Dispersed Composites Research Articles

Оценка качества коптильного дыма на основе его физико-химических характеристик

The work is devoted to the study of the physico-chemical characteristics of wood smoke used in the production of hot and cold smoked fish. The dispersion composition of wood smoke is determined depending on the temperature in the smoke formation zone and the excess air coefficient. The content of the main smoky components and polyaromatic hydrocarbons (PAHs) in the particles of the dispersed phase of wood smoke of various sizes has been established. A model of changing the dispersed compo-sition of smoky smoke in the process of hot smoking is proposed. Theoretical calculations based on the proposed models of changes in the dispersed composition have been experimentally confirmed.
 Physico-chemical and statistical research methods were used in the work.

Повышение экологической безопасности коптильного производства в соответствии с принципами устойчивого развития

The work is devoted to the study of the physico-chemical characteristics of wood smoke used in the production of hot and cold smoked fish. The dispersion composition of wood smoke is determined depending on the temperature in the smoke formation zone and the excess air coefficient. The content of the main smoky components and polyaromatic hydrocarbons (PAHs) in the particles of the dispersed phase of wood smoke of various sizes has been established. A model of changing the dispersed composition of smoky smoke in the process of hot smoking is proposed. Theoretical calculations based on the proposed models of changes in the dispersed composition have been experimentally confirmed.
 Physico-chemical and statistical research methods were used in the work.

Reactive extraction evaluation for vanadium (V) removal in the MRDC column using axial dispersion and central composition approach

Reactive extraction evaluation for vanadium (V) removal in the MRDC column using axial dispersion and central composition approach

Modelling and Comparative Analysis of Epoxy-Fly-Ash Composite with Alloys for Bracket Application

The current study compares and analyses the fly-ash–epoxy composite structure with alloys for bracket applications. A dispersed reinforcement composite is created by combining epoxy and fly-ash. Three different prototypical brackets are modelled and analysed using the finite element method, and their results are compared to common alloys used in the manufacture of L-shaped brackets. The mechanical properties of the composite material are calculated using a rule of mixtures, and the properties of the composite material are modified by changing the percentage composition of fly-ash. Based on equivalent stress and total deformation, all geometrical models are analysed and compared. The analysis results appear to be appropriate for broadening the scope of the application of epoxy-based composites for small-scale and large-scale applications. The results also show that the composite material can be used to make a variety of structural elements with high design complexity, such as bulkheads and other structural components.

Evaluation of shear property of Screw pine fiber/glass fiber reinforced vinyl ester hybrid composites

To evaluate the shear property, screw pine fibers are hybridized with glass fibers in a vinyl ester resin matrix. Two types of screw pine/glass fiber reinforced vinyl ester hybrid composites were created (dispersed and skin-core). A hydraulic compression molding method was used to create composites with a total fiber loading of 35.12 vol%. The shear property of composites was evaluated based on their form. After tests, scanning electron microscopy was used to conduct fractographic studies on the fracture surface of the hybrid composite specimen. Furthermore, neat resin samples and Screw pine alone composites were prepared and tested for comparison. The results revealed that the addition of glass fiber increased the shear property of composites. In both types of composites, the composite with 18.59 vol% Screw pine fibers and 16.53 vol% glass fibers has a high level of shear property. However, the skin-core type composites outperformed the dispersed type composites.

