Time resolved transient transmission spectroscopy of TiCl4 and SnCl4.

Herewith, for the first time, we present the vibrational spectra collected for liquid TiCl4 and liquid SnCl4 by use of time resolved transient transmission spectroscopy. Of our interest is the isotopically split isotropic ν1 intramolecular vibrational band, the shape of which is very sensitive to intermolecular interactions. The high resolution spectra, obtained as fast Fourier transforms of the time domain signals acquired in transient transmission experiment, are compared with spontaneous Raman spectra. The dependence of the spectrum shape on intermolecular interactions has been established by diluting TiCl4 and SnCl4 in CS2 at different concentrations. Fitting the simplified oscillatory model of a liquid to FFTs of time domain signals in transient transmission experiment we have found intermolecular force constants and decoherence lifetimes for all concentrations. Application of the pump-probe spectroscopic technique and windowed fast Fourier transform procedure allowed us to observe the evolution of the spectral shape, and thus of the intermolecular forces, after the liquid has been perturbed by the femtosecond pump pulse.

Fine structures in Raman spectra of tetrahedral tetrachloride molecules in femtosecond coherent spectroscopy.

Herewith, we present fast Fourier transforms of time resolved signals, obtained by use of the femtosecond transient transmission (TT) spectroscopy, for three tetrachlorides, CCl4, SiCl4, and GeCl4, and chloroform, CHCl3. Due to coherent excitation of molecules, the isotopic splitting of their spectral bands in the range of symmetric stretching vibration can be observed with high resolution not available in spontaneous Raman scattering. The intensity distribution in the isotopic fine structure pattern appears to differ for various studied molecules, which is explained by the role of intermolecular interactions and the local order of molecules in the liquids. In particular, in SiCl4, the vibrational band exhibits anomalous ratios of the peak amplitudes, which do not agree with the natural abundance of the isotopologues. Using the simple oscillatory model of the liquid and fitting theoretical curves to the experimental results, we have been able to find the intermolecular force constants for all three liquids and to formulate the conclusion that the anomalous spectral pattern in SiCl4 results from strong interactions between the closest Cl atoms belonging to adjacent molecules. Application of the windowed Fourier transform enables us to study the dynamics of intermolecular interactions. The strength of intermolecular interactions in CCl4, SiCl4, and GeCl4, found by the TT technique, is compared with the results obtained by means of the femtosecond optical Kerr effect spectroscopy.

External validation of the Revised Cardiac Risk Index and National Surgical Quality Improvement Program Myocardial Infarction and Cardiac Arrest calculator in noncardiac vascular surgery.

BACKGROUND: The National Surgical Quality Improvement Program Myocardial Infarction & Cardiac Arrest (NSQIP MICA) calculator and the Revised Cardiac Risk Index (RCRI) were derived using currently outdated methods of diagnosing perioperative myocardial infarctions. We tested the external validity of these tools in a setting of a systematic perioperative cardiac biomarker measurement. METHODS: Analysis of routinely collected data nested in the Vascular Events In Noncardiac Surgery Patients Cohort Evaluation Study. A consecutive sample of patients ≥45 yr old undergoing in-hospital noncardiac surgery in a single tertiary care centre was enrolled. The predictive performance of the models was tested in terms of the occurrence of major cardiac complications defined as a composite of a nonfatal myocardial infarction, a nonfatal cardiac arrest, or a cardiac death within 30 days after surgery. The plasma concentration of high-sensitivity troponin T was measured before surgery, 6-12 h after operation, and on the first, second, and third days after surgery. Myocardial infarction was diagnosed according to the Third Universal Definition. RESULTS: The median age was 65 (59-72) yr, and 704/870 (80.9%) subjects were male. The primary outcome occurred in 76/870 (8.7%; 95% confidence interval [CI], 6.9-10.8%) patients. The c-statistic was 0.64 (95% CI, 0.57-0.70) for the NSQIP MICA and 0.60 (95% CI, 0.54-0.65) for the RCRI. Predicted risks were systematically underestimated in calibration belts (P<0.001). The RCRI and the NSQIP MICA showed no clinical utility before recalibration. CONCLUSIONS: The NSQIP and RCRI models had limited predictive performance in this at-risk population. The recently updated version of the RCRI was more reliable than the original index.

