5-Methoxyl Participation in Solvolysis and Secondary Deuterium Isotope Effects

Specifically deuterated 4-methoxy-1-pentyl broij\u27ylates (IP- 1,1-d2, IP-2,2-d2) and 5-methoxy-2-pentyl brosylates (IS-2-d, 1S- -1 ,1,1 - d3, 1S-OCD3) were prepared, their solvolysis rates measured in 950/o ethanol and the corresponding kinetic secondary deuterium isotope effects calculated. It was found that the a-effects are strongly reduced in magnitude, which is in contrast with results obtained with several compounds solvolyzing via n- or CJ-participation. The effect found with IP-l,1-d2 (kHfkD = 0.96) is significantly different from the one measured with IS-2-d (kHfkD = 1.06). This difference in the magnitude of the effects must reflect a relatively small difference in the structures of the two transition states, since both IP and IS solvolyze via the same intermediate 2. It is concluded that the magnitude of the u- effP.ct is a sensitive measure of the amount of bridging only if the new bond is already quite strong in the transition state. B-Deuterated brosylates give small effects which differ in magnitude (kH/kD = 0.96 with IP-2,2-d2 and 1.08 with IS-1,1,1-da) corroborating the conclusion that the new C-0 bond is strong in the transition state of both reactions but stronger with IP than with IS. Results obtained in this work are in accord with the earlier conclusion that reduced B-effects in solvolysis of exo-2-norbornyl, 3-cholesteryl, cyclobutyl and 1-methylcyclobutyl derivatives are due to bridging. The inverse isotope effect obtained with IS-OCD3 (kH/kD=0.95) is »inductive« in origin and indicates that the methoxy oxygen bears a considerable amount of positive charge in the reaction transition state

Non-Contact Measurement of Thermal Diffusivity in Ion-Implanted Nuclear Materials

Knowledge of mechanical and physical property evolution due to irradiation damage is essential for the development of future fission and fusion reactors. Ion-irradiation provides an excellent proxy for studying irradiation damage, allowing high damage doses without sample activation. Limited ion-penetration-depth means that only few-micron-thick damaged layers are produced. Substantial effort has been devoted to probing the mechanical properties of these thin implanted layers. Yet, whilst key to reactor design, their thermal transport properties remain largely unexplored due to a lack of suitable measurement techniques. Here we demonstrate non-contact thermal diffusivity measurements in ion-implanted tungsten for nuclear fusion armour. Alloying with transmutation elements and the interaction of retained gas with implantation-induced defects both lead to dramatic reductions in thermal diffusivity. These changes are well captured by our modelling approaches. Our observations have important implications for the design of future fusion power plants.Comment: 15 pages, 3 figure

LANDSAT TM image data quality analysis for energy-related applications

This project represents a no-cost agreement between National Aeronautic Space Administration Goddard Space Flight Center (NASA GSFC) and the Pacific Northwest Laboratory (PNL). PNL is a Department of Energy (DOE) national laboratory operted by Battelle Memorial Institute at its Pacific Northwest Laboratories in Richland, Washington. The objective of this investigation is to evaluate LANDSAT's thematic mapper (TM) data quality and utility characteristics from an energy research and technological perspective. Of main interest is the extent to which repetitive TM data might support DOE efforts relating to siting, developing, and monitoring energy-related facilities, and to basic geoscientific research. The investigation utilizes existing staff and facility capabilities, and ongoing programmatic activities at PNL and other DOE national laboratories to cooperatively assess the potential usefulness of the improved experimental TM data. The investigation involves: (1) both LANDSAT 4 and 5 TM data, (2) qualitative and quantitative use consideration, and 3) NASA P (corrected) and A (uncorrected) CCT analysis for a variety of sites of DOE interest. Initial results were presented at the LANDSAT Investigator's Workshops and at specialized LANDSAT TM sessions at various conferences

CD-ROM publication of the Mars digital cartographic data base

The recently completed Mars mosaicked digital image model (MDIM) and the soon-to-be-completed Mars digital terrain model (DTM) are being transcribed to optical disks to simplify distribution to planetary investigators. These models, completed in FY 1991, provide a cartographic base to which all existing Mars data can be registered. The digital image map of Mars is a cartographic extension of a set of compact disk read-only memory (CD-ROM) volumes containing individual Viking Orbiter images now being released. The data in these volumes are pristine in the sense that they were processed only to the extent required to view them as images. They contain the artifacts and the radiometric, geometric, and photometric characteristics of the raw data transmitted by the spacecraft. This new set of volumes, on the other hand, contains cartographic compilations made by processing the raw images to reduce radiometric and geometric distortions and to form geodetically controlled MDIM's. It also contains digitized versions of an airbrushed map of Mars as well as a listing of all feature names approved by the International Astronomical Union. In addition, special geodetic and photogrammetric processing has been performed to derive rasters of topographic data, or DTM's. The latter have a format similar to that of MDIM, except that elevation values are used in the array instead of image brightness values. The set consists of seven volumes: (1) Vastitas Borealis Region of Mars; (2) Xanthe Terra of Mars; (3) Amazonis Planitia Region of Mars; (4) Elysium Planitia Region of Mars; (5) Arabia Terra of Mars; (6) Planum Australe Region of Mars; and (7) a digital topographic map of Mars

