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X-ray absorption spectroscopy is aspectroscopic in situ technique whichcombines the high penetration strength inherentto X-rays with the advantages of local probetechniques, such as no need for long rangeorder and the ability to obtain information onselected sites of a given sample only.Consequently, this technique is applicable to abroad variety of scientific questions,including many applications in biological,agricultural and environmental sciences. Thefirst part of this review provides anintroduction to the method, whose applicationto a broad variety of problems is discussed indetail, especially XAS of sulfur in biologicalsystems. In the second part new ideas forfurther experiments using this versatile methodare presented.[PUBLICATION ABSTRACT]

MoO₃ was dispersed onto mesoporous SBA-15 by using ammonium heptamolybdate as MoO₃ source. The formation of MoO₃ was carried out by heating the loaded material to 500 °C for 3 h in air. Below 13 wt% Mo loading, no reflections of MoO₃ occur in the X-ray powder patterns and even for high MoO₃ contents, the intensities of the reflections are much lower than expected for fully crystalline material. A detailed XAFS analysis reveals that at low Mo contents, the metastable hexagonal modification of MoO₃ is formed despite the high calcination temperature of 500 °C. It is highly likely that the nanosize of the particles and the interaction between MoO₃ and SBA-15 stabilize the metastable modification of the material. Nitrogen physisorption experiments show the typical type-IV isotherms indicating that the mesoporosity of the materials is preserved despite the large amount of MoO₃. Transmission electron micrographs demonstrate the presence of MoO₃ inside the SBA-15 support. The Raman spectra display a remarkable size-dependent intensity loss and several features give evidences for a bond formation between nano-sized MoO₃ particles and the silica support. Moreover, the spectroscopic details suggest the formation of (MoO₃)ₙ oligomers. MoO₃ nanoparticles are successfully introduced into the pores of mesoporous SBA-15. Up to about 13 wt% Mo the material is amorphous and even for higher loadings a large amount of MoO₃ is still not crystalline. Nitrogen physisorption and transmission electron microscopy evidences that the mesoporosity of the material is retained. At low Mo loading, the metastable hexagonal modification of MoO₃ appears to be stabilized by the interaction with the SBA-15 support material (XAFS).

MoO sub(3) was dispersed onto mesoporous SBA-15 by using ammonium heptamolybdate as MoO sub(3) source. The formation of MoO sub(3) was carried out by heating the loaded material to 500 C for 3 h in air. Below 13 wt% Mo loading, no reflections of MoO sub(3) occur in the X-ray powder patterns and even for high MoO sub(3) contents, the intensities of the reflections are much lower than expected for fully crystalline material. A detailed XAFS analysis reveals that at low Mo contents, the metastable hexagonal modification of MoO sub(3) is formed despite the high calcination temperature of 500 C. It is highly likely that the nanosize of the particles and the interaction between MoO sub(3) and SBA-15 stabilize the metastable modification of the material. Nitrogen physisorption experiments show the typical type-IV isotherms indicating that the mesoporosity of the materials is preserved despite the large amount of MoO sub(3). Transmission electron micrographs demonstrate the presence of MoO sub(3) inside the SBA-15 support. The Raman spectra display a remarkable size-dependent intensity loss and several features give evidences for a bond formation between nano-sized MoO sub(3) particles and the silica support. Moreover, the spectroscopic details suggest the formation of (MoO sub(3)) sub(n) oligomers. Graphical Abstract: MoO sub(3) nanoparticles are successfully introduced into the pores of mesoporous SBA-15. Up to about 13 wt% Mo the material is amorphous and even for higher loadings a large amount of MoO sub(3) is still not crystalline. Nitrogen physisorption and transmission electron microscopy evidences that the mesoporosity of the material is retained. At low Mo loading, the metastable hexagonal modification of MoO sub(3) appears to be stabilized by the interaction with the SBA-15 support material (XAFS).

Cetyl trimethyl ammonium bromide (CTAB) stabilized gold(III) salt in chloroform was reduced using NaBH4 in the presence of commercially available methanethiol-polyphoResinTM to obtain polystyrene micro beads with gold nanoparticles on their surface. X-ray Absorption Near Edge Spectra (XANES) of Au and S revealed S-Au bonding state. TEM studies coupled with Selected Area Electron Diffraction(SAED) patterns revealed the morphology of the Au nanoparticles on the surface of the micro beads.

Hashimoto's thyroiditis is a common autoimmune disorder of the thyroid gland. It has been linked to infections with hepatitis C, EBV, HTLV-1, and Yersinia enterocolitica . As parvovirus B19 has been associated with a wide spectrum of autoimmune diseases, we investigated the potential role of B19 infection in inducing Hashimoto's thyroiditis. Serum samples derived from 73 children and adolescents with Hashimoto's thyroiditis and from 73 age-matched controls were included in the study. The mean age of disease manifestation was 10 y 7 mo. All samples were analyzed for the presence of viral DNA and for antibodies against VP1, VP2, and NS1 proteins. VP1- and VP2-specific antibodies were present in 38 patients (52%) and 43 controls (59%; N.S.). NS1-specific antibodies were detectable in 23 patients (32%) and 19 controls (26%; N.S.). Parvovirus B19 DNA was detectable in 9 patients (12%) and 2 controls (3%; p < 0.03), indicating recent B19-infection. A negative correlation between disease duration and the detection of viral DNA was seen. The mean disease duration in B19-DNA-positive patients was 6 mo, compared to 29 mo in the remainder ( p < 0.01). There is strong evidence that acute parvovirus B19 infections are involved in the pathogenesis of some cases of Hashimoto's thyroiditis.

Children with rheumatic oligo- and polyarthritis frequently establish persistent parvovirus B19 infections, which may be associated with the production of antiphospholipid antibodies. Reported in this paper are the data of five girls with polyarticular rheumatic diseases of different types and persistent parvovirus B19 infection associated in four cases with the presence of antibodies against phospholipids. Clinical parameters, virus load, and antiphospholipid-IgG levels were determined during an observation period up to 92 months. In two patients, erythema infectiosum preceded the development of arthritis and B19 viremia persisted. Two other girls showed antibodies against parvoviral structural proteins at time of the manifestation of the rheumatic disease. Subsequent samples also revealed persistent B19 infection. In the fifth patient, parvovirus B19-specific IgG antibodies were detected for the first time after 120 months of progressing disease at an age of 11 1/2 years. Five years later, quantitative polymerase chain reaction (PCR) revealed viral DNA. In a synovial tissue specimen subsequently obtained, parvovirus B19 structural proteins could be detected by immunohistochemistry. Three of five patients recovered completely without severe sequels. One patient is in remission under immunosuppressive therapy. The fifth patient suffers from progressive erosions despite intensive therapeutical efforts. In consequence, parvovirus B 19 should generally be taken into consideration as a trigger of various forms of juvenile arthritis and persistence of infection should be evaluated.