Chemical and physical properties of cyclone fly ash from the grate-fired boiler incinerating forest residues at a small municipal district heating plant (6MW).

In Finland, the new limit values for maximal allowable heavy metal concentrations for materials used as an earth construction agent came into force in July 2006. These limit values are applied if ash is utilized, e.g. in roads, cycling paths, pavements, car parks, sport fields, etc. In this study we have determined the most important chemical and physical properties of the cyclone fly ash originating from the grate-fired boiler incinerating forest residues (i.e. wood chips, sawdust and bark) at a small municipal district heating plant (6 MW), Northern Finland. This study clearly shows that elements are enriched in cyclone fly ash, since the total element concentrations in the cyclone fly ash were within 0.2-10 times higher than those in the bottom ash. The total concentrations of Cd (25 mg kg(-1); d.w.), Zn (3630 mg kg(-1); d.w.), Ba (4260 mg kg(-1); d.w.) and Hg (1.7 mg kg(-1); d.w.) exceeded the limit values, and therefore the cyclone fly ash cannot be used as an earth construction agent. According to the leached amounts of Cr (38 mg kg(-1); d.w.), Zn (51 mg kg(-1); d.w.) and sulphate (50,000 mg kg(-1); d.w.), the cyclone fly ash is classified as a hazardous waste, and it has to be deposited in a hazardous waste landfill.

Biodegradation of inorganic drug delivery systems in subcutaneous conditions.

Despite extensive efforts to develop delivery systems for oral administration, subcutaneous (s.c.) injection remains the most common way to administer peptide drugs. To limit the number of frequent injections, sustained release systems that are easy to produce, suitable for various drugs, safe and biodegradable are urgently needed. Porous silicon (PSi) has been recognized to be one of the most promising materials for s.c. peptide delivery, but its biodegradation in s.c. tissue has not been studied in vivo, despite extensive in vitro research. In the present study, differently modified PSi microparticles were injected s.c. in mice, after which the morphology of the particles was thoroughly studied with transmission electron microscopy, micro-computed tomography and X-ray diffraction. Furthermore, histopathology of the s.c. tissue was analyzed to evaluate biocompatibility. To the best of our knowledge, this is the first systematic study which reveals the degradation behavior of various PSi materials in vivo. The PSi surface chemistry significantly affected the biodegradation rate of the s.c. injected microparticles. The most hydrophobic PSi microparticles with hydrocarbonized surface showed the lowest biodegradation rate while the hydrophilic microparticles, with oxide surface, degraded the fastest. The results from different empirical methods complemented each other to deduce the biodegradation mechanism of the inorganic delivery system, providing useful information for future development of s.c. carriers.

High-activity carbonic anhydrase isoenzyme (CA II) in human gallbladder epithelium.

Acidification of bile is one of the factors that prevents calcium precipitation and thereby gallstone formation. Carbonic anhydrase II (CA II) has previously been shown to be one of the key factors in the human alimentary tract that regulates the acid-base balance. We demonstrated CA II expression in the human gallbladder epithelium using immunohistochemical techniques, elucidated the CA II content of the epithelium by digital image analysis of the immunohistochemically stained enzyme in samples from 16 patients undergoing cholecystectomy, and correlated the results with the calcium content of the gallstones. Nine patients had symptomatic gallstone disease and seven an acalculous, histologically normal gallbladder. The patients were classified into two groups on the basis of the calcium content of their gallstones: no gallstones or gallstones containing no calcium (Group 1) and gallstones with 2-87% calcium by weight (Group 2). The immunohistochemical techniques showed distinct epithelial CA II-positive staining in most of the gallbladder samples, but digital image analysis revealed distinct variations in staining intensity among them. The median staining intensity index was significantly higher in Group 1 (0.4463) than in Group 2 (0.2376; p = 0.0262). The results suggest that CA II is abundantly expressed in the normal gallbladder epithelium and that decreased expression may be associated with the formation of calcified gallstones. These findings are relevant to the pathogenesis of gallstone disease.

Spectrochemical and thermal analysis of Al-tetrabromophthalate and tetrabromophthalic anhydride. A comparison of methods for determination of aluminium.

