Accessing the soot-related radiative heat feedback in a flame spreading in microgravity: optical designs and associated limitations

Novel, high-fidelity results related to soot from microgravity flames were obtained by an international topical team on fire safety in space. More specifically, embedded optical techniques for evaluation of the soot-related radiative feedback to the base material from a spreading non-premixed flame in microgravity were developed. The configuration used a non-buoyant axisymmetric flame propagating in an opposed laminar stream overa Low Density PolyEthylene coating of an electrical wire. Within this context, both the standard Broadband Two Color Pyrometry (B2CP) and its recent extension Broadband Modulated Absorption/Emission (BMAE) technique can be deployed to measure the spatial distribution of soot temperature and volume fraction within the flame. Both fields are then processed to establish the field of local radiative balance attributed to soot within the flame, and ultimately the soot contribution to the radiative flux to the wire. The present study first assesses the consistency of the methodology contrasting an experimental frame and a synthetic one, the latter being produced by a signal modeling that processes fields delivered by a numerical simulation of the configuration as inputs. Using the synthetic signals obtained, the fields of local radiative balance within the flame are then computed and significant discrepancies were disclosed locally between the fields originating from the synthetic BMAE and B2CP inputs. Nevertheless, the subsequent evaluation of the soot-related radiative heat feedback to the wire shows that a weak deviation among the techniques implemented is expected. This finding is corroborated by similar evaluations conducted with experimental BMAE and B2CP measurements obtained in parabolic flights. As BMAE is implemented in an ISS configuration within the SCEM rig, BMAE and B2CP will soon provide long-duration soot observations in microgravity. In order to contrast the upcoming results, this current study quantifies discrepancies originating from the post-processing regarding soot temperature and volume fraction, and shows that the radiative feedback evaluation from both methods should be consistent

Accessing the soot-related radiative heat feedback in a flame spreading in microgravity: Optical designs and associated limitations

Novel, high-fidelity results related to soot from microgravity flames were obtained by an international topical team on fire safety in space. More specifically, embedded optical techniques for evaluation of the soot-related radiative feedback to the base material from a spreading non-premixed flame in microgravity were developed. The configuration used a non-buoyant axisymmetric flame propagating in an opposed laminar stream over a Low Density PolyEthylene coating of an electrical wire. Within this context, both the standard Broadband Two Color Pyrometry (B2CP) and its recent extension Broadband Modulated Absorption/Emission (BMAE) technique can be deployed to measure the spatial distribution of soot temperature and volume fraction within the flame. Both fields are then processed to establish the field of local radiative balance attributed to soot within the flame, and ultimately the soot contribution to the radiative flux to the wire. The present study first assesses the consistency of the methodology contrasting an experimental frame and a synthetic one, the latter being produced by a signal modeling that processes fields delivered by a numerical simulation of the configuration as inputs. Using the synthetic signals obtained, the fields of local radiative balance within the flame are then computed and significant discrepancies were disclosed locally between the fields originating from the synthetic BMAE and B2CP inputs. Nevertheless, the subsequent evaluation of the soot-related radiative heat feedback to the wire shows that a weak deviation among the techniques implemented is expected. This finding is corroborated by similar evaluations conducted with experimental BMAE and B2CP measurements obtained in parabolic flights. As BMAE is implemented in an ISS configuration within the SCEM rig, BMAE and B2CP will soon provide long-duration soot observations in microgravity. In order to contrast the upcoming results, this current study quantifies discrepancies originating from the post-processing regarding soot temperature and volume fraction, and shows that the radiative feedback evaluation from both methods should be consistent

Bacterial Deposition of Gold on Hair: Archeological, Forensic and Toxicological Implications

Trace metal analyses in hair are used in archeological, forensic and toxicological investigations as proxies for metabolic processes. We show metallophilic bacteria mediating the deposition of gold (Au), used as tracer for microbial activity in hair post mortem after burial, affecting results of such analyses. Methodology/Principal Findings Human hair was incubated for up to six months in auriferous soils, in natural soil columns (Experiment 1), soils amended with mobile Au(III)-complexes (Experiment 2) and the Au-precipitating bacterium Cupriavidus metallidurans (Experiment 3), in peptone-meat-extract (PME) medium in a culture of C. metallidurans amended with Au(III)-complexes (Experiment 4), and in non-auriferous soil (Experiment 5). Hair samples were analyzed using scanning electron microscopy, confocal microscopy and inductively coupled plasma-mass spectrometry. In Experiments 1–4 the Au content increased with time (P = 0.038). The largest increase was observed in Experiment 4 vs. Experiment 1 (mean = 1188 vs. 161 µg Kg−1, Fisher's least significance 0.001). The sulfur content, a proxy for hair metabolism, remained unchanged. Notably, the ratios of Au-to-S increased with time (linear trend P = 0.02) and with added Au and bacteria (linear trend, P = 0.005), demonstrating that larger populations of Au-precipitating bacteria and increased availability of Au increased the deposition of Au on the hair. Conclusion/Significance Interactions of soil biota with hair post mortem may distort results of hair analyses, implying that metal content, microbial activities and the duration of burial must be considered in the interpretation of results of archeological, forensic and toxicological hair analyses, which have hitherto been proxies for pre-mortem metabolic processesGenevieve Phillips, Frank Reith, Clifford Qualls, Abdul-Mehdi Ali, Mike Spilde and Otto Appenzelle

