Science.gov

Sample records for properties influence calcification

  1. Determining the influence of calcification on the failure properties of abdominal aortic aneurysm (AAA) tissue.

    PubMed

    O'Leary, Siobhan A; Mulvihill, John J; Barrett, Hilary E; Kavanagh, Eamon G; Walsh, Michael T; McGloughlin, Tim M; Doyle, Barry J

    2015-02-01

    Varying degrees of calcification are present in most abdominal aortic aneurysms (AAAs). However, their impact on AAA failure properties and AAA rupture risk is unclear. The aim of this work is evaluate and compare the failure properties of partially calcified and predominantly fibrous AAA tissue and investigate the potential reasons for failure. Uniaxial mechanical testing was performed on AAA samples harvested from 31 patients undergoing open surgical repair. Individual tensile samples were divided into two groups: fibrous (n=31) and partially calcified (n=38). The presence of calcification was confirmed by fourier transform infrared spectroscopy (FTIR). A total of 69 mechanical tests were performed and the failure stretch (λf), failure stress (σf) and failure tension (Tf) were recorded for each test. Following mechanical testing, the failure sites of a subset of both tissue types were examined using scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) to investigate the potential reasons for failure. It has been shown that the failure properties of partially calcified tissue are significantly reduced compared to fibrous tissue and SEM and EDS results suggest that the junction between a calcification deposit and the fibrous matrix is highly susceptible to failure. This study implicates the presence of calcification as a key player in AAA rupture risk and provides further motivation for the development of non-invasive methods of measuring calcification.

  2. Local influence of calcifications on the wall mechanics of abdominal aortic aneurysm

    NASA Astrophysics Data System (ADS)

    de Putter, Sander; van de Vosse, Frans N.; Breeuwer, Marcel; Gerritsen, Frans A.

    2006-03-01

    Finite element wall stress simulations on patient-specific models of abdominal aortic aneurysm (AAA) may provide a better rupture risk predictor than the currently used maximum transverse diameter. Calcifications in the wall of AAA lead to a higher maximum wall stress and thus may lead to an elevated rupture risk. The reported material properties for calcifications and the material properties actually used for simulations show great variation. Previous studies have focused on simplified modelling of the calcification shapes within a realistic aneurysm shape. In this study we use an accurate representation of the calcification geometry and a simplified model for the AAA. The objective of this approach is to investigate the influence of the calcification geometry, the material properties and the modelling approach for the computed peak wall stress. For four realistic calcification shapes from standard clinical CT images of AAA, we performed simulations with three distinct modelling approaches, at five distinct elasticity settings. The results show how peak wall stress is sensitive to the material properties of the calcifications. For relatively elastic calcifications, the results from the different modelling approaches agree. Also, for relatively elastic calcifications the computed wall stress in the tissue surrounding the calcifications shows to be insensitive to the exact calcification geometry. For stiffer calcifications the different modelling approaches and the different geometries lead to significantly different results. We conclude that an important challenge for future research is accurately estimating the material properties and the rupture potential of the AAA wall including calcifications.

  3. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Mackenzie, A.; Dance, D. R.; Young, K. C.

    2013-04-01

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  4. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate.

    PubMed

    Warren, L M; Mackenzie, A; Dance, D R; Young, K C

    2013-04-07

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  5. Fixation of vascular grafts with increased glutaraldehyde concentration enhances mechanical properties without increasing calcification.

    PubMed

    Sánchez, Diana M; Gaitán, Diana M; León, Andrés F; Mugnier, Jacqueline; Briceño, Juan C

    2007-01-01

    Our objective was to study the effect of glutaraldehyde (GLU) concentration, heat, and photooxidation on mechanical properties and calcification of bovine pericardium grafts in an in vivo model. Fresh pericardia were treated as follows: 0.625% GLU for 7 days (standard); 0.625%, 1%, and 3% GLU at 4 degrees C for 20 days and 50 degrees C for additional 20 days; irradiation in cross-linking medium with metilene blue at 0 degrees C for 8 hours. Tissues were subjected to tensile mechanical tests (n = 76). Fixed patches were subcutaneously implanted in mice for 50 days (n = 16 per treatment). Calcification was assessed by atomic absorption spectrophotometry (n = 55) and von Kossa staining (n = 28). Analysis of variance and Tukey's test were used for statistical analysis. The 3% GLU and 3% GLU + heat treatments showed an enhancement of the mechanical properties above standard treatment. No significant difference was found in calcification between treatments. The 3% GLU treatment enhances the mechanical properties of the tissue above standard treatment without increasing calcification and without applying heat; therefore it is recommended for high-strength applications. Supplementary treatments to decrease calcification could be combined with this methodology to obtain a high-strength-low-calcification biomaterial for manufacturing of long-term cardiovascular grafts.

  6. Influence of Land Development on Holocene Porites Coral Calcification at Nagura Bay, Ishigaki Island, Japan

    PubMed Central

    Sowa, Kohki; Watanabe, Tsuyoshi; Kan, Hironobu; Yamano, Hiroya

    2014-01-01

    To evaluate the relationships between coral calcification, thermal stress, and sedimentation and eutrophication linked to human impact (hereafter referred to as “land development”) by river discharge, we analyzed growth characteristics in the context of a paleoenvironment that was reconstructed from geochemical signals in modern and fossil (1.2 cal kyr BP and 3.5 cal kyr BP, respectively) massive Porites corals from Nagura Bay (“Nagura”) and from modern Porites corals from the estuary of the Todoroki River, Shiraho Reef (“Todoroki”). Both sites are on Ishigaki Island, Japan, and Nagura is located approximately 12 km west of Todoroki. At Nagura, the individual corals provide time windows of 13 (modern), 10 (1.2 cal kyr BP), and 38 yr in length (3.5 cal kyr BP). Here, we present the coral annual calcification for Nagura and Todoroki, and (bi) monthly resolved records of Sr/Ca (a proxy of sea surface temperature (SST)) and Ba/Ca (a proxy of sedimentation and nutrients related to land development) for Nagura. At Nagura, the winter SST was cooler by 2.8°C in the 1.2 cal kyr BP, and the annual and winter SSTs in the 3.5 cal kyr BP were cooler by 2.6°C and 4.6°C, respectively. The annual periodicity of Ba/Ca in modern coral is linked to river discharge and is associated with land development including sugar cane cultivation. Modern coral calcification also has declined with SST warming and increasing Ba/Ca peaks in winter. However, calcification of fossil corals does not appear to have been influenced by variations in Sr/Ca and Ba/Ca. Modern coral growth characteristics at Nagura and Todoroki indicate that coral growth is both spatially and temporally influenced by river discharge and land development. At Nagura, our findings suggest that land development induces negative thermal sensitivity for calcification in winter due to sugar cane harvest, which is a specifically modern phenomenon. PMID:24586393

  7. Calcification rate influence on trace element concentrations in aragonitic bivalve shells: Evidences and mechanisms

    NASA Astrophysics Data System (ADS)

    Carré, Matthieu; Bentaleb, Ilhem; Bruguier, Olivier; Ordinola, Elmer; Barrett, Nicholas T.; Fontugne, Michel

    2006-10-01

    Trace elements in calcareous organisms have been widely used for paleoclimatic studies. However, the factors controlling their incorporation into mollusc shells are still unclear. We studied here the Sr, Mg, Ba and Mn serial records in the shells of two aragonitic marine bivalve species: Mesodesma donacium and Chione subrugosa from the Peruvian Coast. The elemental concentrations were compared to local temperature and salinity records. The relationships with crystal growth rate G were investigated thanks to well defined periodic growth structures providing a precise shell chronology. Our results show that for both species, environmental parameters only have minor influence, whereas crystal growth rate strongly influences trace elements concentrations, especially for Sr (explaining up to 74% of the variance). The relationship between G and Sr/Ca exhibits variability among the shells as well as inside the shells. For a same growth rate value, Sr/Ca values are higher in more curved shell sections, and the growth rate influence is stronger as well. We show that intercellular and Ca 2+-pump pathways cannot support the calcification Ca 2+ flux, leading us to propose an alternative mechanism for ionic transport through the calcifying mantle, implying a major role for calcium channels on mantle epithelial cell membranes. In this new calcification model, Sr/Ca shell ratios is determined by Ca 2+-channel selectivity against Sr 2+, which depends (i) on the electrochemical potential imposed by the crystallisation process and (ii) on the Ca 2+-channel density per surface unit on mantle epithelia.

  8. Influences of organic matter and calcification rate on trace elements in aragonitic estuarine bivalve shells

    USGS Publications Warehouse

    Takesue, R.K.; Bacon, C.R.; Thompson, J.K.

    2008-01-01

    ., Bruguier O., Ordinola E., Barrett N. T. and Fontugne M. (2006) Calcification rate influence on trace element concentrations in aragonitic bivalve shells: evidences and mechanisms. Geochim. Cosmochim. Acta 70, 4906-4920] which predicts that [M]/Ca ratios increase as calcification rates increase and Ca2+ channel specificity decreases. This result, in combination with the possibility that there were ontogenetic variations in growth rates among individuals younger than 2 years, underscores the need to develop an independent age model for C. amurensis shells. If growth-rate effects on lattice-bound [M]/Ca ratios can be constrained, it may yet be possible to develop high-resolution geochemical proxies for external solution chemistry in low-salinity regions of SFB.

  9. Influence of plaque calcifications on coronary stent fracture: a numerical fatigue life analysis including cardiac wall movement.

    PubMed

    Morlacchi, Stefano; Pennati, Giancarlo; Petrini, Lorenza; Dubini, Gabriele; Migliavacca, Francesco

    2014-03-03

    Coronary stent fracture is still an unresolved issue in the field of minimally invasive cardiovascular interventions due to its high rate of incidence and uncertain clinical consequences. Recent studies, based on clinical data, proved that there are several factors which can be identified as independently responsible of coronary stent fracture. Among these, calcifications, which increase the local stiffness and heterogeneity of atherosclerotic plaques, seem to play a major role. From a mechanical point of view, stent fracture in coronary arteries is triggered by the cyclic loading of pulsatile blood pressure combined with the movement of cardiac wall. In this context, this study aims at simulating the stent expansion in a model of epicardial atherosclerotic coronary artery and correlating the effects of cyclic blood pressure and cardiac wall movement on the stent fatigue resistance. Two ideal cases of atherosclerotic plaques were modelled: the first one included a localised plaque calcification; the latter one did not include such calcification. Results of stress/strain and fatigue analyses confirmed the influence of the plaque calcification on potential fracture of the devices. In addition, the effects of cardiac wall movement were quantified as more dangerous causes of the stent fatigue fracture with respect to the internal blood pressure oscillations. In conclusion, this study demonstrates the increased risk of coronary stent fracture associated to the presence of localised plaque calcifications. This work also suggests the necessity of more realistic biomechanical models which takes into account the heterogeneity of atherosclerotic plaques in order to assess the mechanical performances of coronary stents.

  10. Arterial calcifications

    PubMed Central

    Rennenberg, Roger J M W; Schurgers, Leon J; Kroon, Abraham A; Stehouwer, Coen D A

    2010-01-01

    Abstract Arterial calcifications as found with various imaging techniques, like plain X-ray, computed tomography or ultrasound are associated with increased cardiovascular risk. The prevalence of arterial calcification increases with age and is stimulated by several common cardiovascular risk factors. In this review, the clinical importance of arterial calcification and the currently known proteins involved are discussed. Arterial calcification is the result of a complex interplay between stimulating (bone morphogenetic protein type 2 [BMP-2], RANKL) and inhibitory (matrix Gla protein, BMP-7, osteoprotegerin, fetuin-A, osteopontin) proteins. Vascular calcification is especially prevalent and related to adverse outcome in patients with renal insufficiency and diabetes mellitus. We address the special circumstances and mechanisms in these patient groups. Treatment and prevention of arterial calcification is possible by the use of specific drugs. However, it remains to be proven that reduction of vascular calcification in itself leads to a reduced cardiovascular risk. PMID:20716128

  11. Influence of Eunice norvegica on feeding and calcification in the coral Lophelia pertusa

    NASA Astrophysics Data System (ADS)

    Mueller, C. E.; van Oevelen, D.; Middelburg, J. J.; Lundälv, T.

    2012-04-01

    Lophelia pertusa is the main framework building cold-water coral in the North Atlantic. It forms complex reef structures, extending up to several km in length and several meters in hight. Many species are attracted by the coral frame work, forming a highly diverse community within the reef. Although most work has focused on the corals, the functioning of the system also depends on interactions between corals and associated species. A particular example is the Polychaete Eunice norvegica that lives in close association with the coral host. The Polychaete builds a thin texture-tube between living coral branches and stimulates the coral to calcify the tube. This process strengthens the reef framwork by thickening and connecting coral brances and thereby acts as a positive feedback on the development of large reef structures. This comes however at an metabolic cost for the coral due to the enhanced calcificationrates. Another negative feedback for cold-water coral may be food related, since aquaria observations have shown that Eunice occasionally steels food from its host coral. In this study we investigated the interactions between the coral and polychaete related to calcification and food partitioning for two food types (algae and Artemia). The uptake of 13C and 15N labeled food sources by the worm and the coral was studied in chambers with only corals, only the polychaete and both species present. After 7 days, corals and worms were analyzed for isotope incorporation in bulk tissue and skeleton samples and specific fatty acids (13C) using GC-c-IRMS (gas-chromatography-combustion-isotope ratio mass spectrometry). Corals that were kept in the presence of Eunice indeed showed a higher calcification rates of 7.4 ug C (day* g dw coral)-1, evidencing the stimulation of calcification by Eunice. Interestingly, food uptake of algae and Artemia was higher in the coral-worm treatment for both species as compared to the single species treatments. These results shed new light on

  12. Lanthanum chloride bidirectionally influences calcification in bovine vascular smooth muscle cells.

    PubMed

    Zhao, Wen-Hua; Gou, Bao-Di; Zhang, Tian-Lan; Wang, Kui

    2012-05-01

    Vascular calcification (VC) is frequent prevalence in patients with chronic kidney disease (CKD) and atherosclerosis. Lanthanum carbonate is used as an orally administered phosphate-binding agent to reduce the gastrointestinal absorption of phosphate and ameliorate VC in advanced CKD. In this study, we used bovine vascular smooth muscle cells as a model VC in vitro and studied the effects of lanthanum chloride on calcium deposition. Exposure of cells to LaCl(3) at the concentration of 0.1 µM suppressed the β-glycerophosphate-induced alkaline phosphatase activity and calcium deposition. Furthermore, LaCl(3) upregulated the β-glycerophosphate-suppressed expression of calcium-sensing receptor. In contrast to the inhibitory effect of LaCl(3) on calcium deposition, higher level lanthanum (50 µM) was found to promote immediately precipitation of calcium phosphate in cell culture medium. At this concentration, LaCl(3) was found to induce cell apoptosis which involves caspases-9 and -3. These data indicate that the promotory effect of LaCl(3) on calcium deposition is likely mediated by induction of apoptosis. Our in vitro findings do suggest that, in the context of raised lanthanum, greater attention should be paid to potential toxic effects associated to the use of lanthanide-based drugs.

  13. Influence of silk-silica fusion protein design on silica condensation in vitro and cellular calcification

    PubMed Central

    Plowright, Robyn; Dinjaski, Nina; Zhou, Shun; Belton, David J.; Kaplan, David L.; Perry, Carole C.

    2016-01-01

    Biomaterial design via genetic engineering can be utilized for the rational functionalization of proteins to promote biomaterial integration and tissue regeneration. Spider silk has been extensively studied for its biocompatibility, biodegradability and extraordinary material properties. As a protein-based biomaterial, recombinant DNA derived derivatives of spider silks have been modified with biomineralization domains which lead to silica deposition and potentially accelerated bone regeneration. However, the influence of the location of the R5 (SSKKSGSYSGSKGSKRRIL) silicifying domain fused with the spider silk protein sequence on the biosilicification process remains to be determined. Here we designed two silk-R5 fusion proteins that differed in the location of the R5 peptide, C- vs. N-terminus, where the spider silk domain consisted of a 15mer repeat of a 33 amino acid consensus sequence of the major ampullate dragline Spidroin 1 from Nephila clavipes (SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQGT). The chemical, physical and silica deposition properties of these recombinant proteins were assessed and compared to a silk 15mer control without the R5 present. The location of the R5 peptide did not have a significant effect on wettability and surface energies, while the C-terminal location of the R5 promoted more controlled silica precipitation, suggesting differences in protein folding and possibly different access to charged amino acids that drive the silicification process. Further, cell compatibility in vitro, as well as the ability to promote human bone marrow derived mesenchymal stem cell (hMSC) differentiation were demonstrated for both variants of the fusion proteins. PMID:26989487

  14. On the effect of calcification volume and configuration on the mechanical behaviour of carotid plaque tissue.

    PubMed

    Barrett, H E; Cunnane, E M; Kavanagh, E G; Walsh, M T

    2016-03-01

    Vascular calcification is a complex molecular process that exhibits a number of relatively characteristic morphology patterns in atherosclerotic plaques. Treatment of arterial stenosis by endovascular intervention, involving forceful circumferential expansion of the plaque, can be unpredictable in calcified lesions. The aim of this study was to determine the mechanical stretching mechanisms and define the mechanical limits for circumferentially expanding carotid plaque lesions under the influence of distinct calcification patterns. Mechanical and structural characterisation was performed on 17 human carotid plaques acquired from patients undergoing endarterectomy procedures. The mechanical properties were determined using uniaxial extension tests that stretch the lesions to complete failure along their circumferential axis. Calcification morphology of mechanically ruptured plaque lesions was characterised using high resolution micro computed tomography imaging. Scanning electron microscopy was used to examine the mechanically induced failure sites and to identify the interface boundary conditions between calcified and non-calcified tissue. The mechanical tests produced four distinct trends in mechanical behaviour which corresponded to the calcification patterns that structurally defined each mechanical group. Each calcification pattern produced unique mechanical restraining effects on the plaque tissue stretching properties evidenced by the variation in degree of stretch to failure. Resistance to failure appears to rely on interactions between calcification and non-calcified tissue. Scanning electron microscopy examination revealed structural gradations at interface boundary conditions to facilitate the transfer of stress. This study emphasises the mechanical influence of distinct calcification configurations on plaque expansion properties and highlights the importance of pre-operative lesion characterisation to optimise treatment outcomes.

  15. Calcification of the planktonic foraminifera Globigerina bulloides and carbonate ion concentration: Results from the Santa Barbara Basin

    NASA Astrophysics Data System (ADS)

    Osborne, Emily B.; Thunell, Robert C.; Marshall, Brittney J.; Holm, Jessica A.; Tappa, Eric J.; Benitez-Nelson, Claudia; Cai, Wei-Jun; Chen, Baoshan

    2016-08-01

    Planktonic foraminiferal calcification intensity, reflected by shell wall thickness, has been hypothesized to covary with the carbonate chemistry of seawater. Here we use both sediment trap and box core samples from the Santa Barbara Basin to evaluate the relationship between the calcification intensity of the planktonic foraminifera species Globigerina bulloides, measured by area density (µg/µm2), and the carbonate ion concentration of seawater ([CO32-]). We also evaluate the influence of both temperature and nutrient concentration ([PO43-]) on foraminiferal calcification and growth. The presence of two G. bulloides morphospecies with systematically different calcification properties and offset stable isotopic compositions was identified within sampling populations using distinguishing morphometric characteristics. The calcification temperature and by extension calcification depth of the more abundant "normal" G. bulloides morphospecies was determined using δ18O temperature estimates. Calcification depths vary seasonally with upwelling and were used to select the appropriate [CO32-], temperature, and [PO43-] depth measurements for comparison with area density. Seasonal upwelling in the study region also results in collinearity between independent variables complicating a straightforward statistical analysis. To address this issue, we use additional statistical diagnostics and a down core record to disentangle the respective roles of each parameter on G. bulloides calcification. Our results indicate that [CO32-] is the primary variable controlling calcification intensity while temperature influences shell size. We report a modern calibration for the normal G. bulloides morphospecies that can be used in down core studies of well-preserved sediments to estimate past [CO32-].

  16. [THE CHANGES IN THE STRUCTURAL REMODELING OF THE CAROTID ARTERY IN PATIENTS WITH HYPERTENSION AND HEART VALVE CALCIFICATION UNDER THE INFLUENCE OF TREATMENT].

    PubMed

    Yuzvishina, O V

    2014-01-01

    In patients with essential hypertension (EH) and heart valves calcification (HVC) were studied the dynamics of the structural remodeling of the carotid artery under the influence of different variants of lipid-lowering therapy. Significant decrease in the thickness of the intimamedia, the frequency of new atherosclerotic plaques have been seen in patients with EH and HVC using high-dose atorvastatin compared with less.

  17. Ultrastructural Analysis of Vascular Calcifications in Uremia

    PubMed Central

    Aretz, Anke; Verberckmoes, Steven C.; Krüger, Thilo; Behets, Geert J.; Ghadimi, Reza; Weirich, Thomas E.; Rohrmann, Dorothea; Langer, Stephan; Tordoir, Jan H.; Amann, Kerstin; Westenfeld, Ralf; Brandenburg, Vincent M.; D'Haese, Patrick C.; Mayer, Joachim; Ketteler, Markus; McKee, Marc D.; Floege, Jürgen

    2010-01-01

    Accelerated intimal and medial calcification and sclerosis accompany the increased cardiovascular mortality of dialysis patients, but the pathomechanisms initiating microcalcifications of the media are largely unknown. In this study, we systematically investigated the ultrastructural properties of medial calcifications from patients with uremia. We collected iliac artery segments from 30 dialysis patients before kidney transplantation and studied them by radiography, microcomputed tomography, light microscopy, and transmission electron microscopy including electron energy loss spectrometry, energy dispersive spectroscopy, and electron diffraction. In addition, we performed synchrotron x-ray analyses and immunogold labeling to detect inhibitors of calcification. Von Kossa staining revealed calcification of 53% of the arteries. The diameter of these microcalcifications ranged from 20 to 500 nm, with a core-shell structure consisting of up to three layers (subshells). Many of the calcifications consisted of 2- to 10-nm nanocrystals and showed a hydroxyapatite and whitlockite crystalline structure and mineral phase. Immunogold labeling of calcification foci revealed the calcification inhibitors fetuin-A, osteopontin, and matrix gla protein. These observations suggest that uremic microcalcifications originate from nanocrystals, are chemically diverse, and intimately associate with proteinaceous inhibitors of calcification. Furthermore, considering the core-shell structure of the calcifications, apoptotic bodies or matrix vesicles may serve as a calcification nidus. PMID:20203159

  18. Shellfish Face Uncertain Future in High CO2 World: Influence of Acidification on Oyster Larvae Calcification and Growth in Estuaries

    PubMed Central

    Miller, A. Whitman; Reynolds, Amanda C.; Sobrino, Cristina; Riedel, Gerhardt F.

    2009-01-01

    Background Human activities have increased atmospheric concentrations of carbon dioxide by 36% during the past 200 years. One third of all anthropogenic CO2 has been absorbed by the oceans, reducing pH by about 0.1 of a unit and significantly altering their carbonate chemistry. There is widespread concern that these changes are altering marine habitats severely, but little or no attention has been given to the biota of estuarine and coastal settings, ecosystems that are less pH buffered because of naturally reduced alkalinity. Methodology/Principal Findings To address CO2-induced changes to estuarine calcification, veliger larvae of two oyster species, the Eastern oyster (Crassostrea virginica), and the Suminoe oyster (Crassostrea ariakensis) were grown in estuarine water under four pCO2 regimes, 280, 380, 560 and 800 µatm, to simulate atmospheric conditions in the pre-industrial era, present, and projected future concentrations in 50 and 100 years respectively. CO2 manipulations were made using an automated negative feedback control system that allowed continuous and precise control over the pCO2 in experimental aquaria. Larval growth was measured using image analysis, and calcification was measured by chemical analysis of calcium in their shells. C. virginica experienced a 16% decrease in shell area and a 42% reduction in calcium content when pre-industrial and end of 21st century pCO2 treatments were compared. C. ariakensis showed no change to either growth or calcification. Both species demonstrated net calcification and growth, even when aragonite was undersaturated, a result that runs counter to previous expectations for invertebrate larvae that produce aragonite shells. Conclusions and Significance Our results suggest that temperate estuarine and coastal ecosystems are vulnerable to the expected changes in water chemistry due to elevated atmospheric CO2 and that biological responses to acidification, especially calcifying biota, will be species-specific and

  19. Familial calcific periarthritis.

    PubMed Central

    Hajiroussou, V J; Webley, M

    1983-01-01

    A family of 4 is described in which both children had calcific periarthritis affecting the shoulders, and the mother had radiological evidence of periarticular calcification near the left greater trochanter. PMID:6882045

  20. Vascular Calcification: an Update on Mechanisms and Challenges in Treatment

    PubMed Central

    Wu, Meiting; Rementer, Cameron; Giachelli, Cecilia M.

    2013-01-01

    Vascular calcification is highly associated with cardiovascular disease mortality, particularly in high risk patients with diabetes and chronic kidney diseases (CKD). In blood vessels, intimal calcification is associated with atherosclerosis, whereas medial calcification is a non-occlusive process which leads to increased vascular stiffness and reduced vascular compliance. In the valves, calcification of the leaflets can change the mechanical properties of the tissue and result in stenosis. For many decades, vascular calcification has been noted as a consequence of aging. Studies now confirm that vascular calcification is an actively regulated process and shares many features with bone development and metabolism. This review provides an update on the mechanisms of vascular calcification including the emerging roles of the RANK/RANKL/OPG triad, osteoclasts and microRNAs. Potential treatments adapted from osteoporosis and CKD treatments that are under investigation for preventing and/or regressing vascular calcification will also be reviewed. PMID:23456027

  1. Genetics in Arterial Calcification

    PubMed Central

    Rutsch, Frank; Nitschke, Yvonne; Terkeltaub, Robert

    2011-01-01

    Artery calcification reflects an admixture of factors such as ectopic osteochondral differentiation with primary host pathological conditions. We review how genetic factors, as identified by human genome-wide association studies, and incomplete correlations with various mouse studies, including knockout and strain analyses, fit into “pieces of the puzzle” in intimal calcification in human atherosclerosis, and artery tunica media calcification in aging, diabetes mellitus, and chronic kidney disease. We also describe in sharp contrast how ENPP1, CD73, and ABCC6 serve as “cogs in a wheel” of arterial calcification. Specifically, each is a minor component in the function of a much larger network of factors that exert balanced effects to promote and suppress arterial calcification. For the network to normally suppress spontaneous arterial calcification, the “cogs” ENPP1, CD73, and ABCC6 must be present and in working order. Monogenic ENPP1, CD73, and ABCC6 deficiencies each drive a molecular pathophysiology of closely related but phenotypically different diseases (generalized arterial calcification of infancy (GACI), pseudoxan-thoma elasticum (PXE) and arterial calcification caused by CD73 deficiency (ACDC)), in which premature onset arterial calcification is a prominent but not the sole feature. PMID:21852556

  2. Proton pumping accompanies calcification in foraminifera

    PubMed Central

    Toyofuku, Takashi; Matsuo, Miki Y.; de Nooijer, Lennart Jan; Nagai, Yukiko; Kawada, Sachiko; Fujita, Kazuhiko; Reichart, Gert-Jan; Nomaki, Hidetaka; Tsuchiya, Masashi; Sakaguchi, Hide; Kitazato, Hiroshi

    2017-01-01

    Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers. Here we show that calcification is driven by rapid transformation of bicarbonate into carbonate inside the cytoplasm, achieved by active outward proton pumping. Moreover, this proton flux is maintained over a wide range of pCO2 levels. We furthermore show that a V-type H+ ATPase is responsible for the proton flux and thereby calcification. External transformation of bicarbonate into CO2 due to the proton pumping implies that biomineralization does not rely on availability of carbonate ions, but total dissolved CO2 may not reduce calcification, thereby potentially maintaining the current global marine carbonate production. PMID:28128216

  3. Proton pumping accompanies calcification in foraminifera

    NASA Astrophysics Data System (ADS)

    Toyofuku, Takashi; Matsuo, Miki Y.; de Nooijer, Lennart Jan; Nagai, Yukiko; Kawada, Sachiko; Fujita, Kazuhiko; Reichart, Gert-Jan; Nomaki, Hidetaka; Tsuchiya, Masashi; Sakaguchi, Hide; Kitazato, Hiroshi

    2017-01-01

    Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers. Here we show that calcification is driven by rapid transformation of bicarbonate into carbonate inside the cytoplasm, achieved by active outward proton pumping. Moreover, this proton flux is maintained over a wide range of pCO2 levels. We furthermore show that a V-type H+ ATPase is responsible for the proton flux and thereby calcification. External transformation of bicarbonate into CO2 due to the proton pumping implies that biomineralization does not rely on availability of carbonate ions, but total dissolved CO2 may not reduce calcification, thereby potentially maintaining the current global marine carbonate production.

  4. A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study

    SciTech Connect

    Greuter, M. J. W.; Groen, J. M.; Nicolai, L. J.; Dijkstra, H.; Oudkerk, M.

    2009-11-15

    Purpose: The objective of this study is to quantify the influence of linear motion, calcification density, and temporal resolution on coronary calcium determination using multidetector computed tomography (MDCT), dual source CT (DSCT), and electron beam tomography (EBT) and to find a quantitative method which corrects for the influences of these parameters using a linear moving cardiac phantom. Methods: On a robotic arm with artificial arteries with four calcifications of increasing density, a linear movement was applied between 0 and 120 mm/s (step of 10 mm/s). The phantom was scanned five times on 64-slice MDCT, DSCT, and EBT using a standard acquisition protocol. The average Agatston, volume, and mass scores were determined for each velocity, calcification, and scanner. Susceptibility to motion was quantified using a cardiac motion susceptibility (CMS) index. Resemblance to EBT and physical volume and mass was quantified using a {Delta} index. Results: Increasing motion artifacts were observed at increasing velocities on all scanners, with increasing severity from EBT to DSCT to 64-slice MDCT. The calcium score showed a linear dependency on motion from which a correction factor could be derived. This correction factor showed a linear dependency on the mean calcification density with a good fit for all three scoring methods and all three scanners (0.73{<=}R{sup 2}{<=}0.95). The slope and offset of this correction factor showed a linear dependency on temporal resolution with a good fit for all three scoring methods and all three scanners (0.83{<=}R{sup 2}{<=}0.98). CMS was minimal for EBT and increasing values were observed for DSCT and highest values for 64-slice MDCT. CMS was minimal for mass score and increasing values were observed for volume score and highest values for Agatston score. For all densities and scoring methods DSCT showed on average the closest resemblance to EBT calcium scores. When using the correction factor, CMS index decreased on average by

  5. Middle Cerebral Artery Calcification

    PubMed Central

    Kao, Hung-Wen; Liou, Michelle; Chung, Hsiao-Wen; Liu, Hua-Shan; Tsai, Ping-Huei; Chiang, Shih-Wei; Chou, Ming-Chung; Peng, Giia-Sheun; Huang, Guo-Shu; Hsu, Hsian-He; Chen, Cheng-Yu

    2015-01-01

    Abstract Calcification of the middle cerebral artery (MCA) is uncommon in the healthy elderly. Whether calcification of the MCA is associated with cerebral ischemic stroke remains undetermined. We intended to investigate the association using Agatston calcium scoring of the MCA. This study retrospectively included 354 subjects with ischemic stroke in the MCA territory and 1518 control subjects who underwent computed tomography (CT) of the brain. We recorded major known risk factors for ischemic stroke, including age, gender, hypertension, diabetes mellitus, smoking, hyperlipidemia, and obesity, along with the MCA calcium burden, measured with the Agatston calcium scoring method. Univariate and modified logistic regression analyses were performed to examine the association between the MCA calcification and ischemic stroke. The univariate analyses showed significant associations of ischemic stroke with age, hypertension, diabetes mellitus, smoking, total MCA Agatston score, and the presence of calcification on both or either side of the MCA. Subjects with the presence of MCA calcification on both or either side of the MCA were 8.46 times (95% confidence interval, 4.93–14.53; P < 0.001) more likely to have a cerebral infarct than subjects without MCA calcification after adjustment for the major known risk factors, including age, hypertension, diabetes mellitus, and smoking. However, a higher degree of MCA calcification reflected by the Agatston score was not associated with higher risk of MCA ischemic stroke after adjustment for the confounding factors and presence of MCA calcification. These results suggest that MCA calcification is associated with ischemic stroke in the MCA territory. Further prospective studies are required to verify the clinical implications of the MCA calcification. PMID:26683969

  6. Coral calcification and ocean acidification

    USGS Publications Warehouse

    Jokiel, Paul L.; Jury, Christopher P.; Kuffner, Ilsa B.

    2016-01-01

    calcification and increases in Gnet. These relationships result in a correlation between Gnet and Ωarag, with both parameters being variables dependent on Pnet. Consequently the correlation between Gnet and Ωarag varies widely between different locations and times depending on the relative metabolic contributions of various calcifying and photosynthesizing organisms and local rates of carbonate dissolution. High rates of H+ efflux continue for several hours following the mid-day Gnet peak suggesting that corals have difficulty in shedding waste protons as described by the Proton Flux Model. DIC flux (uptake) tracks Pnet and Gnet and drops off rapidly after the photosynthesis-calcification maxima, indicating that corals can cope more effectively with the problem of limited DIC supply compared to the problem of eliminating H+. Predictive models of future global changes in coral and coral reef growth based on oceanic Ωarag must include the influence of future changes in localized Pnet on Gnet as well as changes in rates of reef carbonate dissolution. The correlation between Ωarag and Gnet over the diel cycle is simply the result of increasing pH due to photosynthesis that shifts the CO2-carbonate system equilibria to increase [CO32] relative to the other DIC components of [HCO3] and [CO2]. Therefore Ωarag closely tracks pH as an effect of Pnet, which also drives changes in Gnet. Measurements of DIC flux and H+ flux are far more useful than concentrations in describing coral metabolism dynamics. Coral reefs are systems that exist in constant disequilibrium with the water column.

  7. Intracranial calcifications. A pictorial review.

    PubMed

    Grech, R; Grech, S; Mizzi, A

    2012-09-01

    Brain calcifications are a common radiographic finding. The pathogenesis is diverse and ranges from benign physiological calcifications to a variety of pathological disorders. Whereas certain calcifications are considered an incidental finding, their presence can sometimes be crucial in making a specific diagnosis. Several pathological conditions affecting the brain parenchyma are associated with calcifications and their recognition and location might help in narrowing the differential. Knowledge of physiological calcifications is essential to avoid misinterpretation. This review illustrates a broad spectrum of CNS disorders associated with calcifications, and tries to highlight the salient radiological findings.

  8. Heart in An Eggshell Calcification: Idiopathic Calcific Constrictive Pericarditis

    PubMed Central

    Song, Bong Gun; Kang, Gu Hyun; Park, Yong Hwan; Chun, Woo Jung; Oh, Ju Hyeon

    2011-01-01

    Constrictive pericarditis is caused by fibrosis and calcification of the pericardium, which inhibits diastolic filling of the heart. Chest roentgenogram can show the calcification as a mass or sheet over the heart and computed tomography scan allows anatomic delineation of the pericardium and determines the extent of calcification. We reported a case of eggshell calcification of idiopathic chronic constrictive pericarditis diagnosed by echocardiography and multi-detector computed tomography.

  9. Associations between Thyroid Hormones, Calcification Inhibitor Levels and Vascular Calcification in End-Stage Renal Disease

    PubMed Central

    Meuwese, Christiaan Lucas; Olauson, Hannes; Qureshi, Abdul Rashid; Ripsweden, Jonaz; Barany, Peter; Vermeer, Cees; Drummen, Nadja; Stenvinkel, Peter

    2015-01-01

    Introduction Vascular calcification is a common, serious and elusive complication of end-stage renal disease (ESRD). As a pro-calcifying risk factor, non-thyroidal illness may promote vascular calcification through a systemic lowering of vascular calcification inhibitors such as matrix-gla protein (MGP) and Klotho. Methods and Material In 97 ESRD patients eligible for living donor kidney transplantation, blood levels of thyroid hormones (fT3, fT4 and TSH), total uncarboxylated MGP (t-ucMGP), desphospho-uncarboxylated MGP (dp-ucMGP), descarboxyprothrombin (PIVKA-II), and soluble Klotho (sKlotho) were measured. The degree of coronary calcification and arterial stiffness were assessed by means of cardiac CT-scans and applanation tonometry, respectively. Results fT3 levels were inversely associated with coronary artery calcification (CAC) scores and measures of arterial stiffness, and positively with dp-ucMGP and sKlotho concentrations. Subfractions of MGP, PIVKA-II and sKlotho did not associate with CAC scores and arterial stiffness. fT4 and TSH levels were both inversely associated with CAC scores, but not with arterial stiffness. Discussion The positive associations between fT3 and dp-ucMGP and sKlotho suggest that synthesis of MGP and Klotho is influenced by thyroid hormones, and supports a link between non-thyroidal illness and alterations in calcification inhibitor levels. However, the absence of an association between serum calcification inhibitor levels and coronary calcification/arterial stiffness and the fact that MGP and Klotho undergo post-translational modifications underscore the complexity of this association. Further studies, measuring total levels of MGP and membrane bound Klotho, should examine this proposed pathway in further detail. PMID:26147960

  10. Calcific Metamorphosis: A Review

    PubMed Central

    Siddiqui, Shoaib Haider; Mohamed, Ahmed Nabil

    2016-01-01

    Dental trauma to the permanent dentition can lead to clinical complications and its management may considerably challenge a practitioner. The incidence of pulp canal obliteration following dental trauma has been reported to be approximately 4 – 24%. Attempting to locate canals following calcific metamorphosis and negotiating it to full working length may lead to iatrogenic errors such as fractured instrument and perforation. This review article describes the possible etiology of Calcific Metamorphosis, its clinical and radiographic features as well as its management. PMID:27610067

  11. Control of guided hard-tissue regeneration using phosphorylated gelatin and OCT imaging of calcification

    NASA Astrophysics Data System (ADS)

    Ishii, Katsunori; Ma, Zhenhe; Ninomiya, Yoshihisa; Takegoshi, Minori; Kushibiki, Toshihiro; Yamamoto, Masaya; Hinds, Monica; Tabata, Yasuhiko; Wang, Ruikang K.; Awazu, Kunio

    2007-02-01

    Tendon and ligament are the transition tissues from a hard tissue to a soft tissue. The regenerative medicine of tendons needs reasonable biomaterials to regenerate precisely from the view point of composition and adhesion properties. In regenerative medicine of hard tissues, it has been reported that calcifications are influenced by phosphorylated proteins (phosphate groups) and the biomaterial possessing phosphate groups promote or inhibit the formation of HAP. We have studied to develop and evaluate the phosphorylated soft biomaterials, which is possible to control a calcification by the introduction ratio of phosphate groups, as biomaterials for tendon regeneration. In addition, we have studied measurement technologies. In the present study, we studied a FT-IR analysis of gelatins with different introduction ratio of phosphate groups, an evaluation of calcifications by the difference of introduction ratio of phosphate groups, and a fundamental survey on OCT imaging for calcifications of a gelatin and a phosphorylated gelatin. We use phosphorylated gelatins with different introduction ratios of phosphate group linked by ester bonds. The introduction ratios are measured by the FT-IR calibrated by a molybdenum blue method. Phosphorylated gelatin sheets were calcified using 1.5SBF soaking process and alternative soaking process. These gelatin sheets with different calcification conditions were measured using SD-OCT systems with 843nm centered wavelength SLD. As a result, we demonstrated that it was possible to measure the calcification on/in the gelatin sheets and sponges and phosphorylated using OCT. The main mechanism is the strong back scattering and the high scattering of deposited calcium particles.

  12. TWEAK favors phosphate-induced calcification of vascular smooth muscle cells through canonical and non-canonical activation of NFκB

    PubMed Central

    Hénaut, L; Sanz, A B; Martin-Sanchez, D; Carrasco, S; Villa-Bellosta, R; Aldamiz-Echevarria, G; Massy, Z A; Sanchez-Nino, M D; Ortiz, A

    2016-01-01

    Vascular calcification (VC) is associated with increased cardiovascular mortality in aging, chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM) and atherosclerosis. TNF-like weak inducer of apoptosis (TWEAK) recently emerged as a new biomarker for the diagnosis and prognosis of cardiovascular diseases. TWEAK binding to its functional receptor Fn14 was reported to promote several steps of atherosclerotic plaque progression. However, no information is currently available on the role of TWEAK/Fn14 on the development of medial calcification, which is highly prevalent in aging, CKD and T2DM. This study explored the involvement of TWEAK in human vascular smooth muscle cells (h-VSMCs) calcification in vitro. We report that TWEAK binding to Fn14 promotes inorganic phosphate-induced h-VSMCs calcification, favors h-VSMCs osteogenic transition, decreasing acta2 and myh11 and increasing bmp2 mRNA and tissue non-specific alkaline phosphatase (TNAP), and increases MMP9 activity. Blockade of the canonical NFκB pathway reduced by 80% TWEAK pro-calcific properties and decreased osteogenic transition, TNAP and MMP9 activity. Blockade of non-canonical NFκB signaling by a siRNA targeting RelB reduced by 20% TWEAK pro-calcific effects and decreased TWEAK-induced loss of h-VSMCs contractile phenotype and MMP9 activity, without modulating bmp2 mRNA or TNAP activity. Inhibition of ERK1/2 activation by a MAPK kinase inhibitor did not influence TWEAK pro-calcific properties. Our results suggest that TWEAK/Fn14 directly favors inorganic phosphate-induced h-VSMCs calcification by activation of both canonical and non-canonical NFκB pathways. Given the availability of neutralizing anti-TWEAK strategies, our study sheds light on the TWEAK/Fn14 axis as a novel therapeutic target in the prevention of VC. PMID:27441657

  13. Rectus Femoris Tendon Calcification

    PubMed Central

    Zini, Raul; Panascì, Manlio; Papalia, Rocco; Franceschi, Francesco; Vasta, Sebastiano; Denaro, Vincenzo

    2014-01-01

    Background: Since it was developed, hip arthroscopy has become the favored treatment for femoroacetabular impingement. Due to recent considerable improvements, the indications for this technique have been widely extended. Injuries of the rectus femoris tendon origin, after an acute phase, could result in a chronic tendinopathy with calcium hydroxyapatite crystal deposition, leading to pain and loss of function. Traditionally, this condition is addressed by local injection of anesthetic and corticosteroids or, when conservative measures fail, by open excision of the calcific lesion by an anterior approach. Purpose: To assess whether arthroscopic excision of calcification of the proximal rectus is a safe and effective treatment. Study Design: Case series; Level of evidence, 4. Methods: Outcomes were studied from 6 top amateur athletes (age range, 30-43 years; mean, 32.6 years) affected by calcification of the proximal rectus who underwent arthroscopic excision of the calcification. Patients were preoperatively assessed radiographically, and diagnosis was confirmed by a 3-dimensional computed tomography scan. To evaluate the outcome, standardized hip rating scores were used pre- and postoperatively (at 6 and 12 months): the Hip disability and Osteoarthritis Outcome Score, Oxford Hip Score, and Modified Harris Hip Score. Moreover, visual analog scales (VAS) for pain, sport activity level (SAL), and activities of daily living (ADL) were also used. Results: One year after surgery, all patients reported satisfactory outcomes, with 3 of 6 rating their return-to-sport level as high as preinjury level, and the remaining 3 with a percentage higher than 80%. Five patients ranked their ability to carry on daily activities at 100%. Statistical analysis showed significant improvement of the Oxford Hip Score, the Modified Harris Hip Score, and all 3 VAS subscales (pain, SAL, and ADL) from pre- to latest postoperative assessment (P < .05). Conclusion: Arthroscopic excision of

  14. Placental calcification: a metastatic process?

    PubMed

    Poggi, S H; Bostrom, K I; Demer, L L; Skinner, H C; Koos, B J

    2001-07-01

    Placental calcification commonly increases with gestational age. The mechanism of apatite mineralization probably involves one of three known mechanisms of tissue calcification: physiological (like bone), dystrophic (ischaemia-related) or metastatic (mineralization in a supersaturated environment). This study was designed to determine the mechanism of calcification by examining (1) the mineral content of placental calcifications in comparison to other physiological and pathological apatites, and (2) the expression of bone morphogenetic proteins (BMPs), which are important in physiological calcification, across gestational age. By energy-dispersive x-ray analysis (EDXA), the Ca/P weight ratio for apatitic mineral from mature calcifications was 2.00+/-0.05 (s.e.), which is similar to that for stones formed in a metastatic, supersaturated environment and lower than that observed in physiological calcification. Biologically active BMP, which was determined by bioassay, was demonstrated in mature and postmature placentae. The BMPs PLAB, PDF and related protein INSL-4 were identified by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), but their mRNA expression was independent of gestational age (7-41 weeks of gestation). We conclude that (1) the identified BMPs were not related directly to placental calcification, which argues against physiological calcification, and (2) the chemical composition of the apatitic mineral was suggestive of rapid formation in a supersaturated environment, which is consistent with a metastatic mechanism of calcification.

  15. Vascular Calcification: Mechanisms of Vascular Smooth Muscle Cell Calcification

    PubMed Central

    Leopold, Jane A.

    2014-01-01

    Vascular calcification is highly prevalent and, when present, is associated with major adverse cardiovascular events. Vascular smooth muscle cells play an integral role in mediating vessel calcification by undergoing differentiation to osteoblast-like cells and generating matrix vesicles that serve as a nidus for calcium-phosphate deposition in the vessel wall. Once believed to be a passive process, it is now recognized that vascular calcification is a complex and highly regulated process that involves activation of cellular signaling pathways, circulating inhibitors of calcification, genetic factors, and hormones. This review will examine several of the key mechanisms linking vascular smooth muscle cells to vessel calcification that may be targeted to reduce vessel wall mineralization and, thereby, reduce cardiovascular risk. PMID:25435520

  16. Arterial calcification: A new perspective?

    PubMed

    Nicoll, R; Henein, M

    2017-02-01

    Arterial calcification is commonly seen in atherosclerosis, chronic kidney disease (CKD) and diabetes and has long been considered a natural progression of atherosclerosis. Yet it is a systemic condition, occurring in a wide and diverse range of disease states and no medical treatment for cardiovascular disease has yet found a way to regress it; on the contrary, lipid-lowering therapy may worsen its progression. Although numerous studies have found associations between calcification and biomarkers, none has yet found a unifying mechanism that explains the calcification found in atherosclerosis, CKD or diabetes and many of the biomarkers are equally associated with atheroma development and cardiovascular events. Furthermore, both presence and absence of coronary artery calcification appear predictive of plaque rupture and cardiovascular events, indicating that the association is not causal. This suggests that we are no further forward in understanding the true nature of arterial calcification or its pathogenesis, other than noting that it is 'multifactorial'. This is because most researchers view arterial calcification as a progressive pathological condition which must be treated. Instead, we hypothesise that calcification develops as an immune response to endothelial injury, such as shear stress or oxidative stress in diabetics, and is consequently part of the body's natural defences. This would explain why it has been found to be protective of plaque rupture and why it is unresponsive to lipid-lowering agents. We propose that instead of attempting to treat arterial calcification, we should instead be attempting to prevent or treat all causes of endothelial injury.

  17. [Calcification in nonfunctioning transplanted kidneys].

    PubMed

    Peces, R; Sánchez, R J; Fernández, E J; Peces, C

    2007-01-01

    Failed renal allografts often are left in situ in patients who revert to chronic dialysis therapy or who undergo retransplantation. These organs may be the site of massive calcification despite their lack of physiological function. Calcification of an endstage renal allograft is sometimes found incidentally. We report here two patients who developed extensive calcification of the renal graft, one was on chronic hemodialysis and the other had a second renal transplantation with normal renal function. The precise pathogenesis of calcification and the factors which determine its tissue localization are unclear. Factors postulated to promote the development of metastatic calcification include an elevated calcium phosphate product, severe secondary hyperparathyroidism, aluminium toxicity and duration of dialytic therapy. In some cases local factors related with the chronic inflammatory rejection process are probably involved as well. However, the exact relative contribution of these factors remains unresolved. Unless specific clinical indications are present, transplant nephrectomy is not necessary for calcified end-stage renal allografts.

  18. Decrease in coccolithophore calcification and CO2 since the middle Miocene.

    PubMed

    Bolton, Clara T; Hernández-Sánchez, María T; Fuertes, Miguel-Ángel; González-Lemos, Saúl; Abrevaya, Lorena; Mendez-Vicente, Ana; Flores, José-Abel; Probert, Ian; Giosan, Liviu; Johnson, Joel; Stoll, Heather M

    2016-01-14

    Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly understood. This paper relates degree of coccolith calcification to cellular calcification, and presents the first records of size-normalized coccolith thickness spanning the last 14 Myr from tropical oceans. Degree of calcification was highest in the low-pH, high-CO2 Miocene ocean, but decreased significantly between 6 and 4 Myr ago. Based on this and concurrent trends in a new alkenone ɛp record, we propose that decreasing CO2 partly drove the observed trend via reduced cellular bicarbonate allocation to calcification. This trend reversed in the late Pleistocene despite low CO2, suggesting an additional regulator of calcification such as alkalinity.

  19. Decrease in coccolithophore calcification and CO2 since the middle Miocene

    PubMed Central

    Bolton, Clara T.; Hernández-Sánchez, María T.; Fuertes, Miguel-Ángel; González-Lemos, Saúl; Abrevaya, Lorena; Mendez-Vicente, Ana; Flores, José-Abel; Probert, Ian; Giosan, Liviu; Johnson, Joel; Stoll, Heather M.

    2016-01-01

    Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly understood. This paper relates degree of coccolith calcification to cellular calcification, and presents the first records of size-normalized coccolith thickness spanning the last 14 Myr from tropical oceans. Degree of calcification was highest in the low-pH, high-CO2 Miocene ocean, but decreased significantly between 6 and 4 Myr ago. Based on this and concurrent trends in a new alkenone ɛp record, we propose that decreasing CO2 partly drove the observed trend via reduced cellular bicarbonate allocation to calcification. This trend reversed in the late Pleistocene despite low CO2, suggesting an additional regulator of calcification such as alkalinity. PMID:26762469

  20. Decrease in coccolithophore calcification and CO2 since the middle Miocene

    NASA Astrophysics Data System (ADS)

    Bolton, Clara T.; Hernández-Sánchez, María T.; Fuertes, Miguel-Ángel; González-Lemos, Saúl; Abrevaya, Lorena; Mendez-Vicente, Ana; Flores, José-Abel; Probert, Ian; Giosan, Liviu; Johnson, Joel; Stoll, Heather M.

    2016-01-01

    Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly understood. This paper relates degree of coccolith calcification to cellular calcification, and presents the first records of size-normalized coccolith thickness spanning the last 14 Myr from tropical oceans. Degree of calcification was highest in the low-pH, high-CO2 Miocene ocean, but decreased significantly between 6 and 4 Myr ago. Based on this and concurrent trends in a new alkenone εp record, we propose that decreasing CO2 partly drove the observed trend via reduced cellular bicarbonate allocation to calcification. This trend reversed in the late Pleistocene despite low CO2, suggesting an additional regulator of calcification such as alkalinity.

  1. [Eight cases of calcific retropharyngeal tendinitis/retropharyngeal calcific tendinitis].

    PubMed

    Ohtsuka, Yuichiro; Chazono, Hideaki; Suzuki, Homare; Ohkuma, Yusuke; Sakurai, Toshioki; Hanazawa, Toyoyuki; Okamoto, Yoshitaka

    2013-11-01

    Calcific retropharyngeal tendinitis/retropharyngeal calcific tendinitis is an inflammation of the longus colli muscle caused by calcium hydroxyapatite crystal depositon in the longus colli muscle tendon. The three major symptoms are neck pain, limitations of neck movement, and swallowing pain. We treated 8 cases of calcific retropharyngeal tendinitis/ retropharyngeal calcific tendinitis. Each patient complained of neck pain, limitations of neck movement, and swallowing pain. The only local finding was the smooth swelling of the posterior pharyngeal wall. CT imaging showed calcification of the tendon of the longus colli muscle and a low density area in the retropharyngeal space without ring enhancement, suggesting a retropharyngeal abscess. MR imaging showed the smooth swelling of the retropharyngeal space and an increased signal intensity on T2-weighted MR imaging. Calcific retropharyngeal tendinitis heals spontaneously, and treatment is not usually required. However, the clinical outcomes are similar and can be confused with retropharyngeal abscess and pyogenic spondylitis, so antibiotics are administrated in many cases. In our report, 7 patients were hospitalized and were treated with the intravenous administration of antibiotics, while 1 patient who refused hospitalization was treated with an oral antibiotic. Steroids were administrated in 2 cases. The 7 patients who were hospitalized were cured within 6 to 10 days.

  2. Calcification prevention tablets

    NASA Technical Reports Server (NTRS)

    Lindsay, Geoffrey A.; Hasting, Michael A.; Gustavson, Michael A.

    1991-01-01

    Citric acid tablets, which slowly release citric acid when flushed with water, are under development by the Navy for calcification prevention. The citric acid dissolves calcium carbonate deposits and chelates the calcium. For use in urinals, a dispenser is not required because the tablets are non-toxic and safe to handle. The tablets are placed in the bottom of the urinal, and are consumed in several hundred flushes (the release rate can be tailored by adjusting the formulation). All of the ingredients are environmentally biodegradable. Mass production of the tablets on commercial tableting machines was demonstrated. The tablets are inexpensive (about 75 cents apiece). Incidences of clogged pipes and urinals were greatly decreased in long term shipboard tests. The corrosion rate of sewage collection pipe (90/10 Cu/Ni) in citric acid solution in the laboratory is several mils per year at conditions typically found in traps under the urinals. The only shipboard corrosion seen to date is of the yellow brass urinal tail pieces. While this is acceptable, the search for a nontoxic corrosion inhibitor is underway. The shelf life of the tablets is at least one year if stored at 50 percent relative humidity, and longer if stored in sealed plastic buckets.

  3. Calcification Changes of Mesozoic Calcareous Nannofossils

    NASA Astrophysics Data System (ADS)

    Bornemann, A.; Mutterlose, J.

    2003-12-01

    Studies on plankton samples and cultures revealed a variety factors which presumably control calcification and the size of coccoliths. Among others temperature, nutrients and seawater pH are thought to influence nannoplankton calcification. Whereas these studies only provide information of very short time intervals from hours to years, global climatic and oceanographic changes occur, however, on geological timescales. Thus their impact on nannofossil calcification and carbonate production can only be studied from the fossil record. We investigated DSDP sites from the western Atlantic of late Jurassic to early Cretaceous age in order to better understand long-term variations of the size of common nannofossil taxa and the resulting carbonate accumulation. The studied interval is characterized by two events in the pelagic carbonate record: (1) the onset of pelagic carbonate accumulation in the Tithonian, and (2) the Valanginian 'nannoconid crisis'. The Tithonian event went along with high abundances of strongly calcified nannofossils which presumably have an affinity to more oligotrophic surface water conditions. The mid Valanginian is marked by a positive carbon isotope excursion (CIE). This coincides with a sea level rise, volcanic activity and elevated atmospheric pCO2 levels. Greenhouse climate and an accelerated hydrological cycle presumably intensified weathering processes causing enhanced nutrient transfer from the continents into the oceans. Increasing surface water fertility is indicated by high abundances of nannofossils which possibly indicate more eutrophic conditions. In the western Tethys the CIE is predated by a sharp decrease in the abundance of rockforming nannoconids. This event is less pronounced in the western Atlantic due to a general scarcity of nannoconids. Low nannofossil carbonate accumulation rates and a dominance of less calcified taxa were observed and may reflect a general marine biocalcification crisis. Possible factors, which may have

  4. Genetic predisposition to calcific aortic stenosis and mitral annular calcification.

    PubMed

    Kutikhin, Anton G; Yuzhalin, Arseniy E; Brusina, Elena B; Ponasenko, Anastasia V; Golovkin, Alexey S; Barbarash, Olga L

    2014-09-01

    Valvular calcification precedes the development of valvular stenosis and may represent an important early phenotype for valvular heart disease. It is known that development of valvular calcification is likely to occur among members of a family. However, the knowledge about the role of genomic predictive markers in valvular calcification is still elusive. Aims of this review are to assess the impact of gene polymorphisms on risk and severity of aortic stenosis and mitral annular calcification. According to the results of the investigations carried out, all polymorphisms may be divided into the three groups conferring the level of evidence of their association with valvular stenosis. It is possible to conclude that apoB (XbaI, rs1042031, and rs6725189), ACE (rs4340), IL10 (rs1800896 and rs1800872), and LPA (rs10455872) gene polymorphisms may be associated with valvular calcific stenosis with a relatively high level of evidence. A number of other polymorphisms, such as PvuII polymorphism within the ORα gene, rs1042636 polymorphism within the CaSR gene, rs3024491, rs3021094, rs1554286, and rs3024498 polymorphisms within the IL10 gene, rs662 polymorphism within the PON1 gene, rs2276288 polymorphism within the MYO7A gene, rs5194 polymorphism within the AGTR1 gene, rs2071307 polymorphism within the ELN gene, rs17659543 and rs13415097 polymorphisms within the IL1F9 gene may correlate with a risk of calcific valve stenosis with moderate level of evidence. Finally, rs1544410 polymorphism within the VDR gene, E2 and E4 alleles within the apoE gene, rs6254 polymorphism within the PTH gene, and rs1800871 polymorphism within the IL10 gene may be associated with aortic stenosis with low level of evidence.

  5. Calcification Transformation of Diasporic Bauxite

    NASA Astrophysics Data System (ADS)

    Zhao, Qiuyue; Zhu, Xiaofeng; Lv, Guozhi; Zhang, Zimu; Yin, Zhengnan; Zhang, Tingan

    2016-06-01

    The disposal of red mud, which is a solid waste that is generated during the extraction of alumina from bauxite, is one of major problems faced by the aluminum industry. Alkali in red mud seeping under the soil may pollute land and water. The Northeastern University, China, has proposed a calcification-carbonation method to deal with low-grade bauxite or red mud. Its main purpose is to change the equilibrium phase of red mud to 2CaO·SiO2 and CaCO3 hydrometallurgically, so that recomposed alkali-free red mud can be widely used. We conducted calcification transformation experiments using diasporic bauxite sampled from Wenshan, and investigated the effects of parameters such as diasporic bauxite grain size, temperature and treatment time on the calcification transformation digestion rate, which is also termed the calcification transformation rate (CTR). The main phase in the calcification transformation slag (CTS) is hydrogarnet with different grain sizes. The CTR increases with decrease in diasporic bauxite grain size, or increase in temperature or reaction time. The CTR reaches a maximum of 87% after 120 min reaction at 240°C. The Na2O/Al2O3 ratio decreases with increase in temperature and reaches 1.5. The sodium content in the CTS decreases with increasing reaction time and is lower than that in the red mud treated using the Bayer process (4-12%).

  6. Effect of calcium carbonate saturation of seawater on coral calcification

    USGS Publications Warehouse

    Gattuso, J.-P.; Frankignoulle, M.; Bourge, I.; Romaine, S.; Buddemeier, R.W.

    1998-01-01

    The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (l) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.

  7. Reduction of calcification by various treatments in cardiac valves.

    PubMed

    Rao, K P; Shanthi, C

    1999-01-01

    The importance of glutaraldehyde pretreated bioprosthetic heart valves fabricated from bovine pericardium or porcine aortic valves is well realized in the management of valvular heart diseases. But, calcification limits the durability and is the most frequent cause of failure of these bioprosthetic heart valves. Various research groups in the world are actively involved in describing, understanding, and preventing calcification of bioprosthetic heart valves. Since there is no satisfactory clinical means for preventing or treating this disorder, attempts are made to improve the anticalcification properties of the replacement valves in the preparation stage itself. Research in this area is very active, and many newer approaches are made to mitigate the problem. An attempt has been made in the present article to review various theories put forward to explain the causative factors involved and mechanistic aspects of biocalcification and to present various strategies attempted for the prevention of calcification with the special feature on the work done in the area in our laboratory.

  8. Intracranial calcification in central diabetes insipidus.

    PubMed

    Al-Kandari, Salwa Ramadan; Pandey, Tarun; Badawi, Mona H

    2008-01-01

    Intracranial calcification is a known but extremely rare complication of diabetes insipidus. To date, only 16 patients have been reported and all had the peripheral (nephrogenic) type of diabetes insipidus. We report a child with intracranial calcification complicating central diabetes insipidus. We also report a child with nephrogenic diabetes insipidus, and compare the patterns of intracranial calcification.

  9. CT of schistosomal calcification of the intestine

    SciTech Connect

    Fataar, S.; Bassiony, H.; Satyanath, S.; Rudwan, M.; Hebbar, G.; Khalifa, A.; Cherian, M.J.

    1985-01-01

    The spectrum of schistosomal colonic calcification on abdominal radiographs has been described. The appearance on computed tomography (CT) is equally distinctive and occurs with varying degrees of genitourinary calcification. The authors have experience in three cases with the appearance on CT of intestinal calcification due to schistosomiasis.

  10. Arterial calcification: friend or foe?

    PubMed

    Nicoll, Rachel; Henein, Michael Y

    2013-07-31

    There is a significant relationship between the presence, extent and progression of coronary artery calcification (CAC) and cardiovascular (CV) events and mortality in both CV and renal patients and CAC scoring can provide improved predictive ability over risk factor scoring alone. There is also a close relationship between CAC presence and atherosclerotic plaque burden, with angiography studies showing very high sensitivity but poor specificity of CAC score for predicting obstructive disease. Nevertheless, there are objections to CAC screening because of uncertainties and lack of studies showing improved outcome. Furthermore, histopathology studies indicate that heavily calcified plaque is unlikely to result in a CV event, while the vulnerable plaque tends to be uncalcified or 'mixed', suggesting that calcification may be protective. This scenario highlights a number of paradoxes, which may indicate that the association between CAC and CV events is spurious, following from the adoption of CAC as a surrogate for high plaque burden, which itself is a surrogate for the presence of vulnerable plaque. Since studies indicate that arterial calcification is a complex, organised and regulated process similar to bone formation, there is no particular reason why it should be a reliable indicator of either the plaque burden or the risk of a future CV event. We suggest that it is time to divorce arterial calcification from atherosclerosis and to view it as a distinct pathology in its own right, albeit one which frequently coexists with atherosclerosis and is related to it for reasons which are not yet fully understood.

  11. Genetics and molecular biology of brain calcification.

    PubMed

    Deng, Hao; Zheng, Wen; Jankovic, Joseph

    2015-07-01

    Brain calcification is a common neuroimaging finding in patients with neurological, metabolic, or developmental disorders, mitochondrial diseases, infectious diseases, traumatic or toxic history, as well as in otherwise normal older people. Patients with brain calcification may exhibit movement disorders, seizures, cognitive impairment, and a variety of other neurologic and psychiatric symptoms. Brain calcification may also present as a single, isolated neuroimaging finding. When no specific cause is evident, a genetic etiology should be considered. The aim of the review is to highlight clinical disorders associated with brain calcification and provide summary of current knowledge of diagnosis, genetics, and pathogenesis of brain calcification.

  12. Gla-rich protein is a novel vitamin K-dependent protein present in serum that accumulates at sites of pathological calcifications.

    PubMed

    Viegas, Carla S B; Cavaco, Sofia; Neves, Pedro L; Ferreira, Ana; João, Alexandre; Williamson, Matthew K; Price, Paul A; Cancela, M Leonor; Simes, Dina C

    2009-12-01

    Mineralization of soft tissues is an abnormal process that occurs in any body tissue and can greatly increase morbidity and mortality. Vitamin K-dependent (VKD) proteins play a crucial role in these processes; matrix Gla protein is considered one of the most relevant physiological inhibitors of soft tissue calcification know to date. Several studies have suggested that other, still unknown, VKD proteins might also be involved in soft tissue calcification pathologies. We have recently identified in sturgeon a new VKD protein, Gla-rich protein (GRP), which contains the highest ratio between number of Gla residues and size of the mature protein so far identified. Although mainly expressed in cartilaginous tissues of sturgeon, in rat GRP is present in both cartilage and bone. We now show that GRP is a circulating protein that is also expressed and accumulated in soft tissues of rats and humans, including the skin and vascular system in which, when affected by pathological calcifications, GRP accumulates at high levels at sites of mineral deposition, indicating an association with calcification processes. The high number of Gla residues and consequent mineral binding affinity properties strongly suggest that GRP may directly influence mineral formation, thereby playing a role in processes involving connective tissue mineralization.

  13. [Matrix Gla protein as natural inhibitor of vascular calcification and potential treatment target].

    PubMed

    Mayer, Otto

    2016-01-01

    Vascular calcification was once regarded as an advanced stage of atherosclerosis only. However, calcification is currently considered as highly regulated and potentially reversible process.Matrix Gla protein (MGP) represents natural inhibitor of vascular calcification, whereas vitamin K is key co-factor of its maturation to the active form. There is accumulating evidence that vitamin K status and corresponding MGP activity may influence cardiovascular risk. This review summarizes pathophysiological mechanism and recent evidence relative to MGP. Moreover, available data concerning vitamin K supplementation are depicted.

  14. Calcific retropharyngeal tendinitis. [Radiological findings

    SciTech Connect

    Karasick, D.; Karasick, S.

    1981-12-01

    Calcific retropharyngeal tendinitis is an imflammation of the longus colli muscle tendon which is located on the anterior surface of the verterbral column extending from the atlas to the third thoracic vertebra. The acute inflammatory condition is selflimiting with symptoms consisting of a gradually increasing neck pain often associated with throat pain and difficulty swallowing. The pain is aggravated by head and neck movement. Clinically the condition can be confused with retropharyngeal absecess, meningitis, infectious spondylitis, and post-traumatic muscle spasm. The radiographic features of this condition consist of pre-vertebral soft tissue swelling from C1 to C4 and amorphous calcific density in the longus colli tendon anterior to the body of C2 and inferior to the anterior arch of C1.

  15. [Differential diagnosis of intrasinusal calcifications].

    PubMed

    Hernández Montero, E; Martínez Berganza, R; Carmen Sampériz, L

    2004-01-01

    We present a case of a patient with a sinusitis of three months evolution. The CT scan showed an occupation of the middle meatus of the left nasal fossa with alergic polyps and a total opacification of the left maxillary sinus with calcifications, that makes to discard the metalic on dental nature of an intrasinusal body, and other chronic granulomatous processes. The correct surgical restauration of the osteomeotal complex obtained the complete resolution of the process.

  16. Pleural calcification in northwest Greece

    SciTech Connect

    Bazas, T.; Oakes, D.; Gilson, J.C.; Bazas, B.; McDonald, J.C.

    1985-12-01

    Mass miniature radiography in 1969 detected a high prevalence of pleural calcification in three villages in northwest Greece. In 1980 a survey of a 15% sample of the population over the age of 10 was carried out with a 80% response rate. Full-size radiographs, ventilatory capacity measurements, and a detailed questionnaire on respiratory symptoms, type of work, and residence were used. Independent classification of the 408 films by two readers using the ILO/UC scheme showed very few small opacities but a very high prevalence of pleural calcification first evident in young adults and rising to 70% in the elderly. The overall prevalence was 34.7% in men and 21.5% in women. A comparison with the 1969 survey showed a progression rate of 5% per annum. In neither sex was there a significant relation of pleural calcification to smoking, ventilatory capacity, nor type of work, though those classified as field croppers had a slightly higher prevalence. There was no obvious evidence of increased lung cancer or mesothelioma in the village. The agent responsible for this apparently benign condition was not identified.

  17. Influence of liquid lubricant properties on their performance

    NASA Technical Reports Server (NTRS)

    Wedeven, V.

    1972-01-01

    The influence of lubricant properties on performance is considered in connection with various mechanisms of lubrication. The effects of temperature and pressure on viscosity, which is important in hydrodynamic and elastohydrodynamic lubrication, is presented using a correlation postulated by Roelands. Under elastohydrodynamic conditions it is important to distinguish between the influence of lubricant properties within the inlet region and the Hertz region since each performs different functions. The role of lubricant transport properties such as surface tension is considered in connection with lubricant starvation. Since the lubrication of practical surfaces usually involves boundary as well as hydrodynamic mechanisms, both the chemical and physical properties significantly influence the lubricant's performance.

  18. Incidental Anterior Cruciate Ligament Calcification: Case Report

    PubMed Central

    Hayashi, Hisami; Fischer, Hans

    2016-01-01

    The calcification of knee ligaments is a finding noted only in a handful of case reports. The finding of an anterior cruciate ligament calcification has been reported once in the literature. Comparable studies involving the posterior cruciate ligament, medial collateral ligament and an ossicle within the anterior cruciate ligament are likewise discussed in reports of symptomatic patients. We report a case of incidentally discovered anterior cruciate ligament calcification. We discuss the likely etiology and clinical implications of this finding. PMID:27200163

  19. Senile Cardiac Calcification Syndrome: A Rare Case of Extensive Calcification of Left Ventricular Papillary Muscle

    PubMed Central

    Kim, Eun Jin; Song, Bong Gun; Sohn, Hyung Rae; Hong, Su-Min; Park, Dong Won; Heo, Seung Hye; Kim, Kye Yeon; Cho, Wook-Hyun; Choi, Suk-Koo

    2011-01-01

    Extensive papillary muscle calcification is uncommon and only scarce literature about causes and the clinical significance is available, whereas small calcific deposits are common findings in elderly people and are located most commonly at the apex. Papillary muscle calcification has been associated with coronary artery disease, dilated cardiomyopathy, mitral valve disease, hypercalcemia, and increased calcium phosphate product in end stage renal disease. We reported a rare case of extensive calcification of anterolateral papillary muscle diagnosed by echocardiography and multidetector computed tomography.

