Small-sized Particles Research Articles

Experimental study on the effects of sediment size gradation and suspended sediment concentration on the settling velocity, ws

The settling velocity of non-uniform sediment is of great importance for the sediment transport on coasts and estuaries. Although existing settling velocity formulas have already considered factors such as the Suspended Sediment Concentration (SSC), temperature, salinity, turbulence, and the effect of size gradation on the settling velocity, more studies are needed. In this study, the fiber optic sensors and Particle Track Velocimetry (PTV) for high SSC were used to measure the settling velocity of two size gradations with different SSCs in a settling column in laboratory. The size gradation curves and settling velocities of these two non-cohesive sediment with SSCs ranged from 0.1 kg/m3 to 50 kg/m3 were obtained. When the SSC is less than or equal to 0.1 kg/m3, the settling velocity is close to the grain size distribution weighted average settling velocity. With the increase of SSC, the distance between sediment particles decreases, and the mutual influence between different components become important, resulting in a decrease in the settling velocity of large-sized particles and an increase in the settling velocity of small-sized particles. This phenomenon is more pronounced for natural sediments. Based on the experimental results, a particle size distribution correction coefficient was proposed to fit the fine-grained settling velocity in quiescent water considering size gradation and sediment concentration.

Enhanced ignition and combustion performance of boron-based energetic materials through surface modification and titanium dioxides coating

The present study focuses on the removal of ineffective hydroxyl surface (B–OH) of the shell of pristine boron (B) particles, followed by its modification using a low-cost, eco-friendly, and non-hazardous ethylene glycol (EG). Subsequently, very small-sized titanium dioxide (TiO2) particles are coated onto the boron surface by adding titanium tetraisopropoxide (TTIP) precursors at room temperature. Characterization techniques were employed to investigate the structure and morphology of these materials. FTIR, XPS, and TEM analysis reveal that EG effectively removes ineffective boron hydroxyl surfaces and modifies the surface through passivation by its surface functionalities. Furthermore, EG assists in the coating very small-sized TiO2 particles on the boron surface. Thermal stability tests show that the modified boron surface and TiO2-coated boron surface exhibit earlier oxidation of the core boron compared to pristine boron. This enhanced capability for earlier oxidation of core boron was further investigated in the shock tube and bomb calorimeter for measurement of ignition delay time and heat of combustion. The findings demonstrate that room temperature synthesized TiO2-coated B particles (ignition delay time of ∼181 μs and heat of combustion of ∼17.3 kJ/g) outperform pristine B particles (ignition delay time of ∼284 μs and heat of combustion of ∼13.2 kJ/g). This improvement is attributed to the removal of ineffective boron hydroxyl surfaces, surface modification, uniform coating with very small TiO2 particles, the catalytic effect of TiO2 on oxygen diffusion, and effective oxidation of core boron. This study suggests that efficient energetic material can be achieved at room temperature with no potential harm to the environment.

Efficient Catalytic Oxidation of Ethylene at 0 °C on an in Situ Carbon Modified Pt Catalyst Supported on SBA-15.

The design of efficient catalysts for catalytic ethylene (C2H4) oxidation is of crucial importance for extending the shelf life of fruits and vegetables. Herein, a carbon modified SBA-15 supported Pt catalyst (Pt/CSBA-15) was prepared in situ by a facile solid phase grinding-infiltration-inert atmosphere calcination method. Characterization results reveal that in the Pt/CSBA-15 catalysts thin carbon layers are successfully formed in the hexagonal pores of SBA-15. Additionally, Pt particles are well dispersed in the channels of SBA-15, and Pt/CSBA-15 has a smaller Pt particle size than the catalyst without carbon modification (i.e., Pt/SBA-15). O2 is more feasibly adsorbed and activated on small-sized Pt particles, and in situ formed carbon species enhance the hydrophobicity of catalysts. As a result, both 3Pt/CSBA-15 and 5Pt/CSBA-15 are able to maintain 100% conversion of 50 ppm of C2H4 for more than 7 h at 0 °C. 3Pt/CSBA-15 even achieves 81.5% C2H4 conversion and 71.6% CO2 yield after 20 h, exhibiting much more prominent catalytic performances than 3Pt/SBA-15. DFT calculations and in situ FTIR measurements confirm that small-sized Pt particles possess strong O2 affinity to promote O2 adsorption, and in situ formed hydrophobic carbon layers efficiently suppress competitive H2O adsorption. Such a unique one-step catalyst preparation method for regulating the size of metal particles and the hydrophobicity of catalysts can be perfectly utilized to develop simple and efficient hydrophobic catalysts applied in low-temperature oxidation of C2H4.

