Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for spatially resolved trace analysis of early-medieval archaeological iron finds.

The suitability of laser ablation ICP-MS for minor and trace analysis of archaeological iron finds, produced by a direct reduction process in a 'bloomery' furnace, is reported. The analysis of elemental impurities in the iron can provide useful archaeometallurgical information on the production process and the provenance of the iron. Since, even after refinement, the iron resulting from this process may contain many inclusions (slag, charcoal, holes, etc.), a method should be used with sufficient spatial resolution to preclude the inclusions from the analysis. The ablation parameters are selected such that ablation craters of approx. 100 microm in diameter are obtained. The method is validated with low alloy steel and cast iron standard reference materials and by a comparative analysis with electron probe microanalysis (EPMA). The precision is limited mainly by the homogeneity of the iron, rather than by instrumental reproducibility. The advantages and drawbacks of the method are briefly compared with EPMA. Preliminary results from the analysis of archaeological iron samples from excavations at Develier-Courtetelle (Canton Jura, CH), Neftenbach (Canton Zurich, CH), Wartau (Canton St Gallen, CH) and Mont Chemin (Canton Valais, CH) are given.

Inductively coupled plasma mass spectrometry: a versatile tool for a variety of different tasks.

In a laboratory that is working in many different fields, a systematic approach is needed to decide efficiently how a given analytical task should be handled. Four typical examples are presented to show how ICP-MS may be used to solve client's problems. The examples are: the identification of lead projectiles, the determination of total and leachable fractions of impurities in a polymer (PVDF), used for manufacturing components of ultrapure water distribution systems, the authentication of antique silver alloys, and the determination of rare earth elements in geological materials. These examples demonstrate not only typical challenges for the instruments and the analysts handling them, but also ways to reach a satisfactory solution within a reasonable amount of time.

Functionality of probiotics and intestinal lactobacilli: light in the intestinal tract tunnel.

The commercial interest in functional foods that contain live microorganisms, also termed probiotics, is paralleled by increasing scientific attention to their functionality in the digestive tract. Most studies are focused on intestinal Lactobacillus species, which are part of the natural gastro-intestinal microbiota, and include analysis of colonisation factors and other interactions with the host, the design of novel or improved strains with specific health benefits, and the application of sophisticated molecular tools to determine their fate and activity in situ.

Desiccant recovered, Crohn's disease discovered.

Foreign bodies occasionally lodge in strictures due to Crohn's disease. Most cases involve patients known to have Crohn's disease. However, some patients deny or cannot recall ingestion of foreign bodies. Gastrointestinal obstruction caused by a foreign body is a rare presentation of Crohn's disease. We report the first case of Crohn's disease presenting as gastrointestinal obstruction resulting from accidental ingestion of a pharmaceutical desiccant.

Waxing and waning of slow waves in intestinal musculature.

Electrical slow waves from cat or rabbit small intestine show more variability when recorded in vivo than in vitro. One pattern of variation is waxing and waning of amplitude, or "spindling," during which two rhythms of slightly different frequency come in and out of phase. Fourier power analyses of slow waves during spindles show two frequency peaks of slow waves differing by 0.4-5.0 waves/min and corresponding to measured spindle durations of 12-150 s. Spindles can be induced in vitro in rabbit intestine by K depolarization of approximately 15 mV. Histograms of intracellular recordings of slow nonspindling waves show variation of 0.5-1.0 s on either side of a mean slow wave duration. Spindles are abolished by treatments that reduce electrical coupling between cells, e.g., hypertonic sucrose or lowered pH, but changes in calcium do not alter spindles. Simultaneous recordings by two electrodes in the longitudinal axis show synchrony of spindles at 2- to 3-mm but not at 5-mm separation and synchrony circumferentially to the opposite side of a segment. Contractions, both in vivo and in vitro, correspond with electrical spindles in amplitude. Spindle durations were significantly shorter in vivo than in vitro, indicating a significantly greater difference in vivo in the competing frequencies at the point of recording (P less than 0.01). Three conditions favoring waxing and waning are slight depolarization, variation in slow wave frequency at a point, and electrotonic coupling between muscle fibers. Spindles provide for rhythms of contractions of a 1- to 2-min period.