Optical Spectroscopy of Type Ia Supernovae

We present 432 low-dispersion optical spectra of 32 Type Ia supernovae (SNe Ia) that also have well-calibrated light curves. The coverage ranges from 6 epochs to 36 epochs of spectroscopy. Most of the data were obtained with the 1.5m Tillinghast telescope at the F. L. Whipple Observatory with typical wavelength coverage of 3700-7400A and a resolution of ~7A. The earliest spectra are thirteen days before B-band maximum; two-thirds of the SNe were observed before maximum brightness. Coverage for some SNe continues almost to the nebular phase. The consistency of the method of observation and the technique of reduction makes this an ideal data set for studying the spectroscopic diversity of SNe Ia.Comment: Accepted for publication in the Astronomical Journal, 109 pages (including data table), 44 figures, full resolution figures at http://www.noao.edu/noao/staff/matheson/Iaspec.ps.g

Superposition of DC voltage and submicrosecond impulses for energization of electrostatic precipitators

This paper discusses the development of an impulsive microelectrostatic precipitation technology, which uses superposition of submicrosecond high-field pulses and dc electric field. Short impulses allow the application of higher voltages to the ionization electrodes of a precipitation system without the initiation of breakdown. These higher levels of electric field generate higher ionic concentrations, resulting in more efficient charging of the airborne particles, and can potentially improve precipitation efficiency. This work is focused on the analysis of the behavior of impulsive positive corona discharges in a coaxial reactor designed for precipitation studies. The efficiency of precipitation of coarse and fine particles has been investigated using different dc and impulse voltage levels in order to establish optimal energization modes

Fundamental studies on the synthesis of heat-resistant polymers Summary report no. 12, 31 Jan. - 15 Sep. 1966

Synthesis and thermogravimetric analysis of heat resistant polymer

Iridoid glucosides from Pentas lanceolata (Forssk.) Deflers growing on the Island of Sardinia

The ethanolic extract of Pentas lanceolata (Forssk.) Deflers was investigated from a phytochemical point of view and in particular on the monoterpenoid glucosides content. Iridoid glucosides have a taxonomic relevance, e.g., asperuloside and its derivative are characteristic of the Rubioideae subfamily where this species is comprised. In the light of earliest phylogenetic molecular study which proposed to merge P. lanceolata in the Spermacoceae tribe, a phytochemical approach also becomes necessary for a correct classification of this species. A total of 12 compounds were identified in detail, ten of these are iridoid glucosides: asperuloside, asperulosidic acid, tudoside, E-uenfoside and Z-uenfoside previously identified in this genus; whereas, deacetyl-asperulosidic acid, ixoside, griselinoside, 6β,7β-epoxysplendoside were recognized here for the first time from P. lanceolata. Among the non-iridoidic compounds ursolic acid and d-xylose were identified

The direct synthesis of crosslinked polymeric azomethines

Char yields of synthesized crosslinked polymeric azomethine

High-energy Particle Acceleration and Production of Ultra-high-energy Cosmic Rays in the Giant Lobes of Centaurus A

‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2008.14265.xThe nearby radio galaxy Centaurus A is poorly studied at high frequencies with conventional radio telescopes because of its very large angular size, but is one of a very few extragalactic objects to be detected and resolved by the Wilkinson Microwave Anisotropy Probe (WMAP).We have used the five-year WMAP data for Cen A to constrain the high-frequency radio spectra of the 10-degree giant lobes and to search for spectral changes as a function of position along the lobes. We show that the high-frequency radio spectra of the northern and southern giant lobes are significantly different: the spectrum of the southern lobe steepens monotonically (and is steeper further from the active nucleus) whereas the spectrum of the northern lobe remains consistent with a power law. The inferred differences in the northern and southern giant lobes may be the result of real differences in their high-energy particle acceleration histories, perhaps due to the influence of the northern middle lobe, an intermediate-scale feature which has no detectable southern counterpart. In light of these results, we discuss the prospects for Gamma-ray Large Area Space Telescope (GLAST) detections of inverse-Compton emission from the giant lobes and the lobes’ possible role in the production of the ultra-high energy cosmic rays (UHECR) detected by the Pierre Auger Observatory. We show that the possibility of a GLAST detection depends sensitively on the physical conditions in the giant lobes, with the northern lobe more likely to be detected, and that any emission observed by GLAST is likely to be restricted to the soft end of the GLAST energy band. On the other hand we argue that the estimated conditions in the giant lobes imply that UHECRs can be accelerated there, with a potentially detectable -ray signature at GeV-TeV energies.Peer reviewe