Investigation of the separation of conductive and insulating objects on a laboratory made electrostatic separator

Electrostatic separators are widely used to separate conductive and insulating objects up to some millimetres in size. Modelling of such equipment has been presented in several studies; laboratory and numerical models have been analysed. However, there are such situations, where larger samples of the order of centimetres have to be separated, as milling them into smaller size particles is not allowed or feasible. It was found that electrostatic separation can be used even in such cases but in a different arrangement than in the “traditional” constructions.This paper is a continuation of a previous study, in which the separation of a constructed laboratory separator was examined. The model was built in a circular plate arrangement with high voltage needle electrodes above the edge of cylinder’s mantle, where the discharges are generated. The slope of the circular plate is steadily decreasing, so the samples on the edge of the plate produce an increasing angle of inclination along the circumference. Charged samples stick to the plate, uncharged ones fall off. Some key parameters as rotation speed, electrode distance, voltage level and position of ionizer electrodes were varied.

SOIL PHYSICAL QUALITY INDICES OF MINING-INDUCED DISTURBANCES IN SOIL WITHIN THE LOESS REGION OF WESTERN CHINA

Soil sampling and in situ measurements were conducted at 24 locations at three time points from May 2015 to April 2016. The statistical analysis showed that the variabilities of soil water content and soil penetration were moderate, while particle size and soil saturated hydraulic conductivity varied considerably. Rainfall before measurements contributed positively to the mean soil water content and negatively to particle size. This was mainly due to the soil aggregates and large soil particles being broken into smaller particles from rain splash. The detached small-sized soil particles could coalesce into larger-sized ones and even soil aggregates. Stressors in zones differ, resulting in variations between soil physical quality indices. The point-to-point comparisons indicated that the mean measured soil water content and soil saturated hydraulic conductivity were similar, if the measurements for these two indices were conducted under similar weather conditions during the same period between years. The investigation on the relationships among soil physical quality indices showed a negative relationship between the measured soil water content and soil saturated hydraulic conductivity. A positive correlation was also found between soil particle size and soil saturated hydraulic conductivity. Lower soil strength resulted in higher soil saturated hydraulic conductivity.

Smectite-bitumen interactions in non-aqueous bitumen extraction process

The non-aqueous extraction (NAE) is an alternative to the commercial water-based extraction technology used to liberate bitumen from oil sands. Although the impact of kaolinite, illite, chlorite, illite-smectite and montmorillonite on NAE process has been previously studied, the effect of different types of smectites has not been fully understood yet. In this work, mixtures of bitumen with bentonites dominated by saponite, hectorite, nontronite, beidellite and montmorillonite were reacted for several days and then washed with solvent (cyclohexane) to remove bitumen from the bentonites. The main goal was to better understand the impact of different smectites properties (specific surface area, pore structure characteristics, particle size, crystallite thickness, swelling ability, cation exchange capacity, layer charge and crystal-chemistry of smectites) on NAE process. The results showed that the porosity, particle size and swelling ability were the key parameters affecting the solvent-based bitumen recovery under the studied conditions. Samples with larger initial total pore volume and smaller particle size displayed reduced solvent bitumen extractability. The particle size of studied samples was affected primarily by swelling of smectites during the solvent bitumen extraction experiments. Smectites were swelling in water but not in cyclohexane. Swelling of smectite caused splitting of larger clay particles into many smaller particles. As a consequence, the efficiency of solvent bitumen extraction was significantly lower for fine grained samples, consisting of thin delaminated smectite particles, in which the bitumen was distributed among small-sized clay particles.

