Particle Size Determination Research Articles

Green Synthesis of silver nanoparticles from clematis gouriana leaf extract: Physicochemical characterization and antibacterial activity determination for treatment of blood stream infections

BackgroundThe global incidence of bloodstream infections (BSIs) is rising, necessitating the development of effective therapeutic strategies to achieve complete eradication. This study focuses on the synthesis of silver nanoparticles (AgNPs) functionalized with Clematis gouriana extract (CG) (CG-AgNPs) as a potential alternative to conventional treatments for combating BSIs caused by bacterial pathogens. MethodsAgNPs were synthesized by reducing silver nitrate (AgNO₃) using CG extract. The formation of CG-AgNPs was confirmed through UV-Vis spectroscopy, while their characterization included the determination of mean particle size and zeta potential. Elemental composition was analyzed using energy-dispersive X-ray (EDX) spectroscopy. The in vitro antibacterial efficacy of CG-AgNPs was assessed through multiple assays, including a time-kill assay, a film bioadhesion assay, and measurement of reactive oxygen species (ROS) generation. ResultsSPR (surface plasmon resonance) has been employed to validate the development of AgNPs by observing a colour shift to dark brown. The mean particle size and zeta potential of the CG-AgNPs were found to be 38 ± 2nm (PDI 0.104 ± 0.03) and -31.2 ± 1.4mV, respectively. Additionally, E-XRD results show that the prepared AgNPs comply with the silver presence. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the CG-AgNPs against Staphylococcus aureus (S. aureus) were observed to be 6.25 ± 0.8µg/mL and 13.5 ± 2.4µg/mL, respectively.Similarly, the MIC and MBC of CG-AgNPs against Escherichia coli (E. coli) were found to be 13.5 ± 1.5μg/mL and 26 ± 2.8μg/mL, respectively. CG-AgNPs also prevented biofilm formation and bacterial adhesion in a dose-dependent manner; 100% inhibition was achieved in 48h at MBC. In addition, CG-AgNPs remarkably escalated the ROS level within cells, indicating their mechanism of antimicarobial activity. ConclusionsThe findings of this study demonstrate that CG-AgNPs synthesized via green synthesis exhibit significant antibacterial activity, highlighting their potential as an effective alternative for the treatment of BSIs. However, further in vivo studies are required to optimize a suitable dosage form and validate their therapeutic efficacy against bacterial infections in clinical settings.

Optimization of docetaxel-loaded cholesterol nanostructured lipid carriers for improving cancer treatment using Taguchi experimental design

Today's diets boost breast, head, neck, ovarian, and lung cancer risk. This has prompted researchers to study active compounds against these slow killers. Docetaxel (DTX) loaded onto cholesterol nanostructured lipid carriers (NLCs) with elaidic acid appears promising. Carriers were made using solvent emulsification-diffusion. This study used Taguchi's experimental design and analysis with the L16 orthogonal array. The design was utilised to analyse NLC particle size and zeta potential data. These trials considered process factors like elaidic acid percentage (15–30 %), emulsifier concentration (1–4 %), agitation duration (2–8 min), and blending speed (800–1400 rpm). Controlled experimental design plays an important role in pharmaceutical research, as does the privilege of a comprehensive technique aimed to maximize the creation of NLCs loaded with DTX for cancer treatment. Blending speed had a substantial influence on particle size, as the lowest and maximum particle sizes were 170.54 and 190.90 nm. In the zeta potential research, values ranged from 5.88 to 30.72 mV. These data show how important blending speed is in determining particle size. This research supports the sustainable development goals of 3, 9, 12, and 17.

Double refractive particle tracking and sizing

We present a novel bifocal imaging method enabling three-dimensional particle tracking and size determination employing a single camera only. The method is based on double refraction causing a particle to be imaged twice, each particle image of different blur. From these double images, a linear calibration function can be derived allowing to determine the three-dimensional particle position unambiguously over the entire depth of measurement volume. As this calibration function is independent of the particle size used, the particle size can be determined simultaneously by relating size of the double images and depth position of the particle. To prove the applicability, a co-laminar flow of two particle suspensions with particles of 1.14 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m and 2.47 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m in diameter was measured in a Y-shaped microchannel. While the laminar flow field was measured with very low uncertainty and independent of the particle size, the particle size distributions determined reproduced reliably the size distributions expected for the co-laminar flow applied, with a precision of about 98.6 %\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} regarding the particle size discrimination. The progress for research is a new method readily to implement in common optical setups, promising, for example, valuable insights in polydisperse suspension flows—the vast majority of flows in fundamental research and applications.Graphical abstract

