Genotyping of European Toxoplasma gondii strains by a new high-resolution next-generation sequencing-based method.

PURPOSE: A new high-resolution next-generation sequencing (NGS)-based method was established to type closely related European type II Toxoplasma gondii strains. METHODS: T. gondii field isolates were collected from different parts of Europe and assessed by whole genome sequencing (WGS). In comparison to ME49 (a type II reference strain), highly polymorphic regions (HPRs) were identified, showing a considerable number of single nucleotide polymorphisms (SNPs). After confirmation by Sanger sequencing, 18 HPRs were used to design a primer panel for multiplex PCR to establish a multilocus Ion AmpliSeq typing method. Toxoplasma gondii isolates and T. gondii present in clinical samples were typed with the new method. The sensitivity of the method was tested with serially diluted reference DNA samples. RESULTS: Among type II specimens, the method could differentiate the same number of haplotypes as the reference standard, microsatellite (MS) typing. Passages of the same isolates and specimens originating from abortion outbreaks were identified as identical. In addition, seven different genotypes, two atypical and two recombinant specimens were clearly distinguished from each other by the method. Furthermore, almost all SNPs detected by the Ion AmpliSeq method corresponded to those expected based on WGS. By testing serially diluted DNA samples, the method exhibited a similar analytical sensitivity as MS typing. CONCLUSION: The new method can distinguish different T. gondii genotypes and detect intra-genotype variability among European type II T. gondii strains. Furthermore, with WGS data additional target regions can be added to the method to potentially increase typing resolution.

Sustainable Development Goals' health-related indicators for Brazil and Ecuador: an analysis for the period of 1990-2019.

OBJECTIVE: This article aims to analyse the evolution of 40 Sustainable Development Goals' (SDGs) health-related indicators in Brazil and Ecuador from 1990 to 2019. STUDY DESIGN: Epidemiological study of long-term trends in 40 SDGs' health-related indicators for Brazil and Ecuador from 1990 to 2019, using estimates from the Global Burden of Disease Study. METHODS: Forty SDGs' health-related indicators and an index from 1990 to 2017 for Brazil and Ecuador, and their projections up to 2030 were extracted from the Institute for Health Metrics and Evaluation's Global Burden of Disease website and analysed. The percent annual change (PC) between 1990 and 2019 was calculated for both countries. RESULTS: Both countries have made progress on child stunting (Brazil: PC = -38%; Ecuador: PC = -43%) and child wasting prevalences (Brazil: PC = -42%; Ecuador: PC = -41%), percent of vaccine coverage (Brazil: PC = +215%; Ecuador: PC = +175%), under-5 (Brazil: PC = -75%; Ecuador: PC = -60%) and neonatal mortality rates (Brazil: PC = -69%; Ecuador: PC = -51%), health worker density per 1000 population (Brazil: PC = +153%; Ecuador: PC = +175%), reduction of neglected diseases prevalences (Brazil: PC = -40%; Ecuador: PC = -58%), tuberculosis (Brazil: PC = -27%; Ecuador: PC = -55%) and malaria incidences (Brazil: PC = -97%; Ecuador: PC = -100%), water, sanitation and hygiene mortality rates (Brazil and Ecuador: PC = -89%). However, both countries did not show sufficient improvement in maternal mortality ratio to meet SDGs targets (Brazil: PC = -37%; Ecuador: PC = -40%). Worsening of indicators were found for violence, such as non-intimate partner violence for both countries (Brazil: PC = +26%; Ecuador: PC = +18%) and suicide mortality rate for Ecuador (PC = +66%), child overweight indicator for Brazil (PC = -67%), disaster mortality rates (Brazil: PC = +100%; Ecuador: PC = +325%) and alcohol consumption (Brazil: PC = +46%; Ecuador: PC = +35%). CONCLUSIONS: Significant improvements are necessary in both countries requiring the strengthening of health and other policies, particularly concerning the prevention and management of violence and alcohol consumption, and preparedness for dealing with environmental disasters.

