Particle Diameter Research Articles

Study on the Effectiveness of a Copper Electrostatic Filtration System "Aerok 1.0" for Air Disinfection.

Bioaerosols can represent a danger to health. During SARS-CoV-2 pandemic, portable devices were used in different environments and considered a valuable prevention tool. This study has evaluated the effectiveness of the air treatment device "AEROK 1.0®" in reducing microbial, particulate, and pollen airborne contamination indoors, during normal activity. In an administrative room, airborne microbial contamination was measured using active (DUOSAS 360 and MD8) and passive sampling; a particle counter was used to evaluate particle concentrations; a Hirst-type pollen trap was used to assess airborne pollen and Alternaria spores. Statistical analysis was performed using SPSS 26.0; p values < 0.05 were considered statistically significant. The airborne bacterial contamination assessed by the two different samplers decreased by 56% and 69%, respectively. The airborne bacterial contamination assessed by passive sampling decreased by 44%. For fungi, the reduction was 39% by active sampling. Airborne particles (diameters ≥ 1.0, 2.0 μm) and the ratio of indoor/outdoor concentrations of total pollen and Alternaria spp. spores significantly decreased. The results highlight the effectiveness of AEROK 1.0® in reducing airborne contamination. The approach carried out represents a contribution to the definition of a standardized model for evaluating the effectiveness of devices to be used for air disinfection.

Ethanolic Cashew Leaf Extract Encapsulated in Tripolyphosphate–Chitosan Complexes: Characterization, Antimicrobial, and Antioxidant Activities

Ethanolic cashew leaf extract (ECL-E) is rich in phenolic compounds and shows remarkable antioxidative and antimicrobial activities. Encapsulation could stabilize ECL-E as the core. Tripolyphosphate (TPP)–chitosan (CS) nanoparticles were used to load ECL-E, and the resulting nanoparticles were characterized. The nanoparticles loaded with ECL-E at different levels showed differences in encapsulation efficiency (47.62–89.47%), mean particle diameters (47.30–314.60 nm), positive zeta potentials (40.37–44.24 mV), and polydispersity index values (0.20–0.56). According to scanning electron micrographs, the nanoparticles had a spherical or ellipsoidal shape, and a slight agglomeration was observed. The appropriate ratio of CS/ECL-E was 1:3, in which an EE of 89.47%, a particle size of 256.05 ± 7.70 nm, a zeta potential of 40.37 ± 0.66 mV, and a PDI of 0.22 ± 0.05 were obtained. The nanoparticles also exhibited high antioxidant activities, as assayed by DPPH and ABTS radical scavenging activities, ferric reducing ability power (FRAP), and oxygen radical absorbance capacity (ORAC). Low minimum inhibitory concentration and minimum bactericidal concentration were observed against Pseudomonas aeruginosa (9.38, 75.00 mg/mL) and Shewanella putrefaciens (4.69, 75.00 mg/mL). In addition, ECL-E loaded in nanoparticles could maintain its bioactivities under various light intensities (1000–4000 Lux) for 48 h. Some interactions among TPP, CS, and ECL-E took place, as confirmed by FTIR analysis. These nanoparticles had the increased storage stability and could be used for inactivating spoilage bacteria and retarding lipid oxidation in foods.

Effectiveness of Collars and Hooked-Collars in Mitigating Scour around Different Abutment Shapes

Abutment scour is a major cause of bridge failures worldwide, leading to disruptions, economic losses, and loss of life. The present experimental study examines countermeasures against abutment scour using hooked-collar protections on vertical-wall and wing-wall abutments (at 45° and 60°) under different flow conditions. All 60 experiments were performed under sub-critical flow conditions by investigating scour around an abutment 20 cm long, 20 cm wide, and 25 cm tall. Two distinct values of the Froude number, 0.154 and 0.179, and a sediment particle diameter (d50) of 0.88 mm were used throughout the experimental phase. The resulting equilibrium scour around the abutments was compared to those with collar and hooked-collar protections. It was determined that the maximum abutment scour depth reduction was 83.89% when hooked collars were placed on vertical wall abutments beneath the bed surface level, and for wing-wall abutments at 45° and 60°, it was 74.2% and 73.5%, respectively, at the bed surface level. Regression analysis was conducted to assess the non-dimensional scour depth (Ds/Yf) and scour reduction (RDs/Yf), with a high enough coefficient of determination (R2 values of 0.96 and 0.93, respectively), indicating high confidence in the analysis. The sensitivity analysis findings demonstrate that the width of the collar (Wc) and La are the most influencing factors affecting Ds/Yf and RDs/Yf.