Investigation on sediment erosion in bucket region of Pelton turbine considering cavitation

In the context of constructing high-head hydro-power stations, the Pelton turbine assumes a critical role as the primary energy converter. This study employs the Eulerian–Lagrangian method to simulate the multi-phase flow occurring within the Pelton turbine bucket. Furthermore, it introduces a novel aspect by investigating and comparing the effects of cavitation on erosion within the bucket region under varying conditions of sediment-water, involving different particle sizes and concentrations. The research findings unveiled several key insights. Primarily, cavitation predominantly influences the flow characteristics of particles at the air–liquid interface, while particles with larger sizes tend to concentrate in the center of the jet. Consequently, cavitation's impact on erosion is more pronounced in the case of smaller-sized particles. Moreover, the study revealed that cavitation can either exacerbate erosion under high particle concentration conditions or mitigate it when particle concentration is low. Furthermore, the investigation highlighted variations in the degree of erosion and the affected area of the bucket based on different position angles. Particularly, at a position angle of 65°, the presence of water vapor induced by cavitation alters particle trajectories, thereby modifying the overall erosion pattern of the bucket. These findings collectively contribute to a deeper understanding of the complex interplay between cavitation and erosion within the Pelton turbine bucket.

Microstructures and mechanical properties of a γ-TiAl alloy modified by Gd additions

The microstructural evolutions and room-temperature tensile properties of Ti-45Al-2.5Nb-1.5Mo-(0-0.2)Gd were investigated in details. Experimental result revealed that there were precipitated particles, involving Gd2TiO5 and GdAl3, distributing within the microstructure of the Gd-containing TiAl alloys, and the increase in the Gd addition resulted in the aggregation of Gd-containing particles, forming a network structure along grain boundary and colony boundary. The addition of Gd also had a significant refining effect on the average inter-lamellar spacing. The ultimate/yield strength and elongation increased first and then decreased with the content of Gd. Gd addition did not change the mixed fracture mode of crack propagation along and across the lamellae. In the plastic deformation process of Gd-containing sample, except for dislocation gliding, twinning-controlled deformation mode occurred, contributing to the improvement of mechanical properties. Moreover, dislocations could directly cut through the small-size Gd-containing particle, while some dislocations would continue to slip via bypassing the large-size Gd-containing particle.

Tailoring compatibility and mechanical properties of cold-mixed epoxy asphalt via external epoxy group content manipulation

The compatibility of cold-mixed epoxy asphalt (CEA) significantly influences its mechanical properties, primarily mediated by the epoxy group content within CEA. However, the feasibility and mechanisms for regulating the external epoxy group content to achieve optimal performance have yet to be explored thoroughly. Herein, soybean oil, epoxidized soybean oil, and epoxy-terminated hyperbranched epoxy resin (EHER) were used to construct CEA with different external epoxy group contents, and their effects and mechanisms on the compatibility and mechanical properties of CEA were investigated based on experiments and molecular dynamics simulation. Our findings suggest that maintaining an external epoxy group content between 8.4%∼11.4% in the CEA blend and below 12.17% in the cured CEA is crucial. These criteria can be met by adding no more than 5 wt% EHER. CEA with 3 wt% EHER exhibited the most balanced compatibility and mechanical properties, characterized by a pot life of 91 min, a tensile strength of 5.02 MPa, an elongation at break of 61.3%, and a tensile toughness of 1.58 MJ/m3. The presence of external epoxy groups increased the cohesive energy density and the solubility parameter difference between epoxy resin and asphalt prior to curing, forming a "sea-island" structure with varying particle sizes, primarily comprising small-sized particles. This structure was preserved post-curing, establishing a stable system with minor energy alterations. Simultaneously, EHER enhanced the molecular rigidity and uniformity of CEA, thereby improving its mechanical properties. It is recommended to relate epoxy group content in CEA blends with indicators of compatibility and mechanical properties, enabling better prediction.