A ring trial to harmonize Toxoplasma gondii microsatellite typing: comparative analysis of results and recommendations for optimization.

A ring trial among five European laboratories was organized to reach consistency in microsatellite (MS) typing of the zoonotic parasite Toxoplasma gondii. Three sample sets were circulated and analyzed by each laboratory following a previously published method that is based on fragment length polymorphism of 15 MS markers. The first sample set compared typing results in general and focused on effects of DNA concentration; the second sample set focused on the polymorphic fingerprinting markers that can differentiate T. gondii strains within the same archetypal lineage; and the third set focused on non-archetypal genotypes. Methodological variations between laboratories, including the software programs used to determine MS fragment length, were collated using a questionnaire. Overall, lineage-level typing results reached a high level of agreement, especially in samples with the highest DNA concentrations. However, laboratory-specific differences were observed for particular markers. Major median differences in fragment length, of up to 6 base pairs, were related to the fluorophore used to label fragment-specific primers. In addition, primer pairs with identical sequences obtained from different suppliers resulted in fragments of differing length. Furthermore, differences in the way the sequencing profiles were assessed and interpreted may have led to deviating results in fragment length determination. Harmonization of MS typing, for example, by using the same fluorophores or by numerical adjustments applied to the fragment-lengths determined, could improve the uniformity of the results across laboratories. This is the first interlaboratory comparison, providing guidelines (added as a supplement) for the optimization of this technique.

Sarcocystis spp. diversity in the roe deer (Capreolus capreolus) from Lithuania and Spain.

The roe deer (Capreolus capreolus) has been identified as an intermediate host for six known Sarcocystis species, S. capreolicanis, S. entzerothi, S. gracilis, S. linearis, S. oviformis, and S. silva. In this study, we identified Sarcocystis species in the diaphragm and tongue muscles from the Lithuanian and Spanish roe deer, respectively, on the basis of a microscopic examination and DNA analysis. A total of 43 and 27 sarcocysts were isolated and characterized from the Lithuanian and Spanish roe deer, respectively. Overall six Sarcocystis species were identified in roe deer from Lithuania, and only three of them, S. gracilis, S. linearis, and S. silva were found to have infecting animals from Spain. The current paper represents first molecular results of Sarcocystis species in the Spanish roe deer. Furthermore, transmission electron microscopy examination revealed specific wall structure of sarcocysts studied, S. linearis was characterized by ribbon-like villar protrusions (vp) (type 8a), and S. oviformis was distinguished by elongated vp resembling spades or mushroom-like structures (type 39). Based on 18S rDNA and cox1 sequences, Sarcocystis species from the roe deer showed considerable intraspecific genetic variability. However, similar values of intraspecific genetic variation were estimated at both genes analysed. The highest variability was observed for S. capreolicanis and S. linearis in both genes and for S. silva at cox1. Consequently, the level of genetic variability of Sarcocystis from the roe deer varied depending on species rather than on gene analysed or geographical area.

Increased CD127+ and decreased CD57+ T cell expression levels in HIV-infected patients on NRTI-sparing regimens.

BACKGROUND: NRTIs-sparing regimens exert favourable profiles on T-cell homeostasis associated parameters. Our aim was to analyze the effect of NRTIs sparing regimen (NRTI-sparing-cART) vs NRTIs-containing regimen (NRTI-cART), on T-cell homeostasis associated parameters in naive HIV-infected patients. METHODS: Biomarkers of cell survival (CD127) and replicative senescence (CD57), were measured by multiparametric flow cytometry for T-cell phenotyping on peripheral blood mononuclear cells (PBMCs) samples just before (baseline) and after 48 weeks of undetectable viral load in patients on NRTI-sparing-cART (N = 13) and NRTI-cART (N = 14). After 48 weeks a subgroup of patients (n = 5) on NRTI-cART switched to NRTI-sparing-cART for another additional 48 weeks. In vitro assays were performed on PBMCs from HIV-uninfected healthy donors exposed or not to HIV. To analyze the independent factors associated with type of cART bivariate and stepwise multivariate analysis were performed after adjusting for basal CD4+, CD8+ and nadir CD4+ T-cell counts. RESULTS: After 48 weeks of a NRTI-sparing-cART vs NRTI-cART patients have higher effector memory (EM) CD4+ CD127+ T-cell levels, lower EM CD4+ CD57+ T-cell levels, higher CD8+ CD127+ T-cell levels, lower CD8+ CD57+ T-cell levels and higher memory CD8+ T-cell levels. This effect was confirmed in the subgroup of patients who switched to NRTI-sparing-cART. In vitro assays confirmed that the deleterious effect of a NRTIs-containing regimen was due to NRTIs. CONCLUSIONS: The implementation of NRTI-sparing regimens, with a favourable profile in CD127 and CD57 T-cell expression, could benefit cART-patients. These results could have potential implications in a decrease in the number of Non-AIDS events.