Insights of mechanism and kinetics of acrylonitrile aqueous precipitation polymerization

Aqueous precipitation polymerization is commonly used in the industry due to its efficient heat dissipation, reaction stability and production flexibility. However, its mechanisms and kinetics are still partially unclear. The ammonium persulfate-ammonium sulfite monohydrate (APS-AS) initiated aqueous phase precipitation polymerization of acrylonitrile (AN) at low concentration was deeply investigated, with the APS initiation system as a control. The apparent kinetic equations for the APS and APS-AS initiation systems were determined to be Rp= K[AN]1.706[(NH4)2S2O8]0.704 and Rp= K[AN]3[(NH4)2S2O8]0.704[(NH4)2S2O3]−1.055, respectively. Monitoring AN distribution in the aqueous and polyacrylonitrile (PAN) phases revealed a rapid transition of the reaction site from the aqueous phase to the PAN phase following polymer precipitation. Zeta potential and primary particle number exposed that the nucleation site disparities between initiation systems led to different predominant factors affecting the polymerization rate. The change in molecular weight during polymerization had a maximum due to its dependence on the monomer concentration. The crystallinity of the product initially increased during polymerization, then decreased and eventually stabilized. Scanning electron microscopy (SEM) revealed that the diameter of the internal particles was larger, while the surface particles were smaller after coagulation. These findings offer crucial insights for optimizing aqueous precipitation polymerization and PAN particle property control.

Effect of particle size on SiO2 nanofluid viscosity determined by a two-step method

AbstractAccording to review of the literature, the influence of nanoparticle diameter with irregular shapes on viscosity requires further research since there is no relation between particle size and nanofluid stability. In this study, SiO2/EG–water-based nanofluid samples were prepared, and their viscosities were experimentally determined. SiO2 nanoparticles had sizes of 7, 15, and 40 nm, and the base fluid was a 50% ethylene glycol and 50% water mixture. Nanofluid samples were prepared using a two-step technique. Viscosity change was measured every 10 °C from 20 to 60 °C. The maximum viscosity values were observed for 7, 15, and 40 nm particles over an entire concentration range. Considering all measurements, the highest viscosity increase was 60.51% for 3% SiO2 (7 nm) at 60 °C, and the lowest viscosity change was 7.72% for 1% SiO2 (40 nm) at 40 °C. The most stable sample of the current study was 1% SiO2 (15 nm), and its Zeta potential was − 35.6 mV. Finally, a new empirical equation that included temperature, particle diameter, and concentration terms is suggested to predict dynamic viscosity, with R adj 2 = 0.98. It was also compared with previous correlations.

Electrophoretic mobility of nanoparticle aggregates: Independence from aggregate size

The zeta potential is a widely used parameter to categorize particle-particle interaction and aggregation. This parameter is often determined by the measurement of electrophoretic mobility. For single particles, various approximations allow a direct correlation between the mobility and the zeta potential. However, for aggregates, which are often found in the environment and in industrial applications, such approximations are less utilized. The relation between the size of aggregates and the resulting electrophoretic mobility has not yet been extensively explored and is often not considered. Here, we control the aggregate size additive-free of two fumed silica types with different primary particle diameters for comprehensive electrophoretic and dynamic light scattering measurements. We evaluate the influence of primary particle diameter and aggregate size on electrophoretic mobility. Our results reveal that the primary particle diameter is the defining factor for the electrophoretic mobility of the aggregates. This finding provides new insights into the electrokinetic behavior of aggregates and emphasizes the importance of primary particle properties in predicting colloidal interactions.

