49 research outputs found

    Influence of extraction methods on the composition of essential oils of Achillea millefolium L. from Lithuania

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    In this study, flowering aerial parts of Achillea millefolium were used as a matrix for supercritical CO2 extraction (SFE) of volatile oil. The collected extracts were analyzed by GC-FID and GC-MS methods and their composition were compared with that of the essential oil isolated by hydrodistillation (HD). The composition of the essential oil obtained by hydrodistillation and SFE methods is widely different. Indeed, the SFE volatile oil had a pale yellow color whereas the HD oil had a blue color due to the presence of chamazulene (48.0% vs. 4.3%). Other important constituents of HD oil were (E)- caryophyllene (19.5 %) and γ-muurolene (13.1%). The CO2 supercritical extract was dominated by (E)-caryophyllene (26.0%), γ-muurolene (22.0%), and caryophyllene oxide (8.1%)

    The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio

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    The A1Π−X1Σ+\textrm{A}^1\Pi-\textrm{X}^1\Sigma^+ band system of carbon monoxide, which has been detected in six highly redshifted galaxies (z=1.6−2.7z=1.6-2.7), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio (μ\mu) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X (vv,0) bands for v=0−9v=0-9 have been determined at an accuracy of Δλ/λ=1.5×10−7\Delta\lambda/\lambda=1.5 \times 10^{-7} through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the 3×10−83 \times 10^{-8} accuracy level, verifying the absorption data. Sensitivity coefficients KμK_{\mu} for a varying μ\mu have been calculated for the CO A-X bands, so that an operational method results to search for μ\mu-variation.Comment: 7 pages (main article), 3 figures, includes supplementary materia

    Search for varying constants of nature from astronomical observation of molecules

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    The status of searches for possible variation in the constants of nature from astronomical observation of molecules is reviewed, focusing on the dimensionless constant representing the proton-electron mass ratio μ=mp/me\mu=m_p/m_e. The optical detection of H2_2 and CO molecules with large ground-based telescopes (as the ESO-VLT and the Keck telescopes), as well as the detection of H2_2 with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope is discussed in the context of varying constants, and in connection to different theoretical scenarios. Radio astronomy provides an alternative search strategy bearing the advantage that molecules as NH3_3 (ammonia) and CH3_3OH (methanol) can be used, which are much more sensitive to a varying μ\mu than diatomic molecules. Current constraints are ∣Δμ/μ∣<5×10−6|\Delta\mu/\mu| < 5 \times 10^{-6} for redshift z=2.0−4.2z=2.0-4.2, corresponding to look-back times of 10-12.5 Gyrs, and ∣Δμ/μ∣<1.5×10−7|\Delta\mu/\mu| < 1.5 \times 10^{-7} for z=0.88z=0.88, corresponding to half the age of the Universe (both at 3σ\sigma statistical significance). Existing bottlenecks and prospects for future improvement with novel instrumentation are discussed.Comment: Contribution to Workshop "High Performance Clocks in Space" at the International Space Science Institute, Bern 201

    Cosmological evolution of the Higgs boson's vacuum expectation value

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    We point out that the expansion of the universe leads to a cosmological time evolution of the vacuum expectation of the Higgs boson. Within the standard model of particle physics, the cosmological time evolution of the vacuum expectation of the Higgs leads to a cosmological time evolution of the masses of the fermions and of the electroweak gauge bosons while the scale of Quantum Chromodynamics (QCD) remains constant. Precise measurements of the cosmological time evolution of u=me/mp, where me and mp are respectively the electron and proton mass (which is essentially determined by the QCD scale), therefore provide a test of the standard models of particle physics and of cosmology. This ratio can be measured using modern atomic clocks

    The Hyperlipidaemic Drug Fenofibrate Significantly Reduces Infection by SARS-CoV-2 in Cell Culture Models

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    The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has caused a significant number of fatalities and worldwide disruption. To identify drugs to repurpose to treat SARS-CoV-2 infections, we established a screen to measure the dimerization of angiotensin-converting enzyme 2 (ACE2), the primary receptor for the virus. This screen identified fenofibric acid, the active metabolite of fenofibrate. Fenofibric acid also destabilized the receptor-binding domain (RBD) of the viral spike protein and inhibited RBD binding to ACE2 in enzyme-linked immunosorbent assay (ELISA) and whole cell-binding assays. Fenofibrate and fenofibric acid were tested by two independent laboratories measuring infection of cultured Vero cells using two different SARS-CoV-2 isolates. In both settings at drug concentrations, which are clinically achievable, fenofibrate and fenofibric acid reduced viral infection by up to 70%. Together with its extensive history of clinical use and its relatively good safety profile, this study identifies fenofibrate as a potential therapeutic agent requiring an urgent clinical evaluation to treat SARS-CoV-2 infection
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