Effects of Silicon on Growth,Yield and Fruit Quality of Cantaloupe under Drought Stress

Silicon - Silicon (Si) plays an important role in mitigating adverse effects of various biotic and abiotic stresses including drought. Polyhouse experiment was conducted to evaluate the effects of...     

off-State Degradation in Drain-Extended NMOS Transistors: Interface Damage and Correlation to Dielectric Breakdown

Off-state degradation in drain-extended NMOS transistors is studied. Carefully designed experiments and well-calibrated simulations show that hot carriers, which are generated by impact ionization of surface band-to-band tunneling current, are responsible for interface damage during off-state stress. Classical on-state hot carrier degradation has historically been associated with broken equivSi-H bonds at the interface. In contrast, the off-state degradation in drain-extended devices is shown to be due to broken equivSi-O- bonds. The resultant degradation is universal, which enables a long-term extrapolation of device degradation at operating bias conditions based on short-term stress data. Time evolution of degradation due to broken equivSi-O- bonds and the resultant universal behavior is explained by a bond-dispersion model. Finally, we show that, under off-state stress conditions, the interface damage that is measured by charge-pumping technique is correlated with dielectric breakdown time, as both of them are driven by broken equivSi-O- bonds.     

Experimental study on hysteresis phenomena of shock wave structure in an over-expanded axisymmetric jet

In recent studies on two-dimensional supersonic jets, it is reported that the hysteresis phenomenon for the reflection type of shock waves in the jet flow field is occurred under the quasi-steady flow condition and this phenomenon is affected by the transitional pressure ratio between the regular reflection and Mach reflection. However, so far, there are few researches on the hysteresis phenomenon for the transition of shock waves between regular and Mach reflection in over-expanded supersonic jets and the phenomenon has not been investigated satisfactorily. Therefore, the purpose of this study is to clarify the hysteresis phenomena for the reflection type of shock wave in the over-expanded axi-symmetric supersonic jet experimentally, and to discuss the relationship between hysteresis phenomenon and rate of the change of pressure ratio with time. Furthermore, the effect of Mach number at the nozzle exit on hysteresis loop was investigated for two kinds of nozzle.     

Novel Near‐Infrared Squaraine Sensitizers for Stable and Efficient Dye‐Sensitized Solar Cells

A new molecular design strategy for tuning the energy levels of cis‐configured squaraine sensitizers for dye‐sensitized solar cells is described. The Hammett substituent constant and the π‐conjugation length are used as quantitative indicators to modify the central squarate moiety of the sensitizer dyes; specifically, novel near‐infrared squaraine dyes HSQ3 and HSQ4 are synthesized by incorporation of an electron‐withdrawing and π‐extending ethyl cyanoacetate unit on the central squarate moiety. The solution absorption maximum of HSQ4 occurs at 703 nm, and the energy levels of the lowest unoccupied molecular orbital and the highest occupied molecular orbital are in the ideal range for energetically efficient electron injection and regeneration of the oxidized dye. A solar cell sensitized with HSQ4 exhibits a broad incident photo­n‐to‐current conversion efficiency spectrum, extending into the near‐infrared region with a maximum value of 80% at 720 nm, which is is the highest value reported for a squaraine dye–based dye‐sensitized solar cell. The HSQ4‐sensitized solar cell also exhibits excellent durability during light soaking, owing to the double anchors attaching the dye to the TiO₂ surface and to the long alkyl chains extending outward from the surface.     

Deforestation and greenhouse gas emissions associated with fuelwood consumption of the brick making industry in Sudan

The study focuses on the role of the fired clay brick making industry (BMI) on deforestation and greenhouse gas (GHG) emissions in Sudan. The BMI is based on numerous kilns that use biomass fuel, mainly wood which is largely harvested unsustainably. This results in potential deforestation and land degradation. Fuelwood consumption data was collected using interviews and questionnaires from 25 BMI enterprises in three administrative regions, namely Khartoum, Kassala and Gezira. Annual fuelwood consumption data (t dm yr^− 1) was converted into harvested biomass (m³) using a wood density value of 0.65 t dm m^− 3. For annual GHG estimations, the methodological approach outlined by the Intergovernmental Panel on Climate Change (IPCC) was used. According to our results, the annual deforestation associated with the BMI for the whole of Sudan is 508.4 × 10³ m³ of wood biomass, including 267.6 × 10³ m³ round wood and 240.8 × 10³ m³ branches and small trees. Total GHG emissions from the Sudanese BMI are estimated at 378 028 t CO₂, 15 554 t CO, 1778 t CH₄, 442 t NO_X, 288 t NO and 12 t N₂O per annum. The combined CO₂-equivalent (global warming potential for 100-year time horizon) of the GHG emissions (excluding NO_X and NO) is 455 666 t yr^− 1. While these emissions form only a small part of Sudan's total GHG emissions, the associated deforestation and land degradation is of concern and effort should be made for greater use of sustainable forest resources and management.     

