Hyperspectral imaging as an effective tool for prediction the moisture content and textural characteristics of roasted pistachio kernels

The objective of this study was to develop calibration models for prediction of moisture content and textural characteristics (fracture force, hardness, apparent modulus of elasticity and compressive energy) of pistachio kernels roasted in different conditions (temperatures 90, 120 and 150 °C; times 20, 35 and 50 min and air velocities 0.5, 1.5 and 2.5 m/s) using Vis/NIR hyperspectral imaging and multivariate analysis. The effects of different pre-processing methods and spectral treatments such as normalization [multiplicative scatter correction (MSC), standard normal variate transformation (SNV)], smoothing (median filter, Savitzky–Golay and Wavelet) and differentiation (first derivative, D¹ and second derivative, D²) on the obtained data were investigated. The prediction models were developed by partial least square regression (PLSR) and artificial neural network (ANN). The results indicated that ANN models have higher potential to predict moisture content and textural characteristics of roasted pistachio kernels comparing to PLSR models. High correlation was observed between reflectance data and fracture force (R²?=?0.957 and RMSEP?=?3.386) using MSC, Savitzky–Golay and D¹, compressive energy (R²?=?0.907 and RMSEP?=?15.757) using the combination of MSC, Wavelet and D¹, moisture content (R²?=?0.907 and RMSEP?=?0.179) and apparent modulus of elasticity (R²?=?0.921 and RMSEP?=?2.366) employing combination of SNV, Wavelet and D¹, respectively. Moreover, Vis–NIR data correlated well with hardness (R²?=?0.876 and RMSEP?=?5.216) using SNV, Wavelet and D². These results showed the capability of Vis/NIR hyperspectral imaging and the central role of multivariate analysis in developing accurate models for prediction of moisture content and textural properties of roasted pistachio kernels.     

Modeling low-coherence enhanced backscattering using Monte Carlo simulation

Constructive interference between coherent waves traveling time-reversed paths in a random medium gives rise to the enhancement of light scattering observed in directions close to backscattering. This phenomenon is known as enhanced backscattering (EBS). According to diffusion theory, the angular width of an EBS cone is proportional to the ratio of the wavelength of light lambda to the transport mean-free-path length l(s)* of a random medium. In biological media a large l(s)* approximately 0.5-2 mm > lambda results in an extremely small (approximately 0.001 degrees ) angular width of the EBS cone, making the experimental observation of such narrow peaks difficult. Recently, the feasibility of observing EBS under low spatial coherence illumination (spatial coherence length Lsc < l(s)*) was demonstrated. Low spatial coherence behaves as a spatial filter rejecting longer path lengths and thus resulting in an increase of more than 100 times in the angular width of low coherence EBS (LEBS) cones. However, a conventional diffusion approximation-based model of EBS has not been able to explain such a dramatic increase in LEBS width. We present a photon random walk model of LEBS by using Monte Carlo simulation to elucidate the mechanism accounting for the unprecedented broadening of the LEBS peaks. Typically, the exit angles of the scattered photons are not considered in modeling EBS in the diffusion regime. We show that small exit angles are highly sensitive to low-order scattering, which is crucial for accurate modeling of LEBS. Our results show that the predictions of the model are in excellent agreement with the experimental data.     

Oxygen Barrier of Multiwalled Carbon Nanotube/Polymethyl Methacrylate Nanocomposites Prepared by in situ Method

Multiwalled carbon nanotubes (MWCNTs)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by ultrasonic assisted emulsifier free emulsion polymerization technique with variable concentration of functionalized carbon nanotubes. MWCNTs were functionalized with H 2 SO 4 and HNO 3 with continuing sonication and polished by H 2 O 2 . The appearance of Fourier transform infrared absorption bands in the PMMA/MWCNT nanocomposites showed that the functionalized MWCNT interacted chemically with PMMA macromolecules. The surface morphology of functionalized MWCNT and PMMA/MWCNT nanocomposites were studied by scanning electron microscopy. The dispersion of MWCNT in PMMA matrix was evidenced by high resolution transmission electron microscopy. The oxygen permeability of PMMA/MWCNT nanocomposites gradually decreased with increasing MWCNT concentrations.     

Design,fabrication, and testing of a pulper for Kendu (Diospyros melanoxylon Roxb.)

Kendu (Diospyros melanoxylon Roxb.) is a minor forest produce commercially grown in India for its leaves for traditional cigarette‐making. Though the fruit has high nutritive value, it is not used for diet purpose. This may be due to the difficulty in extracting the pulp. To address this issue, a brush type pulping machine was developed for Kendu. The pulper consists of the feed hopper, feed rollers, barrel housing, stainless steel cylinder, and a shaft with two nylon brushes. The feed rollers are provided with conical spikes to compress and shear the hardcover of the fruit. The pulper has an overall dimension of 1.2 m × 0.75 m × 0.40 m and a throughput of 50 kg/hr. The housing field area of the machine is 1.130 m². The overall extraction efficiency of the pulper is 78.36% at an optimized speed and feed rate of 260 rpm and 2.5 kg/min, respectively.

