Aggregation Of Small Particles Research Articles

Microbially-mediated reductive dissolution of Fe-bearing minerals during freeze-thaw cycles

Constraining the role of microbes in the structural iron (Fe) reduction of iron-bearing minerals improves our understanding of sediments and ice sheets as a source of dissolved Fe (dFe) to the oceans. However, bio-mediated structural Fe-reduction has yet to be studied in cryospheric environments. Here, we show that the Fe reducing psychrophile bacterium Shewanella vesiculosa, isolated from sea ice in Antarctica, reduced structural Fe in nontronite (NAu-2) and maghemite (γ-Fe2O3), common mineral phases in glacial ice, and marine sediments in Antarctica, during two freeze–thaw cycles (−10 °C to +15 °C), resulting in the release of dFe. The modification of turbostratically disordered nontronite (ferric iron dominant phase) to discrete ordered illite-like structure (ferrous iron dominant phase), and the aggregation of altered small maghemite particles with neoformation of vivianite (Fe3(PO4)2·nH2O) indicated the microbially induced reductive dissolution of nontronite and maghemite, respectively. The biotic Fe-reduction gradually decreased and ceased as the temperature approached freezing (−8 °C), however the rection reactivated in the thawing cycle (−7 to +15 °C). No discernable biotic Fe-reduction was measured for either mineral under freezing conditions, suggesting that temperature limits the activity of the microbes. Further, and regardless of temperatures during two freeze–thaw cycles, Fe-reduction was not observed in abiotic control. Overall, these results highlight the importance of microbially induced Fe reduction during seasonal freeze–thaw cycles of ice and sediments in continuous supplying bioavailable dFe to cryospheric environments and the often Fe-limited polar oceans.

Comparative Study and Evaluation of Sediment Deposition and Migration Characteristics of New Sustainable Filter Media in Micro-Irrigation Sand Filters

The quartz sand filter medium used in micro-irrigation media filters has the disadvantages of short filtration cycle, surface filtration, and mining pollution. Selecting resources as new filter media is essential to improve the performance of the media filter and boost sustainable development. In this study, the traditional quartz sand filter medium and two new filter media were selected, and their corresponding filtration performances were comparatively studied. The influence of the type, particle size, and height of the filter medium on filtration performance was evaluated. The sediment content and distribution based on the size of particles in quartz sand, crushed glass, and glass bead filter layers was measured and analyzed. The hydraulic performance of different filter columns was analyzed. The results showed that for a given particle size, quartz sand exhibits the best sediment retention ability. This promoted the aggregation of small sediment particles into larger ones, whereas the crushed glass and bead glass filter layers promoted the splitting of large sediment particles into smaller ones, which enabled the reduction of blockage during the micro-irrigation process. The filtration rate of the quartz sand filter column exhibited the least fluctuation relative to crushed glass and glass bead filter media, and the pressure in each column exhibited a linear incremental change. In summary, glass microbeads are not suitable as filter material, crushed glass is suitable for general micro-irrigation systems, and quartz sand is suitable for micro-irrigation systems with elaborate filtration requirements. The findings of this study can provide theoretical guidance for the selection of the micro-irrigation filter material.

Novel core-shell microcapsules incorporating macro/micronutrients in PVA/starch matrix