Application of Bidimensional Empirical Mode Decomposition for Particle Identification and Size Determination

Application of Bidimensional Empirical Mode Decomposition for Particle Identification and Size Determination

Diffusive micromixing combined with dynamic in situ laser scattering allows shedding light on lipid nanoparticle precipitation

Pharmaceutical formulations are increasingly based on drug nanoparticles or carrier nanoparticles encapsulating drugs or mRNA molecules. Sizes and monodispersity of the nanoparticles regulate bioavailability, pharmacokinetics and pharmacology. Microfluidic mixers promise unique conditions for their continuous preparation. A novel microfluidic antisolvent precipitation device was realized by two-photon-polymerization with a mixing channel in which the organic phase formed a sheet with a homogeneous thickness of down to 7 μm completely wrapped in the aqueous phase. Homogeneous diffusion through the sheet accelerates mixing. Optical access was implemented to allow in-situ dynamic light scattering. By centering the thin sheet in the microchannel cross-section, two important requirements are met. On the one hand, the organic phase never reaches the channel walls, avoiding fouling and unstable flow conditions. On the other hand, in the sheet positioned at the maximum of the parabolic flow profile the nanoparticle velocities are homogenized which enables flow-compensated Dynamic Light Scattering (flowDLS). These unique features allowed in-situ particle size determination for the first time. Monitoring of lipid nanoparticle precipitation was demonstrated for different rates of solvent and antisolvent flows. This breakthrough innovation will not only enable feedback control of nanoparticle production but also will provide new insights into the dynamics of nanoparticle precipitation.

Determining the Soil Particle Shape by Use of Dynamic Image Analysis

In Soil Science, it is well established that the geometry of individual soil particles, including their shape and size, has a significant impact on a number of key physical properties of the soil and on the processes involved with it. The shape and size of soil particles directly impact aspects such as permeability, water retention, stability of soil aggregates and the availability of nutrients for plants. Therefore, accurate determination of these characteristics of soil particles becomes extremely important for understanding and effective soil management. Nowadays, dynamic image analysis (DIA) is emerging as an exceptionally versatile and effective technique that enables precise determination of particle characteristics, including shape and size, in a dynamic and non-invasive manner. DIA enables the automatic analysis of thousands of microscopic images, allowing rapid and accurate study of the morphology of soil particles at micro and macro scales. The use of dynamic image analysis in soil research provides insight into the complex structures of soil particles and better prediction of their impact on various soil processes. Moreover, DIA enables the examination of a large number of samples in a short time, which contributes to the efficiency and precision of soil testing. Therefore, dynamic image analysis is becoming a widely used technique for determining particles' characteristics, such as shape and size. In the context of an ever-increasing awareness of the sustainable use of natural resources and the need to optimize agricultural and engineering practices, dynamic image analysis is becoming an indispensable tool for soil scientists, environmental scientists and engineers. Its versatile use can contribute to further expanding our knowledge about soil and developing innovative solutions for sustainable soil and environmental management.

Efficacy of Acacia Gum Biopolymer in Strength Improvement of Silty and Clay Soils under Varying Curing Conditions

Acacia gum (AG), a polysaccharide biopolymer, has been adopted to improve the strength of three cohesive soils by subjecting them to diverse environmental aging conditions. Being a polysaccharide and a potentially sustainable construction material, the AG yielded flexible film-like threads after 48 h upon hydration, and its pH value of 4.9 varied marginally with the aging of the stabilized soils. The soil samples for the geotechnical evaluation were subjected to wet mixing and were tested under their Optimum Moisture Content (OMC), as determined by the light compaction method. The addition of AG modified the consistency indices of the soils due to the presence of hydroxyl groups in AG, which also led to a rise in OMC and reduction in Maximum Dry Unit weight (MDU). The Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) were determined under thermal curing at 333 K as well as on the same day of sample preparation. The least performing condition of the soil’s CBR was evaluated under submerged conditions after allowing the AG-stabilized specimens to air-cure for a period of 1 week. The UCS specimens tested after 7 days were subjected to the initial 7 days of thermal curing at 333 K. A dosage of 1.5% of AG yielded the UCS of 2530 kN/m2 and CBR of 98.3%, respectively, for the low compressible clay (LCC) after subjecting the sample to 333 K temperature for 1 week. The viscosity of the AG was found to be 214.7 cP at 2% dosage. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and average particle size determination revealed the filling of pores by AG gel solution, adsorption, and hydrogen bonding, which led to improvements in macroproperties.