A sequential inductively coupled plasma atomic emission spectrometer (ICP-AES) was used to determine Al content in Al-tetrabromophthalate (Al-TBP). Four emission lines of Al (I) at 309.271, 396.152, 308.215 and 394.401 nm were compared. The microwave mineralisation was carried out by using a two-step digestion procedure and HNO(3)-H(2)SO(4). The thermal analysis of Al-TBP and tetrabromophthalic anhydride (TBPA) was performed in the air atmosphere. Statistical tests applied (t-test, F-test) showed no significant differences between the Al results obtained by ICP-AES and thermal method of analysis.

Assessing the critical level of SO2 for Scots pine in situ.

A field survey was performed in eastern Finland, where measured ambient SO2 concentrations were 1.4-3.8 microg m(-3) a(-1) and bulk S deposition 0.17-0.32 g m(-2) a(-1) in 1991-1993. The accumulation of sulphur (S) in needles of Scots pine (Pinus sylvestris L.) was studied with XRF, IC and FESEM analyses and the needle damage examined under a light microscope and by SEM. Foliar N concentrations were also measured. Foliar total S concentrations were observed to be above the normal S level (500-700 microg g(-1)) over almost the whole area. Slight chlorosis and/or necrosis of the needle tips and stomatal areas, changes in the needle surface waxes and localization of S into needle tips and mesophyll cells around the stomata suggested the impact of S deposition, as did the calculations of St/Nt, and 'predicted' and 'excess' S. A concentration of about 900 microg g(-1) may be considered a critical level for foliar St in areas with low N supply.

Preliminary study of the use of terrestrial moss (Pleurozium schreberi) for biomonitoring traffic-related Pt and Rh deposition.

The use of Pt and Rh as active components in automobile catalytic converters has led to increasing concentrations of these elements in several natural matrices. Because of this, the suitability of the use of a terrestrial moss (Pleurozium schreberi) for the passive biomonitoring of traffic-related Pt and Rh deposition was studied. The moss samples collected from Finland in and around areas with heavy traffic had increased Pt and Rh concentrations, with maximum values of 12.2 and 4.5 ng g(-1), respectively. In addition, the concentrations of commonly used catalytic converter additives (Al, Ce, La, Y, and Zr) and some elements related to traffic or mineral dust (Cd, Cu, Fe, Hf, Pb, and Zn) were also measured to obtain more information about the sources of Pt and Rh. Multivariate principal component analysis and cluster analysis were applied for identification of the emission sources of the elements. The results indicated a common traffic-related source of Pt and Rh. However, the results also showed that Pt and Rh concentrations in mosses are increased only in areas located close to traffic lanes.

Heavy metals (Cr, Zn, Ni, V, Pb, Cd) in lingonberries (Vaccinium vitis-idaea L.) and assessment of human exposure in two industrial areas in the Kemi-Tornio region, Northern Finland.

The concentration of Cr, Zn, Ni, V, Pb, and Cd were measured in lingonberries (Vaccinium vitis-idaea L.) sampled at 23 sampling sites around a ferrochrome and stainless steel works and opencast chromium mine in the Kemi-Tornio region, Northern Finland. Two different microwave-assisted digestion procedures were used for sample digestion, i.e., a mixture of HNO3 + H2O2 and a mixture of HNO3 + H2O2 + HCl + HF + H3BO3. According to the results, the digestion procedure with the mixture of HNO3 + H2O2 underestimated especially the Cr concentrations in plant material. The maximum concentrations of Cr (1.3 mg kg(-1), wet weight), Ni (358 microg kg(-1); ww), V (36 microg kg(-1); ww), and Cd (2.4 microg kg(-1); ww) in the immediate vicinity of the point sources were 33, 6, 4, and 8 times higher than the background levels, respectively. The dietary intakes of Cd and Pb were assessed and compared to the health criteria recommendations set by the joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives (JECFA). The results showed that, depending on the consumption of lingonberries, human exposure based on the mean concentrations for Pb and Cd varied between 0.04% and 0.07% for Pb and between 0.04% and 0.09% for Cd compared to the tolerable total quantities of 25 microg kg(-1) for Pb and 7 microg kg(-1) for Cd per body weight per week set by JECFA.

