Dispersion Type Research Articles

Stability of Co-amorphous Solid Dispersions: Physical and Chemical Aspects

Drug amorphization is one of the major approaches in pharmaceutical sciences to improve the solubility and dissolution rate of poorly water-soluble drugs. Amorphous solid dispersions are widely discussed approach to convert the drug into an amorphous state but due to its high energy state, the system tends to recrystallize upon storage. Co-amorphous system is a single-phase low energy system that falls under the glass solution, a type of solid dispersion. Being low-energy state and single-phase, co-amorphous dispersions are more stable than amorphous solid dispersions. In co-amorphous dispersions, the homogeneous single phase is formed only with low molecular weight co-formers, so the amount of co-former required is relatively low and this reduces the bulk of the system. This aspect of co-amorphous dispersions makes it popular over the amorphous solid dispersions in the area of solid dispersion researchers. This review provides an overview of co-amorphous dispersions and their recent advances. Particularly, this review will discuss various factors (physical and chemical) that affect and provide the stability of the co-amorphous dispersions formulation.

A double perovskite BaCaZrMnO6: synthesis, microstructural dielectric, transport and optical properties

In this communication, synthesis (solid-state reaction) and characterization of a double perovskite BaCaZrMnO6 are reported. The Williamson–Hall method is used to compute average crystallite and micro-lattice strain in the prepared sample after structural analysis with X-Pert High-Score software. The sample's microstructural characteristics were investigated using a scanning electron microscope (SEM), and compositional purity was determined using energy dispersive x-ray spectroscopy (EDX). The Raman spectrum displays all atomic modes of vibration, providing information on phase, polymorphic crystallinity, and molecular interaction, as well as confirming the presence of all constituent elements. The ultraviolet visible spectrum research gives good bandgap energy for several optoelectronic devices. The impedance parameters have been measured using an impedance analyzer in a wide range of frequencies (102–106 Hz) and temperatures from 25 °C to 500 °C. The dielectric versus temperature and frequency analysis validates the Maxwell–Wanger type of dielectric dispersion. The impedance spectroscopy investigation indicates that the sample exhibits a negative temperature coefficient of resistance (NTCR), whereas the modulus analysis verifies a non-Debye type of relaxation process. The results of the ac conductivity research confirm a thermally activated relaxation process. Nyquist plot analysis reveals the NTCR character, which is well supported by Cole–Cole plots. The resistance versus temperature analysis supports the NTC thermistor nature, but the polarization–electric field (P–E) loop analysis reveals the presence of ferroelectric character, making it a strong option for temperature sensors and ferroelectric-related devices.

Experimental investigation on pH and stability of distilled water ethylene glycol mixture with graphene nanoplatelets

An efficient heat transfer medium improves the overall efficiency of the equipment, and the main difficulty is with making well-dispersed nanoparticles in base fluids. The current research is focused to study the effect of different surfactants on nanoparticle dispersion and enhancement through property modifications. The stability and pH value of various surfactants with varying sonication duration were studied and compared with the graphene nanofluids. The graphene nanofluids were prepared by a two-step method by dispersing 0.1 wt% graphene nanoparticles in distilled water and ethylene glycol with a ratio of 70:30. The surfactants namely Cetyltrimethylammonium bromide (CTAB), Polyvinylpyrrolidone (PVP K-30), and Polysorbate 60 (Tween 60) of each 0.1 wt% were used for stabilizing the nanofluids. The duration of the sonication process was set as 60, 90, and 120 min respectively followed by the magnetic stirring for 60 min duration. The stability behavior of nanofluids was studied through visual inspection, UV spectrum, and zeta potential techniques, and the corresponding pH values were measured to correlate with the performance of the heat transfer equipment. The results showed that the dispersion of graphene nanofluids strongly depends on the type and amount of dispersant in the absolute value of zeta potential. Finally, the optimum conditions were found based on the enhanced stability, pH, and sonication time of graphene nanoplatelets in distilled water-ethylene glycol mixture with Polyvinylpyrrolidone (PVP K-30) as a surfactant for the battery thermal management systems (BTMS) in electric vehicles.

