Effect of Extraction Techniques and Solvent Systems on the Extraction of Antioxidant Components from Peanut (Arachis hypogaea L.) Hulls

This research work was carried out to investigate the effect of different extraction techniques on antioxidant potential of peanut (Arachis hypogaea) hulls. The antioxidant extracts of peanut hulls (PH) were prepared using different extraction methods such as soaking, stirring, shaking, and sonicated-assisted stirring with methanol/water (80:20) and ethanol/water (80:20) solvents systems. The antioxidant potential of extracts was measured using different in vitro antioxidant assays like estimation of total phenolic contents (TPC), estimation of total flavonoids contents (TFC), DPPH-scavenging capacity, percentage inhibition of linoleic acid peroxidations, and bleachability of ?-carotene in linoleic acid system. TPC and TFC of different PH extracts were found in range of 1.23–8.43 mg/g of dry plant material, measured as gallic acid equivalent, 0.33–5.06 mg/g of dry plant material, measured as catechin equivelent (CE), respectively. All the PH extracts exhibited good free radical scavenging potential and moderate inhibition of linoleic acid peroxidation. Significant (p ≤ 0.05) variations were observed in the antioxidant potentials of various extraction methods and solvent systems. Among all the extraction methods, sonicated-assisted stirring showed better yield and antioxidant capacity. In view of the present findings, it is reasonable to say that different extracts of peanut hulls exhibited varying degree of antioxidant activity, which might be attributed to various mechanisms involved in extraction procedures.     

Thermal properties of ion beam irradiated polycarbonate films

Semicrystalline polycarbonate (PC) films were irradiated under vacuum at room temperature by C⁺⁵ beam of 55 MeV energy at fluences of 3 × 10¹¹ and 3 × 10¹³ ions cm². Ion induced modifications were studied by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and thermally stimulated discharge current (TSDC) techniques. With increasing ion fluence significant loss of average crystallite size, percentage crystallinity, stability and glass transition (T_g) temperature were observed. TSDC shows that activation energy, released charge, α-relaxation peak, and charge carrier mobility decrease while relaxation time and peak current increase.     

In search of materials for artificial flagella of nanoswimmers

Localized drug delivery and nano manipulation in fluid media like blood is an important application in biomedicine. Nanoswimmers are potential drug delivery agents for inter-vascular and intra-cellular systems. The bio-mimic modeling of flagellar propulsion mechanism of nanoswimmers has been widely attempted in literature. Mathematical models of the flagellated nanoswimmers show dependence of motion on multiple parameters like geometry and material of flagella, and viscosity of the surrounding medium. The literature also provides constraints to the material property depending on the mimicked biological system. Although modeling of shape and size of nanoswimmers is widely investigated in the literature, the material selection for the flagella needs to be assessed on the criteria like biocompatibility, physical properties, and technological feasibility. The shortlisting is quintessential for attempts to engineer an artificial nanoswimmer. The present study provides a methodology for assessing the candidature of a material for the fabrication of artificial flagella, which shall have implant capabilities and be able to shortlist the potential material. Further screening criteria, based on biocompatibility and technology viability issues are also discussed.     

Cognitive map-based system modeling for identifying interaction failure modes

Past few decades have seen an upsurge in failure analysis techniques capable of dealing with reliability issues up front in the early stages of the product development process. Most of these approaches are centered on component-specific failures. However, with the advent of highly complex systems that derive functionalities from multiple physical phenomena domains, more emphasis is required on identifying failures arising due to various system interactions, which is largely absent in existing failure analysis approaches. Owing to the causal nature of system interaction failures, the use of cognitive maps in system modeling and simulation for failure analysis is highly suitable. This paper proposes a structured framework for the development and use of cognitive map-based system models capable of capturing all types of failure modes, including interaction failures. The applicability of the proposed framework is demonstrated with the example of an electric water heater.     

Extrapolation of Mechanical Strengthening Effect in Nanoclay/Epoxy Nanocomposites to Elevated Temperature Environments

The economical nanoclay/polymer nanocomposite with laudable thermal and barrier properties motivates scientists for its potential exploration in widespread engineering applications. The present investigation has been focused on the mechanical durability study of these nanocomposites at above ambient temperature environment. In-situ flexural testing was performed on epoxy based nanocomposites with 0, 0.5, 1 and 3 wt% nanoclay content at various temperatures (30, 50, 70 and 90 °C). Addition of only 0.5 wt% nanoclay in epoxy resulted in 17 and 26% improvement in flexural strength and modulus respectively (which is maximum among all the materials), when tested at room temperature, due to highest degree of exfoliation of nanoclay as confirmed from XRD analysis. At higher testing temperatures, all the materials exhibited a decreasing trend in their mechanical properties and a positive reinforcement effect was evident even up to the close vicinity of glass transition temperature. These findings were further verified by dynamic mechanical thermal analysis in a wide range of temperature varying continuously from 40 to 200 °C. The degree of dispersion and possible deformation and failure mechanisms were identified by scanning electron microscope.     

An Improved Method for Ray Tracing Through Curved Inhomogeneities in Composite Materials

Ultrasonic NDE of anisotropic materials, due to its inherent complexity, demands a stringent approach to determine wave propagation path in presence of inhomogeneities. In addition to developing inspection procedures, the ray path information needs to be integrated with the tomographic reconstruction algorithm of composite materials. The present study proposes a method to identify inhomogeneity boundaries using edge detection approach and to implement the same in two-dimensional ray tracing model. In general, inhomogeneity boundaries can be detected on the basis of first-order gradient of a field value (such as Young's modulus). The boundaries can be represented in terms of location and orientation. This information is included in the algorithm for more accurate ray tracing. Examples show the usefulness of the method to take into effect poor penetration of ultrasound energy in certain regions of inhomogeneous materials.     

Controlled grafting of N-isoproply acrylamide brushes onto self-standing isotactic polypropylene thin films: surface initiated atom transfer radical polymerization

Surface initiated atom transfer radical polymerization (ATRP) technique using CuBr/CuBr₂/bpy complex is employed to graft N-isopropyl acrylamide (NIPAA) brushes onto ‘self-standing’ isotactic polypropylene (iPP) film surface via iPP-Br macro-initiator. The successful accomplishment of surface grafting is understood from the UV-Vis, ATR-FTIR, XPS, SEM analysis and contact angle measurements of the modified samples. The ability to control the degree of grafting of NIPAA brushes reaffirms the elegance of the surface initiated ATRP technique to develop tailor-made polymer surfaces. The LCST nature of the NIPAA brushes would introduce stimuli responsive character onto the surface of the iPP films used for various specialty applications, especially for biomedical purposes.