Large Particles Research Articles

Relationships between HDL subpopulation proteome and HDL function in overweight/obese people with and without coronary heart disease

Background and aimsThe structure-function relationships of high-density lipoprotein (HDL) subpopulations are not well understood. Our aim was to examine the interrelationships between HDL particle proteome and HDL functionality in subjects with and without coronary heart disease (CHD). MethodsWe isolated 5 different HDL subpopulations based on charge, size, and apolipoprotein A1 (APOA1) content from the plasma of 33 overweight/obese CHD patients and 33 age-and body mass index (BMI)-matched CHD-free subjects. We measured the relative molar concentration of HDL-associated proteins by liquid chromatography tandem mass spectrometry (LC-MS/MS) and assessed particle functionality. ResultsWe quantified 110 proteins associated with the 5 APOA1-containing HDL subpopulations. The relative molar concentration of these proteins spanned five orders of magnitude. Only 10 proteins were present in >1% while 73 were present in <0.1% concentration. Only 6 of the 10 most abundant proteins were apolipoproteins. Interestingly, the largest (α-1) and the smallest (preβ-1) HDL particles contained the most diverse proteomes. The protein composition of each HDL subpopulation was altered in CHD cases as compared to controls with the most prominent differences in preβ-1 and α-1 particles. APOA2 concentration was positively correlated with preβ-1 particle functionality (ABCA1-CEC/mg APOA1 in preβ-1) (R2 = 0.42, p = 0.005), while APOE concentration was inversely correlated with large-HDL particle functionality (SRBI-CEC/mg APOA1 in α-1+α-2) (R2 = 0.18, p = 0.01). ConclusionsThe protein composition of the different HDL subpopulations was altered differentially in CHD patients. The functionality of the small and large HDL particles correlated with the protein content of APOA2 and APOE, respectively. Our data indicate that distinct particle subspecies and specific particle associated proteins provide new information about the role of HDL in CHD.

Elucidation of the trigger for trenching around Al6(Fe, Mn) on AA5083 aluminum alloy in diluted synthetic seawater

A small area with a large Al6(Fe, Mn) particle and a large Mg2Si particle was prepared on AA5083, and the dislocation and corrosion behaviors were compared with those of small areas containing only Mg2Si and Al6(Fe, Mn) particles in 100-times diluted synthetic seawater. Mg2Si discolored in both cases upon immersion, but discoloration and trenching were observed for Al6(Fe, Mn) only when Mg2Si was on the same area. The discoloration of Al6(Fe, Mn) started simultaneously with the dissolution of Mg2Si. The role of Mg2Si in the discoloration of Al6(Fe, Mn) particles and the trench formation mechanism was discussed.

Highly dispersed Ni nanoparticles confined in mesoporous SBA-15 for methane dry reforming with improved coke resistance and stability

Methane dry reforming (DRM) is a promising route for sustainable syngas production, in which Ni-based catalysts face challenges of metal sintering and coke formation. In this work, highly dispersed Ni nanoparticles (NPs) embedded in the mesopores of SBA-15 were prepared using a simple solid-state impregnation (SSI) method. TEM and cross-section HRTEM results clearly indicated that ultra-small Ni NPs (3–4 nm) were orderly dispersed within the mesopores of the SBA-15 support. Compared with the conventional wetness impregnation (WI) method, the Ni/SBA-15 catalyst prepared by solid-state impregnation method possessed much better catalytic activity, stability, and coke resistance in DRM. In-situ DRIFTS and semi-in-situ XRD were used to elucidate the dispersion and encapsulation mechanism of Ni within the mesopores of SBA-15 during the sample preparation process. Specifically, WI formed large NiO particles, while SSI formed smaller NiO NPs with stronger interaction between metal and support (SIMS) via forming Ni-O-Si species which is beneficial for the DRM reactivity. This work establishes relationships among catalyst preparation, structure, and DRM performance, paving the way for general template-assisted methods to prepare nanometallic catalysts for various applications.