  20. The Role of AGE/RAGE Signaling in Diabetes-Mediated Vascular Calcification

    PubMed Central

    2016-01-01

    AGE/RAGE signaling has been a well-studied cascade in many different disease states, particularly diabetes. Due to the complex nature of the receptor and multiple intersecting pathways, the AGE/RAGE signaling mechanism is still not well understood. The purpose of this review is to highlight key areas of AGE/RAGE mediated vascular calcification as a complication of diabetes. AGE/RAGE signaling heavily influences both cellular and systemic responses to increase bone matrix proteins through PKC, p38 MAPK, fetuin-A, TGF-β, NFκB, and ERK1/2 signaling pathways in both hyperglycemic and calcification conditions. AGE/RAGE signaling has been shown to increase oxidative stress to promote diabetes-mediated vascular calcification through activation of Nox-1 and decreased expression of SOD-1. AGE/RAGE signaling in diabetes-mediated vascular calcification was also attributed to increased oxidative stress resulting in the phenotypic switch of VSMCs to osteoblast-like cells in AGEs-induced calcification. Researchers found that pharmacological agents and certain antioxidants decreased the level of calcium deposition in AGEs-induced diabetes-mediated vascular calcification. By understanding the role the AGE/RAGE signaling cascade plays diabetes-mediated vascular calcification will allow for pharmacological intervention to decrease the severity of this diabetic complication. PMID:27547766

  1. New concept of vascular calcification and metabolism.

    PubMed

    Nakagami, Hironori; Osako, Mariana K; Morishita, Ryuichi

    2011-01-01

    Vascular calcification is recently considered as one of the major complications and an independent risk factor of cardiovascular diseases. Although vascular calcification was commonly regarded as a passive process of mineral adsorption or precipitation, it tends to be an active process associated with the expression of growth factors, matrix proteins, and other bone-related proteins. There are 2 main types of vascular calcification. Intimal calcification is found in atherosclerotic plaques and is associated with the vascular events such as myocardial infarction. Medial calcification is usually associated with age and chronic kidney disease patients, which leads to increased vascular stiffness and reduced vascular compliance. Interestingly, our vascular calcification model using ApoE deficient mice showed intima calcification at sites of atherosclerotic plaques under high fat diet with ovariectomy. Thus, lipid metabolism is one of the therapeutic targets to prevent intima calcification of aorta. Previously we reported that ezetimibe significantly prevented atherosclerosis through lipid-lowering effects in ApoE-deficient mice. Based on these findings, we speculate that ezetimibe might prevent aortic intima calcification, which may give us the benefits to decrease vascular events.

  2. Calcification in bleached and unbleached Montastraea faveolata: evaluating the role of oxygen and glycerol

    NASA Astrophysics Data System (ADS)

    Colombo-Pallotta, M. F.; Rodríguez-Román, A.; Iglesias-Prieto, R.

    2010-12-01

    All reef-building corals are symbiotic with dinoflagellates of the genus Symbiodinium, which influences many aspects of the host’s physiology including calcification. Coral calcification is a biologically controlled process performed by the host that takes place several membranes away from the site of photosynthesis performed by the symbiont. Although it is well established that light accelerates CaCO3 deposition in reef-building corals (commonly referred to as light-enhanced calcification), the complete physiological mechanism behind the process is not fully understood. To better comprehend the coral calcification process, a series of laboratory experiments were conducted in the major Caribbean reef-building species Montastraea faveolata, to evaluate the effect of glycerol addition and/or the super-saturation of oxygen in the seawater. These manipulations were performed in bleached and unbleached corals, to separate the effect of photosynthesis from calcification. The results suggest that under normal physiological conditions, a 42% increase in seawater oxygen concentration promotes a twofold increase in dark-calcification rates relative to controls. On the other hand, the results obtained using bleached corals suggest that glycerol is required, as a metabolic fuel, in addition to an oxygenic environment in a symbiosis that has been disrupted. Also, respiration rates in symbiotic corals that were pre-incubated in light conditions showed a kinetic limitation, whereas corals that were pre-incubated in darkness were oxygen limited, clearly emphasizing the role of oxygen in this regard. These findings indicate that calcification in symbiotic corals is not strictly a “light-enhanced” or “dark-repressed” process, but rather, the products of photosynthesis have a critical role in calcification, which should be viewed as a “photosynthesis-driven” process. The results presented here are discussed in the context of the current knowledge of the coral

  3. Isolated posterior cruciate ligament calcification

    PubMed Central

    Koukoulias, Nikolaos E; Papastergiou, Stergios G

    2011-01-01

    The authors present a case of calcified posterior cruciate ligament (PCL). A 61-year-old female presented in our department reporting 12 months history of knee pain that was getting worse during the night. The patient was under medication for epileptic seizure, osteoporosis and hyperthyroidism. X-rays demonstrated calcification of the PCL. CT and MRI excluded any other intra-articular and extra-articular pathology. Arthroscopic debridement of the calcium deposits was performed and the symptoms resolved immediately, while the postoperative x-rays were normal. Histological examination confirmed the calcium nature of the lesion. Two years postoperatively the patient remains asymptomatic. PMID:22669889

  4. Urease-induced calcification of segmented polymer hydrogels - a step towards artificial biomineralization.

    PubMed

    Rauner, Nicolas; Meuris, Monika; Dech, Stephan; Godde, Julia; Tiller, Joerg C

    2014-09-01

    Natural organic/inorganic composites, such as nacre, bones and teeth, are perfectly designed materials with exceptional mechanical properties. Numerous approaches have been taken to synthetically prepare such composites. The presented work describes a new way of mineralizing bulk materials on a large scale following the approach of bioinduced mineralization. To this end, a series of polymer conetworks with entrapped urease were prepared. After polymerization, the entrapped urease shows high enzymatic activity. The bioactive polymer conetworks were then treated with an aqueous mixture of urea and CaCl2. The urease-induced calcification indeed allows formation of carbonate crystals exclusively within the hydrogel even at room temperature. The influence of network composition, degree of cross-linking, immobilized urease concentration and temperature of calcification were investigated. By varying these parameters, spherical, monolithic clusters, as well as bar-like nanocrystals with different aspect ratios in spherical or dendritic arrays, are formed. The grown nanocrystals improve the stiffness of the starting material by up to 700-fold, provided that the microstructure shows a dense construction without pores and strong interaction between crystals and network. The process has the potential to generate a new class of hybrid materials that would be available on the macroscopic scale for use in lightweight design and medicine.

  5. Aortic Valve Calcification in Mild Primary Hyperparathyroidism

    PubMed Central

    Iwata, Shinichi; Walker, Marcella Donovan; Di Tullio, Marco R.; Hyodo, Eiichi; Jin, Zhezhen; Liu, Rui; Sacco, Ralph L.; Homma, Shunichi

    2012-01-01

    Context: It is unclear whether cardiovascular disease is present in primary hyperparathyroidism (PHPT). Objective: Aortic valve structure and function were compared in PHPT patients and population-based controls. Design: This is a case-control study. Setting: The study was conducted in a university hospital metabolic bone disease unit. Participants: We studied 51 patients with PHPT and 49 controls. Outcome Measures: We measured the aortic valve calcification area and the transaortic pressure gradient. Results: Aortic valve calcification area was significantly higher in PHPT (0.24 ± 0.02 vs. 0.17 ± 0.02 cm2, p<0.01), although there was no difference in the peak transaortic pressure gradient, a functional measure of valvular calcification (5.6 ± 0.3 vs. 6.0 ± 0.3 mm Hg, P = 0.39). Aortic valve calcification area was positively associated with PTH (r = 0.34; P < 0.05) but not with serum calcium, phosphorus, or 25-hydroxyvitamin D levels or with calcium-phosphate product. Serum PTH level remained an independent predictor of aortic valve calcification area after adjustment for age, sex, body mass index, smoking status, history of hypercholesterolemia and hypertension, and estimated glomerular filtration rate. Conclusions: Mild PHPT is associated with subclinical aortic valve calcification. PTH, but not serum calcium concentration, predicted aortic valve calcification. PTH was a more important predictor of aortic valve calcification than well-accepted cardiovascular risk factors. PMID:22031523

  6. Vascular Adventitia Calcification and Its Underlying Mechanism

    PubMed Central

    Li, Na; Cheng, Wenli; Huang, Tiequn; Yuan, Jie; Wang, Xi; Song, Meiyue

    2015-01-01

    Previous research on vascular calcification has mainly focused on the vascular intima and media. However, we show here that vascular calcification may also occur in the adventitia. The purpose of this work is to help elucidate the pathogenic mechanisms underlying vascular calcification. The calcified lesions were examined by Von Kossa staining in ApoE−/− mice which were fed high fat diets (HFD) for 48 weeks and human subjects aged 60 years and older that had died of coronary heart disease, heart failure or acute renal failure. Explant cultured fibroblasts and smooth muscle cells (SMCs)were obtained from rat adventitia and media, respectively. After calcification induction, cells were collected for Alizarin Red S staining. Calcified lesions were observed in the aorta adventitia and coronary artery adventitia of ApoE-/-mice, as well as in the aorta adventitia of human subjects examined. Explant culture of fibroblasts, the primary cell type comprising the adventitia, was successfully induced for calcification after incubation with TGF-β1 (20 ng/ml) + mineralization media for 4 days, and the phenotype conversion vascular adventitia fibroblasts into myofibroblasts was identified. Culture of SMCs, which comprise only a small percentage of all cells in the adventitia, in calcifying medium for 14 days resulted in significant calcification.Vascular calcification can occur in the adventitia. Adventitia calcification may arise from the fibroblasts which were transformed into myofibroblasts or smooth muscle cells. PMID:26148272

  7. Mechanisms and Clinical Consequences of Vascular Calcification

    PubMed Central

    Zhu, Dongxing; Mackenzie, Neil C. W.; Farquharson, Colin; MacRae, Vicky E.

    2012-01-01

    Vascular calcification has severe clinical consequences and is considered an accurate predictor of future adverse cardiovascular events, including myocardial infarction and stroke. Previously vascular calcification was thought to be a passive process which involved the deposition of calcium and phosphate in arteries and cardiac valves. However, recent studies have shown that vascular calcification is a highly regulated, cell-mediated process similar to bone formation. In this article, we outline the current understanding of key mechanisms governing vascular calcification and highlight the clinical consequences. By understanding better the molecular pathways and genetic circuitry responsible for the pathological mineralization process novel drug targets may be identified and exploited to combat and reduce the detrimental effects of vascular calcification on human health. PMID:22888324

  8. Physiopathology of intratendinous calcific deposition

    PubMed Central

    2012-01-01

    In calcific tendinopathy (CT), calcium deposits in the substance of the tendon, with chronic activity-related pain, tenderness, localized edema and various degrees of decreased range of motion. CT is particularly common in the rotator cuff, and supraspinatus, Achilles and patellar tendons. The presence of calcific deposits may worsen the clinical manifestations of tendinopathy with an increase in rupture rate, slower recovery times and a higher frequency of post-operative complications. The aetiopathogenesis of CT is still controversial, but seems to be the result of an active cell-mediated process and a localized attempt of the tendon to compensate the original decreased stiffness. Tendon healing includes many sequential processes, and disturbances at different stages of healing may lead to different combinations of histopathological changes, diverting the normal healing processes to an abnormal pathway. In this review, we discuss the theories of pathogenesis behind CT. Better understanding of the pathogenesis is essential for development of effective treatment modalities and for improvement of clinical outcomes. PMID:22917025

  9. Coccolithophore calcification response to past ocean acidification and climate change.

    PubMed

    O'Dea, Sarah A; Gibbs, Samantha J; Bown, Paul R; Young, Jeremy R; Poulton, Alex J; Newsam, Cherry; Wilson, Paul A

    2014-11-17

    Anthropogenic carbon dioxide emissions are forcing rapid ocean chemistry changes and causing ocean acidification (OA), which is of particular significance for calcifying organisms, including planktonic coccolithophores. Detailed analysis of coccolithophore skeletons enables comparison of calcite production in modern and fossil cells in order to investigate biomineralization response of ancient coccolithophores to climate change. Here we show that the two dominant coccolithophore taxa across the Paleocene-Eocene Thermal Maximum (PETM) OA global warming event (~56 million years ago) exhibited morphological response to environmental change and both showed reduced calcification rates. However, only Coccolithus pelagicus exhibits a transient thinning of coccoliths, immediately before the PETM, that may have been OA-induced. Changing coccolith thickness may affect calcite production more significantly in the dominant modern species Emiliania huxleyi, but, overall, these PETM records indicate that the environmental factors that govern taxonomic composition and growth rate will most strongly influence coccolithophore calcification response to anthropogenic change.

  10. Calcification

    MedlinePlus

    ... joints, and soft tissue tumors. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathologic ... PA: Elsevier Saunders; 2015:chap 26. Kumar V, Abbas AK, Aster JC. Cellular responses to stress and ...

  11. Influence of liquid lubricant properties on their performance.

    NASA Technical Reports Server (NTRS)

    Wedeven, V.

    1972-01-01

    The influence of lubricant properties on performance is considered in connection with various mechanisms of lubrication. The effects of temperature and pressure on viscosity, which is important in hydrodynamic and elastohydrodynamic lubrication, is presented using a correlation postulated by Roelands. Under elastohydrodynamic conditions it is important to distinguish between the influence of lubricant properties within the inlet region and the Hertz region since each performs different functions. The role of lubricant transport properties such as surface tension is considered in connection with lubricant starvation.

  12. Evidence of Pineal Gland Calcification on CBCT is Not Insignificant: What Else You Might Discover about Your Patient.

    PubMed

    Fore, Stacy

    2016-01-01

    The use of CBCT technology in the dental office is increasing rapidly. These scans provide information on anatomy not previously evaluated with traditional 2D films. One structure often mentioned in a CBCT radiology report is the pineal gland. The pineal gland will show evidence of calcification, but this calcification is often dismissed as a normal aging process. This review of the function and influence of the pineal gland may influence the doctor to complete further evaluation of the patient.

  13. Corneal calcification after amniotic membrane transplantation

    PubMed Central

    Anderson, S B; de Souza, R Ferreira; Hofmann-Rummelt, C; Seitz, B

    2003-01-01

    Background/aims: Amniotic membrane transplantation (AMT) has become well established as a treatment for chronic epithelial defects, conjunctival reconstruction, and partial limbal cell deficiency. The aim of this study was to describe cases of corneal calcification following AMT and to search for risk factors that might predispose to this unusual finding. Methods: Details of 117 AMTs on 93 corneas of 91 patients with a follow up period of at least 1 month performed since 1999 were collected prospectively. In those with calcification clinical photographs were studied and the medical records retrospectively examined. Results: 15 calcifications in 117 AMTs (12.8%) were identified, occurring 3–17 (median 6.1) weeks after AMT, during a follow up period of 4–151 (median 25) weeks. Overall epithelial healing rate was 83%. Calcification covered a surface area between 0.7–40.5 mm2 maximum size with varied morphology. The primary diagnosis was diverse. Risk factors included the use of phosphate eye drops and pre-existing calcification in the operative or other eye. No patient with a “patch” AMT developed calcification. Conclusions: Corneal calcification occurs after some cases of AMT. A common risk factor was the postoperative use of phosphate containing eye drops. PMID:12714401

  14. Pathology of Human Coronary and Carotid Artery Atherosclerosis and Vascular Calcification in Diabetes Mellitus.

    PubMed

    Yahagi, Kazuyuki; Kolodgie, Frank D; Lutter, Christoph; Mori, Hiroyoshi; Romero, Maria E; Finn, Aloke V; Virmani, Renu

    2017-02-01

    The continuing increase in the prevalence of diabetes mellitus in the general population is predicted to result in a higher incidence of cardiovascular disease. Although the mechanisms of diabetes mellitus-associated progression of atherosclerosis are not fully understood, at clinical and pathological levels, there is an appreciation of increased disease burden and higher levels of arterial calcification in these subjects. Plaques within the coronary arteries of patients with diabetes mellitus generally exhibit larger necrotic cores and significantly greater inflammation consisting mainly of macrophages and T lymphocytes relative to patients without diabetes mellitus. Moreover, there is a higher incidence of healed plaque ruptures and positive remodeling in hearts from subjects with type 1 diabetes mellitus and type 2 diabetes mellitus, suggesting a more active atherogenic process. Lesion calcification in the coronary, carotid, and other arterial beds is also more extensive. Although the role of coronary artery calcification in identifying cardiovascular disease and predicting its outcome is undeniable, our understanding of how key hormonal and physiological alterations associated with diabetes mellitus such as insulin resistance and hyperglycemia influence the process of vascular calcification continues to grow. Important drivers of atherosclerotic calcification in diabetes mellitus include oxidative stress, endothelial dysfunction, alterations in mineral metabolism, increased inflammatory cytokine production, and release of osteoprogenitor cells from the marrow into the circulation. Our review will focus on the pathophysiology of type 1 diabetes mellitus- and type 2 diabetes mellitus-associated vascular disease with particular focus on coronary and carotid atherosclerotic calcification.

  15. IN718 Additive Manufacturing Properties and Influences

    NASA Technical Reports Server (NTRS)

    Lambert, Dennis M.

    2015-01-01

    The results of tensile, fracture, and fatigue testing of IN718 coupons produced using the selective laser melting (SLM) additive manufacturing technique are presented. The data have been "sanitized" to remove the numerical values, although certain references to material standards are provided. This document provides some knowledge of the effect of variation of controlled build parameters used in the SLM process, a snapshot of the capabilities of SLM in industry at present, and shares some of the lessons learned along the way. For the build parameter characterization, the parameters were varied over a range that was centered about the machine manufacturer's recommended value, and in each case they were varied individually, although some co-variance of those parameters would be expected. Tensile, fracture, and high-cycle fatigue properties equivalent to wrought IN718 are achievable with SLM-produced IN718. Build and post-build processes need to be determined and then controlled to established limits to accomplish this. It is recommended that a multi-variable evaluation, e.g., design-of experiment (DOE), of the build parameters be performed to better evaluate the co-variance of the parameters.

  16. IN718 Additive Manufacturing Properties and Influences

    NASA Technical Reports Server (NTRS)

    Lambert, Dennis M.

    2015-01-01

    The results of tensile, fracture, and fatigue testing of IN718 coupons produced using the selective laser melting (SLM) additive manufacturing technique are presented. The data has been "generalized" to remove the numerical values, although certain references to material standards are provided. This document provides some knowledge of the effect of variation of controlled build parameters used in the SLM process, a snapshot of the capabilities of SLM in industry at present, and shares some of the lessons learned along the way. For the build parameter characterization, the parameters were varied over a range about the machine manufacturer's recommended value, and in each case they were varied individually, although some co-variance of those parameters would be expected. SLM-produced IN718, tensile, fracture, and high-cycle fatigue properties equivalent to wrought IN718 are achievable. Build and post-build processes need to be determined and then controlled to established limits to accomplish this. It is recommended that a multi-variable evaluation, e.g., design-of-experiment (DOE), of the build parameters be performed to better evaluate the co-variance of the parameters.

  17. Factors influencing the dielectric properties of agricultural and food products.

    PubMed

    Nelson, Stuart O; Trabelsi, Samir

    2012-01-01

    Dielectric properties of materials are defined, and the major factors that influence these properties of agricultural and food materials, namely, frequency of the applied radiofrequency or microwave electric fields, and water content, temperature, and density of the materials, are discussed on the basis of fundamental concepts. The dependence of measured dielectric properties on these factors is illustrated graphically and discussed for a number of agricultural and food products, including examples of grain, peanuts, fruit, eggs, fresh chicken meat, whey protein gel, and a macaroni and cheese preparation. General observations are provided on the nature of the variation of the dielectric properties with the major variables.

  18. Influence of Superhydrophobic Properties on Deicing

    NASA Astrophysics Data System (ADS)

    Nazhipkyzy, M.; Mansurov, Z. A.; Amirfazli, A.; Esbosin, A.; Temirgaliyeva, T. S.; Lesbayev, B. T.; Aliyev, E. T.; Prikhodko, N. G.

    2016-11-01

    Nowadays the creation of anti-icing, or deicing, surfaces is one of the most important problems, as such surfaces are widely used in aeronautics, wind turbines, and telecommunication antennas. In this paper, we focus mainly on reducing the ice adhesion forces and easy ice removal, once ice has formed. Removal of a liquid from a surface can be provided by modification of the surface wettability by means of applying superhydrophobic coatings. Such coatings are water-resistant, i.e., are characterized by low water adhesion forces. To study the impact of superhydrophobic coatings, tests were performed on the surface of a wing in a wind tunnel. By spraying Teflon and polyphenylene sulfide (PPS) on the wing, we obtained a superhydrophobic film. This film has a structure that provides superhydrophobic properties, so that the wetting angle is above 140°. A comparison of the resulting surface with a clean Teflon one shows that adhesion of the Teflon + PPS mixture to an aluminum surface is five times higher. We also investigate the degree of ice formation on the surfaces of simple and superhydrophobic aircraft wings at a temperature of -18°C. It was shown that ice was formed on a simple wing within 40 s and on a superhydrophobic wing within 25 s. When the simple wing with a mass of 23 g was inserted into the wind tunnel, its mass reached 50 g, and for a superhydrophobic wing with a mass of 26 g the latter reached 42 g. The sample of the airfoil wing we prepared has a low adhesion, which helps in easy ice removal.

  19. Consideration of coastal carbonate chemistry in understanding biological calcification

    NASA Astrophysics Data System (ADS)

    Fassbender, Andrea J.; Sabine, Christopher L.; Feifel, Kirsten M.

    2016-05-01

    Correlations between aragonite saturation state (ΩAr) and calcification have been identified in many laboratory manipulation experiments aiming to assess biological responses to ocean acidification (OA). These relationships have been used with projections of ΩAr under continued OA to evaluate potential impacts on marine calcifiers. Recent work suggests, however, that calcification in some species may be controlled by the ratio of bicarbonate to hydrogen ion, or the substrate-to-inhibitor ratio (SIR), rather than ΩAr. SIR and ΩAr are not always positively correlated in the natural environment, which means that ΩAr can be a poor indicator of the calcifying environment when ΩAr->1. Highly variable carbonate chemistry in the coastal zone challenges our ability to monitor fluctuations in ΩAr, SIR, and the ΩAr-SIR relationship making it difficult to assess biological OA exposures and vulnerability. Careful consideration of natural variability throughout ocean environments is required to accurately determine the influence of OA on biological calcification.

  20. How divergence mechanisms influence disassortative mixing property in biology

    NASA Astrophysics Data System (ADS)

    Xu, Chunsui; Liu, Zengrong; Wang, Ruiqi

    2010-02-01

    The duplication-divergence mechanism of network growth has been widely investigated, especially in gene and protein networks. Both the duplication and divergence have a key role in biological network evolution. However, the relative roles of these mechanisms in the influence of disassortative property in protein interaction networks remain to be clarified. It has been shown that duplication can indeed make protein networks evolve towards disassortative networks. To make the relationship between the disassortative property and the duplication-divergence mechanism more clear, we further discuss how the divergence mechanism influences the disassortative property. We tested four different divergence mechanisms, i.e., node deletion, edge deletion, edge addition, and edge rewiring to study their effects on disassortative property. Our study highlights the crucial roles of different divergence evolution mechanisms.

  1. Coral calcification in a changing ocean

    USGS Publications Warehouse

    Kuffner, Ilsa B.

    2010-01-01

    One of the goals of the Coral Reef Ecosystem Studies (CREST) project is to examine how calcification rates in reef-building corals and encrusting coralline algae are changing in response to changes in the ocean environment.

  2. Three-dimensional imaging of breast calcifications

    NASA Astrophysics Data System (ADS)

    Maidment, Andrew D. A.; Albert, Michael; Conant, Emily F.

    1998-03-01

    Approximately 50 percent of breast cancers are detected on the basis of calcifications alone. Regrettably, the presence of such calcifications is non-specific; only 30 percent of biopsies based on suspicious calcifications are malignant. We have investigated three methods (LVR) for 3D imaging and analysis of microcalcifications. Our aim is to increase specificity by more accurately distinguishing between calcifications indicative of benign and malignant breast lesions. We have demonstrated that 3D imaging of calcifications is possible using an LVR technique that includes semi-automated segmentation, correlation, and reconstruction of the calcifications. A clinical study of he LVR method is ongoing in which 2D film and digital images are compared to 3D images. The images are evaluated using a rating of 1 to 5, where 1 equals definitely benign, 5 equals definitely malignant, and a score of 3 or higher requires biopsy. To date, 3 radiologists have evaluated the images of 44 patients for which biopsy results were available. The use of 2D and 3D digital images resulted in doubling the diagnostic accuracy from 36 percent to 77 percent. Comparison to other techniques is ongoing. Additionally, a high resolution CT scanner for breast tissue specimens is under construction for comparison of the reconstructed images to a 'gold standard'.

  3. The Role of Epigenetics in Arterial Calcification

    PubMed Central

    Wu, Shan-Shan; Lin, Xiao; Yuan, Ling-Qing; Liao, Er-Yuan

    2015-01-01

    Arterial calcification is highly prevalent and correlated with cardiovascular mortality, especially in patients with ESRD or diabetes. The pathogenesis of arterial calcification is multifactorial, with both genetic and environmental factors being implicated. In recent years, several mechanisms contributing to arterial calcification have been proposed. However, these can only explain a small proportion of the variability in arterial calcification, which is a major obstacle for its prevention and management. Epigenetics has emerged as one of the most promising areas that may fill in some of the gaps in our current knowledge of the interaction between the environmental insults with gene regulation in the development of diseases. Epigenetics refers to heritable and acquired changes in gene transcription that occur independently of the DNA sequence. Well-known components of epigenetic regulation include DNA methylation, histone modifications, and microRNAs. Epigenetics research in the regulation of arterial calcification has only recently been elucidated. In this review, we will summarise recent progress in epigenetic pathways involved in arterial calcification and discuss potential therapeutic interventions based on epigenetic mechanisms. PMID:26221588

  4. A comparative study of physiologic intracranial calcifications.

    PubMed

    Abbassioun, K; Aarabi, B; Zarabi, M

    1978-04-01

    It has been the impression of clinicians that pineal calcification is infrequent in Shiraz, Iran. In order to evaluate this clinical impression 2000 consecutive skul X-rays taken at Saadi Hospital, Shiraz, Iran, were reviewed for the presence of physiologic intracranial calcifications. The incidence of these clasifications in male and female in consecutive age groups of 10 years from 0 to over 70 years of age were assessed and compared with previous reports from other countries. The average incidence of pineal calcification for those over 20 years of age was 18.29% in this study compared with 55% in the U.S.A. The incidence of calcification in the choroid plexus and the falx cerebri was also considerably less than previously reported. The literature is reviewed and the possible causes for the geographical differences in the reported frequency of physiologic intracranial calcifications is discussed. It is possible that racial and dietary factors may be significant in the variation in the incidence of pineal and other cranial calcifications noted in different countries. Within a population group, age and sex are additional factors.

  5. Treatment with pyrophosphate inhibits uremic vascular calcification.

    PubMed

    O'Neill, W Charles; Lomashvili, Koba A; Malluche, Hartmut H; Faugere, Marie-Claude; Riser, Bruce L

    2011-03-01

    Pyrophosphate, which may be deficient in advanced renal failure, is a potent inhibitor of vascular calcification. To explore its use as a potential therapeutic, we injected exogenous pyrophosphate subcutaneously or intraperitoneally in normal rats and found that their plasma pyrophosphate concentrations peaked within 15 min. There was a single exponential decay with a half-life of 33 min. The kinetics were indistinguishable between the two routes of administration or in anephric rats. The effect of daily intraperitoneal pyrophosphate injections on uremic vascular calcification was then tested in rats fed a high-phosphate diet containing adenine for 28 days to induce uremia. Although the incidence of aortic calcification varied and was not altered by pyrophosphate, the calcium content of calcified aortas was significantly reduced by 70%. Studies were repeated in uremic rats given calcitriol to produce more consistent aortic calcification and treated with sodium pyrophosphate delivered intraperitoneally in a larger volume of glucose-containing solution to prolong plasma pyrophosphate levels. This maneuver significantly reduced both the incidence and amount of calcification. Quantitative histomorphometry of bone samples after double-labeling with calcein indicated that there was no effect of pyrophosphate on the rates of bone formation or mineralization. Thus, exogenous pyrophosphate can inhibit uremic vascular calcification without producing adverse effects on bone.

  6. The impact of osteophytic and vascular calcifications on vertebral mineral density measurements in men.

    PubMed

    Orwoll, E S; Oviatt, S K; Mann, T

    1990-04-01

    To evaluate the influence of extravertebral calcification on spinal bone density determinations, we measured lumbar vertebral density in 71 hospitalized and 58 normal men using dual photon absorptiometry. The extent of vascular and osteophytic calcification was graded from lateral lumbar radiographs. Fifty-five (43%) of the subjects had identifiable osteophytes, and 86 (67%) had vascular calcifications. Despite similar ages and weights in subjects with and without ostephytes, those with osteophytes had greater spinal density (1.34 vs. 1.17 g/cm2; P less than 0.001), and there was a strong correlation between osteophyte severity and spinal density (r = 0.41; P less than 0.00001). Proximal femoral density was not different in those with and without osteophytes. The distribution of osteophytes in this population was not random, and as a result, the presence of osteophytes obscured the the relationship of bone density to age as well as the comparison of hospitalized to normal men. Vascular calcification had a minimal effect on vertebral density. In summary, osteophytic calcification exerted an important influence on the measurement of spinal bone density in men. This effect should be considered in both clinical and research applications of integral vertebral density measures.

  7. Pseudohypoparathyroidism with basal ganglia calcification

    PubMed Central

    Song, Cheng-Yuan; Zhao, Zhen-Xiang; Li, Wei; Sun, Cong-Cong; Liu, Yi-Ming

    2017-01-01

    Abstract Rationale: Parkinsonism can be secondary to many internal diseases, in some certain conditions, it seems that the clinical manifestations of parkinsonism presenting reversible. We report a case of patient with parkinsonism secondary to pseudohypoparathyroidism, who improved markedly after the supplement of serum calcium. Patient concerns and diagnoses: A 52-year-old woman with acute parkinsonism was diagnosed as pseudohypoparathyroidism after the conducting of brain computed tomography, laboratory examinations, and gene detection. The son of the patient was also examined and was diagnosed as pseudohypoparathyroidism, who had ever complained of the history of epilepsy. The clinical manifestations of parkinsonism of the patient was reevaluated after the supplement of serum calcium according to the diagnosis. Interventions and outcomes: The brain computed tomography revealed the basal ganglia calcification of the patient, accompanying by serum hypocalcemia and hyperphosphatemia. Loss of function mutation also confirmed the diagnosis. Five days after the therapy targeting at correction of serum hypocalcemia, the patient improved greatly in dyskinesia. Lessons: This study reported a patient presenting as acute reversible parkinsonism, who was finally diagnosed as pseudohypoparathyroidism. It indicated us that secondary parkinsonism should be carefully differentiated for its dramatic treatment effect. And the family history of seizures might be an indicator for the consideration of pseudohypoparathyroidism. PMID:28296742

  8. Acute Renal Infarction Secondary to Calcific Embolus from Mitral Annular Calcification

    SciTech Connect

    Bande, Dinesh; Abbara, Suhny; Kalva, Sanjeeva P.

    2011-06-15

    We report a case of a 62-year-old man who presented with right groin pain who subsequently was found to have a renal infarct secondary to calcific embolus from mitral annular calcification on CT and angiography. We briefly review the literature and discuss the importance of this entity in clinical practice.

  9. Influence of optical material properties on the perception of liquids.

    PubMed

    van Assen, Jan Jaap R; Fleming, Roland W

    2016-12-01

    In everyday life we encounter a wide range of liquids (e.g., water, custard, toothpaste) with distinctive optical appearances and viscosities. Optical properties (e.g., color, translucency) are physically independent of viscosity, but, based on experience with real liquids, we may associate specific appearances (e.g., water, caramel) with certain viscosities. Conversely, the visual system may discount optical properties, enabling "viscosity constancy" based primarily on the liquid's shape and motion. We investigated whether optical characteristics affect the perception of viscosity and other properties of liquids. We simulated pouring liquids with viscosities ranging from water to molten glass and rendered them with nine different optical characteristics. In Experiment 1, observers (a) adjusted a match stimulus until it had the same perceived viscosity as a test stimulus with different optical properties, and (b) rated six physical properties of the test stimuli (runniness, shininess, sliminess, stickiness, warmth, wetness). We tested moving and static stimuli. In Experiment 2, observers had to associate names with every liquid in the stimulus set. We find that observers' viscosity matches correlated strongly with the true viscosities and that optical properties had almost no effect. However, some ratings of liquid properties did show substantial interactions between viscosity and optical properties. Observers associate liquid names primarily with optical cues, although some materials are associated with a specific viscosity or combination of viscosity and optics. These results suggest viscosity is inferred primarily from shape and motion cues but that optical characteristics influence recognition of specific liquids and inference of other physical properties.

  10. Imaging Patterns of Intratumoral Calcification in the Abdominopelvic Cavity

    PubMed Central

    Yu, Mi Hye; Park, Hee Sun; Jung, Sung Il; Jeon, Hae Jeong

    2017-01-01

    Intratumoral calcification is one of the most noticeable of radiologic findings. It facilitates detection and provides information important for correctly diagnosing tumors. In the abdominopelvic cavity, a wide variety of tumors have calcifications with various imaging features, though the majority of such calcifications are dystrophic in nature. In this article, we classify the imaging patterns of intratumoral calcification according to number, location, and morphology. Then, we describe commonly-encountered abdominopelvic tumors containing typical calcification patterns, focusing on their differentiable characteristics using the imaging patterns of intratumoral calcification. PMID:28246512

  11. Tungsten nanoparticles influence on radiation protection properties of polymers

    NASA Astrophysics Data System (ADS)

    Gavrish, V. M.; Baranov, G. A.; Chayka, T. V.; Derbasova, N. M.; Lvov, A. V.; Matsuk, Y. M.

    2016-02-01

    In the presented article the results of the study of metal-polymer composites based on the ultra-high molecular weight polyethylene GUR 4122 with the addition of superdispersed tungsten nanopowders with 5, 10, 20, 40, and 50 mass percent content levels are given, their thermophysical, radiation-shielding, and mechanical properties are shown, and the influence of content levels of tungsten superdispersed nanopowders on these properties is analyzed. The conducted studies have shown the increase in the listed properties depending on the content level of tungsten superdispersed and nanopowders in the ultra-high molecular weight polyethylene GUR 4122. Owing to their properties, the obtained materials may be used in various fields, such as aviation, space technologies, mechanical engineering, etc.

  12. Influence of succinylation on physicochemical property of yak casein micelles.

    PubMed

    Yang, Min; Yang, Jitao; Zhang, Yuan; Zhang, Weibing

    2016-01-01

    Succinylation is a chemical-modification method that affects the physicochemical characteristics and functional properties of proteins. This study assessed the influence of succinylation on the physicochemical properties of yak casein micelles. The results revealed that surface hydrophobicity indices decreased with succinylation. Additionally, denaturation temperature and denaturation enthalpy decreased with increasing succinylation level, except at 82%. The buffering properties of yak casein micelles were affected by succinylation. It was found that chemical modification contributed to a slight shift of the buffering peak towards a lower pH value and a markedly increase of the maximum buffering values of yak casein micelles at pH 4.5-6.0 and pH < 3. Succinylation increased yak casein micellar hydration and whiteness values. The findings obtained from this study will provide the basic information on the physicochemical properties of native and succinylated yak casein micelles.

  13. Microstructural influences on the mechanical properties of solder

    SciTech Connect

    Morris, J.W. Jr.; Goldstein, J.L.F.; Mei, Z.

    1993-04-01

    Intent of this book is to review analytic methods for predicting behavior of solder joints, based on continuum mechanics. The solder is treated as a continuous, homogeneous body, or composite of such bodies, whose mechanical behavior is uniform and governed by simple constitutive equations. The microstructure of a solder joint influences its mechanical properties in 3 ways: it governs deformation and failure; common solders deform inhomogeneously; and common solders are microstructurally unstable. The variety of microstructures often found in solder joints are briefly reviewed, and some of the ways are discussed in which the microstructure influences the common types of high-temperature mechanical behavior. 25 figs, 40 refs.

  14. Idiopathic Arterial Calcification of Infancy: Case Report.

    PubMed

    Attia, Tarek Hamed; Abd Alhamed, Mohamed Maisara; Selim, Mohamed Fouad; Haggag, Mohamed Salah; Fathalla, Diaa

    2015-11-01

    Idiopathic arterial calcification of infancy is a rare autosomal recessive disease, characterized by deposition of calcium along the internal elastic membrane of arteries, accompanied by fibrous thickening of the intima which causes luminal narrowing. Here we are reporting a case of idiopathic arterial calcification of infancy in a Saudi female newborn of non-consanguineous pregnant woman who had polyhydramnios. The newborn baby had severe respiratory distress, systemic hypertension and persistent pulmonary hypertension of newborn. She was admitted to Neonatal Intensive Care Unit, where she was ventilated and proper treatment was provided. Molecular genetic testing was positive for mutations of ectonucleotide pyrophosphatase/phosphodiesterase1 gene which is reported in 80% of cases of Idiopathic arterial calcification of infancy. The baby died at about 5 month of age because of myocardial ischemia and cardiorespiratory arrest. Idiopathic Arterial Calcification of Infancy should be considered in any newborn who presented with persistent pulmonary hypertension of newborn, severe systemic hypertension and echogenic vessels on any radiological study. Calcifications of large and medium-sized arteries are important diagnostic finding.

  15. Idiopathic Arterial Calcification of Infancy: Case Report

    PubMed Central

    Attia, Tarek Hamed; Abd Alhamed, Mohamed Maisara; Selim, Mohamed Fouad; Haggag, Mohamed Salah; Fathalla, Diaa

    2015-01-01

    Idiopathic arterial calcification of infancy is a rare autosomal recessive disease, characterized by deposition of calcium along the internal elastic membrane of arteries, accompanied by fibrous thickening of the intima which causes luminal narrowing. Here we are reporting a case of idiopathic arterial calcification of infancy in a Saudi female newborn of non-consanguineous pregnant woman who had polyhydramnios. The newborn baby had severe respiratory distress, systemic hypertension and persistent pulmonary hypertension of newborn. She was admitted to Neonatal Intensive Care Unit, where she was ventilated and proper treatment was provided. Molecular genetic testing was positive for mutations of ectonucleotide pyrophosphatase/phosphodiesterase1 gene which is reported in 80% of cases of Idiopathic arterial calcification of infancy. The baby died at about 5 month of age because of myocardial ischemia and cardiorespiratory arrest. Idiopathic Arterial Calcification of Infancy should be considered in any newborn who presented with persistent pulmonary hypertension of newborn, severe systemic hypertension and echogenic vessels on any radiological study. Calcifications of large and medium-sized arteries are important diagnostic finding. PMID:27252793

  16. Influence of trace elements on dental enamel properties: A review.

    PubMed

    Qamar, Zeeshan; Haji Abdul Rahim, Zubaidah Binti; Chew, Hooi Pin; Fatima, Tayyaba

    2017-01-01

    Dental enamel, an avascular, irreparable, outermost and protective layer of the human clinical crown has a potential to withstand the physico-chemical effects and forces. These properties are being regulated by a unique association among elements occurring in the crystallites setup of human dental enamel. Calcium and phosphate are the major components (hydroxyapatite) in addition to some trace elements which have a profound effect on enamel. The current review was planned to determine the aptitude of various trace elements to substitute and their influence on human dental enamel in terms of physical and chemical properties.

  17. Influence of Laser Reconditioning on Fatigue Properties of Crankshafts

    NASA Astrophysics Data System (ADS)

    Koehler, Henry; Partes, Knut; Seefeld, Thomas; Vollertsen, Frank

    Expensive machine parts often are repaired by additive processes to limit costs and increase productivity. However, repairing marine diesel engine crankshafts for these aims is not yet approved by the classification societies since the influence on mechanical properties can neither be predicted nor has been investigated sufficiently. A method for testing the influence of laser cladding on fatigue properties of marine crankshafts is presented. Tests on flat specimen indicated a drop in fatigue strength in consequence of laser cladding. The number of bearable load cycles of cladded crankshaft segments at 100% fatigue strength calculated according to CIMAC standards dropped. Origins of cracks could be traced back to cladded areas as well as to crankshaft fillets.

  18. Dark calcification and the daily rhythm of calcification in the scleractinian coral, Galaxea fascicularis

    NASA Astrophysics Data System (ADS)

    Al-Horani, F. A.; Tambutté, É.; Allemand, D.

    2007-09-01

    The rate of calcification in the scleractinian coral Galaxea fascicularis was followed during the daytime using 45Ca tracer. The coral began the day with a low calcification rate, which increased over time to a maximum in the afternoon. Since the experiments were carried out under a fixed light intensity, these results suggest that an intrinsic rhythm exists in the coral such that the calcification rate is regulated during the daytime. When corals were incubated for an extended period in the dark, the calcification rate was constant for the first 4 h of incubation and then declined, until after one day of dark incubation, calcification ceased, possibly as a result of the depletion of coral energy reserves. The addition of glucose and Artemia reduced the dark calcification rate for the short duration of the experiment, indicating an expenditure of oxygen in respiration. Artificial hypoxia reduced the rate of dark calcification to about 25% compared to aerated coral samples. It is suggested that G. fascicularis obtains its oxygen needs from the surrounding seawater during the nighttime, whereas during the day time the coral exports oxygen to the seawater.

  19. High-Dose Menaquinone-7 Supplementation Reduces Cardiovascular Calcification in a Murine Model of Extraosseous Calcification.

    PubMed

    Scheiber, Daniel; Veulemans, Verena; Horn, Patrick; Chatrou, Martijn L; Potthoff, Sebastian A; Kelm, Malte; Schurgers, Leon J; Westenfeld, Ralf

    2015-08-18

    Cardiovascular calcification is prevalent in the aging population and in patients with chronic kidney disease (CKD) and diabetes mellitus, giving rise to substantial morbidity and mortality. Vitamin K-dependent matrix Gla-protein (MGP) is an important inhibitor of calcification. The aim of this study was to evaluate the impact of high-dose menaquinone-7 (MK-7) supplementation (100 µg/g diet) on the development of extraosseous calcification in a murine model. Calcification was induced by 5/6 nephrectomy combined with high phosphate diet in rats. Sham operated animals served as controls. Animals received high or low MK-7 diets for 12 weeks. We assessed vital parameters, serum chemistry, creatinine clearance, and cardiac function. CKD provoked increased aortic (1.3 fold; p < 0.05) and myocardial (2.4 fold; p < 0.05) calcification in line with increased alkaline phosphatase levels (2.2 fold; p < 0.01). MK-7 supplementation inhibited cardiovascular calcification and decreased aortic alkaline phosphatase tissue concentrations. Furthermore, MK-7 supplementation increased aortic MGP messenger ribonucleic acid (mRNA) expression (10-fold; p < 0.05). CKD-induced arterial hypertension with secondary myocardial hypertrophy and increased elastic fiber breaking points in the arterial tunica media did not change with MK-7 supplementation. Our results show that high-dose MK-7 supplementation inhibits the development of cardiovascular calcification. The protective effect of MK-7 may be related to the inhibition of secondary mineralization of damaged vascular structures.

  20. High-Dose Menaquinone-7 Supplementation Reduces Cardiovascular Calcification in a Murine Model of Extraosseous Calcification

    PubMed Central

    Scheiber, Daniel; Veulemans, Verena; Horn, Patrick; Chatrou, Martijn L.; Potthoff, Sebastian A.; Kelm, Malte; Schurgers, Leon J.; Westenfeld, Ralf

    2015-01-01

    Cardiovascular calcification is prevalent in the aging population and in patients with chronic kidney disease (CKD) and diabetes mellitus, giving rise to substantial morbidity and mortality. Vitamin K-dependent matrix Gla-protein (MGP) is an important inhibitor of calcification. The aim of this study was to evaluate the impact of high-dose menaquinone-7 (MK-7) supplementation (100 µg/g diet) on the development of extraosseous calcification in a murine model. Calcification was induced by 5/6 nephrectomy combined with high phosphate diet in rats. Sham operated animals served as controls. Animals received high or low MK-7 diets for 12 weeks. We assessed vital parameters, serum chemistry, creatinine clearance, and cardiac function. CKD provoked increased aortic (1.3 fold; p < 0.05) and myocardial (2.4 fold; p < 0.05) calcification in line with increased alkaline phosphatase levels (2.2 fold; p < 0.01). MK-7 supplementation inhibited cardiovascular calcification and decreased aortic alkaline phosphatase tissue concentrations. Furthermore, MK-7 supplementation increased aortic MGP messenger ribonucleic acid (mRNA) expression (10-fold; p < 0.05). CKD-induced arterial hypertension with secondary myocardial hypertrophy and increased elastic fiber breaking points in the arterial tunica media did not change with MK-7 supplementation. Our results show that high-dose MK-7 supplementation inhibits the development of cardiovascular calcification. The protective effect of MK-7 may be related to the inhibition of secondary mineralization of damaged vascular structures. PMID:26295257

  1. Regulatory Circuits Controlling Vascular Cell Calcification

    PubMed Central

    Sallam, Tamer; Cheng, Henry; Demer, Linda L.; Tintut, Yin

    2013-01-01

    Vascular calcification is a common feature of chronic kidney disease, cardiovascular disease, and aging. Such abnormal calcium deposition occurs in medial and/or intimal layers of blood vessels as well as in cardiac valves. Once considered a passive and inconsequential finding, the presence of calcium deposits in the vasculature is widely accepted as a predictor of increased morbidity and mortality. Recognition of the importance of vascular calcification in health is driving research into mechanisms that govern its development, progression, and regression. Diverse, but highly interconnected factors, have been implicated, including disturbances in lipid metabolism, oxidative stress, inflammatory cytokines, and mineral and hormonal balances, which can lead to formation of osteoblast-like cells in the artery wall. A tight balance of procalcific and anticalcific regulators dictates the extent of disease. In this review, we focus on the main regulatory circuits modulating vascular cell calcification. PMID:23269436

  2. Genetics Home Reference: generalized arterial calcification of infancy

    MedlinePlus

    ... Home Health Conditions GACI generalized arterial calcification of infancy Enable Javascript to view the expand/collapse boxes. ... All Close All Description Generalized arterial calcification of infancy ( GACI ) is a disorder affecting the circulatory system ...

  3. Polyethylene glycol-grafted bovine pericardium: a novel hybrid tissue resistant to calcification.

    PubMed

    Vasudev, S C; Chandy, T

    1999-02-01

    Calcification is a frequent cause of the clinical failure of bioprosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium (GATBP). An investigation was made of the grafting of different molecular weight polyethylene glycol (PEG 600, 1500, 4000 and 6000) via glutaraldehyde (GA) linkages to bovine pericardium (BP) and of their stability and calcification. The process of the calcification profile was studied by in vitro experiments via incubating pericardial samples in a metastable solution of calcium phosphate. Calcification of bovine pericardium grafted with PEG 6000 was significantly decreased compared to low molecular weight PEG grafts or Sodium dodecyl sulphate- (SDS) and GA-treated tissues. The mechanical properties of these modified tissues after enzyme (Trypsin) digestion and calcification were investigated. The biocompatibility aspects of grafted tissues were also established by monitoring the platelet adhesion, octane contact angle and water of hydration. PEG 6000-grafted tissues retained the maximum strength in trypsin buffer and calcium phosphate solutions. Scanning electron micrographs revealed that the PEG-grafted bovine pericardium had substantially inhibited the platelet-surface attachment and their spreading. It is conceivable that high molecular weight polyethylene glycol-grafted pericardium (a hybrid tissue) may be a suitable calcium-resistant material for developing prosthetic valves due to their stability and biocompatibility.

  4. Calcific band keratopathy in an alpaca.

    PubMed

    Pucket, Jonathan D; Boileau, Melanie J; Sula, Mee Ja M

    2014-07-01

    A 4-year-old female Suri alpaca was presented for evaluation of acute onset weakness, lethargy, and recent development of opacities in both eyes. On ophthalmic examination, bilaterally symmetrical corneal opacities were noted along the interpalpebral fissures with a few corneal blood vessels intermingled. A presumed diagnosis of calcific band keratopathy was made based on location and appearance. The patient was euthanized a short while after diagnosis due to reasons unrelated to the eyes and histologic examination of the corneas revealed subepithelial calcium and vascularization, consistent with calcific band keratopathy. This case report is the first to document this ocular condition in an alpaca.

  5. Species-specific responses to climate change and community composition determine future calcification rates of Florida Keys reefs.

    PubMed

    Okazaki, Remy R; Towle, Erica K; van Hooidonk, Ruben; Mor, Carolina; Winter, Rivah N; Piggot, Alan M; Cunning, Ross; Baker, Andrew C; Klaus, James S; Swart, Peter K; Langdon, Chris

    2017-03-01

    Anthropogenic climate change compromises reef growth as a result of increasing temperatures and ocean acidification. Scleractinian corals vary in their sensitivity to these variables, suggesting species composition will influence how reef communities respond to future climate change. Because data are lacking for many species, most studies that model future reef growth rely on uniform scleractinian calcification sensitivities to temperature and ocean acidification. To address this knowledge gap, calcification of twelve common and understudied Caribbean coral species was measured for two months under crossed temperatures (27, 30.3 °C) and CO2 partial pressures (pCO2 ) (400, 900, 1300 μatm). Mixed-effects models of calcification for each species were then used to project community-level scleractinian calcification using Florida Keys reef composition data and IPCC AR5 ensemble climate model data. Three of the four most abundant species, Orbicella faveolata, Montastraea cavernosa, and Porites astreoides, had negative calcification responses to both elevated temperature and pCO2 . In the business-as-usual CO2 emissions scenario, reefs with high abundances of these species had projected end-of-century declines in scleractinian calcification of >50% relative to present-day rates. Siderastrea siderea, the other most common species, was insensitive to both temperature and pCO2 within the levels tested here. Reefs dominated by this species had the most stable end-of-century growth. Under more optimistic scenarios of reduced CO2 emissions, calcification rates throughout the Florida Keys declined <20% by 2100. Under the most extreme emissions scenario, projected declines were highly variable among reefs, ranging 10-100%. Without considering bleaching, reef growth will likely decline on most reefs, especially where resistant species like S. siderea are not already dominant. This study demonstrates how species composition influences reef community responses to climate change

  6. Linking calcification by exotic snails to stream inorganic carbon cycling.

    PubMed

    Hotchkiss, Erin R; Hall, Robert O

    2010-05-01

    Biotic calcification is rarely considered in freshwater C budgets, despite calculations suggesting that calcifying animals can alter inorganic C cycling. Most studies that have quantified biocalcification in aquatic ecosystems have not directly linked CO(2) fluxes from biocalcification with whole-ecosystem rates of inorganic C cycling. The freshwater snail, Melanoides tuberculata, has achieved a high abundance and 37.4 g biomass m(-2) after invading Kelly Warm Springs in Grand Teton National Park. This high biomass suggests that introduced populations of Melanoides may alter ecosystem processes. We measured Melanoides growth rates and biomass to calculate the production of biomass, shell mass, and CO(2). We compared Melanoides biomass and inorganic C production with ecosystem C pools and fluxes, as well as with published rates of CO(2) production by other calcifying organisms. Melanoides calcification in Kelly Warm Springs produced 12.1 mmol CO(2) m(-2) day(-1) during summer months. We measured high rates of gross primary productivity and respiration in Kelly Warm Springs (-378 and 533 mmol CO(2) m(-2) day(-1), respectively); CO(2) produced from biocalcification increased net CO(2) production in Kelly Warm Springs from 155 to 167 mmol CO(2) m(-2) day(-1). This rate of CO(2) production via biocalcification is within the published range of calcification by animals. But these CO(2) fluxes are small when compared to ecosystem C fluxes from stream metabolism. The influence of animals is relative to ecosystem processes, and should always be compared with ecosystem fluxes to quantify the importance of a specific animal in its environment.

  7. [Vascular Calcification - Pathological Mechanism and Clinical Application - . Vascular calcification in chronic kidney disease-mineral and bone disorder (CKD-MBD)].

    PubMed

    Omata, Momoyo; Fukagawa, Masafumi; Kakuta, Takatoshi

    2015-05-01

    Chronic kidney disease-mineral and bone disorder (CKD-MBD), is sequential pathophysiology that starts in the very early stages of CKD. Three major aspects of CKD-MBD are laboratory abnormalities, bone abnormalities and vascular calcification. In dialysis patients, the prevalence of death due to cardiovascular disease accounts for more than 40% of all-cause mortality. Therefore, arteriosclerosis with vascular calcification may be an important pathophysiological mechanism in the development of cardiovascular disease. Vascular calcification is known to be an important risk factor influencing mortality in CKD patients. A number of studies have suggested a close association between serum FGF23 concentration and the risks of mortality, cardiovascular disease vascular calcification as well as CKD progression. Renal insufficiency leads to decline in klotho level and impaired phosphate excretion. However serum phosphate levels are maintained in the normal range by up regulation of FGF23 and PTH in early CKD stage. Early treatment intervention is necessary to improve the prognosis of the CKD patient.

  8. An investigation of aerosol optical properties: Atmospheric implications and influences

    NASA Astrophysics Data System (ADS)

    Penaloza-Murillo, Marcos A.

    An experimental, observational, and theoretical investigation of aerosol optical properties has been made in this work to study their implications and influences on the atmosphere. In the laboratory the scientific and instrumental methodology consisted of three parts, namely, aerosol generation, optical and mass concentration measurements, and computational calculations. In particular the optical properties of ammonium sulfate and caffeine aerosol were derived from measurements made with a transmissometer cell-reciprocal- integrating nephelometer (TCRIN), equipped with a laser beam at 632.8 nm, and by applying a Mie theory computer code The aerosol generators, optical equipment and calibration procedures were reviewed. The aerosol shape and size distribution were studied by means of scanning electron microscopy and the Gumprecht- Sliepcevich/Lipofsky-Green extinction-sedimentation method. In particular the spherical and cylindrical shape were considered. During this investigation, an alternative method for obtaining the optical properties of monodisperse spherical non-absorbing aerosol using a cell-transmissometer, which is based on a linearisation of the Lambert-Beer law, was found. In addition, adapting the TCRIN to electrooptical aerosol studies, the optical properties of a circular-cylindrical aerosol of caffeine were undertaken under the condition of random orientation in relation with the laser beam, and perpendicular orientation to it. A theoretical study was conducted to assess the sensitivity of aerosol to a change of shape under different polarisation modes. The aerosol optical properties, obtained previously in the laboratory, were then used to simulate the direct radiative forcing. The calculations and results were obtained by applying a one- dimensional energy-balance box model. The influence of atmospheric aerosol on the sky brightness due to a total solar eclipse was studied using the photometric and meteorological observations made during the

  9. Influence of Delhi Pollution on Aerosol Properties Over Greater Noida

    NASA Astrophysics Data System (ADS)

    Sharma, M.; Singh, R. P.; Kumar, R.

    2015-12-01

    Influence of Delhi Pollution on Aerosol Properties over Greater NoidaManish Sharma1, Ramesh P. Singh2 and Rajesh Kumar3 1Research and Technology Development Centre, Sharda University, Greater Noida, India. 2School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange 92866, USA 3School of Basic Sciences and Research, Sharda University, Greater Noida, India. Delhi capital of India is highly polluted during winter and summer seasons. Due to dominant westerly winds the air mass influence its neighboring city Greater Noida which is located 60 km south east of Delhi. Detailed analysis of multi satellite data and ground observations have been carried out during 2001-2015. The ground observation and satellite data show dynamic aerosol optical parameters over Greater Noida. During winter and summer seasons, dominant westerly wind outflow pollutants of Delhi that mix with the local anthropogenic emissions of Greater Noida influencing aerosol properties at different pressure levels. The characteristics of trace gases and aerosol parameters over Delhi and Greater Noida will be presented. The air quality is severely affected from the outflow of pollutants from Delhi which is threat to people living in the area. Due to dominant winds the air mass further transported towards eastern parts of Indo-Gangetic plains affecting weather conditions of the major cities.

  10. Influence of coal properties on NO{sub x} emissions

    SciTech Connect

    Conn, S.K.; Bond, R.A.; Thompson, A.W.; Allen, J.W.

    1995-12-31

    Fundamental coal characterization work has indicated the particular properties which influence the performance of coals in Low-NO{sub x} combustion systems. These properties influence NO{sub x} emissions as well as unburned carbon levels, slagging and fouling tendencies. The performance of a 265 MW boiler retrofitted with a flame attachment nozzle burner Low-NO{sub x} system is discussed in terms of these basic coal properties. Owensboro Municipal Utilities` Elmer Smith Station is comprised of one 151 MW{sub E} cyclone-fired and one 265 MW{sub E} tangentially-fired pulverized coal burning generating unit. It is located in Owensboro, Kentucky on the Ohio River, and provides electric power to the city of Owensboro as well as a neighboring utility. The station historically burn approximately 1.1 million tons of 6lb SO{sub 2}/mmBTU coal from the surrounding western Kentucky coal fields. A typical proximate analysis for this fuel is shown.

  11. Influence of surfactants on diesel water shedding properties

    SciTech Connect

    McCarthy, K.J.; O`Brien, T.J.; Weers, J.J.

    1994-10-01

    The properties of emulsions formed when water contacts low sulfur diesel fuel supplemented with indigenous surfactants or chemical additives were studied. Small amounts of the additives were found to have dramatic effects on the stabilization or breaking of the emulsions formed during ASTM D-1094 testing. Dynamic interfacial tension measurements were also recorded to determine the influence of the surfactants on the interfacial film surrounding the water droplets in the emulsions. The results of both the ASTM test and the interfacial tension measurements were compared. 18 refs., 19 figs.

  12. Change of solar cell element properties influenced by adsorbed atoms

    NASA Astrophysics Data System (ADS)

    Livshits, A. I.; Romanovskij, Y. A.; Zavilopulo, A. N.; Zhukov, A. I.; Snegurskij, A. V.

    A series of experimental studies on the influence of alkali and alkaline-earth metal films on electro-physical properties of solar elements used for spacecraft energy supply was carried out. Metal films of different thicknesses were deposited using an effusion source, the mass of the film was calculated using measured atomic beam density. The Mg film thickness was determined by means of microscopic technique. The dynamics of current-to-voltage characteristic variation was studied for different film thickness and chemical composition in vacuum and in oxygen atmosphere.

  13. Preexisting venous calcification prior to dialysis vascular access surgery.

    PubMed

    Lee, Timmy; Safdar, Nida; Mistry, Meenakshi J; Wang, Yang; Chauhan, Vibha; Campos, Begoña; Munda, Rino; Cornea, Virgilius; Roy-Chaudhury, Prabir

    2012-01-01

    Vascular calcification is present in arterial vessels used for dialysis vascular access creation prior to surgical creation. Calcification in the veins used to create a new vascular access has not previously been documented. The objective of this study was to describe the prevalence of venous calcification in samples collected at the time of vascular access creation. Sixty-seven vein samples were studied. A von Kossa stain was performed to quantify calcification. A semi-quantitative scoring system from 0 to 4+ was used to quantify the percentage positive area for calcification as a fraction of total area (0: 0; 1+: 1-10%; 2+: 11-25%; 3+: 26-50%; 4+: >50% positive). Twenty-two of 67 (33%) samples showed evidence of venous calcification. Histologic examination showed varying degrees of calcification within each cell layer. Among the subset of patients with calcification, 4/22 (18%), 19/22 (86%), 22/22 (100%), and 7/22 (32%) had calcification present within the endothelium, intima, media, and adventitia, respectively. The mean semi-quantitative scores of the 22 samples with calcification were 0.18 ± 0.08, 1.2 ± 0.14, 1.6 ± 0.13, and 0.36 ± 0.12 for the endothelium, intima, media, and adventitia, respectively. Our results demonstrate that vascular calcification is present within veins used to create new dialysis vascular access, and located predominately within the neointimal and medial layers.

  14. The Influence of Fuelbed Physical Properties on Biomass Burning Emissions

    NASA Astrophysics Data System (ADS)

    Urbanski, S. P.; Lincoln, E.; Baker, S. P.; Richardson, M.

    2014-12-01

    Emissions from biomass fires can significantly degrade regional air quality and therefore are of major concern to air regulators and land managers in the U.S. and Canada. Accurately estimating emissions from different fire types in various ecosystems is crucial to predicting and mitigating the impact of fires on air quality. The physical properties of ecosystems' fuelbeds can heavily influence the combustion processes (e.g. flaming or smoldering) and the resultant emissions. However, despite recent progress in characterizing the composition of biomass smoke, significant knowledge gaps remain regarding the linkage between basic fuelbed physical properties and emissions. In laboratory experiments we examined the effects of fuelbed properties on combustion efficiency (CE) and emissions for an important fuel component of temperate and boreal forests - conifer needles. The bulk density (BD), depth (DZ), and moisture content (MC) of Ponderosa Pine needle fuelbeds were manipulated in 75 burns for which gas and particle emissions were measured. We found CE was negatively correlated with BD, DZ and MC and that the emission factors of species associated with smoldering combustion processes (CO, CH4, particles) were positively correlated with these fuelbed properties. The study indicates the physical properties of conifer needle fuelbeds have a significant effect on CE and hence emissions. However, many of the emission models used to predict and manage smoke impacts on air quality assume conifer litter burns by flaming combustion with a high CE and correspondingly low emissions of CO, CH4, particles, and organic compounds. Our results suggest emission models underestimate emissions from fires involving a large component of conifer needles. Additionally, our findings indicate that laboratory studies of emissions should carefully control fuelbed physical properties to avoid confounding effects that may obscure the effects being tested and lead to erroneous interpretations.

  15. Triglycidylamine Cross-linking Combined with Ethanol Inhibits Bioprosthetic Heart Valve Calcification

    PubMed Central

    Connolly, Jeanne M.; Bakay, Marina A.; Alferiev, Ivan S.; Gorman, Robert C.; Gorman, Joseph H.; Kruth, Howard S.; Ashworth, Paul E.; Kutty, Jaishankar K.; Schoen, Frederick J.; Bianco, Richard W.; Levy, Robert J.

    2012-01-01

    Background One of the most important factors responsible for the calcific failure of bioprosthetic heart valves is glutaraldehyde cross-linking. Ethanol (EtOH) incubation after glutaraldehyde cross-linking has previously been reported to confer anti-calcification efficacy for bioprostheses. The present studies investigated the anticalcification efficacy in vivo of the novel cross-linking agent, triglycidyl amine (TGA), with or without EtOH incubation, in comparison to glutaraldehyde. Methods TGA cross-linking (+/− EtOH) was used to prepare porcine aortic valves for both rat subdermal implants and sheep mitral valve replacements, for comparisons with glutaraldehyde-fixed controls. Thermal denaturation temperature (Ts), an index of cross-linking, cholesterol extraction, and hydrodynamic properties were quantified. Explant endpoints included quantitative and morphologic assessment of calcification. Results Ts after TGA were intermediate between unfixed and glutaraldehyde-fixed. EtOH incubation resulted in almost complete extraction of cholesterol from TGA or glutaraldehyde-fixed cusps. Rat subdermal explants (90days) demonstrated that TGA-EtOH resulted in a significantly greater level of inhibition of calcification than other conditions. Thus, TGA-ethanol stent mounted porcine aortic valve bioprostheses were fabricated for comparisons with glutaraldehyde-pretreated controls. In hydrodynamic studies, TGA-EtOH bioprostheses had lower pressure gradients than glutaraldehyde-fixed. TGA-ethanol bioprostheses used as mitral valve replacements in juvenile sheep (150 days) demonstrated significantly lower calcium levels in both explanted porcine aortic cusp and aortic wall samples compared to glutaraldehyde-fixed controls. However, TGA-EtOH sheep explants also demonstrated isolated calcific nodules and intracuspal hematomas. Conclusions TGA-EtOH pretreatment of porcine aortic valves confers significant calcification resistance in both rat subdermal and sheep circulatory

  16. Adipocyte induced arterial calcification is prevented with sodium thiosulfate

    SciTech Connect

    Chen, Neal X.; O’Neill, Kalisha; Akl, Nader Kassis; Moe, Sharon M.

    2014-06-20

    Highlights: • High phosphorus can induce calcification of adipocytes, even when fully differentiated. • Adipocytes can induce vascular calcification in an autocrine manner. • Sodium thiosulfate inhibits adipocyte calcification. - Abstract: Background: Calcification can occur in fat in multiple clinical conditions including in the dermis, breasts and in the abdomen in calciphylaxis. All of these are more common in patients with advanced kidney disease. Clinically, hyperphosphatemia and obesity are risk factors. Thus we tested the hypothesis that adipocytes can calcify in the presence of elevated phosphorus and/or that adipocytes exposed to phosphorus can induce vascular smooth muscle cell (VSMC) calcification. Methods: 3T3-L1 preadipocytes were induced into mature adipocytes and then treated with media containing high phosphorus. Calcification was assessed biochemically and PCR performed to determine the expression of genes for osteoblast and adipocyte differentiation. Adipocytes were also co-cultured with bovine VSMC to determine paracrine effects, and the efficacy of sodium thiosulfate was determined. Results: The results demonstrated that high phosphorus induced the calcification of differentiated adipocytes with increased expression of osteopontin, the osteoblast transcription factor Runx2 and decreased expression of adipocyte transcription factors peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding protein α (CEBPα), indicating that high phosphorus led to a phenotypic switch of adipocytes to an osteoblast like phenotype. Sodium thiosulfate, dose dependently decreased adipocyte calcification and inhibited adipocyte induced increase of VSMC calcification. Co-culture studies demonstrated that adipocytes facilitated VSMC calcification partially mediated by changes of secretion of leptin and vascular endothelial growth factor (VEGF) from adipocytes. Conclusion: High phosphorus induced calcification of mature adipocytes, and

  17. Soil physical properties influence "black truffle" fructification in plantations.

    PubMed

    Alonso Ponce, Rafael; Ágreda, Teresa; Águeda, Beatriz; Aldea, Jorge; Martínez-Peña, Fernando; Modrego, María Pilar

    2014-04-01

    Although the important effects of pH and carbonate content of soils on "black truffle" (Tuber melanosporum) production are well known, we poorly understand the influence of soil physical properties. This study focuses on physical soil characteristics that drive successful production of black truffles in plantations. Seventy-eight Quercus ilex ssp. ballota plantations older than 10 years were studied in the province of Teruel (eastern Spain). Soil samples were analyzed for various edaphic characteristics and to locate T. melanosporum ectomycorrhizae. The influence of cultivation practices, climatic features, and soil properties on sporocarp production was assessed using multivariate analyses. Low contents of fine earth and silt and high levels of bulk density, clay content, and water-holding capacity appear to promote fructification. Watering is also highly positive for truffle fructification. We develop and discuss a logistic model to predict the probability of truffle fructification in field sites under consideration for truffle plantation establishment. The balance between water availability and aeration plays a crucial role in achieving success in black truffle plantations.

  18. New treatments using alginate in order to reduce the calcification of bovine bioprosthetic heart valve tissue.

    PubMed

    Shanthi, C; Rao, K P

    1997-01-01

    Calcification limits the functional lifetime of cardiac valve substitutes fabricated from glutaraldehyde preserved bovine pericardium. Host factors, mainly younger age, and implant factors, mainly glutaraldehyde cross-linking, are implicated in the calcification process. Glutaraldehyde cross-linking is believed to activate the potential sites in the tissues for biocalcification. In the present work, we investigated the possibility of using alginate azide (AA) instead of glutaraldehyde for the preservation of pericardial tissues in order to enhance the durability of bioprosthetic heart valves. Grafting with poly(GMA-BA) copolymer to the alginate azide cross-linked pericardial (AACPC) tissue was carried out to obtain better stability, strength, and anticalcification properties. The strength property and thermal stability of the AA cross-linked tissues were studied. Calcification studies in rat subdermal models reveal that AA cross-linking reduces the calcification to negligible levels. After 30 days implantation, the calcium content was found to be 10.4 +/- 1.2 and 6.1 +/- 0.3 micrograms mg-1 for untreated AACPC and polymer grafted AACPC, respectively, compared to a value of 100 +/- 1.2 micrograms mg-1 calcium recorded for control glutaraldehyde cross-linked pericardial (GCPC) tissues.

  19. Apparent Optical Properties in Waters Influenced by the Mississippi River

    NASA Technical Reports Server (NTRS)

    D'Sa, E.; Miller, R. L.; McKee, B. A.; Trzaska, R.

