Aerosol characteristics and radiative impacts over the Arabian Sea during the intermonsoon season: Results from ARMEX field campaign

During the second phase of the Arabian Sea Monsoon Experiment (ARMEX-II), extensive measurements of spectral aerosol optical depth, mass concentration, and mass size distribution of ambient aerosols as well as mass concentration of aerosol black carbon (BC) were made onboard a research vessel during the intermonsoon period (i.e., when the monsoon winds are in transition from northeasterlies to westerlies/ southwesterlies) over the Arabian Sea (AS) adjoining the Indian Peninsula. Simultaneous measurements of spectral aerosol optical depths (AODs) were made at different regions over the adjoining Indian landmass. Mean AODs (at 500-nm wavelength) over the ocean (similar to0.44) were comparable to those over the coastal land (similar to0.47), but were lower than the values observed over the plateau regions of central Indian Peninsula (similar to0.61). The aerosol properties were found to respond distinctly with respect to change in the trajectories, with higher optical depths and flatter AOD spectra associated with trajectories indicating advection from west Asia, and northwest and west-coastal India. On average, BC constituted only similar to2.2% to total aerosol mass compared to the climatological values of similar to6% over the coastal land during the same season. These data are used to characterize the physical properties of aerosols and to assess the resulting short-wave direct aerosol forcing. The mean values were similar to27 W m(-2) at the surface and -12 W m(-2) at the top of the atmosphere (TOA), resulting in a net atmospheric forcing of +15 W m(-2). The forcing also depended on the region from where the advection predominates. The surface and atmospheric forcing were in the range -40 to -57 W m(-2) and +27 to +39 W m(-2), respectively, corresponding to advection from the west Asian and western coastal India where they were as low as -19 and +10 W m(-2), respectively, when the advection was mainly from the Bay of Bengal and from central/peninsular India. In all these cases, the net atmospheric forcing (heating) efficiency was lower than the values reported for northern Indian Ocean during northern winter, which is attributed to the reduced BC mass fraction.

Improved k-t BLAST for fast fMR imaging

A popular dynamic imaging technique, k-t BLAST (ktB) is studied here for BAR imaging. ktB utilizes correlations in k-space and time, to reconstruct the image time series with only a fraction of the data. The algorithm works by unwrapping the aliased Fourier conjugate space of k-t (y-f-space). The unwrapping process utilizes the estimate of the true y-f-space, by acquiring densely sampled low k-space data. The drawbacks of this method include separate training scan, blurred training estimates and aliased phase maps. The proposed changes are incorporation of phase information from the training map and using generalized-series-extrapolated training map. The proposed technique is compared with ktB on real fMRI data. The proposed changes allow for ktB to operate at an acceleration factor of 6. Performance is evaluated by comparing activation maps obtained using reconstructed images. An improvement of up to 10 dB is observed in thePSNR of activation maps. Besides, a 10% reduction in RMSE is obtained over the entire time series of fMRI images. Peak improvement of the proposed method over ktB is 35%, averaged over five data sets. (C)2010 Elsevier Inc. All rights reserved.

Resistometric studies of solute-vacancy interactions and clustering kinetics in an FCC matrix [AlZn Alloy with Ag, Ce, Dy, Li, Nb, Pt, Sb, Y, or Yb]

Al-4.4 a/oZn and Al-4.4 a/oZn with Ag, Ce, Dy, Li, Nb, Pt, Y, or Yb, alloys have been investigated by resistometry with a view to study the solute-vacancy interactions and clustering kinetics in these alloys. Solute-vacancy binding energies have been evaluated for all these elements by making use of appropriate methods of evaluation. Ag and Dy additions yield some interesting results and these have been discussed in the thesis. Solute-vacancy binding energy values obtained here have been compared with other available values and discussed. A study of the type of interaction between vacancies and solute atoms indicates that the valency effect is more predominant than the elastic effect.

Investigations of superconducting bismuth cuprates of the general formula Bi2-xPbx(Ca,Sr,Y)n 1 Cun O2n 4 δ

In the (Bi,Pb)-Sr-Cu-O system we have examined many compositions which are either metallic or semiconducting. In the Bi2-xPbx(Ca, Sr)n+1 Cun O2n+4+δ system, we have established the superconducting properties of the n = 1 to 4 members. The Tc increases from n = 1 to 3 and does not increase further when n = 4. In Bi2Ca1-x,YxSr2Cu2Oy, the Tc decreases with increase in x.

