Studies on chemical interactions between chlorosulphonated polyethylene and carboxylated nitrile rubber

Highly polar rubbers interact with each other through their active functional groups via condensation or substitution reactions at high temperature. Chlorosulphonated polyethylene (CSM) rubber is a highly reactive rubber, whose reactivity is due to the—SO₂Cl groups. When CSM reacts with carboxylated nitrile rubber (XNBR), a chemical reaction takes place between the two rubbers at high temperature. Dynamic mechanical analysis shows that CSM and XNBR form a homogeneous blend. Fourier transform infrared (FTIR) studies support that CSM/XNBR (50/50 w/w) is a thermally induced self-cross-linking blend, when cross-linking takes place through carboxylic groups of XNBR and — SO₂Cl groups or in-situ generated allyl chloride moieties of CSM. There is a loss of some — CN groups during cross-linking; this may be due to an attack on the — CN groups by HCl (produced during heating of CSM) in the presence of inherent moisture in the polymers. Due to cross-linking, an ester or amide type of linkage is formed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1761–1768, 1997     

Synthesis and Biological Evaluation of Pyrazoline and Pyrrolidine-2,5-dione Hybrids as Potential Antitumor Agents

In search of novel and effective antitumor agents, pyrazoline-substituted pyrrolidine-2,5-dione hybrids were designed, synthesized and evaluated in silico, in vitro and in vivo for anticancer efficacy. All the compounds exhibited remarkable cytotoxic effects in MCF7 and HT29 cells. The excellent antiproliferative activity toward MCF7 (IC₅₀=0.78±0.01 μM), HT29 (IC₅₀=0.92±0.15 μM) and K562 (IC₅₀=47.25±1.24 μM) cell lines, prompted us to further investigate the antitumor effects of the best compound S2 (1-(2-(3-(4-fluorophenyl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione). In cell-cycle analysis, S2 was found to disrupt the growth phases with increased cell population in G₁/G₀ phase and decreased cell population in G₂/M phase. The excellent in vitro effects were also supported by inhibition of anti-apoptotic protein Bcl-2. In vivo tumor regression studies of S2 in HT29 xenograft nude mice, exhibited equivalent and promising tumor regression with maximum TGI, 66 % (i. p. route) and 60 % (oral route) at 50 mg kg⁻¹ dose by both the routes, indicating oral bioavailability and antitumor efficacy. These findings advocate that hybridization of pyrazoline and pyrrolidine-2,5-dioes holds promise for the development of more potent and less toxic anticancer agents.     

A Review on Efficient Routing Mechanisms in Urban Scenario of Vehicular Ad-Hoc Networks

Efficient routing protocols are crucial for enabling secure communication among the highly mobile and self-configurable nodes in Vehicular Ad-Hoc Networks(VANETs). In this work, we present a performance evaluation of different routing protocols in VANETs based on the currently available research. Our study focuses on analyzing the strength and weaknesses of the routing protocols, namely, Ad-Hoc On-demand Distance Vector(AODV), Dynamic Source Routing(DSR), and Destination-Sequenced Distance-Vecto...     

Impact of β-Sheet Conformations on the Mechanical Response of Protein in Biocomposites

Proteins in biological nanocomposites play an important role in their mechanical response. Proteins in nacre, the inner layer of seashells, have been shown to have exceptional mechanical properties. One of the important nacre proteins, Lustrin-A, has abundance of polypeptides in zig-zag conformation called β-sheets. β-sheets of protein when present close to each other in multiple numbers could take the shape of a planar β-sheath like structure or a β-barrel to form a domain. In natural proteins both these types of structures are commonly found. However, the conformation of β-sheets in Lustrin-A is not known at this time. Effort has been made through this work to study the mechanical response of these β-planar sheath and β-barrel structures when subjected to external loads. Comparative study of the stress-deformation characteristics of these two types of structures has been made. Both these structures with almost similar number of amino acids have been extracted from one single spinach protein: Ferredoxin Reductase (1FNR). Steered molecular dynamics has been used to conduct these studies. The article deals with the separation of the two domains from the main protein, simulation details, and results comparing the responses.     

Availability of 1-Server 2-Dissimilar Unit System with Slow Switch

The paper describes a 1-server 2-dissimilar unit cold standby redundant system with slow switch. Explicit expressions for the Laplace transform of mean up-time of the system and the steadystate availability of the system are also obtained in the Supplement.     

Structural,electrical and magneto-electric characteristics of complex multiferroic perovskite Bi<Subscript>0.5</Subscript>Pb<Subscript>0.5</Subscript>Fe<Subscript>0.5</Subscript>Ce<Subscript>0.5</Subscript>O<Subscript>3</Subscript>

The polycrystalline sample of bismuth based-complex multiferroic of a composition Bi_0.5Pb_0.5Fe_0.5Ce_0.5O₃ was prepared by a high-temperature solid-state reaction technique (calcinations temperature = 900 °C, sintering temperature = 960 °C, time = 4 h). Preliminary structural analysis using XRD data exhibits the formation of a single-phase compound. Studies of surface morphology of the ceramic sample of the compound, recorded at room temperature using a scanning electron microscope, show uniform distribution of grains of different size with few voids. Detailed studies of dielectric properties (ε_r, tan δ) supported the existence of multiferroic properties in the above complex system. The analysis of impedance parameters, recorded in a wide frequency (1 kHz–1 MHz) and temperature (room temperature to 450 °C) range of the material provide better understanding of (a) role of grains and grain boundaries in resistive and capacitative characteristics, (c) structure-properties relationship and (b) type of relaxation process occurred in the material. Study of temperature dependence of dc conductivity of the compound shows the existence of negative temperature coefficient of resistance in it. The nature of variation of ac conductivity with temperature of the material follows the Josher’s universal power law. Study of magneto-electric characteristics of the sample at room temperature has provided many useful and new data on magneto-electric coupling coefficient of different orders.     

Magnetism induced by nonmagnetic dopant in Li<Subscript>2</Subscript>O,Na<Subscript>2</Subscript>O,K<Subscript>2</Subscript>O and Rb<Subscript>2</Subscript>O: first-principles calculations

First-principles calculations based on the tight-binding linear muffin-tin orbital (TB-LMTO) method are performed to investigate the occurrence of spin polarization in the alkali-metal oxides (M₂O) [M: Li, Na, K, Rb] in antifluorite (anti-CaF₂-type) structure with non-magnetic sp (F, Cl, Br and I) dopants. The calculations reveal that non-magnetic substitutional doping at cation site can induce stable half-metallic ferromagnetic ground state in I₂-VI compounds. Total energy calculations show that the antifluorite ferromagnetic state is energetically more stable than the antifluorite non-magnetic state at equilibrium volume. Ground state properties such as equilibrium lattice constant and bulk modulus were calculated. The calculated magnetic moment is found to be 2.00 μB per dopant atom.