Static Multiple Light Scattering (SMLS) measurements and the predictive Hansen approach are combined to distinguish and characterize the dispersibility and the colloidal stability of TiO2 P25 particles dispersed in pure and mixture of solvents. To this aim, an experimental protocol is proposed using fast time resolved SMLS measurements at a fixed height to assess suspension dispersibility under mechanical stirring as well as space and time resolved SMLS measurements of the suspension stability at rest. Dispersibility is quantified through a Dispersibility Index (DI) depending on the mean diameter of particles and transmission or backscattering signals standard deviation measured with SMLS under mechanical stirring. Quantification of colloidal stability is obtained from a Relative Turbiscan Stability Index (RTSI) measured at rest. Scoring of solvents is performed using the DI and the RTSI to build Hansen dispersibility and stability spheres respectively. It is found that the dispersibility and the stability spheres are clearly separated arguing that a lower colloidal stability is not necessarily a consequence of a poor dispersibility. Beyond this clarification, this combined SMLS-Hansen approach is a major step toward the optimization of dispersibility and stability of formulations. It can be also intended to find better dispersion media, greener and cheaper solvents to optimize particles suspensions, to reduce the content of costly stabilizing additive or to satisfy product regulatory requirements evolution.

Rice bran oil-in-water optimized emulsions for the development of plant-based foods and beverages

Aim: This work aimed to develop rice bran oil-in-water (O/W) emulsions, stabilized with different mixtures of pea protein concentrate (PPC), Arabic gum (AG), and maltodextrin (MD), as the basis for the formulation of plant-based food products. Methods: The effects of the aqueous phase formulation on the properties of the resulting O/W emulsions were evaluated by a mixture design approach. Volume-weighted mean diameter (D[4,3]) of the emulsion particles and polydispersity expressed as the difference of D[4,3] – D[3,2], apparent viscosity at a shear rate of 200 s–1 and backscattering at different times associated to the global stability of the emulsions were studied as response variables. A multi-response optimization was carried out and mathematical models were validated. Results: The ternary mixtures of the aqueous phase showed significant antagonism between the three components in all the response variables. The optimal formulation of the aqueous phase for the O/W emulsions obtained after three homogenization cycles was 78% PPC and 22% MD. The properties of the O/W optimal emulsion were according to the ones predicted by the model. Conclusions: The best-formulated emulsion is promising for developing plant-based foods and beverages.

Resolved CFD-DEM simulation of proppant aggregating and bridging mechanisms in a narrowing fracture

In this work, we establish a resolved coupling model that integrates computational fluid dynamics and discrete element method (i.e., resolved CFD-DEM) to numerically reproduce the proppant bridging phenomenon reported in previous experiments and further reveal the underlying mechanisms leading to proppant bridging. Out study reveals that the CFD-DEM model with the consideration of an appropriate cohesion energy density parameter (e.g., 5 × 104 N/m2 in our models) can reasonably well capture the micro-scale dynamic features of proppant aggregating and bridging occurring at the fracture tip. Moreover, our simulations indicate that the critical ratio of the fracture width to the mean particle diameter leading to proppant bridging is approximately 1.9, which agrees well with experimental results. In a closed boundary fracture model considering fluid leak-off, proppant size significantly influences aggregating locations: smaller proppants are trapped close to the fracture tip, while larger proppants are aggregated at locations close to the fracture inlet.

Gelatine nanoparticles encapsulating three edible plant extracts as potential nanonutraceutical agents against type 2 diabetes mellitus

Aim To optimise, and characterise gelatine nanoparticles (GNPs) encapsulating plant extracts and evaluate the glucose-lowering potential. Methods GNPs encapsulating plant extracts were prepared by desolvation method followed by adsorption. The GNPs were characterised by loading efficiency, loading capacity, particle size, zeta potential, SEM and FTIR. The glucose-lowering activity of GNPs was determined using oral glucose tolerance test in high-fat diet fed streptozotocin-induced Wistar rats. Results Loading efficiency and capacity, particle mean diameter, and zeta potential of optimised GNPs 72.45 ± 13.03% w/w, 53.05 ± 26.16% w/w, 517 ± 48 nm and (−)23.43 ± 9.96 mV respectively. GNPs encapsulating aqueous extracts of C. grandis, S. auriculata, and ethanol 70% v/v extracts of M. koenigii showed glucose-lowering activity by 17.62%, 11.96% and 13.73% (p < 0.05) compared to the non-encapsulated extracts. FTIR analysis confirmed the encapsulation of phytoconstituents into GNPs. SEM imaging showed spherical GNPs (174 ± 46 nm). Conclusion GNPs encapsulating plant extracts show promising potential to be developed as nanonutraceuticals against diabetes.

