Particle Size Distribution Profiles Research Articles

Preparation of kartogenin-loaded PLGA microspheres and a study of their drug release profiles

Introduction: Kartogenin, a potent inducer of chondrogenic differentiation in mesenchymal stem cells and a key agent in cartilage regeneration, presents a viable therapeutic strategy for osteoarthritis management. Despite the abundance of literature on therapeutic potential of kartogenin, there is a paucity of studies characterizing the formulation specifics in microsphere fabrication. This exploration is pivotal to advances in regenerative medicine, particularly in the domain of cartilage regeneration, to assure clinical efficacy and safety.Methods: In this work, we fabricated kartogenin-loaded PLGA microspheres with diverse formulations and their particle size, size distribution, encapsulation efficiency, drug loading and release profiles were characterized. Ratio of polymer, drug, and solvent and the use of surfactant was used as variables, and in particular, the effect of surfactant on particles was investigated.Results: The average diameter of the spheres was 16.0–31.7 μm. Morphological variations from solid to porous surface structures depending on surfactant incorporation during the emulsification process was observed. Cumulative kartogenin release from microspheres ranged from 53.8% to 80.9% on day 28, and release profiles conform predominantly to the Korsmeyer-Peppas kinetics model.Discussion: This study provides a foundational framework for modulating kartogenin release dynamics, a critical consideration for optimizing therapeutic efficacy and minimizing adverse effects in cartilage tissue engineering applications.

Fabrication and characterization of W1/O/W2 double emulsions stabilized with Pleurotus geesteranus protein particles via one-step emulsification

In this study, Pleurotus geesteranus protein isolate (PPI) with low solubility in water was fabricated into nanoparticle (PPIP) that can be uniformly dispersed in pH 7.0 aqueous solution using pH cycle method. PPIP with a zeta potential of −19.21 mV had a mean size of 250.53 nm and two main peaks in particle size distribution profile. This was consistent with the TEM results, which existed both as individual particles and as particle aggregates. The main force responsible for maintaining the structure of protein particles was hydrogen bonding. Interestingly, these protein particles were successfully utilized to fabricate W1/O/W2 double emulsions using one-step homogenous emulsification, and the formation and properties of PPIP-stabilized W1/O/W2 double emulsions were significantly influenced by the protein particle concentration, oil content, and salt concentration in W2 continuous phase. Specifically, higher particle concentration and salt concentration caused a reduction in the number of W1/O droplets and the size of oil droplets. Conversely, an increase in oil content increased the number of W1/O droplets primarily due to the augmentation in the size of oil droplets. The gel strength of double emulsions was enhanced with particle concentration and oil content, as this led to the formation of stronger particle networks and droplet networks. While an opposite phenomenon was found in increasing salt concentration in W2 continuous phase, possibly resulting from the disruption of the ordered gel network. These findings not only provide new food-grade emulsifiers for W1/O/W2 double emulsions, but also broaden the application of edible mushroom proteins in food industry.

Reproducibility of physico-chemical properties in brakes emissions generated at the dynamometric bench

Reproducible generation, collection and physico-chemical characterization of brakes emissions are necessary when comparing particulates generated by different friction couples, brake designs or driving conditions. Furthermore, they are pivotal to provide universally reliable chemical information for source apportionment studies as well as for toxicological investigations and environmental assessments. Non-exhaust particulates generated by brakes are nowadays commonly collected at suitably designed variable inertia dynamometer benches, during selected braking test cycles in controlled conditions to avoid other contributions from the environment. In spite of being simplified models of a single real car semi-axis corner, dynamometric benches for brakes emissions collection still remain elaborate mechanical devices used for testing complex materials. Therefore, if the tribological interaction is not kept constant over different tests, significantly different local forces and temperatures might be expected at the tribological interface. This can eventually result in the generation of particulates with different granulometry and chemical composition, even if originated by the same braking device components. At this regard, the work here presented explores for the first time the capability of a brake dynamometer bench dedicated to emission tests to generate reproducible particulates. In particular, the assessment of the intrabench reproducibility over an extended period of time and number of tests is discussed. Specifically, the variability of physico-chemical properties such as particle size distribution, elemental composition and crystalline phase distribution is evaluated. In detail, it is observed that the elemental concentration of main constituents such as Iron and Oxygen are statistically equivalent during a set of ten tests, even at strict confidence level (α = 0.05). In addition, when statistical differences are observed in elemental concentration of secondary and minor constituents, their variability typically remains limited below the 10 % of the corresponding figure of merit. Similar findings are also observed when assessing the phase composition of main constituents compounds, such as Iron oxides, as well as the particle size distribution profiles. Conversely, higher relative variabilities up to 25 % are registered when assessing the phase composition of secondary and minor phases. The reported results are meant to provide a first critical assessment on the variability of both the size distribution and the chemical composition of the emissions generated by brakes in the laboratory environment typically used for their generation, measurements and collection.