Effect of powder feeding rate and size on the critical velocity and mechanical properties of cold sprayed Al2O3/2024 deposit

The particle acceleration behavior and deposition mechanism of cold spraying aluminum matrix composites (Al2O3/2024) are complicated by the addition of ceramic particles. The effects of different feeding rates and particle diameters on critical velocity and mechanical properties were studied by numerical simulation and experiment. The results indicate that as the powder feeding rate increases, the impact velocity of gas and particles gradually decreases, and the temperature of gas and particles increases, resulting in an increase in the difference between particle impact velocity and critical velocity. The highest tensile strength of the deposit is achieved at a powder feeding rate of 1 r/min, which is 343 MPa. As the powder feeding rate increases, the performance of the deposits decreases, but it significantly saves time and cost. As the particle diameter increases, the impact temperature first increases and then decreases, resulting in the critical velocity first decreasing and then increasing, and the mechanical performance first increasing and then decreasing. To some extent, the best performance of the deposit is achieved when the size of the metal particle is close to that of the ceramic particle.

Experimental and modelling studies on static sag of solid weighting powders in Polysulfonate workover fluids at high temperature and high pressure

The solid weighting material in a high-density workover fluid is prone to static sag. Existing experimental methods cannot predict the parameters of the settling stability of workover fluids at high temperature and high pressure (HTHP). Therefore, in this study, static settlement experiments were carried out using a novel experimental setup. The experimental setup enables the measurement of the density profile of heavy workover fluids at HTHP. A multi-parameter correlation equation between the sag factor and particle diameter, particle density, base fluid density, workover fluid density and rheological parameters, aging time, temperature, and pressure was obtained using dimensional analysis and multivariate nonlinear regression methods. The results reveal that the settlement stability of the workover fluid decreases with the increase in temperature and pressure. Based on the multi-parameter correlation, the predicted and the measured values were compared and verified. The error between the predicted value and the measured value was within 5%. The average prediction error was 1.68%, and the maximum prediction error was 3.8%. These results reveal that the model proposed in this study can effectively predict the static sedimentation stability of the solid weighted Polysulfonate workover fluids. Furthermore, the proposed correlation can guide the properties adjustment of the workover fluids to achieve the required sag stability. This work provides a new approach to predict and control the sag stability of the solid weighted workover fluids.

Abstract MP28: Advanced Lipid Status Parameters in Women With Preeclampsia

Preeclampsia (PE) is a hypertensive disorder associated with pregnancy, usually occurring after the 20th week of gestation, followed by proteinuria or signs of end-organ dysfunction. Early-onset preeclampsia is associated with placental dysfunction, while late-onset preeclampsia is recognized as a maternal disorder, influenced by risk factors like maternal obesity, diabetes mellitus, or chronic hypertension. During physiological pregnancy, lipid metabolism changes to adequately supply the fetoplacental unit with nutrients and energy, consequently changing the composition of LDL and HDL particles. However, in preeclampsia, these changes become atherogenic. The study aimed to examine changes in advanced lipid status parameter concentrations and the dominant diameter of LDL and HDL particles during pregnancies affected by PE. In this study, 92 pregnant women at high risk for complication development were followed longitudinally throughout the first (T1), second (T2), and third (T3) trimesters. They were classified into high-risk (HR) (72 women) and PE (20 women) groups based on pregnancy outcomes. Total cholesterol (TC), HDL-C, triglycerides (TG), apoAI, and apoB concentrations were measured using commercial kits, while LDL-C concentrations and the atherogenic index of plasma (AIP) were calculated using established equations. Dominant LDL and HDL particle sizes were determined by gradient gel electrophoresis. TG levels were significantly higher in the PE group compared to the HR group across all trimesters (p&lt;0.05; p&lt;0.05; p&lt;0.01), while AIP was significantly elevated in T2 (p&lt;0.01) and T3 (p&lt;0.01). HDL-C levels were lower in the PE group than in the HR group in T2 (p&lt;0.05). In the HR group during pregnancy, concentrations of TC, TG, LDL-C, apoB, as well as HDL-C increased significantly (p&lt;0.05 for all parameters), while the dominant LDL diameter decreased markedly (p&lt;0.001) between all trimesters, without changes in the dominant HDL diameter. There were no changes in HDL-C concentration during pregnancy in the PE group. In contrast, TG concentrations increased significantly (p&lt;0.01), accompanied by a significant decrease in dominant LDL particle diameter (p&lt;0.05). In conclusion, pregnant women with PE exhibit atherogenic changes in lipid status parameters, including no increase in HDL-C concentration, potentially leading to a loss of HDL's protective effect.