Enhancement in Formation of Insoluble Arsenic Phases without Re-Leaching by Particle Size of Excavated Sediment with Iron Sulfate Heptahydrate

ABSTRACT Massive quantities of naturally arsenic-containing sediments are excavated for construction. Chemical immobilization is applied to such excavated materials for reuse. Appropriate physicochemical properties should be understood to enhance the formation of the insoluble arsenic phases without re-leaching. The up-flow column retention test flowing 10 mg L−1 of arsenic solution was conducted to understand how the retention of arsenic and the phases of arsenic immobilized by iron sulfate heptahydrate depend on the particle size of the excavated sediment. The amount of arsenic retained on the immobilization material (particle size of 0.5 mm) during the retention test was lower for the larger particle size of the excavated sediment. However, arsenic was more stably retained on the immobilization material for the large particle sizes (1.0–2.0 and 2.0–5.0 mm) and the amount of arsenic re-leached was 12% of that in the small one (<0.5 mm). The percentages of arsenic in fraction 3 of sequential extraction increased from 45% to 68% with increasing the particle size. These results indicate that the excavated sediment with a larger particle size than that of immobilization material retains less arsenic on the immobilization material, but the arsenic phases immobilized are more stable, resulting in less arsenic re-leaching. This study suggests that the use of excavated sediment with a particle size larger than that of the immobilization material is desirable for the application of immobilization technique without re-leaching.

Experimental study on the critical flow velocity for sand production in shale gas wells

The purpose of this study is to determine the critical flow velocity for the sand production of shale gas wells under different conditions through experiments and to predict the sand production of gas wells. The experiment is based on the API fracture diversion experimental device. To study the influence of shale physical properties on sand production, a shale rock plate was used as the propped material in the API fracture conductivity experiment. The results show that when the closure pressure exceeds the critical fracture point of shale, the critical flow velocity for sand production will decrease on a large scale. A proppant with a large particle size is helpful for maintaining fracture opening, and the critical sand production velocity is greater. The higher the viscosity of the fluid is, the lower the critical sand production velocity. This paper provides a reference method for determining the critical sand production velocity in shale gas wells.

The Effect of Silicon Nanoparticle Size on Cycle and Calendar Life

Lithium-ion batteries are now ubiquitous in modern electronics, electric vehicles, and many other applications. As the battery industry continues to push for better, longer lasting batteries, many have turned to using a different anode material that would provide higher-energy density and require less frequent charges. While graphite is the tried-and-true anode material for lithium-ion batteries, a silicon anode battery could provide up to ten times higher theoretical energy density than graphite. However, there are a lot of challenges standing in the way between silicon anode batteries and commercialization—the large volume expansion of silicon (around 200-300% expansion, compared to graphite at 10%) and the unstable solid-electrolyte-interface (SEI) of silicon results in anodes that mechanically degrade and calendar age faster than their graphite counterparts.Previous research has demonstrated that plasma-enhanced chemical vapor deposition (PECVD) silicon nanoparticles with a hydrophilic coating such as polyethylene oxide (PEO) results in silicon anodes with good cycle life [1, 2, 3, 4]. In this system, smaller particle sizes typically yielded better cyclability than larger particle sizes, which is contrary to conventional wisdom that more surface area is detrimental as it allows for more SEI formation and side reactions. However, since silicon anodes experience large volume changes during cycling, the surface area might not be the dominant contribution to capacity fade. Larger silicon particles result in larger total expansions of the electrode, which causes more mechanical damage like cracks to form, exposing fresh surface area to electrolyte and SEI formation.This research investigates the performances of PEO-coated PECVD Si electrodes with nanoparticles ranging from 3 to 27 nm in diameter. We measure the cycle life at a rate of 0.333C, as well as the calendar lifetimes of each electrode. We characterize each electrode with SEM imaging, tortuosity measurements, and electrochemical impedance spectroscopy to understand the differences in microstructure that contribute to capacity fade and impedance rise.

Evaluation of Nickel-Iron (Oxy)Hydroxide Catalysts in Varied Electrode Geometries Under Industrially Realistic Conditions for Enhanced Alkaline Water Electrolysis