The physicochemical properties and heat stability of milk fortified with blackberry juice and different casein-dominant ingredients

The influence of blackberry juice (BBJ) on the physicochemical properties and heat stability of skimmed milk with and without sodium caseinate or micellar casein concentrate (MCC) addition was investigated. This was performed by measuring the ionic calcium content, heat coagulation time, viscosity, particle size distribution and analytical centrifugation profiles of the different samples. BBJ decreased the ionic calcium of the samples, which resulted in a higher heat coagulation time at pH < 6.5. Its addition also prevented the increase in viscosity observed in skimmed milk and skimmed milk with MCC at pH 6.2 after heating. The particle size distribution, turbidity and analytical centrifugation profiles indicated this was due to a prevention of protein aggregation. In conclusion, the blackberry juice improved the heat stability of different types of milk systems in the pH range between 6.2 and 6.4, which was likely due to binding of calcium by blackberry polyphenols.

Application of the UV-C assisted persulphate/peroxymonosulphate process for the mineralization of organic substances in drinking water

The aim of this study was to evaluate the high oxidation potential of hydroxyl and sulphate radicals generated by UV-C assisted persulphate (PS) and peroxymonosulphate (PMS) processes in natural water. The effects of initial oxidant concentration on degradation processes were investigated using TOC, PS, pH, and UV254 measurements in samples taken at specific time intervals. The particle size distribution profiles were also determined for the raw water and effluent samples from the PS/UV-C and PMS/UV-C. Accordingly, the final removal rates were 19%, 40%, and 55% for PS/UV-C doses of 0.2 mM, 0.5 mM, and 1.0 mM, respectively, while the TOC removal was 20%, 35%, and 64% for 0.2 mM, 0.5 mM, and 1.0 mM PMS/UV-C, respectively. The results showed that the rate constants of TOC removal followed first-order kinetics for both PS and PMS. The general assessment of energy consumption during the PS/UV-C and PMS/UV-C processes showed that the time required for the same amount of TOC removal decreased as the initial PS/PMS concentration increased, so that the energy required decreased in relation to volume and mass. Overall, the obtained results were used for a comparative analysis of the oxidation process, and the recommended process was evaluated with samples taken from the effluent of each unit of the drinking water treatment plant to determine the correct location for the treatment process. The results showed that the PS/UV-C process should be designed after filtration, rather than after sedimentation, and the end of the treatment plant.

Spatio-temporal exposure assessment of particulate matter pollution in auto-rickshaw drivers in Chennai, India

Rapid urbanization and population growth have put a lot of stress on the urban infrastructure. The number of vehicles, particularly the three wheeled auto-rickshaws, have increased drastically in the past decade in developing countries like India, Pakistan, Bangladesh, etc. The distinct design of these vehicles make the drivers and the passengers vulnerable to the traffic emissions and resuspended dust. With the objective of assessing the exposure of auto-rickshaw drivers to particulate matter in Chennai, this study used an auto-rickshaw to monitor the particulate matter (PM10, PM2.5 and PM1) concentrations during weekday peak and non-peak hours, across 15 administrative zones of Chennai, India. The particle size distribution profile for each zone was identified to understand the source contribution. Low PM2.5/PM10 ratio (<0.15) was observed in the western parts of Chennai consisting residential and commercial zones (zone 10 and 11), and high PM1/PM2.5 ratio (>0.8) in the highly industrialized northern parts of Chennai (zone 4 and 5). The coarse particles of size 31 μm and 34 μm were predominant in most of the zones. Northern and central Chennai had 100 % exceedances in PM10 and PM2.5 during both peak and non-peak hour. Auto-rickshaw drivers were exposed to a maximum of 4.26 μg/km and 0.12 μg/km of PM2.5 and PM1, respectively. Based on these results, we suggest the auto-rickshaw drivers and passengers to follow necessary precautions like wearing masks, and the policymakers to develop control measures based on such spatial studies of air pollution across the entire city.