Population Carrier Rates of Pathogenic ARSA Gene Mutations: Is Metachromatic Leukodystrophy Underdiagnosed?

BACKGROUND: Metachromatic leukodystrophy (MLD) is a severe neurometabolic disease caused mainly by deficiency of arylsulfatase A encoded by the ARSA gene. Based on epidemiological surveys the incidence of MLD per 100,000 live births varied from 0.6 to 2.5. Our purpose was to estimate the birth prevalence of MLD in Poland by determining population frequency of the common pathogenic ARSA gene mutations and to compare this estimate with epidemiological data. METHODOLOGY: We studied two independently ascertained cohorts from the Polish background population (N∼3000 each) and determined carrier rates of common ARSA gene mutations: c.459+1G>A, p.P426L, p.I179S (cohort 1) and c.459+1G>A, p.I179S (cohort 2). PRINCIPAL FINDINGS: Taking into account ARSA gene mutation distribution among 60 Polish patients, the expected MLD birth prevalence in the general population (assuming no selection against homozygous fetuses) was estimated as 4.0/100,000 and 4.1/100,000, respectively for the 1(st) and the 2(nd) cohort with a pooled estimate of 4.1/100,000 (CI: 1.8-9.4) which was higher than the estimate of 0.38 per 100,000 live births based on diagnosed cases. The p.I179S mutation was relatively more prevalent among controls than patients (OR = 3.6, P = 0.0082, for a comparison of p.I179S frequency relative to c.459+1G>A between controls vs. patients). CONCLUSIONS/SIGNIFICANCE: The observed discrepancy between the measured incidence of metachromatic leukodystrophy and the predicted carriage rates suggests that MLD is substantially underdiagnosed in the Polish population. The underdiagnosis rate may be particularly high among patients with p.I179S mutation whose disease is characterized mainly by psychotic symptoms

Clinical spectrum of MTOR-related hypomelanosis of Ito with neurodevelopmental abnormalities

PURPOSE: Hypomelanosis of Ito (HI) is a skin marker of somatic mosaicism. Mosaic MTOR pathogenic variants have been reported in HI with brain overgrowth. We sought to delineate further the pigmentary skin phenotype and clinical spectrum of neurodevelopmental manifestations of MTOR-related HI. METHODS: From two cohorts totaling 71 patients with pigmentary mosaicism, we identified 14 patients with Blaschko-linear and one with flag-like pigmentation abnormalities, psychomotor impairment or seizures, and a postzygotic MTOR variant in skin. Patient records, including brain magnetic resonance image (MRI) were reviewed. Immunostaining (n = 3) for melanocyte markers and ultrastructural studies (n = 2) were performed on skin biopsies. RESULTS: MTOR variants were present in skin, but absent from blood in half of cases. In a patient (p.[Glu2419Lys] variant), phosphorylation of p70S6K was constitutively increased. In hypopigmented skin of two patients, we found a decrease in stage 4 melanosomes in melanocytes and keratinocytes. Most patients (80%) had macrocephaly or (hemi)megalencephaly on MRI. CONCLUSION: MTOR-related HI is a recognizable neurocutaneous phenotype of patterned dyspigmentation, epilepsy, intellectual deficiency, and brain overgrowth, and a distinct subtype of hypomelanosis related to somatic mosaicism. Hypopigmentation may be due to a defect in melanogenesis, through mTORC1 activation, similar to hypochromic patches in tuberous sclerosis complex

Phosphofructo-1-Kinase Deficiency Leads to a Severe Cardiac and Hematological Disorder in Addition to Skeletal Muscle Glycogenosis

