Technique For Characterization Of Particles Research Articles

Image processing and neural network technique for size characterization of gravel particles

Particle size is considered one of the significant characteristics used in geotechnical practices. Traditionally, sieve analysis is utilized for coarse-grained soil. However, this method could be time consuming and take much effort, especially for large scale infrastructure projects. This paper presents an efficient method for estimating gravel particle characterization utilizing image processing and artificial neural network technique (IPNN). The proposed algorithm is performed by utilizing particle boundary delineation and shape feature extraction to train a neural network model for estimating gravel size distribution curve. It is found that excellent agreement exists between the results obtained from conventional sieve analysis and neural analysis for gravel soil particles with maximum difference in passing percentages up to only 3.70%. The proposed technique shows satisfactory results for crushed stone samples with maximum difference in passing percentages about 10.90% mainly in large diameter particles. The presented technique (IPNN) could offer a promising alternative technique for material quality control process especially in large scale projects.

Spray combustion characteristics of boron slurry fuel in high particle loading conditions

Enhancing the energy density of hydrocarbon fuels is indeed crucial, especially in the context of addressing energy needs. Incorporating energetic particles as additives into conventional liquid fuels garners increased attention due to its potential to enhance energy density. Due to its high energy potential, boron is the most promising additive in several energetic particles. However, the study focusing on the boron-loaded slurry fuels are limited. Therefore, the present work focuses on the effect of boron loading on the spray combustion of boron-loaded slurry fuel, especially at higher loadings (10%, 20% & 30% boron + Jet A-1 fuel) using a swirl-stabilized spray combustor. The research scrutinizes the feed and exhaust particles' surface morphology, chemical composition and active boron content through diverse particle characterization techniques. Furthermore, the study investigates the influence of boron loading on the combustion characteristics of slurry fuel using methods such as colour flame imaging, spectroscopy, and BO2* Chemiluminescence imaging. The impact of boron loading on the positive thermal contribution of the slurry was examined by analyzing temperature measurements at various locations within the combustor. The BO2* chemiluminescence imaging and spectroscopy results indicate that the intensity of BO2 emission increases with a rise in particle loading. The temperature results reveal an increase in temperature compared to pure Jet A-1 for all the boron-loaded cases. In particular, JB10 and JB20 achieved nearly 90% and 85% of the theoretical temperature increase. The diffractogram and thermogravimetric results of the burnt particles collected show that the particles were burnt thoroughly for the boron-loaded cases.

Challenges in the analysis of pharmaceutical lentiviral vector products by orthogonal and complementary physical (nano)particle characterization techniques

Lentiviral vectors (LVVs) are used as a starting material to generate chimeric antigen receptor (CAR) T cells. Therefore, LVVs need to be carefully analyzed to ensure safety, quality, and potency of the final product. We evaluated orthogonal and complementary analytical techniques for their suitability to characterize particulate matter (impurities and LVVs) in pharmaceutical LVV materials at development stage derived from suspension and adherent manufacturing processes. Microfluidic resistive pulse sensing (MRPS) with additional manual data fitting enabled the assessment of mode diameters for particles in the expected LVV size range in material from adherent production. LVV material from a suspension process, however, contained substantial amounts of particulate impurities which blocked MRPS cartridges. Sedimentation-velocity analytical ultracentrifugation (SV-AUC) resolved the LVV peak in material from adherent production well, whereas in more polydisperse samples from suspension production, presence of particulate impurities masked a potential signal assignable to LVVs. In interferometric light microscopy (ILM) and nanoparticle tracking analysis (NTA), lower size detection limits close to ∼ 70 nm resulted in an apparent peak in particle size distributions at the expected size for LVVs emphasizing the need to interpret these data with care. Interpretation of data from dynamic light scattering (DLS) was limited by insufficient size resolution and sample polydispersity. In conclusion, the analysis of LVV products manufactured at pharmaceutical scale with current state-of-the-art physical (nano)particle characterization techniques was challenging due to the presence of particulate impurities of heterogeneous size. Among the evaluated techniques, MRPS and SV-AUC were most promising yielding acceptable results at least for material from adherent production.