Investigating the Effects of Cascading Accelerated Stress Tests (ASTs) on the Localized Electrochemical Performance Degradation in Polymer Electrolyte Fuel Cells (PEFCs)

With a recent shift in focus from light-duty to heavy-duty vehicle applications, the durability and performance targets for polymer electrolyte fuel cells (PEFCs) have become even more stringent and challenging to achieve; for example, a net power output of 2.5 kW/g-PGM (1.07 A/cm2 current density) at 0.7 V is required after 25,000 hour-equivalent accelerated stress test (AST) [1]. Generally, different ASTs are designed to evaluate Pt electrocatalyst and support durability; for example, a square-wave (SW) AST with H2/N2 between 0.6 V to 0.95 V vs. reversible hydrogen electrode (RHE) targets Pt catalyst and a separate triangular-wave (TW) AST with a higher potential range (1 – 1.5 V vs. RHE) assesses the durability of carbon-based supports [2]. Recently, many studies [3]–[7] have revealed the heterogeneous nature of cathode catalyst layer degradation under different ASTs. Fuel cell electric vehicles are typically subjected to an enormous number of load/unload and start/stop cycles during regular operation. Though there is a considerable body of literature discussing the isolated effects of load/unload and start/stop cycles on durability and performance, there is a dearth of studies exploring the effects of cascading load/unload and start/stop cycles, a scenario more relevant to actual automotive conditions. In the present study, a segmented cell along with ex-situ Pt particle size mapping (through micro-X-ray diffraction) is used to understand the effects of cascading a DoE square-wave AST (0.6 V to 0.95 V vs. RHE) and a triangular-wave (1 – 1.5 V vs. RHE) on the durability and performance of a PEFC.The membrane electrode assemblies (MEAs) are subjected to two cascade ASTs. The first one involves 15k cycles of SW AST followed by 2.5k cycles of TW AST (referred to as Pt-followed-by-carbon, PtfCC, AST) and the other one involves 2.5k cycles of TW AST followed by 15k cycles of SW AST (referred to as Carbon-followed-by-Pt, CCfPt, AST). Multiple in-situ and post-mortem ex-situ techniques are used to obtain particle size distribution and spatial degradation profiles. Preliminary results indicate that the performance losses at the end-of-life (EOL) depend on the cascade order; PtfCC AST leads to higher losses compared to CCfPt AST in wet polarization conditions. The local current distributions are also strongly impacted by the cascade order during the aging process. Figure 1 shows the polarization performance of the samples at the beginning, middle (following the first AST), and the end-of-life of cascade ASTs.

Comprehensive study on particle size distribution, MAH and PAH profiles during alkylbenzene pyrolysis

The 5 linear alkylbenzenes, i.e., toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene as fuels underwent pyrolysis at temperatures from 950 to 1450 °C in a flow reactor. Measurements of particle number size distribution, 11 monocyclic aromatic hydrocarbons, and 3 groups of polycyclic aromatic hydrocarbons (20 unsubstituted PAHs, 5 aliphatic-bridged PAHs, and 10 methyl PAHs) during the pyrolysis of linear alkylbenzenes were conducted. Results showed that the increase in side chain length suppressed the formation of particles, but ethylbenzene produced the highest particle mass and most extensive particle number size distribution. Total particle peak number concentrations exhibited a rise-then-fall trend (peaking at a critical temperature of 1050 °C) with increasing temperature regardless of the side chain length, indicating that high temperature promoted a transition from nucleation to agglomeration and coagulation. Total PAH mass concentrations were ranked in the same order with the variation of side-chain length as particle mass and peak number concentrations, indicating that soot nucleation was highly related to total PAH mass concentrations. Unsubstituted PAHs accounted for most PAHs while substituted·PAHs, including aliphatic-bridged PAHs and methyl PAHs presented 1–2 orders of magnitude less than the corresponding unsubstituted PAHs, probably distinct thermal stability and reactivity led to different growth routes between unsubstituted and substituted PAHs. Increasing the temperature from 950 to 1250 °C, the formation of high molecular weight PAHs was promoted. while a drop of high molecular weight fractions was observed above 1350 °C, which is attributed to the suppression of the formation, as well as their conversions of high molecular weight PAHs to heavier unidentified PAHs or soot. Among the test alkylbenzene fuels, the fuels with a long side chain benefit from the reduction of particles and PAHs. Furthermore, carbon atoms in aromatic rings are dominant sources of large PAHs and particles, while the carbon atoms in aliphatic side chains mainly form gas species.