Microwave heated vapor-phase digestion method for biological sample materials.

A microwave heated, vapor-phase nitric acid-hydrogen peroxide digestion method for pulverized, biological sample materials was developed. Sample masses up to 200 mg were digested using calibrated quartz inserts inside first generation type, low-pressure, Teflon-PFA microwave vessels. In the first step, samples were digested in the vapor-phase for 80 min using a progressive heating pattern. Three mL of 70% nitric acid and 0.5 mL of 30% hydrogen peroxide were used as digestion reagents. In the second step, the small residue left after first step digestion was dissolved in 1.4% nitric acid or additionally with 0.5% hydrofluoric acid by heating for 15 min. The digestion method was optimized using pike (Esox lucius) muscle as a test material. The method was further optimized using three certified reference materials. Ca, Cu, Fe, Mg and Zn were determined from NIST-SRM 1577a bovine liver by ICP-AES. Cr and Ni were determined from NIST-SRM 8433 corn bran and NRCC DOLT-2 dogfish liver by GFAAS. For all elements the values obtained were close or within certified limits. Spike recoveries were between 96 to 107%. Digestion efficiency ranged from 91 to 99%.

Development of a modified medium pressure microwave vapor-phase digestion method for difficult to digest organic samples.

A previously developed microwave heated vapor-phase digestion method for biological samples was modified to enable digestion of difficult to digest organic samples. Organic samples containing ca. 100 mg of organic carbon were digested using volume calibrated quartz inserts inside second generation type medium pressure microwave vessels. As digestion reagents, 98% sulfuric acid, 70% nitric acid and 30% hydrogen peroxide were used. The accuracy of the method was tested with six certified reference materials. Elements Ca, Fe, K, Na, Mg, P and Zn were determined from NIST-SRM 8433 corn bran. Elements Al, Fe, Cd, Cu, and Zn were determined from NRCC DOLT-2 dogfish liver. The element Cd was determined from IRMM-VDA Cd in polyethylene No. 001-004 reference materials. These elements were determined from digested samples by ICP-OES. The results were close or within certified limits. The modified method could digest nearly all the materials tested, including the above mentioned reference materials, 2-nitrobenzoic acid (2-NBA), 4-NBA and copper(II) phthalosyanine-3, 4',4',4'-tetrasulfonic acid tetrasodium salt (CPS). The method could not digest 3-NBA.

Analysis of archaeological samples and local clays using ICP-AES, TG-DTG and FTIR techniques.

The spectrochemical and thermal analysis of different archaeological samples as bricks, terra-cotta and local clays were carried out. The concentration of major and minor elements of samples was determined by sequential inductively coupled plasma atomic emission spectrometry. The method was tested by determining Si, Al, Fe, Ca, Mg, Mn, Pb, Cu, Zn, Ti, Na and K in the standard solutions and reference material GXR-4. The precision of the determination (relative standard deviation) ranged from 0.4 to 1.54%. The clay minerals are the main materials for the production of bricks and terra-cotta figures. Thermogravimetric (TG) and differential (TG-DTG) analysis and Fourier transform infrared spectrometry (FTIR) methods can be used for the study of characteristic reactions, associated with the course of the heating. The TG-DTG curves were obtained in the temperature range 25-900 degrees C, and the dynamic experiment was carried out in the air and nitrogen atmosphere. The infrared evolved gas analysis was performed using FTIR in the dynamic nitrogen atmosphere.

The homogeneity of heavy metal deposition on glass fibre filters collected using a high-volume sampler in the vicinity of an opencast chrome mine complex at Kemi, Northern Finland.

The homogeneity of heavy metal (Cr, Ni, Cu, Fe and Cd) distribution on glass fibre filters (Munktell MG 160, 203 x 254 mm, 75 g m(-2)) collected using a high-volume sampler (Wedding & Associates) at an opencast chrome mine complex at Kemi, Northern Finland was studied. The heavy metals in the total suspended particulate (TSP) material were analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES) or graphite furnace atomic absorption spectrometry (GFAAS). The glass fibre filters were digested in a microwave oven using a mixture of aqua regia+HF acids. There was significant non-uniform distribution of heavy metals on glass fibre filters. The TSP material containing chromite was very difficult to dissolve by acid digestion. The results from X-ray fluorescence spectrometry (XRF), and from energy filtering transmission electron microscope (EFTEM) equipped with energy dispersive X-ray spectrometer (EDS), showed that insoluble residue left after microwave oven digestion with aqua regia+HF acids was probably partly due to chemical reactions occurring during microwave heating.

