Size Distribution Measurements Research Articles

Identification of a population balance model for Streptococcus thermophilus

The identification of a cell population balance model for the fermentation of the lactic acid bacterium Streptococcus thermophilus based on experimental data is addressed. As a starting point, a mass balance model is parameterized and then cell division rates identified exploring data from cell size distribution measurements as well as microscope images. The particular problem lies in the fact that Streptococcus th. grows in chains build up during cell division in dependence on physico-chemical parameters like lactic acid concentration, while cell size distribution (CSD) measurements do not clearly distinguish between cell and chain size. It is shown that, by using a factorized function for the cell division rate that reflects these different effects and can be identified using experimental data, it is possible to obtain an adequately parameterized model that is able to predict the time evolution of the CSD, opening the path for different process monitoring and control schemes.

Measurement of Bubble Size Distribution and Generation Position of Bubbles Generated during Smelting Reduction of Iron Oxide-containing Slag

Measurement of Bubble Size Distribution and Generation Position of Bubbles Generated during Smelting Reduction of Iron Oxide-containing Slag

Measurements of Raindrop Size Distribution Using Collocated X- and Ka-Band Radars in the Western Ghats

Measurements of Raindrop Size Distribution Using Collocated X- and Ka-Band Radars in the Western Ghats

Implications for new particle formation in air of the use of monoethanolamine in carbon capture and storage.

Alkanolamines are currently being deployed in carbon capture and storage (CCS) technology worldwide, and atmospheric emissions have been found to coincide with locations exhibiting elevated concentrations of methanesulfonic acid (MSA). It is thus critical to understand the fate and potential atmospheric reactions of these chemicals. This study reports the characterization of sub-10 nm nanoparticles produced through the acid-base reaction between gas phase monoethanolamine (MEA) and MSA, a product of organosulfur compound oxidation in air, using a flow reactor under dry and humid (up to ∼60% RH) conditions. Number size distribution measurements show that MEA is even more efficient than methylamine in forming nanoparticles on reaction with MSA. This is attributed to the fact that the MEA structure contains both an -NH2 and an -OH group that facilitate hydrogen bonding within the clusters, in addition to the electrostatic interactions. Due to this already strong H-bond network, water has a relatively small influence on new particle formation (NPF) and growth in this system, in contrast to MSA reactions with alkylamines. Acid/base molar ratios of unity for 4-12 nm particles were measured using thermal desorption chemical ionization mass spectrometry. The data indicate that reaction of MEA with MSA may dominate NPF under some atmospheric conditions. Thus, the unique characteristics of alkanolamines in NPF must be taken into account for accurate predictions of impacts of CCS on visibility, health and climate.

Unraveling Contributions from Combustion, Secondary, Traffic, and Dust Sources through Particle Mass Size Distribution Measurement

Unraveling Contributions from Combustion, Secondary, Traffic, and Dust Sources through Particle Mass Size Distribution Measurement

Error analysis of green pellet size distribution measurement on conveyors using simulation method

Error analysis of green pellet size distribution measurement on conveyors using simulation method

Enhancing the dewatering of oil sands mature fine tailings by coagulation-flocculation and pressure filtration with tannic acid-mediated polymeric complex network

This study presents a new method to improve the dewatering efficiency of oil sands mature fine tailings (MFT) by pressure filtration using a tannic acid-mediated polymeric complex network as a flocculant. It was found that the prior addition of tannic acid ahead of poly(ethylene oxide) and ferric chloride significantly increased the vacuum filtration rate by improving the permeability of the filter cake and reducing its specific resistance to filtration. The beneficial role of tannic acid was investigated by slurry shear stress, sedimentation, floc morphology and size distribution measurements, and UV–Vis and FTIR spectroscopic characterization. Results indicated that tannic acid acted as a crosslinker to complex with both poly(ethylene oxide) and ferric chloride to develop a tri-component polymeric network. Within the network, numerous hydrogen bonds and coordination bonds enabled a sufficient crosslinking density, resulting in higher floc strength and compression resistance. Flocs generated by the tannic acid-mediated polymeric network were more rigid with an expanded structure, allowing drainage channels to remain open in the filter cake for better permeability. Scale-up experiments on a Millipore pressure filtration unit verified the beneficial role of tannic acid in filtering the mature fine tailings, achieving a much higher net water release rate and cake solid content.