Spatial and PMF analysis of particle size distributions simultaneously measured at four locations at the roadside of highways

In urban areas, particulate matter emitted from vehicles directly affects the health of citizens near roads. Thus, in this study, particle size distribution was measured by the horizontal and vertical distances along a highway road with heavy traffic to characterize the dispersion phenomena of particulate matter emitted from vehicles. In addition, the contribution of pollution sources was analyzed using a source-receptor model. A concentration gradient was observed in which the concentration decreased with the increase in the distance from the road when the wind blew from the road to the monitoring locations. The concentration was slightly higher within 50 m of the road when the wind blows parallel to the road, and similar concentrations were found at the other monitoring locations further away from the roads. In particular, the higher the turbulence intensity of the wind, the lower is the concentration gradient coefficient because of the more enhanced mixing and dispersion. A positive matrix factorization (PMF) model with the measured particle size distribution data in the range of 9–300 nm resulted in a contribution of about 70 % (number) and 20 % (mass) to particle concentrations because of six types of vehicles including LPG, two gasoline vehicles (GDI, MPI), and three diesel vehicles with 3rd, 4th, and 5th emission classes. It showed a decrease in the vehicular contribution as the distance from the road increased. Particle number concentrations decreased with increasing altitude up to 30 m above the ground. The results of this study can be useful in deriving generalized gradient equations of particle concentrations exposed by distance and wind direction at the roadside using traffic and meteorological conditions and for establishing environmental policies, such as roadside exposure assessment, in the future. A capsule abstractDispersion of particles emitted from vehicles on a busy highway was characterized by roadside measurements of horizontal and vertical profiles of particle size distributions measured at four locations. The source profiles and contributions were estimated by major sources using a source-receptor model such as PMF.

Probing the influence of liquid nitrogen assisted chemical reduction on the nature of passivation layer, magnetic properties, and Cr (VI) remediation performance of nanoscale zero valent iron

Zero valent iron nanoparticles synthesis through sodium borohydride assisted chemical reduction of iron salts is a well-established and fast synthesis process. Zero valent iron nanoparticles possess a core shell structure due to formation of a surface passivation layer and this layer is composed of iron oxides and hydroxides. Depending on the synthesis condition the thickness of the passivation layer varies and effective electron transfer process from the metallic core to the outer surface is restricted if the passivation layer is too thick. Here in this work a liquid nitrogen assisted zero valent iron nanoparticles synthesis is illustrated which is fast, cheap, and highly scalable process to tune the physicochemical properties of the passivation layer and thus overall performance of zero valent iron nanoparticles. Zero valent iron nanoparticles nucleated under liquid nitrogen (ZLN) has passivation layer thickness in the range 3–4 nm and showed higher magnetic saturation value (145.32 emu/g) and better Cr (VI) reduction performance than its room temperature counterpart ZRT with a passivation layer thickness in the range 6 − 7 nm. The spherical ZLN nanoparticles showcased a particle size distribution profile in the range 10–120 nm and were able to reduce the concentration of 10 ppm Cr (VI) in about 15 min for a ZLN loading of 1 g/L at a pH value of 7.