    2002-01-01

    In-water downwelling irradiance (E(sub d)) and upwelling radiance (L(sub u)) were measured in coastal waters influenced by the Mississippi River at wavelengths corresponding to SeaWiFS spectral bands in April of 2000. Results of derived apparent optical properties (AOP's) such as spectral diffise attenuation coefficient for downwelling irradiance (K(sub d)) suggest that they are mainly influenced by phytoplankton chlorophyll. Large variations in chlorophyll concentrations (0.2 to greater than 10 mg per cubic meters) correspond to variations in K(sub d) at 443 nm ranging from about 0.1 to greater than 1.5 per meter. Attenuation values at 443 nm generally peaked (or were minimal at 555 nm) at depths where chlorophyll concentrations were high. Above water remote sensing reflectance R(sub rs) (443) derived from E(sub d) and L(sub u) shows good agreement to surface chlorophyll. Ratios of remote sensing reflectance, R(sub rs)(443/R(sub rs)(555)versus chlorophyll suggests a potential for obtaining a suitable bio-optical algorithm for the region influenced by the Mississippi River.

  20. Calcification by Reef-Building Sclerobionts

    PubMed Central

    Mallela, Jennie

    2013-01-01

    It is widely accepted that deteriorating water quality associated with increased sediment stress has reduced calcification rates on coral reefs. However, there is limited information regarding the growth and development of reef building organisms, aside from the corals themselves. This study investigated encruster calcification on five fore-reefs in Tobago subjected to a range of sedimentation rates (1.2 to 15.9 mg cm−2 d−1). Experimental substrates were used to assess rates of calcification in sclerobionts (e.g. crustose coralline algae, bryozoans and barnacles) across key reef microhabitats: cryptic (low-light), exposed (open-horizontal) and vertical topographic settings. Sedimentation negatively impacted calcification by photosynthesising crustose coralline algae in exposed microhabitats and encrusting foram cover (%) in exposed and cryptic substrates. Heterotrophs were not affected by sedimentation. Fore-reef, turbid water encruster assemblages calcified at a mean rate of 757 (SD ±317) g m−2 y−1. Different microhabitats were characterised by distinct calcareous encruster assemblages with different rates of calcification. Taxa with rapid lateral growth dominated areal cover but were not responsible for the majority of CaCO3 production. Cryptobiont assemblages were composed of a suite of calcifying taxa which included sciaphilic cheilostome bryozoans and suspension feeding barnacles. These calcified at mean rates of 20.1 (SD ±27) and 4.0 (SD ±3.6) g m−2 y−1 respectively. Encruster cover (%) on exposed and vertical substrates was dominated by crustose coralline algae which calcified at rates of 105.3 (SD ±67.7) g m−2 y−1 and 56.3 (SD ±8.3) g m−2 y−1 respectively. Globally, encrusting organisms contribute significant amounts of carbonate to the reef framework. These results provide experimental evidence that calcification rates, and the importance of different encrusting organisms, vary significantly according to topography and sediment

  1. Factors That Influence the Extensional Rheological Property of Saliva

    PubMed Central

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva. PMID:26305698

  2. Factors That Influence the Extensional Rheological Property of Saliva.

    PubMed

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva.

  3. Gamma irradiation influence on physical properties of milk proteins

    NASA Astrophysics Data System (ADS)

    Cieśla, K.; Salmieri, S.; Lacroix, M.; Tien, C. Le

    2004-09-01

    Gamma irradiation was found to be an effective method for the improvement of both barrier and mechanical properties of the edible films and coatings based on calcium and sodium caseinates alone or combined with some globular proteins. Our current studies concern gamma irradiation influence on the physical properties of calcium caseinate-whey protein isolate-glycerol (1:1:1) solutions and gels, used for films preparation. Irradiation of solutions was carried out with Co-60 gamma rays applying 0 and 32 kGy dose. The increase in viscosity of solutions was found after irradiation connected to induced crosslinking. Lower viscosity values were detected, however, after heating of the solutions irradiated with a 32 kGy dose than after heating of the non-irradiated ones regarding differences in the structure of gels and resulting in different temperature-viscosity curves that were recorded for the irradiated and the non-irradiated samples during heating and cooling. Creation of less stiff but better ordered gels after irradiation arises probably from reorganisation of aperiodic helical phase and β-sheets, in particular from increase of β-strands, detected by FTIR. Films obtained from these gels are characterised by improved barrier properties and mechanical resistance and are more rigid than those prepared from the non-irradiated gels. The route of gel creation was investigated for the control and the irradiated samples during heating and the subsequent cooling.

  4. Influence of Grain Boundary Properties and Orientation on Void Nucleation

    SciTech Connect

    Fensin, Saryu Jindal

    2016-03-01

    For ductile metals, dynamic fracture during shock loading is thought to occur through void nucleation, growth, and then coalescence that leads to material failure. Particularly for high purity metals, it has been observed by numerous investigators that, under incipient spall conditions, voids appear to heterogeneously nucleate at some grain boundaries, but not others. Several factors can affect the void nucleation stress at a grain boundary, such as grain boundary structure, orientation with respect to the loading direction, energy and excess volume, in addition to its interactions with dislocations. In this work, we focus on the influence of loading direction with respect to the grain boundary plane and grain boundary properties such as energy and excess volume on the stress required for void nucleation of a grain boundary, in copper from moleculardynamics simulations. Flyer plate simulations were carried out for four boundary types with different energies and excess volumes. These boundaries were chosen as model systems to represent various boundaries observed in “real” materials. Simulations indicate that there is no direct correlation between the void nucleation stress at a boundary and either its energy and excess volume. This result suggests that average properties of grain boundaries alone are not sufficient indicators of the spall strength of a boundary and perhaps local boundary properties need to be taken into account in order to predict its susceptibility to void nucleation for broad ranges of materials. We also present both experimental and simulation results corresponding to the affect of orientation on void nucleation.

  5. COX2 Inhibition Reduces Aortic Valve Calcification In Vivo

    PubMed Central

    Wirrig, Elaine E.; Gomez, M. Victoria; Hinton, Robert B.; Yutzey, Katherine E.

    2016-01-01

    Objective Calcific aortic valve disease (CAVD) is a significant cause of morbidity and mortality, which affects approximately 1% of the US population and is characterized by calcific nodule formation and stenosis of the valve. Klotho-deficient mice were used to study the molecular mechanisms of CAVD as they develop robust aortic valve (AoV) calcification. Through microarray analysis of AoV tissues from klotho-deficient and wild type mice, increased expression of the gene encoding cyclooxygenase 2/COX2 (Ptgs2) was found. COX2 activity contributes to bone differentiation and homeostasis, thus the contribution of COX2 activity to AoV calcification was assessed. Approach and Results In klotho-deficient mice, COX2 expression is increased throughout regions of valve calcification and is induced in the valvular interstitial cells (VICs) prior to calcification formation. Similarly, COX2 expression is increased in human diseased AoVs. Treatment of cultured porcine aortic VICs with osteogenic media induces bone marker gene expression and calcification in vitro, which is blocked by inhibition of COX2 activity. In vivo, genetic loss of function of COX2 cyclooxygenase activity partially rescues AoV calcification in klotho-deficient mice. Moreover, pharmacologic inhibition of COX2 activity in klotho-deficient mice via celecoxib-containing diet reduces AoV calcification and blocks osteogenic gene expression. Conclusions COX2 expression is upregulated in CAVD and its activity contributes to osteogenic gene induction and valve calcification in vitro and in vivo. PMID:25722432

  6. Dystrophic Calcification of the Prostate after Cryotherapy

    PubMed Central

    2014-01-01

    We present a previously undocumented complication of dystrophic calcification of the prostate after cryotherapy. An 87-year-old male presented with recurrent lower urinary tract infections and was found to have an obstructing large calcified mass in the right lobe of the prostate. Subsequently, he underwent transurethral resection of the prostate (TURP) and bladder neck with laser lithotripsy to remove the calculus. We propose that chronic inflammation and necrosis of the prostate from cryotherapy resulted in dystrophic calcification of the prostate. As the use of cryotherapy for the treatment of localized prostate cancer continues to increase, it is important that clinicians be aware of this scenario and the technical challenges it poses. PMID:25548712

  7. A Case of Chronic Calcific Nonalcoholic Pancreatitis

    PubMed Central

    Kangas-Dick, Aaron; Khan, Umair; Awoniyi, Oluwafunbi; Waqar, Shanza; Tun, Nu Nwe; Wong, Cynthia

    2016-01-01

    Tropical Calcific Pancreatitis (TCP) is a type of chronic calcific nonalcoholic pancreatitis. Similar to nonalcoholic chronic pancreatitis, it presents in the second and third decades of life; however this type is reported mostly in the developing tropical and subtropical countries. It is associated with the formation of pancreatic calculi and a high probability of developing insulin-dependent diabetes mellitus. Epidemiologic studies have shown that these patients have an increased risk of developing pancreatic carcinoma. The etiology of TCP remains uncertain, with the current consensus suggesting genetics as well as possible toxicity from consuming large amounts of cassava, a tuber. Definite diagnosis of TCP requires younger age of onset, history of malnutrition, and presence of diabetes mellitus along with extensive pancreatic calcification and ductal calculi. When patients meet most but not all of these conditions the term Idiopathic Chronic Pancreatitis (ICP) is used. This is a case of a 44-year-old man who presented with most features seen in TCP, and however, was diagnosed with ICP. PMID:27957355

  8. Mammographically Detectable Breast Arterial Calcification and Atherosclerosis

    PubMed Central

    Shah, Neeraj; Chainani, Vinod; Delafontaine, Patrice; Abdo, Abir; Lafferty, James; Rafeh, Nidal Abi

    2014-01-01

    Breast arterial calcification (BAC), observed as an incidental finding on screening mammograms, represents degenerative calcific changes occurring in the mammary arteries, with increasing age. The aim of this review is to discuss relevant literature examining relation between BAC and atherosclerosis. After a thorough literature search, in OVID and PubMed, 199 studies were identified, of which 25 were relevant to our review. Data were abstracted from each study and statistical analysis was done, including calculation of odds ratios and construction of forest plots. A total of 35,542 patients were enrolled across 25 studies looking at an association between BAC and coronary artery disease, cardiovascular disease, stroke, cerebral artery disease, carotid and peripheral artery diseases, and coronary artery calcification. A majority of the studies showed a statistically significant relation between BAC and presence of coronary artery disease cardiovascular disease and associated mortality. Sensitivity of BAC in predicting cardiovascular events was low, but specificity was high. BAC was predictive of incident and prevalent stroke but not mortality of stroke. Similarly, BAC was predictive of cerebral, carotid, and peripheral artery diseases. The role of BAC as a surrogate marker of coronary and systemic atherosclerosis is currently uncertain. Its role may be further elucidated by more large-scale prospective studies and clinical experience. PMID:23584424

  9. Calcium intake, vascular calcification, and vascular disease.

    PubMed

    Spence, Lisa A; Weaver, Connie M

    2013-01-01

    Recent research has reported a possible link between calcium supplementation and increased risk of cardiovascular disease and its endpoints in healthy, older adults. To evaluate the current evidence regarding the impact of calcium supplementation on cardiovascular disease risk and to address research gaps, the present review was conducted. Systematic reviews and meta-analyses were included, when available, along with original articles. The articles included in the review were obtained from PubMed using the following search terms: calcium intake, calcium supplementation, cardiovascular disease, myocardial infarction, mortality, and vascular calcification. The majority of the studies reviewed demonstrated no statistically significant adverse or beneficial effect of calcium supplementation on cardiovascular disease or its endpoints. While some studies indicate a possible increased risk, there is a lack of consensus on these findings and a need exists to further elucidate a mechanism. More experimental data are necessary to understand the impact of calcium intake, both levels and sources, on vascular calcification and vascular disease. The use of (41)C kinetic modeling in the Ossabaw swine provides an approach for assessing soft tissue calcification in an atherosclerotic and normal state to address research gaps.

  10. Retropharyngeal calcific tendonitis: report of two cases.

    PubMed

    Razon, Rhea Victoria B; Nasir, Asad; Wu, George S; Soliman, Manal; Trilling, Jeffrey

    2009-01-01

    Retropharyngeal calcific tendonitis is an inflammatory process of the superior oblique tendons of the longus colli muscle, a neck flexor in the upper cervical spine, caused by deposition of calcium hydroxyapatite crystals; the definitive diagnostic test is computed tomography (CT). Presented in this article are two cases seen at our institution. Patients typically present with acute onset of neck pain/spasm, odynophagia, dysphagia, and/or low grade fevers. Leukocytosis and elevated erythrocyte sedimentation rate may be noted. It is important to understand this entity because its signs and symptoms are mimickers of those of the more serious condition of retropharyngeal space abscess. Calcific tendonitis is managed conservatively whereas retropharyngeal abscess requires incision and drainage. Some may argue that this entity is a zebra because its reported incidence in the literature is low. However, most of these studies were done in an era when CT was not yet in vogue. With today's widespread use of CT and its superb ability to visualize the calcification, the true incidence of this condition is probably higher and, thus, it is important for the family practitioner to be aware of this entity. The astute clinician may save the patient from unnecessary diagnostic workup, undue anxiety, and delays in hospital discharge.

  11. Vascular calcification and osteolysis in diabetic neuropathy-is RANK-L the missing link?

    PubMed

    Jeffcoate, W

    2004-09-01

    Diabetic neuropathy is associated with osteopenia and calcification of vascular smooth muscle cells. These changes are most marked in patients with acute neuropathic osteoarthropathy (Charcot foot), in which osteopenia is universal and the prevalence of vascular calcification exceeds 90%. While it has been thought that both osteopenia and vascular calcification may be linked to sympathetic denervation with increased peripheral limb perfusion, the cellular mechanism was not clear. However, the recent recognition that the receptor activator of nuclear factor kappa B ligand (RANK-L)/osteoprotegerin (OPG) signalling pathway is central to the processes regulating bone turnover in a wide variety of medical conditions has raised the possibility that the same cytokines may be involved in the osteolysis which accompanies diabetic neuropathy. This is made more likely by the realisation that the RANK-L/OPG pathway is also thought to mediate the calcification of vascular smooth muscle cells in coronary and peripheral vascular disease. The circumstantial evidence underpinning this hypothesis is reviewed here, and it is suggested that the unregulated activation of RANK-L-mediated effects on bone and arteries may be triggered by the loss of nerve-derived peptides, e.g. calcitonin gene-related peptide, which normally exert a moderating influence on the pathway.

  12. Influence of luminosity bursts on properties of protostellar disks

    NASA Astrophysics Data System (ADS)

    Vorobyov, E. I.; Pavlyuchenkov, Ya. N.; Trinkl, P.

    2014-08-01

    A (2+ 1)-dimensional numerical model for the formation and evolution of young stellar objects with sub-solar masses is presented. The numerical hydrodynamicall code describing the formation and evolution of a protostellar disk in a two-dimensional approximation is supplemented by one-dimensional code for the evolution of the star and an algorithm for establishing the vertical structure of the disk. This code is used to investigate the influence of luminosity bursts with intensities similar to those observed in FU Orionis objects (FUors) on the properties and thermal balance of protostellar disks. A model with gravitational instability and fragmentation of the disk, with subsequent migration of the fragments onto the protostar, is used as a basic model for FUors. Typical FUor bursts ( L ˜ 100 L ⊙) can appreciably influence the thermal balance of their disks and parent envelopes, leading to an increase in the disk temperature by more than a factor of two. On the other hand, massive fragments in the disk are only weakly perturbed by such bursts, partially due to screening by the disk and partially due to their high temperature brought about by adiabatic heating. Apart from massive fragments, the characteristic thermal time scales are appreciably shorter than the dynamical time scales throughout the radial extent of the disk and envelope; this enables the use of a stationary radiative-transfer equation when determining the vertical structure of the disk.

  13. Treatment of hypophosphatemic rickets in generalized arterial calcification of infancy (GACI) without worsening of vascular calcification.

    PubMed

    Ferreira, Carlos R; Ziegler, Shira G; Gupta, Ashutosh; Groden, Catherine; Hsu, Kevin S; Gahl, William A

    2016-05-01

    Patients with generalized arterial calcification of infancy (GACI) develop vascular calcifications early in life. About half of them die within the first 6 months despite optimal medical care. A subset of those who survive eventually develop hypophosphatemic rickets. Since hypophosphatemia and hyperphosphaturia have been previously associated with increased survival in GACI patients, physicians often avoid phosphate repletion as treatment for rickets. As a consequence, GACI patients develop severe rachitic complications such as short stature and skeletal deformities. It appears that the recognition of hypophosphatemia later in life in some GACI patients is a consequence of having survived the first few months of life, and not the cause of their survival per se. Here, we report the long-term follow-up of a GACI patient who was phosphate-repleted for his rickets for more than 7 years without worsening of vascular calcification.

  14. Influence of cell properties on rheological characterization of microalgae suspensions.

    PubMed

    Zhang, Xinru; Jiang, Zeyi; Chen, Liang; Chou, Aihui; Yan, Hai; Zuo, Yi Y; Zhang, Xinxin

    2013-07-01

    The influences of algal cell size and surface charge on rheological properties of microalgae suspensions were investigated. The effective viscosity of two microalgae suspensions, i.e., the freshwater Chlorella sp. and the marine Chlorella sp., was measured as a function of their volume fractions in the range of 0.70-4.31%. The hydrodynamic diameters of the freshwater Chlorella sp. and the marine Chlorella sp. were measured to be 3.13 and 6.00 μm, respectively. The Zeta potentials of these two algal cells were measured to be -23.73 and -81.81 mV, respectively. The intrinsic viscosities of these two microalgae suspensions were further determined to be 24.7 and 16.1, respectively. Combining with theoretical models, these results indicated that the algal cell size has a predominant effect over cell surface charge in affecting rheological properties of microalgae suspensions. Smaller algal cells result in a higher effective viscosity of the microalgae suspension.

  15. Influence of humic acid applications on soil physicochemical properties

    NASA Astrophysics Data System (ADS)

    Gümüş, İ.; Şeker, C.

    2015-09-01

    Soil structure is often said to be the key to soil productivity since a fertile soil, with desirable soil structure and adequate moisture supply, constitutes a productive soil. Soil structure influences soil water movement and retention, erosion, crusting, nutrient recycling, root penetration and crop yield. The objective of this work is to study, humic acid (HA) application on some physical and chemical properties in weak structured soils investigated. The approach involved establishing a plot experiment in the laboratory conditions. Different rates of HA (control, 0.5, 1, 2 and 4 %) were applied to soil at three incubation periods (21, 42 and 62 days). At the end of the each incubation period, the changes in physicochemical properties were measured. Generally, HA addition increased EC values at the all incubation periods. HA applications decreased soil modulus of rupture. Application of HA at the rate of 4 % was significantly increased soil organic carbon contents. HA applications at the rate of 4 % significantly increased both mean soil total nitrogen content and aggregate stability after at three incubation periods (p < 0.05). Therefore, HA was potential to improve structure of soil in short term.

  16. Mild hyperthermia influence on Herceptin® properties

    PubMed Central

    Escoffre, Jean-Michel; Deckers, Roel; Sasaki, Noboru; Bos, Clemens; Moonen, Chrit

    2015-01-01

    Background Mild hyperthermia (mHT) increases the tumor perfusion and vascular permeability, and reduces the interstitial fluid pressure, resulting in better intra-tumoral bioavailability of low molecular weight drugs. This approach is potentially also attractive for delivery of therapeutic macromolecules, such as antibodies. Here, we investigated the effects of mHT on the stability, immunological and pharmacological properties of Herceptin®, a clinically approved antibody, targeting the human epidermal growth factor receptor 2 (HER-2) overexpressed in breast cancer. Results Herceptin® was heated to 37°C (control) and 42°C (mHT) for 1 hour. Formation of Herceptin® aggregates was measured using Nile Red assay. mHT did not result in additional Herceptin® aggregates compared to 37°C, showing the Herceptin® stability is unchanged. Immunological and pharmacological properties of Herceptin® were evaluated following mHT using HER-2 positive breast cancer cells (BT-474). Exposure of Herceptin® to mHT preserved recognition and binding affinity of Herceptin® to HER-2. Western-blot and cell proliferation assays on BT-474 cells showed that mHT left the inhibitory activities of Herceptin® unchanged. Conclusions The stability, and the immunological and pharmacological properties of Herceptin® are not negatively affected by mHT. Further in-vivo studies are required to evaluate the influence of mHT on intra-tumoral bioavailability and therapeutic effectiveness of Herceptin®. PMID:25810700

  17. Calcifications of the palatine tonsillary region: CT demonstration.

    PubMed

    Aspestrand, F; Kolbenstvedt, A

    1987-11-01

    The scans of 100 consecutive patients referred for computed tomographic examinations that included the oropharynx were reviewed with regard to calcifications of the palatine tonsillary region. Calcifications were found in 20% of the female patients and 13% of the male patients. Ten patients had one calculus, and six had two or more. The sizes of the calculi ranged from 1 to 7 mm. Tonsillary calculi must be included among the diagnostic possibilities when survey radiographs of the neck show soft-tissue calcifications.

  18. Dystrophic calcifications after autologous fat injection on face.

    PubMed

    Kim, Dai Hyun; Jang, Hee Won; Kim, Hee Joo; Son, Sang Wook

    2014-06-01

    Autologous fat injection is widely used procedure for various functional and aesthetic purposes. However, it could result in many immediate or delayed complications including dystrophic calcifications. Almost all of the case reports about dystrophic calcification after autologous fat injection were result from the iatrogenic tissue trauma of breast augmentation. This is a report of a 30-year-old patient who developed pathologically proven multiple dystrophic calcifications on the face after autologous fat injection.

  19. Sortilin mediates vascular calcification via its recruitment into extracellular vesicles

    PubMed Central

    Goettsch, Claudia; Hutcheson, Joshua D.; Aikawa, Masanori; Iwata, Hiroshi; Pham, Tan; Nykjaer, Anders; Kjolby, Mads; Rogers, Maximillian; Michel, Thomas; Shibasaki, Manabu; Hagita, Sumihiko; Kramann, Rafael; Singh, Sasha A.

    2016-01-01

    Vascular calcification is a common feature of major cardiovascular diseases. Extracellular vesicles participate in the formation of microcalcifications that are implicated in atherosclerotic plaque rupture; however, the mechanisms that regulate formation of calcifying extracellular vesicles remain obscure. Here, we have demonstrated that sortilin is a key regulator of smooth muscle cell (SMC) calcification via its recruitment to extracellular vesicles. Sortilin localized to calcifying vessels in human and mouse atheromata and participated in formation of microcalcifications in SMC culture. Sortilin regulated the loading of the calcification protein tissue nonspecific alkaline phosphatase (TNAP) into extracellular vesicles, thereby conferring its calcification potential. Furthermore, SMC calcification required Rab11-dependent trafficking and FAM20C/casein kinase 2–dependent C-terminal phosphorylation of sortilin. In a murine model, Sort1-deficiency reduced arterial calcification but did not affect bone mineralization. Additionally, transfer of sortilin-deficient BM cells to irradiated atherosclerotic mice did not affect vascular calcification, indicating a primary role of SMC-derived sortilin. Together, the results of this study identify sortilin phosphorylation as a potential therapeutic target for ectopic calcification/microcalcification and may clarify the mechanism that underlies the genetic association between the SORT1 gene locus and coronary artery calcification. PMID:26950419

  20. Inhibitory role of Notch1 in calcific aortic valve disease.

    PubMed

    Acharya, Asha; Hans, Chetan P; Koenig, Sara N; Nichols, Haley A; Galindo, Cristi L; Garner, Harold R; Merrill, Walter H; Hinton, Robert B; Garg, Vidu

    2011-01-01

    Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD) are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs). We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.

  1. Contrasts in the Sensitivity of Community Calcification to Saturation State Variability Within Temperate and Tropical Marine Environments

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, L.

    2015-12-01

    Ongoing emissions of carbon dioxide (CO2) and invasion of part of this CO2 into the oceans are projected to lower the calcium carbonate saturation state. As a result, the ability of many marine organisms to calcify may be compromised, with significant impacts on ocean ecosystems throughout the Anthropocene. In laboratory manipulations, calcifying organisms have exhibited reduced calcification under elevated pCO2 conditions. However, very few experiments have observed how in situ community calcification, which incorporates complex species interactions, responds to natural variations in carbonate chemistry. Using intensive seawater sampling techniques we assess the community level sensitivity of calcification rates to natural variability in the aragonite saturation state (Ωarag) at both a tropical coral reef and temperate intertidal study site. Both sites experiences large daily variation in Ωarag during low tide due to photosynthesis, respiration, and the time at which the sites are isolated from the open ocean. On hourly timescales, we find that community level rates of calcification have only a weak dependence on variability in Ωarag at the tropical study site. At the temperate study site, although weak Ωarag sensitivity is observed during the day, nighttime community calcification rates are found to be strongly influenced by variability in Ωarag, with greater dissolution rates at lower Ωarag levels. If the short-term sensitivity of community calcification to Ωarag described here is representative of the long-term sensitivity of marine ecosystems to ocean acidification, then one would expect temperate intertidal calcifying communities to be more vulnerable than tropical coral reef calcifying communities. In particular, reductions in net community calcification, in the temperate intertidal zone may be predominately due to the nocturnal impact of ocean acidification.

  2. Calcific Aortic Valve Disease Is Associated with Layer-Specific Alterations in Collagen Architecture

    PubMed Central

    Hutson, Heather N.; Marohl, Taylor; Anderson, Matthew; Eliceiri, Kevin; Campagnola, Paul

    2016-01-01

    Disorganization of the valve extracellular matrix (ECM) is a hallmark of calcific aortic valve disease (CAVD). However, while microarchitectural features of the ECM can strongly influence the biological and mechanical behavior of tissues, little is known about the ECM microarchitecture in CAVD. In this work, we apply advanced imaging techniques to quantify spatially heterogeneous changes in collagen microarchitecture in CAVD. Human aortic valves were obtained from individuals between 50 and 75 years old with no evidence of valvular disease (healthy) and individuals who underwent valve replacement surgery due to severe stenosis (diseased). Second Harmonic Generation microscopy and subsequent image quantification revealed layer-specific changes in fiber characteristics in healthy and diseased valves. Specifically, the majority of collagen fiber changes in CAVD were found to occur in the spongiosa, where collagen fiber number increased by over 2-fold, and fiber width and density also significantly increased. Relatively few fibrillar changes occurred in the fibrosa in CAVD, where fibers became significantly shorter, but did not otherwise change in terms of number, width, density, or alignment. Immunohistochemical staining for lysyl oxidase showed localized increased expression in the diseased fibrosa. These findings reveal a more complex picture of valvular collagen enrichment and arrangement in CAVD than has previously been described using traditional analysis methods. Changes in fiber architecture may play a role in regulating the pathobiological events and mechanical properties of valves during CAVD. Additionally, characterization of the ECM microarchitecture can inform the design of fibrous scaffolds for heart valve tissue engineering. PMID:27685946

  3. Magnesium intake is inversely associated with coronary artery calcification: the Framingham Heart Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    OBJECTIVES: The aim of this study was to examine whether magnesium intake is associated with coronary artery calcification (CAC) and abdominal aortic calcification (AAC). BACKGROUND: Animal and cell studies suggest that magnesium may prevent calcification within atherosclerotic plaques underlying c...

  4. Calcification and photosynthesis of the coral acropora cervicornis under calcium limited conditions

    NASA Technical Reports Server (NTRS)

    Rathfon, Megan; Brewer, Debbie

    1997-01-01

    Differing hypothesis about the function of calcification are based on an interesting dilemma. Is the purpose of calcification mainly a structural and protective one or does calcification serve other functions? Does photosynthesis increase carbonate ion activity and cause calcification or does calcification increase CO2 levels and stimulate photsynthesis? It is proposed that calcification in corals is not dependent upon photosynthesis but upon calcium levels in the water. Under normal ocean conditions, corals convert a certain percentage of energy to photosynthesis and respiration and another percentage to calcification. As corals become nutrient stressed, particularly calcium limited, the ratio of photosynthesis to calcification shifts towards calcification in order to generate protons. The protons generated during calcification may stimulate photosynthesis and aid in the uptake of nutrients and biocarbonates. The results of the calcification experiment show a trend towards increased calcification and decreased photosynthesis when the coral Acropora cervicornis is calcium limited, but the data are inconclusive and further research is needed.

  5. High-Flux Hemodialysis and High-Volume Hemodiafiltration Improve Serum Calcification Propensity

    PubMed Central

    Dekker, Marijke; Pasch, Andreas; van der Sande, Frank; Konings, Constantijn; Bachtler, Matthias; Dionisi, Mauro; Meier, Matthias; Kooman, Jeroen; Canaud, Bernard

    2016-01-01

    Background Calciprotein particles (CPPs) may play an important role in the calcification process. The calcification propensity of serum (T50) is highly predictive of all-cause mortality in chronic kidney disease patients. Whether T50 is therapeutically improvable, by high-flux hemodialysis (HD) or hemodiafiltration (HDF), has not been studied yet. Methods We designed a cross-sectional single center study, and included stable prevalent in-center dialysis patients on HD or HDF. Patients were divided into two groups based on dialysis modality, were on a thrice-weekly schedule, had a dialysis vintage of > 3 months and vascular access providing a blood flow rate > 300 ml/min. Calcification propensity of serum was measured by the time of transformation from primary to secondary CPP (T50 test), by time-resolved nephelometry. Results We included 64 patients, mean convective volume was 21.7L (SD 3.3L). In the pooled analysis, T50 levels increased in both the HD and HDF group with pre- and post-dialysis (mean (SD)) of 244(64) - 301(57) and 253(55) - 304(61) min respectively (P = 0.43(HD vs. HDF)). The mean increase in T50 was 26.29% for HD and 21.97% for HDF patients (P = 0.61 (HD vs. HDF)). The delta values (Δ) of calcium, phosphate and serum albumin were equal in both groups. Baseline T50 was negatively correlated with phosphate, and positively correlated with serum magnesium and fetuin-A. The ΔT50 was mostly influenced by Δ phosphate (r = -0.342; P = 0.002 HD and r = -0.396; P<0.001 HDF) in both groups. Conclusions HD and HDF patients present with same baseline T50 calcification propensity values pre-dialysis. Calcification propensity is significantly improved during both HD and HDF sessions without significant differences between both modalities. PMID:27064679

  6. Environmental control on Emiliania huxleyi coccolithophore calcification in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    D'Amario, Barbara; Grelaud, Michael; Ziveri, Patrizia

    2016-04-01

    The Mediterranean Sea, a "natural laboratory" characterized by strong environmental gradients, is likely to undergo serious alterations due to climate change and ocean acidification. These processes are expected to affect also phytoplankton distribution. Coccolithophores are the only phytoplankton calcifying group and laboratory studies on E. huxleyi, the most abundant and widely distributed species of coccolithophores worldwide, yield strain-specific results. Culture experiments must be integrated with observations in the natural environment to understand existing interactions between drivers, and to verify population structures in different areas. Two transects spanning the south-western and south-eastern basins have been investigated, combining data from April 2011 (Meteor cruise M84/3) and May 2013 (MedSeA cruise). E. huxleyi coccolith morphometry was analyzed to determine average mass and length. These results were then compared with morphological observations performed on the largely dominant E. huxleyi Type A through scanning electron microscope (SEM). We distinguished four main calcification morphologies within E. huxleyi Type A: low-calcified (A1), medium-calcified (A2), high-calcified with closed central area (A3a), and open central area (A3b). E. huxleyi coccolith mass was strongly and positively correlated with the relative abundance of a particular morphology. Moreover, the calcification morphologies were preferentially distributed in the Mediterranean according to specific combinations of environmental variables, which included the carbonate chemistry system. The distribution of E. huxleyi Type A calcification morphologies in the Mediterranean is likely to be influenced by climate changes. Coccolithophore calcification degree is connected to the carbon cycle through photosynthesis / calcification ratio and sedimentation (particulate inorganic and organic carbon reaching the seafloor). This study aims to provide a basis for future investigations on the

  7. Influence of molar ratios on properties of magnesium oxychloride cement

    SciTech Connect

    Li Zongjin . E-mail: zongjin@ust.hk; Chau, C.K.

    2007-06-15

    A parametric study has been conducted to investigate the influences of the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} on the properties of magnesium oxychloride (MOC) cement. By an integrated assessment of the experimental studies of strength development and X-ray diffractograms, together with application of the relevant phase diagram, it is recognized that the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} can significantly affect the properties of MOC cement. For a MOC cement paste possessing a dominance of 5MgO.MgCl{sub 2}.8H{sub 2}O (phase 5) crystals, the molar ratios of MgO/MgCl{sub 2} of 11-17 and H{sub 2}O/MgCl{sub 2} of 12-18 are found to be the most favorite ranges for design purpose. The choose of the molar ratio of H{sub 2}O/MgCl{sub 2} is, however, largely depends on the molar ratio of MgO/MgCl{sub 2} mainly for controlling workability of paste. Therefore, the most critical parameter to be selected in the design process is the molar ratio of MgO/MgCl{sub 2}, although the reactivity of the MgO powder is also important. Besides, the molar ratio can also be affected by the reactivity of the MgO powder to be employed. It is believed that a molar ratio of MgO/MgCl{sub 2} of 13, the most suitable one shown in this study, can be used as a starting point in the normal practice.

  8. Characterising the short-term sensitivity of Californian intertidal community calcification to ocean acidification

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Lester; Caldeira, Ken

    2015-04-01

    Anthropogenic emissions of CO2 and invasion of part of this CO2 into the oceans results in a decrease in seawater pH and a lowering of the calcium carbonate saturation state. The historic and projected decrease of the calcium carbonate saturation state of seawater has the potential to compromise the ability of many marine calcifying organisms to form their calcium carbonate shells or skeletons and is likely to have significant ocean ecosystem impacts over the 21st Century. In laboratory manipulations temperate calcifying organisms have been shown to exhibit reduced calcification as a result of CO2 addition. However, very few experiments have observed how calcification in temperate systems responds to natural variations in seawater carbonate chemistry. We assess the community level sensitivity of Californian tidal pool calcification rates to variability in the calcium carbonate saturation state. Our tidal pool study sites at Bodega Bay in Northern California experience extreme variation in low tide carbonate saturation state due to photosynthetic activity and the time at which the pools are isolated from the open ocean. During our study period, we observed aragonite saturation levels ranging from 0.5 to 9. Photosynthetic activity is largely dependent on temperature and photosynthetic active radiation which vary on a diurnal timescale whereas the time at which pools are isolated from open seawater, and thus the amount by which tide pool carbonate chemistry differs from that of open ocean waters, is largely a consequence of tidal period which varies on a lunar cycle. Because there are substantial uncorrelated components of light, temperature, and seawater carbonate chemistry in our data, one can separate the influence of carbonate saturation state on calcification from the influence of temperature and PAR. This provides an opportunity to characterise the short-timescale sensitivity of tidal pool calcification rates to changes in carbonate saturation state. We show

  9. Secondary calcification and dissolution respond differently to future ocean conditions

    NASA Astrophysics Data System (ADS)

    Silbiger, N. J.; Donahue, M. J.

    2015-01-01

    Climate change threatens both the accretion and erosion processes that sustain coral reefs. Secondary calcification, bioerosion, and reef dissolution are integral to the structural complexity and long-term persistence of coral reefs, yet these processes have received less research attention than reef accretion by corals. In this study, we use climate scenarios from RCP 8.5 to examine the combined effects of rising ocean acidity and sea surface temperature (SST) on both secondary calcification and dissolution rates of a natural coral rubble community using a flow-through aquarium system. We found that secondary reef calcification and dissolution responded differently to the combined effect of pCO2 and temperature. Calcification had a non-linear response to the combined effect of pCO2 and temperature: the highest calcification rate occurred slightly above ambient conditions and the lowest calcification rate was in the highest temperature-pCO2 condition. In contrast, dissolution increased linearly with temperature-pCO2 . The rubble community switched from net calcification to net dissolution at +271 μatm pCO2 and 0.75 °C above ambient conditions, suggesting that rubble reefs may shift from net calcification to net dissolution before the end of the century. Our results indicate that (i) dissolution may be more sensitive to climate change than calcification and (ii) that calcification and dissolution have different functional responses to climate stressors; this highlights the need to study the effects of climate stressors on both calcification and dissolution to predict future changes in coral reefs.

  10. Secondary calcification and dissolution respond differently to future ocean conditions

    NASA Astrophysics Data System (ADS)

    Silbiger, N. J.; Donahue, M. J.

    2014-09-01

    Climate change threatens both the accretion and erosion processes that sustain coral reefs. Secondary calcification, bioerosion, and reef dissolution are integral to the structural complexity and long-term persistence of coral reefs, yet these processes have received less research attention than reef accretion by corals. In this study, we use climate scenarios from RCP8.5 to examine the combined effects of rising ocean acidity and SST on both secondary calcification and dissolution rates of a natural coral rubble community using a flow-through aquarium system. We found that secondary reef calcification and dissolution responded differently to the combined effect of pCO2 and temperature. Calcification had a non-linear response to the combined effect of pCO2-temperature: the highest calcification rate occurred slightly above ambient conditions and the lowest calcification rate was in the highest pCO2-temperature condition. In contrast, dissolution increased linearly with pCO2-temperature. The rubble community switched from net calcification to net dissolution at +272 μatm pCO2 and 0.84 °C above ambient conditions, suggesting that rubble reefs may shift from net calcification to net dissolution before the end of the century. Our results indicate that dissolution may be more sensitive to climate change than calcification, and that calcification and dissolution have different functional responses to climate stressors, highlighting the need to study the effects of climate stressors on both calcification and dissolution to predict future changes in coral reefs.

  11. The time of onset of abnormal calcification in spondylometaepiphyseal dysplasia, short limb-abnormal calcification type.

    PubMed

    Tüysüz, Beyhan; Gazioğlu, Nurperi; Ungür, Savaş; Aji, Dolly Yafet; Türkmen, Seval

    2009-01-01

    A 1-month-old boy with shortness of extremities on prenatal US was referred to our department with a provisional diagnosis of achondroplasia. His height was normal but he had short extremities and platyspondyly, premature carpal epiphyses on both hands, and short tubular bones with irregular metaphyses on radiographs. Re-evaluation of the patient at the age of 1 year revealed very short height and premature calcification of the costal cartilages and epiphyses. Spondylometaepiphyseal dysplasia (SMED), short limb-abnormal calcification type was diagnosed. This condition is a very rare autosomal recessively inherited disorder, and most of the patients die in early childhood due to neurological involvement. At the age of 2 years and 5 months, a CT scan showed narrowing of the cervical spinal canal. One month later he died suddenly because of spinal cord injury. In conclusion early diagnosis is very important because the recurrence risk is high and patients may die due to early neurological complications. The time of onset of abnormal calcifications, a diagnostic finding of the disease, is at the age of around 1 year in most patients. When abnormal calcifications are not yet present, but radiological changes associated with SMED are present, this rare disease must be considered.

  12. Mitral annular calcification and aortic valve calcification may help in predicting significant coronary artery disease.

    PubMed

    Acartürk, Esmeray; Bozkurt, Abdi; Cayli, Murat; Demir, Mesut

    2003-01-01

    Mitral annular calcification (MAC) and aortic valve calcification (AVC) are manifestations of atherosclerosis. To determine whether mitral annular calcification and aortic valve calcification detected by transthoracic echocardiography (TTE) might help in predicting significant coronary artery disease (CAD), 123 patients with significant CAD and 93 patients without CAD detected by coronary angiography were investigated. MAC and AVC identified CAD with a sensitivity and specificity of 60.2%, 55.9% and 74.8%, 52.7%, respectively, and with a negative and a positive predictive values of 51.5%, 64.3% and 61.3% and 67.6%, respectively. The positive predictive value of MAC was greater than gender, hypertension, and hypercholesterolemia. AVC showed a positive predictive value greater than gender, hypertension, family history, and hypercholesterolemia. The negative predictive values of MAC and AVC for CAD were greater than those of all risk factors except diabetes mellitus. In conclusion, presence of MAC and AVC on TTE may help in predicting CAD and should be added to conventional risk factors. Absence of MVC and AVC is a stronger predictor for absence of CAD than all conventional risk factors, except diabetes mellitus. Patients with MAC and AVC should be taken into consideration for the presence of significant CAD and thereby for diagnostic and therapeutic interventions in order to improve the prognosis.

  13. Intracranial Carotid Calcification on Cranial Computed Tomography

    PubMed Central

    Subedi, Deepak; Zishan, Umme Sara; Chappell, Francesca; Gregoriades, Maria-Lena; Sudlow, Cathie; Sellar, Robin

    2015-01-01

    Background and Purpose— Intracranial internal carotid artery calcification is associated with cerebrovascular risk factors and stroke, but few quantification methods are available. We tested the reliability of visual scoring, semiautomated Agatston score, and calcium volume measurement in patients with recent stroke. Methods— We used scans from a prospective hospital stroke registry and included patients with anterior circulation ischemic stroke or transient ischemic stroke whose noncontrast cranial computed tomographic scans were available electronically. Two raters measured semiautomatic quantitative Agatston score, and calcium volume, and performed qualitative visual scoring using the original 4-point Woodcock score and a modified Woodcock score, where each image on which the internal carotid arteries appeared was scored and the slice scores summed. Results— Intra- and interobserver coefficient of variations were 8.8% and 16.5% for Agatston, 8.8% and 15.5% for calcium volume, and 5.7% and 5.4% for the modified Woodcock visual score, respectively. The modified Woodcock visual score correlated strongly with both Agatston and calcium volume quantitative measures (both R2=0.84; P<0.0001); calcium volume increased by 0.47-mm/point increase in modified Woodcock visual score. Intracranial internal carotid artery calcification increased with age by all measures (eg, visual score, Spearman ρ=0.4; P=0.005). Conclusions— Visual scores correlate highly with quantitative intracranial internal carotid artery calcification measures, with excellent observer agreements. Visual intracranial internal carotid artery scores could be a rapid and practical method for epidemiological studies. PMID:26251250

  14. Calcific tendinitis of the rotator cuff

    PubMed Central

    ElShewy, Mohamed Taha

    2016-01-01

    Calcific tendinitis within the rotator cuff tendon is a common shoulder disorder that should be differentiated from dystrophic calcification as the pathogenesis and natural history of both is totally different. Calcific tendinitis usually occurs in the fifth and sixth decades of life among sedentary workers. It is classified into formative and resorptive phases. The chronic formative phase results from transient hypoxia that is commonly associated with repeated microtrauma causing calcium deposition into the matrix vesicles within the chondrocytes forming bone foci that later coalesce. This phase may extend from 1 to 6 years, and is usually asymptomatic. The resorptive phase extends from 3 wk up to 6 mo with vascularization at the periphery of the calcium deposits causing macrophage and mononuclear giant cell infiltration, together with fibroblast formation leading to an aggressive inflammatory reaction with inflammatory cell accumulation, excessive edema and rise of the intra-tendineous pressure. This results in a severely painful shoulder. Radiological investigations confirm the diagnosis and suggest the phase of the condition and are used to follow its progression. Although routine conventional X-ray allows detection of the deposits, magnetic resonance imaging studies allow better evaluation of any coexisting pathology. Various methods of treatment have been suggested. The appropriate method should be individualized for each patient. Conservative treatment includes pain killers and physiotherapy, or “minimally invasive” techniques as needling or puncture and aspiration. It is almost always successful since the natural history of the condition ends with resorption of the deposits and complete relief of pain. Due to the intolerable pain of the acute and severely painful resorptive stage, the patient often demands any sort of operative intervention. In such case arthroscopic removal is the best option as complete removal of the deposits is unnecessary. PMID

  15. Influence of decavanadate clusters on the rheological properties of gelatin.

    PubMed

    Carn, Florent; Djabourov, Madeleine; Coradin, Thibaud; Livage, Jacques; Steunou, Nathalie

    2008-10-09

    The influence of polyoxovanadate clusters ([H(2)V(10)O(28)](4-)) on the thermo-reversible gelation of porcine skin gelatin solution (type A, M w approximately 40 000 g.mol (-1), pH = 3.4 < isoelectric point (IEP) approximately 8) has been investigated as a function of temperature and vanadate concentration by combining rheology and microcalorimetry. This work shows that the rheological properties of the system depend on electrostatic interactions between [H(2)V(10)O(28)](4-) and positively charged gelatin chains. In a first stage, we describe the renaturation of the gelatin triple helices in the presence of decavanadate clusters. We reveal that, when gelatin chains are in coil conformation (30 degrees C < T < 50 degrees C), the inorganic clusters act as physical cross-linkers that govern the visco-elastic properties of the mixture with an exponential dependence of the (G', G'') modulus with the vanadate concentration. Below 30 degrees C, we show that gelatin triple helix nucleation is slightly favored by the presence of vanadate, but above a helix concentration of 0.012 g.cm (-3), G' is fully governed by the helix concentration. During the melting process, we reveal the non-fully reversible behavior of the vanadate/gelatin rheological properties and the stabilization of gelatin triple helices due to vanadate species until 50 degrees C. This non-reversible character has also been observed in the same experimental conditions with collagen/vanadate solutions. This is the first time that such a stabilization of triple helices has been reported in the case of gelatin hydrogels chemically cross-linked or not. We propose to analyze these results by considering that triple helix aggregates should persist because of decavanadate bridging, that the nucleation of an extended triple helix network may induce a strong modification of the vanadate cross-linker distribution in the system, or both, thus promoting the formation of thermally stable vanadate/gelatin micro-gels in the

  16. Ablation of the androgen receptor from vascular smooth muscle cells demonstrates a role for testosterone in vascular calcification

    PubMed Central

    Zhu, Dongxing; Hadoke, Patrick W. F.; Wu, Junxi; Vesey, Alex T.; Lerman, Daniel. A.; Dweck, Marc R.; Newby, David E.; Smith, Lee B.; MacRae, Vicky E.

    2016-01-01

    Vascular calcification powerfully predicts mortality and morbidity from cardiovascular disease. Men have a greater risk of cardiovascular disease, compared to women of a similar age. These gender disparities suggest an influence of sex hormones. Testosterone is the primary and most well-recognised androgen in men. Therefore, we addressed the hypothesis that exogenous androgen treatment induces vascular calcification. Immunohistochemical analysis revealed expression of androgen receptor (AR) in the calcified media of human femoral artery tissue and calcified human valves. Furthermore, in vitro studies revealed increased phosphate (Pi)-induced mouse vascular smooth muscle cell (VSMC) calcification following either testosterone or dihydrotestosterone (DHT) treatment for 9 days. Testosterone and DHT treatment increased tissue non-specific alkaline phosphatase (Alpl) mRNA expression. Testosterone-induced calcification was blunted in VSMC-specific AR-ablated (SM-ARKO) VSMCs compared to WT. Consistent with these data, SM-ARKO VSMCs showed a reduction in Osterix mRNA expression. However, intriguingly, a counter-intuitive increase in Alpl was observed. These novel data demonstrate that androgens play a role in inducing vascular calcification through the AR. Androgen signalling may represent a novel potential therapeutic target for clinical intervention. PMID:27095121

  17. Medial vascular calcification revisited: review and perspectives

    PubMed Central

    Lanzer, Peter; Boehm, Manfred; Sorribas, Victor; Thiriet, Marc; Janzen, Jan; Zeller, Thomas; St Hilaire, Cynthia; Shanahan, Catherine

    2014-01-01

    Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area. PMID:24740885

  18. Cardiovascular calcifications in chronic kidney disease: Potential therapeutic implications.

    PubMed

    Bover, Jordi; Ureña-Torres, Pablo; Górriz, José Luis; Lloret, María Jesús; da Silva, Iara; Ruiz-García, César; Chang, Pamela; Rodríguez, Mariano; Ballarín, José

    Cardiovascular (CV) calcification is a highly prevalent condition at all stages of chronic kidney disease (CKD) and is directly associated with increased CV and global morbidity and mortality. In the first part of this review, we have shown that CV calcifications represent an important part of the CKD-MBD complex and are a superior predictor of clinical outcomes in our patients. However, it is also necessary to demonstrate that CV calcification is a modifiable risk factor including the possibility of decreasing (or at least not aggravating) its progression with iatrogenic manoeuvres. Although, strictly speaking, only circumstantial evidence is available, it is known that certain drugs may modify the progression of CV calcifications, even though a direct causal link with improved survival has not been demonstrated. For example, non-calcium-based phosphate binders demonstrated the ability to attenuate the progression of CV calcification compared with the liberal use of calcium-based phosphate binders in several randomised clinical trials. Moreover, although only in experimental conditions, selective activators of the vitamin D receptor seem to have a wider therapeutic margin against CV calcification. Finally, calcimimetics seem to attenuate the progression of CV calcification in dialysis patients. While new therapeutic strategies are being developed (i.e. vitamin K, SNF472, etc.), we suggest that the evaluation of CV calcifications could be a diagnostic tool used by nephrologists to personalise their therapeutic decisions.

  19. Expression of NPP1 is regulated during atheromatous plaque calcification

    PubMed Central

    Nitschke, Yvonne; Hartmann, Simone; Torsello, Giovanni; Horstmann, Rüdiger; Seifarth, Harald; Weissen-Plenz, Gabriele; Rutsch, Frank

    2011-01-01

    Abstract Mutations of the ENPP1 gene encoding ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) are associated with medial calcification in infancy. While the inhibitory role of matrix proteins such as osteopontin (OPN) with respect to atherosclerotic plaque calcification has been established, the role of NPP1 in plaque calcification is not known. We assessed the degree of plaque calcification (computed tomography), NPP1 and OPN localization (immunohistochemistry) and expression (RT-PCR) in a cohort of 45 patients undergoing carotid endatherectomy for significant stenosis of the internal carotid artery and in normal arteries (N= 50). We correlated NPP1 and OPN expression levels to the degree of plaque calcification, to pro-atherogenic factors and statin therapy. NPP1 was demonstrated in the base and in the shoulder of atherosclerotic plaques. Compared to normal arteries and non-calcified plaques, in calcified plaques NPP1 mRNA was decreased (P < 0.0001). OPN mRNA levels were up-regulated in carotid atheroma. NPP1 and OPN expression levels positively correlated with the degree of plaque calcification (R= 0.54, P= 0.00019 and R= 0.46, P= 0.017, respectively) and with risk factors of atherosclerosis. Expression of the calcification inhibitor NPP1 is down-regulated in calcified atherosclerotic plaques. Our correlation data point to a counter-active mechanism, which in the end turns out to be insufficient to prevent further progression of calcification. PMID:20015201

  20. Left atrial calcification in a hemodialysis patient with cor triatriatum.

    PubMed

    Peces, R; Pobes, A; Rodriguez, M; Simarro, C; Iglesias, G; Simarro, E

    2000-05-01

    Myocardial calcification is a rare manifestation of abnormal calcium metabolism seen in some patients with chronic renal failure. This report describes the transesophageal echocardiographic and spiral computed tomography (CT) findings in a young hemodialysis female with severe secondary hyperparathyroidism. These findings included calcification of the multiperforated membrane of a cor triatriatum and the wall of the left atrium.

  1. [Endomyocardial fibrosis with massive calcification of the left ventricle].

    PubMed

    Trigo, Joana; Camacho, Ana; Gago, Paula; Candeias, Rui; Santos, Walter; Marques, Nuno; Matos, Pedro; Brandão, Victor; Gomes, Veloso

    2010-03-01

    Endomyocardial fibrosis is a rare disease, endemic in tropical countries. It is characterized by fibrosis of the endocardium that can extend to myocardium. Important calcification of the endocardium is rare with only a few cases reported in the literature. We report a case of endomyocardial fibrosis in a european caucasian patient, associated with massive calcification of left ventricle.

  2. Matrix Gla Protein polymorphisms are associated with coronary artery calcification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Matrix Gla Protein (MGP) is a key regulator of vascular calcification. Genetic variation at the MGP locus could modulate the development of coronary artery calcification (CAC). We examined the cross-sectional association between MGP SNPs [rs1800802 (T-138C), rs1800801 (G-7A),and rs4236 (Ala102Thr)...

  3. Susceptibility weighted imaging: differentiating between calcification and hemosiderin*

    PubMed Central

    Barbosa, Jeam Haroldo Oliveira; Santos, Antonio Carlos; Salmon, Carlos Ernesto Garrido

    2015-01-01

    Objective To present a detailed explanation on the processing of magnetic susceptibility weighted imaging (SWI), demonstrating the effects of echo time and sensitive mask on the differentiation between calcification and hemosiderin. Materials and Methods Computed tomography and magnetic resonance (magnitude and phase) images of six patients (age range 41– 54 years; four men) were retrospectively selected. The SWI images processing was performed using the Matlab’s own routine. Results Four out of the six patients showed calcifications at computed tomography images and their SWI images demonstrated hyperintense signal at the calcification regions. The other patients did not show any calcifications at computed tomography, and SWI revealed the presence of hemosiderin deposits with hypointense signal. Conclusion The selection of echo time and of the mask may change all the information on SWI images, and compromise the diagnostic reliability. Amongst the possible masks, the authors highlight that the sigmoid mask allows for contrasting calcifications and hemosiderin on a single SWI image. PMID:25987750

  4. Mechanisms of ectopic calcification: implications for diabetic vasculopathy

    PubMed Central

    Fadini, Gian Paolo

    2015-01-01

    Vascular calcification (VC) is the deposition of calcium/phosphate in the vasculature, which portends a worse clinical outcome and predicts major adverse cardiovascular events. VC is an active process initiated and regulated via a variety of molecular signalling pathways. There are mainly two types of calcifications: the media VC and the intima VC. All major risk factors for cardiovascular disease (CVD) have been linked to the presence/development of VC. Besides the risk factors, a genetic component is also operative to determine arterial calcification. Several events take place before VC is established, including inflammation, trans-differentiation of vascular cells and homing of circulating pro-calcific cells. Diabetes is an important predisposing factor for VC. Compared with non-diabetic subjects, patients with diabetes show increased VC and higher expression of bone-related proteins in the medial layer of the vessels. In this review we will highlight the mechanisms underlying vascular calcification in diabetic patients. PMID:26543821

  5. Calcific Uremic Arteriolopathy: An Underrecognized Entity

    PubMed Central

    Kumar, Victoria Ann

    2011-01-01

    Calcific uremic arteriolopathy (CUA), or calciphylaxis, is an uncommon and underrecognized disease that often occurs in the setting of chronic kidney disease or end-stage renal disease. It is characterized by small-vessel calcification, although many times it is associated with normal serum levels of calcium, phosphorus, and parathyroid hormone. The lesions appear as necrotic eschars, ulcerations, indurated nodules, and dry gangrene and are usually very painful. Diagnosis is based on clinical judgment and recognition of characteristic skin lesions. Biopsy can be performed but may be complicated by poor wound healing. Treatment of CUA involves rigorous wound care, strict control of mineral metabolism with avoidance of calcium and vitamin D analogs, and pain control. Other treatment options include sodium thiosulfate, hyperbaric oxygen therapy, daily hemodialysis using low-calcium dialysate, and bisphosphonates. Even with treatment, CUA is associated with significant morbidity and mortality. The patient in the case reported here had characteristic skin lesions and several risk factors for CUA, but diagnosis was delayed. PMID:21841931

  6. Vascular calcifications, vertebral fractures and mortality in haemodialysis patients

    PubMed Central

    Rodríguez-García, Minerva; Gómez-Alonso, Carlos; Naves-Díaz, Manuel; Diaz-Lopez, Jose Bernardino; Diaz-Corte, Carmen; Cannata-Andía, Jorge B.

    2009-01-01

    Background. Vascular calcifications and the bone fractures caused by abnormal bone fragility, also called osteoporotic fractures, are frequent complications associated with chronic kidney diseases (CKD). The aim of this study was to investigate the association between vascular calcifications, osteoporotic bone fractures and survival in haemodialysis (HD) patients. Methods. A total of 193 HD patients were followed up to 2 years. Vascular calcifications and osteoporotic vertebral fractures (quoted just as vertebral fractures in the text) were assessed by thoracic, lumbar spine, pelvic and hand X-rays and graded according to their severity. Clinical, biochemical and therapeutic data gathered during the total time spent on HD were collected. Results. The prevalence of aortic calcifications was higher in HD patients than in a random-based general population (79% versus 37.5%, P < 0.001). Total time on any renal replacement therapy (RRT) and diabetes were positively associated with a higher prevalence of vascular calcifications. In addition to these factors, time on HD was also positively associated with the severity of vascular calcifications, and higher haemoglobin levels were associated with a lower prevalence of severe vascular calcifications in large and medium calibre arteries. The prevalence of vertebral fractures in HD patients was similar to that of the general population (26.5% versus 24.1%). Age and time on HD showed a positive and statistically significant association with the prevalence of vertebral fractures. Vascular calcifications in the medium calibre arteries were associated with a higher rate of prevalent vertebral fractures. In women, severe vascular calcifications and vertebral fractures were positively associated with mortality [RR = 3.2 (1.0–10.0) and RR = 4.8 (1.7–13.4), respectively]. Conclusions. Positive associations between vascular calcifications, vertebral fractures and mortality have been found in patients on HD. PMID:18725376

  7. Targeting vascular calcification: softening-up a hard target.

    PubMed

    Kapustin, Alexander; Shanahan, Catherine M

    2009-04-01

    Widespread vascular calcification is a ubiquitous feature of aging and is prevalent in association with a number of common pathologies including atherosclerosis, renal failure, and diabetes. Once thought of as innocuous, emerging evidence suggests that calcification is causal in precipitating vascular events and mediating chronic cardiovascular damage, independent of disease context. Importantly, a large body of data has shed light on the factors that favor the formation of calcification in vivo, as well as on the complex mechanisms that initiate and promote it. This has identified some novel targets and allowed for the possibility that calcification can potentially be blocked and ultimately regressed. Targets include local and circulating inhibitors of calcification as well as factors that may ameliorate vascular smooth muscle cell (VSMC) apoptosis. Despite this, the vasculature remains a difficult tissue to target and currently there are no effective treatments in general use. More crucially, any potential treatments will need to be carefully evaluated as they may impinge on bone metabolism. Our best hope for the near future is to normalize factors associated with accelerated calcification in pathologies such as renal failure where, aberrant mineral metabolism, as well as treatment regimes, may contribute to the initiation and progression of calcification.

  8. Observer study to evaluate the simulation of mammographic calcification clusters

    NASA Astrophysics Data System (ADS)

    Sousa, Maria A. Z.; Marcomini, Karem D.; Bakic, Predrag R.; Maidment, Andrew D. A.; Schiabel, Homero

    2016-03-01

    Numerous breast phantoms have been developed to be as realistic as possible to ensure the accuracy of image quality analysis, covering a greater range of applications. In this study, we simulated three different densities of the breast parenchyma using paraffin gel, acrylic plates and PVC films. Hydroxyapatite was used to simulate calcification clusters. From the images acquired with a GE Senographe DR 2000D mammography system, we selected 68 regions of interest (ROIs) with and 68 without a simulated calcification cluster. To validate the phantom simulation, we selected 136 ROIs from the University of South Florida's Digital Database for Screening Mammography (DDSM). Seven trained observers performed two observer experiments by using a high-resolution monitor Barco mod. E-3620. In the first experiment, the observers had to distinguish between real or phantom ROIs (with and without calcification). In the second one, the observers had to indicate the ROI with calcifications between a pair of ROIs. Results from our study show that the hydroxyapatite calcifications had poor contrast in the simulated breast parenchyma, thus observers had more difficulty in identifying the presence of calcification clusters in phantom images. Preliminary analysis of the power spectrum was conducted to investigate the radiographic density and the contrast thresholds for calcification detection. The values obtained for the power spectrum exponent (β) were comparable with those found in the literature.

  9. Intracranial physiological calcifications evaluated with cone beam CT

    PubMed Central

    Sedghizadeh, P P; Nguyen, M; Enciso, R

    2012-01-01

    Objectives The purpose of this study was to evaluate cone beam CT (CBCT) scans for the presence of physiological and pathological intracranial calcifications. Methods CBCT scans from male and female patients that met our ascertainment criteria were evaluated retrospectively (n = 500) for the presence of either physiological or pathological intracranial calcifications. Results Out of the 500 patients evaluated, 176 had evidence of intracranial physiological calcification (35.2% prevalence), and none had evidence of pathological calcification. There was a 3:2 male-to-female ratio and no ethnic predilection; the ages of affected patients ranged from 13 years to 82 years with a mean age of 52 years. The majority of calcifications appeared in the pineal/habenular region (80%), with some also appearing in the choroid plexus region bilaterally (12%), and a smaller subset appearing in the petroclinoid ligament region bilaterally (8%). Conclusions Intracranial physiological calcifications can be a common finding on CBCT scans, whereas pathological intracranial calcifications are rare. PMID:22842632

  10. Role of Vitamin D in Uremic Vascular Calcification

    PubMed Central

    Zheng, Jing-Quan

    2017-01-01

    The risk of cardiovascular death is 10 times higher in patients with CKD (chronic kidney disease) than in those without CKD. Vascular calcification, common in patients with CKD, is a predictor of cardiovascular mortality. Vitamin D deficiency, another complication of CKD, is associated with vascular calcification in patients with CKD. GFR decline, proteinuria, tubulointerstitial injury, and the therapeutic dose of active form vitamin D aggravate vitamin D deficiency and reduce its pleiotropic effect on the cardiovascular system. Vitamin D supplement for CKD patients provides a protective role in vascular calcification on the endothelium by (1) renin-angiotensin-aldosterone system inactivation, (2) alleviating insulin resistance, (3) reduction of cholesterol and inhibition of foam cell and cholesterol efflux in macrophages, and (4) modulating vascular regeneration. For the arterial calcification, vitamin D supplement provides adjunctive role in regressing proteinuria, reverse renal osteodystrophy, and restoring calcification inhibitors. Recently, adventitial progenitor cell has been linked to be involved in the vascular calcification. Vitamin D may provide a role in modulating adventitial progenitor cells. In summary, vitamin D supplement may provide an ancillary role for ameliorating uremic vascular calcification. PMID:28286758

  11. Serum Fetuin-A Levels Are Associated with Vascular Calcifications and Predict Cardiovascular Events in Renal Transplant Recipients

    PubMed Central

    Maréchal, Céline; Schlieper, Georg; Nguyen, Pauline; Krüger, Thilo; Coche, Emmanuel; Robert, Annie; Floege, Jorgen; Goffin, Eric; Jadoul, Michel

    2011-01-01

    Summary Background and objectives Vascular calcifications predict cardiovascular disease, the major cause of death in renal transplant recipients (RTRs). We studied the determinants of fetuin-A, a potent circulating calcification inhibitor encoded by the AHSG gene, and tested its association with vascular calcifications and long-term survival and cardiovascular events (CVEs) in RTRs. Design, setting, participants, & measurements Two hundred seventy-seven prevalent RTRs from a single center were included. CVEs and deaths were prospectively recorded during a 5-year follow-up. Results Independent determinants of lower serum fetuin-A levels were lower plasma cholesterol, the AHSG rs4918 G allele, and history of smoking. Low serum fetuin-A level was a determinant of aortic calcifications (assessed using spiral CT). Low fetuin-A levels (≤0.47 g/L, first quintile) were independently associated with CVEs and deaths (hazard ratio = 1.83; 95% confidence interval, 1.07 to 3.04). The association was confirmed for all-cause mortality, and the major adverse cardiovascular endpoints were analyzed separately. Patients with low fetuin-A and high high-sensitivity C-reactive protein (>4.36 mg/L, fourth quintile) levels had a 3.5-fold increased risk of all-cause mortality and CVEs. In the presence of inflammation, CVE-free survival was influenced by common variants in the AHSG gene. Conclusions These data show that low fetuin-A levels are independently associated with aortic calcifications and a higher risk of CVEs and mortality. They support fetuin-A as a circulating biomarker able to identify RTRs at risk for vascular calcifications and CVEs. PMID:21527649

  12. [Vascular Calcification - Pathological Mechanism and Clinical Application - . Role of vascular smooth muscle cells in vascular calcification].

    PubMed

    Kurabayashi, Masahiko

    2015-05-01

    Vascular calcification is commonly seen with aging, chronic kidney disese (CKD), diabetes, and atherosclerosis, and is closely associated with cardiovascular morbidity and mortality. Vascular calcification has long been regarded as the final stage of degeneration and necrosis of arterial wall and a passive, unregulated process. However, it is now known to be an active and tightly regulated process involved with phenotypic transition of vascular smooth muscle cells (VSMC) that resembles bone mineralization. Briefly, calcium deposits of atherosclerotic plaque consist of hydroxyapatite and may appear identical to fully formed lamellar bone. By using a genetic fate mapping strategy, VSMC of the vascular media give rise to the majority of the osteochondrogenic precursor- and chondrocyte-like cells observed in the calcified arterial media of MGP (- / -) mice. Osteogenic differentiation of VSMC is characterized by the expression of bone-related molecules including bone morphogenetic protein (BMP) -2, Msx2 and osteopontin, which are produced by osteoblasts and chondrocytes. Our recent findings are that (i) Runx2 and Notch1 induce osteogenic differentiation, and (ii) advanced glycation end-product (AGE) /receptor for AGE (RAGE) and palmitic acid promote osteogenic differentiation of VSMC. To understand of the molecular mechanisms of vascular calcification is now under intensive research area.

  13. Pathological calcifications studied with micro-CT

    NASA Astrophysics Data System (ADS)

    Stock, Stuart R.; Rajamannan, Nalini M.; Brooks, Ellen R.; Langman, Craig B.; Pachman, Lauren M.

    2004-10-01

    The microstructure of pathological biomineral deposits has received relatively little attention, perhaps, in part because of the difficulty preparing samples for microscopy. MicroCT avoids these difficulties, and laboratory microCT results are reviewed for aortic valve calcification (human as well as a rabbit model), for human renal calculi (stones) and for calcinoses formed in juvenile dermatomyositis (JDM). In calcified aortic valves of rabbits, numerical analysis of the data shows statistically significant correlation with diet. In a large kidney stone the pattern of mineralization is clearly revealed and may provide a temporal blueprint for stone growth. In JDM calcified deposits, very different microstructures are observed and may be related to processes unique to this disease.

  14. Basic mechanisms of calcific aortic valve disease.

    PubMed

    Mathieu, Patrick; Boulanger, Marie-Chloé

    2014-09-01

    Calcific aortic valve disease (CAVD) is the most common heart valve disorder. There is no medical treatment to prevent and/or promote the regression of CAVD. Hence, it is of foremost importance to delineate and understand the key basic underlying mechanisms involved in CAVD. In the past decade our comprehension of the underpinning processes leading to CAVD has expanded at a fast pace. Hence, our understanding of the basic pathobiological processes implicated in CAVD might lead eventually to the development of novel pharmaceutical therapies for CAVD. In this review, we discuss molecular processes that are implicated in fibrosis and mineralization of the aortic valve. Specifically, we address the role of lipid retention, inflammation, phosphate signalling and osteogenic transition in the development of CAVD. Interplays between these different processes and the key regulation pathways are discussed along with their clinical relevance.

  15. Calcification of in vitro developed hypertrophic cartilage

    SciTech Connect

    Tacchetti, C.; Quarto, R.; Campanile, G.; Cancedda, R.

    1989-04-01

    We have recently reported that dedifferentiated cells derived from stage 28-30 chick embryo tibiae, when transferred in suspension culture in the presence of ascorbic acid, develop in a tissue closely resembling hypertrophic cartilage. Ultrastructural examination of this in vitro formed cartilage showed numerous matrix vesicles associated with the extracellular matrix. In the present article we report that the in vitro developed hypertrophic cartilage undergoes calcification. We indicate a correlation between the levels of alkaline phosphatase activity and calcium deposition at different times of development. Following the transfer of cells into suspension culture and an initial lag phase, the level of alkaline phosphatase activity rapidly increased. In most experiments the maximum of activity was reached after 5 days of culture. When alkaline phosphatase activity and /sup 45/Ca deposition were measured in the same experiment, we observed that the increase in alkaline phosphatase preceded the deposition of nonwashable calcium deposits in the cartilage.

  16. Orbital melanoma with calcification: A diagnostic dilemma

    PubMed Central

    Bains, Sukhdeep; Kim, Usha; Shanti, R

    2016-01-01

    Primary orbital melanoma is rare and has varied initial presentation. A 28-year-old female presented with proptosis and decreased vision in the left eye. Computed tomography scan showed an orbital mass with contrast enhancement and calcification around the optic nerve leading to a diagnosis of meningioma. The patient chose to be on observation. Loss of vision with an increase in proptosis was seen at 6 months follow-up. On surgical exploration, a well-defined pigmented mass was seen encasing the optic nerve. Histopathological analysis revealed a malignant melanoma. Metastatic workup was negative. Left eye lid sparing exenteration was done. A high index of suspicion is necessary in a rapidly growing suspected optic nerve sheath meningioma and a differential diagnosis including orbital melanoma be considered. PMID:28112137

  17. Cerebroretinal microangiopathy with calcifications and cysts

    PubMed Central

    Xu, Wenrui; Zhao, Jiuliang; Zhu, Yicheng; Zhang, Weihong

    2017-01-01

    Abstract Rational: Cerebroretinal microangiopathy with calcifications and cysts (CRMCC) is believed to be an autosomal recessive genetic disease, with disorders in multisystem organs. Its characteristic neurological disorders manifested on neuroimaging are a triad of leukoencephalopathy, intracranial calcifications, and parenchymal cysts. In this paper, we report a CRMCC patient with multisystem involvement, focusing on the neuroimaging features, to get a better understanding of the rare disease and improve our diagnostic ability. Patient Concerns: The 23-year-old female patient firstly presented with an adolescence onset of ophthalmological manifestations. Four years later, hematological and neurological disorders occurred, the latter of which demonstrated a relatively slow progression in the following 7 years preceding her presentation to our hospital. Interventions: During hospitalization, disorders involving digestive, cardiovascular and respiratory systems were also detected. In addition, a more comprehensive depiction of neurological disorders on neuroimaging was also obtained. Diagnoses: On the basis of multiple system disorders and the detection of mutations in conserved telomere maintenance component 1(CTC1) gene, a diagnosis of CRMCC was made. Outcomes: After supportive therapy during her 4-week hospitalization, the patient's general condition improved and was released from the hospital. Lessons: CRMCC could be primarily diagnosed with the aid of its multiple system disorders and remarkable neuroimaging features. Cerebral micro hemorrhages determined by the combination of CT and T2∗-weighted magnetic resonance images in our case could provide some additional information for diagnosis. Furthermore, several other associated disorders were depicted for the first time in our case, expanding the clinical spectrum of CRMCC. PMID:28072696

  18. Soft-tissue calcification after subcutaneus emphysema in a neonate

    SciTech Connect

    Naidech, H.J.; Chawla, H.S.