Повышение эффективности возврата уноса в котлах со слоевыми топками

A significant disadvantage of grate stokers is great carbon loss. To reduce these losses, the ash caught in the flue is returned to the furnace for afterburning. The effectiveness of this measure depends on the thermal characteristics of coal, the size of the pieces of coal and ash, the degree of carbon elimination, and the design features of the combustion chamber. Normative techniques to calculate and design grate stokers do not consider the features of coal combustion with ash return. Thus, it is relevant to develop the models that describe the creation of ash flows in the boiler path depending on its design, properties and dispersed composition of the burned coal and the aerodynamics of the combustion chamber. Mathematic simulation of the processes of particle size classification has been carried out to describe the creation of ash mass flows on the grate and in the convection chamber. To evaluate the parameters of mathematical models, simulation modeling of gas dynamics of flue gases in the combustion chamber has been carried out with SolidWorks software. The authors have developed a mathematical model and the method to identify its parameters. It allows us to obtain quantitative estimates of the economic efficiency of boilers with grate firing of coal. Thus, a computer program has been developed. The authors have used the program and the Neryungri brown coal to burn in the KV-TS-30-150 boiler. The results have shown that carbon loss without fly ash reinjection is 11,27 %. Introduction of fly-coke return unit reduces the loss up to 10,45 %. It is established that elimination of slit windows in the rotary baffle will lead to a change of the trajectories of ash particles and carbon losses reduction up to 10,17 %. Limiting the maximum size of coal pieces to 50 mm will lead to a more noticeable increase of boiler efficiency. The calculations have showed that in case the value of the carbon burn out factor equals 0,935, the carbon loss when the system of fly ash reinjection is turned off, its commissioning and, in addition, an increase of the gas density of the rotary screen will be 4 ,88%, 4,44% and 4,3% respectively. In case of a more careful assessment of the burnout factor at the level of 0,9, the carbon loss will be 7,51%, 6,87% and 6,65% respectively. The developed mathematical model makes it possible to evaluate the effect of the operation of the fly ash reinjection unit on the efficiency of the operation of a boiler with a grate stoker. Validation of a model for adequacy and for accuracy increase can be carried out after field testing of the boiler equipment.

Distribution functions of magnetic moments and relaxation times for magnetic fluids exhibiting controllable microstructure evolution

The paper presents experimental and numerical studies of laboratory magnetic fluid samples that differ significantly from each other by dispersion compositions (particle size distributions). We propose and justify a new technique for describing the magneto-granulometric properties of magnetic fluids. Our approach is based on the analysis of distribution functions of magnetic moments and their relaxation times. It can be used to determine the magnetic response of any magnetic fluid with arbitrary particle size distribution f(x) and arbitrary microstructure, including magnetic fluids undergoing phase transition. No intermediary representation of the f(x) function is needed. It is shown that a priori standard distribution functions f(x) cannot describe the ferrofluid microstructure features, specifically those related to the formation of nanoparticle aggregates. The distributions of magnetic moments and their relaxation times were obtained by means of a regularized numerical inversion of experimental static magnetization and dynamic susceptibility curves. These distributions contain full information about the microstructure of ferrofluids. Analysis of the distribution curves showed the temperature-dependent evolution of the ferrofluid microstructure in the zero applied magnetic field: particle aggregates form or disintegrate and magnetic moment relaxation mechanism changes depending on the temperature.

Advanced Electron Microscopy Techniques for PGM-Free Catalyst Characterization

Hydrogen fuel cells currently rely on expensive platinum group metal nanoparticle catalysts [1]. For green hydrogen production and utilization to become widely commercially viable, the cost of the devices that produce and utilize hydrogen must be significantly reduced. Platinum group metal-free (PGM-free) catalysts have the potential to greatly reduce this cost, and materials consisting of single transition metal atoms embedded in a nitrogen-doped graphitic carbon structure have shown particular promise for use as fuel cell cathodes [2]. A better understanding of the active site properties in these materials is still needed, however, to improve their stability and design new active site structures with enhanced properties [3]. Due to the atomic-scale nature of the active sites in these materials, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) have proven invaluable for demonstrating their atomically dispersed nature and composition [4]. Conventional STEM techniques have limited ability to correlate the local bonding environment and oxidation state of the metal atoms, for example, or track changes in the catalyst structure both during synthesis and as a result of cycling, which would provide a deeper understanding of the relationship between active site and catalyst properties.Here, we demonstrate advanced electron microscopy techniques that provide both enhanced and previously inaccessible information about PGM-free catalysts and their active sites. We show developments in automated identification of metal atom positions, which we use both to generate statistics about interatomic distances and to automatically position the STEM probe on individual atoms for EELS data acquisition. The former allows information about the presence of dual-metal site structures to be extracted, for example, and the latter allows compositional information with improved SNR to be obtained. Rapid automatic probe positioning also presents the opportunity for measuring the effect of local bonding environment on metal atom oxidation state, which cannot be obtained manually since these sites are typically unstable under the beam. In addition, we will show identical-location STEM (IL-STEM) techniques that allow the evolution of catalyst morphology and properties to be tracked at high resolution across synthesis steps and accelerated stress tests [5]. In particular, we use IL-STEM imaging and EELS to track deposition of graphitic material on the surface of a PGM-free catalyst that significantly improves the material’s durability, as well as track the change in the nanoscale graphitic carbon structure of the material as a function of electrochemical cycling. By providing access to enhanced compositional and bonding state information, as well as the ability to track properties as a material evolves, these techniques will advance our knowledge of PGM-free catalysts and enable better control over their properties in the future, accelerating wide-spread use of hydrogen fuel cells [6].