Enhanced efficiency fertilizers (EEFs) have been widely used due to their ability to meet crop nutritional needs and reduce the main problem of leaching. In this work, we compared the effects of spray-dryer microspheres and microcapsules on nutrient encapsulation and identified the spheres and core-shell structures by fluorescence microscopy using Rhodamine B (RB) as the fluorescent material. The microsphere matrix was based on starch, and the microcapsules consisted of starch as the core and poly (vinyl alcohol) as the shell. The fluorescent images confirmed that the RB was incorporated into the starch, as the overlap of fluorescence and brightfield images covered the entire area for microspheres and only the core for microcapsules. Microspheres exhibited an irregular and non-spherical morphology, whereas microcapsules presented a spherical shape with a smooth and homogeneous surface featuring small aggregated particles. The microparticle structures remained unchanged even after incorporating KNO3, Fe, Cu, and Mn. Thermal analysis indicated lower initial mass loss temperatures for the microcapsules, suggesting polymer interactions during drying and formation. FTIR further supported this, which revealed structural changes and partial oxidation during drying, contributing to reduced thermodegradation. Notably, micronutrient-based microcapsules demonstrated a significantly lower burst release than macro/micronutrient-based microcapsules and micronutrient-based microspheres. Fe and Cu were released most rapidly from microspheres in the first hour, reaching 84.2% and 79.4%, respectively. In contrast, macro/micronutrient-based microcapsules released 66.1% and 67.7%, while micronutrient-based microcapsules released 53.1% and 61.5%. As for Mn, macro/micronutrient-based microcapsules exhibited the highest initial release at 72.4%, followed by micronutrient-based microcapsules at 62.2%, with microspheres releasing at 55.8%. Additionally, the Peppas-Sahlin model provided the best fit, indicating diffusional and polymer relaxation contributions. The morphology, release, and kinetics behaviors confirmed that the core-shell prolonged the nutrient release by reducing the initial burst release, thanks to the diffusion barrier provided by the PVA layer.

Fabrication of 5-fluorouracil loaded multi-responsive molecularly imprinted poly (NVCL-co-MAA) coated black titanium dioxide nanocomposite as a chemo-photodynamic therapy agent

TiO2 nanoparticles (NPs) are commonly used in cancer photodynamic therapy due to their ultraviolet light–triggered properties. In this study, a molecularly imprinted polymer (MIP)-coated black TiO2 (b-TiO2) nanocomposites (NCs) were synthesized using free radical polymerization of thermosensitive N-vinyl caprolactam and pH-sensitive methacrylic acid functional monomers on the surface of b-TiO2 NPs. B-TiO2 NPs were prepared using calcination of as-synthesized white TiO2 NPs (w-TiO2) at high temperatures. The MIP layer was in-situ deposited on surface-activated b-TiO2 NPs with azobisisobutyronitrile as an initiator and uracil as a pseudo-template molecule of 5-Fluorouracil (5-FU). The samples were characterized using FTIR, NIR, XRD, DLS, TEM, BET and TGA analyses. The average crystallite sizes of w-TiO2, b-TiO2 NPs and the NCs were determined through Sharer's equation as 6.8, 10.36 and 12.61 nm, respectively, which were smaller than those obtained by DLS (7.5, 115 and 130.6 nm, respectively), indicating the aggregation of small particles during calcination at high temperatures. The equilibrium adsorption capacity of NCs and non-imprinted NCs with specific areas of 14.80 m2.g−1 and 7.611 m2.g−1, respectively, toward 5-FU was determined to be 80 and 25 mg.g−1, respectively, indicating that the imprinting process is highly efficient. Higher cumulative drug released in pH 5.5 and 41 ºC confirmed the remarkable potential of NCs as a pH/temperature-responsive delivery vehicle. Moreover, the NCs demonstrated enhanced photothermal/photodynamic and low hemolytic activity (< 5%) compared to b-TiO2 NPs. The findings indicate that NCs showed excellent potential for combining stimuli-responsive chemotherapy with photothermal/photodynamic therapy for melanoma treatment.

Photocatalytic Degradation of Polyethylene Plastics Using MgAl2O4 Nanoparticles Prepared by Solid State Method

In this study, MgAl2O4 nanoparticles with different calcination times were synthesized for photocatalytic applications. Different analyses techniques such as XRD, SEM, EDX, UV-visible, and FTIR were performed to investigate the structural, chemical, optical, and mor-phological properties of the synthesized nanoparticles. XRD analysis revealed the formation MgAl2O4 spinel structure. UV-Visible measurements indicate that MgAl2O4-2 nanoparticles had a narrower energy gap compared to MgAl2O4-1 and MgAl2O4-3. Results of SEM analysis revealed that the synthesized MgAl2O4 nanoparticles consist of small aggregated particles with (40-60 nm) particles size. EDX measurements con-firmed the formation of MgAl2O4 nanoparticles without any impurities. The photocatalytic performance was evaluated by the photodegradation of polyethylene plastics using MgAl2O4 nanoparticles under UV irradiation. The FT-IR measurements before and after the degradation of polyethylene plastics confirm the formation of new functional groups as a result of photodegradation processes.