Permissible Extrapolation Justification of the Multiplicative Multifactorial Model and Its Application to the White Soot Production Technology

The solution to a specific technological problem is combined with the methodological development of a nonlinear multifactorial relationship to justify the boundaries of its extrapolation beyond the experimental range used. White soot was produced through two-stage carbonization of a silicate solution (composition, g/l: Na2O = 126.5, SiO2 = 107.7, Al2O3 = 3.1), obtained after processing waste tailings with carbon dioxide in a recirculation system. The influence of the deposition duration, temperature, and final pH value of the pulp on the formation of the specific surface area (Ssp, m2/g) of white soot was studied. The specific surface area was calculated from the average diameter of the white soot particles measured using an electron microscope. A multifactorial experiment was designed, and the experimental results were processed using a probabilistic deterministic method for experiment design (PDED) to obtain a nonlinear multiplicative combined model. A new interpretation of the subordination of the nonlinear multiple correlation coefficient R and the R2 value was given as relating to the structural and adaptive components of complex self-organizing systems. This determines their use for assessing the ratio of the basic R and extrapolated R2ranges of variation for each factor and any combinations thereof and multifactorial dependence in general. The results are presented in the form of multifactor tabular nomograms measured by the number of multifactor cells in localized areas of optimal sets that allow isolation by one or another combination of factors. The technological object of extrapolation of the ‘white soot’ production is linked to the solution of emerging methodological problems and illustrates the accessibility of the engineering application of the proposed method for combining nonlinear and linear approaches to mathematical experimental design. Doi: 10.28991/HIJ-2024-05-03-08 Full Text: PDF

Numerical study on the motion of two parallel spherical particles with different diameters in upward flow

The settling of particles is related to many industrial processes and research fields. However, due to the complex particle–particle and particle–fluid interactions, the settling mechanism of particles in flowing fluids is not fully understood. This article conducts numerical research on the settling process of two particles with different diameters in parallel in upward flow using the immersion boundary method. The numerical method was validated against experimental results including one particle settling, two parallel particles settling, and two series particles settling. The effects of large particle diameter, upward flow velocity, and initial particle spacing on the settling process were explored. The results indicate that the two particles with same diameter will repel each other when settling in upward flow. Moreover, when the diameters differ, the two particles can experience both attractive and repulsive interactions. The larger the diameter of the large particle, the stronger its attractive influence on the small particle. When the diameter of large particle d2 = 3.0d1, large particle only has an attractive effect on small particle. The wake of each particle forms a distinct velocity boundary with the upward fluid. As the upward flow velocity increases, the interactions between the two particles become increasingly intense. With increasing initial spacing between the particles, their mutual interactions gradually weaken.

Particle shape descriptors as a tool for classification of grain breakage

This study explores particle breakage of a calcareous sand, utilising dynamic image analysis and direct shear tests at varying normal stress levels to analyse the sand crushing mechanism. Tests were arrested at four phase transition points encountered during shear. Particle breakage was traced along a proposed scale based on the literature. Distinct behaviours in shape descriptors for particles of different diameters were observed under changing stress conditions. Agglomerated particle-level behaviour indicates that applied stress levels lead to different soil responses; at low stress, grains roll or slide, whereas at high stresses, grain movement is restricted. Particle breakage was evident even at minimal stress, with increasing grain size reduction as shear strain and stress levels heightened. This study introduces a parameter loading intensity (LI), amalgamating the effects of force chains and loading duration to model grain crushing. Relationships among the shape-angularity group indicator (SAGI), convexity (Cx) and sphericity (S) were also established, enabling calculation of these descriptors, after any loading intensity is applied, based on the initial values. Finally, a methodology for forecasting changes in S and Cx, under any given LI for materials with a known SAGI is presented.