On the Cauchy problem for dispersive Burgers type equations

On the Cauchy problem for dispersive Burgers type equations

The Effect of Prosopis juliflora (Fabaceae) on the Physical and Chemical Properties of Coastal Dune Soil in Western Mexico

Vargas-Lomelín, J.G.; Macías-Rodríguez, M.Á.; Zarazúa-Villaseñor, P.; Rodríguez-Zaragoza, F.A.; Neri-Luna, C., and Albuquerque, F., 2023. The effect of Prosopis juliflora (Fabaceae) on the physical and chemical properties of coastal dune soil in western Mexico. Journal of Coastal Research, 39(1), 63–72. Charlotte (North Carolina), ISSN 0749-0208. Prosopis juliflora (Fabaceae) is a dominant legume and potential ecosystem engineer in the dunes of Jalisco, western Mexico. The objective of the present study was to evaluate how P. juliflora modifies soil physical and chemical properties in three coastal dunes that belong to different watersheds. To determine the physical properties of the three sites, soil samples were taken inside the canopy of five P. juliflora trees and five soil samples were taken outside their canopies. The same trees and soil positions regarding the canopy of P. juliflora were considered to determine the chemical properties, but the samples were taken at two different depths. A multidimensional and permutational analysis of variance (PERMANOVA) was performed to evaluate differences in the physical properties among the sites and between the sampling positions relative to the canopy of P. juliflora. This PERMANOVA also evaluated differences among sites, sample depths, and the positions of the samples relative to the P. juliflora canopy. A test of homogeneity of dispersions was performed to determine the data dispersion type, whereas a similarity percentage analysis identified which variables contributed most to the observed differences. A principal coordinate analysis was performed to visualize the differences in the model. The results demonstrated that P. juliflora modified the soil physical properties, specifically the real density, total porosity percentage, and percentages of silt and clay. The soil physical properties also varied significantly among the three sites. In addition, P. juliflora modified the soil chemical properties, increasing the electrical conductivity, pH, and total nitrogen, iron, and available phosphorus content. The results show significant differences between the two soil depths, as well as among sites. Ultimately, this study contributes to understanding of the implications of soil property modifications by plants in coastal dunes, which will give guidelines for managing and conserving these ecosystems.

Characterization of Mediterranean endemics in the Egyptian flora

The Mediterranean Basin is the world’s second richest hotspot, and one of the most important locations on the planet for endemic taxa. However, there is no available up-to-date list of Mediterranean endemics. Available data are frequently insufficient or outdated. Therefore, this study aimed at delimiting the Mediterranean floristic region in Egypt, screening its Mediterranean endemics, and determining their habitats, life forms, flowering periods, dispersal types and phyto-geographical distribution. From a list of 275 Mediterranean endemic taxa in Egypt compiled from literature, this study reduced it to 57 taxa (including species, subspecies and varieties; 20.7%) belonging to 46 genera and 22 families. Fifteen major habitats harbored Mediterranean endemics in Egypt, with coastal dunes (17 taxa = 29.8%) and non-saline depressions (16 taxa = 28.1%) being the most represented. Moreover, the Mareotis (west) subsector was the richest (46 taxa = 80.7%). The largest number of taxa was recorded in North African sub-region (52 taxa = 91.2%), followed by Eastern (levant) sub-region (36 taxa = 63.2%). Therophytes were the most recorded life form, while ballochory was the most represented dispersal type. In conclusion, it is crucial to shed the light on Mediterranean endemics and provide an up-to-date documented database to help future management plan that support their conservation and sustainable use.