Sonophotocatalytic degradation of Rhodamine B dye on MgWO4 crystals modified with AgNPs

In recent years, environmental problems caused by organic pollutants, especially industrial organic dyes, have caused severe environmental issues because they are potentially toxic and non-biodegradable carcinogens. Therefore, in this work, the magnesium tungstate (MgWO4) crystals were synthesized by the polymeric precursor method, followed by heat treatment at 900 °C for 2 h. Then, the obtained crystals were modified with silver nanoparticles (AgNPs) by the photoreduction method using silver nitrate solutions at ratios (m/m%) of 0.5%, 2%, and 4%. X-ray diffraction patterns and Rietveld refinement confirmed the presence of MgWO4 crystals with a wolframite-type monoclinic structure, emphasizing that the modification did not promote structural changes, only superficial ones. Raman and Fourier-transform infrared spectroscopies showed twenty-four active vibrational modes overall, seventeen active Raman modes, and seven IR-active modes. X-ray photoelectron spectroscopy (XPS) identified the peaks related to Mg, W, and O elements in all samples, and ascribed to Ag in the modified samples. In addition, field emission scanning electron microscopy (FE-SEM) images showed that both materials present a set of small aggregated particles with irregular shapes. Moreover, the UV–Vis absorption spectra showed a shift of the maximum band to a higher wavelength value from the modification with 2% and 4% of AgNPs with direct forbidden band energy between 3.87 and 4.00 eV. The crystals modified with 2% AgNPs present improved the catalytic properties that pristine MgWO4 crystals since they showed the best sonophotocatalytic (SPC) activity with the 92% degradation rate of Rhodamine B (RhB) dye in 240 min. Finally, we demonstrate for the first time that SPC activity in these crystals enables 74% RhB degradation even after four reuse cycles, while the radical scavengers assays indicated that holes (h) and hydroxyl (OH) radicals are the main ones responsible for the chemical reactions to RhB dye degradation.

Out of the blue: the independent activity of sulfur-oxidizers and diatoms mediate the sudden color shift of a tropical river

BackgroundRío Celeste (“Sky-Blue River”) is a river located in the Tenorio National Park (Costa Rica) that has become an important hotspot for eco-tourism due to its striking sky-blue color. A previous study indicated that this color is not caused by dissolved chemical species, but by formation of light-scattering aluminosilicate particles at the mixing point of two colorless streams, the acidic Quebrada Agria and the neutral Río Buenavista.ResultsWe now present microbiological information on Río Celeste and its two tributaries, as well as a more detailed characterization of the particles that occur at the mixing point. Our results overturn the previous belief that the light scattering particles are formed by the aggregation of smaller particles coming from Río Buenavista, and rather point to chemical formation of hydroxyaluminosilicate colloids when Quebrada Agria is partially neutralized by Río Buenavista, which also contributes silica to the reaction. The process is mediated by the activities of different microorganisms in both streams. In Quebrada Agria, sulfur-oxidizing bacteria generate an acidic environment, which in turn cause dissolution and mobilization of aluminum and other metals. In Río Buenavista, the growth of diatoms transforms dissolved silicon into colloidal biogenic forms which may facilitate particle precipitation.ConclusionsWe show how the sky-blue color of Río Celeste arises from the tight interaction between chemical and biological processes, in what constitutes a textbook example of emergent behavior in environmental microbiology.

