Dye-loaded zeolite L sandwiches as artificial antenna systems for light transport

The synthesis and characterization of dye loaded zeolite L sandwiches acting as artificial antenna systems for light harvesting and transport is reported. A set of experimental tools for the preparation of neutral dye-zeolite L materials ranging from low to maximum packing densities has been developed. The role of co-adsorbed water and the distribution of molecules between the inner and the outer surface were found to be the determining parameters. p-Terphenyl (pTP) turned out to be very suitable for studying these and other relevant parameters of neutral dye-zeolite L materials. We observed that pTP located in the channels of zeolite L can reversibly be displaced by water. This can be used when synthesizing such materials. We also observed that all-trans-1,6-diphenyl-1,3,5-hexatriene (DPH) which is very photolabile in solution is stable after insertion into zeolite L. By combining our extensive knowledge of these systems with ion-exchange procedures developed in an earlier study, we have realized the first bi-directional three-dye antenna. In this material the near UV absorbing compounds DPH or 1,2-bis-(5-methyl-benzoxazol-2-yl)-ethene (MBOXE) are located in the middle part of zeolite L nanocrystals followed on both sides by pyronine (Py) and then by oxonine (Ox) as acceptors. Fluorescence of the oxonine located at both ends of the cylindrical zeolite L crystals was observed upon excitation of the near UV absorber in the middle section at 353 nm, where neither oxonine nor pyronine absorb a significant amount of the excitation light.

Intrazeolite diffusion kinetics of dye molecules in the nanochannels of zeolite L, monitored by energy transfer.

Intracrystalline diffusion kinetics of two cationic dyes in an aqueous medium were studied by means of energy transfer from an electronically excited donor to an acceptor located in one-dimensional crystalline channels. Different stages of the diffusion processes were visualized by using fluorescence microscopy. The picture illustrates the counter diffusion of the dye (hatched block) and water molecules (circles) in such a one-dimensional channel; the diffusion of the water molecules past the dye (1 → 2) is the rate-determining step rather than the period between encountering different dyes (2 → 3).

Tartrate-resistant acid phosphatase (TRAP) activity in serum: potential use in assessing bone resorption in patients with multiple myeloma.

We measured serum tartrate-resistant acid phosphatase (TRAP) activity in 120 healthy subjects and 35 patients with multiple myeloma as well as urinary hydroxyproline excretion in the myeloma patients. Young subjects (0-18 years) showed higher TRAP levels (ANOVA p less than 0.01) compared with the other age classes due to the more active bone remodelling processes associated with growth. Myeloma patients with bone lytic lesions (MM+) showed higher serum TRAP values than controls (p less than 0.01). Hydroxyproline excretion was higher in MM+ patients but the difference between patients with and without bone lesions was not statistically significant. Our data suggest that serum TRAP activity may be a suitable, simple biochemical test to assess bone turnover in patients with multiple myeloma but that its clinical usefulness as a marker of bone resorption needs further evaluation.

Sialic acid, ferritin and CEA levels in peripheral blood and blood draining from the tumor in breast cancer.

Concentrations of total serum N-acetyl-neuraminic acid, carcinoembryonic antigen, ferritin, lactate dehydrogenase, creatine phosphokinase and total proteins were measured in both tumor drainage blood (axillary vein) and in peripheral blood taken during surgery from 44 breast cancer patients. There were no significant differences in any of the markers between mean values in peripheral and tumor drainage blood, between cancer patients and healthy controls, between patients with or without axillary lymph node metastases, or according to the site of breast mass.

The speciation of the chemical forms of arsenic in the biological monitoring of exposure to inorganic arsenic.

