Using L‐Arginine‐Functionalized Gold Nanorods for Visible Detection of Mercury(II) Ions

A rapid and simple approach for visible determination of mercury ions (Hg²⁺) in aqueous solutions was developed based on surface plasmon resonance phenomenon using L‐arginine‐functionalized gold nanorods (AuNRs). At pH greater than 9, the deprotonated amine group of L‐arginine on the AuNRs bound with Hg²⁺ leading to the side‐by‐side assembly of AuNRs, which was verified by transmission electron microscopy images. Thus, when Hg²⁺ was present in the test solution, a blue shift of the typical longitudinal plasmon band of the AuNRs was observed in the ultra violet‐visible‐near infrared (UV‐Vis‐NIR) spectra, along with a change in the color of the solution, which occurred within 5 min. After carefully optimizing the potential factors affecting the performance, the L‐arginine/AuNRs sensing system was found to be highly sensitive to Hg²⁺, with the limit of detection of 5 nM (S/N = 3); it is also very selective and free of interference from 10 other metal ions (Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cs⁺, Cu²⁺, K⁺, Li⁺, Ni²⁺, Pb²⁺). The result suggests that the L‐arginine‐functionalized AuNRs can potentially serve as a rapid, sensitive, and easy‐to‐use colorimetric biosensor useful for determining Hg²⁺ in food and environmental samples.     

Effects of entrainment and agglomeration of particles on combustion of nano-aluminum and water mixtures

The combustion of nano-aluminum and water mixtures is studied theoretically for a particle size of 80 nm and over a pressure range of 1–10 MPa. Emphasis is placed on the effects of entrainment and agglomeration of particles on the burning rate and its dependence on pressure. The flame thickness increases by a factor of ∼10, when particle entrainment is considered. This lowers the conductive heat flux at the ignition front, thereby reducing the burning rate. The pressure dependence of the burning rate is attributed to the changes in the burning time and velocity of particles with pressure. In the diffusion limit, the pressure exponent increases from 0 to 0.5, when the entrainment index increases from 0 to 1.0. A similar trend is observed in the kinetics-controlled regime, although the corresponding value exceeds the diffusion counterpart by 0.5. The kinetics-controlled model significantly over-predicts the burning rate and its pressure exponent, depending on the entrainment index. The present analysis suggests that nano-particles formed closely-packed agglomerates of diameter 3–5 μm, which may burn under diffusion-controlled conditions at high pressures.     

Study of friction welding characteristics of Al/SiC composite and application of grey-based TOPSIS

The present work investigates the possibility of producing friction welded joints with an advanced material like Al/SiC (aluminum–silicon carbide) composite. The study also discloses the multi response optimization in the process of continuous drive friction welding using a hybrid algorithm of grey-based TOPSIS (technique for order of performance by similarity to ideal solution). The friction welding parameters (frictional pressure, upset pressure, burn off length and rotational speed) were optimized considering the multiple performance characteristics such as proof stress, tensile strength, and microhardness. Taguchi’s L₂₇ orthogonal array was used for conducting the welding trials. The confirmation test was conducted at the optimal setting, to sort out the effectiveness of the proposed hybrid algorithm. The macro photographs of the joints and optical micrographs of the weld zone were studied. The scanning electron microscope images of the fractured surface were also examined to identify the failure mode of joints. The significant improvements in the performance characteristics prove the effectiveness of the grey-based TOPSIS method in experimental welding optimization.     

Effect of packing density on flame propagation of nickel-coated aluminum particles

The combustion-wave propagation of nickel-coated aluminum particles is studied theoretically for packing densities in the range of 10–100% of the theoretical maximum density. Emphasis is placed on the effect of packing density on the burning properties. The energy conservation equation is solved numerically and the burning rate is determined by tracking the position of the flame front. Atomic diffusion coefficients and reaction rate of isolated nickel-coated aluminum particles are input parameters to the model. The burning behaviors and combustion wave structures are dictated by the heat transfer from the flame zone to the unburned region. Five different models for the effective thermal conductivity of the mixture are employed. The impact of radiation heat transfer is also assessed. As a specific example, the case with a particle size of 79 μm is considered in detail. The burning rate remains nearly constant (<1 cm/s) up to a packing density of 60%, and then increases sharply toward the maximum value of 11.55 cm/s at a density of 100%. The Maxwell–Eucken–Bruggeman model of thermal conductivity offers the most accurate predictions of the burning rate for all loading densities.     

Restoration of saline greenhouse soil and its effect on crop’s growth through in situ field-scale electrokinetic technology

An in situ electrokinetic (EK) system was designed and applied to highly saline greenhouse soil with a view to investigating the effects of the EK process on growing crops. In situ EK tests in field scale were conducted on the salt accumulated lands in the greenhouse where cabbages and lettuces were being cultivated. A voltage gradient of 0.25–0.6 V cm^?1 was applied for 50 days in the cultivated lands. The changes in the process, viz. current, voltage, and soil temperatures, were monitored. After the EK process, the initial electrical conductivity (EC, 6.0 dS m^?1) of the soil was reduced to about 1.7 dS m^?1 homogeneously below the recommended value (2.5 dS m^?1). The growth rate of cabbages and lettuces under EK treatment was about twice higher than those in the untreated area. The present study revealed that the EK process encourages the growth of the crops considerably and also removes the salts in the soil efficiently during the growth of the crops.     

Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses

Soon after it was discovered that intense laser pulses of nanosecond duration from a ruby laser could anneal the lattice of silicon, it was established that this so-called pulsed laser annealing is a thermal process. Although the radiation energy is transferred to the electrons, the electrons transfer their energy to the lattice on the timescale of the excitation. The electrons and the lattice remain in equilibrium and the laser simply 'heats' the solid to the melting temperature within the duration of the laser pulse. For ultrashort laser pulses in the femtosecond regime, however, thermal processes (which take several picoseconds) and equilibrium thermodynamics cannot account for the experimental data. On excitation with femtosecond laser pulses, the electrons and the lattice are driven far out of equilibrium and disordering of the lattice can occur because the interatomic forces are modified due to the excitation of a large (10% or more) fraction of the valence electrons to the conduction band. This review focuses on the nature of the non-thermal transitions in semiconductors under femtosecond laser excitation.     

Improving after-the-fact tracing and mapping: supporting software quality predictions

The software engineering industry undertakes many activities that require generating and using mappings. Companies develop knowledge bases to capture corporate expertise and possibly proprietary information. Software developers build traceability matrices to demonstrate that their designs satisfy the requirements. Proposal managers map customers' statements of work to individual sections of companies' proposals to prove compliance. Systems engineers authoring interface specifications record design rationales as they make relevant decisions. We developed an approach to tracing and mapping that aims to use fully automated information retrieval techniques, and we implemented our approach in a tool called RETRO (requirements tracing on target).