The potential of selected plant extracts in anti-acne skincare formulations

Consumer awareness and the desire to reach for cosmetics with natural ingredients are still growing. The active ingredients of plants can reduce acne lesions and skin redness accompanying them. Specialised cosmetic formulations should support Anti-acne products containing therapeutic agents, reducing visible skin inflammation. These products should act simultaneously, ensuring proper skincare due to the content of plant metabolites exhibiting desired biological activity. In this study, the application of a selected plant extract in cosmetic preparations for acne skincare containing selected plant extracts was prepared: Arnica montana flower, Sambucus nigra and Rosmarinus officinalis leaf, Saponaria officinalis root, Aloe barbadensis leaf juice and Silybum marianum seed oil and then their effects were compared. The extracts were applied as active ingredients in face cream, serum and micellar solution forulations. The physicochemical properties (pH value, stability, dispersed phase particle size and type of emulsion) were evaluated; moreover, rheological tests of the samples were carried out, and the skin cleansing ability of the micellar solution was examined. In addition, all the formulations were subject to various tests, which allowed for the evaluation of their organoleptic properties. It was noticed that the used plant raw materials affect the care of the skin with acne tendencies. Both extracts (Arnica montana flower extract and Sambucus nigra extract) were used in the same concentrations in the cosmetics so that differences in results were easy to compare. Importantly, during the consumer tests, the probants discontinued usage of other anti-acne agents normally applied, which allowed for an objective assessment of the effect of the tested extracts on the acne skin. The formulations tested were proven to be effective cosmetics supporting anti-acne therapy.

AutoML-Based Neural Architecture Search for Object Recognition in Satellite Imagery

Advancements in optical satellite hardware and lowered costs for satellite launches raised the high demand for geospatial intelligence. The object recognition problem in multi-spectral satellite imagery carries dataset properties unique to this problem. Perspective distortion, resolution variability, data spectrality, and other features make it difficult for a specific human-invented neural network to perform well on a dispersed type of scenery, ranging data quality, and different objects. UNET, MACU, and other manually designed network architectures deliver high-performance results for accuracy and prediction speed in large objects. However, once trained on different datasets, the performance drops and requires manual recalibration or further configuration testing to adjust the neural network architecture. To solve these issues, AutoML-based techniques can be employed. In this paper, we focus on Neural Architecture Search that is capable of obtaining a well-performing network configuration without human manual intervention. Firstly, we conducted detailed testing on the top four performing neural networks for object recognition in satellite imagery to compare their performance: FastFCN, DeepLabv3, UNET, and MACU. Then we applied and further developed a Neural Architecture Search technique for the best-performing manually designed MACU by optimizing a search space at the artificial neuron cellular level of the network. Several NAS-MACU versions were explored and evaluated. Our developed AutoML process generated a NAS-MACU neural network that produced better performance compared with MACU, especially in a low-information intensity environment. The experimental investigation was performed on our annotated and updated publicly available satellite imagery dataset. We can state that the application of the Neural Architecture Search procedure has the capability to be applied across various datasets and object recognition problems within the remote sensing research field.

Structural, optical, magnetic and dielectric properties of Ag doped Mg nano ferrites prepared by citrate gel auto combustion method

The Silver Substituted Magnesium ferrites with the formula MgAgXFe2-XO4 (where 0 ≤ x ≤ 0.5 by step 0.1) have been prepared through the citrate gel auto combustion method. Prepared samples structural, morphological, electrical, and magnetic properties have been investigated by XRD analysis, FESEM, AC conductivity, and VSM respectively. XRD and FESEM were used to investigate the structural properties of prepared ferrite materials such as average crystalline size, lattice parameter, X-ray density, unit cell volume, and morphology. Crystalline size was measured to be between 25–30 nm. Five Raman active modes (A1g+Eg+3Tg) were observed in the Raman Spectrum, which are expected in the spinal ferrite system. The prepared sample's structure is confirmed by FTIR spectra bands appearing ∼400 and ∼600 cm−1 wave number region indicates that stretching frequency of tetrahedral (A-site) and octahedral (B-site) respectively. The optical band gap energy of the material observed ranged from 3.44 to 3.51 eV. The variation of dielectric properties has been studied with regard to temperature variation as a function of frequency. All the samples dielectric constant decreases with increasing frequency and temperature, which is the nature of ferrites. It obeys the Maxwell-Wagner type of dispersion because of interfacial polarization. The magnetic properties investigated by room temperature VSM, low coercivity values observed indicate that the sample is of soft magnetic nature.