Practical applications

A small‐scale pulper has been designed and fabricated for Kendu fruit, an underutilized minor forest produce. As such, there is no machine to extract pulp from Kendu. Manual removal of hardcover and seeds and separation of the pulp are labor intensive and time consuming. This problem limits the potential use of the fruit. The designed machine will serve as a milling cum pulping machine and would address the issue of underutilization of the fruit. The highly nutritious pulp thus extracted by the pulper can be further processed to various value‐added products. This would certainly increase the commercial use of the fruit and boost income generation to support the livelihood of the people. The designed pulper can also be used for other fruits of similar structure.     

Studies on air permeability of multi-constituent nonwovens

In this work, a series of multi-constituent nonwovens possessing multi-modal fiber diameter distribution was prepared and the air permeability of such nonwoven structures was measured. This approach was extended to bi-constituent nonwovens consisting of fibers with bi-modal diameter distribution and mono-constituent nonwovens composed of fibers with mono-modal diameter distribution. The multi-constituent nonwovens exhibited highest air permeability, followed by the bi- and mono-constituent nonwovens for the same mean fiber diameter. This was explained in terms of the mean pore diameter of the multi-, bi-, and mono-constituent nonwoven structures. An analytical expression of mean fiber diameter of multi-constituent nonwoven structures was derived. The square of the mean fiber diameter in the multi-constituent nonwovens was found to be the harmonic mean of the volume-weighted square of the mean fiber diameter of the individual constituents. The mean fiber diameter coupled with Kozeny–Carman equation was found to predict the air permeability of the multi-, bi-, and mono-constituent nonwovens very well. It was observed that the mono-constituent nonwoven displayed the highest value of Kozeny–Carman coefficient, followed by the bi- and multi-constituent nonwovens.     

Dendrite-Free Aluminum Electrodeposition from AlCl3-1-Ethyl-3-Methyl-Imidazolium Chloride Ionic Liquid Electrolytes

A novel, dendrite-free electrorefining of aluminum scrap alloys (A360) was investigated by using a low-temperature AlCl₃-1-ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte on copper/aluminum cathodes. The bulk electrodeposition of aluminum was carried out at a fixed voltage of 1.5?V, temperatures 323 K to 383 K (50 °C to 110 °C), stirring rate (0 to 120?rpm), concentration (molar ratio AlCl₃:EMIC?=?1.25 to 2.0), and electrode surface modification (modified/unmodified). The study investigated the effect of electrode surface modification, cathode materials, temperature, stirring rate, electrolyte concentration, and deposition time on the deposit morphology of aluminum, cathode current density, and their role in production of dendrite-free aluminum deposit, which is essential for decreasing the production cost. The deposits were characterized using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). It was shown that electrode surface modification, cathode overpotential, and stirring rate play an important role in dendrite-free deposit. Modified electrodes and stirring (60?rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential ( $ \eta_{\text{crt}} \approx - 0.53V $ ) for dendrite formation. Pure aluminum (>99?pct) was deposited for all experiments with a current efficiency of 84 to 99?pct and energy consumption of 4.51 to 5.32?kWh/kg Al.     

Structural and microstructural characterizations of nanocrystalline hydroxyapatite synthesized by mechanical alloying

Single phase nanocrystalline hydroxyapatite (HAp) powder has been synthesized by mechanical alloying the stoichiometric mixture of CaCO₃ and CaHPO₄ powders in open air at room temperature, for the first time, within 2 h of milling. Nanocrystalline hexagonal single crystals are obtained by sintering of 2 h milled sample at 500 °C. Structural and microstructural properties of as-milled and sintered powders are revealed from both the X-ray line profile analysis and transmission electron microscopy. Shape and lattice strain of nanocrystalline HAp particles are found to be anisotropic in nature. Particle size of HAp powder remains almost invariant up to 10 h of milling and there is no significant growth of nanocrystalline HAp particles after sintering at 500 °C for 3 h. Changes in lattice volume and some primary bond lengths of as-milled and sintered are critically measured, which indicate that lattice imperfections introduced into the HAp lattice during ball milling have been reduced partially after sintering the powder at elevated temperatures. We could achieve ~ 96.7% of theoretical density of HAp within 3 h by sintering the pellet of nanocrystalline powder at a lower temperature of 1000 °C. Vickers microhardness (VHN) of the uni-axially pressed (6.86 MPa) pellet of nanocrystalline HAp is 4.5 GPa at 100 gm load which is close to the VHN of bulk HAp sintered at higher temperature. The strain-hardening index (n) of the sintered pellet is found to be > 2, indicating a further increase in microhardness value at higher load.     

Structure, dielectric, ferroelectric, and energy density properties of (1 − x)BZT–xBCT ceramic capacitors for energy storage applications

We investigate the dielectric, ferroelectric, and energy density properties of Pb-free (1 ? x)BZT–xBCT ceramic capacitors at higher sintering temperature (1600 °C). A significant increase in the dielectric constant, with relatively low loss was observed for the investigated {Ba(Zr_0.2Ti_0.8)O₃}_(1?x ){(Ba_0.7Ca_0.3)TiO₃} _x (x = 0.10, 0.15, 0.20) ceramics; however, electric breakdown was low (~140, 170, 134 kV/cm), and of which room temperature (300 K) charging curve energy density values are largest ~0.88, 0.94, and 0.87 J/cm³ with maximum high dielectric constant values ~7800, 8400, and 5200, respectively. Bulk ceramic BZT–BCT materials have shown interesting energy densities with good energy storage efficiency (~72 %) at high sintering temperature; they might be one of the strong candidates for high energy density capacitor applications in an environmentally protective atmosphere.