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"Size determination"
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Tiny and the big dig
Tiny is a small, but very determined dog and right now he smells a big bone buried deep in the earth of the garden--and he is going to get that bone no matter how far down he has to dig.
Book
BATCHED BANDIT PROBLEMS
Motivated by practical applications, chiefly clinical trials, we study the regret achievable for stochastic bandits under the constraint that the employed policy must split trials into a small number of batches. We propose a simple policy, and show that a very small number of batches gives close to minimax optimal regret bounds. As a byproduct, we derive optimal policies with low switching cost for stochastic bandits.
Journal Article
Scherrer formula: estimation of error in determining small nanoparticle size
The lower limit of the applicability of the Scherrer formula has been established by calculating the diffraction patterns from model nanoparticles by the Debye formula. Particle size was calculated using the Scherrer formula for different hkl-peaks. The obtained data of particle sizes were compared with \"real\" sizes of model particles in the same hkl-directions. The form-factor Khkl was analyzed as main correction of Scherrer formula. It was shown that the Scherrer formula error increases nonlinearly at particle sizes less than 4 nm. For any hkl direction, the absolute error of average particle size determination using formula does not exceed 0.3 nm. Analysis shows that average particle size can be determined by Scherrer formula from single diffraction peak of experimental pattern for center-symmetrical particles.
Journal Article
The effect of natural fiber ratio on mechanical properties of kaolin/fly–ash at low temperature ceramics
This study aims to increase the feasibility of ceramics at low temperature using natural fibers. The ceramics (Ce) were prepared by mixing a powder of kaolin and fly–ash at an equal ratio of 50:50 wt.%. The mixture was milled by ball–milling technique. The natural fibers ceramics (CeNF) were created by adding local pineapple leaves to kaolin and fly–ash powder. Scanning electron microscopy (SEM) was used to amorphous observation and particle size determination. The compositions of Ce and CeNF were investigated by using X–ray diffraction (XRD) technique. The mechanical properties of ceramics were determined by hardness and density test. The results showed that the grinding of kaolin and fly–ash for 4 h produced the highest strength Ce. For the addition of local pineapple leaves at 2 wt.%, the strength could be increased from 92.9 kgf to 118.3 kgf.
Journal Article
Recent developments in mass spectrometry for the characterization of micro- and nanoscale plastic debris in the environment
Development of analytical methods for the characterization (particle size determination, identification, and quantification) of the micro- and nanoscale plastic debris in the environment is a quickly emerging field and has gained considerable attention, not only within the scientific community, but also on the part of policy makers and the general public. In this Trends paper, the importance of developing and further improving analytical methodologies for the detection and characterization of sub-20-μm-range microplastics and especially nanoplastics is highlighted. A short overview of analytical methodologies showing considerable promise for the detection and characterization of such micro- and nanoscale plastic debris is provided, with emphasis on recent developments in mass spectrometry (MS)–based analytical methods. Novel hyphenated techniques combining the strengths of different analytical methods, such as field flow fractionation and MS-based detection, may be a way to adequately address the smallest fractions in plastic debris analysis, making such approaches worthwhile to be further explored.
Journal Article
Particle Recognition on Transmission Electron Microscopy Images Using Computer Vision and Deep Learning for Catalytic Applications
Recognition and measuring particles on microscopy images is an important part of many scientific studies, including catalytic investigations. In this paper, we present the results of the application of deep learning to the automated recognition of nanoparticles deposited on porous supports (heterogeneous catalysts) on images obtained by transmission electron microscopy (TEM). The Cascade Mask-RCNN neural network was used. During the training, two types of objects were labeled on raw TEM images of ‘real’ catalysts: visible particles and overlapping particle projections. The trained neural network recognized nanoparticles in the test dataset with 0.71 precision and 0.72 recall for both classes of objects and 0.84 precision and 0.79 recall for visible particles. The developed model is integrated into the open-access web service ‘ParticlesNN’, which can be used by any researcher in the world. Instead of hours, TEM data processing per one image analysis is reduced to a maximum of a couple of minutes and the divergence of mean particle size determination is approximately 2% compared to manual analysis. The proposed tool encourages accelerating catalytic research and improving the objectivity and accuracy of analysis.
