Silver nanoparticles of variable morphology synthesized in aqueous foams as novel templates

In this paper, we describe the synthesis of silver nanocrystals within aqueous foams as a template. More specifically, we show that aqueous Ag⁺ions may be electrostatically complexed with the anionic surfactants aerosol OT (sodiumbis-2-ethylhexyl-sulfosuccinate, (AOT) and sodium dodecyl sulphate (SDS)) in a highly stable liquid foam. After drainage of the foam, the silver ions are reducedin situby introducing sodium borohydride into the foam by capillary flow. This leads to the formation of silver nanoparticles of spherical, tape-and sheet-like morphology in the foam. The structure of the foam is extremely complex and presents reaction sites of different spatial extent. The differences in foam reaction-site geometry are believed to be responsible for the morphology variation in the silver nanoparticles observed. The silver nanoparticles are observed to be extremely stable in solution suggesting that the AOT or SDS molecules stabilize them. This approach appears promising for application in large-scale synthesis of nanoparticles and may be readily extended to other chemical compositions.     

Recent progress on graphene quantum dots-based fluorescence sensors for food safety and quality assessment applications

The versatile photophysicalproperties, high surface-to-volume ratio, superior photostability, higher biocompatibility, and availability of active sites make graphene quantum dots (GQDs) an ideal candidate for applications in sensing, bioimaging, photocatalysis, energy storage, and flexible electronics. GQDs-based sensors involve luminescence sensors, electrochemical sensors, optical biosensors, electrochemical biosensors, and photoelectrochemical biosensors. Although plenty of sensing strategies have been developed using GQDs for biosensing and environmental applications, the use of GQDs-based fluorescence techniques remains unexplored or underutilized in the field of food science and technology. To the best of our knowledge, comprehensive review of the GQDs-based fluorescence sensing applications concerning food quality analysis has not yet been done. This review article focuses on the recent progress on the synthesis strategies, electronic properties, and fluorescence mechanisms of GQDs. The various GQDs-based fluorescence detection strategies involving Förster resonance energy transfer- or inner filter effect-driven fluorescence turn-on and turn-off response mechanisms toward trace-level detection of toxic metal ions, toxic adulterants, and banned chemical substances in foodstuffs are summarized. The challenges associated with the pretreatment steps of complex food matrices and prospects and challenges associated with the GQDs-based fluorescent probes are discussed. This review could serve as a precedent for further advancement in interdisciplinary research involving the development of versatile GQDs-based fluorescent probes toward food science and technology applications.     

Effect of fuzzy C means technique in failure mode discrimination of glass/epoxy laminates using acoustic emission monitoring

Acoustic emission is one of the powerful techniques that can be used for in situ structural health monitoring of composite laminates. One of the main issues of AE is to characterize the different damage mechanisms from the detected AE signals. Unsupervised Pattern recognition has been one of the techniques used for the identification of a specific failure mode in composites from Acoustic emission data. Cross ply composite laminate of size 300 × 300 mm is fabricated using Vacuum bag molding. ASTM D3039 Standard tensile specimens are cut from the laminate and these specimens are subjected to uni axial tensile test under Acoustic Emission monitoring. Fast Fourier transform analysis (FFT) and Short Time Fast Fourier Transform (STFFT) analysis are performed on the Wave forms of the AE hit data obtained during the conduct of tensile test to characterize the failure modes in crossply specimens. Fast Fourier Transform enabled calculating the frequency content of each damage mechanism. In this paper Fuzzy C Mean clustering is performed for the AE parameters obtained from the test and the efficiency of this technique is being investigated using FFT AND STFFT analysis.     

Novel Li4Ti5O12/Sn nano-composites as anode material for lithium ion batteries

Li₄Ti₅O₁₂/Sn nano-composites have been prepared as anode material for lithium ion batteries by high-energy mechanical milling method. Structure of the samples has been characterized by X-ray diffraction (XRD), which reveals the formation of phase-pure materials. Scanning electron microscope (SEM) and transmission electron microscope (TEM) suggests that the primary particles are around 100 nm size. The local environment of the metal cations is confirmed by Fourier transform infrared (FT-IR) and the X-ray photoelectron spectroscopy (XPS) confirms that titanium is present in Ti⁴⁺ state. The electrochemical properties have been evaluated by galvanostatic charge/discharge studies. Li₄Ti₅O₁₂/Sn-10% composite delivers stable and enhanced discharge capacity of 200 mAh g⁻¹ indicates that the electrochemical performance of Li₄Ti₅O₁₂/Sn nano-composites is associated with the size and distribution of the Sn particles in the Li₄Ti₅O₁₂ matrix. The smaller the size and more homogeneous dispersion of Sn particles in the Li₄Ti₅O₁₂ matrix exhibits better cycling performance of Li₄Ti₅O₁₂/Sn composites as compared to bare Li₄Ti₅O₁₂ and Sn particles. Further, Li₄Ti₅O₁₂ provides a facile microstructure to fairly accommodate the volume expansion during the alloying and dealloying of Sn with lithium.     

Investigation on the Nonlinear Excitation in an Array of Spin Valve Pillars During the propagation of Electromagnetic Wave

We have investigated the nonlinear excitations in an array of spin valve pillars during the propagation of an electromagnetic wave. The flowing electrons exhibit spins transportation effect due to the torque experienced by the spin magnetization. From the Hamiltonian which models the spin interaction in a spin valve array, we have studied the effect of perturbation using multiple scale expansion and Reduction Perturbation method. The Landau–Lifshitz–Gilbert equation of magnetization, which models the evolution of magnetization of the ferromagnetic layer, is studied along with Maxwell’s equation for the electromagnetic waves. It is found that the system of equations reduce to the celebrated modified KdV equation. The solution of the spin excitations are localized solitons. The physically interesting solitons can be harnessed to the increase in density of memory devices.