Bead Size Research Articles

Modelling and Prediction of Process Parameters with Low Energy Consumption in Wire Arc Additive Manufacturing Based on Machine Learning

Modelling and Prediction of Process Parameters with Low Energy Consumption in Wire Arc Additive Manufacturing Based on Machine Learning

Environmentally Friendly Synthesis of Polymer Nanoparticles in a Packed Reactor Using Glass Beads

AbstractPolymeric particles less than 100 nm in size (polymer nanoparticles), which are useful in the fields of medicine and so on, are synthesized through emulsion polymerization, wherein surfactants are essential for maintaining their dispersion stability, contaminating particle surfaces and causing high environmental pollution. The soap‐free emulsion polymerization (SFEP) of styrene in a packed reactor using microglass beads enables the synthesis of polymer nanoparticles without surfactants. Ultraviolet irradiation is used for radical polymerization using an initiator during the SFEP of styrene. The reaction space in the packed reactor is controlled by the size of glass beads to be filled in the reactor. A decrease in the size of the glass beads narrows the reaction space, causing the average polystyrene particle size to reach 27.3 nm and suppress convection flow by the wall of the glass beads, thereby limiting particle motion and preventing particle growth through particle collisions.This article is protected by copyright. All rights reserved

Adhesion characteristics of carbon nanotube gecko tapes for micrometer-sized particles

ABSTRACT A detailed understanding of the adhesive properties of a carbon nanotube (CNT)-based gecko tape with respect to microscale particles is necessary for its practical application as a supporting medium for specific solid materials. We obtained the force curves of vertically aligned CNTs (VACNTs) for individual microparticles of various diameters using atomic force microscopy and evaluated their adhesion force and adhesion length. The measured adhesive force followed the apparent contact area with increasing embedding depth and was size-dependent at scales of several tens of micrometers. The adhesive forces measured for a 20 µm-diameter bead was significantly higher than those for larger particles, which may be related to inclination of the adherent surface against the VACNT tape surface. The adhesion length depended on the type of the CNTs comprising the VACNT, rather than on the bead size. The evaluation of VACNTs with different morphologies suggested that the flexibility of the individual CNTs and the density of the CNT – CNT interconnections in the VACNTs were important factors for obtaining the true contact area to realize better adhesion of micrometer-sized particles.

Effects of Mango Pectin Concentration on the Calcium Pectate Bead Properties and on the Cell Leakage of Yeast (Saccharomyces cerevisiae) Immobilized by Entrapment Technique

Immobilized yeast cells have advantages for use in industries due to their stability, viability, and productivity. As a support material, pectin is suitable because of its stability, strong mechanical attributes, and favorable absorption properties. In this study, the influence of mango pectin concentration on the CP bead characteristics and the leakage of immobilized yeast cells were determined. Results have indicated that yeast cells can be immobilized using low-methoxyl pectin (LMP) from mango peels via entrapment technique. Pectin concentration did not affect the size (3.0323 to 3.4315 mm) of the CP beads. Only 5% and 7% (w/v) pectin concentrations produced spherical beads (SF<0.05). Increasing the pectin concentration from 3% to 7% (w/v) resulted in a 36.21% decrease in swelling ratio for CP beads with yeast. The pectin concentration significantly affects the cell leakage (p-value<0.05). The results further indicate the feasibility of using locally available materials as a matrix for immobilization.

Discrete-to-continuum models of pre-stressed cytoskeletal filament networks

We introduce a mathematical model for the mechanical behaviour of the eukaryotic cell cytoskeleton. This discrete model involves a regular array of pre-stressed protein filaments that exhibit resistance to enthalpic stretching, joined at cross-links to form a network. Assuming that the inter-cross-link distance is much shorter than the length scale of the cell, we upscale the discrete force balance to form a continuum system of governing equations and deduce the corresponding macroscopic stress tensor. We use these discrete and continuum models to analyse the imposed displacement of a bead placed in the domain, characterizing the cell rheology through the force–displacement curve. We further derive an analytical approximation to the stress and strain fields in the limit of small bead radius, predicting the net force required to generate a given deformation and elucidating the dependency on the microscale properties of the filaments. We apply these models to networks of the intermediate filament vimentin and demonstrate good agreement between predictions of the discrete, continuum and analytical approaches. In particular, our model predicts that the network stiffness increases sublinearly with the filament pre-stress and scales logarithmically with the bead size.

