Authors:L. Vanmiddlesworth, J. Handle and P. Johns
Iodine-129 may have no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioiodine contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer living near a nuclear reprocessing facility have contained 129I, which are 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I, may be helpful to evaluate past radiation hazard from fission products.
appeared in the Journal of Radioanalytical and Nuclear Chemistry, Vol. 243, No. 2 (2000) 467–472.During the electronic submission of the paper the file was damaged, and parts were left out. In order to correct this, we publish the correct paper as a whole.Iodine-129 may be no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioactive contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer, living near a nuclear reprocessing facility have contained 129I which is 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I may be helpful to evaluate past radiation hazard from fission products.
Authors:Denis A. Brosnan, John P. Sanders and Stephanie A. Hart
Thermal analysis techniques have been used in characterizing building materials from significant historic properties in the Charleston, South Carolina area. Determining the chemical and physical effects of deterioration resulting from long periods of exposure is a first step in formulating preservation strategies. In this regard, simultaneous thermal analysis coupled with evolved gas analysis has been used to study reactions between air, seawater, and masonry materials. Further, the traditional petrographic identification of mortar composition is greatly facilitated through use of thermal analysis. Simultaneous thermal analysis allows for an exact determination of the calcium carbonate content in mortars as an alternative to the use of an inferred value based on chemical analysis data. The partial dissolution of calcium carbonate in the presence of sea salt is a major deterioration process. Further, natural cements manufactured in the United States are identified, in part, based on their thermogravimetric (TG) traces and their evolved gases. The data indicates that natural cements form some carbonate phases in addition to the major hydrate phases. Clay bricks are found to exhibit interaction with sea water, with uptake of bicarbonate suggested. Additionally, there is evidence of re-hydroxylation in the 160 year old bricks. The bricks made in coastal zones contain a considerable free silica fraction that is composed of a small percentage of cristobalite. The silica content of the clay bricks is seen to result in very high thermal expansion coefficients in the area of 10 × 10−6 to 12 × 10−6 K−1. These studies provide guidance in restoration efforts where authenticity of cements is important. In the event that replacement bricks are required, matching the thermal expansion coefficient of the original bricks is a requirement for preservation of the masonry structure.
Authors:L. Hulett, John Dale, H. Dunn and P. Murty
The purpose of this paper is to demonstrate that complicated mixtures of solids can be characterized to a rather high degree
if a coordinated examination by non-destructive methods is used. The techniques discussed are X-ray fluorescence, scanning
electron microscopy, photoelectron spectroscopy, transmission electron microscopy, electron diffraction and X-ray diffraction.
The application of these methods to the characterization of corrosion scale on an inconel coupon is illustrated. The types
of information accumulated were elemental composition, chemical forms of elements, special distributions of elements and compounds
in the scale, sizes of particles that made up the scale, variations in composition of particle surfaces from that of their
interiors, and composition of scale-alloy interface.
Authors:G. Brownstein, C. Johns, A. Fletcher, D. Pritchard and P. D. Erskine
Ecotones, representing the transition zones between species or communities, have been suggested as focal points for detecting early shifts in vegetation composition due to anthropogenic impact. Here we examined if changes in ecotone location or properties can be used as reliable indicators of hydrological change in temperate wetland communities. We examined 38 woodland-wetland-woodland transitions, distributed across four sites with different anthropogenic disturbance histories and hydrological traits. We tested whether: 1) the ecotones are associated with environmental gradients, and 2) the location or properties of these ecotones change with disturbance history. Well-defined ecotones were associated with steep gradients in soil depth and soil moisture. Most ecotones showed a change in vegetation from hydrophytic to dryland species. There was also some evidence that in highly disturbed sites the link between ecotones and environmental gradients was less apparent. By sampling across boundaries we can better understand the factors controlling the distribution of species. This allows us to make better predictions about the impacts of anthropogenic change in wetland communities. By investigating the transitions between different vegetation communities we were able to highlight key indicators that could be used to monitor these ecologically sensitive and diverse wetland communities.
