Silicon Seed Priming Combined with Foliar Spray of Sulfur Regulates Photosynthetic and Antioxidant Systems to Confer Drought Tolerance in Maize (Zea mays L.)

Silicon - The present study evaluated the effect of silicon (Si) seed priming and sulfur (S) foliar spray on drought tolerance of two contrasting maize hybrids viz. drought tolerant Hi-Corn 11 and...     

Destruction of percolative network using green synthesized gold nanoparticles: Formation of high dielectric material

Gold nanoparticles (AuNPs) of about 5 nm in diameter were biosynthesized at room temperature (300 K). The PVA/2.5 wt% KH₂PO₄ or KDP composite film and PVA/2.5 wt% KDP/AuNPs nanocomposite films with different concentrations of AuNPs were prepared. Interestingly, addition of 0.05 wt% of AuNPs to the PVA/2.5 wt% KDP percolative composite film destroys percolative behavior of this composite film. Furthermore, the PVA/2.5 wt% KDP/0.05 wt% AuNPs nanocomposite film exhibited high room temperature dielectric permittivity (ε′ ∼ 590 at 1 kHz). The behavior of AC conductivity (σ_ac) of the nanocomposite films indicated correlated barrier hopping type of conduction mechanism. The Cole–Davidson dielectric response becomes evident as the interfacial polarization process acquires a more symmetric form, tending to Debye relaxation. High value of ε′ promises direct application in capacitors. Moreover, the novel feature of destroying the percolative behavior by AuNPs may be applied even in other systems.     

Catalytic decomposition of biomass tars with iron oxide catalysts

Catalytic gasification of wood (Cedar) biomass was carried out using a specially designed flow-type double beds micro reactor in a two step process: temperature programmed non-catalytic steam gasification of biomass was performed in the first (top) bed at 200–850 °C followed by catalytic decomposition gasification of volatile matters (including tars) in the second (bottom) bed at a constant temperature, mainly 600 °C. Iron oxide catalysts, which transformed to Fe₃O₄ after use possessed catalytic activity in biomass tar decomposition. Above 90% of the volatile matters was gasified by the use of iron oxide catalyst (prepared from FeCl₃ and NH_3aq) at SV of 4.5 × 10³ h^?1. Tar was decomposed over the iron oxide catalysts followed by water gas shift reaction. Surface area of the iron oxide seemed to be an important factor for the catalytic tar decomposition. The activity of the iron oxide catalysts for tar decomposition seemed stable with cyclic use but the activity of the catalysts for the water gas shift reaction decreased with repeated use.     

Studies on the overall safety aspects during irradiation of TeO2 in the central thimble of the TRIGA research reactor

The purpose of this study is to provide a detailed safety analysis of overall system and components in terms of their ability to provide optimum output from the irradiation of TeO₂ in the central thimble of the 3 MW TRIGA MARK II research reactor at Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh. It identifies safety issues relevant to ¹³¹I radioisotope production and ensures that safety analysis and design are consistent. It evaluates threats developed within the facility during the irradiation process and ultimately ensures establishment of in-core safety limits and conditions at all stages of ¹³¹I production. In-core irradiation safety not only ensures the safe operation of the reactor but also strengthens the production of radioisotopes (RI). This study attempts to review and modify all safety related events and aspects relating to RI production. The three-dimensional continuous energy Monte Carlo code MCNP is used to develop a versatile and accurate full-core model of the TRIGA core. The cross-section library and fission product inventory are generated by using NJOY and ORIGEN computer codes. The methodology to evaluate heat generation and other relevant parameters necessary to provide enough information for thermal hydraulic analysis are discussed. The neutron flux distribution inside the dry and water filled central thimble is determined in order to locate the highest neutron flux trapping position. The thermal hydraulic and safety analysis are performed by elaborate numerical analysis as well as by using GENGTC computer code. A mock-up facility has also been developed to supplement and verify the theoretically predicted results. The total energy generated during irradiation of 50 gm TeO₂ sample in dry condition is found to be 113.84 w of which 75% energy is due to neutron heating and rest of the amount is from gamma heating. Around 11.28 w of heat energy is also generated in the quartz vial. When the total generated-heat transfer is considered through conduction and radiation mechanisms, the calculated temperature of 50 g of TeO₂ reaches at 970 °C. Considering simultaneous heat transfer mechanisms, (conduction, radiation and convection) the calculated maximum temperature of the 50 g of TeO₂ powder comes down at 680 °C. It may be pointed out that very high amount of heat is generated during the irradiation of TeO₂ at 3 MW reactor power in dry condition which is nearly the melting point of TeO₂ and may be termed as unsafe mode of irradiation.     