Effect of alkali metal salt addition on disintegration of titania particles precipitated from tetraethyl orthotitanate in ethanol

AbstractInline (or in situ) photon density wave spectroscopy was used to monitor the disintegration of secondary titania particles into their primary particles. Photon density wave spectroscopy can be applied to determine the reduced scattering coefficient of a dispersion without dilution or calibration, and thus enables process analysis in materials that are usually unsuitable for established particle characterization techniques. In this work, amorphous titania particles were precipitated from tetraethyl orthotitanate in ethanol by addition of water in presence of different alkali metal salts (NaCl, KCl, CsCl, K2SO4) with concentrations between 0 and 1.6 mM. The present results suggest that the synthesized titania secondary particles disintegrate into their primary particles if the electrostatic repulsion between the primary particles is promoted. This can be achieved by an increased alkali chloride concentration in the synthesis or by addition of larger alkali metal ions. In contrast, the particles are only weakly charged upon addition of sulfate ions, and the disintegration stops. The conclusions drawn from photon density wave spectroscopy results are supported by gravimetric determination of the particle yield, dynamic light scattering measurements, zeta‐potential measurements, and electron micrographs. Additionally, the disintegration was driven to completion by addition of hydrochloric acid to create a transparent suspension of titania primary particles as small as 4.7 nm.

Three-Dimensional Homodyne Light Detection (3D-HLD) for High-Throughput Submicron Particle Analysis in (Highly Concentrated) Protein Biopharmaceuticals, Viral Vectors, and LNPs

During biopharmaceutical development, particle monitoring and characterization are crucial. Notably, particles can be impurities considered as critical quality attribute, or active pharmaceutical ingredient (e.g., viral vectors) or drug delivery system (e.g., lipid nanoparticles) itself. Three-dimensional homodyne light detection (3D-HLD) is a novel technique that can characterize particles in the ∼0.2 µm to 2.0 µm size range.We evaluated 3D-HLD for the analysis of high concentration protein formulations (up to 200 mg/mL), where formulation refractive index and background noise became limiting factors with increasing protein concentration. Sample viscosity however did not impact 3D-HLD results, in contrast to comparative analyses with NTA and MRPS. We also applied 3D-HLD in high-throughput screenings at high protein concentration or of lipid nanoparticle and viral vector formulations, where impurities were analyzed in the presence of a small (<0.2 µm) particulate active pharmaceutical ingredient. 3D-HLD turned out to be in good agreement with or a good complement to other state-of-the-art particle characterization techniques, including BMI, MRPS, and DLS.The main application of 3D-HLD is high-throughput particle analysis at low sample volume. Follow-up investigation of the optimized particle sizing approach and of detection settings could further improve the understanding of the method and potentially increase ease of operation.

Efficient quenching sheds light on early stages of gold nanoparticle formation.

The formation mechanism of plasmonic gold nanoparticles (Au NPs) by fast NaBH4 induced reduction of the precursors is still under debate. In this work we introduce a simple method to access intermediate species of Au NPs by quenching the solid formation process at desired time periods. In this way, we take advantage of the covalent binding of glutathione on Au NPs to stop their growth. By applying a plethora of precise particle characterization techniques, we shed new light on the early stages of particle formation. The results of in situ UV/vis measurements, ex situ sedimentation coefficient analysis by analytical ultracentrifugation, size exclusion high performance liquid chromatography, electrospray ionization mass spectrometry supported by mobility classification and scanning transmission electron microscopy suggest an initial rapid formation of small non-plasmonic Au clusters with Au10 as the main species followed by their growth to plasmonic Au NPs by agglomeration. The fast reduction of gold salts by NaBH4 depends on mixing which is hard to control during the scale-up of batch processes. Thus, we transferred the Au NP synthesis to a continuous flow process with improved mixing. We observed that the mean volume particle sizes and the width of the particle size distribution decrease with increasing flow rate and thus higher energy input. Mixing- and reaction-controlled regimes are identified.

Particle Property Characterization and Data Curation for Effective Powder Property Modeling in the Pharmaceutical Industry.