RESEARCHES OF CHANGES OF THE COEFFICIENT OF A FILTRATION OF THE POROUS MEDIA AT THE DIFFERENT TYPES OF FORMATION OF A DEPOSIT. THE THEORETICAL ANALISIS AND PRACTICAL RECOMMENDATIONS FOR CALCULATIONS OF CLEARING FILTERS

On the basis of analogy betweem the laminar flow of a viscous liquid in a tube and a filtration in the porous media which submits to the linear law of resistance Dar-cy the formula for calculation of coefficient of a filtration at the combined form of adjournment of a deposit is obtained. Practical recommendations for a choiсе of theoretical and approximating experimental dependences for different types of formation of a deposit are given.
 Theoretical and applied studies of filtration of heterogeneous ridins in porous mediums with changing powers took away significant development in connection with solutions to the problems of water purification in the form of finely dispersed mineral and columnar particles and speeches. Changes in the power of porous media are observed in the history of various mechanical, physical-chemical and biological processes of mass transfer which are visible on the surface of the particles of the middle (surfase – the slurry type of the settlements of the siege after adsorption), or without the middle in the port channels (volume – the dispersed type of the settlement of the siege).
 With accumulated siege (the process of colmatation), a change in porosity and filtration coefficient is observed, and with inflows (the process of suffocation) – an increase in these important parameters of the porous medium.
 When filtering rich-phase and rich components sieges, it can be settled in a mixed (complex) form, like in plivkovy so in general. In case of filfiltration of rich-phase and rich-component native sediments, it can be settled in mixed (complex) forms – like in smelt, and in general forms. The type of the process of the siege of creation and indicated on the basis of laboratory data. To lie in the nursery area on the surface of the particles of interest, adhesive and sorption power of the particles of the medium, according to the type of encroachment, district, temperature and other char-acteristics of the porous medium and pore waters.

A Study on Aqueous Dispersing of Carbon Black Nanoparticles Surface-Coated with Styrene Maleic Acid (SMA) Copolymer.

Carbon black (CB) particles tend to aggregate in aqueous solutions, and finding an optimum dispersing condition (e.g., selection of the type of dispersant) is one of the important tasks in related industries. In the present study, three types of styrene maleic acid (SMA) copolymer dispersants were synthesized, labeled respectively 'SMA-1000', 'SMA-2000', and 'SMA-3000', which have 1, 2, and 3 styrene groups in their repeating units. Then, asymmetrical flow field-flow fractionation (AsFlFFF) was employed to measure the particle size distributions of the aqueous CB dispersions. For the particle size analysis of the CB dispersions, dynamic light scattering (DLS) showed relatively lower reproducibility than AsFlFFF. AsFlFFF showed that the use of SMA-3000 yielded a CB dispersion with the most uniform particle size distribution. When the SMA-3000 dispersant was used, the particle size tended to increase after 1 h of milling as the milling time increased, probably due to the re-agglomeration of the particles by excessive milling. The particle size distributions from AsFlFFF were consistent with the colorimetric observations. With the SMA-3000 dispersant, the lowest L∗ value was observed after 1 h of milling. The AsFlFFF and colorimetric analyses suggest that a stable CB dispersion can be obtained by either 3-h of milling with the SMA-2000 or 1-h of milling with the SMA-3000.

Cerium modified (BiFeO3)0.5 – (MgTiO3)0.5 ceramics: Structural, microstructural, dielectric, transport and optical properties

In this communication, the synthesis (solid-state reaction) and characterization (structural, dielectric, and optical) of the 0.5BiFeO3-0.5MgTi1-xCexO3 (x = 0, 0.03. 0.06 and 0.1), (BFMTO) ceramics are reported. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic crystal symmetry (#Cmm2) and is well-supported by the results of the tolerance factor. The average crystallite size is about 30 nm. The ratio of average grain size to average crystallite size may be one of the reasons for better dielectric properties in the prepared samples. The microstructural analysis by scanning electron microscopy (SEM) micrograph suggests the presence of uniformly distributed grains through well-defined grain boundaries. The compositional and purity of the samples were studied by energy dispersive x-ray analysis (EDX). The study of the Fourier transform infrared spectroscopy (FTIR) spectrum reveals the presence of all functional groups related to constituent elements in the samples. The analysis of the dielectric properties suggests the presence of the Maxwell-Winger type of dispersion. The study of impedance spectroscopy suggests the fact that how the grains and grain boundaries play an important role in defining the conductivity mechanism and hence prove a non-Debye type of relaxation. The presence of semicircular arcs for x = 0, 0.03, 0.06, and 0.1 ceramics in both Nyquist and Cole-Cole plots reveal a negative temperature coefficient of resistance (NTCR) character. The study of UV visible spectra predicts an energy bandgap in the range of 1.24 to 1.62 eV, which makes the compound a suitable candidate for photovoltaic applications.