Mutations in the gene for muscle phosphofructo-1-kinase (PFKM), a key regulatory enzyme of glycolysis, cause Type VII glycogen storage disease (GSDVII). Clinical manifestations of the disease span from the severe infantile form, leading to death during childhood, to the classical form, which presents mainly with exercise intolerance. PFKM deficiency is considered as a skeletal muscle glycogenosis, but the relative contribution of altered glucose metabolism in other tissues to the pathogenesis of the disease is not fully understood. To elucidate this issue, we have generated mice deficient for PFKM (Pfkm−/−). Here, we show that Pfkm−/− mice had high lethality around weaning and reduced lifespan, because of the metabolic alterations. In skeletal muscle, including respiratory muscles, the lack of PFK activity blocked glycolysis and resulted in considerable glycogen storage and low ATP content. Although erythrocytes of Pfkm−/− mice preserved 50% of PFK activity, they showed strong reduction of 2,3-biphosphoglycerate concentrations and hemolysis, which was associated with compensatory reticulocytosis and splenomegaly. As a consequence of these haematological alterations, and of reduced PFK activity in the heart, Pfkm−/− mice developed cardiac hypertrophy with age. Taken together, these alterations resulted in muscle hypoxia and hypervascularization, impaired oxidative metabolism, fiber necrosis, and exercise intolerance. These results indicate that, in GSDVII, marked alterations in muscle bioenergetics and erythrocyte metabolism interact to produce a complex systemic disorder. Therefore, GSDVII is not simply a muscle glycogenosis, and Pfkm−/− mice constitute a unique model of GSDVII which may be useful for the design and assessment of new therapies

MRCP compared to diagnostic ERCP for diagnosis when biliary obstruction is suspected: a systematic review

BACKGROUND: Magnetic resonance cholangiopancreatography (MRCP) is an alternative to diagnostic endoscopic retrograde cholangiopancreatography (ERCP) for investigating biliary obstruction. The use of MRCP, a non-invasive procedure, may prevent the use of unnecessary invasive procedures. The aim of the study was to compare the findings of MRCP with those of ERCP by the computation of accuracy statistics. METHODS: Thirteen electronic bibliographic databases, covering biomedical, science, health economics and grey literature were searched. A systematic review of studies comparing MRCP to diagnostic ERCP in patients with suspected biliary obstruction was conducted. Sensitivity, specificity, likelihood ratios, acceptability and adverse events were reported. RESULTS: 25 studies were identified reporting several conditions including choledocholithiasis (18 studies), malignancy (four studies), obstruction (three studies), stricture (two studies) and dilatation (five studies). Three of the 18 studies reporting choledocholithiasis were excluded from the analysis due to lack of data, or differences in study design. The sensitivity for the 15 studies of choledocholithiasis ranged from 0.50 to 1.00 while specificity ranged from 0.83 to 1.00. The positive likelihood ratio ranged: from 5.44–47.72 and the negative likelihood ratio for the 15 studies ranged from 0.00–0.51. Significant heterogeneity was found across the 15 studies so the sensitivities and specificities were summarised by a Receiver Operating Characteristic (ROC) curve. For malignancy, sensitivity ranged from 0.81 to 0.94 and specificity from 0.92 to 1.00. Positive likelihood ratios ranged from 10.12 to 43 and negative likelihood ratios ranged from 0.15 to 0.21, although these estimates were less reliable. CONCLUSION: MRCP is a comparable diagnostic investigation in comparison to ERCP for diagnosing biliary obstruction

Influence of metals and metalloids on the composition and fluorescence quenching of the extracellular polymeric substances produced by the polymorphic fungus <i>Aureobasidium pullulans</i>

Aureobasidium pullulansis a ubiquitous and widely distributed fungus in the environment, and exhibits substantial tolerance against toxic metals. However, the interactions between metals and metalloids with the copious extracellular polymeric substances (EPS) produced byA. pullulansand possible relationships to tolerance are not well understood. In this study, it was found that mercury (Hg) and selenium (Se), as selenite, not only significantly inhibited growth ofA. pullulansbut also affected the composition of produced EPS. Lead (Pb) showed little influence on EPS yield or composition. The interactions of EPS fromA. pullulanswith the tested metals and metalloids depended on the specific element and their concentration. Fluorescence intensity measurements of the EPS showed that the presence of metal(loid)s stimulated the production of extracellular tryptophan-like and aromatic protein-like substances. Examination of fluorescence quenching and calculation of binding constants revealed that the fluorescence quenching process for Hg; arsenic (As), as arsenite; and Pb to EPS were mainly governed by static quenching which resulted in the formation of a stable non-fluorescent complexes between the EPS and metal(loid)s. Se showed no significant interaction with the EPS according to fluorescence quenching. These results provide further understanding of the interactions between metals and metalloids and EPS produced by fungi and their contribution to metal(loid) tolerance