Two-dimensional heterogeneous dynamics at the surface of a colloidal suspension.

We report on an x-ray photon correlation spectroscopy experiment investigating the surface structure and dynamics of colloidal particles suspended in a supercooled viscous liquid. The static structure factor in the direction parallel and perpendicular to the surface reveals a more disordered structure at the surface as compared to the bulk. The particles display heterogeneous ballistic dynamics parallel to the surface. The particle dynamics in the direction perpendicular to the surface is much slower and does not show the hallmarks of ballistic motion.

Measuring temporal speckle correlations at ultrafast x-ray sources.

We present a new method to extract the intermediate scattering function from series of coherent diffraction patterns taken with 2D detectors. Our approach is based on analyzing speckle patterns in terms of photon statistics. We show that the information obtained is equivalent to the conventional technique of calculating the intensity autocorrelation function. Our approach represents a route for correlation spectroscopy on ultrafast timescales at X-ray free-electron laser sources.

Dynamics in dense suspensions of charge-stabilized colloidal particles.

The dynamic behavior of charge-stabilized colloidal particles in suspension was studied by photon correlation spectroscopy with coherent X-rays (XPCS). The short-time diffusion coefficient, D(Q) , was measured for volume concentrations phi < or = 0.18 and compared to the free particle diffusion constant D(0) and the static structure factor S(Q) . The data show that indirect, hydrodynamic interactions are relevant for the system and hydrodynamic functions were derived. The results are in striking contrast to the predictions of the PA (pairwise-additive approximation) model, but show features typical for a hard-sphere system. The observed mobility is however considerably smaller than the one of a respective hard-sphere system. The hydrodynamic functions can be modelled quantitatively if one allows for an increased effective viscosity relative to the hard-sphere case.

On the physiological function of lithium from a psychiatric view point.

Lithium is a naturally occurring alkali metal, which living organisms ingest from dietary sources and which is also present in trace amounts in the human body. In much higher concentrations, lithium is effective as a medication for mania and mood swings including manic depressive disorders. Many studies have shown that a deficiency in 'endogenous' lithium, i.e. lithium in food and drinking water, can lead to defects in growth and development in animals and to grave psychopathological problems in humans. It is therefore conceivable that lithium has an essential function in the physiological regulation of mood and that a subgroup of pathological mood disorders cause a bodily requirement for drastically higher concentrations of lithium in compartments. Taking lithium long-term could have a prophylactic effect on this kind of change in bodily requirements.

[Lead poisoning caused by a Greek ceramic cup]. / Bleivergiftung durch griechische Keramiktasse.

HISTORY AND ADMISSION FINDINGS: A 24-year-old woman, an administrative employee, was admitted with colicky abdominal pain and constipation, as well as breathing-related chest pain of recent onset with cough and sometimes blood-streaked sputum. She had previously been unsuccessfully treated for gastritis and adnexitis. On physical examination revealed diffuse, ill-defined abdominal pain on pressure and mild tachycardia, but was otherwise unremarkable. INVESTIGATIONS: Electrocardiogram, chest radiogram, lung scintigraphy, abdominal sonography, oesophago-gastro-duodenoscopy and gynaecological examination indicated nothing abnormal. Laboratory tests showed microcytic anemia, slight leucocytosis and anisocytosis, as well as polychromasia and basophilic stippling of erythrocytes. The 24-h urinary porphyrin concentration was elevated. DIAGNOSIS TREATMENT AND COURSE: Precise differentiation of porphyrins in urine, stool and erythrocytes by enzymatic measurement first raised the suspicion of lead poisoning. Whole-blood lead concentration was markedly raised to 600 micrograms/l (normal up to 90 micrograms/l) and 170 micrograms/dl in urine (normal up to 80 micrograms/dl). A ceramic cup from Greece was traced as the source of the lead, the patients having regularly for over 2 1/2 months drunk lemon instant-tea from it. She was treated with oral doses of DMPS (sodium salt of 2,3-dimercapto-1-propanesulphonic acid), 5-10 mg/kg 3x daily for 2 days, followed by 2.5 mg/kg 2 x daily, until lead concentrations in blood and urine had become normal, when all symptoms disappeared: detoxification was complete within 4 months. CONCLUSION: This case impressively illustrates how difficult it can be to diagnose lead poisoning and identify its source. Oral DMPS is a practicable and efficacious form of treatment.