Engineering of Layer-by-layer Acetate-coated Paclitaxel Loaded Poly(lactide-co-glycolide) Acid Nanoparticles for Prostate Cancer Therapy- in vitro

It is hypothesized that layer-by-layer acetate-coated Paclitaxel-loaded PLGA nanoparticles (F2) can be engineered to potentiate the effectiveness of Paclitaxel (PTX) on LNCaP, a human prostate cancer cell line. The core of the layer-by-layer NPs is formed by nanoprecipitation, and the shell of the NPs is engineered using the sodium acetate's unique coating mechanism and surface-active properties. The resulting nanoformulation physicochemical properties are characterized by Fourier Transform Infra-Red (FTIR), Differential Scanning Calorimetry (DSC) Transmission Electron Microscopy (TEM), NanoSight NS300, spectrophotometry, Korsmeyer-Peppas model, respectively. The NP's cytotoxicity on LNCaP is assessed by MTS assay. The DSC and the FTIR confirm SA's coating of the NPs. The particle's mean diameters (PMD) are 89.4±2.3- to 114.4±7.6 nm. The TEM shows a unique multilayer and spherical nanoparticle. The encapsulation efficiency of commonly PTX-loaded PLGA NPs (F1) and F2 are 84.37±2.71% and 86.74±2.22, respectively. The drug transport mechanism of F1 and F2 is anomalous transport and case II, respectively. F2 follows a zero-order release mechanism. The cell viability is 45.08±2.18% and 60.17±4.72% when LNCaP is treated with 10 µg/mL of F2 and F1, respectively, after 48 hours of exposure. F2 and F1 cell growth inhibition are dose-dependent. This unique process of engineering the layer-by-layer NPs will provide new horizons for developing future innovative nanoparticles for targeted prostate cancer therapy.

An approach of analyzing gas and biomass combustion: Positioned of flame stability and pollutant reduction

Biomass, as a renewable energy source, has gained attention as a sustainable alternative to conventional fuels due to its global availability and usability in rural areas. However, biomass combustion presents challenges such as flame instability and pollutant emissions. This study compares the use of methane gas, wood shavings, and a combination of these two fuels, examining the effects of preheating and flame stability in the combustion of natural gas, biomass, and their co-firing using numerical methods. An equivalence ratio of 1 has been used to avoid a rich-fuel mixture, and an air mass flow rate of 0.0001 kg/s are considered to ensures a sufficient supply of oxygen for the combustion process. Biomass fuel particles are injected from the surface of the fuel and its particle diameter ranging between 5 and 10 μm. The results showed that using the combined fuel not only increased the flame temperature at the beginning of the combustion chamber but also achieved more complete and stable combustion, with over 97 % of the fuel consumed at the start of combustion. As a result of this complete combustion, the emissions of toxic gases CO and NOx in the combustion products reached zero. Additionally, preheating the air increased the flame temperature by 14 %, while preheating the fuel reduced NOx emissions by 24 %.

Intercomparison of optical scattering turbidity sensors for a wide range of suspended sediment types and concentrations

To monitor the effects of rapid changes in climate and land use on sediment export from erodible environments, it is crucial to accurately quantify highly fluctuating suspended sediment concentrations (SSCs) in contrasted river systems that drain small to mesoscale catchments. To this end, we investigate the turbidity-based quantification of SSCs in the range of 0.05–100 g/L through laboratory experiments performed with 7 different types of turbidity sensors and sediments from 10 watersheds. We find that measurements of scattered light from multiple angles may allow for: (1) an extended monitoring range with SSCs up to 10–100 g/L, where enhanced uncertainty may occur near the transition in the effective operational ranges of the underlying signals (typically somewhere in the range of 1–10 g/L); and/or (2) a slightly reduced sensitivity to sediment properties. The specific turbidity of the investigated sensors is inversely related to particle diameter (D10) for SSCs up to 1–5 g/L. Backscatter and combined-signal sensors also show a dependency on sediment colour (CIE a∗), which becomes particularly prominent at SSCs above 10 g/L. We relate this increase in colour dependency with SSC to the expected effect of cumulative near-infrared light absorption associated with multiple scattering. We discuss covarying physical properties of naturally occurring river sediment that can dampen or enhance measurement sensitivity and result in turbidity-based SSC rating curves that may strongly differ in magnitude and form from curves derived for industrially prepared material that is often used for sensor calibration. Although the differences in SSC per sensor among sediment types are generally less than one order of magnitude, the systematic errors and uncertainties associated with high SSCs are typically greater than one order of magnitude and may disproportionally affect the quantification of sediment loads during large-magnitude flow events.