    1982-08-01

    Bilateral, almost symmetric, calcifications of the soft tissues after subcutaneous emphysema have not, to our knowledge, been described. Because of the close clinical and radiographic evaluation in our case, the finding of calcinosis was not a diagnostic problem. Several 1.5 mm computed tomographic (CT) sections of the thorax were scanned and they were confirmatory in showing the distribution of the calcifications. Since subcutaneous emphysema is commonplace, and calcification after it is apparently unknown, the literature was reviewed and an additional cause of soft-tissue calcinosis is presented.

  19. An unusual case of extensive peritoneal calcification: A case report

    PubMed Central

    Roriz, Diogo; Abreu, Inês; Costa, João F.; Soares, Pedro Belo; Caseiro-Alves, Filipe

    2014-01-01

    The peritoneum is the largest serous membrane of the body and can be exposed to several injuries that may cause abnormal findings on imaging exams. Linear peritoneal calcification is remarkably rare, usually secondary to long duration peritoneal dialysis. We report an uncommon case of extensive peritoneal calcification in a 39-year-old female without long exposure to peritoneal dialysis solutions, in which peritoneal calcification could be linked to Alport syndrome and previous adverse reaction to intraperitoneal iodinated contrast. Radiologist should be aware of this and related imaging findings, know when to search for them as well as understand their clinical value. PMID:26937431

  20. Calcification response of a key phytoplankton family to millennial-scale environmental change

    PubMed Central

    McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Ferretti, P.; Greaves, M.; Rickaby, R. E. M.

    2016-01-01

    Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments. PMID:27677230

  1. Calcification response of a key phytoplankton family to millennial-scale environmental change.

    PubMed

    McClelland, H L O; Barbarin, N; Beaufort, L; Hermoso, M; Ferretti, P; Greaves, M; Rickaby, R E M

    2016-09-28

    Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth's climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments.

  2. Calcification response of a key phytoplankton family to millennial-scale environmental change

    NASA Astrophysics Data System (ADS)

    McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Ferretti, P.; Greaves, M.; Rickaby, R. E. M.

    2016-09-01

    Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments.

  3. Magnesium prevents β-glycerophosphate-induced calcification in rat aortic vascular smooth muscle cells.

    PubMed

    Bai, Yaling; Zhang, Junxia; Xu, Jinsheng; Cui, Liwen; Zhang, Huiran; Zhang, Shenglei; Feng, Xunwei

    2015-07-01

    Vascular calcification (VC), in which high serum phosphate plays a critical role, is one major problem in patients with chronic kidney disease. Clinical studies report that magnesium has a protective effect on VC. However, the studies regarding the impact of high serum magnesium on VC at a cellular level are few and require further investigation. Therefore, the present study explored the effect of magnesium on calcification induced by β-glycerophosphate (BGP) in rat aortic vascular smooth muscle cells (RAVSMCs). In the present study, the addition of magnesium decreased calcium deposition, which was increased by BGP. Higher magnesium levels inhibited BGP-induced alkaline phosphatase (ALP) activity and decreased the expression of core-binding factor α-1 (Cbfα1). In conclusion, higher magnesium levels prevented BGP-induced calcification in RAVSMCs and inhibited the expression of Cbfα1 and ALP. Thus, magnesium is influencing the expression of Cbfα1 and ALP associated with VC and may have the potential to serve as a role for VC in clinical situations.

  4. In vitro evaluation of anti-calcification and anti-coagulation on sulfonated chitosan and carrageenan surfaces.

    PubMed

    Campelo, Clayton Souza; Lima, Luana Dias; Rebêlo, Luciana Magalhães; Mantovani, Diego; Beppu, Marisa Masumi; Vieira, Rodrigo Silveira

    2016-02-01

    In recent years, great effort has been devoted to the development of biomaterials that come into contact with blood. The surfaces of these materials need to be of suitable mechanical strength, and present anti-thrombogenic and anti-calcification properties. Chitosan is a natural polymer that has attracted attention due to its potential to act as a biomaterial. However, chitosan contains amino groups in its structure that may promote thrombogenesis and calcification. A strategy to reduce these properties constitutes the introduction of sulfonate groups (R-SO3-) in the chitosan chain. Another interesting biopolymer with similar characteristics to those of heparin is carrageenan, which has sulfate groups in its structure. As such, we evaluated “in vitro” calcification and thrombogenic processes on surfaces of pristine and sulfonated chitosan and on polyelectrolyte complexes (PEC) of chitosan and carrageenan. Results indicate that PEC demonstrate significant reductions in calcification and thrombogenic potential, probably due to the presence of sulfonate groups in both the carrageenan and treated chitosan.

  5. Influence of imperfections on effective properties of cellular solids

    SciTech Connect

    Grenestedt, J.L.

    1998-12-31

    The mechanical properties of cellular solids, or solid foams, is affected by imperfections such as wavy distortions of cell walls, variations in cell wall thickness, non-uniform cell shape, etc. The present paper is focused mainly on elastic stiffnesses of closed cell cellular solids. A perfect model is first discussed and shown to predict the behavior of PVC foams well. However, this model over-estimates the stiffnesses of aluminum foams. The relatively poor properties of the aluminum foam are believed to be caused by imperfections in the cells. The main body of the paper focuses on modeling different kinds of imperfections, and analyzing their impact on foam properties.

  6. [Study on influence between activated carbon property and immobilized biological activated carbon purification effect].

    PubMed

    Wang, Guang-zhi; Li, Wei-guang; He, Wen-jie; Han, Hong-da; Ding, Chi; Ma, Xiao-na; Qu, Yan-ming

    2006-10-01

    By means of immobilizing five kinds of activated carbon, we studied the influence between the chief activated carbon property items and immobilized bioactivated carbon (IBAC) purification effect with the correlation analysis. The result shows that the activated carbon property items which the correlation coefficient is up 0.7 include molasses, abrasion number, hardness, tannin, uniform coefficient, mean particle diameter and effective particle diameter; the activated carbon property items which the correlation coefficient is up 0.5 include pH, iodine, butane and tetrachloride. In succession, the partial correlation analysis shows that activated carbon property items mostly influencing on IBAC purification effect include molasses, hardness, abrasion number, uniform coefficient, mean particle diameter and effective particle diameter. The causation of these property items bringing influence on IBAC purification is that the activated carbon holes distribution (representative activated carbon property item is molasses) provides inhabitable location and adjust food for the dominance bacteria; the mechanical resist-crash property of activated carbon (representative activated carbon property items: abrasion number and hardness) have influence on the stability of biofilm; and the particle diameter size and distribution of activated carbon (representative activated carbon property items: uniform coefficient, mean particle diameter and effective particle diameter) can directly affect the force of water in IBAC filter bed, which brings influence on the dominance bacteria immobilizing on activated carbon.

  7. Dissolution Dominating Calcification Process in Polar Pteropods Close to the Point of Aragonite Undersaturation

    PubMed Central

    Bednaršek, Nina; Tarling, Geraint A.; Bakker, Dorothee C. E.; Fielding, Sophie; Feely, Richard A.

    2014-01-01

    Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Ωar). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Ωar∼0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Ωar levels slightly above 1 and lower at Ωar levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Ωar derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Ωar levels close to 1, with net shell growth ceasing at an Ωar of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean. PMID:25285916

  8. Dissolution dominating calcification process in polar pteropods close to the point of aragonite undersaturation.

    PubMed

    Bednaršek, Nina; Tarling, Geraint A; Bakker, Dorothee C E; Fielding, Sophie; Feely, Richard A

    2014-01-01

    Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Ω(ar)). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Ω(ar) ∼ 0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Ω(ar) levels slightly above 1 and lower at Ω(ar) levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Ω(ar) derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Ω(ar) levels close to 1, with net shell growth ceasing at an Ω(ar) of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean.

  9. Calcein labelling and electrophysiology: insights on coral tissue permeability and calcification

    PubMed Central

    Tambutté, Eric; Tambutté, Sylvie; Segonds, Natacha; Zoccola, Didier; Venn, Alexander; Erez, Jonathan; Allemand, Denis

    2012-01-01

    The mechanisms behind the transfer of molecules from the surrounding sea water to the site of coral calcification are not well understood, but are critical for understanding how coral reefs are formed. We conducted experiments with the fluorescent dye calcein, which binds to calcium and is incorporated into growing calcium carbonate crystals, to determine the permeability properties of coral cells and tissues to this molecule, and to determine how it is incorporated into the coral skeleton. We also compared rates of calcein incorporation with rates of calcification measured by the alkalinity anomaly technique. Finally, by an electrophysiological approach, we investigated the electrical resistance of coral tissues in order to better understand the role of tissues in ionic permeability. Our results show that (i) calcein passes through coral tissues by a paracellular pathway, (ii) intercellular junctions control and restrict the diffusion of molecules, (iii) intercellular junctions should have pores of a size higher than 13 Å and lower than 20 nm, and (iv) the resistance of the tissues owing to paracellular junctions has a value of 477 ± 21 Ohm cm2. We discuss the implication of our results for the transport of calcium involved in the calcification process. PMID:21613296

  10. Influence of initial flaws on the mechanical properties of nacre.

    PubMed

    Anup, S

    2015-06-01

    Nacre is a bio-composite made up of hard mineral and soft protein, and has excellent mechanical properties. This paper examines the effect of naturally occurring defects (initial flaws) in nacre on its mechanical properties such as toughness and strength. A random fuse model is developed incorporating initial flaws. Numerical simulations show that initial flaws affect different mechanical properties at different rates. The variation in the experimentally obtained mechanical properties of nacre reported in the literature is shown to be due to initial flaws. The stress in the mineral and protein increases due to initial flaws, but by different amounts. The results obtained in this study are useful for gaining insight into the failure of nacre and development of nacre-inspired composites.

  11. Genetics Home Reference: familial idiopathic basal ganglia calcification

    MedlinePlus

    ... in regulating phosphate levels within the body (phosphate homeostasis) by transporting phosphate across cell membranes. The SLC20A2 ... link familial idiopathic basal ganglia calcification with phosphate homeostasis. Nat Genet. 2012 Feb 12;44(3):254- ...

  12. [The hemodynamic characterization of the diabetic patient with arterial calcifications].

    PubMed

    Vega Gómez, M E; Ley Pozo, J; Aldama Figueroa, A; Lima Santana, B; Montalvo Diago, J; Bustillo, C; Fernández Boloña, A; Gutiérrez Jiménez, O; Ramirez Muñoz, O; Martínez Hernández, R

    1993-01-01

    This study was designed to describe the presence of calcifications according to the clinical features of the diabetic patient and the hemodynamics of the calcified arteries. With this purpose, 197 lower limbs from diabetic patients (type I and II) and carbon-hydrate intolerant patients, were studied. In all of the patients, the pressure ratio leg/arm was measured. On the same way, the arterial flow velocity was recorded using the Doppler ultrasonography on the pedia and postero-tibial arteries. The arterial calcifications, evident on the radiography of the foot, were more frequent between the type I patients and the neuro-infections diabetic foot. According to the hemodynamics point of view, we found a trend of association of more pathologic arterial flow velocity curves with the presence of calcifications (specially on the intima layer). It was also remarkable that an arterial incomprensibility was always associated with arterial calcifications.

  13. Acute Calcific Tendinitis of the Rectus Femoris: A Case Series

    PubMed Central

    Kobayashi, Hideo; Kaneko, Haruka; Homma, Yasuhiro; Baba, Tomonori; Kaneko, Kazuo

    2015-01-01

    Introduction: Periarticular calcific tendinitis is a common cause of Orthopedic outpatient referral. Calcific tendinitis of the rectus femoris, however, is very rare and not well known. Due to its rarity, correct diagnosis and prompt treatment are not fully understood. Case Report: Two females (38 and 40 years old) of acute calcific tendinitis of the rectus femoris with the good clinical course without any operative treatment were presented. The pain was managed with oral non-steroidal antiinflammatory drugs and/or local steroid injection. Interval radiographic assessment showed complete resorption of the calcification. Conclusion: Establishing the correct diagnosis and initiating prompt treatment are shown to be important in achieving resolution of symptoms and in avoiding unnecessary investigations. PMID:27299063

  14. In vitro computerized evaluation of biological cardiac prosthesis calcification.

    PubMed

    Gatti, A M; Noera, G; Massini, C

    1985-01-01

    The late valvular bioprostheses failure is mainly related to leaflet calcification. This study reports a new approach to testing the biological prostheses calcification applying a computerized technique to x-ray picture. A bovine glutaraldehyde-fixed bioprostheses (BB) was implanted in two sheep in mitral position. The experimental procedure was performed on valves explanted six months after surgery. The BB x-ray pictures were tested by means of a video display computer (VDC) that can process radiographic, photographic or microscopic images and also evaluate the optical density of image quantifiable. The calcification zone assumes different values according to the calcification degree. The VDC can colour the BB x-ray images and display them on monitors (one black and white, one colour) with the colours strictly related to the grey levels of the image.

  15. Ectopic calcification in lambs from feeding the plant Cestrum diurnum.

    PubMed

    Simpson, C F; Bruss, M L

    1979-01-01

    Hypercalcemia and ectopic calcification were induced in 5 lambs by supplementing the diet with the dried leaves of the plant Cestrum diurnum, for 8 to 9 weeks. Lambs developed mineralization of blood vessels, heart, kidneys, and lungs. These tissues were examined by light and electron microscopy. In the vascular tissue there was calcification of elastic fibers in the hyperplastic intima and the media, along with mineralization of mitochondria of aortic smooth muscle cells. Myocardial cells and their mitochondria were mineralized. In the kidney, there was calcification of the epithelium of the distal convoluted tubules and collecting tubules, Bowman's capsule, and the mesangial cells of the glomeruli. In the lung, there was mineralization of the alveolar septal walls and the bronchi and bronchioles. Feeding of the calcinogenic plant to lambs caused extensive soft tissue calcification. Results of the study indicated that degeneration was the early soft tissue lesion in this plant toxicity.

  16. Calcific periarthritis of the elbow presenting as acute tennis elbow.

    PubMed

    Jawad, F; Jawad, A S M

    2014-01-01

    A 28-year-old woman presented with sudden acute lateral epicondylitis. There was no history of preceding trauma or repetitive use of the arm. Because of the acute onset and signs of acute inflammation, an X-ray was arranged. The X-ray showed a hyperdense calcified elongated globule distal to the lateral epicondyle. A diagnosis of calcific periarthritis (calcium apatite) of the elbow was made. Calcific periarthritis has rarely been reported as a cause of acute elbow pain.

  17. A review of the effect of diet on cardiovascular calcification.

    PubMed

    Nicoll, Rachel; Howard, John McLaren; Henein, Michael Y

    2015-04-21

    Cardiovascular (CV) calcification is known as sub-clinical atherosclerosis and is recognised as a predictor of CV events and mortality. As yet there is no treatment for CV calcification and conventional CV risk factors are not consistently correlated, leaving clinicians uncertain as to optimum management for these patients. For this reason, a review of studies investigating diet and serum levels of macro- and micronutrients was carried out. Although there were few human studies of macronutrients, nevertheless transfats and simple sugars should be avoided, while long chain ω-3 fats from oily fish may be protective. Among the micronutrients, an intake of 800 μg/day calcium was beneficial in those without renal disease or hyperparathyroidism, while inorganic phosphorus from food preservatives and colas may induce calcification. A high intake of magnesium (≥380 mg/day) and phylloquinone (500 μg/day) proved protective, as did a serum 25(OH)D concentration of ≥75 nmol/L. Although oxidative damage appears to be a cause of CV calcification, the antioxidant vitamins proved to be largely ineffective, while supplementation of α-tocopherol may induce calcification. Nevertheless other antioxidant compounds (epigallocatechin gallate from green tea and resveratrol from red wine) were protective. Finally, a homocysteine concentration >12 µmol/L was predictive of CV calcification, although a plasma folate concentration of >39.4 nmol/L could both lower homocysteine and protect against calcification. In terms of a dietary programme, these recommendations indicate avoiding sugar and the transfats and preservatives found in processed foods and drinks and adopting a diet high in oily fish and vegetables. The micronutrients magnesium and vitamin K may be worthy of further investigation as a treatment option for CV calcification.

  18. A Review of the Effect of Diet on Cardiovascular Calcification

    PubMed Central

    Nicoll, Rachel; Howard, John McLaren; Henein, Michael Y.

    2015-01-01

    Cardiovascular (CV) calcification is known as sub-clinical atherosclerosis and is recognised as a predictor of CV events and mortality. As yet there is no treatment for CV calcification and conventional CV risk factors are not consistently correlated, leaving clinicians uncertain as to optimum management for these patients. For this reason, a review of studies investigating diet and serum levels of macro- and micronutrients was carried out. Although there were few human studies of macronutrients, nevertheless transfats and simple sugars should be avoided, while long chain ω-3 fats from oily fish may be protective. Among the micronutrients, an intake of 800 μg/day calcium was beneficial in those without renal disease or hyperparathyroidism, while inorganic phosphorus from food preservatives and colas may induce calcification. A high intake of magnesium (≥380 mg/day) and phylloquinone (500 μg/day) proved protective, as did a serum 25(OH)D concentration of ≥75 nmol/L. Although oxidative damage appears to be a cause of CV calcification, the antioxidant vitamins proved to be largely ineffective, while supplementation of α-tocopherol may induce calcification. Nevertheless other antioxidant compounds (epigallocatechin gallate from green tea and resveratrol from red wine) were protective. Finally, a homocysteine concentration >12 µmol/L was predictive of CV calcification, although a plasma folate concentration of >39.4 nmol/L could both lower homocysteine and protect against calcification. In terms of a dietary programme, these recommendations indicate avoiding sugar and the transfats and preservatives found in processed foods and drinks and adopting a diet high in oily fish and vegetables. The micronutrients magnesium and vitamin K may be worthy of further investigation as a treatment option for CV calcification. PMID:25906474

  19. Acid-Base Balance in Uremic Rats with Vascular Calcification

    PubMed Central

    Peralta-Ramírez, Alan; Raya, Ana Isabel; Pineda, Carmen; Rodríguez, Mariano; Aguilera-Tejero, Escolástico; López, Ignacio

    2014-01-01

    Background/Aims Vascular calcification (VC), a major complication in humans and animals with chronic kidney disease (CKD), is influenced by changes in acid-base balance. The purpose of this study was to describe the acid-base balance in uremic rats with VC and to correlate the parameters that define acid-base equilibrium with VC. Methods Twenty-two rats with CKD induced by 5/6 nephrectomy (5/6 Nx) and 10 nonuremic control rats were studied. Results The 5/6 Nx rats showed extensive VC as evidenced by a high aortic calcium (9.2 ± 1.7 mg/g of tissue) and phosphorus (20.6 ± 4.9 mg/g of tissue) content. Uremic rats had an increased pH level (7.57 ± 0.03) as a consequence of both respiratory (PaCO2 = 28.4 ± 2.1 mm Hg) and, to a lesser degree, metabolic (base excess = 4.1 ± 1 mmol/l) derangements. A high positive correlation between both anion gap (AG) and strong ion difference (SID) with aortic calcium (AG: r = 0.604, p = 0.02; SID: r = 0.647, p = 0.01) and with aortic phosphorus (AG: r = 0.684, p = 0.007; SID: r = 0.785, p = 0.01) was detected. Conclusions In an experimental model of uremic rats, VC showed high positive correlation with AG and SID. PMID:25177336

  20. ADVANCE: Study to Evaluate Cinacalcet Plus Low Dose Vitamin D on Vascular Calcification in Subjects With Chronic Kidney Disease Receiving Hemodialysis

    ClinicalTrials.gov

    2014-07-14

    Chronic Kidney Disease; End Stage Renal Disease; Coronary Artery Calcification; Vascular Calcification; Calcification; Cardiovascular Disease; Chronic Renal Failure; Hyperparathyroidism; Kidney Disease; Nephrology; Secondary Hyperparathyroidism

  1. Deep-penetration photoacoustic array imaging of calcifications

    NASA Astrophysics Data System (ADS)

    Hsiao, Tsai-Chu; Cheng, Yao-Yu; Tein, Wan-Ting; Luo, Shih-Bin; Chiou, De-Yi; Chung, Ren-Jei; Li, Meng-Lin

    2013-06-01

    Calcifications are one of the most important indicators for early breast cancer detection. We explore the feasibility of deep-penetration photoacoustic (PA) imaging of calcifications based on a medical ultrasound array imaging platform. Intralipid and chicken breast phantoms embedded with different-sized hydroxyapatite (HA) particles, which are the major components of calcifications, were imaged to verify the equipment's capability and penetration depth for the visualization of calcifications. An optimal near-infrared excitation wavelength was selected to maximize PA signals of HAs, resulting in a better HA signal-to-blood ratio. We demonstrated that PA imaging is capable of visualizing 0.5-mm HA particles at a depth of 3 cm in chicken breast phantoms. The noise-equivalent penetration depth of the system for visualizing 0.5-mm HA particles in the human breast was estimated to be about 2.9 to 3.5 cm, which is clinically relevant as calcifications are usually found at a depth of 0.6 to 3.0 cm. Moreover, the feasibility of differentiating HA from blood by the PA spectroscopic technique was presented and the mechanism of the HA signal generation was discussed. The results show that PA imaging is a promising technique for real-time visualization of breast calcifications.

  2. Dual energy subtraction method for breast calcification imaging

    NASA Astrophysics Data System (ADS)

    Koukou, Vaia; Martini, Niki; Fountos, George; Michail, Christos; Sotiropoulou, Panagiota; Bakas, Athanasios; Kalyvas, Nektarios; Kandarakis, Ioannis; Speller, Robert; Nikiforidis, George

    2017-03-01

    The aim of this work was to present an experimental dual energy (DE) method for the visualization of microcalcifications (μCs). A modified radiographic X-ray tube combined with a high resolution complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. A 40/70 kV spectral combination was filtered with 100 μm cadmium (Cd) and 1000 μm copper (Cu) for the low/high-energy combination. Homogenous and inhomogeneous breast phantoms and two calcification phantoms were constructed with various calcification thicknesses, ranging from 16 to 152 μm . Contrast-to-noise ratio (CNR) was calculated from the DE subtracted images for various entrance surface doses. A calcification thickness of 152 μm was visible, with mean glandular doses (MGD) in the acceptable levels (below 3 mGy). Additional post-processing on the DE images of the inhomogeneous breast phantom resulted in a minimum visible calcification thickness of 93 μm (MGD=1.62 mGy). The proposed DE method could potentially improve calcification visibility in DE breast calcification imaging.

  3. Vascular calcification in chronic kidney disease: a clinical review.

    PubMed

    Eddington, Helen; Sinha, Smeeta; Kalra, Philip A

    2009-03-01

    Vascular calcification, which is associated with arterial stiffness, is now known to be an important predictor of cardiovascular and all-cause mortality in patients with renal disease. This calcification starts developing in the early stages of chronic kidney disease (CKD) and is present in over 50% of patients at the time of dialysis commencement. Once calcification is present it continues to progress, though some medications have been shown to slow this progression. Vascular calcification and bone abnormalities are now both encompassed by the term of CKD-mineral bone disorder and are thought to be part of the same disease process in CKD. Vascular calcification and arterial stiffness have been extensively researched in the renal population and many factors are known to be associated with their presence and progression. This calcification is an important factor to be considered in the management of the renal patient but there are different methods available for its measurement. These details will be discussed further in this review along with evidence available for management of this important complication of renal disease.

  4. Influence of Carbon on the Electrical Properties of Crustal Rocks

    SciTech Connect

    Mathez, E. A.

    2002-11-19

    The report summarizes work to determine the nature and distribution of carbon on microcracks in crystalline rocks by time-of-flight secondary ion mass spectroscopy. It also summarizes the results of a workshop devoted to investigating how carbon in rocks influences electrical conductivity and whether carbon on fracture surfaces can account for the electrical conductivity structure of the crust.

  5. Sensitivity of pelagic calcification to ocean acidification

    NASA Astrophysics Data System (ADS)

    Gangstø, R.; Joos, F.; Gehlen, M.

    2011-02-01

    Ocean acidification might reduce the ability of calcifying plankton to produce and maintain their shells of calcite, or of aragonite, the more soluble form of CaCO3. In addition to possibly large biological impacts, reduced CaCO3 production corresponds to a negative feedback on atmospheric CO2. In order to explore the sensitivity of the ocean carbon cycle to increasing concentrations of atmospheric CO2, we use the new biogeochemical Bern3D/PISCES model. The model reproduces the large scale distributions of biogeochemical tracers. With a range of sensitivity studies, we explore the effect of (i) using different parameterizations of CaCO3 production fitted to available laboratory and field experiments, of (ii) letting calcite and aragonite be produced by auto- and heterotrophic plankton groups, and of (iii) using carbon emissions from the range of the most recent IPCC Representative Concentration Pathways (RCP). Under a high-emission scenario, the CaCO3 production of all the model versions decreases from ~1 Pg C yr-1 to between 0.36 and 0.82 Pg C yr-1 by the year 2100. The changes in CaCO3 production and dissolution resulting from ocean acidification provide only a small feedback on atmospheric CO2 of -1 to -11 ppm by the year 2100, despite the wide range of parameterizations, model versions and scenarios included in our study. A potential upper limit of the CO2-calcification/dissolution feedback of -30 ppm by the year 2100 is computed by setting calcification to zero after 2000 in a high 21st century emission scenario. The similarity of feedback estimates yielded by the model version with calcite produced by nanophytoplankton and the one with calcite, respectively aragonite produced by mesozooplankton suggests that expending biogeochemical models to calcifying zooplankton might not be needed to simulate biogeochemical impacts on the marine carbonate cycle. The changes in saturation state confirm previous studies indicating that future anthropogenic CO2 emissions may

  6. Influence of wheat kernel physical properties on the pulverizing process.

    PubMed

    Dziki, Dariusz; Cacak-Pietrzak, Grażyna; Miś, Antoni; Jończyk, Krzysztof; Gawlik-Dziki, Urszula

    2014-10-01

    The physical properties of wheat kernel were determined and related to pulverizing performance by correlation analysis. Nineteen samples of wheat cultivars about similar level of protein content (11.2-12.8 % w.b.) and obtained from organic farming system were used for analysis. The kernel (moisture content 10 % w.b.) was pulverized by using the laboratory hammer mill equipped with round holes 1.0 mm screen. The specific grinding energy ranged from 120 kJkg(-1) to 159 kJkg(-1). On the basis of data obtained many of significant correlations (p < 0.05) were found between wheat kernel physical properties and pulverizing process of wheat kernel, especially wheat kernel hardness index (obtained on the basis of Single Kernel Characterization System) and vitreousness significantly and positively correlated with the grinding energy indices and the mass fraction of coarse particles (> 0.5 mm). Among the kernel mechanical properties determined on the basis of uniaxial compression test only the rapture force was correlated with the impact grinding results. The results showed also positive and significant relationships between kernel ash content and grinding energy requirements. On the basis of wheat physical properties the multiple linear regression was proposed for predicting the average particle size of pulverized kernel.

  7. Mechanical properties that influence antimicrobial peptide activity in lipid membranes.

    PubMed

    Marín-Medina, Nathaly; Ramírez, Diego Alejandro; Trier, Steve; Leidy, Chad

    2016-12-01

    Antimicrobial peptides are small amphiphilic proteins found in animals and plants as essential components of the innate immune system and whose function is to control bacterial infectious activity. In order to accomplish their function, antimicrobial peptides use different mechanisms of action which have been deeply studied in view of their potential exploitation to treat antibiotic-resistant bacterial infections. One of the main mechanisms of action of these peptides is the disruption of the bacterial membrane through pore formation, which, in some cases, takes place via a monomer to oligomer cooperative transition. Previous studies have shown that lipid composition, and the presence of exogenous components, such as cholesterol in model membranes or carotenoids in bacteria, can affect the potency of distinct antimicrobial peptides. At the same time, considering the membrane as a two-dimensional material, it has been shown that membrane composition defines its mechanical properties which might be relevant in many membrane-related processes. Nevertheless, the correlation between the mechanical properties of the membrane and antimicrobial peptide potency has not been considered according to the importance it deserves. The relevance of these mechanical properties in membrane deformation due to peptide insertion is reviewed here for different types of pores in order to elucidate if indeed membrane composition affects antimicrobial peptide activity by modulation of the mechanical properties of the membrane. This would also provide a better understanding of the mechanisms used by bacteria to overcome antimicrobial peptide activity.

  8. Flax Fiber Quality and Influence on Interfacial Properties of Composites.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measured flax physical and chemical properties could potentially impact binding and thus the stress transfer between the matrix and fiber. The study included 14 linseed samples with 12 samples ranging in cleanliness and retting produced using hammer mill technology from 2000, 2006 and 2007 with 2 sa...

  9. Influence of isopropanol on ferroelectric properties of triglycine sulfate crystals

    NASA Astrophysics Data System (ADS)

    Milovidova, S. D.; Rogazinskaya, O. V.; Sidorkin, A. S.; Nguen, Kh. T.; Bykova, A. V.

    2015-03-01

    The dielectric and switching properties of triglycine sulfate (TGS) crystals grown from aqua solution with isopropanol have been studied. It has been shown that their behavior has common features with the behavior of the TGS crystals irradiated by X-rays, and also with the TGS crystals doped with L, α-alanine.

  10. Magnesium modulates the expression levels of calcification-associated factors to inhibit calcification in a time-dependent manner.

    PubMed

    Xu, Jinsheng; Bai, Yaling; Jin, Jingjing; Zhang, Junxia; Zhang, Shenglei; Cui, Liwen; Zhang, Huiran

    2015-03-01

    Vascular calcification, a common complication in patients with chronic kidney disease, involves a variety of mechanisms associated with the regulation of calcification-associated factors. Previous clinical studies have indicated that magnesium is involved in the reduction of vascular calcification; however, the mechanism underlying this process remains unknown. The aim of the present study was to investigate the effects of magnesium on β-glycerophosphate (β-GP)-induced calcification and the underlying mechanisms. Primary rat vascular smooth muscle cells (VSMCs) were exposed to 10 mM β-GP in medium with or without the addition of 3 mM magnesium or 2-aminoethoxy-diphenylborate (2-APB; an inhibitor of magnesium transport), for a 14-day period. Calcium deposition and alkaline phosphatase (ALP) activity were measured by Alizarin red staining, quantification of calcium and enzyme-linked immunosorbent assay. The expression levels of core-binding factor α-1 (Cbfα1), matrix Gla protein (MGP) and osteopontin (OPN) were determined by reverse transcription-polymerase chain reaction or western blot analysis, following incubation for 0, 3, 6, 10 and 14 days with the different media. VSMC calcification and ALP activity was reduced significantly in the high-magnesium medium compared with the calcification medium, during the 14-day incubation. The magnesium-induced changes in the VSMCs included a β-GP-induced downregulation of Cbfα1 by day 3 of incubation, an effect that was gradually enhanced over the 14-day period. By contrast, magnesium produced notable increases in MGP and OPN expression levels, with an opposite pattern to that observed in the Cbfα1 expression levels. However, the addition of 2-APB appeared to inhibit the protective effect of magnesium on the VSMCs. Therefore, magnesium was able to effectively reduce β-GP-induced calcification in rat VSMCs by regulating the expression levels of calcification-associated factors in a time-dependent manner.

  11. Fiber properties and their influence on paper structure

    NASA Astrophysics Data System (ADS)

    Turrado Saucedo, Jose; Ramirez P., R.; Perez R., S.

    1997-08-01

    When we move our considerations of the components of paper, through the manufacture of paper, to the use of paper, we are analyzing the fundamental properties of paper related to its end uses. Paper as a product has a lot of possible uses and they are increasing, nevertheless it is very important in secondary products like corrugated board, etc. Every year the paper world production has an increase of approximately 1.6%. For the year 1994 it was 268,772,000 tons and during 1995 this production was 277,791,000 t. In Mexico for instance in 1994/2,860,162 tons and 1995/3,047,153 tons plus paper importation is possible to reach a per capita consumption of 35.8 kg. All paper quality kinds demand some special paper properties, which require technology, human resources and fibers properties. Surely there are fields to investigate by comparing the fundamental properties of paper and board with those of other materials, that is the reason why research must be done, despite the recent difficult times. In hard times its done distinction on switch of founds from fundamental to applied research and research for immediate development, this is understandable. Nevertheless, to study the relation between fibers and end use performance could well capture and even create a yet unknown market. Rather than adopt the attitude that 'here is paper, let us find markets for it' such research into the fundamental properties of the product will give one a clearer understanding of how it can satisfy future demands and meet possible future specifications. Because it is in meeting these specifications that the future of the industry must depend, it must be clear that money spent in this way now may not produce immediate quantifiable benefits, but it will produce the essential reserves that will in future be turned to good account by the industry.

  12. Influence of osmolarity on the optical properties of human erythrocytes

    NASA Astrophysics Data System (ADS)

    Friebel, Moritz; Helfmann, Jürgen; Meinke, Martina C.

    2010-09-01

    Plasma osmolarity influences the volume and shape of red blood cells (RBCs). The volume change is inversely related to the hemoglobin concentration and as a consequence to the complex refractive index within the cell. These morphological changes can be linked to changes in the optical behavior of the cells. The optical parameters, absorption coefficient μa, scattering coefficient μs, and effective scattering phase function of red blood cells are investigated in dependence on osmolarity in the spectral range from 250 to 1100 nm. Integrating sphere measurements of light transmittance and reflectance in combination with inverse Monte-Carlo simulations are carried out for osmolarities from 225 to 400 mosmol/L. Osmolarity changes have a significant influence on the optical parameters, which can in part be explained by changes in the complex refractive index, cell shape, and cell volume. Spherical forms of RBCs induced by low osmolarity show reduced scattering effects compared to the normal RBC biconcave disk shape. Spinocytes, which are crenated erythrocytes induced by high osmolarity, show the highest scattering effects. Even only a 10% change in osmolarity has a drastic influence on the optical parameters, which appears to be of the same order as for 10% hematocrit and oxygen saturation changes.

  13. Affective stimulus properties influence size perception and the Ebbinghaus illusion

    PubMed Central

    Semin, Gün R.; Oudejans, Raôul R. D.; Beek, Peter J.

    2007-01-01

    In the New Look literature of the 1950s, it has been suggested that size judgments are dependent on the affective content of stimuli. This suggestion, however, has been ‘discredited’ due to contradictory findings and methodological problems. In the present study, we revisited this forgotten issue in two experiments. The first experiment investigated the influence of affective content on size perception by examining judgments of the size of target circles with and without affectively loaded (i.e., positive, neutral, and negative) pictures. Circles with a picture were estimated to be smaller than circles without a picture, and circles with a negative picture were estimated to be larger than circles with a positive or a neutral picture confirming the suggestion from the 1950s that size perception is influenced by affective content, an effect notably confined to negatively loaded stimuli. In a second experiment, we examined whether affective content influenced the Ebbinghaus illusion. Participants judged the size of a target circle whereby target and flanker circles differed in affective loading. The results replicated the first experiment. Additionally, the Ebbinghaus illusion was shown to be weakest for a negatively loaded target with positively loaded and blank flankers. A plausible explanation for both sets of experimental findings is that negatively loaded stimuli are more attention demanding than positively loaded or neutral stimuli. PMID:17410379

  14. Influence of osmolarity on the optical properties of human erythrocytes.

    PubMed

    Friebel, Moritz; Helfmann, Jürgen; Meinke, Martina C

    2010-01-01

    Plasma osmolarity influences the volume and shape of red blood cells (RBCs). The volume change is inversely related to the hemoglobin concentration and as a consequence to the complex refractive index within the cell. These morphological changes can be linked to changes in the optical behavior of the cells. The optical parameters, absorption coefficient μa, scattering coefficient μs, and effective scattering phase function of red blood cells are investigated in dependence on osmolarity in the spectral range from 250 to 1100 nm. Integrating sphere measurements of light transmittance and reflectance in combination with inverse Monte-Carlo simulations are carried out for osmolarities from 225 to 400 mosmol/L. Osmolarity changes have a significant influence on the optical parameters, which can in part be explained by changes in the complex refractive index, cell shape, and cell volume. Spherical forms of RBCs induced by low osmolarity show reduced scattering effects compared to the normal RBC biconcave disk shape. Spinocytes, which are crenated erythrocytes induced by high osmolarity, show the highest scattering effects. Even only a 10% change in osmolarity has a drastic influence on the optical parameters, which appears to be of the same order as for 10% hematocrit and oxygen saturation changes.

  15. Vascular Calcification and Renal Bone Disorders

    PubMed Central

    Lu, Kuo-Cheng; Wu, Chia-Chao; Yen, Jen-Fen; Liu, Wen-Chih

    2014-01-01

    At the early stage of chronic kidney disease (CKD), the systemic mineral metabolism and bone composition start to change. This alteration is known as chronic kidney disease-mineral bone disorder (CKD-MBD). It is well known that the bone turnover disorder is the most common complication of CKD-MBD. Besides, CKD patients usually suffer from vascular calcification (VC), which is highly associated with mortality. Many factors regulate the VC mechanism, which include imbalances in serum calcium and phosphate, systemic inflammation, RANK/RANKL/OPG triad, aldosterone, microRNAs, osteogenic transdifferentiation, and effects of vitamins. These factors have roles in both promoting and inhibiting VC. Patients with CKD usually have bone turnover problems. Patients with high bone turnover have increase of calcium and phosphate release from the bone. By contrast, when bone turnover is low, serum calcium and phosphate levels are frequently maintained at high levels because the reservoir functions of bone decrease. Both of these conditions will increase the possibility of VC. In addition, the calcified vessel may secrete FGF23 and Wnt inhibitors such as sclerostin, DKK-1, and secreted frizzled-related protein to prevent further VC. However, all of them may fight back the inhibition of bone formation resulting in fragile bone. There are several ways to treat VC depending on the bone turnover status of the individual. The main goals of therapy are to maintain normal bone turnover and protect against VC. PMID:25136676

  16. Elastin Calcification and its Prevention with Aluminum Chloride Pretreatment

    PubMed Central

    Vyavahare, Narendra; Ogle, Matthew; Schoen, Frederick J.; Levy, Robert J.

    1999-01-01

    Elastin, an abundant structural protein present in the arterial wall, is prone to calcification in a number of disease processes including porcine bioprosthetic heart valve calcification and atherosclerosis. The mechanisms of elastin calcification are not completely elucidated. In the present work, we demonstrated calcification of purified elastin in rat subdermal implants (Ca2+ = 89.73 ± 9.84 μg/mg after 21 days versus control, unimplanted Ca2+ = 0.16 ± 0.04 μg/mg). X-ray diffraction analysis along with resolution enhanced FTIR spectroscopy demonstrated the mineral phase to be a poorly crystalline hydroxyapatite. We investigated the time course of calcification, the effect of glutaraldehyde crosslinking on calcification, and mechanisms of inhibition of elastin calcification by pretreatment with aluminum chloride (AlCl3). Glutaraldehyde pretreatment did not affect calcification (Ca2+ = 89.06 ± 17.93 μg/mg for glutaraldehyde crosslinked elastin versus Ca2+ = 89.73 ± 9.84 μg/mg for uncrosslinked elastin). This may be explained by radioactive (3H) glutaraldehyde studies showing very low reactivity between glutaraldehyde and elastin. Our results further demonstrated that AlCl3 pretreatment of elastin led to complete inhibition of elastin calcification using 21-day rat subdermal implants, irrespective of glutaraldehyde crosslinking (Ca2+ = 0.73–2.15 μg/mg for AlCl3 pretreated elastin versus 89.73 ± 9.84 for untreated elastin). The AlCl3 pretreatment caused irreversible binding of aluminum ions to elastin, as assessed by atomic emission spectroscopy. Moreover, aluminum ion binding altered the spatial configuration of elastin as shown by circular dichroism (CD), Fourier transform infrared (FTIR), and 13C nuclear magnetic resonance (NMR) spectroscopy studies, suggesting a net structural change including a reduction in the extent of β sheet structures and an increase in coil-turn conformations. Thus, it is concluded that purified elastin calcifies in rat

  17. Effects of Ultrasound Therapy on Calcificated Tendinitis of the Shoulder

    PubMed Central

    Takatori, Katsuhiko; Morishita, Shinichiro; Nagino, Koji; Yamamoto, Waka; Shimohira, Takahiro; Shimada, Tomoaki

    2002-01-01

    In general, surgery is recommended for calcificated tendinitis of the shoulder if the patients have symptoms after conservative treatments, including needle aspiration and physical therapy. Many researchers agree about the need for adequate physical therapy consisting of range of motion exercise, muscle strengthening exercises and electrophysical agents. Some researchers report that ultrasound (u/s) promotes angiogenesis and calcium uptake to fibroblasts, but there are few studies about u/s effects on calcificated tendinitis of the shoulder. The purpose of this study was to evaluate the u/s therapy effect on calcification, pain during active movement, and to identify factors related to improvement in a randomized controlled fashion. We used the stratified random allocation method to assign 40 consecutive patients to experimental and control groups, so each group consisted of 20 patients. The experimental group was treated by u/s therapy and therapeutic exercises, and the control group was treated with therapeutic exercises only. All patients in both groups came to our department 3 times per week and u/s therapy was performed 3 times per week until the end of the study. First, we classified the calcifications as type I (clearly circumscribed and with dense appearance on radiography), type II (dense or clearly circumscribed appearance) and type III (translucent or cloudy appearance without clear circumscription) according to the classification of Gartner and Heyer. Radiography was performed every one month, and the main outcome measure was the change from the base-line of the calcification on radiography at the end of the treatment. The three point scale of Gartner and Heyer was used, in which a score of 1 indicates no change or a worsening of the condition, a score of 2 a decrease of at least 50 percent in the area and density of the calcification, and a score of 3 a complete resolution of the calcification. We also examined the affected shoulders for presence or

  18. Influence of Barium Hexaferrite on Magnetic Properties of Hydroxyapatite Ceramics.

    PubMed

    Jarupoom, P; Jaita, P

    2015-11-01

    Hydroxyapatite (HA) powders was derived from natural bovine bone by sequence of thermal processes. The barium hexaferrite (BF) find magnetic powders were added into HA powders in ratio of 1-3 vol.%. The HA-BF ceramics were prepared by a solid state reaction method and sintered at 1250 degrees C for 2 h. Effects of BF additive on structural, physical and magnetic properties of HA ceramics were investigated. X-ray diffraction revealed that all HA-BF samples showed a main phase of high purity hydroxyapatite [Ca10(PO4)6(OH)2] with calcium and phosphate molar ratio of 1.67. The addition of BF into HA inhibited grain growth and caused an improvement of mechanical properties. The M-H hysteresis loops also showed an improvement in magnetic behavior for higher content of BF. Moreover, in vitro bioactivity test indicated that the 2-3 vol.% sample may be suitable for biological applications.

  19. Influence of saturation properties on shell-model calculations

    NASA Astrophysics Data System (ADS)

    Abzouzi, A.; Caurier, E.; Zuker, A. P.

    1991-03-01

    It is shown that the nuclear Hamiltonian scrH separates rigorously into a monopole field scrHm and a multipole part scrHm. scrHm is entirely responsible for saturation properties and can be treated phenomenologically with few parameters. When realistic interactions are used for scrHM in regions from the p shell to the N=82 isotones, shell-model calculations yield excellent spectroscopy and demand nuclear radii very close to the observed ones.

  20. Process design of press hardening with gradient material property influence

    SciTech Connect

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-04

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  1. Influence of clearing solutions osmolarity on the optical properties of RBC

    NASA Astrophysics Data System (ADS)

    Zhestkov, Dmitry M.; Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.

    2004-08-01

    The possibility of immersion clearing of human blood in visible and NIR spectral range has been discussed. Based on presented model the spectral behavior of scattering and absorption characteristics of blood caused by immersion properties of glucose solution has been analyzed. The influence of osmotic properties of glucose solution on blood erythrocytes has been shown.

  2. The Fabric of Thought: Priming Tactile Properties during Reading Influences Direct Tactile Perception

    ERIC Educational Resources Information Center

    Brunye, Tad T.; Walters, Eliza K.; Ditman, Tali; Gagnon, Stephanie A.; Mahoney, Caroline R.; Taylor, Holly A.

    2012-01-01

    The present studies examined whether implied tactile properties during language comprehension influence subsequent direct tactile perception, and the specificity of any such effects. Participants read sentences that implicitly conveyed information regarding tactile properties (e.g., "Grace tried on a pair of thick corduroy pants while…

  3. Influence of dispersion medium on properties of complex lithium greases

    SciTech Connect

    Bulgak, V.B.; Cherednichenko, G.I.; Sokolova, T.G.; Voznyuk, F.Z.

    1984-03-01

    This article investigates the properties of complex lithium (cLi) greases prepared by thickening various dispersion media, differing in hydrocarbon composition, with cLi soap (10% by weight). Distillate and residual oils produced in the USSR were used as the dispersion media. It is determined that the viscosity level of the dispersion medium does not determine the properties of the cLi greases. The presence of aromatic hydrocarbons in the distillate oils, as the content of aromatics is increased, tends to increase the viscosity-strength characteristics, increase the colloidal stability (lower the oil bleeding), reduce the heat-hardening, and give lower values of the viscosity-temperature characteristics of the greases. The quality of cLi greases based on distillate oils depends to a considerable degree on the hydrocarbon group composition of the oil and on the hydrocarbon structure. The greases based on residual oils have better rheological properties and serviceability at high temperatures than the greases based on distillate oils. It is recommended that residual oils be used as the dispersion medium for cLi greases operating at high temperatures. Includes 3 tables.

  4. The influence of additives on rheological properties of limestone slurry

    NASA Astrophysics Data System (ADS)

    Jaworska, B.; Bartosik, A.

    2014-08-01

    Limestone slurry appears in the lime production process as the result of rinsing the processed material. It consists of particles with diameter smaller than 2 mm and the water that is a carrier of solid fraction. Slurry is directed to the settling tank, where the solid phase sediments and the excess water through the transfer system is recovered for re-circulation. Collected at the bottom of the tank sludge is deposited in a landfill located on the premises. Rheological properties of limestone slurry hinder its further free transport in the pipeline due to generated flow resistance. To improve this state of affairs, chemical treatment of drilling fluid, could be applied, of which the main task is to give the slurry properties suitable for the conditions encountered in hydrotransport. This treatment consists of applying chemical additives to slurry in sufficient quantity. Such additives are called as deflocculants or thinners or dispersants, and are chemical compounds which added to aqueous solution are intended to push away suspended particles from each other. The paper presents the results of research allowing reduction of shear stress in limestone slurry. Results demonstrate rheological properties of limestone slurry with and without the addition of modified substances which causes decrease of slurry viscosity, and as a consequence slurry shear stress for adopted shear rate. Achieving the desired effects increases the degree of dispersion of the solid phase suspended in the carrier liquid and improving its ability to smooth flow with decreased friction.

  5. Influence of oxygen on the optical properties of silver nanoparticles.

    PubMed

    Renteria-Tapia, V M; García-Macedo, J

    2008-12-01

    Silver nanoparticles in sol-gel silica films were obtained by annealing in hydrogen atmosphere and subsequently in oxygen atmosphere. Their properties were measured by UV-vis spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electronic microscopy (HRTEM) and X-ray diffraction analysis. Samples prepared in a reducing atmosphere exhibited a surface plasmon resonance (SPR) located at 399 nm. Silver nanoparticles in an oxidizing atmosphere exhibited a red shift and damping of the SPR. These optical properties were explained due to the oxidation on the surface of silver nanoparticles to silver oxide yield in an oxygen atmosphere. Silver core-silver oxide shell nanostructures were observed by HRTEM. The average size of the metallic nanoparticles obtained by TEM was used for modeling the UV-vis spectra by using the Gans theory. Good fits to the spectra under an oxidizing atmosphere were obtained considering variable refractive indexes coming from the silver oxide shells surrounding to the nanoparticles. Therefore, the interaction between oxygen and the metallic surface of the nanoparticles, sensitively alters their optical properties.

  6. Properties Influencing Plasma Discharges in Packed Bed Reactors

    NASA Astrophysics Data System (ADS)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for CO2 removal and conversion of waste gases into higher value compounds. We report on results of a computational investigation of PBR-DBD properties using the plasma hydrodynamics simulator nonPDPSIM with a comparison to experiments. Dielectric beads (rods in 2D) were inserted between two coplanar electrodes, 1 cm apart filled by humid air. A step-pulse of -30 kV was applied to the top electrode. Material properties of the beads (dielectric constant, secondary emission coefficient) and gas properties (photoionization and photo-absorption cross-sections, temperature) were varied. We found that photoionization plays a critical role in the propagation of the discharge through the PBR, as it serves to seed charges in regions of high electric field. Increasing rates of photo-ionization enable increases in the discharge propagation velocity, ionization rates and production of radicals. A transition between DBD-like and arc-like discharges occurs as the radiation mean free path decreases. Increasing the dielectric constant of the beads increased electric fields in the gas, which translated to increased discharge propagation velocity and charge density until ɛ/ɛ0 100. Secondary electron emission coefficient and gas temperature have minimal impacts on the discharge propagation though the latter did affect the production of reactive species. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  7. Influence of delayed pouring on irreversible hydrocolloid properties.

    PubMed

    Rodrigues, Stéfani Becker; Augusto, Carolina Rocha; Leitune, Vicente Castelo Branco; Samuel, Susana Maria Werner; Collares, Fabrício Mezzomo

    2012-01-01

    The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex); Hydrogum (Zhermack); Hydrogum 5 (Zhermack); and Hydro Print Premium (Coltene). Their physical properties, including the recovery from deformation (n = 3), compressive strength (n = 3), and detail reproduction and gypsum compatibility (n = 3), were analyzed according to ANSI/ADA specification no. 18. Specimens were stored at 23ºC and humidity and were then poured with gypsum immediately and after 1, 2, 3, 4, and 5 days. The data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test at p < 0.05. All of the alginate impression materials tested exhibited detail reproduction and gypsum compatibility at all times. Hydro Print Premium and Hydrogum 5 showed recovery from deformation, as established by ANSI/ADA specification no. 18, after 5 days of storage. As the storage time increased, the compressive strength values also increased. Considering the properties of compounds' recovery from deformation, compressive strength, and detail reproduction and gypsum compatibility, irreversible hydrocolloids should be poured immediately.

  8. Influence of Through-Thickness Pinning on Composite Shear Properties

    NASA Astrophysics Data System (ADS)

    Maurin, Romain; Baley, Christophe; Cartié, Denis D. R.; Davies, Peter

    2012-12-01

    This paper describes results from tests to examine the influence of through-thickness pinning on in-plane shear behaviour, measured by tensile loading of ±45° specimens. Samples were produced by both aeronautical and marine manufacturing processes. As few previous studies have investigated pinning of marine composites these were also subjected to out-of-plane shear delamination tests. For both carbon/epoxy laminates the pins reduce the apparent in-plane shear modulus and strength. Pins modify the strain field measured by full-field image analysis, and slow damage development. A new damage mechanism, transverse pin cracking, was observed.

  9. [Vascular Calcification - Pathological Mechanism and Clinical Application - . The effect of cinacalcet on vascular calcification].

    PubMed

    Yokoyama, Keitaro

    2015-05-01

    Cinacalcet acts on calcium receptors (CaR) expressed on chief cells of the parathyroid gland to inhibit the secretion of parathyroid hormone (PTH) . This drug inhibits PTH secretion without causing an elevation of serum calcium and phosphorus, unlike active vitamin D. Several experimental studies demonstrated an inhibitory effect of calcimimetics on the progression of vascular calcification in animals with chronic kidney disease (CKD), in keeping with the expression of the calcium-sensing receptor (CaSR) in vascular tissue. The EVOLVE, evaluated in patients with CKD 5D the effects of the cinacalcet on the progression of vascular calcification and hard cardiovascular outcomes, respectively. The EVOLVE trials missed their respective primary end point by intent-to-treat analysis. However, recently, in order to define the frequency of fatal and nonfatal cardiovascular events attributable to atherosclerotic and nonatherosclerotic mechanisms, risk factors for these events, and the effects of cinacalcet, post hoc analysis using adjudicated data collected during the EVOLVE Trial were perfomed. In this trial, combining fatal and nonfatal cardiovascular events, randomization to cinacalcet reduced the rates of sudden death and heart failure. Patients randomized to cinacalcet experienced fewer nonatherosclerotic cardiovascular events, while the effect of cinacalcet on atherosclerotic events did not reach statistical significance.

  10. Shunt tube calcification as a late complication of ventriculoperitoneal shunting

    PubMed Central

    Salim, Abubakr Darrag; Elzain, Mohammed Awad; Mohamed, Haddab Ahmed; Ibrahim Zayan, Baha Eldin Mohamed

    2015-01-01

    Shunt calcification is a rare complication of ventriculoperitoneal shunting that occurs years later after the initial operation this condition is rarely reported in literature. Two patients with shunt calcifications were described. The first patient was 17-year-old lady who had congenital hydrocephalus and shunted in the early infancy, she was presented recently complaining of itching of the skin along the shunt track and limitation of neck movement. The patient was then operated with removal of the old peritoneal catheter and replacing it with a new one. The second patient was 17-year-old boy originally was a case of posterior fossa pilocytic astrocytoma associated with obstructive hydrocephalus, he was operated with both shunting for the hydrocephalus and tumor removal, 6 years later he presented with shunt exposure. Calcification of the shunt tube was discovered intraoperatively upon shunt removal. Shunt calcification has been observed mainly in barium-impregnated catheters. Introducing plain silicone-coated shunt tubing may reduce the rate of this condition. The usual complaints of the patients suffering from this condition are pain in the neck and chest wall along the shunt pathway and limitation of the neck movement due to shunt tube tethering, but features of shunt dysfunction and skin irritation above the shunt may be present. In this review, plain X-ray and operative findings showed that the most extensive calcification is present in the neck, where the catheters were subject to heavy mechanical stress. Disturbed calcium and phosphate metabolisms may be involved in this condition. Shunt calcification is a rare condition that occurs due to material aging presenting with features of shunt tethering, dysfunction or overlying skin irritation. Plain X-ray is needed to detect calcification while shunt removal, replacement or endoscopic third ventriculostomy may carry solution for this condition. PMID:26396620

  11. The association of breast arterial calcification and metabolic syndrome

    PubMed Central

    Yildiz, Seyma; Toprak, Huseyin; Aydin, Sinem; Bilgin, Mehmet; Oktay, Veysel; Abaci, Okay; Kocas, Cuneyt

    2014-01-01

    OBJECTIVES: We investigated the relationship between metabolic syndrome and breast arterial calcification detected via mammography in a cohort of postmenopausal subjects. METHODS: Among 837 patients referred to our radiology department for mammographic screening, 310 postmenopausal females (105 patients with and 205 patients without breast arterial calcification) aged 40 to 73 (mean 55.9±8.4) years were included in this study. The groups were compared with respect to clinical characteristics and metabolic syndrome criteria. Univariate and multivariate analyses identified the factors related to breast arterial calcification. RESULTS: Age, postmenopausal duration and the frequencies of diabetes mellitus, hypertension and metabolic syndrome were significantly higher in the subjects with breast arterial calcification than in those without (p<0.05). Multivariate analysis indicated that age (OR = 1.3, 95% CI = 1.1–1.6, p = 0.001) and metabolic syndrome (OR = 4.0, 95% CI = 1.5−10.4, p = 0.005) were independent predictors of breast arterial calcification detected via mammography. The independent predictors among the features of metabolic syndrome were low levels of high-density lipoproteins (OR = 8.1, 95% CI = 1.0−64.0, p = 0.047) and high blood pressure (OR = 8.7, 95% CI = 1.5−49.7, p = 0.014). CONCLUSIONS: The likelihood of mammographic detection of breast arterial calcification increases with age and in the presence of hypertension or metabolic syndrome. For patients undergoing screening mammography who present with breast arterial calcification, the possibility of metabolic syndrome should be considered. These patients should be informed of their cardiovascular risk factors and counseled on appropriate lifestyle changes. PMID:25627997

  12. Shunt tube calcification as a late complication of ventriculoperitoneal shunting.

    PubMed

    Salim, Abubakr Darrag; Elzain, Mohammed Awad; Mohamed, Haddab Ahmed; Ibrahim Zayan, Baha Eldin Mohamed

    2015-01-01

    Shunt calcification is a rare complication of ventriculoperitoneal shunting that occurs years later after the initial operation this condition is rarely reported in literature. Two patients with shunt calcifications were described. The first patient was 17-year-old lady who had congenital hydrocephalus and shunted in the early infancy, she was presented recently complaining of itching of the skin along the shunt track and limitation of neck movement. The patient was then operated with removal of the old peritoneal catheter and replacing it with a new one. The second patient was 17-year-old boy originally was a case of posterior fossa pilocytic astrocytoma associated with obstructive hydrocephalus, he was operated with both shunting for the hydrocephalus and tumor removal, 6 years later he presented with shunt exposure. Calcification of the shunt tube was discovered intraoperatively upon shunt removal. Shunt calcification has been observed mainly in barium-impregnated catheters. Introducing plain silicone-coated shunt tubing may reduce the rate of this condition. The usual complaints of the patients suffering from this condition are pain in the neck and chest wall along the shunt pathway and limitation of the neck movement due to shunt tube tethering, but features of shunt dysfunction and skin irritation above the shunt may be present. In this review, plain X-ray and operative findings showed that the most extensive calcification is present in the neck, where the catheters were subject to heavy mechanical stress. Disturbed calcium and phosphate metabolisms may be involved in this condition. Shunt calcification is a rare condition that occurs due to material aging presenting with features of shunt tethering, dysfunction or overlying skin irritation. Plain X-ray is needed to detect calcification while shunt removal, replacement or endoscopic third ventriculostomy may carry solution for this condition.

  13. Influence of finishing on the electrochemical properties of dental alloys.

    PubMed

    Kaneko, T; Hattori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

    2000-05-01

    Dental alloy surface finishing procedures of may influence their electrochemical behavior, which is used to evaluate their corrosion resistance. We examined the polarization resistance and potentiodynamic polarization profile of the precious-metal alloys, Type 4 gold alloy and silver-palladium alloy, and the base-metal alloys, nickel-chromium alloy, cobalt-chromium alloy, and CP-titanium. Three types of finishing procedure were examined: mirror-finishing using 0.05 micron alumina particles, polishing using #600 abrasive paper and sandblasting. Dissolution of the alloy elements in 0.9% NaCl solution was also measured and compared with the electrochemical evaluation. The corrosion resistance of the dental alloys was found to relate to finishing as follows: The polarization resistance and potentiodynamic polarization behavior revealed that the corrosion resistance improved in the order of sandblasting, #600-abrasive-paper polishing, and mirror-finishing. While the corrosion potential, critical current density and passive current density varied depending on the type of finishing, the transpassive potential remained unchanged. The influence of finishing on the corrosion resistance of precious-metal alloys was less significant than on that of base-metal alloys. A mirror-finishing specimen was recommended for use in evaluation of the corrosion resistance of various dental alloys.

  14. Effect of the social influence on topological properties of user-object bipartite networks

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Guo; Hu, Zhaolong; Guo, Qiang

    2013-11-01

    Social influence plays an important role in analyzing online users' collective behaviors [Salganik et al., Science 311, 854 (2006)]. However, the effect of the social influence from the viewpoint of theoretical model is missing. In this paper, by taking into account the social influence and users' preferences, we develop a theoretical model to analyze the topological properties of user-object bipartite networks, including the degree distribution, average nearest neighbor degree and the bipartite clustering coefficient, as well as topological properties of the original user-object networks and their unipartite projections. According to the users' preferences and the global ranking effect, we analyze the theoretical results for two benchmark data sets, Amazon and Bookcrossing, which are approximately consistent with the empirical results. This work suggests that this model is feasible to analyze topological properties of bipartite networks in terms of the social influence and the users' preferences.

  15. Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

    PubMed

    Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

    2013-11-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

  16. Properties that Influence the Specific Surface Areas of Carbon Nanotubes and Nanofibers

    PubMed Central

    BIRCH, M. EILEEN; RUDA-EBERENZ, TONI A.; CHAI, MING; ANDREWS, RONNEE; HATFIELD, RANDAL L.

    2015-01-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer–Emmett–Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed. PMID:24029925

  17. Influence of snow properties on dense avalanche friction parameters

    NASA Astrophysics Data System (ADS)

    Mohamed, Naaim

    2013-04-01

    The values of the Voellmy friction parameters of 735 historical avalanches that occurred along 26 paths in the Chamonix valley since 1958 are back-analysed with a depth-averaged hydraulic model including sub models for erosion, entrainment and deposition. For each path, the longitudinal and crosswise topographic profiles were derived from a high resolution digital elevation model acquired by laser scanning. The initial snow depth and snow cohesion, as well as various physical properties of snow, were computed from numerical simulations of the detailed snowpack model Crocus fed by the SAFRAN meteorological analysis. For each event, the full ranges of the two friction parameters were scanned and the pairs of friction parameters for which the run-out altitude is found close enough to the observed one (with an uncertainty of 5m), were retained. Statistical class analysis was used to investigate the correlation between the obtained friction coefficients and the snow physical properties. Concerning the inertial friction coefficient, no evident trend with the snow parameters was found. For the static friction coefficient, an increasing trend with the temperature and the density was observed, as well as a decreasing trend with the liquid water content and the initial snow depth.

  18. Influence of deuterium implantation on bubble garnet properties

    SciTech Connect

    Gerard, P.; Capra, T.; Magnin, J.

    1985-12-15

    A classical (Y Sm Lu Ca)/sub 3/ (Fe Ge)/sub 5/ O/sub 12/ bubble garnet, supporting 1.8-..mu..m bubbles, has been implanted with 1.5 x 10/sup 16/ D/sup +//sub 2/ cm/sup 2/ at 60 keV either directly or through a predeposited 100-A-thick silica layer. Nuclear techniques such as D (/sup 3/He, ..cap alpha..) p nuclear reaction and Rutherford backscattering combined with channeling measurements were used to determine the implant and damage profiles, respectively. Double-crystal x-ray diffraction was used to measure the maximum strain and magnetic properties were obtained from ferromagnetic resonance. The evolution of these parameters has been studied as a function of annealing treatments. It follows that, as compared to hydrogen, deuterium also interacts at damage-level inducing within the garnet new magnetic phenomena. A higher annealing temperature is required for bubble memory applications. The silica overlayer which is useful for increasing the anisotropy field change, somewhat affects the magnetic properties of the implanted layer.

  19. Mechanical Properties of Mineralized Collagen Fibrils As Influenced By Demineralization

    SciTech Connect

    Balooch, M.; Habelitz, S.; Kinney, J.H.; Marshall, S.J.; Marshall, G.W.

    2009-05-11

    Dentin and bone derive their mechanical properties from a complex arrangement of collagen type-I fibrils reinforced with nanocrystalline apatite mineral in extra- and intrafibrillar compartments. While mechanical properties have been determined for the bulk of the mineralized tissue, information on the mechanics of the individual fibril is limited. Here, atomic force microscopy was used on individual collagen fibrils to study structural and mechanical changes during acid etching. The characteristic 67 nm periodicity of gap zones was not observed on the mineralized fibril, but became apparent and increasingly pronounced with continuous demineralization. AFM-nanoindentation showed a decrease in modulus from 1.5 GPa to 50 MPa during acid etching of individual collagen fibrils and revealed that the modulus profile followed the axial periodicity. The nanomechanical data, Raman spectroscopy and SAXS support the hypothesis that intrafibrillar mineral etches at a substantially slower rate than the extrafibrillar mineral. These findings are relevant for understanding the biomechanics and design principles of calcified tissues derived from collagen matrices.

  20. Influence of grape pomace extract incorporation on chitosan films properties.

    PubMed

    Ferreira, Andreia S; Nunes, Cláudia; Castro, Alichandra; Ferreira, Paula; Coimbra, Manuel A

    2014-11-26

    Chitosan has been studied as a renewable polymer to form edible films allowing the incorporation of functional compounds. The aim of this work was to evaluate the effects in the chitosan films properties of the incorporation of grape pomace extracts: 0.15% of hot water extract (mainly polysaccharides), 0.15 and 0.3% of chloroform extract (wax), and 0.3 and 0.75% of n-hexane extract (oil). The evaluation of the surface morphology revealed that the films with the aqueous extract had the most homogeneous and smoother topography. The incorporation of higher proportion of wax and oil led to changes in mechanical properties of the films, namely lower resistance and stiffness. The chitosan-based films with 0.75% oil demonstrated a 75% decrease of solubility in water, due to their hydrophobicity, as confirmed by the contact angle and surface free energy measurements. The hydrophobic films showed higher antioxidant capacity in organic medium (ABTS and DPPH assays) whereas the most hydrophilic films showed an improvement in FRAP and reducing power assays. Therefore, all the chitosan-based films prepared by incorporation of these grape pomace extracts are promising for food shelf life extension.

  1. 3-D Digital Imaging of Breast Calcifications: Improvements in Image Quality, and Development of Automated Reconstruction Methods

    DTIC Science & Technology

    2000-02-01

    evaluation of computer algorithms for identifying, segmenting and correlating calcifications. We have been able to develop two separate computer ... algorithms , one for identification and segmentation of potential calcifications, the other to find calcification triplets that should be paired. Both

  2. Influence of river discharge and ocean currents on coastal optical properties

    NASA Astrophysics Data System (ADS)

    Cherukuru, Nagur; Brando, Vittorio E.; Schroeder, Thomas; Clementson, Lesley A.; Dekker, Arnold G.

    2014-08-01

    The variability in the optical properties of a coastal region influenced by river runoff and multiple ocean currents in a southern hemisphere setting has been studied. The study area, Tasmanian coastal waters, is influenced by subtropical currents such as the East Australian Current (EAC) and the Zeehan Current (ZC) mix with cooler sub-Antarctic water (SAW). Freshwater discharges from rivers around the island and their mixing with the ocean currents also influence Tasmanian coastal waters. This study was performed to understand the influence of hydrodynamic processes on coastal optical properties and underwater light propagation. Physical, biogeochemical and optical properties were measured in Tasmanian coastal water during the austral autumn of 2007. In this study we found that physical properties have a good correlation with optical properties indicating the role played by hydrodynamic processes in distribution of optically active substances, optical properties of the water mass and underwater light propagation. Analysis of in situ salinity and temperature confirmed the presence of relatively cooler ZC in the South-West region, a cooler mixture of the ZC and SAW in the South-East, warm and saline EAC waters along the East coast and relatively cooler and fresh Bass straight waters along the North coast. In Tasmanian coastal waters light absorption in the water column is controlled by Coloured Dissolved Organic Matter (CDOM) with regionally varying contributions from Non-Algal Particulate (NAP) matter and phytoplankton. Absorption due to CDOM and NAP show a conservative mixing behaviour indicating that these biogeochemical components were delivered by the river and diluted in the coastal water. Suspended particulate matter in Tasmanian coastal water are highly scattering in nature and the beam attenuation is mainly due to light scattering. Variability in probability of light backscattering was mainly due to varying availability of non-algal particulate matter in

  3. Influence of mechanical activation of steel powder on its properties

    NASA Astrophysics Data System (ADS)

    Vaulina, O. Yu; Darenskaia, E. A.; Myachin, Y. V.; Vasilyeva, I. E.; Kulkov, S. N.

    2017-02-01

    It has been studied properties of stainless steel based powders after mechanical activation using planetary ball milling technique. It have been shown that after one minute mechanical activation porosity of sintered steel is less than 5%, which is less than the porosity of the sintered steel powder without mechanical activation. The sample without activation has austenite state, which changes after activation toaustenite and ferrite mixtures. X-ray analysis confirmed that the mechanical activation leads to a change in the phase state of the samples: the samples without activation of the FCC structure (γ-Fe), after activation - FCC (γ-Fe) and BCC (α-Fe). The hardness increases at increasing activation time from 800 MPa for the sample without mechanical activation to 1250 MPa for the sample with the activation time of 10 minutes.

  4. Nanoscale defect architectures and their influence on material properties

    NASA Astrophysics Data System (ADS)

    Campbell, Branton

    2006-10-01

    Diffraction studies of long-range order often permit one to unambiguously determine the atomic structure of a crystalline material. Many interesting material properties, however, are dominated by nanoscale crystal defects that can't be characterized in this way. Fortunately, advances in x-ray detector technology, synchrotron x-ray source brightness, and computational power make it possible to apply new methods to old problems. Our research group uses multi-megapixel x-ray cameras to map out large contiguous volumes of reciprocal space, which can then be visually explored using graphics engines originally developed by the video-game industry. Here, I will highlight a few recent examples that include high-temperature superconductors, colossal magnetoresistors and piezoelectric materials.