Authors:M. Jose John, K. Muraleedharan, V. M. Abdul Mujeeb, M. P. Kannan and T. Ganga Devi
Pure and doped samples of sodium oxalate (Na2C2O4) were subjected to pre-compression and their thermal decomposition kinetics was studied at five different temperatures in the range 783–803 K under isothermal conditions by thermogravimetry. The pre-compressed samples decomposed in two stages governed by different rate laws; the Prout–Tompkins model best describes the acceleratory stage of the decomposition while the decay region is best fitted with the contracting cylinder model as in the case of uncompressed sodium oxalate samples. The rate constants k1 and k2 of the acceleratory and deceleratory stages of the thermal decomposition were dramatically decreased on pre-compression. However, the activation energies, evaluated by model fitting kinetic method, E1 and E2 for the respective stages of decomposition remained unaltered by pre-compression. The results favor ionic diffusion mechanism proposed earlier on the basis of doping studies.
Authors:M. Sivasamy, M. Aparna, J. Kumar, P. Jayaprakash, V. Vikas, P. John, R. Nisha, Satyaprakash, K. Sivan and E. Punniakotti
Nearly twenty thousand wheat lines were phenotyped for the presence of leaf tip necrosis (LTN), a phenotypic trait linked to adult plant leaf rust resistance (APR) genes, viz. Lr34, Lr46 and Lr67 having pleiotropic association with multiple disease resistance genes. Thirty-six lines showed varied expression of LTN and moderate level of leaf rust severity at adult plant stage with slow rusting (disease progress at a retarded rate). Seedling resistance test (SRT) revealed susceptible and mixed infection types, a characteristic of adult plant resistance (APR) genes. Further molecular confirmation for the presence of these genes using available microsatellite markers revealed that of the 36 lines, five lines carried Lr46+ alone and five other lines carried Lr67+ alone. Seven lines carried the combination of Lr34+ and Lr67+ while six lines confirmed to carry the combination of Lr46+ and Lr67+. Remarkably three lines carried all the three APR genes, viz. Lr34+, Lr46+ and Lr67+. All these stocks can be a source of APR multiple disease resistance genes. Ten lines were not confirmed to carry any of the genes but still had LTN and SRT results showing an infection type typical of APR genes and these can be the source of identifying newer APR genes. The resistance based on minor APR genes when combined with a few additional minor genes in the background of high yielding cultivars is expected to have high level of race non-specific resistance and to be durable.
Authors:Oche O. Agbaji, Nimzing G. Ladep, Patricia Agaba, Bitrus P. Badung, Monday L. Danung, Godwin Imade, John A. Idoko, Rob Murphy and Phyllis Kanki
There is a rising trend of hepatitis B co-infection among HIV positive individuals and this may negatively impact their morbidity and mortality. This study analyzed HBsAg prevalence, its demographic distribution and relationship to the immunological and viral load status of HIV positive cohort in Jos.
This was a cross-sectional study conducted at the antiretroviral treatment centre in Jos between August 2004 and April 2005. Biodata of 1042 consenting HIV positive patients were obtained. Blood samples obtained from them were tested for hepatitis B surface antigen by Enzyme Linked Immunosorbent Assay. CD4 cell count was done by flow cytometry (Partec, Germany) and viral load by PCR techniques (Roche Amplicor 1.5). The data obtained were analyzed using Epi Info 2004 statistical software.
One hundred and sixty seven (16%) of the 1042 patients were reactive to HBsAg. Thirteen (22.4%) of 58 divorced patients had the highest co-infection rate. Ninety-seven (14.2%) out of 681 females were co-infected with hepatitis B, while seventy (19.4%) out of 361 males had the co-infection. Most of the patients at the AIDS stage of the HIV infection were co-infected with hepatitis B. The median HIV viral load of HBsAg-positive patients was higher than that of non-HBV co-infected patients.
This study showed a high HBsAg prevalence among our patients with a significant male preponderance. This may have a negative impact on the CD4 recovery and viral load reduction of the patients on treatment.
Authors:M. Sivasamy, M. Aparna, J. Kumar, P. Jayaprakash, V.K. Vikas, P. John, R. Nisha, K. Srinivasan, J. Radhamani, S.R. Jacob, S. Kumar, Satyaprakash, K. Sivan, E. Punniakotti, R.K. Tyagi and K.C. Bansal