Green Synthesis of Nanocomposite: Based on [Eugenol and Metal Oxides], Characterization and Biomedical Applications

تم تفاعل الأوجينول (EUG) كمادة أساس مع خليط من أكاسيد المعادن (ZnO و CuO) التي تم تحضيرها من خلات المعدن، Zn (CH3CO2)2 و Cu (CH3CO2)2 كمواد أولية واستخدام الكلايكول إيثيلين (EG) كمذيب لتخليق المتراكب النانوي [Eug/ ZnO: CuO] باستخدام طريقة .Sol-Gel تم تشخيص المتراكب النانوي المحضر باستخدام التقنيات (FT-IR, AFM, SEM, EDX, و(XRD, حيث وجد أن متوسط ​​قطر الجسيم يقع ضمن نطاق المقياس النانوي. ولوحظ أيضاً أن المادة النانوية المحضرة كانت على شكل قضبان ذات توزيع متجانس جيد. من أجل الوقوف على الخواص النانوية التي تم الحصول عليها، تم توظيف تلك الخواص من حيث البعد النانوي وخصائص الشكل، لدراسة فعالية المتراكب النانوي المحضر [Eug/ ZnO: CuO] كنشاط مضاد للميكروبات (مضاد للبكتيريا ومضاد للفطريات) ضد نوعين من البكتيريا [Escherichia Coli (-) (E. coli), and Staphylococcus aureus (+) (S. aureus)], ونوع واحد من الفطريات [Candida albicaus (C. albicaus)], حيث أظهرت نتائج مقبولة. كما تم قياس فعالية المتراكب النانوي المحضر كمضاد للأكسدة ضد الجذور الحرة وأظهر نسبة كسح جيدة. بالإضافة إلى ذلك تمت دراسة التأثير السمي الخلوي للمتراكب النانوي [Eug/ ZnO: CuO] على خلايا سرطان الثدي (MCF-7)، وأظهر نتائج مقبولة في قتل الخط الخلوي (MCF-7) بتراكيز عالية.

Green Synthesis of Gold Nanoparticles Using Basella alba Leaf Extract and Their Antioxidant Activity

In this research, gold nanoparticles were synthesized using the green synthesis method with the bioreduction extract of Basella alba leaf infusion. This research aims to characterize gold nanoparticles synthesized using UV-Vis spectroscopy and TEM and assess their antioxidant activity, which is quantified by the IC50 value. The UV-Vis spectrophotometric characterization of the gold nanoparticles revealed an absorption peak at a maximum wavelength of 543 nm. TEM characterization indicated a particle diameter of 9.463 ± 2.273 nm. The antioxidant activity was evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) reduction method with concentration variations of 2.5, 5, 10, and 20 ppm, resulting in reduction percentages of 40.6%, 44.3%, 57.4%, and 77.9%, respectively, and an IC50 value of 7.05 μg/mL, indicating very strong antioxidant activity. Based on these findings, it can be concluded that Basella alba leaf infusion extract is effective as a biological reducing agent in synthesizing gold nanoparticles, and the resulting nanoparticles show significant potential as antioxidants for reducing free radicals.