Journal Article
Impact of varying analytical methodologies on grain particle size determination
The determination of particle size is an important quality control measurement for feed manufacturers, nutritionists, and producers. The current approved method for determining the geometric mean diameter by weight (d^sub gw^) and geometric standard deviation (S^sub gw^) of grains is standard ANSI/ASAE S319.4. This method controls many variables, including the suggested quantity of initial material and the type, number, and size of sieves. However, the method allows for variations in sieving time, sieve agitators, and the use of a dispersion agent. The objective of this experiment was to determine which method of particle size analysis best estimated the particle size of various cereal grain types. Eighteen samples of either corn, sorghum, or wheat were ground and analyzed using different variations of the approved method. Treatments were arranged in a 5 x 3 factorial arrangement with 5 sieving methods: 1) 10-min sieving time with sieve agitators and no dispersion agent, 2) 10-min sieving time with sieve agitators and dispersion agent, 3) 15-min sieving time with no sieve agitators or dispersion agent, 4) 15-min sieving time with sieve agitators and no dispersion agent, and 5) 15-min sieving time with sieve agitators and dispersion agent conducted in 3 grain types (ground corn, sorghum, and wheat) with 4 replicates per treatment. The analytical method that resulted in the lowest d^sub gw^ and greatest S^sub gw^ was considered desirable because it was presumably representative of increased movement of particles to their appropriate sieve. Analytical method affected d^sub gw^ and S^sub gw^ (P ≤ 0.05) measured by both standards. Inclusion of sieve agitators and dispersion agent in the sieve stack resulted in the lowest d^sub gw^, regardless of sieving time. Inclusion of dispersion agent reduced d^sub gw^ (P ≤ 0.05) by 32 and 36 μm when shaken for 10 and 15 min, respectively, compared to the same sample analyzed without dispersion agent. The addition of the dispersion agent also increased Sgw. The dispersion agent increased the quantity of very fine particles collected in the pan; therefore, Sgw was significantly greater (P ≤ 0.05). Corn and sorghum ground using the same mill parameters had similar dgw (P > 0.05), but wheat ground using the same mill parameters was 120 to 104 μm larger (P ≤ 0.05) than corn and sorghum, respectively. Both sieve agitators and dispersion agent should be included when conducting particle size analysis. The results indicate that 10 and 15 min of sieving time produced similar results.
Journal Article
Advanced Particle Size Analysis in High-Solid-Content Polymer Dispersions Using Photon Density Wave Spectroscopy
High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12–55% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (Χ2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques.
Journal Article
Silanized modified cellulose: preparation and evaluation of O/W Pickering emulsion stabilizers
Cellulose nanofibrils (CNFs) are ideal Pickering emulsion stabilizers, but they have limitations due to their strong hydrophilicity. In this work, modified CNFs (M-CNFs) with a water contact angle of 93.1 ± 0.6° were successfully prepared by methyl trimethoxysilane. Subsequently, the performance of the M-CNFs was characterized by crystallization performance determination (XRD), Fourier transform infrared spectra (FTIR), particle size determination, thermogravimetric analysis and so on. As well as, the O/W Pickering emulsions prepared with M-CNFs as a stabilizer has good performance in the diameter and particle size distribution, most droplet sizes can be maintained within 5 μm, and unimodal distribution was presented. It can show more stable performance under medium and alkaline conditions (pH = 7–11), and has certain anti-ion ability. Thus, this study has potential applications in coating, paint, sewage treatment and other fields.
Journal Article
Study of micelles and surface properties of triterpene saponins with improved isolation method from Hedera helix
Triterpene saponin fractions were extracted from
Hedera helix
, and in-depth analysis of their physicochemical properties was conducted. Hederasaponin B and hederacoside C were extracted from
Hedera helix
leaves, and their purification was carried out using reverse phase column chromatography with a modified method, providing an affordable alternative to HPLC. Structurally, hederacoside C differs from hederasaponin B only by the presence of a hydroxyl group at the carbon 23 of the aglycon. The critical micelle concentration (cmc) measurement confirmed hydrophilic nature of hederacoside C that led to a higher cmc value compared to hederasaponin B and alpha-hederin. Therefore, the cmc value of hederasaponin B is nearly an order of magnitude lower compared to hederacoside C. Additionally, the study of the surface tension revealed that the more lipophilic alpha-hederin displayed a greater surface tension value (γ
cmc
= 39.8 mN·m
−1
) compared to hederasaponin B and hederacoside C. Measurements of the surface tension dependence on the concentration in water were enabled to determine the area corresponding to a single saponin molecule at the water/air phase interface (A
cmc
). Notably, structural changes had negligible effects, as Acmc values remained practically identical. Particle size determination further indicated that hederacoside C forms only micelles compared to the remaining substances that showed signs of vesicles formation. Alpha-hederin, as the only measured molecule capable of ionization, showed a negative zeta potential.
Journal Article