Mesoscale self-organization of polydisperse magnetic nanoparticles at the water surface.

In this study, we investigated the self-ordering process in Langmuir films of polydisperse iron oxide nanoparticles on a water surface, employing in situ x-ray scattering, surface pressure-area isotherm analysis, and Brewster angle microscopy. X-ray reflectometry confirmed the formation of a monolayer, while grazing incidence small-angle x-ray scattering revealed short-range lateral correlations with a characteristic length equal to the mean particle size. Remarkably, our findings indicated that at zero surface pressure, the particles organized into submicrometer clusters, merging upon compression to form a homogeneous layer. These layers were subsequently transferred to a solid substrate using the Langmuir-Schaefer technique and further characterized via scanning electron microscopy and polarized neutron reflectometry. Notably, our measurements revealed a second characteristic length in the lateral correlations, orders of magnitude longer than the mean particle diameter, with polydisperse particles forming circular clusters densely packed in a hexagonal lattice. Furthermore, our evidence suggests that the lattice constant of this mesocrystal depends on the characteristics of the particle size distribution, specifically the mean particle size and the width of the size distribution. In addition, we observed internal size separation within these clusters, where larger particles were positioned closer to the center of the cluster. Finally, polarized neutron reflectometry measurements provided valuable insights into the magnetization profile across the layer.

Computational Fluid Dynamics Numerical Simulation on Flow Behavior of Molten Slag–Metal Mixture over a Spinning Cup

Centrifugal granulation technology using a spinning cup opens a potential way to recycle steel slag that is currently difficult to reuse. The objective of this research was to study the flow characteristics of a molten slag–metal mixture that was produced during smelting reduction in molten steel slag, passing over a spinning cup, so as to explore the feasibility of using centrifugal granulation technology to treat the steel slag. This was achieved by developing and implementing a computational fluid dynamics (CFD) model that incorporated free-surface multiphase flow to predict the thickness of the liquid slag film at the edge of the spinning cup (slag film thickness for short), which was an important parameter for estimating the size of the slag particles resulting from centrifugal granulation of the molten slag–metal mixture. The influences of various relevant parameters, including spinning cup diameter, slag feeding rate, cup spinning speed, etc., on the slag film thickness were analyzed. Additionally, hot experiments on centrifugal granulation of a molten slag–metal mixture were conducted to verify the results of the numerical simulations. The experimental results indicated a progressive reduction in the Sauter mean diameter of the slag particles as the metallic iron content in the slag increased. Specifically, when the iron content rose from 5% to 15% at a cup spinning speed of 2500 RPM, the Sauter mean diameter decreased by 13.77%. The numerical simulation results showed that the slag film thickness had a positive relationship to the slag feeding rate but a negative relationship to the spinning cup diameter and the cup spinning speed. Furthermore, the ratio between the mean slag particle diameter and the slag film thickness decreased nearly linearly with the increase in the metallic iron content in slag, with the average ratio being approximately 4.25, and this relationship was useful for estimating the slag particle size from the slag film thickness. Therefore, the present research results can provide theoretical guidance for the industrial application of spinning cup centrifugal granulation technology to effectively treat and recycle steel slags.

