Characterization of gliadin, secalin and hordein fractions using analytical techniques

Prolamins, alcohol soluble storage proteins of the Triticeae tribe of Gramineae family, are known as gliadin, secalin and hordein in wheat, rye and barley respectively. Prolamins were extracted from fifteen cultivars using DuPont protocol to study their physiochemical, morphological and structural characteristics. SDS-PAGE of prolamins showed well resolved low molecular weight proteins with significant amount of albumin and globulin as cross-contaminant. The β-sheet (32.72–37.41%) and β-turn (30.36–37.91%) were found higher in gliadins, while α-helix (20.32–28.95%) and random coil (9.05–10.28%) in hordeins. The high colloidal stability as depicted by zeta-potential was observed in gliadins (23.5–27.0 mV) followed secalins (11.2–16.6 mV) and hordeins (4.1–7.8 mV). Surface morphology by SEM illustrated the globular particle arrangement in gliadins, sheet like arrangement in secalins and stacked flaky particle arrangement in hordeins fraction. TEM studies showed that secalin and hordein fractions were globular in shape while gliadins in addition to globular structure also possessed rod-shaped particle arrangement. XRD pattern of prolamin fractions showed the ordered crystalline domain at 2θ values of 44.1°, 37.8° and 10.4°. The extracted prolamins fractions showed amorphous as well as crystalline structures as revealed by XRD and TEM analysis. Space saving hexagonal molecular symmetry was also observed in TEM molecular arrangement of prolamins which has profound application in development of plant-based polymers and fibres.

On the micro-PIV accuracy and reliability utilizing non-Gaussian particle images

Optical investigations of the dynamics of concentrated suspensions, such as in blood flows (Fitzgibbon et al. in Biophys J 108(10):2601–2608, 2015. http://doi/org/10.1016/j.bpj.2015.04.013) or slurry flows (Li et al. in Ocean Eng 163(October 2017):691–705, 2018. http://doi/org/10.1016/j.oceaneng.2018.06.046), are challenging due to reduced optical accessibility. Furthermore, the suspension particle image size can strongly deviate from the optimal particle image size for PIV measurements. Optical accessibility can be achieved by refractive index matching of surface labelled suspension particles. This results in particle images that are transparent in the particle image centre, but fluoresce at the particle image rim, resulting in ring-shaped particle images. In the present study, the influence of the particle image size on the cross-correlation result of such ring-shaped particle images is compared with Gaussian and plateau-shaped particle images. Particles of Gaussian image shape result from fully labelled particles with small image diameters and are commonly used in PIV measurements. Such particles are also utilized for the determination of the continuous phase velocities in the experimental part of the present study. With increasing image diameter, fully labelled particles are observed to assume plateau-shaped particle images. Monte Carlo simulations of synthetically generated images show that ring-shaped particle images have a superior behaviour, i.e. they assume a reduced displacement estimation error for noisy as well as for noise-free image data, compared to Gaussian and plateau-shaped particle images. This is also true for large particle image diameters when particle images are intersected at interrogation window borders or when different values of nonzero particle image displacements are considered. The detectability is similar for all three particle image shapes as long as particles do not intersect with the interrogation window border. Interestingly, for intersected particles of large image diameter, ring-shaped particle images show a slightly improved detectability compared to particle images of Gaussian and plateau shape. Furthermore, the detectability is insensitive against a nonzero particle image displacement. The usage of refractive index matched, ring-shaped particle images results in a good optical accessibility of the suspension. This allows to perform simultaneous cross-correlation evaluations on large ring-shaped particle images and fluid tracers with Gaussian particle images that are two orders of magnitude smaller compared to suspension particle images. Velocity measurements are taken on a suspension containing 5 vol% surface labelled, refractive index matched 60 $$\upmu \hbox {m}$$ μ m polymethylmethacrylate (PMMA) particles. Simultaneously, $$\upmu$$ μ PIV measurements of the carrier liquid flow are performed utilizing 1.19 $$\upmu \text {m}$$ μ m fluorescent polystyrene (PS) particles. Measurement results reveal a parabolic shape of the velocity profiles of both phases with a mean slip velocity of 7.4% at the position of maximum streamwise velocity in a 580 $$\upmu \text {m}$$ μ m high trapezoidal channel. An error analysis confirms the presence of these slip velocities within a 68.5% confidence interval. A measurement uncertainty in the order of magnitude of $${\mathcal {O}}(10^{-1}\ \mathrm{px})$$ O ( 10 - 1 px ) is reached for both fluid tracers and suspension particles. Overall, the present study demonstrates theoretically and experimentally that the usage of suspension particles with ring-shaped images is superior compared to Gaussian and plateau-shaped particle images of the same size. Additionally, the present study demonstrates that the usage of ring-shaped particle images allows to investigate suspension bulk dynamics by measuring velocity fields of both the suspended and the continuous phase simultaneously and with an overall uncertainty that is in the same order of magnitude as for standard $$\upmu$$ μ PIV measurements. Graphic abstract