In pursuit of realizing a hydrogen-based economy, the challenge lies in enhancing the efficiency of crucial water electrolysis technologies. Alkaline water electrolysis (AWE) holds promise as an ecologically friendly method for H2 production, primarily due to its capacity for employing non-precious metals as electrocatalysts, in contrast to more costly options which can only switch to noble metals such as ruthenium or iridium. However, this technology faces a significant challenge arising from the sluggish kinetics of the oxygen evolution reaction (OER), which constrains the overall efficiency. [1] Furthermore, the limited stability of many OER catalysts alternatives developed at lab scale and less harsh conditions poses a substantial obstacle to the commercialization of this technology.[2] To overcome this issue, the development of highly active OER catalysts that maintain their activity under industrial conditions is of major importance explaining the growing attention that this topic is gaining in literature. Nevertheless, most of the reported systems are tested at low current densities under easily manageable conditions in the laboratory (≤ 100 mA cm-2, 1 M KOH, RT). Without disagreeing that this approach is necessary to identify promising options among the numerous catalyst systems, it is not sufficient when competing with existing technologies that already achieve high current densities. In this context, we investigate a low-cost, abundantly available non-precious metal based OER-catalyst under industrially relevant conditions (≤ 1.2 A cm-2, 30 wt.-% KOH, 80 °C). The synthesis is based on a multistep galvanic deposition method introduced by Wu et al [3], receiving a highly porous NiFeOOH catalyst. Addressing the complexity of the multiphase process of AWE that involves gas-liquid-solid interfaces, the catalyst system is transferred to numerous nickel electrodes with different 3D geometries (plain woven mesh, knitted mesh, expanded metal mesh) for the investigation of their impact on bubble formation and detachment. To further optimize the catalyst system a variation of the iron content with respect to its’ molar fraction relatively to nickel has been carried out from x(Fe)=0 to x(Fe)=0.75, which after synthesis were first examined using SEM and EDS. The structure can be considered as pompom-shaped particles, forming a porous framework, as can be seen exemplarily in Figure 1a) on a knitted nickel-wire mesh coated with NiFeOOH. Observing variations in iron content, it becomes evident that a higher iron content results in larger particle sizes, thereby altering pore sizes. However, the surface morphologies of each catalyst until a molar fraction x(Fe)=0.5 is reached, can be considered as very similar. When comparing the SEM images of the mesh with a molar fraction x(Fe)=0.75 to the other molar fractions, a secondary phase becomes apparent on the surface. Notably, the porous structure persists within the crystalline phase. It could be shown by EDS that the target values for the molar fractions set in the galvanic bath and the actual molar fractions nearly show no deviations. Further, a uniform dispersion of Ni, Fe and O is observed.The electrochemical investigation of the prepared catalysts was done in a 3-electrode PTFE beaker cell setup in 30 wt % KOH and at 80 °C. The measurement protocol we introduce consists of galvanostatic steps between 0-1.2 A cm-2. The stability is tested chronopotentiometrically as well by maintaining a current density of 500 mA cm-2 for 100 h. It becomes apparent that no optimum is reached in the tested range of iron content and that the potential continues to drop as the molar fraction of Fe increases, achieving the lowest potential with 1.38 V vs. RHE at 50 mA cm-2 and 1.42 V vs. RHE at 750 mA cm-2 with x(Fe)=0.75. It could be further proved that the NiFeOOH catalyst with x(Fe)=0.75 is a highly stable catalyst, resulting in a potential increase of 27 mV over 100 h of testing at 500 mA cm-2, making it to an appropriate OER catalyst for the application in the AWE. The highly porous structure is maintained after testing, proved by SEM imaging. The iron contents after testing are also very similar, which means that there is almost no iron loss in the coating. For the different tested electrode geometries coated with NiFeOOH (x(Fe)=0.5), similar activity is observed, shown in Figure 1b) with a ranging potential between 1.38 V to 1.41 V vs. RHE at 50 mA cm-2 and 1.42 V to 1.45 V vs. RHE at 750 mA cm-2.[1] a) Cao et al., Energy Environ. Sci. 2012 b) Zhao et al., ACS Chemical Reviews 2023.[2] Zeng et al., Journal of Energy Chemistry 2022.[3] Wu et al., Applied Surface Science 2021. Figure 1

Experimental study on the ash deposition and NO emission of high-alkali coal under the staged O2/CO2 and O2/RFG conditions

The oxy-fuel combustion contributes to carbon capture, while the recirculation of flue gas brings about high concentrations of SO2 and H2O, which can affect the transformation of minerals in high-alkali coal. The staged oxy-fuel combustion, as an effective method for NOx reduction, can also change the ash deposition behavior of high-alkali coal. Two kinds of diluting agents, including pure CO2 for O2/CO2 combustion and simulated “recycled flue gas” (CO2, SO2, and H2O) for O2/RFG combustion, were employed in the present work. The ash deposition and NO emission of high-alkali coal during the staged oxy-fuel combustion were simultaneously studied under O2/CO2 and O2/RFG conditions. The conversion ratios of fuel-nitrogen to NO (CNO) and ash deposition efficiencies (Ed) at different stoichiometric ratios in primary combustion zone (SR1) and different oxygen concentrations were obtained. Afterwards, a series of tests were performed to further analyze the ash deposits. The experimental results show that as SR1 increases from 0.6 to 1.2, CNO jumps from 2.0 % to 23.5 % (O2/CO2 combustion) and from 1.9 % to 19.9 % (O2/RFG combustion). The additions of SO2 and H2O can reduce the NO emission. With the rising SR1, Ed under the O2/CO2 and O2/RFG conditions decreases from 4.0 % to 2.6 % and from 4.8 % to 2.1 %, respectively. At high SR1, the CaSO4 amount declines and the iron contributes less to the ash deposition. In O2/RFG combustion, the small sticky particles of sodium aluminosilicates on large particle surfaces reduce, and the large particles of calcium aluminosilicates shrink because some calcium produces CaSO4. Moreover, the exposure of ferrous iron to H2O helps its oxidization so iron is harder to cause severe adhesion. As O2 concentration rises from 21 % to 40 %, CNO shows an upward trend. Meanwhile, Ed under the O2/CO2 and O2/RFG conditions increases from 2.6 % to 3.7 % and from 2.3 % to 2.7 %, respectively. The present work is expected to provide some conducive information for the clean utilization of high-alkali coal and secure operation of boiler, as well as large-scale CO2 capture.