Evaluation of a Partector Pro for atmospheric particle number size distribution and number concentration measurements at an urban background site

Abstract. Particle number size distributions, total number concentrations and mean particle sizes have been measured for 70 d at an urban background site in Mülheim-Styrum, Germany, with a handheld Partector Pro of the first generation and a TSI mobility particle size spectrometer (MPSS). The aim of the study was to evaluate the performance of the Partector Pro against the MPSS. The results show that the size distributions, measured with the Partector Pro, agree with the MPSS mostly within ± 25 % for particle sizes between 10 and 113.5 nm, whereas higher, systematic differences were observed for larger particles. The measurement accuracy was shown to be dependent on the geometric mean diameter and the geometric standard deviation of the aerosol. Best results were found for the most abundant size distributions with geometric mean particle diameters ≥ 30 nm and geometric standard deviations larger than 1.8. The total number concentration, measured by the Partector Pro, was found to be in excellent agreement with the MPSS with a slope of the linear fit of 0.9977 and a regression coefficient of R2=0.9956. The agreement of the geometric mean particle diameter, determined with the Partector Pro and the MPSS was good but moderately dependent on the particle size distribution. For mean particle sizes between 20 and 50 nm, the bias was within ±15 %. Higher deviations of up to 30 % were observed when the geometric mean particle sizes exceeded 70 nm and when the geometric standard deviations exceeded approximately 2.7.

Effect of Spray Drying on Physicochemical Stability and Antioxidant Capacity of Rosa pimpinellifolia Fruit Extract-Loaded Liposomes Conjugated with Chitosan or Whey Protein During In Vitro Digestion

Spray drying is a well-established, energy efficient, and scalable process widely used in the food industry, however it may lead to thermal degradation of susceptible compounds, such as (poly)phenols, resulting in biological activity loss to some extent. In this study, we aimed to improve the physicochemical stability and bioaccessibility of (poly)phenols from Rosa pimpinellifolia fruit extract (Rosa extract) loaded in liposomes by generating solid particles via spray drying. Liposomes were conjugated with chitosan (Ch) and whey protein (Wp) to optimize the biopolymer concentrations by monitoring mean particle diameter, polydispersity index, and surface charge. The mean diameter of liposomes ranged between 135 and 210 nm upon optimal addition of Ch (0.4%, w/v) and Wp (4.0%, w/v) which also increased the entrapment efficiency of (poly)phenols from 74.2 to 77.8% and 79.1%, respectively. After spray drying, about 65–76% of the antioxidant capacity were retained in biopolymer-conjugated liposomes (Ch or Wp) while the retention rate was 48% in only spray-dried extract (Rosa extract powder). Compared to unencapsulated Rosa extract, spray drying (Rosa extract powder) and conjugation with Ch (Ch-Lip powder) or Wp (Wp-Lip powder) significantly increased the bioaccessibility of (poly)phenols and preserved their antioxidant capacity. Based on the findings of this study, Ch- or Wp-conjugation of liposomes prior to spray drying could improve physicochemical stability and protect (poly)phenols loaded in liposomes against processing stress and passage through the digestive tract. Further in vitro and in vivo investigations on a variety of bioactive compounds may draw more attention to their potential as functional foods.

Potential of a bed ventilation system in reducing the risk of exposure to contaminants in infectious wards

A proposed bed ventilation system named Hospital Bed Integrated Ventilation Cleansing Unit (HBIVCU) has shown its great potential in reducing the risk of airborne cross-infection. However, the key operating parameters are still unclear, restricting its practical application. This study numerically investigated the performance of the HBIVCU under various operating parameters (supply and exhaust airflow rates increased from 0 L/s to 5 L/s and 0 L/s to 40 L/s, respectively) in a four-bed infectious ward with different background ventilation rates. Both tracer gas CO2, (simulating aerosols smaller than 5 μm) and particles (mean diameter of 80 μm) in the exhaled by one of the patients were considered. Compared to the ward without the HBIVCU, the concentration of CO2 at the bed microenvironment and breathing height of standing and sitting persons are reduced by more than half when the HBIVCU operates with supply and exhaust airflow rates of 5 L/s and 40 L/s, respectively. For this case, the highest draught risk of 13% at the patients’ head region is obtained. Increasing the supply and exhaust airflow rates of the HBIVCU are both helpful for removing the exhaled gaseous contaminants from the room due to increased induction effect of the local bed ventilation flow. The removal efficiency is around twice higher when the HBIVCU is operating at background ventilation at 6 air changes per hour (ACH) when compared to when it is not operating at background ventilation of 12 ACH. Finally, the HBIVCU can efficiently remove the exhaled gaseous contaminants, though it has no discernible effect on the removal of coughing droplets. The HBIVCU has great potential to reduce the risk of cross-infection and save energy by lowering the background ventilation rate.

