Multi-Model Approach to Assess the Dynamics of Hydrologic Components in a Tropical Ecosystem

Estimation of terrestrial water budget at global and regional scales are essential for efficient agricultural water management, flood predictions, and, hydrological modeling. In hydrological modeling, it is a challenging task to quantify the major hydrological components like runoff, evapotranspiration (ET), and total water storage (TWS) due to improper and limited availability of detailed meteorological datasets. Furthermore, there has been no consensus to answer a-decade-long critical question that a less data-intensive models can be an alternate to robust data-intensive models in data scarce conditions. This study aims at multi-model approach over the single models usage for representing the hydrological behaviour in the Kangsabati River Basin (KRB), India. It is done by applying the standard model selection criteria over various hydrological models. Two hydrological models are selected, a semi- distributed model, Variable Infiltration Capacity (VIC-3 L), and a conceptually lumped model, Identification of unit Hydrograph and Component flows from Rainfall, Evapotranspiration and Streamflow (IHACRES). Both models were calibrated against the observed daily discharge at the KRB outlet for the period of 2001–2006 and validated for 2008–2010. The results show that both VIC-3 L and IHACRES produce reasonable runoff estimates at daily and monthly time scale in the KRB. The ET estimates show that VIC-3 L and IHACRES captured the seasonal variations with the percent change of 0.4% and 6.6% respectively. As IHACRES is simpler, parsimonious, fewer parameters, and better performances, it can be useful for hydrological modeling in data-scarce regions.

     

Effect of divalent cation addition on structure,conductivity and grain boundary properties in La doped ceria oxygen ion conductors

The aim of this work is to investigate the effect of divalent cations on the structure and electrical properties of Ce_0.85La_0.1D_0.05O_2-δ (D = Ca, Sr and Ba) oxygen ion conductors. The X-Ray structural analysis confirms the presence of CeDO₃ minor phase in addition to cubic fluorite phase of ceria in Sr²⁺ and Ba²⁺ added compositions. The lattice parameter of the compositions significantly depends on the ionic radius of dopants and the presence of D²⁺ ions in ceria lattice. The Ca²⁺ added composition shows the highest free oxygen vacancy concentration due to its lowest association energy and complete dissolution of Ca²⁺ ions into ceria lattice. The dopant-vacancy association energy and grain interior conductivity changes with the ionic radii of the divalent dopants. The grain boundary capacitance depends on dielectric constant, grain size and grain boundary thickness. The grain boundary conductivity shows 46% over total conductivity for Sr²⁺ added composition. The presence of CeDO₃ phase and space charge layer promotes the grain boundary resistances and affects the ion dynamics. Schematic models are proposed to understand the ion migration in grain boundaries. The scavenging effect is found to be highest in Sr²⁺ ions added composition. The defect structures, the presence of CeDO3 phase and electrical properties are correlated with each other.     

Evolution of Anisotropic Arrow Nanostructures during Controlled Overgrowth

Anisotropic metal nanoparticles (NPs), such as high-aspect-ratio Au nanorods (NRs), play an important role for applications in photocatalysis, sensing, and drug delivery because of their adjustable plasmon resonances. Their performance for these applications can be further improved by fine-tuning their morphologies. Achieving desired NP architectures requires insight into their formation mechanisms. Here, liquid-phase transmission electron microscopy is used to directly follow the overgrowth of Au NR seeds into nanoarrows (NAs) with fourfold symmetric wings along the sides. Adding thiol molecules like L-cysteine to the growth solution can lead to the formation of NAs with periodic prismatic teeth instead of the straight side wings. These observations suggest that this transition is controlled by binding of L-cysteine to the NR surface, which in turn, slows down the metal deposition rate, switching the overgrowth from the kinetically to thermodynamically controlled process. Furthermore, simulations demonstrate that these prismatic teeth enhance the NPs’ plasmonic properties. The study describes how thiol additives control the morphological evolution of metal NPs, which is important for the fabrication of NPs with tailored shapes for a broad range of applications.     

Introducing Fractional-Order Dynamics to Sigma–Delta Modulators

The aim of the present paper is to investigate the performance of a fractional-order sigma–delta modulator wherein the integer-order integrator is replaced by a fractional integrator of order \( \alpha \,(1 <\alpha < 2)\). A generalized approach to both linear frequency domain and non-linear time domain modeling and characterization of fractional-order sigma–delta modulator has been discussed. The performance of such modulator has been studied and compared with the corresponding integer-order modulators through simulation.     

Binary Chiral Nanoparticles Exhibit Amplified Optical Activity and Enhanced Refractive Index Sensitivity

Metallic chiral nanoparticles (CNPs) with a nominal helical pitch (P) of sub‐10 nm contain inherent chirality and are promisingly applied to diverse prominent enantiomer‐related applications. However, the sub‐wavelength P physically results in weak optical activity (OA) to prohibit the development of these applications. Herein, a facile method to amplify the CNPs' OA by alloying the host CNPs with metals through a three‐step layer‐by‐layer glancing angle deposition (GLAD) method is devised. Promoted by the GLAD‐induced heating effect, the solute metallic atoms diffuse into the host CNPs to create binary alloy CNPs. Chiral alloying not only induces the plasmonic OA of the diffused solute and the created alloys but also amplifies that of the host CNPs, generally occurring for alloying Ag CNPs with diverse metals (including Cu, Au, Al, and Fe) and alloying Cu CNPs with Ag. Furthermore, the chiral alloying leads to an enhancement of refractive index sensitivity of the CNPs. The alloy CNPs with amplified plasmonic OA pave the way for potentially developing important chirality‐related applications in the fields of heterogeneous asymmetric catalysis, enantiodifferentiation, enantioseparation, biosensing, and bioimaging.     

The Effect of Minor Addition of Ni on the Microstructural Evolution and Mechanical Properties of Suction Cast Al-0.14 at. pct Sc Binary Alloy

Aluminum scandium binary alloys represent a promising precipitation-hardening alloy system. However, the hardness of the binary alloys decreases with the rapid coarsening of Al₃Sc precipitate during high-temperature aging. In the current study, we report a new approach to compensate for the loss of mechanical properties by combining rapid solidification with very small ternary addition of transition metal Ni. This addition yields dispersion, and at a critical concentration improves the mechanical properties. We explore additions of a maximum of 0.06 at. pct of Nickel to a binary Al-0.14 at. pct Sc alloy, which yield nickel-rich dispersions. We report two kinds of biphasic dispersions containing AlNi₂Sc/Al₉Ni₂ and α-Al/Al₉Ni₂ phase combinations. The maximum improvement in mechanical properties occurs with the addition of 0.045 at. pct Ni with a yield strength of 239 ± 7 MPa for an aging treatment at 583 K (310 °C) for 15 hours.