The Impact of Flocculation on In Situ and Ex Situ Particle Size Measurements by Laser Diffraction

AbstractAccurate particle size distribution (PSD) measurements of suspended particulate matter (SPM) composed of flocs and aggregates are important to improve understanding of ecological and geomorphological processes, and for environmental engineering applications. PSDs can be measured in situ (in the field) using a submersible sensor, or ex situ (in the laboratory) using samples. The methodological choice is often guided by logistical factors, and the differences in PSDs acquired by in situ and ex situ measurements is of concern. In this study, a laser‐diffraction instrument (the LISST‐200X) was used to compare in situ and ex situ PSD measurements. Samples measured ex situ were stored for three consecutive weeks and measured each week in a laboratory using different stirrer speeds. We observed that ex situ measurements display a higher D50 (median particle size) than in situ measurements of the same sample (up to 613% larger, 112% on average). Our experiments show that the difference between in situ and ex situ measurements can be explained by flocculation of the riverine sediments during the first week of storage. During the subsequent ex situ measurements, the stirring results in a significantly lower D50. Ex situ measurements are therefore unsuitable for flocculated SPM. This study provides recommendations for optimizing PSD measurements by calculating the measurement times required to obtain robust PSD measurements (exceeding 3 min per sample), which are larger for field samples with coarser particles and wider PSDs.

Hyperbranched polymer nanocomposite as a potential shale stabilizer in water-based drilling fluids for improving wellbore stability

Shale hydration has been a frequent and challenging technical problem causing wellbore instability in oil and gas drilling processes. The aim of this study is to design a novel hyperbranched polymer nanocomposite (HBPN) based on a synergistic strategy of physical plugging and chemical inhibition to improve wellbore stability. The inhibitive property of HBPN was comprehensively evaluated through the sodium montmorillonite (Na-MMT) plates immersion test, capillary suction time (CST) test, and shale hot-rolling recovery test. Results implied that HBPN presented better inhibition performance. The shale hydration rate was reduced to 0.03 in the presence of HBPN. Particularly, the shale hot-rolling recovery rate reached 80.54 % at 150 °C and presented long-term shale inhibition durability. It demonstrated excellent plugging performance in the artificial low permeability filter cakes plugging test, reaching a plugging efficiency of 42.45 % with the addition of 2.0 w/v% HBPN. The potential mechanism of action of HBPN was proposed through particle size distribution (PSD) measurement, Zeta (ζ) potential measurement, Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) analysis. The coordination of electrostatic interaction and hydrogen bonding impelled a decrease in the ζ potential and interlayer spacing of Na-MMT. Meanwhile, HBPN could embed into formation pores and fractures to establish a tight plugging zone. This approach outlined herein might provide an avenue to strengthen wellbore stability for the drilling industry.

Impact of desert dust on new particle formation events and the cloud condensation nuclei budget in dust-influenced areas