Computational modeling, machine learning, and statistical data analysis are increasingly utilized to mitigate chemistry, manufacturing, and control failures related to particle properties in solid dosage form manufacture. Advances in particle characterization techniques and computational approaches provide unprecedented opportunities to explore relationships between particle morphology and drug product manufacturability. Achieving this, however, has numerous challenges such as producing and appropriately curating robust particle size and shape data. Addressing these challenges requires a harmonized strategy from material sampling practices, characterization technique selection, and data curation to provide data sets which are informative on material properties. Herein, common sources of error in particle characterization and data compression are reviewed, and a proposal for providing robust particle morphology (size and shape) data to support modeling efforts, approaches for data curation, and the outlook for modeling particle properties are discussed.

Evaluation of the Effect of Multiparticle on Lithium-Ion Battery Performance Using an Electrochemical Model

Dear Editor, This letter focuses on modeling the electrode heterogeneity by extending the pseudo-two-dimensional model (P2D) with actual particle-size distributions (PSD). The effects of different particle characterization techniques, including the area-weighted, volume-weighted, and number-based methods on cell dynamics are compared. The model with number-based PSD achieves better rate capability (maximum 2.0% improvement in capacity, maximum 2.6% increase in energy). Besides, the effectiveness of the multiparticle (MP) model is evaluated against the single-particle model (SPME) and P2D model under fast charging conditions. Results show that the PSD generates greater heterogeneities of cell internal states at higher C-rates current.

Synthesis of High Molecular Weight Water-Soluble Polymers as Low-Viscosity Latex Particles by RAFT Aqueous Dispersion Polymerization in Highly Salty Media.

We report the synthesis of sterically-stabilized diblock copolymer particles at 20% w/w solids via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of N,N′-dimethylacrylamide (DMAC) in highly salty media (2.0 M (NH4)2SO4). This is achieved by selecting a well-known zwitterionic water-soluble polymer, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), to act as the salt-tolerant soluble precursor block. A relatively high degree of polymerization (DP) can be targeted for the salt-insoluble PDMAC block, which leads to the formation of a turbid free-flowing dispersion of PDMAC-core particles by a steric stabilization mechanism. 1H NMR spectroscopy studies indicate that relatively high DMAC conversions (>99%) can be achieved within a few hours at 30 °C. Aqueous GPC analysis indicates high blocking efficiencies and unimodal molecular weight distributions, although dispersities increase monotonically as higher degrees of polymerization (DPs) are targeted for the PDMAC block. Particle characterization techniques include dynamic light scattering (DLS) and electrophoretic light scattering (ELS) using a state-of-the-art instrument that enables accurate ζ potential measurements in a concentrated salt solution. 1H NMR spectroscopy studies confirm that dilution of the as-synthesized dispersions using deionized water lowers the background salt concentration and hence causes in situ molecular dissolution of the salt-intolerant PDMAC chains, which leads to a substantial thickening effect and the formation of transparent gels. Thus, this new polymerization-induced self-assembly (PISA) formulation enables high molecular weight water-soluble polymers to be prepared in a highly convenient, low-viscosity form. In principle, such aqueous PISA formulations are highly attractive: there are various commercial applications for high molecular weight water-soluble polymers, while the well-known negative aspects of using a RAFT agent (i.e., its cost, color, and malodor) are minimized when targeting such high DPs.

Development of a high-throughput RT-PCR based viral infectivity assay for monitoring the stability of a replicating recombinant Lymphocytic Choriomeningitis viral vector

Traditional virus infectivity titration methods for lymphocytic choriomeningitis virus (LCMV) are laborious, time-consuming, and low-throughput (e.g., focus forming unit (FFA) assay). In this report, we developed a high-throughput reverse transcription quantitative PCR (RT-qPCR)-based virus infectivity assay for relative quantitation of a live, recombinant replicating LCMV -based viral vector (TT1). This in vitro infectivity assay demonstrated a 4-log linear range for TT1 titer quantitation. A high positive Pearson correlation coefficient value (≥ 0.80) was obtained between the RT-qPCR vs. the “gold-standard” FFU assay when comparing the stability profiles of stressed TT1 vector samples. In addition to the RT-qPCR infectivity assay, the stability of the TT1 vector upon freeze-thaw stress was investigated further with complementary viral particle characterization techniques (e.g., TEM, NTA, MFI). Correlations between viral infectivity and particle measurements during forced degradation studies were observed to be specific to the TT1 vector and its various formulations and such results facilitated the rank-ordering of formulation conditions. Overall, this infectivity RT-qPCR method showed increased sample throughput and improved assay flexibility compared to traditional viral infectivity assays. These results are discussed in the context of enabling future TT1 vector formulation development work, and potential utilization as an in-process monitoring tool during TT1 vector manufacturing.

