An ab initio topographical investigation on the molecular electrostatic potential of some chemical mutagens

A detailed topographical investigation on the molecular electrostatic potentials (MESPs) of different conformers of acetaldehyde, nitrous acid and hydroxylamine has been carried out at the ab initio SCF level using TZ2p, 6-31G* and STO-3G basis sets. In general, large regions of negative potential have been observed. An attempt has been made to correlate these potentials with biological activities of the molecules. Mutagenic and toxicological properties appear to be related to the presence of these large negative zones

Mobile gaze tracking system for outdoor walking behavioral studies

Most gaze tracking techniques estimate gaze points on screens, on scene images, or in confined spaces. Tracking of gaze in open-world coordinates, especially in walking situations, has rarely been addressed. We use a headmounted eye tracker combined with two inertial measurement units (IMU) to track gaze orientation relative to the heading direction in outdoor walking. Head movements relative to the body are measured by the difference in output between the IMUs on the head and body trunk. The use of the IMU pair reduces the impact of environmental interference on each sensor. The system was tested in busy urban areas and allowed drift compensation for long (up to 18 min) gaze recording. Comparison with ground truth revealed an average error of 3.38 while walking straight segments. The range of gaze scanning in walking is frequently larger than the estimation error by about one order of magnitude. Our proposed method was also tested with real cases of natural walking and it was found to be suitable for the evaluation of gaze behaviors in outdoor environments

Chemical looping combustion of biomass for renewable & non- CO2 emissions energy- status and review

World depends on fossil fuel combustion for thermal energy generation. Fossil fuel combustion leads to the generation of CO2 and ex-tinction of non-renewable resources. To meet the future energy demands replacement of existing technologies should take place in the view of large quantities of GHG’s emissions from fossil fuels and their extinction. Chemical looping combustion (CLC) is primarily a combustion technique with an inherent separation of CO2 from the flue gases. Due to its advantage of negative CO2 emissions, chemical looping combustion got attention of many researchers since last one and half decade. Recent research advancements in the CLC provided a platform for further research and developments in chemical looping combustion of biomass. This paper reviews the CLC of biomass to present the overview of chemical looping combustion technology and its status of biomass utilization as a fuel in CLC reactors

Investigation of diesel engine for low exhaust emissions with different combustion chambers

Upcoming stringent Euro-6 emission regulations for passenger vehicle better fuel economy, low cost are the key challenges for engine development. In this paper, 2.2L, multi cylinder diesel engine have been tested for four different piston bowls designed for compression ratio of CR 15.5 to improve in cylinder performance and reduce emissions. These combustion chambers were verified in CFD at two full load points. 14 mode points have been derived using vehicle model run in AVL CRUISE software as per NEDC cycle based on time weightage factor. Base engine with compression ratio CR16.5 for full load performance and 14-mode points on Engine test bench was taken as reference for comparison. The bowl with flat face on bottom corner has shown reduction 25% and 12 % NOx emissions at 1500 and 3750 rpm full load points at same level of Soot emissions. Three piston bowls were tested for full load performance and 14 mode points on engine test bench and combustion chamber ‘C’ has shown improvement in thermal efficiency by 0.8%. Combinations of cooled EGR and combustion chamber ‘C’ with geometrical changes in engine have reduced exhaust NOx, soot and CO emissions by 22%, 9 % and 64 % as compared to base engine at 14 mode points on engine test bench

Topographical analysis of electron density and molecular electrostatic potential for cyclopropa- and cyclobutabenzenes

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Complementary electrostatics for the study of DNA base-pair interactions

The complementary "lock and key" patterns of weakly interacting molecules are explored by mapping the topography of respective molecular electrostatic potentials (MESP). A new model, viz., electrostatic potential for intermolecular complexation (EPIC), which incorporates such MESP features, has been employed for studying interactions between DNA base pairs. A wide variety of pairs of bases involving adenine (A), guanine (G), and cytosine (C) are chosen as test cases. The interaction energy within the EPIC model is expressed as (½){∑VA,iqB,i + ∑VB,iqA,i}, where VA,i is the MESP value due to A at the ith atom of molecule B and qB,i is the MESP-derived charge at this site. The interaction energies and geometrical parameters obtained by this model agree remarkably well with the corresponding literature values obtained by full geometry optimization at the ab initio level. Being intuitively appealing and simple in application, the EPIC model seems to have the potential of being a good predictive tool for investigating weak intermolecular interactions

Structure and stability of DNA base trimers: an electrostatic approach

Triplexes involving major groove binding of a third oligomer to the DNA duplex structure have gathered much interest in recent years. The study of base trimer interactions in the gas phase is expected to provide useful information regarding orientational preferences and inherent stabilities. A recently developed electrostatic potential for intermolecular complexation (EPIC) model has been found to be quite useful for exploring the structures and energetics in base pairs [Gadre, S. R.; Pundlik, S. S. J. Phys. Chem. 1996, 101, 3298]. This model makes use of complementary electrostatic features of the interacting species that are determined by ab initio theory. We report here the investigations on various trimers including TAT, TAG, ATG, CGG, and TCG using this model. The overall good agreement of the trimer interaction energies with the corresponding single-point SCF values made at the model-predicted geometries reveals the suitability of the EPIC model for studying DNA base complexes