Determination of particle number concentration for biological particles using AF4-MALS: Dependencies on light scattering model and refractive index

Determining accurate counts and size distributions for biological particles (bioparticles) is crucial in wide-ranging fields, but current methods to this end are susceptible to bias from polydispersity in size. This bias can be mitigated by incorporating a separation step prior to characterization. For this reason, asymmetrical flow field-flow fractionation (AF4) with on-line multiangle light scattering (MALS) has become an important platform for determining particle size. AF4-MALS has also been increasingly used to report particle concentration, particularly for complex biological particles, yet the impact of light scattering models and particle refractive indices (RI) have not been quantitatively evaluated. Here, we develop an analysis workflow using AF4-MALS to simultaneously separate and determine particles sizes and concentrations. The impacts of the MALS particle counting model used to process data and the chosen RI value(s) on particle counts are systematically assessed for polystyrene latex (PSL) particles and bacterial outer membrane vesicles (OMVs) in the 20-500 nm size range. Across spherical models, PSL and OMV particle counts varied up to 13% or 200%, respectively. For the coated-sphere model used in the analysis of OMV samples, the sphere RI value greatly impacts particle counts. As the sphere RI value approaches the RI of the suspending medium, the model becomes increasingly sensitive to the light scattering signal-to-noise ratio ultimately causing erroneous particle counts. Overall, this work establishes the importance of selecting appropriate MALS models and RI values for bioparticles to obtain accurate counts and provides an AF4-MALS method to separate, enumerate, and size polydisperse bioparticles.

Beyond Creams and Gels: The Emergence of Emulgels in Pharmaceutical Science

Background: Emulgels combine the properties of emulsions and gels, offering a unique drug delivery system that enhances the solubility and stability of hydrophobic drugs. This study reviews recent advancements in emulgels and their potential in pharmaceutical applications. Objective: To systematically review the current state of research on emulgels, focusing on formulation techniques, characterization methods, and therapeutic applications. Methods: A comprehensive literature search was conducted using databases such as PubMed, Scopus, and Web of Science, covering studies published from 2010 to 2023. Inclusion criteria included articles discussing formulation techniques, characterization, and therapeutic applications of emulgels. Data extraction and quality assessment were performed independently by two reviewers. Results: Various formulation techniques, such as high-energy emulsification, phase inversion, and solvent evaporation, have been explored to enhance the bioavailability of hydrophobic drugs. Recent advancements introduced novel methods like microfluidization and ultrasound-assisted emulsification to improve formulation efficiency. Characterization techniques, including rheological analysis, particle size determination, and drug release studies, are crucial for optimizing emulgel formulations. Several patents have been filed, reflecting innovative approaches in emulgel technology, such as incorporating nanomaterials and targeted delivery systems. Therapeutic applications of emulgels have been extensively studied in dermatology, pain management, and antimicrobial therapy, showing promising results in enhancing drug efficacy and patient compliance. Conclusion: Emulgels present a versatile and efficient drug delivery system with significant potential in various therapeutic areas. Future research should focus on the large-scale production of emulgels and their long-term stability to facilitate their transition from research to clinical practice.

A machine learning-driven modeling and optimization approach for enhancing cassava mash production quality in cassava graters

Machine performance modeling and optimization have emerged as crucial steps for process enhancement and efficiency. This study explored machine learning to model and optimize the cassava grating chamber of cassava grater for the quality production of gari. This domain remains unexplored thus far. A total of 196 graters were studied. Key variables studied included tooth diameter (TD), tooth height (TH), inter-tooth spacing (ITS), drum speed (DS), clearance (C), and moisture content of cassava (MC). Geometric mean diameter (GMD) represented mash quality. Feature importance rankings emphasized TH (0.488784), C (0.243284), TD (0.112682), ITS (0.103547), DS (0.036261), and MC (0.015442) in determining particle size (GMD) of grated mash. Machine learning models efficiently interpreted these attributes, including gradient boost regressor, linear regression, neural network, and random forest. The Gradient boost regressor was the best predictive model achieving 95.34 % accuracy, RMSE (0.3291), and MAE (0.2303). The study provides a GMD predictive equation and optimized parameters for specific gari sizes production, offering valuable insights for tailored machinery in the cassava grating activity.