A high-resolution study of in situ surface-enhanced Raman scattering nanotag behavior in biological systems

The colloidal stability of surface-enhanced Raman scattering (SERS) nanotags (Raman reporter-conjugated plasmonic nanoparticles) significantly affects the accuracy and reproducibility of SERS measurements, particularly in biological systems. Limited understanding of SERS nanotag stability may partly hamper the translation of SERS nanotags from the laboratory to their use in the clinic. In this contribution, we utilized differential centrifugal sedimentation (DCS), a reliable and straightforward technique to comprehensively analyze the colloidal stability of SERS nanotags in biological systems. Compared with other particle characterization techniques, DCS has been shown to have a unique advantage for high-resolution and high-throughput polydisperse particle characterization. DCS data revealed that the universal aggregation prevention practice of coating SERS nanotags with silica or bovine serum albumin layers did not sufficiently stabilize them in common measurement environments (e.g., 1 × PBS). Combined DCS and SERS measurements established a strong correlation between the degrees of nanotag aggregation and signal intensities, further reinforcing the necessity of characterizing SERS nanotag stability for every condition in which they are used. We also found that increasing the protein thickness by the inclusion of extra protein components in the detection environments and antibody functionalization can improve the stability of SERS nanotags. We believe that this study can provide guidelines on appropriate measurement techniques and particle design considerations to assess and improve SERS nanotag stability in complex biological systems.

Depolarization of nearly spherical particles: The Debye series approach

Backscattering depolarization of nonspherical particles plays a critical role in active Light Detection And Ranging (LiDAR) retrievals of cloud or aerosol parameters, as well as in particle characterization techniques. However, the interpretation of backscattering light from particles is a challenging research subject. This paper addresses the depolarization of nearly spherical particles by using the Debye series approach. Specifically, the T matrix is represented as an infinite sum of terms; the terms in the expansion are correspondingly associated with diffraction and reflection ($p=0$), and multiple transmissions ($pg0$) from the particle to the medium as waves undergo internal reflections. We found that the enhanced depolarization for optically soft particles stems from multiple transmissions. However, this is mostly from the transmission after one internal reflection ($p=2$), when the refractive index is larger than 1.3. Moreover, the interference among multiple transmissions was found to play an essential role in suppressing the depolarization ratio as the refractive index approaches unity. These findings have implications in interpreting the backscattering optical properties of atmospheric aerosols and hydrosols in water.

Bathophenanthroline Disulfonate Ligand-Induced Self-Assembly of Ir(III) Complexes in Water: An Intriguing Class of Photoluminescent Soft Materials.

Strong evidence of concentration-induced and dissolved electrolyte-induced chromophore aggregation has been universally observed in numerous water soluble bis-cyclometalated Ir(III) photosensitizers bearing the sulfonated diimine ligands bathophenanthroline disulfonate and bathocuproine disulfonate. This new class of aqueous-based soft materials was highly photoluminescent in their aggregated state where detailed spectroscopic investigations of this phenomenon revealed significant blue shifts of their respective photoluminescence emission spectra with concomitant increases in excited-state lifetimes and quantum yields initiating even at micromolar chromophore concentrations in water or upon the addition of a strong electrolyte. A combination of nanoscale particle characterization techniques, static and dynamic photoluminescence spectroscopic studies, along with atomistic molecular dynamics (MD) simulations of these soft materials suggests the formation of small, heterogeneous nanoaggregate structures, wherein the sulfonated diimine ancillary ligand serves as a pro-aggregating subunit in all instances. Importantly, the experimental and MD findings suggest the likelihood of discovering similar aqueous aggregation phenomena occurring in all transition-metal complexes bearing these water-solubilizing diimine ligands.