Plastisol Foaming Process. Decomposition of the Foaming Agent, Polymer Behavior in the Corresponding Temperature Range and Resulting Foam Properties

The decomposition of azodicarbonamide, used as foaming agent in PVC - plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min-1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g -1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol-1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse

Polymeric Schiff bases. 17 - Azomethine copolymers

Chemical synthesis of azomethine copolymers by melt polymerization techniques - polymeric Schiff base

Stubble rice (Oryza sativa L.) in direct sowing systems : handling alternatives

Los objetivos principales del presente trabajo fueron: a) Estudiar cuál es el uso adecuado de las distintas herramientas para mejorar la mineralización del rastrojo de la cosecha de arroz (Oryza sativa L.) bajo siembra directa y b) Determinar, para períodos cortos, la cantidad de rastrojo depositado superficialmente y su tiempo de mineralización al utilizar las distintas técnicas de manejo del mismo. Los tratamientos fueron: cosechadora con desparramador deflector (T1DD), cosechadora sin desparramador triturador (T2SDT), cosechadora con desparramador centrífugo de caucho (T3DC) y cosechadora con desparramador metálico (T4DM). Alternativas implementadas: a) desmalezado b) rolo cuchilla y c) quemado de rastrojo. En las primeras dos alternativas, se aplicaron tres dosis de urea. Los resultados principales fueron: a) La T2SDT produjo, una mayor deposición de material en el centro de la máquina (21680 kg ha-1), b) la distribución de rastrojo de la (T3DC) fue más uniforme que para los otros tratamientos. Las principales conclusiones fueron: 1) Los desparramadores centrífugos de caucho y metálico produjeron mejor distribución del material, 2) El uso de desmalezadora o rolo cuchilla sobre rastrojo de los tratamientos T3DC y T4DM aceleró la mineralización de los mismos. 3) Las dosis de urea causó poco incremento en la mineralización del rastrojo.The main purposes of this study were to: a) Find out how tools (deflectors, spreaders and choppers) can be used best for improving mineralization of stubble from harvesting rice (Oryza sativa L.) grown under direct sowing and b) Determine, for short periods, the amount of crop residues deposited on the surface and its mineralization time with various management techniques. The treatments were: harvester with spreader (T1DD), harvester without spreader (T2SDT), harvester with rubber centrifugal spreader (T3DC) and harvester with metal spreader (T4DM). Implemented alternatives: a) rotary weed cutter b) blade roller and c) burning crop residues. In the first two alternatives, three doses of urea were applied. The main results were: a) The harvester without spreader (T2SDT) deposited more material in the center of the tail (21680 kg ha-1), b) when distribution of crop residues from the (T3DC) was more uniform compared with the other treatments. The main conclusions were: 1) the rubber centrifugal spreader and metal spreader produced better distribution of the stubble, 2) The use of rotary weed cutter or blade roller on stubble distributed by harvesters T3DC and T4DM treatments caused accelerated mineralization of the same, 3) Urea doses caused little increase in mineralization of the rice stubble.Fil: Hidalgo, Ramón J.. Universidad Nacional del Nordeste. Facultad de Ciencias AgrariasFil: Botta, Guido Fernando. Universidad Nacional de LujánFil: Tolón Becerra, Alfredo. Universidad de AlmeríaFil: Pozzolo, Oscar R.. Instituto Nacional de Tecnología Agropecuaria (Argentina). Centro Nacional de Investigaciones Agropecuarias. Complejo CastelarFil: Dominguez, José F.. Universidad Nacional del NordesteFil: Serafini, Emiliano. Universidad Nacional del Nordest

Suzuki reaction on pyridinium N-haloheteroarylaminides: regioselective synthesis of 3,5-disubstituted 2-aminopyrazines

An extensive study of Suzuki–Miyaura cross-coupling processes on N-pyridinium bromoazinyl aminides has been performed. Mono- and disubstitution on 5- and 3,5-bromo derivatives produced the corresponding aryl derivatives. In the disubstituted compounds regioselective substitution at the 3-position occurred, vicinal to the aminide nitrogen, and this was more evident in pyrazine derivatives. The commonly used strategy involving N-alkylation and reduction of the N–N bond gave rise to a series of 2-alkylamino-3,5-disubstituted-pyrazines.The authors wish to thank the Comisión Interministerial de Ciencia y Tecnología (CICYT-BQU2001-1508 and CTQ2005-08902) and the Universidad de Alcalá (UAH GC2005/006) for financial support and the Ministerio de Educación y Ciencia (MEC) for two studentships (M.J.R. and R.C.). We also thank Professor Mijail Galajov for his assistance in the NMR study