Absorption of commercial and nanoparticulate ZnO and MgO synthesized by combustion reaction applied to maize soil

Nanotechnology has rapidly expanded across various fields, yet its application in agriculture remains underexplored. This study investigates the impact of zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles on maize cultivation, comparing commercial samples with those synthesized by combustion reaction. Synthesized ZnO and ZnO/MgO (1:1 by mass) were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) to determine particle size and morphology. The experimental design assessed the effects of different treatments on magnesium and zinc uptake in maize roots and leaves, using atomic absorption spectrometry (AAS) for analysis. Results indicate that commercial ZnO significantly increased Zn absorption compared to synthesized samples and the control group, highlighting the influence of particle size and surface area on nutrient uptake. This study provides valuable insights into the potential of nanomaterials into the plant’s absorption mechanism as well as show that the availability of Zn NP synthesized contributes to the absorption of zinc by the plant without competing with Mg. On the other hand, when in Zn commercial, Mg absorption may be impaired.

Impacts of oyster farms on sediment-associated mercury and methylmercury concentrations and health risks in an estuarine, mangrove forest, Zhanjiang Bay, China

Estuarine sediments serve as significant reservoirs for mercury (Hg) and methylmercury(MeHg), which can also interconvert in the external environment. The release of Hg in response to human activities raises concerns about its potential ecological and human health effects. Sediment samples were collected in December 2021 from four locations (sites), and Hg cycling by measuring the concentrations of, and controls on, the spatial distribution of total Hg (THg) and methylmercury (MeHg) in high-tidal zone (HTZ) and mid-tidal zone (MTZ) sediments of a mangrove forest (MF) and oyster farm (OF) was examined in northwestern Zhanjiang Bay, including simultaneous determination of sediment particle size, oxidation-reduction potential (Eh), pH, total organic carbon (TOC), sulfide concentration (S2-), and sulfate reducing bacteria (SRB). The research results indicated that concentrations of both THg and MeHg ranged between 20.0–104.0 ng/g and 0.011–0.277 ng/g in the sediments, respectively. The highest methylation potentials within the MF and OF were in sediments located approximately 10–15 cm below the surface. MeHg in the HTZ of the OF was likely derived from exogenous inputs as Hg methylation appears limited, and the formation of MeHg depended not only on the amount of inorganic mercury available for methylation in SRB, but also on the TOC, pH, Eh and S2- content in the sediment. A risk assessment of MeHg during the anthropogenic disturbance of this estuaries conducted on individuals eating oysters demonstrated that health risks are low.

Pharmaceutical Applications and Advances with Zetasizer: An Essential Analytical Tool for Size and Zeta Potential Analysis

: Zetasizer is an advanced device that measures various properties of particles or molecules suspended in a liquid medium. It is extensively used for evaluating the size of nanoparticles, colloids, and biomolecular particles, and for determining particle charge. There are several analytical techniques by which the size, zeta potential, and molecular weight can be determined, like Dynamic Light Scattering (DLS) that measures the size of particles in dispersed systems, which can range from sub-nanometers to several micrometers in diameter. Electrophoretic Light Scattering (ELS) analyzes the mobility and charge of particles, also known as the zeta potential. Static Light Scattering (SLS) determines the molecular weight of particles in a solution. The Zetasizer is part of the Zetasizer Advance range of benchtop systems available for laboratory use. The Zetasizer Ultra model offers unique measurement capabilities, such as Multi-angle Dynamic Light Scattering (MADLS) and particle concentration. These features offer a deeper understanding of samples, making the Zetasizer a vital instrument in numerous scientific and industrial applications. In this review, we have discussed Zetasizer’s principles for the determination of particle size, zeta potential, and molecular weight, along with its qualification and applications in different formulations.

Automated system for determining particle size by moisture weight loss

An alternative method to determine the average particle size of suspensions, from the loss of moisture as function of the time is presented. Consequently, the novelty of the method consists of determining the particle size through weight loss. According to this definition, these bulk variations are collected, by controlling at the same time, parameters as the relative dampness of the chambers and the temperature of the samples under analysis. Additionally, the data are processed in the time domain and Fourier-analyzed to obtain the average particle size. Statistically, the method was calibrated through the comparison with samples previously characterized by transmission electron microscopy, by using polymer latex dispersed in water with an average particle size of 24, 44, 74 and 105 µm.