Analysis of the Sand Erosion Effect and Wear Mechanism of Wind Turbine Blade Coating

The wind–sand climate prevalent in the central and western regions of Inner Mongolia results in significant damage to wind turbine blade coatings due to sand erosion. This not only leads to a decline in power generation but also poses safety risks. This study replicated the wind–sand environment of Alashan and numerically simulated the erosion and wear process of the blade coatings of a 1.5 MW horizontal axis wind turbine under rotational conditions using the DPM model. Additionally, erosion tests were conducted on the operating wind rotor in a wind tunnel. The simulation results demonstrate that sand particle trajectories in the rotating domain are influenced by vortex, incoming wind speed, and sand particle size. For small-sized sand particles, variations in wind speed do not substantially alter the number of particles in contact with the wind turbine blades. However, alterations in the momentum of these particles lead to changes in the impact force on the coating surface. Conversely, the change of wind speed will not only alter the number of large-size sand particles in contact with the wind rotor but also modify the impact force on the coating surface. Furthermore, after impacting the blade, small sand particles continue to move along an approximate helical trajectory with the airflow, while large-size sand particles swiftly rebound. Through statistical analysis of erosion pits on the blade surface after the erosion experiments, it was observed that, in comparison among the leading edge, windward side, trailing edge, and leeward side, the leading edge presents the greatest number of erosion pits, whereas the leeward side has the fewest. Along the spanwise direction, the 0.7R-blade tip segment exhibits the highest count, while the blade root-0.3R section displays the fewest number of pits. The wear morphology of the blade coating was observed from the blade root to tip. The leading edge coating exhibits a range from shallow pits to coating flaking and deeper gouge pits. On the windward side, the coating displays wear patterns varying from tiny cutting pits to cutting marks, and then to gouge pits and coating flaking. Erosion morphology of the trailing edge evolves from only minor scratches to spalling pits, further deepening and enlarging. These research findings provide a basis for the study of zoning-adapted coating materials for wind turbine blades in wind–sand environments.

Microplastic pollution in waters of the Antarctic coastal environment of Potter Cove (25 de Mayo Island/King George Island, South Shetlands)

Plastic pollution in the Southern Ocean around Antarctica is a growing concern, but many areas in this vast region remain unexplored. This study provides the first comprehensive analysis of marine microplastic (MPs) concentrations in Potter Cove, located near the Argentinian Carlini research station on 25 de Mayo/King George Island, Antarctica. Water samples were collected at 14 sites within the cove, representing various influences from the station's activities. Two sampling methods were used: a 5 L Niskin bottle and an in-situ filtering device called Microfilter, allowing for large water volumes to be filtered. MPs were found in 100 % of the samples. Microfilter samples ranged from 0.02 to 2.14 MPs/L, with a mean concentration of 0.44 ± 0.44 MPs/L. Niskin bottle samples showed concentrations from 0.40 to 55.67 MPs/L, with a mean concentration of 19.03 ± 18.21 MPs/L. The dominant types of MPs were anthropogenic black, transparent, and pink microfibers (MFs) measuring between 0.11 and 3.6 mm (Microfilter) and 0.06 to 7.96 mm (Niskin bottle), with a median length of 0.01 mm for both methods. Transparent and black irregular microfragments (MFRs) with diameters from 0.10 to 5.08 mm and a median diameter of 0.49 mm were also prevalent. FTIR-spectroscopy revealed the presence of 14 types of polymers. Cellulose-based materials and polyethylene terephthalate were the most abundant in MFs, while polyurethanes and styrene-based copolymers dominated in MFRs. MPs were more abundant near the Carlini station. Compared to other coastal Antarctic areas, the MPs in the cove were relatively abundant and mostly smaller than 1 mm. Local activities on the island were identified as the primary source of MPs in the cove, and the cyclonic water circulation likely affects the distribution of small-sized particles. To protect the ecosystem, reducing plastic usage, improving waste management, regulating MPs debris, and enhancing wastewater practices are essential.