The Influence of Discharge Mode on Morphology of Al–Ni Nanoparticles Prepared by Underwater Electrical Wire Explosion

We report the results of experiments investigating the influence of discharge mode on morphology of Al–Ni bimetallic nanoparticles prepared by underwater electrical explosion (UEE) of intertwined Al/Ni wire. The experiments were conducted using a pulsed power generator with the stored energy of [Formula: see text][Formula: see text]J (underheat mode) and [Formula: see text][Formula: see text]J (overheat mode), delivering to the intertwined Al/Ni wire a [Formula: see text][Formula: see text]kA current rising during [Formula: see text]s. By analyzing electrical signals, we conclude that there exists a competitive process between Al wire and Ni wire, and the latter always lags behind the former in various stages, duo to the difference of electrical resistivity. Using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS), the morphology and element composition of nanopowders obtained at underheat mode and overheat mode were studied. The results reveal that core-shell structured Al–Ni nanoparticles can be easily obtained at underheat mode, due to the mismatched specific surface energy and matching lattice type between aluminum and nickel. Besides, the Al–Ni powder prepared by underwater electrical wire explosion (UEWE) has a smaller particle size (less than 100[Formula: see text]nm) and more consistent particle size distribution compared with traditional preparation methods. These results show that UEWE is very attractive for the preparation of Al–Ni nanopowders, which is helpful in improving the specific surface area of Raney–Ni catalyst.

Assessment of the influence of the composition of atmospheric microparticles on redox homeostasis of alveolar macrophages

Introduction. The components and dimensions of suspended particulate matter (SPM) depend on territory, the sources of generation. The aim is to assess the relationship between the quality and dispersed composition of atmospheric SPMs with oxidative and antioxidant processes in alveolar macrophages. Materials and methods. The impact of actual multi component pollution of the surface layer of atmospheric air on alveolar macrophages (AMs) of Wistar rats was modelled. Correlations between the characteristics of AMs and pollution were assessed using the Spearman correlation coefficient. Results. The predominant contribution of the quality characteristics of SPM has been founded. The effect of the dispersed composition increases with an increase of the finely dispersed particles fraction. Metal particles have caused oxidative damage to lipids, with the formation of stable lipid products. The antioxidant system (AOS) has been characterized by the activation of compensatory response. Mineral components have caused irreversible oxidative damage to lipid and protein compounds, activating the thioredoxin formation. Soot particles have showed the most pathogenic effect, leading to oxidative damage to lipids, proteins, and nucleic acids. The AOS stress was accompanied by an increase in the formation of oxidized glutathione and thioredoxin, which performs restoration of proteins and DNA. Limitations. Our study characterizes the response of the AMs of a particular territory. Conclusion. The established tendencies characterize the impact of composition of SPMs of the urban atmospheric on AMs. The study made it possible to identify the most sensitive criteria for the response of AMs upon contact with atmospheric SPMs (thioredoxin, protein carbonyl, 8-hydroxy-2’-deoxyguanosine).

Investigation of the effect of structure-regulating additives on the properties of minced fish systems

The search for new effective structure-forming agents of natural origin in order to improve the technology of fish molded products is an urgent scientific and industrial problem. In the course of the study, to obtain minced fish systems, frozen pollock and pink salmon have been used that meet the technical requirements of the current regulatory documentation. Mixtures of cryoconcentrates from seafood, rice and wheat flour, and the enzyme transglutaminase are used as structure-regulating additives. Cryoconcentrates have been made from cucumaria, squid, Pacific herring milt, octopus skin, seaweed, and scallop mantle. The introduction of dry powdered cryoconcentrates of seafood, containing a significant amount of protein substances, has contributed to the binding of water and an increase in the water-retaining capacity of minced pink salmon and pollock. Based on the results of studying the physical, chemical, rheological and organoleptic properties of dispersed minced fish systems, rational amounts of structure-regulating additives have been established: seafood cryoconcentrates - 4.0-5.0 %; transglutaminase - 0.5 %; rice flour - 2.0 %; wheat flour - 1.0-2.0 %. Molded fish products (cutlets, sausages) containing structure-regulating additives had high organoleptic properties after heat treatment. The results of the research should be used in the development of formulations of fish dispersed compositions in the technologies of molded, emulsion and structured products. The established high water-binding capacity of seafood cryoconcentrates justifies the need to study them as natural cryoprotectors in refrigeration technologies.

