Sedimentation Tendency Research Articles

Oxygen-limited pyrolysis and incineration impact on biochar transport.

At present, studies on biochar transport have focused on biochar obtained by oxygen-limited pyrolysis, which may differ from conventional biochar produced by incineration in nature. This work investigated the transport and retention mechanisms of three types of oxygen-limited pyrolytic biochar and three types of traditional biochar in saturated porous media. The results showed that the specific surface area of the three oxygen-limited pyrolysis biochar (180-200 m2·g-1) was higher than that of the traditional biochar (50-60 m2·g-1). Therefore, the retention capacity of pyrolytic biochar is strong and the permeability is less than 0.1. The absolute value of the zeta potential of traditional biochar is greater than 30mV, and the electrostatic repulsion generated is stronger, with a peak penetration rate of 0.16. Moreover, the zeta potential of biochar and traditional biochar is regulated by pH value and ionic strength. In acidic conditions or solutions with high ionic strength, the zeta potentials of the six types of biochar changed to about - 15mV, and the second minimum value was less than 0, indicating that there was a tendency for sedimentation. This study provides a new perspective for assessing the transport and environmental risks of biochar in the environment.

Antibacterial and degradation properties of dialdehyded and aminohexamethylated nanocelluloses

Dialdehyde cellulose nanofibrils (CNF) and nanocrystals (CNC) were prepared via periodate oxidation (CNF/CNC-ox) and subsequently functionalized with hexamethylenediamine (HMDA) via a Schiff-base reaction, resulting in partially crosslinked micro-sized (0.5–10 μm) particles (CNF/CNC-ox-HMDA) with an aggregation and sedimentation tendency in an aqueous media, as assessed by Dynamic Light Scattering and Scanning Electron Microscopy. The antibacterial efficacy, aquatic in vivo (to Daphnia magna) and human in vitro (to A594 lung cells) toxicities, and degradation profiles in composting soil of all forms of CNF/CNC were assessed to define their safety profile. CNF/CNC-ox-HMDA exhibited higher antibacterial activity than CNF/CNC-ox and higher against Gram-positive S. aureus than Gram-negative E. coli, yielding a bacteria reduction of >90 % after 24 h of exposure at the minimum (≤2 mg/mL), but potentially moderately/aquatic and low/human toxic concentrations (≥50 mg/L). The presence of anionic, un/protonated amino-hydrophobized groups in addition to unconjugated aldehydes of hydrodynamically smaller (<1 μm) CNC-ox-HMDA increased the reduction of both bacteria to log 9 at ≥4 mg/mL and their bactericidal activity. While only CNF/CNC-ox can be considered as biosafe and up to >80 % biodegradable within 24 weeks, this process was inhibited for the CNF/CNC-ox-HMDA. This indicated their different stability, application and disposal after use (composting vs. recycling).

Neural network ensemble model for prediction of erythrocyte sedimentation rate (ESR) using partial least squares regression

The erythrocyte sedimentation rate (ESR) is a non-specific blood test for determining inflammatory conditions. However, the long measurement time (60 min) to obtain ESR is an obstacle for a prompt evaluation. In this study, to reduce the measurement time of ESR, deep neural networks (DNNs) were applied to the sedimentation tendency of blood samples. DNNs using multilayer perceptron (MLP), long short-term memory (LSTM), and gated recurrent unit (GRU) were assessed and compared to determine a suitable length of time for the input sequence. To avoid overfitting, a stacking ensemble learning was adopted, which combines multiple models by using a meta model. Four meta models were compared: mean, median, least absolute shrinkage and selection operator, and partial least squares regression (PLSR) schemes. From the empirical results, LSTM and GRU models have better prediction than MLP over sequence lengths of 5 to 20 min. The decrease in overline{mathrm{MAPE} } and overline{mathrm{RMSE} } of GRU and LSTM was attenuated after a sequence length of 15 min, so the input sequence length is determined as 15 min. In terms of the meta model, the statistical comparison suggests that GRU combined with PLSR (GRU–PLSR) is the best case. Then, the GRU–PLSR was tested for prediction of ESR data obtained from periodontitis patients to check its applicability to a specific disease. The Bland–Altman plot shows acceptable agreement between measured and predicted ESR values. Based on the results, the GRU–PLSR can predict ESR with improved performance within 15 min and has potential applicability to ESR data with inflammatory and non-inflammatory conditions.

