Rotational Spectrum, Structure, and Quadrupole Coupling of Cyclopropylchloromethyldifluorosilane

Cyclopropylchloromethyldifluorosilane, C-C3H5SiF2CH2Cl, Has Been Synthesized, and its Rotational Spectrum Has Been Recorded by Chirped-Pulse Fourier Transform Microwave Spectroscopy. the Spectral Analysis of Several Isotopologues Indicates the Presence of Two Distinct Conformations in the Free-Jet Expansion, Which Are Interconvertible through a Rotation of the Chloromethyl Group. a Partial Substitution Structure is Presented for the Lower Energy Conformation and is Compared to the Equilibrium Structure Obtained from Quantum Chemical Calculations. Additionally, the Presence of the Chlorine Nucleus Leads to the Rotational Transitions Splitting into Multiple Hyperfine Components and Χaa, a Measure of the Electric Field Gradient Along the a Axis, is Unusually Small at Merely +0.1393(73) MHz. Various Common Ab Initio and Density Functional Theory Methods Fail to Predict Good Quadrupole Coupling Constants (In the Principal Axis System) that Adequately Reproduce the Observed Hyperfine Splitting, Although Diagonalizing the Quadrupole Coupling Tensor from the Principal Axis System into a Nucleus-Centered Axis System Reveals that, overall, These Methods Calculate Reasonably the Electric Field Gradient About the Chlorine Nucleus. Finally, a Total of Nine Electric Dipole Forbidden, Quadrupole Allowed Transitions Are Observed in the Rotational Spectra of the Parent Species of the Higher Energy Conformation and the 37Cl Isotopologue of the Lower Energy Conformation. These Include Those of X-Type (No Change in Parity of Ka or Kc), Which, to Our Knowledge, is the First Time Such Transitions Have Been Observed in a Chlorine-Containing Molecule

Efficacy of Losartan in Hospitalized Patients With COVID-19-Induced Lung Injury: A Randomized Clinical Trial

Importance: SARS-CoV-2 viral entry may disrupt angiotensin II (AII) homeostasis, contributing to COVID-19 induced lung injury. AII type 1 receptor blockade mitigates lung injury in preclinical models, although data in humans with COVID-19 remain mixed. Objective: To test the efficacy of losartan to reduce lung injury in hospitalized patients with COVID-19. Design, Setting, and Participants: This blinded, placebo-controlled randomized clinical trial was conducted in 13 hospitals in the United States from April 2020 to February 2021. Hospitalized patients with COVID-19 and a respiratory sequential organ failure assessment score of at least 1 and not already using a renin-angiotensin-aldosterone system (RAAS) inhibitor were eligible for participation. Data were analyzed from April 19 to August 24, 2021. Interventions: Losartan 50 mg orally twice daily vs equivalent placebo for 10 days or until hospital discharge. Main Outcomes and Measures: The primary outcome was the imputed arterial partial pressure of oxygen to fraction of inspired oxygen (Pao2:Fio2) ratio at 7 days. Secondary outcomes included ordinal COVID-19 severity; days without supplemental o2, ventilation, or vasopressors; and mortality. Losartan pharmacokinetics and RAAS components (AII, angiotensin-[1-7] and angiotensin-converting enzymes 1 and 2)] were measured in a subgroup of participants. Results: A total of 205 participants (mean [SD] age, 55.2 [15.7] years; 123 [60.0%] men) were randomized, with 101 participants assigned to losartan and 104 participants assigned to placebo. Compared with placebo, losartan did not significantly affect Pao2:Fio2 ratio at 7 days (difference, -24.8 [95%, -55.6 to 6.1]; P = .12). Compared with placebo, losartan did not improve any secondary clinical outcomes and led to fewer vasopressor-free days than placebo (median [IQR], 9.4 [9.1-9.8] vasopressor-free days vs 8.7 [8.2-9.3] vasopressor-free days). Conclusions and Relevance: This randomized clinical trial found that initiation of orally administered losartan to hospitalized patients with COVID-19 and acute lung injury did not improve Pao2:Fio2 ratio at 7 days. These data may have implications for ongoing clinical trials. Trial Registration: ClinicalTrials.gov Identifier: NCT04312009