Abstract. Detailed knowledge on the formation of new aerosol particles in the atmosphere from precursor gases, and their subsequent growth, commonly known as new particle formation (NPF) events, is one of the largest challenges in atmospheric aerosol science. High pre-existing particle loadings are expected to suppress the formation of new atmospheric aerosol particles due to high coagulation and condensation (CS) sinks. However, NPF events are regularly observed in conditions with high concentrations of pre-existing particles and even during intense desert dust intrusions that imply discrepancies between the observations and theory. In this study, we present a multi-site analysis of the occurrence of NPF events under the presence of desert dust particles in dust-influenced areas. Characterization of NPF events at five different locations highly influenced by desert dust outbreaks was done under dusty and non-dusty conditions using continuous measurements of aerosol size distribution in both fine and coarse size fractions. Contrary to common thought, our results show that the occurrence of NPF events is highly frequent during desert dust outbreaks, showing that NPF event frequencies during dusty conditions are similar to those observed during non-dusty conditions. Furthermore, our results show that NPF events also occur during intense desert dust outbreaks at all the studied sites, even at remote sites where the amounts of precursor vapours are expected to be low. Our results show that the condensation sink associated with coarse particles (CSC) represents up to the 60 % of the total CS during dusty conditions, which highlights the importance of considering coarse-fraction particles for NPF studies in desert-dust-influenced areas. However, we did not find a clear pattern of the effect of desert dust outbreaks on the strength of NPF events, with differences from site to site. The particle growth rate (GR) did not present a clear dependence on the CS during dusty and non-dusty conditions. This result, together with the fact that desert dust has different effects on the growth and formation rates at each site, suggests different formation and growth mechanisms at each site between dusty and non-dusty conditions, probably due to differences in precursor vapours' origins and concentrations as well as changes in the oxidative capacity of pre-existing particles and their effectiveness acting as CS. Further investigation based on multiplatform measurement campaigns and chamber experiments with state-of-the-art gaseous and particulate physical and chemical properties measurements is needed to better understand the role of catalyst components present in desert dust particles in NPF. Finally, our results reveal a significant impact of NPF events on the cloud condensation nuclei (CCN) budget during desert dust outbreaks at the studied sites. Therefore, since desert dust contributes to a major fraction of the global aerosol mass load, and since there is a foreseeable increase in the frequency, duration and intensity of desert dust episodes due to climate change, it is imperative to improve our understanding of the effect of desert dust outbreaks on NPF and the CCN budget for better climate change prediction.

Impact of Metallic Impurities on the Synthesis and Properties of NMC Cathode Material Obtained by Co-Precipitation

Among the different factors that influence lithium-ion batteries (LIB) performances, the properties of the cathode active material (CAM) play a crucial role. The composition, the crystallinity and also the particle size and morphology of these materials are part of the major parameters governing the CAM behaviour. These parameters are strongly dependent of the synthesis method, especially in the case of the hydroxide precursor of the layered LiNixMnyCozO2 [1].One of the most widely spread synthesis method of such precursors is the synthesis by co-precipitation, where metal salts of Ni, Mn and Co are precipitated together in a continually-stirred tank reactor (CSTR) in carefully controlled pH- and temperature conditions[2]. Any parameter of the co-precipitation must be precisely tuned to obtain the desired material, as highlighted in the figure here after.Considering the increasing presence of wanted (coating/doping)[3] and unwanted (impurities after recycling)[4] elements in the co-precipitation process, extensive knowledge of their impact on it is of great interest. Therefore, the synthesis of NixMnyCoz(OH)2 was conducted by co-precipitation with the controlled addition of increasing amounts of elements such as Cu and Al.The effects of these additions were investigated by thoroughly characterizing the morphology of the obtained hydroxides with the help of SEM, BET, particle size distribution and porosity measurements. The composition of the synthesized hydroxides was determined by the ICP-OES technique. The possible influence on the further step of CAM synthesis, i.e. calcination, was followed by in-situ X-Ray thermodiffraction and the electrochemical performances were assessed by galvanostatic cycling the obtained CAM in lithium half-cells. This helped to evidence the varying impact of the added elements, depending on their concentration in the synthesis process.This work is supported by the German Ministry for Economy and Climate Protection (BMWK).

Hierarchically Structured Potassium-Vanadium-Phosphate/C Composites As Possible High-Voltage Cathodic Materials for Potassium-Ion-Batteries

Potassium-ion-batteries (PIBs) share technological similarities with Lithium- and Sodium-ion batteries (LIBs/SIBs) and are based on the inter- and deintercalation of K ions between two host materials.[1] The higher atomic weight and larger ionic radius of potassium ions results in lower gravimetric and volumetric capacities compared to LIBs.[2] But they offer similar advantages as SIBs (i.e. use of aluminium as current collector on both sides, evenly distributed potassium reserves) as well as graphite could be used as anode.[2,3] Also, they are expected to offer higher cell voltages due to the low standard potential of K/K+ vs. SHE of -2.93V.[3] To unlock the full potential of PIBs, cathode materials with high average potentials above 4 V need to be developed, which would significantly improve the energy density.[4] Polyanionic compounds, especially different Vanadium-Phosphates, are prepared and investigated for this purpose. Their thermal stability and diverse structural chemistry are advantageous for high energy PIBs. [2,5] One of the often-used synthesis methods for polyanionic compounds is the solid-state reaction. [4] In my work this well-known synthesis was coupled with a spray-drying process and a subsequently sintering process for K3V2(PO4)3/C composites. This created spherical secondary particles with a size in the micrometer range and an open micro-porosity. (see attached image)Through the addition of different amounts of organic sugars as a carbon source during the synthesis or sintering step an additional carbon coating of the primary and secondary particles was achieved, as well as the morphology of the secondary particles could be influenced. The influences of the different carbon contents during synthesis and sintering were investigated by thoroughly characterizing the morphology and crystal structure of the secondary particle with the help of SEM, BET, particle size distribution, XRD and porosity measurements. First electrochemical evaluation of the synthesized material was done by galvanostatic cycling the KVP/C composites against potassium.