A Study on the Shoreline Movement of Won-pyeong Beach using ShorelineS Model

Increased coastal human intervention and climate change are leading to rapid changes in coastal areas and often causing catastrophic damage to resident populations. The ShorelineS model was introduced, which can explain drastic beach changes were simulated. According to the modeling results, the installation of Gungchon Port caused rapid sedimentation in the south of the port. It was reviewed that the erosion and sedimentation tendency of the beach is changed after the installation breakwater in front of the beach, the erosion in the central part of the beach was somewhat suppressed, and the beach was deposited in the shape of tombolo on the back of the beach. The installation of artificial structures dramatically changes the equilibrium state of the beach and increases the erosion of the direct wave near the structure. The ShorelineS model was the advantage of being able to properly reproduce changes in the coastline by inputting relatively simplified environment and beach information and to quickly predict after installation of artificial structures. The reallity, coastline changes due to various causes, so follow-up studies are needed to predict and effectively respond to this through an advanced model that reflects various conditions.

Silicone oil nanofluids dispersed with mesoporous crumpled graphene for medium-temperature direct absorption solar-thermal energy harvesting

Direct absorption and conversion of sunlight by optical nanofluids into storable heat is an efficient and facile way to harness abundant clean solar energy, but achieving long-term stable dispersion of the nanofluids is challenging under elevated temperatures. Herein, we report the preparation of mesoporous crumpled graphene particles as self-dispersible solar absorbers that can achieve homogenous dispersion within medium-temperature silicone oil. The mesoporous crumpled graphene particles were synthesized by using an aerosol-assisted capillary compression process and a subsequent oxidative-etching reaction. By controlling the etching time, the introduced mesopores can tune the apparent density of the crumpled particles into a value comparable with the dispersing base fluid. The crumpled surface structure, small particle size and compatible density weaken the inter-particle van der Waals attraction and gravitational sedimentation tendency. The resultant silicone oil nanofluids have maintained their uniform dispersion under a heating temperature of 200 °C for 50 h. The stable uniform dispersion together with the high solar absorptance, the large specific heat capacity and the proper viscosity enabled the application of prepared nanofluids for consistent high-performance medium-temperature solar-thermal energy harvesting under concentrated solar irradiation. • Mesopores are introduced to crumpled graphene particles to tailor the density. • Stable dispersion of mesoporous crumpled graphene particles in silicone oil is achieved. • The nanofluids have high solar absorptance, large heat capacity and suitable viscosity. • Medium-temperature nanofluidic solar-thermal energy harvesting is demonstrated.

Sediment Transport and Associated Long-term Bathymetric Changes due to Tidal Currents in The Seto Inland Sea, Japan

The topography of the seafloor is essential for determining physical phenomena such as ocean currents, favorable habitats for marine organisms, optimal vessel navigation, and so on. Prevailing currents and waves, as well as associated shear stresses acting on the ocean floor, are responsible for the formation of typical topographic features including sea caldrons and sandbanks through erosion of bedrock and sediments and their deposition processes. In the Seto Inland Sea (SIS), the most extensive semi-enclosed estuary in Japan, tidal currents affect pronouncedly the formation of seafloor topographic features; however, they have not been fully studied, particularly from a hydrodynamic viewpoint. This study aims to understand bathymetric formation under the predominance of tidal currents in the SIS. A 3-D high-resolution SIS circulation model based on the JCOPE2-ROMS system in a triple-nested configuration was utilized to examine the detailed hydrodynamic processes for the topography formations. A high correlation between the bottom shear stress and the scour depth of the erosive areas was observed, demonstrating that local tidal forcing has continuously been exerted on the seafloor to erode. A diagnostic sediment budget analysis was then conducted for sediments typical of the SIS, that is, gravel, sand, and clay, using the modeled circulation field. The horizontal divergence of the residual flows indicates consistency between divergence (convergence) and erosion (deposition). The sediment budget model also shows that these sediments are generally transported from deep to shallow areas in eroded terrains to form deposited terrains fringing the eroded terrains, whereas sedimentation tendency differs largely from location to location.