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

RAMAN AND INFRARED SPECTRA, CONFORMATIONAL STABILITY AND BARRIERS TO INTERNAL ROTATION OF 3–BROMO-2-METHYLPROPENE

Author Institution: Department of Chemistry and Biochemistry, University of South Carolina; Department of Chemistry, University of Missouri-Kansas CityThe Raman (3200 to $20 cm^{-1})$ and infrared (3200 to $35 cm^{-1}$) spectra of 3-bromo-2-methylpropene, $H_{2}C=C(CH_{3}) CH_{2}Br$, have been recorded for the gas and solid. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values obtained. The fundamental asymmetric torsional mode for the {gauche} conformer is observed at $81.5 cm^{-1}$ with one excited state falling at a lower frequency but the asymmetric torsion is not observed for the higher energy {s-cis} conformer. Utilizing the {gauche} observed torsional frequencies, the {gauche} dihedral angle, the enthalpy difference between conformers, and the calculated torsional fundamental frequency for the {s-cis} conformer, the potential function governing the interconversion of the rolamers has been estimated. This potential function gives values of $170 cm^{-1}$ (486 cal/mol), $2659 cm^{-1}$ (7.60 kcal/mol), and $725 cm^{-1}$ (2.07 kcal/mol), for the {s-cis} to {gauche, gauche to gauche}, and {gauche} to {s-cis} barriers, respectively, and it is compared to that obtained with the $RHF/STO-3G^{*}$ basis set. From the methyl torsional frequency of $172 cm^{-1}$ for the {gauche} conformer, the threefold barrier of $695 cm^{-1}$ (1.99 Kcal/mol) has been calculated for the methyl group. A complete vibrational assignment is proposed on Raman depolarization data, group frequencies, and relative infrared and Raman intensities. The conformational energy difference and optimized geometries of both conformers have also been obtained form {ab initio} calculations

VIBRATIONAL SPECTRA AND ASSIGNMENTS, CONFORMATIONAL STABILITY. STRUCTURE AND AB INITIO CALCULATIONS OF 2-METHYLPROPANAL AND 2-METHYLPROPANAL-d7d_{7}

Author Institution: Department of Chemistry, University of South Carolina; Mobay Chemical Corporation, Analytical Research Laboratory, CharlestonThe infrared spectra $(3600 to 50 cm^{-1})$ of the gaseous and solid states, and the Raman spectra (3600 to $10 cm^{-1})$ of the gaseous, liquid and solid states of 2-methylpropanal (isobutyraldehyde). $(CH_{3})_{2}CHCHO$, and the corresponding deuterium compound, $(CD_{3})_{2}CDCHO$, have been recorded. Additionally, qualitative depolarization ratios have been obtained from the Raman spectra of the liquids. These data have been interpreted for the fluid phases on the basis that the gauche conformation (oxygen atom eclipsing a methyl group) is thermodynamically preferred over the high energy trans conformation (oxygen atom eclipsing the secondary hydrogen) and is the only rotamer present in the spectra of the annealed solids. From the relative intensities of the Raman lines of the liquid at $633 cm^{-1}$ (gauche) and $551 cm^{-1}$ (trans) as a function of temperature, the energy difference is found to be $440 \pm 17 cm^{-1} (1.26 \pm 0.05 kcal/mol)$. A complete vibrational assignment is proposed which is based on infrared band contours, depolarization values, isotopic shifts and group frequencies. The vibrational frequencies determined from experiment will be compared to the corresponding quantities obtained from ab initio Hartree-Fock gradient calculations employing the 3-21G and $6-31G^{\ast}$ basis sets. Additionally, structural parameters previously provided will be compared to those determined from ab initlo methods