Banaras Hindu University

About: Banaras Hindu University is a education organization based out in Varanasi, Uttar Pradesh, India. It is known for research contribution in the topics: Population & Dielectric. The organization has 11858 authors who have published 23917 publications receiving 464677 citations. The organization is also known as: Kashi Hindu Vishvavidyalay & Benares Hindu University.

Influence of Tempering on the Microstructure and Mechanical Properties of HSLA-100 Steel Plates

Abstract: The influence of tempering on the microstructure and mechanical properties of HSLA-100 steel (with C-0.04, Mn-0.87, Cu-1.77, Cr-0.58, Mo-0.57, Ni-3.54, and Nb-.038 pct) has been studied. The plate samples were tempered from 300 °C to 700 °C for 1 hour after austenitizing and water quenching. The transmission electron microscopy (TEM) studies of the as-quenched steel revealed a predominantly lath martensite structure along with fine precipitates of Cu and Nb(C, N). A very small amount of retained austenite could be seen in the lath boundaries in the quenched condition. Profuse precipitation of Cu could be noticed on tempering at 450 °C, which enhanced the strength of the steel significantly (yield strength (YS)—1168 MPa, and ultimate tensile strength (UTS)—1219 MPa), though at the cost of its notch toughness, which dropped to 37 and 14 J at 25 °C and −85 °C, respectively. The precipitates became considerably coarsened and elongated on tempering at 650 °C, resulting in a phenomenal rise in impact toughness (Charpy V-notch (CVN) of 196 and 149 J, respectively, at 25 °C and −85 °C) at the expense of YS and UTS. The best combination of strength and toughness has been obtained on tempering at 600 °C for 1 hour (YS-1015 MPa and UTS-1068 MPa, with 88 J at −85 °C).

An ab initio study of excited states of guanine in the gas phase and aqueous media: Electronic transitions and mechanism of spectral oscillations

Abstract: Ground state geometries of the four tautomeric forms keto-N9H, keto-N7H, enol-N9H, and enol-N7H of guanine were optimized in the gas phase at the RHF level using a mixed basis set consisting of the 4-31G basis set for all the atoms except the nitrogen atom of the amino group for which the 6-311+G* basis set was used. These calculations were also extended to hydrogen-bonded complexes of three water molecules with each of the keto-N9H (G9-3W) and keto-N7H (G7-3W) forms of guanine. Relative stabilities of the four above-mentioned tautomers of guanine as well as those of G9-3W and G7-3W complexes in the ground state in the gas phase were studied employing the MP2 correlation correction. In aqueous solution, relative stabilities of these systems were studied using the MP2 correlation correction and polarized continuum model (PCM) or the isodensity surface polarized continuum model (IPCM) of the self-consistent reaction field (SCRF) theory. Geometry optimization in the gas phase at the RHF level using the 6-31+G* basis set for all atoms and the solvation calculations in water at the MP2 level using the same basis set were also carried out for the nonplanar keto-N9H and keto-N7H forms of guanine. Thus, it is shown that among the different tautomers of guanine, the keto-N7H form is most stable in the gas phase, while the keto-N9H form is most stable in aqueous solution. It appears that both the keto-N9H and keto-N7H forms of guanine would be present in the ground state, particularly near the aqueous solution–air interface. Vertical excitation and excited state geometry optimization calculations were performed using configuration interaction involving single electron excitation (CIS). It is found that the absorption spectrum of guanine would arise mainly due to its keto-N9H form but the keto-N7H form of the same would also make some contribution to it. The enol-N9H and enol-N7H forms of the molecule are not expected to occur in appreciable abundance in the gas phase or aqueous media. The normal fluorescence spectrum of guanine in aqueous solution with a peak near 332 nm seems to originate from the lowest singlet excited state of the keto-N7H form of the molecule while the fluorescence of oxygen-rich aqueous solutions of guanine with a peak near 450 nm appears to originate from the lowest singlet excited state of the keto-N9H form of the molecule. The origin of the slow damped spectral oscillation observed in the absorption spectrum of guanine has been explained. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 826–846, 2000

Meconium stained amniotic fluid: antenatal, intrapartum and neonatal attributes.

Abstract: Objectives : To find out the incidence, outcome as well as antenatal, intrapartum and neonatal attributes of meconium stained amniotic fluid (MSAF). Design : Prospective study. Setting : Neonatal Unit of Hospital. Subjects : 1426 live births occurring in 1500 consecutive deliveries, over one year period. Interventions : In all babies born through MSAF, thorough oropharyngeal suction as soon as the head was delivered followed by immediate intratracheal intubation and suctioning in infants depressed at birth. Results : 204 (14.3%) deliveries had MSAF of which thick meconium was present in 141. Hepatitis in mother, fetal distress during labor and intrauterine growth retardation were significant factors associated with MSAF. One fifth of babies born through MSAF suffered severe birth anoxia compared to 5.6% in non-MSAF group. The consistency of meconium had direct bearing on the neonatal outcome. Severe birth asphyxia (SBA) occurred in 27.0 and 6.3% of babies with thick and thin meconium staining, respectively. Meconium aspiration syndrome was observed in 9 babies of thick meconium group and 8 of these were depressed at birth. All deaths occurred in thick meconium group and were associated with SBA. Conclusions : Selective approach can be adopted for babies with MSAF reserving intratracheal suctioning at birth for depressed neonate or evidence of fetal distress in utero. Rest of the neonates only need careful observation after thorough oronasopharyngeal suctioning.