Stability, thermal conductivity and rheological properties of graphene and MWCNT in nanolubricant using additive surfactants

This study presents the stability, thermal conductivity and rheological properties of Graphene (GR) and Multi-wall carbon nanotube (MWCNT) in SUNISO SL68 Oil with different surfactants. Cetrimonium bromide (CTAB), Sodium Dodecylbenzene Sulfonate (SDBS), and Sorbitan monooleate (SPAN-80) are used as a surfactant. Zeta potential measurement was used to identify the agglomeration tendency of the samples. Visual observation, aided by an LED backlight, was used to investigate the sedimentation tendency of the samples. Thermal conductivity was measured to determine conductivity improvements of a nanolubricant with additive surfactants. Lastly, a cone and plate were used to measure the viscosity of the samples at different shear rates and temperatures. Zeta potential results were matched with visual observation results and CTAB is shown to be a better surfactant for both GR and MWCNT. Thermal conductivity analysis shows no significant improvement within the different surfactants, however, between 2% and 7% improvement is recorded when comparing nanolubricant to pure oil. A non-Newtonian fluid behaviour, specifically, Shear-thinning flow behaviour is observed in MWCNT nanolubricant samples, unlike the pure oil that shows a Newtonian fluid behaviour.

Manufacturing of Al2O3/Ni/Ti Composites Enhanced by Intermetallic Phases.

In this study, ceramic–metal composites in the Al2O3/Ti/Ni system were fabricated using the slip casting method. Two series of composites with 15 vol.% metal content and different solid phase contents were obtained and examined. A proper fabrication process allows obtaining composites enhanced by intermetallic phases. The microstructure of the base powders, slurries, and sintered composites was analyzed by scanning electron microscope. Analysis of the sedimentation tendency of slurries was carried out. The phase composition of the sintered samples was examined by X-ray diffraction analysis. A monotonic compression test was used to investigate the mechanical properties of the composites. A fractography investigation was also carried out. The research conducted revealed that the slip casting method allows the obtaining of composites enhanced by intermetallic phases (TiNi, Ni3Ti). The results show the correlation between solid-phase content, microstructure, and mechanical properties of the composites.

Patterning of Nano-Hydroxyapatite onto SiO2 and Electro-spun Mat Surfaces Using Dip-Pen Nanolithography

We have demonstrated the ability to controlled-pattern hydroxyapatite nanoparticles (nanoHA) onto the SiO2 and electrospun mat surfaces using dip-pen nanolithography (DPN). One of the keys to the success of this research was the formulation of nanoHA inks with well-defined physicochemical properties for specific use with dip-pen nanolithography. Studies on the effect of ink viscosity in terms of dispersion, stability, and accuracy of patterning determined the optimal formulation of ink as 3 w/v % nanoHA with 30-50% glycerol in isopropyl alcohol. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) were used to determine the dispersion of in solution. 30-50% glycerol solution yielded a dispersed nanoHA particles of size ~200 nm in ink. The stability of the inks evaluated by zeta-potential measurements and by turbidity (the tendency for nanoHA sedimentation over time) showed stability for the higher viscosity inks (30-50% glycerol formulated against 0% glycerol). Atomic force microscopy (AFM) and SEM were utilized to image the printed patterns on a SiO2 substrate and on an electrospun mat. The optimal ink consisted of 30% glycerol and 3 w/v % nanoHA with printed features ranging from 745 – 1175 nm on a SiO2 substrate. Additionally, nanoHA printed onto an electrospun scaffold showed DPN without fiber damage onto soft-matter. The development of a nanoHA ink for controlled DPN patterning will enable single cellular interactions to nanoscale patterning on many surfaces, including printed nanoHA-gradient-scaffold for interface tissue engineering.