Sheathless Microflow Cytometry Using Viscoelastic Fluids

Microflow cytometry is a powerful technique for characterization of particles suspended in a solution. In this work, we present a microflow cytometer based on viscoelastic focusing. 3D single-line focusing of microparticles was achieved in a straight capillary using viscoelastic focusing which alleviated the need for sheath flow or any other actuation mechanism. Optical detection was performed by fiber coupled light source and photodetectors. Using this system, we present the detection of microparticles suspended in three different viscoelastic solutions. The rheological properties of the solutions were measured and used to assess the focusing performance both analytically and numerically. The results were verified experimentally, and it has been shown that polyethlyene oxide (PEO) and hyaluronic acid (HA) based sheathless microflow cytometer demonstrates similar performance to state-of-the art flow cytometers. The sheathless microflow cytometer was shown to present 780 particles/s throughput and 5.8% CV for the forward scatter signal for HA-based focusing. The presented system is composed of a single capillary to accommodate the fluid and optical fibers to couple the light to the fluid of interest. Thanks to its simplicity, the system has the potential to widen the applicability of microflow cytometers.

Use of Debye's series to determine the optimal edge-effect terms for computing the extinction efficiencies of spheroids.

The extinction efficiencies of atmospheric particles are essential to determining radiation attenuation and thus are fundamentally related to atmospheric radiative transfer. The extinction efficiencies can also be used to retrieve particle sizes or refractive indices through particle characterization techniques. This study first uses the Debye series to improve the accuracy of high-frequency extinction formulae for spheroids in the context of Complex angular momentum theory by determining an optimal number of edge-effect terms. We show that the optimal edge-effect terms can be accurately obtained by comparing the results from the approximate formula with their counterparts computed from the invariant imbedding Debye series and T-matrix methods. An invariant imbedding T-matrix method is employed for particles with strong absorption, in which case the extinction efficiency is equivalent to two plus the edge-effect efficiency. For weakly absorptive or non-absorptive particles, the T-matrix results contain the interference between the diffraction and higher-order transmitted rays. Therefore, the Debye series was used to compute the edge-effect efficiency by separating the interference from the transmission on the extinction efficiency. We found that the optimal number strongly depends on the refractive index and is relatively insensitive to the particle geometry and size parameter. By building a table of optimal numbers of edge-effect terms, we developed an efficient and accurate extinction simulator that has been fully tested for randomly oriented spheroids with various aspect ratios and a wide range of refractive indices.

Advanced Particle Characterization Techniques

Advanced Particle Characterization Techniques

A new real-time bio-aerosol fluorescence detector based on semiconductor CW excitation UV laser

We present development and performance tests of a new single particle bio-detector (BARDet – Bio-AeRosol Detector) for real time air monitoring. The instrument uses single CW laser at 375nm and measures scattering signal intensity and fluorescence of individual particles in seven spectral bands. The device is integrated into a single compact enclosure and allows remote operation on mobile platform. The bio-aerosol detector is equipped with internal computer and SSD (Solid State Drive) for real time data acquisition and analysis. The final result is sent to the remote operator. Classification of aerosols with known fluorescence properties was performed using Principal Component Analysis (PCA). It showed that pollens are well separated from flours, riboflavin and culture media. The classification effectiveness of particular groups of substances varied from 88 to 98%. We demonstrated a new technological approach to air monitoring combining laser induced fluorescence particle characterization technique with internal computer that performs real-time data analysis and classification. In consequence the BARDet could be used as a remote sensor integrated with the robot. This introduces a new quality and improves versatility of air monitoring.

