Particle Size Estimation Research Articles

A novel nucleic acid based bio-assay toward recognition of Haemophilus influenza using bioconjugation and DNA hybridization method

Haemophilus influenza (H. influenza) is a gram negative coccobacillus pathogenic microorganism. H. influenza produces beta-lactamases, and it is also able to modify its penicillin-binding proteins, so it has gained resistance to the penicillin family of antibiotics. In this work, a novel sensitive approach was established for the monitoring of H. influenza using DNA based bio-assay. For the first time, specific sequence of thiolated probe of Haemophilus influenza (SH-5′-AAT TTT CCA ACT TTT TCA CCT GCA T-3′) was immobilized on the surface of gold (Au) electrode. Square wave voltammetry (SWV) was carried out in toluidine blue (TB) solution for DNA hybridization and targeting of cDNA sequence of Haemophilus influenza. Field scanning electron microscope (FE-SEM) was applied to investigation of the electrode morphology and estimate of particle size. In the optimal conditions, the planned strategy could detect target DNA (5′-ATG CAG GTG AAA AAG TTG GAA AAT T-3′) down to 1 ZM with a linear range from 1 μM to 1 ZM. Moreover, engineered geno-assay selectively differentiates the complementary sequence from target sequences with one, double and three base mismatch sequences.

Estimation of Particle Size Distribution from Bulk Scattering Spectra: Validation on Monomodal Suspensions.

A particle size distribution (PSD) estimation method based on light-scattering properties was validated on experimental visible/near-infrared scattering spectra of polystyrene suspensions, with a nominal particle size ranging from 0.1 to 12 μm in diameter. On the basis of μs and g spectra extracted from double integrating sphere measurements, good PSD estimates were obtained for particles ≥1 μm. The particle volume fraction estimates in the case of μs were close to the target concentrations, although influenced by small baseline fluctuations on the spectra. For submicrometer particles, on the other hand, the non-oscillating μs spectra lack discriminating power, resulting in erroneous PSD estimates. The reduced scattering coefficient spectra (μs') were found less useful for particle size estimation as they lack a characteristic shape, causing an over- or underestimation of the distribution width. In summary, the estimation routine proved to deliver PSD estimates in line with the reference measurements for micrometer-sized or larger particles based on their μs and g scattering spectra. Additional validation on more polydisperse samples forms the next step before going to bimodal PSD estimates.

Enhanced Carbon monoxide-sensing properties of Chromium-doped ZnO nanostructures

Low power consumption, fast response and quick recovery times are important parameters for gas sensors performance. Herein, we report the experimental and theoretical studies of ZnO and Cr doped ZnO nanostructures used in low temperature (50 °C) sensors for the detection of CO. The synthesized films were characterized by XRD, UV-Vis, FE-SEM and EDX. The XRD patterns for the ZnO and 0.5 wt% Cr/ZnO films confirm the formation of a single-phase hexagonal wurtzite structure. The reduction of the ZnO optical band gap from 3.12 eV to 2.80 eV upon 0.5 wt% Cr doping is well correlated with the simulation data. The FE-SEM images of the films show spherical morphology with the estimated particle sizes of about ~40 nm and ~ 25 nm were recorded for the ZnO and 0.5 wt% Cr/ZnO films, respectively. Enhanced gas sensing performance is achieved with Cr doping and the sensitivity of ZnO increases from 9.65% to 65.45%, and simultaneously decreasing the response and recovery times from 334.5 s to 172.3 s and from 219 s to 37.2 s, respectively. These improvements in gas sensing performance are due to the reduction in particle size and optical band gap, and an increase in specific surface area.

Possibility of estimating particle size and porosity on Ryugu through MARA temperature measurements

We investigated whether the MASCOT/MARA thermal radiometer can be used to determine regolith particle size and porosity on the asteroid Ryugu in the Hayabusa2 mission. We used a one-dimensional heat flow model and our own thermal conductivity model for regolith to compare MARA's performance and the expected Ryugu surface temperatures of various particle sizes and porosities. The results showed that MARA is capable of constraining particle size with ±30% uncertainty if particle size is near 4.25 mm and near-surface porosity is near 60% (a fraction of void spaces between regolith particles in a unit volume), assuming certain physical properties of regolith particles. The porosity cannot be constrained meaningfully through MARA observations alone; however, it is constrained with uncertainty of ±10% around 50% and ±5% around 70% with 2σ probability if other supportive observations (by the MASCOT camera) provide the particle size. The results also show that nighttime temperature is more sensitive to the particle size and porosity variations and its observation is essential to achieve the small error ranges, while MARA is the only instrument to observe the nighttime temperature on Ryugu. In this study, the surface roughness effect in insolation and thermal radiations was neglected. The roughness effect is presumed to be less influential in nighttime, however, this effect must be carefully considered in actual data analysis of MARA.