In situ formation of zinc oxide on bamboo bleached pulp in preparation of antibacterial paper: Effect of precursors addition

An approach of green in situ synthesis single-step method was applied to produce antibacterial paper. The objective was to investigate the effect of precursor addition on the formation of zinc oxide particles using an in situ single-step method. Zinc chloride concentrations of 0.1, 0.3, 0.5, and 0.7 M were prepared and added into a solution of algae extract and bamboo pulp. The prepared pulps were tested and made into handsheets using a papermaking machine based on TAPPI T205 (2006). Morphological observation of treated papers was conducted using a field emission scanning electron microscope (FESEM). An average of 400 to 570 nm zinc oxide spherical-shaped particle was observed on the fibers of paper. The percentage of element composition of the treated paper were 15.08% to 34.08% of zinc and 17.45% to 32.59% of oxygen captured via scanning electron microscopy with energy dispersive X-ray (SEM-EDX) analysis. The crystallinity test was performed using X-ray dispersion (XRD). A higher percentage of precursors exhibited a more amorphous structure. A measurement of more than 30% increment of inhibition zone was obtained from 10.00 to 25.00 mm against S. aureus, S. choleraesuis, and E. coli. Precursors addition of more than 0.3 M would have the most potential to enhance the growth of zinc oxide via in situ preparation, hence providing better antibacterial properties of the prepared papers.

Application of the Folgar–Tucker model to predict the orientation of particles of different aspect ratios in polymer suspensions

The increasing requirements on plastic parts demand a rising use of combined functional and reinforcing materials. Therefore, often reinforcing particles with different aspect ratios are added to the plastic as additive mixtures. However, the engineering design process of reinforced parts requires an early knowledge of the expected orientation of the reinforcing particles. Numerous models try to predict the orientation of particles in polymer suspensions. However, the interaction coefficient strongly depends on the aspect ratio of the particles and a prediction of the orientation behavior of additive mixtures with differently shaped particles has not been validated using conventional methods. In this work, the orientation of differently shaped particle mixtures in polymer suspensions is investigated for different fluid channel geometries. Finally, the Folgar–Tucker model is applied to filler mixtures and implemented into OpenFOAM®, which enables the comparison of filler orientation in different fluid channel geometries. Regarding the experiments a characteristic increase of the interaction coefficient was observed at a filling level of 5%. Furthermore, it was shown that a balanced mixing ratio yields higher interaction coefficients. With regard to the performed simulations, it was possible to show qualitatively how a considered interaction between fibers and platelets affects the orientations.

The Effect of Temperature Synthesis on the Plate-Like Particle of Bi4Ti3O12 Obtained by Single Molten NaCl Salt

Three-layer Aurivillius compound bismuth titanate (Bi4Ti3O12) is well known for having interesting properties such as ferroelectric and photocatalyst. Many researchers reported that the unique plate-like shaped particle affecting ferroelectric and photocatalyst properties. The molten salt synthesis is the common simple method to obtain that unique morphology. In this research, Bi4Ti3O12 was synthesized using single molten salt NaCl at various temperatures, which is 800, 850, 900, and 950 oC. X-Ray Diffraction data showed that all obtained Bi4Ti3O12 have a B2cb space group with no impurities detected. The Raman spectra shows the characteristic vibration modes of Bi4Ti3O12 at 62, 117, 228, 269, 332, 364, 536, 851 cm-1. The plate-like shaped particle was confirmed by SEM analysis. Based on SEM images, the size of the particle increased along with the synthesis temperature, which is due to the thermal effect on grain growth.

