2,135 research outputs found
Generation Of Electron Deficient Carbodiimides And Their Application In The Guanidine Forming, Zwitterionic 1,3-Diaza-Claisen Rearrangement
The 1,3-diaza Claisen rearrangement was initially discovered by the Madalengoitia group in the early 2000s. Tertiary, allylic, amines nucleophilically add to the carbon of a heterocumulene (isocyanate, isothiocyanate, or carbodiimide) to generate a zwitterion which then undergoes [3,3]-sigmatropic rearrangement. The rearrangements conducted with a carbodiimide generate guanidine-containing skeletons. The guanidine functional group is found in many biologically active products, making it a worthwhile chemical target.
To this end, strained, tertiary, allylic, amine 2-benzyl-2-azabicyclo[2.2.1]hept-5-ene reacts with in-situ generated carbodiimides in the 1,3-diaza-Claisen rearrangement to afford structurally interesting bicyclic guanidines. Use of more electron deficient carbodiimides makes these rearrangements more facile; however, there are not sufficient methods for the synthesis of highly electron deficient carbodiimides. The synthesis of such carbodiimides was explored through new synthetic methodologies for the dehydration of ureas and desulfurization of isothioureas and the carbodiimides were used in a series of intermolecular rearrangements with the strained, tertiary, allylic, amine.
The new methodologies for the synthesis of electron deficient carbodiimides were then applied to a series of intramolecular substrates, further expanding the 1,3-diaza Claisen rearrangement methodologies. To date series of bicyclic, tricyclic, and monocyclic guanidines of varying structures have been synthesized. The synthetic efforts towards these products are herein described
Probing the Goldstone equivalence theorem in Heavy Weak Doublet Decays
This paper investigates the decays from heavy higgsino-like weak-doublets
into Z, h bosons and missing particles. When pair-produced at the LHC, the
subsequent Z, h to 2l, 2b decays in the doublet decay cascade can yield 4l, 2l
2b, and 4b + MET + jets final states. Mutual observation of any two of these
channels would provide information on the the associated doublets' decay
branching fractions into a Z or h, thereby probing the Goldstone equivalence
relation, shedding additional light on the Higgs sector of beyond the Standard
Model theories, and facilitating the discrimination of various contending
models, in turn. We compare the Z/h decay ratio expected in the Minimal
Supersymmetric model, the Next-to Minimal Supersymmetric model and a minimal
singlet-doublet dark matter model. Additionally, we conduct a full Monte Carlo
analysis of the prospects for detecting the targeted final states during 14 TeV
running of the LHC in the context of a representative NMSSM benchmark model.Comment: As accepted to PRD; 15 pages, 12 figures, 5 table
Design, construction, and evaluation of a continuous band cutting mechanism for reducing shatter in soybeans
A large quantity of soybeans have been lost each year due to shatter caused by the cutterbar and other combine header components. A band blade cutting device was designed, constructed, and tested for effectiveness in reducing these shatter losses. The electrically driven band ran in a rectangular path around four 20.3 cm (8.0 in) diameter wheels. The blade thickness was limited to 0.05 cm (0.020 in) or less due to the stresses induced when traveling around the wheels. The blade return path precluded the use of a conventional reel. A reel having bats carried by chains was devised. The new header was attached to and powered by a Chain Machine Company SP-50 plot combine.
Laboratory tests were performed in which a plant carriage system was used to feed erect plants into the stationary headers of both the conventional and the experimental machine. An abrasive Grit-edge blade was used. The band-blade header was compared to the conventional cutterbar header on the bases of percent shatter loss, uncut (lodged and stubble) loss and total loss. Four levels of band blade speed between 460 and 910 m/min (1500 and 3000 ft/min) were used. Simulated ground speeds were set at four levels between 3.2 and 6.4 km/hr (2 and 4 mi/hr) while testing the band blade header. The conventional header was tested at 330 cycles/min and a simulated ground speed of 6.4 km/hr (4 mi/hr). Response surfaces of shatter, uncut, and total losses as a function of blade speed and ground speed of the band blade header were developed. Blade speeds of 910 m/min (3000 ft/min) reduced shatter below the levels found in the conventional header for all ground speeds. However, the uncut and total losses were not lower for the band blade header.
Five high speed cinema films were taken as part of the laboratory tests. The author concluded from the shatter tests and film studies that the abrasive blade did not cut rapidly enough. The abrasive surface did not positively engage the plant fibers. A high force normal to the cutting edge was required to aid the cutting action. The plants were excessively disturbed.