Studies on Encapsulation of Gas Releasing Agent in Ca-Alginate Beads and Controlled Release Pattern of the Beads

Calcium alginate beads have been used to control release gases and volatile compounds for agricultural applications, drug delivery, waste treatment, and food product enhancement. The release rate of the gas and vapor depends on the diffusion of gas and vapor through the Ca-alginate gel matrix. However, the knowledge about the effect of process variables on the diffusion rate of gas and vapor still needs to be improved. Therefore, this study aims to investigate the effect of alginate concentration, gas release agent concentration, and bead size on the concentration of gas released from Ca-alginate beads. In this study, calcium carbonate was used as the model gas release agent, encapsulated in Ca-alginate beads to release carbon dioxide when the beads reacted with an acetic acid solution. The results showed that the concentration of carbon dioxide released by the beads depended on the bead diameter. The gas release rate was increased when the diameter of the beads was increased. The total amount of gas produced by the large beads was observed to be higher than that of small beads. Compared to small beads, large beads take longer to react completely to produce carbon dioxide gas. It was also found that the amount of carbon dioxide produced by the Ca-alginate beads was inversely proportional to alginate concentration but directly proportional to calcium carbonate concentration. The results indicated that the gas diffusion rate of the Ca-alginate beads can be tailored by adjusting the process variables of the Ca-alginate bead encapsulation process.

Fiber Optic Assisted Optofluidic Viscometer for Biomedical Applications

Fiber Optic Assisted Optofluidic Viscometer for Biomedical Applications

Novel colorimetric indicators based on alginate hydrogel beads containing anthocyanin for visual freshness monitoring of shrimp and minced chicken

Novel colorimetric indicators were developed by incorporating anthocyanins into alginate hydrogel beads through electrostatic extrusion for intelligent packaging. Two different sizes of hydrogel beads were produced and applied into shrimp and minced chicken packaging to visually detect freshness status during 4 °C storage. To assess the freshness of the products, the viable count of various types of bacteria (psychrotrophic, H2S-producing, mesophilic, and Pseudomonas spp.), total volatile basic nitrogen (TVB-N) content, pH, K-value, H-value, and biogenic amines level were analyzed. The indicators' color change (ΔE) was then correlated with these parameters. Color analysis of the indicators during storage indicated ΔE values below 10 and over 30 in the hydrogels incorporated into minced chicken and shrimp packaging, respectively. The color change of both indicators integrated into the shrimp package was strongly correlated with the change in viable counts, TVB-N, pH, K-value, and H-value (r ≥ 0.8, p < 0.016), as well as biogenic amines (r = 0.7, p < 0.05). The indicators applied to minced chicken packaging showed subtle color changes during storage, while those in shrimp packaging consistently reflected shelf-life variations. This innovative approach shows potential for improving food safety and quality monitoring, particularly in seafood packaging, where indicators have been effective in visually signaling product freshness.

Development and analysis of diethylaminoethyl silica-based adsorption column for removing antibiotic resistance genes from wastewater

The current study investigates the efficiency of diethyl aminoethyl silica gel (DEAE-Si) based adsorption column for removing antibiotic resistance genes from secondary treated wastewater. Various column parameters like packing shape, packing size, bed height, and flowrate were analyzed to study their effect and optimize the column performance. The adsorption capacity of the column varied in range of ∼4.5 to 7.8 μg/g of DNA adsorbed. For regular packing of spherical shape, 3 mm–5 mm beads size, 8 cm column height, and flow rate of 0.5 mL/min. Adsorption capacity of 6.23 μg/g with 20 h of break through time and 36 h of saturation time was attained. The column regeneration was performed using NaCl solution at pH 8.5 ± 0.5. High removal efficiency of around 90 % up to 3 regeneration cycles, 75 % for 4th regeneration cycle, and >50 % for 5th regeneration cycle was attained. For practical understanding and to check how the column would perform for increased volumes of wastewater 10 times larger sized column was analyzed in simulated and real secondary treated wastewater matrix. The adsorption capacity attained using large column was around 4.65 μg/g at higher flowrate of 5 mL/min. and constant empty bed contact time resulting in treating up to 17.1 L of wastewater. The overall performance of large column was satisfactory and comparable with the test column in simulated wastewater matrix. >80 % removal efficiency of ARGs of different size in real secondary treated wastewater matrix was achieved on maintaining low flowrate.