Total As content may be determined in blood and urine by means of an AAS method that involves reduction of As to its volatile hydride and ashing at 600 degrees C with MgO and Mg (NO3)2. Separation of inorganic As (InAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMAA) by ion-exchange chromatography, followed by direct AAS analysis, allows the determination of each As species in the urine. In a reference population of 148 subjects with only normal environmental exposure to As, total As concentration in the urine averages 17.2 +/- 11.1 micrograms/l. Urinary As consists of 10% each of InAs, MMAA and DMAA, the remaining 70% consisting of other forms of organic As. Blood As concentration averages 5.1 +/- 6.9 micrograms/l and correlates significantly with the urinary concentration of InAs and the sum of its metabolites (InAs + MMAA + DMAA). Inorganic arsenic undergoes methylation in the organism. After ingestion of high quantities of As2O3, the time course of excretion of its metabolites indicates that As methylation occurs by a saturable mechanism. In workers exposed to As2O3, InAs, MMAA and DMAA are the only chemical forms of As excreted in the urine that are relevant to a study of occupational exposure. Blood As concentration is proportional to exposure and correlates only with urinary DMAA excretion; DMAA seems to be the most appropriate single indicator of exposure. At high levels of exposure (total As excretion above 200 micrograms/l), As accumulates in the organism and DMAA excretion reflects its accumulation. At low levels of exposure (total As excretion below 50 micrograms/l) a short-term accumulation does not occur and the best biological indicator of exposure is InAs excretion. Seafood ingestion brings about a marked increase in urinary excretion of total As that lasts for 24-48 h and is not accompanied by any increase in InAs, MMAA or DMAA excretion. Organic As from seafood does not mix with the pool of inorganic As in the organism and may be separately detected in urine. In the biological monitoring of human exposure to As, particularly in the case of high urinary values, the speciation of the chemical forms of As in urine is necessary in order to establish with certainty the source, industrial or alimentary, of exposure.

Cadmium concentrations in blood and urine of pregnant women at delivery and their offspring.

The levels of cadmium in blood (CdB) and in urine (CdU) were measured in 40 women at delivery and in their offspring. The women were not occupationally exposed to cadmium. The CdB levels in the pregnant women were significantly lower than in a control group consisting of 40 subjects of the same sex and age living in the same area. The difference can probably be ascribed to the physiological hemodilution that takes place in pregnancy. The CdU levels in the two groups were identical, which suggests that no mobilization of the metal from tissue deposits occurs during pregnancy. The presence of cadmium in the blood and urine of the newborn demonstrates that cadmium crosses the placental barrier. There was a rather high correlation between the CdU levels of mothers and offspring. Since only traces of cadmium are present in tissues at birth, it is speculated that the CdU levels in the newborn are influenced by the tissue deposits of cadmium in the mother. Further research is required to ascertain whether, in the case of women occupationally exposed to cadmium or living in cadmium polluted areas, transfer of the metal across the placenta can produce toxic effects in the foetus.

Significance of arsenic metabolic forms in urine. Part I: Chemical speciation.

The aim of this research has been to develop analytical procedures whereby the various chemical forms of arsenic present in urine can be distinguished and further data on the biotransformation of absorbed arsenic can be acquired. The separation of inorganic arsenic ( InAs ), monomethylarsonic acid ( MMAA ), and dimethylarsinic acid ( DMAA ) in urine was performed by ion-exchange chromatography on AG 50 W-X8 resin. Arsenic was then measured directly on the eluted fractions by atomic absorption spectrophotometry, after the reduction of arsenic to the correspondent arsine. In 160 subjects with no occupational exposure to arsenic compounds, InAs , MMAA , DMAA each accounted for about 10% of the total arsenic urinary excretion (17.2 +/- 11.1 micrograms/1), thus indicating that in the normal population over 60% of arsenic in urine is present in other organic forms. After eating marine food, there was a marked increase of urinary output of arsenic, but no increase was observed in InAs , MMAA and DMAA urinary excretion. In the biological monitoring of exposure to inorganic arsenic, particularly in the case of high urinary excretion values, the differentiation of the excreted forms of arsenic is necessary to establish with certainty the source (industrial or alimentary) of arsenic.

Behaviour of plasma and urinary aluminium levels in occupationally exposed subjects.

Aluminium in urine (AlU) and in plasma (AlP) was determined in seven subjects occupationally exposed to environmental concentrations of aluminium below or equal to the TWA (5 mg/m3). The AlU levels in these workers were markedly higher than those found in the control group. The levels of the indicator were definitely higher at the end of the shift than at the beginning of the same working day; also, the AlU levels were higher on Friday morning than on Monday morning. After an interruption in work of two weeks, the values of the indicator underwent a marked reduction and were then only slightly higher than those of the control group. Occupational exposure to fumes produced higher AlU levels than exposure to dusts, and in the subjects exposed to fumes the AlU levels were clearly influenced by the degree of exposure. The levels of aluminium in plasma in the exposed workers on the other hand, hardly differed from the levels found in the control group. These data appear to indicate that, whereas AlU allows daily and weekly exposure to be evaluated, AlP cannot be used as an indicator of occupational exposure, at least in the case of brief exposures to environmental concentrations below or equal to the TWA.