One approach to organic synthesis is retrosynthetic analysis. With this approach a chemist will start with the structure of their target molecule and progressively cut bonds to create simpler ...molecules. Reversing this process gives a synthetic route to the target molecule from simpler starting materials. This “disconnection” approach to synthesis is now a fundamental part of every organic synthesis course.Organic Synthesis: The Disconnection Approach, 2ndEditionintroduces this important technique, to help students to design their own organic syntheses. There are forty chapters: those on the synthesis of given types of molecules alternate with strategy chapters in which the methods just learnt are placed in a wider context. The synthesis chapters cover many ways of making each type of molecule starting with simple aromatic and aliphatic compounds with one functional group and progressing to molecules with many functional groups. The strategy chapters cover questions of selectivity, protection, stereochemistry, and develop more advanced thinking via reagents specifically designed for difficult problems.Examples are drawn from pharmaceuticals, agrochemicals, natural products, pheromones, perfumery and flavouring compounds, dyestuffs, monomers, and intermediates used in more advanced synthetic work. Reasons for wishing to synthesise each compound are given.This second edition has been fully revised and updated with a modern look. Recent examples and techniques are included and illustrated additional material has been added to take the student to the level required by the sequel, “Organic Synthesis: Strategy and Control”.Several chapters contain extensive new material based on courses that the authors give to chemists in the pharmaceutical industry.Organic Synthesis: The Disconnection Approach, 2ndeditionprovides a full course in retrosynthetic analysis for chemistry and biochemistry students and a refresher for organic chemists working in industry and academia.
The development and refinement of array comparative genomic hybridization has led to expanded applications as a diagnostic tool. Recent reports suggest a high diagnostic yield for array comparative ...genomic hybridization in autism spectrum disorders. The objective of this study was to determine the diagnostic yield in array comparative genomic hybridization for autism at the University of Nebraska Medical Center. The authors report the diagnostic yield of array comparative genomic hybridization in 89 samples with a primary indication of autism. Clinical information was reviewed for 89 identified cases. Twenty-one cases were excluded because of ambiguous information regarding the diagnosis, a diagnosis other than autism, or abnormal karyotype. Of 68 cases referred for array comparative genomic hybridization testing with a primary indication of autism, 14 (21%) had abnormal findings. This study supports array comparative genomic hybridization in the etiologic evaluation of autism and elevation of array to a first tier diagnostic test.
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The angular pattern of sunlight reflected by snow is altered by surface roughness, which in the interior of Antarctica is usually in the form of meter‐scale longitudinal erosional features ...(sastrugi), whose axes align with the direction of strong winds. The bidirectional reflectance distribution function (BRDF) changes over the course of a day as the solar azimuth changes relative to the sastrugi axis. The normalized BRDF, or “anisotropic reflectance factor” R, was measured at South Pole Station from a 22‐m tower at 600, 660, and 900 nm wavelengths. The R pattern was similar at the three wavelengths; it probably varies little from 300 to 900 nm. Measurements were made at solar zenith angles θ0 from 67° to 90°, over the full range of viewing zenith angle (θr), azimuth angle between Sun and view (ϕ), and azimuth angle between Sun and sastrugi (ϕsas). Variation of R with ϕsas was notable; sastrugi oriented perpendicular to the solar beam cause a reduction of the forward peak, and sastrugi at an oblique angle cause R to lose its symmetry about the solar azimuth. However, the effects of sastrugi are mostly restricted to large viewing zenith angles, so remote sensing of albedo and atmospheric properties can be carried out accurately without knowledge of sastrugi height and orientation if only near‐nadir views are used. This recommendation is opposite that for observations of broken clouds over dark surfaces, for which large θr is preferred. A parameterization of R is developed, valid for viewing angles θr ≤ 50°. Sastrugi can cause a reduction of the snow albedo by altering the angle of incidence and by trapping of photons. For the small sastrugi of the Antarctic Plateau, the albedo is unaffected at visible wavelengths but can be reduced by a few percent at near‐infrared wavelengths when the Sun is low.