Artificial neural network for mechanism identification and process prediction of the nanoclusters deagglomeration in the in-line HSM

A multiple-input multiple-output artificial neural network (ANN) for the mechanism identification of nanoclusters deagglomeration and the prediction of particle size distribution (PSD) evolution of nanocluster in deagglomeration process of in-line high shear mixer (HSM) was successfully established. It can successfully realize the description of nanoclusters deagglomeration process within single or multiple processing batches. Besides, this ANN model also can realize the accurate prediction of the d32 of fine and coarse agglomerates, and the fines fraction, at different operating conditions and structural parameters, within the relative error of 10 % and 20 % respectively. Meanwhile, 3D profiles of PSD versus different operating conditions and structural parameters were output by the established ANN model, which were useful for parameter selection of in-line HSM to realize efficient production of nanoparticles suspension. The successful establishment of this ANN model provides an effective, flexible, and advanced intelligent method for guiding the parameter selection of in-line HSM, for realizing the controllable and efficient production of the high-end nanoparticle products with specific particle characteristics.

Investigation into the Size Distribution of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;- ZnO Nanoparticles Dispersed in DI Water and Following the Impact of CNTs on the Stability, Heat Transfer, and Electricity Transfer of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;- ZnO-CNT Hybrid Nanofluid

The stability of dispersed nanoparticles in the base fluid has always been one of the most important challenges in using nanofluids as a coolant in heat transfer applications in different industries such as modern electronic equipment, heat exchangers, solar technologies, etc. In the present study, the dynamic light scattering (DLS) method is used to obtain the particle size distribution of Al2O3-ZnO dispersed in DI water. After adjusting the optical arrangement and designing the DLS setup, the correlation curves are plotted by analyzing the detected signals of the experiments. Then, a decay rate is derived by fitting an exponential function to the correlation curve to get the particle size distribution by using the Stoke-Einstein equation. In order to investigate the stability of Al2O3-ZnO water-based nanofluid, the particle size distribution profiles are studied several times. In addition, the stability of Al2O3-ZnO-CNT hybrid nanofluid is followed by absorbance measurements using a UV-Vis spectrophotometer. Moreover, the thermal conductivity coefficient and electrical conductivity of the Al2O3-ZnO hybrid nanofluid with and without CNT particles are determined by utilizing KD2 Pro and PCT-407 devices, respectively. The results showed that the peak in the particle size distribution curve for Al2O3-ZnO hybrid nanofluid shifted from 476 nm to 128 nm after 5 days. Furthermore, the inclusion of carbon nanotubes increased the stability of zinc oxide particles in the nanofluid. In addition, by adding carbon nanotubes in a ratio of 1:1:0.5 to Al2O3-ZnO nanofluid and forming 0.05 wt.% hybrid nanofluid, the thermal conductivity coefficient was enhanced by 30% in comparison with deionized water, while a 0.05 wt.% hybrid nanofluid without CNT particles improved the thermal conductivity by 19%. Although the electrical conductivity increased by adding nanoparticles to the base fluid, it didn’t change significantly for nanofluids containing CNTs compared to nanofluids without CNT particles.

Localized Electrochemical Performance Degradation in Polymer Electrolyte Fuel Cells (PEFCs)