Biogeofilter with Hydrothermal Treated Stevensite Clay and Laccase Enzymes for Retention and Degradation of Tetracycline

The concentration of antibiotics in surface water is an issue of high concern. The present study aims to manufacture and evaluate a biogeofilter, with stevensite clay and enzymes immobilized on it, for the adsorption and degradation of tetracycline-based antibiotics. To retain the small particle aggregates of the clay in the filter, a hydrothermal treatment was applied to the stevensite, prior to compaction in pellets and its insertion into a cylindric cell, mixed with sand. The structure of the pellets avoids the loss of the clay material during the fluid transport through the porous medium. Several temperature treatments were applied to the pellets, but the treatment at 300 °C was revealed as the best option. Laccase enzymes were immobilized on the stevensite surface. Reactive transport experiments of tetracycline solutions were performed through the transport cells. The biogeofilter has a relevant adsorption capacity with a significant degradation factor. By modelling with STANMOD software, the hydrodynamic characteristics of the transport were determined and, therefore, the behaviour of a large-scale filter and transports of low tetracycline concentrations could be predicted. The results obtained are promising for irrigation systems at medium scale, as well as for the perspective of wastewater treatment plants at large scale.

Thermal Swing Reduction-Oxidation of Me(Ba, Ca, or Mg)SrCoCu Perovskites for Oxygen Separation from Air

The climate change impact associated with greenhouse gas emissions is a major global concern. This work investigates perovskite compounds for oxygen separation from air to supply oxygen to oxyfuel energy systems to abate these significant environmental impacts. The perovskites studied were Me0.5Sr0.5Co0.8Cu0.2O3−δ (MeSCC) where the A-site substitution was carried out by four different cations (Me = Ca, Mg, Sr, or Ba). SEM analysis showed the formation of small particle (&lt;1 µm) aggregates with varying morphological features. XRD analysis confirmed that all compounds were perovskites with a hexagonal phase. Under reduction and oxidation reactions (redox), Ba and Ca substitutions resulted in the highest and lowest oxygen release, respectively. In terms of real application for oxygen separation from air, Ba substitution as BaSCC proved to be preferable due to short temperature cycles for the uptake and release of oxygen of 134 °C, contrary to Ca substitution with long and undesirable temperature cycles of 237 °C. As a result, a small air separation unit of 0.66 m3, containing 1000 kg of BaSCC, can produce 18.5 ton y−1 of pure oxygen by using a conservative heating rate of 1 °C min−1. By increasing the heating rate by a further 1 °C min−1, the oxygen production almost doubled by 16.7 ton y−1. These results strongly suggest the major advantages of short thermal cycles as novel designs for air separation. BaSCC was stable under 22 thermal cycles, and coupled with oxygen production, demonstrates the potential of this technology for oxyfuel energy systems to reduce the emission of greenhouse gases.

Quantifying the relative contribution of driving factors to the transformation of bauxite residue into a plant growth substrate

The vast stock and increasing amount of bauxite residue with high alkalinity, low nutrient and poor structure poses a significant challenge to plant growth. Although additives have been recognized to have obvious effects on the transformation of bauxite residue to a soil-like media for plant growth, a clear understanding of the quantitative contribution of physicochemical properties to plant growth is missing. This study aimed to discuss the portrayed role and contributions of additives mediated alkalinity, nutrient, and aggregates component in the significant factors of aggregate structure formation and corresponding plants seed germination in bauxite residue. The regulation of pH and total alkalinity in bauxite residue depends on inorganic additives, while for ESP and nutrients, nitrohumic acid and vinegar residue are better than inorganic and citric acid. The silt-clay fraction and microaggregate increased from 35.1% and 25.6% to 40.8% and 31.9% within citric acid addition, respectively, while macroaggregate increased from 39.2% to 49.9% within nitrohumic acid application, indicating citric acid may be more involved in the formation of the fundamental building units of organo-mineral associations in bauxite residue, while nitrohumic acid and vinegar residue may play an important role in continuous aggregation of small particles. For aggregates component, calcium in silt-clay fraction had the largest explanatory power in aggregate stability and germination rate (R2 = 65.6%), followed by Al in 0.25–2 mm size fraction (R2 = 11.1%), while organic complex Fe oxides and Mg in microaggregate explained little variance (R2 = 3.89% and R2 = 1.25%), demonstrating Ca, Fe, and Mg contributed greatly to the formation of microaggregate, while Si and Al contributed greatly to the formation of large aggregate. Besides the dominant role of aggregates component, aggregate stability related to mean weight diameter, large macroaggregates, fractal dimension, and silt-clay fraction plays a more critical role in seed germination.