Determination of Protein Amount in Nanosized Synthetic Liposomes by Surface Effect Raman Spectroscopy (SERS)

Accurate characterization of synthetic liposomes is essential since they give information about the vesicu-lar structures in bodily fluids such as extracellular vesicles. The characterization tasks are generally the determination of the sizes of the liposomes and the profiling of the liposomes' content. Optical tweezers and Surface Enhanced Raman Spectroscopy (SERS) were used to profile the nanosized liposomes. The size distribution of the trapped liposomes (140 nm on average) was found by using Einstein's Brownian motion equation, consistent with the size distribution obtained from dynamic light scattering measure-ments. Besides, Gramicidin-encapsulated liposomes were measured using SERS, and statistically signifi-cant differentiation was found in Raman intensities between liposome populations with altering concentra-tions of proteins. This study uniquely measured size distributions of nano-sized liposomes with conven-tional optical tweezers (without plasmonics) and determined the chemical differences between empty and protein encapsulated liposomes with high accuracy using Raman spectroscopy

(Invited) Formation and Characterization of Fe-Silicide Nanodots for Optoelectronic Application

Light emission from group-IV based nanostructures has been attracting much attention in the field of Si-based photonics because of its potential to combine photonic processing with electronic processing on a single chip [1]. Among various Fe-silicides, semiconducting β-FeSi2 shows light emission in the near-infrared region [2, 3] and is one of promising materials in optoelectronic application from viewpoints of tuning emission energy and improving luminous efficiency by means of quantized structures. In this work, we focus on low temperature formation of β-FeSi2 nanodots (NDs) over ~1011 cm-2 in areal density on SiO2 and the characterization of light emission properties of β–FeSi2 NDs.After conventional wet-chemical cleaning steps of p-type Si(100) substrates, a ~300-nm-thick SiO2 layer was grown at 1000°C in dry O2 and followed by dipping shortly in a dilute HF solution to make uniform surface termination with Si-OH bonds. After that, Fe films in the thickness range from 1.0 to 3.0 nm were formed on the OH-terminate SiO2 layer by electron beam evaporation without any extra heating. And then, the Fe–films were exposed to remote plasma of pure H2 (H2-RP) at 400°C to form highly-dense Fe-NDs [4]. Subsequently, so-prepared Fe-NDs were exposed to pure SiH4 at 400°C while controlling the amount of SiH4 exposure by duration and pressure.AFM images taken after exposure of Fe-films to H2-RP confirm the high-density formation of well-defined NDs. In the cases of H2-RP exposure of 1.3-nm-thick and 3.0-nm-thick Fe-films, the areal dot densities as high as ~1.1 × 1011 and ~1.3 × 1011 cm−2 were obtained, respectively, in which the average dot-heights of self-assembled Fe-NDs were determined to be ~5.3 and ~10.9 nm, respectively, by fitting a log-normal function to each measured size distribution. Notice that AFM images taken after SiH4 exposure show almost no change in the areal dot density while a slight increase in the average dot height. From cross-sectional transmission electron microscope images, we have also verified the formation of distorted-spherical shape NDs with a lattice spacing of ~0.18 nm associated with β-FeSi2. And the result is well consistent with the chemical composition of NDs after SiH4 exposure as evaluated by x-ray photoelectron spectroscopy. In addition, with 976 nm light excitation using a semiconductor laser, the NDs after the SiH4 exposure show stable photoluminescence (PL) signals in the energy region from ~0.7 to ~0.9 eV even at room temperature. On the other hand, no PL signals were detected from the NDs before the SiH4 exposure and after Ar anneal at 400°C. Also, when the size of the Fe-silicide NDs was increased from ~5.3 to ~10.9 nm in average dot height by increasing the initial Fe-film thickness, a distinct red-shift in PL was clearly observed. Thus, the observed PL can be interpreted in terms of radiative recombination of photogenerated carriers through quantized states of β-FeSi2 NDs. These results indicate that SiH4 exposure to Fe-NDs formed on SiO2 is a very promising technique for the low-temperature fabrication of luminescent FeSi2 NDs.AcknowledgementThis work was supported in part by Grant-in-Aid for Scientific Research (A) 21H04559 of MEXT Japan, and the Cooperative Research Project Program of the Research Institute of Electrical Communication, Tohoku University.