Influence of Microstructure on Defect Chemistry - Transport - Chemical Strain Coupling of (Pr,Ce)O2-δ Nanoparticles

Solid oxide fuel/electrolysis cells (SOFC/SOECs) are promising and environmentally-friendly technologies for meeting ever-increasing electricity and energy storage demands. Nanostructuring of SOFC/SOEC electrodes can enable improvement of the reaction kinetics and reduction of the operating temperature, owing to factors including the enlarged surface area, short diffusion lengths, and unique surface & interface properties. While the kinetic benefit is apparent, the effect of nanostructuring on other device-relevant physico-chemical properties cannot be neglected. Especially, the coefficients of chemical expansion (CCEs) are an important metric for mixed ionic-electronic conductors that can undergo changes in oxygen stoichiometry with variations in the surrounding atmosphere, temperature, and voltages during processing/operation. Chemical strains can cause cracking of monolithic parts during fabrication and delamination of electrodes from electrolytes in operation. CCEs are typically measured on bulk, polycrystalline materials with large particle or grain sizes. Therefore, it is important to understand the coupled transport and chemical expansion behavior in nano-ionic materials with large interface/surface density. This work aims to uncover the role of microstructure and nanoscale effects on the chemical strain and transport properties, through the lens of defect chemistry, with the goal of ultimately developing design principles for zero-strain materials with improved device lifetime and performance.Pr0.2Ce0.8O2- δ (PCO20) was selected as a model system and prepared as nanoparticles by a surfactant-free, low temperature co-precipitation method. (Pr,Ce)O2-δ compositions are valuable model oxide ion conductors to study, since both Pr and Ce can undergo changes of valence states under different temperature and pO2 regimes to accommodate oxygen stoichiometry excursions. Prepared nanoparticle samples were first in-situ sintered in the dilatometer at three different temperatures (600 ⁰C, 725 ⁰C, 850 ⁰C) to induce and evaluate microstructure evolution. The chemical strain and electronic/ionic conductivity were then studied on stable microstructures with different average particle sizes at lower temperatures by simultaneous in-situ dilatometry and electrochemical impedance measurement (EIS) upon changing pO2 at different isotherms (550 to 400 ⁰C). At each isotherm, all the samples expand as pO2 decreases. From the conductivity vs. pO2 measurements, the maxima at certain pO2 indicate the dominant polaron mechanism of the electronic transport, consistent with the measured conductivity activation energy. However, samples with lower sintering temperatures exhibit less pO2 dependence of the conductivity, which implies a transition in the mixed ionic/electronic conduction behavior toward higher ionic transference numbers as particle size decreases. Correspondingly, the chemical strains associated with losing oxygen monotonically decrease with the decrease of the sintering temperature, and hence the particle size. The chemical strain vs. oxygen stoichiometry dependence and corresponding CCEs were quantified as function of particle size and temperature by combining thermogravimetric analysis (TGA) with the dilatometry results and in-situ X-ray diffraction. The particle size, chemical composition, valence states, and morphology of samples after CCEs measurements were also compared using XRD, SEM, and S/TEM-EELS, with the latter indicating the expected differences between bulk and surface defect chemistry. Implications of the results for size-dependent defect chemistry and its influence on chemical strains and redox CCEs will be further discussed. Keywords: redox, chemical expansion, defect chemistry, mixed ionic electronic conduction, ceria, chemo-mechanics, nanoparticle, thermogravimetric analysis, dilatometry, impedance

Effect of four different cooking methods on the fat digestion characteristics of yellow-feathered chicken

