An improved algorithm for connectivity analysis of distribution networks

In the present paper, an efficient algorithm for connectivity analysis of moderately sized distribution networks has been suggested. Algorithm is based on generation of all possible minimal system cutsets. The algorithm is efficient as it identifies only the necessary and sufficient conditions of system failure conditions in n-out-of-n type of distribution networks. The proposed algorithm is demonstrated with the help of saturated and unsaturated distribution networks. The computational efficiency of the algorithm is justified by comparing the computational efforts with the previously suggested appended spanning tree (AST) algorithm. The proposed technique has the added advantage as it can be utilized for generation of system inequalities which is useful in reliability estimation of capacitated networks.     

Improved field emission from multiwall carbon nanotubes with nano-size defects produced by ultra-low energy ion bombardment

Multiwalled carbon nanotubes were irradiated with ultra-low energy (few eV) nitrogen and hydrogen ions using a microwave discharge. These ultra-low energy plasma-ions remain confined to the nanotube walls, transferring their maximum energy to the carbon atoms, and produce extraordinary structural changes to the carbon nanotube pillars as well as within the carbon nanotubes. Conical shaped emitters and nanotube structures with nano-defects are produced that exhibit remarkable field emission with ultra-low turn-on electric field (∼0.16 V/μm) and a >300-fold increase in the maximum emission current density compared to non-irradiated nanotubes. Doping of nitrogen is also identified due to such irradiation processes.     

Correlation between structural properties and gas sensing characteristics of SnO2 based gas sensors

Undoped polycrystalline tin oxide sintered in the temperature range 500–1000 °C has been comprehensively characterized with respect to its response to CO, methane and H₂. Results obtained at an operating temperature of 300 °C show that increasing the sintering temperature leads to a gradual increase in CO sensitivity which reaches a maximum after sintering at 800 °C.     

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.     

Phase equilibria calculations of Al---In and Al---In---Sb systems

Thermodynamic properties of the liquid phases in Al-In and Al-In-Sb systems have been assessed by using quasi sub-subregular solution model and (Al_yIn_1−y) Sb phase in the Al-In-Sb system is considered as a regular solid solution of AlSb and InSb compounds. Thermodynamic properties and phase diagrams of these systems calculated by using the optimised model parameters agree well with the available experimental data.     

Thermopower of YBa2Cu3O7-δ–Ag Composites

The percolation behavior of normal-state thermopower, resistivity, and superconductivity have been studied in YBa₂Cu₃O_7-δ─Ag (YBCO─Ag) composite systems. The normal-state resistivity and thermopower show a percolation threshold at a Ag volume fraction ( V _Ag) of 20% to 30%, whereas the superconducting network shows a threshold at a V _Ag of ≅70% to 80%. The results obtained from this study show that the YBCO─Ag composite obtained from Ag₂O and YBCO powders is uniformly distributed with Ag and YBCO remaining as separate phases without changing their characteristics. The measurements of thermopower indicate that the normal-state thermopower and phonon-drag thermopower are affected by the Ag addition. The stability of YBCO is increased when it is in composite form.     

EXTRACTIVE DISTILLATION WITH AQUEOUS SOLUTIONS OF HYDROTROPES

The effect of hydrotropes on vapor-liquid equilibrium of a mixture provides a potential technique of extractive distillation for systems which are difficult or impossible to separate by normal rectification. Various hydrotropes, such as sodium toluate, sodium toluence sulfonate, sodium cymcnc sulfonate, sodium mesitylene sulfonate and sodium salicylate, in aqueous solutions have been tested for the separation of close-boiling point mixtures, such as p-cresol/2,6-xylenol, isopropanol/ fm-butanol, and wc-butanol/rert-butanol. The changes in the relative volatility increase with the concentration of hydrotrope and with the hydrotrope to solute ratio.