Electron spin resonance investigation of ultra-small double walled carbon nanotubes embedded in zeolite nanochannels.

We report on the low temperature electron spin resonance (ESR) properties of ultra-small (0.45 nm) double walled carbon nanotubes (DWCNTs) embedded in zeolite nanochannels. An isotropic ESR signal is observed at g(c) = 2.002 77 with the spin density (S = 1/2) âˆ¼ 10(19) g(-1), which is suggested to originate from the carbon related point defects in the DWCNTs. Measurements of the ESR line width and signal intensity as a function of temperature indicate that the spins are of a localized nature as opposed to the conduction type electrons observed in large diameter CNTs. The results are consistent with the suggestion that electrons are trapped at interstitial defects. The observed linear frequency dependence of the ESR line width of embedded DWCNTs points to 'strain' as the prime source of broadening. By contrast, the study of free standing DWCNTs shows the presence of a distinctly superlinear frequency dependence of the signal width at low temperatures. The possible origin of the frequency dependence is discussed.

Bioconcentration and biomagnification of mercury and methylmercury in North Sea and Scheldt estuary fish.

Total Hg and MMHg concentrations were assessed in more than 350 fish and shellfish samples. Hg concentrations in Greater North Sea fish of prey range from 0.039 mg kg(-1) wet weight (ww; for ray) to 0.61 mg kg(-1) ww (for dogfish) and for all other fish species, from 0.045 mg kg(-1) ww (for plaice) to 0.33 mg kg(-1) ww (for sand sole), with 95 +/- 2% of the Hg content in the MMHg form. In Belgian coastal zone, fish concentrations range from 0.063 mg kg(-1) ww for plaice to 0.13 mg kg(-1) ww for flounder, with 82-87% of the Hg content in the MMHg form. In fish of the Scheldt, which is a very polluted estuary, Hg levels, as well as the percent MMHg of the total Hg, were lower than in the two zones previously mentioned. The intraspecies variability is of the order of 50% in each of the three zones. In liver tissue, a much larger variability was observed than in muscle tissue, except for fish species of the Scheldt. In most cases, the MMHg fraction in a particular fish species is inversely related to the intraspecies variability. Bioconcentration and biomagnification factors (BCF and BMF, respectively) were assessed. MMHg-BMFs were a few orders of magnitude higher than Hg(inorganic)-BMFs, and for the same species were always highest in the Greater North Sea and lowest in the Scheldt. For each of the Belgian coastal zone four species, a weak positive correlation between Hg content and fish length was found; however, the larger the size-range, the better the correlation. Taking fish length into account, a statistically significant difference in contamination level was observed for species sampled from the different geographical zones.

Total and toxic arsenic levels in north sea fish.

Levels of arsenic contamination in muscle and liver tissue of 25 sea fish and 4 shellfish species from the North Sea were determined. Analyses were done by both ICP-MS and HG-AFS to distinguish between nontoxic and toxic fractions of As. Highest total As concentrations were found in lemon sole, dogfish, ray, and witch. Average total As concentrations in these fish species were higher than 20 mg kg(-1) WW. The same species as well as the other flatfishes contained the highest amounts of toxic As (> 0.1 mg kg(-1) WW). Toxic fractions (AsTox/AsT%) above 2% were found in the following six species: seabass, ling, john dory, pouting, dab, and brill. No preferential concentration in the liver compared to the muscle was observed. In a worst-case scenario (when fish has been dried or smoked and the toxic As level is high; for example 0.5 mg kg(-1) WW), the As content of North Sea marine food may reach harmful levels. A normalization reflecting the toxic potential of sea fish was made. Shark and ray and most flatfish species have positive (high) normalized AsTox values.By ANOVA testing we compared the individual AsT concentrations of samples of the same species (intraspecies variability). Significant differences for some fish species were observed; significantly higher AsT concentrations were found in dogfish from the French coast versus the western North Sea and in common sole from the Bay of the Seine, in the north of France, versus the western North Sea.

Prevalence and causes of anaemia in a geriatric hospitalized population.

Of 732 consecutive patients admitted to an acute geriatric ward, 178 (24%) were found to be anaemic (haemoglobin of 115 g/l or below). An appropriate cause responsible for anaemia was identified in 83%. The anaemia of chronic disorders (ACD) (35%) and iron deficiency anaemia (15%) were the commonest causes. The spectrum of disorders associated with ACD is much broader than the classical category of infectious, inflammatory and malignant disorders. The relatively high prevalence of the myelodysplastic syndrome (5%) is striking and this syndrome as a cause of anaemia in geriatric patients deserves more attention than it has so far received. No obvious cause was found in 17%. The clinical significance of this finding remains unclear.

Spontaneous fracture of the catheter of a totally implantable venous access port: case report of a rare complication.

A case of spontaneous fracture of the outlet catheter of a totally implantable venous access port (IVAP) is presented. Thirty-seven weeks after implantation, the outlet catheter was broken at the entrance into the left subclavian vein. The distal part was embolized in the left pulmonary artery. The embolized remnant was retrieved in an outpatient setting, using a grasping forcipal catheter through a 7 French longsheath. Experimental study of the catheter revealed that it had been broken due to a local cause, probably the long-standing compression at the narrow space between clavicle and first rib. It is emphasized to ascertain the position and intactness of an IVAP before using it to infuse cytostatic agents.