The aim of this study was to investigate the effects of four cooking methods (boiling, microwaving, air frying and roasting) on the fat characteristics of chicken. The results showed that cooking significantly exacerbated fat oxidation, with boiling showing significantly lower level of malondialdehyde (MDA) at 0.25 ug/g. Microwaving, air frying and roasting significantly increased the levels of saturated fatty acids (SFA), while boiling decreased the levels to 1137.24 µg/g. In terms of digestive characteristics, in the gastric digestive fluid, the roast group had the largest particles while the boil group had the smallest particles. In the intestinal digestive fluid, boiled and microwaved chicken exhibited significantly smaller particle sizes, which was consistent with the trends in lipid droplet size and number observed by laser confocal. Boiling and microwaving significantly increased digestibility, reaching 51.51% and 54.25%, respectively. In conclusion, boiling could slow fat oxidation and reduce particle size, and promote lipid digestion.

One-Dimensional Van Der Waals V2Se9 As a Conversion-Type Anode Material for Advanced Li Rechargeable Batteries

Volume expansion of active materials during lithium storage is one of the main issues in Li-ion batteries (LIBs) that should be addressed. In particular, large volume changes and particle cracking are problematic for electrode materials based on conversion reaction, which are considered attractive anode materials with high energy densities. In this study, a one-dimensional van der Waals (1D vdW) material, V2Se9, is proposed as a conversion-type anode material for LIBs. The V2Se9 electrode material has a 1D chain molecular structure with vdW interactions between chains to form a bulk crystal structure. The spaces between the 1D chains act as structural buffers and provide short Li+ diffusion paths that can improve the electrochemical performance of the electrode materials. The V2Se9 electrode exhibits a high reversible capacity of 563.3 mAh g-1 at 100 mA g-1 and a high rate capability of 109.1 mAh g-1 at 3200 mA g-1. The capacity retention of V2Se9 electrodes is 83.72 % after 100 cycles. Synchrotron X-ray diffraction and X-ray absorption spectroscopy reveal the formation of Li2Se and V metal, indicating that Li ion storage occurs via the conversion reaction. The structural stability of V2Se9 is demonstrated using SEM measurements of the discharged and charged V2Se9 electrodes during cycling. These results demonstrate the reaction mechanism of V2Se9 and highlight the potential of 1D vdW materials as high-performance anode materials in LIBs.

Quantifying Aging-Induced Irreversible Volume Change of Porous Electrodes

Automotive manufacturers are working to improve cell and pack design by increasing their performance, durability, and range. One of the critical factors to consider as the industry moves towards materials with higher energy density is the ability to consider the irreversible volume change characteristic of the accelerated SEI layer growth tied to the large volume change and particle cracking typically associated with active material strain. Here, we add to a previously developed mechano-electrochemical model[1-8] to more practically understand the impact of irreversible volume change, primarily assigned to SEI layer growth. As the time from initial design to manufacture of electric vehicle is decreased in order to rapidly respond to consumer demands and widespread adoption of electric vehicles, the ability to link aging and volume change to end of life vehicle requirements using virtual tools is critical.[9] In this study[10], we apply a model to determine the irreversible volume change at the electrode and cell level, allowing for virtual design iterations to predict the volume change at battery cell aged states, and probe possible changes in the SEI layer over life.

Scalable One-Pot Synthesis of Nanostructured P2-Type Na2/3Ni1/3Mn2/3O2 Cathode Material for High-Performance Na-Ion Batteries

Sodium-ion batteries (SIBs) based on sodium transition metal oxides are considered as a viable alternative to lithium-ion batteries (LIBs) for grid-scale energy storage. This is because the critical elements used in these SIBs, such as sodium, manganese, and nickel, are abundantly available, and their supply chain does not pose any geopolitical risk like lithium and cobalt used in common LIB cathodes.1 Among sodium transition metal oxide cathodes, the P2-type Na2/3[Ni1/3Mn2/3]O2 (NNMO) is a promising material due to its high operating voltage (up to 4.5 V vs Na/Na+) and high capacity. When cycled between 2-4.5 V vs Na/Na+, it has a capacity of 173 mAh/g.2 This combination of high operating voltage and high capacity allows NNMO to outperform common LIBs in terms of energy density. Therefore, SIBs based on NNMO cathode are a scalable alternative to LIBs.Unfortunately, the current method used to produce NNMO through solid-state conversion is a time and energy-intensive process. It requires a temperature above 800 degrees Celsius and takes at least 12 hours to make a single batch of NNMO. Moreover, NNMO formed using this method has large particle sizes of a few micrometers. In my presentation, I will introduce a new and highly scalable method for synthesizing NNMO. This method can create NNMO in less than 20 minutes, which is much faster than the usual 12+ hours required by existing methods. Additionally, our protocol produces Nano-NNMO particles with size in the sub-200 nm. Nanoscale NNMO is crucial because it enhances the electrochemical performance of the materials, which I will also discuss. Key words: Sodium-ion batteries, Na2/3[Ni1/3Mn2/3]O2, high capacity, nanoparticles, rapid synthesis. References (1) Wang, C.; Liu, L.; Zhao, S.; Liu, Y.; Yang, Y.; Yu, H.; Lee, S.; Lee, G.-H.; Kang, Y.-M.; Liu, R.; et al. Tuning local chemistry of P2 layered-oxide cathode for high energy and long cycles of sodium-ion battery. Nature Communications 2021, 12 (1), 2256. DOI: 10.1038/s41467-021-22523-3.(2) Zhang, J.; Wang, W.; Wang, W.; Wang, S.; Li, B. Comprehensive Review of P2-Type Na2/3Ni1/3Mn2/3O2, a Potential Cathode for Practical Application of Na-Ion Batteries. ACS Applied Materials & Interfaces 2019, 11 (25), 22051-22066. DOI: 10.1021/acsami.9b03937.

