Near-Infrared Spectroscopy and Anharmonic Theory of Protonated Water Clusters: Higher Elevations in the Hydrogen Bonding Landscape.

Near-infrared spectroscopy measurements are presented for protonated water clusters, H+(H2O) n, in the size range of n = 1-8. Clusters are produced in a pulsed-discharge supersonic expansion, mass selected, and studied with infrared laser photodissociation spectroscopy in the regions of 3600-4550 and 4850-7350 cm-1. Although there is some variation with cluster size, the main features of these spectra are a broad absorption near 5300 cm-1, a sharp doublet near 7200 cm-1, as well as a structured absorption near 4100 cm-1 for n ≥ 2. The vibrational patterns measured for the hydronium, Zundel, and Eigen ions are compared to those predicted by different forms of anharmonic theory. Second-order vibrational perturbation theory (VPT2) and a local mode treatment of the OH stretches both capture key aspects of the spectra but suffer understandable deficiencies in the quantitative description of band positions and intensities.

Infrared spectroscopy and theory of the formaldehyde cation and its hydroxymethylene isomer.

Pulsed discharges in supersonic expansions containing the vapor of different precursors (formaldehyde, methanol) produce the m/z = 30 cations with formula [H2,C,O]+. The corresponding [H2,C,O]+ Ar complexes are produced under similar conditions with argon added to the expansion gas. These ions are mass selected in a time-of-flight spectrometer and studied with infrared laser photodissociation spectroscopy. Spectra in the 2300-3000 cm-1 region produce very different vibrational patterns for the ions made from different precursors. Computational studies with harmonic methods and various forms of anharmonic theory allow detailed assignment of these spectra to two isomeric species. Discharges containing formaldehyde produce primarily the corresponding formaldehyde radical cation, CH2O+, whereas those with methanol produce exclusively the cis- and trans-hydroxymethylene cations, HCOH+. The implications for the interstellar chemistry of these cations are discussed.

Validation of a Crowdsourcing Methodology for Developing a Knowledge Base of Related Problem-Medication Pairs.

BACKGROUND: Clinical knowledge bases of problem-medication pairs are necessary for many informatics solutions that improve patient safety, such as clinical summarization. However, developing these knowledge bases can be challenging. OBJECTIVE: We sought to validate a previously developed crowdsourcing approach for generating a knowledge base of problem-medication pairs in a large, non-university health care system with a widely used, commercially available electronic health record. METHODS: We first retrieved medications and problems entered in the electronic health record by clinicians during routine care during a six month study period. Following the previously published approach, we calculated the link frequency and link ratio for each pair then identified a threshold cutoff for estimated problem-medication pair appropriateness through clinician review; problem-medication pairs meeting the threshold were included in the resulting knowledge base. We selected 50 medications and their gold standard indications to compare the resulting knowledge base to the pilot knowledge base developed previously and determine its recall and precision. RESULTS: The resulting knowledge base contained 26,912 pairs, had a recall of 62.3% and a precision of 87.5%, and outperformed the pilot knowledge base containing 11,167 pairs from the previous study, which had a recall of 46.9% and a precision of 83.3%. CONCLUSIONS: We validated the crowdsourcing approach for generating a knowledge base of problem-medication pairs in a large non-university health care system with a widely used, commercially available electronic health record, indicating that the approach may be generalizable across healthcare settings and clinical systems. Further research is necessary to better evaluate the knowledge, to compare crowdsourcing with other approaches, and to evaluate if incorporating the knowledge into electronic health records improves patient outcomes.

Infrared spectroscopy of the methanol cation and its methylene-oxonium isomer.

The carbenium ion with nominal formula [C,H4,O](+) is produced from methanol or ethylene glycol in a pulsed-discharge supersonic expansion source. The ion is mass selected, and its infrared spectrum is measured from 2000 to 4000 cm(-1) using laser photodissociation spectroscopy and the method of rare gas atom tagging. Computational chemistry predicts two isomers, the methanol and methylene-oxonium cations. Predicted vibrational spectra based on scaled harmonic and reduced dimensional treatments are compared to the experimental spectra. The methanol cation is the only isomer produced when methanol is used as a precursor. When ethylene glycol is used as the precursor, methylene-oxonium is produced in addition to the methanol cation. Theoretical results at the CCSD(T)/cc-pVTZ level show that methylene-oxonium is lower in energy than methanol cation by 6.4 kcal/mol, and is in fact the global minimum isomer on the [C,H4,O](+) potential surface. Methanol cation is trapped behind an isomerization barrier in our source, providing a convenient method to produce and characterize this transient species. Analysis of the spectrum of the methanol cation provides evidence for strong CH stretch vibration/torsion coupling in this molecular ion.

