Combustion of dried animal dung as biofuel results in the generation of highly redox active fine particulates

Background  

The burning of biomass in the developing world for heating and cooking results in high indoor particle concentrations. Long-term exposure to airborne particulate matter (PM) has been associated with increased rates of acute respiratory infections, chronic obstructive lung disease and cancer. In this study we determined the oxidative activity of combustion particles derived from the biomass fuel dung cake by examining their capacity to deplete antioxidants from a model human respiratory tract lining fluid (RTLF). For comparison, the observed oxidative activity was compared with that of particles derived from industrial and vehicular sources.     

Spectral studies on cellulose treated with sodium deuteroxide

Cellulose II and cellulose I samples were treated respectively with a strong solution of sodium deuteroxide in D₂O and a 99% solution of ethylenediamine. The complexes were washed with D₂O and the nature of the OD bands were studied after rehydrogenating the sample. The infrared spectra of these rehydrogenated samples showed well-resolved OD bands which are resistant to reexchange. The Characteristic bands are discussed and compared with the predicted OH-OD frequency shifts.     

Load redistribution mechanism in damage tolerant and redundant truss structure

Structural optimization for damage tolerance under various unforeseen damage scenarios is computationally challenging. It couples non-linear progressive failure analysis with sampling based stochastic analysis of random damages. This work shows that analysis of damage tolerance depends on specification of damages, and optimizing a structure under one damage specification can be sensitive to other damages not considered. This work demonstrates the importance of understanding the underlying mechanics that provide damage tolerance in order to develop computationally efficient methods for optimization. Understanding features of load distributions in damage tolerant structures can result in efficient methods for optimization. To understand and identify these features, one compared and contrasted designs with varying degree of damage tolerance. A method to describe load distributions based on principal component analysis is presented. It is found that the number of dominant eigenvalues of principal components in a structure correlates with the number of alternate paths.     

Flavour production in plant cell cultures of basmati rice (Oryza sativa L)

Callus cultures of naturally flavoured rice (Oryza sativa var 370) called basmati were obtained on Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid and kinetin. There was a perceptible basmati flavour in fresh callus. The volatile flavour components of basmati rice and callus were obtained by steam distillation-solvent extraction and were analysed on GC-MS. A qualitative comparison of volatile flavour components of callus cultures and natural basmati rice was also made. The results show the presence of 29 major compounds in rice and 23 in callus. The identified compounds include hydrocarbons, ketones, aldehydes, alcohols and esters. This demonstrated the potential of callus of basmati rice for flavour development.     

Graphene-based engine oil nanofluids for tribological applications

Ultrathin graphene (UG) has been prepared by exfoliation of graphite oxide by a novel technique based on focused solar radiation. Graphene based engine oil nanofluids have been prepared and their frictional characteristics (FC), antiwear (AW), and extreme pressure (EP) properties have been evaluated. The improvement in FC, AW, and EP properties of nanofluids is respectively by 80, 33, and 40% compared with base oil. The enhancement can be attributed to the nanobearing mechanism of graphene in engine oil and ultimate mechanical strength of graphene.     

Multi-hop Multi-band Intelligent Relay-Based Architecture for LTE-Advanced Multi-hop Wireless Cellular Networks

In recent years, the cellular spectrum has become very crowded due to the tremendous success of mobile communications. However, a large portion of the electromagnetic spectrum assigned to other services is used sporadically only. A first step towards cognitive radio can be implemented in LTE-advanced networks by sensing the available frequencies and exploiting the existing radio spectrum opportunistically in order to improve its utilization. In this paper, novel multi-hop multi-band intelligent (MMI) radio architecture is proposed for LTE-advanced cellular networks that would make use of a number of intelligent gateways in order to enable simultaneous usage of spectrum resources within the same cell. It relies on a multi-band network model with increasing number of channels which exponentially reduces the time required for resource allocation. Importantly, an analytical model has been proposed to describe the effects of fading on optimum position of gateway. This model was found to have a very close match with the simulation results, in the calculation of mean, standard deviation and the statistically carried out $t$ tests. Further, the two-hop architecture provides a significant increase in the system capacity. With nine bands and 50 nodes in the network, the MMI based two-hop design provides up to 150 % higher than that offered by a single-hop cellular design and with up to 40 % higher than when a state-of-the-art two-hop routing technique is employed.     