Two‐Photon Direct Laser Writing of pNIPAM Actuators in Microchannels for Dynamic Microfluidics

Microfluidic tools enable to investigate and manipulate various chemical and biological processes at small scales. As a result, it finds widespread applications in lab‐on‐chip devices, drug delivery systems, or miniaturized cell cultures. However, microfluidic devices are still limited in their flexibility and are often designed to fulfill a single functionality. Moreover, technologies to introduce dynamic functionalities with high precision and at high resolution after the development of a continuous phase microfluidic chip remain scarce. Herein, two‐photon polymerization direct laser writing is introduced as a suitable approach to equip continuous phase microfluidic chips with structurally defined thermoresponsive poly(N‐isopropyl‐acrylamide) (pNIPAM) microactuators. Harnessing the lower critical phase transition temperature of pNIPAM, and upon controlling specific design parameters, the efficient catch and release of polystyrene beads of different sizes using a pNIPAM micropillar brush array is demonstrated. Moreover, a biocompatible pNIPAM microgripper array is designed to subsequently capture and release differently sized (single) cell populations. Overall, the method offers great flexibility and a high degree of freedom toward the fabrication of dynamic microfluidic devices with great adaptability to experimental conditions in real time.

Antifungal Capacity of Microcapsules Containing Lactiplantibacillus plantarum TEP15 or Lactiplantibacillus pentosus TEJ4

The use of lactic acid bacteria (LAB) for the biocontrol of fungi that cause fruit and vegetable deterioration is a highly promising strategy. However, one of the main challenges lies in maintaining both viability and antifungal activity even in conditions that are unfavorable for LAB. The microencapsulation of LAB can minimize the impact of environmental conditions, helping to maintain viability, but there is still little information on what occurs with respect to antifungal activity. Therefore, the objective of this study was to evaluate the effect of microencapsulation with several polymer blends on the viability and antifungal activity of Lactiplantibacillus plantarum TEP15 and L. pentosus TEJ4. Sodium alginate (2%), sodium alginate–gum arabic (2%:1%), sodium alginate–k-carrageenan (2%:0.05%), and sodium alginate–whey protein (0.75%:1.5%) were used as encapsulating polymers. After processing (day 0), as well as after 14 and 28 days of storage, the encapsulation efficiency, moisture content, bead size, and survival were evaluated. Likewise, the encapsulated bacteria were subjected to in vitro tests against Colletotrichum gloeosporioides, Penicillium AT21H10, and Fusarium sp. Capsules with sizes ranging from 1.47 mm to 1.88 mm were obtained, and all the wall materials tested had more than 85% encapsulation efficiency and allowed survival rates greater than 90% and 80% to be maintained after 14 and 28 days of storage, respectively. The encapsulated LAB inhibited the growth of mycelia by up to 100%, but, against spores, the greatest inhibition was 22.08% for all the fungi tested.

Horseradish peroxidase immobilized in calcium alginate-gelatin hybrid beads with high stability against metallic ions and organic solvents

