Octane number enhancement studies of naphtha over noble metal loaded zeolite catalysts

An Indian industrial naphtha containing mixture of various hydrocarbons belong to n-paraffins, isoparaffins, naphthenes and aromatics falling in C₅ to C₉ carbon range has been studied for its octane boosting through the production of isoparaffins over various Pt loaded zeolite catalysts possessing different acidity and porosity properties. Optimum balance of acid and metal functionalities in 0.6 wt.% Pt loaded on BEA zeolite helped in achieving highest increase in research octane number (RON) from 44 to 80, suitable for gasoline applications, through the production of lower isoparaffins (iC₄-iC₆) along with C₇+ isoparaffins.     

High-temperature deformation behavior of NiAl(Ti) solid-solution single crystals

The high-temperature deformation behavior of the solid solution-strengthened alloys Ni-47.5Al-2.5Ti and Ni-47Al-3Ti were investigated. Single crystals were deformed in compression in the “hard” 〈001〉 and “soft” 〈111〉 orientations, at temperatures between 827 °C and 1250 °C. The results show that Ti has a very powerful solute-strengthening effect in NiAl. The creep rates for the solid-solution alloys were observed to be as much as three to four orders of magnitude lower than those for unalloyed NiAl. To better understand this strong solid-solution strengthening effect, we studied the stress and temperature dependence of the creep rates for these alloys, as well as the deformation transients associated with stress changes. These results suggest that solute-drag effects dominate the creep resistance at the highest temperatures and lowest stresses. The solute-drag hypothesis is supported by calculations of the solute-size effect of Ti in NiAl and by the form of dislocation substructures found in the creep-deformed crystals. W.D. NIX is the Lee Otterson Professor of Engineering with the Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305.     

Effect of non-active area on the performance of subgasketed MEAs in PEMFC

Subgaskets are usually applied to a catalyst-coated membrane (CCM) for the edge-protection of the electrolyte membrane and easy handling. They cover the peripheral region (non-active area) of CCM and have a defined window (active area) for accommodating the electrode. In this study, three subgasketed CCMs with different configurations were designed with a laboratory-scale 5 cm² fuel cell and the effects of the components underneath the subgaskets on the electrochemical properties of CCMs and cell performance were investigated by several electrochemical techniques. The results reveal that part of the catalyst layer under the subgaskets is activated for reaction area, leading to slightly higher electrochemical surface area (ESA), higher H₂ crossover, and smaller shorting resistance. The non-active region of subgasketed CCM has little impact on proton resistance in the catalyst layer, oxygen reduction reaction (ORR) kinetics, and limiting current, but has adverse effects on cell performance in the low current region under dry conditions due to increased hydrogen crossover. The findings could provide guidelines for subgasket design and application in laboratory-scale fuel cells.     

Development of a PCR assay for the detection of nifH and nifD genes in indigenous photosynthetic bacteria

Molybdenum (Mo) nitrogenases consist of two components: dinitrogenase reductase (encoded by nifH) and the dinitrogenase or MoFe protein (encoded by nifDK). Nitrogenase enzyme of photosynthetic bacteria is responsible for hydrogen production. Therefore, primers were designed for the nitrogenase gene only. In this study, two primers (ND and NH) were designed after comparative genomic analysis of nifH and nifD gene sequences from public databases. The designed primers were used for the amplification of nifH and nifD genes to detect nitrogenase genes in photosynthetic bacteria. Initial detection was done using a monoplex Polymerase Chain Reactions (PCRs) followed by optimization of the PCR protocols. Subsequently, a duplex PCR was designed for amplification and detection of nifH and nifD genes in indigenous photosynthetic bacteria. Evaluation of the duplex PCR on six samples isolated from Palm Oil Mill Effluent (POME) showed that only four isolates contained both the nifH and nifD genes, indicating that these isolates were potential hydrogen-producing bacteria. PCR detection provides a rapid and efficient pre-identification of potential photosynthetic bacterial hydrogen producers.     

Effects of stratification on chloramine decay in distribution system service reservoirs

Water quality in chloraminated distribution systems is affected by microbial activity, particularly due to nitrifiers that accelerate chloramine decay. In summer, continuous thermal stratification increases retention time and lowers chloramine residual in some parts of a system service reservoir (tank), relative to fully mixed conditions. According to temperature and chemical indicators, cooling in winter destratifies these reservoirs naturally. Traditional (chemical) indicators of nitrification also suggest that destratification occurs with respect to microbiological activity. In contrast, the microbial decay factor (F_m) method, which separates microbiological and chemical decay in bulk water, identifies strong microbial stratification, even in winter. F_m can also be used to predict the exacerbated loss of chloramine residual in the following summer, which enables early intervention by system managers to minimise such loss, and so maintain an adequate residual through the distribution system.     

Electricity generation from rice husk in Indian rice mills: potential and financial viability

Rice husk generated as a by-product of rice processing is an important energy resource. The availability of this resource in India has been assessed and the technologies for exploitation of its energy potential in rice processing industry discussed. Nomographs have been developed for estimation of the husk required to meet the energy demand of parboiling, drying and milling operations. The unit cost of electricity using rice husk gasifier-based power generation systems has been calculated and its financial feasibility assessed in comparison with utility-supplied and diesel-generated electricity. With the cost and efficiency data assumed here, the unit cost of electricity produced by rice husk gasifier-dual fuel engine-generator system varies between Rs 2/kWh and Rs 7/kWh. (Note: 35 Rs approximates to $US 1.)     

Transient solutions of a software reliability model with imperfect debugging and error generation

In this paper we obtain transient solutions of a software reliability model under the assumption that the failure rate is proportional to the remaining errors in the software under imperfect debugging and error generation. The maximum number of errors in the software is assumed to be finite. We obtain the transient probabilities for the remaining errors, mean number of errors remaining, reliability of the software, expected number of failures etc. A method to estimate model parameters is given. Finally, a numerical example is presented.     

Time-dependent queueing model having heterogeneous servers

The present paper considers a time-dependent queueing model having a finite number of parallel channels each having a different service rate. The probabilities of the exact number of arrivals and departures by a given time and marginal probabilities of the exact number of arrivals are obtained.     

Ca(2+)-ATPases in the cochlear duct

Differing levels of the Ca(2+)-ATPase enzymes that reside on the plasma membrane (PM) and on the endoplasmic reticulum (ER) were identified in individual rat cochlear tissues by the use of a semi-quantitative enzyme-linked immunosorbent assay (ELISA). Unlike other studies, a specific antibody to PM Ca(2+)-ATPase was used to detect significantly greater levels (about 2x) of PM Ca(2+)-ATPase in the stria vascularis (SV) than that in the spiral ligament (SL) and organ of Corti (OC) tissues. Similarly, levels of ER Ca(2+)-ATPase were also significantly higher in the SV than in the SL and OC tissues. The presence of ER Ca(2+)-ATPase in the tissues of the SV has not been demonstrated previously. Given the importance of Ca2+ homeostasis in the inner ear, the statistically significantly higher densities of both PM and ER Ca(2+)-ATPase measured in the SV relative to the SL and OC regions would indicate tissue-specific responses to fluctuations in systemic and local Ca2+ concentrations.