Visual cloud reports from land and ocean regions of the Arctic are analyzed for total cloud cover. Trends and interannual variations in surface cloud data are compared to those obtained from Advanced ...Very High Resolution Radiometer (AVHRR) and Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) satellite data. Over the Arctic as a whole, trends and interannual variations show little agreement with those from satellite data. The interannual variations from AVHRR are larger in the dark seasons than in the sunlit seasons (6% in winter, 2% in summer); however, in the surface observations, the interannual variations for all seasons are only 1%–2%. A large negative trend for winter found in the AVHRR data is not seen in the surface data. At smaller geographic scales, time series of surface- and satellite-observed cloud cover show some agreement except over sea ice during winter. During the winter months, time series of satellite-observed clouds in numerous grid boxes show variations that are strangely coherent throughout the entire Arctic.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Endometriosis is a common gynecologic problem of unknown etiology. Estrogen dependence and immune modulation are established features of this disease and recently environmental contaminants have been ...suggested to play a role in the pathobiology of endometriosis as well. Previous work in nonhuman primates has shown that exposure to the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is associated with an increased prevalence and severity of endometriosis. Further animal experiments have implicated dioxin and dioxin-like compounds in this disease. Rodent studies support the plausibility for a role of environmental contaminants in the pathophysiology of endometriosis although a convincing mechanistic hypothesis has yet to be advanced. Small hospital-based case-control studies have failed to provide compelling evidence for or against an association of environmental contaminants and endometriosis. Herein we review the available literature that provides evidence that dioxin and dioxin-like compounds are potent modulators of immune and endocrine function critical to the pathobiology of endometriosis. Furthermore, perspectives on the potential mechanism(s) of dioxin and dioxin-like compound-induced toxicity in endometriosis, important knowledge needs, potential animal models for endometriosis studies, and considerations integral to future human case-control studies are discussed.
Nylon toughened epoxy/SWCNT composites Sun, Luyi; Warren, G. L.; Davis, D. ...
Journal of materials science,
2011/1, Volume:
46, Issue:
1
Journal Article
Peer reviewed
Epoxy/single-walled carbon nanotube (SWCNT) composites toughened by nylon particles (epoxy/SWCNT/nylon) were prepared. The SWCNTs were functionalized by oxidation and subsequent grafting with ...sulfanilamide. It was found that surface functionalization can effectively improve the dispersion of SWCNTs in epoxy, thus improving composite mechanical properties. Meanwhile, preformed nylon particles were utilized to enhance the fracture toughness of the composites. The epoxy/SWCNT/nylon composites prepared exhibit simultaneously improved stiffness, strength, and toughness. B-staged (partially cured) epoxy/SWCNT/nylon composites were successfully cast into thin films by manipulating degree of cure and viscosity. These thin films can be seamlessly integrated into laminated composite systems upon heating for improving mechanical properties and compression after impact strength of the laminated composites.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Alum Al₂(SO₄)₃·14H₂O is a common poultry litter amendment used to decrease water-soluble phosphorus or reduce ammonia volatilization, or both. Although the physiochemical effects of alum addition ...have been well researched, little attention has been given to the poultry litter microbial communities. The goal of this study was to use molecular biological methods denaturing gradient gel electrophoresis (DGGE), community cloning, and quantitative real-time PCR to characterize general, group-specific and pathogenic microbial communities in alum (10% wt/wt) and non-alum-treated litter. According to quantitative real-time PCR analyses, alum addition to the poultry litter resulted in significant reductions in both Campylobacter jejuni and Escherichia coli concentrations by the end of the first month of the experiment (3 log and 2 log, respectively). The concentrations of Salmonella spp. were below detection (<5 x 10³ cell·g⁻¹ of litter) for the entire experiment. The DGGE analyses revealed significant reductions in the Clostridium/Eubacterium and low %GC gram-positive groups in the alum-treated litters by the end of the first month, with no bands detectable for either group after 8 wk of incubation. Conversely, minimal effects of alum addition were observed in the Actinomycetes community. The most significant shift in the microbial community (based on DGGE analyses) occurred in the fungal population, with a large increase in diversity and abundance within 1 mo of alum addition (1 dominant band on d 0 to 9 dominant bands at 4 wk). Specifically, the incidence of Aspergillus spp. increased from 0 to 50% of the sequences in fungal clone libraries (n = 80) over the course of the experiment. This suggests that the addition of alum to poultry litter potentially shifts the microbial populations from bacterially dominated to dominated by fungi. The ramifications of this shift in dominance are still unknown, and future work will be aimed at characterizing these fungi and elucidating their role in the acidified litter environment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Decisions about where to fixate are highly variable and often inefficient. In the current study, we investigated whether such decisions would improve with increased motivation. Participants had to ...detect a discrimination target, which would appear in one of two boxes, but only after they chose a location to fixate. The distance between boxes determines which location to fixate to maximise the probability of being able to see the target: participants should fixate between the two boxes when they are close together, and on one of the two boxes when they are far apart. We “gamified” this task, giving participants easy-to-track rewards that were contingent on discrimination accuracy. Their decisions and performance were compared to previous results that were gathered in the absence of this additional motivation. We used a Bayesian beta regression model to estimate the size of the effect and associated variance. The results demonstrate that discrimination accuracy does indeed improve in the presence of performance-related rewards. However, there was no difference in eye movement strategy between the two groups, suggesting this improvement in accuracy was not due to the participants making more optimal eye movement decisions. Instead, the motivation encouraged participants to expend more effort on other aspects of the task, such as paying more attention to the boxes and making fewer response errors.
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