State of the art in clinical informatics: evidence and examples.

OBJECTIVE: The field of clinical informatics has expanded substantially in the six decades since its inception. Early research focused on simple demonstrations that health information technology (HIT) such as electronic health records (EHRs), computerized provider order entry (CPOE), and clinical decision support (CDS) systems were feasible and potentially beneficial in clinical practice. METHODS: In this review, we present recent evidence on clinical informatics in the United States covering three themes: 1) clinical informatics systems and interventions for providers, including EHRs, CPOE, CDS, and health information exchange; 2) consumer health informatics systems, including personal health records and web-based and mobile HIT; and 3) methods and governance for clinical informatics, including EHR usability; data mining, text mining, natural language processing, privacy, and security. RESULTS: Substantial progress has been made in demonstrating that various clinical informatics methodologies and applications improve the structure, process, and outcomes of various facets of the healthcare system. CONCLUSION: Over the coming years, much more will be expected from the field. As we move past the "early adopters" in Rogers' diffusion of innovations' curve through the "early majority" and into the "late majority," there will be a crucial need for new research methodologies and clinical applications that have been rigorously demonstrated to work (i.e., to improve health outcomes) in multiple settings with different types of patients and clinicians.

Infrared spectroscopy of the mass 31 cation: protonated formaldehyde vs methoxy.

Pulsed discharges containing methanol or ethanol produce ions having the nominal formula [C,H(3),O](+), i.e. m/z = 31. Similar ions resulting from electron impact ionization in mass spectrometers are long recognized to have either the CH(2)OH(+) protonated formaldehyde or CH(3)O(+) methoxy cation structures. The H(2)OCH(+) oxonio-methylene structure has also been suggested by computational chemistry. To investigate these structures, ions are expanded in a supersonic beam, mass-selected in a time-of-flight spectrometer, and studied with infrared laser photodissociation spectroscopy. Sharp bands in the O-H and C-H stretching and fingerprint regions are compared to computational predictions for the three isomeric structures and their vibrational spectra. Protonated formaldehyde is the most abundant isomer, but methoxy is also formed with significant abundance. The branching ratio of these two ion species varies with precursors and formation conditions.

IR spectroscopy and theory of Cu+(H2O)Ar2 and Cu+(D2O)Ar2 in the O-H (O-D) stretching region: fundamentals and combination bands.

Copper-water ion-molecule complexes with attached argon atoms, Cu(+)(H(2)O)Ar(2), are produced in a supersonic molecular beam by pulsed laser vaporization. These systems are mass-selected in a reflectron time-of-flight spectrometer and studied with infrared photodissociation spectroscopy. The vibrational spectra for these complexes are characteristic of many cation-water systems, exhibiting symmetric and asymmetric O-H stretch fundamentals, and weaker features at higher frequency that have been tentatively assigned to combination bands. Using isotopically substituted spectra and model potential calculations, we are able to assign the combination bands to a water torsional vibration (frustrated rotation) in combination with the asymmetric stretch fundamental. This combination band assignment is likely to apply to IR spectra of many cation-water complexes.

Quantum/classical studies of photodissociation and reaction dynamics in clusters.

In this paper, a multiple configurational time-dependent self-consistent field (TDSCF) approach for studying photodissociation and reaction dynamics is described. This approach has been applied to studies of several benchmark systems and is found to provide an accurate description of the reactions. The focus of the present work is on investigations of processes in cluster environments. Specifically, the dynamics of the O(3P) + HCl reaction and H2O photodissociation dynamics in isolation and in Van der Waals complexes with one argon atom are compared. The nature and importance of quantum mechanical effects in these systems are investigated through an analysis of the results of the quantum/classical simulations and a comparison of these results with those obtained from previously reported experimental and classical studies on these systems. It is found that, although the effects of complexation are subtle, they are not negligible. In addition, most of them can be understood in terms of kinematic and steric factors, although electronic effects cannot be dismissed.