ThermInfo: Collecting, Retrieving, and Estimating Reliable Thermochemical Data

Standard enthalpies of formation are used for assessing the efficiency and safety of chemical processes in the chemical industry. However, the number of compounds for which the enthalpies of formation are available is many orders of magnitude smaller than the number of known compounds. Thermochemical data prediction methods are therefore clearly needed. Several commercial and free chemical databases are currently available, the NIST WebBook being the most used free source. To overcome this problem a cheminformatics system was designed and built with two main objectives in mind: collecting and retrieving critically evaluated thermochemical values, and estimating new data. In its present version, by using cheminformatics techniques, ThermInfo allows the retrieval of the value of a thermochemical property, such as a gas-phase standard enthalpy of formation, by inputting, for example, the molecular structure or the name of a compound. The same inputs can also be used to estimate data (presently restricted to non-polycyclic hydrocarbons) by using the Extended Laidler Bond Additivity (ELBA) method. The information system is publicly available a

Thermochemistry of the complexes Ti(η5-C5Me5)(C5Me4CH2) and Ti(η5-C5Me5)[C5Me3(CH2)2]

Reaction-solution calorimetric studies of the crystalline complexes Ti(n5-C5Me5)L (L = C5Me4CH2 or C5Me3(CH2)2) led to relative values of their standard enthalpies of formation. These data, together with early results obtained for several analogous TiIII complexes, enabled to discuss the energetics of two reactions of synthetic interest. The results are also used to analyse the possible bonding modes of ligands L to the titanium atom

O-H Bond dissociation enthalpies in hydroxyphenols. A time-resolved photoacoustic calorimetry and quantum chemistry studyy

Time-resolved photoacoustic calorimetry (TR-PAC) was used to investigate the energetics of O-H bonds of phenol, catechol, pyrogallol, and phloroglucinol. Values of À27.1 AE 3.9, À44.1 AE 4.4 and À1.6 AE 3.8 kJ mol À1 , respectively, were obtained for the solution-phase (acetonitrile) O-H bond dissociation enthalpies of the last three compounds relative to the O-H bond dissociation enthalpy in phenol, A value of 388.7 AE 3.7 kJ mol À1 was determined for the PhO-H bond dissociation enthalpy in acetonitrile. Density functional theory (MPW1PW91/aug-cc-pVDZ) calculations and complete basis set (CBS-4M) calculations were carried out to analyse intramolecular hydrogen bonding and to predict gas-phase O-H bond dissociation enthalpies, DH o (ArO-H). A microsolvation model, based on the DFT calculations, was used to study the differential solvation of the phenols and their radicals in acetonitrile and to bridge solution-and gas-phase data. The results strongly suggest that DDH o sln (ArO-H) % DDH o (ArO-H). Hence, to calculate absolute gas-phase O-H bond dissociation enthalpies in substituted phenols from the corresponding solution-phase values, the solvation enthalpies of the substituted phenols and their radicals are not required

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p<0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status