  5. Influence of Oxidation on Electrical Properties of Compacted Cu Nanopowders

    NASA Astrophysics Data System (ADS)

    Nadutov, Volodymyr; Perekos, Anatoliy; Kokorin, Volodymyr; Konoplyuk, Sergiy; Kabantsev, Taras

    2016-10-01

    The phase composition and electrical transport properties of Cu powder obtained by electric spark dispersion and the pellets manufactured from this powder were studied by X-ray phase analysis and electric resistance measurements. The compacted powders were annealed in pure Ar atmosphere. It was shown that electrical resistance of the compacted Cu specimens essentially depends on the annealing temperature. In particular, the electrical resistance of the pellet after annealing at 873 K decreases on heating at low temperatures (semiconducting mechanism). As the temperature is increased, semiconducting behavior of resistivity is altered for metallic one. This change of conductivity type is ascribed to formation of metallic oxide and modification of its content during annealing.

  6. Influence of Oxidation on Electrical Properties of Compacted Cu Nanopowders.

    PubMed

    Nadutov, Volodymyr; Perekos, Anatoliy; Kokorin, Volodymyr; Konoplyuk, Sergiy; Kabantsev, Taras

    2016-12-01

    The phase composition and electrical transport properties of Cu powder obtained by electric spark dispersion and the pellets manufactured from this powder were studied by X-ray phase analysis and electric resistance measurements. The compacted powders were annealed in pure Ar atmosphere. It was shown that electrical resistance of the compacted Cu specimens essentially depends on the annealing temperature. In particular, the electrical resistance of the pellet after annealing at 873 K decreases on heating at low temperatures (semiconducting mechanism). As the temperature is increased, semiconducting behavior of resistivity is altered for metallic one. This change of conductivity type is ascribed to formation of metallic oxide and modification of its content during annealing.

  7. Predicting molybdenum toxicity to higher plants: influence of soil properties.

    PubMed

    McGrath, S P; Micó, C; Curdy, R; Zhao, F J

    2010-10-01

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED50) of Mo in different soils, explaining>65% of the variance in ED50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations.

  8. Influence of porosity on thermophysical properties of a composite

    NASA Astrophysics Data System (ADS)

    Grishaeva, N. Yu.; Ljukshin, B. A.; Strukov, Yu. S.; Bochkareva, S. A.

    2015-10-01

    In many modern information systems, the heat generated during the operation of electronic devices is usually dissipated by heat-conductive pads between the casing of the respective equipment and a massive base (platform). For newly developed pads, the promising materials are composites on the basis of various types of silicone rubber. At the same time, during the production of the pads without a vacuum setup, the material can contain air bubbles, which causes the porosity potentially negative for the thermal properties of the material. This work studies the thermal conductivity depending on the degree of silicone matrix filling by copper particles, introduced to improve thermal conductivity, and by air bubbles that are considered as reinforcing inclusions.

  9. Influence of porosity on thermophysical properties of a composite

    SciTech Connect

    Grishaeva, N. Yu. Ljukshin, B. A. Bochkareva, S. A.; Strukov, Yu. S.

    2015-10-27

    In many modern information systems, the heat generated during the operation of electronic devices is usually dissipated by heat-conductive pads between the casing of the respective equipment and a massive base (platform). For newly developed pads, the promising materials are composites on the basis of various types of silicone rubber. At the same time, during the production of the pads without a vacuum setup, the material can contain air bubbles, which causes the porosity potentially negative for the thermal properties of the material. This work studies the thermal conductivity depending on the degree of silicone matrix filling by copper particles, introduced to improve thermal conductivity, and by air bubbles that are considered as reinforcing inclusions.

  10. The influence of different modified graphene on property of DSSCs

    NASA Astrophysics Data System (ADS)

    Xu, Kai; Shen, Yue; Zhang, Zongkun; Cao, Meng; Gu, Feng; Wang, Linjun

    2016-01-01

    Two kinds of modified reduced graphene oxide (rGO) power with different hydrophilic property were synthesized in NH3/hydrazine hydrate (N-rGO) and KOH/hydrazine hydrate (K-rGO) reduction systems, respectively, and be used as counter electrode materials. The as-prepared rGO counter electrodes were confirmed as substitution for Pt counter electrode in dye-sensitized solar cells (DSSCs). The efficiency (η) of DSSCs based on N-rGO counter electrodes achieved 4.72% while that of K-rGO counter electrode was just 3.38%. The electrochemical impedance spectroscopy (EIS) measurements revealed that the hydrophilic K-rGO counter electrode has a low charge transfer resistance (Rct) and the hydrophobic N-rGO counter electrode has a low series resistance (Rs).

  11. Microfiller influence on structure and properties of the composite

    NASA Astrophysics Data System (ADS)

    Grishaeva, Natalia; Ljukshin, Boris; Panin, Sergey; Bochkareva, Svetlana

    2015-10-01

    It is demonstrated that the introduction of the particulate microfiller Al2O3 micron size (50 μm) to about 20% by weight affects the mechanical friction and improves the wear resistance properties of the ultra-high molecular weight polyethylene polyethylene (UHMWPE). Experimental studies of coatings based on the UHMWPE filled materials showed that the degree of crystallinity of such materials in increasing the proportion of filler is reduced as compared to the pure UHMWPE, wherein the modulus of elasticity and strength increases. Theoretical analysis of the deformation process of the filled UHMWPE is carried out using the finite element method in conjunction with the procedure consecutive cases. The comparative analysis is performed for the experimental data calculated in the flat setting to enter the correction factor.

  12. The calcification of fibrin in vitro

    NASA Astrophysics Data System (ADS)

    Koutsopoulos, S.; Dalas, E.

    2000-06-01

    In the present work we employed fibrin in order to assess its capability to induce biological mineralization. Fibrin is a very important factor in the blood-clotting system. Structurally, fibrin is an ordered organic matrix which has a periodic structure that repeats every 230 Å. Hydroxyapatite, HAP and octacalcium phosphate (OCP) are the most interesting calcium phosphate salts. Hydroxyapatite is thermodynamically the most stable calcium phosphate which is mostly used as a model compound for the study of biological-calcification processes. On the other hand, octacalcium phosphate has been proposed as a precursor of hydroxyapatite whose formation is favoured kinetically in solutions supersaturated to both salts. The kinetics of crystallization of HAP and OCP on fibrin were studied using the constant composition technique. The onset of HAP crystallization started immediately after introducing the substrate in the supersaturated solution. Unlike HAP crystallization induction periods were observed before the appearance of OCP precipitate in a solution supersaturated with respect to both HAP and OCP. Using nucleation rate equations derived from the classical homogeneous nucleation theory, interfacial energies and the size of the critical nucleus for both HAP and OCP were calculated. Phosphate was taken up extensively by the biological molecule studied. The dependence of adsorption upon ionic strength and pH of the medium suggests an appreciable contribution of electrostatic forces. Controversially calcium ions did not exhibit any detectable adsorption from solutions containing calcium dichloride at concentrations ranging from 1×10 -4 to 5×10 -3 M in 0.15 M NaCl supporting electrolyte, 37°C, pH=7.4. From the results above it follows that formation of HAP on fibrin may be initiated via adsorption of inorganic phosphate on the biological substrate.

  13. Epilepsy, occipital calcifications, and oligosymptomatic celiac disease in childhood.

    PubMed

    Arroyo, Hugo A; De Rosa, Susana; Ruggieri, Victor; de Dávila, María T G; Fejerman, Natalio

    2002-11-01

    The association of epilepsy, occipital calcifications, and celiac disease has been recognized as a distinct syndrome. The objective of this study was to present the clinical, electrophysiologic, and neuroradiologic features in a series of patients with this syndrome. Thirty-two patients with the constellation of epilepsy, occipital calcifications, and celiac disease were identified in our epilepsy clinic. The mean age was 11 years and the mean length of follow-up was 7.4 years. The 1990 criteria of the European Society of Pediatric Gastroenterology and Nutrition were used to diagnose celiac disease. The Kruskal-Wallis statistics test was employed with a signficance of P < .05. Thirty-one patients had partial seizures, 21 of them with symptoms related to the occipital lobe. In most patients, the epilepsy was controlled or the seizures were sporadic. Three developed severe epilepsy. Occipital calcifications were present in all cases. Computed tomography in 7 patients showed hypodense areas in the white matter around calcifications, which decreased or disappeared after a period of gluten-free diet in 3 patients. A favorable outcome of epilepsy was detected in patients with the earliest dietary therapy. This study presents the largest series of children with this syndrome outside Italy. White-matter hypodensities surrounding calcifications are rarely reported. A prompt diagnosis of celiac disease might improve the evolution of the epilepsy and may improve cognitive status.

  14. Chemical modifications of graphene and their influence on properties of polyurethane composites: a review

    NASA Astrophysics Data System (ADS)

    Włodarczyk, D.; Urban, M.; Strankowski, M.

    2016-10-01

    Polyurethane composites are materials of great interest nowadays due to their wide range of available forms and applications in industry. Controlling and achieving unique properties via matrix modifications and addition of various specific nanofillers seems be one of the key elements to success. The purpose of this work is to briefly present some examples of graphene nanoderivatives, their syntheses, properties and influence on polyurethane matrix after application. Structural, mechanical and electrical properties of graphene nanofillers were analyzed before and after implementation into polymer matrices. Additionally properties of obtained composites were considered in the context of shape memory. The first chapter presents methods of synthesizing carbon nanofillers and some structure investigations via x-ray Diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy. The second part discusses influence of graphene modifications on polymer structure and changes in thermomechanical properties via stress-strain tests and Thermogravimetry (TG).

  15. Influence of the processed sunflower oil on the cement properties

    NASA Astrophysics Data System (ADS)

    Fleysher, A. U.; Tokarchuk, V. V.; Sviderskiy, V. A.

    2015-01-01

    Used oils (vegetable oil, animal oil, engine oil, etc.), which are essentially industrial wastes, have found application as secondary raw materials in some braches of industry. In particular, the only well-known and commonly-used way of utilizing wastes of vegetable oils is to apply them as raw materials in the production of biodiesel. The goal of the present study is to develop a conceptually new way of vegetable oil wastes utilization in the building industry. The test admixture D-148 was obtained from the processing of wastes of sunflower oil and it mainly consists of fatty acid diethanolamide. The test admixture was added to the cement system for the purpose of studying its influence on water demand, flowability, setting times, compressive strength and moisture adsorption. The test admixture D-148 at the optimal content 0. 2 weight % causes 10% decrease in water demand, 1.7 time increase in flowability (namely spread diameter), 23% increase in grade strength and 34% decrease in moisture adsorption. The results of the present investigation make it possible to consider the final product of the waste sunflower oil processing as multifunctional plasticizing-waterproofing admixture.

  16. Viscoelastic properties of actin networks influence material transport

    NASA Astrophysics Data System (ADS)

    Stam, Samantha; Weirich, Kimberly; Gardel, Margaret

    2015-03-01

    Directed flows of cytoplasmic material are important in a variety of biological processes including assembly of a mitotic spindle, retraction of the cell rear during migration, and asymmetric cell division. Networks of cytoskeletal polymers and molecular motors are known to be involved in these events, but how the network mechanical properties are tuned to perform such functions is not understood. Here, we construct networks of either semiflexible actin filaments or rigid bundles with varying connectivity. We find that solutions of rigid rods, where unimpeded sliding of filaments may enhance transport in comparison to unmoving tracks, are the fastest at transporting network components. Entangled solutions of semiflexible actin filaments also transport material, but the entanglements provide resistance. Increasing the elasticity of the actin networks with crosslinking proteins slows network deformation further. However, the length scale of correlated transport in these networks is increased. Our results reveal how the rigidity and connectivity of biopolymers allows material transport to occur over time and length scales required for physiological processes. This work was supported by the U. Chicago MRSEC

  17. Influences of aquifer properties on flow dimensions in dolomites.

    PubMed

    Verbovsek, Timotej

    2009-01-01

    The paper focuses on analyses and correlations of flow dimensions in different dolomite aquifers in Slovenia. Flow dimensions are obtained through the reinterpretation of 72 pumping tests with the generalized radial flow model, based on the fractional flow dimension. The average value of flow dimensions is 2.16 for all dolomites. A study of flow dimensions in individual aquifers categorized according to their lithological properties shows that higher dimensions occur in massive late-diagenetic Cordevolian and Anisian dolomites compared with bedded Main, Baca, and especially Lower Triassic dolomites, which contain a greater proportion of noncarbonate minerals. Partially penetrating wells have higher flow dimensions than fully penetrating wells. Flow dimensions are poorly correlated with hydraulic conductivities of fractures. When comparing the quantities of major dissolved minerals, obtained by hydrogeochemical inverse modeling, with the values of flow dimensions, the Cordevolian and Anisian dolomites are found to exhibit the highest values of both dissolved dolomite and flow dimensions, indicating that greater dissolution occurs at higher flow dimensions. For other aquifers, data points are more scattered and the correlation is mostly poor. When compared with three-dimensional fractal dimensions of fracture networks, there is no correlation with flow dimensions. However, almost all the values of flow dimensions are lower than the corresponding fractal dimensions in dolomites (average D= 2.77), possibly indicating the channeling of flow within the available space of the fracture networks, consequently reducing the flow dimensions.

  18. Influence of moisture content on physical properties of minor millets.

    PubMed

    Balasubramanian, S; Viswanathan, R

    2010-06-01

    Physical properties including 1000 kernel weight, bulk density, true density, porosity, angle of repose, coefficient of static friction, coefficient of internal friction and grain hardness were determined for foxtail millet, little millet, kodo millet, common millet, barnyard millet and finger millet in the moisture content range of 11.1 to 25% db. Thousand kernel weight increased from 2.3 to 6.1 g and angle of repose increased from 25.0 to 38.2°. Bulk density decreased from 868.1 to 477.1 kg/m(3) and true density from 1988.7 to 884.4 kg/m(3) for all minor millets when observed in the moisture range of 11.1 to 25%. Porosity decreased from 63.7 to 32.5%. Coefficient of static friction of minor millets against mild steel surface increased from 0.253 to 0.728 and coefficient of internal friction was in the range of 1.217 and 1.964 in the moisture range studied. Grain hardness decreased from 30.7 to 12.4 for all minor millets when moisture content was increased from 11.1 to 25% db.

  19. Decreased calcification in the Southern Ocean over the satellite record

    NASA Astrophysics Data System (ADS)

    Freeman, Natalie M.; Lovenduski, Nicole S.

    2015-03-01

    Widespread ocean acidification is occurring as the ocean absorbs anthropogenic carbon dioxide from the atmosphere, threatening marine ecosystems, particularly the calcifying plankton that provide the base of the marine food chain and play a key role within the global carbon cycle. We use satellite estimates of particulate inorganic carbon (PIC), surface chlorophyll, and sea surface temperature to provide a first estimate of changing calcification rates throughout the Southern Ocean. From 1998 to 2014 we observe a 4% basin-wide reduction in summer calcification, with ˜9% reductions in large regions (˜1 × 106 km2) of the Pacific and Indian sectors. Southern Ocean trends are spatially heterogeneous and primarily driven by changes in PIC concentration (suspended calcite), which has declined by ˜24% in these regions. The observed decline in Southern Ocean calcification and PIC is suggestive of large-scale changes in the carbon cycle and provides insight into organism vulnerability in a changing environment.

  20. Declining Coral Calcification on the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    De'ath, Glenn; Lough, Janice M.; Fabricius, Katharina E.

    2009-01-01

    Reef-building corals are under increasing physiological stress from a changing climate and ocean absorption of increasing atmospheric carbon dioxide. We investigated 328 colonies of massive Porites corals from 69 reefs of the Great Barrier Reef (GBR) in Australia. Their skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined by 13.3%. The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years. Calcification increases linearly with increasing large-scale sea surface temperature but responds nonlinearly to annual temperature anomalies. The causes of the decline remain unknown; however, this study suggests that increasing temperature stress and a declining saturation state of seawater aragonite may be diminishing the ability of GBR corals to deposit calcium carbonate.

  1. Pediatric intervertebral disc calcification: A no touch lesion.

    PubMed

    Garg, Monika; Kumar, Sanyal; Satija, Bhawna; Gupta, Rajat

    2012-01-01

    Intervertebral disc calcification (IVDC), though rare, remains an important differential of pediatric spinal pain. A 7-year-old boy presented with sudden-onset severe neck pain and restricted movements. There was no definite history of trauma or infection. Imaging of the cervical spine showed calcification of the intervertebral disc at C2-3 level, with significant posterior protrusion into the spinal canal causing compression of the cervical spinal cord. The child was kept on conservative management. The calcification and posterior protrusion showed near-complete resolution on 3-month follow-up. This case report emphasizes that childhood IVDC is a benign condition which commonly resolves spontaneously, without any surgical intervention and neurological sequelae.

  2. The influence of nanopore dimensions on the electrochemical properties of nanopore arrays studied by impedance spectroscopy.

    PubMed

    Kant, Krishna; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-11-11

    The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores.

  3. Early detection of ocean acidification effects on marine calcification

    SciTech Connect

    Ilyina, T.; Zeebe, R. E.; E. Maier-Reimer; C. Heinze

    2009-02-19

    Ocean acidification is likely to impact calcification rates in many pelagic organisms, which may in turn cause significant changes in marine ecosystem structure. We examine effects of changes in marine CaCO3 production on total alkalinity (TA) in the ocean using the global biogeochemical ocean model HAMOCC. We test a variety of future calcification scenarios because experimental studies with different organisms have revealed a wide range of calcification sensitivities to CaCO3 saturation state. The model integrations start at a preindustrial steady state in the year 1800 and run until the year 2300 forced with anthropogenic CO2 emissions. Calculated trends in TA are evaluated taking into account the natural variability in ocean carbonate chemistry, as derived from repeat hydrographic transects. We conclude that the data currently available does not allow discerning significant trends in TA due to changes in pelagic calcification caused by ocean acidification. Given different calcification scenarios, our model calculations indicate that the TA increase over time will start being detectable by the year 2040, increasing by 5–30 umol/kg compared to the present-day values. In a scenario of extreme reductions in calcification, large TA changes relative to preindustrial conditions would have occurred at present, which we consider very unlikely. However, the time interval of reliable TA observations is too short to disregard this scenario. The largest increase in surface ocean TA is predicted for the tropical and subtropical regions. In order to monitor and quantify possible early signs of acidification effects, we suggest to specifically target those regions during future ocean chemistry surveys.

  4. Alkalinity Enrichment Enhances Net Calcification of a Coral Reef Flat

    NASA Astrophysics Data System (ADS)

    Albright, R.; Caldeira, K.

    2015-12-01

    Ocean acidification is projected to shift reefs from a state of net accretion to one of net dissolution sometime this century. While retrospective studies show large-scale changes in coral calcification over the last several decades, it is not possible to unequivocally link these results to ocean acidification due to confounding factors of temperature and other environmental parameters. Here, we quantified the calcification response of a coral reef flat to alkalinity enrichment to test whether reef calcification increases when ocean chemistry is restored to near pre-industrial conditions. We used sodium hydroxide (NaOH) to increase the total alkalinity of seawater flowing over a reef flat, with the aim of increasing carbonate ion concentrations [CO32-] and the aragonite saturation state (Ωarag) to values that would have been attained under pre-industrial atmospheric pCO2 levels. We developed a dual tracer regression method to estimate alkalinity uptake (i.e., calcification) in response to alkalinity enrichment. This approach uses the change in ratios between a non-conservative tracer (alkalinity) and a conservative tracer (a non-reactive dye, Rhodamine WT) to assess the fraction of added alkalinity that is taken up by the reef as a result of an induced increase in calcification rate. Using this method, we estimate that an average of 17.3% ± 2.3% of the added alkalinity was taken up by the reef community. In providing results from the first seawater chemistry manipulation experiment performed on a natural coral reef community (without artificial confinement), we demonstrate that, upon increase of [CO32-] and Ωarag to near pre-industrial values, reef calcification increases. Thus, we conclude that, the impacts of ocean acidification are already being felt by coral reefs. This work is the culmination of years of work in the Caldeira lab at the Carnegie Institution for Science, involving many people including Jack Silverman, Kenny Schneider, and Jana Maclaren.

  5. [Mechanism of losartan suppressing vascular calcification in rat aortic artery].

    PubMed

    Shao, Juan; Wu, Panfeng; Wu, Jiliang; Li, Mincai

    2016-08-01

    Objective To investigate the effect of the angiotensin II receptor 1 (AT1R) blocker losartan on vascular calcification in rat aortic artery and explore the underlying mechanisms. Methods SD rats were divided randomly into control group, vascular calcification model group and treatment group. Vascular calcification models were made by subcutaneous injection of warfarin plus vitamin K1 for two weeks. Rats in the treatment group were subcutaneously injected with losartan (10 mg/kg) at the end of the first week and consecutively for one week. We observed the morphological changes by HE staining and the calcium deposition by Alizarin red staining in the artery vascular wall. The mRNA expressions of bone morphogenetic protein 2 (BMP2) and Runt-related transcription factor 2 (RUNX2) were analyzed by reverse transcription PCR. The BMP2 and RUNX2 protein expressions were determined by Western blotting. The apoptosis of smooth muscle cells (SMCs) were detected by TUNEL. The AT1R expression was tested by fluorescent immunohistochemistry. Results The aortic vascular calcification was induced by warfarin and vitamin K1. Compared with the vascular calcification model group, the mRNA and protein expressions of BMP2 and RUNX2 were significantly downregulated in the aorta in the losartan treatment group. Furthermore, the apoptosis of SMCs and the AT1R expression obviously decreased. Conclusion AT1R blocker losartan inhibits the apoptosis of SMCs and reduces AT1R expression; it downregulates the BMP2 and RUNX2 expressions in the vascular calcification process.

  6. Reversal of ocean acidification enhances net coral reef calcification.

    PubMed

    Albright, Rebecca; Caldeira, Lilian; Hosfelt, Jessica; Kwiatkowski, Lester; Maclaren, Jana K; Mason, Benjamin M; Nebuchina, Yana; Ninokawa, Aaron; Pongratz, Julia; Ricke, Katharine L; Rivlin, Tanya; Schneider, Kenneth; Sesboüé, Marine; Shamberger, Kathryn; Silverman, Jacob; Wolfe, Kennedy; Zhu, Kai; Caldeira, Ken

    2016-03-17

    Approximately one-quarter of the anthropogenic carbon dioxide released into the atmosphere each year is absorbed by the global oceans, causing measurable declines in surface ocean pH, carbonate ion concentration ([CO3(2-)]), and saturation state of carbonate minerals (Ω). This process, referred to as ocean acidification, represents a major threat to marine ecosystems, in particular marine calcifiers such as oysters, crabs, and corals. Laboratory and field studies have shown that calcification rates of many organisms decrease with declining pH, [CO3(2-)], and Ω. Coral reefs are widely regarded as one of the most vulnerable marine ecosystems to ocean acidification, in part because the very architecture of the ecosystem is reliant on carbonate-secreting organisms. Acidification-induced reductions in calcification are projected to shift coral reefs from a state of net accretion to one of net dissolution this century. While retrospective studies show large-scale declines in coral, and community, calcification over recent decades, determining the contribution of ocean acidification to these changes is difficult, if not impossible, owing to the confounding effects of other environmental factors such as temperature. Here we quantify the net calcification response of a coral reef flat to alkalinity enrichment, and show that, when ocean chemistry is restored closer to pre-industrial conditions, net community calcification increases. In providing results from the first seawater chemistry manipulation experiment of a natural coral reef community, we provide evidence that net community calcification is depressed compared with values expected for pre-industrial conditions, indicating that ocean acidification may already be impairing coral reef growth.

  7. Reversal of ocean acidification enhances net coral reef calcification

    NASA Astrophysics Data System (ADS)

    Albright, Rebecca; Caldeira, Lilian; Hosfelt, Jessica; Kwiatkowski, Lester; MacLaren, Jana K.; Mason, Benjamin M.; Nebuchina, Yana; Ninokawa, Aaron; Pongratz, Julia; Ricke, Katharine L.; Rivlin, Tanya; Schneider, Kenneth; Sesboüé, Marine; Shamberger, Kathryn; Silverman, Jacob; Wolfe, Kennedy; Zhu, Kai; Caldeira, Ken

    2016-03-01

    Approximately one-quarter of the anthropogenic carbon dioxide released into the atmosphere each year is absorbed by the global oceans, causing measurable declines in surface ocean pH, carbonate ion concentration ([CO32-]), and saturation state of carbonate minerals (Ω). This process, referred to as ocean acidification, represents a major threat to marine ecosystems, in particular marine calcifiers such as oysters, crabs, and corals. Laboratory and field studies have shown that calcification rates of many organisms decrease with declining pH, [CO32-], and Ω. Coral reefs are widely regarded as one of the most vulnerable marine ecosystems to ocean acidification, in part because the very architecture of the ecosystem is reliant on carbonate-secreting organisms. Acidification-induced reductions in calcification are projected to shift coral reefs from a state of net accretion to one of net dissolution this century. While retrospective studies show large-scale declines in coral, and community, calcification over recent decades, determining the contribution of ocean acidification to these changes is difficult, if not impossible, owing to the confounding effects of other environmental factors such as temperature. Here we quantify the net calcification response of a coral reef flat to alkalinity enrichment, and show that, when ocean chemistry is restored closer to pre-industrial conditions, net community calcification increases. In providing results from the first seawater chemistry manipulation experiment of a natural coral reef community, we provide evidence that net community calcification is depressed compared with values expected for pre-industrial conditions, indicating that ocean acidification may already be impairing coral reef growth.

  8. The meniscus, calcification and osteoarthritis: a pathologic team.

    PubMed

    MacMullan, Paul A; McCarthy, Geraldine M

    2010-01-01

    Articular calcification correlates with osteoarthritis (OA) severity but its exact role in the disease process is unclear. In examining OA meniscal cell function, Sun and colleagues have shown recently that meniscal cells from end-stage OA subjects can generate calcium crystals and that genes involved in calcification are upregulated in OA meniscal cells. Also, this in vitro calcium deposition by OA menisci is inhibited by phosphocitrate. This study should catalyse further work examining the pathological contribution or otherwise of calcium crystals in OA. This would significantly aid the development of potential disease modifying agents in OA, which are currently unavailable.

  9. Evaluation and nonsurgical management of rotator cuff calcific tendinopathy.

    PubMed

    Greis, Ari C; Derrington, Stephen M; McAuliffe, Matthew

    2015-04-01

    Rotator cuff calcific tendinopathy is a common finding that accounts for about 7% of patients with shoulder pain. There are numerous theories on the pathogenesis of rotator cuff calcific tendinopathy. The diagnosis is confirmed with radiography, MRI or ultrasound. There are numerous conservative treatment options available and most patients can be managed successfully without surgical intervention. Nonsteroidal anti-inflammatory drugs and multiple modalities are often used to manage pain and inflammation; physical therapy can help improve scapular mechanics and decrease dynamic impingement; ultrasound-guided needle aspiration and lavage techniques can provide long-term improvement in pain and function in these patients.

  10. Genetic Associations with Valvular Calcification and Aortic Stenosis

    PubMed Central

    Thanassoulis, George; Campbell, Catherine Y.; Owens, David S.; Smith, J. Gustav; Smith, Albert V.; Peloso, Gina M.; Kerr, Kathleen F.; Pechlivanis, Sonali; Budoff, Matthew J.; Harris, Tamara B.; Malhotra, Rajeev; O’Brien, Kevin D.; Kamstrup, Pia R.; Nordestgaard, Børge G.; Tybjaerg-Hansen, Anne; Allison, Matthew A.; Aspelund, Thor; Criqui, Michael H.; Heckbert, Susan R.; Hwang, Shih-Jen; Liu, Yongmei; Sjogren, Marketa; van der Pals, Jesper; Kälsch, Hagen; Mühleisen, Thomas W.; Nöthen, Markus M.; Cupples, L. Adrienne; Caslake, Muriel; Di Angelantonio, Emanuele; Danesh, John; Rotter, Jerome I.; Sigurdsson, Sigurdur; Wong, Quenna; Erbel, Raimund; Kathiresan, Sekar; Melander, Olle; Gudnason, Vilmundur; O’Donnell, Christopher J.; Post, Wendy S.

    2013-01-01

    BACKGROUND Limited information is available regarding genetic contributions to valvular calcification, which is an important precursor of clinical valve disease. METHODS We determined genomewide associations with the presence of aorticvalve calcification (among 6942 participants) and mitral annular calcification (among 3795 participants), as detected by computed tomographic (CT) scanning; the study population for this analysis included persons of white European ancestry from three cohorts participating in the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium (discovery population). Findings were replicated in independent cohorts of persons with either CT-detected valvular calcification or clinical aortic stenosis. RESULTS One SNP in the lipoprotein(a) (LPA) locus (rs10455872) reached genomewide significance for the presence of aorticvalve calcification (odds ratio per allele, 2.05; P = 9.0×10−10), a finding that was replicated in additional white European, African-American, and Hispanic-American cohorts (P<0.05 for all comparisons). Genetically determined Lp(a) levels, as predicted by LPA genotype, were also associated with aorticvalve calcification, supporting a causal role for Lp(a). In prospective analyses, LPA genotype was associated with incident aortic stenosis (hazard ratio per allele, 1.68; 95% confidence interval [CI], 1.32 to 2.15) and aortic-valve replacement (hazard ratio, 1.54; 95% CI, 1.05 to 2.27) in a large Swedish cohort; the association with incident aortic stenosis was also replicated in an independent Danish cohort. Two SNPs (rs17659543 and rs13415097) near the proinflammatory gene IL1F9 achieved genomewide significance for mitral annular calcification (P = 1.5×10−8 and P = 1.8×10−8, respectively), but the findings were not replicated consistently. CONCLUSIONS Genetic variation in the LPA locus, mediated by Lp(a) levels, is associated with aorticvalve calcification across multiple ethnic groups and with incident

  11. Influence of emulsifying agents on the properties of cellulose acetate butyrate and ethylcellulose microcapsules.

    PubMed

    Kristmundsdóttir, T; Ingvarsdóttir, K

    1994-01-01

    Microcapsules of ibuprofen were prepared according to the solvent evaporation method, using two coating polymers, cellulose acetate butyrate and ethylcellulose. The influence of two emulsifying agents, polysorbat 80 and polyvinyl alcohol, on the properties of the microcapsules was investigated. The results show that type and concentration of emulsifying agent influences size distribution, drug loading and amount of free drug on the surface of the microcapsules.

  12. Influence of surface reconstruction on dopant incorporation and transport properties of GaAs(Bi) alloys

    NASA Astrophysics Data System (ADS)

    Field, R. L.; Occena, J.; Jen, T.; Del Gaudio, D.; Yarlagadda, B.; Kurdak, C.; Goldman, R. S.

    2016-12-01

    We report on the influence of surface reconstruction on silicon dopant incorporation and transport properties during molecular-beam epitaxy of GaAs(Bi) alloys. GaAs(Bi) growth with an (n × 3) reconstruction leads to n-type conductivity, while growth with a (2 × 1) reconstruction leads to p-type conductivity. We hypothesize that the presence or absence of surface arsenic dimers prevents or enables dopant incorporation into arsenic lattice sites. We consider the influence of bismuth anions on arsenic-dimer mediated dopant incorporation and the resulting electronic transport properties, demonstrating the applicability of this mechanism to mixed anion semiconductor alloys.

  13. Influence of excess diamine on properties of PMR polyimide resins and composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, F. I.

    1980-01-01

    By varying the stoichiometry of the reactants in the preparation of PMR polyimide resin, changes occur in molecular weight distribution which influence the rheological properties and thus the processability of the resin, as well as the mechanical properties of the composite. The influence of 1-10 percent molar excess MDA on the molecular weight distribution and rheological properties of an imidized PMR system were exposed. Molecular weight distribution is characterized by gel permeation chromatography of the imidized molding compound; shear viscosity is related to changes in average molecular weight. The thermo-oxidative stability at 600 F, glass transition temperature, flexural and interlaminar shear properties of PMR polyimide/Celion 6000 graphite fiber composites are compared as a function of the percent excess MDA in the monomer reactant mixture.

  14. Influence of the structural properties on the pseudocritical magnetic behavior of single-wall ferromagnetic nanotubes

    NASA Astrophysics Data System (ADS)

    Salazar-Enríquez, C. D.; Restrepo-Parra, E.; Restrepo, J.

    2012-04-01

    In this work we address the influence of the crystalline structure, concretely when the system under study is formed by square or hexagonal unit cells, upon the magnetic properties and pseudocritical behavior of single-wall ferromagnetic nanotubes. We focus not only on the effect of the geometrical shape of the unit cell but also on their dimensions. The model employed is based on the Monte Carlo method, the Metropolis dynamics and a nearest neighbors classical Heisenberg Hamiltonian. Magnetization per magnetic site, magnetic susceptibility, specific heat and magnetic energy were computed. These properties were computed varying the system size, unit cell dimension and temperature. The dependence of the nearest neighbor exchange integral on the nanotubes geometrical characteristics is also discussed. Results revealed a strong influence of the system topology on the magnetic properties caused by the difference in the coordination number between square and hexagonal unit cell. Moreover, the nanotubes diameter influence on magnetic properties is only observed at very low values, when the distance between atoms is less than it, presented by the 2D sheet. On the other hand, it was concluded that the surface-related finite-size effects do not influence the magnetic nanotubes properties, contrary to the case of other nano-systems as thin films and nanoparticles among others.

  15. Dephosphorylation of circulating human Osteopontin correlates with severe valvular calcification in patients with Calcific Aortic Valve Disease

    PubMed Central

    Sainger, Rachana; Grau, Juan B.; Poggio, Paolo; Branchetti, Emanuela; Bavaria, Joseph E.; Gorman, Joseph H.; Gorman, Robert C.; Ferrari, Giovanni

    2011-01-01

    Context Calcific Aortic Valve Disease (CAVD) is an active pathological process leading to biomineralization of the aortic cusps. We characterized circulating and tissue Osteopontin (OPN) as a biomarker for CAVD. Objectives Here we investigate the post-translational modifications of circulating OPN and correlate the phosphorylation status with the ability to prevent calcification. Methods Circulating OPN levels were estimated in CAVD patients (n=51) and controls (n=56). In a subgroup of 27 subjects, OPN was purified and the phosphorylation status analyzed. Results Plasma OPN levels were significantly elevated in CAVD patients as compared to the controls and correlates with the aortic valve calcium score. Our study demonstrates that phospho-threonine levels of OPN purified from controls were higher when compared to CAVD subjects, while phosphoserine and phospho-tyrosine levels were comparable between the two groups. Conclusion The dephosphorylation of circulating OPN correlates with severe valvular calcification in patients with CAVD. PMID:22191734

  16. Absorption measurement of thin films by using photothermal techniques: The influence of thermal properties

    SciTech Connect

    Wu, Z.L.; Kuo, P.K.; Thomas, R.L.; Fan, Z.X.

    1995-12-31

    Photothermal techniques are widely used for measuring optical absorption of thin film coatings. In these applications the calibration of photothermal signal is typically based on the assumption that the thermal properties of the thin film make very little contribution. In this paper we take mirage technique as an example and present a detailed analysis of the influence of thin film thermal properties on absorption measurements. The results show that the traditional calibration method is not valid on surprisingly many situations.

  17. Influence of nonmartensitic transformation products on mechanical properties of tempered martensite

    NASA Technical Reports Server (NTRS)

    Hodge, J M; Lankford, W T

    1952-01-01

    The influence of nonmartensitic transformations products on the mechanical properties of tempered martensite is presented for samples of a SAE 4340 steel, partially isothermally transformed to specific high-temperature transformation products and quenched and tempered to hardness values of from 25 to 40 Rockwell c. The effects of upper bainite in amounts of 1,5, 10, 20 and 50 percent, of 5 percent ferrite, and of 5 percent pearlite on the tensile, impact, and fatigue properties are evaluated. (author)

  18. Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO₂.

    PubMed

    Sett, Scarlett; Bach, Lennart T; Schulz, Kai G; Koch-Klavsen, Signe; Lebrato, Mario; Riebesell, Ulf

    2014-01-01

    Increasing atmospheric CO₂ concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO₂ gradient ranging from ∼0.5-250 µmol kg⁻¹ (i.e. ∼20-6000 µatm pCO₂) at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica). Both species showed CO₂-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO₂. CO₂ optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO₂ concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO₂ concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean.

  19. The kinetics of Dissolution of Biologically Formed Calcific Deposits.

    NASA Astrophysics Data System (ADS)

    Rokidi, Stamatia; Koutsoukos, Petros

    2015-04-01

    The calcification of aortic valves results in the formation of non stoichiometric apatitic deposits which may have serious health implications because of the fact that these minerals adhere tenaciously on tissues like heart valves and arteries causing permanent damage which is partly due to their low solubility. In the present work, calcium phosphate biominerals were extracted from clinically removed tissues and were characterized with respect to their mineralogical constituents and other properties including morphology, specific surface area analyses and thermogravimetric analysis. In all cases, the biominerals may be described as non stoichiometric apatitic materials, although traces of the precursor phase of octacalcium phosphate (Ca8H2(PO4)6•5H2O, OCP) were identified on the basis of their morphological examination. The kinetics of dissolution of the biomineral deposits was investigated in solutions undersaturated with respect to hydroxyapatite (Ca5(PO4)3OH, HAP) at conditions of constant undersaturation at pH 7.40, 37°C, 0.15M NaCl. Synthetic stoichiometric HAP was used as the control mineral. The experiments in the present work used solutions prepared from calcium chloride and sodium hydrogen phosphate and the relative undersaturation, σ, was in the range 0.38-0.74 with respect to HAP and 0.49-0.85 with respect to OCP (σ=1 in water). The dissolution process started immediately upon the introduction of an accurately weighted amount of powdered biomineral in the undersaturated solutions homogenized by magnetic stirring. Inert atmosphere was ensured with the bubbling of water vapor saturated nitrogen through the demineralizing solutions. A glass/Ag/AgCl combination electrode was used as a probe to monitor the process and to control the addition of diluent solutions with the stoichiometry of the dissolving mineral. The measurements of the rates of crystal dissolution, showed a parabolic dependence on the relative solution undersaturation for HAP and higher

  20. Intracranial physiological calcifications in adults on computed tomography in Tabriz, Iran.

    PubMed

    Daghighi, M H; Rezaei, V; Zarrintan, S; Pourfathi, H

    2007-05-01

    Intracranial physiological calcifications are unaccompanied by any evidence of disease and have no demonstrable pathological cause. They are often due to calcium and sometimes iron deposition in the blood vessels of different structures of the brain. Computed tomography (CT) is the most sensitive means of detection of these calcifications. The aim of this study was the assessment of intracranial physiological calcifications in adults. We studied 1569 cases ranging in age from 15 to 85 in Tabriz Imam Khomeini Hospital, Iran. These patients had a history of head trauma and their CT scan did not show any evidence of pathological findings. The structures evaluated consisted of (A) the pineal gland, (B) the choroid plexus, (C) the habenula, (D) the basal ganglia, (E) the tentorium cerebelli, sagittal sinus and falx cerebri, (F) vessels and (G) lens and other structures which could be calcified. Of the 1569 subjects, 71.0% had pineal calcification, 66.2% had choroid plexus calcification, 20.1% had habenular calcification, 7.3% had tentorium cerebelli, sagittal sinus or falx cerebri calcifications, 6.6% had vascular calcification, 0.8% had basal ganglia calcification and 0.9% had lens and other non-defined calcifications. In general, the frequency of intracranial physiological calcifications was greater in men than in women. All types of calcification increased at older ages except for lens and other non-defined calcifications. We evaluated all the cranial structures and determined percentages for all types of intracranial physiological calcification. These statistics can be used for comparing physiological and pathological intracranial calcifications. Moreover, these statistics may be of interest from the clinical perspective and are potentially of clinical use.

  1. A red herring in vascular calcification: ‘nanobacteria’ are protein–mineral complexes involved in biomineralization

    PubMed Central

    Krüger, Thilo; Heiss, Alexander; Jahnen-Dechent, Willi

    2011-01-01

    Biomineralization at pathological extraosseous sites (i.e. vasculature and soft tissues) is associated with increased morbidity and mortality. So-called ‘nanobacteria’ have been described as pathogenic agents causing many diseases including calcification. Initially, their appearance, and having a content consisting of nucleic acids plus proteins and properties of growing structures, suggested that they were living organisms. However, it could be demonstrated that the so-called nanobacteria were in fact mineralizing nanoparticles that contain mineral and non-mineral compounds, that these particles bind to charged molecules and that supersaturation enables in vitro growth of these nanoparticles. Recent data indicate that nanoparticles consisting of protein–mineral complexes can be seen both in vitro and in vivo as precursors of matrix calcification. PMID:21965584

  2. [Vascular calcifications, the hidden side effects of vitamin K antagonists].

    PubMed

    Bennis, Youssef; Vengadessane, Subashini; Bodeau, Sandra; Gras, Valérie; Bricca, Giampiero; Kamel, Saïd; Liabeuf, Sophie

    2016-09-01

    Despite the availability of new oral anticoagulants, vitamin K antagonists (VKA, such as fluindione, acenocoumarol or warfarin) remain currently the goal standard medicines for oral prevention or treatment of thromboembolic disorders. They inhibit the cycle of the vitamin K and its participation in the enzymatic gamma-carboxylation of many proteins. The VKA prevent the activation of the vitamin K-dependent blood clotting factors limiting thus the initiation of the coagulation cascade. But other proteins are vitamin K-dependent and also remain inactive in the presence of VKA. This is the case of matrix Gla-protein (MGP), a protein that plays a major inhibitory role in the development of vascular calcifications. Several experimental and epidemiological results suggest that the use of the VKA could promote the development of vascular calcifications increasing thus the cardiovascular risk. This risk seems to be higher in patients with chronic kidney disease or mellitus diabetes who are more likely to develop vascular calcifications, and may be due to a decrease of the MGP activity. This review aims at summarizing the data currently available making vascular calcifications the probably underestimated side effects of VKA.

  3. Histology of epiphyseal cartilage calcification and endochondral ossification.

    PubMed

    Amizuka, Norio; Hasegawa, Tomoka; Oda, Kimimitsu; Luiz de Freitas, Paulo Henrique; Hoshi, Kazuto; Li, Minqi; Ozawa, Hidehiro

    2012-01-01

    Cartilage calcification is carried out by chondrocytes as they hypertrophy and begin to secrete matrix vesicles. Calcification initiates when calcium phosphates appear inside these matrix vesicles, forming hydroxyapatite crystals that eventually break through the membrane to form calcifying globules, as in bone calcification. However, the extracellular environment in cartilage is different from that in bone: cartilage is abundant in proteoglycans but contains a small amount of osteopontin. Hypertrophic chondrocytes secrete vesicles in the cartilaginous matrix of intercolumnar septae only, forming well-calcified longitudinal septae and poorly-calcified transverse partitions. Such pattern of vesicle deposition permits the invasion of endothelial cells, which infiltrate into cartilage and induce migration of osteogenic and osteoclastic cells. Osteoclasts resorb the excess of calcified globules in the partitions, shaping calcified cartilage cores paralleling the longitudinal axis of long bones. After the formation of these calcified cartilage cores, endochondral ossification involves a series of well-defined events in which osteogenic cells deposit new bone onto the cartilage core and form primary trabecules. This review presents the histology of epiphyseal cartilage calcification and endochondral ossification.

  4. Metastatic calcification of the stomach imaged on a bone scan

    SciTech Connect

    Goldstein, R.; Ryo, U.Y.; Pinsky, S.M.

    1984-10-01

    A whole body bone scan obtained on a 21-year-old woman with sickle cell disease and chronic renal failure showed localization of the radionuclide diffusely in the stomach. The localization of the radionuclide represented metastatic calcification of the stomach caused by secondary hyperparathyroidism.

  5. Epilepsy in coeliac disease: not just a matter of calcifications.

    PubMed

    Licchetta, Laura; Bisulli, Francesca; Di Vito, Lidia; La Morgia, Chiara; Naldi, Ilaria; Volta, Umberto; Tinuper, Paolo

    2011-12-01

    The clinical spectrum of epilepsy related to celiac disease (CD) ranges from benign syndromes to intractable epilepsy with evolution to a severe encephalopathy, including progressive myoclonic epilepsy (PME). A more specific syndrome characterised by the association of CD, epilepsy, and occipital calcifications (CEC) has also been reported. This study describes the clinical, neuroradiological and neurophysiological features of eight consecutive epileptic patients with a diagnosis of CD confirmed by laboratory tests and duodenal biopsy, referring to our Epilepsy Centre. Despite its small size, this series reflects the broad spectrum of the association between the two diseases, since it includes four cases of CEC and a more heterogeneous group of patients without cerebral calcifications comprising one case of limbic encephalitis and a case of PME. Our cohort suggests that more complex pathogenic mechanisms may be involved in the association between epilepsy and CD, and that CD should be included in the screening for PME etiology. Our data also confirm the major involvement of the occipital lobe, and minimise both the importance of calcifications in epileptogenesis and folic acid deficit in the development of calcifications.

  6. Low calcification in corals in the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-10-01

    Reef-building coral communities in the Great Barrier Reef—the world's largest coral reef—may now be calcifying at only about half the rate that they did during the 1970s, even though live coral cover may not have changed over the past 40 years, a new study finds. In recent decades, coral reefs around the world, home to large numbers of fish and other marine species, have been threatened by such human activities as pollution, overfishing, global warming, and ocean acidification; the latter affects ambient water chemistry and availability of calcium ions, which are critical for coral communities to calcify, build, and maintain reefs. Comparing data from reef surveys during the 1970s, 1980s, and 1990s with present-day (2009) measurements of calcification rates in One Tree Island, a coral reef covering 13 square kilometers in the southern part of the Great Barrier Reef, Silverman et al. show that the total calcification rates (the rate of calcification minus the rate of dissolution) in these coral communities have decreased by 44% over the past 40 years; the decrease appears to stem from a threefold reduction in calcification rates during nighttime.

  7. Inflammatory, metabolic, and genetic mechanisms of vascular calcification

    PubMed Central

    Demer, Linda L.; Tintut, Yin

    2014-01-01

    This review centers on updating the active research area of vascular calcification. This pathology underlies substantial cardiovascular morbidity and mortality, through adverse mechanical effects on vascular compliance, vasomotion, and, most likely, plaque stability. Biomineralization is a complex, regulated process occurring widely throughout nature. Decades ago, its presence in the vasculature was considered a mere curiosity and an unregulated, “dystrophic” process that does not involve biological mechanisms. While it remains controversial whether the process has any adaptive value or past evolutionary advantage, substantial advances have been made in understanding the biological mechanisms driving the process. Different types of calcific vasculopathy, such as inflammatory vs. metabolic, have parallel mechanisms in skeletal bone calcification, such as intramembranous and endochondral ossification. Recent work has identified important regulatory roles for inflammation, oxidized lipids, elastin, alkaline phosphatase, osteoprogenitor cells, matrix gamma-carboxyglutamic acid protein (MGP), transglutaminase, osteoclastic regulatory factors, phosphate regulatory hormones and receptors, apoptosis, prelamin A, autophagy, and microvesicles or microparticles similar to the matrix vesicles of skeletal bone. Recent work has uncovered fascinating interactions between MGP, vitamin K, warfarin and transport proteins. And, lastly, recent breakthroughs in inherited forms of calcific vasculopathy, have identified the genes responsible as well as an unexpected overlap of phenotypes. PMID:24665125

  8. Acute calcific periarthritis outside the shoulder: a frequently misdiagnosed condition.

    PubMed Central

    Johnson, G S; Guly, H R

    1994-01-01

    Thirteen patients presented to an accident and emergency (A&E) department with acute calcific periarthritis of joints other than the shoulder. In only three patients was the correct diagnosis made on the initial attendance with inappropriate treatment and delay in recovery as a result. The specific features and guidelines for management of this condition are reviewed. Images Fig. 1 PMID:7804591

  9. Aortic Calcification: An Early Sign of Heart Valve Problems?

    MedlinePlus

    ... Rekha Mankad, M.D. References AskMayoExpert. Valvular disease – aortic stenosis. Rochester, Minn.: Mayo Foundation for Medical Education and ... Original article: http://www.mayoclinic.org/diseases-conditions/aortic-stenosis/expert-answers/aortic-valve-calcification/FAQ-20058525 . Mayo ...

  10. Coronary artery calcification in chronic kidney disease: An update

    PubMed Central

    Stompór, Tomasz

    2014-01-01

    Arterial calcification is a well-recognized complication of advanced atherosclerosis. Chronic kidney disease (CKD) is characterized by significantly more pronounced, disseminated and fast-progressing calcification of the vascular system, including the coronary arteries. New computed tomography-based imaging techniques allow for the noninvasive assessment and monitoring of calcification in different vascular sites. Coronary artery calcification (CAC) develops early in the course of CKD and is tightly associated with mineral and bone disorders, which include but are not limited to secondary hyperparathyroidism. In this review, recent data on the pathogenesis of CAC development and progression are discussed, with a special emphasis on fibroblast growth factor 23 and its co-receptor, klotho. The prevalence, progression and prognostic significance of CAC are reviewed separately for patients with end-stage renal disease treated with dialysis, kidney transplant recipients and patients with earlier stages of CKD. In the last section, therapeutic considerations are discussed, with special attention paid to the importance of treatment that addresses mineral and bone disorders of CKD. PMID:24772252

  11. Influence of Water content of RF and Microwave Dielectric Properties of Foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ABSTRACT The importance of dielectric properties of food materials is discussed with respect to their influence on the heating of materials by radio-frequency and microwave energy and their use for rapid, nondestructive sensing of quality characteristics of such materials. Data are presented graph...

  12. Influence of formulation and preparation process on ambroxol hydrochloride dry powder inhalation characteristics and aerosolization properties.

    PubMed

    Ren, Yachao; Yu, Chaoqun; Meng, Kangkang; Tang, Xing

    2008-09-01

    The objective of this study is to evaluate the influence of formulation and preparation process on ambroxol hydrochloride (AH) dry powder inhalation (DPI) characteristics and aerosolization properties. Spray-dried samples of AH, AH/leucine, and AH/leucine/mannitol were prepared from their corresponding water solutions under the same conditions to study the influence of the composition, and the AH/leucine/mannitol (2.5/0.5/1 by weight) formulation was used for investigation of the effect of the preparation process. Following spray-drying, the resulting powders were characterized using scanning electron microscopy, laser diffraction, tapped density, and angle of repose measurements, and the aerosolization performance was determined using a twin-stage liquid impinger. AH/leucine/mannitol (2.5/0.5/1 by weight) obtained by cospray-drying improved the AH aerosolization properties. The AH/leucine/mannitol (2.5/0.5/1 by weight) preparation exhibited the following properties: 62.34% yield, 0.34 g/cm(3) tap density, 2.71 microm d(ae), 33.45 degrees angle of repose, and 30.93% respirable fraction. The influence of the preparation process on DPI characteristics and aerosolization properties was relatively small, but the influence of the composition was relatively large. Optimization of DPI can be achieved by selecting the most appropriate formulation and preparation process.

  13. Molecular characterization of biochars and their influence on microbiological properties of soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The composition and surface chemistry of carbon rich biochar materials is highly uncertain and believed to change with feedstock and biomass conversion process. The tentative connection between the biochar surface chemical properties and their influence on microbially mediated mineralization of C, N...

  14. Analysis of the influence of the mode type on microstrip antenna directive properties

    NASA Astrophysics Data System (ADS)

    Bem, Daniel J.; Katulski, Ryszard J.

    The subject of this paper is the analysis of the mode type influence on the directive properties of a microstrip antenna with a rectangular radiating element. Investigations in this field were carried out using the aperture model of the antenna. The results of numerical investigations are presented.

  15. Evaluating the influence of residual stresses on the magnetic properties of electrical steel

    SciTech Connect

    Korzunin, G.S.; Chistyakov, V.K.

    1995-04-01

    The method described for evaluating the influence of residual stresses on the magnetic properties of coiled cold-rolled electrical steel consists in measuring the ratio of the magnetic characteristics that are and are not sensitive to the effect of residual stresses. The evaluation is made from the value of the ratio, using the correlations between its value and the magnetic characteristics studied.

  16. The Influence of Structural Optimization on the Aeroelastic Properties of a Vertical Tail

    DTIC Science & Technology

    1992-12-01

    ENY/92D-24 THE INFLUENCE OF STRUCTURAL OPTIMIZATION ON THE AEROELASTIC PROPERTIES OF A VERTICAL TAIL Acceso For THESIS NTIS CRA&I DTIC TAB David G...kernel function is an integral function which does not have a closed form solution due to multiple order singularities in the integrand. Therefore

  17. Influence of jet-cooking Prowashonupana barley flour on phenolic composition, antioxidant activities, and viscoelastic properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of jet-cooking Prowashonupana barley flour on total phenolic contents, antioxidant activities, water holding capacities, and viscoelastic properties was studied. Barley flour was jet-cooked without or with pH adjustment at 7, 9, or 11. Generally, the free phenolic content and antioxi...

  18. Influence of the refractive index and dispersion of spectacle lens on its imaging properties

    NASA Astrophysics Data System (ADS)

    Miks, Antonin; Novak, Jiri; Novak, Pavel

    2007-12-01

    The paper shows an influence of the refractive index and dispersion of the spectacle lens on its imaging properties. Relations are presented for calculation of radii of curvature of anastigmatic spectacle lenses and their chromatic aberration. Moreover, the formulas are derived for calculation of the change of astigmatism of spectacle lens due to dispersion of spectacle lens material.

  19. The influence of surface functionalisation on the electrical properties and thermal stability of nanodiamonds

    SciTech Connect

    Welch, Joseph O; Li, Pei; Chaudhary, Aysha; Edgington, Robert; Jackman, Richard B.

    2014-10-07

    Detonation nanodiamond (ND) has recently emerged as a useful new class of diamond material. However, to date there has been little investigation of the electrical properties of this material. Due to the nanoscale dimensions, the surface functionalisation of the individual ND is of particular importance to the characteristics of ND films. Here, hydrogen and oxygen termination of ND, verified using Fourier transform infrared spectroscopy, are shown to strongly influence the electronic properties of NDs. Hydrogen terminated ND exhibiting a far greater resilience to thermal decomposition when compared to the oxygen terminated NDs. Moreover, H-NDs also displayed so-called “surface conductivity,” a property displayed by hydrogen-terminated bulk diamond films, whilst O-NDs display properties high resistivity. These results indicate that under the correct conditions ND layers can display similar electrical properties to “bulk” diamond thin films.

  20. Quantification of Calcified Particles in Human Valve Tissue Reveals Asymmetry of Calcific Aortic Valve Disease Development

    PubMed Central

    Yabusaki, Katsumi; Hutcheson, Joshua D.; Vyas, Payal; Bertazzo, Sergio; Body, Simon C.; Aikawa, Masanori; Aikawa, Elena

    2016-01-01

    Recent studies indicated that small calcified particles observable by scanning electron microscopy (SEM) may initiate calcification in cardiovascular tissues. We hypothesized that if the calcified particles precede gross calcification observed in calcific aortic valve disease (CAVD), they would exhibit a regional asymmetric distribution associated with CAVD development, which always initiates at the base of aortic valve leaflets adjacent to the aortic outflow in a region known as the fibrosa. Testing this hypothesis required counting the calcified particles in histological sections of aortic valve leaflets. SEM images, however, do not provide high contrast between components within images, making the identification and quantification of particles buried within tissue extracellular matrix difficult. We designed a new unique pattern-matching based technique to allow for flexibility in recognizing particles by creating a gap zone in the detection criteria that decreased the influence of non-particle image clutter in determining whether a particle was identified. We developed this flexible pattern particle-labeling (FpPL) technique using synthetic test images and human carotid artery tissue sections. A conventional image particle counting method (preinstalled in ImageJ) did not properly recognize small calcified particles located in noisy images that include complex extracellular matrix structures and other commonly used pattern-matching methods failed to detect the wide variation in size, shape, and brightness exhibited by the particles. Comparative experiments with the ImageJ particle counting method demonstrated that our method detected significantly more (p < 2 × 10−7) particles than the conventional method with significantly fewer (p < 0.0003) false positives and false negatives (p < 0.0003). We then applied the FpPL technique to CAVD leaflets and showed a significant increase in detected particles in the fibrosa at the base of the leaflets (p

  1. Influence of alkali cation on the mechanical properties and durability of fly ash based geopolymers.

    PubMed

    Nikolić, Irena; Zejak, Radomir; Jankovič-Častvan, Ivona; Karanović, Ljiljana; Radmilović, Vuk; Radmilović, Velimir

    2013-01-01

    This research has provided information about the influence of alkali cations (Na+ and K+) on the mechanical properties and durability of fly ash based geopolymers. The results have shown that alkali cations have a strong influence on the mechanical properties of fly ash based geopolymers. K-geopolymers generally reach a higher value of compressive strength in comparison to Na- geopolymers. On the other hand, microstructure and phase composition of fly ash based geopolymers are not influenced by the nature of alkali cations. The ratio of main gel structure forming elements is practically not affected by the nature of alkali cations. Durability of fly ash based geopolymers in different aquatic environments is greatly dependent on the choice of alkali cations. Na- geopolymers are generally more resistant in water and aggressive environments than the K-geopolymers. The best durability of fly ash based geopolymers was observed in sea water.

  2. Antibacterial Properties of Copper Nanoparticle Dispersions: Influence of Synthesis Conditions and Physicochemical Characteristics

    NASA Astrophysics Data System (ADS)

    Godymchuk, A.; Frolov, G.; Gusev, A.; Zakharova, O.; Yunda, E.; Kuznetsov, D.; Kolesnikov, E.

    2015-11-01

    The production of bactericidal plasters, bandages and medicines with the inclusion of copper nanoparticles and copper ions may have a great potential in terms of their biomedical application. The work considers the influence of the synthesis conditions, size, aggregation status, and charge of nanoparticles in aqueous solutions as well as the type of microorganisms to the antibacterial properties of water suspensions of electroexplosive copper nanoparticles in the conditions in vitro in relation to strains Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus. Water dispersions of copper nanoparticles were shown to inhibit the growth of test cells for both G+ and G- microbacteria but the degree of such an influence strongly depended on the type of a test strain. The authors have demonstrated that use of deeply purified water and alcohol-containing stabilizers at the synthesis of nanoparticles via metals electric erosion in the liquid prevents the copper nanoparticles coagulation and significantly influences on their physicochemical characteristics and, consequently, antibacterial properties.

  3. Influence of process variables on the properties of laccase biobleached pulps.

    PubMed

    Martin-Sampedro, Raquel; Miranda, Jesús; García-Fuentevilla, Luisa L; Hernández, Manuel; Arias, Maria E; Diaz, Manuel J; Eugenio, Maria E

    2015-01-01

    A laccase stage can be used as a pre-treatment of a standard chemical bleaching sequence to reduce environmental concerns associated to this process. The importance of each independent variable and its influence on the properties of the bleached pulp have been studied in depth in this work, using an adaptive network-based fuzzy inference system (ANFIS) with four independent variables (laccase, buffer, mediator and oxygen) as input. Eucalyptus globulus kraft pulp was biobleached using a laccase from Pycnoporus sanguineus and a natural mediator (acetosyringone). Later, an alkaline extraction and a hydrogen peroxide treatment were applied. Most biobleaching processes showed a decrease in kappa number and an increase in brightness with no significant impact on the viscosity values, compared with the control. Oxygen was the variable with the smallest influence on the final pulp properties while the laccase and buffer solution showed a significant influence.

  4. Influence Of The Laser Cladding Strategies On The Mechanical Properties Of Inconel 718

    SciTech Connect

    Lamikiz, A.; Tabernero, I.; Ukar, E.; Lopez de Lacalle, L. N.

    2011-01-17

    This work presents different experimental results of the mechanical properties of Inconel registered 718 test parts built-up by laser cladding. Recently, turbine manufacturers for aeronautical sector have presented high interest on laser cladding processes. This process allows building fully functional structures on superalloys, such as Inconel registered 718, with high flexibility on complex shapes. However, there is limited data on mechanical properties of the laser cladding structures. Moreover, the available data do not include the influence of process parameters and laser cladding strategies. Therefore, a complete study of the influence of the laser cladding parameters and mainly, the variation of the tensile strength with the laser cladding strategy is presented. The results show that there is a high directionality of mechanical properties, depending on the strategies of laser cladding process. In other words, the test parts show a fiber -like structure that should be considered on the laser cladding strategy selection.

  5. Influence Of The Laser Cladding Strategies On The Mechanical Properties Of Inconel 718

    NASA Astrophysics Data System (ADS)

    Lamikiz, A.; Tabernero, I.; Ukar, E.; López de Lacalle, L. N.; Delgado, J.

    2011-01-01

    This work presents different experimental results of the mechanical properties of Inconel® 718 test parts built-up by laser cladding. Recently, turbine manufacturers for aeronautical sector have presented high interest on laser cladding processes. This process allows building fully functional structures on superalloys, such as Inconel® 718, with high flexibility on complex shapes. However, there is limited data on mechanical properties of the laser cladding structures. Moreover, the available data do not include the influence of process parameters and laser cladding strategies. Therefore, a complete study of the influence of the laser cladding parameters and mainly, the variation of the tensile strength with the laser cladding strategy is presented. The results show that there is a high directionality of mechanical properties, depending on the strategies of laser cladding process. In other words, the test parts show a fiber -like structure that should be considered on the laser cladding strategy selection.

  6. Evidence for effectiveness of Extracorporal Shock-Wave Therapy (ESWT) to treat calcific and non-calcific rotator cuff tendinosis--a systematic review.

    PubMed

    Huisstede, Bionka M A; Gebremariam, Lukas; van der Sande, Renske; Hay, Elaine M; Koes, Bart W

    2011-10-01

    Extracorporeal shock-wave therapy (ESWT) is suggested as a treatment alternative for calcific and non-calcific rotator cuff tendinosis (RC-tendinosis), which may decrease the need for surgery. In this study we assessed the evidence for effectiveness of ESWT for these disorders. The Cochrane Library, PubMed, Embase, Pedro, and Cinahl were searched for relevant systematic reviews and RCTs. Two reviewers independently extracted data and assessed the methodological quality. Seventeen RCTs (11 calcific, 6 non-calcific) were included. For calcific RC-tendinosis, strong evidence was found for effectiveness in favour of high-ESWT versus low-ESWT in short-term. Moderate evidence was found in favour of high-ESWT versus placebo in short-, mid- and long-term and versus low-ESWT in mid- and long-term. Moreover, high-ESWT was more effective (moderate evidence) with focus on calcific deposit versus focus on tuberculum major in short- and long-term. RSWT was more effective (moderate evidence) than placebo in mid-term. For non-calcific RC-tendinosis, no strong or moderate evidence was found in favour of low-, mid- or high-ESWT versus placebo, each other, or other treatments. This review shows that only high-ESWT is effective for treating calcific RC-tendinosis. No evidence was found for the effectiveness of ESWT to treat non-calcific RC-tendinosis.

  7. Kangaroo vs. porcine aortic valves: calcification potential after glutaraldehyde fixation.

    PubMed

    Narine, K; Chéry, Cyrille C; Goetghebeur, Els; Forsyth, R; Claeys, E; Cornelissen, Maria; Moens, L; Van Nooten, G

    2005-01-01

    The aim of this study was to evaluate and compare the calcification potential of kangaroo and porcine aortic valves after glutaraldehyde fixation at both low (0.6%) and high (2.0%) concentrations of glutaraldehyde in the rat subcutaneous model. To our knowledge this is the first report comparing the time-related, progressive calcification of these two species in the rat subcutaneous model. Twenty-two Sprague-Dawley rats were each implanted with two aortic valve leaflets (porcine and kangaroo) after fixation in 0.6% glutaraldehyde and two aortic valve leaflets (porcine and kangaroo) after fixation in 2% glutaraldehyde respectively. Animals were sacrificed after 24 h and thereafter weekly for up to 10 weeks after implantation. Calcium content was determined using inductively coupled plasma-mass spectrometry and confirmed histologically. Mean calcium content per milligram of tissue (dry weight) treated with 0.6 and 2% glutaraldehyde was 116.2 and 110.4 microg/mg tissue for kangaroo and 95.0 and 106.8 microg/mg tissue for porcine valves. Calcium content increased significantly over time (8.8 microg/mg tissue per week) and was not significantly different between groups. Regression analysis of calcification over time showed no significant difference in calcification of valves treated with 0.6 or 2% glutaraldehyde within and between the two species. Using the subcutaneous model, we did not detect a difference in calcification potential between kangaroo and porcine aortic valves treated with either high or low concentrations of glutaraldehyde.

  8. Coral Calcification Across a Natural Gradient in Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Cohen, A. L.; Brainard, R. E.; Young, C.; Shamberger, K. E.; McCorkle, D. C.; Feely, R. A.; Mcleod, E.; Cantin, N.; Rose, K.; Lohmann, G. P.

    2011-12-01

    Much of our understanding of the impact of ocean acidification on coral calcification comes from laboratory manipulation experiments in which corals are reared under a range of seawater pH and aragonite saturation states (μar) equivalent to those projected for the next hundred years. In general, experiments show a consistently negative impact of acidification on coral calcification, leading to predictions of mass coral reef extinctions by dissolution as natural rates of carbonate erosion exceed the rates at which corals and other reef calcifiers can replace it. The tropical oceans provide a natural laboratory within which to test hypotheses about the longer term impact and adaptive potential of corals to acidification of the reef environment. Here we report results of a study in which 3-D CT scan and imaging techniques were used to quantify annual rates of calcification by conspecifics at 12 reefs sites spanning a natural gradient in ocean acidification. In situ μar calculated from alkalinity and DIC measurements of reef seawater ranged from less than 2.7 on an eastern Pacific Reef to greater than 4.0 in the central Red Sea. No correlation between μar and calcification was observed across this range. Corals living on low μar reefs appear to be calcifying as fast, sometimes faster than conspecifics living on high μar reefs. We used total lipid and tissue thickness to index the energetic status of colonies collected at each of our study sites. Our results support the hypothesis that energetics plays a key role in the coral calcification response to ocean acidification. Indeed, the true impact of acidification on coral reefs will likely be felt as temperatures rise and the ocean becomes more stratified, depleting coral energetic reserves through bleaching and reduced nutrient delivery to oceanic reefs.

  9. Mammographic calcification cluster detection and threshold gold thickness measurements

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Mackenzie, A.; Cooke, J.; Given-Wilson, R.; Wallis, M. G.; Chakraborty, D. P.; Dance, D. R.; Young, K. C.

    2012-03-01

    European Guidelines for quality control in digital mammography specify acceptable and achievable standards of image quality (IQ) in terms of threshold gold thickness using the CDMAM test object. However, there is little evidence relating such measurements to cancer detection. This work investigated the relationship between calcification detection and threshold gold thickness. An observer study was performed using a set of 162 amorphous selenium direct digital (DR) detector images (81 no cancer and 81 with 1-3 inserted calcification clusters). From these images four additional IQs were simulated: different digital detectors (computed radiography (CR) and DR) and dose levels. Seven observers marked and rated the locations of suspicious regions. DBM analysis of variances was performed on the JAFROC figure of merit (FoM) yielding 95% confidence intervals for IQ pairs. Automated threshold gold thickness (Tg) analysis was performed for the 0.25mm gold disc diameter on CDMAM images at the same IQs (16 images per IQ). Tg was plotted against FoM and a power law fitted to the data. There was a significant reduction in FoM for calcification detection for CR images compared with DR; FoM decreased from 0.83 to 0.63 (p<=0.0001). Detection was also sensitive to dose. There was a good correlation between FoM and Tg (R2=0.80, p<0.05), consequently threshold gold thickness was a good predictor of calcification detection at the same IQ. Since the majority of threshold gold thicknesses for the various IQs were above the acceptable standard despite large variations in calcification detection by radiologists, current EU guidelines may need revising.

  10. A gender bias in the calcification response to ocean acidification

    NASA Astrophysics Data System (ADS)

    Holcomb, M.; Cohen, A. L.; McCorkle, D. C.

    2011-08-01

    The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. No nutrient effect was observed. At 16 °C, gamete release was not observed, and no gender differences in calcification rate were observed. However, corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns. Female corals grown at 24 °C and exposed to CO2 had calcification rates 39 % lower than females grown at ambient CO2, while males showed only a 5 % decline in calcification under elevated CO2. At 16 °C, female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15 % and 19 % respectively). At 24 °C, corals spawned repeatedly, while no spawning was observed at 16 °C. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification and their inclusion in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.

  11. Calcification by juvenile corals under heterotrophy and elevated CO2

    NASA Astrophysics Data System (ADS)

    Drenkard, E. J.; Cohen, A. L.; McCorkle, D. C.; de Putron, S. J.; Starczak, V. R.; Zicht, A. E.