Aspects of tautomerism. Part 16. Influence of the y-keto function on the reactions of sulphonic acids

Reaction of sodium 2-formylbenzenesulphonate (1) with thionyl chloride or phosphorous pentachloride gives a mixture of pseudo (2) and normal (3) sulphonyl chlorides. Whereas ammonium 2-carboxybenzenesulphonate (6) gives only the normal sulphonyl chloride (7) on reaction with thionyl chloride, a mixture of normal (7) and pseudo (8) isomers are formed on reaction with phosphorous pentachloride. Sodium 2-benzoylbenzenesulphonate (15), on the other hand, gives the corresponding normal sulphonyl chloride (16) on reaction with both of the reagents mentioned above. Based on these observations it is concluded that γ-keto sulphonic acids are amenable to the influence of γ-carbonyl group as in the case of γ-keto carboxylic acids but to a lesser extent. © 1989 Indian Academy of Sciences.

Enhancement of workability in AZ31 alloy-processing maps: Part I,castmaterial

Processing maps developed on the basis of the Dynamic Materials Model provide valuable information that might help the metal working industry in solving problems related to workability and microstructural control in commercial alloys. In this research, the processing maps for an as-cast AZ31 magnesium alloy are presented. The results are validated via microstructural observations, clearly delineating safe and unsafe regimes for further process design of this alloy.

Rare earth exchanged (Ce3+, La3+ and RE3+) H-Y zeolites as solid acid catalysts for the synthesis of linear alkyl benzenes

Rare earth exchanged H–Y zeolites were prepared by simple ion exchange methods at 353 K and have been characterized using different physicochemical techniques. A strong peak around 58 ppm in the 27Al{1H} MAS NMR spectra of these zeolites suggests a tetrahedral coordination for the framework aluminium. Small peak at or near 0 ppm is due to hexa-coordinated extra-framework aluminium and a shoulder peak near 30 ppm is a penta-coordinated aluminium species; [Al(OH)4]−. The vapor-phase benzene alkylation with 1-decene and 1-dodecene was investigated with these catalytic systems. Under the reaction conditions of 448 K, benzene/olefin molar ratio of 20 and time on stream 3 h, the most efficient catalyst was CeH–Y which showed more than 70% of olefin conversion with 48.5% 2-phenyldecane and 46.8%, 2-phenyldodecane selectivities with 1-decene and 1-dodecene respectively.

Magnetism of Ti4+ diluted manganites La1-xPbxMn1-yTiyO3 (y <= x)

The effect of nonmagnetic Ti4+ substitution for Mn4+ on magnetic ordering of La1-xPbxMn1-yTiyO3 (x = 0.15,0.26, and 0.4; 0 less than or equal to y less than or equal to x )has been studied. The ferromagnetic transition temperature and the magnetization decrease with increasing amount of titanium. Complete substitution of Mn4+ by Ti4+, for x = y, excludes the Mn3+-O-Mn4+ double exchange. However, these compounds still show ferromagnetism if the dilution of the Mn sublattice by Ti is small enough (y less than or equal to 0.2). This ferromagnetism probably originates from a ferromagnetic Mn3+-O-Mn3+ superexchange. A thorough study of magnetic properties including AC magnetic susceptibility, magnetization, temperature dependence of coercivity and relaxation of remanent magnetization has been carried out and gives evidence of cluster spin glass behaviour for La0.6Pb0.4Mn0.6Ti0.4O3. (C) 2000 Elsevier Science B.V. All rights reserved.

A series of metallic oxides of the formula La3LnBaCu5O13+δ (Ln = rare earth or Y)

Oxides of the formula La3LnBaCu5O13+δ (Ln = Nd, Sm, Gd, Dy, or Y) exhibiting metallic resistivity have been prepared and characterized. In the case of yttrium, a composition close to La2Y2BaCu5O13+δ, which is also metallic, could be prepared.

On superconducting Y-Ba-Cu-O films prepared by printing on lumina substrates

This Letter attempts to examine the impact of the chemical interaction of the alumina substrate on the Y-Ba-Cu-O film deposited on it.

Towards a green synthesis of LAB's: Effect of rare earth metal ions on the benzene alkylation with 1-dodecene over NaFAU-Y zeolites

Chemically modified microporous materials can be prepared as robust catalysts suitable for application in vapor phase processes such as Friedel-Crafts alkylation. In the present paper we have investigated the use of rare earth metal (Ce3+, La3+, RE3+, and Sm3+) exchanged Na-Y zeolites as catalysts for the alkylation of benzene with long chain linear 1-olefin; 1-dodecene. Thermodesorption studies of 2,6-dimethylpyridine adsorbed catalysts (in the temperature range 573 to 873 K) show that the rare earth zeolites are highly Bronsted acidic in nature. A perfect correlation between catalyst selectivity towards the desired product (2-phenyldodecane) and Bronsted acid sites amount has been observed. (c) 2006 Springer Science + Business Media, Inc.

