Sensory Quality Evaluation of Rice Using Visible and Shortwave Near-Infrared Spectroscopy

This research aimed to develop both visible and shortwave near-infrared spectroscopy to evaluate the sensory qualities of cooked rice. In this study, four different types of milled rice were used: parboiled, white, new Jasmine, and aged Jasmine. The sensory qualities of cooked rice (adhesiveness, hardness, stickiness, dryness, whiteness, and aroma) were evaluated by a trained sensory panel. The results demonstrated that these sensory attributes correlated with visible and shortwave near-infrared spectral data. Both visible and shortwave near-infrared spectroscopy models used for predicting the sensory qualities of cooked rice were established using partial least squares regression. All prediction results for sensory qualities showed a range of R²_val between 0.837 and 0.918, with the highest found for aroma (0.918). The proposed models can be utilized in quality control by the rice industry.     

Doping GaP Core–Shell Nanowire pn‐Junctions: A Study by Off‐Axis Electron Holography

The doping process in GaP core–shell nanowire pn‐junctions using different precursors is evaluated by mapping the nanowires' electrostatic potential distribution by means of off‐axis electron holography. Three precursors, triethyltin (TESn), ditertiarybutylselenide, and silane are investigated for n‐type doping of nanowire shells; among them, TESn is shown to be the most efficient precursor. Off‐axis electron holography reveals higher electrostatic potentials in the regions of nanowire cores grown by the vapor–liquid–solid (VLS) mechanism (axial growth) than the regions grown parasitically by the vapor–solid (VS) mechanism (radial growth), attributed to different incorporation efficiency between VLS and VS of unintentional p‐type carbon doping originating from the trimethylgallium precursor. This study shows that off‐axis electron holography of doped nanowires is unique in terms of the ability to map the electrostatic potential and thereby the active dopant distribution with high spatial resolution.     

Non-linear viscoelastic behavior of cooked white,brown, and germinated brown Thai jasmine rice by large deformation relaxation test

Stress relaxation tests at high strain were conducted on scoops of cooked white, brown, and germinated brown Thai jasmine rice using a King Mongkut’s Institute of Technology Ladkrabang test rig. The diameter of the scoop was 35 mm and the height was 10 mm. Non-linear modeling, consisting of four relaxation models, was applied to the data obtained for each type of rice. The modeling methods included Peleg and Normand’s; Yadav, Roopa, and Bhattacharya’s; Jaya and Durance’s; and Myhan, Markowski, and Daszkiewicz’s. The cooked white rice showed greater tenderness compared to the others. The toughness of the three types of cooked rice was not found to be different. The Myhan et al. model was the most accurate in describing the non-linear viscoelastic behavior of all types of cooked rice. The cooked brown rice showed the highest initial decay rate, but the lowest relaxation, lowest elasticity, and greatest viscosity. In contrast, the cooked white rice had opposite characteristics.     

Transient prolongation of ventricular action potential duration after metabolic inhibition

Transient prolongation of the action potential duration was observed in canine ventricular muscle during the reoxygenation period following metabolic inhibition. We investigated the effects of verapamil, lanthanum (La3+), and hexamethyleneamiloride (HMA) on the recovery time course of the action potential and its rebound prolongation. The time course of the intracellular resistivity was estimated from the conduction velocity and electrograms. The action potentials of canine left ventricular trabeculae were recorded by the conventional microelectrode technique. After a control tracing was obtained, the preparation was perfused with a hypoxic, acidic solution for 20 min and then reoxygenated with regular Tyrode's solution. After reoxygenation, action potential prolongation exceeding the control value by 21.0 +/- 7.3% was observed depending on the degree of metabolic inhibition. Verapamil depressed the rebound prolongation when it was added before the start of metabolic inhibition, but not when added after reoxygenation was started. La3+ and HMA depressed the rebound phenomenon. Intracellular resistivity was increased during metabolic inhibition, but showed no significant changes during the period of action potential prolongation. It was concluded that the rebound action potential prolongation was related to the accumulation of intracellular Ca2+ during metabolic inhibition. Other ions, such as Na+ and H+ may also contribute to the phenomenon by modulating outward currents.     