The influence of interactions between isotopoloques on coherent, ultrafast vibrational dynamics of liquid C2Cl4.

The dynamics of intramolecular and intermolecular vibrations in liquid tetrachloroethylene are studied for the first time by use of femtosecond time-resolved techniques, such as transient transmission spectroscopy and optical Kerr effect spectroscopy. Fourier transforms of time signals are compared with spontaneous Raman spectra for both isotropic and anisotropic components. The isotopic effect resulting from natural abundance of chlorine isotopes manifests itself as splitting of the isotropic spectra of intramolecular symmetric vibrations. Application of windowed Fourier transform enables us to study the dynamics of both spectral responses in real time and to analyze the role of intermolecular interactions on the coherence in the system. In order to describe the dynamics of molecules in a liquid and to explain the experimental results, we use a simple theoretical model taking into account intermolecular interactions, which allowed us to find vibrational and rotational life times.

Altered preoperative coagulation and fibrinolysis are associated with myocardial injury after non-cardiac surgery.

BACKGROUND: Myocardial injury after non-cardiac surgery (MINS), a complication with unclear pathogenesis, occurs within the first 30 days after surgery and worsens prognosis. Hypercoagulability induced by surgery might contribute to plaque rupture, with subsequent thrombosis and myocardial injury. This study assessed haemostatic markers before surgery and evaluated their association with MINS. METHODS: This is a substudy of VISION, a prospective cohort study of perioperative cardiovascular events. Of 475 consecutive vascular surgery patients, 47 (9.9%) developed MINS, defined as postoperative high-sensitivity troponin ≥50 ng litre -1 , with ≥20% elevation from the preoperative concentration. The control group consisted of 84 non-MINS patients matched for patient characteristics and co-morbidities. The following preoperative markers of hypercoagulability and fibrinolysis were measured: antithrombin, factor VIII activity, von Willebrand factor concentration and activity, fibrinogen, D-dimer, plasmin-antiplasmin complex, and tissue plasminogen activator. Moreover, C-reactive protein and CD40L concentrations were measured to assess inflammatory activity. RESULTS: Patients with MINS compared with the non-MINS group had a significantly higher concentration of factor VIII (186 vs 155%, P =0.006), von Willebrand factor activity (223 vs 160%, P <0.001), von Willebrand factor concentration (317 vs 237%, P =0.02), concentrations of fibrinogen (5.6 vs 4.2 g litre -1 , P =0.03), D-dimer (1680.0 vs 1090.0 ng ml -1 , P =0.04), plasmin-antiplasmin complex (747 vs 512 ng ml -1 , P =0.002) and C-reactive protein (10 vs 4.5 mg litre -1 , P =0.02) but not antithrombin (95 vs 94%, P =0.89), tissue plasminogen activator (11 vs 9.7 ng ml -1 , P =0.06) and CD40L (8790 vs 8580 pg ml -1 , P =0.73). CONCLUSIONS: Preoperative elevation of blood markers of hypercoagulability in patients undergoing vascular surgery is associated with a higher risk of MINS. CLINICAL TRIAL REGISTRATION: NCT00512109.

Femtosecond optical Kerr effect setup with signal "live view" for measurements in the solid, liquid, and gas phases.

We present the experimental setup constructed in our laboratory for measurement of the femtosecond optical Kerr effect. The setup allows measurements with high temporal resolution and acquisition speed. The high signal to noise ratio is obtained with use of a homemade balanced detector. Due to the high acquisition speed and good signal to noise ratio, it is possible to have a "live view" of the signal and to easily tune the sample position and orientation before the measurement. We show the example results obtained in the solid, liquid, and the gas phases and we use them in order to check on the precision of our setup. As the samples we have used a YAG crystal, liquid acetone, and atmospheric air. In the latter two cases, a good agreement with the literature data has been found. The measurements in the gas phase confirm that our setup, although utilizing low energy pulses from the sapphire oscillator, is able to acquire high quality rotational signal in a low density sample.