    2013-09-01

    Ocean acidification (OA) threatens the existence of coral reefs by slowing the rate of calcium carbonate (CaCO3) production of framework-building corals thus reducing the amount of CaCO3 the reef can produce to counteract natural dissolution. Some evidence exists to suggest that elevated levels of dissolved inorganic nutrients can reduce the impact of OA on coral calcification. Here, we investigated the potential for enhanced energetic status of juvenile corals, achieved via heterotrophic feeding, to modulate the negative impact of OA on calcification. Larvae of the common Atlantic golf ball coral, Favia fragum, were collected and reared for 3 weeks under ambient (421 μatm) or significantly elevated (1,311 μatm) CO2 conditions. The metamorphosed, zooxanthellate spat were either fed brine shrimp (i.e., received nutrition from photosynthesis plus heterotrophy) or not fed (i.e., primarily autotrophic). Regardless of CO2 condition, the skeletons of fed corals exhibited accelerated development of septal cycles and were larger than those of unfed corals. At each CO2 level, fed corals accreted more CaCO3 than unfed corals, and fed corals reared under 1,311 μatm CO2 accreted as much CaCO3 as unfed corals reared under ambient CO2. However, feeding did not alter the sensitivity of calcification to increased CO2; ∆ calcification/∆Ω was comparable for fed and unfed corals. Our results suggest that calcification rates of nutritionally replete juvenile corals will decline as OA intensifies over the course of this century. Critically, however, such corals could maintain higher rates of skeletal growth and CaCO3 production under OA than those in nutritionally limited environments.

  12. Detection of calcifications in vivo and ex vivo after brain injury in rat using SWIFT.

    PubMed

    Lehto, Lauri Juhani; Sierra, Alejandra; Corum, Curtis Andrew; Zhang, Jinjin; Idiyatullin, Djaudat; Pitkänen, Asla; Garwood, Michael; Gröhn, Olli

    2012-07-16

    Calcifications represent one component of pathology in many brain diseases. With MRI, they are most often detected by exploiting negative contrast in magnitude images. Calcifications are more diamagnetic than tissue, leading to a magnetic field disturbance that can be seen in phase MR images. Most phase imaging studies use gradient recalled echo based pulse sequences. Here, the phase component of SWIFT, a virtually zero acquisition delay sequence, was used to detect calcifications ex vivo and in vivo in rat models of status epilepticus and traumatic brain injury. Calcifications were detected in phase and imaginary SWIFT images based on their dipole like magnetic field disturbances. In magnitude SWIFT images, calcifications were distinguished as hypointense and hyperintense. Hypointense calcifications showed large crystallized granules with few surrounding inflammatory cells, while hyperintense calcifications contained small granules with the presence of more inflammatory cells. The size of the calcifications in SWIFT magnitude images correlated with that in Alizarin stained histological sections. Our data indicate that SWIFT is likely to better preserve signal in the proximity of a calcification or other field perturber in comparison to gradient echo due to its short acquisition delay and broad excitation bandwidth. Furthermore, a quantitative description for the phase contrast near dipole magnetic field inhomogeneities for the SWIFT pulse sequence is given. In vivo detection of calcifications provides a tool to probe the progression of pathology in neurodegenerative diseases. In particular, it appears to provide a surrogate marker for inflammatory cells around the calcifications after brain injury.

  13. Pre-Existing Venous Calcification Prior to Dialysis Vascular Access Surgery

    PubMed Central

    Lee, Timmy; Safdar, Nida; Mistry, Meenakshi J; Wang, Yang; Chauhan, Vibha; Campos, Begoña; Munda, Rino; Cornea, Virgilius; Roy-Chaudhury, Prabir

    2014-01-01

    Vascular calcification is present in arterial vessels used for dialysis vascular access creation prior to surgical creation. Calcification in the veins used to create a new vascular access has not previously been documented. The objective of this study was to describe the prevalence of venous calcification in samples collected at the time of vascular access creation. 67 vein samples were studied. A von Kossa stain was performed to quantify calcification. A semi-quantitative scoring system from 0–4+ was used to quantify the percentage positive area for calcification as a fraction of total area (0=0; 1+ = 1–10%; 2+ =11–25%; 3+ = 26–50%; 4+ >50% positive). 22/67(33%) samples showed evidence of venous calcification. Histologic examination showed varying degrees of calcification within each cell layer. Among the subset of patients with calcification, 4/22 (18%), 19/22 (86%), 22/22 (100%), and 7/22 (32%) had calcification present within the endothelium, intima, media, and adventitia, respectively. The mean semi-quantitative scores of the 22 samples with calcification were 0.18±0.08, 1.2±0.14, 1.6±0.13, and 0.36±0.12 for the endothelium, intima, media, and adventitia, respectively. Our results demonstrate that vascular calcification is present within veins used to create new dialysis vascular access, and located predominately within the neointimal and medial layers. PMID:22452638

  14. The effects of decellularization and cross-linking techniques on the fatigue life and calcification of mitral valve chordae tendineae.

    PubMed

    Gunning, Gillian M; Murphy, Bruce P

    2016-04-01

    In cases of severely diseased mitral valves (MV), the required treatment is often valve replacement. Bioprosthetic and stentless replacement valves are usually either fully or partially composed of animal derived tissue treated with a decellularization process, a cross-linking process, or both. In this study, we analysed the effects of these treatments on the fatigue properties of porcine MV chordae tendineae (CT), as well as on the calcification of the CT using an in vitro technique. CT were tested in 4 groups; (1) native, (2) decellularized (DC), (3) decellularized and cross-linked with glutaraldehyde (DC-GTH), and (4) decellularized and cross-linked with 1-ehtyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)(DC-EDC). CT were tested in both uniaxial tension, and in fatigue at 10MPa peak stress (1Hz). The cycles to failure (mean±SD) for the four groups are as follows; Native- 53,397±55,798, DC- 28,013±30,634, DC-GTH- 97,665±133,556, DC-EDC- 318,601±322,358. DC-EDC CT were found to have a slightly longer fatigue life than the native and DC groups. The DC-EDC group also had a marginally lower dynamic creep rate, meaning those CT elongate more slowly. After in vitro calcification, X-ray microtomography was used to determine relative levels of calcification. The DC-EDC and DC-GTH groups had the lowest volume of calcific deposits. Under uniaxial testing, the ultimate tensile strength (UTS) of the DC-GTH CT was statistically significantly reduced after calcification, while the UTS was relatively unchanged for the DC-EDC group. Overall, these results indicate that a treatment of decellularization plus cross-linking with EDC may improve the fatigue life of porcine CT, reduce the rate of elongation, and help the CT resist the negative effects of calcification. This may be a preferable treatment in the preparation of porcine MVs for the replacement of diseased MVs.

  15. Differential Effects of Ocean Acidification on Coral Calcification: Insights from Geochemistry.

    NASA Astrophysics Data System (ADS)

    Holcomb, M.; Decarlo, T. M.; Venn, A.; Tambutte, E.; Gaetani, G. A.; Tambutte, S.; Allemand, D.; McCulloch, M. T.

    2014-12-01

    Although ocean acidification is expected to negatively impact calcifying animals due to the formation of CaCO3 becoming less favorable, experimental evidence is mixed. Corals have received considerable attention in this regard; laboratory culture experiments show there to be a wide array of calcification responses to acidification. Here we will show how relationships for the incorporation of various trace elements and boron isotopes into synthetic aragonite can be used to reconstruct carbonate chemistry at the site of calcification. In turn the chemistry at the site of calcification can be determined under different ocean acidification scenarios and differences in the chemistry at the site of calcification linked to different calcification responses to acidification. Importantly we will show that the pH of the calcifying fluid alone is insufficient to estimate calcification responses, thus a multi-proxy approach using multiple trace elements and isotopes is required to understand how the site of calcification is affected by ocean acidification.

  16. Cardiac Fibroblasts Adopt Osteogenic Fates and Can Be Targeted to Attenuate Pathological Heart Calcification.

    PubMed

    Pillai, Indulekha C L; Li, Shen; Romay, Milagros; Lam, Larry; Lu, Yan; Huang, Jie; Dillard, Nathaniel; Zemanova, Marketa; Rubbi, Liudmilla; Wang, Yibin; Lee, Jason; Xia, Ming; Liang, Owen; Xie, Ya-Hong; Pellegrini, Matteo; Lusis, Aldons J; Deb, Arjun

    2017-02-02

    Mammalian tissues calcify with age and injury. Analogous to bone formation, osteogenic cells are thought to be recruited to the affected tissue and induce mineralization. In the heart, calcification of cardiac muscle leads to conduction system disturbances and is one of the most common pathologies underlying heart blocks. However the cell identity and mechanisms contributing to pathological heart muscle calcification remain unknown. Using lineage tracing, murine models of heart calcification and in vivo transplantation assays, we show that cardiac fibroblasts (CFs) adopt an osteoblast cell-like fate and contribute directly to heart muscle calcification. Small-molecule inhibition of ENPP1, an enzyme that is induced upon injury and regulates bone mineralization, significantly attenuated cardiac calcification. Inhibitors of bone mineralization completely prevented ectopic cardiac calcification and improved post injury heart function. Taken together, these findings highlight the plasticity of fibroblasts in contributing to ectopic calcification and identify pharmacological targets for therapeutic development.

  17. Ocean acidification induces biochemical and morphological changes in the calcification process of large benthic foraminifera

    PubMed Central

    Prazeres, Martina; Uthicke, Sven; Pandolfi, John M.

    2015-01-01

    Large benthic foraminifera are significant contributors to sediment formation on coral reefs, yet they are vulnerable to ocean acidification. Here, we assessed the biochemical and morphological impacts of acidification on the calcification of Amphistegina lessonii and Marginopora vertebralis exposed to different pH conditions. We measured growth rates (surface area and buoyant weight) and Ca-ATPase and Mg-ATPase activities and calculated shell density using micro-computer tomography images. In A. lessonii, we detected a significant decrease in buoyant weight, a reduction in the density of inner skeletal chambers, and an increase of Ca-ATPase and Mg-ATPase activities at pH 7.6 when compared with ambient conditions of pH 8.1. By contrast, M. vertebralis showed an inhibition in Mg-ATPase activity under lowered pH, with growth rate and skeletal density remaining constant. While M. vertebralis is considered to be more sensitive than A. lessonii owing to its high-Mg-calcite skeleton, it appears to be less affected by changes in pH, based on the parameters assessed in this study. We suggest difference in biochemical pathways of calcification as the main factor influencing response to changes in pH levels, and that A. lessonii and M. vertebralis have the ability to regulate biochemical functions to cope with short-term increases in acidity. PMID:25694619

  18. Physical oceanographic processes influence bio-optical properties in the Tasman Sea

    NASA Astrophysics Data System (ADS)

    Cherukuru, Nagur; Davies, Peter L.; Brando, Vittorio E.; Anstee, Janet M.; Baird, Mark E.; Clementson, Lesley A.; Doblin, Martina A.

    2016-04-01

    Remote sensing observations show optical signatures to conform to the physical oceanographic patterns in the Tasman Sea. To test the link between physical oceanographic processes and bio-optical properties we investigated an in situ bio-optical dataset collected in the Tasman Sea. Analysis of in situ observations showed the presence of four different water masses in the Tasman Sea, formed by the relatively warm and saline East Australia Current (EAC) water, a mesoscale cold core eddy on the continental slope, cooler Tasman Sea water on the shelf and river plume water. The distribution of suspended substances and their inherent optical properties in these water masses were distinctly different. Light absorption and attenuation budgets indicate varying optical complexity between the water masses. Specific inherent optical properties of suspended particulate and dissolved substances in each group were different as they were influenced by physical and biogeochemical processes specific to that water mass. Remote sensing reflectance signature varied in response to changing bio-optical properties between the water masses; thus providing the link between physical oceanographic processes, bio-optical properties and the optical signature. Findings presented here extend our knowledge of the Tasman Sea, its optical environment and the role of physical oceanographic processes in influencing the inherent optical properties and remote sensing signature in this complex oceanographic region.

  19. Environmental and management influences on temporal variability of near saturated soil hydraulic properties.

    PubMed

    Bodner, G; Scholl, P; Loiskandl, W; Kaul, H-P

    2013-08-01

    Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (- 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r(2) = 0.43 to 0.59). Our results suggested that beside considering average

  20. MicroRNA-32 promotes calcification in vascular smooth muscle cells: Implications as a novel marker for coronary artery calcification

    PubMed Central

    Shen, Yingying; Chen, Ling; Xu, Canxin; Zhao, Heng; Wu, Ying; Zhang, Qinghai; Zhong, Jing; Tang, Zhenwang; Liu, Changhui; Zhao, Qiang; Zheng, Yi; Cao, Renxian; Zu, Xuyu

    2017-01-01

    Cardiovascular calcification is one of the most severe outcomes associated with cardiovascular disease and often results in significant morbidity and mortality. Previous reports indicated that epigenomic regulation of microRNAs (miRNAs) might play important roles in vascular smooth muscle cell (VSMC) calcification. Here, we identified potential key miRNAs involved in vascular calcification in vivo and investigated the role of miR-32-5p (miR-32). According to microarray analysis, we observed increased expression of miR-125b, miR-30a, and miR-32 and decreased expression of miR-29a, miR-210, and miR-320 during the progression of vascularcalcification. Additionally, gain- and loss-of-function studies of miR-32 confirmed promotion of VSMC calcification in mice through the enhanced expression of bonemorphogenetic protein-2, runt-related transcription factor-2(RUNX2), osteopontin, and the bone-specific phosphoprotein matrix GLA protein in vitro. Moreover, miR-32 modulated vascularcalcification progression by activating phosphoinositide 3-kinase (PI3K)signaling and increasing RUNX2 expression and phosphorylation by targeting the 3′-untranslated region of phosphatase and tensin homolog Mrna (PTEN) in mouse VSMCs. Furthermore, we detected higher miR-32 levels in plasmafrom patients with coronary artery disease with coronary artery calcification (CAC) as compared with levels observed in non-CAC patients (P = 0.016), further confirming miR-32 as a critical modulator and potential diagnostic marker for CAC. PMID:28319142

  1. The Sensitivity of Marine Calcification to carbonate ion concentration

    NASA Astrophysics Data System (ADS)

    Langdon, C.

    2006-12-01

    It is now well established that the rate of calcification of biogenic calcification is a function of the carbonate ion concentration. This relationship has been best established in the case of corals. Data is now available for twelve species. For the purpose of comparison it is convenient to normalize the calcification rates to the rate achieved at the pre-industrial carbonate ion concentration of the surface tropical ocean taken for the purposes of this analysis to be 255 μmol kg-1. If the rates from all the available studies are processed in this way and then regressed against the carbonate ion concentration one obtains that the normalized calcification = -24.5+0.47[CO32-], r#2=0.74. From this relationship one can calculate that at the present time the rate of coral calcification may have declined by 19% relative to the pre-industrial rate and by the end of the century, if pCO2 reaches 700 μatm, it could decline by 54%. This assumes that any rise in sea surface temperature does not have a significant effect on coral calcification. At the present time this is a major source of uncertainty. Several studies show that corals are adapted to the mean annual temperature that they experience and the rate of calcification during the summer is depressed relative to the maximal rates observed during the spring and fall. In this scenario any increase in the mean annual temperature will result in a reduced annual rate of calcification. These studies show that the rate of calcification falls off at the rate of 24±17 % per °C once the temperature exceeds the species thermal optimum. Other studies based on long-lived massive corals widely used in paleo-climate reconstructions exhibit a linear relationship with temperature that shows no sign of tapering off at the highest temperatures for which data are available. At this time we do not know which pattern is more representative of the aggregate response of corals on a typical coral reef. It should not be forgotten that

  2. Observations of Three-Dimensional Radiative Effects that Influence Satellite Retrievals of Cloud Properties

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander; Lau, William K. M. (Technical Monitor)

    2001-01-01

    This paper examines three-dimensional (3D) radiative effects, which arise from horizontal radiative interactions between areas that have different cloud properties. Earlier studies have argued that these effects can cause significant uncertainties in current satellite retrievals of cloud properties, because the retrievals rely on one-dimensional (1D) theory and do not consider the effects of horizontal changes in cloud properties. This study addresses two questions: which retrieved cloud properties are influenced by 3D radiative effects, and where 3D effects tend to occur? The influence of 3D effects is detected from the wayside illumination and shadowing make clouds appear asymmetric: Areas appear brighter if the cloud top surface is tilted toward, rather than away from, the Sun. The analysis of 30 images by the Moderate Resolution Imaging Spectroradiometer (MODIS) reveals that retrievals of cloud optical thickness and cloud water content are most influenced by 3D effects, whereas retrievals of cloud particle size are much less affected. The results also indicate that while 3D effects are strongest at cloud edges, cloud top variability in cloud interiors, even in overcast regions, also produces considerable 3D effects. Finally, significant 3D effects are found in a wide variety of situations, ranging from thin clouds to thick ones and from low clouds to high ones.

  3. The influence of Reynolds numbers on resistance properties of jet pumps

    NASA Astrophysics Data System (ADS)

    Geng, Q.; Zhou, G.; Li, Q.

    2014-01-01

    Jet pumps are widely used in thermoacoustic Stirling heat engines and pulse tube cryocoolers to eliminate the effect of Gedeon streaming. The resistance properties of jet pumps are principally influenced by their structures and flow regimes which are always characterized by Reynolds numbers. In this paper, the jet pump of which cross section contracts abruptly is selected as our research subject. Based on linear thermoacoustic theory, a CFD model is built and the oscillating flow of the working gas is simulated and analyzed with different Reynolds numbers in the jet pump. According to the calculations, the influence of different structures and Reynolds numbers on the resistance properties of the jet pump are analyzed and presented. The results show that Reynolds numbers have a great influence on the resistance properties of jet pumps and some empirical formulas which are widely used are unsuitable for oscillating flow with small Reynolds numbers. This paper provides a more comprehensive understanding on resistance properties of jet pumps with oscillating flow and is significant for the design of jet pumps in practical thermoacoustic engines and refrigerators.

  4. [Influence of physico-chemical properties of materials on the postcompressional parameters of tablets].

    PubMed

    Sovány, Tamás; Hódi, Klára

    2014-01-01

    The number of tablets marketed with a score line to aid divisibility is increasing. The subdivision of scored tablets in order to ensure dose flexibility may be an easier and cheaper solution from the aspect of production. However, to ensure the appropriate mechanical properties and divisibility of tablets so as to guarantee consequent dosing is a difficult problem, which is influenced by many properties of the applied materials, such as the physicochemical behaviour, the plasticity, the degree of elasticity, the mechanism of compression, etc. These exert a significant influence on the postcompressional properties of tablets, and hence on the subdivision of tablets. Despite the considerable difficulties, the increasing importance in paediatrics and the ever stricter requirements of the drug authorities, the subdivision of scored tablets is a poorly studied field. This paper deals with the influence of physico-chemical properties of materials on the postcompressional parameters of tablets, and especially on the subdivision of tablets. For measurement of the force required to break tablets into halves, a laboratory-constructed hardness tester was utilized.

  5. The influence of Reynolds numbers on resistance properties of jet pumps

    SciTech Connect

    Geng, Q.; Zhou, G.; Li, Q.

    2014-01-29

    Jet pumps are widely used in thermoacoustic Stirling heat engines and pulse tube cryocoolers to eliminate the effect of Gedeon streaming. The resistance properties of jet pumps are principally influenced by their structures and flow regimes which are always characterized by Reynolds numbers. In this paper, the jet pump of which cross section contracts abruptly is selected as our research subject. Based on linear thermoacoustic theory, a CFD model is built and the oscillating flow of the working gas is simulated and analyzed with different Reynolds numbers in the jet pump. According to the calculations, the influence of different structures and Reynolds numbers on the resistance properties of the jet pump are analyzed and presented. The results show that Reynolds numbers have a great influence on the resistance properties of jet pumps and some empirical formulas which are widely used are unsuitable for oscillating flow with small Reynolds numbers. This paper provides a more comprehensive understanding on resistance properties of jet pumps with oscillating flow and is significant for the design of jet pumps in practical thermoacoustic engines and refrigerators.

  6. Vitamin D Receptor Deficiency and Low Vitamin D Diet Stimulate Aortic Calcification and Osteogenic Key Factor Expression in Mice

    PubMed Central

    Schmidt, Nadine; Brandsch, Corinna; Kühne, Hagen; Thiele, Alexandra; Hirche, Frank; Stangl, Gabriele I.

    2012-01-01

    Low levels of 25-hydroxy vitamin D (25(OH)D) are associated with cardiovascular diseases. Herein, we tested the hypothesis that vitamin D deficiency could be a causal factor in atherosclerotic vascular changes and vascular calcification. Aortic root sections of vitamin D receptor knockout (VDR−/−) mice that were stained for vascular calcification and immunostained for osteoblastic differentiation factors showed more calcified areas and a higher expression of the osteogenic key factors Msx2, Bmp2, and Runx2 than the wild-type mice (P<0.01). Data from LDL receptor knockout (LDLR−/−) mice that were fed western diet with either low (50 IU/kg), recommended (1,000 IU/kg), or high (10,000 IU/kg) amounts of vitamin D3 over 16 weeks revealed increasing plasma concentrations of 25(OH)D (P<0.001) with increasing intake of vitamin D, whereas levels of calcium and phosphorus in plasma and femur were not influenced by the dietary treatment. Mice treated with the low vitamin D diet had more calcified lesions and a higher expression of Msx2, Bmp2, and Runx2 in aortic roots than mice fed recommended or high amounts of vitamin D (P<0.001). Taken together, these findings indicate vitamin D deficiency as a risk factor for aortic valve and aortic vessel calcification and a stimulator of osteogenic key factor expression in these vascular areas. PMID:22536373

  7. Calcification response of Pleurochrysis carterae to iron concentrations in batch incubations: implication for the marine biogeochemical cycle

    NASA Astrophysics Data System (ADS)

    Zou, Xiang; Sun, Shiyong; Lin, Sen; Shen, Kexuan; Dong, Faqin; Tan, Daoyong; Nie, Xiaoqin; Liu, Mingxue; Wei, Jie

    2017-03-01

    Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form of coccoliths located on the cell surface. Using batch incubations of the coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm (parts per million), 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon (coccoliths), and organic carbon (organic cellular components) showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization-enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.

  8. Direct Synthesis and Morphological Characterization of Gold-Dendrimer Nanocomposites Prepared Using PAMAM Succinamic Acid Dendrimers: Preliminary Study of the Calcification Potential

    PubMed Central

    Vasile, E.; Serafim, A.; Petre, D.; Giol, D.; Dubruel, P.; Iovu, H.; Stancu, I. C.

    2014-01-01

    Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated. PMID:24600316

  9. Analysis of corrugated cardboard influence on the protective properties of complex packaging system

    NASA Astrophysics Data System (ADS)

    Osowski, Przemyslaw; Piatkowski, Tomasz

    2017-03-01

    According to available literature, it is assumed that outer packaging container, which is usually made of corrugated cardboard, does not influence the mitigation of the impact effects, thus in the designing process of packaging system the outer packaging is skipped. The purpose of this paper is to verify the above assumption, including determination of the influence of the 5-layer cardboard on the properties of structures that consist of that cardboard and polyethylene foam. Verification is performed with the use of the finite element method. To apply this method the dynamic compression curve of cushioning material is required. Therefore in the paper it is also presented the modified method to determine the curve.

  10. Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2016-04-01

    The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates.

  11. Coccolithophores on the north-west European shelf: calcification rates and environmental controls

    NASA Astrophysics Data System (ADS)

    Poulton, A. J.; Stinchcombe, M. C.; Achterberg, E. P.; Bakker, D. C. E.; Dumousseaud, C.; Lawson, H. E.; Lee, G. A.; Richier, S.; Suggett, D. J.; Young, J. R.

    2014-02-01

    Coccolithophores are a key functional group in terms of the pelagic production of calcium carbonate (calcite), although their contribution to shelf-sea biogeochemistry, and how this relates to environmental conditions, is poorly constrained. Measurements of calcite production (CP) and coccolithophore abundance were made on the north-west European shelf to examine trends in coccolithophore calcification along natural gradients of carbonate chemistry, macronutrient availability and plankton composition. Similar measurements were also made in three bioassay experiments where nutrient (nitrate, phosphate) and pCO2 levels were manipulated. Nanoflagellates (< 10 μm) dominated chlorophyll biomass and primary production (PP) at all but one sampling site, with CP ranging from 0.6-9.6 mmol C m-2d-1. Highest CP and coccolithophore cell abundance occurred in a diatom bloom in fully mixed waters off Helgoland, rather than in two distinct coccolithophore blooms in the central North Sea and Western English Channel. Estimates of coccolithophore contributions to total PP and nanoplankton PP were generally < 5%, apart from in a coccolithophore bloom at the Western English Channel Observatory (E1) where coccolithophores contributed up to 11% and at Helgoland where they contributed ~23% to nanoplankton PP. Variability in CP was influenced by cell numbers, species composition and cell-normalised calcification rates under both in situ conditions and in the experimental bioassays. Water column structure and light availability had a strong influence on cellular calcification, whereas nitrate (N) to phosphate (P) ratios influenced bulk CP. Coccolithophore communities in the northern North Sea and over the Norwegian Trench showed responses to N and P addition whereas oceanic communities in the Bay of Biscay showed no response. Sharp decreases in pH and a rough halving of calcite saturation states in the bioassay experiments led to decreased CP in the Bay of Biscay and Northern North Sea

  12. Salient material properties and haptic volume perception: the influences of surface texture, thermal conductivity, and compliance.

    PubMed

    Bergmann Tiest, Wouter M; Kahrimanovic, Mirela; Niemantsverdriet, Ilona; Bogale, Kassahun; Kappers, Astrid M L

    2012-11-01

    We investigated the influences of surface texture, thermal conductivity, and compliance on the haptic perception of the volume of small cubes. It was hypothesized that an object containing highly salient material properties would be perceived as larger in volume than the same object without these properties. Blindfolded subjects were asked to explore pairs of cubes differing in their material properties and to select the one with the larger volume. The results showed that, counterintuitively, a smooth cube was perceived as being significantly larger than a rough cube of the same physical volume, with average biases of about 19 %. Furthermore, cubes with a higher thermal conductivity were perceived as significantly larger than cubes with a lower thermal conductivity (average bias of about 7 %). In addition, the magnitude of the bias in this condition was not changed by increasing or decreasing the temperature of the test objects, suggesting that the effect of thermal conductivity could not be attributed directly to the heat flow. Finally, a hard cube was perceived as significantly larger than a soft cube of equal physical volume, with an average bias of about 25 %. These results reveal that the studied material properties have significant and consistent influences on the haptic perception of volume. The observed biases provide an indication of the levels at which the processing of haptic information on volume and material properties occurs.

  13. Influence of pre-stress fields on electric properties of semiconductor nanowires

    SciTech Connect

    Zhu, Linli

    2015-03-10

    The effects of pre-stress field on the electric properties such as electron-acoustic phonon interaction and mobility are investigated for a rectangular silicon nanowire. The continuum elastic model is employed to calculate the spatially confined phonon dispersion relation. The electron-acoustic phonon scattering rate and the carrier mobility are obtained for stressed silicon nanowire. The numerical results show that the pre-stress field has a significant influence on the phonon properties, leading to completely altering the electron-acoustic phonon interaction. Under the tensile (compressive) pre-stress, the carrier mobility is reduced (enhanced) that is sensitive to the strength of corresponding stress fields.

  14. Influence of sputtering power on the optical properties of ITO thin films

    SciTech Connect

    K, Aijo John; M, Deepak T, Manju; Kumar, Vineetha V.

    2014-10-15

    Tin doped indium oxide films are widely used in transparent conducting coatings such as flat panel displays, crystal displays and in optical devices such as solar cells and organic light emitting diodes due to the high electrical resistivity and optical transparency in the visible region of solar spectrum. The deposition parameters have a commendable influence on the optical and electrical properties of the thin films. In this study, ITO thin films were prepared by RF magnetron sputtering. The properties of the films prepared under varying sputtering power were compared using UV- visible spectrophotometry. Effect of sputtering power on the energy band gap, absorption coefficient and refractive index are investigated.

  15. Influence of excess diamine on properties of PMR polyimide resins and composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, F. I.

    1980-01-01

    This preliminary study explores the influence of 1-10 percent molar excess MDA on the molecular weight distribution and rheological properties of an imidized PMR system. Molecular weight distribution is characterized by gel permeation chromatography of the imidized molding compound; shear viscosity is related to changes in average molecular weight. The thermo-oxidative stability at 600 F glass transition temperature, flexural and interlaminar shear properties of PMR polyimide/Celion 6000 graphite fiber composites are compared as a function of the percent excess MDA in the monomer reactant mixture.

  16. Influence of Heat Treatment on Mechanical Properties of DLC Deposited by FIB-CVD

    NASA Astrophysics Data System (ADS)

    Sakamoto, Naomichi; Kogo, Yasuo; Yasuno, Takuya; Taniguchi, Jun; Miyamoto, Iwao

    The influence of heat treatment on the mechanical properties of DLC deposited by FIB-CVD was examined. To evaluate the mechanical properties, Young’s modulus and Vickers hardness were measured by the nano indentation tester. For the characterization of DLC structure, Raman scattering was used. The microstructures of samples were characterized by HRTEM equipped with EELS. From results of the indentation experiments, it was found that Young’s modulus and Vickers hardness decreased with increasing heat treatment temperature. Analysis of Raman and EELS spectra indicated that the decrease of Young’s modulus and hardness was caused by the decrease of sp3 fraction.

  17. Influence of gaseous annealing environment on the properties of indium-tin-oxide thin films

    NASA Astrophysics Data System (ADS)

    Wang, R. X.; Beling, C. D.; Fung, S.; Djurišić, A. B.; Ling, C. C.; Li, S.

    2005-02-01

    The influence of postannealing in different gaseous environments on the optical properties of indiu-tin-oxide (ITO) thin films deposited on glass substrates using e-beam evaporation has been systematically investigated. It is found that the annealing conditions affect the optical and electrical properties of the films. Atomic force microscopy, x-ray diffraction, and x-ray photoemission spectroscopy (XPS) were employed to obtain information on the chemical state and crystallization of the films. These data suggest that the chemical states and surface morphology of the ITO film are strongly influenced by the gaseous environment during the annealing process. The XPS data indicate that the observed variations in the optical transmittance can be explained by oxygen incorporation into the film, decomposition of the indium oxide phases, as well as the removal of metallic In.

  18. Influence of perennial plants on chemical properties of arid calcareous soils in Iran

    SciTech Connect

    Karimian, N.; Razmi, K. )

    1990-10-01

    The authors conducted a study in Bajgah to determine the influence of perennial plants on some selected properties of soils formed on the highly calcareous parent material. The major plant genera were determined to be Agropyron, Artemisia, Astragalus, Dianthus, Eryngium, Peganum, Polygonum, Stipa, and Thymus. Tops of plants genera were found to be significantly different in ash, N, P, K, Ca, Mg, Na, Mn, Zn, and Cu; the concentration of Fe was not significantly different. The authors found the plants to differ significantly in their influence on soil properties. Peganum caused an accumulation of organic matter (OM) as high as 7% in the soil, in an environment where the soils typically contain less than 1% OM. Soil concentrations of P, K, Mn, Zn, and Cu were also found to vary significantly beneath different plant genera. They suggest these differences in OM accumulation were caused by plant litter. Concentration of Fe in the soils formed beneath different plant genera was statistically unchanged.

  19. Influence of glass composition on the properties of glass polyalkenoate cements. Part III: influence of fluorite content.

    PubMed

    De Barra, E; Hill, R G

    2000-03-01

    The influence of fluorite content of the glass on the formation and properties of glass polyalkenoate cements was investigated. A series of glass powders based on 1.5SiO2 x 0.5P2O5 x Al2O3 x CaO x XCaF2 were synthesised. The glass transition temperature of the glass fell with increasing fluorite content. Setting and working times of the cement pastes decreased with increasing fluorite content of the glass. Compressive strength and un-notched fracture strength increased with increasing fluorite content of the glass. Fracture toughness and toughness of the cements were relatively insensitive to fluorite content.

  20. Influence of Zwitterions on Thermomechanical Properties and Morphology of Acrylic Copolymers: Implications for Electroactive Applications

    DTIC Science & Technology

    2011-09-30

    properties of ethyl acrylate and n-butyl acrylate ( nBA )-based sulfobetaine-containing copolymers.10,11 They found that the incorporation of...ammonio]-1-propanesulfonate (SBMA), a zwitterionic mono- mer. Copolymerization of both charge-containing monomers with nBA elucidates the influence of...3-[[2-(methacryloyloxy)ethyl]- (dimethyl)ammonio]-1-propanesulfonate (SBMA), was generously provided by Raschig GmbH. n-Butyl acrylate ( nBA , Alfa

  1. Influence of thermal treatment on magnetocaloric properties of Gd cold rolled ribbons

    NASA Astrophysics Data System (ADS)

    Taskaev, Sergey V.; Buchelnikov, Vasiliy D.; Pellenen, Anatoliy P.; Kuz'min, Michael D.; Skokov, Konstantin P.; Karpenkov, Dmitry Yu.; Bataev, Dmitry S.; Gutfleisch, Oliver

    2013-05-01

    This work reports the influence of heat treatment on the magnetocaloric effect of cold-rolled Gd ribbons. A significant depression of magnetic and thermodynamical properties occurs in severely deformed ribbons. However, it is possible to recover the initial values, characteristic of polycrystals by way of heat treatment. The heat treatment regimes are directly connected with the degree of plastic deformation. The proposed approach is convenient for manufacturing magnetocaloric materials in the form of thin ribbons for magnetic refrigerators.

  2. Influence of PVP in magnetic properties of NiSn nanoparticles prepared by polyol method

    NASA Astrophysics Data System (ADS)

    Bobadilla, L. F.; García, C.; Delgado, J. J.; Sanz, O.; Romero-Sarria, F.; Centeno, M. A.; Odriozola, J. A.

    2012-11-01

    The influence of PVP on the magnetic properties of NiSn nanoparticles prepared by polyol method has been studied. NiSn nanoparticles exhibit superparamagnetic behavior although there is a ferromagnetic contribution due to particles agglomerated below the blocking temperature. The particle size is controlled by the addiction of PVP in varying amounts. The addition of PVP also favours the particles isolation, narrow the particle size distribution and decrease the interparticle interaction strength increasing the superparamagnetic contribution.

  3. Beyond the Alphabet Soup: Molecular Properties of Aerosol Components Influence Optics. (Invited)

    NASA Astrophysics Data System (ADS)

    Thompson, J. E.

    2013-12-01

    Components within atmospheric aerosols exhibit almost every imaginable model of chemical bonding and physical diversity. The materials run the spectrum from crystalline to amorphous, covalent to ionic, and have varying viscosities, phase, and hygroscopicity. This seminar will focus on the molecular properties of materials that influence the optical behavior of aerosols. Special focus will be placed on the polarizability of materials, hygroscopic growth, and particle phase.

  4. The influence of nano-ceramic modifier on the structure and properties of polyolefin composites

    NASA Astrophysics Data System (ADS)

    Sudnik, L.; Dubkova, V.; Galinovsky, A.; Osipkov, A.

    2016-10-01

    It has been shown, that the nano-ceramic modifier boehmite, with specific surface area of up to 400 m2/g and dispersion degree of less than100 nm, is a structurally active filler of an ultra-high-molecular-weight polyethylene. The boehmite influences the polymer crystalline and supra-molecular structure, during crystallization of the polymer from the melt under uniaxial plastic deformation conditions. It results in the production of nano-composites with an improved complex of properties.

  5. Grazing season and forage type influence goat milk composition and rennet coagulation properties.

    PubMed

    Inglingstad, R A; Steinshamn, H; Dagnachew, B S; Valenti, B; Criscione, A; Rukke, E O; Devold, T G; Skeie, S B; Vegarud, G E

    2014-01-01

    Two different types of pasture (cultivated and rangeland) and 2 different hay qualities (high and low quality) were examined for their effects on goat milk composition and rennet coagulation properties. Furthermore, the effect of dietary treatments in both the early and late grazing season was studied. As lactation stage is known to influence milk composition, the goats in the early and late grazing season were in the same lactation stage at the start of the experiment. The milk composition was influenced both by dietary treatment and season. Milk from goats on pasture was superior to those on hay by containing a higher content of protein and casein, and the goats on cultivated pasture had the highest milk yield. Casein composition was significantly influenced by forage treatment. Goats grazing on cultivated pasture had higher contents of αs1-casein and also of κ-casein compared with the other treatments, whereas goats grazing on rangeland had the highest content of β-casein. Factors such as milk yield, casein micelle size, αs2-casein, and calcium content were reduced in late compared with early season. More favorable rennet coagulation properties were achieved in milk from the early grazing season, with shorter firming time and higher curd firmness compared with milk from the late grazing season, but the firming time and curd firmness were not prominently influenced by forage treatment. The content of αs2-casein and calcium in the milk affected the firming time and the curd firmness positively. The influence of season and forage treatment on especially milk yield, casein content, and rennet coagulation properties is of economic importance for both the dairy industry and goat milk farmers.

  6. Phytoplankton calcification in a high-CO2 world.

    PubMed

    Iglesias-Rodriguez, M Debora; Halloran, Paul R; Rickaby, Rosalind E M; Hall, Ian R; Colmenero-Hidalgo, Elena; Gittins, John R; Green, Darryl R H; Tyrrell, Toby; Gibbs, Samantha J; von Dassow, Peter; Rehm, Eric; Armbrust, E Virginia; Boessenkool, Karin P

    2008-04-18

    Ocean acidification in response to rising atmospheric CO2 partial pressures is widely expected to reduce calcification by marine organisms. From the mid-Mesozoic, coccolithophores have been major calcium carbonate producers in the world's oceans, today accounting for about a third of the total marine CaCO3 production. Here, we present laboratory evidence that calcification and net primary production in the coccolithophore species Emiliania huxleyi are significantly increased by high CO2 partial pressures. Field evidence from the deep ocean is consistent with these laboratory conclusions, indicating that over the past 220 years there has been a 40% increase in average coccolith mass. Our findings show that coccolithophores are already responding and will probably continue to respond to rising atmospheric CO2 partial pressures, which has important implications for biogeochemical modeling of future oceans and climate.

  7. Low Florida coral calcification rates in the Plio-Pleistocene

    NASA Astrophysics Data System (ADS)

    Brachert, Thomas C.; Reuter, Markus; Krüger, Stefan; Klaus, James S.; Helmle, Kevin; Lough, Janice M.

    2016-08-01

    In geological outcrops and drill cores from reef frameworks, the skeletons of scleractinian corals are usually leached and more or less completely transformed into sparry calcite because the highly porous skeletons formed of metastable aragonite (CaCO3) undergo rapid diagenetic alteration. Upon alteration, ghost structures of the distinct annual growth bands often allow for reconstructions of annual extension ( = growth) rates, but information on skeletal density needed for reconstructions of calcification rates is invariably lost. This report presents the bulk density, extension rates and calcification rates of fossil reef corals which underwent minor diagenetic alteration only. The corals derive from unlithified shallow water carbonates of the Florida platform (south-eastern USA), which formed during four interglacial sea level highstands dated approximately 3.2, 2.9, 1.8, and 1.2 Ma in the mid-Pliocene to early Pleistocene. With regard to the preservation, the coral skeletons display smooth growth surfaces with minor volumes of marine aragonite cement within intra-skeletal porosity. Within the skeletal structures, voids are commonly present along centres of calcification which lack secondary cements. Mean extension rates were 0.44 ± 0.19 cm yr-1 (range 0.16 to 0.86 cm yr-1), mean bulk density was 0.96 ± 0.36 g cm-3 (range 0.55 to 1.83 g cm-3) and calcification rates ranged from 0.18 to 0.82 g cm-2 yr-1 (mean 0.38 ± 0.16 g cm-2 yr-1), values which are 50 % of modern shallow-water reef corals. To understand the possible mechanisms behind these low calcification rates, we compared the fossil calcification rates with those of modern zooxanthellate corals (z corals) from the Western Atlantic (WA) and Indo-Pacific calibrated against sea surface temperature (SST). In the fossil data, we found a widely analogous relationship with SST in z corals from the WA, i.e. density increases and extension rate decreases with increasing SST, but over a significantly larger

  8. Low Florida coral calcification rates in the Plio-Pleistocene

    NASA Astrophysics Data System (ADS)

    Brachert, T. C.; Reuter, M.; Krüger, S.; Klaus, J. S.; Helmle, K.; Lough, J. M.

    2015-12-01

    In geological outcrops and drill cores from reef frameworks, the skeletons of scleractinian corals are usually leached and more or less completely transformed into sparry calcite because the highly porous skeletons formed of metastable aragonite (CaCO3) undergo rapid diagenetic alteration. Upon alteration, ghost structures of the distinct annual growth bands may be retained allowing for reconstructions of annual extension (= growth) rates, but information on skeletal density needed for reconstructions of calcification rates is invariably lost. Here we report the first data of calcification rates of fossil reef corals which escaped diagenetic alteration. The corals derive from unlithified shallow water carbonates of the Florida platform (southeastern USA), which formed during four interglacial sea level highstands dated 3.2, 2.9, 1.8, and 1.2 Ma in the mid Pliocene to early Pleistocene. With regard to the preservation, the coral skeletons display smooth growth surfaces with minor volumes of marine aragonite cement within intra-skeletal porosity. Within the skeletal structures, dissolution is minor along centers of calcification. Mean extension rates were 0.44 ± 0.19 cm yr-1 (range 0.16 to 0.86 cm yr-1) and mean bulk density was 0.86 ± 0.36 g cm-3 (range 0.55 to 1.22 g cm-3). Correspondingly, calcification rates ranged from 0.18 to 0.82 g cm-2 yr-1 (mean 0.38 ± 0.16 g cm-2 yr-1), values which are 50 % of modern shallow-water reef corals. To understand the possible mechanisms behind these low calcification rates, we compared the fossil calcification with modern zooxanthellate-coral (z-coral) rates from the Western Atlantic (WA) and Indo-Pacific (IP) calibrated against sea surface temperature (SST). In the fossil data, we found an analogous relationship with SST in z-corals from the WA, i.e. density increases and extension rate decreases with increasing SST, but over a significantly larger temperature window during the Plio-Pleistocene. With regard to the

  9. Insights on the Optical Properties of Estuarine DOM – Hydrological and Biological Influences

    PubMed Central

    Santos, Luísa; Pinto, António; Filipe, Olga; Cunha, Ângela; Santos, Eduarda B. H.

    2016-01-01

    Dissolved organic matter (DOM) in estuaries derives from a diverse array of both allochthonous and autochthonous sources. In the estuarine system Ria de Aveiro (Portugal), the seasonality and the sources of the fraction of DOM that absorbs light (CDOM) were inferred using its optical and fluorescence properties. CDOM parameters known to be affected by aromaticity and molecular weight were correlated with physical, chemical and meteorological parameters. Two sites, representative of the marine and brackish water zones of the estuary, and with different hydrological characteristics, were regularly surveyed along two years, in order to determine the major influences on CDOM properties. Terrestrial-derived compounds are the predominant source of CDOM in the estuary during almost all the year and the two estuarine zones presented distinct amounts, as well as absorbance and fluorescence characteristics. Freshwater inputs have major influence on the dynamics of CDOM in the estuary, in particular at the brackish water zone, where accounted for approximately 60% of CDOM variability. With a lower magnitude, the biological productivity also impacted the optical properties of CDOM, explaining about 15% of its variability. Therefore, climate changes related to seasonal and inter-annual variations of the precipitation amounts might impact the dynamics of CDOM significantly, influencing its photochemistry and the microbiological activities in estuarine systems. PMID:27195702

  10. Moss Mediates the Influence of Shrub Species on Soil Properties and Processes in Alpine Tundra

    PubMed Central

    Williamson, Scott N.; Barrio, Isabel C.; Helgadóttir, Ágústa; HiK, David S.

    2016-01-01

    In tundra ecosystems, bryophytes influence soil processes directly and indirectly through interactions with overstory shrub species. We experimentally manipulated moss cover and measured seasonal soil properties and processes under two species of deciduous shrubs with contrasting canopy structures, Salix planifolia pulchra and Betula glandulosa-nana complex. Soil properties (seasonal temperature, moisture and C:N ratios) and processes (seasonal litter decomposition and soil respiration) were measured over twelve months. Shrub species identity had the largest influence on summer soil temperatures and soil respiration rates, which were higher under Salix canopies. Mosses were associated with lower soil moisture irrespective of shrub identity, but modulated the effects of shrubs on winter soil temperatures and soil C:N ratios so that moss cover reduced differences in soil winter temperatures between shrub species and reduced C:N ratios under Betula but not under Salix canopies. Our results suggest a central role of mosses in mediating soil properties and processes, with their influence depending on shrub species identity. Such species-dependent effects need to be accounted for when forecasting vegetation dynamics under ongoing environmental changes. PMID:27760156

  11. Influence of sodium hypochlorite on mechanical properties of K3 nickel-titanium rotary instruments.

    PubMed

    Ormiga Galvão Barbosa, Fabiola; Antônio da Cunha Ponciano Gomes, José; Pimenta de Araújo, Marcos Cesar

    2007-08-01

    Several studies have evaluated the influence of various factors on the fracture of nickel-titanium endodontic rotary instruments. The present study analyzed the influence of sodium hypochlorite on flexural fatigue and torsional properties of nickel-titanium endodontic rotary instruments. New files and files previously exposed to sodium hypochlorite were tested for flexural fatigue and for resistance to fracture by twisting. The t test was used to compare the groups for number of cycles, angle of rotation, and maximum torque required to fracture. No statistical difference existed between these groups. Scanning electron microscopy analysis showed no evidence of localized corrosion in files exposed to sodium hypochlorite solution. These results suggest that the exposure to sodium hypochlorite has no influence on resistance to fracture of K3 rotary instruments.

  12. Modelling coral polyp calcification in relation to ocean acidification

    NASA Astrophysics Data System (ADS)

    Hohn, S.; Merico, A.

    2012-11-01

    Rising atmospheric CO2 concentrations due to anthropogenic emissions induce changes in the carbonate chemistry of the oceans and, ultimately, a drop in ocean pH. This acidification process can harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. It is expected that ocean acidification in combination with other anthropogenic stressors will cause a severe decline in coral abundance by the end of this century, with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calcifying fluid. Precipitation of calcium carbonate takes place in the metabolically controlled calcifying fluid beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. We find that a transport mechanism for bicarbonate is required to supplement carbon into the calcifying fluid because CO2 diffusion alone is not sufficient to sustain the observed calcification rates. Simulated CO2 perturbation experiments reveal decreasing calcification rates under elevated pCO2 despite the strong metabolic control of the calcifying fluid. Diffusion of CO2 through the tissue into the calcifying fluid increases with increasing seawater pCO2, leading to decreased aragonite saturation in the calcifying fluid. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

  13. High blood pressure in pregnancy and coronary calcification.

    PubMed

    Sabour, Siamak; Franx, Arie; Rutten, Annemarieke; Grobbee, Diederick E; Prokop, Mathias; Bartelink, Marie-Louise; van der Schouw, Yvonne T; Bots, Michiel L

    2007-04-01

    A considerable proportion of pregnant women develop high blood pressure in pregnancy. Although it is assumed that this condition subsides after pregnancy, many of these women develop the metabolic syndrome later in life and are at increased risk to develop coronary heart disease. Atherosclerosis development is considered in between risk factors and occurrence of vascular symptoms. We set out to cross-sectionally study the relation of high blood pressure during pregnancy with risk of coronary calcification. The study population was composed 491 healthy postmenopausal women selected from a population-based cohort study. Information on high blood pressure during pregnancy was obtained using a questionnaire. Between 2004 and 2005, the women underwent a multidetector computed tomography (Philips Mx 8000 IDT 16) to assess coronary calcium. The Agatston score, volume, and mass measurements were used to quantify coronary calcium. A total of 30.7% of the women reported to have had high blood pressure in pregnancy. Body mass index (odds ratio [OR]: 1.05; 95% CI: 1.01 to 1.09) and diastolic blood pressure (OR: 1.03; 95% CI: 1.01 to 1.05) were significantly related to a history of high blood pressure in pregnancy. Age was significantly related to increased coronary calcification. Women with a history of high blood pressure during pregnancy had a 57% increased risk of having coronary calcification compared with those women without this condition (OR: 1.57; 95% CI: 1.04 to 2.37). After adjusting for age, the relation did not change (OR: 1.64; 95% CI: 1.07 to 2.53). We concluded that high blood pressure during pregnancy is associated with an increased risk of coronary calcification later in life.

  14. Stone formation and calcification by nanobacteria in the human body

    NASA Astrophysics Data System (ADS)

    Ciftcioglu, Neva; Bjorklund, Michael; Kajander, E. Olavi

    1998-07-01

    The formation of discrete and organized inorganic crystalline structures within macromolecular extracellular matrices is a widespread biological phenomenon generally referred to as biomineralization. Recently, bacteria have been implicated as factors in biogeochemical cycles for formation of many minerals in aqueous sediments. We have found nanobacterial culture systems that allow for reproducible production of apatite calcification in vitro. Depending on the culture conditions, tiny nanocolloid-sized particles covered with apatite, forming various size of aggregates and stones were observed. In this study, we detected the presence of nanobacteria in demineralized trilobit fossil, geode, apatite, and calcite stones by immunofluorescence staining. Amethyst and other quartz stones, and chalk gave negative results. Microorganisms are capable of depositing apatite outside the thermodynamic equilibrium in sea water. We bring now evidence that this occurs in the human body as well. Previously, only struvite kidney stones composed of magnesium ammonium phosphate and small amounts of apatite have been regarded as bacteria related. 90 percent of demineralized human kidney stones now screened, contained nanobacteria. At least three different distribution patterns of nanobacteria were conditions, and human kidney stones that are formed from small apatite units. Prerequisites for the formation of kidney stones are the supersaturation of urine and presence of nidi for crystallization. Nanobacteria are important nidi and their presence might be of special interest in space flights where supersaturation of urine is present due to the loss of bone. Furthermore, we bring evidence that nanobacteria may act as crystallization nidi for the formation of biogenic apatite structures in tissue calcification found in e.g., atherosclerotic plaques, extensive metastatic and tumoral calcification, acute periarthritis, malacoplakia, and malignant diseases. In nanaobacteria-infected fibroblasts

  15. Calcific Tendinitis of the Gluteus Maximus in a Golfer.

    PubMed

    Williams, Ariel A; Stang, Thomas S; Fritz, Jan; Papp, Derek F

    2016-09-01

    Calcific tendinitis is a relatively rare condition in which calcium is inappropriately deposited in tendons, resulting in a local inflammatory reaction that can cause severe symptoms in certain cases. The cause of this disease process is not completely understood, although repetitive microtrauma likely plays a role in its development. Although the disorder most often involves the rotator cuff, it can affect other structures throughout the body, such as the tendons about the ankle and hip-including the rectus femoris and gluteus maximus. Nonoperative management typically involves using an anti-inflammatory medication and activity modification and can be augmented with formal physical therapy and modalities. Although nonoperative management provides adequate relief for many patients, sometimes operative debridement of the calcific deposit with or without repair of the involved tendon is required. The authors report an unusual case of calcific tendinitis of the gluteus maximus insertion in a golfer. The patient had tried nonoperative treatment for approximately 2 years with no real relief, and a recent exacerbation of the pain was significantly delaying his return to sport. Although plain radiographs did not show abnormalities, magnetic resonance imaging showed a calcific deposit in the insertion of the gluteus maximus tendon. After discussing further treatment options with the patient, the decision was made to remove the deposit and repair the insertion. He recovered completely and was able to return to play. The frequency, pathogenesis, and treatment of this condition are discussed in this case report, as well as the possible link to golf in this patient. [Orthopedics.2016; 39(5):e997-e1000.].

  16. Gluteus maximus calcific tendonosis: a rare cause of sciatic pain.

    PubMed

    Singh, Jaspal R; Yip, Kevin

    2015-02-01

    Extraspinal causes of radicular pain are rare and are in danger of being overlooked. Here, we present a patient with pain radiating into the posterior thigh and lateral calf. Although initial differential diagnosis included lumbar herniated nucleus pulposus, further imaging revealed the presence of gluteus maximus calcific tendonosis. After physical therapy and a potent oral steroid regimen, the pain gradually resolved and the patient was able to return to full activity.

  17. Calcification of the external carotid arteries and their branches

    PubMed Central

    MacDonald, D S; Zhang, L; Gu, Y

    2012-01-01

    This patient had longstanding hypercalcaemia and hyperphosphataemia owing to chronic renal disease, then finally failure, inducing tertiary hyperparathyroidism. He also had long histories of diabetes mellitus type II, hypertension and hypercholesterolaemia. He then reported a painful expansile swelling of the anterior mandible which was diagnosed as a “brown tumour”. Subsequent review of the CT data set by an oral and maxillofacial radiologist revealed two patterns of calcification of the carotid arteries. A pipestem pattern was observed bilaterally along almost the entire lengths of the external carotid artery, a muscular artery, and its branches whereas plaque-like calcification was observed in the common and internal carotid arteries (elastic arteries). The pipestem pattern, hitherto an unreported feature affecting the external carotid artery, may represent a metastatic calcified deposit owing to hypercalcaemia and hyperphosphataemia in the tunica media of muscular arteries, resulting in arteriosclerosis, which maintains a patent lumen. The plaque-like pattern is representative of lumen-occluding calcified atherosclerosis associated with the long histories of diabetes mellitus type II, hypertension and hypercholesterolaemia. As this patient did not have any symptoms and/or signs of myofacial pain, facial dysfunction or numbness, the calcification of his external carotid arteries and branches were considered as arteriosclerosis. The brown tumour responded to the parathyroidectomy and the renal transplant. PMID:22241884

  18. Calcification of the external carotid arteries and their branches.

    PubMed

    Macdonald, D S; Zhang, L; Gu, Y

    2012-10-01

    This patient had longstanding hypercalcaemia and hyperphosphataemia owing to chronic renal disease, then finally failure, inducing tertiary hyperparathyroidism. He also had long histories of diabetes mellitus type II, hypertension and hypercholesterolaemia. He then reported a painful expansile swelling of the anterior mandible which was diagnosed as a "brown tumour". Subsequent review of the CT data set by an oral and maxillofacial radiologist revealed two patterns of calcification of the carotid arteries. A pipestem pattern was observed bilaterally along almost the entire lengths of the external carotid artery, a muscular artery, and its branches whereas plaque-like calcification was observed in the common and internal carotid arteries (elastic arteries). The pipestem pattern, hitherto an unreported feature affecting the external carotid artery, may represent a metastatic calcified deposit owing to hypercalcaemia and hyperphosphataemia in the tunica media of muscular arteries, resulting in arteriosclerosis, which maintains a patent lumen. The plaque-like pattern is representative of lumen-occluding calcified atherosclerosis associated with the long histories of diabetes mellitus type II, hypertension and hypercholesterolaemia. As this patient did not have any symptoms and/or signs of myofacial pain, facial dysfunction or numbness, the calcification of his external carotid arteries and branches were considered as arteriosclerosis. The brown tumour responded to the parathyroidectomy and the renal transplant.

  19. Transglutaminase inhibitors attenuate vascular calcification in a preclinical model

    PubMed Central

    Beazley, Kelly E.; Banyard, Derek; Lima, Florence; Deasey, Stephanie C.; Nurminsky, Dmitry I.; Konoplyannikov, Mikhail; Nurminskaya, Maria V.

    2012-01-01

    Objective In vitro, transglutaminase 2 (TG2)-mediated activation of the β-catenin signaling pathway is central in warfarin-induced calcification, warranting inquiry into the importance of this signaling axis as a target for preventive therapy of vascular calcification in vivo. Methods and Results The adverse effects of warfarin-induced elastocalcinosis in a rat model include calcification of the aortic media, loss of the cellular component in the vessel wall, and isolated systolic hypertension, associated with accumulation and activation of TG2 and activation of β-catenin signaling. These effects of warfarin can be completely reversed by intraperitoneal administration of the TG2-specific inhibitor KCC-009 or dietary supplementation with the bioflavonoid quercetin, known to inhibit β-catenin signaling. Our study also uncovers a previously uncharacterized ability of quercetin to inhibit TG2. Quercetin reversed the warfarin-induced increase in systolic pressure, underlying the functional consequence of this treatment. Molecular analysis shows that quercetin diet stabilizes the phenotype of smooth muscle and prevents its transformation into osteoblastic cells. Conclusions Inhibition of the TG2/β-catenin signaling axis appears to prevent warfarin-induced elastocalcinosis and to control isolated systolic hypertension. PMID:23117658

  20. [Hydroxyapatite rheumatism (multiple tendon calcification disease). I.- Clinical study].

    PubMed

    Amor, B; Cherot, A; Delbarre, F

    1977-05-01

    A study was made of 45 patients suffering from hydroxyapatite rheumatism (multiple tendon calcifications disease). There were 36 women and 9 men aged between 15 and 61 years with an average age of 14. The following joints were involved (the first figure refers to clinical affection, that between brackets to radiologically demonstrable calcifications): shoulder 34 (36); neck 14 (15); wrist 18 (11); fingers 19 (17); hip 11 (29); knee 14 (18); ankle 10 (14); foot 5 (6); spinal column 16 (24). In 30 patients the disease manifested itself in the form of acute recurrent migratory arthritis resembling gout. In 8 cases, it developed in the form of acute recurrent migratory arthritis resembling gout. In 8 cases, it developed in the form of acute polyarthritis and in 7 as rheumatoid arthritis without radiological lesions. Thirty-two patients could be followed up. Four of them were cured, 9 showed improvement but still suffered attacks of pain. Eighteen patients were not improved, their pains growing more chronic. Four patients had a family history of multiple tendon calcifications disease.

  1. Rheological properties of wheat starch influenced by amylose-lysophosphatidylcholine complexation at different gelation phases.

    PubMed

    Ahmadi-Abhari, S; Woortman, A J J; Hamer, R J; Loos, K

    2015-05-20

    Amylose is able to form helical inclusion complexes with lysophosphatidylcholine (LPC). This complexation influences the functional and rheological properties of wheat starch; however it is well known that the formation of these complexes lead the starchy systems to a slower enzymatic hydrolysis. Based on this, to benefit from both the structuring properties of starch and also lower digestibility of the inclusion complexes, the objective of this study is the formation of amylose-LPC inclusion complexes while developing a firm network providing the desired functional properties in a starchy system. To investigate the influence of amylose-LPC complex formation at different stages of starch gelation on the viscosity behavior of wheat starch, 3% (w/w) LPC was added at three different points of the viscosity profile, obtained by rapid visco analyzer (RVA). LPC addition at all points affected the gelation behavior of wheat starch as compared with the reference. LPC addition at half-peak and peak of the viscosity profile resulted in a viscosity increase during cooling. Measuring the dynamic rheological properties of the freshly prepared gelatinized samples showed a decrease of storage modulus (G') and loss modulus (G") in the presence of LPC. During storage, in the presence of LPC, a lower elasticity was observed which indicates a lower rate of amylose retrogradation due to complexation with LPC.

  2. An influence of a Glass Braze Composition on the Properties of Li-Ti Ferrite Joints

    NASA Astrophysics Data System (ADS)

    Lin, Panpan; Lin, Tiesong; He, Peng; Sekulic, Dusan P.; Zhao, Mengyuan; Wang, Shulei

    2017-04-01

    The influence of the chemical composition of Bi2O3-B2O3-SiO2-ZnO glass brazes on (i) the microstructure, (ii) the mechanical and (iii) the dielectric properties of Li-Ti ferrite joints was systematically investigated. The Bi5(Ti3Fe)O15 whisker and a white block phase consisting of Bi12SiO2 and Bi24B2O39 were observed in the joints of Li-Ti ferrite/Bi25-Ba and Li-Ti ferrite/glass brazes, respectively, containing a higher content of Bi2O3. No crystalline phase was detected in the Li-Ti ferrite/Bi25 and Li-Ti ferrite/Bi20 joints. The joint strength reached the maximum of 48 MPa in the Li-Ti ferrite/Bi25-Ba couples. It is assumed that this is mainly due to the strengthening effect of Bi5(Ti3Fe)O15 whiskers. The bonding temperature (700°C) had little effect on the dielectric properties of Li-Ti ferrite. Moreover, compared to the Bi25-Ba glass brazes, the Bi25 and Bi20 glass brazes had a less pronounced influence on the dielectric properties of joints. Different glass brazes can be tailored to different requirements depending on specific application and joint property requirements.

  3. Influence of flocculation and settling properties of activated sludge in relation to secondary settler performance.

    PubMed

    Wilén, B M; Onuki, M; Hermansson, M; Lumley, D; Mino, T

    2006-01-01

    Floc characteristics were studied at a full scale activated sludge treatment plant with a unique process solution incorporating pre-denitrification with post-nitrification in nitrifying trickling filters. Since greater nitrogen removal is achieved when more secondary settled wastewater is recirculated to the trickling filters, the secondary settlers are always operated close to their maximal capacity. The flocculation and settling properties are therefore crucial and have an effect on the overall plant performance. Since the plant is operated at a short sludge age, these properties change quickly, resulting in variable maximal secondary settler capacity. The dynamics in floc structure and microbial community composition were studied and correlated to the secondary settler performance. Fluorescence in situ hybridisation was used to investigate the microbial community structure and their spatial distribution. The floc structure could to some extent be related to the flocculation and settling properties of the sludge. Even small differences had an influence suggesting that colloidal properties also play a significant role in determining the floc properties. No correlation between microbial community composition and settling properties could be established with the group-specific probes investigated.

  4. Influence of hydroxypropylmethylcellulose addition and homogenization conditions on properties and ageing of corn starch based films.

    PubMed

    Jiménez, Alberto; Fabra, María José; Talens, Pau; Chiralt, Amparo

    2012-06-20

    Edible films based on corn starch, hydroxypropyl methylcellulose (HPMC) and their mixtures were prepared by using two different procedures to homogenize the film forming dispersions (rotor-stator and rotor-stator plus microfluidizer). The influence of both HPMC-starch ratio and the homogenization method on the structural, optical, tensile and barrier properties of the films was analysed. The ageing of the films was also studied by characterizing them after 5 weeks' storage. Starch re-crystallization in newly prepared and stored films was analysed by means of X-ray diffraction. HPMC-corn starch films showed phase separation of polymers, which was enhanced when microfluidization was applied to the film forming dispersion. Nevertheless, HPMC addition inhibited starch re-crystallization during storage, giving rise to more flexible films at the end of the period. Water barrier properties of starch films were hardly affected by the addition of HPMC, although oxygen permeability increased due to its poorer oxygen barrier properties.

  5. Influence of alloying elements on structure and some physical properties of quenched Sn-Sb alloy

    NASA Astrophysics Data System (ADS)

    Kamal, M.; El-Bediwi, A. B.; El-Shobaki, M. R.

    2006-09-01

    We study the influence of ternary and quaternary alloying elements (Pb, Cd, Cu or Cu-Pb and Cu-Cd) on structural, electrical, hardness and other mechanical properties of Sn-Sb alloys (using an X-ray diffractometer and optical microscope, the double bridge method, Vickers hardness tester and the dynamic resonance method) to produce the best alloy for bearing applications. Adding Cu or Pb to Sn-Sb alloys improves their bearing properties, such as the mechanical properties (elastic modulus, internal friction, hardness and fracture strain) and thermal conductivity. Also, adding Cu, Pb or Cu-Pb to Sn-Sb alloys makes them excellent in their bearing applications and environmental hazards when compared with the Pb88Sn10Cu2 alloy for automotive applications (FIAT Normalizzazione) and the lead-based Babbitt bearing alloy.

  6. Influence of molybdenum on the creep properties of nickel-base superalloy single crystals

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Nathal, M. V.; Pearson, D. D.

    1990-01-01

    The Mo content of an alloy series based on Ni-6 wt pct Al-6 wt pct Ta was systematically varied from 9.8 to 14.6 wt pct, in order to ascertain the influence of Mo on the creep properties of single crystals. The optimum initial gamma-gamma prime microstructure for raft development and creep strength was established in each alloy before testing. It was found that, as the Mo content increased from 9.8 to 14.0 percent, the magnitude of the lattice mismatch increased; upon reaching 14.6 percent, a degradation of mechanical properties occurred due to the precipitation of a third phase. These results suggest that small refractory metal content and initial gamma-prime variations can profoundly affect mechanical properties.

  7. Influence of nanomorphology on the melting and catalytic properties of convex polyhedral nanoparticles

    NASA Astrophysics Data System (ADS)

    Guisbiers, G.; Abudukelimu, G.

    2013-02-01

    It is well known today that the melting temperature and the catalytic activation energy of nanoparticles are size-dependent. These properties are here analyzed in a size range between 4 and 100 nm, with a special attention to sizes below 20 nm. Nevertheless, their unique properties are determined not only by their size but also by their shape defined by the relative area of different surface facets. In this paper, the influence of crystal structure and shape of the nanoparticles on the melting and catalytic properties are theoretically investigated. The theory is developed for cubic crystal structures i.e., simple cubic, body centered cubic, and face centered cubic. The following shapes are then considered: tetrahedron, cube, octahedron, decahedron, dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron, and icosahedron. The predictions were compared with available experimental data and molecular dynamics simulation results coming from the literature and relatively good agreement was obtained for gold, silver, nickel, and platinum nanoparticles.

  8. Influence of structural defects on the optical properties of strongly coupled Au nanoshell arrays

    NASA Astrophysics Data System (ADS)

    Zhou, Xin; Fang, JianShu; Liao, XiangPing; Zhu, QianQuan; Liu, ZhiMin; Tang, Bin

    2013-09-01

    The effects of different defects on optical properties and plasmon resonances properties of Au nanoshell arrays were investigated by using the finite-difference time-domain (FDTD) theory. It is found that the optical properties of the nanoshell arrays are strongly influenced by different defects. We show that when the hollow Au nanoshell arrays are placed in air, there is a wide photonic band gap (PBG) in the infrared region, but the band gap becomes narrower as we introduced different defects. Based on the distributions of electric field component E z and the total energy distribution of the electric and the magnetic field, we show that there exhibit dipoles field distributions for the plasmon mode at the long-wavelength edge of the band gap, but composite higher order modes are excited at the short-wavelength edge of the band gap. The plasmon resonant modes also can be controlled by introducing defects.

  9. Magnetic properties of bcc Iron surfaces and the influence of the chemical environment: electronic structure calculations.

    PubMed

    Fischer, Guntram; Gerber, Iann C

    2015-01-14

    We have investigated the magnetic properties of low-indexed iron surfaces and the influence of the chemical environment on these properties. We have considered the (1 0 0), (1 1 0), (1 1 1), (2 1 1) and (3 1 0) surfaces, both, bare and with the presence of adsorbates. These were chosen to mimic realistic chemical synthesis environments, being H, Cl, HCl, NH3, NH4Cl, or CH3COOH. We have found an increased magnetization at all bare surfaces. Upon H adsorption the magnetization is generally reduced, but still above the bulk value. All other ligands and their dissociated parts alter the magnetic properties of the surfaces only weakly. Our calculations do not indicate that ligands are responsible for experimental observations of Fe nanoparticles with average magnetizations below the bulk value.

  10. Magnetic properties of bcc Iron surfaces and the influence of the chemical environment: electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Fischer, Guntram; Gerber, Iann C.

    2015-01-01

    We have investigated the magnetic properties of low-indexed iron surfaces and the influence of the chemical environment on these properties. We have considered the (1 0 0), (1 1 0), (1 1 1), (2 1 1) and (3 1 0) surfaces, both, bare and with the presence of adsorbates. These were chosen to mimic realistic chemical synthesis environments, being H, Cl, HCl, NH3, NH4Cl, or CH3COOH. We have found an increased magnetization at all bare surfaces. Upon H adsorption the magnetization is generally reduced, but still above the bulk value. All other ligands and their dissociated parts alter the magnetic properties of the surfaces only weakly. Our calculations do not indicate that ligands are responsible for experimental observations of Fe nanoparticles with average magnetizations below the bulk value.

  11. Influence of calcium compounds on the mechanical properties of fly ash geopolymer pastes.

    PubMed

    Temuujin, J; van Riessen, A; Williams, R

    2009-08-15

    The influence of calcium compounds (CaO and Ca(OH)(2)) on the mechanical properties of fly ash based geopolymers has been studied. Calcium compounds were substituted in fly ash at 1, 2 and 3 wt%, respectively. Curing of the geopolymers was performed at ambient temperature (20 degrees C) and 70 degrees C. Addition of calcium compounds as a fly ash substitute improved mechanical properties for the ambient temperature cured samples while decreasing properties for the 70 degrees C cured samples. Seven days compressive strength of the ambient temperature cured samples increased from 11.8 (2.9) to 22.8 (3.8)MPa and 29.2 (1.1)MPa for 3% CaO and 3% Ca(OH)(2) additions, respectively.

  12. Influence of Weld Cooling Rate on Microstructure and Mechanical Properties of Alloy 718 Weldments

    NASA Astrophysics Data System (ADS)

    Sivaprasad, K.; Ganesh Sundara Raman, S.

    2008-09-01

    Even though alloy 718 is the best for welding among all nickel-base superalloys, the formation of the Laves phase in welds is a major concern. The presence of this phase drastically degrades mechanical properties of the welds. To study the influence of weld cooling rate on microstructure and mechanical properties of alloy 718 weldments, two distinct welding processes were adopted—gas tungsten arc (GTA) and electron beam (EB) welding. The EB welding resulted in finer and relatively discrete Laves phase in lower quantity due to higher cooling rates prevailing in this process. On the other hand, due to lower cooling rates, GTA weld fusion zones exhibited coarse Laves with higher niobium. Depletion of the primary strengthening element niobium in the surrounding regions of Laves promoted crack propagation. Because EB welds had finer and lower amount of Laves, EB weldments exhibited superior mechanical properties compared with GTA weldments.

