Mechanical property evaluation of glass–jute fiber reinforced polymer composites

The natural fibers such as jute, coir, hemp, sisal etc. are randomly used as reinforcements for composite materials because of its various advantages such as low cost, low densities, low energy consumption over conventional fibers. In addition, they are renewable as well as biodegradable, and indeed wide varieties of fibers are locally available. In this study, glass–jute fiber reinforced polymer composite is fabricated, and the mechanical properties such as tensile, flexural and impact behavior are investigated. The materials selected for the studies were jute fiber and glass fiber as the reinforcement and epoxy resin as the matrix. The hand lay‐out technique was used to fabricate these composites. Fractured surface were comprehensively examined in scanning electron microscope (SEM) to determine the microscopic fracture mode. A numerical procedure based on the finite element method was then applied to evaluate the overall behavior of this composite using the experimentally applied load. Results showed that by incorporating the optimum amount of jute fibers, the overall strength of glass fiber reinforced composite can be increased and cost saving of more than 30% can be achieved. It can thus be inferred that jute fiber can be a very potential candidate in making of composites, especially for partial replacement of high‐cost glass fibers for low load bearing applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Author index to volume 31

The problem of multiphoton absorption by an atom is formulated in terms of Brückner-Goldstone many-body perturbation theory with emphasis on the two-photon ionization of lithium. The series of terms in the perturbation expansion is summed up by using multiple basis sets. The result is represented by means of three primary diagrams. A more transparent interpretation of the ionization process is presented. Expressions for transition probabilities are obtained both for the linearly and circularly polarized photons. It is shown that the explicit introduction of the many-particle interaction does not change the angular distribution of the ejected electrons as compared to earlier calculations. The numerical results obtained for the transition probabilities in the limit of no correlation are found to agree with those of Mizuno.     

Synthesis and structure-activity relationship study of isoglobotrihexosylceramide analogues

Invariant natural killer T (iNKT) cells are innate T lymphocytes that express T cell receptors binding to exogenous and endogenous glycosphingolpid antigens presented by a nonpolymorphic, non-MHC antigen presenting molecule, CD1d. The endogenous glycosphingolipid metabolite, isoglobotrihexosylceramide (iGb3), is the first known natural ligand for both human and mouse iNKT cells, whose activity has been confirmed in a variety of iNKT cell clones generated by different investigators, representing the majority of the iNKT cell population. The signaling pathway mediated by T cell receptor is largely influenced by the structural variation of glycosphingolpid antigens, leading to multiple and varied biological functions of iNKT cells. In order to investigate the structural requirements behind iGb3 triggered iNKT cell activation, the structure-activity relationship (SAR) of iGb3 needs to be characterized. In this study, iGb3 analogues containing 2' ', 3' ', 4' ' and 6' ' deoxy terminal galactose were synthesized for probing the SAR between iGb3 and TCR. The biological assays on the synthetic iGb3 analogues were performed with use of the murine iNKT cell hybridoma DN32.D3. The results showed that the 2' ' and 3' ' hydroxyl groups of terminal galactose play more important roles for the recognition of iGb3 by TCR; while 4' ' and 6' ' hydroxyl groups were not as crucial for this recognition. These studies might help to understand the general structural requirements for natural endogenous ligands recognized by iNKT cells.     

Excitonically Coupled Cyclic BF2 Arrays of Calix[8]- and Calix[16]phyrin as Near-IR-Chromophores

Two giant calix[n]phyrin derivatives namely calix[8]- ( 4 ) and calix[16]phyrin ( 5 ), involving two and four BF₂ units, respectively, were prepared through the condensation of the bis-naphthobipyrrolylmethene-BF₂ complex ( 3 ) with pentafluorobenzaldehyde. Calix[n]phyrins 4 and 5 display extremely high extinction coefficients (3.67 and 4.82×10⁵ m ⁻¹ cm⁻¹, respectively) in the near-IR region, which was taken as initial evidence for strong excitonic coupling within these cyclic multi-chromophoric systems. Detailed insights into the effect of excitonic coupling dynamics on the electronic structure and photophysical properties of the macrocycles came from fluorescence, time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements. Support for these experimental findings came from theoretical studies. Theory and experiment confirmed that the coupling between the excitons depends on the specifics of the calix[n]phyrin structure, not just its size.     