Earth sciences waste disposal investigations, January--June 1966

An evaluation is given of the ground water contamination resulting from disposal of plant effluents at Hanford. Analytical results are presented for gross beta activity in the unconfined ground water aquifer and gross beta activity at depths in the ground water. Results are given where concentrations of radionuclides are above the routine detection limit for gross beta. The average concentrations detected during the previous report period are listed for comparison. (JSR

The Upper Limit on Rates of Proton Transfer

The Bronsted plot for hydrolysis of diphenyldiazomethane by carboxylic acids is smooth but curved, approaching an asymptotic limit below 10 mo1-1 dm3 s-1• Regardless of the details of the theory used, such a limit requires that the transition state is approached via a state (or virtual state) substantially (- 70 kJ mol-1) above the starting state in free energy, but still having an intact bond from H+ to its original conjugate base. Such a state has been called a reaction complex,6 and is thought to be analogous to the intimate ion pair of solvolysis reactions

Postoperative fluid collection after hybrid debranching and endovascular repair of thoracoabdominal aortic aneurysms

ObjectiveHybrid thoracic endovascular aneurysm repair (H-TEVAR) to include visceral and renal debranching has emerged as a potential therapeutic option for thoracoabdominal aneurysms (TAAA). This study was performed to characterize the frequently noted development of postoperative fluid collections surrounding the bypass grafts.MethodsAll patients undergoing H-TEVAR from 2000-2010 (n = 39, 43.6% male) were identified. One hundred thirty-two bypasses were constructed (median 4 per patient) using either polyester (30), thin-walled polytetrafluoroethylene (ePTFE, 100) or saphenous vein (2). Follow-up computed tomography (CT) imaging was routinely performed at 1 and 6 months, and annually thereafter.ResultsOf the 37 patients with one follow-up CT, 20 (54.1%) were found to have fluid collections. The natural history of the 17 patients with collections and further follow-up imaging was variable, with 2 resolving, 6 stable, and 9 enlarging. Two patients with collections developed evidence of graft infection requiring reoperation. Two patients with enlarging sterile collections required evacuation for symptoms. By multivariate analysis, both preoperative creatinine (P = .005) and number of bypasses constructed (P = .04) independently correlated with the development of a fluid collection.ConclusionsPostoperative fluid collections following hybrid debranching procedures identified in this series represent a unique complication not previously described. The subsequent clinical course of these fluid collections is variable and ranges from benign to frank graft infection and relate both to patient factors, as well as specific operative strategies. Longer-term studies with more robust numbers of patient numbers are warranted to determine whether this complication may limit the long-term durability of this procedure

Postoperative fluid collection after hybrid debranching and endovascular repair of thoracoabdominal aortic aneurysms

ObjectiveHybrid thoracic endovascular aneurysm repair (H-TEVAR) to include visceral and renal debranching has emerged as a potential therapeutic option for thoracoabdominal aneurysms (TAAA). This study was performed to characterize the frequently noted development of postoperative fluid collections surrounding the bypass grafts.MethodsAll patients undergoing H-TEVAR from 2000-2010 (n = 39, 43.6% male) were identified. One hundred thirty-two bypasses were constructed (median 4 per patient) using either polyester (30), thin-walled polytetrafluoroethylene (ePTFE, 100) or saphenous vein (2). Follow-up computed tomography (CT) imaging was routinely performed at 1 and 6 months, and annually thereafter.ResultsOf the 37 patients with one follow-up CT, 20 (54.1%) were found to have fluid collections. The natural history of the 17 patients with collections and further follow-up imaging was variable, with 2 resolving, 6 stable, and 9 enlarging. Two patients with collections developed evidence of graft infection requiring reoperation. Two patients with enlarging sterile collections required evacuation for symptoms. By multivariate analysis, both preoperative creatinine (P = .005) and number of bypasses constructed (P = .04) independently correlated with the development of a fluid collection.ConclusionsPostoperative fluid collections following hybrid debranching procedures identified in this series represent a unique complication not previously described. The subsequent clinical course of these fluid collections is variable and ranges from benign to frank graft infection and relate both to patient factors, as well as specific operative strategies. Longer-term studies with more robust numbers of patient numbers are warranted to determine whether this complication may limit the long-term durability of this procedure

Population-Based Prevalence of CDKN2A Mutations in Utah Melanoma Families

Cyclin-dependent kinase inhibitor 2A (CDKN2A or p16) is the major melanoma predisposition gene. In order to evaluate the candidacy for genetic testing of CDKN2A mutations among melanoma prone families, it is important to identify characteristics that predict a high likelihood of carrying a CDKN2A mutation. We primarily used a unique Utah genealogical resource to identify independent melanoma prone families whom we tested for mutations in CDKN2A, cyclin-dependent kinase 4, and alternate reading frame. We sampled 60 families which met the inclusion criteria of two or more affected first-degree relatives. We found four different pathogenic CDKN2A mutations in five families, mutations of uncertain significance in two families, and known polymorphisms in three families. One of the mutations of uncertain significance, 5′ untranslated region −25C>T, has not been previously described. Among our population-based set of Utah families, the prevalence of CDKN2A mutations was 8.2% (4/49); the overall prevalence when physician-referred pedigrees were also considered was between 8.3% (5/60) and 10% (6/60). Having four or more first- or second-degree relatives with melanoma, or a family member with ≥3 primary melanomas, correlated strongly with carrying a CDKN2A mutation. We observed a significantly elevated rate of pancreatic cancer in one of four families with a deleterious CDKN2A mutation