Beamline setup for in situ measurements of particles in turbulent spray flames using small angle X-ray scattering

The particle formation in spray flame synthesis (SFS) is a fast and complex process involving many sub-steps that may happen simultaneously. To investigate the mechanisms that typically lead to small aggregated primary particles, a sophisticated technique for in situ measurements in the flame is necessary to provide information about primary particles and the aggregates as well. This work describes the development of an in situ measurement setup using small angle X-ray scattering (SAXS) to investigate the entire particle formation mechanism of zirconia nanoparticles in and above a turbulent spray flame. In preparation for the in situ measurements, a beamline for single crystal diffractometry at Karlsruhe Research Accelerator (KARA) was adapted for low scattering SAXS experiments including optimizations of the optics and measurement protocol. As a result, a significant dependence of scattering intensity was detected as a function of the height above the burner. A detailed analysis of the SAXS data and comparison with TEM images allow insights into the primary particle growth, the development of fractal properties and the aggregation process.

Ice microphysical processes in the dendritic growth layer: a statistical analysis combining multi-frequency and polarimetric Doppler cloud radar observations

Abstract. The dendritic growth layer (DGL), defined as the temperature region between −20 and −10 ∘C, plays an important role for ice depositional growth, aggregation and potentially secondary ice processes. The DGL has been found in the past to exhibit specific observational signatures in polarimetric and vertically pointing radar observations. However, consistent conclusions about their physical interpretation have often not been reached. In this study, we exploit a unique 3-months dataset of mid-latitude winter clouds observed with vertically pointing triple-frequency (X-, Ka-, W-band) and polarimetric W-band Doppler radars. In addition to standard radar moments, we also analyse the multi-wavelength and polarimetric Doppler spectra. New variables, such as the maximum of the spectral differential reflectivity (ZDR) (sZDRmax), allows us to analyse the ZDR signal of asymmetric ice particles independent of the presence of low ZDR producing aggregates. This unique dataset enables us to investigate correlations between enhanced aggregation and evolution of small ice particles in the DGL. For this, the multi-frequency observations are used to classify all profiles according to their maximum average aggregate size within the DGL. The strong correlation between aggregate class and specific differential phase shift (KDP) confirms the expected link between ice particle concentration and aggregation. Interestingly, no correlation between aggregation class and sZDRmax is visible. This indicates that aggregation is rather independent of the aspect ratio and density of ice crystals. A distinct reduction of mean Doppler velocity in the DGL is found to be strongest for cases with largest aggregate sizes. Analyses of spectral edge velocities suggest that the reduction is the combined result of the formation of new ice particles with low fall velocity and a weak updraft. It appears most likely that this updraft is the result of latent heat released by enhanced depositional growth. Clearly, the strongest correlations of aggregate class with other variables are found inside the DGL. Surprisingly, no correlation between aggregate class and concentration or aspect ratio of particles falling from above into the DGL could be found. Only a weak correlation between the mean particle size falling into the DGL and maximum aggregate size within the DGL is apparent. In addition to the correlation analysis, the dataset also allows study of the evolution of radar variables as a function of temperature. We find the ice particle concentration continuously increasing from −18 ∘C towards the bottom of the DGL. Aggregation increases more rapidly from −15 ∘C towards warmer temperatures. Surprisingly, KDP and sZDRmax are not reduced by the intensifying aggregation below −15 ∘C but rather reach their maximum values in the lower half of the DGL. Also below the DGL, KDP and sZDRmax remain enhanced until −4 ∘C. Only there, additional aggregation appears to deplete ice crystals and therefore reduce KDP and sZDRmax. The simultaneous increase of aggregation and particle concentration inside the DGL necessitates a source mechanism for new ice crystals. As primary ice nucleation is expected to decrease towards warmer temperatures, secondary ice processes are a likely explanation for the increase in ice particle concentration. Previous laboratory experiments strongly point towards ice collisional fragmentation as a possible mechanism for new particle generation. The presence of an updraft in the temperature region of maximum depositional growth might also suggest an important positive feedback mechanism between ice microphysics and dynamics which might further enhance ice particle growth in the DGL.