  13. The influence of tilt grain boundaries on the mechanical properties of bicrystalline graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Xu, Na; Guo, Jian-Gang; Cui, Zhen

    2016-10-01

    The mechanical properties of bicrystalline graphene nanoribbons with various tilt grain boundaries (GBs) which typically consist of repeating pentagon-heptagon ring defects are investigated based on the method of molecular structural mechanics. The GB models are constructed via the theory of disclinations in crystals, and the elastic properties and ultimate strength of bicrystalline graphene nanoribbons are calculated under uniaxial tensile loads in perpendicular and parallel directions to grain boundaries. The dependence of mechanical properties is analyzed on the chirality and misorientation angles of graphene nanoribbons, and the experimental phenomena that Young's modulus and ultimate strength of bicrystalline graphene nanoribbons can either increase or decrease with the grain boundary angles are further verified and discussed. In addition, the influence of GB on the size effects of graphene Young's modulus is also analyzed.

  14. Continuous melt granulation: Influence of process and formulation parameters upon granule and tablet properties.

    PubMed

    Monteyne, Tinne; Vancoillie, Jochem; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-01

    The pharmaceutical industry has a growing interest in alternative manufacturing models allowing automation and continuous production in order to improve process efficiency and reduce costs. Implementing a switch from batch to continuous processing requires fundamental process understanding and the implementation of quality-by-design (QbD) principles. The aim of this study was to examine the relationship between formulation-parameters (type binder, binder concentration, drug-binder miscibility), process-parameters (screw speed, powder feed rate and granulation temperature), granule properties (size, size distribution, shape, friability, true density, flowability) and tablet properties (tensile strength, friability, dissolution rate) of four different drug-binder formulations using Design of experiments (DOE). Two binders (polyethylene glycol (PEG) and Soluplus®) with a different solid state, semi-crystalline vs amorphous respectively, were combined with two model-drugs, metoprolol tartrate (MPT) and caffeine anhydrous (CAF), both having a contrasting miscibility with the binders. This research revealed that the granule properties of miscible drug-binder systems depended on the powder feed rate and barrel filling degree of the granulator whereas the granule properties of immiscible systems were mainly influenced by binder concentration. Using an amorphous binder, the tablet tensile strength depended on the granule size. In contrast, granule friability was more important for tablet quality using a brittle binder. However, this was not the case for caffeine-containing blends, since these phenomena were dominated by the enhanced compression properties of caffeine Form I, which was formed during granulation. Hence, it is important to gain knowledge about formulation behavior during processing since this influences the effect of process parameters onto the granule and tablet properties.

  15. Diffuse Hepatic Calcifications in a Transfusion-Dependent Patient with Beta-Thalassemia: A Case Report

    PubMed Central

    Saki, Forough; Bordbar, Mohammad Reza; Imanieh, Mohammad Hadi; Karimi, Mehran

    2013-01-01

    Hepatic calcification is usually associated with infectious, vascular, or neoplastic processes in the liver. We report the first case of beta-thalassemia major with isolated diffuse hepatic calcification in a 23 year old woman, who had been transfusion-dependent since the age of 6 months. She was referred to our center with a chief complaint of abdominal pain. Computed tomography scan of the abdomen revealed diffuse hepatic calcification in the right, left, and caudate lobes of the liver. Her medical history disclosed hypoparathyroidism as well as chronic hepatitis C virus infection, which was successfully treated but led to early micronodular cirrhosis on liver biopsy. Other studies done to search for the cause of hepatic calcification failed to reveal any abnormalities. We suspect that hypoparathyroidism caused liver calcification, and should be, therefore, considered in the differential diagnosis of hepatic calcification if other causative factors have been ruled out. PMID:24174700

  16. Elucidating the Molecular-Level Events in Valvular Interstitial Cell Calcification to Improve the Design of Tissue-Engineered Heart Valves

    NASA Astrophysics Data System (ADS)

    Gu, Xiaoxiao

    Calcification is the leading cause of native and bioprosthetic heart valve failure, yet its etiology and progression remain poorly understood. Total valve replacement, which is both invasive and accompanied by numerous shortcomings, is commonly performed to replace stenotic valves, but there are currently no medical agents that are FDA-approved for the prevention of aortic valve disease progression. Tissue engineering offers an attractive alternative to current valve replacement options. Thus, there is a pressing need to: (1) better understand the progression of valve calcification, (2) develop more options for prevention and treatment of valve calcification, and (3) define the properties of appropriate scaffold environments that will support the growth of engineered valve tissue. In this thesis, we describe our plan to bring together these goals in cardiovascular medicine: we aim to identify differences between calcifying and non-calcifying valve cultures and then use this information to discover potential calcification inhibitors and define biomaterial environments that can be used to support either healthy or diseased valvular interstitial cell function.

  17. Hydrologic influences on soil properties along ephemeral rivers in the Namib Desert

    USGS Publications Warehouse

    Jacobson, P.J.; Jacobson, K.M.; Angermeier, P.L.; Cherry, D.S.

    2000-01-01

    Soils were examined along three ephemeral rivers in the Namib Desert to assess the influence of their hydrologic characteristics on soil properties. Soils consisted of layers of fluvially deposited, organic-rich silts, interstratified with fluvial and aeolian sands. The most significant influence of the ephemeral hydrologic regime upon soils was related to the downstream alluviation associated with hydrologic decay. This alluviation increased the silt proportion of soils in the lower reaches of the rivers. Organic carbon, nitrogen and phosphorous were correlated with silt content, and silt deposition patterns influenced patterns of moisture availability and plant rooting, creating and maintaining micro-habitats for various organisms. Localized salinization occurred in association with wetland sites and soluble salt content tended to increase downstream. Because of the covariance between silt and macronutrients, and the influence of silt upon moisture availability and habitat suitability, alluviation patterns associated with the hydrologic regime strongly influence the structure, productivity, and spatial distribution of biotic communities in ephemeral river ecosystems. (C) 2000 Academic Press.

  18. Calcification of coccolithophores in diverse chemical oceanic settings

    NASA Astrophysics Data System (ADS)

    Beaufort, L.; Ruiz-Pino, D.; Metzl, N.; Goyet, C.

    2008-12-01

    The constant release of carbon in the atmosphere from human activity induces ocean acidification, with potential threat for calcifying organisms such as coccolithophores. The effect of acidification on Coccolithophores is not yet clearly understood: Culture experiments appears to show complex results and may induce opposite conclusions on the calcification response of the algae to an increase of pCO2 at the species level (for E. huxleyi compare Riebesell (2000) and Iglesias-Rodriguez et al. (2008)) or depending of the species (Langer et al., 2006). Natural oceanic environment offers an excellent laboratory to test the response of coccolithophores to various chemical settings. It is for example possible to sample a large spectrum of alkalinity or of carbonate saturation state conditions in the present surface ocean. Here we present estimation of the degree of calcification of important coccolithophore taxa in 170 water samples collected in diverse oceanic settings (Patagonian Shelf, Southern Indian Ocean, and Tropical Pacific Ocean). In this water collection, temperature, alkalinity, and pH ranged from 3 to 31° C, 2108 to 2418 μmole kg-1 and 7.6 to 8.2 respectively. The calcite weight of the coccoliths and of the coccospheres of Gephyrocapsa sp and of Emiliania huxleyi was estimated using automated pattern recognition and automated morphometry software. The results indicate that the degree of calcification of these species strongly depends on alkalinity, temperature and calcite saturation state. In area of high alkalinity, high temperature, and high calcite saturation state, these coccolithophores secrete the heaviest coccospheres and coccoliths. The facts that in the Chilean upwelling, where pH was the lowest, the mean coccolith weights are in the average of the global distribution and that the mean lightest and mean heaviest coccoliths are found both at higher pH, indicate that the effect of pH on its studied range is not a critical parameter that can be studied

  19. Effect of image quality on calcification detection in digital mammography

    PubMed Central

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-01-01

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  20. Effect of image quality on calcification detection in digital mammography

    SciTech Connect

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-06-15

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  1. Age-related incidence of pineal calcification detected by computed tomography

    SciTech Connect

    Zimmerman, R.A.; Bilaniuk, L.T.

    1982-03-01

    The age-related incidence of detectable pineal calcification in 725 patients (age range, newborn-20 yrs) suggests that there is a relationship between calcification and the hormonal role played by the pineal gland in the regulation of sexual development. Pineal calcification (demonstrated by computed tomography (CT) on 8-mm-thick sections) in patients less than 6 years old should be looked upon with suspicion, and follow-up CT should be considered to exclude the possible development of a pineal neoplasm.

  2. Metal matrix composite micromechanics: In-situ behavior influence on composite properties

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1989-01-01

    Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the current material model describes a time-temperature-stress dependency of the constituent properties in a material behavior space. The composite properties are synthesized from the constituent instantaneous properties by virtue of composite micromechanics and macromechanics models. The behavior of metal matrix composites depends on fabrication process variables, in situ fiber and matrix properties, bonding between the fiber and matrix, and/or the properties of an interphase between the fiber and matrix. Specifically, the influence of in situ matrix strength and the interphase degradation on the unidirectional composite stress-strain behavior is examined. These types of studies provide insight into micromechanical behavior that may be helpful in resolving discrepancies between experimentally observed composite behavior and predicted response.

  3. Influence of Halide Solutions on Collagen Networks: Measurements of Physical Properties by Atomic Force Microscopy

    PubMed Central

    Kempe, André; Lackner, Maximilian

    2016-01-01

    The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients. PMID:27721994

  4. Influence of Thermal and Radiation Effects on Microstructural and Mechanical Properties of Nb-1Zr

    SciTech Connect

    Leonard, Keith J; Busby, Jeremy T; Zinkle, Steven J

    2011-01-01

    Refractory metals and alloys offer attractive high-temperature properties, most of which are suitable for applications in nuclear environments including high temperature strength, good thermal conductivity, and compatibility with most liquid metal coolants. One of only two commercially produced Nb-alloys, Nb-1Zr has long been considered for various compact reactor designs. Nb-1Zr has also recently been considered for high-performance Gen IV gas reactor concepts. However, there are significant gaps in the irradiated materials database, especially at temperatures above 800 K. Recent work has shown that irradiated properties of Nb-1Zr are strongly controlled by phase-related transformations in the microstructure. Changes in the microstructure (obtained via scanning and transmission electron microscopy) and corresponding mechanical properties of Nb-1Zr were examined following fission reactor irradiation experiments at temperatures of 1073, 1223 and 1373 K to 1.9 dpa (displacements per atom) and compared with material thermally aged for similar exposure times of ~1100 h. Thermally driven changes in the development of precipitate phases showed a greater influence on mechanical properties compared to irradiation-induced defects for these irradiation conditions. The changes in material density, electrical resistivity and mechanical properties of the irradiated and thermally aged materials in association with microstructural developments are discussed.

  5. The influence of large deformations on mechanical properties of sinusoidal ligament structures

    NASA Astrophysics Data System (ADS)

    Strek, Tomasz; Jopek, Hubert; Wojciechowski, Krzysztof W.

    2016-05-01

    Studies of mechanical properties of materials, both theoretical and experimental, usually deal with linear characteristics assuming a small range of deformations. In particular, not much research has been published devoted to large deformations of auxetic structures - i.e. structures exhibiting negative Poisson’s ratio. This paper is focused on mechanical properties of selected structures that are subject to large deformations. Four examples of structure built of sinusoidal ligaments are studied and for each geometry the impact of deformation size and geometrical parameters on the effective mechanical properties of these structures are investigated. It is shown that some of them are auxetic when compressed and non-auxetic when stretched. Geometrical parameters describing sinusoidal shape of ligaments strongly affect effective mechanical properties of the structure. In some cases of deformation, the increase of the value of amplitude of the sinusoidal shape decreases the effective Poisson’s ratio by 0.7. Therefore the influence of geometry, as well as the arrangement of ligaments allows for smart control of mechanical properties of the sinusoidal ligament structure being considered. Given the large deformation of the structure, both a linear elastic material model, and a hyperelastic Neo-Hookean material model are used.

  6. The influence of hydrogen bonding on the physical properties of ionic liquids.

    PubMed

    Fumino, Koichi; Peppel, Tim; Geppert-Rybczyńska, Monika; Zaitsau, Dzmitry H; Lehmann, Jochen K; Verevkin, Sergey P; Köckerling, Martin; Ludwig, Ralf

    2011-08-21

    Potential applications of ionic liquids depend on the properties of this class of liquid material. To a large extent the structure and properties of these Coulomb systems are determined by the intermolecular interactions among anions and cations. In particular the subtle balance between Coulomb forces, hydrogen bonds and dispersion forces is of great importance for the understanding of ionic liquids. The purpose of the present paper is to answer three questions: Do hydrogen bonds exist in these Coulomb fluids? To what extent do hydrogen bonds contribute to the overall interaction between anions and cations? And finally, are hydrogen bonds important for the physical properties of ionic liquids? All these questions are addressed by using a suitable combination of experimental and theoretical methods including newly synthesized imidazolium-based ionic liquids, far infrared spectroscopy, terahertz spectroscopy, DFT calculations, differential scanning calorimetry (DSC), viscometry and quartz-crystal-microbalance measurements. The key statement is that although ionic liquids consist solely of anions and cations and Coulomb forces are the dominating interaction, local and directional interaction such as hydrogen bonding has significant influence on the structure and properties of ionic liquids. This is demonstrated for the case of melting points, viscosities and enthalpies of vaporization. As a consequence, a variety of important properties can be tuned towards a larger working temperature range, finally expanding the range of potential applications.

  7. Harnessing osteopontin and other natural inhibitors to mitigate ectopic calcification of bioprosthetic heart valve material

    NASA Astrophysics Data System (ADS)

    Ohri, Rachit

    Dystrophic calcification has been the long-standing major cause of bioprosthetic heart valve failure, and has been well studied in terms of the underlying causative mechanisms. Such understanding has yielded several anti-calcification strategies involving biomaterial modification at the preparation stage: chemical alteration, extraction of calcifiable components, or material modification with small-molecule anti-calcific agents. However, newer therapeutic opportunities are offered by the growing illustration of the pathology as a dynamic, actively regulated process involving several gene products, such as osteopontin (OPN), matrix-gla protein (MGP) and glycosaminoglycans (GAGs). Osteopontin, a multi-functional matricellular glycosylated phosphoprotein has emerged as a prime candidate for the role of an in vivo inhibitor of ectopic calcification with two putative mechanisms: crystal poisoning and mineral-dissolution. The full therapeutic realization of its potential necessitates a better understanding of the mechanisms of anti-calcification by osteopontin, as well as appropriate in vivo models in which to evaluate its efficacy, potency and molecular mechanisms. In this work, we pursued the development and characterization of a reliable in vivo model with the OPN-null mouse to simulate the calcification of bioprosthetic valve material, namely glutaraldehyde-fixed bovine pericardium (GFBP) tissue. Subsequently, we used the calcification model to evaluate hypotheses based on the anti-calcific potential of osteopontin. Several modes of administering exogenous OPN to the implant site in OPN-null mice were explored, including soluble injected OPN, OPN covalently immobilized on the biomaterial, and OPN adsorbed onto the biomaterial. An investigation of the structure-function aspects of the anti-calcific ability of OPN was also pursued in the in vivo model. The OPN-null mouse was also used as an in vivo test-bed to evaluate the anti-calcific potential of other biomolecules

  8. [Multidetector row CT in assessment of coronary artery calcification on hemodialisis].

    PubMed

    Caro, P; Delgado, R; Dapena, F; Núñez, A

    2007-01-01

    Vascular calcification is a strong predictor of cardiovascular and all-cause mortality. Coronary artery calcification is more frequent, more extensive and progresses more rapidly in CKD than in general population. They are also considered a marker of coronary heart disease, with high prevalence and functional significance. It suggests that detection and surveillance may be worthwhile in general clinical practice. New non-invasive image techniques, like Multi-detector row CT, a type of spiral scanner, assess density and volume of calcification at multiple sites and allow quantitative scoring of vascular calcification using calcium scores analogous to those from electron-beam CT. We have assessed and quantified coronary artery calcification with 16 multidetector row CT in 44 patients on hemodialysis and their relationship with several cardiovascular risk factors. Coronary artery calcification prevalence was of 84 % with mean calcium score of 1580 +/- 2010 ( r 0-9844) with calcium score > 400 in 66% of patients. It was usually multiple, affecting more than two vessels in more than 50%. In all but one patient, left anterior descending artery was involved with higher calcium score level at right coronary artery. Advanced age, male, diabetes, smoking, more morbidity, cerebrovascular disease previous, and calcium-binders phosphate and analogous vitamin D treatment would seem to be associated with coronary artery calcification. Coronary artery calcification is very frequent and extensive, usually multiple and associated to modifiable risk factors in hemodialysis patients. Multi-detector-row CT seems an effective, suitable, readily applicable method to assess and quantify coronary artery calcification.

  9. Computed Tomographic Pattern of Physiological Intracranial Calcifications in a City in Central Africa

    PubMed Central

    Uduma, Uduma Felix; Pius, Fokam; Mathieu, Motah

    2012-01-01

    Objective: Intracranial calcifications underlie certain brain diseases which may be de novo or systemic. But calclfications un-connected to pathologies are classified physiological. Aim: To evaluate physiological intracranial calcifications in Douala with establishment of earliest age range of detection. Materials and Methods: Prospective study of brain computed tomograms was done from April to October 2009 using Schumadzu CT Scan machine. Axial, reconstructed and bone window images as well Hounsfield unit measurements were used for final evaluations. Results were analysed with SSPS 3. Results: 132 patients with 75 males and 57 females were studied and 163 separate calcifications were identified due to co-existent calcifications. The highest calcification was in choroid plexi, constituiting 56.82% of the studied population. This was followed by pineal gland. Both were commonly co-existent with advancing age. These calcifications were first seen at 10-19years. No type of physiological intracranial calcification was seen below age 10. The least calcification of 0.76% of population was in dentate nucleus. Conclusion: No intra-cranial physiological calcifications started earlier than 9years in Douala, a city in Cameroon, Central Africa. PMID:22980109

  10. Influence of color on dielectric properties of marinated poultry breast meat.

    PubMed

    Samuel, D; Trabelsi, S

    2012-08-01

    The dielectric behavior of foods when exposed to radio-frequency and microwave electric fields is highly influenced by moisture content and the degree of water binding with constituents of the food materials. The ability to correlate specific food quality characteristics with the dielectric properties can lead to the development of rapid, nondestructive techniques for such quality measurements. Water-holding capacity is a critical attribute in meat quality. Up to 50% of raw poultry meat in the United States is marinated with mixtures of water, salts, and phosphates. The objective of this study was to determine if variations in breast meat color would affect the dielectric properties of marinated poultry meat over a broad frequency range from 500 MHz to 50 GHz. Poultry meat was obtained from a local commercial plant in Georgia (USA). Color and pH measurements were taken on the breast filets. Groups of breast filets were sorted into classes of pale and normal before adding marination pickup percentages of 0, 5, 10, and 15. Breast filets were vacuum-tumbled and weighed for pickup percentages. Dielectric properties of the filets were measured with a coaxial open-ended probe on samples equilibrated to 25°C. Samples from pale meat exhibited higher dielectric properties than samples from normal meat. No differences could be observed between samples from pale and normal meat after marination of the samples. Overall, dielectric properties increased as the marination pickup increased (α=0.05). Marination pickup strongly influenced the dielectric loss factor. Differences between samples marinated at different pickup levels were more pronounced at lower frequencies for the dielectric loss factor. As frequency increased, the differences between samples decreased. Differences in dielectric constant between samples were not as consistent as those seen with the dielectric loss factor.

  11. Needle-like ion-doped hydroxyapatite crystals influence osteogenic properties of PCL composite scaffolds.

    PubMed

    Guarino, V; Veronesi, F; Marrese, M; Giavaresi, G; Ronca, A; Sandri, M; Tampieri, A; Fini, M; Ambrosio, Luigi

    2016-02-29

    Surface topography and chemistry both play a crucial role on influencing cell response in 3D porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties-in the bulk and along pore surface-promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(Ɛ-caprolactone) (PCL) can be augmented by the peculiar properties of Mg(2+) ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals also influences microscopic (i.e. crystallinity, adhesion forces) and macroscopic (i.e. roughness) properties with relevant effects on biological response of the composite scaffold: differential scanning calorimetry (DSC) analyses clearly indicate a reduction of crystallization heat-from 66.75 to 43.05 J g(-1)-while atomic force microscopy (AFM) ones show a significant increase of roughness-from (78.15  ±  32.71) to (136.13  ±  63.21) nm-and of pull-off forces-from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of alkaline phosphatase (ALP) and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration.

  12. Influence of processing sequence on the tribological properties of VGCF-X/PA6/SEBS composites

    NASA Astrophysics Data System (ADS)

    Osada, Yu; Nishitani, Yosuke; Kitano, Takeshi

    2016-03-01

    In order to develop the new tribomaterials for mechanical sliding parts with sufficient balance of mechanical and tribological properties, we investigated the influence of processing sequence on the tribological properties of the ternary nanocomposites: the polymer blends of polyamide 6 (PA6) and styrene-ethylene/butylene-styrene copolymer (SEBS) filled with vapor grown carbon fiber (VGCF-X), which is one of carbon nanofiber (CNF) and has 15nm diameter and 3μm length. Five different processing sequences: (1) VGCF-X, PA6 and SEBS were mixed simultaneously (Process A), (2) Re-mixing (Second compounding) of the materials prepared by Process A (Process AR),(3) SEBS was blended with PA6 (PA6/SEBS blends) and then these blends were mixed with VGCF-X (Process B), (4) VGCF-X was mixed with PA6 (VGCF-X/PA6 composites) and then these composites were blended with SEBS (Process C), and (5) VGCF-X were mixed with SEBS (VGCF-X/SEBS composites) and then these composites were blended with PA6 (Process D) were attempted for preparing of the ternary nanocomposites (VGCF-X/PA6/SEBS composites). These ternary polymer nanocomposites were extruded by a twin screw extruder and injection-molded. Their tribological properties were evaluated by using a ring-on-plate type sliding wear tester under dry condition. The tribological properties such as the frictional coefficient and the specific wear rate were influenced by the processing sequence. These results may be attributed to the change of internal structure formation, which is a dispersibility of SEBS particle and VGCF-X in ternary nanocomposites (VGCF-X/PA6/SEBS) by different processing sequences. In particular, the processing sequences of AR, B and D, which are those of re-mixing of VGCF-X, have a good dispersibility of VGCF-X for the improvement of tribological properties.

  13. Influence of different crosslinking treatments on the physical properties of collagen membranes.

    PubMed

    Charulatha, V; Rajaram, A

    2003-02-01

    The physical properties of collagen-based biomaterials are profoundly influenced by the method and extent of crosslinking. In this study, the influence of various crosslinking treatments on the physical properties of reconstituted collagen membranes was assessed. Five crosslinking agents viz., GTA, DMS, DTBP, a combination of DMS and GTA and acyl azide method were used to stabilize collagen matrices. Crosslinking density, swelling ratio, thermo-mechanical properties, stress-strain characteristics and resistance to collagenase digestion were determined to evaluate the physical properties of crosslinked matrices. GTA treatment induced the maximum number of crosslinks (13) while DMS treatment induced the minimum (7). Of the two diimidoesters (DMS and DTBP), DTBP was a more effective crosslinking agent due to the presence of disulphide bonds in the DTBP crosslinks. T(s) for DTBP and DMS crosslinked collagen were 80 degrees C and 70 degrees C, and their HIT values were 5.4 and 2.85MN/m(2), respectively. Low concentration of GTA (0.01%) increased the crosslinking density of an already crosslinked matrix (DMS treated matrix) from 7 to 12. Lowest fracture energy was observed for the acyl azide treated matrix (0.61MJ/m(3)) while the highest was observed for the GTA treated matrix (1.97MJ/m(3)). The tensile strength of GTA treated matrix was maximum (12.4MPa) and that of acyl azide treated matrix was minimum (7.2MPa). GTA, DTBP and acyl azide treated matrices were equally resistant to collagenase degradation with approximately 6% solubilization after 5h while the DMS treated was least stable with 52.4% solubilization after the same time period. The spatial orientation of amino acid side chain residues on collagen plays an important role in determining the crosslinking density and consequent physical properties of the collagen matrix.

  14. Using 137 Cs measurements to investigate the influence of erosion and soil redistribution on soil properties.

    PubMed

    Du, P; Walling, D E

    2011-05-01

    Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to investigate using traditional approaches to documenting soil redistribution rates involving erosion plots and predictive models. However, the use of the fallout radionuclide (137)Cs to document medium-term soil redistribution rates offers a means of overcoming many of the limitations associated with traditional approaches. The study reported sought to demonstrate the potential for using (137)Cs measurements to assess the influence of soil erosion and redistribution on soil properties (particle size composition, total C, macronutrients N, P, K and Mg, micronutrients Mn, Mo, Fe, Cu and Zn and other elements, including Ti and As). (137)Cs measurements undertaken on 52 soil cores collected within a 7 ha cultivated field located near Colebrooke in Devon, UK were used to establish the magnitude and spatial pattern of medium-term soil redistribution rates within the field. The soil redistribution rates documented for the individual sampling points within the field ranged from an erosion rate of -12.9 t ha(-1) yr(-1) to a deposition rate of 19.2 t ha(-1) yr(-1). Composite samples of surface soil (0-5 cm) were collected immediately adjacent to each coring point and these samples were analysed for a range of soil properties. Individual soil properties associated with these samples showed significant variability, with CV values generally lying in the range 10-30%. The relationships between the surface soil properties and the soil redistribution rate were analysed. This analysis demonstrated statistically significant relationships between some soil properties (total phosphorus, % clay, Ti and As) and the soil redistribution rate, but for

  15. Influence of internal temperature development during manufacturing on thick laminates compression fatigue properties

    NASA Astrophysics Data System (ADS)

    Lahuerta, F.; Nijssen, RPL

    2016-07-01

    Thick laminates (above 6 mm) are increasingly present in large composite structures such as wind turbine blades. Blade designs are based on static and fatigue coupon tests on 14mm thick laminates. However, a thickness effect has been observed, showing significantly shorter fatigue life in thick laminates. Different factors are suspected to be involved in the decreased static and dynamic performance of thick laminates. These include the effect of selfheating during fatigue testing, scaling effects, and the influence of residual stresses due to temperature gradients during manufacturing. This work studies the influence of the temperature gradients during resin infusion on the through-thickness fatigue properties in thick laminates. Coupons from thick laminates cured at different curing rates have been tested in fatigue. The work reports the compression fatigue properties of a thick laminate and relates the results with the curing rate. Safety factors between 1.23 and 1.60 regarding the influence of the curing cycles in thick laminates are reported.

  16. Copper dynamics under alternating redox conditions is influenced by soil properties and contamination source.

    PubMed

    Balint, Ramona; Said-Pullicino, Daniel; Ajmone-Marsan, Franco

    2015-02-01

    Understanding the effect of soil redox conditions on contaminant dynamics is of significant importance for evaluating their lability, mobility and potential transfer to other environmental compartments. Under changing redox conditions, soil properties and constituents such as Fe and Mn (hydr)oxides and organic matter (OM) may influence the behavior of associated metallic elements (MEs). In this work, the redox-driven release and redistribution of Cu between different soil pools was studied in three soils having different contamination sources. This was achieved by subjecting soil columns to a series of alternating reducing and oxidizing cycles under non-limiting C conditions, and assessing their influence on soil pore water, leachate and solid phase composition. Results showed that, in all soils, alternating redox conditions led to an increase in the distribution of Cu in the more labile fractions, consequently enhancing its susceptibility to loss. This was generally linked to the redox-driven cycling of Fe, Mn and dissolved organic matter (DOM). In fact, results suggested that the reductive dissolution of Fe and Mn (hydr)oxides and subsequent reprecipitation as poorly-ordered phases under oxic conditions contributed to the release and mobilization of Cu and/or Cu-containing organometallic complexes. However, the behavior of Cu, as well as the mechanisms controlling Cu release and loss with redox cycling, was influenced by both soil properties (e.g. pH, contents of easily reducible Fe and Mn (hydr)oxides) and source of Cu contamination.

  17. Short Term Preservation of Hide Using Vacuum: Influence on Properties of Hide and of Processed Leather

    PubMed Central

    Gudro, Ilze; Valeika, Virgilijus; Sirvaitytė, Justa

    2014-01-01

    The objective of this work was to investigate vacuum influence on hide preservation time and how it affects hide structure. It was established that vacuum prolongs the storage time without hide tissue putrefaction up to 21 days when the storage temperature is 4°C. The microorganisms act for all storage times, but the action is weak and has no observable influence on the quality of hide during the time period mentioned. The hide shrinkage temperature decrease is negligible, which shows that breaking of intermolecular bonds does not occur. Optical microscopy, infrared spectroscopy and differential scanning calorimetry also did not show any structural changes which can influence the quality of leather produced from such hide. The qualitative indexes of wet blue processed under laboratory conditions and of leather produced during industrial trials are presented. Indexes such as chromium compounds exhaustion, content of chromium in leather, content of soluble matter in dichloromethane, strength properties, and shrinkage temperature were determined. Properties of the leather produced from vacuumed hide under industrial conditions conformed to the requirements of shoe upper leather. PMID:25393637

  18. The fabric of thought: priming tactile properties during reading influences direct tactile perception.

    PubMed

    Brunyé, Tad T; Walters, Eliza K; Ditman, Tali; Gagnon, Stephanie A; Mahoney, Caroline R; Taylor, Holly A

    2012-01-01

    The present studies examined whether implied tactile properties during language comprehension influence subsequent direct tactile perception, and the specificity of any such effects. Participants read sentences that implicitly conveyed information regarding tactile properties (e.g., Grace tried on a pair of thick corduroy pants while shopping) that were either related or unrelated to fabrics and varied in implied texture (smooth, medium, rough). After reading each sentence, participants then performed an unrelated rating task during which they felt and rated the texture of a presented fabric. Results demonstrated that the texture properties implied in sentences influence direct tactile perception. Specifically, after reading about a smooth or rough texture, subsequent fabric ratings became notably smoother or rougher, respectively. However, we also show that there was some specificity to these effects: Fabric-related sentences elicited more specific and interactive effects on subsequent ratings. Together, we demonstrate that under certain circumstances, language comprehension can prime tactile representations and affect direct tactile perception. Results are discussed with regard to the nature and scope of multimodal mental simulation during reading.

  19. Influences of the steam sterilization on the properties of calcium phosphate porous bioceramics.

    PubMed

    Li, Xiangfeng; Guo, Bo; Xiao, Yumei; Yuan, Tun; Fan, Yujiang; Zhang, Xingdong

    2016-01-01

    The influences of steam sterilization on the physicochemical properties of calcium phosphate (Ca-P) porous bioceramics, including β-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP) and hydroxyapatite (HA) are investigated. After being steam sterilized in an autoclave (121 °C for 40 min), the porous bioceramics are dried and characterized. The steam sterilization has no obvious effects on the phase composition, thermal stability, pH value and dissolubility of β-TCP porous bioceramic, but changes its morphology and mechanical strength. Meanwhile, the steam sterilization leads to the significant changes of the morphology, phase composition, pH value and dissolubility of BCP porous bioceramic. The increase of dissolubility and mechanical strength, the decrease of pH value of the immersed solution and partial oriented growth of crystals are also observed in HA porous bioceramic after steam sterilization. These results indicate that the steam sterilization can result in different influences on the physicochemical properties of β-TCP, BCP and HA porous bioceramics, thus the application of the steam sterilization on the three kinds of Ca-P porous bioceramics should be considered carefully based on the above changed properties.

  20. Influence of Morphology on Electrical Properties of Syndiotactic Polypropylene Compared with Those of Isotactic Polypropylene

    NASA Astrophysics Data System (ADS)

    Kim, Dong; Yoshino, Katsumi; Inoue, Takeo; Abe, Masaru; Uchikawa, Nobutaka

    1999-06-01

    The influence of morphology on the electrical properties of syndiotactic polypropylene (sPP) has been investigated in comparison with those of conventional isotactic polypropylene (iPP). The evolution of spherulite in sPP occurred at a lower temperature than in iPP, and the size of spherulites in sPP is much smaller than those of iPP, though the number of spherulites increases drastically. The influence of heat treatment on the electrical properties of sPP, such as conductivity and current density-electric field characteristics, is negligible in contrast to iPP, in which the conductivity increased drastically and breakdown strength decreased markedly due to growth of large spherulites upon heat treatment. These results are discussed in terms of morphological change upon heat treatment. As a result, sPP is confirmed to be an excellent candidate for a new insulating polymer for cables which can be used at a much higher operating temperature than that of widely used cables with cross-linked polyethylene (XLPE) (90°C), because of its thermal stability, stable electrical properties even following heating treatment and mechanical flexibility due to the small spherulite size and low crystallinity under any preparation and treatment conditions.

  1. Hydrothermal carbonization of biomass from landscape management - Influence of process parameters on soil properties of hydrochars.

    PubMed

    Röhrdanz, Michael; Rebling, Tammo; Ohlert, Jan; Jasper, Jan; Greve, Thomas; Buchwald, Rainer; von Frieling, Petra; Wark, Michael

    2016-05-15

    Besides pyrolysis the technology of hydrothermal carbonization (HTC) is tested to produce hydrochars for soil improvement. The chemical and physical properties of the hydrochars mainly depend on the feedstock and the process parameters reaction time and process temperature. Systematic investigations on the influences of these process parameters on soil properties of hydrochars like water holding capacity (WHC) and cation exchange capacity (CEC) are missing. In this study, a rush-rich biomass was carbonized within defined HTC process conditions under variation of reaction time and process temperature to produce hydrochars. Analysis of WHC, CEC, the elemental composition and Fourier-transform infrared spectroscopy (FT-IR) were performed to evaluate the influence of HTC process conditions on the pedological hydrochar properties. The results indicated that at increasing reaction severity (reaction time and process temperature) WHC and CEC decreased as well as the elemental O/C ratio. The decrease of WHC and CEC is based on the decrease of the hydrochar surface polarity. However, even the lowest WHC and CEC of investigated hydrochars still exceeded those of pure quartz sand by factors of 5-10. An application of hydrochars produced at severe HTC conditions could improve WHC and CEC of sandy soils. This has to be investigated in further studies.

  2. Influence of physicochemical properties of rice flour on oil uptake of tempura frying batter.

    PubMed

    Nakamura, Sumiko; Ohtsubo, Ken'ichi

    2010-01-01

    The physicochemical properties of rice flour and wheat flour influenced the oil uptake of tempura frying batter. Rice flour was better than wheat flour in the overall quality and crispness of the fried tempura batter. Rice flour resisted oil absorption more than wheat flour, and a higher level of apparent starch amylose and higher consistency/breakdown ratio of the pasting properties led to a lower oil uptake of the batter. Super hard EM10 rice showed the highest apparent amylose content and higher consistency/breakdown ratio than the other flour samples, the batter from EM10 revealing the lowest oil content after frying among all the batters examined. The apparent amylose content, consistency/breakdown ratio and oil absorption index are proposed as useful guides for oil absorption when frying from among the physicochemical properties that influence the oil content of fried batter. Our proposal for the "oil absorption index" could be a simple, although not perfect method for estimating the oil content of batter flour.

  3. Influence of the dosage of super plasticizer on properties of high performance concrete

    NASA Astrophysics Data System (ADS)

    Baroninsh, J.; Lagzdina, S.; Krage, L.; Shahmenko, G.

    2011-12-01

    High-performance concrete (HPC) is defined as concrete that meets special combinations of performance and uniformity requirements. That cannot always be achieved routinely using conventional constituents and ordinary mixing, placing, and curing practices. The objective of this study is to provide some experimental data that can be useful in engineering practice for producing HPC using conventional constituents and ordinary mixing and curing practices using less expensive raw materials. In the given study, the influence of the polycarboxylates based super plasticizer (SP) (high-range water reducer) at different dosages to the properties of HPC was investigated. SP in concrete mixtures was added with ratios of 1.0%, 1.5%, and 2.5% by weight of cement. The samples characteristics of produced concrete were compared with each other. Performance of the concrete mixes was determined for fresh and hardened concrete, which included cone test, compressive strength and porosity measurements. Obtained results indicated that increasing dosage of SP to 2.5% by weight of cement improved the performance of concrete and contributed more to the improvement of its transportability properties as well as mechanical properties, but at the same time has considerably reduced water/cement (W/C) ratio. Porosity tests of hardened concrete showed influence of SP dosage to the volume of pores accessible to water.

  4. Analysis of the Magnetic Field Influence on the Rheological Properties of Healthy Persons Blood

    PubMed Central

    Nawrocka-Bogusz, Honorata

    2013-01-01

    The influence of magnetic field on whole blood rheological properties remains a weakly known phenomenon. An in vitro analysis of the magnetic field influence on the rheological properties of healthy persons blood is presented in this work. The study was performed on blood samples taken from 25 healthy nonsmoking persons and included comparative analysis of the results of both the standard rotary method (flow curve measurement) and the oscillatory method known also as the mechanical dynamic analysis, performed before and after exposition of blood samples to magnetic field. The principle of the oscillatory technique lies in determining the amplitude and phase of the oscillations of the studied sample subjected to action of a harmonic force of controlled amplitude and frequency. The flow curve measurement involved determining the shear rate dependence of blood viscosity. The viscoelastic properties of the blood samples were analyzed in terms of complex blood viscosity. All the measurements have been performed by means of the Contraves LS40 rheometer. The data obtained from the flow curve measurements complemented by hematocrit and plasma viscosity measurements have been analyzed using the rheological model of Quemada. No significant changes of the studied rheological parameters have been found. PMID:24078918

  5. Influence of Dopant Distribution on the Plasmonic Properties of Indium Tin Oxide Nanocrystals

    SciTech Connect

    Lounis, SD; Runnerstrom, EL; Bergerud, A; Nordlund, D; Milliron, DJ

    2014-05-14

    Doped metal oxide nanocrystals represent an exciting frontier for colloidal synthesis of plasmonic materials, displaying unique optoelectronic properties and showing promise for a variety of applications. However, fundamental questions about the nature of doping in these materials remain. In this article, the strong influence of radial dopant distribution on the optoelectronic properties of colloidal indium tin oxide nanocrystals is reported. Comparing elemental depth-profiling by X-ray photoelectron spectroscopy (XPS) with detailed modeling and simulation of the optical extinction of these nanocrystals using the Drude model for free electrons, a correlation between surface segregation of tin ions and the average activation of dopants is observed. A strong influence of surface segregation of tin on the line shape of the localized surface plasmon resonance (LSPR) is also reported. Samples with tin segregated near the surface show a symmetric line shape that suggests weak or no damping of the plasmon by ionized impurities. It is suggested that segregation of tin near the surface facilitates compensation of the dopant ions by electronic defects and oxygen interstitials, thus reducing activation. A core shell model is proposed to explain the observed differences in line shape. These results demonstrate the nuanced role of dopant distribution in determining the optoelectronic properties of semiconductor nanocrystals and suggest that more detailed study of the distribution and structure of defects in plasmonic colloidal nanocrystals is warranted.

  6. Irradiating of Bulk Soybeans: Influence on Their Functional and Sensory Properties for Soyfood Processing

    NASA Technical Reports Server (NTRS)

    Chia, Chiew-Ling; Wilson, Lester A.; Boylston, Terri; Perchonok, Michele; French, Stephen

    2006-01-01

    Soybeans were chosen for lunar and planetary missions, where soybeans will be supplied in bulk or grown locally, due to their nutritive value and ability to produce oil and protein for further food applications. However, soybeans must be processed into foods prior to consumption. Radiation that soybeans would be exposed to during bulk storage prior to and during a Mars mission may influence their germination and functional properties. The influence of radiation includes the affect of surface pasteurization to ensure the astronauts safety from food-borne illnesses (HACCP, CCP), and the affect of the amount of radiation the soybeans receive during a Mars mission. Decreases in the amount of natural antioxidants free radical formation, and oxidation-induced changes in the soybean will influence the nutritional value, texture, color, and aroma of soyfoods. The objective of this study was to determine the influence of pasteurization and sterilization surface radiation on whole soybeans using gamma and electron beam radiation. The influence of 0, 1, 5, 10, and 30kGy on microbial load, germination rate, ease of processing, and quality of soymilk and tofu were determined. Surface radiation of whole dry soybeans using electron beam or gamma rays from 1-30kGy did provide microbial safety for the astronauts. However, the lower dose levels had surviving yeasts and molds. These doses caused oxidative changes that resulted in soymilk and tofu with rancid aromas. GC-MS of the aroma compounds using SPME Headspace confirmed the presence of lipid oxidation compounds. Soybean germination ability was reduced as radiation dosage increased. While lower doses may reduce these problems, the ability to insure microbial safety of bulk soybeans will be lost. Counter measures could include vacuum packaging, nitrogen flushing, added antioxidants, and radiating under freezing conditions. Doses below 1kGy need to be investigated further to determine the influence of the radiation encountered

  7. Influence of fuels, weather and the built environment on the exposure of property to wildfire

    USGS Publications Warehouse

    Penman, Trent D.; Collins, Luke S.; Syphard, Alexandra D.; Keeley, Jon E.; Bradstock, Ross A.

    2014-01-01

    Wildfires can pose a significant risk to people and property. Billions of dollars are spent investing in fire management actions in an attempt to reduce the risk of loss. One of the key areas where money is spent is through fuel treatment – either fuel reduction (prescribed fire) or fuel removal (fuel breaks). Individual treatments can influence fire size and the maximum distance travelled from the ignition and presumably risk, but few studies have examined the landscape level effectiveness of these treatments. Here we use a Bayesian Network model to examine the relative influence of the built and natural environment, weather, fuel and fuel treatments in determining the risk posed from wildfire to the wildland-urban interface. Fire size and distance travelled was influenced most strongly by weather, with exposure to fires most sensitive to changes in the built environment and fire parameters. Natural environment variables and fuel load all had minor influences on fire size, distance travelled and exposure of assets. These results suggest that management of fuels provided minimal reductions in risk to assets and adequate planning of the changes in the built environment to cope with the expansion of human populations is going to be vital for managing risk from fire under future climates.

  8. Influence of Fuels, Weather and the Built Environment on the Exposure of Property to Wildfire

    PubMed Central

    Penman, Trent D.; Collins, Luke; Syphard, Alexandra D.; Keeley, Jon E.; Bradstock, Ross A.

    2014-01-01

    Wildfires can pose a significant risk to people and property. Billions of dollars are spent investing in fire management actions in an attempt to reduce the risk of loss. One of the key areas where money is spent is through fuel treatment – either fuel reduction (prescribed fire) or fuel removal (fuel breaks). Individual treatments can influence fire size and the maximum distance travelled from the ignition and presumably risk, but few studies have examined the landscape level effectiveness of these treatments. Here we use a Bayesian Network model to examine the relative influence of the built and natural environment, weather, fuel and fuel treatments in determining the risk posed from wildfire to the wildland-urban interface. Fire size and distance travelled was influenced most strongly by weather, with exposure to fires most sensitive to changes in the built environment and fire parameters. Natural environment variables and fuel load all had minor influences on fire size, distance travelled and exposure of assets. These results suggest that management of fuels provided minimal reductions in risk to assets and adequate planning of the changes in the built environment to cope with the expansion of human populations is going to be vital for managing risk from fire under future climates. PMID:25360741

  9. Influence of grinding on service properties of VT-22 powder applied in additive technologies

    NASA Astrophysics Data System (ADS)

    Zakharov, M. N.; Rybalko, O. F.; Romanova, O. V.; Gelchinskiy, B. R.; Il’inykh, S. A.; Krashaninin, V. A.

    2017-01-01

    Powder of titanium alloy (VT-22) produced by plasma-spraying was subjected to grinding to obtain powder with size less 100 microns. These powders were sprayed by plasma unit using two types of gases, namely, air and air with methane (spraying in water and sputtering of coating on steel support). Influence of grinding time on yield of powder of required fraction was studied. Morphology and phase composition of the grinded powder and plasma sprayed one were under investigation. In the result of experiments, it appears that the grinding time genuinely influences the chemical and phase compositions, but there is no effect on physical-processing properties. For powders after plasma spraying some changes of non-metal elements content were detected by chemical analysis. Using gaseous mixture of air and methane in plasma spraying unit leads to formation of a new phase in the powder according X-ray diffraction data.

  10. Influence of substrate miscut angle on surface morphology and luminescence properties of AlGaN

    SciTech Connect

    Kusch, Gunnar Edwards, Paul R.; Bruckbauer, Jochen; Martin, Robert W.; Li, Haoning; Parbrook, Peter J.; Sadler, Thomas C.

    2014-03-03

    The influence of substrate miscut on Al{sub 0.5}Ga{sub 0.5} N layers was investigated using cathodoluminescence (CL) hyperspectral imaging and secondary electron imaging in an environmental scanning electron microscope. The samples were also characterized using atomic force microscopy and high resolution X-ray diffraction. It was found that small changes in substrate miscut have a strong influence on the morphology and luminescence properties of the AlGaN layers. Two different types are resolved. For low miscut angle, a crack-free morphology consisting of randomly sized domains is observed, between which there are notable shifts in the AlGaN near band edge emission energy. For high miscut angle, a morphology with step bunches and compositional inhomogeneities along the step bunches, evidenced by an additional CL peak along the step bunches, are observed.

  11. Chitosan as a Biomaterial: Influence of Degree of Deacetylation on Its Physiochemical, Material and Biological Properties

    PubMed Central

    Foster, Leslie John Ray; Ho, Sonia; Hook, James; Basuki, Monica; Marçal, Helder

    2015-01-01

    Chitosan is a biomaterial with a range of current and potential biomedical applications. Manipulation of chitosan degree of deacetylation (DDA) to achieve specific properties appears feasible, but studies investigating its influence on properties are often contradictory. With a view to the potential of chitosan in the regeneration of nerve tissue, the influence of DDA on the growth and health of olfactory ensheathing cells (OECs) was investigated. There was a linear increase in OEC proliferation as the DDA increased from 72 to 85%. This correlated with linear increases in average surface roughness (0.62 to 0.78 μm) and crystallinity (4.3 to 10.1%) of the chitosan films. Mitochondrial activity and membrane integrity of OECs was significantly different for OECs cultivated on chitosan with DDAs below 75%, while those on films with DDAs up to 85% were similar to cells in asynchronous growth. Apoptotic indices and cell cycle analysis also suggested that chitosan films with DDAs below 75% were cytocompatible but induced cellular stress, while OECs grown on films fabricated from chitosan with DDAs above 75% showed no significant differences compared to those in asynchronous growth. Tensile strength and elongation to break varied with DDA from 32.3 to 45.3 MPa and 3.6 to 7.1% respectively. DDA had no significant influence on abiotic and biotic degradation profiles of the chitosan films which showed approximately 8 and 20% weight loss respectively. Finally, perceived patterns in property changes are subject to change based on potential variations in DDA analysis. NMR examination of the chitosan samples here revealed significant differences depending upon which peaks were selected for integration; 6 to 13% in DDA values within individual samples. Furthermore, differences between DDA values determined here and those reported by the commercial suppliers were significant and this may also be a source of concern when selecting commercial chitosans for biomaterial research. PMID

  12. Probabilistic assessment of the influence of lake properties in long-term radiation doses to humans.

    PubMed

    Pohjola, Jari; Turunen, Jari; Lipping, Tarmo; Ikonen, Ari T K

    2016-11-01

    The assessment processes concerning the safety of nuclear waste repositories include the modelling of radionuclide transport in biosphere and the evaluation of the doses to the most affected humans. In this paper, a scenario, in which a contaminated lake is the water source for drinking water, irrigation water and watering of livestock, is presented. The objective of the paper is to probabilistically study the influence of lake properties as parameters in the assessment scenario. The properties of the lake are a result of previously conducted probabilistic studies, where the land uplift of the terrain surrounding the repositories and the formation of water bodies were studied in a 10,000-year time span using Monte Carlo simulation. The lake is formed at 3000 years from present day and the changing properties of the lake have been used in the study. The studied radionuclides (36)Cl, (135)Cs, (129)I, (237)Np, (90)Sr, (99)Tc and (238)U enter the lake with a rate of 1 Bq/year. The transport process from the lake water to humans is described and the doses (dose conversion factors) to adult humans are evaluated based on a study on average food consumption. Sensitivity analysis is used for identifying the parameters having the most influence on the outcome of the dose. Based on the results from the sensitivity analysis, the volumetric outflow rate of the lake and the volume of the lake were taken into closer consideration. The results show the influence of probabilistically derived geomorphic lake input parameters on the dose.

  13. Chitosan as a Biomaterial: Influence of Degree of Deacetylation on Its Physiochemical, Material and Biological Properties.

    PubMed

    Foster, Leslie John Ray; Ho, Sonia; Hook, James; Basuki, Monica; Marçal, Helder

    2015-01-01

    Chitosan is a biomaterial with a range of current and potential biomedical applications. Manipulation of chitosan degree of deacetylation (DDA) to achieve specific properties appears feasible, but studies investigating its influence on properties are often contradictory. With a view to the potential of chitosan in the regeneration of nerve tissue, the influence of DDA on the growth and health of olfactory ensheathing cells (OECs) was investigated. There was a linear increase in OEC proliferation as the DDA increased from 72 to 85%. This correlated with linear increases in average surface roughness (0.62 to 0.78 μm) and crystallinity (4.3 to 10.1%) of the chitosan films. Mitochondrial activity and membrane integrity of OECs was significantly different for OECs cultivated on chitosan with DDAs below 75%, while those on films with DDAs up to 85% were similar to cells in asynchronous growth. Apoptotic indices and cell cycle analysis also suggested that chitosan films with DDAs below 75% were cytocompatible but induced cellular stress, while OECs grown on films fabricated from chitosan with DDAs above 75% showed no significant differences compared to those in asynchronous growth. Tensile strength and elongation to break varied with DDA from 32.3 to 45.3 MPa and 3.6 to 7.1% respectively. DDA had no significant influence on abiotic and biotic degradation profiles of the chitosan films which showed approximately 8 and 20% weight loss respectively. Finally, perceived patterns in property changes are subject to change based on potential variations in DDA analysis. NMR examination of the chitosan samples here revealed significant differences depending upon which peaks were selected for integration; 6 to 13% in DDA values within individual samples. Furthermore, differences between DDA values determined here and those reported by the commercial suppliers were significant and this may also be a source of concern when selecting commercial chitosans for biomaterial research.

  14. Influence of pH on the properties of PVA capped silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ajitha, B.; Reddy, P. Sreedhara

    2013-06-01

    Silver nanoparticles were synthesized by chemical reduction method using ascorbic acid as reductant and PVA as surfactant and studied the pH influence on the structural, compositional and optical properties of silver nanoparticles. Broadened XRD peaks confirmed the formation of small nanosized silver nanoparticles with face centered cubic (FCC) structure. The particle size decreased with increasing pH value. We have observed blue shift of Surface Plasmon Resonance (SPR) band from optical absorption spectra. The obtained nanoparticles were well dispersed in water, ethanol and polar solvents and thus more suitable for biocompatible.

  15. Influence of Space-Flight Factors on the Properties of Microorganisms, Producers of Biologically Active Substances

    NASA Astrophysics Data System (ADS)

    Krasheninnikova, T. K.; Kanaeva, E. N.; Ukraintsev, A. D.; Smolyanaya, G. L.; Kuznetsov, N. V.; Panasyuk, M. I.; Shcherbakov, G. Ya.

    2001-07-01

    The following substances were isolated under the influence of space-flight factors in cosmic experiments aboard the Mirorbital station: an MIB-90 monoisolant, which is distinguished by its morphological and biochemical properties and enhanced productivity, was isolated from the Bacillus thuringiensis ssp. Kurstaki var. Z-52culture, which is a producer of the plant protection agent Lepidocide; and MIA-74 and MIP-89 monoisolants, which are highly active toward heavy petroleum fractions (C23 C33), were isolated from the Arthrobacter OC-1culture, which is a producer of biodegradants for petroleum.

  16. Influence of length of hot soak of melt on properties of lithium greases with additives

    SciTech Connect

    El'-Shaban, I.; Fuks, I.G.; Safi, M.; Uvarova, E.M.; Yaroshevich, S.V.

    1983-11-01

    An extension of the time during which the melt is hot-soaked at the maximum cooking temperature tends to improve the dispersion of the thickening agent in the oil but also increases oxidation and evaporation. This paper investigates the influence of hot-soaking the soap/oil melt of Li greases on the effectiveness of selected additives. Extending the hot-soak time in manufacturing Li greases leads to oxidation as well as accumulation of oxygen-containing substances in the grease. The end result is poorer properties of the grease.

  17. The influence of the semiconductor and dielectric properties on surface flashover in silicon-dielectric systems

    SciTech Connect

    Gradinaru, G.; Madangarli, V.P.; Sudarshan, T.S. . Dept. of Electrical and Computer Engineering)

    1994-07-01

    New experimental results on surface flashover are reported for high field silicon-dielectric systems. Different conditions of the lateral surface, contacts and ambient dielectrics have been studied. The strong influence of the semiconductor quality, and that of the dielectric properties, on the prebreakdown and breakdown response of the system, is demonstrated. All experimental results strongly support the conclusion that surface flashover in silicon systems is a physical process totally different from semiconductor surface breakdown. This conclusion has important practical application in the improvement of the performance of photoconductive power switches, severely limited by premature breakdown effects.

  18. Lignocellulosic nanofibers from triticale straw: The influence of hemicelluloses and lignin in their production and properties.

    PubMed

    Tarrés, Quim; Ehman, Nanci Vanesa; Vallejos, María Evangelina; Area, Maria Cristina; Delgado-Aguilar, Marc; Mutjé, Pere

    2017-05-01

    The present work aims to determine the influence of hemicellulose and lignin content in the production of lignocellulosic nanofibers (LCNF) from triticale straws. Triticale straws were digested and then gradually delignified, preserving as much hemicelluloses as possible. The obtained LCNF was characterized and used as paper strength additive, observing that hemicellulose and lignin have a key role on the final properties thereof, as well as on their reinforcing potential as paper additive, obtaining LCNF with the same paper reinforcing potential than CNF obtained by TEMPO ((2,2,6,6-Tetramethyl-piperidin-1-yl)oxyl) mediated oxidation.

  19. Catalytic activity of metallic nanoisland coatings. The influence of size effects on the recombination properties

    NASA Astrophysics Data System (ADS)

    Tomilina, O. A.; Berzhansky, V. N.; Tomilin, S. V.; Shaposhnikov, A. N.

    2016-08-01

    The results of investigations of the quantum-size effects influence on selective properties of heterogeneous nanocatalysts are presents. As etalon exothermic reaction was used the reaction of atomic hydrogen recombination. The nanostructured Pd and Pt films on Teflon substrate were used as a samples of heterogeneous nanocatalysts. It was shown that for nanoparticles with various sizes the catalytic activity has the periodic dependence. It has been found that for certain sizes of nanoparticles their catalytic activity is less than that of Teflon substrate.

  20. PVC/CaCO3 Nanocomposites: Influence of nanoparticle surface treatment on properties

    NASA Astrophysics Data System (ADS)

    Bonadies, Irene; Avella, Maurizio; Avolio, Roberto; Carfagna, Cosimo; Emanuela Errico, Maria; Gentile, Gennaro

    2010-06-01

    The influence of nanosized calcium carbonate on the gelation process, thermal stability and mechanical properties of rigid poly(vinyl chloride) has been studied. The gelation time of rigid PVC/calcium carbonate nanocomposites depends on the percentage and superficial treatment of CaCO3. The results of thermogravimetric analysis underline an improvement of the thermal stability as a function of the surface modifier. Finally, the flexural modulus, the flexural strength as well as the critical stress intensity factor increase with the addition of poly(acrylic acid) (PAA) or poly(butadiene-co-acrilonitrile-co-acrylic acid) (PBAA) coated nanoparticles.

  1. Thin Ag films. Influence of substrate and postdeposition treatment on morphology and optical properties

    SciTech Connect

    Roark, S.E.; Rowlen, K.L. )

    1994-01-15

    In an effort to understand the experimental parameters that influence thin metal film morphology and optical characteristics, thin Ag films are examined with a combination of atomic force microscopy (AFM), optical absorption, and surface-enhanced Raman spectroscopy (SERS). The morphology of 5 nm of Ag vapor deposited onto glass, derivatized glass, Formvar-coated glass, and mica is explored. The substrate is found to have a large effect on both Ag film surface morphology and optical properties. In addition, micrographs of a Ag film before and after exposure to solvent suggest solvent-induced morphological changes. 32 refs., 8 figs., 5 tabs.

  2. Solidification rate influence on orientation and mechanical properties of MAR-M-246+Hf

    NASA Technical Reports Server (NTRS)

    Hamilton, D.

    1983-01-01

    The influence of solidification rates on the orientation and mechanical properties of MAR-M-246+Hf was studied. The preferred orientation was found to be (001) for single crystals, with all samples with 45 degrees of (001). Tensile tests were performed at room temperature. The anisotropy of directionally solidified MAR-M-246+Hf was demonstrated by gage section deformation. Dendrite arm spacing and crystal growth were found to depend on solidification rates and source material conditions. The greatest strength occurred at lower solidification rates. Some single crystals were grown by control of growth rates without seeding.

  3. The influence of yarn treatment on the tensile properties of biocomposites

    NASA Astrophysics Data System (ADS)

    Širvaitienė, Anne; Jankauskaitė, Virginija; Bekampienė, Paulė; Sankauskaitė, Audronė

    2012-07-01

    The aim of this work was to investigate the influence of cotton and linen yarns treatments at different hierarchical levels on the biocomposite tensile properties. The biodegradable poly(lactic acid) (PLA) resin was used as the matrix polymer. The water based mercerization and low pressure plasma treatment were applied for chemical modification of yarns macro- and microfibrils. To improve fiber orientation of fibre bundles and single fibers the pretension of yarn was used. It was obtained that the most efficient is the complex yarns treatment, plasma treatment with subsequent pre-tension, where especially notable was the positive effect of low-pressure plasma.

  4. Surface coating influence on elastic properties of spruce wood by means of holographic vibration mode visualization

    NASA Astrophysics Data System (ADS)

    Bongova, M.; Urgela, Stanislav

    1999-07-01

    Physicoacoustical properties of wood influenced by surface coating are studied by modal analysis. Resonant spruce plates were coated by stain, nitrocellulose varnish, special violin paint and shellac. The modal testing was performed by electronic speckle pattern interferometry. For this purpose, equipment called VIBROVIZER was used. The collected values of physicoacoustical characteristics (density, Young's modulus, acoustic constant) were compared using the graphic plots of data. The 3D plots help to evaluate wooden plates from a viewpoint of the quality control. This fact offers new opportunity for musical instrument manufacturers.

  5. The influence of turbid medium properties on object visibility in optical Kerr gated imaging

    NASA Astrophysics Data System (ADS)

    Zhan, Pingping; Si, Jinhai; Tan, Wenjiang; Liu, Xin; Wu, Bin; Xu, Shichao; Chen, Feng; Hou, Xun

    2014-01-01

    In this paper, we demonstrate femtosecond optical Kerr gated imaging of an object hidden behind a highly turbid medium. The influence of turbid medium properties on image contrast has been investigated. Experimental and Monte Carlo simulation results show that for a given optical density, the image contrast of direct imaging without an optical Kerr gate decreases with the increase of the scattering particle size or the decrease of the thickness of the turbid medium. Compared with direct imaging, optical Kerr gated imaging has a better image contrast as it eliminates more scattered photons effectively. Qualitative comparisons between experiments and simulations show good agreement.

  6. Influence of cobalt, tantalum, and tungsten on the microstructure and mechanical properties of superalloy single crystals

    NASA Technical Reports Server (NTRS)

    Nathal, M. V.; Ebert, L. J.

    1982-01-01

    The influence of Co, Ta, and W on the microstructure and mechanical properties of nickel base super-alloy single crystals was investigated. A matrix of alloys was based on Mar-M 247 stripped of C, B, Zr, and Hf. The microstructures of the alloys were examined using optical and electron microscopy, phase extraction, X-ray diffraction, and differential thermal analysis. Tensile and creep-rupture tests were performed at 1000 C. An increase in tensile and creep strength resulted when Co was removed from alloys containing high refractory metal contents, but Co effects were negligible for alloys with lower refractory metal levels. In the composition range studied, W was more effective than Ta in increasing the creep resistance. The mechanical properties are discussed in relation to the microstructures of the alloys.

  7. How Far Does a Receptor Influence Vibrational Properties of an Odorant?

    PubMed Central

    Kongsted, Jacob; Solov’yov, Ilia A.

    2016-01-01

    The biophysical mechanism of the sense of smell, or olfaction, is still highly debated. The mainstream explanation argues for a shape-based recognition of odorant molecules by olfactory receptors, while recent investigations suggest the primary olfactory event to be triggered by a vibrationally-assisted electron transfer reaction. We consider this controversy by studying the influence of a receptor on the vibrational properties of an odorant in atomistic details as the coupling between electronic degrees of freedom of the receptor and the vibrations of the odorant is the key parameter of the vibrationally-assisted electron transfer. Through molecular dynamics simulations we elucidate the binding specificity of a receptor towards acetophenone odorant. The vibrational properties of acetophenone inside the receptor are then studied by the polarizable embedding density functional theory approach, allowing to quantify protein-odorant interactions. Finally, we judge whether the effects of the protein provide any indications towards the existing theories of olfaction. PMID:27014869

  8. Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

    PubMed

    Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films.

  9. Influence of various surfactants on magnetic property of cobalt ferrite prepared by Co-precipitation technique

    NASA Astrophysics Data System (ADS)

    Solanki, Neha; Khatri, Hemal; Jotania, R. B.

    2016-05-01

    Cobalt Ferrite (CoFe2O4) particles were synthesised using a Co-precipitation method. Influence of three different surfactants i.e. (1) Cationic - CTAB (Cetyl Tri-Methyl Ammonium Bromide), (2) Anionic - SDBS (Sodium Dodecyl Benzene Sulphonate) and (3) Nonionic - Triton X-100, on magnetic property of Cobalt Ferrite were investigated. Magnetic property of Cobalt ferrite powder was studied at room temperature using Vibrating Sample Measurements (VSM) technique under an applied magnetic field of 15kOe. The results show maximum value of saturation magnetization - Ms (81.87 emu/g) for the sample synthesised without surfactant and Coercivity value found maximum (2086 kOe) for the sample synthesized in presence of surfactant SDBS.

  10. Influence of powder properties on the sintering of polyaromatic mesophases to high-strength isotropic graphite

    SciTech Connect

    Braun, M.; Gschwindt, A.; Hoffmann, W.R.

    1995-09-01

    The paper reviews the state of the art in sintering of polyaromatic mesophase powders to high-strength isotropic carbons and graphites. Synthesis of mesophase pitches from different precursor materials (petroleum- and coal tar pitch) using a net thermal or a catalyzed process, the preparation of mesophase powders from mesophase pitches and the influence of the powder properties on the sintering are discussed. Special attention is given to the role of thermoplasticity and the particle size of the mesophase powder as key properties for the production of high-strength carbons and graphites. After a graphitization treatment, isotropic graphites with a flexural strength of 160 MPa can be obtained, a value which probably represents an upper limit.

  11. Influence of tragacanth gum in egg white based bioplastics: Thermomechanical and water uptake properties.

    PubMed

    López-Castejón, María Luisa; Bengoechea, Carlos; García-Morales, Moisés; Martínez, Inmaculada

    2016-11-05

    This study aims to extend the range of applications of tragacanth gum by studying its incorporation into bioplastics formulation, exploring the influence that different gum contents (0-20wt.%) exert over the thermomechanical and water uptake properties of bioplastics based on egg white albumen protein (EW). The effect of plasticizer nature was also evaluated through the modification of the water/glycerol ratio within the plasticizer fraction (fixed at 40wt.%). The addition of tragacanth gum generally yielded an enhancement of the water uptake capacity, being doubled at the highest content. Conversely, presence of tragacanth gum resulted in a considerable decrease in the bioplastic mechanical properties: both tensile strength and maximum elongation were reduced up to 75% approximately when compared to the gum-free system. Ageing of selected samples was also studied, revealing an important effect of storage time when tragacanth gum is present, possibly due to its hydrophilic character.

  12. Influence of carbonyl iron particle coating with silica on the properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Małecki, P.; Królewicz, M.; Hiptmair, F.; Krzak, J.; Kaleta, J.; Major, Z.; Pigłowski, J.

    2016-10-01

    In this paper, the influence of encapsulating carbonyl iron particles with various silica coatings on the properties of magnetorheological elastomers (MREs) was investigated. A soft styrene-ethylene-butylene-styrene thermoplastic elastomer was used as the composite’s polymer matrix. Spherical carbonyl iron powder (CIP) acted as the ferromagnetic filler. In order to improve the metal-polymer interaction, carbonyl iron particles were coated with two types of single and six types of double silica layers. The first layer was created through a TMOS or TEOS hydrolysis whereas the second one was composed of organosilanes. The mechanical properties of MREs containing 38.5 vol% of CIP were analysed under dynamic loading conditions. To investigate the magnetorheological effect in these composites, a 430 mT magnetic field, generated by an array of permanent magnets, was applied during testing. The results revealed that the magnetomechanical response of the MREs differs substantially, depending on the kind of particle coating.

  13. Mesomeric Effects of Graphene Modified with Diazonium Salts: Substituent Type and Position Influence its Properties.

    PubMed

    Bouša, Daniel; Jankovský, Ondřej; Sedmidubský, David; Luxa, Jan; Šturala, Jiří; Pumera, Martin; Sofer, Zdeněk

    2015-12-01

    In the last decade, graphene and graphene derivatives have become some of the most intensively studied materials. Tuning of the electronic and electrochemical properties of graphene is of paramount importance. In this study, six diazonium-modified graphenes containing different functional groups according to the diazonium salt precursor were investigated. These diazonium moieties have a strong mesomeric (resonance) effect and act as either electron-donating or -withdrawing species. Different graphene precursors, such as thermally and chemically reduced graphenes were studied. All the products were characterized in detail by elemental combustion analysis, FTIR spectroscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. Resistivity and zeta potential measurements were consistent with theoretical (DFT) calculations. The results show that chemical modification of graphene by diazotation strongly influences its properties, creating a huge application potential in microelectronics, energy storage and conversion devices, and electrocatalysis.

  14. The influence of processing on microstructure and properties of iron aluminides

    SciTech Connect

    Wright, R.N.; Wright, J.K.

    1995-08-01

    An Fe-28%Al alloy containing 5% Cr has been synthesized by reaction of elemental powders, followed by consolidation using hot isostatic pressing or hot extrusion. The resulting materials are fully dense, homogeneous, and have a grain size of less than 5{mu}m. Processing strongly influences the propensity toward secondary recrystallization. While HIPped material is extremely resistant to grain growth, under some circumstances hot extruded material undergoes secondary recrystallization, resulting in grain sizes as large as 25 millimeters. Elevated temperature tensile properties and strain rate sensitivities are reported for fine and very coarse grained materials. Grain boundary sliding is not a significant deformation mode for any of the materials. The properties are compared to those of Fe{sub 3}Al processed from conventional hot extruded prealloyed. powder. It has been found that the reaction synthesized materials generally have superior elevated temperature tensile strength.

  15. Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes: A comparative study

    SciTech Connect

    Singh, Ram Sevak

    2015-11-15

    Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes (CNTs and BNNTs) is systematically studied using first principle calculations based on density functional theory. Energy band structures and density of states of optimized zigzag (5, 0), armchair (3, 3), and chiral (4, 2) structures of CNT and BNNT are calculated. Oxygen doping in zigzag CNT exhibits a reduction in metallicity with opening of band gap in near-infrared region while metallicity is enhanced in armchair and chiral CNTs. Unlike oxygen-doped CNTs, energy bands are drastically modulated in oxygen-doped zigzag and armchair BNNTs, showing the nanotubes to have metallic behaviour. Furthermore, oxygen impurity in chiral BNNT induces narrowing of band gap, indicating a gradual modification of electronic band structure. This study underscores the understanding of different electronic properties induced in CNTs and BNNTs under oxygen doping, and has potential in fabrication of various nanoelectronic devices.

  16. Investigations on the Mechanical Properties of Conducting Polymer Coating-Substrate Structures and Their Influencing Factors

    PubMed Central

    Wang, Xi-Shu; Tang, Hua-Ping; Li, Xu-Dong; Hua, Xin

    2009-01-01

    This review covers recent advances and work on the microstructure features, mechanical properties and cracking processes of conducting polymer film/coating- substrate structures under different testing conditions. An attempt is made to characterize and quantify the relationships between mechanical properties and microstructure features. In addition, the film cracking mechanism on the micro scale and some influencing factors that play a significant role in the service of the film-substrate structure are presented. These investigations cover the conducting polymer film/coating nucleation process, microstructure-fracture characterization, translation of brittle-ductile fractures, and cracking processes near the largest inherent macromolecule defects under thermal-mechanical loadings, and were carried out using in situ scanning electron microscopy (SEM) observations, as a novel method for evaluation of interface strength and critical failure stress. PMID:20054470

  17. [Influence of vermiculite particles on antioxidant properties of cultural medium of Bacillus subtilis IMV V-7023].