Effects of Heat Treatment and Erosion Particle Size on Erosion Resistance of a Hypereutectic High-Chromium Cast Iron

This research addresses the erosive resistance of a hypereutectic high-chromium cast iron subjected to solid particle erosion. The study stems from a specific application of high-chromium cast iron, i.e., the critical surfaces of large industrial fans operating in a cement clinker grinding plant where such damage is a limiting factor for the components’ lifespan. A dedicated experimental investigation on the impact of substrate microstructure and erodent particle size on erosion resistance was set. The experimental campaign, conducted on a dedicated test bench per the ASTM G76 standard, comprised the analysis of the as-received, tempered, and destabilized conditions for the cast iron. From a preliminary image analysis of the microstructural features, two diameters of the erodent powder for the erosion tests were defined. The observed erosion rate decreased with the increase in the mean particle diameter of the erodent, indicating more severe erosive conditions for smaller particles. From the analysis of the worn surfaces, it was possible to highlight the involved mechanisms concerning the considered test combinations. For the as-received condition, the erosion rate with the larger mean particle diameter of the erodent decreased three times compared to the smaller one. For the heat-treated conditions, the erosion rate was halved with the larger mean particle diameter of the erodent. The proposed analysis, intended to acquire more insight into the limiting factor for the components’ lifespan for erosive wear damage, proved that erosion resistance is not dependent on the material’s hardness. The contribution of the mean particle diameter of the erodent is predominant compared to the substrate conditions.

Fabrication of Biopolymeric nanoparticles of colostrum whey-caseinate, Characterization, and In vitro digestibility

Bovine colostrum contains bioactive proteins while thermal processing reduces the functionality and gastric conditions reduce the bioactivity of these proteins. In this study, the structure of caseinate and colostrum whey was modified using ethanol to fabricate the nanoparticles (NPs). The effect of pH (4–7), whey (0.25–1.0%, w/v), and caseinate (0.5–2.0%, w/v) concentrations was also evaluated to fabricate stable NPs. The stable NPs were prepared at pH 6.5 using caseinate (1.50%, w/v) and whey (0.75%, w/v) in an aqueous medium with a mean particle diameter of <200 nm. Amide I showed changes between 1250 and 910 cm−1 in caseinate and mixture while the secondary structure (β-helix at 1636 cm−1) showed slight changes in whey and NPs and there was a decrease in the intensity of peak at 1521 cm−1 (amide II) in caseinate due to ethanol. The functional properties of NPs powder were improved as compared to whey powder and In vitro digestibility also showed improved recovery of Igs from NPs as compared to whey protein. These colostrum whey-based NPs can be used as dietary supplements to deliver bioactive proteins with numerous health advantages.

Cluster-doping in silicon nanocrystals.

Creating tin-alloyed silicon nanocrystals with tailored bandgap values is a significant challenge, primarily because a substantial concentration of tin is essential to observe useful changes in the electronic structure. However, high concentration of Sn leads to instability of the silicon-tin nanocrystals. This work introduces a completely new approach to doping and the modification of the electronic structure of nanoparticles by incorporating few-atom clusters in nanocrystals, deviating from isolated atom doping or attempting alloying. This approach is exemplified via a combined theoretical and experimental study on tin (Sn) 'cluster-doping' of silicon (Si) nanocrystals, motivated by the opportunities offered by the Si-Sn system with tailored band energy. First-principles modelling predicts two noteworthy outcomes: a considerably smaller bandgap of these nanocrystals even with a modest concentration of tin compared to an equivalent-sized pure silicon nanocrystal and an unexpected decrease in the bandgap of nanocrystals as the diameter of nanocrystals increases, contrary to the typical quantum confined behaviour. Experimental verification using atmospheric pressure microplasma synthesis confirms the stability of these nanocrystals under ambient conditions. The plasma-synthesised nanocrystals exhibited the predicted atypical size-dependent behaviour of the bandgap, which ranged from 1.6 eV for 1.4 nm mean diameter particles to 2.4 eV for 2.2 nm mean diameter particles.