Increasing particle-size by air-flow modification – An experimental study

Ambient particulate are characterize by submicron particles that may penetrate deep into the lungs, where they become harmful due to their morphology and composition, or due to their role as carriers of harmful chemicals or biological agents. Particle filtration technologies have in general a lower efficiency at diameter size around 0.1–0.3 μm. This study examines the concept of particle grouping as a means to overcome this size-gap, for improving air purification or filtration systems. The grouping manipulation is induced by a controlled rotating valve which creates a sinusoidal flow in the experimental tube, and by modules with varying diameter, forcing a wavy flow. Fine particles with a known size distribution which are introduced into the manipulated flow, exhibit groups of particles in the outflow, hence increase the effective size of the particles. Former successful studies were performed with high flow velocity and particle load of industrial duct and car engine outflow, while in the current study smaller particle loads representing ambient to indoor levels are in operation. Although the low velocity and particle load are challenging, this study shows a promising shift of the particle size distribution from a peak at 0.2–0.3 μm, towards larger particle diameters. Fine powder of dolomite is used in this study and preliminary results of adhesion experiments related to dolomite are also reported.

Molecular dynamics study of the influence of carbon impurity on austenite nanoparticles crystallization during rapid cooling

The molecular dynamics method was used to study the structure formation during austenite nanoparticles crystallization in the presence of carbon impurities. The paper describes the dependence of the melt cooling rate, particle size, concentration of carbon atoms in the particle on the resulting structure features during crystallization and temperature of the crystallization onset. Formation of the nanocrystalline structure of nanoparticles can be controlled by varying the cooling rate and introducing a carbon impurity: at a cooling rate above 1013 K/s in the model used, crystallization did not have time to occur; at a rate below 5·1012 K/s, the austenite particle crystallized to form a nanocrystalline structure. At the same time, with a decrease in the cooling rate, a decrease in the density of defects in the final structure was observed. At a rate of 5·1011 K/s or less, crystallization of carbon-free particles took place with the formation of low-energy grain boundaries (with a high density of conjugate nodes: special boundaries, twins). The crystallization temperature during cooling at a rate below 1012 K/s is inversely proportional to the particle diameter: as the particle size decreases, the proportion of free surface increases, which leads to a decrease in the probability of crystalline nuclei formation. In addition, the crystallization temperature increases with a decrease in the cooling rate. The introduction of a carbon impurity led to a decrease in the crystallization temperature of nanoparticles: in the presence of 10 at. %. As a percentage of carbon, it decreased by about 200 K for particles of different sizes. Carbon atoms often formed clusters consisting of several carbon atoms. Such clusters distorted the resulting crystal lattice of metal around them, preventing crystallization. In the presence of a carbon impurity, the final structure of the crystallized particles contained a higher density of grain boundaries and other defects. Carbon atoms, especially clusters of them, were fixed mainly at grain boundaries and triple joints.

Probiotic Encapsulation: Bead Design Improves Bacterial Performance during In Vitro Digestion (Part 2: Operational Conditions of Vibrational Technology).

The development of functional foods is a viable alternative for the prevention of numerous diseases. However, the food industry faces significant challenges in producing functional foods based on probiotics due to their high sensitivity to various processing and gastrointestinal tract conditions. This study aimed to evaluate the effect of the operational conditions during the extrusion encapsulation process using vibrating technology on the viability of Lactobacillus fermentum K73, a lactic acid bacterium with hypocholesterolemia probiotic potential. An optimal experimental design approach was employed to produce sweet whey-sodium alginate (SW-SA) beads with high bacterial content and good morphological characteristics. In this study, the effects of frequency, voltage, and pumping rate were optimized for a 300 μm nozzle. The microspheres were characterized using RAMAN spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy. The optimal conditions for bead production were found: 70 Hz, 250 V, and 20 mL/min with a final cell count of 8.43 Log10 (CFU/mL). The mean particle diameter was 620 ± 5.3 µm, and the experimental encapsulation yield was 94.3 ± 0.8%. The INFOGEST model was used to evaluate the survival of probiotic beads under gastrointestinal tract conditions. Upon exposure to in vitro conditions of oral, gastric, and intestinal phases, the encapsulated viability of L. fermentum was 7.6 Log10 (CFU/mL) using the optimal encapsulation parameters, which significantly improved the survival of probiotic bacteria during both the encapsulation process and under gastrointestinal conditions compared to free cells.