RUNX1 amplification in AML with myelodysplasia-related changes and ring 21 chromosomes.

Ring 21 is an unstable structural abnormality of chromosome 21 that can lead to RUNX1 gene amplification. We present a unique case with a carrier patient of a constitutional ring chromosome 21 (partial monosomy and trisomy 21) with dysmorphic features and congenital malformations phenotype, who developed acute myeloid leukaemia with myelodysplasia-related changes and two ring 21 chromosomes with RUNX1 amplification. The patient's constitutional ring 21 chromosome showed alterations in tumour suppressor genes, and oncogenes, but not in RUNX1. RUNX1 gene expression at acute myeloid leukaemia diagnosis, showed no upregulation, so other genes may also be the genetic amplification targets in this patient. Copyright © 2016 John Wiley & Sons, Ltd.

Phenotype and Polyfunctional Deregulation Involving Interleukin 6 (IL-6)- and IL-10-Producing Monocytes in HIV-Infected Patients Receiving Combination Antiretroviral Therapy Differ From Those in Healthy Older Individuals.

BACKGROUND: Despite the relevance of monocytes as promoters of the inflammatory response, whether human immunodeficiency virus (HIV) infection induces premature age-related changes to the phenotype and function of monocytes or whether these alterations are different and/or specifically driven by HIV remains to be mechanistically determined. METHODS: We assayed the activation phenotype and the responsiveness in vitro to Toll-like receptor (TLR) agonists in classical, intermediate, and nonclassical subsets of monocytes by assessing intracellular interleukin 1α (IL-1α), IL-1ß, interleukin 6 (IL-6), interleukin 8, tumor necrosis factor α, and interleukin 10 (IL-10) production in 20 HIV-infected patients receiving combination antiretroviral therapy (cART) and 2 groups of uninfected controls (20 age-matched young individuals and 20 older individuals aged >65 years). RESULTS: HIV-infected patients showed a more activated phenotype of monocytes than older controls. Regarding functionality, under unstimulated conditions HIV-infected patients showed a higher percentage of classical monocytes producing IL-6 and IL-10 than control subjects. The percentage of cells with production of multiple cytokines (polyfunctionality), including IL-10, in response to TLR agonists was greater among HIV-infected patients than among control subjects. CONCLUSIONS: Inflammatory alterations associated with monocytes during HIV infection are different from those in aging individuals. This monocyte dysfunction, mainly characterized by high levels of IL-6- and IL-10-producing monocytes, may have clinical implications in HIV-infected patients that are different from those in aging individuals.

In the United States, negligible rates of zoonotic sarcocystosis occur in feral swine that, by contrast, frequently harbour infections with Sarcocystis miescheriana, a related parasite contracted from canids.