Epoxide functionalized γ-Al2O3/Fe3O4/SiO2 nanocomposite and comparative adsorption behavior of a model reactive azo dye

In this investigation, magnetic γ-Al₂O₃ nanocomposite polymer particles with epoxide functionality were prepared following a multistep process. The prepared nanocomposite polymer particle was named as γ-Al₂O₃/Fe₃O₄/SiO₂/poly(glycidyl methacrylate (PGMA). The surface property was evaluated by carrying out the adsorption study of Remazol Navy RGB (RN), a model reactive azo dye, on both γ-Al₂O₃/Fe₃O₄/SiO₂ and γ-Al₂O₃/Fe₃O₄/SiO₂/PGMA nanocomposite particles, that is, before and after epoxide functionalization. A contact time, temperature, adsorbent dose, and dye concentration dependent change in adsorption behavior was observed on both nanocomposite particles. The adsorption amount reached equilibrium (q_e) value within 5 minutes at the respective point of zero charge (PZC). The adsorption density of RN per unit specific surface area on epoxide functional γ-Al₂O₃/Fe₃O₄/SiO₂/PGMA nanocomposite polymer particles (1.30 mg/m²) was higher relative to that on γ-Al₂O₃/Fe₃O₄/SiO₂ nanocomposite particles (0.87 mg/m²). The optimum adsorbent dose for obtaining the maximum adsorption density was 0.01 g. Comparatively, Langmuir isotherm model was better to describe the adsorption process and the adsorption process was favorable at low temperature (283 K). Batch kinetic adsorption experiment suggested that a pseudo-second-order rate kinetic model is more appropriate. Nanocomposite polymer particles were used as adsorbent up to third cycle with almost 99% adsorption efficiency.     

Structure–property relationship of hetero‐aromatic‐electron‐donor antennas of polypyridyl Ru (II) complexes for high efficiency dye‐sensitized solar cells

Three novel heteroleptic amphiphilic polypyridyl Ru‐complexes, coded MH08–10 , with hetero‐aromatic electron‐donor ancillary ligands containing N‐benzylcarbazole ( MH08 ), dibenzofurane ( MH09 ) and benzothiophene moieties ( MH10 ) were synthesized to study the influence of different heterocyclic electron donors on the interrelationship of photophysical and electrochemical properties, and device performances for dye‐sensitized solar cells (DSSCs). MH08 showed a remarkably high molar extinction coefficient of 27,650 M⁻¹cm⁻¹. MH08–TBA was synthesized from MH08 by converted one COOH group into −COO⁻⁺N(C₄H₉)₄ to investigate the effect of deprotonating one carboxylic group on the Fermi level and electron injection. When compared under the same experimental device conditions using 0.3M t‐butylpyridine (TBP), the short‐circuit photocurrent density (J_SC) and total conversion efficiency (%η) of MH08–10 were MH08 > MH09 > MH10 . The differences in %η and J_SC of MH08–10 were ascribed to the conjugation length coupled with the electron donation and hole‐transport strength of the ancillary ligands, which were in the following order N‐benzylcarbazole>dibenzofurane>benzothiophene. Moreover, MH08–TBA showed J_SC of 19.56 mAcm⁻² and %η of 9.76% compared to 17.16 mAcm⁻² and 9.12% of the benchmark dye N719 . The superior performance of MH08–TBA was attributed to its better light harvesting and enhanced incident‐photon‐to‐current efficiency (IPCE) conversion. DFT/TD‐DFT calculations utilizing the energy functional B3LYP and the full‐electron basis set DGDZVP were performed to calculate HOMO and LUMO energies, vertical electronic excitations, lowest singlet‐singlet electronic transitions (E_0‐0), and excited state oxidation potentials. Excellent agreement was found between the experimental results and calculated data. Copyright © 2013 John Wiley & Sons, Ltd.     

CPFD flow pattern simulation in downer reactors

This study contributes with a computational fluid dynamic simulation based on the numerical solution of continuity and momentum balance equations in a three‐dimensional (3‐D) framework. The proposed down flow gas–solid suspension model includes a unit configuration and C_D drag coefficients recommended for these units. Computational particle fluid dynamics (CPFD) calculations using suitable boundary conditions and a Barracuda (version: 14.5.2) software allow predicting local solid densification and asymmetric “wavy flows.” In addition, this model forecasts for the conditions of this study higher particle velocity than gas velocity, once the flow reaches 1 m from the gas injector. These findings are accompanied with observations about the intrinsic rotational character of the flow. CPFD numerical 3‐D calculations show that both gas and particle velocities involve the following: (a) an axial velocity component, (b) a radial velocity component (about 5% of axial velocity component), and (c) an angular velocity component. The calculated velocity components and the rotational flow pattern are established for a wide range of solid flux/gas flux ratios. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1635–1647, 2013     

Proposal for dispersion compensating square-lattice photonic crystal fiber

A dispersion-compensating square-lattice photonic crystal fiber for broadband compensation which covers the S, C and L communication bands, i.e. wavelength ranging from 1 460 nm to 1 625 nm is proposed in this paper. Theoretically, it is shown a negative dispersion coefficient of about-595 ps/(nm·km) to-1 288 ps/(nm·km) over S to L bands and-975 ps/(nm·km) at the operating wavelength 1 550 nm. The relative dispersion slope is perfectly matched to that of conventional single-mode fiber of about 0.003 6 nm^-1. Besides the proposed photonic crystal fiber shows the large nonlinear coefficient of 61.88 W/km at the operating wavelength of 1 550 nm. Moreover, the variation of structural parameters is also studied and discussed here.