1,572 research outputs found

    Chemoselective Suzuki-Miyaura cross-coupling via kinetic transmetallation

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    Chemoselective Suzuki-Miyaura cross-coupling generally requires a designed deactivation of one nucleophile towards transmetallation. Here we show that boronic acids can be chemoselectively reacted in the presence of ostensibly equivalently reactive boronic acid pinacol (BPin) esters by kinetic discrimination during transmetallation. Simultaneous electrophile control allows sequential chemoselective cross-couplings in a single operation in the absence of protecting groups

    Lessons Learned from the Performance of a Degradable Shale Embankment: Case Study

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    Degradable shales are sedimentary rocks with properties that can vary from those of solid rock to soil like materials if subjected to wetting and drying cycles. If the potential for degradation of the shale is not identified on time, rock like particles could be used as strong embankment material. After wetting and drying cycles, degradation occurs and the initial large voids formed between the generally uniform rock particles are filled with smaller fragments, resulting in significant settlements and slope instability. This paper present a case study of a 40 foot (12.2m) approach embankment having 1.5H:1V slopes that was unintentionally constructed with degradable shale. Preliminary testing showed that even though some samples were clearly degradable shale other samples exhibited durability indexes greater than the values generally accepted as durable rock. After embankment completion a settlement monitoring program was instituted for the prescribed quarantine period prior to construction of the bridge abutments. The embankment settled more than initially predicted and finally stabilized after more than 1 feet (0.305m) of internal deformation. A laboratory testing program was developed to investigate the causes of the observed degradation

    Space biology initiative program definition review. Trade study 6: Space Station Freedom/spacelab modules compatibility

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    The differences in rack requirements for Spacelab, the Shuttle Orbiter, and the United States (U.S.) laboratory module, European Space Agency (ESA) Columbus module, and the Japanese Experiment Module (JEM) of Space Station Freedom are identified. The feasibility of designing standardized mechanical, structural, electrical, data, video, thermal, and fluid interfaces to allow space flight hardware designed for use in the U.S. laboratory module to be used in other locations is assessed

    Space biology initiative program definition review. Trade study 3: Hardware miniaturization versus cost

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    The optimum hardware miniaturization level with the lowest cost impact for space biology hardware was determined. Space biology hardware and/or components/subassemblies/assemblies which are the most likely candidates for application of miniaturization are to be defined and relative cost impacts of such miniaturization are to be analyzed. A mathematical or statistical analysis method with the capability to support development of parametric cost analysis impacts for levels of production design miniaturization are provided

    Space biology initiative program definition review. Trade study 4: Design modularity and commonality

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    The relative cost impacts (up or down) of developing Space Biology hardware using design modularity and commonality is studied. Recommendations for how the hardware development should be accomplished to meet optimum design modularity requirements for Life Science investigation hardware will be provided. In addition, the relative cost impacts of implementing commonality of hardware for all Space Biology hardware are defined. Cost analysis and supporting recommendations for levels of modularity and commonality are presented. A mathematical or statistical cost analysis method with the capability to support development of production design modularity and commonality impacts to parametric cost analysis is provided

    Epidemiology of glenohumeral dislocation and subsequent instability in an urban population

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    Background: Glenohumeral dislocation is the most commonly encountered adult joint instability. The epidemiology in the United Kingdom and worldwide is unclear and often limited to young, active groups that are not representative of general populations. Information regarding epidemiology and outcome from a first dislocation is useful for trauma service planning and patient counseling. We calculated the incidence of shoulder instability after a first dislocation in our urban population and investigated predictors of recurrent instability. Methods: A prospectively collected trauma database was retrospectively examined to identify patients with a first-time dislocation. Demographics, subsequent dislocation, and instability details were collected from electronic patient records. Results: In a 38-month study period, 329 first dislocations occurred in a population of 475,147 with mean follow-up 28.5 months (range, 10-50 months). The overall incidence for first-time dislocations in this population was 21.9 per 100,000 population, of which 7.9% sustained a redislocation and 6.1% had further symptomatic instability. There were 18.8% with associated greater tuberosity fractures, 8.8% sustained a nerve injury, and 2.7% were posterior dislocations. A bimodal distribution was observed for males (peak incidence per 100,000 of 42.1 and 50.9 in 15-24 and ≥85 age groups, respectively), and unimodal for females (peak 45.7 in the 65-74 age group). Conclusion: We demonstrate a previously unreported burden of dislocation in older age groups and suggest a rate of recurrence lower than previously reported in the United Kingdom. The group aged 15 to 19 years was at the highest risk of recurrent dislocation and instability. Gender was not a significant predictor of instability

    Blade Tip Pressure Measurements Using Pressure Sensitive Paint

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    This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35

    Computed tomography-based anatomic assessment overestimates local tumor recurrence in patients with mass-like consolidation after stereotactic body radiotherapy for early-stage non-small cell lung cancer.

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    PURPOSE: To investigate pulmonary radiologic changes after lung stereotactic body radiotherapy (SBRT), to distinguish between mass-like fibrosis and tumor recurrence. METHODS AND MATERIALS: Eighty consecutive patients treated with 3- to 5-fraction SBRT for early-stage peripheral non-small cell lung cancer with a minimum follow-up of 12 months were reviewed. The mean biologic equivalent dose received was 150 Gy (range, 78-180 Gy). Patients were followed with serial CT imaging every 3 months. The CT appearance of consolidation was defined as diffuse or mass-like. Progressive disease on CT was defined according to Response Evaluation Criteria in Solid Tumors 1.1. Positron emission tomography (PET) CT was used as an adjunct test. Tumor recurrence was defined as a standardized uptake value equal to or greater than the pretreatment value. Biopsy was used to further assess consolidation in select patients. RESULTS: Median follow-up was 24 months (range, 12.0-36.0 months). Abnormal mass-like consolidation was identified in 44 patients (55%), whereas diffuse consolidation was identified in 12 patients (15%), at a median time from end of treatment of 10.3 months and 11.5 months, respectively. Tumor recurrence was found in 35 of 44 patients with mass-like consolidation using CT alone. Combined with PET, 10 of the 44 patients had tumor recurrence. Tumor size (hazard ratio 1.12, P=.05) and time to consolidation (hazard ratio 0.622, P=.03) were predictors for tumor recurrence. Three consecutive increases in volume and increasing volume at 12 months after treatment in mass-like consolidation were highly specific for tumor recurrence (100% and 80%, respectively). Patients with diffuse consolidation were more likely to develop grade ≥ 2 pneumonitis (odds ratio 26.5, P=.02) than those with mass-like consolidation (odds ratio 0.42, P=.07). CONCLUSION: Incorporating the kinetics of mass-like consolidation and PET to the current criteria for evaluating posttreatment response will increase the likelihood of correctly identifying patients with progressive disease after lung SBRT

    Applying Pressure Sensitive Paint Technology to Rotor Blades

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    This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on rotorcrtaft blades in simulated forward flight at the 14- by 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The basics of the PSP method will be discussed and the modifications that were needed to extend this technology for use on rotor blades. Results from a series of tests will also be presented as well as several areas of improvement that have been identified and are currently being developed for future testing
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