Pt electrocatalyst durability in polymer electrolyte fuel cells (PEFCs) is generally evaluated through an accelerated stress test (AST); for example, one AST features repeated square-wave cycling with H2/N2 between 0.6 V to 0.95 V vs. reversible hydrogen electrode (RHE) [1]. A separate triangular-wave AST with a higher potential range (1 – 1.5 V vs. RHE) assesses the durability of carbon-based supports [2]. Recent studies [3]–[5] have revealed the heterogeneous nature of cathode catalyst layer degradation. In general, Pt particle size growth mimics the flow field geometry with greater particle size growth under lands compared to channels. Additionally, growth is typically shown to be greater near the air outlet than the inlet and is assumed to be correlated to local performance decay. The impact of such localized degradation on distributed cell performance is investigated in this work. In the present study, a segmented cell is used to quantify functional dependence of local current distributions in aged samples to heterogeneous catalyst layer degradation (Pt particle size growth and carbon support corrosion). The outcome of this enhanced understanding is to identify limiting factors in cell performance at end-of-life (EOL).Single cell studies with 25-cm2 active area are performed using catalyst-coated Nafion® XL membranes (Ion Power Inc.) and SGL-22 BB gas diffusion layers (GDLs) as membrane electrode assembly (MEA) materials and 7-channel serpentine flow field. An S++® current scan shunt (CSS) sensor plate (25-cm2) with 100 current and 25 temperature measurement segments is utilized for current and temperature mapping, respectively. The MEAs are subjected to DOE’s square-wave cycling (0.6 to 0.95 V vs. RHE), triangular-wave cycling (1 to 1.5 V vs. RHE), and a sequence of square-wave cycling followed by triangular-wave cycling. Complete in-situ electrochemical characterization and post-mortem ex-situ diagnostics such as micro-X-ray diffraction (micro-XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are used to obtain particle size distribution and spatial degradation profiles. Results indicate a strong dependence of current distributions on localized catalyst layer degradation. For example, MEA with relatively uniform current distributions at the beginning-of-life (BOL) in Figure 1 exhibits severe mass transport limitations (significantly higher current at the air inlet than the outlet) at EOL when subjected to triangular-wave carbon corrosion AST. Furthermore, an increase of ~1.5x in Tafel slope is observed for the aged sample at EOL, highlighting increased transport losses. These mass transport losses are believed to originate from loss of catalyst layer porosity and subsequent compaction due to carbon support corrosion [2].This work seeks to achieve a greater understanding of the functional dependence between catalyst growth and carbon corrosion and observed local performance.

Nutritional and physical characteristics evaluation of giant panda (Ailuropoda melanoleuca) milk in comparison with bovine and caprine milk

The odour, particle size distribution, microstructure and nutrient profile of giant panda milk (GPM) was compared with bovine milk (BM) and caprine milk (CM). SDS-PAGE images of GPM showed clear, deep and uncertain bands different from those for BM and CM. GPM displayed significantly higher levels for free amino acids (p < 0.05), as well as more polyunsaturated and monounsaturated fatty acids. An electronic nose distinguished the three samples; GPM had the strongest response values to sensors. The effective diameter and polydispersity index of GPM were significantly higher than BM and CM (p < 0.05), and the same results were also observed in confocal laser scanning microscopy (CLSM) images. A giant panda milk substitute formulation with the following main nutrients is recommended: protein, 36%; fat, 50%; carbohydrates, 8%. It is also necessary to supplement a small quantity of isoglobotriose, and adjust the milk substitute amino acids and fatty acids ratios.

Nanoemulsion supported microemulsion electrokinetic chromatography coupled with selected preconcentration techniques as an approach for analysis of highly hydrophobic compounds

In this paper, an oil-in-water (O/W) nanoemulsion (NE) prepared by water cold dilution of an O/W microemulsion (ME) was introduced as a sample matrix in microemulsion electrokinetic capillary chromatography (MEEKC) for the highly hydrophobic compounds analysis. Several model compounds with log PO/W values in the 4.1–10.9 range, from different chemical groups, including retinol, α-tocopherol, cholecalciferol, phylloquinone, menaquinone-7, dichlorodiphenyltrichloroethane, ivermectin have been tested. As a proof of the concept of NE formation, a dynamic light scattering technique was employed to determine the size distribution profile of NE particles. Moreover, due to relatively low conductivity of the NE matrix (50–100 times lower in comparison to the separation buffer) and a negative electric charge provided to hydrophobic compounds through NE dispersed phase, NE matrices have been combined with preconcentration techniques based on electrokinetic dosing, namely field amplified sample injection (FASI) and pressure assisted electrokinetic injection (PAEKI). The detection limits for vitamin K1 and K2-MK7 in the NE matrix in combination with FASI (NE–MEEKC–FASI) as well as PAEKI (NE–MEEKC–PAEKI) were up to 42.9 and 12.1 ng mL−1, respectively. In comparison to standard hydrodynamic injection for microemulsion sample matrix NE–MEEKC–PAEKI grant 45-fold improvement in signal sensitivity. The study presents an innovative approach, as it enables the use of preconcentration techniques for highly hydrophobic compounds (log PO/W > 4), which was not previously possible for implementation in the electromigration techniques. Likewise, the use of organic solvents has been reduced by using ME as a solvent for stock solutions and diluting with water prior to the analysis. The application to real samples was investigated using a dietary supplement containing vitamin K2-MK7 obtained from the fermentation product of soybeans.

