The Entropy of Dimethyl Acetylene from Low Temperature Calorimetric Measurements. Free Rotation in the Dimethyl Acetylene Molecule

The separation of the methyl groups in the dimethyl acetylene molecule, H3C-C≡C-C-CH3, is much greater than it is in ethane, and if the potential barrier [1] of about 3000 cal./mole restricting internal rotation in the latter is due to interactions between the methyl groups, then this barrier should be much smaller in dimethyl acetylene. If, on the other hand, the restricting potential in ethane is largely due to resonance with double bonded structures as proposed by Gorin, Walter, and Eyring [2], that fact that the length of the C-C single bonds in dimethyl acetylene [3] is such as to indicate considerable double bond character might lead one to expect a barrier about as large as in ethane. In order to determine the magnitude of this barrier we have calculated the entropy of dimethyl acetylene from low temperature calorimetric measurements and have compared this experimental value with that computed from molecular data

Uranium Monosulfide. The Ferromagnetic Transition. The Heat Capacity and Thermodynamic Properties from 1.5° to 350°K

The heat capacity of uranium monosulfide was measured from 1.5° to 22°K by an isothermal (isoperibol) method and from 6° to 350°K by an adiabatic technique. The ferromagnetic transition at 180.1°K has a characteristic lambda shape and associated magnetic ordering entropy and enthalpy increments of 1.62 ± 0.2 cal °K−1mole−1 and 231 ± 20 cal mole−1, respectively, over the temperature range 0° to 230°K. The correlation of the thermal data with magnetic studies is discussed. The heat capacity below 9°K is represented by Cp  =  5.588 × 10−3T + 2.627 × 10−4T3 / 2 + 6.752 × 10−5T3cal°K−1mole−1Cp=5.588×10−3T+2.627×10−4T3∕2+6.752×10−5T3cal°K−1mole−1, in which the successive terms represent conduction electronic, magnetic, and lattice contributions. Values of the entropy [S°], enthaply function [(H° − H°0) / T][(H°−H°0)∕T], and Gibbs‐energy function [(G° − H°0) / T][(G°−H°0)∕T] are 18.64 ± 0.005, 8.94 ± 0.002, and − 9.70 ± 0.02 cal °K−1 mole−1, respectively, at 298.15°K. The Gibbs energy of formation at 298.15°K is − 72.9 ± 3.5 kcal mole−1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70623/2/JCPSA6-48-1-155-1.pd

The Entropy of Dimethyl Sulfide from Low Temperature Calorimetric Measurements. Restricted Rotation of the Methyl Groups

In order to arrive at a satisfactory theory for the potential restricting the rotation of methyl groups in many molecules, it is desirable to determine how the magnitude of the barrier depends on the kind of atom to which the methyl groups are bonded. Recently we have obtained an estimate of the barriers in dimethyl sulfide by comparing the entropy obtained from calorimetric measurements extending to low temperatures with that computed from molecular data

Thermodynamics of the Lanthanide Trifluorides. I. The Heat Capacity of Lanthanum Trifluoride, LaF₃ from 5 to 350°K and Enthalpies from 298 to 1477°K

The heat capacity of a sample of LaF3 was determined in the temperature range 5-350°K by aneroid adiabatic calorimetry and the enthalpy from 298.15 to 1477°K by drop calorimetry. The heat capacity at constant pressure C°p(298.15°K), the entropy S°(298.15°K), the enthalpy [H°(298.15°K)-H°(0)] and the Planck function -[G°(298.15°K)-H°(0)]/298.15°K; were found to be (90.29±0.09) J °K-1·mole-1, (106.98±0.11) J °K-1·mole-1, (16717±17) J mole-1, and (50.91±0.05) J °K -1·mole-1. The thermal functions from the present research were extended up to the melting temperature (1766°K) by combination with previously published results. The anomalously high heat capacity from about 1100 to 1766°K is discussed

Specific heat of apiezon T grease from 1 to 350[deg] K

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33364/1/0000762.pd

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Dimanganese Phosphide, Mn₂P: Heat Capacity from 5 to 350 K, Magnetic Entropy, and Thermodynamic Functions to 1300 K

The heat capacity of a sample of Mn2P was determined in the temperature range 5 to 350 K by aneroid adiabatic calorimetry. A small peak in the heat capacity correlated with the antiferromagnetic ordering of the compound was found at (102.5 ± 0.5) K. The associated magnetic entropy was calculated to be (9.43 ± 0.52) J K-1 mol-1. The heat capacity at constant pressure Cp o(298,15 K), the entropy So(298.15 K), the enthalpy {Ho(298.15 K) - Ho(0)}, and the function {Go(298.15 K) - Ho(0)} 298.15 K were found to be (73.54 ± 0.22) J K-1 mol-1, (91.01 ± 0.27) J K-1 mol-1, (14037 ± 42) J mol-1, and -(43.93 ± 0.13) J K-1 mol-1, respectively. Values of these functions at selected temperatures up to 1300 K are presented in tabular form. The coefficient γ for the contribution of the conduction electrons to the heat capacity (γT) was found to be (23.7 ± 1.6) mJ K-2 mol-1