Influence of Mixing on the Precipitation of Organic Nanoparticles: A Lagrangian Perspective on Scale‐up Based on Self‐Similar Distributions

AbstractPrecipitation of nanoparticles is applied in various fields with a rising interest in the formulation of poorly soluble drugs. The impact of fluid mixing on the precipitation of organic nanoparticles is analyzed. Direct numerical simulations are applied to determine the spatiotemporal evolution of the liquid phase composition and to estimate the particle evolution along Langragian trajectories. The simulation results are compared with laboratory experiments of mixing and particle size evolution, which use a recently developed approach to rapidly stabilize the precipitated nanoparticles. The impact of mixing on precipitation is revealed, thereby enabling a parameter‐free estimation of the mean particle sizes and the particle size distributions. The distributions of residence time, supersaturation time, and particle size are self‐similar for Reynolds numbers in the turbulent regime and allow the derivation of scale‐up rules.

Li4Ti5O12/AC Hybrid Supercapacitor combining High Power of Supercapacitor and High Energy of Li-ion battery

Abstract Spinel lithium titanate (Li4Ti5O12) has been synthesized by solid state route. Prepared Li4Ti5O12 powder was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) for phase purity and particle size estimation respectively. Hybrid supercapacitor consisting of activated carbon and synthesized Li4Ti5O12 as electrodes is assembled inside the glovebox filled with argon gas. Electrochemical characteristics of hybrid supercapacitor are observed by constant current charging-discharging cyclic voltammetry. Activated carbon based electric double layer capacitor (EDLC) was also prepared and electrochemically characterized for comparison. Hybrid supercapacitor shows better discharge capacities of 12 and 10 mAhg-1 at 0.5C and 1C (1C = 100mAhg-1) compared to 9 and 3 mAhg-1of EDLC respectively. Cyclic performances are also observed for 80 cycles at 2C. The capacity retention of hybrid supercapacitor is >86% compared to 80% of EDLC.

The use of PWHM and Mie methods in estimation of colloidal silver particle size obtained by chemical precipitation with sodium borohydride

Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century, silver is mostly pushed out from conventional medicine. However, with the excessive use of antibiotics, antibiotic-resistant super bacteria have appeared. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride as a reducing agent. As influence factors, color of the solution, Tyndall effect, UV/Vis absorption, and nanoparticle size estimated by PWHM (Peak Width at Half Maximum) and Mie methods were used. By increasing the silver concentration, color of the solution ranged from light yellow to dark yellow. All solutions showed Tyndall's effect equally. By the UV/Vis analysis it was found that the solutions absorbed radiation in the wavelength range 390-402 nm, and the intensity increased with increasing silver nitrate concentrations. By the PWHM and Mie methods silver nanoparticle sizes were estimated in the range 12-20 nm.

Data driven particle size estimation of hematite grinding process using stochastic configuration network with robust technique

As a production quality index of hematite grinding process, particle size (PS) is hard to be measured in real time. To achieve the PS estimation, this paper proposes a novel data driven model of PS using stochastic configuration network (SCN) with robust technique, namely, robust SCN (RSCN). Firstly, this paper proves the universal approximation property of RSCN with weighted least squares technique. Secondly, three robust algorithms are presented by employing M-estimation with Huber loss function, M-estimation with interquartile range (IQR) and nonparametric kernel density estimation (NKDE) function respectively to set the penalty weight. Comparison experiments are first carried out based on the UCI standard data sets to verify the effectiveness of these methods, and then the data-driven PS model based on the robust algorithms are established and verified. Experimental results show that the RSCN has an excellent performance for the PS estimation.