Tracing Unconfined Nearfield Spreading of a River Plume Interflow in a Large Lake (Lake Geneva): Hydrodynamics, Suspended Particulate Matter, and Associated Fluxes

River inflows have a major influence on lake water quality due to their input of sediments, nutrients and contaminants. After leaving the river channel, river waters form a plume and interact with ambient lake waters. Strong hydrodynamic changes take place in the nearfield. To determine the nearfield hydro-sedimentary dynamics of the negatively-buoyant Rhône River plume in thermally stratified Lake Geneva, field campaigns were carried out at high and intermediate river discharge. High-resolution full-depth Acoustic Doppler Current Profiler (ADCP) transects were taken at 400, 800, 1,200, and 1,500 m from the river mouth, combined with profiles of temperature, turbidity and particle size distribution. These measurements provided, for the first time in a lake, detailed velocity fields across the full-plume cross-section in each transect. Furthermore, the unique combination of measurement techniques allowed the quantification of entrainment, Suspended Particulate Matter (SPM) concentrations and fluxes. They revealed that the negatively buoyant river inflow intruded into the metalimnion as a laterally unconfined interflow and continued flowing straight out in the streamwise direction, since currents in the lake were weak. At the same time, it mainly spread laterally due to entrainment of ambient water. The size of the interflow core and its velocity progressively decreased with distance from the mouth, as did SPM concentrations and volumes of particles (by a factor of 2–3 within 1,500 m), due to sediment settling and entrainment. The interflow momentum flux remained constant along the pathway, but interflow cross sections and discharge increased 2–3 times (within 1,500 m). The entrainment coefficient was &amp;gt;2 at 400 m and further increased non-linearly along the pathway. These values are much higher than those reported for laterally confined laboratory studies. The particle size distribution in the interflow was dominated by fine particles (&amp;lt;32 μm), which were transported up to 1,500 m from the mouth and most likely beyond, whereas larger particles (&amp;gt;62 μm) almost completely settled out before reaching that distance. The above processes occurred independent of river discharge; their intensity, however, changed with discharge.

Intensifying Continuous Production of Gag-HA VLPs at High Cell Density Using Stable Insect Cells Adapted to Low Culture Temperature.

Protein production processes based on stable insect cell lines require intensification to be competitive with the insect cell-baculovirus expression vector system (IC-BEVS). High cell density (HCD) cultures operate continuously, capable of maintaining specific production rates for extended periods of time which may lead to significant improvements in production yields. However, setting up such processes is challenging (e.g., selection of cell retention device and optimization of dilution rate), often demanding the manipulation of large volumes of culture medium with associated high cost. In this study, we developed a process for continuous production of Gag virus–like particles (VLP) pseudotyped with a model membrane protein (influenza hemagglutinin, HA) at HCD using stable insect cells adapted to low culture temperature. The impact of the cell retention device (ATF vs. TFF) and cell-specific perfusion rate (CSPR) on cell growth and protein expression kinetics was evaluated. Continuous production of Gag-HA VLPs was possible using both retention devices and CSPR of 0.04 nL/cell.d; TFF induces higher cell lysis when compared to ATF at later stages of the process (kD = 0.009 vs. 0.005 h−1, for TFF and ATF, respectively). Reducing CSPR to 0.01–0.02 nL/cell.d using ATF had a negligible impact on specific production rates (rHA = 72–68 titer/109 cell.h and rp24 = 12–11 pg/106 cell.h in all CSPR) and on particle morphology (round-shaped structures displaying HA spikes on their surface) and size distribution profile (peaks at approximately 100 nm). Notably, at these CSPRs, the amount of p24 or HA formed per volume of culture medium consumed per unit of process time increases by up to 3-fold when compared to batch and perfusion operation modes. Overall, this work demonstrates the potential of manipulating CSPRs to intensify the continuous production of Gag-HA VLPs at HCD using stable insect cells to make them an attractive alternative platform to IC-BEVS.