ДИАГНОСТИКА ДИСПЕРСНОСТИ ПЫЛЕВЫХ ПОТОКОВ ПО СИГНАЛАМ АКУСТИЧЕСКОЙ ЭМИССИИ ПРИ СТРОИТЕЛЬНЫХ РАБОТАХ

A brief overview of existing approaches to the determination of the dispersed composition of dust during construction works with the definition of the most promising method is presented. The existing methods are divided into methods with pre-deposition, and without. Methods with pre-deposition require a lot of time and are used mainly for laboratory studies. Methods without pre-deposition make it possible to conduct measurements in real time, which distinguishes them favorably from the methods described above during construction works. One of these methods is acoustic, which also provides the possibility of non–destructive testing and is based on the registration of acoustic emission signals that occur during natural or forced vibration excitation of the systems being diagnosed.
 When analyzing the physical parameters of the dust flow, it was determined that the key signals are AE, which can be presented in the form of diagnostic amplitude-frequency Fourier spectra containing information about the fractional composition and concentrations of the dust and gas flow. From this spectrum, subspectrums corresponding to the selected intervals of dispersion and dust concentration are further distinguished.
 The resulting algorithm is applied first for reference dust carvings in order to form a data bank, on the basis of which further determination of the dust composition is made.
 This method requires the availability of special software, which currently exists in the form of a prototype, and, accordingly, needs further refinement.

Mechanism of Response of Alveolar Macrophages in Wistar Rats to the Composition of Atmospheric Suspensions

Atmospheric air quality is a crucial factor in the health of human populations. Suspended particulate matter (SPM) is one of the most dangerous components polluting urban air. The aim of the present article is to study the effect of model suspensions (MS) of SPM that are characteristic of the composition of atmospheric air at locations with various anthropogenic loads on redox processes in alveolar macrophages (AM). Atmospheric air sampling was carried out in the breathing zone according to the method developed by one of the authors. AM were isolated from bronchoalveolar lavage fluid of experimental animals. The MS of SPM were prepared in accordance with the actual air pollution: MS No. 1 corresponded to an area with a low man-made load, and MS No. 2 corresponded to an area with a high man-made load. Load tests with model suspensions were carried out for 2 days. Parameters of oxidant processes and antioxidant system (AOS) were determined in cells and culture media. The proportion of the influence of the qualitative and dispersed composition of MS and the indicator of intra-system tension were calculated based on correlation dependencies. The atmospheric air with a high man-made load was dominated by particles up to 10 µm, whereas air with an insignificant man-made load contained SPM of more than 10 µm in size. Unidirectional changes were observed due to an exposure to both model suspensions, but the most pronounced oxidative modifications of lipids, proteins and genetic structures were caused by the exposure to MS No. 2. When exposed to MS No. 1, the AOS maintained the redox balance at the physiological level, localizing the resulting destruction inside the cells. MS No. 2 caused the redox balance to shift towards oxidants, potentiating the generalization of the destruction process. An increase in the content or a longer stress-inducing effect of PM2.5 causes a depletion in the reserve capacity of the AOS and the transition of destruction processes to the systemic level, which contributes to the development of the preconditions for environmentally dependent pathology.

Boron carbide dispersed epoxy composites for gamma radiation shielding applications

The present article deals with the preparation of B4C dispersed epoxy composites for irradiation shielding applications. The samples of five different compositions were made through molding and curing route and were subjected to thermal characterization and irradiation attenuation studies. The thermal stability of the samples increased due to the intrinsic conductivity of the filler particles whereas the shielding performance of samples increased with an increased addition of B4C at lower energies due to photoelectric absorption than that at higher energies, which makes the as-prepared sample suitable for low dose shielding applications.