Experiment and Simulation of Erosion Mechanism and Deformation Characteristics in Al6061-T6 beam due to Rhomboid Particle Impacts

The erosion mechanism and deformation characteristics of rhomboid-shaped particle impacting metal beam are studied. Physical experiments of rhomboid-shaped particle impacting cantilever beam and fixed-fixed beam are carried out respectively. The erosion behavior of particles and deformation characteristics of beam are captured by high-speed imaging system. Meanwhile, the numerical models of rhomboid-shaped particle impacting beam, based on FEM-SPH coupled method, are established. The effects of the geometrical parameters of the beam, the incident conditions of particle and the impact position on the elastic-plastic deformation of beam and rebound behavior of particles are further analyzed. The results show: (1) The width of cantilever beam affects its maximum deflection and deformation; (2) The threshold value of breakdown velocity is controlled by the substrate size; (3) The increment of internal energy is basically independent of the impact position; (4) The deflection value at impact position of beam is maximized under the critical impact condition.

Model-based closure experiments with optical particle counters for dust-like aerosols

<div> <div></div> </div><div><!-- COMO-HTML-CONTENT-START --> <p>The size distribution of desert dust is a central parameter, e.g., for the dust climate effect and the fertilization of oceans and rain forests. The uncertainties of size distribution measurements, however, are large for which the nonsphericity of dust particles is a major reason. Optical particle counters (OPCs) are frequently used for size distribution measurements and possible reasons for uncertainties include (a) the fact that nonspherical dust particles fly with individual orientations through the sampling volume of the OPC while the scattering signals and derived sizes depend on particle orientation, (b) the variability of particle shape, and (c) uncertainties about which definition of particle size is best suited for nonspherical dust.</p> <p>To test the consistency between OPC measurements and independent measurements with other instruments types (e.g., a nephelometer or a lidar) closure experiments can be performed. In such experiments, size distributions derived from OPC measurements are used as input for model calculations of specific optical parameters which then are compared to independent measurements of the same optical parameters (e.g. scattering or backscattering coefficient) of the same aerosol. Deviations have been reported in the literature for desert dust. These deviations may be caused by the particle nonsphericity affecting the derivation of size distributions from OPC as indicated above but may also have other causes, e.g., using a wrong refractive index or assuming spherical particles for calculating the specific optical parameters. So far, the OPC nonsphericity effect has not been investigated in detail. A better understanding of this effect would be helpful for our understanding of size distribution uncertainties and of reasons for deviations in closure experiments.</p> <p>In order to gain insight into the OPC nonsphericity effect, we performed simulations for different combinations of OPCs and instruments measuring specific optical parameters. Irregular dust-like shapes over a wide size range and different refractive indices were considered. Firstly, the deviations of the derived sizes from the original particle sizes were analyzed. Secondly, the derived sizes were used for Mie simulations of the optical parameters and the deviations from those of the original irregularly-shaped particle were calculated. In this respect, e.g., nephelometer responses and lidar-relevant parameters were simulated to reproduce possible closure experiments. These results will be compared to measurement-based closure experiments performed during field campaigns or in a laboratory in order to investigate how well the OPC nonsphericity effect explains observed discrepancies.</p> <p>The simulated closure experiments show, for example, an overestimation of the scattering coefficient at λ=532nm by about 5% to 34% (depending on size range) when using size distributions derived from the DMT CAS instrument (λ=658nm, 4°-12° scattering angle) assuming non-absorbing dust particles. Using the TSI OPS model 3330 (λ=660nm, 30°-150° scattering angle) deviations in the range from -16% to +16% are found.</p> </div>

A kinematics-based model for the settling of gravity-driven arbitrary-shaped particles on a surface

A discrete model is proposed for settling of an arbitrary-shaped particle onto a flat surface under the gravitational field. In this method, the particle dynamics is calculated such that (a) the particle does not create an overlap with the wall and (b) reaches a realistic equilibrium state, which are not guaranteed in the conventional discrete element methods that add a repulsive force (torque) based on the amount of overlap between the particle and the wall. Instead, upon the detection of collision, the particle’s kinematics is modified depending on the type of contact, i.e., point, line, and surface types, by assuming the contact point/line as the instantaneous center/line of rotation for calculating the rigid body dynamics. Two different stability conditions are implemented by comparing the location of the projection of the center of mass on the wall along gravity direction against the contact points to identify the equilibrium (stable) state on the wall for particles with multiple contact points. A variety of simulations are presented, including smooth surface particles (ellipsoids), regular particles with sharp edges (cylinders and pyramids) and irregular-shaped particles, to show that the method can provide the analytically-known equilibrium state.