RESUMO
Accurate equilibrium structures have been determined for (Z)-pent-2-en-4-ynenitrile (8) and maleonitrile (9) by combining microwave spectroscopy data and ab initio quantum chemistry calculations. The microwave spectra of 10 isotopomers of 8 and 5 isotopomers of 9 were obtained using a pulsed nozzle Fourier transform microwave spectrometer. The ground-state rotational constants were adjusted for vibration-rotation interaction effects calculated from force fields obtained from ab initio calculations. The resultant equilibrium rotational constants were used to determine structures that are in very good agreement with those obtained from high-level ab initio calculations (CCSD(T)/cc-pVTZ). The geometric parameters in 8 and 9 are very similar; they also do not differ significantly from the all-carbon analogue, (Z)-hex-3-ene-1,5-diyne (7), the parent molecule for the Bergman cyclization. A small deviation from linearity about the alkyne and cyano linkages is observed for 7-9 and several related species where accurate equilibrium parameters are available. The data on 7-9 should be of interest to radioastronomy and may provide insights on the formation and interstellar chemistry of unsaturated species such as the cyanopolyynes.
RESUMO
A ten year community hospital experience of 124 patients with ductal adenocarcinoma of the pancreas proved at biopsy is reported. All patients underwent a celiotomy, and 94 per cent were observed until death. All of the patients were stratified by stage (I, 9 per cent; II, 30 per cent; III, 18 per cent, and IV, 43 per cent). Nine of the patients with Stage I disease underwent resection with a high postoperative mortality rate of 44 per cent and only one five year survivor. Fifty-nine patients with Stages II and III disease underwent biliary bypass with a low postoperative mortality rate of 2 per cent. Bypass of the common bile duct (N = 24) provided more permanent palliation against recurrent jaundice or cholangitis (p less than 0.05), but did not improve the survival time when compared with bypass of the gallbladder (N = 20). This was not true for those with Stage IV disease in whom recurrent jaundice did not develop in those with either bypass of the gallbladder or common duct. Adding prophylactic gastroenterostomy (GE) to biliary bypass (N = 25) conferred no survival benefit, but did protect against subsequent duodenal obstruction (p less than 0.05). Thirty-seven per cent of the 38 patients in whom a GE was not performed had duodenal obstruction develop. Adjuvant radiation and chemotherapy in 22 patients with unresectable Stages II and III disease resulted in a significant prolongation of survival time compared with 15 untreated patients in the control group (p less than 0.05). Fifty-one patients with Stage IV disease underwent biliary bypass or biopsy of the tumor resulting in a 14 per cent postoperative mortality rate and a median survival time of four months. Nine per cent of the 44 survivors with Stage IV disease lived at least one year. The implications of these findings to clinical practice are discussed.