Horseradish peroxidase (HRP) was immobilized in hybrid calcium alginate-gelatin hydrogel beads by entrapment. Then, organic solubility, metal ion compatibility, pH/temperature studies of the synthesized materials have been carried out. Hybrid beads (Ca-Alg@gel-HRP) were synthesized under optimum synthesis conditions with high yield and specific activity. The synthesized bead size was determined to be approximately 0.29 mm in diameter, hydrogel structure and transparent appearance. Accordingly, the optimum pH of free HRP and Ca-Alg@gel HRP was found to be pH 6 and 5 and the optimum temperature was found to be 40 °C and 60 °C respectively. For all identified metal ions except Fe2+, the Ca-Alg@gel HRP had a higher activity than the free HRP. In the presence of 1 mM Na+, Ca2+, Mg2+, Ba2+, Cu2+, Ni2+, Mn2+, Hg2+ ions, the activity increased by more than 20%. The relative activity was also approximately 153%, 150% and 145% in 2.5 mM chloroform, glycerol and DMF. Free enzyme activity was reduced by more than 30%. The Ca-Alg@gel HRP at room temperature and 4 °C retained most of its activity after 14 days. In cycle 5, it had half the activity. As a conclusion, it may have significant potential in a number of industrial processes, particularly in organic synthesis, because it is tolerant to metal ions and organic solvents and is a cheap, practical and simple immobilization method.

Effect Of Different Variables On The Formulation Of Sodium Alginate Beads

This work examined the possibility of encapsulating prednisolone as drug modelling in Na-alginate polymeric beads. Our beads were formulated by ionotropic gelation method using Na-alginate as an anionic natural polysaccharide polymer and Cacl2 as a positive charge cross-linker. Eleven formulations were successfully created, and different variations were evaluated, including Na-alginate concentration ( 0.5, 2, 3) w/v %, Cacl2 concentration (1, 3, 5) w/v % stirring speed (100, 300, 400) rpm, the addition of tween-80 (0, 2.5, 5) ml, washing beads with alcohol, change curing time. The beads were assayed by bead size, morphology, drug loading, encapsulation efficiency, yield and FTIR. The results showed that the best formula was F2 which can be obtained when using a high concentration of Na-alginate (2 w/v %), Cacl2 (5 w/v %), the addition of tween-80 (5ml) with the lowest stirring speed (100 rpm) without increase curing time or washing with alcohol. Also, the FTIR result revealed a shifting of the carbonyl group and a low intensity of the hydroxyl group in the spectrogram of F2, indicating potential hydrogen bond interactions that might have resulted in the creation of beads.

Determining differences in the timing of fish feed intake using a novel dual ballotini X-radiography method

Fish feeding behaviour can be complicated and time consuming to observe, analyse and quantify. The conventional single ballotini X-radiography method was modified to determine the timing of feeding within a meal in farmed fish reared at commercial densities. Feed pellets containing two bead sizes were fed at different times during a single meal, either for the first half or second half of the meal. The two different ballotini sizes were differentiated on X-radiographs by human eye and semi-automated bead counting software was able to count the different bead sizes accurately. This dual ballotini method was used to assess whether fish ate earlier, later or during both halves of the meal and showed that individual fish feeding patterns were similar across two repeated meals. The method was applied to Chinook salmon (Oncorhynchus tshawytscha), a premium farmed salmonid, to determine the relationship between feed conversion ratio (FCR) and the timing of feeding. Results showed that fish that ate smaller amounts of feed ate most of their meal at the end of the meal. There was no significant difference in when feed efficient or feed inefficient fish ate within the meal but, at the first dual ballotini assessment, there was a relationship between FCR and the timing of feeding where more efficient fish ate later in the meal. However, this relationship was absent at the second time point. Despite this, the dual ballotini method is a promising and versatile alternative method for the characterisation of fish feeding behaviours and can be applied under a range of conditions including higher rearing densities.

Influence of foaming-induced crystallization behavior on the structure of poly(butylene adipate-co-terephthalate) supercritical foamed beads

The crystallization behavior during foaming directly affects the foaming properties. For crystalline polymers, there is no consensus on the influence of the crystallization behavior during foaming process on the stabilization of the cell structure. In this work, PBAT foamed bead and unfoamed pellets were prepared by controlling the saturated temperatures in supercritical CO2, soaking step (one or two) and the depressurization rate, respectively. Double melting peaks were observed in the DSC curve of supercritical CO2 foamed PBAT beads. By comparing the outgassing rates we find that the stretching-induced crystallization caused by the rapid expansion of the gas during foaming plays an important role in the stabilization of the cells. Although the crystalline perfection or crystal size at this time is much smaller than that of the crystalline grains formed during static cooling, the rapid crystallization is effective in stabilizing the cell structure of the foamed pores. Compared to normal supercritical foaming processes, the two-step foaming process of soaking CO2 at high temperatures followed by foaming at low temperatures results in an increase in cell size and expansion ratio. At high temperatures, more CO2 diffuses into the PBAT pellets, increasing the instantaneous gas concentration in the pellets for foaming, and the rapid stretching produces stretching-induced crystallization that raises the average size of the cells, further increasing the expansion multiplicity of individual cells. The average cell size of foam beads rises from 37.8 to 48.8 µm and the expansion ratio also increases to 8.6 with saturated temperature increasing form 95 to 105°C. The two-step soaking foaming method is a more efficient way of manufacturing industrial foamed beads, allowing for the preparation of better foam beads at low temperatures.