Transmission of pathogens between domestic and wild life animals plays an important role in epidemiology. Feral pig populations are increasing and expanding in the USA, and may constitute a risk to non-biosecure domestic pig facilities by serving as reservoirs for pathogens. We surveyed, for Sarcocystis infection, the myocardium of 1006 feral pigs (Sus scrofa) trapped or hunted in 29 states during the Comprehensive Feral Swine Disease Surveillance Program of the USDA's Animal and Plant Health Inspection Service, Wildlife Services unit during 2012-2014. Sarcocysts were detected in histological sections of 25% (251/1006) of myocardium with an average parasitic load/intensity of infection of 3.03 sarcocysts/section (1.5×0.7 cm), and higher prevalence of myocarditis in severe infections. Microscopic examination of pepsin digests of 147 hearts revealed a higher prevalence of Sarcocystis bradyzoites (49%, 72/147) than when diagnosed by histology. A fragment of Sarcocystis 18S rRNA was amplified and digested with a restriction endonuclease, revealing a pattern consistent with Sarcocystis miescheriana in all 44 selected samples. Sequencing 31 of these 44 isolates confirmed their correspondence to S. miescheriana. Thus, S. miescheriana infection, but not the zoonotic parasite Sarcocystis suihominis, appears to be prevalent and widespread in feral pigs in the USA.

A review of sarcocystosis in camels and redescription of Sarcocystis cameli and Sarcocystis ippeni sarcocysts from the one-humped camel (Camelus dromedarius).

There is considerable confusion concerning Sarcocystis species in camels. Five species: Sarcocystis cameli, Sarcocystis ippeni, Sarcocystis camelicanis, Sarcocystis camelocanis and Sarcocystis miescheri were named with inadequate descriptions and no type specimens. Here, we review literature on sarcocystosis in camels worldwide and redescribe structure of S. cameli and S. ippeni sarcocysts by light- and transmission electron microscopy (LM and TEM). Eight sarcocysts from the oesophagi of two camels (Camelus dromedarius) from Egypt were studied. By LM, all sarcocysts were thin-walled with barely visible projections on the cyst walls. By TEM, two structurally distinct sarcocysts were recognized by unique villar protrusions (vp) not found in sarcocysts from any other host. Sarcocysts of S. cameli had vp of type 9 j. The sarcocyst wall had upright slender vp, up to 3.0 µM long and 0.5 µM wide; the total thickness of the sarcocyst wall with ground substance (gs) layer was 3.5 µM. On each vp, there were rows of knob-like protrusions that appeared to be interconnected. The vp had microtubules that originated at midpoint of the gs and continued up to the tip; microtubules were smooth, without any granules or dense areas. Bradyzoites were approximately 14-15 × 3-4 µM in size with typical organelles. Sarcocystis ippeni sarcocysts had type 32 sarcocyst wall characterized by conical vp with an electron dense knob. The total thickness of the sarcocyst wall (from the base of gs to vp tip) was 2.3-3.0 µM. The vp were up to 1.2 µM wide at the base and 0.25 µM at the tip. Microtubules in vp originated at midpoint of gs and continued up to tip; microtubules were criss-crossed, smooth and without granules or dense areas. Bradyzoites were 12.0-13.5 × 2.0-3.0 µM in size. Sarcocystis camelicanis, S. camelocanis and S. miescheri are considered invalid.

Redescription of Sarcocystis fusiformis sarcocysts from the water buffalo (Bubalus bubalis).

Four valid species of Sarcocystis have been reported from the water buffalo (Bubalus bubalis): Sarcocystis fusiformis, Sarcocystis buffalonis, Sarcocystis levinei and Sarcocystis dubeyi. Here, we redescribe structure of S. fusiformis sarcocysts by scanning and transmission electron microscopy (SEM, TEM). Twenty-one macroscopic sarcocysts from oesophagus of the water buffalo in Egypt were examined by light microscopy, SEM and TEM. The sarcocyst wall was up to 9 µm thick, depending on the section and the technique. In 5 µm paraffin-embedded sections, the sarcocyst wall was indistinct, 2-5 µm thick and appeared smooth. In 1 µm plastic-embedded sections stained with toluidine blue, the sarcocyst wall was 2.5-5.2 µm thick and had branched villar protrusions (vp)-like branches of a dead tree. By SEM, the sarcocyst wall had a mesh-like structure with irregularly shaped vp that were folded over the sarcocyst wall. On each vp there were uniform papillomatous structures that were 100 nm wide. By TEM, vp were up to 6 µm long and contained filamentous tubular structures, most of which were parallel to the long axis of the projections; granules were absent from these tubules. By TEM, bradyzoites within the same cyst varied from 11.2 to 16.8 µm in length. By TEM, bradyzoites had a very long (10 µm) convoluted mitochondrion, up to 12 dense granules, but only 2 rhoptries. This redescription should help to differentiate the sarcocysts of S. fusiformis from similar sarcocysts in domestic and wild ruminants.

