Thermoluminescent composites of sintered synthetic-topaz/in situ corundum for dosimetry by a novel reversible process.

Topaz (Al2F1·44(OH)0·56SiO4)/corundum (Al2O3) composites were prepared by a facile and novel reversible process from the sintering of synthetic topaz and AlF3 powders, with corundum formed in situ into the topaz matrix. The corundum formation reaction occurs in the temperature range 875-975 °C, from 40 min sintering time, obtaining the topaz- Al2F1·44(OH)0·56SiO4/corundum- Al2O3 composites. Although sintering temperature and time increment lead to higher corundum formation in the topaz matrix (78.4 wt % Al2O3 at 975 °C for 60 min), longer residence times give place to corundum percentage decrease due to topaz reconversion. The composites' microstructure is characterized by a rectangular bar with stacked pyramidal ends and polycrystals of hexagonal plates for topaz and corundum, respectively. For the topaz/corundum composites, the maximum density was 3.05 g/cm3 (17 % porosity) for specimens sintered at 925 °C for 20 min. The glow curves of the topaz/in situ corundum composite sintered at 975 °C and 0 min dwell time show thermoluminescent peaks between 180 and 250 °C, useful for dosimetric applications. The most helpful peak (at 221 °C) in the topaz/corundum composite's glow curves determined by computational deconvolution is sharp and exhibits the highest thermoluminescent response. Dose-response analysis of the composite (sintered at 975 °C for 0 min) with the best thermoluminescent response revealed two ranges of linear behavior, the first from 2 to 200 mGy, with an adjustment of 99.9 % and the second in the range 5-300 Gy (99.8 % fitting). The thermoluminescent response improvement of the topaz/corundum composites is attributed to the corundum formed in situ during sintering. Fading rate studies of the composite with the best sintering treatment revealed a signal decrease of 4 % after 15 days, which remained constant for up to 30 days, and 8 % after 60 days. The kinetic parameters, kinetics order (b), activation energy (E), and frequency factor (s) determined using the glow peak shape method showed second-order kinetics. The topaz/corundum composite with the best TL response (975 °C, 0 min) presents an effective atomic number (Zeff) of 11.74. The detection of lower doses (mGy) and the linear response at higher doses (Gy) of beta 90Sr, together with the other thermoluminescent properties, suggest that the topaz/corundum composites sintered at 975° for 0 min dwell time may find application in radiotherapy, geological dating, and environmental dosimetry.

Generation of effective zinc-deficient agar-solidified media allows identification of root morphology changes in response to zinc limitation.

Earlier, we demonstrated that transcript levels of METAL TOLERANCE PROTEIN2 (MTP2) and of HEAVY METAL ATPase2 (HMA2) increase strongly in roots of Arabidopsis upon prolonged zinc (Zn) deficiency and respond to shoot physiological Zn status, and not to the local Zn status in roots. This provided evidence for shoot-to-root communication in the acclimation of plants to Zn deficiency. Zn-deficient soils limit both the yield and quality of agricultural crops and can result in clinically relevant nutritional Zn deficiency in human populations. Implementing Zn deficiency during cultivation of the model plant Arabidopsis thaliana on agar-solidified media is difficult because trace element contaminations are present in almost all commercially available agars. Here, we demonstrate root morphological acclimations to Zn deficiency on agar-solidified medium following the effective removal of contaminants. These advancements allow reproducible phenotyping toward understanding fundamental plant responses to deficiencies of Zn and other essential trace elements.

Regulation of acetylation of plant cell wall components is complex and responds to external stimuli.

Previously, we reported that the allelic de-etiolated by zinc (dez) and trichome birefringence (tbr) mutants exhibit photomorphogenic development in the dark, which is enhanced by high Zn. TRICHOME BIREFRINGENCE-LIKE proteins had been implicated in transferring acetyl groups to various hemicelluloses. Pectin O-acetylation levels were lower in dark-grown dez seedlings than in the wild type. We observed Zn-enhanced photomorphogenesis in the dark also in the reduced wall acetylation 2 (rwa2-3) mutant, which exhibits lowered O-acetylation levels of cell wall macromolecules including pectins and xyloglucans, supporting a role for cell wall macromolecule O-acetylation in the photomorphogenic phenotypes of rwa2-3 and dez. Application of very short oligogalacturonides (vsOGs) restored skotomorphogenesis in dark-grown dez and rwa2-3. Here we demonstrate that in dez, O-acetylation of non-pectin cell wall components, notably of xyloglucan, is enhanced. Our results highlight the complexity of cell wall homeostasis and indicate against an influence of xyloglucan O-acetylation on light-dependent seedling development.