Manufacturing Features and Characteristics of Uranium Dioxide Pellets for Subcritical Assembly Fuel Rods

The influence of technological processes and manufacturing of uranium dioxide fuel pellets for fuel elements for experimental fuel assembly (FA-X) which was designed as an alternative fuel for the nuclear research installation (NRI) "Neutron Source Controlled by Electron Accelerator" were investigated. Unlike standard production processes of UO2 pellets, the special feature fabrication process of this nuclear fuel type is production of uranium dioxide powder with enrichment of 4.4 %wt. of 235U achieved by mixing of two batches of powders with different uranium contents: 0.4 %wt. 235U and 19.7%wt. 235U, as well as ensuring the required tolerance of fuel pellets without the use of machining operations. A set of design and process documentation were developed in the R&D Center at NSC KIPT. Experimental stack of fuel pellets, fuel elements and a pilot fuel assembly FA-X were fabricated and designed to be compatible and interchangeable with VVR-M2 fuel assembly adopted as a standard assembly for the first fuel loading at the "Neutron Source Driven by an Electron Accelerator" FA. As opposition to the variant of VVR-M2 fuel assembly which consisted of three fuel rods of tubular shape with dispersion composition UO2‑Al, FA-X accommodates six fuel rods of pin-type with UO2 pellet which located in the zirconium cladding (E110) as the closest analogue of fuel rods of VVER-1000 power reactor. Inside cladding locate a 500 mm high fuel stack which is secured against displacement by a spacer. In the basic variant of FA-X the fuel pellets are made of UO2 with 235U enrichment near 4.4 %wt.

Effective properties of two-dimensional dispersed composites. Part II. Revision of self-consistent methods

The generalized alternating method of Schwarz was applied to boundary value problems for a multiply connected domain in the prior work Part I [62] . Approximate analytical formulas for the effective properties of dispersed composites with the exactly derived precision of their validity in concentration and in contrast parameter were derived. The present paper is devoted to comparison study of the formulas from Part I and the previously used engineering approximations. It is demonstrated that self-consistent methods (effective medium approximation, mean field, Mori-Tanaka methods etc) can be considered as the first order approximation of Schwarz's method. Implementation of the reiterated homogenization by means of Schwarz's method is also analyzed. This investigation explains a plenty of illusory different formulas which are actually reduced to the same lower order estimations for dilute composites. Some self-consistent methods violate the principles of homogenization and lead to methodologically misleading approaches. • A self-consistent method for composites is reduced to Schwarz's alternating method. • A methodology to study dispersed random composites is developed. • Limitations of various self-consistent methods are analyzed.

Characteristics of generated aerosol suspensions-complexes at traditional and modernized aluminum electrolysis technologies

Introduction. Assessment of occupational risk and mechanisms of workers' health disorders due to exposure to complex aerosol suspensions determines the need for in-depth study of the physicochemical properties of dust particles in the air. The study aim was the assessment of the dispersion and chemical composition of complex aerosol suspensions affecting workers in traditional and modernized aluminum production technologies. Materials and methods. The monitoring of air pollution of the working area with soluble and insoluble fluorides, aluminum trioxide aerosols was carried out using standard analysis methods, the dispersed and chemical composition of aerosol suspensions was studied using scanning electron microscopy and energy dispersive X-ray microanalysis. Results. The highest average shift concentration of fluorides, exceeding the occupational exposure limit by 4.7-12.5 times, are observed in the working area of professions serving electrolyzers and anodes, with a predominance of insoluble fluorides over soluble ones. Cases of exceeding the occupational exposure limit of aluminum trioxide by 1.9-2.6 times were noted. Dust suspended in the air of the working area consists of highly and ultradispersed aerosol mixtures of various chemical nature, including particles of the nanoscale range, impurities of heavy metals and toxic compounds. Highly dispersed dust particles, mainly alumina and fluorocarbon compounds, dominated in the air of workshops with traditional aluminum electrolysis technology, while micro- and nanoparticles, consisting mainly of cryolite and a mixture of aluminum fluoride with alumina, dominated in the modernized one. Conclusion. The exposure of complex multicomponent aerosol mixtures of aluminum production can pose a danger to the health of workers, which requires an in-depth analysis of the chemical and dispersed composition of aerosols when assessing the exposure of the dust factor and improving the complexes of preventive measures to prevent the development of diseases.