SPHERICAL AGGLOMERATION OF TELMISARTAN - AN APPROACH TO IMPROVE PHYSICOCHEMICAL PROPERTIES

The study explains the preparation of spherical agglomerates (SA) of telmisartan (TLS), a BCS class II drug used to improve it’s physicochemical and bulk properties. Drugs of this class could potentially exhibit dissolution rate limited absorption. TLS spherical agglomerates were designed using hydrophilic polymer (PVP K-30), dimethyl formamide (DMF), water and ethyl acetate (bridging liquid) by solvent change method and evaluated for micromeritic properties. The SA were characterized by particle size determination, FTIR, PXRD and SEM. The results of micromeritic studies indicated that SA showed improved flow properties due to their spherical shape and bigger size. Absence of strong interaction at molecular level and alteration in the crystal structure of TLS with modification in crystallinity was confirmed by FTIR and PXRD respectively. TLS solubility characteristics were improved by this approach.

Innovative Formulation and Evaluation of Phytosomal Nanoparticles from Ixora Coccinea Linn and its Pharmacological Screening

The use of herbal extracts in pharmaceutical formulations has gained significant attention due to their therapeutic potential and minimum side effects and shows pharmacological profiles as anti-inflammatory, anticancer, and antimicrobial. Thus, the intent of the current study was to develop a potential drug carrier system phytosomal nanoparticle using an extract of the plant “Ixora coccinea”. The extract of Ixora coccinea was prepared by using the maceration method and it is incorporated into Phytosome nanoparticles by using the solvent evaporation method. The impact of various process parameters and material attributes on the average particle size and drug entrapment efficacy. Extract loaded Phytosomal nanoparticles were characterized by particle size determination, Zeta potential, FTIR, and UV spectroscopy. The pharmacological screening consolidated antimicrobial activity was carried out by the well diffusion method, wherein it was performed against Gram Positive (B. Cerus, NCIM-2703) and Gram Negative (E. coli, NCIM 2832) bacteria strains. Which resulted in showing phytosomal nanoparticles show good activity than the extract. The anti-inflammatory activity was carried out by the protein denaturation method, which concluded that Ixora Coccinea phytosomal nanoparticles show better activity. Therefore, it results in moderate anti-inflammatory activity as compared to standard Diclofenac sodium. Keywords: Phytosome nanoparticles, Solvent evaporation method, Invitro anti-inflammatory activity.

Predicting Adhesion Energies of Metal Nanoparticles to Support Surfaces, Which Determines Metal Chemical Potential versus Particle Size and Thus Catalyst Performance

Predicting Adhesion Energies of Metal Nanoparticles to Support Surfaces, Which Determines Metal Chemical Potential versus Particle Size and Thus Catalyst Performance

(Digital Presentation) Investigation of the Damage of Focus Ion Beam (FIB) on Nanocrystals Formed in Terbium-Doped Silicon Oxide Thin Films