Unintentional pediatric submersion-injury-related hospitalizations in the United States, 2003.

The objective of this study was to examine the demographic characteristics and hospital resource utilization of submersion-injury-related hospitalizations among persons < or =20 years of age in the USA in 2003. All 1475 pediatric submersion-injury-related hospital discharges in the Kids' Inpatient Database were identified by ICD-9-CM diagnosis code or external cause of injury code. These cases represent an estimated 2490 pediatric submersion-injury-related hospitalizations nationwide. Inpatient costs for these estimated hospitalizations were approximately $10 million. The overall pediatric submersion-injury-related rate of hospitalization was 3.0 per 100,000 persons. Children aged 0-4 years had the highest rate of hospitalization (7.7 per 100,000 persons). Children with permanent submersion-injury-related morbidity accounted for 5.8% of hospital admissions and 37.3% of hospital costs in our study, and children with submersion-injury-related in-hospital death accounted for 11.6% of hospital admissions and 20.0% of hospital costs in our study. Prevention of submersion injury using focused, proven strategies deserves increased attention.

Merkel cell carcinoma can be distinguished from metastatic small cell carcinoma using antibodies to cytokeratin 20 and thyroid transcription factor 1.

AIM: To investigate whether immunohistochemical staining for cytokeratin 20 (CK20) and thyroid transcription factor 1 (TTF-1) is useful in distinguishing Merkel cell carcinomas (MCCs) from metastatic small cell carcinomas (SCCs). METHODS: Eleven cases of MCC and 10 of lung SCC were stained for CK20 and TTF-1. RESULTS: Ten of 11 MCCs stained with the antibody to CK20. None was positive for TTF-1. No SCC stained with anti-CK20 and all stained strongly with anti-TTF-1. CONCLUSIONS: The use of both anti-CK20 and anti-TTF-1 can reliably distinguish between MCC and metastatic SCC, thus avoiding the need for a detailed clinical investigation of patients with MCC in whom metastatic SCC must be excluded.

Sun protection provided by ladies stockings.

Bowen's disease, squamous and basal cell carcinoma, and malignant melanoma occur more frequently on the lower leg of women compared with men, presumably because of increased solar ultraviolet radiation (UVR) exposure as a consequence of dress. While it is apparent from simple observation that stockings are transparent to light, systematic data on UV transmission through stockings are lacking. The purpose of this study was to measure the spectral transmission of UVR through a range of thickness and colours of plain-knit ladies stockings, and to use these data to calculate the sun protection factor (SPF). We found that SPFs increased from about 1.5 to 3.0 for black stockings ranging from 10 to 40 denier; there were statistically significant differences in SPFs with colour (higher for darker colours) and site (higher at the distal calf than at the proximal calf); and for every colour and denier of stocking tested, UVA and UVB were absorbed equally. We conclude that the most popular type of stocking (15 denier) provides an SPF of less than 2, and that women who require photoprotection to the legs be advised to wear trousers or at least a 40 denier stocking.

Necrolytic migratory erythema and zinc deficiency.

Necrolytic migratory erythema (NME) is an uncommon condition classically associated with high plasma levels of circulating glucagon and a glucagonoma. We report a patient with cirrhosis who showed clinical and histological features of NME. Investigation revealed normal glucagon levels without evidence of glucagonoma. Serum zinc levels were below the normal range and zinc supplementation resulted in rapid and complete resolution of the eruption.

Angiosarcoma arising in a chronically lymphoedematous leg.

Cutaneous angiosarcoma is a rare aggressive tumour of capillary and lymphatic endothelial cell origin. It presents as multiple purple and red papules and nodules on the head and neck or the extremities. We report an 86-year-old woman with angiosarcoma arising on her chronically lymphoedematous right leg. The lymphoedema, secondary to chronic immobility, had developed gradually over 40 years. No other family members had lymphoedema. The patient presented with a plaque of friable tumour tissue on the lower right leg and dorsum of the foot, and satellite lesions on the knee and groin which initially appeared to be petechial haemorrhages. The satellite lesions in the groin grew into tumour nodules. There was no evidence of a preceding malignancy, nor any operative intervention to the affected limb or abdomen. Histological examination of all tumour specimens revealed moderately to poorly differentiated angiosarcoma. She died within 5 months of the first appearance of the skin nodules.