The melting temperatures and phase structures of a series of hydrogenated polybutadienes with fixed co-unit content (2.3 mol % branch points) and varying molecular weights have been studied. These copolymers represent molecular weight and composition fractions of randomly ethyl-branched ethylene copolymers. Also studied were a set of random ethylene-hexene copolymers with a lower co-unit content. The observed melting temperatures, after a variety of crystallization procedures, were found to decrease with increasing molecular weight for both copolymer types. This unusual result could be attributed to the decreasing crystallite thickness in the chain direction with molecular weight. At the higher molecular weights, M = 4.6 X 10®, the crystallite thickness is reduced to about 30 A. Associated with the crystallite is a relatively large disordered overlayer. Although small-angle X-ray measurements and thin-section transmission electron microscopy give results that are in quantitative agreement for the crystallite thickness, the Raman LAM measurement give significantly higher values in the low-size range. The conventional extrapolative method of plotting the observed melting temperature against the crystallization temperature, in order to obtain the equilibrium melting temperature, failed for the random copolymers at low levels of crystallinity. A straight line resulted that paralleled the 45°line. Therefore, extrapolation to the equilibrium melting temperature could not be accomplished. Although the extrapolation could be made for higher levels of crystallinity, this procedure was arbitrary and lead to unreasonable values for the equilibrium melting temperature.

BACKGROUND Neurologic complications (NCs) are the major adverse events after left ventricular assist device (LVAD) surgery. Pre-operative and post-operative factors associated with NCs in patients with LVADs were investigated. METHODS We reviewed 307 consecutive patients undergoing LVAD surgery (167 HeartMate I and 140 HeartMate II devices) at Columbia University Medical Center between November 2000 and December 2010. Clinical characteristics and hemodynamic and laboratory indexes were analyzed. NC was defined according to the Interagency Registry for Mechanically Assisted Circulatory Support definition of neurologic dysfunction, including transient ischemic attack (TIA) and ischemic or hemorrhagic cerebrovascular accident (CVA). RESULTS NCs developed in 43 patients (14.0%) at 91.8 ± 116.3 days post-operatively. The frequency of NC development was similar in HeartMate I and II patients. Patients with NC showed a higher frequency of pre-LVAD CVA history (27.9% vs 15.5%, p = 0.046), lower pre-operative sodium (129.0 ± 7.0 vs 132.1 ± 8.1 mg/dl, p = 0.018) and albumin concentrations (3.5 ± 0.7 vs 3.7 ± 0.6 mg/dl, p = 0.049), lower post-operative hematocrit (34.9% ± 5.1% vs 37.8% ± 6.1%, p = 0.0034), sodium (131.6 ± 7.7 vs 134.4 ± 6.4 mg/dl, p = 0.010) and albumin concentrations (3.7 ± 0.5 vs 3.9 ± 0.5 mg/dl, p = 0.0016), and higher frequency of post-operative infection (39.5% vs 19.3%, p = 0.003) than those without NC. Multiple regression analysis revealed that CVA history (odds ratio, 2.37, 95% confidence interval, 1.24 –5.29; p = 0.011) and post-operative infection (odds ratio, 2.99, 95% confidence interval, 1.16 –10.49; p = 0.011) were highly associated with NC development. The combination of CVA history, pre-operative and post-operative sodium and albumin, and post-operative hematocrit and infection could discriminate patients developing NCs with a probability of 76.6%. CONCLUSIONS Previous stroke, persistent malnutrition and inflammation, severity of heart failure, and post-LVAD infections are key factors associated with development of NCs after LVAD implantation.

This preoperative 3-dimensional computed tomography analysis of segmental anatomy can confirm the tumor location within an anatomic segment and aid in predicting surgical margins. This 3-dimensional computed tomography information may assist in the preoperative assessment regarding the suitability of segmentectomy for peripheral lung cancers.

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AA is a common occurrence after LTx, occurring with greatest frequency in the first postoperative week, and results in a significant reduction in long-term survival. Increasing age and before coronary artery bypass grafting were identified as independent risk factors for AA development. Better understanding of these risk factors may improve identification of patients at heightened risk after transplantation.