A rotor lamination design for surface permanent magnet retention athigh speeds

A major problem in the design and manufacturing of surface mounted permanent magnet machines is reliably holding the permanent magnets in place at high speeds. This paper evaluates a unique rotor lamination design for a high pole number, permanent magnet alternator. This buried magnet design, which is capable of reliably holding the permanent magnets in place at high speeds, offers both easier and cheaper assembly when compared with the methods currently used in surface mounted permanent magnet machines. Finite element analysis is used to compare the buried magnet design with equivalent surface mounted designs and shows that the performance of the alternator is not significantly affected by the iron over the magnets. Experimental results from a prototype alternator further corroborate the FEA and show that the design is capable of operating at high speeds with no other means of magnet retention. In addition, an improvement in the buried magnet design which can reduce the lamination complexity is suggested and examined     

Dehydration of ethyl alcohol on alumina-coated silica

Catalysts were prepared by precipitation of aluminium hydroxide on a wet silica gel. The dehydration of ethyl alcohol on catalysts varying in alumina content was studied at 307° using a flow system. The products of dehydration were ethylene, ether and water. The kinetics of the formation of ethylene followed the Langmuir-Hinshelwood mechanism, while the formation of ether occurred according to the Langmuir-Hinshelwood mechanism and the Rideal-Eley mechanism simultaneously. The catalytic activity was controlled by the amount of aluminium on the surface. The rate constants were correlated with the surface nature of the catalysts.     

Combined crease recovery finishing and pigment printing

The combined application of crease recovery finishing (using a dimethyloldihydroxyethylene urea-based finish) and pigment printing is evaluated in this study. The use of a small amount of ammonium chloride in a combined print–finish process induces significant pigment print paste viscosity losses. However, the catalyst 2-aminoethanesulphonic acid produces negligible viscosity reduction when used in the combined print–finish process, coupled with the desired levels of finish and pigment print performance. Similar dry crease recovery, breaking load, colour strength and colour fastness properties are achieved by using 2-aminoethanesulphonic acid in the combined print–finish process relative to the conventional print–finish process.     

Risk-Based Evaluation for Meeting Future Water Demand of the Brahmaputra Floodplain Within Bangladesh

A risk-based evaluation is performed for meeting future water demands in the Brahmaputra Floodplain Area within Bangladesh (BFA). This evaluation is carried out using three risk-based performance indicators: reliability, resiliency and vulnerability. The vulnerability indicator has been redefined incorporating the aspect of a supply failure. The analysis includes the impacts of climate change on both water demands and resources, and the generation of synthetic flows of the Brahmaputra River using time series models. The simulated values of the indicators reveal that the expected demand of the BFA up to the year 2050 can be supplied with the proposed Brahmaputra Barrage inside Bangladesh under the ‘no change’ in climatic condition, provided that the groundwater remains usable. However, if groundwater becomes unusable due to widespread arsenic contamination and/or a climate change occurs, it would not be possible to meet the future water demand of the region with high reliability, moderate resiliency and low vulnerability.     

Effect of operating factors on liquid–liquid mass transfer and dispersion pattern of sedimentary liquid in a mechanically stirred vessel

Liquid–liquid dispersion and mass transfer were investigated in mechanically stirred vessels without baffles by changing operation factors such as an impeller rotation speed, off-bottom clearance, volumetric liquid ratio, etc. The dispersion regime was categorized into five groups: the sedimentary liquid was kept at the vessel bottom (I), partially elevated without any collision (II), partially dispersed by colliding with the impeller bottom (III), both liquids were partially dispersed by collisions with impeller blades (III’), and the sedimentary liquid was completely dispersed (IV). The dispersion switched to I → II → III → IV with the increasing rotation speed and decreasing off-bottom clearance. The liquid–liquid mass transfer rate was significantly enhanced with the collision of the sedimentary liquid with the impeller bottom, and subsequently increased with the increasing rotation speed, volumetric liquid ratio, and vessel diameter and with the decreasing off-bottom clearance. A multiple regression analysis method was applied to determine the mass transfer rates of III and III’.     

Effect of Newtonian Heating and Thermal Radiation on Heat and Mass Transfer of Nanofluids over a Stretching Sheet in Porous Media

Laminar boundary layer slip flow from a stretching surface in a nanofluid‐saturated homogenous, isotropic porous medium is studied numerically. A Newtonian heating boundary condition in the presence of thermal radiation is incorporated and a Darcy model utilized for the porous medium. The model used for the nanofluids include the effects of Brownian motion and thermophoresis. A group theoretical analysis is conducted to generate similarity transformations. The governing transport equations are nondimensionalized and rendered into a set of coupled similarity ordinary differential equations using similarity transformations. The transformed equations are then solved using the Runge–Kutta–Fehlberg fourth‐fifth order numerical method with shooting technique. It is shown that the physical quantities of interest depend on a number of parameters. The results are presented in tabular and graphical forms. Comparison of the present numerical solutions with published work shows very good agreement. The study finds applications in high‐temperature nanotechnological materials processing.