Molecular characterization and development of Sarcocystis speeri sarcocysts in gamma interferon gene knockout mice.

The North American opossum (Didelphis virginiana) is the definitive host for at least three named species of Sarcocystis: Sarcocystis falcatula, Sarcocystis neurona and Sarcocystis speeri. The South American opossums (Didelphis albiventris, Didelphis marsupialis and Didelphis aurita) are definitive hosts for S. falcatula and S. lindsayi. The sporocysts of these Sarcocystis species are similar morphologically. They are also not easily distinguished genetically because of the difficulties of DNA extraction from sporocysts and availability of distinguishing genetic markers. Some of these species can be distinguished by bioassay; S. neurona and S. speeri are infective to gamma interferon gene knockout (KO) mice, but not to budgerigars (Melopsittacus undulatus); whereas S. falcatula and S. lindsayi are infective to budgerigars but not to KO mice. The natural intermediate host of S. speeri is unknown. In the present study, development of sarcocysts of S. speeri in the KO mice is described. Sarcocysts were first seen at 12 days post-inoculation (p.i.), and they became macroscopic (up to 4 mm long) by 25 days p.i. The structure of the sarcocyst wall did not change from the time bradyzoites had formed at 50-220 days p.i. Sarcocysts contained unique villar protrusions, 'type 38'. The polymerase chain reaction amplifications and sequences analysis of three nuclear loci (18S rRNA, 28S rRNA and ITS1) and two mitochondrial loci (cox1 and cytb) of S. speeri isolate from an Argentinean opossum (D. albiventris) confirmed its membership among species of Sarcocystis and indicated an especially close relationship to another parasite in this genus that employs opossums as its definitive host, S. neurona. These results should be useful in finding natural intermediate host of S. speeri.

TNF-α levels in HIV-infected patients after long-term suppressive cART persist as high as in elderly, HIV-uninfected subjects.

BACKGROUND: Chronic and systemic inflammatory alterations occur in HIV-infected patients and elderly uninfected subjects and in both scenarios these alterations are associated with the development of chronic morbidities and mortality. However, whether the levels of inflammatory alterations in untreated HIV-infected patients and elderly individuals are similar is unknown. Moreover, whether long-term antiretroviral therapy normalizes inflammatory alterations compared with HIV-uninfected persons of different age is not known. METHODS: We analysed soluble inflammatory levels [high-sensitivity C-reactive protein, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, IL-8 and IL-17] in a cohort of viraemic HIV-infected patients compared with (i) age-matched, (ii) elderly and (iii) non-survivor elderly, uninfected healthy controls. We longitudinally analysed the effect of long-term 48 and 96 week suppressive combined antiretroviral therapy (cART) on the soluble inflammatory levels compared with those found in control subjects. RESULTS: Baseline IL-6 and IL-8 levels were at similar or lower concentrations in untreated patients compared with healthy elderly individuals. However, TNF-α and IFN-γ levels broadly exceeded those found in survivors and non-survivor elderly individuals. Long-term suppressive cART normalized most of the inflammatory markers, with the exception of TNF-α levels, which persisted as high as those in elderly non-survivor controls. CONCLUSIONS: Chronic inflammatory alterations associated with HIV infection are maintained at a different level from those of ageing. The persistent alteration of TNF-α levels in HIV-infected patients might cause tissue damage and have implications for developing non-AIDS-defining illnesses, even when HIV replication is long-term controlled by cART.