Analysis of the Topography Change using the RAMMS Model and Numerical Modeling in the Korean East Sea Estuary

Choi, J.H.; Kin, S.D.; Jun, K.W.; Lee, H.J., and Tak, W.J., 2020. Analysis of the topography change using the RAMMS Model and numerical modeling in the Korean East Sea Estuary. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 422–427. Coconut Creek (Florida), ISSN 0749-0208.Recently, erosion and sedimentation imbalances have occurred on many coastlines due to the complex effects of man-made environment changes and natural environment changes caused by climate change. Problems including coastal erosion, shoreline topography changes, and estuary blockages require comprehensive management of sediments including coastal sediments and those discharged from rivers and mountains in the hinterland. This study quantitatively investigated the streamflow of sediments generated from mountains and examined the effect of discharged sediments on coastlines and beaches. First, the sediments in rivers and beaches from mountain areas were investigated on-site using terrestrial LiDAR. High-precision topography data were constructed by generating Digital Elevation Model (DEM). To calculate the amount of sediment discharged from mountain areas quantitatively by using constructed topography data, simulations were performed with the RAMMS model, a type of sediment-water flow analysis model. By applying an erosion and sedimentation model, the effects on the beach topography along the coast were analyzed. It was confirmed through the RAMMS model that the sediment flowed into the river when a mountainous disaster, such as landslide or debris-flow, occurred. The sediment that flowed into the river induced coastline and beach topography changes. In terms of the beach topography on the East Coast of South Korea, the north side of the estuary beach showed a significant sedimentation tendency and the south side of the beach showed a gradual erosion tendency. Furthermore, significant changes in the coastline were observed as a river-mouth blockage occurred at the estuary due to sediments deposited from the mountains and rivers in the coastal area. It is expected that the results of this study will provide useful information when establishing plans for the preservation of coastal areas in the future.

Effect of shape and size of filler particle on the aggregation and sedimentation behavior of the polymer composite

The agglomeration and sedimentation tendency of iron fillers with different particle size, shape, and the specific area was investigated by means of microstructural observation. The distribution of filler particles within polymer composite was investigated by the agglomeration and sedimentation tendency. The effect of regular and irregular fillers particles was considered in the silicon based polymer composite for uniform distribution within the volume of the matrix. The role of shape and size of the fillers were emphasized for the distribution and sedimentation behavior within the polymer composite. The extent of aggregation and sedimentation is always determined by the relative magnitude of attractive and separating forces under the sample preparation and testing condition. The effect of density and surface area has a significant effect on the dispersion within the composite. We could conclude that composites with sedimentation and aggregates possess lower mechanical properties.

Investigation of the Effect of Diamond Powder on the Thermal Properties of Octadecane Using Differential Scanning Calorimetry

Abstract The purpose of this work was to examine the effect of diamond powder on the thermal properties of phase change materials on the example of octadecane. The experiment involved mixing of diamond powder with a specific granulation with the aforementioned representative of the alkanes group. Two different grain sizes were used: 50 and 250 micrometres. The change of specific heat, latent heat of phase change and degree of supercoiling in newly formed mixtures was compared to the pure forms of the phase-change materials used. Initial mixing with a glass-stirring rod showed strong stratification for each granulation due to the low viscosity of the mixture and too large differences between component densities. It was decided to add amorphous silicon dioxide to the mixtures, which increases density of the mixture. The optimal percentage of amorphous silicon dioxide was estimated experimentally. Measurements of thermal parameters were carried out using DSC technology. The results of the tests of specific heat and latent phase transition heat showed that with the increasing content of diamond, the specific heat of the mixture decreases almost twice, and the latent heat can decrease by up to three times. The effect of diamond powder on reducing the degree of supercoiling of the mixture was also observed. An important observation was that the mixture with higher granulation of diamond powder had greater tendency for sedimentation. This method could be used to increase thermal conductivity and diffusivity of phase change materials and make them viable for use in systems that require cooling at high rate or temperature stabilization, such as control systems in electronic vehicles or aviation industry and at the same time decrease the degree of supercoiling which could increase the efficiency of system.