Humic acid application on soil stability indices and enzyme activity at different bell pepper water requirements

Use of organic materials helps in reducing the consumption of chemical fertilizers, contributing to the sustainability of agricultural ecosystems. Humic acid can improve soil structure, especially in soils with low clay content, aiding in water retention and enhancing water absorption by plants. This characteristic has led to the attention of humic acid application in drought stress, particularly in arid soil regions. The present study aimed to investigate the simultaneous effects of humic acid and plant water requirements on the physical and biological properties of soil under bell pepper cultivation. The factorial experiment was conducted in a completely randomized block design with three levels of humic acid: 0 (HA0), 2 (HA2), and 4 (HA4) g/Kg of soil and four levels of plant water requirements: 60 (L60), 80 (L80), 100 (L100), and 120 % (L120), with four replications under greenhouse conditions. Bell pepper seedlings were transferred to 10 Kg pots after applying humic acid treatments and after the establishing of seedlings, plant water requirement treatments were applied for 80 days. During this period, plants were maintained at a temperature of 25 degrees Celsius during the day, 18 degrees Celsius at night, and a relative humidity of 75%, with a carbon dioxide concentration of 80 milligrams per liter. The results of this study showed that treatments L80HA4, L100HA4, and L120HA4 had the most significant impact on improving soil physical properties, such as normal stability index, total soil stability index, mean weight diameter of soil particles, soil particle stability, geometric mean diameter of soil particles, and reduction in soil particle destruction percentage. The highest values of wet and dry weight diameter of soil particles were observed in treatment L100HA4, which were 42.92%, 74%, and 67.01% higher, respectively, compared to the control (L60HA0). In contrast, the highest percentage of soil particle destruction was observed in treatment L60HA0, showing a 32.90% increase compared to treatment L100HA4. Furthermore, the best performance of bell pepper yield was observed in treatments L80HA4, L100H4, and L120HA4, although the differences between treatments were not statistically significant. The application of humic acid, in addition to improving bell pepper yield, increased water use efficiency and reduced water use. The lowest yield (3283 Kg/ha) and the lowest water consumption (3584 cubic meters/ha) were observed in treatments L60HA0 and L60HA4, respectively. Additionally, the results showed that the highest water use efficiency observed in L80HA4 treatment (7.45 Kg/m³), while the lowest was in L60HA0 treatment (0.80 Kg/m³). Moreover, humic acid significantly influenced the activity of soil enzymes, including soil phosphatase and urease. With more application of humic acid, soil moisture retention, microbial biomass carbon, urease, phosphatases activities increased. However, in treatments with full water requirements and 20 percent more than plant water requirements, enzyme activities decreased.

Exploratory measurements of ambient air quality in a residential area applying a diffusion charge based UFP monitor/Orientierende Messungen der Luftqualität in einem Wohngebiet mit einem auf Diffusionsaufladung basierten UFP-Monitor

In the context of the revision of the EU Ambient Air Qualitiy Directive (2008/50/EC), measurement of ultrafine particles (UFP) in ambient air is proposed and discussed. To investigate the local ambient UFP concentration (immis- sion), exploratory measurements of air pollution with UFPs were performed over several months in a residential area. The measurement device is based on charge detection of the measurement aerosol (AQ Guard Smart 2000 of the manufacturer Palas®). The background particle concentrations are within the typical background level for rural residential areas (3,000 to 5,000 cm-3). Increased UFP concentration levels were predominantly measured during the evening and the night. On 53 days of the total measurement duration of 101 days increased par- ticle concentrations above the background level (at least 6,000 cm-3) regarding the 15-minute average values were measured for at least one hour during the evening and night (16:00 to 0:00). The main source of the increased particle concentra- tion is the operation of woodstoves in the neighbourhood of the measuring location. This air pollution in the evening hours is not reflected in the context of daily or monthly averages. Other pollution sources (barbecue, new-years fireworks, traffic – different measurement location) were also identified and differences of the mean particle diameter of the ambient aerosol with regards to the background level (80 nm) could be determined. The device is suitable for UFP measurements and offers a lower detectable size-range compared to conventional scattered-light based optical particle counters.