MOLECULAR AND MORPHOLOGICAL CHARACTERIZATION OF SARCOCYSTIS INFECTIONS IN THE MUSCLES OF GRAY WOLVES (CANIS LUPUS) FROM MINNESOTA SUGGEST THEY MAY SERVE AS RESERVOIRS FOR INFECTION IN DOMESTICATED DOGS.

ABSTRACT: Sarcocystis infections were found for the first time in the muscles of 3 of 3 gray wolves (Canis lupus) from Minnesota. Two kinds (thin-walled and thick-walled) of sarcocysts were detected, based on the appearance of the sarcocyst wall. In wolf 1, sarcocysts were thin-walled (<0.5 µm), and without any visible protrusions. Ultrastructurally, the sarcocyst wall was type 1a and identical to Sarcocystis svanai of the domestic dog (Canis familiaris). The second kind of sarcocyst, with a relatively thicker (>1 µm) sarcocyst wall, was detected in wolves 2 and 3. Ultrastructurally, the sarcocyst wall had undulating, pleomorphic villar protrusion of type 9c; these sarcocysts were identical to Sarcocystis caninum from the domestic dog. Molecularly, the 2 Sarcocystis species were characterized using 18S, 28S, COI, ITS-1, and rpoB genetic markers. All these markers showed 100% identity to either of the 2 species previously described from the domestic dog. The thick-walled sarococyst corresponded to Sarcocystis caninum, whereas the thin-walled sarcocyst corresponded to Sarcocystis svanai.

Homogeneous ice nucleation at moderate supercooling from molecular simulation.

Among all of the freezing transitions, that of water into ice is probably the most relevant to biology, physics, geology, or atmospheric science. In this work, we investigate homogeneous ice nucleation by means of computer simulations. We evaluate the size of the critical cluster and the nucleation rate for temperatures ranging between 15 and 35 K below melting. We use the TIP4P/2005 and the TIP4P/ice water models. Both give similar results when compared at the same temperature difference with the model's melting temperature. The size of the critical cluster varies from ∼8000 molecules (radius = 4 nm) at 15 K below melting to ∼600 molecules (radius = 1.7 nm) at 35 K below melting. We use Classical Nucleation Theory (CNT) to estimate the ice-water interfacial free energy and the nucleation free-energy barrier. We obtain an interfacial free energy of 29(3) mN/m from an extrapolation of our results to the melting temperature. This value is in good agreement both with experimental measurements and with previous estimates from computer simulations of TIP4P-like models. Moreover, we obtain estimates of the nucleation rate from simulations of the critical cluster at the barrier top. The values we get for both models agree within statistical error with experimental measurements. At temperatures higher than 20 K below melting, we get nucleation rates slower than the appearance of a critical cluster in all water of the hydrosphere during the age of the universe. Therefore, our simulations predict that water freezing above this temperature must necessarily be heterogeneous.

Endothelial apoptosis in Braf-deficient mice.

Tyrosine kinase growth factor receptors and Ras/Raf/MEK/MAPK signalling have been implicated in the suppression as well as augmentation of programmed cell death. In addition, a Ras-independent role for Raf as a suppressor of programmed cell death has been suggested by the recent finding that Craf1 interacts with members of the Bcl-2 family at mitochondrial membranes. However, genetic studies of C. elegans and Drosophila, as well as the targeted mutagenesis of the murine Araf gene, have failed to support such a role. Here we show that mice with a targeted disruption in the Braf gene die of vascular defects during mid-gestation. Braf -/- embryos, unlike Araf -/- or Craf1 -/- embryos (L.W. et al., unpublished), show an increased number of endothelial precursor cells, dramatically enlarged blood vessels and apoptotic death of differentiated endothelial cells. These results establish Braf as a critical signalling factor in the formation of the vascular system and provide the first genetic evidence for an essential role of Raf gene in the regulation of programmed cell death.

Persistent luminescence dosimetry performance of solid state synthesized BaZrO3 phosphors.