Self-assembly of kraft lignin-acrylamide polymers

Lignin has been produced in large quantities in the pulp manufacturing process; however, its valorization has been challenging. The production of lignin polymers has shown pathways to produce water soluble products to be used as flocculants and dispersants. However, these lignin-based polymers may interact with each other and form large flocs that could reduce their efficiency in interacting with other colloidal particles. This study aims at evaluating the self-assembly of kraft lignin-acrylamide polymers in aqueous environments under different salt concentrations. The sedimentation studies using a vertical scan analyzer showed that a higher molecular weight lignin polymer had a higher tendency for sedimentation than a lower molecular weight one. Quartz crystal microbalance with dissipation (QCM-D) was used for studying the self-assembly behavior of lignin polymers with different molecular weights. The results suggested that lignin polymer with the higher molecular weight of 96,992 g/mol had a higher tendency to self-assemble by forming a loose floc as compared to that with a lower molecular weight. Also, salt disrupted the self-assembly of lignin polymers greatly.

Experimental and numerical investigation of flow patterns in shallow rectangular reservoirs with symmetrically positioned inlet and outlet channels

ABSTRACT Shallow flows correspond to turbulent flows whose horizontal dimensions are considerably larger than the vertical one. In Hydraulic Engineering, they refer, e.g., to stormwater basins, stabilization ponds for wastewater treatment and aquaculture tanks. Since they involve low flow velocities, a continuous settling process often affects such shallow reservoirs. Therefore, it is important to expand the knowledge about the influence of its geometry on the hydrodynamic behavior and the sedimentation tendency. This paper aims to analyze flow patterns in a rectangular reservoir with symmetrically positioned upstream and downstream channels, taking into account three different flow rates under steady flow regime (0.50, 1.25 and 3.40 L/s). Experimental tests were performed in a laboratory prototype, consisted of a 3.0 m long and 2.0 m wide reservoir, with a maximum depth of 0.30 m. Also, it was applied the WOLF 2D software for numerical modeling of all variants. Experimentally, a symmetrical hydrodynamic behavior was observed only for the lowest flow rate, while the flow pattern was asymmetrical for the other cases. On the other hand, the numerical model indicated hydrodynamic symmetry for all scenarios.

Electrorheological Fluids with High Shear Stress Based on Wrinkly Tin Titanyl Oxalate.

Electrorheological (ER) fluids are considered as a type of smart fluids because their rheological characteristics can be altered through an electric field. The discovery of giant ER effect revived the researchers' interest in the ER technological area. However, the poor stability including the insufficient dynamic shear stress, the large leakage current density, and the sedimentation tendency still hinders their practical applications. Herein, we report a facile and scalable coprecipitation method for synthesizing surfactant-free tin titanyl oxalate (TTO) particles with tremella-like wrinkly microstructure (W-TTO). The W-TTO-based ER fluids exhibit enhanced ER activity compared to that of the pristine TTO because of the improved wettability between W-TTO and the silicone oil. In addition, the static yield stress and leakage current of W-TTO ER fluids also show a fine time stability during the 30 day tests. More importantly, the dynamic shear stress of W-TTO ER fluids can remain stable throughout the shear rate range, which is valuable for their use in engineering applications. The results in this work provided a promising strategy to solving the long-standing problem of ER fluid stability. Moreover, this convenient route of synthesis may be considered a green approach for the mass production of giant ER materials.

Numerical analysis of eccentric orifice plate using ANSYS Fluent software

In this paper the eccentric orifice plate is qualitative analysed as compared with the classical concentric orifice plate from the point of view of sedimentation tendency of solid particles in the fluid whose flow rate is measured. For this purpose, the numerical streamlines pattern will be compared for both orifice plates. The numerical analysis has been performed using ANSYS Fluent software. The methodology of CFD analysis is presented: creating the 3D solid model, fluid domain extraction, meshing, boundary condition, turbulence model, solving algorithm, convergence criterion, results and validation. Analysing the numerical streamlines, for the concentric orifice plate can be clearly observed two circumferential regions of separated flows, upstream and downstream of the orifice plate. The bottom part of these regions are the place where the solid particles could sediment. On the other hand, for the eccentric orifice plate, the streamlines pattern suggest that no sedimentation will occur because at the bottom area of the pipe there are no separated flows.