PREPARATION AND EVALUATION OF COLON-SPECIFIC PROBIOTIC DELIVERY SYSTEM: SACCHAROMYCES BOULARDII

Probiotics are beneficial microbes that have a beneficial effect on humans as well as animals. Despite their advantages, probiotics face viability challenges during storage and while passing through the upper gastrointestinal tract. This study was designed to develop an encapsulated system of Saccharomyces boulardii (SB) probiotics to overcome challenges with oral administration and develop a colon-targeted delivery system. Pectin and sodium carboxy methyl cellulose encapsulated microbeads of probiotics: polymer ratio (1:1, 1:2, and 1:3) were prepared using the ionotropic gelation technique and then coated with Eudragit® S 100 and cellulose acetate phthalate. They were then evaluated for efficacy and compared for bead size, flow properties, entrapment efficiency, percent yield, swelling index, mucoadhesive ness, in vitro release and viability of probiotics. The microencapsulated probiotics showed higher viability in the colon as compared to gastric and intestinal environments. Hence, microencapsulation is a potential delivery system for the administration of viable probiotics

Development of red mud-modified geopolymer coating with radiative cooling effect for footway application

Radiative cooling coating technology is gaining increasing attention in the context of mitigating urban heat island and tackling global climate change. This paper is concerned with the development of an inorganic geopolymer-based radiative cooling coating using red mud, incorporating varying sizes of TiO2 and hollow glass beads. The developed colored coating demonstrates its radiative cooling capability in reducing the surface temperature by harnessing the potential of red mud. The physico-chemical properties, surface morphology, and element distribution of the coating were characterized by XRD, FTIR, TG-DAT, SEM and EDS. The coating exhibited lower UV (0.0844) and visible reflectance (0.5275) but high NIR reflectance (0.7536), as well as high infrared emissivity of 0.9455, enabling a red color with a CIE value of L* = 74.56, a* = 9.55, and b* = 11.98, and a maximum temperature reduction of 7.3 °C under the climate of Hong Kong. Additionally, the skid resistance, abrasive resistance and adhesion strength of the proposed coating could meet the requirements of standards, indicating a great potential for footway applications.

Optical polarization studies of latex beads in aqueous solution: An analog for radar scattering in icy regolith

This study presents low phase angle 0°–5° measurements of polarimetric properties of icy planetary regolith analog materials acquired using the custom-built Multi-Axis- Goniometer-Instrument (MAGI). We present same sense (SC), and opposite sense (OC) backscatter circular polarization coefficients, circular polarization ratio (CPR), and degree linear polarization (DLP) of spherical latex (non-dye) beads of varying sizes and volume concentrations (v/v) in aqueous solutions (λ=0.8μm) in water. We also present measurements of alumina powder in air at λ=1.064μm. Measurements showed that at a low incidence angle (i=0°), backscatter is dominated by surface specular single-bounce scattering, that hides other scattering processes. At high (i=15°) incidence angle, surface single-bounce surface scattering becomes negligible, allowing for the detection of diffuse, dihedral (multiple bounces) scattering. We find that classical Mie alumina particles (2.1μm,4.0μm) enhance subsurface scattering due to a larger void space relative to larger Mie particles (30μm), that cause the radar signal to scatter forward off small imperfections, maintaining the polarization properties of the signal and generating high >1CPR. Latex beads, representing impurities, demonstrate the impact of isotropic and anisotropic scattering on radar signatures. This study also found that the scattering medium’s anisotropy correlates to the size of the beads, while the void space of the medium inversely correlates with the bead size and the volume concentration (v/v) of the beads. Rayleigh beads, due to isotropic scattering from the reduced scattering cross-section and higher transparency relative to larger impurities, generate subsurface single bounce scattering from the sample platform, producing OC≫SC and a low (<0.5)CPR across all v/v. Rayleigh impurities in transparent water-ice simulate single bounce scattering from underlying layers. Conversely, classical and large Mie beads generate anisotropic scattering that intensifies scattering in the forward direction with high CPR, inversely proportional to the volume concentration. This study aids in interpreting radar observations of icy bodies in the solar system, providing insights into the interplay between radar waves and icy regolith compositions.