Preparação de farinha de resíduos de tilápia do Nilo (Oreochromis niloticus) para consumo humano

ABSTRACT: This study aimed to prepare and characterize Nile tilapia (Oreochromis niloticus) waste meal. The experimental design consisted of three treatments (carcass meal, mechanically separated meat meal - MSM, and head meal) and five replications of each treatment. Yield, microbiological quality, pH, water activity, proximate composition, energy value, mineral composition, fatty acid profile, amino acid composition, color, and particle size fractions and the geometric mean particle diameter (GMD) analyses were performed. Data were subjected to ANOVA, and means were compared by Tukey’s test at P &lt; 0.05. Carcass, mechanically separated meat, and head meals had a protein content of 56.45%, 78.60%, and 50.33%, respectively, a lipid content of 7.16%, 13.15%, and 4.58%, respectively, and an ash content of 32.61%, 4.26%, and 38.41%, respectively. The mean yield of fish waste meals was 13%. Oleic, palmitic, and linoleic acids were the major fatty acids in the three fish waste meals, and glutamic acid, leucine, lysine, and glycine were the major amino acids. Color analysis showed that lightness (L*) ranged from 55.32 to 77.19, redness (a*) from 4.44 to 4.88, and yellowness (b*) from 4.13 to 9.51. The GMD ranged from 0.37 to 0.99 mm. The results indicate that Nile tilapia waste meals have high nutritional value and adequate pH, water activity, and microbiological quality for use in human nutrition.

D03-ordered Fe3Al magnetic nanopowders synthesized by low oxygen induction thermal plasma

D03-ordered Fe3Al alloy with a large anomalous Nernst coefficient is considered as a promising candidate for a low-cost, flexible, and durable magneto-thermoelectric generator (MTG). To improve the thermoelectric performance of the more and more complex and smaller MTG modules, the incorporation of high-quality magnetic nanopowders (MNPs) is one solution. However, synthesizing fully chemically ordered MNPs without coalescence and/or oxidation with a conventional approach is challenging. In this study, we demonstrated, for the first time, D03-ordered (degree of ordering = 0.48) Fe3Al MNPs synthesized via a low oxygen thermal plasma process combined with appropriate post-annealing treatment. The resulting single crystalline MNPs are spherical in shape with a mean particle diameter of 116 ± 96 nm and exhibit a soft magnetic characteristic (saturation magnetization ≈ 112 emu/g; and coercivity ≈ 5 Oe at room temperature). The fundamental alloying mechanism during the thermal plasma process was investigated via numerical calculations, confirming that the alloying followed the route through the Fe-Al droplet. Our results will potentially aid the mass synthesis of chemical ordered MNPs for wearable energy harvesting and self-powered Internet of things applications.

Carbon black production characteristics and mechanisms from pyrolysis of rubbers

Pyrolysis is a promising way to treat the waste tires for high value carbon black production. However, the carbon black formation mechanism is still unclear due to the complex decomposition and polymerization reactions during the pyrolysis of tire components. In this study, the production behavior, characters, and mechanism of carbon black from pyrolysis of natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR) were investigated. The yield of carbon black was increased from 20.8%–24.4% to 47.9%–56.7% with the increase of pyrolysis temperature from 1100 to 1300°C. Although the carbon black production yield from NR was lower than that of BR and SBR at 1300°C, the graphitization degree (ID/IG = 2.22), microcrystal length (3.17 nm) and mean particle diameter (90.3 nm) of the carbon black derived from NR were the highest. The volatile evolution, carbon black nucleation mechanisms were revealed by reactive force-field molecular dynamics simulations. The pyrolysis of BR and SBR generated more C2H2, C2H3⋅, long carbon-chains and cyclic molecules than NR, which probably resulted in a higher carbon black yield than NR. With few defect borders, regular stacking and wrapping of the aromatic layers, the carbon black from NR exhibited more ordered nucleation and high graphitization degree.

