Role of temperature in de-mixing absorbance spectra composed of compound electrolyte solutions.

This work is focused on the role of temperature in the de-mixing of absorbance spectra measured in mixed aqueous Na2SO4 and NaNO3 solutions. First, the influence of temperature on the absorbance spectrum of demineralized water was determined. Second, the absorbance spectra of five separate electrolytes (NaNO2, NaNO3, CaCl2, K2CO3, and NaOH) at three temperatures (4°C, 25°C, and 50°C) for concentrations ranging from 0.0625 M to 0.5 M were examined. These five electrolytes show similar temperature dependencies. Finally, absorbance spectra of mixed solutions were investigated at temperatures of 5°C, 15°C, 25°C, 35°C, and 45°C for concentrations ranging from 0.0625 M to 0.5 M per electrolyte in the mixture. The spectral window from 650 to 1100 nm was utilized to observe the ionic and temperature influences on the vibrational modes of the OH bond in the solvent molecules. The effects of dissolving Na2SO4 and NaNO3 are nonlinearly cumulative at lower temperatures indicating extended alteration of the water structure beyond the first hydration shell. A similar trend was observed for a mixture of Na2CO3 and NaCl. Furthermore, it was found that higher temperatures are better for recovering the separate component absorption signatures of an electrolyte mixture. The near-infrared spectral regime is well suited for integrated sensing, and therefore these results can help in designing an integrated sensor to identify inorganic species in water.

Prokaryotic transport in electrohydrodynamic structures.

When a high-voltage direct-current is applied to two beakers filled with water, a horizontal electrohydrodynamic (EHD) bridge forms between the two beakers. In this work we study the transport and behavior of bacterial cells added to an EHD bridge set-up. Organisms were added to one or to both beakers, and the transport of the cells through the bridge was monitored using optical and microbiological techniques. It is shown that Escherichia coli top10 (Invitrogen, Carlsbad, CA, USA) and bioluminescent E. coli YMC10 with a plasmid (pJE202) containing Vibrio fischeri genes can survive the exposure to an EHD liquid bridge set-up and the cells are drawn toward the anode due to their negative surface charge. Dielectrophoresis and hydrostatic forces are likely to be the cause for their transport in the opposite direction which was observed as well, but to a much lesser extent. Most E. coli YMC10 bacteria which passed the EHD bridge exhibited increased luminescent activity after 24 h. This can be explained by two likely mechanisms: nutrient limitation in the heavier inoculated vials and a 'survival of the strongest' mechanism.

Morphology of water electrosprays in the simple-jet mode.

Experiments were conducted in order to study and characterize electrohydrodynamic atomization in the simple-jet mode for inviscid liquids. The operational window of this mode regarding the electric potential and liquid flow rate is presented. From the data it could be concluded that this mode can be divided by the characteristics of its breakup mechanism and that these characteristics are a function of the liquid Weber number and the electric Bond number for a given setup. Additionally we were also able to calculate the average charge per droplet and define the average size of primary and satellite droplets. The dispersion of the spray was also studied regarding its relation to the liquid Weber number and to the electric Bond number. We conclude that simple-jet mode electrosprays are a good option for applications which require monodisperse micrometer droplets with high throughput.

Reverse movement and coalescence of water microdroplets in electrohydrodynamic atomization.

When a high voltage is applied to a liquid pumped through a needle, charged microdroplets can be formed, which are carried along the electric field lines. This phenomenon is called electrohydrodynamic atomization (EHDA), or simply electrospray. In this work we show that in the case of water, droplets may reverse their paths flying back toward the liquid meniscus, sometimes making contact with it. Such reverse movement is caused by polarization of the water inside the strong electric field. To understand this phenomenon we developed a way to calculate the droplet charge using its trajectory obtained by high-speed imaging. The values found showed that these droplets are charged between 2.5% and 19% of their Rayleigh limit.

Genetically altered AMPA-type glutamate receptor kinetics in interneurons disrupt long-range synchrony of gamma oscillation.

Gamma oscillations synchronized between distant neuronal populations may be critical for binding together brain regions devoted to common processing tasks. Network modeling predicts that such synchrony depends in part on the fast time course of excitatory postsynaptic potentials (EPSPs) in interneurons, and that even moderate slowing of this time course will disrupt synchrony. We generated mice with slowed interneuron EPSPs by gene targeting, in which the gene encoding the 67-kDa form of glutamic acid decarboxylase (GAD67) was altered to drive expression of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor subunit GluR-B. GluR-B is a determinant of the relatively slow EPSPs in excitatory neurons and is normally expressed at low levels in gamma-aminobutyric acid (GABA)ergic interneurons, but at high levels in the GAD-GluR-B mice. In both wild-type and GAD-GluR-B mice, tetanic stimuli evoked gamma oscillations that were indistinguishable in local field potential recordings. Remarkably, however, oscillation synchrony between spatially separated sites was severely disrupted in the mutant, in association with changes in interneuron firing patterns. The congruence between mouse and model suggests that the rapid time course of AMPA receptor-mediated EPSPs in interneurons might serve to allow gamma oscillations to synchronize over distance.

Effects of silibinin and of a synthetic analogue on isolated rat hepatic stellate cells and myofibroblasts.

Hepatic stellate cells and the derived myofibroblasts play a central pathogenic role in liver fibrogenesis. In order to identify the still unknown hepatoprotective properties of the flavonoid silibinin and the related pyridylchromone NH40 x HCl (2-(3-pyridyl)-4-H-1-benzopyran-4-one hydrochloride), their effects on isolated rat hepatic stellate cells and derived myofibroblasts were determined. Concentrations of 10(-4) mol/l silibinin reduced the proliferation of freshly isolated rat hepatic stellate cells by about 75%, but had no detectable effect on their viability, morphology and their cytoskeletal architecture. It reduced the transformation towards myofibroblasts and down-regulated the gene expression of extracellular matrix components and the profibrogenic transforming growth beta. Whereas silibinin concentrations higher than 10(-4) mol/l were toxic, lower concentrations had no effects on the proliferation and transformation behavior. Although 10(-4) mol/l NH40 x HCl reduced the proliferation rate by about 50%, this substance had no significant effect on the transformation process. The results indicate that one important aspect of the potential antifibrotic properties of silibinin might be the inhibition of hepatic stellate cell proliferation and transformation.

Chronic and acute transtentorial herniation with tumours of the posterior cranial fossa.

In patients with expanding lesions of the posterior fossa general hyper-reflexia (and bilateral latency shifts of auditory evoked brain stem potentials) have been noted as possible symptoms of chronic ascending transtentorial herniation. After ventricular tap, this chronic herniation may evolve into acute herniation with progressive reduction of consciousness which in our experience can only be survived by decompression of the compressed brain stem. The chronic transtentorial herniation is related morphologically to demyelination of the pyramidal tracts and the auditory pathways, whereas the acute transtentorial herniation is related to microcirculatory disturbances in the reticular formation of the mesencephalo-pontine junction.

Demonstration of early capillary lesions in the brain by means of artificial reperfusion.

Nine patients are reported in whom functional brain death was determined as exactly as possible by neurological (in part also electroencephalographic and/or angiographic) examination in combination with analysis of the clinical history. During the first hour, at 2-4 hr, and later than 4 hr after the occurrence of functional brain death, the mean systemic pressure was raised to 30% above normal by infusion of Arterenol. The infusions lasted 15-30 min; in spite of the raised blood pressure, the patients died of cardiovascular attention to vascular damage; none was found whenever the reperfusion was completed within the first hour after determination of circulatory arrest. In all three cases in which reperfusion was performed, after more than 4 hr the neuropathological findings were similar. In one case the EEG showed a burst-type pattern during reperfusion within the first hour after determination of brain death.

[Spontaneous intracerebellar haematoma in childhood (author's transl)]. / Spontane intrazerebelläre Hämatome im Kindesalter

Spontaneous cerebellar haemorrhage accounts for 10% of all intracranial spontaneous haematomas. It is a disease which principally affects patients over middle age, and it is rare in childhood. To twelve cases previously reported we now add a further three. Attention is drawn to the diagnostic difficulties and the values of echoencephalography, angiography, and computerized axial tomography in diagnosis and localisation of the condition. Prognosis can be good even in cases in poor condition of diagnosis and treatment are prompt.

[Intracranial volume fluctuations. The importance of exact CSF-measurements in CSF-drainages (author's transl)]. / Intrakranielle Volumenschwankungen. Die Bedeutung exakter Volumenmessungen bei Liquordrainagen.

The significance of simultaneous I.C.P. measurements together with exact C.S.F. volume measurements through the same ventricular catheter is emphasized. A new method using an electronic device is introduced. Volume fluctuations are shown as correlations of plateau waves. The fluctuating amount of C.S.F. (the probable equivalent of a plateau wave) ranges between 16 and 32 ml. Only with disturbed autoregulation is there a close correlation between the S.A.P. and the I.C.V. (intracranial volume) change. Simultaneous I.C.P. measurements up to a maximum pressure, determined by the level of the drainage system and corresponding to the primary brain dysfunction, together with electronic measurement of the drained C.S.F., seem to be ideal for the patient and for scientific purposes.

Acute spontaneous volume fluctuation in the brain. A contribution to the interpretation of plateau waves. Results of CSF measurements with ventricular drainage.

Primarily the theoretical background of the relation between the intracranial pressure and the volume is discussed. From the definite relationship between volume and pressure it is deduced that with the appropriate equipment intracranial volume changes may be measured instead of the I.C.P. The exact measurement of the volume of CSF drained in relation to the drainage time enable us to differentiate disturbances of the C.S.F. circulation in patients. Furthermore we were able to correlate "plateau waves" with certain amounts of volume fluctuations; these were shown in amounts of drained C.S.F. between 16 and 32 ml. Some scientific aspects of this new method and possible results are pointed out.

[Clinical significance of encycling clips in neurosurgery]. / Uber die klinische Bedeutung von Manschettenclips in der Neurochirurgie

It is reported how, in 5 cases of arterial haemorrhage, the ligature of an artery was avoided by the use of Heifetz encircling clips with teflon liner. Two of the five patients had aneurysms. The remaining 3 were suffering from brain tumours. Postoperative computer tomography together with neurological follow up examinations indicated, that in two cases there was no disturbance of cerebral circulation. With a carotid angiography it was possible to show that in the other three cases normal flow through the arteries was maintained, 2, 11 and 45 days after emplacement of the clip.

[Prognosis and long-term prognosis of epidural haematoma (a study of 83 patients) (author's transl)]. / Prognose und Spätprognose des epiduralen Hämatoms Eine Studie über 83 Patienten

1. Early detection and treatment of epidural haematoma is vital to the chance of survival. In this respect physician's training needs to be improved. 2. The operation method of choice, particularly in the case of advanced midbrain lesions, is the extensive decompression operation (hemicranectomy) with duraplasty. In each case it is imperative to pay special attention to the relationship between blood pressure and brain perfusion until the state of decompressive is reached. 3. Late complications such as a disturbed circulation of the cerebrospinal fluid may occur and should be prevented by a shunt-operation. 4. ECG changes are still detectable even after many years. However, they give little indication on the patient's tendencies to fits. Post-traumatic cases of epilepsy may even occur more than five years after injury. 5. Patients suffering from epidural haematoma are in need of careful medical, psychiatric and social care for many years after injury, even if they seem to have been restored both neurologically and psychiatrically at the time of hospital discharge.