Tetrameric fluorophosphazene, (NPF(2))(4), planar or puckered?

The results obtained in a comprehensive experimental study on the redetermination of the structure of N(4)P(4)F(8) with single-crystal X-ray diffraction, gas electron diffraction (GED), and differential scanning calorimetry (DSC) establish clearly that, in contrast to the previous report, the eight-membered heterocycle is not planar. Above the phase transition temperature of -74 degrees C, the ring appears pseudoplanar. However, the N(4)P(4) ring is disordered and is puckered above the phase transition when the disorder is modeled correctly.

Vibrational spectra and gas phase structure of N-cyanoimidosulfurous difluoride, NCN=SF2.

The vibrational spectra, IR (gas) and Raman (liquid) of N-cyanoimidosulfurous difluoride, NCN=SF2, were recorded, and the molecular structure was determined by gas electron diffraction. The spectra were assigned by comparing the vibrational frequencies with those in related molecules and with calculated (HF, MP2, B3LYP with 6-31G(d) basis sets) values, and a normal coordinate analysis was performed. The molecule possesses a syn conformation (Ctriple bondN syn with respect to the bisector of the SF2 angle).

Effect on pancreatic blood flow and insulin output of infusions of aminophylline, galactose and galactose plus aminophylline into an isolated in situ portion of pancreas.

Effects on pancreatic blood flow and insulin output of infusions of aminophylline, galactose and galactose plus aminophylline were studied on an isolated portion of dog pancreas with only one afferent and one efferent blood vessel remaining. Infusion of aminophylline at 8 mg per minute gave significant increases in pancreatic blood flow and insulin output. Infusion of galactose at 7.

Effects of age and of fasting on the responsiveness of the insulin-secreting mechanism of the islets of Langerhans to glucose.

Insulin responsiveness to glucose of isolated islets of Langerhans was studied in 'younger' and 'older' rats after feeding and fasting for various lengths of time. In 'younger' rats, after prolonged fasting (168 h) the threshold for glucose-stimulated insulin secretion was increased. This was not evident in islets from 'younger' rats fasted for 48 or 89 h.

Insulin biosynthesis: the monoaminergic mechanisms and the specificity of "glucoreceptor".

Islets of Langerhans, isolated from the rat, did not synthesize insulin in the presence of L-glucose, fructose, galactose, 3-0-methyl glucose or sorbitol. A small amount of insulin was synthesized in the presence of glucosamine. Addition of caffeine to these compounds did not enhance the biosynthesis of insulin.