Design and fabrication of an automated temperature programmed reaction system to evaluate 3-way catalysts Ce1-x-y(La/Y)(x)PtyO2-delta

A completely automated temperature-programmed reaction (TPR) system for carrying out gas-solid catalytic reactions under atmospheric flow conditions is fabricated to study CO and hydrocarbon oxidation, and NO reduction. The system consists of an all-stainless steel UHV system, quadrupole mass spectrometer SX200 (VG Scientific), a tubular furnace and micro-reactor, a temperature controller, a versatile gas handling system, and a data acquisition and analysis system. The performance of the system has been tested under standard experimental conditions for CO oxidation over well-characterized Ce1-x-y(La/Y)(y)O2-delta catalysts. Testing of 3-way catalysis with CO, NO and C2H2 to convert to CO2, N-2 and H2O is done with this catalyst which shows complete removal of pollutants below 325 degrees C. Fixed oxide-ion defects in Pt substituted Ce1-y(La/Y)(y)O2-y/2 show higher catalytic activity than Pt ion-substituted CeO2

High temperature deformation processing maps for boron modified Ti-6Al-4V alloys

The alloy, Ti-6Al-4V is an alpha + beta Ti alloy that has large prior beta grain size (similar to 2 mm) in the as cast state. Minor addition of B (about 0.1 wt.%) to it refines the grain size significantly as well as produces in-situ TiB needles. The role played by these microstructural modifications on high temperature deformation processing maps of B-modified Ti64 alloys is examined in this paper.Power dissipation efficiency and instability maps have been generated within the temperature range of 750-1000 degrees C and strain rate range of 10(-3)-10(+1) s(-1). Various deformation mechanisms, which operate in different temperature-strain rate regimes, were identified with the aid of the maps and complementary microstructural analysis of the deformed specimens. Results indicate four distinct deformation domains within the range of experimental conditions examined, with the combination of 900-1000 degrees C and 10(-3)-10(-2) s(-1) being the optimum for hot working. In that zone, dynamic globularization of alpha laths is the principle deformation mechanism. The marked reduction in the prior beta grain size, achieved with the addition of B, does not appear to alter this domain markedly. The other domains, with negative values of instability parameter, show undesirable microstructural features such as extensive kinking/bending of alpha laths and breaking of beta laths for Ti64-0.0B as well as generation of voids and cracks in the matrix and TiB needles in the B-modified alloys. (C) 2010 Elsevier B.V. All rights reserved.

Constructing Reeb Graphs using Cylinder Maps

The Reeb graph of a scalar function represents the evolution of the topology of its level sets. In this video, we describe a near-optimal output-sensitive algorithm for computing the Reeb graph of scalar functions defined over manifolds. Key to the simplicity and efficiency of the algorithm is an alternate definition of the Reeb graph that considers equivalence classes of level sets instead of individual level sets. The algorithm works in two steps. The first step locates all critical points of the function in the domain. Arcs in the Reeb graph are computed in the second step using a simple search procedure that works on a small subset of the domain that corresponds to a pair of critical points. The algorithm is also able to handle non-manifold domains.

Design and fabrication of an automated temperature programmed reaction system to evaluate 3-way catalysts Ce1-x-y(La/Y)(x)PtyO2-delta

A completely automated temperature-programmed reaction (TPR) system for carrying out gas-solid catalytic reactions under atmospheric flow conditions is fabricated to study CO and hydrocarbon oxidation, and NO reduction. The system consists of an all-stainless steel UHV system, quadrupole mass spectrometer SX200 (VG Scientific), a tubular furnace and micro-reactor, a temperature controller, a versatile gas handling system, and a data acquisition and analysis system. The performance of the system has been tested under standard experimental conditions for CO oxidation over well-characterized Ce1-x-y(La/Y)(y)O2-delta catalysts. Testing of 3-way catalysis with CO, NO and C2H2 to convert to CO2, N-2 and H2O is done with this catalyst which shows complete removal of pollutants below 325 degrees C. Fixed oxide-ion defects in Pt substituted Ce1-y(La/Y)(y)O2-y/2 show higher catalytic activity than Pt ion-substituted CeO2.