Multiple‐Group Joint Modeling of Item Responses, Response Times, and Action Counts with the Conway‐Maxwell‐Poisson Distribution

AbstractMultiple group modeling is one of the methods to address the measurement noninvariance issue. Traditional studies on multiple group modeling have mainly focused on item responses. In computer‐based assessments, joint modeling of response times and action counts with item responses helps estimate the latent speed and action levels in addition to latent ability. These two new data sources can also be used to further address the measurement noninvariance issue. One challenge, however, is to correctly model action counts which can be underdispersed, overdispersed, or equidispersed in real data sets. To address this, we adopted the Conway‐Maxwell‐Poisson distribution that accounts for different types of dispersion in action counts and incorporated it in the multiple group joint modeling of item responses, response times, and action counts. Bayesian Markov Chain Monte Carlo method was used for model parameter estimation. To illustrate an application of the proposed model, an empirical data analysis was conducted using the Programme for International Student Assessment (PISA) 2015 collaborative problem‐solving items where potential measurement noninvariance issue existed between gender groups. Results indicated that Conway‐Maxwell‐Poisson model yielded better model fit than alternative count data models such as negative binomial and Poisson models. In addition, response times and action counts provided further information on performance differences between groups.

Structural and physical properties of spray-dried fish oil microcapsules via pea protein isolate based emulsification or complex coacervation with sugar beet pectin

The aim of this study is to compare the type of infeed dispersions, i.e., fish oil (FO) emulsions stabilized by single-shelled pea protein isolate (PPI) and FO–PPI–sugar beet pectin (SBP) double-shelled complex coacervates on structural and physical properties of spray-dried FO microcapsules. The results show that FO–PPI–SBP complex coacervates formed at pH 3.5 possess bigger particle size and denser network structures rather than those produced at higher pHs (4.5 and 4.0). Nevertheless, the encapsulation performance of both types of infeed dispersions is quiet similar, and they afford a relative low encapsulation efficiency (22.80%–27.78%). FTIR confirms that electrostatic interaction dominates the formation of complex coacervates based microcapsules. SEM shows the spherical shape of all microparticles without cracking or fissures; while oil spot is visualized in emulsification based microcapsules. Unlike emulsification, DSC indicates the raised denaturation temperature of PPI in the FO microcapsules due to PPI–SBP interactions. This study suggests that PPI alone with a lower concentration is insufficient to microencapsulate fish oil; while the addition of SBP for the formation of double-shelled PPI–SBP complex coacervates particularly at pH 3.5 could be a practical and economic solution for fish oil microencapsulation. • Plant protein (PPI) and pectin (SBP) are used to produce fish oil (FO) powders. • FO infeed dispersions are prepared via PPI emulsions or PPI-SBP complex coacervates. • pH is critical to determine physical properties of dispersions and microcapsules. • Encapsulation performance is independent of the type of infeed dispersions. • Smooth surface without cracks or holes are revealed for microcapsules with PPI-SBP

Comparative evaluation of the yield strength of ferrite-pearlite steels by structure parameters

The influence of different hardening mechanisms on the yield strength of carbon and low-alloy steels is studied. It is established that for Ст.5пс hot-rolled steel, the greatest influence on the yield strength is exerted by solid-solution and grain-boundary hardening, and for 16Г2АФ low-alloyed steel, in addition to these types of hardening, it is also dispersion type. It is shown that thermomechanical treatment of Ст.5пс steel increases dislocation hardening as a result of a decrease in the increase in the density of dislocations and their preservation during accelerated cooling of hot-worked austenite in rolled products. Keywords: hardening, yield strength, thermomechanical treatment, accelerated cooling, phase components, grain size. aman-kanaev2012@yandex.ru, remshev@mail.ru, mash-kalugin@yande.ru, aliya-981@mail.ru