    PubMed

    Skorokhod, I A; Kudrish, I K

    2014-01-01

    It is shown that in the process of cultivation of Bacillus subtilis IMV V-7023 in the medium with vermiculite (1.5-5.0 g/l) one can observe the oppressing of some indexes of antioxidant properties of cultural medium of bacteria. In particular, a decline of hydroxyl radical scavenging activity in the Fenton reaction by 2.8-11.6%, ability to inhibit formation of malondialdehyde - by 4.4-13.1% and inactivation of 2,2'-Diphenyl-l-picrylhydrazyl (DPPH·) radical - by 3.1-8.5% were observed. Thus oxidant activity increased substantially. Besides oppressing influence of particles of vermiculite on protector properties of the cultural medium of bacilli it is found out that with the increase of the content of dispersible material in the nutrient medium the reducing power of cultural medium of these bacteria increased.

  18. Influence of sintering temperature on structure, microstructure and piezoelectric properties of doped BZT-BCT ceramics

    NASA Astrophysics Data System (ADS)

    Dang, Anh Tuan; Vo, Thanh Tung; Truong, Van Chuong; Le, Van Hong

    2017-01-01

    This work reports the influence of sintering temperature on structure, microstructure and piezoelectric properties of 0.48 Ba(Zr0.2Ti0.8)O3-0.52 (Ba0.7Ca0.3)TiO3(BZT-BCT) doped with ZnO nanoparticle ceramics manufactured by a conventional solid state reaction method. By increasing sintering temperature, the piezoelectric behaviors were improved and rose up to the best parameters at a sintering temperature of 1450∘C (d33 = 576 pC/N and kp = 0.55). The corresponding properties of undoped BZT-BCT ceramics were investigated as a comparison. The received results show that the sintering behavior and piezo-parameters of doped BZT-BCT samples are better than the undoped BZT-BCT samples at each sintering temperature.

  19. Calcification of coronary arteries and abdominal aorta in relation to traditional and novel risk factors of atherosclerosis in hemodialysis patients

    PubMed Central

    2013-01-01

    Background Process of accelerated atherosclerosis specific for uremia increases cardiovascular risk in patients with chronic kidney disease (CKD) and may be influenced by the different structure of arteries. The study assesses the influence of traditional and novel risk factors on calcification of coronary arteries (CAC) and abdominal aorta (AAC) in hemodialysis patients (HD). Methods CAC and AAC were assessed by CT in 104 prevalent adult HD and 14 apparently healthy subjects with normal kidney function (control group). Mineral metabolism parameters, plasma levels of FGF-23, MGP, osteoprotegerin, osteopontin, fetuin-A, CRP, IL-6 and TNF-α were measured. Results CAC and AAC (calcification score ≥ 1) were found in 76 (73.1%) and 83 (79.8%) HD respectively, more frequent than in the control group. In 7 HD with AAC no CAC were detected. The frequency and severity of calcifications increased with age. Both CAC and AAC were more frequently detected in diabetics (OR = 17.37 and 13.00, respectively). CAC score was significantly greater in males. CAC and AAC scores were correlated significantly with pack-years of smoking and plasma osteoprotegrin levels. However the independent contribution of plasma osteoprotegerin levels was not confirmed in multiple regression analysis. Age (OR = 1.13) and hemodialysis vintage (OR = 1.14) were the independent risk factor favoring the occurrence of CAC; while age (OR = 1.20) was the only predictor of AAC occurrence in HD. Conclusions 1. AAC precedes the occurrence of CAC in HD patients. 2. The exposition to uremic milieu and systemic chronic microinflammation has more deteriorative effect on the CAC than the AAC. PMID:23317172

  20. Bioacceptable and calcification-resistant membranes and interfaces for implantable sensors and devices

    NASA Astrophysics Data System (ADS)

    Galeska, Izabela Ewa

    The rational design and characterization of biocompatible, semipermeable and calcification resistant materials to serve as an outer membrane for implantable glucose biosensors, was the primary focus of this research. Multilayered films of polyanions (i.e. Nafion(TM), a perfluorinated ionomer, and Humic Acids (HAs), naturally occurring biopolymers), fabricated by layer-by-layer self-assembly with oppositely charged ferric ions were investigated as potential membranes. Spectroscopic ellipsometry and quartz crystal microbalance studies point towards a stepwise film growth, with growth rates of 47 and 24.3 nm per layer (for Nafion and HAs respectively) that can be altered depending on the pH and ionic strength of the polyanion solution. Nafion/Fe3+ assembled films exhibited an order of magnitude lower calcification as compared to dip-coated Nafion films and did not require annealing to impart insolubility. Similarly the HAs/Fe3+ films were also devoid of calcification, even after four-week immersion in DMEM cell culture media. Significantly, in vivo studies on the HAs/Fe3 films point to their biocompatibility as demonstrated by mild tissue reaction. These results, along with controllable glucose permeability, could prove vital in prolonging the lifetime of implantable biosensors. Additionally in effort to minimize tissue trauma upon implantation, novel poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel composites were investigated for dexamethasone delivery. A release rate of 25 to 40% over one month, following a zero order profile, was achieved by preferential adsorption of surface active polyacids (poly(acrylic acid), Nafion and HAs) on the hydrogel dispersed microspheres. Environmental scanning electron microscopy investigation on the degradation mechanism of the microspheres pointed towards their slow homogeneous degradation in the PVA hydrogels that was significantly surface-accelerated in the presence of polyacids. The physico

  1. Optical properties of mice skin for optical therapy relevant wavelengths: influence of gender and pigmentation

    NASA Astrophysics Data System (ADS)

    Sabino, C. P.; Deana, A. M.; Silva, D. F. T.; França, C. M.; Yoshimura, T. M.; Ribeiro, M. S.

    2015-03-01

    Red and near-infrared light have been widely employed in optical therapies. Skin is the most common optical barrier in non-invasive techniques and in many cases it is the target tissue itself. Consequently, to optimize the outcomes brought by lightbased therapies, the optical properties of skin tissue must be very well elucidated. In the present study, we evaluated the dorsal skin optical properties of albino (BALB/c) and pigmented (C57BL/6) mice using the Kubelka-Munk photon transport model. We evaluated samples from male and female young mice of both strains. Analysis was performed for wavelengths at 630, 660, 780, 810 and 905 nm due to their prevalent use in optical therapies, such as low-level light (or laser) and photodynamic therapies. Spectrophotometric measurements of diffuse transmittance and reflectance were performed using a single integrating sphere coupled to a proper spectrophotometer. Statistic analysis was made by two-way ANOVA, with Tukey as post-test and Levenne and Shapiro-Wilks as pre-tests. Statistical significance was considered when p<0.05. Our results show only a slight transmittance increment (<10 %) as wavelengths are increased from 630 to 905 nm, and no statistical significance was observed. Albino male mice present reduced transmittance levels for all wavelengths. The organization and abundance of skin composing tissues significantly influence its scattering optical properties although absorption remains constant. We conclude that factors such as subcutaneous adiposity and connective tissue structure can have statistically significant influence on mice skin optical properties and these factors have relevant variations among different gender and strains.

  2. Evaluation of Beeswax Influence on Physical Properties of Lipstick Using Instrumental and Sensory Methods

    PubMed Central

    Kasparaviciene, Giedre; Savickas, Arunas; Kalveniene, Zenona; Velziene, Saule; Kubiliene, Loreta

    2016-01-01

    The aim of this study was to optimize the lipsticks formulation according to the physical properties and sensory attributes and investigate the relationship between instrumental and sensory analyses and evaluate the influence of the main ingredients, beeswax and oil, with analysis of lipsticks properties. Central composite design was used to optimize the mixture of oils and beeswax and cocoa butter for formulation of lipsticks. Antioxidant activity was evaluated by DPPH free radical scavenging method spectrophotometrically. Physical properties of lipsticks melting point were determined in a glass tube; the hardness was investigated with texture analyzer. Sensory analysis was performed with untrained volunteers. The optimized mixture of sea buckthorn oil and grapeseed oil mixture ratio 13.96 : 6.18 showed the highest antioxidative activity (70 ± 0.84%) and was chosen for lipstick formulation. According to the sensory and instrumental analysis results, optimal ingredients amounts for the lipstick were calculated: 57.67% mixture of oils, 19.58% beeswax, and 22.75% cocoa butter. Experimentally designed and optimized lipstick formulation had good physical properties and high scored sensory evaluation. Correlation analysis showed a significant relationship between sensory and instrumental evaluations. PMID:27994631

  3. Compound Microstructures and Wax Layer of Beetle Elytral Surfaces and Their Influence on Wetting Properties

    PubMed Central

    Sun, Mingxia; Liang, Aiping; Watson, Gregory S.; Watson, Jolanta A.; Zheng, Yongmei; Jiang, Lei

    2012-01-01

    A beetles’ first line of defense against environmental hazards is their mesothoracic elytra – rigid, protective forewings. In order to study the interaction of these wings with water, the surface microstructures of various beetles’ elytra were observed by Environment Scanning Electron Microscopy (ESEM) and Atomic Force Microscopy (AFM). Chemistry components were ascertained using X-ray photoelectron spectroscopy (XPS). All the beetles of various habitats (including desert, plant, dung, land and water) exhibited compound microstructures on their elytra. The wetting properties of these elytra were identified using an optical contact angle meter. In general the native elytra exhibited hydrophilic or weak hydrophobic properties with contact angles (CAs) ranging from 47.5° to 109.1°. After treatment with chloroform, the CAs all increased on the rougher elytral surfaces. The presence of wax is not the only determinant of hydrophobic properties, but rather a combination with microscopic structures found on the surfaces. Irregularities and the presence or absence of tiny cracks, hairs (or setae), pores and protrusions are important factors which influence the wetting properties. Rougher elytral surfaces tended to present a stronger hydrophobicity. Effects on hydrophobicity, such as surface microstructures, chemistry, environment and aging (referring to the time after emergence), are also included and discussed. Our results also provide insights into the motion of water droplets when in contact with beetle elytra. PMID:23056414

  4. Evaluation of Beeswax Influence on Physical Properties of Lipstick Using Instrumental and Sensory Methods.

    PubMed

    Kasparaviciene, Giedre; Savickas, Arunas; Kalveniene, Zenona; Velziene, Saule; Kubiliene, Loreta; Bernatoniene, Jurga

    2016-01-01

    The aim of this study was to optimize the lipsticks formulation according to the physical properties and sensory attributes and investigate the relationship between instrumental and sensory analyses and evaluate the influence of the main ingredients, beeswax and oil, with analysis of lipsticks properties. Central composite design was used to optimize the mixture of oils and beeswax and cocoa butter for formulation of lipsticks. Antioxidant activity was evaluated by DPPH free radical scavenging method spectrophotometrically. Physical properties of lipsticks melting point were determined in a glass tube; the hardness was investigated with texture analyzer. Sensory analysis was performed with untrained volunteers. The optimized mixture of sea buckthorn oil and grapeseed oil mixture ratio 13.96 : 6.18 showed the highest antioxidative activity (70 ± 0.84%) and was chosen for lipstick formulation. According to the sensory and instrumental analysis results, optimal ingredients amounts for the lipstick were calculated: 57.67% mixture of oils, 19.58% beeswax, and 22.75% cocoa butter. Experimentally designed and optimized lipstick formulation had good physical properties and high scored sensory evaluation. Correlation analysis showed a significant relationship between sensory and instrumental evaluations.

  5. Phase transformation in thiamine hydrochloride tablets: Influence on tablet microstructure, physical properties, and performance.

    PubMed

    Chakravarty, Paroma; Suryanarayanan, Raj; Govindarajan, Ramprakash

    2012-04-01

    The objective of this article was to monitor phase transformation in thiamine hydrochloride, from a nonstoichiometric hydrate (NSH) to a hemihydrate (HH), in stored tablets, prepared both by direct compression and wet granulation, and to relate the storage-induced phase transformation with changes in tablet microstructure, physical properties, and performance. Raman spectroscopy revealed complete NSH → HH transformation in tablets, within 30 h of storage at 40°C/75% relative humidity. When the tablets were prepared by wet granulation of NSH alone, there was a marked increase in both tablet volume and hardness on storage. However, when microcrystalline cellulose (MCC) was included in granulation, the resulting stored tablets also exhibited a pronounced increase in disintegration time. In contrast, tablets prepared by dry processing via compression of a NSH-MCC physical mixture did not exhibit any changes in properties, despite the in situ solid form conversion. Scanning electron microscopy revealed growth of needle-like HH crystals in all stored tablets and mercury porosimetry revealed considerable changes in the pore size distribution during storage. Longer storage led to crystal growth (Ostwald ripening), causing further gradual but less dramatic changes in properties. The phase transformation and the complex interparticulate associations in the tablet influenced the changes in tablet microstructure, compact physical properties, and product behavior.

  6. The influence of physical activity during youth on structural and functional properties of the Achilles tendon.

    PubMed

    Lenskjold, A; Kongsgaard, M; Larsen, J O; Nielsen, R H; Kovanen, V; Aagaard, P; Kjaer, M; Magnusson, S P

    2015-02-01

    Achilles tendinopathy is a highly prevalent sports injury. Animal studies show a growth response in tendons in response to loading in the immature phase but not after puberty maturation. The aim of this investigation was to examine the structural and material properties in long distance runners who were either physically active (HAY) or inactive (LAY) in young age. Twelve men in HAY group and eight men in LAY group participated. Structural, functional, and biochemical properties of Achilles tendon were estimated from magnetic resonance imaging, ultrasound video recordings, mechanical tests, and tendon biopsies, respectively. There was no difference between the groups with respect to tendon cross-sectional area or tendon free length. There was no difference between the groups with respect to maximal force or mechanical properties. The collagen content, enzymatic and nonenzymatic cross-link density did not differ between the groups, nor did collagen fibril density, diameter, and area. There was a correlation between age and pentosidine/collagen within the groups [(HAY: P < 0.05 and r(2) = 0.47) and (LAY: P < 0.05 and r(2) = 0.52)]. The data suggest that high or low activity during youth did not appreciably influence the mechanical, structural, or biochemical properties of the Achilles tendon in adult long distance runners.

  7. Influence of soil properties on the bioaccumulation and effects of arsenic in the earthworm Eisenia andrei.

    PubMed

    Romero-Freire, A; Peinado, F J Martín; Ortiz, M Díez; van Gestel, C A M

    2015-10-01

    This study aimed at assessing the influence of soil properties on the uptake and toxicity effects of arsenic in the earthworm Eisenia andrei exposed for 4 weeks to seven natural soils spiked with different arsenic concentrations. Water-soluble soil concentrations (AsW) and internal As concentrations in the earthworms (AsE) were greatly different between soils. These two variables were highly correlated and were key factors in earthworm toxicity response. AsW was explained by some soil properties, such as the pH, calcium carbonate content, ionic strength, texture or oxide forms. Toxicity showed a clear variation between soils, in some cases without achieving 50 % adverse effect at the highest As concentration added (600 mg kg(-1)). Nevertheless, soil properties did not show, in general, a high relation with studied toxicity endpoints, although the high correlation with AsW could greatly reduce indirectly As bioavailability and toxicity risk for earthworms. Obtained results suggest that soil properties should be part of the criteria to establishing thresholds for contaminated soils because they will be key in controlling As availability and thus result in different degrees of toxicity.

  8. Computed Tomographic Distinction of Intimal and Medial Calcification in the Intracranial Internal Carotid Artery

    PubMed Central

    Vos, Annelotte; Van Hecke, Wim; Vink, Aryan; Bleys, Ronald L. A. W.; Verdoorn, Daphne; Mali, Willem P. Th. M.; Hendrikse, Jeroen; Koek, Huiberdina L.; de Jong, Pim A.; De Vis, Jill B.

    2017-01-01

    Background Intracranial internal carotid artery (iICA) calcification is associated with stroke and is often seen as a proxy of atherosclerosis of the intima. However, it was recently shown that these calcifications are predominantly located in the tunica media and internal elastic lamina (medial calcification). Intimal and medial calcifications are thought to have a different pathogenesis and clinical consequences and can only be distinguished through ex vivo histological analysis. Therefore, our aim was to develop CT scoring method to distinguish intimal and medial iICA calcification in vivo. Methods First, in both iICAs of 16 cerebral autopsy patients the intimal and/or medial calcification area was histologically assessed (142 slides). Brain CT images of these patients were matched to the corresponding histological slides to develop a CT score that determines intimal or medial calcification dominance. Second, performance of the CT score was assessed in these 16 patients. Third, reproducibility was tested in a separate cohort. Results First, CT features of the score were circularity (absent, dot(s), <90°, 90–270° or 270–360°), thickness (absent, ≥1.5mm, or <1.5mm), and morphology (indistinguishable, irregular/patchy or continuous). A high sum of features represented medial and a lower sum intimal calcifications. Second, in the 16 patients the concordance between the CT score and the dominant calcification type was reasonable. Third, the score showed good reproducibility (kappa: 0.72 proportion of agreement: 0.82) between the categories intimal, medial or absent/indistinguishable. Conclusions The developed CT score shows good reproducibility and can differentiate reasonably well between intimal and medial calcification dominance in the iICA, allowing for further (epidemiological) studies on iICA calcification. PMID:28060941

  9. Inhibition of CEM calcification by the sequential pretreatment with ethanol and EDTA.

    PubMed

    Singla, Anuj; Lee, Chi H

    2003-03-15

    The major object of the present study is to optimize the anticalcification activity of ethanol on bioprosthetic heart valve (BHV) calcification. We hypothesize that the chelating agent, in combination with ethanol, will synergistically prevent aortic wall calcification. Collagen-elastin matrix (CEM) was developed as a calcifiable matrix for simulating the calcification process of implantable biomaterials. The efficacy of the combination effects of ethanol and EDTA on the calcification process of CEMs was investigated by implanting them after pretreatment with various conditions of ethanol and EDTA in the rat subdermal model. The relationship between calcium concentrations and pretreatment conditions (a series vs. simultaneous, i.e., first ethanol and then EDTA in water solution, the reverse, or EDTA in ethanol) was established and the optimal condition for prevention of BHV calcification was determined. The mechanistic studies on anticalcification effects exerted by particular pretreatment sequences were also conducted using FTIR and differential scanning calorimetry (DSC). The sequential pretreatment of CEM first with ethanol and then EDTA in water solution significantly decreased the calcification rate of CEM compared the control. The percentage of prevention of calcification by the serial treatment of ethanol (80% v/v) and then EDTA in water solutions decreased, as the concentration of elastin in the CEM increased. The percentage of preventing calcification was 42%, 28.6%, and 22.9% for CEM containing collagen and elastin ratios of 90:10, 50:50, 20:80, respectively. These results indicate that elastin is the major regulatory component of BHV calcification, and preventive effects on calcification increased only when CEM were pretreated with first ethanol and then EDTA in water solution. Moreover, the sequential effect is more apparent in the matrix of less elastin content, which is close to the physiological range. The sequential inhibitory effects of ethanol and

  10. Spatial and seasonal reef calcification in corals and calcareous crusts in the central Red Sea

    NASA Astrophysics Data System (ADS)

    Roik, Anna; Roder, Cornelia; Röthig, Till; Voolstra, Christian R.

    2016-06-01

    The existence of coral reef ecosystems critically relies on the reef carbonate framework produced by scleractinian corals and calcareous crusts (i.e., crustose coralline algae). While the Red Sea harbors one of the longest connected reef systems in the world, detailed calcification data are only available from the northernmost part. To fill this knowledge gap, we measured in situ calcification rates of primary and secondary reef builders in the central Red Sea. We collected data on the major habitat-forming coral genera Porites, Acropora, and Pocillopora and also on calcareous crusts (CC) in a spatio-seasonal framework. The scope of the study comprised sheltered and exposed sites of three reefs along a cross-shelf gradient and over four seasons of the year. Calcification of all coral genera was consistent across the shelf and highest in spring. In addition, Pocillopora showed increased calcification at exposed reef sites. In contrast, CC calcification increased from nearshore, sheltered to offshore, exposed reef sites, but also varied over seasons. Comparing our data to other reef locations, calcification in the Red Sea was in the range of data collected from reefs in the Caribbean and Indo-Pacific; however, Acropora calcification estimates were at the lower end of worldwide rates. Our study shows that the increasing coral cover from nearshore to offshore environments aligned with CC calcification but not coral calcification, highlighting the potentially important role of CC in structuring reef cover and habitats. While coral calcification maxima have been typically observed during summer in many reef locations worldwide, calcification maxima during spring in the central Red Sea indicate that summer temperatures exceed the optima of reef calcifiers in this region. This study provides a foundation for comparative efforts and sets a baseline to quantify impact of future environmental change in the central Red Sea.

  11. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-07-01

    Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better

  12. Effects of Hydrogen Peroxide on Coral Photosynthesis and Calcification

    NASA Astrophysics Data System (ADS)

    Higuchi, T.; Fujimura, H.; Arakaki, T.; Oomori, T.

    2007-12-01

    The widely-observed decline of coral reefs is considered to be caused by changes in the environment by natural and anthropogenic activities. As one important factor, the run-off of various matters from human activities to the coastal seawater poses stresses to the corals by degrading the quality of the seawater. In Okinawa, Japan, red- soil running off from the developed land has been a major environmental issue since 1980s. Hydrogen peroxide (HOOH), a strong active oxygen species, is one of the photochemically formed chemicals in the red-soil-polluted seawater. Recent photochemical studies of seawater showed that HOOH photo-formation was faster in the red- soil-polluted seawater than clean seawater. We studied the effects of HOOH on corals by studying the changes in coral carbon metabolisms such as photosynthesis and calcification, which are indicators of the physiological state of a coral colony. The corals were exposed to various concentrations of HOOH (0, 0.3, 3 μM). Two massive coral species of Porites sp. and Goniastrea aspera and one branch coral of Galaxea facicularis were used for the exposure experiments. The control experiments showed that when no HOOH was added, metabolisms of each coral colony were relatively stable. On the other hand, when HOOH was added to the seawater, we observed obvious changes in the coral metabolisms in all the coral species. When 0.3 μM HOOH was added, photosynthesis decreased by 14% and calcification decreased by 17% within 3 days, compared with the control. When 3 μM HOOH was added, photosynthesis decreased by 21% and calcification decreased by 41% within 3 days, compared with the control. Our study showed that higher concentrations of HOOH posed more stress to the coral colonies.

  13. Quantification of breast arterial calcification using full field digital mammography.

    PubMed

    Molloi, Sabee; Xu, Tong; Ducote, Justin; Iribarren, Carlos

    2008-04-01

    Breast arterial calcification is commonly detected on some mammograms. Previous studies indicate that breast arterial calcification is evidence of general atherosclerotic vascular disease and it may be a useful marker of coronary artery disease. It can potentially be a useful tool for assessment of coronary artery disease in women since mammography is widely used as a screening tool for early detection of breast cancer. However, there are currently no available techniques for quantification of calcium mass using mammography. The purpose of this study was to determine whether it is possible to quantify breast arterial calcium mass using standard digital mammography. An anthropomorphic breast phantom along with a vessel calcification phantom was imaged using a full field digital mammography system. Densitometry was used to quantify calcium mass. A calcium calibration measurement was performed at each phantom thickness and beam energy. The known (K) and measured (M) calcium mass on 5 and 9 cm thickness phantoms were related by M=0.964K -0.288 mg (r=0.997 and SEE=0.878 mg) and M=1.004K+0.324 mg (r=0.994 and SEE = 1.32 mg), respectively. The results indicate that accurate calcium mass measurements can be made without correction for scatter glare as long as careful calcium calibration is made for each breast thickness. The results also indicate that composition variations and differences of approximately 1 cm between calibration phantom and breast thickness introduce only minimal error in calcium measurement. The uncertainty in magnification is expected to cause up to 5% and 15% error in calcium mass for 5 and 9 cm breast thicknesses, respectively. In conclusion, a densitometry technique for quantification of breast arterial calcium mass was validated using standard full field digital mammography. The results demonstrated the feasibility and potential utility of the densitometry technique for accurate quantification of breast arterial calcium mass using standard digital

  14. Quantification of breast arterial calcification using full field digital mammography

    PubMed Central

    Molloi, Sabee; Xu, Tong; Ducote, Justin; Iribarren, Carlos

    2008-01-01

    Breast arterial calcification is commonly detected on some mammograms. Previous studies indicate that breast arterial calcification is evidence of general atherosclerotic vascular disease and it may be a useful marker of coronary artery disease. It can potentially be a useful tool for assessment of coronary artery disease in women since mammography is widely used as a screening tool for early detection of breast cancer. However, there are currently no available techniques for quantification of calcium mass using mammography. The purpose of this study was to determine whether it is possible to quantify breast arterial calcium mass using standard digital mammography. An anthropomorphic breast phantom along with a vessel calcification phantom was imaged using a full field digital mammography system. Densitometry was used to quantify calcium mass. A calcium calibration measurement was performed at each phantom thickness and beam energy. The known (K) and measured (M) calcium mass on 5 and 9 cm thickness phantoms were related by M=0.964K−0.288 mg (r=0.997 and SEE=0.878 mg) and M=1.004K+0.324 mg (r=0.994 and SEE=1.32 mg), respectively. The results indicate that accurate calcium mass measurements can be made without correction for scatter glare as long as careful calcium calibration is made for each breast thickness. The results also indicate that composition variations and differences of approximately 1 cm between calibration phantom and breast thickness introduce only minimal error in calcium measurement. The uncertainty in magnification is expected to cause up to 5% and 15% error in calcium mass for 5 and 9 cm breast thicknesses, respectively. In conclusion, a densitometry technique for quantification of breast arterial calcium mass was validated using standard full field digital mammography. The results demonstrated the feasibility and potential utility of the densitometry technique for accurate quantification of breast arterial calcium mass using standard digital

  15. Quantification of breast arterial calcification using full field digital mammography

    SciTech Connect

    Molloi, Sabee; Xu Tong; Ducote, Justin; Iribarren, Carlos

    2008-04-15

    Breast arterial calcification is commonly detected on some mammograms. Previous studies indicate that breast arterial calcification is evidence of general atherosclerotic vascular disease and it may be a useful marker of coronary artery disease. It can potentially be a useful tool for assessment of coronary artery disease in women since mammography is widely used as a screening tool for early detection of breast cancer. However, there are currently no available techniques for quantification of calcium mass using mammography. The purpose of this study was to determine whether it is possible to quantify breast arterial calcium mass using standard digital mammography. An anthropomorphic breast phantom along with a vessel calcification phantom was imaged using a full field digital mammography system. Densitometry was used to quantify calcium mass. A calcium calibration measurement was performed at each phantom thickness and beam energy. The known (K) and measured (M) calcium mass on 5 and 9 cm thickness phantoms were related by M=0.964K-0.288 mg (r=0.997 and SEE=0.878 mg) and M=1.004K+0.324 mg (r=0.994 and SEE=1.32 mg), respectively. The results indicate that accurate calcium mass measurements can be made without correction for scatter glare as long as careful calcium calibration is made for each breast thickness. The results also indicate that composition variations and differences of approximately 1 cm between calibration phantom and breast thickness introduce only minimal error in calcium measurement. The uncertainty in magnification is expected to cause up to 5% and 15% error in calcium mass for 5 and 9 cm breast thicknesses, respectively. In conclusion, a densitometry technique for quantification of breast arterial calcium mass was validated using standard full field digital mammography. The results demonstrated the feasibility and potential utility of the densitometry technique for accurate quantification of breast arterial calcium mass using standard digital

  16. Association of the vitamin D metabolism gene CYP24A1 with coronary artery calcification

    PubMed Central

    Shen, Haiqing; Bielak, Lawrence F.; Ferguson, Jane F.; Streeten, Elizabeth A.; Yerges-Armstrong, Laura M.; Liu, Jie; Post, Wendy; O'Connell, Jeffery R.; Hixson, James E.; Kardia, Sharon L.R.; Sun, Yan V.; Jhun, Mina A.; Wang, Xuexia; Mehta, Nehal N.; Li, Mingyao; Koller, Daniel L.; Hakonarson, Hakan; Keating, Brendan J.; Rader, Daniel J.; Shuldiner, Alan R.; Peyser, Patricia A.; Reilly, Muredach P.; Mitchell, Braxton D.

    2010-01-01

    Objective The Vitamin D endocrine system is essential for calcium homeostasis, and low levels of vitamin D metabolites have been associated with cardiovascular disease risk. We hypothesized that DNA sequence variation in genes regulating vitamin D metabolism and signaling pathways might influence variation in coronary artery calcification (CAC). Methods and Results We genotyped single nucleotide polymorphisms (SNPs) in GC, CYP27B1, CYP24A1, and VDR and tested their association with CAC quantity, as measured by electron beam computed tomography. Initial association studies were carried out in a discovery sample comprised of 697 Amish subjects and SNPs nominally associated with CAC quantity (4 SNPs in CYP24A1, P = 0.008-0.00003) were then tested for association with CAC quantity in two independent cohorts of subjects of European Caucasian ancestry (Genetic Epidemiology Network of Arteriopathy (GENOA) Study (n = 916) and The Penn Coronary Artery Calcification (PennCAC) sample (n = 2,061)). One of the four SNPs, rs2762939, was associated with CAC quantity in both GENOA (P = 0.007) and PennCAC (P = 0.01). In all three populations the rs2762939 C allele was associated with lower CAC quantity. Meta-analysis for the association of this SNP with CAC quantity across all three studies yielded a P value of 2.9 × 10-6. Conclusion A common SNP in the CYP24A1 gene was associated with CAC quantity in three independent populations. This result suggests a role for vitamin D metabolism in the development of CAC quantity. PMID:20847308

  17. Physico-chemical properties of hydrophilic and amphiphilic crosslinked systems that influence biological responses

    NASA Astrophysics Data System (ADS)

    Ejiasi, Angel

    The effect of physical, chemical, and biological cues on the behavior of smooth muscle cells (SMCs) and attachment of marine organisms was investigated. Both hydrophilic and amphiphilic crosslinked polymer networks with varying chemical and mechanical properties were used to direct biological responses. Poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels were fabricated with tunable mechanical properties by varying the di-functional monomer concentration in the feed composition. Amphiphilic hydrogels composed of 2-hydroxyethyl methacrylate (HEMA), 1,3-bis(3-methacryloxypropyl)tetrakis(trimethylsiloxy)disiloxane (MPTSDS), and tris(trimethylsiloxy)-3-methacryloxypropylsilane (TRIS) were copolymerized using ultraviolet (UV) light and a photo-initiator. Hydrogels prepared with varying concentration of di-functional monomer, MPTSDS, exhibited an order of magnitude difference in elastic moduli. Not only were the bulk material properties influenced by the crosslinking agent concentration in the feed composition, but the surface properties (i.e., contact angle and hysteresis) were influenced as well. Modulus (E) has been reported to be positively correlated with the settlement of marine organisms. However, this was not the case for the amphiphilic gels tested against biomolecules and marine organisms. Stiffer gels inhibited fouling of proteins and marine organism, Ulva linza, to a greater extent than the softer gels. Furthermore, the network structure, in regards to the molecular weight between crosslinks Mc, was found to have a greater influence on fouling. A strong correlation was observed between protein adsorption and Mc of the amphiphilic crosslinked networks compared to just the modulus and surface energy (Upsilon) alone. A higher correlation was also obtained between Mc and Ulva sporeling biomass than between sporeling biomass and elastic modulus E, exhibiting R² value of 0.98 and 0.38, respectively. The percent removal of sporeling biomass growth was shown to be

  18. Flexor Hallucis Longus Tendon Transfer for Calcific Insertional Achilles Tendinopathy.

    PubMed

    Howell, Michael A; Catanzariti, Alan R

    2016-01-01

    Calcific insertional Achilles tendinopathy can result in significant pain and disability. Although some patients respond to nonoperative therapy, many patients are at risk for long-term morbidity and unpredictable clinical outcomes. There is no evidence-based data to support the timing of operative invention, choice of procedures, or whether equinus requires treatment. This article suggests the need for a classification system based on physical examination and imaging to help guide treatment. There is an obvious need for evidence-based studies evaluating outcomes and for properly conducted scientific research to establish appropriate treatment protocols.

  19. Absence of gallium-67 avidity in diffuse pulmonary calcification

    SciTech Connect

    Lecklitner, M.L.; Foster, R.W.

    1985-09-01

    Diffuse pulmonary uptake by bone-seeking radiopharmaceuticals has been reported previously but, in the same patient, would pulmonary uptake of Ga-67 citrate yield clinically meaningful results. A patient with hypercalcemia and renal failure in whom bone scintigraphy demonstrated striking diffuse bilateral pulmonary uptake, but subsequent gallium imaging demonstrated no evidence of pulmonary uptake greater than body background, is discussed. We conclude that pulmonary uptake of gallium cannot be attributed to calcium deposition and should carry the same clinical significance in regard to inflammatory and malignant lesions as would be assigned to patients without pulmonary calcific deposits.

  20. NH4Cl Treatment Prevents Tissue Calcification in Klotho Deficiency

    PubMed Central

    Leibrock, Christina B.; Alesutan, Ioana; Voelkl, Jakob; Pakladok, Tatsiana; Michael, Diana; Schleicher, Erwin; Kamyabi-Moghaddam, Zahra; Quintanilla-Martinez, Leticia; Kuro-o, Makoto

    2015-01-01

    Klotho, a cofactor in suppressing 1,25(OH)2D3 formation, is a powerful regulator of mineral metabolism. Klotho-hypomorphic mice (kl/kl) exhibit excessive plasma 1,25(OH)2D3, Ca2+, and phosphate concentrations, severe tissue calcification, volume depletion with hyperaldosteronism, and early death. Calcification is paralleled by overexpression of osteoinductive transcription factor Runx2/Cbfa1, Alpl, and senescence-associated molecules Tgfb1, Pai-1, p21, and Glb1. Here, we show that NH4Cl treatment in drinking water (0.28 M) prevented soft tissue and vascular calcification and increased the life span of kl/kl mice >12-fold in males and >4-fold in females without significantly affecting extracellular pH or plasma concentrations of 1,25(OH)2D3, Ca2+, and phosphate. NH4Cl treatment significantly decreased plasma aldosterone and antidiuretic hormone concentrations and reversed the increase of Runx2/Cbfa1, Alpl, Tgfb1, Pai-1, p21, and Glb1 expression in aorta of kl/kl mice. Similarly, in primary human aortic smooth muscle cells (HAoSMCs), NH4Cl treatment reduced phosphate-induced mRNA expression of RUNX2/CBFA1, ALPL, and senescence-associated molecules. In both kl/kl mice and phosphate-treated HAoSMCs, levels of osmosensitive transcription factor NFAT5 and NFAT5-downstream mediator SOX9 were higher than in controls and decreased after NH4Cl treatment. Overexpression of NFAT5 in HAoSMCs mimicked the effect of phosphate and abrogated the effect of NH4Cl on SOX9, RUNX2/CBFA1, and ALPL mRNA expression. TGFB1 treatment of HAoSMCs upregulated NFAT5 expression and prevented the decrease of phosphate-induced NFAT5 expression after NH4Cl treatment. In conclusion, NH4Cl treatment prevents tissue calcification, reduces vascular senescence, and extends survival of klotho-hypomorphic mice. The effects of NH4Cl on vascular osteoinduction involve decrease of TGFB1 and inhibition of NFAT5-dependent osteochondrogenic signaling. PMID:25644113

  1. [Brain calcifications: a case presentation of congenital toxoplasmosis].

    PubMed

    Ávila, Mauricio J; Rodríguez-Restrepo, Andrea

    2014-12-18

    Toxoplasmosis is a common disease in Latin America. The infection has a major impact on public health worldwide. Congenital toxoplasmosis is part of the spectrum of the disease and the consequences for the newborn are devastating. In this article, we present a case of brain calcifications and hydrocephalus secondary to infection with Toxoplasma gondii in a newborn, as well as the outcome during follow-up and long-term sequelae. It is of high importance for the clinician to think about this disease, due to its high prevalence in Latin America, and to adopt adequate measures for its prevention and timely management in order to reduce long-term sequelae.

  2. Environmental controls on daytime net community calcification on a Red Sea reef flat

    NASA Astrophysics Data System (ADS)

    Bernstein, W. N.; Hughen, K. A.; Langdon, C.; McCorkle, D. C.; Lentz, S. J.

    2016-06-01

    Coral growth and carbonate accumulation form the foundation of the coral reef ecosystem. Changes in environmental conditions due to coastal development, climate change, and ocean acidification may pose a threat to net carbonate production in the near future. Controlled laboratory studies demonstrate that calcification by corals and coralline algae is sensitive to changes in aragonite saturation state (Ωa), as well as temperature, light, and nutrition. Studies also show that the dissolution rate of carbonate substrates is impacted by changes in carbonate chemistry. The sensitivity of coral reefs to these parameters must be confirmed and quantified in the natural environment in order to predict how coral reefs will respond to local and global changes, particularly ocean acidification. We estimated the daytime hourly net community metabolic rates, both net community calcification (NCC) and net community productivity (NCP), at Sheltered Reef, an offshore platform reef in the central Red Sea. Average NCC was 8 ± 3 mmol m-2 h-1 in December 2010 and 11 ± 1 mmol m-2 h-1 in May 2011, and NCP was 21 ± 7 mmol m-2 h-1 in December 2010 and 44 ± 4 mmol m-2 h-1 in May 2011. We also monitored a suite of physical and chemical properties to help relate the rates at Sheltered Reef to published rates from other sites. While previous research shows that short-term field studies investigating the NCC-Ωa relationship have differing results due to confounding factors, it is important to continue estimating NCC in different places, seasons, and years, in order to monitor changes in NCC versus Ω in space and time, and to ultimately resolve a broader understanding of this relationship.

  3. Influence of Fluorination on the Conformational Properties and Hydrogen-Bond Acidity of Benzyl Alcohol Derivatives

    PubMed Central

    Bogdan, Elena; Compain, Guillaume; Mtashobya, Lewis; Le Questel, Jean-Yves; Besseau, François; Galland, Nicolas; Linclau, Bruno; Graton, Jérôme

    2015-01-01

    The effect of fluorination on the conformational and hydrogen-bond (HB)-donating properties of a series of benzyl alcohols has been investigated experimentally by IR spectroscopy and theoretically with quantum chemical methods (ab initio (MP2) and DFT (MPWB1K)). It was found that o-fluorination generally resulted in an increase in the HB acidity of the hydroxyl group, whereas a decrease was observed upon o,o′-difluorination. Computational analysis showed that the conformational landscapes of the title compounds are strongly influenced by the presence of o-fluorine atoms. Intramolecular interaction descriptors based on AIM, NCI and NBO analyses reveal that, in addition to an intramolecular OH⋅⋅⋅F interaction, secondary CH⋅⋅⋅F and/or CH⋅⋅⋅O interactions also occur, contributing to the stabilisation of the various conformations, and influencing the overall HB properties of the alcohol group. The benzyl alcohol HB-donating capacity trends are properly described by an electrostatic potential based descriptor calculated at the MPWB1K/6-31+G(d,p) level of theory, provided solvation effects are taken into account for these flexible HB donors. PMID:26130594

  4. Influence of different ions doping on the antibacterial properties of MgO nanopowders

    NASA Astrophysics Data System (ADS)

    Rao, Yuanyuan; Wang, Wei; Tan, Fatang; Cai, Yuncheng; Lu, Junwen; Qiao, Xueliang

    2013-11-01

    Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li+, Zn2+ and Ti4+) were synthesized by a sol-gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.

  5. The influence of substrate temperature on the tribo- mechanical properties of chromium nitride thin films

    NASA Astrophysics Data System (ADS)

    Merie, V. V.; Negrea, G.; Modi, E.

    2016-08-01

    Different nitrides such as titanium nitride, chromium nitride and so on are used in a widespread range of applications such as cutting tools, medical implants, and microelectromechanical devices and all that due to their mechanical, physical and chemical properties. The aim of this study is to obtain chromium nitride thin films and to characterize them by atomic force microscopy investigations. The chromium nitride thin films were deposited by reactive magnetron sputtering on silicon substrates. During the deposition process, the discharge current, the argon and nitrogen flows, the pressure inside the chamber and the deposition time were kept constant. A chromium target with a purity of 99.95 % was used. Some of the films were deposited after a chromium buffer layer was previously deposited on the silicon substrate. The deposition was carried out when substrate temperature was at room temperature, at 300 and 500°C respectively. Once the films were deposited, atomic force microscopy investigations were performed in order to emphasize the influence of the substrate temperature on the topographical, mechanical and tribological characteristics. The results pointed out an important influence of the substrate temperature on topographical, mechanical and tribological properties of the investigated chromium nitride thin films.

  6. Influence of soil properties on copper toxicity for two soil invertebrates.

    PubMed

    Criel, Peggy; Lock, Koen; Eeckhout, Hilde Van; Oorts, Koen; Smolders, Erik; Janssen, Colin R

    2008-08-01

    Although a large body of evidence indicates that metal toxicity to soil organisms is affected by physicochemical soil properties, use of this knowledge in ecological risk assessments is limited because of the lack of a model applicable to a wide range of soils. To study the effect of soil characteristics on the toxicity of copper to terrestrial invertebrates, chronic toxicity tests with Eisenia fetida and Folsomia candida were performed in 19 European field soils. These soils were carefully selected to cover the range of toxicity-influencing parameters encountered in the European Union. Toxicity values varied greatly among soils, with 28-d median effect concentrations ranging from 72.0 to 781 mg Cu/kg dry weight for E. fetida and from 45.4 to 2,270 mg Cu/kg dry weight for F. candida. For both species, variation in copper toxicity values was best explained by differences in the actual cation-exchange capacity (CEC) at soil pH. Using the obtained regression algorithms, the observed toxicity could, in most cases, be predicted within a factor of two for E. fetida and within a factor of three for F. candida. The developed models were validated in three additional European field soils, a standard artificial soil and a standard field soil. The presented regression equations, based on the actual CEC, offer an easy-to-apply method for taking the influence of soil properties on metal toxicity into account.

  7. Influence of surface and interface properties on the electrical conductivity of silicon nanomembranes

    NASA Astrophysics Data System (ADS)

    Zhao, X.-F.; Scott, S.; Huang, M.; Peng, W.; Savage, D.; Eriksson, M.; Lagally, M.

    2010-03-01

    We investigate the electronic transport properties of silicon nanomembranes (SiNMs) on oxide by the van der Pauw method. SiNMs, thin sheets of single-crystal Si, feature an extreme sensitivity of electronic transport properties to surface and interface condition, because of the large surface-to-volume ratio. Removing the top oxide with HF reduces the sheet resistance four orders of magnitude for the thinnest NMs (˜20nm) [1], a value much greater than can be accounted for by simply reducing interface traps. We compare SiNMs prepared with HF to H terminations prepared via CVD, to identify which factors control this change in conductivity. We also perform a forming gas (5% H2 in N2) anneal on oxidized NMs. The sheet resistance drops relative to unannealed NMs, demonstrating the influence of states at Si/SiO2 interfaces. A qualitative model that includes these several factors influencing the sheet resistance is described. [4pt] [1] Scott S. et al, ACS Nano 3 (2009) 1683.

  8. Preparation of thiomer microparticles and in vitro evaluation of parameters influencing their mucoadhesive properties.

    PubMed

    Albrecht, K; Zirm, E J; Palmberger, T F; Schlocker, W; Bernkop-Schnürch, A

    2006-01-01

    It was the aim of this study to develop mucoadhesive microparticulate delivery systems based on thiomers and to investigate parameters influencing their mucoadhesive properties. Microparticles were prepared via coazervation of thiolated or unmodified polycarbophil with fluorescein-diacetate as marker. The protective effect of the polymers toward enzymatic hydrolysis by intestinal enzymes was investigated. Mucoadhesion studies with microparticles, applied in dry and prehydrated form, were performed by ascertaining their residence time on intestinal mucosa. Furthermore, the influence of the amount of thiol groups on mucoadhesion was studied in vitro. Results showed that in comparison to unmodified polycarbophil, thiolated polycarbophil provided a more than 3-fold higher protective effect for the incorporated marker fluorescein-diacetate toward hydrolysis. When being applied in dry form 23.4 +/- 4.8% of the fluorescence marker being embedded in thiomer microparticles remained adhering to the intestinal mucosa within 3 h. In contrast, only 11.6 +/- 2.0% of the marker remained on the mucosa, when the thiomer microparticles were applied in prehydrated form. In addition, tests performed to assess the impact of the amount of thiol groups pointed out that a high amount of thiol groups is advantageous in order to further improve mucoadhesive properties. This knowledge should contribute to the design of highly efficient drug delivery systems being based on thiomer microparticles.

  9. How contamination sources and soil properties can influence the Cd and Pb bioavailability to snails.

    PubMed

    Pauget, Benjamin; Gimbert, Frédéric; Coeurdassier, Mickael; Druart, Coline; Crini, Nadia; de Vaufleury, Annette

    2016-02-01

    To better understand the fate of metals in the environment, numerous parameters must be studied, such as the soil properties and the different sources of contamination for the organisms. Among bioindicators of soil quality, the garden snail (Cantareus aspersus) integrates multiple sources (e.g. soil, plant) and routes (e.g. digestive, cutaneous) of contamination. However, the contribution of each source on metal bioavailability and how soil properties influence these contributions have never been studied when considering the dynamic process of bioavailability. Using accumulation kinetics, this study showed that the main assimilation source of Cd was lettuce (68%), whereas the main source of Pb was the soil (90%). The plant contribution increased in response to a 2-unit soil pH decrease. Unexpectedly, an increase in the soil contribution to metal assimilation accompanied an increase in the organic matter (OM) content of the soil. For both metals, no significant excretion and influence of source on excretion have been modelled either during exposure or depuration. This study highlights how the contribution of different sources to metal bioavailability changes based on changes in soil parameters, such as pH and OM, and the complexity of the processes that modulate metal bioavailability.

  10. Influence of air mass origin on aerosol properties at a remote Michigan forest site

    NASA Astrophysics Data System (ADS)

    VanReken, T. M.; Mwaniki, G. R.; Wallace, H. W.; Pressley, S. N.; Erickson, M. H.; Jobson, B. T.; Lamb, B. K.

    2015-04-01

    The northern Great Lakes region of North America is a large, relatively pristine area. To date, there has only been limited study of the atmospheric aerosol in this region. During summer 2009, a detailed characterization of the atmospheric aerosol was conducted at the University of Michigan Biological Station (UMBS) as part of the Community Atmosphere-Biosphere Interactions Experiment (CABINEX). Measurements included particle size distribution, water-soluble composition, and CCN activity. Aerosol properties were strongly dependent on the origin of the air masses reaching the site. For ∼60% of the study period, air was transported from sparsely populated regions to the northwest. During these times aerosol loadings were low, with mean number and volume concentrations of 1630 cm-3 and 1.91 μm3 cm-3, respectively. The aerosol during clean periods was dominated by organics, and exhibited low hygroscopicities (mean κ = 0.18 at s = 0.3%). When air was from more populated regions to the east and south (∼29% of the time), aerosol properties reflected a stronger anthropogenic influence, with 85% greater particle number concentrations, 2.5 times greater aerosol volume, six times more sulfate mass, and increased hygroscopicity (mean k = 0.24 at s = 0.3%). These trends are have the potential to influence forest-atmosphere interactions and should be targeted for future study.

  11. Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites.

    PubMed

    Bertolo, Marcus Vinicius Loureiro; Moraes, Rita de Cássia Martins; Pfeifer, Carmem; Salgado, Vinícius Esteves; Correr, Ana Rosa Costa; Schneider, Luis Felipe J

    2017-01-01

    The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis{2-(methacryloyloxy) ethyl} phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RPmax) were determined by near infrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey's test (a=0.05). BAPO presented the highest DC and RPmax values for both series. SAFCs presented lower DC and RPmax for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.

  12. Influences of sediment properties and macrophytes on phosphorous speciation in the intertidal marsh.

    PubMed

    Shao, Xuexin; Liang, Xinqiang; Wu, Ming; Gu, Binhe; Li, Wenhua; Sheng, Xuancai; Wang, Shaoxian

    2014-09-01

    Phosphorus (P) in wetlands is mainly bound to sediment in various species, which is essential to predict water column P levels. The purpose of this work is to understand the influences of sediment properties and vegetation types on P speciation. Sediments under four vegetation types in the tidal flat and offshore sandbar in Hangzhou Bay of China were collected seasonally. The rank order of P species in sediment based on concentration was exchangeable P (Exch-P) < iron/aluminum-bound P (Fe/Al-P) < organic P (Org-P) < calcium-bound P (Ca-P). Sediment total phosphorus (TP) and Fe/Al-P concentrations were lower in offshore sandbar than those of tidal flat, reflecting effects of anthropogenic contamination in the latter. Sediment particle size distribution strongly affected P speciation, as indicated by a significant correlation between them. Total phosphorus and Org-P concentrations in vegetated sediments were higher than those of bare mudflat. Additionally, there was a significant negative correlation between Ca-P and Org-P, and Fe/Al-P, indicating the presence of vegetation which may result in P speciation by converting Ca-P to soluble and active P and higher Org-P. Overall, sediment particle size distribution is the most fundamental physical property that affects P speciation, and vegetation types are important factors that influence Org-P concentration.

  13. Influence of temperature-dependent material properties on heat transfer in the turbulent flow over a flat plate

    NASA Astrophysics Data System (ADS)

    Wehle, F.; Brandt, F.

    The influence of temperature dependence of material properties on heat transfer in a turbulent plate boundary layer is investigated using differential equations for the velocity and temperature fields of even, steady, and compressible boundary layer flows. The results are compared with the well-known material property correction factors of Zhukauskas (1966), Sieder and Tate (1936), and Hufschmidt and Bruck (1968).

  14. Influence of semi-volatile aerosol on physical and optical properties of aerosol in Kathmandu valley

    NASA Astrophysics Data System (ADS)

    Shrestha, Sujan; Praveen, Ps; Adhikary, Bhupesh; Shrestha, Kundan; Panday, Arnico

    2016-04-01

    A field study was conducted in the urban atmosphere of Kathmandu valley to study the influence of the semi-volatile aerosol fraction on physical and optical properties of aerosols. The study was carried out during the 2015 pre-monsoon period. Experimental setup consisted of air from an ambient air inlet being split to two sets of identical sampling instruments. The first instrument received the ambient sample directly, while the second instrument received the air sample through a thermodenuder (TDD). Four sets of experiments were conducted to understand aerosol number, size distribution, scattering and absorption properties using Condensation Particle Counter (CPC), Scanning Mobility Particle Sizer (SMPS), Aethalometer (AE33) and Nephelometer. The influence of semi-volatile aerosols was calculated from the fraction of particles evaporated in the TDD at set temparetures: room temperature, 50°C, 100°C, 150°C, 200°C, 250°C and 300°C. Results show that, with increasing temperature, the evaporated fraction of semi-volatile aerosol also increased. At room temperature the fraction of semi-volatile aerosols was 12% while at 300°C it was as high as to 49%. Aerosol size distribution analysis shows that with an increase in TDD temperature from 50°C to 300°C, peak mobility diameter of particles shifted from around 60nm to 40nm. However we found little change in effective diameter of aerosol size distribution with increase in set TDD temperature. The change in size of aerosols due to loss of semi-volatile component has a stronger influence (~70%) in higher size bins when compared to at lower size bins (~20%). Studies using the AE33 showed that absorption by black carbon (BC) is amplified due to influence of semi-volatile aerosols by upto 37% at 880nm wavelength. Similarly nephelometer measurements showed that upto 71% of total scattering was found to be contributed by semi-volatile aerosol fraction. The scattering Angstrom Exponent (SAE) of semi-volatile aerosol

  15. Caseous Calcification of Mitral Annulus: A Rare Monster Leading to Cerebrovascular Accident.

    PubMed

    Memon, Sarfaraz; Chhabra, Lovely; Krainski, Felix; Parker, Matthew W; Swales, Heather

    2015-10-01

    Caseous calcification of the mitral annulus (CCMA) is a rare variant of mitral annular calcification that maybe easily misdiagnosed or confused with an abscess, a tumor, or infective vegetation. The main pathophysiological mechanism leading to CCMA involves degeneration and calcium deposition on the mitral valve. We present a case of CCMA to help understand this clinical entity.

  16. Dietary vitamin K and therapeutic warfarin alter susceptibility to vascular calcification in experimental chronic kidney disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leading cause of death in patients with chronic kidney disease (CKD) is cardiovascular disease (CVD), with vascular calcification (VC) being a key modifier of disease progression. A local regulator of vascular calcification is vitamin K. This gamma-glutamyl carboxylase substrate is an essential ...

  17. Resveratrol Ameliorated Vascular Calcification by Regulating Sirt-1 and Nrf2.

    PubMed

    Zhang, P; Li, Y; Du, Y; Li, G; Wang, L; Zhou, F

    2016-12-01

    Pathologic vascular calcification is a significant reason for mortality and morbidity in patients who suffer from end-stage renal disease (ESRD). Resveratrol, a scavenger for many free radicals, is a crucial compound for biomedicine. However, the role and mechanism of resveratrol in vascular calcification is still unknown. In this study, to mimic vascular calcification in ESRD, we used β-glyceophosphate to stimulate the rat vascular smooth muscle cells (RASMCs). We investigate the therapeutic role of resveratrol pretreatment in vascular calcification. In the current in vitro study, we observe the effects of resveratrol on improving intracellular calcium deposition and protecting against mitochondria dysfunction in calcific RASMCs. Resveratrol decreased the mRNA level of fibroblast growth factor-23, then increased the mRNA level of klotho and the nuclear transcription factor NF-E2-related factor 2 (nuclear factor-erythroid 2-related factor 2 [Nrf2]) in RASMCs after calcification. Further, resveratrol activated the expression of sirtuin-1 and Nrf2, and inhibited the expression of osteopontin, runt-related transcription factor 2, and heme oxygenase-1. Our study shows that resveratrol could ameliorate oxidative injury of RASMCs by preventing vascular calcification-induced calcium deposition and mitochondria dysfunction through involving sirtuin-1 and Nrf2. These results might indicate a novel role for resveratrol in resistance to oxidative stress for ESRD patients suffering from vascular calcification.

  18. Characterization of deposits in patients with calcific tendinopathy of the supraspinatus. Role of phytate and osteopontin.

    PubMed

    Grases, Felix; Muntaner-Gimbernat, Lorenzo; Vilchez-Mira, Mar; Costa-Bauzá, Antonia; Tur, Fernando; Prieto, Rafel Maria; Torrens-Mas, Margalida; Vega, Fabiana Gisela

    2015-04-01

    Calcific tendinopathy of the tendons of the rotator cuff is common in adults. These calcifications tend to be reabsorbed after a period of acute pain. This study evaluated the morphologic characteristics of calcific deposits and the participation of phytate and osteopontin (OPN) in their development. Calcific deposits were removed from 21 patients with calcific tendinopathy by ultrasound-guided needle puncture under local anesthesia. The removed deposits were evaluated by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The amounts of calcium and phosphorus in the deposits were semi-quantitatively determined by energy dispersive X-ray analysis. Phytate was determined in 2 h urine samples, and OPN was extracted from a pool of deposits. The calcific deposits consisted of amorphous and poorly crystalline carbonated hydroxyapatite containing molecular water and organic matter. OPN was associated with the hydroxyapatite deposits. Phytate concentrations were significantly lower in the urine of patients with calcific tendinopathy than in healthy controls. The deficit in crystallization inhibitors such as phytate, and the presence of regulators such as OPN, may play important roles in the development of calcific tendinopathy.

  19. Osteopontin protects against high phosphate-induced nephrocalcinosis and vascular calcification.

    PubMed

    Paloian, Neil J; Leaf, Elizabeth M; Giachelli, Cecilia M

    2016-05-01

    Pathologic calcification is a significant cause of increased morbidity and mortality in patients with chronic kidney disease. The precise mechanisms of ectopic calcification are not fully elucidated, but it is known to be caused by an imbalance of procalcific and anticalcific factors. In the chronic kidney disease population, an elevated phosphate burden is both highly prevalent and a known risk factor for ectopic calcification. Here we tested whether osteopontin, an inhibitor of calcification, protects against high phosphate load-induced nephrocalcinosis and vascular calcification. Osteopontin knockout mice were placed on a high phosphate diet for 11 weeks. Osteopontin deficiency together with phosphate overload caused uremia, nephrocalcinosis characterized by substantial renal tubular and interstitial calcium deposition, and marked vascular calcification when compared with control mice. Although the osteopontin-deficient mice did not exhibit hypercalcemia or hyperphosphatemia, they did show abnormalities in the mineral metabolism hormone fibroblast growth factor-23. Thus, endogenous osteopontin plays a critical role in the prevention of phosphate-induced nephrocalcinosis and vascular calcification in response to high phosphate load. A better understanding of osteopontin's role in phosphate-induced calcification will hopefully lead to better biomarkers and therapies for this disease, especially in patients with chronic kidney disease and other at-risk populations.

  20. Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates

    NASA Astrophysics Data System (ADS)

    Unruh, Oliver

    2016-09-01

    In order to reduce noise emitted by vibrating structures additional damping treatments such as constraint layer damping or embedded elastomer layers can be used. To save weight and cost, the additional damping is often placed at some critical locations of the structure, what leads to spatially inhomogeneous distribution of damping. This inhomogeneous distribution of structural damping leads to an occurrence of complex vibration modes, which are no longer dominated by pure standing waves, but by a superposition of travelling and standing waves. The existence of complex vibration modes raises the question about their influence on sound radiation. Previous studies on the sound radiation of complex modes of rectangular plates reveal, that, depending on the direction of travelling waves, the radiation efficiency of structural modes can slightly decrease or significantly increase. These observations have been made using a rectangular plate with a simple inhomogeneous damping configuration which includes a single plate boundary with a higher structural damping ratio. In order to answer the question about the influence of other possible damping configurations on the sound radiation properties, this paper addresses the self- and mutual-radiation efficiencies of the resulting complex vibration modes. Numerical simulations are used for the calculation of complex structural modes of different inhomogeneous damping configurations with varying geometrical form and symmetry. The evaluation of self- and mutual-radiation efficiencies reveals that primarily the symmetry properties of the inhomogeneous damping distribution affect the sound radiation characteristics. Especially the asymmetric distributions of inhomogeneous damping show a high influence on the investigated acoustic metrics. The presented study also reveals that the acoustic cross-coupling between structural modes, which is described by the mutual-radiation efficiencies, generally increases with the presence of

  1. The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

    NASA Astrophysics Data System (ADS)

    Mackay, Rebecca A.; Maier, Ralph D.

    1982-10-01

    The influence of orientation on the stress rapture properties of MAR-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 °C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives at 774 °C were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently, a short stress rupture life. Those crystals having orientations within about 25° of the [001] exhibited significantly longer lives when their orientations were closer to the [001]-[011] boundary of the stereographic triangle than to the [001]-[1l 1] boundary, because they required smaller rotations to produce intersecting slip and the onset of second-stage creep. Thus, the direction off the [001], as well as the number of degrees off the [001], has a major influence on the stress rapture lives of single crystals in this temperature regime.

  2. Influence of heat treatment on the metal properties of the high-temperature rotors of large steam turbines

    SciTech Connect

    Farafonov, V.K.; Platkova, L.M.; Sakulin, A.A.

    1983-01-01

    The authors describe the development of heat treatment cycles for the hardening of large rotors made from 88- and 106-tonne ingots (25Kh1M1FA steel) with a view to improving the properties in the axial zone of the rotors. The mechanical properties, the tendency to brittle fracture and the metal structure are examined as a function of the heat treatment conditions. The influence of carbon segregation on the properties of the axial zone of the rotors is investigated.

  3. The Influence of Component Alignment and Ligament Properties on Tibiofemoral Contact Forces in Total Knee Replacement

    PubMed Central

    Smith, Colin R.; Vignos, Michael F.; Lenhart, Rachel L.; Kaiser, Jarred; Thelen, Darryl G.

    2016-01-01

    The study objective was to investigate the influence of coronal plane alignment and ligament properties on total knee replacement (TKR) contact loads during walking. We created a subject-specific knee model of an 83-year-old male who had an instrumented TKR. The knee model was incorporated into a lower extremity musculoskeletal model and included deformable contact, ligamentous structures, and six degrees-of-freedom (DOF) tibiofemoral and patellofemoral joints. A novel numerical optimization technique was used to simultaneously predict muscle forces, secondary knee kinematics, ligament forces, and joint contact pressures from standard gait analysis data collected on the subject. The nominal knee model predictions of medial, lateral, and total contact forces during gait agreed well with TKR measures, with root-mean-square (rms) errors of 0.23, 0.22, and 0.33 body weight (BW), respectively. Coronal plane component alignment did not affect total knee contact loads, but did alter the medial–lateral load distribution, with 4 deg varus and 4 deg valgus rotations in component alignment inducing +17% and −23% changes in the first peak medial tibiofemoral contact forces, respectively. A Monte Carlo analysis showed that uncertainties in ligament stiffness and reference strains induce ±0.2 BW uncertainty in tibiofemoral force estimates over the gait cycle. Ligament properties had substantial influence on the TKR load distributions, with the medial collateral ligament and iliotibial band (ITB) properties having the largest effects on medial and lateral compartment loading, respectively. The computational framework provides a viable approach for virtually designing TKR components, considering parametric uncertainty and predicting the effects of joint alignment and soft tissue balancing procedures on TKR function during movement. PMID:26769446

  4. Influence of metallic vapours on thermodynamic and transport properties of two-temperature air plasma

    NASA Astrophysics Data System (ADS)

    Zhong, Linlin; Wang, Xiaohua; Cressault, Yann; Teulet, Philippe; Rong, Mingzhe

    2016-09-01

    The metallic vapours (i.e., copper, iron, and silver in this paper) resulting from walls and/or electrode surfaces can significantly affect the characteristics of air plasma. Different from the previous works assuming local thermodynamic equilibrium, this paper investigates the influence of metallic vapours on two-temperature (2 T) air plasma. The 2 T compositions of air contaminated by Cu, Fe, and Ag are first determined based on Saha's and Guldberg-Waage's laws. The thermodynamic properties (including mass density, specific enthalpy, and specific heat) are then calculated according to their definitions. After determining the collision integrals for each pair of species in air-metal mixtures using the newly published methods and source data, the transport coefficients (including electrical conductivity, viscosity, and thermal conductivity) are calculated for air-Cu, air-Fe, and air-Ag plasmas with different non-equilibrium degree θ (Te/Th). The influences of metallic contamination as well as non-equilibrium degree are discussed. It is found that copper, iron, and silver exist mainly in the form of Cu2, FeO, and AgO at low temperatures. Generally, the metallic vapours increase mass density at most temperatures, reduce the specific enthalpy and specific heat in the whole temperature range, and affect the transport properties remarkably from 5000 K to 20 000 K. The effect arising from the type of metals is little except for silver at certain temperatures. Besides, the departure from thermal equilibrium results in the delay of dissociation and ionization reactions, leading to the shift of thermodynamic and transport properties towards a higher temperature.

  5. Calculating acoustical properties of cells: influence of surface topography and liquid layer between cell and substrate.

    PubMed

    Kundu, T; Bereiter-Hahn, J; Hillmann, K

    1992-05-01

    In this paper, a mathematical formulation is presented to compute the V(z) of a tapering layered solid and applying this formulation to the determination of acoustic properties of biological cells and tissues. The formulation is adopted in the simplex inversion algorithm to obtain the acoustic properties of a tapering cell from its V(z) values. The influence of two parameters had been considered: The tapering angle and the presence of a thin liquid layer present between cells and the substratum to which they adhere. Up to a tapering angle less than 10 degrees, it can be safely neglected. However, if a larger angle is neglected, then the acoustic wave velocity in the cell is overestimated. Cell thickness estimation is not affected significantly when the tapering angle is ignored. The calculations of acoustic properties of cells are considerably influenced by the introduction of a thin fluid layer between the solid substratum and the overlying cell, neglecting the presence of at least a very thin layer (20-30 nm), in general, results in a considerable overestimation of sound velocity. The reliability of the data calculated from V(z) values was ascertained using an independent method to determine cell thickness by calculating it from the interference fringe pattern obtained with the reflection-interference light microscope. The shape of the glutaraldehyde-fixed cells was similar to fried eggs. The highest sound velocities were found close to the periphery of the dome-shaped cell center. In the very center and over most of the area of the thin periphery, sound velocity was close to that in saline.

  6. Abdominal aortic calcification is not superior over other vascular calcification in predicting mortality in hemodialysis patients: a retrospective observational study

    PubMed Central

    2013-01-01

    Background KDIGO (Kidney Disease: Improving Global Outcomes) guidelines recommend that a lateral abdominal radiograph should be performed to assess vascular calcification (VC) in dialysis patients. However, abdominal aortic calcification is a prevalent finding, and it remains unclear whether other anatomical areas of VC can predict mortality more accurately. Methods A total of 217 maintenance hemodialysis patients were enrolled at the Sichuan Provincial People’s Hospital between July 2010 and March 2011. Radiographs of the abdomen, pelvis and hands were evaluated by a radiologist to evaluate the presence of VC. The correlation between different areas of VC and all-cause or cardiovascular mortality was analyzed using univariate and multivariate models. Results The prevalence of VC was 70.0% (152 patients), and most had abdominal aortic calcification (90.1%). During 26 ± 7 months of follow-up, 37 patients died. The VC score was independently associated with patient mortality. VC observed on abdominal radiographs (abdominal aortic calcification) was associated with all-cause mortality in models adjusted for cardiovascular risk factors (HR, 4.69; 95%CI, 1.60-13.69) and dialysis factors (HR, 3.38; 95%CI, 1.18-9.69). VC in the pelvis or hands was associated with all-cause mortality in the model adjusted for dialysis factors. When three combinations of VC in different radiographs were included in models, the presence of abdominal VC was only significantly associated with all-cause mortality in the integrated model. VC in the abdomen and pelvis was associated with all-cause mortality in the model adjusted for cardiovascular factors and the integrated model, but neither was significantly associated with cardiovascular mortality. VC in all radiographs was significantly associated with a more than 6-fold risk of all-cause mortality and a more than 5-fold risk of cardiovascular mortality compared to patients without VC. Conclusions VC in different arteries as shown on

  7. [Serpiginous calcifications in breast filariasis: A descriptor not included in the BI-RADS classification system].

    PubMed

    Mora-Encinas, J P; Martín-Martín, B; Martín-Martín, L; Mora-Monago, R

    2015-01-01

    Filariasis is a parasitic disease with a benign course caused by nematodes. Filariasis is endemic in some tropical regions, and immigration has made it increasingly common in some centers in Spain. The death of the parasites can lead to calcifications that are visible in mammograms; these calcifications have specific characteristics and should not be confused with those arising in other diseases. However, the appearance of calcifications due to filariasis is not included in the most common systems used for the classification of calcifications on mammograms (BI-RADS), and this can lead to confusion. In this article, we discuss the need to update classification systems and warn radiologists about the appearance of these calcifications to ensure their correct diagnosis and avoid confusion with other diseases.

  8. Vascular calcification in rheumatoid arthritis: prevalence, pathophysiological aspects and potential targets.

    PubMed

    Paccou, J; Brazier, M; Mentaverri, R; Kamel, S; Fardellone, P; Massy, Z A

    2012-10-01

    Individuals with rheumatoid arthritis (RA) are at increased risk for morbidity and mortality from cardiovascular disease. Excess cardiovascular mortality in RA patients cannot be fully explained by conventional cardiovascular risk factors. The purpose of this review is to discuss recent progress concerning the prevalence and pathophysiological aspects of vascular calcification in RA. RA patients have early-onset diffuse calcification involving multiple vascular beds compared to age and sex-matched controls. Pathogenesis of vascular calcification in RA patients is not fully understood, but specific mediators such as proinflammatory cytokines and not global inflammation could be involved. The possible link between osteoporosis and vascular calcification in RA will not be discussed. Finally, potential targets to reduce vascular calcification in RA will be discussed.

  9. Significant long-term increase of fossil fuel CO2 uptake from reduced marine calcification

    NASA Astrophysics Data System (ADS)

    Ridgwell, A.; Zondervan, I.; Hargreaves, J. C.; Bijma, J.; Lenton, T. M.

    2006-11-01

    Analysis of available plankton manipulation experiments demonstrates a previously unrecognized wide range of sensitivities of biogenic calcification to simulated anthropogenic acidification of the ocean, with the "lab rat" of planktic calcifiers, Emiliania huxleyi not representative of calcification generally. We assess the implications of the experimental uncertainty in plankton calcification response by creating an ensemble of realizations of an Earth system model that encapsulates a comparable range of uncertainty in calcification response. We predict a substantial future reduction in marine carbonate production, with ocean CO2 sequestration across the model ensemble enhanced by between 62 and 199 PgC by the year 3000, equivalent to a reduction in the atmospheric fossil fuel CO2 burden at that time of up to 13%. Concurrent changes in ocean circulation and surface temperatures contribute about one third to the overall importance of reduced plankton calcification.

  10. Calcific tendonitis of the tibialis posterior tendon at the navicular attachment

    PubMed Central

    Harries, Luke; Kempson, Susan; Watura, Roland

    2011-01-01

    Calcific tendinosis (tendonosis/tendonitis) is a condition which results from the deposition of calcium hydroxyapatite crystals in any tendon of the body. Calcific