Long-term immobilization of cadmium and lead with biochar in frozen-thawed soils of farmland in China

The problem of potentially toxic elements (PTEs) in farmland is a key issue in global pollution prevention and control and has an important impact on environmental safety, human health, and sustainable agricultural development. Based on the climate background of high–latitude cold regions, this study simulated freeze–thaw cycles through indoor tests. Different initial conditions, such as biochar application rates (0%, 1%, 2%) and different initial soil moisture contents (15%, 20%, 25%), were set to explore the morphological changes in cadmium (Cd) and lead (Pb) in soil and the response relationship to the changes in soil physicochemical properties. The results indicate that soil pH decreases during freeze–thaw cycles, and soil alkalinity increases with increasing biochar content. Freeze–thaw cycles caused the total amount of PTEs to have a U–shaped distribution, and the amount of PTEs in the soluble (SOL) and reducible (RED) fraction increased by 0.28–56.19%. Biochar reduced the amount of Cd and Pb migration in the soil, and an increase in soil moisture content reduced the availability of Cd and Pb in the soil. Freezing and thawing damaged the soil structure, and biochar reduced the fractionation of small particle aggregates by enhancing the stability of soil aggregates, thereby reducing the soil's ability to adsorb Cd and Pb. In summary, for farmland soil remediation and pollution control, the application of biochar has a certain ability to optimize soil properties. Considering the distribution of PTEs in the soil and the physicochemical properties of the soil, the application of 1% biochar to soil with a 20% moisture content is optimal for regulating seasonally frozen soil remediation.

Packed media radiative-transfer modeling with Gaussian particles: Application to spectra of icy regolith of Saturnian satellites

The radiative transfer theory with packed media correction (RTT-PM) is a balanced, physically rigorous, and practical light scattering model that is suitable for modeling reflectance and similar spectra of densely packed particulate media. The static structure factor correction to the classical radiative transfer solution and actualization of fundamental particles of media with spheres or aggregates are key properties of this model that ensure both physical rigor and practical efficiency. We improved upon the assumptions in the RTT-PM method by incorporating irregularly shaped Gaussian particles into its scheme. This incorporation of Gaussian particles is a notable advancement for applications of the RTT-PM method to planetary surfaces that often are layers of irregularly shaped particles. With the Gaussian particle RTT-PM method, we modeled spectra of Saturnian moons Dione, Rhea, and Tethys observed with the Cassini Visual and Infrared Mapping Spectrometer (VIMS), assuming pure water ice composition. For Rhea and Tethys, the Gaussian particle RTT-PM technique modeled VIMS spectra better than models with spherical or aggregate particles, strengthening prior suggestion that particles on Rhea and Tethys are solid, non-spherical particles. Dione's spectra were best modeled not with Gaussian particles but rather with an aggregate of 128 monomers. This makes Dione's icy regolith different from that on Rhea and Tethys. Prior studies have indicated that the cause for the difference might arise from the presence of surface macrostructures or absorbing materials on Dione, but according to our modeling results, increased multiple scattering from small fluffy aggregate particles is an alternative explanation.