Photochromic performance optimization of polyurethane microcapsules by interfacial polymerization method

AbstractSpiropyran photochromic materials have been widely studied in military camouflage, optical data storage, information encryption, and fashion ornaments. The non‐photochromism and low endurance of solid spiropyran make the challenges of their application. Photochromic microcapsules with a butyl acetate solution of spiropyran as core and polyurethane as shell are synthesized via interfacial polymerization. The optimized polyurethane photochromic microcapsules are prepared with a Tween 20 concentration of 4 wt%, core–shell ratio of 16:5, and spiropyran concentration of 0.40 wt%. Polyurethane photochromic microcapsules with a mean particle diameter of 0.33 μm are obtained. The morphology shows smooth spheres, and the core–shell structure is observed. Butyl acetate in the microcapsule core does not evaporate at a temperature lower than 218.01°C as the microcapsule shell insulates heat. The polyurethane photochromic microcapsules are mixed with adhesive, thickener, and water into a paste and screen‐printed on cotton fabric. The printed fabric shows the ΔE of 17.56, 11.93, and 6.96 after 80s irradiation with the xenon lamp intensity of 102, 68, and 34 mW cm−2. The light stability of the photochromic fabric is excellent as ΔE decreases about 8.28% after 20 cycles of UV‐Vis irradiation.

Comparative analysis of SARS-CoV-2 variants Alpha (B.1.1.7), Gamma (P.1), Zeta (P.2) and Delta (B.1.617.2) in Vero-E6 cells: ultrastructural characterization of cytopathology and replication kinetics

This study compares the effects of virus-cell interactions among SARS-CoV-2 variants of concern (VOCs) isolated in Brazil in 2021, hypothesizing a correlation between cellular alterations and mortality and between viral load and transmissibility. For this purpose, reference isolates of Alpha, Gamma, Zeta, and Delta variants were inoculated into monolayers of Vero-E6 cells. Viral RNA was quantified in cell supernatants by RT‒PCR, and infected cells were analyzed by Transmission Electron Microscopy (TEM) for qualitative and quantitative evaluation of cellular changes 24, 48, and 72 hours postinfection (hpi). Ultrastructural analyses showed that all variants of SARS-CoV-2 altered the structure and function of mitochondria, nucleus, and rough endoplasmic reticulum of cells. Monolayers infected with the Delta variant showed the highest number of modified cells and the greatest statistically significant differences compared to those of other variants. Viral particles were observed in the cytosol and the cell membrane in 100 % of the cells at 48 hpi. Alpha showed the highest mean particle diameter (79 nm), and Gamma and Delta were the smallest (75 nm). Alpha and Gamma had the highest particle frequency per field at 48 hpi, while the same was observed for Zeta and Delta at 72 hpi and 24 hpi, respectively. The cycle threshold of viral RNA varied among the target protein, VOC, and time of infection. The findings presented here demonstrate that all four VOCs evaluated caused ultrastructural changes in Vero-E6 cells, which were more prominent when infection occured with the Delta variant.

A new approach for the treatment of Alzheimer’s disease: insulin-quantum dots

The potential use of insulin supplementation for Alzheimer’s Disease (AD) was aimed to investigate and explore CQDs as an alternative delivery system. CQDs were produced by microwave and characterised. Insulin-loaded Ins-CQDs and in-situ Gel-Ins-CQDs were developed. The in vitro release kinetics, penetrations of insulin through excised sheep nasal mucosa were determined. Toxicity of CQDs were calculated on SH-SY5Y cells. The stability and usability of the prepared formulations were assessed. The insulin release from the solution was 70.75% after 3 hours, while it was 37.51% for in-situ Gel-Ins-CQDs. IC50 value was 52 µM. The mean particle diameters of Ins-CQDs and in-situ Gel-Ins-CQDs varied between 8.35 ± 0.19 to 8.75 ± 0.03 nm during a 6-month period. Zeta potentials ranged from −31.51 ± 1.39 to −24.43 ± 0.26 mV, and PDI values were between 9.8 ± 0.01 to 5.3 ± 3.2%(SD, n = 3) for Ins-CQDs and in-situ Gel-Ins-CQDs, respectively. Our results show that Gel-Ins-CQDs represented a controlled release over time and can be used for AD through the nasal route.