Preparation and characterization of Pd modified CeO2 nanoparticles for photocatalytic degradation of dye

The aim of this work was to investigate the structural and optical properties of bare cerium dioxide (CeO2) and Pd-doped CeO2 (0.5, 1.0, 1.5 and 2.0 wt%) photocatalysts prepared by a combination of homogeneous precipitation and the impregnation method. X–ray diffraction analysis indicated that all samples were composed of the cubic fluorite phase of CeO2. Scanning electron micrographs revealed that all samples provided mostly spherical morphology with high agglomeration and estimated particle sizes ranging from 10 to 20 nm in diameter. The XPS core-level spectra of Pd species after incorporating 2.0 wt% Pd–doped CeO2 showed double peaks with binding energies of Pd3d5/2 and Pd3d3/2 corresponding to the Pd2+ oxidation state. The results from diffuse reflectance UV–visible spectroscopy showed that doping with Pd increased the absorbance onset of CeO2 to a longer wavelength, while the band gap decreased from 3.0 eV to 2.8 eV with 2.0% Pd doping concentration. This was likely due to the creation of impurity levels of Pd2+ inside the conduction and valence bands of CeO2. The photoluminescence spectra (PL) indicated that the emission peak intensity of CeO2 decreased in the presence of Pd2+ dopant in CeO2. This was associated with a decrease in the electron–hole recombination rate for electronically-excited. Photocatalytic activity for methyl orange dye degradation under visible light irradiation of 1.0 wt% Pd–doped CeO2 was determined as the optimal doping level with photocatalytic activity 5 times higher than that of bare CeO2 photocatalyst.

Multi-sensor inline measurements of crystal size and shape distributions during high shear wet milling of crystal slurries

Size and shape distributions are among critical quality attributes of particulate products and their inline measurement is crucial for monitoring and control of particle manufacturing processes. This requires advanced tools that can estimate particle size and shape distributions from multi-sensor data captured in situ across various processing steps.In this work, we study changes in size and shape distributions, as well as number of particles during high shear wet milling, which is increasingly being employed for size reduction in crystalline slurries in pharmaceutical processing. Saturated suspensions of benzoic acid, paracetamol and metformin hydrochloride were used in this study. We employ our recently developed tools for estimating particle aspect ratio and particle size distributions from chord length distribution (CLD) measurements and imaging. We also compare estimated particle size distributions from CLD and imaging with corresponding estimates from offline instruments.The results show that these tools are capable of quantitatively capturing changes in particle sizes and shape during wet milling inline. This is the first time that such a capability has been reported in the literature. The ability to quantitatively monitor particle size and shape distributions in real time will enable development of more realistic and accurate population balance models of wet milling and crystallisation, and aid more efficient control of crystallisation processes.

MUD, the next generation in acoustic backscatter sediment measurements

Detection and classification of sediments within rarely occurring turbidity flows is challenging, in part because of the acoustic absorption and scattering within the dense suspended sediments. A new calibrated acoustic backscatter echosounder, the Multifrequency Ultrasonic Device (MUD™), was deployed from 13 to 16, May 2018, at about 120 m water depth within Bute Inlet, Canada. The MUD prototype (1.2 MHz, 769 kHz and 200 kHz) was deployed in a tautline mooring which included a passive acoustic recorder, an ADCP, CT sensor and OBS sensor. The frequencies for the prototype were selected to allow for a compromise between good acoustic range and penetration into dense flows with the potential for particle size discrimination. Preliminary analysis of the data indicates the presence of three turbidity flows over a two-hour period with speeds of up to 2.5 m/s. As anticipated, the lower frequencies did better in penetrating through the dense turbidity flow. This suggests that it will be possible to use inversion of the acoustic backscatter to estimate sediment concentrations within the dense head of the turbidity flow. Multifrequency inversion techniques will be applied to the less dense portion of the flow to estimate particle size distributions. Detection and classification of sediments within rarely occurring turbidity flows is challenging, in part because of the acoustic absorption and scattering within the dense suspended sediments. A new calibrated acoustic backscatter echosounder, the Multifrequency Ultrasonic Device (MUD™), was deployed from 13 to 16, May 2018, at about 120 m water depth within Bute Inlet, Canada. The MUD prototype (1.2 MHz, 769 kHz and 200 kHz) was deployed in a tautline mooring which included a passive acoustic recorder, an ADCP, CT sensor and OBS sensor. The frequencies for the prototype were selected to allow for a compromise between good acoustic range and penetration into dense flows with the potential for particle size discrimination. Preliminary analysis of the data indicates the presence of three turbidity flows over a two-hour period with speeds of up to 2.5 m/s. As anticipated, the lower frequencies did better in penetrating through the dense turbidity flow. This suggests that it will be possible to use inversio...

Role of particle size distribution and magnetic anisotropy on magnetization of antiferromagnetic nanoparticles

Magnetization measurements on antiferromagnetic iron storage protein ferritin are reported. The magnetization as a function of applied magnetic field data in superparamagnetic region are analyzed considering a distribution in particle size. The estimated particle size distribution is compared with that determined from transmission electron micrograph. Effect of magnetic anisotropy on magnetization process of this nanoparticle system is also discussed.