Signatures of microstructure in gradient-echo andspin-echo signals.

To determine whether the spatial scale and magnetic susceptibility of microstructure can be evaluated robustly from the decay of gradient-echo and spin-echo signals. Gradient-echo and spin-echo images were acquired from suspensions of spherical polystyrene microbeads of 10, 20, and 40 μm nominal diameter. The sizes of the beads and their magnetic susceptibility relative to the medium were estimated from the signal decay curves, using a lookup table generated from Monte Carlo simulations and an analytic model based on the Gaussian phase approximation. Fitting Monte Carlo predictions to spin-echo data yielded acceptable estimates of microstructural parameters for the 20 and 40 μm microbeads. Using gradient-echo data, the Monte Carlo lookup table provided satisfactory parameter estimates for the 20 μm beads but unstable results for the diameter of the largest beads. Neither spin-echo nor gradient-echo data allowed accurate parameter estimation for the smallest beads. The analytic model performed poorly over all bead sizes. Microstructural sources of magnetic susceptibility produce distinctive non-exponential signatures in the decay of gradient-echo and spin-echo signals. However, inverting the problem to extract microstructural parameters from the signals is nontrivial and, in certain regimes, ill-conditioned. For microstructure with small characteristic length scales, parameter estimation is hampered by the difficulty of acquiring accurate data at very short echo times. For microstructure with large characteristic lengths, the gradient-echo signal approaches the static-dephasing regime, where it becomes insensitive to size. Applicability of the analytic model was further limited by failure of the Gaussian phase approximation for all but the smallest beads.

Impact of drug compounds mechanical/deformation properties on the preparation of nano- and microsuspensions

The preparation of nano- and microsuspensions used for long-acting injectables include several advantages, where the ability to control the particle sizes of a drug compound, e.g., wet bead media milling, to obtain a desired release rate, has shown to be highly critical. Limiting factors, making the formulation screening process time-consuming, are both the grindability of a compound to obtain the desired particle size profile as well as the addition of a suitable stabilizer at a sufficient concentration to secure a long-term physical stability. Hence, the deformation properties of three different model compounds (i.e., cinnarizine, haloperidol, and indomethacin) were investigated in the present study by quantifying fragmentation after tableting followed by the preparation of nano- and microsuspensions with two different stabilizers (polysorbate 20 and poloxamer 188) and concentrations (1, 2, or 4%), as well as bead size (ø 0.5 or 1.0 mm), during processing. It was found that cinnarizine had brittle properties, haloperidol predominantly plastic properties, and indomethacin elastic properties. Distinct particle size profiles, after milling by the dual centrifugation approach, were achieved for the three model compounds, when prepared under the same manufacturing conditions. It was possible to obtain decreased sizes of cinnarizine particles, whereas the grindability for haloperidol was more restricted due to its plastic properties. The study further showed that higher concentrations of poloxamer 188 were needed to obtain smaller sizes of particles when compared to polysorbate 20. Short-term stability studies showed an increase in sizes of particles over 49 days stored at elevated temperatures, especially for indomethacin suspensions stabilized with the highest polysorbate 20 concentration, due to increased solubility from the stabilizer vehicle as confirmed by a solubility study. Sizes of haloperidol particles remained relatively stable when stabilized with the highest concentration of polysorbate 20, even with increased solubility, indicating a higher physical stability as compared to cinnarizine and indomethacin.