Total Holographic Characterization of Large Particle Contaminants in Chemical Mechanical Polishing (CMP) Slurries

Nanoparticle slurries are widely used in semiconductor CMP processing. Accurately evaluating quality attributes of CMP slurries can be challenging for standard optical methods. Ceria slurries can be too optically dense and inhomogeneous for most optical measurements. Diluting the slurry can induce agglomeration or break up the agglomerates already present in the slurry. Previous studies of silica CMP slurries demonstrated that Total Holographic Characterization (THC) is effective for monitoring agglomeration in slurries. THC uses particle holograms to determine particle size and composition. Ceria nanoparticles have higher refractive indexes than silica nanoparticles, and produce more scattered light, which can reduce the signal of measurements of agglomerates, making accurate, reproducible measurements more challenging. Ceria slurry was successfully analyzed at concentrations typically used in semiconductor processing. Effective-medium theory is used to understand the variation in refractive index of large particle contaminants as compared to native slurry nanoparticles and other contaminants such as pad debris.

Mitigating the Corrosion of Anodized 304 and 316 Stainless Steel with GOx/PEDOT Coating for Bioelectrochemical Saline Water Applications

Steels are the most used alloys worldwide as they have superior mechanical properties, such as ductility and elasticity. Stainless steel (SS) is used far and wide from infrastructure, households, vehicles, surgical equipment, and medical implants, to electrochemical applications such as supercapacitors, fuel cells, lithium-ion batteries, aqueous rechargeable batteries, and bioelectrochemical systems (BES)1 such as microbial fuel cells (MFCs)2 and microbial electrolysis cells (MECs)3. Even though oxidized stainless steel is a very effective electrode material for BES, it has a high risk of corrosion due to the removal of the protective Cr-based passive oxide layer4.Hereby, this research aims to investigate the corrosion behavior of anodized stainless steel (SS) 304 and 316 mesh in saline water for potential use in BES with high salinity and try to mitigate that corrosion behavior using biocompatible materials. The tested electrodes include SS304 and SS316 mesh before and after anodization (anodized SS, AN-SS), in comparison to AN-SS coated with double layers of graphene oxide (GOx) and poly(3,4-ethylenedioxythiophene) (PEDOT). SS 304 and 316 were anodized using selective leaching protocol to enhance the removal of the bioincompatible and insulating Cr-based layer. The removal of that layer makes SS more susceptible to dissolution and hence further protection is needed. Both GOx and PEDOT were selected to enhance the surface conductivity, biocompatibility, and corrosion resistance. GOx was synthesized using the electro-exfoliation of a graphite sheet at a constant voltage of 10.0 V in terephthalic acid + NaOH solution, followed by centrifuging at 3000 rpm to remove the large particles.5 After several cycles of washing, the freeze-dried GOx was mixed with Nafion for ink preparation, which was used to coat the An-SS using the spray coating method. The coated electrode was further covered with a PEDOT layer, using the chronpotentiometry electropolymerization method (2 mA/cm2, for 10, 30, or 60 min). Several characterization techniques such as SEM, EDX, XPS, FT-IT, Raman spectroscopy, XRD, and TEM, were used to characterize the physical and chemical structure of the coating materials and the the fabricated electrodes. The corrosion behavior was evaluated using potentiodynamic and potentiostatic methods. Based on the anodic polarization results, the corrosion, passivation, and breakdown (due to dissolution) regions were identified. In this presentation, the corrosion behavior (Ecorr, Icorr, breakdown potential, etc) of the studied electrodes will be correlated with their chemical and physical structures. References K.-B. Pu, J.-R. Bai, Q.-Y. Chen, and Y.-H. Wang, in Novel Catalyst Materials for Bioelectrochemical Systems: Fundamentals and Applications, ACS Symposium Series., vol. 1342, p. 165–184, American Chemical Society (2020) https://doi.org/10.1021/bk-2020-1342.ch008.A. A. Abbas, H. H. Farrag, E. El-Sawy, and N. K. Allam, Journal of Cleaner Production, 285, 124816 (2021).Y. Zhang, M. D. Merrill, and B. E. Logan, International Journal of Hydrogen Energy, 35, 12020–12028 (2010).P. Ledezma, B. C. Donose, S. Freguia, and J. Keller, Electrochimica Acta, 158, 356–360 (2015).H. S. Wang et al., Green Chem., 20, 1306–1315 (2018).