CFD Analysis of Microplastic Transport over the Slopes

Microplastics, ubiquitous in our environment, are significantly impacted by the hydrodynamic conditions around them. This study utilizes CFD to explore how various breaker types influence the dispersion and accumulation of microplastics in nearshore areas. A special focus is given to the impact of wave dynamics and particle size, particularly on buoyant microplastics in spilling breakers. It was discovered that spilling breakers, common on gently sloping seabeds, encourage broad dispersion of microplastics, notably for smaller-sized particles. Plunging breakers exhibit a similar pattern but with less dispersion and an initial forward movement of neutral and heavy particles. Surging breakers feature minimal dispersion and a distinct oscillatory motion. It has been observed that medium-sized particles with a 1 mm diameter in this work exhibit the most substantial forward movement, likely due to an optimal balance between inertia and viscosity, enabling an effective response to wave momentum. Larger particles, influenced mainly by inertia, tend to show less dispersion and advection. Meanwhile, smaller particles, more affected by viscosity, demonstrate greater dispersion, interacting extensively with wave-induced turbulence. This study reveals the significance of inertia in the behavior of microplastics over slopes, emphasizing the importance of considering inertial effects for precise modeling of microplastic movement in nearshore areas.

Drug compatibility with various closed intravenous infusion containers.

Objective: The aim was to systematically compare the drug compatibility with various closed intravenous (i.v.) infusion containers, to provide a reference for selecting a relatively superior infusion container and improve the medication safety for patients in clinical practice. Methods: The compatibility of four commonly used clinical injections (ceftazidime, pantoprazole sodium, ambroxol hydrochloride, edaravone) with three representative closed i. v. infusion containers (non-PVC infusion bags, upright polypropylene infusion bags, inner sealed polypropylene infusion bags) prefilled with infusion fluids (0.9% sodium chloride or 5% dextrose) in the Chinese market were investigated in this study. The particle counts of both infusion fluids and diluted chemical injections by infusion fluids in various infusion containers were determined by the light obscuration method. At 0, 2 and 6h after four injections following dilution with infusion fluids in each container, the pH of the solutions was detected, and the physical properties were examined by visual inspection. Meanwhile, the drug concentrations were assessed by high performance liquid chromatography (HPLC). Results: As for either infusion fluids or diluted injections by infusion fluids, the particle counts in non-PVC infusion bags were significantly greater than those in the other two bags under some circumstances. The particle counts in diluted injections by infusion fluids increased dramatically compared with those in infusion fluids in all infusion containers, especially for the small-size particles. But pH, physical properties and drug concentrations of diluted infusion solutions in all infusion containers remained nearly unchanged over the test period. Conclusion: Closed i. v. infusion containers included in this study are all well-compatible with four injections. Moreover, the closed infusion containers produced by Chinese manufacturers have met the international quality standard. Particularly, the intravenous admixture preparation process needs to be optimized to reduce the overall particulate contaminants.