A toothed blade was selected for field tests after consideration of the laboratory results. A spring steel blade having a tooth pitch of 5.1 mm (5 teech per inch) was selected. Shatter, stalk, lodged, and stubble losses were collected from a 137- x 91-cm (54- x 36-in) area after the combine header had passed. Five blade speeds between 610 and 1830 m/min (2000 and 6000 ft/min) were used. Ground speeds were set at five levels between 1.6 and 4.8 km/hr (1.0 and 3.0 mi/hr). Moisture and maturity of the beans were monitored. The field tests were not sensitive enough to measure all effects adequately due to insufficient replication. The linear component of ground speed was found to significantly effect shatter at the 90 percent level of probability. Comparison of means between the band-blade header and the conventional header showed that shatter, lodged, and total losses were not different, but stalk and stubble losses were lower for the band blade header. The cutting action was smooth. Little plant disturbance was observed during operation in the field
Sensitivity to Z-prime and non-standard neutrino interactions from ultra-low threshold neutrino-nucleus coherent scattering
We discuss prospects for probing Z-prime and non-standard neutrino
interactions using neutrino-nucleus coherent scattering with ultra-low energy
(~ 10 eV) threshold Si and Ge detectors. The analysis is performed in the
context of a specific and contemporary reactor-based experimental proposal,
developed in cooperation with the Nuclear Science Center at Texas A&M
University, and referencing available technology based upon economical and
scalable detector arrays. For expected exposures, we show that sensitivity to
the Z-prime mass is on the order of several TeV, and is complementary to the
LHC search with low mass detectors in the near term. This technology is also
shown to provide sensitivity to the neutrino magnetic moment, at a level that
surpasses terrestrial limits, and is competitive with more stringent
astrophysical bounds. We demonstrate the benefits of combining silicon and
germanium detectors for distinguishing between classes of models of new
physics, and for suppressing correlated systematic uncertainties.Comment: As published in PRD; 13 pages, 7 figure
Non-standard interactions of solar neutrinos in dark matter experiments
Non-standard neutrino interactions (NSI) affect both their propagation
through matter and their detection, with bounds on NSI parameters coming from
various astrophysical and terrestrial neutrino experiments. In this paper, we
show that NSI can be probed in future direct dark matter detection experiments
through both elastic neutrino-electron scattering and coherent neutrino-nucleus
scattering, and that these channels provide complementary probes of NSI. We
show NSI can increase the event rate due to solar neutrinos, with a sharp
increase for lower nuclear recoil energy thresholds that are within reach for
upcoming detectors. We also identify an interference range of NSI parameters
for which the rate is reduced by approximately 40\%. Finally, we show that the
"dark side" solution for the solar neutrino mixing angle may be discovered at
forthcoming direct detection experiments.Comment: 12 pages, 5 figure
DETAILED GEOLOGIC MAPPING OF THE PARKSVILLE 7.5-MINUTE QUADRANGLE AND THE KINEMATICS OF EMPLACEMENT OF LARGE HORSES ALONG THE GREAT SMOKY FAULT, SOUTHEASTERN TENNESSEE
The Great Smoky fault is a major Alleghanian thrust fault in the southern Appalachians that separates the highly deformed and metamorphosed Blue Ridge to the east from the less deformed and unmetamorphosed Valley and Ridge to the west. The trace of the frontal Blue Ridge, as defined by the Great Smoky fault, displays a change in strike from ~010° to ~045° in or near the Parksville 7.5-minute quadrangle in southeastern Tennessee. This change in strike defines the southern arc of the Tennessee salient, which is a convex-to-the-foreland curve in the structural front of the southern Appalachians. Along the Great Smoky fault in the Parksville quadrangle are two large horses of Lower Cambrian Chilhowee Group rocks that could have affected the emplacement of the Great Smoky thrust sheet and caused the change in strike. Detailed geologic mapping of the Parksville quadrangle has shown that the northernmost horse is comprised of a section of Nebo Sandstone thrust over a section of Cochran Formation along a previously unmapped fault, with the intervening Nichols Shale removed. The southernmost horse is comprised of Cochran Formation and displays pervasive tectonic quartz veining. Analysis of hand samples and thin sections suggest that the horses were subjected to relatively low-temperature deformational conditions between approximately 300-400°C. Intense brittle and semi-ductile to ductile deformation occurs within the immediate vicinity of the Great Smoky fault zone but is not seen elsewhere in the horses, where primarily brittle deformation is observed. The lack of penetrative brittle and ductile deformation, the constraints on deformational temperatures, and the structural orientation of the Chilhowee Group horses suggests they were derived from the hanging wall of the Great Smoky thrust sheet. The emplacement of the horses likely did not affect the development of the southern limb of the Tennessee salient. Numerous horses occur along the Great Smoky fault, but no systematic change in geometry is observed where horses occur. Instead, the curvature of the Tennessee salient was likely controlled primarily by the irregular shape of the crystalline indenter, which, in the southern Appalachians, was the Blue Ridge-Piedmont megathrust sheet
A 125.5 GeV Higgs Boson in F-SU(5): Imminently Observable Proton Decay, A 130 GeV Gamma-ray Line, and SUSY Multijets & Light Stops at the LHC8
We establish that the light Higgs boson mass in the context of the No-Scale
Flipped SU(5) GUT with TeV scale vector-like matter multiplets (flippons) is
consistent with m_h = 125.5+-0.5 GeV in the region of the best supersymmetry
(SUSY) spectrum fit to low statistics data excesses observed by ATLAS in
multijet and light stop 5/fb SUSY searches at the LHC7. Simultaneous
satisfaction of these disparate goals is achieved by employing a minor decrease
in the SU(5) partial unification scale M_{32} to lower the flippon mass,
inducing a larger Higgs boson mass shift from the flippon loops. The reduction
in M_{32}, which is facilitated by a phenomenologically favorable reduction of
the low-energy strong coupling constant, moreover suggests an imminently
observable (e|mu)^+ pi^0 proton decay with a central value time scale of
1.7x10^34 years. At the same point in the model space, we find a lightest
neutralino mass of m_{\chi} = 145 GeV, which is suitable for the production of
130 GeV monochromatic gamma-rays through annihilations yielding associated
Z-bosons; a signal with this energy signature has been identified within
observations of the galactic center by the FERMI-LAT Space Telescope. In
conjunction with direct correlations to the fate of the ATLAS multijet and
light stop production channels presently being tested at the LHC8, we suggest
that the reality of a 125.5 GeV Higgs boson affords a particularly rich company
of specific and imminently testable associated observables.Comment: European Physical Journal C Version; 10 Pages, 2 Figures, 2 Table
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