Dispersed particle size characterization by in-line turbidimetry during polymer extrusion

The presence of a dispersed second phase in a medium scatters light, attenuating the transmitted light intensity. This effect is maximized when the average particle size matches the light's wavelength. This work proposes an in-line optical detector which measures the attenuation of the transmitted light intensity by illuminating the medium with different monochromatic light wavelengths. Curves of normalized turbidity as a function of the dispersed particle size were simplified to a Gaussian behavior. We propose a Z parameter, function of the ratio between the transmitted light intensity measured under a particular illuminating color compared to that measured under infrared illumination, which is proportional to the particle size. The method was bench validated employing alumina particles aqueous suspensions with known particle size and during polystyrene melt extrusion traced by alumina particles and polyolefin dispersed second phase. The estimated particle sizes measured in-line during the extrusion, were in good agreement with the reference alumina particles.

Particle size estimation of pulverized fuel in pneumatic pipelines using electrostatic sensing techniques

Particle size measurement of pulverized fuel (PF) provides useful data for efficiency improvement of a pulverizing system, optimization of fuel combustion and emission reduction on a fired power plant. This paper presents an experimental study of particle size estimation of pneumatically conveyed PF through electrostatic sensing. An electrostatic sensor head consisting of two narrow and one wide ring-shaped electrodes is designed and implemented to measure the PF velocity and quantify the features of the sensor signals. Experimental tests using particles with three different size ranges were conducted on the vertical pipe section of a 74 mm bore gas–solid two-phase flow test facility under various flow conditions. Test results show that the root-mean-square magnitude and power spectral density of electrostatic signals vary with particle size. For the same air velocity, the small change in particle velocity is an indication of particle size as the particle velocity decreases when the particle size is larger. The proposed method is capable of estimating PF particle size and has the potential to offer considerable advantages over its counterparts in power plant applications.

A multi-method autonomous assessment of primary productivity and export efficiency in the springtime North Atlantic.

Fixation of organic carbon by phytoplankton is the foundation of nearly all open-ocean ecosystems and a critical part of the global carbon cycle. But quantification and validation of ocean primary productivity at large scale remains a major challenge, due to limited coverage of ship-based measurements and the difficulty of validating diverse measurement techniques. Accurate primary productivity measurements from autonomous platforms would be highly desirable, due to much greater potential coverage. In pursuit of this goal we estimate gross primary productivity over two months in the springtime North Atlantic from an autonomous Lagrangian float using diel cycles of particulate organic carbon derived from optical beam attenuation. We test method precision and accuracy by comparison against entirely independent estimates from a locally parameterized model based on chlorophyll a and light measurements from the same float. During nutrient replete conditions (80% of the study period), we obtain strong relative agreement between the independent methods across an order of magnitude of productivities (r2=0.97), with slight under-estimation by the diel cycles method (-19±5 %). At the end of the diatom bloom, this relative difference increases to -58 % for a six-day period, likely a response to SiO4 limitation, which is not included in the model. In addition, we estimate gross oxygen productivity from O2 diel cycles and find strong correlation with diel cycles-based gross primary productivity over the entire deployment, providing further qualitative support to both methods. Finally, simultaneous estimates of net community productivity, carbon export and particle size suggest that bloom growth is halted by a combination of reduced productivity due to SiO4 limitation and increased export efficiency due to rapid aggregation. After the diatom bloom, high chlorophyll a normalized productivity indicates that low net growth during this period is due to increased heterotrophic respiration and not nutrient limitation. These findings represent a significant advance in the accuracy and completeness of upper ocean carbon cycle measurements from an autonomous platform.

Interferometric particle imaging of ice particles using a multi-view optical system.

Interferometric particle imaging enables particle size estimation in a wide range [from 10μm to a few millimeters] depending on the optical system design. With a multi-view optical system, it is possible to extract more information about the 3D morphology of the particle. In this study, multi-view interferometric out-of-focus imaging of ice particles is performed in a backward-scattering configuration. It is used to estimate ice particle volume and thus to reduce uncertainty concerning particle size estimation. It is further used to better analyze the presence of nearby particles whose images overlap.

