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Although carbon nanotubes possess unique characteristics to be used for separation purposes, one of the most challenging problems affecting the preparation of carbon nanotubes-incorporated-mixed matrix membranes has been ascribed to Van der Waals interactions among carbon nanotubes walls, which hinder the pristine nanotubes' ability to make good interfacial interactions within the polymer matrix. To overcome this challenge, herein, poly (styrene sulfonic acid)-grafted- multi-walled carbon nanotubes were prepared via in-situ radical polymerisation and then incorporated into poly (vinyl alcohol), resulting in enhanced pervaporation performance of poly (vinyl alcohol) membranes. The observed results indicated that poly (styrene sulfonic acid)-modified carbon nanotubes could effectively vanquish the Van der Waals forces between nanotube walls. In general, our experiments revealed that the attachment of a bulky polymer containing hydrophilic sulfonic groups could improve the pervaporation performance of a poly (vinyl alcohol) membrane. [ABSTRACT FROM AUTHOR]

Optical remote sensing of earth surface processes commonly relies on the red, green, blue (RGB), near-infrared (NIR) and shortwave-infrared (SWIR) electromagnetic bands. Most of the optical sensors mounted on unmanned aerial vehicles and satellites provide the RGB and NIR bands, but only a few offer SWIR output. The Red-NIR reflectance space has been widely applied for remote sensing of various land surface variables including soil moisture. The linear relationship between the Red-NIR reflectance of bare soil is established as the base and then moisture isolines are assumed perpendicular to the soil line. In this study, we show that this assumption is not consistent with the actual Red-NIR space geometry, which in many cases introduces soil moisture estimation errors. To overcome this limitation, we propose a new mathematical transformation to the original Red-NIR space followed by newly defined soil moisture isolines that are more consistent with the actual observations. This new Transformed Red-NIR (TRN) model is compared with the Conventional Red-NIR (CRN) model using data from a sugarcane field located in southwestern Iran. Twelve Land Remote-Sensing Satellite (Landsat)-8 images were acquired during the sugarcane growth season. For validation of the remotely sensed data, ground reference soil moisture was determined at 22 locations at five different depths via core sampling and oven-drying. Our results indicate that the TRN model significantly improves the accuracy of remotely sensed soil moisture. [ABSTRACT FROM AUTHOR]

A phenomenological computational fluid dynamics model was developed to simulate drying process of a porous body using electric field corona discharge. The set of coupled nonlinear partial differential equations were solved simultaneously and compared with the experimental findings in the literature. The relative error of the corona wind velocity compared to the experiments was less than 1%. The main gradients of the EHD volume force and corona wind were close to the discharge electrode. Moreover, for no inlet air, the corona wind velocity and field distribution indicated the existence of vortices as the main factor for enhancing mass transfer during the drying process. At a constant air velocity, increase in the voltage caused increasing the corona velocity. In addition, by increasing the air velocity to some extent, the corona velocity first increased and then started to drop. As a result, for any voltage and electrode distance from the surface, an optimum air velocity could be determined. Due to the sweep impact of the primary air flow and moving the ionized molecules to the outside, the drying rates at air velocity of 1 m s−1 were higher than those for air velocity of 1.5 m s−1. Applying an intake air flow also altered the optimal electrode velocity from the surface due to the occurred change in the corona discharge. Therefore, is concluded that the severity of mass humidity changes is affected by the applied voltage, electrode distances from the surface, temperature, and the intake air velocity. [ABSTRACT FROM AUTHOR]

Polymer/nanoparticle mixed matrix membranes (MMMs) is one of the most important topics in gas separation field. In this study, to improve gas separation efficiency, methoxy poly(ethylene glycol) methacrylate (MPEG) was grafted on TiO2 surface and was used for synthesis of poly (methyl methacrylate) (PMMA) MMMs. Gas permeation and separation properties of PMMA/PMPEG-TiO2 MMMs were studied for CO2, CH4, O2, and N2 gases. The results showed that the MMM filled with 5 wt% PMPEG-TiO2 nanoparticle exhibited optimal separation performance with CO2 permeability of 32.48 Barrer and CO2/N2 selectivity of 56.98, which are higher than pure polymer (2.75 Barrer and 36.71). [ABSTRACT FROM AUTHOR]