Terbium-doped oxygen-rich silicon oxide (ORSO:Tb) thin films were fabricated using Integrated magnetron sputtering and electron cyclotron plasma-enhanced chemical vapor deposition (IMS ECR-PECVD) method. To investigate damage from focus ion beam (a comparison is made between mechanical and FIB methods measurements, which did not reveal crystal damage induced by FIB.Silicon-based thin films are fundamental materials in electronics and photonics, and doping is a common method to enhance silicon-based thin film’s luminescence. Terbium (Tb), characterized by well-defined emission lines, ranging from 400 to 620 nm (green emission), provides compelling reasons for using Tb as a dopant in silicon-based thin films (1).TEM is a method employed for studying. Preparation methods are required to make a TEM sample that is transparent to the electron beam (with a thickness of approximately 100 to 200 nm) (2). While conventional techniques, like electrolytic polishing and mechanical milling, are commonly used for preparing TEM samples, they fall short of achieving the precise preparation of a TEM sample in a specific area of interest with high spatial resolution.FIB has been used for preparing TEM specimens, which is fast and reliable. By scanning the beam across the cross-section, it becomes possible to reduce the thickness of the sample to prepare it for TEM (4)(5). The primary issue is due to the impact of ion beams accelerated to high energy therefore, examination effect of FIB on structure is important. Damages resulting from using FIB have mainly been studied on Silicon-based materials (6)(7)(8).In this paper, Tb-doped silicon oxide (oxygen-rich) thin film deposited by IMS ECR-PECVD offers a more uniform distribution and well-controlled rare-earth doping (9). To investigate the damages induced in the preparation process, ORSO:Tb annealed at 1200 °C was divided into two parts, and then a comparison between the mechanical and FIB preparations for TEM samples was made.ORSO:Tb were fabricated using an IMS ECR-PECVD system, employing 2 sccm SiH4 at 30% Ar and 28 sccm O2 at 10% as silicon (Si) and oxygen (O) precursors. These gas sources were delivered to the ECR chamber, pure Tb target with a sputtering power of 30 W and the substrate temperature was set at 350 °C. Following deposition, the thin film underwent annealing at 1200 °C for 1 hour.The TEM samples prepared by mechanical method and annealed at 1200 ⁰C, Fig. 1(a), showed a well-defined crystal structure. The dark points on the sample represent the nanocrystals of terbium disilicate. The average thickness of the sample is approximately 168.88 nm. Fig. 1(b) displays the ORSO:Tb annealed at 1200 ⁰C, showing the cross-sectional morphology of well-ordered nanostructures on the specimen with Tb doping, prepared by FIB. The cross-section of the thin film is well-ordered, and the FIB process did not disrupt the crystal structure of the sample annealed at high temperature, nor did it lead to the formation of a new structure. Furthermore, a comparative analysis between the TEM-prepared sample employing the mechanical method and the one prepared using FIB makes it evident that the FIB-prepared sample possesses superior resolution. The size distribution of particles is approximately the same, while due to the higher resolution of the TEM sample prepared through FIB, exhibits a particle distribution with a greater range with more details. In contrast, particle size determination in the mechanical method is more challenging due to its lower resolution, determining details and size characterization more difficult. Conclusion The ORSO:Tb sample was fabricated using the IMS ECR-PECVD system at 1200 degrees. Based on the findings presented in the paper, the effect of FIB, particularly at high annealing temperatures, does not induce significant damage to the crystal structure of ORSO:Tb thin film. The particle size distribution in the TEM sample prepared with FIB is broader and more detailed than in the mechanical due to its higher resolution. Particle size determination using the mechanical method is more challenging due to its lower resolution, making it more difficult to distinguish details and characterize sizes. Additionally, atomic composition analysis indicated the accurate abundance of oxygen in oxygen-rich silicon oxide. Figure 1

Developing Online ICP-MS Methodology for Examining Catalyst Degradation Dynamics during Electrochemical CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) provides a path towards sustainable production of carbon-based fuels and chemicals, using renewable electricity to drive the conversion of CO2 into products such as ethylene, ethanol, and methane. A challenge limiting the implementation of CO2RR is catalyst stability during operation, and greater fundamental understanding is needed to uncover the governing physical, chemical, and electrochemical factors, as well as degradation mechanisms, operative under reducing conditions. One tool that can be used for conducting such fundamental studies is online inductively coupled plasma mass spectrometry (ICP-MS). In this study, an experimental framework was developed for using online ICP-MS for time-resolved degradation studies during CO2RR conditions. Using a customized flow cell setup, we coupled an ICP-MS to a potentiostat to simultaneously apply a potential or current while evaluating dynamics and degradation for both Au and Cu catalysts. Both ionic dissolution and degradation in the form of nanoparticle detachment can be detected and analyzed. The presence of nanoparticles is indicated by spikes in ICP-MS data. The intensity of the spikes is directly related to particle size. We used ICP-MS to determine particle mass, size distribution, and cumulative mass loss over time. We found the use of ICP-MS to obtain particle size distribution gave comparable results to transmission electron microscopy (TEM) determination of particle size distribution.Au foil as the CO2 reduction catalyst was used as a model system for detecting and quantifying degradation in situ using ICP-MS. We found Au degradation to occur in the form of nanoparticle detachment, with increasingly negative applied potential (0 V vs RHE to -1 V vs. RHE) in the presence of CO2 leading to increased number of nanoparticles in the electrolyte; however, no ionic dissolution was observed. In comparison, when the electrolyte was saturated with N2, nanoparticles detached from the electrode at a lower rate than in CO2-saturated conditions. We also examined Cu degradation under the same conditions as the Au system. Cu degradation occurs as both ionic dissolution and nanoparticle detachment, but under all conditions, Cu has less nanoparticle detachment and cumulative mass loss due to nanoparticles than Au. The developed experimental framework in this study would be translatable to a variety of electrocatalytic reactions and environments. Examination of catalyst degradation behavior in situ, including non-traditional degradation mechanisms such as nanoparticle detachment from bulk materials, can be used to obtain greater fundamental understanding of degradation mechanisms and rational design of materials with improved stability.

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.