Forms of Zinc Occurrence in Blast-Furnace Dust

Results are given for a study of the phase and elemental composition of EVRAZ Nizhny Tagil Metallurgical Plant blast-furnace flue dust. An estimate of particle size is performed in a laser analyzer. Dust is represented by a set of particles of calcined charge with sizes from 1.5 to 1170 μm, with a median size of 82.9 μm. The elemental composition of the blast-furnace dust in local sampling points is determined by x-ray microanalysis. The dust consists of large iron oxide particles and fine particles containing MgO, CaO, SiO2, and Al2O3 in the form of complex silicates and ferrites, as well as inclusions of mechanically entrained coke. Zinc is present in form of oxide, sulphide and sulfate compounds as a surface layer on particles with increased thermal conductivity (FeOx). The zinc and sulfur contents in the layer (1–5 μm) reach 45 and 6%, respectively. The data obtained are useful for substantiating dust treatment processes.

An Iterative Algorithm Based on the Dual Integral Inversion for Particle Sizing

In this paper, an iterative algorithm is proposed to retrieve the particle-size distributions via Fraunhofer diffraction. A dual integral inversion was proposed in our previous work, the inversion is robust and generates precise particle sizing, if the diffraction pattern can be accurately captured. In real applications, the pattern can only be partially detected, and the inversion fails to reconstruct the size distributions in detail. However, the results of the inversion can be used to produce an initial estimate. Then, a simulated diffraction pattern was generated from the estimated particle sizes. The deviation between the measured pattern and the simulated one was deduced to correct the results of particle sizing. The corrections can be achieved in an iterative approach, and the particle-size distribution was updated subsequently. The iteration stopped once the deviation was below the target value. Both simulation and experiment were conducted to validate the feasibility and effectiveness of the proposed algorithm. The results demonstrate that the size distribution from the proposed algorithm agrees well with the original phantoms for both noise-free and noise-contaminated data.

Advantages of mesoporous silica based catalysts in methane reforming by CO2 from kinetic perspective

Nickel confined inside mesoporous silica SBA-15 (Ni5/SBA-15), and iridium supported nickel/SBA-15 catalysts (Ir0.1-Ni5/SBA-15) were tested in dry reforming of methane (DRM). Calcined samples were characterized and their structural and morphological properties were obtained and analyzed by N2-sorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Nickel oxide nanoparticles with estimated particle sizes of 3.3 and 4.2 nm were obtained. Their reducibility and active surface area were determined by temperature programed reduction and temperature programed desorption, respectively. Kinetic studies in DRM were then performed at 480 °C and the facile power-law rate expressions attained for Ni5/SBA-15 and Ir0.1-Ni5/SBA-15 confirmed the dependency of both rates on CO2 and CH4 partial pressures, which decreased the formation of carbon deposition due to the confinement effect of nickel inside support’s mesopores. Activation energies (Ea) of the catalysts were also calculated by varying the temperature. The values of Ea in this study (8.4 and 6 Kcal.mol−1 for CH4 and CO2 on Ni5/SBA-15 catalyst) were lower than those present in other studies, which were mainly performed on non-porous based catalysts. Such outcome stresses on the importance of mesoporous supports in improving the kinetics of DRM. Finally, long tests duration shows that the presence of Ir is beneficial at high temperature (650 °C) in order to maintain the conversion levels of reactants.

Luminescence properties of nanocrystalline Mg2 P2 O7 :Eu phosphor.

Thermoluminescence (TL) measurements were carried out on europium (Eu) doped magnesium pyrophosphate (Mg2 P2 O7 ) nanopowders using gamma irradiation in the dose range of 0.1 to 3kGy. The powder samples were successfully synthesized by chemical co-precipitation synthesis route. The formation and crystallinity of the compound was confirmed by powder X-ray diffraction (PXRD) pattern. The estimated particle size was found to be in nanometer scale by using Debye Scherer's formula. A scanning electron microscopy (SEM) study was carried out for the morphological characteristics of as synthesized Mg2 P2 O7 :Eu phosphor. Photoluminescence (PL) study was carried out to confirm the presence of the rare-earth ion and its valence state. The TL analysis of synthesized samples were performed after the irradiation of Mg2 P2 O7 :Eu with cobalt-60 (60 Co) gamma rays. The high and low intensity peaks of TL glow curve appeared at around 400K, 450K, 500K and 596K respectively. The appreciable shift in peak positions has been observed for different concentrations of Eu ion. The trapping parameters, namely activation energy (E), order of kinetics (b) and frequency factor (s) have been determined using thermal cleaning process, peak shape (Chen's) method and glow curve deconvolution (GCD) functions.