Introducing the novel concept of cumulative concentration roses for studying the transport of ultrafine particles from an airport to adjacent residential areas

Abstract. Airports are often surrounded by urban residential areas, which is both a motivation and challenge for studying their potential impact on local air quality. Airports are a relevant source of ultrafine particles (UFPs), which can pose a risk to human health due to their small size (particle diameter Dp≤100 nm). However, in urban environments, UFPs originate from a multitude of biogenic and anthropogenic sources. Here, we investigate UFPs in close proximity to an airport to disentangle their impact on local air quality from other urban sources. We present observations and analyses of airborne UFP concentrations and size distributions determined at two sites in close proximity to Munich Airport. Therefore, two novel measurement stations were established north and south of the airport but were neither situated on the axis of prevailing wind directions nor impacted by fly overs. This set-up allowed us to explore a mainly advection-driven distribution of UFPs into the most populated adjacent residential areas. The observation period covered a full year from August 2021 to July 2022. We analysed the data set in three steps. (1) First, we derived UFP concentration roses using the wind data as reported at 10 m height at the airport to represent the local wind field. An increase in particle number concentrations and a shift of the modal maximum towards smaller mobility diameters became evident for wind directions, including those approaching from the airport. During the airport's operation hours during the daytime, median particle number concentrations were 2.2- and 1.6-fold compared to nighttime at the northern station and the southern station. However, our data had a high variability, and the direction-based analysis was uncertain due to other potential UFP sources in the surroundings and the assumption of a homogeneous, local wind field. (2) Next, we derived concentration roses employing the airflow observations from the two measuring stations at 5.3 m height. While the annual concentration rose in principle yielded the same conclusions as the first analysis step, a significant seasonal and diurnal variability of UFPs and wind became evident. The influencing factors were likely other urban local UFP sources, an increased surface roughness due to green vegetation, and the atmospheric boundary layer development. (3) In order to assess the possible advection of UFPs from the direction of Munich Airport relative to all other directions over the course of the year, we calculated cumulative concentration roses with both local- and site-scale wind data. Under the assumption of a homogeneous local wind field, the fraction of all UFPs sampled in airflows approaching from the airport's direction was 21 % (N322) and 40 % (S229). Considering a local background, the range of UFP advection from Munich Airport to the adjacent residential areas was up to 10 % in the north and 14 % in the south. It has to be noted that these values highlight the relative magnitude of the maximum impact of the airport on local air quality as they do not distinguish between UFP sources from the airport and other measuring sites. Additionally, they integrate over a time period during which the airport did not reach its full capacity compared to pre-COVID-19 times.

The choice of a method for selecting and determining the quantitative and qualitative content of microplastics in wastewater

A general growth in the polymers production and consumption leads to an increase in the new types of wastes. In conjunction with the lack of secondary recycling power this fact is being a reason for appearance of a new processes that is potentially destructive for the environment. In particular, plastic wastes that is being stored in the wastewater of a large cities under a combination of aggressive factors action such as humidity, mechanical and UV-erosion degrades into a small-size particles, famously known as microplastics (MP). The study presented is devoted to the methodology development for acquisition, quantitative and qualitative analysis of wastewater derived microplastics. An experimental part deals with real wastewater samples collected at different infrastructurally-important objects of Rostov-on-Don and Aksai cities. For all the sampling locations the presence of urban-generated MP particles is approved. The results show that the research methods used are able to satisfy the output data quality conditions. However, the significant time and cost consumption of the research chain developed limits its wide practical application.

A COMPUTATIONAL STUDY FOR AIR-€“SOLID PARTICLES FLOW PATTERNS IN RIB-ROUGHENED FLUIDIZED BED VESSELS

This paper includes analysis of the flow of air and solid particles in fluidized bed units using a computational fluid dynamics (CFD) technique. The CFD simulations are carried out with three geometries, one plane vessel and the other two with ribs of square and triangle shape. The results are obtained in terms of velocity, volume fraction distribution, and bed expansion. The effect of other parameters, such as coefficient of restitution, initial bed height, and particle diameter, is also examined. When the particle diameter is large, airflow in an upward direction increases the solid bed height but the flow is almost steady. In the case of small-sized particles, the velocity field and volume fraction profiles for both phases vary with time. In certain regions within the bed, the air becomes concentrated and takes the form of a bubble. The results also show that in fluidized bed units, the unsteady behavior is usually enhanced when ribs are used. The comparison in terms of root mean square values indicates that velocity variation is ~50% more when triangular ribs are used The overall results show that placement of triangle-shaped ribs can be favorable for enhancing momentum and related processes/phenomena in the fluidized bed devices.