Heat treatment of liquid ultrafiltration concentrate influences the physical and functional properties of milk protein concentrate powders

Liquid milk protein concentrate (MPC; 18.3 and 16.5%, w/w, total solids and protein, respectively) was heat treated at 80 °C (low-heat), 100 °C (medium-heat) and 120 °C (high-heat) for 30 s, or did not undergo heat treatment (control), prior to spray drying. Viscosity of the liquid MPC increased with increasing heat treatment temperature. Physical properties of MPC powders were influenced by heat treatment, with the size of powder particles generally increasing with increasing temperature. Heat treatment of ultrafiltration concentrate influenced the heat stability of MPC powders, with high-heat treated MPC having highest heat stability at pH 6.9 and 7.0 (140 °C). However, particle size distribution profiles showed a decrease in powder dispersion with increased heat treatment temperature. This study demonstrated that heat treatment of ultrafiltration concentrate at temperatures ≥100 °C can present challenges with solubilising subsequent MPC powders.

Bioanalytics for Influenza Virus-Like Particle Characterization and Process Monitoring.

Virus-like particles (VLPs) are excellent platforms for the development of influenza vaccine candidates. Nonetheless, their characterization is challenging due to VLPs’ unique biophysical and biochemical properties. To cope with such complexity, multiple analytical techniques have been developed to date (e.g., single-particle analysis, thermal stability, or quantification assays), most of which are rarely used or have been successfully demonstrated for being applicable for virus particle characterization. In this study, several biophysical and biochemical methods have been evaluated for thorough characterization of monovalent and pentavalent influenza VLPs from diverse groups (A and B) and subtypes (H1 and H3) produced in insect cells using the baculovirus expression vector system (IC-BEVS). Particle size distribution and purity profiles were monitored during the purification process using two complementary technologies — nanoparticle tracking analysis (NTA) and tunable resistive pulse sensing (TRPS). VLP surface charge at the selected process pH was also assessed by this last technique. The morphology of the VLP (size, shape, and presence of hemagglutinin spikes) was evaluated using transmission electron microscopy. Circular dichroism was used to assess VLPs’ thermal stability. Total protein, DNA, and baculovirus content were also assessed. All VLPs analyzed exhibited similar size ranges (90–115 nm for NTA and 129–141 nm for TRPS), surface charges (average of −20.4 mV), and morphology (pleomorphic particles resembling influenza virus) exhibiting the presence of HA molecules (spikes) uniformly displayed on M1 protein scaffold. Our data shows that HA titers and purification efficiency in terms of impurity removal and thermal stability were observed to be particle dependent. This study shows robustness and generic applicability of the tools and methods evaluated, independent of VLP valency and group/subtype. Thus, they are most valuable to assist process development and enhance product characterization.

Physical and chemical characterization of fugitive particulate matter emissions of the iron and steel industry

The iron and steel industry is a notable particulate matter emitter. In source apportionment of particulate matter, it is important to identify the characteristics of particulate matter originating from steel sites. However, previous studies mostly focus on stack emission sources, while few reports on fugitive emission sources are available. Aiming to fill this gap, the physical and chemical characteristics of fugitive emission sources in the whole iron and steel production process were explored. The emission factor, particle size distribution (PSD), and morphological and chemical profiles of fugitive particulate matter (FPM) originating from fugitive emission sources at the observed site were analyzed through on-site sampling and in-lab testing. The emission factors in descending sequence are those of steelmaking plants, sinter plants, ironmaking plants and coking plants. The particle size of FPM mainly ranges from 0.1 to 716 μm, while distribution forms with both unimodal and bimodal peaks occur. The microscopic morphology of FPM is mainly divided into: irregular Fe-, Si-, Ca- and Mg-rich mineral particles formed by physical means, layered carbonaceous particles formed by mechanical crushing and combustion cracking, spherical Si-, Al- and Fe-rich particles in a high-temperature molten state, and chain and agglomerate particles formed by the polymerization of high-temperature flue gas and volatile minerals. The mass fraction of Fe ranks first in the sintering, ironmaking, and steelmaking processes, with values ranging from 1.40% to 57.79%. C attains the highest mass fraction, 69.80%, in the PFM originating from crushing mills.