4,867 research outputs found
Founders\u27 Day 1960
Founders\u27 Day 1960 with speakers President Harvey Rice, Professor O.T. Walter, as well as Edmund Wood, Kay Lorans, Fred Koch, and George Bonniwell.
Reel #3
Taming Ambident Triazole Anions: Regioselective Ion-Pairing Catalyzes Direct N-Alkylation with Atypical Regioselectivity
Controlling the regioselectivity
of ambident nucleophiles toward
alkylating agents is a fundamental problem in heterocyclic chemistry.
Unsubstituted triazoles are particularly challenging, often requiring
inefficient stepwise protectionâdeprotection strategies and
prefunctionalization protocols. Herein we report on the alkylation
of archetypal ambident 1,2,4-triazole, 1,2,3-triazole, and their anions,
analyzed by in situ <sup>1</sup>H/<sup>19</sup>F NMR, kinetic modeling,
diffusion-ordered NMR spectroscopy, X-ray crystallography, highly
correlated coupled-cluster computations [CCSDÂ(T)-F12, DF-LCCSDÂ(T)-F12,
DLPNO-CCSDÂ(T)], and Marcus theory. The resulting mechanistic insights
allow design of an organocatalytic methodology for ambident control
in the <i>direct</i> N-alkylation of unsubstituted triazole
anions. Amidinium and guanidinium receptors are shown to act as strongly
coordinating phase-transfer organocatalysts, shuttling triazolate
anions into solution. The intimate ion pairs formed in solution retain
the reactivity of liberated triazole anions but, by virtue of highly
regioselective ion pairing, exhibit alkylation selectivities that
are completely inverted (1,2,4-triazole) or substantially enhanced
(1,2,3-triazole) compared to the parent anions. The methodology allows
direct access to 4-alkyl-1,2,4-triazoles (<i>rr</i> up to
94:6) and 1-alkyl-1,2,3-triazoles (<i>rr</i> up to 99:1)
in one step. Regioselective ion pairing acts in effect as a noncovalent
in situ protection mechanism, a concept that may have broader application
in the control of ambident systems
A novel antibody-based biosensor method for the rapid measurement of PAH contamination in oysters
Conventional PAH analytical methods are time-consuming and expensive, limiting their utility in time sensitive events (i.e. oil spills and floods) or for widespread environmental monitoring. Unreliable and inefficient screening methods intended to prioritize samples for more extensive analyses exacerbate the issue. Antibody-based biosensor technology was implemented as a quantitative screening method to measure total PAH concentration in adult oysters (Crassostrea virginica) â a well-known bioindicator species with ecological and commercial significance. Individual oysters were analyzed throughout the historically polluted Elizabeth River watershed (Virginia, USA). Significant positive association was observed between biosensor and GCâMS measurements that persisted when the method was calibrated for different regulatory subsets of PAHs. Mapping of PAH concentrations in oysters throughout the watershed demonstrates the utility of this technology for environmental monitoring. Through a novel extension of equilibrium partitioning, biosensor technology shows promise as a cost-effective analysis to rapidly predict whole animal exposure to better assess human health risk as well as improve monitoring efforts
Preliminary study of the influence of red blood cells morphometry on the species determinism of domestic animals
Aim: This survey was realized on cattle, sheep, goats, horses, and dogs, in order to study the influence of three morphometric parameters: the diameter, the circumference and the surface of red blood cells on the determinism of these species.
Materials and Methods: For each species, blood samples were taken from 15 adult female by jugular venipuncture with confection of blood smears on microscope slides immediately after blood collection and stained according to the method of May-GrĂŒndwald Giemsa. Morphometric study was realized using the software OPTIKA Pro Vision. To better describe the results, the statistical analysis was assessed by using the descriptive Boxplots test, ANOVA, and the Student's t-test.
Results: The morphometric parameters of red blood cells are biggest in dogs followed by horses, cattle, and sheep, while goats have the lowest ones.
Conclusion: This investigation allowed us to show that from a drop of blood we can have an idea about the animal species taking into account the diameter, the circumference, and the surface of erythrocytes
Optical Design for the Submillimeter and Far InfraRed Experiment (SAFIRE)
The SAFIRE, the Submillimeter and Far InfraRed Experiment, was designed for interstellar physics in the airborne Observatory SOFIA. SAFIRE is a cryogenic Echelle Grating spectrograph for covering 27 to 470 microns; with R ranging from 2-6,000. Here we will discuss the details of the optical design, the design process, and the performance of the instrumen
Government helper and citizen advocate? A case study of the multiple roles and pressures facing a nongovernmental organization contracted by government to strengthen community health in northern India
While nongovernmental organizations (NGOs) can potentially
strengthen valuable citizen political engagement, NGOs that are
increasingly oriented towards donor and government contracts may
instead contribute to depoliticizing development. Amidst competing
pressures, NGO experiences and agency in managing multiple roles
require examination. We present a qualitative case study of an NGO
implementing a governmentâdesigned intervention to strengthen
Village Health, Sanitation, and Nutrition Committees (VHSNCs) in
rural north India. Despite a challenging context of community
scepticism and poor government services, the NGO did successfully
form VHSNCs by harnessing its respected interlocutor status,
preexisting relationships, and ability to âsellâ the VHSNC as a
mechanism for improving local wellâbeing. While the VHSNC enabled
community members to voice concerns to government officials,
improvements often failed to meet community expectations. NGO
staff endured community frustration on one hand and rebuffs from
lowerâlevel officials on the other, while feeling undersupported by
the government contract. Consequently, although contracted to
strengthen a community institution, the NGO increasingly worked
alongside VHSNC members to try to strengthen the public sector.
Contrary to assumptions that NGOs become âtamedâ through taking government contracts, being contracted to deliver inputs for
community participation was intertwined with microlevel political
action, though this came at a cost to the NGO
Organic fuel cell methods and apparatus
A liquid organic, fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion.TM.. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon.TM.-binder structure is immersed within a Nafion.TM./methanol bath to impregnate the electrode with Nafion.TM.. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells
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