Permeability of sandy soils estimated from particle size distribution and field measurements

Permeability of sandy soils estimated from particle size distribution and field measurements

Development of quantitative precipitation estimation (QPE) relations for dual-polarization radars based on raindrop size distribution measurements in Metro Manila, Philippines

Quantitative precipitation estimates (QPE) can be further improved using estimation algorithms derived from localized raindrop size distribution (DSD) observations. In this study, DSD measurements from two disdrometer stations within Metro Manila during the Southwest monsoon (SWM) period were used to investigate the microphysical properties of rainfall and develop localized dual-polarimetric relations for different radar bands and rainfall types. Observations show that the DSD in Metro Manila is more distributed to larger diameters compared to Southern Luzon and neighboring countries and regions in the Western Pacific. This is reflected by the relatively higher mass-weighted mean diameter (Dm) and smaller shape (μ) and slope (Λ) parameters measured in the region. The average values of Dm and normalized intercept parameter (Nw) in convective rain samples also suggest that convective rains in Metro Manila are highly influenced by both continental and oceanic convective processes. Dual-polarimetric variables simulated using the T-matrix scattering method showed good agreement with disdrometer-derived reflectivity (ZH) values. The 0.5 dB and 0.3° km−1 thresholds for the differential reflectivity (ZDR) and specific differential phase (KDP) based on the blended algorithm of Cifelli (J Atmos Ocean Technol 28:352-364, 2011) and Thompson et al. (2017) are proven to be useful since the utility of the dual-polarimetric variables as rainfall estimators are shown to have dependencies on the radar band and rainfall type. Evaluation of the QPE products with respect to the C-band shows that R (KDP, ZDR) has the best performance among the dual-pol relations and statistically outperformed the conventional Marshall & Palmer relation [R(ZMP)]. The results show that dual-polarimetric variables such as ZDR and KDP can better represent the DSD properties compared to one-dimensional Z, hence providing more accurate QPE products than the conventional R(Z) relations.

Seasonal variations in composition and sources of atmospheric ultrafine particles in urban Beijing based on near-continuous measurements

Abstract. Understanding the composition and sources of atmospheric ultrafine particles (UFPs) is essential in evaluating their exposure risks. It requires long-term measurements with high time resolution, which are scarce to date. We performed near-continuous measurements of UFP composition during four seasons in urban Beijing using a thermal desorption chemical ionization mass spectrometer, accompanied by real-time size distribution measurements. We found that UFPs in urban Beijing are dominated by organic components, varying seasonally from 68 % to 81 %. CHO organics (i.e., molecules containing carbon, hydrogen, and oxygen) are the most abundant in summer, while sulfur-containing organics, some nitrogen-containing organics, nitrate, and chloride are the most abundant in winter. With the increase of particle diameter, the contribution of CHO organics decreases, while that of sulfur-containing and nitrogen-containing organics, nitrate, and chloride increases. Source apportionment analysis of the UFP organics indicates contributions from cooking and vehicle sources, photooxidation sources enriched in CHO organics, and aqueous/heterogeneous sources enriched in nitrogen- and sulfur-containing organics. The increased contributions of cooking, vehicle, and photooxidation components are usually accompanied by simultaneous increases in UFP number concentrations related to cooking emission, vehicle emission, and new particle formation, respectively, while the increased contribution of the aqueous/heterogeneous composition is usually accompanied by the growth of UFP mode diameters. The highest UFP number concentrations in winter are due to the strongest new particle formation, the strongest local primary particle number emissions, and the slowest condensational growth of UFPs to larger sizes. This study provides a comprehensive understanding of urban UFP composition and sources and offers valuable datasets for the evaluation of UFP exposure risks.

