Bis(β-diketonato)- and allyl-(β-diketonato)-palladium(ii) complexes: synthesis, characterization and MOCVD application

Halogen-free allyl- and β-diketonate-functionalized Pd(ii) compounds were synthesized and successfully applied as MOVCD precursors for Pd and PdO thin film formation.

Readmission to the intensive care unit after cardiac surgery: a single-center experience with 7105 patients

AIM

Identification of patients at high risk for readmission to the Intensive Care Unit (ICU) after cardiac surgery is paramount. We evaluated the clinical characteristics of readmitted patients and identified perioperative prognostic variables for ICU readmission.

METHODS

A total of 7105 patients who underwent cardiac surgery between 2007 and 2010 and discharged after a primary stay in the ICU were reviewed retrospectively. Of these, 7.8% (554) patients were readmitted. The reasons for readmission and postoperative course were analyzed. Perioperative risk factors for readmission were determined by multivariate regression analysis.

RESULTS

Mortality of patients after readmission was 13.6% compared with 0.2% without recidivism (P<0.0001). Mean length of stay in hospital of patients requiring readmission was 24.9 ± 19.1 days and significantly longer compared to all other patients 12.3±8.4 days (P<0.0001). The main reasons for readmission were respiratory failure (39.0%) and cardiovascular instability (26.2%). Complex cardiac surgery, aortic surgery and extended stay in the ICU were the most powerful variables to predict ICU readmission.

CONCLUSION

ICU readmission was related to complex surgery and associated with impaired outcome. Respiratory complications were the most common reasons for readmission. Predictive renal and pulmonary risk factors indicate the need of preoperative preconditioning and patient selection.

[Cardiogenic shock]

Cardiogenic shock is most commonly a complication of acute myocardial infarction. The ischemic loss of functional myocardium triggers distinct cardiovascular responses which can deteriorate to global pump failure with a mortality rate of more than 50%. Causes of cardiogenic shock beyond myocardial ischemia are very diverse. Decisive management with rapid evaluation, identification of the underlying disease and urgent initiation of supportive measures as well as definitive therapy is of prognostic value. Causal treatment of the cardiac disease is crucial but has to be weighed against the specific surgical circumstances of perioperative patients, particularly concerning anticoagulation, platelet inhibition and bleeding risks. Hemodynamic stabilization is achieved by pharmacological support of myocardial function, control of arrhythmia and volume load. Prevention and intensive care of shock-related multiorgan failure is of pivotal importance in the successful management of cardiogenic shock.

Tip-enhanced near-field optical microscopy of carbon nanotubes

We review recent experimental studies on single-walled carbon nanotubes on substrates using tip-enhanced near-field optical microscopy (TENOM). High-resolution optical and topographic imaging with sub 15 nm spatial resolution is shown to provide novel insights into the spectroscopic properties of these nanoscale materials. In the case of semiconducting nanotubes, the simultaneous observation of Raman scattering and photoluminescence (PL) is possible, enabling a direct correlation between vibrational and electronic properties on the nanoscale. So far, applications of TENOM have focused on the spectroscopy of localized phonon modes, local band energy renormalizations induced by charge carrier doping, the environmental sensitivity of nanotube PL, and inter-nanotube energy transfer. At the end of this review we discuss the remaining limitations and challenges in this field.

Raman spectroscopy of graphene edges

Graphene edges are of particular interest since their orientation determines the electronic properties. Here we present a detailed Raman investigation of graphene flakes with edges oriented at different crystallographic directions. We also develop a real space theory for Raman scattering to analyze the general case of disordered edges. The position, width, and intensity of G and D peaks are studied as a function of the incident light polarization. The D-band is strongest for polarization parallel to the edge and minimum for perpendicular. Raman mapping shows that the D peak is localized in proximity of the edge. For ideal edges, the D peak is zero for zigzag orientation and large for armchair, allowing in principle the use of Raman spectroscopy as a sensitive tool for edge orientation. However, for real samples, the D to G ratio does not always show a significant dependence on edge orientation. Thus, even though edges can appear macroscopically smooth and oriented at well-defined angles, they are not necessarily microscopically ordered.