Scaling limits for planar aggregation with subcritical fluctuations

We study scaling limits of a family of planar random growth processes in which clusters grow by the successive aggregation of small particles. In these models, clusters are encoded as a composition of conformal maps and the location of each successive particle is distributed according to the density of harmonic measure on the cluster boundary, raised to some power. We show that, when this power lies within a particular range, the macroscopic shape of the cluster converges to a disk, but that as the power approaches the edge of this range the fluctuations approach a critical point, which is a limit of stability. The methodology developed in this paper provides a blueprint for analysing more general random growth models, such as the Hastings-Levitov family.

Рharmaceutical-technological Study of Adsorbed Liquid Plant Extract of Antimicrobial Activity

Introduction. The use of a combined herbal extract of chamomile flowers, calendula flowers and yarrow herb (patent RU 1 561 262 C) can be effective against various microbial strains, including those causing inflammatory diseases of the oral cavity. The article presents the results of a comparative pharmaceutical and technological study of an adsorbed liquid plant extract on sorbents of various nature for subsequent introduction into the composition of orodispersible tablets. Aim. To select the optimal sorbent of liquid plant extract of chamomile flowers, calendula and yarrow herb ensuring the suitability of the active pharmaceutical ingredient for direct compression, by analyzing using the SeDeM expert system method. Materials and methods. Active pharmaceutical ingredient was adsorbed on organic (microcrystalline celluloses of various brands) and inorganic (colloidal silicon dioxide of various brands) sorbents, a liquid combined plant extract of anti-inflammatory and antibacterial action of chamomile flowers, calendula flowers and yarrow herb. Pharmaceutical-technological analysis included the study of such technological parameters as: Bulk Density ( Da = m / Va ), Tapped Density ( Dc = m / Vc ), Inter-particle Porosity (Ie = ( Dc – Da)/(Dc · Da )), Carr index (IC = (Dc – Da )/( Dc · 100)), Cohesion Index (Icd), Hausner Index ratio (IH = Dc / Da ), Angle of Repose ( Tg α = h / r ), Powder Flow ( t ), Loss of Drying (%LoD), Hygroscopicity ( %H), Particles &lt;50 μm (%Pf), Homogeneity Index ( I Θ = Fm /100 + ∆ Fmn a ). Results and discussion. A comprehensive pharmaceutical-technological study of sorbents of liquid plant extract before and after adsorption was carried out, the results of which were processed and presented by the SeDeM expert system method. It was found that the adsorption of the extract has a positive effect on the Dimension ( ID = ( Da · Dc )/2) of all studied sorbents which may be related to change in the fractional composition due to the aggregation of small particles during adsorption and destruction of large ones when sifting the finished mixtures through a sieve with a mesh diameter of 200 μm (recommended insoluble particle size for use in the oral cavity). A negative effect on the Stability (IS = (%LoD · %H)/2 ) was also recorded for all samples, regardless of their nature, which is probably explained by residual moisture after drying and high hygroscopicity of adsorbed plant bioactive substances. Changes in the Compressibility (IC = (Ie · IC · Icd)/3), Flowability (IF = (IH · α · t )/3) and Dosage (IDos = (%Pf · I Θ )/2) are individual. Conclusion. The SeDeM expert system method makes it possible to characterize bulk materials from the point of view of suitability for direct compression, to establish the factors that need to be primarily corrected by the introduction of auxiliary substances. As a result of the conducted studies, Aeroperl 300 (inorganic sorbent) and Pharmacel 112 (organic sorbent) can be recommended for the introduction of liquid plant extract of chamomile flowers, calendula flowers and yarrow herb into the composition of orodispersible tablets.