This work reports for the first time on the thermoluminescence (TL) and persistent luminescence (PLu) characterization of BaZrO3 synthesized through solid state reaction. X-Ray diffraction confirmed the crystalline structure of the synthesized phosphors. The characteristic glow curves of the synthesized samples exhibit TL maxima located at 85 and 165 °C, whose fading after radiation exposure gives rise to intense PLu. PLu decay curves were recorded after beta particle irradiation in the dose range from 1.0 up to 1024 Gy. Both TL and PLu exhibit remarkable reproducibility. The integrated persistent luminescence (IPLu) as a function of the irradiation dose exhibits a linear dependence in the 1.0-16 Gy dose range, followed by a sublinear behavior from 16 to 128 Gy. From the experimental evidence here presented, it is concluded that solid state synthesized BaZrO3 is an interesting phosphor material to be implemented as a PLu-based detector and dosimeter.

Beta radiation excited thermoluminescence of solid-state synthesized SrZrO3 phosphors.

In this work, we report on the solid-state reaction synthesis of SrZrO3 phosphors, and their beta particle irradiation excited thermoluminescence (TL) characterization. X-ray diffraction data confirmed the obtention of the orthorhombic phase of SrZrO3. Through computational glow curve deconvolution, the whole glow curve was resolved into six individual first order kinetics peaks. This is the first report concerning the usefulness of SrZrO3 as TL dosimeter. The synthesized phosphors exhibit TL emission from below 100 °C up to above 300 °C, being the most intense TL between 200 and 300 °C, as well as a remarkable reproducibility of the TL response in repeated irradiation-TL readout cycles.

Elastic response and wrinkling onset of curved elastic membranes subjected to indentation test.

Starting from a polymeric-fluid droplet, by vulcanization of the fluid free surface, curved elastic membranes, several nanometers thick and a few millimeters in diameter, which enclose a constant fluid volume, are produced. In an indentation-type test, carried out by pushing the membrane along its normal by means of a micro-needle, under some conditions, wrinkles are likely to appear around the contact region. Interestingly, we observe that the instability does not significantly alter the force-displacement relation: the relation between the force and the displacement remains linear and the associated stiffness is simply proportional to the tension of the membrane. In addition, we determine that the wrinkles develop when the stretching modulus of the membrane compares with its tension, which provides a useful method to estimate the elastic constant.

Beta radiation excited thermoluminescence of SrB4O7 phosphors synthesized through solid state reaction.

In this work, the synthesis of SrB4O7 through solid state reaction and its beta particle excited thermoluminescence (TL) are reported. The glow curves show maxima around 200 and 300 -considered suitable for TL dosimetry-, and a remarkable reproducibility in successive irradiation - TL readout cycles. The integrated TL exhibits a linear dependence upon the irradiation dose in the tested dose range (from 1.0 up to 8.0 Gy). The lower detection limit and the sensitivity relative to the TLD-100 dosimeter are 88 mGy and 0.49, respectively. From the results here presented, we conclude that SrB4O7 synthesized through solid state reaction can be considered a phosphor material interesting to develop TL dosimeters.

Beta particle excited thermoluminescence of CaZrO3 phosphors synthesized by solid state reaction.

In this work, the synthesis through solid state reaction and the thermoluminescence (TL) characterization of pellet shaped CaZrO3 samples is reported. X-ray diffraction confirms that orthorhombic CaZrO3 was obtained. The glow curve has two maxima located at 149 and 216 °C as well as a less intense maximum around 350 °C when a 5.0 °C/s heating rate is used after 64 Gy of beta particle exposure. A remarkably reproducibility of the TL response is observed in repeated irradiation - TL readouts cycles. The TL as a function of the dose displays linear dependence in the dose range from 0.5 to 256 Gy. The intensity of the maximum located around 216 °C remains 61% 14 days after irradiation, and then remains closely constant for longer times. The synthesized CaZrO3 exhibits TL properties potentially of interest for use in radiation detection and dosimetry.