Magnetorheological fluids: A comprehensive review

The magnetorheological (MR) fluids contain magnetic micro-sized iron particles, non-magnetic-based fluid, and some additives in order to mitigate sedimentation and agglomeration. The various carrier fluids used in the preparation of MR fluids are mineral oil, silicon oil, castor oil, soybean oil, kerosene, synthetic oils, honge oil, organic oil, water-based oils, etc. However, for obtaining better vibration control, silicone oil is the most preferred one due to its higher viscosity index, lower friction characteristics, higher flash point, and higher shear strength. The MR fluids have various application areas such as dampers, prosthetic knees, valves, brakes, clutches, finishing processes etc. The dampers containing MR fluids are used in automobile cushioning for enhancing passenger comfort and MR suspensions significantly improve steering stability in vehicles. In case of MR brakes, the braking torque on the rotating disks is controlled using the generated shear stress. The carbonyl iron (CI) particles exhibit better rheological characteristics as compared to electrolytic iron (EI) particles. The use of MR fluids produces stable and natural limb movement in orthoses, lower limb prostheses, and exoskeletons. The MR fluids also prove to be very significant in polishing applications. There are various issues with preparation methods and difficulties in the storage of MR fluids. The problems encountered in the synthesis of MR fluids include sedimentation, agglomeration, in-use thickening, corrosion, erosion, etc. The impact of particle proportion, particle shapes, and size has been influential in evaluating MR characteristics. The viscosity and shear stress of MR fluid have been mitigated at higher values of temperature and even CI particles get oxidized at higher temperatures. The CI particles as compared to EI particles are the majority favourable particles used for dispersing state within the MR fluids due to their higher value of saturation magnetization, more availability, and lesser cost. The small-sized particles led to lower wettability, whereas larger-sized particles accounted for an increased sedimentation rate. The currently available MR fluids cost is still on the higher side and the preparation of economical MR fluid is still a big challenge for the researchers. The MR fluids storage is also a big concern. The future scope of MR fluid may be in heavy industries such as nuclear, shipbuilding, oil and gas, space and aviation, etc. to achieve the desired damping response.

Visual detection of microplastics using Raman spectroscopic imaging.

As a new type of pollutant in the marine environment and terrestrial ecosystems, microplastics have attracted widespread attention. Assessing the ecological risk of microplastics relies on accurately detecting small-sized particles in the environment. Microplastics exhibit unique "fingerprint" characteristics in Raman spectroscopy, making them suitable for rapid identification. In this study, we achieved visualization of microplastics through pseudo-color images generated by Raman spectroscopy imaging. Pseudo-color imaging maps were generated by selecting characteristic peaks and the classical least-squares fitting method was used to visually represent the distribution of different microplastics. The study explored the potential of Raman spectroscopy and its mapping mode in distinguishing various types of mixed microplastics and demonstrated that this approach can identify microplastics in complex environmental samples. Specifically, a cloud-point extraction followed by membrane filtration method was successfully applied to identifying mixed-component microplastics. In summary, the category, quantity, location, and differentiation of microplastics can be accurately analyzed by Raman spectroscopy, which provides a basis for assessing their ecological risk.