Processing and Properties of ZrB2-Copper Matrix Composites Produced by Ball Milling and Spark Plasma Sintering

Copper matrix composites with zirconium diboride (ZrB2) were synthesised by ball milling and consolidated by Spark Plasma Sintering (SPS). Characterisations of the ball-milled composite powders were performed by scanning electron microscopy (SEM), X-ray diffraction, and measurement of the particle size distribution. The effect of the sintering temperature (1123 K, 1173 K, and 1223 K) and pressure (20 MPa and 35 MPa) on the density, porosity, and Young’s modulus was investigated. The relationship between the change of Orb content and physical, mechanical, and electrical properties was studied. Experimental data showed that the properties of Cu–Orb composites depended significantly on the SPS sintering conditions. The optimal sintering temperature was 1223 K with a pressure of 35 MPa. Composites exhibited a high degree of consolidation. For these materials, the apparent density was in the range of 93–97%. The results showed that the higher content of Orb in the copper matrix was responsible for the improvement in Young’s modulus and hardness with the reduction of the conductivity of sintered composites. The results showed that Young’s modulus and the hardness of the Cu 20% Orb composites were the highest, and were 165 GPa and 174 HV0.3, respectively. These composites had the lowest relative electrical conductivity of 17%.

Comparison of the Flame Dynamics of a Liquid-Fueled Swirl-Stabilized Combustor for Different Degrees of Fuel-Air Premixing

Abstract This study investigates the flame dynamics of lean premixed kerosene combustion for two different degrees of fuel–air premixing using a swirl stabilized burner with an axially movable twin fluid fuel injection nozzle. Thermal power, equivalence ratio, and atomizing air mass flow are varied systematically for both nozzle positions investigated. Measurements of the droplet size distribution at the nozzle exit are provided for all operation points. NOx emission measurements and OH*-chemiluminescence flame images show that stationary combustion characteristics significantly change with the nozzle position. Flame Transfer Functions (FTFs) are presented and interpreted for all operation points. The FTFs for the two configurations differ most in the low frequency range where the influence of the droplet dynamics is expected to be highest. For both configurations, a change in thermal power does not affect droplet size, flame shape, NOx emissions, and FTF. The observed trends in response to changes in equivalence ratio and atomizing air mass flow are opposite for both configurations. NOx emissions and flame shape are independent of the atomization air mass flow in the highly premixed configuration but not in the partially premixed configuration. In contrast to this, the FTF is affected by changes of the atomization air mass flow in both configurations, but again the trends are opposite. The observed trends for the highly premixed configuration are modeled and reproduced by a change in the phase relation between the equivalence ratio fluctuations and other instability driving mechanisms.

Quantifying the dependence of drop spectrum width on cloud drop number concentration for cloud remote sensing

Abstract. In situ measurements of liquid cloud and precipitation drop size distributions from aircraft-mounted probes are used to examine the relationship of the width of drop size distributions to cloud drop number. The width of the size distribution is quantified in terms of the parameter k=(rv/re)3, where rv is the volume mean radius and re is the effective radius of the distributions. We find that on small spatial scales (∼100 m), k is positively correlated with cloud drop number. This correlation is robust across a variety of campaigns using different probe technology. A new parameterization of k versus cloud drop number is developed. This new parameterization of k is used in an algorithm to derive cloud drop number in liquid phase clouds using satellite measurements of cloud optical depth and effective radius from the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor on Aqua. This algorithm is compared to the standard approach to derive drop number concentration that assumes a fixed value for k. The general tendency of the parameterization is to narrow the distribution of derived number concentration. The new parameterization generally increases the derived number concentration over ocean, where N is low, and decreases it over land, where N is high. Regional biases are as large as 20 % with the magnitude of the bias closely tracking the regional mean number concentration. Interestingly, biases are smallest in regions of frequent stratocumulus cloud cover, which are a regime of significant interest for study of the aerosol indirect effect on clouds.