Coatings for sustainable paper-based flexible packaging: Barrier properties and processability

In this study, the use of waterborne barrier dispersions from trademarked BLUEWAVE Mechanical Dispersion Technology as thin coatings for paper-based flexible packaging was investigated. Prototypes were designed and examined for their performance in process, rheology, barrier, heat-seal/hot-tack, and coefficient of friction (CoF). Compositional details such as the type and amount of base resins and dispersants were found to significantly impact performances and were key to the development of new prototypes that deliver the performance profiles for implementation in paper-based flexible packaging applications.

A Double Perovskite BaSrZrMnO6: Synthesis, Microstructural, Transport and Ferroelectric Properties

In this paper, the synthesis and characterization (structural, dielectric, electrical and optical) of a double perovskite, BaSrZrMnO6 (BSZMO), by a conventional solid-state reaction route are reported. The sample has an orthorhombic crystal symmetry with an average crystallite size of 40.7[Formula: see text]nm and a micro-lattice strain of 0.226%. A microstructural and compositional analysis was presented by using a scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDX), respectively. Grains are well-grown and distributed uniformly through well-defined grain boundaries on the sample surface to enhance physical properties. EDX analysis confirms the presence of all constituent elements and is well-supported by the Raman study. The analysis of the UV–Visible spectrum reveals an energy bandgap of 2.1[Formula: see text]eV, suitable for photovoltaic applications. The study of dielectric properties as a function of temperature and frequency reveals a Maxwell–Wagner type of dispersion and explores possible applications in energy storage devices. The discussion on the impedance spectroscopy supports the negative temperature coefficient of resistance (NTCR) character whereas the modulus study suggests a non-Debye type of relaxation in the sample. The study of AC conductivity confirms a thermally activated relaxation process. Both Nyquist and Cole–Cole plots support the semiconducting nature of the sample. The study of resistance versus temperature ([Formula: see text]) supports NTC thermistor character for temperature sensor applications. The analysis of the P-E loop reveals the possibility of the ferroelectrics’ character.

Effects of elevated temperature steam oxidation and subsequent quenching on light water reactor clad

Following a postulated severe accident, the temperature of fuel pins of light water reactor escalates because of decay heat and devoid of coolant. The presence of steam inside the core causes exothermic oxidation of the cladding surface at elevated temperatures. The in-vessel injection system of severe accident management guidelines injects the cold water inside the hot uncovered core to arrest the escalation of temperature rise and terminate the accident progression. However, the heated clad may be subjected to thermal shock during the quenching process, which inevitably assists in the failure and fragmentation of the severely oxidised fuel pins column.In this paper, the effect of thermal quenching shock on the severely oxidised fuel pins column during the reflooding of the hot uncovered core is studied experimentally. A 2ˣ2 square lattice arrangement of zircaloy-4 clads is used for experiments. First, the clads are oxidised in the presence of steam in the temperature range of 1100–1250 °C, and then the test-section is flooded with water at ambient temperature from its bottom. The violent heat transfer between the clad and cold water has been observed during the reflooding. Furthermore, the clad has failed with a circumferential crack at multiple locations along the clad length during this period; however, longitudinal cracks are not observed on the clad surface. The scanning electron micrographs of the clad samples show a significant oxide layer over the clad surface. At the same time, energy dispersive x-ray spectroscopy reveals significant oxygen diffusion inside the zirconium metal matrix, particularly near the outer tube surface.Additional experiments are performed to study the clad failure mechanism during the reflooding of the severely oxidised clad. The set of experiments reveals that the clad fails under the thermal quench shock (>7.41 °C/s) for severely oxidised cladding (ECR>25%) at an average temperature above 1100 °C. The failed clad is likely to create debris. The average quench front velocity is 0.6 cm/s while the reflood velocity is 1.13 cm/s. Quench velocity below the reflood velocity indicates excessive water evaporation and dispersed type flow ahead of the quench front. The total analytical H2 generated before reflooding is 3.75 g.

