Time Correlation Function Modeling of Third-Order Sum Frequency Vibrational Spectroscopy of a Charged Surface/Water Interface.

Sum frequency vibrational spectroscopy (SFVS), a second-order optical process, is interface-specific in the dipole approximation [Perry, A.; Neipert, C.; Moore, P.; Space, B. Chem. Rev. 2006, 106, 1234-1258; Richmond, G. L. Chem. Rev. 2002, 102, 2693-2724; Byrnes, S. J.; Geissler, P. L.; Shen, Y. R. Chem. Phys. Lett. 2011, 516, 115-124]. At charged interfaces, the experimentally detected signal is a combination of enhanced second-order and static-field-induced third-order contributions due to the existence of a static field. Evidence of the importance/relative magnitude of this third-order contribution is seen in the literature [Ong, S.; Zhao, X.; Eisenthal, K. B. Chem. Phys. Lett. 1992, 191, 327-335; Zhao, X.; Ong, S.; Eisenthal, K. B. Chem. Phys. Lett. 1993, 202, 513-520; Shen, Y. R. Appl. Phys. B: Laser Opt. 1999, 68, 295-300], but a molecularly detailed approach to separately calculating the second- and third-order contributions is difficult to construct. Recent work presented a novel molecular dynamics (MD)-based theory that provides a direct means to calculate the third-order contributions to SFVS spectra at charged interfaces [Neipert, C.; Space, B. J. Chem. Phys. 2006, 125, 224706], and a hyperpolarizability model for water was developed as a prerequisite to practical implementation [Neipert, C.; Space, B. Comput. Lett. 2007, 3, 431-440]. Here, these methods are applied to a highly abstracted/idealized silica/water interface, and the results are compared to experimental data for water at a fused quartz surface. The results suggest that such spectra have some quite general spectral features.

Theoretical prediction of hydrogen-bond basicity pKBHX using quantum chemical topology descriptors.

Hydrogen bonding plays an important role in the interaction of biological molecules and their local environment. Hydrogen-bond strengths have been described in terms of basicities by several different scales. The pKBHX scale has been developed with the interests of medicinal chemists in mind. The scale uses equilibrium constants of acid···base complexes to describe basicity and is therefore linked to Gibbs free energy. Site specific data for polyfunctional bases are also available. The pKBHX scale applies to all hydrogen-bond donors (HBDs) where the HBD functional group is either OH, NH, or NH+. It has been found that pKBHX can be described in terms of a descriptor defined by quantum chemical topology, ΔE(H), which is the change in atomic energy of the hydrogen atom upon complexation. Essentially the computed energy of the HBD hydrogen atom correlates with a set of 41 HBAs for five common HBDs, water (r2=0.96), methanol (r2=0.95), 4-fluorophenol (r2=0.91), serine (r2=0.93), and methylamine (r2=0.97). The connection between experiment and computation was strengthened with the finding that there is no relationship between ΔE(H) and pKBHX when hydrogen fluoride was used as the HBD. Using the methanol model, pKBHX predictions were made for an external set of bases yielding r2=0.90. Furthermore, the basicities of polyfunctional bases correlate with ΔE(H), giving r2=0.93. This model is promising for the future of computation in fragment-based drug design. Not only has a model been established that links computation to experiment, but the model may also be extrapolated to predict external experimental pKBHX values.

A theoretical study of the sum frequency vibrational spectroscopy of the carbon tetrachloride/water interface.

Theoretical approximations to the sum frequency vibrational spectroscopy (SFVS) of the carbon tetrachloride/water interface are constructed using the quantum-corrected time correlation functions (TCF) to aid in interpretation of experimental data and to predict novel vibrational modes. Instantaneous normal mode (INM) methods are used to characterize the observed modes leading to the TCF signal, thus providing molecular resolution of the vibrational lineshapes. Detailed comparisons of the theoretical signals are made with those obtained experimentally and show excellent agreement for the spectral peaks in the O-H stretching region of water. An intermolecular mode, unique to the interface, at 848 cm(-1) is also identifiable, similar to the one seen for the water/vapor interface. INM analysis reveals the resonance is due to a wagging mode (hindered rotation) that was previously identified (Perry et al 2005 J. Chem. Phys. 123 144705) as localized on a single water molecule with both hydrogens displaced normal to the interface-generally it is found that the symmetry breaking at the interface leads to hindered translations and rotations at hydrophilic/hydrophobic interfaces that assume finite vibrational frequencies due to anchoring at the aqueous interface. Additionally, examination of the real and imaginary parts of the theoretical SFVS spectra reveal the spectroscopic species attributed the resonances and possible subspecies in the O-H region; these results are consistent with extant experimental data and associated analysis.

Requirements for trainee logbooks.

All trainees are required to keep a logbook as a record of the procedures they have carried out during their surgical training. However, the current logbook is only a record of work carried out and not of the outcome of the operations. It does not prepare the trainee for either a lifetime practice of surgical audit or for a lifetime of learning from the audit process. The logbook requirements of different training boards vary and consequently, trainees find the keeping of a logbook an inconsistent process with ill-defined learning objectives. The Royal Australasian College of Surgeons should define what needs to be collected, how data should be verified and how experience and learning should be reported, and should approve electronic databases that meet logbook standards. The choice of database software and format can then be left to the trainee. Although there are good examples of electronic logbooks being developed, there is, at present, no perfect logbook available. We recommend that all trainees, from the commencement of basic surgical training, should keep a logbook that contains the minimum and expanded datasets in addition to specific trainee data on supervision and learning. In addition to the current reporting format focused on procedural casemix and supervision level, quality/outcome reports and a record of learning are recommended.

Guidelines for surgical audit in Australia and New Zealand.

Surgical audit is an important part of the process to measure performance, reduce clinical risk and improve quality of care. Recognizing this, the Royal Australasian College of Surgeons established a Surgical Audit Taskforce as a subcommittee of the Board of Continuing Professional Standards. This study aims to review the recommendations of the Taskforce for data collection and peer review. The minimum data for whole-practice, continuing audit have been defined. The method of data collection, devices and databases are personal choices for the individual surgeon. However, there are many benefits of developing an electronic surgical audit, and these include facilitating comparison and sharing of audit data between units. Surgical audits should not only report on work carried out but also ensure that outcomes include key performance indicators such as major complications, readmissions, reoperations, transfers, incident reports, complaints and mortalities. Effective clinical governance demands that issues raised by audit need to be documented and reported together with recommendations for improvement. Surgeons should be proactive in helping to find and implement solutions to the issues arising from surgical audit.