Rheological study of EPDM/silicone rubber blends phase inversion and characterization of resultant mechanical and thermal properties

This study was committed to the characterization of the rheological, thermal, mechanical, and morphological properties of ethylene-propylene-diene monomer (EPDM)/silicone rubber (SR) blends. These blends are a potential new class of materials for the insulation of circuits and electrical components that actuate in environments with high heat generation. The blends were produced in a torque rheometer with a Banbury type rotor, varying the concentration of EPDM and SR. Results obtained by capillary rheometry were applied to three theoretical models to analyze the phase inversion threshold, which was confirmed by scanning electron microscopy images. Such analyzes were important to describe the consequence of phase inversion on the evaluated properties. It was reported that the increase in SR concentration decreased the elastic modulus and increased the tensile strength of the blends. For blends with composition situated after phase inversion, the SR becomes the matrix, leading to a significant rise in the Vicat softening temperature and reduced thermal conductivity. Such improvements extend the range of applications of these materials as electrical insulators in environments with higher heat generation.     

Mechanical properties and flammability of sisal/PP composites: Effect of flame retardant type and content

In this research, magnesium hydroxide (Mg(OH)₂) and zinc borate, as flame retardants, were incorporated into sisal/PP composites. Maleic anhydride grafted polypropylene was also used as a compatibilizer. Adding flame retardants into sisal/PP composites reduced burning rate and increased thermal stability of the composites. No synergistic effect was observed when both magnesium hydroxide and zinc borate were incorporated in the sisal/PP composites. In addition, the sisal/PP composites exhibited insignificant difference of shear viscosity at high shear rate indicating that types of flame retardants used in this study had no impact on the processability of the composites. Good distribution of flame retardants and sisal fiber in PP matrix was also observed. All PP composites had lower impact strength than the neat PP. However, the sisal/PP composites with the addition of Mg(OH)₂ and zinc borate exhibited comparable tensile and flexural properties to the sisal/PP composites without adding those flame retardants. Therefore, the addition of Mg(OH)₂ and zinc borate enhanced flame retardancy of sisal/PP composites without sacrificing their mechanical properties.     

Major gaseous and PAH emissions from a fluidized-bed combustor firing rice husk with high combustion efficiency

This experimental work investigated major gaseous (CO and NO_x) and PAH emissions from a 400 kW_th fluidized-bed combustor with a cone-shaped bed (referred to as ‘conical FBC’) firing rice husk with high, over 99%, combustion efficiency. Experimental tests were carried out at the fuel feed rate of 80 kg/h for different values of excess air (EA). As revealed by the experimental results, EA had substantial effects on the axial CO and NO_x concentration profiles and corresponding emissions from the combustor. The concentration (mg/kg-ash) and specific emission (μg/kW h) of twelve polycyclic aromatic hydrocarbons (PAHs), acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene and indeno[1,2,3-cd]pyrene, were quantified in this work for different size fractions of ash emitted from the conical FBC firing rice husk at EA = 20.9%. The total PAHs emission was found to be predominant for the coarsest ash particles, due to the effects of a highly developed internal surface in a particle volume. The highest emission was shown by acenaphthylene, 4.1 μg/kW h, when the total yield of PAHs via fly ash was about 10 μg/kW h.     

Nondestructive estimation of maturity and textural properties on tomato ‘Momotaro’ by near infrared spectroscopy

Near infrared spectroscopy offers the possibility to classify and predict the internal quality of fruits and vegetables. The objective of this study was to evaluate the ability of near infrared spectroscopy to classify the maturity level and to predict textural properties of tomatoes variety “Momotaro”. Principal component analysis (PCA) and Soft independent modeling of class analogy (SIMCA) were used to distinguish among different maturities (mature green, pink and red). Partial least squares (PLS) regression was used to estimate textural properties, alcohol insoluble solids and soluble solids content of the tomatoes. The PCA calibration model with mean normalization pretreatment spectra of mature green tomatoes, gave the highest distinguishability (96.85%). It could classify 100.00% of red and pink tomatoes. The SIMCA model could not give better accuracy in maturity classification than individual PCA models. Among the textural parameters measured, the bioyield force from the puncture test with the near infrared (NIR) spectra (between 1100 and 1800 nm) pretreated by multiplicative scatter correction (MSC) had the highest correlation coefficient between NIR predicted and reference values (r = 0.95) and lowest standard error of prediction (SEP = 0.35 N) and bias of 0.19 N. The ratio of standard deviation of reference data of prediction set to standard error of prediction (RPD) was 2.71. In the case of Momotaro tomato, NIR spectroscopy by using PLS regression could not predict alcohol insoluble solids in fresh weight accurately but could predict soluble solids content well with r of 0.80, SEP of 0.210 %Brix and bias of 0.022 %Brix.