Natural Green Synthesis of Silver Nanoparticles using Leaf Extract of Guazuma Ulmifolia Lam and Analysis of its Antimicrobial Property

Abstract: In the field of life science, nanoparticles are one of the leading adverse technologies. Here, the particles are seen in nanometers of 1–100 nm. In small-size particles, many useful applications are seen in the fields of medicine, pharma, agriculture, and many more industry sectors. In the present study, Guazuma ulmifolia, a member of the Malvavceae family, was a test plant. In this study, silver nanoparticles were synthesised from plant extract. Characterization using SEM, XRD, FTIR, and UV spectra confirmed the presence of nanoparticles. Silver nanoparticle sizes were measured using SEM, and the sizes ranged from 132nm to 352 nm. The XRD size of silver nanoparticles calculated using Debye-Scherrer’s equation was found to be 15.31 nm. Four drop-down FT-IR peaks were observed, which are 3369.60, 2162.44, 1643.53, and 635.04. N-H and C-I bonds were observed, and UV-Vis nanoparticles synthesised showed maximum absorptions between 300 nm to 700 nm. The sharp bands of silver nitrate nanoparticles were around 535nm for fresh leaves. The antimicrobial activity of synthesised nanoparticles against bacterial test pathogens, viz., Escherichia coli, Salmonella typhi, Bacillus subtilis, and Staphylococcus aureus, showed significant antibacterial activity. The average percentage of inhibition of bacteria is 38.83%, 0%, 10%, and 18.5%. Antifungal activity was also observed against Aspergillus niger, Fusarium oxysporum, Penicillium atramentosum, Aspergillus flavus, and Alternaria solani. The average percentage of inhibition in fungi is 15.68%, 58.53%, 0%, 32%, and 22.2%.

Development of Moisture Absorbent Ceramic-Coated Separators for Advanced Lithium-Ion Batteries

In the present human life, various electric devices and machines are worked by lithium-ion batteries (LIBs). The batteries have still remained challenges such as, the low cycling stability due to side reactions during charge-discharge cycling and the weak thermal stability at high temperatures. Accordingly, research on improving resistance to high temperatures and impregnability by coating ceramic particles and polymer binders on the surface of the separator is being conducted. The ceramic coating separator is manufactured by connecting small-sized inorganic particles to each other using a small amount of binder. The inorganic particles have high hydrophilicity and high specific surface area, so the ceramic separator has excellent wettability to the electrolyte. As a ceramic coating, alumina is currently commercialized, and a slurry is prepared by mixing a binder, etc., and then coated on a separator and then dried. LG Energy Solutions has commercialized a ceramic composite separator called SRS (Safety-reinforcing separator) and is applying it to batteries. By introducing a ceramic layer on the surface of a polyolefin-based separator, the heat resistance and mechanical strength of the separator have been greatly improved, and it has been widely used in high-capacity and large-sized batteries. when the temperature of the LIBs rises and the separator shrinks or ruptures, a large amount of lithium ions may move, making control difficult and creating a risk of explosion. Therefore, shutdown occurs, but a separator with good shape retention at high temperature is required. Accordingly, research on improving resistance to high temperatures by coating ceramic particles and a polymer binder on the surface of the separator is being conducted. In this work, Ceramic-coated separator membrane film was fabricated using aluminum fluoride (AlF3) materials for a powerful moisture (H2O) scavenger. Accordingly, research on improving high temperature resistance and impregnation property by coating ceramic particles and a polymer binder on the surface of the separator is in progress. First of all, a-AlF₃ nanorods with an average length of 1.882 μm and a diameter of 320 nm were synthesized under low supersaturation conditions. Then, PVdF-HFP [Poly(vinylidene fluoride-co-hexafluoropropylene)]-acetone solution was mixed and coated on a polypropylene membrane. The AlF₃-coated separator exhibited thermal shrinkage of 4%, 8%, and 18% at 130, 140, and 150°C, respectively, confirming that thermal stability was improved. In addition, as a result of the impregnation test, it was confirmed that the impregnation property of the coated separator was improved compared to the existing polypropylene separator. In addition, it was confirmed that the full cell manufactured using the a-AlF₃-coated membrane film has improved cycle stability and high-speed, high-capacity compared to the full cell manufactured using the existing non-coated separator.