A Glutathione Activatable Ion Channel Induces Apoptosis in Cancer Cells by Depleting Intracellular Glutathione Levels

Cancer cells use elevated glutathione (GSH) levels as an inner line of defense to evade apoptosis and develop drug resistance. In this study, we describe a novel 2,4‐nitrobenzenesulfonyl (DNS) protected 2‐hydroxyisophthalamide system that exploits GSH for its activation into free 2‐hydroxyisophthalamide forming supramolecular M⁺/Cl^? channels. Better permeation of the DNS protected compound into MCF‐7 cells compared to the free 2‐hydroxyisophthalamide and GSH‐activatable ion transport resulted in higher cytotoxicity, which was associated with increased oxidative stress that further reduced the intracellular GSH levels and altered mitochondrial membrane permeability leading to the induction of the intrinsic apoptosis pathway. The GSH‐activatable transport‐mediated cell death was further validated in rat insulinoma cells (INS‐1E); wherein the intracellular GSH levels showed a direct correlation to the resulting cytotoxicity. Lastly, the active compound was found to restrict the growth and proliferation of 3D spheroids of MCF‐7 cells with efficiency similar to that of the anticancer drug doxorubicin.     

Heat transfer characteristics of a porous radiant burner under the influence of a 2-D radiation field

This paper deals with the heat transfer analysis of a 2-D rectangular porous radiant burner. Combustion in the porous medium is modelled as a spatially dependent heat generation zone. The gas and the solid phases are considered in non-local thermal equilibrium, and separate energy equations are used for the two phases. The solid phase is assumed to be absorbing, emitting and scattering, while the gas phase is considered transparent to radiation. The radiative part of the energy equation is solved using the collapsed dimension method. The alternating direction implicit scheme is used to solve the transient 2-D energy equations. Effects of various parameters on the performance of the burner are studied.     

Indirect Analytic Representation of Foucault's Pendulum

A complex representation of the equations of motion of the Foucault's pendulum is considered and the inverse problem is solved to derive an indirect analytic representation. Both real L _R ⁽ⁱ⁾ and imaginary L _I ⁽ⁱ⁾ parts of the derived complex valued Lagrangian are found to reproduce the equations of motion via the Euler-Lagrange equations. The expressions for L _R ⁽ⁱ⁾ and L _I ⁽ⁱ⁾ are not connected by a gauge term thereby forming a set of inequivalent Lagrangians. In an appropriate limit L _I ⁽ⁱ⁾ is found to reproduce the Lagrangian obtained by implementing the usual Coriolis theorem while in some other limit L _R ⁽ⁱ⁾ and L _I ⁽ⁱ⁾ give the indirect and the direct analytic representations for a set of two uncoupled harmonic oscillators.     

Design and development of bioactive α-hydroxy carboxylate group modified MnFe2O4 nanoparticle: Comparative fluorescence study,magnetism and DNA nuclease activity

Three new α-hydroxy carboxylate group functionalized MnFe₂O₄ nanoparticles (NPs) have been developed to explore the microscopic origin of ligand modified fluorescence and magnetic properties of nearly monodispersed MnFe₂O₄ NPs. The surface functionalization has been carried out with three small organic ligands (tartrate, malate, and citrate) having different number of α-hydroxy carboxylate functional group along with steric effect. Detailed study unveils that α-hydroxy carboxylate moiety of the ligands plays key role to generate intrinsic fluorescence in functionalized MnFe₂O₄ NPs through the activation of ligand to metal charge transfer transitions, associated with ligand–Mn²⁺/Fe³⁺ interactions along with d–d transition corresponding to d–orbital energy level splitting of Fe³⁺ ions on NP surface. Further, MnFe₂O₄ NPs show a maximum 140.88% increase in coercivity and 97.95% decrease in magnetization compared to its bare one upon functionalization. The ligands that induce smallest crystal field splitting of d–orbital energy level of transition metal ions are found to result in strongest ferrimagnetic activation of the NPs. Finally, our developed tartrate functionalized MnFe₂O₄ (T-MnFe₂O₄) NPs have been utilized for studying DNA binding interaction and nuclease activity for stimulating their beneficial activities toward diverse biomedical applications. The spectroscopic measurements indicate that T-MnFe₂O₄ NPs bind calf thymus DNA by intercalative mode. The ability of T-MnFe₂O₄ NPs to induce DNA cleavage was studied by gel electrophoresis technique where the complex is found to promote the cleavage of pBR322 plasmid DNA from the super coiled form I to linear coiled form II and nicked coiled form III with good efficiency.