Influence of samarium doping on structural and dielectric properties of strontium bismuth tantalate ceramics derived by molten salt synthesis route

Layered Sr(Bi_1?xSm_x)₂Ta₂O₉ ceramics with x ranging from 0 to 0.10 (10 mol%) were fabricated by the low temperature molten salt synthesis route. X-ray powder diffraction studies revealed that the single phase orthorhombic layered perovskite structure is retained in all these compositions. Scanning electron microscopic studies on these ceramics confirmed the presence of well packed equiaxed plate shaped grains. The dielectric and electrical conductivity properties were studied in the 100 Hz–1 MHz frequency range at 300 K. Interestingly, the 10 mol% samarium doped SrBi₂Ta₂O₉ ceramics exhibited high dielectric constant (ε_r = 155) and low dielectric loss (0.00298) compared to those of other compositions. The electrical conductivity of undoped and samarium doped ceramics increased linearly with increase in frequency.     

3D Micro‐Extrusion of Graphene‐based Active Electrodes: Towards High‐Rate AC Line Filtering Performance Electrochemical Capacitors

A facile one‐step printing process by 3D micro‐extrusion affording binder‐free thermally reduced graphene oxide (TRGO) based electrochemical capacitors (ECs) that display high‐rate performance is presented. Key intermediates are binder‐free TRGO dispersion printing inks with concentrations up to 15 g L^?1. This versatile printing technique enables easy fabrication of EC electrodes, useful in both aqueous and non‐aqueous electrolyte systems. The as‐prepared TRGO material with high specific surface area (SSA) of 593 m² g^?1 and good electrical conductivity of ≈16 S cm^?1 exhibits impressive charge storage performances. At 100 and 120 Hz, ECs fabricated with TRGO show time constants of 2.5 ms and 2.3 ms respectively. Very high capacitance values are derived at both frequencies ranging from 3.55 mF cm^?2 to 1.76 mF cm^?2. Additionally, these TRGO electrodes can be charged and discharged at very high voltage scan rates up to 15 V s^?1 yielding 4 F cm^?3 with 50% capacitance retention. Electrochemical performance of TRGO electrodes in electrolyte containing tetraethyl ammonium tetrafluoroborate and acetonitrile (TEABF4‐ACN) yields high energy density of 4.43 mWh cm^?3 and power density up to 42.74 kW cm^?3, which is very promising for AC line filtering application and could potentially substitute state of the art electrolytic capacitor technology.     

Phase transformations—a physicist’s perception

Echoing a recent remark by Prof. Ramaseshan, a perspective review is made of the field of phase transformation, highlighting areas that might appeal to physicists. Prominent in this category are the study of ground state structures, the study of phase diagrams and the study of kinetic phenomena. Enumeration of ground state structures calls for inputs from group theory as well as reliable potentials, and physicists are therefore well equipped to make significant contributions. The theoretical analysis of phase diagrams (concerning which much experimental information already exists) raises challenging questions in equilibrium statistical mechanics. Since the problems map to Ising models of varying complexity and their generalizations, there are also very interesting connections to magnetism. Lately, computer simulation has added a new dimension, opening up fresh vistas both for theory and experiments. The study of kinetics belongs to the newly emerging area of non-equilibrium statistical mechanics. The focus being ontemporal phenomena, physicists can play a key role, particularly through the application of various types of relaxation spectroscopy. On the theoretical side too there are challenging problems, especially on account of the dominance of nonlinearities. Indeed if one is bold enough, one could even speculate on possible universalities underlying the complex microstructures invariably seen in late-stage evolution. In short, though the subject of phase transformations has thus far been nursed predominantly by metallurgists, there is enough room for physicists to make an independent entry and to make distinctive contributions. This paper was originally prepared for the 60th birthday volume of Prof. S Ramaseshan.