Thermal, mechanical and barrier properties of rice husk ash biosilica toughened epoxy biocomposite coating for structural application

The mechanical, thermal, and barrier characteristics of an epoxy biocomposite coating made using rice husk biomass biosilica were investigated in this study. The primary objective of this research was to find out whether and how adding biosilica from biomass rice husks improve the polymeric coating material's properties and adopted as sustainable coating element. The thermo-chemical approach and an aqueous solution method were adopted to transform the rice husk ash into the biosilica and in silane treated form. The ultrasonicator was used to mix the biosilica particles with resin to create the composite coating material. The prepared coating material was then characterized using ASTM standards in order to evaluate the effects of biosilica addition. According to the results, the tensile and flexural properties were improved by the inclusion of silica particles up to 1 and 2 vol%. However the properties are reduced when the biosilica amount was increased up to 4 vol%. In contrast, the hardness and thermal conductivity of the 4 vol% of biosilica dispersed composite was 94 shore-D and 0.42 W/mK, respectively. In terms of mass loss stability, the 4 vol% biosilica dispersed composite outperformed. After the biosilica particle was added, the barrier behavior showed good resistance to oxygen penetration. However, the stability of water permeation was moderately affected. As a coating material for corrosion-prone metallic surfaces and other household coating applications, these mechanically enhanced, thermally strengthened, and barrier property strengthened biosilica-epoxy composites could be applied.

Increasing the Efficiency of Taxifolin Encapsulation in Saccharomyces cerevisiae Yeast Cells Based on Ultrasonic Microstructuring

The aim of the present study was to investigate the possibility of encapsulating the plant antioxidant taxifolin in the living cells of the yeast Saccharomyces cerevisiae. Taxifolin is an unstable substance prone to oxidative degradation and actively enters into chemical reactions with a decrease or loss of bioactive properties. To minimize these problems, the use of encapsulation technology has been proposed. The cells of the yeast Saccharomyces cerevisiae have been chosen as a protective material for taxifolin. The encapsulation process was carried out using simple diffusion methods in living Saccharomyces cerevisiae cells in a thermostatically controlled shaker for 24 h. The aim of the study was to evaluate the effect of preliminary microstructuring of taxifolin on the efficiency of its encapsulation in yeast cells. The microstructuring process was carried out using low-frequency ultrasonic cavitation exposure for 7 min with a frequency of 22 ± 1.6 kHz and a power of 600 W/100 mL. The studies confirmed the feasibility of the proposed approach. It was found that microstructuring changes the dispersed composition of taxifolin particles and their morphology in solution and also increases the value of the antioxidant activity. Preliminary microstructuring of taxifolin increases the efficiency of its encapsulation in Saccharomyces cerevisiae yeast cells by 1.42 times compared to the initial form. A positive dependence of the growth of the encapsulation efficiency on the duration of the process was also established. Thus, the conducted studies confirmed the advantage of encapsulation of taxifolin in living cells of the yeast Saccharomyces cerevisiae in microstructured form.

Arbuscular Mycorrhizal Fungi Taxa Show Variable Patterns of Micro-Scale Dispersal in Prairie Restorations.

Human land use disturbance is a major contributor to the loss of natural plant communities, and this is particularly true in areas used for agriculture, such as the Midwestern tallgrass prairies of the United States. Previous work has shown that arbuscular mycorrhizal fungi (AMF) additions can increase native plant survival and success in plant community restorations, but the dispersal of AMF in these systems is poorly understood. In this study, we examined the dispersal of AMF taxa inoculated into four tallgrass prairie restorations. At each site, we inoculated native plant species with greenhouse-cultured native AMF taxa or whole soil collected from a nearby unplowed prairie. We monitored AMF dispersal, AMF biomass, plant growth, and plant community composition, at different distances from inoculation. In two sites, we assessed the role of plant hosts in dispersal, by placing known AMF hosts in a “bridge” and “island” pattern on either side of the inoculation points. We found that AMF taxa differ in their dispersal ability, with some taxa spreading to 2-m in the first year and others remaining closer to the inoculation point. We also found evidence that AMF spread altered non-inoculated neighboring plant growth and community composition in certain sites. These results represent the most comprehensive attempt to date to evaluate AMF spread.