Early age evolution of rheological properties of over-stabilized bitumen emulsion-cement pastes

This paper focuses on the early age evolution of consistency and rheological properties of fresh bitumen emulsion-cement (BEC) pastes. The tested BEC pastes were fabricated using a Portland limestone cement and an over-stabilized bitumen emulsion and were characterized by water to cement ratio ranging between 0.33 and 1 and by bitumen to cement ratio ranging between 0 and 1. The testing plan included the measurement of sedimentation tendency, setting time and evolution of viscosity with increasing storage time. Rheological measurements were also carried out on bitumen emulsion-filler mastics prepared with a reference filler. Results showed that, regardless of water content, the initial and final setting time of BEC pastes increased when the proportion of bitumen with respect to cement was increased. When the total concentration of the dispersed phases was low, the increase in bitumen concentration with respect to cement led to a reduction in the rate of viscosity increase with storage time; on the other hand, when the total concentration of the dispersed phases was high the increase of storage time led to a change in the physical state of the pastes (from fluid to plastic) due to coalescence of bitumen droplets.

Structural analysis of chitosan hydrogels containing polymeric nanocapsules

The incorporation of different concentrations of polymeric nanocapsule suspensions into chitosan hydrogels is proposed, in order to study the structure of a formulation with the properties of great tissue adhesion and controlled release of the nanoencapsulated drugs, represented here by capsaicinoids. The gels presented acceptable acid pH values and the nanoparticles were visually observed in the system. A transition from the micrometer to the nanometer scales suggested that the nanocapsules are initially agglomerated in the hydrogel. A sedimentation tendency of the nanocapsules in the system was observed and only physical interaction between the chitosan chains and polymeric nanocapsules was verified. The hydrogels, despite the presence of nanocapsules, presented shear-thinning properties and an elastic behavior under low and high frequencies, showing a very structured gel network. The observed variation in the elasticity of the hydrogels may arise from a decrease in the number of interactions and degree of entanglement between the chitosan chains, caused by the presence of nanoparticles.

Physicochemical and geochemical characterization of geothermal waters sedimentation tendency at Sijarinska spa and Vranjska spa (Serbia)

A comprehensive analysis of physicochemical parameters in geothermal waters from the sites in Sijarinska spa (drill hole B-4) and Vranjska spa (drill hole VG-2) in order to investigate their tendency to form deposits in the pipe installation is presented. Drill holes B-4/VG-2 posses utilization capacity of 30/27 L s-1 with water temperatures 75/90 oC. VG-2 water does not show any tendency to (or shows very small) sedimentation compared to the B4 water. The behaviour of the geothermal water from the B-4 hole was examined in real condition in Sijarinska spa, by letting it flow through the pipe installation. The results of geochemical analysis of water B-4 show that aragonite is the predominant mineral in the sediment (98 %) with lesser amount of calcite, vaterite and anhydrite.

The phylogenetic position and phenotypic changes of a Chlorella-like alga during 5-year microcosm culture

Recent phylogenetic studies of Chlorella-like algae revealed that this group has diversified into free-living and endosymbiotic niches, the latter within protists and invertebrate organisms. Our previous studies using a long-term culture composed of an alga (Chlorella vulgaris, rDNA sequence unknown), a bacterium (Escherichia coli) and a ciliate (Tetrahymena thermophila), suggested that some clones in the algal population developed an endosymbiotic ability with T. thermophila while others developed an ectosymbiotic ability with E. coli from a non-associated stage. In this paper, an rDNA (18S, ITS1, 5.8S, ITS2)-based phylogeny of the ancestral strain and derived clones isolated from 5-year microcosm cultures was constructed and revealed that the alga belongs to the genus Micractinium. This result was supported by analysis of the secondary structure of the rRNA gene. No difference was observed in the sequence between the ancestral and derived clones. On the other hand, some morphological and physiological traits of the ancestral strain and the derived clones were analysed and revealed that several phenotypic changes had occurred among the algal clones. In particular, the derived clones obtained from long-term cultures had increased in cell size, changed in their ability to grow at pH 4.0, and developed a tendency for cell-aggregation or sedimentation.