Characterization of an Orphan Diterpenoid Biosynthetic Operon from Salinispora arenicola

While more commonly associated with plants than microbes, diterpenoid natural products have been reported to have profound effects in marine microbe–microbe interactions. Intriguingly, the genome of the marine bacterium Salinispora arenicola CNS-205 contains a putative diterpenoid biosynthetic operon, terp1. Here recombinant expression studies are reported, indicating that this three-gene operon leads to the production of isopimara-8,15-dien-19-ol (4). Although 4 is not observed in pure cultures of S. arenicola, it is plausible that the terp1 operon is only expressed under certain physiologically relevant conditions such as in the presence of other marine organisms

Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative

Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multi-disciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments

SCF VERTICAL EXCITATION ENERGIES AND ADIABATIC STATE CORRELATION DIAGRAM FOR LINEAR NO2+NO^{+}_{2}

$^{1}$D. G. Hopper, M. Krauss, and A. C. Wahl, ``MCSCF/CI Vertical and Adiabatic Excitation Energies for $N_{2}O$,'' to be submitted. This work was supported by USAF Office of Scientific Research.""Author Institution: Science Applications, Incorporated; National Bureau of Standards; Brehm LaboratoryThe SCF vertical excitation energies have been computed for linear $NO_{2}^{+}$ with 4s 2p and 4s 2pld base augmented for some states with diffuse functions. All states obtainable by one electron excitation from the $4\sigma_{g}, 3\sigma_{u}, 1\Pi_{u}$ and $1\Pi_{g}$ orbitals into the $5\sigma_{g}, 4\sigma_{u}$, and $2\Pi_{u}$ orbitals have been considered at this point. Each state was separately optimized at the computed geometries for $NO_{2}{^{+}}(X^{1}\Sigma_{g}{^{+}})$ resulting from use of the $4s2p(R_{NO} = 2.12$ a.u.) or 4s2pld ($R_{NO} = 2.07$ a.u.) basis. Results were also obtained at $R_{NO} = 2.25$ a.u., the equilibrium bond length of $NO_{2} (X^{2}A_{1})$. All excited states are more stable at 2.25 than at 2.12 a.u. by 0.5-2.0 eV. Furthermore, the 4s2pld excitation energies are 1-2 eV greater than the 4s2p. It is expected that roughly half of the polarization effect is due to decrease in the bond length calculated for $NO_{2}{^{+}}(X^{1}\Sigma_{g}{^{+}})$ when polarisation functions are included. The remaining half is due to the differential effect of the polarization functions on the ground and excited states - an effect similar to that previously found in calculations on the isoelectronic neutral $N_{2}O$.$^{1}$ Two large gaps of $\sim 5eV$ occur in the spectrum. The first gap separates the ground state from the $1\pi{_{g}}^{3}2\pi_{u}$ multiplet of states. The second gap separates that multiplet from a group of higher states resulting from the excitations $1\pi_{u}{^{4}}\rightarrow 1\pi_{u}{^{3}}2\pi_{u}, 1\pi_{g} {^{4}}\rightarrow 1\pi_{g} {^{3}}5\sigma_{g}, 1\pi_{g}{^{4}}\rightarrow 1\pi_{g}{^{3}}4\sigma_{u}, 4\sigma_{g}{^{2}}\rightarrow 4\sigma_{g} 2\pi_{u}$. The addition of s functions with exponent 0.025 showed the $5\sigma_{g}$ orbital to have considerable diffuse character and to be concentrated mainly on the nitrogen atom. Thus, the higher grouping of states involves diffuse and valence states interleaved. Correlated calculations on selected members of each group of excited states are in progress. The present work is part of a project on potential surfaces and spectra for air triatomics now ongoing at Science Applications, Incorporated

Spark Source Mass Spectrographic Analysis of Gallium Arsenide for Trace Oxygen and Carbon Using Liquid Helium Cryopumping

A spark source mass spectrometric system has been developed for trace levels of oxygen and carbon in gallium arsenide using liquid helium cryopumping of the source chamber. Following bake-out, a collector positioned inside the source chamber is cooled using a controlled flow of liquid helium. Residual back-ground gases are more effectively removed than with liquid nitrogen and detectabilities of 0.02 ppma for oxygen and 0.05 ppma for carbon have been obtained. Routine analyses are carried out with a moderate consumption of liquid helium

Spark Source Mass Spectrographic Analysis of Gallium Arsenide for Trace Oxygen and Carbon Using Liquid Helium Cryopumping

A spark source mass spectrometric system has been developed for trace levels of oxygen and carbon in gallium arsenide using liquid helium cryopumping of the source chamber. Following bake-out, a collector positioned inside the source chamber is cooled using a controlled flow of liquid helium. Residual back-ground gases are more effectively removed than with liquid nitrogen and detectabilities of 0.02 ppma for oxygen and 0.05 ppma for carbon have been obtained. Routine analyses are carried out with a moderate consumption of liquid helium