Breaking down the components of the competition-colonization trade-off: New insights into its role in diverse systems.

Performance trade-offs between competition and colonization can be an important mechanism facilitating regional coexistence of competitors. However, empirical evidence for this trade-off is mixed, raising questions about the extent to which it shapes diverse ecological communities. Here, we outline a framework that can be used to improve empirical tests of the competition-colonization trade-off. We argue that tests of the competition-colonization trade-off have been diverted into unproductive paths when dispersal mode and/or competition type have been inadequately defined. To generate comparative predictions of associations between dispersal and competitive performance, we develop a conceptual trait-based framework that clarifies how dispersal mode and type of competitor shape this trade-off at the stage of dispersal and establishment in a variety of systems. Our framework suggests that competition-colonization trade-offs may be less common for passively dispersing organisms when competitive dominants are those best able to withstand resource depletion (competitive response), and for active dispersers when traits for dispersal performance are positively associated with resource pre-emption (competitive effect). The framework presented here is designed to provide common ground for researchers working in different systems in order to prompt more effective assessment of this performance trade-off and its role in shaping community structure. By delineating key system properties that mediate the trade-off between competitive and colonization performance and their relationship to individual-level traits, researchers in disparate systems can structure their predictions about this trade-off more effectively and compare across systems more clearly.

Binder stabilization and rheology optimization for vat-photopolymerization 3D printing of silica-based ceramic mixtures

Enhancing inlet gas temperature in aero/gas turbines to reduce their carbon-footprint, has led to a strive for better performing inlet cooling mechanism of the turbine blades. The internal cooling of the blades is made by ceramic cores in their casting process, but conventional ceramic molding has long reached its maximum possible geometrical complexity, hence shedding light on 3D printing of these cores. The objective of this study is to develop low-viscous, fully stabilized, commercially viable ink for vat-photopolymerization of silica-based ceramics. This paper investigates the best dispersion type and amount for different formulated monomer mixtures, and explains the best correlation between viscosity, solid loading, binders, dispersants, peeling forces and mechanical properties, and offers an optimized mixture to avoid the common ceramic printing issue, namely crack propagation of cores during sintering. Among five dispersant agents, the SOL20, SOL24 and FA4611 exhibited better performance than other dispersion agents, and the optimum concentration level for each binder and dispersant agent was ensured through sedimentation test. Their dispersion capability and long-term stability were further investigated to designate the best dispersion agent for each binder system. Further verification was made by sedimentation study of the samples at 40 °C for 40 days and reducing the superficial area of the used powder mixture. According to the result of the rheology analysis, the best dispersions were achieved using SOL20 for the loaded binder mixtures of M1 and M4, SOL24 for M3and FA4611 for M2. The instability of M1 and M2 with their respective dispersant agent was coordinated through the thixotropic agent of TX/2, and complete stabilization and near-Newtonian behavior were achieved. However, the research showed that the addition of TX/2 to fully stabilized M4 and M2 suspensions negatively impacts the mixtures’ rheological behavior from near-Newtonian to shear-thickening. In the final stage of this study, peeling forces, sintering and three-point bending tests were conducted to determine the final formulated suspension to print ceramic core components. M4 and SOL20 combination was selected for SiO2-ZrSiO4 loading and dispersing, respectively. The impact of solid loading between the range of 58 and 65 vol% on the rheological behavior of the final suspension and the mechanical properties of sintered bodies were investigated to assign an optimum solid rate. The adequate strength on sintered and degree of viscosity for ceramic vat-polymerization processing was achieved at 58 vol%. Lastly, a validation study is conducted by printing a complex ceramic core model by a commercial LCD hobby printer. This validation shows the significance of this study to scale up the manufacturing of complex-shaped ceramic cores and to revolutionize the sector, by printing inexpensive and readily available irregular-shaped (non-atomized) ceramic powder, using the most cost-effective LCD printers (non-specialized expensive ceramic printers).