Polymerization of the E and Z Isomers of Bis-(Triethoxysilyl)-2-Butene

We have synthesized the Z and E isomers of 1,4-bis(triethoxysilyl)-2- butene and polymerized them under acid and base catalyzed sol-gel conditions. As expected the E system formed crosslinked, insoluble gels. The Z isomer, by nature of its geometry, formed high molecular weight, soluble polymeric products under acidic conditions. We were able to prepare and isolate both the cyclic disilsesquioxane monomer, and its dimer. Comparison of their spectral characterization with that of the soluble polymers suggests that the cyclics are present within the polymers. lle synthesis of a dimer likely present at some early stage of the polymerization suggests that we may be able to control the reaction and form rigid polymers with controllable tacticity. In addition, most of the gels were found to be non-porous indicating that the gels were, in fact, more compliant than ethenylene-bridged polysilsesquioxanes leading to collapse of pores during drying

Diagnostic applications of molecular and serological assays for bluetongue and African horse sickness

The availability of rapid, highly sensitive and specific molecular and serologic diagnostic assays, such as competitive enzyme-linked immunosorbent assay (cELISA), has expedited the diagnosis of emerging transboundary animal diseases, including bluetongue (BT) and African horse sickness (AHS), and facilitated more thorough characterisation of their epidemiology. The development of assays based on real-time, reverse-transcription polymerase chain reaction (RT-PCR) to detect and identify the numerous serotypes of BT virus (BTV) and AHS virus (AHSV) has aided in-depth studies of the epidemiology of BTV infection in California and AHSV infection in South Africa. The subsequent evaluation of pan-serotype, real-time, RT-PCR-positive samples through the use of serotype-specific RT-PCR assays allows the rapid identification of virus serotypes, reducing the need for expensive and time-consuming conventional methods, such as virus isolation and serotype-specific virus neutralisation assays. These molecular assays and cELISA platforms provide tools that have enhanced epidemiologic surveillance strategies and improved our understanding of potentially altered Culicoides midge behaviour when infected with BTV. They have also supported the detection of subclinical AHSV infection of vaccinated horses in South Africa. Moreover, in conjunction with whole genome sequence analysis, these tests have clarified that the mechanism behind recent outbreaks of AHS in the AHS-controlled area of South Africa was the result of the reversion to virulence and/or genome reassortment of live attenuated vaccine viruses. This review focuses on the use of contemporary molecular diagnostic assays in the context of recent epidemiologic studies and explores their advantages over historic virus isolation and serologic techniques.https://www.woah.org/en/what-we-do/publications/scientific-and-technical-reviewVeterinary Tropical Disease

Neonatal Genetic Variation in Steroid Metabolism and Key Respiratory Function Genes and Perinatal Outcomes in Single and Multiple Courses of Corticosteroids

To evaluate the association of steroid metabolism and respiratory gene polymorphisms in neonates exposed to antenatal corticosteroids (ACS) with respiratory outcomes, small for gestational age (SGA) and response to repeat ACS

Dificultades para codificar, relacionar y categorizar problemas verbales algebraicos: dos estudios con estudiantes de secundaria y profesores en formación

En resolución de problemas verbales por transferencia, la activación de problemas ya conocidos que sirvan de guía, depende de las analogías percibidas entre éstos y el problema a resolver. Se desarrollan dos estudios relacionados para analizar en qué características se basan los estudiantes para codificar problemas y detectar sus analogías, en tareas de categorización (sorting). Se utilizaron técnicas cuantitativas y cualitativas combinadas. Primero se analizó cómo los estudiantes de secundaria son influidos por diferentes variables características de problemas de ciencias. Una gran proporción de sujetos no fue capaz de percibir las analogías y diferencias adecuadas entre problemas. El segundo estudio trató de avanzar una explicación de estos resultados. El nivel académico y la familiaridad con las temáticas fueron factores significativos, pero los futuros profesores participantes mostraron demasiadas dificultades, alertando sobre la conveniencia de revisar algunos supuestos instruccionales habituales

Coulomb excitation of a 242Am isomeric target: E2 and e3 strengths, rotational alignment, and collective enhancement

A 98% pure242mAm (K = 5-, t1/2 = 141 years) isomeric target was Coulomb excited with a 170.5-MeV 40Ar beam. The selectivity of Coulomb excitation, coupled with the sensitivity of Gammasphere plus CHICO, was sufficient to identify 46 new states up to spin 18h{stroke} in at least four rotational bands; 11 of these new states lie in the isomer band, 13 in a previously unknown yrast Kπ = 6- rotational band, and 13 in a band tentatively identified as the predicted yrast Kπ = 5+ band. The rotational bands based on the Kπ = 5- isomer and the 6-bandhead were populated by Coulomb excitation with unexpectedly equal cross sections. The γ -ray yields are reproduced by Coulomb excitation calculations using a two-particle plus rotor model (PRM), implying nearly complete ΔK = 1 mixing of the two almost-degenerate rotational bands, but recovering the Alaga rule for the unperturbed states. The degeneracy of the 5- and 6- bands allows for precise determination of the mixing interaction strength V, which approaches the strong-mixing limit; this agrees with the 50% attenuation of the Coriolis matrix element assumed in the model calculations. The fractional admixture of the I πK= 6-6 state in the nominal 6-5 isomer band state is measured within the PRM as 45.6+0.3-1.1%. The E2 and M1 strengths coupling the 5- and 6- bands are enhanced significantly by the mixing, while E1 and E2 couplings to other low-K bands are not measurably enhanced. The yields of the 5+ band are reproduced by an E3 strength of ≈15 W.u., competitive with the interband E2 strength. Alignments of the identified two-particle Nilsson states in 242Am are compared with the single-particle alignments in 241Am

How well do we understand the reaction rate of C burning?

Carbon burning plays a crucial role in stellar evolution, where this reaction is an important route for the production of heavier elements. A particle-γ coincidence technique that minimizes the backgrounds to which this reaction is subject and provides reliable cross sections has been used at the Argonne National Laboratory to measure fusion cross-sections at deep sub-barrier energies in the 12C+12C system. The corresponding excitation function has been extracted down to a cross section of about 6 nb. This indicates the existence of a broad S-factor maximum for this system. Experimental results are presented and discussed

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed