Prediction of Electrolyte Distribution in Technical Gas Diffusion Electrodes: From Imaging to SPH Simulations

The performance of the gas diffusion electrode (GDE) is crucial for technical processes like chlorine–alkali electrolysis. The function of the GDE is to provide an intimate contact between gaseous reactants, the solid catalyst, and the liquid electrolyte. To accomplish this, the GDE is composed of wetting and non-wetting materials to avoid electrolyte breakthrough. Knowledge of the spatial distribution of the electrolyte in the porous structure is a prerequisite for further improvement of GDE. Therefore, the ability of the electrolyte to imbibe into the porous electrode is studied by direct numeric simulations in a reconstructed porous electrode. The information on the geometry, including the information on silver and PTFE distribution of the technical GDE, is extracted from FIB/SEM imaging including a segmentation into the different phases. Modeling of wetting phenomena inside the GDE is challenging, since surface tension and wetting of the electrolyte on silver and PTFE surfaces must be included in a physically consistent manner. Recently, wetting was modeled from first principles on the continuum scale by introducing a contact line force. Here, the newly developed contact line force model is employed to simulate two-phase flow in the solid microstructures using the smoothed particle hydrodynamics (SPH) method. In this contribution, we present the complete workflow from imaging of the GDE to dynamic SPH simulations of the electrolyte intrusion process. The simulations are used to investigate the influence of addition of non-wetting PTFE as well as the application of external pressure differences between the electrolyte and the gas phase on the intrusion process.

Melanocytes in nevi and melanomas synthesize basement membrane and basement membrane-like material. An immunohistochemical and electron microscopic study including immunoelectron microscopy

Light microscopic studies have shown that nevus cell nests and melanoma nests are surrounded by basement membrane (BM) material containing type IV collagen and laminin. This study confirms this by electron microscopy and relates it to proteins which interact with the basement membrane. Nevi except for dysplastic and Spitz nevi, malignant melanomas, and melanoma metastases were studied by immunohistopathology, routine electron microscopy (EM), and immunoelectron microscopy. The lesions were incubated with monoclonal antibody (moAb) against type IV collagen, laminin, and the integrin alpha6 and studied by light microscopy. In addition, melanomas were studied by immuno-EM after incubation with a moAb against matrix metalloproteinase-2 (MMP-2). Nevus cell nests and melanoma nests are surrounded by BM material containing type IV collagen and laminin by immuno-EM. The BM material various in thickness and is amorphous. Type IV collagen, laminin, and MMP-2 are synthesized by melanoma cells as well as adjacent fibroblasts. Destruction or loss of the BM is not mandatory for melanoma invasion or even metastasis. Possibly the BM material is a protective wall for melanoma cells. Interactions between melanocytes and the extracellular matrix of which the BM is a part, can be traced back to the migration of melanocytes from the neural crest.

Aerobic fitness and sympatho-adrenal response to short-term psycho-emotional stress under field conditions

A possible relationship between aerobic fitness (AF), measured by maximal cycle ergometry (CE) and sympatho-adrenal response to acute, short lasting psycho-emotional stress was investigated by monitoring heart rate (fc) and excretion of catecholamines. The activation of the sympatho-adrenal system was characterised by the noradrenaline: adrenaline ratio. A group of 11 healthy men [22.8 (SD 2.52) years] lived under identical environmental conditions; their mean maximal oxygen uptake (VO2max) was 47.1 (SD 3.9) ml.min-1.kg-1. After the physiological and psychological laboratory tests had been completed the fc of the subjects was monitored continuously during the "guerilla slide" and "parachute jump by night", two emotionally stressful military tasks. Maximal fc (fc, max) attained during these events was 84.5% and 83% of fc, max during CE (fc, max, CE), respectively. A significant relationship (r = -0.92, P < 0.0002) between fc, max reached during the stressful tasks and VO2max was found only for the guerilla slide, which was preceded by physical strain, sleep deprivation and energy deficit. One subject with some prior experience in parachuting showed the lowest fc response and the lowest sympatho-adrenal activation in both events, independent of the degree of AF. In conclusion, AF was found to influence the sympatho-adrenal and fc response to acute, short-lasting emotional stress when the stressful event was aggravated by preceding physical strain, the magnitude of the stress response depending largely on individual experience and effective mechanisms for coping with specific stimuli.

The topography of the lymph heart in the domestic chicken (Gallus domesticus)

Although at the time of hatching, the lymph heart of the domestic chicken (Gallus domesticus) is usually considered to have atrophied, our findings suggest otherwise. Apart from the lymphatic-venous (L-V) anastomoses between the thoracoabdominal lymph trunks and the superior vena cava in the chest, there are two other L-V anastomoses in the sacral region. These L-V communications connect the lymph heart with three inter-segmental veins and with the L-V sinus of the dura mater. The topography of the lymph heart was demonstrated using direct and indirect blue dye injections depending on the age of the chicken. Lymphatic continuity was noted up to the 15th week of age from lymphatics of the hindlimb into the lymph heart via the thoracoabdominal lymph trunk, including communications of the lymph heart with the venous system and dural sinus. At 16 weeks of age, lymph flow apparently ceases caudally, but continues superiorly into the venous system. In the egg, the lymph heart may help propel interstitial fluid in the motionless fetus. After hatching, the lymph heart may facilitate fluid propulsion through L-V communications in the spinal canal.

[What does psychotherapy accomplish in the treatment of psychosomatic disorders?]

Psychosomatic disorders are epidemiologically so frequent as often accompanied by psychic (anxiety), vegetative, and psychiatric (depression) symptoms. Efficient psychotherapy of psychosomatic disorders must therefore influence vegetative (peripheric) and central arousal as well as deficient coping strategies. The latter trigger pathologic psychosomatic reaction patterns in (mostly) specific distressfull situations. Psychotherapy of psychosomatic disorders effects: Relaxation of the overactivated and stimulation of the desactivated, a shift of the patient's exclusively somatic attribution of the disease to a psychosomatic one, more efficient coping strategies, a break-up of the pattern "conflict - emotion - vegetative irritation - physiologic reaction".

Spontaneous hematologic recovery from bone marrow aplasia after accidental tenfold overdosage with radiophosphorus

Two patients with polycythemia vera received intravenously an accidental tenfold overdosage of radiophosphorus therapy (60 and 50 mCi 32P, respectively). In both patients, the occurrence of hemorrhagic complications 3 wk after the 32P medication led to detection of the error and referral to our hospital. Upon admission they showed an agranulocytosis, severe thrombocytopenia, and bone marrow aplasia. In both cases, spontaneous recovery of the hematopoiesis was observed from day 40 posttreatment onward. In one patient, a slow but ultimately complete normalization of blood counts and marrow morphology took place, whereas in the other, a mild thrombocytopenia persists. Nearly 5 yr after the accidental overdosage, both patients are clinically well. Symptoms of polycythemia vera have not reappeared up to now. Attempts were made to evaluate the radiation dose absorbed by the bone marrow. In the first patient, the daily 32P excretion was determined from day 22 to day 60, whereas in the other patient a whole body count was performed on day 78 after administration. From these results, an approximate cumulative bone marrow dose of 10 Sv (1000 rem) could be calculated.

Cluster of hepatitis B transmitted by a physician

Over a 4 1/2 year period (1973-77) 41 individuals in a village in eastern Switzerland (population 3000) were admitted to hospital because of acute hepatitis B. This hepatitis incidence was much higher than that in surrounding villages and that in the whole country. An epidemiological survey showed that one of the two general practitioners in the affected village was the source of infection. He had a chronic aggressive hepatitis associated with circulating hepatitis B surface and e antigen. No new cases of hepatitis B occurred in the village in the 3 years after his death.