Estimation of environmental mobility of heavy metals using a sequential leaching of particulate material emitted from an opencast chrome mine complex.

A four-stage sequential leaching procedure was applied to assess the bioavailability and environmental mobility of heavy metals (Cr, Fe, Cu, Ni and Cd) in total suspended particulate (TSP) material emitted from an opencast chrome mine complex (Kemi, Northern Finland). TSP material was collected on glass fibre filters by a high-volume sampler, and a sequential leaching procedure was used to determine the distribution of heavy metals between the water-soluble fraction (H2O), environmentally mobile fraction (CH3COONH4), the fraction bound to carbonate and oxides (HONH3Cl + CH3COOH), and the fraction bound to silicates and organic matter, that is the environmentally immobile fraction (HNO3 + HF + HCl). The sequential leaching procedure was also applied to the certified reference materials VKI (QC Loam Soil A) and PACS-2 (Marine Sediment) to evaluate the accuracy and reproducibility of the leaching procedure. The heavy metals were determined by graphite furnace atomic absorption spectrometry (GFAAS) and flame atomic absorption spectrometry (FAAS). The concentrations of metals in the water-soluble fraction (H2O) decreased in the order Fe >Cu >Cr >Ni >Cd, and in the environmentally mobile fraction (CH3COONH4) in the order Cu >Fe >Ni >Cr >Cd.

Comparison of analytical results for chloride, sulfate and nitrate obtained from adjacent ice core samples by two ion chromatographic methods.

The anions chloride, sulfate and nitrate in nearly 500 pairs of ice core samples from the same depth were determined in a 121 m long ice core from Svalbard. The analyses were performed separately using an ion chromatograph with Dionex AS9 and AS15 columns with Na(2)CO(3) and NaOH eluents. Results showed a small (5-6 microg l(-1)) but statistically significant difference in mean concentrations for chloride and sulfate but not for nitrate. 2% of the data indicate real differences in concentrations across the ice core. Despite these differences ion information in ice core layers are comparable for ice core paleoclimate and environmental studies even though analyses are made using two different procedures.

Bone healing and mineralization, implant corrosion, and trace metals after nickel-titanium shape memory metal intramedullary fixation.

Its shape memory effect, superelasticity, and good wear and damping properties make the NiTi shape memory alloy a material with fascinating potential for orthopedic surgery. It provides a possibility for making self-locking, self-expanding, and self-compressing implants. Problems, however, may arise because of its high nickel content. The purpose of this work was to determine the corrosion of NiTi in vivo and to evaluate the possible deleterious effects of NiTi on osteotomy healing, bone mineralization, and the remodeling response. Femoral osteotomies of 40 rats were fixed with either NiTi or stainless steel (StSt) intramedullary nails. The rats were killed at 2, 4, 8, 12, 26, and 60 weeks. Bone healing was examined with radiographs, peripheral quantitative computed tomography, (pQCT) and histologically. The corrosion of the retrieved implants was analyzed by electron microscopy (FESEM). Trace metals from several organs were determined by graphite furnace atomic absorption spectrometry (GF-AAS) or by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were more healed bone unions in the NiTi than in the StSt group at early (4 and 8 weeks) time points. Callus size was equal between the groups. The total and cortical bone mineral densities did not differ between the NiTi and StSt groups. Mineral density in both groups was lower in the osteotomy area than in the other areas along the nail. Density in the nail area was lower than in the proximal part of the operated femur or the contralateral femur. Bone contact to NiTi was close. A peri-implant lamellar bone sheet formed in the metaphyseal area after 8 weeks, indicating good tissue tolerance. The FESEM assessment showed surface corrosion changes to be more evident in the StSt implants. There were no statistically significant differences in nickel concentration between the NiTi and StSt groups in any of the organs. NiTi appears to be an appropriate material for further intramedullary use because it has good biocompatibility in bone tissue.