Bibliothek

Notizen: [Auszug] WHILE investigating a manganese-activated zinc silicate, we have found that the temperature-dependence of the dielectric losses and that of the fluorescence (2537 A. excitation) show an intricate connexion. In the accompanying graph there is plotted the logarithm of the total number of light ...

Notizen: Abstract We report five patients with moyamoya associated with arterial anomalies, including five aneurysms, one with ectasia of the parent artery, a basilar artery fenestration and an arteriovenous malformation. Possible pathogenetic factors for moyamoya are discussed, and a prenatal origin is suggested.

Notizen: Abstract A mixing model is coupled with fermentation kinetics in order to simulate a fermentation as a function of mixing conditions and scale-up. The mixing model for a batch stirred tank with three stirrers consists of three regions, each of them characterized by an ideally mixed compartment around the stirrer and two macromixers, i.e. cascades of tank-in-series, describing the recirculation flow. The model contains four parameters — radial and axial circulation time, volume of the ideally mixed stirrer compartment and the number of tanks in each cascade. These values, determined by Mayr et al. in function of the operational conditions and scale-up, were choosen to simulate the fermentation of glutamic acid to show the pH-fluctuation at different control and scale conditions. By choosing optimal regulation properties, such as input flow rate and/or concentration of the base, regulation span, position of the pH-electrode and base input location, etc., fluctuations of the pH-value in the bio-reactor can be minimized. However, the negative effect of insufficient mixing conditions can be reduced only by an increasing number of the base input places. In large scale fermentors, the axial circulation time is rather high, about 5–10 times larger than the radial one. This might result in a large amplitude of the pH-fluctuation. As it is shown, using an input place for base in each stirrer region, the negative impact of the insufficient axial mixing on the fermentation can be diminished perfectly. In this case ammonia should be fed into the reactor as an aqueous solution.

Notizen: Abstract An aorto-duodenal fistula, an infrequent complication of abdominal aortic aneurysm, was diagnosed on the basis of characteristic CT findings: signs of leakage of the aneurysm, blood-filled duodenum and jejunum, and small gas collections within the wall of the aneurysm. The role of imaging techniques in the diagnosis is discussed and the importance of dynamic contrast-enhanced CT is emphasized.

Notizen: Abstract Heart rate changes were measured as a psychophysiological indicator during grasping reflex in 27 full-term healthy newborns at 2.5–50 h after birth. A significant heart rate deceleration accompanied the grasping response. Conclusion Reflex grasping of a mother's hand, as a component of human attachment behaviour, may have a positive calming effect on the infant's state and could have therapeutic value for high risk mother-infant dyads.

Notizen: Abstract Bleeding from the suprahepatic inferior vena cava (IVC) was encountered in a patient undergoing repeat liver resection for the fourth time due to a recurrence of colorectal liver metastases. Bleeding was observed from an IVC tear above the liver and it was not possible to control it with traditional clamping procedures including total vascular exclusion (a suprahepatic clamp). Hypothermia, cardioplegia, and circulatory arrest were all required to control the bleeding. The inferior vena cava was reconstructed with a pericardial patch. The patient recovered well and was discharged on the 14th postoperative day.

Notizen: Abstract  A mixing model is coupled with fermentation kinetics in order to simulate a fermentation as a function of mixing conditions and scale-up. The mixing model for a batch stirred tank with three stirrers consists of three regions, each of them characterized by an ideally mixed compartment around the stirrer and two macromixers, i.e. cascades of tank-in-series, describing the recirculation flow. The model contains four parameters – radial and axial circulation time, volume of the ideally mixed stirrer compartment and the number of tanks in each cascade. These values, determined by Mayr et al. in function of the operational conditions and scale-up, were choosen to simulate the fermentation of glutamic acid to show the pH-fluctuation at different control and scale conditions. By choosing optimal regulation properties, such as input flow rate and/or concentration of the base, regulation span, position of the pH-electrode and base input location, etc., fluctuations of the pH-value in the bio-reactor can be minimized. However, the negative effect of insufficient mixing conditions can be reduced only by an increasing number of the base input places. In large scale fermentors, the axial circulation time is rather high, about 5–10 times larger than the radial one. This might result in a large amplitude of the pH-fluctuation. As it is shown, using an input place for base in each stirrer region, the negative impact of the insufficient axial mixing on the fermentation can be diminished perfectly. In this case ammonia should be fed into the reactor as an aqueous solution. Nomenclature F m3/s liquid flow rate F G m3/s separate gas flow rate F Gax, FGrad m3/s gas flow rate joint with liquid F NH3 mol/s input rate of ammonia as a solution H Pa m3/mol Henry constant k m3/kgs reaction rate constant in Eq. 3 k La 1/s product of mass transfer coefficient and area K kg/m3 Monod constant in Eq. 1, (for oxygen: mol/m3) K P kg/m3 product inhibition constant in Eq. 1 m kg/(m3s) maintenance coefficient M –Mth loop in the physical mixing model (M=1−6) n– number of ideally mixed cascades in a recirculation loop N–Nth element in a loop with the stirrer compartment (N=1−(n+1)) NH3 mol/m3 concentration of ammonia, in liquid – mol/mol in the gas phase O mol/m3 concentration of oxygen, in liquid – mol/mol in the gas phase p Pa pressure P kg/m3 product concentration r kg/(m3s) reaction rate R Pa m3/(mol K) universal gas constant S kg/m3 substrate concentration t s time V m3 liquid volume of reactor V tot m3 volume of liquid+gas phase in reactor V m m3 liquid volume of ideally mixed stirrer compartment V M,N m3 liquid volume of Mth and Nth cascade element V G,M,N m3 gas volume of the Mth and Nth cascade element Y kg/kg yield coefficient, e.g. Ysx yield coeff. of biomass from substrate Greek symbols μ 1/s specific growth rate μmax 1/s maximum value of the growth rate ɛ– gas hold-up in the reactor Subscripts ax axial direction G gas phase in inlet L liquid M Mth loop N Nth element in a loop including the stirrer compartment as well O oxygen P product rad radial

Notizen: Abstract Pyrolysis mass spectrometry was used to characterise Staphylococcus aureus isolates from an outbreak of post-operative wound infections on a mixed surgical ward. The PyMS results were compared with those of phage typing. Both suggested a single strain of S. aureus, of phage type 3C, 55,71, was responsible for six of the 13 wound infections. PyMS differentiated an isolate from a member of staff of similar phage type to the epidemic strain, which had previously been considered to be the point source for the outbreak. PyMS is a rapid and inexpensive technique for investigating nosocomial outbreaks, including those caused by S. aureus and, in this instance, was more discriminatory than phage typing.