Particle Advances

While the journal Particle & Particle Systems Characterization is entering its 33rd volume, the relaunched and restructured Particle is just about to enter its 4th year of publication. This is a point that provided much confusion for our authors in the initial years after the relaunch at the start of 2013. However, in the intervening period, the journal has evolved into an increasingly attractive option in which to publish cutting-edge, particle-related research across the broad field of materials science. With no shortage of journals, both well-established and new, for authors to choose from in which to disseminate their original research results to their peers, we are grateful that they entrust their work to us. Earlier this year we highlighted a number of original articles that have been highly accessed and a number of overview, review-type articles that have caught the attention of the community. These articles are free for you to read, please follow the links provided on our news portal Materials Views http://www.materialsviews.com/best-of-particle-enjoy-free-access/. Particle belongs to the Advanced Materials journal family (see Figure 1). Selected articles from all journals in the portfolio can be accessed here http://www.emagcloud.com/wiley/AdvancedFamilyBooklet2/index.html. I often feel rather privileged as an editor, as we are among the first people that get to read exciting research discoveries before the articles make it to press and in doing so to a larger readership. However, I have to acknowledge at this stage the excellent work that our expert reviewers do, which enables a stringent evaluation process, ensuring that only the highest quality articles make it into a published issue. I am also indebted to our most active Editorial Advisory Board members who, through their involvement and enthusiastic engagement, have provided enormous support to Particle since the board was established at the start of 2013. The impact factor of a journal is a metric that is well known to our authors and readers. Without wanting to dwell on this number, or the interpretation of it, I can mention that Particle received its first partial impact factor in 2015. To clarify, the partial impact factor is calculated by counting the number of times articles published in 2012 and 2013 were cited in Thompson Reuters ISI Web of Science indexed journals in 2014. The impact factor of 3.081 shows strong growth in the first year since the relaunch, an increase of 474% on the journal prior to relaunch. It has to be acknowledged that this is in part due to the change in focus pre and post relaunch; while the prior focus was on the fields of industrial chemistry and engineering, the new focus of the journal is on materials science. However, this new impact factor also shows that the articles we have published since the start of 2013 are widely read and are of relevance to researchers working in many areas of materials science. Particle will receive its first impact factor (based on two years of post-relaunch citation) in June 2016, which will report further strong growth. In the editorial office our main focus going forward is to keep the quality of published work at a high level. In planning for 2016 are a number of topical special issues on catalytic micro- and nanoparticles, energy materials, advanced particle characterization techniques, and on nanocrystals and their emerging applications, among others. We welcome suggestions for further projects and are contactable on the address [email protected] Also, I invite you to connect with me on LinkedIn, should you use this professional network, where I regularly provide access to selected articles from the most recently published journal issues.

Characterization of the Physical Stability of a Lyophilized IgG1 mAb after Accelerated Shipping-Like Stress

Upon exposure to shaking stress, an IgG1 mAb formulation in both the liquid and lyophilized state formed subvisible particles. Because freeze-drying was expected to minimize protein physical instability under these conditions, the extent and nature of aggregate formation in the lyophilized preparation were examined using a variety of particle characterization techniques. The effects of formulation variables such as residual moisture content, reconstitution rate, and reconstitution medium were also examined. Upon reconstitution of shake-stressed lyophilized mAb, differences in protein particle size and number were observed by microflow digital imaging, with the reconstitution medium having the largest impact. Shake stress had minor effects on the structure of protein within the particles as shown by SDS-PAGE and FTIR analysis. The lyophilized mAb was shake stressed to different extents and stored for 3 months at different temperatures. Both extent of cake collapse and storage temperature affected the physical stability of the shake-stressed lyophilized mAb upon subsequent storage. These findings demonstrate that physical degradation upon shaking of a lyophilized IgG1 mAb formulation includes not only cake breakage, but also results in an increase in subvisible particles and turbidity upon reconstitution. The shake-induced cake breakage of the lyophilized IgG1 mAb formulation also resulted in decreased physical stability upon storage.

A quantitative determination of magnetic nanoparticle separation using on-off field operation of quadrupole magnetic field-flow fractionation (QMgFFF).

Quadrupole Magnetic Field-Flow Fractionation (QMgFFF) is a technique for characterization of sub-micrometer magnetic particles based on their retention in the magnetic field from flowing suspensions. Different magnetic field strengths and volumetric flow rates were tested using on-off field application and two commercial nanoparticle preparations that significantly differed in their retention parameter, λ (by nearly 8-fold). The fractograms showed a regular pattern of higher retention (98.6% v. 53.3%) for the larger particle (200 nm v. 90 nm) at the higher flow rate (0.05 mL/min v. 0.01 mL/min) at the highest magnetic field (0.52 T), as expected because of its lower retention parameter. The significance of this approach is a demonstration of a system that is simpler in operation than a programmed field QMgFFF in applications to particle mixtures consisting of two distinct particle fractions. This approach could be useful for detection of unwanted particulate contaminants, especially important in industrial and biomedical applications.