Decoupled cycling of particulate cadmium and phosphorus in the subtropical Northwest Pacific

AbstractWe examined the spatial variation in size‐fractionated (0.8–51 and &gt; 51 μm) particulate cadmium (Cd) and phosphorus (P) based on a large dataset collected during a GEOTRACES Section cruise (GP09) in the North Pacific Subtropical Gyre (NPSG) to better understand the interrelationship between Cd and P biogeochemical cycles. Concentrations of particulate Cd (0.06–2.15 pmol L−1) and P (0.33–10.19 nmol L−1) showed an initial increase with depth followed by a decrease, and were among the lowest observed in the global ocean. Bulk particulate Cd : P ratios in the euphotic zone, indicative of phytoplankton Cd assimilation, showed strong geographic variability averaging 0.05 ± 0.02 within the NPSG interior vs. 0.14 ± 0.04 pmol nmol−1 at the southern boundary. Cadmium to P remineralization ratio in the mesopelagic zone had a roughly similar stoichiometry as what was produced in the euphotic zone, being ~ 0.05 ± 0.01 in the NPSG interior vs. 0.21 ± 0.04 pmol nmol−1 at the southern boundary. Cd–P decoupling was reflected in the elements' vertical distribution, showing unsynchronized changes through the water column, consistent with Cd–P differential remineralization resulting from multiple Cd and P pools. The Cd–P relationship also differed between small and large particles, suggesting differences in Cd assimilation among phytoplankton assemblages as well as particle dynamic processes. Our results highlight complex processes fractionating Cd from P in the oligotrophic ocean and complicate the use of Cd as a palaeo‐phosphate proxy.

Co-bioaugmentation with microalgae and probiotic bacteria: Sustainable solutions for upcycling of aquaculture wastewater and agricultural residues into microbial-rice bran complexes

Aquaculture farming generates a significant amount of wastewater, which has prompted the development of creative bioprocesses to improve wastewater treatment and bioresource recovery. One promising method of achieving these aims is to directly recycle pollutants into microbe-rice bran complexes, which is an economical and efficient technique for wastewater treatment that uses synergetic interactions between algae and bacteria. This study explores novel bioaugmentation as a promising strategy for efficiently forming microbial-rice bran complexes in unsterilized aquaculture wastewater enriched with agricultural residues (molasses and rice bran). Results found that rice bran serves a dual role, acting as both an alternative nutrient source and a biomass support for microalgae and bacteria. Co-bioaugmentation, involving the addition of probiotic bacteria (Bacillus syntrophic consortia) and microalgae consortiums (Tetradesmus dimorphus and Chlorella sp.) to an existing microbial community, led to a remarkable 5-fold increase in microbial-rice bran complex yields compared to the non-bioaugmentation approach. This method provided the most compact biofloc structure (0.50 g/L) and a large particle diameter (404 μm). Co-bioaugmentation significantly boosts the synthesis of extracellular polymeric substances, comprising proteins at 6.5 g/L and polysaccharides at 0.28 g/L. Chlorophyta, comprising 80% of the total algal phylum, and Proteobacteria, comprising 51% of the total bacterial phylum, are emerging as dominant species. These microorganisms play a crucial role in waste and wastewater treatment, as well as in the formation of microbial-rice bran complexes that could serve as an alternative aquaculture feed. This approach prompted changes in both microbial community structure and nutrient cycling processes, as well as water quality. These findings provide valuable insights into the transformative effects of bioaugmentation on the development of microbial-rice bran complexes, offering potential applications in bioprocesses for waste and wastewater management.