During rough rice drying, gradients of moisture content and glass transition temperature cause thermal and mechanical stresses inside the kernel. These stresses eventuate to kernel fissuring during the milling process. In this study, convective drying of Hashemi (long grain) rough rice was applied to investigate the effect of continuous and stepwise changes in air temperature on stress cracking index and process duration. Toward this objective, the concepts of glass transition and analysis of moisture contents distributions within the rice kernel were determined through a numerical modeling of mass transfer. For stepwise temperature change, the drying experiments were conducted at temperatures above the glass transition temperature. Results indicated that the stress cracking index under stepwise temperature change conditions (i.e., within the rubbery state) was reduced compared to the continuous mode probably due to a drip in the moisture content gradients created inside the kernels during the drying process. Moreover, the drying duration significantly was shortened when the kernel was dried within the rubbery state due to faster diffusion moisture within the kernel. [ABSTRACT FROM AUTHOR]

In this study, multi-stage intermittent drying (MSID) of rough rice is considered based on stress cracking index (SCI), tempering index (TI), and total drying/tempering duration for Hashemi and Koohsar varieties experimentally and theoretically. The samples were dried at 60°C for 20, 40, and 60 min and tempered at 60°C for 40, 80, 120, 160, 200, and 240 min after each drying stage. Afterward, the completion of the tempering process was assessed using the TI along with analysis of moisture content kinetics by a simplified drying model. For both varieties, the SCI decreased significantly until continuing the tempering operation to certain durations and increased for longer drying durations in each drying stage. Considering the SCI and the total drying/tempering duration, the tempering durations of 200 and 160 min after 40 min drying in each stage were determined as the best performed conditions for MSID of Hashemi and Koohsar varieties, respectively. The results achieved by the TI were in conformity with those obtained by the mathematical model. It was concluded that the TI and simulation of surface moisture content on a kernel could be applied for estimating the time required for supplementation of the tempering process to eliminate moisture content gradients created inside the kernels during the drying process. [ABSTRACT FROM PUBLISHER]

Solar drying technology is a noteworthy technique as it uses the renewable solar energy. In this study, thin slices of banana were dried by using an indirect forced solar dryer at air mass flow rates of 0.016, 0.041, and 0.082 kg s−1. In order to assess the kinetics of shrinkage and color changes, image processing technique was applied for determining area, volume, density, total color difference and browning index. Shrinkage factor of the samples was less than 1 during drying indicating non-isotropic shrinkage with contraction of inner voids. Furthermore, product shrinkage showed two descending drying steps in which the volume change was more than the evaporated water volume in the first step and equal to that in the second step. The dimensionless evaporated water volume with respect to the dimensionless volume difference of the product also revealed that two steps of volume change existed during drying separated at critical moisture ratio 0.23. The area and volume changes were only related to the product moisture content and were independent of the air mass flow rate, and hence air temperature. In contrary to the browning index, the total color difference was not influenced by air mass flow rate and the least change in browning index occurred at mass flow rate of 0.041 kg s−1. [ABSTRACT FROM AUTHOR]

The selection of calibration method is one of the most important factors affecting the measurement accuracy with near infrared spectroscopy. In this research, the performance of two general calibration methods, namely, linear partial least squares regression and nonlinear back propagation artificial neural networks for firmness predicting of ‘Mazafati’ date fruit was investigated. A total of 175 date samples harvested during fruit ripening were selected as the data set. Optical scanning was performed with a fiber optic near infrared spectrometer with a range of 900–1700 nm. The inputs of back propagation artificial neural networks were the first five principal components resulting from the principal component analysis, namely, principal component analysis artificial neural network modeling or the first six latent variables obtained from partial least squares regression, namely, latent variable artificial neural network modeling. Both the leave-one-out cross validation and test set validation showed the priority of latent variable artificial neural network model with respect to partial least squares and also principal component analysis artificial neural network models. The best latent variable artificial neural network model could predict the firmness of Mazafati date fruits with Rp2of 0.90, RMSEP of 1.30 N, and SDRpof 3.28. The results also recommended the adoption of nonlinear latent variable artificial neural network modeling for applying light scattering properties of fruits in order to predict indirect property of firmness with near infrared spectroscopy. [ABSTRACT FROM AUTHOR]

The sorption behaviors of sulfuric, perchloric, and phosphoric acids in polybenzimidazole membranes have been investigated. The results of sorption isotherms are consistent with the general form of a dual-mode sorption isotherm. The dual-mode sorption parameters were found using a least-squares program by fitting experimental data to a dual-mode equation. Results indicate a correlation between permeant properties like acidity, size, and the affinity constant in Langmuir-mode sorption species. Moreover, the results show that the size of the permeants has the dominant effect on Henry's constant. The obtained results for [image omitted], site saturation constant, in Langmuir-mode sorption in the case of perchloric and phosphoric acids, reveals that the two acid molecules interact with two N-H basic groups in the polybenzimidazole repeat units. But in the case of sulfuric acid, it is shown that sulfuric acid neutralizes some of the basic groups in the polymer by its strong second hydrogen and the obtained value for [image omitted] was 1.25. [ABSTRACT FROM AUTHOR]