A continuum model for the segregation of bidisperse particles in a blade mixer

AbstractThe process of blending powders using stirring blades involves complicated granular flows, particle‐scale mechanisms, and blade–particle interactions, which is challenging to predict and control. This article proposes a continuum‐based model for such a process by incorporating the flow rheology, isotropic particle diffusion and the percolation of granular materials. A method combining finite element method (FEM), finite difference method (FDM), and immersed boundary method (IBM) is developed to numerically implement the continuum model and applied to a cylindrical blade mixer. The model well describes the tempo‐spatial distribution of small/large particles in the stirring process, such as the accumulation of small particles in the vicinity of blades. Remarkably, this model can capture the various intricate effects of blade parameters, including the blade rake angle, rotating speeds, filling level, and the friction coefficient of the mixer wall. It is therefore promising for optimizing the blade mixers in industries.

Scattering of Electromagnetic Radiation by Linear Small-Particle Aggregates of Finite Dielectric Cylinders

Scattering of Electromagnetic Radiation by Linear Small-Particle Aggregates of Finite Dielectric Cylinders

Synthesis and flame inhibition efficiency of a novel Fe-based metal complex with phosphorus-containing structure

Owing to the increased depletion risk and cost of phosphate mines, the demand for low phosphorus or ecological phosphorus flame inhibitor is increasing. This study reports an experimental exploration of the combustion inhibition efficiency of bio-based transition metal complex materials containing iron and phosphorus, namely, iron @ phosphorus complex (Fe-PMC). The aim is to develop a new type of flame inhibitor with an iron-phosphorus interaction effect to replace pure phosphorus extinguishing agents. The synthesis of Fe-PMC was characterized by Fourier-transform infrared spectroscopy, X-Ray diffraction, X-ray photoelectron spectroscopy and Scanning electron microscope. The Fe-PMC (ⅰ) is the mesh porous structure connected by the accumulation of small particles, (ⅱ) is an amorphous structure with many binding sites exposed and excellent interface compatibility, (ⅲ) contains no chloride ions. Suppression tests and thermogravimetric measurements indicate that (ⅰ) Fe-PMC has a higher combustion inhibition ability than MIL-53 containing only iron, especially at low concentrations, (ⅱ) Fe-PMC reduces the laminar flame velocity of cellulose, (ⅲ) Fe-PMC greatly reduces flame temperature. The activation energy (E), pre-exponential factor (A) and char yield (Y) of cellulose pyrolysis were determined by kinetic analysis. It concluded that MIL-53 and Fe-PMC produce combustion inhibition mainly in the solid phase. These findings will contribute to the development of a flame inhibitor with low or no phosphorus and better performance.

Properties of Biocomposite Film Based on Whey Protein Isolate Filled with Nanocrystalline Cellulose from Pineapple Crown Leaf.

Among the main bio-based polymer for food packaging materials, whey protein isolate (WPI) is one of the biopolymers that have excellent film-forming properties and are environmentally friendly. This study was performed to analyse the effect of various concentrations of bio-based nanocrystalline cellulose (NCC) extracted from pineapple crown leaf (PCL) on the properties of whey protein isolate (WPI) films using the solution casting technique. Six WPI films were fabricated with different loadings of NCC from 0 to 10 % w/v. The resulting films were characterised based on their mechanical, physical, chemical, and thermal properties. The results show that NCC loadings increased the thickness of the resulting films. The transparency of the films decreased at higher NCC loadings. The moisture content and moisture absorption of the films decreased with the presence of the NCC, being lower at higher NCC loadings. The water solubility of the films decreased from 92.2% for the pure WPI to 65.5% for the one containing 10 % w/v of NCC. The tensile strength of the films peaked at 7% NCC loading with the value of 5.1 MPa. Conversely, the trend of the elongation at break data was the opposite of the tensile strength. Moreover, the addition of NCC produced a slight effect of NCC in FTIR spectra of the WPI films using principal component analysis. NCC loading enhanced the thermal stability of the WPI films, as shown by an increase in the glass transition temperature at higher NCC loadings. Moreover, the morphology of the films turned rougher and more heterogeneous with small particle aggregates in the presence of the NCC. Overall, the addition of NCC enhanced the water barrier and mechanical properties of the WPI films by incorporating the PCL-based NCC as the filler.