Optimization of surface filtration to enhance wafer uniformity by removing large particle in ceria slurry

Owing to the limitations of scaling down, the development of complex structures for chip design is progressing in the semiconductor industry. As a result, the chemical mechanical polishing (CMP) process has become essential for the precise control of micro-level steps and for maintaining surface uniformity between layers during the stacking process. Structural management and improved performance of the consumables used in CMP processes are required. In particular, controlling the abrasive particles in the slurry that directly contact the wafer surface is crucial. Large particles within the slurry can occur scratches and cause non-uniformity in the polishing process, thus the particle size distribution of the slurry must be regulated. In this study, two types of filtration systems were constructed to determine the optimal conditions for CMP of ceria slurry. Depth filtration effectively removes particles through a cake layer formation mechanism but has limitations in achieving a consistent pore size within the fiber layer. Consequently, separation efficiency for particle sizes is relatively low. In contrast, surface filtration consisting of a single membrane demonstrates a consistent correlation between pore size and the size of the filtered particles, resulting in high particle removal efficiency. The pore size capable of removing large particles without active particle loss was 200 nm. After evaluating slurry productivity and filter-induced agglomeration, 0.8 L per minute (LPM) was identified as the optimal flow rate. Additionally, after filtration at 0.8 LPM, the maximum reduction in removal rates was relatively small at 272.54 Å/min due to decreased edge removal rates. However, by removing large particles to implement a monodisperse state, an improvement in uniformity of 17.11 % was achieved. Therefore, the CMP performance can be enhanced using surface filtration to control the particle size distribution (PSD).

Optimising corn (Zea mays) cob powder as an effective sorbent for diverse gel matrices: exploring particle size and powder concentration effects

SummaryThis study aims to valorise a plant waste, corn cobs (Zea mays) enriched with fibres (cellulose of 19.09–19.18% and hemicellulose of 34.04–60.13%), to create gel‐like sorbents. Corn cobs (CB) were dried, grounded and sieved to obtain 500, 250 and 125 μm powder size fractions. Various CB powder concentrations (10–40% w/w) were mixed with distilled water and rice bran oil for 2 min at ambient temperature to form hydrogel‐like and oleogel‐like sorbents, respectively. Visual appearance indicated that selected gels formed by 250 and 125 μm CB powders were self‐sustained right after mixing, while the largest particles (500 μm) could not fabricate gels at the CB concentrations studied. FTIR results suggested that the gelation process was primarily attributed to physical absorption rather than chemical binding. Comprehensive analyses of microstructure, physicochemical properties and rheological behaviour indicated that gelation was due to fibre–fibre interaction (125 μm) and oil/water–fibre interaction (250 μm). An increase in CB powder concentration enhanced the microstructural density and hardness of gels. Thus, 250 μm particles and higher absorbent concentrations resulted in brittle sorbents characterised by high hardness but low cohesiveness. The 250 μm particles also exhibit a superior antioxidant profile and lower oil/water loss than the 125 μm CB particles due to effective intra‐particle trapping mechanisms.

Influence of Graphene Oxide Concentration and Ultrasonication Energy on Fracture Behavior of Nano-Reinforced Cement Pastes

The aim of this study is twofold. First, to assess the effect of the sonication process on the optimal dispersion of GO sheets for nanostructural reinforcement of cement pastes, as there is currently no clear criterion on this effect in the literature. For this purpose, in the first stage, the GO content in distilled water was fixed at 0.03% by weight, and the sheets were dispersed using different levels of ultrasonic energy, ranging from 0 J/mL to 2582 J/mL. In the second stage, to analyze the modification of pore structure due to the addition of GO sheets in different ratios (0–0.06% by weight) and its relationship with the mechanical and fracture properties of reinforced cement pastes. According to the results, it has been determined that the incorporation of GO sheets into the matrix alters the mechanical and fracture behavior, varying depending on matrix pore size and GO particle size. The addition of GO leads to a reduction in the average size of macropores (greater than 8 µm) of 13% for a dosage of 0.45% in weight and micropores (between 8 and 0.5 µm) in a 64% for the same composition with non-sonicated GO, although the total volume of pores in these ranges only decreased slightly. This reduction is more pronounced when the GO has not been sonicated and has larger particle size. Sonicated GO primarily modifies the range of capillary pores (&lt;0.5 µm). The addition of GO with the highest degree of dispersion (465 nm) did not show significant improvements in compressive strength or Young’s modulus, as the cement used contains a significant volume of macropores that are not substantially reduced in any composition. Adding 0.030% ultrasonicated GO achieved a 7.8% increase in fracture energy, while an addition of 0.045% resulted in a 13.3% decrease in characteristic length, primarily due to the effect of capillary and micropores.