Space Complexity of Perfect Matching in Bounded Genus Bipartite Graphs

We investigate the space complexity of certain perfect matching problems over bipartite graphs embedded on surfaces of constant genus (orientable or non-orientable). We show that the problems of deciding whether such graphs have (1) a perfect matching or not and (2) a unique perfect matching or not, are in the logspace complexity class \SPL. Since \SPL\ is contained in the logspace counting classes \oplus\L (in fact in \modk\ for all $k\geq 2$), \CeqL, and \PL, our upper bound places the above-mentioned matching problems in these counting classes as well. We also show that the search version, computing a perfect matching, for this class of graphs is in \FL^{\SPL}. Our results extend the same upper bounds for these problems over bipartite planar graphs known earlier. As our main technical result, we design a logspace computable and polynomially bounded weight function which isolates a minimum weight perfect matching in bipartite graphs embedded on surfaces of constant genus. We use results from algebraic topology for proving the correctness of the weight function.Comment: 23 pages, 13 figure

Fluidised Bed Heat Treatment - A Flexible Heat Treating Technology

For heat treatment of metal parts wide variety of furnaces are employed. Protective atmosphere furnaces like sealed quench furnace, vaccum furnaces, pit type retort, rotary retort furnaces and salt bath furnaces are used for heat treatment processes. In recent years flui-dised bed furnaces are gaining popularity due to certain inherent advantages associated with them. Almost all the processes such as neutral hardening, carburising, carbon-itriding, annealing, nitriding nitrocarburising etc. can be carried out with a single fluidised bed furnace inst-allation. Added to this flexibility bed temperature uni-formity, quick change over of atmospheres, fast rate of heat transfer and bed buoyancy results in predictable and consistent results in properties and dimensions after heat treatment

'Ossification'- a novel approach for immobilisation of platinum group metal complex catalysts

The technique known as 'ossification' has emerged as one of the most promising approaches for immobilisation of metal complexes, generating highly selective, stable and recyclable heterogeneous counterparts of homogeneous catalysts. 'Ossification' involves modifying the ligand(s) in a metal complex catalyst to achieve inherently insoluble forms of the metal complexes, without destroying the configuration responsible for their catalytic properties. The ossified catalysts have been demonstrated to show high catalytic activity and selectivity for a number of industrially important reaction classes such as palladium-catalysed carbonylation and Suzuki coupling and rhodium-catalysed hydroformylation. The characterisation of these catalysts has also shown that the key features of their homogeneous metal complex analogues are retained on immobilisation. The approach is very useful for the design and development of immobilised catalysts with specific features and functionality for various applications. It is also advantageous for catalyst-product separation. This article reviews the recent work on ossification involving platinum group metal complex catalysts in our research group

PC Controlled Rain Simulation

Rainfall simulators have a long history of successful use in both laboratory and field investigations. A challenge faced today is to have practical method of assessing the impact of various natural phenomena on day to day life. With the climatic change taking place globally, there is necessity to simulate rain to assess and estimate its impact on our lives. It is developed with an objective to simulate rainfall which is computer controlled hardware implemented simulation for scaled model food godown. In this paper, we describe simulation of rain practically on a scaled model. The simulator is controlled by PC which can be programmed as per the requirement of user and can be modified and adopted easily. The process of PWM is achieved using a PC which has custom developed program interfaced to drive a water delivery system through PLC and MOSFET drive. DOI: 10.17762/ijritcc2321-8169.15064

Rh-Catalyzed Hydroformylation of 1,3-Butadiene and Pent-4-enal to Adipaldehyde in CO2-Expanded Media

The homogeneous hydroformylation of pent-4-enal, the preferred aldehyde intermediate from 1,3-butadiene hydroformylation, was systematically investigated with Rh catalyst complexes in neat and CO2-expanded toluene media at 40–80 °C, syngas partial pressures ranging from 5–50 bar, and different ligand/Rh ratios. At similar operating conditions, the TOFs are generally greater with Rh/DIOP relative to a Rh/TPP catalyst. On both catalyst complexes, the chemoselectivity toward the dialdehydes ranges from 75%–100%, with the maximum adipaldehyde selectivity reaching approximately 75% (n/i ∼ 3) at 60 °C, 10 bar syngas, and molar DIOP/Rh ratio of 2.5. By using CO2-expanded toluene, the regioselectivity toward the adipaldehyde (desired product), and therefore its yield, is significantly enhanced. Interestingly, even with the simple Rh/TPP catalyst complex, adipaldehyde selectivity of up to 85% (n/i ∼ 5.6) is achieved at 60 °C, 10 bar syngas, and 50 bar CO2. The beneficial effects of CO2-expanded media are attributed to the facile tunability of the H2/CO ratio in such a phase with a fixed syngas feed composition. This approach to accelerate pent-4-enal hydroformylation to form adipaldehyde could also help in overcoming equilibrium limitations typically associated with the catalytic isomerization of pent-3-enal (the dominant product from 1,3-butadiene hydroformylation) to pent-4-enal (the preferred isomer)

A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O₂ airglow temperatures measurements

The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation

Liquid-Phase Oxidation of Ethylene Glycol on Pt and Pt–Fe Catalysts for the Production of Glycolic Acid: Remarkable Bimetallic Effect and Reaction Mechanism

A highly active and selective Pt–Fe alloy catalyst on CeO2 support is reported in this work for aqueous phase oxidation of ethylene glycol (EG) to glycolic acid. The Pt–Fe nanoparticles are highly alloyed with a face-centered cubic (fcc) type of crystal structure and a chemical state of Pt0/Fe0, as confirmed from X-ray diffraction and extended X-ray absorption fine structure characterizations, respectively. Compared to the monometallic Pt catalyst, the Pt–Fe catalyst shows more than a 17-fold higher initial TOF, while achieving complete EG conversion in 4 h at 70 °C and ambient O2 pressure under alkaline conditions. The synergistic bimetallic effect occurs due to significantly changing the O2 adsorption-dissociation characteristics on the catalyst surface. The addition of a base shows a promotional effect on both Pt and Pt–Fe catalysts at low NaOH concentrations but an inhibition effect is observed for both catalysts at sufficiently high NaOH concentrations. Furthermore, the base enhances the synergistic effect observed with Pt–Fe catalyst

Rectovestibular fistula: Is treatment always required?

The traditional teaching in the management of rectovestibular fistula involves corrective surgery, either in single or multiple stages.Usually, female children operated for the same are advised cesarean section during childbirth to prevent damage to the neoanus.Herein, we report a story of a 68-year-old woman with untreated rectovestibular fistula and has given birth to five children withoutany sequalae